JPS5983062A - Apparatus for detecting speed signal - Google Patents

Abstract

PURPOSE:To enable the inexpensive detection of a speed signal, by a method wherein differentiation circuits for respectively differentiating two-phase output signals of a rotary encoder, a circuit for imparting the absolute values of said output signals and the adder thereof are provided and the output signals of the encoder are detected as a speed signal. CONSTITUTION:Two-phase outputs of a rotary encoder are sent to differentiation circuits 7, 8 and changed in the amplitudes thereof in proportion to the rotary number of the encoder as well as converted to digital signals by wave form shaping devices 13, 14. Absolute value circuits 9, 10 take out the absolute values of the output signals of the differentiation circuits 7, 8 and an adder 11 applies the sum of outputs of the absolute value circuits 9, 10 while the outputs of said circuits 9, 10 are reversed by a reversal amplifier 12. FF15 judges the rotary direction of the rotary encoder by the digital signals of the wave form shaping devices 13, 14. An analogue SW16 outputs the output signals of the adder 11 and the reversal amplifier 12 while changing over the same by the output signal of FF15 and the changed-over signals are outputted through a filter 17. An output wave form is changed in the output voltage in proportion to the rotary number of the encoder and a code is different by the rotary direction. As a result, a speed signal can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a speed signal detection device for use in machine tools, industrial robots, and the like.

Conventional configurations and their problems In general, servo systems used to control positioning in industrial robots, etc. require a velocity loop to stabilize the system and improve responsiveness, and are not used as velocity signal detectors. A DC tacho generator (hereinafter abbreviated as tacho generator) etc. must be provided.

In other words, this type of tachosen requires rectifying brushes, requires maintenance and inspection, has a limited lifespan, and is expensive.
The servo system used for positioning control requires two detectors, one for position and one for speed signal detection.

Furthermore, there is a method to obtain a speed signal by converting the output signal of the Lochri encoder, which is a position detector, to /'/V, but in this case, due to the litho pull of the f/v conversion circuit, at fist speed, Stability becomes an issue.

OBJECTS OF THE INVENTION The present invention has been made from this point of view and aims to provide a device for detecting a speed signal that is stable and has good responsiveness, thereby making the tachogenerator unnecessary.

Structure of the Invention In order to achieve the two objectives, the present invention outputs a sine wave waveform with a constant amplitude and a waveform with a small degree of distortion from a sine wave that has a phase difference of 90 degrees electrically from each other. a two-phase rotary encoder, and two differentiating circuits that differentiate the two-phase output signals of the rotary encoder, respectively.
It is equipped with two absolute value circuits that give the absolute values of the output signals of the two differentiating circuits, and an adder that gives the sum of the output signals of the two absolute value circuits, and uses the output signal of the rotary encoder as a speed signal. This is a speed signal detection device that detects speed signals, does not require a conventional tachogenerator, and can be constructed at low cost.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1, 2, and 3.

FIG. 1 shows a two-phase rotary encoder that outputs sine waves with a constant amplitude and electrically having a phase difference of 90 degrees. Fig. 2 shows a circuit that detects a speed signal from the output signal of the two-phase rotary encoder shown in Fig. 1, and Fig. 3 shows a circuit in which the rotation direction of each part in Figs. 3
This is the output waveform in the case of reverse rotation (FIG. 3(b)).

In FIG. 1, 1.2 is a light emitting diode, 3.4 is a phototransistor/dimeter, and there is a circular plate (not shown) with a slit between the light emitting diodes 1, 2 and phototransistors 3, 40. Transistor 3.4 is supplied with sinusoidal signals having a phase difference of 90 degrees. 6.6 is an amplifier that makes the amplitude of the output signal of the port transistor 3.4 constant; the output waveform of the amplifier 5 is AO, and the output waveform of the amplifier 6 is B○.

In FIG. 2, 7 and 8 are differentiating circuits that differentiate the output waveform of the amplifier 5.6. The output waveform of the differentiating circuit 7 is A1. The output waveform of the differentiating circuit 8 is B1, and the amplitude changes in proportion to the number of rotations of the rotary encoder. Absolute value circuits 9 and 10 take out the absolute value of the output signal of the differential circuit 7.8. The output waveform of the absolute value circuit 9 is A2. The output waveform of the absolute value circuit 10 is B2. 11 is an adder that provides the sum of the output signals of the absolute value circuits 9 and 1o, and the output waveform is C.

12 is an inverting amplifier that inverts the output signal of the adder 11;
13 is a waveform shaper that converts the output signals of the five amplifiers into digital signals, and the output waveform is D.

14 is a waveform shaper that converts the output signal of the amplifier 6 into a digital signal, and the output waveform is CK. Reference numeral 16 denotes a D-type flip 70, which determines the rotational direction of the rotary encoder based on the output signals of the waveform shapers 13 and 14. The output waveform of the D-type flip-flop 15 is Q, which is turned on when the rotary encoder rotates in the forward direction, and turned off when the rotary encoder rotates in the reverse direction. 16 is an analog switch, which controls the adder 11 according to the output signal of the D-type flip-flop 15.
and the output signal of the inverting amplifier 12 are switched and output. 1
7 is a filter that removes ripples from the output signal of the analog switch 16, and the output waveform becomes Co. The output voltage changes in proportion to the number of rotations of the rotary encoder, and the sign of the output signal changes depending on the rotation direction. becomes. In this way, the speed signal can be detected.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, in a rotor-operated servo system, the price is reduced by eliminating the need for a tacho generator, and the need for a rectification plan unlike the tacho generator is eliminated, making maintenance easier. There is no longer any need for inspection,
Its industrial potential is great.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a two-phase rotary encoder used in the device of the present invention, Fig. 2 is a circuit diagram of an embodiment of the device of the present invention, and Fig. 3 is a waveform diagram of each part in the same device. be. 1.2... Light emitting diode, 3t4...
・Phototransistor, 5.6...Amplifier, 7,8
... Differential circuit, 9.10 ... Absolute value circuit,
11... Adder, 12... Inverting amplifier,
13.14...Waveform shaper, 16...D
Type flip frog, 16...analog switch,
17...Filter. Name of agent: Patent attorney Toshio Nakao and one other person
Figure 3 (α-n Q O--1-----
------111----(b)

Claims (1)

[Claims] Two differentiating circuits that differentiate two-phase output signals of a rotary encoder, two absolute value circuits that give the absolute values of the output signals of the two differentiating circuits, and two absolute value circuits that provide the absolute values of the output signals of the two differentiating circuits. A speed signal detection device comprising: an adder for giving a sum of output signals of the circuit, and using the output signal of the rotary encoder as a speed signal. (2) The rotation direction is detected by logical processing of the two-phase output signals of the two-phase rotary encoder, and an analog switch is used to connect the output of the adder and the output of the inverting amplifier that receives the output signal of the adder as input. The speed signal detection device according to claim 1, wherein the output signal of the rotary encoder is made into a speed signal by switching, and the sign of the speed signal differs depending on the direction of rotation.