Optical Transmitter and Photosensitive Apparatus

An optical transmitter includes a light source and an adjustment structure. The light source is configured to output an original light spot, to transmit a test optical signal to a skin of a user. The adjustment structure is located on an output optical path of the test optical signal. A test optical signal transmitted from an original light spot center of the original light spot is a central light spot optical signal, and the adjustment structure is configured to scatter the central light spot optical signal in a direction away from the original light spot center, to convert the original light spot

This application claims priority to Chinese Patent Application No. 202010358579.4, filed with the China National Intellectual Property Administration on Apr. 29, 2020 and entitled “OPTICAL TRANSMITTER AND PHOTOSENSITIVE APPARATUS”, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

This application relates to the field of detection technologies, and in particular, to an optical transmitter and a photosensitive apparatus.

BACKGROUND

Photoplethysmography (photoplethysmograph, PPG) is an optical measurement technology, and is widely used to measure or monitor a vital sign of a human body, for example, a heart rate (HR), a respiratory rate (RR), or oxygen saturation.FIG.1shows an existing photosensitive apparatus for which a PPG technology is used and in which a light source11and a photodetector13are disposed at an interval. The light source11is configured to transmit a test optical signal (A1 shown inFIG.1) to a skin15. Most of light is reflected inside the skin or in a skin interface (A2shown inFIG.1), and returns to the light source11. A small part of light (A3shown inFIG.1) is reflected and/or scattered inside the skin. A part of the reflected and/or scattered light (A4shown inFIG.1) returns to the photosensitive apparatus and is received by the photodetector13. This part of the reflected and/or scattered light is referred to as a backward reflected and/or scattered signal. There is maximum light intensity at a center of a light spot output by the light source11, and light intensity becomes weaker as a shifting distance from the center increases. Similarly, strength of the backward reflected and/or scattered signal also decreases as the shifting distance increases. In other words, a strength distribution curve of the test optical signal output by the light source11and a strength distribution curve of the backward reflected and/or scattered signal each are approximately in a single-bell shape. Because the photodetector13needs to be separated from the light source11by a specific distance, most test optical signals transmitted by the light source11, especially an optical signal at a center at which light intensity of a test optical signal is high and an optical signal in an adjacent region of the center, are reflected to the light source11to be consumed, and cannot be used. Consequently, the photodetector13can receive only a small quantity of effective backward reflected and/or scattered signals. In this case, utilization of the light source11is low, and power consumption of the photosensitive apparatus is high.

SUMMARY

Embodiments of this application provide an optical transmitter and a photosensitive apparatus, to improve utilization of a light source.

According to a first aspect of this application, an optical transmitter used for photoplethysmography is provided, including a light source and an adjustment structure. The light source is configured to output an original light spot, to transmit a test optical signal to a skin of a user, the adjustment structure is located on an output optical path of the test optical signal, a test optical signal transmitted from an original light spot center of the original light spot is a central light spot optical signal, and the adjustment structure is configured to scatter the central light spot optical signal in a direction away from the original light spot center, to convert the original light spot into a test light spot.

In the first aspect of this application, the adjustment structure is used to scatter the central light spot optical signal of the original light spot in the direction away from the original light spot center, to adjust a light intensity distribution of the light spot, enhance light intensity in a region outside a center of the test light spot, and improve strength of a backward signal. In other words, an original test optical signal beam transmitted by the optical transmitter is adjusted, to improve utilization of the central light spot optical signal of the original light spot, so that a photodetector can receive more effective backward signals, to reduce a loss of the optical transmitter.

According to the first aspect, in a first possible implementation of the first aspect, a light exit structure disposed on the light source is further included, and the central light spot optical signal is incident to the adjustment structure by using the light exit structure. In other words, the adjustment structure is disposed on an original output optical path of the central light spot optical signal, to change the output optical path of the central light spot optical signal. In this case, a structure of the optical transmitter is simplified.

According to the first aspect or the first to the second possible implementations of the first aspect, in a third possible implementation of the first aspect, the adjustment structure includes a grating structure, configured to diffract the incident central light spot optical signal; and/or the adjustment structure includes a reflective film, configured to reflect the incident central light spot optical signal. The original light spot can be converted into the test light spot by using a simple grating structure and/or reflective film, so that the optical transmitter maintains a simple structure when utilization of the light source is improved, to help reduce occupied space of the optical transmitter, and help miniaturize the optical transmitter.

According to the first aspect or the first to the third possible implementations of the first aspect, in a fourth possible implementation of the first aspect, the adjustment structure includes a lens structure, the lens structure includes an incident side and an emergent side, the incident side is disposed toward the light source, a recess that is concavely disposed toward a side on which the light source is located is disposed on the emergent side of the lens structure, and the central light spot optical signal is incident to the lens structure from an orthogonal projection coverage of the recess on the incident side, so that the central light spot optical signal can be effectively scattered or shifted in a direction away from the original light spot center, to improve utilization of the central light spot optical signal.

For example, the recess is a spherical surface. The central light spot optical signal is incident to the adjustment structure, and then is scattered in the direction away from the original light spot center under a scattering action of the spherical surface. For example, the recess includes a slope, and the central light spot optical signal is transmitted from another region other than the recess on the emergent side under a total internal reflection action of the slope.

According to the first aspect or the first to the fourth possible implementations of the first aspect, in a fifth possible implementation of the first aspect, the adjustment structure includes a lens structure, the lens structure includes an incident side and an emergent side, the incident side is disposed toward the light source, a recess that is concavely disposed toward a side away from the light source is disposed on the incident side of the lens structure, and the central light spot optical signal can be incident to the lens structure from the recess and be transmitted from the emergent side, so that the central light spot optical signal can be effectively scattered in a direction away from the original light spot center, to improve utilization of the central light spot optical signal.

According to the first aspect or the first to the fifth possible implementations of the first aspect, in a sixth possible implementation of the first aspect, the incident side is fastened to the light exit structure, and the lens structure directly grows on the light source, to help reduce a volume of the optical transmitter. The test optical signal transmitted by the light source directly enters the lens structure, to reduce a loss of the test optical signal in a transmission process.

According to the first aspect or the first to the sixth possible implementations of the first aspect, in a seventh possible implementation of the first aspect, the emergent side includes a spherical surface protruding in a direction away from the optical transmitter. Under a convergence action of the spherical surface, a scattering angle of the overall test optical signal is reduced.

According to the first aspect or the first to the seventh possible implementations of the first aspect, in an eighth possible implementation of the first aspect, the adjustment structure includes a light exit structure disposed on the light source, and the light exit structure is disposed by avoiding an original output optical path of the central light spot optical signal, to adjust a light intensity distribution of the light spot. The light spot can be adjusted by using a simple optical path design, to help manufacture the optical transmitter.

According to the first aspect or the first to the eighth possible implementations of the first aspect, in a ninth possible implementation of the first aspect, there are at least two light exit structures, and two adjacent light exit structures are disposed at an interval, so that the test light spot is an N-point light spot, where N is greater than 1. The original light spot can be converted into an N-point light spot by simply setting a quantity of light exit structures, to further improve convenience of manufacturing the optical transmitter.

According to the first aspect or the first to the ninth possible implementations of the first aspect, in a tenth possible implementation of the first aspect, the light exit structure is an annular structure, and the test light spot is an annular light spot. The original light spot can be converted into an annular light spot by simply setting a shape of the light exit structure, to further improve convenience of manufacturing the optical transmitter.

According to the first aspect or the first to the tenth possible implementations of the first aspect, in an eleventh possible implementation of the first aspect, the adjustment structure includes a light exit window, the light exit window includes a first connection surface, an included angle between a normal line of the first connection surface and a first direction is a first included angle, the first included angle is an acute angle, the central light spot optical signal is incident from the first connection surface to the light exit window, and the first direction is perpendicular to an original direction in which the central light spot optical signal is transmitted from the original light spot. The first connection surface changes a refraction direction of the test optical signal in the light exit window, so that a direction inclines toward a direction of the photodetector after the test optical signal is transmitted from the light exit window, to allow more effective backward signals to enter the photodetector.

According to the first aspect or the first to the eleventh possible implementations of the first aspect, in a twelfth possible implementation of the first aspect, the light exit window further includes a second connection surface disposed by being connected to the first connection surface, the first connection surface is disposed close to the photodetector, an included angle between a normal line of the second connection surface and the first direction is a second included angle, and the second included angle is greater than the first included angle.

The original light spot may be considered as a centrosymmetric light spot. The original light spot center is used as a reference. A transmission direction of an optical signal on a side that is of the original light spot and that is close to the photodetector deviates toward the photodetector, and a transmission direction of an optical signal on a side that is of the original light spot and that is away from the photodetector deviates away from the photodetector. The second included angle is greater than the first included angle, so that an adjustment degree of a test optical signal incident to the first connection surface is greater than an adjustment degree of a test optical signal incident to the second connection surface, to lead more optical signals to the photodetector, and further allow an effective backward signal to enter the photodetector.

According to the first aspect or the first to the twelfth possible implementations of the first aspect, in a thirteenth possible implementation of the first aspect, the light exit window further includes a third connection surface, the third connection surface is connected to one end that is of the first connection surface and that is away from the second connection surface, an included angle between a normal line of the third connection surface and the first direction is a third included angle, the second included angle is an acute angle, and the third included angle is an obtuse angle. The third connection surface can be used to reduce a scattering angle of a test optical signal transmitted from a part that is of the original light spot and that is close to the photodetector. In other words, edge optical signals on a side that is of the original light spot and that is close to the photodetector converge, to reduce a loss of the light source.

According to the first aspect or the first to the thirteenth possible implementations of the first aspect, in a fourteenth possible implementation of the first aspect, a light intensity distribution curve of the original light spot is a single-bell curve, there is maximum light intensity at the original light spot center, a light intensity distribution curve of the test light spot is a double-bell curve, and light intensity at a center of the test light spot is less than maximum light intensity of the test light spot, to further improve utilization of the light source of the optical transmitter.

According to the first aspect or the first to the fifteenth possible implementations of the first aspect, in a sixteenth possible implementation of the first aspect, the recess may be a spherical surface. Under a scattering action of the spherical surface, the central light spot optical signal can be effectively scattered in a direction away from the original light spot center, to improve utilization of the central light spot optical signal.

According to the first aspect or the first to the sixteenth possible implementations of the first aspect, in a seventeenth possible implementation of the first aspect, a longitudinal section of the recess is in a cone shape, to change a transmission direction of the central light spot optical signal of the original light spot, and convert the original light spot into a test light spot.

According to a second aspect, this application provides a photosensitive apparatus, including the optical transmitter and the photodetector. The photodetector is configured to receive a backward signal obtained after a test optical signal is reflected and/or scattered by a skin of a user.

An original light spot is adjusted to a test light spot by using an adjustment structure, so that a central light spot optical signal of the original light spot is shifted in a direction away from an original light spot center, to lead more test optical signals to a direction in which the photodetector is located, allow the photodetector to receive more effective backward signals, and improve detection accuracy of the photosensitive apparatus. Because utilization of the central light spot optical signal is improved, power consumption of the photosensitive apparatus is reduced.

According to the second aspect, in a first possible implementation of the second aspect, the photodetector includes a detector body and an optical receiving window, the backward signal enters the detector body through the optical receiving window, the optical receiving window includes a first surface and a second surface, the second surface is disposed toward the photodetector, and the second surface includes an inclined surface inclining toward a direction in which the optical transmitter is located, to reduce an incident angle at which a backward signal transmitted from the second surface is incident to the detector body, so that more effective backward signals enter the detector body, to further improve detection accuracy of the photosensitive apparatus.

According to the second aspect or the first possible implementation of the second aspect, in a second possible implementation of the second aspect, the photodetector includes a detector body and an optical receiving window, the backward signal enters the detector body through the optical receiving window, the detector body and the optical receiving window each are of an annular structure, and the detector body and the optical receiving window each are disposed around the optical transmitter. All backward signals at a specific distance from the center within an annular range can be received by the photodetector, to improve utilization of a light source, improve performance of the photosensitive apparatus, and reduce power consumption of the photosensitive apparatus.

DESCRIPTION OF EMBODIMENTS

FIG.2shows a device in which an example in content disclosed in this application may be implemented. A photosensitive apparatus20shown inFIG.2is a wearable device that may be worn on a wrist of a user. A PPG technology is used for the photosensitive apparatus20, and the photosensitive apparatus20is configured to measure or collect a vital sign of the user. The vital sign includes a heart rate, a respiratory rate, oxygen saturation, or the like. It can be understood that the photosensitive apparatus20is not limited to a wearable device, but may alternatively be another device that may be configured to measure or collect data of the vital sign of the user, for example, a mobile phone or a tablet computer.

Refer toFIG.3. A photosensitive apparatus20includes a processor21, a communications bus22, an analog front end (Analog Front End, AFE for short)23. a communications interface24. a memory25, an optical transmitter31, and a photodetector33. The analog front end23. the communications interface24, and the memory25each establish a communication connection with the processor21.

The analog front end23is connected to the optical transmitter31and the photodetector33. and establishes a communication connection with the processor21. The analog front end23is configured to: control generation of an optical signal of the optical transmitter31, receive a signal output by the photodetector33, convert the signal into a digital signal, and then transmit the digital signal to the processor21for processing, or convert the signal into a digital signal, perform corresponding processing (for example, digital filtering), and then transmit the digital signal to the processor21for processing.

Specifically, under control of the processor21, the analog front end23drives the optical transmitter31to transmit a test optical signal to a skin of a user. After the test optical signal irradiates the skin of the user, some test optical signals enter the skin and is reflected and/or scattered, and some reflected and/or scattered light enters the photodetector33and is received by the photodetector33. A reflected and/or scattered signal received by the photodetector33is referred to as a backward reflected and/or scattered signal, and is briefly referred to as a backward signal. The backward signal has varying intensity, and changes with a blood flow and a pulse inside a skin of a human body. The photodetector33converts the received backward signal into an electrical signal, and feeds the electrical signal back to the analog front end23, the analog front end23performs digital conversion (the analog front end23may further perform corresponding digital processing, for example, digital filtering), and feeds back or transmits, to the processor21, a digital signal obtained through conversion. The processor21is configured to perform processing and analysis on the digital signal fed back by the analog front end23, to obtain a vital sign of the user.

The processor21may be a central processing unit (Central Processing Unit, CPU), or may be another general purpose processor, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC), a field-programmable gate array (Field-Programmable Gate Array, FPGA), or another programmable logic device, discrete gate or transistor logic device, discrete hardware component, or the like. The general purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like. The processor21is a control center of the photosensitive apparatus20, and is connected to various parts of the entire photosensitive apparatus20through various interfaces and lines. The communications bus22may include a path, to transfer information between the foregoing components.

The communications interface24, by using any apparatus of a transceiver type, is configured to communicate with another device or communications network such as Ethernet, a radio access network (radio access network, RAN for short), a wireless local area network (wireless local area networks, WLAN for short), a serial peripheral interface (Serial Peripheral Interface, SPI for short), or an internal integrated circuit bus (Inter-Integrated Circuit Bus, I2C for short). The processor21and each component may have a same communications interface24or may have different communications interfaces24.

The memory25may be configured to store a computer program and/or a module. The processor21runs or executes the computer program and/or the module stored in the memory25and invokes data stored in the memory25, to implement various functions of the photosensitive apparatus20. The memory25may mainly include a program storage area and a data storage area. The program storage area may store an operating system, an application (for example, a sound playing function or an image playing function) that is required by a plurality of functions, and the like. The data storage area may store data (for example, audio data or a phone book) that is created based on use of the photosensitive apparatus20, and the like. In addition, the memory25may include a high-speed random access memory, and may further include a nonvolatile memory, for example, a hard disk, a memory, an insertion-type hard disk, a smart media card (Smart Media Card. SMC), a secure digital (Secure Digital. SD) card, a flash card (Flash Card), a plurality of magnetic storage devices, a flash memory device, or another volatile solid-state storage device. The memory25may exist independently, and is connected to the processor21through a communication connection line. Alternatively, the memory25may be integrated with the processor21. The term “and/or” describes only an association relationship for describing associated objects and represents that three relationships may exist. For example, A and/or B may represent the following three cases: Only A exists, both A and B exist, and only B exists. In addition, in the descriptions in embodiments of this application, “a plurality of” means two or more.

In a specific implementation, in an embodiment, the photosensitive apparatus20may include a plurality of processors21such as a CPU 0 and a CPU 1 inFIG.3. Each of the processors21may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. Herein, the processor may be one or more devices, circuits, and/or processing cores configured to process data (for example, computer program instructions).

In some implementations, the analog front end23may be omitted, and the processor21directly controls the optical transmitter31, and processes and analyzes the electrical signal fed back by the photodetector33. to further obtain the vital sign of the user. The optical transmitter31is configured to transmit a test optical signal to the skin of the user under control of the processor21. After the test optical signal irradiates the skin of the user, some test optical signals enter the skin and is reflected and/or scattered, and some reflected and/or scattered light enters the photodetector33and is received by the photodetector33. A reflected and/or scattered signal received by the photodetector33is referred to as a backward signal. The backward signal has varying intensity, and changes with a blood flow and a pulse inside the skin of the human body. The photodetector33converts the received backward signal into an electrical signal and feeds back the electrical signal to the processor21. The processor21is configured to perform processing and analysis on the electrical signal fed back by the photodetector33, to obtain the vital sign of the user.

The photosensitive apparatus20further includes a feedback component26. configured to send an alarm to the user when the vital sign that is of the user and that is obtained by the processor21exceeds a preset threshold, for example, when a heart rate of the user exceeds a preset heart rate. In this implementation, the feedback component26is a speaker, and the processor21controls the feedback component26to send an audio alarm It can be understood that the feedback component26may alternatively be a display, a vibrator, or the like. This is not limited herein.

In the conventional technology, a test light spot that corresponds to a test optical signal transmitted by a light source and that irradiates a skin of a user may be considered as an original light spot output by the light source. The original light spot includes an original light spot center and an edge region disposed around the original light spot center. Light intensity at the original light spot center is much greater than light intensity in the edge region. A test optical signal transmitted from the original light spot center is referred to as a central light spot optical signal. Most of test optical signals transmitted by the light source, especially the test optical signal from the original light spot center with high light intensity, are reflected by the skin back to the light source and cannot be used.

If utilization of the central light spot optical signal transmitted from the original light spot center is improved, utilization of the light source can be effectively improved, to reduce a loss of the light source. For this purpose, a photosensitive apparatus provided in Implementation 1 of this application adjusts a light intensity distribution of the original light spot, adjusts the central light spot optical signal to be scattered or shifted from the original light spot center to a direction away from the original light spot center, and leads more central light spot optical signals to the direction away from the original light spot center, so that the test light spot that is output by the light source and that irradiates the skin of the user is different from the original light spot, and a photodetector disposed around the light source can receive more effective backward signals.

Refer toFIG.4. A photosensitive apparatus30further includes a mount27and a housing28, and the mount27is fixedly accommodated inside the housing28. In this implementation, the mount27is a circuit board, and the mount27is a mainboard or a sub-board of the photosensitive apparatus20. When the mount27is the mainboard of the photosensitive apparatus20, a processor21, a communications interface24, and a memory25are fastened on the mount27. Alternatively, when the mount27is the sub-board of the photosensitive apparatus20, a processor21, a communications interface24. and a memory25are fastened on another mainboard. Alternatively, when the mount27is the sub-board of the photosensitive apparatus20, one processor21is on the sub-board, and one or more processors21, a communications interface24, and a memory25are fastened on another mainboard. It can be understood that the mount27is not limited to the circuit board. The mount27may be another supporting structure. This is not limited herein. Alternatively, the mount27may be omitted. For example, the processor21, the communications interface24, the memory25, an optical transmitter31, and a photodetector33are directly fastened to the housing28.

The housing28is provided with a first light-passing hole281and a second light-passing hole283that are disposed at an interval. The housing28is configured to protect a component such as the processor21accommodated inside the housing28.

The optical transmitter31includes a light source311and a light exit window313. The light source311is configured to output an original light spot, to transmit a test optical signal (B1 and B2 indicated inFIG.4). The light source311is provided with a light exit structure312, configured to transmit the test optical signal transmitted by the light source311. The light exit window313is located on an optical path of the test optical signal. The light exit window313is fastened inside the first light-passing hole281of the housing28. After the test optical signal sequentially passes through the light exit structure312and the light exit window313, a test light spot is formed, and then irradiates the skin of the user. The photodetector33includes a detector body331and an optical receiving window333. The detector body331is configured to receive a backward signal that is transmitted through the optical receiving window333(as shown by C1 inFIG.4). The optical receiving window313is fastened inside the second light-passing hole283.

In this implementation, the light source311is fastened on the mount27, the light source311is a light source chip, and the light exit window313and the light exit structure312are disposed at an interval. It can be understood that the light exit window313and the light exit structure312may be fastened relative to each other, or the light source311and the light exit structure312may be separated and disposed separately. It can be understood that the light source311may be a separate photo-emitting layer. In other words, no cover is required, and no light exit structure312needs to be disposed. It can be understood that a structure of the light source311is not limited. It only needs to be ensured that the light source311can transmit a test optical signal. For example, the light source311includes a photo-emitting layer and a cover3113, the photo-emitting layer is disposed at a bottom of the cover, and the light exit structure312is disposed on the cover, and is configured to transmit the test optical signal generated by the photo-emitting layer3111.

The original light spot output by the light source311may be considered as a centrosymmetric light spot. Refer toFIG.5a. In this implementation, the original light spot is approximately in a circular shape. An original light spot101includes an original light spot center1011and an edge region1013disposed around the original light spot center1011. Light intensity at the original light spot center101falls within a first light intensity range, light intensity in the edge region1013falls within a second light intensity range, and minimum light intensity in the first light intensity range is much greater than maximum light intensity in the second light intensity range. For example, the minimum light intensity in the first light intensity range and the maximum light intensity in the second light intensity range are not of a same order of magnitude, so that the original light spot center1011is obviously different from the edge region1013. A test optical signal transmitted from the original light spot center1011is a central light spot optical signal.

There is maximum light intensity at the original light spot center, and a longer distance from the original light spot center leads to weaker light intensity.FIG.5bis a schematic diagram of a light intensity distribution curve corresponding toFIG.5a. An origin 0 represents the original light spot center, a longitudinal axis represents light intensity, and a lateral axis represents a distance from the original light spot center. A light intensity distribution curve M1 of the original light spot is a single-bell curve.

Refer toFIG.6. The photosensitive apparatus20further includes a lens structure35, configured to scatter or shift the central light spot optical signal in a direction away from the original light spot center, to convert the original light spot into a test light spot. The lens structure35is disposed on the light exit structure312, and the central light spot optical signal is incident to the lens structure35by using the light exit structure312. In this implementation, the lens structure35includes a grating structure, configured to diffract the incident central light spot optical signal, so that the central light spot optical signal is scattered in a direction away from the original light spot center, to convert the original light spot into a test light spot.

In this implementation, there is one light exit structure312, and the light exit structure312is a transparent channel.

It can be understood that the lens structure35may alternatively be a reflective film, and the original light spot output by the light source311is adjusted by the lens structure35and is converted into a test light spot.

It can be understood that the light exit structure312may be a transparent hole, or the light exit structure312may be a transparent layer made of a transparent material.

Due to an adjustment function of the lens structure35, after the test optical signal transmitted by the light source311is transmitted through the light exit structure312, the test optical signal is scattered in the direction away from the original light spot center. In other words, some test optical signals are scattered from a beam center to the direction away from the beam center, to re-adjust a light intensity distribution of the light spot.FIG.7ais a schematic diagram of a light intensity distribution curve of a test light spot. A light intensity distribution curve M2 of the test light spot is a double-bell distribution curve. It can be learned that, in comparison with the original light spot, light intensity at a center of the test light spot is reduced, and light intensity of a part that is of the test light spot and that is away from the center of the test light spot is enhanced, so that the photodetector33can receive more effective backward signals, to reduce a light loss. and improve utilization of the light source311.

The lens structure35is disposed, to obtain a required test light spot. For example, referring toFIG.7b, the test light spot may be an annular light spot, the light intensity at the center of the test light spot is less than light intensity at a location around the center of the test light spot, and a darker color indicates higher light intensity inFIG.7b.

A shape of the test light spot may be different from that of the original light spot. For example, the original light spot is in a circular shape, and the test light spot is in an elliptic shape, or the like. The test light spot may be an N-point light spot (which may also be referred to as an N-center light spot), where N is greater than or equal to 2. for example, a double-point light spot (which may also be referred to as a double-center light spot as shown inFIG.7c) or a four-point light spot (which may also be referred to as a four-center light spot as shown inFIG.7d).

In another implementation, the shape of the test light spot may be adjusted by changing a quantity of light exit structures312of the optical transmitter31. In other words, an adjustment structure includes a light exit structure312. For example, referring toFIG.7eandFIG.7f, two light exit structures312are disposed at an interval in the light source311. In other words, the two adjacent light exit structures312are connected by using a non-transparent light-shielding region314. and the light-shielding regions314is located on an optical path of the central light spot optical signal, so that the central light spot optical signal is blocked and cannot be transmitted, and the test optical signal can only be transmitted from the two light exit structures312, to adjust the original light spot to a double-point light spot (also referring toFIG.7c).

In another implementation, the shape of the test light spot may be adjusted by changing a shape of the light exit structure312of the optical transmitter31. In other words, an adjustment structure includes the light exit structure312. For example, referring toFIG.7g, an annular light exit structure312is disposed around the light-shielding region314, the light-shielding region314is located on an optical path of the central light spot optical signal, the central light spot optical signal is blocked and cannot be transmitted, and the test optical signal transmitted by the light source311can only be transmitted from the annular light exit structure312, to form an annular test light spot (as shown inFIG.7b).

It can be understood that the adjustment structure includes a light exit structure disposed on the light source, and the light exit structure is disposed by avoiding an original output optical path of the central light spot optical signal.

It can be understood that there are at least two light exit structures, and the two adjacent light exit structures are disposed at an interval, so that the test light spot is an N-point light spot, where N is greater than 1.

It can be understood that the light exit structure is an annular structure, and the test light spot is an annular light spot.

It can be understood that the original light spot output by the light source311is not limited to a centrosymmetric pattern, the original light spot may alternatively be an irregular pattern, and an optical signal transmitted from a region in which light intensity of the original light spot is high (including a region with maximum light intensity) is a central light spot optical signal.

An optical transmitter provided in Implementation 2 of this application is approximately the same as the optical transmitter provided in Implementation 1. A difference lies in that an adjustment structure includes a lens structure.FIG.8atoFIG.8hare schematic diagrams of possible structures of an optical transmitter according to Implementation 2. A dashed line arrow indicates a transmission direction of a central light spot optical signal after the central light spot optical signal is transmitted from a light exit structure in a conventional photosensitive apparatus, and a solid line arrow indicates a transmission direction of a central light spot optical signal after the central light spot optical signal passes through the adjustment structure in the conventional photosensitive apparatus provided in Implementation 2.

A structure shown inFIG.8ais briefly described below. A lens structure35includes an incident side351and an emergent side353. The incident side351is disposed toward a light source311and is fastened on a light exit structure312. It can be understood that the incident side351may not be fastened on the light exit structure312, and it only needs to be ensured that there is no gap between the incident side351and the light exit structure312. A recess357that is concavely disposed toward a side on which the light source311is located is formed on the emergent side353of the lens structure35. The central light spot optical signal is incident to the lens structure35from an orthogonal projection coverage of the recess358on the incident side351, and is transmitted from the recess357. In this implementation, the emergent side353further includes a spherical surface protruding in a direction away from the light source311, to converge edge light transmitted from an edge region of an original light spot.

In this implementation, it is assumed that an output optical path on which a test optical signal is transmitted from the original light spot and does not pass through another element or component is an original output optical path. The recess357is a spherical surface that sinks toward the light source311. and a lowest point of the recess357is located on an original output optical path of a central light spot optical signal transmitted from an original light spot center.

The central light spot optical signal is incident to the lens structure35from the orthogonal projection coverage of the recess358on the incident side351, is refracted by the lens structure35, and then is transmitted from the emergent side353. Under an adjustment action of the recess357, the central light spot optical signal is scattered in a direction away from the original light spot center. The emergent side353can converge the edge light transmitted from the original light spot, to reduce a scattering angle of the entire test optical signal, so as to further help improve energy utilization of the light source of the optical transmitter.

Refer toFIG.8b. The recess357on the emergent side353may include a slope359, or the recess357may be a three-dimensional conical surface. The slope359is a projection of a three-dimensional conical surface. In other words, a longitudinal section of the recess357is in a cone shape. Based on a total internal reflection principle, a transmission direction of a test optical signal reaching the slope359is changed, to convert the original light spot into a test light spot. For example, the central light spot optical signal is incident from the incident side351to the slope359, and is transmitted, through total internal reflection of the slope359, from a remaining area on the emergent side353other than the recess357.

Refer toFIG.8c. The recess357may be disposed on the incident side351. The recess357is a spherical surface that is concavely disposed in a direction away from the light source311. An incident angle at which the central light spot optical signal is incident to the lens structure35is changed, to change a refraction direction of the central light spot optical signal in the lens structure35, so as to convert the original light spot into a test light spot.

Refer toFIG.8d. The recess357may be disposed on the incident side351, and the recess357is concavely disposed in a direction away from the optical transmitter31. The recess357includes a slope359that is disposed through connection, or the recess357may be a three-dimensional conical surface, and the slope359is a projection of the three-dimensional conical surface. In other words, the longitudinal section of the recess357is in a cone shape. The incident angle at which the test optical signal of the light source311is incident to the lens structure35is changed by using the slope359, to change the refraction direction, so as to convert the original light spot into a test light spot. For example, the central light spot optical signal is scattered in a direction away from the original light spot center after passing through the lens structure35.

A structure shown inFIG.8eis approximately the same as that shown inFIG.8a. The recess357is a spherical surface that is concavely disposed toward the light source311of the optical transmitter31. A difference lies in that the lens structure35and the light source311are disposed at an interval.

A structure shown inFIG.8fis approximately the same as that shown inFIG.8b. The recess357includes two slopes359disposed through connection, and the recess357is concavely disposed in a direction of the light source311. A difference lies in that the lens structure35and the light source311are disposed at an interval. Based on a total internal reflection principle, a transmission direction of the central light spot optical signal of the original light spot is changed, to convert the original light spot into a test light spot.

A structure shown inFIG.8gis approximately the same as that shown inFIG.8c. The recess357is disposed on the incident side351, and the recess357is a spherical surface concavely disposed in the direction away from the light source311. A difference lies in that the lens structure35and the light source311are disposed at an interval.

A structure shown inFIG.8his approximately the same as that shown inFIG.8d. The recess357is disposed on the incident side351, the recess357is a recess concavely disposed in a direction away from the light exit structure312and the light source311. and the recess357includes a slope359. A difference lies in that the lens structure35and the light source311are disposed at an interval.

It can be understood that the lens structure35of a lens type is not limited to the structures limited inFIG.8atoFIG.8h. For example, the lens structure35may be a combination of a plurality of lenses.

A photosensitive apparatus provided in Implementation 3 of this application is approximately the same as the photosensitive apparatus provided in Implementation 1. A difference lies in that an adjustment structure includes a light exit window.FIG.9atoFIG.9dare schematic diagrams of possible structures of a photosensitive apparatus according to Implementation 3. A dashed line arrow indicates a transmission direction of a central light spot optical signal after the central light spot optical signal passes through a light exit window in a conventional photosensitive apparatus, and a solid line arrow indicates a transmission direction of a central light spot optical signal after the central light spot optical signal passes through the light exit window in the photosensitive apparatus provided in Implementation 3.

Refer toFIG.9a. An optical transmitter31and a photodetector33are disposed at an interval, the light exit window313includes a first interface3131and a second interface3133that are disposed opposite to each other, and the first interface3131is disposed toward a side of a light source311. The second interface3133is a plane (a horizontal plane shown inFIG.9a), so that the second interface3133is in close contact with a skin of a user, to prevent ambient light from entering the second interface3133to cause interference.

The first interface3131is a slope. In this implementation, the first interface3131is a plane. An included angle between a normal line of the first interface3131and a first direction is a first included angle, the first included angle is an acute angle, and the first direction is perpendicular to an original direction in which the central light spot optical signal is transmitted from an original light spot. The first interface3131inclines toward a direction in which a detector body331is located. In other words, a thickness of an end that is of the light exit window313and that is close to the photodetector33is greater than a thickness of an end away from the photodetector33, to adjust an incident angle at which a test optical signal transmitted from the light source311is incident to the light exit window313, and convert the original light spot into a test light spot, so that a transmission direction of a test optical signal transmitted from the second interface3133inclines toward the direction in which the detector body331is located, and more test optical signals are led to a side on which the photodetector33is located. The first interface3131is in contact with air.

It can be understood that the first interface3131is not limited to an interface in contact with air, and the first interface3131may be in contact with the light exit structure312or the light source311without a gap, or another medium exists between the first interface3131and the light exit structure312. In only needs to be ensured that an incident angle of the central light spot optical signal can be reduced. The second interface3133is not limited to a plane. For example, the second interface3133may be a concave surface that is concavely disposed on a side that is of the light exit window313and that faces the optical transmitter31, to achieve optimal coupling with the skin of the user. Certainly, the second interface3133may alternatively be set to a convex surface that is concavely disposed toward a direction away from a side on which the optical transmitter31is located.

A test optical signal transmitted from the light exit structure312is incident to the light exit window313through the first interface3131, and then is transmitted from the second interface3133. In this implementation, a refractive index of the light exit window313is 1.4, and a refractive index of air is 1. Because the first interface3131is a slope, the test optical signal transmitted from the second interface3133is deflected and inclines from an original transmission direction to the side on which the photodetector33is located. It is equivalent to that the existing first interface that is a plane rotates clockwise by an angle θ (in other words, the normal line of the first interface that is a plane rotates clockwise by the angle θ).

The central light spot optical signal is used as an example. If the first interface remains as a conventional plane disposed extending in the first direction, the central light spot optical signal is transmitted along a normal line direction of the second interface3133(B01 shown inFIG.9a). In other words, the original light spot is approximately the same as the test light spot.

In this implementation, because the first interface3131is a slope, a central light spot optical signal of the original light spot is incident to the light exit window313after an original incident angle of 0 degrees (an angle between the central light spot optical signal and a normal line perpendicular to an incident surface) changes to an incident angle of θ, is refracted, is deflected by a deflection angle α in a rotation direction of the normal line, and then is transmitted from the second interface3133, to adjust the original light spot by using the light exit window313, to form a test light spot. A deflection angle at which the central light spot optical signal (B11 shown inFIG.9a) is deflected toward a side of the detector body331is α, so that more effective backward signals C1 can be received by the photodetector33.

Incident light at another angle rotates by an angle α in the rotation direction of the normal line (namely, in a direction of the photodetector33), and a rotation angle is related to an incident angle of a ray of light. In this manner, more test optical signals of a central light spot part and an entire light source can be reflected and/or scattered by a skin, to enter the photodetector33, so that the test optical signals are received by the detector body331.

The original light spot may be considered as a centrosymmetric light spot. The original light spot center is used as a reference. A transmission direction of a test optical signal on a side that is of the original light spot and that is close to the photodetector deviates toward the photodetector33, and a transmission direction of a test optical signal on a side that is of the original light spot and that is away from the photodetector33deviates away from the photodetector33. To lead more test optical signals to the photodetector33, the test optical signal on the side that is of the original light spot and that is away from the photodetector33may be adjusted by a greater angle.

In an implementation, referring toFIG.9b, the first interface3131includes a first connection surface3134and a second connection surface3136that are disposed through connection, and the first connection surface3134is disposed close to the detector body331. Both the first connection surface3134and the second connection surface3136are inclined surfaces inclining toward the direction in which the detector body331is located, an included angle between a normal line of the second connection surface and the first direction is a second included angle, and the second included angle is greater than the first included angle. In this implementation, the first connection surface3134and the second connection surface3136are planes, and a slope of the first connection surface3134is less than a slope of the second connection surface3136. A connection point between the first connection surface3134and the second connection surface3136is located on an original output optical path of the central light spot optical signal transmitted from the original light spot center, so that more test optical signals on the side that is of the original light spot and that is away from the photodetector33are led to the side on which the detector body331is located. The central light spot optical signal is incident from the connection point between the first connection surface3134and the second connection surface3136. However, an entire region of the first interface shown inFIG.9ais the first connection surface.

It is assumed that a test optical signal that is incident from the first connection surface3134and then is transmitted from the second interface3133is a first test optical signal D1, D01 is an original transmission direction of the first test optical signal in a conventional light exit window, in other words, a transmission direction existing when a conventional first interface corresponding to the first test optical signal is a plane disposed extending along the first direction, and a deflection angle of the first test optical signal is a first deflection angle. It is assumed that light that is incident from the second connection surface3136and then is transmitted from the second interface3133is a second test optical signal D2, D02 is an original transmission direction of the second test optical signal in the conventional light exit window, in other words, a transmission direction existing when a conventional first interface corresponding to the second test optical signal is disposed extending along the first direction, and a deflection angle of the second test optical signal is a second deflection angle. The first deflection angle is greater than the second deflection angle, so that more test optical signals on the side that is of the original light spot and that is away from the photodetector33are led to the side on which the photodetector33is located.

It can be understood that the second connection surface3136is not limited to a plane. Refer toFIG.9c. The first connection surface3134remains as an inclined plane, the second connection surface3136may be a curved surface that is concavely disposed from a side that is of the light exit window313and that faces the light source311, and the second connection surface3136is disposed approximately inclining toward the direction in which the detector body331is located, to obtain a larger deflection angle, and further help adjust, to the direction of the photodetector33, the test optical signal transmitted by the light source311.

It can be understood that, referring toFIG.9d, the first interface3131further includes a third connection surface3138, the first connection surface3134is located between the second connection surface3136and the third connection surface3138, the third connection surface3138is located on a side that is of the first connection surface3134and that is close to the photodetector33. the first connection surface3134is a slope, the second connection surface3136and the third connection surface3138each are an arc surface that is concavely disposed from a side that is of the light exit window313and that faces the light source311, and the third connection surface3138can be used to reduce a quantity of test optical signals that are transmitted from the optical transmitter, that are close to the detector body331, whose angles exceed a specific angle, and that are incident to a housing.

It can be understood that a structure of the first interface3131is not limited, and the first interface3131may be a combination of a plane, a slope, a curved surface, or another type of curved surface, to adjust an optical path, adjust more test optical signals sent by the optical transmitter31toward a side of the photodetector33, and enhance intensity of a backward signal that may be received by the photodetector33, thereby improving utilization of the light source, and improving performance of a photosensitive apparatus20.

The foregoing describes an optical path structure (which is assumed to be an X direction) along a cross section of a center of the optical transmitter and a center of the photodetector, and an optical path may be disposed in a similar manner on a cross section (a Y direction) perpendicular to a current cross section. If there is no photodetector on the cross section perpendicular to the current cross section, light transmitted by the light source may be adjusted (converged) toward a center of the light source by using two curved surfaces on the cross section perpendicular to the current cross section. This is not limited herein.

In a conventional technology, not all light reaching an optical receiving window can be received by a photodetector. When an incident angle at which a backward signal is incident to the optical receiving window is greater than a specific value, for example, when the incident backward signal is parallel to an incident surface of the optical receiving window, the backward signal cannot be received by the photodetector. In addition, a significant feature of photodetection is that a larger incident angle leads to lower photoelectric conversion efficiency. In other words, when the backward signal is perpendicularly incident to the photodetector, there is highest photoelectric conversion efficiency. Therefore, a smaller incident angle at which the backward signal is incident to the photodetector leads to more convenient receiving of the photodetector.

A photosensitive apparatus provided in Implementation 4 of this application aims to minimize, as much as possible, an incident angle at which a backward signal is incident from the optical receiving window to a detector body.

Specifically, referring toFIG.10a, a photodetector33includes a detector body331and an optical receiving window333. The optical receiving window333includes a first surface3331and a second surface3333that are disposed opposite to each other, and the second surface3333is disposed on a side that is of the optical receiving window333and that faces the detector body331.

In this implementation, the first surface3331is a plane, so that the first surface3331is in close contact with a skin of a user, to prevent ambient light from entering the first surface3331to cause interference. It can be understood that the first surface3331is not limited to a plane. For example, the first surface3331may be a concave surface that is concavely disposed in a direction of a side that is of the optical receiving window333and that faces the detector body331, to achieve optimal coupling with the skin of the user. Certainly, the first surface3331may alternatively be set as a convex surface that is concavely disposed toward a direction away from a side on which the detector body331is located.

The second surface3333is a slope, the second surface3333inclines toward the first surface3331. and a thickness of the optical receiving window333decreases from an end that is of the optical receiving window333and that is close to the optical transmitter31to an end away from the optical transmitter31. The second surface3333is configured to reduce an incident angle at which the backward signal is incident to the detector body331.

In this implementation, a refractive index of the optical receiving window333is 1.4, and a refractive index of air is 1. Because the second surface3333is a slope, a backward signal transmitted from the second surface3333approaches a normal line of the first surface3331from an original transmission direction, to further reduce the incident angle at which the backward signal is incident to the detector body331.

It is equivalent to rotate, counterclockwise by a specific angle, a first interface in which a side that is of the conventional optical receiving window and that faces the optical transmitter intersects with air. The second surface3333is set to be a slope. A backward signal C entering the optical receiving window333from the skin15of the user through the first surface3331is used as an example. An incident angle at which the backward signal C reaches the second surface3333decreases from a to a′, and then, an incident angle at which the backward signal C is incident to the detector body331decreases from θ to θ″. In this manner, the detector body331can receive more backward signals, and conversion efficiency of the photodetector33can be improved.

It can be understood that the second surface3333is not limited to be a slope, and the second surface3333may be in another shape to change an incident direction in which the backward signal is incident to the detector body331. For example, the second surface3333is a curved surface that is concavely disposed from a side that is of the optical receiving window333and that faces the photodetector33. As shown inFIG.10b, the second surface3333includes a first sub-surface3334and a second sub-surface3336that are disposed through connection, the first sub-surface3334is disposed close to the optical transmitter31, and the first sub-surface3334and the second sub-surface3336each are a curved surface. As shown inFIG.10c, the second surface3333includes a first sub-surface3334and a second sub-surface3336that are disposed through connection, and the first sub-surface3334and the second sub-surface3336each are a slope. As shown inFIG.10d, the second surface3333includes a first sub-surface3334, a second sub-surface3336, and a third sub-surface3338that are sequentially disposed through connection, the first sub-surface3334and the third sub-surface3338each are a curved surface, and the second sub-surface3336is a slope. As shown inFIG.10e, the second surface3333includes a first sub-surface3334. a second sub-surface3336, and a third sub-surface3338that are sequentially disposed through connection, the first sub-surface3334and the third sub-surface3338each are a slope, and the second sub-surface3336is a curved surface.FIG.10atoFIG.10emerely show an example shape structure of the second surface3333. The second surface3333may alternatively be any combination of a curved surface, a slope, and a curved surface.

In a conventional photosensitive setting for which a PPG technology is used, a photodetector is usually disposed on one side of a light source or a plurality of photodetectors are disposed around an optical transmitter, and processing operation space needs to be reserved between photodetectors, so that when a backward signal returns to a gap between adjacent photodetectors, the backward signal cannot be received by a photodetector.

In order that more effective backward signals can be detected, in Implementation 5 of this application, as shown inFIG.11, a photodetector33has an annular structure, an optical receiving window333has an annular structure, an optical transmitter31is located at a center of the photodetector33, and the center of the photodetector33overlaps a center of the optical receiving window333. All backward signals at a specific distance from the center within an annular range can be received by the photodetector33, to improve utilization of a light source, improve performance of a photosensitive apparatus, or reduce power consumption of a photosensitive apparatus.

It can be understood that it is not specified that the optical transmitter31is located on the center of the photodetector33. the center of the photodetector33overlaps the center of the optical receiving window333, and it only needs to be ensured that the photodetector33is disposed around the optical transmitter.

It can be understood that, in an implementation, when there is no conflict, the photosensitive apparatus may include at least one of the adjustment structures in Implementation 1 to Implementation 5. For example, the photosensitive apparatus includes an optical transmitter and a photodetector, the optical transmitter includes a light source and a light exit window, a grating and/or a reflective film are/is disposed on a light exit structure of the light source, a first connection surface is disposed on a side that is of the light exit window and that faces the light source, the photodetector includes an optical receiving window and a photodetector body, an inclined surface is disposed inclining toward the light source is disposed on a second surface that is of the optical receiving window and that faces the detector body, both the detector body and the optical receiving window are of an annular structure, and both the detector body and the optical receiving window are disposed around the optical transmitter.