JP2007206139A - Method of driving unit circuit, light emitting device and method of driving same, data line driving circuit, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a light emitting element emit light at the light quantity correctly meeting the gradation shown by image data regardless of the operating characteristics of a drive transistor. <P>SOLUTION: A measuring potential V1 is determined by measuring a potential Vg of a gate of a drive transistor Tdr while passing a constant current I1 in the route from the source to the drain of the drive transistor Tdr in the diode-connected state of the drive transistor Tdr at the time of driving unit circuits P (PA, PB) equipped with the light emitting element 11 emitting light at the light quantity meeting the level of a drive current Iel and the drive transistor Tdr for supplying the drive current Iel to the light emitting element 11, and on the other hand, a measuring potential V1 is determined by measuring the potential Vg while passing a constant current I2 in the above route. The variation of the operating characteristics of the drive transistor Tdr is corrected based on the set of (I1, V1), (I2, V2) and a data signal Vdata meeting the gradation indicated by image data VDATA and is supplied to the gate of the drive transistor Tdr. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for controlling the behavior of a current-driven light emitting element.

  A current-driven light-emitting element is an element that is driven by a current and emits light with a light amount corresponding to the level of the drive current. Typically, it receives a signal indicating a gradation and emits light with a light quantity corresponding to the gradation. It is used as a light source of a light emitting device. As this type of light emitting device, a plurality of unit circuits including light emitting elements are provided in a matrix, and image data indicating the gradation of each of a plurality of pixels constituting an image is received, and a plurality of unit circuits are provided according to the image data There is a display device that displays the image by driving.

  In this type of display device, the light emitting element is a pixel which is a unit constituting an image. Therefore, hereinafter, a unit circuit of this type of display device is also referred to as a “pixel circuit”. The pixel circuit is a circuit that receives a signal corresponding to the image data and controls the light amount of the internal light emitting element, and includes a driving transistor that generates a driving current of a level corresponding to the signal. The driving transistor is a transistor that outputs from the drain a current corresponding to the voltage Vgs between the source and the gate to which the power supply potential is supplied. In the pixel circuit, this current is used as the driving current.

Since the operating characteristics of the drive transistor vary due to individual differences, in the display device described above, there is a possibility that the gradation of the displayed image varies between pixels. Thus, for example, Patent Document 1 discloses a technique for correcting (compensating) variations in threshold voltages of drive transistors.
US Pat. No. 6,229,506

However, the variation in the operating characteristics of the drive transistor includes variations other than the threshold voltage variation such as mobility. Therefore, even if the variation in threshold voltage can be sufficiently corrected, it is not sufficient. In the first place, even if the variation in the operating characteristics of the drive transistor can be sufficiently corrected, the light-emitting element cannot always emit light with a light amount that correctly corresponds to the gradation indicated by the image data.
The present invention has been made in view of such circumstances, and drives a unit circuit capable of causing a light-emitting element to emit light with a light amount that corresponds to the gradation indicated by image data, regardless of the operating characteristics of the drive transistor. An object of the present invention is to provide a method, a light emitting device and a driving method thereof, a data line driving circuit, and an electronic device.

  Since the driving transistor exhibits a square characteristic in the saturation region, its operating characteristic can be estimated if at least two sets of the voltage Vgs of the driving transistor and the driving current at that time are known. If the operating characteristics of the driving transistor are known, variations among the operating characteristics of the driving transistor can be corrected. The present invention solves the above-described problems based on such a concept, and the specific configuration thereof is as described below.

A unit circuit driving method (first driving method) according to the present invention includes a light emitting element that emits light with a light amount corresponding to a level of a driving current, and a driving transistor that supplies the driving current to the light emitting element. A driving method of a unit circuit for supplying a data signal for determining a level of the driving current to control a light amount of the light emitting element using the data signal corresponding to image data indicating gradation, The voltage between the source and gate of the driving transistor is measured as the first voltage while flowing a first current from the source to the drain of the driving transistor in a state where the gate and drain of the transistor are electrically connected, While the gate and drain of the driving transistor are electrically connected, the second current is passed from the source to the drain of the driving transistor A voltage between a source and a gate of the dynamic transistor is measured as a second voltage, and the set of the first current and the first voltage and the first voltage are set so that the light amount of the light emitting element becomes a gradation indicated by the image data. Based on a set of two currents and the second voltage, a variation in operating characteristics of the driving transistor is corrected to generate the data signal corresponding to the gradation indicated by the image data, and the data signal is output from the driving transistor. It supplies to a gate, It is characterized by the above-mentioned.
In the first driving method, in a state where the driving transistor is diode-connected, a current (first current and second current) flows from the source to the drain of the driving transistor while flowing a voltage (first voltage) between the source and gate of the driving transistor. 1 voltage and the second voltage), a set of the first current and the first voltage and a set of the second current and the second voltage are obtained, and the gradation indicated by the image data based on these two sets A data signal corresponding to the signal is generated and supplied to the gate of the driving transistor. In the generation of the data signal, the variation in the operating characteristics of the driving transistor is corrected based on the above concept. That is, the data signal is a signal that causes the drive transistor to be supplied to generate a drive current at a level that causes the light emitting element to emit light with a light amount corresponding to the gradation indicated by the image data. Therefore, according to the first driving method, it is possible to cause the light emitting element to emit light with a light amount that correctly corresponds to the gradation indicated by the image data, regardless of the operating characteristics of the driving transistor.
As a method for obtaining the above set, a method of measuring the voltage Vgs of the driving transistor while supplying a constant current from the source to the drain of the driving transistor, and a method of measuring the voltage Vgs of the driving transistor from the source of the driving transistor while keeping the voltage Vgs of the driving transistor constant. There is a method of measuring the current flowing toward the drain. Either method requires wiring for measuring voltage or current, but in the latter method, the parasitic capacitance of the wiring affects the voltage measurement, and the measurement accuracy is lowered. On the other hand, in the first driving method, since the former method is adopted, the parasitic capacitance does not affect the current measurement, and the measurement accuracy can be maintained high. That is, according to the first driving method, it is possible to cause the light emitting element to emit light with an amount of light that accurately corresponds to the gradation indicated by the image data, regardless of the operating characteristics of the driving transistor.
The first driving method is premised on a circuit provided with “wiring for supplying a data signal to the gate of a driving transistor” as a unit circuit to be driven. By using this wiring, it is possible to flow a constant current from the source to the drain of the driving transistor, or to measure the voltage between the source and gate of the driving transistor. A unit circuit provided with this wiring is common, and for example, is widely used as a pixel circuit of a display device. Therefore, according to the first driving method, it is possible to obtain the various effects described above without changing a general unit circuit.
In the first driving method, the operation of the driving transistor is based not only on the set of the first current and the first voltage and the set of the second current and the second voltage but also on other sets required in the same manner as these sets. A driving method for correcting the variation in characteristics is included. That is, the number of sets based on correcting variations in the operating characteristics of the drive transistors may be three or more. The more pairs that are based, the more accurate the correction.
The first driving method includes a method of dividing the operation characteristics of the driving transistor into a plurality of gradation ranges and correcting only one of the gradation ranges, and a method of correcting each gradation range individually. . As the former method, only for the gradation range between the first gradation and the second gradation, the driving transistor is controlled based on the combination of the first current and the first voltage and the combination of the second current and the second voltage. A method for correcting variations in operating characteristics can be exemplified. As the latter method, for a certain gradation range, the variation in the operating characteristics of the driving transistor is corrected based on a plurality of sets, and for another gradation range, the plurality of sets are not completely the same. A method for correcting variations in the operating characteristics of the drive transistors based on a plurality of sets can be exemplified.
In addition, the “variation in the operating characteristics of the driving transistor” means a difference in operating characteristics of the driving transistor to be measured from the reference operating characteristics (for example, ideal operating characteristics). When the operation characteristics of the drive transistor are the reference operation characteristics, the light amount of the light emitting element becomes a gradation indicated by the image data.

  In the first driving method, in the step of converting the image data into the data signal, the image data is converted based on the set of the first current and the first voltage and the set of the second current and the second voltage. A voltage of the data signal corresponding to the maximum gradation and a voltage of the data signal corresponding to the minimum gradation of the image data are generated, and based on the generated voltage, variations in the operating characteristics of the driving transistor are corrected. Then, the data signal corresponding to the gradation indicated by the image data may be generated.

Another unit circuit driving method (second driving method) according to the present invention includes a light emitting element that emits light with a light amount corresponding to a level of a driving current, a driving transistor that supplies the driving current to the light emitting element, and the driving. The drive through the data line to a unit circuit comprising a first transistor provided between the gate and drain of the transistor and a second transistor provided between the gate or drain of the drive transistor and the data line A method of driving a unit circuit, wherein a data signal for determining a current level is supplied every predetermined period, and the light quantity of the light emitting element is controlled using the data signal corresponding to image data indicating gradation. In the period, in the measurement period in which the first transistor and the second transistor are turned on, the source to the drain of the drive transistor The voltage of the data line is measured using the voltage between the source and the gate of the driving transistor as the first voltage while the first current is applied toward the first direction, and the first voltage is applied from the source to the drain of the driving transistor in the measurement period. While the two currents are flowing, the voltage of the data line is measured as a second voltage between the source and the gate of the driving transistor, and the first light source has a gray level indicated by the image data. Based on the set of the current and the first voltage and the set of the second current and the second voltage, the data signal corresponding to the gradation indicated by the image data is corrected by correcting the variation in the operating characteristics of the drive transistor. And supplying the data signal to the data line during a writing period in which the first transistor is turned off and the second transistor is turned on. Supplied to the gate of the driving transistor, and wherein the.
According to this driving method, the same effects as those obtained by the first driving method can be obtained. In addition, according to this driving method, since the above measurement and correction are performed every predetermined period, not only static variation such as variation in operating characteristics of the driving transistor but also temperature change Also, dynamic variations due to factors such as deterioration can be corrected appropriately.

A driving method of a light emitting device according to the present invention corresponds to a data line, a signal line provided to be paired with the data line, a plurality of scanning lines, and an intersection of the data lines and the plurality of scanning lines. Each of the plurality of pixel circuits, and each of the plurality of pixel circuits includes a light emitting element that emits light with a light amount corresponding to a level of the driving current, and a driving transistor that supplies the driving current to the light emitting element. A first transistor provided between a gate and a drain of the driving transistor, a second transistor provided between a gate of the driving transistor and the data line, a gate of the driving transistor, and the signal line And a third transistor provided between each of the plurality of pixel circuits, wherein each of the plurality of pixel circuits is sequentially selected for a corresponding scanning line only in a horizontal scanning period. In each of the plurality of pixel circuits, in the first horizontal scanning period in which another pixel circuit different from the pixel circuit is selected, the first transistor and the third transistor are turned on, and the second transistor is turned off. The voltage of the data line is measured as the voltage between the source and the gate of the driving transistor while the first current flows from the source to the drain of the driving transistor, and the source of the driving transistor is measured. The voltage of the data line is measured as a second voltage between the source and gate of the drive transistor while a second current is passed from the drain to the drain, and the light amount of the light emitting element becomes a gradation indicated by the image data As described above, based on the set of the first current and the first voltage and the set of the second current and the second voltage, the drive transistor In the second horizontal scanning period in which the pixel circuit is selected, the first transistor and the third transistor are made to generate the data signal corresponding to the gradation indicated by the image data by correcting the variation in the operation characteristics of The data transistor is turned off, the second transistor is turned on, and the data signal is supplied to the data line.
According to this driving method, the same effects as those obtained by the first driving method can be obtained. However, the driving target is limited to a light emitting device including a signal line provided to be paired with a data line.
In this driving method, when attention is paid to a pixel circuit corresponding to one scanning line, the voltage Vgs of the driving transistor is measured in a period outside the horizontal scanning period in which the pixel circuit is selected. Therefore, according to this driving method, compared to the case where this measurement is performed within the horizontal scanning period, the period during which the data signal is supplied to the gates of the driving transistors of the plurality of pixel circuits in the horizontal scanning period. The ratio can be increased. This leads to an improvement in light emission quality for the reasons described below.
Even when the supply of the data signal to the gate of the drive transistor is started, it takes a certain amount of time for the voltage Vgs of the drive transistor to become a voltage corresponding to the data signal. That is, from the viewpoint of improving the light emission quality, it is better to secure the time for supplying the data signal to the gate of the driving transistor as long as possible in the horizontal scanning period. On the other hand, there is a demand for a large screen and high definition in the light emitting device, and it is necessary to shorten the horizontal scanning period. Therefore, an increase in the ratio of the period during which the data signal is supplied to the gate of the driving transistor in the horizontal scanning period leads to improvement in light emission quality.

  In each of the above driving methods excluding the second driving method, when the light emitting element repeatedly emits light, not only the method of performing the above measurement and correction every time, but also a method of performing only the first time or a plurality of times, or intermittent Also included is the method of The method of performing intermittently includes a method of repeating every predetermined number of times.

A light emitting device (first light emitting device) according to the present invention includes a plurality of data lines, a plurality of scanning lines, a data line driving circuit for supplying a data signal to each of the plurality of data lines, and the plurality of data lines. And a plurality of pixel circuits provided corresponding to intersections of the plurality of scanning lines, each of the plurality of pixel circuits including a light emitting element that emits light with a light amount corresponding to a level of a driving current, and the driving current Driving transistor for supplying light to the light emitting element; a first transistor provided between the gate and drain of the driving transistor; and a second transistor provided between the gate or drain of the driving transistor and the data line. And the data line driving circuit includes a source of the driving transistor in a measurement period in which the first transistor and the second transistor are turned on. The voltage of the data line is measured using the voltage between the source and the gate of the driving transistor as the first voltage while the first current flows from the drain to the drain, and the second current flows from the source to the drain of the driving transistor. Measuring means for measuring the voltage of the data line as a second voltage between the source and the gate of the driving transistor, and so that the light quantity of the light emitting element becomes a gradation indicated by the image data. The data signal corresponding to the gradation indicated by the image data by correcting variations in operating characteristics of the driving transistor based on a set of one current and the first voltage and a set of the second current and the second voltage And a signal generation means for generating.
In the first light emitting device, during the measurement period, a voltage (first voltage and second voltage) between the source and the gate of the drive transistor while flowing current (first current and second current) from the source to the drain of the drive transistor. Voltage) is measured through the second transistor and the data line to obtain a set of the first current and the first voltage and a set of the second current and the second voltage, and based on these two sets, A data signal corresponding to the gradation indicated by the image data is generated. In this generation, variations in the operating characteristics of the drive transistor are corrected based on the above-described idea. Therefore, according to the first light emitting device, the same effect as that obtained by the first driving method can be obtained. It should be noted that the second transistor and the data line are formed in the above-described case when the first transistor is in the off state and the second transistor is in the on state, that is, when the data signal can be correctly supplied to the gate of the driving transistor. This is an element constituting “wiring for supplying a data signal to the gate of the driving transistor”.
In the first light emitting device, the data line and the wiring for supplying the data signal to the gate of the driving transistor, represented by the second transistor in the on state, are used and are predetermined from the source to the drain of the driving transistor. Value current is flowing. A pixel circuit having this wiring is general and widely used. Therefore, according to this light emitting device, various effects described above can be obtained while using a general pixel circuit.

  In the first light emitting device, the second transistor is provided between a drain of the driving transistor and the data line, and the first transistor is provided between a gate of the driving transistor and the data line, and the driving The transistor gate and drain may be connected by a path including the first transistor, the data line, and the second transistor. In this aspect, the first transistor is provided on a path between the gate and the drain of the drive transistor. That is, the first transistor is provided between the gate and the drain of the drive transistor. Therefore, various effects obtained by the first light emitting device can be obtained. Further, according to this aspect, the current of the driving transistor in which the data voltage is programmed can be read out to the data line. Since it is easy to connect an inspection circuit for inspecting circuit operation to the data line, according to this aspect, it is possible to easily inspect circuit operation.

Another light-emitting device (second light-emitting device) according to the present invention includes a plurality of data lines, a plurality of signal lines provided in pairs with the plurality of data lines, a plurality of scanning lines, and the plurality of the plurality of data lines. And a plurality of pixel circuits provided corresponding to intersections of the plurality of data lines and the plurality of scanning lines, and the plurality of pixel circuits. Each includes a light emitting element that emits light with a light amount corresponding to a level of a driving current, a driving transistor that supplies the driving current to the light emitting element, and a first transistor provided between a gate and a drain of the driving transistor. A second transistor provided between the gate of the driving transistor and the data line, and a third transistor provided between the gate of the driving transistor and the signal line, The data line driving circuit allows a first current to flow from the source to the drain of the driving transistor during a measurement period in which the first transistor and the third transistor are in an on state and the second transistor is in an off state. Meanwhile, the voltage of the data line is measured by using the voltage between the source and gate of the driving transistor as the first voltage, and the second current flows from the source to the drain of the driving transistor, and the voltage of the data line is measured. Measuring means for measuring as a second voltage between the source and gate of the driving transistor, and a set of the first current and the first voltage so that the light quantity of the light emitting element becomes a gradation indicated by the image data; Based on the set of the second current and the second voltage, the image data is corrected by correcting variations in the operating characteristics of the drive transistor. The data signal corresponding to the gray level is generated, and the data signal is supplied to the data line during a writing period in which the first transistor and the third transistor are turned off and the second transistor is turned on. And a signal generation means.
In the second light emitting device, the voltage (first voltage and second voltage) between the source and the gate of the driving transistor while flowing current (first current and second current) from the source to the drain of the driving transistor in the measurement period. Voltage) is measured through the third transistor and the signal line to obtain a first current and first voltage set and a second current and second voltage set. Based on these two sets, A data signal corresponding to the gradation indicated by the image data is generated. In this generation, variations in the operating characteristics of the drive transistor are corrected based on the above-described idea. The generated data signal is correctly supplied from the data line to the gate of the driving transistor through the third transistor that is in the ON state in the writing period. Therefore, according to the second light emitting device, the same effect as that obtained by the first driving method can be obtained.
However, in the second light emitting device, a current of a predetermined value flows from the source of the drive transistor to the drain separately from the wiring for supplying the data signal to the gate of the drive transistor, and the source and gate of the drive transistor A signal line for measuring the voltage between them is provided. Therefore, according to the second light emitting device, a general pixel circuit cannot be used as it is. Instead, in the horizontal scanning period in which the pixel circuit is selected, the ratio of the period during which the data signal is supplied to the gate of the driving transistor of the pixel circuit can be increased. Specifically, when a pixel circuit corresponding to a certain scanning line is selected and a writing period comes, the second transistor is turned on and the first transistor and the third transistor are turned off in the pixel circuit. On the other hand, if the second transistor is turned off and the first transistor and the third transistor are turned on in the pixel circuit that reaches the writing period immediately after the pixel circuit, the above ratio is obtained. Can be increased. As described above, the increase in the ratio leads to an improvement in light emission quality.

In the first light emitting device or the second light emitting device, the measuring means includes a first current source that generates the first current, a second current source that generates the second current, and the first current in the measurement period. And a selection circuit that selects and supplies the second current to the data line, and samples the voltage of the data line during a period in which the selection circuit selects the first current, and holds the sampled voltage. A first sample and hold circuit for outputting the first voltage; and a voltage of the data line is sampled during a period in which the selection circuit selects the second current, and the sampled voltage is held and the second voltage is output. And a second sample and hold circuit.
According to this aspect, the time from the start of measurement to the completion of correction can be made much shorter than when the measurement result is processed by a computer. Therefore, for example, when the light emitting element is caused to emit light repeatedly, the above measurement and correction can be performed for the driving transistor that supplies a driving current to the light emitting element before the light emitting element emits light. Therefore, according to this aspect, not only static variations such as variations in the operating characteristics of the drive transistor among individuals, but also dynamic variations due to factors such as temperature change and deterioration can be corrected appropriately. Can do. Further, according to this aspect, since the measured voltage is held by the sample and hold circuit, the configuration is not limited to the case where the measurement result is processed by the computer, and compared to the case where the measured voltage is held in the memory. Much simpler. This leads to a reduction in manufacturing costs, for example.

  In the first light-emitting device or the second light-emitting device, the signal generation unit may generate a maximum order of the image data based on the set of the first current and the first voltage and the set of the second current and the second voltage. A voltage generation unit that generates a voltage of the data signal corresponding to a tone, a voltage of the data signal corresponding to a minimum gray level of the image data, and a voltage generated by the voltage generation unit. Correction means for correcting variation in operating characteristics and generating the data signal corresponding to the gradation indicated by the image data may be provided.

  An electronic apparatus according to the present invention includes any one of the light emitting devices described above. Therefore, there is an effect obtained by the light emitting device provided.

A data line driving circuit according to the present invention includes a plurality of data lines, a plurality of scanning lines, and a plurality of pixel circuits provided corresponding to intersections of the plurality of data lines and the plurality of scanning lines, Each of the plurality of pixel circuits is provided between a light emitting element that emits light with a light amount corresponding to a level of a driving current, a driving transistor that supplies the driving current to the light emitting element, and a gate and a drain of the driving transistor. And a second transistor provided between the gate or drain of the driving transistor and the data line, and supplies a data signal to each of the plurality of data lines. A data line driving circuit, wherein the first transistor and the second transistor are turned on from a source of the driving transistor in a measurement period in which the first transistor and the second transistor are turned on. The voltage of the data line is measured using the voltage between the source and the gate of the driving transistor as the first voltage while the first current flows toward the in, and the second current is applied from the source to the drain of the driving transistor. Measuring means for measuring the voltage of the data line as a second voltage between the source and gate of the driving transistor, and the first light source so that the light quantity of the light emitting element becomes a gradation indicated by the image data. Based on the set of the current and the first voltage and the set of the second current and the second voltage, the data signal corresponding to the gradation indicated by the image data is corrected by correcting the variation in the operating characteristics of the drive transistor. And a signal generating means for generating.
According to this data line driving circuit, the voltage between the source and the gate of the driving transistor (the first voltage and the second current) while flowing current (first current and second current) from the source to the drain of the driving transistor in the measurement period. Measuring the second voltage) through the second transistor and the data line to obtain a set of the first current and the first voltage and a set of the second current and the second voltage, and based on these two sets A data signal corresponding to the gradation indicated by the image data can be generated. In this generation, variations in the operating characteristics of the drive transistor are corrected based on the above-described idea. Therefore, according to the data line driving circuit, the same effect as that obtained by the first light emitting device can be obtained.

Another data line driving circuit according to the present invention includes a plurality of data lines, a plurality of signal lines provided in pairs with the plurality of data lines, a plurality of scanning lines, and the plurality of data lines. A plurality of pixel circuits provided corresponding to the intersection of the plurality of scanning lines, and each of the plurality of pixel circuits emits light with a light amount corresponding to a level of the driving current; and the driving current A drive transistor for supplying to the light emitting element; a first transistor provided between a gate and a drain of the drive transistor; a second transistor provided between a gate of the drive transistor and the data line; Data line drive for use in a light emitting device having a third transistor provided between the gate of the drive transistor and the signal line, and supplying a data signal to each of the plurality of data lines In the measurement period in which the first transistor and the third transistor are turned on and the second transistor is turned off, a first current is passed from the source to the drain of the driving transistor, The voltage of the data line is measured using a voltage between the source and gate of the driving transistor as a first voltage, and a second current is passed from the source to the drain of the driving transistor, and the voltage of the data line is driven. Measuring means for measuring as a second voltage between the source and gate of the transistor, the set of the first current and the first voltage, and the first voltage so that the light quantity of the light emitting element becomes a gradation indicated by the image data. Based on a set of two currents and the second voltage, a variation in the operating characteristics of the driving transistor is corrected to indicate the level indicated by the image data. Signal generating means for generating the data signal corresponding to the data line, and supplying the data signal to the data line during a writing period in which the first transistor and the third transistor are turned off and the second transistor is turned on It is characterized by comprising.
According to this data line driving circuit, the voltage between the source and the gate of the driving transistor (the first voltage and the second current) while flowing current (first current and second current) from the source to the drain of the driving transistor in the measurement period. Measuring the second voltage) through the third transistor and the signal line to obtain a set of the first current and the first voltage and a set of the second current and the second voltage, and based on these two sets A data signal corresponding to the gradation indicated by the image data can be generated. In this generation, variations in the operating characteristics of the drive transistor are corrected based on the above-described idea. The generated data signal is correctly supplied from the data line to the gate of the driving transistor through the third transistor that is in the ON state in the writing period. Therefore, according to the data line driving circuit, the same effect as that obtained by the second light emitting device can be obtained.

<A: Light-emitting device D>
FIG. 1 is a block diagram showing a configuration of a light emitting device D according to an embodiment of the present invention. The light emitting device D is a device employed in various display devices as means for displaying an image. The light emitting device D drives a pixel array unit 10 in which a plurality of pixel circuits P are arranged in a plane and each pixel circuit P. The scanning line driving circuit 20 and the data line driving circuit 30 to be used, and a voltage generation circuit (not shown) for generating each voltage used in the light emitting device D. Note that the scanning line driving circuit 20, the data line driving circuit 30, and the voltage generation circuit may be configured so that part or all of them forms a single circuit. Further, the scanning line driving circuit 20 (or the data line driving circuit 30 or the voltage generation circuit) may be mounted on the light emitting device D in a manner divided into a plurality of IC chips.

  As shown in FIG. 1, the pixel array unit 10 includes m control lines 12 extending in the X direction, n signal lines 13 extending in the Y direction orthogonal to the X direction, and each signal. A pair of lines 13 and n feeder lines 14 extending in the Y direction are formed (m and n are natural numbers). Each pixel circuit P is disposed at a position corresponding to the intersection of the control line 12 and the pair of the signal line 13 and the power supply line 14. Therefore, these pixel circuits PA are arranged in a matrix of m rows × n columns.

  A voltage generation circuit (not shown) generates a higher potential (hereinafter referred to as “power supply potential”) Vel and a lower potential (hereinafter referred to as “ground potential”) Gnd of the power supply. The power supply potential Vel is output in common to all the power supply lines 14 and supplied to each pixel circuit P.

  The scanning line driving circuit 20 is a circuit for selecting a plurality of pixel circuits P in units of rows for each horizontal scanning period, and outputs a signal corresponding to a signal S1 supplied from a control circuit (not shown) to the control line 12. The pixel circuits P for one row (n) are sequentially selected for each horizontal scanning period. The contents of signals output from the scanning line driving circuit 20 will be described later. The control circuit is a circuit that inputs image data indicating gradation and controls the light emission of the pixel circuit P. Signals S1 and S2 corresponding to the input image data are sent to the scanning line driving circuit 20 and the data line driving circuit 30. To supply.

  The data line driving circuit 30 outputs a signal corresponding to the signal S2 supplied from the control circuit to the signal line 13. The signal S2 includes image data indicating a gradation, and the data line driving circuit 30 outputs a data signal (described later) corresponding to each of one row (n) of pixel circuits P in the horizontal scanning period. Data signals Vdata [1] to Vdata [n]) are generated and output to the signal lines 13. The data signal output to the signal line 13 in the j-th column (j is an integer satisfying 1 ≦ j ≦ n) in the horizontal scanning period in which the i-th row (i is an integer satisfying 1 ≦ i ≦ m) is selected. The potential becomes a level corresponding to the gradation specified for the pixel circuit P located in the i-th row and the j-th column.

  As will be described in detail later, the pixel circuit P includes a light emitting element 11 and a driving transistor Tdr, and the data line driving circuit 30 measures the potential Vg of the gate of the driving transistor Tdr to estimate the operating characteristics of the driving transistor Tdr. A data signal is generated by performing correction based on the estimation result, and this data signal is supplied to the gate of the drive transistor Tdr via the signal line 13. The light-emitting device D includes a light-emitting device DA that performs the above-described measurement and the above-mentioned supply using the same wiring, and a light-emitting device DB that performs the above-described measurement and wiring.

<B: Light emitting device DA>
<B-1: Configuration>
The light emitting device DA includes a pixel circuit PA as the pixel circuit P, a data line 131 as the signal line 13, a scanning line driving circuit 20A as the scanning line driving circuit 20, and a data line driving circuit 30A as the data line driving circuit 30.

  FIG. 2 is a block diagram illustrating a configuration of the pixel circuit PA. In this figure, only one pixel circuit PA located in the i-th row and j-th column is shown, but the other pixel circuits PA have the same configuration. As shown in the figure, the pixel circuit PA includes a light emitting element 11 interposed between a power supply line 14 supplied with a power supply potential Vel and a ground line supplied with a ground potential Gnd. The light-emitting element 11 is a current-driven light-emitting element that emits light with luminance according to the drive current Iel supplied thereto. Typically, a light-emitting layer made of an organic EL (Electro Luminescent) material is used as an anode and a cathode. An OLED (Organic Light Emitting Diode) element interposed between the two.

  As shown in FIG. 2, the control line 12 shown as one wiring for convenience in FIG. 1 actually has three wirings (scanning line 121, measurement control line 122, and light emission control line 123). Including. Each wiring is supplied with a predetermined signal from the scanning line driving circuit 20A. For example, a scanning signal GWRT [i] for selecting the pixel circuit PA in the same row is supplied to the i-th scanning line 121. The measurement control line 122 is supplied with a measurement control signal GMSR [i] for controlling the measurement of the potential Vg. Further, the light emission control line 123 is supplied with a light emission control signal GELA [i] that defines a period during which the light emitting element 11 actually emits light. Specific waveforms of the signals and the operation of the pixel circuit PA corresponding to the waveforms will be described later.

  As shown in FIG. 2, a p-channel type drive transistor Tdr and an n-channel type light emission control transistor Tel are inserted in a path from the feeder 14 to the anode of the light emitting element 11. The drive transistor Tdr is a transistor (actually a thin film transistor) for generating a drive current Iel corresponding to the voltage Vgs between the source and the gate. The source is connected to the power supply line 14 and the drain is a light emission control transistor. Connected to the drain of Tel. The light emission control transistor Tel is a transistor for defining a period during which the drive current Iel is actually supplied to the light emitting element 11, and the source is connected to the anode of the light emitting element 11 and the gate is connected to the light emission control line 123. Is done. Therefore, during the period in which the light emission control signal GELA [i] is maintained at the low level, the light emission control transistor Tel is turned off and the supply of the drive current Iel to the light emitting element 11 is cut off, while the light emission control signal GELA [i] When the signal transitions to the high level, the light emission control transistor Tel is turned on, and the drive current Iel is supplied to the light emitting element 11. The light emission control transistor Tel may be interposed between the drive transistor Tdr and the power supply line 14.

  An n-channel transistor Tb is interposed between the gate and drain of the driving transistor Tdr. The gate of the transistor Tb is connected to the measurement control line 122. Therefore, when the measurement control signal GMSR [i] transitions to a high level, the transistor Tb is turned on and the drive transistor Tdr is diode-connected, and when the measurement control signal GMSR [i] transitions to a low level, the transistor Tb is turned off. Thus, the diode connection of the driving transistor Tdr is released.

The capacitive element C1 shown in FIG. 2 is a capacitor that holds a voltage between the first electrode L1 and the second electrode L2. The first electrode L1 is connected to the source of the driving transistor Tdr, and the second electrode L2 is connected to the gate of the driving transistor Tdr. That is, the voltage Vgs is held in the capacitive element C1. An n-channel transistor Ta is interposed between the second electrode L2 of the capacitive element C1 and the data line 131. The transistor Ta is a switching element that switches between conduction and non-conduction between the second electrode L 2 and the data line 131, and its gate is connected to the scanning line 121. Therefore, in a period in which the scanning signal GWRT [i] is maintained at the low level, the transistor Ta is turned off and the second electrode L2 and the data line 131 are turned off, while the scanning signal GWRT [i] is at the high level. When the transition is made, the transistor Ta is turned on, and the second electrode L2 and the data line 131 are short-circuited.
Since the drive current Iel is thus determined by the gate potential Vg of the drive transistor Tdr, the drive signal Iel is supplied by the data signal Vdata [j] supplied via the data line 131 when the transistor Ta is turned on. The size is determined.

  FIG. 3 is a block diagram showing a configuration of the data line driving circuit 30A. As shown in this figure, the data line driving circuit 30A includes an I / F (interface) block 31A, a plurality of data voltage output blocks 37A, a measurement switching line 32, a current switching line 33, and a scanning circuit block 36. The I / F block 31A receives the signal S2 from the control circuit and supplies the image data VDATA included in the signal S2 to the scanning circuit block 36 in order. When the scanning circuit block 36 includes a shift register and receives supply of image data VDATA for one row, the scanning circuit block 36 converts the image data VD for n columns included in the image data VDATA into n data voltage output blocks 37A. Supply to each. In this supply, the image data VD [j] in the j-th column is passed to the voltage output block 37A in the i-th column.

  The measurement switching line 32 and the current switching line 33 are common to the plurality of data voltage output blocks 37A. The data voltage output block 37A measures the variation in the operating characteristics of the drive transistor Tdr each time before the voltage corresponding to the image data VD [j] is held in the capacitive element C1, and the I / F block 31A A measurement switching signal S7 for instructing the above-described measurement period (a measurement period PMSR described later) is output to the measurement switching line 32. The data voltage output block 37A performs the above-described measurement using two types of constant currents, and the I / F block 31A outputs a current designation signal S6 having a measurement period PMSR as one cycle to the current designation line 33. To do. The I / F block 31A and the scanning circuit block 36 are supplied with the image data VD [j] to each of the plurality of data voltage output blocks 37A in the horizontal scanning period of the i-th row, and in the horizontal scanning period. The head is configured to be the measurement period PMSR.

  FIG. 4 is a block diagram showing a configuration of the data voltage output block 37A. As shown in this figure, the data voltage output block 37A includes an output voltage generation circuit 371, a switch 372, a constant current source 373, a voltage sample hold circuit 374, and a reference voltage generation circuit 375. The output voltage generation circuit 371 generates a data signal Vdata [j] corresponding to the image data VD [j], and outputs it to the end point P1 of the switch 372. The switch 372 conducts the end point P1 or the end point P2 to the data line 131, and switches the end point to be conducted to the data line 131 according to the measurement switching signal S7.

  As shown in FIG. 4, the current designation line 33 shown as one wiring for the sake of convenience in FIG. 3 actually includes two wirings, and the constant current source 373 includes I1 from one wiring. The designation signal S6-1 is supplied, and the I2 designation signal S6-2 is supplied from the other wiring. The constant current source 373 generates a constant current I1 during the period designated by the I1 designation signal S6-1 and generates a constant current I2 during the period designated by the I2 designation signal S6-1, and supplies the constant current I2 to the end point P2. These periods are exclusively assigned to the measurement period PMSR. In the measurement period PMSR, the gate and drain of the drive transistor Tdr are short-circuited. Therefore, in the measurement period PMSR, the drive transistor Tdr is in a diode-connected state, and constant currents I1 and I2 flow between the source and gate.

  The voltage sample and hold circuit 374 can hold two potentials, and during the period designated by the I1 designation signal S6-1, the potential Vref [j] at the end point P2 (the potential of the data line 131) is constant. The last sampled potential is held as the measurement potential V1, and during the period specified by the I2 designation signal S6-2, the potential Vref [j] at the end point P2 is repeatedly sampled at a constant period, The last sampled potential is held as the measurement potential V2. That is, a set of current and potential such as (I1, V1) and (I2, V2) can be measured. Since the drive transistor Tdr exhibits a square characteristic in the saturation region, its operation characteristic can be specified if two pairs of current and potential are known. In the present embodiment, by measuring (I1, V1) and (I2, V2), the operating characteristics of the drive transistor Tdr are specified, and the variation is corrected.

  As described above, the magnitude of the drive current Iel is determined by the data signal Vdata [j]. The data signal Vdata [j] has a potential corresponding to the minimum light amount (black level) to the maximum light amount (white level). The maximum light amount is determined by the specification of the light emitting device DA, and the light emitting element 11 is turned off at the minimum light amount. In the present embodiment, the data signal Vdata [j] corresponding to the minimum light quantity is set so that the gate-source voltage Vgs of the drive transistor Tdr becomes the threshold voltage Vth. In the following description, the potential of the data signal Vdata [j] corresponding to the minimum light amount is referred to as Vb, and the potential of the data signal Vdata [j] corresponding to the maximum light amount is referred to as Vw.

In the present embodiment, the level of the constant current I1 generated by the constant current source 373 is Iw. Iw is equal to the level of the maximum drive current. The maximum drive current is the drive current Iel when the light emitting element 11 emits light with the maximum light amount determined from the specification of the light emitting device DA when the light emitting device DA is manufactured as designed. The level of the constant current I2 is Im, which is given by the equation (1).
Im = Iw / 4 …… (1)
In the present embodiment, the level of the measurement potential V1 in the voltage sample hold circuit 374 is “Vw”, and the level of the measurement potential V2 is “Vm”. That is, in this embodiment, a set of (Iw, Vw) and (Iw / 4, Vm) is measured.

  The reason why Im = Iw / 4 is set is that Vb can be easily obtained from Vw and Vm. This point will be described with reference to FIG. As shown in FIG. 6, the characteristic line indicating the characteristic of the square root of the drive current Iel with respect to the potential Vg of the drive transistor Tdr of the pixel circuit P shows a temperature change, deterioration, etc. even if there is an individual difference in the operation characteristics of the drive transistor Tdr. Even if there is a dynamic variation due to these factors, it will be linear. Therefore, if two or more sets of the potential Vg and the drive current Iel can be obtained, the potential Vb corresponding to the threshold voltage Vth of the drive transistor Tdr can be estimated by a simple calculation such as multiplication or subtraction of a constant multiple. it can. The fact that it can be estimated by a simple calculation is also derived from mathematical formulas as described below.

As described above, the drive transistor Tdr exhibits a square characteristic in the saturation region. In other words, the operating characteristic model of the driving transistor expressed by the equation (2) is not destroyed in any state. In Expression (2), “β” is a gain coefficient of the driving transistor Tdr.
Iel = (β / 2) · (Vgs−Vth) ² (2)
Therefore, Expression (3) is obtained for the constant current I1, and Expression (4) is obtained for the constant current I2.
Iw = (β / 2) · ((Vel−Vw) − (Vel−Vb)) ² (3)
Iw / 4 = (β / 2) · ((Vel−Vm) − (Vel−Vb)) ² (4)
Then, by substituting the right side of equation (3) into Iw on the left side of equation (4) and rearranging, equation (5) is obtained.
Vb = 2 ・ Vm−Vw …… (5)
That is, Vb can be easily calculated by subtracting Vw from the value obtained by doubling Vm. In this embodiment, two sets are used for estimation. However, the number of sets may be modified to three or more to improve the accuracy of estimation.

  The reference voltage generation circuit 375 generates and outputs a reference potential V3 having a level Vw and a reference potential V4 having a level Vb based on the measured potentials V1 and V2 held in the voltage sample hold circuit 374. Vw and Vb are estimated values of the gate potential Vg of the drive transistor Tdr, Vw is a level when the drive current Iel becomes the maximum drive current, and Vb is obtained by subtracting the threshold voltage Vth of the drive transistor Tdr from the power supply potential Vel. It is the level obtained. The output voltage generation circuit 375 generates the data signal Vdata [j] based on the reference potential V3 and the reference potential V4 output from the reference voltage generation circuit 375.

  Specifically, as shown in FIG. 5, the reference voltage generation circuit 375 includes an operational amplifier A and resistance elements R1 and R2. The measurement potential V2 is input to the non-inverting input terminal of the operational amplifier A, the measurement potential V1 is input to the inverting input terminal via the resistor element R1, and the output terminal serving as the reference potential V4 is inverted via the resistor element R2. Connected to the end. In the present embodiment, the resistance value of the resistance element R1 and the resistance value of the resistance element R2 are the same, but it is also possible to adopt a mode in which they are not the same.

  The configuration of the output voltage generation circuit 371 will be described with reference to FIG. As shown in FIG. 7, in this embodiment, the output voltage generation circuit 371 includes a ladder circuit RR and a selection circuit 3711. This is merely an example, and, for example, a device including a general D / A converter (digital / analog converter) may be employed as the output voltage generation circuit 371.

  The ladder circuit RR is configured by connecting q resistance elements RR1 to RRq in series between a wiring 3712 having a reference potential V3 and a wiring 3713 having a reference potential V4. The wiring 3712, the wiring 3713, and the q−1 connecting points of the resistance elements RR1 to RRq are connected to the selection circuit 3711, respectively. That is, the selection circuit 3711 is supplied with a potential having a level corresponding to each of all gradations that can be represented by the image data. The selection circuit 3711 selects a potential having a level corresponding to the supplied image data VD [j] from the applied potential, and outputs a data signal Vdata [j] having the selected potential. Note that q is a natural number obtained by subtracting 1 from the number of gradations that the image data can indicate.

  Resistance values of the resistance elements RR1 to RRq are individually determined. Specifically, when the potential level of the wiring 3712 is set as the upper limit and the potential level of the wiring 3713 is set as the lower limit, a potential of a level that appropriately divides the level range determined by the upper limit and the lower limit is given to the selection circuit 3711. To be determined. Here, “appropriately dividing” means that the potential selected according to the image data by the output voltage generation circuit 371 divides so as to emit light with a light amount corresponding to the gradation indicated by the image data. To do.

  The configuration of the output voltage generation circuit 371 is not limited to that described above. For example, the configuration shown in FIG. According to this configuration, the circuit scale can be reduced. In this configuration, the division of the level range determined by the upper limit and the lower limit is limited to equal division. However, since the thin film transistor has a substantially square characteristic, it is sufficiently practical.

  FIG. 9 is a timing chart showing specific waveforms of signals generated by the scanning line driving circuit 20A and the data line driving circuit 30A. As shown in this figure, the scanning signals GWRT [1] to GWRT [m] are sequentially set to the high level every horizontal scanning period (1H). That is, the scanning signal GWRT [i] maintains a high level in the i-th horizontal scanning period of the vertical scanning period (1V) and maintains a low level in other periods. The transition of the scanning signal GWRT [i] to the high level means selection of each pixel circuit PA in the i-th row. FIG. 9 illustrates the case where the falling edge of the scanning signal GWRT [i] and the rising edge of the scanning signal GWRT [i + 1] of the next row are simultaneous, but the scanning signal GWRT [i] The scanning signal GWRT [i + 1] may rise at a timing when a predetermined time has passed since the falling.

  As shown in FIG. 9, the period during which the scanning signal GWRT [i] is at the high level coincides with the period in which the writing period PWRT [i] is continued after the measurement period PMSR [i]. The measurement period PMSR [i] is a period for measuring variations in the operating characteristics of the drive transistor Tdr, and the write period PWRT [i] writes a voltage corresponding to the gradation indicated by the image data to the capacitive element C1. It is a period for. The measurement control signal GMSR [i] is a signal that becomes high level in the measurement period PMSR [i] and maintains low level in other periods. The measurement switching signal S7 is a signal that is maintained at a high level during the measurement period PMSR [i] and is maintained at a low level during the writing period PWRT [i].

  The measurement period PMSR [i] is divided into a first half I1 period PI1 [i] and a second half I2 period PI2 [i]. The I1 period PI1 [i] is a period in which the constant current source 373 generates the constant current I1, and the I2 period PI2 [i] is a period in which the constant current source 373 generates the constant current I2. The I1 designation signal S6-1 is a signal that is maintained at a high level during the I1 period PI1 [i], and is maintained at a low level during the I2 period PI2 [i] and the writing period PWRT [i]. The I2 designation signal S6-2 is a signal that is maintained at a high level during the I2 period PI2 [i], and is maintained at a low level during the I1 period PI1 [i] and the writing period PWRT [i]. The light emission control signal GELA [i] is a period from the lapse of the writing period PWRT [i] to the start of the measurement period PMSR [i] when the measurement control signal GMSR [i] is at a high level (that is, the light emission period PE). [i]) becomes a high level and becomes a low level in other periods (that is, a period in which the scanning signal GWRT [i] is at a high level).

<B-2: Operation>
Next, a specific operation of the pixel circuit PA will be described with reference to FIGS. Hereinafter, the operation of the pixel circuit PA in the j-th column belonging to the i-th row is divided into the measurement period PMSR [i], the writing period PWRT [i], and the light emission period PE [i], and the measurement period PMSR [i ] Will be described by dividing into an I1 period PI1 [i] and an I2 period PI2 [i].

(A) Measurement period PMSR [i]
In the measurement period PMSR [i], as shown in FIG. 9, the scanning signal GWRT [i] and the measurement control signal GMSR [i] maintain a high level and the light emission control signal GELA [i] maintains a low level. To do. Therefore, as shown in FIGS. 10 and 11, the transistors Ta and Tb are turned on, and the light emission control transistor Tel is kept off. In this state, the drive transistor Tdr is diode-connected, and the gate of the drive transistor Tdr and the data line 131 are conducted via the transistor Ta. In the measurement period PMSR [i], the measurement switching signal S7 is maintained at a low level. Therefore, the switch 372 in FIG. 4 is switched to the end point P2 side, and the end point P2 is connected to the data line 131.

(A-1) I1 period PI1 [i]
In the I1 period PI1 [i], as shown in FIG. 9, the I1 designation signal S6-1 maintains a high level and the I2 designation signal S6-2 maintains a low level. Therefore, as shown in FIG. 10, the constant current source 373 operates so that the constant current I1 flows through the end point P2, and the voltage sample hold circuit 374 repeatedly samples the potential Vref [j] at the end point P2 at a constant period. In the measurement period PMSR [i] including the I1 period PI1 [i], the end point P2 is connected to the data line 131, and the data line 131 is electrically connected to the gate of the drive transistor Tdr through the transistor Ta. Since the diode is connected, the current starts from the feeder line 14 and passes through the source of the drive transistor Tdr, the drain of the drive transistor Tdr, the transistor Tb, the transistor Ta, the data line 131, and the end point P2 (hereinafter referred to as “measurement”). At the start of the I1 period PI1 [i], charge is stored in the parasitic capacitance of the capacitive element C1 and the data line 131, so that the flow path of the current flowing through the end point P2 becomes the measurement path. Although not limited, when a certain amount of time has passed, the light path is limited to the measurement path.In the light emitting device DA, the flow path of the current flowing through the end point P2 is limited to the measurement path. I1 period PI1 [i] and the sample repetition period by the voltage sample hold circuit 374 are determined so that the potential Vref [j] can be reliably sampled. ], The potential Vref [j] sampled last by the voltage sample and hold circuit 374, that is, the measured potential V1, can be regarded as the potential Vg when the drive current Iel is a constant current I1. This is why the level can be regarded as a potential of Vw.

(A-2) I2 period PI2 [i]
In the I2 period PI2 [i], as shown in FIG. 9, the I2 designation signal S6-2 maintains a high level and the I1 designation signal S6-1 maintains a low level. Therefore, as shown in FIG. 11, the constant current source 373 operates so that the constant current I2 flows through the end point P2, and the voltage sample hold circuit 374 repeatedly samples the potential Vref [j] at the end point P2 at a constant period. The current flow path in the I2 period PI2 [i] is the same as the current flow path in the I1 period PI1 [i], and after a certain amount of time has passed, it is limited to the measurement path only. In the light emitting device DA, the I2 period PI2 [i] and the voltage sample / hold circuit are provided so that the potential Vref [j] when the flow path of the current flowing through the end point P2 is limited to the measurement path can be reliably sampled. The sample repetition period according to 374 is determined. Therefore, the potential Vref [j] last sampled by the voltage sample hold circuit 374 in the I2 period PI2 [i], that is, the measured potential V2, can be regarded as the potential Vg when the drive current Iel is the constant current I2. .

  At the end of the measurement period PMSR [i], the voltage sample hold circuit 374 in FIG. 4 holds the measurement potential V1 having the level Vw and the measurement potential V2 having the level Vm. Therefore, at this time, the reference potentials V3 and V4 generated by the reference voltage generation circuit 375 are based on the measurement potential V1 whose level is Vw and the measurement potential V2 whose level is Vm, and the output voltage generation circuit 371. The potentials of the wirings 3712 and 3713 (see FIG. 7) are also set.

  In the present embodiment, since the level (Im) of the constant current I2 is 1/4 of the level (Iw) of the constant current I1, the flow path of the current flowing through the end point P2 after the constant current I2 starts flowing is the measurement path. The time until the current is limited to is usually longer than the time from when the constant current I1 starts to flow until the current flow path flowing through the end point P2 is limited to the measurement path. Therefore, in the present embodiment, both periods are determined such that the I2 period PI2 [i] is longer than the I1 period PI1 [i]. In this embodiment, a constant current I1 having a large absolute value is caused to flow prior to a constant current I2 having a small absolute value. However, this is done at the start of the measurement period PMSR [i]. If the amount of charge remaining in the capacitive element C1 is not constant and a constant current I2 having a small absolute value is first flowed, before the charge is completely flowed, that is, before the current flow path is limited to the measurement path. This is because the I2 period PI2 [i] may end.

(B) Write period PWRT [i]
In the writing period PWRT [i], as shown in FIG. 9, the scanning signal GWRT [i] maintains a high level, and the light emission control signal GELA [i] and the measurement control signal GMSR [i] are at a low level. maintain. Accordingly, as shown in FIG. 12, the transistor Tb transitions to the off state, the transistor Ta maintains the on state, and the light emission control transistor Tel maintains the off state. In this state, the diode connection of the drive transistor Tdr is released. In the writing period PWRT [i], the measurement switching signal S7 is maintained at a high level. Therefore, the switch 372 in FIG. 4 is switched to the end point P1 side, and the end point P1 is connected to the data line 131. Therefore, the potential Vg of the gate of the driving transistor Tdr becomes the potential of the data signal Vdata [j], and the voltage Vgs = Vel−Vdata [j] is written in the capacitive element C1.

  As apparent from FIGS. 5 to 9, in the writing period PWRT [i], the potential of the wiring 3712 of the output generation circuit 371 is sampled and held in the voltage sample hold circuit 374 in the immediately preceding I1 period PI1 [i]. The reference potential V3 based on the measured potential V1 is maintained, and the potential of the wiring 3713 is based on the measured potentials V1 and V2 sampled and held in the voltage sample hold circuit 374 in the immediately preceding measurement period PMSR [i]. The reference potential V4 is maintained. Therefore, the data signal Vdata [j] output from the output generation circuit 371 in the writing period PWRT [i] has a level corresponding to the image data VD [j] and is estimated in the immediately preceding measurement period PMSR [i]. Is maintained at a level selected from a range having Vw and Vb as upper and lower limits, that is, a level corresponding to the operating characteristics of the drive transistor Tdr in the immediately preceding measurement period PMSR [i]. Accordingly, the level of the voltage Vgs written to the capacitive element C1 in the writing period PWRT [i] is the light emitting element 11 with a light amount corresponding to the gradation indicated by the image data VD [1] regardless of the operating characteristics of the driving transistor Tdr. The drive current Iel at a level for emitting light is supplied to the light emitting element 11 from the drive transistor Tdr.

(C) Light emission period PE [i]
In the light emission period PE [i], as shown in FIG. 9, the scanning signal GWRT [i] and the measurement control signal GMSR [i] maintain a low level and the light emission control signal GELA [i] maintains a high level. To do. Therefore, as shown in FIG. 13, the transistor Ta changes to the off state, the transistor Tb maintains the off state, and the light emission control transistor Tel changes to the on state. In this state, the capacitive element C1 holds the voltage Vgs written in the immediately preceding write period PWRT [i], and the drive current Iel corresponding to the voltage Vgs is supplied from the power supply line to the drive transistor Tdr and the light emission control transistor Tel. Then, the light is supplied to the light emitting element 11. By supplying the drive current Iel, the light emitting element 11 responds to the amount of light corresponding to the voltage Vgs held in the capacitive element C1, that is, the gradation indicated by the image data VD [1], that is, the gradation indicated by the image data. Emits light with a high light intensity.

  According to the light-emitting device DA described above, the potential Vg of the gate of the drive transistor Tdr is measured while a constant current flows from the source to the drain of the drive transistor Tdr. Accurate measurement can be performed without the influence of capacity. Therefore, the light emitting element 11 can be caused to emit light with a light amount accurately corresponding to the gradation indicated by the image data. In addition, the data line 131 can be used to flow a constant current from the source to the drain of the drive transistor Tdr and to measure the potential Vg of the gate of the drive transistor Tdr. Therefore, a general pixel circuit can be used.

  In the light emitting device DA, the measurement of the gate potential Vg of the driving transistor Tdr, the estimation of the operating characteristics of the driving transistor Tdr, and the correction of the data signal Vdata [j] based on the estimation are performed by a RAM (Random Access Memory) or the like. A simple configuration (voltage sample and hold circuit 374, reference voltage generation circuit 375, and output voltage generation circuit 376) that does not require a memory is performed quickly. Therefore, before the light emitting element 11 emits light, the above measurement, estimation, and correction can be performed on the driving transistor Tdr that supplies the driving current Iel to the light emitting element 11. Therefore, not only the static variation such as the variation in individual operation characteristics of the drive transistor Tdr but also the dynamic variation due to factors such as temperature change and deterioration can be corrected appropriately.

<C: Modification of Pixel Circuit PA>
The configuration of the pixel circuit PA is not limited to that shown in FIG. For example, the configuration shown in FIGS.
In the configuration shown in FIG. 14, a p-channel transistor is used as the light emission control transistor Tel, and a scanning line 121 is connected to the gate of the light emission control transistor Tel. If this configuration is adopted, the light emission control line 123 is not necessary.
In the configuration shown in FIG. 15, the scanning line 121 is connected to the gate of the transistor Tb. According to this configuration, in the writing period PWRT [i], the transistor Tb is turned on and the gate and the drain of the driving transistor Tdr are conducted, but the light emission control transistor Tel is turned off. Even when a voltage is written, the light emitting element 11 does not emit light. If this configuration is adopted, the measurement control line 122 is unnecessary.
The configuration shown in FIG. 16 is obtained by combining the configuration shown in FIG. 14 and the configuration shown in FIG. If this configuration is adopted, the measurement control line 122 and the light emission control line 123 are unnecessary.
The configuration shown in FIG. 17 is different from the configuration shown in FIG. 15 in that the drain of the drive transistor Tdr and the data line 131 are replaced with the transistor Ta that switches conduction / non-conduction between the gate of the drive transistor Tdr and the data line 131. It is a point provided with transistor Tc which switches conduction / non-conduction. If this configuration is adopted, the measurement control line 122 is unnecessary.
The configuration shown in FIG. 18 is different from the configuration shown in FIG. 17 in that a p-channel transistor is used as the light emission control transistor Tel, and the scanning line 121 is connected to the gate of the light emission control transistor Tel. If this configuration is adopted, the measurement control line 122 and the light emission control line 123 are unnecessary.
In the configuration shown in FIG. 19, a p-channel transistor is used as the light emission control transistor Tel, and the measurement control line 122 is connected to the gate of the light emission control transistor Tel. According to this configuration, in the writing period PWRT [i], the light emission control transistor Tel is turned on, and the light emitting element 11 emits light with a light amount corresponding to the voltage written to the capacitive element C1. That is, the writing period PWRT [i] and the light emission period PE [i] overlap. If this configuration is adopted, the light emission control line 123 is not necessary.
In the configuration shown in FIG. 20, the transistor Ta is interposed between the gate of the driving transistor Tdr and the data line 131, and the transistor Tc is interposed between the drain of the driving transistor Tdr and the data line 131. In the measurement period PMSR [i], the transistor Ta and the transistor Tc are turned on, and the gate and the drain of the drive transistor Tdr are conducted through the data line 131. Therefore, the current of the driving transistor Tdr programmed with the data voltage can be read out to the data line. Since it is easy to connect an inspection circuit for inspecting circuit operation to the data line, according to this configuration, it is possible to easily inspect circuit operation.
The configuration of the pixel circuit PA may be a configuration in which the conductivity type of each transistor is inverted in the various pixel circuits described above.

<D: Light emitting device DB>
The light emitting device DB includes a pixel circuit PB as the pixel circuit P, a data line 131 and a signal line 132 as the signal line 13, a scanning line driving circuit 20B as the scanning line driving circuit 20, and a data line driving circuit as the data line driving circuit 30. 30B. Signals output from the scanning line driving circuit 20B and the data line driving circuit 30B will be described later.

  FIG. 21 is a circuit diagram showing a configuration of the pixel circuit PB. In this figure, only one pixel circuit PB located in the i-th row and j-th column is shown, but the other pixel circuits PB have the same configuration. As shown in FIG. 21, the control line 12 shown as one wiring for convenience in FIG. 1 is actually four wirings (scanning line 121, measurement control line 122, light emission control line 123, measurement). Selection line 124). Further, as shown in FIG. 21, the signal line 13 illustrated as one wiring for convenience in FIG. 1 actually includes two wirings (data line 131 and signal line 132). As shown in FIG. 21, a part of the configuration of the pixel circuit PB is the same as the configuration shown in FIG. The pixel circuit PB is different from the pixel circuit A in that an n-channel transistor Td is interposed between the gate of the driving transistor Tdr and the signal line 132, and the gate of the transistor Td is connected to the measurement selection line 124. It is a point.

  A predetermined signal is supplied to the measurement selection line 124 from the scanning line driving circuit 20B. For example, the measurement selection signal GMSR1 [i] for selecting the pixel circuit PB in the same row for measurement is supplied to the measurement selection line 124 in the i-th row. In addition, a measurement control signal GMSR2 [i] is supplied to the measurement control line 122 in the i-th row instead of the measurement control signal GMSR [i]. Further, the light emission control signal GELB is supplied to the i-th row of the i-th row in place of the light emission control signal GELA. Specific waveforms of each signal will be described later. The signal line 132 is a wiring for measuring the potential of the gate of the driving transistor Tdr. For example, in the measurement for the pixel circuit PB in the j-th column, the potential Vref of the signal line 132 in the j-th column is a direct measurement target. Since the signal line 132 exists, the role of the data line 131 is limited to supply of a data signal.

  FIG. 22 is a block diagram showing a configuration of the data line driving circuit 30B. As shown in this figure, the data line driving circuit 30B includes an I / F block 31B, a plurality of data voltage output blocks 37B, a current switching line 33, and a scanning circuit block 36, and does not include the measurement switching line 32. The I / F block 31B measures the variation in the operating characteristics of the drive transistor Tdr every time before holding the voltage according to the image data VD [j] in the capacitive element C1, and the constant currents I1 and I2 are measured. To perform the above measurements. The I / F block 31B is different from the I / F block 31A in that the measurement switching signal S7 is not output, and the current specifying signal S7 is output to the current switching line 33 instead of the current specifying signal S6.

  FIG. 23 is a diagram showing a configuration of the data voltage output block 37B. As shown in this figure, the data voltage output block 37B includes an output voltage generation circuit 371, a constant current source 373, a voltage sample hold circuit 374, and a reference voltage generation circuit 375, and does not include a switch 372. The output destination of the data signal Vdata [j] from the output voltage generation circuit 371 is the data line 131, and the constant current source 373 and the voltage sample hold circuit 374 are connected to the signal line 132.

  As shown in FIG. 23, the current designating line 33 shown as one wiring for convenience in FIG. 22 actually includes two wirings, and the constant current source 373 has I1 from one wiring. The designation signal S8-1 is supplied, and the I2 designation signal S8-2 is supplied from the other wiring. The constant current source 373 generates a constant current I1 during the period specified by the I1 specifying signal S8-1 and generates a constant current I2 during the period specified by the I2 specifying signal S8-1, and supplies the constant current I2 to the signal line 132. Although mentioned later in detail, both periods do not overlap. The voltage sample and hold circuit 374 can hold two potentials, and repeatedly samples the potential Vref [j] of the signal line 132 at a constant period during the period designated by the I1 designation signal S8-1. The sampled potential is held as the measured potential V1, and during the period designated by the I2 designation signal S8-2, the potential Vref [j] of the signal line 132 is repeatedly sampled at a constant cycle, and the last sampled potential is sampled. Is held as the measurement potential V2.

  FIG. 24 is a timing chart showing specific waveforms of signals generated by the scanning line driving circuit 20B and the data line driving circuit 30B. As shown in this figure, the measurement selection signal GMSR1 [i] and the measurement control signal GMSR2 [i] are maintained at the high level in the (i-1) -th horizontal scanning period in the vertical scanning period (1V). The low level is maintained during other periods. The transition of the measurement control signal GMSR2 [i] to the high level means the start of measurement for each pixel circuit PA in the i-th row, and the transition to the low level means the end of the measurement. Therefore, in the light emitting device DB, the period during which the measurement selection signal GMSR1 [i] and the measurement control signal GMSR2 [i] are at the high level is the measurement period PMSR [i]. Accordingly, the entire period in which the scanning signal GWRT [i] is at the high level is the writing period PWRT [i], and the measurement period PMSR [i] and the writing period PWRT [i-1] coincide. FIG. 24 illustrates the case where the falling edge of the measurement selection signal GMSR1 [i] and the rising edge of the measurement selection signal GMSR1 [i + 1] of the next row are simultaneous, but the measurement selection signal GMSR1 [ The measurement selection signal GMSR1 [i + 1] may rise at a timing when a predetermined time has elapsed from the fall of i]. This also applies to the measurement control signal GMSR2 [i].

  The I1 designation signal S6-1 is a signal that is maintained at a high level during the first half I1 period PI1 [i] of the measurement period PMSR [i] and is maintained at a low level during the second half I2 period PI2 [i]. The I2 designation signal S6-2 is a signal that is maintained at a high level during the I2 period PI2 [i] and is maintained at a low level during the I1 period PI1 [i]. The light emission control signal GELB [i] is measured during the measurement period PMSR [i] (writing in which the measurement selection signal GMSR1 [i] and the measurement control signal GMSR2 [i] become high level after the writing period PWRT [i] has elapsed. It becomes high level in a period before the start of the period PWRT [i-1]) (that is, the light emission period PE [i]), and other periods (that is, the scanning signal GWRT [i], the measurement selection signal GMSR1 [i], or This is a signal that becomes low level during the period when the measurement control signal GMSR2 [i] is high level.

  According to the light emitting device DB described above, in the (i−1) th horizontal scanning period, in the pixel circuit PB in the (i−1) th row, the transistor Ta is turned on and the transistors Tb and Td are turned off. Thus, the voltage can be written into the capacitor C1, and in the pixel circuit PB in the i-th row, the transistor Ta is turned off and the transistors Tb and Td are turned off. It becomes possible to measure the potential Vg (Vref) of the driving transistor Tdr. Since the potential measured in the (i−1) th horizontal scanning period is held in the voltage sample and hold circuit 374, the pixel circuit PB in the jth column of the (i−1) th row in the i th horizontal scanning period. The data signal Vdata [j] given to the gate of the driving transistor Tdr is corrected according to the operating characteristics of the driving transistor Tdr. Therefore, the same effect as the light emitting device DA can be obtained. However, a general pixel circuit cannot be used.

  Even if the potential of the data line is set to the potential of the data signal and the data line and the gate of the driving transistor Tdr are made conductive, the potential of the gate does not immediately become the potential of the data signal. Some time is required. Therefore, from the viewpoint of improving the light emission quality, it is better to secure the writing period as long as possible in the horizontal scanning period. On the other hand, there is a demand for a large screen and high definition in the light emitting device, and the horizontal scanning period is in a direction to be shortened. Therefore, from the viewpoint of improving the light emission quality, the ratio of the writing period in the horizontal scanning period should be increased. On the other hand, according to the light emitting device DB, since the above-described measurement can be performed for the pixel circuit PB in the i-th row in the (i−1) -th horizontal scanning period, the entire horizontal scanning period is written in the writing period. It can be. Therefore, according to the light emitting device DB, the light emission quality can be improved.

<E: Modification of Light Emitting Device DB>
In the light emitting device DB, the measurement for the pixel circuit PB in the i-th row is performed in the (i−1) th horizontal scanning period, but this is modified and performed in the i−2th horizontal scanning period. You may do it. This is merely an example. In short, the horizontal scanning period in which the above measurement is performed may not be the i-th horizontal scanning period.
The light emitting device DB may be modified so that the measurement selection signal GMSR1 [i] is used as the measurement control signal GMSR2 [i]. If this configuration is adopted, the measurement control line 122 is unnecessary.

<F: Modification of Light Emitting Device D>
Various modifications can be made to each of the above embodiments. An example of a specific modification is as follows. In addition, you may combine each following aspect suitably.
The light-emitting device D is configured to estimate the operating characteristics of the drive transistor Tdr based on the measurement potential V1 and the measurement potential V2, but this is modified and three or more potentials are applied using three or more constant currents. It is also possible to measure and to estimate the operating characteristics of the drive transistor Tdr based on these. In this case, the accuracy of estimation, and hence the quality of light emission, is improved.
The light-emitting device D includes a constant current source 373 that can generate constant currents I1 and I2, and is modified to include a first constant current source that generates a constant current I1, and a second constant current I2 that generates a constant current I2. A current source and a selection circuit may be provided. This selection circuit selects the constant current I1 and the constant current I2 in the measurement period, and switches the constant current that flows through the data line 131 or the signal line 132. Further, the first constant current source and the second constant current source may be provided in common for the data voltage output blocks in each row. In this case, a selection circuit may be provided in common for the data voltage output blocks of each row.
The light emitting device D includes a voltage sample / hold circuit 374 capable of holding and outputting two kinds of potentials, but this is modified to sample the potential of the data line 131 or the signal line 132 in the I1 period PI1, The first sample hold circuit that can hold and output the sampled potential as the measurement potential V1 and the potential of the data line 131 or the signal line 132 can be sampled in the I2 period PI2, and the sampled potential can be held and output as the measurement potential V2. A second sample hold circuit may be provided.
In the light emitting device D, the operation characteristics of the drive transistor Tdr are estimated based on the measured potentials V1 and V2, and the data signal Vdata is corrected for all gradations. The data signal Vdata may be corrected only for the gradation. For example, the estimated operation characteristic may be divided into a plurality of gradation ranges, and the data signal Vdata may be corrected for only one range, or the data signal Vdata may be corrected individually for each range. May be. As a specific example of the latter, the first potential, the second potential, and the third potential are measured by flowing three kinds of constant currents, and the data signal indicating the gradation in the first range is set to the first potential and the second potential. For example, a mode in which the correction based on the second potential and the third potential is performed on the data signal indicating the gradation in the second range can be exemplified.
In addition, although the light emitting device D employs an OLED element as the light emitting element 11, it may be modified to employ an inorganic EL element or an LED (Light Emitting Diode) element as the light emitting element 11. The light emitting element 11 is not limited to this, and various light emitting elements that are driven by an electric current and whose light amount changes according to the level of the driving current can be employed.

<G: Application example>
Next, an electronic apparatus using the light emitting device D according to any one of the embodiments described above will be described. FIG. 25 is a perspective view showing a configuration of a mobile personal computer that employs the light emitting device D as a display device. The personal computer 2000 includes a light emitting device D 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 light emitting device D uses an OLED element as the light emitting element 11, it is possible to display an easy-to-see screen with a wide viewing angle.

  FIG. 26 shows a configuration of a mobile phone to which the light emitting device D is applied. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and a light emitting device D as a display device. By operating the scroll button 3002, the screen displayed on the light emitting device D is scrolled.

  FIG. 27 shows a configuration of a personal digital assistant (PDA) to which the light emitting device D is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and a light emitting device D as a display device. When the power switch 4002 is operated, various kinds of information such as an address book and a schedule book are displayed on the light emitting device D.

  Electronic devices to which the light emitting device according to the present invention is applied include those shown in FIGS. 25 to 27, digital still cameras, televisions, video cameras, car navigation devices, pagers, electronic notebooks, electronic papers, calculators. , Word processors, workstations, videophones, POS terminals, printers, scanners, copiers, video players, devices equipped with touch panels, and the like. Further, the use of the light emitting device according to the present invention is not limited to the display of images. For example, in an image forming apparatus such as an optical writing type printer or an electronic copying machine, a writing head that exposes a photosensitive member according to an image to be formed on a recording material such as paper is used. However, the light emitting device of the present invention is used. The unit circuit referred to in the present invention is a concept including not only a pixel circuit constituting a pixel of a display device but also a circuit that becomes a unit of exposure in the image forming apparatus.

It is a figure which shows the structure of the light-emitting device D (light-emitting device DA, DB) which concerns on embodiment of this invention. It is a circuit diagram which shows the structure of pixel circuit PA (pixel circuit P) in light-emitting device DA. It is a figure which shows the structure of 30 A of data line drive circuits in light-emitting device DA. It is a figure which shows the structure of the data voltage output block 37A in light-emitting device DA. It is a circuit diagram showing a configuration of a reference voltage generation circuit 375 in the data voltage output block 37A. It is a figure which shows the characteristic of the square root of the drive current Iel with respect to the electric potential Vg of the gate of the drive transistor Tdr of the pixel circuit P. It is a figure which shows the structure of the output voltage generation circuit 371 in the data voltage output block 37A. 6 is a diagram illustrating another configuration example of the output voltage generation circuit 371. FIG. 4 is a timing chart showing specific waveforms of signals generated by a scanning line driving circuit 20A and a data line driving circuit 30A in the light emitting device DA. FIG. 6 is a diagram for explaining a specific operation of the pixel circuit PA in an I1 period. It is a diagram for explaining a specific operation of the pixel circuit PA in the I2 period. It is a diagram for explaining a specific operation of the pixel circuit PA in the writing period. It is a figure for demonstrating the specific operation | movement of the pixel circuit PA in the light emission period. It is a circuit diagram which shows the modification of pixel circuit PA. It is a circuit diagram which shows the modification of pixel circuit PA. It is a circuit diagram which shows the modification of pixel circuit PA. It is a circuit diagram which shows the modification of pixel circuit PA. It is a circuit diagram which shows the modification of pixel circuit PA. It is a circuit diagram which shows the modification of pixel circuit PA. It is a circuit diagram which shows the modification of pixel circuit PA. It is a circuit diagram which shows the structure of the pixel circuit PB (pixel circuit P) in light-emitting device DB. It is a figure which shows the structure of the data line drive circuit 30B in light-emitting device DB. It is a figure which shows the structure of the data voltage output block 37B in the data line drive circuit 30B. It is a timing chart which shows the specific waveform of each signal which the scanning line drive circuit 20B in the light-emitting device DB and the data line drive circuit 30B generate | occur | produce. It is a perspective view which shows the specific form of the electronic device which concerns on this invention. It is a perspective view which shows the specific form of the electronic device which concerns on this invention. It is a perspective view which shows the specific form of the electronic device which concerns on this invention.

Explanation of symbols

D (DA, DB): Light emitting device, P (PA, PB): Pixel circuit, 11: Light emitting element, 12: Control line, 121: Scan line, 122: Measurement control line, 123: Emission control line 124... Measurement selection line 13... Signal line 131... Data line 132... Signal line 14... Feed line 20 (20A.20B). 30A, 30B) ...... Data line drive circuit, 31A, 31B ... I / F block, 32 ... Measurement switching line, 33 ... Current switching line, 36 ... Scanning circuit block, 37A, 37B ... Data voltage output Block, 371 ... Output voltage generation circuit, 372 ... Switch, 373 ... Constant current source (first current source, second current source and selection circuit), 374 ... Voltage sample hold circuit (first sample hold circuit and 2nd Sun Ruhorudo circuit), 375 ...... reference voltage generating circuit, Tdr ...... driving transistor, Tel ...... emission control transistor, Ta, Tb, Tc, Td ...... transistor.

Claims (12)

A data signal that determines the level of the drive current is supplied to a unit circuit that includes a light emitting element that emits light with a light amount corresponding to the level of the drive current, and a drive transistor that supplies the drive current to the light emitting element. A unit circuit driving method for controlling the light amount of the light emitting element using the data signal corresponding to image data indicating:
With the gate and drain of the driving transistor electrically connected, the first current is passed from the source to the drain of the driving transistor, and the voltage between the source and gate of the driving transistor is measured as the first voltage. And
The voltage between the source and gate of the driving transistor is measured as the second voltage while a second current is passed from the source to the drain of the driving transistor in a state where the gate and drain of the driving transistor are electrically connected. And
The operation of the driving transistor based on the set of the first current and the first voltage and the set of the second current and the second voltage so that the light amount of the light emitting element becomes a gradation indicated by the image data. Correcting the variation in characteristics to generate the data signal corresponding to the gradation indicated by the image data;
Supplying the data signal to the gate of the driving transistor;
A driving method of a unit circuit. In the step of converting the image data into the data signal,
Based on the set of the first current and the first voltage and the set of the second current and the second voltage, the voltage of the data signal corresponding to the maximum gradation of the image data and the minimum rank of the image data Generating a voltage of the data signal corresponding to the key;
Based on the generated voltage, the variation in the operating characteristics of the driving transistor is corrected to generate the data signal corresponding to the gradation indicated by the image data.
The unit circuit driving method according to claim 1, wherein: A light-emitting element that emits light with a light amount corresponding to a level of the drive current; a drive transistor that supplies the drive current to the light-emitting element; a first transistor provided between a gate and a drain of the drive transistor; and the drive A unit circuit including a second transistor provided between a gate or drain of a transistor and a data line is supplied with a data signal for determining a level of the driving current through the data line every predetermined period, so that a gradation is obtained. A unit circuit driving method for controlling the light amount of the light emitting element using the data signal corresponding to image data to be displayed,
In the predetermined period,
In the measurement period in which the first transistor and the second transistor are in the ON state, the first current is supplied from the source to the drain of the driving transistor, and the voltage of the data line is set between the source and the gate of the driving transistor. Is measured as the first voltage,
Measuring the voltage of the data line as the second voltage between the source and the gate of the driving transistor while passing a second current from the source to the drain of the driving transistor in the measurement period;
The operation of the driving transistor based on the set of the first current and the first voltage and the set of the second current and the second voltage so that the light amount of the light emitting element becomes a gradation indicated by the image data. The data signal corresponding to the gradation indicated by the image data is generated by correcting characteristic variation, and the data signal is output during a writing period in which the first transistor is turned off and the second transistor is turned on. Supplying the gate of the driving transistor by supplying to the data line;
A driving method of a unit circuit. A driving method of a light emitting device according to the present invention corresponds to a data line, a signal line provided to be paired with the data line, a plurality of scanning lines, and an intersection of the data lines and the plurality of scanning lines. Each of the plurality of pixel circuits, and each of the plurality of pixel circuits includes a light emitting element that emits light with a light amount corresponding to a level of the driving current, and a driving transistor that supplies the driving current to the light emitting element. A first transistor provided between a gate and a drain of the driving transistor, a second transistor provided between a gate of the driving transistor and the data line, a gate of the driving transistor, and the signal line And a third transistor provided between and a driving method of a light emitting device,
Each of the plurality of pixel circuits is sequentially selected for a corresponding scanning line only in a horizontal scanning period,
In each of the plurality of pixel circuits,
In a first horizontal scanning period in which another pixel circuit different from the pixel circuit is selected, the first transistor and the third transistor are turned on, the second transistor is turned off, and the source of the drive transistor The voltage of the data line is measured using the voltage between the source and the gate of the driving transistor as the first voltage while a first current flows from the drain to the drain, and a second current is applied from the source to the drain of the driving transistor. , The voltage of the data line is measured as a second voltage between the source and gate of the driving transistor,
The operation of the driving transistor based on the set of the first current and the first voltage and the set of the second current and the second voltage so that the light amount of the light emitting element becomes a gradation indicated by the image data. Correcting the variation in characteristics to generate the data signal corresponding to the gradation indicated by the image data;
In the second horizontal scanning period in which the pixel circuit is selected, the first transistor and the third transistor are turned off, the second transistor is turned on, and the data signal is supplied to the data line.
A driving method of a light-emitting device. Multiple data lines,
A plurality of scan lines;
A data line driving circuit for supplying a data signal to each of the plurality of data lines;
A plurality of pixel circuits provided corresponding to the intersection of the plurality of data lines and the plurality of scanning lines;
Each of the plurality of pixel circuits is provided between a light emitting element that emits light with a light amount corresponding to a level of a driving current, a driving transistor that supplies the driving current to the light emitting element, and a gate and a drain of the driving transistor. And a second transistor provided between the gate or drain of the driving transistor and the data line,
The data line driving circuit includes:
In the measurement period in which the first transistor and the second transistor are in the ON state, the first current is supplied from the source to the drain of the driving transistor, and the voltage of the data line is set between the source and the gate of the driving transistor. And measuring the voltage of the data line as the second voltage between the source and gate of the driving transistor while passing a second current from the source to the drain of the driving transistor. Means,
The operation of the driving transistor based on the set of the first current and the first voltage and the set of the second current and the second voltage so that the light amount of the light emitting element becomes a gradation indicated by the image data. Signal generation means for correcting the variation in characteristics and generating the data signal according to the gradation indicated by the image data;
A light emitting device characterized by that. The second transistor is provided between a drain of the driving transistor and the data line;
The first transistor is provided between a gate of the driving transistor and the data line;
6. The light emitting device according to claim 5, wherein a gate and a drain of the driving transistor are connected by a path including the first transistor, the data line, and the second transistor. Multiple data lines,
A plurality of signal lines provided to be paired with the plurality of data lines;
A plurality of scan lines;
A data line driving circuit for supplying a data signal to each of the plurality of data lines;
A plurality of pixel circuits provided corresponding to the intersection of the plurality of data lines and the plurality of scanning lines;
Each of the plurality of pixel circuits is provided between a light emitting element that emits light with a light amount corresponding to a level of a driving current, a driving transistor that supplies the driving current to the light emitting element, and a gate and a drain of the driving transistor. A first transistor, a second transistor provided between the gate of the driving transistor and the data line, and a third transistor provided between the gate of the driving transistor and the signal line. And
The data line driving circuit includes:
In the measurement period in which the first transistor and the third transistor are turned on and the second transistor is turned off, the voltage of the data line is supplied while flowing a first current from the source to the drain of the driving transistor. The voltage between the source and gate of the driving transistor is measured as a first voltage, and a second current is passed from the source to the drain of the driving transistor, while the voltage of the data line is set to the source and gate of the driving transistor. Measuring means for measuring as the second voltage between,
The operation of the driving transistor based on the set of the first current and the first voltage and the set of the second current and the second voltage so that the light amount of the light emitting element becomes a gradation indicated by the image data. A writing period in which variation in characteristics is corrected to generate the data signal corresponding to the gradation indicated by the image data, the first transistor and the third transistor are turned off, and the second transistor is turned on Signal generating means for supplying the data signal to the data line.
A light emitting device characterized by that. The measuring means includes
A first current source for generating the first current;
A second current source for generating the second current;
A selection circuit that selects and supplies the first current and the second current to the data line in the measurement period;
A first sample and hold circuit that samples the voltage of the data line in a period in which the selection circuit selects the first current, holds the sampled voltage, and outputs the first voltage;
A second sample-and-hold circuit that samples the voltage of the data line during a period in which the selection circuit selects the second current, holds the sampled voltage, and outputs the second voltage;
The light-emitting device according to claim 5, further comprising: The signal generating means includes
Based on the set of the first current and the first voltage and the set of the second current and the second voltage, the voltage of the data signal corresponding to the maximum gradation of the image data and the minimum rank of the image data Voltage generating means for generating a voltage of the data signal corresponding to the key;
Correction means for correcting variations in operating characteristics of the drive transistor based on the voltage generated by the voltage generation means and generating the data signal corresponding to the gradation indicated by the image data;
The light-emitting device according to claim 5, further comprising:   An electronic apparatus comprising the light-emitting device according to claim 5. A plurality of data lines, a plurality of scanning lines, and a plurality of pixel circuits provided corresponding to intersections of the plurality of data lines and the plurality of scanning lines, each of the plurality of pixel circuits being driven A light-emitting element that emits light with a light amount corresponding to a current level; a drive transistor that supplies the drive current to the light-emitting element; a first transistor provided between a gate and a drain of the drive transistor; and the drive transistor A data line driving circuit for supplying a data signal to each of the plurality of data lines, which is used in a light emitting device having a second transistor provided between the gate or drain of the data line and the data line,
In the measurement period in which the first transistor and the second transistor are in the ON state, the first current is supplied from the source to the drain of the driving transistor, and the voltage of the data line is set between the source and the gate of the driving transistor. And measuring the voltage of the data line as the second voltage between the source and gate of the driving transistor while passing a second current from the source to the drain of the driving transistor. Means,
The operation of the driving transistor based on the set of the first current and the first voltage and the set of the second current and the second voltage so that the light amount of the light emitting element becomes a gradation indicated by the image data. Signal generation means for correcting the variation in characteristics and generating the data signal according to the gradation indicated by the image data;
A data line driving circuit characterized by the above. A plurality of data lines, a plurality of signal lines provided to be paired with the plurality of data lines, a plurality of scanning lines, and provided corresponding to intersections of the plurality of data lines and the plurality of scanning lines. Each of the plurality of pixel circuits, and each of the plurality of pixel circuits includes a light emitting element that emits light with a light amount corresponding to a level of a driving current, a driving transistor that supplies the driving current to the light emitting element, and the driving A first transistor provided between the gate and drain of the transistor; a second transistor provided between the gate of the drive transistor and the data line; and between the gate of the drive transistor and the signal line. A data line driving circuit for supplying a data signal to each of the plurality of data lines.
In the measurement period in which the first transistor and the third transistor are turned on and the second transistor is turned off, the voltage of the data line is supplied while flowing a first current from the source to the drain of the driving transistor. The voltage between the source and gate of the driving transistor is measured as a first voltage, and a second current is passed from the source to the drain of the driving transistor, while the voltage of the data line is set to the source and gate of the driving transistor. Measuring means for measuring as the second voltage between,
The operation of the driving transistor based on the set of the first current and the first voltage and the set of the second current and the second voltage so that the light amount of the light emitting element becomes a gradation indicated by the image data. A writing period in which variation in characteristics is corrected to generate the data signal corresponding to the gradation indicated by the image data, the first transistor and the third transistor are turned off, and the second transistor is turned on Signal generating means for supplying the data signal to the data line.
A data line driving circuit characterized by the above.

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