CN1703731B - Flat panel display driving device and driving method - Google Patents

Abstract

A display panel driving device and a driving method which provide a high quality image and have no irregular brightness even after a long time use. When each light emitting element including a pixel is caused to emit light independently in turn, the value of the light emission drive current flowing is measured, and then the luminance is corrected for each input pixel data based on the above-mentioned light emission drive current value associated with the pixel corresponding to the input pixel data. According to another aspect, the voltage value of the drive voltage is adjusted in such a manner that one of each of the measured light emission drive current values is equal to a given reference current value. According to still another aspect, when an offset current component corresponding to a leakage current of the display panel is added to a current output from the driving voltage generating circuit, a current value is measured, and a resultant current is supplied to each pixel portion.

Description

Flat panel display driving device and driving method

technical field

The present invention relates to an active matrix display panel driving device and a driving method thereof. the

Background technique

In recent years, electroluminescent display devices (hereinafter referred to as EL display devices) combined with display panels using organic electroluminescent elements including pixels (hereinafter referred to as EL display elements) as light emitting elements have attracted great attention. Driving methods of flat panel displays using these EL display devices known in the art include simple matrix driving and active matrix driving. The advantage of an active matrix driven EL display device is that it consumes less power than a simple matrix type, and has less crosstalk between pixels, and is especially suitable for large-screen and high-resolution displays. the

Figure 1 shows the basic structure of an active matrix driven EL display device. the

As shown in FIG. 1, the EL display device includes a display panel 10 and a driving device 100 for driving the display panel 10 according to an image signal. the

Display panel 10 is composed of anode power supply line 16, cathode power supply line 17, scan lines _A1 to A _n (scanning electrodes) forming n horizontal scan lines on a screen, and each scan line crossing with _A1 to A _n m data lines (data electrodes) _B1 to _Bm are arranged. Also, the drive voltage Vc is applied to the anode power supply line 16, and the ground potential GND is applied to the cathode power supply line 17. In addition, EL units _E1,1 to _En,m having pixels are formed at each intersection of the scanning lines _A1 to _An and the data lines _B1 to _Bm in the above-described display panel 10.

FIG. 2 shows the internal structure of an embodiment of an EL unit E formed at the intersection of one scanning line A and one data line B. Referring to FIG. the

In FIG. 2, a gate G of a selected FET (Field Effect Transistor) 11 is connected to a scan line A, and a drain D is connected to a data line B. In FIG. The gate G of the transistor FET12 for light emission driving is connected to the source S of the FET11. A driving voltage Vc is applied to the FET 12 through an anode power supply line 16, and a capacitor 13 is connected between the gate G and the source S. In addition, the anode terminal of the EL element 15 is connected to the drain D of the FET 12 . A ground potential GND is applied to the cathode terminal of the EL element 15 through a cathode power supply line 17 . the

The driving device 100 selectively applies scan pulses to each of the scan lines _A1 to _An of the display panel 10 in sequence. Moreover, the driving device 100 generates pixel data pulses DP ₁ to DP _m synchronously with the timing of the above-mentioned scanning pulses applied according to the input image signal corresponding to each horizontal scanning line, and applies them to the data lines B ₁ to B _m respectively. . Each pixel data pulse DP has a pulse voltage according to a brightness level represented by an input image signal. Each EL cell connected to the scan line A to which the scan pulse is applied becomes a target of pixel data writing. The FET 11 in the EL unit E which is the target of pixel data writing is in a conduction state in response to the above-mentioned scan pulse, and the above-mentioned pixel data pulse DP supplied through the data line B is applied to the gate G of the FET 12 and the capacitor 13, respectively. . The FET 12 generates a light emission driving current according to the pulse voltage of the pixel data pulse DP, and supplies it to the EL element 15 . The EL element 15 emits light whose luminance is determined by the pulse voltage of the above-mentioned pixel data pulse DP according to the light emission driving current. At the same time, the capacitor 13 is charged according to the above pulse voltage of the pixel data pulse DP. With this charging method, the pulse voltage according to the brightness level indicated by the input image signal is maintained, thereby realizing so-called pixel data writing. When the target for writing pixel data is released, the FET11 is turned off, and the supply of the pixel data pulse DP to the gate G of the FET12 is stopped. However, during this time, since the voltage held by the capacitor 13 as described above continues to be applied to the gate G of the FET 12, the FET 12 keeps sending the above-mentioned light emission driving current to the EL element 15 continuously.

One of the characteristics of the EL element 15 is that the resistance value of the element itself gradually increases after prolonging the light emitting time. Since the frequency of light emission in response to an input image signal of each EL element ₁₅ is different among the EL units E1,1 to _En,m supported by the display panel 10, a difference occurs in the cumulative light emission time. Therefore, when the driving time of the display panel 10 is prolonged, the resistance of the EL elements becomes non-uniform, causing variations in luminance of light emission, resulting in problems such as irregular luminance on the screen and screen burning.

Invention introduction

An object of the present invention is to solve the above-mentioned problems by providing a display panel driving device and a driving method thereof which can be used for an extended time and can uniformly display high-quality images. the

Also, since the frequency of light emission according to the input image signal is different for each of the EL elements 15 in the above-mentioned EL units _E1,1 to _En,m , a difference occurs in the cumulative light emission time. Therefore, when the driving time of the display panel 10 is prolonged, the resistance of the EL elements becomes non-uniform, causing variations in luminance of light emission, resulting in problems such as irregular luminance on the screen and screen burning.

The present invention also solves the above-mentioned problems by providing a display panel driving device capable of permanently maintaining a brightness level of a screen within a given range, thereby preventing brightness irregularities in the screen, and a driving method thereof. the

The display panel driving device according to the first aspect of the present invention is a display panel driving device for driving a display panel formed by a plurality of light-emitting elements supporting pixels arranged in a matrix, and the display panel driving device includes:

A driving voltage generation circuit, which provides a driving voltage for each of the plurality of light-emitting elements through a power line;

a current measuring part for obtaining a current value flowing in the above-mentioned power supply line while causing each light emitting element to emit light sequentially and independently at the timing of the light emitting time of each light emitting element, thereby obtaining a current value corresponding to each pixel, and store it in memory as the measured current value assigned to each pixel;

a luminance correcting section for obtaining luminance-corrected pixel data by correcting a luminance level indicated by the pixel data corresponding to each pixel of the input image signal based on the above-mentioned measured current value of one pixel according to the pixel data stored in the memory ;as well as

The light-emitting driving part is used to make the above-mentioned light-emitting element emit light only during the image display light-emitting period in each frame period corresponding to the above-mentioned input image signal, and the period corresponding to the brightness-corrected pixel data. the

Moreover, the display panel driving method according to the first aspect of the present invention is a display panel driving method for driving a display panel formed by a plurality of light-emitting elements including pixels arranged in a matrix, and the display panel driving method includes the following steps:

The current measurement step is used to obtain the current value flowing in the above-mentioned power line while making each light-emitting element emit light independently at the timing of the light-emitting time of each light-emitting element, thereby obtaining the current value corresponding to each pixel;

a luminance correcting step for obtaining luminance by correcting a luminance level represented by pixel data corresponding to each pixel of the input image signal by means of the above-mentioned measured current value of one pixel based on the above-mentioned pixel data stored in the above-mentioned memory corrected pixel data; and

The light-emitting driving step is used to make the above-mentioned light-emitting element emit light only in the period of the above-mentioned brightness correction pixel data in the image display light-emitting period corresponding to each frame period of the above-mentioned input image signal. the

The display panel driving device according to the second aspect of the present invention is a display panel driving device for driving a display panel formed by a plurality of light-emitting elements including pixels arranged in a matrix form according to an input image signal, and the display panel driving device includes:

A driving voltage generation circuit, which provides a driving voltage for each of the plurality of light-emitting elements through a power line;

a current measuring part for obtaining a current value corresponding to each pixel by obtaining a current value flowing in the above-mentioned power supply line when each light emitting element is sequentially and independently emitted light at a timing of a light emitting time of each light emitting element, and store it in memory as the measured current value assigned to each pixel; and

and a driving voltage adjusting part for adjusting the voltage value of the driving voltage in such a manner that one of each measured light emission driving current value is equal to a predetermined reference current value. the

The display panel driving device according to the third aspect of the present invention is a display panel driving device for driving a display panel formed by a plurality of light-emitting elements including pixels arranged in a matrix according to an input image signal, and the display panel driving device includes:

A driving voltage generation circuit, which provides a driving voltage for each of the plurality of light-emitting elements through a power line;

a current measuring part for obtaining a current value flowing in the above-mentioned power supply line while causing each light emitting element to emit light sequentially and independently at the timing of the light emitting time of each light emitting element, thereby obtaining a current value corresponding to each pixel, and store it in memory as the measured current value assigned to each pixel;

a driving voltage adjusting part, which is used to adjust the voltage value of the above-mentioned driving voltage in such a way that one of each measured light-emitting driving current value is equal to a predetermined reference current value;

luminance correction means for obtaining luminance correction by correcting a luminance level represented by pixel data corresponding to each pixel of the above-mentioned input image signal by the above-mentioned measured current value of one pixel based on the above-mentioned pixel data stored in the above-mentioned memory the pixel data for ; and

The light-emitting driving part is used to make the above-mentioned light-emitting element emit light only during the image display light-emitting period in each frame period corresponding to the above-mentioned input image signal, and the period corresponding to the brightness-corrected pixel data.

Moreover, the display panel driving method according to the second aspect of the present invention is a display panel driving method for driving a display panel formed of a plurality of light-emitting elements including pixels arranged in a matrix form according to an input image signal, and the above-mentioned display panel driving method includes the following steps :

a current measuring step of obtaining a current value flowing in the above-mentioned power supply line while making each light-emitting element emit light independently sequentially with the timing of the light-emitting time of each light-emitting element, thereby obtaining a current value corresponding to each pixel; and

A driving voltage adjusting step of adjusting the voltage value of the above-mentioned driving voltage in such a manner that one of each measured light emitting driving current value is equal to a predetermined reference current value. the

Moreover, the display panel driving method according to the third aspect of the present invention is a display panel driving method for driving a display panel formed by a plurality of light-emitting elements including pixels arranged in a matrix form according to an input image signal, and the above-mentioned display panel driving method includes the following steps :

Obtaining the current value flowing in the above-mentioned power line while making each light-emitting element emit light independently at the timing of the light-emitting time of each light-emitting element, thereby obtaining the current value corresponding to each pixel;

Obtaining luminance-corrected pixel data by correcting the luminance level represented by the pixel data corresponding to each pixel of the input image signal by the above-mentioned measured current value of one of the above-mentioned pixel data stored in the above-mentioned memory; and

The above-mentioned light-emitting element is made to emit light only during an image display light-emitting period in each frame period corresponding to the above-mentioned input image signal, and at a period corresponding to the brightness-corrected pixel data. the

A display panel driving device according to a fourth aspect of the present invention is a driving device for a display panel having a plurality of pixel portions arranged therein, each pixel portion including a series circuit of a light emitting element and a switching element, and the driving device is configured to operate according to an input image signal. driving a display panel comprising: a driving voltage generator applying a driving voltage to a series circuit of each of the plurality of pixel parts; measuring the series circuit applied from the driving voltage generator to each of the plurality of pixel parts A current measuring part of a current value; an offset current component corresponding to a leakage current of the display panel is added to the current supplied by the driving voltage generator, and the series connection of each of the plurality of pixel parts The circuit provides a current supply part for synthesizing current; by separately turning on the switching element of each of the plurality of pixel parts, when the light emitting element of each of the plurality of pixel parts is sequentially made to emit light individually, in a memory control section that stores, in a memory, a measured current value measured by the current measuring section in light emission timing corresponding to each of the plurality of pixel portions; A luminance corrector that corrects the light emission luminance output by the light emitting device of each of the plurality of pixel portions by one of the values. the

A driving method according to a fourth aspect of the present invention is a display panel driving method for a display panel having a plurality of pixel portions arranged in a matrix, each pixel portion including a series circuit of a light-emitting element and a switching element, the driving method being used to operate according to Inputting an image signal to drive the display panel includes: applying an output driving voltage of a driving voltage generator to a series circuit of each of the plurality of pixel parts; The additional value obtained by the offset current component of the leakage current of the display panel is added to the series circuit of each of the plurality of pixel parts; A current value of a series circuit; stored in a memory when sequentially causing the light emitting element of each of the plurality of pixel portions to emit light individually by separately turning on the switching element of each of the plurality of pixel portions A measured current value obtained by measuring an output current value from the drive voltage generator in a light emission timing corresponding to each of the plurality of pixel portions; and based on a value corresponding to the measured current value stored in the memory One of which modifies the luminance of light emitted by the light emitting device of each of the plurality of pixel portions. the

Brief description of the drawings

Fig. 1 shows the schematic diagram of the composition of active matrix driving type EL display device;

Figure 2 shows an example diagram of the internal structure of an EL unit E comprising a pixel;

Fig. 3 shows the structural representation of active matrix drive type EL display device according to the present invention;

Fig. 4 shows the schematic diagram of the embodiment of the internal structure of electric current detection circuit 2;

FIG. 5 shows an embodiment of a light-emitting driving form, wherein the driving includes dividing a frame light-emitting period into three subframes SF1 to SF3;

Fig. 6 is a flow chart introducing the luminescence drive current measurement program executed by the drive control circuit 4;

FIG. 7 is a flow chart introducing the brightness correction value generation program executed by the drive control circuit 4;

FIG. 8 shows a diagram of a light-emitting driving form, wherein a light-emitting driving current measurement period HT is provided in one frame display period;

Figure 9 shows a schematic diagram of an embodiment of a current detection circuit 2 with a driving voltage generating circuit specially provided for each color;

FIG. 10 shows a schematic diagram of an embodiment of a current detection circuit 2 with a driving voltage generating circuit specially provided for each screen area in the display panel 10;

Fig. 11 shows the structural representation of another active matrix driven EL display device according to the present invention;

Fig. 12 shows the schematic diagram of the embodiment of the internal structure of electric current detection circuit 2;

Fig. 13 has introduced the flow chart of the driving voltage setting program carried out by the driving control circuit 4;

FIG. 14 shows an embodiment of a display panel 10 with an EL unit EX for obtaining a reference current value I _REF ;

Figure 15 shows a structural diagram embodying the display device of the present application;

Fig. 16 shows the structural diagram of the current detection circuit and the current supply circuit in the device shown in Fig. 15;

Figure 17 shows a flow chart of the leakage current cancellation program;

Figure 18 shows an example diagram of the leakage current cancellation process;

Fig. 19 shows another example of the structure of the current detection circuit and the current supply circuit in the device shown in Fig. 15;

Figure 20 shows another example of the structure of the current detection circuit and the current supply circuit in the device shown in Figure 15;

Figure 21 shows a flow chart of the light-emitting drive current measurement program;

Figure 22 shows a flow chart of the brightness correction value generation program; and

Fig. 23 shows a flowchart of the drive voltage setting program. the

Invention in detail

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. the

FIG. 3 shows a schematic structural view of an electroluminescent active matrix driven type EL display device (hereinafter referred to as an EL display device) according to the present invention.

As shown in Figure 3, the EL display device includes a driving voltage generating circuit 1, a current detecting circuit 2, a multiplier 3, a driving control circuit 4, a scanning line driver 5, a data line driver 6, an operating unit 7, and a light emitting driving current memory 8 , non-light emitting current value register 9A, reference current value register 9B and display panel 10 . the

The display panel 10 is composed of an anode power supply line 16, a cathode power supply line 17, and a screen having n horizontal scanning lines _A1 to A _n and m data lines _B1 to _Bm intersecting each other. Also, the drive voltage Vc is applied to the anode power supply line 16, and the ground potential GND is applied to the cathode power supply line 17. In addition, EL units _E1,1 to _En,m having pixels are formed at each intersection of the scanning lines _A1 to _An and the data lines _B1 to _Bm in the above-described display panel 10. The internal structure of the EL unit E is the same as that described in Fig. 2, so it will not be described here.

The driving voltage generating circuit 1 generates the above-mentioned DC driving voltage Vc, and applies it to the anode power line 16 of the display panel 10 through the current detecting circuit 2 . the

The current detection circuit 2 detects the current flowing through the anode power supply line 16 , and supplies a current value data signal CD indicating the detected current value to the drive control circuit 4 . For example, as shown in FIG. 4 , the current detection circuit 2 includes a resistor R1 connected between the drive voltage generation circuit 1 and the anode power supply line 16 of the display panel 10 , a measurement switch SW, and an A/D converter AD. When the current detection enable signal CE provided by the drive control circuit 4 is at a logic level 1, the measurement switch SW remains off, and when the provided current detection enable signal CE is at a logic level 0, the switch SW is turned on, so that The two ends of the resistor R1 are shorted. That is, when the measurement switch SW is turned off, the current detection circuit 2 is in the detection mode, and supplies the voltage generated across the resistor R1 according to the current value to the A/D converter AD. Next, the A/D converter AD supplies the result obtained by converting the voltage generated across the resistor R1 into a digital value to the drive control circuit 4 as a current value data signal CD. the

Then, the multiplier 3 is sequentially supplied with pixel data PD for each pixel according to the image signal carrying the image to be displayed on the display panel 10 . The pixel data PD describe the display brightness level of each pixel. The multiplier 3 multiplies the supplied pixel data PD of each pixel by the luminance correction value K provided by the drive control circuit 4 to obtain luminance corrected pixel data LD, which is then supplied to the drive control circuit 4 . That is, each time the pixel data PD of each of the EL units E1,1 to _En,m including the pixels of the display panel ₁₀ is sequentially input, the drive control circuit 4 reads in the previously measured value from the light emission drive current value memory 8. The current value of each pixel is measured, and the brightness correction value K is generated according to these measured current values, and provided to the multiplier 3 . The operation of measuring the current value of each pixel and generating the brightness correction value will be described in detail below.

The operation unit 7 receives the actions of the user and provides corresponding command signals to the drive control circuit 4 . For example, the operating unit 7 provides a power-on signal ON to the drive control circuit 4 according to a power-on operation command issued by the user, so as to initialize the display operation of the display panel 10 . Likewise, the operating unit 7 provides a power-off signal OFF to the driving control circuit 4 according to a power-off operation command issued by the user, so as to terminate the display operation of the display panel 10 . Furthermore, the operating unit 7 provides the drive control circuit 4 with a brightness correction control signal LAD according to a brightness correction command issued by the user. the

According to the above-mentioned power-on signal ON, the drive control circuit 4 generates the above-mentioned brightness correction value K (as described below), and controls the gradation of the display panel 10 that should display half-tone (half-tone) brightness according to the above-mentioned brightness-corrected pixel data LD drive. The hierarchical driving in the display panel 10 can be realized by any type of hierarchical method, and here we will introduce an embodiment using the sub-frame method. the

In the sub-frame method, a frame display period is subdivided into N sub-frames, wherein different light-emitting periods are assigned to different sub-frames. Intermediate luminance is realized in (2 ^N + 1) steps according to the luminance level represented by the pixel data, and by determining subframe combinations to realize light emission. Through this sub-frame method, the drive control circuit 4 provides the scan line driver 5 and the data line driver 6 with various drive control signals for driving the display panel 10 .

The operation of the scan line driver 5 and the data line driver 6 will be described below as an embodiment, wherein one frame display period is divided into three subframes SF1 to SF3 , as shown in FIG. 5 . the

The scan line driver 5 selectively applies scan pulses to each of the scan lines A1 to _An of the display panel ₁₀ during each of the three subframes SF1 to SF3 shown in FIG. 5 . Simultaneously, the data line driver 6 applies m luminance-corrected pixel data LD corresponding to each of m pixels in each scan line to each of the data lines _B1 to _Bm in synchronization with the application timing of the above-mentioned scan pulses. Each of the pixel data pulses DP ₁ to DP _m . The pixel data pulse DP has a high voltage pulse in case the EL unit E emits light during the subframe, and a low voltage pulse (for example, 0 volts) in the case of no light emission. Now, the EL cell E is connected to the scanning line A to which the scanning pulse is applied, and becomes a writing target of pixel data. In response to the scan pulse, the FET 11 in the EL unit E to which pixel data is written is turned on, and the pixel data pulse DP supplied through the data line B is applied to the gate G of the FET 12 and the capacitor 13, respectively. According to the pulse voltage of the pixel data pulse DP, the FET 12 generates an emission driving current (a current determined by the impedance of the EL element 15 ), and supplies it to the EL element 15 . That is, if the high-voltage pixel data pulse DP is supplied to the EL element 15, the above-mentioned light emission driving current causes it to be placed in a light emitting state. If a low voltage pixel data pulse DP is provided, it is placed in a non-emission state. Now, if the EL element 15 is supplied with a high voltage pixel data pulse DP during the subframe SF1 of FIG. 5, the EL element 15 keeps emitting light during the period "1". Also, if the EL element 15 is supplied with the high voltage pixel data pulse DP during the subframe SF2, the EL element 15 keeps emitting light during the period "2". If the EL element 15 is supplied with the high voltage pixel data pulse DP during the subframe SF3, the EL element 15 keeps emitting light during the period "4".

Therefore, for example, if light is emitted only during subframe 3 of subframes SF1 to SF3, light is emitted only in period "4" during a display period of one frame, and human eyes perceive brightness corresponding to light emission period "4" . Moreover, if light is emitted during the subframes SF1 and SF3, light is emitted only in the period "1"+"4"="5" during one frame display period, and human eyes perceive the brightness corresponding to the light emission period "5" . Likewise, if light is emitted during subframes SF2 and SF3, light is emitted only in the period "2"+"4"="6" during one frame display period, and human eyes perceive the brightness corresponding to the light-emitting period "6" . the

Therefore, when the display panel 10 is driven using the three sub-frames shown in FIG. 5, 9 levels of intermediate brightness can be realized. the

On the other hand, the driving control circuit 4 responds to the above-mentioned power-off signal OFF, and executes the light-emitting driving current measurement procedure introduced in FIG. 6 . the

In FIG. 6, first, the drive control circuit 4 supplies the scan line driver 5 and the data line driver 6 with a drive control signal to turn off the FETs 12 of all the EL elements _E1,1 to _En,m (step S1). Then, the drive control circuit 4 provides the current detection circuit 2 with a current detection enable signal CE of logic level 1 (step 2). Accordingly, the current detection circuit 2 detects a voltage generated between both ends of the resistor R1 according to the current flowing in the anode power supply line 16 , and supplies a current value data signal CD having a detected voltage value to the drive control circuit 4 . That is, when the operation of all the EL elements _E1,1 to _En,m is interrupted, the current flowing in the anode power supply line 16 is detected. Next, drive control circuit 4 stores the current value indicated by current value data signal CD in non-emission current value register 9A as the non-emission current value flowing to display panel 10 in the non-display mode (step 3). Next, the drive control circuit 4 stores "1" as an initial row number in a row number register (not shown in the figure), and stores "1" as an initial column number in a column number register (not shown in the figure) ( Step 4). Next, the driving control circuit 4 provides a driving control signal to the scanning line driver 5 and the data line driver 6, and the driving control signal is only used to drive the EL units E _1,1 to _En,m corresponding to those stored in the row number register X. The EL elements EX _{,Y of the row number and the column number stored in the column number register Y} emit light (step S5). When step S5 is performed, the scanning line driver 5 applies a scanning pulse only to the scanning line _AX designated by the row number stored in the row number register X among the scanning lines _A1 to _An . Meanwhile, the data line driver 6 supplies high voltage pulses only to those data lines B _Y specified by the column numbers stored in the column number register Y among the data lines _B1 to B _m , and supplies low voltages to the other groups in the data lines B Pixel data pulse DP. Through the above-described operation, the light emission driving current flows only in the EL element ₁₅ formed in the EL unit _EX,Y among the EL units E1,1 to _En,m to cause the EL element 15 to emit light. Therefore, only the current consumed by the EL element 15 formed by the EL unit _EX,Y flows through the anode power supply line 16 . Now, the current detection circuit 2 supplies the drive control circuit 4 with the current value data signal CD indicating the current flowing in the anode power supply line 16 .

Here, the drive control circuit 4 obtains the current value represented by the above-mentioned current value data signal CD, and stores it as a measured current value in address [X, Y] of the light emission drive current value memory 8 (step 6). Next, the drive control circuit 4 increments the column number stored in the column number register Y by 1 (step S7). Next, the drive control circuit 4 checks whether the column number stored in the column number register Y is greater than the last column number m (step 8). In step 8, if the column number stored in the column number register Y is not greater than the last column number m, the drive control circuit 4 jumps back to the above step S5, and repeats the operations described here. the

By repeating the above steps S5 to S8, the EL flowing through all the EL elements _E1,1 to _En,m formed in the scanning line AX specified by the line number stored in the line number register _X is measured one by one. The light emission drive current of the element 15 is stored in the light emission drive current value memory 8.

On the other hand, in the above step S8, if the column number Y stored in the column number register is verified to be greater than the last column number m, the drive control circuit 4 only adds 1 to the row number X stored in the row number register ( Step S7), and rewrite the column number Y stored in the column number register by writing 1 (step S9). That is, by performing Step 9, the scanning line AX formed by the group of EL elements E whose light emission drive current is to be measured moves to the next scanning line AX ₊₁ . The drive control circuit 4 checks whether the row number X stored in the row number register is greater than the last row number n (step 10). In step 8, if the row number X stored in the row number register is not greater than the last row number n, the drive control circuit 4 jumps back to the above step S5, and repeats the operations described here.

By repeating the above steps S5 to S10, the light emission drive currents flowing through the EL elements 15 formed in all the EL units _E1,1 to _En,m forming the display panel 10 are measured, and the measurement results are stored in the The light-emitting driving current value memory 8.

Moreover, in the above-mentioned step S10, if the row number X stored in the row number register is greater than the last row number n, the drive control circuit 4 sets the current value of each pixel stored in the above-mentioned light-emitting drive current value memory 8 The minimum current value is searched for and stored in the reference current value register 9B (step S11). Next, the drive control circuit 4 provides the current detection circuit 2 with a current detection enable signal CE whose logic level is 0 (step S12 ). Thus, both ends of the resistor R1 provided in the current detection circuit 2 are short-circuited, so that the driving voltage Vc generated by the driving voltage generating circuit 1 is directly applied to the anode power supply line 16 . After completing the above step S12, the drive control circuit 4 exits the light-emitting drive current measurement program and returns to the main program (not shown in the figure). the

The above-described luminescence drive current measurement procedure is executed in response to the current shut-off operation of the user stopping the display operation in the display panel 10 . That is, although the display operation based on the image data has not been completed, if light is emitted independently, the light emission drive current flowing into the EL element 15 of each pixel is measured, and the measurement result is stored in the light emission drive current value memory 8 as a measured current value. the

Now, when the user uses the operation unit 7 to perform a power-on operation to initialize the display operation of the display panel 10 , the operation unit 7 provides the drive control circuit 4 with a power-on signal ON. In response to the power-on signal ON, the drive control circuit 4 executes the luminance correction value generation program introduced in FIG. 7 to generate a luminance correction value K. the

In FIG. 7, first, the drive control circuit 4 checks whether or not pixel data PD has been input; this check is repeated until pixel data PD is effectively input (step S21). In step 21, when pixel data PD is input, drive control circuit 4 reads out a measured current value corresponding to input pixel data PD from light emission drive current value memory 8 (step S22). Next, the drive control circuit 4 determines a brightness correction value K obtained by dividing the reference current value I _REF stored in the reference current value register 9B by the above-mentioned measured current value (step S23). This K value is supplied to the multiplier 3 (step S24). Thus, the multiplier 3 generates brightness-corrected pixel data LD for each pixel by the following expression:

LD = pixel data PD · brightness correction value K

=Pixel data PD (reference current value I _REF /measurement current value)

Next, the drive control circuit 4 checks whether the power-off signal OFF has been supplied by the operation unit 7 (step S25). In step S25, if the power-off signal OFF is not provided, the drive control circuit 4 returns to execute the above-mentioned step S21, and repeats the operations described here. On the other hand, if the power-off signal OFF has been provided in step S25, the drive control circuit 4 exits the luminance correction value generation program, and turns to execute the luminescence drive current measurement program introduced in FIG. 6 . the

By executing the above-mentioned luminance correction value generating procedure, when the light emission driving current measured for each pixel becomes larger relative to the above-mentioned reference current value I _REF , the luminance correction value is generated so that the EL element in the EL unit corresponding to each pixel The light emitting period of 15 is shorter than the period indicated by the pixel data PD. Thereby, brightness-corrected pixel data is obtained as a product of the pixel data PD provided for the pixel and the brightness correction value K described above.

For example, if the measured current value of the EL element 15 formed in the EL unit _E1,1 is 120% of the reference current value, the luminance correction value is 0.83, and the luminance correction pixel data LD will be the _{1, the pixel data PD of 1} is multiplied by 0.83. If the measured current value of the EL element 15 formed in the EL unit E1, ₂ is 110% of the reference current value, the luminance correction value is 0.91, and the luminance correction pixel data LD will be provided for this EL unit E1 _{, 2} The pixel data PD of ₂ is multiplied by 0.91.

That is, the luminance correction of the pixel data PD is performed so that the light emission period in each frame of the EL element 15 with a large light emission drive current is shorter than the light emission period in each frame of the EL element 15 with a small light emission drive current. . That is, the luminous brightness of the EL element 15 with a large luminescence drive current is greater than that of the EL element 15 with a small luminescence drive current, when only the number of luminescence periods in each frame is reduced according to the pixel data PD corresponding to the EL element 15, the screen Brightness can have a uniform display. the

Thereby, even if luminance variation occurs in each EL element corresponding to each pixel as a result of driving the display panel for an extended time, display of a high-quality image without luminance unevenness can be obtained.

In addition, in the above-described embodiment, the minimum current value among the measured current values of each pixel stored in the light emission drive current value memory 8 is used as the reference current value I _REF , but the maximum current value may also be used as the reference current value I REF . _REF . Now, as introduced in step S11 shown in FIG. 6, the drive control circuit 4 searches for the maximum current value among the measured current values of each pixel stored in the above-mentioned light emission drive current value memory 8, and uses this value as The reference current value is stored in the reference current value register 9B. Thereby, the luminance is corrected for the pixel data PD such that the light emission period of each frame of the EL element 15 is extended to such an extent that the light emission drive current thereof is smaller than that of the reference EL element 15 having the maximum light emission drive current. In this case, the brightness correction value K is always greater than 1. Now, in order to determine the luminance-corrected pixel data LD which is the product of the luminance correction value K and the input pixel data, a product of a predetermined coefficient (not greater than 1) is further added. For example, if the coefficient is 0.7, the brightness-corrected pixel data LD can be obtained by the following expression:

LD=Pixel data PD·0.7·Brightness correction value K

=Pixel data PD 0.7 (reference current value I _REF /measurement current value)

In the above-mentioned embodiments, the actually measured value of the light-emitting driving current of each pixel is stored in the light-emitting driving current value memory 8 as the measured current value, but it may also be stored in the light-emitting driving current value memory 8 related to each pixel. The difference between the measured current value and the aforementioned reference current value I _REF is stored.

Furthermore, in the display panel 10, in addition to the light emission drive current itself flowing through the EL element 15, some minute current is consumed. In this case, in order to accurately measure the light emission drive current itself flowing through the EL element 15, the result of subtracting the non-light emission current value stored in the non-light emission current value register 9A from the current value detected by the current detection circuit 2 may also be It is stored in the light emission drive current value memory 8 as the final measured current value. the

Moreover, if the current value of the above-mentioned measurement current obtained by measuring the light emission driving current flowing through each pixel is outside a specific current value range, the drive control circuit 4 considers that the EL unit including the pixel corresponding to the measurement current value E is faulty, and "0" is supplied to the multiplier 3 as the luminance correction value K corresponding to this pixel. Now, the pixel data PD is multiplied by 0, the resulting luminance-corrected pixel data LD becomes 0, and the EL element 15 corresponding to this pixel is permanently turned off. That is, the drive control circuit 4 prohibits the light emitting operation of the EL unit E corresponding to the defective pixel.

Still in the above-mentioned embodiment, in response to the user's power-off operation, the light-emitting driving current measurement program shown in FIG. 6 is executed only once, but it may also be executed repeatedly at regular intervals. Also, the timing to start execution of the above-described light emission drive current measurement program is not necessarily limited to the user's power-off operation. For example, if the EL display device shown in FIG. 3 is integrated into any type of portable information terminal device, such as a mobile phone, etc., the above-mentioned light-emitting driving current measurement procedure can also be carried out when the portable information terminal device is charging, or when the portable information terminal device is turned off The display surface of the panel 10 is displayed. Furthermore, it may be compulsorily executed in response to a user's brightness correction command. Here, as required by the brightness correction instruction device, if the operating unit 7 provides the brightness correction control signal LAD to the drive control circuit 4, the drive control circuit 4 responds to the brightness correction control signal LAD and executes the light-emitting drive current measurement program, as shown in Figure 6 shown. Also, the above-mentioned light-emitting driving current measurement procedure may be performed during the light-emitting driving current measurement period HT in each frame except the above-mentioned subframes SF1 to SF3, as shown in FIG. 8 . That is, the light emission driving current measurement procedure is performed to measure the light emission driving current of each pixel in periods other than the pixel display light emission period including the subframes SF1 to SF3 in each frame. the

In the above-described embodiments, the current detection circuit 2 that actually detects the light-emitting driving current is provided between the driving voltage generating circuit 1 and the anode power supply line 16, however, in the case where the driving voltage generating circuit 1 includes a plurality of independent driving voltage generating circuits Next, a current detection circuit may also be provided for each drive voltage generation circuit. the

For example, in FIG. 9, a red emission driving voltage generating circuit 1R, a green emitting driving voltage generating circuit 1G, and a blue emitting driving voltage generating circuit 1B are independently provided as driving voltage generating circuits. The red light emission driving voltage generating circuit 1R supplies a driving voltage to each of the EL elements E emitting red light among the EL elements _E1,1 to _En,m in the display panel 10 through the anode power supply line 16R. The green light emission driving voltage generating circuit 1G supplies a driving voltage to each of the EL elements E emitting green light among the EL elements _E1,1 to _En,m in the display panel 10 through the anode power supply line 16G. The blue light emission driving voltage generation circuit 1B supplies a driving voltage to each of the EL elements E emitting blue light among the EL elements _E1,1 to _En,m in the display panel 10 through the anode power supply line 16B. By providing the current detection circuit 2R between the red light emission driving voltage generation circuit 1R and the anode power supply line 16R, the current detection circuit 2G between the green light emission driving voltage generation circuit 1G and the anode power supply line 16G, and the blue light emission driving voltage A current detection circuit 2B is provided between the generation circuit 1B and the anode power supply line 16B to detect the current respectively.

Also, as shown in FIG. 10 , a driving voltage generating circuit 1 a for display in the first region and a driving voltage generating circuit 1 b for display in the second region may be independently provided as the driving voltage generating circuit 1 . The driving voltage generation circuit 1a of the first area supplies a driving voltage to each EL unit E including pixel display in the first screen area GM1 through the anode power supply line 16a. The driving voltage generation circuit 1b of the second area supplies a driving voltage to each EL unit E including pixel display in the second screen area GM2 through the anode power supply line 16b. This can be detected by providing a current detection circuit 2a between the driving voltage generating circuit 1a and the anode power supply line 16a of the first region and a current detecting circuit 2b between the driving voltage generating circuit 1b and the anode power supply line 16b of the second region, respectively. current. In addition, one display panel can be divided not only into two areas as shown in Fig. 10, but also into several areas arbitrarily according to the scale and detection speed of the current detection circuit. the

As described above, in the first aspect of the present invention, the driving current value for causing each light emitting element including the pixel to emit light sequentially individually and sequentially is measured, and then, each corresponding to the input pixel data is Pixel-relative input pixel data corrected for brightness. the

Thus, according to the first aspect of the present invention, even if luminance variation occurs in each EL element corresponding to each pixel as a result of prolonged driving of the display panel, display of a high-quality image without luminance irregularity can be obtained. the

Other embodiments of the present invention will be described in detail below with reference to the accompanying drawings. the

FIG. 11 is a schematic diagram showing another structure of an electroluminescent display device (hereinafter referred to as an EL display device) using the display panel driving method for displaying images according to the present invention. the

The EL display device shown in FIG. 11 is similar to that shown in FIG. 3 except that a variable drive generating circuit 1A is used instead of the driving voltage generating circuit 1 here. the

The variable driving voltage generating circuit 1A generates the above-mentioned DC driving voltage Vc having a voltage value specified by the driving voltage specifying signal VD supplied from the driving control circuit 4, and supplies it to the anode power supply line 16 of the display panel 10. the

The current detection circuit 2 detects the current flowing through the anode power supply line 16 , and supplies a current value data signal CD indicating the detected current value to the drive control circuit 4 . As shown in FIG. 12, the current detection circuit 2, similar to FIG. 4, includes a resistor R1 connected between the variable drive voltage generating circuit 1 and the anode power supply line 16 of the display panel 10, a measurement switch SW, and an A/D converter. AD, so its operation will not be explained here. the

Drive control circuit 4 carries out gradation display by, for example, the sub-field method shown in FIG. The drive voltage setting procedure. the

In FIG. 13, first, the drive control circuit 4 checks whether the reference current value I _REF stored in the above reference current value register 9B is smaller than a predetermined upper limit current value I _MAX (step S31). The upper limit current value I _MAX is the upper limit value of the range of light emission driving current for causing the EL element 15 to emit light such that the required minimum luminance is secured while not exceeding a predetermined power consumption value. In the above step S31, if it is verified that the reference current value I _REF is not smaller than the upper limit current value I _MAX , the drive control circuit 4 takes the result obtained by subtracting the prescribed voltage value α from the voltage value specified by the previous drive voltage specifying signal VD as The driving voltage designates a new designated voltage value of the signal VD, which is then applied to the variable driving voltage generating circuit 1 (step S32). By executing step S32, the variable drive voltage generation circuit 1 applies the drive voltage Vc reduced only by the portion corresponding to the prescribed voltage value α to the anode power supply line 16. Next, the drive control circuit 4 re-executes the light emission drive current measurement routine introduced in FIG. 6 (step S33). That is, in step S32, in the case of subtracting the result of the part corresponding to the prescribed voltage value α from the driving voltage Vc applied to the anode power supply line 16, re-executing the operation in the EL elements _E1,1 to _En,m Measurement of the light emission drive current of each EL element 15. After completing the above step S33, the driving control circuit 4 returns to execute the above step S31, and repeats the process described here. That is, the drive control circuit 4 continues to reduce the drive voltage Vc applied to the anode power line 16 by the prescribed voltage value α until the reference current value I _REF is smaller than the upper limit current value I _MAX .

In the above step S31, if it is verified that the reference current value I _REF is smaller than the upper limit current value I _MAX , then the drive control circuit 4 checks whether the reference current value I _REF is larger than the specified lower limit current value I _MIN (step S34 ). The lower limit current value I _MIN is the minimum light emission drive current value for causing the EL element 15 to emit light with a required minimum luminance. In the above step S34, if it is checked that the reference current value I _REF is not greater than the lower limit current value I _MIN , the drive control circuit 4 takes as The driving voltage designates a new designated voltage value of the signal VD, which is then applied to the variable driving voltage generating circuit 1 (step S35). By executing step S35, the variable drive voltage generation circuit 1 applies the drive voltage Vc increased by only the portion corresponding to the prescribed voltage value α to the anode power supply line 16. After step S35 is completed, the driving control circuit 4 continues to re-execute the light-emitting driving current measurement procedure of step S33. That is, in the case of adding the result corresponding to the prescribed voltage value α from the drive voltage Vc applied to the anode power supply line 16, each EL element in the EL elements _E1,1 to _En,m is newly executed. 15. Measurement of luminescence drive current. After completing the above step S33, the driving control circuit 4 returns to execute the above step S31, and repeats the process described here. That is, the drive control circuit 4 continues to increase the drive voltage Vc applied to the anode power line 16 by the specified voltage value α until the reference current value I _REF is greater than the lower limit current value I _MIN .

In the above step S34, when it is verified that the reference current value I _REF is greater than the lower limit current value I _MIN and the reference current value I _REF remains within the range defined by the lower limit current value I _MIN and the upper limit current value I _MAX , then the drive control circuit 4 Exit the driving voltage setting program, and return to execute the main program (not shown in the figure).

Thus, by executing the above-described drive current voltage setting procedure, the minimum light emission drive current value among the light emission drive currents flowing through each of the EL elements 15 in the EL units _E1,1 to _En,m becomes such that the EL elements 15 The driving voltage Vc is adjusted in the manner of the light-emitting driving current value required to emit light within the desired brightness range.

Therefore, even if a change in the internal resistance value of the EL element 15 occurs as a result of, for example, a change in the manufacturing process, a change in the ambient temperature, or due to accumulation of luminous life, etc., the brightness level of the entire screen of the display panel 10 can be maintained at the desired level. within the desired brightness range. the

Also, in the above-described embodiment, the current detection circuit 2 that actually detects the light-emitting driving current is provided between the variable driving voltage generating circuit 1A and the anode power supply line 16, however, if the variable driving voltage generating circuit 1 includes a plurality of independent The variable driving voltage generation circuit, as shown in FIG. 9 , can also provide a current detection circuit for each variable driving voltage generation circuit. the

Moreover, as shown in FIG. 10, the driving voltage generating circuit 1a for display in the first area and the driving voltage generating circuit 1b for displaying in the second area and the variable voltage shown in FIG. 11 can be independently provided. Driving voltage generating circuit 1A. the

Furthermore, in the above-described embodiment, the driving voltage setting routine described in FIG. 13 is executed after the light emission driving current measurement routine described in FIG. 6 is executed, but it may also be repeatedly executed at regular intervals. the

Also, in the above-mentioned drive current measurement procedure, the minimum measured current value among the measured current values in each of the EL elements 15 in the EL units _E1,1 to _En,m is kept at the minimum current value defined by the lower limit current value I _MIN The driving voltage Vc is adjusted in a manner defined by the upper limit current value I _MAX . However, the adjustment of the drive voltage Vc may also be performed in such a manner that the average value of these measured current values is kept within the range defined by the lower limit current value I _MIN and the upper limit current value I _MAX . In this case, the drive control circuit 4 determines the average value of the measured current values for each pixel stored in the light emission drive current value memory 8, and executes steps S31 to S35 in FIG. 13 using this value as the reference current value I _REF operation.

In the present invention, if necessary, the minimum measured current value of each EL unit E _1,1 to E _n,m or the average value of each measured current is equal to a predetermined reference current value (from the lower limit current value I _MIN to the upper limit current value I _MAX ) to adjust the driving voltage Vc.

In setting the above-mentioned reference current value I _REF , an average value of light emission current values measured for a specified plurality of EL elements 15 in all EL units E forming the display panel 10 may also be used as the reference current value I _REF . In addition, the reference current value I _REF may also be a light emission current value measured for a specific EL element E in the display panel 10 . In addition, the specific EL unit may be one of the EL units E _1,1 to E _n,m , or an EL unit EX (having an internal structure shown in FIG. 2 ) specially provided for obtaining the reference current value I _REF , As shown in Figure 14. In this case, the EL unit EX receives the driving voltage supplied through the anode power supply line 16 like the EL units E _1,1 to _En,m . In order to obtain the light emission driving current value of the EL unit EX as the reference current value I _REF , the driving control circuit 4 provides current measurement signals to the data line driver 6 and the scanning line driver 5 . In response to the current measurement signal, the data line driver 6 supplies pixel data pulses to the EL unit EX through the data line B _EX , and the scan line driver 5 supplies scan pulses to the EL unit _EX through the scan line A EX. Thus, a light emission drive current flows through the EL element 15 in the EL unit EX to cause light emission, and a light emission drive current flows through the anode power supply line 16 . Now, the current detection circuit 2 detects the light emission driving current flowing through the anode power supply line 16 and supplies the current value data signal CD representing the current value to the driving control circuit 4 . The drive control circuit 4 obtains the current value represented by the current value data signal CD, and stores it in the reference current value register 9B as a reference current value I _REF .

Thus, as described in the second and third aspects of the present invention, each light emission drive current value sequentially flowing through each light emitting element containing the pixel to cause the pixel to emit light individually is measured for each pixel [for further use]. According to the input pixel data, the luminance correction of the input pixel data is performed based on the luminescence driving current value related to the pixel, and the luminance provided to each light emitting element is adjusted in such a manner that one value of each measured luminescence driving current value is equal to a predetermined reference current value. The voltage value of the driving voltage. the

Thus, with the second and third aspects of the present invention, it is possible to prevent irregularities in brightness from occurring in the screen, and to keep the brightness level of the entire screen within a certain range at all times. the

Another embodiment of the present invention will be described with reference to the drawings. the

FIG. 15 shows a display device as another embodiment of the present invention. The display device consists of a display panel 21, a controller 22, a pixel current value memory 23, a data signal supply circuit 24, a scan pulse supply circuit 25, a current detection circuit 26, a power supply circuit 27, a current supply circuit 28 and a current summation circuit 29. Component composition. the

The display panel 21 includes a plurality of data lines _Y1 to _Ym (m is an integer greater than one), a plurality of scan lines _X1 to _Xn (n is an integer greater than one), and a plurality of power lines Z1 to Zn. As shown in FIG. 15, a plurality of scanning lines _X1 to _Xn and a plurality of power supply lines Z1 to Zn are arranged in parallel to each other. A plurality of data lines _Y1 to _Ym are cross-arranged with a plurality of scan lines _X1 to _Xn and a plurality of power supply lines Z1 to Zn. The respective pixel parts _PL1,1 to PLn _{, m} are arranged at intersections of the plurality of data lines _Y1 to Ym and the plurality of scan lines _X1 to _Xn , thereby forming a matrix type display panel. The power supply lines Z1 to Zn are connected to each other to form a single power supply line Z, which is then connected to the current summation circuit 29 . Each of the plurality of pixel sections PL _1,1 to PL _n,m has the structure shown in FIG. 2 .

The display panel 21 is connected to a scan pulse supply circuit 25 through scan lines _X1 to _Xn , and is also connected to a data signal supply circuit 24 through data lines _Y1 to _Ym . The controller 22 generates scan control signals and data control signals to drive the display panel under grayscale driving control according to incoming image signals. The scan control signal is supplied to the scan pulse generation circuit 25 , and the data control signal is supplied to the data signal supply circuit 24 .

The scan pulse supply circuit 25 is connected to the scan lines _X1 to _Xn , and supplies scan pulses to the scan lines _X1 to _Xn in a predetermined order according to a scan control signal.

The data signal supply circuit 24 is connected to the data lines _Y1 to _Ym , and supplies a pixel data pulse to a pixel portion to be driven into a light-emitting state among pixel portions on the scan line to which the scan pulse is applied through the data lines.

The gray scale driving scheme of the display panel 21 is the same as the scheme introduced with reference to FIG. 2, so the description will not be repeated. the

When the display panel is driven using three subframes as shown in FIG. 4, half tones of eight-level grayscale can be displayed with different combinations of the three subframes. the

In the pixel memory 23, the respective pixel current values of the pixel portions PL _1,1 to PL _n,m are written as data by the controller. The procedure of this write operation is described below.

The current detection circuit 26 detects the value of the current output to the power line Z from the power supply circuit 27 . The current supply circuit 28 sets an offset current value based on the current value detected by the current detection circuit 26 , and supplies the offset value of the detected current value to the current summation circuit 29 . the

As shown in FIG. 16 , the current detection circuit 26 includes a current measurement circuit 31 and an A/D converter 32 . The current supply circuit 28 includes a judgment circuit 36 , a D/A converter 37 and a current generation circuit 38 , still as shown in FIG. 16 . the

A current measurement circuit 31 is inserted between the power supply circuit 27 and the current summation circuit 29 . The current measuring circuit 31 has a resistance R and a switch SW connected in parallel so that when the switch SW is closed, the current from the power supply circuit 27 is supplied to the power supply circuit through the switch SW, and when the switch SW is opened, the current from the power supply circuit 27 is passed through the resistance R is supplied to the power supply circuit. The switching state of the switch SW is controlled by the controller 22 . The current measurement circuit 31 outputs a voltage corresponding to the value of the current flowing through the resistance R, that is, the voltage across the resistance R. the

The A/D converter 32 converts the output voltage of the current measurement circuit 31 into a digital signal, and supplies the digital signal to the controller 22 and the judgment circuit 36 . The judging circuit 36 judges whether or not the leakage current value indicated by the digital signal output from the A/D converter 32 is within a predetermined range. In addition, the judgment circuit 36 sets the offset current value according to the judgment result. The offset current value specified by the judgment circuit 36 is output to the D/A converter 37 in the form of a digital signal. The D/A converter 37 converts the digital signal into a voltage signal in analog form, and supplies the analog signal to the current generation circuit 38 . The output voltage of the D/A converter 37 is controlled by instructions from the controller 22 . The current generation circuit 38 , which is a V/I conversion circuit that converts a voltage signal into a current, thereby outputs an offset current having a value specified by the judgment circuit 36 . the

The current summation circuit 29 adds the currents output by the current measurement circuit 31 and the current generation circuit 38, and supplies the total current to the power supply lines Z1 to Zn. the

The controller 22 executes a leakage current elimination program and a light emission drive current measurement program. The leakage current elimination program is a program for measuring the current flowing in the display panel 21 as a leakage current when light emission driving is stopped in all the pixel sections PL _1,1 to PL _n,m , and is used to drive the current generation circuit 38 to output The current corresponding to the leakage current. The light emission driving current measurement program is a program for measuring the driving current of each of the pixel sections PL _1,1 to PL _n,m . Although the timing of executing these programs does not need to be set at any specific point in time, it can be performed, for example, when the power of the display device is turned off, when no image data is input, or between one subfield and the next subfield executed at intervals.

In the leakage current canceling process, as shown in FIG. 17, the controller 22 puts the display panel 21 in a state where all the pixel portions PL _1,1 to PL _n,m thereon stop the light emitting drive (step S41). Specifically, the controller 22 stops generating the aforementioned scan control signal and data control signal. Then, the controller 22 sets the output voltage of the D/A converter 37 to 0V so that the offset current value is equal to zero (step S42). When the output voltage of the D/A converter 37 is 0V, the output of the offset current from the current generating circuit 38 is thereby turned off. Furthermore, the controller 22 sets the switch of the current measurement circuit 31 in the OFF position (step S43).

In this control state, the output voltage (power supply voltage) Vc of the power supply circuit 27 is added between the power supply lines Z1 to Zn and the ground of the display panel 21 through the current measurement circuit 31 and the resistance R of the current summation circuit 29, thereby displaying Leakage current flows through the board 21 . The output voltage of the current measurement circuit 31 is converted into a digital value by the A/D converter 32 and supplied to the judgment circuit 36 . The controller 22 drives the judgment circuit 36 to make a judgment whether the leakage current value indicated by the digital signal output by the A/D converter 32 is within a predetermined range (step S44). As a result of judgment by the judgment circuit 36, if the leakage current value is larger than the predetermined range, a digital signal corresponding to a current increment equal to the predetermined current value Ir is output to the D/A converter 37 (step S45). The digital signal may be supplied to the D/A converter 37 by one of the controller 22 and the judgment circuit 36 . The D/A converter 37 converts the supplied digital signal into an analog signal, and supplies the analog signal to the current generating circuit 38 . The current generation circuit 38 increases the current value by a predetermined current value Ir, and outputs the increased current. The output current of the current generation circuit 38 is supplied to the current summation circuit 29 . The current output from the power supply circuit is reduced by the current value Ir by way of the output current of the current generating circuit 38 . That is, the value of the current flowing from the current summation circuit 29 to the display panel 21 itself remains unchanged. the

When the judging circuit 36 judges that the measured leakage current is within the predetermined range, the controller 22 causes the current generating circuit 38 to hold the output current value at that time as the offset current value (step S46).

FIG. 18 shows how the measured leakage current changes before the current value of the measured leakage current reaches a predetermined range. The leakage current value measured for the first time is the value of the actual leakage current flowing in the display panel 21 . For the first time, no current is output from the current generating circuit 38 . The leakage current value of the second time is a value obtained by reducing the current value Ir from the actual leakage current value. In the second time, the output current value of the current generating circuit 38 is equal to Ir. In this way, the j-th leakage current value is a value obtained by subtracting the current value (j-1)Ir from the actual leakage current value I ₀ . The judging circuit 36 judges whether the current value satisfies 0≦I ₀ -(j-1)Ir≦Ia, where 0 and Ia are end values of a predetermined range of current values 0 to Ia.

In FIG. 18, the sixth measured leakage current value is a value obtained by subtracting the current value 5Ir from the actual leakage current value, and is expressed as I ₀ -5Ir. In the sixth measurement, the output current value of the current generating circuit 38 was 5Ir. The leakage current value of the sixth measurement is in the predetermined range 0 to Ia. The output current value of the current generating circuit 38 is held as an offset current.

As shown in FIG. 19 , the current supply circuit 28 is composed of an analog operation circuit 39 and a current generation circuit 38 . The analog operation circuit 39 calculates the voltage level supplied to the current generation circuit 38 from the voltage representing the leakage current value output by the current measurement circuit 31 . In short, the analog operation circuit 39 drives the current generating circuit 38 to output the current (j-1)Ir so as to satisfy the condition: 0≤I ₀ −(j-1)Ir≤Ia.

As shown in FIG. 20 , the current supply circuit 28 may be constituted only by the current generation circuit 38 . In the current supply circuit 28 in FIG. 20, its output current value can be adjusted manually. Using this characteristic, the output current of the current generating circuit 38 is manually adjusted so that the measured leakage current value output by the current measuring circuit 31 becomes a current value in a predetermined range of 0 to Ia. the

In addition, in each of the embodiments shown in FIGS. 16, 19 and 20, the case where the EL elements constituting the light emitting elements of the pixel portions PL _1,1 to PL _n,m of the display panel emit light of the same color has been described. . In the case of emitting light to generate a plurality of colors, for example, RGB (red, green, and blue), the driving voltage VC may be different for each light emitting color. In this case, the power supply circuit 27, the current detection circuit 26, and the current supply circuit 28 may be provided for each pixel portion respectively having a different emission color.

After holding the output current of the current supply circuit 28 as the offset current value in the above-mentioned leakage current elimination procedure, the controller 22 executes the light emission drive current measurement procedure for each of the pixel sections PL _1,1 to PL _n,m .

As shown in FIG. 21, the controller 22 first stores "1" as the initial row number in the row number register X (not shown), and stores "1" as the initial column number in the column number register Y (not shown). (step S51). Subsequently, the controller 22 supplies the scan pulse supply circuit 25 and the data signal supply circuit 24 with a method for making only the row numbers stored in the row number register X and the row numbers stored in the pixel portions PL _1,1 to PL _n,m corresponding to The driving control signal for the pixel part PL _{X, Y of the column number in the column number register Y} to emit light (step S52). As a result of execution of step S52, the scan pulse supply circuit 25 supplies scan pulses only to the scan line _XX indicated by the row number stored in the row number register X among the scan lines _X1 to _Xn . At the same time, the data signal supply circuit 24 only provides a data signal of a low level (for example, ground potential) to the data line Y _Y indicated by the column number stored in the column number register Y among the data lines _Y1 to _Ym , and at the same time The remaining data lines other than the data line Y _Y provide a potential of a high voltage. Through the above-described processing operations, the light emission drive current flows only through the EL elements in the pixel portions PL X, _Y of the pixel portions PL _1,1 to PL _n,m , so that the EL elements emit light. Accordingly, only the light emission drive current consumed by the EL elements in the pixel portions PL _{X, Y} flows through the power supply lines Z _Y and Z. The current detection circuit 26 supplies the controller 22 with a current value data signal CD representing the current value flowing through the power line Z.

In this process, the controller 22 obtains the current value represented by the above-mentioned current value data signal CD, and stores it in the address [X, Y] in the pixel current value memory 23 (step S53). Then, the controller 22 increments the column number stored in the column number register Y by one (step S54). Subsequently, the controller 22 judges whether or not the column number stored in the column number register Y is greater than the last column number m (step S55). If it is judged in step S55 that the column number stored in the column number register Y is not greater than the last column number m, the controller 22 returns to execute the above step S52, and repeats the above operations. the

By repeatedly executing the above-mentioned steps S52 to S55, the EL elements flowing through the pixel portions PL _1,Y to PL _{n, Y} located on the scanning line X Y indicated by the row number stored in the row number register X are sequentially measured respectively. The light-emitting driving current is stored in the light-emitting driving current memory 8 .

In step S55, if it is detected by the controller 22 that the column number stored in the column number register Y is greater than the last column number m, the row number stored in the row number register X is increased by one, and stored in the column number register Y The column number of is rewritten to 1 (step S56). Briefly, by performing step S56, the pixel portion as the measurement object of the light emission driving current moves from the scanning line XX to the pixel portion on the next scanning line XX ₊₁ . The controller 22 also judges whether or not the row number stored in the row number register X is greater than the last row number n (step S57). If it is determined in step S57 that the row number stored in the row number register X is not greater than the last row number n, the controller 22 returns to step S52 to repeat the above operations.

By repeatedly executing steps S52 to S57, light emission drive currents are measured for all the EL elements in the pixel portions PL _1,1 to PL _n,m formed in the display panel 21, and the measurement results are stored in pixel current values respectively corresponding to the pixels. in memory 23.

If it is judged in the above step S57 that the row number stored in the row number register X is greater than the last row number n, the controller 22 searches for the smallest current value among the respective pixel current values of the pixels stored in the above-mentioned pixel current memory 23, And the searched current value is stored in an internal register (not shown) as a typical current value (step S58). Then, the controller 22 performs a control operation to close the switch SW in the current measurement circuit 31 (step S59). the

By this operation, both ends of the resistance R provided in the current measuring circuit 31 are short-circuited, so that the driving voltage Vc generated by the power supply circuit 27 is directly applied to the power supply line Z. After step S59 is executed, the controller 22 exits the light-emitting driving current measurement program, and returns to execute the main program (not shown). the

As described above, the luminescence drive current measurement program is executed in response to the user's closing operation to stop displaying images on the display panel 21 . In other words, the light emission driving current flowing is measured while each EL element in the pixel portions PL _1,1 to PL _n,m is individually driven to emit light during a period in which the display operation of image data is not performed. The measurement results are stored in the pixel current value memory 23 . Since the measurement of the pixel current value is performed with the leakage current component almost removed, high-precision pixel current value measurement can be performed for each of the pixel portions PL _1,1 to PL _n,m . In addition, when the above-mentioned leakage current elimination program and light emission drive current measurement program are used, offset current values are set for the display panel respectively, and high-precision pixel current value measurement can be performed for each of the pixel portions PL _1,1 to PL _n,m .

Then, to start the display of the display panel 21, the luminance correction value generation program shown in FIG. 22 is executed to generate the above-mentioned luminance correction value K corresponding to the pixel data in the input image data for each pixel. the

The controller 22 first judges whether image data is input, and obtains pixel data PD (step S61). Step S61 is repeatedly executed until the pixel data PD is obtained. Then, the controller 22 reads out the pixel current value corresponding to the pixel data PD from the pixel current value memory 23 (step S62). Then, the controller obtains the result of dividing the typical value stored in the internal register by the above-mentioned pixel current value as the brightness correction value K (step S63), and calculates the brightness correction pixel data LD by multiplying the pixel data PD by the brightness correction value K (step S64). In step S64, brightness-corrected pixel data LD is obtained by the following formula. the

LD = pixel data PD · brightness correction value K

= Pixel data PD (typical current value/pixel current value)

The controller 22 repeats the process of steps S61 to S64 until the display of the screen is turned off, so as to obtain the brightness-corrected pixel data LD of each pixel. the

By executing the above-mentioned luminance correction value generation program, the larger the light emission drive current measured with each pixel is relative to the above-mentioned typical current value, the greater the light emission period of the EL element in the pixel portion corresponding to the pixel is expressed by the pixel data of the pixel. The brightness correction value K is obtained in a way that the cycle is shorter. Thus, the result obtained by multiplying the above-mentioned luminance correction value K by the pixel data PD supplied corresponding to the pixel is used as the luminance correction pixel data LD. the

For example, if the current value of the pixel portion PL _1,1 is 120% of the above typical value, the luminance correction value K is 0.83, so that the value obtained by multiplying the pixel data supplied to the pixel portion PL _1,1 by 0.83 is used as the luminance The pixel data LD is corrected. Likewise, when the current value of the pixel portion PL _{1, 2} is 110% of the above-mentioned typical value, the luminance correction value K is equal to 0.91, so that the value obtained by multiplying the pixel data supplied to the pixel portion PL _1, 2 by 0.91 is used as the luminance Correction data LD.

That is, the luminance correction affects the pixel data PD in such a way that the light emission period in each frame of the pixel portion of the EL element with a large drive current is smaller than that of the EL element with a small drive current. In short, although the luminance of light emitted by an EL element having a larger drive current is greater, by shortening the light emission period in one frame corresponding to the pixel data PD of the EL element having a large drive current to an extent to overcome the increase in luminance , so that the appearance brightness of the EL element in the screen is uniform. the

Even if the luminance of light emitted from each EL element varies from device to device due to long-term use of the display panel 21, high-quality display free from luminance unevenness can be obtained according to the present invention. the

In the above-described embodiments, the minimum current value among the pixel current values stored in the pixel current value memory 23 is used as the typical current value. However, the maximum current value can also be used as a typical current value. In this case, in step S58 shown in FIG. 21 , the controller 22 searches for the maximum current value from the respective pixel current values of the pixels stored in the pixel current memory 23, and stores the searched current value in the internal register, as a typical current value. Through this process, when using the EL element with the largest luminescence drive current as a reference, luminance correction affects pixel data in such a way that the smaller the luminescence drive current is, the longer the luminescence period of the EL element is. The brightness correction value K always has a value greater than one. Therefore, when the brightness correction value K is multiplied by the pixel data PD to obtain the brightness correction pixel data LD, the result of the first multiplication is multiplied by a predetermined coefficient less than 1. For example, when the predetermined coefficient is 0.7, the luminance-corrected pixel data LD is calculated according to the following formula. the

LD=Pixel data PD·0.7·Brightness correction value K

= Pixel data PD 0.7 (typical current value/pixel current value)

Furthermore, in the above-described embodiment, the pixel current value actually measured for each pixel is stored in the pixel current value memory 23 . However, the difference between the pixel current value corresponding to each pixel and the above-mentioned typical current value may also be stored in the pixel current value memory 23 . the

A scheme in which the controller 22 continues to execute the driving voltage setting program shown in FIG. 23 after executing the light emission driving current measuring program may also be adopted. the

In FIG. 23, first, the controller 22 performs a judgment of whether the typical current value I _REF stored in the above-mentioned internal register is smaller than a predetermined upper limit current value I _MAX (step S71). The upper limit current value I _MAX is an upper limit value of a light emission drive current for causing the EL element in the pixel portion to emit light with a luminance higher than a minimum necessary level while keeping power consumption below a predetermined value. If it is judged in step S71 that the typical current value I _REF is not less than the predetermined upper limit current value I _MAX , the controller 22 subtracts the drive voltage designation signal obtained by subtracting the predetermined voltage value α from the voltage value designated by the previous drive voltage designation signal VD VD is supplied to the power supply circuit 27 (step S72). As a result of the execution of step S72, the power supply circuit 27 applies the drive voltage Vc reduced by the predetermined voltage value α to the power supply line Z. Then, the controller 22 executes the above-mentioned light emission drive current measurement routine again (step S73). This means that, by performing step S72, under the condition that the predetermined voltage α is subtracted from the drive voltage Vc applied to the power supply line Z, each EL element in the pixel portions PL _1,1 to PL _n,m is re-measured separately. Lighting drive current. After step S73 is executed, the controller 22 returns to step S71 to repeat the above process. Briefly, the controller 22 repeats the above process to reduce the driving voltage Vc applied to the power line Z by a predetermined value α until the typical current value I _REF is smaller than the upper limit current value I _MAX .

In the above step S71, if it is judged that the typical current value I _REF is smaller than the upper limit current value I _MAX , the controller 22 judges whether the typical current value I _REF is larger than the lower limit current value I _MIN (step S74 ). The lower limit current value I _MIN is the lower limit value of the light emission drive current for causing the EL element to emit light at the minimum necessary luminance level. If it is judged in step S74 that the typical current value I _REF is not greater than the lower limit current value I _MIN , then the controller 22 provides a driving voltage designation signal VD to the power supply circuit 27 (step S75), the driving voltage designation signal VD is passed through the front It is obtained by adding a predetermined voltage value α to the voltage value specified by the driving voltage specifying signal VD for a short time. As a result of executing step S75, the power supply circuit 27 applies the drive voltage Vc increased by the predetermined voltage value α to the power supply line Z. After executing step S75, the controller 22 continues to execute the light-emitting driving current measurement program in step S73. This means that, by performing step S72, with the predetermined voltage α added to the drive voltage Vc applied to the power supply line Z, each EL element in the pixel portions PL _1,1 to PL _n,m is re-measured separately. Lighting drive current. After step S73 is executed, the controller 22 returns to step S71 to repeat the above process. Briefly, the controller 22 repeats the process, reducing the driving voltage Vc applied to the power line Z by a predetermined voltage value α until the typical current value I _REF is greater than the lower limit current value I _MIN .

In the above step S74, if it is judged that the typical current value I _REF is greater than the lower limit current value I _MIN , which means that the typical current value I _REF is within the range between the lower limit current value I _MIN and the upper limit current value I _MAX , then the controller 22 Exit the driving voltage setting program, and return to execute the main program (not shown).

As described above, by executing the drive voltage setting program, the drive voltage is adjusted so that the smallest one of the light emission drive currents flowing through each of the pixel portions PL _1,1 to PL _n,m is equal to the drive voltage within the desired luminance range. The light-emitting driving current required for the EL element to emit light.

Also, an upper limit can be set for the driving voltage Vc in order to protect the display panel. the

With the above characteristics, even if the internal resistance of the EL element fluctuates due to temperature variation or accumulation of light emission periods, the brightness level of the entire display area of the display panel 21 can be maintained. the

As described above, according to the present invention, even if the display device is used for a long time, it is possible to display an image with high quality without luminance fluctuation.

Claims (67)

1. A display panel driving device, used to drive a display panel formed by a plurality of light-emitting elements supporting pixels arranged in a matrix form, comprising: a driving voltage generation circuit, which provides a driving voltage to each of the plurality of light emitting elements through a power line; a current measuring part for measuring the value of the current flowing in the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements, thereby obtaining the light emitting element the current value of each of the above; when all the light-emitting elements formed in the display panel are extinguished, the value of the current flowing in the power supply line is measured as the non-light-emitting current value, and the current value will be obtained from the current value The result obtained by subtracting the non-light emitting current value is stored in the memory as the measured current value corresponding to each pixel; a luminance correcting section for correcting luminance represented by the pixel data corresponding to each pixel of the input image signal based on the measured current value of one of the pixels corresponding to the pixel data stored in the memory level to obtain brightness-corrected pixel data; and The light-emitting drive unit is used to make the light-emitting element emit light in a period corresponding to the brightness-corrected pixel data only during an image display light-emitting period in each frame period of the input image signal. 2. The display panel driving device according to claim 1, wherein said current measuring section, in a period other than said image display light emitting period, at a timing of causing said light emitting elements to emit light for each of said light emitting elements While sequentially emitting light independently, the value of the current flowing through the power line is measured as the current value. 3. The display panel driving device according to claim 1, wherein said current measuring section measures a current while causing said light emitting elements to emit light sequentially and independently at a timing of a light emitting time of each of said light emitting elements in response to a luminance correction instruction. The value of the current passing through the power line is used as the current value. 4. The display panel driving device according to claim 1, wherein said current measuring part comprises: Scanning the light-emitting driving part, so that the light-emitting elements sequentially emit light independently; a current detection circuit that detects the value of the current flowing in the power line; and A means for sequentially obtaining, as the current value, the value of the current detected by the current detection circuit at the timing of the light emission time of each of the light emitting elements. 5. The display panel driving device according to claim 4, wherein said current detection circuit comprises: a resistor connected in series to said power line; a means for outputting a voltage value developed across said resistance as a digital value capable of being used as said current value; and A switch is used to short the resistors across when not measuring. 6. The display panel driving device according to claim 1, wherein said brightness correction means comprises: a luminance correction value calculating section for calculating a luminance correction value such that the luminance correction value is determined from the measured current value assigned to one of the pixels corresponding to the pixel data; and A multiplier for obtaining a product of multiplying the pixel data by the brightness correction value as the brightness correction pixel data. 7. The display panel driving device according to claim 6, wherein said luminance correction value calculation means obtains said luminance correction value which becomes smaller as said measured current value increases. 8. The display panel driving device according to claim 6, wherein said luminance correction value calculation means obtains said luminance correction value which becomes larger as said measured current value decreases. 9. The display panel driving device according to claim 1 , comprising a section for detecting defective pixels corresponding to said measured current values stored in said memory outside a specified current value range. measured current value; where The light emission driving section includes a section that prohibits light emitting operation of those light emitting elements corresponding to the defective pixel. 10. The display panel driving device according to claim 4, wherein said driving voltage generating circuit comprises: a first driving voltage generation circuit that supplies a driving voltage to each of the light emitting elements formed in the display panel that emits red light through a first power line; a second driving voltage generating circuit that supplies a driving voltage to each of the light emitting elements formed in the display panel that emits blue light through a second power supply line; and a third driving voltage generating circuit that supplies a driving voltage to each of the light emitting elements formed in the display panel that emits green light through a third power supply line; and wherein the current detection circuit includes a first current detection circuit for detecting a current flowing in the first power line; a second current detection circuit for detecting a current flowing in the second power line; A third current detection circuit for the current flowing in the third power line. 11. The display panel driving device according to claim 4, wherein said driving voltage generating circuit comprises: When the display panel is divided into a plurality of regions, a first driving voltage generation circuit that supplies a driving voltage to the light emitting elements supporting image display in the first screen region through a first power line; and a second driving voltage generation circuit that supplies a driving voltage to the light emitting elements that support image display in a second screen area different from the first area through a second power supply line; and Wherein the current detection circuit includes at least a first current detection circuit for detecting the current flowing in the first power line; and a second current detection circuit for detecting the current flowing in the second power line . 12. A method for driving a display panel, for driving a display panel formed by a plurality of light-emitting elements supporting pixels arranged in a matrix, comprising: a current measuring step of measuring the value of the current flowing in the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements, thereby obtaining the light emitting element each of the current value; when all the light-emitting elements formed in the display panel are extinguished, the value of the current flowing in the power supply line is measured as the non-light-emitting current value, and, from the current value The result obtained by subtracting the non-light emitting current value is stored in the memory as a measured current value corresponding to each pixel; a luminance correction step of obtaining luminance-corrected pixel data by correcting a luminance level represented by the pixel data corresponding to each pixel of the input image signal based on the measured current value of one of the pixels corresponding to the pixel data ;as well as The light-emitting driving step is used to make the light-emitting element emit light only in a period corresponding to the brightness-corrected pixel data during an image display light-emitting period in each frame period of the input image signal. 13. The display panel driving method according to claim 12, wherein said current measuring step includes, in a period other than said image display light emission period, causing said light emitting elements to emit light at a light emission time of each of said light emitting elements While sequentially and independently emitting light at the timing of each other, the value of the current flowing through the power line is measured as the current value. 14. The display panel driving method according to claim 12, wherein said current measuring step includes, in response to a luminance correction command, while causing said light emitting elements to emit light sequentially and independently at a timing of a light emitting time of each of said light emitting elements, A value of a current flowing through the power supply line is measured as the current value. 15. The display panel driving method according to claim 12, wherein said brightness correction step comprises: a brightness correction value calculation step of determining a brightness correction value from the measured current value assigned to one of the pixels corresponding to the pixel data; and The multiplication step is used to determine the product of the obtained pixel data and the brightness correction value as the brightness correction pixel data. 16. The display panel driving method according to claim 15, wherein said luminance correction value calculating step obtains said luminance correction value which becomes smaller as said measured current value increases. 17. The display panel driving method according to claim 15, wherein said luminance correction value calculating step obtains said luminance correction value which becomes larger as said measured current value decreases. 18. The display panel driving method according to claim 12, comprising a step for detecting a defective pixel corresponding to a pixel located outside a specified current value range among said measured current values stored in said memory. said measured current value; and Wherein the light emitting driving step includes prohibiting the light emitting operation of the light emitting element corresponding to the defective pixel. 19. A display panel driving device for driving a display panel formed by a plurality of light-emitting elements supporting pixels arranged in a matrix according to an input image signal, comprising: a driving voltage generation circuit, which provides a driving voltage to each of the plurality of light emitting elements through a power line; a current measuring part for measuring the value of the current flowing in the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements, thereby obtaining the light emitting element the current value of each of the above; when all the light-emitting elements formed in the display panel are extinguished, the value of the current flowing in the power supply line is measured as the non-light-emitting current value, and the current value will be obtained from the current value A result obtained by subtracting the non-light emitting current value is stored in a memory as a measured current value corresponding to each pixel; and a driving voltage adjusting section for adjusting a voltage value of the driving voltage in such a manner that one of the measured current values is set as a predetermined reference current value. 20. The display panel driving device according to claim 19 , further comprising a light emitting display part for making said light emitting element correspond to said input image only during an image display light emitting period in each frame period of said input image signal glow during the period of the signal; Wherein the current measuring means measures the current flowing through the power line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements in a period other than the image display light emitting period. The current value is used as the current value. 21. The display panel driving device according to claim 19, wherein said current measuring section measures current while causing said light emitting elements to emit light sequentially and independently at the timing of light emitting time of each of said light emitting elements in response to a brightness correction instruction. The value of the current passing through the power line is taken as the current value. 22. The display panel driving device according to claim 19, wherein said current measuring part comprises: Scanning light-emitting drive components, used to make the light-emitting elements sequentially and independently emit light; a current detection circuit for detecting a value of current flowing in the power line; and A means for obtaining, as the current value, a current value detected by the current detection means at the timing of light emission time of each of the light emitting elements. 23. The display panel driving device according to claim 22, wherein said current detection circuit comprises: a resistor connected in series to said power line; means for outputting a voltage value generated across the resistance as a digital value capable of being used as the current value; and A switch, when not measuring, is used to create a short circuit across the resistor. 24. The display panel driving device according to claim 19, wherein said driving voltage adjusting part comprises: means of searching for a minimum current value as a minimum measured current value among said measured current values stored in said memory; and means for adjusting a voltage value of the drive voltage in such a manner that the minimum measured current value has the same current value as the reference current value. 25. The display panel driving device according to claim 19, wherein said driving voltage adjusting section includes a section for having the same current as an average value of said measured current values stored in said memory and said reference current value The voltage value of the driving voltage is adjusted in a manner of value. 26. The display panel driving device according to claim 19, wherein said driving voltage adjusting part comprises: a means for adjusting the voltage value of the drive voltage in such a manner that the measured current value corresponding to a predetermined one of the pixels among the measured current values stored in the memory , or an average value corresponding to a predetermined plurality of measured current values of the pixels has the same current value as the reference current value. 27. The display panel driving device according to claim 22, wherein said driving voltage generating circuit comprises: a first driving voltage generation circuit, configured to provide a driving voltage to each of the light emitting elements supporting red light among the light emitting elements formed in the display panel through a first power line; a second driving voltage generating circuit for supplying a driving voltage to each of the light emitting elements supporting blue light emission among the light emitting elements formed in the display panel through a second power supply line; and a third driving voltage generating circuit for supplying a driving voltage to each of the light emitting elements emitting green light among the supporting light emitting elements formed in the display panel through a third power supply line; and Wherein the current detection circuit includes: a first current detection circuit for detecting a current flowing in the first power supply line; a second current detection circuit for detecting a current flowing in the second power supply line; and a third current detection circuit for detecting a current flowing in the second power supply line; for detecting the current flowing in the third power line. 28. The display panel driving device according to claim 22, wherein said driving voltage generating circuit comprises: A first driving voltage generating circuit, when the display panel is divided into a plurality of regions, for providing a driving voltage to each of the light emitting elements supporting image display in at least the first screen region through a first power line; and a second driving voltage generation circuit for supplying a driving voltage to each of the light emitting elements supporting image display in a second screen area different from the first area through a second power supply line; and wherein The current detection circuit includes: at least a first current detection circuit for detecting current flowing in said first power line; and The second current detection circuit is used to detect the current flowing in the second power line. 29. A display panel driving method for driving a display panel formed by a plurality of light-emitting elements supporting pixels arranged in a matrix according to an input image signal, comprising: a current measuring step of measuring the value of the current flowing in the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements, thereby obtaining the light emitting element the current value of each of them; when all the light-emitting elements formed in the display panel are extinguished, measure the value of the current flowing in the power supply line as the non-light-emitting current value, and subtract the current value from The obtained result of the non-emission current value is stored in a memory as a measured current value corresponding to each pixel; and a driving voltage adjusting step of adjusting a voltage value of the driving voltage in such a manner that one of the measured current values is set as a predetermined reference current value. 30. The display panel driving method according to claim 29, further comprising a light-emitting display step for making said light-emitting element correspond to said input image only during an image display light-emitting period in each frame period of said input image signal Lights up during the period of the signal; Wherein the current measuring step includes, in a period other than the image display light emitting period, measuring the current flowing through the light emitting elements while sequentially making the light emitting elements emit light independently at the timing of the light emitting time of each of the light emitting elements. The value of the current of the power line is used as the current value. 31. The display panel driving method according to claim 29, wherein said current measuring step includes, in response to a luminance correction instruction, while causing said light emitting elements to emit light sequentially and independently at a timing of a light emitting time of each of said light emitting elements, A value of a current flowing through the power supply line is measured as the current value. 32. The display panel driving method according to claim 29, wherein said driving voltage adjusting step further comprises: a step of searching for a minimum current value among the measured current values as the minimum measured current value; and The step of adjusting the drive voltage value in such a way that the minimum measured current value has the same current value as the reference current value. 33. The display panel driving method according to claim 29, wherein said driving voltage adjusting step includes adjusting a voltage value of said driving voltage in such a manner that an average value of said measured current value has the same current value as said reference current value A step of. 34. The display panel driving method according to claim 29, wherein said driving voltage adjusting step comprises, to correspond to a measured current value of a predetermined pixel among said measured current values, or to correspond to a predetermined plurality of pixel measured currents The step of adjusting the voltage value of the driving voltage in such a manner that the average value of the value has the same current value as the reference current value. 35. A display panel driving device for driving a display panel formed by a plurality of light-emitting elements supporting pixels arranged in a matrix form according to an input image signal, comprising: a driving voltage generating circuit for providing a driving voltage to each of the plurality of light emitting elements through a power line; a current measuring part for measuring the value of the current flowing in the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements, thereby obtaining the light emitting element the light emitting current value of each of them; when all the light emitting elements formed in the display panel are extinguished, the value of the current flowing in the power supply line is measured as the non-light emitting current value, and the light emitting current value is The result obtained by subtracting the non-light emitting current value is stored in the memory as the measured current value corresponding to each pixel; a driving voltage adjusting part for adjusting the driving voltage value in such a manner that one of the measured current values is set as a predetermined reference current value; a luminance correcting section for correcting luminance represented by the pixel data corresponding to each pixel of the input image signal based on the measured current value of the one pixel corresponding to the pixel data stored in the memory level, to obtain brightness corrected pixel data; and A light-emitting drive unit, configured to make the light-emitting element emit light only in a period corresponding to the brightness-corrected pixel data during an image display light-emitting period in each frame period of the input image signal. 36. The display panel driving device according to claim 35, further comprising: a light-emitting display part, causing the light-emitting element to emit light only in a period corresponding to the input image signal during an image display light-emitting period in each frame period of the input image signal; Wherein said current measurement components include: A part for measuring the current flowing through the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements in a period other than the image display light emitting period The value of , as the light emitting current value. 37. The display panel driving device according to claim 35, wherein said current measuring part comprises: A means for measuring, as the light emitting current, the value of the current flowing through the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements in response to a brightness correction instruction. value. 38. The display panel driving device according to claim 35, wherein said current measuring part comprises: Scanning light-emitting drive components, used to make the light-emitting elements sequentially and independently emit light; a current detection circuit for detecting a value of current flowing in the power line; and A means for obtaining, as the light emission current value, a value of a current detected by the current detection means at the timing of light emission time of each of the light emitting elements. 39. The display panel driving device according to claim 38, wherein said current detection circuit comprises: a resistor connected in series to said power line; a means for converting a voltage value generated at both ends of the resistor by a current value flowing in the power supply line when the light emitting elements sequentially and independently emit light into a digital value used as the light emitting current value; and A switch that creates a short circuit across the resistor when not measuring. 40. The display panel driving device according to claim 35, wherein said luminance correction means comprises: a luminance correction value calculating section for determining a luminance correction value from the measured current value assigned to one of the pixels corresponding to the pixel data; and a multiplier for obtaining said luminance-corrected pixel data as a result of multiplying said pixel data by said luminance correction value. 41. The display panel driving device according to claim 40, wherein said luminance correction value calculation means obtains said luminance correction value which becomes smaller as said measured current value increases. 42. The display panel driving device according to claim 40, wherein said luminance correction value calculation means obtains said luminance correction value which becomes larger as said measured current value decreases. 43. The display panel driving device according to claim 35, comprising: a means for detecting, among the measured current values stored in the memory, a faulty pixel corresponding to a measured current value outside a specified range of current values; Wherein the light emission driving section includes a section that prohibits a light emitting operation of the light emitting element corresponding to the defective pixel. 44. The display panel driving device according to claim 35, wherein said driving voltage adjusting part comprises: a means for searching for a minimum current value among said measured current values stored in said memory as a minimum measured current value; and A means for adjusting the voltage value of the drive voltage in such a manner that the minimum measured current value has the same current value as the reference current value. 45. The display panel driving device according to claim 35 , wherein said driving voltage adjusting section includes an average value of each of said measured current values stored in said memory having the same current value as said reference current value. means for adjusting the voltage value of the drive voltage. 46. The display panel driving device according to claim 35, wherein said driving voltage adjusting part comprises: a means for adjusting the voltage value of the driving voltage in a manner corresponding to a measured current value of a predetermined one of the pixels among the measured current values stored in the memory, or An average value of measured current values corresponding to a predetermined plurality of pixels has the same current value as the reference current value. 47. The display panel driving device according to claim 38, wherein said driving voltage generating circuit comprises: a first driving voltage generation circuit, configured to provide a driving voltage to each of the light emitting elements supporting red light among the light emitting elements formed in the display panel through a first power line; a second driving voltage generating circuit for supplying a driving voltage to each of the light emitting elements supporting blue light emission among the light emitting elements formed in the display panel through a second power supply line; and a third driving voltage generation circuit for supplying a driving voltage to each of the light emitting elements supporting green light emission among the light emitting elements formed in the display panel through a third power supply line; and Wherein the current detection circuit includes: a first current detection circuit for detecting a current flowing in the first power supply line; a second current detection circuit for detecting a current flowing in the second power supply line; and a third current detection circuit for detecting a current flowing in the second power supply line; for detecting the current flowing in the third power line. 48. The display panel driving device according to claim 38, wherein said driving voltage generating circuit comprises: a first driving voltage generation circuit for supplying a driving voltage to each of the light emitting elements supporting image display in a first screen area of a screen of the display panel through a first power line; and a second driving voltage generation circuit for supplying a driving voltage to each of the light emitting elements supporting image display in a second screen area different from the first area through a second power supply line; and Wherein the current detection circuit includes a first current detection circuit for detecting the current flowing in the first power line; and a second current detection circuit for detecting the current flowing in the second power line. 49. A display panel driving method, driving a display panel formed by a plurality of light-emitting elements supporting pixels arranged in a matrix form according to an input image signal, comprising: a current measuring step of measuring the value of the current flowing in the power supply line while causing the light emitting elements to emit light sequentially and independently at the timing of the light emitting time of each of the light emitting elements, thereby obtaining the light emitting element the current value of each of the above; when all the light-emitting elements formed in the display panel are extinguished, the value of the current flowing in the power supply line is measured as the non-light-emitting current value, and the current value will be obtained from the current value A result obtained by subtracting the non-light emitting current value is stored in a memory as a measured current value corresponding to each pixel; and a driving voltage adjusting step of adjusting a voltage value of the driving voltage in such a manner that one of the measured current values is set as a predetermined reference current value; a luminance correcting step of correcting the pixel data represented by each pixel corresponding to the input image signal based on the measured current value of one of the pixels corresponding to the pixel data stored in the memory luminance level to obtain luminance-corrected pixel data; and The light-emitting driving step is used to make the light-emitting element emit light only in a period corresponding to the brightness correction pixel data during an image display light-emitting period in each frame period of the input image signal. 50. The display panel driving method according to claim 49, further comprising a light emitting display step for causing said light emitting element to correspond to said input image only during an image display light emitting period in each frame period of said input image signal emits light during the period of the signal; and Wherein the current measuring step includes, in a period other than the image display light emitting period, measuring the current flowing through the light emitting elements while sequentially making the light emitting elements emit light independently at the timing of the light emitting time of each of the light emitting elements. The value of the current of the power line is used as the current value. 51. The display panel driving method according to claim 49, wherein said current measuring step includes, in response to a luminance correction command, while causing said light emitting elements to emit light sequentially and independently at a timing of a light emitting time of each of said light emitting elements, A value of a current flowing through the power supply line is measured as the current value. 52. The display panel driving method according to claim 49, wherein said brightness correction step comprises: a luminance correction value calculating step of calculating a luminance correction value from the measured current value assigned to one of the pixels corresponding to the pixel data; and A multiplier for obtaining the product of the pixel data and the brightness correction value as the brightness correction pixel data. 53. The display panel driving method according to claim 52, wherein said luminance correction value correcting step obtains said luminance correction value which becomes smaller as said measured current value increases. 54. The display panel driving method according to claim 52, wherein said luminance correction value correcting step obtains said luminance correction value which becomes larger as said measured current value decreases. 55. The display panel driving method according to claim 49, further comprising the step of detecting, among said measured current values stored in said memory, a defective pixel corresponding to a measured current value located outside a specified current value range; Wherein the light emitting driving step includes the step of prohibiting the light emitting operation of the light emitting element corresponding to the defective pixel. 56. The display panel driving method according to claim 49, wherein said driving voltage adjusting step further comprises the following steps: searching for a minimum current value among the measured current values as the minimum measured current value; and The voltage value of the driving voltage is adjusted in such a manner that the minimum measured current value has the same current value as the reference current value. 57. The display panel driving method according to claim 49, wherein said driving voltage adjusting step includes adjusting a voltage value of said driving voltage in such a manner that an average value of said measured current value has the same current value as said reference current value A step of. 58. The display panel driving method according to claim 49, wherein said driving voltage adjusting step includes a step of adjusting a voltage value of said driving voltage in such a manner that in said measured current value stored in said memory A measured current value corresponding to a predetermined pixel, or an average value of measured current values corresponding to a predetermined plurality of pixels has the same current value as the reference current value. 59. A driving device for a display panel having a plurality of pixel parts arranged therein, each pixel part comprising a series circuit of a light emitting element and a switching element, the driving device for driving the display panel according to an input image signal, comprising: a driving voltage generator for applying a driving voltage to the series circuit of each of the plurality of pixel sections; a current measuring part for measuring a current value supplied from the drive voltage generator to the series circuit of each of the plurality of pixel sections; a current supply part for adding an offset current component corresponding to a leakage current of the display panel to the current supplied from the driving voltage generator, and supplying the series circuit of each of the plurality of pixel sections synthetic current; a memory control section that stores, as a measured current value, a result obtained by subtracting a non-light emitting current value from a current value obtained by separately turning on each of the plurality of pixel portions in the memory. a switching element, the current value measured by the current measuring means at a light emission timing corresponding to each of the plurality of pixel portions while sequentially causing the light emitting element of each of the plurality of pixel portions to emit light individually , the non-luminous current value is a non-luminous current value obtained by measuring the value of the current when all the light-emitting elements formed in the display panel are turned off; and A luminance corrector for correcting a light emission luminance output of the light emitting device of each of the plurality of pixel portions based on a measured current value corresponding to one stored in the memory. 60. The display panel driving apparatus according to claim 59, wherein when the light emitting devices of all the plurality of pixel portions are in the non-light emitting state, the offset current component has a selected value for controlling the output from the driving voltage generator output current. 61. The display panel driving apparatus according to claim 59, wherein said current supply part includes a readout and judgment part which reads out The current value output from the driving current generation part is used as the measured leakage current, and it is judged whether the measured leakage current is within a predetermined current range; and a controller is also included, when the read judgment part judges that the measured leakage current is within the predetermined current range Otherwise, the controller performs a control operation of increasing the output current of the current supply part, and causes the readout and judgment part to perform the readout operation and judgment operation again, and when the readout judgment part judges The controller holds an output current of the current supply part as a value of the offset current component when the measured leakage current is outside a predetermined current range. 62. The display panel driving apparatus according to claim 61, wherein said reading and judging section is a circuit that converts said measured leakage current value into digital data, and performs digital processing for said judging operation. 63. The display panel driving apparatus according to claim 61, wherein said reading and judging means is a circuit for performing analog processing on the basis of said measured leakage current value which has been read out for said judging operation. 64. The display panel driving apparatus according to claim 59, wherein said brightness modifier comprises: a luminance data corrector for correcting each pixel in the input video signal by the the brightness level represented by the pixel data, resulting in brightness corrected pixel data, and The light emitting driver is used to drive the light emitting element to emit light in an image display light emitting period in each frame period of the input video signal, wherein the period corresponds to the brightness correction pixel data. 65. The display panel driving apparatus according to claim 59, wherein said luminance corrector has a driving voltage adjuster for adjusting a voltage value of said driving voltage so as to set said measured current value as a predetermined reference voltage. 66. The display panel driving apparatus according to claim 59, wherein a driving voltage generator, said current measuring section, and said current supplying section are provided for each light emitting color of said light emitting element. 67. A display panel driving method for a display panel having a plurality of pixel sections arranged in a matrix, each pixel section including a series circuit of a light emitting element and a switching element for driving the display panel according to an input image signal, the Methods include: applying an output drive voltage of the drive voltage generator to the series circuit of each of the plurality of pixel sections; The series circuit of each of the plurality of pixel sections is supplied with an additional value obtained by adding a value corresponding to the Obtained by the offset current component of the leakage current of the display panel; measuring a current value supplied from the drive voltage generator to the series circuit of each of the plurality of pixel sections; A result obtained by subtracting a non-light emitting current value from a current value obtained by respectively turning on the switching elements of each of the plurality of pixel portions is stored in a memory as a measured current value. measuring the output current value from the drive voltage generator at a light emission timing corresponding to each of the plurality of pixel portions while sequentially causing the light emitting element of each of the plurality of pixel portions to emit light individually. Obtained, the value of the non-luminous current is obtained by measuring the value of the current when all the light-emitting elements formed in the display panel are turned off; and The light emission luminance output of the light emitting device of each of the plurality of pixel portions is corrected based on a corresponding measured current value stored in the memory.

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