A non-contact human-computer interaction system based on human infrared radiation detection

Abstract

The application provides a non-contact human-computer interaction system based on human infrared radiation detection. The application comprises a thermoelectric pile, an amplification circuit and a voltage comparison circuit connected in sequence, the thermoelectric pile is used for detecting human infrared radiation and converting optical signals into voltage signals, wherein the thermoelectric pile comprises a substrate, a plurality of perovskite type composite oxides and metal wires, the substrate has a preset thermal conductivity, one end of the perovskite type composite oxides is connected to the substrate, the other end is provided in a suspended manner, and the adjacent perovskite type composite oxides are connected through the metal wires. The application can further comprise a multi-channel data acquisition module, a microprocessor and a display module, the non-contact human-computer interaction system provides two operation modes of proximity switches and gesture recognition. The application realizes sensitive detection of human infrared radiation by using the thermoelectric pile based on the perovskite type composite oxides, and further constructs the non-contact human-computer interaction system, and the system has the advantages of simple structure, low required power consumption and multiple recognizable gestures.

Description

Technical Field

[0001] This invention relates to the field of non-contact human-computer interaction, and more particularly to a non-contact human-computer interaction system based on human infrared radiation detection. Specifically, it refers to using a thermopile based on perovskite composite oxide to achieve sensitive detection of human radiation, and further using gestures to selectively trigger the thermopile array to achieve non-contact human-computer interaction functions. Background Technology

[0002] The use of contactless human-computer interaction technology in public places can avoid cross-infection and cut off the transmission path of viruses. The core of contactless human-computer interaction technology is the sensor, which can be divided into two main categories: active and passive. Active sensors, such as near-infrared proximity switches, consist of a continuous transmitter and a receiver, thus requiring high power consumption. Passive sensors detect signals related to the human body, commonly including self-heating radiation from the human body, humidity distribution caused by perspiration, and the charge accumulated on the human surface. Compared to passive sensors based on humidity distribution and human surface charge, sensors based on human thermal radiation have advantages such as reliable excitation sources and adjustable sensing range. However, the photons emitted by the human body have relatively weak energy, mainly concentrated in the long-wave infrared band (8-14μm), and the radiation power is low, around 5mW / cm². 2 Therefore, the realization of a non-contact human-computer interaction system based on human body radiation detection is inseparable from the development of highly sensitive long-wave infrared detectors.

[0003] Photothermal detectors are a type of thermistor, comprising photothermal conversion and thermoelectric conversion. The principle is to convert absorbed radiation into heat energy, creating a temperature gradient across the thermoelectric material. The Seebeck effect drives the directional movement of charge carriers in the thermoelectric material, generating a potential difference. Photothermal detectors offer advantages such as a wide spectral response range, no need for cooling, and no reliance on external power, making them particularly suitable for low-power long-wave infrared detection applications. Currently, commercially available photothermal detectors employ a thermopile structure to achieve high voltage response, consisting of multiple pairs of pn thermoelectric junctions distributed around the infrared absorber. For example, the SMTIR9901 thermopile produced by Smartec in the Netherlands consists of 100 pairs of BiSb / NiCr thermoelectric junctions. Therefore, the fabrication process of commercial photothermal detectors is relatively complex. On the other hand, while commercial photothermoelectric detectors possess high sensitivity (e.g., the SMTIR9901 thermopile has a sensitivity of up to 110 V / W), their output voltage is limited to only a few hundred microvolts when detecting human radiation due to their small photosensitive area (the SMTIR9901 thermopile has a photosensitive area of ​​0.5 mm²). In practical applications, such a low voltage output places high demands on the performance of subsequent amplification circuits. The applicant disclosed an ultra-wideband photothermoelectric detector based on perovskite composite oxides in Chinese patent application number 201810444716.9. Perovskite composite oxides possess unique strong correlation properties, often exhibiting a large effective carrier mass, resulting in a considerably high Seebeck coefficient. Furthermore, the presence of titanium-oxygen bonds in perovskite composite oxides leads to strong phonon absorption in the long-wave infrared band. These two characteristics enable perovskite composite oxides to possess both high long-wave infrared absorption and thermoelectric conversion capabilities. Therefore, thermopile based on perovskite composite oxides is expected to simplify the structure of traditional thermopile while enabling sensitive detection of human body radiation, and thus be used in the construction of non-contact human-computer interaction systems. Summary of the Invention

[0004] To address the aforementioned technical problems, a non-contact human-computer interaction system based on human infrared radiation detection is provided. This system utilizes a thermopile based on perovskite composite oxides to convert human infrared radiation into electrical signals, and further achieves non-contact human-computer interaction by selectively triggering the thermopile array through gestures. The technical means employed in this invention are as follows:

[0005] A non-contact human-computer interaction system based on human infrared radiation detection includes a thermopile, an amplifier circuit, and a voltage comparison circuit connected in sequence. The thermopile is used to detect human infrared radiation and convert the light signal into a voltage signal. The thermopile includes a substrate, several perovskite composite oxides, and metal wires. The substrate has a preset thermal conductivity. One end of each perovskite composite oxide is connected to the substrate, and the other end is suspended. Adjacent perovskite composite oxides are connected by metal wires.

[0006] Furthermore, the substrate is provided with circular through holes, and the perovskite composite oxide is cuboid in shape. Each perovskite composite oxide is symmetrically distributed around the center of the through hole and along its radial direction, with the suspended side of the cuboid perovskite composite oxide located at the center.

[0007] Furthermore, a thermally conductive insulating medium is filled between the perovskite-type composite oxide and the substrate.

[0008] Furthermore, adjacent perovskite-type composite oxides are connected end to end by metal wires to form a radial thermopile structure.

[0009] Furthermore, the working mode of the aforementioned non-contact human-machine interaction system based on human infrared radiation detection is a proximity switch. The output of the thermopile is connected to the amplification circuit, and the amplified signal is transmitted to the voltage comparison circuit. When a human body approaches the thermopile, the thermopile converts the human body's infrared radiation into a voltage signal. When the amplified voltage signal exceeds the reference voltage of the comparison circuit, the comparison circuit outputs a high level to provide power to the back-end indicator circuit or actuator.

[0010] This invention also discloses a non-contact human-computer interaction system based on human infrared radiation detection with gesture recognition as its working mode. The system includes a thermopile, a multi-channel data acquisition module, a microprocessor, and a display module connected in sequence. The thermopile consists of at least two thermopile units used to detect human infrared radiation and convert light signals into voltage signals. Each thermopile includes a substrate, several perovskite composite oxides, and metal wires. The substrate has a preset thermal conductivity. One end of each perovskite composite oxide is connected to the substrate, and the other end is suspended. Adjacent perovskite composite oxides are connected by metal wires.

[0011] The multi-channel data acquisition module is used to acquire multi-channel voltage signals of the thermopile array and transmit the voltage signals to the microprocessor;

[0012] The microprocessor is used to process the voltage signal acquired by the multi-channel data acquisition module, identify the trigger sequence of the thermopile array, and realize non-contact human-computer interaction function according to the correspondence between the trigger sequence and the gesture.

[0013] Furthermore, the substrate is provided with circular through holes, and the perovskite composite oxide is cuboid in shape. Each perovskite composite oxide is symmetrically distributed around the center of the through hole and along its radial direction, with the suspended side of the cuboid perovskite composite oxide located at the center.

[0014] Furthermore, a thermally conductive insulating medium is filled between the perovskite-type composite oxide and the substrate.

[0015] Furthermore, adjacent perovskite-type composite oxides are connected end to end by metal wires to form a radial thermopile structure.

[0016] Furthermore, the working mode is gesture recognition. Several thermopile arrays are arranged in a two-dimensional array. The output signal of each thermopile is recorded by a multi-channel data acquisition module. When a finger moves above the thermopile array, the corresponding thermopile is triggered and generates an electrical signal. The multi-channel data acquisition module is connected to a microprocessor. The microprocessor extracts the trigger sequence of the thermopile array, and the display module outputs the gesture information corresponding to the trigger sequence, thereby realizing non-contact human-computer interaction function.

[0017] The two non-contact human-computer interaction systems based on human infrared radiation detection, which have different working modes, disclosed in this invention can be used together in parallel or separately.

[0018] The present invention has the following advantages:

[0019] 1. This invention utilizes a thermopile based on perovskite-type composite oxides to detect human infrared radiation, offering advantages such as no need for cooling, no need for bias voltage, simple structure, high sensitivity, and low noise. Compared to the relatively low maximum response voltage of existing commercial thermopiles, this invention exhibits a significantly higher response voltage under the same testing conditions, enabling effective and sensitive detection of human radiation.

[0020] 2. This invention utilizes a thermopile based on perovskite-type composite oxides to achieve contactless human-computer interaction. This contactless human-computer interaction system can be used as a short-range proximity switch and gesture recognition, and has advantages such as low power consumption and weak signal crosstalk between pixels. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a thermopile structure based on perovskite-type composite oxides in an embodiment of the present invention;

[0023] Figure 2 This refers to the response voltage generated by strontium titanate-based thermopile and commercial thermopile when detecting infrared radiation from a human hand.

[0024] Figure 3 Voltage noise spectra of strontium titanate-based thermopile and commercial thermopile.

[0025] Figure 4 This is a schematic diagram of a proximity switch circuit for a thermopile based on perovskite composite oxides in an embodiment of the present invention.

[0026] Figure 5 This refers to the voltage response at each node in the proximity switch circuit when a finger approaches or moves away from the thermopile.

[0027] Figure 6 This refers to the non-contact human-computer interaction system based on a 2×2 thermopile array prepared in the embodiments of the present invention.

[0028] Figure 7 The voltage output of each thermopile is given when a finger is moved clockwise over a 2×2 thermopile array.

[0029] In the figure: 1. Perovskite-type composite oxide; 2. High thermal conductivity substrate; 3. Circular through-hole; 4. Metal wire; 5. Metal coating. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment provides a thermopile based on strontium titanate. First, a strip-shaped insulating strontium titanate crystal with dimensions of 6mm × 0.25mm × 0.10mm (length × width × thickness) is subjected to hydrogen reduction treatment to form oxygen vacancies, thereby obtaining conductivity. In this embodiment, the perovskite-type composite oxide 1 is a regular cuboid shape; in other optional embodiments, it can also be other suitable production shapes. The reduced strontium titanate has a resistivity of 3.2 kΩ and a Seebeck coefficient of -740 μV / K, where the negative sign indicates that electrons are the majority carriers. A high thermal conductivity aluminum-based printed circuit board is used as the substrate 2, with a 5mm diameter circular through-hole 3 in the center. One end of the cuboid-shaped perovskite-type composite oxide on the substrate is electrically connected to a metal plating layer 5, and the suspended side is connected to a metal wire 4. The entire series sequence is: metal plating layer - cuboid-shaped perovskite-type composite oxide - metal wire - metal plating layer. Four elongated strontium titanate crystals are symmetrically distributed radially around the center of a through-hole. One side of the strontium titanate crystals near the center is suspended, while the other side rests on an aluminum-based printed circuit board, with thermally conductive silicone grease filling the space between them. A schematic diagram of the thermopile based on perovskite composite oxide is shown below. Figure 1 As shown, due to the heat sink effect of the aluminum-based printed circuit board, when a finger is placed on the thermopile, only the temperature of the strontium titanate on the suspended side rises, becoming the hot end, while the temperature on the other side remains almost unchanged, becoming the cold end. This creates a temperature gradient along the length of the strontium titanate crystal, forming a potential difference. By connecting the hot and cold ends of four strontium titanate crystals end to end with platinum wire, forming an electrical series connection, a thermopile is constructed to increase the response voltage.

[0033] As a finger gradually approaches the strontium titanate-based thermopile from directly above, the response voltage of the thermopile changes as follows: Figure 2 As shown, its response voltage increases exponentially, reaching a maximum of approximately 10mV. Under the same test conditions, the maximum response voltage of the SMTIR9901 commercial thermopile from the Dutch company Smartec is only around 0.5mV. Figure 3 Regarding noise performance, the background noise of the strontium titanate-based thermopile is 11 nV / Hz. 1 / 2 It is significantly superior to the commercial SMTIR9901 thermopile (28nV / Hz). 1 / 2 This is because the resistance of the strontium titanate-based thermopile (4.8kΩ) is much smaller than that of the commercial SMTIR9901 thermopile (46kΩ), and the noise of the thermopile is directly related to its resistance.

[0034] Building upon the highly sensitive detection of human infrared radiation achieved using a strontium titanate-based thermopile, this embodiment utilizes the strontium titanate-based thermopile for a proximity switch to sense the approach of a finger. This proximity switch includes a thermopile, an amplifier circuit, a comparator circuit, and an LED indicator. Figure 4The output wires of the thermopile are connected to the amplifier circuit, and the amplified signal is transmitted to the comparator circuit. Figure 5 The voltage changes at various points were recorded as a person's hand approached and moved away from the thermopile when the amplification factor was 120x and the reference voltage of the comparator circuit was 47mV. Once the amplified thermopile voltage signal exceeded the reference voltage of the comparator circuit, the comparator circuit immediately output a high level (3.1V) to light up the LED indicator.

[0035] Example 2

[0036] This embodiment provides a strontium titanate-based thermopile array and its application in non-contact gesture recognition. Based on the strontium titanate-based thermopile of Embodiment 1, four strontium titanate-based thermopiles are arranged in a 2×2 array, and the output signal of each thermopile is recorded using a multi-channel data acquisition module. Figure 6 When a finger moves over the thermopile array, the corresponding thermopile is selectively triggered, generating an electrical signal. Figure 7 The output voltage of each thermopile was recorded when a finger moved clockwise above the thermopile array. It can be seen that as the finger moves, each thermopile is triggered sequentially, and the response time constant of the rise / fall process of the thermopile voltage signal is within 1 second. Further, by extracting the rising edge sequence of the multi-channel voltage signal using a microprocessor and establishing a mapping relationship between the rising edge sequence and the gesture, a contactless human-computer interaction function can be realized.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-contact human-computer interaction system based on human infrared radiation detection, characterized in that, The device includes a thermopile, an amplifier circuit, and a voltage comparator circuit connected in sequence. The thermopile is used to detect infrared radiation from the human body and convert the light signal into a voltage signal. The thermopile includes a substrate, several perovskite composite oxides, and metal wires. The substrate has a preset thermal conductivity. One end of each perovskite composite oxide is connected to the substrate, and the other end is suspended. Adjacent perovskite composite oxides are connected by metal wires.

2. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 1, characterized in that, The substrate has a circular through hole, and the perovskite composite oxide is cuboid in shape. Each perovskite composite oxide is symmetrically distributed around the center of the through hole and along its radial direction. The suspended side of the cuboid perovskite composite oxide is located at the center of the circle.

3. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 1, characterized in that, A thermally conductive and insulating medium is filled between the perovskite-type composite oxide and the substrate.

4. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 1, characterized in that, Adjacent perovskite composite oxides are connected end-to-end by metal wires to form a radial thermopile structure.

5. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 1, characterized in that, The operating mode is a proximity switch. The output of the thermopile is connected to the amplifier circuit. The amplified signal is transmitted to the voltage comparator circuit. When a human body approaches the thermopile, the thermopile converts the human body's infrared radiation into a voltage signal. When the amplified voltage signal exceeds the reference voltage of the comparator circuit, the comparator circuit outputs a high level, providing power to the downstream indicator circuit or actuator.

6. A non-contact human-computer interaction system based on human infrared radiation detection, characterized in that, The device includes a thermopile, a multi-channel data acquisition module, a microprocessor, and a display module connected in sequence. There are at least two thermopiles, which are used to detect infrared radiation from the human body and convert light signals into voltage signals. The thermopile includes a substrate, several perovskite composite oxides, and metal wires. The substrate has a preset thermal conductivity. One end of each perovskite composite oxide is connected to the substrate, and the other end is suspended. Adjacent perovskite composite oxides are connected by metal wires. The multi-channel data acquisition module is used to acquire multi-channel voltage signals of the thermopile array and transmit the voltage signals to the microprocessor; The microprocessor is used to process the voltage signal acquired by the multi-channel data acquisition module, identify the trigger sequence of the thermopile array, and realize non-contact human-computer interaction function according to the correspondence between the trigger sequence and the gesture.

7. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 6, characterized in that, The substrate has a circular through hole, and the perovskite composite oxide is cuboid in shape. Each perovskite composite oxide is symmetrically distributed around the center of the through hole and along its radial direction. The suspended side of the cuboid perovskite composite oxide is located at the center of the circle.

8. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 6, characterized in that, A thermally conductive and insulating medium is filled between the perovskite-type composite oxide and the substrate.

9. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 6, characterized in that, Adjacent perovskite composite oxides are connected end-to-end by metal wires to form a radial thermopile structure.

10. The non-contact human-computer interaction system based on human infrared radiation detection as described in claim 6, characterized in that, The working mode is gesture recognition. Several thermopile arrays are arranged in a two-dimensional array. The output signal of each thermopile is recorded by a multi-channel data acquisition module. When a finger moves above the thermopile array, the corresponding thermopile is triggered and generates an electrical signal. The multi-channel data acquisition module is connected to a microprocessor. The microprocessor extracts the trigger sequence of the thermopile array, and the display module outputs the gesture information corresponding to the trigger sequence, thereby realizing non-contact human-computer interaction.

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