Readout chip, identification module, and identification method of TFT optical fingerprint sensor chip

Abstract

The present invention discloses a readout chip, an identification module, and an identification method of a TFT optical fingerprint sensor chip for reading a fingerprint signal output by the TFT optical fingerprint sensor chip, including an integration module, a signal conversion module, and a control module. Channel multiplexing can be achieved through the cooperation of the signal conversion module and the control module, that is, the channels of two or even more integrators can share a signal conversion channel for analog-to-digital conversion. Based on the structure proposed in this application, the number of channels of the entire readout chip can be effectively reduced, and channel multiplexing can be achieved, thereby effectively reducing the area and power consumption of the chip, and reducing the hardware cost of the circuit to a certain extent. In addition, through the cooperation of the control module and the channel selection unit, continuous selection from any position can also be achieved, that is, no matter where the finger touches the TFT optical fingerprint sensor, it can be identified without being limited to a specific place.

Description

Technical Field

[0001] The present invention relates to the field of fingerprint recognition technology, and in particular to a readout chip, a recognition module, and a recognition method of a TFT optical fingerprint sensor chip. Background Art

[0002] Fingerprint recognition technology is the most widely used of many biometric recognition technologies. Its application fields include smart phones, finance, banks, security, attendance, access control, safes, etc. Fingerprint recognition uses the uneven texture formed on the surface of the finger to identify a person's identity. Among them, optical fingerprint recognition technology is one of the fingerprint acquisition methods. The optical fingerprint chip mainly senses light signals with CMOS image sensors. With the development of fingerprint recognition technology, blind touch recognition or large-area fingerprint recognition is gradually promoted to improve the user's fingerprint recognition experience. As the area of ​​the optical fingerprint sensing area increases, the production cost of the CMOS image sensor in the optical fingerprint sensor increases too much, resulting in certain limitations in the application of large-area optical fingerprint sensing areas. Unlike CMOS image sensors, TFT photosensitive array sensors can provide a better user experience while providing a larger range of fingerprint recognition areas due to the low manufacturing cost of the TFT (Thin Film Transistor) photosensitive devices. At the same time, when realizing large-area fingerprint recognition, the overall production price of the entire recognition module can also be controlled within the acceptable range of the market.

[0003] Since the photoelectric signal generated by TFT photosensitive devices is very weak, and there are also large electrical parasitic effects and dark current signals, and the working state of the device will shift during operation due to factors such as process, voltage, temperature and time, it is difficult to integrate complex signal readout and processing circuits. Because the electrical stability of TFT devices is poor and it is difficult to implement complex circuit structures, the main part of the signal readout chip is usually implemented outside the TFT using semiconductor technology to process the signal output by the TFT optical fingerprint sensor chip. Summary of the invention

[0004] The purpose of the present invention is to provide a readout chip, an identification module, and an identification method of a TFT optical fingerprint sensor chip, so as to provide a large-array under-screen optical fingerprint identification module with low manufacturing cost.

[0005] In order to achieve the above object, the present invention proposes an optical fingerprint recognition module including a TFT optical fingerprint sensor chip and a readout chip. The readout chip is used to read the fingerprint signal output by the TFT optical fingerprint sensor chip. The readout chip includes:

[0006] An integration module, comprising a plurality of integrators, wherein the integration module is configured to be electrically connected to an output pad in the TFT optical fingerprint sensor chip to receive a signal output by the TFT optical fingerprint sensor chip;

[0007] The signal conversion module comprises a signal conversion channel unit and a channel selection unit, wherein the signal conversion channel unit comprises a plurality of mutually independent signal conversion channels, and when the signal conversion channel unit is working, the plurality of signal conversion channels are connected to some integrators in the integration module in a one-to-one correspondence; the channel selection unit is used to connect to the signal conversion channel unit and connect the plurality of signal conversion channels to a plurality of integrators specified in the integration module;

[0008] The control module is used to connect with the channel selection unit and control the positions of several integrators specified in the channel selection unit in the integration module.

[0009] Optionally, the specified plurality of integrators are located at consecutive positions in the integration module.

[0010] Optionally, the number of the designated plurality of integrators is 100-150.

[0011] Optionally, a plurality of integrators in the integration module are connected to output pads in the TFT optical fingerprint sensor chip in a one-to-one correspondence.

[0012] Optionally, the number of the signal conversion channels in the signal conversion channel unit is less than the number of the integrators in the integration module;

[0013] The channel selection unit is arranged between the signal conversion channel unit and the integration module.

[0014] Optionally, the channel selection unit includes a decoder and a plurality of control switches;

[0015] The integration module is connected to the designated signal conversion channel unit through the control switch, wherein the designated integrators in the integration module are connected to the signal conversion channels in the signal conversion channel unit in a one-to-one correspondence;

[0016] The decoder is connected to the plurality of control switches to control the designated integrator to connect to the corresponding signal conversion channel;

[0017] The control module is connected to the decoder and outputs information of a designated integrator and a corresponding signal conversion channel to the decoder.

[0018] Optionally, the control switch is a two-or-one selector.

[0019] Optionally, the signal conversion channel unit includes an analog-to-digital converter.

[0020] Based on the same inventive concept, the present invention also proposes a TFT optical fingerprint recognition module, which is applied to an electronic device, wherein the electronic device has a host, the TFT optical fingerprint recognition module communicates with the host, the electronic device has a TFT optical fingerprint recognition area, and the TFT optical fingerprint recognition module includes:

[0021] A touch detection board, used to communicate with the host and detect the position of the finger in the TFT optical fingerprint recognition area;

[0022] TFT optical fingerprint sensor chip, with TFT photosensitive pixels distributed in an array, receiving light signals carrying fingerprints; and

[0023] A readout chip, the readout chip is connected to the TFT optical fingerprint sensor chip and communicates with the host;

[0024] Among them, the area of ​​the readout chip is smaller than the area of ​​the TFT optical fingerprint sensor chip, and the number of channels in the signal conversion module in the readout chip is less than the number of pixels in each row of the TFT optical fingerprint sensor chip; when the readout chip is working, the signal conversion module converts the signals output by a specified number of continuously arranged integrators in the integration module.

[0025] Based on the same inventive concept, the present invention also proposes a TFT optical fingerprint recognition method, which is applied to electronic devices. The recognition method includes:

[0026] Setting an optical fingerprint recognition area on the touch screen of the electronic device;

[0027] Using a touch detection panel to detect the position of a finger in the optical fingerprint recognition area and transmit it to a host in the electronic device;

[0028] The host transmits a control signal to the control module in the TFT optical fingerprint recognition module according to the finger position detected by the touch detection board;

[0029] The control module controls the signal conversion module of the TFT optical fingerprint recognition module to convert the photosensitive signal of the photosensitive pixel array corresponding to the finger position;

[0030] Among them, the area of ​​the photosensitive pixel array is set to be at least larger than the contact area between the two fingers and the optical fingerprint recognition area, and the number of signal conversion channels of the signal conversion channel unit in the readout chip in the TFT optical fingerprint recognition module is less than the number of photosensitive pixels in a single row of the photosensitive pixel array; the control module controls the signal conversion module to convert the photosensitive pixels corresponding to the number of signal conversion channels less than or equal to the number of signal conversion channels included in the signal conversion module to collect finger fingerprints.

[0031] Optionally, the touch screen of the electronic device is a self-luminous screen, the optical fingerprint recognition area is arranged on the self-luminous screen, and the luminous pixels in the self-luminous screen are used to illuminate the target finger in the optical fingerprint recognition area.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The readout chip of the TFT optical fingerprint sensor chip proposed in the present invention can realize channel multiplexing to read the signal of the TFT optical fingerprint sensor chip, thereby reducing the chip area and reducing the cost of the entire optical module. In addition, through the cooperation of the control module and the channel selection unit, it is possible to realize fast and accurate recognition of any position of the finger in a large-area TFT optical fingerprint sensor.

[0034] 2. If the control switch in the channel selection unit is selected as a two-choice selector, the fingerprint recognition of different fingers can be quickly switched.

[0035] The TFT optical fingerprint recognition module and the TFT optical fingerprint recognition method proposed in the present invention belong to the same inventive concept as the readout chip of the TFT optical fingerprint sensor chip, and therefore have the same beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of a TFT optical fingerprint sensor;

[0037] Figure 2 A schematic diagram of a readout chip of a TFT optical fingerprint sensor chip proposed in an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of a readout chip of the TFT optical fingerprint sensor chip proposed in Example 1;

[0039] Figure 4 is a schematic diagram of the control circuit of the decoder;

[0040] Figure 5 This is a schematic diagram of decoder logic signals;

[0041] Figure 6 This is a schematic diagram of a dual-finger TFT optical fingerprint application;

[0042] Figure 7 A schematic diagram of a readout chip of a TFT optical fingerprint sensor chip proposed in Embodiment 2;

[0043] Figure 8 This is a specific example diagram of a readout chip proposed in Embodiment 2;

[0044] Fig. 9 A schematic diagram of the structure of a TFT optical fingerprint recognition module provided in Example 3;

[0045] Fig.10 This is a schematic diagram of the process of the TFT optical fingerprint recognition method proposed in Example 4;

[0046] Among them, 1-electronic device, 2-host, 3-touch detection board, 4-readout chip, 5-gate driver chip, 6-TFT optical fingerprint sensor chip, 10-integrator, 20-control module, 30-channel selection unit, 301-decoder, 302-control switch, 40-signal conversion channel unit. DETAILED DESCRIPTION

[0047] The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer based on the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0048] In the description of the present invention, it is necessary to understand that the terms "center", "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0050] In order to facilitate the understanding of the technical solution of this application, the relevant technologies involved in this application are first explained. Please refer to Figure 1 , Figure 1This is a schematic diagram of a TFT optical fingerprint recognition module. Due to the limitations of the TFT process, the readout chip cannot be built into the pixel unit, and an external readout chip is required to collect information. Figure 1 In the schematic diagram shown in , the TFT optical fingerprint recognition module mainly includes: N rows x M TFT optical fingerprint sensor chips (TFT Sensor), gate driver chips (Gate IC), readout chips (ROIC), and host (Host). The pixel units of the TFT optical fingerprint sensor chip are arranged in N rows x M columns. The gate driver chip is used to provide gate drive signals for TFT transistors in the pixel array of the TFT optical fingerprint sensor chip. When a finger is placed on the fingerprint recognition area of ​​an electronic device, the light emitted by the detection light source will irradiate the finger, and the finger will reflect part of the light from the detection light source through the optical path processing component to the photosensitive area on the TFT optical fingerprint sensor chip. The TFT optical fingerprint sensor chip receives the light signal of the detection light source reflected by the finger and converts the light signal into an electrical signal and transmits it to the readout chip. Among them, this TFT optical fingerprint sensor chip is a photosensitive pixel array made using the TFT process. This chip is different from a semiconductor chip made using a silicon substrate. Instead, it uses a glass substrate, and on the glass substrate, a photosensitive pixel array with a relatively simple structure is made using the TFT process.

[0051] Since the CIS (CMOS Image Sensor) chip is made using semiconductor technology, its optical fingerprint detection area is limited. When making a large-array under-screen fingerprint chip, if the optical fingerprint detection area is increased, the CIS chip area will increase. As a result, large-array CIS fingerprint recognition chips are currently difficult to meet market demand due to their high production costs.

[0052] Based on the above reasons, this application proposes a TFT optical fingerprint recognition module. Among them, the TFT optical fingerprint module at least includes: a TFT optical fingerprint sensor chip and a readout chip. The readout chip is used to read the fingerprint signal output by the TFT optical fingerprint sensor chip. Please refer to Figure 2 Shown is a schematic diagram of a readout chip.

[0053] like Figure 2As shown, the readout chip includes an integration module, a signal conversion module and a control module 20. The integration module 10 includes a plurality of integrators, and the integration module 10 is configured to be electrically connected to the output pad in the TFT optical fingerprint sensor chip to receive the signal output by the TFT optical fingerprint sensor chip. The signal conversion module includes a signal conversion channel unit 40 and a channel selection unit 30. The signal conversion channel unit 40 includes a plurality of independent signal conversion channels. When the signal conversion channel unit 40 is working, the plurality of signal conversion channels are connected to some integrators in the integration module 10 in a one-to-one correspondence. The channel selection unit 30 is used to connect to the signal conversion channel unit 40, and connect the plurality of signal conversion channels to the plurality of integrators specified in the integration module 10. The control module 20 is used to connect to the channel selection unit 30, and control the positions of the plurality of integrators specified in the channel selection unit 30 in the integration module 10.

[0054] The control module 20 in the readout chip controls the signal conversion module, and uses a limited number of signal conversion channels to read the signal output by the large-area TFT optical fingerprint sensor chip, thereby realizing flexible fingerprint recognition in a large-area fingerprint recognition area and reducing the manufacturing cost of the entire TFT optical fingerprint recognition module. In some embodiments, based on the size of the photosensitive pixels made by the TFT process in the TFT optical fingerprint sensor chip, if the same number of photosensitive pixels occupied by conventional finger recognition is required to be read at one time, the number of signal conversion channels required is approximately 100 to 150 channels.

[0055] In the embodiment currently exemplified, the integrators included in the integration module correspond one-to-one with all the photosensitive pixels in a single row in the TFT fingerprint sensor chip. The signal conversion channel unit is controlled by the channel selection unit to convert and process the signals of several integrators specified in the integration module 10. Usually, the specified integrators include at least 100 to 150 integrators. However, if in other embodiments, the integrators in the integration module do not have a one-to-one correspondence with the photosensitive pixels in a single row in the photosensitive pixel array, the signal conversion channel unit has at least 100 to 150 signal conversion channels for each single-row fingerprint signal reading to simultaneously convert and process the single-row fingerprint signal output by the photosensitive pixel array. However, with the change or improvement of the TFT process in the TFT optical fingerprint sensor chip, the change of the photosensitive pixels required for single finger identification will also change the number of signal conversion channels required for simultaneous reading of a single row of fingerprint signals. Therefore, when the photosensitive pixel array manufactured by the TFT process in the currently exemplified TFT optical fingerprint sensor chip simultaneously reads a single row of information of the collected fingerprint, the number of signal conversion channels required is roughly between 100 and 150. Based on the reasons described above, the number of signal conversion channels should not be limited to this specific number. This number is only used as an example and explanation based on the current TFT manufacturing process. Based on the working principle of the optical fingerprint recognition module described above, in this large-array TFT optical fingerprint sensor chip, the required number of signal conversion channels can be less than the number of a single row of photosensitive pixels in the TFT photosensitive pixel array in this chip. In the case where the integrator corresponds one-to-one to a single row of photosensitive pixels in the integration module, the number of signal conversion channels in the signal conversion channel unit 40 is less than the number of integrators in the integration module. That is, the number of signal conversion channels is less than the number of a single row of photosensitive pixels in the photosensitive pixel array. The signal conversion channel unit 40 performs corresponding conversion processing on the signal, such as AD conversion. The signal conversion module also includes a channel selection unit. The channel selection unit 30 is arranged between the signal conversion channel unit 40 and the integration module 10.

[0056] The integration module is electrically connected to the output end of the TFT optical fingerprint sensor chip through the input port in the readout chip. The output end of the TFT optical fingerprint sensor chip usually includes a plurality of output pads electrically separated from each other. The input port of the readout chip also includes a plurality of output pads electrically separated from each other. This output pad is connected one-to-one with part of the output pads in the TFT optical fingerprint sensor chip. In the embodiment described herein, the part where the output pads of the TFT optical fingerprint sensor are connected one-to-one with the output pads in the readout chip is to electrically connect the integrator in the readout chip with a single row of photosensitive pixels one-to-one.

[0057] In some embodiments, the channel selection unit 30 can be implemented using a decoder 301 and a plurality of control switches. The integration module is connected to the specified signal conversion channel unit through the control switch. The integrators in the integration module are connected one-to-one with the signal conversion channels in the specified signal conversion channel unit. The decoder is connected to a plurality of control switches to control the specified integrator to be connected to the corresponding signal conversion channel. The control module is connected to the decoder and outputs the information of the specified integrator and the corresponding signal conversion channel to the decoder. Please refer to Figure 2 , Figure 2 The readout chip of the TFT optical fingerprint sensor chip also includes an input port, which is used to receive fingerprint signals input from the outside, and the input port can be a plurality of output pads. The plurality of integrators 10 in the integration module are connected to the output pads in the TFT optical fingerprint sensor chip in a one-to-one correspondence.

[0058] The following is combined with Figure 3 to Figure 9 The following is a further specific embodiment of the readout chip of the TFT optical fingerprint sensor chip of the present application, as well as the TFT optical fingerprint recognition module and the recognition method, to help those skilled in the art understand the technical solution of the patent protection scope requested by the claims of the present application.

[0059] Please refer to Figures 3 to 6 This embodiment provides a readout chip of a TFT optical fingerprint sensor chip. Figure 3 As shown, the readout chip of the TFT optical fingerprint sensor chip includes a plurality of integration modules 10, a control module 20, a plurality of channel selection units 30 and a plurality of signal conversion channels 40. The integration module 10 includes a plurality of integrators. The plurality of integrators are configured to obtain fingerprint information from the TFT optical fingerprint sensor chip and output it to the corresponding signal conversion channel 40.

[0060] Since the photoelectric signal generated by the TFT photosensitive device is very weak, there are also large electrical parasitic effects and dark current signals, and the signal will also generate high-frequency noise during long-distance transmission. To solve this kind of noise problem, please continue to refer to Figure 3 In this embodiment, the signal conversion module includes a signal conversion channel unit and a channel selection unit. The signal conversion channel unit includes a plurality of independent signal conversion channels. Figure 3 As shown, the configuration of each signal conversion channel can be the same or different. Figure 3In the illustrated embodiment, each signal conversion channel is configured substantially the same. The signal conversion channel includes a low-pass filter and a buffer, and an analog-to-digital converter (ADC). The low-pass filter (LPF) is configured to filter the output signal from the integration module 10 to reduce the high-frequency noise generated during the long-distance transmission of the signal. The signal filtered by the low-pass filter is transmitted to the buffer. The buffer plays the role of isolation, reducing leakage, and improving driving ability. The output of the buffer is given to the analog-to-digital converter for analog-to-digital conversion.

[0061] Please continue to refer to Figure 3 , combined with Figure 3 It is described and illustrated that the readout chip processes the electrical signal output by the TFT optical fingerprint sensor chip. The signal output by the pixel in the corresponding TFT photosensitive pixel array is processed by one of the signal conversion channels. A single pixel unit in the TFT photosensitive pixel array outputs an electrical signal through the output pad of the TFT optical fingerprint sensor chip, and receives the electrical signal through the corresponding output pad in the input port of the readout chip. After passing through the integrator, the electrical signal enters the corresponding signal conversion channel through the control switch. The signal entering the signal conversion channel passes through the low-pass filter and buffer in the signal conversion channel and enters the analog-to-digital converter. The analog-to-digital converter converts the analog signal received by the corresponding integrator of this signal conversion channel into a digital signal.

[0062] In this embodiment, the channel selection unit includes a decoder 301 and a control switch 302. The control switch 302 is a two-choice selector. The output end of the selector is connected to the signal conversion channel 40 in a one-to-one correspondence. Figure 6 The specific application of the TFT optical fingerprint recognition module shown in FIG. Figure 6 As shown, if two-finger switching is required, when fingerprint recognition is performed on two different fingers respectively, or when fingerprint recognition is performed on a single finger at any position in the recognition area, the TFT photosensitive pixel array can be divided into two symmetrical parts. The integrator corresponding to a single row of photosensitive pixels can also be divided into two symmetrical parts: a first part integrator and a second part integrator. The corresponding selector as a control switch is connected to the two integrators respectively. The selector receives the signal of the decoder and selectively outputs the output signal of one of the two connected integrators.

[0063] The integrators connected to the two input terminals of each gate are distributed in the first part Block <1> And the second part Block <0> The integration module 10 includes N integrators. <1> The integrator is: INT <0> To INT <n 2-1>; The second part Block <0> Integrator: INT <n 2>To INT <n-1>. N can be set to an even number.

[0064] like Figure 3 In the embodiment shown, the first selector MUX <0> The two input terminals of the first integrator INT are connected separately: <0> and the N / 2th integrator INT <n 2>, are the first integrators in the first and second integrators, respectively. The second selector MUX <1> The two input terminals are connected to the second integrator INT <1> and the N / 2+1th integrator INT<N / 2+1> , respectively, the second integrator in the first and second integrators. The third selector MUX <2> The two input ends of MUX are connected to the first part integrator and the third integrator in the second part integrator. <n 2-1>The two input ends of the gate are connected to the integrator at the end of the first part integrator and the second part integrator respectively. The output end of each gate corresponds to a signal conversion channel.

[0065] Please refer to Figure 4 , Figure 4 for Figure 3 Schematic diagram of an embodiment of the specific internal structure of the decoder. For example, when the enable signal EN of the decoder is 0, the output signal Y <n 2-1:0>= b, 000…0, the selectors connected to the decoder can select channel 0 to open, that is, select Figure 3 The second part of the integrator Block <0> When the decoder enable signal EN=1, if the input signal Dec received by the decoder <a:0>=n, then the decoder output signal Y <n:0>=000…0, and Y<N / 2-1:n> =111…1. For example, when n=3, N=440, the output terminal Y<3:0>=0000, the Block is selected. <0> Integrator INT in <220> ~INT <223> , output terminal Y<219:4>=111…1, select Block <1> Integrator INT in <4> ~INT <219> Thus, the output of the decoder realizes the function of continuously selecting N / 2 integrators starting from any integrator position. It can be understood that the EN is the enable terminal of the decoder. When EN = 0, only Block <0> Module, when EN=1, you can select Block <0> Module, and can select Block <1> module.

[0066] Please refer to Figure 5 , Figure 5 Schematic diagram of decoder logic signal. Taking the decoder output bit number as 8 bits as an example, when n = 0, Y<7:0> = 11111111, and the output of the decoder is all high-level output. When n = 1, the decoder output signal Y<7:0> = 1111110, that is, the lowest bit is 0, and the decoder output Y <0> By analogy, when n=7, DecYb<7:0>=10000000, the decoder output terminal Y <0> ~Y <6> Both are low level, output terminal Y <7> Therefore, the input channel of MUX can be selected by controlling the input of the decoder, thereby realizing channel multiplexing.

[0067] Please refer to Figure 6 , Figure 6 The schematic diagram of the application of the readout chip of the TFT optical fingerprint sensor chip. The TFT photosensitive device can realize the fingerprint signal reading in a large area of ​​the display screen of the electronic device 1. The TFT photosensitive device has a simple process, low price, and is easy to realize large-area manufacturing on a thin film, and can provide a lightweight, cheap, large-area fingerprint signal reading sensor device. The fingerprint areas of the two fingers in the figure correspond to Figure 3 Block <0> and Block <1> When Y <n 2-1:0>=111…1, Block <0> All the integrators in the middle are selected. At this time, the fingerprint signal of the TFT optical fingerprint sensor chip on the right side corresponding to the second part of the integrator is read out. <n 2-1:0>=000…0, Block <0> All the integrators in the middle are selected, and the signal on the left side of the TFT optical fingerprint sensor chip corresponding to the first part of the integrator is read out. Thus, the TFT optical fingerprint sensor signal readout chip has a dual-finger switching mode, which provides convenience for users to flexibly select finger recognition and enhances reliability.

[0068] above Figures 3 to 6 The design of the readout chip in the described embodiment can use fewer signal conversion channels to realize the reading of the signal of the large-array TFT optical fingerprint sensor chip. In this embodiment, it is possible to quickly switch and identify two fingers. At the same time, the fingerprint signal of a single finger can also be read and identified from any position. The signal conversion channels in the signal conversion channel unit work simultaneously to convert the corresponding received fingerprint signals. In this embodiment, for the two-choice gate, the number of signal conversion channels is half the number of pixels in a single row of the TFT optical fingerprint sensor chip.

[0069] Although Figure 3 The connection relationship between the gate and the integrator in the integration module is disclosed as such, but it is not used as a limitation on the scope of patent protection requested by the claims of this application. Figure 4 Only for the corresponding Figure 3 This two-choice selector is a specific embodiment of the internal structure of the decoder, but it is not limited to this. In this embodiment, the control switch selects a two-choice selector, but it does not mean that only this type of selector can be selected. In other embodiments, the control switch 302 can also select other types of selectors, for example, a three-choice selector or a four-choice selector. The specific selection can be based on actual needs and is not limited here. The cooperation of the decoder 301 and the selector can realize channel multiplexing and dual-finger switching, so that the TFT optical fingerprint sensor signal readout chip has a dual-finger switching mode, which provides convenience for users to flexibly select finger recognition and enhances reliability.

[0070] Please refer to Figures 7 to 9 Another design scheme of a readout chip of a TFT optical fingerprint sensor chip is introduced, which can reduce the number of signal conversion channels in a signal conversion channel unit while realizing flexible readout of single-finger fingerprint information on the TFT optical fingerprint sensor chip.

[0071] Please refer to Figure 7 , corresponding to the M-column TFT optical fingerprint sensor chip, the integration module in the readout chip is divided into Q groups. The input port in the readout chip includes at least M output pads, and the M output pads are connected one-to-one with a single row of pixels of the TFT optical fingerprint sensor chip. When the integrator in the integration module is connected one-to-one with the M output pads, the input of each integrator in the Q-group integrator is M / Q. The first integrator group corresponds to IN<0:M / Q-1>, and the second integrator group corresponds to IN <m q:2m q-1>By analogy, we can get the Qth integrator group corresponding to IN <m-m p-1:m-1>. In this embodiment, the division of the integrator module is the same as the division of the M input points. Several signal conversion channels in the signal conversion module are divided into K groups, and the number of signal conversion channels contained in each group is the same as the number of integrators in the integrator group (that is, M / Q channels). In this embodiment, since the structure of the signal conversion channel is substantially the same as that of the signal conversion channel in the above embodiment, the illustration and description will not be repeated. The channel selection unit includes a decoder and a control switch. In this embodiment, the decoder is used to control the opening and closing of the switch. When the decoder outputs a high level, the corresponding switch is turned on, and when the decoder outputs a low level, the corresponding switch is turned off. If the readout chip selects to process the integration module according to the selection of a preset number of integrators in a row, and takes P groups of continuous integrators as a scanning mode, then the corresponding TFT optical fingerprint sensor chip with an M-column TFT photosensitive pixel array, the readout chip has Q-P+1 scanning modes B. When scanning mode B 1 When Y 1 ~Y P The switch 1 of the module is turned on, and the fingerprint signal data in the corresponding output pad group 1, output pad group 2...output pad group P is transmitted to Y 1 ~Y P When scanning mode B 2 When Y 2 ~Y P+1 The control switch branch of the output pad group is turned on, and the fingerprint signal data in the corresponding output pads 2, 3, ..., P+1 is transmitted to Y 2 ~Y P+1 , from which other scanning methods can be deduced.

[0072] Please refer to Figure 8 , Figure 8 The 440 output pads of the readout chip shown in the figure correspond to the 440 columns of photosensitive pixel units in the TFT optical fingerprint sensor chip. The integration module 10 includes a number of integrators, which are divided into eight groups. For example, the output pads of the TFT photosensitive pixel array in the TFT optical fingerprint sensor chip are 440. Correspondingly, the integrators in the integration module are connected to the output pads one by one, and there are also 440 integrators. The integrators are divided into 8 groups, each with 55 integrators.

[0073] In this embodiment, the control switch 302 includes a plurality of control switch control branches. The signal conversion channels in the signal channel conversion unit correspond to eight groups of integrators. The signal conversion channels are divided into four groups. The number of signal conversion channels in each group is equal to the number of integrators in each group of integrators, that is, each group of signal conversion channels has 55 channels. In order to enable the control module to control 165 signal conversion channels in the signal conversion module to convert the signals of 165 pixel units in this embodiment, each group of signal conversion channels is connected to at least 3 groups of integrators in the integration module through the corresponding group of control branches. Please refer to Figure 8 , wherein the signal conversion channel group B and the signal conversion channel group C are connected to 6 groups of integrators through corresponding control switch branches. Correspondingly, the decoder in the channel selection unit can select decoders 3-6. Since the 165 pixel units to be read each time are required to be continuous, the 8 integrator groups are arranged in 3 consecutive groups, and there are only six groups of permutations in total: B1, B2, B3, B4, B5 and B6.

[0074] Please refer to Table 1, which is a table of the correspondence between the signal conversion channel group and the output pad or integrator group. Group A signal conversion channels can be connected to output pad groups 1 to 3. Similarly, the correspondence between other modules can be obtained. These correspondences are from Figure 8 The same can be seen in .

[0075] Table 1

[0076]

[0077] Please refer to Table 2, which is the order combination of data readout. When the scanning mode is B1, Dec_sw = 1, read out output pad 1, output pad 2, and output pad 3, which correspond to signal conversion channel groups A, B, and C respectively. The control switch branch corresponding to group A, the control switch branch corresponding to group B, and the control switch corresponding to group C are closed, and the data Data is obtained. <1> 、Data <2> 、Data <3> When the scanning mode is B2 and Dec_sw=2, output pad 2, output pad 3, and output pad 4 are read out, corresponding to signal conversion channel groups A, B, and C respectively. The control switch branch corresponding to group A, group B, and group C are closed, and data Data is obtained. <2> 、Data <3> 、Data <4> . Other data readout sequence combinations can be deduced in a similar manner.

[0078] Table 2

[0079]

[0080] from Figure 8 In the illustrated embodiment, the decoder in the channel selection unit is a 3-6 decoder, wherein the signal conversion channel group B and the signal conversion channel group C can be selected to connect to 6 groups of output pads. The control switch branch that can connect to 6 groups of output pads includes at least 6 sub-switches, and the signal conversion channel group selects the output pad group to be connected. The signal conversion channel group A and the signal conversion channel group D can be selected to connect to 3 groups of output pads, and correspondingly, the control switch branch can only include 3 sub-switches. The decoder corresponding to the control switch branch of group A and group D can be selected Figure 8 The 3-6 decoder shown in the figure can also be selected from other decoders that only input 3-digit control signals, so that the selective access of the 3-way sub-switch can be completed. Here, there is no limitation on the specific selection of the decoder, and it can be designed according to the actual situation.

[0081] exist Figure 7 or Figure 8 In the illustrated embodiment, the difference from the other embodiments described above lies in the channel selection unit. The channel selection unit in the previously described embodiment uses a two-choice gate as a control switch, and the decoder directly outputs the selection signal corresponding to each gate. The decoder can be directly set in the control module in the readout chip. The example of the decoder before is only for schematic illustration and is not a limitation on the decoder. In the embodiment here, the control switch described includes several groups of control switch branches. The decoder is used to control the sub-switches in each group of control switch branches to realize the reading of a preset number of continuous groups of signals. In the embodiment described above, the channel selection unit uses a gate as a control switch to realize the reading of fingerprint signals at any position of the TFT optical fingerprint sensor chip and can quickly perform dual-finger fingerprint switching reading. In the design of this channel selection unit, the signal conversion channel group needs to set at least M / 2 signal conversion channels. The reading of each row of fingerprint signals requires M / 2 signal conversion channels to work. In the introduction Figure 7 or Figure 8 In the example shown, although it is not possible to read from any column of TFT photosensitive pixel units, it is also possible to read in a variety of ways according to the modular sequence of the output pads, but the number of signal conversion channels that need to work together each time is PM / Q, for example Figure 8 Therefore, the number of signal conversion channels for each row of fingerprint reading can be reduced, and the power consumption of the readout chip can be reduced to a certain extent compared with the above-described embodiment. Figure 7 or Figure 8 In the embodiment shown in the figure, the decoder can also be integrated in the control module instead of Figure 7 Or 8 indicates that it is listed separately outside the control module.

[0082] The embodiments described above can significantly reduce the number of signal conversion channels in the readout chip corresponding to a large-area TFT optical fingerprint sensor chip, thereby reducing the manufacturing cost of the readout chip.

[0083] like Fig. 9 As shown, a TFT optical fingerprint recognition module is applied to a schematic diagram of an electronic device under the screen. The electronic display screen can be a touch display screen with a touch detection board. The touch detection board can include a touch TP (Touch Panel) and a TP control module. Fig. 9 The touch TP part is not shown in the figure because it will block the TFT optical fingerprint recognition module that needs to be described. The TFT optical fingerprint sensor chip 6 is a large-area photosensitive pixel array made by TFT technology. It is usually made on a glass substrate. Its readout chip can also be set on this glass substrate. In some embodiments, it will also be Fig. 9 As shown, the TFT optical fingerprint recognition module also includes a gate driver chip 5. The TFT optical fingerprint recognition module also includes an optical processing component arranged above the TFT optical fingerprint sensor chip 6, such as an optical collimator or a microlens array, which performs optical processing on the signal light carrying the fingerprint signal before being received by the TFT optical fingerprint sensor chip.

[0084] The area of ​​the TFT optical fingerprint sensor chip is different from the traditional capacitive fingerprint or the traditional optical fingerprint. Since the area of ​​its photosensitive pixel array is usually larger than the area of ​​one or two fingers, the area of ​​the fingerprint recognition area on the screen can be correspondingly expanded. In this module, the area of ​​the readout chip is smaller than the TFT optical fingerprint sensor chip. In the embodiment described above, the number of signal conversion channels in the signal conversion module is less than the number of pixels per row of the TFT optical fingerprint sensor chip.

[0085] In order to reduce the power consumption of the readout chip in the TFT optical fingerprint recognition module, the fingerprint signal can be scanned and read after the position of the finger in the fingerprint recognition area is determined. The TP control module in the touch detection board of the host on the electronic device obtains the current position of the finger in the fingerprint recognition area, and outputs the corresponding information to the control module 20 in the readout chip. The control module controls the decoder to generate a corresponding control signal to the control switch, and reads the signal of the pixel units in the TFT optical fingerprint sensor chip of a specified number and arranged continuously. In the embodiment where the output pad or integrator in the readout chip corresponds one-to-one with a single row of pixels in the TFT optical fingerprint sensor chip, the control module controls the decoder to generate a corresponding control signal to the control switch, and reads the fingerprint signal on the output pad or integrator of a specified number and arranged continuously.

[0086] Based on the TFT optical fingerprint recognition module introduced above, a method for applying the TFT optical fingerprint recognition module to perform fingerprint recognition in an electronic device is further described herein.

[0087] Please refer to Fig.10 The identification method comprises: S1: setting an optical fingerprint identification area on the touch screen of the electronic device; S2: using a touch detection board to detect the position of a finger in the optical fingerprint identification area and transmitting it to a host in the electronic device; S3: the host transmits a control signal to a control module in a TFT optical fingerprint identification module according to the finger position detected by the touch detection board; S4: the control module controls a signal conversion module of the TFT optical fingerprint identification module to convert a photosensitive signal of a photosensitive pixel array corresponding to the finger position.

[0088] Among them, the control module in the TFT optical fingerprint recognition module is the control module in the readout chip in the TFT optical fingerprint recognition module. As described above, the input of the decoder in the channel selection unit in the signal conversion module comes from the control module of the readout chip. In some embodiments, the decoder can also be set in the control module part of the readout chip. In order to expand the area of ​​the area where fingerprint recognition can be performed on the display screen of the electronic device, the area of ​​the photosensitive pixel array in the TFT optical fingerprint sensor chip can be set to be at least larger than the contact area between the two fingers and the optical fingerprint recognition area. Among them, the photosensitive pixel array is made using the TFT process, and the production cost is reduced while making a large-area photosensitive pixel array. While being able to quickly identify the fingerprint signal of a single finger, the fingerprint signal of fingers at different positions can be identified, and the signal conversion channel in the signal conversion channel unit in the readout chip can be reused, and the production cost of the optical fingerprint recognition module can be reduced under the premise of achieving the expected fingerprint recognition performance. In this way, the number of signal conversion channels of the signal conversion channel unit in the readout chip in the TFT optical fingerprint recognition module is also made smaller than the number of single-row photosensitive pixels in the photosensitive pixel array.

[0089] In the above described different readout chip embodiments, the number of signal conversion channels in the signal conversion module may be, for example, 220 signal conversion channels. In the embodiment where the control switch is a two-choice selector, each signal reading will start 220 signal conversion channels to read 220 single-row photosensitive pixel units. However, when the control switch is a plurality of control switch branch groups, although there may be 220 signal conversion channels in the signal conversion module, the number of signal conversion channels selected by the decoder each time is 165. Therefore, according to the specific needs of the TFT optical fingerprint recognition module applied to electronic devices, the control module can control the signal conversion module to convert photosensitive pixels corresponding to the number of signal conversion channels less than or equal to the number of signal conversion channels included in the signal conversion module to collect finger fingerprints.

[0090] At present, the touch screen of electronic devices is mostly a self-luminous screen, and the optical fingerprint recognition area is set on the self-luminous screen, and the light-emitting pixels in the self-luminous screen are used to illuminate the target finger in the optical fingerprint recognition area. However, in other embodiments, when the electronic device does not have a self-luminous display screen, a detection light source for optical fingerprint recognition can also be set separately to detect the finger on the fingerprint recognition area of ​​the electronic device. Here, the touch screen of the electronic device used is not limited to the self-luminous screen.

[0091] Compared with the prior art, the present invention has the following beneficial effects:

[0092] 1. The readout chip of the TFT optical fingerprint sensor chip proposed in the present invention is used to read the fingerprint signal output by the TFT optical fingerprint sensor chip, and includes an integration module, a signal conversion module and a control module. The integration module includes a plurality of integrators, and the integration module is configured to be electrically connected to the output pad in the TFT optical fingerprint sensor chip to receive the signal output by the TFT optical fingerprint sensor chip. The signal conversion module includes a signal conversion channel unit and a channel selection unit, and the signal conversion channel unit includes a plurality of mutually independent signal conversion channels. When the signal conversion channel unit is working, the plurality of signal conversion channels are connected to some integrators in the integration module in a one-to-one correspondence; the channel selection unit is used to connect to the signal conversion channel unit and connect the plurality of signal conversion channels to the plurality of integrators specified in the integration module. The control module is used to connect to the channel selection unit and control the position of the plurality of integrators specified in the channel selection unit in the integration module. Channel multiplexing can be achieved through the cooperation of the signal conversion module and the control module, that is, the channels of two or more integrators can share a signal conversion channel for analog-to-digital conversion. The structure proposed in this application can effectively reduce the number of channels of the entire readout chip and realize channel multiplexing, thereby effectively reducing the chip area and power consumption, and reducing the hardware cost of the circuit to a certain extent. In addition, through the cooperation of the control module and the channel selection unit, continuous selection from any position can be achieved, that is, no matter where the finger touches the TFT optical fingerprint sensor, it can be identified without being limited to a specific place.

[0093] 2. The channel selection unit can be realized through a decoder and several control switches. The cooperation of the decoder and the control switch can realize channel multiplexing and dual-finger switching, so that the TFT optical fingerprint sensor signal readout chip has a dual-finger switching mode, which provides convenience for users to flexibly select finger recognition and enhances reliability.

[0094] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example" or "specific example" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0095] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention. < / m> < / n> < / n> < / n> < / n> < / n> < / n> < / n>

Claims

1. A readout chip of a TFT optical fingerprint sensor chip, used to read the fingerprint signal output by the TFT optical fingerprint sensor chip, It is characterized in that include: An integration module, comprising a plurality of integrators, wherein the integration module is configured to be electrically connected to an output pad in the TFT optical fingerprint sensor chip to receive a signal output by the TFT optical fingerprint sensor chip; The signal conversion module comprises a signal conversion channel unit and a channel selection unit, wherein the signal conversion channel unit comprises a plurality of mutually independent signal conversion channels, and when the signal conversion channel unit is working, the plurality of signal conversion channels are connected to some integrators in the integration module in a one-to-one correspondence; the channel selection unit is used to connect to the signal conversion channel unit and connect the plurality of signal conversion channels to a plurality of integrators specified in the integration module; The control module is used to connect with the channel selection unit and control the positions of several integrators specified in the channel selection unit in the integration module.

2. The readout chip according to claim 1, It is characterized in that The specified plurality of integrators are located at consecutive positions in the integration module.

3. The readout chip according to claim 1, It is characterized in that The number of the specified plurality of integrators is 100-150.

4. The readout chip according to claim 1, It is characterized in that Several integrators in the integration module are connected to output pads in the TFT optical fingerprint sensor chip in a one-to-one correspondence.

5. The readout chip according to claim 1, It is characterized in that The number of the signal conversion channels in the signal conversion channel unit is less than the number of the integrators in the integration module; The channel selection unit is arranged between the signal conversion channel unit and the integration module.

6. The readout chip according to claim 5, It is characterized in that The channel selection unit includes a decoder and a plurality of control switches; The integration module is connected to the designated signal conversion channel unit through the control switch, wherein the designated integrator in the integration module is connected to the signal conversion channel in the signal conversion channel unit in a one-to-one correspondence; The decoder is connected to the plurality of control switches to control the designated integrator to connect to the corresponding signal conversion channel; The control module is connected to the decoder and outputs information of a designated integrator and a corresponding signal conversion channel to the decoder.

7. The readout chip according to claim 6, It is characterized in that The control switch is a two-choice selector.

8. The readout chip according to claim 1, It is characterized in that The signal conversion channel unit includes an analog-to-digital converter.

9. A TFT optical fingerprint recognition module is applied to an electronic device, wherein the electronic device has a host, the TFT optical fingerprint recognition module communicates with the host, and the electronic device has a TFT optical fingerprint recognition area. It is characterized in that The TFT optical fingerprint recognition module includes: A touch detection board, used to communicate with the host and detect the position of the finger in the TFT optical fingerprint recognition area; TFT optical fingerprint sensor chip, with TFT photosensitive pixels distributed in an array, receiving light signals carrying fingerprints; and The readout chip according to claim 1, wherein the readout chip is connected to the TFT optical fingerprint sensor chip and communicates with the host; Among them, the area of ​​the readout chip is smaller than the area of ​​the TFT optical fingerprint sensor chip, and the number of channels in the signal conversion module in the readout chip is less than the number of pixels in each row of the TFT optical fingerprint sensor chip; when the readout chip is working, the signal conversion module converts the signals output by a specified number of continuously arranged integrators in the integration module.

10. A TFT optical fingerprint recognition method, applied to an electronic device, wherein the electronic device comprises a TFT optical fingerprint recognition module, It is characterized in that The TFT optical fingerprint recognition module comprises a readout chip of the TFT optical fingerprint sensor chip according to any one of claims 1 to 8; the recognition method comprises: Setting an optical fingerprint recognition area on the touch screen of the electronic device; Using a touch detection panel to detect the position of a finger in the optical fingerprint recognition area and transmit it to a host in the electronic device; The host transmits a control signal to the control module in the TFT optical fingerprint recognition module according to the finger position detected by the touch detection board; The control module controls the signal conversion module of the TFT optical fingerprint recognition module to convert the photosensitive signal of the photosensitive pixel array corresponding to the finger position; Among them, the area of ​​the photosensitive pixel array is set to be at least larger than the contact area between the two fingers and the optical fingerprint recognition area, the number of signal conversion channels of the signal conversion channel unit in the readout chip in the TFT optical fingerprint recognition module is less than the number of photosensitive pixels in a single row of the photosensitive pixel array; the control module controls the signal conversion module to convert the photosensitive pixels corresponding to the number of signal conversion channels less than or equal to the number of signal conversion channels included in the signal conversion module to collect finger fingerprints.

11. The TFT optical fingerprint recognition method according to claim 10, It is characterized in that The touch screen of the electronic device is a self-luminous screen, the optical fingerprint recognition area is arranged on the self-luminous screen, and the luminous pixels in the self-luminous screen are used to illuminate the target finger in the optical fingerprint recognition area.

Images