JP2015114166A - Measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring apparatus capable of preventing carrying heavy current even if switching means fails to switch electrical parameters to measure a current.SOLUTION: A measuring apparatus 10 includes: an input terminal section 21 electrically connected to a connection terminal T1 of a test lead T; a measuring processing unit 22 performing a measuring process for measuring electrical parameters of a measuring target on the basis of electric power input from the input terminal section 21; switching means 24 switching the electrical parameters subjected to the measuring process in the measuring processing unit 22; switch means 28 allowing conduction of the electric power toward the measuring processing unit 22 via the input terminal section 21 in an ON-state, and cutting off the electric power in the OFF-state; and control means 23 controlling the switch means 28 to operate, the control means 23 exerting a control to turn off the switch means 28 in advance if the measuring processing unit 22 measure a current among the electrical parameters, and to turn on the switch means 28 if the switch means 28 in the OFF-state is actuated to be turned on.

Description

  The present invention relates to a measuring apparatus for measuring electrical parameters such as current, voltage and resistance.

  As a multimeter for measuring electrical parameters such as current, voltage and resistance, there is one as shown in Patent Document 1, for example. The multimeter shown in Patent Document 1 includes a rotary switch having a knob, and the rotary switch can be rotated by holding the knob. Then, by rotating the rotary switch to the position indicated by the knob, it is possible to measure electrical parameters such as current and voltage on a desired scale.

  Here, although the multimeter of patent document 1 is provided with the several input terminal hole for inserting the pin plug of a test lead, this input terminal hole is specific input by the shutter board | substrate interlock | cooperated with rotation of a rotary switch. Only the terminal hole is open.

Japanese Patent Laid-Open No. 10-246737

  By the way, in the multimeter disclosed in Patent Document 1, it is possible to close an input terminal hole unrelated to measurement with a shutter plate. However, if it is forgotten to switch the rotary switch to the voltage measurement position after measuring the current, it will be electrically connected to the live part in a low input impedance state. Then, an unexpected large current may flow to the multimeter for the user.

  In addition, when such a large current flows, the fuse is blown, so that troubles such as replacement of the fuse for remeasurement occur.

  The present invention has been made on the basis of the above circumstances, and its object is to provide a measuring device capable of preventing a large current from flowing even if the switching means forgets to perform switching so as to perform voltage measurement. I will try.

  In order to solve the above-mentioned problem, according to a first aspect of the present invention, there is provided a measuring apparatus for measuring an electrical parameter of a measurement object, which is electrically connected to a connection terminal of a test lead that contacts the measurement object. An input terminal unit, a measurement processing unit that performs a measurement process for measuring an electrical parameter to be measured based on electric power input from the input terminal unit, and a switching unit that switches an electrical parameter that is measured by the measurement processing unit And switch means for allowing conduction of power toward the measurement processing section through the input terminal section in the on state, and for switching off the conduction of power in the off state, and control means for controlling the operation of the switch means. In the case where the measurement processing unit performs current measurement among the electrical parameters, the control means turns off the switch means in advance and turns on the switch means in the off state. When the operation of is made performs control to an on state, there is provided measuring apparatus characterized by.

  In addition, according to another aspect of the present invention, in the above-described invention, the control unit performs control to turn off the switch unit when the current measured by the measurement processing unit continues for a predetermined time or less. Is preferable.

  Further, according to another aspect of the present invention, in the above-described invention, it is preferable that the control means informs that the current measurement is performed by operating the notification means when performing the current measurement.

  According to the present invention, it is possible to provide a measuring apparatus capable of preventing a large current from flowing even when the switching means forgets to perform switching so as to perform voltage measurement.

It is a block diagram showing a schematic structure of a measuring device concerning one embodiment of the present invention. It is a top view which shows the structure of the measuring apparatus of FIG. It is a partial top view which shows the structure of the measuring apparatus of FIG. 1, and is a figure which shows an example in the state by which the hole part was block | closed with the shutter board | plate.

  Hereinafter, a measuring apparatus 10 according to an embodiment of the present invention will be described with reference to the drawings.

<About a schematic structure of the measuring apparatus 10>
FIG. 1 is a block diagram showing a schematic configuration of the measuring apparatus 10. FIG. 2 is a plan view showing the configuration of the measuring apparatus 10.

  The measuring device 10 is a digital multimeter capable of measuring electrical parameters such as current, voltage and resistance. The apparatus main body 20 of the measuring apparatus 10 includes an input terminal unit 21, a measurement processing unit 22, a control unit 23, an operation unit 24, a storage unit 25, a display unit 26, and an overcurrent protection unit 27. In addition, a switch unit 28 is provided.

  The input terminal portion 21 includes a portion into which the connection terminal T1 of the test lead T is inserted, such as a banana plug. The input terminal portion 21 includes a reference terminal portion 21a (COM terminal), a current measurement terminal portion 21b, and a voltage measurement terminal portion 21c. Note that the voltage measurement terminal unit 21c may be capable of detecting resistance, conductance, diode measurement, capacitance, electrical continuity, temperature, and the like in addition to voltage. In the configuration shown in FIG. 1, two current measurement terminal portions 21b having different measurement ranges are provided. However, a configuration in which only one current measurement terminal portion 21b is provided or a configuration in which three or more current measurement terminal portions 21b are provided may be employed.

  The measurement processing unit 22 measures the electrical parameter (electric power) acquired from the test lead T via the input terminal unit 21 and the electrical parameter of the measurement target (live power unit) based on the control by the control unit 23. The measurement result is output to the control unit 23.

  In addition, the control unit 23 performs overall control of the measurement apparatus 10, but performs a process of displaying the measurement result output from the measurement processing unit 22 on the display unit 26 or storing the measurement result in the storage unit 25. . The control unit 23 corresponds to the control unit, but other configurations of the apparatus body 20 may be included in the components of the control unit. Examples of such other configurations include the storage unit 25 and the like.

  The operation unit 24 includes a rotary switch 241 and various operation buttons 242. The operation unit 24 outputs an operation signal corresponding to the position of the rotary switch 241 and an operation signal corresponding to the button operation of various operation buttons 242 to the control unit 23. The operation unit 24 corresponds to switching means.

  In addition, the storage unit 25 is a part that temporarily stores a calculation result in the control unit 23 such as a ROM, a RAM, or a flash memory, or stores a measurement result based on an instruction in the control unit 23. Furthermore, the storage unit 25 is a part that stores a processing program operating in the control unit 23 and various types of processing data. Further, for example, all or part of the display device is constituted by a display device such as an LCD (Liquid Crystal Display). The display unit 26 displays the result of each process executed by the control unit 23 on the screen. The display unit 26 is exposed on an operation surface 100a of the housing 100 described later.

  The overcurrent protection unit 27 has a fuse, and protects the device main body 20 against overcurrent conduction from the input terminal unit 21.

  The switch unit 28 connects or disconnects a circuit from the input terminal unit 21 to the measurement processing unit 22 based on control by the control unit 23. The switch unit 28 corresponds to switch means. The switch portion 28 has a switch button 28a, and the switch button 28a is exposed on an operation surface 100a of the housing 100 described later. Further, the switch unit 28 disconnects the circuit from the input terminal unit 21 toward the measurement processing unit 22 when the current is measured (turns off), but the input is performed when the switch button 28a is pressed. Control is performed by the control unit 23 so as to connect the circuit from the terminal unit 21 to the measurement processing unit 22 (turn on). However, after the measurement is started, when the state where the measured current is a certain value or less continues for a predetermined time, the switch unit 28 disconnects the circuit from the input terminal unit 21 toward the measurement processing unit 22. It is controlled by the control unit 23.

  The “constant value” of the current includes, for example, 0.1% or less of the full scale in the measurement range for measuring the current, but other values may be used. The “predetermined time” for disconnecting the circuit is preferably shorter than the work time for the operator to move from one measurement object to the next measurement object. Such “predetermined time” is preferably 1 second or less, for example. However, since a state in which the current value is periodically appeared in alternating current, the “predetermined time” is preferably longer than 1/60 of a commercial alternating current power supply, for example. Such “predetermined time” includes, for example, about 0.3 seconds.

  The switch unit 28 includes a semiconductor switch element such as a MOSFET (metal-oxide-semiconductor field-effect transistor) made of SiC (silicon carbide). As semiconductor switches, there are various semiconductor switches such as switches using bipolar transistors and diode switches such as PIN diodes (p-intrinsic-n Diodes) in addition to those using FETs such as the MOSFETs described above. Can be used. Various switches other than the semiconductor switch (for example, a mechanical switch, a switch using an electrostatic force or an electromagnetic force, etc.) may be used.

  As shown in FIG. 2, the entire apparatus main body 20 is covered with a housing 100. On the operation surface 100a of the housing 100, the above-described display unit 26 is provided so as to be visible.

  Further, the operation knob 241 a of the rotary switch 241 is rotatably attached to the housing 100 through the hole 101. The rotary switch 241 has an operation knob 241a, and the rotary switch 241 can be rotated by gripping this 241a. Such rotation enables the rotary switch 241 to be positioned at a specific rotational position. When the rotation position is reached, a desired electrical parameter can be measured in the set range. Note that the rotational position can be associated with measurement of various electrical parameters. Examples of such electrical parameters include DC voltage, AC voltage, simultaneous measurement of DC voltage and AC voltage, DC current, There are various types including AC current, simultaneous measurement of DC current and AC current, resistance, conductance, capacitance, frequency, diode measurement, change of measurement range, detection of electrical continuity, temperature and the like.

  The operation surface 100a of the housing 100 is provided with a hole 102 into which the connection terminal T1 of the test lead T is inserted, and the input terminal portion 21 is exposed from the hole 102 to the operation surface 100a.

  FIG. 3 is a partial plan view showing the configuration of the measuring apparatus 10, and shows an example of a state where the hole 102 is closed by the shutter plate 30. As shown in FIG. 3, the hole 102 can be closed by the shutter plate 30. The shutter plate 30 is always open without blocking the reference terminal portion 21a. However, the shutter plate 30 blocks the current measurement terminal portion 21b and the voltage measurement terminal portion 21c that are not related to the measurement indicated by the rotational position of the operation knob 241a. Therefore, the shutter plate 30 is interlocked with the rotary switch 241 described above.

  Further, a switch button 28a constituting the switch unit 28 is provided on the operation surface 100a. The switch button 28a is provided so that it can be pushed in by the user. When the switch button 28a is pushed, the switch unit 28 starts the measurement and continues until the state where the measured current is below a certain value continues for a predetermined time. To the measurement processing unit 22 is connected.

  In addition to the above-described configuration, when current measurement is further performed, a configuration may be provided that includes notification means for notifying that current measurement is performed based on control by the control unit 23. As such a notification means, for example, a sound such as a buzzer is generated, the display unit 26 is displayed in a predetermined color different from normal, or the display or color of the display unit 26 is periodically changed ( An example of this change includes a blinking one), and vibration may be applied by a vibration motor.

<About action>
The operation of the measuring apparatus 10 having the above configuration will be described below. When measuring an electrical parameter using the measuring apparatus 10, the user holds the operation knob 241a of the rotary switch 241 and rotates the rotary switch 241 to be positioned at a desired rotational position. Then, the shutter plate 30 closes the input terminal portion 21 that is not related to measurement. Specifically, the shutter plate 30 always opens without closing the reference terminal portion 21a, but closes the unrelated ones of the current measurement terminal portion 21b and the voltage measurement terminal portion 21c.

  For example, when the operation knob 241a of the rotary switch 241 is located at the rotation position for measuring the current, the shutter plate 30 opens the current measurement terminal portion 21b of the measurement range corresponding to the rotation position. The current measurement terminal portion 21b and the voltage measurement terminal portion 21c in a measurement range that are not related to the above are blocked. Further, when the operation knob 241a of the rotary switch 241 is positioned at the rotation position for measuring the voltage, the shutter plate 30 closes the current measurement terminal portion 21b. Then, the user connects the test lead T to the reference terminal portion 21a, the current measurement terminal portion 21b, and the voltage measurement terminal portion 21c that are not closed (open) by the shutter plate 30. Insert the connection terminal T1. Thereby, it will be in the state which can measure a measuring object (live power part).

  Thus, since the shutter plate 30 blocks the input terminal portion 21 that is not related to measurement, the connection terminal T1 of the test lead T is prevented from being inserted into the wrong input terminal portion 21, thereby erroneous measurement. Should not be done.

  However, problems arise in the following cases. That is, for example, if the user forgets to switch the operation knob 241a of the rotary switch 241 to the rotational position for measuring the voltage when trying to measure the voltage after measuring the current, a low input for measuring the current. In the state of impedance, it is electrically connected to the measurement target (the live part). Then, an unexpected large current flows through the apparatus main body 20. As a result, there is a problem that the fuse of the overcurrent protection unit 27 is blown.

  In this case, the user should normally position the operation knob 241a of the rotary switch 241 at the rotational position where the voltage is measured. However, if the rotation operation is forgotten, the shutter plate 30 is in a state of closing the voltage measurement terminal portion 21c while the current measurement terminal portion 21b is open. For this reason, erroneous measurements cannot be prevented.

  On the other hand, in the present embodiment, when current measurement is performed, the switch unit 28 is in a state of disconnecting a circuit from the input terminal unit 21 toward the measurement processing unit 22. When the switch button 28a is pressed, the switch unit 28 is controlled to connect a circuit from the input terminal unit 21 to the measurement processing unit 22 based on the control by the control unit 23. When the state where the measured current is below a certain value continues for a predetermined time after the measurement is started, the switch unit 28 is connected to the measurement processing unit from the input terminal unit 21 based on the control by the control unit 23. The circuit going to 22 is turned off.

  For this reason, even if the user tries to measure the voltage, unless the switch button 28a associated with the current measurement is pressed, the measurement apparatus 10 cannot measure (the measurement is impossible). Thereby, the user notices that he has forgotten to switch the operation knob 241a of the rotary switch 241 to the rotation position for measuring the voltage. Then, the user disconnects the connection terminal T1 of the test lead T from the voltage measurement terminal portion 21c, and switches the operation knob 241a of the rotary switch 241 to the rotation position for measuring the voltage. Thereafter, the user inserts the connection terminal T1 into the current measurement terminal portion 21b.

  Thereafter, the user can correctly measure the current of the measurement target (the live part) by pressing the switch button 28a. In general, when measuring current, a clip-type test lead is used, and a clip portion of the clip-type lead sandwiches a measurement target. Therefore, while holding the measuring device 10 with one hand, the switch button 28a can be pushed with the other hand, and the switch button 28a can be pushed in without difficulty.

  Here, in contrast to the above, when measuring the current after measuring the voltage, even if the user forgets to switch the operation knob 241a of the rotary switch 241 to the rotational position for measuring the current. In the apparatus main body 20, since the input impedance is high for voltage measurement, there is no particular problem such as the fuse of the overcurrent protection unit 27 being blown. In this case, the user immediately notices his / her own measurement error by looking at the electrical parameters displayed on the display unit 26, since such a problem that the fuse is blown does not occur. Therefore, in this case, the switch unit 28 is not in a state of disconnecting the circuit from the input terminal unit 21 toward the measurement processing unit 22.

  As described above, when the voltage is measured, it is not necessary to push the switch button 28a, but the switch button 28a is pushed only when the current is measured. As a result, when the voltage cannot be measured even though the voltage is being measured, it can be realized that the operation knob 241a of the rotary switch 241 has been forgotten to be changed to the rotational position where the voltage is measured.

<About effect>
According to the measuring apparatus 10 having the above configuration, the control unit 23 turns off the switch unit 28 in advance when the measurement processing unit 22 performs current measurement among the electrical parameters. When the switch unit 28 is turned on in the off state, the control unit 23 controls the switch unit 28 to be in the on state, and the measurement processing unit 22 performs current measurement. For this reason, for example, even if the operation knob 241a is operated after the current is measured and it is forgotten to switch the rotary switch 241 so as to perform voltage measurement, as long as the switch button 28a is not pressed, the apparatus main body 20 is not expected. It is possible to prevent a large current from flowing. Therefore, it is possible to prevent the fuse of the overcurrent protection unit 27 from being unexpectedly blown.

  Even if the user tries to measure the voltage, the measurement apparatus 10 cannot measure unless the switch button 28a associated with the current measurement is pressed. Since such a state incapable of measurement occurs, the user can notice that the operation knob 241a of the rotary switch 241 has forgotten to be switched to the rotation position for measuring the voltage.

  Further, when the current is measured, the switch button 28a may be pushed in. When the push is performed, a circuit from the input terminal unit 21 to the measurement processing unit 22 is controlled based on the control by the control unit 23. Is connected. Therefore, the user can easily perform current measurement.

  Further, the user can distinguish between the case where the voltage measurement is performed and the case where the current measurement is performed because the operation of the measurement apparatus 10 is different. Therefore, it is possible to raise awareness of current measurement that may cause a large current to flow through the apparatus main body 20.

  Further, in the present embodiment, the control unit 23 performs control to turn off the switch unit 28 when a state in which the current measured by the measurement processing unit 22 is equal to or less than a predetermined value continues for a predetermined time. For this reason, when the current measurement is newly performed, an operation of pressing the switch button 28a to turn on the switch unit 28 is necessary, and the user can be conscious of performing the current measurement. Further, when the state where the current is equal to or less than a predetermined value continues for a predetermined time, the control unit 23 controls the switch unit 28 to be in the OFF state, so that the user leads to various measurement objects (live parts) one after another. In the case where the measurement is performed with T in contact, the apparatus main body 20 can be protected from a large current even if the user forgets to switch the rotary switch 241 from the voltage measurement to the current measurement.

  Further, in the present embodiment, when performing current measurement, the control unit 23 can also be configured to notify that the current measurement is performed by operating the notification means. In the case of such a configuration, it is possible to increase the user's recognition that the apparatus main body 20 is set to perform current. As a result, when the voltage is intended to be measured, it becomes possible to more reliably notice that the rotary switch 241 has been forgotten.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be variously modified in addition to this. This will be described below.

  In the above-described embodiment, although the current measurement is enabled by pressing the switch button 28a, the control unit 23 switches the switch unit so that the switch unit is turned off when the current is below a certain value for a predetermined time. 28 is activated. However, the operation may be different from the above operation. For example, when the switch button 28a is kept pressed, the control unit 23 may control the switch unit 28 so that the switch unit 28 is not turned off even if the current is kept below a certain value for a predetermined time or longer. good.

  Moreover, in the above-mentioned embodiment, the switch part 28 shall be pushed in, when measuring an electric current. However, a switch unit different from the switch unit 28 may be provided. For example, a switch unit that is pushed in when measuring the voltage may be provided separately. In this case, since the switch unit 28 that is pushed in when measuring the current and the switch unit that is pushed in when measuring the voltage exist separately, the user presses the voltage measurement switch in order to measure the voltage. Nevertheless, if the user forgets to switch the rotary switch 241 so as to perform voltage measurement, for example, the above-described notification means is operated to notify that the user has forgotten to switch the rotary switch 241. good.

  Moreover, in the above-mentioned embodiment, what is shown in FIG. 1 is disclosed as the measuring apparatus 10 (apparatus main body 20). However, you may comprise as follows. That is, a circuit for detecting a voltage is provided between the reference terminal portion 21a and the current measuring terminal portion 21b. When a voltage larger than a predetermined voltage (for example, 5V) is detected, the input terminal portion 21 can be pressed even if the switch button 28a is pressed. You may comprise so that the circuit which goes to the measurement process part 22 may not be connected.

  In the above-described embodiment, a push-type button that exists on the operation surface 100a is disclosed as the switch button 28a. However, any switch button 28a may be used. For example, various switches such as a dial type switch and a slide type switch can be used.

  In the above-described embodiment, the measurement device 10 is a digital multimeter capable of measuring various electrical parameters. However, the measuring device may be an analog display type multimeter.

DESCRIPTION OF SYMBOLS 10 ... Measuring apparatus, 20 ... Apparatus main body, 21 ... Input terminal part, 21a ... Reference terminal part, 21b ... Current measuring terminal part, 21c ... Voltage measuring terminal part, 22 ... Measurement processing part, 23 ... Control part (control) , 24 ... operation unit (corresponding to switching means), 25 ... storage unit, 26 ... display unit, 27 ... overcurrent protection unit, 28 ... switch unit (corresponding to switch means), 28a ... switch button, 30 ... shutter plate, 100 ... housing, 100a ... operation surface, 101, 102 ... hole, 241 ... rotary switch, 242 ... operation button, T ... test lead, T1 ... connection terminal

Claims (3)

A measuring device for measuring an electrical parameter of a measurement object,
An input terminal portion that is electrically connected to a connection terminal of a test lead that comes into contact with a measurement object;
A measurement processing unit that performs a measurement process of measuring an electrical parameter of the measurement target based on electric power input from the input terminal unit;
Switching means for switching the electrical parameter to be measured by the measurement processing unit;
Switch means for allowing conduction of power toward the measurement processing section through the input terminal section in the on state, and blocking the conduction of power in the off state;
Control means for controlling the operation of the switch means;
Comprising
In the case where the measurement processing unit performs current measurement among the electrical parameters, the control means sets the switch means in the off state in advance and sets the switch means in the on state in the off state. If it is made, control to turn on the above,
A measuring device. The measuring device according to claim 1,
The control means performs control to turn off the switch means when a state in which the current measured by the measurement processing unit is below a certain value continues for a predetermined time.
A measuring device. The measuring device according to claim 1 or 2,
In the case where the current measurement is performed, the control unit activates the notification unit to notify that the current measurement is performed.
A measuring device.

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