TWI803110B - Image sensing device, fingerprint recognition device and information processing device - Google Patents

Abstract

The present invention mainly discloses an image sensing device, which includes a light sensor array, wherein the light sensor array includes a plurality of light sensing blocks, and each of the light sensing blocks includes a pixel circuit And N light sensors, N is a positive integer of at least 2. According to the design of the present invention, the pixel circuit has N first switch elements respectively coupled to the N light sensors, and the N first switch elements are coupled to a floating diffusion node. Particularly, in the photo-sensing block, an optical layer is arranged on each of the N-1 photo-sensors, and the N-1 photo-sensors have different thicknesses, so that adjacent There is an optical path difference between the two incident lights received by the two light sensors. According to this design, after the image sensing device of the present invention and a fingerprint recognition circuit are integrated into a fingerprint recognition device, the fingerprint recognition circuit can generate a three-dimensional Fingerprint images, thereby increasing the accuracy of fingerprint recognition.

Description

Image sensing device, fingerprint recognition device and information processing device

The invention relates to the technical field of CMOS image sensors, especially an image sensing device that can be used to realize three-dimensional fingerprint collection.

Biometric identification technology is based on the collection of inherent physiological characteristics of the human body as the basis for individual biological identification, such as iris characteristics, facial characteristics, voiceprint characteristics, and fingerprint characteristics. Among various biometric identification technologies, fingerprint identification technology is the most mature, and thus is widely used in various mobile devices in the form of a fingerprint identification circuit. Moreover, with the popularization of mobile payment, using fingerprint recognition to realize identity identification has become an indispensable technology for mobile electronic devices.

Practical experience has shown that it is possible to copy a user's fingerprint left on the glass of a fingerprint reader, use a color printer to print a fake fingerprint image, and then successfully deceive the user's mobile phone with the fake fingerprint image. The fingerprint identification circuit of the device, so as to use fingerprint identification to realize identity identification, successfully unlock the operation right of the mobile electronic device, and then operate the mobile electronic device to perform online financial behavior or mobile payment. Therefore, it is necessary to improve the shortcomings of the known fingerprint identification circuit so that it can simultaneously detect the authenticity of a fingerprint during the fingerprint collection and identification process, so as to improve the security of fingerprint identification.

In view of this, Chinese Invention Patent No. CN109313706B discloses a fingerprint identification device comprising: a photosensor array and a signal processing circuit, wherein the photosensor array includes a plurality of first sensing pixels (ie, light two polar body) and a plurality of second sensing pixels (that is, photodiodes). According to the disclosure of Chinese invention patent number CN109313706B, a color filter layer is arranged on each of the second sensing pixels, so that the plurality of second sensing pixels are used as the plurality of feature pixels. The color filter layer 221 only allows optical signals in a specific wavelength range to pass through, for example, only allows optical signals in the green wavelength band to pass through. According to this design, the reflected light from the finger surface is directly sensed by the first sensing pixel, and is converted into green light by the color filter layer before being sensed by the first sensing pixel. It should be understood that the first photocurrent generated by the first sensing pixel after receiving light and the second photocurrent generated by the second sensing pixel after receiving light will have a photocurrent difference to a certain extent. , the photocurrent difference can be used as the basis for identifying the authenticity of the fingerprint.

Unfortunately, the fingerprint identification device of Chinese invention patent No. CN109313706B can only obtain a 2-dimensional fingerprint image, but cannot obtain a 3-dimensional fingerprint image after fingerprint collection is performed on a fingerprint. Therefore, the conventional fingerprint identification device still has room for improvement in the accuracy of fingerprint identification.

It can be seen from the above description that there is an urgent need in the art for an image sensing device that can be used to realize 3D fingerprint collection.

The main purpose of the present invention is to provide an image sensing device for integrating with a fingerprint identification circuit to form a fingerprint identification device, so that the fingerprint identification device can generate a three-dimensional fingerprint image after fingerprint collection of a fingerprint, thereby way to increase the accuracy of fingerprint recognition.

To achieve the above purpose, the present invention proposes an embodiment of the image sensing device, which includes:

A light sensor array, including a plurality of light sensing blocks, wherein each light sensing block includes a pixel circuit and N light sensors, N is a positive integer of at least 2, the picture The pixel circuit has N first switching elements respectively coupled to the N photosensors, and the N first switching elements are coupled to a floating diffusion node;

Wherein, in each of the photo-sensing blocks, an optical layer is provided on each of the N-1 photo-sensors, and the N-1 optical layers have different thicknesses, so that adjacent There is an optical path difference between the two incident lights received by the two light sensors.

In one embodiment, in the photo-sensing block, each of the N-1 photo sensors is provided with a filter layer, and one photo sensor is provided with a transparent layer. light layer.

In one embodiment, the pixel circuit further includes:

a second switching element, coupled to the floating diffusion node and the N first switching elements;

a third switching element coupled to the floating diffusion node and the N first switching elements; and

A fourth switch element is coupled to the third switch element.

In one embodiment, the image sensing device described in the present invention further includes:

a driving circuit, coupled to the photosensor array, for transmitting a reset signal to a control terminal of each of the second switching elements, and transmitting a transmission signal to a control terminal of each of the first switching elements, and/or transmit a selection signal to a control terminal of each of the fourth switching elements; and

A signal processing circuit, comprising:

A charge integration unit, coupled to an output end of each of the fourth switching elements; wherein, when the reset signal is used to control the on/off of each of the second switching elements, and the transmission signal is used to control each of the first switching elements When a switching element is turned on/off and the selection signal is used to control the on/off of each of the fourth switching elements, the photocurrents of the N photosensors in each of the photo-sensing blocks pass through The output end of the fourth switch element is sent to the charge integration unit, so that the charge integration unit performs charge integration processing on the N photocurrents in stages;

A correlated double sampling unit, coupled to the charge integration unit, is used to receive a charge integration signal transmitted by the charge integration unit in batches, so as to perform a differential process on the charge integration signal according to a reference signal; and

An analog-to-digital conversion unit is coupled to the correlated double-sampling unit, and is used for receiving a sampling signal transmitted by the correlated double-sampling unit in batches, so as to convert the sampling signal into a digital signal.

Moreover, the present invention simultaneously proposes a fingerprint identification device, which includes:

A light sensor array, including a plurality of light sensing blocks, wherein each light sensing block includes a pixel circuit and N light sensors, N is a positive integer of at least 2, the picture The pixel circuit has N first switch elements respectively coupled to the N light sensors, and the N first switch elements are coupled to a floating diffusion node; wherein, between the light sensing blocks wherein, each of the N-1 optical sensors P is provided with an optical layer, and the N-1 optical layers have different thicknesses, so that the light received by two adjacent optical sensors There is an optical path difference between the two incident lights;

A readout circuit, coupled to the photosensor array, for reading out N photocurrent signals in each of the photosensitive blocks, and converting the N photocurrent signals into N digital signals ;as well as

a fingerprint identification unit, coupled to the readout circuit, to perform image processing on each of the digital signals to obtain a collected fingerprint image, and then perform image matching on the collected fingerprint image and a reference fingerprint image to obtain Complete fingerprinting.

In one embodiment, in the photo-sensing block, each of the N-1 photo sensors is provided with a filter layer, and one photo sensor is provided with a transparent layer. light layer.

In one embodiment, the pixel circuit further includes:

a second switching element, coupled to the floating diffusion node and the N first switching elements;

a third switching element coupled to the floating diffusion node and the N first switching elements; and

A fourth switch element is coupled to the third switch element.

In one embodiment, the readout circuit includes:

a driving circuit, coupled to the photosensor array, for transmitting a reset signal to a control terminal of each of the second switching elements, and transmitting a transmission signal to a control terminal of each of the first switching elements, and/or transmit a selection signal to a control terminal of each of the fourth switching elements; and

A signal processing circuit, comprising:

A charge integration unit, coupled to an output end of each of the fourth switching elements; wherein, when the reset signal is used to control the on/off of each of the second switching elements, and the transmission signal is used to control each of the first switching elements When a switching element is turned on/off and the selection signal is used to control the on/off of each of the fourth switching elements, the photocurrents of the N photosensors in each of the photo-sensing blocks pass through The output end of the fourth switch element is sent to the charge integration unit, so that the charge integration unit performs charge integration processing on the N photocurrents in stages;

A correlated double sampling unit, coupled to the charge integration unit, is used to receive a charge integration signal transmitted by the charge integration unit in batches, so as to perform a differential process on the charge integration signal according to a reference signal; and

An analog-to-digital conversion unit is coupled to the correlated double-sampling unit, and is used for receiving a sampling signal transmitted by the correlated double-sampling unit in batches, so as to convert the sampling signal into a digital signal.

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

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.

Image sensing device

The present invention aims to disclose an image sensing device, which can be integrated with a fingerprint recognition circuit to form a fingerprint recognition device, so that the fingerprint recognition device can generate a three-dimensional fingerprint image after fingerprint collection of a fingerprint, thereby increasing The accuracy of fingerprint recognition. FIG. 1 shows a block diagram of an image sensing device of the present invention. As shown in FIG. 1 , the image sensing device 1 of the present invention includes: a photosensor array 11, and a readout circuit (Read-out) including a drive circuit 12, a signal processing circuit 13 and a control unit 14. circuit), wherein the light sensor array 11 includes a plurality of light sensing blocks 111 .

FIG. 2 is a circuit structure diagram of the light sensing block 111 in FIG. 1 . As shown in FIG. 1 and FIG. 2 , each of the light sensing blocks 111 includes a pixel circuit 110 and N light sensors 11P, where N is a positive integer of at least 2, for example, 4. As shown in FIG. In a feasible embodiment, the light sensor 11P may be a photodiode, a CMOS sensor, or a CCD sensor. In more detail, the pixel circuit 110 includes: N first switch elements 11TG respectively coupled to the N light sensors 11P, a second switch element 11RE, a third switch element 11DT, and a first switch element 11DT. Four switching elements 11SE. It can be understood from FIG. 2 that MOSFT elements or TFT elements can be used as the first switch element 11TG, the second switch element 11RE, the third switch element 11DT, and the fourth switch element 11SE. Therefore, the first switching element 11TG, the second switching element 11RE, the third switching element 11DT, and the fourth switching element 11SE are respectively a transfer transistor and a reset transistor. , a driving transistor (Driving transistor), and a selection transistor (Select transistor). Simply put, each of the switching elements has a channel, a first end coupled to one end of the channel (such as a drain/source terminal), and a second terminal coupled to the other end of the channel (such as a source/source terminal). Drain terminal), and a control terminal (such as: gate terminal) for controlling the resistance of the channel.

FIG. 3 is a block diagram of four first switch elements 11TG, four photosensors 11P and a floating diffusion node 11FD in FIG. 2 . As shown in FIG. 2 and FIG. 3 , the first terminals (drain terminals) of the N first switching elements 11TG are simultaneously coupled to a floating diffusion node 11FD and the second terminal (source terminal) of the second switching element 11RE. And the control terminal (gate terminal) of the third switching element 11DT. Moreover, each of the first switching elements 11TG is coupled to a photo sensor 11P (such as a photodiode or a CMOS sensor) with its second terminal, and is coupled to a transmission signal V _Tran with its control terminal. Moreover, the first terminal of the second switching element 11RE is coupled to a working voltage V _DD , and its control terminal is coupled to a reset signal V _RES . On the other hand, the first end of the third switching element 11DT is coupled to the working voltage V _DD , and the second end thereof is coupled to the first end of the fourth switching element 11SE. Moreover, as shown in FIG. 1 and FIG. 2 , the fourth switching element 11SE is coupled to the signal processing circuit 13 with its second terminal coupled as a photocurrent output terminal, and is coupled to a selection signal with its control terminal. V _SEL .

FIG. 4 is a side cross-sectional view of the four photosensors 11P in FIG. 2 . According to the design of the present invention, in each of the photo-sensing blocks 111, N-1 (ie, 3) of the photo-sensors 11P are each provided with an optical layer 110, and the 3 photo-sensors The optical layers 11O have different thicknesses, so that there is an optical path difference between the two incident lights received by two adjacent photosensors 11P. Further, as shown in FIG. 2 and FIG. 4, in the photo-sensing block 111, a filter layer 11F is provided on each of the three photo-sensors 11P, and one of the photo-sensors A light-transmitting layer 11T is disposed on the detector 11P. In one embodiment, the three filter layers 11F are respectively a filter layer 11F for passing only red light, a filter layer 11F for only passing green light, and a filter layer 11F for only passing blue light. Furthermore, as shown in FIG. 2 and FIG. 4 , a light guide layer 11G, such as a lens, is further provided on the filter layer 11F.

As shown in FIG. 1 , FIG. 2 and FIG. 4 , the readout circuit includes: a driving circuit 12 , a signal processing circuit 13 and a control unit 14 , wherein the driving circuit 12 is coupled to the photosensor array 11 . Electronic engineers who are familiar with the design and manufacture of CMOS image sensors should know that the drive circuit 12 transmits a reset signal V _RES to a control terminal of each of the second switching elements 11RE according to the timing control of the control unit 14, A transmission signal V _Tran is sent to a control terminal of each of the first switch elements 11TG, and/or a selection signal V _SEL is sent to a control terminal of each of the fourth switch elements 11SE. For example, as shown in FIG. 2 , when performing signal readout processing on a photo-sensing block 111, a reset signal V _RES is sent to the control terminal of the second switch element 11RE to reset the floating diffusion node. 11FD and the terminal voltages of N (ie, 4) photosensors 11P. Afterwards, as shown in FIG. 2 and FIG. 3 , during a signal readout period, a transmission signal V _Tran is first sent to the control terminal of the first switch element 11TG coupled to the photosensor 11P of the pixel 1, and simultaneously sent A selection signal V _SEL is sent to the control terminal of the fourth switching element 11SE, so that the photocurrent of the photosensor 11P of the pixel 1 passes through the first switching element 11TG, the third switching element 11DT and the fourth switching element 11SE and sent to the charge integration unit 131 . Next, the charge integration unit performs charge integration processing on the photocurrent in stages.

In short, after the terminal voltages of the floating diffusion node 11FD and the N photosensors 11P are reset, after time t1, the channel coupled to the first switching element 11TG of the pixel 1 is formed to allow the readout The circuit collects the pixel 1 (that is, collects the photocurrent of the light sensor 11). Next, let the readout circuit collect pixel 2, pixel 3, and pixel 4 (that is, red pixel, green pixel, and blue pixel) in sequence, and the corresponding charge integration time is t1+Δt, t1+2Δt respectively , t1+3Δt. Afterwards, the correlated double sampling unit 132 receives a charge integration signal transmitted by the charge integration unit 131 in batches, so as to perform a differential process on the charge integration signal according to a reference signal. Finally, the analog-to-digital conversion unit 133 receives a sampling signal transmitted by the correlated double sampling unit 132 in batches, so as to convert the sampling signal into a digital signal.

fingerprint identification device

FIG. 5 shows a block diagram of a fingerprint identification device including the image sensing device 1 shown in FIG. 1 . It should be understood that after the image sensing device 1 and a fingerprint identification unit 15 of the present invention are integrated into a fingerprint identification device 10, the fingerprint identification unit 15 can further perform digital signal transmission from the analog-to-digital conversion unit 133. The signal is processed to generate a three-dimensional fingerprint image. The main reason is that, as shown in FIG. 4 , the material thicknesses of the N optical layers 110 increase (or decrease) sequentially, corresponding to the image distances of different pixels. Therefore, by collecting pixel 1, pixel 2, pixel 3, and pixel 4, pixels with different image distances can be obtained respectively, and then the three-dimensional image of the fingerprint can be obtained through back-end image processing.

Thus, the above has completely and clearly described an image sensing device 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 an image sensing device, which includes a light sensor array, wherein the light sensor array includes a plurality of light sensing blocks, and each of the light sensing blocks includes a A pixel circuit and N light sensors, N is a positive integer of at least 2. According to the design of the present invention, the pixel circuit has N first switch elements respectively coupled to the N light sensors, and the N first switch elements are coupled to a floating diffusion node. Particularly, in the photo-sensing block, an optical layer is arranged on each of the N-1 photo-sensors, and the N-1 photo-sensors have different thicknesses, so that adjacent There is an optical path difference between the two incident lights received by the two light sensors. According to this design, after the image sensing device of the present invention and a fingerprint recognition circuit are integrated into a fingerprint recognition device, the fingerprint recognition circuit can generate a three-dimensional Fingerprint images, thereby increasing the accuracy of fingerprint recognition.

(2) The present invention also provides an information processing device, which is characterized by having the fingerprint identification device of the present invention as described above. In one embodiment, the information processing device is selected from fingerprint punching devices, access control devices, electronic door locks, financial transaction electronic devices, smart phones, tablet computers, notebook computers, all-in-one computers, and smart An electronic device in the group consisting of televisions.

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.

1: Image sensing device

10:Fingerprint identification device

11: Light sensor array

111: Light sensing block

110: Pixel circuit

11P: light sensor

11O: optical layer

11F: filter layer

11T: Translucent layer

11G: light guide layer

11FD: Floating Diffusion Node

11TG: first switching element

11RE: second switching element

11DT: the third switching element

11SE: the fourth switching element

12: Drive circuit

13: Signal processing circuit

131: Charge integration unit

132: Correlated double sampling unit

133: Analog-to-digital conversion unit

14: Control unit

15:Fingerprint identification unit

1 is a block diagram of an image sensing device of the present invention; FIG. 2 is a circuit structure diagram of the light sensing block in FIG. 1; FIG. 3 is four first switching elements, four photosensors and a floating diffusion node in FIG. 2; FIG. 4 is a side cross-sectional view of the four photosensors in FIG. 2; and FIG. 5 is a block diagram of a fingerprint recognition device including the image sensing device shown in FIG. 1 .

111: Light sensing block

11P: light sensor

11FD: Floating Diffusion Node

11TG: first switching element

Claims (10)

An image sensing device, comprising: a light sensor array, including a plurality of light sensing blocks, wherein each light sensing block includes a pixel circuit and N light sensors, and N is at least is a positive integer of 2, the pixel circuit has N first switching elements respectively coupled to the N photosensors, and the N first switching elements are coupled to a floating diffusion node; wherein, in In each of the light-sensing blocks, each of the N-1 light sensors is provided with a light-transmitting layer for optical path adjustment, and each of the N-1 light-path adjusting light-transmitting layers has a different The thickness is such that there is an optical path difference between the two incident lights received by any two horizontally adjacent photosensors, so that the photosensor array provides a three-dimensional fingerprint image. The image sensing device according to claim 1, wherein, in the photo-sensing block, a filter layer is provided on each of the N-1 photo-sensors P, and one of the photo-sensors P A light-transmitting layer is arranged on the light sensor. The image sensing device according to claim 2, wherein the pixel circuit further includes: a second switching element coupled to the floating diffusion node and the N first switching elements; a third switching element coupled to connected to the floating diffusion node and the N first switching elements; and a fourth switching element coupled to the third switching element. The image sensing device as described in claim 3, further comprising: a driving circuit, coupled to the photosensor array, for sending a reset signal to a control terminal of each of the second switching elements, and sending a transmitting a signal to a control terminal of each of the first switching elements, and/or transmitting a selection signal to a control terminal of each of the fourth switching elements; and a signal processing circuit, including: a charge integration unit coupled to To an output terminal of each of the fourth switching elements; wherein, when the reset signal is used to control the on/off of each of the second switching elements, and the transmission signal is used to control the on/off of each of the first switching elements And when using the selection signal to control the opening/closing of each of the fourth switching elements, the photocurrents of the N photosensors in each of the light sensing blocks pass through the fourth switching elements The output terminal of the charge integration unit is transmitted to the charge integration unit, so that the charge integration unit performs charge integration processing on the N photocurrents in batches; a correlated double sampling unit is coupled to the charge integration unit to receive the charge integration unit in batches A charge integration signal transmitted by the charge integration unit, so as to perform a differential process on the charge integration signal according to a reference signal; and an analog-to-digital conversion unit, coupled to the correlated double sampling unit, for receiving the correlated double sampling in batches A sampling signal transmitted by the unit, thereby converting the sampling signal into a digital signal. A fingerprint identification device, comprising: a light sensor array, including a plurality of light sensing blocks, wherein, each of the light sensing blocks includes a pixel circuit and N light sensors, and N is at least is a positive integer of 2, the pixel circuit has N first switching elements respectively coupled to the N photosensors, and the N first switching elements are coupled to a floating diffusion node; wherein, in the Among the photo-sensing blocks, each of the N-1 photosensors is provided with a light-transmitting layer for adjusting the optical distance, and each of the N-1 light-transmitting layers for adjusting the optical distance has a different thickness, so that there is an optical path difference between the two incident lights received by any two horizontally adjacent photosensors; a readout circuit is coupled to the photosensor array for each of the photosensors N photocurrent signals are read out from the photo-sensing block, and the N photocurrent signals are converted into N digital signals; and a fingerprint identification unit is coupled to the readout circuit, so that each of the The digital signal is subjected to image processing to obtain a three-dimensional fingerprint image, and then image matching is performed on the three-dimensional fingerprint image and a reference fingerprint image to complete fingerprint identification. The fingerprint identification device according to claim 5, wherein, in the photo-sensing block, a filter layer is provided on each of the N-1 photo-sensors, and one photo-sensor There is a light-transmitting layer on the detector. The fingerprint identification device according to claim 6, wherein the pixel circuit further includes: a second switching element coupled to the floating diffusion node and the N first switching elements; a third switching element coupled to The floating diffusion node and the N first switching elements; and a fourth switching element coupled to the third switching element. The fingerprint identification device according to claim 7, wherein the readout circuit includes: a driving circuit, coupled to the photosensor array, for transmitting a reset signal to a control terminal of each of the second switching elements, and transmitting a transmission signal to a control terminal of each of the first switching elements, And/or transmit a selection signal to a control terminal of each of the fourth switching elements; and a signal processing circuit, including: a charge integration unit coupled to an output terminal of each of the fourth switching elements; wherein, When the reset signal is used to control the on/off of each of the second switching elements, the transmission signal is used to control the on/off of each of the first switching elements, and the selection signal is used to control the on/off of each of the fourth switching elements. In the case of ON/OFF, the photocurrents of the N photosensors of each photosensitive block are transmitted to the charge integrating unit through the output terminal of the fourth switching element, so that the charge is integrated The unit performs charge integration processing on the N photocurrents in batches; a correlated double sampling unit is coupled to the charge integration unit, and is used to receive a charge integration signal transmitted by the charge integration unit in batches, thereby according to a reference signal performing a differential process on the charge integration signal; and an analog-to-digital conversion unit coupled to the correlated double-sampling unit for receiving a sampling signal transmitted by the correlated double-sampling unit in batches, thereby converting the sampling signal into a digital signal. An information processing device, characterized by having a fingerprint identification device as described in any one of Claim 5 to Claim 8. The information processing device as described in claim 9, which is composed of a fingerprint punching device, an access control device, an electronic door lock, an electronic device for financial transactions, a smart phone, a tablet computer, a notebook computer, an all-in-one computer, and a smart TV An electronic device selected by the formed group.

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