Fingerprint recognition sensor and driving method thereof, display device

Abstract

Embodiments of the present application provide a fingerprint identification sensor and a driving method thereof, and a display device, and relate to the technical field of display, to improve the accuracy of fingerprint identification. The fingerprint identification sensor comprises a fingerprint identification circuit, the fingerprint identification circuit comprises a first node, a photosensitive element and a control module, the photosensitive element is electrically connected with the first node and a common voltage structure respectively, the common voltage structure is used for providing a common voltage signal, the control module is electrically connected with a control signal line, and the control module is further coupled with the first node; when the control signal provided by the control signal line jumps from a non-enabled voltage to an enabled voltage, the common voltage signal jumps from a first voltage to a second voltage, (Ve-Vne)×(V2-V1) < 0, Vne is the voltage value of the non-enabled voltage, Ve is the voltage value of the enabled voltage, V1 is the voltage value of the first voltage, and V2 is the voltage value of the second voltage.

Description

[Technical Field]

[0001] This invention relates to the field of display technology, and in particular to a fingerprint recognition sensor, its driving method, and a display device. [Background Technology]

[0002] Display devices typically use the fingerprint recognition circuit in a fingerprint sensor to identify the ridges of a fingerprint. However, during the operation of the fingerprint recognition circuit, the node voltage is prone to oscillation, which can easily cause noise and lead to inaccurate recognition. [Summary of the Invention]

[0003] In view of this, embodiments of the present invention provide a fingerprint recognition sensor and its driving method and display device to improve the accuracy of fingerprint recognition.

[0004] On one hand, embodiments of the present invention provide a fingerprint recognition sensor, including multiple fingerprint recognition circuits. Each fingerprint recognition circuit includes a first node, a photosensitive element, and a control module. The photosensitive element is electrically connected to the first node and a common voltage structure, respectively. The common voltage structure is used to provide a common voltage signal. The control module is electrically connected to a control signal line and is also coupled to the first node.

[0005] When the control signal provided by the control signal line jumps from the disabled voltage to the enabled voltage, the common voltage signal jumps from the first voltage to the second voltage, where (Ve-Vne)×(V2-V1)<0, Vne is the voltage value of the disabled voltage, Ve is the voltage value of the enabled voltage, V1 is the voltage value of the first voltage, and V2 is the voltage value of the second voltage.

[0006] On the other hand, embodiments of the present invention provide a driving method for a fingerprint recognition sensor. The fingerprint recognition sensor includes multiple fingerprint recognition circuits. Each fingerprint recognition circuit includes a first node, a photosensitive element, and a control module. The photosensitive element is electrically connected to the first node and a common voltage structure for providing a common voltage signal. The control module is electrically connected to a control signal line and is used to turn on when the control signal line provides an enable voltage. The control module is also coupled to the first node.

[0007] The driving method includes: when the control signal provided by the control signal line jumps from a non-enable voltage to an enable voltage, the common voltage signal jumps from a first voltage to a second voltage, where (Ve-Vne)×(V2-V1)<0, Vne is the voltage value of the non-enable voltage, Ve is the voltage value of the enable voltage, V1 is the voltage value of the first voltage, and V2 is the voltage value of the second voltage.

[0008] In another aspect, embodiments of the present invention provide a display device, including a display panel and the aforementioned fingerprint recognition sensor.

[0009] One of the above technical solutions has the following beneficial effects:

[0010] During the operation of a fingerprint recognition circuit, when the detection light reflected from a finger shines on the photosensitive element, the element generates a leakage current, which in turn changes the potential of the first node. Since the intensity of the detection light reflected from the fingerprint valleys and ridges differs, the leakage current generated by the photosensitive element at different locations varies. Therefore, the potential change of the first node in the fingerprint recognition circuit can be used to determine whether a location corresponds to a fingerprint valley or ridge. Based on this working principle, it is clear that the stability of the first node's potential significantly affects the accuracy of fingerprint recognition.

[0011] Because the control module is coupled to the first node, when a voltage jump occurs in the control signal provided by the control signal line electrically connected to the control module, the parasitic capacitance of the transistor in the control module causes the voltage jump to further cause fluctuations in the potential of the first node, resulting in oscillations in the potential of the first node. To address this, this embodiment of the invention employs a stepped design for the common voltage signal received by the photosensitive element, making it no longer a fixed voltage. Thus, when a voltage jump occurs in the control signal, the effect of the opposite-direction voltage jump generated by the common voltage signal on the potential of the first node can be used to counteract the effect of the voltage jump in the control signal on the potential of the first node.

[0012] Taking Ve as an example where Vne is greater than V, when the control signal has a rising edge, the rising edge of the control signal will have a positive pull on the potential of the first node. At this time, by controlling the common voltage signal to have a falling edge, based on the effect of the parasitic capacitance of the photodiode, the falling edge can be used to have a negative pull on the potential of the first node. This negative pull can cancel out the positive pull on the first node caused by the rising edge of the control signal, thereby effectively suppressing the potential oscillation of the first node, improving the signal-to-noise ratio, and thus effectively improving the fingerprint recognition accuracy. [Attached Image Description]

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a top view of the fingerprint recognition sensor provided in an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of a fingerprint recognition circuit provided in an embodiment of the present invention;

[0016] Figure 3 for Figure 2 A corresponding timing diagram;

[0017] Figure 4 This is a schematic diagram of a fingerprint recognition circuit provided in an embodiment of the present invention;

[0018] Figure 5 for Figure 4 A corresponding timing diagram;

[0019] Figure 6 This is a schematic diagram of another circuit structure of the fingerprint recognition circuit provided in an embodiment of the present invention;

[0020] Figure 7 This is a schematic diagram of another circuit structure of the fingerprint recognition circuit provided in an embodiment of the present invention;

[0021] Figure 8 for Figure 7 A corresponding timing diagram;

[0022] Figure 9 This is a schematic diagram of a film structure of a fingerprint recognition sensor provided in an embodiment of the present invention;

[0023] Figure 10 This is a schematic diagram of a common voltage structure provided in an embodiment of the present invention;

[0024] Figure 11 This is another schematic diagram of the common voltage structure provided in the embodiment of the present invention;

[0025] Figure 12 for Figure 10 A connection diagram of the corresponding common voltage structure;

[0026] Figure 13 for Figure 11 A connection diagram of the corresponding common voltage structure;

[0027] Figure 14 This is another top view of the fingerprint recognition sensor provided in an embodiment of the present invention;

[0028] Figure 15 This is a schematic diagram of another structure of the common voltage structure provided in the embodiment of the present invention;

[0029] Figure 16 for Figure 15 A connection diagram of the corresponding common voltage structure;

[0030] Figure 17 This is a schematic diagram of a display device provided in an embodiment of the present invention.

Detailed Implementation Methods

[0031] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0033] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0034] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0035] This invention provides a fingerprint recognition sensor that can be attached to the backlight side of a display panel to enable fingerprint recognition functionality in the display device. Figures 1-3 As shown, Figure 1 This is a top view of the fingerprint recognition sensor provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of a fingerprint recognition circuit provided in an embodiment of the present invention. Figure 3 for Figure 2 According to a corresponding timing diagram, the fingerprint recognition sensor provided in this embodiment of the invention includes multiple fingerprint recognition circuits 1, each fingerprint recognition circuit 1 including a first node Q, a photosensitive element 2, and a control module 3.

[0036] Among them, the photosensitive element 2 can be a photodiode. The photosensitive element 2 is electrically connected to the first node Q and the common voltage structure 4 respectively. The common voltage structure 4 is used to provide a common voltage signal Vcom. The control module 3 is electrically connected to the control signal line cl. The control module 3 is used to turn on or off in response to the control signal provided by the control signal line cl. The control module 3 is also coupled to the first node Q.

[0037] When the control signal provided by the control signal line cl transitions from an enable voltage to an enable voltage, the common voltage signal Vcom transitions from a first voltage to a second voltage. Where (Ve-Vne)×(V2-V1)<0, Vne is the voltage value of the enable voltage (i.e., the voltage value used to control the control module 3 to be off), Ve is the voltage value of the enable voltage (i.e., the voltage value used to control the control module 3 to be on), V1 is the voltage value of the first voltage, and V2 is the voltage value of the second voltage.

[0038] For ease of understanding, the embodiments of the present invention use the same reference numerals to represent signal lines and the signals they provide. For example, in Figure 3 In the timing diagram shown, the reference numeral Rst indicates the control signal provided by the reset control signal line Rst.

[0039] In one setup method, see Figure 3 If Ve is greater than Vne, then correspondingly, V2 should be less than V1. In this method, when the control signal jumps from low to high, the common voltage signal Vcom needs to have a downward voltage transition; that is, when the control signal has a rising edge, the common voltage signal Vcom needs to have a falling edge. Alternatively, in another setting method, see [link to relevant documentation]. Figure 8 If Ve is less than Vne, then V2 should be greater than V1. In this mode, when the control signal jumps from high to low, the common voltage signal Vcom needs to have an upward voltage jump. That is, when the control signal has a falling edge, the common voltage signal Vcom needs to have a rising edge.

[0040] However, it should be noted that the above statements, "when the control signal is a rising edge, the common voltage signal Vcom is a falling edge" or "when the control signal is a falling edge, the common voltage signal Vcom is a rising edge," should allow for a certain degree of error. For example, within a few nanoseconds before and after the rising edge of the control signal, the falling edge of the common voltage signal Vcom should be considered as a corresponding transition edge of the two signals.

[0041] During the operation of the fingerprint recognition circuit 1, when the detection light reflected from the finger shines on the photosensitive element 2, the photosensitive element 2 will generate a leakage current under the influence of the light, thereby changing the potential of the first node Q. Since the intensity of the detection light reflected from the fingerprint valley and ridge is different, the leakage current generated by the photosensitive element 2 at different locations is different. Therefore, the potential change of the first node Q in the fingerprint recognition circuit 1 can be used to determine whether the location corresponds to a fingerprint valley or a fingerprint ridge. Based on this working principle, it can be seen that the stability of the potential of the first node Q greatly affects the accuracy of fingerprint recognition.

[0042] Since control module 3 is coupled to the first node Q, when the control signal provided by the control signal line cl, which is electrically connected to control module 3, experiences a voltage jump, the parasitic capacitance of the transistor in control module 3 will cause the voltage jump to further cause fluctuations in the potential of the first node Q, resulting in oscillations in the potential of the first node Q. To address this, this embodiment of the invention employs a stepped design for the common voltage signal Vcom received by photosensitive element 2, making it no longer a fixed voltage. Thus, when the control signal experiences a voltage jump, the effect of the opposite-direction voltage jump generated by the common voltage signal Vcom on the potential of the first node Q can be used to counteract the effect of the control signal's voltage jump on the potential of the first node Q.

[0043] Taking Ve as an example where Vne is greater than Vne, see [link / reference]. Figure 3 When the control signal has a rising edge, it will positively pull the potential of the first node Q. At this time, by controlling the common voltage signal Vcom to have a falling edge, based on the parasitic capacitance of the photodiode, this falling edge can be used to negatively pull the potential of the first node Q. This negative pull can cancel out the positive pull of the rising edge of the control signal on the first node Q, thereby effectively suppressing the potential oscillation of the first node Q, improving the signal-to-noise ratio, and thus effectively improving the fingerprint recognition accuracy.

[0044] Before describing the subsequent solutions, the embodiments of the present invention first take... Figure 2 The working principle of fingerprint recognition circuit 1 will be explained using the circuit structure shown as an example:

[0045] See Figure 2 The fingerprint recognition circuit 1 includes a driving module 5, a reading unit 6, and a reset unit 7. The driving module 5 may include a driving transistor M0, the gate of which is electrically connected to a first node Q, and the first terminal of which is electrically connected to a first voltage signal line VDD. The reading unit 6 may include a reading transistor M1, the gate of which is electrically connected to a reading control signal line Read, the first terminal of which is electrically connected to the second terminal of the driving transistor M0, and the second terminal of which is electrically connected to an output signal line Data. The reset unit 7 may include a reset transistor M2, the gate of which is electrically connected to a reset control signal line Rst, the first terminal of which is electrically connected to a second voltage signal line Vrst, and the second terminal of which is electrically connected to the gate of the driving transistor M0.

[0046] join Figure 3 The driving cycle of the fingerprint recognition circuit 1 includes an initialization period t1 and an exposure period t2, wherein the exposure period t2 includes a first reading period t21 and a second reading period t22.

[0047] During the initialization period t1, the reset control signal line Rst provides an enable voltage Ve to control the reset transistor M2 to turn on, and the first node Q is initialized using the signal provided by the second voltage signal line Vrst. After initialization, the potential of the first node Q is higher than the potential of the common voltage signal Vcom provided by the common voltage structure 4. At this time, the photosensitive element 2 is in the reverse bias cutoff state.

[0048] During the first reading period t21, the read control signal line Read provides an enable voltage Ve to control the read transistor M1 to turn on. Under illumination, the photosensitive element 2 generates leakage current under the illumination of the detection light reflected back from the finger, causing the potential of the first node Q to drop. The driving transistor M0 generates leakage current under the action of the first node Q potential and transmits it to the output signal line Data through the read transistor M1, causing the output signal line Data to output a reference voltage.

[0049] During the period between the first reading period t21 and the second reading period t22, the potential of the first node Q was continuously decreasing as the exposure time increased.

[0050] During the second reading period t22, the Read control signal line provides an enable voltage Ve to control the read transistor M1 to turn on. The drive transistor M0 generates leakage current under the action of the first node Q potential and transmits it to the output signal line Data through the read transistor M1, so that the output signal line Data outputs the detection voltage.

[0051] After acquiring the reference voltage and the detection voltage, the potential change of the first node Q can be known by judging the difference between the two, and then the intensity of the detection light sensed by the photosensitive element 2 can be known. In this way, the ridges and valleys of the fingerprint can be judged.

[0052] In one feasible implementation, see again Figure 2 and Figure 3 The fingerprint recognition circuit 1 further includes a driving module 5, which is electrically connected to the first node Q and the first voltage signal line VDD. The control module 3 includes a reading unit 6, and the control signal line cl includes a read control signal line Read. The reading unit 6 is electrically connected to the read control signal line Read, the driving module 5, and the output signal line Data. As mentioned above, the driving module 5 may include a driving transistor M0, and the reading unit 6 may include a read transistor M1.

[0053] When the read control signal provided by the read control signal line Read switches from the disabled voltage Vne to the enabled voltage Ve, the common voltage signal Vcom switches from the first voltage V1 to the second voltage V2.

[0054] Taking a value greater than Vne as an example, when the read control signal jumps from low to high, the potential of the first node Q will fluctuate positively due to the parasitic capacitance of the read transistor M1 and the drive transistor M0. This embodiment of the invention controls the common voltage signal Vcom to undergo a downward voltage jump at that moment. The negative influence of the falling edge of the common voltage signal Vcom on the potential of the first node Q can be used to offset the positive influence of the rising edge of the read control signal on the potential of the first node Q, thereby stabilizing the potential of the first node Q and preventing it from oscillating.

[0055] Furthermore, see again Figure 3 When the read control signal changes from the enable voltage Ve to the disable voltage Vne, the common voltage signal Vcom changes from the second voltage V2 to the first voltage V1.

[0056] Taking the case where Ve is greater than Vne as an example, this configuration allows, on the one hand, the common voltage signal Vcom to be pulled up to the first voltage V1 before the next rising edge of the read control signal arrives. Then, when the next rising edge of the read control signal arrives, the common voltage signal Vcom can be controlled to jump down to the second voltage V2. On the other hand, the common voltage signal Vcom remains a stable second voltage V2 during both the first read period t21 and the second read period t22. During these two periods, there are no voltage fluctuations in the common voltage signal Vcom, thus not affecting the leakage current generated by the photosensitive element 2, and consequently, not affecting the accuracy of the acquired reference voltage and detection voltage.

[0057] In one feasible implementation, such as Figure 4 and Figure 5 As shown, Figure 4 This is a schematic diagram of a circuit structure of the fingerprint recognition circuit 1 provided in an embodiment of the present invention. Figure 5 for Figure 4 In one corresponding timing diagram, control module 3 includes a reset unit 7, and control signal line cl includes a reset control signal line Rst. Reset unit 7 is electrically connected to the reset control signal line Rst, the second voltage signal line Vrst, and the first node Q. As mentioned earlier, reset unit 7 may include a reset transistor M2.

[0058] When the reset control signal provided by the reset control signal line Rst jumps from the disabled voltage Vne to the enabled voltage Ve, the common voltage signal Vcom jumps from the first voltage V1 to the second voltage V2.

[0059] Taking a value greater than Vne as an example, when the reset control signal jumps from low to high, the potential of the first node Q will fluctuate positively due to the parasitic capacitance of the reset transistor M2. This embodiment of the invention controls the common voltage signal Vcom to undergo a downward voltage jump at that moment. The negative influence of the falling edge of the common voltage signal Vcom on the potential of the first node Q can be used to offset the positive influence of the rising edge of the reset control signal on the potential of the first node Q, thereby stabilizing the potential of the first node Q and preventing it from oscillating.

[0060] In addition, in one setting, such as Figure 6 As shown, Figure 6 The schematic diagram of another circuit structure of the fingerprint recognition circuit 1 provided in this embodiment of the invention shows that the second voltage signal line Vrst and the first voltage signal line VDD can be multiplexed. In this structure, at the instant the reset transistor M2 is turned on, the first voltage signal line VDD needs to supply power to both the path where the reset transistor M2 is located and the path where the driving transistor M0 is located. This causes the voltage on the first voltage signal line VDD to fluctuate, which in turn causes the potential of the first node Q to fluctuate as well. However, by controlling the voltage of the common voltage signal Vcom to also jump, this embodiment of the invention can suppress the fluctuation of the first node Q caused by this reason to a certain extent, and further improve the stability of the potential of the first node Q.

[0061] Further, see Figure 5 When the reset control signal changes from the enable voltage Ve to the disable voltage Vne, the common voltage signal Vcom changes from the second voltage V2 to the first voltage V1.

[0062] Taking the case where Ve is greater than Vne as an example, this configuration allows, on the one hand, the common voltage signal Vcom to be pulled up to the first voltage V1 before the next rising edge of the reset control signal arrives. Then, when the next rising edge of the reset control signal arrives, the common voltage signal Vcom can be controlled to jump down to the second voltage V2. On the other hand, the common voltage signal Vcom remains a stable second voltage V2 during both the first reading period t21 and the second reading period t22. During these two periods, there are no voltage fluctuations in the common voltage signal Vcom, thus not affecting the leakage current generated by the photosensitive element 2, and consequently not affecting the accuracy of the acquired reference voltage and detection voltage.

[0063] In addition, it should be noted that Figure 2 , Figure 4 and Figure 6The illustrations all use N-type transistors as examples for the driving transistor M0, reset transistor M2, and read transistor M1. In other optional embodiments of the present invention, P-type transistors can also be used for the driving transistor M0, reset transistor M2, and read transistor M1, in which case Ve is less than Vne. Taking the control module 3 including the read unit 6 as an example, as... Figure 7 and Figure 8 As shown, Figure 7 This is a schematic diagram of another circuit structure of the fingerprint recognition circuit 1 provided in an embodiment of the present invention. Figure 8 for Figure 7 In one corresponding timing diagram, when the read control signal experiences a falling edge, the common voltage signal Vcom needs to experience a rising edge. It should be noted that when the transistor is an N-type transistor, the negative terminal of the photosensitive element 2 is electrically connected to the first node Q, and the positive terminal is electrically connected to the common voltage structure 4. When the transistor is a P-type transistor, the positive terminal of the photosensitive element 2 is electrically connected to the first node Q, and the negative terminal is electrically connected to the common voltage structure 4. However, the working principle of the fingerprint recognition circuit 1 when the transistor is P-type is similar to that when the transistor is N-type, and will not be elaborated further here.

[0064] In one feasible implementation, Ve > Vne, V2 < V1, that is, the driving transistor M0, reset transistor M2, and reading transistor M1 in the fingerprint recognition circuit 1 are all N-type transistors. At the instant that the reset transistor M2 or the reading transistor M1 is turned on, the common voltage signal Vcom generates a downward voltage jump.

[0065] Compared to P-type transistors, N-type transistors have a faster response speed, resulting in superior performance of the fingerprint recognition circuit 1, which helps to further optimize the fingerprint recognition performance of the display device.

[0066] Furthermore, V1≤0, so that during the initialization period t1, the second voltage signal line Vrst does not need to provide too high a voltage to make the potential of the first node Q after initialization higher than the potential of the common voltage signal Vcom, thereby ensuring that the photosensitive element 2 is in a stable reverse bias cutoff state and will not generate leakage current.

[0067] In one feasible implementation, in order to avoid the voltage jump of the common voltage signal Vcom being too large and affecting the stability of the reverse bias cutoff state or the state of leakage current generation of the photosensitive element 2, V1 and V2 can be made to satisfy: 0 < |V2 - V1| ≤ 1V.

[0068] In one feasible implementation, see again Figure 1The fingerprint recognition sensor includes multiple common voltage structures 4, which are spaced apart. Each common voltage structure 4 has a cutout 8, which overlaps with the photosensitive element 2 in a direction perpendicular to the plane of the fingerprint recognition sensor. Each common voltage structure 4 is electrically connected to a portion of the photosensitive element 2 of the fingerprint recognition circuit 1.

[0069] For example, such as Figure 9 As shown, Figure 9 This is a schematic diagram of a film structure for a fingerprint recognition sensor provided in an embodiment of the present invention. The photosensitive element 2 includes a first electrode 20, a second electrode 21, and a photosensitive layer 22 located between the first electrode 20 and the second electrode 21. The first electrode 20 is a metal electrode, and the second electrode 21 is a light-transmitting electrode. A common voltage structure 4 may be located on one side of the photosensitive element 2. In a direction perpendicular to the plane of the fingerprint recognition sensor, the cutout 8 of the common voltage structure 4 overlaps with the photosensitive layer 22 to avoid obstructing the transmission of detection light.

[0070] In one design of a fingerprint sensor, the common electrode layer, connected to the fingerprint recognition circuit 1 and used to provide the common voltage signal Vcom, is a full-layer electrode structure with cutouts 8. This common electrode layer is electrically connected to all the fingerprint recognition circuits 1 in the fingerprint sensor. However, with the continuous development of full-screen fingerprint recognition technology, the size of fingerprint sensors is constantly increasing. This design would result in an excessive number of fingerprint recognition circuits 1 connected to the common electrode layer, leading to an excessive load on the common electrode layer. Consequently, the common voltage signal Vcom will experience a large voltage drop during transmission, and the common voltage signal Vcom received by the fingerprint recognition circuit 1 at different locations will vary significantly. This variation will also introduce noise, resulting in inaccurate recognition.

[0071] To address this, this embodiment of the invention employs a graphical design for the common electrode layer, dividing it into multiple independent common voltage structures 4. Each common voltage structure 4 is electrically connected to only a portion of the fingerprint recognition circuits 1, thereby significantly reducing the number of fingerprint recognition circuits 1 connected to a single common voltage structure 4. Even in large-sized fingerprint recognition sensors, the common voltage structure 4 can still maintain a small load, effectively reducing the voltage drop of the common voltage signal Vcom during transmission and improving the accuracy of fingerprint recognition.

[0072] In one feasible implementation, see again Figure 1The fingerprint recognition sensor includes multiple sub-regions 9. Each sub-region 9 includes a common voltage structure 4. The common voltage structure 4 is electrically connected to the photosensitive element 2 of the fingerprint recognition circuit 1 in the sub-region 9 to reduce the connection length between the common voltage structure 4 and the photosensitive element 2 connected to it, thereby further reducing the voltage drop of the common voltage signal Vcom during transmission.

[0073] In one feasible implementation, such as Figure 10 and Figure 11 As shown, Figure 10 This is a schematic diagram of a common voltage structure 4 provided in an embodiment of the present invention. Figure 11 This is another schematic diagram of the common voltage structure 4 provided in the embodiment of the present invention. The common voltage structure 4 is a strip structure, and multiple common voltage structures 4 are arranged along the first direction x.

[0074] It should be noted that, as Figure 12 and Figure 13 As shown, Figure 12 for Figure 10 A connection diagram of the corresponding common voltage structure 4. Figure 13 for Figure 11 A connection diagram of the corresponding common voltage structure 4 is shown. The fingerprint recognition sensor 100 can be electrically connected to the printed circuit board 300 via the flip-chip film 200. The fingerprint recognition sensor 100, the flip-chip film 200, and the printed circuit board 300 are all located on the backlight side of the display panel 400. One or both ends of the common voltage structure 4 can be led to the flip-chip film 200 via the connecting wire 10 and electrically connected to the driver chip on the flip-chip film 200 to receive the common voltage signal Vcom provided by the driver chip.

[0075] In this structure, the arrangement of the common voltage structure 4 is more regular. One common voltage structure 4 is electrically connected to multiple rows or columns of fingerprint recognition circuits 1. Each common voltage structure 4 needs to drive fewer fingerprint recognition circuits 1, which can effectively reduce its load.

[0076] Furthermore, combined Figure 1 , Figure 10 and Figure 14 , Figure 14 This is another top view of the fingerprint recognition sensor provided in an embodiment of the present invention, wherein the first direction x intersects with the extension direction of the control signal line cl.

[0077] Taking the control signal line cl extending along the row direction (the first direction x is the column direction) as an example, in this embodiment of the invention, the control signal line cl scans the fingerprint recognition circuit 1 row by row. This embodiment of the invention matches the structure of the common voltage structure 4 with the scanning method of the control signal line cl on the fingerprint recognition circuit 1. During the scanning process of the control signal line cl, only one common voltage structure 4 needs to be applied to the common voltage signal Vcom at the same time, so that the common voltage structure 4 applies the common voltage signal Vcom to the photosensitive element 2 of the fingerprint recognition circuit 1 in a certain row. It is not necessary for all common voltage structures 4 to transmit the common voltage signal Vcom, which can effectively reduce power consumption.

[0078] In one feasible implementation, such as Figure 15 As shown, Figure 15 This is another schematic diagram of the common voltage structure 4 provided in the embodiment of the present invention. The common voltage structure 4 is a block structure, and multiple common voltage structures 4 are arranged in a matrix.

[0079] It should be noted that, as Figure 16 As shown, Figure 16 for Figure 15 A connection diagram of the corresponding common voltage structure 4 is shown. Each common voltage structure 4 can be led to the flip-chip film 200 and electrically connected to the driver chip on the flip-chip film 200 through the connecting line 10, so as to receive the common voltage signal Vcom provided by the driver chip.

[0080] In this structure, the arrangement of the common voltage structure 4 is more regular. One common voltage structure 4 can be electrically connected to m×n fingerprint recognition circuits 1 arranged in a matrix. The number of fingerprint recognition circuits 1 that each common voltage structure 4 needs to drive is small, which can effectively reduce its load.

[0081] Based on the same inventive concept, embodiments of the present invention also provide a driving method for a fingerprint recognition sensor, combined with Figures 1-3 The fingerprint recognition sensor includes multiple fingerprint recognition circuits 1. Each fingerprint recognition circuit 1 includes a first node Q, a photosensitive element 2, and a control module 3. The photosensitive element 2 is electrically connected to the first node Q and a common voltage structure 4 for providing a common voltage signal Vcom. The control module 3 is electrically connected to a control signal line cl. The control module 3 is used to turn on when the control signal line cl provides an enable voltage Ve. The control module 3 is also coupled to the first node Q.

[0082] The driving method includes: when the control signal provided by the control signal line cl jumps from the disabled voltage to the enabled voltage, the common voltage signal Vcom jumps from the first voltage to the second voltage, where (Ve-Vne)×(V2-V1)<0, Vne is the voltage value of the disabled voltage, Ve is the voltage value of the enabled voltage, V1 is the voltage value of the first voltage, and V2 is the voltage value of the second voltage.

[0083] As analyzed above, this embodiment of the invention employs a stepped design for the common voltage signal Vcom received by the photosensitive element 2, making it no longer a fixed voltage. Thus, when a voltage jump occurs in the control signal, the effect of the opposite-direction voltage jump generated by the common voltage signal Vcom on the Q potential of the first node can be used to counteract the effect of the control signal's voltage jump on the Q potential of the first node. Taking Ve greater than Vne as an example, see [link to relevant documentation]. Figure 3 When the control signal has a rising edge, it will positively pull the potential of the first node Q. At this time, by controlling the common voltage signal Vcom to have a falling edge, based on the parasitic capacitance of the photodiode, this falling edge can be used to negatively pull the potential of the first node Q. This negative pull can cancel out the positive pull of the rising edge of the control signal on the first node Q, thereby effectively suppressing the potential oscillation of the first node Q, improving the signal-to-noise ratio, and thus effectively improving the fingerprint recognition accuracy.

[0084] In one feasible implementation, combined with Figure 2 and Figure 3 The fingerprint recognition circuit 1 also includes a driving module 5, which is electrically connected to the first node Q and the first voltage signal line VDD.

[0085] The control module 3 includes a reading unit 6, and the control signal line cl includes a reading control signal line Read. The reading unit 6 is electrically connected to the reading control signal line Read, the drive module 5, and the output signal line Data, respectively.

[0086] When the control signal jumps from the disabled voltage Vne to the enabled voltage Ve, the common voltage signal Vcom jumps from the first voltage V1 to the second voltage V2. This process includes: when the read control signal provided by the read control signal line Read jumps from the disabled voltage Vne to the enabled voltage Ve, the common voltage signal Vcom jumps from the first voltage V1 to the second voltage V2.

[0087] Taking a value greater than Vne as an example, when the read control signal jumps from low to high, the potential of the first node Q will fluctuate positively due to the parasitic capacitance of the read transistor M1 and the drive transistor M0. This embodiment of the invention controls the common voltage signal Vcom to undergo a downward voltage jump at that moment. The negative influence of the falling edge of the common voltage signal Vcom on the potential of the first node Q can be used to offset the positive influence of the rising edge of the read control signal on the potential of the first node Q, thereby stabilizing the potential of the first node Q and preventing it from oscillating.

[0088] Furthermore, combined Figure 3 The driving method further includes: when the control signal changes from the enable voltage Ve to the disable voltage Vne, the common voltage signal Vcom changes from the second voltage V2 to the first voltage V1.

[0089] Taking the case where Ve is greater than Vne as an example, this configuration allows, on the one hand, the common voltage signal Vcom to be pulled up to the first voltage V1 before the next rising edge of the read control signal arrives. Then, when the next rising edge of the read control signal arrives, the common voltage signal Vcom can be controlled to jump down to the second voltage V2. On the other hand, the common voltage signal Vcom remains a stable second voltage V2 during both the first read period t21 and the second read period t22. During these two periods, there are no voltage fluctuations in the common voltage signal Vcom, thus not affecting the leakage current generated by the photosensitive element 2, and consequently, not affecting the accuracy of the acquired reference voltage and detection voltage.

[0090] In one feasible implementation, combined with Figure 4 and Figure 5 The control module 3 includes a reset unit 7, and the control signal line cl includes a reset control signal line Rst. The reset unit 7 is electrically connected to the reset control signal line Rst, the second voltage signal line Vrst, and the first node Q, respectively.

[0091] When the control signal transitions from the disabled voltage Vne to the enabled voltage Ve, the common voltage signal Vcom transitions from the first voltage V1 to the second voltage V2. This process includes: when the reset control signal provided by the reset control signal line Rst transitions from the disabled voltage Vne to the enabled voltage Ve, the common voltage signal Vcom transitions from the first voltage V1 to the second voltage V2.

[0092] Taking a value greater than Vne as an example, when the reset control signal jumps from low to high, the potential of the first node Q will fluctuate positively due to the parasitic capacitance of the reset transistor M2. This embodiment of the invention controls the common voltage signal Vcom to undergo a downward voltage jump at that moment. The negative influence of the falling edge of the common voltage signal Vcom on the potential of the first node Q can be used to offset the positive influence of the rising edge of the reset control signal on the potential of the first node Q, thereby stabilizing the potential of the first node Q and preventing it from oscillating.

[0093] In addition, see Figure 6 When the second voltage signal line Vrst is multiplexed with the first voltage signal line VDD, at the instant the reset transistor M2 is turned on, the first voltage signal line VDD needs to supply power to both the path where the reset transistor M2 is located and the path where the driving transistor M0 is located simultaneously. This causes voltage fluctuations on the first voltage signal line VDD, which in turn causes fluctuations in the potential of the first node Q. However, this embodiment of the invention, by controlling the voltage of the common voltage signal Vcom to also jump, can suppress the fluctuations in the first node Q caused by this reason to a certain extent, further improving the stability of the potential of the first node Q.

[0094] Furthermore, combined Figure 5 When the reset control signal changes from the enable voltage Ve to the disable voltage Vne, the common voltage signal Vcom changes from the second voltage V2 to the first voltage V1.

[0095] Taking the case where Ve is greater than Vne as an example, this configuration allows, on the one hand, the common voltage signal Vcom to be pulled up to the first voltage V1 before the next rising edge of the reset control signal arrives. Then, when the next rising edge of the reset control signal arrives, the common voltage signal Vcom can be controlled to jump down to the second voltage V2. On the other hand, the common voltage signal Vcom remains a stable second voltage V2 during both the first reading period t21 and the second reading period t22. During these two periods, there are no voltage fluctuations in the common voltage signal Vcom, thus not affecting the leakage current generated by the photosensitive element 2, and consequently not affecting the accuracy of the acquired reference voltage and detection voltage.

[0096] In one feasible implementation, Ve > Vne, V2 < V1, that is, the driving transistor M0, reset transistor M2, and reading transistor M1 in the fingerprint recognition circuit 1 are all N-type transistors. At the instant that the reset transistor M2 or the reading transistor M1 is turned on, the common voltage signal Vcom generates a downward voltage jump.

[0097] Compared to P-type transistors, N-type transistors have a faster response speed, resulting in superior performance of the fingerprint recognition circuit 1, which helps to further optimize the fingerprint recognition performance of the display device.

[0098] Furthermore, V1≤0, so that during the initialization period t1, the second voltage signal line Vrst does not need to provide too high a voltage to make the potential of the first node Q after initialization higher than the potential of the common voltage signal Vcom, thereby ensuring that the photosensitive element 2 is in a stable reverse bias cutoff state and will not generate leakage current.

[0099] In one feasible implementation, in order to avoid the voltage jump of the common voltage signal Vcom being too large and affecting the stability of the reverse bias cutoff state or the state of leakage current generation of the photosensitive element 2, V1 and V2 can be made to satisfy: 0 < |V2 - V1| ≤ 1V.

[0100] This invention also provides a display device, such as... Figure 17 As shown, Figure 17 This is a schematic diagram of a display device provided in an embodiment of the present invention. The display device includes a display panel 400 and the aforementioned fingerprint recognition sensor 100, which can be attached to the backlight side of the display panel 400. The specific structure of the fingerprint recognition sensor 100 has been described in detail in the above embodiments and will not be repeated here. Figure 17 The display device shown is for illustrative purposes only. The display device can be any electronic device with display function, such as a mobile phone, tablet computer, laptop computer, e-reader or television.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fingerprint recognition sensor, characterized in that, The device includes multiple fingerprint recognition circuits, each comprising a first node, a photosensitive element, and a control module. The photosensitive element is electrically connected to the first node and a common voltage structure, respectively. The common voltage structure is used to provide a common voltage signal. The control module is electrically connected to a control signal line and is also coupled to the first node. When the control signal provided by the control signal line jumps from a non-enable voltage to an enable voltage, the common voltage signal jumps from a first voltage to a second voltage, where (Ve-Vne)×(V2-V1)<0, Vne is the voltage value of the non-enable voltage, Ve is the voltage value of the enable voltage, V1 is the voltage value of the first voltage, and V2 is the voltage value of the second voltage. The fingerprint recognition sensor includes a plurality of common voltage structures, which are spaced apart from each other. Each common voltage structure has a cutout, and the cutout overlaps with the photosensitive element in a direction perpendicular to the plane of the fingerprint recognition sensor. Each common voltage structure is electrically connected to a portion of the photosensitive element of the fingerprint recognition circuit. The fingerprint recognition circuit further includes a driving module, which is electrically connected to the first node and the first voltage signal line respectively. The control module includes a reading unit, and the control signal line includes a reading control signal line. The reading unit is electrically connected to the reading control signal line, the driving module, and the output signal line respectively. When the reading control signal provided by the reading control signal line transitions from the disabled voltage to the enabled voltage, the common voltage signal transitions from the first voltage to the second voltage. And / or, the control module includes a reset unit, and the control signal line includes a reset control signal line. The reset unit is electrically connected to the reset control signal line, the second voltage signal line, and the first node respectively. When the reset control signal provided by the reset control signal line transitions from the disabled voltage to the enabled voltage, the common voltage signal transitions from the first voltage to the second voltage.

2. The fingerprint recognition sensor according to claim 1, characterized in that, When the read control signal changes from the enable voltage to the disable voltage, the common voltage signal changes from the second voltage to the first voltage.

3. The fingerprint recognition sensor according to claim 1, characterized in that, When the reset control signal changes from the enable voltage to the disable voltage, the common voltage signal changes from the second voltage to the first voltage.

4. The fingerprint recognition sensor according to claim 1, characterized in that, Ve > Vne, V2 < V1.

5. The fingerprint recognition sensor according to claim 4, characterized in that, V1≤0。 6. The fingerprint recognition sensor according to claim 1, characterized in that, 0 < |V2 - V1| ≤ 1V.

7. The fingerprint recognition sensor according to claim 1, characterized in that, The fingerprint recognition sensor includes multiple sub-regions, and each sub-region includes a common voltage structure, wherein the common voltage structure is electrically connected to the photosensitive element of the fingerprint recognition circuit in the sub-region.

8. The fingerprint recognition sensor according to claim 1, characterized in that, The common voltage structure is a strip structure, and multiple common voltage structures are arranged along a first direction.

9. The fingerprint recognition sensor according to claim 8, characterized in that, The first direction intersects with the extension direction of the control signal line.

10. The fingerprint recognition sensor according to claim 1, characterized in that, The common voltage structure is a block structure, and multiple common voltage structures are arranged in a matrix.

11. A driving method for a fingerprint recognition sensor, characterized in that, The fingerprint recognition sensor includes multiple fingerprint recognition circuits. Each fingerprint recognition circuit includes a first node, a photosensitive element, and a control module. The photosensitive element is electrically connected to the first node and a common voltage structure for providing a common voltage signal. The control module is electrically connected to a control signal line and is used to turn on when the control signal line provides an enable voltage. The control module is also coupled to the first node. The fingerprint recognition sensor includes multiple common voltage structures, which are spaced apart from each other. Each common voltage structure has a cutout, and the cutout overlaps with the photosensitive element in a direction perpendicular to the plane of the fingerprint recognition sensor. Each common voltage structure is electrically connected to a portion of the photosensitive element of the fingerprint recognition circuit. The driving method includes: when the control signal provided by the control signal line jumps from a disabled voltage to an enabled voltage, the common voltage signal jumps from a first voltage to a second voltage, wherein (Ve-Vne)×(V2-V1)<0, Vne is the voltage value of the disabled voltage, Ve is the voltage value of the enabled voltage, V1 is the voltage value of the first voltage, and V2 is the voltage value of the second voltage; The fingerprint recognition circuit further includes a driving module, which is electrically connected to the first node and the first voltage signal line respectively. The control module includes a reading unit, and the control signal line includes a reading control signal line. The reading unit is electrically connected to the reading control signal line, the driving module, and the output signal line respectively. When the control signal transitions from an enable voltage to an enable voltage, the process of the common voltage signal transitioning from the first voltage to the second voltage includes: when the reading control signal provided by the reading control signal line transitions from the enable voltage to the enable voltage, the common voltage signal transitions from the first voltage to the second voltage; and / or, the control module includes a reset unit, and the control signal line includes a reset control signal line. The reset unit is electrically connected to the reset control signal line, the second voltage signal line, and the first node respectively. When the control signal transitions from an enable voltage to an enable voltage, the process of the common voltage signal transitioning from the first voltage to the second voltage includes: when the reset control signal provided by the reset control signal line transitions from the enable voltage to the enable voltage, the common voltage signal transitions from the first voltage to the second voltage.

12. The driving method according to claim 11, characterized in that, The driving method further includes: when the read control signal changes from the enable voltage to the disable voltage, the common voltage signal changes from the second voltage to the first voltage.

13. The driving method according to claim 11, characterized in that, When the reset control signal changes from the enable voltage to the disable voltage, the common voltage signal changes from the second voltage to the first voltage.

14. The driving method according to claim 11, characterized in that, Ve > Vne, V2 < V1.

15. The driving method according to claim 14, characterized in that, V1≤0。 16. The driving method according to claim 11, characterized in that, 0 < |V2 - V1| ≤ 1V.

17. A display device, characterized in that, It includes a display panel and a fingerprint recognition sensor as described in any one of claims 1 to 10.

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