Image sensing device and fingerprint sensing method

Abstract

The present application provides an image sensing device and a fingerprint sensing method. The image sensing device is suitable for being arranged in an electronic device. The image sensing device comprises a light sensor and a controller. The controller is coupled to the light sensor. When the electronic device operates in a sleep mode, the controller operates the light sensor in a light sensing mode. The controller determines whether a signal intensity variation number of a light sensing signal outputted by the light sensor exceeds a preset intensity variation number within a preset time length, to switch the operation of the light sensor in a fingerprint sensing mode. The image sensing device and the fingerprint sensing method of the present application can effectively operate the light sensor, to reduce power consumption.

Description

Technical Field

[0001] This invention relates to a sensing technology, and more particularly to an image sensing device and a fingerprint sensing method. Background Technology

[0002] For existing electronic devices with optical fingerprint sensing capabilities, additional sensing elements, such as capacitive, pressure, or other optical sensors, were previously used as trigger elements to activate the optical fingerprint sensor. Alternatively, the electronic device's system would be immediately woken up and the sensing mechanism would be activated as soon as a similar trigger signal was generated (such as the Face ID sensing mechanism used in Apple iPhones), resulting in frequent false triggers. This not only caused unnecessary power consumption but also caused inconvenience to users. Summary of the Invention

[0003] This invention provides an image sensing device and a fingerprint sensing method that can efficiently operate an optical sensor to reduce power consumption.

[0004] According to an embodiment of the present invention, the image sensing device of the present invention is suitable for installation in an electronic device. The image sensing device includes a light sensor and a controller. The controller is coupled to the light sensor. When the electronic device is operating in a sleep mode, the controller operates the light sensor in a light-sensing mode, and the controller determines whether the number of signal intensity changes of the light-sensing signal output by the light sensor exceeds a preset number of intensity changes within a preset time period, thereby switching the operation of the light sensor to a fingerprint sensing mode.

[0005] According to an embodiment of the present invention, the fingerprint sensing method of the present invention includes the following steps: when the electronic device is operating in a sleep mode, operating the optical sensor in a light-sensing mode; and determining whether the number of signal intensity changes of the light-sensing signal output by the optical sensor exceeds a preset number of intensity changes within a preset time length, so as to switch the operating optical sensor to the fingerprint sensing mode.

[0006] Based on the above, the image sensing device and fingerprint sensing method of the present invention can effectively avoid waking up the electronic device for fingerprint sensing due to accidental touch by the user, and can effectively reduce the power consumption of the electronic device.

[0007] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a circuit diagram of an image sensing device according to an embodiment of the present invention;

[0009] Figure 2 This is a flowchart of a fingerprint sensing method according to an embodiment of the present invention;

[0010] Figure 3 This is a flowchart of the fingerprint sensing method according to the first embodiment of the present invention;

[0011] Figure 4A This is a schematic diagram of the signal intensity change of the photosensitive signal in a dark environment according to the first embodiment of the present invention;

[0012] Figure 4B This is a schematic diagram of the signal intensity change of the photosensitive signal in a bright environment according to the first embodiment of the present invention;

[0013] Figure 5 This is a flowchart of the fingerprint sensing method according to the second embodiment of the present invention;

[0014] Figure 6A This is a schematic diagram of the signal intensity change of the photosensitive signal in a dark environment according to the second embodiment of the present invention;

[0015] Figure 6B This is a schematic diagram of the signal intensity change of the photosensitive signal in a bright environment according to the second embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures

[0017] 100: Electronic devices;

[0018] 110: Image sensing device;

[0019] 111: Controller;

[0020] 112: Optical sensor;

[0021] 120: Processor;

[0022] 130: Light source;

[0023] S1, S2, S1', S2': Photosensitive signals;

[0024] St1, St2, St3: Signal strength thresholds;

[0025] SM, SM': During hibernation;

[0026] LM, LM': During optical communication;

[0027] AM, AM': Illuminance detection period;

[0028] Th1, Th2, Th1', Th2': Preset time length;

[0029] FM, FM': During fingerprint sensing;

[0030] NM, NM': During normal operation;

[0031] t41~t43, t61~t63, t41'~t43', t61'~t63': time;

[0032] S210~S220, S301~S310, S501~S510: Steps. Detailed Implementation

[0033] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same element references are used in the drawings and description to denote the same or similar parts.

[0034] Figure 1 This is a circuit diagram of an image sensing device according to an embodiment of the present invention. (Reference) Figure 1The electronic device 100 includes an image sensing device 110, a processor 120, and a light source 130. The image sensing device 110 includes a controller 111 and a light sensor 112. The controller 111 is coupled to the light sensor 112 and the processor 120. In this embodiment, the electronic device 100 may be a smartphone with fingerprint sensing functionality, but the invention is not limited thereto. The processor 120 may be the central processing unit (CPU) of a smartphone, and the electronic device 100 may also include other functional circuits and memory. In this embodiment, the image sensing device 110 may be an optical fingerprint sensing module integrated into the electronic device 100 to provide fingerprint sensing functionality. In this embodiment, the light source 130 may be an independent illumination source disposed in the electronic device 100 and corresponding to the fingerprint sensing area, such as a light-emitting diode (LED) or a laser light source. Alternatively, in one embodiment, the contact panel of the image sensing device 110 corresponding to the fingerprint sensing area is a glass cover, and the light source 130 can be disposed below the glass cover and located to the side of the fingerprint sensing area, so as to incident illumination light onto the portion of the glass cover corresponding to the fingerprint sensing area by total internal reflection. Alternatively, in another embodiment, the light source 130 can be the display panel of the electronic device 100, such as an organic light-emitting diode (OLED) display panel. In this embodiment, the controller 111 may include, for example, a sensing driving circuit, a fingerprint driving circuit, and related signal processing and functional operation circuits. The light sensor 112 may be, for example, a complementary metal-oxide-semiconductor image sensor (CIS). In one embodiment, the image sensing device 110 can be an under-display fingerprint sensing module, and when the image sensing device 110 performs fingerprint sensing, the electronic device 100 can be activated to illuminate the display panel to provide the illumination light required for fingerprint sensing.

[0035] In this embodiment, the light sensor 112 may include a plurality of sensing pixels arranged in an array. The light sensor 112 can operate in a light-sensing mode or a fingerprint-sensing mode. The light-sensing mode may be a Light Fidelity (Li-Fi) mode or an illuminance detection mode (or ambient light detection mode). In this embodiment, when the light sensor 112 operates in the light-sensing mode, the light sensor 112 can continuously detect changes in the intensity of light signals by means of at least one of the plurality of sensing pixels. The controller 111 may, for example, operate the same (or at least a portion) of sensing pixels of the light sensor 112 for continuous sensing, and monitor whether the number of signal intensity changes of the light-sensing signal of this one (or at least a portion) of sensing pixels exceeds a preset number of intensity changes within a preset time length, so as to determine whether the current user wants to normally operate the electronic device 100 and wake up the processor 120 of the electronic device 100, and perform fingerprint sensing operation for further screen unlocking operation. In response, when the light sensor 112 operates in light-sensing mode, the light sensor 112 can use only one or a portion of the sensing pixels to perform light-sensing operations without activating all the sensing pixels, thereby achieving low-power light-sensing functionality.

[0036] It is worth noting that in the photosensitive mode described in this embodiment, the light source 130 can provide a first illumination light to illuminate the fingerprint sensing area of ​​the finger, so that the light sensor 112 can effectively perform photosensitive operations. Furthermore, in the fingerprint sensing mode described in this embodiment, the light source 130 can provide a second illumination light to illuminate the fingerprint sensing area of ​​the finger, so that the light sensor 112 can effectively acquire the corresponding fingerprint image. The brightness of the first illumination light may be lower than or equal to the brightness of the second illumination light. In one embodiment, the first illumination light may be of low brightness, and the second illumination light may be of normal brightness.

[0037] Figure 2 This is a flowchart of a fingerprint sensing method according to an embodiment of the present invention. (See reference) Figure 1 as well as Figure 2In this embodiment, the image sensing device 110 can execute the following steps S210-S220. In step S210, when the electronic device 100 is operating in sleep mode (or standby mode, screen black mode, or other low-power modes), the controller 111 can operate the light sensor in light-sensing mode. It should be noted that in this embodiment, when the current sensing environment is a bright environment, the controller 111 may not turn on the light source 130. Conversely, when the current sensing environment is a dark environment, the controller 111 may turn on the light source 130. In step S220, the controller 111 can determine whether the number of signal intensity changes of the light-sensing signal output by the light sensor 112 exceeds a preset number of intensity changes within a preset time length, so as to switch the operation of the light sensor 112 in fingerprint sensing mode. In other words, if a user actively and repeatedly covers the light sensor 112 with their finger and then removes it, causing the light-sensitive signal output by the light sensor 112 to undergo signal strength changes exceeding a preset number of intensity changes within a preset time period, the controller 111 determines that the user intends to wake up and use the electronic device 100, and therefore switches the operation of the light sensor 112 to fingerprint sensing mode. Conversely, if the light-sensitive signal output by the light sensor 112 does not undergo signal strength changes exceeding the preset number of intensity changes within a preset time period, the controller 111 determines that the user has accidentally touched the light sensor 112, and will not switch the operation of the light sensor 112 to fingerprint sensing mode, nor will it wake up the processor 120 of the electronic device 100. Therefore, the image sensing device 110 and fingerprint sensing method of this embodiment can effectively avoid unnecessary power consumption of the electronic device 100 due to user accidental touches.

[0038] Figure 3 This is a flowchart of the fingerprint sensing method according to the first embodiment of the present invention. Figure 4A This is a schematic diagram illustrating the signal intensity change of the photosensitized signal in a dark environment according to the first embodiment of the present invention. (Reference) Figure 1 , Figure 3 as well as Figure 4ATaking the photosensitive mode as the optical communication mode and the current sensing environment as a dark environment as an example. In this embodiment, in a dark environment, the image sensing device 110 can perform the following steps S301 to S310. In step S301, the controller 111 can set the signal judgment conditions of the illumination mode. For example, the controller 111 can preset a first signal strength threshold St1 and a second signal strength threshold St2, and for example set a preset number of intensity changes to 2 times and a preset time length Th1. The second signal strength threshold St2 is greater than the first signal strength threshold St1. When the signal strength of the photosensitive signal S1 continuously output by one or a portion of the sensing pixels of the light sensor 112 is greater than the second signal strength threshold St2, it represents the received optical communication value "1". When the signal strength of the photosensitive signal S1 continuously output by one or a portion of the sensing pixels of the light sensor 112 is less than the first signal strength threshold St1, it represents the received optical communication value "0". In step S302, before time t42, the electronic device 100 may operate in sleep mode during sleep period SM, and the controller 111 may operate the light sensor 112 in light communication mode during light communication period LM, so that the light sensor 112 continuously detects changes in light signal intensity by means of at least one of a plurality of sensing pixels and outputs a light-sensitive signal S1.

[0039] In step S303, the light source 130 can decide whether to be illuminated based on whether the current sensing environment is a dark or bright environment. For this purpose, as follows... Figure 4A As shown, since the current sensing environment is dark (the initial signal strength of the photosensitive signal S1 is low), the user can manually turn on the light source 130 by turning on the corresponding hardware switch. Alternatively, the controller 111 can automatically detect that the current sensing environment is dark by using the light sensor 112 or another ambient light sensor, and automatically turn on the light source 130. In step S304, the controller 111 determines whether the signal strength of the photosensitive signal S1 first changes to less than the first signal strength threshold St1, and then changes to greater than the second signal strength threshold St2, in order to count whether the number of signal strength changes of the photosensitive signal S1 exceeds a preset number of intensity changes.

[0040] like Figure 4AAs shown, before time t41, the signal strength of the photosensitive signal S1 may change, but it does not meet the aforementioned signal strength requirement. Therefore, the controller 111 does not perform any other actions and continues to execute S304 to maintain the operation of the light sensor 112 in the optical communication mode. Between time t41 and time t42, the number of signal strength changes (3 times) of the photosensitive signal S1 within a preset time length Th1 exceeds the preset number of signal strength changes (2 times). Therefore, the controller 111 executes step S305. For example, the user's finger is first placed on the light sensor 112, and then quickly pressed on the light sensor 112 3 times, and the optical communication value change is, for example, "0101010". In step S305, between time t42 and time t43, the controller 111 can switch the operation of the light sensor 112 in the fingerprint sensing mode during fingerprint sensing and turn on the light source 130 (providing illumination light to illuminate the sensing target area of ​​the finger) to obtain a fingerprint image (an image of the sensing target area of ​​the finger).

[0041] In this embodiment, between time t42 and time t43, when the controller 111 switches the operating light sensor 112 to fingerprint sensing mode, the controller 111 can output a wake-up signal to the processor 120 of the electronic device 100 to wake up the electronic device 100. The processor 120 of the electronic device 100 can further illuminate the display panel to provide the illumination light required for fingerprint sensing. Then, the controller 111 can provide the fingerprint image to the electronic device 100 so that the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S306, the processor 120 of the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S307, the processor 120 of the electronic device 100 can determine whether the fingerprint verification is successful. If not, the controller 111 can re-execute step S305 to obtain a new fingerprint image again. In one embodiment, if the controller 111 performs fingerprint sensing operations more than a preset number of times, the controller 111 can directly end the fingerprint sensing mode and resume the optical communication mode, and the electronic device 100 can re-enter the sleep mode. If so, the processor 120 of the electronic device 100 determines that the fingerprint image passes fingerprint verification.

[0042] In step S308, after time t43, the processor 120 of the electronic device 100 can perform system operations on the electronic device 100 during normal operation (e.g., entering the operating system screen and executing related system functions). In step S309, the processor 120 of the electronic device 100 can turn off the image sensor 110 and the light source 130, or notify the controller 111 to turn off the light sensor 112. The electronic device 100 can operate in normal mode to perform subsequent operations. Until step S310, the user ends the operation of the electronic device 100, so that the electronic device 100 ends the system operation. After this, the controller 111 can restart S302 to re-detect changes in light signal intensity. Therefore, the image sensor 110 and the fingerprint sensing method of this embodiment can effectively avoid unnecessary power consumption of the electronic device 100 due to accidental touches by the user when the current sensing environment is a dark environment.

[0043] Figure 4B This is a schematic diagram illustrating the signal intensity change of the photosensitized signal in a bright environment according to the first embodiment of the present invention. (Reference) Figure 1 , Figure 3 as well as Figure 4B Taking the light-sensing mode as the optical communication mode and the current sensing environment as a bright environment as an example. In this embodiment, under bright environment, the image sensing device 110 can also perform the following steps S301~S310. In step S301, the controller 111 can set the signal judgment conditions of the illumination mode. For example, the controller 111 can preset a first signal strength threshold St1 and a second signal strength threshold St2, and for example set a preset intensity change number of 2 times and a preset time length Th1'. When the signal strength of the light-sensing signal S1 continuously output by one or a part of the sensing pixels of the light sensor 112 is greater than the second signal strength threshold St2, it represents the received optical communication value "1". When the signal strength of the light-sensing signal S1 continuously output by one or a part of the sensing pixels of the light sensor 112 is less than the first signal strength threshold St1, it represents the received optical communication value "0". In step S302, before time t42, the electronic device 100 may operate in sleep mode during sleep period SM', and the controller 111 may operate the light sensor 112 in light communication mode during light communication period LM', so that the light sensor 112 continuously detects changes in light signal intensity by means of at least one of a plurality of sensing pixels and outputs a light-sensitive signal S1'.

[0044] In step S303, the light source 130 can decide whether to be illuminated based on whether the current sensing environment is a dark or bright environment. For this purpose, as follows... Figure 4BAs shown, since the current sensing environment is a bright environment (the initial signal intensity of the photosensitive signal S1' is relatively high), the light source 130 can be left off initially. In step S304, the controller 111 determines whether the signal intensity of the photosensitive signal S1' first changes to less than the first signal intensity threshold St1, and then changes to greater than the second signal intensity threshold St2, in order to count whether the number of signal intensity changes of the photosensitive signal S1' exceeds a preset number of intensity changes.

[0045] like Figure 4B As shown, before time t41', the signal strength of the photosensitive signal S1' may change, but it does not meet the aforementioned signal strength requirement for the photosensitive signal S1'. Therefore, the controller 111 does not perform any other actions and continues to execute S304 to maintain the operation of the light sensor 112 in the optical communication mode. Between time t41' and time t42', the number of signal strength changes (3 times) of the photosensitive signal S1' within the preset time length Th1' exceeds the preset number of signal strength changes (2 times). Therefore, the controller 111 executes step S305. For example, the user's finger is placed on the light sensor 112 first, and then quickly pressed on the light sensor 112 3 times, and the optical communication value changes, for example, to "1010101". In step S340, between time t42' and time t43', the controller 111 can switch the operating light sensor 112 in fingerprint sensing mode during fingerprint sensing and turn on the light source 130 (providing illumination light to illuminate the sensing target area of ​​the finger) to obtain a fingerprint image (an image of the sensing target area of ​​the finger).

[0046] In this embodiment, between time t42' and time t43', when the controller 111 switches the operating light sensor 112 to fingerprint sensing mode, the controller 111 can output a wake-up signal to the processor 120 of the electronic device 100 to wake up the electronic device 100. The processor 120 of the electronic device 100 can further illuminate the display panel to provide the illumination light required for fingerprint sensing. Then, the controller 111 can provide the fingerprint image to the electronic device 100 so that the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S306, the processor 120 of the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S307, the processor 120 of the electronic device 100 can determine whether the fingerprint verification is successful. If not, the controller 111 can re-execute step S305 to obtain a new fingerprint image again. In one embodiment, if the controller 111 performs fingerprint sensing operations more than a preset number of times, the controller 111 can directly end the fingerprint sensing mode and resume the optical communication mode, and the electronic device 100 can re-enter the sleep mode. If so, the processor 120 of the electronic device 100 determines that the fingerprint image passes fingerprint verification.

[0047] In step S308, after time t43', the processor 120 of the electronic device 100 can perform system operations on the electronic device 100 during normal operation NM (e.g., entering the operating system screen and executing related system functions). In step S309, the processor 120 of the electronic device 100 can turn off the image sensor 110 and the light source 130, or notify the controller 111 to turn off the light sensor 112. The electronic device 100 can operate in normal mode to perform subsequent operations. Until step S310, the user ends the operation of the electronic device 100, so that the electronic device 100 ends the system operation. After this, the controller 111 can restart S302 to re-detect changes in light signal intensity. Therefore, the image sensor 110 and the fingerprint sensing method of this embodiment can effectively avoid unnecessary power consumption of the electronic device 100 due to accidental touches by the user when the current sensing environment is a bright environment.

[0048] Figure 5 This is a flowchart of a fingerprint sensing method according to a second embodiment of the present invention. Figure 6A This is a schematic diagram illustrating the signal intensity change of the photosensitized signal in a dark environment according to the second embodiment of the present invention. (Reference) Figure 1 , Figure 5 as well as Figure 6A Taking the illuminance detection mode as the light-sensing mode and the current sensing environment as a dark environment as an example. In this embodiment, in a dark environment, the image sensing device 110 can perform the following steps S501 to S510. In step S501, the controller 111 can set the signal judgment conditions of the illuminance mode. For example, the controller 111 can preset a third signal intensity threshold St3, and for example set a preset intensity change number of 2 times and a preset time length Th2. When the signal intensity of the light-sensing signal S2 continuously output by one or a portion of the sensing pixels of the light sensor 112 is less than the third signal intensity threshold St3, it indicates that the user's finger is covering the light sensor 112, so that the light sensor 112 is in a state of receiving low illuminance ambient light. When the signal intensity of the light-sensing signal S2' continuously output by one or a portion of the sensing pixels of the light sensor 112 is greater than or equal to the third signal intensity threshold St3, it indicates that the user's finger is not covering the light sensor 112, so that the light sensor 112 is in a state of receiving high illuminance ambient light. In step S502, before time t62, the electronic device 100 may operate in sleep mode during sleep period SM, and the controller 111 may operate the light sensor 112 in illuminance detection mode during illuminance detection period AM, so that the light sensor 112 continuously detects changes in light signal intensity by means of at least one of a plurality of sensing pixels and outputs a light-sensing signal S2.

[0049] In step S503, the light source 130 can decide whether to be illuminated based on whether the current sensing environment is a dark or bright environment. For this reason, as... Figure 6A As shown, since the current sensing environment is dark (the initial signal strength of the photosensitive signal S2 is low), the user can manually turn on the light source 130 by turning on the corresponding hardware switch. Alternatively, the controller 111 can automatically detect that the current sensing environment is dark by using the light sensor 112 or another ambient light sensor, and automatically turn on the light source 130. In step S504, the controller 111 determines whether the signal strength of the photosensitive signal S2 first changes to less than the third signal strength threshold St3, and then changes to greater than the third signal strength threshold St3, in order to count whether the number of signal strength changes of the photosensitive signal S2 exceeds a preset number of intensity changes.

[0050] like Figure 6A As shown, before time t61, the signal strength of the photosensitive signal S2 may change, but it does not meet the aforementioned signal strength requirement. Therefore, the controller 111 does not perform any other actions and continues to execute S504 to maintain the operation of the light sensor 112 in the illumination detection mode. Between time t61 and time t62, the number of signal strength changes (3 times) of the photosensitive signal S2 within the preset time length Th2 exceeds the preset number of intensity changes (2 times). Therefore, the controller 111 executes step S505. For this purpose, the user's finger is placed on the light sensor 112 first, and then quickly pressed on the light sensor 112 3 times. In step S505, between time t62 and time t63, the controller 111 can switch the operation of the light sensor 112 in the fingerprint sensing mode during fingerprint sensing and turn on the light source 130 (providing illumination light to illuminate the sensing target area of ​​the finger) to obtain a fingerprint image (an image of the sensing target area of ​​the finger).

[0051] In this embodiment, between time t62 and time t63, when the controller 111 switches the operating light sensor 112 to fingerprint sensing mode, the controller 111 can output a wake-up signal to the processor 120 of the electronic device 100 to wake up the electronic device 100. The processor 120 of the electronic device 100 can further illuminate the display panel to provide the illumination light required for fingerprint sensing. Then, the controller 111 can provide the fingerprint image to the electronic device 100 so that the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S506, the processor 120 of the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S507, the processor 120 of the electronic device 100 can determine whether the fingerprint verification is successful. If not, the controller 111 can re-execute step S505 to obtain a new fingerprint image again. In one embodiment, if the controller 111 performs fingerprint sensing operations more than a preset number of times, the controller 111 can directly end the fingerprint sensing mode and resume the optical communication mode, and the electronic device 100 can re-enter the sleep mode. If so, the processor 120 of the electronic device 100 determines that the fingerprint image passes fingerprint verification.

[0052] In step S508, after time t63, the processor 120 of the electronic device 100 can perform system operations on the electronic device 100 during normal operation NM (e.g., entering the operating system screen and executing related system functions). In step S509, the processor 120 of the electronic device 100 can turn off the image sensor 110 and the light source 130, or notify the controller 111 to turn off the light sensor 112. The electronic device 100 can operate in normal mode to perform subsequent operations. Until step S510, the user ends the operation of the electronic device 100, so that the electronic device 100 ends the system operation. After this, the controller 111 can restart S502 to re-detect changes in light signal intensity. Therefore, the image sensor 110 and the fingerprint sensing method of this embodiment can effectively avoid unnecessary power consumption of the electronic device 100 due to accidental touches by the user when the current sensing environment is a dark environment.

[0053] Figure 6B This is a schematic diagram illustrating the signal intensity change of the photosensitized signal in a bright environment according to the second embodiment of the present invention. (Reference) Figure 1 , Figure 5 as well as Figure 6BTaking the illuminance detection mode as the light-sensing mode and the current sensing environment as a bright environment as an example. In this embodiment, in a dark environment, the image sensing device 110 can also perform the following steps S501 to S510. In step S501, the controller 111 can set the signal judgment conditions of the illuminance mode. For example, the controller 111 can preset a third signal intensity threshold St3, and for example set a preset number of intensity changes to 2 times and a preset time length Th2'. When the signal intensity of the light-sensing signal S2' continuously output by one or a portion of the sensing pixels of the light sensor 112 is less than the third signal intensity threshold St3, it indicates that the user's finger is covering the light sensor 112, so that the light sensor 112 is in a state of receiving low illuminance ambient light. When the signal intensity of the light-sensing signal S2' continuously output by one or a portion of the sensing pixels of the light sensor 112 is greater than or equal to the third signal intensity threshold St3, it indicates that the user's finger is not covering the light sensor 112, so that the light sensor 112 is in a state of receiving high illuminance ambient light. In step S502, before time t62, the electronic device 100 may operate in sleep mode during sleep period SM, and the controller 111 may operate the light sensor 112 in illuminance detection mode during illuminance detection period AM, so that the light sensor 112 continuously detects changes in light signal intensity by means of at least one of a plurality of sensing pixels and outputs a light-sensing signal S2.

[0054] In step S503, the light source 130 can decide whether to be illuminated based on whether the current sensing environment is a dark or bright environment. For this reason, as... Figure 6B As shown, since the current sensing environment is a bright environment (the initial signal intensity of the photosensitive signal S2' is relatively high), the light source 130 can be left off initially. In step S504, the controller 111 determines whether the signal intensity of the photosensitive signal S2' first changes to less than the third signal intensity threshold St3, and then changes to greater than the third signal intensity threshold St3, in order to count whether the number of signal intensity changes of the photosensitive signal S2' exceeds a preset number of intensity changes.

[0055] like Figure 6AAs shown, before time t61', the signal strength of the photosensitive signal S2' may change, but it does not meet the aforementioned signal strength requirement. Therefore, the controller 111 does not perform any other actions and continues to execute S504 to maintain the operation of the light sensor 112 in the illumination detection mode. Between time t61' and time t62', the number of signal strength changes (3 times) of the photosensitive signal S2' within the preset time length Th2' exceeds the preset number of intensity changes (2 times). Therefore, the controller 111 executes step S505. For this purpose, the user's finger is placed on the light sensor 112 first, and then quickly pressed on the light sensor 112 3 times. In step S505, between time t62' and time t63', the controller 111 can switch the operation of the light sensor 112 in the fingerprint sensing mode during fingerprint sensing (FM') and turn on the light source 130 (providing illumination light to illuminate the sensing target area of ​​the finger) to obtain a fingerprint image (an image of the sensing target area of ​​the finger).

[0056] In this embodiment, between time t62' and time t63', when the controller 111 switches the operating light sensor 112 to fingerprint sensing mode, the controller 111 can output a wake-up signal to the processor 120 of the electronic device 100 to wake up the electronic device 100. The processor 120 of the electronic device 100 can further illuminate the display panel to provide the illumination light required for fingerprint sensing. Then, the controller 111 can provide the fingerprint image to the electronic device 100 so that the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S506, the processor 120 of the electronic device 100 can perform fingerprint verification on the fingerprint image. In step S507, the processor 120 of the electronic device 100 can determine whether the fingerprint verification is successful. If not, the controller 111 can re-execute step S505 to obtain a new fingerprint image again. In one embodiment, if the controller 111 performs fingerprint sensing operations more than a preset number of times, the controller 111 can directly end the fingerprint sensing mode and resume the optical communication mode, and the electronic device 100 can re-enter the sleep mode. If so, the processor 120 of the electronic device 100 determines that the fingerprint image passes fingerprint verification.

[0057] In step S508, after time t63', the processor 120 of the electronic device 100 can perform system operations on the electronic device 100 during normal operation NM (e.g., entering the operating system screen and executing related system functions). In step S509, the processor 120 of the electronic device 100 can turn off the image sensor 110 and the light source 130, or notify the controller 111 to turn off the light sensor 112. The electronic device 100 can operate in normal mode to perform subsequent operations. Until step S510, the user ends the operation of the electronic device 100, so that the electronic device 100 ends the system operation. After this, the controller 111 can restart S502 to re-detect changes in light signal intensity. Therefore, the image sensor 110 and the fingerprint sensing method of this embodiment can effectively avoid unnecessary power consumption of the electronic device 100 due to accidental touches by the user when the current sensing environment is a bright environment.

[0058] In summary, the image sensing device and fingerprint sensing method of the present invention can operate the optical sensor in a low-power light-sensing mode when the electronic device is in sleep mode. Furthermore, the method determines whether to switch the optical sensor to fingerprint sensing mode and wake up the electronic device based on whether the number of signal intensity changes in the light-sensing signal output by the optical sensor exceeds a preset number of intensity changes within a preset time period. Therefore, the image sensing device and fingerprint sensing method of the present invention can effectively prevent the electronic device from being woken up for fingerprint sensing due to accidental user touch and can effectively reduce the power consumption of the electronic device.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An image sensing device adapted to be provided in an electronic device, characterized by, The image sensing device comprises: a light sensor; and a controller coupled to the light sensor, wherein when the electronic device operates in a sleep mode, the controller operates the light sensor in a light sensing mode, and the controller determines whether a number of signal intensity variations of a light sensing signal output by the light sensor exceeds a preset number of intensity variations within a preset time length to switch the light sensor to operate in a fingerprint sensing mode, wherein the controller determines whether the signal intensity of the light sensing signal first varies less than a first signal intensity threshold and then varies greater than a second signal intensity threshold to count the number of signal intensity variations of the light sensing signal, wherein the second signal intensity threshold is greater than the first signal intensity threshold.

2. The image sensing device according to claim 1, wherein When the light sensor operates in the light sensing mode, a light source is determined to be turned on or off to illuminate a finger according to a current sensing environment being a dark state environment or a bright state environment, and when the controller switches the light sensor to operate in the fingerprint sensing mode, the controller outputs a wake-up signal to a processor of the electronic device to wake up the electronic device.

3. The image sensing device according to claim 2, wherein When the electronic device is woken up and the light sensor performs fingerprint sensing, the electronic device synchronously turns on the light source to enable the controller to acquire a fingerprint image of the finger by the light sensor.

4. The image sensing device according to claim 3, wherein The controller provides the fingerprint image to the electronic device to enable the electronic device to perform fingerprint verification on the fingerprint image, and when the fingerprint image passes the fingerprint verification, the electronic device turns off the image sensing device and the light source.

5. The image sensing device according to claim 1, wherein The controller determines whether the signal intensity of the light sensing signal first varies less than a third signal intensity threshold and then varies greater than the third signal intensity threshold to count the number of signal intensity variations of the light sensing signal.

6. The image sensing device according to claim 1, wherein When the light sensor operates in the light sensing mode, the light sensor continuously detects a light signal intensity variation by at least one of a plurality of sensing pixels.

7. The image sensing device according to claim 1, wherein When the light sensor operates in the fingerprint sensing mode, the light sensor performs fingerprint sensing by all of the sensing pixels to acquire a fingerprint image.

8. The image sensing device according to claim 1, wherein The light sensing mode is a light communication mode.

9. The image sensing device according to claim 1, wherein The light sensing mode is an illumination detection mode.

10. A method of fingerprint sensing, characterized by, The method comprises: operating a light sensor in a light sensing mode when an electronic device operates in a sleep mode; and determining whether a number of signal intensity variations of a light sensing signal output by the light sensor exceeds a preset number of intensity variations within a preset time length to switch the light sensor to operate in a fingerprint sensing mode, wherein the step of determining the number of signal intensity variations of the light sensing signal output by the light sensor comprises: determining whether the signal intensity of the light sensing signal first varies less than a first signal intensity threshold and then varies greater than a second signal intensity threshold to count the number of signal intensity variations of the light sensing signal, wherein the second signal intensity threshold is greater than the first signal intensity threshold.

11. The method of sensing a fingerprint according to claim 10, wherein, The method further comprises: when the light sensor operates in the light sensing mode, determining whether a light source is turned on or off to illuminate a finger according to a current sensing environment being a dark state environment or a bright state environment; and ​ outputting a wake-up signal to a processor of the electronic device to wake up the electronic device when the light sensor switches operation to the fingerprint sensing mode.

12. The method of sensing a fingerprint according to claim 11, wherein, Further comprising: synchronously turning on the light source to enable the light sensor to capture a fingerprint image of the finger when the electronic device is woken up and the light sensor is in fingerprint sensing.

13. The method of sensing a fingerprint according to claim 12, wherein, Further comprising: providing the fingerprint image to the electronic device to enable the electronic device to perform fingerprint verification on the fingerprint image; and turning off the light sensor and the light source when the fingerprint image passes the fingerprint verification. The step of determining the number of signal intensity changes of the photosensitive signal output by the light sensor comprises:

14. The method of sensing a fingerprint according to claim 10, wherein, determining the number of signal intensity changes of the photosensitive signal by determining whether the signal intensity of the photosensitive signal first changes by less than a third signal intensity threshold and then changes by more than the third signal intensity threshold. The light sensor continuously detects changes in light signal intensity by at least one of the plurality of sensing pixels when the light sensor operates in the photosensitive mode.

15. The method of sensing a fingerprint according to claim 10, wherein, The light sensor performs fingerprint sensing by all of the sensing pixels to capture a fingerprint image when the light sensor operates in the fingerprint sensing mode.

16. The method of claim 10, wherein, The photosensitive mode is a light communication mode.

17. The method of sensing a fingerprint according to claim 10, wherein, The photosensitive mode is an illuminance detection mode.

18. The method of claim 10, wherein, ​

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