Fingerprint collection device and driving method thereof, display device

Abstract

A fingerprint acquisition device, its driving method, and a display device are provided, belonging to the field of fingerprint recognition technology. In this fingerprint acquisition device, the fingerprint acquisition circuit can provide a constant current to the photoelectric sensing circuit through the sensing acquisition line. Therefore, the fingerprint acquisition signal acquired by the fingerprint acquisition circuit through the sensing acquisition line can follow the voltage change of the first electrode of the photoelectric sensor. This eliminates the influence of large noise on the sensing acquisition line on the acquired fingerprint signal, ensuring that the fingerprint acquisition circuit can acquire a fingerprint signal with a sufficient signal-to-noise ratio. This, in turn, ensures a low false recognition rate and false rejection rate for fingerprint comparison and recognition, improving the reliability and accuracy of fingerprint recognition.

Description

Technical Field

[0001] This disclosure relates to the field of fingerprint recognition technology, and in particular to a fingerprint acquisition device, its driving method, and a display device. Background Technology

[0002] With the rapid development of technology, the demand for touchscreen display devices with fingerprint recognition capabilities is increasing rapidly. Currently, fingerprint authentication is often achieved by integrating a fingerprint acquisition module into the display device to collect fingerprint signals.

[0003] Currently, fingerprint acquisition modules generally include a fingerprint acquisition circuit and multiple photoelectric sensors for detecting fingerprints. The light emitted by the display screen in the display device can reach the photoelectric sensor after being reflected by the fingerprint, so that the photoelectric sensor can detect the light detection information (generally called photocurrent) reflected from different positions such as the ridges of the fingerprint. The fingerprint acquisition circuit can collect the light detection information sensed by the photoelectric sensor for fingerprint comparison and authentication.

[0004] However, due to some factors (such as the large noise generated by the numerous signal lines in the display screen), the fingerprint acquisition circuit has difficulty acquiring light detection information (i.e., ridge signals) with a sufficient signal-to-noise ratio, which in turn makes fingerprint comparison and authentication difficult, resulting in poor reliability and accuracy of fingerprint recognition. Summary of the Invention

[0005] This disclosure provides a fingerprint acquisition device, its driving method, and a display device, which can solve the problem of poor fingerprint detection accuracy in related technologies. The technical solution is as follows: On the one hand, a fingerprint acquisition device is provided, the fingerprint acquisition device comprising: multiple photoelectric sensors, multiple photoelectric sensing circuits corresponding one-to-one with the multiple photoelectric sensors, and a fingerprint acquisition circuit; The photoelectric sensing circuit is connected to the reset control line, the reset power line, the sensing scan line, the sensing acquisition line, and the first pole of the corresponding photoelectric sensor, respectively. It is used to control the connection and disconnection between the reset power line and the first pole of the photoelectric sensor in response to the reset control signal provided by the reset control line, and to transmit signals through the sensing acquisition line in response to the sensing scan signal provided by the sensing scan line. The second pole of the photoelectric sensor is connected to the drive power line. The fingerprint acquisition circuit is connected to multiple sensing and acquisition lines that are connected to the multiple photoelectric sensing circuits, and is used to input a constant current to the multiple photoelectric sensing circuits through the multiple sensing and acquisition lines, and to acquire the fingerprint acquisition signals output by the multiple photoelectric sensing circuits through the multiple sensing and acquisition lines.

[0006] Optionally, the fingerprint acquisition circuit includes: a current supply unit and a signal acquisition unit; The current supply unit is connected to the plurality of sensing and acquisition lines and is used to input a constant current to the plurality of photoelectric sensing circuits through the plurality of sensing and acquisition lines; The signal acquisition unit is connected to the multiple sensing acquisition lines and is used to acquire the fingerprint acquisition signals output by the multiple photoelectric sensing circuits through the multiple sensing acquisition lines.

[0007] Optionally, the signal acquisition unit includes: a plurality of voltage followers corresponding one-to-one with the plurality of sensing acquisition lines; The positive input terminal of the voltage follower is connected to the sensing acquisition line, and the negative input terminal of the voltage follower is connected to the output terminal of the voltage follower.

[0008] Optionally, the current supply unit includes: a constant current source; One end of the constant current source is connected to the constant current power supply terminal, and the other end of the constant current source is connected to the multiple sensing and acquisition lines. The constant current source is used to output the constant current based on the power signal provided by the constant current power supply terminal.

[0009] Optionally, the constant current source is a mirror constant current source, and the mirror constant current source includes: a main current source and a plurality of auxiliary current sources corresponding one-to-one with the plurality of sensing and acquisition lines; The main current source and the plurality of auxiliary current sources are all connected to the constant current power supply terminal, and the plurality of auxiliary current sources are also respectively connected to the main current source and the plurality of sensing and acquisition lines.

[0010] Optionally, the design parameters of the main current source and each of the auxiliary current sources are the same, so that the characteristic parameters of the main current source and each of the auxiliary current sources are the same, so as to generate multiple constant currents of the same magnitude.

[0011] Optionally, the main current source includes a first transistor; each of the auxiliary current sources includes a second transistor. The gate of the first transistor is connected to the second terminal of the first transistor, the gate of the second transistor is connected to the gate of the first transistor, the first terminal of the first transistor and the first terminal of the second transistor are both connected to the constant current power supply terminal, and the second terminal of the second transistor is connected to the sensing acquisition line.

[0012] Optionally, the second transistors included in each of the auxiliary current sources are centrally disposed on one side of the plurality of sensing and acquisition lines and connected to the plurality of sensing and acquisition lines through sensing leads; Alternatively, each of the auxiliary current sources includes a second transistor that is independently disposed on one side of the connected sensing acquisition line.

[0013] Optionally, the fingerprint acquisition device further includes: a plurality of switching units corresponding one-to-one with the plurality of auxiliary current sources; Each of the switch units is connected between a corresponding auxiliary current source and a sensing acquisition line corresponding to the auxiliary current source, and is also connected to a switch control line, and is used to control the on / off state of the auxiliary current source and the sensing acquisition line in response to the switch control signal provided by the switch control line.

[0014] Optionally, each of the switching units includes: a third transistor; The gate of the third transistor is connected to the switch control line, the first electrode of the third transistor is connected to the auxiliary current source, and the second electrode of the third transistor is connected to the sensing acquisition line.

[0015] Optionally, the fingerprint acquisition device is applied in a display device, the display device comprising: a panel area and a circuit area adjacent to each other, the panel area comprising: a display area and a peripheral area adjacent to each other; The plurality of photoelectric sensors and the plurality of photoelectric sensing circuits are all located in the display area; The signal acquisition unit in the fingerprint acquisition circuit is located in the circuit area; The current supply unit in the fingerprint acquisition circuit is located in the circuit area and integrated with the signal acquisition unit; or, the current supply unit in the fingerprint acquisition circuit is located in the peripheral area.

[0016] Optionally, the plurality of photoelectric sensors and the plurality of photoelectric sensing circuits are arranged in an array; each photoelectric sensing circuit located in the same column is connected to the same sensing and acquisition line; the photoelectric sensing circuit includes: a reset sub-circuit, a drive sub-circuit, and a switch sub-circuit; The reset sub-circuit is connected to the reset control line, the reset power supply line, and the drive node respectively, and is used to control the on / off state of the reset power supply line and the drive node in response to the reset control signal. The drive node is connected to the first pole of the photoelectric sensor. The driving sub-circuit is connected to the driving node, the reset power line and the output node respectively, and is used to control the potential of the output node in response to the potential of the driving node and the reset power signal provided by the reset power line; The switching sub-circuit is connected to the sensing scan line, the output node, and the sensing acquisition line respectively, and is used to control the on / off state of the output node and the sensing acquisition line in response to the sensing scan signal.

[0017] Optionally, the reset sub-circuit includes a reset transistor; the drive sub-circuit includes a drive transistor; the switch sub-circuit includes a switch transistor; and the photoelectric sensor includes an organic photodiode. The gate of the reset transistor is connected to the reset control line, the first terminal of the reset transistor is connected to the reset power supply line, and the second terminal of the reset transistor is connected to the drive node. The gate of the driving transistor is connected to the driving node, the first terminal of the driving transistor is connected to the reset power supply line, and the second terminal of the driving transistor is connected to the output node. The gate of the switching transistor is connected to the sensing scan line, the first electrode of the switching transistor is connected to the output node, and the second electrode of the switching transistor is connected to the sensing acquisition line. The anode of the organic photodiode is connected to the driving node as the first electrode of the photoelectric sensor, and the cathode of the organic photodiode is connected to the driving power line as the second electrode of the photoelectric sensor.

[0018] On the other hand, a driving method for a fingerprint acquisition device is provided, applied in the fingerprint acquisition device as described in the above aspect, the method comprising: In the first stage, the photoelectric sensing circuit responds to the reset control signal provided by the reset control line and controls the reset power line to conduct with the first pole of the photoelectric sensor. In the second stage, the fingerprint acquisition circuit provides a constant current to the photoelectric sensing circuit through the sensing acquisition line, and acquires the fingerprint acquisition signal first output by the photoelectric sensing circuit through the sensing acquisition line. In the third stage, the photoelectric sensing circuit responds to the reset control signal and controls the reset power line to disconnect from the first pole of the photoelectric sensor. In the fourth stage, the fingerprint acquisition circuit provides a constant current to the photoelectric sensing circuit through the sensing acquisition line, and acquires the fingerprint acquisition signal output by the photoelectric sensing circuit again through the sensing acquisition line.

[0019] In another aspect, a display device is provided, the display device comprising: a display panel, and a fingerprint acquisition device as described in the preceding aspect.

[0020] In summary, the beneficial effects of the technical solution provided in this disclosure can include at least the following: A fingerprint acquisition device, its driving method, and a display device are provided. In this fingerprint acquisition device, a photoelectric sensing circuit is connected to the first electrode of a photoelectric sensor. The fingerprint acquisition circuit can not only acquire the fingerprint signal output by the photoelectric sensing circuit through the sensing acquisition line for fingerprint detection and identification, but also provide a constant current to the photoelectric sensing circuit through the sensing acquisition line. This allows the voltage in the acquired fingerprint signal to change with the voltage of the first electrode of the photoelectric sensor, thereby eliminating the influence of large noise generated by the signal line or other factors on the acquired fingerprint signal, ensuring that the fingerprint acquisition circuit can reliably acquire accurate fingerprint signals, and thus ensuring good fingerprint detection accuracy. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a fingerprint acquisition device provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of another fingerprint acquisition device provided in this embodiment; Figure 3 This is a schematic diagram of the circuit structure of a fingerprint acquisition device provided in an embodiment of this disclosure; Figure 4 This is a schematic diagram of a constant current source provided in an embodiment of this disclosure; Figure 5 This is a schematic diagram of the circuit structure of a constant current source provided in an embodiment of this disclosure; Figure 6 This is a schematic diagram of a constant current source and a switching unit provided in an embodiment of the present disclosure; Figure 7 This is a schematic diagram of the circuit structure of a constant current source and a switching section provided in an embodiment of this disclosure; Figure 8 This is a schematic diagram of the structure of a fingerprint collection device and a display panel provided in an embodiment of this disclosure; Figure 9 This is a schematic diagram of another fingerprint acquisition device and display panel provided in this embodiment; Figure 10 This is a schematic flowchart of a driving method for a fingerprint acquisition device provided in an embodiment of this disclosure; Figure 11 This is a schematic diagram of the relevant signal timing of a fingerprint acquisition device provided in an embodiment of this disclosure; Figure 12 This is a schematic diagram of the structure of a display device provided in an embodiment of this disclosure. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0024] It is understood that the transistors used in all embodiments of this disclosure can be thin-film transistors, field-effect transistors, or other devices with similar characteristics. Based on their function in the circuit, the transistors used in the embodiments of this disclosure are mainly switching transistors. Since the source and drain of the switching transistors used here are symmetrical, their sources and drains are interchangeable. The source is referred to as the first terminal, and the drain as the second terminal, or vice versa. According to the configuration shown in the accompanying drawings, the middle terminal of the transistor is the gate, the signal input terminal is the source, and the signal output terminal is the drain. Furthermore, the switching transistors used in the embodiments of this disclosure can include any one or a combination of P-type and N-type transistors. Specifically, a P-type transistor conducts when the gate voltage is low and is cut off when the gate voltage is high, while an N-type transistor conducts when the gate voltage is high and is cut off when the gate voltage is low. Additionally, the multiple signals in each embodiment correspond to a first potential and a second potential. The first potential and the second potential only represent that the potential of the signal has two different states, and do not represent that the first potential or the second potential has a specific value.

[0025] Display devices are output devices that present image information in a visual form, such as multimedia display devices like televisions, mobile phones, tablets, navigation devices, and game consoles. In addition to general input devices such as buttons, keyboards, or mice, display devices can also include touchscreens for input, allowing users to easily and intuitively input information or commands. Furthermore, in recent years, fingerprints, as an example of biometric information, have been proposed for user authentication in areas such as online banking, product purchases, and security, leading to a surge in demand for touchscreen display devices with fingerprint recognition capabilities.

[0026] Currently, fingerprint recognition is often achieved by integrating a fingerprint sensing module within a display device as a fingerprint acquisition module. Furthermore, considering the high degree of system integration, the fingerprint sensing module is often integrated with the display pixels within the display area of ​​the display device. However, due to the small area after integration, the photocurrent generated by the fingerprint sensing module is relatively small, approximately tens of farn-amperes (fA). Moreover, because the display device contains thousands of scan lines and signal lines, there is significant noise, making it difficult to acquire accurate photocurrent, resulting in poor fingerprint authentication accuracy. Therefore, this disclosure provides a fingerprint acquisition device that amplifies the small photocurrent generated by the fingerprint sensing module to obtain a larger fingerprint acquisition signal while simultaneously achieving lower acquisition noise, resulting in a higher signal-to-noise ratio for the fingerprint acquisition signal.

[0027] like Figure 1 As shown, the fingerprint acquisition device includes: multiple photoelectric sensors 01, multiple photoelectric sensing circuits 02 corresponding to the multiple photoelectric sensors 01, and a fingerprint acquisition circuit 03.

[0028] The photoelectric sensing circuit 02 is connected to the reset control line RST, the reset power supply line Vrst, the sensing scan line Sense, the sensing acquisition line SL, and the first terminal of the corresponding photoelectric sensor 01. The second terminal of the photoelectric sensor 01 is connected to the drive power supply line ELVss. The photoelectric sensing circuit 02 controls the connection and disconnection between the reset power supply line Vrst and the first terminal of the photoelectric sensor 01 in response to the reset control signal provided by the reset control line RST, and transmits signals through the sensing acquisition line SL in response to the sensing scan signal provided by the sensing scan line Sense.

[0029] For example, the photoelectric sensing circuit 02 can control the reset power line Vrst to conduct with the first pole of the photoelectric sensor 01 when the reset control signal provided by the reset control line RST is at a first potential, so that the reset power signal provided by the reset power line Vrst is transmitted to the first pole of the photoelectric sensor 01 to reset the first pole of the photoelectric sensor 01; and it can also control the reset power line Vrst to disconnect from the first pole of the photoelectric sensor 01 when the reset control signal provided by the reset control line RST is at a second potential.

[0030] Furthermore, the photoelectric sensing circuit 02 can interact with the sensing acquisition line SL by inputting or outputting signals through the sensing acquisition line SL when the potential of the sensing scan signal provided by the sensing scan line Sense is the first potential; and it can not interact with the sensing acquisition line SL when the potential of the sensing scan signal provided by the sensing scan line Sense is the second potential.

[0031] Optionally, in this embodiment of the present disclosure, the first potential can be an effective potential, and the second potential can be an ineffective potential. Furthermore, for the N-type transistor in the photoelectric sensing circuit 02, the first potential can be a high potential relative to the second potential, i.e., the first potential can be a high potential, and the second potential can be a low potential; for the P-type transistor in the photoelectric sensing circuit 02, the first potential can be a low potential relative to the second potential, i.e., the first potential can be a low potential, and the second potential can be a high potential.

[0032] The fingerprint acquisition circuit 03 is connected to multiple sensing acquisition lines SL that are connected to multiple photoelectric sensing circuits 02. The fingerprint acquisition circuit 03 is used to provide a constant current to multiple photoelectric sensing circuits 02 through multiple sensing acquisition lines SL, and to acquire the fingerprint acquisition signals output by multiple photoelectric sensing circuits 02 through multiple sensing acquisition lines SL.

[0033] It is understood that the acquired fingerprint signal may include a voltage signal. By setting the fingerprint acquisition circuit 03 to provide a constant current to the photoelectric sensing circuit 02, the acquired voltage can follow the voltage change of the first electrode of the photoelectric sensor 01. Based on this, after acquiring the fingerprint signal twice, the adverse effects of some characteristic space differences and / or noise on the fingerprint acquisition signal can be eliminated, ensuring that the fingerprint acquisition circuit 03 can reliably and accurately acquire the fingerprint signal, thereby improving the accuracy of fingerprint recognition. Among them, characteristic space differences may be, for example, the difference between the threshold voltage of the driving transistor whose gate is connected to the first electrode of the photoelectric sensor 01 and the threshold voltage of the driving transistor of the first electrode of the adjacent pixel in the photoelectric sensing circuit 02; noise may be, for example, the noise when the reset power line Vrst transmits the reset power signal to the first electrode of the photoelectric sensor 01.

[0034] In summary, this disclosure provides a fingerprint acquisition device. In this device, a photoelectric sensing circuit is connected to the first electrode of a photoelectric sensor. The fingerprint acquisition circuit not only acquires the fingerprint acquisition signal output by the photoelectric sensing circuit via the sensing acquisition line for fingerprint comparison and authentication, but also provides a constant current to the photoelectric sensing circuit through the sensing acquisition line. This allows the fingerprint acquisition signal acquired by the fingerprint acquisition circuit via the sensing acquisition line to change with the voltage of the first electrode of the photoelectric sensor, thereby eliminating the influence of significant noise on the sensing acquisition line on the acquired fingerprint signal. This ensures that the fingerprint acquisition circuit can acquire a fingerprint signal with a sufficient signal-to-noise ratio, thus ensuring a low false recognition rate and false rejection rate for fingerprint comparison and recognition, and improving the reliability and accuracy of fingerprint recognition.

[0035] Optionally, refer to Figure 1As can be seen, multiple photoelectric sensors 01 and multiple photoelectric sensing circuits 02 can be arranged in an array. That is, similar to multiple rows and columns of display pixels in a display device, a fingerprint acquisition device may include multiple rows and columns of photoelectric sensors 01 and multiple rows and columns of photoelectric sensing circuits 02.

[0036] And continue to refer to Figure 1 It can be seen that the photoelectric sensing circuits 02 located in the same column can be connected to the same sensing acquisition line SL. Of course, photoelectric sensing circuits 02 located in different columns can be connected to different sensing acquisition lines SL. For distinction, refer to... Figure 1 The fingerprint acquisition device shown includes n columns of photoelectric sensing circuits 02, where n is an integer greater than 1. The sensing acquisition line SL connected to the first column of photoelectric sensing circuits 02 from left to right is labeled as SL1, and the sensing acquisition line SL connected to the nth column of photoelectric sensing circuits 02 is labeled as SLn. The labeling of the sensing acquisition lines SL connected to the other columns of photoelectric sensing circuits 02 is similar and will not be described in detail.

[0037] Optionally, in Figure 1 Based on this, taking a photoelectric sensing circuit 02 and a connected photoelectric sensor 01 as an example, Figure 2 A schematic diagram of another fingerprint acquisition device is shown. (Reference) Figure 2 It can be seen that each photoelectric sensing circuit 02 may include: a reset sub-circuit 021, a drive sub-circuit 022, and a switch sub-circuit 023.

[0038] The reset sub-circuit 021 can be connected to the reset control line RST, the reset power supply line Vrst, and the drive node P1, respectively. The reset sub-circuit 021 can be used to control the switching between the reset power supply line Vrst and the drive node P1 in response to the reset control signal. The drive node P1 is connected to the first electrode of the photoelectric sensor 01.

[0039] For example, the reset sub-circuit 021 can control the reset power line Vrst to conduct with the drive node P1 (i.e., the first pole of the photoelectric sensor 01) when the reset control signal is at the first potential; and can control the reset power line Vrst to disconnect from the drive node P1 when the reset control signal is at the second potential.

[0040] The driver sub-circuit 022 can be connected to the driver node P1, the reset power supply line Vrst, and the output node P2, respectively. The driver sub-circuit 022 can be used to control the potential of the output node P2 in response to the potential of the driver node P1 and the reset power supply signal provided by the reset power supply line Vrst.

[0041] It is understandable that the potential difference between the output node P2 and the driving node P1 (i.e., the potential of the first electrode of the photoelectric sensor 01) can control the current flowing through the driving sub-circuit 022. When the current flowing through the driving sub-circuit 022 is constant, the potential difference between the output node P2 and the first electrode of the photoelectric sensor 01 can remain constant accordingly. Therefore, the potential of the output node P2 can change with the change of the potential of the first electrode of the photoelectric sensor 01.

[0042] The switch sub-circuit 023 can be connected to the sensing scan line Sense, the output node P2, and the sensing acquisition line SL, respectively. The switch sub-circuit 023 can be used to control the on / off state of the output node P2 and the sensing acquisition line SL in response to the sensing scan signal.

[0043] For example, the switch sub-circuit 023 can control the output node P2 to be connected to the sensing acquisition line SL when the potential of the sensing scan signal is the first potential; and can control the output node P2 to be disconnected from the sensing acquisition line SL when the potential of the sensing scan signal is the second potential.

[0044] Optionally, continue to refer to Figure 2 It can be seen that the fingerprint acquisition circuit 03 may include a current supply unit 031 and a signal acquisition unit 032.

[0045] The current supply unit 031 can be connected to multiple sensing acquisition lines SL and is used to input a constant current to multiple photoelectric sensing circuits 02 through the multiple sensing acquisition lines SL.

[0046] The signal acquisition unit 032 can be connected to multiple sensing acquisition lines SL and is used to acquire fingerprint acquisition signals output by multiple photoelectric sensing circuits 02 through multiple sensing acquisition lines SL.

[0047] That is, a constant current can be provided by the current supply unit 031, and the voltage of the first electrode of the photoelectric sensor 01, which reacts to the fingerprint acquisition signal, can be acquired by the signal acquisition unit 032. It is understandable that... Figure 2 Only one sensing acquisition line SL is shown connected to a photoelectric sensing circuit 02.

[0048] Optionally, in Figure 2 On this basis, Figure 3 A schematic diagram of the circuit structure of a fingerprint acquisition device provided in an embodiment of this disclosure is shown. (Reference) Figure 3As can be seen, the reset sub-circuit 021 may include a reset transistor ST1. The drive sub-circuit 022 may include a drive transistor ST2. The switch sub-circuit 023 may include a switch transistor ST3. The photoelectric sensor 01 may include an organic photodiode OPD. Of course, in some other embodiments, the photoelectric sensor 01 may also include a photodiode PIN or other photoelectric sensor devices. This disclosure uses an organic photodiode OPD as an example for illustration.

[0049] Specifically, the gate of the reset transistor ST1 can be connected to the reset control line RST, the first terminal of the reset transistor ST1 can be connected to the reset power supply line Vrst, and the second terminal of the reset transistor ST1 can be connected to the drive node P1.

[0050] The gate of the driving transistor ST2 can be connected to the driving node P1, the first terminal of the driving transistor ST2 can be connected to the reset power supply line Vrst, and the second terminal of the driving transistor ST2 can be connected to the output node P2.

[0051] The gate of the switching transistor ST3 can be connected to the sensing scan line Sense, the first terminal of the switching transistor ST3 can be connected to the output node P2, and the second terminal of the switching transistor ST3 can be connected to the sensing acquisition line SL.

[0052] The anode of the organic photodiode (OPD) can be used as the first electrode of the photoelectric sensor 01 and connected to the driving node P1, while the cathode of the organic photodiode (OPD) can be used as the second electrode of the photoelectric sensor 01 and connected to the driving power line ELVss.

[0053] Optionally, Figure 3 The diagram also schematically illustrates the junction capacitance Cjopd of the organic photodiode (OPD) and the parasitic capacitance Cp of the gate of the driving transistor ST2, which is generated by wiring. The junction capacitance Cjopd and the parasitic capacitance Cp can be collectively referred to as storage capacitance, used to store the photocharge generated by the organic photodiode (OPD) during exposure.

[0054] Optionally, Figure 3The photoelectric sensing circuit 02 shown can be a 3T (i.e., including 3 transistors) structure. Furthermore, the reset transistor ST1 needs to be a transistor with low leakage current, requiring its leakage current to be less than the dark-state photocurrent of the organic photodiode. The driving transistor ST2 and the switching transistor ST3 can be P-type transistors or N-type transistors. The N-type transistor can be made of oxide material, and the P-type transistor can be made of low-temperature polysilicon (LTPS) material. Accordingly, the 3T structure of the low-temperature polysilicon oxide (LTPO) photoelectric sensing circuit 02 can include: an oxide N-type transistor ST1 and two LTPS P-type transistors ST2 and ST3, reusing the low leakage current of the oxide reset transistor ST1 and the good stability of the LTPS driving transistor ST2. In addition, the transistors provided in this embodiment can all be metal-oxide-semiconductor (MOS) field-effect transistors, also known as MOS transistors; N-type transistors are NMOS transistors, and P-type transistors are PMOS transistors.

[0055] Combination Figure 3 It can be seen that the N-type reset transistor ST1, under the control of the reset control signal provided by the reset control line RST, controls the reset power supply line Vrst to transmit the reset power signal to the gate of the driving transistor ST2 and the anode of the photodiode OPD, thereby achieving reset. The P-type switching transistor ST3, under the control of the sensing scan signal provided by the sensing scan line Sense, controls the source of the P-type driving transistor ST2 to conduct with the sensing acquisition line SL, thereby achieving stable constant current and source voltage output.

[0056] Based on this, firstly, after the photocurrent generated by the photodiode OPD is reset in the junction capacitance Cjopd and parasitic capacitance Cp, under light exposure, the photocurrent generated by the photodiode OPD can charge the junction capacitance Cjopd and parasitic capacitance Cp, increasing the charge in the capacitors and raising the voltage across the capacitors. This causes the gate voltage of the driving transistor ST2 to rise from the voltage of the reset power supply signal provided by the reset power supply line Vrst. Since the current of the driving transistor ST2 is a constant current provided by the current supply section 031 of the acquisition circuit 03 through the sensing acquisition line SL and the switching transistor ST3, the gate-source voltage of the driving transistor ST2 is constant. Therefore, the voltage of the fingerprint acquisition signal acquired by the acquisition circuit 03 is the source voltage of the driving transistor ST2 output through the switching transistor ST3 and the sensing acquisition line SL, i.e., the voltage of the output node P2. The voltage of the output node P2 can change with the voltage of the gate of the driving transistor ST2 (i.e., the voltage of the first terminal of the photodiode OPD).

[0057] Optionally, in some embodiments, the light-emitting element in the display device can be an organic light-emitting diode (OLED). The processes for the photodiode (OPD) and the OLED can be shared, thereby simplifying the manufacturing process.

[0058] For example, the cathode of an OPD (Optical Photodiode) and the cathode of an OLED (Optical Light-Emitting Device) can be located on the same layer and connected to the same driving power line ELvss. Accordingly, both can receive the driving power signal provided by the driving power line ELvss. For instance, the voltage of the driving power signal provided by the driving power line ELvss can be between -2 volts (V) and 3V. Furthermore, the anode of the OLED can also be connected to the pull-up power line ELVdd via the pixel circuit. The pull-up power signal provided by the pull-up power line ELVdd can be greater than the driving power signal provided by the driving power line ELvss.

[0059] Optionally, in some embodiments, the constant current power supply terminal Vp connected to the constant current source CCS can be shared with the pull-up power supply line ELVdd connected to the pixel circuit. This simplifies wiring and saves costs.

[0060] It is understandable that "being in the same layer" can refer to a layer structure formed by using the same film deposition process to create a specific pattern, and then using the same photomask to pattern this film layer in a single patterning process. Depending on the specific pattern, the single patterning process may include multiple exposure, development, or etching processes, and the specific pattern in the resulting layer structure can be continuous or discontinuous. That is, multiple elements, components, structures, and / or parts located in the "same layer" are made of the same material and formed through the same single patterning process. This simplifies the manufacturing process and saves manufacturing costs.

[0061] Optionally, continue to refer to Figure 3 As can be seen from the schematic diagram of the current supply unit 031 shown, the current supply unit 031 may include a constant current source (CCS).

[0062] One end of the constant current source CCS can be connected to the constant current power supply terminal Vp, and the other end of the constant current source CCS can be connected to multiple sensing and acquisition lines SL. The constant current source CCS can be used to output a constant current based on the power signal provided by the constant current power supply terminal Vp. It is understandable that... Figure 3 Only one sensing acquisition line SL is shown.

[0063] Optionally, continue to refer to Figure 3 As can be seen, the signal acquisition unit 032 may include multiple voltage followers (VF) that correspond one-to-one with multiple sensing acquisition lines SL.

[0064] The positive input terminal (+) of the voltage follower VF can be connected to the sensing acquisition line SL, and the negative input terminal (-) of the voltage follower VF can be connected to the output terminal Vo of the voltage follower VF.

[0065] It's understandable that a voltage follower (VF) can also be called a buffer amplifier or a voltage follower operational amplifier (OP) circuit. The output voltage of a voltage follower (VF) is the same as its input voltage, but its current gain can be increased. Therefore, the function of a voltage follower (VF) is to convert the input impedance to a lower output impedance, thereby providing current amplification and voltage following functions. Correspondingly, the signal acquisition unit 032 can also be called an analog front-end (AFE) circuit.

[0066] Optionally, in some embodiments, the signal acquisition unit 032 may include only one voltage follower VF. In addition, multiple sensing acquisition lines SL can be connected in a one-to-many manner through a multiplexed MUX switch, thereby simplifying the structure of the signal acquisition unit 032 and saving the cost of manufacturing the signal acquisition unit 032.

[0067] That is, in this embodiment of the present disclosure, the fingerprint acquisition circuit 03 may include a bias constant current source CCS and a voltage follower VF. The constant current source CCS can provide a constant current to the driving transistor ST2 via the switching transistor ST3, such that the gate-source voltage difference Vgs of the driving transistor ST2... ST2 With a fixed voltage, the source voltage of the driving transistor ST2 changes with the gate voltage, which means that the source voltage output by the driving transistor ST2 can follow the gate voltage.

[0068] Optionally, the gate-source voltage difference Vgs of the driving transistor ST2 ST2 It can be: Vgs ST2= ; Among them, Vth ST2 It can refer to the threshold voltage driving transistor ST2, Is0 can refer to the constant current provided by the constant current source CCS, and K ST2 This refers to the process parameters of the driving transistor ST2.

[0069] For any transistor, its process parameter K can satisfy: K ​​= µ can refer to the transistor's mobility, Cox can refer to the transistor's gate capacitance, and W and L can refer to the transistor's channel width and length, respectively. The following examples are similar and will not be repeated.

[0070] Based on the above description, the fingerprint acquisition device provided in this embodiment can be an in-screen fingerprint amplification acquisition device with follow-output, including a 3T circuit of an organic photoelectric sensor (APS) and a voltage follower operational amplifier circuit with constant current bias.

[0071] Understandably, in combination Figure 1 Because the photoelectric sensing circuit 02 needs to be led out to the fingerprint acquisition circuit 03 via a relatively long sensing acquisition line SL, and because the sensing acquisition line SL crosses other signal lines in the display screen (such as the scan line Gate connected to the display pixel circuit), it will form parasitic capacitance, creating loads Cload and Rload on the sensing acquisition line SL, thus generating noise. For example, in a certain display screen, the noise amplitude of the scan signal provided by the scan line Gate was tested to be approximately 18 millivolts (mV). The scan signal provided by the scan line Gate refers to the signal generated by the gate driver circuit GOA after the pull-up power supply signal VGH and pull-down power supply signal VGL are generated by the charge pump of the display driver integrated chip (DDIV).

[0072] Optionally, in some embodiments, the fingerprint acquisition circuit 03 often employs a current follower including an operational amplifier (OP), a sampling resistor (Rs), and a filter capacitor (Cf). Due to structural limitations, for scanning signal noise frequencies between 100 kHz and 10 MHz, the noise amplification factor of the current follower is generally greater than 1, and can reach a maximum of 4.5 times. That is, noise at this frequency will be amplified, and after passing through the sensing acquisition line SL and the current follower (i.e., the operational amplifier (OP), sampling resistor (Rs), and filter capacitor (Cf), the output noise of the fingerprint acquisition circuit 03 will reach 49 mV, far exceeding the 18 mV noise on the scan line gate. However, in this embodiment, since a voltage follower (VF) is used to form the fingerprint acquisition circuit 03, and the noise amplification factor of the voltage follower (VF) is generally 1, the noise during fingerprint acquisition can be effectively reduced. For example, by using a voltage follower VF, the output noise of the fingerprint acquisition circuit 03 can be reduced to approximately 4.8mV, which is significantly lower than the 49mV output noise of the fingerprint acquisition circuit 03 when using a current follower. This further ensures better accuracy of the acquired fingerprint signal, thereby improving the precision of fingerprint detection.

[0073] Optionally, Figure 4 This is a schematic diagram of the circuit structure of a constant current source provided in an embodiment of this disclosure. (Reference) Figure 4 It can be seen that the constant current source CCS can be a mirror constant current source, and the mirror constant current source CCS can include: the main current source S1, and multiple mirror auxiliary current sources S2 corresponding one-to-one with multiple sensing acquisition lines SL1, SL2, SL3...SLn.

[0074] The main current source S1 and multiple auxiliary current sources S2 can be connected to the constant current power supply terminal Vp, and the multiple auxiliary current sources S2 can also be connected to the main current source S1 and multiple sensing and acquisition lines SL1, SL2, SL3...SLn respectively. Thus, a constant current can be generated by the main current source S1, and the constant current generated by the main current source S1 can be mirrored and transmitted to the connected sensing and acquisition lines SL by the auxiliary current sources S2.

[0075] Optionally, Figure 5 This is a schematic diagram of the circuit structure of a constant current source provided in an embodiment of this disclosure. For example... Figure 5 As shown, the main current source S1 may include: a first transistor T1. Each auxiliary current source S2 may include: a second transistor T2. For distinction, Figure 5 The multiple second transistors T2 that connect to multiple sensing and acquisition lines SL1, SL2, SL3...SLn are respectively labeled as T21, T22, T23...T2n.

[0076] In this configuration, the gate of the first transistor T1 can be connected to its second terminal, and the gate of the second transistor T2 can be connected to the gate of the first transistor T1. The first terminals of both the first transistor T1 and the second transistor T2 can be connected to the constant current power supply terminal Vp, and the second terminal of the second transistor T2 can be connected to the sensing acquisition line SL. Optionally, as described above, the first terminal can be the source, and the second terminal can be the drain.

[0077] It is understandable that, taking an example consisting of n columns of photodiodes (OPDs), i.e., n sensing acquisition lines SL1, SL2, SL3...SLn, the fingerprint acquisition signals generated after exposure of the n photodiodes (OPDs) located in the same row are generally acquired simultaneously. Correspondingly, the constant current source (CCS) needs to simultaneously provide the same constant current to the n channels (i.e., the n sensing acquisition lines SL1, SL2, SL3...SLn). Therefore, in this embodiment, the design parameters of the main current source S1 and each auxiliary current source S2 can be the same, so that the characteristic parameters of the main current source S1 and each auxiliary current source S2 are identical, thereby generating multiple constant currents of the same magnitude.

[0078] For the main current source S1 and each auxiliary current source S2, the design parameters can refer to the threshold voltage Vth of the transistors included, and / or the gate capacitance Cox and the channel width-to-length ratio W / L, etc. The same design parameters can make the driving characteristics of each transistor the same, thereby outputting a constant current of the same magnitude.

[0079] Understandably, in combination Figure 4 and Figure 5 The gate and drain of the first transistor T1 are connected, and the constant current Is0 output by the first transistor T1 can satisfy: Is0 Formula (1); Among them, K T1 This could refer to the process parameters of the first transistor T1, Vgs. T1 It can refer to the gate-source voltage difference, Vth, of the first transistor T1. T1 This can refer to the threshold voltage of the first transistor T1. Based on the above formula (1), the gate-source voltage difference Vgs of the first transistor T1 can be determined. T1 For a constant voltage, it is expressed by the following formula: Formula (2); Assuming the voltage of the constant current signal provided by the constant current power supply terminal Vp is Vp0, the gate voltage Vg of the first transistor T1 can be determined based on formula (2). T1 It can satisfy: Formula (3); It is understandable that, for the first transistor T1 included in the main current source S1 and the second transistor T2 included in each auxiliary current source S2, the process parameter K is the same (e.g., both are 0). The threshold voltage Vth is the same for all of them (e.g., both are 0). ), that is: ; ; in, This could refer to the process parameters of the second transistor T21. This could refer to the process parameters of the second transistor T22. This could refer to the process parameters of the second transistor T23. This could refer to the process parameters of the second transistor T2n. This could refer to the threshold voltage of the second transistor T21. This could refer to the threshold voltage of the second transistor T22. This could refer to the threshold voltage of the second transistor T23. This could refer to the threshold voltage of the second transistor T2n.

[0080] Therefore, it can be determined that the gate voltages of the first transistor T1 included in the main current source S1 and the second transistor T2 included in each auxiliary current source S2 can all be the same (e.g., both are...). Correspondingly, the gate-source voltage difference can be the same (e.g., both are Vgs). T And the output constant current can all be the same (e.g., all are...). ). That is,

[0081]

[0082] Optionally, Figure 6 This is a schematic diagram of the structure of another fingerprint acquisition device provided in this disclosure embodiment. For example... Figure 6 As shown, the fingerprint acquisition device may also include multiple switching units SW corresponding to multiple auxiliary current sources S2.

[0083] Each switch SW can be connected between a corresponding auxiliary current source S2 and a sensing acquisition line SL corresponding to the auxiliary current source S2, and can also be connected to the switch control line Ctrl. It can be used to control the on / off state of an auxiliary current source S2 and a sensing acquisition line SL in response to the switch control signal provided by the switch control line Ctrl.

[0084] For example, each switch unit SW can control an auxiliary current source S2 and a sensing acquisition line SL to be turned on when the potential of the switch control signal provided by the switch control line Ctrl is a first potential; and can control an auxiliary current source S2 and a sensing acquisition line SL to be disconnected when the potential of the switch control signal provided by the switch control line Ctrl is a second potential.

[0085] That is, a switch unit SW can also be set to control the on / off state of the auxiliary current source S2 and the sensing acquisition line SL under the control of the switch control signal. In this way, by flexibly setting the switch control signal, the auxiliary current source S2 can be connected or not connected to the sensing acquisition line SL, thereby selecting whether to provide or not to provide a constant current to the photoelectric sensing circuit 02 through the sensing acquisition line SL, thus providing better control flexibility.

[0086] Optionally, in some embodiments, multiple switch units SW can be connected to the same switch control line Ctrl. Alternatively, in other embodiments, multiple switch units SW can be connected one-to-one to multiple switch control lines Ctrl. This further improves control flexibility.

[0087] Optionally, Figure 7 This is a schematic diagram of a circuit structure including a switching unit provided in an embodiment of this disclosure. Figure 7 As shown, each switching section SW may include: a third transistor T3. For distinction, Figure 7 The multiple third transistors T3 connecting the multiple sensing and acquisition lines SL1, SL2, SL3...SL1...SLn-2, ​​SLn-1 and SLn are respectively labeled as T31, T32, T33...T3i...T3n-2, T3n-1 and T3n. The second transistor T2 is labeled in the same way, and will not be described again.

[0088] The gate of the third transistor T3 can be connected to the switch control line Ctrl, the first terminal of the third transistor T3 can be connected to the auxiliary current source S2, and the second terminal of the third transistor T3 can be connected to the sensing acquisition line SL.

[0089] Optionally, the fingerprint acquisition device provided in this disclosure can be applied to a display device. For example... Figure 8 and Figure 9 As shown, the display device may include: a panel area A1 and a circuit area B1 that are adjacent to each other, and referenced Figure 9 As can be seen, panel area A1 can include: the adjacent display area AA and the surrounding area BB. Panel area A1 can also be referred to as the area where the display screen is located.

[0090] For example, the circuit area B1 shown in the figure can be located below the panel area A1, and the display area AA and the peripheral area BB can be arranged sequentially along the direction closest to the circuit area B1. Of course, the figure is only for illustrative purposes. In some other embodiments, the circuit area B1 can also be located at other positions in the panel area A1. The display area AA and the peripheral area BB can be arranged in other directions. Alternatively, the peripheral area BB can surround the display area AA.

[0091] Optionally, such as Figure 8 and Figure 9 As shown, multiple photoelectric sensors 01 (e.g., photodiodes OPD) and multiple photoelectric sensing circuits 02 can all be located in the display area AA. The display pixels in the display device can also be located in this display area AA, thereby enabling the display area AA to display an image. That is, the display area AA can be the area where the photodiodes OPD and the display pixels are located.

[0092] Optionally, such as Figure 8 and Figure 9 As shown, the signal acquisition unit 032 (i.e., the AFE circuit) in the fingerprint acquisition circuit 03 can be located in circuit area B1. Furthermore, the AFE circuit can be integrated inside the read-out integrated circuit chip (ROIC). The ROIC can be used to provide a switch control signal to the switch control line Ctrl connected to the switch section SW, thereby controlling the output timing of the constant current source CCS.

[0093] Alternatively, in one embodiment, such as Figure 8 As shown, the current supply unit 031 (i.e., constant current source CCS) in the fingerprint acquisition circuit 03 can be located in circuit area B1 and integrated with the signal acquisition unit 032. That is, the constant current source CCS can be integrated with the AFE circuit inside the ROIC.

[0094] Alternatively, in another embodiment, such as Figure 9 As shown, the current supply unit 031 (i.e., constant current source CCS) in the fingerprint acquisition circuit 03 can be located in the peripheral area BB. That is, the constant current source CCS can be set in the peripheral area BB of the display area AA on the display screen, rather than being integrated into the ROIC together with the AFE circuit.

[0095] Optionally, in some embodiments, the peripheral area BB may also be provided with gate drive circuit GOA, power lines, control signal lines, drive data lines and other signal traces.

[0096] Optionally, combined Figure 8It can also be seen that, in one embodiment, the second transistor T2 included in each auxiliary current source S2 can be independently disposed on one side of the connected sensing acquisition line SL. In this way, it can be directly connected to the corresponding sensing acquisition line SL.

[0097] Or, combine Figure 9 It can also be seen that, in another embodiment, the second transistor T2 included in each auxiliary current source S2 can be centrally located on one side of multiple sensing acquisition lines SL and connected to multiple sensing acquisition lines SL through sensing leads SSL.

[0098] It is understood that the above-mentioned independent or integrated settings are not limited to Figure 8 The constant current source CCS shown is integrated inside the ROIC or Figure 9 The scheme shown has a constant current source CCS located in the peripheral region BB.

[0099] That is, in one embodiment of this disclosure, the constant current source CCS can be placed inside the ROIC. Due to process limitations, the size of the transistors (e.g., MOSFETs) inside the ROIC can be made smaller. Therefore, the second transistor T2 included in each auxiliary current source S2 can be placed near the corresponding connected sensing and acquisition line SL to ensure the accuracy of the provided constant current. Of course, in this embodiment, the second transistor T2 included in each auxiliary current source S2 can also be fabricated together and connected to the sensing and acquisition line SL through the sensing lead SSL. In this way, the accuracy of the provided constant current can also be improved, and the characteristic differences of the transistors caused by space differences can also be reduced.

[0100] In another embodiment of this disclosure, the constant current source CCS can be placed in the peripheral area BB of the display screen. Considering the differences in transistor characteristics due to the large-size manufacturing process of transistors within the display screen, the second transistor T2 included in each auxiliary current source S2 can be fabricated together, that is, centrally located on one side of multiple sensing acquisition lines SL, and connected to the multiple sensing acquisition lines SL via sensing leads SSL. In this way, the design parameters of each second transistor T2 can be made more similar, thereby making the driving characteristics of each second transistor T2 the same, ensuring that the same constant current is provided to multiple photoelectric sensing circuits 02 through multiple sensing acquisition lines SL. Of course, in this embodiment, the second transistor T2 included in each auxiliary current source S2 can also be placed near the corresponding connected sensing acquisition line SL.

[0101] Optionally, combined Figure 8 and Figure 9Furthermore, it can be seen that the fingerprint acquisition device may include an array of m rows and n columns of photodiodes (OPDs) and corresponding multiple photoelectric sensing circuits (O2). Based on this, fingerprint information for each row can be acquired sequentially by scanning row by row, acquiring n columns of fingerprint information each time, which are then transmitted one-to-one to the corresponding fingerprint acquisition circuits (O3) via n sensing lines. Here, m can be an integer greater than 1. Figure 8 and Figure 9 The circuit structure of a photoelectric sensing circuit 02 is also schematically shown.

[0102] In summary, this disclosure provides a fingerprint acquisition device. In this device, a photoelectric sensing circuit is connected to the first electrode of a photoelectric sensor. The fingerprint acquisition circuit not only acquires the fingerprint acquisition signal output by the photoelectric sensing circuit via the sensing acquisition line for fingerprint comparison and authentication, but also provides a constant current to the photoelectric sensing circuit through the sensing acquisition line. This allows the fingerprint acquisition signal acquired by the fingerprint acquisition circuit via the sensing acquisition line to change with the voltage of the first electrode of the photoelectric sensor, thereby eliminating the influence of significant noise on the sensing acquisition line on the acquired fingerprint signal. This ensures that the fingerprint acquisition circuit can acquire a fingerprint signal with a sufficient signal-to-noise ratio, thus ensuring a low false recognition rate and false rejection rate for fingerprint comparison and recognition, and improving the reliability and accuracy of fingerprint recognition.

[0103] This disclosure also provides a driving method for a fingerprint acquisition device, which can be applied to fingerprint acquisition devices as described above. Figure 10 As shown, the method includes: Step 1001: In the first stage, the photoelectric sensing circuit responds to the reset control signal provided by the reset control line and controls the reset power line to conduct with the first pole of the photoelectric sensor.

[0104] Step 1002: In the second stage, the fingerprint acquisition circuit provides a constant current to the photoelectric sensor circuit through the sensing acquisition line, and acquires the fingerprint acquisition signal output by the photoelectric sensor circuit for the first time through the sensing acquisition line.

[0105] Step 1003: In the third stage, the photoelectric sensing circuit responds to the reset control signal and controls the reset power line to disconnect from the first pole of the photoelectric sensor.

[0106] Step 1004: In the fourth stage, the fingerprint acquisition circuit provides a constant current to the photoelectric sensor circuit through the sensing acquisition line, and acquires the fingerprint acquisition signal output by the photoelectric sensor circuit again through the sensing acquisition line.

[0107] That is, the fingerprint acquisition device provided in this embodiment can complete the acquisition of photocurrent generated by the photoelectric sensor in four stages within one cycle. Optionally, with Figure 3 Taking the structure shown as an example, combined with Figure 11 The following diagram illustrates the signal timing and explains the working principle of the fingerprint acquisition device: In the first stage t01 of this cycle, the potential of the reset control signal provided by the reset control line RST and the potential of the sensing scan signal provided by the sensing scan line Sense can both be high. Correspondingly, in the photoelectric sensing circuit 02, the reset transistor ST1 can be turned on, and the switching transistor ST3 can be turned off. This allows the reset power supply line Vrst to be connected to the driving node P1 (i.e., the anode of the photodiode OPD and the gate of the driving transistor ST2). At this time, the reset power supply signal provided by the reset power supply line Vrst can be transmitted to the driving node P1, that is, it can be written to the anode of the photodiode OPD and its junction capacitance Cjopd, and to the gate of the driving transistor ST2 and its parasitic capacitance Cp, realizing the reset function and eliminating the residual information stored in the junction capacitance Cjopd and parasitic capacitance Cp before the fingerprint acquisition signal is collected. Accordingly, this first stage t01 can also be called the reset stage.

[0108] Optionally, assuming the driving power supply signal provided by the driving power supply line ELVss connected to the cathode of the photodiode OPD is -2.4V, then to ensure that the photodiode OPD is in a reverse bias state, the voltage of the reset power supply signal transmitted to the cathode of the photodiode OPD should be less than -2.4V, that is, the voltage Vrst1 of the reset power supply signal provided by the reset power supply line Vrst < -2.4V. Furthermore, assuming that the rise of the anode voltage of the photodiode OPD and the gate voltage of the driving transistor ST2 is between 0 and 3V through photocurrent integration, then the voltage Vrst1 of the reset power supply signal should be between -2.4V and -5.4V.

[0109] In the second stage t02 of this cycle, the potential of the reset control signal provided by the reset control line RST and the potential of the sensing scan signal provided by the sensing scan line Sense can both be low. Correspondingly, in the photoelectric sensing circuit 02, the reset transistor ST1 can be turned off, and the switching transistor ST3 can be turned on. This allows the sensing acquisition line SL to be connected to the second terminal of the driving transistor ST2. At this time, the constant current source CCS can provide a constant current Is0 to the driving transistor ST2 through the sensing acquisition line SL, and the driving transistor ST2 can satisfy: Formula (4); and then, Formula (5); and then, Formula (6); Among them, Vs ST2It can refer to the source voltage, Vg, of the driving transistor ST2. ST2 It can refer to the gate voltage, Vth, of the driving transistor ST2. ST2 It can refer to the threshold voltage of the driving transistor ST2, K. ST2 This could refer to the process parameters of the driving transistor ST2. Because in the second stage t02, the photodiode OPD has not yet been exposed to generate photocurrent, the gate voltage Vg of the driving transistor ST2 at this time... ST2 This refers to the voltage Vrst1 of the reset power signal written in the first stage t01. Therefore, in the second stage t02, the output voltage Vo1 of the voltage follower VF after it first acquires the fingerprint acquisition signal through the sensing acquisition line SL (i.e., the fingerprint acquisition signal first output by the photoelectric sensor circuit 02 through the sensing acquisition line SL) can satisfy the following: Formula (7); Based on the above formula (7), it can be seen that the voltage Vo1 collected in the first time includes the voltage Vrst1 of the reset power supply signal and the threshold voltage of the driving transistor ST2. and Among them, the threshold voltage constant current Is0 and These are all fixed parameter values ​​related to the driving transistor ST2. Accordingly, the second stage t02 can also be called the first sampling and detection stage.

[0110] In the third stage t03 of this cycle, the reset control signal provided by the reset control line RST can be at a low potential, while the sensing scan signal provided by the sensing scan line Sense can be at a high potential. Correspondingly, in the photoelectric sensing circuit 02, both the reset transistor ST1 and the switching transistor ST3 can be turned off. Under light exposure, the photodiode OPD can generate a photocurrent Iopd ranging from several hundred fA to several pA, thereby charging the junction capacitance Cjopd and the parasitic capacitance Cp. After an exposure time Tem, the storage capacitance (including the junction capacitance Cjopd and the parasitic capacitance Cp) increases by a charge Q. 存储电容 It can satisfy: Q 存储电容 =Iopd×Tem formula (8); And, the voltage change V across the storage capacitor 存储电容 It can satisfy: V 存储电容 = Formula (9); That is, the anode voltage of the photodiode OPD and the gate voltage of the driving transistor ST2 can both be increased from the reset power supply signal voltage Vrst1 in the previous stage to Vrst1+ after the exposure time Tem. Here, Cjopd1 can refer to the capacitance value of the junction capacitance Cjopd, and Cp1 can refer to the capacitance value of the parasitic capacitance Cp. Correspondingly, the third stage t03 can also be called the exposure stage.

[0111] In the fourth stage t04 of this cycle, the potential of the reset control signal provided by the reset control line RST and the potential of the sensing scan signal provided by the sensing scan line Sense can both be low. Correspondingly, in the photoelectric sensing circuit 02, the reset transistor ST1 can be turned off, and the switching transistor ST3 can be turned on. This allows the sensing acquisition line SL to be connected to the second terminal of the switching transistor ST3. At this time, the constant current source CCS can provide a constant current Is0 to the driving transistor ST2 through the sensing acquisition line SL, and the driving transistor ST2 can satisfy:

[0112]

[0113] Formula (10); Accordingly, in the fourth stage t04, the output voltage Vo2 of the voltage follower VF after acquiring the fingerprint acquisition signal for the second time through the sensing acquisition line SL (that is, the fingerprint acquisition signal output again by the photoelectric sensing circuit 02 through the sensing acquisition line SL) can satisfy: Formula (11); Based on the above formula (11), it can be seen that the voltage Vo2 collected in the second time includes the voltage Vrst1 of the reset power supply signal and the voltage change term generated by the photodiode OPD. Threshold voltage of driving transistor ST2 and invariant terms Correspondingly, the fourth stage t04 can also be called the second sampling and detection stage or the photocurrent detection stage of the photodiode OPD.

[0114] Based on the above formulas (7) and (11), it can be seen that the difference Vo between the voltage Vo2 of the second sample and the voltage Vo1 of the first sample can satisfy:

[0115]

[0116] Formula (12); Based on the above formula (12), it can be seen that after two samplings, the voltage Vrst1 of the reset power supply signal in the two samplings can be eliminated, as well as the threshold voltage of the driving transistor ST2. and invariant terms In this way, on the one hand, the threshold voltage caused by transistor manufacturing process can be eliminated. The offset affects the acquired fingerprint signal; on the other hand, it can also eliminate the influence of noise generated by the reset power line Vrst on the acquired fingerprint signal, ensuring better acquisition accuracy of the fingerprint signal, and thus ensuring better fingerprint recognition accuracy.

[0117] For example, when the reset power supply signal voltage Vrst1 provided by the reset power supply line Vrst is written into the anode of the photodiode OPD and the gate of the driving transistor ST2, noise δVRST is generated. Therefore, the output voltage Vo1 after the first fingerprint acquisition signal is acquired through the sensing acquisition line SL and the output voltage Vo2 after the second fingerprint acquisition signal is acquired through the sensing acquisition line SL will both contain this noise δVRST. That is: The output voltage Vo1 after the first fingerprint acquisition signal is acquired via the sensing acquisition line SL can meet the following requirements: Formula (13); The output voltage Vo2 after the fingerprint acquisition signal is acquired for the second time via the sensing acquisition line SL can meet the following requirements: Formula (14); Based on the above formulas (13) and (14), it can be seen that the difference Vo between the voltage Vo2 of the second sample and the voltage Vo1 of the first sample can still satisfy: Formula (15); That is, after two samplings, the noise δVRST written from the reset power line Vrst to the gate of the driving transistor ST2 during the two samplings can be eliminated in the same way.

[0118] Combining the above formula (15), assuming that the photocurrents generated by the valleys and ridges of the fingerprint on the photodiode OPD are Iopd valley and Iopd ridge, respectively, then the detected valley fingerprint acquisition signal Spine fingerprint acquisition signal They can be satisfied separately: Formula (16); Formula (17); Combining formulas (16) and (17) above, the ridge and valley signals of the detected fingerprint can be determined. It can satisfy: Formula (18); Fingerprint detection can be achieved based on the above formula (18), thereby reliably identifying fingerprints.

[0119] It is understandable that, since the driving method of the fingerprint acquisition device can have the same technical effect as the fingerprint acquisition device described above, for the sake of brevity, the technical effect of the driving method of the fingerprint acquisition device will not be described again here.

[0120] This disclosure also provides a display device. For example... Figure 12 As shown, the display device includes: a display panel 10, and a fingerprint collection device 00 as described above.

[0121] Understandably, in combination Figure 8 and Figure 9 The photoelectric sensing circuit 02 and photoelectric sensor 01 in the fingerprint acquisition device 00 can be located in the display area AA in the panel area A1 of the display panel 10, and the fingerprint acquisition circuit 03 in the fingerprint acquisition device 00 can be located in the peripheral area BB and / or circuit area B1 in the panel area A1 of the display panel 10. Figure 12 This is merely an illustrative description of the display device, which includes a display panel 10 and a fingerprint collection device 00, but is not intended to define the positional relationship between the two.

[0122] Optionally, the display device can be an OLED display device, an active-matrix organic light-emitting diode (AMOLED) display device, etc. Among these, OLED display technology, benefiting from its high resolution and high contrast, has gained widespread market acceptance. Furthermore, the display device can also include any product or component with display functionality, such as mobile phones, tablets, flexible display devices, televisions, and monitors.

[0123] It is understandable that, since the display device can have essentially the same technical effect as the fingerprint collection device described above, for the sake of brevity, the technical effect of the display device will not be described again here.

[0124] It is understood that the terminology used in the embodiments of this disclosure is for illustrative purposes only and is not intended to limit the disclosure. Unless otherwise defined, the technical or scientific terms used in the implementation of this disclosure should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains.

[0125] For example, the terms "first," "second," or "third," and similar words used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. When we say that an element is "connected" or "linked" to another element, it can be directly connected or linked to other elements, or there may be intermediate elements. Furthermore, the use of "connected" or "linked" herein can include wireless connections or wireless links. Similarly, the terms "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including," etc., mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed after "comprising" or "including" and their equivalents, and do not exclude other elements or objects. "And / or" indicates that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. "Up," "down," "left," or "right" are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0126] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A fingerprint acquisition device, characterized by The fingerprint acquisition device includes: multiple photoelectric sensors, multiple photoelectric sensing circuits corresponding one-to-one with the multiple photoelectric sensors, and a fingerprint acquisition circuit. The photoelectric sensing circuit is connected to the reset control line, the reset power line, the sensing scan line, the sensing acquisition line, and the first pole of the corresponding photoelectric sensor, respectively. It is used to control the connection and disconnection between the reset power line and the first pole of the photoelectric sensor in response to the reset control signal provided by the reset control line, and to transmit signals through the sensing acquisition line in response to the sensing scan signal provided by the sensing scan line. The second pole of the photoelectric sensor is connected to the drive power line. The fingerprint acquisition circuit is connected to multiple sensing and acquisition lines that are connected to the multiple photoelectric sensing circuits, and is used to input a constant current to the multiple photoelectric sensing circuits through the multiple sensing and acquisition lines, and to acquire the fingerprint acquisition signals output by the multiple photoelectric sensing circuits through the multiple sensing and acquisition lines.

2. The fingerprint acquisition device of claim 1, wherein, The fingerprint acquisition circuit includes: a current supply unit and a signal acquisition unit; The current supply unit is connected to the plurality of sensing and acquisition lines and is used to input a constant current to the plurality of photoelectric sensing circuits through the plurality of sensing and acquisition lines; The signal acquisition unit is connected to the multiple sensing acquisition lines and is used to acquire the fingerprint acquisition signals output by the multiple photoelectric sensing circuits through the multiple sensing acquisition lines.

3. The fingerprint acquisition device of claim 2, wherein, The signal acquisition unit includes: a plurality of voltage followers corresponding one-to-one with the plurality of sensing acquisition lines; The positive input terminal of the voltage follower is connected to the sensing acquisition line, and the negative input terminal of the voltage follower is connected to the output terminal of the voltage follower.

4. The fingerprint acquisition device of claim 2, wherein, The current supply unit includes: a constant current source; One end of the constant current source is connected to the constant current power supply terminal, and the other end of the constant current source is connected to the multiple sensing and acquisition lines. The constant current source is used to output the constant current based on the power signal provided by the constant current power supply terminal.

5. The fingerprint acquisition device of claim 4, wherein, The constant current source is a mirror constant current source, and the mirror constant current source includes: a main current source and multiple auxiliary current sources corresponding one-to-one with the multiple sensing and acquisition lines. The main current source and the plurality of auxiliary current sources are all connected to the constant current power supply terminal, and the plurality of auxiliary current sources are also respectively connected to the main current source and the plurality of sensing and acquisition lines.

6. The fingerprint acquisition device of claim 5, wherein, The main current source and each of the auxiliary current sources have the same design parameters, so that the characteristic parameters of the main current source and each of the auxiliary current sources are the same, so as to generate multiple constant currents of the same magnitude.

7. The fingerprint acquisition device of claim 5, wherein, The main current source includes a first transistor; each of the auxiliary current sources includes a second transistor. The gate of the first transistor is connected to the second terminal of the first transistor, the gate of the second transistor is connected to the gate of the first transistor, the first terminal of the first transistor and the first terminal of the second transistor are both connected to the constant current power supply terminal, and the second terminal of the second transistor is connected to the sensing acquisition line.

8. The fingerprint acquisition device of claim 7, wherein, Each of the auxiliary current sources includes a second transistor that is centrally disposed on one side of the plurality of sensing and acquisition lines and is connected to the plurality of sensing and acquisition lines through sensing leads; Alternatively, each of the auxiliary current sources includes a second transistor that is independently disposed on one side of the connected sensing acquisition line.

9. The apparatus of claim 5, wherein, The fingerprint acquisition device further includes: a plurality of switching units corresponding one-to-one with the plurality of auxiliary current sources; Each of the switch units is connected between a corresponding auxiliary current source and a sensing acquisition line corresponding to the auxiliary current source, and is also connected to a switch control line, and is used to control the on / off state of the auxiliary current source and the sensing acquisition line in response to the switch control signal provided by the switch control line.

10. The fingerprint acquisition device of claim 9, wherein, Each of the switching units includes: a third transistor; The gate of the third transistor is connected to the switch control line, the first electrode of the third transistor is connected to the auxiliary current source, and the second electrode of the third transistor is connected to the sensing acquisition line.

11. The fingerprint acquisition device according to any of claims 2 to 10, characterized in that The fingerprint acquisition device is used in a display device, which includes: a panel area and a circuit area that are adjacent to each other; the panel area includes: a display area and a peripheral area that are adjacent to each other. The plurality of photoelectric sensors and the plurality of photoelectric sensing circuits are all located in the display area; The signal acquisition unit in the fingerprint acquisition circuit is located in the circuit area; The current supply unit in the fingerprint acquisition circuit is located in the circuit area and integrated with the signal acquisition unit; or, the current supply unit in the fingerprint acquisition circuit is located in the peripheral area.

12. The device according to any of claims 1 to 10, characterized in that, The plurality of photoelectric sensors and the plurality of photoelectric sensing circuits are arranged in an array; each photoelectric sensing circuit located in the same column is connected to the same sensing and acquisition line. The photoelectric sensing circuit includes: a reset sub-circuit, a drive sub-circuit, and a switch sub-circuit; The reset sub-circuit is connected to the reset control line, the reset power supply line, and the drive node respectively, and is used to control the on / off state of the reset power supply line and the drive node in response to the reset control signal. The drive node is connected to the first pole of the photoelectric sensor. The driving sub-circuit is connected to the driving node, the reset power line and the output node respectively, and is used to control the potential of the output node in response to the potential of the driving node and the reset power signal provided by the reset power line; The switching sub-circuit is connected to the sensing scan line, the output node, and the sensing acquisition line respectively, and is used to control the on / off state of the output node and the sensing acquisition line in response to the sensing scan signal.

13. The fingerprint acquisition device of claim 12, wherein, The reset sub-circuit includes a reset transistor; the driving sub-circuit includes a driving transistor; the switching sub-circuit includes a switching transistor; the photoelectric sensor includes an organic photodiode. The gate of the reset transistor is connected to the reset control line, the first terminal of the reset transistor is connected to the reset power supply line, and the second terminal of the reset transistor is connected to the drive node. The gate of the driving transistor is connected to the driving node, the first terminal of the driving transistor is connected to the reset power supply line, and the second terminal of the driving transistor is connected to the output node. The gate of the switching transistor is connected to the sensing scan line, the first electrode of the switching transistor is connected to the output node, and the second electrode of the switching transistor is connected to the sensing acquisition line. The anode of the organic photodiode is connected to the driving node as the first electrode of the photoelectric sensor, and the cathode of the organic photodiode is connected to the driving power line as the second electrode of the photoelectric sensor.

14. A driving method of a fingerprint acquisition device, characterized by, Applied in any one of the fingerprint acquisition devices as described in claims 1 to 13, the method comprises: In the first stage, the photoelectric sensing circuit responds to the reset control signal provided by the reset control line and controls the reset power line to conduct with the first pole of the photoelectric sensor. In the second stage, the fingerprint acquisition circuit provides a constant current to the photoelectric sensing circuit through the sensing acquisition line, and acquires the fingerprint acquisition signal first output by the photoelectric sensing circuit through the sensing acquisition line. In the third stage, the photoelectric sensing circuit responds to the reset control signal and controls the reset power line to disconnect from the first pole of the photoelectric sensor. In the fourth stage, the fingerprint acquisition circuit provides a constant current to the photoelectric sensing circuit through the sensing acquisition line, and acquires the fingerprint acquisition signal output by the photoelectric sensing circuit again through the sensing acquisition line.

15. A display device comprising: The display device includes: a display panel, and a fingerprint acquisition device as described in any one of claims 1 to 13.

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