TW202139056A - In-display optical fingerprint acquisition circuit, in-display optical fingerprint acquisition method, and information processing device capable of greatly reducing the ambient light interference signal contained in the fingerprint light signal - Google Patents

Abstract

The present invention mainly discloses an in-display optical fingerprint acquisition circuit, which comprises: a light detection unit arranged beneath a display panel, and a fingerprint acquisition module including a control unit, a pseudo-random sequence signal generation unit, and a signal decoding unit. When executing a fingerprint collection program, the present invention enables the fingerprint acquisition module to provide a pseudo-random sequence signal, so that at least one of the light-emitting units of the display panel emits a pseudo-random sequence light signal to illuminate a finger above the display panel, thereby receiving a fingerprint light signal from the finger. Since the received fingerprint light signal is also a modulated signal, the ambient light interference signal contained in the fingerprint light signal can be greatly reduced after demodulating the fingerprint light signal, and thus the subsequent fingerprint acquisition module can collect and obtain high-precision fingerprint images by excluding the interference noise from ambient light.

Description

Under-screen optical fingerprint collection circuit, under-screen optical fingerprint collection method and information processing device

The present invention relates to the technical field of display biological feature collection, in particular to an under-screen optical fingerprint collection circuit and method.

Biometric identification technology uses the inherent physiological characteristics of the human body as the basis for identification of individual organisms, such as: iris (Iris), face (Face), voice print (Voice), fingerprint (Fingerprint) and other physiological characteristics . Currently, commercially available fingerprint recognition devices are classified into optical, pressure, ultrasonic, and capacitive types. As full-screen smart phones gradually become mainstream, under-screen optical fingerprint collection and identification devices have been widely integrated into full-screen smart phones.

FIG. 1 shows an architecture diagram of a conventional smart phone including an under-screen optical fingerprint collection circuit, and FIG. 2 shows a schematic side cross-sectional view of the conventional under-screen optical fingerprint collection circuit. As shown in Figures 1 and 2, the conventional under-screen optical fingerprint collection circuit mainly includes a fingerprint collection module (chip) 1'and a photodetector integrated under the touch display screen 3'of the smart phone The array 2'uses the OLED panel or LCD backlight module of the touch display screen 3'as a light source. When performing the optical fingerprint collection process, the conventional technology makes a display panel of the touch display screen 3'display a pure color image, such as: pure white image, pure red image, pure green image, or pure red image, and then, with pure color The light 4'irradiates the finger 5'pressed on the touch display screen 3', so that the photodetector array 2'under the display panel receives a reflected light from the finger 5'. Figure 3 shows a conventional fingerprint image capture.

In the process of executing the optical fingerprint collection program, the aforementioned conventional under-screen optics including a fingerprint collection module 1', a photodetector array 2', and a light source 4'(ie, OLED panel or LCD backlight module) The fingerprint collection circuit is very susceptible to interference from external ambient light, which leads to a decrease in the accuracy of the collected fingerprint image. In view of this, Chinese invention patent number CN106128361B proposes an optical signal modulation circuit, which is used to add to the conventional under-screen optical fingerprint collection circuit, and mainly includes a control unit and a modulation unit, wherein the modulation unit is coupled At least one light-emitting element (ie, OLED element) to the OLED panel, and the control unit is used to control the modulation unit. When the optical fingerprint acquisition program is executed, the control unit controls the modulation unit to enable, so that a modulation signal is transmitted to the light-emitting element through the modulation unit, so that the light-emitting element emits a modulated light signal to irradiate the touch display screen. finger. In this way, the reflected light from the finger received by a photodetector array integrated under the touch display screen of the smart phone will also be a modulated light signal. It should be understood that after demodulating the modulated light signal and processing related signals, the fingerprint acquisition module collects and obtains a high-precision fingerprint image while eliminating interference noise from external ambient light.

Unfortunately, the modulation signal is usually a square wave, which is a periodic signal, and a frequency domain sine wave signal corresponding to the modulation signal is obtained through Fourier expansion. The frequency domain sine wave signal usually has high-order harmonics, so a low-pass filter must be used to filter out the high-order harmonics. In other words, if a square wave (that is, a modulated signal) is represented by a frequency domain, a series of higher harmonics will appear. These high-order harmonics may generate electromagnetic waves and current pulses, causing noise and errors in the surrounding circuits. In particular, the influence of high-order harmonics on signal processors such as analog-to-digital converters that require high-precision operation is very obvious.

Therefore, it can be seen from the above description that a novel under-screen optical fingerprint collection circuit is urgently needed in this field.

The main purpose of the present invention is to provide an under-screen optical fingerprint collection circuit that uses a pseudo-random sequence signal to cause at least one of the light-emitting units of a display panel to emit a pseudo-random sequence light signal as a light source to illuminate the area above the display panel A finger to receive a fingerprint light signal. Since the received fingerprint optical signal is also a modulated signal, after demodulating the fingerprint optical signal, the ambient light interference signal contained in the fingerprint optical signal can be greatly reduced, and the subsequent The high-precision fingerprint collection module can collect and obtain high-precision fingerprint images without interference from ambient light.

To achieve the above objective, the present invention proposes an embodiment of the under-screen optical fingerprint collection circuit, which uses at least one light-emitting unit included in a display panel as a light source, and includes:

A light detection unit arranged below the display panel; and

A fingerprint collection module, which includes:

A pseudo-random sequence signal generating unit having a command receiving terminal and a modulation signal transmitting terminal, and the signal transmitting terminal is coupled to the at least one light-emitting unit;

A signal decoding unit having a detection signal receiving end and a demodulation signal transmitting end, and the detection signal receiving end is coupled to the light detection unit; and

A control unit coupled to the command receiving end of the pseudo-random sequence signal generating unit and the demodulated signal transmitting end of the signal decoding unit;

Wherein, when a fingerprint acquisition program is executed, the control unit transmits a fingerprint image acquisition command to the pseudo-random sequence signal generating unit, thereby controlling the pseudo-random sequence signal generating unit to generate a pseudo-random sequence signal for transmission to at least one of the A light-emitting unit, enabling at least one of the light-emitting units to emit a pseudo-random sequence light signal as the light source to illuminate a finger located above the display panel;

Wherein, the light detection unit detects and transmits a fingerprint light signal of the finger to the signal decoding unit; after performing a signal demodulation process on the fingerprint light signal, the signal decoding unit transmits a digital signal to the control unit, and The control unit restores the digital signal to a fingerprint image.

In one embodiment, the pseudo-random sequence signal generating unit includes an n-bit linear-feedback shift register (n-bit LFSR), and n is a positive integer.

In one embodiment, the control unit has at least one fingerprint image operation function for restoring the digital signal to the fingerprint image.

In one embodiment, the light-emitting unit is selected from organic light-emitting diode (OLED), sub-millimeter light-emitting diode (Mini LED), micro-light-emitting diode (Micro LED), A light-emitting element selected by the group consisting of LCD backlight.

In one embodiment, an optical unit is further provided between the light detection unit and the display panel to assist the light detection unit to collect the fingerprint light signal.

The present invention also provides an under-screen optical fingerprint collection method, which includes the following steps:

(1) Generate and provide a pseudo-random sequence signal to at least one light-emitting unit included in a display panel according to a fingerprint image acquisition command, so as to emit a pseudo-random sequence light signal as a light source to illuminate above the display panel One finger

(2) Receive a reflected light signal from the finger, and generate a fingerprint light signal according to the reflected light signal;

(3) Perform a signal demodulation process on the fingerprint optical signal to generate a digital signal; and

(4) Restore the digital signal processing to a fingerprint image.

In one embodiment, the pseudo-random sequence signal includes a random binary sequence selected from the group consisting of m sequence, Gold sequence, M sequence, Walsh sequence, and R-s sequence.

In an embodiment, the fingerprint image acquisition command is a reference clock signal.

The present invention also provides an information processing device, which has an under-screen optical fingerprint collection chip for implementing the under-screen optical fingerprint collection method of the present invention as described above, thereby realizing a fingerprint image collection function.

In a feasible embodiment, the aforementioned information processing device of the present invention is an electronic device selected from the group consisting of a smart phone, a tablet computer, a notebook computer, an all-in-one computer, a fingerprint punching device, and an access control device. Device.

In order to enable your reviewer to further understand the structure, features, purpose, and advantages of the present invention, the drawings and detailed descriptions of preferred specific embodiments are attached as follows.

FIG. 4 is a schematic diagram of a smart phone including an under-screen optical fingerprint collection circuit of the present invention, and FIG. 5 is a schematic diagram of a schematic diagram of the under-screen optical fingerprint collection circuit of the present invention. As shown in FIGS. 4 and 5, the under-screen optical fingerprint collection circuit 1 of the present invention mainly includes a light detection unit 11 and a fingerprint collection module 12 disposed below a display panel 21, and it uses a display panel At least one light-emitting unit 211 contained in 21 serves as a light source. It is supplemented that, in a feasible embodiment, the light detection unit 11 may be a photodiode (Photodiode) array, a CMOS image sensor array, a CCD image sensor array, or an indium gallium zinc oxide thin film electrical Crystal (IGZO TFT) array. On the other hand, the light-emitting unit may be an organic light-emitting diode (OLED), a millimeter light-emitting diode (Mini LED), a micro-light-emitting diode (Micro LED), or an organic light-emitting diode (OLED). LCD backlight. In other words, the display panel 21 mounted on the smart phone 2 can be an OLED display panel, a Mini LED display panel, a Micro LED display panel, or an LCD panel.

In the under-screen optical fingerprint acquisition circuit 1 of the present invention, the fingerprint acquisition module 12 has a control unit 120, a pseudo-random sequence signal generation unit 121, and a signal decoding unit 122, wherein the pseudo-random sequence signal generation unit has a A command receiving terminal and a modulation signal transmitting terminal, and the command receiving terminal is coupled to a fingerprint image collection command transmitted by the control unit 120, and the modulation signal transmitting terminal is coupled to at least one of the light emitting devices. Unit 211. on the other hand. The signal decoding unit 122 has a detection signal receiving end and a demodulation signal transmitting end, and the detection signal receiving end is coupled to the light detection unit 11, and the demodulation signal transmitting end is coupled to the Control unit 120.

When executing a fingerprint acquisition program, the control unit 120 transmits a fingerprint image acquisition command to the pseudo-random sequence signal generating unit 121, thereby controlling the pseudo-random sequence signal generating unit 121 to generate a pseudo-random sequence signal to transmit to at least one The light-emitting unit 211 causes at least one light-emitting unit 211 to emit a pseudo-random sequence light signal as the light source to illuminate a finger located above the display panel 21. In one embodiment, the pseudo-random sequence signal generating unit 121 includes an n-bit linear-feedback shift register (n-bit LFSR), and n is a positive integer. In more detail, the m sequence is a pseudo random sequence (Pseudo Random Sequence, PRS) widely used at present, which is a random binary sequence (Pseudo Random Binary Sequence, PRBS). In addition, other random binary sequences that can be applied as the pseudo-random sequence of the present invention include Gold sequence, M sequence, Walsh sequence, and R-s sequence.

After illuminating the finger 3 located above the display panel 21 with a light source containing the pseudo-random sequence light signal, the light detection unit 11 receives a reflected light signal from the finger 3, and then correspondingly transmits A fingerprint optical signal of the fingerprint pattern of the finger 3 is sent to the signal decoding unit 122. FIG. 5 also shows that an optical unit 13, such as a microlens array or a micro-diameter fiber collimator array, is further provided between the light detection unit 11 and the display panel 21 to assist the collection station of the light detection unit 11 The fingerprint light signal. With this arrangement, after the light source irradiates the fingerprint of the finger 3, the light detection unit 11 can receive the corresponding reflected light signals from the ridge 31 and valley line 32 of the fingerprint of the finger 3, respectively.

Fig. 6A shows a spectrum diagram of a fingerprint optical signal before demodulation transmitted by the light detection unit, Fig. 6B shows a spectrum diagram of a fingerprint optical signal after demodulation transmitted by the light detection unit, and Fig. 6C shows without Spectrogram of fingerprint light signal with ambient light noise signal. As shown in FIGS. 5 and 6A, since the light source used to illuminate the finger 3 contains a pseudo-random sequence light signal, the light detection unit 11 transmits a fingerprint light signal to the signal decoding unit 122 based on the received reflected light signal. It will be a modulated light signal. It can be seen from the spectrogram of FIG. 6A that the intensity of the noise signal caused by the ambient light is much greater than the fingerprint light signal. However, after performing a signal demodulation process on the fingerprint light signal, as shown in FIG. 6B, after the signal demodulation is completed, the ambient light noise signal is greatly reduced. Therefore, as shown in FIG. 6C, after removing the ambient light noise signal, the fingerprint light signal (demodulation signal) without the ambient light noise signal can be obtained.

The present invention also provides an under-screen optical fingerprint collection method to control the operation of the under-screen optical fingerprint collection circuit as shown in FIG. 4 and FIG. 5. Fig. 7 shows a flow chart of an under-screen optical fingerprint collection method of the present invention. As shown in FIGS. 7, 4 and 5, when a fingerprint acquisition program needs to be executed, the control unit 120 sends a reference clock signal as a fingerprint image acquisition command to be transmitted to the pseudo-random sequence signal generation unit 121, As a result, the pseudo-random sequence signal generating unit 121 generates and provides a pseudo-random sequence signal to at least one light-emitting unit 211 included in a display panel 21 according to a fingerprint image acquisition command, so that the at least one light-emitting unit 211 emits a pseudo The random sequence light signal is used as a light source to illuminate a finger 3 located above the display panel 21 (step S1). Continuing, in step S2, the light detection unit 11 receives a reflected light signal from the finger 3, and generates a fingerprint light signal according to the reflected light signal and transmits it to the signal decoding unit 122.

In step S3, the signal decoding unit 122 performs a signal demodulation process on the fingerprint optical signal to generate a digital signal, and transmits the digital signal to the control unit 120. Finally, in step S4, the control unit 120 uses at least one fingerprint image operation function to restore the digital signal to a fingerprint image.

In this way, the above has completely and clearly explained an under-screen optical fingerprint collection circuit and method of the present invention; and, from the above, it can be seen that the present invention has the following advantages:

(1) The present invention discloses a fingerprint collection module including a light detection unit arranged below a display panel and a control unit, a pseudo-random sequence signal generating unit and a signal decoding unit. In particular, the design of the present invention enables the fingerprint acquisition module to provide a pseudo-random sequence signal so that at least one of the light-emitting units of the display panel emits a pseudo-random sequence light signal to illuminate a finger located above the display panel, thereby receiving the A fingerprint light signal from a finger. Since the received fingerprint optical signal is also a modulated signal, after demodulating the fingerprint optical signal, the ambient light interference signal contained in the fingerprint optical signal can be greatly reduced, and the subsequent The high-precision fingerprint collection module can collect and obtain high-precision fingerprint images without interference from ambient light.

(2) The present invention also provides an information processing device, which has an under-screen optical fingerprint collection chip including the under-screen optical fingerprint collection circuit of the present invention as described above, so as to realize a fingerprint image collection function.

(3) In a feasible embodiment, the aforementioned information processing device of the present invention is selected from the group consisting of a smart phone, a tablet computer, a notebook computer, an all-in-one computer, a fingerprint punching device, and an access control device Of an electronic device.

It must be emphasized that the foregoing disclosures in this case are preferred embodiments, and any partial changes or modifications that are derived from the technical ideas of this case and are easily inferred by those who are familiar with the art will not deviate from the patent of this case. Right category.

In summary, regardless of the purpose, means and effects of this case, it is shown that it is very different from the conventional technology, and its first invention is practical, and it does meet the patent requirements of the invention. I implore the examiner to check it out and grant the patent as soon as possible. Society is for the best prayer.

<The present invention> 1: Optical fingerprint collection circuit under the screen 11: Light detection unit 12: Fingerprint collection module 13: Optical unit 120: control unit 121: Pseudo-random sequence signal generation unit 122: signal decoding unit 2: smart phone 21: display panel 211: light-emitting unit 3: fingers 31: Ridge 32: Valley line Step S1: Generate and provide a pseudo-random sequence signal to at least one light-emitting unit included in a display panel according to a fingerprint image acquisition command, thereby emitting a pseudo-random sequence light signal as a light source to illuminate above the display panel One finger Step S2: Receive a reflected light signal from the finger, and generate a fingerprint light signal according to the reflected light signal Step S3: Perform a signal demodulation process on the fingerprint optical signal to generate a digital signal Step S4: Restore the digital signal processing to a fingerprint image

＜Acquaintances＞ 1’: Fingerprint collection module 2’: Photodetector array 3’: Touch display screen 4’: Pure color light 5’: Finger

FIG. 1 is a structural diagram of a conventional smart phone including an under-screen optical fingerprint collection circuit; FIG. 2 is a schematic diagram of the structure of a conventional under-screen optical fingerprint acquisition circuit; Figure 3 is a conventional fingerprint image collection; 4 is a structural diagram of a smart phone including an under-screen optical fingerprint collection circuit of the present invention; FIG. 5 is a schematic diagram of the architecture of the under-screen optical fingerprint collection circuit of the present invention; 6A is a spectrum diagram of a fingerprint optical signal before demodulation transmitted by an optical detection unit of the present invention; FIG. 6B is a spectrum diagram of a demodulated fingerprint optical signal transmitted by the optical detection unit of the present invention; 6C is a spectrum diagram of the fingerprint optical signal without ambient light noise signal according to the present invention; and Fig. 7 is a flowchart of an under-screen optical fingerprint collection method of the present invention.

1: Optical fingerprint collection circuit under the screen

11: Light detection unit

12: Fingerprint collection module

120: control unit

121: Pseudo-random sequence signal generation unit

122: signal decoding unit

2: smart phone

21: display panel

3: fingers

Claims (10)

An under-screen optical fingerprint collection circuit, which uses at least one light-emitting unit contained in a display panel as a light source, and includes: A light detection unit arranged below the display panel; and A fingerprint collection module, which has: A pseudo-random sequence signal generating unit having a command receiving terminal and a modulation signal transmitting terminal, and the signal transmitting terminal is coupled to the at least one light-emitting unit; A signal decoding unit having a detection signal receiving end and a demodulation signal transmitting end, and the detection signal receiving end is coupled to the light detection unit; and A control unit coupled to the command receiving end of the pseudo-random sequence signal generating unit and the demodulated signal transmitting end of the signal decoding unit; Wherein, when a fingerprint acquisition program is executed, the control unit transmits a fingerprint image acquisition command to the pseudo-random sequence signal generating unit, thereby controlling the pseudo-random sequence signal generating unit to generate a pseudo-random sequence signal for transmission to at least one of the A light-emitting unit, enabling at least one of the light-emitting units to emit a pseudo-random sequence light signal as the light source to illuminate a finger located above the display panel; Wherein, the light detection unit detects and transmits a fingerprint light signal of the finger to the signal decoding unit; after performing a signal demodulation process on the fingerprint light signal, the signal decoding unit transmits a digital signal to the control unit, and The control unit restores the digital signal to a fingerprint image. For example, the under-screen optical fingerprint acquisition circuit described in the first item of the scope of patent application, wherein the pseudo-random sequence signal generating unit includes an n-stage linear feedback shift register, and n is a positive integer. According to the under-screen optical fingerprint acquisition circuit described in the first item of the scope of patent application, the control unit has at least one fingerprint image operation function for restoring the digital signal to the fingerprint image. As described in the first item of the scope of patent application, the under-screen optical fingerprint collection circuit, wherein the light-emitting unit is selected from organic light-emitting diode (OLED), sub-millimeter light-emitting diode (Mini A light-emitting element selected by the group consisting of LED, Micro LED, and LCD backlight. For example, in the under-screen optical fingerprint collection circuit described in the first item of the scope of patent application, an optical unit is further provided between the light detection unit and the display panel to assist the light detection unit to collect the fingerprint light signal. An under-screen optical fingerprint collection method includes the following steps: Generate and provide a pseudo-random sequence signal to at least one light-emitting unit included in a display panel according to a fingerprint image acquisition command, thereby emitting a pseudo-random sequence light signal as a light source to illuminate a finger located above the display panel ； Receiving a reflected light signal from the finger, and generating a fingerprint light signal according to the reflected light signal; Perform a signal demodulation process on the fingerprint optical signal to generate a digital signal; and The digital signal processing is restored to a fingerprint image. As described in item 6 of the scope of patent application, the under-screen optical fingerprint acquisition method, wherein the pseudo-random sequence signal comprises a signal selected from the group consisting of m sequence, Gold sequence, M sequence, Walsh sequence, and Rs sequence A random binary sequence. As described in item 7 of the scope of patent application, the under-screen optical fingerprint acquisition method, wherein the fingerprint image acquisition command is a reference clock signal. An information processing device having an under-screen optical fingerprint collection chip for implementing the under-screen optical fingerprint collection method as described in any one of items 6 to 8 of the scope of patent application, thereby realizing a fingerprint image collection Function. The information processing device described in item 9 of the scope of patent application is selected from the group consisting of smart phones, tablet computers, notebook computers, all-in-one computers, fingerprint punching devices, and access control devices Electronic device.

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