Optical fingerprint sensing device and optical fingerprint sensing method

Abstract

An optical fingerprint sensing device and an optical fingerprint sensing method, the optical fingerprint sensing device comprises a plurality of optical sensing pixels, a plurality of optical blocking pixels and a reading circuit. Each optical sensing pixel comprises a first photodetector for sensing light passing through an optical path, and the optical sensing pixel is used to generate a plurality of sensing signals. Each optical blocking pixel comprises a second photodetector, and light is blocked from entering the second photodetector, and the optical blocking pixel is used to generate a plurality of tracking signals. The reading circuit is used to generate an output signal according to the difference between the sensing signal and the tracking signal. The tracking signal generated above can be used to compensate for the environmental factors contained in the sensing signal, so that fingerprint recognition can be performed with higher accuracy and can be used under various environmental conditions.

Description

Technical Field

[0001] The present disclosure relates to an optical fingerprint sensing module and a display device with optical fingerprint detection. Background Art

[0002] With the development of mobile devices such as smartphones and tablet computers, there is a great demand for personal identification technology. Among various personal identification technologies, fingerprint recognition is considered to be a technology with greater development potential from the perspectives of cost, size and recognition accuracy. On general smartphones, the fingerprint recognition module is usually installed in an area outside the display panel.

[0003] Recently, some smartphones equipped with organic light emitting diode (OLED) panels have integrated fingerprint sensors into the OLED panels to reduce the size of the smartphone's bezel. However, fingerprint sensors are relatively sensitive to environmental conditions (such as temperature changes). When environmental conditions change (for example, when the OLED panel heats up and accumulates heat energy), the sensing data generated by the fingerprint sensor may be biased. Summary of the invention

[0004] One aspect of the present disclosure relates to an optical fingerprint sensing device, which includes a plurality of optical sensing pixels, a plurality of optical blocking pixels, and a reading circuit. The plurality of optical sensing pixels each include a first photodetector for sensing a light passing through a light path, and the plurality of optical sensing pixels are used to generate a plurality of sensing signals. The plurality of optical blocking pixels each include a second photodetector, the light is blocked from entering the second photodetector, and the plurality of optical blocking pixels are used to generate a plurality of tracking signals. The reading circuit is used to generate a plurality of output signals according to the difference between the plurality of sensing signals and the plurality of tracking signals.

[0005] In some embodiments, each of the plurality of optical sensing pixels further includes an optical blocking component, and the light is irradiated to the first photodetector through at least one opening on the optical blocking component.

[0006] In some embodiments, the optical blocking component includes a color filter layer and a light shielding layer. The color filter layer is disposed above the first photodetector, and a first opening along the light path is disposed on the color filter layer. The light shielding layer is disposed above the first photodetector, wherein a second opening along the light path is disposed on the light shielding layer, and the light is irradiated to the first photodetector through the first opening and the second opening.

[0007] In some embodiments, each of the plurality of optical blocking pixels further includes an optical blocking component, and the light is blocked by the optical blocking component from entering the second photodetector.

[0008] In some embodiments, each optical blocking pixel further comprises a first transistor, a second transistor, a third transistor and a capacitor. The gate of the first transistor is coupled to the second photodetector. The second transistor is coupled between the gate of the first transistor and a system voltage level. The third transistor is coupled between the first transistor and a column output line. The capacitor is coupled to the gate of the first transistor.

[0009] In some embodiments, the optical blocking element is configured to cover an area above the second photodetector.

[0010] In some embodiments, the optical blocking element is configured to cover the second photodetector and a region above the first transistor.

[0011] In some embodiments, the optical blocking element is configured to cover the second photodetector, the first transistor, the second transistor, the third transistor, and an area above the capacitor.

[0012] In some embodiments, the readout circuit includes a differential amplifier including a first input terminal and a second input terminal. The first input terminal is used to receive one of the plurality of sensing signals, and the second input terminal is used to receive one of the plurality of tracking signals.

[0013] In some embodiments, the optical sensing pixels and the optical blocking pixels are distributed on a plane including a plurality of blocks, the optical blocking pixels are arranged at the centers of the blocks, and the optical sensing pixels are arranged around the optical blocking pixels.

[0014] In some embodiments, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, the plane comprising a plurality of blocks, a first portion of the plurality of optical blocking pixels being configured at the center of the blocks, a second portion of the plurality of optical blocking pixels being configured at the boundaries of the blocks, and the plurality of optical sensing pixels being configured around the first portion of the plurality of optical blocking pixels.

[0015] In some embodiments, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, the plurality of optical blocking pixels are arranged at a boundary of the plane, and the plurality of optical sensing pixels are arranged in an inner region of the plane.

[0016] In some embodiments, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, and the plurality of optical blocking pixels and the plurality of optical sensing pixels are arranged alternately with each other.

[0017] One aspect of the present disclosure is related to an optical fingerprint sensing method, comprising the following steps: generating a plurality of sensing signals by a plurality of optical sensing pixels, each of the plurality of optical sensing pixels comprising a first photodetector for sensing a light beam passing through a light path; generating a plurality of tracking signals by a plurality of optical blocking pixels, each of the plurality of optical blocking pixels comprising a second photodetector, the light beam being blocked from entering the second photodetector; and generating a plurality of output signals by a differential amplifier according to the difference between the plurality of sensing signals and the plurality of tracking signals.

[0018] In some embodiments, the light sensed by the plurality of sensing signals is used for detecting a fingerprint.

[0019] In some embodiments, the plurality of output signals are compensated based on the plurality of tracking signals.

[0020] In some embodiments, the optical sensing pixels and the optical blocking pixels are distributed on a plane including a plurality of blocks, the optical blocking pixels are arranged at the centers of the blocks, and the optical sensing pixels are arranged around the optical blocking pixels.

[0021] In some embodiments, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, the plane comprising a plurality of blocks, a first portion of the plurality of optical blocking pixels being configured at the center of the blocks, a second portion of the plurality of optical blocking pixels being configured at the boundaries of the blocks, and the plurality of optical sensing pixels being configured around the first portion of the plurality of optical blocking pixels.

[0022] In some embodiments, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, the plurality of optical blocking pixels are arranged at a boundary of the plane, and the plurality of optical sensing pixels are arranged in an inner region of the plane.

[0023] In some embodiments, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, and the plurality of optical blocking pixels and the plurality of optical sensing pixels are arranged alternately with each other.

[0024] In some embodiments, the output signal generated by the above-mentioned optical fingerprint sensing device and method will not be affected by environmental factors (such as temperature changes) because the tracking signal can be used to compensate for the environmental factors contained in the sensing signal. In this way, fingerprint recognition can achieve higher accuracy and can be used under various environmental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of an optical fingerprint sensing device according to some embodiments of the present disclosure is shown;

[0026] Figure 2 Some embodiments of the present disclosure are shown in FIG. Figure 1 A cross-sectional view of the layered structure of an optical sensing pixel;

[0027] Figure 3 Some embodiments of the present disclosure are shown in FIG. Figure 1 Cross-sectional view of the layered structure of an optical blocking pixel in FIG.

[0028] Figure 4A Some embodiments of the present disclosure are shown in FIG. Figure 1 A schematic diagram of a circuit architecture of an optical sensing pixel in FIG.

[0029] Figure 4B In some other embodiments of the present disclosure, Figure 1 A schematic diagram of a circuit architecture of an optical sensing pixel in FIG.

[0030] Figure 5A Some embodiments of the present disclosure are shown in FIG. Figure 1 A schematic diagram of a circuit architecture of an optical blocking pixel in FIG.

[0031] Figure 5B In some other embodiments of the present disclosure, Figure 1 A schematic diagram of a circuit architecture of an optical blocking pixel in FIG.

[0032] Figure 5C In some other embodiments of the present disclosure, Figure 1 A schematic diagram of a circuit architecture of an optical blocking pixel in FIG.

[0033] Figure 6 A schematic diagram illustrating the relationship between one of a plurality of optical sensing pixels, one of a plurality of optical blocking pixels, and a readout circuit in some embodiments of the present disclosure is shown;

[0034] Fig. 7A A schematic diagram illustrating a plurality of optical sensing pixels and a plurality of optical blocking pixels according to some embodiments of the present disclosure is shown;

[0035] Figure 7B Schematic diagrams showing a plurality of optical sensing pixels and a plurality of optical blocking pixels according to some other embodiments of the present disclosure;

[0036] Figure 7CSchematic diagrams showing a plurality of optical sensing pixels and a plurality of optical blocking pixels according to some other embodiments of the present disclosure;

[0037] Fig.7D Schematic diagrams showing a plurality of optical sensing pixels and a plurality of optical blocking pixels according to some other embodiments of the present disclosure;

[0038] Figure 8 A flowchart of an optical fingerprint sensing method according to some embodiments of the present disclosure is shown.

[0039]

Explanation of symbols

[0040] 100, 100a~100d: Optical fingerprint sensing device

[0041] 120: Optical sensing pixels

[0042] 140: Optical blocking pixels

[0043] 150: Select circuit

[0044] 160: Reading circuit

[0045] 162: Differential Amplifier

[0046] 164:Analog-to-digital converter

[0047] SIN: Sense signal

[0048] TR:Tracking Signal

[0049] DIF: Difference

[0050] IN1: First input terminal

[0051] IN2: Second input terminal

[0052] OA: Analog output signal

[0053] OUT: Output signal

[0054] BLK, BLKa, BLKb, BLKc: Optical barrier components

[0055] ILL: Light

[0056] L1: Backlight layer

[0057] L2, L9: Polarizing layer

[0058] L3, L8: Glass layer

[0059] PD1: First Photodetector

[0060] L4: Light-shielding layer

[0061] L5: Auxiliary layer

[0062] L6: Liquid crystal layer

[0063] L7: Color filter layer

[0064] T1: First transistor

[0065] T2: Second transistor

[0066] T3: The third transistor

[0067] T4: The fourth transistor

[0068] C1, CHS, CHR: Capacitor

[0069] VDD: System voltage level

[0070] SEL: Select signal

[0071] RES: reset signal

[0072] OCL: Column Output Line

[0073] SHR: control signal

[0074] VB1: Bias control signal

[0075] TB,Ts1,Ts2: Transistor

[0076] Z1, Z2, Z3: Blocks

[0077] 200:Optical fingerprint sensing method

[0078] S210, S220, S230: Steps DETAILED DESCRIPTION

[0079] The following will disclose embodiments and drawings for implementation. For clarity, many implementation details are explained in the following description. However, it will be understood that these details of the practice are not intended to limit the present disclosure. That is, these details of the practice are not necessary for the part of the embodiments of the present disclosure. Moreover, in order to simplify the drawings, some conventional structures and elements are shown with schematic illustrations.

[0080] According to one aspect of the present disclosure, an optical fingerprint sensing device is provided, which can detect or sense the fingerprint of a user's finger. In various embodiments, the optical fingerprint sensing device can detect light reflected by the finger, thereby detecting the fingerprint.

[0081] Figure 1 is a schematic diagram of an optical fingerprint sensing device 100 according to some embodiments of the present disclosure. Figure 1As shown, the optical fingerprint sensing device 100 includes a plurality of optical sensing pixels 120, a plurality of optical blocking pixels 140, a switch circuit 150, and a reading circuit 160. The plurality of optical sensing pixels 120 are used to generate a plurality of sensing signals SIN, and the plurality of sensing signals SIN are used to represent the light intensity distribution obtained when detecting fingerprints. The plurality of optical blocking pixels 140 are used to generate a plurality of tracking signals TR, and the plurality of tracking signals TR are used to track environmental conditions related to the optical sensing pixels 120 (e.g., temperature deviation, signal transmission deviation). The switch circuit 150 is coupled between the plurality of optical sensing pixels 120, the plurality of optical blocking pixels 140, and the reading circuit 160. The reading circuit 160 is used to generate an output signal OUT according to the difference DIF between the plurality of sensing signals SIN and the plurality of tracking signals TR.

[0082] like Figure 1 As shown, in some embodiments, the readout circuit 160 includes a differential amplifier 162 and an analog-to-digital converter (ADC) 164. The differential amplifier 162 includes a first input terminal IN1 and a second input terminal IN2. The first input terminal IN1 is used to receive one of a plurality of sensing signals SIN, and the second input terminal IN2 is used to receive one of a plurality of tracking signals TR.

[0083] In order to generate an output signal OUT corresponding to one of the optical sensing pixels 120, the switch circuit 150 is used to select one of the sensing signals SIN generated by one of the optical sensing pixels 120 at a time point, and transmit the selected sensing signal SIN to the first input terminal IN1 of the differential amplifier 162. At the same time, the switch circuit 150 is used to select a corresponding tracking signal TR generated by a corresponding one of the optical blocking pixels 140, and transmit the selected tracking signal TR to the second input terminal IN2 of the differential amplifier 162. The differential amplifier 162 is used to generate an output signal OUT according to the difference DIF between the selected sensing signal SIN and the selected tracking signal TR to generate an analog output signal OA. The analog-to-digital converter 164 converts the analog output signal OA into an output signal OUT. In some embodiments, the optical fingerprint sensing device 100 repeatedly performs the above operation to generate the output signals OUT corresponding to each of the plurality of optical sensing pixels 120 one by one.

[0084] Please also read Figure 2 as well as Figure 3 , Figure 2 Some embodiments of the present disclosure are shown in FIG. Figure 1 FIG. 1 is a cross-sectional view of a layered structure of an optical sensing pixel 120 . Figure 3 Some embodiments of the present disclosure are shown in FIG. Figure 1FIG. 1 is a cross-sectional view of the layered structure of an optical blocking pixel 140.

[0085] like Figure 2 As shown, each of the optical sensing pixels 120 includes a first photodetector (photodevice) PD1. The first photodetector PD1 is used to sense the light ILL passing through the optical path OP. In some embodiments, the light ILL can be reflected light reflected from a fingerprint in contact with the optical sensing pixel 120. According to the intensity level of the light ILL received by the first photodetector PD1, the optical sensing pixel 120 can generate the aforementioned sensing signal SIN. For example, when the intensity of the light ILL received by the first photodetector PD1 is higher, the current amplitude or voltage level of the sensing signal SIN is higher. In some embodiments, the first photodetector PD1 includes a photodiode for sensing the above-mentioned light ILL.

[0086] It should be noted that, ideally, the sensing signal SIN is substantially determined by the intensity level of the light ILL. In actual situations, the sensing signal SIN generated by the optical sensing pixel 120 is also affected by the environmental conditions (e.g., temperature changes) around the optical sensing pixel 120. For example, when the ambient temperature around the optical sensing pixel 120 becomes high (e.g., the optical sensing pixel 120 generates a large current, or a large current flows through the optical sensing pixel 120), the sensing signal SIN will be offset and distorted.

[0087] like Figure 2 As shown, in some embodiments, the optical sensing pixel 120 can be implemented by a multi-layer structure, including a backlight layer L1, a polarizing layer L2, a glass layer L3, a first photodetector PD1, a shading layer L4, an auxiliary layer L5, a liquid crystal layer L6, a color filter layer L7, another glass layer L8 and another polarizing layer L9. Figure 2 The layered structure of the optical sensing pixels 120 shown is only used as an illustrative example for illustration, and the optical sensing pixels 120 in the present disclosure are not limited to having the same layering or the same arrangement order. Figure 2 As shown, the optical sensing pixel 120 has an optical blocking element BLK including a color filter layer L7 and a light shielding layer L4. Light ILL passes through at least one opening (such as openings O1 and O2) on the optical blocking element BLK and reaches the first photodetector PD1. In some embodiments, the light shielding layer L4 can be implemented using a metal layer.

[0088] exist Figure 2In the illustrated optical sensing pixel 120, the color filter layer L7 is disposed above the first photodetector PD1, and the color filter layer L7 has a first opening O1 along the optical path OP. The light shielding layer L4 is also disposed above the first photodetector PD1, and the light shielding layer L4 has a second opening O2 along the optical path OP. The light ILL passes through the first opening O1 of the color filter layer L7 and the second opening O2 of the light shielding layer L4 to reach the first photodetector PD1, so that the first photodetector PD1 can sense the light ILL entering from the upper surface of the optical sensing pixel 120.

[0089] On the other hand, Figure 3 As shown, each of the optical blocking pixels 140 includes a second photodetector PD2, and the light ILL is blocked from entering the second photodetector PD2. In other words, the signal generated by the second photodetector PD2 will not be affected by the light ILL, and the signal generated by the second photodetector PD2 will be affected by the environmental conditions (such as temperature changes) around the optical blocking pixel 140. Depending on the environmental conditions, the optical blocking pixel 140 can generate a corresponding tracking signal TR. For example, when the ambient temperature is high, the current amplitude or voltage level of the tracking signal TR is lower. In some embodiments, the second photodetector PD2 includes a photodiode, which is used as a dummy photodiode to track the environmental conditions.

[0090] like Figure 3 As shown, in some embodiments, the optical blocking pixel 140 can be realized by a multi-layer structure, including a backlight layer L1, a polarizing layer L2, a glass layer L3, a first photodetector PD1, a shading layer L4, an auxiliary layer L5, a liquid crystal layer L6, a color filter layer L7, another glass layer L8 and another polarizing layer L9. Figure 3 The layered structure of the optical blocking pixels 140 shown is only used as an illustrative example for illustration, and the optical blocking pixels 140 in the present disclosure are not limited to having the same layering or the same arrangement order. Figure 3 As shown, the optical blocking pixel 140 has an optical blocking element BLK including a color filter layer L7 and a light shielding layer L4. The light ILL is blocked by the optical blocking element BLK (ie, the color filter layer L7 and the light shielding layer L4) and does not irradiate the second photodetector PD2.

[0091] Figure 3 The optical blocking pixel 140 and Figure 2 The optical sensing pixel 120 in FIG. 1 has a similar structure. Figure 2 and Figure 3In the embodiment of the present invention, the difference between the optical blocking pixel 140 and the optical sensing pixel 120 is that the optical blocking element BLK in the optical blocking pixel 140 does not have an opening.

[0092] Please also read Figure 4A , which illustrates some embodiments according to the present disclosure Figure 1 FIG. 1 is a schematic diagram of a circuit structure of an optical sensing pixel 120. Figure 4A As shown, the optical sensing pixel 120 includes a first photodetector PD1, three transistors (a first transistor T1, a second transistor T2 and a third transistor T3) and a capacitor C1. In other words, Figure 4A The circuit structure of the optical sensing pixel 120 shown therein is three transistors and one capacitor (3T1C).

[0093] The gate of the first transistor T1 is coupled to the first photodetector PD1. The two source / drain terminals of the first transistor T1 are respectively coupled to a system voltage potential VDD and the third transistor T3. The gate of the second transistor T2 receives a reset signal RES. The two source / drain terminals of the second transistor T2 are respectively coupled to the system voltage potential VDD and the first transistor T1. The gate of the third transistor T3 receives a selection signal SEL. The two source / drain terminals of the third transistor T3 are respectively coupled between the first transistor T1 and the column output line OCL. One end of the capacitor C1 is coupled to the gate of the source follower transistor. The capacitor C1 can be implemented by a floating diffusion (FD) layer. According to the intensity level of the light ILL received by the first photodetector PD1, the voltage level of the node N1 is charged (and maintained by the capacitor C1). When the third transistor T3 is activated by the selection signal SEL, the first transistor T1 is driven by the voltage level on the node N1 to generate the sensing signal SIN. In some embodiments, another transistor TB is driven by a bias control signal VB1 to provide a bias voltage to the sensing signal SIN. When another transistor Ts1 is activated by the control signal SHS, the sensing signal SIN is transmitted to the column output line OCL and temporarily stored in another capacitor CHS. When the selection circuit 150 selects this column output line OCL, the sensing signal SIN is transmitted to the differential amplifier 162 (see Figure 1 ) of the first input terminal IN1. In some embodiments, the sensing signal SIN generated by the optical sensing pixel 120 is determined according to at least two factors, including an optical sensing factor related to the light ILL (see Figure 2 ) and environmental factors related to environmental conditions. This is because in addition to the light ILL, environmental factors may also affect the voltage level on the node N1 or the current passing through the first transistor T1.

[0094] Please also read Figure 4B , which illustrates some embodiments according to the present disclosure Figure 1 Another circuit structure diagram of the optical sensing pixel 120 is shown in FIG. Figure 4B As shown, the optical sensing pixel 120 includes a first photodetector PD1, four transistors (a first transistor T1, a second transistor T2, a third transistor T3 and a fourth transistor T4) and a capacitor C1. In other words, Figure 4B The circuit structure of the optical sensing pixel 120 shown therein is four transistors and one capacitor (4T1C). Figure 4A The illustrated embodiment, Figure 4B The optical sensing pixel 120 further includes a fourth transistor T4, which is coupled between the first photodetector PD1 and the node N1. The gate of the fourth transistor T4 is controlled by a gate transfer control signal TG. Figure 4A The three transistors are paired with a capacitor (3T1C) and Figure 4B The four transistors and one capacitor (4T1C) are merely an illustrative example for implementing the optical sensing pixel 120 , but the present disclosure is not limited thereto.

[0095] Please also read Figure 5A , which illustrates some embodiments according to the present disclosure Figure 1 A schematic diagram of a circuit structure of the optical blocking pixel 140 in FIG. Figure 5A As shown, the optical blocking pixel 140 includes a second photodetector PD2, three transistors (a first transistor T1, a second transistor T2 and a third transistor T3) and a capacitor C1. In other words, Figure 5A The circuit structure of the optical blocking pixel 140 shown therein is three transistors and one capacitor (3T1C).

[0096] Figure 5A The circuit structure of the optical blocking pixel 140 is similar to Figure 4A The optical sensing pixel 120 in the optical blocking pixel 140. The functions and operation of the three transistors and one capacitor (3T1C) in the optical blocking pixel 140 are similar to those of the optical sensing pixel 120 in the previous embodiment. The optical blocking pixel 140 is used to generate a tracking signal TR. When another transistor Ts2 is activated by the control signal SHR, the tracking signal TR is transmitted to the column output line OCL and temporarily stored in another capacitor CHR. When the selection circuit 150 selects this column output line OCL, the tracking signal TR is transmitted to the differential amplifier 162 (see Figure 1 )'s second input terminal IN2.

[0097] It should be noted that Figure 5AThe optical blocking pixel 140 further includes an optical blocking element BLKa, which is configured to cover the area above the second photodetector PD2. The optical blocking element BLKa is used to block light from irradiating the second photodetector PD2. In this example, the tracking signal TR is determined based on environmental factors related to environmental conditions, and the tracking signal TR is not affected by optical sensing factors related to light. Therefore, in some embodiments, the tracking signal TR can be used to track the environmental conditions around the optical blocking pixel 140.

[0098] exist Figure 5A The optical blocking element BLKa is configured to cover the area above the second photodetector PD2, but the present disclosure is not limited thereto. In some other embodiments, the optical blocking element may cover more areas of the optical blocking pixel 140 to ensure that the optical blocking pixel 140 is not affected by optical sensing factors. Figure 5B , which illustrates some embodiments according to the present disclosure Figure 1 FIG. 1 is a schematic diagram of another circuit structure of the optical blocking pixel 140 in FIG. Figure 5B The optical blocking pixel 140 includes an optical blocking element BLKb, which is configured to cover the area above the second photodetector PD2, the first transistor T1, the second transistor T2, the third transistor T3, and the capacitor C1. In this example, the optical sensing factor will not affect the operation of the second photodetector PD2, the first transistor T1, the second transistor T2, the third transistor T3, and the capacitor C1.

[0099] Please also read Figure 5C , which illustrates some embodiments according to the present disclosure Figure 1 FIG. 1 is a schematic diagram of another circuit structure of the optical blocking pixel 140 in FIG. Figure 5C The optical blocking pixel 140 includes an optical blocking element BLKc, and the optical blocking element BLKc is configured to cover the second photodetector PD2 and the area above the first transistor T1. In this example, the optical sensing factor will not affect the operation of the second photodetector PD2 and the first transistor T1.

[0100] In the above FIG. 5A to FIG. 5C In the embodiment of the present invention, the optical blocking pixel 140 is implemented by three transistors and one capacitor (3T1C) as an example. However, the present disclosure is not limited to this. In some embodiments, the optical blocking pixel 140 may also be implemented by a method similar to Figure 4B The invention can be realized by combining a four transistor and a capacitor (4T1C) with an optical barrier element, or by using any equivalent optical sensing circuit architecture with an optical barrier element.

[0101] Please also read Figure 6 , which is a schematic diagram illustrating the relationship between one of the plurality of optical sensing pixels 120, one of the plurality of optical blocking pixels 140, and the readout circuit 160 according to some embodiments of the present disclosure. Figure 6 As shown, the optical sensing pixel 120 can generate a sensing signal SIN to a first input terminal IN1 of a differential amplifier 162, and the optical blocking pixel 140 can generate a tracking signal TR to a second input terminal IN2 of the differential amplifier 162. The differential amplifier 162 receives the sensing signal SIN and the tracking signal TR to amplify the difference DIF between the sensing signal SIN and the tracking signal TR.

[0102] As mentioned above, the sensing signal SIN is used to reflect the light ILL (see Figure 2 ) and environmental factors related to environmental conditions, and the tracking signal TR is used to reflect the environmental factors. The output of the differential amplifier 162 can be expressed as:

[0103] The output of the differential amplifier 162

[0104] =GAIN*(sensing signal SIN – tracking signal TR)

[0105] =GAIN*[(optical sensing factor + environmental factor) – (environmental factor)]

[0106] =GAIN*(optical sensing factor)

[0107] GAIN is the gain parameter of the differential amplifier 162. In other words, the tracking signal TR can be used to compensate or reduce the environmental factors present in the sensing signal SIN. In this way, the correlation between the output of the differential amplifier 162 and the environmental factors is eliminated. The analog-to-digital converter 164 is used to convert the output of the differential amplifier 162 into an output signal OUT in a digital format.

[0108] like Figure 1 as well as Figure 6As shown, an optical sensing pixel 120 can generate a sensing signal SIN, and a sensing signal SIN will generate an output signal OUT after being processed by a differential amplifier 162 (based on a tracking signal TR generated by an optical blocking pixel 140 near the optical sensing pixel 120). The multiple output signals OUT generated by the multiple optical sensing pixels 120 can be collected to identify a fingerprint. For example, the multiple output signals OUT can be processed by a processor (such as a central processing unit, a graphics processing unit, a special application integrated circuit, not shown in the figure) equipped with a fingerprint recognition algorithm to identify the fingerprint. It should be particularly noted that the output signal OUT generated by the optical fingerprint sensing device 100 of the present disclosure will not be affected by environmental factors (such as temperature changes). In this way, the optical fingerprint sensing device 100 can perform fingerprint recognition with higher accuracy and can be used under various environmental conditions.

[0109] Please also read Fig. 7A , which is a schematic diagram of a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140 according to some embodiments of the present disclosure. Fig. 7A As shown, the optical fingerprint sensing device 100a includes a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140, which are distributed on a plane. The plane may be an upper surface of a touch display panel, a touch pad or a fingerprint sensor.

[0110] like Fig. 7A As shown, the plane includes a plurality of blocks, such as blocks Z1, Z2 and Z3, a plurality of optical blocking pixels 140 are respectively arranged at the center of each of the blocks Z1, Z2 and Z3, and a plurality of optical sensing pixels 120 are arranged around the plurality of optical blocking pixels 140. Fig. 7A As shown in FIG. 1 , in block Z1 , one optical blocking pixel 140 is disposed at the center of block Z1 , and eighty optical sensing pixels 120 are disposed around the optical blocking pixel 140 . Fig. 7A In the embodiment of FIG. 1 , each of the blocks Z1, Z2, and Z3 includes 9×9 pixels, but the present disclosure is not limited thereto. In some other embodiments, each block may include 3×3 pixels, 5×5 pixels, 7×7 pixels, or other combinations. In this example, the tracking signal TR generated by an optical blocking pixel 140 may be shared by all the optical sensing pixels 120 in the same block.

[0111] Please also read Figure 7B , which is a schematic diagram of a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140 according to some embodiments of the present disclosure. Figure 7BAs shown, the optical fingerprint sensing device 100b includes a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140, which are distributed on a plane. The plane may be an upper surface of a touch display panel, a touch pad or a fingerprint sensor.

[0112] like Figure 7B As shown, a plurality of optical blocking pixels 140 are arranged at the boundary of the plane, and a plurality of optical sensing pixels 120 are arranged in the inner area of ​​the plane.

[0113] Please also read Figure 7C , which is a schematic diagram of a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140 according to some embodiments of the present disclosure. Figure 7C As shown, the optical fingerprint sensing device 100c includes a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140, which are distributed on a plane. The plane may be an upper surface of a touch display panel, a touch pad or a fingerprint sensor.

[0114] like Figure 7C As shown, a plurality of optical blocking pixels 140 are arranged at the boundary of the plane and distributed in a plurality of blocks (see Fig. 7A At the center of the blocks Z1, Z2 and Z3 in the plane, a plurality of optical sensing pixels 120 are arranged in the inner area of ​​the plane.

[0115] Please also read Fig.7D , which is a schematic diagram of a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140 according to some embodiments of the present disclosure. Fig.7D As shown, the optical fingerprint sensing device 100d includes a plurality of optical sensing pixels 120 and a plurality of optical blocking pixels 140, which are distributed on a plane. The plane may be an upper surface of a touch display panel, a touch pad or a fingerprint sensor.

[0116] like Fig.7D As shown, the optical blocking pixels 140 and the optical sensing pixels 120 in the optical fingerprint sensing device 100d are arranged in a staggered manner. Fig.7D As shown, each optical blocking pixel 140 is disposed between two optical sensing pixels 120 in the vertical direction. In addition, each optical blocking pixel 140 is disposed between two optical sensing pixels 120 in the horizontal direction. In this example, the number of the optical blocking pixels 140 is the same as the number of the optical sensing pixels 120. Two adjacent pixels (including one optical sensing pixel 120 and one optical blocking pixel 140) can be paired with each other to sense an output signal OUT, so that the influence of temperature changes can be effectively eliminated.

[0117] Please also read Figure 8, which illustrates a method flow chart of an optical fingerprint sensing method 200 according to some embodiments of the present disclosure. The optical fingerprint sensing method 200 can be performed by the above-mentioned embodiments. Figures 1 to 7D The optical fingerprint sensing device 100 and 100a-100d is implemented.

[0118] like Figure 1 and Figure 8 As shown, step S210 is executed to generate a sensing signal SIN by a plurality of optical sensing pixels 120. Each of the plurality of optical sensing pixels 120 includes a first photodetector for sensing light passing through the optical path. Step S220 is executed to generate a tracking signal TR by a plurality of optical blocking pixels 140. Each of the plurality of optical blocking pixels 140 includes a second photodetector, and light is blocked from entering the second photodetector. Step S230 is executed to generate a plurality of output signals OUT by a differential amplifier 162 according to the difference DIF between the plurality of sensing signals SIN and the plurality of tracking signals TR.

[0119] For more details about the optical sensing pixel 120, the optical blocking pixel 140 and the differential amplifier 162, please refer to the previous Figures 1 to 6 The relevant embodiments are not described in detail here.

[0120] It should be particularly noted that the output signal OUT generated by the optical fingerprint sensing method 200 of the present disclosure will not be affected by environmental factors (such as temperature changes) because the tracking signal TR can be used to compensate for the environmental factors contained in the sensing signal SIN. In this way, the optical fingerprint sensing method 200 can perform fingerprint recognition with higher accuracy and can be used under various environmental conditions.

[0121] Although specific embodiments of the present disclosure have been disclosed with respect to the above embodiments, these embodiments are not intended to limit the present disclosure. Various substitutions and improvements may be performed in the present disclosure by a person of ordinary skill in the relevant art without departing from the principles and spirit of the present disclosure. Therefore, the scope of protection of the present disclosure is determined by the appended claims.

Claims

1. An optical fingerprint sensing device, characterized in that: Include: A plurality of optical sensing pixels, each of the plurality of optical sensing pixels comprises a first photodetector for sensing a light passing through a light path, and the plurality of optical sensing pixels are used to generate a plurality of sensing signals; A plurality of optical blocking pixels, each of the plurality of optical blocking pixels comprises a second photodetector, the light is blocked from entering the second photodetector, the plurality of optical blocking pixels are used to generate a plurality of tracking signals, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, the plane comprises a plurality of blocks, the plurality of optical blocking pixels are arranged at the center of the plurality of blocks, and the plurality of optical sensing pixels are arranged around the plurality of optical blocking pixels; as well as A readout circuit is used to generate a plurality of output signals according to the differences between the plurality of sensing signals and the plurality of tracking signals.

2. The optical fingerprint sensing device according to claim 1, characterized in that: Each of the plurality of optical sensing pixels further comprises an optical blocking component, and the light is irradiated to the first photodetector through at least one opening on the optical blocking component.

3. The optical fingerprint sensing device according to claim 2, characterized in that: The optical barrier assembly comprises: a color filter layer disposed above the first photodetector, wherein a first opening along the light path is disposed on the color filter layer; and A light shielding layer is disposed above the first photodetector, wherein a second opening along the light path is disposed on the light shielding layer, and the light irradiates the first photodetector through the first opening and the second opening.

4. The optical fingerprint sensing device according to claim 1, characterized in that: Each of the plurality of optical blocking pixels further includes an optical blocking component, and the light is blocked by the optical blocking component and does not enter the second photodetector.

5. The optical fingerprint sensing device according to claim 4, characterized in that: Each of the plurality of optical blocking pixels further comprises: a first transistor, wherein a gate of the first transistor is coupled to the second photodetector; a second transistor coupled between the gate of the first transistor and a system voltage potential; a third transistor coupled between the first transistor and a column output line; as well as A capacitor is coupled to the gate of the first transistor.

6. The optical fingerprint sensing device according to claim 5, characterized in that: The optical blocking component is configured to cover an area above the second photodetector.

7. The optical fingerprint sensing device according to claim 5, characterized in that: The optical blocking component is configured to cover the second photodetector and a region above the first transistor.

8. The optical fingerprint sensing device according to claim 5, characterized in that: The optical blocking component is configured to cover the second photodetector, the first transistor, the second transistor, the third transistor and an area above the capacitor.

9. The optical fingerprint sensing device according to claim 1, characterized in that: The readout circuit includes a differential amplifier. The differential amplifier includes a first input terminal and a second input terminal. The first input terminal is used to receive one of the plurality of sensing signals, and the second input terminal is used to receive one of the plurality of tracking signals.

10. An optical fingerprint sensing device, characterized in that: Include: A plurality of optical sensing pixels, each of the plurality of optical sensing pixels comprises a first photodetector for sensing a light passing through a light path, and the plurality of optical sensing pixels are used to generate a plurality of sensing signals; A plurality of optical blocking pixels, each of the plurality of optical blocking pixels comprises a second photodetector, the light is blocked from entering the second photodetector, the plurality of optical blocking pixels are used to generate a plurality of tracking signals, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, and the plurality of optical blocking pixels and the plurality of optical sensing pixels are arranged alternately with each other; as well as A readout circuit is used to generate a plurality of output signals according to the differences between the plurality of sensing signals and the plurality of tracking signals.

11. An optical fingerprint sensing method, characterized in that: Include: Generating a plurality of sensing signals by a plurality of optical sensing pixels, each of the plurality of optical sensing pixels comprising a first photodetector for sensing a light passing through a light path; A plurality of tracking signals are generated by a plurality of optical blocking pixels, each of the plurality of optical blocking pixels comprises a second photodetector, the light is blocked from entering the second photodetector, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, the plane comprises a plurality of blocks, the plurality of optical blocking pixels are arranged at the center of the plurality of blocks, and the plurality of optical sensing pixels are arranged around the plurality of optical blocking pixels; as well as A differential amplifier generates a plurality of output signals according to the differences between the plurality of sensing signals and the plurality of tracking signals.

12. The optical fingerprint sensing method according to claim 11, characterized in that: The light sensed by the plurality of sensing signals is used for detecting a fingerprint.

13. The optical fingerprint sensing method according to claim 12, characterized in that: The plurality of output signals are compensated based on the plurality of tracking signals.

14. An optical fingerprint sensing method, characterized in that: Include: Generating a plurality of sensing signals by a plurality of optical sensing pixels, each of the plurality of optical sensing pixels comprising a first photodetector for sensing a light passing through a light path; A plurality of tracking signals are generated by a plurality of optical blocking pixels, each of the plurality of optical blocking pixels comprises a second photodetector, the light is blocked from entering the second photodetector, the plurality of optical sensing pixels and the plurality of optical blocking pixels are distributed on a plane, and the plurality of optical blocking pixels and the plurality of optical sensing pixels are arranged alternately with each other; as well as A differential amplifier generates a plurality of output signals according to the differences between the plurality of sensing signals and the plurality of tracking signals.

Images