Control method and control circuit of optical fingerprint sensor

Abstract

The present invention discloses a control method and a control circuit for an optical fingerprint sensor and a touch controller. The optical fingerprint sensor includes a plurality of pixels, each of which has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line and a sensing line. The control method includes the following steps: when the touch controller is in a touch operation period, at least one of the first control signal line, the second control signal line, the first voltage source line, the second voltage source line and the sensing line applies an anti-load driving signal.

Description

Technical Field

[0001] The present invention relates to a control method for an optical fingerprint sensor, and more particularly to a control method for an optical fingerprint sensor that can be integrated with a touch screen. Background Art

[0002] Fingerprint recognition technology has been widely used in a variety of electronic products, such as mobile phones, laptops, tablet computers, personal digital assistants (PDAs), and portable electronic devices, to achieve identity recognition. Fingerprint sensing can easily identify users. Users only need to place their fingers on the fingerprint sensing panel or area to log in to the electronic device without having to enter a long and cumbersome user name and password.

[0003] Among various types of fingerprint sensing technologies, optical fingerprint sensing solutions are usually applied to electronic products with display screens. Generally speaking, optical fingerprint sensing can be integrated with touch screens so that fingerprint sensing and touch sensing operations can be implemented simultaneously in electronic devices. However, in order to capture the tiny peak-to-trough difference of fingerprints, optical fingerprint sensing operations need to be performed accurately, and optical fingerprint sensing is easily interfered by touch sensing operations. In view of this, there is a need for improvement in the existing technology. Summary of the invention

[0004] Therefore, the main purpose of the present invention is to provide a control method and a control circuit thereof and an optical fingerprint sensor that can be used for an optical fingerprint sensor, so as to eliminate or reduce the interference between the touch sensing operation and the fingerprint sensing operation.

[0005] An embodiment of the present invention discloses a control method for an optical fingerprint sensor and a touch controller. The optical fingerprint sensor includes a plurality of pixels, each of which has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line and a sensing line. The control method includes: when the touch controller is in a touch operation period, at least one of the first control signal line, the second control signal line, the first voltage source line, the second voltage source line, and the sensing line applies an anti-loading driving (ALD) signal.

[0006] Another embodiment of the present invention discloses a control method for an optical fingerprint sensor and a touch controller. The optical fingerprint sensor includes a plurality of pixels, each of which has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line and a sensing line. The control method includes: when the touch controller is in a touch operation period, the first control signal line, the second control signal line, the first voltage source line, the second voltage source line, and the sensing line are all in a floating state.

[0007] Another embodiment of the present invention discloses a control circuit for controlling an optical fingerprint sensor. The optical fingerprint sensor includes a plurality of pixels, each of which has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line, and a sensing line. The control circuit is integrated with a touch controller to perform the following operations: when the touch controller is in a touch operation period, at least one of the first control signal line, the second control signal line, the first voltage source line, the second voltage source line, and the sensing line applies an anti-load driving signal.

[0008] Another embodiment of the present invention discloses a control circuit for controlling an optical fingerprint sensor. The optical fingerprint sensor includes a plurality of pixels, each of which has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line, and a sensing line. The control circuit is integrated with a touch controller to perform the following operations: when the touch controller is in a touch operation period, the first control signal line, the second control signal line, the first voltage source line, the second voltage source line, and the sensing line are all in a floating state. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG. 1 is a schematic diagram of a display device according to an embodiment of the present invention.

[0010] Figure 2 Shows Figure 1 3D view of the display device in.

[0011] Figure 3 Shows Figure 1 and Figure 2 Detailed structure of a fingerprint sensing pixel included in the fingerprint sensing layer.

[0012] Figure 4 Schematic diagram of the arrangement of control signal lines, sensing lines and voltage supply lines in a fingerprint sensing pixel array.

[0013] Figure 5A Schematic diagram of applying an anti-load driving signal to a fingerprint sensing pixel.

[0014] Figure 5B A detailed implementation of applying an anti-load driving signal to control node floating is shown.

[0015] Figure 6 A timing diagram showing the operation of a device according to an embodiment of the present invention.

[0016] Figure 7 A detailed implementation of an anti-load driving signal during a touch operation is shown.

[0017] Figure 8 FIG. 1 is a schematic diagram of a display system according to an embodiment of the present invention.

[0018] Fig. 9 FIG. 4 is a schematic diagram of another display system according to an embodiment of the present invention.

[0019] Fig.10 Schematic diagram of an anti-load driving circuit according to an embodiment of the present invention.

[0020] Fig.11A and 11B FIG. 1 is a schematic diagram of a detailed implementation of an anti-load drive generator.

[0021] Fig.12 FIG. 4 is a schematic diagram of another display system according to an embodiment of the present invention.

[0022] Fig.13 The figure is a flow chart of a process of an embodiment of the present invention.

[0023] Fig.14 A flowchart of another process of an embodiment of the present invention

[0024] The reference numerals are described as follows:

[0025] 10 Display Devices

[0026] 100, 804 display screen

[0027] 102 row drive

[0028] 104 columns sensing drive device

[0029] 110 touch sensing layer

[0030] 120 Fingerprint sensing layer

[0031] 112_1, 112_2 switch circuit

[0032] PD Photoelectric Components

[0033] SC Storage Capacitor

[0034] T1~T3 transistors

[0035] SVSS First voltage source line

[0036] SVDD Second voltage supply line

[0037] R_SW1~R_SW3 control signal line

[0038] C_SEN sensing line

[0039] N1 and N2 nodes

[0040] CC1, CC2, CC coupling capacitors

[0041] PSW1~PSW5 Switch

[0042] 80, 90, 1200 display system

[0043] 800 System Processor

[0044] 802 Fingerprint Touch Display Integrated Circuit

[0045] 820 Fingerprint Control Circuit

[0046] 822 Touch Control Device

[0047] 824 Display driver

[0048] 850, 950, 1000, 1250 load-resistant drive circuit

[0049] 902 Touch Display Driver Integrated Circuit

[0050] 903 Fingerprint Reading Circuit

[0051] 1002 Voltage Generator

[0052] 1004 Anti-load drive generator

[0053] ALDX Raw Anti-Load Drive Signal

[0054] VH, V1, V2 voltage

[0055] 1102, 1104 Voltage Regulator

[0056] 1110 Switch Module

[0057] C1, C2 capacitors

[0058] 1150 Digital to Analog Converter

[0059] DIG Digital Code

[0060] CTRL control signal

[0061] 1300, 1400 Process

[0062] Steps 1302-1306, 1402-1406 DETAILED DESCRIPTION

[0063] Please refer to Figure 1 , Figure 1 FIG. 1 is a schematic diagram of a display device 10 according to an embodiment of the present invention. Figure 1 As shown, the display device 10 includes a display screen 100, a row driving device 102 and a column sensing driving device 104. In this example, the display screen 100 can be set to have touch sensing and fingerprint sensing functions, so a touch sensing layer 110 with a touch sensor array and a fingerprint sensing layer 120 with a fingerprint sensing pixel array can be overlapped and integrated in the display screen 100. The row driving device 102 and the column sensing driving device 104 can constitute a control circuit for the fingerprint sensing pixel array. The display device 10 may also include switch circuits 112_1 and 112_2, wherein each switch circuit may be composed of a multiplexer and / or a switch, which is used to select the target fingerprint sensing pixel in the fingerprint sensing layer 120 to transmit the control signal, or to transmit the sensing signal from the fingerprint sensing pixel to the target receiver circuit in the column sensing driving device 104. The display device 10 may also include control circuits for display and touch sensing. For simplicity, these control circuits are omitted. Figure 1 .

[0064] Figure 2 3D view of the display device 10 is shown. In detail, the touch sensing layer 110 includes a touch sensor array, wherein the touch sensor array has a plurality of sensing pads and a plurality of wires. The touch controller can transmit a touch driving signal to the sensing pad, and correspondingly receive a touch sensing signal to determine the touch behavior. The touch driving signal can be a periodic signal, which can have any type of pulse, such as a sine wave, a square wave, a triangle wave or a trapezoidal wave. Therefore, the touch sensing signal can also be a corresponding periodic signal for carrying touch sensing information. The fingerprint sensing layer 120 includes a fingerprint sensing pixel array, wherein each fingerprint sensing pixel can include a plurality of circuit components, which are respectively connected to each other by wires in the row direction and the column direction, wherein the wires in the row direction are connected to the row driving device 102 and the wires in the column direction are connected to the column sensing driving device 104. These wires can include a plurality of control signal wires for transmitting control signals, a plurality of voltage supply wires for transmitting power supply voltages, and a plurality of sensing wires for transmitting fingerprint sensing signals.

[0065] like Figure 2As shown, the touch sensing layer 110 and the fingerprint sensing layer 120 are different layers but close to each other, resulting in a non-negligible coupling capacitance between each wire connecting the touch sensing pad and each wire connecting the fingerprint sensing pixel. Therefore, when a touch driving signal is transmitted to the touch sensing pad, the coupling capacitance can couple the touch driving signal or the corresponding sensing signal to interfere with the voltage on the control signal line, the voltage source line and / or the sensing line, thereby generating a non-negligible capacitive load on the fingerprint sensing operation. From the perspective of the touch sensing operation, the coupling capacitance between the touch sensing layer 110 and the fingerprint sensing layer 120 will also affect the sensing signal of the touch operation.

[0066] In this example, the touch sensing layer 110 is an upper layer stacked on the fingerprint sensing layer 120. However, in another embodiment, the fingerprint sensing layer may be set as an upper layer and the touch sensing layer may be set as a lower layer. Alternatively, the touch sensor and / or the fingerprint sensor may be set as a multi-layer structure. The structure of the panel should not be used to limit the scope of the present invention.

[0067] Figure 3 Shows Figure 1 and Figure 2 Detailed structure of a fingerprint sensing pixel included in the fingerprint sensing layer 120 in FIG. In this example, the fingerprint sensing pixel can be used to implement an optical fingerprint sensor, which includes a photoelectric component PD, a storage capacitor SC and three transistors T1~T3. The fingerprint sensing pixel can be operated by a first power supply voltage received through a first voltage source line SVSS and a second power supply voltage received through a second voltage source line SVDD. In one embodiment, the first power supply voltage can be a negative power supply voltage or a ground voltage or a positive power supply voltage, and the second power supply voltage can be a negative power supply voltage or a ground voltage or a positive power supply voltage. The actual polarity arrangement of the voltage source line is determined by the circuit design of the sensing pixel, and the present invention is not limited thereto. Three rows of control signals can be transmitted to the pixel respectively through the control signal lines R_SW1~R_SW3, so that the pixel can output a sensing signal through a sensing line C_SEN. In another embodiment, the fingerprint sensing pixel can be used to implement an optical fingerprint sensor, which includes a photoelectric component PD, a storage capacitor SC and two transistors T1~T2, so that its circuit structure is more streamlined.

[0068] In the fingerprint sensing pixel, the photoelectric component PD can be a photodiode, which is used to sense light and convert the sensed light intensity into an electronic signal (such as a voltage signal or a current signal). This operation is called "exposure". During the exposure period, the electronic signal will flow to the storage capacitor SC and be stored in the storage capacitor SC. Transistor T1 acts as a reset transistor and can be used to reset the voltage of node N2 (i.e., reset the charge stored in the storage capacitor SC) before the exposure operation. Transistor T2 acts as a source follower, which can transmit the electronic signal sensed by the photoelectric component PD and stored in the storage capacitor SC to the sensing line C_SEN after the exposure operation is completed. Transistor T3 acts as a selection transistor and can be turned on by the corresponding control signal when its corresponding pixel is selected.

[0069] like Figure 3 As shown, the transistor T1 has a gate terminal, a first terminal and a second terminal, wherein the gate terminal is coupled to the control signal line R_SW1 to receive a control signal (such as a reset signal), the first terminal is coupled to the first voltage source line SVSS, and the second terminal is coupled to the photoelectric device PD and the storage capacitor SC. It should be noted that the first terminal of the transistor T1 can be one of the drain terminal and the source terminal, and the second terminal of the transistor T1 is the other, which can be determined according to the current direction of the transistor T1. The photoelectric device PD and the storage capacitor SC both have a first terminal and a second terminal, wherein the first terminal is coupled to the control signal line R_SW2 to receive a control signal (such as a bias voltage), and the second terminal is coupled to the second terminal of the transistor T1. The transistor T2 has a gate terminal, a first terminal and a second terminal, wherein the gate terminal is coupled to the second terminal of the transistor T1, the second terminal of the photoelectric device PD, and the second terminal of the storage capacitor SC, the first terminal is coupled to the second voltage source line SVDD, and the second terminal is coupled to the transistor T3. It should be noted that the first end of the transistor T2 can be one of the drain end and the source end, and the second end of the transistor T2 is the other end, which can be determined according to the current direction of the transistor T2. The transistor T3 has a gate end, a first end and a second end, wherein the gate end is coupled to the control signal line R_SW3 to receive a control signal (such as a selection signal), the first end is coupled to the second end of the transistor T2, and the second end is coupled to the sensing line C_SEN. It should be noted that the first end of the transistor T3 can be one of the drain end and the source end, and the second end of the transistor T3 is the other end, which can be determined according to the current direction of the transistor T3.

[0070] Please refer to Figure 4 , Figure 4 FIG. 1 is a schematic diagram showing the arrangement of control signal lines R_SW1 to R_SW3, sensing lines C_SEN, and voltage source lines SVSS and SVDD in a fingerprint sensing pixel array. Figure 4 Matching Figure 1 As shown, each control signal line R_SW1~R_SW3 is coupled to a row of pixels, each sensing line C_SEN is coupled to a column of pixels, and each voltage source line SVSS or SVDD can be coupled to the pixel through the connection line in the column direction. Therefore, the control signal lines R_SW1~R_SW3 can be coupled to the row driver 102, which is used to send the corresponding control signal. The sensing line C_SEN can be coupled to the column sensing driver 104, which is used to receive the fingerprint sensing signal. Since the control signal lines R_SW1~R_SW3, the sensing line C_SEN and the voltage source lines SVSS and SVDD are all scattered in the fingerprint sensing layer 120, the above wires are all interfered by the touch drive / sensing signal applied to the touch sensing layer 110.

[0071] According to the optical fingerprint sensing operation, the electronic signal generated by the photoelectric component PD is stored in the storage capacitor SC. Therefore, the capacitive load on both ends of the storage capacitor SC (i.e., nodes N1 and N2) should be avoided or reduced. This capacitive load may come from the touch drive or sensing signal on the touch sensing pad. For example, if there is a coupling capacitor between the node N1 in the fingerprint sensing pixel and the touch sensing pad in the touch sensing layer 110, the touch drive or sensing signal applied to the touch sensing pad will cause interference and change the electronic signal stored in the storage capacitor SC, resulting in errors in the output fingerprint sensing signal. In order to eliminate or reduce the capacitive load, when the touch drive signal is transmitted to the touch sensing layer 110, an anti-loading driving (ALD) signal can be applied to the wire of the fingerprint sensing layer 120 or it can be placed in a floating state. When the touch controller is in a touch operation period, at least one of each of the control signal lines R_SW1~R_SW3, the voltage source lines SVSS and SVDD, and the sensing line C_SEN can be applied with an anti-load driving signal, and the others that are not applied with the anti-load driving signal can be placed in a floating state. In another embodiment, when the touch controller is in a touch operation period, each of the control signal lines R_SW1~R_SW3, the voltage source lines SVSS and SVDD, and the sensing line C_SEN can also be placed in a floating state. Disconnecting the switch at the signal source can make the wire float, or make its output high impedance, but the present invention is not limited thereto. In short, by applying an anti-load driving signal or making the wire float, or by using various permutations and combinations of the two technical means, the coupling interference of the signal between the touch controller and the fingerprint sensor can be minimized.

[0072] Please refer to Figure 5A , Figure 5ASchematic diagram of applying an anti-load drive signal to a fingerprint sensing pixel. In detail, a first anti-load drive signal can be applied to the control signal line R_SW2. Since the control signal line R_SW2 is directly coupled to the node N1, the first anti-load drive signal can be transmitted to the node N1 to eliminate or reduce the capacitive load at the first end of the storage capacitor SC. In order to eliminate or reduce the capacitive load at the second end of the storage capacitor SC, a second anti-load drive signal can be transmitted to the node N2. Since the node N2 is coupled to the transistors T1 and T2, the second anti-load drive signal can be applied to any one or more wires connected to the transistors T1 and / or T2. These wires include the control signal line R_SW1, the first voltage supply line SVSS, the second voltage supply line SVDD and the sensing line C_SEN, etc., but are not limited thereto. If the second anti-load drive signal is applied to the control signal line R_SW1 and / or the first voltage supply line SVSS, the second anti-load drive signal can be coupled to the node N2 through the parasitic capacitance of the transistor T1. If the second anti-load driving signal is applied to the second voltage supply line SVDD and / or the sensing line C_SEN, the second anti-load driving signal may be coupled to the node N2 through the parasitic capacitance of the transistor T2 .

[0073] It is worth noting that the purpose of the anti-load driving signal is to eliminate or reduce the capacitive load in the fingerprint sensing pixel. Preferably, the anti-load driving signal can be designed to be completely identical to the touch driving signal transmitted to the touch sensing pad, such as Figure 5A As shown. Through the coupling operation of coupling capacitors CC1 and CC2, the fingerprint sensing pixel will be disturbed by the touch drive signal. In the absence of an anti-load drive signal, when the touch drive signal switches up and down, the voltage change on the touch drive signal will charge and discharge the coupling capacitors CC1 and CC2, resulting in unexpected voltage changes on nodes N1 and / or N2. When the touch drive signal switches up and down, if the anti-load drive signal applied to nodes N1 and N2 is exactly the same as the touch drive signal, the cross-voltage of the coupling capacitors CC1 and CC2 will remain constant, which means that the coupling capacitors CC1 and CC2 are not charged or discharged, and thus do not affect the electronic signal stored in the storage capacitor SC.

[0074] As described above, the touch driving signal may be a periodic signal having a plurality of pulses. Therefore, the anti-load driving signal may also be a modulated signal having a plurality of pulses, the frequency, phase and amplitude of which pulses are substantially the same as the frequency, phase and amplitude of the pulses of the touch driving signal. Since the touch driving signal may include any type of pulses, such as a sine wave, a square wave, a triangle wave or a trapezoidal wave, the anti-load driving signal may be modulated to include pulses of the same or similar type.

[0075] It is worth noting that the anti-load drive signal may be identical to or not identical to the touch signal (e.g., the touch drive signal or the touch sensing signal). For example, in one embodiment, the amplitude of the anti-load drive signal may be slightly smaller than the amplitude of the touch drive signal, and its frequency and phase are substantially the same. Alternatively or additionally, the phase of the anti-load drive signal may be slightly offset relative to the phase of the touch drive signal, and its frequency is substantially the same. If the similarity between the anti-load drive signal and the touch signal is high, the efficiency of controlling the reduction of the capacitive load of the fingerprint sensing pixel can be improved.

[0076] The anti-load driving signal may be applied to the conductor of the fingerprint sensing pixel in any manner. In one embodiment, a target conductor is driven by an anti-load driving signal, and the anti-load driving signal may be applied to the target conductor, wherein the anti-load driving signal is substantially the same as the touch signal (having the same frequency, phase and / or amplitude). Alternatively or additionally, the anti-load driving signal may be applied to a switch of a target conductor to control the corresponding node to be in a floating state, in which case the anti-load driving signal may have any possible form. For example, the anti-load driving signal may be a periodic signal having any type of pulses described above, or may be a signal at an appropriate voltage level that is capable of closing the corresponding switch. As long as the switch can be closed by the anti-load driving signal so that the target node is in a floating state for a period of time, it is a feasible anti-load driving operation. The floating state allows the voltage of the target node to shift up or down with the pulse of the touch signal under the operation of the coupling capacitor CC1 or CC2. The floating state of a node means that each end of the node is only connected to a high impedance endpoint, or any external connection of the node is disconnected, that is, all switches connected to the node are turned off. In order to save power, or when the target wire cannot be driven by a signal, a floating operation can be used. The target wire receiving the anti-load drive signal can be a control signal line R_SW2 coupled to the node N1 and / or any other wire coupled to the pixel, such as control signal lines R_SW1 and R_SW3, a first voltage supply line SVSS, a second voltage supply line SVDD, and a sensing line C_SEN.

[0077] Figure 5B A detailed implementation of applying an anti-load driving signal to control node floating is shown. Figure 5B The pixel structure shown is similar to Figure 5A The pixel structure shown in the figure is shown in the figure, so the signals or components with similar functions are represented by the same symbols. Figure 5BThe structure also includes switches PSW1~PSW5, which are respectively coupled to the control signal line R_SW2, the control signal line R_SW1, the first voltage source line SVSS, the second voltage source line SVDD and the sensing line C_SEN. It should be noted that each switch PSW1~PSW5 can be a switch dedicated to the target pixel, or a switch used to connect a target wire of a row or a column of pixels. In another embodiment, the switch at the signal source can be disconnected to make the signal line, voltage source line or sensing line float, or make its output high impedance, or all the above wires can be connected together and controlled by a main switch, but the present invention is not limited thereto.

[0078] In detail, in order to apply an anti-load driving signal to the fingerprint sensing pixel, a first anti-load driving signal may be applied to the switch PSW1. In this case, the switch PSW1 coupled between the node N1 and the control signal line R_SW2 may be closed, thereby controlling the node N1 to float. In addition, in order to control the node N2 to float, a second anti-load driving signal may be applied to any one or more of the switch PSW2 coupled to the control signal line R_SW1, the switch PSW3 coupled to the first voltage supply line SVSS, the switch PSW4 coupled to the second voltage supply line SVDD, and the switch PSW5 coupled to the sensing line C_SEN. In this case, any node on the pixel coupled to the control signal line R_SW1, the first voltage supply line SVSS, the second voltage supply line SVDD, and the sensing line C_SEN may be in a floating state, so the node N2 is also in a floating state.

[0079] For the fingerprint sensing pixel array on the fingerprint sensing layer 120, the anti-load driving signal on each pixel can be flexibly implemented by driving and / or controlling the node to float with the anti-load driving signal. For example, the wire of a first pixel can be driven by an anti-load driving signal, and the wire of a second pixel can be controlled by an anti-load driving signal to make the corresponding node float. The anti-load driving signal for the fingerprint sensing pixel array with 2 columns (column 1 and column 2) and 2 rows (row 1 and row 2) can be implemented by various methods of Table 1, as shown below:

[0080]

[0081]

[0082] Table 1

[0083] According to Table 1, the anti-load driving signal for the pixel array includes at least 16 different implementations, and the anti-load driving signal can be applied when the touch driving signal is transmitted to the touch component. It should be noted that a general fingerprint sensing pixel array may include more than 2 rows and 2 columns of pixels, so there are more possible combinations of driving and floating operations. In one embodiment, the anti-load driving signal can also be implemented in different ways for different connecting wires for the same row of pixels and / or different connecting wires for the same column of pixels, so as to achieve flexibility in the anti-load driving operation.

[0084] Please refer to Figure 6 , Figure 6 FIG. 1 is a timing diagram of the operation of a display device according to an embodiment of the present invention. In order to reduce the interference between the display, touch sensing, and fingerprint sensing operations, these operations can be performed in different time periods. Figure 6 As shown, in the display time of each frame, the touch operation period (TP) and the display period (DP) are alternately arranged, and the fingerprint sensing period (FP) can be arranged in the blank time between two consecutive display frames. Figure 6 Matching Figure 3 As shown, the operation of the optical fingerprint sensor requires that the node N2 is reset to a predetermined voltage level, then exposure is started, and then the electronic signal generated in the exposure process is read out at the end of the exposure period. Generally speaking, the exposure period can last for a frame of display cycle, which includes multiple display periods and touch operation periods, such as Figure 6 In another embodiment, in order to generate a sufficient amount of sensing signals, the exposure period may also span across several display frames.

[0085] During the exposure period, the photoelectric device PD can continuously generate electronic signals and accumulate them in the storage capacitor SC, causing the voltage of the node N2 to change accordingly. Therefore, an anti-load driving signal needs to be applied during the exposure period to prevent the charge stored in the storage capacitor SC (i.e., the cross voltage of the storage capacitor SC) from being disturbed by the touch signal before the fingerprint sensing signal is read out.

[0086] More specifically, the touch operation can be performed during the touch operation period, that is, the touch driving signal is usually switched up and down during the touch operation period. Therefore, the anti-load driving signal can also be applied during the touch operation period. Figure 7 FIG. 4 shows a detailed implementation of an anti-load driving signal during a touch operation. Figure 7 As shown, during the touch operation period, the touch sensing line can receive a touch signal from a sensing pad, and the touch signal has a square wave pulse, and its amplitude is equal to ΔV. Therefore, the anti-load driving operation can be applied to the fingerprint sensing pixel during the touch operation period.

[0087] In this example, the first voltage supply line SVSS and the second voltage supply line SVDD may transmit a power supply voltage during the fingerprint sensing period and the display period, and transmit an anti-load driving signal during the touch operation period, wherein the anti-load driving signal may include a plurality of pulses, which may be generated by modulating the power supply voltage, and have substantially the same frequency, phase, and amplitude as the touch signal applied to the touch sensing line. The control signal lines R_SW1 to R_SW3 may transmit corresponding control signals during the fingerprint sensing period and the display period, and transmit an anti-load driving signal during the touch operation period, wherein the anti-load driving signal may include a plurality of pulses, which may be generated by modulating the control signal, and have substantially the same frequency, phase, and amplitude as the touch signal applied to the touch sensing line. The sensing line C_SEN may transmit a sensing signal during the fingerprint sensing period, and transmit an anti-load driving signal during the touch operation period, wherein the anti-load driving signal may include a plurality of pulses, which may be generated by modulating the sensing signal, and have substantially the same frequency, phase, and amplitude as the touch signal applied to the touch sensing line.

[0088] Please refer to Figure 8 , Figure 8 FIG. 8 is a schematic diagram of a display system 80 according to an embodiment of the present invention. Figure 8 As shown, the display system 80 includes a system processor 800, a fingerprint, touch and display integration (Fingerprint, Touch and Display Integration, FTDI) circuit 802 and a display screen 804, wherein the fingerprint, touch and display integration circuit 802 can be a single chip integrating display, touch and fingerprint processing circuits. In detail, the system processor 800 can be the core processor of the display system 80, such as a central processing unit (CPU), a microcontroller unit (MCU), or a microprocessor and the like. For a smart phone, the system processor 800 can be a single chip used to control various applications and operations of the mobile phone. It should be noted that the algorithm used for fingerprint recognition is usually quite complex, so fingerprint matching and judgment should be executed on the system processor 800 with huge computing resources, which is more difficult to implement in the fingerprint, touch and display integration circuit 802. The fingerprint, touch and display integration circuit 802 is responsible for capturing or taking out the fingerprint image from the display screen 804, and processing the received fingerprint sensing signal to amplify and obtain the required peak and valley information.

[0089] Display screen 804 may be Figure 1The display screen 100 shown includes a touch sensing layer 110 and a fingerprint sensing layer 120, which are used to realize the three-in-one operation of display, touch sensing and fingerprint sensing. The fingerprint touch display integrated circuit 802 can be used as a control circuit to control the display, touch and fingerprint sensing operations of the display screen 804. In one embodiment, the display screen 804 can be an in-cell touch and fingerprint panel, which is provided with a touch sensor and a fingerprint sensor and related connection circuits. Therefore, the distance between the touch sensing layer 110 and the fingerprint sensing layer 120 is very close, so the coupling capacitor between the touch sensing layer 110 and the fingerprint sensing layer 120 can generate a large amount of load on the fingerprint sensing operation.

[0090] like Figure 8 As shown, the fingerprint touch display integrated circuit 802 integrates a fingerprint control circuit 820, a touch control device 822 and a display driver 824, wherein each module can communicate with the system processor 800 through a specific interface. The fingerprint touch display integrated circuit 802 may also include an anti-load driver circuit 850, which may be optionally set in the touch control device 822 or the fingerprint control circuit 820 (in Figure 8 In the embodiment of the present invention, the anti-load driving circuit 850 is provided in the fingerprint control circuit 820). The fingerprint control circuit 820 may include, for example Figure 1 The row driver (and / or sensing device) and column driver (and / or sensing device) shown can send control signals to control the fingerprint sensing pixels on the display screen 804 so that the pixels output fingerprint sensing signals in a specific order. The fingerprint control circuit 820 can also include a readout circuit for receiving sensing signals from each fingerprint sensing pixel. The touch control device 822 can be used to send touch drive signals to the touch sensing pads on the touch sensing layer in the display screen 804, and receive touch sensing signals accordingly. The display driver 824 can be used to perform display control of the display screen 804. More specifically, the display driver 824 can receive image data from the system processor 800, and generate and output image signals to the display screen 804 accordingly.

[0091] In order to achieve anti-load driving operation, during the touch operation and / or exposure period, the anti-load driving circuit 850 in the fingerprint touch display integrated circuit 802 can also drive the wire connected to the fingerprint sensing pixel through the anti-load driving signal, or control the corresponding node in the fingerprint sensing pixel to float. In one embodiment, the anti-load driving circuit 850 set in the fingerprint control circuit 820 can apply the anti-load driving signal according to the notification received from the touch control device 822, so that the anti-load driving signal is synchronized with the touch signal, and the anti-load driving signal and the touch signal can be set to have the same frequency and phase, and / or the same amplitude. The notification from the touch control device 822 can be in any form, such as a flag, a voltage level, or a signal switch generated on a connection line between the fingerprint control circuit 820 and the touch control device 822.

[0092] During the touch operation, in addition to the fingerprint control circuit 820, the display driver 824 can also apply an anti-load driving signal to the display circuit of the display screen 804, which can avoid or reduce the capacitive load on the display circuit caused by the coupling capacitance between the display pixel and the touch sensing layer.

[0093] It is worth noting that Figure 8 The implementation of the fingerprint touch display integrated circuit 802 is only one of many embodiments of the present invention. In another embodiment, the circuit for controlling the display screen can also be implemented using a dual-chip solution. Please refer to Fig. 9 , Fig. 9 FIG. 8 is a schematic diagram of another display system 90 according to an embodiment of the present invention. The circuit structure of the display system 90 is similar to that of the display system 80, so signals or components with similar functions are represented by the same symbols. Fig. 9As shown, the display system 90 is different from the display system 80 in that the display system 90 includes a touch and display driving integration (TDDI) circuit 902 and a fingerprint readout circuit (FPR ROIC) 903, which can be used to replace the function of the fingerprint touch display integrated circuit 802 in the display system 80. The fingerprint readout circuit 903 can have an anti-load driving circuit 950. The fingerprint readout circuit 903 can be used to read the fingerprint sensing signal from the fingerprint sensing pixel, and can apply the anti-load driving signal to the wire of the fingerprint sensing pixel through the anti-load driving circuit 950. The touch display driving integrated circuit 902 and the fingerprint readout circuit 903 can both be integrated circuits implemented in a chip, and the two chips can work together to control the display, touch sensing and fingerprint sensing operations of the display screen 804. An interface is provided between the touch display driver integration circuit 902 and the fingerprint sensing circuit 903 to transmit necessary information, such as notification of applying an anti-load driving signal and information for synchronizing display driving, touch sensing and fingerprint sensing operations. The detailed operation of the display system 90 is similar to the operation of the display system 80 described above, and is omitted for simplicity.

[0094] The anti-load driving circuit in the fingerprint touch display integrated circuit 802 or the fingerprint reading circuit 903 can be implemented in various ways. Fig.10 , Fig.10 FIG. 1 is a schematic diagram of a load-resistant driving circuit 1000 according to an embodiment of the present invention. Fig.10 As shown, the anti-load driving circuit 1000 includes a voltage generator 1002, an anti-load driving generator 1004 and a coupling capacitor CC. The voltage generator 1002 is used to generate a voltage VH, and the voltage VH can be any possible voltage, such as a control voltage provided to a control signal line or a power supply voltage provided to a voltage source line. The anti-load driving generator 1004 can be used to generate an original anti-load driving signal ALDX. The original anti-load driving signal ALDX can be a periodic signal, which can have any type of pulse, such as a sine wave, a square wave, a triangle wave or a trapezoidal wave. Through the coupling capacitor CC, the original anti-load driving signal ALDX can be coupled to the output end of the anti-load driving circuit 1000, and carried at the level of the voltage VH, and output by the anti-load driving circuit 1000, such as Fig.10 shown.

[0095] Fig.11A A detailed implementation of the anti-load drive generator 1004 is shown. Fig.11AAs shown, the anti-load drive generator 1004 includes voltage regulators 1102 and 1104, capacitors C1 and C2, and a switch module 1110. The voltage regulator 1102 can be used to generate and output a voltage V1, and the voltage regulator 1104 can be used to generate and output a voltage V2, wherein the value of the voltage V1 is higher than the value of the voltage V2 by an appropriate difference. The capacitors C1 and C2 are respectively coupled to the output ends of the voltage regulators 1102 and 1104 to improve the stability of the voltages V1 and V2. The switch module 1110 can receive the voltages V1 and V2, and alternately output the voltages V1 and V2 through the control of the switch to generate the original anti-load drive signal ALDX. In this example, the original anti-load drive signal ALDX can be a square wave signal that switches between the levels of the voltages V1 and V2.

[0096] Fig. 11B Another embodiment of the anti-load drive generator 1004 is shown. Fig. 11B As shown, the anti-load driving generator 1004 includes a digital-to-analog converter (DAC) 1150. The digital-to-analog converter 1150 can receive a digital code DIG sequence and convert the digital code DIG into an analog voltage to generate and output the original anti-load driving signal ALDX accordingly. In this example, the original anti-load driving signal ALDX can have any feasible waveform according to the received digital code DIG.

[0097] As mentioned above, the anti-load drive circuit may be included in, for example, Figure 8 The fingerprint touch display integrated circuit 802 shown, or included in, for example Fig. 9 In another embodiment, a load-resistance driving circuit can also be implemented in the fingerprint sensor of the display screen. Fig.12 , Fig.12 FIG. 1 is a schematic diagram of another display system 1200 according to an embodiment of the present invention. The circuit structure of the display system 1200 is similar to the circuit structure of the display system 80, so signals or components with similar functions are represented by the same symbols. Fig.12 As shown, the difference between the display system 1200 and the display system 80 is that in the display system 1200, the anti-load driving circuit 1250 is implemented in the fingerprint sensor on the display screen 804. The anti-load driving circuit 1250 is coupled to the fingerprint sensing pixel array and is operated by a control signal CTRL received from the fingerprint touch display integrated circuit 802. For example, the anti-load driving circuit 1250 may have a structure similar to Fig.10The structure of the anti-load driving circuit 1000 is shown, wherein when the anti-load driving generator 1004 receives the control signal CTRL to be enabled or triggered, it can output the original anti-load driving signal ALDX. Alternatively, the control signal CTRL can be the original anti-load driving signal ALDX, which can be used to drive the anti-load driving circuit 1250 to output the anti-load driving signal at a predetermined voltage level.

[0098] In another embodiment, the configuration of including the anti-load driving circuit in the fingerprint sensor can also be combined with the following Fig. 9 The operation of the dual-chip structure having a fingerprint sensing circuit and a touch display driving integrated circuit is similar to the description in the previous paragraph and will not be repeated here.

[0099] It should also be noted that the purpose of the embodiments of the present invention is to provide a control method for an optical fingerprint sensor and its related control circuit and optical fingerprint sensor. Those skilled in the art may make modifications or changes accordingly, but are not limited to this. Those skilled in the art should be aware that there may be various types of pixel structures on the fingerprint sensing layer of the display screen, and the pixel structure described in this specification is only one of the various implementations of the fingerprint sensing pixel. For example, an additional switch may be provided between the optoelectronic component and the storage capacitor to adjust the exposure time by controlling the operation of the switch. In this case, the anti-load drive signal should be applied according to the structure of the fingerprint sensing pixel.

[0100] besides, Figure 4 The arrangement of the row (horizontal) control signal lines, column (vertical) sensing lines, and column (vertical) voltage source lines shown is only one of many embodiments of the present invention. In another embodiment, the sensing lines and the voltage source lines may be arranged along the horizontal direction, and the control signal lines may be arranged along the vertical direction; or, some control signal lines may be arranged along the horizontal direction and other control signal lines may be arranged along the vertical direction. The row / column control circuit for the fingerprint sensing pixel can be arranged accordingly. For example, if the sensing line is a row sensing line arranged along the horizontal direction, the row control circuit may include a sensor module for receiving the sensing signal. The arrangement of these wires and control circuits should not be used to limit the scope of the present invention.

[0101] Furthermore, the method of applying an anti-load driving signal to the fingerprint sensing pixel can also be applied to various types of display screens that integrate touch and fingerprint sensing functions, such as a liquid crystal display (LCD) panel, an organic light-emitting diode (OLED) panel, or a plasma display panel (PDP). For liquid crystal displays, the anti-load driving operation can be applied to in-cell or on-cell or out-cell liquid crystal displays. It should be noted that the anti-load driving signal is more suitable for an in-cell touch screen with a fingerprint sensing function because the touch sensing layer and the fingerprint sensing layer are closer in the in-cell structure, but the implementation method should not be limited to this.

[0102] The above operations of the optical fingerprint sensor and the fingerprint control circuit can be summarized into a process 1300, such as Fig.13 The process 1300 may be implemented in a fingerprint control circuit or an anti-load driving circuit to be applied to an optical fingerprint sensor integrated with a touch controller and having a plurality of fingerprint sensing pixels, wherein each pixel may include a first control signal line and a second control signal line, and coupled to a first voltage source line, a second voltage source line and a sensing line, such as Figure 3 The pixel structure shown in Figure 2 is as follows. Fig.13 As shown, process 1300 includes the following steps:

[0103] Step 1302: Start.

[0104] Step 1304: When the touch controller is in a touch operation period, at least one of the first control signal line, the second control signal line, the first voltage source line, the second voltage source line, and the sensing line applies an anti-load driving signal.

[0105] Step 1306: End.

[0106] It should be noted that the first control signal line, the second control signal line, the first voltage supply line, the second voltage supply line, and the sensing line that are not applied with an anti-load driving signal can be controlled to be in a floating state. Furthermore, the fingerprint control circuit can also adopt a control method based on floating or floating connection, such as Fig.14 As shown in the process 1400, the process 1400 includes the following steps:

[0107] Step 1402: Start.

[0108] Step 1404: When the touch controller is in a touch operation period, the first control signal line, the second control signal line, the first voltage supply line, the second voltage supply line, and the sensing line are all in a floating state.

[0109] Step 1406: End.

[0110] The detailed implementation and variations of processes 1300 and 1400 can be found in the description of the preceding paragraphs and will not be elaborated here.

[0111] In summary, the embodiments of the present invention provide a control method and a control circuit thereof and an optical fingerprint sensor that can be used for an optical fingerprint sensor. The optical fingerprint sensor can be integrated into a touch screen, wherein one of the touch sensing layer and the fingerprint sensing layer can be superimposed on the other layer, and the two layers are close to each other, so that the coupling capacitance between the touch sensing layer and the fingerprint sensing layer causes a huge capacitive load. During the touch operation, the touch signal will form a capacitive load on the wire of the fingerprint sensing pixel. In order to eliminate or reduce the capacitive load, an anti-load driving signal can be applied to the wire of the fingerprint sensing pixel. The anti-load driving signal can be used to drive this wire, wherein the frequency, phase and / or amplitude of the anti-load driving signal are substantially the same as the frequency, phase and / or amplitude of the touch signal, respectively. Alternatively or additionally, the anti-load driving operation can also be achieved by controlling the target node of the fingerprint sensing pixel to enter a floating state. The anti-load driving operation can be performed during the touch operation of the touch controller and / or during the exposure period of the optical fingerprint sensor. The wires in the fingerprint sensing pixel for receiving the anti-load driving signal may include wires directly coupled to the storage capacitor in the pixel and wires coupled to the storage capacitor through a transistor. Under the anti-load driving operation, the voltage across the storage capacitor will be free from interference from the touch signal, thereby maintaining the accuracy of the fingerprint sensing signal.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A control method for an optical fingerprint sensor and a touch controller, wherein the optical fingerprint sensor comprises a plurality of pixels, wherein each pixel has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line and a sensing line, the control method comprising: When the touch controller is in a touch operation period, at least one of the first control signal line, the second control signal line, the first voltage source line, the second voltage source line, and the sensing line applies an anti-load driving signal.

2. The control method according to claim 1, characterized in that: The anti-load driving signal is applied during an exposure period of the optical fingerprint sensor.

3. The control method according to claim 1, characterized in that: The first control signal line, the second control signal line, the first voltage supply line, the second voltage supply line, and the sensing line to which the anti-load driving signal is not applied are maintained in a floating state.

4. The control method according to claim 1, characterized in that: A control circuit of the optical fingerprint sensor and the touch controller are integrated with a display driving device, and the anti-load driving signal includes a pulse, the frequency and phase of the pulse are substantially the same as the frequency and phase of a touch signal of the touch controller.

5. The control method according to claim 4, characterized in that: The amplitude of the anti-load driving signal is substantially the same as the amplitude of the touch signal.

6. A control method for an optical fingerprint sensor and a touch controller, wherein the optical fingerprint sensor comprises a plurality of pixels, wherein each pixel has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line and a sensing line, the control method comprising: When the touch controller is in a touch operation period, the first control signal line, the second control signal line, the first voltage supply line, the second voltage supply line, and the sensing line are all in a floating state.

7. A control circuit for controlling an optical fingerprint sensor, the optical fingerprint sensor comprising a plurality of pixels, wherein each pixel has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line and a sensing line, the control circuit is integrated with a touch controller to perform the following operations: When the touch controller is in a touch operation period, at least one of the first control signal line, the second control signal line, the first voltage source line, the second voltage source line, and the sensing line applies an anti-load driving signal.

8. The control circuit according to claim 7, characterized in that: The control circuit is used for applying the anti-load driving signal during an exposure period of the optical fingerprint sensor.

9. The control circuit according to claim 7, characterized in that: The first control signal line, the second control signal line, the first voltage supply line, the second voltage supply line, and the sensing line to which the anti-load driving signal is not applied are maintained in a floating state.

10. The control circuit according to claim 7, characterized in that: The second control signal line is coupled to a first end of a storage capacitor of a corresponding pixel among the plurality of pixels.

11. The control circuit according to claim 10, characterized in that: A second terminal of the storage capacitor is coupled to a first transistor and a second transistor in the corresponding pixel.

12. The control circuit according to claim 11, characterized in that: The first transistor is also coupled to the first control signal line and the first voltage source line.

13. The control circuit according to claim 11, characterized in that: The second transistor is also coupled to the second voltage source line.

14. The control circuit according to claim 11, characterized in that: The second transistor is also coupled to the sensing line through a third transistor.

15. The control circuit according to claim 7, characterized in that: The optical fingerprint sensor is in an exposure period.

16. The control circuit according to claim 10, characterized in that: The storage capacitor is coupled to a photoelectric component.

17. The control circuit according to claim 7, characterized in that: The control circuit, the touch controller and a display driving device are integrated with each other, and the anti-load driving signal includes a pulse, the frequency and phase of the pulse are substantially the same as the frequency and phase of a touch signal of the touch controller.

18. The control circuit according to claim 17, characterized in that: The amplitude of the anti-load driving signal is substantially the same as the amplitude of the touch signal.

19. The control circuit according to claim 7, characterized in that: The control circuit applies the anti-load driving signal according to the notification received from the touch controller.

20. A control circuit for controlling an optical fingerprint sensor, the optical fingerprint sensor comprising a plurality of pixels, wherein each pixel has a first control signal line and a second control signal line, and each pixel is also coupled to a first voltage source line, a second voltage source line and a sensing line, the control circuit is integrated with a touch controller to perform the following operations: When the touch controller is in a touch operation period, the first control signal line, the second control signal line, the first voltage supply line, the second voltage supply line, and the sensing line are all in a floating state.

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