JPS61266917A - Encoder - Google Patents

Abstract

PURPOSE:To simplify the whole structure including simplification of the formation of a light transmission slit by forming the light transmission slit in a movable slit plate so that the distance from a reference movement position varies continuously in a moving direction. CONSTITUTION:The curved light transmission slit is punched in the movable slit plate 21 so that the distance from the center P of rotation as the reference movement position varies continuously in a rotating direction with some tendency. Consequently, the need for a fixed slit plate having plural fixed light transmission slits which are required before is eliminated. Further, an optical position detecting element 26 composed of successive photoelectric converting elements is used, so the number of bits required for position detection is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention provides a movable slit plate, a transparent slit formed in the movable slit plate, a light source disposed on one side with the movable slit plate sandwiched therebetween, and The present invention relates to an absolute type encoder including an optical position detection element disposed on the other side.

(Summary of the Invention) The present invention provides a moving reference position of the movable slit plate (in the rotary type, the rotation axis of the movable slit plate; in the case of the linear type, the movement reference position of the movable slit plate; , a certain predetermined straight line), the overall structure can be simplified, including the commercialization of the formation of transparent slits, and the number of required bits can be reduced. This makes it possible to effectively achieve simplification of electrical circuits for signal processing.

(Prior art and its problems) A conventional general absolute encoder is shown in Figs. 6 and 7. Fig. 6 is a plan view of the entire movable slit plate, and Fig. 7 is a longitudinal side view and circuit of the encoder. FIG.

This movable slit plate 1 is used in a rotary encoder, and is made of an opaque plate such as a metal plate or a synthetic resin plate in a circular shape, and has a large number of circles around the rotation axis 2 of the movable slit plate 1. An arc-shaped movable light-transmitting slit 3 is formed in a die by punching or the like. The movable light-transmitting slits 3 are formed on concentric circles centered on the rotation axis 2, and some are short along the rotation direction, while others are formed long and thin along the rotation direction.

The reason for forming such a slit pattern is to create a BCD code using the slit pattern and to detect the absolute rotation angle of the movable slit plate 1.

A fixed slit plate 4 is arranged parallel to and opposite to the movable slit plate 1, and the fixed slit plate 4 has the same number of concentric circles as the movable transparent slits 3 formed in the movable slit plate 1. Fixed pitch transparent slits 5 are formed in a row along the diameter direction of the movable slit plate 1.

The movable slit plate 1 and the fixed slit plate 4 are arranged at locations corresponding to the rows of fixed translucent slits 5 on the fixed slit plate 4.
A light source 6 consisting of a plurality of Lzep (light emitting diodes), etc., and a plurality of light receiving elements 7, such as phototransistors, of the same number as the concentric circles are arranged with the two concentric circles in between.

8 is an amplifier connected to the light receiving element 7; 9 is a comparator connected to the amplifier 8; and 10 is a reference power source consisting of a DC power source 11 and a variable resistor 12.

However, the conventional example having such a configuration has the following problems.

That is, the pattern of the movable light-transmitting slits 3 formed on the movable slit plate 1 is extremely complicated.
The drawing for etching is extremely complicated, and the punching and forming of the movable transparent slit 3 itself is also extremely troublesome.
This is a factor in increasing costs.

Furthermore, since the fixed slit plate 4 in which a plurality of fixed transparent slits 5 are formed is required, the overall structure is complicated.

In addition, in order to increase the resolution of rotation angle detection, it is necessary to use a large number of signal bits, and a complex electrical circuit is required to process each bit of signal into an output signal. There was a problem.

This applies regardless of whether it is a rotary type or a linear type.
This also applies regardless of whether the movable slit plate 1 is made of an opaque material or a transparent material.

In addition, for the purpose of cost reduction etc., the movable slit plate 1
When it is made of an opaque material such as a metal plate or a synthetic resin plate, a movable light-transmitting slit 3 is formed in a die to transmit light. Therefore, the longer the movable transparent slit 3 is, and the more the long movable transparent slit 3 is damaged,
The mechanical strength of the movable slit plate 1 may decrease, and the movable slit plate 1 may be deformed in a wavy manner.

If such a deformation occurs, the light beam reaching the light receiving element 7 from the light source 6 may enter not from the predetermined movable light transmitting slit 3 in the movable slit plate 1 but from the movable light transmitting slit 3 next to it. Therefore, a malfunction occurs in detecting the rotation angle of the movable slit plate 1.

When the movable slit plate is made of a transparent material such as glass, it is formed into a non-cuttable light-transmitting slit by etching a deposited film or the like. In this case, there is no reduction in the mechanical strength of the movable slit plate, but there is a problem of increased cost.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and aims to simplify the overall structure including simplifying the formation of transparent slits in the movable slit plate, and to reduce the number of required bits. , and to effectively achieve the simplification of electric circuits for signal processing.

(Configuration and Effects of the Invention) In order to achieve the above object, the present invention has the following configuration.

That is, the encoder of the present invention includes a movable slit plate, a light-transmitting slit formed in the movable slit plate such that the distance from the movement reference position of the movable slit plate continuously changes along the moving direction; The device includes a light source disposed on one side of the movable slit plate, and an optical position detection element disposed on the other side of the movable slit plate and having continuous photoelectric conversion elements.

The present invention includes not only the rotary type but also the linear type. In the above configuration, the "movement reference position of the movable slit plate" is the rotation axis of the movable slit plate in the case of a rotary type, and a certain predetermined straight line in the case of a linear type. In addition, "a state in which the distance from the movement reference position changes continuously along the movement direction" means that in the case of a rotary type, the transparent slit is formed in a curved shape; , means that the light-transmitting slit is formed in a straight line inclined with respect to the predetermined straight line.

The effects of the above configuration of the present invention are as follows.

Light from the light source passes through a light-transmitting slit whose distance from the moving reference position changes continuously with a certain tendency. This transmitted light is captured by an optical position detection element having a series of photoelectric conversion elements.

When the movable slit plate moves, the relative positional relationship of the light-transmitting slit with respect to the optical position detection element changes accordingly. That is, the position through which the light from the light source passes through the light-transmitting slit changes along the length direction of the light-transmitting slit.

As a result, the incident position of light onto the optical position detection element changes along the length direction of the optical position detection element.

Therefore, a one-to-one correspondence is established between the position of the moving movable slit plate and the light receiving position of the optical position detection element. Therefore, the encoder of the present invention can detect the absolute position of the movable slit plate.

In addition, since the optical position detection element is formed in a state in which the distance from the movement reference position changes continuously with a certain tendency, the fixed slit plate with multiple fixed translucent slits that was required in the past is no longer required. You can also do that.

In addition, since the photoelectric conversion element uses a continuous optical position detection element, the number of bits required for position detection can be reduced, and the conventional example of using light receiving elements such as multiple phototransistors can be reduced. It is possible to eliminate the need for circuit configurations such as amplifiers, comparators, reference power supplies, etc. for each light receiving element, and it is possible to use common parts for one optical position detection element.

From the above, according to the present invention, it is possible to simplify the overall structure including simplifying the formation of transparent slits, reduce the number of required bits, and simplify the electric circuit for signal processing. The effect of being able to do this is demonstrated.

(Description of Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings. 1 to 3 relate to an encoder according to a first embodiment of the present invention, in which FIG. 1 is a perspective view of the encoder, FIG. 2 is a plan view of a movable slit plate, and FIG. 3 is a cross-sectional view and a circuit. FIG.

The movable slit plate 21 is used in a rotary encoder, and is made of an opaque plate such as a metal plate or a synthetic resin plate and has a circular shape. In this case, the movement reference position of the movable slit plate 21 is the axis P of the rotation axis 22 of the movable slit plate 21.

In the movable slit plate 21, a curved transparent slit 23 whose distance from the rotation axis P, which is a movement reference position, changes continuously along the rotation direction with a certain tendency is formed in a die by punching or the like. ing. This light-transmitting slit 23 is formed over 360 degrees.

On one side of the movable slit plate 21, a light source 25 made up of a plurality of light emitting elements 24 such as LEDs is arranged along the diameter direction of the movable slit plate 21.

On the other side of the movable slit plate 21 facing the light source 25, an optical position detection element 26 including a continuous photoelectric conversion element is arranged along the diameter direction of the movable slit plate 21.

The light source 25 and the optical position detection element 26 are each parallel to the movable slit plate 21.

As the optical position detection element 26, a PSD (semiconductor device detection element), a COD (charge coupled device), or the like can be used.

27 is a signal processing circuit connected to the optical position detection element 26. As this signal processing circuit 27, a circuit having a simpler structure than that of the conventional example can be used.

Next, a second embodiment will be described based on FIG. 4.

FIG. 4 is a perspective view of a linear encoder.

In FIG. 4, the same reference numerals as those shown in FIG. 1 according to the first embodiment refer to the same parts as those indicated by the reference numerals in this embodiment.

In this embodiment, the configuration that differs from the first embodiment is as follows.
It is as follows.

The movement reference position of the movable slit plate 21 is a straight line along the linear movement direction of the movable slit plate 21 at a position outside the light-transmitting slit 23 formed in the movable slit plate 21.

When one end edge 21a along the moving direction of the movable slit plate 21 is a straight line, the line through which the one end edge 21a passes may be set as the straight line as the movement reference position.
"The movable transparent slit 23 is formed in a straight line that is inclined at a constant angle with respect to the straight line serving as the movement reference position.

The rest of the configuration is the same as that of the first embodiment, so a description thereof will be omitted.

FIGS. 5A and 5B are plan views of main parts of movable slit plates of other embodiments, respectively.

These problems are caused by the fact that the mechanical strength of the movable slit plate 21 decreases due to the elongated translucent slit 23, and the movable slit plate 21
This is to prevent deformation.

That is, a plurality of reinforcing bridges 28 are provided in the light-transmitting slit 23 at appropriate pitches. This reinforcing bridge 28 is the same body as the movable slit plate 21.

23a is a slit portion in which the elongated light-transmitting slit 23 is divided into a plurality of parts by a reinforcing bridge 28.

By providing the reinforcing bridge 28, the movable slit plate 2
It is possible to prevent a decrease in the intensity of the signal and hence deformation, and to prevent level fluctuations in the output signal.

It should be noted that the present invention also includes embodiments configured as follows.

(i) The movable slit plate 21 is made of a transparent material such as glass.

(ii) The number of transparent slits 23 is two or more.

(iii) A rotary type in which the central angle of the transparent slit 23 is smaller than 360 degrees.

(iv) A rod-shaped light source is used as the light source 25.

[Brief explanation of drawings]

1 to 3 relate to a rotary encoder according to a first embodiment of the present invention, in which FIG. 1 is a perspective view of the encoder, FIG. 2 is a plan view of a movable slit plate, and FIG. 3 is a cross section and circuit. FIG. 4 is a perspective view of the linear encoder according to the second embodiment, and FIGS. 5A and 5B are plan views of the main parts of the movable slit plate of another embodiment. , FIG. 6 is a plan view of a conventional absolute type encoder, and FIG. 7 is a longitudinal sectional side view of the encoder. 21...Movable slit plate, 23...Translucent slit,
25... Light source, 26... Optical position detection element, L...
・Straight line, P...Rotation axis center

Claims (4)

[Claims] (1) A movable slit plate; In this movable slit plate, a transparent slit is formed such that the distance from the movement reference position of the movable slit plate changes continuously along the movement direction; and the movable slit plate. An encoder comprising: a light source disposed on one side of the movable slit plate; and an optical position detection element disposed on the other side of the movable slit plate and having continuous photoelectric conversion elements. (2) The movable slit plate is of a rotary type, the movement reference position of the movable slit plate is the rotation axis of the movable slit plate, and the transparent slit is formed in a curved shape. The encoder described in range item (1). (3) The movable slit plate is of a linear type, and the movement reference position of the movable slit plate is a straight line along the linear movement direction of the movable slit plate at a location outside the light-transmitting slit, and The encoder according to claim 1, wherein the slit is formed in a straight line that is inclined with respect to the straight line that is the movement reference position. (4) The encoder according to claim (1), wherein the optical position detection element is arranged parallel to the movable slit plate.