CN211744559U

CN211744559U - Imaging device capable of adjusting pixel size

Info

Publication number: CN211744559U
Application number: CN201922270468.3U
Authority: CN
Inventors: 田建国
Original assignee: Wuhan Xinying Technology Co ltd
Current assignee: Wuhan Xinying Technology Co ltd
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2020-10-23
Anticipated expiration: 2029-12-17

Abstract

The utility model relates to an image device of adjustable pixel size, include: an image sensor and a control circuit coupled to the image sensor; the image sensor includes a plurality of pixel sensors, each pixel sensor including: the light sensing circuit is used for sensing a pixel image formed by irradiating a light source on a visual field plane where an object is positioned, wherein the light sensing circuit has a pixel size in a first direction, and the visual field plane has a visual field size in the first direction; a transparent base layer formed on the photosensitive circuit; and a lens formed on the transparent base layer; the control circuit is used for generating a first control signal for adjusting the pixel size to the control circuit of the image sensor according to the acquired view field size, the acquired image distance and the acquired object distance. The utility model discloses according to field of vision size, image distance and object distance adjustment pixel size, make the pixel image received by photosensitive circuit completely to solve the crosstalk interference problem.

Description

Imaging device capable of adjusting pixel size

Technical Field

The utility model relates to a fingerprint identification technology under the screen especially relates to an image device of adjustable pixel size.

Background

The under screen (under display) fingerprint sensor is a fingerprint sensor integrated under a display screen, and due to the fact that certain intervals are designed among screen pixels, light can be guaranteed to penetrate through. When a user presses the screen by a finger, the screen can emit light to illuminate the finger area, and the reflected light illuminating the fingerprint returns to the sensor array clung to the screen through the gap of the pixels of the screen. Because the fingerprint tissue in the ridge area absorbs light, the light reflected from the ridge becomes dark; the light reflected from the valleys is relatively bright. Therefore, the brightness difference generated by the ridges and the valleys can form a fingerprint pattern on the optical sensor array.

In order to obtain a clear fingerprint pattern, a micro-lens array is disposed between the screen and the optical sensor array to focus the reflected light so that the fingerprint pattern can be imaged on the optical sensor array. However, for different model designs (e.g. different appearance and structure designs of mobile phones), the object distance from the finger to the microlens array and the image distance from the microlens array to the optical sensor array will also change, so the focal length and the pixel size must be adjusted accordingly.

Therefore, how to provide an imaging system with adjustable pixel size has become one of the issues in the art.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the present invention is to provide an image forming apparatus capable of adjusting pixel size in view of the defects in the prior art.

The utility model provides a technical scheme that its technical problem adopted is: an adjustable pixel size imaging device, comprising:

an image sensor and a control circuit coupled to the image sensor;

the image sensor includes a plurality of pixel sensors, each pixel sensor including:

the photosensitive circuit is used for sensing a pixel image formed by irradiating a light source on a visual field plane where an object is located, the photosensitive circuit has a pixel size in a first direction, and the visual field plane has a visual field size in the first direction;

a transparent base layer formed on the photosensitive circuit; and

a lens formed on the transparent base layer, the lens having a focal length in a second direction;

the first direction is the x direction of the plane where the visual field plane is located, and the second direction is the vertical direction of the plane where the visual field plane is located;

the control circuit is used for generating a first control signal for adjusting the pixel size to the image sensor according to the acquired view field size, the image distance and the object distance, so that the pixel image is completely received by the photosensitive circuit.

According to the scheme, the photosensitive circuit comprises a plurality of photosensitive units, an isolation groove is formed between every two photosensitive units, each photosensitive unit comprises a photo-coupling diode used for sensing the image of the pixel, and the pixel size of the photosensitive circuit is equal to the number of the photo-coupling diodes conducted in all the photosensitive units.

According to the scheme, the control circuit comprises a first signal collector for collecting the visual field size, a second signal collector for collecting the image distance, a third signal collector for collecting the object distance, a multiplier circuit and a divider circuit, wherein the first signal collector and the second signal collector are respectively connected with the input end of the multiplier circuit, the output end of the multiplier circuit and the input end of the third signal collector and the input end of the divider circuit are connected, and the output signal of the divider is a first control signal.

According to the above scheme, the photosensitive circuit is provided with a switch coupled to the photosensitive unit and the control circuit, and the switch is used for turning on or off the photo-coupled diode of the photosensitive unit according to the first control signal.

According to the scheme, the photosensitive units in the photosensitive circuit are arranged in a checkerboard manner, the photosensitive circuit comprises n × n photosensitive units, n is a positive odd number, the number of the switches coupled to the photosensitive units and the control circuit is (n +1)/2, the checkerboard-arranged photosensitive units in the photosensitive circuit are divided in a circle, and each switch controls one circle of photosensitive units.

According to above-mentioned scheme, the sensitization unit in the sensitization circuit is the checkerboard arrangement, and sensitization circuit includes n sensitization unit n, and when n equals 3, this sensitization circuit includes:

1 first photosensitive unit;

8 second photosensitive units surrounding the one first photosensitive unit;

16 third light sensing units surrounding the 16 third light sensing units and the one first light sensing unit;

a first switch, coupled to the first photo sensing unit, for turning on or off the photo diode of the first photo sensing unit according to the first control signal;

a second switch, coupled to the 8 second photo-sensing units, for turning on or off the photo-coupling diodes of the 8 second photo-sensing units according to the first control signal; and

a third switch, coupled to the 16 third photo-sensing units, for turning on or off the photo-coupling diodes of the 16 third photo-sensing units according to the first control signal.

According to the scheme, the photosensitive units in the photosensitive circuit are arranged in a checkerboard mode, the photosensitive circuit comprises m photosensitive units, m is a positive even number, the switches coupled to the photosensitive units and the control circuit are m/2 switches, the photosensitive units in the photosensitive circuit are divided into circles, and each switch controls one circle of photosensitive units.

According to above-mentioned scheme, photosensitive unit among the photosensitive circuit is the checkerboard arrangement, and photosensitive circuit includes m photosensitive unit, and when m is 2, this photosensitive circuit includes:

4 first photosensitive units;

12 second photosensitive units surrounding the 4 first photosensitive units;

a first switch, coupled to the 4 first photo-sensing units, for turning on or off the photo-coupling diodes of the 4 first photo-sensing units according to the first control signal; and

and a second switch, coupled to the 12 second photo-sensing units, for turning on or off the photo-coupling diodes of the 12 second photo-sensing units according to the first control signal.

According to the scheme, the photosensitive circuit comprises a plurality of photosensitive units, and the plurality of photosensitive units are arranged in a concentric circle.

According to the proposal, a plurality of photosensitive units in the photosensitive circuit are arranged in concentric circles,

the method comprises the following specific steps:

k annular photosensitive units, wherein an isolation groove is formed between the two photosensitive units, and each photosensitive unit comprises an optical coupling diode used for sensing the pixel image; and

k switches coupled to the light sensing units and the control circuit for turning on or off the photo-coupled diodes of the k light sensing units according to the first control signal;

wherein the pixel size is equal to the number of photo-coupling diodes turned on in the k photo-sensing units, and k is a positive integer.

According to the above scheme, the control circuit further comprises a second control circuit, and the second control circuit generates a second control signal to the imaging device according to the image distance and the object distance to adjust the focal length, so that the object can be clearly imaged on the image pixel.

According to the scheme, the second control circuit comprises a second signal collector for collecting the image distance, a third signal collector for collecting the object distance, three divider circuits and an adder circuit,

the input ends of the first divider and the second divider are 1 and a second signal collector, the input ends of the second divider and the third signal collector are 1 and a third signal collector, the input ends of the first adder are the output ends of the first divider and the second divider, the input ends of the third divider are 1 and the output end of the first adder, and the output end of the third divider is a second control signal.

The second control circuit completes the calculation process as follows:

1/PT+1/DI＝1/f，

where PT is the object distance, DI is the image distance, and f is the focal length.

According to the scheme, the object in the imaging device is a finger, and the pixel image is a fingerprint.

According to the scheme, the lens is a micro liquid crystal lens or an elastic polymer film lens array.

According to the scheme, the object distance is the length of the display panel in the second direction.

According to the scheme, the image distance is the distance from the center of the lens to the bottom surface of the transparent base layer; the object distance is the distance from the center of the lens to the surface of the display panel.

According to the scheme, the object distance is the sum of the distance from the center of the lens to the surface of the display panel and the thickness of the screen pasting film.

According to the scheme, the signal value of the signal collector is obtained through setting or a sensor.

The utility model discloses the beneficial effect who produces is: according to the image sensor, the control circuit generates a control signal to the image sensor to adjust the pixel size according to the view field size, the image distance and the object distance, so that a pixel image is completely received by the photosensitive circuit.

The size of the field of view dimension HFOV depends on the application performance and production costs, the size of the object distance PT depends on the thickness of the display screen, and the size of the image distance DI depends on the strength of the supporting display screen and the requirements of the associated manufacturing process. On the premise of giving the view field size HFOV, the image distance DI and the object distance PT, the pixel size SZ can be adaptively adjusted to solve the crosstalk interference problem. A clear image (e.g., a fingerprint) is acquired.

Drawings

The invention will be further explained with reference to the drawings and examples, wherein:

FIG. 1 is a block diagram of an imaging device according to an embodiment of the present disclosure;

FIG. 2 is a cross-sectional view of an image sensor according to an embodiment of the present application;

FIG. 3 is a top view of a photosensitive circuit according to an embodiment of the present application;

FIG. 4 is a cross-sectional view and a circuit diagram of a photosensitive circuit according to an embodiment of the present disclosure;

FIG. 5 is a top view of another embodiment of the present application;

FIG. 6 is a cross-sectional view and a circuit diagram of another exemplary embodiment of a photosensitive circuit;

FIG. 7 is a top view of another embodiment of the present application;

FIG. 8 is a cross-sectional view and a circuit diagram of another exemplary embodiment of a photosensitive circuit;

in the figure: 1-an imaging device; 10-an image sensor; 12-a control circuit; CTRL1 — a first control signal; CTRL2 — second control signal; HFOV-field size; PT-object distance; DI-image distance; SZ-pixel size; f-focal length; FP-image; 20. 50, 70-photosensitive circuit; 21-a transparent base layer; 22-a lens; 23-a display panel; 301. 302, 303, 501, 502, 701, 702, 703-photoreceptive unit; 304. 504, 704-isolation trenches; A-A ', B-B ', C-C ' -section

SW1, SW2, SW3, SW4, SW5, SW6, SW7, SW 8-switches; x-a first direction; z-a second direction; y-third direction.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.

Fig. 1 is a functional block diagram of an imaging apparatus 1 according to an embodiment of the present application. The imaging device 1 may be an under-screen (i.e. digital) fingerprint sensor, which may be integrated into an electronic device (e.g. tablet computer, smart phone, etc.) for detecting the fingerprint patterns (e.g. ridges and valleys).

The imaging device 1 is used in an electronic device, and includes an image sensor including a plurality of pixel sensors and a control circuit. Each pixel sensor comprises a photosensitive circuit and a control circuit, wherein the photosensitive circuit is used for sensing a pixel image formed by irradiating a light source on a visual field plane where an object is positioned, the photosensitive circuit has a pixel size in a first direction, and the visual field plane has a visual field size in the first direction; a transparent substrate formed on the photosensitive circuit, wherein the length of the transparent substrate in a second direction is an image distance, and the first direction is perpendicular to the second direction; and a lens formed on the transparent substrate and having a focal length in the second direction. The control circuit is coupled to the image sensor and used for generating a first control signal to the image sensor to adjust the pixel size according to the view dimension, the image distance and an object distance of the electronic device, so that the pixel image is completely received by the photosensitive circuit.

In fig. 1, the imaging apparatus 1 includes an image sensor 10 and a control circuit 12. The control circuit 10 is coupled to the image sensor 12 and configured to generate a first control signal CTRL1 to the image sensor 10 to adjust a pixel size SZ according to a field of view dimension HFOV, an image distance DI and an object distance PT. The control circuit 10 is further configured to generate a second control signal CTRL2 to the image sensor 10 to adjust a focal length f according to the image distance DI and the object distance PT. The image sensor 10 is used to generate an image FP, such as a fingerprint.

Fig. 2 is a cross-sectional view of the image sensor 10 in the embodiment of the present application. The image sensor 10 includes a plurality of pixel sensors, each of which includes a photosensitive circuit 20, a transparent substrate 21, and a lens 22. The image sensor 10 can be attached to a display panel 23 of the electronic device.

The photosensitive circuit 20 is used for sensing a pixel image formed by the light source irradiating on a view plane where an object is located, wherein the photosensitive circuit has a pixel size SZ in a first direction X, and the view plane has a view size HFOV in the first direction X. For example, when a user places a finger on the display screen, the light source irradiates the field of view plane where the finger is located to generate a reflected light, and the reflected light is absorbed by the light-sensing circuit 20 to form a pixel image. The pixel images generated by the plurality of light sensing circuits can form an image FP. In one embodiment, the object is a finger and the image FP formed by the pixel images is a fingerprint.

The first direction X and the third direction Y are viewing planes, and the second direction Z is perpendicular to the viewing planes. The common way to establish the XY plane is to use the vertex at the top left corner of the display panel surface (coplanar with the viewing plane) as the origin.

The transparent substrate 21 is formed on the photosensitive circuit 20, and has a length in a second direction Z, which is an image distance DI, and the first direction X is perpendicular to the second direction Z. The lens 22 is formed on the transparent base layer 21, and has a focal length f in the second direction Z. The display panel 23 is formed on the lens 22, and has a length in the second direction Z as an object distance PT. In one embodiment, the display panel 23 is an Organic Light Emitting Diode (OLED) panel, and the lens 22 is a micro liquid crystal lens array (liquid crystal micro lens array) or an elastic polymer film lens array.

As can be seen from the structure of fig. 2, the triangular area formed by the reflected light focused from the field of view dimension HFOV onto the lens 22 is similar to the triangular area formed by the reflected light from the lens 22 onto the pixel dimension SZ. Accordingly, the control circuit 12 determines the pixel size SZ according to a first equation: HFOV (SZ PT)/DI, where HFOV is the field of view size, SZ is the pixel size, PT is the object distance, and DI is the image distance. In one embodiment, when applied to an underscreen fingerprint sensor, the dimension HFOV is 50 microns, the object distance PT is 1.6 millimeters, and the image distance DI is 0.6 millimeters, but is not so limited.

In the present embodiment, the control circuit 12 generates the first control signal to obtain the pixel size, and the control circuit includes: the first signal collector and the second signal collector are respectively connected with the input end of the multiplier circuit, the output end of the multiplier circuit and the input end of the third signal collector are connected with the input end of the divider circuit, and the output end output signal of the divider is a first control signal.

When the sizes of the HFOV, the SZ, the PT and the DI satisfy the first equation, it is ensured that the single pixel image does not exceed the receiving range of the single photo-sensing circuit 20, i.e. the single pixel image is completely received by the single photo-sensing circuit 20. On the contrary, when the single pixel image exceeds the receiving range of the single light sensing circuit 20, it means that the single pixel image may be received by the multiple light sensing circuits 20, and therefore there may be a crosstalk problem between the multiple light sensing circuits 20, resulting in a blurred image FP generated by the image sensor 10. In short, to solve the crosstalk problem, the present application generates a first control signal CTRL1 to the image sensor 10 to adjust the pixel size SZ according to the view dimension HFOV, the image distance DI, and the object distance PT by the control circuit 12, so that the pixel image is completely received by the light sensing circuit 20.

Further, the control circuit 12 determines the focal length f according to a second equation: 1/PT +1/DI is 1/f, where PT is the object distance, DI is the image distance, and f is the focal length. According to the lens imaging principle, when the object distance PT, the image distance DI and the focal length f satisfy the second equation, the object can be clearly imaged on the photosensitive circuit 20, so that the image sensor 10 can generate a clear image FP. In short, to obtain a clear image FP, the present application adjusts the focal length f according to the object distance PT and the image distance DI through the control circuit 12 to ensure that the object is clearly imaged on the photosensitive circuit 20.

In this embodiment, the control circuit 12 generates a second control signal to the imaging device to adjust the focal length, so that the object can be clearly imaged on the image pixel.

The second control circuit for generating the second control signal comprises a second signal collector for collecting the image distance, a third signal collector for collecting the object distance, three divider circuits and an adder circuit,

The photo sensing circuit 20 of the present application includes a plurality of photo diodes (photo diodes), which are turned on or off by a switch to adjust the photo sensing pixel size SZ, for example, the photo diodes are arranged in a concentric circle and a checkerboard arrangement.

With respect to the checkerboard arrangement embodiment, fig. 3 is a top view of the light sensing circuit 20 in the embodiment of the present application. FIG. 4 is a cross-sectional view and a circuit diagram of the light sensing circuit 20 in a cross section A-A' according to the embodiment of the present application. In fig. 3, the light sensing circuit 20 includes n × n light sensing units (e.g.,

light sensing units

301, 302, 303) having an isolation trench 304 formed therebetween, and each light sensing unit includes a photo diode (photo diode) for sensing a pixel image. In fig. 4, the light sensing circuit 20 further includes (n +1)/2 switches (e.g., switches SW1, SW2, SW 3). The switch SW1 is coupled to a photo diode of the light sensing unit 301 and the control circuit 12 (not shown in fig. 4) for turning on or off the photo diode according to a first control signal CRTL 1. The switch SW2 is coupled to the photo diode of the eight light sensing units 302 and the control circuit 12 (not shown in fig. 4) for turning on or off the photo diode according to the first control signal CRTL 1. The switch SW3 is coupled to the photo diode of the sixteen light sensing units 303 and the control circuit 12 (not shown in fig. 4), and is used for turning on or off the photo diode according to the first control signal CRTL 1. In one embodiment, switch SW1 couples the optocoupler diode of photosensing unit 301 to ground to turn off the optocoupler diode of photosensing unit 301; switch SW1 couples the photo-coupled diode of photosensing unit 301 to the output terminal to turn on the photo-coupled diode of photosensing unit 301; the operation of the switches SW2, SW3 may be similar, but not limited to.

As can be seen from the structures in fig. 3 and 4, it is assumed that the light sensing circuit 20 includes n × n light sensing units (n is a positive odd number, and n is 5 in this embodiment, but not limited thereto), among which there are one light sensing unit 301, eight light sensing units 302, and sixteen light sensing units 303. Eight photosensitive units 302 surround one photosensitive unit 301, and sixteen photosensitive units 303 surround the eight photosensitive units 302 and the one photosensitive unit 301. The switch SW1 is used to turn on or off the photo diode of one of the light sensing units 301, the switch SW2 is used to turn on or off the photo diodes of eight of the light sensing units 302, and the switch SW3 is used to turn on or off the photo diodes of sixteen of the light sensing units 303.

In operation, when the first control signal CRTL1 instructs the switches SW1, SW2, SW3 to turn on all photo-coupling diodes of the photo-sensing units 301, 302, 303 (25 photo-coupling diodes are turned on in total), the photo-sensing area of the photo-sensing circuit 20 in the XY plane (the first direction X and the third direction Y) is the largest (corresponding to the maximum pixel size SZ); when the first control signal CRTL1 indicates that the switches SW1 and SW2 turn on the photo-coupling diodes of the light sensing units 301 and 302 and the switch SW3 turns off the photo-coupling diodes of the light sensing unit 303 (totally 9 photo-coupling diodes are turned on), the photo-sensing area of the light sensing circuit 20 in the XY plane can be reduced (corresponding to reduction of the pixel size SZ); when the first control signal CRTL1 indicates that the switch SW1 turns on the photo-coupling diode of the light sensing unit 301 and the switches SW2 and SW3 turn off the photo-coupling diodes of the light sensing units 302 and 303 (1 photo-coupling diode is turned on in total), the minimum photo-sensing area of the light sensing circuit 20 in the XY plane corresponds to the minimum pixel size SZ); and when the first control signal CRTL1 indicates that the switches SW1, SW2 and SW3 turn off the photo diodes of all the photo sensing units 301, 302 and 303, the photo sensing circuit 20 cannot sense the pixel image. In short, the pixel size SZ is equal to the number of photo-coupling diodes conducted in n × n photo-sensing units, and the photo-coupling diodes of the photo-sensing

units

301, 302, 303 are turned on or off by the switches SW1, SW2, SW3, so that the photo-sensing area of the photo-sensing circuit 20 in the XY plane can be adjusted to achieve the purpose of adjusting the pixel size SZ.

With respect to another embodiment of the checkerboard arrangement, FIG. 5 is a top view of the light sensing circuit 50 in an embodiment of the present application. FIG. 6 is a cross-sectional view and a circuit diagram of the light sensing circuit 50 in a cross-section B-B' according to the embodiment of the present application. The photosensitive circuit 20 may be replaced with a photosensitive circuit 50, wherein the pixel size SZ of the photosensitive circuit 20 may be adjusted to n × n (n ═ 1, 3, 5), and the pixel size SZ of the photosensitive circuit 50 may be adjusted to m × m (m ═ 2, 4). The desired pixel size SZ may be selected by one skilled in the art as appropriate, e.g., n may be any positive odd number and m may be any positive even number.

In fig. 5, the light sensing circuit 50 includes m × m light sensing units (e.g., light sensing units 501 and 502) with an isolation trench 504 formed therebetween, and each light sensing unit includes a photo-coupled diode for sensing a pixel image. In FIG. 6, the light sensing circuit 50 also includes m/2 switches (e.g., switches SW4, SW 5). The switch SW4 is coupled to the photo diode of the photo sensing unit 501 and the control circuit 12 (not shown in fig. 6), and is used for turning on or off the photo diode of the four photo sensing units 501 according to the first control signal CRTL 1. The switch SW5 is coupled to the photo diode of the photo sensing unit 502 and the control circuit 12 (not shown in fig. 6), and is used for turning on or off the photo diode of the twelve photo sensing units 502 according to the first control signal CRTL 1. In one embodiment, the switch SW4 connects the photo diode of the light sensing unit 501 to ground to turn off the photo diode of the light sensing unit 501; the switch SW4 couples the photo coupling diode of the light sensing unit 501 to the output terminal to turn on the photo coupling diode of the light sensing unit 501; the operation of switch SW5 may be analogized, but is not limited thereto.

As can be seen from the structures in fig. 5 and 6, it is assumed that the light sensing circuit 50 includes m × m light sensing units (m is a positive even number, and m is 4 in this embodiment, but not limited thereto), among which there are four light sensing units 501 and twelve light sensing units 502. Twelve photosensitive cells 502 surround the four photosensitive cells 501. The switch SW4 is used to turn on or off the photo-coupled diodes of the four photo-sensing units 501, and the switch SW5 is used to turn on or off the photo-coupled diodes of the twelve photo-sensing units 502.

In operation, when the first control signal CRTL1 instructs the switches SW4 and SW5 to turn on all photo-coupling diodes of the photo-sensing units 501 and 502 (16 photo-coupling diodes in total), the photo-sensing area of the photo-sensing circuit 50 in the XY plane (the first direction X and the third direction Y) is the largest (corresponding to the maximum pixel size SZ); when the first control signal CRTL1 indicates that the switch SW4 turns on the photo-coupling diode of the light sensing unit 501 and the switch SW5 turns off the photo-coupling diodes of the light sensing unit 502 (totally turns on 4 photo-coupling diodes), the photo-sensing area of the light sensing circuit 50 in the XY plane can be reduced (corresponding to reduction of the pixel size SZ); and when the first control signal CRTL1 indicates the switches SW4 and SW5 to turn off the photo diodes of all the

photo sensing units

501 and 502, the photo sensing circuit 50 cannot sense the pixel image. In short, the pixel size SZ is equal to the number of photo-coupling diodes conducted in m × m photo-sensing units, and the photo-coupling diodes of the photo-sensing

units

501 and 502 are turned on or off by the switches SW4 and SW5, so that the photo-sensing area of the photo-sensing circuit 50 in the XY plane can be adjusted to achieve the purpose of adjusting the pixel size SZ.

With respect to the embodiment of the concentric circle arrangement, fig. 7 is a top view of the light sensing circuit 70 in the embodiment of the present application. FIG. 8 is a cross-sectional view and a circuit diagram of the light sensing circuit 80 in a cross-section C-C' according to the embodiment of the present application. The light sensing circuit 20 may be replaced with a light sensing circuit 70, wherein the pixel size SZ of the light sensing circuit 70 may be adjusted to k (k ═ 1, 2, 3).

In fig. 7, the light sensing circuit 70 includes k light sensing units (e.g.,

light sensing units

701, 702, 706) having an isolation trench 704 formed therebetween, and each light sensing unit includes a photo-coupled diode for sensing a pixel image. In FIG. 8, the light sensing circuit 70 also includes k switches (e.g., switches SW6, SW7, SW 8). The switch SW6 is coupled to the photo diode of the photo sensing unit 701 and the control circuit 12 (not shown in fig. 8) for turning on or off the photo diode of the photo sensing unit 701 according to the first control signal CRTL 1. The switch SW7 is coupled to the photo diode of the photo sensing unit 702 and the control circuit 12 (not shown in fig. 6) for turning on or off the photo diode of the photo sensing unit 702 according to the first control signal CRTL 1. The switch SW8 is coupled to the photo diode of the light sensing unit 703 and the control circuit 12 (not shown in fig. 6), and is used for turning on or off the photo diode of the light sensing unit 703 according to a first control signal CRTL 1. In one embodiment, switch SW6 couples the photo diode of photo sensing unit 701 to ground to turn off the photo diode of photo sensing unit 701; switch SW7 couples the photo coupling diode of light sensing unit 701 to the output terminal to turn on the photo coupling diode of light sensing unit 701; the operation of the switches SW7, SW8 may be similar, but not limited to.

As can be seen from the structures in fig. 7 and 8, it is assumed that the light sensing circuit 70 includes k light sensing units (k is a positive integer, and k is 3 in this embodiment, but is not limited thereto). The photosensitive unit 701 is circular, the photosensitive unit 702 is annular and surrounds the photosensitive unit 701, and the photosensitive unit 703 is annular and surrounds the photosensitive unit 702.

In operation, when the first control signal CRTL1 instructs the switches SW6, SW7 and SW8 to turn on all photo-coupling diodes of the photo-sensing units 701, 702 and 703 (total to turn on 3 photo-coupling diodes), the photo-sensing area of the photo-sensing circuit 70 in the XY plane (the first direction X and the third direction Y) is the largest (corresponding to the maximum pixel size SZ); when the first control signal CRTL1 instructs the switches SW6 and SW7 to turn on the photo-coupling diodes of the photo-sensing units 701 and 702 and the switch SW8 to turn off the photo-coupling diodes of the photo-sensing unit 703 (2 photo-coupling diodes are turned on in total), the photo-sensing area of the photo-sensing circuit 70 in the XY plane can be reduced (corresponding to reduction of the pixel size SZ); when the first control signal CRTL1 indicates that the switch SW6 turns on the photo-coupling diodes of the photo-sensing units 701 and the switches SW7 and SW8 turn off the photo-coupling diodes of the photo-sensing units 702 and 703 (1 photo-coupling diode is turned on in total), the photo-sensing area of the photo-sensing circuit 70 in the XY plane can be reduced (corresponding to reduction of the pixel size SZ); and when the first control signal CRTL1 indicates that the switches SW6, SW7 and SW8 turn off the photo diodes of all the photo sensing units 701, 702 and 703, the photo sensing circuit 70 cannot sense the pixel image. In short, the pixel size SZ is equal to the number of photo-coupling diodes turned on in the k photo-sensing units, and the photo-coupling diodes of the photo-sensing

units

701, 702, and 703 are turned on or off by the switches SW6, SW7, and SW8, so that the photo-sensing area of the photo-sensing circuit 70 in the XY plane can be adjusted to achieve the purpose of adjusting the pixel size SZ.

Further, considering that screen protection film is generally applied to a display panel of an existing electronic device, the object distance in the control device of the present application is adjusted to the sum of the distance from the center of the lens to the surface of the display panel and the thickness of the screen protection film.

In actual operation, the object distance is obtained by processing the parameters through the image sensor.

Or the object distance is obtained by fine adjustment through selecting the type of the screen film.

To sum up, in order to solve the crosstalk problem, the present application uses the control circuit 12 to generate the first control signal CTRL1 to the image sensor 10 to adjust the pixel size SZ according to the view field size HFOV, the image distance DI, and the object distance PT, so that the pixel image is completely received by the light sensing circuit 20. Further, in order to obtain a clear image FP, the present application adjusts the focal length f according to the object distance PT and the image distance DI through the control circuit 12, so as to ensure that the object is clearly imaged on the

photosensitive circuit

20, 50 or 70. Generally, the size of the field of view dimension HFOV depends on the application performance and production cost, the size of the object distance PT depends on the thickness of the display screen, and the size of the image distance DI depends on the strength of the supporting display screen and the requirements of the associated manufacturing process. With the given view dimension HFOV, image distance DI and object distance PT, the present application can adaptively adjust the pixel dimension SZ and focal distance f to solve the crosstalk problem and obtain a clear image (e.g., fingerprint). Therefore, the imaging device with the adjustable pixel size can be suitable for electronic devices with various specifications, so that the application flexibility is improved.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are considered to be within the scope of the invention as defined by the following claims.

Claims

1. An adjustable pixel size imaging apparatus, comprising:

an image sensor and a control circuit coupled to the image sensor;

a transparent base layer formed on the photosensitive circuit; and

the control circuit is used for generating a first control signal for adjusting the pixel size to the control circuit of the image sensor according to the acquired view field size, the acquired image distance and the acquired object distance.

2. The device as claimed in claim 1, wherein the photosensitive circuit comprises a plurality of photosensitive cells, an isolation trench is formed between every two photosensitive cells, each photosensitive cell comprises a photo diode for sensing the pixel image, and the pixel size of the photosensitive circuit is equal to the number of photo diodes conducted in all the photosensitive cells.

3. The imaging device with the adjustable pixel size according to claim 1, wherein the control circuit comprises a first signal collector for collecting a view field size, a second signal collector for collecting an image distance, a third signal collector for collecting an object distance, a multiplier circuit and a divider circuit, the first signal collector and the second signal collector are respectively connected to an input end of the multiplier circuit, an input end of the multiplier circuit and an input end of the third signal collector are connected to an input end of the divider circuit, and an output end of the divider outputs a first control signal.

4. The device as claimed in claim 1, wherein the photo sensor circuit has a switch coupled to the photo sensor unit and the control circuit for turning on or off the photo diode of the photo sensor unit according to the first control signal.

5. The device as claimed in claim 1, wherein the photosensitive cells of the photosensitive circuit are arranged in a checkerboard pattern, the photosensitive circuit includes n × n photosensitive cells, n is a positive odd number, the number of the switches coupled to the photosensitive cells and the control circuit is (n +1)/2, the checkerboard pattern of the photosensitive cells in the photosensitive circuit is divided into circles, and each switch controls one circle of the photosensitive cells.

6. The device of claim 5, wherein the photosensitive units in the photosensitive circuit are arranged in a checkerboard manner, the photosensitive circuit comprises n × n photosensitive units, and when n is 3, the photosensitive circuit comprises:

1 first photosensitive unit;

8 second photosensitive units surrounding the one first photosensitive unit;

7. The device as claimed in claim 1, wherein the photosensitive cells in the photosensitive circuit are arranged in a checkerboard pattern, the photosensitive circuit includes m photosensitive cells, m is a positive even number, the switches coupled to the photosensitive cells and the control circuit are m/2 switches, and the checkerboard pattern of the photosensitive cells in the photosensitive circuit are divided into circles, each switch controlling one circle of the photosensitive cells.

8. The adjustable pixel size imaging device according to claim 7, wherein the photosensitive units in the photosensitive circuit are arranged in a checkerboard manner, the photosensitive circuit includes m photosensitive units, and when m is 2, the photosensitive circuit includes:

4 first photosensitive units;

12 second photosensitive units surrounding the 4 first photosensitive units;

9. The adjustable pixel size imaging device of claim 1, wherein the photosensitive circuit comprises a plurality of photosensitive cells, the plurality of photosensitive cells being arranged in concentric circles.

10. The adjustable pixel size imaging device of claim 9, wherein the plurality of photosensitive cells in the photosensitive circuit are arranged in concentric circles,

the method comprises the following specific steps:

11. The adjustable pixel size imaging apparatus of claim 1, wherein the control circuit further comprises a second control circuit, the second control circuit generates a second control signal to the imaging apparatus according to the image distance and the object distance to adjust the focal length, so that the object can be clearly imaged on the image pixel.

12. The adjustable pixel size imaging apparatus of claim 11, wherein the second control circuit comprises a second signal collector for collecting an image distance, a third signal collector for collecting an object distance, and three divider circuits and one adder circuit,

13. The adjustable pixel size imaging apparatus of claim 1, wherein the object in the imaging apparatus is a finger and the pixel image is a fingerprint.

14. The adjustable pixel size imaging device of claim 1, wherein the lens is a micro liquid crystal lens or an elastic polymer film lens array.

15. The adjustable pixel size imaging apparatus of claim 1, wherein the image distance is a distance from a center of a lens to a bottom surface of a transparent substrate; the object distance is the distance from the center of the lens to the surface of the display panel.

16. The adjustable pixel size imaging apparatus of claim 1, wherein the object distance is a sum of a distance from a center of the lens to a surface of the display panel and a thickness of the screen paste.