Fingerprint sensing method, display driver fingerprint recognition circuit, and mobile device

Abstract

The present invention provides a fingerprint sensing method, a display-driven fingerprint recognition circuit, and a mobile device using the same. The fingerprint sensing method is applicable to an embedded fingerprint display panel with an optical reading array. The fingerprint sensing method includes the following steps: providing a driving polarity state of the embedded fingerprint display panel to a fingerprint reading circuit within a frame time; performing fingerprint image capture; and correcting the captured fingerprint image data based on the driving polarity state of the embedded fingerprint display panel.

Description

Technical Field

[0001] The present invention relates to a fingerprint recognition technology. More specifically, the present invention relates to a fingerprint sensing method for an embedded fingerprint display panel, a display driver fingerprint recognition circuit, and a mobile device using the same. Background Art

[0002] Fingerprint recognition technology is a biometric technology. A fingerprint recognition system is a pattern recognition system that includes modules for fingerprint image acquisition, processing, feature extraction, and comparison. It is commonly used in situations where personal identity verification is required, such as access control systems, time and attendance systems, laptops, mobile devices, internal bank processing, and bank payments. Currently, optical fingerprint recognition systems used in mobile devices are categorized as push-button and under-display. Push-button fingerprint recognition devices are typically located on the device's power button or home button, while under-display fingerprint recognition devices are typically located in a specific location below the organic light-emitting diode (OLED) panel.

[0003] Liquid crystal display panels are still the mainstream display device in mobile devices. However, structural issues of liquid crystal display panels make it difficult to configure optical fingerprint recognition on liquid crystal display panels. Summary of the Invention

[0004] The present invention aims to provide a fingerprint sensing method for an embedded fingerprint display panel, a display driver fingerprint recognition circuit, and a mobile device using the same, so as to accurately recognize a fingerprint when a finger is placed on the embedded fingerprint display panel.

[0005] In view of this, the present invention provides a fingerprint sensing method applicable to an embedded fingerprint display panel, wherein the embedded fingerprint display panel includes an optical reading array. The fingerprint sensing method includes: providing a driving polarity state of the embedded fingerprint display panel to a fingerprint reading circuit within a frame time; performing fingerprint image capture; and correcting the captured fingerprint image data based on the driving polarity state of the embedded fingerprint display panel.

[0006] The present invention further provides a display-driven fingerprint recognition circuit suitable for an embedded fingerprint display panel, wherein the embedded fingerprint display panel includes an optical reading array, and the display-driven fingerprint recognition circuit includes a display driving circuit and a fingerprint reading circuit. The display driving circuit is coupled to the embedded fingerprint display panel and drives the embedded fingerprint display panel according to display data. The fingerprint reading circuit is coupled to the optical reading array and the display driving circuit of the embedded fingerprint display panel. Within a frame time, the display driving circuit provides a driving polarity state of the embedded fingerprint display panel to the fingerprint reading circuit. The fingerprint reading circuit captures the fingerprint image through the optical reading array, and then the fingerprint reading circuit corrects the captured fingerprint image data according to the driving polarity state of the embedded fingerprint display panel.

[0007] The present invention further provides a mobile device, which includes an embedded fingerprint display panel and a display drive fingerprint recognition circuit. The embedded fingerprint display panel includes an optical reading array. The display drive fingerprint recognition circuit includes a display drive circuit and a fingerprint reading circuit. The display drive circuit is coupled to the embedded fingerprint display panel and drives the embedded fingerprint display panel according to display data. The fingerprint reading circuit is coupled to the optical reading array and the display drive circuit of the embedded fingerprint display panel. Within a frame time, the display drive circuit provides a driving polarity state of the embedded fingerprint display panel to the fingerprint reading circuit. The fingerprint reading circuit captures the fingerprint image through the optical reading array, and then the fingerprint reading circuit corrects the captured fingerprint image data according to the driving polarity state of the embedded fingerprint display panel.

[0008] According to the preferred embodiments of the present invention, a fingerprint sensing method for an embedded fingerprint display panel, a display-driven fingerprint recognition circuit, and a mobile device using the same are described. The pixel driving methods of the embedded fingerprint display panel include positive polarity driving and negative polarity driving to avoid or eliminate image sticking on the panel.

[0009] According to a preferred embodiment of the present invention, the embedded fingerprint display panel fingerprint sensing method, display driver fingerprint recognition circuit, and mobile device using the same further include a touch sensing circuit for detecting the touch position. During fingerprint recognition, the finger placement position is detected to drive the optical reading array to read the fingerprint of the finger at that position. In a preferred embodiment, before fingerprint recognition, the embedded fingerprint display driver circuit reduces the frame refresh rate of the embedded fingerprint display panel. In a preferred embodiment, the fingerprint image data is adjusted based on multiple fingerprint captures and their corresponding drive polarity states.

[0010] When the embedded fingerprint display panel is driven with positive and negative polarity, the difference in light transmittance causes noise in the fingerprint image. The spirit of this invention is to first determine the current polarity state of each pixel before capturing the fingerprint image. In this way, after the fingerprint is captured, the interference caused by polarity can be addressed by back-end image processing, significantly improving the fingerprint recognition rate.

[0011] In order to make the above and other objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 FIG2 is a schematic diagram of a module integrating an optical fingerprint and a liquid crystal display panel according to a preferred embodiment of the present invention.

[0013] Figure 2 A schematic diagram illustrating a liquid crystal driving method is shown.

[0014] Figure 3 FIG. 1 is a schematic diagram of a mobile device according to a preferred embodiment of the present invention.

[0015] Figure 4A FIG. 1 is a circuit block diagram of a display-driven fingerprint recognition circuit according to a preferred embodiment of the present invention.

[0016] Figure 4B FIG. 1 is a circuit block diagram of a display-driven fingerprint recognition circuit according to a preferred embodiment of the present invention.

[0017] Figure 4C FIG. 1 is a circuit block diagram of a display-driven fingerprint recognition circuit according to a preferred embodiment of the present invention.

[0018] Figure 5 FIG2 is a flow chart of a fingerprint sensing method for a liquid crystal display panel according to a preferred embodiment of the present invention.

[0019] Figure 6 FIG2 is a timing diagram illustrating an operation of a fingerprint sensing method for a liquid crystal display panel according to a preferred embodiment of the present invention.

[0020] Explanation of symbols:

[0021] CF: Color filter substrate

[0022] TFT: Thin Film Transistor Array (TFT array)

[0023] 300: LCD panel

[0024] 301: Display driver fingerprint recognition circuit

[0025] 401: LCD driver circuit

[0026] 402: Fingerprint reading circuit

[0027] 403: Touch sensing circuit

[0028] S501-S506: Steps of a fingerprint sensing method for a liquid crystal display panel according to a preferred embodiment of the present invention

[0029] FP: Fingerprint recognition period

[0030] TP: Touch sensing period DETAILED DESCRIPTION

[0031] Figure 1 The diagram shows a module integrating an optical fingerprint and a liquid crystal display panel according to a preferred embodiment of the present invention. In this embodiment, the panel integrating the optical fingerprint and the liquid crystal display panel can also be an embedded fingerprint display panel. Figure 1 , the liquid crystal display panel is composed of two transparent substrates (glass substrates). The upper substrate is a color filter substrate, which includes red, green, and blue (RGB) color resistance and a black matrix. The lower substrate is mainly a thin film transistor array (TFT array), which includes a metal layer, an indium tin oxide transparent electrode (ITO), a semiconductor layer (silicon), and an insulating layer (SiOx, OC...). Figure 1 In this embodiment, the upper substrate is labeled CF, the lower substrate is labeled TFT, and the liquid crystal layer LC is located between the upper and lower substrates. In this embodiment, the fingerprint image sensor (FP sensor) can be fabricated using thin-film transistor (TFT) materials and processes to produce optical sensing elements (e.g., pin diodes, pn diodes, TFTs, MIMs, etc.). Therefore, the fingerprint image sensor (FP sensor) and the liquid crystal layer LC can be fabricated simultaneously on the thin-film transistor array substrate. Furthermore, if the optical sensing element is a TFT, it can be fabricated together with the pixel switches (TFTs). In another preferred embodiment, the fingerprint image sensor (FP sensor) can also be fabricated on the color filter substrate, but this requires additional processing steps. However, the present invention does not limit the location of the FP sensor. In this embodiment, when a finger touches the panel surface for fingerprint recognition, light reflected from a backlight module, for example, is used to illuminate the finger and capture the light reflected from the fingerprint.

[0032] Figure 2 The diagram below shows the LCD driving method. Figure 2In the icon, the "+" symbol represents that the voltage of the pixel electrode is higher than the voltage of the common electrode (Vcom electrode), and the "-" symbol represents that the voltage of the pixel electrode is lower than the voltage of the common electrode. Figure 2 There are four inversion methods, namely frame inversion, line inversion, column inversion and pixel inversion. This driving method is mainly because after the liquid crystal display panel has been working for a long time, the accumulation of charge will produce the so-called image sticking. Regardless of which inversion method is used, the polarity of the pixel electrode of each pixel relative to the common electrode will be switched in adjacent frames. However, the positive / negative polarity switching of the pixel electrode not only changes the arrangement of the liquid crystal, but also directly changes the amount of light transmittance for fingerprint recognition, further causing the signal read out by the fingerprint image sensor to be unstable, affecting fingerprint recognition.

[0033] In order to solve the above problems, the following embodiments of the present invention provide a mobile device with a fingerprint recognition function on the panel. Figure 3 A schematic diagram of a mobile device according to a preferred embodiment of the present invention is shown. Figure 3 The mobile device includes a liquid crystal display panel 300 and a display-driven fingerprint recognition circuit 301. The liquid crystal display panel 300 includes an optical reading array, as described in the above embodiment, which can be used to read fingerprints.

[0034] Figure 4A FIG2 is a circuit block diagram of a display driver fingerprint recognition circuit 301 according to a preferred embodiment of the present invention. Figure 4A , this display-driven fingerprint recognition circuit 301 includes a liquid crystal display driving circuit 401, a fingerprint reading circuit 402 and a touch sensing circuit 403. The liquid crystal display driving circuit 401 is coupled to the fingerprint reading circuit 402 and the liquid crystal display panel 300, and drives the liquid crystal display panel according to a display data. The fingerprint reading circuit 402 is coupled to the optical reading array of the liquid crystal display panel 300 and the liquid crystal display driving circuit 401. The touch sensing circuit 403 is coupled to the liquid crystal display driving circuit 401 and the touch electrode of the liquid crystal display panel 300 to detect the touch position of a sensible object such as a finger or a stylus. In one embodiment, the display-driven fingerprint recognition circuit 301 may also include a liquid crystal display driving circuit 401 and a fingerprint reading circuit 402.

[0035] In another embodiment, the fingerprint reading circuit 402 may also be coupled to the touch sensing circuit 403, such as Figure 4B As shown, the touch sensing circuit 403 and the fingerprint reading circuit 402 can communicate directly. For example, when the touch sensing circuit 403 detects the touch position of a finger, it can notify the fingerprint reading circuit 402 to perform fingerprint recognition.

[0036] Furthermore, in another embodiment, the display driving circuit 401 may first provide the driving mode to the touch sensing circuit 403, and the touch sensing circuit 403 then notifies the fingerprint reading circuit 402 of the display status. Figure 4C When fingerprint recognition is required, the display driver circuit 401 notifies the touch sensing circuit 403 of the driving polarity state. The touch sensing circuit 403 then passes the driving polarity state and finger position information to the fingerprint reader circuit 402. The fingerprint reader circuit 402 can then directly perform fingerprint recognition and correct the fingerprint reading result.

[0037] Figure 5 FIG4 is a flow chart of a fingerprint sensing method for a liquid crystal display panel according to a preferred embodiment of the present invention. Figure 5 The fingerprint sensing method of the liquid crystal display panel includes the following steps:

[0038] Step S501: Start.

[0039] Step S502: Determine whether to perform fingerprint data reading. For mobile devices, such as mobile phones, fingerprint unlocking is generally required when the device is turned on. The host in the mobile phone will notify the display driver fingerprint recognition circuit 301 to perform fingerprint data reading.

[0040] Step S503: The touch sensing circuit 403 of the display driver fingerprint recognition circuit 301 detects the location of the finger touch and defines or determines the image capture range for fingerprint recognition based on this location. In this embodiment, it is assumed that the optical readout array included in the LCD panel 300 is distributed across the entire panel. In other words, fingerprint recognition can be performed at any location on the entire screen. However, in another embodiment of the present invention, if only a portion of the LCD panel 300 has the optical readout array, step S503 is not necessary and can be omitted at the designer's discretion.

[0041] Step S504: The display driver fingerprint recognition circuit 301 reduces the display data update frequency. Figure 6 , Figure 6 FIG. 1 is an operation timing diagram of a fingerprint sensing method for a liquid crystal display panel according to a preferred embodiment of the present invention. Figure 6As shown, FP stands for fingerprint recognition and TP stands for touch sensing. In this embodiment, when fingerprint recognition is activated, the original 60Hz frame rate is changed to 30Hz, and touch sensing is disabled to prevent signal interference. However, in another embodiment of the present invention, touch sensing does not necessarily need to be disabled, so disabling touch sensing is optional, and the present invention is not limited to this.

[0042] Step S505: Capture fingerprint images multiple times and make corrections according to the driving polarity. Figure 6 As shown, the display driver fingerprint recognition circuit 301 uses a time-sharing method to update the display data and perform fingerprint scanning. During the fingerprint recognition FP period, the liquid crystal display driver circuit 401 notifies the fingerprint reading circuit 402 of the driving polarity state of the frame. The fingerprint reading circuit 402 adjusts and corrects the data of the fingerprint image according to the driving polarity state. In actual applications, since the polarity of the pixel driving voltage is different, the transmittance is also different, causing the noise of fingerprint recognition to change. If the above Figure 2 For example, using column inversion, the captured fingerprint image may exhibit uneven brightness across straight lines, resulting in linear noise, or a different background value where the fingerprint is not present. However, in this embodiment of the present invention, the LCD driver circuit 401 provides the driving polarity for the fingerprint reader circuit 402 during fingerprint capture and recognition. Therefore, after the fingerprint reader circuit 402 reads the fingerprint image, it can be corrected based on the driving polarity.

[0043] The driving polarity state provided by the liquid crystal display driving circuit 401 is, for example, Figure 2 The indicated positive and negative polarity indicates the positive and negative polarity of each pixel. In another preferred embodiment of the present invention, the driving polarity state provided by the LCD driver circuit 401 may simply indicate the current LCD drive frame inversion mode, directly provide voltage data for each pixel, or provide information on whether the frame is odd or even. Therefore, the present invention does not limit the content of the driving polarity state data; any data that can inform the fingerprint reader circuit 402 of the current LCD drive polarity data falls within the scope of the present invention.

[0044] Furthermore, in step S505, multiple fingerprint image captures may be performed, and after comparing the multiple captured fingerprint recognition data, one fingerprint image may be selected for compensation and correction. Alternatively, all or part of the multiple captured fingerprint recognition data may be image processed, and the drive polarity state may be used to compensate and correct the fingerprint image. Therefore, the present invention does not limit the number of fingerprint image captures or the image processing method; any method that uses drive polarity state data to adjust the image data falls within the scope of the present invention.

[0045] Step S506: Report the adjusted fingerprint image data to the host. Once the fingerprint image correction is complete, the display driver fingerprint recognition circuit 301 transmits the adjusted fingerprint image data back to the host, completing the fingerprint sensing process. The host uses this adjusted fingerprint image data to determine whether to unlock the mobile device.

[0046] In step S503, this embodiment determines the fingerprint recognition image capture range based on the sensed touch position. In another preferred embodiment of the present invention, the fingerprint recognition image capture range can also be determined by other methods, such as operating system defaults or program defaults. Therefore, those skilled in the art can infer that the display driver fingerprint recognition circuit 301 can also determine the fingerprint image capture range based on the application timing of fingerprint recognition.

[0047] In the above embodiment, the liquid crystal display driving circuit 401 notifies the fingerprint reading circuit 402 of the driving polarity state of the frame during the fingerprint identification FP. However, in another preferred embodiment of the present invention, the fingerprint reading circuit 402 can make a request to the liquid crystal display driving circuit 401 in advance to inform the liquid crystal display driving circuit 401 that the data of the driving polarity state is currently required. Afterwards, the data of the driving polarity state of the frame is provided to the fingerprint reading circuit 402. Therefore, the present invention does not limit the time for providing the driving polarity state. In addition, although the display component in the embodiment of the present invention is illustrated by a liquid crystal display panel, it can be understood that the display component in the embedded fingerprint display panel of the present invention is not limited to the liquid crystal display panel architecture, and can also be other display components, such as organic light emitting diodes (OLEDs).

[0048] In summary, the spirit of the present invention lies in enabling the fingerprint reader circuit to determine the current polarity state of each pixel before capturing the fingerprint image. This allows for back-end image processing to address interference caused by polarity after the fingerprint is captured, significantly improving fingerprint recognition rates. Furthermore, the present invention can integrate the fingerprint recognition circuit with the display circuit, or even integrate the fingerprint recognition circuit, display circuit, and touch control circuit together, thus also being referred to as an integrated circuit or integrated fingerprint display panel.

[0049] The specific embodiments described in the detailed description of the preferred embodiments are merely for the purpose of illustrating the technical content of the present invention and are not intended to limit the present invention to these embodiments. Any modifications and variations made without departing from the spirit of the present invention and the following claims are intended to fall within the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A fingerprint sensing method, applicable to an embedded fingerprint display panel, wherein: The embedded fingerprint display panel includes an optical reading array, and the fingerprint sensing method includes: providing a driving polarity state of the embedded fingerprint display panel to a fingerprint reading circuit within a frame time; Conduct fingerprint imaging; and The captured fingerprint image data is corrected according to the driving polarity state of the embedded fingerprint display panel.

2. The fingerprint sensing method according to claim 1, wherein: The pixel driving methods of the embedded fingerprint display panel include positive polarity driving and negative polarity driving, so as to eliminate image sticking of the panel.

3. The fingerprint sensing method of claim 1 , further comprising, before performing fingerprint image capture: According to a touch position, a position for fingerprint image capture is determined.

4. The fingerprint sensing method according to claim 1 , further comprising: Before fingerprint recognition, reduce the refresh rate of the embedded fingerprint display panel.

5. The fingerprint sensing method according to claim 1 , further comprising: Before fingerprint recognition is performed, a display driving circuit is required to provide the driving polarity state of the embedded fingerprint display panel.

6. The fingerprint sensing method according to claim 1, further comprising: According to multiple fingerprint captures and their corresponding driving polarity states, the fingerprint image data is adjusted.

7. A display driver fingerprint recognition circuit, suitable for an embedded fingerprint display panel, characterized in that: The embedded fingerprint display panel includes an optical reading array, and the display driving fingerprint recognition circuit includes: a display driving circuit coupled to the embedded fingerprint display panel and driving the embedded fingerprint display panel according to display data; A fingerprint reading circuit is coupled to the optical reading array of the embedded fingerprint display panel and the display driving circuit, wherein: In one frame time, the display driving circuit provides a driving polarity state of the embedded fingerprint display panel to the fingerprint reading circuit; The fingerprint reading circuit captures the fingerprint image through the optical reading array, and then corrects the captured fingerprint image data according to the driving polarity state of the embedded fingerprint display panel.

8. The display driving fingerprint recognition circuit according to claim 7, wherein: The pixel driving mode of the embedded fingerprint display panel includes positive polarity driving and negative polarity driving. By alternating positive polarity driving and negative polarity driving, the image sticking of the panel is eliminated.

9. The display driver fingerprint recognition circuit according to claim 7, further comprising: A touch sensing circuit for detecting a touch position, When fingerprint recognition is performed, the fingerprint reading circuit determines the position of fingerprint image capture according to the touch position.

10. The display driving fingerprint recognition circuit according to claim 7, wherein: Before fingerprint recognition is performed, the embedded fingerprint display driving circuit reduces the frame refresh rate of the embedded fingerprint display panel.

11. The display driving fingerprint recognition circuit according to claim 7, wherein: Before fingerprint recognition is performed, the display driving circuit is required to provide the driving polarity state of the embedded fingerprint display panel.

12. The display driving fingerprint recognition circuit according to claim 7, wherein: According to multiple fingerprint captures and their corresponding driving polarity states, the fingerprint image data is adjusted.

13. A mobile device comprising: An embedded fingerprint display panel including an optical reading array; as well as A display driver fingerprint recognition circuit, comprising: a display driving circuit coupled to the embedded fingerprint display panel and driving the embedded fingerprint display panel according to display data; A fingerprint reading circuit is coupled to the optical reading array of the embedded fingerprint display panel and the display driving circuit, wherein: providing a driving polarity state of the embedded fingerprint display panel to the fingerprint reading circuit within a frame time; The fingerprint reading circuit captures the fingerprint image through the optical reading array, and then corrects the captured fingerprint image data according to the driving polarity state of the embedded fingerprint display panel.

14. The mobile device according to claim 13, wherein: The pixel driving mode of the embedded fingerprint display panel includes positive polarity driving and negative polarity driving. By alternating positive polarity driving and negative polarity driving, the image sticking of the panel is eliminated.

15. The mobile device of claim 13, further comprising: A touch sensing circuit for detecting a touch position, When fingerprint recognition is performed, the fingerprint reading circuit determines the position of fingerprint image capture according to the touch position.

16. The mobile device according to claim 13, wherein: Before fingerprint recognition is performed, the display driving circuit reduces the frame refresh rate of the embedded fingerprint display panel.

17. The mobile device according to claim 13, wherein: Before fingerprint recognition is performed, the display driving circuit is required to provide the driving polarity state of the embedded fingerprint display panel.

18. The mobile device according to claim 13, wherein: According to multiple fingerprint captures and their corresponding driving polarity states, the fingerprint image data is adjusted.

Images