JPS5813681Y2 - Micrometer with spindle rotation angle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a micrometer having a spindle rotation angle detector, and more particularly to a micrometer having a detector for electrically detecting the spindle rotation angle.

A micrometer that electrically detects the spindle rotation angle, that is, the amount of length measurement movement of the micrometer and displays it digitally is well known, and has great utility as a highly accurate micrometer with little reading error.

A conventional spindle rotation angle detector in a micrometer has a slit plate with a plurality of slits fixed to the spindle, and a photoelectric conversion device consisting of a light emitting/receiving device and a reference index plate having slits similar to the slit plate inside the sleeve. The rotation angle of the spindle was detected as an electrical signal by photoelectric conversion using a slit plate, a reference index plate, and a photoelectric converter.

In this conventional device, the photoelectric converter must be installed on the side of the slit plate, and for this purpose, the slit plate must be set larger than the diameter of the spindle.
A drawback of the conventional device is that the diameter of the sleeve is significantly large.

Furthermore, the increased sleeve diameter makes it difficult to perform measurements with the micrometer, and the weight of the micrometer itself increases.

Furthermore, in conventional devices, the slit plate or reference index plate requires complicated processing such as creating multiple slits on a glass plate or cutting fine slits in a thin metal plate, and the light emitting device of the photoelectric converter is subject to vibrations. There are drawbacks such as the fact that the light emitting function is easily disabled due to disconnection due to wire breakage or adhesion of dust, and the micrometer also has the drawback that it is necessary to disassemble the micrometer for repair in the event of a malfunction.

The present invention was devised in view of the above-mentioned conventional problems, and its purpose is to provide a microcontroller with an improved spindle rotation angle detector that can electrically detect the spindle rotation angle with a very simple structure and with high precision. The aim is to provide meters.

In order to achieve the above object, the present invention fixes to the spindle a rotating electrode having a spline shape with external teeth formed on the outer periphery and having a length at least equal to the effective movement length of the spindle in the axial direction of the spindle. A substantially ring-shaped stationary electrode with inner teeth facing the outer teeth of the rotating electrode across a gap is fixed inside the sleeve, and the capacitance value between the two electrodes is determined by the relative movement of the two electrodes based on the rotation of the spindle. It is characterized by electrically detecting the rotation angle of the spindle based on the change in rotation angle.

According to the present invention, the rotating electrode can be formed to have the same diameter as the spindle or can be disposed in place of a part of the conventional spindle, and the fixed electrode can also be formed with a very small diameter close to the rotating electrode. It can be formed from a substantially annular electrode consisting of a micrometer, and can be constructed with almost the same size as a normal mechanical micrometer.

A gear-shaped electrode surface is formed on the rotating and fixed electrodes, and the capacitance value between the electrodes changes due to the relative movement of both external teeth and internal teeth, and the detector can detect an electrical signal that approximates a sine wave. can.

By arbitrarily setting the number of gears, a desired number of detection signals for one spindle rotation can be obtained, and a highly accurate micrometer can be obtained.

A high-frequency signal is supplied from the outside to the detector consisting of both electrodes, and the change in capacitance between the electrodes can be detected as an electrical signal, and this detection signal is digitally displayed on an external display. .

In the present invention, any means other than applying a high frequency signal can be used as the means for extracting the capacitance value, and the display of the detection signal can also be digital or analog.

According to the present invention, the fixed electrode can also be formed from at least two electrodes, and both fixed electrodes are provided with internal teeth of the same shape, and fixedly arranged at different phases in the circumferential direction. Furthermore, a detection signal having a phase difference can be obtained, and by appropriately combining these two signals, it is possible to obtain a minimum scale finer than the number of teeth of the electrode.

In the present invention, the tooth-shaped recess of at least one of the internal teeth of the fixed electrode or the external teeth of the rotating electrode can be filled with a dielectric material such as resin.

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a preferred embodiment of a micrometer having a spindle rotation angle detector according to the present invention.

The basic structure of the micrometer according to the present invention is the same as that of a conventional mechanical micrometer, and includes an anvil 12 fixed to one end of a frame 10 and a spindle 14 movably provided at the other end. The length of the object to be measured is measured by sandwiching the object to be measured between the anvil 12 and the spindle 14.

The spindle 14 is rotatably and axially movably held within a sleeve 16;
A sinful 18 is fixed to cover the outside.

A sleeve stop 20 is screwed to the sleeve 16, and the sleeve stop 20 firmly fixes the sleeve 16 to the frame 10, and one end of the spindle 14 is pivotally supported by the sleeve stop 20.

A fixing screw portion 16a is provided at one end of the sleeve 16,
The rotation edge portion 14a of the spindle 14 is the fixed screw portion 16a.
By meshing with the spindle 14, the spindle 14 can move in its axial direction when the spindle 14 rotates.

At one end of the spindle 14 is a well-known ratchet stop 2.
2 is provided.

What is characteristic about the present invention is that a rotating electrode 24 is fixed to the spindle 14, and fixed electrodes 26 and 28 are arranged opposite to the rotating electrode 24.

In the illustrated embodiment, the rotating electrode 24 is connected to the spindle 1
4, as shown in detail in FIG.
A plurality of external teeth 24a are formed at equal intervals on its outer periphery.

In the illustrated embodiment, the external teeth 24a have a substantially rectangular cross section, and 25 external teeth 24a are arranged at equal intervals around the outer circumference of the rotating electrode 24.

The rotating electrode 24 has a spline shape having a length in the axial direction of the spindle 14 that is at least equal to the effective movement length of the spindle 14 .

On the other hand, in the embodiment, the fixed electrodes consist of a first fixed electrode 26 and a second fixed electrode 28, both of which have the same shape, so the shape of the first fixed electrode 26 will be explained with reference to FIG.

The first fixed electrode 26 has a substantially ring shape, and has internal teeth 26a formed on its inner periphery, and these internal teeth 26a are arranged to face the external teeth 24a of the rotating electrode 24 with a predetermined gap in between. .

That is, the rotating and fixed electrodes 24, 26 are arranged with the same name,
The outer periphery of the rotating electrode 24 has a slightly smaller diameter than the inner periphery of the inner teeth of the fixed electrode 26, and the gap between the two allows the rotating electrode 24 to freely rotate within the fixed electrode 26.

The first fixed electrode 26 is inserted and fixed into an insulating holding cylinder 30 housed in the inner chamber 16b of the sleeve 16.

Then, a ring-shaped insulating spacer 32 and a second electrode 28 are further inserted in order into the insulation holding cylinder 30, a ring-shaped insulation set screw 34 is screwed into the opening of the insulation holding cylinder 30, and the first fixed electrode 26 and the second fixed electrode 28 are positioned and fixed within the sleeve 16 via the insulating holding cylinder 30.

The insulation retaining tube 30 is held fixed within the sleeve 16 when the sleeve stop 20 is screwed onto the sleeve 16.

The second electrode port has the same shape as the first electrode 26, but the third electrode
As shown in the figure, the internal teeth 28a of the second electrode 28 are 1/1/2 of the internal tooth pitch P with respect to the internal teeth 26a of the first electrode 26.
They are fixedly disposed at positions that differ in phase by an angle of deviation equal to 4.

Each inner tooth 26a of the first fixed electrode 26 and the second fixed electrode 28
, 28a have a substantially rectangular cross section like the external teeth 24a of the rotating electrode 24, and 25 of them are arranged at equal intervals.

From the above explanation, it is understood that in the present invention, the rotating electrode 24 and the fixed electrodes 26 and 28 are placed opposite to each other with a gap in between, and by forming both electrodes from a good electrical conductor, both electrodes form a variable capacitance. .

In FIG. 1, the rotating electrode 24 is grounded to the frame 10 via the spindle 14, the sleeve stopper 20, and the sleeve 16, and is electrically connected to the ground terminal of a plug receptacle 36 provided on the frame 10.

Similarly, the first fixed electrode 26 and the second fixed electrode 28 are electrically connected to electrode terminals of the plug receiver 36 via lead wires (not shown).

A plug 38 is removably connected to the plug receiver 36, and is connected to each electrode 24, 26 and 2 through a lead wire 40 of the plug wing.
8 is led to a circuit section connected to the outside of the micrometer.

The embodiment of the present invention has the above configuration, and its operation will be explained below.

As mentioned above, the rotating electrode 24 and the first fixed electrode 26 form a first variable capacitor, and similarly the rotating electrode 24 and the second fixed electrode 26 form a first variable capacitor.
The fixed electrode 28 forms a second variable capacitor.

The capacitance value of each of these capacitors changes as the rotating electrode 24 rotates as the spindle 14 rotates, and the opposing positions of the external teeth and internal teeth change.

The capacitance value change at this time can be arbitrarily selected depending on the shape of the internal teeth and external teeth or the number of each tooth, but it is understood that it becomes a sine wave shape as the spindle 14 rotates.

Therefore, by electrically detecting this capacitance value change, it becomes possible to electrically detect the rotation angle of the spindle 14.

In the illustrated embodiment, the first fixed electrode 26 and the second electrode 28 are fixedly arranged with a pitch deviation of 1/4, so that the capacitance values of the two electrodes change with a phase different by 90 degrees. The rain detection signals are added and subtracted by a 4-division circuit or the like, making it possible to obtain fine measurement accuracy.

An embodiment of the circuit section for electrically detecting the changes in the two capacitance values described above is shown in FIG.

The circuit section includes two signal detection circuits 42 and 44, one detection circuit 42 being connected to a first variable capacitor 46 and the other detection circuit 44 being connected to a second variable capacitor 48.

The first variable capacitor 46 includes the rotating electrode 24 and the first fixed electrode 2.
A variable capacitance consisting of 6 and 6 is equivalently shown.

Similarly, the second variable capacitor 48 equivalently represents a variable capacitor made up of the rotating electrode 24 and the second fixed electrode 28.

Since signal detection circuits 42 and 44 have the same configuration, detection circuit 42 will be described below.

The first variable capacitor 46 forms a part of an oscillation circuit 50, and the oscillation frequency of the oscillation circuit 50 changes in accordance with a change in capacitance value as the spindle 140 rotates.

After the output of the oscillation circuit 50 is amplified by the amplifier 52,
A frequency voltage converter 54 converts the frequency change into a voltage change, and a shaping circuit 56 converts the output into a sinusoidal waveform.

Therefore, from the signal detection circuits 42 and 44, the spindle 1
As the spindle 14 rotates, a sine wave with a phase difference of 90 degrees is obtained, and the output wave is 2 times per rotation of the spindle 14.
It is understood that there will be five waveforms.

Both waveforms are supplied to a well-known signal division circuit 58 and converted into a desired digital signal, and then a digital count value is displayed on a display 60, and the rotation angle, that is, the amount of axial movement of the spindle 14 is displayed as a measured value. be done.

The signal dividing circuit 58 is composed of, for example, a 4-dividing circuit, and generates 25×4=100 pulses per spindle rotation. At this time, the spindle advances in the 0.5 mi axis direction, so each pulse counts 0.005 mm. This means doing the following.

As described above, the spindle rotation angle is detected as an electrical signal by the circuit shown in FIG. 4, and the measured value can be displayed digitally.

In the embodiment of FIG. 1, it is also possible to read measurement values from scales provided on the sleeve 16 and the simple 18, similar to conventional mechanical micrometers.

In the illustrated embodiment, each electrode 24, 26 and 2
The tooth type No. 8 has a nearly rectangular cross section,
For example, it can be an involute tooth shape or any other tooth shape.

Further, the tooth-shaped recesses of each electrode 24, 26, 28 can be filled with a dielectric material such as resin, and in this case, an arbitrary dielectric constant, that is, a capacitance value can be selected by selecting the dielectric material.
Further, it is possible to eliminate distortion of the detection signal waveform due to dust adhering to the tooth-shaped recess.

Filling with dielectric material is performed by molding and adhering resin to the tooth mold and then cutting the inner or outer periphery of the tooth mold, making it possible to form a smooth circumferential surface on the inner and outer peripheries of the electrode. .

Further, the circuit for detecting a change in capacitance value is not limited to the embodiment shown in FIG. 4, and various other signal conversion circuits can be used.

As explained above, according to the present invention, the spindle rotation angle detector detects the change in capacitance value accompanying the rotation of the spindle, and at this time, as is well known, the spindle moves in the axial direction. Since the rotating electrode has a spline shape with a length at least equal to the effective movement length of the spindle, stable relative movement and accompanying capacitance change can be achieved by the cooperation between the rotating electrode and the fixed electrode, regardless of spindle movement. can be detected, and
The detector provided within the sleeve may have an extremely simple electrode structure, and its size can be significantly reduced compared to conventional ones.

Therefore, according to the present invention, it is possible to obtain highly accurate electrical detection signals with fewer failures using a small and lightweight micrometer.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway view showing a preferred embodiment of a micrometer having a spindle rotation angle detector according to the present invention, and FIG.
The figure is a cross-sectional view of T in FIG. 1, FIG. 3 is an enlarged cross-sectional view of essential parts showing the toothed portions of the rotating electrode and the first and second fixed electrodes in the embodiment of FIG. 1, and FIG. 4 is a cross-sectional view of the present invention FIG. 2 is a block circuit diagram showing an example of a circuit section suitable for the embodiment of the present invention. 14... Spindle, 16... Sleeve, 24... Rotating electrode, 24a... External tooth, 26... First fixed electrode, 28...
Second fixed electrodes, 26a, 28a...internal teeth.

Claims (3)

[Scope of utility model registration request] (1) A rotating electrode that is fixed to the spindle, has external teeth formed on its outer periphery, and has a spline shape that has a length in the axial direction of the spindle that is at least equal to the effective travel length of the spindle; The rotation angle of the spindle is electrically controlled by the capacitance value change between the two electrodes due to the relative movement of the two electrodes based on the rotation of the spindle. A micrometer with a spindle rotation angle detector that detects the angle of rotation. (2) Utility model registration In the micrometer described in claim (1), the fixed electrode has a first electrode having internal teeth of the same shape.
A micrometer comprising a spindle rotation angle detector consisting of a fixed electrode and a second fixed electrode, the first and second fixed electrodes being fixedly arranged in different phases in the circumferential direction. (3) Utility model registration In the micrometer according to either claim (1) or (2), a spindle in which the tooth-shaped recess of at least one of the external teeth or internal teeth of both electrodes is filled with a dielectric material. Micrometer with rotation angle detector.