JP6121278B2 - Switching control circuit and measuring device - Google Patents

Description

  The present invention includes, for example, a switching control circuit for controlling on / off of a plurality of switching elements constituting a signal switching device that switches and supplies current from one power supply unit to a plurality of measurement objects, and the switching control circuit. It relates to a measuring device.

  As this type of switching control circuit, a control unit that controls a first switching unit as a signal switching unit disclosed in Patent Document 1 below is known. The first switching unit is composed of a switching element such as a relay or an analog switch, and includes a plurality of probe units connected to a plurality of measurement objects, and a lead wire connected to a power source unit that generates a measurement current. It is connected to the. The control unit performs control on the first switching unit and shifts the switch elements constituting the first switching unit to an on state or an off state, thereby measuring each of the plurality of probe units from the power source unit. Supply the current for switching.

  In the above-mentioned patent document, although not specified, for each switch element constituting the first switching unit, a current for measurement flows (energized state), from an on state to an off state, or an off state. So-called hot switching, which is controlled from the ON state to the ON state, is not preferable. For this reason, the control unit waits for the elapse of a period required for the continuity generated when the current for measurement is stopped to the power supply unit to become almost zero, and then turns the switch element in the on state to the off state. In addition to the control, other switch elements in the off state are controlled in the on state. It should be noted that the period during which this continuity is almost zero varies under the influence of the inductance, capacitance, and pure resistance of the current path through which the measurement current flows. For this reason, when performing on / off control for each switch element constituting the first switching unit, normally, the maximum of these periods is obtained in advance by simulation or experiment, and the power supply unit is Thus, hot switching is avoided by controlling the switch element after a certain period longer than the maximum period elapses after the measurement current is stopped.

JP 2008-46060 A (page 5-7, FIG. 1-2)

  However, the conventional switching control circuit described above has the following problems to be improved. That is, in this switching control circuit, each time the switch element constituting the signal switching device is controlled, the switch waits for a certain period of time to elapse after the measurement current is stopped for the power supply unit. It is necessary to control the element. For this reason, the subject which should be improved that the time when performing control with respect to the switch element which comprises a signal switching device in multiple times becomes long exists.

  The present invention has been made in order to improve such a problem, and a switching control circuit capable of shortening the time required to execute a plurality of times of control on switch elements constituting a signal switching device, and a measurement provided with the switching control circuit. The main purpose is to provide a device.

  In order to achieve the above object, the switching control circuit according to claim 1 includes a plurality of switch elements, and is disposed between a power supply unit that outputs a measurement current and a plurality of measurement objects, In the signal switch configured to be able to supply the measurement current by connecting one measurement object selected from the plurality of measurement objects to the power supply unit by controlling on / off of the switch element A switching control circuit including a processing unit that performs the on / off control for the plurality of switch elements, the detection control unit including a detection unit that detects the measurement current output from the power supply unit to the signal switcher The processing unit has a current threshold value defined in advance and a current value of the measurement current detected by the detection unit after the control for stopping the output of the measurement current is performed on the power supply unit. By comparing the value, when the current value of the current for measurement is detected that is below the current threshold, performing the on-off control for the plurality of switching elements.

  According to a second aspect of the present invention, the switching control circuit includes a plurality of switch elements, and is disposed between a power supply unit that outputs a measurement current and a plurality of measurement objects, and the plurality of switch elements are provided. The plurality of switches in the signal switch configured to be able to supply the measurement current by connecting one measurement object selected from the plurality of measurement objects to the power supply unit by being turned on / off. A switching control circuit including a processing unit that performs the on / off control for an element, and includes a detection unit that detects an applied voltage applied to the signal switch from the power supply unit, and the processing unit includes: Comparing the voltage value of the applied voltage detected by the detection unit after the control for stopping the output of the measurement current is performed on the power supply unit with a predetermined voltage threshold value, Concerned When the voltage value of the applied voltage is detected to be equal to or less than the voltage threshold, performing the on-off control for the plurality of switching elements.

  According to a third aspect of the present invention, there is provided a measuring apparatus that measures the voltage generated in the switching control circuit according to the first or second aspect, the power supply unit that outputs the measurement current, the signal switch, and the one measurement object. A voltage measuring unit configured to perform the on / off control on the plurality of switch elements constituting the signal switcher, and select one measurement target among the plurality of measurement targets. The measurement current is supplied by connecting to the power supply unit, and the voltage value of the voltage generated in the one measurement object measured by the voltage measurement unit in the supply state of the measurement current and the measurement current Based on the current value, the resistance of the one measurement object is measured.

  The switching control circuit according to claim 1 and the measurement apparatus according to claim 3, wherein the processing unit is for measurement detected by the detection unit after the control for stopping the output of the measurement current is performed on the power supply unit. When the current value is compared with the current threshold and it is detected that the current value is lower than the current threshold, ON / OFF control is performed for multiple switch elements that constitute the signal switcher. To do.

  Therefore, according to this switching control circuit and this measuring device, for each measurement object connected to the power supply unit via the signal switcher, the measurement current after stopping the output of the measurement current to the power supply unit On / off control for each switch element that constitutes the signal switch while reliably preventing the occurrence of hot switching of each switch element that constitutes the signal switcher in situations where the degree of current decrease varies Can be executed in a shorter time.

  In the switching control circuit according to claim 2 and the measuring device according to claim 3, the processing unit detects the voltage value of the voltage between the pair of output terminals of the power supply unit, and the voltage value is below the voltage threshold value. When it is detected that it has become, the switching process for the signal switcher is executed. Therefore, also in this switching control circuit and this measuring device, for each measurement object connected to the power supply unit via the signal switch, the voltage drop after the output of the measurement current to the power supply unit is stopped In a situation where the degree of the switching is varied, the on / off control for each switch element constituting the signal switcher is further shortened while surely preventing the occurrence of the hot switching of each switch element constituting the signal switcher. Can be performed in time.

FIG. 2 is a configuration diagram showing a configuration of a measuring apparatus 1 having a switching control circuit 7 that performs on / off control for a signal switch 4. 3 is a timing chart for explaining the operation of a switching control circuit 7; It is a block diagram which shows the structure of 1 A of measuring apparatuses which have the other switching control circuit 7A which performs on / off control with respect to the signal switch 4. FIG.

  Hereinafter, embodiments of a switching control circuit and a measuring apparatus having the switching control circuit will be described with reference to the accompanying drawings.

  First, the configuration of the measuring apparatus 1 will be described. In addition, as an example of the measuring apparatus 1, an ohmmeter that measures the resistance of the measurement target will be described as an example.

  A measuring apparatus 1 shown in FIG. 1 includes a plurality of current supply probes 2, the same number of voltage detection probes 3 as the current supply probes 2, a signal switch 4, a power supply unit 5, a voltage measurement unit 6, a switching control circuit 7, and an output unit 8. And the resistance values Ra, Rb, Rc (as an example in this example, three resistors 11a, 11b, 11c (hereinafter also referred to as “resistor 11” unless otherwise specified)) (Hereinafter, it is also referred to as “resistance value R”.) In this example, as an example, the measuring device 1 is configured to measure each resistance value R by the four-terminal method. The current supply probe 2 and the voltage detection probe 3 are brought into contact with each terminal of each resistor 11.

  The signal switching device 4 includes a plurality of switch elements (in this example, as an example, 12 switch elements 21a, 21b, 21c, 21d, and 22a are configured to measure the resistance value R of the three resistors 11 by a four-terminal method). , 22b, 22c, 22d, 23a, 23b, 23c, 23d). In addition, the signal switching unit 4 includes a measurement circuit side including a power supply unit 5 and a voltage measurement unit 6, and a probe side including a plurality of current supply probes 2 and a plurality of voltage detection probes 3 (that is, current supply probes). 2 and the resistor 11 side as a measuring object with which the voltage detection probe 3 is brought into contact.

  The signal switching device 4 includes a plurality of switching elements 21 a, 21 b, 21 c, 21 d (hereinafter, also referred to as “switching element 21” unless otherwise specified). One resistor 11 a selected from the resistors 11 is connected to the power supply unit 5 and the voltage measurement unit 6 or disconnected from the power supply unit 5 and the voltage measurement unit 6. Further, the signal switching unit 4 is controlled by the switching control circuit 7 so that the on / off states of the switch elements 22a, 22b, 22c, and 22d (hereinafter, also referred to as “switch element 22” unless otherwise specified) are controlled. One selected resistor 11 b of the plurality of resistors 11 is connected to the power supply unit 5 and the voltage measurement unit 6 or disconnected from the power supply unit 5 and the voltage measurement unit 6. Further, the signal switching unit 4 is controlled by the switching control circuit 7 by controlling the on / off state of the switch elements 23a, 23b, 23c, and 23d (hereinafter, also referred to as “switch element 23” unless otherwise specified). One selected resistor 11 c among the plurality of resistors 11 is connected to the power supply unit 5 and the voltage measurement unit 6 or disconnected from the power supply unit 5 and the voltage measurement unit 6. That is, the signal switch 4 performs a switching operation for switching between the current supply probe 2 and the voltage detection probe 3 connected to the measurement circuit side.

  Each switch element 21, 22, 23 has a mechanically movable part and mechanically moves a contact to open / close a signal, current / voltage, a contact relay, mechanically movable Various relays such as a non-contact relay that turns on / off a signal, current, and voltage with a semiconductor element without having a portion, and a hybrid relay that combines the advantages of a contact relay and a wireless point relay are used.

  In this example, the power supply unit 5 is configured by a current source as an example, and is controlled by the switching control circuit 7 to output the measurement current I (DC current in this example) from the pair of output terminals 5a and 5b. Or the output can be stopped. In this case, the power supply unit 5 outputs the measurement current I in a state where the output terminal 5a side is at a higher potential than the output terminal 5b side. The voltage measuring unit 6 measures the voltage value V1 of the voltage V input to the pair of input terminals 6a and 6b, and outputs voltage data Dv indicating the voltage value V1 to the switching control circuit 7.

  As an example, the switching control circuit 7 includes a current detector 31, a detection unit 32, and a processing unit 33. In this switching control circuit 7, a current detector 31 is disposed between the output terminal 5 a of the power supply unit 5 and the signal switch 4 to convert the measurement current I output from the power supply unit 5 into a detection voltage Vi. To do. In this example, as an example, the current detector 31 is configured by a detection resistor. However, the present invention is not limited to this, and a detection circuit having another configuration is used as long as it is a detection circuit that converts current into voltage. You can also

  The detection unit 32 includes, for example, an amplifier and an A / D converter (both are shown), and the amplifier receives the detection voltage Vi and amplifies the detection voltage Vi at a predetermined amplification factor, thereby the A / D converter. The A / D converter converts the voltage amplified by the amplifier into current data Di (data indicating the current value I1 of the measurement current I) and outputs it to the processing unit 33.

  As an example, the processing unit 33 includes a CPU and a memory (both not shown), and executes a switching process, a control process, a measurement process, and an output process. In this case, in the switching process, the processing unit 33 performs on / off control for the switch elements 21, 22, and 23 of the signal switch 4 to thereby detect the current supply probe 2 connected to the measurement circuit side and the voltage detection. The signal switching unit 4 is caused to perform a switching operation for switching the probe 3. In the control process, the processing unit 33 controls the power supply unit 5 to stop outputting / stopping the measurement current I from the power supply unit 5 to the signal switch 4.

  In the measurement process, the processing unit 33 calculates (measures) the current value I1 of the measurement current I based on the current data Di output from the detection unit 32, and also outputs the voltage data output from the voltage measurement unit 6. The voltage value V1 of the voltage V input to the input terminals 6a and 6b is calculated (measured) based on Dv, and the signal switch 4, the current supply probe 2 and the voltage value V1 are calculated based on the calculated current value I1 and voltage value V1. The resistance value R of the resistor 11 connected via the voltage detection probe 3 is calculated.

  The memory stores in advance a current threshold value Ith and a reference current value Iref for comparison with the current value I1 of the measurement current I. In this case, the current threshold Ith is equal to the current threshold value Ith if the current value I1 of the measurement current I is less than or equal to this value. It is a current value that does not adversely affect the switch elements 21, 22, and 23 (it does not become hot switching). Further, the reference current value Iref is a current value with which the resistance value R can be calculated with sufficient accuracy if the current value I1 of the measurement current I is greater than this.

  In the output process, the processing unit 33 outputs the calculated (measured) resistance value R of each resistor 11 to the output unit 8. In this example, as will be described later, the processing unit 33 displays the resistance value R on the screen of the output unit 8.

  The output unit 8 is configured by a display device such as an LCD, for example, and displays the resistance value R output from the processing unit 33 on the screen. The output unit 8 is configured by an external interface circuit instead of the display device, and sends the resistance value R to an external device connected to the circuit via a transmission path, or is connected to an external device connected to the circuit. Of course, the resistance value R may be stored in the memory.

  Next, the switching operation for the signal switch 4 by the switching control circuit 7 will be described together with the operation of the measuring apparatus 1 with reference to the drawings. As shown in FIG. 1, it is assumed that the current supply probe 2 and the voltage detection probe 3 are brought into contact with the terminals of the resistors 11, respectively.

  First, as shown in FIG. 2, the processing unit 33 of the switching control circuit 7 executes control processing for the power supply unit 5 to stop the output of the measurement current I, and then performs switching processing for the signal switch 4. The two switch elements 21 and 23 are brought into contact with the first resistance 11a to be measured by moving each switch element 21 to the ON state and all other switch elements 22 and 23 to the OFF state. The current supply probe 2 and the two voltage detection probes 3 are connected to the power supply unit 5 and the voltage measurement unit 6.

  Subsequently, the processing unit 33 executes control processing for the power supply unit 5 to start output of the measurement current I, and the current value of the measurement current I based on the current data Di output from the detection unit 32. While calculating (measuring) I1, the measurement process is executed during a period in which the calculated current value I1 is equal to or greater than the reference current value Iref, the resistance value Ra is calculated, and the calculated resistance value Ra is made to correspond to the resistor 11a. To store in memory. Thereby, the measurement process about the resistor 11a is completed.

  When the measurement process for the first resistor 11a is completed, the processing unit 33 executes the control process for the power supply unit 5 to stop the output of the measurement current I. In this case, the degree of decrease in the measurement current I is determined by the degree of routing of the current supply probe 2 and the voltage detection probe 3 connected to the power supply unit 5 via the signal switch 4 (the magnitude of the wiring impedance and parasitic capacitance). Depending on the resistance value R of the resistor 11, that is, for each resistor 11 connected to the power supply unit 5 or the voltage measuring unit 6 as a measurement target.

  Therefore, the processing unit 33 calculates the current value I1 of the measurement current I based on the current data Di output from the detection unit 32 immediately after stopping the output of the measurement current I to the power supply unit 5. However, a process of comparing the calculated current value I1 and the current threshold value Ith is executed to detect a timing at which the calculated current value I1 becomes equal to or less than the current threshold value Ith. When the processing unit 33 detects this timing, the processing unit 33 performs a switching process on the signal switch 4 to disconnect the resistor 11a, which has been the measurement target, from the power supply unit 5 and the voltage measurement unit 6, and next to the measurement target. The resistor 11b to be connected is connected to the power supply unit 5 and the voltage measurement unit 6 via the current supply probe 2, the voltage detection probe 3, and the signal switch 4.

  As described above, the switching control circuit 7 detects the current value I1 of the measurement current I that is actually flowing, and when the current value I1 is reliably equal to or lower than the current threshold value Ith, A switching process for the switch 4 is executed. For this reason, in this switching control circuit 7 and the measuring apparatus 1 provided with this switching control circuit 7, the occurrence of a situation in which each switch element 21, 22, 23 constituting the signal switch 4 is hot-switched is surely prevented. It is possible to do.

  For example, as shown in FIG. 2, when the current value I1 drops to the current threshold value Ith (when the time t1 has elapsed from when the output of the measurement current I to the first resistor 11a is stopped), The processing unit 33 detects this timing and executes a switching process for the signal switch 4. In this switching process, the processing unit 33 brings each switch element 22 into the on state and all the other switch elements 21 and 23 into the off state so as to contact the resistor 11a that is initially measured. Instead of the two current supply probes 2 and the two voltage detection probes 3, the two current supply probes 2 and the two voltage detections which are brought into contact with the resistor 11b to be measured second. The probe 3 is connected to the power supply unit 5 and the voltage measurement unit 6.

  Subsequently, the processing unit 33 executes control processing for the power supply unit 5 to start output of the measurement current I, and the current value of the measurement current I based on the current data Di output from the detection unit 32. While calculating (measuring) I1, the measurement process is executed during a period in which the calculated current value I1 is equal to or greater than the reference current value Iref, the resistance value Rb is calculated, and the calculated resistance value Rb is made to correspond to the resistor 11b. To store in memory. Thereby, the measurement process for the resistor 11b is completed.

  When the measurement process for the second resistor 11b is completed, the processing unit 33 executes the control process for the power supply unit 5 and stops the output of the measurement current I. Immediately after this, the processing unit 33 calculates the current value I1 of the measurement current I based on the current data Di output from the detection unit 32, and compares the calculated current value I1 with the current threshold Ith. To detect the timing at which the calculated current value I1 becomes equal to or less than the current threshold Ith. Further, when detecting the timing, the processing unit 33 executes a switching process for the signal switch 4 to disconnect the resistor 11b which is the second measurement target from the power supply unit 5 and the voltage measurement unit 6, and the third The resistance 11 c to be measured (the last in this example) is connected to the power supply unit 5 and the voltage measurement unit 6 via the current supply probe 2, the voltage detection probe 3, and the signal switch 4.

  For example, as shown in FIG. 2, when the current value I1 drops to the current threshold value Ith (when the time t2 elapses from when the output of the measurement current I to the second resistor 11b is stopped). Then, at t2 <t1), the processing unit 33 detects this timing and executes the switching process for the signal switch 4. In this switching process, the processing unit 33 contacts each of the switching elements 23 in the ON state and contacts all the other switching elements 21 and 22 in the OFF state so as to contact the resistor 11b that is the second object to be measured. Instead of the two current supply probes 2 and the two voltage detection probes 3, the two current supply probes 2 and the two voltages that are in contact with the resistor 11c to be measured third The detection probe 3 is connected to the power supply unit 5 and the voltage measurement unit 6.

  Subsequently, the processing unit 33 executes control processing for the power supply unit 5 to start output of the measurement current I, and the current value of the measurement current I based on the current data Di output from the detection unit 32. While calculating (measuring) I1, a measurement process is executed during a period in which the calculated current value I1 is equal to or greater than the reference current value Iref, the resistance value Rc is calculated, and the calculated resistance value Rc is made to correspond to the resistor 11c. To store in memory. Thereby, the measurement process for the resistor 11c is completed.

  When the measurement process for the third resistor 11c is completed, the processing unit 33 executes the control process for the power supply unit 5 and stops the output of the measurement current I. Immediately after this, the processing unit 33 calculates the current value I1 of the measurement current I based on the current data Di output from the detection unit 32, and compares the calculated current value I1 with the current threshold Ith. To detect the timing at which the calculated current value I1 becomes equal to or less than the current threshold Ith. In addition, when detecting the timing, the processing unit 33 performs a switching process on the signal switch 4 to shift all the switch elements 21, 22, and 23 to the off state, thereby causing the resistors 11a, 11b, and 11c to switch to each other. All current supply probes 2 and voltage detection probes 3 that are in contact with each other are disconnected from the power supply unit 5 and the voltage measurement unit 6.

  For example, as shown in FIG. 2, when the current value I1 drops to the current threshold value Ith (when the time t3 elapses from when the output of the measurement current I to the third resistor 11c is stopped). Then, at t2 <t3 <t1), the processing unit 33 detects this timing, executes the switching process for the signal switch 4, and shifts all the switch elements 21, 22, and 23 to the OFF state. All the current supply probes 2 and the voltage detection probes 3 are disconnected from the power supply unit 5 and the voltage measurement unit 6.

  Finally, the processing unit 33 executes output processing to read out the measured resistance values Ra, Rb, and Rc of the resistors 11a, 11b, and 11c from the memory and output them to the output unit 8, Each resistance value R (Ra, Rb, Rc) is displayed on the screen. Thereby, the resistance measurement for all the resistors 11a, 11b, and 11c is completed.

  In the switching control circuit 7 and the measurement apparatus 1 including the switching control circuit 7, the processing unit 33 is detected by the detection unit 32 after the control for stopping the output of the measurement current I is performed on the power supply unit 5. The current value I1 (current value I1 calculated from the current data Di) of the measured current I to be detected is compared with a predetermined current threshold value Ith, and the current value I1 is less than or equal to the current threshold value Ith. On / off control for a plurality of switch elements 21, 22, and 23 constituting the signal switch 4 (control for switching from the off state to the on state, and control for switching from the on state to the off state) Execute.

  Therefore, according to the switching control circuit 7 and the measuring device 1, as described above, the power supply unit 5 and the voltage measuring unit 6 are connected to the power supply unit 5 and the voltage measuring unit 6 via the signal switch 4 for each resistor 11 as a measurement target. In a situation where the degree of decrease in the measurement current I after the output of the measurement current I is stopped with respect to the unit 5 varies, each switch element 21, 22, 23 constituting the signal switch 4 is hot-switched Signal switching device while reliably preventing the occurrence of a situation in which the measurement current I having a current value I1 exceeding the current threshold value Ith is flowing (energized state is switched on / off state) ON / OFF control for each of the switch elements 21, 22, and 23 that constitute 4 can be executed in a shorter time.

  In this case, in the above example, out of the times t1, t2, and t3 when the current value I1 of the measurement current I reaches the current threshold value Ith after the output of the measurement current I to the power supply unit 5 is stopped. Since the longest time is t1, the waiting time until the switching process for the signal switcher 4 is executed after the output of the measurement current I to the power supply unit 5 is stopped is uniform as in the prior art. Even with this configuration of time t1, hot switching can be prevented. However, compared to the time required to measure the resistance values R of all the resistors 11 by adopting this configuration, the processing unit 33 is connected to the power supply unit 5 as in the switching control circuit 7 and the measuring device 1 of this example. Each time the control for stopping the output of the measurement current I is executed, the current value I1 of the measurement current I is compared with the current threshold Ith, and the current value I1 becomes equal to or less than the current threshold Ith. In the configuration in which the switching process for the signal switch 4 is executed when the signal is detected, the waiting time until the on / off control for the switch elements 21, 22, 23 constituting the signal switch 4 is performed is shorter. As a result, the time required to calculate the resistance values R of all the resistors 11 can be sufficiently shortened.

  In the switching control circuit 7, the current detector 31 and the detection unit 32 are connected to the output terminal 5 a on the high potential side (output side of the measurement current I) in the power supply unit 5, thereby connecting the detection unit 32 to the detection unit 32. A preferred configuration is adopted in which the prescribed measurement current I can be supplied to the resistance 11 to be measured via the signal switch 4 without being affected by the leakage current, but the leakage current to the detection unit 32 is extremely low. When the influence of this leakage current is negligible, such as when it is small, a configuration in which the current detector 31 and the detection unit 32 are connected to the output terminal 5b on the low potential side (return side) of the measurement current I in the power supply unit 5 is adopted. You can also.

  In the switching control circuit 7 and the measuring apparatus 1 described above, the current value I1 of the measurement current I output from the power supply unit 5 is detected, and the detected current value I1 is compared with the current threshold value Ith. Thus, the configuration is adopted in which the timing for starting the execution of the switching process is detected for the signal switch 4 after the output of the measurement current I to the power supply unit 5 is stopped. The switch elements 21, 22, and 23 of the signal switch 4 are energized also by detecting the voltage between the pair of output terminals 5a and 5b of the power supply unit 5 after the output of the measurement current I is stopped. It is possible to detect whether or not it is in a state.

  Hereinafter, a switching control circuit 7A adopting a configuration for detecting a voltage Vo (applied voltage applied to the signal switch 4) between the pair of output terminals 5a and 5b of the power supply unit 5 and the switching control circuit 7A are provided. The measuring apparatus 1A will be described with reference to FIG. In addition, about the structure same as the switching control circuit 7 and the measuring apparatus 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  First, the configuration of the measuring apparatus 1A will be described together with the configuration of the switching control circuit 7A.

  As shown in FIG. 3, the measuring apparatus 1A includes a plurality of current supply probes 2, the same number of voltage detection probes 3, current switch 4, power supply unit 5A, voltage measurement unit 6, switching control circuit 7A, An output unit 8 is provided, and is configured to be able to measure resistance values R of a plurality of resistors 11 as measurement objects.

  In this example, the power supply unit 5A is configured by a constant current source as an example, and is controlled by the switching control circuit 7A to output a pair of outputs of a measurement current I (DC current) having a constant current value I1 (known). It is configured to be able to output from the terminals 5a and 5b or to stop the output. As an example, the switching control circuit 7A includes a detection unit 32 and a processing unit 33. In the switching control circuit 7A, the detection unit 32 detects the voltage Vo between the pair of output terminals 5a and 5b of the power supply unit 5A, and outputs the voltage data Do indicating the voltage value Vo1 to the processing unit 33.

  In the memory of the processing unit 33, a voltage threshold Vth and a reference voltage value Vref for comparison with the voltage Vo are stored in advance. In this case, the voltage threshold value Vth is equal to the current value I1 of the measurement current I flowing through each of the switch elements 21, 22, and 23 constituting the signal switch 4 if the voltage Vo is lower than this. Even if the signal switching unit 4 performs the switching operation, the voltage value indicates that the current value does not adversely affect the switch elements 21, 22 and 23 constituting the signal switching unit 4 (it does not become hot switching). It is. In addition, the reference voltage value Vref is a current I for measurement having a current value I1 that can calculate the resistance value R with sufficient accuracy if the voltage value of the voltage Vo is equal to or higher than the reference voltage value Vref. It is a voltage value which shows that it is supplied to.

  Next, the switching operation of the signal switch 4 by the switching control circuit 7A will be described with reference to the drawings together with the operation of the measuring apparatus 1A. As shown in FIG. 3, it is assumed that the current supply probe 2 and the voltage detection probe 3 are in contact with the terminals of the resistors 11, respectively. Further, after the measurement of the resistance value Ra for the resistor 11a is completed, the switching process for the signal switch 4 is executed, and the next resistor 11b is connected to the power supply unit 5A and the voltage measuring unit 6 via the signal switch 4 Only the operation will be described, and the description of other operations will be omitted.

  When the processing unit 33 of the switching control circuit 7A detects that the voltage value Vo1 of the voltage Vo calculated based on the voltage data Do output from the detection unit 32 is equal to or higher than the reference voltage value Vref, The measurement process for the resistor 11a is started, and when the measurement process is completed, the control process for the power supply unit 5A is executed to stop the output of the measurement current I. In this case, the degree of decrease in the measurement current I varies for each resistor 11 connected as a measurement target to the power supply unit 5A or the voltage measurement unit 6 as described above, and thus the voltage detected by the detection unit 32 The voltage value Vo1 of Vo is also different for each resistor 11 connected as a measurement target.

  For this reason, the processing unit 33 executes the calculation of the voltage value Vo1 based on the voltage data Do immediately after the output of the measurement current I to the power supply unit 5A is stopped, and the voltage is calculated as the calculated voltage value Vo1. A process of comparing the threshold value Vth is executed, and the timing at which the calculated voltage value Vo1 becomes equal to or lower than the voltage threshold value Vth is detected. Further, when detecting the timing, the processing unit 33 executes a switching process for the signal switch 4 and sets the resistor 11b to be measured next as the current supply probe 2, the voltage detection probe 3, and the signal switch. 4 to the power supply unit 5A and the voltage measurement unit 6.

  As described above, also in this switching control circuit 7A, the processing unit 33 actually detects the voltage value Vo1 of the voltage Vo between the pair of output terminals 5a and 5b of the power supply unit 5A, and the voltage value Vo1 is surely set to the voltage value. When it is detected that the threshold value Vth has been reached, the switching process for the signal switch 4 is executed. For this reason, also in this switching control circuit 7A and the measuring apparatus 1A provided with this switching control circuit 7A, for each resistor 11 connected as a measurement target to the power supply unit 5A and the voltage measuring unit 6 via the signal switch 4. In addition, in a situation where the degree of decrease in the voltage Vo after the output of the measurement current I to the power supply unit 5A is varied, each switch element 21, 22, 23 constituting the signal switch 4 is hot. The on / off control for each of the switch elements 21, 22, and 23 constituting the signal switch 4 can be executed in a shorter time while reliably preventing the occurrence of switching.

  In the above example, the configuration in which the resistance value R of the resistor 11 is measured by the four-terminal method is adopted. However, the switching control circuits 7 and 7A of the signal switcher have the resistance value R of the resistor 11 by the two-terminal method. Needless to say, the present invention can also be applied to a signal switch adopting a configuration for measuring the current. Further, the switching control circuits 7 and 7A of the signal switching unit described above are not only measuring devices that measure resistance values as physical quantities to be measured, but also signal switching units of measuring apparatuses that measure other physical quantities (inductance, capacitance, etc.). Of course, the present invention can also be applied to the control of the above.

DESCRIPTION OF SYMBOLS 1,1A Measuring apparatus 4 Signal switching device 5, 5A Power supply part 7, 7A Switching control circuit 11a, 11b, 11c Resistance 21, 22, 23 Switch element 32 Detection part 33 Processing part I Current for measurement

Claims (3)

The plurality of switching elements are arranged between a power supply unit that outputs a measurement current and a plurality of measurement objects, and the plurality of switching elements are controlled to be turned on / off, thereby measuring the plurality of measurements. A processing unit that performs the on / off control on the plurality of switch elements in a signal switch configured to connect the selected measurement target of the targets to the power supply unit and to supply the measurement current A switching control circuit comprising:
A detection unit for detecting the measurement current output from the power supply unit to the signal switch;
The processing unit is configured to detect a current value of the measurement current detected by the detection unit after the control for stopping the output of the measurement current is performed on the power supply unit, and a predetermined current threshold value. And a switching control circuit that executes the on / off control for the plurality of switch elements when it is detected that the current value of the measurement current is equal to or less than the current threshold value. The plurality of switching elements are arranged between a power supply unit that outputs a measurement current and a plurality of measurement objects, and the plurality of switching elements are controlled to be turned on / off, thereby measuring the plurality of measurements. A processing unit that performs the on / off control on the plurality of switch elements in a signal switch configured to connect the selected measurement target of the targets to the power supply unit and to supply the measurement current A switching control circuit comprising:
A detection unit for detecting an applied voltage applied to the signal switch from the power supply unit;
The processing unit includes a voltage value of the applied voltage detected by the detection unit after the control for stopping the output of the measurement current is performed on the power supply unit, and a predetermined voltage threshold value. And a switching control circuit that executes the on / off control for the plurality of switch elements when it is detected that the voltage value of the applied voltage is equal to or lower than the voltage threshold. The switching control circuit according to claim 1, the power supply unit that outputs the measurement current, the signal switch, and a voltage measurement unit that measures a voltage generated in the one measurement object,
The processing unit executes the on / off control for the plurality of switch elements constituting the signal switcher, and connects one measurement object selected from the plurality of measurement objects to the power supply unit. While supplying the measurement current, based on the voltage value of the voltage generated in the one measurement object measured by the voltage measurement unit in the supply state of the measurement current and the current value of the measurement current A measuring device for measuring the resistance of the one measuring object.

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