JP2005189383A - Display device, and method for driving display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption and further efficiently avoid influence from a neighboring pixel when setting gradation from setting of voltage to a capacitor provided between gate sources to a transistor driving by current a light emitting element by source follower circuit configuration by being applied to a self-luminous display device by current drive of, for instance, an organic EL display device concerning the display device and a method for driving the display device. <P>SOLUTION: The display device does not connect to a power source Vcc a transistor TR2 for a period setting a source for setting voltage between gate sources to reference voltage to the transistor TR2 driving by current the light emitting element 12 by source follower circuit configuration. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a display device and a display device driving method, and can be applied to a self-luminous display device driven by current, such as a display device using organic EL (Electro Luminescence). According to the present invention, a transistor that current-drives a light emitting element with a source follower circuit configuration is configured not to connect a power source to the transistor during a period in which the source is set to a reference voltage for setting a gate-source voltage. As a result, when the gradation is set by setting the voltage to the capacitor provided between the gate and the source for the transistor that drives the light emitting element with the source follower circuit configuration, the power consumption is reduced, and further, the adjacent pixel It is possible to effectively avoid the influence from.

  Conventionally, in organic EL display devices, various applications to display devices have been proposed, for example, in US Pat. No. 5,684,365 and JP-A-8-234683.

  That is, as shown in FIG. 5, in this type of display device 1, the display unit 2 has scanning lines SCN provided in a horizontal direction in units of lines with respect to pixels (PX) 3 arranged in a matrix. A signal line SIG is provided in the vertical direction for each column so as to be orthogonal to the scanning line SCN. For the display unit 2 formed in this way, the display device 1 drives the scanning lines SCN by the vertical drive circuit 4 to sequentially select the pixels 3 of the display unit 2 in line units, and this pixel 3 The gray level of each pixel 3 is set by driving the signal line SIG by the horizontal drive circuit 5 so as to correspond to the selection.

  For this reason, the vertical drive circuit 4 generates a write signal WS for sequentially instructing writing to each pixel 3 in units of lines by the write scan circuit (WSCN) 4A, and outputs the write signal WS to the scan line SCN. The setting of gradation in the pixel 3 is controlled. The horizontal drive circuit 5 generates a drive signal in accordance with the gradation data D1 indicating the gradation of each pixel 3, distributes this drive signal to each signal line SIG by the horizontal selector (HSEL) 5A, and outputs it. Thus, the display device 1 is configured to set the gradation of each pixel 3 in line units.

  In the organic EL display device, each pixel 3 driven in this manner includes an EL element based on an organic EL which is a self-luminous element driven by current, and a driving circuit (hereinafter referred to as a pixel driving circuit) for driving the EL element. , Referred to as a pixel circuit).

  In the display device thus formed, each pixel circuit is formed by an N-channel MOS type TFT (Thin Film Transistor), thereby applying an amorphous silicon process to form an EL element and a pixel circuit. It can be integrally formed on the glass substrate, and as a result, as shown in FIG. 6, it is conceivable to drive the EL element 12 with a source follower circuit configuration.

  That is, the display device 11 shown in FIG. 6 is formed in each pixel 3 so that the EL element 12 is current-driven by the transistor TR2 having a source follower circuit configuration in which the source is connected to the anode of the EL element 12. A signal level holding capacitor C1 is provided at the gate of TR2. Here, one end of the signal level holding capacitor C1 is connected to the gate of the transistor TR2, and the other end is connected to a reference voltage. In the example of FIG. 6, this reference voltage is set to the power supply voltage Vcc. In the display device 11, the signal level holding capacitor C1 is connected to the signal line SIG by the transistor TR1 that is turned on by the write signal WS output from the write scan 4A, whereby the signal line is moved in response to the write signal WS. The gate voltage Vg of the transistor TR2 is set according to the signal level of the drive signal output to SIG. As a result, the display device 11 drives the EL element 12 with the current according to the gate voltage Vg set in this way, and causes the EL element 12 of each pixel 3 to emit light with the gradation according to the gradation data D1. A desired image can be displayed.

  However, in the organic EL, as shown in FIG. 7, the current-voltage characteristics change in a direction in which current does not easily flow through use. 7 and 8, reference numeral L1 indicates an initial characteristic, and reference numeral L2 indicates a characteristic due to change over time. On the other hand, in the driving by the sofa follower circuit described above with reference to FIG. 6, the characteristic curve due to the load intersects the characteristic curve of the drain-source voltage Vds−source drain current Ids of the transistor TR2 as shown in FIG. The intersecting point becomes the operating point. Thereby, in the organic EL, when the voltage-current characteristic is changed, the current flowing through the EL element is reduced accordingly, and there is a problem that the luminance of each pixel is gradually lowered.

As one method for solving this problem, a method of controlling the driving current of the EL element by setting the gradation by the gate-source voltage Vgs instead of the setting of the gradation by the gate voltage Vg can be considered. That is, the drain current Ids of the TFT is expressed by (1/2) × μ × (W / L) Cox (Vgs−Vth) ² , and thereby, the driving due to the change with time by setting the gradation by the gate-source voltage Vgs. A change in current can be prevented. Here, μ is the carrier mobility, W is the gate width, L is the gate length, Cox is the gate capacitance per unit area, and Vth is the threshold voltage.

  Therefore, as shown in FIG. 9 in comparison with FIG. 6, in each pixel 22, in place of the signal level holding capacitor C1 with respect to the gate of the transistor TR2, a signal level holding signal is provided between the gate and source of the transistor TR2. The capacitor C2 is disposed, and the signal level of the signal line SIG is set in the signal level holding capacitor C2. Further, the transistor TR3 which is turned on by the drive scan signal ds is connected to the source of the transistor TR2, and during the period in which the signal level of the signal line SIG is set in the signal level holding capacitor C2, the transistor TR3 causes the source potential of the transistor TR2 to be set. Is set to a constant potential. In FIG. 9, this constant potential is the ground potential. Corresponding to the configuration of the display unit 23 including such pixels 22, in the vertical drive circuit 24, in addition to the write scan circuit 24A, the drive scan signal is synchronized with the output of the write signal WS by the write scan circuit 24A. A drive scan circuit (DSCN) 24B for outputting ds is provided. The horizontal drive circuit 25 generates drive signals so as to correspond to these configurations.

  Actually, as shown in FIGS. 10A to 10D, when the transistor TR3 is turned on, the voltage gradually falls at the source potential of the transistor TR2. Accordingly, in this case, prior to setting the signal level of the signal line SIG to the capacitor C2 by the write signal WS, the transistor TR3 is turned on by the drive scan signal ds, and the source voltage Vs of the transistor TR2 (TR1) falls. After the potential becomes sufficiently constant, the transistor TR3 is turned on by the write signal WS, and the signal level Vin of the signal line SIG is set in the signal level holding capacitor C2. Thereafter, the write signal WS is lowered to turn off the transistor TR2, and then the drive scan signal ds is lowered. Thus, in this source follower circuit, the source voltage Vs rises and the EL element 12 starts to emit light by current driving according to the signal level Vin set in the signal level holding capacitor C2. 11A to 11D are connection diagrams showing settings of the transistors TR2 and TR3 corresponding to the periods T1 to T4 in FIG.

  Thus, if the drive current of the EL element 12 is controlled by the gradation setting by the gate-source voltage Vgs instead of the gradation setting by the gate voltage Vg, even if the characteristics of the EL element 12 change. The EL element 12 can be driven by a constant current determined by the gradation data D1, thereby effectively avoiding image quality deterioration due to changes over time.

  However, in the configuration shown in FIG. 9, the through current continues to flow from the power supply VCC to the transistors TR2 and TR3 during the periods T2, T3, and T4 during which the transistor TR3 is turned on by the drive scan signal ds. As a result, there is a problem that power consumption increases.

  Further, in such periods T2, T3, and T4, it is necessary to make the signal level S of the capacitor C2 for holding the signal level wider than the period T3 in which the signal level of the signal line SIG is set by the write signal WS. These periods T2, T3, and T4 overlap in the line, thereby causing the influence of adjacent pixels. Specifically, as shown in FIG. 12, in the wiring pattern for setting the source potential of the transistor TR3, the current of the pixel circuit in which the periods T2 to T4 overlap each other flows. For example, when these wiring patterns are grounded at the top and bottom of the display unit 23, the source potential of the transistor TR3 rises as the pixel on the center side of the screen in the vertical direction. As a result, the voltage across the holding capacitor C2 is lowered, and as shown in FIG. 13, shading occurs such that the brightness is lowered at the center side.

As shown in FIG. 14, when the periphery is set to an intermediate gradation and a low gradation area is formed at the center, a high gradation area is formed below the low gradation area. Vertical crosstalk occurs.
USP 5,684,365 JP-A-8-234683

  The present invention has been made in consideration of the above points, and in the case of setting a gradation by setting a voltage to a capacitor provided between a gate and a source for a transistor that drives a light emitting element with a source follower circuit configuration. In addition, an object of the present invention is to propose a display device and a display device driving method capable of reducing power consumption and effectively avoiding the influence from adjacent pixels.

  In order to solve this problem, in the first aspect of the present invention, a display device having a display unit in which pixels driven by current drive are arranged in a matrix and a drive circuit for driving the display unit to set the gradation of the pixel. Applying to the above, the pixel has a light emitting element, a transistor for driving the light emitting element by a source follower circuit configuration, a capacitor provided between the gate and source of the transistor, and a power supply switch for stopping the power supply to the transistor A circuit, a reference voltage switch circuit for connecting the source of the transistor to the reference voltage, and a signal line switch circuit for connecting the gate of the transistor to the signal line, the drive circuit is a power supply switch circuit, The signal level of the signal line is set in the capacitor by driving the switch circuit for the reference voltage and the switch circuit for the signal line. The transistor drives the light emitting element with the voltage between the gate and the source according to the signal level set in the sensor, and in setting the signal level of the signal line in the capacitor, the source of the transistor is connected to the reference voltage by the reference voltage switch circuit, The signal line switch circuit connects the transistor gate to the signal line and sets the signal line potential to the capacitor. At least during the period when the reference voltage switch circuit connects the transistor source to the reference voltage The power supply to the transistor is stopped by the switch circuit.

  According to a third aspect of the present invention, the pixel is applied to a display device having a display unit in which pixels driven by current are arranged in a matrix, and the pixel drives the light emitting element by a light emitting element and a source follower circuit configuration. And a capacitor provided between the gate and source of the transistor, a switch circuit for the reference voltage that connects the source of the transistor to the reference voltage, and sets the source potential of the transistor by the reference voltage, and a switch circuit for the reference voltage A signal line switch circuit for setting the signal level of the signal line in the capacitor by connecting the transistor gate to the signal line in a period in which the source of the transistor is connected to the reference voltage, and at least a reference voltage switch circuit During the period when the source of the transistor is connected to the reference voltage. So as to comprise a switch circuit for power supply to stop the power supply to the register.

  According to a fourth aspect of the present invention, the pixel is applied to a driving method of a display device having a display unit in which pixels driven by current drive are arranged in a matrix, and the pixel emits light by a light emitting element and a source follower circuit configuration. A transistor for driving the element, a capacitor provided between the gate and source of the transistor, a switch circuit for power supply for stopping supply of power to the transistor, and a switch circuit for reference voltage for connecting the source of the transistor to the reference voltage And a signal line switch circuit for connecting the gate of the transistor to the signal line, and the display device is driven by a power supply switch circuit, a reference voltage switch circuit, and a signal line switch circuit. To set the signal level of the signal line to the capacitor, and The light emitting element is driven by the transistor by the voltage between the sources, and in setting the signal level of the signal line in the capacitor, the source of the transistor is connected to the reference voltage by the switch circuit for the reference voltage, and the transistor by the switch circuit for the signal line Connect the gate of the transistor to the signal line, set the signal line potential to the capacitor, and supply power to the transistor with the power supply switch circuit for at least the period when the source of the transistor is connected to the reference voltage with the reference voltage switch circuit. Stop supplying.

  According to the configuration of the first aspect, the signal level of the signal line is set in the capacitor by driving the switch circuit for the power supply, the switch circuit for the reference voltage, and the switch circuit for the signal line, and the gate based on the signal level set in the capacitor The light emitting element is driven by the transistor by the voltage between the sources, and in setting the signal level of the signal line in the capacitor, the source of the transistor is connected to the reference voltage by the switch circuit for the reference voltage, and the transistor by the switch circuit for the signal line If the gate of the signal line is connected to the signal line and the potential of the signal line is set to the capacitor, even if the characteristic of the light emitting element changes in driving the light emitting element by the source follower circuit configuration, A change in driving current can be prevented. At this time, if the supply of power to the transistor is stopped by the power supply switch circuit at least while the source of the transistor is connected to the reference voltage by the reference voltage switch circuit, the reference voltage switch circuit causes the transistor source Even when this is connected to the reference voltage, current can be prevented from flowing in this transistor, and power consumption can be reduced accordingly. Further, since the current does not flow in this way, it is possible to prevent the reference voltage from changing in each part of the display unit, thereby effectively avoiding the influence from the adjacent pixels due to the change in the reference voltage, and in the vertical direction. Shading, crosstalk, etc. can be prevented.

  Thus, according to the configurations of claims 3 and 4, it is possible to provide a display device and a display device driving method capable of reducing power consumption and effectively avoiding the influence from adjacent pixels. it can.

  According to the present invention, when a gradation is set by setting a voltage to a capacitor provided between a gate and a source for a transistor that current-drives a light emitting element with a source follower circuit configuration, power consumption is reduced. Can effectively avoid the influence from adjacent pixels.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

(1) Configuration of Embodiment FIG. 2 is a block diagram showing a display device according to an embodiment of the present invention in comparison with FIG. 5 and FIG. In the display device 31, the display unit 32 includes current-driven pixels (PX) 33 arranged in a matrix, and three scanning lines SCN, SCN 1, SCN 2 are provided in the horizontal direction for each pixel 33. It is done. Further, a signal line SIG is provided in the vertical direction for each column so as to be orthogonal to these scanning lines SCN, SCN1, and SCN2. For the display unit 2 formed in this way, the display device 31 drives the scanning lines SCN, SCN1, and SCN2 by the vertical drive circuit 34, and the operation of the pixel circuit provided in the pixel 33 sequentially in line units. In addition, the gray level of each pixel 33 is set by driving the signal line SIG by the horizontal drive circuit 25 so as to correspond to the control of the pixel circuit.

  Therefore, the vertical drive circuit 34 generates a write signal WS for sequentially instructing writing to each pixel 33 in units of lines by the write scan circuit (WSCN) 34A, and outputs the write signal WS to the scan line SCN. The setting of gradation in the pixel 33 is controlled. In addition, a drive scan circuit (DSCN) 34B and a drive scan circuit (DSCN2) 34C for outputting drive scan signals ds1 and ds2 in synchronization with the output of the write signal WS by the write scan circuit 34A are provided.

  In the horizontal drive circuit 35, a drive signal is generated according to the gradation data D1 indicating the gradation of each pixel 33, and this drive signal is distributed to each signal line SIG by a horizontal selector (HSEL) 35A and output. It is made like that.

  FIG. 1 is a connection diagram showing each pixel 33 according to the display device 1 in comparison with FIG. In the pixel 33 according to the display device 1, the transistor TR4 is provided between the drain of the transistor TR2 and the power supply VCC in the configuration of the pixel 22 described with reference to FIG. In the display device 31, the supply of power to the transistor TR2 is stopped by the control of the transistor TR4, the light emission of the EL element 12 is stopped, and the gate-source voltage of the transistor TR2 is set by the signal line SIG. It is set so that no current flows through the transistor TR2. As a result, in this embodiment, power consumption is reduced, and various influences by pixels adjacent in the vertical direction are prevented. The transistors TR1 to TR4 constituting the pixel 33 are N-channel MOS type TFTs, and are integrally formed on the glass substrate together with the horizontal drive circuit 35 and the vertical drive circuit 34 by an amorphous process.

  That is, as shown in FIG. 3, in the vertical drive circuit 34, the write scan circuit 34A sequentially applies the write signal WS of the scanning line SCN in units of horizontal scanning period (1H) in one frame (1f) based on the gradation data D1. As shown in FIG. 3A, the transistor TR1 is turned on and the voltage Vin of the signal line SIG is set in the capacitor C2 provided at the gate source of the transistor TR2 in the pixel circuit of the corresponding line. To do. Thereby, in the display device 1, the transistor TR2 constitutes a transistor that drives the light emitting element 12 of the pixel 33 by the source follower circuit configuration, and the transistor TR1 connects the gate of the transistor TR2 to the signal line SIG to the capacitor C2. A switch circuit for a signal line for setting the signal level of the signal line SIG is configured.

  When the signal level of the signal line SIG is set in the capacitor C2 in this way, the vertical drive circuit 34 raises the drive scan signal ds1 from the drive scan circuit 34B (FIG. 3B), thereby the transistor TR2 Connect the source to the reference voltage. Here, in this display device 31, this reference potential is set to the ground potential. Thereby, in the display device 31, the signal level of the signal line SIG is reliably set in the capacitor C2 by a so-called boot slap circuit. Thereby, the transistor TR3 is configured to connect a source of the transistor TR2 to the reference voltage and constitute a reference voltage switch circuit for setting the source potential of the transistor TR2 by the reference voltage.

  The vertical drive circuit 34 raises the drive scan signal ds2 from the drive scan circuit 34B prior to the drive scan signal ds1 with respect to the write signal WS and the drive scan signal ds1 (FIG. 3C). During the period when the WS and drive scan signal ds1 rises, the transistor TR4 is set in the OFF state, and at least in the period when the source of the transistor TR2 is connected to the reference voltage by the reference voltage switch circuit. The drain of TR2 is disconnected from the power supply VCC.

  Accordingly, in each pixel circuit, in a predetermined period TA of one field, as shown in FIG. 4A, the transistors TR1 and TR3 are set in the off state, the transistor TR4 is set in the on state, and the capacitor C2 is connected. The EL element 12 is driven by the transistor TR2 by the current Ids corresponding to the gate-source voltage Vgs based on the set voltage Vin of the signal line SIG. In this state, when the drive scan signal ds2 is raised from the drive scan circuit 34C, the supply of the power supply VCC to the transistor TR2 is stopped as shown in FIG. 4B, and as shown by the period TB in FIG. The source voltage Vs of the transistor TR2 (FIG. 3D) gradually decreases due to the current flowing due to the current characteristics of the EL element 12, and as the source voltage Vs decreases, the gate voltage Vg of the transistor TR2 (FIG. 3). (E)) also gradually decreases, and when the source voltage Vs of the transistor TR2 becomes the threshold voltage Vth of the EL element 12, the decrease of the source voltage Vs and the gate voltage Vg is stopped.

  In this embodiment, when the source voltage Vs of the transistor TR2 substantially coincides with the threshold voltage Vth of the EL element 12, the drive scan signal ds1 is raised from the drive scan circuit 34B. As shown in FIG. 4C, the transistor TR3 is set to the on state, and the source voltage Vs of the transistor TR2 falls to the ground potential (period TC in FIG. 3).

  Further, the write signal WS is raised in the state where the source voltage Vs is set to the ground potential in this way, and as shown in FIG. 4D, the transistor TR1 is set to the on state, whereby the signal line SIG The potential Vin is set to the capacitor C2 (period TD in FIG. 3). After that, in the pixel 33, the write signal WS is raised and the transistor TR1 is turned off as shown in FIG. 4E (period TE in FIG. 3). Subsequently, the drive scan signal ds1, As shown in FIG. 4 (F), ds2 is sequentially raised, so that the original state is restored, and the transistor TR2 is operated by the power supply VCC to start driving the EL element 12.

  Thereby, in the transistor TR2, the gate voltage Vg and the source voltage Vs gradually rise while maintaining the difference between the gate-source voltage Vgs set in the capacitor C2, and the EL element 12 starts to emit light by this rise. Further, when the source voltage Vs rises to a voltage corresponding to the gate-source voltage Vgs set in the capacitor C2, the changes in the gate voltage Vg and the source voltage Vs are stopped, and in this state, the source voltage Vs corresponds to the gate-source voltage Vgs. The EL element 12 is driven by the drive current Ids.

(2) Operation of Embodiment In the above-described configuration (FIG. 2), the display device 31 sequentially selects the pixels 33 of the display unit 32 in units of lines by driving the scanning lines SCN, SCN1, and SCN2 by the vertical drive circuit 34. In addition, the signal level of the signal line SIG driven by the horizontal drive circuit 35 is set in each pixel 33 by the selection of the pixel 33. In the display device 31, each pixel 33 emits light according to the signal level set to each pixel 33, and a desired image is displayed.

  In the display device 31 (FIGS. 1, 3, and 4), in each pixel 33, a capacitor C2 is provided at the gate source of the transistor TR2 of the source follower circuit configuration for driving the EL element 12, and this is performed by a switch circuit by the transistor TR3. By connecting the gate of the transistor TR2 to the signal line SIG by the switch circuit by the transistor TR1 in a state where the source of the transistor TR2 is set to the ground potential which is a reference voltage, the signal level of the signal line SIG is set to each pixel 33. Set to

  Thus, in the display device 31, even when the characteristics of the EL element 12 change with time, the EL element 12 can be driven by current driving according to the gradation data D1. Further, such a driving can be realized by configuring the pixel circuit by an n-channel MOS type TFT transistor and driving the EL element 12 having a source follower circuit configuration by current driving.

  However, if no measures are taken, current continues to flow through the transistors TR2 and TR3 in each pixel 33, and power is consumed unnecessarily and power consumption increases accordingly. Further, the change in the reference voltage due to the current causes an influence by pixels adjacent in the vertical direction, and vertical shading and crosstalk occur.

  Therefore, in this embodiment, the transistor TR4 is provided between the drain of the transistor TR2 and the power supply VCC, and at least during the period in which the source of the transistor TR2 is connected to the reference voltage by the transistor TR3, the transistor TR4 The supply of power VCC to TR2 is stopped. As a result, current can be prevented from flowing from the power supply VCC via the transistors TR2 and TR3, and an increase in power consumption due to the continued flow of such current is prevented. Further, it is possible to prevent the influence of pixels adjacent in the vertical direction due to such a current, prevent vertical shading and crosstalk, and obtain a high uniformity image quality.

  In this embodiment, after the transistor TR4 stops supplying the power supply VCC to the transistor TR2, the source voltage Vs of the transistor TR2 sufficiently falls, and the potential Vin by the signal line SIG is set to the capacitor C2. The operation of TR1 and TR3 is switched, so that during the light emission and non-light emission periods of the EL element 12, it is executed by the on / off control of this transistor TR4, and the power consumption in this non-light emission period is remarkably reduced. Can do. Accordingly, the light emission and non-light emission periods can be controlled by simple control to reduce power consumption.

  In this way, when the source voltage Vs of the transistor TR2 is completely lowered and the capacitor C2 is set by the voltage Vin of the signal line SIG, the gradation is such that almost no current flows through the EL element 12. That is, when the EL element 12 is driven with the black gradation, the gradation of the pixel can be surely set to the black level, thereby providing a high-quality image.

(3) Effects of the embodiment According to the above configuration, the transistor is configured to have a source set to the reference voltage for setting the gate-source voltage with respect to the transistor that drives the light emitting element with the source follower circuit configuration. By not connecting to the power supply VCC, the power consumption when the gradation is set by setting the voltage to the capacitor provided between the gate and the source for the transistor that drives the light emitting element with the source follower circuit configuration. Can be reduced, and the influence from adjacent pixels can be effectively avoided.

  In the above-described embodiment, the case where the supply of the power supply VCC to the transistor TR2 is stopped by the transistor TR4 in the period including the period before and after setting the source to the reference voltage for setting the gate-source voltage has been described. However, the present invention is not limited to this, and the supply of the power supply VCC to the transistor TR2 may be stopped by the transistor TR4 only during the period in which the source is set to the reference voltage, and further, a partial period of this period Only the supply of the power supply VCC to the transistor TR2 may be stopped by the transistor TR4. In this way, the power consumption can be reduced correspondingly, and the influence of adjacent pixels can be avoided.

  In the above-described embodiment, the case where the supply of the power supply VCC to the transistor TR2 is stopped on the assumption that the wiring pattern for the reference voltage is provided in the vertical direction when the pixels are driven in units of lines has been described. The present invention is not limited to this, and can be widely applied to a case where a wiring pattern for a reference voltage is provided in the horizontal direction.

  In the above embodiment, the case where the EL element and the pixel circuit are integrally formed on the glass substrate by applying the amorphous silicon process has been described. However, the present invention is not limited to this, and the transistor is formed of polysilicon. In the case of creation, the present invention can be widely applied to a case where a drive circuit is created with a silicon substrate separately from the display portion and connected to and integrated with the display portion.

  In the above-described embodiments, the case where the organic EL light emitting element is driven by current is described. However, the present invention is not limited to this, and can be widely applied to display devices using various light emitting elements related to current driving.

  The present invention relates to a display device and a display device driving method, and can be applied to a self-luminous display device driven by current, such as an organic EL display device.

FIG. 3 is a connection diagram illustrating a pixel circuit of a display device according to an embodiment of the present invention together with peripheral components. It is a block diagram which shows the display apparatus by the pixel circuit of FIG. 2 is a time chart for explaining the operation of the pixel circuit of FIG. 1. FIG. 4 is a connection diagram for explaining the time chart of FIG. 3. It is a block diagram which shows the structure of a display apparatus. FIG. 6 is a connection diagram illustrating a pixel circuit of the display device of FIG. 5 together with a peripheral configuration. It is a characteristic curve figure which shows the characteristic of an organic EL element. It is a characteristic curve figure with which it uses for description of the change of the operating point of an organic EL element. FIG. 3 is a connection diagram illustrating a pixel circuit having a source follower circuit configuration along with a peripheral configuration. 10 is a time chart for explaining the operation of the pixel circuit of FIG. 9. FIG. 11 is a connection diagram for explaining the time chart of FIG. 10. It is a basic diagram with which it uses for description of the fluctuation | variation of a reference voltage. It is a basic diagram which shows vertical shading. It is a basic diagram which shows crosstalk.

Explanation of symbols

1, 11, 21, 31 ... Display device, 2, 23, 32 ... Display unit, 3, 22, 33 ... Pixel, 4, 24, 34 ... Vertical drive circuit, 4A, 24A, 34A ... Light Scan circuit 5, 25, 35 ... Horizontal drive circuit, 12 ... EL elements 24B, 34B, 34C ... Drive scan circuit, 25A, 35A ... Horizontal selector, C1, C2 ... Capacitors, TR1-TR4 ... Transistor

Claims (4)

In a display device having a display unit in which pixels driven by current are arranged in a matrix and a drive circuit for driving the display unit,
The pixel is
A light emitting element;
A transistor for driving the light emitting element by a source follower circuit configuration;
A capacitor provided between the gate and source of the transistor;
A switch circuit for power supply for stopping supply of power to the transistor;
A reference voltage switch circuit for connecting a source of the transistor to a reference voltage;
A signal line switch circuit for connecting the gate of the transistor to a signal line;
The drive circuit is
By driving the switch circuit for power supply, the switch circuit for reference voltage, and the switch circuit for signal line, the signal level of the signal line is set in the capacitor, and between the gate and source according to the signal level set in the capacitor The light-emitting element is current-driven with the transistor by voltage,
In setting the signal level to the signal line in the capacitor,
The source of the transistor is connected to the reference voltage by the reference voltage switch circuit, the gate of the transistor is connected to the signal line by the signal line switch circuit, and the potential of the signal line is applied to the capacitor. Set,
The display device characterized in that supply of power to the transistor is stopped by the power switch circuit during at least a period when the source of the transistor is connected to the reference voltage by the reference voltage switch circuit. 2. The display device according to claim 1, wherein the transistor, the switch circuit for power supply, the switch circuit for reference voltage, and the switch circuit for signal line are formed of n-channel MOS transistors. In a display device in which pixels driven by current are arranged in a matrix,
The pixel is
A light emitting element;
A transistor for driving the light emitting element by a source follower circuit configuration;
A capacitor provided between the gate and source of the transistor;
A reference voltage switch circuit for connecting a source of the transistor to a reference voltage, and setting a source potential of the transistor by the reference voltage;
For a signal line, the gate of the transistor is connected to a signal line and the signal level of the signal line is set in the capacitor during a period in which the source of the transistor is connected to the reference voltage by the reference voltage switch circuit. Switch circuit,
And a power supply switch circuit for stopping supply of power to the transistor during a period in which the source of the transistor is connected to the reference voltage by the reference voltage switch circuit. Display device. In a method for driving a display device having a display unit in which pixels driven by current are arranged in a matrix,
The pixel is
A light emitting element;
A transistor for driving the light emitting element by a source follower circuit configuration;
A capacitor provided between the gate and source of the transistor;
A switch circuit for power supply for stopping supply of power to the transistor;
A reference voltage switch circuit for connecting a source of the transistor to a reference voltage;
A signal line switch circuit for connecting the gate of the transistor to a signal line;
The driving method of the display device is:
By driving the switch circuit for power supply, the switch circuit for reference voltage, and the switch circuit for signal line, the signal level of the signal line is set in the capacitor, and between the gate and source according to the signal level set in the capacitor The light-emitting element is current-driven with the transistor by voltage,
In setting the signal level to the signal line in the capacitor,
The source of the transistor is connected to the reference voltage by the reference voltage switch circuit, the gate of the transistor is connected to the signal line by the signal line switch circuit, and the potential of the signal line is applied to the capacitor. Set,
Driving the display device, wherein supply of power to the transistor is stopped by the switch circuit for power supply at least during a period in which the source of the transistor is connected to the reference voltage by the switch circuit for reference voltage Method.

Images