Fingerprint reading circuit, fingerprint identification module, display assembly and electronic equipment

Abstract

The invention discloses a fingerprint reading circuit, a fingerprint identification module, a display assembly and electronic equipment, and belongs to the technical field of fingerprint detection. The fingerprint reading circuit comprises an operational amplifier, and the inverted input end of the operational amplifier is connected with the induction electrode; the first end of the feedback capacitor is connected with the inverted input end of the operational amplifier, and the second end of the feedback capacitor is connected with the output end of the operational amplifier; the first end of the bleeder circuit is connected with the induction electrode, and the second end of the bleeder circuit is grounded; or the first end of the bleeder circuit is connected with the first end of the feedback capacitor, and the second end of the bleeder circuit is connected with the second end of the feedback capacitor.

Description

Technical Field

[0001] The present application belongs to the field of fingerprint detection technology, and specifically relates to a fingerprint reading circuit, a fingerprint recognition module, a display component and an electronic device. Background Art

[0002] The fingerprint reading circuit used in the fingerprint sensor can read the change in signal capacitance before and after the user's finger touches it, and the change in signal capacitance can reflect the fingerprint data of the finger.

[0003] In the related technical solutions, the anti-static ability of the fingerprint reading circuit is relatively poor. If the user's finger or the anti-static gun carries static electricity, the static electricity may damage the operational amplifier in the fingerprint reading circuit, affecting the reliability of the fingerprint reading circuit. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a fingerprint reading circuit, a fingerprint recognition module, a display component and an electronic device, which can improve the problem of poor anti-static ability of the fingerprint reading circuit.

[0005] In a first aspect, an embodiment of the present application provides a fingerprint reading circuit for a fingerprint sensor, the fingerprint sensor includes a sensing electrode, and the fingerprint reading circuit includes: an operational amplifier, the inverting input terminal of the operational amplifier is connected to the sensing electrode; a feedback capacitor, the first end of the feedback capacitor is connected to the inverting input terminal of the operational amplifier, and the second end of the feedback capacitor is connected to the output terminal of the operational amplifier; a discharge circuit, the first end of the discharge circuit is connected to the sensing electrode, and the second end of the discharge circuit is grounded; or the first end of the discharge circuit is connected to the first end of the feedback capacitor, and the second end of the discharge circuit is connected to the second end of the feedback capacitor.

[0006] In a second aspect, an embodiment of the present application provides a fingerprint recognition module, including: a fingerprint sensor, the fingerprint sensor including a sensing electrode; and a fingerprint reading circuit as described in any one of the first aspects.

[0007] In a third aspect, an embodiment of the present application provides a display component, including: a display screen; and a fingerprint recognition module as described in any one of the second aspects.

[0008] In a fourth aspect, an embodiment of the present application provides an electronic device, comprising: a fingerprint recognition module as described in any one of the second aspect; and / or a display component as described in the third aspect.

[0009] In an embodiment of the present application, the proposed fingerprint reading circuit includes an operational amplifier, a feedback capacitor and a discharge circuit. Among them, the inverting input terminal of the operational amplifier is connected to the sensing electrode in the fingerprint sensor. At this time, the fingerprint sensor can be used to sense the pressure of the user's finger, and the change in the signal capacitance caused by the pressure of the user's finger is input into the inverting input terminal of the operational amplifier, and the operational amplifier is used for output. In this process, compared with the operational amplifier, the equivalent impedance of the set discharge circuit is relatively small. Therefore, when the sensing electrode in the fingerprint sensor releases the charge due to static electricity, the charge will preferentially flow through the discharge circuit for discharge and absorption. Obviously, the amount of charge flowing through the operational amplifier can be reduced, thereby protecting the operational amplifier and improving the anti-static ability of the fingerprint reading circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a topological schematic diagram of a fingerprint reading circuit in a related technical solution;

[0011] Figure 2 It is a schematic diagram of the principle of a fingerprint reading circuit in a related technical solution;

[0012] Figure 3 An image showing that the operational amplifier is not damaged before air discharge in the related technical solution;

[0013] Figure 4 An image showing damage to an operational amplifier after air discharge in a related technical solution is shown;

[0014] Figure 5 It is a working schematic diagram of a fingerprint reading circuit in a related technical solution;

[0015] Figure 6 It is one of the topological schematic diagrams of the fingerprint reading circuit provided in some embodiments of the present application;

[0016] Figure 7 This is the second topological schematic diagram of the fingerprint reading circuit provided in some embodiments of the present application;

[0017] Figure 8 This is the third topological schematic diagram of the fingerprint reading circuit provided in some embodiments of the present application;

[0018] Fig. 9 This is a fourth topological schematic diagram of a fingerprint reading circuit provided in some embodiments of the present application;

[0019] Fig.10 is a topological schematic diagram of a discharge circuit provided in some embodiments of the present application;

[0020] Fig.11 is a schematic diagram of the structure of a display assembly provided in some embodiments of the present application;

[0021] Fig.12 is a topological diagram of a fingerprint recognition module provided in some embodiments of the present application;

[0022] Fig.13 is one of the schematic diagrams of control signals provided in some embodiments of the present application;

[0023] Fig.14 This is the second schematic diagram of the control signal provided in some embodiments of the present application;

[0024] Fig.15 This is a third schematic diagram of a control signal provided in some embodiments of the present application;

[0025] Fig.16 This is a fourth schematic diagram of a control signal provided in some embodiments of the present application;

[0026] Fig.17 This is a fifth schematic diagram of control signals provided in some embodiments of the present application;

[0027] Fig.18 This is the fifth schematic diagram of the control signal provided in some embodiments of the present application.

[0028] Attached Figure 1 , Figure 2 , Figure 5 Markings:

[0029] U' operational amplifier, C FB 'Feedback capacitor, Pixel' sensing electrode, Cf signal capacitor, Passivation layer' isolation layer.

[0030] Attached Figures 6 to 12 Markings:

[0031] 100 fingerprint reading circuit, 200 fingerprint sensor, Pixel sensing electrode, U operational amplifier, C FB Feedback capacitor, 102 discharge circuit, 1022 discharge subcircuit, R S Current limiting resistor, S1 first switch, C1 first capacitor, R1 first resistor, S 11 The first sub-switch, R 11 The first sub-resistance, C 11 The first sub-capacitor, 300 fingerprint recognition module, 202 isolation layer, A working surface, B non-working surface, 400 display component, 402 display screen. DETAILED DESCRIPTION

[0032] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0033] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0034] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] Figure 1 is a topological diagram of a fingerprint reading circuit in a related technical solution, Figure 2 is a schematic diagram of the principle of the fingerprint reading circuit in the related technical solution, such as Figure 1 and Figure 2 As shown, the fingerprint reading circuit includes an operational amplifier U', a feedback capacitor C FB ', where the feedback capacitor C FB The two ends of ' are respectively connected to the inverting input terminal and the output terminal of the operational amplifier U', the inverting input terminal of the operational amplifier U' is connected to the sensing electrode Pixel' of the fingerprint sensor, wherein the sensing electrode Pixel' is covered with an isolation layer Passivation layer', wherein the parasitic capacitance of the sensing electrode Pixel' of the fingerprint sensor to the ground is represented by Cp1, the parasitic capacitance of the finger to the ground is represented by Cp2, and Cf is the signal capacitance.

[0036] Normally, Cp2 is much larger than Cf. When the excitation signal Vin is input to the non-inverting input terminal of the operational amplifier U', the output terminal of the operational amplifier U' outputs Vout, where the expression of Vout is:

[0037] Vout=Vin×(1+Cp1 / C FB '+Cf / C FB ')

[0038] Among them, Vout is the signal output from the output end of the operational amplifier U', Vin is the excitation signal input to the non-inverting input end of the operational amplifier U', Cp1 is the parasitic capacitance of the sensing electrode Pixel' of the fingerprint sensor to the ground, and Cp2 is the parasitic capacitance of the finger to the ground.

[0039] Wherein, Cf is a signal capacitor, and the change of its capacitance can reflect the fingerprint data. Therefore, the output Vout of the output terminal of the operational amplifier U' also reflects the change of the capacitance and the fingerprint data.

[0040] In addition to being added to the non-inverting input terminal of the operational amplifier U', the excitation signal Vin can also be directly added to the finger, such as through a metal ring.

[0041] Figure 3 The image shows that the operational amplifier is not damaged before the air discharge in the related technical solution. Figure 4 The image of the operational amplifier being damaged after air discharge in the related technical solution is shown. Figure 3 and Figure 4 As shown in the figure, before and after the air discharge, a bad spot appears at the location of the operational amplifier. At this time, it is considered that the operational amplifier is damaged.

[0042] Specifically, Figure 5 is a working schematic diagram of a fingerprint reading circuit in a related technical solution, such as Figure 5 As shown, when the finger or the electrostatic gun carries static electricity, the finger or the electrostatic gun and the sensing electrode Pixel' in the fingerprint sensor, that is, the pixel point, form a signal capacitor Cf, and negative charge will accumulate on the sensing electrode Pixel'. At the moment of static electricity release, the negative charge accumulated on the sensing electrode Pixel' will also be released, forming a discharge path shown by the arrow, one of which passes through the operational amplifier U'. Since the equivalent impedance of the inverting input terminal of the operational amplifier U' is relatively small, usually several thousand ohms, it is easy to damage the operational amplifier U', causing damage to the operational amplifier U'.

[0043] The fingerprint reading circuit, fingerprint recognition module, display component and electronic device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings through specific embodiments and their application scenarios.

[0044] In some embodiments of the present application, Figure 6 and Figure 7As shown, a fingerprint reading circuit 100 is proposed, which is used for a fingerprint sensor 200. The fingerprint sensor 200 includes a sensing electrode Pixel. The fingerprint reading circuit 100 includes: an operational amplifier U, the inverting input terminal of the operational amplifier U is connected to the sensing electrode Pixel; a feedback capacitor C FB , feedback capacitor C FB The first end is connected to the inverting input terminal of the operational amplifier U, and the feedback capacitor C FB The second end of the discharge circuit 102 is connected to the output end of the operational amplifier U; the discharge circuit 102, the first end of the discharge circuit 102 is connected to the sensing electrode Pixel, and the second end of the discharge circuit 102 is grounded; or the first end of the discharge circuit 102 is connected to the feedback capacitor C FB The first end of the discharge circuit 102 is connected to the feedback capacitor C FB The second end of the connection.

[0045] In the embodiment of the present application, the fingerprint reading circuit 100 includes an operational amplifier U, a feedback capacitor C FB And the discharge circuit 102. Among them, the inverting input terminal of the operational amplifier U is connected to the sensing electrode Pixel in the fingerprint sensor 200. At this time, the fingerprint sensor 200 can be used to sense the pressure of the user's finger, and the change in the signal capacitance caused by the pressure of the user's finger is input to the inverting input terminal of the operational amplifier U, and the operational amplifier U is used for output. In this process, compared with the operational amplifier U, the equivalent impedance of the set discharge circuit 102 is relatively small. Therefore, when the sensing electrode Pixel in the fingerprint sensor 200 releases the charge due to static electricity, the charge will preferentially flow through the discharge circuit 102 for discharge and absorption. Obviously, the amount of charge flowing through the operational amplifier U can be reduced, thereby protecting the operational amplifier U and improving the anti-static ability of the fingerprint reading circuit 100.

[0046] In some embodiments of the present application, the fingerprint reading circuit 100 further includes: a current limiting resistor Rs, which is connected in series with the feedback capacitor C FB between the first end and the inverting input terminal of the operational amplifier U.

[0047] In this embodiment, the current limiting resistor Rs is connected in series with the feedback capacitor C FB Between the first end of and the inverting input terminal of the operational amplifier U, therefore, the resistance value in the loop where the inverting input terminal of the operational amplifier U is located can be increased, and when the voltage input to the inverting input terminal of the operational amplifier U remains unchanged, the current flowing through the inverting input terminal of the operational amplifier U can be reduced.

[0048] In this process, the current flowing through the operational amplifier U can be limited, reducing the probability of the operational amplifier U being damaged due to overcurrent, thereby improving the reliability of the operational amplifier U and the reliability of the fingerprint reading circuit 100.

[0049] In some embodiments of the present application, the resistance value of the current limiting resistor Rs can be determined according to actual usage requirements, which will not be elaborated here.

[0050] In some embodiments of the present application, the discharge circuit 102 includes: a first switch S1; a first capacitor C1; a first resistor R1, and the second end of the first resistor R1 is connected to the first end of the first capacitor C1; when the first end of the discharge circuit 102 is connected to the sensing electrode Pixel and the second end of the discharge circuit 102 is grounded, the first end of the first switch S1 is connected to the sensing electrode Pixel, the second end of the first switch S1 is connected to the first end of the first resistor R1, and the second end of the first capacitor C1 is grounded; or the first end of the first resistor R1 is connected to the sensing electrode Pixel, the second end of the first capacitor C1 is connected to the first end of the first switch S1, and the second end of the first switch S1 is grounded; when the first end of the discharge circuit 102 is connected to the feedback capacitor C FB The first end of the discharge circuit 102 is connected to the feedback capacitor C FB When the second end of the first switch S1 is connected to the feedback capacitor C FB The first end of the first switch S1 is connected to the first end of the first resistor R1, and the second end of the first capacitor C1 is connected to the feedback capacitor C FB or the first end of the first resistor R1 is connected to the feedback capacitor C FB The first end of the first capacitor C1 is connected to the first end of the first switch S1, and the second end of the first switch S1 is connected to the feedback capacitor C FB wherein, when the fingerprint sensor 200 is not in a working state, the first switch S1 is in a conducting state, and when the fingerprint sensor 200 is in a working state, the first switch S1 is in a disconnected state.

[0051] In this embodiment, the discharge circuit 102 includes a first switch S1, a first capacitor C1 and a first resistor R1, wherein the first capacitor C1 and the first resistor R1 form a low impedance loop. When charges are accumulated and released on the sensing electrode Pixel, the charges can preferentially pass through the low impedance loop formed by the first capacitor C1 and the first resistor R1, and are absorbed by the low impedance loop formed by the first capacitor C1 and the first resistor R1. Since most of the charges are absorbed by the low impedance loop formed by the first capacitor C1 and the first resistor R1, and the charges flowing through the operational amplifier U become less, the probability of damage to the operational amplifier U can be reduced, thereby improving the reliability of the fingerprint reading circuit 100.

[0052] In the above embodiment, the first switch S1 is set so as to use the first switch S1 to control whether the low impedance loop composed of the first capacitor C1 and the first resistor R1 is connected. In this process, if the low impedance loop composed of the first capacitor C1 and the first resistor R1 is always connected, when the fingerprint sensor 200 is in the working state, the first capacitor C1 will affect the detection ability of the fingerprint reading circuit 100 for the signal capacitance, so that the fingerprint reading circuit 100 cannot accurately read the user's fingerprint data, and the fingerprint reading circuit 100 cannot work normally.

[0053] Based on this, the first switch S1 is set so that the first switch S1 is used to control whether the low impedance loop composed of the first capacitor C1 and the first resistor R1 is connected, so that when the fingerprint sensor 200 is not in a working state, the low impedance loop composed of the first capacitor C1 and the first resistor R1 is connected, and when the fingerprint sensor 200 is in a working state, the connection of the low impedance loop composed of the first capacitor C1 and the first resistor R1 is cut off, so as to ensure the reliable operation of the fingerprint reading circuit 100.

[0054] Specifically, the capacitance value of the first capacitor C1 is much larger than the capacitance value of the signal capacitor, so that the fingerprint reading circuit 100 cannot accurately detect the size of the signal capacitor. When the signal capacitor cannot be detected, the fingerprint data cannot be read. When the fingerprint sensor 200 is in working state, cutting off the access of the low-impedance loop composed of the first capacitor C1 and the first resistor R1 can eliminate the influence of the first capacitor C1 on the signal capacitor, thereby ensuring the reliable operation of the fingerprint reading circuit 100.

[0055] Specifically, Figure 6 As shown, when the fingerprint sensor 200 is not in working state, the first switch S1 is in the on state. When the finger or the electrostatic gun carries static electricity, the finger or the electrostatic gun and the sensing electrode Pixel of the fingerprint sensor 200, that is, the pixel point, form a signal capacitor, and negative charge will accumulate on the sensing electrode Pixel. At the moment of static electricity release, the negative charge accumulated on the sensing electrode Pixel will also be released, forming a discharge path shown by the arrow, wherein the branch of the first resistor R1 and the first capacitor C1 forms a low-impedance loop, and the charge preferentially takes the low-impedance path, and most of the negative charge is absorbed by this branch.

[0056] In addition, a current limiting resistor Rs is added to the inverting input terminal of the operational amplifier U, which increases the input resistance of the inverting input terminal of the operational amplifier U and further reduces the negative charge flowing through the operational amplifier U, thereby achieving the purpose of protecting the readout circuit.

[0057] Specifically, Figure 8As shown, when the fingerprint sensor 200 is working, due to the addition of the first resistor R1 and the first capacitor C1, if the first switch S1 is turned on, since the first capacitor C1 will be much larger than the signal capacitor formed by the finger and the electrode, the size of the signal capacitor cannot be accurately detected, affecting the fingerprint reading performance. Therefore, when the fingerprint sensor 200 is working, the first switch S1 is turned off, which can ensure that the fingerprint reading performance is not affected by the first capacitor C1.

[0058] Specifically, Figure 7 As shown, when the fingerprint sensor 200 is not working, the first switch S1 is turned on. When the finger or the electrostatic gun carries static electricity, the finger or the electrostatic gun and the sensing electrode Pixel of the fingerprint sensor 200, that is, the pixel, form a signal capacitor, and negative charge will accumulate on the sensing electrode Pixel. At the moment of static electricity release, the negative charge accumulated on the sensing electrode Pixel will also be released, forming a discharge path shown by the arrow.

[0059] Among them, the branch of the first resistor R1 and the first capacitor C1 forms a low-impedance loop, and the charge preferentially takes the low-impedance path. Most of the negative charge is absorbed by this branch. In addition, a current limiting resistor Rs is added to the inverting input terminal of the operational amplifier U, which increases the input resistance of the inverting input terminal of the operational amplifier U, further reducing the negative charge flowing through the operational amplifier U, thereby achieving the purpose of protecting the readout circuit.

[0060] Specifically, Fig. 9 As shown, when the fingerprint sensor 200 is working, due to the addition of the first resistor R1 and the first capacitor C1, if the first switch S1 is turned on, since the first capacitor C1 will be much larger than the signal capacitor formed by the finger and the electrode, the size of the signal capacitor cannot be accurately detected, affecting the fingerprint reading performance. Therefore, when the fingerprint sensor 200 is working, the first switch S1 is turned off to ensure that the fingerprint reading performance is not affected by the first capacitor C1.

[0061] In the above embodiment, the anti-static capability of the fingerprint reading circuit 100 can be improved at a very low cost, thereby improving the reliability of the fingerprint reading circuit 100.

[0062] In some embodiments of the present application, the discharge circuit 102 includes: at least two discharge sub-circuits 1022, different discharge sub-circuits 1022 are connected in parallel, and each discharge sub-circuit 1022 includes a first sub-switch S 11 , the first sub-resistance R 11 and the first sub-capacitor C 11 , the first sub-resistance R 11 The second end of the first sub-capacitor C 11 The first end of each discharge sub-circuit 1022 is connected to the first sub-resistance R 11 The resistance value and the first sub-capacitor C 11When the first end of the discharge circuit 102 is connected to the sensing electrode Pixel and the second end of the discharge circuit 102 is grounded, the first sub-switch S 11 The first end of the first sub-switch S is connected to the sensing electrode Pixel. 11 The second end of the first sub-resistance R 11 The first end of the first sub-capacitor C 11 The second end of the first sub-resistance R 11 The first end of the first sub-capacitor C is connected to the sensing electrode Pixel. 11 The second end of the first sub switch S 11 The first end of the first sub-switch S 11 The second end of the discharge circuit 102 is connected to the feedback capacitor C FB The first end of the discharge circuit 102 is connected to the feedback capacitor C FB When the second end of the first sub-switch S is connected 11 The first terminal of the feedback capacitor C FB The first end of the first sub-switch S 11 The second end of the first sub-resistance R 11 The first end of the first sub-capacitor C 11 The second terminal of the feedback capacitor C FB or the second end of the first sub-resistance R 11 The first terminal of the feedback capacitor C FB The first end of the first sub-capacitor C 11 The second end of the first sub switch S 11 The first end of the first sub-switch S 11 The second terminal of the feedback capacitor C FB wherein, when the fingerprint sensor 200 is not in the working state, the first sub-switch S in the target discharge sub-circuit in at least two discharge sub-circuits 1022 11 In the on state, when the fingerprint sensor 200 is in the working state, the first sub-switch S in the target discharge sub-circuit 11 In disconnected state.

[0063] In this embodiment, the discharge circuit 102 is composed of a plurality of discharge sub-circuits 1022 connected in parallel, wherein the first sub-resistors R 11 The resistance value and the first sub-capacitor C 11 The capacitance values ​​are different. Therefore, one discharge subcircuit 1022 can be selected from the at least two discharge subcircuits 1022 as the target discharge subcircuit, and when the fingerprint sensor 200 is not in the working state, the first sub-switch S in the target discharge subcircuit of the at least two discharge subcircuits 1022 is switched off.11 In the on state, when the fingerprint sensor 200 is in the working state, the first sub-switch S in the target discharge sub-circuit 11 In disconnected state.

[0064] In this embodiment, different discharge sub-circuits 1022 may be selected and controlled according to different requirements to meet the usage requirements of different scenarios.

[0065] Specifically, Fig.10 As shown, the first sub-switch S in each discharge sub-circuit 1022 11 , the first sub-resistance R 11 and the first sub-capacitor C 11 The connection mode of the first switch S1, the first capacitor C1 and the first resistor R1 is the same as that of the first switch S1, the first capacitor C1 and the first resistor R1, which will not be repeated here.

[0066] In some embodiments of the present application, the first sub-resistor R in different discharge sub-circuits 1022 11 and the first sub-capacitor C 11 The chip registers can be used for configuration, and the specific configuration process will not be described here.

[0067] In some embodiments of the present application, a fingerprint recognition module 300 is proposed, such as Figure 6 and Figure 7 As shown, it includes: a fingerprint sensor 200, the fingerprint sensor 200 includes a sensing electrode Pixel; and a fingerprint reading circuit 100 as any one of the above items.

[0068] In this embodiment, the proposed fingerprint recognition module 300 includes a fingerprint sensor 200 and a fingerprint reading circuit 100 as in any of the above embodiments. The proposed fingerprint reading circuit 100 includes an operational amplifier U, a feedback capacitor C FB And the discharge circuit 102. Among them, the inverting input terminal of the operational amplifier U is connected to the sensing electrode Pixel in the fingerprint sensor 200. At this time, the fingerprint sensor 200 can be used to sense the pressure of the user's finger, and the change in the signal capacitance caused by the pressure of the user's finger is input to the inverting input terminal of the operational amplifier U, and the operational amplifier U is used for output. In this process, compared with the operational amplifier U, the equivalent impedance of the set discharge circuit 102 is relatively small. Therefore, when the sensing electrode Pixel in the fingerprint sensor 200 releases the charge due to static electricity, the charge will preferentially flow through the discharge circuit 102 for discharge and absorption. Obviously, the amount of charge flowing through the operational amplifier U can be reduced, thereby protecting the operational amplifier U and improving the anti-static ability of the fingerprint reading circuit 100.

[0069] In some embodiments of the present application, Figure 6 and Figure 7 As shown, the fingerprint identification module 300 further includes: an isolation layer 202, the isolation layer 202 has a working surface A and a non-working surface B, the working surface A and the non-working surface B are arranged opposite to each other, and the sensing electrode Pixel is arranged in contact with the non-working surface B.

[0070] In this embodiment, the isolation layer 202 is provided to isolate the sensing electrode Pixel from the working environment, thereby preventing the finger from directly contacting the sensing electrode Pixel and reducing the dust adsorbed by the sensing electrode Pixel, thereby improving the reliability of the fingerprint reading circuit 100.

[0071] In some embodiments of the present application, the isolation layer 202 is a resin isolation layer 202 or a glass isolation layer 202 .

[0072] In some embodiments of the present application, Fig.11 As shown, a display component 400 is proposed, including: a display screen 402; and a fingerprint recognition module 300 as any one of the above items.

[0073] In this embodiment, the proposed display assembly 400 includes a display screen 402 and a fingerprint recognition module 300 as in any of the above embodiments. The fingerprint reading circuit 100 in the fingerprint recognition module 300 includes an operational amplifier U, a feedback capacitor C FB And the discharge circuit 102. Among them, the inverting input terminal of the operational amplifier U is connected to the sensing electrode Pixel in the fingerprint sensor 200. At this time, the fingerprint sensor 200 can be used to sense the pressure of the user's finger, and the change in the signal capacitance caused by the pressure of the user's finger is input to the inverting input terminal of the operational amplifier U, and the operational amplifier U is used for output. In this process, compared with the operational amplifier U, the equivalent impedance of the set discharge circuit 102 is relatively small. Therefore, when the sensing electrode Pixel in the fingerprint sensor 200 releases the charge due to static electricity, the charge will preferentially flow through the discharge circuit 102 for discharge and absorption. Obviously, the amount of charge flowing through the operational amplifier U can be reduced, thereby protecting the operational amplifier U and improving the anti-static ability of the fingerprint reading circuit 100.

[0074] In some embodiments of the present application, the fingerprint recognition module 300 is integrated with the display screen 402, and when pressure is detected in the area of ​​the display screen 402 corresponding to the fingerprint recognition module 300, the fingerprint sensor 200 enters a working state.

[0075] In this embodiment, the working state of the fingerprint sensor 200 can be controlled according to whether the display screen 402 is pressed. In this process, the on or off of the first switch S1 can be controlled according to the working state of the fingerprint sensor 200, so as to ensure that the fingerprint reading performance is not affected by the first capacitor C1.

[0076] Specifically, Fig.12 As shown, the parasitic capacitance of the sensing electrode Pixel of the fingerprint sensor 200 to the ground SGND is represented by Cp1, and the transmitting end TX of the fingerprint sensor 200 outputs a control signal, wherein AVDD is the input voltage, and the input voltage is connected to the fingerprint sensor 200 through a switch, and the switch is controlled by the control signal output by the transmitting end TX of the fingerprint sensor 200. At the same time, the input voltage is converted into a high voltage HV through a boost part, and the high voltage is connected to the fingerprint sensor 200 after passing through another switch, and the voltage is controlled by TXN, wherein TXN is the inverted control signal of TX, GND is the ground corresponding to the input voltage, and SVDD is the signal input to the fingerprint sensor 200.

[0077] The boost part may be a boost circuit or a charge pump.

[0078] Based on this, the control logic of the first switch includes:

[0079] 1. When the fingerprint sensor is not working, the first switch maintains a high level, that is, a conducting state, wherein a high level signal such as Fig.13 shown.

[0080] 2. When the screen detects finger pressure, the fingerprint sensor starts working and the first switch switches to a low level, that is, the off state.

[0081] Specifically, after detecting a finger press, the display screen sends an interrupt signal to the main control chip, wherein the screen outputs the following after detecting a finger press: Fig.14 The interrupt signal shown in Figure 1, where INT is the high level voltage in the interrupt signal. After receiving the interrupt signal, the main control chip resets the fingerprint sensor. The reset signal is as follows: Fig.15 As shown in the figure, / RST is the high level voltage in the reset signal. After the fingerprint sensor completes the reset, Fig.16 As shown, the first switch S1 switches from a high level to a low level, and the first switch is turned off; Fig.17 As shown, after the fingerprint sensor completes the reset, the chip select signal synchronously selects the fingerprint sensor and starts the serial peripheral interface (Serial Peripheral Interface, SPI) communication, where SPI_CS is the high level voltage in the SPI communication; after completing the chip select, the SPI starts to transmit data and the fingerprint sensor collects data.

[0082] Specifically, Fig.18 As shown, two data transmission lines SPI_MOSI and SPI_MOSO are used for transmission, wherein the master device data is input (Master Out Slave In, MOSI) and the master device data is output (Master Out Slave Out, MOSO).

[0083] In some embodiments of the present application, an electronic device is proposed, comprising: a fingerprint recognition module as in any one of the above embodiments; and / or a display component as in any one of the above embodiments.

[0084] In some embodiments of the present application, the electronic device may be a mobile phone, a tablet computer, a laptop computer, a PDA, an in-vehicle electronic device, a mobile Internet device (MID), an augmented reality (AR) / virtual reality (VR) device, a robot, a wearable device, an ultra-mobile personal computer (UMPC), a netbook or a personal digital assistant (PDA), etc. It may also be a server, a network attached storage (NAS), a personal computer (PC), a television (TV), a teller machine or a self-service machine, etc., and the embodiments of the present application are not specifically limited.

[0085] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" 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 application. In this specification, the schematic representation of the above terms does 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 or examples in a suitable manner.

[0086] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A fingerprint reading circuit for a fingerprint sensor, characterized in that: The fingerprint sensor includes a sensing electrode, and the fingerprint reading circuit includes: an operational amplifier, wherein an inverting input terminal of the operational amplifier is connected to the sensing electrode; A feedback capacitor, wherein a first end of the feedback capacitor is connected to an inverting input end of the operational amplifier, and a second end of the feedback capacitor is connected to an output end of the operational amplifier; A discharge circuit, wherein a first end of the discharge circuit is connected to the sensing electrode, and a second end of the discharge circuit is grounded; or a first end of the discharge circuit is connected to a first end of the feedback capacitor, and a second end of the discharge circuit is connected to a second end of the feedback capacitor.

2. The fingerprint reading circuit according to claim 1, characterized in that: The fingerprint reading circuit also includes: A current limiting resistor is connected in series between the first end of the feedback capacitor and the inverting input end of the operational amplifier.

3. The fingerprint reading circuit according to claim 1 or 2, characterized in that: The discharge circuit comprises: First switch; a first capacitor; a first resistor, wherein a second end of the first resistor is connected to a first end of the first capacitor; In the case where the first end of the discharge circuit is connected to the sensing electrode and the second end of the discharge circuit is grounded, the first end of the first switch is connected to the sensing electrode, the second end of the first switch is connected to the first end of the first resistor, and the second end of the first capacitor is grounded; or the first end of the first resistor is connected to the sensing electrode, the second end of the first capacitor is connected to the first end of the first switch, and the second end of the first switch is grounded; In the case where the first end of the discharge circuit is connected to the first end of the feedback capacitor and the second end of the discharge circuit is connected to the second end of the feedback capacitor, the first end of the first switch is connected to the first end of the feedback capacitor, the second end of the first switch is connected to the first end of the first resistor, and the second end of the first capacitor is connected to the second end of the feedback capacitor; or the first end of the first resistor is connected to the first end of the feedback capacitor, the second end of the first capacitor is connected to the first end of the first switch, and the second end of the first switch is connected to the second end of the feedback capacitor; Wherein, when the fingerprint sensor is not in a working state, the first switch is in an on state, and when the fingerprint sensor is in a working state, the first switch is in an off state.

4. The fingerprint reading circuit according to claim 1 or 2, characterized in that: The discharge circuit comprises: at least two discharge sub-circuits, different discharge sub-circuits are connected in parallel, each of the discharge sub-circuits comprises a first sub-switch, a first sub-resistor and a first sub-capacitor, the second end of the first sub-resistor is connected to the first end of the first sub-capacitor, and the resistance value of the first sub-resistor and the capacitance value of the first sub-capacitor in different discharge sub-circuits are different; In the case where the first end of the discharge circuit is connected to the sensing electrode and the second end of the discharge circuit is grounded, the first end of the first sub-switch is connected to the sensing electrode, the second end of the first sub-switch is connected to the first end of the first sub-resistor, and the second end of the first sub-capacitor is grounded; or the first end of the first sub-resistor is connected to the sensing electrode, the second end of the first sub-capacitor is connected to the first end of the first sub-switch, and the second end of the first sub-switch is grounded; In the case where the first end of the discharge circuit is connected to the first end of the feedback capacitor and the second end of the discharge circuit is connected to the second end of the feedback capacitor, the first end of the first sub-switch is connected to the first end of the feedback capacitor, the second end of the first sub-switch is connected to the first end of the first sub-resistor, and the second end of the first sub-capacitor is connected to the second end of the feedback capacitor; or the first end of the first sub-resistor is connected to the first end of the feedback capacitor, the second end of the first sub-capacitor is connected to the first end of the first sub-switch, and the second end of the first sub-switch is connected to the second end of the feedback capacitor; Wherein, when the fingerprint sensor is not in a working state, the first sub-switch in a target discharge sub-circuit of the at least two discharge sub-circuits is in an on state, and when the fingerprint sensor is in a working state, the first sub-switch in the target discharge sub-circuit is in an off state.

5. A fingerprint recognition module, characterized in that: include: A fingerprint sensor, the fingerprint sensor comprising a sensing electrode; The fingerprint reading circuit according to any one of claims 1 to 4.

6. The fingerprint recognition module according to claim 5, characterized in that: Also includes: The isolation layer comprises a working surface and a non-working surface. The working surface is arranged opposite to the non-working surface. The sensing electrode is arranged in contact with the non-working surface.

7. The fingerprint recognition module according to claim 6, characterized in that: The isolation layer is a resin isolation layer or a glass isolation layer.

8. A display component, characterized in that: include: Display screen; A fingerprint recognition module as claimed in any one of claims 5 to 7.

9. The display assembly according to claim 8, characterized in that: The fingerprint recognition module is integrated with the display screen, and when a pressure is detected in the area of ​​the display screen corresponding to the fingerprint recognition module, the fingerprint sensor enters a working state.

10. An electronic device, characterized in that: include: The fingerprint recognition module according to any one of claims 5 to 7; and / or A display assembly as claimed in claim 8 or 9.

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