JP2010002801A - El display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EL display with which duty driving to perform luminance adjustment is made possible even when the number of constitution elements of a pixel circuit is little. <P>SOLUTION: A switching transistor 11b is made electrically conductive according to a control signal supplied from a gate signal line 17, samples the signal potential supplied from a source signal line 18 and holds the signal potential in a capacitor 19. A cancellation voltage Vdd_L and a driving voltage Vdd_H are switched and applied to the source terminal of a driving transistor 11a by control of a circuit 23 for power supply to cause a driving transistor 11a to perform a cancellation operation. The output of is switched to/from a cancellation voltage Vdd_L from/to A power source selector 21 selects the output in the driving voltage Vdd_H and the high impedance state, and performs duty driving. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an active matrix EL display device using an electroluminescence (EL) element as a pixel.

  In recent years, development of flat self-luminous EL display devices using EL elements has become active. An EL element is a device that utilizes the phenomenon of light emission when an electric field is applied to an organic thin film.

  Since the EL element is a self-luminous element that emits light by itself, it does not require a lighting member and can be easily reduced in weight and thickness. In addition, since the response speed of the EL element is very high, about several microseconds, no afterimage occurs when displaying a moving image.

For organic EL display panels such as PLED, OLED, and OEL, active matrix systems have been actively developed. In this method, a current flowing through a light emitting element in each pixel circuit is controlled by an active element (generally a thin film transistor or TFT) provided in the pixel circuit (see, for example, Patent Documents 1 and 2).
JP 2003-255856 A JP 2003-271095 A

  The organic EL display panel is configured by using a transistor array made of low-temperature or high-temperature polysilicon. However, if there is a characteristic variation in the driving transistor that supplies current to the EL element, the converted current signal also varies. Usually, the transistor has a characteristic variation of 50% or more. Therefore, there is a problem in that the characteristic variation of the driving transistor is displayed as display unevenness, and the image display quality is lowered.

  Further, since the characteristics of the EL element itself change with time, there is a problem that the image display quality is lowered.

  In order to improve image display quality, it is necessary to correct variations in the characteristics of the transistors and EL elements. Conventionally, display devices having a correction function have been proposed. However, the number of components of the pixel circuit is complicated, which hinders high-definition display. Further, even in the duty drive for adjusting the brightness of image display, there is a problem that the constituent elements of the pixel circuit become complicated in order to realize without reducing the display quality.

That is, in order to perform duty driving for adjusting the luminance of the EL display device, the number of constituent elements of the pixel circuit is increased and the layout area is increased, which is not suitable for high-definition display. ,
Therefore, the present invention provides an EL display device capable of performing duty drive for adjusting luminance even when the number of constituent elements of a pixel circuit is small.

  The present invention provides an EL display device having a display screen in which a plurality of pixels each having an EL element are arranged in a matrix. Each of the pixels has a source terminal connected to the EL element and a drain terminal connected to an anode voltage wiring. A connected driving transistor; a switching transistor connected to a gate terminal of the driving transistor for applying a video signal from a source signal line; a capacitor connected to the gate terminal and the source terminal of the driving transistor; And is arranged between the anode voltage wiring and the power supply circuit, and can be switched between the drive control voltage and the high impedance state. And generating a display area on the display screen when switching to the drive control voltage, By generating a non-display area on the display screen when switching to-impedance state, and a power supply selector for performing duty drive by suppressing the current flowing through the EL element, an EL display device having a.

  According to the present invention, duty drive can be realized by the power supply selector, and the number of pixel constituent elements can be reduced.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
An EL display device according to a first embodiment of the present invention will be described with reference to FIGS.

(1) Overall Configuration of EL Display Device First, the overall configuration of the EL display device will be described with reference to FIG. FIG. 2 is a block diagram showing the overall configuration of the EL display device according to this embodiment.

  The present embodiment includes a display screen 22 in which EL elements 15 are arranged in a matrix and a drive circuit that drives the display screen 22. That is, as shown in FIG. 2, the EL display device selects a display screen 22, a source driver circuit 18 composed of an IC for driving the display screen, a gate driver circuit 12, a power supply circuit 23 for supplying an anode voltage, and an anode voltage. The power supply selector 21 is used.

  The display screen 22 includes row-shaped gate signal lines 17 extending in the horizontal direction, column-shaped source signal lines 18 extending in the vertical direction, pixels 16 arranged in a lattice pattern at the intersections thereof, and rows of the pixels 16. Correspondingly formed anode voltage wiring 20 is provided. That is, the anode voltage wiring 20 is wired in the horizontal direction.

(2) Configuration of Pixel 16 Next, the configuration of the pixel 16 will be described with reference to FIG. FIG. 1 is a circuit diagram showing a specific configuration and connection relationship of the pixels 16 included in the EL display device shown in FIG.

  As shown in FIG. 1, the pixel 16 includes an EL element 15, a switching transistor 11 b, a driving transistor 11 a, and a capacitor 19.

  The gate terminal d of the switching transistor 11b is connected to the gate signal line 17, the drain terminal d is connected to the source signal line 18, and the source terminal is connected to the gate terminal g of the driving transistor 11a.

  The drain terminal d of the driving transistor 11 a is connected to the anode voltage wiring 20, and the source terminal s is connected to the anode terminal of the EL element 15.

  The cathode of the EL element 15 is connected to the ground electrode or the cathode electrode Vss. The voltage of the cathode electrode Vss is also denoted as Vss. The ground electrode or cathode electrode Vss is wired in common to all the pixels 16.

  The capacitor 19 is connected between the source terminal s and the gate terminal g of the driving transistor 11a.

  In the above configuration, the switching transistor 11 b is turned on in response to the control signal supplied from the gate signal line 17, samples the signal potential supplied from the source signal line 18, and holds it in the capacitor 19.

  The driving transistor 11 a receives supply of current from the anode voltage wiring 20, and flows drive current to the EL element 15 in accordance with the signal potential held in the capacitor 19.

(3) Gate driver circuit 12
Next, the gate driver circuit 12 will be described.

  The gate driver circuit 12 sequentially supplies a control signal to each gate signal line 17 to scan the pixels 16 line-sequentially in units of rows. That is, an on voltage or an off voltage is supplied.

  A start pulse ST1 for selecting the gate signal line 17 and a clock signal CLK for sequentially shifting the start pulse are applied to the gate driver circuit 12. A signal UD for switching the direction of the up / down shift register of the start pulse in the gate driver circuit 12 is also applied.

  Note that it is preferable to add an enable control terminal to the gate driver circuit 12 as necessary. A shift register circuit is formed in the gate driver circuit 12, and the start pulse is sequentially shifted in synchronization with the clock signal CLK to change the position of the gate signal line 17 to be selected.

(4) Anode Voltage Control Next, the anode voltage control will be described with reference to FIGS. 1 and 11 to 13.

  A drive voltage Vdd_H or a cancel voltage Vdd_L is applied to the drain terminal d of the drive transistor 11a. Switching between the drive voltage Vdd_H and the cancel voltage Vdd_L is realized by control of the power supply selector 21 and the power supply circuit 23.

  As shown in FIG. 11, when the power selector 21 is selected to the a side, if the output of the power supply circuit 23 is Vdd_H, the potential of the anode voltage wiring 20 becomes Vdd_H, and the power supply circuit 23 Is at Vdd_L, the potential of the anode voltage wiring 20 is Vdd_L.

  Further, the duty drive described with reference to FIGS. 12 and 13 can be realized by switching the power supply selector 21. This duty drive is performed to generate a non-display area and suppress the current flowing through the EL element 15. This will be described in detail later, but briefly explained here, the power selector 21 is switched to generate a strip-like non-display area on the display screen 22, and this non-display area is moved vertically in the screen 22. The image is displayed in synchronization with the frame period.

(5) Threshold voltage correction function Next, the threshold voltage correction function will be described.

  The source driver circuit 18 for supplying a signal voltage to the source signal line 18 is connected to the drain terminal d of the driving transistor 11a while the reference potential V0 is being supplied to the source signal line 18 after the switching transistor 11b is turned on. The voltage applied to is switched between the drive voltage Vdd_H and the cancel voltage Vdd_L, and a voltage corresponding to the threshold voltage Vth of the drive transistor 11 a is held in the capacitor 19.

  With this threshold voltage correction function, the EL display device can cancel the influence of the threshold voltage of the driving transistor 11 a which varies from the pixel 16.

(6) Bootstrap function Next, the bootstrap function will be described. The pixel 16 shown in FIG. 1 further has a bootstrap function.

  The power supply selector 21 and the power supply circuit 23 apply the same voltage to the anode voltage wiring 20 by switching the output from the cancel voltage Vdd_L to the drive voltage Vdd_H when the signal potential is held in the capacitor 19. Therefore, the potential of the drain terminal d of the driving transistor 11a changes from Vdd_L to Vdd_H voltage. Further, the switching transistor 11b is turned off to electrically disconnect the gate terminal g of the driving transistor 11a from the source signal line 18.

  By this operation, the gate potential Vg is interlocked with the fluctuation of the source potential Vs of the driving transistor 11a, and the voltage Vgs between the gate terminal g and the source terminal s can be kept constant.

(7) Timing Chart of Operation of Pixel 16 FIG. 3 is a timing chart for explaining the operation of the pixel 16 shown in FIG. With the time axis in common, the potential change of the gate signal line 17, the voltage change of the anode voltage wiring 20, the potential change of the source signal line 18, and the light emission state of the EL element 15 are schematically shown. Note that this timing chart is divided into periods B to H for convenience in accordance with changes in the operation of the pixels 16.

  In the light emission period B, the EL element 15 is in a light emitting state. Thereafter, a new field of line sequential scanning is entered, and in the first period C, the switching transistor 11b is turned on, and the gate potential Vg of the driving transistor 11a is initialized.

  Next, in period D, the output of the power supply circuit 23 is switched, the cancel voltage Vdd_L is applied to the drain terminal d of the driving transistor 11a, and the source potential Vs of the driving transistor 11a is also initialized. Thus, by preparing the gate potential Vg and the source potential Vs of the driving transistor 11a, the preparation for the threshold voltage correction operation is completed. The Vdd_L voltage is a voltage at which the EL element 15 is not turned on (no current flows) and the driving transistor 11a is turned off.

  Next, in the threshold correction period E, a threshold voltage correction operation is actually performed, and a voltage corresponding to the threshold voltage Vth is held between the gate terminal g and the drain terminal d of the driving transistor 11a. Actually, a voltage corresponding to Vth is written in the capacitor 19 connected between the gate terminal g and the drain terminal d of the driving transistor 11a.

  Next, in the sampling period F, the signal potential Vin of the video signal is written into the capacitor 19 in a form to be added to Vth.

  Next, in the light emission period G, the EL element 15 emits light with a luminance corresponding to the signal voltage Vin. At this time, since the signal voltage Vin is adjusted by a voltage corresponding to the threshold voltage Vth, the light emission luminance of the EL element 15 is not affected by variations in the threshold voltage Vth of the driving transistor 11a.

  Note that a bootstrap operation is performed at the beginning of the light emission period G, and the gate potential Vg and the source potential Vs of the driving transistor 11a rise while the gate-source voltage Vgs = Vin + Vth of the driving transistor 11a is kept constant. .

(8) Operation of Pixel 16 The operation of the pixel 16 shown in FIG. 1 will be described in detail with reference to FIGS. 4 to 10 correspond to the periods B to H in the timing chart shown in FIG. 3, respectively.

(8-1) Light emission period B
As shown in FIG. 4, in the light emission period B, the voltage of the anode voltage wiring 20 becomes Vdd_H, the potential of the drain terminal d of the driving transistor 11a is at the driving voltage Vdd_H, and the driving transistor 11a sets the driving current Ids to EL. This is supplied to the element 15.

  As shown in FIG. 4, the drive current Ids flows from the anode voltage Vdd_H through the drive transistor 11a through the EL element 15 and flows into the common ground electrode or the cathode electrode Vss.

(8-2) Period C
Next, in the period C, as shown in FIG. 5, the potential of the gate signal line 17 changes to the high potential VGH (the ON voltage is applied), so that the switching transistor 11b is turned on, and the driving transistor The gate potential Vg of the transistor 11a is initialized (reset) to the reference potential V0 of the source signal line 18.

(8-3) Period D
Next, in the period D, as shown in FIG. 6, the potential of the drain terminal d of the driving transistor 11a changes from the driving voltage Vdd_H to the cancel voltage Vdd_L that is sufficiently lower than the reference potential V0 of the source signal line 18.

  As a result, the source potential Vs of the driving transistor 11a is initialized (reset or canceled) to a cancel voltage Vdd_L that is sufficiently lower than the reference potential V0 of the source signal line 18.

  Specifically, the drain terminal d of the driving transistor 11a is set so that the gate-source voltage Vgs (the difference between the gate potential Vg and the source potential Vs) of the driving transistor 11a is larger than the threshold voltage Vth of the driving transistor 11a. Is set to the cancel voltage Vdd_L.

(8-4) Threshold correction period E
Next, when proceeding to the threshold correction period E, as shown in FIG. 7, the potential of the drain terminal d of the driving transistor 11a changes from the cancel voltage Vdd_L to the driving voltage Vdd_H, and the source potential Vs of the driving transistor 11a increases. To start.

  Eventually, the current is cut off when the voltage Vgs between the gate terminal and the source terminal of the driving transistor 11a becomes the threshold voltage Vth. In this way, a voltage corresponding to the threshold voltage Vth of the driving transistor 11a is written into the capacitor 19. This is the threshold voltage correction operation. At this time, in order to prevent current from flowing exclusively to the capacitor 19 side and not to the EL element 15 side, the potential of the common ground electrode or the cathode electrode Vss is set so that the EL element 15 is cut off.

(8-5) Sampling period F
Next, in the sampling period F, as shown in FIG. 8, the potential of the source signal line 18 changes from the reference potential V0 to the signal potential Vin at the first timing, and the gate potential Vg of the driving transistor 11a is Vin. It becomes. Therefore, during the sampling period F, the gate-source voltage Vgs of the driving transistor 11a is Vin + Vth.

(8-6) Light emission period G
Finally, in the light emission period G, as shown in FIG. 9, the gate signal line 17 changes to the cancel voltage side, and the switching transistor 11b is turned off. As a result, the gate terminal g of the driving transistor 11 a is disconnected from the source signal line 18. At the same time, the drain current Ids starts to flow through the EL element 15. As a result, the anode potential of the EL element 15 rises according to the drive current Ids.

  The rise in the anode potential of the EL element 15 is nothing but the rise in the source potential Vs of the driving transistor 11a. When the source potential Vs of the driving transistor 11a rises, the gate potential Vg of the driving transistor 11a also rises in conjunction with the bootstrap operation of the capacitor 19. The increase amount of the gate potential Vg is equal to the increase amount of the source potential Vs. Therefore, the gate-source voltage Vgs of the driving transistor 11a is kept constant at Vin + Vth during the light emission period.

(8-7) Quenching period H
In the present embodiment of FIG. 1, the duty drive as shown in FIG. 12B can be realized by controlling the potential of the anode voltage wiring 20. This duty drive is performed to generate a non-display area and suppress the current flowing through the EL element 15. Hereinafter, the duty drive during the extinction period H will be described.

  In the extinction period H, as shown in FIG. 10, the potential of the anode voltage wiring 20 changes from the driving voltage Vdd_H to high impedance. As a result, the power supply from the anode voltage wiring 20 cannot be received, the drive current Ids flowing through the EL element 15 is stopped, and the EL element 15 is turned off. Therefore, in the extinction period H, the EL element 15 is in the extinction state.

  Note that the gate-source voltage Vgs is held by the capacitor 19. When the potential of the anode voltage wiring 20 transitions from the high impedance to the driving voltage Vdd_H again, power is supplied from the anode voltage wiring 20 and the driving current Ids flows, whereby the EL element 15 emits light.

(9) Anode Voltage Control As described above, threshold value correction and duty drive are performed by controlling the potential of the anode voltage wiring 20. The potential of the anode voltage wiring 20 is controlled by switching using a power supply circuit 23 and a power selector 21 as shown in FIG.

  When the power selector 21 is on the a side, if the output of the power supply circuit 23 is Vdd_H, the potential of the anode voltage wiring 20 is Vdd_H, and the output of the power supply circuit 12b is Vdd_L. Then, the potential of the anode voltage wiring 20 becomes Vdd_L. Further, when the power selector 21 is on the b side, the anode voltage wiring 20 becomes high impedance regardless of the output of the power supply circuit 23.

(10) Duty Drive In FIG. 12, the pixel row in which the video signal is written is displayed as the program pixel row 111.

  The non-display area 113 indicates a pixel row or a group of pixel rows that are not displayed by setting the power supply selector 21 to the b side and setting the anode power supply wiring 20 to high impedance. Note that “non-display” refers to a state in which no current flows through the EL element 15 or a small state even when it flows.

  The display area 112 shows a pixel row or a group of pixel rows in which the power supply selector 21 is set to the a side, the potential of the anode power supply wiring 20 is changed to Vdd_H, and current is supplied to the EL element 15.

  The non-display area 113 and the display area 112 are scanned in the vertical direction of the display screen 22 in synchronization with the frame period or the horizontal synchronization signal.

(10-1) Problem In the display state of FIG. 13A, one display area 112 moves downward from the top of the screen. When the frame rate is low, it is visually recognized that the display area 112 moves. In particular, it becomes easier to recognize when the eyelid is closed or when the face is moved up and down.

(10-2) First Solution To solve this problem, as shown in FIGS. 13B and 13C, the display area 112 is divided into a plurality of parts.

  Note that the divided display areas 112 do not have to be equal (equally divided). For example, the display area is divided into four areas, the divided display area 112a is area 1, the divided display area 112b is area 2, and the divided display area 112c is area 1 and is divided. The area 4 may be 112d.

  In the first to fourth solving means, the area of the display region 112 is described as being divided for easy understanding. However, dividing the area means dividing a period (time). Therefore, in FIG. 1, the output Vdd_H period of the power supply circuit 23 is divided. Therefore, dividing the area is synonymous or similar to dividing the period (time).

(10-3) Second Solution The control is performed so that the area of the display area 112 in several frames or several fields (hereinafter collectively referred to as “frames”) is averaged to a target size. Also good. For example, when the area of the display area 112 occupying the display screen 22 is 1/10, the area of the display area 112 is 1/10 in the first frame, and the area of the display area 112 is 1/20 in the second frame. In the third frame, the area of the display area 112 is 1/20, and in the fourth frame, the area of the display area 112 is 1/5, and 1/10 of the predetermined display area (display luminance) is obtained in the above four frames. The driving method is exemplified.

  Note that one frame or one field in the present embodiment is synonymous with an image rewriting cycle of the pixels 16 or a cycle in which the display screen 22 is scanned from top to bottom (from bottom to top).

(10-4) Third Solution Further, each of R, G, and B may be driven so that the averages of the L periods are equal in several frames.

  However, the number of frames is preferably 4 frames or less. This is because flicker may occur depending on the display image.

(10-5) Fourth Solution The R, G, and B may be driven so that the average of the L periods is different in several frames and an appropriate white balance is obtained.

  This driving method is particularly effective when the RGB luminous efficiencies are different.

  Further, the division number K (K is the number by which the display area 112 is divided into a plurality of parts) may be different for RGB. In particular, since it is visually noticeable in G, it is effective in G to increase the number of divisions relative to RB.

(10-6) Effect As described above, screen flickering is reduced by dividing display area 112 into a plurality of parts. Therefore, no flicker occurs and a good image display can be realized. Although the division may be made finer, the moving image display performance decreases as the division is performed.

  In addition, the frame rate of image display can be reduced, and low power consumption can be realized. For example, in the case where the non-lighting areas 113 are integrated, flicker occurs when the frame rate is 45 Hz or less. However, when the non-lighting area 113 is divided into six or more, flicker does not occur up to 20 Hz or less.

(10-7) When Display Area 112 is Continuing FIGS. 13A1 to 13A3 are brightness adjustment methods when the display area 112 is continuous as shown in FIG.

  The display brightness of the display screen 22 in FIG. 13 (a1) is the brightest, the display brightness of the display screen 22 in FIG. 13 (a2) is the next brightest, and the display brightness of the display screen 22 in FIG. 13 (a3) is the darkest. The change from FIG. 13 (a1) to FIG. 13 (a3) (or vice versa) can be easily realized by the control of the power supply selector 21 as described above.

  At this time, it is not necessary to change the magnitude of the program current or the program voltage output from the source driver circuit 14. That is, it is possible to change the luminance of the display screen 22 without changing the video signal.

  In addition, the gamma characteristic of the screen does not change at all when the change from FIG. 13 (a1) to FIG. 13 (a3) occurs. Therefore, the contrast and gradation characteristics of the display image are maintained regardless of the brightness of the display screen 22. This is an effective feature of the present embodiment.

  In the conventional screen brightness adjustment, the gradation performance deteriorates when the brightness of the display screen 22 is low. That is, even when 64 gradation display can be realized during high brightness display, only half or less gradations can be displayed during low brightness display. Compared to this, the driving method of the present embodiment can realize the highest 64 gradation display without depending on the display brightness of the screen.

(10-8) Case where Display Area 112 is Dispersed FIGS. 13B1 to 13B3 are brightness adjustment methods when the display area 112 is dispersed as described with reference to FIG.

  The display brightness of the display screen 22 in FIG. 13 (b1) is the brightest, the display brightness of the display screen 22 in FIG. 13 (b2) is the next brightest, and the display brightness of the display screen 22 in FIG. 13 (b3) is the darkest. The change from FIG. 13 (b1) to FIG. 13 (b3) (or vice versa) can be easily realized by controlling the shift register circuit 61 of the gate driver circuit 12 as described above. If the display area 112 is dispersed as shown in FIG. 13B, flicker does not occur even at a low frame rate.

(10-9) Low Frame Rate Further, in order to prevent flicker from occurring even at a low frame rate, the display area 112 may be finely dispersed as shown in FIG. However, the display performance of moving images decreases. Therefore, the driving method shown in FIG. 13A is suitable for displaying a moving image. When a still image is displayed and low power consumption is desired, the driving method shown in FIG. 13C is suitable. The switching of the driving method from FIG. 13A to FIG. 13C can be easily realized by controlling the shift register.

(10-10) Modification Example In FIG. 13, the non-display areas 113 are configured at equal intervals, but the present invention is not limited to this. The display area 112 may be driven so that a half area of the display screen 22 is continuously used as the display area 112 and the remaining area is repeated at equal intervals as shown in FIG. .

(11) Application Example A display device according to the present embodiment using an EL display device that implements the driving method according to the present embodiment as a display display will be described.

(11-1) First Application Example FIG. 15 is a plan view of a mobile phone of an information terminal device which is an example of an EL display device.

  An antenna 141 and the like are attached to the housing 143. 142a is a switch key for changing the brightness of the display screen 22, 142b is a power on / off key, and 142c is a key for switching the operation frame rate of the gate driver circuit 12b. Reference numeral 145 denotes a photo sensor. The photo sensor 145 automatically adjusts the luminance of the display screen 22 by changing the duty ratio and the like according to the intensity of external light.

(11-2) Second Application Example FIG. 16 is a perspective view of a video camera.

  The video camera includes a photographing (imaging) lens unit 153 and a video camera body 143. The EL display panel of this embodiment is also used as the display monitor 144. The display screen 22 can freely adjust the angle at a fulcrum 151. When the display screen 22 is not used, it is stored in the storage unit 153.

(11-3) Third Application Example The EL display panel or EL display device of this embodiment can be applied not only to a video camera but also to an electronic camera as shown in FIG.

  That is, the EL display device of this embodiment is used as the monitor 22 attached to the camera body 161. In addition to the shutter 163, switches 142a and 142c are attached to the camera body 161.

(Second Embodiment)
An EL display device according to a second embodiment will be described with reference to FIG. FIG. 18 is a schematic circuit diagram showing the EL display device according to this embodiment.

  The difference from the first embodiment is that the pixel circuit is configured using a P-channel transistor in the present embodiment, whereas the pixel circuit is configured using an N-channel transistor in the first embodiment. That is to make up. The pixel circuit in FIG. 18 can perform the threshold voltage correction operation, the mobility correction operation, and the bootstrap operation similarly to the pixel circuit shown in FIG.

(Example of change)
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

  In each of the above embodiments, pixel rows are selected one by one, and video signal writing and cancellation are performed. However, the present invention is not limited to this.

  For example, a plurality of pixel rows may be selected simultaneously, and video signal writing and cancellation may be performed. FIG. 14 shows the embodiment. In FIG. 14, adjacent pixel rows are connected to different source signal lines 18 (18a, 18b) so that two pixel rows can be selected simultaneously.

It is explanatory drawing of the pixel structure of the EL display apparatus of the 1st Embodiment of this invention. It is a block diagram which shows the whole structure of EL display apparatus. It is a timing chart regarding operation | movement description. 6 is a circuit diagram illustrating an operation during a light emission period B. FIG. 6 is a circuit diagram illustrating an operation in a period C. FIG. 6 is a circuit diagram illustrating an operation in a period D. FIG. 6 is a circuit diagram illustrating an operation during a threshold correction period E. FIG. 6 is a circuit diagram illustrating an operation during a sampling period F. FIG. 6 is a circuit diagram illustrating an operation during a light emission period G. FIG. FIG. 6 is a circuit diagram for explaining an operation during an extinction period H. It is a block diagram of a power supply selector and a power supply circuit. It is explanatory drawing of the drive method which shows a program pixel row. It is explanatory drawing of a duty drive method. It is explanatory drawing of the 1st application example. It is explanatory drawing of the 2nd application example. It is explanatory drawing of the 3rd application example. It is explanatory drawing of the 3rd application example. It is explanatory drawing of the pixel structure of the EL display apparatus of 2nd Embodiment.

Explanation of symbols

11 Transistor 12 Gate Driver Circuit 14 Source Driver Circuit 15 EL Element 16 Pixel 17 Gate Signal Line 18 Source Signal Line 19 Capacitor 20 Anode Voltage Wiring 21 Power Supply Selector 22 Display Screen 23 Power Supply Circuit

Claims (4)

In an EL display device having a display screen in which a plurality of pixels having EL elements are arranged in a matrix,
Each of the pixels is
A driving transistor having a source terminal connected to the EL element and a drain terminal connected to an anode voltage wiring;
A switching transistor connected to a gate terminal of the driving transistor and applying a video signal from a source signal line;
A capacitor connected to the gate terminal and the source terminal of the driving transistor;
Have
A power supply circuit for supplying a drive control voltage to the anode voltage wiring;
Arranged between the anode voltage wiring and the power supply circuit, the drive control voltage can be switched to a high impedance state, and a display area is generated on the display screen when switched to the drive control voltage, A power supply selector that generates a non-display area on the display screen when switched to the high-impedance state, suppresses a current flowing through the EL element, and performs duty drive;
EL display device having The drive control voltage includes a drive voltage for causing the EL element to emit light and the cancel voltage,
Generating the display area on the display screen when the power supply circuit switches the drive control voltage from the cancel voltage to the drive voltage;
The EL display device according to claim 1. A source driver circuit for supplying the video signal to the source signal line,
After supplying the reference potential to the source signal line after the switching transistor is turned on, the voltage applied to the drain terminal of the driving transistor is switched between a cancel voltage and a driving voltage, A voltage corresponding to the threshold voltage of the driving transistor is held in the capacitor.
The EL display device according to claim 1. When the signal potential is held in the capacitor, the power supply circuit changes the output to the cancel voltage and the drive voltage,
Changing the potential of the drain terminal of the driving transistor to the cancellation voltage and the driving voltage;
A gate driver circuit for sending a gate signal to the switch transistor, the switch transistor is turned off, and the gate terminal of the drive transistor is electrically disconnected from the source signal line;
The EL display device according to claim 1.