WO2020038463A1 - 光学指纹识别电路 - Google Patents
光学指纹识别电路 Download PDFInfo
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- WO2020038463A1 WO2020038463A1 PCT/CN2019/102265 CN2019102265W WO2020038463A1 WO 2020038463 A1 WO2020038463 A1 WO 2020038463A1 CN 2019102265 W CN2019102265 W CN 2019102265W WO 2020038463 A1 WO2020038463 A1 WO 2020038463A1
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F18/00—Pattern recognition
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- the present application relates to the field of circuits, and more specifically, to an optical signal processing circuit and an optical fingerprint recognition system.
- Under-screen optical fingerprint recognition is becoming standard in current mobile phone products. Users can press their finger on a certain position on the screen to activate the fingerprint recognition function. Specifically, the light is generated by the light source under the screen to illuminate the finger. The reflected light of the finger carries fingerprint information and is received by the image sensor below the screen, generates a fingerprint image, and then extracts the fingerprint characteristics, which can be used to implement functions such as unlocking and payment. Thereby improving the security performance of the mobile phone.
- a large-area optical fingerprint sensor based on a thin film transistor (TFT) substrate can be used to collect and detect the reflected light of a fingerprint transmitted through the screen.
- TFT thin film transistor
- each pixel reading circuit that reads the reflected light of a fingerprint contains only one TFT transistor (which can be referred to as a 1T circuit), and the TFT transistor is used as a gating switch when reading a fingerprint signal.
- the light signal reflected by the fingerprint is weak, the signal to noise of the output signal of the fingerprint sensor is relatively low, and a high fingerprint recognition rate cannot be achieved.
- the present application provides an optical signal processing circuit and an electronic device, which are used to solve the problem of low fingerprint recognition rate existing in the prior art.
- an optical signal processing circuit including: a photosensitive device, an amplifying tube T 1 , a switching tube T 2 , a switching tube T 3 , a readout circuit, a control circuit, and a voltage adjustable power supply, wherein,
- the photosensitive device and connected to the gate of the amplification tube T 1, T between the gate and the drain pipe 1 is connected across said switch transistor T 2, a source of the amplifier tubes T connected by amplifying the The voltage adjustable power supply, a source or a drain of the amplifying tube T 1 is connected to the readout circuit through the switching tube T 3 , and the control circuit is connected to the switching tube T 2 and the switching tube T 3 Connected to the voltage adjustable power supply;
- the control circuit is used to control the optical signal processing circuit in a first state, wherein when the optical signal processing circuit is in the first state, the photosensitive device is not exposed, and when the control circuit is used to control When the optical signal processing circuit is in the first state, the control circuit is specifically configured to control the switch T 2 to be turned on, to control the voltage adjustable power supply to generate a compensation reset voltage, and to control the switch T 3 is turned off, so that the gate-source voltage Vgs of the amplifying tube T 1 is equal to the threshold voltage V T of the first TFT;
- the control circuit is further configured to control the optical signal processing circuit in a second state, where the second state is a state after the first state, and when the optical signal processing circuit is in the second state, The photosensitive device is exposed and generates an input voltage applied to the gate of the amplifying tube T 1 ; when the control circuit is used to control the optical signal processing circuit in the second state, the control circuit is specifically used Controlling the switching tube T 2 to be turned off, controlling the voltage adjustable power supply to be disconnected from the source of the amplifying tube T 1 , and controlling the switching tube T 3 to be turned off;
- the control circuit is further configured to control the optical signal processing circuit in a third state, where the third state is a state after the second state, and when the optical signal processing circuit is in the third state,
- the photosensitive device stops exposing; when the control circuit is used to control the optical signal processing circuit in the third state, the control circuit is specifically used to control the switch T 2 to be turned off and to control the switch
- the tube T 3 is turned on, so that the readout circuit obtains an output signal of the amplification tube T 1
- the control circuit is further specifically configured to control the voltage adjustable power supply to generate a read reference voltage so that the amplification
- the Vgs of the tube T 1 is the sum of the V T , the input voltage, and the voltage increment, wherein the voltage increment is a difference between the amplitude of the compensation reset voltage and the read reference voltage.
- the voltage increment is greater than 0V.
- the gate voltage of T 1 since the optical signal processing circuit is in the compensation and reset phase, the gate voltage of T 1 has just reached the level that turns on the amplifier tube T 1. Therefore, when the input voltage and voltage increase are applied to the gate of T 1 the amount, T gate-source voltage Vgs 1 becomes large, T. 1 will be the input voltage signal is amplified to produce an output signal.
- the adjustable voltage is connected to the source of the amplifying transistor T 1 so that the adjustable voltage is the compensation reset voltage during the compensation phase of T 1 , and the adjustable voltage is the read reference voltage during the reading phase of the fingerprint signal , So that when the gate of T 1 reads the fingerprint signal, the increase of the gate-source voltage Vgs is the sum of the input voltage and the voltage increase corresponding to the fingerprint signal.
- the voltage increment can further increase the gate-source voltage Vgs of T 1 , thereby further increasing the static operating point of the amplifier circuit, and further amplifying the input fingerprint signal. Therefore, the embodiment of the present application can achieve gain control on the amplifying transistor T 1 , improve the signal-to-noise ratio of the output signal of the fingerprint sensor, and improve the fingerprint recognition rate.
- the voltage adjustable power supply may include a selection circuit, a first power supply, and a second power supply, the first power supply is used to generate the compensation reset voltage, and the second power supply is used to The read reference voltage is generated.
- the selection circuit may be used to select that the first power source is connected to the source of the amplifier tube T 1 , and the second power source is not connected to the source of the amplifier tube T 1 .
- the selection circuit may select that the second power source is connected to the source of the amplifier tube T 1 , and the first power source is not connected to the source of the amplifier tube T 1 .
- the selection circuit may select that neither the first power source nor the second power source is connected to the source of the amplifier tube T 1 .
- the voltage adjustable power supply may include a voltage control circuit and an adjustable power supply, and the adjustable power supply may generate a voltage value with adjustable size.
- the voltage control circuit can adjust the voltage value generated by the adjustable power supply under the control of the control circuit, so as to compensate the reset voltage or read the reference voltage, or disconnect the adjustable power supply from the source of the amplifier tube T 1 , that is, The voltage adjustable power supply does not provide a voltage to the amplifying tube T 1 .
- the obtained output signal is an output current.
- the integration circuit is a relatively mature technology as a readout circuit. Therefore, based on this, the implementation is simple and the design cost is reduced.
- the amplifying tube T 1 is an N-type thin film transistor TFT, and a gate of the amplifying tube T 1 is connected to an anode of the photosensitive device.
- a drain of the amplifier tube T 1 is connected to the readout circuit through the switch tube T 3 ;
- the voltage adjustable power supply includes a switch tube T 4 , a switch tube T 5 , a first power source, and a second power source, wherein the switch tube T 4 is connected to the first power source, and the switch tube T 5 is connected to the first power source.
- a second power source connected, the first power source used to generate the compensation reset voltage, and the second power source used to generate the read reference voltage;
- the first power source is connected to the source of the amplifier tube T 1 ;
- the second power source is connected to the source of the amplifier tube T 1 ;
- the switching tube T 2 , the switching tube T 3 , the switching tube T 4 and the switching tube T 5 are all N-type TFTs. This solution can be implemented using the existing TFT process, which is simple to implement and reduces the design cost.
- the compensation reset voltage is -4.5V
- the read reference voltage is -6V.
- the amplifying tube T 1 is a P-type TFT, and a gate of the amplifying tube T 1 is connected to a cathode of the photosensitive device.
- a drain of the amplifier tube T 1 is connected to a bias power source through a switching tube T 6 , and an anode of a photosensitive device is connected to the bias power source, wherein, The bias power is used to generate a bias voltage;
- the voltage adjustable power supply includes a switching tube T 7 , the switching tube T 3 , a first power supply, and a second power supply, wherein the switching tube T 7 is connected to the first power supply, and the amplification tube T 1 the source of the switching transistor T 3 by connecting the readout circuit, wherein the readout circuit includes operational amplifier circuit, the operational amplifier circuit with the input terminal connected to said second power source, said first power supply For generating the compensation reset voltage, the second power supply is used for generating the read reference voltage;
- the first power source is connected to the source of the amplifier tube T 1 ;
- the second power source is connected to the source of the amplifier tube T 1 ;
- the switching tube T 2 , the switching tube T 3 , the switching tube T 6 and the switching tube T 7 are all P-type TFTs.
- the compensation reset voltage is -1V
- the read reference voltage is -0.6V
- the photosensitive device is a photodiode or an organic photodetector.
- an optical signal processing system including at least two lines of the optical signal processing circuit in the first aspect and any possible implementation of the first aspect, each of the at least two lines including at least one of the An optical signal processing circuit, wherein the at least two rows of optical signal processing circuits share a control circuit;
- the common control circuit is configured to input a same control signal to the first line of optical signal processing circuits in the at least two lines and the second line of optical signal processing circuits in the at least two lines, and the control signals are used to control
- the first-row optical signal processing circuit is in the first state
- the second-row optical signal processing circuit is in the third state.
- the light processing circuit of the previous line that has been read is compensated and reset at the same time, and the exposure of the next frame is ready to be started, thereby realizing reading and compensation reset.
- the operation is completed in one scan.
- an electronic device including the optical signal processing system, panel, display module, and processor, or other modules or units according to the second aspect, wherein the optical signal processing system is provided in The panel, the display module is used to provide lighting for the optical signal processing circuit, and the processor is configured to process an output signal output by the optical signal processing system.
- FIG. 1 shows a frame diagram of a fingerprint collection system according to an embodiment of the present application
- FIG. 2 is a schematic diagram of an optical signal processing circuit according to an embodiment of the present application.
- FIG. 3 is a schematic diagram of an optical signal processing circuit according to an embodiment of the present application.
- FIG. 4 is a schematic diagram of scan1 and scan2 when the optical signal processing circuit according to the embodiment of the present application is operating;
- FIG. 5 is a schematic diagram of an optical signal processing circuit according to an embodiment of the present application.
- FIG. 6 is a schematic diagram of scan1 and scan2 when the optical signal processing circuit according to the embodiment of the present application is operating;
- FIG. 7 shows a partial schematic diagram of a fingerprint sensor according to an embodiment of the present application.
- FIG. 1 shows a frame diagram of a fingerprint collection system provided by an embodiment of the present application.
- the fingerprint collection system in the embodiment of the present application can be used for under-screen fingerprint detection of terminal devices such as mobile phones and tablets.
- the fingerprint collection system includes a TFT panel 101, a gate driver (GOA) 102 on the array, an active pixel sensor (APS) 103, an analog front end (AFE) 104, and a field Programmable gate array / microcontroller unit 105, application processor 106, and display module 107.
- GOA gate driver
- APS active pixel sensor
- AFE analog front end
- the TFT panel 101 is the panel where the fingerprint sensor is located, and its side is GOA 102, which is used for sequential gating of row selection lines.
- the fingerprint sensor includes a pixel sensor array including an APS 103 corresponding to each pixel.
- the AFE 104 is used to collect a fingerprint signal detected by the TFT panel 101.
- the fingerprint signal is an analog signal and outputs a corresponding digital signal.
- the FPGA / MCU 105 is used to control the timing of the AFE 104 and the GOA, and performs interface conversion on the fingerprint data of the AFE 104, and sends the converted fingerprint data to the application processor 106 for feature extraction and comparison processing.
- the display module 107 includes self-emitting pixels, such as organic light-emitting diodes (OLEDs), which can provide illumination for fingerprint collection.
- OLEDs organic light-emitting diodes
- FIG. 2 shows a schematic diagram of an optical signal processing circuit provided by an embodiment of the present application.
- the optical signal processing circuit includes: a photosensitive device 201 (such as a photo diode (PD), an organic photodetector (OPD) )), The amplification tube T 1 , the switching tube T 2 , the switching tube T 3 , the readout circuit 202, the control circuit 203, and the voltage adjustable power supply 204.
- the photosensitive device 201 is connected to the gate of T 1, T 2 bridging between the gate and drain of T 1, T 1 is connected to the source voltage adjustable power supply 204, a source or drain T 1 through T 3 connected to a readout circuit 202, control circuit 203 and T, T 3 and said adjustable voltage power supply 2 is connected.
- T 1 is used to amplify the input fingerprint signal.
- T 2 is connected between the gate and drain of T 1 , that is, the input and output of T 2 are connected to the gate and drain of T 1 respectively, and the control end of T 2 is connected to control circuit 203 T 2 is closed or opened under the control of the control circuit.
- control circuit 203 is, for example, GOA 102 in FIG. 1, and can generate a compensation reset control signal and a read control signal.
- the following description uses the compensation reset control signal as the first scan signal (scan1) and the read control signal as the second scan signal (scan1) as an example, but this does not limit the embodiment of the present application.
- control signal output by the control circuit 203 may control the optical signal processing circuit to be in a compensation reset phase, an exposure phase, and a reading phase.
- the optical signal processing circuit can perform the above-mentioned work flow under the control of scan1 and scan2 to read the fingerprint signal.
- the three phases in the workflow may also have other command modes, such as the compensation reset phase, the exposure phase, and the read phase, which may be referred to as the first state, the second state, and the third state in sequence. The example does not limit this.
- control circuit is configured to control the optical signal processing circuit in a compensation reset stage, wherein when the optical signal processing circuit is in the compensation reset stage, the photosensitive device is not exposed, and when the control circuit For controlling the optical signal processing circuit in the compensation reset stage, the control circuit is specifically configured to control the switch T 2 to be turned on, control the voltage adjustable power supply to generate a compensation reset voltage, and control the The switching tube T 3 is turned off, so that the gate-source voltage Vgs of the amplifying tube T 1 is equal to the threshold voltage V T of the first TFT.
- the control circuit is further configured to control the optical signal processing circuit to be in an exposure phase, where the exposure phase is a phase after the compensation reset phase, and when the optical signal processing circuit is in the exposure phase, the light sensitive
- the device exposes and generates an input voltage applied to the gate of the amplifying tube T 1 ; when the control circuit is used to control the optical signal processing circuit in the exposure phase, the control circuit is specifically used to control the
- the switching tube T 2 is turned off, the voltage adjustable power source is controlled to be disconnected from the source of the amplifier tube T 1 , and the switching tube T 3 is controlled to be turned off. “Disconnected” here means that the voltage adjustable power supply does not provide voltage to the amplifier tube T 1 .
- the control circuit is further configured to control the optical signal processing circuit in a reading phase, where the reading phase is a phase after the first exposure phase, and when the optical signal processing circuit is in the exposure phase, all the The photosensitive device stops exposing; when the control circuit is used to control the optical signal processing circuit in the exposure phase, the control circuit is specifically configured to control the switch T 2 to be turned off and to control the switch T 3 is turned on to control the voltage adjustable power supply to generate a read reference voltage, so that Vgs of the amplifying tube T 1 is a sum of the V T , the input voltage, and a voltage increase, wherein the voltage increase the difference between the reset voltage to compensate the magnitude of the read reference voltage, such that the readout circuit obtaining said amplified output signal T 1 as a tube.
- the obtained output signal is an output current.
- the optical signal processing circuit After the gate voltage of T 1 reaches a level at which the amplifying tube T 1 is turned on, the optical signal processing circuit is in an exposure phase. In the exposure phase, SCAN1 OFF control T 2, T 3 and disconnect the control scan2, SCAN1 and / or control scan2 T 1 as the source and the adjustable voltage is disconnected. That is, after the gate voltage of T 1 reaches a level at which the amplifying tube T 1 is turned on, the photosensitive device 201 is exposed, and at this time, the photosensitive device obtains a fingerprint light signal. The photosensitive device then performs photoelectric conversion on the optical signal to generate a charge, so that the voltage at the place where the photosensitive device 201 is connected to the gate of the amplification tube T 1 changes. That is, the photosensitive device producing an input voltage after exposure, the input voltage applied to the gate T 1, ie.
- the optical signal processing circuit After the exposure of the photosensitive device 201, the optical signal processing circuit enters a reading stage. Specifically, scan1 controls T 2 to be turned off, and scan 2 controls T 3 to be turned on, so as to read the fingerprint signal (that is, the output current of T 1 ) by the readout circuit 202.
- scan1 and / or scan2 controls the voltage adjustable power supply to generate a read reference voltage.
- the Vgs of the first TFT is the sum of the V T , the input voltage, and the voltage increase, where the voltage increase is used to make Vgs larger, so that the output signal is also larger.
- the positive or negative level the voltage increase can also use the positive or negative level accordingly.
- the voltage increment is specifically the difference between the amplitude of the compensation reset voltage and the read reference voltage. the readout circuitry can obtain larger output signal of the amplification tube T 1.
- the gate voltage of T 1 Since the optical signal processing circuit is reset when the compensation phase, the gate voltage of T 1 has just reached the level of the amplification tube T 1 is turned on, so when the gate T 1 reapplication of the input voltage and the voltage increment, T 1 The gate-source voltage Vgs will increase, and T 1 will amplify the input voltage signal to generate an output signal.
- the voltage can be adjusted such that compensation stage T 1 is reset voltage compensation, in the reading stage may be adjusted so that the fingerprint signal voltage is read reference voltage , So that when the gate of T 1 reads the fingerprint signal, the increase of the gate-source voltage Vgs is the sum of the input voltage and the voltage increase corresponding to the fingerprint signal.
- the voltage increment can further increase the gate-source voltage Vgs of T 1 , thereby further increasing the static operating point of the amplifier circuit, and further amplifying the input fingerprint signal. Therefore, the embodiment of the present application can achieve gain control on the amplifying transistor T 1 , improve the signal-to-noise ratio of the output signal of the fingerprint sensor, and improve the fingerprint recognition rate.
- the value range of the voltage increment is greater than 0V, so that during the reading phase of the signal processing circuit, Vgs is greater than Vt and the sum of the input voltage due to the exposure of the photosensitive device.
- gain control of T 1 is achieved by controlling the voltage difference between the reset voltage and the read reference voltage.
- the voltage adjustable power supply may include a selection circuit, a first power supply, and a second power supply, the first power supply is used to generate the compensation reset voltage, and the second power supply is used to The read reference voltage is generated.
- the selection circuit may be used to select that the first power source is connected to the source of the amplifier tube T 1 , and the second power source is not connected to the source of the amplifier tube T 1 .
- the selection circuit may select that the second power source is connected to the source of the amplifier tube T 1 , and the first power source is not connected to the source of the amplifier tube T 1 .
- the selection circuit may select that neither the first power source nor the second power source is connected to the source of the amplifier tube T 1 .
- the selection circuit may also be called a switching circuit or another name, which is not limited in the embodiment of the present application.
- the voltage adjustable power supply may include a voltage control circuit and an adjustable power supply, and the adjustable power supply may generate a voltage value with adjustable size.
- the voltage control circuit can adjust the voltage value generated by the adjustable power supply under the control of the control circuit, so that the voltage value can be used to compensate the reset voltage or read the reference voltage as required, or make the adjustable power supply and the source of the amplifier tube T 1 as required . The pole is disconnected.
- T 1 is an N-type TFT, and the gate of T 1 is connected to the anode of the photosensitive device 201.
- the drain of the amplifying tube T 1 is connected to the readout circuit through the switching tube T 3 ;
- the voltage adjustable power supply includes a switching tube T 4 , a switching tube T 5 , a first power source, and a second The power source, wherein the switching tube T 4 is connected to the first power source, the switching tube T 5 is connected to the second power source, the first power source is used to generate the compensation reset voltage, and the second A power source is used to generate the read reference voltage.
- the first power source is connected to the source of the amplification tube T 1 ; when the control circuit controls the When the switching tube T 4 is turned off and the switching tube T 5 is turned on, the second power source is connected to the source of the amplifier tube T 1 ; when the control circuit controls the switching tube T 4 to be turned off, When the switching tube T 5 is turned off, neither the first power source nor the second power source is connected to the source of the amplifier tube T 1 .
- FIG. 3 shows a schematic diagram of an optional optical signal processing circuit provided by an embodiment of the present application.
- a photo sensor is used as an example of PD.
- T 1 is an N-type TFT
- the anode of PD is connected to the gate of T 1
- the cathode of PD is grounded (GND)
- the drain of T 1 is connected to the readout circuit through T 3
- the source of T 1 is connected to switch T 4
- the source of T 1 is also connected to the read reference voltage through the switch T 5 .
- the read reference voltage is a bias voltage Vbias.
- FIG. 3 only shows each voltage value by way of example, and does not show a power source for generating each voltage, but this does not limit the embodiment of the present application.
- the source of T 1 when T 4 is turned on and T 5 is turned off, the source of T 1 is connected to an adjustable voltage and the adjustable voltage is equal to the compensation reset voltage V DD ; when T 4 is turned off, T 5 is turned on At this time, the source of T 1 is connected to an adjustable voltage and the adjustable voltage is equal to the read reference voltage Vbias.
- T 1 , T 2 , T 3 , T 4 , and T 5 are all N-type TFTs.
- scan1 is input to the gates of T 2 and T 4
- scan2 is input to T 3 , T 5 gate.
- scan1 is high and scan2 is low
- T 2 and T 4 are on and T 3 and T 5 are off.
- scan1 and scan2 are both low, T 2 , T 3 , T 4 , T 5 Both are turned off; when scan1 is low and scan2 is high, T 2 and T 4 are turned off and T 3 and T 5 are turned on.
- the compensation reset voltage V DD may be set to -4.5V, and the read reference voltage Vbias may be set to -6V. It can be understood that in the embodiment of the present application, the compensation reset voltage V DD and the read reference voltage Vbias can also be set to other voltage values, so that T 1 amplifies the input fingerprint signal (that is, the input voltage). Not specifically limited.
- FIG. 4 is a schematic diagram of scan1 and scan2 during the operation of the optical signal processing circuit according to the embodiment of the present application. Specifically, when the optical signal processing circuit reads data in the previous frame, scan1 is low and scan2 is high. At this time, T 3 and T 5 are closed (that is, conducting), and T 2 and T 4 are open (that is, disconnect). Then, the optical signal processing circuit enters the compensation reset stage, scan1 becomes high, and scan2 becomes low. At this time, T 2 and T 4 are closed (that is, on), and T 3 and T 5 are open (that is, open). Because the gate and drain of T 1 are short-circuited, Vgs drops to a threshold voltage V T equal to T 1.
- the optical signal processing circuit enters the exposure phase, scan2 are low and SCAN1, T 2, T 3, T 4, T 5 are turned off, because the PD photosensitive, its anode voltage will rise.
- scan2 are low and SCAN1, T 2, T 3, T 4, T 5 are turned off, because the PD photosensitive, its anode voltage will rise.
- Scan1 is low and scan2 is high.
- T 3 and T 5 are closed (ie, conducting), and T 2 and T 4 are open (ie OFF), at this time T 1 enters the amplified state under the condition of bias, and the read-out circuit can read the amplified signal.
- the source voltage of T 1 changes from V DD at reset to lower Vbias, which is equivalent to increasing the amplitude of the input signal (increments of V DD -Vbias), that is, this
- Vgs V T + (V DD -Vbias)
- the output amplitude of the amplified signal can be increased, the signal-to-noise ratio of the signal read by the reading circuit can be improved, and the fingerprint recognition rate can be improved.
- the next frame of data can be read, that is, scan1 is high, scan2 is low, and the compensation reset phase of the next frame is entered.
- T 1 enters an amplified state, which means that T 1 can amplify an input signal.
- T 1 may be in a variable resistance region or a saturation region. This is not limited.
- T 1 is a P-type TFT, and the gate of T 1 is connected to the cathode of the photosensitive device 201.
- the drain of the amplifying tube T 1 is connected to a bias power source through a switching tube T 6 , and the anode of the photosensitive device is connected to the bias power source, wherein the bias power source is used to generate a bias voltage;
- the voltage adjustable power supply includes a switching tube T 7 , the switching tube T 3 , a first power supply, and a second power supply, wherein the switching tube T 7 is connected to the first power supply, and the amplification tube T 1 the source of the switching transistor T 3 by connecting the readout circuit, wherein the readout circuit includes operational amplifier circuit, the operational amplifier circuit with the input terminal connected to said second power source, said first power supply For generating the compensation reset voltage, the second power supply is used to generate the read reference voltage.
- the control circuit controls the switching tube T 7 to be turned on and the switching tube T 3 to be turned off
- the first power source is connected to the source of the amplifier tube T 1 ;
- the control circuit controls the When the switching tube T 7 is turned off and the switching tube T 3 is turned on, the second power source is connected to the source of the amplifier tube T 1 ;
- the control circuit controls the switching tube T 7 to be turned off, When the switching tube T 3 is turned off, neither the first power source nor the second power source is connected to the source of the amplifier tube T 1 .
- FIG. 5 shows a schematic diagram of an optional optical signal processing circuit provided by an embodiment of the present application.
- the photosensitive device is a PD as an example.
- T 1 is a P-type TFTMOS transistor
- the cathode of PD is connected to the gate of T 1
- the anode is connected to the bias voltage Vbias
- the drain of T 1 is connected to the bias voltage Vbias through the switch T 6
- the source of T 1 is also
- the switch T 7 is connected to the compensation reset voltage V DD
- the source of T 1 is connected to the readout circuit through T 3.
- the readout circuit includes an operational amplifier circuit, and the non-inverting input terminal of the operational amplifier circuit is connected to the readout circuit. Reference voltage.
- the read reference voltage is, for example, Vref. It should be noted that FIG. 5 only shows each voltage value by way of example, and does not show a power source for generating each voltage, but this does not limit the embodiment of the present application.
- the source of T 1 when T 7 is turned on and T 3 is turned off, the source of T 1 is connected to an adjustable voltage and the adjustable voltage is equal to the compensation reset voltage V DD ; when T 7 is turned off, T 3 is turned on At this time, the source of T 1 is connected to an adjustable voltage and the adjustable voltage is equal to the read reference voltage Vref.
- T 1 , T 2 , T 3 , T 6 , and T 7 are all P-type TFTs.
- scan1 is input to the gates of T 2 and T 7
- scan2 is input to T 3 , T 6 gate.
- scan1 is high and scan2 is low
- T 2 and T 7 are on and T 3 and T 6 are off.
- scan1 and scan2 are both low, T 2 , T 3 , T 6 , T 7 Both are turned off; when scan1 is low and scan2 is high, T 2 and T 7 are turned off and T 3 and T 6 are turned on.
- the compensation reset voltage V DD may be set to -1V
- the read reference voltage Vref may be set to -0.6V
- the bias voltage Vbias may be set to -6V.
- the compensation reset voltage V DD , the read reference voltage Vref, and the bias voltage Vbias can also be set to other voltage values, so that T 1 amplifies the input fingerprint signal (that is, the input voltage). The application example does not specifically limit this.
- FIG. 6 is a schematic diagram of scan1 and scan2 when the optical signal processing circuit according to the embodiment of the present application is operating. Specifically, when the optical signal processing circuit reads data in the previous frame, scan1 is high and scan2 is low. At this time, T 3 and T 6 are closed (that is, conductive), and T 2 and T 7 are open (that is, disconnect). Then, the optical signal processing circuit enters the compensation reset stage, scan1 becomes low, and scan2 becomes high. At this time, T 2 and T 7 are closed (that is, turned on), and T 3 and T 6 are opened (that is, opened). As the gate and drain of T 1 are short-circuited, Vgs rises to a threshold voltage V T equal to T 1.
- the cathode voltage of PD is maintained at Vbias + V T. Then, the optical signal processing circuit enters the exposure phase, scan2 are high and SCAN1, T 2, T 3, T 6, T 7 are turned off, because the PD photosensitive its cathode voltage will drop.
- scan2 are high and SCAN1, T 2, T 3, T 6, T 7 are turned off, because the PD photosensitive its cathode voltage will drop.
- Scan1 is high and scan2 is low.
- T 3 and T 6 are closed (that is, conductive), and T 2 and T 7 are open (that is, OFF), at this time T 1 enters the amplified state under the condition of bias, and the read-out circuit can read the amplified signal.
- the source voltage of T 1 changes from V DD at reset to a higher Vref, which is equivalent to increasing the amplitude of the input signal (increments of Vref-V DD ), that is, this
- Vgs V T + (Vbias-V DD )
- the output amplitude of the amplified signal can be increased, the signal-to-noise ratio of the signal read by the reading circuit can be improved, and the fingerprint recognition rate can be improved.
- the next frame of data can be read, that is, scan1 is low level and scan2 is high level, and the compensation reset phase of the next frame is entered.
- the N-type TFT may use an NMOS process
- the P-type TFT may use a PMOS process
- the amplifying tube or the switching tube may also be other types of transistors.
- the embodiment of the present application only describes the TFT as an example, but this does not limit the technical solution of the embodiment of the present application.
- the embodiment of the present application further provides an optical signal processing circuit, which may include at least two lines of the optical signal processing circuit in the above embodiment, and each of the at least two lines of the optical signal processing circuit includes at least one optical signal.
- the processing circuit wherein the at least two rows of optical signal processing circuits share a control circuit.
- the common control circuit is configured to input a same control signal to the first line of optical signal processing circuits in the at least two lines and the second line of optical signal processing circuits in the at least two lines, and the control signals are used to control
- the first row of optical signal processing circuits is in the compensation reset stage, and the second row of pixel processing circuits is in the reading stage. That is, the same control signal can simultaneously control one optical signal processing circuit in the compensation reset phase and the other optical signal processing circuit in the reading phase.
- the fingerprint sensor that is, the pixel sensor array may include at least two rows of optical signal processing circuits, and each row of the optical signal processing circuits includes at least one optical signal processing circuit as described above.
- the control circuit includes at least two grid lines, and each grid line inputs a compensation reset control signal (such as scan1) to each row of optical signal processing circuits, and simultaneously inputs a read signal to a row of optical signal processing circuits of the row of optical signal processing circuits. Take the control signal (such as scan2). In other words, one grid line is connected to two rows of optical signal processing circuits at the same time.
- the control signal provided by the grid line can be used as a compensation reset control signal for one row of optical signal processing circuits, and can also be used as a signal for the other row of optical signal processing circuits. Read the control signal.
- FIG. 7 shows a partial schematic diagram of a fingerprint sensor according to an embodiment of the present application.
- the fingerprint sensor includes at least two lines of APS, and each line of APS includes at least one APS.
- FIG. 7 shows only three lines of APS, and each line of APS includes 2 APS.
- the first line of APS includes APS1 and APS. 4.
- the second row of APS includes APS 2 and APS 5.
- only gate line 2 and gate line 3 are shown in FIG. 7 and two data Data (line).
- the gate line 2 provides scan1 signals for APS1 and APS4 in the first row, and provides scan2 signals for APS2 and APS5 in the second row.
- the gate line 3 provides scan1 signals for APS 2 and APS 5 in the second row, and provides scan2 signals for APS 3 and APS 6 in the third row.
- the output end of each column of APS is connected to the same data line.
- the output ends of APS1, APS2, APS3 are connected to the same data line
- the output ends of APS4, APS5, APS6 are connected to the same data line.
- the APS that has completed reading in the previous line is compensated and reset, and the exposure of the next frame is ready to be started, thereby realizing the reading and compensation reset operations. This is done in one scan.
- An embodiment of the present application further provides a fingerprint recognition system, and the fingerprint recognition system includes any possible optical signal processing circuit in the embodiments of the present application.
- An embodiment of the present application further provides an electronic device, which includes any one of the possible optical signal processing systems, panels, display modules, and processors, and / or other modules / units in the embodiments of the present application, where:
- the optical signal processing system is disposed on the panel
- the display module is configured to provide illumination for the optical signal processing circuit
- the processor is configured to process an output signal output by the optical signal processing circuit.
- the disclosed systems, devices, and methods may be implemented in other ways.
- the device embodiments described above are only schematic.
- the division of the unit is only a logical function division.
- multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not implemented.
- the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, which may be electrical, mechanical or other forms.
- the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objective of the solution of this embodiment.
- each functional unit in each embodiment of the present application may be integrated into one processing unit, or each of the units may exist separately physically, or two or more units may be integrated into one unit.
- the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.
- the technical solution of this application is essentially a part that contributes to the existing technology or a part of the technical solution can be embodied in the form of a software product.
- the computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in the embodiments of the present application.
- the aforementioned storage media include: U disks, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks or compact discs and other media that can store program codes .
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Abstract
本申请提供一种光信号处理电路和电子设备,能够提高指纹传感器输出信号的信噪比,进而提高指纹识别率。其中光信号处理电路包括:光敏器件,放大管T1,开关管T2,开关管T3,读出电路,控制电路和电压可调电源。由于光信号处理电路在补偿复位阶段时,T1的栅极电压刚刚达到使放大管T1开启的电平,因此当T1的栅极再施加该输入电压和电压增量时,T1的栅源电压Vgs将变大,T1将对输入电压信号进行放大,产生输出信号。
Description
本申请要求于2018年8月24日提交中国专利局、申请号为201810972261.8、申请名称为“传感器信号放大电路和电子设备”的中国专利申请的优先权,同时,要求于2019年1月4日提交中国专利局、申请号为201910008178.3、申请名称为“光学指纹识别电路”的中国专利申请的优先权,其全部内容通过引用结合在本申请中。
本申请涉及电路领域,并且更具体的,涉及光信号处理电路及光学指纹识别***。
屏下光学指纹识别正在成为目前手机产品的标配,用户将手指按压在屏幕上的某个位置,就能启动指纹识别功能。具体而言,通过屏下的光源产生光线照射手指,手指的反射光携带了指纹信息被屏幕下方的图像传感器接收,并产生指纹图像,然后提取指纹特征,可以用来实现解锁、支付等功能,从而提高手机的安全性能。
现有技术的一种指纹识别的方案中,可以基于薄膜晶体管(thin film transistor,TFT)基板的大面积光学指纹传感器,对透过屏幕的指纹反射光进行采集和检测。在该光学指纹传感器中,读取指纹反射光的每个像素读取电路仅包含一个TFT晶体管(可以称之为1T电路),该TFT晶体管用于指纹信号读取时的选通开关。当指纹反射光信号微弱时,该指纹传感器输出信号信噪比较低,无法实现较高的指纹识别率。
因此,亟需在指纹反射光信号微弱的情况下,提高指纹传感器输出信号信噪比,进而提高指纹识别率。
发明内容
本申请提供光信号处理电路和电子设备,用于解决现有技术存在着的指纹识别率低的问题。
第一方面,提供了一种光信号处理电路,包括:光敏器件,放大管T
1,开关管T
2,开关管T
3,读出电路,控制电路和电压可调电源,其中,
所述光敏器件与所述放大管T
1的栅极连接,所述放大管T
1的栅极和漏极之间跨接所述开关管T
2,所述放大管T
1的源极连接所述电压可调电源,所述放大管T
1的源极或漏极通过所述开关管T
3连接所述读出电路,所述控制电路与所述开关管T
2、所述开关管T
3和所述电压可调电源连接;
所述控制电路用于控制所述光信号处理电路处于第一状态,其中,当所述光信号处理电路处于所述第一状态时,所述光敏器件没有曝光,当所述控制电路用于控制所述光信号处理电路处于所述第一状态时,所述控制电路具体用于控制所述开关管T
2导通,控制所述电压可调电源产生补偿复位电压,以及控制所述开关管T
3断开,以使得所述放大管T
1 的栅源电压Vgs等于所述第一TFT的阈值电压V
T;
所述控制电路还用于控制所述光信号处理电路处于第二状态,所述第二状态是所述第一状态之后的一个状态,当所述光信号处理电路处于所述第二状态时,所述光敏器件曝光并产生施加到所述放大管T
1的栅极的输入电压;当所述控制电路用于控制所述光信号处理电路处于所述第二状态时,所述控制电路具体用于控制所述开关管T
2断开,控制所述电压可调电源与所述放大管T
1的源极断开,且控制所述开关管T3断开;
所述控制电路还用于控制所述光信号处理电路处于第三状态,所述第三状态是所述第二状态之后的一个状态,当所述光信号处理电路处于所述第三状态时,所述光敏器件停止曝光;当所述控制电路用于控制所述光信号处理电路处于所述第三状态时,所述控制电路具体用于控制所述开关管T
2断开,控制所述开关管T
3导通,从而使得所述读出电路获取所述放大管T
1的输出信号,所述控制电路还具体用于控制所述电压可调电源产生读取参考电压,以使得所述放大管T
1的Vgs为所述V
T、所述输入电压和电压增量之和,其中所述电压增量为所述补偿复位电压与所述读取参考电压的幅值之差。所述电压增量大于0V。
本申请实施例中,由于光信号处理电路在补偿复位阶段时,T
1的栅极电压刚刚达到使放大管T
1开启的电平,因此当T
1的栅极再施加该输入电压和电压增量时,T
1的栅源电压Vgs将变大,T
1将对输入电压信号进行放大,产生输出信号。
并且,本申请实施例通过放大晶体管T
1的源极连接可调节电压,在T
1的补偿阶段使得可调节电压为补偿复位电压,在指纹信号的读取阶段使得可调节电压为读取参考电压,使得T
1的栅极在读取指纹信号时,栅源电压Vgs的增加量为指纹信号对应的输入电压和电压增量之和。本申请实施例中,电压增量能够使得T
1的栅源电压Vgs进一步增大,进而提高放大电路的静态工作点,实现对输入指纹信号的进一步放大。因此本申请实施例能够实现对放大晶体管T
1的增益控制,提高指纹传感器输出信号信噪比,提高指纹识别率。
可选的,本申请实施例中,所述电压可调电源可以包括选择电路、第一电源和第二电源,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压。
其中,选择电路可以用于选择所述第一电源与所述放大管T
1的源极连接,第二电源不与所述放大管T
1的源极连接。或者,选择电路可以选择所述第二电源与所述放大管T
1的源极连接,第一电源不与所述放大管T
1的源极连接。或者选择电路可以选择所述第一电源和所述第二电源均不与所述放大管T
1的源极连接。该方案为一种实现方式,方便实现,降低了设计成本。
可选的,本申请实施例中,电压可调电源中可以包括电压控制电路和可调节电源,可调节电源可以产生可以调节大小的电压值。其中,电压控制电路可以在控制电路的控制下调节可调节电源产生的电压值,使其为补偿复位电压或读取参考电压,或者使可调节电源与放大管T
1的源极断开,即电压可调电源不向放大管T
1提供电压。该方案为一种实现方式,方便实现,降低了设计成本。
可选的,本申请实施例中,当读出电路是基于积分电路时,获取的输出信号为输出电流。积分电路作为读出电路是比较成熟的技术,因此,基于这个实现简单,降低了设计成本。
结合第一方面,在第一方面的某些实现方式中,所述放大管T
1为N型薄膜晶体管TFT,所述放大管T
1的栅极与所述光敏器件的阳极连接。
结合第一方面,在第一方面的某些实现方式中,,所述放大管T
1的漏极通过所述开关管T
3连接所述读出电路;
所述电压可调电源包括开关管T
4、开关管T
5、第一电源和第二电源,其中,所述开关管T
4与所述第一电源连接,所述开关管T
5与所述第二电源连接,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压;
当所述控制电路控制所述开关管T
4导通、所述开关管T
5断开时,所述第一电源与所述放大管T
1的源极连接;
当所述控制电路控制所述开关管T
4断开、所述开关管T
5导通时,所述第二电源与所述放大管T
1的源极连接;
当所述控制电路控制所述开关管T
4断开、所述开关管T
5断开时,所述第一电源和所述第二电源均不与所述放大管T
1的源极连接。
结合第一方面,在第一方面的某些实现方式中,所述开关管T
2、所述开关管T
3、所述开关管T
4和所述开关管T
5均为N型TFT。该方案可以采用现有的TFT工艺来实现,实现简单,降低了设计成本。
结合第一方面,在第一方面的某些实现方式中,所述补偿复位电压为-4.5V,所述读取参考电压为-6V。该两种电压为容易获取的电压,因此,实现简单,降低了设计成本。
结合第一方面,在第一方面的某些实现方式中,所述放大管T
1为P型TFT,所述放大管T
1的栅极与所述光敏器件的阴极连接。
结合第一方面,在第一方面的某些实现方式中,所述放大管T
1的漏极通过开关管T
6连接至偏置电源,光敏器件的阳极连接到所述偏置电源,其中,所述偏置电源用于产生偏置电压;
所述电压可调电源包括开关管T
7、所述开关管T
3、第一电源和第二电源,其中,所述开关管T
7与所述第一电源连接,所述放大管T
1的源极通过所述开关管T
3连接所述读出电路,其中,所述读出电路包括运放电路,所述运放电路的同相输入端连接所述第二电源,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压;
当所述控制电路控制所述开关管T
7导通、所述开关管T
3断开时,所述第一电源与所述放大管T
1的源极连接;
当所述控制电路控制所述开关管T
7断开、所述开关管T
3导通时,所述第二电源与所述放大管T
1的源极连接;
当所述控制电路控制所述开关管T
7断开、所述开关管T
3断开时,所述第一电源和所述第二电源均不与所述放大管T
1的源极连接。
结合第一方面,在第一方面的某些实现方式中,所述开关管T
2、所述开关管T
3、所述开关管T
6和所述开关管T
7均为P型TFT。
结合第一方面,在第一方面的某些实现方式中,所述补偿复位电压为-1V,所述读取参考电压为-0.6V。
可选的,所述光敏器件为光敏二极管,或者有机光电探测器。
第二方面,提供了一种光信号处理***,包括至少两行第一方面以及第一方面任意可能的实现方式中的光信号处理电路,所述至少两行中的每一行包括至少一个所述光信号处理电路,其中所述至少两行光信号处理电路共用控制电路;
其中,所述共用控制电路用于向所述至少两行中的第一行光信号处理电路和所述至少两行中第二行光信号处理电路输入同一控制信号,所述控制信号用于控制第一行光信号处理电路在处于所述第一状态,且所述第二行光信号处理电路处于所述第三状态。
因此,本申请实施例可以实现在读取当前行的指纹信号时,同时对上一行已完成读取的光处理电路进行补偿复位,准备开始下一帧的曝光,从而实现了读取、补偿复位操作在一次扫描的过程中一并完成。
第三方面,提供了一种电子设备,包括如第二方面所述的光信号处理***、面板、显示屏模组和处理器,或者其他模块或单元,其中,所述光信号处理***设置于所述面板,所述显示屏模组用于为所述光信号处理电路提供照明,所述处理器用于对所述光信号处理***输出的输出信号进行处理。
图1示出了本申请实施例提供的一种指纹采集***的框架图;
图2示出了本申请实施例提供的一种光信号处理电路的示意图;
图3示出了本申请实施例提供的一种光信号处理电路的示意图;
图4示出了本申请实施例光信号处理电路工作时的scan1和scan2的示意图;
图5示出了本申请实施例提供的一种光信号处理电路的示意图;
图6示出了本申请实施例光信号处理电路工作时的scan1和scan2的示意图;
图7示出了本申请实施例提供的一种指纹传感器的部分示意图。
下面将结合附图,对本申请中的技术方案进行描述。
图1示出了本申请实施例提供的一种指纹采集***的框架图。本申请实施例的指纹采集***可以用于手机、平板等终端设备的屏下指纹检测。该指纹采集***包括TFT面板101,阵列上的栅极驱动(gate driver on array,GOA)102,有源像素传感器(active pixel sensor,APS)103、模拟前端(analog front end,AFE)104、现场可编程门阵列(field programmable gate array)/微控制器(microcontroller unit)105、应用处理器(application processor)106、显示屏模组107。
其中,TFT面板101为指纹传感器所在的面板,其侧边是GOA 102,用于行选线的依次选通。指纹传感器包括像素传感器阵列,该像素传感器阵列包括对应于每个像素的APS103。AFE 104用于采集TFT面板101所探测的指纹信号,该指纹信号为模拟信号,并输出其对应的数字信号。FPGA/MCU 105用于控制AFE 104的时序以及控制GOA,并对AFE104的指纹数据进行接口转换,将转换后的指纹数据输送给应用处理器106进行特征提取和比对处理。显示屏模组107包含自发光的像素,比如有机发光二极管(organic light-emitting diode,OLED),可以为采集指纹提供照明。
图2示出了本申请实施例提供的一种光信号处理电路的示意图,该光信号处理电路包括:光敏器件201(如光敏二极管(photo diode,PD)、有机光电探测器(organic photodetector,OPD)),放大管T
1,开关管T
2,开关管T
3、读出电路202、控制电路203和电压可调电源204。其中,光敏器件201与T
1的栅极连接,T
1的栅极和漏极之间跨接T
2,T
1的源 极连接电压可调电源204,T
1的源极或漏极通过T
3连接读出电路202,控制电路203与T
2、T
3和所述电压可调电源连接。这里,T
1用于对输入的指纹信号的放大。这里,T
2跨接在T
1的栅极和漏极之间,即指的是T
2的输入端、输出端分别连接T
1的栅极和漏极,T
2的控制端连接控制电路203,在控制电路的控制下T
2闭合或者断开。
具体的,控制电路203例如为图1中的GOA 102,能够产生补偿复位控制信号和读取控制信号。下文将以补偿复位控制信号为第一扫描信号(scan1),以读取控制信号为第二扫描信号(scan1)为例进行描述,但这并不对本申请实施例构成限定。
本申请实施例中,控制电路203输出的控制信号可以控制光信号处理电路处于补偿复位阶段、曝光阶段和读取阶段。具体的,光信号处理电路可以在scan1和scan2的控制下进行上述工作流程,以读取指纹信号。应理解,该工作流程中的三个阶段还可以具有其他命令方式,例如补偿复位阶段、曝光阶段和读取阶段可以依次被称为第一状态、第二状态和第三状态等,本申请实施例对此不作限制。
具体的,所述控制电路用于控制所述光信号处理电路处于补偿复位阶段,其中,当所述光信号处理电路处于所述补偿复位阶段时,所述光敏器件没有曝光,当所述控制电路用于控制所述光信号处理电路处于所述补偿复位阶段时,所述控制电路具体用于控制所述开关管T
2导通,控制所述电压可调电源产生补偿复位电压,以及控制所述开关管T
3断开,以使得所述放大管T
1的栅源电压Vgs等于所述第一TFT的阈值电压V
T。
所述控制电路还用于控制所述光信号处理电路处于曝光阶段,所述曝光阶段是所述补偿复位阶段之后的一个阶段,当所述光信号处理电路处于所述曝光阶段时,所述光敏器件曝光并产生施加到所述放大管T
1的栅极的输入电压;当所述控制电路用于控制所述光信号处理电路处于所述曝光阶段时,所述控制电路具体用于控制所述开关管T
2断开,控制所述电压可调电源与所述放大管T
1的源极断开,且控制所述开关管T
3断开。这里的“断开”,指的是电压可调电源不向放大管T
1提供电压。
所述控制电路还用于控制所述光信号处理电路处于读取阶段,所述读取阶段是所述第曝光阶段之后的一个阶段,当所述光信号处理电路处于所述曝光阶段时,所述光敏器件停止曝光;当所述控制电路用于控制所述光信号处理电路处于所述曝光阶段时,所述控制电路具体用于控制所述开关管T
2断开,控制所述开关管T
3导通,控制所述电压可调电源产生读取参考电压,以使得所述放大管T
1的Vgs为所述V
T、所述输入电压和电压增量之和,其中所述电压增量为所述补偿复位电压与所述读取参考电压的幅值之差,从而使得所述读出电路获取所述放大管T
1的输出信号。
可选的,本申请实施例中,当读出电路是基于积分电路时,获取的输出信号为输出电流。
以控制电路203产生scan1和scan2为例,在处于补偿复位阶段时,scan1控制所述T
2导通,scan2控制T
3断开,scan1和/或scan2控制所述电压可调电源产生补偿复位电压(V
DD)。由于T
1的栅极和漏极短接,栅源电压Vgs会下降。当栅源电压Vgs降到与T
1的阈值电压V
T相等时,T
1处于截止状态,栅源电压Vgs不再下降,因而使得T
1的栅源电压Vgs维持在T
1的阈值电压V
T。也就是说在此阶段,完成了放大管T
1的阈值补偿,使得T
1的栅极电压刚刚达到使放大管T
1开启的电平。
在T
1的栅极电压达到使放大管T
1开启的电平之后,光信号处理电路处于曝光阶段。 在曝光阶段,scan1控制T
2断开,且scan2控制T
3断开,scan1和/或scan2控制T
1的源极与所述可调节电压断开。也就是说,在T
1的栅极电压达到使放大管T
1开启的电平之后,光敏器件201曝光,此时光敏器件获取指纹光信号。然后光敏器件对光信号进行光电转换产生电荷,使得光敏器件201与放大管T
1的栅极相连之处的电压发生变化。也就是说,光敏器件在曝光之后产生输入电压,该输入电压施加到T
1的栅极。
在光敏器件201曝光结束后,所述光信号处理电路进入读取阶段。具体的,scan1控制T
2断开,scan2控制T
3导通,以实现读出电路202对指纹信号(即T
1的输出电流)的读取。并且,scan1和/或scan2控制所述电压可调电源产生读取参考电压。此时所述第一TFT的Vgs为所述V
T、所述输入电压和电压增量之和,其中所述电压增量用于让Vgs更大,从而让输出信号也更大,根据Vgs采用正电平还是负电平,电压增加也可以相应地采用正电平或者负电平,电压增量具体为所述补偿复位电压与所述读取参考电压的幅值之差,通过引入电压增量,所述读出电路能够获取到所述放大管T
1输出的更大的信号。
由于光信号处理电路在补偿复位阶段时,T
1的栅极电压刚刚达到使放大管T
1开启的电平,因此当T
1的栅极再施加该输入电压和电压增量时,T
1的栅源电压Vgs将变大,T
1将对输入电压信号进行放大,产生输出信号。
并且,本申请实施例通过放大晶体管T
1的源极连接可调节电压,在T
1的补偿阶段使得可调节电压为补偿复位电压,在指纹信号的读取阶段使得可调节电压为读取参考电压,使得T
1的栅极在读取指纹信号时,栅源电压Vgs的增加量为指纹信号对应的输入电压和电压增量之和。本申请实施例中,电压增量能够使得T
1的栅源电压Vgs进一步增大,进而提高放大电路的静态工作点,实现对输入指纹信号的进一步放大。因此本申请实施例能够实现对放大晶体管T
1的增益控制,提高指纹传感器输出信号信噪比,提高指纹识别率。
需要说明的是,本申请实施例中,电压增量的取值范围为大于0V,使得信号处理电路在读取阶段时,Vgs大于Vt和由于光敏器件曝光产生的输入电压之和。换句话说,本申请实施例中通过控制补偿复位电压与所述读取参考电压的压差值,实现对T
1的增益控制。
可选的,本申请实施例中,所述电压可调电源可以包括选择电路、第一电源和第二电源,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压。
其中,选择电路可以用于选择所述第一电源与所述放大管T
1的源极连接,第二电源不与所述放大管T
1的源极连接。或者,选择电路可以选择所述第二电源与所述放大管T
1的源极连接,第一电源不与所述放大管T
1的源极连接。或者选择电路可以选择所述第一电源和所述第二电源均不与所述放大管T
1的源极连接。
这里,选择电路还可以称为切换电路,或者其他名称,本申请实施例对此不作限定。
可选的,本申请实施例中,电压可调电源中可以包括电压控制电路和可调节电源,可调节电源可以产生可以调节大小的电压值。其中,电压控制电路可以在控制电路的控制下调节可调节电源产生的电压值,使电压值根据需要为补偿复位电压或读取参考电压,或者根据需要使可调节电源与放大管T
1的源极断开。
一个可选的实施例,T
1为N型TFT,T
1的栅极与光敏器件201的阳极连接。
可选的,所述放大管T
1的漏极通过所述开关管T
3连接所述读出电路;所述电压可调电源包括开关管T
4、开关管T
5、第一电源和第二电源,其中,所述开关管T
4与所述第一 电源连接,所述开关管T
5与所述第二电源连接,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压。
当所述控制电路控制所述开关管T
4导通、所述开关管T
5断开时,所述第一电源与所述放大管T
1的源极连接;当所述控制电路控制所述开关管T
4断开、所述开关管T
5导通时,所述第二电源与所述放大管T
1的源极连接;当所述控制电路控制所述开关管T
4断开、所述开关管T
5断开时,所述第一电源和所述第二电源均不与所述放大管T
1的源极连接。
图3示出了本申请实施例提供的一种可选的光信号处理电路的示意图。在图3中,以光敏器件为PD为例。其中,T
1为N型TFT,PD的阳极连接T
1的栅极,PD的阴极接地(GND),T
1的漏极通过T
3连接读出电路,T
1的源极通过开关管T
4连接到补偿复位电压V
DD,T
1的源极还通过开关管T
5连接到读取参考电压。如图3所示,本申请实施例中,读取参考电压为偏置电压Vbias。应注意,图3仅示例性地示出了各个电压值,并未示出用于产生各个电压的电源,但这并不会对本申请实施例构成限定。
本申请实施例中,当控制T
4导通,T
5断开时,T
1的源极连接可调节电压且可调节电压等于补偿复位电压V
DD;当控制T
4断开,T
5导通时,T
1的源极连接可调节电压且可调节电压等于读取参考电压Vbias。
可选的,本申请实施例中,T
1、T
2、T
3、T
4、T
5均为N型TFT,此时scan1输入至T
2、T
4的栅极,scan2输入至T
3、T
5的栅极。当scan1为高电平,scan2为低电平时,T
2、T
4导通,T
3、T
5断开;当scan1和scan2都为低电平时,T
2、T
3、T
4、T
5都断开;当scan1为低电平,scan2为高电平时,T
2、T
4断开,T
3、T
5导通。
作为示例,本申请实施例中,补偿复位电压V
DD可以设置为-4.5V,读取参考电压Vbias可以设置为-6V。可以理解,本申请实施例中,补偿复位电压V
DD以及读取参考电压Vbias还可以设置为其他电压值,以使得T
1对输入指纹信号(即输入电压)进行放大,本申请实施例对此不作具体限定。
图4示出了本申请实施例光信号处理电路工作时的scan1和scan2的示意图。具体的,当光信号处理电路在上一帧读数据时,scan1为低电平,scan2为高电平,此时T
3、T
5闭合(即导通),T
2、T
4开路(即断开)。然后,光信号处理电路进入补偿复位阶段,scan1变为高电平,scan2变为低电平,此时T
2、T
4闭合(即导通),T
3、T
5开路(即断开),由于T
1的栅极和漏极短接,Vgs下降至等于T
1的阈值电压V
T,此时PD的正极电压维持在VDD+V
T。然后,光信号处理电路进入曝光阶段,scan1和scan2均为低电平,T
2、T
3、T
4、T
5都断开,PD由于感光,其正极电压会上升。当曝光时间结束后,即曝光阶段结束,进入读取阶段,scan1为低电平,scan2为高电平,此时T
3、T
5闭合(即导通),T
2、T
4开路(即断开),此时T
1在偏置的情况下进入放大状态,读出电路可以读取到放大后的信号。并且,由于T
5导通,T
1的源极电压从复位时的V
DD变成了更低的Vbias,这相当于增加了输入信号的幅值(增量为V
DD-Vbias),即此时Vgs=V
T+(V
DD-Vbias),从而可以提高放大后信号的输出幅度,进而能够提高读取电路读取的信号的信噪比,提高指纹识别率。然后,可以进行下一帧数据读取,即scan1为高电平,scan2为低电平,进入下一帧的补偿复位阶段。
需要说明的是,本申请实施例中,T
1进入放大状态,指的是T
1能够对输入的信号进行放大,此时T
1可以处于可变电阻区,或者饱和区,本申请实施例对此不作限定。
另一个可选的实施例,T
1为P型TFT,T
1的栅极与光敏器件201的阴极连接。
可选的,所述放大管T
1的漏极通过开关管T
6连接至偏置电源,光敏器件的阳极连接到所述偏置电源,其中,所述偏置电源用于产生偏置电压;所述电压可调电源包括开关管T
7、所述开关管T
3、第一电源和第二电源,其中,所述开关管T
7与所述第一电源连接,所述放大管T
1的源极通过所述开关管T
3连接所述读出电路,其中,所述读出电路包括运放电路,所述运放电路的同相输入端连接所述第二电源,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压。
当所述控制电路控制所述开关管T
7导通、所述开关管T
3断开时,所述第一电源与所述放大管T
1的源极连接;当所述控制电路控制所述开关管T
7断开、所述开关管T
3导通时,所述第二电源与所述放大管T
1的源极连接;当所述控制电路控制所述开关管T
7断开、所述开关管T
3断开时,所述第一电源和所述第二电源均不与所述放大管T
1的源极连接。
图5示出了本申请实施例提供的一种可选的光信号处理电路的示意图。在图5中,以光敏器件为PD为例。其中,T
1为P型TFTMOS晶体管,PD的阴极连接T
1的栅极,阳极连接偏置电压Vbias,T
1的漏极通过开关管T
6连接至偏置电压Vbias,T
1的源极还通过开关管T
7连接到补偿复位电压V
DD,并且T
1的源极通过T
3连接读出电路,其中,该读出电路包括运放电路,该运放电路的同相输入端连接到读取参考电压,这里读取参考电压例如为Vref。应注意,图5仅示例性地示出了各个电压值,并未示出用于产生各个电压的电源,但这并不会对本申请实施例构成限定。
本申请实施例中,当控制T
7导通,T
3断开时,T
1的源极连接可调节电压且可调节电压等于补偿复位电压V
DD;当控制T
7断开,T
3导通时,T
1的源极连接可调节电压且可调节电压等于读取参考电压Vref。
可选的,本申请实施例中,T
1、T
2、T
3、T
6、T
7均为P型TFT,此时scan1输入至T
2、T
7的栅极,scan2输入至T
3、T
6的栅极。当scan1为高电平,scan2为低电平时,T
2、T
7导通,T
3、T
6断开;当scan1和scan2都为低电平时,T
2、T
3、T
6、T
7都断开;当scan1为低电平,scan2为高电平时,T
2、T
7断开,T
3、T
6导通。
作为示例,本申请实施例中,补偿复位电压V
DD可以设置为-1V,读取参考电压Vref可以设置为-0.6V,偏置电压Vbias可以设置为-6V。应注意,本申请实施例中,补偿复位电压V
DD、读取参考电压Vref和偏置电压Vbias还可以设置为其他电压值,以使得T
1对输入指纹信号(即输入电压)进行放大,本申请实施例对此不作具体限定。
图6示出了本申请实施例光信号处理电路工作时的scan1和scan2的示意图。具体的,当光信号处理电路在上一帧读数据时,scan1为高电平,scan2为低电平,此时T
3、T
6闭合(即导通),T
2、T
7开路(即断开)。然后,光信号处理电路进入补偿复位阶段,scan1变为低电平,scan2变为高电平,此时T
2、T
7闭合(即导通),T
3、T
6开路(即断开),由于T
1的栅极和漏极短接,Vgs上升至等于T
1的阈值电压V
T,此时PD的阴极电压维持在Vbias+V
T。然后,光信号处理电路进入曝光阶段,scan1和scan2均为高电平,T
2、T
3、T
6、T
7都断开,PD由于感光,其阴电压会下降。当曝光时间结束后,即曝光阶段结束,进入读取阶段,scan1为高电平,scan2为低电平,此时T
3、T
6闭合(即导通),T
2、T
7开路(即断开),此时T
1在偏置的情况下进入放大状态,读出电路可以读取到放大后的信号。并且,由于T
3导通,T
1的源极电压从复位时的V
DD变成了更高的Vref,这相当于 增加了输入信号的幅值(增量为Vref-V
DD),即此时Vgs=V
T+(Vbias-V
DD),从而可以提高放大后信号的输出幅度,进而能够提高读取电路读取的信号的信噪比,提高指纹识别率。然后,可以进行下一帧数据读取,即scan1为低电平,scan2为高电平,进入下一帧的补偿复位阶段。
本申请实施例中,N型TFT可以采用NMOS工艺,P型TFT可以采用PMOS工艺。可选的,本申请实施例中,放大管或开关管还可以为其他类型的晶体管,本申请实施例仅以TFT为例进行描述,但这并不会对本申请实施例的技术方案构成限定。
可选的,本申请实施例还提供一种光信号处理电路,可以包括至少两行上述实施例中的光信号处理电路,所述至少两行中的每一行光信号处理电路包括至少一个光信号处理电路,,其中所述至少两行光信号处理电路共用控制电路。其中,所述共用控制电路用于向所述至少两行中的第一行光信号处理电路和所述至少两行中第二行光信号处理电路输入同一控制信号,所述控制信号用于控制第一行光信号处理电路在处于所述补偿复位阶段,且所述第二行像素处理电路处于所述读取阶段。也就是说,同一控制信号能够同时控制一个光信号处理电路处于补偿复位阶段,另一个光信号处理电路处于读取阶段。
一种可能的实现方式,指纹传感器,即像素传感器阵列中可以包括至少两行光信号处理电路,每行光信号处理电路包括至少一个如上文所述的光信号处理电路。其中,控制电路包括至少两个栅线,每个栅线向每一行光信号处理电路输入补偿复位控制信号(比如scan1),并同时向该行光信号处理电路的上一行光信号处理电路输入读取控制信号(比如scan2)。换句话说,一个栅线同时连接两行光信号处理电路,该栅线提供的控制信号,可以作为其中一行光信号处理电路的补偿复位控制信号,同时也可以作为其中另一行光信号处理电路的读取控制信号。
图7示出了本申请实施例提供的一种指纹传感器的部分示意图。该指纹传感器中包括至少两行APS,每行APS至少包括一个APS,作为示例,图7仅示出了三行APS,每行APS包括2个APS,具体的第一行APS包括APS 1、APS 4,第二行APS包括APS 2、APS 5,第三行APS包APS 3、APS 6.对应的,图7中仅示出了栅线(gate line)2和栅线3,以及两个数据线(data line)。其中,栅线2为第一行的APS 1和APS 4提供scan1信号,同时为第二行的APS 2和APS 5提供scan2信号。栅线3为第二行的APS 2和APS 5提供scan1信号,同时为第三行的APS 3和APS 6提供scan2信号。另外,每一列APS的输出端连接同一数据线,作为举例,APS 1、APS 2、APS 3的输出端连接同一数据线,APS 4、APS 5、APS 6的输出端连接同一数据线。
因此,本申请实施例可以实现在读取当前行的指纹信号时,同时对上一行已完成读取的APS进行补偿复位,准备开始下一帧的曝光,从而实现了读取、补偿复位操作在一次扫描的过程中一并完成。
本申请实施例还提供了一种指纹识别***,该指纹识别***包括本申请实施例的任一种可能光信号处理电路。
本申请实施例还提供了一种电子设备,该电子设备包括本申请实施例的任一种可能光信号处理***、面板、显示屏模组和处理器,和/或其他模块/单元,其中,所述光信号处理***设置于所述面板,所述显示屏模组用于为所述光信号处理电路提供照明,所述处理器用于对所述光信号处理电路输出的输出信号进行处理。。
本领域普通技术人员可以意识到,结合本文中所公开的实施例描述的各示例的单元及算法步骤,能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行,取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能,但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到,为描述的方便和简洁,上述描述的***、装置和单元的具体工作过程,可以参考前述方法实施例中的对应过程,在此不再赘述。
在本申请所提供的几个实施例中,应该理解到,所揭露的***、装置和方法,可以通过其它的方式实现。例如,以上所描述的装置实施例仅仅是示意性的,例如,所述单元的划分,仅仅为一种逻辑功能划分,实际实现时可以有另外的划分方式,例如多个单元或组件可以结合或者可以集成到另一个***,或一些特征可以忽略,或不执行。另一点,所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口,装置或单元的间接耦合或通信连接,可以是电性,机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的,作为单元显示的部件可以是或者也可以不是物理单元,即可以位于一个地方,或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外,在本申请各个实施例中的各功能单元可以集成在一个处理单元中,也可以是各个单元单独物理存在,也可以两个或两个以上单元集成在一个单元中。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时,可以存储在一个计算机可读取存储介质中。基于这样的理解,本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来,该计算机软件产品存储在一个存储介质中,包括若干指令用以使得一台计算机设备(可以是个人计算机,服务器,或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括:U盘、移动硬盘、只读存储器(read-only memory,ROM)、随机存取存储器(random access memory,RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述,仅为本申请的具体实施方式,但本申请的保护范围并不局限于此,任何熟悉本技术领域的技术人员在本申请揭露的技术范围内,可轻易想到变化或替换,都应涵盖在本申请的保护范围之内。因此,本申请的保护范围应以所述权利要求的保护范围为准。
Claims (12)
- 一种光信号处理电路,其特征在于,包括:光敏器件,放大管T 1,开关管T 2,开关管T 3,读出电路,控制电路和电压可调电源,其中,所述光敏器件与所述放大管T 1的栅极连接,所述放大管T 1的栅极和漏极之间跨接所述开关管T 2,所述放大管T 1的源极连接所述电压可调电源,所述放大管T 1的源极或漏极通过所述开关管T 3连接所述读出电路,所述控制电路与所述开关管T 2、所述开关管T 3和所述电压可调电源连接;所述控制电路用于控制所述光信号处理电路处于第一状态,其中,当所述光信号处理电路处于所述第一状态时,所述光敏器件没有曝光;当所述控制电路用于控制所述光信号处理电路处于所述第一状态时,所述控制电路具体用于控制所述开关管T 2导通,控制所述电压可调电源产生补偿复位电压,以及控制所述开关管T 3断开,以使得所述放大管T 1的栅源电压Vgs等于所述第一TFT的阈值电压V T;所述控制电路还用于控制所述光信号处理电路处于第二状态,所述第二状态是所述第一状态之后的一个状态,当所述光信号处理电路处于所述第二状态时,所述光敏器件曝光并产生施加到所述放大管T 1的栅极的输入电压;当所述控制电路用于控制所述光信号处理电路处于所述第二状态时,所述控制电路具体用于控制所述开关管T 2断开,控制所述电压可调电源与所述放大管T 1的源极断开,且控制所述开关管T 3断开;所述控制电路还用于控制所述光信号处理电路处于第三状态,所述第三状态是所述第二状态之后的一个状态,当所述光信号处理电路处于所述第三状态时,所述光敏器件停止曝光;当所述控制电路用于控制所述光信号处理电路处于所述第三状态时,所述控制电路具体用于控制所述开关管T 2断开,控制所述开关管T 3导通,从而使得所述读出电路获取所述放大管T 1的输出信号,所述控制电路还具体用于控制所述电压可调电源产生读取参考电压,以使得所述放大管T 1的Vgs为所述V T、所述输入电压和电压增量之和,其中所述电压增量为所述补偿复位电压与所述读取参考电压的幅值之差。
- 根据权利要求1所述的电路,其特征在于,所述放大管T 1为N型薄膜晶体管TFT,所述放大管T 1的栅极与所述光敏器件的阳极连接。
- 根据权利要求2所述的电路,其特征在于,所述放大管T 1的漏极通过所述开关管T 3连接所述读出电路;所述电压可调电源包括开关管T 4、开关管T 5、第一电源和第二电源,其中,所述开关管T 4与所述第一电源连接,所述开关管T 5与所述第二电源连接,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压;当所述控制电路控制所述开关管T 4导通、所述开关管T 5断开时,所述第一电源与所述放大管T 1的源极连接;当所述控制电路控制所述开关管T 4断开、所述开关管T 5导通时,所述第二电源与所述放大管T 1的源极连接;当所述控制电路控制所述开关管T 4断开、所述开关管T 5断开时,所述第一电源和所述第二电源均不与所述放大管T 1的源极连接。
- 根据权利要求3所述的电路,其特征在于,所述开关管T 2、所述开关管T 3、所述开关管T 4和所述开关管T 5均为N型TFT。
- 根据权利要求2-4任一项所述的电路,其特征在于,所述补偿复位电压为-4.5V,所述读取参考电压为-6V。
- 根据权利要求1所述的电路,其特征在于,所述放大管T 1为P型TFT,所述放大管T 1的栅极与所述光敏器件的阴极连接。
- 根据权利要求6所述的电路,其特征在于,所述放大管T 1的漏极通过开关管T 6连接至偏置电源,光敏器件的阳极连接到所述偏置电源,其中,所述偏置电源用于产生偏置电压;所述电压可调电源包括开关管T 7、所述开关管T 3、第一电源和第二电源,其中,所述开关管T 7与所述第一电源连接,所述放大管T 1的源极通过所述开关管T 3连接所述读出电路,其中,所述读出电路包括运放电路,所述运放电路的同相输入端连接所述第二电源,所述第一电源用于产生所述补偿复位电压,所述第二电源用于产生所述读取参考电压;当所述控制电路控制所述开关管T 7导通、所述开关管T 3断开时,所述第一电源与所述放大管T 1的源极连接;当所述控制电路控制所述开关管T 7断开、所述开关管T 3导通时,所述第二电源与所述放大管T 1的源极连接;当所述控制电路控制所述开关管T 7断开、所述开关管T 3断开时,所述第一电源和所述第二电源均不与所述放大管T 1的源极连接。
- 根据权利要求7所述的电路,其特征在于,所述开关管T 2、所述开关管T 3、所述开关管T 6和所述开关管T 7均为P型TFT。
- 根据权利要求6-8任一项所述的电路,其特征在于,所述补偿复位电压为-1V,所述读取参考电压为-0.6V。
- 如权利要求1-9任一项所述的电路,其特征在于,所述光敏器件为光敏二极管,或者有机光电探测器。
- 一种光信号处理***,其特征在于,包括至少两行如权利要求1-9任一项所述的光信号处理电路,所述至少两行中的每一行包括至少一个所述光信号处理电路,其中所述至少两行光信号处理电路共用控制电路;其中,所述共用控制电路用于向所述至少两行中的第一行光信号处理电路和所述至少两行中第二行光信号处理电路输入同一控制信号,所述控制信号用于控制第一行光信号处理电路在处于所述第一状态,且所述第二行光信号处理电路处于所述第三状态。
- 一种电子设备,其特征在于,包括如权利要求11所述的光信号处理***、面板、显示屏模组和处理器,其中,所述光信号处理***设置于所述面板,所述显示屏模组用于为所述光信号处理电路提供照明,所述处理器用于对所述光信号处理电路输出的输出信号进行处理。
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