JPH08210804A - Electrical micrometer - Google Patents

Abstract

PURPOSE: To notify a user that the sensitivity adjustment has been changed and to prevent false measurement by providing a switching means for selecting either a voltage signal for detecting the amount of displacement or a reference voltage signal. CONSTITUTION: An AC voltage is applied from an excitation part 30 to the primary coil of a differential transformer 10 and the amount of displacement of an object to be measured is converted to a voltage signal by the transformer 10. The voltage signal is outputted to an operation amplification part (for measurement) 12 and an operation amplification part (for detecting sensitivity change) 14 from output terminals A and B. A voltage signal (VA+VB) becomes an AC voltage with a constant amplitude regardless of the amount of displacement of the object to be measured and a voltage (reference voltage) with a constant amplitude is outputted from an amplification part 14. An input signal switching part (switching means) 16 selects either of voltage signals from amplification parts 12 and 14 based on a control signal from a control part 24 and outputs it to a detection rectification part 18. The control part 24 compares the output value of the amplification part 14 with a value at the time of starting the measurement and shows a warning on a display 28 when there is at least a specific change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric micrometer, and more particularly to an electric micrometer having a function of issuing a warning when the sensitivity changes during measurement.

[0002]

2. Description of the Related Art An electric micrometer is a device for measuring the amount of displacement, and is composed of a detector and a main body (amplification instruction section). The detector is a device that detects the amount of mechanical displacement of the object to be measured as movement of the measuring element, converts it into an electric signal by a built-in differential transformer, and sends it to the main body. On the other hand, the main body is a device that amplifies the electric signal sent from the detector and displays the displacement amount in analog or digital form.

[0003]

By the way, the main body has sensitivity (in the case of a differential transformer, output voltage with respect to displacement).
There is a sensitivity adjustment unit that adjusts the sensitivity in order to correspond to different detectors. The sensitivity of the sensitivity adjusting section should not change during measurement except when the sensitivity is adjusted. For example, if the sensitivity changes during the process of determining the tolerance of a large number of products, the reliability of the tolerance determination will be lost.

However, it is conceivable that the sensitivity may change during measurement due to an erroneous operation of the sensitivity changeover switch, the magnification adjustment volume, etc., or a displacement of the variable resistor due to vibration. This change in sensitivity is naturally found if the sensitivity is calibrated, but in the case of measuring a plurality of measurement objects one after another as described above, depending on the degree of this change in sensitivity,
It is possible to make a measurement without noticing that it has changed.

The present invention has been made in view of such circumstances, and if the sensitivity adjustment changes even during measurement, the user is notified of the change in sensitivity adjustment, and in some cases, the device is prohibited from being erroneously measured. It is an object of the present invention to provide an electric micrometer that prevents

[0006]

In order to achieve the above object, the present invention provides a displacement amount detecting means for converting a mechanical displacement amount of an object to be measured into a voltage signal corresponding to the displacement amount, and a constant voltage signal. And a reference voltage generating means for outputting, and an input signal switching means for selectively inputting one of the voltage signal output from the displacement amount detecting means and the voltage signal output from the reference voltage generating means. And a sensitivity adjusting means for adjusting the voltage signal selectively input by the input signal switching means so as to have a predetermined voltage sensitivity, and a sensitivity adjustment value is set in advance according to the displacement amount detecting means. When the sensitivity adjusting means and the input signal switching means are switched to input the voltage signal from the displacement amount detecting means,
When the display means for displaying the measured value based on the voltage signal output from the sensitivity adjusting means and the input signal switching means are switched to input the voltage signal from the reference voltage generating means, the sensitivity adjusting means A sensitivity change detection means for detecting whether or not the sensitivity adjustment value has changed based on a voltage signal output from the sensor, and a warning that the sensitivity adjustment value has changed based on the detection output of the sensitivity change detection means. And a warning means for doing so.

[0007]

According to the present invention, the displacement amount detecting means converts the mechanical displacement amount of the object to be measured into a voltage signal corresponding to the displacement amount and inputs the voltage signal to one input terminal of the input signal switching means. At the same time, the constant voltage signal generated by the reference voltage generating means is input to the other input terminal of the input signal switching means. The input signal switching means selectively inputs one of these voltage signals, and when the input signal switching means is switched to input the voltage signal from the displacement amount detecting means,
The display means displays the measured value based on the voltage signal output from the sensitivity adjusting means.

On the other hand, when the input signal switching means is switched to input the voltage signal from the reference voltage generating means, the sensitivity change detecting means causes the sensitivity adjusting means to adjust the sensitivity based on the voltage signal output from the sensitivity adjusting means. Detects whether the value has changed. At this time, if it is detected that the sensitivity adjustment value has changed, the warning means warns that the sensitivity adjustment value has changed.

As a result, a change in sensitivity adjustment can be detected even during measurement, and erroneous measurement can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the electric micrometer according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram showing a first embodiment of an electric micrometer according to the present invention.

As shown in the figure, the electric micrometer is
It is composed of a detector composed of the differential transformer 10 and a main body 50. The main body 50 includes an operational amplification unit (for measurement) 12, an operational amplification unit (for sensitivity adjustment change detection) 14, an input signal switching unit 16, a detection rectification unit 18, a sensitivity adjustment unit 20, an A / D conversion unit 22, and a control unit 24. , Operation unit 26, display unit 28, excitation unit 3
0.

At the time of measurement, an AC voltage is applied to the primary coil of the differential transformer 10 from the exciting unit 30, and the displacement amount of the object to be measured is converted into a voltage signal by the differential transformer 10.
Then, this voltage signal is output from the output terminals A and B of the secondary coil of the differential transformer 10 to the operational amplification section (for measurement) of the main body 50.
12 and an operational amplifier 14 (for detecting a sensitivity adjustment change).

[0013] operational amplifying unit (measurement) 12, the difference voltage signal (V _A of the voltage signal V _B output voltage signal V _A output from the output terminal A of the differential transformer 10 from the output terminal B -V _B ) is amplified and output to the input signal switching unit 16. On the other hand, the operational amplification unit (for sensitivity adjustment change detection) 14
The voltage signal (V which is the sum of the voltage signal V _A and the output signal V _B
A + V _B ) is amplified and output to the input signal switching unit 16.
The voltage signal (V _A + V _B) becomes the alternating voltage of constant amplitude irrespective of the displacement of the object to be measured, is output AC voltage of constant amplitude from the operational amplifying unit (sensitivity adjustment change detection) 14 It will be.

The voltage signals output from the operational amplification unit (for measurement) 12 and the operational amplification unit (for sensitivity adjustment change detection) 14 are input to the input signal switching unit 16. Input signal switching unit 16
Selects and inputs either the voltage signal output from the operational amplification unit (for measurement) 12 or the operational amplification unit (for detection of sensitivity adjustment change) 14 based on the control signal input from the control unit 24, and this selection input Only the detected voltage signal is output to the detection rectification unit 18.

That is, when the displacement amount of the object to be measured is measured, the control unit 20 outputs the voltage signal from the operational amplification unit (for measurement) 12 to the detection rectification unit 18 by the input signal switching unit 1.
When a control signal is output to 6 and a change in the sensitivity adjustment of the main body 50 is to be detected, an input signal is output so that the voltage signal from the operational amplification unit (for detecting the sensitivity adjustment change) 14 is output to the detection rectification unit 18. The control signal is output to the switching unit 16.

The voltage signal selectively input by the input signal switching unit 16 and output to the detection rectification unit 18 is rectified by the detection rectification unit 18 and converted into a DC voltage signal corresponding to the amplitude. Then, this voltage signal is output to the sensitivity adjusting unit 20. In the figure, in order to perform synchronous detection, a synchronous signal is input from the excitation unit 20 to the detection rectification unit 18.

The voltage signal input to the sensitivity adjusting section 20 is
The voltage value is converted into a voltage value according to the sensitivity adjustment value of the sensitivity adjustment unit 20 and output to the A / D converter 22. That is, the sensitivity adjustment unit 20 switches to the sensitivity adjusted by the sensitivity changeover switch, the magnification adjustment volume, or the like according to the sensitivity of the differential transformer 10 (output voltage per unit displacement amount), and the detection rectification unit 18 is switched.
The voltage signal output from the A / D converter 22 is output to the A / D converter 22.

The voltage signal input to the A / D converter 22 is converted into a digital signal and output to the controller 24. When the control unit 20 outputs the control signal to the input signal switching unit 16 so as to selectively input the voltage signal from the operational amplification unit (for measurement) 12, the control signal is input from the A / D conversion unit 22. The measurement result is output to the display unit 28 based on the digital signal.

On the other hand, when the control signal is output to the input signal switching section 16 so as to selectively input the voltage signal from the operational amplification section (for detecting the sensitivity adjustment change) 14, it is input from the A / D conversion section 22. The value of the digital signal is compared with the value of the digital signal from the operational amplifier 14 input at the start of the measurement. When the value of the digital signal changes by a predetermined threshold value or more, the display unit 28 displays a warning that the sensitivity of the sensitivity adjusting unit 20 has changed.

Whether or not the operation unit 26 monitors changes in zero point setting, measurement range setting, tolerance determination setting, and sensitivity adjustment,
If the change in sensitivity adjustment is monitored, the measurement conditions such as how often the change in sensitivity adjustment is detected are set. Next, the control unit 24 of the electric micrometer
The operation of will be described. When measuring the amount of displacement of the object to be measured, first the detector consisting of the differential transformer 10 is fixed to the measuring stand, the reference master, which is the reference dimension, is measured to set the zero point, and the tolerance range such as tolerance range is set. Initial settings such as judgment settings, sensitivity adjustment according to the sensitivity of the detector, and range setting of the display range are performed. Also, it is set whether or not to monitor changes in sensitivity adjustment. Here, it is assumed that the change in sensitivity adjustment is set to be monitored, and the time interval for detecting the change in sensitivity adjustment is set to T (step S10).

When the initial setting is completed and the apparatus is ready for measurement, the control section 24 first causes the input signal switching section 16 to selectively input the voltage signal from the operational amplification section (for detecting the sensitivity adjustment change) 14. Output a control signal (step S1
2), a voltage signal (digital signal obtained by A / D conversion) from the operational amplification unit (for detecting sensitivity adjustment change) 14
Is stored inside (step S14). When that ends, the control unit 24 outputs a control signal to the input signal switching unit 16 so as to selectively input the voltage signal from the operational amplification unit (for measurement) 12 (step S16), and starts detection of the displacement amount. Then, the detected displacement amount is displayed on the display unit 28 (step S18).

The control unit 24 controls the time interval T set above.
During this period, when the displacement amount is detected (step S20), the control signal is output to the input signal switching part 16 again so that the voltage signal is selectively input from the operational amplification part (for detecting the sensitivity adjustment change) 14 (step S20). S22), the voltage signal (digital signal obtained by conversion by the A / D conversion unit 22) from the operational amplification unit (for detecting sensitivity adjustment change) 14 is read. Then, the value of this voltage signal is compared with the value of the voltage signal initially stored in step S14 to determine whether or not these values have changed by a critical value (for example, a value of several percent of the value of the voltage signal). It is determined (step S24). if,
When the change is equal to or more than the critical value, the display unit 28 displays a warning that the sensitivity adjustment has changed or generates a warning sound (step S26).

On the other hand, if it has not changed by more than the critical value, the process returns to step S16, and the control signal is output to the input signal switching unit 16 so that the voltage signal is selectively input from the operational amplification unit (for measurement) 12. Displacement measurement is continued. As described above, the processing from step S16 to step S24 is repeated, and the change in the sensitivity adjustment is detected every T time. Then, if a change in the sensitivity adjustment is detected and a warning is issued, the process may return to step S16 to repeat the processing from step S16 to step S24, or force the measurement. It may be ended.

In the above embodiment, the change in the sensitivity adjustment is detected every T time, but the change in the sensitivity adjustment can be detected by the user at any time by using a manual button or the like. Good. Further, in the first embodiment, the voltage signal having a constant amplitude is obtained from the operational amplifier unit (for detecting the sensitivity adjustment change) 14. However, the voltage signal having the constant amplitude is received by the operational amplifier unit (the sensitivity adjustment change detection). It may be obtained from the exciting unit 30 as in the second embodiment shown in FIG. This also makes it possible to detect a change in sensitivity adjustment, as in the first embodiment.

Furthermore, the first and second parts shown in FIGS.
In the embodiment, the voltage signal having a constant amplitude is input to the detection rectifying unit 18 via the input signal switching unit 16 before the detection rectifying unit 18. However, as in the third embodiment shown in FIG. It is also possible to connect the input signal switching unit 16 to the subsequent stage and input a constant DC voltage from the reference voltage generating unit 32 to this. This is because in the first and second embodiments, a constant DC voltage is generated from the voltage signal having a constant amplitude via the detection rectifying unit 18 and is output to the sensitivity adjusting unit 20, but the constant DC voltage is input from the beginning. The output is provided to the sensitivity adjusting unit 20 via the switching unit 16.

Furthermore, although the differential transformer type electric micrometer has been described in the above embodiments, the configurations shown in the second and third embodiments are other types such as an inductance type, a capacitance type and a strain gauge type. It can also be applied to a type of electric micrometer.

[0027]

As described above, according to the electric micrometer of the present invention, at the time of measurement, a voltage signal having a constant amplitude is input to the sensitivity adjustment means for switching to the measurement signal, and the output value is output. By detecting the change in S, the change in the sensitivity adjustment can be detected even during the measurement, and the erroneous measurement can be prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an electric micrometer according to the present invention.

FIG. 2 is a flowchart showing the operation of the electric micrometer shown in FIG.

FIG. 3 is a configuration diagram showing a second embodiment of the electric micrometer according to the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of an electric micrometer according to the present invention.

[Explanation of symbols]

 10 ... Differential transformer 12 ... Operational amplifier (for measurement) 14 ... Operational amplifier (for sensitivity adjustment change detection) 16 ... Input signal switching section 18 ... Detection rectification section 20 ... Sensitivity adjustment section 22 ... A / D conversion section 24 ... Control Part 26 ... Operation part 28 ... Display part 30 ... Excitation part 32 ... Reference voltage generation part 50 ... Main body

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G01R 35/00 E G08B 21/00 Z

Claims (5)

[Claims] 1. A displacement amount detecting means for converting a mechanical displacement amount of an object to be measured into a voltage signal according to the displacement amount, a reference voltage generating means for outputting a constant voltage signal, and the displacement amount detecting means. An input signal switching means for selectively inputting one of the output voltage signal and the voltage signal output from the reference voltage generating means; and a voltage selectively input in the input signal switching means. Sensitivity adjusting means for adjusting a signal to have a predetermined voltage sensitivity, the sensitivity adjusting means having a sensitivity adjustment value set in advance according to the displacement amount detecting means, and the input signal switching means for detecting the displacement amount. Display means for displaying a measured value based on the voltage signal output from the sensitivity adjusting means when the input signal switching means is switched to input the voltage signal from the means, and the input signal switching means outputs the reference voltage. Sensitivity change detection means for detecting whether or not the sensitivity adjustment value has changed based on the voltage signal output from the sensitivity adjustment means when switched to input the voltage signal from the means, and the sensitivity change detection. An electric micrometer comprising: warning means for warning that the sensitivity adjustment value has changed based on the detection output of the means. 2. The displacement amount detecting means is a detecting means using a differential transformer, and the reference voltage generating means is an arithmetic means for adding two output voltages on the secondary coil side of the differential transformer. The electric micrometer according to claim 1, wherein: 3. The electric micrometer according to claim 1, wherein the reference voltage generating means is a voltage source used for driving the displacement amount detecting means. 4. The electric micrometer according to claim 1, wherein the reference voltage generating means is a DC voltage source for generating a constant DC voltage. 5. The input signal switching unit automatically selects the voltage signal output from the displacement amount detecting unit and the voltage signal output from the reference voltage generating unit. Electric micrometer.