CN100454373C - active matrix display device - Google Patents

Abstract

The present invention provides an active matrix display device, which reduces display unevenness and animation afterimage time, thereby improving display quality. The active matrix display device of the present invention is synchronized with the falling of the vertical start pulse signal STV, and the control circuit 303 outputs the precharge pulse signal PCG1 and the storage capacitor control pulse signal SC1 successively. Focusing on the pixels in the first row, the precharge TFT 220 is turned on in response to the precharge pulse signal PCG1. In this way, the source and gate of the driving TFT 214 are short-circuited, the gate potential of the driving TFT 214 becomes the positive power supply potential PVdd which is the same as the source potential, and the driving TFT 214 is cut off. Thereafter, the holding capacitor control pulse signal SC1 rises to a high level, and the gate potential of the driving TFT 214 rises due to the capacitive coupling effect of the holding capacitor 218 . Thereby, the electrical characteristics of the driving TFT 214 are initialized.

Description

active matrix display device

technical field

The present invention relates to an active matrix display device having a light emitting element such as an electromechanical light emitting element.

Background technique

In recent years, display devices used to replace cathode ray tubes (CRTs) and liquid crystal displays (LCDs) have developed organic electroluminescent devices (Organic ElectroLuminescent Devices, hereinafter referred to as "organic electroluminescent devices"). Excite light display device. In particular, an active matrix organic electroluminescent display device having a thin film transistor (Thin Film Transistor, hereinafter referred to as "TFT") as a switching element for driving an organic electroluminescent element has been developed.

Hereinafter, an active matrix organic electroluminescent display device will be described with reference to the drawings. FIG. 9 is an equivalent circuit diagram of an organic electroluminescence display device. FIG. 9 shows only one pixel 210 among a plurality of pixels arranged in a matrix on the display panel. An N-channel type TFT 213 for pixel selection is disposed near the intersection of the pixel selection signal line 211 extending in the row direction and the display signal line 212 extending in the column direction. The gate of the TFT 213 for pixel selection is connected to the pixel selection signal line 211 , and the drain is connected to the display signal line 212 . A high-level pixel selection signal G output from the vertical drive circuit 301 is applied to the pixel selection signal line 211 , and the pixel selection TFT 213 is turned on correspondingly. The display signal D is output from the horizontal drive circuit 302 to the display signal line 212 .

The source of the TFT 213 for pixel selection is connected to the gate of the P-channel type TFT 214 for driving. The source of the driving TFT 214 is connected to a power supply line 215 that supplies a positive power supply potential PVdd. The drain of the driving TFT 214 is connected to the anode of the organic electroluminescence element 216 . The cathode of the organic electroluminescent element 216 is supplied with a negative power supply potential CV.

In addition, a storage capacitor 218 is connected between the gate of the driving TFT 214 and the storage capacitor line 217 . The hold capacitor line 217 is fixed at a constant potential. The holding capacitor 218 holds the display signal D applied to the gate of the driving TFT 214 through the pixel selecting TFT 213 for one vertical period.

Next, the operation of the above-mentioned organic electroluminescent display device will be described. When a high-level pixel selection signal G is applied to the pixel selection signal line 211 in one horizontal period, the pixel selection TFT 213 is turned on. Then, the display signal D output from the display signal line 212 is applied to the gate of the driving TFT 214 through the pixel selecting TFT 213 and held by the holding capacitor 218 . That is, the display signal D is written into the pixel 210 .

Thereafter, the conductance (conductance) of the driving TFT 214 is changed in response to the display signal D applied to the gate of the driving TFT 214, and when the driving TFT 214 is turned on, a current corresponding to the conductance is supplied to the active state through the driving TFT 214. The electromechanical light emitting element 216 makes the organic electroluminescent element 216 emit light with a brightness corresponding to the current. On the other hand, when the driving TFT 214 is made non-conductive in response to the display signal D supplied to the gate, since no current flows through the driving TFT 214 , the organic electroluminescence element 216 is turned off. By performing the above operation on all rows of pixels 210 in one vertical period, a desired image can be displayed on the entire display panel.

However, in the above-mentioned organic electroluminescence display device, there will be problems of uneven brightness of the display panel and image sticking. Therefore, as disclosed in Patent Document 1, the light-emitting period of the organic electroluminescent element 216 is controlled by using the scanning series signal (such as the above-mentioned pixel selection signal G) of the vertical driving circuit 301, thereby reducing uneven brightness and image sticking time. If the display area of the display panel is composed of pixels in n rows and m columns, for example, when half of a vertical period is set as a light-emitting period, the pixel selection signal G connected to the pixel selection signal line 211 of the n/2th row rises to a high level. The flat timing is synchronized so that the organic electroluminescent element 216 is turned off.

[Patent Document 1] Japanese Patent Laid-Open No. 2002-175035.

Contents of the invention

(problem to be solved by the invention)

However, the light emission period control method of Patent Document 1 is hardware light emission period setting, and once the light emission period is set, the light emission period cannot be changed unless the physical wiring connection is changed. To change the connection of the wiring, it is necessary to change the shielding of the wiring, thus causing an increase in the shielding cost, increasing the manufacturing cost of remanufacturing such a display panel, and increasing problems during the manufacturing.

(means used to solve a problem)

The active matrix display device of the present invention is characterized in that it has a plurality of pixels arranged in a matrix; each pixel has: a pixel selection transistor; a light emitting element; A driving transistor for driving the light-emitting element; in addition, the display device also has a control circuit to control the conduction and non-conduction of the above-mentioned driving transistor in response to the vertical start pulse signal used to start the vertical scanning.

(effect of invention)

According to the present invention, in the active matrix display device, the light-emitting period and the extinguishing period of the light-emitting element can be freely adjusted by using the vertical start pulse signal. Through this adjustment, the display unevenness and animation afterimage of the display panel can be reduced, and the display quality can be improved. .

Description of drawings

FIG. 1 shows an equivalent circuit diagram of an organic electroluminescence display device according to a first embodiment of the present invention.

FIG. 2 illustrates a timing chart of a driving method of an organic electroluminescence display device according to a first embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of a display device according to a second embodiment of the present invention.

FIG. 4 illustrates a timing diagram of a driving method of a display device according to a second embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of an organic electroluminescent display device according to a third embodiment of the present invention.

FIG. 6 illustrates a timing chart of a driving method of an organic electroluminescent display device according to a third embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram of a display device according to a fourth embodiment of the present invention.

FIG. 8 illustrates a timing diagram of a driving method of a display device according to a fourth embodiment of the present invention.

FIG. 9 is an equivalent circuit diagram of a conventional organic electroluminescent display device.

FIG. 10 is an equivalent circuit diagram of a display device according to a fifth embodiment of the present invention.

FIG. 11 illustrates a timing chart of a driving method of a display device according to a fifth embodiment of the present invention.

Description of main component symbols:

210, 210A, 210B pixels

211 pixel selection signal line

212 Display signal line 213 TFT for pixel selection

214 TFT for driving 215 Power cord

216 Organic electroluminescence element

217 Holding Capacitor Line 218 Holding Capacitor

220, 225 TFT for pre-charging

221 Precharge signal line 301 Vertical drive circuit

302 Horizontal drive circuit 303 Control circuit

304 Pulse counter 305, 306, 307, 308 control circuit

CKH1, CKH2 horizontal frequency

CKV1, CKV2 vertical frequency

CV Negative power supply potential D Display signal

ENB Enable signal G, G1, G2, G3 Pixel selection signal

PCG1, PCG2 Precharge pulse signal

PVdd Positive power supply potential

SC1, SC2 holding capacitor control pulse signal

STH level start pulse signal

STV vertical start pulse signal

Detailed ways

An active matrix organic electroluminescent display device according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an equivalent circuit diagram of the organic electroluminescence display device. FIG. 1 shows only pixels 210A in a first row and pixels 210B in a second row among a plurality of pixels arranged in a matrix on a display panel. The pixels 210A, 210B are adjacent to each other in the column direction. In addition, in FIG. 1, the same components as those in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, although TFT213 for pixel selection and TFT220 for precharging are N-channel type, and TFT214 for driving is P-channel type, it demonstrates that this invention is not limited to these channel types.

In the pixel 210A, a precharge TFT 220 is connected between the source and the gate of the drive TFT 214 . The gate of the precharge TFT 220 is connected to the precharge signal line 221 , and since the precharge signal line 221 is supplied with the precharge pulse signal PCG1 , the precharge TFT 220 switches according to the precharge pulse signal PCG1 . When the precharge TFT 220 is turned on, the source and gate of the drive TFT 214 are short-circuited. Thereby, both the source potential and the gate potential of the driving TFT 214 are set to the positive power supply potential PVdd, so the driving TFT 214 becomes non-conductive. When the precharge TFT 220 is made non-conductive, the source and gate of the drive TFT 214 are electrically insulated. Note that a fixed potential is not supplied to the storage capacity line 217 , but a storage capacity control pulse signal SC1 which is at a high level for a predetermined period described later is supplied.

Although the pixel 210 also has the same configuration, a precharge pulse signal PCG2 is supplied to the precharge signal line 221 , and a storage capacitance control pulse signal SC2 is supplied to the storage capacitance line 217 .

The vertical drive circuit 301 shifts a vertical start pulse signal STV serving as a reference signal for starting vertical scanning in synchronization with complementary vertical frequencies CKV1 and CKV2 to generate pixel selection signals G1 and G2 . The pixel selection signal G1 is applied to the gate of the pixel selection TFT 213 of the pixel 210A through the pixel selection signal line 211 , and the pixel selection signal G2 is applied to the gate of the pixel selection TFT 213 of the pixel 210B through the pixel selection signal line 211 . The enable signal ENB is a signal for controlling the timing at which the pixel selection signal G1 is output to the pixel selection signal line 211 , and is used for preventing the pixel selection signals G1 and G2 from overlapping.

The horizontal driving circuit 302 shifts the horizontal start pulse signal STH in synchronization with the complementary horizontal frequencies CKH1 and CKH2 to generate a horizontal scanning signal. Then, the horizontal driving circuit 302 outputs the display signal D to the display signal line 212 in synchronization with the horizontal scanning signal.

The control circuit 303 is a circuit that generates the precharge pulse signals PCG1 and PCG2 and the storage capacitor control pulse signals SC1 and SC2 in synchronization with the falling of the vertical start pulse signal STV. In FIG. 1 , the control circuit 303 is disposed outside the vertical driving circuit 301 , but it may also be disposed inside the vertical driving circuit 301 .

Hereinafter, a driving method of the above-mentioned organic electroluminescent display device will be described with reference to the accompanying drawings. FIG. 2 illustrates a timing chart of the driving method of the display device of the present embodiment. In synchronization with the rise of the vertical start pulse signal STV, the pixel selection signals G1 , G2 , and G3 from the vertical drive circuit 301 are pulsed successively.

Focusing on the pixels in the first row, corresponding to the high-level pixel selection signal G1, the pixel selection TFT 213 of the pixel 210A in the first row is turned on for a horizontal period, during which the display signal D is sent from the horizontal drive circuit 302 is output to the display signal line 212 , applied to the gate of the driving TFT 214 through the pixel selecting TFT 213 , and held by the storage capacitor 218 . That is, the display signal D is written into the pixel 210A. Afterwards, when the display signal D applied to the gate of the driving TFT 214 makes the driving TFT 214 in a conductive state, a current corresponding to the conductance is supplied to the organic electroluminescent element 216 through the driving TFT 214, and the organic electroluminescent element 216 is turned on. 216 emits light at a brightness corresponding to this current.

When the pixel selection signal G1 is returned to low level at the end of one horizontal period, although the pixel selection TFT 213 is non-conductive, the display signal D is held by the storage capacitor 218, so the light emitting period of the organic electroluminescent element 216 continues. go down. That is, the pixels in the first row start the light emission period in response to the rise of the pixel selection signal G1, the pixels in the second row start the light emission period in response to the rise of the pixel selection signal G2, and the pixels in the third row start the light emission period in response to the rise of the pixel selection signal G3. And so that the glow period begins.

Thereafter, in synchronization with the falling of the vertical start pulse signal STV, the control circuit 303 outputs precharge pulse signals PCG1 , PCG2 and storage capacitor control pulse signals SC1 , SC2 successively. Focusing on the pixels in the first row, the precharge TFT 220 is turned on in response to the high-level precharge pulse signal PCG1 . Then, the source and gate of the driving TFT 214 are short-circuited, the gate potential of the driving TFT 214 becomes the same as the source potential and becomes the positive power supply potential PVdd, and the driving TFT 214 becomes non-conductive. Thereby, since the organic electroluminescent element 216 is turned off, the light-emitting period ends, and the extinguishing period starts, and the extinguishing period lasts until the pixel selection signal G1 rises to a high level in the next vertical period.

Thereafter, when precharge pulse signal PCG1 becomes low level, precharge TFT 220 becomes non-conductive, and the source and gate of drive TFT 214 become insulated. Afterwards or at the same time, the holding capacitor control pulse signal SC1 rises to a high level. Thus, due to the capacitive coupling effect of the storage capacitor 218, the gate potential of the driving TFT 214 rises corresponding to the voltage change ΔV (for example, about 10V) of the storage capacitor control pulse signal SC1 from low level to high level.

Thereby, the gate potential of the driving TFT 214 becomes higher than the source potential. If the carriers (holes) are collected at the gate insulating film of the driving TFT 214 due to the writing of the display signal D last time, these carriers (holes) will flow from the gate to the source or drain. The electric field of the gate becomes a tunnel current, which is pulled from the gate insulating film to the source or drain. Thereby, the electrical characteristics of the driving TFT 214 are initialized. Thus, when the display signal D is written into the pixel in the next frame period, a current of an appropriate current value corresponding to the display signal D can flow through the driving TFT 214 .

The same applies to the pixels in the second row, and the light emission period starts from the rise of the pixel selection signal G2. Then, after the precharge pulse signal PCG1 of the first row changes to low level, the precharge pulse signal PCG2 of the second row rises, and the precharge TFT 220 is turned on. Thereafter, when precharge pulse signal PCG2 changes to low level, precharge TFT 220 becomes non-conductive, and the source and gate of drive TFT 214 become insulated. Afterwards or at the same time, the holding capacitor control pulse signal SC2 rises to a high level. Then, due to the capacitive coupling effect of the storage capacitor 218 , the gate potential of the driving TFT 214 rises corresponding to the voltage change ΔV from the low level to the high level of the storage capacitance control pulse signal SC2 . Thereby, the electrical characteristics of the driving TFT 214 are initialized. Pixels in the third and subsequent rows perform the same operation.

According to this embodiment, by controlling the pulse width of the vertical start pulse signal STV, the light emitting period and the extinguishing period of the organic electroluminescence element 216 of each pixel can be freely adjusted without changing the mask as in the past. Through this adjustment, the display unevenness of the display panel and the afterimage time of the animation can be reduced, thereby improving the animation display quality. In addition, by supplying the high-level storage capacitance control pulse signal SC1 to the storage capacitance line 217, the initialization of the electrical characteristics of the driving TFT 214 can be optimized, and the image sticking phenomenon of the display panel can be further suppressed. .

An active matrix organic electroluminescent display device according to a second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows an equivalent circuit diagram of the organic electroluminescence display device. In FIG. 3 , only pixels 210A in the first row and pixels 210B in the second row are displayed among a plurality of pixels arranged in a matrix on the display panel. The pixels 210A, 210B are adjacent to each other in the row direction. In addition, in FIG. 3, the same components as those in FIG. 9 are given the same reference numerals and description thereof will be omitted.

In the first embodiment, the pulse width of the vertical start pulse signal STV is used to adjust the length of the light-emitting period and the length of the extinguishing period of the organic electroluminescent element 216 of each pixel, and the electrical characteristics of the driving TFT 214 are adjusted during the extinguishing period. initialization. In contrast, in this embodiment, two vertical start pulse signals STV are input within one vertical period, thereby synchronizing with the second vertical start pulse signal STV to generate the above-mentioned precharge pulse signals PCG1, PCG2 and the aforementioned The holding capacitor control pulse signals SC1 and SC2 are used to adjust the light-emitting period and the extinguishing period.

In FIG. 3, a pulse counter 304 for counting the number of pulses of the vertical start pulse signal STV is provided. When the pulse counter 304 counts the two vertical start pulse signals STV, the control circuit 305 generates the precharge pulse signals PCG1 , PCG2 and the holding capacitor control pulse signals SC1 , SC2 according to the count value. In FIG. 3 , the pulse counter 304 and the control circuit 305 are arranged outside the vertical driving circuit 301 , but they may also be arranged inside the vertical driving circuit 301 .

A driving method of the organic electroluminescent display device of the second embodiment will be described below with reference to the drawings. FIG. 4 illustrates a timing chart of the driving method of the display device of the present embodiment. Synchronized with the rise of the first vertical start pulse signal STV, the pixel selection signals G1, G2, and G3 from the vertical driving circuit 301 are pulsed out successively.

Thus, like the first embodiment, the display signal D is sequentially written to the pixels in the first row, the second row, and the third row. Afterwards, when the second vertical start pulse signal STV rises to a high level, the control circuit 305 outputs the precharge pulse signal PCG1 for the first row. In response to this precharge pulse signal PCG1, the precharge TFT 220 is turned on. Subsequent operations are the same as those in the first embodiment. When the precharge pulse signal PCG1 changes to a low level, the holding capacitor control pulse signal SC1 rises to a high level. Thereafter, during the extinguishing period of the organic electroluminescent element 216 , the electrical characteristics of the driving TFT 214 are initialized.

The same applies to the pixels in the second row. When the precharge pulse signal PCG1 in the first row changes to low level, the precharge pulse signal PCG2 in the second row rises. Once the precharge pulse signal PCG2 changes to a low level, the holding capacitor control pulse signal SC2 rises to a high level. Thereafter, the electrical characteristics of the driving TFT 214 are initialized during the extinguishing period of the organic electroluminescence element 216 . The remaining pixels on and after the third row also perform the same operation.

In addition, in this embodiment, two vertical start pulse signals STV are input, but three or more vertical start pulse signals STV may be input. The length of the off period can be adjusted by counting the number of pulses of the vertical start pulse signal STV by the pulse counter 304 .

An active matrix organic electroluminescence display device according to a third embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows an equivalent circuit diagram of this organic electroluminescence display device. In the second embodiment, the precharge TFT 220 for making the driving TFT 214 non-conductive is provided, but in the present embodiment, the precharge TFT 220 and the precharge signal line 221 are omitted. Furthermore, like the second embodiment, a pulse counter 304 that counts the number of pulses of the vertical start pulse signal STV is provided. Once the pulse counter 304 counts the two vertical start pulse signals STV, the control circuit 306 generates the holding capacitor control pulse signals SC1 and SC2 according to the count value. That is, in this embodiment, the storage capacitance control pulse signals SC1 and SC2 are converted to a high level, thereby making the driving TFT 214 non-conductive.

A driving method of the organic electroluminescent display device of the third embodiment will be described below with reference to the drawings. FIG. 6 illustrates a timing chart of the driving method of the display device of the present embodiment. Synchronized with the rise of the first vertical start pulse signal STV, the pixel selection signals G1, G2, and G3 from the vertical driving circuit 301 are pulsed out successively.

Corresponding to the pixel selection signals G1 , G2 , G3 , the display signal D is sequentially written into the pixels in the first row, the second row, and the third row, and the light-emitting period of each row starts. After that, when the second vertical start pulse signal STV rises to a high level, the storage capacitance control pulse signal SC1 of the first row output from the control circuit 305 rises to a high level. Thereby, due to the capacitive coupling effect of the storage capacitor 218 , the gate potential of the driving TFT 214 rises corresponding to the voltage change ΔV of the storage capacitor control pulse signal SC1 from low level to high level. When the voltage change amount ΔV is large, the P-channel type driving TFT 214 becomes non-conductive, and the extinguishing period of the organic electroluminescent element 216 starts. Specifically, when the relationship of Vs-Vg<Vt is established, the driving TFT 214 becomes non-conductive. Vs is the source potential of the driving TFT 214 and is the positive power supply potential PVdd. Vg is a gate potential raised in response to a voltage change amount ΔV, and Vt is an absolute value of a threshold voltage of the driving TFT 214 .

Afterwards, after the enable signal ENB generated at the start of the next vertical period rises for a predetermined delay time, the holding capacitor control pulse signal SC1 changes from high level to low level to end the off period.

The same is true for the pixels in the second row. After the storage capacitance control pulse signal SC1 of the first row rises to a high level, the storage capacitance control pulse signal SC2 of the second row rises to a high level, so that the light-emitting period of the pixels in the second row ends. And start to go off period. In addition, the same is true for the pixels in the third row. After the storage capacitance control pulse signal SC2 of the second row rises to a high level, the storage capacitance control pulse signal SC3 of the third row rises to a high level, so that the light-emitting period of the pixels in the third row ends, while the beginning goes off period. The remaining pixels after the fourth row also perform the same operation. In addition, the configuration in which the precharge TFT 220 and the precharge signal line 221 are removed as in the present embodiment can also be applied to the first embodiment.

An active matrix organic electroluminescence display device according to a fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 7 shows an equivalent circuit diagram of this organic electroluminescence display device. In the second embodiment, the driving TFT 214 is a P-channel type, but in this embodiment, the driving TFT 214 is an N-channel type. Accompanying this change, the connection point of TFT 225 for precharging is also changed as shown in FIG. 7 .

A driving method of the organic electroluminescent display device of the fourth embodiment will be described below with reference to the drawings. FIG. 8 illustrates a timing chart of the driving method of the display device of this embodiment. Synchronized with the rise of the first vertical start pulse signal STV, the pixel selection signals G1, G2, and G3 from the vertical driving circuit 301 are pulsed out successively.

Thus, similar to the second embodiment, the display signal D is sequentially written into the pixels in the first row, the second row, and the third row, and the light-emitting period of each row starts. Afterwards, when the second vertical start pulse signal STV rises to a high level, the control circuit 307 outputs a precharge pulse signal PCG1 for the first row.

In response to the precharge pulse signal PCG1, the precharge TFT 225 is turned on. Then, the source and gate of the driving TFT 214 are short-circuited, the gate potential and the source potential of the driving TFT 214 become the same potential, and the driving TFT 214 becomes non-conductive. Thereby, since the organic electroluminescent element 216 is turned off, the light emitting period ends and the extinguishing period starts, and the extinguishing period lasts until the pixel selection signal G1 rises to a high level in the next vertical period. In addition, as described above, the N-channel configuration of the driving TFT 214 can also be applied to the first embodiment.

An active matrix organic electroluminescent display device according to a fifth embodiment of the present invention will be described below with reference to the drawings. FIG. 10 shows an equivalent circuit diagram of this organic electroluminescent display device. This embodiment is the same as the third embodiment except that the precharge TFT 220 and the precharge signal line 221 are omitted. The difference from the third embodiment is that the pulse counter 304 that counts the number of pulses of the vertical start pulse signal STV is not provided. Afterwards, the control circuit 308 generates the holding capacitor control pulse signals SC1 and SC2 synchronously with the falling of the vertical start pulse signal STV. By switching these storage capacitance control pulse signals SC1 and SC2 to high level, the driving TFT 214 is rendered non-conductive, and the off period starts.

A driving method of the organic electroluminescent display device of the fifth embodiment will be described below with reference to the drawings. FIG. 11 illustrates a timing chart of the driving method of the display device of this embodiment. Synchronized with the rising of the first vertical start pulse signal STV to the high level, the pixel selection signals G1 , G2 , G3 from the vertical driving circuit 301 are pulsed out successively.

Corresponding to the pixel selection signals G1 , G2 , G3 , the display signal D is sequentially written into the pixels in the first row, the second row, and the third row, and the light-emitting period of each row starts. Thereafter, when the vertical start pulse signal STV falls to a low level, the storage capacity control pulse signal SC1 of the first row output from the control circuit 308 rises to a high level. Thereby, due to the capacitive coupling effect of the storage capacitor 218 , the gate potential of the driving TFT 214 rises corresponding to the voltage change ΔV of the storage capacitor control pulse signal SC1 from low level to high level. When this voltage change amount ΔV is large, the P-channel type driving TFT 214 becomes non-conductive, and the light-off period of the organic electroluminescence element 216 starts. Specifically, when the relationship of Vs-Vg<Vt is established, the driving TFT 214 becomes non-conductive. Vs is the source potential of the driving TFT 214 and is the positive power supply potential PVdd. Vg is a gate potential raised in response to a voltage change amount ΔV, and Vt is an absolute value of a threshold voltage of the driving TFT 214 . Thereafter, after the enable signal ENB generated at the start of the next horizontal period rises for a predetermined delay time, the holding capacity control pulse signal SC1 changes from high level to low level to end the extinguishing period.

The same is true for the pixels in the second row. After the storage capacitance control pulse signal SC1 of the first row rises to a high level, the storage capacitance control pulse signal SC2 of the second row rises to a high level, so that the light-emitting period of the pixels in the second row ends and Start off period. In addition, the same is true for the pixels in the third row. After the storage capacitance control pulse signal SC2 of the second row rises to a high level, the storage capacitance control pulse signal SC3 of the third row rises to a high level to make the pixels of the third row emit light. The period ends and the period starts to go off. The remaining pixels after the fourth row also perform the same operation.

In addition, the above-mentioned embodiments are described by taking the case where the display device is composed of voltage-driven pixel circuits as an example. Although the display signal D supplied to each pixel is a voltage signal, the present invention is also applicable to current-driven pixel circuits. circuit. In this case, the display signal D is a current signal.

According to the above embodiments, the light emitting period of the organic electroluminescent element 216 of each pixel can be freely adjusted by using the vertical start pulse signal STV. Through this adjustment, the display unevenness and afterimage time of the display panel can be reduced, and the animation display quality can be improved. In addition, since the most suitable light-emitting period can be found in the development stage of the display device, the development period and development cost can also be effectively shortened. Furthermore, since the user of the display panel can control the above-mentioned light-emitting period, the user can apply the display panel of the same specification to the application software suitable for the purpose. For example, in a display panel for a video camera that mainly displays animation, the light emission time can be shortened to improve the animation responsiveness, and in a display panel for a camera, the light emission time can be extended to prevent flicker.

Claims (9)

1. an active-matrix type display device is characterized in that, has to be configured to rectangular a plurality of pixels; Each pixel has: the pixel selection transistor; Light-emitting component; And corresponding shows signal of supplying with transistor driving transistor that described light-emitting component is driven by described pixel selection;

Display device also has control circuit, and it controls described driving with transistorized conducting and non-conduction to being applied to make vertical scanning begin the vertical initial pulse signal that carries out.

2. active-matrix type display device according to claim 1, wherein, the corresponding described vertical initial pulse signal of described control circuit is changed to second level from first level, and it is non-conduction that described driving is become with transistor, and described light-emitting component is extinguished.

3. active-matrix type display device according to claim 1, wherein, described control circuit connects the counter circuit that the number of described vertical initial pulse signal is counted, and when the count value of described counter circuit reaches predetermined number, it is non-conduction that described driving is become with transistor, and described light-emitting component is extinguished.

4. an active-matrix type display device is characterized in that, has to be configured to rectangular a plurality of pixels; Each pixel has: the pixel selection transistor; Light-emitting component; Corresponding shows signal of supplying with transistor by described pixel selection and to the driving that described light-emitting component drives transistor; Be connected described driving with transistorized grid and the maintenance electric capacity that keeps between the electric capacity line and described shows signal is kept; And corresponding precharge pulse signal and conducting and make described driving form the precharge transistor of short circuit with transistorized source electrode and grid;

Display device also has control circuit, and it makes vertical scanning begin the vertical initial pulse signal that carries out and export described precharge pulse signal being applied to, and makes described precharge use transistor in the scheduled period conducting.

5. active-matrix type display device according to claim 4, wherein, described control circuit described precharge with transistor through becoming after the described scheduled period when non-conduction, to keep the electric capacity control wave to output to described maintenance electric capacity line, and make described driving become non-conduction mode with transistor, described driving is changed with respect to source potential with transistorized grid potential.

6. according to claim 4 or 5 described active-matrix type display device, wherein, the corresponding described vertical initial pulse signal of described control circuit is changed to second level and exports described precharge pulse signal from first level.

7. according to claim 4 or 5 described active-matrix type display device, wherein, described control circuit connects the counter circuit that the number of described vertical initial pulse signal is counted, and when the count value of described counter circuit reaches predetermined number, described precharge pulse signal is exported.

8. an active-matrix type display device is characterized in that, has to be configured to rectangular a plurality of pixels; And each pixel has: the pixel selection transistor; Light-emitting component; Corresponding shows signal of supplying with transistor by described pixel selection and to the driving that described light-emitting component drives transistor; And be connected described driving with transistorized grid and the maintenance electric capacity that keeps between the electric capacity line and described shows signal is kept;

Display device also has control circuit, it is changed to second level and will keeps the electric capacity control wave to output to described maintenance electric capacity line from first level the vertical initial pulse signal that is applied to make vertical scanning begin to carry out, whereby, by making described driving become non-conduction mode, described driving is changed with respect to source potential with transistorized grid potential with transistor.

9. according to each the described active-matrix type display device in the claim 1,2,3,4,8, wherein, described light-emitting component is an organic electroluminescent element.

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