Measuring device

Abstract

The present application relates to a measuring device, including a first switch selection module, a voltage measurement module, a second switch selection module, a current measurement module, a control module and a current detection module. The first switch selection module is used to receive an electrical signal to be measured; the input end of the current measurement module is connected to the output end of the second switch selection module; the control module is used to control the on-off state of the first switch selection module and the second switch selection module according to a preset rule to change the working state of the voltage measurement module and the working state of the current measurement module; the current detection module is used to control the second switch selection module to turn off when the signal output by the voltage measurement module is greater than the first preset electrical signal. The measuring device realizes automatic switching of the measurement mode based on the control module and combines the hardware circuit to realize rapid disconnection of the measurement circuit when overvoltage / overcurrent occurs to avoid burning the device.

Description

Technical Field

[0001] The present application relates to the field of measurement technology, and in particular to a measuring device. Background Art

[0002] With the development of the electrical field, there are more and more types of performance parameters that characterize electronic instruments. Operators are easily confused when measuring different types of performance parameters, which leads to safety problems caused by misoperation during the measurement process. For example, when using an oscilloscope, the operator may forget or make an operation error, which may cause the oscilloscope to be in the wrong gear or the probe to be inserted in the wrong position, thus causing the oscilloscope to burn out, or even cause serious personal injury or production accidents.

[0003] In order to solve the above problems, traditional technologies add devices such as vibration and voice to the measuring instrument to remind users to use the wrong gear or connect the test leads incorrectly. However, there is still a risk of instrument damage due to wrong gear connection. Summary of the invention

[0004] Based on this, it is necessary to provide a measuring device to address the above technical issues.

[0005] In a first aspect, a measuring device is provided, comprising:

[0006] A first switch selection module, wherein an input end of the first switch selection module is used to connect to an electrical signal output end of the device under test, and is used to receive an electrical signal under test, where the electrical signal under test is an electrical signal output by the device under test;

[0007] A voltage measuring module, wherein an input end of the voltage measuring module is connected to an output end of the first switch selection module;

[0008] A second switch selection module, wherein the input end of the second switch selection module is used to connect to the electrical signal output end of the device under test;

[0009] A current measuring module, an input end of the current measuring module is connected to an output end of the second switch selecting module;

[0010] A control module, wherein an input end of the control module is used to connect to an electrical signal output end of the device under test, a first output end of the control module is connected to a control end of a first switch selection module, and a second output end of the control module is connected to a first control end of a second switch selection module, and the control module is used to control the on-off state of the first switch selection module and the second switch selection module according to a preset rule to change the working state of the voltage measurement module and the working state of the current measurement module;

[0011] A current detection module, wherein the input end of the current detection module is connected to the output end of the voltage measurement module, the output end of the current detection module is connected to the second control end of the second switch selection module, and the current detection module is used to control the second switch selection module to shut down when the signal output by the voltage measurement module is greater than the first preset electrical signal.

[0012] In one embodiment, the current detection module includes:

[0013] A first comparator, wherein a first input terminal of the first comparator is connected to an output terminal of the voltage measurement module, a second input terminal of the first comparator is used to receive a first preset electrical signal, and the first comparator outputs a first electrical signal when a signal output by the voltage measurement module is greater than the first preset electrical signal;

[0014] A first trigger, wherein the input end of the first trigger is connected to the output end of the first comparator, the output end of the first trigger is connected to the second control end of the second switch selection module, and the first trigger is used to output a second electrical signal when receiving a first electrical signal, and the second electrical signal is used to trigger the second switch selection module to shut down.

[0015] In one embodiment, the current detection module further includes:

[0016] A second comparator, wherein a first input terminal of the second comparator is connected to an output terminal of the voltage measurement module, a second input terminal of the second comparator is used to access a second preset electrical signal, a third input terminal of the second comparator is used to access a third preset electrical signal, and the second comparator outputs a third electrical signal or a fourth electrical signal;

[0017] Among them, the second preset electrical signal is smaller than the first preset electrical signal, and the third preset electrical signal is smaller than the second preset electrical signal, the third electrical signal is generated by the second comparator when the signal output by the voltage measurement module is larger than the second preset electrical signal and smaller than the first preset electrical signal, and the fourth electrical signal is generated by the second comparator when the signal output by the voltage measurement module is larger than the third preset electrical signal and smaller than or equal to the second preset electrical signal;

[0018] A second trigger, an input end of the second trigger is connected to the output end of the second comparator, an output end of the second trigger is connected to the second control end of the second switch selection module, the second trigger is used to control the second switch selection module to be in a first conduction state when a third electrical signal is received, and is used to control the second switch selection module to be in a second conduction state when a fourth electrical signal is received.

[0019] In one embodiment, the measuring device further comprises:

[0020] The frequency measurement module has an input end connected to the output end of the voltage measurement module and the output end of the current measurement module respectively.

[0021] In one embodiment, the measuring device further comprises:

[0022] The effective value measurement module has an input end connected to the output end of the voltage measurement module and the output end of the current measurement module respectively.

[0023] In one embodiment, the measuring device further comprises:

[0024] a resistance measuring module, wherein an input end of the resistance measuring module is connected to an output end of the second switch selecting module;

[0025] The second comparator is used to output a fifth electrical signal, where the fifth electrical signal is generated by the second comparator when the signal output by the voltage measurement module is less than or equal to the third preset electrical signal;

[0026] The second trigger is used to control the second switch selection module to be in the third conduction state when receiving the fifth electrical signal, so that the resistance measurement module works.

[0027] In one embodiment, the measuring device further comprises:

[0028] A power supply module, the output end of the power supply module is connected to the power supply end of the resistance measurement module, and the power supply module is used to supply power to the resistance measurement module.

[0029] In one embodiment, the first switch selection module includes:

[0030] A first range position switch, wherein the input end of the first range position switch is used to be connected to the output end of the electrical signal to be measured of the external device to be measured, the output end of the first range position switch is connected to the output end of the voltage measurement module, and the first range position switch is in an on state when the electrical signal to be measured is within a first range;

[0031] A second range position switch, wherein the input end of the second range position switch is used to be connected to the output end of the electrical signal to be measured of the external device to be measured, the output end of the second range position switch is connected to the output end of the voltage measurement module, and the second range position switch is in an on state when the electrical signal to be measured is in the second range;

[0032] A third range position switch, wherein the input end of the third range position switch is used to be connected to the output end of the electrical signal to be measured of the external device to be measured, the output end of the third range position switch is connected to the output end of the voltage measurement module, and the third range position switch is in an on state when the electrical signal to be measured is in a third range;

[0033] The lower limit value in the third range is greater than or equal to the upper limit value in the second range, and the lower limit value in the second range is greater than or equal to the upper limit value in the first range.

[0034] In one embodiment, the first range position switch, the second range position switch and the third range position switch are all optocoupler relays.

[0035] In one embodiment, the voltage measurement module includes

[0036] An AC voltage measuring module, wherein the input end of the AC voltage measuring module is connected to the output end of the first switch selection module, the output end of the AC voltage measuring module is connected to the input end of the current detection module, and the AC voltage measuring module is used to measure the AC voltage;

[0037] A DC voltage measuring module, the input end of the DC voltage measuring module is connected to the output end of the first switch selection module, the output end of the DC voltage measuring module is connected to the input end of the current detection module, and the AC voltage measuring module is used to measure the DC voltage.

[0038] The measuring device provided in the embodiment of the present application has at least the following beneficial effects:

[0039] The above-mentioned measuring device includes a first switch selection module, a second switch selection module, a voltage measurement module, a current measurement module and a current detection module. After the device is powered on, the control module controls the on-off state of the first switch selection module and the second switch selection module according to preset rules through the built-in software program to change the working state of the voltage measurement module and the working state of the current measurement module, so as to realize the automatic switching of the measurement mode after the device is powered on. At a certain moment, the second switch selection module is in the on state, and the first switch selection module is also in the on state through the control of the control module. At this time, the electrical signal to be measured enters the voltage measurement module and the current measurement module at the same time, and the current detection module measures and compares the electrical signal to be measured. When it is determined that the electrical signal to be measured is greater than the first preset electrical signal, the current detection module controls the second switch selection module to be disconnected, and performs overcurrent / overvoltage protection. While realizing the automatic switching of the measurement mode, it can avoid the problem of instrument damage caused by excessive access to the electrical signal due to the wrong gear connection, etc., and improve the reliability of the use of the measuring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A schematic diagram of an application environment of a measuring device in an embodiment;

[0042] Figure 2is a schematic structural diagram of a measuring device in one embodiment;

[0043] Figure 3 is a schematic structural diagram of a measuring device in another embodiment;

[0044] Figure 4 is a schematic structural diagram of a measuring device in yet another embodiment;

[0045] Figure 5 is a schematic structural diagram of a first switch selection module of a measuring device in one embodiment;

[0046] Figure 6 A schematic diagram of the structure of a voltage measurement module of a measurement device in one embodiment;

[0047] Figure 7 A schematic diagram of the structure of a frequency measurement module of a measurement device in one embodiment;

[0048] Figure 8 A schematic diagram of the structure of an effective value measurement module of a measurement device in one embodiment;

[0049] Fig. 9 is a structural schematic diagram of a current detection module of a measuring device in one embodiment;

[0050] Fig.10 is a schematic structural diagram of a second switch selection module of a measuring device in one embodiment;

[0051] Fig.11 A schematic diagram of the structure of a current measurement module of a measurement device in one embodiment;

[0052] Fig.12 A schematic diagram of the structure of a resistance measurement module of a measurement device in one embodiment;

[0053] Fig.13 A schematic diagram of the structure of a power supply module of a measuring device in one embodiment;

[0054] Fig.14 FIG. 1 is a schematic diagram of the structure of a resistance range selection switch module of a measuring device in an embodiment. DETAILED DESCRIPTION

[0055] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0057] It can be understood that the terms "first", "second", etc. used in the present application can be used in this article to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0058] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0059] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0060] The measuring device 2 of the present application can be used as follows Figure 1 In the application environment shown, the measuring device 2 is connected to the device under test 4 to measure the electrical signal output by the device under test 4. The measuring device 2 switches the measurement mode cyclically after the power is turned on. After receiving the electrical signal to be measured from the device under test 4, the measuring device 2 selects the measurement mode based on the internal circuit while preventing the internal circuit from burning out due to the access of high voltage or high current. The device under test 4 can be various electronic devices, such as various devices in the power supply network, such as transformers, current transformers, voltage transformers, etc. It can also be a personal computer, a laptop computer, a smart phone, a tablet computer, an Internet of Things device, and a portable wearable device. The Internet of Things device can be a smart speaker, a smart TV, a smart air conditioner, a smart car device, etc. The portable wearable device can be a smart watch, a smart bracelet, a head-mounted device, etc.

[0061] In one embodiment, Figure 2As shown, a measuring device 2 is provided, including a first switch selection module 202 , a voltage measurement module 210 , a second switch selection module 206 , a current measurement module 208 , a control module 204 and a current detection module 212 .

[0062] The input end of the first switch selection module 202 is used to connect to the electrical signal output end of the device under test 4, and is used to receive the electrical signal under test, which is the electrical signal output by the device under test 4; the input end of the voltage measurement module 210 is connected to the output end of the first switch selection module 202; the input end of the second switch selection module 206 is used to connect to the electrical signal output end of the device under test 4; the input end of the current measurement module 208 is connected to the output end of the second switch selection module 206; the input end of the control module 204 is used to connect to the electrical signal output end of the device under test 4, the first output end of the control module 204 is connected to the control end of the first switch selection module 202, and the control module 204 The second output end of the current detection module 212 is connected to the first control end of the second switch selection module 206, and the control module 204 is used to control the on-off state of the first switch selection module 202 and the second switch selection module 206 according to a preset rule to change the working state of the voltage measurement module 210 and the working state of the current measurement module 208; the input end of the current detection module 212 is connected to the output end of the voltage measurement module 210, and the output end of the current detection module 212 is connected to the second control end of the second switch selection module 206. The current detection module 212 is used to control the second switch selection module 206 to turn off when the signal output by the voltage measurement module 210 is greater than the first preset electrical signal.

[0063] The electrical signal to be measured includes voltage and current. The first switch selection module 202 can conduct the electrical signal connection path between the device to be measured 4 and the voltage measurement module 210, or can shut down the path to determine whether the voltage measurement module is working. Considering that the electrical signals to be measured of different devices to be measured 4 are quite different, in order to ensure the accuracy of the signal measurement results of various devices to be measured 4, the first switch selection module 202 may include voltage range selection switches of different ranges, which are used to select different ranges of voltage measurement according to the size of the electrical signal to be measured, and determine whether the voltage measurement module 210 is working. The second switch selection module 206 includes a mode selection switch for switching different measurement modes. Specifically, the mode selection switch includes a current mode selection switch and a resistance mode selection switch. Of course, the second switch selection module 206 can also be an integrated composite switch. Similar to the reason why the first switch selection module 202 can include voltage range selection switches of different ranges, the current mode selection switch can include current range selection switches of different ranges.

[0064] The control module 204 can be a chip such as a single-chip microcomputer, which can control the on and off of each switch module to realize automatic switching control of voltage measurement and current measurement without manual intervention. Specifically, after the measuring device 2 is powered on, the control module 204 controls the first switch selection module 202 and the second switch selection module 206 to switch on and off according to the preset rules based on the built-in program file. For example, the preset rule can be a cyclic on and off, and the speed of the cyclic on and off is a switching at the millisecond level. Specifically, under the control of the control module 204, the on and off switching of the switch selection module is performed once every 2-5 milliseconds. Of course, the preset rule is not limited to the cyclic on and off, and the control module 204 can also determine the key indicators that affect the performance of the device under test 4 according to the type of the device under test 4, and select the above-mentioned switch module according to the key indicators. For example, when the key indicator is the rated voltage, the first switch selection module 202 can be controlled to be turned on first to complete the voltage measurement. When the voltage of the electrical signal to be measured meets the rated voltage, the second switch selection module 206 is controlled to measure other indicators such as current. When the voltage of the electrical signal to be tested does not meet the rated voltage, it means that the device to be tested 4 is unqualified, and no other measurement is required. Based on the measurement requirements of the application scenario, the preset rules can be configured, which are not exhaustive here.

[0065] The measuring device 2 provided in the embodiment of the present application, through the above circuit structure, when the type and value of the electrical signal to be measured are unknown and the measuring mode of the measuring device 2 is constantly switched, at a certain moment, the electrical signal to be measured can be simultaneously input from the first switch selection module 202 to the voltage measurement module 210, and input from the second switch selection module 206 to the current measurement module 208, the electrical signal to be measured is converted into a current signal by the voltage measurement module 210 and then input to the current detection module 212, and the current detection module 212 detects whether the above current signal is greater than the first preset signal (the size of the first preset signal can indicate whether the size of the electrical signal to be measured is overvoltage / overcurrent) , and when the current signal is greater than the first preset signal, the current detection module 212 outputs a control electrical signal to control the second switch selection module 206 to turn off. For example, the switch module can be disconnected by controlling electronic components such as relays and switch tubes in the second switch selection module 206, and the control priority and control speed of the second switch selection module 206 are higher than the on-off control priority and control speed of the first switch selection module 202 and the second switch selection module 206 based on preset rules in the control module 204, that is, when overcurrent / overvoltage occurs, the second switch selection module 206 is turned off before the electrical signal to be measured enters the current measurement module 208.

[0066] The above-mentioned measuring device 2 realizes the continuous switching of the measuring mode after the device is powered on through the control module 204, realizes the automatic switching of the measuring mode of the measuring device 2, that is, realizes the blind selection function of the measuring mode of the measuring device 2, and at the same time, on this basis, sets the current detection mode to realize the rapid shutdown of the electronic components in the second switch selection module 206 when overcurrent / overvoltage occurs, thereby avoiding the measuring device 2 from being damaged when the measuring device 2 is accidentally connected to a high-amplitude electrical signal, and improving the reliability and service life of the measuring device 2. Improve the fault tolerance of the operation of the measuring device 2 and reduce the requirements for operators.

[0067] In one embodiment, the control module 204 controls the first switch selection module 202 and the second switch selection module 206 according to preset rules to implement the following scheme: after the measuring device 2 is powered on, the electrical signal to be measured of the device to be measured 4 is simultaneously input to the input end of the first switch selection module 202, the input end of the second switch selection module 206 and the control module 204 in the measuring device 2, and the control module 204 detects the electrical signal to be measured; when it is detected that the electrical signal to be measured is a voltage signal and the voltage is greater than the first voltage threshold, the first switch selection module 202 is controlled to remain in the on state, and the second switch selection module 206 is disconnected, so as to keep the voltage measurement module 210 in the working state, and then the electrical signal to be measured is measured and the measurement result is output to the display interface of the measuring device 2, wherein the first voltage threshold can be 3V.

[0068] In one embodiment, the control module 204 can also determine whether the electrical signal to be measured is a voltage signal, and when the electrical signal to be measured is a voltage, control the first switch selection module 202 to select the voltage range. The first preset electrical signal can be a voltage signal or a current signal, and the selection of its signal form depends on the specific circuit of the current detection module 212. The voltage measurement module 210 measures voltage based on the resistor voltage division method, that is, by connecting resistors with different resistance values ​​to divide the voltage, and converting the voltage signal into a current signal in the voltage measurement module 210, and calculating the voltage based on Ohm's law U=I*R. The current detection module 212 can be an overcurrent protection circuit, which is used to detect whether the current signal output by the above-mentioned voltage measurement module 210 is greater than the first preset electrical signal. Among them, the first preset electrical signal refers to a current signal output after passing through the voltage measurement module 210 when an electrical signal to be measured (which can be the maximum value allowed to be connected) is allowed to be connected to ensure that the measuring device 2 does not fail. When the above-mentioned current signal is greater than the first preset signal, the second switch selection module 206 is controlled to be turned off.

[0069] In one embodiment, if Figure 2As shown, the current detection module 212 includes a first comparator 2122 and a first trigger 2124. The first input end of the first comparator 2122 is connected to the output end of the voltage measurement module 210, and the second input end of the first comparator 2122 is used to access the first preset electrical signal. When the signal output by the voltage measurement module 210 is greater than the first preset electrical signal, the first comparator 2122 outputs the first electrical signal. The input end of the first trigger 2124 is connected to the output end of the first comparator 2122, and the output end of the first trigger 2124 is connected to the second control end of the second switch selection module 206. The first trigger 2124 is used to output the second electrical signal when receiving the first electrical signal, and the second electrical signal is used to trigger the second switch selection module 206 to shut down.

[0070] Among them, the first comparator 2122 can be a current comparator or a voltage comparator, and can compare the size between the input signal and one or more preset electrical signals. The first trigger 2124 can be one of a level trigger, an edge trigger, and a pulse trigger, and can change the output state of the trigger according to the input signal, thereby outputting different electrical signals. For example, the first comparator 2122 can compare the current signal output by the voltage measurement module 210 with the first preset electrical signal (preset current, for example, a preset current of 500mA); the first trigger 2124 can output a second electrical signal after the first electrical signal output after the first comparator 2122 is connected and compared with the signal; when the current signal output by the voltage measurement module 210 is greater than the first preset electrical signal, the first electrical signal is output; the first trigger 2124 outputs a second electrical signal according to the first electrical signal received from the first comparator 2122. For example, under the specific selection of a first comparator 2122, the first electrical signal is a high-level signal, and at this time, the first trigger 2124 outputs a second electrical signal to control the second switch selection module 206 to turn off.

[0071] Specifically, the electrical signal to be tested output by the device to be tested 4 is input to the voltage measurement module 210 through the first switch selection module 202. The voltage measurement module 210 converts the input electrical signal to be tested into a current signal. The first comparator 2122 receives the current signal output by the voltage measurement module 210, compares the current signal with the first preset electrical signal, and outputs the first electrical signal when the current signal is greater than the first preset electrical signal. The first trigger 2124 receives the first electrical signal and outputs the second electrical signal. The second switch selection module 206 is controlled to be in an off state under the control of the second electrical signal.

[0072] The above-mentioned current detection module 212 is configured with the first comparator 2122 and the first trigger 2124, and there is no need to introduce a control chip for over-current and over-voltage protection. When a large-value electrical signal is connected, the second switch selection module 206 can be promptly controlled to be turned off, thereby avoiding burning of the measuring device 2 and realizing over-current and over-voltage protection at a low cost.

[0073] In one embodiment, if Figure 2 As shown, the current detection module 212 also includes a second comparator 2126 and a second trigger 2128. The first input terminal of the second comparator 2126 is connected to the output terminal of the voltage measurement module 210, the second input terminal of the second comparator 2126 is used to access the second preset electrical signal, the third input terminal of the second comparator 2126 is used to access the third preset electrical signal, and the second comparator 2126 outputs the third electrical signal or the fourth electrical signal;

[0074] The second preset electrical signal is smaller than the first preset electrical signal, and the third preset electrical signal is smaller than the second preset electrical signal. The third electrical signal is generated by the second comparator 2126 when the signal output by the voltage measurement module 210 is larger than the second preset electrical signal and smaller than the first preset electrical signal. The fourth electrical signal is generated by the second comparator 2126 when the signal output by the voltage measurement module 210 is larger than the third preset electrical signal and smaller than or equal to the second preset electrical signal.

[0075] The input end of the second trigger 2128 is connected to the output end of the second comparator 2126, and the output end of the second trigger 2128 is connected to the second control end of the second switch selection module 206. The second trigger 2128 is used to control the second switch selection module 206 to be in the first conduction state when the third electrical signal is received, and is used to control the second switch selection module 206 to be in the second conduction state when the fourth electrical signal is received.

[0076] Among them, similarly, the second comparison module 2126 can be a current comparator or a voltage comparator, and can compare the size between the input signal and one or more preset electrical signals. The first trigger 2124 can be one of a level trigger, an edge trigger, and a pulse trigger, and can change the output signal of the trigger according to the input signal to control the second switch selection module 206 to be in different conduction states. For example, the second comparator 2126 can compare the current signal output by the voltage measurement module 210 with the second preset electrical signal (preset current, for example, a preset current of 50mA) or the third preset electrical signal (preset current, for example, a preset current of 2mA); the second trigger 2128 can control the second switch selection module 206 to be in different conduction states according to different electrical signals output by the second comparator 2126, so as to realize the current range selection when the size of the electrical signal to be measured is different.

[0077] For example, when the current signal output by the voltage measurement module 210 is greater than the second preset electrical signal, a third electrical signal is output; the second trigger 2128 controls the second switch selection module 206 to be in a first conduction state according to the third electrical signal received from the second comparator 2126, wherein the first conduction state is to enable the current measurement module 208 to measure current within a preset range, such as a current range of 50mA-500mA.

[0078] When the current signal output by the voltage measurement module 210 is greater than the third preset electrical signal, a fourth electrical signal is output; the second trigger 2128 controls the second switch selection module 206 to be in a second conduction state according to the fourth electrical signal received from the second comparator 2126, wherein the second conduction state is to enable the current measurement module 208 to measure current in another range, such as a current range of 2mA-50mA.

[0079] Specifically, the electrical signal to be tested output by the device to be tested 4 is input to the voltage measurement module 210 through the first switch selection module 202. The voltage measurement module 210 converts the input electrical signal to be tested into a current signal. The second comparator 2126 receives the current signal output by the voltage measurement module 210, and compares the current signal with the second preset electrical signal or the third preset electrical signal. When the current signal is greater than the second preset electrical signal, the third electrical signal is output. The second trigger 2128 receives the third electrical signal and controls the second switch selection module 206 to be in the first conduction state accordingly. When the current signal is greater than the third preset electrical signal, the fourth electrical signal is output. The second trigger 2128 receives the fourth electrical signal and controls the second switch selection module 206 to be in the second conduction state accordingly.

[0080] The measuring device 2 detects the electrical signal to be measured by setting the second comparator 2126 and the second trigger 2128, and controls the second switch selection module 206 to select different measurement ranges based on the detection results, thereby achieving multi-range high-precision measurement.

[0081] In one embodiment, if Figure 2 As shown, the measuring device 2 further includes a frequency measuring module 218 , and an input end of the frequency measuring module 218 is respectively connected to an output end of the voltage measuring module 210 and an output end of the current measuring module 208 .

[0082] The frequency measurement module 218 is used to measure the frequency of the voltage output by the voltage measurement module 210 and the current output by the current measurement module 208 .

[0083] Specifically, the electrical signal to be tested output by the device to be tested 4 is measured by the voltage measurement module 210 and the current measurement module 208, and then output to the frequency measurement module 218 for frequency measurement and output to the display interface. For example, for conventional voltage or current, the waveform is generally a sine wave. When the external sine wave is passed through Figure 6 The waveform conversion hardware circuit shown is converted into a square wave waveform, and the square wave waveform is connected to the frequency measurement module 218 through the frequency measurement port. The frequency measurement module 218 calculates the frequency value of the square wave waveform based on the period measurement method (i.e., measuring how many periods of the standard signal are contained in one signal period of the measured signal, and then calculating the frequency of the measured signal based on the number of standard signal periods and the period of the standard signal.).

[0084] The measuring device 2 mentioned above realizes the frequency measurement of the electrical signal to be measured by providing the frequency measurement module 218 , thereby realizing the multifunctionality of the measuring device 2 .

[0085] In one embodiment, if Figure 2 As shown, the measuring device 2 further includes an effective value measuring module 220 , and an input end of the effective value measuring module 220 is respectively connected to an output end of the voltage measuring module 210 and an output end of the current measuring module 208 .

[0086] The effective value measurement module 220 is used to perform effective value measurement on the voltage output by the voltage measurement module 210 and the current output by the current measurement module 208 .

[0087] Specifically, the electrical signal to be tested output by the device to be tested 4 is measured by the voltage measurement module 210 and the current measurement module 208 , and then output to the effective value measurement module 220 for effective value measurement and output to the display interface.

[0088] The above-mentioned measuring device 2 realizes effective value measurement of the electrical signal to be measured by providing an effective value measurement module 220 , thereby further realizing the multifunctionality of the measuring device 2 .

[0089] In one embodiment, if Figure 2 As shown, the measuring device 2 also includes a resistance measuring module 214, the input end of the resistance measuring module 214 is connected to the output end of the second switch selection module 206; the second comparator 2126 is used to output a fifth electrical signal, and the fifth electrical signal is generated by the second comparator 2126 when the signal output by the voltage measuring module 210 is less than or equal to the third preset electrical signal; the second trigger 2128 is used to control the second switch selection module 206 to be in the third conduction state when receiving the fifth electrical signal, so that the resistance measuring module 214 works.

[0090] Among them, the fifth electrical signal is generated when the connected electrical signal to be measured is less than the third preset electrical signal, and the third conduction state is to put the resistance measurement module 214 into a working state. In one embodiment, the second switch selection module includes a resistance mode selection switch, wherein the resistance mode selection switch also includes a plurality of resistance range selection switches with different ranges, wherein the selection of different resistance measurement ranges is automatically switched according to the resistance value.

[0091] Specifically, the electrical signal to be tested output by the device to be tested 4 is input to the voltage measurement module 210 through the first switch selection module 202. The voltage measurement module 210 converts the input electrical signal to be tested into a current signal. The second comparator 2126 receives the current signal output by the voltage measurement module 210, and compares the above current signal with the third preset electrical signal. When the current signal is less than or equal to the above third preset electrical signal, a fifth electrical signal is output. The second trigger 2128 receives the above fifth electrical signal and controls the second switch selection module 206 to be in the third conduction state accordingly.

[0092] The measuring device 2 mentioned above realizes the resistance measurement function by providing the resistance measurement module 214 , thereby further realizing the multi-functionality of the measuring device 2 .

[0093] In one embodiment, if Figure 2 As shown, the measuring device 2 also includes a power module 216, the output end of the power module 216 is connected to the power supply end of the resistance measuring module 214, and the power module 216 is used to supply power to the resistance measuring module 214. The power module 216 can be a battery. The input end of the power module 216 can also be used to connect an external power supply, for example, to connect an external 5V DC power supply.

[0094] In a specific embodiment, the power module 216 may be a constant voltage power circuit, wherein the constant voltage power circuit includes at least one amplifier, and the amplifier is used to amplify the input electrical signal to supply power to the resistance measurement module 214 .

[0095] Specifically, when the resistance measurement module 214 is in operation, the power supply module 216 outputs a weak constant current source current signal to the resistance measurement module 214 through the output terminal as a measurement signal source for the external resistance, and detects the power-on voltage drop of the test lead through the built-in voltage channel to calculate the resistance value of the measured resistance.

[0096] In one embodiment, if Figure 3 As shown, the first switch selection module 202 includes a first range position switch 2022 , a second range position switch 2024 and a third range position switch 2026 .

[0097] The input end of the first range position switch 2022 is used to be connected to the output end of the electrical signal to be measured of the external device to be measured 4, and the output end of the first range position switch 2022 is connected to the output end of the voltage measurement module 210. The first range position switch 2022 is in an on state when the electrical signal to be measured is within the first range;

[0098] The input end of the second range position switch 2024 is used to be connected to the output end of the electrical signal to be measured of the external device to be measured 4, and the output end of the second range position switch 2024 is connected to the output end of the voltage measurement module 210. The second range position switch is in an on state when the electrical signal to be measured is in the second range;

[0099] The input end of the third range position switch 2026 is used to connect to the output end of the electrical signal to be measured of the external device 4 to be measured, and the output end of the third range position switch 2026 is connected to the output end of the voltage measurement module 210. The third range position switch is in the on state when the electrical signal to be measured is in the third range.

[0100] Among them, the first range is the minimum measurement range of the electrical signal to be measured that can be measured when the voltage measurement module 210 is in operation. Specifically, in a specific embodiment, the first measurement range can be 0-2V; similarly, the second range is the second measurement range of the electrical signal to be measured that can be measured when the voltage measurement module 210 is in operation. Among them, for example, in a specific embodiment, the second range can be 0-20V; the third range is the third measurement range of the electrical signal to be measured that can be measured when the voltage measurement module 210 is in operation. Specifically, in a specific embodiment, the third range can be 0-500V.

[0101] Specifically, when the electrical signal to be measured is a voltage signal, the voltage measurement module 210 is in an on state, wherein the control module 204 determines the above voltage signal and controls the on and off of the first range gear switch 2022, the second range gear switch 2024 and the third range gear switch 2026 according to the specific amplitude of the voltage signal.

[0102] The measuring device 2 performs range setting in the first switch selection module 202 , and achieves a larger measuring range and more accurate measurement by setting the range position switch of different measuring ranges.

[0103] In one embodiment, the first range position switch 2022, the second range position switch 2024 and the third range position switch 2026 are optocoupler relays. The optocoupler relays can be integrated with multiple optocouplers and MOS (field effect transistors) to achieve signal isolation, avoid signal interference, and achieve fast switching of different ranges of the measuring device 2.

[0104] In one embodiment, if Figure 4The voltage measuring module 210 shown includes an AC voltage measuring module 2104 and a DC voltage measuring module 2102; the input end of the AC voltage measuring module 2104 is connected to the output end of the first switch selection module 202, the output end of the AC voltage measuring module 2104 is connected to the input end of the current detection module 212, and the AC voltage measuring module 2104 is used to measure the AC voltage; the input end of the DC voltage measuring module 21020 is connected to the output end of the first switch selection module 202, the output end of the DC voltage measuring module 2102 is connected to the input end of the current detection module 212, and the AC voltage measuring module 2104 is used to measure the DC voltage.

[0105] Among them, the DC voltage measurement module 2102 can be a DC voltmeter, and the AC voltage measurement module 2104 can be an integration of an AC / DC (alternating current / direct current) conversion circuit and a DC voltmeter. The input end of the AC / DC (alternating current / direct current) conversion circuit is connected to the device under test 4 through the above-mentioned second switch selection module 206, and is used to measure the AC power of the device under test 4 when the second switch selection module 206 is turned on, and convert it into a DC signal and transmit it to the DC voltmeter for display.

[0106] In order to further explain the present application, a specific example is provided below, in which the measuring device is an oscilloscope. The specific circuit connection and implementation method of the oscilloscope are shown in FIG. Figure 5-14 As shown, those skilled in the art can know the specific implementation method from the figure, which will not be described in detail here. Figure 5 As shown, Figure 5 It is a first switch selection module 202, wherein the first switch selection module 202 includes a first range gear switch 2022, a second range gear switch 2024 and a third range gear switch 2026, which are respectively used to control the on and off of different range gears.

[0107] The test leads POLE1 and POLE2 are signal input terminals. The possible objects that the user may measure are: hanging, resistance, voltage, and current. The signals enter the meter through the INPUT input channel. The control module 204 is in a high-speed patrol state for a long time under the control of the software, and can cycle back and forth in the order of "voltage-current-resistance".

[0108] The meter first turns on the voltage detection channel and measures the voltage strength of the input signal in real time. If the input voltage value reaches its minimum limit of 3V, it enters the voltage measurement process, that is, the signal is transmitted to Figure 6 The voltage measurement module 210 shown. The voltage measurement module 210 includes a DC voltage measurement module 2102 and an AC voltage measurement module 2104; in a specific selection, as Figure 6As shown, the DC voltage measurement module 2102 includes an amplifier U4A and electronic components adapted based on the amplifier, and the AC voltage measurement module 2104 includes an amplifier U4B and electronic components adapted based on the amplifier. After the voltage measurement module 210 performs measurement, the signal is simultaneously transmitted to Figure 7 The frequency measurement module 218 shown and Figure 8 The effective value measurement module 220 shown, the LCD screen displays the signal voltage value, waveform, and frequency information in real time. If the user continues to maintain this state (the connection between the test lead and the signal is not interrupted), the oscilloscope will continue to stay in the current state, and the meter will still respond to the key (the measuring device can be provided with a power switch key, a HOLD key, a time domain adjustment key, and other function keys, and each function key is connected to the control module 204). If the connection between the test lead and the signal is interrupted (such as the signal disappears, the user lifts the test lead to cause the signal to be interrupted, etc.), the oscilloscope ends this measurement process and enters the signal patrol state again.

[0109] If the control module 204 does not find a voltage signal from the device under test, it is confirmed that the current test lead is not connected to a voltage signal, and the control module 204 switches to the current detection mode by controlling the second switch selection module 206. Fig. 9 The current detection module 210 shown controls the Fig.10 The second switch selection module 206 shown in FIG. 1 turns on the current mode selection switch, thereby turning on the current mode selection switch. Fig.11 The current measurement module 208 shown in FIG. Figure 7 The frequency measurement module 218 shown and Figure 8 In the effective value measurement module 220 shown, the LCD screen continuously displays key information such as the measured current value, current waveform, waveform frequency, etc. At this time, the meter automatically responds to various key information such as voltage measurement, and only terminates the current measurement and enters a new round of patrol process when the current signal disappears.

[0110] If the control module 204 does not detect the voltage and current signals, it is considered that there is no input signal in this measurement and the resistance measurement process is automatically entered, that is, by Fig. 9 The current detection module shown in the figure outputs a resistance mode switching signal to control the Fig.10 The integrated module U13 of the second switch selection module 206 is connected as shown in FIG. Fig.12 The resistance measurement module 214 shown in FIG. 2 is a flow chart showing the resistance measurement module 214 shown in FIG. Fig.13 The power module 216 shown in the figure outputs a weak constant current source current signal as a measurement signal source of the external resistance, and calculates the resistance value of the measured resistance through the built-in voltage channel to detect the voltage drop of the meter pen, and controls the measured resistance value according to the measured resistance value. Fig.14The resistance range selection switch module shown is used to switch the resistance measurement range, so as to display the resistance measurement results with higher accuracy. If the user does not connect the resistance to be measured at this time, its current signal cannot form a loop, and the test lead cannot generate a voltage signal. The meter automatically jumps to the voltage measurement process and repeats. Otherwise, the oscilloscope displays the currently measured resistance value and keeps it until the measurement is ended (the test lead current loop is disconnected).

[0111] The above-mentioned oscilloscope is based on the above-mentioned circuit design, and realizes the measurement of voltage, current, and resistance and automatic gear switching under the control of the software program built into the control chip such as the single-chip microcomputer. Due to the randomness of the user's measurement signal, there is a possibility that the user suddenly connects the meter to a large voltage signal for measurement. When such an accident occurs, the current detection module 212 inside the oscilloscope is quickly switched in a hardware manner such as a trigger. Specifically, when the current working mode of the oscilloscope is in the current gear, that is, when the current measurement module 208 is in the on state, at this time, since a large voltage signal is connected, the control chip simultaneously connects the voltage measurement module 210 for measurement. This voltage measurement module 210 measures and converts the voltage into current. At this time, if the actual measured oscilloscope current value exceeds 500mA, the current detection module 212 outputs a current overload signal to forcibly cut off the current gear switch corresponding to the current measurement module 208 to avoid overcurrent and accidents. The software forcibly switches the device gear to the voltage measurement mode.

[0112] The above-mentioned oscilloscope can realize the switching of different gears without changing the test lead jack or the meter gear. The software program built into the control chip can realize the measurement of AC voltage, DC voltage, AC current, DC current and resistance. The waveform of the input signal when measuring different gears can be displayed. The instrument can be shut down in time when a large voltage is mistakenly connected to avoid damage to the oscilloscope. It basically meets the measurement requirements of technicians during on-site troubleshooting and realizes rapid location and search of faults.

[0113] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0114] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A measuring device, characterized in that: include: A first switch selection module, wherein an input end of the first switch selection module is used to connect to an electrical signal output end of a device under test, and is used to receive an electrical signal under test, wherein the electrical signal under test is an electrical signal output by the device under test; a voltage measuring module, wherein an input end of the voltage measuring module is connected to an output end of the first switch selecting module; A second switch selection module, wherein the input end of the second switch selection module is used to connect to the electrical signal output end of the device under test; a current measuring module, wherein an input end of the current measuring module is connected to an output end of the second switch selecting module; A control module, wherein an input end of the control module is used to connect to an electrical signal output end of a device under test, a first output end of the control module is connected to a control end of the first switch selection module, and a second output end of the control module is connected to a first control end of the second switch selection module, and the control module is used to control the on-off state of the first switch selection module and the second switch selection module according to a preset rule to change the working state of the voltage measurement module and the working state of the current measurement module; A current detection module, wherein the input end of the current detection module is connected to the output end of the voltage measurement module, and the output end of the current detection module is connected to the second control end of the second switch selection module, and the current detection module is used to control the second switch selection module to shut down when the signal output by the voltage measurement module is greater than the first preset electrical signal.

2. The measuring device according to claim 1, characterized in that The current detection module comprises: A first comparator, wherein a first input terminal of the first comparator is connected to an output terminal of the voltage measurement module, a second input terminal of the first comparator is used to receive the first preset electrical signal, and the first comparator outputs a first electrical signal when the signal output by the voltage measurement module is greater than the first preset electrical signal; A first trigger, wherein the input end of the first trigger is connected to the output end of the first comparator, the output end of the first trigger is connected to the second control end of the second switch selection module, the first trigger is used to output a second electrical signal when receiving the first electrical signal, and the second electrical signal is used to trigger the second switch selection module to shut down.

3. The measuring device according to claim 2, characterized in that The current detection module also includes: A second comparator, wherein a first input terminal of the second comparator is connected to an output terminal of the voltage measurement module, a second input terminal of the second comparator is used to access a second preset electrical signal, a third input terminal of the second comparator is used to access a third preset electrical signal, and the second comparator outputs a third electrical signal or a fourth electrical signal; Wherein, the second preset electrical signal is smaller than the first preset electrical signal, and the third preset electrical signal is smaller than the second preset electrical signal, the third electrical signal is generated by the second comparator when the signal output by the voltage measurement module is larger than the second preset electrical signal and smaller than the first preset electrical signal, and the fourth electrical signal is generated by the second comparator when the signal output by the voltage measurement module is larger than the third preset electrical signal and smaller than or equal to the second preset electrical signal; a second trigger, wherein the input end of the second trigger is connected to the output end of the second comparator, the output end of the second trigger is connected to the second control end of the second switch selection module, and the second trigger is used to control the second switch selection module to be in a first conduction state when the third electrical signal is received, and is used to control the second switch selection module to be in a second conduction state when the fourth electrical signal is received.

4. The measuring device according to claim 1, characterized in that The measuring device also includes: A frequency measurement module, wherein the input end of the frequency measurement module is respectively connected to the output end of the voltage measurement module and the output end of the current measurement module.

5. The measuring device according to claim 1, characterized in that The measuring device also includes: An effective value measurement module, wherein the input end of the effective value measurement module is respectively connected to the output end of the voltage measurement module and the output end of the current measurement module.

6. The measuring device according to claim 3, characterized in that The measuring device also includes: a resistance measuring module, wherein an input end of the resistance measuring module is connected to an output end of the second switch selecting module; The second comparator is used to output a fifth electrical signal, where the fifth electrical signal is generated by the second comparator when the signal output by the voltage measurement module is less than or equal to the third preset electrical signal; The second trigger is used to control the second switch selection module to be in a third conduction state when receiving the fifth electrical signal, so as to enable the resistance measurement module to operate.

7. The measuring device according to claim 6, characterized in that The measuring device also includes: A power supply module, wherein the output end of the power supply module is connected to the power supply end of the resistance measurement module, and the power supply module is used to supply power to the resistance measurement module.

8. The measuring device according to claim 1, characterized in that The first switch selection module comprises: A first range position switch, wherein the input end of the first range position switch is used to be connected to the output end of the electrical signal to be measured of the external device to be measured, the output end of the first range position switch is connected to the output end of the voltage measurement module, and the first range position switch is in an on state when the electrical signal to be measured is within a first range; A second range position switch, wherein the input end of the second range position switch is used to be connected to the output end of the electrical signal to be measured of the external device to be measured, the output end of the second range position switch is connected to the output end of the voltage measurement module, and the second range position switch is in an on state when the electrical signal to be measured is in the second range; A third range position switch, wherein the input end of the third range position switch is used to be connected to the output end of the electrical signal to be measured of the external device to be measured, the output end of the third range position switch is connected to the output end of the voltage measurement module, and the third range position switch is in an on state when the electrical signal to be measured is in a third range; The lower limit value in the third range is greater than or equal to the upper limit value in the second range, and the lower limit value in the second range is greater than or equal to the upper limit value in the first range.

9. The measuring device according to claim 8, characterized in that The first range position switch, the second range position switch and the third range position switch are all optocoupler relays.

10. The measuring device according to claim 1, characterized in that The voltage measurement module includes an AC voltage measuring module, wherein the input end of the AC voltage measuring module is connected to the output end of the first switch selection module, the output end of the AC voltage measuring module is connected to the input end of the current detection module, and the AC voltage measuring module is used to measure the AC voltage; A DC voltage measuring module, wherein the input end of the DC voltage measuring module is connected to the output end of the first switch selection module, the output end of the DC voltage measuring module is connected to the input end of the current detection module, and the AC voltage measuring module is used to measure the DC voltage.

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