JP5120182B2 - Display device - Google Patents

Description

  The present invention relates to a display device having a touch panel function.

  In a display panel of an organic EL (Electro-Luminescence) display device, pixel circuits including organic EL elements which are self-luminous light emitting elements are arranged in a matrix. Since the organic EL display device is a self-luminous type, it can display an image with high contrast equivalent to that of a cathode ray tube.

  A display device in which a touch panel is stacked on a display panel of an organic EL display device is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-91342

When a touch panel for inputting a position is laminated on the display panel of the organic EL display device, light may be reflected from the touch panel, and thus the contrast of the displayed image is lowered.
Further, since it is necessary to provide a circuit for detecting a designated position on the touch panel separately from the display panel, the mounting area increases.

  The objective of this invention is providing the display apparatus provided with the touch panel function which can suppress the fall of the contrast of the displayed image and can reduce a mounting area.

Display device of the present invention includes a display panel, each comprising a plurality of display pixels arranged at intersections near the plurality of scan lines and a plurality of data lines arranged in a row direction and a column direction,
By selecting each display pixel connected to the scan line by supplying a scan signal to each scan line, and supplying a display signal to each data line during a selection period for selecting each display pixel A drive circuit for driving each of the selected display pixels;
With
Each display pixel supplies a light emitting element and a driving current corresponding to the display signal supplied to the light emitting element via each data line, and a physical parameter changes according to a pressure applied from the outside. A pixel driving circuit including a variable element that modulates a potential according to a display signal supplied to each data line according to a change in the physical parameter,
The drive circuit supplies the display signal to each data line and detects the potential of each data line at a measurement timing set within the selection period via each data line, and the variable element Determining whether or not the potential of each of the data lines is modulated, and determining a column corresponding to the data line that is determined to be modulated as a position where pressure is applied,
It is characterized by that.

Preferably, the drive circuit includes a gradation voltage generation circuit that generates a signal voltage having a voltage value corresponding to the display signal and outputs the signal voltage to each data line,
The determination circuit acquires the voltage value of each data line at the measurement timing, and compares the acquired voltage value with the voltage value of the data line when the potential is not modulated by the variable element. On the basis of the presence or absence of modulation of the potential,
It is characterized by that.

Preferably, the drive circuit includes a gradation current generation circuit that generates a signal current having a current value corresponding to the display signal and outputs the signal current to each data line,
The determination circuit acquires the voltage value of each data line at the measurement timing, and compares the acquired voltage value with the voltage value of the data line when the potential is not modulated by the variable element. On the basis of the presence or absence of modulation of the potential,
It is characterized by that.

Preferably, the variable element includes a capacitive element whose capacitance value changes as the physical parameter in accordance with an externally applied pressure,
The pixel driving circuit includes a capacitor that holds a voltage corresponding to the display signal,
In each of the display pixels, a circuit including the capacitor in the data line and the variable element are connected in parallel during the selection period.
It is characterized by that.

  Preferably, the capacitance value of the capacitive element increases in accordance with an increase in pressure applied from the outside.

Preferably, the variable element includes a resistance element whose electrical resistance value changes as the physical parameter in accordance with an externally applied pressure,
Each display pixel connects the resistance element of the variable element between the data line and a predetermined reference voltage in the selection period.
It is characterized by that.

Preferably, the electrical resistance value of the resistance element decreases in accordance with an increase in pressure applied from the outside.

Preferably, the display panel includes a plurality of power lines that are paired with the scanning lines and connected to the display pixels to which the corresponding scanning lines are connected,
The drive circuit includes a power driver that outputs the predetermined reference voltage to the power lines.
The picture element drive circuit,
The control terminal is connected to one electrode of the capacitor, one end of the conductive passage is connected to one electrode of the anode electrode and the variable element of the light emitting element and the other electrode of the capacitor, the other end of the current path A first transistor connected to the power supply line;
A control terminal is connected to the scanning line, one end of a current path is connected to the control terminal of the first transistor and one electrode of the capacitor, and the other end of the current path is connected to the power line and the first transistor. A second transistor connected to the other end of the current path;
A control terminal is connected to the scan line, one end of the current path is connected to the data line, and the other end of the current path is the other electrode of the capacitor, one electrode of the variable element, and the current of the first transistor. A third transistor connected to one end of the path and the anode electrode of the light emitting element;
Including
The predetermined reference voltage is applied to the other electrode of the variable element;
It is characterized by that.

Preferably, the display panel includes a plurality of power lines that are paired with the scanning lines and connected to the display pixels to which the corresponding scanning lines are connected,
The drive circuit includes a power driver that outputs the predetermined reference voltage to the power lines.
Each pixel driving circuit includes:
A control terminal is connected to one electrode of the capacitor and one electrode of the variable element, one end of the current path is connected to the other electrode of the capacitor and the anode electrode of the light emitting element, and the other end of the current path is A first transistor connected to the power line;
A control terminal is connected to the scan line, one end of a current path is connected to the data line, and the other end of the current path is one of the control terminal of the first transistor, one electrode of the capacitor, and one of the variable elements. A second transistor connected to the electrode;
Including
The predetermined reference voltage is applied to the other electrode of the variable element;
It is characterized by that.

Preferably, the driving circuit includes:
A scan driver connected to the plurality of scan lines and sequentially supplying the scan signals for sequentially selecting the display pixels to the scan lines;
When the determination circuit determines that the potential is modulated, the row position corresponding to the scan line from which the scan driver outputs the scan signal and the column position specified by the determination circuit A position detection circuit for identifying a position on the display panel to which pressure is applied,
It is characterized by having.

  ADVANTAGE OF THE INVENTION According to this invention, about the display apparatus with which the touchscreen function for inputting a position was added, the fall of the contrast of the displayed image can be suppressed and the mounting area for adding a touchscreen function can be reduced. it can.

<First Embodiment>
The organic EL display device 1a according to the first embodiment of the present invention will be described below. As shown in FIG. 1, the organic EL display device 1a includes a display panel 2a, a scanning driver 3, a power supply driver 4a, a data driver 5a, a system controller 6, and a display signal generation circuit 7. .

  The display panel 2a includes display pixels 21 arranged in a matrix, a plurality of scanning lines Ls1 to Lsn and power supply lines Lv1 to Lvn extending in a row direction (left and right direction in FIG. 1), and a column direction (up and down in FIG. 1). A plurality of data lines Ld1 to Ldm extending in the direction). The power supply lines Lv1 to Lvn are paired with the scanning lines Ls1 to Lsn, respectively, and are connected to the display pixels 21 to which the scanning lines Ls1 to Lsn are connected.

The display pixel 21 is disposed in the vicinity of the intersection of the scanning lines Ls1 to Lsn and the data lines Ld1 to Ldm.
FIG. 1 shows an example of displaying a monochrome image, for example. In the case of displaying a color image, a set of display pixels 21 that emit RGB colors are arranged in a matrix. For example, the display pixels 21 that emit light of each color of red (R), green (G), and blue (B) are set as a set, and the set is repeatedly arranged in the row direction and the same color in the column direction. A plurality of pixels are arranged.

  The scan driver 3 outputs a scan pulse for sequentially selecting the display pixels 21 arranged in the row direction based on the scan control signal supplied from the system controller 6. As shown in FIG. 2A, the scan driver 3 first applies a high level voltage Vhigh (for example, + 15V) higher than the reference voltage Vss (for example, ground potential GND = 0V) to the scan line Ls1 during the selection period ts. In other periods (light emission periods), a scan pulse that outputs a low level voltage Vlow (for example, −15 V) equal to or lower than the reference voltage Vss is output. The display pixel 21 connected to the scanning line Ls1 is selected during the selection period ts by this scanning pulse. Next, as shown in FIG. 2B, the scan driver 3 outputs a scan pulse having a high level voltage Vhigh to the scan line Ls2 in the next selection period ts. The display pixel 21 connected to the scan line Ls2 is selected during the next selection period ts by this scan pulse. Then, as shown in FIG. 2C, the scan driver 3 further outputs a scan pulse having a high level voltage Vhigh to the scan line Ls3 in the next selection period ts. The display pixel 21 connected to the scanning line Ls3 is further selected during the next selection period ts by this scanning pulse.

  Next, as shown in FIG. 2D, the scan driver 3 sequentially outputs a scan pulse that becomes a high-level voltage Vhigh during the selection period ts from the scan line Ls4 to the scan line Lsn, to the scan lines Ls4 to Lsn. The connected display pixels 21 are sequentially selected.

  Based on the power control signal supplied from the system controller 6, the power driver 4a, as shown in FIGS. 2E to 2H, scan lines Ls1 to Lsn that are paired with the power lines Lv1 to Lvn, respectively. While the scan pulse is being output, the reference voltage Vss (for example, ground potential GND = 0V) is output to the power supply lines Lv1 to Lvn, and the power supply voltage Vcc having a level higher than the reference voltage Vss is output during other periods. .

As shown in FIG. 3, the data driver 5a displays a shift register circuit 51, a data register circuit 52, a data latch circuit 53, a digital voltage / analog voltage conversion circuit (in order to display display data on the display panel 2a. DAVC) 54a.
The data driver 5a fetches display data (D1 to Dm) at a predetermined timing based on data control signals (shift clock signal CLK, sampling start signal STR, data latch signal STB) supplied from the system controller 6. The display signal (gradation voltage: -Vdata) corresponding to the display data (D1 to Dm) is generated at a predetermined timing, and is output to the data lines Ld1 to Ldm.

  As will be described later, the data driver 5a further includes, for example, a detection resistor 55 in order to detect a position where a human finger or a touch pen contacts the display panel 2a when the finger touches the display panel 2a. And an ADC (Analog-to-Digital Converter) 56a and a determination circuit 57a. The determination circuit 57a outputs a detection signal to the position detection circuit 61 included in the system controller 6 when detecting a position where a human finger or the like has contacted the display panel 2a.

The shift register circuit 51 includes a shift register (not shown), and supplies the shift signal to the data register circuit 52 while sequentially shifting the sampling start signal STR based on the shift clock signal CLK.
The data register circuit 52 sequentially captures the display data D1 to Dm at the timing of the shift signal supplied from the shift register circuit 51.
When the data latch signal STB is supplied from the system controller 7, the data latch circuit 53 latches and holds the display data D1 to Dm for one row captured in the data register circuit 52.
The DAVC 54a converts the display data D1 to Dm held in the data latch circuit 53 into an analog voltage display signal (negative gradation voltage: -Vd), and outputs it to the data lines Ld1 to Ldm.

  The display pixels 21 for one row selected by the scanning pulse read display signals output to the data lines Ld1 to Ldm to which the display pixels 21 are connected. The display signal read into the display pixel 21 is held until the display signal for the next screen is read and displayed as an image on the display panel 2a.

  As described above, the system controller 6 supplies the data control signal (shift clock signal CLK, shift start signal STR, latch signal STB) and display data D1 to Dm to the data driver 5a. Further, the system controller 6 supplies a scanning control signal and a power supply control signal to the scanning driver 3 and the power supply driver 4a, respectively. The system controller 6 supplies each control signal to operate each driver at a predetermined timing, causes each display pixel 21 to read the display signal, and causes the display panel 2a to display an image.

  Further, the system controller 6 includes a position detection circuit 61. As will be described later, for example, when a human finger or a touch pen touches the display panel 2a, the position detection circuit 61 detects a position where they touch the display panel 2a. In the position detection circuit 61, when a human finger or a touch pen touches the display panel 2a, the scanning lines Ls1 to Lsn from which the scanning driver 3 has output scanning pulses and the data driver 5a have output display signals. Based on the data lines Ld1 to Ldm, a position where a human finger, a touch pen, or the like contacts the display panel 2a is specified.

  For example, the display signal generation circuit 7 supplies display data extracted from an image signal supplied from the outside of the organic EL display device 1a to the data register circuit 52 of the data driver 5a. Here, when the image signal includes a timing signal component that defines the display timing of the image signal, such as a television broadcast signal (composite video signal), the display signal generation circuit 7 has a function of extracting display data. In addition, it may have a function of extracting a timing signal component and supplying a timing signal to the system controller 6. In this case, the system controller 6 receives the scanning control signal, the power supply control signal, and the data control signal supplied to the scanning driver 3, the power supply driver 4a, and the data driver 5a, respectively, based on the timing signal supplied from the display signal generation circuit 7. Generate.

  The organic EL display device 1a is an example of the display device of the present invention, the display panel 2a is an example of the display panel of the present invention, the display pixel 21 is an example of the display pixel of the present invention, and the scanning driver 3 The data driver 5a is an example of the drive circuit of the present invention, the data latch circuit 53 and the DAVC 54a are examples of the gradation voltage generation circuit of the present invention, and the position detection circuit 61 is an example of the position detection circuit of the present invention.

As shown in FIG. 4, the display pixel 21 has a pixel drive circuit 21D and an organic EL element OEL.
The pixel drive circuit 21D includes a first input transistor T21, a second input transistor T22, a light emission drive transistor T23, a capacitor Cs2, and a variable element Ev21.
The first input transistor T21, the second input transistor T22, and the light emission drive transistor T23 are n-channel TFTs (thin film transistors: thin film transistors) using amorphous silicon or polysilicon.
In the following, in the case of showing individual scanning lines, the subscripts 1 to n are appropriately omitted as in the case of the scanning line Ls. The same applies to the power supply line Lv and the data line Ld.

The first input transistor T21 has a gate connected to the scan line Ls, a source connected to the node N22, and a drain connected to the power supply line Lv and the drain of the light emission drive transistor T23.
The second input transistor T22 has a gate connected to the scan line Ls, a source connected to the data line Ld, and a drain connected to the node N21.
The light emission drive transistor T23 has a gate connected to the node N22, a source connected to the node N21, and a drain connected to the power supply line Lv and the drain of the first input transistor T21.

The capacitor Cs2 is connected between the node N22 and the node N21, that is, between the gate and the source of the light emission drive transistor T23.
In the variable element Ev21, one electrode is connected to the node N21, and the reference voltage Vss is applied to the other electrode. The variable element Ev21 is an element that functions as a variable capacitor that can change the capacitance value and also functions as a variable resistor that can change the resistance.

The organic EL element OEL includes an anode electrode, a cathode electrode, and an electron injection layer, a light emitting layer, a hole injection layer, and the like formed between these electrodes. The anode electrode of the organic EL element OEL is connected to the node N21, and the reference voltage Vss is applied to the cathode electrode.
When an electric current flows from the anode electrode to the cathode electrode, the organic EL element OEL is generated by recombination of holes supplied from the hole injection layer and electrons supplied from the electron injection layer in the light emitting layer. Emits light by energy.

As shown in FIG. 4, the data driver 5a includes a data latch circuit 53, a DAVC 54a, a detection resistor 55, an ADC 56a, and a determination circuit 57a. As described above, the data driver 5a includes the shift register circuit 51 and the data register circuit 52 shown in FIG. 3 as well as those shown in FIG.
FIG. 4 shows one data latch circuit 53, one DAVC 54a, one detection resistor 55, and one ADC 56a. In actuality, however, there are m pieces corresponding to each of the data lines Ld1 to Ldm. Is provided.
The resistance value of the detection resistor 55 may be relatively small, for example, about several Ω. The detection resistor 55 may be provided as a resistance element between a connection point between the DAVC 54a and the ADC 56a, or a wiring resistance of a wiring provided between the connection point between the DAVC 54a and the ADC 56a. It may consist of.

In the present embodiment, the display data is specified by voltage value data Vdata that is a digital signal. When the voltage value data Vdata is, for example, an 8-bit digital signal, the light emission gradation of the organic EL element OEL is 256 gradations.
When the voltage value data Vdata is supplied from the data latch circuit 53, the DAVC 54a converts it to a negative gradation voltage (−Vd) that is an analog voltage, and outputs it to the data line Ld via the detection resistor 55. The negative gradation voltage (−Vd) is reduced in magnitude by the detection resistor 55. That is, a voltage (−Vd ′) changed by the voltage drop caused by the detection resistor 55 is output to the data line Ld. When the voltage (−Vd ′) is output to the data line Ld, the current Id flows from the pixel drive circuit 21D to the DAVC 54a.

FIG. 5 is a diagram illustrating an example of the voltage or current of each part of the pixel drive circuit 21D. FIG. 5A and FIG. 5B show the voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 5C shows the voltage at the node N23, which is a connection point between the detection resistor 55 and the data line Ld. 5D shows the voltage Vgs between the gate and the source of the light emission drive transistor T23 (voltage between both electrodes of the capacitor Cs2), and FIG. 5E shows the current Ioel flowing through the organic EL element OEL. .
In the organic EL display device 1a of this embodiment, when a human finger, a touch pen, or the like is not in contact with the display panel 2a, the variable element Ev21 has a capacitance value that is small enough to be negligible and has a sufficient resistance. It is configured to be considered large and infinite. At this time, the scanning driver 3, the power supply driver 4a, and the data driver 5a operate as shown in FIG. 5, and an image is displayed on the display panel 2a.

First, in the selection period ts, the scan driver 3 outputs a scan pulse of a high level voltage Vhigh to the scan line Ls as shown in FIG. When a scan pulse is output to the scan line Ls, the source and drain of the first input transistor T21 and the second input transistor T22 are brought into conduction. At this time, the power supply driver 4a outputs the reference voltage Vss to the power supply line Lv as shown in FIG.
The DAVC 54a of the data driver 5a outputs a negative voltage (-Vd) corresponding to the voltage value data Vdata corresponding to the gradation value of the display data, and passes through the detection resistor 55 as shown in FIG. Then, a voltage (−Vd ′) is applied to the node N23. That is, the DAVC 54a sucks the current Id from the power supply driver 4a through the pixel drive circuit 21D of the display pixel 21.

As shown in FIG. 6A, the current Id flows from the power supply line Lv to the data line Ld through the drain and source of the light emission drive transistor T23 and between the drain and source of the second input transistor T22.
At this time, since the source and the drain of the first input transistor T21 are conductive, the potentials of the gate and the drain of the light emission drive transistor T23 are both the reference voltage Vss. Since the light emission drive transistor T23 is in a diode connection state, it operates in a saturation region.
Note that the voltage applied to the cathode electrode of the organic EL element OEL is the reference voltage Vss, and the voltage applied to the anode electrode is equal to the voltage of the node N21 and is equal to or lower than the reference voltage Vss. Therefore, no current flows through the organic EL element OEL.

  A capacitor Cs2 is connected between the gate and source of the light emission drive transistor T23. A reference voltage Vss is applied to one electrode of the capacitor Cs2 connected to the node N22. On the other hand, a current Id flows through the node N21, and as shown in FIG. 5D, the voltage between both electrodes of the capacitor Cs2 (between the gate and the source of the light emission driving transistor T23) is equal to the drain of the light emission driving transistor T23. The voltage Vgs1 is equal to the voltage between the gate and the source of the light emission drive transistor T23 when the current Id flows between the sources. As a result, the voltage of the node N23 (data line Ld) becomes substantially equal to Vss−Vgs1 in the selection period ts. On the other hand, as shown in FIG. 5C, since the voltage (−Vd ′) is applied to the node N23, Vgs1 and Vd ′ are substantially equal.

  Next, in the light emission period te, the light emission drive transistor T23 supplies the drive current Iem1 to the anode electrode of the organic EL element OEL.

  During the light emission period te, the scan driver 3 outputs a low-level voltage Vlow to the scan line Ls as shown in FIG. Therefore, the source and the drain of the first input transistor T21 and the source and the drain of the second input transistor T22 are not conductive. At this time, the power supply driver 4a outputs the power supply voltage Vcc to the power supply line Lv as shown in FIG. The power supply voltage Vcc is a voltage that allows the light emission drive transistor T23 to operate in the saturation region.

Since the source and the drain of the first input transistor T21 are non-conductive, the node N22 is in a floating state. The voltage Vgs1 applied during the selection period ts is held between both electrodes of the capacitor Cs2. On the other hand, as described above, a voltage capable of operating the light emission drive transistor T23 in the saturation region is applied to the drain of the light emission drive transistor T23.
For this reason, as shown in FIG. 6B, the light emission drive transistor T23 has a voltage between the gate and the source, that is, the voltage Vgs1 held between both electrodes of the capacitor Cs2, so that the organic EL element OEL A drive current Iem1 is supplied to the anode electrode. For this reason, the drive current Iem1 has the same current value as the current Id flowing through the node N21 during the selection period ts.

The ADC 56a converts the voltage applied to the node N23 (data line Ld) into a digital signal and supplies the digital signal to the determination circuit 57a.
The determination circuit 57a compares the voltage value data Vdata output from the data latch circuit 53 with the voltage of the node N23 (data line Ld) converted into a digital signal by the ADC 56a. The determination circuit 57a determines the potential of the data line Ld according to the display signal output to the data line Ld based on the magnitude of the difference extracted by comparing these voltages at the time immediately before the selection period ts ends. The presence or absence of modulation is determined.

  That is, the determination circuit 57a determines that the voltage value data Vdata and the voltage value of the node N23 (data line Ld) converted into a digital signal are substantially equal and the difference is within a predetermined range. Is determined not to be modulated, and it is determined that a human finger, a touch pen, or the like is not in contact with the display panel 2a. In other words, at this time, the determination circuit 57a determines that the capacitor Cs2 holds a voltage corresponding to the display signal.

  On the other hand, when the voltage value data Vdata and the voltage value of the node N23 (data line Ld) converted into a digital signal are different and the difference is larger than the predetermined range, the determination circuit 57a determines that the potential of the data line Ld is It is determined that it is modulated, and it is determined that a human finger, a touch pen, or the like is in contact with the display panel 2a. In other words, at this time, the determination circuit 57a determines that the capacitor Cs2 does not hold a voltage corresponding to the display signal.

  When the determination circuit 57a determines that the potential of the data line Ld is modulated, the determination circuit 57a outputs a determination result to the position detection circuit 61 assuming that a human finger, a touch pen, or the like is in contact with the display panel 2a.

Next, an example of a specific structure of the variable element Ev21 will be described. The variable element Ev21 has one electrode connected to the node N21. The source of the light emission drive transistor T23 is also connected to the node N21.
7 and 8 show examples of the structure of the display pixel 21 when one electrode of the variable element Ev21 and the source of the light emission drive transistor T23 are connected. FIG. 7 is an example of a plan view of the display pixel 21, and FIG. 8 is an example of a cross-sectional view between XI and XI shown in FIG. 7 and 8 are examples in the case where the display pixel 21 has a top emission structure.

  The anode electrode 121 is an anode electrode of the organic EL element OEL. The capacitor electrode Cs21 is an electrode connected to the node N22 of the capacitor Cs2. As shown in FIG. 7, the display pixel 21 has a source 21s, a gate 21g and a drain 21d of the first input transistor T21, and a source 22s and a gate 22g of the second input transistor T22 on the left side with the organic EL element OEL interposed therebetween. A drain 22d is disposed. Further, on the right side of the organic EL element OEL, the source 23s, the gate 23g, and the drain 23d of the light emission drive transistor T23 are arranged.

The source 21s of the first input transistor T21 is connected to the capacitor electrode Cs21 via the contact portion 143, and is further connected to the gate 23g of the light emission drive transistor T23 via the capacitor electrode Cs21.
The drain 22d of the second input transistor T22 is connected to the anode electrode 121, and the source electrode 22s is connected to the data line Ld via the contact portion 141. The gate 22g of the second input transistor T22 is connected to the scanning line Ls via the contact portion 142.
The drain 21d of the first input transistor T21 and the drain 23d of the light emission drive transistor T23 are connected to the power supply line Lv.
As will be described later, the source 23s of the light emission drive transistor T23 is connected to a variable element anode electrode 118 that forms one electrode of the variable element Ev21 via a contact portion 144.
Note that the contact portions 141 to 144 are used to vertically connect electrodes, wirings, and the like formed in different layers, and are formed by providing an opening in an insulating film or the like and filling this with a conductive material.

As shown in FIG. 8, the display pixel 21 is formed between the sealing substrate 111 and the pixel substrate 113. The sealing substrate 111 is made of, for example, a transparent resin material, and is configured to be deformed and bent to some extent when a human finger, a touch pen, or the like contacts the surface side of the sealing substrate 111 and pressure is applied.
On the pixel substrate 113, the gate 22g of the second input transistor T22 and the gate 23g of the light emission drive transistor T23 are formed. Further, one electrode Cs21 of the capacitor Cs2 and the data line Ld are formed on the pixel substrate 113, and an insulating film 114 is formed so as to cover them. The capacitor electrode Cs21 formed on the pixel substrate 113, the insulating film 114, and the anode electrode 121 function as the capacitor Cs2 included in the display pixel 21.

  The insulating film 114 is formed of an insulating material such as a silicon oxide film or a silicon nitride film, and is formed on the pixel substrate 113 so as to cover the data line Ld, the gate 22g, the gate 23g, and the capacitor electrode Cs21. The

  The first input transistor T21, the second input transistor T22, and the light emission drive transistor T23 are each an n-channel TFT. Each transistor is formed on the pixel substrate 113 as shown in FIG. The second input transistor T22 includes a semiconductor layer 221, a protective insulating film 222, a drain 22d, a source 22s, ohmic contact layers 224 and 225, and a gate 22g. The light emitting drive transistor T23 includes a semiconductor layer 231, a protective insulating film 232, a drain 23d, a source 23s, ohmic contact layers 234 and 235, and a gate 23g. In addition, although illustration is abbreviate | omitted, 1st input transistor T21 is formed similarly.

  In each of the transistors T21, T22, and T23, the gate is formed of, for example, aluminum-neodymium-titanium (AlNdTi) or chromium (Cr). The drain and the source are made of, for example, aluminum-titanium (AlTi) / Cr, AlNdTi / Cr, or Cr. In addition, an ohmic contact layer is formed between the drain and source and the semiconductor layer for low resistance contact.

  The anode electrode 121 has a two-layer structure of a light-reflective metal layer such as Al and a transparent conductive layer such as ITO (Indium Tin Oxide) laminated thereon. Each anode electrode 121 is insulated from the anode electrode 121 of another adjacent display pixel 21 by the interlayer insulating film 115.

The interlayer insulating film 115 is formed of an insulating material such as SiN or polyimide. The interlayer insulating film 115 is formed between the anode electrodes 121 and insulates the adjacent anode electrodes 121 from each other. The interlayer insulating film 115 is formed so as to cover the transistors T21, T22, and T23.
When the display pixel 21 is manufactured by the ink jet method, the interlayer insulating film 115 is formed with an opening 115a having a substantially square planar shape as shown in FIG. The light emitting area of the display pixel 21 is defined by the opening 115a. A partition wall 116 is further formed on the interlayer insulating film 115.

  The partition wall 116 is made of an insulating material such as polyimide, and is formed on the interlayer insulating film 115. The partition wall 116 prevents color mixing when the light emitting layer 124 formed on the anode electrode 121 is formed between adjacent pixels.

  The hole injection layer 122 is formed on the anode electrode 121 and has a function of supplying holes to the light emitting layer 124. The hole injection layer 122 is made of an organic polymer material that can inject and transport holes. As an organic compound-containing liquid containing an organic polymer hole injection / transport material, for example, polyethylenedioxythiophene (PEDOT) which is a conductive polymer and polystyrene sulfonic acid (PSS) which is a dopant are dispersed in an aqueous solvent. A PEDOT / PSS aqueous solution that is a dispersion is used.

  The interlayer 123 is formed on the hole injection layer 122. The interlayer 123 has a function of suppressing the hole injection property of the hole injection layer 122 to facilitate recombination of electrons and holes in the light emitting layer 124, in order to increase the light emission efficiency of the light emitting layer 124. Is provided.

  The light emitting layer 124 is formed on the interlayer 123. The light emitting layer 124 has a function of generating light by applying a predetermined voltage between the anode electrode 121 and the cathode electrode 125. The light emitting layer 124 is a known polymer light emitting material capable of emitting fluorescence or phosphorescence, for example, red (R) or green (G) containing a conjugated double bond polymer such as polyparaphenylene vinylene or polyfluorene. And a blue (B) light emitting material. In addition, these luminescent materials are appropriately coated with a solution (dispersion) dissolved (or dispersed) in an aqueous solvent or an organic solvent such as tetralin, tetramethylbenzene, mesitylene, and xylene by a nozzle coating method, an inkjet method, or the like. It is formed by volatilizing.

  The cathode electrode 125 has a two-layer structure made of a conductive material, for example, an electron injection layer made of a material having a low work function such as Ca or Ba, and a light-transmitting conductive layer such as ITO. The cathode electrode 125 is formed on the light emitting layer 124 and further formed so as to cover the partition wall 116. The cathode electrode 125 is connected to the reference voltage Vss.

The variable element anode electrode 118 is formed on the partition wall 116. The variable element anode electrode 118 is electrically insulated from the cathode electrode 125 by the insulating film 117.
The variable element anode electrode 118 is connected to the source 23s of the light emission drive transistor T23 through the contact portion 144. The contact portion 144 is formed by providing an opening in the partition wall 116 and the cathode electrode 125 and filling this with a conductive material.

  In addition, the variable element cathode electrode 112 forming the other electrode of the variable element Ev21 is disposed in contact with the sealing substrate 111. The variable element cathode electrode 112 is connected to the reference voltage Vss.

  When the display pixel 21 is manufactured by the ink jet method, the variable element anode electrode 118 is formed with an opening 115a matching the shape of the partition wall 116 as shown in FIG.

  On the variable element anode electrode 118, a plurality of insulating fine particles 131 and conductive fine particles 132 are arranged. The insulating fine particles 131 are true spherical fine particles having a diameter of several microns that do not conduct electricity. The insulating fine particles 131 are made of a material having a high dielectric constant and have flexibility, and are deformed when a pressure is applied. For example, it is manufactured using plastic as a material. By disposing the insulating fine particles 131 between the variable element anode electrode 118 and the variable element cathode electrode 112, the variable element anode electrode 118 and the variable element anode 118 can be changed when a human finger or a touch pen is not in contact with the display panel 2a. The spacing between the device cathode electrodes 112 can be kept uniform.

  The conductive fine particles 132 are true spherical fine particles that are conductive and smaller than the insulating fine particles 131. For example, it is manufactured by gold-plating the surface of fine particles made of plastic. When a human finger, a touch pen, or the like contacts the display panel 2a and pressure is applied to the sealing substrate 111, the insulating fine particles 131 are deformed and crushed, and the variable element anode electrode 118 and the variable element cathode electrode 112 are both conductive. Contact with the fine particles 132. At this time, the resistance between the variable element anode electrode 118 and the variable element cathode electrode 112 becomes extremely small.

  The variable element anode electrode 118 and the variable element cathode electrode 112 constitute a variable element Ev21. The variable element anode electrode 118 and the variable element cathode electrode 112 are normally insulated by an air layer. In this case, the resistance of the variable element Ev21 is several MΩ or more, and the capacitance value of the variable element Ev21 is negligibly small. In this case, as described above, the variable element Ev21 does not affect the light emission of the organic EL element OEL.

The capacitance value of the variable element Ev21 changes according to the distance between the variable element anode electrode 118 and the variable element cathode electrode 112. When a human finger, a touch pen, or the like comes into contact with the display panel 2a and pressure is applied to the display panel 2a from the surface side of the sealing substrate 111, the sealing substrate 111 is bent and dented, and the variable element anode electrode 118 and the variable element cathode The interval between the electrodes 112 is narrowed. As the distance between the variable element anode electrode 118 and the variable element cathode electrode 112 becomes narrower, the capacitance value of the variable element Ev21 increases.
When further pressure is applied to the display panel 2 a from the sealing substrate 111 side, both the variable element anode electrode 118 and the variable element cathode electrode 112 come into contact with the conductive fine particles 132. At this time, the capacitance value of the variable element Ev21 becomes extremely small, and at the same time, the resistance of the variable element Ev21 becomes extremely small.
Thus, the variable element Ev21 functions as a variable capacitor that can change the capacitance value, a variable resistor that can change the resistance, or both a variable capacitor and a variable resistor.
Here, applying pressure to the display panel 2a from the surface side of the sealing substrate 111 means applying pressure to the display panel 2a.

  7 to 9 show examples of the structure of the display pixel 21 when one electrode of the variable element Ev21 and the source of the light emission drive transistor T23 are connected, the one electrode of the variable element Ev21 and The drain of the second input transistor T22 may be connected.

  As described above, as pressure is applied to the display panel 2a and the distance between the variable element anode electrode 118 and the variable element cathode electrode 112 becomes narrower, the capacitance value of the variable element Ev21 increases and the variable element Ev21 serves as a capacitor. Start functioning.

Next, in the organic EL display device 1a of the present embodiment, an operation when a pressure is applied by a human finger or a touch pen contacting the display panel 2a will be described.
First, a case where the pressure applied to the display panel 2a is weak and the capacitance value of the variable element Ev21 is not so large will be described. FIG. 10 is a diagram illustrating an example of the voltage or current of each part of the display pixel 21 when the variable element Ev21 starts to function as a capacitor. 10A and 10B show the voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 10C shows the voltage at the node N23, which is a connection point between the detection resistor 55 and the data line Ld. FIG. 10D shows the output of the determination circuit 57a. FIG. 10E shows the voltage Vgs between the gate and the source of the light emission drive transistor T23 (that is, the voltage between both electrodes of the capacitor Cs2), and FIG. 10F shows the current Ioel flowing through the organic EL element OEL. Show. FIG. 11 shows an equivalent circuit related to the charging operation of the variable element Ev21 and the capacitor Cs2 when the variable element Ev21 functions as a capacitor.

In the selection period ts, the scan driver 3 outputs a scan pulse of the high level voltage Vhigh to the scan line Ls as shown in FIG. For this reason, the source and the drain of the first input transistor T21 are conducted. At this time, the power supply driver 4a outputs the reference voltage Vss to the power supply line Lv as shown in FIG. For this reason, the voltage of the node N22 becomes the reference voltage Vss. Here, the capacitor Cs2 is connected between the node N21 and the node N22.
On the other hand, in the variable element Ev21, one electrode is connected to the node N21, and the reference voltage Vss is applied to the other electrode. Therefore, the capacitor Cs2 and the variable element Ev21 form a parallel circuit connected in parallel between the node N23 and the reference voltage Vss, as shown in the equivalent circuit of FIG. 11, during the selection period ts. Therefore, when the capacitance value of the capacitor Cs2 is C1, and the capacitance value of the variable element Ev21 is C2, the capacitance value Ct1 of the capacitance provided between the node N23 and the reference voltage Vss is the sum of the capacitance value C1 and the capacitance value C2. Value.

  Therefore, when the data driver 5a outputs a negative gradation voltage (-Vd ') to the data line Ld, this voltage is also used for charging the capacitance value Ct1 including the variable element Ev21. At this time, as shown in FIG. 11, the detection resistor 55 and the capacitor having the capacitance value Ct1 are connected in series to form a so-called CR circuit. When the voltage (−Vd) output from the DAVC 54 a is applied to one end of the detection resistor 55, the voltage V (N 23) at the other end (node N 23) of the detection resistor 55 is the resistance of the detection resistor 55. When the value is R, the time from the start of application of the voltage (−Vd) is t, and the product of the resistance value R and the capacitance value Ct1 is a time constant τ.

That is, as shown in FIG. 10C, the change in the voltage V (N23) at the node N23 is delayed according to the time constant τ with respect to the application of the voltage (−Vd) from the DAVC 54a. It becomes. For this reason, the current value of the current Id2 drawn into the DAVC 54a of the data driver 5a via the drain and source of the light emission drive transistor T23 shown in FIG. 12A is immediately after the voltage (−Vd) is applied from the DAVC 54a. Then, it is smaller than the current Id in FIG. 6A and gradually increases. Accordingly, the rise in the voltage Vgs between the gate and the source of the light emission drive transistor T23 is delayed as shown in FIG. 10E, and becomes the voltage Vgs2 when the selection period ts ends.
However, the capacitance value of the variable element Ev21 is relatively small, and as shown in FIG. 10C, the voltage V (N23) of the node N23 is changed to the voltage (FIG. 5C) during the selection period ts. When Vss−Vd ′) is substantially reached, as shown in FIG. 10E, during the selection period ts, the voltage between both electrodes of the capacitor Cs2 (the voltage between the gate and the source of the light emission driving transistor T23). ) Vgs2 is substantially equal to the voltage Vgs1 when the current Id flows between the drain and source of the light emission drive transistor T23 in FIG. Further, as shown in FIGS. 10F and 12B, the current Iem2 supplied to the organic EL element OEL in the light emission period te has substantially the same current value as the current Iem1 in FIG.

  As illustrated in FIG. 10D, the determination circuit 57a acquires the voltage of the node N23 (data line Ld) converted into a digital signal at the voltage measurement timing tm immediately before the selection period ts ends, and the node N23 The voltage of (data line Ld) is compared with the voltage value data Vdata output from the data latch circuit 53. In this case, since the voltage of the node N23 at the voltage measurement timing tm is substantially equal to the voltage (−Vd) corresponding to the voltage value data Vdata, the determination circuit 57a determines that the potential of the data line Ld is not modulated, Outputs Low. In other words, the determination circuit 57a determines that the capacitor Cs2 holds the display signal.

Next, a case where pressure is further applied to the display panel 2a and the capacitance value of the variable element Ev21 further increases will be described.
FIG. 13 is a diagram illustrating an example of the voltage or current of each part of the pixel drive circuit 21D at this time. FIGS. 13A and 13B show the voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 13C shows the voltage at the node N23, which is a connection point between the detection resistor 55 and the data line Ld. FIG. 13D shows the output of the determination circuit 57a. FIG. 13E shows the voltage Vgs between the gate and source of the light emission drive transistor T23 (that is, the voltage of both electrodes of the capacitor Cs2), and FIG. 13F shows the current Ioel flowing through the organic EL element OEL. .

  The voltages of the scanning line Ls and the power supply line Lv shown in FIGS. 13A and 13B are the same as those shown in FIGS. 10A and 10B, respectively, and thus description thereof is omitted.

  As the capacitance value of the variable element Ev21 further increases, the time constant shown in the above equation (1) further increases. For this reason, as shown in FIG. 13C, the change in the voltage of the node N23 is further delayed than in the case of FIG. 10C, and when the selection period ts ends, the change in FIG. The voltage (Vss−Vd ′) is not reached. Therefore, the current value of the current Id3 drawn into the DAVC 54a of the data driver 5a via the drain and source of the light emission drive transistor T23 shown in FIG. 14A is further smaller than the current Id2 in FIG. . Accordingly, as shown in FIG. 13 (E), the voltage Vgs between the gate and the source of the light emission drive transistor T23 also rises more slowly than in the case of FIG. 10 (E), and when the selection period ts ends. The voltage becomes Vgs3. The voltage Vgs3 is smaller than Vgs2 in the case of FIG. Further, as shown in FIGS. 13E and 14B, the current Iem3 supplied to the organic EL element OEL in the light emission period te is smaller than the current Iem2 in FIGS. 10F and 12B. Has a current value.

  In this case, since the voltage of the node N23 at the voltage measurement timing tm is lower than the voltage (−Vd) corresponding to the voltage value data Vdata, the determination circuit 57a determines that the potential of the data line Ld is modulated, and High Is output. In other words, the determination circuit 57a determines that the capacitor Cs2 does not hold the display signal.

If the determination circuit 57a determines that the potential of the data line Ld is modulated, the position detection circuit 61 of the organic EL display device 1a determines that the potential of the data line Ld is modulated (1). ~ M).
When the position detection circuit 61 receives this number, it acquires the number (any one of 1 to n) of the scanning line from which the scanning driver 3 output the scanning pulse. The scanning line number is, for example, from the time when the scanning driver 3 outputs the first scanning pulse to the scanning line Ls1 until the determination circuit 57a determines that the potential of the data line Ld is modulated. It can be known by counting the number of pulses of the clock signal applied to. Alternatively, the scanning line number is the same as the scanning driver 3 after the scanning driver 3 outputs the first scanning pulse to the scanning line Ls1 and before the determination circuit 57a determines that the potential of the data line Ld is modulated. Can be obtained by counting the number of scan pulses sequentially output to the scan lines Ls2 to Lsn.

  The position detection circuit 61 identifies the acquired data line number and scanning line number as the position of the display panel 2a to which pressure is applied. However, for example, when a human finger or a touch pen touches the display panel 2a, a plurality of data line numbers and scanning line numbers may be specified at the same time. In this case, for example, the position detection circuit 61 specifies a plurality of positions on the display panel 2a specified by a plurality of data line numbers and scanning line numbers as a plurality of positions touched by a human finger or a touch pen. There may be. Alternatively, the position detection circuit 61 may be such that the center of the area specified by the number of data lines and the number of scanning lines is the position where a human finger or a touch pen touches the display panel 2a. In this way, the position where a human finger or a touch pen touches the display panel 2a can be determined based on the acquired data line number and scanning line number.

Next, the case where pressure is further applied to the display panel 2a and both the variable element anode electrode 118 and the variable element cathode electrode 112 are in contact with the conductive fine particles 132 will be described.
At this time, the resistance of the variable element Ev21 becomes extremely small, and the impedance of the circuit constituted by the capacitor Cs2 and the variable element Ev21 is lowered. For this reason, as shown in FIG. 15A, the current Id drawn into the DAVC 54a during the selection period ts flows mainly from the reference voltage Vss through the variable element Ev21. At this time, a certain amount of current flows also between the drain and the source of the light emitting drive transistor T23 in a diode connection state. Usually, a relatively high resistance of at least 1 KΩ or more is provided between the drain and the source of the light emitting drive transistor T23. Therefore, when the resistance value of the variable element Ev21 can be regarded as almost zero, the current flowing between the drain and source of the light emission drive transistor T23 with respect to the current flowing through the variable element Ev21 from the reference voltage Vss is almost equal to The current value is negligible. In this case, the voltage of the node N23 (data line Ld) approaches the reference voltage Vss. When the resistance value of the variable element Ev21 can be regarded as almost zero, the voltage at the node N23 (data line Ld) is substantially equal to the reference voltage Vss.

  FIG. 16 is a diagram illustrating an example of the voltage or current of each part of the pixel drive circuit 21D. FIGS. 16A and 16B show the voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 16C shows the voltage at the node N23, which is a connection point between the detection resistor 55 and the data line Ld. FIG. 16D shows the output of the determination circuit 57a. FIG. 16E shows the voltage Vgs between the gate and the source of the light emission drive transistor T23 (that is, the voltage between both electrodes of the capacitor Cs2), and FIG. 16F shows the current Ioel flowing through the organic EL element OEL. Show.

  The voltages of the scanning line Ls and the power supply line Lv shown in FIG. 16A and FIG. 16B are the same as those shown in FIG. 10A and FIG.

  As shown in FIG. 16E, the voltage Vgs4 between the gate and the source of the light emission driving transistor T23 becomes approximately 0 V in the selection period ts, and as shown in FIG. 16C, the voltage at the node N23 (data line Ld) is increased. The voltage is approximately equal to the reference voltage Vss. Further, as shown in FIGS. 15B and 16E, the current Iem4 supplied to the organic EL element OEL in the light emission period te becomes almost zero, and the organic EL element OEL does not emit light.

  In this case, the determination circuit 57a determines that the potential of the data line Ld is modulated, and outputs High. In other words, the determination circuit 57a determines that the capacitor Cs2 does not hold the display signal.

If the determination circuit 57a determines that the potential of the data line Ld is modulated, the position detection circuit 61 of the organic EL display device 1a determines that the potential of the data line Ld is modulated (1). ~ M). The position detection circuit 61 specifies the number of the received data line and the number of the scanning line from which the scanning driver 3 is outputting the scanning pulse at that time as the position of the display panel 2a to which pressure is applied. Based on the specified position, it is possible to know the position where a human finger or a touch pen touches the display panel 2a.
At this time, a plurality of data line numbers and scanning line numbers may be specified at the same time. In this case, for example, the position detection circuit 61 specifies a plurality of positions on the display panel 2a specified by a plurality of data line numbers and scanning line numbers as a plurality of positions touched by a human finger or a touch pen. There may be. Alternatively, the position detection circuit 61 may be configured such that the center of the area specified by the number of the plurality of data lines and the number of the power supply line is a position where a human finger or a touch pen touches the display panel 2a.

  The variable element Ev21 is an example of the variable element of the present invention, the pixel drive circuit 21D is an example of the pixel drive circuit of the present invention, and the determination circuit 57a is an example of the determination circuit of the present invention.

<Second Embodiment>
Next, an organic EL display device 1b according to a second embodiment of the present invention will be described. As shown in FIG. 17, the organic EL display device 1b includes a display panel 2b, a scan driver 3, a power supply driver 4b, a data driver 5b, a system controller 6, and a display signal generation circuit 7. .
The display panel 2b includes display pixels 22 as shown in FIG. The pixel drive circuit 22D included in the display pixel 22 is different from the pixel drive circuit 21D of the first embodiment in that the pixel drive circuit 22D includes two transistors. Therefore, the power driver 4b and the data driver 5b are also different from the power driver 4a and the data driver 5a in FIG. The same components in FIGS. 1 and 17 are denoted by the same reference numerals.

As shown in FIG. 18, the display pixel 22 has a pixel drive circuit 22D and an organic EL element OEL.
The pixel drive circuit 22D includes an input transistor T31, a light emission drive transistor T32, a capacitor Cs3, and a variable element Ev31.
The input transistor T31 and the light emission drive transistor T32 are n-channel TFTs using amorphous silicon or polysilicon.

The input transistor T31 has a gate connected to the scan line Ls, a source connected to the node N31, and a drain connected to the data line Ld.
The light emission drive transistor T32 has a gate connected to the node N31, a source connected to the node N32, and a drain connected to the power supply line Lv.

The capacitor Cs3 is connected between the node N31 and the node N32, that is, between the gate and the source of the light emission drive transistor T32.
In the variable element Ev31, one electrode is connected to the node N31, and the reference voltage Vss is applied to the other electrode. The variable element Ev31 is a variable capacitor that can change a capacitance value, a variable resistor that can change a resistance, or a variable element that functions as both a variable capacitor and a variable resistor, similarly to the EV 21 of the first embodiment. It is.
The anode electrode of the organic EL element OEL is connected to the node N32, and the reference voltage Vss is applied to the cathode electrode.

As shown in FIG. 18, the data driver 5b includes a data latch circuit 53, a digital voltage / analog current conversion circuit (DAVC) 54b, a detection resistor 55, an ADC 56b, and a determination circuit 57a. In addition, the data driver 5b includes a shift register circuit 51 and a data register circuit 52 which are not shown in FIG.
The data driver 5b in FIG. 18 differs from the data driver 5a in FIG. 4 in that it outputs a positive gradation voltage Vd. The same components in the data driver 5a in FIG. 4 and the data driver 5b in FIG. 18 are denoted by the same reference numerals.

The display data is specified by voltage value data Vdata which is a digital signal, as in the first embodiment. When the voltage value data Vdata is, for example, an 8-bit digital signal, the light emission gradation of the organic EL element OEL is 256 gradations.
In the first embodiment, the DAVC 54 a converts the voltage value data Vdata supplied from the data latch circuit 53 into a negative gradation voltage (−Vd) that is an analog voltage, whereas in the present embodiment, the DAC 54 b The value data Vdata is converted into a positive gradation voltage Vd.
The positive gradation voltage Vd is applied to the node N33 (data line Ld) via the detection resistor 55.

The ADC 56b converts the voltage applied to the node N33 (data line Ld) into a digital signal and supplies the digital signal to the determination circuit 57a.
The determination circuit 57a acquires the voltage of the node N33 (data line Ld) converted into a digital signal by the ADC 56b at the measurement timing tm immediately before the selection period ts ends, and acquires the acquired node N33 (data line Ld) and data The voltages of the voltage value data Vdata output from the latch circuit 53 are compared. The determination circuit 57a determines whether or not the potential of the data line Ld is modulated based on the magnitude of the difference extracted by comparing these voltages at a time immediately before the selection period ts ends. The determination method in the determination circuit 57a is the same as that in the first embodiment.

In the organic EL display device 1b of this embodiment, the scanning driver 3 and the power supply driver 4b operate as shown in FIG.
The operation of the scan driver 3 is the same as that in the first embodiment. That is, as shown in FIGS. 19A to 19D, the scan driver 3 is at a high level during the selection period ts from the scan line Ls1 to the scan line Lsn based on the scan control signal supplied from the system controller 6. Are sequentially output to select the display pixels 22 connected to the scan lines Ls1 to Lsn.

The power supply lines Lv1 to Lvn are connected to a common node N11 as shown in FIG.
Unlike the power supply driver 4a of the first embodiment, the power supply driver 4b always applies a power supply voltage Vcc higher than the reference voltage Vss to the power supply lines Lv1 to Lvn through the node N11 as shown in FIG. 19 (E). Output.

  FIG. 20 is a diagram illustrating an example of the voltage or current of each part of the pixel drive circuit 22D. 20A and 20B show the voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 20C shows the voltage of the node N33, which is a connection point between the detection resistor 55 and the data line Ld. FIG. 20D shows the output of the determination circuit 57a. 20E shows the voltage Vgs between the gate and the source of the light emission drive transistor T32 (that is, the voltage between both electrodes of the capacitor Cs3), and FIG. 20F shows the current Ioel flowing through the organic EL element OEL. Show.

  In the organic EL display device 1b of the present embodiment, when a human finger, a touch pen, or the like is not in contact with the display panel 2b, the capacitance value of the variable element Ev31 is small enough to be ignored and the resistance is sufficiently large and infinite. Can be considered large. In this case, the scanning driver 3, the power supply driver 4b, and the data driver 5b operate as shown in FIG. 20, and an image is displayed on the display panel 2b.

First, in the selection period ts, a voltage corresponding to the gradation value of the voltage value data Vdata is written to the display pixel 22.
In the selection period ts, as shown in FIG. 20A, the scan driver 3 outputs a scan pulse of a high-level voltage Vhigh higher than the reference voltage Vss to the scan line Ls. When a scan pulse is output to the scan line Ls, the source and drain of the input transistor T31 are conducted. As shown in FIG. 20B, the power supply driver 4b constantly outputs a power supply voltage Vcc higher than the reference voltage Vss to the power supply line Lv.

The DAVC 54b outputs a gradation voltage Vd corresponding to the gradation value of the voltage value data Vdata. The gradation voltage Vd is applied to the node N33 (data line Ld) via the detection resistor 55.
The voltage applied to the node N33 (data line Ld) passes between the drain and source of the input transistor T31 and is applied to the gate of the light emission drive transistor T32. Since almost no current flows through the data line Ld, the voltage of the node N33 (data line Ld) becomes substantially equal to the gradation voltage Vd as shown in FIG.
A capacitor Cs3 is connected between the gate and source of the light emission drive transistor T32. A voltage Vgs5 applied between the gate and the source of the light emission driving transistor T32 (a voltage applied between both electrodes of the capacitor Cs3) Vgs5, when the voltage between the anode electrode and the cathode electrode of the organic EL element OEL is Voel, As shown in FIGS. 20E and 21A, the voltage Vd−Voel.

  At this time, since the voltage applied to the cathode electrode of the organic EL element OEL is the reference voltage Vss, as shown in FIGS. 20 (F) and 21 (A), the light emission drive transistor T32 includes both the capacitor Cs3. A drive current Iem5 corresponding to the voltage Vd−Voel held between the two electrodes is supplied to the anode electrode of the organic EL element OEL. The organic EL element OEL emits light with a luminance corresponding to the current value of the drive current Iem5.

  Next, in the light emission period te, the scan driver 3 outputs a low-level voltage Vlow equal to or lower than the reference voltage Vss to the scan line Ls, as shown in FIG. For this reason, the source and drain of the input transistor T31 become non-conductive.

Since the source and drain of the input transistor T31 are not conductive, the node N31 is in a floating state. As shown in FIGS. 20E and 21B, the voltage Vgs5 (Vd−Voel) written in the selection period is held between both electrodes of the capacitor Cs3.
Accordingly, as shown in FIGS. 20F and 21B, the light emission drive transistor T32 has a drive current Iem5 corresponding to the voltage Vgs5 (Vd−Voel) held between both electrodes of the capacitor Cs3. Is continuously supplied to the anode electrode of the organic EL element OEL, and the organic EL element OEL continuously emits light according to the drive current Iem5.

As shown in FIG. 20D, the determination circuit 57a compares the voltage value data Vdata and the voltage of the node N33 (data line Ld) at the voltage measurement timing tm immediately before the selection period ts ends, and calculates the difference due to the comparison. Based on the magnitude, the presence / absence of modulation of the potential of the data line Ld according to the display signal output to the data line Ld is determined.
In this case, in the determination circuit 57a, since the voltage value data Vdata and the voltage of the node N33 (data line Ld) are substantially equal and the difference is relatively small and within a predetermined range, the potential of the data line Ld is modulated. Judge that there is no. In other words, the determination circuit 57a determines that the capacitor Cs3 holds the display signal.

Next, in this embodiment, an operation when pressure is applied to the display panel 2b with a human finger, a touch pen, or the like will be described.
As pressure is applied to the display panel 2b and the distance between the variable element anode electrode 118 and the variable element cathode electrode 112 becomes narrower, the variable element Ev31 increases its capacitance value and starts to function as a capacitor.

  First, a case where the pressure applied to the display panel 2b is weak and the capacitance value of the variable element Ev31 is not so large will be described. FIG. 22 is a diagram illustrating an example of the voltage or current of each part of the pixel drive circuit 22D when the variable element Ev31 starts to function as a capacitor. 22A and 22B show the voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 22C shows the voltage at the node N33, which is a connection point between the detection resistor 55 and the data line Ld. FIG. 22D shows the output of the determination circuit 57a. 22E shows the voltage Vgs between the gate and the source of the light emission drive transistor T32 (that is, the voltage between both electrodes of the capacitor Cs3), and FIG. 22F shows the current Ioel flowing through the organic EL element OEL. Show. FIG. 23 shows an equivalent circuit related to the charging operation of the capacitive components of the variable element Ev31, the capacitor Cs3, and the organic EL element OEL when the variable element Ev31 functions as a capacitor.

  The voltages of the scanning line Ls and the power supply line Lv shown in FIGS. 22A and 22B are the same as those shown in FIGS. 20A and 20B, respectively, and thus description thereof is omitted.

The DAVC 54b outputs the gradation voltage Vd corresponding to the gradation value of the voltage value data Vdata during the selection period ts. The gradation voltage Vd is applied to the node N33 (data line Ld) via the detection resistor 55.
At this time, as shown in the equivalent circuit of FIG. 23, the circuit in which the capacitor Cs3 and the organic EL element OEL are connected in series and the variable element Ev31 are in parallel between the node N33 (data line Ld) and the reference voltage Vss. A parallel circuit connected to is configured. Therefore, when the capacitance value of the capacitance in which the capacitor Cs3 and the capacitance component of the organic EL element OEL are connected in series is C3, and the capacitance value of the variable element Ev31 is C4, the capacitance provided between the node N33 and the reference voltage Vss. The capacitance value Ct2 is a sum of the capacitance value C3 and the capacitance value C4.

  Therefore, when the data driver 5b outputs the gradation voltage Vd to the data line Ld, this voltage is also used for charging the capacitance value Ct2 including the variable element Ev31. At this time, as shown in FIG. 23, the detection resistor 55 and the capacitor having the capacitance value Ct2 are connected in series. When the voltage (Vd) output from the DAVC 54 b is applied to one end of the detection resistor 55, the voltage V (N 33) at the other end (node N 33) of the detection resistor 55 is the resistance value of the detection resistor 55. Is represented by the following equation (2), where t is the time from the start of application of the voltage (Vd), and t is the product of the resistance value R and the capacitance value Ct2.

That is, as shown in FIG. 22C, the change in the voltage V (N33) at the node N33 is delayed according to the magnitude of the time constant τ with respect to the application of the voltage (Vd) from the DAVC 54b. Become. As a result, as shown in FIG. 20E, the rise in the voltage Vgs between the gate and the source of the light emission drive transistor T32 is also delayed.
However, when the capacitance value of the variable element Ev31 is relatively small and the voltage of the node N33 (data line Ld) almost reaches the gradation voltage Vd during the selection period ts as shown in FIG. The voltage Vgs6 between the gate and the source of the light emission drive transistor T32 at the end of the selection period ts is substantially equal to the voltage Vgs5 in FIG. 20E, as shown in FIG. For this reason, as shown in FIG. 22F, the organic EL element OEL emits light with substantially the same luminance as that in FIG. 20F during the light emission period te.

  For this reason, as shown in FIG. 22 (F), during the light emission period te, the light emission drive transistor T32 supplies the drive current Iem6 corresponding to the voltage Vd−Voel held between both electrodes of the capacitor Cs3 to the organic EL element. Supply to the anode electrode of the OEL. The organic EL element OEL emits light with a luminance corresponding to the current value of the drive current Iem6. Since the drive current Iem6 is substantially equal to the drive current Iem5 shown in FIG. 20F, the organic EL element OEL emits light with substantially the same luminance as in FIG. 20F during the light emission period te.

  In this case, since the voltage of the node N33 (data line Ld) is substantially equal to the gradation voltage Vd at the voltage measurement timing tm immediately before the selection period ts ends, the determination circuit 57a does not modulate the potential of the data line Ld. And Low is output. In other words, the determination circuit 57a determines that the capacitor Cs3 holds the display signal.

Next, a case where pressure is further applied to the display panel 2b and the capacitance value of the variable element Ev31 further increases will be described.
FIG. 24 is a diagram illustrating an example of the voltage or current of each part of the pixel drive circuit 22D in this case. FIG. 24A and FIG. 24B show voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 24C shows the voltage at the node N33, which is a connection point between the detection resistor 55 and the data line Ld. FIG. 24D shows the output of the determination circuit 57a. FIG. 24E shows the voltage Vgs between the gate and the source of the light emission drive transistor T32 (that is, the voltage between both electrodes of the capacitor Cs3), and FIG. 24F shows the current Ioel flowing through the organic EL element OEL. Show.

  The voltages of the scanning line Ls and the power supply line Lv shown in FIGS. 24A and 24B are the same as those shown in FIGS. 20A and 20B, respectively, and thus description thereof is omitted.

  As shown in FIG. 24C, when the capacitance value of the variable element Ev31 is further increased, the time constant expressed by the above equation (2) is further increased. For this reason, the change in the voltage of the node N33 (data line Ld) is further delayed than in the case of FIG. 22C, and the voltage of the node N33 (data line Ld) is reduced until the selection period ts ends. The regulated voltage Vd is not reached. Accordingly, as shown in FIG. 24E, the voltage Vgs7 between the gate and the source of the light emission driving transistor T32 is further delayed from the case of FIG. 22E, and light emission in the light emission period te is performed. The voltage Vgs7 between the gate and source of the drive transistor T32 is lower than the voltage Vgs6 shown in FIG. Therefore, the drive current Iem7 supplied to the anode electrode of the organic EL element OEL during the light emission period te is smaller than Iem6 in the case of FIG. 22F as shown in FIG. 24F, and the organic EL element OEL Emits light with a lower luminance than in the case of FIG.

  In this case, at the voltage measurement timing tm immediately before the selection period ts ends, the voltage of the node N33 (data line Ld) is lower than the gradation voltage Vd. For this reason, the determination circuit 57a determines that the potential of the data line Ld is modulated, and outputs High as shown in FIG. In other words, the determination circuit 57a determines that the capacitor Cs3 does not hold the display signal.

When the determination circuit 57a determines that the potential of the data line Ld is modulated, the position detection circuit 61 of the organic EL display device 1b notifies the position of the data line (1 to m) of the data line determined to be modulated. Send one).
The position detection circuit 61 specifies the number of the received data line and the number of the scanning line from which the scanning driver 3 is outputting the scanning pulse at that time as the position of the display panel 2b to which pressure is applied. Based on the specified position, it is possible to know a position where a human finger or a touch pen touches the display panel 2b.

Next, a case where pressure is further applied to the display panel 2 b and both the variable element anode electrode 118 and the variable element cathode electrode 112 are in contact with the conductive fine particles 132 will be described.
In this case, the capacitance value of the variable element Ev31 becomes extremely small, and at the same time, the resistance of the variable element Ev31 becomes extremely small. At this time, as shown in FIG. 25A, the current flowing through the data line Ld by the gradation voltage Vd output from the DAVC 54b mainly flows from the data driver 5b through the variable element Ev31 to the reference voltage Vss.

  FIG. 26 is a diagram illustrating an example of the voltage or current of each part of the pixel drive circuit 22D in this case. FIG. 26A and FIG. 26B show the voltages of the scanning line Ls and the power supply line Lv, respectively. FIG. 26C shows the voltage at the node N33, which is a connection point between the detection resistor 55 and the data line Ld. FIG. 26D shows the output of the determination circuit 57a. FIG. 26E shows the voltage Vgs between the gate and the source of the light emission drive transistor T32 (that is, the voltage between both electrodes of the capacitor Cs3), and FIG. 26F shows the current Ioel flowing through the organic EL element OEL. Show.

  The voltages of the scanning line Ls and the power supply line Lv shown in FIG. 26A and FIG. 26B are the same as those shown in FIG. 20A and FIG.

  Since the resistance of the variable element Ev31 is extremely small, the voltage of the node N33 (data line Ld) is substantially equal to the reference voltage Vss as shown in FIG. Further, as shown in FIG. 26E, the voltage Vgs8 between the gate and the source of the light emission drive transistor T23 is approximately 0V.

  Further, since the voltage at the node N31 is substantially equal to the reference voltage Vss, the source and drain of the light emission drive transistor T32 are non-conductive, and the drive current Iem8 supplied to the anode electrode of the organic EL element OEL during the light emission period te is: As shown in FIG. 25B and FIG. 26F, the current is almost 0A. For this reason, the organic EL element OEL does not emit light during the light emission period te.

  In this case, since the voltage of the node N33 (data line Ld) is substantially the reference voltage Vss at the voltage measurement timing tm immediately before the selection period ts ends, the determination circuit 57a has the potential of the data line Ld modulated. And High is output as shown in FIG. In other words, the determination circuit 57a determines that the capacitor Cs3 does not hold the display signal.

  When the determination circuit 57a determines that the potential of the data line Ld is modulated, the position detection circuit 61 of the organic EL display device 1b determines that the potential of the data line Ld is modulated (1). ~ M). The position detection circuit 61 specifies the number of the received data line and the number of the scanning line from which the scanning driver 3b is outputting the scanning pulse at that time as the position of the display panel 2b to which pressure is applied. Based on the specified position, it is possible to know a position where a human finger or a touch pen touches the display panel 2b.

  The organic EL display device 1b is an example of the display device of the present invention, the display panel 2b is an example of the display panel of the present invention, the display pixel 22 is an example of the display pixel of the present invention, and the scanning driver 3 The data driver 5b is an example of a drive circuit according to the present invention, the data latch circuit 53 and the DAVC 54b are examples of a gradation voltage generation circuit according to the present invention, and the variable element Ev31 is an example of a variable element according to the present invention. The circuit 22D is an example of the pixel driving circuit of the present invention.

<Third Embodiment>
Next, an organic EL display device 1c according to a third embodiment of the present invention will be described. As shown in FIG. 27, the organic EL display device 1c includes a display panel 2a, a scan driver 3, a power supply driver 4a, a data driver 5c, a system controller 6, and a display signal generation circuit 7. .
The organic EL display device 1c is different from the organic EL display device 1a shown in FIG. 1 in that the system controller 6 designates a display signal corresponding to display data by a current value. Due to this difference, the configuration of the data driver 5c is different from the data driver 5a included in the organic EL display device 1a. Except for this point, the organic EL display device 1c has the same configuration as the organic EL display device 1a. The same components in FIGS. 1 and 27 are denoted by the same reference numerals.

As shown in FIG. 28, the data driver 5c includes a shift register circuit 51, a data register circuit 52, a data latch circuit 53, and a digital current / analog current conversion circuit (DAIC) 54c. As shown in FIG. 29, the data driver 5c further includes an ADC 56a and a determination circuit 57b.
The configuration of the shift register circuit 51, the data register circuit 52, the data latch circuit 53, and the ADC 56a in the data driver 5c is the same as that of the data driver 5a.
Hereinafter, differences between the data driver 5c and the data driver 5a will be described.

The system controller 6 designates the light emission gradation of the organic EL element OEL by the current value data Idata which is a digital signal. When the current value data Idata is, for example, an 8-bit digital signal, the light emission gradation is 256 gradations.
For example, the DAIC 54c generates a negative gradation current (-Id) corresponding to the current value data Idata using a multi-stage mirror circuit based on the reference current and outputs the negative gradation current (-Id) to the data line Ld. That is, the DAIC 54c sucks the current Id from the data line Ld to which the DAIC 54c is connected. The organic EL element OEL emits light based on a voltage corresponding to the current value of the current Id.

When a human finger, a touch pen, or the like is not in contact with the display panel 2a, the variable element Ev21 is small enough to ignore the capacitance value, and the resistance is sufficiently large and infinite, as in the first embodiment. Can be considered large. In this case, a negative gradation voltage (−Vd ′) corresponding to the negative gradation current −Id is generated at the node 23 (data line Ld).
When a finger or a touch pen touches the display panel 2a and the capacitance value of the variable element Ev21 increases, a part of the gradation current (−Id) output from the DAIC 54c to the data line Ld is charged to the variable element Ev21. Therefore, the current flowing between the drain and the source of the light emission driving transistor T23 is smaller than the gray-scale current (−Id). As a result, as in the first embodiment, the potential of the data line Ld is modulated according to the pressure applied to the display panel 2a.
Therefore, the determination circuit 57b according to the present embodiment checks the voltage of the node N23 (data line Ld) by the same method as the determination circuit 57a according to the first embodiment, so that a human finger, a touch pen, or the like is displayed on the display panel. It is determined whether or not it is in contact with 2a, and when a human finger or a touch pen is in contact with the display panel 2a, the position can be specified.

Specifically, for example, when the organic EL display device 1c is shipped, the correspondence between the voltage generated at the node N23 (data line Ld) is measured for the current value data Idata corresponding to all 256 gradations. The correspondence relationship is stored in a table (memory) (not shown).
When the image is displayed on the display panel 2a, the determination circuit 57b converts the current value data Idata output from the data latch circuit 53 into voltage value data. Then, the determination circuit 57b refers to the table in which the correspondence between the current value data Idata and the voltage generated at the node N23 (data line Ld) is stored, and determines the current value data Idata output from the data latch circuit 53 as the voltage value. Convert to data. The determination circuit 57b compares the voltage value data with the voltage of the node N23b (data line Ld) converted into a digital signal by the ADC 56a. The determination circuit 57b determines the potential of the data line Ld according to the display signal output to the data line Ld on the basis of the magnitude of the difference extracted by comparing these voltages immediately before the selection period ts ends. The presence or absence of modulation is determined.

The threshold voltage Vth of the light emitting drive transistor T23 may increase depending on the drive history. In particular, when an amorphous silicon TFT is used as the transistor, the variation of the threshold voltage Vth is relatively large.
For this reason, even if the gradation of light emission of the organic EL element OEL is designated by the same current value data Idata, the voltage generated at the node N23 (data line Ld) increases as the operating time of the organic EL display device 1c increases. .
However, even when the threshold voltage Vth of the light emitting drive transistor T23 increases, if the pressure applied to the display panel 2a is large, the determination circuit 57b determines that a human finger or a touch pen has touched the display panel 2a. Judgment can be made. For this reason, the change in the threshold voltage Vth of the light emission drive transistor T23 does not greatly affect the determination by the determination circuit 57b as to whether or not a human finger, a touch pen, or the like is in contact with the display panel 2a.

  Further, for example, each time the power of the organic EL display device 1c is turned on, the voltage of the node N23 (data line Ld) is measured for the current value data Idata corresponding to all the 256 gradations, and the current value data You may update the table (memory) which shows the correspondence of Idata and voltage value data. The determination circuit 57b refers to the updated table and converts the current value data Idata output from the data latch circuit 53 into voltage value data, whereby the threshold voltage Vth of the light emission drive transistor T23 increases. Even in this case, it is possible to accurately determine that a human finger or a touch pen has touched the display panel 2a.

  The organic EL display device 1c is an example of the display device of the present invention, the scan driver 3 and the data driver 5c are examples of the drive circuit of the present invention, and the data latch circuit 53 and the DAIC 54c are the gradation current generators of the present invention. It is an example of a circuit.

<Modification of the first embodiment and the second embodiment>
For example, as shown in FIG. 30, a bypass switch 58 for bypassing the detection resistor 55 included in the data driver 5a and the data driver 5b may be provided.
When the touch panel function is not used, the bypass switch 58 is turned on to bypass the detection resistor 55 and directly apply the voltage output from the DAVC 54a to the node N23 (data line Ld).
On the other hand, when the touch panel function is used, the bypass switch 58 is turned off and the voltage output from the DAVC 54a is applied to the node N23 (data line Ld) via the detection resistor 55. In this case, the DAVC 54a outputs a voltage in consideration of a voltage drop generated in the detection resistor 55 so that a voltage equivalent to that when the bypass switch 58 is turned on is applied to the node N23 (data line Ld).
When the touch panel function is not used, the power consumed by the detection resistor 55 can be reduced by turning on the bypass switch 58.

Note that the configurations of the drive circuits and data drivers shown in the above embodiments are merely examples, and the present invention can be similarly applied to drive circuits and data drivers having different configurations.
The structure of the variable element Ev21 shown in the above embodiment is an example, and various other structures can be used.

  Further, in the first and third embodiments, the position detection circuit 61 has the scanning lines Ls1 to Lsn from which the scanning driver 3 has output scanning pulses, and the data driver 5a has output a display signal. Based on the data lines Ld1 to Ldm, the position where a human finger, a touch pen, or the like is in contact with the display panel 2a is specified. Based on ~ Lvn and the data lines Ld1 to Ldm from which the data driver 5a has output the display signal, the position at which a human finger, a touch pen or the like touches the display panel 2a may be specified.

  In each of the above embodiments, the display pixel 21 has a top emission structure. However, the display pixel 21 may have a bottom emission structure. However, in the case of the bottom emission structure, applying pressure to the display panel from the pixel substrate 113 side is referred to as applying pressure to the display panel.

  As described above, according to the present invention, in a display device having an organic EL element, when a human finger, a touch pen, or the like touches a display panel on a display pixel that drives and controls the organic EL element to display an image. A touch panel function for inputting a position can be added by adding a configuration for forming a variable element whose capacitance value or resistance value changes depending on the pressure. Since the display device according to the present invention does not have a stacked touch panel, the display device has a touch panel function, and can suppress a decrease in contrast of the displayed image, and is mounted for adding the touch panel function. The area can be reduced.

  Although the embodiments of the present invention have been described above, various modifications and combinations necessary for design reasons and other factors are described in the inventions described in the claims and the specific embodiments described in the embodiments of the invention. It should be understood that it falls within the scope of the invention corresponding to the examples.

It is a figure which shows an example of the organic electroluminescence display which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the scanning pulse output sequentially to a scanning line, and the voltage output sequentially to a power supply line. It is a figure which shows an example of a structure of the data driver which concerns on the 1st Embodiment of this invention. 1 is a diagram illustrating an example of a configuration of a pixel drive circuit and a data driver according to a first embodiment of the present invention. It is a figure which shows an example of the voltage or electric current of each part of the pixel drive circuit which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the electric current which flows through a pixel drive circuit in a selection period and a light emission period. It is an example of the top view of the display pixel which concerns on the 1st Embodiment of this invention. It is an example of the XI-XI cross section shown in FIG. It is a figure which shows an example of the shape of a variable element anode electrode. FIG. 4 is a diagram illustrating an example of voltages or currents of respective portions of the pixel drive circuit when a variable element starts to function as a capacitor in the pixel drive circuit according to the first embodiment of the present invention. FIG. 3 is a diagram showing an equivalent circuit of a main part when a variable element functions as a capacitor in the pixel drive circuit according to the first embodiment of the present invention. It is a figure which shows an example of the electric current which flows through a pixel drive circuit in a selection period and a light emission period when a variable element begins to function as a capacitor | condenser. In the pixel drive circuit according to the first embodiment of the present invention, it is a diagram showing an example of the voltage or current of each part of the pixel drive circuit when the capacitance value of the variable element further increases. It is a figure which shows an example of the electric current which flows through a pixel drive circuit in a selection period and the light emission period when the capacitance value of a variable element further increases. It is a figure which shows an example of the electric current which flows through a pixel drive circuit in a selection period and a light emission period when resistance of a variable element becomes very small. In the pixel drive circuit according to the first embodiment of the present invention, it is a diagram showing an example of the voltage or current of each part of the pixel drive circuit when the resistance of the variable element becomes extremely small. It is a figure which shows an example of the organic electroluminescence display which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of a structure of the pixel drive circuit and data driver which concern on the 2nd Embodiment of this invention. It is a figure which shows an example of the voltage output to the scanning pulse and power supply line which are sequentially output to a scanning line. It is a figure which shows an example of the voltage or electric current of each part of the pixel drive circuit which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the electric current which flows through a pixel drive circuit in a selection period and a light emission period. FIG. 10 is a diagram illustrating an example of voltages or currents of respective units of a pixel drive circuit when a variable element starts to function as a capacitor in the pixel drive circuit according to the second embodiment of the present invention. FIG. 10 is a diagram showing an equivalent circuit of a main part when a variable element starts to function as a capacitor in a pixel drive circuit according to a second embodiment of the present invention. In the pixel drive circuit according to the second embodiment of the present invention, it is a diagram showing an example of the voltage or current of each part of the pixel drive circuit when the capacitance value of the variable element further increases. It is a figure which shows the structure when the resistance of a variable element becomes very small in the pixel drive circuit and data driver which concern on the 2nd Embodiment of this invention. In the pixel drive circuit according to the second embodiment of the present invention, it is a diagram showing an example of the voltage or current of each part of the pixel drive circuit when the resistance of the variable element becomes extremely small. It is a figure which shows an example of the organic electroluminescence display which concerns on the 3rd Embodiment of this invention. It is a figure which shows an example of a structure of the data driver which concerns on the 3rd Embodiment of this invention. It is a figure which shows an example of a structure of the pixel drive circuit and data driver which concern on the 3rd Embodiment of this invention. It is a figure which shows an example of a structure of the data driver which concerns on the modification of the 1st Embodiment and 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b, 1c ... Organic EL display device, 21, 22 ... Display pixel, 2a, 2b ... Display panel, 21D, 22D ... Pixel drive circuit, 3 ... Scan driver, 4a, 4b ... Power supply driver, 5a, 5b, 5c Data driver 53 Data latch circuit 54a, 54b Digital voltage / analog voltage conversion circuit (DAVC) 54c Digital current / analog current conversion circuit (DAIC) 57a, 57b Determination circuit 61 Position detection circuit , Cs2, Cs3 ... capacitor, Ev21, Ev31 ... variable element, Ld1-Ldm ... data line, Ls1-Lsn ... scanning line, Lv1-Lvn ... power supply line, OEL ... organic EL element, T21 ... first input transistor, T22 ... Second input transistor, T23, T32 ... light emission drive transistor, T31 ... input transistor

Claims (10)

A display panel comprising a plurality of display pixels arranged near the intersections of a plurality of scanning lines and a plurality of data lines, each arranged in the row direction and the column direction;
By selecting each display pixel connected to the scan line by supplying a scan signal to each scan line, and supplying a display signal to each data line during a selection period for selecting each display pixel A drive circuit for driving each of the selected display pixels;
With
Each display pixel supplies a light emitting element and a driving current corresponding to the display signal supplied to the light emitting element via each data line, and a physical parameter changes according to a pressure applied from the outside. A pixel driving circuit including a variable element that modulates a potential according to a display signal supplied to each data line according to a change in the physical parameter,
The drive circuit supplies the display signal to each data line and detects the potential of each data line at a measurement timing set within the selection period via each data line, and the variable element Determining whether or not the potential of each of the data lines is modulated, and determining a column corresponding to the data line that is determined to be modulated as a position where pressure is applied,
A display device characterized by that. The drive circuit includes a gradation voltage generation circuit that generates a signal voltage having a voltage value corresponding to the display signal and outputs the signal voltage to each data line;
The determination circuit acquires the voltage value of each data line at the measurement timing, and compares the acquired voltage value with the voltage value of the data line when the potential is not modulated by the variable element. On the basis of the presence or absence of modulation of the potential,
The display device according to claim 1. The drive circuit includes a gradation current generation circuit that generates a signal current having a current value corresponding to the display signal and outputs the signal current to each data line;
The determination circuit acquires the voltage value of each data line at the measurement timing, and compares the acquired voltage value with the voltage value of the data line when the potential is not modulated by the variable element. On the basis of the presence or absence of modulation of the potential,
The display device according to claim 1. The variable element includes a capacitive element whose capacitance value changes as the physical parameter in accordance with an externally applied pressure,
The pixel driving circuit includes a capacitor that holds a voltage corresponding to the display signal,
In each of the display pixels, a circuit including the capacitor in the data line and the variable element are connected in parallel during the selection period.
The display device according to claim 1, wherein the display device is a display device.   The display device according to claim 4, wherein the capacitance value of the capacitive element increases with an increase in pressure applied from the outside. The variable element includes a resistance element whose electrical resistance value changes as the physical parameter according to a pressure applied from the outside,
Each display pixel connects the resistance element of the variable element between the data line and a predetermined reference voltage in the selection period.
The display device according to claim 1, wherein the display device is a display device. The display device according to claim 6, wherein the electrical resistance value of the resistance element decreases in accordance with an increase in pressure applied from the outside. The display panel includes a plurality of power supply lines that are paired with the scan lines and connected to the display pixels to which the corresponding scan lines are connected.
The drive circuit includes a power driver that outputs the predetermined reference voltage to the power lines.
The picture element drive circuit,
The control terminal is connected to one electrode of the capacitor, one end of the conductive passage is connected to one electrode of the anode electrode and the variable element of the light emitting element and the other electrode of the capacitor, the other end of the current path A first transistor connected to the power supply line;
A control terminal is connected to the scanning line, one end of a current path is connected to the control terminal of the first transistor and one electrode of the capacitor, and the other end of the current path is connected to the power line and the first transistor. A second transistor connected to the other end of the current path;
A control terminal is connected to the scan line, one end of the current path is connected to the data line, and the other end of the current path is the other electrode of the capacitor, one electrode of the variable element, and the current of the first transistor. A third transistor connected to one end of the path and the anode electrode of the light emitting element;
Including
The predetermined reference voltage is applied to the other electrode of the variable element;
The display device according to claim 6, wherein the display device is a display device. The display panel includes a plurality of power supply lines that are paired with the scan lines and connected to the display pixels to which the corresponding scan lines are connected.
The drive circuit includes a power driver that outputs the predetermined reference voltage to the power lines.
Each pixel driving circuit includes:
A control terminal is connected to one electrode of the capacitor and one electrode of the variable element, one end of the current path is connected to the other electrode of the capacitor and the anode electrode of the light emitting element, and the other end of the current path is A first transistor connected to the power line;
A control terminal is connected to the scan line, one end of a current path is connected to the data line, and the other end of the current path is one of the control terminal of the first transistor, one electrode of the capacitor, and one of the variable elements. A second transistor connected to the electrode;
Including
The predetermined reference voltage is applied to the other electrode of the variable element;
The display device according to claim 6, wherein the display device is a display device. The drive circuit is
A scan driver connected to the plurality of scan lines and sequentially supplying the scan signals for sequentially selecting the display pixels to the scan lines;
When the determination circuit determines that the potential is modulated, the row position corresponding to the scan line from which the scan driver outputs the scan signal and the column position specified by the determination circuit A position detection circuit for identifying a position on the display panel to which pressure is applied,
The display device according to claim 1, comprising:

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