JP6276685B2 - Photosensor pixel circuit for display device and display device - Google Patents

Description

  The present invention relates to a photosensor pixel circuit of a liquid crystal display device or an organic EL display device, and more particularly to a technique for incorporating a photosensor for an image scanner in a display display surface.

  Due to the high performance of mobile devices, the advancement of wireless communication environment, and the advancement of fingerprint authentication S / W, mobile devices that can perform fingerprint authentication from mobile terminals have begun to be sold. Various conventional techniques for controlling an optical sensor used in an image scanner such as fingerprint authentication have been proposed (see, for example, Patent Documents 1 and 2).

  FIG. 7 is a diagram showing a conventional pixel circuit in Patent Document 1, and FIG. 8 is an explanatory diagram showing operation waveforms of each part of the conventional pixel circuit in Patent Document 1. In FIG. According to Patent Document 1, a reset signal RST and a read signal RES are added separately from the gate line. These two signals are driven by a power source and timing different from the gate line.

  According to Patent Document 1, when reading a signal from a sensor, one of the data lines is used as a power source, and the other data line is used as a read line. Therefore, Patent Document 1 uses a data line as a wiring at the time of reading, so that no new wiring is added and a decrease in aperture ratio can be suppressed.

  FIG. 9 is a diagram showing a conventional pixel circuit in Patent Document 2, and FIG. 10 is an explanatory diagram showing operation waveforms of each part of the conventional pixel circuit in Patent Document 2. In FIG. According to Patent Document 2, the CLK2 signal is added to reset, the SGND signal is added to reading, and the CLK1 signal is added to the power supply line, thereby realizing control of the optical sensor.

  In Patent Document 2, each added signal line is different from the control of the gate line. The readout system is driven using the CLK1 and SOUT lines.

International Publication 2011/065556 JP 2011-39806 A

However, the prior art has the following problems.
Patent Documents 1 and 2 both propose a different control method with substantially the same element configuration. However, in Patent Document 1, since the drive amplitude and timing are different from those of the gate line, the control of the optical sensor is complicated, and a dedicated drive system (incorporation into a dedicated IC or DDI) is required.

  Further, Patent Document 2 requires additional wiring for controlling the optical sensor, and there is a problem that the additional wiring reduces the aperture ratio and decreases display performance (resolution, luminance, power consumption).

  Thus, in a display device using an optical sensor, simplification of control and suppression of aperture ratio reduction can be cited as problems. And in order to solve such a subject, it is possible to incorporate a sensor in a display display surface. However, at present, such a product having a sensor built in the display surface has not yet been released.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a photosensor pixel circuit for a display device and a display device that can realize simplification of control and suppression of aperture ratio reduction. To do.

An optical sensor pixel circuit for a display device according to the present invention is an optical sensor pixel circuit for a display device in which an optical sensor is incorporated in at least a part of a display surface, and the n-th line light in which the optical sensor is incorporated. In each of the sensor pixels, the gate line (n + 1) is used as a reset signal as the control line of the photosensor, the gate line (n) is used as a readout signal, and the output line of the photosensor is a pair different from the data line. The wiring is newly formed with a transparent electrode, and a detection signal from the photosensor is output . Each photosensor pixel has a cathode connected to the gate line (n) and an anode connected to the gate line (n + 1). One photodiode for detecting the amount of light, the gate is connected to the gate line (n), and each of the source and drain is connected between a pair of wirings. Those configured to include a single thin film transistor which outputs a detection signal by the photo diode in response to a read signal input to the gate via the gate line (n).

  According to the present invention, the use of the gate line for the control (reset, readout) of the optical sensor eliminates the need for a special drive IC. Furthermore, a new additional wiring is not required for the control line, and a transparent wiring is used for the output line, thereby preventing the aperture ratio from being lowered. By adopting such a configuration, it is possible to incorporate an optical sensor on the display surface, and it is possible to reduce costs by reducing the number of parts and provide new functions to customers. As a result, it is possible to obtain a photosensor pixel circuit for a display device and a display device that can realize simplification of control and suppression of reduction in aperture ratio.

It is a block diagram of the photo sensor pixel circuit in Embodiment 1 of this invention. It is the figure which showed the waveform of each signal at the time of sensing and reading of the optical sensor pixel circuit in Embodiment 1 of this invention. 1 is a schematic diagram illustrating an overall configuration of a display in Example 1. FIG. FIG. 4 is a diagram illustrating drive waveforms in each part of the display illustrated in FIG. 3 according to the first embodiment. 6 is a pixel configuration diagram of a photosensor pixel circuit in Embodiment 2. FIG. FIG. 10 is a cross-sectional view showing the arrangement of sensor output wirings of the photosensor pixel circuit in Example 3. FIG. 10 is a diagram showing a conventional pixel circuit in Patent Document 1. It is explanatory drawing which showed the operation waveform of each part of the conventional pixel circuit in patent document 1. FIG. FIG. 10 is a diagram showing a conventional pixel circuit in Patent Document 2. FIG. 10 is an explanatory diagram showing operation waveforms of each part of a conventional pixel circuit in Patent Document 2.

  Hereinafter, preferred embodiments of a photosensor pixel circuit and a display device for a display device according to the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a photosensor pixel circuit according to Embodiment 1 of the present invention. The photosensor pixel circuit shown in FIG. 1 includes one photodiode PD that is a photosensor, one capacitor Css, and one thin film transistor M1.

  In the photosensor pixel circuit as shown in FIG. 1, the photodiode PD has a cathode connected to the gate line (n) via the capacitor Css and an anode connected to the gate line (n + 1), and detects the amount of light. . The thin film transistor M1 has a gate connected to the gate line (n) through the capacitor Css, and a source and a drain connected between the pair of wirings Vrov and Vrol.

  The photodiode PD starts reading when the gate (n) rises, and is reset when the gate (n + 1) rises. At the time of optical sensor output, a certain Vsvol potential (High potential) is supplied to Vrov, and a potential between this potential and the Vsro potential is output as OUT.

  Along with the use of the optical sensor, a pair of wires of Vrov and Vrol will be newly added. These wirings are floating except at the time of sensor output.

FIG. 2 is a diagram showing waveforms of signals during sensing and reading in the photosensor pixel circuit according to Embodiment 1 of the present invention. As the gate line Gate (n + 1) rises, the initial value of the node Vs is reset to Vgh−Vthpd.
Vsini = Vgh−Vthpd

  Thereafter, the photodiode PD is in a reverse bias state, a current according to the amount of light flows to the gate line Gate (n + 1), and the potential of the node Vs decreases. This state continues until the next gate line Gate (n) is activated, and a potential corresponding to the gate potential Vs of the thin film transistor M1 is output from OUT at the rise of the gate line Gate (n).

The characteristics of the photosensor pixel circuit of FIG. 1 are summarized as follows.
(Feature 1) A special drive IC is not required by diverting the gate line to the control (reset, readout) of the optical sensor. As a result, an increase in the number of parts can be prevented and simplification of control can be realized.

  (Feature 2) New additional wiring is not required for the control line, and Vrov and Vrol are newly added for the output line. However, regarding these additional wirings, a decrease in the aperture ratio can be prevented by using transparent wiring.

  Next, three examples in which the photosensor pixel circuit having such characteristics is applied will be described in detail.

[Example 1]
FIG. 3 is a schematic diagram illustrating the overall configuration of the display according to the first embodiment. In Example 1, as shown in FIG. 3, one display is divided into two, the upper part is driven as the display only, and the lower part activates the optical sensor together with the display.

  Specifically, a configuration is adopted in which gate 1 to gate X are driven as a “display mode” only for the display, and gate X + 1 and later are driven as a “display & sensor output mode” that activates the optical sensor together with the display. Yes.

  The division shown in FIG. 3 is merely an example, and a configuration in which a part of the gate line group in the entire screen is driven as the “display & sensor output mode” is also possible.

  FIG. 4 is a diagram showing drive waveforms in each part of the display shown in FIG. 3 in the first embodiment. The gates 1 to X are driven in the “display mode”. On the other hand, after the gate X + 1, the sensor output is started by the activation of the readout control signal (Vrocont) together with the sensor output start signal (Vsst).

[Example 2]
In the second embodiment, a specific example in which the photosensor pixel circuit shown in the first embodiment is further applied will be described. FIG. 5 is a pixel configuration diagram of the photosensor pixel circuit according to the second embodiment. As shown in FIG. 5, in the second embodiment, each pixel is configured in an RGBW configuration. In the area of the gate line that is driven as the “display & sensor output mode”, the white pixel is replaced with a sensor pixel.

  In this way, by using the White pixel, it is possible to realize a configuration in which the optical sensor is built in the display surface, and to obtain the above-described features 1 and 2.

[Example 3]
In this third embodiment, a specific example of sensor output wiring in the photosensor pixel circuit shown in the first embodiment will be described. FIG. 6 is a cross-sectional view illustrating the arrangement of the sensor output wiring of the photosensor pixel circuit according to the third embodiment. In the example of FIG. 6, wirings Vrov and Vrol as output lines to be newly added are formed in the same layer as the dielectric III layer.

  As described above, according to the first embodiment, the use of the gate line for the control (reset and readout) of the optical sensor eliminates the need for a special driving IC. Furthermore, a new additional wiring is not required for the control line, and a transparent wiring is used for the output line, thereby preventing the aperture ratio from being lowered.

  By adopting such a configuration, it is possible to incorporate an optical sensor on the display surface, and it is possible to reduce costs by reducing the number of parts and provide new functions to customers. As a result, it is possible to obtain a photosensor pixel circuit for a display device and a display device that can realize simplification of control and suppression of reduction in aperture ratio.

  Note that a PIN diode, an amorphous diode, an n-type diode, or the like can be used as a photodiode that is an optical sensor.

  M1 Thin film transistor, PD photodiode, Vrov, Vrol A pair of wirings (output lines), Gate (n), Gate (n + 1) Gate lines (control lines).

Claims (7)

An optical sensor pixel circuit for a display device in which an optical sensor is built in at least a part of a display surface,
In each of the n-th line photosensor pixels in which the photosensor is incorporated,
As a control line of the photosensor, a gate line (n + 1) is used as a reset signal, a gate line (n) is used as a readout signal,
As the output line of the photosensor, a pair of wirings different from the data line is newly formed with a transparent electrode, and the detection signal from the photosensor is output .
Each of the photosensor pixels
One photodiode having a cathode connected to the gate line (n) and an anode connected to the gate line (n + 1) and performing light amount detection;
A gate is connected to the gate line (n), a source and a drain are connected between the pair of wirings, and the read signal is input to the gate via the gate line (n). One thin film transistor for outputting a detection signal from the photodiode;
An optical sensor pixel circuit for a display device comprising: The output line is in a floating state with no potential fixed except when the photosensor is activated, and when activated, one of the pair of wirings supplies a high potential and the other is The photosensor pixel circuit for a display device according to claim 1, which plays a role of outputting the detection signal. Each of the photosensor pixels
Said anode and said gate of said thin film transistor, one photosensor pixel circuit for a display device according to claim 1 or 2 is connected to the gate line (n) through capacitor of the photodiode. The photosensor pixel circuit for a display device according to claim 1, wherein the photodiode is any one of a PIN diode, an amorphous diode, and an n-type diode. Each of the optical sensor pixel, when one pixel for display is composed of four pixels of RGBW, the display according to claims 1, which consists of replacing the W pixel in any one of 4 Photosensor pixel circuit for the device. The photosensor pixel circuit for a display device according to any one of claims 1 to 5 , wherein each of the photosensor pixels is formed in a part of a gate line group in the entire screen. The display apparatus containing the photo sensor pixel circuit for display apparatuses of any one of Claim 1 to 6 .

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