Thin film transistor photosensitive circuit, display panel and mobile device using the same

Abstract

The present invention provides a thin film transistor photosensitive circuit, a display panel and a mobile device using the same. The thin film transistor photosensitive circuit includes N×M photosensitive units, M reading circuits and a control circuit. Each photosensitive unit includes a photosensitive circuit and a switch circuit. The photosensitive part of the photosensitive circuit is composed of a gap-type thin film transistor. Since the photosensitive circuit is made of a gap-type thin film transistor, the time required for photosensitivity is much shorter than that of a photodiode. In the present invention, there is no need to give special integration time. As long as the control circuit turns on the photosensitive circuit for photosensitivity, the photosensitivity results can be directly read by the M reading circuits. Therefore, photosensitivity and scanning reading can be performed simultaneously.

Description

Technical Field

[0001] The present invention relates to a biometric identification technology, in particular to a biometric identification technology using a thin film transistor photosensitive circuit, a display panel and a mobile device using the same. Background Art

[0002] Fingerprint recognition technology is a biometric technology. The fingerprint recognition system is an image recognition system that includes modules such as fingerprint image acquisition, processing, feature extraction and comparison. It is often used in places where personnel identity confirmation is required, such as access control systems, attendance systems, notebook computers, mobile devices, internal bank processing and bank payments. Currently, optical fingerprint recognition used in mobile devices is divided into button type and under-screen type. Button-type fingerprint recognition devices are generally configured on the power button or HOME button of the mobile device, while under-screen fingerprint recognition devices are generally configured in a specific position under the organic light-emitting diode panel. However, if the user's finger is not in a specific position, the above-mentioned under-screen fingerprint recognition device cannot recognize the user's fingerprint.

[0003] In addition, the under-screen fingerprint recognition device requires an image capture device. Generally, the image capture device mainly uses a pixel sensor array, which includes a passive pixel sensor (PPS) and an active pixel sensor (APS). The main difference between the two pixel sensor arrays is that the circuit of the passive pixel sensor is a selection switch composed of a single transistor. Among them, when light excites the electrons of the above transistor, the electrons will be stored in the capacitor, and then the amplifier at the end of each column will read the electrical signal accumulated by the pixels at the intersection of the rows and columns, and then amplify the electrical signal. The advantage of the passive pixel sensor is that the circuit is simple and will not affect the sensitivity of the sensor because it occupies too much light-sensitive area. The disadvantage is that the output line impedance of the signal is extremely high, which is easy to generate random noise and cause poor image quality.

[0004] The circuit of the active pixel sensor is an amplifier formed by coupling transistors to each pixel. In addition, the design of the active pixel sensor solves the problem that passive pixel sensors are prone to random noise. However, since the amplifier circuit occupies too much of the photosensitive area of ​​the pixel, the number of pixels that can be placed per unit area of ​​the sensor is reduced, and the resolution is also reduced. In addition, it is not easy to make the amplifier characteristics on each pixel consistent, resulting in some pixels having a larger voltage and some pixels having a smaller voltage. After the process is completed, these amplifier characteristics cannot be changed. Therefore, the so-called fixed pattern noise will be generated, making the captured image like the scenery seen through a dirty window. Therefore, the sensors used in most products are still mainly passive pixel sensors.

[0005] Figure 1 The circuit diagram of the image capture device of the conventional optical fingerprint recognition device is shown. Figure 1 In this embodiment, the image capture device includes N×M image capture units and M readout circuits 110. Each image capture unit includes a switch M1, an energy storage element 101, and a photodiode 102. Generally speaking, the photodiode 102 adopts a PIN diode structure, and PIN refers to P-type doping, an intrinsic layer, and N-type doping. That is, an intrinsic layer is additionally configured between the P-type doping and the N-type doping. Figure 2 The figure shows the operation diagram of the image capture device of the conventional optical fingerprint recognition device. Figure 2 In this example, each row requires a long integration time to allow the energy storage element 101 in the image capture unit to accumulate charge. After the integration time is over, the reading circuit 110 can read and reset. However, this type of optical fingerprint recognition device has a too long integration time and requires a very high-intensity light source. For under-screen fingerprint recognition, it often results in an insufficient signal-to-noise ratio (SNR), making the fingerprint unclear or even unrecognizable. In addition, if the signal-to-noise ratio needs to be increased, it will take longer to read the fingerprint, which is a big defect for the product. Summary of the invention

[0006] An object of the present invention is to provide a thin film transistor photosensitive circuit, a display panel and a mobile device using the same, so as to adopt a thin film transistor process to manufacture a photosensitive circuit with a fast photosensitive speed, so as to achieve fast image capture and be suitable for optical fingerprint recognition under the panel.

[0007] To this end, the present invention provides a thin film transistor photosensitive circuit, which is configured on a glass substrate. The thin film transistor photosensitive circuit includes N×M photosensitive units, M reading circuits and a control circuit. Each photosensitive unit includes a photosensitive circuit and a switch circuit. The photosensitive part of the photosensitive circuit is composed of a gap-type thin film transistor, including a control end, a first end and a second end, wherein the first end of the photosensitive circuit is coupled to a first power supply end. The switch circuit includes a first end, a second end and a control end, wherein the first end of the switch circuit is coupled to the second end of the photosensitive circuit. Each reading circuit includes an input end and an output end, and the input end of the Kth reading circuit is coupled to the second end of the N switch circuits in the Kth row. The control circuit includes N scanning ends, and the Kth scanning end is coupled to the control ends of the M photosensitive circuits in the Kth row and the control ends of the M switch circuits. The control circuit sequentially scans the M photosensitive units in the first to Nth rows through the N scanning terminals to sequentially read out the M photosensitive signals in each row. When the Kth scanning terminal is enabled, the M photosensitive circuits and M switch circuits in the Kth row are turned on simultaneously.

[0008] The present invention further provides a display panel, which includes a fingerprint recognition device disposed under the display panel. The fingerprint recognition device includes a thin film transistor photosensitive circuit, which is disposed on a glass substrate. The thin film transistor photosensitive circuit is as described above.

[0009] The present invention further provides a mobile device, which includes a display panel and a fingerprint recognition device. The fingerprint recognition device is disposed under the display panel and includes a thin film transistor photosensitive circuit, which is disposed on a glass substrate and is as described above.

[0010] According to the thin film transistor photosensitive circuit, display panel and mobile device using the same described in the preferred embodiment of the present invention, the above-mentioned photosensitive circuit includes a gap-type thin film transistor, including a gate, a first source and drain and a second source and drain, wherein the gate of the gap-type thin film transistor is coupled to the control end of the photosensitive circuit, the first source and drain of the gap-type thin film transistor is coupled to the first end of the photosensitive circuit, and the second source and drain of the gap-type thin film transistor is coupled to the second end of the photosensitive circuit, wherein the amorphous silicon channel of the gap-type thin film transistor only covers a portion of the gate.

[0011] According to the thin film transistor photosensitive circuit, display panel and mobile device using the same described in the preferred embodiment of the present invention, the gap length from the gate to the second source and drain of the above-mentioned gap-type thin film transistor is between 2 μm and 10 μm.

[0012] According to the thin film transistor photosensitive circuit, display panel and mobile device using the same described in the preferred embodiment of the present invention, the reading circuit includes a resistor circuit and an analog-to-digital converter. The input end of the resistor circuit of the Kth reading circuit is coupled to the second end of the switch circuit of the Kth row. The input end of the analog-to-digital converter is coupled to the output end of the resistor circuit, wherein the output end of the analog-to-digital converter of the Kth reading circuit outputs the photosensitive data of the enabled Kth photosensitive unit.

[0013] According to the thin film transistor photosensitive circuit, display panel and mobile device using the same described in the preferred embodiment of the present invention, each of the above-mentioned reading circuits also includes a controllable current source, including an input end, wherein the input end of the Kth controllable current source is coupled to the second end of the Kth row of switching circuits, and the current of the controllable current source can be adjusted according to the ambient light intensity.

[0014] According to the thin film transistor photosensitive circuit, display panel and mobile device using the same described in the preferred embodiment of the present invention, the controllable current source includes a first transistor, a second transistor, an impedance element and a digital-to-analog converter. The first source and drain of the first transistor are coupled to a power supply voltage, the gate of the first transistor is coupled to the second source and drain of the first transistor, and the second source and drain of the first transistor are coupled to the input end of the controllable current source. The first source and drain of the second transistor are coupled to a power supply voltage, and the gate of the second transistor is coupled to the gate of the first transistor. The first end of the impedance element is coupled to the second source and drain of the second transistor, and the second end of the impedance element is coupled to a common voltage. The output end of the digital-to-analog converter is coupled to the second source and drain of the second transistor. According to the intensity of ambient light, the data of the digital-to-analog converter is adjusted to control the current of the first transistor.

[0015] The spirit of the present invention is to use gap-type thin film transistors as photosensitive circuits, and to manufacture gap-type thin film transistor photosensitive circuits on glass substrates using panel manufacturing processes. In addition to having a very large cost advantage, the size can also be made larger than that of silicon-based semiconductors. And the photosensitive effect is much greater than that of photodiodes. Therefore, there is no need to use a capacitor integration method, and the photosensitive results can be directly read. Even when the carrier mobility of the thin film transistor is much smaller than that of the silicon-based semiconductor material, extremely fast photosensitivity can still be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. 1 is a circuit diagram of an image capture device of an optical fingerprint recognition device in the prior art.

[0017] Figure 2 FIG. 1 is a schematic diagram showing the operation of an image capture device of an optical fingerprint recognition device in the prior art.

[0018] Figure 3 FIG. 1 is a schematic diagram of a mobile device according to a preferred embodiment of the present invention.

[0019] Figure 4 FIG. 1 is a circuit block diagram of a thin film transistor photosensitive circuit 301 according to a preferred embodiment of the present invention.

[0020] Figure 5 FIG. 1 is a schematic structural diagram of a gap-type thin film transistor according to a preferred embodiment of the present invention.

[0021] Figure 6 FIG. 1 is a schematic diagram showing the structure of a thin film transistor in the prior art.

[0022] Figure 7 Shown is a circuit diagram of a thin film transistor photosensitive circuit according to a preferred embodiment of the present invention.

[0023] Figure 8 Shown is a circuit diagram of a thin film transistor photosensitive circuit according to a preferred embodiment of the present invention.

[0024] Fig. 9 FIG. 8 is a circuit diagram of a controllable current source 801 according to a preferred embodiment of the present invention.

[0025] Fig.10 FIG. 1 is a schematic structural diagram of a gap-type thin film transistor according to a preferred embodiment of the present invention.

[0026] In the figure, M1: switch

[0027] 101: Energy storage components

[0028] 102: Photodiode

[0029] 110: Reading circuit

[0030] 300: Display panel with optical reading function

[0031] 301: Thin-film transistor photosensitive circuit disposed under the display panel 300

[0032] 401: N×M photosensitive units

[0033] 402: M reading circuits

[0034] 403: Control circuit

[0035] 501: Gate Metal

[0036] 502: Gate oxide layer

[0037] 503: Channel

[0038] 504: Doped amorphous silicon

[0039] 505: Source and drain metal

[0040] 60: Photosensitive unit

[0041] 61: Reading Circuit

[0042] 62: Control circuit

[0043] 601: Photosensitive circuit

[0044] 602: Switching Circuit

[0045] MG: Gap-type thin film transistor

[0046] M2: Thin Film Transistor

[0047] 611: Resistor Circuit

[0048] 612: Analog-to-digital converter

[0049] 711: Integrator

[0050] 801: Controllable current source

[0051] 901: The first transistor

[0052] 902: Second transistor

[0053] 903: Impedance element

[0054] 904: Digital to Analog Converter

[0055] VDD: power supply voltage

[0056] 1001, 1002: Gate metal DETAILED DESCRIPTION

[0057] Figure 3 The figure shows a schematic diagram of a mobile device according to a preferred embodiment of the present invention. Figure 3 The mobile device includes a display panel 300 with an optical reading function and a thin film transistor photosensitive circuit 301 disposed under the display panel 300. Generally speaking, the most common application of the optical reading function under the panel is fingerprint recognition, and fingerprint recognition is used as an example below. The display panel 300 is, for example, an organic light emitting diode panel. However, the present invention is not limited thereto.

[0058] Figure 4 The circuit block diagram of the thin film transistor photosensitive circuit 301 of a preferred embodiment of the present invention is shown. Figure 4The thin film transistor photosensitive circuit 301 includes N×M photosensitive units 401, M reading circuits 402 and a control circuit 403. The photosensitive unit 401 is disposed under the display panel, and is composed of, for example, a thin film transistor and a gap-type thin film transistor. The photosensitive unit 401 is manufactured on a glass substrate using a panel manufacturing process.

[0059] Figure 5 The figure shows the structure of a gap-type thin film transistor according to a preferred embodiment of the present invention. Figure 5 , 501 is the gate metal; 502 is the gate oxide layer; 503 is the channel, which is generally made of amorphous silicon; 504 is doped amorphous silicon; 505 is the source and drain metal. Figure 5 It can be seen that the above-mentioned gap-type thin film transistor has an asymmetric structure and exposes a very large part of the thin film transistor channel to receive light. In the diagram of the gap-type thin film transistor of this embodiment, the non-overlapping channel portion Li is marked. In this way, the gap-type thin film transistor can have different conduction conditions according to the different light received, thereby determining the brightness of the received light. However, in the thin film transistor of the prior art, the channel and the gate electrode completely overlap, such as Figure 6 By comparison Figure 5 and Figure 6 It can be seen that the channel LTFT and the gate of a general thin film transistor completely overlap and can be a symmetrical structure.

[0060] Figure 7 The circuit diagram of a thin film transistor photosensitive circuit of a preferred embodiment of the present invention is shown. Figure 7 In this embodiment, in order to facilitate the explanation of the spirit of the present invention, only 2×2 photosensitive units are drawn. However, those with ordinary knowledge in the relevant technical field should know that the number and configuration of photosensitive units can be expanded according to different designs, so the present invention is not limited to this. This thin film transistor photosensitive circuit includes a plurality of photosensitive units 60, a plurality of reading circuits 61 and a control circuit 62. Each photosensitive unit 60 includes a photosensitive circuit 601 and a switch circuit 602. The photosensitive circuit 601 in this embodiment is, for example, composed of a single gap-type thin film transistor MG. Figure 7 The diagram of FIG. 60 is represented by half of a gate electrode. The switch circuit 602 is implemented by, for example, a common thin film transistor M2. The read circuit 61 is implemented by, for example, a resistor circuit 611 and an analog-to-digital converter 612.

[0061] In this embodiment, the control ends of the photosensitive circuit 601 and the switch circuit 602 are coupled to the control circuit 62, and the control circuit 62 performs light sensing in a scanning manner, for example, that is, in the first scanning time, the control circuit 62 controls the scanning line G0 to be enabled, and reads out the data DAT_1 and DAT_2 through the reading circuit 61. Then, in the second scanning time, the control circuit 62 controls the scanning line G1 to be enabled, and reads out the data DAT_1 and DAT_2 through the reading circuit 61... and so on. However, more particularly, in this embodiment, a source and drain of the gap-type thin film transistor MG of the photosensitive circuit 601 is not coupled to the energy storage element, but is coupled to the switch circuit 602, and the other source and drain of the gap-type thin film transistor MG is coupled to the power supply terminal. Since in this embodiment, the photocurrent of the gap-type thin film transistor MG is more than a thousand times greater than the photocurrent of the photodiode in the prior art, in this embodiment, the reading circuit 61 only uses a simple resistor circuit 611 and an analog-to-digital converter 612 structure, and does not use an integrator as in the prior art. The reason is that the photocurrent of the photosensitive circuit 601 in the embodiment of the present invention is large enough to use a resistor to directly read the voltage after exposure, and the required accumulation (integration) time can also be greatly reduced. Therefore, in this embodiment, the gate of each row will be turned on in sequence, and the signal value can be read at the same time. Therefore, the reading speed advantage of the thin film transistor photosensitive circuit in the embodiment of the present invention is more obvious. Although the simple resistor circuit 611 is used as an example of the present invention in the above embodiment, those with ordinary knowledge in the relevant technical field should know that the present invention can also use an integrator as the reading circuit 61, so the present invention is not limited to this.

[0062] In the above embodiment, the thin film transistor photosensitive circuit 601 can be made on a glass substrate. If a semiconductor process is used to make a large-area optical fingerprint recognition circuit, the price will be very expensive. However, in the present embodiment, the glass substrate and thin film transistor process are used, which has great cost advantages. In addition, compared with the photodiodes used in the prior art, if the photodiodes are also made using a glass substrate and a thin film transistor process, many additional masks will be required, and the same number of masks as the original liquid crystal display panel cannot be used. The general thin film transistors and gap-type thin film transistors used in the present invention can completely use the original panel process in terms of process.

[0063] Figure 8 The circuit diagram of a thin film transistor photosensitive circuit of a preferred embodiment of the present invention is shown. Figure 6 as well as Figure 8Similarly, in order to facilitate the explanation of the spirit of the present invention, only 2×2 photosensitive units are drawn. In this embodiment, a controllable current source 801 is additionally coupled to each column of the switch circuit 602. For the sake of clarity, the node Z is marked. This controllable current source 801 adjusts the current size according to the brightness of the ambient light. For example, since the gap-type thin-film transistor MG of the embodiment of the present invention is extremely sensitive to light, if the ambient light is strong, it is likely to be saturated instantly, resulting in the inability to identify the fingerprint. Therefore, in this embodiment, a controllable current source 801 adjusted according to the ambient light is used. The controllable current source 801 is used to adjust the current to perform fingerprint calibration.

[0064] Fig. 9 The circuit diagram of a controllable current source 801 according to a preferred embodiment of the present invention is shown. Fig. 9 In this embodiment, the controllable current source includes a first transistor 901, a second transistor 902, an impedance element 903 and a digital-to-analog converter 904. In this embodiment, the first source and drain of the first transistor 901 are coupled to the power supply voltage VDD, and the second source and drain of the first transistor 901 are coupled to the node Z and the gate of the first transistor 901. The gate of the first transistor 901 is coupled to the gate of the second transistor 902. The first source and drain of the second transistor 902 are coupled to the power supply voltage VDD, and the second source and drain of the second transistor 902 are coupled to the impedance element 903 and the output end of the digital-to-analog converter 904. In this embodiment, the magnitude of the current of the first transistor 901 is controlled by the digital-to-analog converter 904. The digital-to-analog converter 904 changes the analog voltage outputted by it according to the data of the brightness of the ambient light. In this way, the fingerprint can be calibrated according to the intensity of the ambient light.

[0065] Fig.10 The structure diagram of the gap-type thin film transistor of a preferred embodiment of the present invention is shown. Figure 5 and Fig.10 , it can be seen that Fig.10 There are two gate metals 1001 and 1002. Similarly, the channel and the two gate electrodes 1001 and 1002 only overlap partially. Figure 5 The present invention is limited to the embodiments of the present invention.

[0066] Table 1 shows the gap lengths of the gap-type thin film transistors of the embodiments of the present invention. Figure 5Li in the table is a comparison of the photocurrent size. In the following Table 1, tests were performed with 2um, 6um and 10um respectively, and the test conditions were set at a drain voltage VD and a gate voltage VG equal to 20V and 21 tests were performed, each with an interval of 30 seconds. It can be seen from the following Table 1 that the photocurrent of the gap-type thin film transistor with a gap of 2um is 8.689uA, the photocurrent of the gap-type thin film transistor with a gap of 6um is 3.446nA, and the photocurrent of the gap-type thin film transistor with a gap of 10um is 0.805nA. In addition, the gap-type thin film transistor with a gap of 2um also performs better. However, gap-type thin film transistors with a gap of 2 to 10um are all within the application range of the embodiments of the present invention. That is to say, the gap length Li of the gap-type thin film transistor of the embodiment can also be defined from the edge of the gate side to the edge of the source and drain or the non-overlapping channel portion, which can be between 2 and 10um.

[0067]

[0068] Table 1

[0069] In summary, the spirit of the present invention is to use gap-type thin film transistors as photosensitive circuits, and to manufacture gap-type thin film transistor photosensitive circuits on glass substrates using panel manufacturing processes. In addition to having a very large cost advantage, the actual manufacturing size can also be larger than that of silicon-based semiconductors. And the photosensitive effect is much greater than that of photodiodes. Therefore, there is no need to use a capacitor integration method, and the photosensitive results can be directly read. Even when the carrier mobility of the thin film transistor is much smaller than that of the silicon-based semiconductor material, extremely fast photosensitivity can still be achieved.

[0070] The specific embodiments proposed in the detailed description of the preferred embodiments are only used to facilitate the description of the technical content of the present invention, and are not intended to narrowly limit the present invention to the above embodiments. Various changes and implementations made without exceeding the spirit of the present invention and the following claims are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the definition of the attached claims.

Claims

1. A thin film transistor photosensitive circuit, disposed on a glass substrate, characterized in that: The thin film transistor photosensitive circuit includes: N×M photosensitive units, each of which comprises: A photosensitive circuit, the photosensitive part of which is composed of a gap-type thin film transistor, including a control terminal, a first terminal and a second terminal, wherein the first terminal of the photosensitive circuit is coupled to a first power terminal; and A switch circuit comprises a first terminal, a second terminal and a control terminal, wherein the first terminal of the switch circuit is coupled to the second terminal of the photosensitive circuit; M readout circuits, each of the readout circuits comprising an input terminal and an output terminal, the input terminal of the Kth readout circuit being coupled to the second terminals of the N switch circuits in the Kth row; and A control circuit includes N scanning terminals, wherein the Kth scanning terminal is coupled to the control terminals of the M photosensitive circuits in the Kth row and the control terminals of the M switch circuits; The control circuit sequentially scans the M photosensitive units in the first row to the Nth row through the N scanning ends to sequentially read out the M photosensitive signals of each row. When the Kth scanning end is enabled, the M photosensitive circuits and the M switch circuits in the Kth row are turned on at the same time.

2. The thin film transistor photosensitive circuit according to claim 1, characterized in that: The photosensitive circuit includes: A gap-type thin film transistor comprises a gate, a first source-drain and a second source-drain, wherein the gate of the gap-type thin film transistor is coupled to the control end of the photosensitive circuit, the first source-drain of the gap-type thin film transistor is coupled to the first end of the photosensitive circuit, and the second source-drain of the gap-type thin film transistor is coupled to the second end of the photosensitive circuit. The amorphous silicon channel of the gap-type thin film transistor only covers a portion of the gate.

3. The thin film transistor photosensitive circuit according to claim 1, characterized in that: The gap length from the gate to the second source and drain of the gap-type thin film transistor is between 2 μm and 10 μm.

4. The thin film transistor photosensitive circuit according to claim 1, characterized in that: Each of the reading circuits comprises: a resistor circuit, comprising an input terminal and an output terminal, wherein the input terminal of the resistor circuit of the Kth read circuit is coupled to the second terminal of the switch circuit of the Kth row; and An analog-to-digital converter comprises an input terminal and an output terminal, wherein the input terminal of the analog-to-digital converter is coupled to the output terminal of the resistor circuit. The output terminal of the analog-to-digital converter of the Kth reading circuit outputs the light-sensing data of the enabled Kth light-sensing unit.

5. The thin film transistor photosensitive circuit according to claim 4, characterized in that: Each of the reading circuits further comprises: A controllable current source includes an input terminal, wherein the input terminal of the K-th controllable current source is coupled to the second terminal of the switch circuit of the K-th row, Wherein, the current of the controllable current source is adjusted according to the intensity of the ambient light.

6. The thin film transistor photosensitive circuit according to claim 5, characterized in that: The controllable current source comprises: a first transistor, comprising a gate, a first source and a drain, and a second source and a drain, wherein the first source and the drain of the first transistor are coupled to a power supply voltage, the gate of the first transistor is coupled to the second source and the drain of the first transistor, and the second source and the drain of the first transistor are coupled to the input terminal of the controllable current source; a second transistor, comprising a gate, a first source and a drain, and a second source and a drain, wherein the first source and the drain of the second transistor are coupled to a power supply voltage, and the gate of the second transistor is coupled to the gate of the first transistor; an impedance element, comprising a first end and a second end, wherein the first end of the impedance element is coupled to the second source-drain of the second transistor, and the second end of the impedance element is coupled to a common voltage; and a digital-to-analog converter, comprising an output terminal, wherein the output terminal of the digital-to-analog converter is coupled to the second source and drain of the second transistor; Wherein, according to the intensity of the ambient light, the data of the digital-to-analog converter is adjusted to control the current of the first transistor.

7. A display panel, characterized in that: include: A fingerprint recognition device is disposed under the display panel. The fingerprint recognition device includes a thin film transistor photosensitive circuit. The thin film transistor photosensitive circuit is disposed on a glass substrate. The thin film transistor photosensitive circuit includes: N×M photosensitive units, each of which comprises: A photosensitive circuit, the photosensitive part of which is composed of a gap-type thin film transistor, including a control terminal, a first terminal and a second terminal, wherein the first terminal of the photosensitive circuit is coupled to a first power terminal; and A switch circuit comprises a first terminal, a second terminal and a control terminal, wherein the first terminal of the switch circuit is coupled to the second terminal of the photosensitive circuit; M readout circuits, each of the readout circuits comprising an input terminal and an output terminal, the input terminal of the Kth readout circuit being coupled to the second terminals of the N switch circuits in the Kth row; and A control circuit includes N scanning terminals, wherein the Kth scanning terminal is coupled to the control terminals of the M photosensitive circuits in the Kth row and the control terminals of the M switch circuits; The control circuit sequentially scans the M photosensitive units in the first row to the Nth row through the N scanning ends to sequentially read out the M photosensitive signals of each row. When the Kth scanning end is enabled, the M photosensitive circuits and the M switch circuits in the Kth row are turned on at the same time.

8. The display panel according to claim 7, wherein: The photosensitive circuit includes: A gap-type thin film transistor comprises a gate, a first source-drain and a second source-drain, wherein the gate of the gap-type thin film transistor is coupled to the control end of the photosensitive circuit, the first source-drain of the gap-type thin film transistor is coupled to the first end of the photosensitive circuit, and the second source-drain of the gap-type thin film transistor is coupled to the second end of the photosensitive circuit. The amorphous silicon channel of the gap-type thin film transistor only covers a portion of the gate.

9. The display panel according to claim 7, wherein: The gap length from the gate to the second source and drain of the gap-type thin film transistor is between 2 μm and 10 μm.

10. The display panel according to claim 7, wherein: The display panel as claimed in claim 7, wherein each of the readout circuits comprises: a resistor circuit, comprising an input terminal and an output terminal, wherein the input terminal of the resistor circuit of the Kth read circuit is coupled to the second terminal of the switch circuit of the Kth row; and An analog-to-digital converter comprises an input terminal and an output terminal, wherein the input terminal of the analog-to-digital converter is coupled to the output terminal of the resistor circuit. The output terminal of the analog-to-digital converter of the Kth reading circuit outputs the light-sensing data of the enabled Kth light-sensing unit.

11. The display panel according to claim 10, wherein: Each of the reading circuits further comprises: A controllable current source includes an input terminal and an output terminal, wherein the input terminal of the K-th controllable current source is coupled to the second terminal of the switch circuit in the K-th row, Wherein, the current of the controllable current source is adjusted according to the intensity of the ambient light.

12. The display panel according to claim 11, wherein: The controllable current source comprises: a first transistor, comprising a gate, a first source and a drain, and a second source and a drain, wherein the first source and the drain of the first transistor are coupled to a power supply voltage, the gate of the first transistor is coupled to the second source and the drain of the first transistor, and the second source and the drain of the first transistor are coupled to the input terminal of the controllable current source; a second transistor, comprising a gate, a first source and a drain, and a second source and a drain, wherein the first source and the drain of the second transistor are coupled to a power supply voltage, and the gate of the second transistor is coupled to the gate of the first transistor; an impedance element, comprising a first end and a second end, wherein the first end of the impedance element is coupled to the second source-drain of the second transistor, and the second end of the impedance element is coupled to a common voltage; and a digital-to-analog converter, comprising an output terminal, wherein the output terminal of the digital-to-analog converter is coupled to the second source and drain of the second transistor; Wherein, according to the intensity of the ambient light, the data of the digital-to-analog converter is adjusted to control the current of the first transistor.

13. A mobile device, characterized in that: include: a display panel; as well as A fingerprint recognition device is disposed under the display panel. The fingerprint recognition device includes a thin film transistor photosensitive circuit. The thin film transistor photosensitive circuit is disposed on a glass substrate. The thin film transistor photosensitive circuit includes: N×M photosensitive units, each of which comprises: A photosensitive circuit, the photosensitive part of which is composed of a gap-type thin film transistor, including a control terminal, a first terminal and a second terminal, wherein the first terminal of the photosensitive circuit is coupled to a first power terminal; and A switch circuit comprises a first terminal, a second terminal and a control terminal, wherein the first terminal of the switch circuit is coupled to the second terminal of the photosensitive circuit; M readout circuits, each of the readout circuits comprising an input terminal and an output terminal, the input terminal of the Kth readout circuit being coupled to the second terminals of the N switch circuits in the Kth row; and A control circuit includes N scanning terminals, wherein the Kth scanning terminal is coupled to the control terminals of the M photosensitive circuits in the Kth row and the control terminals of the M switch circuits; The control circuit sequentially scans the M photosensitive units in the first row to the Nth row through the N scanning ends to sequentially read out the M photosensitive signals of each row. When the Kth scanning end is enabled, the M photosensitive circuits and the M switch circuits in the Kth row are turned on at the same time.

14. The mobile device according to claim 13, wherein: The photosensitive circuit includes: A gap-type thin film transistor comprises a gate, a first source-drain and a second source-drain, wherein the gate of the gap-type thin film transistor is coupled to the control end of the photosensitive circuit, the first source-drain of the gap-type thin film transistor is coupled to the first end of the photosensitive circuit, and the second source-drain of the gap-type thin film transistor is coupled to the second end of the photosensitive circuit. The amorphous silicon channel of the gap-type thin film transistor only covers a portion of the gate.

15. The mobile device according to claim 13, wherein: The gap length from the gate to the second source and drain of the gap-type thin film transistor is between 2 μm and 10 μm.

16. The mobile device according to claim 13, wherein: Each of the reading circuits comprises: a resistor circuit, comprising an input terminal and an output terminal, wherein the input terminal of the resistor circuit of the Kth read circuit is coupled to the second terminal of the switch circuit of the Kth row; and An analog-to-digital converter comprises an input terminal and an output terminal, wherein the input terminal of the analog-to-digital converter is coupled to the output terminal of the resistor circuit. The output terminal of the analog-to-digital converter of the Kth reading circuit outputs the light-sensing data of the enabled Kth light-sensing unit.

17. The mobile device according to claim 16, wherein: Each of the reading circuits further comprises: A controllable current source includes an input terminal and an output terminal, wherein the input terminal of the K-th controllable current source is coupled to the second terminal of the switch circuit in the K-th row, Wherein, the current of the controllable current source is adjusted according to the intensity of the ambient light.

18. The mobile device according to claim 17, wherein: The controllable current source comprises: a first transistor, comprising a gate, a first source and a drain, and a second source and a drain, wherein the first source and the drain of the first transistor are coupled to a power supply voltage, the gate of the first transistor is coupled to the second source and the drain of the first transistor, and the second source and the drain of the first transistor are coupled to the input terminal of the controllable current source; a second transistor, comprising a gate, a first source and a drain, and a second source and a drain, wherein the first source and the drain of the second transistor are coupled to a power supply voltage, and the gate of the second transistor is coupled to the gate of the first transistor; an impedance element, comprising a first end and a second end, wherein the first end of the impedance element is coupled to the second source-drain of the second transistor, and the second end of the impedance element is coupled to a common voltage; and a digital-to-analog converter, comprising an output terminal, wherein the output terminal of the digital-to-analog converter is coupled to the second source and drain of the second transistor; Wherein, according to the intensity of the ambient light, the data of the digital-to-analog converter is adjusted to control the current of the first transistor.

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