CN117711037A - Screen fingerprint identification device and method based on Micro-led - Google Patents
Screen fingerprint identification device and method based on Micro-led Download PDFInfo
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- CN117711037A CN117711037A CN202311728500.2A CN202311728500A CN117711037A CN 117711037 A CN117711037 A CN 117711037A CN 202311728500 A CN202311728500 A CN 202311728500A CN 117711037 A CN117711037 A CN 117711037A
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- 238000000034 method Methods 0.000 title claims description 12
- 239000003990 capacitor Substances 0.000 claims description 12
- 238000004146 energy storage Methods 0.000 claims description 11
- 238000001514 detection method Methods 0.000 claims description 7
- 238000003825 pressing Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
Abstract
The invention mainly relates to the technical field of LED display. In order to solve the problems that an additional sensor needs to be arranged for the current Micro-led screen fingerprint identification, an additional light-to-mouth ratio is generated, and a user is required to touch a designated area for unlocking, so that the operation is not simple; the invention provides a fingerprint identification device based on a Micro-LED screen, when a fingerprint identification function is needed, a touch sensing module confirms the pressing position of a finger, a first LED chip below the finger is used as a light source for fingerprint identification, a pixel driving circuit connected with a second LED chip measures the voltage difference of photocurrent generated on the second LED chip by light rays emitted by the first LED chip through reflected light of the convex and concave positions of the fingerprint, and the shape of the fingerprint is determined; and the fingerprint identification function is completed, and the Micro-led screen is restored to a normal display state.
Description
Technical Field
The invention mainly relates to the technical field of LED display, in particular to a Micro-LED-based screen fingerprint identification device and method.
Background
Micro light emitting diode (Micro-LED) displays have been one of the important development directions of displays, which have the advantages of fast response, high resolution, high contrast, and the like. In addition to the display function, micro-LEDs may also be used as fingerprint sensors, since they may be used as photodetectors to sense the intensity of incident light, as the reverse current of the LEDs is affected by the incident light. The fingerprint recognition function has been widely used in the case of a mobile phone screen, etc., however, the existing fingerprint recognition schemes all require an additional sensor to recognize a fingerprint, and a user must touch a predetermined small area to which the sensor is attached.
In addition, the transistors in the Micro-LED driving circuit need to be compensated because the threshold voltage deviation generated by the production process can have a negative effect on the display effect. Typical compensation methods require six or more transistors, and the resulting reduction in the optical port ratio is difficult to avoid.
Disclosure of Invention
The invention aims to solve the technical problems
The utility model provides a screen fingerprint identification device based on Micro-led, solves the current screen fingerprint identification of Micro-led and need set up extra sensor, problem that the aperture ratio reduces to and need the user to touch the regional unblock of appointed, the inconvenient problem of operation.
The invention solves the technical problems
A screen fingerprint identification device based on Micro-led comprises a touch sensing detection module, a control chip and a plurality of pixel driving circuits; the pixel driving circuits are the same as the LED chips forming the Micro-LED screen in number, and each pixel driving circuit is connected with the cathode of one LED chip respectively;
the touch sensing detection module is used for detecting a position on the Micro-LED screen for fingerprint identification, the LED chip at the fingerprint identification position is a first LED chip, and the first LED chip is used for interrupting image display and emitting light according to set brightness and is used as a light source for fingerprint detection;
the pixel driving circuit is used for detecting photocurrent generated when light rays emitted by the first LED chip are reflected to the second LED chip through fingerprints;
the control chip determines a fingerprint shape according to a voltage difference of photocurrents generated on the second LED chip detected by the pixel driving circuit.
Further, the pixel driving circuit comprises a switching circuit and a driving MOS tube, a source electrode of the driving MOS tube is connected with a cathode of the LED chip, an anode of the LED chip is connected with an anode of the LED chip power supply, a drain electrode of the driving MOS tube is connected with a cathode of the LED chip power supply, and the switching circuit is used for controlling on-off of the driving MOS tube.
Further, the switching circuit comprises a first switching MOS tube, a second switching MOS tube, a third switching MOS tube and an energy storage capacitor;
the source electrode of the first switch MOS tube is connected with the grid electrode of the driving MOS tube and the energy storage capacitor, the other end of the energy storage capacitor is connected with the source electrode of the driving MOS tube, the source electrode of the driving MOS tube is simultaneously connected with the drain electrodes of the second switch MOS tube and the third switch MOS tube, the source electrode of the second switch MOS tube is connected with the control chip, and the source electrode of the third switch MOS tube is connected with the anode of the second LED chip.
Further, the fingerprint identification device also comprises a mode control chip for controlling the first LED chip to interrupt image display, and emit light according to the set brightness to serve as a light source for fingerprint identification.
The invention further provides a screen fingerprint identification method based on the Micro-led, which specifically comprises the following steps:
the touch sensing module detects the position of an LED chip shielded by a user finger on a Micro-LED screen, and the LED chip at the corresponding position is a first LED chip;
the mode control chip controls the first LED chip to interrupt image display, and emits light according to the set brightness to serve as a light source for fingerprint identification;
the first LED module is used as light rays emitted by a light source to reflect to the second LED module, and a pixel driving circuit connected with the second LED module detects that the second LED module generates photocurrent;
the control chip determines the fingerprint shape according to the voltage difference, compares the fingerprint shape with the pre-stored fingerprint shape, and judges whether to unlock the equipment.
Further, the detecting, by the pixel driving circuit connected to the second LED module, that the second LED module generates the photocurrent specifically includes: the control chip inputs preset voltage to the data voltage end of the pixel driving circuit, controls the driving MOS tube to be closed, and the current generated by the second LED chip is output from the pixel driving circuit.
Further, the method further comprises: when the LED displays images, the MOS transistor conduction control chip is controlled to be driven to input image data voltage containing MOS transistor threshold voltage compensation to the data voltage end of the pixel driving circuit.
Further, the method further comprises: after fingerprint identification is finished, the anode voltage of the LED is controlled to be initialized, and the graph display is restored.
The beneficial effects of the invention are that
According to the Micro-LED based screen fingerprint identification device, the pixel driving circuit is arranged for each LED chip forming the Micro-LED screen, so that image display and fingerprint identification can be respectively carried out in different voltage states, and an additional sensor module is not required to be added; the number of transistors required by the pixel driving circuit is only 4, so that the number of transistors is reduced, and the effect of saving the manufacturing cost can be achieved.
The Micro-led based screen fingerprint identification device is further provided with the touch sensing module, the touch sensing module is connected with the control chip and used for detecting the position of the Micro-led on the screen for fingerprint identification, a user can freely select the position of fingerprint identification when carrying out fingerprint identification, fingerprint identification is not required to be carried out on the appointed position, and the convenience of use of the user can be improved.
Drawings
FIG. 1 is a flow chart of a method of a fingerprint recognition device for Micro-led screen according to the present invention;
FIG. 2 is a schematic diagram of a fingerprint recognition device for Micro-led screen according to the present invention;
FIG. 3 is a diagram of a pixel driving circuit of a fingerprint recognition device for Micro-led screen according to the present invention;
FIG. 4 is a timing chart of control signals of a fingerprint recognition device for Micro-led screen according to the present invention;
reference numerals: m1-first switch MOS tube, M2-driving MOS tube, M3-second switch MOS tube, M4-third switch MOS tube, C S -energy storage capacitor, PD-LED chip, C LED -LED capacitance.
Detailed Description
According to the fingerprint identification device based on the Micro-LED screen, a pixel driving circuit is arranged for each LED chip forming the Micro-LED screen, and the Micro-LED screen is used as a display device to normally display images in a normal state. As shown in fig. 1: when the fingerprint identification function is needed, the touch sensing module confirms the pressing position of the finger, and the finger can block the light from the LED chip when placed on the display screen, so that the LED chip below the finger does not need to emit the light related to image data, and can be used as a light source for fingerprint identification, namely a first LED chip, a second LED chip generates photocurrent according to the reflected light generated from the convex or concave part of the finger, a pixel driving circuit connected with the second LED chip measures the voltage difference of the photocurrent generated on the second LED chip by the reflected light generated by the convex and concave part of the fingerprint, and the shape of the fingerprint is determined; and the fingerprint identification function is completed, and the Micro-led screen is restored to a normal display state.
Examples:
fig. 2 is a schematic diagram of a fingerprint identification design. When the Micro-LED screen is in a fingerprint identification state, the mode control chip controls the green LED chip covered by the fingerprint to emit light as the first LED chip, the emitted light is received by the red LED as the second LED chip after being reflected by the convex and concave parts of the fingerprint, and the photoelectric current generated by the second LED chip is acquired and processed by the control chip through the pixel driving circuit.
The pixel driving circuit is shown in fig. 3 and comprises a switching circuit and a driving MOS tube M2, wherein the source electrode of the driving MOS tube M2 is connected with the cathode of the LED chip, the anode of the LED chip is connected with the anode of the LED chip power supply, the drain electrode of the driving MOS tube M2 is connected with the cathode of the LED chip power supply, and the switching circuit is used for controlling the on-off of the driving MOS tube M2. The switching circuit comprises a first switching MOS tube, a second switching MOS tube M3, a third switching MOS tube M4 and an energy storage capacitor; the source electrode of the first switch MOS tube is connected with the grid electrode of the driving MOS tube M2 and the energy storage capacitor, the other end of the energy storage capacitor is connected with the source electrode of the driving MOS tube M2, the source electrode of the driving MOS tube M2 is simultaneously connected with the drain electrodes of the second switch MOS tube M3 and the third switch MOS tube M4, the source electrode of the second switch MOS tube M3 is connected with the control chip, and the source electrode of the third switch MOS tube M4 is connected with the cathode of the second LED chip.
V DD 、V SS 、V F And V DATA The power supply positive electrode of the LED chip, the power supply negative electrode of the LED chip, the grid control voltage of the first switch transistor and the first switch MOS transistor M1 and the image data voltage of the LED chip are respectively adopted. In the present embodiment, V DD 、V SS 、V F Set to 5V,0V and-3V, respectively. V (V) G 、V S The gate voltage and the source voltage of the MOS transistor M2 are respectively driven by the driving transistor. Energy storage capacitor C S And LED capacitance C LED 500fF and 30pF, respectively.
FIG. 4 is a timing chart of control signals of the pixel driving circuit, S 1 [n]、S 2 [n]、S 3 [n]The first switch MOS tube M1, the second switch MOS tube M3 and the third switch MOS tube M4 are respectively control signals, and the voltage range is-7 to 7V. Stages (1) (2) (3) (4) are one control cycle. In stage (1), S 1 [n]And S is 2 [n]At a high level, S 3 [n]At low level, the first switch MOS tube M1 and the second switch MOS tube M3 are conducted at the moment, the third switch MOS tube M4 is closed, the gate source voltage of the driving MOS tube M2 is a preset value, and V S Greater than V G The driving MOS transistor M2 is closed. In stage (2), S 1 [n]At low level, S 2 [n]、S 3 [n]At the high level, the first switch MOS tube M1 and the driving MOS tube M2 are closed, the second switch MOS tube M3 and the third switch MOS tube M4 are conducted, and the anode voltage of the second LED chip is initialized.
When the LED displays normally, in stage (3), S 1 [n]And S is 2 [n]At a high level, S 3 [n]At the low level, the first switch MOS tube M1 and the second switch MOS tube M3 are turned on, and the third switch MOS tube M4 is turned off. V (V) DATA Resetting the gate-source voltage of the driving MOS transistor M2 for the image data voltage including transistor threshold voltage compensation, so that the driving MOS transistor M2 is conducted; in stage (4), S 1 [n]、S 2 [n]At low level, S 3 [n]At high level, the first switch MOS tube M1 and the second switch MOS tube M3 are closed, the driving MOS tube M2 and the third switch MOS tube M4 are conducted, because of C LED Far above V S Parasitic capacitance of node, V S And (4) rapidly reducing in the beginning of the stage, and enabling the current of the second LED chip to be matched with the current determined by the gate and source voltages of the driving MOS tube M2 along with the conduction increase of the driving MOS tube M2 so as to achieve the target brightness.
When the LED performs fingerprint detection, the on-off state of the first switch MOS tube M1, the second switch MOS tube M3 and the third switch MOS tube M4 is the same as that of normal display, and in the stage (3), the gate and source voltages of the driving MOS tube M2 are set to enable the driving MOS tube M2 to be closed; in stage (4), the driving MOS tube M2 remains closed, V S The voltage increases along with the generation of photocurrent of the second LED chip; in the stage (1) of the second control period, the gate-source voltage of the driving MOS tube M2 is restored to a preset value, and in the stage (2) of the second control period, due to C ST Is floated and LED capacitor C LED Very large, V S Almost the same as the final anode voltage of the LED in the previous period (4), the accumulated charge caused by the photocurrent passes through the data voltage terminal V DATA Is read. In this embodiment, the difference between the photovoltage generated at the convex and concave portions of the skin reaches 3.5V, which can be accurately identified. After finishing fingerprint identificationAnd (3) entering a control period stage (1), controlling the anode voltage of the second LED chip to initialize, and restoring the graph display.
Claims (8)
1. The screen fingerprint identification device based on Micro-led is characterized by comprising a touch sensing detection module, a control chip and a plurality of pixel driving circuits; the pixel driving circuits are the same as the LED chips forming the Micro-LED screen in number, and each pixel driving circuit is connected with the anode of one LED chip respectively;
the touch sensing detection module is used for detecting a position on the Micro-LED screen for fingerprint identification, the LED chip at the fingerprint identification position is a first LED chip, and the first LED chip is used for interrupting image display and emitting light according to set brightness and is used as a light source for fingerprint detection;
the pixel driving circuit is used for detecting photocurrent generated when light rays emitted by the first LED chip are reflected to the second LED chip through fingerprints;
the control chip determines a fingerprint shape according to a voltage difference of photocurrents generated on the second LED chip detected by the pixel driving circuit.
2. The Micro-LED based screen fingerprint identification device according to claim 1, wherein the pixel driving circuit comprises a switching circuit and a driving MOS tube, a source electrode of the driving MOS tube is connected with an anode of the LED chip, a cathode of the LED chip is connected with a cathode of a power supply of the LED chip, a drain electrode of the driving MOS tube is connected with a cathode of the power supply of the LED chip, and the switching circuit is used for controlling on-off of the driving MOS tube.
3. The Micro-led based screen fingerprint identification device according to claim 2, wherein the switching circuit comprises a first switching MOS tube, a second switching MOS tube, a third switching MOS tube and an energy storage capacitor;
the source electrode of the first switch MOS tube is connected with the grid electrode of the driving MOS tube and the energy storage capacitor, the other end of the energy storage capacitor is connected with the source electrode of the driving MOS tube, the source electrode of the driving MOS tube is simultaneously connected with the drain electrodes of the second switch MOS tube and the third switch MOS tube, the source electrode of the second switch MOS tube is connected with the control chip, and the source electrode of the third switch MOS tube is connected with the anode of the second LED chip.
4. A Micro-LED based screen fingerprint recognition device according to any one of claims 1-3, further comprising a mode control chip for controlling the first LED chip to interrupt image display, emit light according to a set brightness, and serve as a light source for fingerprint recognition.
5. A Micro-led based screen fingerprint identification method applied to the Micro-led based screen fingerprint identification device according to any one of claims 1 to 4, comprising:
the touch sensing module detects the position of an LED chip shielded by a user finger on a Micro-LED screen, and the LED chip at the corresponding position is a first LED chip;
the mode control chip controls the first LED chip to interrupt image display, and emits light according to the set brightness to serve as a light source for fingerprint identification;
the first LED module is used as light rays emitted by a light source to reflect to the second LED module, and a pixel driving circuit connected with the second LED module detects that the second LED module generates photocurrent;
the control chip determines the fingerprint shape according to the voltage difference, compares the fingerprint shape with the pre-stored fingerprint shape, and judges whether to unlock the equipment.
6. The Micro-LED based screen fingerprint recognition method according to claim 5, wherein the detecting the photocurrent generated by the second LED module by the pixel driving circuit connected to the second LED module specifically comprises: the control chip inputs preset voltage to the data voltage end of the pixel driving circuit, controls the driving MOS tube to be closed, and the current generated by the second LED chip is output from the pixel driving circuit.
7. The Micro-led based screen fingerprint recognition method according to claim 5, further comprising: when the LED displays images, the MOS transistor conduction control chip is controlled to be driven to input image data voltage containing MOS transistor threshold voltage compensation to the data voltage end of the pixel driving circuit.
8. The Micro-led based screen fingerprint recognition method according to claim 5, further comprising: and after the fingerprint identification is finished, controlling the anode voltage of the second LED chip to initialize, and restoring the graph display.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311728500.2A CN117711037A (en) | 2023-12-15 | 2023-12-15 | Screen fingerprint identification device and method based on Micro-led |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311728500.2A CN117711037A (en) | 2023-12-15 | 2023-12-15 | Screen fingerprint identification device and method based on Micro-led |
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| Publication Number | Publication Date |
|---|---|
| CN117711037A true CN117711037A (en) | 2024-03-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311728500.2A Pending CN117711037A (en) | 2023-12-15 | 2023-12-15 | Screen fingerprint identification device and method based on Micro-led |
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| Country | Link |
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| CN (1) | CN117711037A (en) |
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- 2023-12-15 CN CN202311728500.2A patent/CN117711037A/en active Pending
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