Tester with self-testing function

Abstract

The utility model discloses a tester with a self-testing function. The tester includes a self-test function to test a state of a measurement circuit in the tester. For example, a self-test function tests an electrical state, such as an electrical property or a connected or disconnected state, of a component of a measurement circuit. The self-test function also tests a signal state of an electrical component in the measurement circuit, which may include signal detection, signal transmission, or a measurement property of the electrical component. The self-test function improves the user experience of the tester from the aspects of safety and reliability.

Description

Technical Field

[0001] This disclosure generally relates to electrical testing instruments. More particularly, this disclosure relates to a digital multimeter with self-test functionality. Background Technology

[0002] Digital multimeters (“DMMs”) are used to measure various electrical parameters required for services such as servicing, troubleshooting, and maintenance. Such parameters may include AC voltage and current, DC voltage and current, resistance, and continuity. Sometimes, DMMs can measure other parameters, such as capacitance and temperature. DMMs are typically configured as handheld units with knobs for selecting various functions. Multiple lead jacks for accommodating test leads may be provided in the unit's housing (i.e., the casing). The specific jack used may depend on the selected function. A display (e.g., an LCD display) provides readings of the measured parameters.

[0003] Multiple lead jacks or input terminals include a common input terminal and one or more test input terminals. Test input terminals may include volt / ohm input terminals and one or more ampere or microampere input terminals. The common input terminal is coupled to a reference node of the DMM, such as ground, and the leads of the test probe are inserted into one of the test input terminals used for the corresponding measurement task. For example, to measure microamperes, the DMM user must disconnect the test probe from the volt / ohm terminal and connect it to the microampere terminal. Some DMMs may include a single test input terminal. That is, the same test input terminal can be used for both current and voltage measurements in separate measurement modes selected by the user through the DMM's user interface. Furthermore, some DMMs may include test terminals different from test probes and input lead jacks. For example, a DMM may include non-contact test terminals, such as U-shaped recesses, in which a measurement sensor is embedded. The measurement sensor is used to measure the electrical parameters of an object housed in the U-shaped recess without electrical contact with that object.

[0004] The DMM's printed circuit assembly includes several safety components. These safety components are configured to protect the user or the DMM under various measurement conditions, such as when excessive voltage is applied to the measurement terminals. Utility Model Content

[0005] Digital multimeters include a self-test function. This function automatically tests the state of the multimeter's measurement circuitry. For example, it tests the electrical state of components within the measurement circuitry, such as electrical properties or connection / disconnection status. The self-test function also tests the signal state of electrical components in the measurement circuitry, which can include signal detection, signal transmission, or measurement properties of the components. The self-test function improves the user experience of the digital multimeter (DMM) from a safety and reliability perspective.

[0006] Self-test functionality and related circuit configuration are integrated into the DMM circuit and can be selected and activated through the user interface. Before using the DMM for measurement tasks, the user can activate the self-test function to check functionality, such as whether the safety-related components of the DMM circuit are functioning correctly.

[0007] With user selection, the DMM's controller controls the formation of test or inspection paths, such as connecting or disconnecting circuit components, that couple the component under test (DUT) to a test or inspection signal source. Electrical properties (e.g., voltage, current, resistance, etc.) or electrical signals are detected adjacent to the DUT, and the controller analyzes these to determine the DUT's state, such as its electrical or signal state. The results of this analysis are presented to the user through the DMM's user interface.

[0008] These concepts and features, as well as other concepts and features, are illustrated by various embodiments of the example DMM device described herein. Attached Figure Description

[0009] Figure 1 A front view of an example user interface of an example tester according to at least one embodiment of the present disclosure is shown.

[0010] Figure 2-4 Parts of the circuit elements of an example tester according to at least one embodiment of the present disclosure are shown.

[0011] Figure 5 A flowchart illustrating an example method for performing self-testing using an example tester according to at least one embodiment of the present disclosure is shown.

[0012] Figure 6 An example presentation of self-test results according to at least one embodiment of this disclosure is shown. Detailed Implementation

[0013] Test instruments, such as digital multimeters (“DMMs”), may include various safety components on the printed circuit assembly of the DMM. These safety components are configured to protect the user or the DMM under various measurement conditions, such as when excessively high voltage is applied to the input terminals. For example, the DMM may include a high-voltage positive temperature coefficient (“PTC”) thermistor (“PTC”) coupled in series between the input terminals and the voltage measurement component. Under normal operating conditions, the resistance of the PTC may vary between a high-resistance state and a low-resistance state based on the voltage or current applied to it, which helps prevent high current or high voltage from being applied to the vulnerable measurement component of the DMM. For example, when a high voltage is applied, the resistance of the PTC will become high and then withstand the high voltage to protect the measurement circuitry. In typical applications, a resistor such as a 1k ohm resistor may be coupled in series with the PTC. If the PTC or resistor is short-circuited or disconnected, the DMM or the user may be at risk when the DMM is used for high-voltage measurements.

[0014] In another example, a DMM can include a resistor-capacitor (RC) series circuit in the measurement signal path. The RC series circuit can include a discharge resistor and a high-voltage capacitor, which, among other things, are configured as filters to isolate DC voltage when using the DMM to measure AC voltage. If this RC series circuit is short-circuited, open, or bypassed, the DMM will not be able to measure the AC signal correctly.

[0015] For another example, a DMM may include a set of high-rated voltage resistors (“resistor network”) for measuring AC or DC voltage. Each resistor in the resistor network acts as part of a resistive voltage divider, ensuring that a voltage signal with an appropriate dynamic range is fed into the measurement component (e.g., an analog-to-digital (“A / D”) converter). For example, when measuring high voltages, smaller resistors in the resistor network are selected so that the divided voltage signal is within the dynamic range of the A / D converter. The resistor network enables the DMM to measure voltages correctly.

[0016] In addition, a digital signal transceiver (DMM) typically includes an RMS (root mean square) to DC converter, an A / D converter, and a current source for measuring resistance, capacitance, frequency, and other electrical signals. For example, the RMS to DC converter is used to measure AC signals. The current source provides excitation for measuring resistors and capacitors. The A / D converter is used to read the measured signal values ​​through a digital processing unit (e.g., a controller).

[0017] This disclosure recognizes that existing DMM solutions lack internal self-testing capabilities to check for malfunctions in safety-related components or other components. Failure of safety-related electronic components in harsh measurement environments or applications can be extremely dangerous for frontline workers, especially when the DMM is used to measure high voltages or high currents.

[0018] This specification provides an implementation for a DMM with self-test functionality and associated circuitry configuration. The self-test functionality can be implemented through one or more new circuitry and firmware configurations that test one or more target components or components under test on a printed circuit assembly and present the test results to a user, for example, on the DMM's display.

[0019] The self-test function can briefly check safety-related components on the DMM's printed circuit assembly (PCA). This self-test function requires no additional equipment or accessories. These safety components on the DMM are actually useful. They can protect both the end user and the DMM itself, even if the DMM is involved in internal faulty connections.

[0020] exist Figure 1 In the illustrated embodiment, the tester 100 includes a main body or housing frame 102 and a user interface (or I / O interface) 104 located on one or more surfaces of the housing frame 102. The user interface 104 includes a measurement section 110, a mode selection section 130, a keyboard section 140, and a display section or display 150.

[0021] The measuring section 110 includes a measuring interface for connecting measuring equipment (e.g., a probe). As an illustrative example, Figure 1 A measurement section 110 is shown having one or more measurement groups 123 configured for one or more measurement channels. For example, measurement group 123 includes a common (COM) terminal 124, which is configured as a return terminal (or reference point) for all measurement modes of the measurement channels.

[0022] Measurement group 123 includes one or more input terminals 126, 127, and 128. For example, as... Figure 1 As illustrated, measurement group 123 includes an input terminal 126 for voltage measurement mode (AC / DC), an input terminal 127 for milliamp and microamp (AC / DC) level current measurement modes, and an input terminal 128 for other measurement modes, including those for measuring resistance, diode testing, capacitance, and temperature. Furthermore, terminal 128 can be used to connect to other sensor probes to expand the measurement parameters, which can be selected by measurement mode selection mechanism 130 (e.g., controlling relay 132 or controlling rotator 134).

[0023] In some implementations, control relays 132 (e.g., electromechanical relay buttons) are each configured to activate a measurement mode for a measurement channel. Under firmware control, such as input indication via the relay buttons controlling relays 132, the physical signal path of the measurement circuit corresponding to the measurement mode is switched by a set of electromechanical relays. Figure 1 The control relay 132 is illustrated illustratively to include a relay button for measuring AC voltage, DC voltage, AC millivolts, and DC millivolts, but this does not limit the scope of this disclosure. The control relay 132 may include a relay button or a menu under the control of the relay button to select or activate other measurement modes to measure other parameters, such as capacitance, resistance, continuity, or other physical parameters, such as temperature, all of which are included within the scope of this disclosure.

[0024] like Figure 1 As shown, the control relay 132 includes a "test" relay button 136, which is configured to activate one or more self-test functions of the DMM.

[0025] In some implementations, the control rotator 134 is a rotary switch, such as... Figure 1 The diagram illustratively illustrates that it includes positions for selecting measurement modes such as capacitance, diode testing, AC voltage / LoZ (which prevents readings due to ghost voltage), AC / DC amperes and milliamps, AC / DC microamps, temperature, resistance, and continuity, but this does not limit the scope of this disclosure. Furthermore, the control rotator 134 includes positions for various self-test modes (“Test 1”, “Test 2”, “Test 3”, and “Calibration”), which can be selected to activate testing of the corresponding component or function.

[0026] It should be understood that in various implementations, the DMM may include only one of a set of control relays 132 or control rotators 134, and implement a similar ability to select measurement or self-test modes as described herein with respect to the example implementation having both control relays 132 and control rotators 134. Furthermore, control relays 132 and / or control rotators 134, or any of their relay buttons or selection positions, may be used in conjunction with additional options enabled via display section 150. The scope of the specification herein is not limited to any particular configuration of control relays 132 or control rotators 134.

[0027] In some implementations, the user interface 104 includes a main switch 148, which is configured to allow a user to control the selection of a measurement mode or a self-test mode using either the control rotator 134 or the display section 150.

[0028] In some implementations, measurement mode selection or self-test mode selection can be performed remotely via a remote controller that is communication-coupled to the test instrument 100.

[0029] The keyboard section 140 includes various buttons for various functions, including standard digital multimeter buttons such as "hold", "minimum value maximum value", "range", "function", "record" and other buttons for sound signals, relative modes, cursor buttons, information, etc. Figure 1 Some of the standard buttons are illustrated illustratively and do not limit the scope of this disclosure. The keyboard portion 140 also includes one or more menu buttons 142, illustratively shown as four buttons “F1”, “F2”, “F3”, and “F4”, which, among others, are configured to activate functions related to data processing and the presentation of measurement or self-test results. These functions may include calculation functions, plotting or graphing functions, data fusion functions, data interpolation functions, and other functions for processing or presenting measurement or self-test results. Among other things, cursor buttons 144 are also configured to be used in conjunction with the menu buttons 142 to provide additional selections for those functions.

[0030] In some implementations, the cursor button 144 can be used in conjunction with the display section 150 to select various self-test modes or display various test results corresponding to the selected self-test mode.

[0031] The display section 150 may include a display panel with multiple pixels, such as an LED or LCD display panel, and a display module including various circuits that enable the pixels of the display panel to display information. The display section is configured to display measurement results or self-test results of various self-test modes.

[0032] The display section 150 may also include a capacitive touchscreen with touchscreen buttons 160 and 162 for menu selection of various functions, parameters, or display settings for measurement or self-test functions. Menus can be activated together or separately from the touchscreen buttons and the mode selection for each measurement or self-test function. Other touchscreen buttons, such as a "Settings" button, are also possible and included within the scope of this disclosure. The setting buttons can be used to enable user configuration of various self-test functions, such as those selectable via rotating positions "Test 1," "Test 2," "Test 3," and "Calibration."

[0033] With the help of the plotting function of the processing unit or controller, the tester 100 can display graphical voltage and current measurements or self-test results, thereby providing the user with immediate feedback on the measurement or test status.

[0034] Figure 2The first part 202 of an example printed circuit assembly (“PCA”) 200 is schematically shown. (As...) Figure 2 As shown, PCA 200 includes a system-on-a-chip or ASIC chipset (“ASIC”) 210, a controller 220, and external circuitry 230. ASIC 210 is a semiconductor chip on which multiple functional units are integrated, and is also referred to as a system-on-a-chip device. Controller 220 is coupled to ASIC 210 and / or external circuitry 230 such that controller 220 controls the functionality and circuit connections and configuration of ASIC 210 and / or external circuitry 230 in measurement and self-test tasks. At least a portion of the circuitry elements on ASIC 210 and external circuitry 230 form the measurement circuitry of tester 100. Controller 220 is coupled to components of the measurement circuitry to control measurement and self-test functions and to receive and analyze data or signals generated during the operation of the measurement or self-test functions. For example, controller 220 is coupled to A / D converter 212 of ASIC 210 to read electrical signals flowing from external circuitry 230 to A / D converter 212.

[0035] The controller 220 is coupled to switches 232, 234 of external circuitry 230 to form a test path 240 (e.g., by connecting or disconnecting circuit components). This test path 240 couples the PTC circuit 242 between a DC signal source (e.g., a current source or voltage source) 214 and a ground terminal 125, which is connected to a COM terminal 124. Figure 1 The DC current source is located on ASIC 210 and is also referred to as an on-chip system DC current source or ASIC DC current source. When DC signal source 214 is activated to provide DC current to test path 240, a voltage signal is detected at node 244 adjacent to PTC circuit 242 (e.g., at a point directly connected to the terminal of PTC circuit 242) and fed to A / D converter 212 through a plurality of resistors coupled in series with each other to protect A / D converter 212. The digital output signal of A / D converter 212 is read by controller 220, which analyzes the reading to determine the state of PTC circuit 242, e.g., whether it is short-circuited or open. For example, controller 220 may compare the voltage reading of the detected voltage value to one or more predetermined threshold ranges of the voltage value. If the voltage reading is outside the threshold range of the voltage value, controller 220 may determine that PTC circuit 242 is involved in a malfunction. For example, the AD converter 212 can be used to read the voltage at signal source 214 (circuit arrangement not shown for simplicity), and the controller 220 can use the output digital signal of the AD converter 212 to determine whether the PTC circuit 242 is short-circuited or open when terminals 126 and 124 are short-circuited to each other.

[0036] In some implementations, controller 220 is coupled to user interface 104 ( Figure 1 The system can receive user selections for self-test mode and present the results of testing the PTC circuit 242 via, for example, display section 150 or other methods. For instance, if it is determined that the PTC circuit 242 includes a malfunction, an audio alarm can be triggered to remind the user to stop using the DMM for measurement tasks.

[0037] Figure 2 The entire PTC circuit 242, the series-connected PTC thermistor (PTC), and resistor R1 are shown to be included in test path 240, but this does not limit the scope of this disclosure. Controller 220 can control the test path to include only the component under test (PTC). For example, if only the PTC thermistor PTC of PTC circuit 242 is the PTC, then test path 240 can be configured to include only the PTC and exclude resistor R1 of PTC circuit 242. Alternatively, it is possible that the test path will be configured to include only resistor R1 and exclude the PTC. In some implementations, node 244 for voltage signal detection is configured to be adjacent to the component under test, for example, at a point where it is directly connected to a terminal of the component under test.

[0038] Switches 234 and 232 are controlled by controller 220 to automatically connect or disconnect test path 240 without user intervention. For example, in the formation of test path 240, controller 220 can control switch 234 to connect to input terminal 126 and common COM terminal 124 (… Figure 1 Short circuit between 126 and 124. Depending on the circuit design or configuration requirements of the DMM, additional protection functions (such as fuses or diodes) can be used with switch 234 in the circuit configuration of test path 240. In some implementations, user interaction can be enabled. For example, instead of controller 220 controlling switch 234 to connect or disconnect test path 240, controller 220 can also prompt the user to short circuit input terminal 126 (for voltage measurement mode) and COM terminal 124. Controller 220 can provide prompts to the user via display section 150 or via voice prompts. For example, when a customer is prompted to short circuit the test leads, Figure 2 The circuitry described can be used to determine whether the test lead itself is open.

[0039] Figure 3 The second part 302 of example PCA 200 is illustrated schematically. (As shown...) Figure 3As shown, a test path 310 is formed, which includes an RC series circuit 312 and a resistor divider circuit 314 series-coupled between an AC signal source (e.g., an AC current source or an AC voltage source) 320 and ground. The AC signal source 320 is located on the ASIC 210 and may be referred to as a system-on-chip (“SOC”) AC signal source. The resistor divider circuit 314 includes a first resistor unit RN1, which is selectively coupled to one of a plurality of second resistor units RN2, RN3, RN4, RN5 (or a resistor network) via a switch 316. The first resistor RN1 is adjacent to the RC series circuit 312, and the second resistors (e.g., RN5) are further away from the RC series circuit 312 than the first resistor RN1, and the first resistor RN1 has a larger resistance value than the second resistor RN5. In this way, more voltage will be allocated to the first resistor RN1, causing the voltage value read by the measurement component to drop to a low level to protect the measurement component. The resistor network comprises multiple second resistor units RN2, RN3, RN4, and RN5, each comprising a different resistance value, and which can be selectively coupled to the first resistor unit RN1 based on the voltage input to be measured, such that the voltage value at node 318 is within an acceptable range for feeding into the root mean square (RMS) to direct current (“DC”) converter 330 (RMS to DC converter). In some implementations, the ratio of the resistance values ​​of the first resistor unit RN1 to the second resistor units RN2, RN3, RN4, and RN5 is in the range of approximately 10:1 to 1000:1, including 10:1 and 1000:1. Figure 3 A resistor divider circuit 314 is shown in which the first resistor unit RN1 and the second resistor unit RN5 form a test path 310. In some implementations, the ratio of the resistance values ​​between the first resistor unit RN1 and the second resistor unit RN5 is approximately 10:1.

[0040] When the AC signal source 320 is activated to provide an AC signal to the test path 310, a voltage signal at node 318 adjacent to the RC series circuit 312 is detected and fed to the RMS-to-DC converter 330. The output of the RMS-to-DC converter 330 is then fed into the A / D converter 212. The controller 220 reads the voltage output of the A / D converter 212 and analyzes the voltage reading to determine the state of the RC series circuit 312, such as whether it is open. For example, the controller 220 can compare the voltage reading of the A / D converter's voltage output value with a predetermined threshold range of the voltage value. If the voltage reading is outside the threshold range of the voltage value, the controller 220 can determine that the RC series circuit 312 is malfunctioning.

[0041] In some implementations, controller 220 may also control switches 332, 334 to form a test path 340 that couples the resistor divider circuit 314 of the first resistor unit RN1 and the second resistor unit RN5 between a current source, an AC signal source 320 or a DC signal source (e.g., DC signal source 214), and ground. Test path 340 can be used to determine whether the resistor divider circuit 314 is involved in a functional malfunction. Note that when DC current source 214 is used for test path 340, the voltage signal at node 318 can be directly fed to A / D converter 212, thus bypassing RMS to DC converter 330.

[0042] In the specification and accompanying drawings, AC current source 320 and DC current source 214 are used as examples of power sources for providing electrical signals to the test path, which does not limit the scope of this disclosure. Other power sources (e.g., voltage sources) may also be used to form the test path, which is also included within the scope of this disclosure, as will be understood by one of ordinary skill in the art.

[0043] Figure 4 The third part 402 of example PCA 200 is illustrated schematically. (As shown) Figure 4 As shown, test or inspection paths 410 and 412 can be formed, each path including a component to be calibrated coupled between an inspection signal source and a signal reader (here, a controller). For example, Figure 4 The diagram illustrates a test path 410 including an AC test signal source (or generator) 420, a controller 220, and an RMS-to-DC converter 330 and an A / D converter 212 to be calibrated, coupled between the AC test signal source 420 and the controller 220 (as a signal reader). In some implementations, the AC test signal source 420 is coupled to apply an AC test voltage signal directly to the RMS-to-DC converter 330. The test path 412 includes a DC test signal source (or generator) 422, a controller 220, and an A / D converter 212 to be calibrated, coupled between the DC test signal source 422 and the controller 220 (as a signal reader). In some implementations, the DC test signal source 422 is coupled to apply a DC test voltage signal directly to the A / D converter 212.

[0044] Switches 424 and 426 can be controlled by controller 220 to connect or disconnect inspection paths 410 and 412. In some implementations, switch 428 is controlled by controller 220 to couple A / D converter 212 to either inspection path 410 or 412.

[0045] In some implementations, the AC check signal source 420 and the DC check signal source 422 are located external to the ASIC 210. For example, the AC check signal source 420 and the DC check signal source 422 can be independent components on the PCA 200, or they can be located on a separate ASIC or system-on-chip (“SOC”) chip, different from the ASIC 210, where the A / D converter 212 and the RMS-to-DC converter 330 are housed. Such external check signal sources can provide more accurate check signals for calibrating components on the ASIC 210 than signal sources located on the same ASIC 210. In some implementations, the AC check signal source 420 and the DC check signal source 422 each generate a corresponding voltage signal.

[0046] By applying a check signal with a known value to the component under test, such as the RMS-to-DC converter 330 and A / D converter 212 in check path 410 or the A / D converter 212 in check path 412, the voltage reading of the controller 220 can be compared with the known signal value to determine whether the voltage reading is accurate, which indicates the signal state of the component under test.

[0047] Figure 5 The illustration shows the operation of the tester 100 in an example scenario. In operation 510, the controller 220 receives a user selection of a self-test mode via a user interface 104 (e.g., test button 136 and / or control rotator 134). The self-test mode may include testing the connection status of a target component (e.g., whether the target component is short-circuited, disconnected, or properly connected) or inspecting the target component. In some implementations, the user selection of the test button 136 may enable the implementation of all test functions and all inspection functions, or the execution of a specified set of test functions or inspection functions, which can be configured by the user using the "Settings" function on the user interface 104.

[0048] In operation 520, controller 220 forms a test path or inspection path based on the received self-test mode. For example, when testing the connection state of the component, controller 220 controls the formation of a test path coupling the component under test between the on-chip system power supply and a low-voltage terminal. When testing the signal state of the component under test, controller 220 controls the formation of an inspection path coupling the component under test between a signal generator and controller 220. For example, as... Figure 2 As shown, the PTC circuit, which is the component under test, is coupled between the SOC DC source 214 and the ground terminal. Controller 220 controls switches 234 and 232 to form test path 230.

[0049] like Figure 3 As shown, the RC series circuit 312 is coupled between the SOC AC signal source 320 and the ground in the test path 310.

[0050] like Figure 4 As shown, the test path 412 includes the A / D converter under test on the ASIC 210 coupled between the external DC test signal source 422 and the controller 220.

[0051] In operation 530, controller 220 controls the activation of test or inspection signal sources in the formed test path. For example, signal sources 214, 320, 420, and 422 can each also be used to provide signals for other functions or circuit elements of PCA 200 (such as measurement functions). During transitions between various functions or circuit elements, signal sources can be decoupled or deactivated. For self-test or self-check functions, after the corresponding test or inspection path has been formed, controller 220 can control the activation of the corresponding signal sources 214, 320, 420, and 422.

[0052] In operation 540, controller 220 detects and analyzes electrical properties (e.g., voltage, current, resistance, etc.) at nodes adjacent to the component under test in the test or inspection path. For example, controller 220 compares the detected electrical properties with stored electrical property information to determine whether the component under test is functioning correctly or is experiencing a malfunction. Controller 220 can perform data analysis of the detected electrical properties locally, or it can work with a remote server or cloud computing capabilities to perform data analysis. For example, controller 220 can send the detected electrical properties to a remote server so that the remote server compares the detected electrical properties with stored electrical property information, and controller 220 can receive the analysis results back from the remote server.

[0053] In operation 550, controller 220 presents the results of the self-test operation via user interface 104. The self-test results can be presented in various ways, all of which are included in the specification. For example, the self-test results can be presented via display section 150 or via voice messages or alarms. Furthermore, if one or more safety components are detected to be malfunctioning, controller 220 can lock or disable the DMM's measurement functions to prevent any danger to the user.

[0054] The operation of the self-test or self-check function is further described using example implementations. Table 1 shows some example self-test or self-check modes or functions.

[0055] Table 1:

[0056] .

[0057] As shown in Table 1, in the first self-test example, check if the test lead is open. Test path 240 ( Figure 2The test path 240 is formed by controlling switch 234 to be in the off state (switch 234 open). The user is prompted (e.g., via user interface 104) to short-circuit the leads coupled to input terminal 126 and common terminal 124. DC signal source 214 is activated to apply current flowing through components 232, 242, 126, the test leads, and terminal 124 in the test path 240. The voltage at node 244 is detected, converted by A / D converter 212, and fed to controller 220 for analysis. Controller 220 calculates the resistance value by dividing the voltage detected at node 244 by the current value of signal source 214. The calculated resistance value is compared to a stored resistance threshold (e.g., 2Ω). If the calculated resistance value is less than the resistance threshold, the test lead is determined to be normal. If the calculated resistance value is equal to or greater than the resistance threshold, the test lead is determined to be faulty.

[0058] In the second self-test example, check whether the PTC circuit 242 is open (disconnected) or short-circuited. Test path 240 ( Figure 2 The test path 240 is formed by controlling switch 234 to be in the ON state (or by short-circuiting the test leads). DC signal source 214 is activated to apply current through components 232, 242, 126, 234, and 124 in the test path 240. The voltage at node 245 is detected, converted by A / D converter 212, and fed to controller 220 for analysis. Controller 220 calculates the resistance value by dividing the voltage detected at node 245 by the current value of signal source 214. The calculated resistance value is compared with a stored resistance threshold. In response to a calculated resistance value greater than, for example, a first resistance threshold of 5kΩ, PTC circuit 242 is determined to be open. In response to a calculated resistance value less than, for example, a second resistance threshold of 2.5kΩ, PTC circuit 242 is determined to be short-circuited.

[0059] In the third self-test example, check if the resistor network (RN1~RN5) is functioning correctly. Form test path 340 ( Figure 3 DC signal source 214 is activated to apply a DC voltage signal, for example, 2.5V, from the resistor divider circuit 314 to ground 125. The voltage value at node 318 is detected, converted by A / D converter 212, and fed to controller 220 for analysis. If the voltage value is within a threshold range of, for example, 2.0V-3.0V, the resistor divider circuit 314 is determined to be functioning correctly. Otherwise, a malfunction is determined to be involved in the resistor divider circuit 314.

[0060] In the fourth self-test example, check if the resistor network (RN1~RN5) and RC series circuit 312 are functioning correctly. Form test path 310 ( Figure 3AC signal source 320 is activated to apply an AC voltage signal, for example, 2.5V, from the RC series circuit 312 and the resistor divider circuit 314 to ground 125. The voltage value at node 318 is detected, converted by the RMS-to-DC converter 330 and the A / D converter 212, and fed to the controller 220 for analysis. If the voltage value is within a threshold range of, for example, 2.0V-3.0V, it is determined that the resistor divider circuit 314 and the RC series circuit are functioning correctly. Otherwise, it is determined that one or more of the resistor divider circuit 314 or the RC series circuit 330 are experiencing a malfunction.

[0061] In the fifth self-test example, the performance of AD converter 212 is checked. Test path 412 is formed ( Figure 4 A DC signal source 422 is activated to apply a DC voltage signal, for example, 1500V, to the A / D converter 212 of the ASIC via, for example, spring contacts and an analog switch (in the ASIC). The output signal of the A / D converter 212 is fed to the controller 220 for analysis. If the voltage value is within a threshold range, for example, 1450V-1550V, the A / D converter 212 is determined to be functioning correctly. Otherwise, the A / D converter 212 is determined to be malfunctioning.

[0062] In the sixth self-test example, the performance of the RMS-to-DC converter 330 is checked. Test path 410 is formed ( Figure 4 AC signal source 420 is activated to apply an AC voltage signal, such as 300V, 60Hz, to RMS-to-DC converter 330. The output of RMS-to-DC converter 330 is converted into a digital signal by A / D converter 212, which is fed to controller 220 for analysis. If the AC voltage value is within a threshold range (e.g., 290V-310V), RMS-to-DC converter 330 is determined to be functioning correctly. Otherwise, RMS-to-DC converter 330 is determined to be malfunctioning.

[0063] In the seventh self-test example, check the condition of the battery in DMM device 100. Form test path 412 ( Figure 4 The battery is coupled as a signal source 422 to apply a DC voltage signal to the A / D converter 212. The output signal of the A / D converter 212 is fed to the controller 220 for analysis. In response to a corresponding voltage value being less than a threshold of, for example, 3.3V, it is determined that the battery power is low for normal operation of the DMM device 100.

[0064] The controller 220 also stores records of each self-test or self-check operation, such as the test date. Based on the self-test or self-check interval set by the user, the controller 220 can indicate the next self-test due date or the number of days remaining until the next self-test due date.

[0065] Furthermore, the controller 220 can calculate additional electrical properties of the component under test based on the detected electrical properties, and compare the calculated electrical properties with stored electrical property information to determine the electrical state of the component under test. For example, when a current source is used as a signal source in the test path (e.g., Figure 2 In the case of 214), controller 220 can calculate the resistance value based on the voltage value detected at node 245 and the current value of current source 214, and can compare the calculated resistance value with the corresponding stored resistance value (e.g., threshold A of 5kΩ or threshold B of 2.5kΩ) to determine whether the PTC circuit is open or short-circuited.

[0066] The switches 232, 234, 332, 318, 334, 424, 426, and 428 involved in forming the test path can each be implemented as analog switches, such as switches based on the spring contacts of the control rotator 134, electromechanical switches enabled by the control relay 132, or transistors, such as p-MOS or n-MOS transistors controlled by electrical signals on their gate terminals. The scope of this specification is not limited by the type of switches used in forming the test path.

[0067] Figure 6 An example of the self-test results is shown by displaying section 150. (See section 150 for details.) Figure 6 As shown, test lead inspection refers to checking the test leads by shorting the voltage input terminal and the common COM terminal. Figure 2 The PTC circuit 242 is tested in self-test mode (as shown in the diagram), and the result of the self-test mode is "pass", which indicates that no functional failure was found. Figure 6 It is also shown that the A / D converter 212 ( Figure 4 During the check, a DC check voltage of 1500V (or an analog 1500V voltage) is applied to the A / D converter 212, and the controller 220 obtains a DV voltage of 1500V. Figure 6 The diagram also illustrates that during the inspection of the RMS-to-DC converter 330 and the A / D converter 212, a 300.0V, 50Hz AC test voltage (or a simulated 300.0V AC voltage) is applied to the RMS-to-DC converter 330, and the controller 220 obtains the 300.0V, 50Hz AC voltage. Therefore, the self-test result includes both quantitative components (e.g., measured electrical properties) and qualitative components (e.g., pass or fail) to provide the user with convenient readings of the health or safety of the component under test in the circuitry of the tester.

[0068] It should be understood that the various embodiments described above can be combined to provide further embodiments of the tester 100. Various aspects of the embodiments can be modified and other changes can be made to the embodiments based on the above detailed description without departing from the spirit or scope of this disclosure.

[0069] For the purposes of this disclosure, unless otherwise indicated, the phrase “A and B” is non-restrictive and means one or more of (A) and one or more of (B); the phrase “A or B” is non-exclusive and means one or more of (A), one or more of (B), or one or more of (A and B); “A and / or B” means one or more of (A), one or more of (B), or one or more of (A and B); the phrase “at least one of A and B” means at least one of (A) and at least one of (B); the phrase “one or more of A and B” means one or more of (A) and one or more of (B); the phrase “at least one of A or B” means at least one of (A), at least one of (B), or at least one of (A and B); and the phrase “one or more of A or B” means one or more of (A), one or more of (B), or one or more of (A and B). For example, by extension, the phrase "at least one of A, B, or C" means at least one of (A), at least one of (B), at least one of (C), at least one of (A and B), at least one of (A and C), at least one of (B and C), or at least one of (A, B, and C). In the foregoing, A, B, and C represent any form or type of element, feature, arrangement, component, structure, aspect, action, step, or such.

[0070] As used herein, the terms “first,” “second,” “third,” etc., may be used interchangeably to distinguish one component from another, but are not intended to indicate the position, order, sequence, or importance of a single component.

[0071] It is used to distinguish one component from another, and is not intended to indicate the position, order, sequence, or importance of the components.

[0072] Further aspects of this disclosure are provided by the subject matter of the following provisions concerning test instruments, methods, and computer-readable media.

[0073] A tester for measuring electrical properties includes a controller that performs self-testing along a test path. The tester optionally includes a user interface or measurement circuitry, which optionally includes a component under test (SUB-D) or a signal source. The controller is optionally configured, for example, in response to user input from the user interface, to form a test path by coupling the SUB-D between the signal source and terminals of the tester.

[0074] The controller is optionally configured to detect the electrical properties at nodes adjacent to the component under test (SUB) in the test path and determine the result of the self-test based on the electrical properties at the nodes. Nodes are optionally coupled to the controller via an analog-to-digital converter (ADC), which is optionally coupled to at least one series resistor. The signal source can be a DC signal source. The SUB optionally includes a resistive voltage divider circuit. Nodes may optionally be located between two resistors in the resistive voltage divider circuit. The signal source can be a DC signal source. The SUB optionally includes a positive temperature coefficient (PTC) circuit, and the PTC circuit optionally includes a PTC thermistor and a resistor coupled in series.

[0075] The test path can optionally be configured to short-circuit the input terminals and common terminal of the tester. The test path can optionally include, for example, a switch controllable by a controller. The switch can be positioned between the input terminals and the common terminal. The component under test can optionally include an RC series circuit, and the signal source can be an AC signal source. The terminals of the tester can serve as a reference node in the tester. The test path can optionally include a resistor divider circuit coupled between the RC series circuit and the reference node. The resistor divider circuit can optionally include a first resistor adjacent to the RC series circuit and a second resistor further away from the RC series circuit than the first resistor. The resistance value of the first resistor can be greater than the resistance value of the second resistor. The controller can optionally be configured to detect the electrical properties at the node between the first and second resistors, and an RMS-to-DC converter can optionally be coupled between this node and the controller.

[0076] The component under test (DUT) may optionally be located on a semiconductor chip. A signal source may optionally be located outside the semiconductor chip and may optionally be configured to generate a first voltage signal. A controller may be configured to read a second voltage signal at a terminal of the tester. The DUT may optionally include an RMS-to-DC converter. The signal source may be an AC signal source. The AC signal source may optionally be configured to apply the first voltage signal directly to the RMS-to-DC converter, which may optionally be coupled to the controller via an analog-to-digital converter (ADC). The DUT may optionally include an ADC, and the signal source may optionally be a DC signal source. The DC signal source may optionally be configured to apply the first voltage signal directly to the ADC.

[0077] A method for performing a self-test includes performing a self-test on any tester as described above. The method may include any of the following steps: receiving user input; controlling one or more switches based on the user input to couple a signal source in the tester to the component under test in the tester's measurement circuitry; or performing a self-test based on electrical properties at a node adjacent to the component under test.

[0078] The method optionally includes the step of receiving user input via a user selection mechanism on the user interface of the tester. The method optionally includes the step of prompting the user to short-circuit a first test lead coupled to a measurement terminal of the tester to a second test lead coupled to a common terminal of the tester to complete a self-test. The method optionally includes the steps of: detecting electrical properties at a node adjacent to the component under test; or determining the result of the self-test based on the electrical properties. The method optionally includes the steps of: calculating another electrical property based on the electrical properties; or comparing the other electrical property with stored electrical property information. The signal source in the method can be a current source. The electrical property can be voltage, and the other electrical property can be resistance. The method optionally includes the step of presenting the self-test result via the user interface of the tester. The self-test result optionally includes quantitative or qualitative components.

[0079] Finally, one or more non-transitory computer-readable media storing instructions executable by one or more processors are disclosed to implement computer-implemented methods as set forth in any of the foregoing provisions.

[0080] Based on the detailed description above, these and other modifications can be made to various embodiments of the tester. For example, suppose the tester is a battery tester. In that case, with Figure 1 Compared to tester 100, the tester will have different circuitry and configuration. The battery tester may have more or fewer terminals than tester 100. To perform some self-testing in the battery tester, the controller only needs to control internal switches to form test paths (e.g., from the component under test to an internal signal source) without needing to be connected to any terminals of the battery tester. Since the circuitry in different testers may differ, the implementation details, purpose, process, nodes, preset attributes, standards, etc., of self-testing can be adapted based on this disclosure without excessive experimentation.

[0081] Generally, the terminology used in the following claims should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be interpreted to include all possible embodiments and the full scope of equivalents enjoyed by such claims. Therefore, the claims are not limited by this disclosure.

Claims

1. A tester with a self-testing function, characterized in that, include: User interface; A measurement circuit, which includes the component under test and a signal source; as well as The controller, coupled to the user interface and measurement circuitry, is configured to perform self-testing in response to user input from the user interface along a test path formed by coupling the component under test between the signal source and the terminals of the tester.

2. The tester with self-test function according to claim 1, wherein the controller is configured to detect the electrical properties at nodes adjacent to the component under test in the test path, and determine the result of the self-test based on the electrical properties at the nodes.

3. The tester with self-test function according to claim 2, wherein the node is coupled to the controller via an analog-to-digital converter, the analog-to-digital converter being coupled to at least one series resistor.

4. The tester with self-test function according to claim 2, wherein the signal source is a DC signal source, and the component under test includes a resistor divider circuit; and wherein the node is located between the two resistors of the resistor divider circuit.

5. The tester with self-test function according to any one of claims 1-4, wherein the signal source is a DC signal source, and the component under test includes a positive temperature coefficient (PTC) circuit; and wherein the PTC circuit includes a PTC thermistor and a resistor coupled in series.

6. A tester with self-test functionality according to any one of claims 1-4, wherein the test path is configured to short-circuit the input terminal and the common terminal of the tester, and wherein the test path includes a switch controlled by a controller, the switch being coupled between the input terminal and the common terminal.

7. The tester with self-test function according to any one of claims 1-4, wherein the component under test includes an RC series circuit and the signal source is an AC signal source.

8. The tester with self-test function according to claim 7, wherein the terminals of the tester are reference nodes in the tester, and the test path includes a resistor divider circuit coupled between the RC series circuit and the reference node.

9. The tester with self-test function according to claim 8, wherein the resistor divider circuit includes a first resistor adjacent to the RC series circuit and a second resistor farther from the RC series circuit than the first resistor, and wherein the resistance value of the first resistor is greater than the resistance value of the second resistor.

10. The tester with self-test function according to claim 9, wherein the controller is configured to detect electrical properties at a node between the first resistor and the second resistor, and an RMS to DC converter is coupled between the node and the controller.

11. The tester with self-test function according to any one of claims 1-4, wherein the component under test is located on a semiconductor chip, the signal source is located outside the semiconductor chip and configured to generate a first voltage signal, and the controller is configured to read a second voltage signal at a terminal of the tester.

12. The tester with self-test function according to claim 11, wherein the component under test includes an RMS-to-DC converter and the signal source is an AC signal source; and wherein the AC signal source is configured to directly apply a first voltage signal to the RMS-to-DC converter, the RMS-to-DC converter being coupled to the controller via an analog-to-digital converter.

13. The tester with self-test function according to claim 11, wherein the component under test includes an analog-to-digital converter and the signal source is a DC signal source; and wherein the DC signal source is configured to directly apply a first voltage signal to the analog-to-digital converter.

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