Object detection sensor

Abstract

The utility model discloses an object detection sensor and a detection method. Wherein the detection sensor comprises a light emitting part, a light guide channel, a light receiving part and a control part, and the light emitting part is used for emitting a light beam to a to-be-detected object platform; the light receiving part is used for receiving partially reflected light beams of the to-be-measured object platform; the light guide channel is used for guiding part of reflected light beams of the to-be-measured object platform to the light receiving part; the control part is connected with the light emitting part and the light receiving part and used for controlling photoelectric signal conversion of the light emitting part and the light receiving part. According to the utility model, the requirement on a to-be-detected object is greatly reduced, the detection application range is greatly increased, and the detection sensitivity and accuracy are high.

Description

Technical Field

[0001] The utility model relates to the technical field of sensors, and specifically to an object detection sensor and a detection method. Background Art

[0002] An object detection sensor is used to detect whether an object passes through a measured channel or point, and is widely used in the scenario of object counting.

[0003] In the prior art, an optical fiber sensor is often used as an object detection sensor. It outputs light through an optical fiber and reflects it on the surface of an object and then transmits it back to another optical fiber for the sensor to identify. However, its sensitivity is low, and it has high requirements for the color, material, thickness, etc. of the object, and it is difficult to adjust and has poor stability. Summary of the Utility Model

[0004] Other features and advantages of the present utility model will be described in the following specification, and will be partially obvious from the specification, or will be understood by implementing the present utility model. The objectives and other advantages of the present utility model can be realized and obtained through the structures specifically pointed out in the specification and other specification drawings.

[0005] The objective of the present utility model is to overcome the above deficiencies, and the present utility model provides an object detection sensor and a detection method.

[0006] The technical solution adopted by the present utility model to solve its technical problems is: an object detection sensor, including a light emitting part, a light guiding channel, a light receiving part and a control part,

[0007] The light emitting part is used to emit a light beam to the platform of the object to be measured;

[0008] The light receiving part is used to receive a part of the reflected light beam from the platform of the object to be measured;

[0009] The light guiding channel is used to guide a part of the reflected light beam from the platform of the object to be measured to the light receiving part;

[0010] The control part is respectively connected to the light emitting part and the light receiving part and is used to control the photoelectric signal conversion of the light emitting part and the light receiving part.

[0011] By setting the light guiding channel and the control part, after the light beam is emitted to the platform of the object to be measured, the light beam reflected by the surface of the platform of the object to be measured returns to the light receiving part through the light guiding channel, and the control part judges the intensity of the reflected light beam received by the light receiving part, and then outputs a signal indicating whether an object is detected. The requirements for the object to be measured are greatly reduced, the detection applicable range is greatly increased, and the detection sensitivity and accuracy are high.

[0012] In some embodiments, the central axis of the light guide channel is axisymmetric and intersects with the beam emission central axis of the light emitting part. By setting the central axis of the light guide channel to be axisymmetric with the beam emission central axis of the light emitting part, the present invention ensures that the angle between the central axis of the light guide channel and the platform of the object to be measured is the same as the angle between the beam emission central axis of the light emitting part and the platform of the object to be measured, thereby making the beam signal received by the light receiving part more accurate.

[0013] In some embodiments, the length of the light guide channel is at least 5 mm. The length of the light guide channel is related to the thickness of the emitted beam. Thinner beams can use shorter light guide channels, but it should be at least not less than 5 mm. By setting the length of the light guide channel, the present invention ensures that the reflected beam can be comprehensively filtered in the light guide channel, greatly improving the detection accuracy. In addition, the longer the length of the light guide channel, the thinner the object to be measured that can be detected, and the higher the sensitivity.

[0014] In some embodiments, the light guide channel is a non-transparent channel. By setting the light guide channel to be non-transparent, the present invention can ensure that the reflected beam smoothly returns to the light receiving part.

[0015] In some embodiments, the control part includes a light driving circuit, a light receiving circuit and a power supply. The light driving circuit is used to drive the light emitting part to emit a light signal, the light receiving circuit is used to control the light receiving part to receive the light signal, and the power supply provides electrical energy for the light driving circuit and the light receiving circuit. By setting a control part with a light driving circuit, a light receiving circuit and a power supply, the present invention can convert the light signal into an electrical signal to form a signal indicating whether an object is detected, with high sensitivity.

[0016] In some embodiments, the light driving circuit includes a first-stage voltage regulator, a second-stage voltage regulator, a diode, and a light signal outputter. The input end of the first-stage voltage regulator is connected to the output end of the power supply through the diode, the output end of the first-stage voltage regulator is connected to the input end of the second-stage voltage regulator, and the output end of the second-stage voltage regulator is connected to the light signal outputter. By setting a diode to protect the input power supply polarity, and through the dual voltage regulation effects of the first-stage voltage regulator and the second-stage voltage regulator on the input voltage, the present invention ensures the output of the light signal.

[0017] In some embodiments, a resistor is connected between the input end of the second-stage voltage regulator and the output end of the first-stage voltage regulator.

[0018] The present invention sets a resistor between the second-stage voltage regulator and the first-stage voltage regulator to play a role in current limiting.

[0019] In some embodiments, the optical receiving circuit includes an optical signal inputter, a signal amplifier, a voltage comparator, and a signal outputter. The positive input terminal of the signal amplifier is connected to the optical signal inputter. The negative input terminal of the voltage comparator is connected to the output terminal of the signal amplifier. The positive input terminal of the voltage comparator is connected to the output terminal of the first-stage voltage regulator. The output terminal of the voltage comparator is connected to the signal outputter. By providing an optical receiving circuit having an optical signal inputter, a signal amplifier, a voltage comparator, and a signal outputter, after the optical signal is input, it is amplified by the signal amplifier and then compared by the voltage comparator to form an output signal indicating whether an object is detected.

[0020] In some embodiments, a resistor is connected between the output terminal of the signal amplifier and the negative input terminal of the voltage comparator, and a resistor is connected between the output terminal of the voltage comparator and the signal outputter. By providing a resistor between the signal amplifier and the voltage comparator, it plays a role in signal filtering; by providing a resistor between the voltage comparator and the signal outputter, it plays a role in current limiting.

[0021] The present invention also provides a detection method for an object detection sensor. The method is executed by the object detection sensor, and the object detection sensor includes a light emitting part, a light receiving part, a light guiding channel, and a control part having a light driving circuit, an optical receiving circuit, and a power supply. The method includes

[0022] Emitting a light beam, driving the light emitting part to emit a light beam to the platform of the object to be measured through the light driving circuit;

[0023] Receiving the light beam, the surface of the platform of the object to be measured reflects the light beam and passes through the light guiding channel to the light receiving part to receive the light beam;

[0024] Outputting a level signal, converting the light beam signal into an electrical signal through the optical receiving circuit and outputting a level signal.

[0025] By emitting a light beam to the platform of the object to be measured, the platform of the object to be measured will reflect the light beam back to the light receiving part, and then the control part judges the intensity of the reflected light beam received by the light receiving part, and further judges whether the object to be measured is detected.

[0026] When the light beam is emitted from the light emitting part to the platform of the object to be measured and there is no object to be measured on the platform of the object to be measured, the light beam will be reflected by the platform of the object to be measured and return to the light receiving part through the light guiding channel. At this time, the control part will output a low level;

[0027] When a light beam is emitted from a light emitting unit to a platform of an object to be measured, and there is an object to be measured on the platform of the object to be measured, the light beam encounters the object to be measured and is reflected by the object to be measured. At this time, the trajectory of the reflected light beam is changed, so that the strong light of the reflected light beam cannot enter the light guiding channel, while the weak light can enter the light guiding channel and return to the light receiving unit. At this time, the control unit will output a high level.

[0028] By adopting the above technical solution, the beneficial effects of the present utility model are:

[0029] In the present utility model, a light beam is emitted to the platform of the object to be measured, and the platform of the object to be measured will reflect the light beam back to the light receiving unit. Then, the control unit judges the intensity of the reflected light beam received by the light receiving unit, and further judges whether the object to be measured is detected. When the light beam is emitted from the light emitting unit to the platform of the object to be measured, and there is no object to be measured on the platform of the object to be measured, the light beam will be reflected by the platform of the object to be measured and return to the light receiving unit through the light guiding channel. At this time, the control unit will output a low level; when the light beam is emitted from the light emitting unit to the platform of the object to be measured, and there is an object to be measured on the platform of the object to be measured, the light beam encounters the object to be measured and is reflected by the object to be measured. At this time, the trajectory of the reflected light beam is changed, so that the strong light of the reflected light beam cannot enter the light guiding channel, while the weak light can enter the light guiding channel and return to the light receiving unit. At this time, the control unit will output a high level.

[0030] The present utility model has no special requirements for the object to be measured, such as the color, material, thickness, etc. of the object to be measured. Its detection scope is large, the sensitivity is high, and the accuracy is high.

[0031] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure.

[0032] Undoubtedly, such purposes of the present utility model and other purposes will become more obvious after the details of the preferred embodiments described in the following with multiple drawings and illustrations are described.

[0033] To make the above and other purposes, features and advantages of the present utility model more obvious and understandable, one or several preferred embodiments are specifically given below, and in conjunction with the attached drawings, the detailed description is as follows. Description of the Drawings

[0034] The drawings are used to provide a further understanding of the present utility model, and constitute a part of the specification. They are used together with the embodiments of the present utility model to explain the present utility model, and do not constitute a limitation to the present utility model.

[0035] In the drawings, the same components are denoted by the same reference numerals, and the drawings are schematic and not necessarily drawn to actual scale.

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only one or several embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on such drawings.

[0037] Figure 1 Schematic diagram of the object detection sensor structure of some embodiments of the present invention;

[0038] Figure 2 Schematic diagram of the light beam path when no object is detected in some embodiments of the present invention;

[0039] Figure 3 Schematic diagram of the light beam path when an object is detected in some embodiments of the present invention;

[0040] Figure 4 Schematic diagram of the structural principle of the control unit in some embodiments of the present invention.

[0041] Main reference numeral description:

[0042] 1. Light emitting part; 2. Light receiving part; 3. Light guiding channel; 4. Control part; 5. Platform of object to be measured; 6. Object to be measured. Specific implementation manners

[0043] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further details the present invention in combination with specific implementation manners. It should be understood that the specific implementation manners described here are only used to explain the present invention, but not to limit the present invention.

[0044] In addition, in the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0045] In the present utility model, unless otherwise clearly defined, terms such as "installation", "connection", "linkage", "fixation", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a direct connection, or an indirect connection through an intermediate medium, and may be the internal communication between two components or the interaction relationship between two components. However, indicating a direct connection means that there is no connection relationship constructed through a transition structure between the two connected main bodies, and they are only connected through the connection structure to form a whole. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0046] In the present utility model, unless otherwise clearly defined, the first feature being "above" or "below" the second feature may be a direct contact between the first and second features, or an indirect contact between the first and second features through an intermediate medium. In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0047] Refer to Figure 1 , Figure 1 is a schematic structural diagram of an object detection sensor according to some embodiments of the present utility model.

[0048] According to some embodiments of the present utility model, the present utility model provides an object detection sensor. The object detection sensor includes a light emitting part 1, a light guiding channel 3, a light receiving part 2, and a control part 4. The light emitting part 1 is used to emit a light beam to a platform of an object to be measured 5; the light receiving part 2 is used to receive a part of the reflected light beam from the platform of the object to be measured 5; the light guiding channel 3 is used to guide a part of the reflected light beam from the platform of the object to be measured 5 to the light receiving part 2; the control part 4 is respectively connected to the light emitting part 1 and the light receiving part 2 and is used to control the photoelectric signal conversion of the light emitting part 1 and the light receiving part 2.

[0049] By providing the light guiding channel 3 and the control part 4, after the light beam is emitted to the platform of the object to be measured 5 in the present utility model, the light beam reflected by the surface of the platform of the object to be measured 5 returns to the light receiving part 2 through the light guiding channel 3, and the control part 4 determines the intensity of the reflected light beam received by the light receiving part 2, and then outputs a signal indicating whether an object is detected. The requirements for the object to be measured 6 are greatly reduced, the detection applicable range is greatly increased, and the detection sensitivity and accuracy are high.

[0050] According to some embodiments of the present invention, preferably, the central axis of the light guide channel 3 is axisymmetric and intersects with the beam emission central axis of the light emitting part 1. By setting the central axis of the light guide channel 3 to be axisymmetric with the beam emission central axis of the light emitting part 1, the present invention ensures that the angle between the central axis of the light guide channel 3 and the object to be measured platform 5 is the same as the angle between the beam emission central axis of the light emitting part 1 and the object to be measured platform 5, thereby making the beam signal received by the light receiving part 2 more accurate.

[0051] According to some embodiments of the present invention, preferably, the length of the light guide channel is at least 5 mm. The length of the light guide channel 3 is related to the thickness of the emitted light beam. Thinner light beams can use shorter light guide channels 3, but it should be at least not less than 5 mm. By setting the length of the light guide channel 3, the present invention ensures that the reflected light beam can be comprehensively filtered in the light guide channel 3, greatly improving the detection accuracy. In addition, the longer the length of the light guide channel 3, the thinner the object to be measured 6 that can be detected, and the higher the sensitivity.

[0052] According to some embodiments of the present invention, preferably, the light guide channel 3 is a non-transparent channel. By setting the light guide channel 3 to be non-transparent, the present invention can ensure that the reflected light beam smoothly returns to the light receiving part 2.

[0053] Refer to Figure 4 , Figure 4 which is a schematic structural principle diagram of the control part 4 in some embodiments of the present invention.

[0054] According to some embodiments of the present invention, preferably, the control part 4 includes a light driving circuit, a light receiving circuit, and a power supply. The light driving circuit is used to drive the light emitting part 1 to emit a light signal, the light receiving circuit is used to control the light receiving part 2 to receive the light signal, and the power supply provides electrical energy for the light driving circuit and the light receiving circuit. By setting the control part 4 with a light driving circuit, a light receiving circuit, and a power supply, the present invention can convert the light signal into an electrical signal to form a signal indicating whether an object is detected, with high sensitivity.

[0055] According to some embodiments of the present utility model, preferably, the light driving circuit includes a first-level voltage regulator U4, a second-level voltage regulator U1, a diode D1, and an optical signal outputter J1J2. The input end of the first-level voltage regulator U4 is connected to the output end of the power supply through the diode D1. The output end of the first-level voltage regulator U4 is connected to the input end of the second-level voltage regulator U1. The output end of the second-level voltage regulator U1 is connected to the optical signal outputter J1J2. The present utility model protects the input voltage by setting the diode D1, and the input voltage is double-regulated by the first-level voltage regulator U4 and the second-level voltage regulator U1 to ensure the output of the optical signal.

[0056] According to some embodiments of the present utility model, preferably, a resistor R11 is connected between the input end of the second-level voltage regulator U1 and the output end of the first-level voltage regulator U4. The present utility model sets the resistor R11 between the second-level voltage regulator U1 and the first-level voltage regulator U4 to play a role in current limiting.

[0057] According to some embodiments of the present utility model, preferably, the optical receiving circuit includes an optical signal inputter B1, a signal amplifier U2.1, a voltage comparator U2.2, and a signal outputter J1. The positive input end of the signal amplifier U2.1 is connected to the optical signal inputter B1. The negative input end of the voltage comparator U2.2 is connected to the output end of the signal amplifier U2.1. The positive input end of the voltage comparator U2.2 is connected to the output end of the first-level voltage regulator U4. The output end of the voltage comparator U2.2 is connected to the signal outputter J1. The present utility model sets an optical receiving circuit with an optical signal inputter B1, a signal amplifier U2.1, a voltage comparator U2.2, and a signal outputter J1. After the optical signal is input, it is amplified by the signal amplifier U2.1 and then compared by the voltage comparator U2.2 to form an output signal indicating whether an object is detected.

[0058] According to some embodiments of the present utility model, preferably, a resistor R3 and a capacitor C1 are connected between the output end of the signal amplifier U2.1 and the negative input end of the voltage comparator U2.2. A resistor R10 is connected between the output end of the voltage comparator U2.2 and the signal outputter J1. The present utility model sets the resistor R3 and the capacitor C1 between the signal amplifier U2.1 and the voltage comparator U2.2 to play a role in signal filtering; a resistor R10 is set between the voltage comparator U2.2 and the signal outputter J1 to play a role in current limiting.

[0059] According to some embodiments of the present utility model, preferably, a resistor R1 is connected to the negative input end of the signal amplifier U2.1 to play a role in the amplification factor.

[0060] According to some embodiments of the present invention, optionally, a resistor R5 is connected in parallel with the signal amplifier U2.1 to play a role in amplification factor.

[0061] According to some embodiments of the present invention, optionally, a resistor R2 and a capacitor C6 are connected to the positive input terminal of the signal amplifier U2.1 to play a role in signal filtering.

[0062] According to some embodiments of the present invention, optionally, resistors R4, R6, and R8 are connected to the voltage comparator U2.2 to be used for setting the comparison voltage feedback value.

[0063] Refer to Figures 2 - 3 , Figure 2 is a schematic diagram of the light beam path when no object is detected in some embodiments of the present invention; Figure 3 is a schematic diagram of the light beam path when an object is detected in some embodiments of the present invention.

[0064] According to some embodiments of the present invention, preferably, the detection principle of the present invention is specifically as follows:

[0065] The present invention emits a light beam to the platform 5 of the object to be measured. The platform 5 of the object to be measured will reflect the light beam back to the light receiving part 2, and then the control part 4 judges the intensity of the reflected light beam received by the light receiving part 2, and further judges whether the object 6 to be measured is detected.

[0066] When the light beam is emitted from the light emitting part 1 to the platform 5 of the object to be measured, and there is no object 6 to be measured on the platform 5 of the object to be measured, the light beam will be reflected by the platform 5 of the object to be measured and return to the light receiving part 2 through the light guiding channel 3. At this time, the control part 4 will output a low level;

[0067] When the light beam is emitted from the light emitting part 1 to the platform 5 of the object to be measured, and there is an object 6 to be measured on the platform 5 of the object to be measured, the light beam encounters the object 6 and is reflected by the object 6. At this time, the orbit of the reflected light beam is changed, so the strong light of the reflected light beam cannot enter the light guiding channel 3, while the weak light can enter the light guiding channel 3 and return to the light receiving part 2. At this time, the control part 4 will output a high level.

[0068] Refer to Figure 1 , Figure 1 is a schematic diagram of the structure of the object detection sensor in some embodiments of the present invention.

[0069] According to some embodiments of the present invention, preferably, the present invention also provides a detection method for an object detection sensor. The method is executed by the object detection sensor. The object detection sensor includes a light emitting part 1, a light receiving part 2, a light guiding channel 3, and a control part 4 having a light driving circuit, a light receiving circuit, and a power supply; the method includes

[0070] Emit a light beam, and drive the light emitting unit 1 to emit a light beam to the platform 5 of the object to be measured through the light driving circuit;

[0071] Receive the light beam. The light beam is reflected by the surface of the platform 5 of the object to be measured and passes through the light guiding channel 3 to the light receiving unit 2 to receive the light beam;

[0072] Output a level signal, convert the light beam signal into an electrical signal through the light receiving circuit and output a level signal.

[0073] In the present utility model, a light beam is emitted onto the platform 5 of the object to be measured. The platform 5 of the object to be measured will reflect the light beam back to the light receiving unit 2, and then the control unit 4 determines the intensity of the reflected light beam received by the light receiving unit 2, thereby determining whether the object 6 to be measured is detected.

[0074] When the light beam is emitted from the light emitting unit 1 to the platform 5 of the object to be measured and there is no object 6 to be measured on the platform 5 of the object to be measured, the light beam will be reflected by the platform 5 of the object to be measured and return to the light receiving unit 2 from the light guiding channel 3. At this time, the control unit 4 will output a low level;

[0075] When the light beam is emitted from the light emitting unit 1 to the platform 5 of the object to be measured and there is an object 6 to be measured on the platform 5 of the object to be measured, the light beam encounters the object 6 and is reflected by the object 6. At this time, the trajectory of the reflected light beam is changed, so the strong light of the reflected light beam cannot enter the light guiding channel 3, while the weak light can enter the light guiding channel 3 and return to the light receiving unit 2. At this time, the control unit 4 will output a high level.

[0076] It should be understood that the embodiments disclosed in the present utility model are not limited to the specific processing steps or materials disclosed herein, but should extend to equivalent alternatives of such features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and do not mean limitation.

[0077] The "embodiments" mentioned in the specification mean that the specific features or characteristics described in connection with the embodiments are included in at least one embodiment of the present utility model. Therefore, the phrase "embodiments" that appears throughout the specification does not necessarily refer to the same embodiment.

[0078] In addition, the described features or characteristics can be combined into one or more embodiments in any other suitable manner. In the above description, some specific details, such as thickness, quantity, etc., are provided to provide a comprehensive understanding of the embodiments of the present utility model. However, those skilled in the relevant art will understand that the present utility model can be implemented without one or more of the above specific details or can also be implemented using other methods, components, materials, etc.

Claims

1. An object detection sensor, characterized in that: It includes a light emitting part, a light guiding channel, a light receiving part and a control part. A light emitting unit, which is used to emit a light beam to the platform of the object to be measured; A light receiving unit, which is used to receive a portion of the reflected light beam from the platform of the object to be measured; A light guiding channel, used for guiding part of the reflected light beam of the platform of the object to be measured to the light receiving part; The control unit is connected to the light emitting unit and the light receiving unit respectively and is used to control the photoelectric signal conversion between the light emitting unit and the light receiving unit.

2. The object detection sensor according to claim 1, characterized in that: The central axis of the light-guiding channel is axially symmetrical with the light beam emission central axis of the light-emitting portion and intersects with each other.

3. The object detection sensor according to claim 1, characterized in that: The length of the light guiding channel is at least 5 mm.

4. The object detection sensor according to claim 1, characterized in that: The light guiding channel is a non-transparent channel.

5. The object detection sensor according to claim 1, characterized in that: The control unit includes an optical driving circuit, an optical receiving circuit and a power supply. The optical driving circuit is used to drive the optical emitting unit to emit an optical signal, the optical receiving circuit is used to control the optical receiving unit to receive an optical signal, and the power supply provides electrical energy to the optical driving circuit and the optical receiving circuit.

6. The object detection sensor according to claim 5, characterized in that: The optical driving circuit includes a primary voltage regulator, a secondary voltage regulator, a diode, and an optical signal output device. The input end of the primary voltage regulator is connected to the output end of the power supply through the diode, the output end of the primary voltage regulator is connected to the input end of the secondary voltage regulator, and the output end of the secondary voltage regulator is connected to the optical signal output device.

7. The object detection sensor according to claim 6, characterized in that: A resistor is connected between the input end of the secondary regulator and the output end of the primary regulator.

8. The object detection sensor according to claim 6, characterized in that: The optical receiving circuit includes an optical signal input device, a signal amplifier, a voltage comparator, and a signal output device. The positive input terminal of the signal amplifier is connected to the optical signal input device, the negative input terminal of the voltage comparator is connected to the output terminal of the signal amplifier, the positive input terminal of the voltage comparator is connected to the output terminal of the primary regulator, and the output terminal of the voltage comparator is connected to the signal output device.

9. The object detection sensor according to claim 8, characterized in that: A resistor is connected between the output end of the signal amplifier and the negative input end of the voltage comparator, and a resistor is connected between the output end of the voltage comparator and the signal outputter.

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