CN108171179A

CN108171179A - Photosensitive circuit, photosensitive device and electronic equipment

Info

Publication number: CN108171179A
Application number: CN201711493101.7A
Authority: CN
Inventors: 李问杰
Original assignee: Shenzhen Sunwave Technology Co Ltd
Current assignee: Liuzhou Zibo Technology Co ltd
Priority date: 2017-12-30
Filing date: 2017-12-30
Publication date: 2018-06-15

Abstract

The present invention discloses a kind of photosensitive circuit, photosensitive device and electronic equipment.The photosensitive circuit includes：The optical signal received for receiving optical signal, and is converted to corresponding electric signal, to perform light sensing by sensing unit；The signal output unit controls signal, and when receiving the output control signal, the electric signal output generated when the sensing unit is performed light sensing for receiving an output.Photosensitive device includes above-mentioned photosensitive circuit；Electronic equipment includes the photosensitive device.

Description

Photosensitive circuit, photosensitive device and electronic equipment

Technical Field

The invention relates to a photosensitive circuit, a photosensitive device and an electronic device for sensing biological characteristic 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 embodiments of the present invention need to provide a photosensitive circuit, a photosensitive device, and an electronic apparatus.

A light sensing circuit according to an embodiment of the present invention includes:

a sensing unit for receiving the optical signal and converting the received optical signal into a corresponding electrical signal to perform optical sensing;

the signal output unit is used for receiving an output control signal and outputting an electric signal generated when the sensing unit executes light sensing when receiving the output control signal.

In the photosensitive circuit of the embodiment of the invention, the light sensing is carried out through the sensing unit, and the signal output unit is used for controlling the output of the electric signal generated when the sensing unit carries out the light sensing, so that the timely and effective output of the electric signal generated by the photosensitive unit is realized, and the sensing precision is improved.

In some embodiments, the sensing unit includes a switch unit and a light sensing unit; wherein,

the switch unit is used for receiving a reference signal and a first scanning driving signal, and transmitting the reference signal to the photosensitive unit when receiving the first scanning driving signal;

the photosensitive unit is used for receiving the reference signal transmitted by the switch unit, and starts to perform light sensing when first preset time is reached to generate a corresponding photosensitive signal.

In the photosensitive circuit of the embodiment of the invention, whether the photosensitive unit is driven to carry out light sensing is controlled by the switch unit, so that the independent control of the photosensitive unit is realized, and the sensing flexibility is improved.

In some embodiments, the first scan driving signal is a pulse signal, and a duration of a high level signal in the pulse signal is a first predetermined time; the switch unit is closed according to the first scanning driving signal and is disconnected when first preset time is reached, and the photosensitive unit starts to perform light sensing.

In some embodiments, the light sensing unit includes a light sensing device, and the light sensing device includes a first electrode for receiving the reference signal transmitted by the switching unit.

In some embodiments, the light sensing device is a photodiode, and a cathode of the photodiode is a first electrode of the light sensing device and is configured to receive the reference signal transmitted by the switching unit, and an anode of the photodiode receives a predetermined voltage signal.

In some embodiments, the light sensing unit further comprises a first capacitor; the first electrode plate of the first capacitor is used for receiving the reference signal transmitted by the switch unit, the second electrode plate of the first capacitor is connected with a preset voltage signal, and the first capacitor and the photosensitive device form a discharge loop when the first capacitor performs light sensing.

According to the embodiment of the invention, the capacitance capacity of the whole photosensitive unit is increased by arranging the first capacitor, so that the discharge speed of the photodiode is reduced, the reading time of the voltage signal on the cathode of the photodiode is more sufficient, and the sensing precision of the target object is improved.

In some embodiments, the first capacitor is a variable capacitor, or the first capacitor is a capacitor array composed of a plurality of capacitors. Because the first capacitor is set as a variable capacitor, the light sensing time of the light sensing pixel can be adjusted by adjusting the capacity of the first capacitor so as to adapt to the change of the ambient light, and thus, an accurate light sensing signal is obtained.

In some embodiments, the switching unit includes a first transistor, and the first transistor includes a first control electrode, a first transmission electrode, and a second transmission electrode; the first control electrode is connected with the first input end and used for receiving the first scanning driving signal, the first transmission electrode is used for receiving the reference signal, and the second transmission electrode is connected with the first electrode of the photosensitive device; the first transistor is turned on when receiving the first scan driving signal, and transmits the reference signal to a first electrode of the light sensing device.

In some embodiments, the signal output unit includes a second transistor and a buffer circuit; the buffer circuit is connected between the second transistor and the sensing unit and is used for buffering the electric signal generated by the sensing unit; the second transistor includes a second control electrode, a third transfer electrode, and a fourth transfer electrode; the second control electrode is connected with the second input end and used for receiving the output control signal, the third transmission electrode is used for being connected with the buffer circuit, and the second transistor is conducted when receiving the output control signal and outputs the buffered electric signal from the fourth transmission electrode.

In the embodiment of the invention, the buffer circuit plays a role of buffer isolation, isolates the electric signal generated by the photosensitive unit executing the photosensitive operation, and avoids the influence of other circuit loads on the sensing signal of the photosensitive unit, thereby obtaining an accurate photosensitive signal.

In some embodiments, the buffer circuit includes a third transistor, and the third transistor includes a third control electrode, a fifth transmission electrode, and a sixth transmission electrode; the third control electrode is used for being connected with the first electrode of the photosensitive device, the fifth transmission electrode is used for receiving a voltage signal, and the sixth transmission electrode is connected with the third transmission electrode of the second transistor.

In some embodiments, the output control signal is a pulse signal, and the duration of a high level signal in the pulse signal is a second predetermined time.

In some embodiments, the second predetermined time is dynamically adjusted according to the intensity of the optical signal received by the sensing unit.

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

In some embodiments, the switch unit is further configured to further include a fourth transistor, the fourth transistor includes a fourth control electrode, a seventh transmission electrode, and an eighth transmission electrode, the fourth control electrode is connected to the third input terminal and is configured to receive the second scan driving signal, the seventh transmission electrode is connected to the first electrode of the photo sensor, the eighth transmission electrode is connected to the first plate of the first capacitor, and the first plate of the first capacitor is connected to the signal transmission unit; wherein the high level signal in the second scan driving signal lasts for a third predetermined time, which is greater than the first predetermined time.

In the embodiment of the invention, the switch unit is not only used for driving the photosensitive unit to execute light sensing, but also used for controlling the photosensitive unit to finish the light sensing and latching the electric signal generated by the photosensitive unit executing the light sensing, so that the photosensitive pixels in different rows can execute the light sensing at the same time, even all the photosensitive pixels execute the light sensing at the same time, and thus, enough time and flexibility are provided for the output control of the photosensitive signals.

In some embodiments, the first capacitor is configured to latch a photo sensing signal generated when the photo sensing unit performs photo sensing when the photo sensing unit finishes photo sensing.

In the embodiment of the invention, the first capacitor is not only used for forming a discharge loop with the photosensitive device when light sensing is carried out, but also used for latching an electric signal generated by the light sensing when the light sensing is finished. Therefore, the photosensitive pixel of the embodiment of the invention has simple structure and small occupied space.

An embodiment of the present invention provides a photosensitive device including a plurality of photosensitive circuits according to any one of the above embodiments.

The photosensitive device comprises the plurality of photosensitive circuits, so that each photosensitive circuit can be independently controlled, and the sensing of the biological characteristic information of the target object contacting or approaching the photosensitive device is realized. In addition, because the photosensitive device is provided with the photosensitive circuit, the photosensitive device has the technical effect of the photosensitive circuit, and the sensing precision of the photosensitive device is improved.

In some embodiments, the photosensitive device further includes a photosensitive driving unit correspondingly connected to the scanning line group and the signal reference line group, and a signal processing unit connected to the data line group; the photosensitive driving unit is used for driving the photosensitive circuits to perform photosensitive sensing and controlling the photosensitive circuits to output electric signals generated when the photosensitive circuits perform photosensitive sensing; the signal processing unit is used for reading electric signals generated when the plurality of photosensitive circuits perform light sensing and acquiring preset biological characteristic information of a target object contacting or approaching the upper part of the photosensitive device according to the read electric signals.

In some embodiments, the photosensitive device is a photosensitive chip.

In some embodiments, the photosensitive device is used to sense fingerprint information.

An embodiment of the present invention provides an electronic device including the light sensing device according to any one of the above embodiments.

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 light-sensing 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 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, where 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 schematic circuit diagram of another embodiment of the light-sensing pixel of FIG. 1;

FIG. 7 is a timing diagram illustrating signals at nodes of the photosensitive pixel of FIG. 6 when performing light sensing;

FIG. 8 is a diagram illustrating a connection structure between a photosensitive pixel and a scan line, a data line and a signal reference line in a photosensitive device according to another embodiment of the present invention, wherein the photosensitive pixel has the structure shown in FIG. 6;

FIG. 9 is a block diagram of an embodiment of the photosensitive driving unit shown in FIG. 8;

FIG. 10 is a schematic view of a structure of a photosensitive panel in the photosensitive device according to an embodiment of the present invention;

FIG. 11 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. 12 is a cross-sectional view of one embodiment of the electronic device shown in FIG. 11 taken along line I-I, and FIG. 12 illustrates a partial structure of the electronic device;

FIG. 13 is a schematic diagram illustrating a position of a display region of a display panel and a sensing region of a photosensitive panel according to an embodiment of the present invention;

fig. 14 is a schematic sectional view of another embodiment of the electronic device shown in fig. 11 taken along line I-I, and fig. 14 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, the components and settings of a specific example 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 may recognize applications of other processes and/or uses 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 equipment executes the biological characteristic information sensing, the light source emits corresponding light signals, such as infrared light, so that the sensing of information of heart rate, blood oxygen concentration, veins and the like of a target object is realized.

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 distribution structure of photosensitive pixels in a photosensitive device, in which the photosensitive device 20 includes a plurality of photosensitive pixels 22, and the plurality of 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 and executing light sensing when receiving the light sensing control signal. When light sensing is performed, the sensing unit receives a light signal and converts the received light signal into a corresponding light sensing signal, namely an electric 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. Accordingly, the light-sensing pixel 22 may also be referred to as a light-sensing circuit. A light-sensitive pixel 22 of the present embodiment has a first input terminal In1, a second input terminal In2, a third input terminal In3, and a first output terminal Out 1. The light sensing control signal includes a first 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 the switch unit 221 further receives a first scan driving signal through the first input terminal In1 and transmits the reference signal Vref to the photosensitive unit 222 when receiving the first scan driving signal, so as to drive the photosensitive unit 222 to operate. The light sensing unit 222 is configured to receive a light signal and convert the received light signal into a corresponding electrical signal when 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 and the output control signal are both pulse signals, and a duration of a high level in the first scan driving signal is a first predetermined time, and a duration of a high level in the output control signal is a second predetermined time.

In some embodiments, the light sensing unit 222 includes at least one 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, photodiode D1, and alternatively, the light sensing device may also be a photo-resistor, a photo-transistor, a thin film transistor, or the like. 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 predetermined 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 is applied to the two ends of the photodiode D1 corresponding to the predetermined signal, a reverse voltage is formed across the photodiode D1, so as to drive the photodiode D1 to perform 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 therein, 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 reaches the reverse voltage driving the photodiode to operate, i.e., the photodiode D1 is in an operating state. Since the first scan driving signal is converted from the high level signal to the low level signal when the first predetermined time is reached, the switch unit 221 is turned off according to the low level signal, and a discharge loop is formed inside the photodiode D1. At this time, when 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 accordingly, i.e., decreases gradually. Further, since the larger the intensity of the optical signal, the larger the reverse current generated by the photodiode D1, the faster the voltage Vg on the negative node of the photodiode D1 drops.

Further, the light sensing unit 222 further includes at least one first capacitor c 1. The first capacitor c1 is used for forming a discharge circuit 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 photo sensing device, i.e., the first plate of the first capacitor c1 is connected to the cathode of the photodiode D1, and the second plate of the first capacitor c1 is connected to a predetermined electrical signal, e.g., the ground signal NGND. 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. 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 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 capacitance change of the first capacitor c1 is realized by controlling whether the plurality of capacitors are connected or not. Since the first capacitor c1 is set as a variable capacitor, the capacity of the first capacitor c1 is adjusted to adapt to the change of the received optical signal, so as to obtain 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 the first transistor T1 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 first transistor T1 includes a first control electrode C1, a first transfer electrode S1 and a second transfer electrode S2, wherein the first control electrode is a gate of the MOS transistor, the first transfer electrode S1 is a drain of the MOS transistor, and the second transfer electrode S2 is a source of the MOS transistor. 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 applied to the cathode of the photodiode D1 and the first plate of the first capacitor c1 through the first transfer electrode S1 and the second transfer electrode S2; the first transistor T1 is turned on and turned off after a first predetermined time, and 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 transfer electrode S3 and a fourth transfer electrode S4, wherein the second control electrode C2 is a gate of the MOS transistor, the third transfer electrode S3 is a drain of the MOS transistor, and the fourth transfer electrode S4 is a source of the MOS transistor. The second control electrode C2 is connected to the second input terminal In2 for receiving 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; the fourth transmission electrode S4 is connected to the first output terminal Out1, and is used for outputting the electric signal buffered by the buffer circuit.

Further, a buffer circuit is connected between the light sensing unit 222 and the second transistor T2 for buffering the electrical signal converted by the light sensing unit 222 and outputting 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, wherein 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 used for receiving an electrical signal generated when the photodiode D1 performs light sensing; the fifth transmitting electrode S5 is 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 change of the voltage Vg of the third control electrode C3, i.e., the voltage of the sixth transfer electrode S6 is not affected regardless of the change of the circuit load connected to the sixth transfer electrode S6. Also, due to the transistor characteristics, the voltage Vs is always lower than the voltage Vg by a threshold voltage, which is the threshold voltage of the 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 at each node when the photosensitive pixel 22 shown in fig. 2 performs light 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, such that the first transistor T1 is turned on and turned off after a first predetermined time (i.e., T2-T1) In which the reference signal Vref is transmitted to the cathode of the photodiode D1 and the first plate of the first capacitor c1 via the first transmission electrode S1 and the second transmission electrode S2. Since the photodiode D1 has an equivalent capacitance therein, the reference signal Verf charges the equivalent capacitance inside the photodiode D1, so that the voltage Vg at the cathode of the photodiode D1 gradually rises and remains unchanged after reaching the voltage value of the reference signal Vref. In addition, since the first capacitor c1 is connected in parallel with the photodiode D1, the reference signal Vref charges the first capacitor c1, so that the voltage on the first plate 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 to low, that is, the first input terminal In1 changes to low, the first transistor T1 is turned off, and a discharge loop is formed between the equivalent capacitor and the first capacitor c1 and the photodiode D1. When the photodiode D1 is illuminated by the optical signal, a current signal proportional to the optical signal is generated inside the photodiode D1, and thus the voltage Vg at the cathode of the photodiode D1 gradually decreases. Also, the stronger the optical signal, the faster the voltage Vg decreases. In addition, due to the voltage following characteristic of the third transistor T3, the voltage Vs on the sixth transfer electrode S6 of the third transistor T3 varies with the voltage Vg on the cathode electrode of the photodiode D1, and the voltage Vs is always lower than the voltage Vg by Vth, which is the threshold voltage of the third transistor T3. It should be noted that the first predetermined time is to ensure that the photodiode in the light sensing unit 22 and the first capacitor c1 are charged to the reference signal Vref.

At time T3, that is, after the light sensing unit 222 starts to perform the light sensing and reaches the fourth predetermined time (i.e., T3-T2), the output control signal is input through the second input terminal In2, the second transistor T2 is turned on according to the high level signal, and the voltage Vs on the sixth transmission electrode S6 of the third transistor T3 is output from the first output terminal Out1 through the third transmission electrode S3 and the fourth transmission electrode S4 of the second transistor T2. The voltage output from the first output terminal Out1 gradually rises from the low level to the voltage Vs on the sixth transmission electrode S6, and then changes with the change of the voltage Vs on the sixth transmission electrode S6. It should be noted that the fourth predetermined time is at least one clock cycle, and the fourth predetermined time cannot be too long, and certainly cannot be too short, so as to ensure that the light sensing signal generated when the light sensing unit 222 performs light sensing can be effectively and timely output.

At time T4, the output control signal changes from a high level signal to a low level signal, that is, the second input terminal In2 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 is gradually decreased to a low level. During the period between the time T4 and the time T3, that is, during the second predetermined time Δ T1, the voltage Vs on the sixth transfer electrode S6 of the third transistor T3 (which is equivalent to the voltage Vg on the cathode of the photodiode D1) is output from the first output terminal Out1 through the second transistor T2, so that the magnitude of the light sensing signal generated by the photodiode D1 due to the light signal received by the photodiode Out1 is obtained by reading the voltage signal of the first output terminal Out1, and the biometric information of the target object is generated.

Further, the second predetermined time Δ t1 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 t1 is adjusted according to the intensity of the received light signal in order to achieve accurate and efficient acquisition of the light sensing signal. Specifically, the greater the light signal intensity, the shorter the second predetermined time Δ t 1; the smaller the light signal intensity is, the longer the second predetermined time Δ t1 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 and a second scanning line group consisting of a plurality of second 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 photo-sensing array 201 in fig. 1 as an example, in the photo-sensing array 201, a row of photo-sensing pixels in the X direction includes n photo-sensing pixels 22 arranged at intervals, and a column of photo-sensing pixels in the Y direction includes m photo-sensing pixels 22 arranged at intervals, so that the photo-sensing array 201 includes m × n photo-sensing pixels 22 in total. Correspondingly, the first scan line group includes m first scan lines, and the m first scan lines are arranged at intervals along the Y direction, such as G11, G12, … G1 m; the second scan line group further includes m second scan lines, and the m second scan lines are also arranged at intervals along the Y direction, such as G21, G22, … G2 m; the signal reference line group comprises m signal reference lines, and the m signal reference lines are arranged at intervals along the Y direction, such as L1, L2, … Lm; the data line group comprises n data lines which are arranged at intervals along the X direction, such as S1, S2, … Sn-1 and 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 scan line, the second scan line, the signal reference line, and the data line have conductivity, the first scan line, the second scan line, the signal reference line, and the data line at the crossing position are isolated from each other by an insulating material.

Specifically, m first scan lines are correspondingly connected to the first input terminals In1 of the plurality of photosensitive pixels 22, m second scan lines are correspondingly connected to the second input terminals In2 of the plurality of photosensitive pixels 22, m signal reference lines are correspondingly connected to the third input terminals In3 of the plurality of photosensitive pixels 22, and n data lines are correspondingly connected to the first output terminals Out1 of the plurality of photosensitive pixels 22. For convenience of wiring, the first scanning line, the second 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, which is configured to provide a first scan driving signal and a reference signal Vref to the plurality of photosensitive pixels to drive the plurality of photosensitive pixels 22 to perform photosensitive sensing, and provide an output control signal to the plurality of photosensitive pixels after the photosensitive pixels 22 start performing photosensitive sensing, so as to control the photosensitive pixels 22 to perform electric signal output during photosensitive sensing.

Further, the plurality of photosensitive pixels 22 are distributed in an array, and the photosensitive driving circuit is further configured to: and providing a first scanning driving signal to the plurality of photosensitive pixels line by line or in an interlaced manner to drive the plurality of photosensitive pixels to execute the light sensing line by line or in an interlaced manner, and controlling the photosensitive pixels of the current line to execute the electric signal output generated by the light sensing after the photosensitive pixels of the current line are driven to start to execute the light sensing. Therefore, the photosensitive driving circuit can drive a row of photosensitive pixels to simultaneously perform light sensing at one time, thereby accelerating the sensing speed.

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, and the signal reference line of the photo-sensing device 20 are all connected to the photo-sensing driving unit 24. Referring to fig. 5, fig. 5 shows a structure of an embodiment of the sensing driving unit 24 in fig. 4. The photosensitive driving unit 24 includes a first driving circuit 241 which supplies a first scan driving signal, a second driving circuit 242 which supplies an output control signal, and a reference circuit 243 which supplies a reference signal Vref. The circuits of the photosensitive driving unit 24 can be integrated in one control chip through silicon process, but the circuits of the photosensitive driving unit 24 can also be separately formed in different control chips. For example, the first and second driving circuits 241 and 242 are formed on the same substrate together with the light-sensing pixels 22, and the reference circuit 243 is connected to a plurality of signal reference lines on the light-sensing device 20 through a connection member (e.g., 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) of the light-sensing pixel 22. 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 light sensing device 20, and is configured to provide a first scan driving signal to the first switch to control the first switch to be turned on, and when a first predetermined time is reached, control the first switch to be turned off, so as to drive the light sensing unit 222 to start to perform light sensing. Optionally, the first scan driving signal is a pulse signal, and a duration of a high level in the pulse signal is a first predetermined time, for example, t2-t1 shown in fig. 3. The first switch is closed according to the high level signal and is opened according to the low level signal.

The second driving circuit 242 is electrically connected to the second scan line of the photosensitive device 20, and is configured to provide an output control signal to a second switch (e.g., a second transistor T2 in the signal output unit 223 shown in fig. 2) of the photosensitive pixel 22 after the first switch is turned off and reaches a fourth predetermined time (e.g., T3-T2 shown in fig. 3), so as to control the second switch to be turned on, so that the photosensitive unit 222 performs a light sensing operation to output an electrical signal generated when performing the light sensing operation. Optionally, the output control signal is a pulse signal, and the duration of the high level in the pulse signal is a second predetermined time, for example, t4-t3 shown in fig. 3. The second switch is closed according to the high level signal and is opened according to the low level signal.

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 an electrical signal generated when the photosensitive unit 222 performs light sensing, and obtain predetermined biometric information of a target object contacting or approaching the photosensitive device according to the read electrical signal. It is understood that, in order to acquire an accurate and effective electrical signal, the signal processing unit 25 may read the electrical signal generated when the light sensing unit 222 performs light sensing for a plurality of times within the 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. 6, fig. 6 shows another circuit structure of one of the photosensitive pixels 22 in fig. 1. In the present embodiment, a photosensitive pixel 22 has a first input terminal In1 ', a second input terminal In 2', a third input terminal In3 ', a fourth input terminal, and a first output terminal Out 1'. The light sensing control signal comprises a first scanning driving signal and a second scanning driving signal. The photosensitive pixel 22 includes a switching unit 221 ', a photosensitive unit 222 ', and a signal output unit 223 '. The switch unit 221 ' receives a reference signal Vref through a third input terminal In3 ', and In addition, the switch unit 221 ' receives a first scanning driving signal through a first input terminal In1 ', receives a second scanning driving signal through a fourth input terminal In4, and transmits the reference signal Vref to the photosensitive unit 222 ' to drive the photosensitive unit 222 ' to perform photo sensing when receiving the first scanning driving signal and the second scanning driving signal, and ends the photo sensing after the photosensitive unit 222 ' starts to perform the photo sensing and continues for a predetermined time, and latches a photosensitive signal generated by performing the photo sensing. The photosensitive unit 222' receives a light signal and converts the received light signal into a corresponding electrical signal upon receiving the light signal. The signal output unit 223 'receives an output control signal through the second input terminal In 2', and outputs an electrical signal generated by the photosensitive unit 222 'from the first output terminal Out 1' according to the output control signal.

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.

Specifically, the structures of the photosensitive unit 222 'and the signal output unit 223' in the present embodiment are the same as those of the photosensitive unit 222 and the signal output unit 223 shown in fig. 2, and are not described again here. The switching unit 221' further includes a fourth transistor T4 in addition to the structure of the switching unit 221 shown in fig. 2. The fourth transistor T4 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 fourth transistor T4 includes a fourth control electrode C4, a seventh transfer electrode S7 and an eighth transfer electrode S8, wherein the fourth control electrode C4 is a gate of the MOS transistor, the seventh transfer electrode S7 is a drain of the MOS transistor, and the eighth transfer electrode S8 is a source of the MOS transistor. The fourth control electrode C4 is connected to the fourth input terminal In4 for receiving the second scan driving signal; the seventh transfer electrode S7 is connected to the first electrode of the photo sensing device (e.g., the cathode of the photodiode), and the eighth transfer electrode S8 is connected to the first plate of the first capacitor c 1. 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.

Referring to fig. 7, fig. 7 shows a signal timing sequence of the photosensitive pixel 22 of fig. 6 when performing light sensing, where Vg is a voltage on the first plate of the first capacitor C1, a light sensing signal latched when the light sensing unit 222' finishes light sensing, and a voltage on the third control electrode C3 of the third transistor T3; vs is a voltage on the sixth transfer electrode S8 of the third transistor T3.

At time t1, a first scan driving signal is input through the first input terminal In 1', 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. Since the photodiode D1 has an equivalent capacitance therein, the reference signal Verf charges the equivalent capacitance inside 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 to low, and the second scan driving signal remains high. At this time, the first input terminal In 1' becomes a low level signal, the first transistor T1 is turned off, 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 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 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 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 to low. 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 as to latch the photo-sensing signal generated when the photo-sensing unit 222' performs photo-sensing.

At time t4, an output control signal is inputted through the third input terminal In 3', 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 the voltage Vg on the first plate of the first capacitor c1 is output from the first output terminal Out 1' via the sixth transfer electrode S6 of the third transistor T3, the third transfer electrode S3 of the second transistor T2 and the fourth transfer electrode S4. The voltage output from the first output terminal Out 1' gradually rises from the low level to the voltage Vs on the sixth transmission electrode S6, and then changes with the change of the voltage Vs on the sixth transmission electrode S6. Since the first capacitor c1 latches the voltage Vg starting 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 Out 1' 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 low level, the second transistor T2 is turned off, and the voltage output by the first output terminal Out 1' gradually drops or remains unchanged. In order to ensure the effective output of the next signal, the output voltage of the first output terminal Out 1' is gradually decreased 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 of the photodiode D1 changed by receiving the optical signal can be obtained by reading the voltage signal of the first output terminal Out 1', 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 end light sensing, and latch the electrical signal generated by the light sensing unit 222' performing 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 efficient acquisition of the light sensing signal. Specifically, the greater the light signal intensity, the shorter the third predetermined time Δ t 2; the smaller the light signal intensity is, the longer the third predetermined time Δ t2 is.

Further, referring to fig. 8, 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 photo-sensing array 201 in fig. 1 as an example, in the photo-sensing array 201, a row of photo-sensing pixels in the X direction includes n photo-sensing pixels 22 arranged at intervals, and a column of photo-sensing pixels in the Y direction includes m photo-sensing pixels 22 arranged at intervals, so that the photo-sensing array 201 includes m × n photo-sensing pixels 22 in total. Correspondingly, the first scan line group includes m first scan lines, and the m first scan lines are arranged at intervals along the Y direction, such as G11, G12, … G1 m; 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, … G2 m; the third scanning line group comprises m third scanning lines, and the m third scanning lines are also arranged at intervals along the Y direction, such as G31, G32, … G3 m; the signal reference line group comprises m signal reference lines, and the m signal reference lines are arranged at intervals along the Y direction, such as L1, L2, … Lm; the data line group comprises n data lines which are arranged at intervals along the X direction, such as Sn1, Sn2, … Sn-1 and 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 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 In4 of the photosensitive pixel 22, and the data line is connected to the first output terminal Out 1' 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 light sensing driving circuit of the light sensing device 20 is further configured to: the first scanning driving signal and the second scanning driving signal are provided to the plurality of photosensitive pixels, so that after the photosensitive pixels 22 start to perform light sensing when the first preset time is reached, the photosensitive pixels are controlled to finish the light sensing when the third preset time is reached, electric signals generated when the photosensitive pixels perform the light sensing are latched, and an output control signal is provided to the plurality of photosensitive pixels to control the electric signals latched by the photosensitive pixels to be output.

Further, the plurality of photosensitive pixels 22 are distributed in an array, and the photosensitive driving circuit is further configured to: providing the first scanning driving signal and the second scanning driving signal to the plurality of photosensitive pixels line by line or in an interlaced manner so as to drive the plurality of photosensitive pixels to perform light sensing line by line or in an interlaced manner; or, the first scanning driving signal and the second scanning driving signal are provided to all the photosensitive pixels at the same time to drive all the photosensitive pixels to perform light sensing at the same time. Therefore, the photosensitive driving circuit can drive a row of photosensitive pixels at a time, and even all the photosensitive pixels can simultaneously perform light sensing, so that the sensing speed is increased.

Further, with reference to fig. 8, 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. 9, fig. 9 shows a structure of an embodiment of the photosensitive driving unit 24 in fig. 8. The photosensitive driving unit 24 includes a first driving circuit 241 ' that provides a first scan driving signal, a second driving circuit 242 ' that provides an output control signal, a signal reference circuit 243 ' that provides a reference signal Vref, and a third driving circuit 244 that provides 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 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 light sensing unit 222 'through a first switch (e.g., the first transistor T1 in the switch unit 221' shown in fig. 6). When the first switch is closed, the reference signal Vref is transmitted to the corresponding photosensitive 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 is configured to provide a first scan driving signal to the first switch to control the first switch to be closed, and when a first predetermined time (e.g., t2-t1 shown in fig. 7) is reached, control the first switch to be opened, so as to drive the photosensitive unit 222' 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 is configured to provide a second scan driving signal to a third switch (e.g., a fourth transistor T4 in the switch unit 221 'shown in fig. 6) while the first driving circuit 241' provides the first scan driving signal, so that the third switch is closed while the first switch is closed, and when the third switch is closed and reaches a third predetermined time (e.g., T3-T1 shown in fig. 7), the third switch is controlled to be opened, so as to control the photosensitive unit 222 'to end performing the photo sensing, and an electrical signal generated when the photosensitive unit 222' performs the photo sensing is latched by the first capacitor c 1.

The second driving circuit 242 'is electrically connected to the second scanning line of the photosensitive device 20, and is configured to provide an output control signal to the second switch (e.g., the second transistor T2 in the signal output unit 223' shown in fig. 6) after controlling the photosensitive unit 222 'to finish performing the light sensing, for example, when the third switch is turned off and reaches a fifth predetermined time (e.g., time T4 shown in fig. 7), and control the second switch to be turned on and continue for the second predetermined time, so as to output an electrical signal generated when the photosensitive unit 222' performs the light sensing.

In some embodiments, with continued reference to fig. 8, the photo-sensing driving circuit further includes a signal processing unit 25, the data lines of the photo-sensing device 20 shown in fig. 9 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 an electrical signal generated by the light sensing performed by the light sensing unit 222', and obtain predetermined biometric information of a target object contacting or approaching the light sensing panel according to the read electrical signal. It can be understood that, since the electrical signal generated when the photosensitive cell performs the light sensing is latched, the signal processing unit 25 is provided with more sufficient time and flexibility for signal reading, and the sensing time is saved and the sensing speed is increased. In addition, in order to acquire an accurate and effective electrical signal, the signal processing unit 25 may read the electrical signal generated when the light sensing unit 222' performs light sensing for a plurality of times within the second predetermined time.

In some embodiments, referring to fig. 10, fig. 10 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 photosensitive pixels 22 are distributed in an array. The photosensitive pixels 22 are configured to receive an optical signal from above and convert the received optical signal into a corresponding electrical signal, 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 convenience of wiring layout, the non-sensing region 202 is used to set a driving circuit required for the photosensitive pixels 22 to perform optical sensing, or to set a wiring bonding region for connection of an electrical connector. Some or even all of the circuits of the above-described photo-sensing driving circuit may be disposed on the substrate 26. For example, taking the photosensitive device 20 shown in fig. 4 as an example, the first driving circuit 241, the second driving circuit 242, and the reference circuit 243 are formed on the substrate 26. Alternatively, the first driving circuit 241, the second driving circuit 242, and the reference circuit 243 are electrically connected to the photosensitive pixels 22 through an electrical connector (e.g., a flexible circuit board).

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, referring to fig. 11 and 12, fig. 11 shows a structure of an electronic device according to an embodiment of the present invention, fig. 12 shows a cross-sectional structure of another embodiment of the electronic device shown in fig. 11 along the line I-I, and fig. 12 shows only a partial structure of the electronic device. 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 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. The electronic device shown in fig. 11 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 9) 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 a flexible curved surface, the light sensing panel 200 is also a flexible curved surface. Therefore, the light-sensing panel 200 may have a curved surface structure, instead of a flat surface 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 photosensitive device 20 described in the above embodiment, the electronic device further uses the optical 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 of the target object in the display area 305 contacting or touching the display panel 300 is sensed. 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. 11, fig. 12 and fig. 13 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 electronic device is convenient to assemble. 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. 14, fig. 14 shows a cross-sectional structure of the electronic device shown in fig. 11 along a line I-I of another embodiment, and fig. 14 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. A biological sensing area for a target object to touch is disposed at a middle-lower position of the actual display area 305 of the display panel 300 for sensing biological characteristic information of the target object, for example, if the target object is a finger, the biological 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 the 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 lit 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 circuit, comprising: the method comprises the following steps:

2. The light sensing circuit of claim 1, wherein: the sensing unit comprises a switch unit and a photosensitive unit; wherein,

the switch unit is used for receiving a reference signal and a first scanning driving signal and transmitting the reference signal to the photosensitive unit when receiving the first scanning driving signal;

3. The light sensing circuit of claim 2, wherein: the first scanning driving signal is a pulse signal, and the duration time of a high-level signal in the pulse signal is first preset time; the switch unit is closed according to the first scanning driving signal and is disconnected when first preset time is reached, and the photosensitive unit starts to perform light sensing.

4. The light sensing circuit of claim 2, wherein: the photosensitive unit comprises a photosensitive device, and the photosensitive device comprises a first electrode used for receiving the reference signal transmitted by the switch unit.

5. The light sensing circuit of claim 4, wherein: the light sensing device is a photodiode, the cathode of the photodiode is a first electrode of the light sensing device and is used for receiving the reference signal transmitted by the switch unit, and the anode of the photodiode receives a preset voltage signal.

6. The light sensing circuit of claim 4, wherein: the photosensitive unit further comprises a first capacitor; the first polar plate of the first capacitor is used for receiving the reference signal transmitted by the switch unit, the second polar plate of the first capacitor is connected with a preset voltage signal, and the first capacitor and the photosensitive device form a discharge loop when the sensing unit performs light sensing.

7. The light sensing circuit of claim 6, wherein: the first capacitor is a variable capacitor, or the first capacitor is a capacitor array composed of a plurality of capacitors.

8. The light sensing circuit of claim 4, wherein: the switch unit comprises a first transistor, and the first transistor comprises a first control electrode, a first transmission electrode and a second transmission electrode; the first control electrode is used for receiving the first scanning driving signal, the first transmission electrode is used for receiving the reference signal, and the second transmission electrode is connected with the first electrode of the photosensitive device; the first transistor is turned on when receiving the first scan driving signal, and transmits the reference signal to a first electrode of the light sensing device.

9. The light sensing circuit of any of claims 1-8, wherein: the signal output unit comprises a second transistor and a buffer circuit; the buffer circuit is connected between the second transistor and the sensing unit and is used for buffering the electric signal generated by the sensing unit; the second transistor includes a second control electrode, a third transfer electrode, and a fourth transfer electrode; the second control electrode is used for receiving the output control signal, the third transmission electrode is used for being connected with a buffer circuit, and the second transistor is conducted when receiving the output control signal and outputs a buffered electric signal through the fourth transmission electrode.

10. The light sensing circuit of claim 9, wherein: the buffer circuit comprises a third transistor, and the third transistor comprises a third control electrode, a fifth transmission electrode and a sixth transmission electrode; the third control electrode is used for being connected with the first electrode of the photosensitive device, the fifth transmission electrode is used for receiving a voltage signal, and the sixth transmission electrode is connected with the third transmission electrode of the second transistor.

11. The light sensing circuit of claim 9, wherein: the output control signal is a pulse signal, and the duration of a high level signal in the pulse signal is a second preset time.

12. The light sensing circuit of claim 11, wherein: and the second preset time is dynamically adjusted according to the intensity of the optical signal received by the sensing unit.

13. The light sensing circuit of claim 12, wherein: the greater the intensity of the received optical signal, the shorter the second predetermined time; the smaller the intensity of the received optical signal, the longer the second predetermined time.

14. The light sensing circuit of claim 9, wherein: the switching unit is further configured to, where the switching unit further includes a fourth transistor, where the fourth transistor includes a fourth control electrode, a seventh transmission electrode, and an eighth transmission electrode, the fourth control electrode is configured to receive the second scan driving signal, the seventh transmission electrode is connected to the first electrode of the light sensing device, the eighth transmission electrode is connected to the first plate of the first capacitor, and the first plate of the first capacitor is connected to the signal transmission unit; wherein the high level signal in the second scan driving signal lasts for a third predetermined time, which is greater than the first predetermined time.

15. The light sensing circuit of claim 14, wherein: the first capacitor is used for latching a photosensitive signal generated when the photosensitive unit performs light sensing when the photosensitive unit finishes light sensing.

16. A photosensitive device, characterized by: comprising a plurality of light sensing circuits according to any of claims 1-15.

17. A photosensitive device according to claim 16, wherein: the photosensitive device further comprises a photosensitive driving unit and a signal processing unit which are respectively electrically connected with the plurality of photosensitive circuits; the photosensitive driving unit is used for driving the photosensitive circuit to perform photosensitive sensing and controlling the photosensitive circuit to output an electric signal generated when the photosensitive circuit performs photosensitive sensing; the signal processing unit is used for reading the electric signals output by the photosensitive circuits and acquiring preset biological characteristic information of a target object contacting or approaching the upper part of the photosensitive device according to the read electric signals.

18. A photosensitive device according to claim 17, wherein: the photosensitive device is a photosensitive chip.

19. A photosensitive device according to claim 17, wherein: the photosensitive device is used for sensing fingerprint information.

20. An electronic device, characterized in that: comprising a photosensitive device according to any one of claims 16-19.