JP2008165159A - Electro-optical device, driving method thereof, and electronic apparatus - Google Patents

Abstract

The present invention makes it possible to perform measurement after completion of an electro-optical device to improve the effectiveness of the measurement result.
A measurement signal F supplied from an input / output terminal T2 in a first mode is supplied to the gate of a driving transistor NH1 via a data line 14 (G), and the measurement signal F supplied from an input / output terminal T4. Is supplied to the source of the driving transistor NH1 through the data line 14 (B) adjacent to the data line 14 (G). On the other hand, the source voltage of the drive transistor NH1 is output as a signal under measurement via the potential line 17 (G).
[Selection] Figure 9

Description

  The present invention relates to an electro-optical device including an electro-optical element such as an OLED (Organic Light Emitting Diode) element, a method of driving this type of electro-optical device, and an electronic apparatus including the electro-optical device.

  The electro-optical device includes a plurality of pixels arranged on a substrate corresponding to each intersection of a plurality of scanning lines and a plurality of data lines, and the pixel level is determined according to a data signal supplied to each data line. Key is controlled. Various circuits are conceivable for the pixel, but one having an OLED element as an electro-optical element and a transistor for supplying a driving current to the OLED element is known. In such a pixel, the luminance of each pixel becomes non-uniform due to variations in transistor characteristics (for example, threshold voltage) and OLED element characteristics.

In order to solve this problem, Patent Document 1 discloses in advance the measurement of the electrical characteristics of the transistors constituting the pixel, and the correction data according to the measurement results and the deterioration prediction data for predicting the deterioration of the OLED element before shipping the product. A technique of storing and correcting using correction data and deterioration prediction data is disclosed.
JP 2004-145257 A (paragraph number 0024)

  However, in the technique disclosed in Patent Document 1, since correction data is stored before the product is shipped, it can be corrected even if the electrical characteristics of the transistor change after the product has passed to the end user. could not. In addition, since the deterioration of the OLED element is only a prediction, accurate correction is difficult. The present invention has been made in view of such circumstances, and an object of the present invention is to improve the effectiveness of measurement results by enabling measurement after completion of the electro-optical device.

  In order to solve the above problems, an electro-optical device according to the present invention is an electro-optical device in which a plurality of pixels each including an electro-optical element are connected to each data line, and the gradation of each electro-optical element A signal generator (for example, the data line driving circuit 24 of the embodiment) that drives each electro-optic element by outputting a data signal corresponding to the gradation data that designates the gradation, and a gradation that exceeds a threshold value is designated by the gradation data A measurement object selection unit for selecting the electro-optical element, and a measurement process for driving the electro-optical element by outputting a measurement signal and acquiring a signal under measurement indicating characteristics of the electro-optical element when driven by the measurement signal And a measuring unit that executes the electro-optic element selected by the measurement target selecting unit among the plurality of electro-optic elements.

  In the above configuration, the measurement process for measuring the characteristics of the electro-optic element based on the gradation data used for driving the electro-optic element by the signal generation unit is executed. That is, it is possible to measure the characteristics of the electro-optical element as needed when the electro-optical device is used after completion (after shipment). In addition, since the measurement process is selectively performed on the electro-optic element in which the gradation exceeding the threshold is specified by the gradation data, for example, when the gradation of the electro-optic element fluctuates (for example, emits light) during the measurement process. Even in this case, it is possible to reduce the difference between the gradation of the electro-optical element during driving by the signal generation unit and the gradation of the electro-optical element during measurement processing.

  In a preferred aspect of the present invention, the apparatus includes a storage unit (for example, a measurement history memory 58) that stores measurement history data indicating whether or not the measurement process has been performed on each electro-optic element, When the number of electro-optic elements whose gradation specified by the data exceeds the threshold exceeds a predetermined number, the measurement processing is performed for the electro-optic elements that have not yet been measured based on the measurement history data stored in the storage unit. Execute. According to the above aspect, since the measurement process is preferentially executed for the electro-optical elements that have not yet been subjected to the measurement process, the measurement process is performed by limiting the number of electro-optical elements to be subjected to one measurement process. Thus, it is possible to efficiently execute the measurement process for many electro-optic elements while shortening the time required.

  In a further preferred aspect, when the first gradation exceeding the threshold is specified by gradation data, the measurement unit is configured when the second gradation exceeding the first gradation is specified by gradation data. The measurement signal is generated so that the electro-optic element during the measurement process has a low gradation. According to the above aspect, in the electro-optical element to be measured, the difference between the gray level of the electro-optical element when driven by the signal generation unit and the gray level of the electro-optical element during the measurement process is further reduced. .

  In a further preferred aspect, the signal generation unit is configured such that the gray level when the electro-optic element selected by the measurement target selection unit is driven by supplying a data signal is lower than that when the data signal is not selected. Correct the data signal. For example, the data depending on the presence or absence of the measurement process so that the light emission amount of the electro-optical element when driven by the signal generation unit becomes the light emission amount obtained by reducing the light emission amount in the measurement process from the light emission amount according to the gradation data. A signal is generated. According to the above aspect, since the gradation of the electro-optical element selected as the object of the measurement process and the gradation of the non-selected electro-optical element are made uniform, the advantage that the influence of the measurement process is further reduced. There is. Note that the influence of the gradation of the electro-optic element during the measurement process becomes more prominent as the gradation of the electro-optic element when driven by the signal generator is lower. Therefore, the data signal may be corrected so that the gradation at the time of driving by the signal generation unit is reduced only when the gradation specified by the gradation data is low.

An electro-optical device according to a preferred aspect of the present invention includes a threshold setting unit that variably controls the threshold. According to this aspect, the number of electro-optic elements selected by the measurement target selection unit can be adjusted according to the threshold set by the threshold setting unit. Therefore, by controlling the threshold according to the situation in which the electro-optical device is used, measurement is performed while maintaining a state where the difference in gradation of the electro-optical element between driving and measurement processing is not easily perceived by the observer. The number of electro-optic elements to be processed can be efficiently ensured.
In a more specific aspect, a lightness specifying unit that specifies the lightness of an image output from the plurality of pixels is provided, and the threshold setting unit controls the threshold according to the lightness specified by the lightness specifying unit. . For example, the threshold setting unit lowers the threshold as the lightness specified by the lightness specifying unit is higher (that is, increases the number of electro-optical elements to be measured). In another aspect, an illuminance measuring unit that measures the environmental illuminance of the electro-optical device is provided, and the threshold setting unit controls the threshold according to the environmental illuminance measured by the illuminance measuring unit. For example, the threshold value setting unit decreases the threshold value as the environmental illuminance measured by the illuminance measurement unit increases (that is, increases the number of electro-optic elements to be measured).

An electro-optical device according to a preferred aspect of the present invention (hereinafter sometimes referred to as “wiring-type electro-optical device”) includes a plurality of pixels each including the electro-optical element connected to each of a plurality of data lines. And a plurality of input / output terminals provided corresponding to each of the plurality of data lines, and a data signal generated by the signal generation unit in the drive mode via the input / output terminals. In the measurement mode, the electro-optic element is connected to the data line corresponding to the pixel selected by the measurement target selection unit and the input / output terminal corresponding to the data line adjacent to the data line. An input / output unit (for example, the transistor of the embodiment) that inputs and outputs the measurement signal and the signal under measurement for measuring the characteristics of the constituent elements of the pixel (for example, the drive transistor NH1 of the embodiment). And the pixel captures a data signal supplied via the data line in the drive mode, and passes the data line and a data line adjacent to the data line in the measurement mode. And a selection unit (for example, the transistors N2 to N4, NT1, and NT2 in the embodiment) that takes in the measurement signal and outputs the signal to be measured.
According to the electro-optical device according to the above aspect, the measurement signal and the signal under measurement are transmitted using the data line of the adjacent pixel in addition to the data line corresponding to the pixel to be measured. That is, since the adjacent data lines are also used for measurement, it is not necessary to provide special wiring for measurement, or the number of measurement wirings can be reduced. Further, since the measurement signal and the signal under measurement are input / output via the input / output terminal for inputting the data signal in the drive mode, it is not necessary to newly provide an input / output terminal.

  In the wiring-type electro-optical device exemplified above, a plurality of potential lines paired with each of the plurality of data lines, a reference potential line to which a reference potential is supplied, and the plurality of data in the driving mode. And connecting the reference potential line and the plurality of potential lines, and in the measurement mode, the plurality of data lines, the plurality of potential lines, and the plurality of input lines. A signal switching unit that selectively connects to an output terminal, and the input / output unit includes a data line and a potential line corresponding to a pixel to be measured in the measurement mode, and the data by the signal switching unit. Preferably, the measurement signal and the signal under measurement are input / output via the data line adjacent to the line and the input / output terminal connected to the potential line adjacent to the potential line. According to the present invention, a measurement signal and a signal under measurement can be transmitted using a pair of a data line and a potential line and a pair of a data line and a potential line adjacent thereto, so that the number of signals to be transmitted is increased. Therefore, it becomes possible to obtain the characteristics of the constituent elements in detail.

  More specifically, in the measurement mode, the characteristics of the constituent elements are measured every N (N is a natural number of 2 or more) pixels, the measurement target pixels are shifted, and the measurement is repeated N times. The entry output unit preferably changes the input / output terminal for inputting / outputting the measurement signal and the signal under measurement in accordance with the change of the pixel to be measured. Since the number of input / output terminals is limited, it is possible to increase the number of input / output terminals for measurement when the number of measurement signals and signals under measurement is large. According to the present invention, the number of input / output terminals is divided into N times. Since the characteristics are measured, the characteristics of the constituent elements can be measured without adding input / output terminals. Of course, the characteristics of a plurality of pixels may be measured by one measurement out of N measurements. For example, when a pixel corresponds to a plurality of display colors, the measurement may be performed for each display color. In this case, measurement is simultaneously performed for pixels having the same display color. Therefore, the measurement time can be shortened as compared with the case where measurement is performed for each pixel.

  Here, the pixel includes a transistor that outputs a driving current according to the data signal, and an electro-optical element that emits light with a luminance according to the driving current, and a component to be measured is the transistor. Preferably, the measurement signal gives a gate potential of the transistor, and the signal under measurement is at least one of a source potential and a drain potential of the transistor. In this case, the electrical characteristics of the driving transistor can be measured.

  The pixel includes a transistor that outputs a driving current according to the data signal, and an electro-optical element that emits light with a luminance according to the driving current, and a component to be measured is the electro-optical element. The measurement signal may be a voltage applied to the electro-optic element, and the signal under measurement may be a current flowing through the electro-optic element. In this case, the characteristics of the electro-optical element can be measured.

  In the wiring-type electro-optical device, a storage unit that stores correction data generated so that the luminance between the pixels approaches uniform based on the signal under measurement obtained in the measurement mode, and reads out from the storage unit A correction unit that corrects gradation data indicating the gradation of the pixel using the correction data to generate corrected gradation data, and the signal generation unit is configured based on the corrected gradation data. Preferably, the data signal is generated. According to the present invention, since the gradation data is corrected based on the correction data generated based on the measurement result, it is possible to reduce the luminance variation between the pixels.

  Here, the correction data indicates a first coefficient corresponding to a threshold voltage of the transistor and a second coefficient corresponding to a current amplification factor of the transistor, and the correction unit includes the first coefficient. Preferably, the gradation data is added to the gradation data, and the gradation data is multiplied based on the second coefficient to generate the corrected gradation data. According to the present invention, correction is performed by addition and multiplication. Of course, the addition process includes not only the case of adding a positive value but also the case of adding a negative value. In this sense, the addition process substantially functions as a subtraction process.

  The wiring-use electro-optical device designates the drive mode and the measurement mode, assigns the drive mode to a part of a vertical scanning period, and assigns the measurement mode to the remaining period of the vertical scanning period. It is preferable to provide a control unit to be assigned to. According to the present invention, since the state of the constituent elements of the pixel is measured and corrected during the period in which the image is displayed, the image can be displayed with accurate luminance. Although the pixel temperature differs immediately after the power is turned on and after a lapse of a certain time, according to the present invention, correction can be performed following a short-term temperature change, and further, long-term It is also possible to perform a correction following the change.

  Next, an electronic apparatus according to the present invention includes the above-described electro-optical device, and includes, for example, a display device such as a light emitting device and a liquid crystal device, a personal computer, a mobile phone, a digital still camera, and a video camera. To do. In addition, for example, it can be used as a line head in an optical writing type image forming apparatus (for example, a printer).

  Next, a driving method of an electro-optical device according to the present invention is a driving method of an electro-optical device including a plurality of electro-optical elements, according to gradation data that specifies the gradation of each electro-optical element. Each electro-optical element is driven by the output of the data signal, while the electro-optical element whose gradation exceeding the threshold is specified by the gradation data is selected, and the electro-optical element is driven by the output of the measurement signal and the measurement A measurement process for obtaining a signal under measurement indicating characteristics of the electro-optical element when driven by a signal is performed on the selected electro-optical element among the plurality of electro-optical elements. Also by the above method, the same operation and effect as the electro-optical device according to the invention can be obtained.

  In addition, a plurality of pixels each including the electro-optical element is connected to each data line, and an electro-optical device (wiring-combined type electro-optical device) having a plurality of input / output terminals provided corresponding to each data line. In the driving mode, a data signal is supplied to the data line via the input / output terminal in the driving mode, and the data line corresponding to the selected pixel and the data line are adjacent to each other in the measurement mode. The measurement signal and the signal under measurement are input / output via the input / output terminal corresponding to the data line, and in the driving mode, the data signal supplied via the data line is taken into the pixel, and the measurement is performed. In the mode, the measurement signal is taken into the pixel through the data line and the data line adjacent to the data line, and the measured signal is output. And butterflies.

  In the method of driving a wiring combined type electro-optical device, the electro-optical device includes a plurality of potential lines paired with each of the plurality of data lines and a reference potential line to which a reference potential is supplied, and the driving In the mode, the plurality of data lines and the plurality of input / output terminals are connected, and the reference potential line and the plurality of potential lines are connected. In the measurement mode, the plurality of data lines and the plurality of data lines are connected. A data line and a potential line corresponding to a pixel to be measured, a data line adjacent to the data line, and a potential line adjacent to the potential line are selectively connected to the potential line and the plurality of input / output terminals. Preferably, the measurement signal and the signal under measurement are input / output via the input / output terminal connected to the terminal. According to the present invention, a measurement signal and a signal under measurement can be transmitted using a pair of a data line and a potential line and a pair of a data line and a potential line adjacent thereto, so that the number of signals to be transmitted is increased. Therefore, it becomes possible to obtain the characteristics of the constituent elements in detail.

  Here, the correction data generated so that the luminance between the pixels approaches uniformly based on the signal under measurement obtained in the measurement mode is stored, and the gradation of the pixel is adjusted using the stored correction data. It is preferable that corrected gradation data is generated to generate corrected gradation data, and the data signal is generated based on the corrected gradation data. According to the present invention, since the characteristics of the constituent elements are measured and correction is performed based on the measurement results, the difference in luminance between pixels can be reduced.

  In the above-described invention, the electro-optical element is an element whose optical characteristics change depending on electric energy, and includes, for example, a liquid crystal element in addition to a light-emitting element such as an organic light-emitting diode or an inorganic light-emitting diode.

<A: First Embodiment>
FIG. 1 is a block diagram showing a configuration of an electro-optical device 1 according to the first embodiment of the present invention. The electro-optical device 1 operates in a drive mode for displaying an image and a measurement mode for measuring electrical characteristics of the drive transistor NH1 and the OLED element 11 (see FIG. 2) that are components of the pixel circuit P. As shown in FIG. 1, the electro-optical device 1 includes an electro-optical panel 10, a scanning line driving circuit 22, a data line driving circuit 24, a voltage generation circuit 27, a control circuit 29, a correction circuit 30, a memory 40, and measurement control. A circuit 50 is provided.

  In the pixel region A of the electro-optical panel 10, m (m is a natural number) scanning lines 12 extending in the X direction (row direction) are formed. Although omitted in FIG. 1, five control lines are formed in parallel with the scanning lines 12. In the pixel region A, n data lines 14 extending in the Y direction (column direction) orthogonal to the X direction and potential lines 17 paired with the data lines 14 are formed (n is a natural number). . A pixel circuit P is arranged corresponding to each intersection of the scanning line 12 and the data line 14. Therefore, these pixel circuits P are arranged in a matrix in the X direction and the Y direction in the pixel region A. Each pixel circuit P includes an OLED element 11 that is a current-driven self-luminous element. Note that “R”, “G”, and “B” shown in the drawing represent display colors of the pixel circuits P. In this case, the emission color of the OLED element 11 may correspond to “R”, “G”, and “B”, or the emission color of the OLED element 11 may be white and the display color may be obtained by a color filter.

  Further, n input / output terminals T <b> 1 to Tn corresponding to the n data lines 14 are provided at the end of the electro-optical panel 10. Further, a switching circuit 25 is formed between the plurality of input / output terminals T1 to Tn, the plurality of data lines 14, and the plurality of potential lines 17. The switching circuit 25 includes reference potential lines Lr, Lb, and Lg that supply an R reference potential REF-R, a G reference potential REF-G, and a B reference potential REF-B. The switching circuit 25 connects the plurality of data lines 14 and the plurality of input / output terminals T1 to Tn in the driving mode, and connects the reference potential lines Lr, Lb, Lg and the plurality of potential lines 17 in the measurement mode. The plurality of data lines 14 and the plurality of potential lines 17 are selectively connected to the plurality of input / output terminals T1 to Tn.

  The scanning line driving circuit 22 and the data line driving circuit 24 are IC chips, and are mounted outside the electro-optical panel 10 (for example, on a wiring board mounted on the electro-optical panel 10). Note that at least one of the scanning line driving circuit 22 and the data line driving circuit 24 may be mounted on the electro-optical panel 10 by COG (Chip On Glass) technology. The scanning line driving circuit 22 sequentially selects each of the m scanning lines 12 in the driving mode. More specifically, the scanning line driving circuit 22 sends scanning signals EW-1, EW-2,..., EW-m that sequentially become active levels (H levels) to the scanning lines 12 for each horizontal scanning period. Output. When the scanning signal EW-i (i is an integer satisfying 1 ≦ i ≦ m) becomes an active level, it means that the i-th row has been selected. In the measurement mode, the scanning line driving circuit 22 selects one scanning line 12 designated by the control circuit 29 and supplies the scanning signal EW-i having an active level.

  On the other hand, the data line driving circuit 24 supplies the data signal D to each pixel circuit P connected to the scanning line 12 selected by the scanning line driving circuit 22 in the driving mode. The data signal Dj (j is an integer satisfying 1 ≦ j ≦ n) is a voltage signal that specifies the luminance (gradation) of the pixel circuit P in the j-th column. In addition, the data line driving circuit 24 supplies the measurement signal F to the pixel circuit P in the measurement mode and obtains the signal under measurement M indicating the measurement result from the pixel circuit P. Note that the scanning line driving circuit 22 and the data line driving circuit 24 can be formed not only by an IC chip but also partially or entirely in a glass substrate.

  The voltage generation circuit 27 generates the following voltages used in the electro-optical device 1. First, the power supply voltages VE-R, VE-G, and VE-B are voltages supplied to the R, G, and B color pixel circuits P, respectively, and are control signals supplied from the control circuit 29. To control whether or not to output. Although it is always output in the drive mode, in the measurement mode, the pixel circuit P to be measured is controlled for each color as described later, and only the corresponding power supply voltage is output. Next, the voltage generation circuit 27 outputs the R reference potential REF-R, the G reference potential REF-G, and the B reference potential REF-B. The R reference potential REF-R, the G reference potential REF-G, and the B reference potential REF-B are voltages that define the source potential of the driving transistor.

  The control circuit 29 supplies control signals to the scanning line drive circuit 22, the data line drive circuit 24, the switching circuit 25, the voltage generation circuit 27, and the measurement control circuit 50 to control these circuits. In addition, the control circuit 29 executes switching between the drive mode and the measurement mode. In the present embodiment, the measurement mode is assigned to part or all of the vertical blanking period. In this way, by executing the measurement mode when driving the pixel circuit P in the drive mode, it becomes possible to perform corrections following the state of the drive transistor and OLED element that change from moment to moment, thereby improving display quality. Can do.

The gradation data d specifying the gradation of each pixel circuit P is supplied to the measurement control circuit 50 and the correction circuit 30.
In the measurement mode, the measurement control circuit 50 executes a process for measuring the characteristics of the components of the pixel circuit P (hereinafter referred to as “measurement process”). The measurement process includes a process of outputting the measurement signal F from the data line driving circuit 24 and a process of acquiring the signal under measurement M from the data line driving circuit 24. The signal under measurement M acquired by the measurement control circuit 50 is output to the correction circuit 30. The correction circuit 30 generates correction data Dh based on the signal under measurement M, and stores the generated correction data Dh in the memory 40. On the other hand, in the drive mode, the correction circuit 30 reads the correction data Dh from the memory 40 and supplies the corrected gradation data dh obtained by correcting the gradation data d based on the correction data Dh to the data line driving circuit 24. To do. For example, the correction data Dh includes first data H1 corresponding to the threshold voltage of the driving transistor and second data H2 corresponding to the current amplification factor of the driving transistor. The correction circuit 30 is composed of a linear driver, and generates corrected gradation data dh by executing a linear operation according to the following equation.
Dh = (H1, H2)
dh = H1 + H2 * Dh

  The first data H1 and the second data H2 are obtained by measuring the current-voltage characteristics of the driving transistor, and are set so that the luminance between the pixels approaches uniform. The memory 40 in this example is volatile, but may be non-volatile. In addition, measurement of drive current and emission luminance is performed at the time of product shipment or immediately after power-on, and correction data obtained there and correction data obtained in real time are combined to correct gradation data d. Also good. The correction circuit 30 and the measurement control circuit 50 may be arranged as separate IC chips, or may be mounted on one IC chip.

  Next, the configuration of the pixel circuit P will be described with reference to FIG. In the drawing, only the pixel circuit P corresponding to the R color belonging to the i-th row is shown, but the other pixel circuits P have the same configuration. The pixel circuit P in the present embodiment is a voltage driving type (so-called voltage programming method) circuit in which the luminance (gradation) of the OLED element 11 is controlled in accordance with the voltage value of the data signal D. A so-called current programming method may be employed.

  As shown in FIG. 2, the pixel circuit P includes an OLED element 11, a capacitive element CH1, a p-channel transistor P1, n-channel transistors N1 to N4, NT1 and NT2, and a driving transistor NH1. The drive current that flows into the OLED element 11 is determined by the gate-source voltage of the drive transistor NH1. A capacitive element CH1 is provided between the gate and source of the driving transistor NH1. The capacitive element CH1 is a means for holding the voltage written during the writing period in the drive mode. Further, the control signal XEP-i is transmitted through the first control line L1, the control signal ETB-i is transmitted through the second control line L2, and the control signal ETG-i is transmitted through the third control line L3. The control signal ETR-i is supplied from the scanning line driving circuit 22 through the line L4, and the control signal EN-i is supplied through the fifth control line L5.

  A power supply voltage VEL-R is supplied to the source of the transistor P1, a control signal XEP-i is supplied to its gate, and its drain is connected to the drain of the driving transistor NH1. When the control signal XEP-i becomes low level (active), the transistor P1 is turned on, and the power supply voltage VEL-R is supplied to the drive transistor NH1.

  A transistor N2 is provided between the gate of the driving transistor NH1 and the data line. A scanning signal EW-i is supplied to the gate of the transistor N2 through the scanning line 12. When the scanning signal EW-i becomes high level, the data signal Dj supplied via the data line 14 is applied to one terminal of the capacitive element CH1. Transistors N3 and N4 are provided between the source of the driving transistor NH1 and the potential line 17. A power supply voltage VEL-R is supplied to the gate of the transistor N4. Since the power supply voltage VEL-R is always high in the drive mode, the transistor N4 is always on in the drive mode. On the other hand, the scanning signal EW-i is supplied to the gate of the transistor N3. Accordingly, when the i-th scanning line 12 is selected, the transistor N3 is turned on, and the R reference potential REF-R is supplied to the other terminal of the capacitive element CH1. After that, even when the scanning signal EW-i changes to the low level, a voltage corresponding to the gradation to be displayed is held between the terminals of the capacitive element CH1.

  A transistor N1 is provided between the source of the driving transistor NH1 and the anode of the OLED element 11, and a control signal EN-i is supplied to the gate thereof. The control signal EN-i is at a high level during the light emission period in the drive mode, and the drive current is supplied to the OLED element 11 during the period.

  A transistor NT1 is provided between the source of the driving transistor NH1 and the data line 14 of the pixel circuit P adjacent to the pixel circuit P, and the pixel circuit adjacent to the anode of the OLED element 11 and the pixel circuit P. Between the P potential line 17, a transistor NT2 is provided. The gates of the transistors NT1 and NT2 are connected to the fourth control line L4. In the G pixel circuit P, the gates are connected to the third control line L3, and in the B pixel circuit P, the gates are connected to the second control line L2.

  FIG. 3 is a timing chart for explaining the operation of the pixel circuit P in the drive mode. 4 shows the state of the pixel circuit P in the writing period, and FIG. 5 shows the state of the pixel circuit P in the light emission period. As shown in FIG. 3, the scanning signals EW-1, EW-2,... Sequentially become high level every horizontal scanning period 1H. A period during which each scanning signal EW is at a high level is a writing period Twrt. As shown in FIG. 4, in the writing period Twrt, the control signal XEP-1 is at a high level, so that the transistor P1 is in an off state, and the scanning signal EW-1 is at a high level, so that the transistors N2 and N3 are in an on state. Since the signal EN-1 is at a low level, the transistor N1 is in an off state, and the control signal ETR-1 is at a low level, so that the transistors NT1 and NT2 are in an off state. As a result, the data signal D1 is supplied to the gate of the drive transistor NH1, while the R reference potential REF-R is supplied to the source of the drive transistor NH1, and the potential difference is held by the capacitive element CH1.

  Further, as shown in FIG. 5, in the light emission period Tel, the control signal XEP-1 is at a low level, so that the transistor P1 is on, and the scanning signal EW-1 is at a low level, so that the transistors N2 and N3 are in an off state. Since the control signal EN-1 is at a high level, the transistor N1 is on, and the control signal ETR-1 is at a low level, so that the transistors NT1 and NT2 are off. As a result, the gate and source of the driving transistor NH1 are separated from the data line 14 and the potential line 17. At this time, the power supply voltage VEL-R is applied to the drain of the drive transistor NH1 via the transistor P1, and the drive current Iel flows into the OLED element 11 via the transistor N1. The magnitude of the drive current Iel is determined according to the gate-source voltage of the drive transistor NH1, the data signal D1 is generated based on the corrected gradation data dh, and the R reference potential REF-R is fixed. . Therefore, the drive current Iel is in accordance with the gradation to be displayed. As a result, the OLED element 11 can emit light with a desired luminance.

  Next, a specific configuration of the measurement control circuit 50 will be described with reference to FIG. As shown in the figure, the measurement control circuit 50 includes a gradation detection unit 52, a measurement object selection unit 54, a measurement unit 56, and a measurement history memory 58. Each part of the measurement control circuit 50 shown in FIG. 6 may be mounted on one IC chip, or each may be mounted on a separate IC chip.

  The gradation detector 52 is means for detecting a gradation value GR for each pixel circuit P from gradation data d sequentially supplied from the outside. The measurement target selection unit 54 performs measurement processing from a plurality (m × n) of pixel circuits P belonging to the pixel region A based on the gradation value GR of each pixel circuit P detected by the gradation detection unit 52. A predetermined number of target pixel circuits P are selected. The measurement target selection unit 54 of the present embodiment selects the pixel circuit P whose gradation value GR exceeds the threshold value TH as a measurement process target. Since the light emission amount of the electro-optical element 11 increases as the gradation value GR (the numerical value of the gradation data d) increases, the measurement target selection unit 54 performs electro-optics in which the light emission amount during driving in the drive mode exceeds a predetermined threshold value. It is grasped also as means for selecting the element 11.

  The measurement unit 56 selectively performs measurement processing (output of the measurement signal F and acquisition of the signal under measurement M) on the pixel circuit P selected by the measurement target selection unit 54 among the plurality of pixel circuits P belonging to the pixel region A. Is a means for executing. First, the measurement unit 56 designates each pixel circuit P to be subjected to measurement processing to the control circuit 29 and outputs the measurement signal F to the data line driving circuit 24, so that the gradation value GR becomes the threshold value. The pixel circuit P exceeding TH is selectively driven, and secondly, the signal under measurement M indicating the characteristics of the components of the pixel circuit P at the time of driving using the measurement signal F is passed through the data line driving circuit 24. Obtained and output to the correction circuit 30. In other words, the measurement unit 56 is means for prohibiting (stopping) measurement processing for the pixel circuits P that are not selected by the measurement target selection unit 54.

  The measurement history memory 58 stores measurement history data DL for each pixel circuit P. The measurement history data DL corresponding to one pixel circuit P is data (for example, a 1-bit flag) indicating whether or not a measurement process has been executed for the pixel circuit P in the past. Various storage circuits such as RAM (Random Access Memory) and EEPROM (Electrically Erasable Programmable Read Only Memory) are suitably employed as the measurement history memory 58.

  When the measurement process is completed within one vertical blanking period, the measurement unit 56 indicates that the measurement history data DL of the pixel circuit P that is the object of the current measurement process has been executed. Set to the numerical value “1”. It should be noted that immediately after the electro-optical device 1 is turned on or when the numerical value “1” is set in the measurement history data DL of all the pixel circuits P (that is, when the measurement processing is completed for all the pixel circuits P). ), All the measurement history data DL are initialized to a numerical value “0” indicating that the measurement processing is not completed. Alternatively, all the measurement history data DL may be initialized to a numerical value “0” when a predetermined time has elapsed since the last measurement process was performed on any pixel circuit P.

  By the way, if the number of pixel circuits P to be measured is too large, the measurement process may not be completed for all the pixel circuits P within one vertical blanking period. Further, if a sufficient time for executing the measurement process for a large number of pixel circuits P is secured for the measurement mode, the time that can be actually used for driving each pixel circuit P in the drive mode is limited. There is. Therefore, in the present embodiment, the number of pixel circuits P that can be subjected to measurement processing is limited to a predetermined number. That is, when the number of pixel circuits P selected by the measurement target selection unit 54 exceeds a predetermined value, the measurement unit 56 still performs measurement processing based on the measurement history data DL stored in the measurement history memory 58. The measurement process is preferentially executed for the pixel circuits P that are not. According to the above configuration, since redundant execution of measurement processing for one pixel circuit P is avoided, the number of pixel circuits P to be subjected to measurement processing within one vertical blanking period is limited. In view of a plurality of vertical blanking periods, it is possible to efficiently perform measurement processing for a large number of pixel circuits P.

  Next, the details of the switching circuit 25 and the configuration of its peripheral circuits will be described with reference to FIG. The switching circuit 25 includes a switch group SWR for R color, a switch group SWG for G color, and a switch group SWB for B color. Each switch group includes five switches Sr1 to Sr5, Sg1 to Sg5, and Sb1 to Sb5. These switches are turned on when the control signal supplied to the control terminal is at a high level, and turned off when the control signal is at a low level. The switching circuit 25 also includes a reference potential line Lr to which the R reference potential REF-R is supplied, a reference potential line Lg to which the G reference potential REF-G is supplied, and a reference potential to which the B reference potential REF-B is supplied. The reference potential lines Lr, Lg, and Lb are connected to the switches Sr3, Sg3, and Sb3, respectively.

  In the drive mode described above, the control signals VG-R, VG-G, and VG-B, and VRE-R, VRE-G, and VRE-B are at a high level, and the other control signals are at a low level. Therefore, the switches Sr1, Sg1, and Sb1, and Sr3, Sg3, and Sb3 are turned on, and the other switches are turned off. That is, in the drive mode, the switching circuit 25 connects the plurality of data lines 14 and the plurality of input / output terminals T1 to Tn, and connects the reference potential lines Lr, Lg, and Lb and the plurality of potential lines 17, respectively. Functions as a means to

  FIG. 8 shows a truth table of various control signals in the measurement mode. The measurement modes within one vertical blanking period include a first mode for measuring the characteristics of the drive transistor NH1 and a second mode for measuring the characteristics of the OLED element 11. That is, the measurement process executed within one vertical blanking period includes measurement of characteristics of the drive transistor NH1 in each pixel circuit P selected by the measurement target selection unit 54 and measurement of characteristics of the OLED element 11 in the pixel circuit P. Including.

  FIG. 9 shows the operation in the first mode when the G-color pixel circuit P is selected as the object of the measurement process. Since the control signal XEP-i is at the low level, the control signal ETG-i is at the high level, and the scanning signal EW-i is at the high level as shown by the thick frame in FIG. 8, the transistors P1, N2, N3 is turned on, and the transistor N1 is turned off. Further, since the power supply voltage VEL-G is turned on (high level) and VEL-R and VEL-B are turned off (low level), the transistor N4 of the G color pixel circuit P is turned on, while the R color and The transistor N4 of the B-color pixel circuit P is turned off. In addition, since the control signal ETG-i becomes high level, the transistors NT1 and NT2 of the G-color pixel circuit P are turned on. On the other hand, since the control signals ETR-i and ETB-i are at a low level, the transistors NT1 and NT2 of the R and B pixel circuits P are turned off.

Next, the control signals VG-G, VM-G, and VFIM-G supplied to the switching circuit 25 are at a high level, and the other control signals are at a low level. Accordingly, as shown in FIG. 9, the switches Sg1 and Sg4 of the switch group SWG are turned on, and the switch Sb5 of the switch group SWB is turned on.
At this time, the gate voltage VGIN is applied as the measurement signal F through the path of the input / output terminal T 2 → switch Sg 1 → data line 14 (G) corresponding to the G color pixel circuit → transistor N 2 → gate transistor NH 1. . The source voltage VSIN is applied as the measurement signal F through the source path of the input / output terminal T4 → the switch Sb5 → the data line 14 (B) corresponding to the B color pixel circuit → the transistor NT1 → the drive transistor NH1. Further, the source voltage VS of the driving transistor NH1 is the signal under measurement M, and the source of the driving transistor NH1 → the transistor N4 → the transistor N3 → the potential line 17 (G) corresponding to the G color pixel circuit → the switch Sg4 → the input / output terminal T3. It is taken out by the route.

  FIG. 11A shows a simplified circuit for measuring characteristics of the driving transistor NH1. As shown in this figure, the measurement signal F (VGIN, VSIN) is supplied through the input / output terminals T2 and T4, and the signal under measurement M (VS) is output through the input / output terminal T3. In addition, an ammeter is provided in the path of the input / output terminal T4, and current is measured. Thereby, the voltage-current characteristic of the driving transistor NH1 is measured.

  In the drive mode, a G-color data signal is output from the input / output terminal T2 shown in FIG. 9 toward the data line 14 (G), and a G reference potential REF-G is output toward the potential line 17 (G). did. On the other hand, in the first mode, when measuring the characteristics of the drive transistor NH1 of the G pixel circuit P, in addition to the data line 14 (G) and the potential line 17 (G), the data line 14 (G) The measurement signal F and the signal under measurement M are input / output using the adjacent data line 14 (B). As described above, the number of wirings can be reduced by combining the measurement wiring and the driving wiring.

  FIG. 10 shows an operation in the second mode when the G pixel circuit P is selected as a measurement processing target. Since the control signal EN-i is at a high level as shown by a thick frame in FIG. 8, the transistor N1 is turned on and the transistors P1, N2, and N3 are turned off as shown in FIG. Further, since the power supply voltage VEL-G is turned on (high level) and VEL-R and VEL-B are turned off (low level), the transistor N4 of the G color pixel circuit P is turned on, while the R color and The transistor N4 of the B-color pixel circuit P is turned off. In addition, since the control signal ETG-i becomes high level, the transistors NT1 and NT2 of the G-color pixel circuit P are turned on. On the other hand, since the control signals ETR-i and ETB-i are at a low level, the transistors NT1 and NT2 of the R and B pixel circuits P are turned off.

Next, the control signals VMOL-G and VFIM-G supplied to the switching circuit 25 are at a high level, and the other control signals are at a low level. Therefore, as shown in FIG. 10, the switches Sb2 and Sb5 of the switch group SWB are turned on.
At this time, the applied voltage VF is the measurement signal F as a path of the anode of the input / output terminal T4 → switch Sb5 → data line 14 (B) corresponding to the pixel circuit of B color → transistor NT1 → transistor N1 → OLED element 11. Applied. Further, the voltage VM of the anode of the OLED element 11 is, as the signal to be measured M, the anode of the OLED element 11 → the transistor NT2 → the potential line 17 (B) corresponding to the B color pixel circuit → the switch Sb2 → the input / output terminal T3. Retrieved by route.

  FIG. 11B shows a simplified circuit for measuring characteristics of the OLED element 11. As shown in this figure, the measurement signal F (VF) is supplied through the input / output terminal T4, and the signal under measurement M (VM) is output through the input / output terminal T3. In addition, an ammeter is provided in the path of the input / output terminal T4, and current is measured. Thereby, the voltage-current characteristic of the OLED element 11 is measured.

  In the second mode, when the characteristics of the OLED element 11 of the G color pixel circuit are measured, the measurement signal F and the signal under measurement M are input and output using the data line 14 (B) and the potential line 17 (B). The number of wirings can be reduced by using both the measurement wiring and the driving wiring. Further, the measurement signal F and the signal under measurement M were input / output using the two input / output terminals T3 and T4. As a result, it is not necessary to provide a measurement input / output terminal separately from the drive.

  As described above, in this embodiment, by using the data line 14 and the potential line 17 of each pixel circuit P adjacent to each other, the measurement signal (F) and the measured signal can be obtained without adding the input / output terminals T1 to Tn. A signal (M) is transmitted. Therefore, it is not necessary to connect the measuring device to the measurement input / output terminal to execute signal transmission / reception, and the characteristic measurement can be performed using the input / output terminals T1 to Tn used in the drive mode. According to this configuration, even after the electro-optical device 1 is completed, the characteristics of the driving transistor NH1 and the OLED element 11 can be measured, and correction can be performed so that the luminance becomes uniform based on the measurement result.

  Further, since the measurement process is selectively performed on the pixel circuits P selected by the measurement target selection unit 54 among all the pixel circuits P, the measurement process is uniformly performed on all the pixel circuits P in the pixel region A. There is an advantage that the time required for the measurement process is shortened as compared with the configuration. The reduction of the measurement processing time means that a sufficient time can be secured for the original driving of the OLED element 11 (driving according to the gradation data d) in the driving mode. Therefore, according to the present embodiment, the OLED element 11 can emit light with a sufficient light emission amount.

  By the way, in the second mode of the measurement mode, the OLED element 11 emits light when current is supplied during the measurement process as shown in FIG. 10 and FIG. Therefore, for example, in the configuration in which all the pixel circuits P are subjected to the measurement process regardless of the gradation data d, the OLED element 11 that has been turned off in the drive mode emits light during the measurement process in the vertical blanking period. In particular, the gradation difference of the OLED element 11 becomes significant between the drive mode and the measurement mode. On the other hand, in the present embodiment, the pixel circuit P having a small gradation value GR (that is, the pixel circuit P having a small light emission amount) is not subjected to the measurement process, and the pixel circuit P having a large gradation value GR (that is, the light emission). A measurement process is selectively performed on the pixel circuit P) having a large amount. That is, since the OLED element 11 that has emitted light with a light emission amount exceeding a predetermined value in the driving mode only emits additional light during the measurement process, it is difficult for the user to perceive the light emission of the OLED element 11 in the measurement process. There are advantages.

<B: Second Embodiment>
Next, a second embodiment of the present invention will be described. In the first embodiment, the configuration in which the threshold value TH serving as a reference for selection by the measurement target selection unit 54 is a fixed value is exemplified. On the other hand, in the present embodiment, the threshold value TH is variably controlled.

  Whether the light emission of the OLED element 11 associated with the measurement process is easily perceived by the user is displayed by the illuminance of the environment in which the electro-optical device 1 is used (hereinafter referred to as “environmental illuminance”) or the electro-optical device 1. It depends on the brightness of the image (hereinafter referred to as “image brightness”). In other words, the light emission in the measurement mode is clearly perceived by the user when the ambient illuminance or image brightness is low (when dark), but is not noticeable when the ambient illuminance or image brightness is high (when bright). It is. Therefore, as exemplified in the following embodiments, a configuration is employed in which the threshold value TH is variably controlled based on the result of detecting the environmental illuminance and the image brightness.

<B-1: First aspect>
FIG. 12 is a block diagram illustrating a configuration of the measurement target selection unit 54 of the electro-optical device 1 according to the first aspect. As shown in the figure, the measurement target selection unit 54 includes a brightness specifying unit 541, a threshold setting unit 544A, and a comparison unit 546.

  The brightness specifying unit 541 is a means for specifying the image brightness L1. A circuit that calculates the average value of the gradation values GR of the plurality of pixel circuits P as the image brightness L1 is suitably employed as the brightness specifying unit 541. For example, the brightness specifying unit 541 displays the average value of the gradation values GR of all the pixel circuits P belonging to the pixel area A and the average value of the gradation values GR of the pixel circuits P belonging to a specific part of the pixel area A as an image. It is specified as lightness L1. The brightness specifying unit 541 may calculate the average value of the gradation values GR for one vertical scanning period (frame period), or may calculate the average value of the gradation values GR over a plurality of vertical scanning periods. Also good. For example, a means for specifying the number of gradation values GR exceeding the reference value as the image brightness L1 may be employed as the brightness specifying unit 541.

  The threshold setting unit 544A is means for setting the threshold TH based on the image brightness L1 specified by the brightness specifying unit 541. More specifically, the threshold setting unit 544A sets the threshold TH such that the threshold TH increases as the image brightness L1 decreases (the threshold TH decreases as the image brightness L1 increases). For example, the threshold setting unit 544A searches and outputs the threshold TH corresponding to the image brightness L1 specified by the brightness specifying unit 541 from a table in which the image brightness L1 and the threshold TH are associated with each other. Note that a circuit that calculates the threshold value TH based on a predetermined arithmetic expression using the image brightness L1 as an argument may be employed as the threshold value setting unit 544A.

  The comparison unit 546 compares the gradation value GR sequentially supplied from the gradation detection unit 52 with the threshold value TH set by the threshold value setting unit 544A, and performs a measurement process on the pixel circuit P in which the gradation value GR exceeds the threshold value TH. Select as the target of Since the threshold value TH increases as the image brightness L1 decreases, the number of pixel circuits P to be subjected to measurement processing decreases. In other words, the higher the image brightness L1, the greater the number of pixel circuits P to be measured. Therefore, the unevenness of gradation of each OLED element 11 is ensured by efficiently ensuring the number of pixel circuits P to be subjected to the measurement process while maintaining the state in which the light emission associated with the measurement process is not easily perceived by the user. Can be effectively suppressed.

<B-2: Second aspect>
FIG. 13 is a block diagram illustrating a configuration of the measurement target selection unit 54 according to the second aspect. As shown in the figure, the measurement target selection unit 54 includes an illuminance measurement unit 542, a threshold setting unit 544B, and a comparison unit 546.

  The illuminance measuring unit 542 measures the environmental illuminance L2 of the electro-optical device 1. An illuminance sensor that measures the illuminance around the electro-optical device 1 and the illuminance on the display surface of the electro-optical panel 10 as the environmental illuminance L 2 is suitably employed as the illuminance measuring unit 542. The illuminance measuring unit 542 is installed, for example, in the vicinity of the display surface of the electro-optical panel 10 or in the peripheral part (frame-shaped housing) of the electro-optical panel 10. Further, the illuminance measuring unit 542 may be installed at a position separated from the electro-optical device 1 such as a wall surface of a room space where the electro-optical device 1 is installed or a vicinity of an observer who visually recognizes a display image of the electro-optical device 1. .

  The threshold setting unit 544B is means for setting the threshold TH based on the environmental illuminance L2 measured by the illuminance measuring unit 542. For example, the threshold setting unit 544B sets the threshold TH such that the threshold TH increases as the environmental illuminance L2 decreases (the threshold TH decreases as the environmental illuminance L2 increases). Similarly to the threshold setting unit 544A of FIG. 12, the threshold setting unit 544B may be a means for specifying the threshold TH corresponding to the environmental illuminance L2 from the table, or a predetermined arithmetic expression using the environmental illuminance L2 as an argument. A means for calculating the threshold TH based on the threshold may be used.

  The comparison unit 546 compares the gradation value GR of each pixel circuit P with the threshold value TH set by the threshold value setting unit 544B, and selects the pixel circuit P whose gradation value GR exceeds the threshold value TH as a measurement processing target. Since the threshold value TH increases as the ambient illuminance L2 decreases, the number of pixel circuits P to be measured decreases. In other words, the higher the ambient illuminance L2, the greater the number of pixel circuits P that are the objects of measurement processing. Therefore, as in the first aspect, it is possible to efficiently secure the number of pixel circuits P to be subjected to the measurement process while maintaining a state in which light emission associated with the measurement process is not easily perceived by the user. It is.

<B-3: Third aspect>
FIG. 14 shows a third mode in which the first mode and the second mode are combined. As shown in the figure, the measurement target selection unit 54 includes a brightness specifying unit 541, an illuminance measurement unit 542, a threshold setting unit 544C, and a comparison unit 546. The configurations and functions of the lightness specifying unit 541 and the illuminance measuring unit 542 are the same as those in the first mode and the second mode.

  The threshold setting unit 544C controls the threshold TH based on the image brightness L1 specified by the brightness specifying unit 541 and the environmental illuminance L2 measured by the illuminance measuring unit 542. For example, the threshold setting unit 544C increases the threshold TH as the image brightness L1 or the environmental illuminance L2 is lower. Similar to the first mode and the second mode, the comparison unit 546 selects the pixel circuit P in which the gradation value GR exceeds the threshold value TH as a measurement processing target.

  In the configuration of FIG. 14 as well, the number of pixel circuits P to be subjected to measurement processing decreases as the image brightness L1 and environmental illuminance L2 decrease. Therefore, it is possible to efficiently secure the number of pixel circuits P to be subjected to measurement processing while maintaining a state in which light emission associated with the measurement processing is hardly perceived by the user.

<C: Modification>
Various modifications are added to the above-described embodiments. Specific modifications are as follows. In addition, the structure which combined each following aspect suitably is also employ | adopted.

(1) In the embodiment, the configuration that suppresses the difference in gradation of the OLED element 11 between the drive mode and the measurement mode by selectively executing the measurement process according to the gradation data d has been exemplified. On the other hand, in the first mode in which the characteristics of the driving transistor NH1 are measured, as shown in FIG. 9, since the supply of current is cut off by turning off the transistor N1, the OLED element 11 does not emit light. Therefore, only from the viewpoint of suppressing the difference in gradation of the OLED element 11 between the drive mode and the measurement mode, only the second mode is sufficient to limit the object of the measurement process according to the gradation data d. That is, in the first mode, the measurement process may be sequentially performed on all the pixel circuits P. For example, in the first mode, the first row, the second row,..., The m-th row are subjected to measurement processing in order, while in the measurement processing for each row, all the pixel circuits P belonging to the row are simultaneously processed. Instead of measuring, a configuration is adopted in which measurement is performed in the order of the R pixel circuit P, the G pixel circuit P, and the B pixel circuit P. In other words, three pixel circuits P in each row are selected to be the object of measurement processing, and the measurement is repeated three times by shifting the pixel circuit to be measured. In this example, the measurement is performed three times, but more generally, measurement is performed every N (N is a natural number of 2 or more) pixel circuits P, and the pixel circuit P to be measured is shifted. The measurement may be repeated N times. However, from the viewpoint of shortening the time required for the measurement mode, there is a configuration in which the measurement process is selectively executed according to the gradation data d in both the first mode and the second mode as in the embodiment. Is preferred.

(2) In the above embodiment, a configuration in which the common measurement signal F is supplied to each pixel circuit P (that is, the pixel circuit P to be subjected to measurement processing has the same gradation regardless of the gradation data d in the second mode). However, a configuration in which the measurement signal F is made different according to the gradation data d is also employed. For example, a configuration is adopted in which the measurement unit 56 controls the measurement signal F so that the voltage value of the measurement signal F becomes lower as the lower gradation is designated by the gradation data d. That is, as the low gradation is designated by the gradation data d, the OLED element 11 is controlled to a low gradation (dark gradation) in the measurement mode. For example, when the gradation value GR1 exceeding the threshold value TH is designated by the gradation data d, the measurement is performed as compared with the case where the gradation value GR2 exceeding the gradation value GR1 (and thus exceeding the threshold value TH) is designated. The measurement signal F is generated so that the gradation of the OLED element 11 at the time of processing becomes a low gradation. According to the above configuration, the difference between the gradation of the OLED element 11 in the drive mode and the gradation of the OLED element 11 in the measurement mode (second mode) can be further reduced.

(3) The data signal D may be corrected according to the presence or absence of measurement processing in the measurement mode. For example, the OLED element 11 is driven in the drive mode when the gradation when the OLED element 11 of the pixel circuit P selected as the measurement processing target is driven in the drive mode is not selected. A configuration is adopted in which the data signal D is adjusted so that the gray level is lower than the current gray level. For example, the light emission amount in the drive mode of the OLED element 11 to be measured is the light emission amount obtained by subtracting the light emission amount in the measurement mode from the light emission amount corresponding to the gradation data d (corrected gradation data dh). Thus, the data signal D is adjusted according to the presence or absence of the measurement process. The adjustment of the data signal D may be executed by the data line driving circuit 24 or may be realized by the correction circuit 30 correcting the gradation data d.

  According to the above configuration, the sum of the light emission amount in the drive mode and the light emission amount in the measurement mode is adjusted to the original light emission amount according to the gradation data d. Therefore, it is possible to make it difficult for the user to perceive the light emission of the OLED element 11 in the measurement mode. Note that when the OLED element 11 is driven to a low gradation (dark gradation) in the drive mode, the light emission of the OLED element 11 in the measurement mode is particularly noticeable to the user. Therefore, the light emission amount of the OLED element 11 in the drive mode is reduced only when the gradation specified by the gradation data d (or the corrected gradation data dh) is smaller than a predetermined threshold (variable or fixed). A configuration is also adopted.

(4) The configuration in which the data line 14 is used for the transmission of the data signal D and the transmission of the measurement signal F and the signal under measurement M is not an essential requirement in the present invention. That is, a configuration in which wiring for transmitting the measurement signal F and the signal under measurement M to each pixel circuit P is formed separately from the data line 14 is also employed.

(5) The transistors NT1 and NT2 may be turned on / off by the power supply voltages VEL-R, VEL-G, and VEL-B. For example, the pixel circuit P shown in FIG. 15 can be employed. In this case, since the power supply voltage VEL-R is supplied to the gates of the transistors NT1 and NT2, on / off of the transistors NT1 and NT2 can be controlled depending on whether the power supply voltage VEL-R is valid.

(6) In the first mode of the embodiment, the source voltage VS of the drive transistor NH1 is output as the signal to be measured M. However, in addition to this, the drain voltage may be measured. For example, the pixel circuit P shown in FIG. 16 can be employed. In this case, a measurement wiring 18 is formed along the potential line 17, and a P-channel transistor P2 is provided between the wiring 18 and the drain of the driving transistor NH1. A control signal XETP-1 is supplied to the gate of the transistor P2 via the control line L6. By setting the control signal XETP-1 to the low level, the drain voltage of the drive transistor NH1 can be taken out as the signal to be measured M through the wiring 18. FIG. 17 is a schematic diagram showing a simplified pixel circuit P in the first mode. In this example, since there are four measurement signals F and signals under measurement M, four input / output terminals are used.
Here, for the row to be measured, the control signals XEP and XETP are set to the low level and the control signal EW is set to the high level to turn on the transistors P1, P2, and N2 to N4. For the selected row, the transistor P2 needs to be turned off, but the logic level of the control signal may be inverted for the other transistors to turn off the transistors P1 and N2 to N4. In this case, when a leak current flows through the wiring 18 in the transistor P2 in the non-selected row, the measurement accuracy of the drain voltage of the drive transistor NH1 to be measured is lowered. If the leakage current when the gate of the transistor P2 in the non-selected row is at a high level (off state) tends to increase as the drain-source voltage increases, the leakage current is reduced by decreasing the drain-source voltage. It is possible. One of the source and the drain of the transistor P2 is connected to the transistor P1 in the pixel, and the other is connected to the measured line 18. When the measured line 18 has a voltage close to a high level, the drain current of the transistor P2 may be set to a high level to reduce the leakage current in order to reduce the source-drain voltage of the transistor P2. In this case, the control signal XEP supplied to the non-selected row may be set to a low level to turn on the transistor P1. However, when giving priority to the measurement accuracy of the gate-source voltage of the drive transistor NH1, it is preferable to set the control signal XEP to high level in order to reduce the leakage current of the drive transistor NH1 in the non-selected row. The logic level of the control signal XEP in the non-selected row may be appropriately determined according to the measurement accuracy requirement. In order to reduce the leakage current of each transistor, it is also effective to configure each transistor with a series transistor having a common gate, that is, a so-called dual gate transistor.
In short, not only the transistor P2, but also the transistors P2, NT1, NT2, N3, and N4 in the non-selected rows connected to the measurement line and the line to be measured not only turn the gate off, but also the source-drain By reducing the voltage between them, the leakage current can be reduced, and as a result, the measurement accuracy can be increased. Therefore, it is preferable to timely control other control signals of non-selected rows. That is, the control method for the non-selected rows may be changed depending on which measurement value is to be improved. Note that since one of the transistors N2 is connected only to the gate of the driving transistor NH1, no leakage depending on the source-drain voltage occurs.

(7) In the embodiment, the characteristics of the driving transistor NH1 and the OLED element 11 are individually measured, but these may be measured simultaneously. FIG. 18 shows a simplified schematic diagram of the pixel circuit P in the simultaneous measurement. In this case, the transistor N1 is turned on, and a drive current is supplied from the drive transistor NH1 to the OLED element 11. Simultaneous measurement can reduce the measurement time. Note that simultaneous measurement and individual measurement may be mixed.

(8) Although the reference potential lines Lr, Lb, and Lg are provided in the switching circuit 25 in the embodiment, these are provided in the data line driving circuit 24 and input / output terminals corresponding to the data line 14 and the potential line 17 are provided. Also good. For example, as shown in FIG. 19, the data signal D and the R reference potential REF-R may be output from the input / output terminals Ta and Tb. Since the data line 14 and the potential line 17 are formed adjacent to each other, and the gate-source voltage of the driving transistor NH1 is determined by the difference between the potential of the data line 14 and the potential of the potential line 17, in-phase noise is superimposed on them. However, the noise component can be canceled as the difference. Therefore, the electro-optical device 1 that is resistant to noise can be provided.

(9) The measurement process may be executed in a period other than the vertical blanking period. For example, the drive mode may be assigned to a part of the vertical scanning period, and the measurement mode may be assigned to the remaining period of the vertical scanning period. The frequency of the measurement process is also arbitrary. For example, in addition to the configuration in which the measurement process is performed every one or a plurality of vertical blanking periods, the configuration in which the measurement process is performed immediately after the electro-optical device 1 is turned on or every predetermined time is also employed.

(10) In each embodiment, an active matrix type electro-optical device including a transistor for driving the OLED element 11 is illustrated, but a passive matrix type electro-optical device in which the pixel circuit P does not have these switching elements. The present invention also applies to an apparatus.

(11) In each embodiment, the electro-optical device 1 using the OLED element 11 that is a current-driven self-luminous element has been illustrated, but other current-driven electro-optical elements and voltage-driven electro-optical elements are used. The present invention is also applied to the electro-optical device used. For example, liquid crystal display devices, display devices using inorganic EL elements, field emission displays (FEDs), surface-conduction electron emission displays (SEDs), ballistic electron emission displays (BSD) The present invention is also applied to various electro-optical devices such as a display device using a ballistic electron surface emitting display), a light emitting diode, or a writing head of an optical writing type printer or an electronic copying machine.

<D: Application example>
Next, an electronic apparatus to which the electro-optical device according to the invention is applied will be described. FIG. 20 is a perspective view showing the configuration of a mobile personal computer that employs the electro-optical device 1 according to each of the above embodiments as a display device. The personal computer 2000 includes the electro-optical device 1 as a display device and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002. Since the electro-optical device 1 uses the OLED element 11, it is possible to display an easy-to-see screen with a wide viewing angle.

  FIG. 21 shows a configuration of a mobile phone to which the electro-optical device 1 according to each of the above embodiments is applied. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the electro-optical device 1 as a display device. By operating the scroll button 3002, the screen displayed on the electro-optical device 1 is scrolled.

  FIG. 22 shows a configuration of a personal digital assistant (PDA) to which the electro-optical device 1 according to each of the above embodiments is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and the electro-optical device 1 as a display device. When the power switch 4002 is operated, various types of information such as an address book and a schedule book are displayed on the electro-optical device 1.

  The electronic apparatus to which the electro-optical device according to the invention is applied includes, in addition to those shown in FIGS. 20 to 22, a digital still camera, a television, a video camera, a car navigation device, a pager, an electronic notebook, electronic paper, Examples include calculators, word processors, workstations, videophones, POS terminals, printers, scanners, copiers, video players, devices equipped with touch panels, and the like.

1 is a block diagram illustrating a configuration of an electro-optical device according to a first embodiment of the invention. FIG. It is a circuit diagram which shows the structure of a pixel circuit. 6 is a timing chart illustrating an operation of the electro-optical device in a driving mode. It is explanatory drawing which shows the state of the pixel circuit in the writing period. It is explanatory drawing which shows the state of the pixel circuit in the light emission period. It is a block diagram which shows the structure of a measurement control circuit. It is a circuit diagram which shows the structure of a switching circuit and its peripheral circuit. It is a truth table of various control signals in measurement mode It is explanatory drawing which shows operation | movement when the pixel circuit used as the measuring object in 1st mode is G color. It is explanatory drawing which shows operation | movement when the pixel circuit used as the measuring object in 2nd mode is G color. It is explanatory drawing which simplifies and shows the pixel circuit in a measurement mode. It is a block diagram which shows the measuring object selection part which concerns on the 1st aspect of 2nd Embodiment. It is a block diagram which shows the measuring object selection part which concerns on the 2nd aspect of 2nd Embodiment. It is a block diagram which shows the measuring object selection part which concerns on the 3rd aspect of 2nd Embodiment. It is a circuit diagram which shows the example of the pixel circuit which concerns on a modification. It is a circuit diagram which shows the example of the pixel circuit which concerns on a modification. It is explanatory drawing which simplifies and shows the pixel circuit of the modification in 1st mode. It is explanatory drawing which simplifies and shows the pixel circuit of the modification in measurement mode. It is a block diagram for demonstrating the input-output terminal which concerns on a modification. It is a perspective view which shows the structure of the personal computer to which this invention is applied. It is a perspective view which shows the structure of the mobile telephone to which this invention is applied. It is a perspective view which shows the structure of the portable information terminal to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electro-optical apparatus, 11 ... OLED element, 14 ... Data line, 17 ... Potential line, 24 ... Data line drive circuit, 25 ... Switching circuit, 50 ... Measurement control circuit, 52 ... Tone detection part, 54 ... Measurement object Selection unit 56 ... Measurement unit 58 ... Measurement history memory P ... Pixel circuit D ... Data signal F ... Measurement signal M ... Measured signal Lr, Lg, Lb ... Reference potential line T1-Tn ... On Output terminal, NH1... Drive transistor, d... Gradation data, Dh... Correction data, dh.

Claims (13)

An electro-optical device in which a plurality of pixels each including an electro-optical element is connected to each data line,
A signal generation unit that generates a data signal corresponding to gradation data designating the gradation of each electro-optic element and outputs the data signal to the data line;
A measurement object selection unit that selects an electro-optic element whose gradation exceeding the threshold is specified by gradation data;
A measurement process for driving the electro-optical element by output of a measurement signal and obtaining a signal under measurement indicating characteristics of the electro-optical element when driven by the measurement signal is selected from the plurality of electro-optical elements. An electro-optical device comprising: a measuring unit that executes the electro-optical element selected by the unit. A storage unit for storing measurement history data indicating whether or not the measurement process has been performed for each of the electro-optic elements;
The measurement unit has not yet performed measurement processing based on the measurement history data stored in the storage unit when the number of electro-optical elements whose gradation specified by the gradation data exceeds a threshold exceeds a predetermined number. The electro-optical device according to claim 1, wherein a measurement process is performed on the electro-optical element. The measurement unit performs measurement when a first gradation exceeding the threshold is specified by gradation data, compared to a case where a second gradation exceeding the first gradation is specified by gradation data. The electro-optical device according to claim 1, wherein the measurement signal is generated so that the electro-optical element during processing has a low gradation. The signal generation unit corrects the data signal so that the gray level when the electro-optic element selected by the measurement target selection unit is driven by the supply of the data signal is lower than that when the data signal is not selected. The electro-optical device according to claim 1. The electro-optical device according to claim 1, further comprising a threshold setting unit that variably controls the threshold. A brightness specifying unit for specifying the brightness of an image output by the plurality of pixels;
The electro-optical device according to claim 5, wherein the threshold setting unit controls the threshold according to the lightness specified by the lightness specifying unit. An illuminance measurement unit that measures the environmental illuminance of the electro-optical device
The electro-optical device according to claim 5, wherein the threshold setting unit controls the threshold according to environmental illuminance measured by the illuminance measuring unit. A plurality of input / output terminals provided corresponding to the data lines;
In the drive mode, the data signal generated by the signal generation unit is supplied to the data line via the input / output terminal, and in the measurement mode, the data line corresponding to the pixel selected by the measurement target selection unit and the data An input / output unit for inputting / outputting the measurement signal and the signal under measurement via the input / output terminal corresponding to the data line adjacent to the line;
The pixel captures a data signal supplied via the data line in the drive mode, and captures the measurement signal via the data line and a data line adjacent to the data line in the measurement mode. The electro-optical device according to claim 1, further comprising: a selection unit that outputs a signal under measurement.   An electronic apparatus comprising the electro-optical device according to claim 1. A method of driving an electro-optical device including a plurality of electro-optical elements,
While driving each electro-optic element by outputting a data signal corresponding to gradation data designating the gradation of each electro-optic element,
Select an electro-optic element whose gradation that exceeds the threshold is specified by the gradation data,
A measurement process for driving the electro-optical element by output of a measurement signal and obtaining a signal under measurement indicating characteristics of the electro-optical element when driven by the measurement signal is performed in the selected electric optical element among the plurality of electro-optical elements. An electro-optical device driving method comprising: performing the method on an optical element. Storing measurement history data indicating whether or not the measurement process has been performed for each electro-optic element in the storage unit;
When the number of electro-optic elements whose gradation specified by the gradation data exceeds the threshold exceeds a predetermined number, measurement is performed for electro-optic elements that have not yet been measured based on the measurement history data stored in the storage unit. The method according to claim 10, wherein the process is executed. In the measurement process, when the first gradation exceeding the threshold is specified by the gradation data, compared to the case where the second gradation exceeding the first gradation is specified by the gradation data, The method of driving an electro-optical device according to claim 10 or 11, wherein the measurement signal is generated so that the electro-optical element at the time of measurement processing has a low gradation. The data signal is corrected so that a gradation when the electro-optic element selected by the measurement target selection unit is driven by supplying a data signal is lower than that when the electro-optic element is not selected. Item 13. The driving method for an electro-optical device according to any one of Items 10 to 12.

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