US-12624998-B2 - Optical sensing module, system and method for operating optical sensing system

US12624998B2US 12624998 B2US12624998 B2US 12624998B2US-12624998-B2

Abstract

The present disclosure relates to an optical sensing module, a system and a method for operating the optical sensing system. The optical sensing module includes a light emitter that emits a sensing light in a specific wavelength range and a photodiode unit. The photodiode unit includes a first photodiode used to sense a first wavelength light, a second photodiode used to sense a second wavelength light, and a third photodiode used to sense a third wavelength light. The optical sensing module implements a proximity sensor by operations of the second photodiode and the third photodiode, or a biometric sensor by operations of the first photodiode, the second photodiode, and the third photodiode. The photodiode unit receives a reflected light from an object to be detected so as to determine if the object is proximal, and then determine whether or not the proximal object is human skin.

Inventors

LAY-THANT KO
RUI-TAO ZHENG
MON-Oo Win

Assignees

LITE-ON SINGAPORE PTE. LTD.

Dates

Publication Date: 20260512
Application Date: 20231019
Priority Date: 20230601

Claims (19)

1 . An optical sensing module, comprising: a light emitter for emitting a sensing light with a spectrum covering an infrared wavelength range; and a photodiode unit, including: a first photodiode for sensing a first wavelength light, the first photodiode is connected to a first signal converter and; a second photodiode for sensing a second wavelength light, the second photodiode is connected to a second signal converter; and a third photodiode for sensing a third wavelength light, the third photodiode is connected to a third signal converter; wherein the optical sensing module implements a proximity sensor by operations of the second photodiode and the third photodiode, and the optical sensing module implements a biometric sensor by operations of the first photodiode, the second photodiode, and the third photodiode.
2 . The optical sensing module according to claim 1 , wherein the first photodiode, the second photodiode, and the third photodiode are silicon photodiodes that include filter materials for different wavelength bands.
3 . The optical sensing module according to claim 2 , wherein a sensing area of at least one of the first photodiode and the third photodiode is configured to be larger than a sensing area of the second photodiode.
4 . The optical sensing module according to claim 1 , wherein the light emitter is a wide spectrum infrared light emitter to emit the sensing light with the spectrum covering a wavelength range from 800 nm to 1100 nm.
5 . The optical sensing module according to claim 1 , wherein a wavelength of the first wavelength light is between 870 nm and 910 nm, a wavelength of the second wavelength light is between 950 nm and 990 nm, and a wavelength of the third wavelength light is between 1030 nm and 1070 nm.
6 . The optical sensing module according to claim 1 , wherein the photodiode unit further includes one or more signal-regulating circuits.
7 . An optical sensing system, comprising: a control unit; and an optical sensing module, electrically connected with the control unit, including a light emitter and a photodiode unit, wherein the photodiode unit includes a first photodiode, a second photodiode and a third photodiode; wherein the control unit drives the light emitter to emit a sensing light with a spectrum covering an infrared wavelength range and processes a sensing value generated by the photodiode unit when sensing the light reflected by an object; and the optical sensing module implements a proximity sensor by operations of the second photodiode and the third photodiode, and the optical sensing module implements a biometric sensor by operations of the first photodiode, the second photodiode, and the third photodiode.
8 . The optical sensing system according to claim 7 , wherein the first photodiode is connected to a first signal converter and used for generating a first sensing value by sensing a first wavelength light; the second photodiode is connected to a second signal converter and used for generating a second sensing value by sensing a second wavelength light; and the third photodiode is connected to a third signal converter and used for generating a third sensing value by sensing a third wavelength light; and wherein the first sensing value, the second sensing value and the third sensing value are converted into a first digital signal, a second digital signal, and a third digital signal by a first signal converter, a second signal converter and a third signal converter respectively.
9 . The optical sensing system according to claim 8 , wherein, when a sum of the second digital signal and the third digital signal is larger than or equal to a threshold, the proximity sensor determines if an object is proximal to the optical sensing module.
10 . The optical sensing system according to claim 8 , wherein, when both the first digital signal generated by the first signal converter and the third digital signal generated by the third signal converter are larger than the second digital signal generated by the second signal converter, the biometric sensor determines if a surface of an object is a human skin.
11 . The optical sensing system according to claim 8 , wherein, when a magnitude of the first digital signal is 1.1 to 2 times a magnitude of the second digital signal, and a magnitude of the third digital signal is 1.1 to 2 times the magnitude of the second digital signal, the object is determined as the human skin.
12 . A method for operating an optical sensing system, comprising: emitting a sensing light from a light emitter to an object, wherein the sensing light has a spectrum covering an infrared wavelength range; receiving a reflected sensing light by a photodiode unit, wherein the photodiode unit includes a first photodiode for sensing a first wavelength light and generating a first sensing value, a second photodiode for sensing a second wavelength light and generating a second sensing value, and a third photodiode for sensing a third wavelength light and generating three sensing values; converting the first sensing value, the second sensing value and the third sensing value into a first digital signal, a second digital signal, and a third digital signal by a first signal converter, a second signal converter and a third signal converter respectively; determining the proximity of the object by the second digital signal and the third digital signal; and determining whether or not a surface of the object is a human skin by the first digital signal, the second digital signal, and the third digital signal that are respectively converted from the three sensing values generated by the photodiode unit that implements a biometric sensor.
13 . The method according to claim 12 , wherein one or more signal-regulating circuits drives the first signal converter, the second signal converter, and the third signal converter to respectively adopt different gains.
14 . The method according to claim 12 , wherein a sensing area of at least one of the first photodiode and the third photodiode is larger than a sensing area of the second photodiode.
15 . The method according to claim 12 , wherein the first photodiode, the second photodiode, and the third photodiode are silicon photodiodes with different filter materials for different wavelength bands.
16 . The method according to claim 15 , wherein a wavelength of the first wavelength light is between 870 nm and 910 nm, a wavelength of the second wavelength light is between 950 nm and 990 nm, and a wavelength of the third wavelength light is between 1030 nm and 1070 nm.
17 . The method according to claim 12 , wherein the proximity is confirmed when a sum of second digital signal and the third digital signal is larger than a threshold.
18 . The method according to claim 12 , wherein the surface of human skin is confirmed when both the first digital signal and the third digital signal are larger than the second digital signal.
19 . The method according to claim 12 , wherein the surface of human skin is confirmed when a magnitude of the first digital signal is 1.1 to 2 times a magnitude of the second digital signal, and a magnitude of the third digital signal is 1.1 to 2 times the magnitude of the second digital signal.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION This application claims the benefit of priorities to Singapore Provisional Patent Application No. 10202260647U, filed on Dec. 30, 2022, and China Patent Application No. 202310642578.6, filed on Jun. 1, 2023 in People's Republic of China. The entire content of the above identified applications are incorporated herein by reference. Some references, which may include patents, patent applications and various publications, may be cited and discussed in the description of this disclosure. The citation and/or discussion of such references is provided merely to clarify the description of the present disclosure and is not an admission that any such reference is “prior art” to the disclosure described herein. All references cited and discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference. FIELD OF THE DISCLOSURE The present disclosure relates to an optical sensing technology, and more particularly to an optical sensing module that uses characteristics of multiple infrared wavelength bands to perform proximity detection and skin detection, a system and a method for operating the optical sensing system. BACKGROUND OF THE DISCLOSURE The conventional skin detection technology uses red (R), green (G) and blue (B) light in visible light bands to calculate among the sensing values of different color channels in the red, green and blue (RGB) color space. The reflectance ratio or the reflectance of different colors is compared, and whether human skin is detected is judged according to the reflection characteristics of the skin to these lights. Therefore, a sensor for skin detection requires a visible light source. However, each time when the sensor starts to measure the reflected lights, a user may be distracted by blinking lights, and certain power consumption is required to drive the three light emitters. Furthermore, in the conventional technology, in addition to using a red light, a green light, or an infrared light to detect changes of the human skin, the lights can also be used to measure a heart rate. However, the disadvantage of the above method is that two light emitters are required and the light sources are required to be continuously switched-on since a long period of time is needed for collecting data. Similarly, the blinking visible lights still cause distraction, and a certain power consumption for driving at least two light emitters is required. In one further conventional technology, a short-wave infrared light (SWIR) emitter having a wavelength range of from 0.9 μm to 1.7 μm, or from 0.7 μm to 2.5 μm is used as a light emitter and a sensor for detecting human skin. However, the SWIR emitter and the sensor cannot be manufactured by using a silicon wafer manufacturing technology and require an additional manufacturing process to assemble the components, thus resulting in additional costs and material consumption. SUMMARY OF THE DISCLOSURE In response to the above-referenced technical inadequacies of the conventional technologies that utilize a visible light to sense human skin and use a short-wave infrared light as a light source, the present disclosure provides an optical sensing module, an optical sensing system and a method for operating the optical sensing system for improving the above-referenced issues. The optical sensing module mainly includes a light emitter that is used to emit a sensing light with a spectrum covering an infrared wavelength range and a photodiode unit that includes a first photodiode, a second photodiode, and a third photodiode. The first photodiode is used to sense a first wavelength light and is connected with a first signal converter. The second photodiode is used to sense a second wavelength light and is connected with a second signal converter. The third photodiode is used to sense a third wavelength light and is connected with a third signal converter. In an aspect of the present disclosure, the optical sensing module implements a proximity sensor by operations of the second photodiode and the third photodiode; and the optical sensing module implements a biometric sensor by operations of the first photodiode, the second photodiode, and the third photodiode. Furthermore, the first photodiode, the second photodiode, and the third photodiode are silicon photodiodes that include filter materials for various wavelength bands. The filter materials allow the first photodiode, the second photodiode, and the third photodiode to respectively sense lights in wavelength ranges of from 870 nm to 910 nm, from 950 nm to 990 nm, and from 1030 nm to 1070 nm. Moreover, a sensing area of at least one of the first photodiode and the third photodiode is larger than the sensing area of the second photodiode, so that variations in the optical sensing module can be reduced. Preferably, the light emitter is a wide spectrum infrared light