JP2011118406A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device capable of driving display pixels (light emitting elements) arranged on a display panel at appropriate luminance gradation corresponding to display data, and giving high and uniform display quality. <P>SOLUTION: The display device 200 includes: a display panel 210; a selection driver 220; a power source driver 230; and a data driver 240. The data driver 240 includes: a detection voltage ADC 140 for measuring a threshold value voltage of a light-emission driving transistor disposed in each display pixel PX (light-emission driving circuit DC) during a threshold voltage detection period Tdec; a compensation voltage DAC 150 for applying a precharge voltage Vpre based on the measured threshold voltage to each display pixel PX; and a gradation signal generation part 130 for applying a gradation signal corresponding to display data to each display pixel. The power source driver 230 supplies supply voltages Vsc of high and low potentials for operating each pixel PX to emit light and not emit light to each display pixel PX. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display device, and in particular, a display in which a plurality of current-driven (or current-controlled) light-emitting elements that emit light at a predetermined luminance gradation by supplying a current according to display data are arranged. The present invention relates to a display device including a panel (display pixel array).

  In recent years, display devices that are light and thin and have low power consumption have been widely used as monitors and displays for personal computers and video equipment. In particular, a liquid crystal display device (LCD) is widely applied as a display device for portable devices (mobile devices) such as mobile phones, digital cameras, personal digital assistants (PDAs), and electronic dictionaries that have been popular in recent years.

  As a next-generation display device following such a liquid crystal display device, an organic electroluminescence element (organic EL element), an inorganic electroluminescence element (inorganic EL element), or a light emitting element such as a light emitting diode (LED) (self Research and development for full-scale popularization of light-emitting element type display devices (light-emitting element type displays) having a display panel in which light-emitting optical elements) are arranged in a matrix are actively performed.

  In particular, a light-emitting element type display using an active matrix driving method has a higher display response speed than the above-described liquid crystal display device, and has no viewing angle dependency, and has high luminance and high contrast, and display image quality. A feature that is extremely advantageous for application to portable devices that enables high definition, etc., and does not require a backlight like a liquid crystal display device, and can be further reduced in thickness and weight and power consumption. have.

  In such a light emitting element type display, various drive control mechanisms and control methods for controlling the operation (light emission state) of the light emitting element have been proposed. For example, Patent Document 1 discloses a drive circuit (light emission drive circuit) including a plurality of switching elements for controlling light emission of the light emitting elements in addition to the light emitting elements, for each display pixel constituting the display panel. A configuration with is described.

  FIG. 27 is a schematic configuration diagram showing a main part of a voltage-controlled active matrix light-emitting element type display according to the prior art, and FIG. FIG. Here, FIG. 28 shows a circuit configuration of a display pixel including an organic EL element as a light emitting element.

  As shown in FIG. 27, the active matrix organic EL display device described in Patent Document 1 generally includes a plurality of scanning lines (selection lines; Y-direction signal lines) SLp arranged in the row and column directions. A display panel 110P in which a plurality of display pixels EMp are arranged in a matrix in the vicinity of each intersection of data lines (signal lines; X direction signal lines) DLp, and a scanning driver (Y direction peripheral driving) connected to each scanning line SLp. Circuit) 120P and a data driver (X-direction peripheral drive circuit) 130P connected to each data line DL.

  As shown in FIG. 28, each display pixel EMp has a thin film transistor (TFT) Tr111 having a gate terminal connected to the scanning line SLp, a source terminal and a drain terminal connected to the data line DL and a contact N111, and a gate terminal. A light emission driving circuit DCp including a thin film transistor Tr112 connected to the contact N111 and having a source terminal applied with a predetermined power supply voltage Vdd; and an anode terminal connected to a drain terminal of the thin film transistor Tr112 of the light emission driving circuit DCp; An organic EL element (current control type light emitting element) OEL to which a ground potential Vgnd lower than the power supply voltage Vdd is applied to the cathode terminal is configured. In FIG. 28, Cp is a capacitor formed between the gate and source of the thin film transistor Tr112.

  In the display device including the display panel 110P including the display pixel EMp having such a configuration, first, the scan driver 120P sequentially applies the on-level scan signal voltage Ssel to the scan lines SLp of each row, The thin film transistor Tr111 of the display pixel EMp (light emission drive circuit DCp) for each row is turned on, and the display pixel EMp is set to the selected state.

  In synchronization with the selection timing, the gradation voltage Vpix corresponding to the display data is applied to the data line DLp of each column by the data driver 130P, thereby passing through the thin film transistor Tr111 of each display pixel EMp (light emission drive circuit DCp). A potential corresponding to the gradation voltage Vpix is applied to the contact N111 (that is, the gate terminal of the thin film transistor Tr112).

  As a result, the thin film transistor Tr112 is turned on in a conduction state (that is, a conduction state according to the gradation voltage Vpix) corresponding to the potential of the contact N111 (strictly, the potential difference between the gate and the source), and from the power supply voltage Vdd. A predetermined light emission drive current flows to the ground potential Vgnd via the thin film transistor Tr112 and the organic EL element OEL, and the organic EL element OEL emits light with a luminance gradation corresponding to display data (gradation voltage Vpix).

  Next, by applying an off-level scanning signal voltage Ssel to the scanning line SLp from the scanning driver 120P, the thin film transistor Tr111 of the display pixel EMp for each row is turned off, and the display pixel EMp is set to a non-selected state. The data line DLp and the light emission drive circuit DCp are electrically disconnected. At this time, the potential applied to the gate terminal (contact N111) of the thin film transistor Tr112 is held in the capacitor Cp, whereby a predetermined voltage is applied between the gate and the source of the thin film transistor Tr112, and the thin film transistor Tr112 is turned on. continue.

  Therefore, similarly to the light emission operation in the selected state, a predetermined light emission drive current flows from the power supply voltage Vdd to the organic EL element OEL via the thin film transistor Tr112, and the light emission operation is continued. This light emission operation is controlled so as to continue, for example, for one frame period until the gradation voltage Vpix corresponding to the next display data is applied (written) to the display pixel EMp of each row.

  In such a drive control method, the organic EL element OEL is adjusted by adjusting the voltage value of the gradation voltage Vpix applied to each display pixel EMp (specifically, the gate terminal of the thin film transistor Tr112 of the light emission drive circuit DCp). This is called a voltage gradation designation method (or voltage gradation designation drive) because the light emission driving current is controlled to emit light at a predetermined luminance gradation.

JP-A-8-330600 (Page 3, FIG. 4)

However, the display device provided with the light emission drive circuit corresponding to the voltage gradation designation method as described above in each display pixel has the following problems.
That is, in the light emission drive circuit DCp as shown in FIG. 28, a light emission drive thin film transistor in which a current path is connected in series to the organic EL element OEL and a light emission drive current according to display data (gradation voltage) flows. When the element characteristics (particularly the threshold voltage characteristics) of the Tr 112 change (shift) depending on the usage time, driving history, etc., the light emission that flows between the gate voltage (the potential of the contact 111) and the source-drain Since the relationship with the drive current (source-drain current) changes and the current value of the light emission drive current flowing at a predetermined gate voltage fluctuates (for example, decreases), appropriate luminance according to the display data There has been a problem that it is difficult to stably realize a light emitting operation at a gradation over a long period of time.

  Further, when the element characteristics (threshold voltage) of the thin film transistors Tr111 and Tr112 in the display panel 110P vary for each display pixel EMp (light emission drive circuit DCp), or for each display panel 110P depending on the manufacturing lot, When the element characteristics of Tr111 and Tr112 vary, the current value of the light emission drive current for each display pixel or each display panel in the voltage gradation designation type light emission drive circuit as described above. As a result, there is a problem that proper gradation control cannot be performed and a display device having a uniform display image quality cannot be provided.

  In view of the above-described problems, the present invention is arranged on a display panel with an appropriate luminance gradation according to display data by supplying a light emission drive current having an appropriate current value corresponding to the display data. An object is to provide a display device in which display pixels (light emitting elements) can be driven to emit light and display image quality is good and uniform.

  According to the first aspect of the present invention, a current control type light emitting element and light emission driving to the light emitting element are provided in the vicinity of intersections of the plurality of selection lines arranged in the row direction and the plurality of data lines arranged in the column direction. In a display device having a display panel provided with each of a plurality of display pixels provided with a light emitting drive element for supplying a current, a selection signal is applied to each selection line of the display panel, and each display in each row A selection driving unit that sets a pixel in a selection state during a selection period; and a gradation signal corresponding to a luminance gradation of display data for displaying desired image information is generated, and the row of the row set in the selection state is generated A data driving unit that supplies each display pixel, and a power supply that applies to the display pixels either a first voltage that causes the display pixels to perform a light emission operation or a second voltage that performs a non-light emission operation as a supply voltage A drive unit; and the selection drive unit; And a drive control unit that operates each of the data drive unit and the power supply drive unit at a predetermined timing, and the data drive unit supplies a voltage for threshold detection via the data lines. Detection voltage application means for applying to the light emission drive element of each display pixel in the row set to the selected state, and the threshold voltage detection voltage applied to the light emission drive element by the detection voltage application means Then, a voltage after a part of the electric charge corresponding to the threshold voltage detection voltage is discharged and converged is detected as the threshold voltage of the light emitting drive element via each data line. Based on the threshold voltage detection means and the detected threshold voltage, a compensation voltage for compensating the threshold voltage for each display pixel is created, and the compensation voltage is set to the selected state. For each display pixel in the row Compensation voltage application means for applying the gradation signal to the display pixel prior to supply to the display pixel, and the drive control unit is configured to perform all the operations arranged on the display panel by the selection drive unit and the data drive unit. The gradation signal corresponding to the display data is individually supplied to the display pixels, and the light-emitting elements provided in the display pixels emit light at a predetermined timing with luminance gradation corresponding to the display data. During the operation period to be operated, the second voltage as the supply voltage is supplied from the power supply driver to each display pixel in the row set to the selected state during the period including the selection period and longer than the selection period. To set a non-display period in which the display pixel is in a non-light-emitting display state, and during the non-display period, the threshold voltage detection means for the display pixels in at least one row of the display panel The threshold voltage is detected.

  According to a second aspect of the present invention, in the display device according to the first aspect, the threshold voltage is detected for each display pixel in a different row for each operation period.

  According to a third aspect of the present invention, in the display device according to the second aspect, the drive control unit causes the threshold voltage to be detected for each display pixel in a row adjacent to each other during the operation period. Features.

  According to a fourth aspect of the present invention, in the display device according to any one of the first to third aspects, the light emission driving element provided in each of the display pixels includes a current path for supplying the light emission driving current to the light emitting element. And a control terminal for controlling a supply state of the light emission drive current, and the detection voltage applying means is configured to detect the threshold value between the control terminal of the light emission drive element and one end side of the current path. The threshold voltage detection means calculates the potential difference between the control terminal of the light emission drive element and one end side of the current path when the current stops flowing in the current path. It is detected as a threshold voltage.

According to a fifth aspect of the present invention, in the display device according to any one of the first to fourth aspects, the data driver is associated with the threshold voltage detected by the threshold voltage detecting means. Storage means for storing threshold data for each display pixel, and the compensation voltage applying means is configured to apply the threshold value to the light emitting drive element based on the threshold data stored in the storage means. The compensation voltage for holding a voltage component corresponding to a voltage is generated and individually applied to the light emission drive element of the display pixel.
According to a sixth aspect of the present invention, in the display device according to the fifth aspect, the compensation voltage applying means is stored in the storage means between the control terminal of the light emission driving element and one end side of the current path. The compensation voltage based on the threshold data is held.
According to a seventh aspect of the present invention, in the display device according to any one of the first to sixth aspects, the threshold voltage detection means uses a digital signal as a threshold voltage of the light emission driving element detected as an analog signal. The threshold value data of the digital signal is stored, and the compensation voltage applying means is stored as a digital signal in the storage means. And a means for generating the compensation voltage comprising an analog signal for compensating the threshold voltage of the light emitting drive element based on the threshold data.

According to an eighth aspect of the present invention, in the display device according to any one of the first to seventh aspects, the data driver emits the light emitting element at a luminance gradation corresponding to the display data as the gradation signal. A gray scale current having a current value for operation is generated, and the gray scale current is individually supplied to each of the display pixels as the gray scale signal through each data line, and each data line is And a gradation signal generating means for supplying a write current corresponding to the gradation current to the current path of the light emitting drive element.
According to a ninth aspect of the present invention, in the display device according to the eighth aspect, the gradation signal generating means is configured to cause the light emitting element to perform a non-light emission operation when the luminance gradation of the display data is the lowest gradation. Means is provided for generating a non-light emitting display voltage having a predetermined voltage value.

  According to a tenth aspect of the present invention, in the display device according to the eighth or ninth aspect, the data driving unit outputs the threshold value data associated with the threshold voltage detected from each of the display pixels. Threshold acquisition means for individually capturing and sequentially transferring, and data acquisition means for sequentially capturing and holding the display data for generating the gradation signal for each of the display pixels, And the storage means stores the threshold data associated with the threshold voltage for each of the plurality of display pixels transferred from the threshold acquisition means for each of the plurality of display pixels. The gradation signal generation means generates the gradation signal corresponding to the display data for each of the plurality of display pixels held in the data acquisition means, and stores the plurality of tables. And supplying the gradation signal for each pixel.

According to an eleventh aspect of the present invention, in the display device according to the tenth aspect, the data acquisition unit and the threshold value acquisition unit individually acquire the display data sequentially, and the threshold value data individually. The sequential transfer configuration is shared.
According to a twelfth aspect of the present invention, in the display device according to any one of the first to eleventh aspects, the data driver detects at least the threshold voltage of the display pixel by the threshold voltage detection means. A signal path for applying the compensation voltage to the display pixel by the compensation voltage applying means, and a signal path for supplying the gradation signal to the display pixel by the gradation signal generating means, Signal path switching means for selectively switching control of connection with a single data line provided corresponding to a display pixel is provided.

  According to a thirteenth aspect of the present invention, in the display device according to the twelfth aspect, the data driver further includes a signal path for applying the threshold detection voltage to the display pixel by the detection voltage applying unit. The data line is configured to be selectively connected to a single data line.

  A fourteenth aspect of the present invention is the display device according to any one of the first to thirteenth aspects, wherein the power supply driving unit includes the plurality of display pixels arranged in the display panel in a plurality of groups in a plurality of rows. The drive control unit divides each display pixel of each group in a period in which any one of the display pixels included in each group is set to the selected state. A period in which each display pixel included in the group is set to a non-light emitting display state by applying the second voltage commonly to the display pixels, and the display pixels in the group are not set in the selection period In addition, the first voltage is commonly applied to the display pixels of the group, and the display pixels included in the group are set in a light emitting operation state.

  According to a fifteenth aspect of the present invention, in the display device according to any one of the first to fourteenth aspects, each of the display pixels includes a light emission drive circuit that controls a light emission operation of the light emitting element, and the light emission drive circuit includes: At least one end of the current path is applied with the supply voltage, and the other end of the current path is connected with a connection contact with the light emitting element, and a control terminal is connected to the selection line, The supply voltage is applied to one end of the current path, the second switch means in which the control terminal of the first switch means is connected to the other end of the current path, the control terminal is connected to the selection line, and the current A third switch means having the data line connected to one end of the path and the connection contact connected to the other end of the current path, and the light emission drive element is the first switch means, The detection voltage applying means includes the A voltage for detecting the threshold value is applied between the control terminal of the first switch means and the connection contact, and the threshold voltage detection means includes the control terminal of the first switch means and the control terminal; The potential between the connection contacts is detected as the threshold voltage, and the compensation voltage application means is stored in the storage means between the control terminal of the first switch means and the connection contact. Further, the compensation voltage based on the threshold data is applied.

According to a sixteenth aspect of the present invention, in the display device according to the fifteenth aspect, the first to third switch means are field effect transistors each including a semiconductor layer made of amorphous silicon.
According to a seventeenth aspect of the present invention, in the display device according to any one of the first to sixteenth aspects, the light emitting element is an organic electroluminescent element.

  According to the display device of the present invention, the data driver (display drive device) is unique to the light emission drive switching element (thin film transistor) provided in the light emission drive circuit of the display pixels in each row arranged in the display panel. A threshold voltage (threshold value) of the switching element detected for each display pixel immediately before the writing operation of display data (gradation signal) to the display pixel of each row is provided. Based on the data), the switching element for each display pixel can be set to a state in which each threshold voltage is compensated by holding a voltage component corresponding to a threshold voltage unique to each display pixel. Even when the threshold voltage of the switching element (thin film transistor) changes due to a change with time, driving history, or the like (Vth shift), the influence is suppressed and the switching voltage is reduced. It is possible to hold the appropriate voltage component corresponding to the gradation signal quenching element, it can emit light action display pixels (light emitting elements) at an appropriate luminance gradation.

  In particular, in the display device according to the present invention, the threshold voltage detection operation is executed for display pixels in a specific row during an operation period in which the light emitting elements are operated to emit light at a luminance gradation corresponding to display data. As a result, it is possible to constantly monitor the threshold voltage (Vth shift state) at the time of execution of the threshold voltage detection operation for the display pixels in any row arranged on the display panel. In the precharge operation executed prior to the operation, a voltage component (charge) corresponding to the threshold voltage specific to the light emission driving switching element of each display pixel is retained (threshold voltage is individually compensated) In the write operation, only the voltage component corresponding to the display data needs to be added and charged, and the voltage component based on the display data can be quickly and appropriately applied. It can be written to.

  Further, each display pixel is provided with a power supply driving unit that applies either a first voltage for causing each display pixel to perform a light emission operation or a second voltage for performing a non-light emission operation as a supply voltage. A configuration in which a second voltage is applied as a supply voltage to each display pixel in a row including a selection period and longer than the selection period to set the display pixel in a non-light-emitting display state. When displaying a moving image, since a black display period is inserted during the display period, the display quality of the moving image can be improved as compared with the case where the moving image is displayed continuously.

1 is a main part configuration diagram illustrating an example of a display driving device applicable to a display device according to the present invention and a display pixel that is driven and controlled by the display driving device. 6 is a timing chart showing a threshold voltage detection operation in a display driving device applicable to the display device according to the present invention. It is a conceptual diagram which shows the voltage application operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. It is a conceptual diagram which shows the voltage convergence operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. It is a conceptual diagram which shows the voltage reading operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. FIG. 6 is a diagram illustrating an example of a drain-source current characteristic when an n-channel thin film transistor has a gate-source voltage set to a predetermined condition and a drain-source voltage is modulated. 4 is a timing chart showing a drive control method (gradation display operation) in a display drive device applicable to the display device according to the present invention. It is a conceptual diagram which shows the precharge operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. It is a conceptual diagram which shows the data write-in operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. It is a conceptual diagram which shows the light emission operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. It is a principal part block diagram which shows the other structural example of the display drive device applicable to the display apparatus which concerns on this invention. It is a timing chart which shows the drive control method (non-light emission display operation | movement) in the display drive device applicable to the display apparatus which concerns on this invention. It is a conceptual diagram which shows the other example of the data write-in operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. It is a conceptual diagram which shows the non-light-emission operation | movement in the display drive device applicable to the display apparatus which concerns on this invention. It is a schematic block diagram which shows an example of the whole structure of the display apparatus which concerns on this invention. It is a schematic block diagram which shows an example of the display panel applied to the display apparatus which concerns on this invention, and its peripheral circuit (selection driver, power supply driver). 3 is a timing chart schematically showing a first example of a display device drive control method according to the present invention. 6 is a timing chart schematically showing a second example of the display device drive control method according to the present invention. It is a principal part block diagram which shows an example of the display apparatus for implement | achieving the 2nd example of the drive control method of the display apparatus which concerns on this invention. 6 is a timing chart schematically showing a third example of the display device drive control method according to the present invention. 6 is a timing chart schematically showing a modification (No. 1) of the second example of the drive control method for a display device according to the present invention. 6 is a timing chart schematically showing a modification (No. 1) of the third example of the drive control method for the display device according to the present invention. 6 is a timing chart schematically showing a modification (No. 2) of the second example of the drive control method for the display device according to the present invention. 6 is a timing chart schematically showing a modification (No. 2) of the third example of the drive control method for the display device according to the present invention. 6 is a timing chart schematically showing a fourth example of the display device drive control method according to the present invention. It is a principal part block diagram which shows an example of the display apparatus for implement | achieving the 4th example of the drive control method of the display apparatus which concerns on this invention. It is a schematic block diagram which shows the principal part of the voltage control active matrix light emitting element type display in a prior art. It is an equivalent circuit diagram which shows the structural example of the display pixel (light emission drive circuit and light emitting element) applicable to the light emitting element type display in a prior art.

Hereinafter, a display device and a drive control method thereof according to the present invention will be described in detail with reference to embodiments.
First, a display drive device applicable to the display device according to the present invention and a drive control method thereof will be described with reference to the drawings.

  FIG. 1 is a main part configuration diagram showing an example of a display driving device applicable to the display device according to the present invention and a display pixel that is driven and controlled by the display driving device. Here, the relationship between a specific display pixel arranged on the display panel of the display device and a display drive device that controls the light emission drive of the display pixel will be described.

<Display drive device>
As shown in FIG. 1, a display driving device 100 applicable to the display device according to the present invention generally includes a shift register / data register unit 110, a display data latch unit 120, and a gradation signal generation unit 130. Threshold detection voltage analog-to-digital converter (hereinafter abbreviated as “detection voltage ADC” and in the figure, expressed as “VthADC”) 140, and threshold compensation voltage digital-to-analog converter (hereinafter referred to as “compensation”). "Voltage DAC" is abbreviated as "VthDAC" in the figure) 150, threshold data latch part (in the figure as "Vth data latch part") 160, frame memory 170, And a data line input / output switching unit 180.

  The shift register / data register unit (data acquisition means, threshold value acquisition means) 110 is a shift register that sequentially outputs shift signals, not shown, and a digital signal supplied at least from the outside based on the shift signals And a data register for sequentially taking in luminance gradation data. More specifically, an operation of sequentially fetching display data (luminance gradation data) of display pixels for one row of the display panel, which is sequentially supplied from the outside, and transferring it to the display data latch unit 120 described later, or detection A threshold voltage (threshold detection data) of one row of display pixels converted into a digital signal by the voltage ADC 140 and held in the threshold data latch unit 160 is sequentially fetched and transferred to a frame memory 170 described later. Either the operation or the operation of sequentially fetching threshold compensation data of display pixels for a specific row from the frame memory 170 and transferring the data to the threshold data latch unit 160 is selectively executed. Each of these operations will be described in detail later.

The display data latch unit 120 holds the display data (luminance gradation data) of the display pixels for one row transferred from the outside by the shift register / data register unit 110 and transferred.
A gradation signal generation unit (gradation signal generation means) 130 causes an organic EL element (current-controlled light-emitting element) OEL provided in a display pixel PX, which will be described later, to emit light with a luminance gradation corresponding to display data. As a gradation signal, a gradation current Idata having a predetermined current value or a level for causing the organic EL element OEL to perform a non-light emission operation (set to a black display (minimum luminance gradation) state without performing a light emission operation). A function of selectively supplying any one of the non-light emitting display voltages Vzero having a predetermined voltage value as the adjustment signal is provided.

  Here, as a configuration for supplying a gray scale current having a current value corresponding to display data as a gray scale signal, for example, the display data is based on a gray scale reference voltage supplied from power supply means (not shown). A digital-analog converter (D / A converter) that converts a digital signal voltage of each display data held in the latch unit 120 into an analog signal voltage, and a gradation current Idata having a current value corresponding to the analog signal voltage A configuration including a voltage-current converter that generates

  In the following description, a case where a gradation current having a predetermined current value is supplied to each display pixel as a gradation signal and light emission operation (gradation display) is performed at a predetermined luminance gradation will be described. The present invention is not limited to this, and as a gradation signal, a gradation voltage having a voltage value corresponding to the display data may be applied to perform a light emission operation at a predetermined luminance gradation. In this case, for example, a configuration including only the digital-analog converter can be applied.

  The detection voltage ADC (threshold voltage detection means) 140 is a threshold of a switching element (thin film transistor Tr13) that supplies a light emission driving current to a light emitting element (for example, an organic EL element OEL) provided in each display pixel PX described later. A value voltage (or a voltage component corresponding to the threshold voltage) is taken (measured) as an analog signal voltage and converted into threshold detection data composed of a digital signal voltage.

  A compensation voltage DAC (compensation voltage application means, detection voltage application means) 150 receives threshold compensation data including digital signal voltages for compensating the threshold voltage of the switching element provided in each display pixel PX. Then, it is converted into a precharge voltage (compensation voltage) composed of an analog signal voltage. Further, as shown in a drive control method described later, in the operation of measuring the threshold voltage of the switching element by the detection voltage ADC 140 (threshold voltage detection operation), between the gate and the source of the thin film transistor constituting the switching element ( A predetermined detection voltage can be output so that a potential difference higher than the threshold voltage of the switching element is set (a voltage component is held) at both ends of the capacitor Cs.

  The threshold data latch unit 160 captures and holds threshold detection data converted and generated by the detection voltage ADC 140 for each display pixel PX for one row, and stores the threshold detection data. An operation of sequentially transferring to a frame memory 170 (to be described later) via the shift register / data register unit 110, or a threshold value for each display pixel PX for one row corresponding to the threshold detection data from the frame memory 170 One of the operations of sequentially acquiring and holding the compensation data and transferring the threshold compensation data to the compensation voltage DAC 150 is selectively executed.

  Further, the frame memory (storage means) 170 includes the detection voltage ADC 140 and the threshold data latch unit prior to the writing operation of the display data (luminance gradation data) to each display pixel PX arranged on the display panel. The threshold detection data based on the threshold voltage detected for each display pixel PX for one row by 160 is sequentially taken in via the shift register / data register unit 110 to display one display panel (one frame). Are stored individually for each display pixel PX, and the threshold detection data is used as threshold compensation data or the threshold compensation data corresponding to the threshold detection data is used as a shift register / data register. The data are sequentially output via the unit 110 and transferred to the threshold data latch unit 160 (compensation voltage DAC 150).

  The data line input / output switching unit (signal path switching means) 180 is a threshold of the switching element (thin film transistor) provided in each display pixel PX via the data line DL arranged in the column direction of the display panel. A voltage detection side switch 181 for taking the value voltage into the detection voltage ADC 140 and measuring it, and at least a precharge voltage for compensating the threshold voltage of the switching element provided in each display pixel PX, or For selecting a mode for supplying one of the gradation signals (gradation current or non-emission display voltage) for causing each display pixel PX to emit light at a luminance gradation corresponding to the display data. The input selection switch 182 and the precharge voltage or gradation signal selected by the input signal selection switch 182 are used as a data write. The writing side switch 183 to be supplied to the display pixels PX via the DL, and has a configuration with a.

  Here, the voltage detection side switch 181 and the write side switch 183 can be configured by, for example, thin film transistors (field effect transistors) having different channel polarities, and as shown in FIG. A channel thin film transistor can be used, and an n-channel thin film transistor can be used as the writing-side switch 183. The gate terminals (control terminals) of these thin film transistors are connected to the same signal line, and the ON and OFF states are controlled based on the signal level of the switching control signal AZ applied to the signal line.

<Display pixel>
Further, as shown in FIG. 1, the display pixel PX applicable to the display device according to the present invention includes a selection line SL and a column direction (vertical direction in the drawing) arranged in the row direction (horizontal direction in the drawing) of the display panel. The organic EL element OEL, which is a current-controlled light emitting element, and a light emission drive having a current value corresponding to display data in the organic EL element OEL And a light emission driving circuit DC for supplying a current.

  In the light emission drive circuit DC, for example, a gate terminal (control terminal) is applied to the selection line SL, and a drain terminal and a source terminal (one end and the other end of the current path) are supplied with a supply voltage line VL and a contact. The thin film transistor (second switch means) Tr11 connected to N11, the gate terminal (control terminal) to the selection line SL, the source terminal and the drain terminal (one end and the other end of the current path) to the data line DL and the contact N12 The thin film transistor (third switch means) Tr12 and the gate terminal (control terminal) are connected to the contact N11, the drain terminal and the source terminal (one end and the other end of the current path) are connected to the supply voltage line VL and the contact (connection), respectively. Thin film transistor (light emitting drive element, first switch means) Tr13 connected to each of the contacts N12, the contact N11 and the contacts Between 12 (the thin film transistor Tr13 gate - between the source terminal) has a capacitor Cs connected, the configuration with. Here, the thin film transistor Tr13 corresponds to a light emission driving switching element whose threshold voltage is measured by the detection voltage ADC 140 and the threshold data latch unit 160 in the display driving device 100 described above.

  The organic EL element OEL has an anode terminal connected to the contact N12 of the light emission drive circuit DC, and a common voltage Vcom applied to the cathode terminal. Here, the common voltage Vcom is used in a write operation period in which a grayscale signal (grayscale current or non-light emitting display voltage) corresponding to display data is supplied to the light emission drive circuit DC in a display drive operation described later. The light emission driving current is supplied to the organic EL element (light emitting element) OEL which is equal to or higher than the supply voltage Vsc set to the low potential (Vs). In the light emission operation period in which the light emission operation is performed at a predetermined luminance gradation, the potential is set to an arbitrary potential (for example, ground potential GND) that is lower than the supply voltage Vsc set to the high potential (Ve). (Vs ≦ Vcom <Ve).

  Here, the capacitor Cs may be a parasitic capacitance formed between the gate and the source of the thin film transistor Tr13. In addition to the parasitic capacitance, a capacitor is further connected in parallel between the contact N11 and the contact N12. There may be. Further, the thin film transistors Tr11 to Tr13 are not particularly limited. However, by forming all the thin film transistors Tr11 to Tr13 by n channel thin film transistors, n channel amorphous silicon thin film transistors can be favorably applied. In this case, by applying an already established amorphous silicon manufacturing technique, a light emission driving circuit composed of an amorphous silicon thin film transistor having stable element characteristics (such as electron mobility) can be manufactured by a relatively simple manufacturing process. In the following description, a case where all the thin film transistors Tr11 to Tr13 are configured by n-channel thin film transistors will be described. Further, the light emitting element driven to emit light by the light emission driving circuit DC is not limited to the organic EL element OEL, and may be another light emitting element such as a light emitting diode as long as it is a current control type light emitting element. .

<Display Drive Device / Display Pixel Drive Control Method>
Next, a drive control method (drive control operation) in a case where gradation display is performed by causing the light emitting elements of the display pixels to perform a light emission operation in the display driving device having the above-described configuration will be described with reference to the drawings.

  The drive control operation in the display drive device 100 described above is roughly divided into the light emission drive thin film transistor Tr13 (switching element; light emission drive element) provided in each display pixel PX (light emission drive circuit DC) arranged in the display panel. A threshold voltage detection operation (threshold voltage detection period) for measuring and storing the threshold voltage, and a thin film transistor for light emission driving provided in each display pixel PX after completion of the threshold voltage detection operation A voltage component corresponding to the threshold voltage is held in Tr13 (threshold voltage is compensated), and a gradation signal (a gradation current having a predetermined current value) corresponding to display data is written, and the gradation And a display driving operation (display driving period) for causing the organic EL element OEL to emit light at a desired luminance gradation corresponding to the signal. Here, the threshold voltage detection operation is executed at an arbitrary timing prior to the display driving operation.

Hereinafter, each control operation will be described.
(Threshold voltage detection operation)
FIG. 2 is a timing chart showing a threshold voltage detection operation in a display driving device applicable to the display device according to the present invention. 3 is a conceptual diagram showing a voltage application operation in a display driving device applicable to the display device according to the present invention, and FIG. 4 is a voltage convergence in the display driving device applicable to the display device according to the present invention. FIG. 5 is a conceptual diagram showing a voltage reading operation in a display driving device applicable to the display device according to the present invention. FIG. 6 is a diagram illustrating an example of drain-source current characteristics when the gate-source voltage is set to a predetermined condition and the drain-source voltage is modulated in an n-channel thin film transistor. .

  As shown in FIG. 2, the threshold voltage detection operation in the display driving device 100 is performed on the display pixel PX from the display driving device 100 via the data line DL within a predetermined threshold voltage detection period Tdec. A voltage component corresponding to the detection voltage Vpv is applied between the gate and the source of the light emission driving thin film transistor Tr13 provided in the light emission drive circuit DC of the display pixel PX by applying a voltage detection voltage (detection voltage Vpv). Is held (that is, a charge corresponding to the detection voltage Vpv is accumulated in the capacitor Cs), and is held between the gate and the source of the thin film transistor Tr13 during the voltage application period (detection voltage application step) Tpv. A part of the voltage component (charge accumulated in the capacitor Cs) is discharged, and the threshold value of the drain-source current Ids of the thin film transistor Tr13. Only the voltage component (charge) corresponding to the value voltage is held between the gate and source of the thin film transistor Tr13 (remaining in the capacitor Cs), and after the voltage convergence period Tcv has elapsed, the gate and source of the thin film transistor Tr13 The voltage component held between them (voltage value based on the charge remaining in the capacitor Cs; threshold voltage Vth13) is measured, converted into digital data, and stored (stored) in a predetermined storage area of the frame memory 170. And a voltage reading period (threshold voltage detection step) Trv (Tdec ≧ Tpv + Tcv + Trv).

  Here, the threshold voltage Vth13 of the drain-source current Ids of the thin film transistor Tr13 is an operating boundary where the drain-source current Ids of the thin film transistor Tr13 starts to flow when a slight voltage is further applied between the drain and source. The gate-source voltage Vgs of the thin film transistor Tr13. In particular, the threshold voltage Vth13 measured in the voltage reading period Trv according to the present invention is a drive history (light emission history), usage time (time-dependent change), and the like with respect to the threshold voltage in the initial manufacturing state of the thin film transistor Tr13. Shows the threshold voltage at the time of execution of the threshold voltage detection operation after fluctuation (Vth shift) occurs.

Hereinafter, each operation period related to the threshold voltage detection operation will be described in more detail.
(Voltage application period)
First, in the voltage application period Tpv, as shown in FIGS. 2 and 3, an on-level (high level) selection signal Ssel is applied to the selection line SL of the light emission drive circuit DC, and the supply voltage line VL is applied to the supply voltage line VL. A low-potential supply voltage Vsc (= Vs) is applied. Here, the low potential supply voltage Vsc (= Vs) may be a voltage equal to or lower than the common voltage Vcom, and may be, for example, the ground potential GND.

  On the other hand, in synchronization with this timing, the switching control signal AZ is set to a high level, the writing side switch 183 is set to the on state, the voltage detection side switch 181 is set to the off state, and the input selection switch 182 is set to the compensation voltage. By switching to the DAC 150 side, the threshold voltage detection voltage Vpv output from the compensation voltage DAC 150 is passed through the data line input / output switching unit 180 (input selection switch 182 and write side switch 183). , Applied to the data line DL.

  Thereby, the thin film transistors Tr11 and Tr12 provided in the light emission drive circuit DC constituting the display pixel PX are turned on, and the supply voltage Vsc is supplied to the gate terminal of the thin film transistor Tr13 and one end side of the capacitor Cs (contact N11) via the thin film transistor Tr11. The detection voltage Vpv applied to the data line DL is applied to the source terminal of the thin film transistor Tr13 and the other end side (contact N12) of the capacitor Cs via the thin film transistor Tr12.

  Here, in the display pixel PX (light emission drive circuit DC), with respect to the n-channel type thin film transistor Tr13 that supplies the light emission drive current to the organic EL element OEL, the drain-source voltage at the predetermined gate-source voltage Vgs. When the change characteristic of the drain-source current Ids when Vds is modulated is verified, it can be represented by a characteristic diagram as shown in FIG.

  In FIG. 6, the horizontal axis represents the partial pressure of the thin film transistor Tr13 and the partial pressure of the organic EL element OEL connected in series thereto, and the vertical axis represents the current value of the drain-source current Ids of the thin film transistor Tr13. A one-dot chain line in the figure is a boundary line of the threshold voltage between the gate and the source of the thin film transistor Tr13, the left side of the boundary line is an unsaturated region, and the right side is a saturated region. The solid line shows the gate-source voltage Vgs of the thin film transistor Tr13, the voltage Vgsmax at the time of light emission operation at the maximum luminance gradation, and the voltage Vgs1 at the time of light emission operation at any (different) luminance gradation below the maximum luminance gradation. The graph shows the change characteristics of the drain-source current Ids when the drain-source voltage Vds of the thin film transistor Tr13 is modulated when fixed to (<Vgsmax) and Vgs2 (<Vgs1). A broken line is a load characteristic line (EL load line) when the organic EL element OEL is caused to emit light, and a voltage on the right side of the EL load line is a voltage between the supply voltage Vsc and the common voltage Vcom (as an example, in the drawing). 20V), and the left side of the EL load line corresponds to the drain-source voltage Vds of the thin film transistor Tr13. The partial pressure of the organic EL element OEL gradually increases as the luminance gradation increases, that is, as the current value of the drain-source current Ids (light emission drive current≈gradation current) of the thin film transistor Tr13 increases.

  In FIG. 6, in the unsaturated region, even if the gate-source voltage Vgs of the thin film transistor Tr13 is set constant, the drain-source current Ids is increased as the drain-source voltage Vds of the thin film transistor Tr13 increases. The value is significantly increased (changes). On the other hand, in the saturation region, when the gate-source voltage Vgs of the thin film transistor Tr13 is set constant, even if the drain-source voltage Vds increases, the drain-source current Ids of the thin film transistor Tr13 does not increase so much and is substantially constant. It becomes.

  Here, in the voltage application period Tpv, the detection voltage Vpv applied from the compensation voltage DAC 150 to the data line DL (further, the source terminal of the thin film transistor Tr13 of the display pixel PX (light emission drive circuit DC)) has a low potential. In the characteristic diagram shown in FIG. 6 which is sufficiently lower than the set supply voltage Vsc (= Vs), the drain-source voltage Vds in the region where the gate-source voltage Vgs of the thin film transistor Tr13 exhibits saturation characteristics is obtained. Is set to such a voltage value. For example, the detection voltage Vpv may be set to the maximum voltage that can be applied from the compensation voltage DAC 150 to the data line DL.

Further, the detection voltage Vpv is set so as to satisfy the following expression (1).
| Vs-Vpv |> Vth12 + Vth13 (1)
In the above equation (1), Vth12 is a threshold voltage between the drain and source of the thin film transistor Tr12 when the on-level selection signal Ssel is applied to the gate terminal of the thin film transistor Tr12. In addition, since the low-potential supply voltage Vsc (= Vs) is applied to both the gate terminal and the drain terminal of the thin film transistor 13 and they are substantially equal to each other, Vth13 is a voltage between the drain and source of the thin film transistor Tr13. It is a threshold voltage, and is also a threshold voltage between the gate and source of the thin film transistor Tr13. Although Vth12 + Vth13 gradually increases with time, the potential difference of (Vs−Vpv) is set large so as to always satisfy the equation (1).

  Thus, by applying a potential difference Vcp (both end potential Vc) larger than the threshold voltage Vth13 of the thin film transistor Tr13 between the gate and the source of the thin film transistor Tr13 (that is, both ends of the capacitor Cs), the voltage Vcp is applied. A corresponding large current Ipv for detection flows forcibly from the supply voltage line VL toward the compensation voltage DAC 150 via the drain-source of the thin film transistor Tr13. Therefore, electric charges corresponding to the potential difference based on the detection current Ipv are quickly accumulated at both ends of the capacitor Cs (that is, the voltage Vcp is charged in the capacitor Cs). In the voltage application period Tpv, not only charges are accumulated in the capacitor Cs, but also the detection current Ipv flows through other capacitance components in the current route from the supply voltage line VL to the data line DL, so Accumulation is performed.

  At this time, since the common voltage Vcom (= GND) higher than the low-potential supply voltage Vsc (= Vs) applied to the supply voltage line VL is applied to the cathode terminal of the organic EL element OEL, the organic EL element The anode-cathode is set between the anode and the cathode of the element OEL, and the light emission drive current does not flow through the organic EL element OEL, and the light emission operation is not performed.

(Voltage convergence period)
Next, in the voltage convergence period Tcv after the end of the voltage application period Tpv, as shown in FIGS. 2 and 4, an on-level selection signal Ssel is applied to the selection line SL, and a low potential is applied to the supply voltage line VL. When the supply voltage Vsc (= Vs) is applied, the switching control signal AZ is switched to the low level, so that the voltage detection side switch 181 is set to the on state and the write side switch 183 is Set to off state. Further, the output of the detection voltage Vpv from the compensation voltage DAC 150 is stopped. Accordingly, since the thin film transistors Tr11 and Tr12 are kept on, the display pixel PX (light emission drive circuit DC) is electrically connected to the data line DL, but the voltage application to the data line DL is performed. Therefore, the other end side (contact N12) of the capacitor Cs is set to a high impedance state.

  At this time, the gate voltage of the thin film transistor Tr13 is held by the electric charge (both-end potential Vc = Vcp> Vth13) accumulated in the capacitor Cs in the voltage application period Tpv described above, and the thin film transistor Tr13 is held in the ON state. Since the current continues to flow between the drain and source, the potential on the source terminal side (contact N12; the other end side of the capacitor Cs) of the thin film transistor Tr13 gradually increases so as to approach the potential on the drain terminal side (supply voltage line VL side). I will do it.

  As a result, a part of the electric charge accumulated in the capacitor Cs is discharged, the gate-source voltage Vgs of the thin film transistor Tr13 is lowered, and finally converges on the threshold voltage Vth13 of the thin film transistor Tr13. Change. Along with this, the drain-source current Ids of the thin film transistor Tr13 decreases, and the current flow finally stops.

  Even during this voltage convergence period Tcv, the potential of the anode terminal (contact N12) of the organic EL element OEL is equal to or less than the common voltage Vcom on the cathode terminal side. No voltage or reverse bias voltage is still applied to the organic EL element OEL, and the organic EL element OEL does not perform light emission.

(Voltage reading period)
Next, in the voltage reading period Trv after the lapse of the voltage convergence period Tcv, as shown in FIGS. 2 and 5, an on-level selection signal Ssel is applied to the selection line SL as in the voltage convergence period Tcv. , The detection voltage ADC 140 electrically connected to the data line DL and the threshold in the state where the low-potential supply voltage Vsc (= Vs) is applied to the supply voltage line VL and the switching control signal AZ is set to the low level. The value data latch unit 160 measures the potential (detection voltage Vdec) of the data line DL.

  Here, the data line DL after the lapse of the voltage convergence period Tcv is in a state of being connected to the source terminal (contact N12) side of the thin film transistor Tr13 through the thin film transistor Tr12 set in the ON state. Thus, the potential on the source terminal (contact N12) side of the thin film transistor Tr13 corresponds to the potential on the other end side of the capacitor Cs in which charges corresponding to the threshold voltage Vth13 of the thin film transistor Tr13 are accumulated.

  On the other hand, the potential on the gate terminal (contact N11) side of the thin film transistor Tr13 is a potential on one end side of the capacitor Cs in which electric charges corresponding to the threshold voltage Vth13 of the thin film transistor Tr13 are accumulated, and at this time, it is set to the on state. The thin film transistor Tr11 is connected to a low potential supply voltage Vsc.

  As a result, the potential of the data line DL measured by the detection voltage ADC 140 corresponds to the potential on the source terminal side of the thin film transistor Tr13 or the potential corresponding to the potential, so the detection voltage Vdec and the preset voltage Is determined based on the difference (potential difference) from the low-potential supply voltage Vsc (for example, the ground potential GND), that is, the gate-source voltage Vgs of the thin film transistor Tr13 (the potential Vc across the capacitor Cs), that is, the thin film transistor Tr13. Threshold voltage Vth13 or a voltage corresponding to the threshold voltage Vth13 can be detected.

  Then, the threshold voltage Vth13 (analog signal voltage) of the thin film transistor Tr13 detected in this way is converted into threshold detection data composed of a digital signal voltage by the detection voltage ADC 140, and the threshold data latch unit 160 is converted. The threshold detection data of each display pixel PX for one row is sequentially read out by the shift register / data register unit 110 and stored (stored) in a predetermined storage area of the frame memory 170. Here, the threshold voltage Vth13 of the thin film transistor Tr13 provided in the light emission drive circuit DC of each display pixel PX has a different degree of variation (Vth shift) depending on the drive history (light emission history) in each display pixel PX. The frame memory 170 stores threshold value detection data unique to each display pixel PX.

Such a series of threshold voltage detection operations are executed at an arbitrary timing prior to the display driving operation described later. Specifically, as described in the driving control method of the display device described later, the display panel is operated. The threshold voltage detection operation is executed for the display pixels in a specific row within one frame period in which the display drive operation is executed for all the arranged display pixels, and the specific target that is the target of the threshold voltage detection operation. Precharge for detecting the threshold voltage of the display pixel in any row at any time by shifting the row for each frame period and compensating the threshold voltage of each display pixel in the display driving operation described later Controlled to use for operation.
In each of the embodiments of the display device drive control method to be described later, for the sake of simplicity, only one specific row is used. However, the present invention is not limited to this, and all the rows of the display panel are used. It may be a plurality of lines consisting of a part of two or more lines.

(Display drive operation: gradation display operation)
FIG. 7 is a timing chart showing a drive control method (gradation display operation) in a display drive device applicable to the display device according to the present invention. 8 is a conceptual diagram showing a precharge operation in a display driving device applicable to the display device according to the present invention, and FIG. 9 is a data document in the display driving device applicable to the display device according to the present invention. FIG. 10 is a conceptual diagram showing a light emitting operation in a display driving device applicable to the display device according to the present invention.

  As shown in FIG. 7, the display driving operation (gradation display operation) in the display driving device 100 described above is performed from the display driving device 100 via the data line DL within a predetermined display driving period (one processing cycle period) Tcyc. Then, a predetermined precharge voltage Vpre is applied to the display pixel PX, and between the gate and source of the light emission driving thin film transistor Tr13 provided in the light emission driving circuit DC of the display pixel PX, between the drain and source of the thin film transistor Tr13. A precharge period (compensation voltage application step) Tth in which a voltage component corresponding to the threshold voltage Vth13 of the current Ids is held (charge is accumulated or discharged in the capacitor Cs) to compensate the threshold voltage, and display data Is applied to the display pixel PX (light emission drive circuit DC) via the data line DL, and a thin film transistor is applied. Write operation for writing a gradation signal by adding a voltage component corresponding to the threshold voltage Vth13 held in the precharge period Tth to the voltage component corresponding to the gradation signal between the gate and source of the star Tr13 Light emission having a current value corresponding to display data based on a period (data writing step) Twrt and all voltage components (total charge accumulated in the capacitor Cs) held between the gate and source of the thin film transistor Tr13. It is set to include a light emission operation period (gradation light emission step) Tem in which a drive current is passed through the organic EL element OEL to perform light emission operation at a predetermined luminance gradation (Tcyc ≧ Tth + Twrt + Tem).

  Here, one processing cycle period applied to the display drive period Tcyc is set to a period required for the display pixel PX to display image information for one pixel of one frame image, for example. That is, as described in the drive control method for the display device to be described later, when one frame image is displayed on a display panel in which a plurality of display pixels PX are arranged in a matrix in the row direction and the column direction, the one processing cycle period. Tcyc is set to a period required for the display pixels PX for one row to display one row of images in one frame image.

Hereinafter, each operation period related to the display driving operation will be described in more detail.
(Precharge period)
First, in the precharge period Tth, as in the voltage application period Tpv described above, an on-level (high-level) selection signal Ssel is applied to the selection line SL of the light emission drive circuit DC, as shown in FIGS. In addition, a low-potential supply voltage Vsc (= Vs; for example, ground potential GND) is applied to the supply voltage line VL.

  Thereby, the thin film transistors Tr11 and Tr12 provided in the light emission drive circuit DC are turned on, and the supply voltage Vsc is applied to the gate terminal (contact N11; one end side of the capacitor Cs) of the thin film transistor Tr13 through the thin film transistor Tr11. The source terminal (contact N12) of the thin film transistor Tr13 is electrically connected to the data line DL via the thin film transistor Tr12.

On the other hand, in synchronization with this timing, the switching control signal AZ is set to a high level, the writing side switch 183 is set to the on state, the voltage detection side switch 181 is set to the off state, and the input selection switch 182 is set to the compensation voltage. The setting is switched to the DAC 150 side.
As a result, the precharge voltage Vpre output from the compensation voltage DAC 150 is applied to the data line DL via the data line input / output switching unit 180 (the input selection switch 182 and the write side switch 183), and further the light emission. The precharge voltage Vpre is applied to the source terminal (contact N12) of the thin film transistor Tr13 through the thin film transistor Tr12 provided in the drive circuit DC.

  Here, in the precharge period Tth, the precharge voltage Vpre applied to the source terminal (contact N12) of the thin film transistor Tr13 of the display pixel PX (light emission drive circuit DC) from the compensation voltage DAC 150 via the data line DL is: In the threshold voltage detection operation described above, the threshold voltage detection that is detected for each display pixel PX by the detection voltage ADC 140 and the threshold data latch unit 160 and is individually stored in the frame memory 170 for each display pixel PX. Based on the data, the thin film transistor Tr13 has a voltage value that compensates for the threshold voltage Vth13 unique to the thin film transistor Tr13 of each display pixel PX (light emission drive circuit DC), and is applied by the precharge voltage Vpre. Threshold between the gate and source (both ends of capacitor Cs) It is set to a voltage value that can hold the voltage component corresponding pressure Vth 13.

  More specifically, the threshold voltage Vth13 of the thin film transistor Tr13 is described. As described above, n-channel amorphous silicon thin film transistors are applied as the thin film transistors Tr11 to Tr13 constituting the light emission drive circuit DC provided in the display pixel PX. In this case, the already established amorphous silicon manufacturing technique can be applied to form a thin film transistor with uniform element characteristics, and a light emission driving circuit with stable operating characteristics can be manufactured with a relatively simple manufacturing process. Has the advantage.

  However, it is known that, in an amorphous silicon thin film transistor, in general, a threshold voltage variation (Vth shift) due to a driving history occurs remarkably. As a drive control method for suppressing the influence of such threshold voltage fluctuations, as will be described later, the light emission drive circuit DC provided in the display pixel PX has a level corresponding to the display data via the data line DL. There is known a drive control method of a current gradation designation method (or current gradation designation drive) in which a current component (gradation current) of a modulation signal is directly flowed. In addition to the gate-source of the thin film transistor Tr13 (both ends of the capacitor Cs), the capacitance component (parasitic) formed in the path to which the gradation current is supplied is also charged to a predetermined voltage by the gradation current. Therefore, in particular, when a light emission operation (low gradation display) is performed at a low luminance gradation, the above-described charging operation takes time due to a small gradation current, and the gradation signal is not generated within a predetermined time. Write operation is completed In other words, insufficient writing occurs in which the voltage component held between the gate and source of the thin film transistor Tr13 (both ends of the capacitor Cs) is insufficient for the display data, and the light emission operation at a desired luminance gradation is not performed. there is a possibility.

  More specifically, in the current gray scale designation type drive control method, a thin film transistor required for flowing a gray scale current corresponding to display data between the drain and source of the thin film transistor Tr13 during a write operation to be described later. Many voltage components of the gate-source voltage Vgs of Tr13 contribute to the threshold voltage Vth13 of the thin film transistor Tr13. In particular, the organic EL element OEL emits light at the lowest luminance gradation (LSB). In the gate-source voltage Vgs (= Vlsb) of the thin film transistor Tr13 required for the generation, the ratio of the voltage component contributing to the threshold voltage Vth13 out of the held voltage component (total charge) is larger by 50%. As a result of various experiments by the inventors of the present application, it has been found that the value exceeds the limit.

  A voltage component (charge amount) corresponding to the threshold voltage Vth13 is written in a gradation signal (a gradation current having a minute current value) without applying the precharge operation (application of the precharge voltage Vpre). If an attempt is made to charge the gate-source (capacitor Cs) only by the loading operation, the writing operation period Twrt described later becomes significantly longer, and as a result, the image information is good for a predetermined processing period (frame period). There was a possibility that a bug that disappeared from the screen occurred.

  In view of this, in the display driving device applicable to the display device according to the present invention, the precharge period Tth is provided and the precharge voltage Vpre is applied prior to the gradation signal writing operation described later, whereby the thin film transistor Tr13. Between the gate and the source (both ends of the capacitor Cs), the current threshold voltage of the thin film transistor Tr13 (threshold voltage at the time of threshold voltage detection operation after Vth shift by the driving history) Vth13 equivalent voltage Even when a small gradation current at the time of low gradation display is set in a state in which the component is retained, a threshold voltage Vth13 equivalent is generated between the gate and source of the thin film transistor Tr13 (both ends of the capacitor Cs) by the gradation signal. Without charging the voltage component, the voltage component according to the display data (except for the threshold voltage Vth13 equivalent, the gradation table according to the display data) Only the substantial voltage component for illustration (effective voltage Vdata) can be added to the voltage component corresponding to the threshold voltage Vth13 and held between the gate and source of the thin film transistor Tr13.

  During the precharge period Tth, the voltage component corresponding to the threshold voltage Vth13 inherent to the thin film transistor Tr13 is controlled between the gate and the source of the thin film transistor Tr13, so that the drain of the thin film transistor Tr13 is drained. -Almost no current flows between the sources, and the potential on the anode terminal (contact N12) side of the organic EL element OEL is equal to or less than the common voltage Vcom on the cathode terminal side. Therefore, no voltage or reverse bias voltage is applied to the organic EL element OEL, and the organic EL element OEL does not emit light.

  In this way, in order to hold a voltage component corresponding to the threshold voltage Vth13 between the gate and source of the thin film transistor Tr13, a current based on the voltage component is not supplied to the light emission drive circuit DC and the data line DL, and each thin film transistor Tr13 is supplied. Since the precharge voltage Vpre having a voltage value corresponding to the inherent threshold voltage Vth13 is directly applied to the source terminal (contact N12) side of the thin film transistor Tr13, each display pixel PX (light emission drive circuit DC). The light emission driving thin film transistor Tr13 (capacitor Cs) can be quickly charged with a voltage component corresponding to the threshold voltage Vth13.

(Write operation period)
Next, in the write operation period Twrt after the end of the precharge period Tth, as shown in FIGS. 7 and 9, an on-level selection signal Ssel is applied to the selection line SL, and a low potential is applied to the supply voltage line VL. When the input selection switch 182 is switched to the gradation signal generation unit 130 in a state where the supply voltage Vsc (= Vs) is applied and the switching control signal AZ is set to the high level, the display data depends on the display data. The gradation signal (negative gradation current Idata) output from the gradation signal generation unit 130 is connected to the data line via the data line input / output switching unit 180 (input selection switch 182 and writing side switch 183). Supplied to DL. Here, as the gradation signal, a negative gradation current Idata is supplied, and the current is drawn from the data line DL side toward the gradation signal generation unit 130 via the data line input / output switching unit 180. It flows like

  As a result, the thin film transistor Tr11 provided in the display pixel PX (light emission drive circuit DC) is turned on, and the low-potential supply voltage Vsc (= Vs) is connected to the gate of the thin film transistor Tr13 and one end side of the capacitor Cs via the thin film transistor Tr11. When the thin film transistor Tr12 is turned on and the gradation current Idata is drawn through the data line DL, a voltage lower than the supply voltage Vsc is applied to the source of the thin film transistor Tr13. Since it is applied to the terminal side (contact N12; the other end of the capacitor Cs), the thin film transistor Tr13 is turned on in a predetermined conduction state, and as shown in FIG. 9, from the supply voltage line VL, the thin film transistor Tr13, the contact N12, Thin film transistor Tr12, data line D Via the display drive apparatus 100 (the gradation signal generation unit 130), the write current Iwrt which corresponds to the current value of the gradation current Idata flows quickly.

  Here, in the capacitor Cs connected between the gate and the source of the thin film transistor Tr13, a voltage component corresponding to the threshold voltage Vth13 unique to the thin film transistor Tr13 is held (charge is accumulated) in the above-described precharge period Tth. Therefore, the charge of the capacitance required for the write current Iwrt based on the gradation current Idata to be stabilized between the drain and source of the thin film transistor Tr13 does not include the threshold voltage Vth13, and is displayed. A gray-scale current Idata (write current Iwrt) having a current value for charging only the effective voltage Vdata for gray-scale display according to data may be used, and between the gate and source of the thin film transistor Tr13 in a relatively short time. The electric charge can be charged to both ends of the capacitor Cs.

  Therefore, even when the threshold voltage Vth13 of the thin film transistor Tr13 is Vth shifted due to a change with time, light emission history (driving history), etc., the voltage component Vdata corresponding to the gradation signal (display data) is written. It is possible to write quickly and sufficiently in the period Twrt. In this write operation period Twrt, the gate-source voltage Vgs of the thin film transistor Tr13, that is, the amount of charge accumulated in the capacitor Cs, is uniquely determined by the drain-source current (write current Iwrt) of the thin film transistor Tr13. Therefore, the voltage Vc charged in the capacitor Cs is specifically the sum of the threshold voltage Vth13 inherent to the thin film transistor Tr13 and the voltage component (effective voltage) Vdata corresponding to the gradation current Idata (Vth13 + Vdata). It becomes.

  At this time, a low-potential supply voltage Vsc (= Vs) is applied to the supply voltage line VL, and the write current Iwrt is supplied from the supply voltage line VL to the data line DL through the light emission drive circuit DC. Since it is controlled to flow, the potential applied to the anode terminal (contact N12) of the organic EL element OEL is equal to or lower than the potential Vcom (GND) of the cathode terminal, so that a reverse bias voltage is applied to the organic EL element OEL. As a result, no light emission drive current flows through the organic EL element OEL, and no light emission operation is performed.

(Light emission operation period)
Next, in the light emission operation period Tem after the end of the write operation period Twrt, as shown in FIGS. 7 and 10, an off level (low level) selection signal Ssel is applied to the selection line SL, and the supply voltage line VL is applied. A high potential supply voltage Vsc (= Ve) is applied. In synchronism with this timing, the gradation signal generator 130 stops the gradation current Idata drawing operation.

  Thereby, the thin film transistors Tr11 and Tr12 provided in the light emission drive circuit DC are turned off, and the supply voltage Vsc to the gate terminal (contact N11; one end side of the capacitor Cs) and the drain terminal of the thin film transistor Tr13 is cut off. At the same time, since the electrical connection between the data line DL and the source terminal of the thin film transistor Tr13 (contact N12; the other end of the capacitor Cs) is cut off, the charge accumulated in the capacitor Cs during the write operation period Twrt described above. Retained.

  Note that, during the light emission operation period Tem, the high-potential supply voltage Vsc (= Ve) applied to the supply voltage line VL is an anode necessary for causing the organic EL element OEL to perform light emission operation at the maximum luminance gradation (MSB). The voltage value is set to be equal to or higher than the voltage (a positive voltage that is forward biased with respect to the voltage Vcom connected to the cathode side of the organic EL element OEL).

Specifically, the high-potential supply voltage Vsc (= Ve) is set to a voltage value that satisfies the following expression (2).
| Ve-Vcom |> Vdsmax + Velmax (2)
In the above equation (2), Vdsmax is the light emitting operation period Tem between the drain and source of the thin film transistor Tr13 in the saturation region shown in FIG. The maximum voltage value between the drain and source of the thin film transistor Tr13 is reached. Velmax is a partial pressure of the organic EL element OEL at the maximum luminance gradation.

  As described above, the sum (Vth13 + Vdata) of the voltage components charged in the capacitor Cs during the precharge operation and the write operation is held as the potential Vc across the capacitor Cs, whereby the gate-source voltage Vgs (ie, the thin film transistor Tr13). , The potential of the contact N11) is held, and the thin film transistor Tr13 maintains the ON state.

  Therefore, during the light emission operation period Tem, as shown in FIG. 10, the light emission drive current Iem flows from the supply voltage line VL to the organic EL element OEL through the thin film transistor Tr13 and the contact N12, and the organic EL element OEL is driven to emit light. Light is emitted at a predetermined luminance gradation corresponding to the current value of the current Iem. Here, the charge (both-end potential Vc) held in the capacitor Cs during the light emission operation period Temp corresponds to the potential difference when the write current Iwrt corresponding to the gradation current Idata is passed through the thin film transistor Tr13 as described above. The light emission drive current Iem flowing through the organic EL element OEL has a current value (Iem≈Iwrt = Idata) equivalent to the write current Iwrt (gradation current Idata). As a result, the light emission drive current Iem corresponding to the predetermined light emission state (luminance gradation) is supplied based on the voltage component (effective voltage Vdata) written in the write operation period Twrt, and the organic EL element The OEL continuously emits light at a luminance gradation corresponding to display data (gradation signal).

  Thus, according to the display driving device and the display pixel applicable to the display device according to the present invention, the voltage component corresponding to the threshold voltage Vth13 is held between the gate and the source of the thin film transistor Tr13 in the precharge period, During the writing operation period, a gradation current Idata (writing current Iwrt) in which a current value corresponding to the light emission state (luminance gradation) of the organic EL element OEL is forcibly passed between the drain and the source of the thin film transistor Tr13, By holding the voltage component Vdata corresponding to the current value between the gate and source of the thin film transistor Tr13, the organic EL element (light emitting element) is substantially based on the voltage component (effective voltage Vdata) corresponding to the gradation current Idata. ) Applying a drive control method of a current gradation designation method in which the light emission drive current Iem flowing to the OEL is controlled to perform light emission operation at a predetermined luminance gradation, A function (current / voltage conversion function) for converting the current level of the gradation current Idata according to desired display data (luminance gradation) into a voltage level by using one light emission driving switching element (thin film transistor Tr13), and organic Since both the function of supplying the light emission drive current Iem having a predetermined current value to the EL element OEL (light emission drive function) is realized, variations in element characteristics among the thin film transistors constituting the light emission drive circuit DC and changes over time are realized. It is possible to stably realize desired light emission characteristics over a long period of time without being affected.

  Further, according to the display drive device and the display pixel applicable to the display device according to the present invention, prior to the display data (gradation signal) writing operation to the display pixel PX and the light emitting operation of the organic EL element OEL. Then, by performing the precharge operation, the precharge voltage Vpre is applied to the capacitor Cs connected between the gate and source terminals of the light emission driving thin film transistor Tr13 provided in each light emission drive circuit DC. The voltage component corresponding to the threshold voltage Vth13 unique to Tr13 can be set to be held (charge is accumulated).

  Therefore, the threshold voltage Vth13 of the light emission driving switching element (thin film transistor Tr13) provided in each display pixel PX (light emission drive circuit DC) has changed (Vth shift) due to changes over time, drive history, or the like. Even in this case, in the above-described precharge operation, it is possible to set a state in which charges corresponding to the threshold voltage Vth13 unique to each thin film transistor Tr13 are appropriately accumulated. Thereby, in the display data writing operation, it is not necessary to charge the capacitor Cs to the threshold voltage Vth13 by the gradation current Idata based on the display data, and the voltage component (brightness gradation) corresponding to the display data (luminance gradation). Effective voltage) Since only Vdata needs to be charged, the charge based on the display data can be quickly accumulated in the capacitor Cs, and the occurrence of insufficient writing can be suppressed, and the appropriate luminance corresponding to the display data can be obtained. The organic EL element OEL can be caused to emit light with gradation.

  In the display drive device described above, in the threshold voltage detection operation performed prior to the display drive operation, the light emission drive circuit DC (on the source terminal side of the thin film transistor Tr13) of each display pixel PX is supplied during the voltage application period Tpv. The configuration and drive control method of the display driving device in which the detection voltage Vpv to be applied is applied from the compensation voltage DAC 150 to the data line DL via the input selection switch 182 and the write side switch 183 have been shown. For example, as shown below, a dedicated power supply for applying the detection voltage Vpv to the data line DL may be provided.

FIG. 11 is a main part configuration diagram showing another configuration example of the display driving device applicable to the display device according to the present invention. Here, the description of the same configuration as the above-described display driving device is omitted.
As shown in FIG. 11, the display driving device according to the present configuration example includes a detection voltage Vpv that is output separately from the compensation voltage DAC 150 in addition to the configuration of the display driving device 100 described above (see FIG. 1). The input selection switch 182 provided in the data line input / output switching unit 180 includes a compensation voltage DAC 150 (precharge voltage Vpre) and a gradation signal generation unit 130 (gradation current Idata). In addition, one of the three components including the detection voltage power source 190 (detection voltage Vpv) can be selectively connected to the data line DL.

  According to this, in the voltage application period Tpv described above, an arbitrary voltage value is obtained only by controlling the input selection switch 182 and the write side switch 183 of the data line input / output switching unit 180 to the detection voltage power supply 190 side. Since the detection voltage Vpv can be applied to the data line DL, the processing load for the output operation of the detection voltage Vpv in the compensation voltage DAC 150 can be reduced.

(Display drive operation: Non-light emitting display operation)
Next, a driving control method in the case of performing non-light emitting display (black display) in which the light emitting element does not perform light emission in the display driving device and the display pixel having the above-described configuration will be described with reference to the drawings.

  FIG. 12 is a timing chart showing a drive control method (non-light emitting display operation) in a display drive device applicable to the display device according to the present invention. FIG. 13 is a conceptual diagram showing another example of the data writing operation in the display driving device applicable to the display device according to the present invention, and FIG. 14 is a display applicable to the display device according to the present invention. It is a conceptual diagram which shows the non-light-emission operation | movement in a drive device. Here, the description of the drive control equivalent to the gradation display operation described above is simplified or omitted.

  As shown in FIG. 12, the drive control operation (non-light emitting display operation) in the display drive device 100 described above is applied to each display pixel PX after the threshold voltage detection operation (threshold voltage detection period Tdec) described above. A voltage component corresponding to the threshold voltage Vth13 is held in the provided light emission driving thin film transistor Tr13 to compensate for the threshold voltage Vth13, and then a gradation signal (non-light emitting display voltage Vzero) corresponding to display data is generated. The display driving operation (display driving period) for writing and setting the organic EL element OEL to the non-light emitting state is included.

  In other words, in the drive control operation when performing the above-described gradation display operation, when shifting from the write operation period Twrt set during the display drive operation (display drive period Tcyc) to the light emission operation period Temp. The supply voltage Vsc is set so as to shift from the low potential (Vs) to the high potential (Ve). For this reason, a phenomenon occurs in which the potential (gate potential) applied to the gate terminal (contact N11) of the thin film transistor Tr13 rises due to the displacement of the charge held in the capacitive component parasitic on the thin film transistor Tr11.

  Here, when the luminance gradation based on the display data is the lowest gradation (black display state), the current value of the gradation current Idata is in a minute state or 0 (that is, the state in which the gradation current Idata does not flow). Since the voltage (both end potential Vc) charged in the capacitor Cs in the precharge period Tth is in the vicinity of the threshold voltage Vth13 unique to the thin film transistor Tr13, the write operation period Twrt to the light emission operation period Temp. Even if the gate potential fluctuates slightly due to the transition, the thin film transistor Tr13 is turned on and the light emission drive current Iem flows, and the non-light emission display (black display) operation corresponding to the display data is realized. There is a possibility that it will not be done (is unstable).

  In order to stabilize such a non-light emitting display operation, the voltage component (accumulated charge) charged in the capacitor Cs is discharged during the light emission operation period Tem, and the gate-source voltage Vgs (thin film transistor Tr13). The both-end potential Vc) of the capacitor Cs is set to be sufficiently lower than the threshold voltage Vth13 of the thin film transistor Tr13, more preferably 0V (that is, the contact N11 and the contact N12 are equipotential). It is desirable.

  In order to realize such a voltage state, when the writing operation is performed using the gradation current Idata having the minute current value as described above, the charge accumulated in the capacitor Cs is discharged to cause a gate-source connection. A relatively long time is required to set the voltage Vgs to a desired charge amount (voltage value). In particular, in the writing operation period Twrt of the previous display driving period (one processing cycle period) Tcyc, the closer the voltage component (both end potential Vc) charged to the capacitor Cs is to the maximum luminance gradation voltage, Since the amount of stored charge is large, it takes a longer time to discharge the charge to a desired voltage value.

  Therefore, in the display driving device applicable to the display device according to the present invention, as shown in FIG. 1, the gradation signal generation unit 130 has an organic EL element (light emitting element) with a predetermined luminance gradation corresponding to display data. ) In addition to means for generating and supplying the gradation current Idata for causing the OEL to emit light, a non-emission display voltage Vzero for causing the darkest display (black display) operation without causing the organic EL element OEL to emit light is provided. A means for generating and supplying is provided, and the non-light emitting display voltage Vzero is applied to the data line DL at the lowest luminance gradation (black display state).

  Here, the case where the gradation signal generation unit 130 applies the non-light emission display voltage Vzero to the light emission drive circuit DC (source terminal side of the thin film transistor Tr13; contact N12) via the data line DL is shown. However, the present invention is not limited to this, and for example, a dedicated power source for applying the non-light emitting display voltage Vzero to the data line DL may be provided.

  Then, the drive control method in the display drive device having such a configuration is as shown in FIG. 12, in the display drive operation after the above-described threshold voltage detection operation, as shown in FIG. During a period Tcyc, a predetermined precharge voltage Vpre is applied to the display pixel PX, and the thin film transistor is connected between the gate and the source of the light emitting driving thin film transistor Tr13 (both ends of the capacitor Cs) provided in the light emitting driving circuit DC. In accordance with a precharge period (compensation voltage application step) Tth in which a voltage component corresponding to the threshold voltage Vth13 unique to Tr13 is held (charge is accumulated or discharged in the capacitor Cs) and display data (non-emission display data) Applied to the display pixels PX (light emission drive circuit DC) via the data line DL. A writing operation period (data writing step) in which substantially all of the electric charge held between the gate and source of the thin film transistor Tr13 (capacitor Cs) is discharged to set the gate-source voltage Vgs of the thin film transistor Tr13 to 0V. It is set to include Twrt and a light emission operation period Tem in which the organic EL element OEL does not perform light emission operation (no light emission operation) (Tcyc ≧ Tth + Twrt + Tem).

  That is, in the precharge operation prior to the writing operation period Twrt, the gate-source (capacitor Cs) of the thin film transistor Tr13 for driving light emission is connected in the same manner as the drive control operation when executing the gradation display operation described above. After the voltage component corresponding to the threshold voltage Vth13 inherent to the thin film transistor Tr13 is held (charge amount is accumulated), in the gradation signal writing operation, as shown in FIG. The generation unit 130) supplies, for example, a low potential supply voltage Vsc (= Vs) and a non-light emitting display voltage Vzero that is equipotential to the display pixel PX (light emission driving circuit) via the data line input / output switching unit 180 and the data line DL. DC) is directly applied to the source terminal side (contact N12) of the thin film transistor Tr13 provided to the gate-source voltage Vgs (capacitor). s both ends potential Vc) of the set to 0V.

  In this way, almost all of the electric charge accumulated in the capacitor Cs is discharged, and the gate-source voltage Vgs of the thin film transistor Tr13 becomes a voltage value (substantially 0 V) sufficiently lower than the threshold voltage Vth13 inherent to the thin film transistor Tr13. Therefore, when the write operation period Twr is shifted to the light emission operation period Temp, the supply voltage Vsc is displaced from the low potential (Vs) to the high potential (Ve), and the gate potential of the thin film transistor Tr13 (the potential of the contact N11). 14), the thin film transistor Tr13 does not perform the on operation (holds the off state), and the light emission drive current Iem is not supplied to the organic EL element OEL, as shown in FIG. Not performed (becomes a non-light emitting state).

  As a result, during the non-light emitting display operation, the gradation current corresponding to the non-light emitting display data is supplied via the data line DL, and almost the electric charge accumulated in the capacitor Cs connected between the gate and the source of the thin film transistor Tr13. Compared to the case where all are discharged, it is possible to satisfactorily realize the non-light-emitting state (non-light-emitting display operation) of the organic EL element OEL while shortening the time required for writing the non-light-emitting display data. Therefore, in addition to the display driving operation for performing the normal gradation display described above, the display driving operation for performing the non-light emitting display is switched and controlled in accordance with the display data (luminance gradation data), so that the desired display operation can be performed. The light emission operation with the number of gradations (for example, 256 gradations) can be realized with relatively high brightness and clarity.

  In the display pixel PX described above, as shown in FIG. 1, an n-channel amorphous silicon thin film transistor is applied as the thin film transistors Tr11 to Tr13 provided in the light emission drive circuit DC. A silicon thin film transistor may be applied, or a p-channel amorphous silicon thin film transistor may be applied. Here, when the p-channel type is applied to all, the on level (high level) and off level (low level) of the signal are set to be inverted.

  Further, in the display pixel PX described above, as shown in FIG. 1, the light emitting drive circuit DC provided in each display pixel PX has been described with a circuit configuration including three thin film transistors Tr11 to Tr13. The present invention is not limited to this. That is, a light emission driving circuit corresponding to the current gradation designation method, using a single thin film transistor, converting a gradation current supplied according to display data into a voltage component and connecting between the gate and the source To realize a current / voltage conversion function that accumulates in a capacitor or parasitic capacitance, and a light emission drive function that controls a light emission drive current supplied to a light emitting element (organic EL element) based on the accumulated voltage component. Needless to say, other circuit configurations may be used.

  Further, in the drive control method for the display driving device described above, as a precharge operation, a precharge voltage Vpre having a voltage value based on the threshold value compensation data is applied to each display pixel PX from the compensation voltage DAC 150 via the data line DL. However, the present invention is not limited to this. In short, the gate of the light emission driving thin film transistor Tr13 provided in the light emission driving circuit DC of each display pixel PX by the precharge operation is described. A voltage component that compensates the threshold voltage of the drain-source current Ids of each thin film transistor Tr13 (a voltage component corresponding to the threshold voltage Vth13 unique to the thin film transistor Tr13) can be held between the sources. Therefore, for example, the threshold value compensation data is displayed from the display driving device 100. The precharge current having a current value based on, may have a structure to be applied through the data line DL in each display pixel PX.

<Display device>
Next, a display device and a drive control method thereof according to the present invention will be described with reference to the drawings.
FIG. 15 is a schematic block diagram showing an example of the overall configuration of the display device according to the present invention, and FIG. 16 shows a display panel and peripheral circuits (selection driver, power driver) applied to the display device according to the present invention. It is a schematic block diagram which shows an example. Here, configurations equivalent to those of the display drive device and the display pixel (light emission drive circuit) described above will be described with reference to the above-described drawings by attaching the same or equivalent reference numerals.

  As shown in FIG. 15 and FIG. 16, the display device 200 according to the present invention generally includes a plurality of selection lines (selection lines) SL arranged in the row direction and a plurality of data lines (selected lines) arranged in the column direction. A plurality of display pixels PX having a light emission driving circuit DC and an organic EL element (light emitting element) OEL having a circuit configuration equivalent to that of the above-described display pixel are arranged in the vicinity of each intersection with the data line DL. n and m are arbitrary positive integers) and are connected to a display panel 210 arranged in a matrix and a selection line SL of the display panel 210, and a selection signal Ssel at a predetermined timing sequentially for each selection line SL. Is connected to a selection driver (selection drive unit) 220 for applying voltage and a supply voltage line VL arranged in the row direction in parallel with each of the selection lines SL, and sequentially for each supply voltage line VL at a predetermined timing. A power supply driver (power supply driving unit) 230 that applies a supply voltage Vsc of a constant voltage level is connected to the data line DL of the display panel 210, and the threshold voltage detection period Tdec described above is passed through each data line DL. The threshold voltage at the time of the switching element (thin film transistor) for driving light emission provided in the display pixel PX (light emission driving circuit DC) of each column is detected, and at the display driving period Tcyc via each data line DL. Then, after applying a precharge voltage Vpre corresponding to a threshold voltage specific to the switching element of the display pixel PX to the display pixels PX of each column, a grayscale signal (grayscale current Idata, Alternatively, a timing supplied from a data driver (data driving unit) 240 that supplies a non-light emitting display voltage Vzero) and a display signal generation circuit 260 described later. System controller (drive) that generates and outputs at least a selection control signal, a power supply control signal, and a data control signal (timing control signal) for controlling the operation state of the selection driver 220, the power supply driver 230, and the data driver 240 based on the signal Control unit) 250, for example, based on a video signal supplied from the outside of the display device 200, display data (luminance gradation data) composed of a digital signal is generated and supplied to the data driver 240, and the display data And a display signal generation circuit 260 that extracts or generates a timing signal (system clock or the like) for displaying predetermined image information on the display panel 210 and supplies the timing signal to the system controller 250. ing.

Hereafter, each said structure is demonstrated concretely.
(Display panel)
Each of the display pixels PX arranged in the display panel 210 shown in FIG. 16 is a selection signal applied from the selection driver 220 via the selection line (selection line) SL, similarly to the display pixel (see FIG. 1) described above. Ssel, a supply voltage Vsc applied from the power supply driver 230 via the supply voltage line VL, and a gradation signal supplied from the data driver 240 via the data line (data line) DL (gradation current Idata or A light emission drive circuit DC that generates a light emission drive current Iem according to display data based on the non-light emission display voltage Vzero), and a predetermined luminance according to the current value of the light emission drive current Iem supplied from the light emission drive circuit DC And an organic EL element (light emitting element) OEL that emits light with gradation. Here, similarly to the display pixel described above, the light emitting element is another light emitting element as long as it is a current control type light emitting element that performs a light emitting operation at a predetermined luminance gradation in accordance with the current value of the light emission driving current. May be.

(Selected driver)
The selection driver 220 applies an on-level (high level in the above-described display pixel) selection signal Ssel to each selection line SL based on a selection control signal supplied from the system controller 250, thereby The display pixel PX is set to the selected state. Specifically, for the display pixels PX in each row, the selection signal Ssel is applied to the row during the period of performing the threshold voltage detection operation and the display drive operation (precharge operation and writing operation) excluding the light emission operation. By sequentially executing the operation applied to the selection line SL for each row at a predetermined timing, the display pixels PX for each row are sequentially set to the selected state.

  Here, for example, as shown in FIG. 16, the selection driver 220 corresponds to the selection line SL of each row based on a selection clock signal SCK and a selection start signal SST supplied as a selection control signal from a system controller 250 described later. A known shift register 221 that sequentially outputs shift signals to be output, and an output supplied as a selection control signal from the system controller 250 by converting the shift signal output from the shift register 221 to a predetermined signal level (on level) An output circuit unit (output buffer) 222 that outputs a selection signal Ssel to each selection line SL based on the control signal SOE is provided.

(Power supply driver)
Based on the power supply control signal supplied from the system controller 250, the power supply driver 230 applies the high potential supply voltage Vsc (= Ve) to the supply voltage line VL of the row for the display pixels PX of each row only during the light emission operation period. The low-potential supply voltage Vsc (= Vs) is applied during the operation period other than the light emission operation period (the threshold voltage detection period Tdec and the precharge period Tth and the write operation period Twrt in the display drive period Tcyc). Apply.

  Here, for example, as shown in FIG. 16, the power supply driver 230 is based on the clock signal VCK and the start signal VST supplied as the power supply control signal from the system controller 250, as in the selection driver 220 described above. A known shift register 231 that sequentially outputs a shift signal corresponding to the supply voltage line VL, and an output control signal VOE that is converted into a predetermined voltage level (voltage values Ve and Vs) and is supplied as a power control signal. And an output circuit section 232 for outputting the supply voltage Vsc to each supply voltage line VL.

(Data driver)
Similarly to the display driving apparatus 100 described above, the data driver 240 includes at least the shift register / data register unit 110, the display data latch unit 120, the gradation signal generation unit 130, the detection voltage ADC 140, and the like illustrated in FIG. , A compensation voltage DAC 150, a threshold data latch unit 160, a frame memory 170, and a data line input / output switching unit 180.

  Although FIG. 1 shows a configuration corresponding to a single display pixel PX, in the data driver 240 applied to the display device 200 according to the present invention, each array arranged in the column direction of the display panel 210. The data line input / output switching unit 180 is provided for each data line DL, and the voltage detection side switch 181, the input selection switch 182 and the write side switch 183 constituting the data line input / output switching unit 180 are controlled as described above. By performing switching control based on the method, the detection voltage Vpv, the precharge voltage Vpre, and the gradation signal (gradation current Idata) are simultaneously or concurrently applied to the display pixels PX in each row. , A non-light emitting display voltage Vzero) or an operation of measuring the detection voltage Vdec is selectively executed.

In other words, the shift register / data register unit 110 provided in the data driver (display driving device) 240 is configured so that each row corresponds to one row based on a data control signal (shift clock signal, sampling start signal) supplied from the system controller 250. Based on the output timing of the shift signal generated corresponding to the display pixel PX of the column (or the data line DL of each column), the display data for one row supplied from the display signal generation circuit 260 is sequentially fetched.
Based on the data control signal (data latch signal), the display data latch unit 120 transfers the display data for one row taken in by the shift register / data register unit 110, and displays the data for each display pixel PX in each column. Retained.

  The gradation signal generation unit 130 is based on each display data held in the display data latch unit 120, and the gradation current Idata having a current value corresponding to the display data or the non-light emission having a predetermined voltage value. A display voltage Vzero is generated and applied to each data line DL simultaneously (in a lump) or sequentially as a gradation signal.

  Specifically, in the case where the display data is gray scale display data for performing normal gray scale display accompanied by the light emission operation of the organic EL element (light emitting element) OEL, for example, a predetermined value based on the gray scale reference voltage is used. Is converted into an analog signal voltage having a voltage value (digital-analog conversion processing), and further, a gradation current Idata having a current value corresponding to the display data is generated (voltage-current conversion processing), and a predetermined timing is obtained. When the display data is non-light-emitting display data not accompanied by the light-emitting operation of the organic EL element (light-emitting element) OEL, a predetermined non-light-emitting display voltage Vzero is set to a predetermined value. Output to the data line DL of the column at the timing.

  The non-light emission display voltage Vzero is a light emission driving switching provided in the light emission drive circuit DC constituting the display pixel PX by the precharge operation as shown in the drive control method (non-light emission display operation) described above. Electric charges accumulated between the gate and source (capacitor Cs) of the element (thin film transistor Tr13) are discharged, and the gate-source voltage Vgs (potential Vc across the capacitor Cs) is set to 0V (or approximated to 0V). ) Is set to any voltage value necessary for. Here, the non-light emitting display voltage Vzero and the gradation reference voltage for generating the gradation current Idata are supplied from, for example, power supply means (not shown).

  The detection voltage ADC 140 is a display pixel PX (light emission drive) in each column of the row set to the selected state in the threshold voltage detection operation prior to the display operation of the image information on the display panel 210 (display drive operation of the display pixel PX). The threshold voltage (or voltage component corresponding to the threshold voltage) at the time of execution of the threshold voltage detection operation of the switching element (thin film transistor Tr13) for driving light emission provided in the circuit DC) is The detection voltage Vdec is measured in parallel or sequentially through each data line DL, converted into threshold detection data composed of a digital signal voltage, and output to the threshold data latch unit 160.

  The compensation voltage DAC 150 is used for the display pixel PX (light emission drive) in each column of the row set to the selected state in the threshold voltage detection operation prior to the display operation of the image information on the display panel 210 (display drive operation of the display pixel PX). A predetermined detection voltage Vpv is simultaneously output in parallel or sequentially to each of the light emission driving switching elements provided in the circuit DC via the data lines DL.

  Further, the compensation voltage DAC 150 is specific to the switching element provided in the display pixel PX in each column of the row set in the selected state in the display operation of the image information on the display panel 210 (display drive operation of the display pixel PX). A precharge voltage Vpre is generated based on threshold compensation data for compensating the threshold voltage of the pixel, and is output to the display pixels PX in each column in parallel or sequentially via each data line DL. .

  The threshold data latch unit 160 is a display pixel in each column of the row set to the selected state in the threshold voltage detection operation prior to the display operation of the image information on the display panel 210 (display drive operation of the display pixel PX). For each PX, after the threshold detection data converted and generated by the detection voltage ADC 140 is captured and held, the threshold detection data for one row is extracted by the shift register / data register unit 110, and the frame The data is sequentially transferred to the memory 170.

  Further, the threshold data latch unit 160 is a selection state sequentially taken out from the frame memory 170 by the shift register / data register unit 110 in the display operation of the image information on the display panel 210 (display drive operation of the display pixel PX). The threshold compensation data corresponding to the threshold detection data for each display pixel PX in each column of the set row is captured and held, and transferred to the compensation voltage DAC 150 for each column.

(System controller)
The system controller 250 generates and outputs a selection control signal, a power supply control signal, and a data control signal for controlling the operation state to each of the selection driver 220, the power supply driver 230, and the data driver 240, thereby outputting each driver. By operating at a predetermined timing, a selection signal Ssel having a predetermined voltage level, a supply voltage Vsc, and a gradation signal (gradation current Idata, non-light emitting display voltage Vzero) are generated and output, and each display pixel PX ( Video signal by causing threshold voltage detection operation (voltage application operation, voltage convergence operation, voltage reading operation) and display drive operation (precharge operation, writing operation, light emission operation) in the light emission drive circuit DC) Control for displaying predetermined image information on the display panel 210 is performed. A specific control operation will be described in detail in a drive control method described later.

(Display signal generation circuit)
For example, the display signal generation circuit 260 extracts a luminance gradation signal component from a video signal supplied from the outside of the display device 200, and converts the luminance gradation signal component from a digital signal for each row of the display panel 210. Is supplied to the shift register / data register unit of the data driver 240 as display data (luminance gradation data). Here, when the video signal includes a timing signal component that defines the display timing of the image information, such as a television broadcast signal (composite video signal), the display signal generation circuit 260 displays the luminance gradation signal component. In addition to the function of extracting the timing signal component, the timing signal component may be extracted and supplied to the system controller 250. In this case, the system controller 250 generates control signals to be individually supplied to the selection driver 220, the power supply driver 230, and the data driver 240 based on the timing signal supplied from the display signal generation circuit 260. .

  15 and 16, the selection driver 220 connected to the selection line SL and the power supply driver 230 connected to the supply voltage line VL are individually provided around the display panel 210. As described in the drive control method (see FIGS. 7 and 12) of the display drive device (corresponding to the data driver 240) described above, the display pixels PX in a specific row are selected (selected). The selection signal Ssel applied to the selection line SL (from the driver 220) and the supply voltage Vsc applied to the supply voltage line VL (from the power supply driver 230) are set such that the signal levels are in an inverted relationship with each other. Therefore, when each display pixel PX arranged in the display panel 210 performs display drive operation (particularly, light emission operation) independently in units of rows (specifically, In the case of the first example of the drive control method of the display device 200 described below, the signal level of the selection signal Ssel generated by the selection driver 220 is inverted (level inversion processing), and further has a predetermined voltage level. In this way, by performing level conversion (level conversion processing) and applying the voltage to the supply voltage line VL of the row, a configuration without the power supply driver 230 can be applied.

<Display device drive control method>
Next, a drive control method (drive control operation) in the display device according to the present invention will be described.
FIG. 17 is a timing chart schematically showing a first example of the display device drive control method according to the present invention. Here, the description of the drive control method (see FIGS. 2 and 7) equivalent to that in the display drive device 100 and the display pixel PX (light emission drive circuit DC) described above is simplified. Here, for convenience of explanation, it is assumed that the display panel has a configuration in which display pixels of 12 rows (1st to 12th rows) are arranged for convenience.

  A first example of the drive control operation of the display device 200 according to the present invention is roughly arranged on the display panel 210 within one frame period (about 16.7 msec; constant operation period) as shown in FIG. For the display pixels in a specific row among the display pixels PX, the light emission drive switching element (thin film transistor; thin film transistor; which controls the light emission state of the organic EL element (light emission element) OEL in the light emission drive circuit DC provided in each display pixel PX. A threshold voltage detection operation (threshold voltage detection period Tdec) for detecting a threshold voltage (or a voltage component corresponding to the threshold voltage) of the light emission driving element), and each row of the display panel 210 For the display pixel PX (light emission drive circuit DC), after compensating the threshold voltage of the switching element (holding a voltage component corresponding to the threshold voltage), the display pixel PX Display drive for writing gradation signals (gradation current Idata, non-emission display voltage Vzero) and causing display pixels PX (organic EL elements OEL) in each row to emit light at a luminance gradation corresponding to the display data (gradation signal). The operation (display driving period Tcyc) is sequentially repeated for all rows, and image information for one screen of the display panel 210 is displayed.

Here, the threshold voltage detection operation (threshold voltage detection period Tdec) is the display pixel PX (light emission drive circuit DC) in a specific row of the display panel 210 as in the drive control method in the display drive device described above. In contrast, a voltage application operation (voltage application period Tpv) for applying a predetermined detection voltage Vpv, and a voltage component based on the detection voltage Vpv as a threshold value at the detection time of each switching element (thin film transistor Tr13). Voltage convergence operation (voltage convergence period Tcv) for converging to voltage and threshold voltage Vth13 after voltage convergence in each display pixel PX are measured (read) and stored as threshold detection data for each display pixel PX. A series of drive control including a voltage reading operation (voltage reading period) is executed.
In particular, in the drive control operation of the display device according to the first example, the threshold voltage composed of the above-described series of drive controls for a specific row of display pixels PX for each frame period in successive frame periods. The detection operation is executed sequentially.

  Specifically, as shown in FIG. 17, in the display panel 210 in which 12 rows of display pixels PX are arranged, the threshold voltage detection operation is performed on the first row of display pixels PX in the first frame. The threshold detection data is stored in the corresponding storage area of the frame memory. In the first frame, after the threshold voltage detection operation for the display pixel PX in the first row is completed, for all the display pixels PX arranged in the display panel 210, for each row from the first row to the twelfth row. Display drive operations described later are sequentially executed.

  Next, in the second frame, after the display drive operation is performed for the display pixels PX in the first row, the threshold voltage detection operation is performed for the display pixels PX in the second row, and the threshold detection data Are stored in the corresponding storage area of the frame memory. Thereafter, the display drive operation is sequentially executed for each row of the display pixels PX from the second row to the twelfth row of the display panel 210.

  Next, in the third frame, after the display drive operation is performed for the display pixels PX in the first row and the second row, the threshold voltage detection operation is performed for the display pixels PX in the third row. The threshold detection data is stored in the corresponding storage area of the frame memory. Thereafter, the display drive operation is sequentially executed for each row of the display pixels PX from the third row to the twelfth row of the display panel 210.

Similarly, the threshold voltage detection operation is sequentially repeated for the display pixels PX in the corresponding row up to the 12th frame, whereby all the display pixels PX arranged in one frame of the display panel 210 are displayed in the frame memory. Threshold data (threshold voltage) is stored.
That is, in the display device drive control method (threshold voltage detection operation) according to the present invention, the threshold voltage detection operation is executed for the display pixels PX in any row of the display panel 210 in each frame period. The latest threshold voltage is always detected (monitored) with the frame period for the number of rows of the display panel as one cycle.

  In the timing chart shown in FIG. 17, hatched portions in each row of the threshold voltage detection period Tdec indicate a series of thresholds including the above-described voltage application operation, voltage convergence operation, and voltage reading operation. The value voltage detection operation is shown, and the threshold voltage detection operation for each row is sequentially executed at different timings so as not to overlap in time.

  Further, the display drive operation (display drive period Tcyc) is applied to the display pixels PX (light emission drive circuit DC) for each row of the display panel 210 within one frame period, as in the drive control method in the display drive apparatus described above. On the other hand, threshold value detection data (threshold compensation data) detected for each row of display pixels PX (light emission driving switching elements) in each frame period by the threshold voltage detection operation and stored in the frame memory. ) Based on the precharge operation (precharge period Tth) for writing the precharge voltage Vpre that compensates the threshold voltage of each display pixel PX, and the grayscale signal (grayscale current Idata, no light emission) according to the display data Each of the writing operation (writing operation period Twrt) for writing display voltage Vzero) and the luminance gradation corresponding to the display data (gradation signal) at a predetermined timing A series of drive control including a light emission operation (light emission operation period Tem) for causing the display pixel PX (organic EL element OEL) to emit light is sequentially executed for each row at a predetermined timing.

  In particular, in the drive control operation of the display device according to the first example, the precharge operation and the write operation for each row are sequentially performed at different timings so as not to overlap in time, and the write operation is completed. The light emission operation is executed in order from the display pixel PX in the row. That is, among the display driving operations for each row, only the light emitting operation is executed so as to overlap each other in time (partially in parallel).

  Here, in the timing chart shown in FIG. 17, the hatched portions (indicated as “Tth + Twrt”) indicated by the cross mesh in each row of the display drive period Tcyc are pre-shown in the drive control method of the display drive operation described above. The charging operation and the writing operation are represented, and the dot hatched portion of each row represents the light emitting operation.

  Specifically, as shown in FIG. 17, in the precharge period Tth and the write operation period Twrt of the display driving operation (display driving period Tcyc), the selection driver 220 applies the selection line SL to each row of the display panel 210. As shown in FIGS. 7 and 12, the on-level (high level) selection signal Ssel is individually applied to sequentially set the display pixels PX in each row to the selected state. Further, in the precharge period Tth and the write operation period Twrt, the low potential supply voltage Vsc (= Vs) is applied from the power supply driver 230 to the supply voltage line VL of each row.

  Then, in synchronization with this timing (hereinafter, referred to as “selection timing” for the sake of convenience), the display pixel PX in the row set in the selected state is first provided in the data driver 240 in the precharge period Tth. An individual precharge voltage Vpre for compensating a threshold voltage of a switching element (thin film transistor) provided in each display pixel PX (light emission drive circuit DC) from the compensated compensation voltage DAC 150 to each data line DL. By applying the voltage to the control terminal of the switching element of each display pixel PX in the row (specifically, between the gate and source terminals of the thin film transistor Tr13; both ends of the capacitor Cs), the switching element (thin film transistor Tr13) is unique. A voltage component corresponding to the threshold voltage is held (charge is accumulated).

  Here, as described in the threshold voltage detection operation described above, the threshold voltage of the switching elements of the display pixels PX arranged in the display panel 210 is a specific one row of display pixels for each frame period. Since the drive is controlled so as to be detected with respect to PX, immediately after the system is started or immediately after the recovery from the hibernation state, the threshold voltage detected for the display pixel PX detected last time and stored in the frame memory is set. Based on this, the precharge operation is executed (precharge voltage Vpre is generated).

  Next, in the write operation period Twrt, each display pixel PX (light emission drive circuit DC) in the row set in the selected state is transferred from the gradation signal generation unit 130 provided in the data driver 240 to the data line DL in each column. By individually applying a grayscale signal (grayscale current Idata or non-light emitting display voltage Vzero) corresponding to the display data, the control terminal (specifically, the switching element of the display pixel PX in each column of the row) The voltage component corresponding to the gradation signal (display data) is held (charge is accumulated or discharged) between the gate and source terminals of the thin film transistor Tr13; both ends of the capacitor Cs.

  Here, as in the drive control method described above, the display data supplied from the display signal generation circuit 260 to the data driver 240 is gray scale display data (other than 0 bits) accompanied by the light emitting operation of the organic EL element (light emitting element) OEL. In the case of the gradation value; gradation display operation), the data driver 240 (gradation signal generation unit 130) generates the gradation current Idata corresponding to the display data and applies it to the display pixel PX in the corresponding column. On the other hand, when the display data is non-light-emitting display data (0-bit gradation value; non-light-emitting display operation) that does not involve the light-emitting operation of the organic EL element (light-emitting element) OEL, the data driver 240. Thus, a predetermined non-light emitting display voltage Vzero is generated and supplied to the display pixels PX in the corresponding column.

  Therefore, in the display pixel PX to which the gradation current Idata is supplied as the gradation signal, each display pixel PX (between the gate and the source of the light emitting driving thin film transistor) is charged by the above-described precharge operation. The voltage component (effective voltage Vdata) based on the gradation current Idata is charged by being added to the voltage component corresponding to the threshold voltage (Vth13).

  Further, in the display pixel PX to which the non-light emitting display voltage Vzero is supplied as the gradation signal, a voltage component corresponding to the threshold voltage (Vth13) charged in each display pixel PX in the row by the precharge operation described above. Almost all (charge) is discharged, and as a result, a voltage (0 V) corresponding to the display data is set in the switching element for driving light emission (between the gate and the source of the thin film transistor).

  Next, as shown in FIG. 17, in the light emission operation period Tem of the display drive operation (display drive period Tcyc), as shown in FIGS. 7 and 12, the selection driver 220 applies the selection line SL to each row. By applying an off-level (low-level) selection signal Ssel, each display pixel PX in each row is set to a non-selected state. In addition, application of the gradation signal to each data line DL from the gradation signal generation unit 130 provided in the data driver 240 is blocked.

  In synchronism with this timing, the supply voltage Vsc (= Ve) of the high potential is applied to the supply voltage line VL of the row set to the non-selected state from the power supply driver 230, thereby Based on the voltage component charged in each display pixel PX (between the gate and source of the light emission driving thin film transistor), the light emission drive current Iem corresponding to the display data (gradation signal) is supplied to the organic EL element OEL. The light emission operation or the non-light emission operation is performed at the luminance gradation.

  Here, when the gradation signal written in each display pixel PX is based on gradation display data (gradation value other than 0 bit) accompanied by the light emitting operation of the organic EL element OEL, the organic EL element OEL A light emission driving current Iem equivalent to the gradation current Idata is supplied, and the organic EL element OEL performs a light emission operation (gradation display operation) with a predetermined luminance gradation corresponding to the display data. When based on non-light emitting display data (0-bit gradation value) not accompanied by the light emitting operation of the organic EL element OEL, the light emitting drive current Iem is not supplied to the organic EL element OEL, and the light emitting operation is not performed ( Non-light emitting display operation; black display operation).

  Such a light emission operation (or no light emission operation) is started in synchronization with the end timing of the precharge operation and the write operation in the display pixels PX of each row (immediately after the end), Until the start timing (immediately before the start) of the charge operation and the write operation, for example, it is continuously executed for one frame period.

  In addition, in synchronization with the end timing of the precharge operation and the write operation for the display pixel PX of each row (for example, i row; 1 ≦ i ≦ 12) (immediately after the end), adjacent rows (i + 1 row) For the display pixel PX, a precharge operation and a write operation similar to the above are started. As described above, in the row (for example, the i-th row) in which the threshold voltage detection operation (threshold detection period Tdec) is executed, the previous row (i-1th row). ), After the precharge operation and the write operation are finished, the threshold voltage detection operation is executed for the row, and then the precharge operation and the write operation are executed.

  As a result, as shown in FIG. 17, within one frame period, the display pixels PX (light emission drive circuit DC) for each row of the display panel 210 are applied to each display pixel PX by the precharge operation and the write operation. The operation of charging the appropriate voltage component according to the display data (gradation signal) is executed sequentially at different timings so that the rows do not overlap each other in time, and the precharge operation and the write operation The drive control operation is executed in which the light emission operation (or the non-light emission operation) is sequentially performed with a predetermined luminance gradation from the display pixels PX in the row where the operation is completed so as to partially overlap each other in time.

  As described above, according to the first example of the display device and the drive control method thereof according to the present invention, the display drive device and the display pixel corresponding to the above-described drive control method of the current-designated gradation method are replaced with the data driver and the display pixel, respectively. By having a configuration applied to the display panel, during a normal gradation display operation (other than a non-light emitting display operation), a light emitting element (based on a current value of a gradation current corresponding to display data) The light emission drive current supplied to the organic EL element) can be controlled, and the current level of the gradation current is set to a voltage level by a single switching element (light emission drive thin film transistor) provided in each display pixel. Since the current value of the light emission drive current can be set based on the voltage level, the light emission drive switching element (light emission drive circuit) provided in each display pixel (light emission drive circuit) Without being affected by the variation or aging of the device characteristics of the film transistor) (threshold voltage), it can be achieved stably desired emission characteristics over a long period of time.

  Further, according to the display device and the drive control method thereof according to the present invention, the display data (gradation signal) writing operation to the display pixels in each row arranged in the display panel, and the light emitting element (organic EL element) Prior to the light emission operation, the threshold voltage of the light emission driving switching element (thin film transistor) provided in the display pixel (light emission drive circuit) is detected for the display pixels in a specific row for each frame period. (Threshold voltage detection operation) and then immediately before the write operation of the display data to each display pixel, the light emission driving switching element (thin film transistor) provided in the display pixel detects the above. By applying a precharge voltage corresponding to the threshold voltage (precharge operation), the threshold voltage detection operation is performed on the display pixels in any row arranged on the display panel. The threshold voltage (Vth shift state) of the switching element for light emission driving at the time of row can be constantly monitored, and the control terminal (between the thin film transistor gate and source) of the switching element for light emission driving of each display pixel. And a state in which a voltage component (charge) corresponding to a threshold voltage specific to the switching element (threshold voltage fluctuated by a Vth shift) is held (threshold voltage is individually compensated). Therefore, in the display data writing operation, only the voltage component corresponding to the display data needs to be added and charged, and the voltage component based on the display data can be written quickly and appropriately.

  Therefore, in the drive control method of the current gradation designation method, the voltage component corresponding to the display data can be quickly and quickly even in the display operation at the low luminance gradation where the gradation current corresponding to the display data becomes very small. Since writing can be performed appropriately, the occurrence of insufficient writing in each display pixel can be suppressed, and it is also affected by the Vth shift of the light emission driving switching element (thin film transistor) provided in each display pixel. Therefore, desired image information can be displayed satisfactorily over a long period of time with an appropriate luminance gradation according to the video signal.

  In the non-light-emitting display, a predetermined non-light-emitting display voltage corresponding to display data (0-bit gradation value) is supplied to each display pixel, whereby a switching element for driving light emission (gate-source of a thin film transistor). Can quickly discharge almost all of the voltage components held between them, so that the supply of the light emission drive current to the light emitting element (organic EL element) can be shut off reliably, and the non-light emitting display operation is stable. Can be realized.

  Furthermore, according to the drive control method according to the first example, in each row of the display panel, in one frame period other than the precharge period and the write operation period, the next precharge period and the write operation period. Since the drive control is performed so that the light emission operation continues until the start timing or the threshold voltage detection operation start timing, the light emission time of each display pixel (light emitting element) can be set to be sufficiently long. Information can be displayed with high luminance. In other words, this means that image information can be displayed with sufficient luminance even when the light emission luminance of each display pixel is reduced, and thus power consumption for displaying image information can be reduced. .

Next, a second example of the drive control method in the display device according to the present invention will be described with reference to the drawings.
FIG. 18 is a timing chart schematically showing a second example of the display device drive control method according to the present invention. Here, the description of the drive control method equivalent to the above-described first example (see FIG. 17) is simplified. In addition, the hatched portion in the figure shows an operation state equivalent to that of the first example described above. FIG. 19 is a main part configuration diagram showing an example of a display device for realizing a second example of the display device drive control method according to the present invention. Here, components equivalent to those of the display device described above will be described with the same reference numerals.

  As shown in FIG. 18, in the second example of the drive control operation of the display device 200 according to the present invention, first, the display pixels PX arranged on the display panel 210 are grouped in advance for each of a plurality of adjacent rows. Then, within one frame period, a threshold voltage detection operation (threshold voltage detection period) for detecting a threshold voltage with respect to a switching element (thin film transistor) for driving light emission of the display pixels PX in a specific row of a specific group Tdec) and the display pixels PX for each row of the display panel 210 are compensated for the threshold voltage, and then a gradation signal (gradation current Idata, non-light emitting display voltage Vzero) corresponding to the display data is written. The operation (precharge period Tth, write operation period Twrt) is sequentially repeated for all the rows, and a plurality of rows of display pixels PX (organic EL elements OE) for each group at a predetermined timing. By executing a display driving operation in which L) performs a light emission operation at the same time with the luminance gradation corresponding to the display data (gradation signal), image information for one screen of the display panel 210 is displayed.

  Here, specifically, in the drive control operation according to the second example, first, all the display pixels PX arranged in the display panel 210 are grouped in advance for each of a plurality of rows. For example, as shown in FIG. 18, 12 rows of display pixels PX constituting the display panel 210 are arranged in 4 rows such as the 1st to 4th rows, the 5th to 8th rows, and the 9th to 12th rows adjacent to each other. Minute display pixels PX are grouped as a set.

  Then, in the first frame, the threshold voltage detection operation (threshold voltage detection period Tdec) is executed for the display pixels PX in the first row in the group including the display pixels PX in the first to fourth rows. The threshold detection data is stored in the corresponding storage area of the frame memory. In the first frame, after the threshold voltage detection operation for the display pixel PX in the first row is completed, for all the display pixels PX arranged in the display panel 210, for each row from the first row to the twelfth row. Display drive operations (precharge operation and write operation; Tth + Twrt) are sequentially executed.

  In the display driving operation for each row, the light emitting operation is performed for the group in which the writing operation to the display pixels PX of all the rows included in each group is completed. For example, in a group in which the display pixels PX in the first to fourth rows are set as one set, the precharge operation and the writing operation are sequentially performed from the display pixels PX in the first row, and the display pixels PX in the fourth row are performed. At the timing when the writing operation is completed, the display pixels PX for the four rows in the group simultaneously emit light based on the display data (gradation signal) written to each display pixel PX. This light emission operation is performed at the timing when the next precharge operation and write operation are started for the display pixel PX in the first row, or the threshold voltage detection operation is performed for any one of the first to fourth rows. It continues until the start timing.

  In addition, at the timing when the writing operation is completed for the display pixels PX in the fourth row, the precharge is sequentially performed from the display pixels PX in the fifth row in a group including the display pixels PX in the fifth to eighth rows. When the operation and the writing operation are executed and the writing operation is finished for the display pixels PX in the eighth row, the display pixels PX for the four rows in the group simultaneously emit light. Thereafter, the same operation is repeatedly performed for the display pixels PX in each row of the next group.

  Next, in the second frame, the precharge operation and the write operation are sequentially executed in a group including the display pixels PX in the first to fourth rows as a set, and the display pixels PX for the four rows in the group emit light all at once. The threshold voltage detection operation (threshold value) for the display pixel PX in the fourth row (corresponding to the first row in the group) in the group of the display pixels PX in the fifth to eighth rows as a set at the timing of operation. After the value voltage detection period Tdec) is executed and the threshold voltage detection operation is completed, the precharge operation and the write operation are sequentially executed in the group.

  Next, the precharge operation and the write operation are completed in the group including the display pixels PX in the fifth to eighth rows as a set, and the display pixels PX in the four rows of the group are simultaneously turned on at a timing of 9 to A precharge operation and a write operation are sequentially executed in a group including the display pixels PX on the 12th row as a set, and thereafter, the display pixels PX for 4 rows in the group simultaneously perform a light emission operation.

  Similarly, for each frame period, a threshold detection operation is performed for display pixels PX in a specific row included in the group for each preset group, and all rows included in each group are also included. At the time when the writing operation to the display pixel PX is completed, the display driving operation for causing all the display pixels PX in the group to emit light at once is repeatedly executed.

  As described above, the threshold voltage detection operation is sequentially performed on the display pixels PX in a specific row for each frame period, so that the display pixels PX in any row of the display panel 210 are performed in each frame period. The threshold voltage detection operation is executed, and the latest threshold voltage is always detected (monitored) with one frame period corresponding to the number of rows of the display panel as one cycle.

  In the display driving operation according to the second example, during the period in which the threshold voltage detection operation, the precharge operation, and the writing operation are performed on the display pixels PX in other rows of the same group. Control is performed so that all the display pixels in the group are set to the non-light emitting display state (black display state) by performing the non-light emitting operation.

  For example, as shown in FIGS. 7 and 12, such a display driving operation is performed by the power supply driver 230 during the threshold voltage detection operation, the precharge operation, and the writing operation. A period during which the threshold voltage detection operation, the precharge operation, and the write operation are performed on the display pixels PX in the rows included in the same group using the low potential supply voltage Vsc (= Vs) applied to The threshold voltage detection operation, the precharge operation, and the write operation for all the rows included in the group are continuously applied to the supply voltage lines VL of all the rows in the group. This can be realized by controlling to apply a high-potential supply voltage Vsc (= Ve).

  Further, the same drive control is performed by branching a single supply voltage line VL, for example, as shown in FIG. 19 so that a single supply voltage Vsc is simultaneously applied to each group. A configuration in which the display pixels PX in the rows (or the 5th to 8th rows and the 9th to 12th rows) are connected in common is applied, and the single supply voltage Vsc applied from the power supply driver 230 is in the same group. It can also be realized by being applied to the display pixels PX in all the included rows. Also in this drive control method, as in the case shown in FIG. 16, individual selection lines SL are provided for each row of the display panel 210, and individual selection signals Ssel are applied from the selection driver 220 at different timings. Is done.

  Therefore, according to the drive control method (display drive operation) of such a display device, it is possible to obtain the same operation effect as the drive control method according to the first example described above, and display of each row in the same group. During the period when the threshold voltage detection operation, the precharge operation, and the writing operation are performed on the pixel, the light emission operation of the display pixel (light emitting element) is not performed, and the non-light emission operation (black display operation) is performed. When a moving image is displayed by continuous display of information (still image), flickering of the moving image can be suppressed and the sharpness can be improved.

  Here, in the timing chart shown in FIG. 18, the 12 rows of display pixels PX constituting the display panel 210 are grouped into three groups, and the light emission operation is executed simultaneously at different timings for each group. Therefore, the ratio (black insertion rate) of the black display period by the non-light emission operation in one frame period is approximately 33%. Here, in order to visually recognize a moving image clearly without flickering in human vision, it is generally a guideline that the black insertion rate is approximately 30% or more. Thus, a display device having a good display image quality can be realized.

Next, a third example of the drive control method in the display device according to the present invention will be described with reference to the drawings.
FIG. 20 is a timing chart schematically showing a third example of the display device drive control method according to the present invention. Here, the description of the drive control method equivalent to the above-described second example (see FIG. 18) is simplified.

A third example of the drive control operation of the display device 200 according to the present invention is as shown in FIG.
First, the display pixels PX arranged in the display panel 210 are grouped in advance for each of a plurality of rows that are not adjacent to each other, and switching for light emission driving of the display pixels PX in a specific row of a specific group is performed within one frame period. A threshold voltage detection operation (threshold voltage detection period Tdec) for detecting a threshold voltage of the element (thin film transistor);
For each group, after the threshold voltage is compensated for the display pixels PX in the row included in the group, a grayscale signal (grayscale current Idata, non-light-emitting display voltage Vzero) corresponding to the display data. Are sequentially executed, and a plurality of rows of display pixels PX (organic EL elements OEL) for each group are used as the display data (gradation signals) at a predetermined timing. By executing a display driving operation that simultaneously performs light emission operations with the corresponding luminance gradation, image information for one screen of the display panel 210 is displayed.

  Here, in the drive control operation according to the second example, specifically, first, all the display pixels PX arranged in the display panel 210 are configured, for example, as shown in FIG. Twelve rows of display pixels PX are divided into four rows of display pixels PX, such as the first, fourth, seventh, tenth rows, second, fifth, eighth, eleventh rows, third, sixth, ninth, and twelfth rows. Divide into 3 groups as a set.

  Then, in the first frame, the threshold voltage detection operation (threshold voltage detection period Tdec) for the display pixels PX in the first row in the group including the display pixels PX in the first, fourth, seventh, and tenth rows. After that, the display drive operation (precharge operation and write operation; Tth + Twrt) is executed for all the display pixels PX arranged in the display panel 210 in ascending order of the row number for each group.

  In the display driving operation for each row, the light emitting operation is performed for the group in which the writing operation to the display pixels PX of all the rows included in each group is completed. For example, in a group in which the display pixels PX in the first, fourth, seventh, and tenth rows are a set, the precharge operation and the write operation are executed in order from the display pixel PX in the first row. At the timing when the writing operation is finished for the display pixels PX, the display pixels PX for the four rows of the group simultaneously emit light based on the display data (gradation signal) written to each display pixel PX. This light emitting operation is performed at the timing at which the next precharge operation and writing operation are started with respect to the display pixel PX in the first row, or the threshold value for any of the 1, 4, 7, 10 rows. This is continued until the timing at which the voltage detection operation is started.

  In addition, at the timing when the writing operation is completed for the display pixel PX on the 10th row, in the group including the display pixels PX on the 2nd, 5th, 8th, and 11th rows, the display pixels PX on the 2nd row are sequentially arranged. At the timing when the precharge operation and the write operation are executed and the write operation is completed for the display pixels PX in the eleventh row, the display pixels PX for the four rows in the group simultaneously emit light. Thereafter, the same operation is repeatedly performed for the display pixels PX in each row of the next group.

  Next, in the second frame, the precharge operation and the write operation are sequentially performed in a group including the display pixels PX in the first, fourth, seventh, and tenth rows as a set, and the display pixels PX for the four rows in the group. At the timing of the simultaneous light emission operation, the display pixels PX in the second row (corresponding to the first row in the group) in the group including the display pixels PX in the second, fifth, eighth, and eleventh rows as a set. After the threshold voltage detection operation (threshold voltage detection period Tdec) is executed and the threshold voltage detection operation is completed, the precharge operation and the write operation are sequentially executed in the group.

  Next, the timing at which the precharge operation and the write operation are completed in the group including the display pixels PX in the second, fifth, eighth, and eleventh rows as a set, and the display pixels PX for the four rows in the group simultaneously emit light. Then, the precharge operation and the write operation are sequentially executed in a group including the display pixels PX in the third, sixth, ninth, and twelfth rows, and then the display pixels PX for the four rows in the group simultaneously emit light. Operate.

  Similarly, for each frame period, a threshold detection operation is performed for display pixels PX in a specific row included in the group for each preset group, and all rows included in each group are also included. At the time when the writing operation to the display pixel PX is completed, the display driving operation for causing all the display pixels PX in the group to emit light at once is repeatedly executed.

  As described above, the threshold voltage detection operation is sequentially performed on the display pixels PX in a specific row for each frame period, so that the display pixels PX in any row of the display panel 210 are performed in each frame period. The threshold voltage detection operation is executed, and the latest threshold voltage is always detected (monitored) with one frame period corresponding to the number of rows of the display panel as one cycle.

  Similarly to the display drive operation according to the second example, the threshold voltage detection operation, the precharge operation, and the write operation are performed on the display pixels PX in other rows of the same group. Is controlled so that all the display pixels in the group do not emit light and are set to a non-emission display state (black display state).

  In addition, such a display driving operation is similar to the above-described second example. For example, the threshold voltage detection operation, the precharge operation, and the write operation are performed on the display pixels PX in other rows of the same group. During the period in which the power supply driver 230 is executed, the supply voltage Vsc applied from the power supply driver 230 to the supply voltage line VL of each row in the group is kept at a low potential (Vs), and the display pixels PX in all rows of the same group After the threshold voltage detection operation, the precharge operation, and the write operation are completed, control is performed so that the high-potential supply voltage Vsc (= Ve) is applied to the supply voltage lines VL of all the rows included in the group. This can be realized. As in the second example (see FIG. 19) described above, the supply voltage line VL is applied so that the single supply voltage Vsc is applied to the display pixels PX in all rows included in each group. A configuration may be applied in which these are branched and arranged.

  Therefore, according to the drive control method (display drive operation) of such a display device, it is possible to obtain the same operation effect as the drive control method according to the first example described above, and the drive according to the second example. Similar to the control method, the display pixels PX of 12 rows constituting the display panel 210 are grouped into a plurality of groups, and the light emission operation is controlled at different timings for each group. A non-light emission operation (black display operation) is performed for a predetermined period during the frame period. In particular, in this drive control method as well, since the ratio of the black display period (black insertion rate) by the non-light emitting operation can be set to approximately 33%, the flickering of the moving image is suppressed and the sharpness is improved. A display device can be realized.

  In the drive control methods according to the second and third examples described above, the case where the display pixels PX constituting the display panel 210 are grouped into three groups has been described, but the present invention is limited to this. Needless to say, for example, the number of groups may be appropriately increased or decreased.

Below, the modification of the drive control method which concerns on the 2nd, 3rd example mentioned above is shown.
FIG. 21 is a timing chart schematically showing a modification (No. 1) of the second example of the drive control method for the display device according to the present invention, and FIG. 22 is a timing chart of the display device according to the present invention. 6 is a timing chart schematically showing a modification (No. 1) of the third example of the drive control method. FIG. 23 is a timing chart schematically showing a modification (No. 2) of the second example of the drive control method for the display device according to the present invention, and FIG. 24 is a display according to the present invention. 10 is a timing chart schematically showing a modification (No. 2) of the third example of the drive control method of the apparatus.

  In the modification (part 1) of the drive control method for the display device according to the second and third examples described above, for example, as shown in FIGS. 21 and 22, the display pixels PX constituting the display panel 210 are Divided into 4 groups (4 groups of 1st to 3rd lines, 4th to 6th lines, 7th to 9th lines, 10th to 12th lines in FIG. 21, 1st, 5th, 9th lines, 2 , 6, 10th row, 3rd, 7th, 11th row, 4th, 8th, 12th row), a threshold voltage detection operation is performed for display pixels PX in a specific row for each frame period. Then, after the precharge operation and the write operation are performed on the display pixels PX in each row at different timings for each group, control is performed so that the light emission operations are performed simultaneously. In this case, the ratio (black insertion rate) of the black display period due to the non-light emission operation in one frame period is approximately 25%, which is slightly lower than 30%, which is a guideline that the above-described flickering of moving images is not visually recognized. A display device having a good display image quality can be realized.

  Further, in the modification (No. 2) of the drive control method for the display device according to the second and third examples described above, for example, as shown in FIGS. 23 and 24, the display pixel PX constituting the display panel 210 is displayed. Are divided into two groups (in FIG. 23, 2 groups in the 1st to 6th rows and the 7th to 12th rows, in FIG. 24, 2 groups in the odd and even rows), and a specific period for each frame period. The threshold voltage detection operation is executed for the display pixels PX in the row, and the precharge operation and the writing operation are executed for the display pixels PX in each row at different timings for each group, and then the light emission operation is executed all at once. To control.

  In this case, the ratio (black insertion rate) of the black display period by the non-light emission operation in one frame period is approximately 50%, which is higher than 30%, which is a guideline for preventing the flicker of the moving image as described above, but the light emission operation. Since the period is only half of one frame period, the image information cannot be displayed with sufficient light emission luminance. Thus, by appropriately increasing the light emission luminance of each display pixel, the image information can be displayed with sufficient luminance and good display image quality.

Next, a fourth example of the drive control method in the display device according to the present invention will be described with reference to the drawings.
FIG. 25 is a timing chart schematically showing a fourth example of the drive control method for the display device according to the present invention. Here, the description of the drive control method equivalent to the above-described first to third examples (see FIGS. 17 to 24) is simplified. FIG. 26 is a main part configuration diagram showing an example of a display device for realizing a fourth example of the display device drive control method according to the present invention. Here, components equivalent to those of the display device described above will be described with the same reference numerals.

  As shown in FIG. 25, the fourth example of the drive control operation of the display device 200 according to the present invention is arranged in the display panel 210 first in the first half of one frame period (half of one frame period). After performing a threshold voltage detection operation (threshold voltage detection period Tdec) for detecting a threshold voltage with respect to a switching element (thin film transistor) for driving light emission of the display pixels PX in the specified row, the display panel 210 The precharge operation and the write operation are sequentially performed with respect to each row of display pixels PX arranged in a row, with the timing shifted for each row, and the latter half of one frame period (a half of one frame period) ), A display driving operation is performed in which the display pixels PX of all the rows arranged in the display panel 210 are caused to emit light at a luminance gradation according to display data at the same time. Image information 10 one screen is displayed.

  As described above, the threshold voltage detection operation is executed for the display pixels PX in a specific row for each frame period, and the drive control is performed so that all the display pixels PX are simultaneously lit in the second half of each frame period. Thus, in the first half of each frame period during which the threshold voltage detection operation, the precharge operation, and the write operation are performed, the light emission operation is not performed in any row of the display pixels PX, and all the display pixels PX Are controlled to perform a non-light emitting display operation (black display operation).

  Such a display driving operation is performed, for example, by supplying all the rows from the power supply driver 230 during a period in which the threshold voltage detection operation, the precharge operation, and the writing operation are performed on the display pixels PX of each row. After the supply voltage Vsc applied to the voltage line VL is kept at the low potential (Vs) state, the threshold voltage detection operation, the precharge operation, and the writing operation for the display pixels PX in all rows are completed, This can be realized by controlling so as to apply a high-potential supply voltage Vsc (= Ve) to the supply voltage line VL of the second row.

  Similar drive control is performed so that a single supply voltage Vsc is applied to all the display pixels PX at the same time. For example, as shown in FIG. 26, a single supply voltage line VL corresponds to all rows. A configuration in which all the display pixels PX arranged in the display panel 210 are shared and connected is applied, and a single supply voltage Vsc applied from the power supply driver 230 is applied to the display pixels PX in all rows. It can also be realized by being applied to.

  In this case, the configuration of the power supply driver 230 is such that a high-potential supply voltage Vsc (= Ve) and a low-potential supply voltage Vsc (= Vs) are determined at a predetermined timing based on, for example, a power supply control signal supplied from the system controller 250. Therefore, at least the shift register circuit as shown in FIG. 16 is not necessarily provided. Also in this drive control method, as in the case shown in FIG. 16, individual selection lines SL are provided for each row of the display panel 210, and individual selection signals Ssel are applied from the selection driver 220 at different timings. Is done.

  Therefore, according to such a display device drive control method (display drive operation), each frame period is divided into two parts, the first half and the second half, and the threshold voltage is detected for the display pixels in a specific row in the first half. After the operation is performed, the precharge operation and the write operation are sequentially performed on the display pixels in each row, and in the latter half, all the display pixels are controlled to perform the light emission operation at the same time. The ratio of the black display period by the light emission operation (black insertion rate) is approximately 50%, which exceeds 30%, which is the standard for not seeing the flicker of the moving image as described above, but the light emission operation period is only half of one frame period. Therefore, the image information cannot be displayed with sufficient light emission luminance, and the precharge period and the write operation period (particularly the write operation period) in each row are shortened. There is a possibility that sufficient time for writing the data (gradation signal) may not be secured. However, by appropriately increasing the light emission luminance of each display pixel and further increasing the current value of the gradation current, sufficient image information can be obtained. It is possible to display with high luminance and good display image quality.

PX display pixel DC light emission drive circuit SL selection line DL data line VL supply voltage line Tr11 to Tr13 thin film transistor Cs capacitor OEL organic EL element 100 display drive device 110 shift register / data register unit 120 display data latch unit 130 gradation signal generation unit 140 Detection voltage ADC
150 Compensation voltage DAC
160 threshold data latch unit 170 frame memory 180 data line input / output switching unit 200 display device 210 display panel 220 selection driver 230 power source driver 240 data driver 250 system controller 260 display signal generation circuit

Claims (17)

Near each intersection of a plurality of selection lines arranged in the row direction and a plurality of data lines arranged in the column direction, a current-controlled light emitting element and a light emitting driving element for supplying a light emission driving current to the light emitting element In a display device having a display panel provided with each of a plurality of display pixels comprising:
A selection driving unit configured to apply a selection signal to each of the selection lines of the display panel and set the display pixels of each row to a selected state in a selection period;
A data driver that generates a gradation signal corresponding to a luminance gradation of display data for displaying desired image information, and supplies the gradation signal to each display pixel of the row set in the selected state;
A power supply driver that applies, to the display pixels, either a first voltage that causes the display pixels to perform a light emission operation or a second voltage that performs a non-light emission operation as a supply voltage;
A drive control unit that operates each of the selection drive unit, the data drive unit, and the power supply drive unit at a predetermined timing;
With
The data driver includes a detection voltage application unit that applies a threshold detection voltage to the light emission drive element of each display pixel in the selected row via each data line. Then, after the threshold voltage detection voltage is applied to the light emitting drive element by the detection voltage application means, a part of the charge corresponding to the threshold voltage detection voltage is discharged and converged Threshold voltage detection means for detecting a subsequent voltage as a threshold voltage of the light emitting drive element via each data line, and based on the detected threshold voltage, the display pixel for each display pixel Compensation for creating a compensation voltage for compensating the threshold voltage, and applying the compensation voltage to each display pixel in the row set in the selected state prior to supply of the gradation signal to the display pixel Voltage application means,
The drive control unit individually supplies the gradation signal corresponding to the display data to all the display pixels arranged in the display panel by the selection driving unit and the data driving unit, and the display pixels Each display of the row set in the selected state by the power supply driving unit during an operation period in which the light emitting element provided in each of them is operated to emit light at a predetermined timing with a luminance gradation corresponding to the display data. Applying the second voltage as the supply voltage to the pixel for a period longer than the selection period and setting the display pixel in a non-light emitting display state, and setting the non-display period The display device is characterized in that the threshold voltage is detected by the threshold voltage detection means for at least one row of the display pixels of the display panel.   The display device according to claim 1, wherein the drive control unit causes the threshold voltage to be detected for each display pixel in a different row for each operation period.   The display device according to claim 2, wherein the drive control unit causes the threshold voltage to be detected for each display pixel in an adjacent row for each operation period. The light emission drive element provided in each of the display pixels includes a current path through which the light emission drive current flows to the light emitting element, and a control terminal for controlling a supply state of the light emission drive current,
The detection voltage application means applies the threshold detection voltage between the control terminal of the light emission drive element and one end of the current path,
The threshold voltage detection means detects, as the threshold voltage, a potential difference between the control terminal of the light emission drive element and one end side of the current path when no current flows in the current path. The display device according to any one of claims 1 to 3. The data driver has storage means for storing threshold data associated with the threshold voltage detected by the threshold voltage detection means for each display pixel,
The compensation voltage applying means generates the compensation voltage for causing the light emission driving element to hold a voltage component corresponding to the threshold voltage, based on the threshold data stored in the storage means, The display device according to claim 1, wherein the display device is individually applied to the light emission drive element of the display pixel.   The compensation voltage applying means holds the compensation voltage based on the threshold data stored in the storage means between the control terminal of the light emission drive element and one end side of the current path. The display device according to claim 5. The threshold voltage detection means includes means for converting the threshold voltage of the light emitting drive element detected as an analog signal into a digital signal and generating the threshold data,
The storage means stores the threshold data of a digital signal;
The compensation voltage applying means generates the compensation voltage composed of an analog signal for compensating the threshold voltage of the light emitting drive element based on the threshold data stored as a digital signal in the storage means. The display device according to claim 1, further comprising:   The data driver generates, as the gradation signal, a gradation current having a current value for causing the light emitting element to emit light at a luminance gradation corresponding to the display data, and through the data lines, The gradation current is individually supplied to each of the display pixels as the gradation signal, and a writing current corresponding to the gradation current is supplied to the current path of the light emitting drive element via each data line. The display device according to claim 1, further comprising a tone signal generation unit.   The gradation signal generating means includes means for generating a non-light emitting display voltage having a predetermined voltage value for causing the light emitting element to perform a non-light emitting operation when the luminance gradation of the display data is the lowest gradation. The display device according to claim 8, wherein the display device is a display device. The data driver is
Threshold value acquisition means for individually capturing and sequentially transferring the threshold data associated with the threshold voltage detected from each of the display pixels;
Data acquisition means for sequentially capturing and holding the display data for generating the gradation signals for each of the display pixels;
Further,
The storage means individually associates the threshold data associated with the threshold voltage for each of the plurality of display pixels transferred from the threshold acquisition means in association with each of the plurality of display pixels. Remember
The gradation signal generation unit generates the gradation signal corresponding to the display data for each of the plurality of display pixels held in the data acquisition unit, and the gradation signal is generated for each of the plurality of display pixels. 10. The display device according to claim 8, wherein a signal is supplied.   The data acquisition means and the threshold acquisition means share a configuration in which the display data is individually fetched individually and a configuration in which the threshold data is separately fetched and sequentially transferred. The display device according to claim 10.   The data driver includes at least a signal path for detecting the threshold voltage of the display pixel by the threshold voltage detection unit, a signal path for applying the compensation voltage to the display pixel by the compensation voltage application unit, And selectively connecting one of the signal paths for supplying the gradation signal to the display pixel by the gradation signal generating means and the single data line provided corresponding to the display pixel. 12. The display device according to claim 1, further comprising a signal path switching unit that performs switching control.   The data driver may be configured such that a signal path for applying the threshold detection voltage to the display pixel by the detection voltage applying unit is selectively connected to a single data line. The display device according to claim 12, wherein the display device is configured. The power supply unit divides the plurality of display pixels arranged in the display panel into a plurality of groups for each of a plurality of rows,
For each display pixel in each group, the drive control unit applies to each display pixel in the group during a period when any of the display pixels included in the group is set in the selected state. Commonly applying the second voltage to set each display pixel included in the group to a non-light emitting display state, and in a period when the display pixels of the group are not set to the selection period, The first voltage is commonly applied to the display pixels of a group, and the display pixels included in the group are set in a light emitting operation state. Display device. Each of the display pixels includes a light emission driving circuit that controls a light emission operation of the light emitting element,
The light emission driving circuit includes at least a first switch means in which the supply voltage is applied to one end of a current path and a connection contact with the light emitting element is connected to the other end of the current path, and a control terminal is the selection A second switch means connected to the line, the supply voltage being applied to one end of the current path, and the control terminal of the first switch means being connected to the other end of the current path, and the control terminal being the selection line A third switch means connected to the one end of the current path, the data line connected to one end of the current path, and the connection contact connected to the other end of the current path,
The light emission driving element is the first switch means;
The detection voltage applying means applies the threshold detection voltage between the control terminal of the first switch means and the connection contact,
The threshold voltage detecting means detects a potential between the control terminal of the first switch means and the connection contact as the threshold voltage;
The display device according to claim 1, wherein the compensation voltage application unit applies the compensation voltage between the control terminal of the first switch unit and the connection contact. .   16. The display device according to claim 15, wherein each of the first to third switch means is a field effect transistor having a semiconductor layer made of amorphous silicon.   The display device according to claim 1, wherein the light emitting element is an organic electroluminescence element.

Images