JP2007034006A - Organic electroluminescent display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescence display device which can make the organic EL panel itself obtain a touch panel function. <P>SOLUTION: This is an organic electroluminescent (EL) display device which has a column signal drive circuit 34 having data lines D, a row scanning drive circuit 36 having selection lines W, and a display panel 32 having pixels Px. The pixel has an organic EL element 8, a thin organic film transistor 10 for driving, a switching organic thin film transistor 11 for selection, and a thin organic film transistor 38 for detecting positions. The transistor for detecting the position has its one terminal connected to the input or output of the organic EL element with the other terminal connected to the column signal drive circuit. When a pixel receives an impact from the outside, it detects the voltage change in the thin organic film transistor to detect the position, and specifies the position of the pixel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  In recent years, as a future display device, a flexible display device having excellent portability and accommodating property has been actively developed. In particular, an organic thin film transistor (hereinafter referred to as “organic TFT”) is formed on a flexible substrate such as a thin plastic substrate. : [Thin Film Transistor]), organic electroluminescence element (hereinafter also referred to as “organic EL element”), and switching organic thin film transistor element (hereinafter also referred to as “organic TFT element”) for selection. Devices (hereinafter also referred to as “organic EL display devices”) are known.

FIG. 5 shows a schematic diagram of one pixel of the organic EL display device, and FIG. 6 shows a circuit diagram of one pixel of the organic EL display device. In this organic EL display device 2, an insulating film 6 made of, for example, SiO ₂ is formed on a thin flexible substrate 4 made of, for example, a plastic substrate, and the organic EL element 8 and the insulating film 6 are formed on the insulating film 6. The driving organic TFT element 10 for driving it and the switching organic TFT element 11 for switching the driving organic TFT element 10 are provided in parallel. One pixel Px is formed by the above structure, and the pixels Px are arranged in a matrix in the vertical and horizontal directions. The organic EL element 8 is formed by interposing the light emitting layer 16 and the hole transport layer 18 between the upper and lower transparent electrodes 12 and 14, but is not limited to this configuration, and has various structures. Can be used.

  In the circuit configuration of the one pixel Px described above, as shown in FIG. 6, the input side of the driving organic TFT 10 is connected to the power supply line 20, and the output side is connected to one electrode of the organic EL element 8. The The other electrode of the organic EL element 8 is grounded. The gate of the driving organic TFT 10 is connected to the output of the switching organic TFT 11 for selection. The input of the switching organic TFT 11 is connected to the data line D, and the gate is connected to the selection line W. Further, a storage capacitor 22 (not shown in FIG. 5) is connected between the power line 20 and the gate of the driving organic TFT 10 so that data can be stored for a certain period.

  By the way, recently, an apparatus in which the above-described organic EL display apparatus has a touch panel function has been proposed (Patent Document 1). This organic EL display device having a touch panel function is configured, for example, by attaching a touch panel that operates, for example, by a resistance change method or a switching method, to the front surface or back surface of the organic EL panel in the passage, as shown in Patent Document 1 above. In particular, the structure in which the touch panel is attached to the back side of the organic EL panel has a characteristic that the display quality is superior to the structure to be attached to the front side.

JP 2001-343908 A

However, as described above, in order to provide the touch panel function, the configuration in which the touch panel is attached to the organic EL panel not only increases the number of parts as a whole, but also requires the steps of attaching both panels. The number of assembly steps will also increase.
In addition, the resistance change type touch panel has a poor temperature characteristic, and there is a problem that the reliability is insufficient in use in a vehicle, for example. Furthermore, in the method of attaching the touch panel to the back surface side of the organic EL panel, the pressing force is transmitted to the touch panel side via the organic EL panel, so the pressing force detection sensitivity may not be sufficient. .
The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide an organic EL display device capable of not only reducing the number of components but also improving detection sensitivity and temperature characteristics by providing the organic EL panel itself with a touch panel function. It is in.

  As a result of diligent research on the organic EL element, the present inventor changes its electrical characteristics in response to physical deformation caused by an external force (pressing force), and the change in the electrical characteristics is detected positionally. By doing so, the present invention has been achieved by obtaining the knowledge that a touch panel function can be provided.

The invention according to claim 1 is a column signal driving circuit having a plurality of data lines in the column direction, a row scanning driving circuit having a plurality of selection lines intersecting with the plurality of data lines in the row direction, and the plurality of data A display panel having each pixel arranged in a matrix corresponding to each intersection of the line and the plurality of selection lines, wherein the pixel comprises an organic electroluminescent display device. Sense element, organic thin film transistor for driving to drive the organic electroluminescent element, switching organic thin film transistor for selection to select the organic thin film transistor for driving, and organic thin film transistor for position detection to detect the position of the pixel And the organic thin film transistor for position detection has two terminals and one And one of the terminals is connected to an input side or an output side of the organic electroluminescence element, the other terminal is connected to the column signal driving circuit, and the gate is connected to the row scanning driving circuit. When the pixel receives an external force, the change in the current flowing through the driving organic thin film transistor corresponding to the pixel is changed to the voltage in the organic thin film transistor for position detection corresponding to the pixel. The organic electroluminescence display device is characterized in that the position of the pixel is specified by detecting a change in the voltage by the column signal driving circuit.
In this case, for example, as defined in claim 2, the organic electroluminescent display device has flexibility.

According to the organic EL display device of the present invention, the organic EL panel itself can be provided with a touch panel function, and not only the number of components can be reduced but also the detection sensitivity and temperature characteristics can be improved.
In addition, the number of parts is reduced, and a pasting process for pasting panels together is not necessary, so that the number of assembly processes can be reduced accordingly.

Hereinafter, an embodiment of an organic EL display device according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view showing a pixel arrangement of an organic EL display device according to the present invention, FIG. 2 is a schematic diagram showing one pixel of the organic EL display device of the present invention, and FIG. 3 is one pixel in the organic EL display device. FIG. 1 to 3, the same components as those shown in FIGS. 5 and 6 will be described with the same reference numerals.

  As shown in FIG. 1, the organic EL display device 30 of the present invention has a display panel 32, and a plurality of pixels Px are arranged in a matrix in the vertical and horizontal directions. A column signal driving circuit 34 and a row scanning driving circuit 36 are arranged on one side of the display panel 30 and the other side orthogonal thereto. A plurality of data lines D1 to Di extending in the column direction extend from the column signal driving circuit 34 toward the display panel 32, and from the row scanning driving circuit 36 in the row direction toward the display panel 32. A plurality of selection lines W1 to Wk that extend in a straight line are extended, and the intersection of both lines is the pixel Px as described above.

Further, as a feature of the present invention, from the column signal driving circuit 34, the position detection data lines Y1 to Yi extend in the column direction corresponding to the data lines D1 to Di, and the row scanning driving is performed. From the circuit 36, selection lines X1 to Xk for position inspection extend corresponding to the selection lines W1 to Wk, and are connected to the corresponding pixels.
The display panel 32 is connected to a power line (not shown) corresponding to each pixel Px and can supply power for display. The column signal drive circuit 34 and the row scanning drive circuit 36 as well as the display panel 32 or the display panel 32 are based on the flexible substrate 4 such as a flexible plastic substrate as described in FIG. , Formed on this base. In addition to the organic EL element 8, the driving organic TFT 10, and the switching organic TFT 11 for selection, the one pixel Px includes an organic for position detection as a feature of the present invention as shown in FIGS. A thin film transistor (hereinafter also referred to as “organic TFT”) 38 is provided. The organic TFT 38 for position detection is further provided side by side as shown in FIG. 2 in the configuration shown in FIG.

  Here, a specific circuit of one pixel is formed as shown in FIG. FIG. 3A shows the first embodiment, and FIG. 3B shows the second embodiment. Here, the lines D1 to Di, Y1 to Yi, W1 to Wk, and X1 to Xk are represented as “D”, “Y”, “W”, and “X”, respectively. That is, the input side of the driving organic TFT 10 is connected to the power supply line 20, and the output side is connected to one electrode of the organic EL element 8. The other electrode of the organic EL element 8 is grounded. The gate of the driving organic TFT 10 is connected to the output of the switching organic TFT 11 for selection. The input of the switching organic TFT 11 is connected to the data line D, and the gate is connected to the selection line W. A storage capacitor 22 (not shown in FIG. 2) is connected between the power supply line 20 and the gate of the driving organic TFT 10 so that data can be held for a certain period.

One of the input organic TFTs 38 for position detection, which is a feature of the present invention, is connected to the output side of the driving organic TFT 10. Specifically, in the case shown in FIG. 3A, one input of the organic TFT 38 for position detection is between the output side of the organic TFT 10 for driving and the input side of the organic EL element 8. It is connected to the. 3B, one input of the organic TFT 38 for position detection is connected to the output side of the organic EL element 8 via a resistor 40 and connected to the input side of the resistor 40. Has been.
The output of the organic TFT 38 for position detection is connected to the data line Y for position detection. Further, the gate of the organic TFT 38 for position detection is connected to the selection line X for position scanning.

  In the organic EL display device 30 configured as described above, display data signals are sequentially applied from the column signal driving circuit 34 to the data lines D1 to Di, and the scanning signal from the row scanning driving circuit 36 is used. When the pixel Px is selected, an image based on the data is displayed on the organic EL element 8 of the selected pixel. This is the same for the conventional apparatus.

Now, if the current flowing through the driving organic TFT 10 changes due to deformation due to an external force, for example, a pressing force, as will be described later, the fluctuation amount is the position detection data of the organic TFT 38 for position detection. A change in voltage appears on the line Y, and this is detected on the column signal drive circuit 34 side, whereby the position of the pixel can be specified. In this case, a scanning signal is periodically applied to the position scanning selection line X from the row scanning driving circuit 36 side, and this pixel can be specified as described above.
Here, a change in electrical characteristics with respect to the deformation of the driving organic TFT 10 will be described. FIG. 4 is a graph showing changes in electrical characteristics with respect to deformation of the driving organic TFT. In FIG. 4, the horizontal axis indicates the deformation (= curvature radius), and the vertical axis indicates changes in current and mobility.

  As is apparent from FIG. 4, the mobility, that is, the current flowing through the transistor, varies greatly by bending and deforming the driving organic TFT 10. Therefore, as apparent from the circuit shown in FIG. 3, this current flows through the organic EL element 8 having the resistance element and the resistor 40 (in the case of FIG. 3B). The voltage change at both ends or the voltage change at both ends of the resistor 40 can be detected by the data line Y for position detection, and the position of the deformed pixel Px of the driving organic TFT 10 can be specified. In this way, the organic EL panel can have a touch panel function.

As described above, the organic EL panel itself can be provided with a touch panel function, so that not only the number of components can be reduced but also the detection sensitivity and temperature characteristics can be improved.
In addition, the number of parts is reduced, and a pasting process for pasting panels together is not necessary, so that the number of assembly processes can be reduced accordingly.

It is a top view which shows the pixel arrangement | sequence of the organic electroluminescence display which concerns on this invention. It is the schematic which shows one pixel of the organic electroluminescent display apparatus of this invention. It is a circuit diagram which shows one pixel in an organic electroluminescence display. It is a graph which shows the change of the electrical property with respect to a deformation | transformation of the organic TFT for a drive. It is the schematic which shows one pixel of the conventional organic EL display apparatus. The circuit diagram of one pixel of the conventional organic electroluminescence display is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 ... Flexible board | substrate, 8 ... Organic electroluminescent (EL) element, 10 ... Organic thin-film transistor (TFT) for a drive, 11 ... Switching organic thin-film transistor (TFT) for selection, 30 ... Organic electroluminescent (EL) element, 32: Display panel, 34: Column signal drive circuit, 36: Row scanning drive circuit, 38: Organic thin film transistor (TFT) for position detection, 40 ... Resistance, Px ... Pixel, D, D1-Di ... Data line, W, W1-Wk ... selection line, Y, Y1-Yi ... position detection data line, X, X1-Xk ... position scanning selection line.

Claims (2)

A column signal drive circuit having a plurality of data lines in the column direction;
A row scanning drive circuit having a plurality of selection lines intersecting the plurality of data lines in a row direction;
A display panel having each pixel arranged in a matrix corresponding to each intersection of the plurality of data lines and the plurality of selection lines;
An organic electroluminescence display device comprising:
The pixel is
An organic electroluminescence element;
An organic thin film transistor for driving to drive the organic electroluminescence element;
A switching organic thin film transistor for selection for selecting the organic thin film transistor for driving; and
An organic thin film transistor for position detection for detecting the position of the pixel,
The organic thin film transistor for position detection has two terminals and one gate, one of the terminals is connected to the input side or the output side of the organic electroluminescence element, and the other terminal is the column signal. Connected to the driving circuit, the gate is connected to the row scanning driving circuit,
When the pixel receives an external force, a change in current flowing in the driving organic thin film transistor corresponding to the pixel is defined as a voltage change in the position detecting organic thin film transistor corresponding to the pixel. The position of the pixel is specified by detecting the change in the column signal driving circuit. The organic electroluminescence display device according to claim 1, wherein the organic electroluminescence display device has flexibility.

Images