JP2010266498A - Electro-optical device, driving method thereof, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To vary the execution time of mobility compensation for each unit circuit.
An electro-optical device controls a light emitting element that emits light with a light amount corresponding to the magnitude of a driving current, a driving transistor that outputs a driving current to the light emitting element, and whether or not the driving current is supplied to the driving transistor itself. A plurality of unit circuits including one transistor and a data writing transistor having one end connected to the gate of the driving transistor and the other end connected to the data line are provided. Each of the various transistors is controlled by a control signal supplied to each wiring included in the scanning line. In the mobility compensation operation, when the first transistor is turned on, As the control signal, the first control signal (GEL [i]) including the ramp waveform is used.
[Selection] Figure 4

Description

  The present invention relates to an electro-optical device including a light-emitting element such as an organic EL (electroluminescent) element, a driving method thereof, and an electronic apparatus method including the electro-optical device.

As a thin and light-emitting source, there is an organic light emitting diode (OLED), that is, an organic EL element. The organic EL element has a structure in which at least one organic thin film containing an organic material is sandwiched between a pixel electrode and a counter electrode. Among these, the pixel electrode functions as, for example, an anode, and the counter electrode functions as a cathode. When a current is passed between the two, recombination between electrons and holes occurs in the organic thin film, whereby the organic thin film or the organic EL element emits light.
As such an organic EL element or an image display device provided with the organic EL element, those disclosed in Patent Documents 1 and 2, for example, are known.

JP 2007-133283 A

By the way, the organic EL element as described above is driven by a drive circuit having an appropriate configuration. As a drive circuit, for example, there is a circuit that supplies an organic EL element with a current flowing between a source and a drain in accordance with a gate potential of a drive transistor. In this case, the light emission luminance of the organic EL element can be adjusted by adjusting the gate potential.
However, such a drive circuit has various problems to be solved. For example, one of them is variation in various characteristics such as mobility of the driving transistor or threshold voltage. The above-described image display device is usually provided with a drive circuit including a large number of organic EL elements and the drive transistors associated with each of the organic EL elements, and these multiple drives are caused by variations in various parameters in the manufacturing process. If the characteristics of the transistors vary, there will also be variations in the adjustment of the light emission luminance of each organic EL element, resulting in an obstacle to improving the quality of the displayed image.

Patent Document 1 discloses a technique related to such a problem. That is, Patent Document 1 discloses mobility compensation in a drive circuit having a configuration in which a light emission control transistor, a drive transistor, and an organic EL element are connected in series, and a data potential writing transistor is connected to the gate of the drive transistor. Techniques for performing operations are disclosed. In Patent Document 1, this mobility compensation operation is performed by the following two operations: [1] An operation in which the light emission control transistor is turned off and the data writing transistor is turned on to write the data potential to the former gate ( Writing operation) and [2] an operation (light emission operation) in which the light emission control transistor is turned on, the data writing transistor is turned off, and a current derived from the drive transistor is supplied to the organic EL element. Specifically, [3] includes a step of turning on both the light emission control transistor and the data writing transistor and causing a current corresponding to mobility to flow through the driving transistor (see “FIG. 5” in Patent Document 1). Between T6 "and" T7 "or [0031] etc.).
By the operation [3], the source potential of the driving transistor is increased by the current flowing through the driving transistor. As a result, the gate-source voltage is reduced, but the attenuation of the current depends on the mobility of each driving transistor. As a result, if the operation of [3] is executed for each driving transistor for the same time, the gate-source voltage has a value corresponding to the magnitude of the mobility. (In other words, variations in mobility characteristics regarding individual driving transistors are compensated).

However, the technique of Patent Document 1 has the following problems. That is, in order to suitably perform the operation [3], the length of the execution time is extremely important. That is, the time during which the light emission control transistor that defines between [1] and [3] is turned on and the data writing transistor that defines between [3] and [2] are turned off. The time to state must be accurately managed for each drive circuit. Otherwise, for each drive transistor, the degree of current attenuation described above will be scattered, such as being too much for some and not enough for some, ensuring the intended mobility compensation effect. It will not be done.
However, it is generally difficult to accurately perform such time management. For example, if the drive circuits are arranged in a matrix, it is necessary to supply a control signal for turning off the data write transistors arranged in a row to the data write transistors. Due to the presence of parasitic capacitance, parasitic resistance, etc. in the control signal supply line, the waveform of the signal is distorted as it propagates through the supply line, and as a result, the drive circuit is located at the beginning of the row and located at the end. This may cause a difference in the opening / closing time of the data writing transistor.

An object of the present invention is to provide an electro-optical device, a driving method thereof, and an electronic apparatus that can solve at least a part of the problems described above.
Another object of the present invention is to provide an electro-optical device, a driving method thereof, and an electronic apparatus that can solve the problems related to the electro-optical device, the driving method thereof, and the electronic apparatus. To do.

  In order to solve the above-described problem, an electro-optical device according to an aspect of the invention includes a plurality of unit circuits provided corresponding to intersections of a plurality of scanning lines and a plurality of data lines, and each of the plurality of scanning lines. And a scanning line driving circuit that supplies a control signal for controlling the unit circuit, wherein each of the plurality of unit circuits emits light with a light amount corresponding to the magnitude of the driving current. A driving transistor that outputs the driving current in response to a data potential supplied through the data line being supplied to the gate, and a first transistor that controls whether or not the driving current flows through the driving transistor And a switching element having one end connected to the gate of the driving transistor and the other end connected to the data line, each of the plurality of scanning lines extending in the direction of the scanning line Including a first control line serving as a transmission path of the first control signal as the control signal that commands the transition between the conductive state and the non-conductive state of the first transistor to the gates of the first transistors arranged along The scanning line driving circuit supplies the first control signal including a ramp waveform for bringing the first transistor into a conductive state to the first control line at a predetermined timing.

According to the present invention, the first control signal including the ramp waveform is supplied to the first control line. More specifically, in the “ramp waveform” here, first, a transition from one level to another level has a predetermined slope (not vertically) or a predetermined transition time. The part to be carried out, secondly, the part in which the other level after the transition is maintained for a certain period, and thirdly, the transition from the other level to the one level (not vertically) is predetermined. A waveform including three portions, that is, a portion performed with an inclination or with a predetermined transition time is included. In this case, it is assumed that the first transistor becomes conductive at the other level.
In the present invention, the first control signal including such a ramp waveform is supplied to the first control line at a predetermined timing. In this case, since the ramp waveform includes the waveform as described above, even if the first control line has a parasitic resistance, a parasitic capacitance, or the like, the waveform of the first control signal is distorted at the base end and the terminal end. Is very unlikely. Therefore, if the “predetermined timing” is, for example, “timing for performing the mobility compensation operation”, the management of the execution time can be performed very accurately for all unit circuits.

In the electro-optical device according to the aspect of the invention, each of the plurality of scanning lines includes conduction and non-conduction of the switching element that determines whether to supply the data potential to the gate of the driving transistor in addition to the first control line. A second control line serving as a transmission path of a second control signal as the control signal that commands transition between states, and the scanning line driving circuit sets the switching element in a conductive state to the second control line. During the supply of the second control signal, the first control signal including the ramp waveform may be supplied to the first control line.
According to this aspect, the first control signal including the ramp waveform that makes the first transistor conductive is supplied to the first control line while the switching element is conductive. As a result, a data potential is supplied to the gate of the driving transistor, and a current flows between the source and drain thereof. Since the magnitude or attenuation of the current depends on the mobility of the driving transistor, if the time for which the first transistor is in a conductive state is constant for a predetermined time for all unit circuits. Thus, the mobility compensation operation for all the driving transistors is preferably executed.
In this regard, according to the present invention, as described above, the time for turning on the first transistor is determined by the first control signal including the ramp waveform, so the mobility compensation is performed. The time to do is managed accurately. Therefore, according to this aspect, a more preferable or more effective mobility compensation operation is performed.

Further, particularly in this aspect, the first control signal including the ramp waveform is supplied to the first control line during the “middle” in which the switching element is in the conductive state. That is, according to this, the state of the write signal is either high level or low level (which is determined depending on which level the “switching element” is in the conductive state). While maintained, the first transistor transitions from a non-conducting state to a conducting state and from a conducting state to a non-conducting state. For this reason, in this aspect, the mobility compensation operation is performed only based on whether or not the first control signal including the ramp waveform is supplied.
Thus, in this aspect, the execution of the mobility compensation operation is governed by one behavior of the first transistor or one behavior of the first control signal. For example, a plurality of transistors are involved. As a result, the control mode is further simplified as compared with the case where the execution time of the mobility compensation operation is defined.

In the electro-optical device according to the aspect of the invention, the ramp waveform has a transition time until the first control signal reaches from one level to another level, Ts1, and from the other level to the one level. In the case where the transition time is Ts2, and the time from the start time of Ts1 to the end time of Ts2 is Ta,
(Ts1 + Ts2) / Ta> 0.5
It is also possible to configure so as to be established.
According to this aspect, it means that the time during which another level is maintained in the ramp waveform is less than half of the total time Ta. In other words, the ratio of the transition times Ts1 and Ts2 to the total time Ta is larger.
Thus, if the transition times Ts1 and Ts2 become longer, it can be said that the influence of the distortion described above on the ramp waveform becomes relatively smaller. Therefore, according to this aspect, the above-described operational effects according to the present invention are more effectively achieved.
Incidentally, in such a case (or regarding the present invention in general), it is not necessary that both the transition times Ts1 and Ts2 as described above coincide with each other. That is, Ts1 ≠ Ts2.

  According to another electro-optical device of the present invention, in order to solve the above problem, a plurality of unit circuits provided corresponding to intersections of a plurality of scanning lines and a plurality of data lines, and each of the plurality of scanning lines. An electro-optical device including a scanning line driving circuit for supplying a control signal for controlling the unit circuit and a power supply line, wherein each of the plurality of unit circuits includes a light emitting element, the light emitting element, A drive transistor interposed between the power supply line, a first transistor interposed between the power supply line and the drive transistor, one end connected to the gate of the drive transistor, and the other end A switching element connected to the data line, and each of the plurality of scanning lines is electrically connected to a gate of the first transistor arranged along the extending direction of the scanning line. Including The scanning line driving circuit includes a shift register that generates a transfer pulse by transferring a start pulse according to a clock signal, and a circuit that generates a ramp waveform triggered by the transfer pulse and supplies the ramp waveform to the first control line. .

According to the present invention, since the scanning line driving circuit generates a ramp waveform and supplies it to the first control line, it is substantially the same as the operational effect achieved by the electro-optical device according to the present invention described at the beginning. An effect is produced.
In the present invention, the ramp waveform is generated with the transfer pulse as an “opportunity”, and the term “trigger” includes a certain period of time between the generation of the transfer pulse and the generation of the ramp waveform. This implies that a delay or the like may be set, that is, a delay circuit or the like may be provided between them.

Moreover, in order to solve the above-described problems, an electronic apparatus according to the present invention includes the various electro-optical devices described above.
Since the electronic apparatus of the present invention includes the various electro-optical devices described above, high-quality image display can be performed while the mobility compensation operation is suitably executed.

  On the other hand, in the driving method of the electro-optical device of the present invention, in order to solve the above-described problem, a light emitting element that emits light with a light amount corresponding to the magnitude of the driving current and the driving current according to the data potential supplied to the gate A drive transistor that outputs a light source, and a light emission control transistor that controls whether or not the drive current flows to the drive transistor itself, wherein one end is connected to the gate of the drive transistor. The first step of supplying the data potential to the gate of the drive transistor by turning on the switching element connected to the data line for supplying the data potential at the other end, and the light emission control during the first step The light emission control transistor is turned on by a light emission control signal including a ramp waveform that makes the transistor conductive. And a second step.

  According to the present invention, the same operational effects as the operational effects achieved by the electro-optical device of the present invention described above can be achieved.

1 is a block diagram illustrating an electro-optical device according to an embodiment of the invention. It is a circuit diagram which shows the detail of the unit circuit which comprises an organic EL apparatus. It is a block diagram which shows the detail of a scanning line drive circuit. 3 is a timing chart for explaining the operation of the unit circuit of FIG. 2. A light-distortion control transistor (Tel) located far from the scanning line driving circuit (103) is supplied with a signal having a larger distortion than that of a light-emission control transistor (Tel) located near the scanning line driving circuit (103). It is explanatory drawing for demonstrating that such a concern decreases in this embodiment. FIG. 11 is a graph showing changes in the drain-source current of a driving transistor with respect to the time for executing the mobility compensation operation (driving transistors Tdr [A] to Tdr [C] having different mobility). Parameter). It is explanatory drawing for demonstrating a suitable ramp waveform. It is a perspective view which shows the electronic device to which the organic electroluminescent apparatus which concerns on this invention is applied. It is a perspective view which shows the other electronic device to which the organic EL apparatus which concerns on this invention is applied. It is a perspective view which shows the further another electronic device to which the organic EL apparatus which concerns on this invention is applied.

  Hereinafter, an embodiment according to the present invention will be described with reference to FIGS. In addition to FIGS. 1 to 3 referred to here, in each drawing referred to below, the ratio of dimensions of each part may be appropriately different from the actual one.

  As shown in FIG. 1, the organic EL device 100 includes an element substrate 7 and various elements formed on the element substrate 7. The various elements are the organic EL element 8, the scanning line 3 and the data line 6, the power supply line 113, the scanning line driving circuit 103, and the data line driving circuit 106.

A plurality of organic EL elements (light emitting elements) 8 are provided on an element substrate 7 as shown in FIG. The plurality of organic EL elements 8 are arranged in a matrix of N rows × M columns (N and M are natural numbers). Each of the organic EL elements 8 includes a pixel electrode as an anode, a light emitting functional layer, and a counter electrode as a cathode.
The image display area 7 a is an area where the plurality of organic EL elements 8 are arranged on the element substrate 7. In the image display area 7 a, a desired image can be displayed based on individual light emission and non-light emission of each organic EL element 8. Hereinafter, the area excluding the image display area 7a on the surface of the element substrate 7 is referred to as a “peripheral area”.

The scanning lines 3 and the data lines 6 are arranged so as to correspond to the respective rows and columns of the organic EL elements 8 arranged in a matrix. More specifically, as shown in FIG. 1, the scanning line 3 extends in the left-right direction in the drawing and is connected to a scanning line driving circuit 103 formed on the peripheral region. On the other hand, the data line 6 extends along the vertical direction in the drawing and is connected to the data line driving circuit 106 formed on the peripheral region. The power supply line 113 is arranged in parallel with the data line 6. A high power supply potential Vel is supplied to the power supply line 113.
Among the above, the scanning line driving circuit 103 is a circuit for selecting each of the scanning lines 3 in order. The data line driving circuit 106 is a circuit for supplying a data signal through each data line 6 toward each organic EL element 8 corresponding to the scanning line 3 selected by the scanning line driving circuit 103.

In the vicinity of each intersection of each scanning line 3 and each data line 6, a unit circuit (pixel circuit) P including the above-described organic EL element 8 and the like is provided.
As shown in FIG. 2, the unit circuit P includes the organic EL element 8, and also includes a drive transistor Tdr, a light emission control transistor Tel, first to third transistors Tr1 to Tr3, and a capacitive element C1.
Incidentally, the scanning line 3 shown as one wiring for convenience in FIG. 1 actually includes four wirings as shown in FIG. A predetermined signal is supplied from the scanning line driving circuit 103 to each wiring. More specifically, each of these wirings is supplied with a scanning signal GWRT [i], a first compensation control signal GINI1 [i], a second compensation control signal GINI2 [i], and a light emission control signal GEL [i]. Is done. The specific significance of each signal and the operation of the unit circuit P corresponding to this will be described later. The symbol i used here means a row number in the matrix array (see FIG. 1. Since one scanning line 3 is composed of four wirings, it is included in all scanning lines 3. The number of wires is 4N after all.)

The present embodiment is particularly characterized in that the light emission control signal GEL [i] among the various signals described above includes a ramp waveform having a predetermined shape, which will be described later.
Further, the scanning line driving circuit 103 described above includes shift registers SL1 to SL4 corresponding to the various signals, as shown in FIG. Each of the shift registers SL1 to SL4 includes a plurality of unit shift circuits (not shown). When the first stage unit shift circuit receives the start pulse, each of the plurality of unit shift circuits A transfer pulse emitted from the preceding stage to the subsequent stage is generated. Various signals such as the scanning signal GWRT [i] are supplied to each row of the unit circuits P arranged in a matrix in response to the transfer pulse.
Incidentally, the light emission control signal GEL [i] may include a ramp waveform as described above, but the GEL shift register SL4 is provided with a ramp waveform generation circuit V corresponding to this. When the original light emission control signal that is the basis of the light emission control signal GEL [i] generated from the GEL shift register SL4 is input to the ramp waveform generation circuit V, the light emission control signal GEL [i] It will contain the waveform. However, as shown in the figure, there is also a path for avoiding the ramp waveform generation circuit V. When the original emission control signal is not input to the ramp waveform generation circuit V, the emission control signal GEL [i] not including the ramp waveform is It is supplied to the unit circuit P.
Although not shown in FIG. 3, other circuits such as a level shifter are arranged between the ramp waveform generation circuit V and the scanning line 3 or between the GEL shift register SL4 and the ramp waveform generation circuit V. May be.

The driving transistor Tdr is an n-channel type and is on a path from the power supply line 113 to the pixel electrode of the organic EL element 8. The drain (D) of the drive transistor Tdr is connected to the source of the light emission control transistor Tel.
The drive transistor Tdr has a conduction state (resistance value between the source and drain) between the source (S) and the drain (D) that changes according to the gate potential Vg, so that the drive current Iel according to the gate potential Vg is obtained. Means for generating. Note that the gate potential Vg depends on the magnitude of the data signal Data supplied through the data line 6.
Thus, the organic EL element 8 is driven according to the conduction state of the drive transistor Tdr or the data signal Data.

The light emission control transistor Tel is a p-channel type, and is located between the driving transistor Tdr and the power supply line 113. The light emission control signal GEL [i] is supplied to the gate of the light emission control transistor Tel. When the light emission control signal GEL [i] transitions to a low level, the light emission control transistor Tel changes to an ON state, and the drive current Iel can be supplied to the organic EL element 8. As a result, the organic EL element 8 emits light with a gradation (luminance) corresponding to the drive current Iel. On the other hand, when the light emission control signal GEL [i] is at a high level, the light emission control transistor Tel is maintained in the OFF state, so that the path of the drive current Iel is blocked and the organic EL element 8 is turned off.
The pixel electrode of the organic EL element 8 is connected to the power supply line 113 to which the above-described high power supply potential Vel is supplied via the light emission control transistor Tel and the drive transistor Tdr, and the counter electrode has a low power supply potential VCT. It is connected to a potential line (not shown) to be supplied. The light emission control transistor Tel controls the presence / absence of current supply to the organic EL element 8 as described above, and accordingly, also controls the current flow to the driving transistor Tdr itself. Can be seen.

  The capacitive element C1 is an element in which a dielectric is interposed between two electrodes. Its capacitance value is Ch1. One electrode (upper electrode in the figure) of the capacitive element C1 is connected to the gate of the drive transistor Tdr. The other electrode (lower electrode in the figure) of the capacitive element C1 is connected to the source (S) of the driving transistor Tdr and also to the source of a third transistor Tr3 described later.

The first transistor Tr1 is a switching element that is interposed between the node Z1 and the data line 6 and controls the electrical connection therebetween. The scanning signal GWRT [i] is supplied to the gate of the first transistor Tr1.
The second transistor Tr2 is a switching element that is provided between the node Z1 and the potential line to which the initialization potential VST is supplied and controls the electrical connection between them. The first compensation control signal GINI1 [i] is supplied to the gate of the second transistor Tr2.
The third transistor Tr3 is a switching element that is provided between the supply line of the initialization potential VINI and the source of the drive transistor Tdr and controls the electrical connection between them. The second compensation control signal GINI2 [i] is supplied to the gate of the third transistor Tr3.

Next, the operation or action of the organic EL device 100 having the above configuration will be described with reference to FIGS. 4 to 6 in addition to FIGS. 1 and 2 already referred to.
[I] Initialization: First, when the first compensation control signal GINI1 [i] and the second compensation control signal GINI2 [i] become high level, the second transistor Tr2 and the third transistor Tr3 are turned on. As a result, the gate potential Vg and the source potential Vs of the drive transistor Tdr drop as shown in FIG. 4 to become the initialization potential VST and VINI, respectively.
The unit circuit P repeatedly performs each operation from [i] initialization described above to [v] driving described later. The initialization operation [i] is performed after the last [v] driving operation (light emission operation), that is, after the light emission control signal GEL [i] transitions from a low level to a high level. The decrease in both the gate potential Vg and the source potential Vs prior to the decrease in the source potential Vs shown in the leftmost part of FIG. 4 corresponds to such a transition of the light emission control signal GEL [i].

[Ii] Vth compensation: Next, the second compensation control signal GINI2 [i] transitions to a low level, and then the light emission control signal GEL [i] transitions to a low level. Thereby, the third transistor Tr3 is turned off, and further, the light emission control transistor Tel is turned on. For this reason, the source potential Vs is released from the supply of the initialization potential VST. As a result, the source potential Vs of the drive transistor Tdr starts to rise as shown in FIG. 4 together with the conduction state between the drive transistor Tdr and the high power supply potential Vel, and the gate-source voltage is the threshold voltage. Asymptotic to Vth. Note that, during this series of processes, the capacitive element C1 connected between the gate and source of the driving transistor Tdr holds the threshold voltage Vth (note that the capacitive element C1 is appropriately changed depending on the time even in the following operations. Hold the voltage.)
As described above, in the operation in [ii], the threshold voltage Vth of each drive transistor Tdr is compensated.

[Iii] Data writing: Next, the light emission control signal GEL [i] and the first compensation control signal GINI1 [i] transition to the high level and the low level, respectively, and the light emission control transistor Tel and the second transistor Tr2 On the other hand, when the scanning signal GWRT [i] becomes high level, the first transistor Tr1 is turned on. At this time, when a data signal having an appropriate data potential Vdata is supplied through the data line 6, the potential of the node Z1, that is, the gate potential Vg, fluctuates by a voltage corresponding to the added amount of the data potential Vdata. To do. Therefore, the gate-source voltage of the driving transistor Tdr is Vth + Vdata ′ as shown in FIG. Here, Vdata ′ = Vdata · (Ch2 / (Ch2 + Ch1)). In this equation, Ch2 is a capacitance value of the parasitic capacitance of the organic EL element 8.

[Iv] Mobility compensation: Next, while the high level of the scanning signal GWRT [i] is maintained, the light emission control signal GEL [i] starts transitioning to the low level.
In the present embodiment, in particular, the light emission control signal GEL [i] has a ramp waveform as shown in FIG. That is, in this case, the light emission control signal GEL [i] first transitions from the high level state to the low level state, and secondly, after reaching the low level state. The state is maintained for a while, and thirdly, a transition is made from this low level state to a gently high level state. At this time, the ramp waveform generation circuit V shown in FIG. 3 is used. Accordingly, the light emission control transistor Tel is turned on when the light emission control signal GEL [i] is equal to or lower than a predetermined level in the first transition described above, and when the light emission control signal GEL [i] is equal to or higher than the predetermined level in the third transition. It will be in the OFF state.
Thus, the light emission control transistor Tel is turned on again only during the time when the light emission control signal GEL [i] is equal to or lower than the predetermined level, so that the source potential Vs of the drive transistor Tdr starts to rise. In FIG. 4, it is expressed that the gate-source voltage after the increase of the source potential Vs becomes Vth + Va, but this indicates that the increase of the source potential Vs can be expressed as “Vdata′−Va”. It means that. As a result, on the contrary, the gate-source voltage of the driving transistor Tdr is reduced.
In general, the degree of the increase in the source potential Vs or the decrease in the voltage between the gate and the source differs depending on each of the driving transistors Tdr included in each unit circuit P having different mobility characteristics. It will be. That is, qualitatively, the drive transistor Tdr having a larger mobility μ has a large increase amount of the source potential Vs, and the drive transistor Tdr having a smaller mobility μ has a small increase amount of the source potential Vs.
As described above, in the operation in [iv], the mobility compensation of each driving transistor Tdr is performed.
The significance, action, effect, etc. of the ramp waveform described here will be described later.

[V] Driving: The scanning signal GWRT [i] transitions to a low level and the first transistor Tr1 is turned off, while the light emission control signal GEL [i] is set to a low level three times, thereby causing the light emission control transistor Tel. Is turned on. Thereby, the organic EL element 8 is supplied with the drive current Iel having a magnitude corresponding to the gate potential Vg from the drive transistor Tdr, and the organic EL element 8 emits light.

Next, the ramp waveform of the light emission control signal GEL [i] described above will be described with reference to FIGS.
In the present embodiment, as described above, the light emission control signal GEL [i] having a ramp waveform is used to control the light emission control transistor Tel, and the significance thereof is as follows.
First, in the organic EL device 100 of the present embodiment, since the unit circuits P are arranged in a matrix as described above (see FIG. 1), the light emission control transistors Tel are similarly arranged in a matrix. Therefore, a plurality of light emission control transistors Tel belong to each row of the matrix arrangement as shown in FIG. 5 (only one row is shown in FIG. 5). In order to control such a plurality of light emission control transistors Tel, as described above, one of the four wirings constituting the scanning line 3 is used (see FIG. 2 and its description). 3el also includes a parasitic resistance RK and a parasitic capacitance CK as shown in FIG. Therefore, when any signal is supplied to the wiring 3el, it is considered that the waveform of the signal is distorted due to the presence of the parasitic resistance RK and the parasitic capacitance CK.

  Actually, when the light emission control signal GEL [i] has a “rectangular wave”, the light emission control transistor Tel located near the scanning line driving circuit 103 as a signal supply source has a light emission control having a desired rectangular wave. Although the signal GEL [i] can be supplied, it becomes difficult for the light-emission control transistor Tel located further away. That is, as shown in the drawing, it may occur that the time when the signal reaches a predetermined level is delayed both at the falling edge of the signal and at the rising edge. Such a tendency tends to become more noticeable as the distance from the scanning line driving circuit 103 increases. In this case, the time for maintaining the light emission control transistor Tel in the ON state varies with respect to each light emission control transistor Tel.

However, it is bad that such a situation occurs with respect to the mobility compensation operation [iv]. This is because, as described above, the mobility compensation operation according to the present embodiment is based on the premise that the degree of increase in the source potential Vs is adjusted according to the mobility of each drive transistor Tdr. This is because the purpose is finally to compensate for such variation in mobility by appropriately setting the time for executing the mobility compensation operation.
That is, as shown in FIG. 6, when the mobility characteristics deteriorate in the order from the drive transistor Tdr [A] to Tdr [C], a current is passed through these drive transistors Tdr [A] to Tdr [C]. The degree of attenuation increases in this order. Then, it is assumed that there is a region XR in which each curve shown in FIG. 6 representing the variation in mobility related to these drive transistors Tdr [A] to Tdr [C] is within a certain range.
The optimum mobility compensation time T1 is suitably set on the assumption of the existence of such a region XR (see FIG. 6).

However, if the optimum mobility compensation time T1 changes due to the distortion of the light emission control signal GEL [i] as described with reference to FIG. 5, the optimum mobility compensation operation is no longer performed. It becomes difficult. In FIG. 6, although the mobility compensation time is originally intended to be T1, if it becomes T2 shorter than that, the driving transistor Tdr [ The case where the mobility compensation operation of A] is completed is illustrated. In FIG. 5, the drive transistor Tdr [A] in such a case is included in the unit circuit P including the light emission control transistor Tel located on the rightmost side of the figure farther from the scanning line drive circuit 103. It is easy to assume that it can be.
Eventually, when this happens, the possibility of optimal mobility compensation for each drive transistor Tdr is extremely low.

  In this respect, in the present embodiment, as described above, the mobility compensation operation is performed based on the light emission control signal GEL [i] having a ramp waveform. Is done. This is because in this case, as shown in FIG. 5, since the ramp waveform has a slope-like transition band, the light emission control signal GEL [i] is not significantly distorted. Even in this case, as the distance from the scanning line driving circuit 103 increases, the signal delay may occur (see the ramp waveform indicated by the broken line in FIG. 5). Does not have a significant effect. In order to avoid the adverse effect due to this delay, for example, the time tw for maintaining the scanning signal GWRT [i] at the high level shown in FIG. 4 may be adjusted as appropriate. Specifically, for example, the time tw may be long enough to wrap around the entire ramp waveform by delaying the falling edge at the right end in FIG.

  In this way, according to the present embodiment, the period during which the light emission control transistor Tel is maintained in the ON state is preferably managed regardless of the position of the light emission control transistor Tel as viewed from the scanning line driving circuit 103. Therefore, the mobility compensation operation in the present embodiment is extremely effectively performed.

According to the organic EL device 100 or the unit circuit P as described above, the following effects are exhibited.
(1) First, according to the unit circuit P of the present embodiment, as described above, the light emission control signal GEL [i] having a ramp waveform is used in the mobility compensation operation. Based on the above, a suitable mobility compensation operation is performed. Thereby, the variation in the light emission luminance of each organic EL element 8 is suppressed, and a higher quality image display becomes possible.

(2) In the present embodiment, the mobility compensation operation (particularly the execution time thereof) is one behavior of the light emission control transistor Tel or one behavior of the light emission control signal GEL [i] as described above. Therefore, the above-described effect (1) can be more effectively achieved, and the control mode can be simplified.
For example, in the prior art, a method for determining the execution time of mobility compensation by appropriately associating transitions between ON and OFF of various transistors as shown in FIG. 2 may be used. For example, as described in the section of [Problems to be solved by the invention], [1] The light emission control transistor is turned off and the data writing transistor is turned on. [3] The light emission control transistor and the data writing transistor When performing the operations [1] → [3] → [2] in which both the transistors are turned on, [2] the light emission control transistor is turned on, and the data writing transistor is turned off. The mobility compensation time includes the transition of the light emission control transistor from the off state to the on state ([1] → [3]) and the transition of the data writing transistor from the on state to the off state ([3] → [ 2]).
However, in the case where a plurality of transistors are involved in this way, there is no concern that distortion or delay as shown in FIG. 5 will occur with respect to each of the signals for controlling each of the transistors. Don't be. As a result, in managing the mobility compensation time, it is necessary to take into account the relationship between the two signals (for example, which delay is greater), so the mobility compensation time is maintained optimally. To do that comes with greater difficulty.

  From this point of view, the present embodiment is more advantageous. This is because, as described above, in this embodiment, the mobility compensation time is determined by one behavior of the light emission control signal GEL [i]. There is no particular need to consider the relationship, etc., because the control or the maintenance of the optimum mobility compensation time can be realized relatively easily.

In the present invention, the (ramp waveform) shape of the “ramp waveform” is basically not particularly limited, but the “ramp waveform” will be described below. If such a condition is satisfied, it is more preferable.
That is, as shown in FIG. 7, the time from the start point to the end point of the ramp waveform is Ta, the transition time from the high level to the low level is Ts1, and the transition time from the low level to the high level is Ts2. Then, it is preferable that (Ts1 + Ts2) / Ta> 0.5 is established between them. In this case, this means that the time during which the low level is maintained in the ramp waveform is less than half of the total time Ta. In other words, the ratio of the transition times Ts1 and Ts2 to the total time Ta is larger.
Thus, if the transition times Ts1 and Ts2 become longer, it can be said that the influence of the distortion described above on the ramp waveform becomes relatively smaller. Therefore, the operational effects according to this embodiment described above are more effectively achieved.
Incidentally, in such a case (or regarding the present invention in general), it is not necessary that both the transition times Ts1 and Ts2 as described above coincide with each other. That is, Ts1 ≠ Ts2 may be satisfied (see FIG. 7).

<Application>
Next, an electronic apparatus to which the organic EL device 100 according to the above embodiment is applied will be described.
FIG. 8 is a perspective view showing a configuration of a mobile personal computer using the organic EL device 100 according to the above embodiment as an image display device. The personal computer 2000 includes an organic EL device 100 as a display device and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002.
FIG. 9 shows a mobile phone to which the organic EL device 100 according to the above embodiment is applied. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the organic EL device 100 as a display device. By operating the scroll button 3002, the screen displayed on the organic EL device 100 is scrolled.
FIG. 10 shows an information portable terminal (PDA: Personal Digital Assistant) to which the organic EL device 100 according to the embodiment is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and the organic EL device 100 as a display device. When the power switch 4002 is operated, various types of information such as an address book and a schedule book are displayed on the organic EL device 100.

  As electronic devices to which the organic EL device according to the present invention is applied, in addition to those shown in FIGS. 8 to 10, a digital still camera, a television, a video camera, a car navigation device, a pager, an electronic notebook, electronic paper, a calculator, Examples include a word processor, a workstation, a videophone, a POS terminal, a video player, and a device equipped with a touch panel.

DESCRIPTION OF SYMBOLS 100 ... Organic EL device, 103 ... Scan line drive circuit, 106 ... Data line drive circuit, P ... Unit circuit (pixel circuit), 8 ... Organic EL element, 3 ... Scan line, 6 ... Data , 113... Power line, Tr1 to Tr3... First to third transistors, C1 to C3... First to third capacitance elements, Tdr... Driving transistor, Tel.

Claims (6)

A plurality of unit circuits provided corresponding to intersections of the plurality of scanning lines and the plurality of data lines; and a scanning line driving circuit for supplying a control signal for controlling the unit circuit to each of the plurality of scanning lines. An electro-optical device comprising:
Each of the plurality of unit circuits is
A light emitting element that emits light with a light amount corresponding to the magnitude of the drive current;
A driving transistor that outputs the driving current in response to a data potential supplied through the data line being supplied to a gate;
A first transistor for controlling whether or not to pass the driving current to the driving transistor;
A switching element having one end connected to the gate of the driving transistor and the other end connected to the data line;
Including
Each of the plurality of scan lines is
It becomes a transmission path of a first control signal as the control signal that commands the transition of the first transistor between the conduction state and the non-conduction state to the gates of the first transistor arranged along the extending direction of the scanning line. Including a first control line;
The scanning line driving circuit includes:
At a given timing
Supplying the first control signal including a ramp waveform to bring the first transistor into a conductive state to the first control line;
An electro-optical device. Each of the plurality of scanning lines includes the first control line,
A second control serving as a transmission path of a second control signal as the control signal for instructing a transition between the conductive state and the non-conductive state of the switching element that determines whether or not to supply the data potential to the gate of the driving transistor; Including lines,
The scanning line driving circuit includes:
During the supply of the second control signal to turn on the switching element to the second control line,
Supplying the first control signal including the ramp waveform to the first control line;
The electro-optical device according to claim 1. The ramp waveform is
The transition time from the first level to the other level of the first control signal is Ts1,
The transition time from the other level to the one level is Ts2,
In the case where the time from the start time of the Ts1 to the end time of the Ts2 is Ta,
(Ts1 + Ts2) / Ta> 0.5
Is established so that
The electro-optical device according to claim 1 or 2. A plurality of unit circuits provided corresponding to intersections of the plurality of scanning lines and the plurality of data lines; and a scanning line driving circuit for supplying a control signal for controlling the unit circuit to each of the plurality of scanning lines. An electro-optical device including a power line,
Each of the plurality of unit circuits is
A light emitting element;
A drive transistor interposed between the light emitting element and the power line;
A first transistor interposed between the power line and the driving transistor;
A switching element having one end connected to the gate of the driving transistor and the other end connected to the data line;
Including
Each of the plurality of scan lines is
A first control line electrically connected to a gate of the first transistor arranged along the extending direction of the scanning line;
The scanning line driving circuit includes:
A shift register that generates a transfer pulse by transferring a start pulse according to a clock signal; and
A circuit that generates a ramp waveform triggered by the transfer pulse and supplies the ramp waveform to the first control line;
Comprising
An electro-optical device. The electro-optical device according to claim 1 is provided.
An electronic device characterized by that. A light emitting element that emits light with a light amount corresponding to the magnitude of the driving current, a driving transistor that outputs the driving current according to a data potential supplied to a gate, and whether or not the driving current is supplied to the light emitting element. A driving method of an electro-optical device including a light emission control transistor,
A first step of supplying the data potential to the gate of the driving transistor by turning on a switching element having one end connected to the gate of the driving transistor and the other end connected to the data line supplying the data potential;
In the middle of the first step, a second step of bringing the light emission control transistor into a conductive state by a light emission control signal including a ramp waveform that turns the light emission control transistor into a conductive state;
A method for driving an electro-optical device.

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