TW202326660A - Strong light afterimage removal circuit, in-display fingerprint recognition device, image sensing device, and information processing device without affecting the fill factor of the image sensing module, and occupying the chip circuit area - Google Patents

Abstract

The invention mainly discloses a strong light afterimage removal circuit, which is applied in an image sensing device including an image sensing module, a readout integrated circuit (ROIC), and a power management circuit. The strong light afterimage removal circuit includes a charge erasing voltage generating unit controlled by an enabling signal. When the enabling signal has a high level, the charge erasing voltage generating unit generates a positive voltage to a bias voltage terminal of the image sensing module according to a first voltage and a second voltage received from the power management circuit. In this way, the residual charges in the capacitors included in the plural pixel units of the image sensing module are removed. It is worth noting that the image sensing module and the readout integrated circuit (ROIC) are arranged on a substrate, and the strong light afterimage removal circuit of the invention is arranged together with the power management circuit on a flexible circuit board coupled to the substrate. Therefore, the fill factor of the image sensing module will not be affected, and meanwhile the chip circuit area will not be occupied.

Description

Strong light afterimage removal circuit, under-screen fingerprint recognition device, image sensing device, and information processing device

The present invention relates to the technical field of image sensing, in particular to a strong light afterimage removal circuit for integration in an image sensing device or an electronic device with an under-screen fingerprint recognition function for use in image sensing Before the detector implements image sensing, the residual charge of the image sensor caused by strong light is removed first, so as to realize the removal of strong light residual image.

Biometric identification technology is based on collecting the inherent physiological characteristics of the human body as the basis for individual biological identification, such as: iris (Iris), face (Face), voiceprint (Voice), and fingerprint (Fingerprint) and other physiological characteristics . Currently, commercially available fingerprint identification devices are classified into optical, pressure, ultrasonic, and capacitive. As full-screen smartphones gradually become mainstream, off-screen optical fingerprint recognition devices have been widely integrated into full-screen smartphones. FIG. 1 shows a structure diagram of a conventional under-display optical fingerprint recognition device. As shown in Figure 1, the under-screen optical fingerprint identification device is integrated in a smart phone 3a, which mainly includes an image sensing module 11a and a fingerprint identification module 12a, wherein the fingerprint identification module 12a includes a A readout circuit 121a (Readout integrated circuit, ROIC) and an image processing unit 122a, the image sensing module 11a includes a plurality of pixel units, and each pixel unit includes a photosensor 111a and a capacitor 112a .

It is worth noting that currently, a PIN photodiode has been conventionally used as the photosensor 111a. Due to the element characteristics of the PIN photodiode, as long as there is a certain intensity of ambient light, the PIN photodiode (that is, the photosensor 111a) will still absorb photons and then generate a photocurrent to charge the capacitor 112a in the absence of a driving voltage. , so that the capacitor 112a has accumulated charges. In other words, if the pixel unit has accumulated a certain amount of charge before the optical fingerprint collection circuit under the screen performs the fingerprint collection operation, the fingerprint image collected through the fingerprint collection operation will have image retention. This image persistence phenomenon is commonly referred to as strong light afterimage or ghosting (Ghosting). On the other hand, if there are defects in the crystal lattice of the PIN photodiode, these lattice defects will trap electrons under strong light irradiation, thereby forming defect charges. It can be understood that these defect charges will also be converted into photocurrent to charge the capacitor 112a, so that the capacitor 112A contains residual charges.

For example, FIG. 2 is a working stage diagram of the under-display optical fingerprint recognition device shown in FIG. 1, and FIG. 3A is an example diagram of image sensing of the image sensing module 11a shown in FIG. 1 before image acquisition, FIG. 3B is an example diagram of image sensing of the image sensing module 11a shown in FIG. 1 during image acquisition, and FIG. 3C is an image of the image sensing module 11a shown in FIG. 1 after image acquisition Sensing example diagram. As shown in FIG. 2 and FIG. 3A, in the presence of a certain intensity of ambient light, part of the PIN photodiode of the image sensing module 11a (that is, the photosensor 111a) generates a photocurrent pair due to the absorption of photons. The capacitor 112a is charged, causing some pixel units to complete pixel sensing, so that the image sensing module 11a contains a sensing signal corresponding to the first image A1. Further, as shown in FIG. 2 and FIG. 3B, when the under-screen optical fingerprint collection circuit formally executes the fingerprint collection operation, all pixel units complete pixel sensing, so that the image sensing module 11a contains the corresponding second Sensing signal for image A2. As shown in FIG. 2 and FIG. 3C, in the sensing signal readout stage, the readout circuit 121a reads out a sensing signal from the image sensing module 11a, and the image processing unit 122a processes the sensing signal. After a series of signal processing, a collected fingerprint image is obtained. It is worth noting that since there is an overlapping image A21 between the second image A2 and the first image A1, the acquired fingerprint image includes the second image A2 and the overlapping image A21. Image A21 is commonly known as ghosting (Ghosting). Finally, in the fingerprint identification stage, this ghost image becomes the shading pattern of the collected fingerprint image, thereby affecting the fingerprint identification rate.

In order to remove defective charges or residual charges, Chinese Patent Publication No. CN110929645A discloses an image sensing device with the function of removing residual charges, wherein the image sensing device also includes: an image sensing module and an image processing module, wherein the The image processing 12 also includes a readout circuit and an image processing unit. In particular, the readout circuit includes a charge release unit for assisting in clearing the residual charges of the plurality of capacitors of the image sensing module. Usually, the charge releasing unit is directly integrated in the image sensing module. However, practical experience shows that integrating the charge releasing unit in the image sensing module will result in a smaller fill factor, and also reduce the utilization efficiency of the light sensor of the image sensing module.

On the other hand, according to the content disclosed in Chinese Patent Publication No. CN110929645A, the charge release unit can also be integrated in the readout circuit, so that the use efficiency of the light sensor can be optimized and the fill factor of the image sensor module can be improved. . In this case, each of the capacitors 112a may be discharged through the charge releasing unit when performing the residual charge clearing operation. However, in extreme environments such as strong light or low temperature, if no sufficiently high positive voltage is applied to each of the capacitors 112a, the capacitors 112a will still have residual charges after being discharged through the charge releasing unit. In other words, the technical solution taught by the prior art cannot completely remove the glare afterimage.

It can be seen from the above description that there is an urgent need for a strong light afterimage removal circuit in the field.

The main purpose of the present invention is to provide a strong light afterimage removal circuit, which is arranged on a flexible circuit board together with a power management circuit, to work in a strong light afterimage removal stage, so that the power management circuit The transmitted operating voltage is converted into a positive voltage, and the positive voltage is transmitted to a bias voltage terminal of a shadow sensing module including a plurality of pixel units, so that the capacitance contained in each pixel unit is read to a The output circuit is discharged, thereby clearing the residual charge contained in each of the capacitors.

It is worth noting that the image sensing module and the readout circuit are arranged on a substrate, and the strong light afterimage removal circuit of the present invention is arranged on a flexible board coupled to the substrate together with the power management circuit. Therefore, the fill factor of the shadow sensing module will not be affected, and the chip circuit area will not be occupied at the same time.

To achieve the above object, the present invention proposes an embodiment of the strong light afterimage removal circuit, which is applied in an image sensing device including an image sensing module, a readout circuit and a power management circuit , wherein the shadow sample sensing module has a plurality of pixel units sharing a bias voltage terminal, and each of the pixel units includes a light sensor and a capacitor; the strong light afterimage removal circuit includes:

a first electrical terminal coupled to a first output terminal of the power management circuit to receive a first voltage;

a second electrical terminal coupled to a second output terminal of the power management circuit to receive a second voltage greater than the first voltage;

an enabling terminal coupled to an enabling signal;

a third electrical terminal coupled to the bias voltage terminal; and

a charge clearing voltage generating unit, coupled to the first electrical terminal, the second electrical terminal, the enable terminal, and the third electrical terminal;

Wherein, when the enable signal has a high level, the charge clearing voltage generation unit generates a positive voltage to the bias voltage terminal according to the first voltage and the second voltage, thereby driving The capacitance of each pixel unit is discharged to the readout circuit, and the residual charge contained in each capacitance is removed.

In one embodiment, when a first level of the first control signal is greater than a threshold level, the first switching element forms a first channel to couple the first voltage to the current limiting the first end of the resistor.

In one embodiment, after a second level of the second control signal is greater than the threshold level, the second switching element forms a second channel to couple the second voltage to the P-type The source terminal of the MOSFET component.

In one embodiment, the readout circuit includes a gate drive unit and a readout unit, and the readout unit has a charge release unit; when the capacitance of each pixel unit is driven by the positive voltage , the charge releasing unit and the capacitor form a discharge loop, so that the capacitor of each pixel unit is discharged through the discharge loop.

In one embodiment, the power management circuit includes a first DC voltage converter and a second DC voltage converter, the first DC voltage converter generates the first voltage according to an input voltage, and the second DC voltage converter The DC voltage converter generates the second voltage according to the input voltage.

In one embodiment, the readout chip and the image sensing module are arranged on a substrate, and the strong light residual image removal circuit and the power management circuit are arranged together on a substrate having a first end side and a On a flexible printed circuit board at the second end side, the first end side is coupled to the substrate, and an electrical connection interface is provided on the second end side for coupling with a host computer.

In one embodiment, the image sensing module is a passive image sensing module (Passive Pixel Sensor, PPS) or an active pixel sensor (Active Pixel Sensor, APS).

The present invention also proposes an under-display fingerprint identification device, which includes a shadow sensing module, a fingerprint identification chip, and a power management circuit, characterized in that the under-display fingerprint identification device further includes the aforementioned The glare afterimage removal circuit.

The present invention also proposes an image sensing device, including a shadow sensing module, a readout chip, and a power management circuit, characterized in that the image sensing device further includes the strong light of the present invention as described above Afterimage removal circuit.

Moreover, the present invention further proposes an information processing device, which is characterized by having the under-display fingerprint recognition device of the present invention as mentioned above. In a feasible embodiment, the aforementioned information processing device is selected from smart phones, smart watches, smart bracelets, tablet computers, notebook computers, all-in-one computers, financial transaction devices, access control devices, electronic door locks, An electronic device in the group consisting of a fingerprint punching device.

In order to enable your examiners to further understand the structure, features, purpose, and advantages of the present invention, drawings and detailed descriptions of preferred specific embodiments are hereby attached.

Fig. 4 is a schematic perspective view of an under-screen optical fingerprint recognition device including a strong light afterimage removal circuit of the present invention, and Fig. 5 is a front view of a smart phone including the under-screen optical fingerprint recognition device shown in Fig. 4 view. As shown in Figure 5, the under-screen optical fingerprint identification device 1 is integrated in a smart phone 3, which mainly includes an image sensing module 11 and a fingerprint identification module 12, wherein the image sensing module The group 11 has a plurality of pixel units sharing a bias voltage terminal, and each of the pixel units includes a light sensor 111 and a capacitor 112; and the fingerprint identification module 12 includes a readout circuit 121 (Readout integrated circuit, ROIC) and an image processing unit 122.

In terms of practical application, the image sensing module 11 can be a passive image sensing module (Passive Pixel Sensor, PPS) or an active pixel sensor (Active Pixel Sensor, APS). On the other hand, as shown in FIG. 4, the readout circuit 122 and the image sensing module 11 are arranged on a substrate 10, and the strong light afterimage removal circuit 2 and the power management circuit 13 of the present invention are then It is arranged together on a flexible circuit board (FPCB) 14 having a first end side and a second end side, the first end side is coupled to the substrate 10, and the second end side is provided with an electrical connection interface 141 is used for coupling to an application processor (AP) including the image processing unit 122 . Moreover, FIG. 6 is a structural diagram of the under-display fingerprint identification device 1 shown in FIG. 5 . In terms of practical application, the readout circuit 121 includes a gate driving unit 1211 and a readout unit 1212 .

FIG. 7 shows a circuit topology diagram of a strong light afterimage removal circuit of the present invention. As shown in FIG. 4, FIG. 5 and FIG. 7, the power management circuit 13 includes a first DC voltage converter 131 and a second DC voltage converter 132, and the first DC voltage converter 131 is based on an input voltage V _IN A first voltage V _DD1 is generated, and the second DC voltage converter 132 generates a second voltage V _DD2 according to the input voltage VIN. According to the design of the present invention, the strong light afterimage removal circuit 2 includes: a first electrical terminal 2P1, a second electrical terminal 2P2, an enabling terminal 2Pc, a third electrical terminal 2P3, and a charge The clearing voltage generation unit 20, wherein the first electrical terminal 2P1 is coupled to a first output terminal of the power management circuit 13 to receive the first voltage V _DD1 . On the other hand, the second electrical terminal 2P2 is coupled to a second output terminal of the power management circuit 13 to receive the second voltage V _DD2 greater than the first voltage V _DD1 . Moreover, the enable terminal 2Pc is coupled to an enable signal En, and the third electrical terminal 2P3 is coupled to the bias voltage terminal of the image sensing module 11 .

In more detail, the charge clearing voltage generating unit 20 is coupled to the first electrical terminal 2P1, the second electrical terminal 2P2, the enabling terminal 2Pc, and the third electrical terminal 2P3, and includes: a N Type MOSFET element 21 , a P-type MOSFET element 22 , a current limiting resistor R1 , a first switch element 23 , and a second switch element 24 . Wherein, the N-type MOSFET element 21 has a gate terminal, a drain terminal and a source terminal, the gate terminal is coupled to the enable signal En, and the source terminal is coupled to a ground terminal. Moreover, the P-type MOSFET device 22 has a gate terminal, a drain terminal and a source terminal, the gate terminal is coupled to the drain terminal of the N-type MOSFET device 21 , and the drain terminal is coupled to the bias voltage terminal. As shown in FIG. 7, the current limiting resistor R1 has a first end and a second end, and the second end is coupled to the drain end of the N-type MOSFET element 21 and the P-type MOSFET element 22. A first common contact between gate terminals.

According to the above description, the first switch element 23 has a first terminal, a second terminal and a control terminal, the first terminal is coupled to the first voltage V _DD1 , the second terminal is coupled to the current limiting resistor R1 The first terminal and the control terminal are coupled to a first control signal S1. It should be understood that when a first level of the first control signal S1 is greater than a threshold level, the first switching element 23 forms a first channel to couple the first voltage V _DD1 to the The first end of the current limiting resistor R1. On the other hand, the second switch element 24 has a first terminal, a second terminal and a control terminal, the first terminal is coupled to the second voltage V _DD2 , the second terminal is coupled to the P-type MOSFET element 22 The source terminal, and the control terminal is coupled to a second control signal S2. It can also be understood that when a second level of the second control signal S2 is greater than the threshold level, the second switching element 24 forms a second channel to couple the second voltage V _DD2 and to the source terminal of the P-type MOSFET element 22 . Simply put, suitable electronic components can be selected as the second switching element 22 and the first switching element 21, so that an appropriate threshold level (ie, conduction voltage) can be set so that the second switch The element 22 and/or the first switch element 21 are turned on. In a feasible embodiment, both the second switch element 22 and the first switch element 21 can be a P-type MOSFET switch, an N-type MOSFET switch or a CMOS switch.

It is supplemented that, as shown in FIG. 7 , a bridge wire 25 has a first end and a second end, and the first end is coupled to the second end of the first switching element 23 and the current limiting resistor R1 A second common point between the first end of the first end, and the second end is coupled to a first end between the second end of the second switching element 24 and the source end of the P-type MOSFET element 22 Three points of contact.

FIG. 8 is a diagram of the first working stage of the under-display optical fingerprint recognition device shown in FIG. 5 . As shown in FIG. 5 and FIG. 8 , in the exposure stage, the OLED panel of the smart phone 3 emits light to illuminate a finger pressing on a fingerprint collection area. Next, in the fingerprint collection stage, the image sensing module 11 of the under-screen optical fingerprint recognition device 1 receives the reflected light from the finger, so that all pixel units of the image sensing module 11 complete a pixel sensing Operation, at this time the image sensing module 11 contains a sensing signal corresponding to a fingerprint image. As shown in Fig. 5, Fig. 7 and Fig. 8, after the system (that is, the application processor) wakes up the readout circuit (ROIC) 121, the readout circuit 121 is in the All gate on state. At this time, the strong light of the present invention The afterimage removal circuit 2 generates a positive voltage to the bias voltage terminal of the image sensing module 11 . Since a plurality of pixel units share the same bias voltage terminal, this positive voltage can drive the capacitor 112 of each pixel unit to discharge to the readout circuit 121, thereby clearing each capacitor 112 contained residual charge. In this way, in the sensing signal readout phase, the readout circuit 121 reads out a sensing signal from the image sensing module 11, and the image processing unit 122 performs a series of signal processing on the sensing signal Afterwards, a collected fingerprint image that does not contain any strong light afterimage (ie, Ghosting) is obtained. Finally, in the identification stage, the image processing unit 122 completes the fingerprint identification after completing feature matching between the collected fingerprint image and a fingerprint template.

In more detail, as shown in FIG. 7 and FIG. 8 , the strong light afterimage removal operation is performed when the readout circuit 121 is in the All gate on state (ie, in the wake-up phase). At this time, by making the enable signal En have a high potential of, for example, 3V, the N-type MOSFET element 21 is turned on, thereby driving the P-type MOSFET element 22 to be turned on, so that the second voltage V _DD2 passes through the P-type MOSFET The element channel of the element 22 is transmitted to the bias voltage end. In other words, when performing the strong light afterimage removal operation, the second voltage V _DD2 output by the second DC voltage converter 132 is used as the positive voltage to drive the capacitor 112 of each pixel unit to the read voltage. The output circuit 121 is discharged, thereby clearing the residual charge contained in each of the capacitors 112 . It is supplemented that, in terms of practical application, as shown in FIG. 6 and FIG. 7 , the readout unit 1212 may have a charge release unit 121Q. In such a design, when the capacitor 112 of each pixel unit is driven by the positive voltage, the charge releasing unit 121Q can form a discharge circuit with the capacitor 112 so that the capacitor 112 can be discharged through the discharge circuit.

As shown in FIG. 7 and FIG. 8, during the non-working period (that is, the strong light afterimage removal operation is not activated), the N-type MOSFET element 21 is turned off by making the enable signal En have a low potential, thereby driving The P-type MOSFET element 22 is turned off. At this time, the bias voltage terminal is coupled to a bias voltage V _B to drive the light sensor 111 of each pixel unit to receive photons to generate photocurrent.

FIG. 9 is a diagram of the second working stage of the under-display optical fingerprint recognition device shown in FIG. 5 . Electronic engineers who are familiar with the design and manufacture of the readout circuit 121 of the image sensing module 11 must know that, as shown in FIG. Each pixel unit performs a reset operation (usually a row-by-row operation) to clear the charge in the capacitor 112 included in each pixel unit. At this time, the strong light sticking image removal circuit 2 of the present invention can perform the strong light sticking image clearing operation by making the enable signal En have a high potential of, for example, 3V, that is, generate a positive voltage to the image sensor. Measure the bias voltage terminal of the module 11, thereby driving the capacitor 112 of each pixel unit to discharge to the charge release unit 121Q (that is, the discharge circuit) of the readout circuit 121, thereby clearing each capacitor 112 contains the residual charge. It should be known that this residual charge is not only caused by strong ambient light, but may also include the residual charge after the previous readout phase.

It can be seen from Fig. 8 and Fig. 9 that by adjusting the working timing of the enable signal En, the strong light afterimage removal circuit 2 of the present invention can be flexibly controlled to execute the strong light afterimage removal in the wake-up phase or the reset phase operate.

In this way, the above has completely and clearly described a strong light afterimage removal circuit of the present invention; and, through the above, it can be known that the present invention has the following advantages:

(1) The present invention discloses a strong light afterimage removal circuit, which is arranged on a flexible circuit board together with a power management circuit to work in a strong light afterimage removal stage, so that the power management circuit The transmitted operating voltage is converted into a positive voltage, and the positive voltage is transmitted to a bias voltage terminal of a shadow sensing module including a plurality of pixel units, so that the capacitance contained in each pixel unit is sent to a readout The circuit discharges, thereby clearing the residual charge contained in each of said capacitors. It is worth noting that the image sensing module and the readout circuit are arranged on a substrate, and the strong light afterimage removal circuit of the present invention is arranged on a flexible board coupled to the substrate together with the power management circuit. Therefore, the fill factor of the shadow sensing module will not be affected, and the chip circuit area will not be occupied at the same time.

(2) The present invention also provides an under-screen fingerprint recognition device, which includes a shadow sensing module, a fingerprint recognition chip, and a power management circuit, and is characterized in that the under-screen fingerprint recognition device further includes the aforementioned Describe the strong light afterimage removal circuit of the present invention.

(3) The present invention also provides an image sensing device, including a shadow sensing module, a readout chip, and a power management circuit, characterized in that the image sensing device further includes the aforementioned The glare afterimage removal circuit.

(4) The present invention further provides an information processing device, which is characterized by having the under-display fingerprint recognition device of the present invention as described above. In a feasible embodiment, the aforementioned information processing device is selected from smart phones, smart watches, smart bracelets, tablet computers, notebook computers, all-in-one computers, financial transaction devices, access control devices, electronic door locks, An electronic device in the group consisting of a fingerprint punching device.

It must be emphasized that what is disclosed in the above-mentioned case is a preferred embodiment, and all partial changes or modifications derived from the technical ideas of this case and easily deduced by those familiar with the technology are all inseparable from the patent of this case. category of rights.

To sum up, regardless of the purpose, means and efficacy of this case, it shows that it is very different from the conventional technology, and its first invention is practical, and it does meet the patent requirements of the invention. I implore your review committee to understand clearly and grant a patent as soon as possible to benefit you Society is for the Most Prayer.

3a: Smartphone 11a: Image sensing module 111a: Light sensor 112a: capacitance 12a: Fingerprint identification module 121a: readout circuit 122a: Image processing unit 3: Smartphone 10: Substrate 11: Image sensing module 111: Light sensor 112: capacitance 12:Fingerprint identification module 121: readout circuit 1211: Gate drive unit 1212: readout unit 121Q: Charge release unit 122: Image processing unit 13: Power management circuit 131: the first DC voltage converter 132: second DC voltage converter 14: Flexible circuit board 141: electrical connection interface 2: Strong light afterimage removal circuit 2P1: the first electrical terminal 2P2: The second electrical terminal 2P3: The third electrical terminal 2Pc: enable terminal 20: Charge removal voltage generation unit 21: N-type MOSFET components 22: P-type MOSFET components 23: The first switching element 24: Second switching element 25: Bridge wire R1: current limiting resistor

FIG. 1 is a structural diagram of a known under-screen optical fingerprint recognition device; Fig. 2 is a working stage diagram of the under-screen optical fingerprint recognition device shown in Fig. 1; FIG. 3A is an example diagram of image sensing of the image sensing module shown in FIG. 1 before image acquisition; FIG. 3B is an example diagram of image sensing of the image sensing module shown in FIG. 1 during image acquisition; FIG. 3C is an example diagram of image sensing of the image sensing module shown in FIG. 1 after image acquisition; 4 is a schematic perspective view of an under-screen optical fingerprint recognition device including a strong light afterimage removal circuit of the present invention; Fig. 5 is a front view of a smart phone including the under-screen optical fingerprint recognition device shown in Fig. 4; FIG. 6 is a structural diagram of the under-screen fingerprint recognition device 1 shown in FIG. 5; Fig. 7 is a circuit topology diagram of a strong light afterimage removal circuit of the present invention; Fig. 8 is a diagram of the first working stage of the under-screen optical fingerprint recognition device shown in Fig. 5; and FIG. 9 is a diagram of the second working stage of the under-display optical fingerprint recognition device shown in FIG. 5 .

11: Image sensing module

111: Light sensor

112: capacitance

121: readout circuit

121Q: Charge release unit

13: Power management circuit

131: the first DC voltage converter

132: second DC voltage converter

2: Strong light afterimage removal circuit

2P1: the first electrical terminal

2P2: The second electrical terminal

2P3: The third electrical terminal

2Pc: enable terminal

20: Charge removal voltage generation unit

21: N-type MOSFET components

22: P-type MOSFET components

23: The first switching element

24: Second switching element

25: Bridge wire

R1: current limiting resistor

Claims (10)

A strong light afterimage removal circuit 2, which is applied in an image sensing device 1 including an image sensing module 11, a readout circuit 121, and a power management circuit 13, wherein the image sensing module The group 11 has a plurality of pixel units sharing a bias voltage terminal, and each of the pixel units includes a photosensor 111 and a capacitor 112; the strong light afterimage removal circuit 2 includes: a first electrical terminal 2P1, coupled to a first output terminal of the power management circuit 13, thereby receiving a first voltage V _DD1 ; a second electrical terminal 2P2, coupled to a second output terminal of the power management circuit 13, thereby receiving A second voltage V _DD2 greater than the first voltage V _DD1 ; an enabling terminal 2Pc coupled to an enabling signal En; a third electrical terminal 2P3 coupled to the bias voltage terminal; and a charge clearing voltage The generating unit 20 is coupled to the first electrical terminal 2P1, the second electrical terminal 2P2, the enable terminal 2Pc, and the third electrical terminal 2P3; wherein, the enable signal En has a high level In the case of , the charge clearing voltage generating unit 20 generates a positive voltage to the bias voltage terminal according to the first voltage V _DD1 and the second voltage V _DD2 , so as to drive each pixel unit with the positive voltage The capacitor 112 discharges to the readout circuit 121 to remove the residual charge contained in each capacitor 112 . The strong light afterimage removal circuit as described in Claim 1, wherein the charge removal voltage generation unit 20 includes: an N-type MOSFET element 21, having a gate terminal, a drain terminal and a source terminal, and the gate terminal is coupled to The enable signal En, and the source end is coupled to a ground end; a P-type MOSFET element 22 has a gate end, a drain end and a source end, and the gate end is coupled to the N-type MOSFET element 21 a drain terminal, and the drain terminal is coupled to the bias voltage terminal; a current limiting resistor R1 has a first terminal and a second terminal, and the second terminal is coupled to the drain of the N-type MOSFET element 21 a first common point between the terminal terminal and the gate terminal terminal of the P-type MOSFET element 22; a first switch element 23 having a first terminal, a second terminal and a control terminal, the first terminal is coupled to The first voltage V _DD1 , the second terminal is coupled to the first terminal of the current limiting resistor R1, and the control terminal is coupled to a first control signal S1; a second switch element 24 has a first terminal, a second terminal and a control terminal, the first terminal is coupled to the second voltage V _DD2 , the second terminal is coupled to the source terminal of the P-type MOSFET element 22, and the control terminal is coupled to a second control signal S2; and a bridge wire 25 having a first end and a second end, the first end is coupled between the second end of the first switching element 23 and the first end of the current limiting resistor R1 and the second end is coupled to a third common point between the second end of the second switch element 24 and the source terminal of the P-type MOSFET element 22 . The strong light afterimage removal circuit as described in Claim 2, wherein when a first level of the first control signal S1 is greater than a threshold level, the first switching element 23 forms a first channel to The first voltage V _DD1 is coupled to the first end of the current limiting resistor R1 . The strong light afterimage removal circuit according to claim 3, wherein when a second level of the second control signal S2 is greater than the threshold level, the second switching element 24 forms a second channel Such that the second voltage V _DD2 is coupled to the source terminal of the P-type MOSFET element 22 . The strong light afterimage removal circuit as described in Claim 1, wherein the readout circuit 121 includes a gate drive unit 1211 and a readout unit 1212, and the readout unit 1212 has a charge release unit 121Q; When the capacitor 112 of the pixel unit is driven by the positive voltage, the charge releasing unit 121Q and the capacitor 112 form a discharge circuit, so that the capacitor 112 of each pixel unit is discharged through the discharge circuit. The strong light afterimage removal circuit as described in claim 1, wherein the power management circuit 13 includes a first DC voltage converter 131 and a second DC voltage converter 132, and the first DC voltage converter 131 is based on a The input voltage VIN generates the first voltage V _DD1 , and the second DC voltage converter 132 generates the second voltage V _DD2 according to the input voltage VIN. The strong light residual image removal circuit as described in Claim 1, wherein the readout circuit 121 and the image sensing module 11 are arranged on a substrate 10, and the strong light residual image removal circuit 2 and the The power management circuit 13 is disposed together on a flexible circuit board 14 having a first end side and a second end side, the first end side is coupled to the substrate 10, and the second end side is provided with an electrical connection interface 141 is used for coupling a host computer. An off-screen fingerprint recognition device, which includes a shadow sensing module, a fingerprint recognition chip, and a power management circuit, characterized in that the off-screen fingerprint recognition device further includes any A strong light afterimage removal circuit described in one item. An image sensing device, comprising a shadow sensing module, a readout circuit, and a power management circuit, characterized in that the image sensing device further includes any one of claim 1 to claim 7 The strong light afterimage removal circuit described above. An information processing device, characterized by having an under-screen fingerprint recognition device as described in Claim 8.

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