CN108124484B

CN108124484B - Light sensing method of light sensing device

Info

Publication number: CN108124484B
Application number: CN201780002291.XA
Authority: CN
Inventors: 李问杰
Original assignee: Liuzhou Zibo Technology Co ltd
Current assignee: Liuzhou Zibo Technology Co ltd
Priority date: 2017-12-30
Filing date: 2017-12-30
Publication date: 2023-04-18
Anticipated expiration: 2037-12-30
Also published as: WO2019127577A1; CN108124484A

Abstract

The invention discloses a light sensing method of a light sensing device, wherein the light sensing device comprises a plurality of light sensing pixels, and a first scanning driving signal and a second scanning driving signal are provided for all the light sensing pixels, so that the light sensing is started to be executed by all the light sensing pixels when first preset time is reached, and the light sensing is finished when third preset time is reached, so that electric signals generated when the light sensing is executed by the light sensing pixels are latched; and after all the photosensitive pixels finish performing the light sensing, sequentially providing an output control signal to the plurality of photosensitive pixels so as to control the latch electric signals corresponding to the plurality of photosensitive pixels to be output.

Description

Light sensing method of light sensing device

Technical Field

The present invention relates to a light sensing method for a light sensing device for sensing biometric information.

Background

At present, fingerprint identification has gradually become a standard component of electronic products such as mobile terminals. Since optical fingerprint recognition has a stronger penetration ability than capacitive fingerprint recognition, the application of optical fingerprint recognition to mobile terminals is a future development trend. However, the existing optical fingerprint recognition structure applied to the mobile terminal still needs to be improved.

Disclosure of Invention

The embodiment of the invention aims to solve at least one technical problem in the prior art. Therefore, the embodiment of the invention needs to provide a photosensitive device, a photosensitive method thereof and an electronic device.

The light sensing method of the light sensing device of the embodiment of the invention, the light sensing device comprises a plurality of light sensing pixels, and is characterized in that: the light sensing method comprises the following steps:

providing a first scanning driving signal and a second scanning driving signal to all photosensitive pixels so that all the photosensitive pixels start to perform light sensing when first preset time is reached and finish performing the light sensing when third preset time is reached so as to latch electric signals generated when the photosensitive pixels perform the light sensing;

and after all the photosensitive pixels finish performing the light sensing, sequentially providing an output control signal to the plurality of photosensitive pixels so as to control the latch electric signals corresponding to the plurality of photosensitive pixels to be output.

The photosensitive driving circuit drives all photosensitive pixels of the photosensitive device to simultaneously perform light sensing, controls all photosensitive speed limits to finish performing the light sensing, and latches electric signals generated when the photosensitive pixels perform the light sensing, so that enough time and flexibility are provided for the output control of photosensitive signals. In addition, the control time sequence of the photosensitive pixels in the photosensitive device is simple, and the photosensitive time is short, so that the sensing speed is improved. In addition, all the photosensitive pixels simultaneously execute light sensing, so that the influence of object movement on the light sensing is avoided, the image distortion resistance is high, and the sensing precision is improved.

In some embodiments, the plurality of light-sensitive pixels are distributed in an array; the step of sequentially providing the output control signals to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing specifically includes:

and after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of photosensitive pixels line by line or in an interlaced mode until the latching electric signals corresponding to all the photosensitive pixels are all output. The output control signal is provided to the second scanning line by line or interlaced line by line, so that the output of the photosensitive signal of the whole line is realized, and the sensing speed is further improved.

In some embodiments, the plurality of photosensitive pixels are distributed in an array; the step of sequentially providing the output control signals to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing specifically includes:

after all photosensitive pixels finish executing the light sensing, according to the distribution sequence of the photosensitive pixels, the output control signals are provided to the photosensitive pixels line by line from head to tail, and then the output control signals are provided to the photosensitive pixels line by line from tail to head, so that the electric signals output twice are accumulated to obtain the final electric signal.

According to the embodiment of the invention, the photosensitive signals can be read twice by outputting the photosensitive signals twice, so that the reading waiting time of different photosensitive pixels is balanced, the influence of charge leakage on photosensitive signal acquisition is further solved, and the sensing precision is improved.

In some embodiments, the step of sequentially providing the output control signal to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing specifically includes:

and after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of photosensitive pixels point by point according to the distribution sequence of the plurality of photosensitive pixels. Therefore, the electric signals latched by the photosensitive pixels are output point by point, so that only one signal reading channel is arranged, and the cost of the photosensitive device is saved.

In some embodiments, the photosensitive pixel includes a photosensitive unit and a switch unit electrically connected to the photosensitive unit, the photosensitive unit includes at least a photosensitive device and a first capacitor, and the switch unit includes a first switch and a third switch; the step of providing the first scan driving signal and the second scan driving signal to all the photosensitive pixels further includes:

providing the first scanning driving signal to the first switches in all the photosensitive pixels, and simultaneously providing the second scanning driving signal to the third switches in all the photosensitive pixels so as to control the first switches and the third switches in all the photosensitive pixels to be closed, and when a first preset time is reached, controlling the first switches to be opened, and starting the photosensitive unit to perform photosensitive sensing; and when the third preset time is reached, controlling the third switch to be switched off, and finishing the light sensing by the light sensing unit.

In some embodiments, the light-sensitive pixel further comprises a signal output unit electrically connected to the light-sensitive unit, the signal output unit comprising a second switch; the step of sequentially providing an output control signal to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing further includes:

and after the third switch of the switch unit is switched off, the output control signals are sequentially provided for the second switch so as to control the second switch of the signal output unit to be switched on and output electric signals generated when the photosensitive units in the photosensitive pixels execute light sensing.

In some embodiments, the photosensitive pixel includes a photosensitive unit and a switch unit electrically connected to the photosensitive unit; the photosensitive unit comprises at least one photosensitive device, a first capacitor and a second capacitor, and the switch unit comprises a fourth switch, a fifth switch and a seventh switch; the step of providing the first scan driving signal and the second scan driving signal to all the photosensitive pixels further includes:

providing the first scanning driving signal to the fourth switches and the fifth switches in all the photosensitive pixels, and simultaneously providing the second scanning driving signal to the seventh switches in all the photosensitive pixels so as to control the fourth switches, the fifth switches and the seventh switches in all the photosensitive pixels to be switched on and off, and when first preset time is reached, controlling the fourth switches and the fifth switches to be switched off, and starting the photosensitive unit to perform photosensitive sensing; and when the third preset time is reached, the seventh switch is controlled to be switched off, the photosensitive unit finishes executing the light sensing, and the first capacitor latches the electric signal generated when the photosensitive unit executes the light sensing.

In some embodiments, the photosensitive pixel further comprises a signal output unit electrically connected to the photosensitive unit, the signal output unit comprising a sixth switch and a conversion circuit; the step of sequentially controlling the plurality of photosensitive pixels to output the electric signals generated when the plurality of photosensitive pixels perform the light sensing after all the photosensitive pixels finish performing the light sensing further comprises:

after the seventh switch of the switch unit is switched off, the output control signals are sequentially provided for the sixth switch to control the sixth switch of the signal output unit to be switched on, so that the conversion circuit receives a constant electric signal, and the constant electric signal is converted into two different electric signals according to the electric signal latched by the photosensitive unit and is output.

In some embodiments, the third predetermined time is dynamically adjusted based on the intensity of the received optical signal.

In some embodiments, the greater the intensity of the received optical signal, the shorter the third predetermined time; the smaller the intensity of the received optical signal, the longer the third predetermined time.

The embodiment of the invention adjusts the reading time of the electric signals generated by the photosensitive pixels in time according to the intensity of the optical signals, ensures the accurate reading of the electric signals and improves the sensing precision.

In some embodiments, the constant electrical signal is a constant current signal.

In some embodiments, the light sensing method further comprises:

and acquiring preset biological characteristic information of an object contacting or approaching the photosensitive device according to the read electric signals generated when the plurality of photosensitive pixels perform light sensing.

Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of embodiments of the invention.

Drawings

The above and/or additional aspects and advantages of embodiments of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram illustrating an array distribution of photosensitive pixels in a photosensitive device according to an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of one embodiment of the photosensitive pixel of FIG. 1;

FIG. 3 is a timing diagram of signals at nodes of the photosensitive pixel of FIG. 2 when performing light sensing;

FIG. 4 is a diagram illustrating the connection between a photosensitive pixel and a scan line, a data line, and a signal reference line in the photosensitive device according to an embodiment of the present invention, wherein the photosensitive pixel is the photosensitive pixel shown in FIG. 2;

FIG. 5 is a block diagram of an embodiment of the photosensitive driving unit shown in FIG. 4;

FIG. 6 is a timing diagram of signals of the embodiment of the photosensitive device shown in FIG. 4 performing photo sensing;

FIG. 7 is a timing diagram illustrating signals of another embodiment of the light sensing apparatus shown in FIG. 4;

FIG. 8 is a schematic circuit diagram of another embodiment of the light-sensing pixel of FIG. 1;

FIG. 9 is a timing diagram illustrating signals at nodes of the photosensitive pixel of FIG. 8 when performing light sensing;

FIG. 10 is a schematic diagram of a circuit configuration of yet another embodiment of the light-sensing pixel shown in FIG. 1;

FIG. 11 is a diagram illustrating a connection structure between a photosensitive pixel and a scan line, a data line and a signal reference line in the photosensitive device according to an embodiment of the present invention, wherein the photosensitive pixel is the photosensitive pixel structure shown in FIG. 8;

FIG. 12 is a block diagram of an embodiment of the photosensitive driving unit shown in FIG. 11;

FIG. 13 is a schematic view of a structure of a photosensitive panel in the photosensitive device according to an embodiment of the present invention;

FIG. 14 is a flowchart illustrating a photo sensing method of a photo sensing device according to an embodiment of the present invention;

FIG. 15 is a schematic structural diagram of an electronic device to which a photosensitive device according to an embodiment of the present invention is applied;

FIG. 16 is a schematic cross-sectional view of one embodiment of the electronic device shown in FIG. 15 along line I-I, with FIG. 16 showing a partial structure of the electronic device;

FIG. 17 is a schematic diagram illustrating a position of a display region of a display panel and a position of a sensing region of a photosensitive panel according to an embodiment of the present invention;

fig. 18 is a schematic sectional view of another embodiment of the electronic device shown in fig. 15 taken along line I-I, and fig. 18 shows a partial structure of the electronic device.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. "contact" or "touch" includes direct contact or indirect contact.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, certain example components and settings are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.

Further, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other structures, components, and so forth. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring the invention.

The embodiment of the invention provides a photosensitive device arranged in electronic equipment, and particularly provides a photosensitive device arranged below a display screen of the electronic equipment. Such as, but not limited to, OLED display panels and the like, have display devices that emit light signals. When the electronic equipment works, the display screen sends out optical signals to execute corresponding image display. At this time, if a target object contacts or touches the electronic device, the optical signal emitted by the display screen is reflected after reaching the target object, the reflected optical signal passes through the display screen and is received by the photosensitive device, and the photosensitive device converts the received optical signal into an electrical signal corresponding to the optical signal, so as to form the predetermined biological characteristic information of the target object according to the electrical signal generated by the photosensitive device.

The biometric information of the target object includes, but is not limited to, skin texture information such as fingerprints, palm prints, ear prints, and soles of feet, and other biometric information such as heart rate, blood oxygen concentration, and veins. The target object is, for example, but not limited to, a human body, and may be other suitable types of objects.

In some embodiments, the electronic device may also be provided with a light source for biometric information sensing. When the electronic device performs the sensing of the biometric information, the light source emits a corresponding light signal, such as infrared light, so as to sense the heart rate, blood oxygen concentration, vein and other information of the target object.

Examples of the electronic devices include, but are not limited to, consumer electronics, home electronics, vehicle-mounted electronics, financial terminal products, and other suitable types of electronic products. The consumer electronic products include mobile phones, tablet computers, notebook computers, desktop displays, all-in-one computers, and the like. The household electronic products are intelligent door locks, televisions, refrigerators, wearable equipment and the like. The vehicle-mounted electronic products are vehicle-mounted navigators, vehicle-mounted DVDs and the like. The financial terminal products are ATM machines, terminals for self-service business handling and the like.

Referring to fig. 1, fig. 1 shows an array structure of photosensitive pixels in a photosensitive device, where the photosensitive device 20 includes a plurality of photosensitive pixels 22, and the photosensitive pixels 22 are arranged in rows and columns to form a photosensitive array 201. Specifically, the photosensitive array 201 includes a plurality of rows of photosensitive pixels and a plurality of columns of photosensitive pixels, each row of photosensitive pixels being spaced apart along the X-direction, and each column of photosensitive pixels being spaced apart along the Y-direction. When the photosensitive device 20 performs image sensing, each row of photosensitive pixels 22 may be driven line by line in the X direction to perform light sensing, and then an electrical signal generated by each photosensitive pixel 22 performing light sensing may be read in the Y direction. Of course, the photosensitive pixels 22 forming the photosensitive array 201 are not limited to the vertical relationship shown in fig. 1, and may be distributed in other regular or irregular manners.

In some embodiments, each light-sensitive pixel 22 includes a sensing unit and a signal output unit. The sensing unit is used for receiving a light sensing control signal, executing light sensing when receiving the light sensing control signal, and generating a corresponding light sensing signal; the signal output unit is used for receiving an output control signal and outputting a photosensitive signal generated when the sensing unit executes photosensitive sensing when receiving the output control signal.

In particular, referring to fig. 2, fig. 2 illustrates a circuit configuration of one of the light-sensitive pixels 22 of fig. 1. In the embodiment of the invention, a photosensitive pixel 22 has a first input terminal In1, a second input terminal In2, a third input terminal In3, a fourth input terminal In4, and a first output terminal Out1. The light sensing control signal includes a first scan driving signal and a second scan driving signal. The light-sensing pixel 22 includes a sensing unit including a switching unit 221 and a light-sensing unit 222, and a signal output unit 223, and the light-sensing unit 222 is connected between the switching unit 221 and the signal output unit 223. The switch unit 221 receives a reference signal Vref through the third input terminal In3, and In addition, the switch unit 221 also receives a first scanning driving signal through the first input terminal In1, and receives a second scanning driving signal through the fourth input terminal In4, and transmits the reference signal Vref to the photosensitive unit 222 when receiving the first scanning driving signal and the second scanning driving signal, so as to drive the photosensitive unit 222 to perform optical sensing, and ends optical sensing after the photosensitive unit 222 starts to perform optical sensing and continues for a predetermined time, and latches a photosensitive signal generated by the photosensitive unit 222 performing optical sensing. The light sensing unit 222 receives the light signal and converts the received light signal into a corresponding electrical signal upon receiving the light signal. The signal output unit 223 receives the output control signal through the second input terminal In2, and outputs the electrical signal generated by the light sensing unit 222 from the first output terminal Out1 according to the output control signal.

Optionally, the first scan driving signal, the second scan driving signal and the output control signal are all pulse signals, and the duration of the high level signal in the first scan driving signal is a first predetermined time, the duration of the high level signal in the output control signal is a second predetermined time, the duration of the high level signal in the second scan driving signal is a third predetermined time, and the third predetermined time is greater than the first predetermined time.

In some embodiments, the light sensing unit 222 includes a light sensing device, which includes a first electrode and a second electrode, the first electrode is used for receiving the reference signal Vref transmitted by the switch unit 221, and the second electrode is used for receiving a fixed electrical signal. A driving voltage for driving the photosensitive device is formed by applying a reference signal Vref and a fixed electric signal to both electrodes of the photosensitive device. Such as but not limited to a photodiode D1, and may alternatively be a photo-resistor, a photo-transistor, a thin film transistor, etc. It should be noted that the number of the photosensitive devices may also be 2, 3, and so on. Taking the photodiode D1 as an example, the photodiode D1 includes an anode and a cathode, wherein the anode receives a fixed electrical signal, such as the ground signal NGND; the negative electrode is used as a first electrode of the light sensing device and is used for receiving the reference signal Vref transmitted by the switch unit 221. It should be noted that, when the reference signal Vref and the fixed electrical signal are applied to the two ends of the photodiode D1 correspondingly, a reverse voltage is formed across the two ends of the photodiode D1, so as to drive the photodiode to perform the light sensing.

When the switch unit 221 is closed, the reference signal Vref is transmitted to the cathode of the photodiode D1 through the closed switch unit 221, and since the photodiode D1 has an equivalent capacitance inside, the reference signal Verf charges the equivalent capacitance inside the photodiode D1, so that the voltage Vg on the cathode of the photodiode D1 gradually rises and reaches the voltage value of the reference signal Vref and remains unchanged when the first predetermined time is reached. At this time, the voltage difference across the photodiode D1 will reach the reverse voltage for driving the photodiode to operate, i.e. the photodiode D1 is in an operating state. When the first scan driving signal is changed from the high level to the low level when the first predetermined time is reached, the switch unit 221 is turned off, and a discharge loop is formed inside the photodiode D1. At this time, if an optical signal is irradiated to the photodiode D1, the reverse current of the photodiode D1 increases rapidly, and the voltage Vg at the negative electrode node of the photodiode D1 changes, i.e., gradually decreases with the discharge time. Since the intensity of the optical signal is larger, the reverse current generated by the photodiode D1 is also larger, and the falling speed of the voltage Vg at the negative electrode node of the photodiode D1 is faster.

Further, the light sensing unit 222 further includes a first capacitor c1. The first capacitor c1 is used for forming a discharge loop with the photosensitive device to obtain a corresponding photosensitive signal when performing photosensitive sensing. Specifically, as shown in fig. 2, the first capacitor c1 is disposed in parallel with the photosensitive device, i.e., a first plate of the first capacitor c1 is connected to the negative electrode of the photodiode D1, and a second plate of the first capacitor c1 is grounded. When the reference signal Vref is transmitted to the cathode of the photodiode D1, the first capacitor c1 is also charged, and when the switch unit 221 is turned off, the first capacitor c1 and the photodiode D1 form a discharge loop, and the voltage of the first plate of the first capacitor c1 (i.e., the voltage Vg) also gradually decreases with the discharge time. By arranging the first capacitor c1, the capacitance capacity of the photosensitive unit 222 is increased, so that the voltage drop speed on the cathode of the photodiode D1 is reduced, an effective photosensitive signal can be ensured to be acquired, and the sensing precision of the photosensitive device 20 on a target object is improved.

Further, the first capacitor c1 is a variable capacitor, for example, a capacitor array formed by a plurality of capacitors, and the plurality of capacitors are arranged in parallel, and the capacity change of the first capacitor c1 is realized by controlling whether the plurality of capacitors are connected or not. Because the first capacitor c1 is set as a variable capacitor, the capacity adjustment of the first capacitor c1 adapts to the change of the received optical signal, thereby obtaining an accurate and effective photosensitive signal. Specifically, the capacitance of the first capacitor c1 is larger as the intensity of the received optical signal is larger, and the capacitance of the first capacitor c1 is smaller as the intensity of the received optical signal is smaller.

In some embodiments, the switch unit 221 includes a first transistor T1 and a fourth transistor T4, and the first transistor T1 and the fourth transistor T4 are any one or more of, for example, but not limited to, a triode, a MOS transistor, and a thin film transistor. Taking a MOS transistor as an example, the first transistor T1 includes a first control electrode C1, a first transmission electrode S1 and a second transmission electrode S2, wherein the first control electrode is a gate of the MOS transistor, the first transmission electrode S1 is a drain of the MOS transistor, and the second transmission electrode S2 is a source of the MOS transistor. The fourth transistor T4 includes a fourth control electrode C4, a seventh transmission electrode S7 and an eighth transmission electrode S8, where the fourth control electrode C4 is a gate of the MOS transistor, the seventh transmission electrode S7 is a drain of the MOS transistor, and the eighth transmission electrode S8 is a source of the MOS transistor.

Further, the first control electrode C1 is connected to the first input terminal In1, and is configured to receive a first scan driving signal; the first transfer electrode S1 is connected to the third input terminal In3 for receiving a reference signal Vref; the second transfer electrode S2 is connected to the cathode of the photodiode D1 in the light sensing unit 222. When a first scan driving signal is input through the first input terminal In1, the first transistor T1 is turned on according to the first scan driving signal, and the reference signal Vref is transmitted to the cathode of the photodiode D1 through the first transmission electrode S1 and the second transmission electrode S2. The fourth control electrode C4 is connected to the fourth input end In4, and is configured to receive the second scan driving signal; the seventh transfer electrode S7 is connected to a first electrode (e.g., a cathode of a photodiode) of the light sensing device, and the eighth transfer electrode S8 is connected to a first plate of the first capacitor c1. And the first plate of the first capacitor C1 is used for connecting the signal output unit 223', i.e. the first plate of the first capacitor C1 is connected with the third control electrode C3 of the third transistor T3. When the second scan driving signal is input through the fourth input terminal In4, the fourth transistor T4 is turned on according to the second scan driving signal, and the reference signal Vref is transmitted to the first plate of the first capacitor c1 through the first transistor T1 and the fourth transistor T4. Since the first scan driving signal is converted into a low level signal when the first predetermined time is reached, the first transistor T1 is turned off, and at this time, the first capacitor c1 and the photodiode D1 form a discharge loop to start performing the photo sensing.

In some embodiments, the signal output unit 223 includes a second transistor T2 and a buffer circuit. The buffer circuit is used for buffering the electrical signal generated by the light sensing unit 222. The second transistor T2 is, for example, but not limited to, any one or more of a triode, a MOS transistor, and a thin film transistor. Taking a MOS transistor as an example, the second transistor T2 includes a second control electrode C2, a third transmission electrode S3 and a fourth transmission electrode S4, where the second control electrode C2 is a gate of the MOS transistor, the third transmission electrode S3 is a drain of the MOS transistor, and the fourth transmission electrode S4 is a source of the MOS transistor. The second control electrode C2 is connected to the second input terminal In2, and is configured to receive an output control signal; the third transmission electrode S3 is connected with the buffer circuit and used for receiving the electric signal output by the buffer circuit; and the fourth transmission electrode S4 is connected to the first output terminal Out1, and is configured to output the electrical signal buffered by the buffer circuit.

Further, the buffer circuit is connected between the light sensing unit 222 and the second transistor T2, and is configured to buffer the electrical signal converted by the light sensing unit 222, and output the buffered electrical signal when the second transistor T2 is turned on. In this embodiment, the buffer circuit includes a third transistor T3, and the third transistor T3 is, for example, but not limited to, any one or more of a triode, a MOS transistor, and a thin film transistor. Taking a MOS transistor as an example, the third transistor T3 includes a third control electrode C3, a fifth transfer electrode S5, and a sixth transfer electrode S6, where the third control electrode C3 is a gate of the MOS transistor, the fifth transfer electrode S5 is a drain of the MOS transistor, and the sixth transfer electrode S6 is a source of the MOS transistor. The third control electrode C3 is connected to the cathode of the photodiode D1, and is configured to receive an electrical signal generated when the photodiode D1 performs light sensing; the fifth transmission electrode S5 is used for receiving a voltage signal Vcc; the sixth transfer electrode S6 is connected to the third transfer electrode S3 of the second transistor T2 for outputting a buffered electrical signal when the second transistor T2 is turned on.

In the third transistor T3, the voltage Vs of the sixth transfer electrode S6 changes with the voltage Vg of the third control electrode C3, i.e., the voltage of the sixth transfer electrode S6 is not affected no matter how the circuit load connected to the sixth transfer electrode S6 changes. Also, due to the characteristics of the third transistor T3, the voltage Vs is always lower than the voltage Vg by a threshold voltage, which is the threshold voltage of the third transistor T3. Therefore, the buffer circuit plays a role of buffer isolation, and isolates the electrical signal generated when the photosensitive unit 222 performs light sensing, so as to prevent other circuit loads from affecting the photosensitive signal generated by the photosensitive unit 222, thereby ensuring that the photosensitive pixels 22 accurately perform light sensing, and improving the sensing precision of the photosensitive device 20 on the target object.

Referring to fig. 3, fig. 3 shows the signal timing sequence at each node when the photosensitive pixel 22 shown in fig. 2 performs photosensitive sensing, where Vg is the voltage at the cathode of the photodiode D1 and is also the voltage at the third control electrode C3 of the third transistor T3; vs is a voltage on the sixth transfer electrode S6 of the third transistor T3.

At time t1, a first scan driving signal is input through the first input terminal In1, and a second scan driving signal is input through the fourth input terminal In 4. The first transistor T1 is turned on for a first predetermined time (i.e., T2-T1) according to the first scan driving signal, and the reference signal Vref is applied to the cathode of the photodiode D1 through the first and second transfer electrodes S1 and S2 during the first predetermined time. Since the photodiode D1 has an equivalent capacitance therein, the reference signal Verf charges the equivalent capacitance in the photodiode D1, so that the voltage at the cathode of the photodiode D1 gradually rises and remains unchanged after reaching the voltage value of the reference signal Vref. According to the second scan driving signal, the fourth transistor T4 is turned on for a third predetermined time Δ T2 (i.e., T3-T1), the reference signal Vref is applied to the first plate of the first capacitor c1 through the first transistor T1 and the fourth transistor T4, so as to charge the first capacitor c1, and the voltage on the first plate of the first capacitor c1 gradually rises and remains unchanged after reaching the voltage value of the reference signal Vref.

At time t2, the first scan driving signal changes from high level to low level, and the second scan driving signal remains at high level. At this time, the first input terminal In1 becomes a low level signal, the first transistor T1 is turned off, the first capacitor c1 and the photodiode D1 form a discharge loop, that is, the first capacitor c1 discharges the photodiode D1, and the voltage Vg on the first plate of the first capacitor c1 gradually decreases. If no optical signal is irradiated on the photodiode D1, the current inside the photodiode D1 is very weak, so that the voltage Vg on the first plate of the first capacitor c1 remains substantially unchanged; when the photodiode D1 is irradiated with the optical signal, a current signal proportional to the optical signal is generated inside the photodiode D1, and the stronger the optical signal is, the larger the current generated by the photodiode D1 is, so that the falling speed of the voltage Vg on the first plate of the first capacitor c1 is faster. Due to the characteristics of the third transistor, the voltage Vs on the sixth transfer electrode S6 of the third transistor T3 varies with the voltage Vg on the first plate of the first capacitor c1, and the voltage Vs is always lower than the voltage Vg by Vth, which is the threshold voltage of the third transistor T3.

At time t3, the second scan driving signal changes from high level to low level. At this time, the fourth input terminal In4 becomes a low level signal, the fourth transistor T4 is turned off, the first capacitor c1 cannot form a discharge loop, and the voltage Vg on the first plate of the first capacitor c1 remains unchanged, so that the photo-sensing signal generated when the photo-sensing unit 222 performs photo-sensing is latched.

At time t4, an output control signal is input through the third input terminal In3, the output control signal is a pulse signal, and the duration of the high level In the pulse signal is a second predetermined time. According to the output control signal, the second transistor T2 is turned on, and at this time, the voltage Vg on the first plate of the first capacitor c1 is output from the first output terminal Out1 through the sixth transmission electrode S6 of the third transistor T3, the third transmission electrode S3 of the second transistor T2, and the fourth transmission electrode S4. The voltage output by the first output terminal Out1 gradually rises from the low level to the voltage Vs on the sixth transmission electrode S6, and then changes following the change of the voltage Vs on the sixth transmission electrode S6. Since the first capacitor c1 latches the voltage Vg beginning at time t3, the voltage Vs on the sixth transmission electrode S6 will remain unchanged, and therefore the voltage output by the first output terminal Out1 will remain at the magnitude of the voltage Vs.

At time T5, the output control signal changes from high level to low level, the third input terminal In3 changes to a low level signal, the second transistor T2 is turned off, and the voltage output by the first output terminal Out1 gradually drops or remains unchanged. In order to ensure the effective output of the next signal, the output voltage of the first output terminal Out1 needs to gradually drop to a low level. Since the voltage output by the first output terminal Out1 reflects the electrical signal converted by the photodiode D1, the magnitude of the electrical signal changed by the photodiode D1 due to the reception of the optical signal can be obtained by reading the voltage signal of the first output terminal Out1, and the biometric information of the target object is generated.

In the embodiment of the present invention, the switch unit 221 is not only used to drive the light sensing unit 222 to perform light sensing, but also used to control the light sensing unit 222 to finish performing light sensing, and latch the electrical signals generated when the light sensing unit 222 performs light sensing, so that the light sensing pixels in different rows can perform light sensing simultaneously, and even all the light sensing pixels perform light sensing simultaneously, thereby providing sufficient time and flexibility for output control of light sensing signals.

Further, the third predetermined time Δ t2 may be a fixed value or a variable value. Since the larger the light signal received by the photodiode D1, the faster the falling speed of the voltage Vg and thus the voltage Vs, the magnitude of Δ t2 is adjusted according to the intensity of the received light signal in order to achieve accurate and effective acquisition of the light sensing signal. Specifically, the greater the intensity of the optical signal, the shorter the third predetermined time Δ t 2; the smaller the intensity of the optical signal is, the longer the third predetermined time Δ t2 is increased.

In some embodiments, referring to fig. 4, fig. 4 illustrates a connection structure of the photosensitive pixels 22 in the photosensitive device 20 with the respective scan lines, data lines, and signal reference lines, and the photosensitive pixels are in the circuit structure illustrated in fig. 2. The photosensitive device 20 further includes a scan line group, a data line group, and a signal reference line group electrically connected to the plurality of photosensitive pixels 22. The scanning line group comprises a first scanning line group consisting of a plurality of first scanning lines, a second scanning line group consisting of a plurality of second scanning lines and a third scanning line group consisting of a plurality of third scanning lines, the data line group comprises a plurality of data lines, and the signal reference line group comprises a plurality of signal reference lines. Taking the photosensitive array 201 in fig. 1 as an example, in the photosensitive array 201, a row of photosensitive pixels in the X direction includes n photosensitive pixels 22 arranged at intervals, and a column of photosensitive pixels in the y direction includes m photosensitive pixels 22 arranged at intervals, so that the photosensitive array 201 includes m × n photosensitive pixels 22 in total. Correspondingly, the first scanning line group comprises m first scanning lines which are arranged at intervals along the Y direction, such as G11, G12, … G1m; the second scanning line group comprises m second scanning lines, and the m second scanning lines are also arranged at intervals along the Y direction, such as G21, G22, … G2m; the third scanning line group comprises m third scanning lines which are also arranged at intervals along the Y direction, such as G31, G32, … G3m; the signal reference line group comprises m signal reference lines which are arranged at intervals along the Y direction, such as L1, L2, … Lm; the data line group comprises n data lines, and the n data lines are arranged at intervals along the X direction, such as Sn1, sn2, … Sn-1, sn. Of course, the scan line group, the data line group and the signal reference line group of the light sensing device 20 may be distributed in other regular or irregular manners. In addition, since the first scanning line, the second scanning line, the third scanning line, the signal reference line and the data line have conductivity, the first scanning line, the second scanning line, the third scanning line, the signal reference line and the data line at the crossing position are isolated by an insulating material.

Specifically, the first scan line is connected to the first input terminal In1 of the photosensitive pixel 22, the second scan line is connected to the second input terminal In2 of the photosensitive pixel 22, the signal reference line is connected to the third input terminal In3 of the photosensitive pixel 22, the third scan line is connected to the fourth input terminal In4 of the photosensitive pixel 22, and the data line is connected to the first output terminal Out1 of the photosensitive pixel 22. For convenience of wiring, the first scanning line, the second scanning line, the third scanning line and the signal reference line are all led out from the X direction, and the data line is led out from the Y direction.

In some embodiments, the photosensitive device 20 further includes a photosensitive driving circuit for driving the plurality of photosensitive pixels to perform the photosensitive sensing, and the photosensitive driving circuit is configured to: driving all photosensitive pixels to simultaneously execute light sensing, and controlling all the photosensitive pixels to finish the light sensing after the photosensitive pixels start to execute the light sensing so as to latch electric signals generated when the photosensitive pixels execute the light sensing; and after all the photosensitive pixels finish executing the light sensing, sequentially controlling the latching electric signals corresponding to the plurality of photosensitive pixels to be output. All the photosensitive pixels can simultaneously carry out light sensing through the light sensing driving circuit, electric signals generated when the photosensitive pixels carry out light sensing are latched, and then the latched electric signals corresponding to the photosensitive pixels are sequentially controlled to be output. Therefore, the control time sequence of the photosensitive pixels is simple, the photosensitive time is short, and the sensing speed is improved. In addition, all the photosensitive pixels simultaneously execute light sensing, so that the influence of object movement on the light sensing is avoided, the image distortion resistance is high, and the sensing precision is improved.

Further, with reference to fig. 4, the photo-sensing driving circuit includes a photo-sensing driving unit 24, and the first scan line, the second scan line, the third scan line, and the signal reference line are all connected to the photo-sensing driving unit 24. Specifically, referring to fig. 5, fig. 5 shows a structure of an embodiment of the photosensitive driving unit 24 in fig. 4. The photosensitive driving unit 24 includes a first driving circuit 241 providing a first scan driving signal, a second driving circuit 242 providing an output control signal, a reference circuit 243 providing a reference signal Vref, and a third driving circuit 244 providing a second scan driving signal. The circuits of the photosensitive driving unit 24 can be integrated into a control chip through silicon process, but the circuits of the photosensitive driving unit 24 can also be formed separately. For example, the first and

second driving circuits

241, 242 and the third driving circuit 244 are formed on the same substrate together with the photosensitive pixels 22, and the reference circuit 243 is connected to a plurality of signal reference lines on the photosensitive device 20 through a flexible circuit board.

In some embodiments, the reference circuit 243 is used for providing the reference signal Vref, and the reference circuit 243 is selectively electrically connected to the light sensing unit 222 through a first switch (e.g., the first transistor T1 in the switch unit 221 shown in fig. 2). When the first switch is closed, the reference signal Vref is transmitted to the corresponding light sensing unit 222 through the closed first switch.

The first driving circuit 241 is electrically connected to the first scan line of the photosensitive device 20, and configured to provide a first scan driving signal to the first switches of all the photosensitive pixels 22 to control the first switches to be turned on, and when a first predetermined time (e.g., t2-t1 shown in fig. 3) is reached, control the first switches to be turned off, so as to drive the photosensitive units 222 in all the photosensitive pixels 22 to start performing the light sensing.

The third driving circuit 244 is electrically connected to the third scan line of the photosensitive device 20, and configured to provide a second scan driving signal to the third switches (e.g., the fourth transistors T4 in the switch unit 221 shown in fig. 3) in all the photosensitive pixels 22 while the first driving circuit 241 provides the first scan driving signal, so that the third switches are closed while the first switches are closed, and when the third switches are closed and reach a third predetermined time (e.g., T3-T1 shown in fig. 3), the third switches are controlled to be opened, so as to control the photosensitive units 222 in all the photosensitive pixels to end performing the photosensitive sensing, and an electrical signal generated when the photosensitive units 222 perform the photosensitive sensing is latched by the first capacitor c1.

The second driving circuit 242 is electrically connected to the second scan line of the light sensing device 20, and configured to sequentially provide an output control signal to the second switches (e.g., the second transistors T2 in the signal output unit 223 shown in fig. 3) of the plurality of light sensing pixels after controlling the light sensing units 222 to finish performing light sensing, for example, when the third switch is turned off and reaches a fifth predetermined time (e.g., time T4 shown in fig. 3), and control the second switches to be turned on and continue for a second predetermined time, so as to sequentially output the latched electrical signals corresponding to the light sensing units 222 of the plurality of light sensing pixels.

Further, in some embodiments, the second driving circuit 242 is configured to: and after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of second scanning lines line by line or in an interlaced manner until the latching electric signals corresponding to all the photosensitive pixels are all output. The output control signal is provided to the second scanning line by line or interlaced line by line, so that the output of the photosensitive signal of the whole line is realized, and the sensing speed is further improved.

Referring to fig. 6, fig. 6 illustrates a timing when the light sensing device shown in fig. 4 performs light sensing in such a manner that light sensing is performed while light sensing outputs light sensing signals line by line. In particular, t ₁ At the moment, providing a first scanning driving signal and a second scanning driving signal to all photosensitive pixels of all rows to control all photosensitive pixels to perform light sensing, and at t ₂ And controlling all the photosensitive pixels to finish executing the light sensing at all times, and latching the electric signals generated when the photosensitive pixels execute the light sensing. t is t ₁₁ At the moment, providing an output control signal for the photosensitive pixel of the 1 st row to drive the latch electric signal output corresponding to the photosensitive pixel of the 1 st row, t ₁₂ At time, providing output control signal to photosensitive pixel in row 2 to drive the corresponding latched electrical signal output … of photosensitive pixel in row 2 and so on, t _1m And at the moment, providing an output control signal for the photosensitive pixel of the mth row so as to drive the latching electric signal output corresponding to the photosensitive pixel of the mth row. As can be seen, the time required for all the photosensitive pixels in the photosensitive device 20 to perform the light sensing and output the photosensitive signals is t _1m -t ₁₁ . The sensing speed of the light sensing device 20 is improved because the light sensing time of the light sensing pixels is saved.

Further, in some embodiments, the second driving circuit 242 is configured to: after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of second scanning lines line by line from beginning to end according to the arrangement sequence of the plurality of second scanning lines, and controlling the latch electric signals corresponding to the plurality of photosensitive pixels to be output; and providing the output control signals to the plurality of second scanning lines line by line from the tail to the head, and controlling the latch electric signals corresponding to the plurality of photosensitive pixels to be output.

Referring to fig. 7, fig. 7 illustrates a timing when the photo sensing device shown in fig. 4 performs photo sensing in such a manner that the photo sensing device outputs a photo sensing signal by sensing light twice at the same time. In particular, t ₁ At the moment, providing a first scanning driving signal and a second scanning driving signal to all photosensitive pixels of all rows to control all photosensitive pixels to perform light sensing, and at t ₂ And controlling all the photosensitive pixels to finish executing the light sensing at all times, and latching the electric signals generated when the photosensitive pixels execute the light sensing. t is t ₂₁ Controlling the output of the latch electric signal corresponding to the photosensitive pixel of the 1 st line at time t ₂₂ The latch electric signal output … corresponding to the photosensitive pixel of the 2 nd row is controlled at the moment, and the like, and t _2m Controlling the latch electric signal corresponding to the photosensitive pixel of the mth row to be output at any time; t is t ₃₁ Controlling the output of the latch electric signal corresponding to the photosensitive pixel of the mth row at the moment ₃₂ Controlling the output of the latch electric signal corresponding to the photosensitive pixel of the m-1 th line at any time, and repeating the steps until t _3m And controlling the output of the latch electric signal corresponding to the photosensitive pixel of the 1 st row at any time. As can be seen from the foregoing, after the photosensitive signal is turned off by the third switch, the first capacitor c1 cannot form a loop, so that the latch of the photosensitive signal is implemented, but due to the characteristics of the transistors, even if the fourth transistor T4 is turned off, a small amount of charges may leak through the fourth transistor T4, so that when the output time of the photosensitive signal is different, the collected photosensitive signal may affect the consistency of the photosensitive information due to the charge leakage, and especially the photosensitive signal with a large output time interval may be output. Therefore, the embodiment of the invention enables the photosensitive signals to be read twice by outputting the photosensitive signals twice, thereby balancing the read-out waiting time of different photosensitive pixels. The photosensitive signals read twice are accumulated, and the final photosensitive signal can be obtained. Taking the photosensitive pixels in the 1 st and 2 nd rows as an example, the waiting time of the photosensitive pixel in the 1 st row during the first signal reading is t ₂₁ -t ₂ The waiting time of the photosensitive pixel of the 2 nd line is t ₂₂ -t ₂ (ii) a The waiting time of the photosensitive pixel of the 1 st line during the second signal reading is t _3m -t ₂ The waiting time of the photosensitive pixel of the 2 nd line is t _3m-1 -t ₂ . Therefore, after two signal readings, the total waiting time of the 1 st line of photosensitive pixels is t ₂₁ -t ₂ +t _3m -t ₂ The total waiting time of the photosensitive pixels of the 2 nd line is t ₂₂ -t ₂ +t _3m-1 -t ₂ . Therefore, the total waiting time of the 1 st line of photosensitive pixels is equal to the total waiting time of the 2 nd line of photosensitive pixels, that is, the total waiting time of each 1 line of photosensitive pixels is equal, so that the influence of charge leakage on photosensitive signal acquisition is solved by reading the photosensitive signals of the same line of photosensitive pixels twice, and the sensing precision is improved.

Further, in some embodiments, the second driving circuit 242 is configured to provide the output control signals to the plurality of photosensitive pixels point by point according to the distribution sequence of the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing, so as to control the latch electrical signals output by the plurality of photosensitive pixels. In the implementation mode of the invention, the latching electric signals corresponding to the photosensitive pixels are output point by point, so that only one signal reading channel is arranged, thereby saving the cost of the photosensitive device. Moreover, because the signal reading speed is high, the influence of charge leakage on photosensitive signal acquisition can be avoided to a certain extent through the rapid reading of the signals.

In some embodiments, with continued reference to fig. 4, the photo-sensing driving circuit further includes a signal processing unit 25, the data lines of the photo-sensing device 20 shown in fig. 4 are all connected to the signal processing unit 25, and the signal processing unit 25 can be integrated into a detection chip through a silicon process. Of course, the signal processing unit 25 and the photosensitive driving unit 24 may be integrated into a single processing chip. Specifically, the signal processing unit 25 is configured to read the electrical signals output by the photosensitive pixels 22, and obtain predetermined biometric information of a target object in contact with or in proximity to the photosensitive device 20 based on the read electrical signals. It is understood that since the electric signals generated when the light sensing pixels 22 perform light sensing are latched, more sufficient time and flexibility are provided for signal reading of the signal processing unit 25, and sensing time is also saved and sensing speed is increased. In addition, in order to acquire accurate and effective electrical signals, the signal processing unit 25 may perform multiple readings on the latched electrical signals corresponding to the photosensitive pixels 22 within a second predetermined time.

In some embodiments, the signal processing unit 25 includes a plurality of processing channels, and optionally, each processing channel is connected to a corresponding data line. However, alternatively, each processing channel may be correspondingly connected to at least two data lines, and the electrical signals on one data line are selected to be read each time, then the electrical signals on the other data line are selected again in a time-division multiplexing manner, and so on until the electrical signals on all the data lines are read. In this way, the number of processing lanes can be reduced, thereby saving the cost of the photosensitive device 20.

Referring to fig. 8, fig. 8 shows another circuit configuration of one of the photosensitive pixels 22 of fig. 1. A photosensitive pixel 22 In the present embodiment has a first input terminal In1 ', a second input terminal In 2', a third input terminal In3 ', a fourth input terminal In4, a fifth input terminal In5, and a first output terminal Out 1' and a second output terminal Out2. The light sensing control signal comprises a first scanning driving signal and a second scanning driving signal. The light-sensing pixel 22 includes a sensing unit including a switching unit 221 ' and a light-sensing unit 222 ', and a signal output unit 223 '. The switch unit 221 ' receives a reference signal Vref through the third input terminal In3 ', and In addition, the switch unit 221 ' receives a first scanning driving signal through the first input terminal In1 ', and receives a second scanning driving signal through the fourth input terminal In4 ', and when receiving the first scanning driving signal and the second scanning driving signal, the switch unit transmits the reference signal Vref to the first branch circuit 2221 and the second branch circuit 2222 of the light sensing unit 222 ', respectively, so as to drive the light sensing unit 222 ' to perform light sensing. The photosensitive unit 222' receives a light signal when performing light sensing, and converts the received light signal into a corresponding electrical signal when receiving the light signal. The light sensing is finished after the light sensing unit 222' performs light sensing for a predetermined time, and a light sensing signal generated by performing the light sensing is latched. The signal output unit 223 ' receives a constant current signal Is through the fifth input terminal In5 and receives the output control signal through the second input terminal In2 ', so that the constant current signal Is transmitted to the conversion circuit 2231, and the conversion circuit 2231 converts the constant current signal Is into two different current signals according to the electrical signal at the first end of the first branch circuit 2221 and the electrical signal at the first end of the second branch circuit 2222, and outputs the two different current signals from the first output terminal Out1 ' and the second output terminal Out2.

Optionally, the first scanning driving signal, the second scanning driving signal and the output control signal are all pulse signals, and the duration of the high level signal in the first scanning driving signal is a first predetermined time, the duration of the high level signal in the output control signal is a second predetermined time, the duration of the high level signal in the second scanning driving signal is a third predetermined time, and the third predetermined time is greater than the first predetermined time.

In some embodiments, the photosensitive unit 222' includes a first branch circuit 2221 and a second branch circuit 2222. The first branch circuit 2221 is configured to perform optical sensing, that is, receive an optical signal, and convert the received optical signal into a corresponding electrical signal; the second branch circuit 2222 is used for maintaining the electrical signal of the first terminal of the second branch circuit 2222 at the amplitude of the reference signal Vref. Specifically, the photosensitive unit 222 'is similar to the photosensitive unit 222 shown in fig. 2, and the photosensitive unit 222' further includes a second capacitor c2 in addition to the photosensitive unit 222 shown in fig. 2, and the first capacitor c1 and the photosensitive device are the first branch circuit 2221 of the photosensitive unit 222 ', and the second capacitor c2 is the second branch circuit 2222 of the photosensitive unit 222'.

Regarding the first branch circuit 2221, it is defined herein that the cathode of the photodiode D1 and the first plate of the first capacitor c1 are the first end of the first branch circuit 2221, and the anode of the photodiode D1 and the second plate of the first capacitor c1 are the second end of the first branch circuit 2221. The operation of the first branch circuit 2221 can be implemented as described above. In the second branch circuit 2222, the first plate of the second capacitor c2 is used for receiving the reference signal Vref transmitted by the switch unit 221', and the second plate is used for receiving a fixed electrical signal, such as the ground signal NGND. The reference signal Vref charges the second capacitor c2, so that the voltage Vn across the first plate of the second capacitor c2 gradually rises and remains unchanged after reaching the amplitude of the reference signal Vref. It should be noted that, here, the first plate of the second capacitor c2 is defined as the first end of the second branch circuit 2222, and the second plate of the second capacitor c2 is defined as the second end of the second branch circuit 2222.

Further, in some embodiments, the switching unit 221 includes a fifth transistor T5 and a sixth transistor T6, an eighth transistor T8. The fifth transistor T5, the sixth transistor T6, and the eighth transistor T8 are, for example, but not limited to, any one or more of a triode, a MOS transistor, and a thin film transistor. Taking a MOS transistor as an example, the fifth transistor T5 includes a fifth control electrode C5, a ninth transmission electrode S9 and a tenth transmission electrode S10, where the fifth control electrode C5 is a gate of the MOS transistor, the ninth transmission electrode S9 is a drain of the MOS transistor, and the tenth transmission electrode S10 is a source of the MOS transistor. The sixth transistor T6 includes a sixth control electrode C6, an eleventh transmission electrode S11, and a twelfth transmission electrode S12, where the sixth control electrode C6 is a gate of the MOS transistor, the eleventh transmission electrode S11 is a drain of the MOS transistor, and the twelfth transmission electrode S12 is a source of the MOS transistor. The eighth transistor T8 includes a fifth control electrode C8, a fifteenth transmission electrode S15 and a sixteenth transmission electrode S16, wherein the eighth control electrode C8 is a gate of the MOS transistor, the fifteenth transmission electrode S15 is a drain of the MOS transistor, and the sixteenth transmission electrode S16 is a source of the MOS transistor.

The fifth control electrode C5 and the sixth control electrode C6 are both connected to the first input end In 1' and are configured to receive a first scan driving signal; the ninth transmission electrode S9 and the eleventh transmission electrode S11 are both connected to the third input terminal In 3' for receiving the reference signal Vref; the tenth transmitting electrode S10 is connected to the first end of the first branch circuit 2221 of the light sensing unit 222 ', and is configured to transmit the reference signal Vref to the first branch circuit 2221 of the light sensing unit 222' when the fifth transistor T5 is turned on; the twelfth transmitting electrode S12 is connected to the first end of the second branch circuit 2222 of the light sensing unit 222 ', and is used for transmitting the reference signal Vref to the second branch circuit 2222 of the light sensing unit 222' when the sixth transistor T6 is turned on.

The eighth control electrode C8 is connected to the fourth input end In 4' and configured to receive the second scan driving signal; the fifteenth transfer electrode S15 is connected to the first plate of the first capacitor c1, and the sixteenth transfer electrode S16 is connected to the first electrode (e.g., the cathode of the photodiode) of the light sensing device. And the first plate of the first capacitor c1 is used for connecting the signal output unit 223 ', i.e. the first plate of the first capacitor c1 is connected with the signal transmission unit 223'.

In some embodiments, the signal output unit 223' in the present embodiment includes a seventh transistor T7 and a conversion circuit 2231. The seventh transistor T7 is, for example, but not limited to, any one or more of a triode, a MOS transistor, and a thin film transistor. Taking a MOS transistor as an example, the seventh transistor T7 includes a seventh control electrode C7, a thirteenth transmission electrode S13 and a fourteenth transmission electrode S14, where the seventh control electrode C7 is a gate of the MOS transistor, the thirteenth transmission electrode S13 is a drain of the MOS transistor, and the fourteenth transmission electrode S14 is a source of the MOS transistor. The seventh control electrode C7 is connected with the second input end In 2' and is configured to receive the output control signal; the thirteenth transfer electrode S11 Is connected to the fifth input terminal In5 for receiving a constant current signal Is, and the fourteenth transfer electrode S14 Is connected to the switching circuit 2231. The seventh transistor T7 Is turned on according to the output control signal to transmit the constant current signal Is to the conversion circuit 2231.

Further, the switching circuit 2231 includes a differential pair transistor having three input terminals and two output terminals, wherein one input terminal Is connected to the fourteenth transmission electrode S14 of the seventh transistor T7, and Is configured to receive the constant current signal Is transmitted from the seventh transistor T7; the other two input terminals are correspondingly connected to the first terminal of the first branch circuit 2221 (i.e., the negative electrode of the photodiode D1 and the first plate of the first capacitor c 1) and the first terminal of the second branch circuit 2222 (i.e., the first plate of the second capacitor c 2); the two output terminals convert the constant current signal Is into two different current signals Ip and In according to the electrical signal Vp at the first terminal of the first branch circuit 2221 and the electrical signal Vn at the first terminal of the second branch circuit 2222, and the sum of the amplitudes of the two different current signals Is equal to the amplitude of the constant current signal Is.

Specifically, the conversion circuit 2231 includes a ninth transistor T9 and a tenth transistor T10. The ninth transistor T9 and the tenth transistor T10 are, for example, but not limited to, any one or more of a triode and a MOS transistor. Taking a MOS transistor as an example, the tenth transistor T10 includes a tenth control electrode C10, a nineteenth transfer electrode S19, and a twentieth transfer electrode S20, wherein the ninth control electrode C9 is a gate of the MOS transistor, the nineteenth transfer electrode S19 is a drain of the MOS transistor, and the twentieth transfer electrode S20 is a source of the MOS transistor. The ninth transistor T9 includes a ninth control electrode C9, a seventeenth transmission electrode S17 and an eighteenth transmission electrode S18, wherein the ninth control electrode C9 is a gate of the MOS transistor, the seventeenth transmission electrode S17 is a drain of the MOS transistor, and the eighteenth transmission electrode S18 is a source of the MOS transistor.

A ninth control electrode C9 of the ninth transistor T9 is connected to the first terminal of the first sub-circuit 2221 (e.g., the first plate of the first capacitor C1); the seventeenth transmission electrode S17 Is connected to the fourteenth transmission electrode S14 of the seventh transistor T7 for receiving the constant current signal Is transmitted from the seventh transistor T7; the eighteenth transmission electrode S18 is connected to the first output terminal Out 1' and is configured to output a current signal Ip. A tenth control electrode C10 of the tenth transistor T10 is connected to a first terminal of the second branch circuit 2222 (e.g., a first plate of the second capacitor C2); the nineteenth transmission electrode S19 Is connected to the fourteenth transmission electrode S14 of the seventh transistor T7, and Is configured to receive the constant current signal Is transmitted by the seventh transistor T7; the twentieth transmission electrode S20 is connected to the second output terminal Out2 for outputting another current signal In.

Further, the tenth transistor T10 and the ninth transistor T9 constitute a differential pair transistor, when the voltage Vp at the ninth control electrode C9 of the ninth transistor T9 and the voltage Vn at the tenth control electrode C10 of the tenth transistor T10 are equal, the differential pair transistor is in a balanced state, and the eighteenth transmission electrode S18 of the ninth transistor T9 and the twentieth transmission electrode S20 of the tenth transistor T10 output current signals having equal amplitudes. When there is a voltage difference between the voltage Vp at the ninth control electrode C9 of the ninth transistor T9 and the voltage Vn at the tenth control electrode C10 of the tenth transistor T10, the differential pair transistors output two differential electrical signals having different amplitudes. By inputting the two differential electrical signals with different amplitudes to the two input ends of the differential amplifier, corresponding amplified electrical signals can be obtained.

Referring to fig. 9, fig. 9 shows a signal sequence of the photosensitive pixel 22 of fig. 8 when performing light sensing, wherein Vp is a voltage on the first plate of the first capacitor c1, i.e., a voltage on the cathode of the photodiode D1; vn is the voltage on the first plate of the second capacitor c 2; in is the current signal output by the first output terminal Out 1', and Ip is the current signal output by the second output terminal Out2.

At time t1, a first scan driving signal is input through the first input terminal In1 ', and a second scan driving signal is input through the fourth input terminal In 4'. The fifth transistor T5 and the sixth transistor T6 are turned on according to the high level signal, and the eighth transistor T8 is turned on according to the high level signal.

When the fifth transistor T5 is turned on, the reference signal Vref is transmitted to the cathode of the photodiode D1 through the ninth and tenth transmission electrodes S9 and S10. Since the photodiode D1 has an equivalent capacitance therein, the reference signal Verf charges the equivalent capacitance in the photodiode D1, so that the voltage at the cathode of the photodiode D1 gradually rises and remains unchanged after reaching the voltage value of the reference signal Vref. Meanwhile, when the eighth transistor T6 is turned on, the reference signal Vref passes through the fifth transistor T5 and then is transmitted to the first plate of the first capacitor c1 through the eighth transistor T8, so as to charge the first capacitor c1, and the voltage Vp on the first plate of the first capacitor c1 gradually rises and remains unchanged after reaching the voltage value of the reference signal Vref.

When the sixth transistor T6 is turned on, the reference signal Vref is transmitted to the first plate of the second capacitor c2 through the eleventh transmission electrode S11 and the twelfth transmission electrode S12, so as to charge the second capacitor c2, and the voltage Vn on the first plate of the second capacitor c2 gradually increases and remains unchanged after reaching the voltage value of the reference signal Vref.

At time t2, the first scan driving signal changes from high level to low level, and the second scan driving signal is still a high level signal. Therefore, the first input terminal In1 'becomes a low level signal, the fourth input terminal In 4' is still a high level signal, the fifth transistor T5 and the second transistor T2 are both turned off, the eighth transistor T8 is still turned on, and at this time, the first capacitor c1 and the photodiode D1 form a discharge circuit, that is, the first capacitor c1 discharges the photodiode D1, and the voltage Vp on the first plate of the first capacitor c1 gradually decreases. If no optical signal is irradiated on the photodiode D1, the current inside the photodiode D1 is very weak, so that the voltage Vp on the first plate of the first capacitor c1 is basically kept unchanged; when the photodiode D1 is irradiated with an optical signal, a current signal proportional to the optical signal is generated inside the photodiode D1, and the stronger the optical signal is, the higher the current generated by the photodiode D1 is, so that the falling speed of the voltage Vp on the first plate of the first capacitor c1 is faster. When the sixth transistor T6 is turned off, the second capacitor c2 cannot form a discharge loop, and the voltage Vn on the first plate of the second capacitor c2, i.e. the reference signal Vref, is kept constant.

At time t3, the second scan driving signal is changed from a high level signal to a low level signal. Therefore, the fourth input terminal In4 'becomes a low level signal, the eighth transistor T8 is turned off, the first capacitor c1 cannot form a discharge loop, the voltage Vp on the first plate of the first capacitor c1 remains unchanged, and thus the photosensitive signal obtained by the photosensitive unit 222' is latched.

At time t4, the output control signal is input through the second input terminal In 2', and the output control signal is a high level signal. Since the output control signal is a high level signal, the seventh transistor T7 is turned on, and the conversion circuit 2231 converts the constant current signal into two electrical signals and outputs the two electrical signals. If the amplitudes of the voltage Vp and the voltage Vn are the same, the differential pair transistor of the conversion circuit 2231 is in a balanced state, and the electrical signal output by the first output terminal Out 1' is equal to the electrical signal output by the second output terminal Out2. If the amplitudes of the voltage Vp and the voltage Vn are not the same, that is, there is a certain difference, the differential pair transistor of the conversion circuit 2231 outputs two current signals with different amplitudes. And the sum of the amplitudes of the two current signals is equal to the amplitude of the constant current signal. After the light sensing unit 222' performs the light sensing, the electrical signal Vp at the first end of the first branch circuit 2221 gradually decreases, and the electrical signal Vn at the first end of the second branch circuit 2222 maintains Vref, so that a voltage difference exists between the electrical signal Vn and the electrical signal Vp, and the more the electrical signal Vp decreases, the larger the voltage difference is. Therefore, as shown in fig. 9, since the eighth transistor T8 is turned off from time T3, the voltage Vp is maintained by the first capacitor cl, and the voltage Vn is also maintained by the second capacitor c 2. Therefore, when the seventh transistor T7 is turned on at time T4, the amplitude of the current signal Ip output by the first output terminal Out 1' corresponds to the amplitude of the electrical signal Vp, and the amplitude of the current signal In output by the second output terminal Out2 corresponds to the amplitude of the electrical signal Vn. Further, since the voltage of the electric signal Vp decreases, the amplitude of the current signal In increases compared to the current amplitude In the equilibrium state, and the amplitude of the current signal Ip decreases compared to the current amplitude In the equilibrium state. The two paths of differential signals are input into the differential amplifier and then output electric signals which are amplified by one time compared with one path of electric signals, so that the signal amplification effect is achieved.

At time T5, the output control signal is converted from a high level signal to a low level signal, so that the second input terminal In2 'becomes a low level signal, the seventh transistor T7 is turned off, and the first output terminal Out 1' and the second output terminal Out2 stop outputting electrical signals, that is, become low level signals. In the period between the time t5 and the time t4, corresponding current signals are read from the first output end Out1 'and the second output end Out2, and according to the two current signals, a current signal generated by the light sensing performed by the light sensing unit 222' can be obtained, so that the biological characteristic information of the target object is obtained.

Further, during the third predetermined time Δ t2 between the time t3 and the time t2, the light sensing unit 222' performs the light sensing, and latches the electrical signal generated when the light sensing is performed at the time t 3. The third predetermined time Δ t2 may be a fixed value or a variable value. Since the larger the optical signal received by the photodiode D1 is, the faster the voltage Vp is reduced, the magnitude of Δ t2 is adjusted according to the intensity of the received optical signal in order to accurately and effectively obtain the photosensitive signal. Specifically, the greater the optical signal intensity, the shorter Δ t 2; the smaller the optical signal intensity, the longer Δ t2.

Further, since the light sensing signal generated when the light sensing unit 222 'performs light sensing is latched, the interval between the time t4 and the time t3 can be flexibly set, and all the light sensing units 222' can perform light sensing simultaneously, so that the control timing sequence is simple, the time for reading the whole light sensing is short, the sensing time can be shortened, and the user experience can be improved. Alternatively, to prevent charge leakage of the latch signal during the readout waiting process, the latched signal output is controlled each time each of the photosensitive units 222' finishes performing the light sensing and reaches the fifth predetermined time (e.g., t4-t 3).

In the embodiment of the present invention, the switch unit 221 'is not only used to drive the light sensing unit 222' to perform light sensing, but also used to control the light sensing unit 222 'to finish performing light sensing, and latch the electrical signal generated when the light sensing unit 222' performs light sensing, so that the light sensing pixels in different rows can perform light sensing simultaneously, and even all the light sensing pixels perform light sensing simultaneously, thereby providing sufficient time and flexibility for output control of light sensing signals. In addition, the photosensitive pixels 22 enable the current signals generated by the photosensitive unit 222' performing the photo sensing to be output in a two-way differential signal manner through the differential pair transistor structure, so that the amplification of the electrical signals is realized, and in addition, the two-way differential signals are both the output of the current signals relative to the voltage signals, so that the anti-interference capability of the signals is improved, and the sensing precision of the photosensitive device 20 is improved.

In some embodiments, referring to fig. 10, the difference from the light-sensitive pixel 22 shown in fig. 8 is: in the photosensitive pixel 22 according to the embodiment of the invention, the tenth transfer electrode S10 of the fifth transistor T5 is connected to the first plate of the first capacitor c1. After the fifth transistor T5 and the sixth transistor T6 are turned off, due to the characteristics of the transistors, even if the transistors are in an off state, a certain leakage phenomenon occurs in the transistors, and thus, part of the charges on the second capacitor c2 leaks from the sixth transistor T6, thereby causing leakage imbalance. In contrast, in the embodiment of the present invention, the first transistor T1 is connected to the first plate of the first capacitor c1, so that even if there is a leakage phenomenon after the fifth transistor T5 and the sixth transistor T6 are turned off, the electric leakage of the first capacitor c1 and the electric leakage of the second capacitor c2 are consistent, that is, the problem of unbalanced leakage is solved, and the sensing accuracy of the light sensing device 20 is improved.

Further, referring to fig. 11, the photosensitive device 20 further includes a scan line group, a data line group, and a signal reference line group electrically connected to the plurality of photosensitive pixels 22. The scanning line group comprises a first scanning line group consisting of a plurality of first scanning lines, a second scanning line group consisting of a plurality of second scanning lines and a third scanning line group consisting of a plurality of third scanning lines, the data line group comprises a plurality of data lines, and the signal reference line group comprises a plurality of signal reference lines. Taking the photosensitive array 201 in fig. 1 as an example, in the photosensitive array 201, a row of photosensitive pixels in the X direction includes n photosensitive pixels 22 arranged at intervals, and a column of photosensitive pixels in the y direction includes m photosensitive pixels 22 arranged at intervals, so that the photosensitive array 201 includes m × n photosensitive pixels 22 in total. Correspondingly, the first scanning line group comprises m first scanning lines, and the m first scanning lines are arranged at intervals along the Y direction, such as G11, G12, … G1m; the second scanning line group comprises m second scanning lines, and the m second scanning lines are also arranged at intervals along the Y direction, such as G21, G22, … G2m; the third scanning line group comprises m third scanning lines which are also arranged at intervals along the Y direction, such as G31, G32, … G3m; the signal reference line group comprises m signal reference lines which are arranged at intervals along the Y direction, such as L1, L2, … Lm; the data line group comprises n data lines, and the n data lines are arranged at intervals along the X direction, such as Sn1, sn2, … Sn-1 and Sn. Of course, the scan line groups, the data line groups and the signal reference line groups of the photosensitive devices 20 may be distributed in other regular or irregular manners. In addition, since the first scanning line, the second scanning line, the third scanning line, the signal reference line and the data line have conductivity, the first scanning line, the second scanning line, the third scanning line, the signal reference line and the data line at the crossing position are isolated by an insulating material.

Specifically, the first scan line is connected to the first input terminal In1 'of the photosensitive pixel 22, the second scan line is connected to the second input terminal In 2' of the photosensitive pixel 22, the signal reference line is connected to the third input terminal In3 'of the photosensitive pixel 22, the third scan line is connected to the fourth input terminal In 4' of the photosensitive pixel 22, the first data line is connected to the first output terminal Out1 'of the photosensitive pixel 22, the second data line is connected to the second output terminal Out 2' of the photosensitive pixel 22, and the third data line is connected to the w-th input terminal In5 of the photosensitive pixel 22. For convenience of wiring, the first scanning line, the second scanning line, the third scanning line and the signal reference line are all led out from the X direction, and the first data line, the second data line and the third data line are led out from the Y direction.

In some embodiments, the photosensitive device 20 further includes a photosensitive driving circuit, and the photosensitive driving circuit is further configured to: driving all photosensitive pixels in a photosensitive device to simultaneously perform light sensing, and controlling all the photosensitive pixels to finish the light sensing after the photosensitive pixels start to perform the light sensing; and after all the photosensitive pixels finish executing the light sensing, sequentially controlling the latching electric signals corresponding to the plurality of photosensitive pixels to be output.

Further, with reference to fig. 11, the photosensitive driving circuit includes a photosensitive driving unit 24, and the first scan line, the second scan line, the third scan line and the signal reference line are all connected to the photosensitive driving unit 24. Specifically, referring to fig. 12, the photosensitive driving unit 24 includes a first driving circuit 241 'for providing a first scanning driving signal, a second driving circuit 242' for providing an output control signal, a signal reference circuit 243 'for providing a reference signal Vref, and a third driving circuit 244' for providing a second scanning driving signal. The circuits of the photosensitive driving unit 24 can be integrated into a control chip through silicon process, but the circuits of the photosensitive driving unit 24 can also be formed separately. For example, the first driving circuit 241 'and the second and third driving circuits 242' and 244 'are formed on the same substrate together with the photosensitive pixels 22, and the signal reference circuit 243' is connected to a plurality of signal reference lines on the photosensitive device 20 through a flexible circuit board.

In some embodiments, the reference circuit 243 'is used for providing the reference signal Vref, and the reference circuit 243' is selectively electrically connected to the first branch circuit 2221 of the photosensitive unit 222 'through a fourth switch (e.g., a fifth transistor T5 in the switch unit 221' shown in fig. 8) of the photosensitive pixel 22. When the fourth switch is turned off, the reference signal Vref is transmitted to the first sub-circuit 2222 of the light sensing unit 222' through the turned-off fourth switch. Meanwhile, the reference circuit 243 ' may be electrically connected to the second branch circuit 2222 of the photosensitive unit 222 ' selectively via a fifth switch (e.g., the sixth transistor T6 of the switch unit 221 ' shown in fig. 8) of the photosensitive pixel 22. When the fifth switch is closed, the reference signal Vref is transmitted to the second branch circuit 2222 of the light sensing unit 222' through the closed fifth switch.

The first driving circuit 241 ' is electrically connected to the first scan line of the photosensitive device 20, and is configured to provide a first scan driving signal to the fourth switch and the fifth switch in all the photosensitive pixels 22, and the third driving circuit 244 ' is electrically connected to the third scan line of the photosensitive device 20, and is configured to provide a second scan driving signal to the seventh switch (for example, the eighth transistor T8 of the switching unit 221 ' shown in fig. 8) in all the photosensitive pixels 22 while the first driving circuit 241 ' provides the first scan driving signal, so as to control the fourth switch, the fifth switch, and the seventh switch to be turned on and off, and when the first predetermined time arrives, control the fourth switch and the fifth switch to be turned off, so as to drive the photosensitive unit 222 ' to start performing the photo sensing; when the third predetermined time is reached, the seventh switch is controlled to be turned off, so that the photosensitive unit 222 'is controlled to finish performing the light sensing, and the photosensitive signal generated by the photosensitive unit 222' is latched by the first capacitor c1.

The second driving circuit 242 'is electrically connected to the second scan line of the photosensitive device 20, and is configured to sequentially provide an output control signal to the sixth switches of the plurality of photosensitive pixels 22 after controlling the photosensitive unit 222 to end performing the photosensitive sensing, for example, after the seventh switch is turned off and reaches a fifth predetermined time (at time T4 shown in fig. 7), so as to control the sixth switches (for example, the seventh transistor T7 of the signal output unit 223' shown in fig. 6) to be turned on, and control the sixth switches to be turned off when the second predetermined time is reached. In the second predetermined time, the converting circuit 2231 converts the constant current signal into two different current signals according to the electrical signal generated when the photosensitive unit 222' performs the light sensing, and outputs the two different current signals.

Further, the control manner of the plurality of photosensitive pixels 22 by the second driving circuit 242' is consistent with the control manner of the plurality of photosensitive pixels 22 by the second driving circuit 242, that is, the output control signal is provided to the sixth switches of the plurality of photosensitive pixels 22 line by line or in an interlaced manner, so as to control the latch signals of the plurality of photosensitive pixels 22 to be output line by line or in an interlaced manner. And according to the distribution sequence of the photosensitive pixels 22, providing the output control signals to the plurality of photosensitive pixels 22 line by line from beginning to end, and providing the output control signals to the plurality of photosensitive pixels 22 line by line from end to perform two-time reading on the latch signals of the same photosensitive pixel 22. And a sixth switch that supplies an output control signal to the plurality of photosensitive pixels 22 point by point in the distribution order of the photosensitive pixels to control the latch signals of the plurality of photosensitive pixels 22 to be output point by point. The detailed control process and the advantageous effects are described with reference to the foregoing embodiments.

In some embodiments, with continued reference to fig. 11, the photo-sensing driving circuit further includes a signal processing unit 25, the data lines of the photo-sensing device 20 shown in fig. 11 are all connected to the signal processing unit 25, and the signal processing unit 25 can be integrated into a detection chip through a silicon process. Of course, the signal processing unit 25 and the photosensitive driving unit 24 may be integrated into a single processing chip. Specifically, the signal processing unit 25 is configured to read current signals output from the first output terminal Out 1' and the second output terminal Out2 by the photosensitive pixels 22, and obtain predetermined biometric information of a target object contacting or approaching the photosensitive device 20 based on the read electrical signals. It is understood that since the electrical signals generated when the light-sensing pixels 22 perform light sensing are latched, more sufficient time and flexibility are provided for signal reading by the signal processing unit 25, while sensing time is saved and sensing speed is increased. In addition, in order to acquire accurate and effective electrical signals, the signal processing unit 25 may perform multiple readings on the latched electrical signals corresponding to the photosensitive pixels 22 within a second predetermined time.

In some embodiments, the signal processing unit 25 includes a plurality of processing channels, and optionally, each processing channel is connected to a corresponding data line. However, alternatively, each processing channel may be correspondingly connected to at least two data lines, and the electrical signal on one data line is selected to be read each time in a time-division multiplexing manner, and then the electrical signal on the other data line is selected, and so on until the electrical signals on all the data lines are read. In this way, the number of processing lanes can be reduced, thereby saving the cost of the photosensitive device 20.

In some embodiments, referring to fig. 13, fig. 13 shows a structure of a photosensitive device according to another embodiment of the invention. The photosensitive device 20 further includes a photosensitive panel 200, the photosensitive panel 200 further includes a substrate 26, and a plurality of photosensitive pixels 22 are disposed on the substrate 26. Alternatively, the light-sensitive pixels 22 are distributed in an array. The photosensitive driving circuit is used for driving the photosensitive pixels to perform light sensing and controlling the photosensitive pixels to output electric signals generated when the photosensitive pixels perform the light sensing. The photosensitive pixels 22 are configured to receive the light signals from the top and convert the received light signals into corresponding electrical signals when performing the light sensing, so that the photosensitive areas of the plurality of photosensitive pixels 22 define a sensing area 203, and the areas outside the sensing area 203 are non-sensing areas 202. For the convenience of wiring layout, the non-sensing region 202 is used to set the driving circuits, such as the above-mentioned photosensitive driving circuits, required by the photosensitive pixels 22 to perform the photosensitive. Alternatively, the non-sensing region 202 is used to set a wire bonding area for electrical connections to connect. For example, taking the photosensitive device 20 shown in fig. 11 as an example, the first driving circuit 241 'and the second driving circuit 242', the third driving circuit 244 ', the reference circuit 243' are all formed on the substrate 26. Alternatively, the first driving circuit 241 ', the second driving circuit 242', the third driving circuit 244 ', and the reference circuit 243' are electrically connected to the photosensitive pixels 22 through electrical connectors (e.g., flexible circuit boards).

In some embodiments, the signal processing unit 25 may be selectively formed on the substrate 26 or electrically connected to the photosensitive pixels 22, for example, through an electrical connector (e.g., a flexible circuit board) according to the type of the substrate 26. For example, when the substrate 26 is a silicon substrate, the signal processing unit 25 may be formed on the substrate 26, or may be electrically connected to the photosensitive pixels 22 through a flexible circuit board, for example; when the substrate 26 is an insulating substrate, the signal processing unit 25 needs to be electrically connected to the photosensitive pixels 22, for example, through a flexible circuit board.

In some embodiments, the photosensitive device 20 is a photosensitive chip for sensing biometric information of a target object contacting or approaching the photosensitive device 20. Optionally, the photosensitive device 20 is a fingerprint sensing chip for sensing a fingerprint image of a finger of a user.

Further, based on the above photosensitive device, the embodiment of the invention further provides a light sensing method of the photosensitive device. Referring to fig. 14, fig. 14 shows specific steps of a light sensing method of a light sensing device according to an embodiment of the present invention, the light sensing method of the light sensing device includes the following steps:

s11, providing a first scanning driving signal and a second scanning driving signal to all photosensitive pixels so that all the photosensitive pixels start to perform light sensing when first preset time is reached, and finish performing the light sensing when third preset time is reached so as to latch electric signals generated when the light sensing of the photosensitive pixels is performed;

and S12, after all the photosensitive pixels finish performing the light sensing, sequentially providing an output control signal to the plurality of photosensitive pixels so as to control the latch electric signals corresponding to the plurality of photosensitive pixels to be output.

The light sensing method is applied to the collection of preset biological characteristic information of an object on a light sensing device, and whether the identity of the object is legal or not is determined according to the collected preset biological characteristic information, such as fingerprint identification. Specifically, based on the photosensitive device 20 shown in fig. 4 and the photosensitive pixel structure shown in fig. 2, step S11 specifically includes: supplying a first scan driving signal to the first switches (e.g., the first transistors T1 in the switch unit 221 shown in fig. 2) in all the photosensitive pixels 22, and simultaneously supplying a second scan driving signal to the third switches (e.g., the fourth transistors T4 in the switch unit 221 shown in fig. 3) in all the photosensitive pixels 22 to control the first switches and the third switches in all the photosensitive pixels 22 to be closed, and when a first predetermined time is reached, controlling the first switches to be opened, the photosensitive unit 222 starts to perform light sensing; when the third predetermined time is reached, the third switch is controlled to be turned off, and the light sensing unit 222 finishes performing the light sensing.

Step S12 specifically includes: after the third switch of the switch unit 221 is turned off, the output control signal is sequentially provided to the second switch (e.g., the second transistor T2 in the signal output unit 223 shown in fig. 3) to control the second switch of the signal output unit 223 to be closed, so as to output the electrical signal generated when the light sensing unit 222 in the light sensing pixel 22 performs light sensing.

Based on the photosensitive device 20 shown in fig. 11 and the photosensitive pixel structure shown in fig. 8, step S11 specifically includes: supplying the first scan driving signal to the fourth switch (e.g., the fifth transistor T5 in the switch unit 221 'shown in fig. 8) and the fifth switch (e.g., the sixth transistor T6 in the switch unit 221' shown in fig. 8) in all the photosensitive pixels 22, and simultaneously supplying the second scan driving signal to the seventh switch (e.g., the eighth transistor T8 in the switch unit 221 'shown in fig. 8) in all the photosensitive pixels 22, so as to control the fourth switch and the fifth switch, and the seventh switch in all the photosensitive pixels 22 to be turned off, and when the first predetermined time is reached, controlling the fourth switch and the fifth switch to be turned off, the photosensitive unit 222' starts to perform the light sensing; when the third predetermined time is reached, the seventh switch is controlled to be turned off, the light sensing unit 222 'finishes performing the light sensing, and the first capacitor cl latches an electric signal generated when the light sensing unit 222' performs the light sensing.

Step S12 specifically includes: after the seventh switch of the switch unit 221 'is turned off, the output control signal is sequentially provided to the sixth switch (e.g., the seventh transistor T7 of the signal output unit 223' shown in fig. 6) to control the sixth switch of the signal output unit 223 'to be closed, so that the conversion circuit receives a constant electrical signal, converts the constant electrical signal into two different electrical signals according to the electrical signal latched by the photosensitive unit 222', and outputs the two different electrical signals.

Further, in certain embodiments, step S12 comprises: and after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of photosensitive pixels line by line or in an interlaced mode until the latching electric signals corresponding to all the photosensitive pixels are all output.

With continued reference to fig. 6, the light sensing apparatus performs light sensing in such a manner that light sensing is performed while outputting light sensing signals line by line. In particular, t ₁ At the moment, providing a first scanning driving signal and a second scanning driving signal to all photosensitive pixels of all rows to control all photosensitive pixels to perform light sensing, and at t ₂ And controlling all the photosensitive pixels to finish executing the light sensing at all times, and latching the electric signals generated when the photosensitive pixels execute the light sensing. t is t ₁₁ At the moment, providing an output control signal for the photosensitive pixel of the 1 st row to drive the latch electric signal output corresponding to the photosensitive pixel of the 1 st row, t ₁₂ At time, providing output control signal to photosensitive pixel in row 2 to drive the corresponding latched electrical signal output … of photosensitive pixel in row 2 and so on, t _1m And at the moment, providing an output control signal for the photosensitive pixel of the mth row so as to drive the latching electric signal output corresponding to the photosensitive pixel of the mth row. As can be seen, the time required for all the photosensitive pixels in the photosensitive device 20 to perform the light sensing and output the photosensitive signals is t _1m -t ₁₁ . The sensing speed of the photosensitive device 20 is improved because the photosensitive time of the photosensitive pixels is saved.

Further, in certain embodiments, step S12 comprises: after all photosensitive pixels finish executing the light sensing, according to the distribution sequence of the photosensitive pixels, the output control signals are provided to the photosensitive pixels line by line from head to tail, and then the output control signals are provided to the photosensitive pixels line by line from tail to head, so that the electric signals output twice are accumulated to obtain the final electric signal.

With continued reference to fig. 7, the light sensing apparatus performs light sensing in a manner of sensing light twice at the same time to output a light sensing signal. In particular, t ₁ At the moment, providing a first scanning driving signal and a second scanning driving signal for all the photosensitive pixels of the row to control all the photosensitive pixels to perform light sensing, and at t ₂ And controlling all the photosensitive pixels to finish executing the light sensing at any time, and latching electric signals generated when the photosensitive pixels execute the light sensing. t is t ₂₁ Controlling the output of the latch electric signal corresponding to the photosensitive pixel of the 1 st line at time t ₂₂ The latch electric signal output … corresponding to the photosensitive pixel of the 2 nd row is controlled at the moment, and the like, and t _2m Controlling the output of the electric signals latched by the photosensitive pixels of the mth row at any time; t is t ₃₁ Controlling the output of the latched electric signal corresponding to the photosensitive pixel of the mth row at the moment ₃₂ Controlling the output of the electric signal latched by the photosensitive pixel of the m-1 th row at any time, and so on, t _3m And the time control unit controls the output of the electric signals latched by the photosensitive pixels of the 1 st row. As can be seen from the foregoing, after the photosensitive signal is turned off by the third switch, the first capacitor c1 cannot form a loop, so that the latch of the photosensitive signal is implemented, but due to the characteristics of the transistors, even if the fourth transistor T4 is turned off, a small amount of charges may leak through the fourth transistor T4, so that when the output time of the photosensitive signal is different, the collected photosensitive signal may affect the consistency of the photosensitive information due to the charge leakage, and especially the photosensitive signal with a large output time interval may be output. Therefore, the embodiment of the invention enables the photosensitive signals to be read twice by outputting the photosensitive signals twice, thereby balancing the read-out waiting time of different photosensitive pixels. The photosensitive signals read twice are accumulated to obtain the final photosensitive signal. Taking the photosensitive pixels in the 1 st and 2 nd rows as an example, the waiting time of the photosensitive pixels in the 1 st row during the first signal reading is t ₂₁ -t ₂ The waiting time of the photosensitive pixel of the 2 nd line is t ₂₂ -t ₂ (ii) a Waiting for line 1 photosensitive pixel during second signal readIs m between t _3m -t ₂ The waiting time of the photosensitive pixel of the 2 nd line is t _3m-1 -t ₂ . Therefore, after two signal readings, the total waiting time of the 1 st line of photosensitive pixels is t ₂₁ -t ₂ +t _3m -t ₂ The total waiting time of the photosensitive pixels of the 2 nd line is t ₂₂ -t ₂ +t _3m-1 -t ₂ . Therefore, the total waiting time of the 1 st line of photosensitive pixels is equal to the total waiting time of the 2 nd line of photosensitive pixels, that is, the total waiting time of each line of photosensitive pixels is equal, so that the influence of charge leakage on photosensitive signal acquisition is solved by reading the photosensitive signals of the same line of photosensitive pixels twice, and the sensing precision is improved.

Further, in certain embodiments, step S12 comprises: and after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of photosensitive pixels point by point according to the distribution sequence of the plurality of photosensitive pixels.

In the embodiment of the invention, the electric signals latched by the photosensitive pixels are output point by point, so that only one signal reading channel is arranged, thereby saving the cost of the photosensitive device. Moreover, because the signal reading speed is high, the influence of charge leakage on photosensitive signal acquisition can be avoided to a certain extent through the rapid reading of the signals.

Further, referring to fig. 15 and 16, fig. 15 shows a structure of an electronic apparatus according to an embodiment of the present invention, fig. 16 shows a cross-sectional structure of the electronic apparatus shown in fig. 15 along a line I-I according to an embodiment, and fig. 16 shows only a partial structure of the electronic apparatus. The electronic device comprises the photosensitive device with any one of the implementation structures, and is used for displaying images of the electronic device and sensing the biological characteristic information of a target object contacting or approaching the electronic device.

Examples of the electronic devices include, but are not limited to, consumer electronics, home electronics, vehicle-mounted electronics, financial terminal products, and other suitable types of electronic products. The consumer electronic products include mobile phones, tablet computers, notebook computers, desktop displays, all-in-one computers, and the like. The household electronic products are intelligent door locks, televisions, refrigerators, wearable equipment and the like. The vehicle-mounted electronic product is a vehicle-mounted navigator, a vehicle-mounted DVD and the like. The financial terminal products are ATM machines, terminals for self-service business handling and the like. The electronic device shown in fig. 15 is a mobile terminal such as a mobile phone, but the above-mentioned biometric sensing module can also be applied to other suitable electronic products, and is not limited to the mobile terminal such as a mobile phone.

Specifically, the front surface of the mobile terminal 3 is provided with a display device (not shown) including a display panel 300, and a protective cover 400 is disposed over the display panel 300. Optionally, the screen ratio of the display panel 300 is high, for example, more than 80%. The screen occupation ratio refers to a ratio of the display area 305 of the display panel 300 to the front area of the mobile terminal 3. The photosensitive panel 200 in the photosensitive device 20 (see fig. 4 and 8) is a panel structure adapted to the display panel 300 and is correspondingly disposed below the display panel 300. If the display panel 300 is in a flexible curved shape, the light sensing panel 200 is also in a flexible curved shape. Therefore, the light-sensing panel 200 may have a curved surface structure as well as a planar structure. Thus, the lamination assembly of the photosensitive panel 200 and the display panel 300 is facilitated.

Since the photo sensing panel 200 is located below the display panel 300, the display panel 300 has a light transmission region through which the light signal reflected by the target object passes, so that the photo sensing panel 200 can receive the light signal passing through the display panel 300, convert the received light signal into an electrical signal, and acquire predetermined biometric information of the target object contacting or approaching the electronic device according to the converted electrical signal.

In the embodiment of the present invention, in addition to the effect of the light sensing device 20 described in the above embodiment, the electronic device further utilizes the light signal emitted by the display panel 300 to sense the biometric information of the target object, and no additional light source is needed, so that not only the cost of the electronic device is saved, but also the biometric information sensing of the target object in the display area 305 of the touch or touch display panel 300 is realized. In addition, the photosensitive device 20 can be independently manufactured and then the electronic equipment is assembled, thereby accelerating the manufacturing of the electronic equipment.

When the mobile terminal 3 is in a bright screen state and in the biometric information sensing mode, the display panel 300 emits a light signal. When an object contacts or approaches the display area, the light sensing device 20 receives the light signal reflected by the object, converts the received light signal into a corresponding electrical signal, and obtains predetermined biometric information of the object, such as fingerprint image information, according to the electrical signal. Thus, the light sensing device 20 can sense a target object contacting or approaching any position of the display area.

In some embodiments, the display panel 300 is not limited to an OLED display device, but any display device that can achieve a display effect and has a light-transmitting region through which a light signal passes is within the scope of the present invention. In addition, the display panel 300 may be a bottom emission structure, a top emission structure, or a double-sided light-transmitting structure, and the display screen may be a rigid screen made of a rigid material or a flexible screen made of a flexible material.

In some embodiments, the light sensing panel 200 is used to perform biometric information sensing of a target object anywhere within the display area of the display panel 300. For example, specifically, for example, please refer to fig. 15, fig. 16 and fig. 17 in combination, the display panel 300 has a display area 305 and a non-display area 306, the display area 305 is defined by light emitting areas of all the display pixels 32 of the display panel 300, an area outside the display area 305 is the non-display area 306, and the non-display area 306 is used for setting circuits such as a display driving circuit for driving the display pixels 32 or a circuit bonding area for connecting a flexible circuit board. The photosensitive panel 200 has a sensing region 203 and a non-sensing region 204, the sensing region 203 is defined by the sensing regions of all the photosensitive pixels 22 of the photosensitive panel 200, the region outside the sensing region 203 is the non-sensing region 204, and the non-sensing region 204 is used for setting circuits such as the photosensitive driving unit 24 for driving the photosensitive pixels 22 to perform optical sensing or a circuit bonding region for connecting a flexible circuit board. The shape of the sensing region 203 is consistent with the shape of the display region 305, and the size of the sensing region 203 is larger than or equal to the size of the display region 305, so that the light sensing panel 200 can sense the predetermined biometric information of the target object contacting or approaching any position of the display region 305 of the display panel 300. Further, the area of the photosensitive panel 200 is smaller than or equal to the area of the display panel 300, and the shape of the photosensitive panel 200 is consistent with the shape of the display panel 300, so that the assembly of the photosensitive panel 200 and the display panel 300 is facilitated. However, alternatively, in some embodiments, the area of the photosensitive panel 200 may be larger than that of the display panel 300.

In some embodiments, the sensing region 203 of the light sensing panel 200 may also be smaller than the display region 305 of the display panel 300, so as to realize sensing of the predetermined biometric information of the target object in a local region of the display region 305 of the display panel 300.

Further, the display device is further used for performing touch sensing, and when the display device detects the touch or the proximity of the target object, the position of the control display panel corresponding to the touch area emits light.

However, alternatively, in some embodiments, referring to fig. 18, fig. 18 shows a cross-sectional structure of the electronic device shown in fig. 15 along the I-I line according to another embodiment, and fig. 18 only shows a partial structure of the electronic device. The photosensitive module of the embodiment of the invention is applied to a mobile terminal 3, the front of the mobile terminal is provided with a display panel 300, and a protective cover 400 is arranged above the display panel 300. The screen ratio of the display panel 300 is high, for example, 80% or more. The screen occupation ratio refers to a ratio of an actual display area 305 of the display panel 300 to a front area of the mobile terminal. The middle-lower position of the actual display area 305 of the display panel 300 is provided with a bio-sensing area for the target object to touch, so as to sense the bio-characteristic information of the target object, for example, if the target object is a finger, the bio-sensing area is a fingerprint identification area for fingerprint identification. Correspondingly, a photosensitive device 20 is disposed below the display panel 300 at a position corresponding to the fingerprint identification area, and the photosensitive device 20 is used for acquiring a fingerprint image of a finger when the finger is placed in the fingerprint identification area. It is understood that the middle-lower position of the display panel 300 is a position where a user can conveniently touch the display panel 300 with a finger when the user holds the mobile terminal. Of course, the touch panel can be arranged at other positions which are convenient for finger touch.

In some embodiments, the electronic device further includes a touch sensor (not shown) by which a touch area of the target object on the protective cover 400 can be determined. The touch sensor employs capacitive touch sensing technology, but may be implemented in other ways, such as resistive touch sensing, pressure-sensitive touch sensing, and so on. The touch sensor is configured to determine a touch area of a target object when the target object contacts the protective cover 400, so as to drive display pixels corresponding to the touch area to be turned on and light sensing pixels to perform light sensing.

In some embodiments, the touch sensor is integrated with either the protective cover 400, the light-sensing panel 200, or the display panel 300. Through the integrated touch sensor, not only is the touch detection of a target object realized, but also the thickness of the electronic equipment is reduced, and the development of the electronic equipment towards the direction of lightness and thinness is facilitated.

In the description herein, references to the description of the terms "one embodiment," "certain embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and those skilled in the art can make changes, modifications, substitutions and alterations to the above embodiments within the scope of the present invention.

Claims

1. A light sensing method for a light sensing device, the light sensing device comprising a plurality of light sensing pixels, the method comprising: the photosensitive pixel comprises a photosensitive unit and a switch unit electrically connected with the photosensitive unit, the photosensitive unit comprises at least one photosensitive device, a first capacitor and a second capacitor, the switch unit comprises a fourth switch, a fifth switch and a seventh switch, the fourth switch and the seventh switch are connected with a first polar plate of the first capacitor, and a second polar plate of the first capacitor is grounded; the fifth switch is connected with a first polar plate of the second capacitor, and a second polar plate of the second capacitor is grounded; the fourth switch, the fifth switch and the seventh switch all use transistors, the first capacitor is connected with the photosensitive device in parallel, the photosensitive device adopts a photodiode, the cathode of the photodiode is connected with the first polar plate of the first capacitor through the seventh switch, and the anode of the photodiode is grounded; the light sensing method comprises the following steps:

providing a first scanning driving signal to fourth switches and fifth switches in all photosensitive pixels, and simultaneously providing a second scanning driving signal to seventh switches in all photosensitive pixels so as to control the fourth switches, the fifth switches and the seventh switches in all photosensitive pixels to be turned on and off, and after the fourth switches and the fifth switches are turned on at the same time for a first preset time, controlling the fourth switches and the fifth switches to be turned off so that the photosensitive units start to perform photosensitive sensing; after the photosensitive unit starts to perform light sensing for a third preset time, controlling the seventh switch to be switched on so that the photosensitive unit finishes performing the light sensing, and latching an electric signal generated when the photosensitive unit performs the light sensing by the first capacitor;

after all the photosensitive pixels finish executing the light sensing, sequentially providing an output control signal to the plurality of photosensitive pixels so as to control the latch electric signals corresponding to the plurality of photosensitive pixels to be output;

the photosensitive pixel further comprises a signal output unit electrically connected with the photosensitive unit, and the signal output unit comprises a sixth switch and a conversion circuit; the step of sequentially controlling the plurality of photosensitive pixels to output the electric signals generated when the plurality of photosensitive pixels perform the light sensing after the light sensing of all the photosensitive pixels is finished further comprises:

after a seventh switch of the switch unit is switched off, the output control signals are sequentially provided for the sixth switch to control the sixth switch of the signal output unit to be switched on, so that the conversion circuit receives a constant electric signal, and the constant electric signal is converted into two different electric signals according to the electric signal latched by the photosensitive unit and is output;

the conversion circuit comprises a differential pair transistor, the differential pair transistor is provided with three input ends and two output ends, one input end receives the constant electric signals through the sixth switch, the other two input ends are correspondingly connected with a first polar plate of the first capacitor and a first polar plate of the second capacitor, and the two output ends convert the input constant electric signals into two different electric signals according to the electric signals on the first polar plate of the first capacitor and the first polar plate of the second capacitor.

2. A light sensing method of a light sensing device as claimed in claim 1, wherein: the photosensitive pixels are distributed in an array; the step of sequentially providing the output control signals to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing specifically includes:

and after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of photosensitive pixels line by line or in an interlaced mode until the latching electric signals corresponding to all the photosensitive pixels are all output.

3. A light sensing method of a light sensing device as claimed in claim 1, wherein: the photosensitive pixels are distributed in an array; the step of sequentially providing the output control signal to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing specifically includes:

after all the photosensitive pixels finish executing the light sensing, according to the distribution sequence of the photosensitive pixels, the output control signals are provided to the photosensitive pixels line by line from head to tail, and then the output control signals are provided to the photosensitive pixels line by line from tail to head, so that the electric signals output twice are accumulated to obtain the final electric signals.

4. A light sensing method of a light sensing device as claimed in claim 1, wherein: the step of sequentially providing the output control signals to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing specifically includes:

and after all the photosensitive pixels finish performing the light sensing, providing the output control signals to the plurality of photosensitive pixels point by point according to the distribution sequence of the plurality of photosensitive pixels.

5. A light sensing method of a light sensing device as claimed in claim 1, wherein: the photosensitive pixel further comprises a signal output unit electrically connected with the photosensitive unit, and the signal output unit comprises a second switch; the step of sequentially providing an output control signal to the plurality of photosensitive pixels after all the photosensitive pixels finish performing the light sensing further includes:

6. A light sensing method of a light sensing device as claimed in claim 1, wherein: and the third preset time is dynamically adjusted according to the intensity of the received optical signal.

7. A light sensing method of a light sensing device as claimed in claim 6, wherein: the greater the intensity of the received optical signal, the shorter the third predetermined time; the smaller the intensity of the received optical signal, the longer the third predetermined time.

8. A light sensing method of a light sensing device as claimed in claim 1, wherein: the constant electrical signal is a constant current signal.

9. A light sensing method of a light sensing device as claimed in claim 1, wherein: the light sensing method further comprises: