A metal detection device suitable for testing various products

By switching the emitter resistor, feedback loop resistor and transformer tap, and configuring multiple receiver transformers and demodulation circuits, the problem of existing metal detectors being difficult to adapt to multiple product testing is solved, and efficient detection and precise matching of multiple products is achieved .

CN113092532BActive Publication Date: 2024-12-27TECHIK INSTR SHANGHAI
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Patent Information

Application Number
CN202110496250.9
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2021-05-07
Publication Date
2024-12-27
Estimated Expiration
2041-05-07

AI Technical Summary

Technical Problem

Existing metal detectors are difficult to adapt to the testing of many different types of products, because a single metal detector cannot match the optimal detection circuit of different products, resulting in a decrease in detection accuracy when the magnetic field strength changes, and metal interferers are difficult to detect.

Method used

By switching the emitter resistor, the overall feedback loop resistor and the transformer tap, multiple receiving transformer and demodulation circuits are configured to achieve optimal matching and outputs of different powers, and adapt to the testing of multiple products.

Benefits of technology

It realizes effective detection of a variety of products, improves detection accuracy and adaptability, and ensures the metal detection effect under different magnetic field conditions.

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Abstract

The present invention relates to a metal detection device suitable for testing multiple products. The metal detection device is designed with an adjustable power circuit, an adjustable receiving circuit, and multiple demodulation circuits to adapt to multiple product testing and achieve the best detection accuracy. The overall circuit scheme is controlled by a host computer to adjust the output power of the power drive circuit, thereby changing the strength of the magnetic field of the detection system, and switching the transformer and amplification circuit of the receiving circuit to achieve the matching of the receiving coil with the demodulation circuit under different power states. The demodulation circuit structure is adjusted to achieve the best detection effect suitable for different products.
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Description

Technical Field

[0001] The invention relates to the field of metal detectors, and in particular to a metal detection device suitable for testing a variety of products. Background Art

[0002] In the actual use scenarios of metal detectors, there are often different types of products on a production line, and these products have different characteristics. This requires the metal detector to be able to adapt to the testing of multiple different types of products at the same time.

[0003] In a metal detector, the coil system, power drive circuit, and receiving demodulation circuit together constitute a system. Each circuit parameter must match each other to achieve the best accuracy. When one of them changes, the corresponding other parameters must be adjusted accordingly to ensure good test results.

[0004] Different products have different optimal detection circuits. For example, products with large product effects are more suitable for detection in stronger magnetic fields. If the magnetic field is weak, the metal interference inside the product can be easily "shielded" by the product effect. The change in the strength of the magnetic field requires the change of the power drive circuit. The change in the power drive circuit requires the adjustment of the receiving demodulation circuit to match it. Therefore, in the prior art, a single metal detector is often unable to adapt to multiple different types of products. Summary of the invention

[0005] The purpose of the present invention is to provide a metal detection device suitable for testing a variety of products. By switching the emitter resistance, the overall feedback loop resistance, and the transformer tap, the best matching and the output of different powers are achieved, and the switching of multiple receiving transformers and the switching of demodulation circuits are configured to match them, the testing of a variety of products can be realized.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A metal detection device suitable for testing a variety of products, including:

[0008] A power drive circuit and a transmitting coil connected to each other;

[0009] A receiving coil, a receiving circuit and a demodulation circuit connected in sequence;

[0010] The power driving circuit includes a signal input end, a first feedback resistor module, a second feedback resistor module, a three-stage amplifier circuit, an emitter resistor module and a multi-tap transformer, the input end of the three-stage amplifier circuit is connected to the signal input end, the output end is connected to the input end of the multi-tap transformer through the emitter resistor module, the output end of the multi-tap transformer is connected to the transmitting coil, the three-stage amplifier circuit includes a differential amplifier stage, a voltage amplifier stage and a current amplifier stage connected in sequence, the emitter resistor module is composed of a plurality of emitter resistors connected in parallel, one end of each emitter resistor is connected to the input end of the multi-tap transformer, and the other end is connected to the three-stage amplifier circuit through a first switching switch, the first feedback resistor module is composed of a plurality of first feedback resistors, one end of each first feedback resistor is grounded, and the other end is connected to the differential amplifier stage and the second feedback resistor module through a second switching switch, the second feedback resistor module is composed of a plurality of second feedback resistors, one end of each second feedback resistor is connected to the second switching switch, and the other end is connected to the input end of the multi-tap transformer through a third switching switch;

[0011] The receiving circuit includes a receiving transformer and a receiving amplifier, wherein a plurality of receiving transformers are provided, and an input end of each receiving transformer is connected to the receiving coil through a fourth switching switch, and an output end is connected to the receiving amplifier;

[0012] The demodulation circuit includes a square wave demodulation circuit and a sine wave demodulation circuit, and input ends of the square wave demodulation circuit and the sine wave demodulation circuit are connected to the receiving circuit through a fifth switching switch.

[0013] The three-stage amplifier circuit and the emitter resistor module are each provided with two.

[0014] A sixth switch is provided at the input end of the multi-tap transformer.

[0015] The first switch, the second switch, the third switch and the sixth switch are all relays.

[0016] The fourth switch is a relay.

[0017] The fifth switching switch is a relay.

[0018] The number of first feedback resistors in the first feedback resistor module is 2, and the number of second feedback resistors in the second feedback resistor module is 2.

[0019] The number of emitter resistors in the emitter resistor module is 2.

[0020] There are two receiving transformers in total.

[0021] The device also includes a host computer, and the first switch, the second switch, the third switch, the fourth switch and the fifth switch are all connected to the host computer.

[0022] Compared with the prior art, the present invention has the following beneficial effects: by switching the emitter resistance, the overall feedback loop resistance, and the transformer taps, optimal matching and output of different powers are achieved, and the switching of multiple receiving transformers and the switching of demodulation circuits are configured to match them, so that the testing of various products can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the power driving circuit of the present invention;

[0024] Figure 2 It is a structural schematic diagram of a receiving circuit of the present invention;

[0025] Figure 3 is a schematic diagram of a first demodulation circuit of the present invention;

[0026] Figure 4 It is a schematic diagram of a second demodulation circuit of the present invention. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0028] A metal detection device suitable for testing a variety of products, including:

[0029] A power drive circuit and a transmitting coil connected to each other;

[0030] A receiving coil, a receiving circuit and a demodulation circuit connected in sequence;

[0031] like Figure 1As shown, the power drive circuit includes a signal input end, a first feedback resistor module, a second feedback resistor module, a three-stage amplifier circuit, an emitter resistor module and a multi-tap transformer, the input end of the three-stage amplifier circuit is connected to the signal input end, the output end is connected to the input end of the multi-tap transformer through the emitter resistor module, the output end of the multi-tap transformer is connected to the transmitting coil, the three-stage amplifier circuit includes a differential amplifier stage, a voltage amplifier stage and a current amplifier stage connected in sequence, the emitter resistor module is composed of a plurality of emitter resistors connected in parallel, one end of each emitter resistor is connected to the input end of the multi-tap transformer, and the other end is connected to the three-stage amplifier circuit through a first switching switch, the first feedback resistor module is composed of a plurality of first feedback resistors, one end of each first feedback resistor is grounded, and the other end is connected to the differential amplifier stage and the second feedback resistor module through a second switching switch, the second feedback resistor module is composed of a plurality of second feedback resistors, one end of each second feedback resistor is connected to the second switching switch, and the other end is connected to the input end of the multi-tap transformer through a third switching switch;

[0032] The power drive circuit is designed as a three-stage amplifier circuit, the first stage is a differential amplifier stage, the second stage is a voltage amplifier stage, and the third stage is a current amplifier stage. The best matching and different power outputs can be achieved by switching the emitter resistance of the current amplifier stage, the overall feedback loop resistance, and the transformer tap.

[0033] like Figure 2 As shown, the receiving circuit includes a receiving transformer and a receiving amplifier. There are multiple receiving transformers, and the input end of each receiving transformer is connected to the receiving coil through a fourth switching switch, and the output end is connected to the receiving amplifier; the receiving circuit is a transformer and a receiving amplifier with adjustable amplification gain. The characteristic of the receiving circuit is that the signal of the receiving coil can be received into a subsequent demodulation circuit through two different types of transformers. The characteristics of the two transformers are different, and the two transformers are used to match the high power mode and the low power mode respectively.

[0034] like Figure 3 and Figure 4 As shown, the demodulation circuit includes a square wave demodulation circuit and a sine wave demodulation circuit, and the input ends of the square wave demodulation circuit and the sine wave demodulation circuit are connected to the receiving circuit through a fifth switching switch. There are two types of demodulation circuits, which are respectively composed of two demodulation circuits with square wave carrier signals and sine wave carrier signals. The subsequent filtering and amplification circuits of the two demodulation circuits are different. The subsequent signal processing circuit is designed according to the different noise characteristics of the two demodulation circuits. The characteristics of the two demodulation structures are applied, and reasonable switching is performed to meet the needs of different applications and achieve the best detection results.

[0035] In some embodiments, two of each of the three-stage amplifier circuit and the emitter resistor module are provided.

[0036] In some embodiments, a sixth switching switch is provided at the input end of the multi-tap transformer, the first switching switch, the second switching switch, the third switching switch and the sixth switching switch are all relays, the fourth switching switch is a relay, and the fifth switching switch is a relay. The device also includes a host computer, and the first switching switch, the second switching switch, the third switching switch, the fourth switching switch and the fifth switching switch are all connected to the host computer, with high reliability.

[0037] In some embodiments, the number of first feedback resistors in the first feedback resistor module is 2, the number of second feedback resistors in the second feedback resistor module is 2, the number of emitter resistors in the emitter resistor module is 2, and there are two receiving transformers in total.

Claims

1. A metal detection device suitable for testing a variety of products, comprising: A power drive circuit and a transmitting coil connected to each other; A receiving coil, a receiving circuit and a demodulation circuit connected in sequence; It is characterized in that The power driving circuit includes a signal input end, a first feedback resistor module, a second feedback resistor module, a three-stage amplifier circuit, an emitter resistor module and a multi-tap transformer, the input end of the three-stage amplifier circuit is connected to the signal input end, the output end is connected to the input end of the multi-tap transformer through the emitter resistor module, the output end of the multi-tap transformer is connected to the transmitting coil, the three-stage amplifier circuit includes a differential amplifier stage, a voltage amplifier stage and a current amplifier stage connected in sequence, the emitter resistor module is composed of a plurality of emitter resistors connected in parallel, one end of each emitter resistor is connected to the input end of the multi-tap transformer, and the other end is connected to the three-stage amplifier circuit through a first switching switch, the first feedback resistor module is composed of a plurality of first feedback resistors, one end of each first feedback resistor is grounded, and the other end is connected to the differential amplifier stage and the second feedback resistor module through a second switching switch, the second feedback resistor module is composed of a plurality of second feedback resistors, one end of each second feedback resistor is connected to the second switching switch, and the other end is connected to the input end of the multi-tap transformer through a third switching switch; The receiving circuit includes a receiving transformer and a receiving amplifier, wherein a plurality of receiving transformers are provided, and an input end of each receiving transformer is connected to the receiving coil through a fourth switching switch, and an output end is connected to the receiving amplifier; The demodulation circuit includes a square wave demodulation circuit and a sine wave demodulation circuit, and input ends of the square wave demodulation circuit and the sine wave demodulation circuit are connected to the receiving circuit through a fifth switching switch.

2. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: The three-stage amplifier circuit and the emitter resistor module are each provided with two.

3. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: A sixth switch is provided at the input end of the multi-tap transformer.

4. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: The first switch, the second switch, the third switch and the sixth switch are all relays.

5. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: The fourth switch is a relay.

6. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: The fifth switching switch is a relay.

7. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: The number of first feedback resistors in the first feedback resistor module is 2, and the number of second feedback resistors in the second feedback resistor module is 2.

8. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: The number of emitter resistors in the emitter resistor module is 2.

9. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: There are two receiving transformers in total.

10. A metal detection device suitable for testing a variety of products according to claim 1, characterized in that: The device also includes a host computer, and the first switch, the second switch, the third switch, the fourth switch and the fifth switch are all connected to the host computer.