Readout integrated circuit

Abstract

A readout integrated circuit is configured to read a sensing signal from an optical sensing panel. The optical sensing panel includes a sensor array for fingerprint sensing. The readout integrated circuit includes a plurality of input terminals, a discharge circuit, and a control circuit. The input terminals are for coupling to output terminals of the optical sensing panel. The discharge circuit is coupled to one of the plurality of input terminals and is configured to discharge one of the plurality of output terminals of the optical sensing panel by a current during a readout. The readout integrated circuit reads a voltage of the output terminal as the sensing signal. The control circuit is coupled to the discharge circuit and is configured to output at least one control signal to control an operation period of the discharge circuit.

Description

Technical Field

[0001] The present invention relates to an electronic circuit, and more particularly, to a read integrated circuit. Background Art

[0002] In an in-display fingerprint sensing panel having an optical sensor, an optical sensor array is fabricated on a lower substrate of a display panel. The optical sensors are configured as a sensor array for sensing reflected light of a finger on the fingerprint sensing panel to generate fingerprint sensing signals, and a fingerprint read integrated circuit receives the fingerprint sensing signals through sensing lines and output terminals of the fingerprint sensing panel. The fingerprint read integrated circuit is configured to read the fingerprint sensing signals and further transmit the fingerprint sensing signals converted into digital sensing data to a processor unit for fingerprint recognition. For example, a handheld device such as a mobile phone includes a touch display screen having an in-display fingerprint sensing panel, and the fingerprint read integrated circuit of the mobile phone transmits fingerprint sensing data to an application processor. The application processor then performs image processing on the fingerprint sensing data to generate a fingerprint image for fingerprint recognition.

[0003] However, when the size of the fingerprint sensing panel is large, the transmission distances from optical sensors at different positions (referred to as fingerprint sensing pixels) to the output terminals of the fingerprint sensing panel are different. Some optical sensors are closer to the corresponding output terminals and transmit fingerprint sensing signals over a shorter distance, while other optical sensors are farther from the corresponding output terminals and transmit fingerprint sensing signals over a longer distance. For the optical sensors that are farther from the corresponding output terminals, the fingerprint sensing signals are transmitted on sensing lines with a large load. This may have a negative impact on the fingerprint sensing signals. For example, it may cause the settling time of the fingerprint sensing signals to be too long, thereby degrading the quality of the fingerprint image generated based on the fingerprint sensing signals. Summary of the Invention

[0004] The present invention relates to a read integrated circuit in which the settling time of fingerprint sensing signals is short, which can improve the quality of fingerprint images.

[0005] Embodiments of the present invention provide a read integrated circuit configured to read sensing signals from an optical sensing panel. The optical sensing panel includes a sensor array for fingerprint sensing. The read integrated circuit includes a plurality of input terminals, a first discharge circuit, and a control circuit. The plurality of input terminals are for coupling to a plurality of output terminals of the optical sensing panel. The first discharge circuit is coupled to one of the plurality of input terminals. The first discharge circuit is configured to discharge one of the plurality of output terminals of the optical sensing panel through a first current during a readout. The read integrated circuit reads the voltage of the output terminal as the sensing signal. The control circuit is coupled to the first discharge circuit. The control circuit is configured to output at least one control signal to control the operation of the first discharge circuit during the operation.

[0006] In an embodiment of the present invention, the first discharge circuit includes a first current source. The first current source is controlled by a first voltage to generate the first current.

[0007] In an embodiment of the present invention, the first current source includes a first terminal, a second terminal, and a control terminal. The first current is transmitted from the first terminal to the second terminal. The first terminal of the first current source is coupled to the output terminal. The second terminal of the first current source is coupled to a reference voltage. The control terminal of the first current source is coupled to the first voltage.

[0008] In an embodiment of the present invention, the at least one control signal includes a first control signal and a second control signal. The first discharge circuit further includes a first switching element and a second switching element. The first switching element is controlled by the first control signal. The first switching element includes a first terminal, a second terminal, and a control terminal. The first terminal of the first switching element is coupled to the first voltage. The second terminal of the first switching element is coupled to the control terminal of the first current source. The control terminal of the first switching element is coupled to the first control signal. The second switching element is controlled by the second control signal. The second switching element includes a first terminal, a second terminal, and a control terminal. The first terminal of the second switching element is coupled to the control terminal of the first current source. The second terminal of the second switching element is coupled to the reference voltage. The control terminal of the second switching element is coupled to the second control signal.

[0009] In an embodiment of the present invention, the second control signal is inverted from the first control signal. When the first switching element is turned on, the second switching element is not turned on. When the second switching element is turned on, the first switching element is not turned on.

[0010] In an embodiment of the present invention, the at least one control signal includes a first control signal. The first discharge circuit further includes a first switching element. The first switching element is controlled by the first control signal. The first switching element includes a first terminal, a second terminal, and a control terminal. The first terminal of the first switching element is coupled to the output terminal. The second terminal of the first switching element is coupled to the first terminal of the first current source. The control terminal of the first switching element is coupled to the first control signal.

[0011] In an embodiment of the present invention, the first discharge circuit further includes a first switching element and a diode element. The first switching element is controlled by the first control signal. The first switching element includes a first terminal, a second terminal, and a control terminal. The first terminal of the first switching element is coupled to the first voltage. The second terminal of the first switching element is coupled to the control terminal of the first current source. The control terminal of the first switching element is coupled to the first control signal. The diode element includes an anode terminal and a cathode terminal. The anode terminal of the diode element is coupled to the output terminal. The cathode terminal of the diode element is coupled to the first terminal of the first switching element.

[0012] In an embodiment of the present invention, the readout integrated circuit further includes a second discharge circuit. The second discharge circuit is coupled to the output terminal of the optical sensing panel. The second discharge circuit is configured to discharge the output terminal through a second current during the readout.

[0013] In an embodiment of the present invention, the second discharge circuit includes a second current source. The second current source is controlled by a second voltage to generate the second current.

[0014] In an embodiment of the present invention, the second current source includes a first terminal, a second terminal, and a control terminal. The second current is transmitted from the first terminal to the second terminal. The first terminal of the second current source is coupled to the output terminal. The second terminal of the second current source is coupled to the reference voltage. The control terminal of the second current source is coupled to the second voltage.

[0015] In an embodiment of the present invention, a precharge circuit is coupled to the output terminal of the optical sensing panel. The precharge circuit is configured to charge the output terminal to an initial voltage during precharge. The precharge period is earlier than the readout period.

[0016] In an embodiment of the present invention, the pre-charge circuit includes a third switching element. The third switching element is controlled by a third voltage. The third switching element includes a first terminal, a second terminal, and a control terminal. The first terminal of the third switching element is coupled to the output terminal. The second terminal of the third switching element is coupled to the second discharge circuit. The control terminal of the third switching element is coupled to the third voltage.

[0017] In an embodiment of the present invention, the second discharge circuit and the pre-charge circuit are provided in the readout integrated circuit.

[0018] In an embodiment of the present invention, the second discharge circuit and the pre-charge circuit are provided in a display panel in which the sensor array is embedded.

[0019] In an embodiment of the present invention, the first current is greater than or equal to the second current.

[0020] In an embodiment of the present invention, the output terminal is pre-charged to a voltage level close to the highest input voltage of the analog-to-digital converter during the pre-charge period.

[0021] Embodiments of the present invention provide a readout integrated circuit configured to read a sensing signal from an optical sensing panel. The optical sensing panel includes a sensor array for fingerprint sensing. The readout integrated circuit includes a plurality of input terminals, a first charging circuit, and a control circuit. The plurality of input terminals are for coupling to a plurality of output terminals of the optical sensing panel. The first charging circuit is coupled to one of the plurality of input terminals. The first charging circuit is configured to charge one of the plurality of output terminals of the optical sensing panel with a first current during a readout. The readout integrated circuit reads the voltage of the output terminal as the sensing signal. The control circuit is coupled to the first charging circuit. The control circuit is configured to output at least one control signal to control the operation period of the first charging circuit.

[0022] In an embodiment of the present invention, the readout integrated circuit further includes a second charging circuit. The second charging circuit is coupled to the output terminal of the optical sensing panel. The second charging circuit is configured to charge the output terminal with a second current during the readout.

[0023] In an embodiment of the present invention, a pre-discharge circuit is coupled to the output terminal of the optical sensing panel. The pre-discharge circuit is configured to charge the output terminal to an initial voltage during a pre-discharge period. The pre-charge period is earlier than the readout period.

[0024] To make the above content easier to understand, several embodiments with accompanying drawings are elaborated in detail below. Description of the Drawings

[0025] This document includes drawings to provide a further understanding of the present disclosure, and the drawings are incorporated into and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with this description, are used to explain the principles of the present disclosure.

[0026] Figure 1 is a schematic block diagram of a read integrated circuit and an optical sensing panel according to an embodiment of the present invention.

[0027] Figure 2 is according to an embodiment of the present invention Figure 1 schematic block diagram of the read integrated circuit shown in

[0028] Figure 3 is a schematic diagram of a plurality of sensor circuits according to an embodiment of the present invention, which shows a column of sensor circuits of a sensor array of an optical sensing panel configured in Figure 1

[0029] Figure 4 is a schematic block diagram of a read integrated circuit according to another embodiment of the present invention.

[0030] Figure 5 is a schematic diagram of a sensor circuit and a read integrated circuit according to an embodiment of the present invention.

[0031] Figure 6 is a waveform diagram of the voltage at an output terminal during different operations according to an embodiment of the present invention.

[0032] Figure 7 is a waveform diagram of the voltage at an output terminal during different operations according to another embodiment of the present invention.

[0033] Figure 8 is a schematic diagram of a sensor circuit and a read integrated circuit according to another embodiment of the present invention.

[0034] Figure 9 is a schematic diagram of a sensor circuit and a read integrated circuit according to another embodiment of the present invention.

[0035] Figure 10 is a flowchart of a method for operating a read integrated circuit according to an embodiment of the present invention.

[0036] Figure 11 is a schematic block diagram of a read integrated circuit according to another embodiment of the present invention.

[0037] Figure 12 ​Schematic block diagram of a readout integrated circuit according to another embodiment of the present invention.

[0038] [Description of symbols]

[0039] 100, 400, 400A, 400B, 400C, 600, 700: Readout integrated circuit

[0040] 110, 110A, 110B, 110C: First discharge circuit

[0041] 112: First current source

[0042] 114: First switching element

[0043] 116: Second switching element

[0044] 118: Diode element

[0045] 120: Second discharge circuit

[0046] 122: Second current source

[0047] 130: Control circuit

[0048] 200: Optical sensing panel

[0049] 202: Output terminal

[0050] 204: Column output line

[0051] 210: Sensor circuit

[0052] 500: Precharge circuit

[0053] 510: Third switching element

[0054] 610, 710: First charge circuit

[0055] 720: Second charge circuit

[0056] C: Capacitor

[0057] GND: Ground voltage

[0058] I1: First current

[0059] I2: Second current

[0060] M RS : Reset transistor

[0061] M SEL : Selection transistor

[0062] M SF : Transistor

[0063] MTG : Transfer transistor

[0064] Nr: Node

[0065] PD: Photodiode

[0066] S100, S110: Steps

[0067] SR: Signal range

[0068] T1: Pre-charge period

[0069] T2: Read period

[0070] V1: Highest input voltage

[0071] Vb1: First voltage

[0072] Vb2: Second voltage

[0073] Vctrl: Control signal

[0074] Vctrl_pre: Third control signal

[0075] VDD: High voltage

[0076] V HD : First control signal

[0077] V HDB : Second control signal

[0078] Vi: Initial voltage

[0079] Vout: Output voltage / Voltage

[0080] Vpre: Pre-charge voltage

[0081] Vs: Sensing voltage Detailed implementation manners

[0082] Embodiments are provided below to elaborate on the present disclosure in detail. However, the present disclosure is not limited to the provided embodiments, and the provided embodiments can be appropriately combined. The term "coupling / coupled" or "connecting / connected" used in this specification (including the claims) of this application can refer to any direct or indirect connection method. For example, "The first device is coupled to the second device" should be interpreted as "The first device is directly connected to the second device" or "The first device is indirectly connected to the second device through other devices or connection methods". Additionally, the term "signal" can refer to current, voltage, charge, temperature, data, electromagnetic waves, or any one or more signals.

[0083] Figure 1FIG. is a schematic block diagram of a read integrated circuit and an optical sensing panel according to an embodiment of the present invention. In this embodiment, the optical sensing panel is a fingerprint sensing panel under the display panel. Figure 2 is according to an embodiment of the present invention Figure 1 schematic block diagram of the read integrated circuit shown in. Figure 3 is a schematic diagram of a plurality of sensor circuits according to an embodiment of the present invention, which shows the configuration in Figure 1 a column of sensor circuits of the sensor array of the optical sensing panel in.

[0084] Referring to Figures 1 to 3 , the optical sensing panel 200 includes a sensor array, a plurality of sensing lines 204, and a plurality of output terminals 202. The sensor array is formed by a plurality of sensor circuits 210 as sensing pixels. The output terminals 202 can output fingerprint sensing signals. Each column of the sensor circuits is coupled to a respective sensing line 204. The number of output terminals 202 of the optical sensing panel 200 can be the same as or less than the number of sensing lines 204. The read integrated circuit 100 includes a plurality of input terminals 206. The input terminals 206 are configured to be coupled to some of the output terminals 202 in the optical sensing panel 200. It should be noted that for the current fingerprint sensing operation, the number of fingerprint sensing signals processed by the read integrated circuit 100 at the same time is determined based on the circuit design of the read integrated circuit 100. The processing number can be related to the number of analog front-end circuits in the read integrated circuit 100, but is not limited thereto. The analog front-end circuits can process the received fingerprint sensing signals in parallel. The positions and numbers of the sensor circuits 210 performing the current fingerprint sensing operation may not be all the sensor circuits in the optical sensing panel 200. The sensor circuits 210 performing the current fingerprint sensing operation can be a preset part of the sensor array, or determined according to the touch position regarding the touch event. In one embodiment, the optical sensing panel 200 has 1080 columns of sensor circuits, 1080 sensing lines, and 1080 output terminals, and the read integrated circuit 100 includes 250 input terminals, and only 250 of the 1080 output terminals of the optical sensing panel 200 are respectively coupled to the 250 input terminals in the read integrated circuit 100. Therefore, at the same time, the fingerprint sensing signals generated from 250 sensor circuits in the same row can be transmitted to the read integrated circuit 100 through 250 output terminals.

[0085] In Figure 3In this case, only the sensor circuit 210 coupled to the same column of sensing lines 204 is shown as an example, but the present invention is not limited thereto. From the perspective of the read integrated circuit 100, the input terminals 206 of the read integrated circuit 100 are coupled to a part of the sensing lines 204 through a part of the output terminals 202 of the optical sensing panel 200. The read integrated circuit 100 is configured to read the output voltage Vout of the output terminals 202. The output voltage Vout is ideally expected to be equal to the output voltage of the sensor circuit (which is referred to as the sensing voltage Vs). However, the farther the distance between the sensor circuit and the output terminals 202, the greater the resistance-capacitance load on the sensing lines 204, which will make the time for the output voltage Vout of the output terminals 202 to stabilize to the sensing voltage Vs longer. It should be noted that regarding the output voltage Vout of the output terminals 202 during the reading period, the output voltage Vout of the output terminals 202 at the start of the reading period can be referred to as the initial output voltage. At the start of the reading period, if the initial output voltage Vout is greater than the sensing voltage Vs, the process from the initial output voltage Vout to the sensor circuit actually outputting the sensing voltage Vs can be regarded as a discharging process. Here, the initial output voltage Vout of the output terminals 202 at the start of the reading period can be determined according to the circuit design of the read integrated circuit 100. In Figure 5 and Figure 9 this case, a discharging process is used as an embodiment for the output voltage Vout to stabilize to the sensing voltage Vs. In other embodiments, such as Figure 11 and Figure 12 , at the start of the reading period, if the initial output voltage Vout is less than the sensing voltage Vs, the process from the initial output voltage Vout to the sensor circuit actually outputting the sensing voltage Vs can be regarded as a charging process. On the other hand, the initial output voltage can be determined according to a pre-charging process or a pre-discharging process, which will be described in detail later.

[0086] The read integrated circuit 100 further includes a first discharging circuit 110 and a control circuit 130. The first discharging circuit 110 is coupled to one of the input terminals 206 as shown in Figure 2 this case. That is, the first discharging circuit 110 is coupled to one of the output terminals 202 among some output terminals 202 in the optical sensing panel 200 through the input terminal 206. In one embodiment, since the first discharging circuit 110 can serve multiple output terminals 202, the first discharging circuit 110 can be coupled to multiple input terminals 206 and then coupled to the corresponding output terminals 202 through the multiple input terminals 206. The first discharging circuit 110 is configured to discharge during the reading period through as shown in Figure 5The first current I1 shown discharges the output terminal 202 or the plurality of output terminals 202. The read integrated circuit 100 reads the output voltage Vout of the output terminal 202 as a sense signal, or reads the output voltages Vout of the plurality of output terminals 202 as a sense signal. The control circuit 130 is coupled to the first discharge circuit 110 and is configured to output at least one control signal Vctrl to control the operation period of the first discharge circuit 110.

[0087] Figure 4 is a schematic block diagram of a read integrated circuit according to another embodiment of the present invention. Referring to Figure 2 and Figure 4 , the read integrated circuit 400 of this embodiment is similar to Figure 2 the read integrated circuit 100 shown, and the main difference between the read integrated circuit 400 and the read integrated circuit 100 is, for example, that the read integrated circuit 400 further includes a second discharge circuit 120. The second discharge circuit 120 is coupled to the output terminal 202 (or the plurality of output terminals 202) of the optical sensing panel 200 (as shown in Figure 3 ). The second discharge circuit 120 is configured to discharge the output terminal 202 (or the plurality of output terminals 202) through a second current I2 (as shown in Figure 5 ) during reading.

[0088] Figure 5 is a schematic diagram of a sensor circuit and a read integrated circuit according to an embodiment of the present invention. Figure 5 is an embodiment in which the output voltage Vout is stabilized to the sense voltage Vs by a discharge process. Referring to Figure 5 , the read integrated circuit 400A includes a first discharge circuit 110A, a second discharge circuit 120, and a control circuit 130. In addition, a precharge circuit 500 is coupled to the output terminal 202 of the optical sensing panel 200. The circuit structures of the sensor circuit 210, the first discharge circuit 110A, the second discharge circuit 120, and the precharge circuit 500 are further shown in Figure 5 . However, its circuit structure is not intended to limit the present invention. In another embodiment, it is an embodiment in which the output voltage Vout is stabilized to the sense voltage Vs by a charging process. The first discharge circuit 110A can be replaced by a first charge circuit. The first charge circuit includes similar switching elements and a current source that provides a current in a direction opposite to that of the first current I1 to charge the output terminal 202, and the reference voltage is the power supply voltage. The control circuit 130 can also be used to control the operation period of the first charge circuit. The second discharge circuit 120 can be replaced by a second charge circuit, and the precharge circuit 500 can be replaced by a predischarge circuit. Similarly, Figure 8 and Figure 9It is also possible to replace its discharge circuit and pre - charge circuit with a similar circuit design method based on an embodiment where the charging process is used as the output voltage Vout stabilizes to the sensed voltage Vs.

[0089] An active pixel structure with four transistors is taken as an example of the sensor circuit 210. During reset, the reset transistor M RS is turned on, and the voltage at node Nr is pulled up to the high voltage VDD to turn off the source - follower formed by the transistor M SF During reset, the output voltage Vout of the output terminal 202 is discharged. During exposure, the photosensing mechanism is implemented, and the photodiode PD generates current. During readout, the selection transistor M SEL is turned on, and then the reset transistor M RS is turned on again. Next, the transfer transistor M TG is turned on, and the sensed voltage regarding the fingerprint information is transmitted to node Nr. Thus, the voltage at node Nr changes from the high voltage VDD to the sensed voltage, which is lower than the high voltage VDD. During readout, the stable output voltage Vout is determined by the voltage at node Nr. For example, when the voltage at node Nr during readout is a stable voltage of 2V, the stable output voltage Vout is close to the voltage 2V - Vgs, where Vgs is the voltage difference between the gate terminal and the source terminal of the source - follower formed by the transistor M SF Therefore, the output voltage Vout is read during readout and used as the sensing signal. Whether the output terminal 202 is discharged or charged depends on the initial output voltage of the output terminal 202 at the start of the read period. In Figure 5 the embodiment, the initial output voltage is determined by the pre - charge voltage Vpre during the pre - charge process.

[0090] The first discharge circuit 110A includes a first current source 112, a first switching element 114, and a second switching element 116. The first current source 112 is controlled by a first voltage Vb1 to generate a first current I1. The first current source 112 includes a first terminal, a second terminal, and a control terminal. The first current I1 is transmitted from the first terminal to the second terminal. The first terminal of the first current source 112 is coupled to the output terminal 202. The second terminal of the first current source 112 is coupled to a reference voltage. The control terminal of the first current source 112 is coupled to the first voltage Vb1. In this embodiment, the reference voltage can be the ground voltage GND, but the present invention is not limited thereto.

[0091] The first switching element 114 is controlled by a first control signal V HDControl. The first switching element 114 includes a first terminal, a second terminal, and a control terminal. The first terminal of the first switching element 114 is coupled to the first voltage Vb1. The second terminal of the first switching element 114 is coupled to the control terminal of the first current source 112. The control terminal of the first switching element 114 is coupled to the first control signal V HD .

[0092] The second switching element 116 is controlled by the second control signal V HDB . The second switching element 116 includes a first terminal, a second terminal, and a control terminal. The first terminal of the second switching element 116 is coupled to the control terminal of the first current source 112. The second terminal of the second switching element 116 is coupled to the reference voltage GND. The control terminal of the second switching element 116 is coupled to the second control signal V HDB . In this embodiment, the second control signal V HDB is inverted from the first control signal V HD . The second control signal V HDB is the inverted signal of the first control signal V HD . When the first switching element 114 is turned on by the first control signal V HD , the second switching element 116 is not turned on. When the second switching element 116 is turned on by the second control signal V HDB , the first switching element 114 is not turned on. The second switching element 116 can be turned on to ensure that the first current source 112 is turned off.

[0093] The second discharge circuit 120 is coupled to the output terminal 202 of the optical sensing panel 200. The second discharge circuit 120 is configured to discharge the output terminal 202 through the second current I2 during readout. The second discharge circuit 120 includes a second current source 122. The second current source 122 is controlled by the second voltage Vb2 to generate the second current I2. The second current source 122 includes a first terminal, a second terminal, and a control terminal. The second current I2 is transmitted from the first terminal to the second terminal. The first terminal of the second current source 122 is coupled to the output terminal 202. The second terminal of the second current source 122 is coupled to the reference voltage GND. The control terminal of the second current source 122 is coupled to the second voltage Vb2.

[0094] In one embodiment, the first current I1 is greater than the second current I2, such that the discharging operation is dominated by the first discharge circuit 110A, but the present invention is not limited thereto. In another embodiment, the first current I1 may be equal to the second current I2. The power consumption of the optical sensing panel 200 can be reduced because the power consumption of the first current source 112 belongs to the power consumption of the readout integrated circuit 100 and does not belong to the power consumption of the optical sensing panel 200.

[0095] The control circuit 130 is coupled to the first discharge circuit 110A. The control circuit 130 outputs at least one control signal during the operation of the first discharge circuit 110A. For example, the control circuit 130 may output a first control signal V HD and a second control signal V HDB to control the operation of the first discharge circuit 110A. The operation period of the first discharge circuit 110A indicates the period during which the first discharge circuit 110A discharges the output terminal 202 of the optical sensing panel 200.

[0096] In one embodiment, the control circuit 130 may include a controller implemented by one or more of the following processing elements, for example: an array of logic gates, an arithmetic logic unit, a digital signal processor, a microcomputer, a programmable logic controller, a field programmable gate array, a programmable logic array, a microprocessor, or any other device or combination of devices configured to respond and execute instructions in a defined manner to achieve a desired result.

[0097] The precharge circuit 500 is coupled to the output terminal 202 of the optical sensing panel 200. The precharge circuit 500 is configured to charge the output terminal 202 to an initial voltage during precharge. The precharge period is earlier than the read period. The precharge circuit 500 includes a third switching element 510. The third switching element 510 is controlled by a third control signal Vctrl_pre. The third switching element 510 includes a first terminal, a second terminal, and a control terminal. The first terminal of the third switching element 510 is coupled to the output terminal 202. The second terminal of the third switching element 510 is coupled to the second discharge circuit 120. The control terminal of the third switching element 510 is coupled to the precharge voltage Vpre. When the third switching element 510 is turned on by the third control signal Vctrl_pre, the output terminal 202 is charged to the initial voltage during precharge. The third control signal Vctrl_pre can be output from the control circuit 130 or other external control circuits.

[0098] In the present embodiment, the second discharge circuit 120 and the precharge circuit 500 are provided in the readout integrated circuit 400A. That is, the readout integrated circuit 400A includes the second discharge circuit 120 and the precharge circuit 500 and is implemented in a single semiconductor chip or circuit system, but the present invention is not limited thereto. In one embodiment, the second discharge circuit 120, the precharge circuit 500, and the readout integrated circuit 400A may be implemented in separate devices. For example, the second discharge circuit 120 and the precharge circuit 500 are provided in a display panel in which the optical sensing panel 200 is embedded.

[0099] Figure 6 is a waveform diagram of the voltage at the output terminal during different operations according to an embodiment of the present invention. Refer to Figure 5 andFigure 6 , during the pre-charge period T1, the pre-charge circuit 500 charges the output terminal 202 to the initial voltage Vi. The first discharge circuit 110A and the second discharge circuit 120 discharge the output terminal 202 during the read period T2, thereby making the discharge speed of the output voltage Vout faster. The stabilization time of the fingerprint sensing signal (i.e., the output voltage Vout) is short, which can improve the quality of the fingerprint image. The stabilization time is the time required for the output voltage Vout to reach and maintain within a preset voltage range. The read period T2 is the operation period of the first discharge circuit 110A, and the time span of the operation period is controlled by the first control signal V HD Control.

[0100] In this embodiment, the output voltage Vout can be transmitted to an analog front-end circuit (not shown) in the read integrated circuit 400, and then transmitted to an analog-to-digital converter (not shown). Alternatively, if there is no analog front-end circuit, the output voltage Vout can be directly transmitted to the analog-to-digital converter (not shown) in the read integrated circuit 400 without being processed by the analog front-end circuit. The signal range SR is the input voltage range of the analog-to-digital converter. The output terminal 202 is pre-charged to a voltage level lower than the highest input voltage V1 of the analog-to-digital converter during the pre-charge period, but the present invention is not limited thereto. In one embodiment, the output terminal 202 can be pre-charged to a voltage level close to the highest input voltage V1 of the analog-to-digital converter during the pre-charge period.

[0101] Figure 7 is a waveform diagram of the voltage at the output terminal during different operation periods according to another embodiment of the present invention. Referring to Figure 5 And Figure 7 , the output terminal 202 is pre-charged to the initial voltage Vi, and during the pre-charge period T1, the voltage level of the initial voltage Vi is close to the highest input voltage V1 of the analog-to-digital converter. The first discharge circuit 110A and the second discharge circuit 120 further discharge the output terminal 202 during the read period T2, thereby making the discharge speed of the output voltage faster. In addition, the pre-charge operation can be performed during the reset period, before the read period (meaning the exposure period), or at an early stage of the read period before the selection transistor M SEL Is turned on.

[0102] Figure 8 is a schematic diagram of a sensor circuit and a read integrated circuit according to another embodiment of the present invention. Referring to Figure 5 And Figure 8 , the read integrated circuit 400B of this embodiment is similar to Figure 5The readout integrated circuit 400A is shown, and the main difference between the readout integrated circuit 400B and the readout integrated circuit 400A lies, for example, in the circuit structure of the first discharge circuit 110B.

[0103] Specifically, the first discharge circuit 110B includes a first current source 112 and a first switching element 114. The first switching element 114 is controlled by a first control signal V HD control. The first switching element 114 includes a first terminal, a second terminal, and a control terminal. The first terminal of the first switching element 114 is coupled to the output terminal 202. The second terminal of the first switching element 114 is coupled to the first terminal of the first current source 112. The control terminal of the first switching element 112 is coupled to the first control signal V HD . The control circuit 130 can directly turn on or off the discharge path of the output voltage Vout by controlling the on-state of the first switching element 114.

[0104] The operations of the readout integrated circuit 400B, the second discharge circuit 120, and the precharge circuit 500 described in the embodiments of the present invention are fully taught, suggested, and embodied in the Figure 5 embodiments shown, and thus no further description is provided herein.

[0105] Figure 9 is a schematic diagram of a sensor circuit and a readout integrated circuit according to another embodiment of the present invention. Referring to Figure 5 and Figure 9 , the readout integrated circuit 400C of this embodiment is similar to Figure 5 the readout integrated circuit 400A shown, and the main difference between the readout integrated circuit 400C and the readout integrated circuit 400A lies, for example, in the circuit structure of the first discharge circuit 110C.

[0106] Specifically, the first discharge circuit 110C includes a first current source 112, a first switching element 114, and a diode element 118. The first switching element 114 is controlled by a first control signal V HD control. The first switching element 114 includes a first terminal, a second terminal, and a control terminal. The first terminal of the first switching element 114 is coupled to a first voltage Vb1. The second terminal of the first switching element 114 is coupled to the control terminal of the first current source 112. The control terminal of the first switching element 114 is coupled to the first control signal V HD . The diode element 118 includes an anode terminal and a cathode terminal. The anode terminal of the diode element 118 is coupled to the output terminal 202, and the cathode terminal of the diode element 118 is coupled to the first terminal of the first switching element 114.

[0107] The diode element 118 can prevent the output voltage Vout from being pulled down to a specified voltage. For example, when the output voltage Vout is pulled down to the specified voltage, the diode element 118 is not turned on, thereby turning off the first current source 112 to stop the discharging operation.

[0108] The operations of the read integrated circuit 400C, the second discharge circuit 120, and the precharge circuit 500 described in the embodiments of the present invention are fully taught, suggested, and embodied in the embodiments shown in Figure 5 and thus no further description is provided herein.

[0109] Figure 10 is a flowchart of a method for operating a read integrated circuit according to an embodiment of the present invention. Referring to Figure 1 、 Figure 2 and Figure 10 , in this embodiment, the method for operating a read integrated circuit is at least applicable to the read integrated circuit 100 shown in Figure 1 and Figure 2 , but the present disclosure is not limited thereto. Taking the read integrated circuit 100 as an example, in step S100, the read integrated circuit 100 generates at least one control signal Vctrl to control the operation period of the first discharging operation. In step S110, the read integrated circuit 100 performs the first discharging operation to discharge the output terminal 202 through the first current I1 during the reading. Therefore, the voltage of the output terminal 202 of the optical sensing panel 200 can be read as a sensing signal.

[0110] The method for operating a read integrated circuit described in the embodiments of the present invention is fully taught, suggested, and embodied in the embodiments shown in Figures 1 to 9 and thus no further description is provided herein.

[0111] Figure 11 is a schematic block diagram of a read integrated circuit according to another embodiment of the present invention. Referring to Figure 11 , the read integrated circuit 600 includes a plurality of input terminals 206 for coupling to some output terminals 202 of the optical sensing panel 200. The read integrated circuit 600 further includes a first charging circuit 610 and a control circuit 130. The first charging circuit 610 is coupled to as Figure 2The input terminal 206 (or input terminals 206) shown in

[0112] Figure 12 is a schematic block diagram of a readout integrated circuit according to another embodiment of the present invention. Referring to Figure 11 and Figure 12 , the readout integrated circuit 700 of this embodiment is similar to Figure 11 the readout integrated circuit 600 shown, and the main difference between the readout integrated circuit 600 and the readout integrated circuit 700 is, for example, that the readout integrated circuit 700 further includes a second charging circuit 720. The second charging circuit 720 is coupled to the output terminal 202 of the optical sensing panel 200 (as Figure 3 shown in

[0113] ). The second charging circuit 720 is configured to charge the output terminal 202 with a second current I2 during readout. Figure 11 and Figure 12 In the embodiments of

[0114] Figure 11 and Figure 12 , at the beginning of the reading period, if the initial output voltage Vout is less than the sensing voltage Vs, the process from the initial output voltage Vout to the actual output sensing voltage Vs of the sensor circuit can be regarded as a charging process. The initial output voltage can be determined according to the pre-discharge process. Figures 1 to 10 The operation methods of the readout integrated circuit described in the embodiments of

[0115] are fully taught, suggested, and embodied in the embodiments shown in

[0116] It will be understood by those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the present disclosure. In summary, the present disclosure is intended to cover such modifications and variations provided they fall within the scope of the above claims and their equivalents.

Claims

1. A readout integrated circuit configured to read a sensing signal from an optical sensing panel, the optical sensing panel including a sensor array for fingerprint sensing, the readout integrated circuit including: A plurality of input terminals for coupling to a plurality of output terminals of the optical sensing panel; A first discharge circuit coupled to one of the plurality of input terminals and configured to discharge an output terminal included in the plurality of output terminals of the optical sensing panel through a first current during readout, wherein the readout integrated circuit reads a voltage of the output terminal of the optical sensing panel as the sensing signal, Wherein the first discharge circuit includes: A first switching element controlled to be turned on or off by a control signal, wherein a first terminal of the first switching element is coupled to the output terminal of the optical sensing panel, and a control terminal of the first switching element is coupled to the control signal; and A first current source coupled to a second terminal of the first switching element, wherein the first current source is configured to generate the first current; and A control circuit coupled to the first discharge circuit and configured to output the control signal to control a time length during an operation in which the first discharge circuit discharges the output terminal of the optical sensing panel through the first current.

2. The readout integrated circuit according to claim 1, wherein the first current source is controlled by a first voltage to generate the first current, wherein the first current source includes a first terminal, a second terminal, and a control terminal, and the first current is transmitted from the first terminal of the first current source to the second terminal of the first current source, Wherein the first terminal of the first current source is coupled to the output terminal, the second terminal of the first current source is coupled to a reference voltage, and the control terminal of the first current source is coupled to the first voltage.

3. The readout integrated circuit according to claim 1, further including: A second discharge circuit coupled to the output terminal of the optical sensing panel and configured to discharge the output terminal of the optical sensing panel through a second current during the readout.

4. The readout integrated circuit according to claim 3, wherein the second discharge circuit includes: A second current source controlled by a second voltage to generate the second current.

5. The readout integrated circuit according to claim 4, wherein the second current source includes a first terminal, a second terminal, and a control terminal, and the second current is transmitted from the first terminal to the second terminal, wherein the first terminal of the second current source is coupled to the output terminal of the optical sensing panel, the second terminal of the second current source is coupled to a reference voltage, and the control terminal of the second current source is coupled to the second voltage.

6. The readout integrated circuit according to claim 3, wherein The precharge circuit is coupled to the output terminals of the optical sensing panel and is configured to charge the output terminals of the optical sensing panel to an initial voltage during a precharge period, where the precharge period is earlier than the read period.

7. The readout integrated circuit according to claim 6, wherein the precharge circuit comprises: A third switching element, controlled by a third voltage and including a first terminal, a second terminal, and a control terminal, wherein the first terminal of the third switching element is coupled to the output terminals of the optical sensing panel, the second terminal of the third switching element is coupled to the second discharge circuit, and the control terminal of the third switching element is coupled to the third voltage.

8. The readout integrated circuit according to claim 6, wherein the second discharge circuit and the precharge circuit are provided in the readout integrated circuit.

9. The readout integrated circuit according to claim 6, wherein the second discharge circuit and the precharge circuit are provided in a display panel in which the sensor array is embedded.

10. The readout integrated circuit according to claim 3, wherein the first current is greater than or equal to the second current.

11. The readout integrated circuit according to claim 6, wherein the output terminals of the optical sensing panel are precharged to a voltage level close to the highest input voltage of the analog-to-digital converter during the precharge period.

12. A readout integrated circuit configured to read a sensing signal from an optical sensing panel, the optical sensing panel including a sensor array for fingerprint sensing, the readout integrated circuit comprising: A plurality of input terminals for coupling to a plurality of output terminals of the optical sensing panel; A first charging circuit, coupled to one of the plurality of input terminals and configured to charge an output terminal included in the plurality of output terminals of the optical sensing panel with a first current during a read period, wherein the readout integrated circuit reads a voltage of the output terminals of the optical sensing panel as the sensing signal, wherein the first charging circuit comprises: A first switching element, controlled to be turned on or off by a control signal, wherein a first terminal of the first switching element is coupled to the output terminals of the optical sensing panel, and a control terminal of the first switching element is coupled to the control signal; and A first current source, coupled to a second terminal of the first switching element, wherein the first current source is configured to generate the first current; and A control circuit, coupled to the first charging circuit and configured to output the control signal to control a time length during an operation in which the first charging circuit charges the output terminals of the optical sensing panel with the first current.

13. The readout integrated circuit according to claim 12, wherein the first current source is controlled by a first voltage to generate the first current, wherein the first current source includes a first terminal, a second terminal, and a control terminal, and the first current is transmitted from the first terminal of the first current source to the second terminal of the first current source. The first terminal of the first current source is coupled to the second terminal of the first switching element, the second terminal of the first current source is coupled to a reference voltage, and the control terminal of the first current source is coupled to the first voltage.

14. The readout integrated circuit according to claim 12, further comprising: A second charging circuit, coupled to the output terminal of the optical sensing panel and configured to charge the output terminal of the optical sensing panel with a second current during the readout.

15. The readout integrated circuit according to claim 14, wherein the second charging circuit comprises: A second current source, controlled by a second voltage to generate the second current.

16. The readout integrated circuit according to claim 15, wherein the second current source comprises a first terminal, a second terminal and a control terminal, and the second current is transmitted from the first terminal to the second terminal, wherein the first terminal of the second current source is coupled to the output terminal of the optical sensing panel, the second terminal of the second current source is coupled to a reference voltage, and the control terminal of the second current source is coupled to the second voltage.

17. The readout integrated circuit according to claim 14, wherein A pre-discharge circuit is coupled to the output terminal of the optical sensing panel and configured to discharge the output terminal of the optical sensing panel to an initial voltage during pre-discharge, wherein the pre-discharge period is earlier than the readout period.

18. The readout integrated circuit according to claim 17, wherein the pre-discharge circuit comprises: A third switching element, controlled by a third voltage and comprising a first terminal, a second terminal and a control terminal, wherein the first terminal of the third switching element is coupled to the output terminal of the optical sensing panel, the second terminal of the third switching element is coupled to the second charging circuit, and the control terminal of the third switching element is coupled to the third voltage.

19. The readout integrated circuit according to claim 17, wherein the second charging circuit and the pre-discharge circuit are provided in the readout integrated circuit.

20. The readout integrated circuit according to claim 17, wherein the second charging circuit and the pre-discharge circuit are provided in a display panel in which the sensor array is embedded.

21. The readout integrated circuit according to claim 15, wherein the first current is greater than or equal to the second current.

22. The readout integrated circuit according to claim 17, wherein the output terminal of the optical sensing panel is pre-discharged to a voltage level close to the lowest input voltage of the analog-to-digital converter during the pre-discharge.

23. A readout integrated circuit configured to read a sensing signal from an optical sensing panel, the optical sensing panel including a sensor array for fingerprint sensing, the readout integrated circuit comprising: A plurality of input terminals for coupling to a plurality of output terminals of the optical sensing panel; A first charge-discharge circuit, coupled to one of the plurality of input terminals and configured to charge or discharge an output terminal included in the plurality of output terminals of the optical sensing panel with a first current during a readout, wherein the readout integrated circuit reads a voltage of the output terminal of the optical sensing panel as the sensing signal. Wherein the first charge-discharge circuit includes: A first switching element, controlled by a first control signal; and A second switching element, controlled by a second control signal, wherein the second control signal is inverted from the first control signal; and A control circuit, coupled to the first charge-discharge circuit and configured to output the first control signal and the second control signal to control a time length during an operation of the first charge-discharge circuit to charge or discharge the output terminal of the optical sensing panel with the first current.

24. The readout integrated circuit according to claim 23, wherein A first terminal of the first switching element is coupled to a first voltage, a second terminal of the first switching element is coupled to a control terminal of the first current source, and a control terminal of the first switching element is coupled to the first control signal; and A first terminal of the second switching element is coupled to the control terminal of the first current source, a second terminal of the second switching element is coupled to a reference voltage, and a control terminal of the second switching element is coupled to the second control signal.

25. A readout integrated circuit configured to read a sensing signal from an optical sensing panel, the optical sensing panel including a sensor array for fingerprint sensing, the readout integrated circuit including: A plurality of input terminals for coupling to a plurality of output terminals of the optical sensing panel; A first charge-discharge circuit, coupled to one of the plurality of input terminals and configured to charge or discharge an output terminal included in the plurality of output terminals of the optical sensing panel with a first current during a readout, wherein the readout integrated circuit reads a voltage of the output terminal of the optical sensing panel as the sensing signal. Wherein the first charge-discharge circuit includes: A first current source; A first switching element, controlled by a control signal, wherein a first terminal of the first switching element is coupled to a first voltage, a second terminal of the first switching element is coupled to a control terminal of the first current source, and a control terminal of the first switching element is coupled to the control signal; and A diode element, including an anode terminal and a cathode terminal, wherein the anode terminal of the diode element is coupled to the output terminal of the optical sensing panel, and the cathode terminal of the diode element is coupled to the first terminal of the first switching element; and A control circuit, coupled to the first charge-discharge circuit and configured to output the control signal to control a time length during an operation of the first charge-discharge circuit to charge or discharge the output terminal of the optical sensing panel with a first current.

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