JPH0247454Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for photoelectrically measuring angular displacement.

For example, pressure, weight, etc. can be converted into angular displacement via a primary transducer such as a Bourdon tube or lever.
Therefore, by measuring this angular displacement, mechanical quantities such as these pressures can be determined.

The present applicant previously published the patent publication No. 47-48425 "Angular Displacement Measuring Device" as a device for photoelectrically measuring angular displacement.
is proposed.

As shown in FIG.
Pairs of light sources and light receiving elements 80, 81 and 90, 91
are arranged so that the angular displacement is converted into a relative deviation in the circumferential direction on the slit disk between each light source and the light receiving element. In this way, the amount of light reaching the light receiving elements 81, 91 from the light sources 80, 90 is intermittently changed by the rotating slit disk 72, and a periodically changing voltage signal is generated in the light receiving element, which connects both light sources and the light receiving element. The phase difference between the two periodic voltage signals will change in response to the relative shift between the pair of elements. Therefore, by measuring this phase difference, the angular displacement can be determined.

Now, in this type of photoelectric measuring device,
In order to reduce the influence of noise components due to changes in external light, etc., it is necessary to increase the amount of light emitted by the light source as much as possible, and ultimately to increase the S/N ratio. However, there is a trade-off between the size and capacity of the light source and the lifespan of the light source, so it is not possible to increase the amount of light emitted very much. Note that this applies to direct current lighting, and if the light source is a pulsed lighting source, the flashing will be repeated alternately, so the amount of light emitted each time it is lit can be relatively large. . however,
If a pulse lighting light source is used, the voltage generated in the light receiving element facing the light source through the slit disk will also be pulsed. That is, as shown in FIG. 1A, a pulse group is extracted from the light receiving element, in which a pulse output is generated only when light is transmitted when the light source and the light receiving element face the slit, and there is no output when other light is blocked. In the case of the same phase with a phase difference of 0, the output of the other light-receiving elements will also be exactly like B, which is the same as A above, and if a phase difference occurs due to angular displacement, for example, if A is taken as a reference, In case (b), the generation position of the pulse group is delayed as in case (c). In order to find the phase difference between trains A and C of these two pulse groups, it is best to shape one of these pulse groups into a new pulse and then find the phase difference between the shaped pulses. , signal degradation during the shaping process is inevitable.

By the way, using trains A and C of this pulse group,
Expressing the phase difference in terms of the number of pulses, the phase difference is the number of pulses C that are occurring even after the generation of the pulse group A is completed, that is, when comparing both pulse groups, one The number of pulses corresponds to the number of pulses in a state in which only one pulse is generated. Then, in order to find the phase difference, we need to block the passage of the pulse group C while the pulse group A is occurring, and allow the pulse group C to pass while the pulse group A is not present. It will be a good thing.

Based on the above idea, the present invention aims to provide an angular displacement measuring device that can convert angular displacement into a phase difference between two trains of pulse groups and then extract a pulse corresponding to the phase difference. , as shown in FIGS. 2 and 4, a rotatable displacement rotation shaft is provided, and another rotation shaft that is rotated at a constant angular velocity and has the same axis as the displacement rotation shaft is provided, and the rotation shaft has a A slit disk 72 having radial slits provided at equal intervals around the disk and rotating integrally with its rotation axis is attached, and two pairs of light sources and light receiving elements 10, 11 and 20, facing each other with the slits in between, are attached.
21 to that 1 to 10, 11 to the other 1 to 2
0 and 21 are mounted on a rotating body attached to the displacement rotation shaft, and each of the light sources 10 and 20 of the two pairs of light sources and the light receiving element has a rotating period shorter than the rotation period between adjacent slits of the slit disk 72. Each pulse of a pulse signal generator 30 that sends out two pulse lighting control signals a and b that have short periods, the same period, and different widths, and in which a narrow signal is generated while a wide signal is generated. The light receiving elements 11 and 21 of the two pairs of light sources and light receiving elements are individually connected to the lighting control signal sending end.
Inverts the output of the light receiving element 11 facing the light source 10 to which the pulse lighting control signal a with a large pulse width is supplied, and outputs the inverted signal Co(C) and the output do of the other light receiving element 21. (do) and a logic circuit 40 that forms an AND signal e, and the AND signal e sent from the logic circuit 40 is sent to a counter 5.
0, and the relative deviation of the two pairs of light sources and light receiving element with respect to the slit, which is caused by the angular displacement of the displacement rotation axis, is converted into a count value.

Hereinafter, the present invention will be explained in detail based on an example implemented in the "angular deviation measuring device" shown in FIG. 4 above.

In FIG. 2, pairs 10 and 1 of a light source and a light receiving element are shown.
1, 20 and 21 are the same as those with the same numbers in FIG. There is. The pulse signal generator 30 repeatedly generates clock pulses at equal minute time intervals. Clock pulse generator 3
2 and its clock pulse, Figure 3 a, b
have the same period and different widths, such as
It consists of a waveform processing unit 31 that forms two pulse lighting control signals in which a narrow signal b is generated while the wide signal a is generated, and sends the pulse lighting control signals a and b to the light sources 10 and 20, respectively. do. 40 is a logic circuit consisting of an inhibit and gate, in which the output end of the light receiving element 11 facing the light source 10 into which the control signal a with a large pulse width is introduced is connected to its inverting input end; The output end of the light receiving element 21 is connected to the input end of the counter 50 .

In the above system, if the pairs of light sources and light receiving elements 10, 11 and 20, 21 are in phase with respect to the slit, then when the slit disk 72 (see FIG. 4) rotates, Light sources 10, 2
The amount of light emitted from the slit, which changes in accordance with the pulse lighting control signals a and b, is transmitted when facing the slit, and is blocked otherwise. As a result, the light receiving elements 11 and 21 generate pulse-like outputs corresponding to the control signals a and b, respectively, when light is transmitted, and the former is added to the inverting input terminal of the logic circuit 40, as shown in FIG. reversed,
The latter is added as is to the other input end, making it look like do. Therefore, the AND output of co and do is not sent out, and the count value of the counter 50 is zero.

Next, when the light source and light receiving element pairs 20 and 21 are rotated, the two light source and light receiving element pairs 10 and 11 and 2 are rotated.
A relative angular displacement occurs between 0 and 21. Then, when the inverted output co of the light receiving element 11 is taken as a reference, the generation position of the output do of the other light receiving element 21 shifts in accordance with the angular displacement, causing a delay as shown in d. As a result, the output of the logic circuit 40 is ANDed only during the delay time, and becomes e, which is obtained by passing d, and is counted by the counter 50. As described above, the angular displacement is converted into a count value.

Therefore, the lighting control signals for light beams 10 and 20 are:
The period is the same, but the lighting width is different, so
Waveform distortion of both signals co and d due to slight deviations in the lighting timing and photoelectric conversion timing does not affect the formation of the AND output.

As described above, in the present invention, the light source is lit in pulses at the same period but with different widths, and the phase difference between the two pulse groups generated thereby can be directly extracted as pulses. ,
The S/N ratio can be increased, resulting in improved measurement accuracy.

[Brief explanation of the drawing]

Fig. 1 is an output waveform diagram of an angular displacement measuring device using a pulse lighting light source, Fig. 2 is a block diagram showing the mechanical parts and circuits of the embodiment of the present invention, and Fig. 3 shows the various parts of Fig. 2. The output waveform diagram, FIG. 4, is a front view showing a mechanism part of the prior art and also a part of the present invention. 10, 20...Light source, 30...Pulse signal generator, 40...Logic circuit, 50...Counter.

Claims (1)

[Scope of utility model registration request] A rotatable displacement rotation shaft is provided, and another rotation shaft that is rotated at a constant angular velocity is provided in the same axis state as the displacement rotation shaft, and the rotation shaft has radial slits arranged at equal intervals around a disk. A slit disk 72 is provided and rotates integrally with the rotation axis thereof, and two pairs of light sources and light receiving elements 10, 11 and 20, 21 facing each other with the slit sandwiched therebetween are connected one to one.
0 and 11 are fixed, and the other pair 20 and 21 are mounted on a rotating body attached to the displacement rotation shaft, and
Each of the light sources 10 and 20 of the pair of light sources and light receiving element has a rotation period shorter than the rotation period between adjacent slits of the slit disk 72, and has the same period and different widths, and is generating a wide signal. Each of the two pairs of light sources and light receiving elements is separately connected to each pulse lighting control signal sending end of a pulse signal generator 30 that sends out two pulse lighting control signals a and b that generate narrow width signals. The light receiving elements 11 and 21 are connected to the light source 1 to which a pulse lighting control signal a having a large pulse width is supplied.
The output of the light-receiving element 11 facing 0 is inverted and connected to a logic circuit 40 that forms an AND signal e of the inverted signal C ₀ and the output d ₀ of the other light-receiving element 21. A counter 50 counts the AND signal e sent from the
An angular displacement measuring device that converts the relative deviation of the two pairs of light sources and light receiving elements with respect to the slit caused by the angular displacement of the displacement rotation axis into a counted value.