JP2008152180A - Display device driving circuit, self-luminous display device, electronic apparatus, display device driving method, and computer program - Google Patents

Abstract

In a conventional method in which drivers are arranged on both sides of a data line, rising and falling characteristics can be improved, while cost and power consumption increase.
In a display device driving circuit for driving an active matrix driving type self-luminous display device, the signal voltage is from one or a horizontal scanning period before the writing timing of the signal voltage to be originally written to the end of the original writing period. It is equipped with a function to control the write signal of ON. Image correlation between adjacent scan lines is generally high. Therefore, the voltage change at the original write timing can be kept small.
[Selection] Figure 7

Description

  The invention described in this specification relates to a driving technique of an active matrix driving type self-luminous display device. Note that the present invention has aspects as a display device driving circuit, a self-luminous display device, an electronic apparatus, a display device driving method, and a computer program.

  The trend toward larger screens and higher definition of flat panel display devices is increasing. Along with this, signal delay with respect to the driving frequency of the panel display element and deterioration of the rising / falling characteristics (frequency characteristics) of the driving signal have become problems.

  FIG. 1 shows an example of drive signals of an active matrix drive type display device. FIG. 1 shows an example of a drive signal when the data line is driven from one side. As shown in FIG. 1, writing of the signal voltage Vin (FIG. 1A) to each pixel is performed by a write signal WS (FIG. 1B to FIG. 1) synchronized with the horizontal synchronization signal HS (FIG. 1E). (D)) are executed in sequence with the rise.

  By the way, in this driving method, the waveform of the signal voltage Vin becomes dull as the writing frequency increases (indicated by a broken line in FIG. 1A). For this reason, it is difficult to accurately write the signal voltage Vin to the capacitor in the display element.

Therefore, a method of driving the drive line from both sides has been proposed for the purpose of improving the rise / fall characteristics with respect to the drive frequency.
FIG. 2 shows a screen configuration example of the display device 1. As shown in FIG. 2, two data line drivers 5 are arranged on both upper and lower sides of the display panel 3.

The selection of the pixel 11 to which the signal voltage Vin is to be written is performed by the scanning line driver 7 that outputs the write signal WS.
JP 2005-345910 A

  However, the method of driving the data lines from the both sides by the two data line drivers 5 has a positive aspect that can improve the rising and falling characteristics, but has a negative aspect that increases the manufacturing cost and power consumption. Moreover, there is a negative aspect that the power consumption tends to increase as the drive frequency increases. Accordingly, there is a need for a proposal of a technology that is excellent in balance between improvement of various characteristics and cost.

  Therefore, the inventor, as a display device driving circuit for driving an active matrix drive type self-luminous display device, from one or several horizontal scanning periods before the writing timing of the signal voltage to be originally written to the end of the original writing period. Then, a device having a function of controlling a signal voltage write signal to be in an on state is proposed.

  In the present invention, the writing of the signal voltage is started one or several horizontal scanning periods before the original writing timing. As a result, only the difference from the signal voltage written to the previous horizontal line is written at the original write timing.

  This is because a high correlation is recognized between images adjacent in the vertical direction. As a result, at the original write timing, the write operation can be completed with only a slight voltage change. This means that the rising characteristic of the signal voltage with respect to the driving frequency can be improved.

  In addition, since there is no need to increase the number of data line drivers or overdrive, the power consumption of the invention can be reduced if the driving frequency is the same as the existing driving method. In the method of the invention, an increase in power consumption can be suppressed even if the drive frequency is increased.

Hereinafter, an example of drive control suitable for an active matrix drive type organic EL display device will be described.
In addition, the well-known or well-known technique of the said technical field is applied to the part which is not illustrated or described in particular in this specification.
Moreover, the form example demonstrated below is one form example of invention, Comprising: It is not limited to these.

(A) Form example 1
(A-1) Overall Configuration of Organic EL Display Device FIG. 3 shows the main components of the organic EL display device 21. The organic EL display device 21 includes an organic EL panel 23, a data line driver 25, a scanning line driver 27, and a timing generator 29 as main components.

(A-2) Configuration of Each Part The organic EL panel 23 is a self-luminous display panel in which the pixels 31 are arranged in a matrix according to the panel resolution. In the case of this embodiment, the organic EL panel 23 is for color display, and the pixels 31 are arranged for each emission color. However, in the case where the pixel 31 is an organic EL element having a structure in which a plurality of light emitting layers are stacked, one pixel 31 corresponds to a plurality of light emitting colors.

FIG. 4 shows a connection relationship between the pixel 31 formed at the intersection of the data line DL and the scanning line WL and the driving circuit.
The pixel 31 includes a switch element T1, a capacitor C, a current drive element T2, and an organic EL element D.

  The switch element T1 is a transistor that controls writing of the signal voltage applied to the data line DL to the capacitor C. The write signal WS is supplied from the scanning line driver 27 to each switch element T1 through the scanning line WL.

  The capacitor C is a storage element that holds the written signal voltage Vin for one frame. By using the capacitor C, even when the signal voltage Vin is written line-sequentially, the same light emission mode as that in the case of writing by the frame sequential scanning method is realized.

  The current drive element T2 is a transistor that supplies a drive current corresponding to the signal voltage Vin held in the capacitor C to the organic EL element D. The drive current value here is determined by the voltage Vgs applied between the gate and source of the current drive element T2.

The data line driver 25 is a circuit device that drives the data line DL of the organic EL panel 23. The data line driver 25 uses a known circuit configuration.
The scanning line driver 27 is a circuit device that provides a write timing of the signal voltage Vin.

  The scanning line driver 27 in this embodiment controls the adjacent two scanning lines to a writable state every time the horizontal synchronization signal HS is input. A signal used for this write control is a write signal WS.

FIG. 5 shows an internal configuration example of the scanning line driver 27, and FIG. 6 shows an internal signal example.
The scanning line driver 27 includes a shift register 271, a latch 273, a buffer circuit 275, and an OR circuit 277. Except for the shift register 271, one is basically arranged on a horizontal scanning line (horizontal line).

The shift register 271 includes register stages having stages corresponding to the vertical resolution.
A write signal WS is input to the register stage at the head position at the head of each frame. The signal width T0 of the write signal WS is the same as the horizontal scanning period.

  The write signal WS is sequentially output to the next stage with a clock (FIG. 6A) synchronized with the horizontal synchronization signal HS (FIG. 6E), and is output to the latch 273 as the write signal WS corresponding to each scanning line DL. Is done. The latch 273 is for adjusting the timing of the one-line write signal ws.

  The buffer circuit 275 performs a process of shifting the signal level of the write signal ws to a signal level suitable for driving the organic El panel 23. FIG. 6B shows a one-line write signal ws (i) corresponding to the i-th scanning line. FIG. 6C shows a one-line write signal ws (i + 1) corresponding to the (i + 1) th scanning line.

  The logical sum circuit 277 generates a logical sum of the one-line write signal ws (i + 1) of the scan line DL to be driven and the one-line write signal ws (i) corresponding to the scan line DL one horizontal line before. FIG. 6D shows a two-line write signal WS (i + 1) output from the OR circuit 277 to the scanning line DL.

  The timing generator 29 is a processing device that generates various timing signals based on the data signal Din. A clock signal and other timing signals are supplied to the scanning line driver 27.

(A-3) Drive Operation FIG. 7 shows a drive signal example of the organic EL display device 1. This drive signal is a signal used for driving the pixels 31 (i-1, m) and 31 (i, m) at the positions shown in FIG. Here, the pixel 31 (i−1, m) is located at the intersection of the scanning line WL (i−1) located in the (i−1) th row and the data line DL (m) located in the mth column. The pixel located is shown.

A pixel 31 (i, m) indicates a pixel located at the intersection of the scanning line WL (i) located in the i-th row and the data line DL (m) located in the m-th column.
FIG. 7A shows an example of a signal waveform of the signal voltage Vin applied to the data line DL by the data line driver 25. The dullness in the rising waveform and falling waveform of the signal voltage Vin is recognized because the capacitance in the pixel and the wiring capacitance of the data line DL are affected.

  This dullness of the waveform generally increases as the drive frequency and capacity increase. Therefore, for the purpose of improving the frequency characteristics, the two-line write signal WS shown in FIGS. 7B and 7C is used in this embodiment. That is, the writing operation of the signal voltage Vin is started one horizontal scanning period before the original writing timing.

  FIG. 7B shows a two-line write signal WS (i−1) applied to the (i−1) th scanning line WL (i−1), and FIG. This is a two-line write signal WS (i) applied to the scanning line WL (i) in the row. FIG. 7D shows the horizontal synchronization signal HS.

  FIG. 9A shows a change in the writing potential (capacitor voltage Vc) of the capacitor C constituting the pixel 31 (i, m). The capacitor C constituting the pixel 31 (i, m) is written by a two-line writing signal WS (i) (FIG. 9B) from one horizontal scanning period before the original writing timing indicated by shading in the drawing. Be started. As a result, the same effect as the precharge can be obtained.

  That is, the precharge allows the data line driver 25 to write the signal voltage Vin of the pixel 31 (i, m) without improving the driving characteristics. This is because a similar signal voltage Vin is displayed on the front and rear horizontal lines in the moving image.

In particular, when the screen is switched from a black screen to a white screen as shown in FIG. 10, in the conventional writing method, the rising characteristic of the signal voltage Vin is greatly deteriorated as shown in FIG.
On the other hand, in the case of the two-line driving method described above, the pixel signal voltage Vin (i-1) on one horizontal line is already precharged before the original signal voltage Vin (i) is written to the capacitor C in the pixel. Has been.

  Therefore, the original writing of the signal voltage Vin (i) is completed in a short time as shown in FIG. This operation characteristic is the same as the operation characteristic when the pixel capacitance is small. Therefore, the rising characteristic of the signal voltage Vin (I, m) (FIG. 12B) corresponding to each pixel is greatly improved as compared with the conventional example (FIG. 12A). FIG. 12 shows a change in the signal voltage Vin between frames.

In the case of the driving method of this embodiment, power consumption can also be reduced. The power consumption W is calculated by C · V ² · f (C: capacitance, V: voltage, f: frequency). In this embodiment, the pixel capacitance appears to be apparently smaller by improving the frequency characteristics. It is because it can do.

(A-4) Effect of Embodiment As described above, even if the resolution and drive frequency of the organic EL panel 23 are increased by adopting the driving method described in this embodiment, the pixel capacity is almost ignored. Thus, the rising and falling characteristics of the signal voltage Vin can be improved. In addition, an increase in power consumption can be suppressed as much as possible.

That is, low power consumption can be realized without increasing the cost even if the drive frequency is increased to some extent.
In addition, when the pixel capacitance is no longer negligible with respect to the capacitance and resistance of the data line DL, it is possible to follow the increase in the drive frequency easily and at low cost without increasing the write voltage (overdrive). Can do.

(B) Other Mounting Examples (B-1) Other Pixel Structures In the above-described embodiments, the case where the switch element T1 is configured by an N-channel FET and the current drive element T2 is configured by a P-channel FET has been described.
However, this combination is not necessarily required depending on the manufacturing process.

  For example, both the switch element T1 and the current drive element T2 may be constituted by N-channel FETs. FIG. 13 shows an equivalent circuit of a pixel corresponding to this case. In this case, one electrode of the capacitor C is connected to the gate terminal of the current driver element T2, and the other electrode is connected to the drain terminal.

  Further, for example, the switch element T1 may be configured with a P-channel FET, and the current drive element T2 may be configured with an N-channel FET. Further, for example, both the switch element T1 and the current drive element T2 may be constituted by P-channel FETs.

(B-2) Method for Generating 2-Line Write Signal In the embodiment described above, the case where the scanning line driver 27 has the internal configuration shown in FIG. 5 has been described. That is, a logical sum circuit 277 that generates a logical sum of one line write signal of the scanning line DL corresponding to the output side of the buffer circuit 275 and one line write signal corresponding to the scanning line DL one horizontal line before is arranged. Explained.

However, the two-line write signal WS can be generated by other circuit configurations.
FIG. 14 shows another configuration example of the scanning line driver 27. In FIG. 14, the same reference numerals are given to the portions corresponding to FIG. 5.

The scanning line driver 27 illustrated in FIG. 14 includes a shift register 271, a latch 273, a delay unit 281, an SR flip-flop 283, and a buffer circuit 275.
The delay device 281 is a gate circuit that delays the write signal ws of the corresponding scanning line WL by one clock (one horizontal scanning period).

  The SR flip-flop 283 inputs the output of the latch 273 corresponding to the previous scanning line DL to the set end, and inputs the output of the delay unit 281 corresponding to the scanning line DL to be driven to the reset end. It is. The SR flip-flop 283 operates at the rising edge of the input signal.

  At this time, the SR flip-flop 283 maintains a two-line write signal WS (i + 1) that maintains the on-voltage from one horizontal scanning period before the writing timing of the scanning line DL to be driven to the end of the original writing period. Is output.

  The two-line write signal can also be realized by applying other circuit configurations. For example, a circuit configuration that does not use the delay device 281 is also possible. In this case, a one-line write signal ws for controlling writing of the next horizontal line may be input to the reset terminal of the SR flip-flop 283.

(B-3) Several Line Write Signal In the above-described embodiment, a case has been described in which writing to the corresponding pixel is started one horizontal line before the original write timing.
However, writing to the corresponding pixel may be started from two or more horizontal lines before.

(B-4) Product example (a) Drive IC
The organic EL panel 23, the data line driver 25, and the scanning line driver 27 constituting the organic EL display device 21 can all be formed on one panel, but the driver and the pixel matrix are separately manufactured and distributed. You can also

  For example, the data line driver 25 and the scanning line driver 27 can be manufactured as independent drive ICs (integrated circuits) and can be distributed independently of the organic EL panel 23.

(B) Display module The organic EL display device 21 in the embodiment described above can also be distributed in the form of a display module which is an intermediate product.

  FIG. 15 shows an appearance example of the display module 41. The display module 41 has a structure in which a facing portion 43 is bonded to the surface of the support substrate 45. The facing portion 43 uses a glass or other transparent member as a base material, and a color filter, a protective film, a light shielding film, and the like are disposed on the surface thereof.

  The display module 41 may be provided with an FPC (flexible printed circuit) 47 and the like for inputting and outputting signals and the like to the support substrate 45 from the outside.

(C) Electronic device The organic EL display device 21 in the embodiment described above is also distributed in a product form mounted on an electronic device.
FIG. 16 shows a conceptual configuration example of the electronic device 51. The electronic device 51 includes the organic EL display device 21 and the system control unit 53 described above. The processing content executed by the system control unit 53 differs depending on the product form of the electronic device 51.

Note that the electronic device 51 is not limited to a device in a specific field as long as it has a function of displaying an image or video generated in the device or input from the outside.
As this type of electronic equipment 51, for example, a television receiver is assumed. FIG. 17 shows an example of the appearance of the television receiver 61.

  On the front surface of the housing of the television receiver 61, a display screen 67 composed of a front panel 63, a filter glass 65, and the like is disposed. The portion of the display screen 67 corresponds to the organic EL display device 21 described in the embodiment.

  In addition, for example, a digital camera is assumed as this type of electronic device 51. FIG. 18 shows an appearance example of the digital camera 71. FIG. 18A shows an example of the appearance on the front side (subject side), and FIG. 18B shows an example of the appearance on the back side (photographer side).

  The digital camera 71 includes an imaging lens (FIG. 18 shows the state in which the protective cover 73 is closed, so that it is disposed on the back side of the protective cover 73), a flash light emitting unit 75, a display screen 77, a control switch 79 and a shutter. The button 81 is configured. Among these, the portion of the display screen 77 corresponds to the organic EL display device 21 described in the embodiment.

For example, a video camera is assumed as this type of electronic apparatus 51. FIG. 19 shows an appearance example of the video camera 91.
The video camera 91 includes an imaging lens 95 that images a subject in front of a main body 93, a shooting start / stop switch 97, and a display screen 99. Among these, the display screen 99 corresponds to the organic EL display device 21 described in the embodiment.

  In addition, as this type of electronic device 51, for example, a portable terminal device is assumed. FIG. 20 shows an example of the appearance of a mobile phone 101 as a mobile terminal device. A cellular phone 101 illustrated in FIG. 20 is a foldable type, and FIG. 20A illustrates an appearance example in a state where the housing is opened, and FIG. 20B illustrates an appearance example in a state where the housing is folded.

  The cellular phone 101 includes an upper housing 103, a lower housing 105, a connecting portion (in this example, a hinge portion) 107, a display screen 109, an auxiliary display screen 111, a picture light 113, and an imaging lens 115. Among these, the display screen 109 and the auxiliary display screen 111 correspond to the organic EL display device 21 described in the embodiment.

Further, for this type of electronic device 51, for example, a computer is assumed. FIG. 21 shows an example of the appearance of the notebook computer 121.
The notebook computer 121 includes a lower casing 123, an upper casing 125, a keyboard 127, and a display screen 129. Among these, the display screen 129 corresponds to the organic EL display device 21 described in the embodiment.

  In addition to these, the electronic device 51 may be an audio playback device, a game machine, an electronic book, an electronic dictionary, or the like.

(B-5) Other Display Device Examples In the description of the embodiments, the case where the display device is the organic EL display device 21 has been described.
However, the scanning line driver 27 described in the embodiment can be applied to other self-luminous display devices. For example, the present invention can be applied to an inorganic EL display device, a display device in which LEDs are arranged, an FED display device, a PDP display device, and the like.

(B-6) Control Device Configuration In the above description, the case where the drive timing of the scanning line driver 27 is controlled by hardware has been described.
However, the generation processing and output timing may be controlled through software processing.

(B-7) Others Various modifications can be considered for the above-described embodiments within the scope of the invention. Various modifications and applications created or combined based on the description of the present specification are also conceivable.

It is a figure which shows the example of a conventional drive. It is a figure which shows the prior art example of a display device. It is a figure which shows the structural example of a display device. It is a figure which shows the structural example of a pixel. It is a figure which shows the structural example of a scanning line driver. It is a figure which shows the example of a drive of a scanning line driver. It is a figure which shows the example of a drive of a display device. It is a figure explaining the pixel position corresponding to a drive signal. It is a figure explaining the change of the capacitor voltage at the time of writing. It is a figure which shows the example of a switching of a screen. It is a figure which shows the change of the capacitor voltage of a prior art example, and the change of the capacitor voltage of a form example. It is a figure explaining the write-in characteristic by a form example. It is a figure which shows the other structural example of a pixel. It is a figure which shows the other structural example of a scanning line driver. It is a figure which shows the structural example of a display module. It is a figure which shows the function structural example of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device.

Explanation of symbols

21 Organic EL Display Device 23 Organic EL Panel 25 Data Line Driver 27 Scan Line Driver 29 Timing Generator 51 Electronic Equipment 53 System Control Unit

Claims (11)

In a display device driving circuit for driving an active matrix driving type self-luminous display device,
A display device driving circuit, wherein a signal voltage writing signal is controlled to be in an on state from one horizontal scanning period before the writing timing of a signal voltage to be originally written to the end of the original writing period. In a display device driving circuit for driving an active matrix driving type self-luminous display device,
A display device driving circuit, wherein a signal voltage writing signal is controlled to be in an ON state from a few horizontal scanning periods before a writing timing of a signal voltage to be originally written to an expiration time of the original writing period. A self-luminous display region having an active matrix drive type pixel structure;
And a data line driving circuit for controlling a signal voltage write signal to be in an on state from one horizontal scanning period before the write timing of the signal voltage to be originally written to the end of the original write period. Matrix-driven self-luminous display device. A self-luminous display region having an active matrix drive type pixel structure;
A data line driving circuit for controlling a signal voltage write signal to be in an on state from several horizontal scanning periods before the write timing of the signal voltage to be originally written to the end of the original write period. Matrix-driven self-luminous display device. The self-luminous display device according to claim 3 or 4,
A self-luminous display device, wherein each pixel is composed of an electroluminescent element. A self-luminous display region having an active matrix drive type pixel structure;
A data line driving circuit for controlling a signal voltage writing signal to be in an ON state from one horizontal scanning period before the writing timing of the signal voltage to be originally written to the end of the original writing period;
An electronic device comprising: a system control unit. A self-luminous display region having an active matrix drive type pixel structure;
A data line driving circuit for controlling a signal voltage write signal to be in an on state from a few horizontal scanning periods before the write timing of the signal voltage to be originally written until the end of the original write period;
An electronic device comprising: a system control unit. In a display device driving method for driving an active matrix driving type self-luminous display device,
A display device driving method, wherein a signal voltage write signal is controlled to be in an on state from one horizontal scanning period before a signal voltage write timing to be originally written to an end point of the original write period. In a display device driving method for driving an active matrix driving type self-luminous display device,
A display device driving method, wherein a signal voltage write signal is controlled to be in an ON state from a few horizontal scanning periods before a write timing of a signal voltage to be originally written to an end point of the original write period. In a computer that controls the drive timing of an active matrix drive type self-luminous display device,
A computer program for executing a process for controlling a signal voltage write signal to be in an on state from one horizontal scanning period before the write timing of a signal voltage to be originally written to the end of the original write period. In a computer that controls the drive timing of an active matrix drive type self-luminous display device,
A computer program for executing a process for controlling a signal voltage write signal to be in an ON state from a time several scanning periods before the write timing of a signal voltage to be originally written to the end of the original write period.

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