JPS61107164A - Apparatus for detecting rotary speed - Google Patents

Abstract

PURPOSE:To detect a rotary speed with high accuracy, by arranging two sets of encoding signal detection units in opposed relation to a rotary disc in a state faced to an encoding signal generation part and applying averaging processing to the speed signal value calculated from two encoding signals. CONSTITUTION:One set of two optical sensors 13, 14 form an encoding signal detection unit and provided to the side opposite to a rotary shaft 1. A comparator 15 is provided in order to compare the outputs of the optical sensors 13, 14 and, when angular velocities omega1a, omega1, when the center of a rotary disc 2 is deviated from that of the rotary shaft 1, is calculated on the basis of the outputs of two comparators 9, 15 by averaging processing in an operator 6, a formula is formed and the ripple of a rotary speed becomes small extremely and, as a result, the detection accuracy of the rotary speed can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotational speed detection device that detects the speed of a rotating body such as a Tanabata with high accuracy.

[Conventional technology]

Figure 2 is, for example, Ono Soki■, Catalog CAT, N073.
9-02, is an explanatory diagram of a conventional optical rotational speed detector shown in "Rotary Encoder", etc. In the figure, 1 is a rotating shaft of a rotating body, 2 is a rotating disk fixed to the rotating shaft 1, and 3 Reference numeral 4 indicates a light-transmitting portion serving as a plurality of encode signal generating portions arranged at equal intervals in the circumferential direction with respect to the rotating disk 2; 4 a light-shielding plate disposed opposite to the rotating disk 2 facing the light-transmitting portion 3; 5; is a light-transmitting part provided on the light-shielding plate 4 so as to face the light-transmitting part 3; 6 is a light source such as an LED or lamp arranged on the rotating disk 2; 7.8 is the light-shielding plate 4;
A set of two optical sensors such as photodiodes, which are installed below the light transmitting section 3.5 and receive the original pulses passing through the transparent section 3.5, constitute an encode signal detection unit. Reference numeral 9 is a comparator that compares the outputs of the respective sensor sensors, and 10 is an arithmetic unit that calculates the rotating body speed based on the output of the comparator 9, clock pulses, and other control signals.

Next, the operation will be explained. FIG. 3 is a signal waveform diagram of each part of the circuit within the arithmetic unit to explain this operation. First, a differential pulse b is obtained from the rising edge of the output pulse a, which is the output of the comparator 9 obtained by the original sensor 7.8, and the number of clock pulses C between the differential pulses 5 is counted and integrated. to obtain a sawtooth pulse d. Further, this pulse d is averaged over time to obtain an average value pulse e. The arithmetic processing of each pulse is executed by the arithmetic unit 10, and the minute angular rotation of the rotating disk 2 can be detected as an instantaneous speed. By the way, in order to improve speed detection accuracy,
It is necessary to increase the resolution of the above-mentioned light-transmitting part 3, and today, the light-transmitting part 5,
A type with a light shielding part is used. Note that the transparent parts 5 are provided at equal intervals around the center O of the rotating shaft 1 as shown in FIG. However,
The speed error is corrected by signal processing using an appropriate filter.

[Problem that the invention seeks to solve]

Since the conventional rotational speed detection device is configured as described above, the rotational speed can be detected almost satisfactorily under high resolution conditions with a large number of transparent parts 5. During assembly, rotation detection errors cannot be avoided due to deviations in these assembly positions and deviations (eccentricity) between the rotation centers of the rotating disk 2 and the rotating shaft 1. To explain this with reference to FIG. 5, first, the center of the rotating disk 2 is set at 01
, the actual rotation center is 02, the distance from this center 02 to the light passing point (point on the light passing trajectory) C2 is 1'L, 01
C
Assuming 2t, the rotational speed to be detected is proportional to the number of times of light transmission and light blocking at the light passing point C2. The difference in the number of repetitions of this transparent hole and light blocking is the original light passing point C1 centered at 01.
Since they are equally spaced on the top, the center 01 and the light passing point C
It is expressed by the change in the angle θ of the line connecting 2, that is, the angular velocity ωl. Therefore, when the angle θ is determined with C2 constant, the following is obtained. Here, by differentiating equation (1) and finding ω, we get the following. From this equation (2), C1(t) has a maximum value of L-C2 and a minimum value of jL-.

fl+f As a result, portions where the angular velocity is maximum and minimum occur during the rotation of the rotation di 12201, and this change is included in the rotation detection signal as a low frequency ripple. but,
It is difficult to remove such low frequency ripples with a filter, and there is a problem that this low frequency ripple cannot be avoided without adversely affecting the rotational speed.

This invention was made to solve the above-mentioned problems. Two sets of encoded signals are obtained from a rotating disk having an encoded signal generator, and these encoded signals are averaged to eliminate ripples. The rotation speed detection device according to the present invention has a rotation speed that can minimize speed detection errors by obtaining a small speed detection value.
A rotating disk is attached to the rotating shaft of the rotating body, a plurality of encode signal generating units are provided on the rotating disk, two sets of encode signal detection units are provided facing the encode signal generating unit, and the encode signal detection unit of the two sets is installed. The speed signal values obtained from two sets of encoded signals from the unit are averaged by a speed calculator.

[Effect]

The rotational speed detection device according to the present invention extracts two encoded signals from two sets of encoded signal detection units installed opposite each other in an encoded signal generating section provided on a rotating disk, detects a speed signal from the encoded signals, and detects the speed signal. To obtain a speed signal with smaller ripples than K by averaging processing, and to detect the rotation of a rotating disk with high precision even when the rotation center of the rotating shaft and the rotating disk are eccentric.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 11 is a light source placed on the rotating disk 2;
Reference numeral 12 denotes a light-shielding plate disposed facing the light-transmitting portion 3 of the rotating disk 2, and is provided with a light-transmitting portion similar to that provided on the light-shielding plate 4 described above. Reference numerals 13 and 14 designate optical sensors that together constitute an encode signal detection unit, and are provided on the opposite side of the rotating shaft 1. Note that these optical sensors 13
The spacing of .degree. 14 and the distance to the rotating disk 2 are the same as in the optical sensor 7.8. Reference numeral 15 represents a comparator for comparing the outputs of each optical sensor, and 16 represents an arithmetic unit, which performs the later-described calculation based on the outputs of the two comparators 9 and 15.

Components that are the same as those shown in FIG. 2 are denoted by the same reference numerals, and redundant explanation thereof will be omitted.

Next, the operation will be explained. In this embodiment, the operation of the other encoded signal detection unit added to the one shown in FIG. 2 is the same as that described for the signal waveform processing shown in FIG. This is the angular velocity when Therefore, in the computing unit 16, these two angular velocities ω1. By averaging ωl, we find that ω(1)=(ω1(t)+ω1ノ)×7
They are respectively r/B times larger than those at the same position. Since it is normally R)r, the rotational speed ripple becomes extremely small, and the accuracy of rotational speed detection can be increased accordingly. As a result, the rotational speed detection signal averaged based on the outputs of the two sets of encoded signal detection units can be used as a signal for controlling the speed of a rotating body such as Tanabata with high precision.

In the above embodiment, the rotation speed signal is detected optically, but the same effect can be obtained by detecting the rotation speed signal with a magnetic sensor or proximity sensor and digitally processing the signal. can be obtained. In this case, the encode signal generator is made from a trap such as a magnet or dielectric material.

〔Effect of the invention〕

As described above, according to the present invention, two sets of encode signal detection units are installed opposite to the encode signal generating section provided with a rotary disk, and two sets of encode signal detection units are installed opposite to each other, and two sets of encode signal detection units are obtained based on the encode signals from both of these units. Since the speed signal is configured to be averaged, ripples included in the rotational speed signal can be reduced and the rotational speed can be detected with high accuracy. In this way, the rotational speed of the rotating body can be controlled with high precision based on this rotational speed signal.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a rotational speed detection device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a conventional rotational speed detection device, and FIG. 3 is a signal waveform diagram inside an arithmetic unit showing a speed detection method. FIG. 4 is a plan view of the rotating disk, and FIG. 5 is an explanatory diagram for analyzing speed changes when the center of the rotating disk and its center of rotation are deviated from each other. 1 is a rotating shaft, 2 is a rotating disk, 3 is an encode signal generator, 6 is a light source, 7.8 is an original sensor, 11 is a light source, 13
．． 14 is a light sensor, and 16 is a computing unit. Patent Applicant: Mitsubishi Electric Corporation Figure 1 1: Rotation axis 2: Rotary input device 9 3: Ethic code number generation 1 P 6: Sanskrit S pig 7.8: Asahi wo nbu 11: Hikari, source 13.14: 16: S Practical Calculator Training Figure 2 Figure 3 Figure 4 et al Figure 5 Procedural Amendment (Voluntary) Showa 6 Frost 5-I Day

Claims (1)

[Claims] A rotary disk attached to a rotating shaft of a rotary body, a plurality of encode signal generating sections arranged at equal intervals in the circumferential direction on the rotary disk, and a plurality of encode signal generating sections arranged opposite to the rotary disk facing these encode signal generating sections. A rotational speed detection device comprising two sets of encoded signal detection units, and a speed calculator for averaging speed signal values obtained from two encoded signals from the two sets of encoded signal detection units.