JP6635719B2 - Optical sensor circuit and display device provided with optical sensor circuit - Google Patents

Description

  The present invention relates to a method for driving a display device such as a liquid crystal display device or an organic EL display device, and more particularly, to a pixel driving circuit technology when an optical sensor is manufactured on a panel substrate.

  Due to the sophistication of mobile devices, the sophistication of wireless communication environments, and the sophistication of fingerprint authentication software, mobile devices that can perform fingerprint authentication from mobile terminals have begun to be sold. In such a technical field, a technology related to a display device equipped with an optical sensor is a key point.

  As a conventional technique, there is a display device provided with a highly sensitive optical sensor in a pixel area (for example, see Patent Document 1). Further, in a display device using only a single-channel thin film transistor, there is a display device that reduces cost without using a PIN-type photodiode as an optical sensor when an optical sensor is incorporated in a pixel (for example, see Patent Document 2). ).

  Furthermore, the pixels including the light-emitting circuit and the light-receiving circuit are arranged in rows and columns so that image information can be captured without providing a CCD sensor, CMOS sensor, or touch panel. (For example, see Patent Document 3)

International Publication No. 2011-0655558 JP 2011-39806 A JP 2005-148285 A

However, the related art has the following problems.
By enabling the optical sensor to be built into the display surface, it is possible to reduce costs by reducing the number of components and to provide new functions to customers. Therefore, there is a need for an optical sensor circuit system that does not require special control and can suppress a decrease in aperture ratio. On the other hand, products with a built-in sensor on the display surface have not yet been released.

  The display device according to Patent Literature 1 has a configuration in which a Reset signal RST and a Read Out signal RES are added separately from a gate line, and a sensor is driven with a power source and timing different from those of the gate line. Therefore, there has been a problem that control of the sensor circuit is complicated and a dedicated driving system (incorporation into a dedicated IC or DDI) is required.

  The display device according to Patent Document 2 has a configuration in which a CLK2 signal is added to Reset, an SGND signal is added to Read Out, and a CLK1 signal is added to a power supply line. In this configuration, each signal line is different from the gate line control, and there is a problem that the circuit configuration and control are complicated.

  Further, the display device according to Patent Document 3 is an AM type sensor circuit using an organic EL for a light emitting and a light receiving element, and newly includes three control signals, two bias potential lines, and one output line. The configuration has been added. Therefore, even with this configuration, there is a problem that the circuit is complicated and a problem that the aperture ratio is reduced.

That is, each of the prior arts has the following three points as causes of problems.
(Cause 1) It is difficult to achieve both image signal input for display and readout of output data from the optical sensor.
(Cause 2) A gate line is not used as a control line.
(Cause 3) A data line is not used as the Read Out line.

  In other words, the conventional display device does not have a method that can easily control (Reset, Read Out) the optical sensor, and it is difficult to achieve both input of a video signal for display and reading of output data from the optical sensor. In addition, a drive signal and an input / output signal dedicated to the sensor are required, which complicates the circuit configuration and control, and lowers the aperture ratio.

  The present invention has been made in order to solve the above-described problems, and an optical sensor circuit capable of suppressing a decrease in aperture ratio and a display device including the optical sensor circuit without adding a new wiring. The purpose is to gain.

  In the photosensor circuit according to the present invention, a photosensor is embedded in a specific pixel of the display device, and when n is an integer of 1 or more, the (n + 1) th gate line G (n + 1) is reset. An optical sensor circuit that uses a gate line G (n) of the n-th line as a readout signal as a readout signal and uses the same wiring as a data line used in a display mode of a display device to form a signal in a specific pixel. The detection signal from the embedded optical sensor can be output in the sensor mode.

  According to the present invention, there is provided an optical sensor circuit that uses a gate line G (n + 1) as a reset signal and uses the gate line G (n) as a read signal. It has a circuit configuration for outputting. As a result, it is possible to obtain an optical sensor circuit capable of suppressing a decrease in aperture ratio and a display device including the optical sensor circuit without adding a new wiring.

FIG. 3 is a circuit diagram of a photosensor circuit in a region corresponding to one pixel of the display device according to the first embodiment of the present invention. FIG. 2 is a diagram showing waveforms at the time of sensing and at the time of reading of the optical sensor circuit shown in FIG. 1 according to the first embodiment of the present invention. FIG. 9 is a circuit diagram of a photosensor circuit in a region corresponding to one pixel of a display device according to a second embodiment of the present invention. FIG. 14 is a circuit diagram of a photosensor circuit in a region corresponding to one pixel of a display device according to a third embodiment of the present invention. FIG. 15 is a circuit diagram of a photosensor circuit in a region corresponding to one pixel of a display device according to a fourth embodiment of the present invention. FIG. 15 is a schematic diagram of a display device to which an optical sensor circuit according to Embodiment 5 of the present invention is applied. FIG. 15 is a diagram showing a driving waveform of a display device to which the optical sensor circuit according to the fifth embodiment of the present invention is applied.

An optical sensor circuit and a display device provided with the optical sensor circuit according to the present invention have the following two technical features.
(Feature 1) Sensor circuit and control method without adding a new control line (Feature 2) Read Out method for realizing Feature 1 Therefore, the optical sensor circuit of the present invention and the display device including the optical sensor circuit are preferably used. Embodiments will be described below with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram of an optical sensor circuit in a region corresponding to one pixel of the display device according to Embodiment 1 of the present invention. The optical sensor circuit according to the first embodiment shown in FIG. 1 has the following configuration and features.
The pixel circuit includes one photodiode PD, one capacitor Css, and two TFTs Tsel and Tread.
-Each subscript of Vsst, Vsvol, Vros, and Vroll has the following meaning.
Vsst: Sense Start
Vsvol: Sense Voltage
Vros: Read Out Source
Vroll: Read Out Line

Reset is started when the gate line G (n + 1) rises, and Read Out is started when the gate line G (n) rises.
At the time of sensor output, a certain Vsvol potential is supplied to Vros, and a potential between this potential and the Vss potential is output as OUT.

  Next, the driving of the display mode for executing the display processing and the driving of the sensor mode for executing the detection processing by the sensor will be described.

<During display mode>
RGB or RGBW video data is input to the video pixel. Although not shown in FIG. 1, video data for an adjacent video pixel is input to two input / output lines (Vros and Vroll) of the sensor pixel, or the output line measurement is set to Floating. .

<In sensor mode>
The control of the image pixels of the sensor unit will be changed. That is, RGB or RGBW video data is input to the image pixels of the display unit, as in the display mode.

  On the other hand, “H” is input to the image pixel of the sensor unit, and this input becomes the power supply of the sensor pixel. The input line for the sensor pixel is used as a Read Out line. Further, the gate of the Read Out TFT (Tro) shown in the lower part of FIG. 1 is connected to the Bias potential Vbias, and the source is connected to the low potential Vss.

FIG. 2 is a diagram showing waveforms at the time of sensing and at the time of reading in the sensor mode of the optical sensor circuit shown in FIG. 1 according to the first embodiment of the present invention. The reset operation is performed by resetting the node Vs to Vgh−Vthpd by the rise of the gate line G (n + 1), and the initial value Vsini of the node Vs is expressed by the following equation.
Vsini = Vgh−Vthpd

  Thereafter, the photodiode enters a reverse bias state, a current according to the amount of light flows through the gate line G (n + 1), and the potential of the node Vs decreases. This state is represented as “Sensing period” in FIG.

  The state of the “Sensing period” continues until the gate line G (n) is activated at the next timing, and at the rise of the gate line G (n), the potential corresponding to the gate potential (Vs) of the TFT is changed. Is output.

  As described above, according to the first embodiment, the optical sensor circuit uses the gate line G (n + 1) as the reset signal and uses the gate line G (n) as the read signal, and uses the same wiring as the data line. Thus, a configuration for outputting a detection signal by an optical sensor is realized. As a result, it is possible to obtain a photosensor circuit capable of suppressing a decrease in aperture ratio without adding a new wiring, and a display device including the photosensor circuit.

Embodiment 2 FIG.
FIG. 3 is a circuit diagram of a photosensor circuit in a region corresponding to one pixel of the display device according to the second embodiment of the present invention. The circuit configuration of the optical sensor circuit according to the second embodiment shown in FIG. 3 is the same as the circuit configuration of FIG. 1 according to the first embodiment, but the control method of the Read Out TFT (Tro) is different. I have.

Note that the respective subscripts of the voltages Vrocont and Vsp newly added in FIG. 3 have the following meanings.
Vrocont: Read Out Control
Vsp: Sense Pulse

The optical sensor circuit according to the second embodiment has the following configuration and features.
The control signal Vrocont is input to the gate of the Read Out TFT (Tro), and a certain pulse waveform (Vsp) is input to the source.
The potential range of the output (OUT) value can be controlled by inputting Vsp.

  The driving method conforms to the first embodiment, and the description is omitted.

  As described above, according to the second embodiment, the photosensor circuit uses the gate line G (n + 1) as the reset signal and uses the gate line G (n) as the read signal, and uses the same wiring as the data line. Thus, a configuration for outputting a detection signal by an optical sensor is realized. As a result, it is possible to obtain an optical sensor circuit capable of suppressing a decrease in aperture ratio without adding a new wiring, and a display device including the optical sensor circuit.

  Further, by adopting a configuration in which a pulse waveform of a predetermined potential is input to the Read Out TFT, a further effect that the potential range of the output (OUT) value can be controlled can be obtained.

Embodiment 3 FIG.
FIG. 4 is a circuit diagram of a photosensor circuit in a region corresponding to one pixel of the display device according to Embodiment 3 of the present invention. The optical sensor circuit according to the third embodiment shown in FIG. 4 has the following configuration and features different from those of the first and second embodiments.
The pixel circuit includes one photodiode PD, one capacitor Css, and two TFTs Tsel and Tread. Here, the connection position of the capacitor Css is different from the first and second embodiments. Specifically, the capacitor Css in the third embodiment is connected between the gate and the drain of Tread.

In addition, the circuit operation and the drive waveform are in accordance with the first and second embodiments.
As in the second embodiment, the control signal Vrocont is input to the gate of the Read Out TFT (Tro), and a certain pulse waveform (Vsp) is input to the source.
The potential range of the output (OUT) value can be controlled by inputting Vsp.

  As described above, according to the third embodiment, the same effect as that of the second embodiment can be obtained by the optical sensor circuit having the configuration in which the connection position of the capacitor is changed.

Embodiment 4 FIG.
FIG. 5 is a circuit diagram of a photosensor circuit in a region corresponding to one pixel of the display device according to the fourth embodiment of the present invention. The optical sensor circuit according to the fourth embodiment shown in FIG. 5 has the following configuration and features different from the first to third embodiments.
The pixel circuit includes one photodiode PD, one capacitor Css, and two TFTs Tsel and Tread. Here, the connection position of the capacitor Css is different from the first to third embodiments. Specifically, the capacitor Css in the fourth embodiment is connected between the gate of Tread and the gate line G (n).

In addition, the circuit operation and the drive waveform are the same as in the first to third embodiments.
As in the second and third embodiments, the control signal Vrocont is input to the gate of the Read Out TFT (Tro), and a certain pulse waveform (Vsp) is input to the source.
The potential range of the output (OUT) value can be controlled by inputting Vsp.

  As described above, according to the fourth embodiment, the same effects as those of the second and third embodiments can be obtained by the optical sensor circuit having the configuration in which the connection position of the capacitor is changed.

Embodiment 5 FIG.
In Embodiment 5, a case is described in which the optical sensor circuits described in Embodiments 1 to 4 are applied to a display device. In particular, in the following specific example, a case will be described in which an optical sensor circuit including a Read Out control signal Vrocont is applied to a display device.

  FIG. 6 is a schematic diagram of a display device to which the optical sensor circuit according to Embodiment 5 of the present invention is applied. Specifically, the display device shown in FIG. 6 is a schematic diagram in which the upper part of one display is driven only in the display mode, and the lower part is activated in the display mode and the sensor output mode.

  FIG. 7 is a diagram showing a driving waveform of a display device to which the optical sensor circuit according to the fifth embodiment of the present invention is applied. In the upper region driven only in the display mode, the gate lines GL_1 to GL_x are sequentially driven.

  On the other hand, in the lower region driven in the display mode and the sensor output mode, the gate lines GL_x + 1 to GL_Dummy are sequentially driven, and the sensor output start signal Vsst and the Read Out control signal Vrocont are activated corresponding to this region. This shows how the sensor output is started by the conversion.

As described above, according to the fifth embodiment, the following effects can be obtained by using the display device to which the optical sensor circuit of the present invention is applied.
(Effect 1) Since the gate lines (G (n), G (n + 1)) are used for controlling the optical sensor, a special driving IC is not required.
(Effect 2) By using the data line for the sensor power supply and the output, no additional wiring is required, and the decrease in the aperture ratio can be minimized.

  Various types of photodiodes, such as a PIN diode, an amorphous diode, and an n-type diode, can be applied to the photodiodes used in the optical sensor circuits according to Embodiments 1 to 5 described above.

  PD photodiode, Css capacitor, Tsel, Tread, Tro Thin film transistor (TFT).

Claims (10)

When n is an integer of 1 or more,
A photodiode embedded in a specific pixel of the display device and connected to the (n + 1) -th gate line G (n + 1);
A first thin film transistor (Tsel) and a second thin film transistor (Tread) connected between the first data line (Vros) and the second data line (Vroll), wherein the first thin film transistor (Tsel) is connected to the first thin film transistor (Tsel); A first thin film transistor (Tsel) and a second thin film transistor (Tread) whose gates are connected to an n-th gate line G (n);
With
An optical sensor circuit that uses a signal of a gate line G (n + 1) of an (n + 1) th line as a reset signal and uses a signal of a gate line G (n) of an nth line as a read signal,
Photosensor circuit that can be output by using the second data lines to be used in a display mode of the display device (Vrol), a detection signal by the pre-SL photodiodes in the sensor mode. The first data line (Vros) is used as a power supply wiring of the photosensor circuit by inputting an “H” signal, and the second data line (Vroll) is used as an output wiring of the detection signal. The optical sensor circuit according to claim 1. Output wiring of the detection signal,
When the detection data output of the photodiode is not performed, video data is input or set to a floating state,
The optical sensor circuit according to claim 1, wherein when the detection data of the photodiode is output, a data potential from the photodiode is input. The apparatus further includes a capacitor connected to the photodiode and the second thin film transistor (Tread) in the specific pixel .
The optical sensor circuit according to claim 1. The optical sensor circuit according to claim 1, wherein the photodiode is a PIN diode. The optical sensor circuit according to claim 1, wherein the photodiode is an amorphous diode. The optical sensor circuit according to claim 1, wherein the photodiode is an n-type diode. The photodiode is connected to a node;
The second thin film transistor is connected to the node;
The photodiode resets the potential of the node to an initial value, starts sensing in response to a reset signal, and outputs a detection signal in accordance with the potential of the node.
The optical sensor circuit according to claim 1. A third thin film transistor (Tro) connected to the second thin film transistor (Tread), wherein a bias voltage (Vbias) or a control voltage (Vrocont) is input to a gate of the third thin film transistor (Tro); The optical sensor circuit according to claim 1. Display device including a light sensor circuit as claimed in any one of claims 1 to 9.

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