High-precision near-field infrared sensor with modulated emission

Abstract

FIELD: scanning.SUBSTANCE: near-field modulated radiation sensor comprises at least one processor and n scanning modules connected to at least one processor, wherein each scanning module is a multi-channel phase range finder comprising a signal generator, a voltage source, a microcontroller, signal processing channels, a transmitter and a receiving group of one or two receivers, the transmitter and the receiving group are located in the working plane of the sensor, wherein the transmitter comprises an emitter configured to receive a signal from the generator, to emit radiation based on the received signal and to transmit the emitted radiation to the optical system of the transmitter configured to direct the emitted radiation within the scanning sector of the module, and each receiver comprises a group of photodetectors, an optical system of the receiver and a diaphragm, wherein the group of photodetectors is located in the focal plane of the optical system of the receiver, the diaphragm is located between the optical system of the receiver and the focal plane of the optical system of the receiver, and each photodetector of the group is configured to receive radiation reflected from the scanning object and having passed through the optical system of the receiver and the diaphragm, convert the radiation into a signal and transmit the signal to the signal processing channel corresponding to the photodetector, the microcontroller is configured to receive the signals processed in the processing channels for their joint processing in the microcontroller and to transmit the processing results to the processor, the processor is configured to position the scanning object based on the processing results received from each scanning module of the sensor.EFFECT: increased accuracy of positioning of the scanning object.10 cl, 3 dwg

Description

[0001] FIELD OF TECHNOLOGY

[0002] The invention relates to precision contactless positioning and control devices, specifically to a near-field sensor with modulated radiation. The present invention can be used for contactless data input in augmented reality devices that operate with virtual images, such as optical projection devices used in key sectors such as medicine, automotive, mechanical engineering, services, and others.

[0003] STATE OF THE ART

[0004] Various types of touch sensors for contactless data input are known from the prior art - IR emitters with a diffraction grating and a camera for image recognition, IR frames based on the intersection of beams (closed loop) (see, for example, patents US 8471830 B2, published on 25.06.2013, US 12147630 B2, published on 19.11.2024). However, IR emitters with a diffraction grating and a camera for image recognition require an opaque surface for operation and are therefore not suitable for working with mine images. IR frames based on the intersection of beams cannot be used to work with virtual images, since this would require the installation of response receivers opposite the emitters, which would block part of the virtual image.

[0005] The closest analogues are solutions containing IR emitters and receivers and based on the reflection of rays (open circuit), described in patents US 9921661 B2, published 03 / 20 / 2018, cl. G06F 3 / 01, G06F 1 / 16, G06F 17 / 00, G06F 3 / 042, G06F 3 / 0488, and US 10324565 B2, published 06 / 18 / 2019, cl. G06F 3 / 042; G01C 3 / 08; G01S 17 / 48; G01S 7 / 497; G06F 1 / 16; G06F 3 / 0488. A known near-field sensor for determining the location of an object comprises a housing; a plurality of light emitters mounted within said housing for projecting light from said housing along a detection plane; and a plurality of light detectors mounted within said housing, which, when activated, operate to detect the amount of light entering the housing along the detection plane, wherein the emitters and detectors are arranged alternately within the housing. However, such a configuration of the known sensor does not allow for accurate scanning with multiple touches (multi-touch).

[0006] The technical problem is to eliminate the above defect.

[0007] DISCLOSURE OF THE INVENTION

[0008] The technical problem solved by the present invention consists in developing a near-field sensor that is free from the disadvantages of the closest analogue.

[0009] The technical result achieved by the present invention is to increase the accuracy of the near-field touch sensor.

[0010] The above technical result is achieved by a near-field sensor with modulated radiation, containing at least one processor and n scanning modules, where n ≥ 1, connected to at least one processor,

[0011] wherein each scanning module is a multi-channel phase rangefinder containing a signal generator, a voltage source, a microcontroller, signal processing channels, a transmitter and a receiving group of one or two receivers, the transmitter and receiving group are located in the working plane of the sensor,

[0012] wherein the transmitter comprises an emitter configured to receive a signal from the generator, emit radiation based on the received signal and transmit the emitted radiation to an optical system of the transmitter configured to direct the emitted radiation within the scanning sector of the module,

[0013] and each receiver contains a group of photodetectors, an optical system of the receiver and a diaphragm, wherein the group of photodetectors is located in the focal plane of the optical system of the receiver, the diaphragm is located between the optical system of the receiver and the focal plane of the optical system of the receiver, and each photodetector of the group is configured to receive radiation reflected from the scanning object and passed through the optical system of the receiver and the diaphragm, convert the radiation into a signal and transmit the signal to the signal processing channel corresponding to the photodetector,

[0014] The microcontroller is configured to receive signals processed in the processing channels for their joint processing in the microcontroller and transmit the processing results to the processor,

[0015] the processor is configured to position the scanning object based on the processing results obtained from each scanning module of the sensor.

[0016] Increased scanning accuracy is achieved by using an array of multi-channel phase rangefinders for contactless positioning.

[0017] In one embodiment of the touch sensor, the emitter is an infrared laser and the photodetector is an infrared photodiode.

[0018] In another embodiment of the touch sensor, n scanning modules are a linear array of multi-channel phase range finders, wherein one or two receivers of the receiving group of each scanning module are located to the left and / or right of the transmitter of the module, wherein the transmitters and receivers of the n scanning modules of the touch sensor are located in one row in the working plane of the sensor.

[0019] In another embodiment of the sensor, the phase range finder is two-channel or three-channel, wherein the receiving group of the scanning module contains one receiver, and said receiver contains two or three photodetectors, respectively,

[0020] In another embodiment of the sensor, the phase range finder is six-channel, wherein the receiving group of the scanning module contains two receivers, and each receiver contains three photodetectors.

[0021] In another embodiment of the sensor, the diaphragm is configured to automatically move between the optical system of the receiver and the focal plane of the optical system of the receiver to determine the direction of the reflected radiation.

[0022] In another embodiment of the touch sensor, the optical system of the receiver of the receiving group of the scanning module is a lens, wherein one of the photodetectors is central and is located at the focus of the lens in the working plane of the sensor, while the other one or two photodetectors are lateral and are shifted to the left and / or right relative to the central photodetector in the working plane of the sensor.

[0023] In another embodiment, the touch sensor is configured to scan with or without an optical shadow, wherein the radiation angle of the scanning module transmitter for scanning without an optical shadow is greater than the radiation angle for scanning with an optical shadow, and the radiation angle of the transmitter depends on the required scanning range and the size of the touch sensor.

[0024] In another embodiment of the touch sensor, the processor is configured to sequentially or simultaneously activate the scanning modules.

[0025] In another embodiment of the sensor, the multi-channel phase range finder is a dual-frequency laser phase range finder with a heterodyne method.

[0026] BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the foregoing general description of the invention and the following detailed description of the embodiments, serve to explain the principles of the present invention.

[0028] The attached drawings are presented to explain the essence of the invention and in no way limit other, particular embodiments of its implementation that do not go beyond the scope of the requested scope of legal protection and are obvious to a specialist in this field of technology.

[0029] The present invention is illustrated by figures 1-3, which show:

[0030] Fig. 1 illustrates an exemplary embodiment of an optical circuit of a near-field infrared sensor comprising a linear array of six-channel laser phase range finders according to the present invention.

[0031] Fig. 2 illustrates a diagram for detecting multiple objects in a scanning area of ​​a near-field infrared sensor according to the present invention.

[0032] Fig. 3 illustrates an exemplary embodiment of the structural diagram of a three-channel dual-frequency laser phase range finder according to the present invention.

[0033] IMPLEMENTATION OF THE INVENTION

[0034] The detailed description of the embodiment of the invention provides numerous implementation details to ensure a clear understanding of the present invention. However, it is obvious to those skilled in the art how the present invention can be used with or without these implementation details. Furthermore, the present invention is not limited to the described implementation. Numerous possible modifications, changes, variations, and substitutions, while maintaining the spirit and form of the present invention, are obvious to those skilled in the art.

[0035] A near-field modulated-radiation sensor comprises at least one processor and n scanning modules, where n ≥ 1, connected to the at least one processor. Each scanning module is a multi-channel phase rangefinder, such as a multi-channel dual-frequency laser phase rangefinder with a heterodyne method.

[0036] Each phase rangefinder of the touch sensor contains a signal generator, a voltage source, a microcontroller, signal processing channels, a transmitter and a receiving group of one or two receivers, the transmitter and receiving group are located in the working plane of the sensor, n scanning modules are a linear array of multi-channel phase rangefinders, the transmitters and receivers of n scanning modules are located in one row in the working plane of the sensor, while one or two receivers of the receiving group of each scanning module are located to the left and / or right of the transmitter module.

[0037] The scanning module transmitter comprises an emitter configured to receive a signal from the generator, emit radiation based on the received signal, and transmit the emitted radiation to the transmitter's optical system, which is configured to direct the emitted radiation within the module's scanning sector. The emitter may be, for example, an infrared laser.

[0038] Each scanning module receiver contains a group of photodetectors, a receiver optical system, and a diaphragm. The photodetectors of the receiving group are connected by a common signal generator and a phase rangefinder power supply, thus sharing a common synchronous signal source. The photodetector is, for example, an infrared photodiode. The photodetector group is located in the focal plane of the receiver optical system, the diaphragm is located between the receiver optical system and the focal plane of the receiver optical system, and each photodetector in the group is configured to receive radiation reflected from the scanned object and transmitted through the receiver optical system and diaphragm, convert the radiation into a signal, and transmit the signal to the signal processing channel corresponding to the photodetector. The number of signal processing channels is equal to the number of photodetectors in the scanning module's receiving group.After processing the signals in the channels, they are then transmitted to the phase range finder microcontroller for mathematical (calculating the average) and logical (determining the direction of the incident (reflected) light beam) processing.

[0039] The optical system of the receiver of the scanning module's receiving group is, for example, a lens, wherein one of the photodetectors is central and located at the focal point of the lens in the sensor's working plane, while the other one or two photodetectors are lateral and offset to the left and / or right relative to the central photodetector in the sensor's working plane. The diaphragm can be configured to automatically move between the receiver's optical system and the focal plane of the receiver's optical system to determine the direction of reflected radiation.

[0040] The touch sensor processor is designed to activate scanning modules sequentially or simultaneously.

[0041] The microcontroller of each scanning module is configured to receive signals processed in the processing channels for their combined processing in the microcontroller and transmit the processing results to the processor. The processor is configured to position the scanned object based on the processing results received from each scanning module of the sensor.

[0042] The phase rangefinder can be two-channel or three-channel, wherein the receiving group of the scanning module contains one receiver, and said receiver contains two or three photodetectors, respectively.

[0043] The phase rangefinder can be six-channel, with the receiving group of the scanning module containing two receivers, and each receiver containing three photodetectors.

[0044] The near-field modulated-emission touch sensor according to the present invention can be configured to scan with or without optical shadow. Scanning with optical shadow does not allow the scanning objects to be positioned on top of each other during multi-touch. Scanning without optical shadow allows the scanning objects to be positioned on top of each other during multi-touch. The radiation angle of the scanning module's transmitter for scanning without optical shadow is larger than the radiation angle for scanning with optical shadow, and the radiation angle of the transmitter depends on the required scanning range and the size of the touch sensor.

[0045] Below is presented an embodiment of the present invention, which should not be used as limiting other, particular embodiments of the implementation of the present invention that do not go beyond the scope of the requested scope of legal protection and are obvious to a person skilled in the art.

[0046] Fig. 1 shows an optical diagram of a near-field infrared sensor comprising a linear array of six-channel laser phase range finders according to the present invention. The near-field sensor with modulated radiation is an array of laser phase range finders (LPR) and allows tracking objects using diffuse reflection of infrared light. IR rays are emitted perpendicular to the output plane of the sensor, and receivers are located to the left and to the right of the emitter in the plane of the module and receive reflected light from objects located in the tracking zone (Fig. 2). The sensor contains n scanning modules (Fig. 1). Each scanning module includes one transmitter and a group of receivers (a receiving group). The arrangement of receivers to the left and to the right of each emitter allows for an increase in the calculation accuracy due to additional close (reflection close to 90 degrees) measurements of the reflected signal.

[0047] Each transmitter contains one emitter (IR laser) and an optical system (lens) that ensures beam divergence within the distance between the scanning modules. The divergence angle is within 0.2 degrees for the solution with optical shadow (it is not possible to position scanned objects on top of each other during multi-touch), and 1.6 degrees for the solution without optical shadow (it is possible to position scanned objects on top of each other during multi-touch).

[0048] To achieve a solution without optical shadows, by expanding the beam (increasing the laser dispersion angle through the use of different lenses), it is possible to “illuminate” the blind zone above the scanning object (for example, a finger) with an adjacent signal (from an adjacent laser), receive a reflected signal from the object in the blind zone, which will be received by other receivers (including those outside its group), and process this signal.

[0049] Each scanning module receiver includes an optical system (lens) and three photodetectors (IR photodiodes). This arrangement allows the emitted / reflected IR beams and receiver fields of view to be combined within a single aperture with an offset of + / - the receiver sensor size. Each emitter / receiver combination covers a narrow sector of the active scanning area (+ / - 10 degrees from the emission line).

[0050] The central photodiodes are located in the center of the focal plane of the receiver's optical system, the side ones are shifted to the left and right relative to the central one in the horizontal plane of the system.

[0051] The approach of using a diaphragm above the focal plane allows for additional limitation of the scanning angle and determination of the radiation direction of coherent beams. By placing the diaphragm between the lens and the focal plane, it is possible to cut off some of the beams (i.e., reduce the field of view without changing the lenses or diode arrangement). By moving the diaphragm between the planes of the lens itself and its focal plane, it is possible to cut off some of the beams, thereby changing the visible scanning area of ​​a single module.

[0052] The presence of a diaphragm under the receiver lens allows for the determination of the direction of the reflected signal (left or right of the sensor), allowing for the determination of not only the distance to an object but also its position within the scanning sector of a single module. This solution, combined with a beam angle of over 1.5 degrees, eliminates the blind spot above the scanned object when scanning multiple objects.

[0053] An object present in the active area affects two or more channels of the scanning module, which allows the result of calculating the center of gravity from these signals to be used to determine the position of the tracking object.

[0054] Using different emitter frequencies in one scanning cycle allows you to increase the scanning accuracy and determine the size of the scanning object (to calculate the shift of its position from the lower boundary to the center of the object).

[0055] The calculation system is based on a phase shift measurement method with two modulation frequencies, one of which provides wide-range distance measurement, and the other with high resolution. The measurement method is based on an intermediate sampling frequency, combining subsampling with digital synchronous detection.

[0056] A classic laser phase rangefinder has the following technical limitations compared to a multi-channel laser phase rangefinder: the need for a generator with high stability over a wide temperature range and low phase delays; the necessity of using multiple laser modulation frequencies with a rigid phase relationship; the impossibility of using DDS (direct digital synthesis) circuits at high frequencies due to the lack of components and the high power consumption of such circuits; the dependence of the parameters of the electronic components of the laser phase rangefinder circuit on temperature; the impossibility of providing signal processing at high frequencies, which requires frequency conversion to the low-frequency region. Also, the use of only one receiver channel does not allow the use of mathematical methods for eliminating measurement errors.

[0057] Figure 3 shows an exemplary block diagram of a three-channel, dual-frequency laser phase rangefinder according to the present invention. An 80 MHz, temperature-compensated oscillator is used as the master oscillator, ensuring a frequency deviation of 0.1%. The oscillator's output is fed to a digital frequency divider, whose outputs generate a 2.5 MHz rectangular signal. The sampling (synchronization) frequency for the ADC is set to 2 MHz. These frequencies are phase-coupled, which is important for subsequent signal processing on multiple ADCs in parallel. The operating principle of the phase laser rangefinder is that the reflected wave arrives in different phases depending on the distance to the target.In other words, if the laser is currently emitting a signal in a certain phase, the reflected signal may return at the same time it was emitting a signal in a different phase, since the phase of the emitted signal changes within the device itself during the time it takes the light to travel to the measured object and back. Since it's unknown how many wavelengths are included in a single measurement, the rangefinder changes the modulation frequency and repeats the measurement. The processor in the rangefinder then solves a system of linear equations and calculates the distance to the target. The accuracy of the result is determined by the phase shift measurement accuracy and can reach 0.5 mm.This circuit implements the following technical solutions: heterodyne frequency conversion of the signal to the low-frequency region (LF-region) while preserving phase information; frequency conversion of the signal to the LF-region using pre-filters during sampling; a method of digital signal filtering instead of analog filters; a highly efficient digital phase meter is used; an algorithm for statistical processing and averaging of the result is used.

[0058] The present invention enables the use of different emitter frequencies in a single scan cycle (increasing scanning accuracy and determining the size of the scanned object to calculate its positional shift from the lower boundary to the center of the object). It also utilizes a single phase shift measurement stage, and dual modulation frequency is possible thanks to the heterodyne method. The emitter and detector sections of the sensor are suitable for wideband operation and are digitally controlled. Furthermore, the system is designed with only one digital phase-locked loop, reducing phase noise and improving measurement accuracy.

[0059] These application materials present a preferred disclosure of the implementation of the present invention, which should not be used as limiting other, particular embodiments of its implementation that do not go beyond the scope of the requested scope of legal protection and are obvious to a person skilled in the art.

[0060] It should be clear to a person skilled in the art that various variations of the disclosed technical solution do not change the essence of the invention, but only determine its specific embodiments and applications.

Claims

1. A near-field modulated radiation sensor comprising at least one processor and n scanning modules, where n ≥ 1, connected to the at least one processor, wherein each scanning module is a multi-channel phase range finder containing a signal generator, a voltage source, a microcontroller, signal processing channels, a transmitter and a receiving group of one or two receivers, the transmitter and receiving group are located in the working plane of the sensor, wherein the transmitter comprises an emitter configured to receive a signal from the generator, emit radiation based on the received signal and transmit the emitted radiation to the optical system of the transmitter configured to direct the emitted radiation within the scanning sector of the module, and each receiver contains a group of photodetectors, an optical system of the receiver and a diaphragm, wherein the group of photodetectors is located in the focal plane of the optical system of the receiver, the diaphragm is located between the optical system of the receiver and the focal plane of the optical system of the receiver, and each photodetector of the group is configured to receive radiation reflected from the scanning object and passed through the optical system of the receiver and the diaphragm, convert the radiation into a signal and transmit the signal to the signal processing channel corresponding to the photodetector, the microcontroller is configured to receive signals processed in the processing channels for their joint processing in the microcontroller and transmit the processing results to the processor, the processor is configured to position the scanning object based on the processing results obtained from each scanning module of the sensor.

2. A touch sensor according to paragraph 1, characterized in that the emitter is an infrared laser, and the photodetector is an infrared photodiode.

3. The sensor according to claim 1, characterized in that n scanning modules are a linear array of multi-channel phase range finders, wherein one or two receivers of the receiving group of each scanning module are located to the left and / or right of the transmitter of the module, wherein the transmitters and receivers of n scanning modules of the sensor are located in one row in the working plane of the sensor.

4. The sensor according to claim 1, characterized in that the phase range finder is two-channel or three-channel, wherein the receiving group of the scanning module contains one receiver and said receiver contains two or three photodetectors, respectively.

5. The sensor according to claim 1, characterized in that the phase range finder is six-channel, wherein the receiving group of the scanning module contains two receivers and each receiver contains three photodetectors.

6. A sensor according to claim 1, characterized in that the diaphragm is designed with the possibility of automatic movement between the optical system of the receiver and the focal plane of the optical system of the receiver to determine the direction of reflected radiation.

7. The touch sensor according to claim 1, characterized in that the optical system of the receiver of the receiving group of the scanning module is a lens, wherein one of the photodetectors is central and is located at the focus of the lens in the working plane of the sensor, while the other one or two photodetectors are lateral and are shifted to the left and / or right relative to the central photodetector in the working plane of the sensor.

8. The touch sensor according to claim 1, characterized in that it is designed with the possibility of scanning with or without an optical shadow, wherein the radiation angle of the scanning module transmitter for scanning without an optical shadow is greater than the radiation angle for scanning with an optical shadow, and the radiation angle of the transmitter depends on the required scanning range and on the size of the touch sensor.

9. The touch sensor according to claim 1, characterized in that the processor is designed with the possibility of sequential or simultaneous activation of scanning modules.

10. The sensor according to claim 1, characterized in that the multi-channel phase rangefinder is a dual-frequency laser phase rangefinder with a heterodyne method.

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