Test pencil

Abstract

The utility model relates to the technical field of electrical measurement, in particular to a test pencil, which comprises a pencil-shaped shell, an induction unit, a selection unit, a detection circuit and a display unit, wherein the pen-shaped shell is hollow; the sensing unit is arranged at the front end of the pen-shaped shell, extends into the pen-shaped shell, is connected with the detection circuit and is used for acquiring a voltage signal and outputting the voltage signal to the detection circuit; the selection unit is arranged on the outer surface of the pen-shaped shell, is connected with the detection circuit and is used for outputting a reference signal corresponding to a corresponding function to the detection circuit based on the function of the test pencil selected by a user; and the detection circuit is used for comparing the voltage signal with a reference signal, outputting a detection result and sending the detection result to the display unit for display. According to the test pencil, the electric field intensity of a tested object can be accurately identified, and accurate identification of a null line and a live line can be realized in various scenes.

Description

Technical Field

[0001] The utility model relates to the technical field of electrical measurement, in particular to an electric test pencil. Background Art

[0002] At present, traditional non-contact electric testers determine whether the object is charged by detecting the electric field of the object being tested, and they cannot show the strength of the induced electric field. What's worse, in some special scenarios, such as when the live wire and the neutral wire of the object being tested are very close, this type of electric tester is prone to missed detection and cannot accurately distinguish between the neutral wire and the live wire.

[0003] In summary, the existing electric tester has a single function, cannot effectively detect the strength of the induced electric field, and is difficult to accurately identify the neutral wire and the live wire. Utility Model Content

[0004] Therefore, in order to overcome the existing problems, the utility model provides an electric tester, which can accurately identify the electric field strength of the object being tested and can achieve accurate identification of the neutral wire and the live wire in various scenarios.

[0005] In order to achieve the above object, the utility model provides the following technical solutions:

[0006] The utility model provides an electric test pen, which includes a pen-shaped housing 1, a sensing unit 2 and a display unit 5, wherein the pen-shaped housing 1 is hollow, and the electric test pen further includes:

[0007] Selection unit 3 and detection circuit 4;

[0008] The sensing unit 2 is disposed at the front end of the pen-shaped housing 1 and extends into the pen-shaped housing 1 to be connected to the detection circuit 4, and is used to obtain a voltage signal and output the voltage signal to the detection circuit 4;

[0009] The selection unit 3 is disposed on the outer surface of the pen-shaped housing 1 and connected to the detection circuit 4, and is used to output a reference signal corresponding to the corresponding function to the detection circuit 4 based on the function of the electric test pen selected by the user;

[0010] The detection circuit 4 is used to compare the voltage signal with the reference signal, output the detection result and send it to the display unit 5 for display.

[0011] The electric test pen provided by the utility model includes: a pen-shaped shell, a sensing unit, a selection unit, a detection circuit and a display unit; wherein the pen-shaped shell is hollow; the sensing unit is arranged at the front end of the pen-shaped shell and extends into the pen-shaped shell to be connected to the detection circuit, for obtaining a voltage signal and outputting the voltage signal to the detection circuit; the selection unit is arranged on the outer surface of the pen-shaped shell and connected to the detection circuit, for outputting a reference signal corresponding to the corresponding function to the detection circuit based on the function of the electric test pen selected by the user; the detection circuit is used to compare the voltage signal with the reference signal, output the detection result and send it to the display unit for display. Through the electric test pen of the utility model, the electric field strength of the object being tested can be accurately identified, and the accurate identification of the neutral and live wires can be achieved in various scenarios.

[0012] Optionally, the selection unit 3 includes a key circuit 31 and a multiplexer 32;

[0013] The multiplexer 32 is connected to the key circuit 31 and the detection circuit 4 respectively, determines the function of the tester based on the output of the key circuit 31 and outputs a reference signal corresponding to the corresponding function.

[0014] The utility model determines the test pen function selected by the user and the reference signal corresponding to the function based on the key circuit and the multiplexer of the selection unit, and can use the test pen more flexibly based on the actual use needs of the user, which helps to improve the user experience.

[0015] Optionally, the detection circuit 4 includes a plurality of subtraction circuits 41;

[0016] Each subtraction circuit 41 is connected to the demultiplexer 32 respectively, and is used for subtracting the reference signal output by the demultiplexer 32 from the voltage signal to obtain a detection result, and sending the detection result to the display unit 5 for display.

[0017] The utility model realizes the recognition of voltage signals under different functions of the electric tester based on multiple subtraction operation circuits, and can ensure the accurate recognition of the electric field strength or the neutral and live wires of the object to be tested.

[0018] Optionally, the electric tester further comprises:

[0019] Amplifying circuit 6, filtering circuit 7 and power supply unit 8;

[0020] The amplifying circuit 6 is connected to the sensing unit 2 and the filtering circuit 7 respectively, and is used to obtain the voltage signal of the sensing unit 2, and amplify the voltage signal and send it to the filtering circuit 7;

[0021] The filter circuit 7 is connected to the multiple subtraction circuits 41 respectively, and is used to filter the voltage signal and send it to each subtraction circuit 41 respectively;

[0022] The power supply unit 8 is embedded in the pen-shaped housing 1 and is respectively connected to the detection circuit 4 and the display unit 5 for providing electric energy.

[0023] Optionally, the display unit 5 includes: a buzzer 51 and / or an indicator light 52 .

[0024] Optionally, the sensing unit 2 includes: a sensing probe 21 and a sensing antenna 22 .

[0025] Optionally, the power supply unit 8 is a rechargeable lithium battery.

[0026] Optionally, the indicator light 52 is an LED light.

[0027] Optionally, the sensing probe 21 is made of polymer nano-magnetic sensitive material. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of an electric test pencil according to an embodiment of the utility model;

[0030] Figure 2 It is a structural schematic diagram of another electric test pencil according to an embodiment of the utility model;

[0031] Figure 3 It is the circuit schematic diagram of the microcontroller;

[0032] Figure 4 is a structural schematic diagram of a precise distinction mode according to an embodiment of the utility model;

[0033] Figure 5 is a structural schematic diagram of a security differentiation mode according to an embodiment of the utility model;

[0034] Figure 6 It is a logic diagram of various modes of the electric tester according to an embodiment of the utility model;

[0035] Figure 7 It is the circuit schematic diagram of the induction antenna;

[0036] Figure 8 It is the circuit schematic diagram of the key circuit;

[0037] Fig. 9 This is the circuit diagram of the LED lamp;

[0038] Fig.10 This is the circuit diagram of the buzzer.

[0039] Description of reference numerals:

[0040] 1. Pen-shaped housing; 2. Sensing unit; 21. Sensing probe; 22. Sensing antenna; 3. Selection unit; 31. Key circuit; 32. Multiplexer; 4. Detection circuit; 41. Subtraction circuit; 5. Display unit; 51. Buzzer; 52. Indicator light; 6. Amplifying circuit; 7. Filtering circuit; 8. Power supply unit. DETAILED DESCRIPTION

[0041] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0042] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are 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 cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0044] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] The utility model provides an electric test pencil. Figure 1 Schematic diagram of the structure of the electric tester according to the embodiment of the utility model. Figure 1As shown, the structure includes: a pen-shaped housing 1, a sensing unit 2, a selection unit 3, a detection circuit 4 and a display unit 5.

[0046] The pen-shaped housing 1 of the electric tester of the present utility model is hollow and made of ABS plastic. It should be noted that ABS plastic is a widely used thermoplastic engineering plastic with excellent impact resistance, heat resistance, low temperature resistance, chemical resistance and electrical properties. It also has the advantages of easy processing, stable product size, good surface gloss, easy coating and coloring, and can be subjected to secondary processing such as surface metallization, electroplating, welding, hot pressing and bonding, and is widely used in industrial fields such as machinery, automobiles, electronic appliances, instruments and meters, textiles and construction.

[0047] In the embodiment of the utility model, the sensing unit 2 is arranged at the front end of the pen-shaped housing 1 and extends into the pen-shaped housing 1 to be connected to the detection circuit 4, and is used to obtain the voltage signal and output the voltage signal to the detection circuit 4. Specifically, by setting the sensing unit 2, the voltage signal can be sensed in time and automatically collected, which effectively improves the acquisition accuracy and efficiency of the voltage signal.

[0048] In the embodiment of the utility model, the selection unit 3 is arranged on the outer surface of the pen-shaped housing 1 and connected to the detection circuit 4, and is used to output a reference signal corresponding to the corresponding function to the detection circuit 4 based on the function of the test pen selected by the user. It should be noted that the reference signal in the embodiment of the utility model is the voltage signal corresponding to the test pen under different functions, and its specific value is not limited here, and can be adaptively adjusted based on actual application requirements.

[0049] In the embodiment of the utility model, the detection circuit 4 is used to compare the voltage signal with the reference signal, output the detection result and send it to the display unit 5 for display. It should be noted that the specific type and number of the detection circuit 4 in the embodiment of the utility model are not limited here, and can be adaptively adjusted based on actual needs. For example, the detection circuit 4 is a comparator circuit, a subtraction circuit, or a single-chip microcomputer integrating multiple operation circuits, etc., which is only used as an exemplary description.

[0050] The electric tester of the embodiment of the utility model can realize different electric tester functions by only adding a sensing unit 2, a selection unit 3 and a detection circuit 4 on the basis of the existing electric tester. It has the advantages of simple design, convenient carrying and use, and can not only accurately identify the electric field strength of the object under test, but also realize accurate identification of the neutral wire and the live wire in various scenarios, which greatly reduces the function detection cost of the electric tester.

[0051] The utility model provides an electric test pencil. Figure 2 2 is a schematic diagram of the structure of another test pencil according to an embodiment of the utility model. Figure 2As shown, the structure includes: a pen-shaped housing 1, a sensing unit 2, a selection unit 3, a detection circuit 4 and a display unit 5.

[0052] In the embodiment of the utility model, the sensing unit 2 includes: a sensing probe 21 and a sensing antenna 22, wherein the sensing probe 21 is a polymer nano-magnetic material, which has high magnetic permeability and electrical conductivity, and can detect the voltage intensity of the induction voltage in a non-contact manner, and can also test the voltage value of the circuit in a contact manner. It should be noted that the specific material of the sensing antenna 22 is not limited here, and can be adaptively selected according to actual needs. For example, the sensing antenna 22 is an aluminum sheet antenna or a combination circuit of an I-shaped inductor and a transistor, wherein the aluminum sheet antenna can sense the electromagnetic field and output a corresponding electrical signal; one end of the I-shaped inductor is connected to the base of the transistor, and the other end is suspended. When the inductor is close to the live wire, a weak current will be induced, and the corresponding electrical signal obtained after multi-stage amplification by the transistor is sent to the subsequent display unit 5 for display, such as lighting up the LED 52 to make the buzzer 51 sound, thereby identifying the corresponding neutral and live wires.

[0053] In the embodiment of the utility model, the selection unit 3 includes a key circuit 31 and a multiplexer 32; wherein the multiplexer 32 is connected to the key circuit 31 and the detection circuit 4 respectively, determines the function of the electric tester based on the output of the key circuit 31 and outputs a reference signal corresponding to the corresponding function. It should be noted that the specific types of the key circuit 31 and the multiplexer 32 in the utility model are not limited here, and are adaptively adjusted based on actual needs. Specifically, the key circuit 31 is a multi-function key, and the corresponding electric tester function is selected by the number of key presses. For example, the initial mode of the multi-function key is the power search mode, followed by the precise distinction mode and the safe distinction mode. Each press of the key corresponds to switching to the next mode (i.e., a different electric tester function), and the electric tester function is cyclically selected by different key presses. It should be noted that the multiplexer 32 is also called a data distributor, which is a circuit that can transmit an input data to any one of multiple output terminals as needed. It includes 1-way to 4-way data distributors (such as 74LS139), 1-way to 8-way data distributors (such as 74LS138), etc. The specific number of output terminals can also be adaptively selected based on actual needs.

[0054] In an embodiment of the utility model, the detection circuit 4 includes multiple subtraction circuits 41; wherein each subtraction circuit 41 is respectively connected to the multiplexer 32, and is used to subtract the reference signal output by the multiplexer 32 from the voltage signal to obtain a detection result, and send the detection result to the display unit 5 for display.

[0055] In an embodiment of the utility model, the subtraction circuit 41 is used to subtract the voltage signal from the reference voltage to obtain a corresponding detection result, and send the detection result as an indication signal to the display unit 5, the indication signal includes a first signal and a second signal, wherein the first signal is a difference result of zero; the second signal is a difference result of non-zero.

[0056] In a specific embodiment, the subtraction circuit 41 has two input signals, namely, the collected voltage signal and the reference voltage; the two input signals are connected to the operational amplifier through two resistors. When the difference between the voltage signal and the reference voltage is zero, the subtraction circuit 41 outputs a low-level signal, i.e., the first signal; when the difference between the voltage signal and the reference voltage is not zero, the subtraction circuit 41 outputs a high-level signal, i.e., the second signal, which is only used as an example.

[0057] In the embodiment of the utility model, the display unit 5 is used to display the detection result when the indication signal is the second signal. Specifically, the display unit 5 includes: a buzzer 51 and / or an indicator light 52, wherein the indicator light 52 is an LED light.

[0058] In a specific embodiment, when the electric tester is performing the function of identifying the neutral wire and the live wire, for the object under test, if the subtraction circuit 41 outputs a high-level signal, the object under test is a live wire at this time, and the buzzer 51 is controlled to sound long and / or the LED indicator 52 is always on, so as to display the result that the object under test is a live wire. Or the LED indicator 52 is controlled to light up different colors to indicate the detection result of the object under test, such as green for the neutral wire and red for the live wire. This is only used as an example and is not limited to this. Adaptive modifications can be made according to actual needs. It should be noted that the buzzer 51 can adopt an integrated active buzzer TMB12A12; the control implementation method of the buzzer 51 and the indicator 52 is a relatively mature program setting in the prior art, which will not be described in detail here.

[0059] In an embodiment of the utility model, the electric test pen also includes: an amplifier circuit 6, a filter circuit 7 and a power supply unit 8; wherein the amplifier circuit 6 is respectively connected to the sensing unit 2 and the filter circuit 7, for obtaining the voltage signal of the sensing unit 2, and amplifying the voltage signal and sending it to the filter circuit 7; the filter circuit 7 is respectively connected to multiple subtraction circuits 41, for filtering the voltage signal and sending it to each subtraction circuit 41; the power supply unit 8 is embedded in the pen-shaped housing 1 and is respectively connected to the detection circuit 4 and the display unit 5, for providing electrical energy.

[0060] It should be noted that the amplifier circuit 6 in the embodiment of the utility model is an amplifier commonly used in the art, and the filter circuit 7 is a filter commonly used in the art. The specific types of the amplifier and the filter are not limited here and are adaptively adjusted according to actual needs.

[0061] In a specific embodiment, the power supply unit 8 is a rechargeable lithium battery, model 18650, which is only used as an example and can be adaptively modified according to actual needs.

[0062] In a specific embodiment, the electric tester of the utility model embodiment is designed with three functions (or modes), namely, the power-seeking mode, the precise distinction mode and the safety distinction mode. Among them, the power-seeking mode realizes the power-seeking function of different power supply strengths according to the distance between the electric tester and the AC power supply, that is, realizes the precise identification of the electric field strength corresponding to different AC voltage ranges. The precise distinction mode and the safety distinction mode are both for the identification of the neutral and live wires, wherein the application scenario of the precise distinction mode is the case where the distance between the wires is small, such as being used to determine the specific position of the neutral and live wires in the wire without stripping the wires of the object being tested; the application scenario of the safety distinction mode is the case where the distance between the wires is large. The display unit 5 of the utility model embodiment includes a buzzer TMB12A12 and 6 LED indicator lights 52, and the 6 LEDs are represented by D1 to D6 respectively, wherein the LEDs D1 to D5 work in the power-seeking mode, and are used to display the test results of the electric tester in the power-seeking mode; the LED D6 works in the precise distinction mode and the safety distinction mode, and is used to display the test results of the electric tester in the precise distinction mode and the safety distinction mode. The detection circuit 4 of the embodiment of the utility model is a single chip microcomputer integrating multiple operation circuits. The circuit schematic diagram of the single chip microcomputer is shown in FIG. Figure 3 By using the electric tester of the present invention to perform various function tests, the specific process includes:

[0063] Step A1: Data mean processing.

[0064] In this embodiment, the voltage signal induced by the antenna at the head of the tester is amplified by an amplifier, and then read and processed by the analog-to-digital converter (ADC) of the single-chip computer, wherein the data is read once every 5ms, and the average value is taken every 100 times, and the average value is used as the basis for subsequent function judgment. The specific process of data processing is: after the ADC reads the data 12 times, the data is subjected to median average filtering and Kalman filtering operations, and the process is repeated 50 times, the maximum and minimum values ​​of the data are found, and the difference between the above two data is calculated; the above process is then repeated 10 times to obtain 10 difference results and the average value is solved to obtain the average value corresponding to the data.

[0065] Step A2: Function test of the voltage tester.

[0066] In this embodiment, when the electric tester is in the electricity-seeking mode, the average value is compared with 5 threshold values ​​through the subtraction circuit integrated in the single-chip microcomputer, and the results are displayed through the 5 LED lights that light up on the display unit 5 and the buzzer TMB12A12 that sounds at different frequencies. It should be noted that the 5 threshold values ​​correspond to 5 different electric field strengths, and the strongest AC source nearby can be found based on the number of LED lights that light up and the frequency of the buzzer TMB12A12. It should be noted that the specific values ​​of the 5 threshold values ​​in this embodiment are not limited here, and are determined based on multiple measurements and analysis of the antenna placed in the corresponding scene during the actual debugging process. Specifically, the setting of 5 threshold values ​​expands the range of electric field strength that can be detected by the electric tester, and reduces the occurrence of missed detection of charged objects (i.e., the situation where the live wire and the neutral wire of the charged object are very close) to a certain extent.

[0067] In this embodiment, when the test pen is in the precise distinction mode, the average value is compared with a higher threshold value (such as the threshold value corresponding to the sensing distance of 3mm) through the subtraction circuit integrated in the single-chip microcomputer. When it is higher than this threshold value, all five LED lights are on and the buzzer TMB12A12 sounds; when it is lower than this threshold value, all five LED lights are off and the buzzer TMB12A12 does not sound. It should be noted that the corresponding threshold value is designed to be relatively high in the precise distinction mode because it can only be higher than the threshold value when the antenna is within 3mm of the live wire (i.e., when the live wire and the neutral wire of the charged object are very close). Figure 4 is a structural diagram of the precise distinction mode according to an embodiment of the utility model, comprising Figure 4 It can be seen that the live wire and the neutral wire are very close to each other. When the tester is placed from the direction 1 side to identify the live wire and the neutral wire, the LED light and the buzzer TMB12A12 both work normally. However, when the tester is placed from the direction 2 side and the direction 3 side to identify the live wire and the neutral wire, the LED light and the buzzer TMB12A12 do not work.

[0068] In this embodiment, when the voltage tester is in the safety distinction mode, the average value is compared with a lower threshold value (such as a threshold value corresponding to a sensing distance of 15 mm) through the subtraction circuit integrated in the single-chip microcomputer. When it is higher than this threshold value, all five LED lights are on and the buzzer TMB12A12 sounds; when it is lower than this threshold value, all five LED lights are off and the buzzer TMB12A12 does not sound. Figure 5 Schematic diagram of the structure of the security distinction mode according to the embodiment of the utility model. Figure 5 It can be seen that in the safety distinction mode, the two wires are separated by a sufficient distance, that is, the live wire and the neutral wire are relatively far away. The electric tester of this embodiment can distinguish the live and neutral wires of the object being tested even if it is far away from the wires, making the operation safer and ensuring the safety of the operator.

[0069] In this embodiment, Figure 6This is a logic diagram of each mode of the electric tester according to an embodiment of the utility model. Specifically, the electric tester of this embodiment can light up 5 indicator lights according to the distance from the AC power supply to realize the power search function, increase the range of AC voltage that can be measured, and greatly reduce the occurrence of missed detection. In addition, in order to accurately distinguish the neutral and live wires of the object under test, the function of switching sensitivity mode (i.e., precise distinction mode and safe distinction mode) is added to achieve accurate identification of the neutral and live wires in different scenarios.

[0070] In this embodiment, the pins of the single-chip microcomputer are connected to the remaining circuits of the remaining test pens, so as to realize the sending and receiving of corresponding signals. Figure 7 is the circuit schematic of the inductive antenna, consisting of Figure 7 It can be seen that ANT1 is an antenna, which can sense voltage signals of different strengths according to the strength of the AC electric field; U2 is an operational amplifier, which amplifies the voltage signal induced on the antenna and connects it to the ADC pin of the microcontroller through AIN3, that is, the change in the value of the microcontroller ADC is used to reflect the change in the induced electric field strength. Figure 8 This is the circuit diagram of the key circuit, consisting of Figure 8 It can be seen that the functions of the tester can be selected by connecting PC7 to the corresponding pins of the microcontroller. Fig. 9 This is the circuit diagram of the LED lamp. Fig. 9 It can be seen that the LED lights corresponding to D1-D5 (lights indicating the distance to the AC power supply, the closer to the AC power supply, the more lights are on) are connected to the corresponding pins of the single-chip computer through PA3, PC5, PC6, PC3 and PD3 respectively to realize the display of the results of the power-seeking mode of the test pen; the LED light corresponding to D6 (light indicating the sensitivity mode) is connected to the corresponding pin of the single-chip computer through PC4 to realize the display of the corresponding results of the precise distinction mode and the safe distinction mode of the test pen. Specifically, the single-chip computer controls the on and off of the six LED lights D1-D6 by setting the high and low levels of the corresponding pins. Fig.10 This is the circuit diagram of the buzzer. Fig.10 It can be seen that the BEEP pin is connected to the corresponding pin of the microcontroller to display the results of each function of the test pencil.

[0071] In a specific embodiment, when the voltage tester reaches different thresholds T in the voltage search mode, the states of the LED lights corresponding to D1-D5 and the frequencies of the buzzers are shown in Table 1:

[0072] Table 1

[0073]

[0074] It should be noted that, when the voltage tester is in the precise distinction mode or the safe distinction mode, there is only one threshold value corresponding to its value, that is, the corresponding LED lights D1-D5 in the electricity-seeking mode can be on or off at the same time (without affecting the detection results of the voltage tester in the precise distinction mode and the safe distinction mode). The corresponding live wire identification detection result is only displayed by indicating the light status of LED light D6 in the sensitivity mode and the buzzer ringing at a frequency of 4khz.

[0075] In summary, the electric tester provided by the utility model can accurately identify the electric field strength of the object being tested, and can also achieve accurate identification of the neutral wire and the live wire in various scenarios.

[0076] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention of the utility model.

Claims

1. An electric test pen, comprising a pen-shaped housing (1), a sensing unit (2) and a display unit (5), wherein the pen-shaped housing (1) is hollow, and characterized in that: The electric tester also includes: A selection unit (3) and a detection circuit (4); The sensing unit (2) is arranged at the front end of the pen-shaped housing (1) and extends into the pen-shaped housing (1) to be connected to the detection circuit (4), and is used to obtain a voltage signal and output the voltage signal to the detection circuit (4); The selection unit (3) is arranged on the outer surface of the pen-shaped housing (1) and is connected to the detection circuit (4), and is used to output a reference signal corresponding to the corresponding function to the detection circuit (4) based on the function of the test pen selected by the user; The detection circuit (4) is used to compare the voltage signal with a reference signal, output the detection result and send it to the display unit (5) for display.

2. The electric test pencil according to claim 1, characterized in that: The selection unit (3) comprises a key circuit (31) and a multiplexer (32); The multiplexer (32) is connected to the key circuit (31) and the detection circuit (4) respectively, determines the function of the electric tester based on the output of the key circuit (31) and outputs a reference signal corresponding to the corresponding function.

3. The electric test pencil according to claim 2, characterized in that: The detection circuit (4) comprises a plurality of subtraction circuits (41); Each subtraction circuit (41) is respectively connected to the demultiplexer (32) and is used for subtracting the reference signal output by the demultiplexer (32) from the voltage signal to obtain a detection result, and sending the detection result to the display unit (5) for display.

4. The electric test pencil according to claim 3, characterized in that: The electric tester also includes: an amplifier circuit (6), a filter circuit (7) and a power supply unit (8); The amplifying circuit (6) is respectively connected to the sensing unit (2) and the filtering circuit (7), and is used to obtain the voltage signal of the sensing unit (2), and amplify the voltage signal and send it to the filtering circuit (7); The filter circuit (7) is connected to a plurality of subtraction circuits (41) respectively, and is used for filtering the voltage signal and sending the signal to each subtraction circuit (41) respectively; The power supply unit (8) is embedded in the pen-shaped housing (1) and is respectively connected to the detection circuit (4) and the display unit (5) for providing electrical energy.

5. The electric test pencil according to claim 1, characterized in that: The display unit (5) comprises: a buzzer (51) and / or an indicator light (52).

6. The electric test pencil according to claim 1, characterized in that: The sensing unit (2) comprises a sensing probe (21) and a sensing antenna (22).

7. The electric test pencil according to claim 4, characterized in that: The power supply unit (8) is a rechargeable lithium battery.

8. The electric test pencil according to claim 5, characterized in that: The indicator light (52) is an LED light.

9. The electric test pencil according to claim 6, characterized in that: The induction probe (21) is made of polymer nano-magnetic sensitive material.

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