JPH06161430A - Position detecting device - Google Patents

Abstract

PURPOSE:To provide the position detecting device which accurately detect the position of a moving body, moving linearly while rotating, without contact. CONSTITUTION:A gray scale 10 which varies in light transmissivity or light transmission quantity in the length direction is fixed to a plunger 1 and a light emitting element 2 and a light receiving element 3 are arranged opposite each other across the gray scale 10. The light receiving element 3 generates a detection signal corresponding to the quantity of light received through the gray scale 10. Even when the plunger 1 moves linearly while rotating, the light receiving element 1 and light emitting element 2 are positioned opposite each other across the gray scale 10 at all times, so the position of the plunger 1 can accurately be detected without contact.

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a position detecting device for detecting the position of a moving body which moves linearly with rotation in a non-contact manner.

[0002]

2. Description of the Related Art As is well known, when detecting the position or displacement of a moving body, a non-contact detecting method utilizing changes in light, magnetism, electrostatic capacitance, etc. is often used. This type of non-contact detection is also used in, for example, a drive mechanism of an automatic piano, and an example of a position detection device applied to the drive mechanism will be described with reference to FIG.

First, FIG. 2 is a sectional view showing a schematic structure of a drive mechanism provided in an automatic piano. In this figure,
Reference numeral 1 denotes a plunger, the tip of which is connected to a pedal of an automatic piano (not shown). A coil 7 and a fixed yoke 8 are fixed around the plunger 1 by an external member. This plunger 1 has the coil 7
By the magnetic force generated by, the magnetic head is movable up and down in the arrow X direction or the -X direction in the figure.

Reference numeral 9 denotes a bearing, which restricts the horizontal swing of the plunger 1. 5 is a light emitting element 2 and a light receiving element 3
(See FIG. 3) is a photo interrupter that is opposed to each other with a predetermined gap. Reference numeral 6 denotes a gray scale, one end of which is fixed to the end of the plunger 1 and the other end of which is interposed between the light emitting element 2 and the light receiving element 3 of the photo interrupter 5. The gray scale 6 is, for example, a film in which the gray density gradually changes from the top to the bottom, that is, a film in which the light transmittance increases (or decreases) at a predetermined change rate is attached to a transparent base material. It was set up.

Therefore, when the plunger 1 moves up and down according to the magnetic force generated by the coil 7, the gray scale 6 also moves up and down in conjunction with this. The photo interrupter 5 generates a signal according to the amount of light transmission of gray scale interposed between the light emitting element 2 and the light receiving element 3. Therefore, the position of the plunger 1 can be detected in a non-contact manner by using the output signal of the photo interrupter 5 corresponding to this light transmission amount.

[0006]

By the way, in the above-mentioned conventional position detecting device, although the bearing 9 regulates the lateral oscillation of the plunger 1, it cannot regulate the rotational movement of the plunger 1 around its axis. That is, since the bearing 9 has a circular cross section, the plunger 1 may rotate linearly while rotating around the axis. In such a case, since the gray scale 6 also rotates with the rotation of the plunger 1 around the axis, the gray scale 6 may come into contact with the photo interrupter 5.

For example, as shown in FIG. 4, when the gray scale 6 rotates in the direction of the arrow P in the figure as the plunger 1 rotates, it contacts the photo interrupter 5.
In this way, the gray scale 6 is the photo interrupter 5
If it comes into contact with, there is a problem that the normal operation of the plunger 1 is hindered, and the rotation of the gray scale 6 prevents accurate position detection. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a position detection device that can accurately detect the position of a moving body that moves linearly with rotation in a non-contact manner.

[0008]

According to the present invention, in a position detecting device for detecting the position of a moving body which moves linearly in a non-contact manner, a light transmitting material is formed into a long cylindrical shape, and the longitudinal direction thereof is the moving direction. A member fixed to the moving body in conformity with the moving direction of the body, the scale having a light transmittance or the amount of light transmission changing along the longitudinal direction, and a scale provided inside and outside the hollow of the scale. A light emitting portion and a light receiving portion that are arranged to face each other across the scale are provided, and the light receiving portion generates a detection signal according to the amount of light received through the scale.

[0009]

According to the above construction, the long cylindrical scale whose light transmittance or the light transmission amount changes along the longitudinal direction is fixed to the moving body, and the light emitting portion and the light receiving portion are arranged to face each other across the scale. To be done. The light receiving section generates a detection signal according to the amount of light received through this scale. As a result, even if the moving body moves linearly while rotating, the light-receiving unit and the light-emitting unit always face each other with the scale in between, so that the position of the moving body can be accurately detected in a non-contact manner.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of an embodiment according to the present invention. In this figure, the same parts as those shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.
The configuration shown in FIG. 1 is different from the conventional example shown in FIG. 2 in that a thin plate-shaped gray scale 6 is replaced by a cylindrical gray scale 1
I set it to 0.

The gray scale 10 is formed by forming a light-transmitting member such as glass or plastic (polycarbonate, acrylic, etc.) into a cylindrical shape, and its inner peripheral surface is aligned with the moving direction of the plunger 1 described above. Such a gray scale is printed all around. That is, the gray scale conventionally printed on the plate surface is expanded to the inner circumference of the cylinder. The tip of the gray scale 10 is axially fixed by a nut 11 to a stopper 12 provided on the end surface of the plunger 1. The light emitting element 2 and the light receiving element 3 forming the photo interrupter 5 are placed on the inner peripheral surface and the outer peripheral surface of the gray scale 10, respectively, and are opposed to each other with the cylinder wall of the scale 10 interposed.

In such a structure, when the plunger 1 linearly moves while rotating around the axis, the gray scale 10 also linearly moves while rotating around the axis accordingly. Here, since the gray scale interposed between the light emitting element 2 and the light receiving element 3 is formed so as to be uniform with respect to the moving direction of the plunger 1, the gray scale is simply moved without being involved in the rotational movement. Providing a light transmission amount corresponding to the amount. Therefore, the output signal of the photo interrupter 5 is not affected by the rotation around the axis, and the gray scale 10
Therefore, the amount of movement of the plunger 1 in the axial direction can be detected in a non-contact manner.

In the above-described embodiment, the gray scale is formed on the inner peripheral surface of the gray scale 10, but instead of this, the scale may be formed on the outer peripheral surface of the scale 10. Further, the light emitting element 2 and the light receiving element 3 are arranged so as to face each other on the inner surface side and the outer surface side of the scale 10, respectively.
Alternatively, the light emitting element 2 may be provided on the outer surface side.

[0014]

As described above, according to the present invention, the light emitting portion and the light receiving portion are arranged to face each other with the scale whose light transmittance or the light transmitting amount changes along the longitudinal direction, and the light receiving portion and the light receiving portion face each other. Since the detection signal corresponding to the amount of light received through the scale is generated, the position of the moving body that moves linearly with rotation can be accurately detected in a non-contact manner.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention.

FIG. 2 is a diagram for explaining a conventional example.

FIG. 3 is a diagram for explaining a conventional example.

FIG. 4 is a diagram for explaining a conventional example.

[Explanation of symbols]

1 ... Plunger (moving body), 2 ... Light emitting element (light emitting unit),
3 ... Light receiving element (light receiving portion), 10 ... Gray scale (scale).

Claims (1)

[Claims] 1. A position detecting device for detecting the position of a moving body which moves linearly in a non-contact manner, wherein a light-transmitting material is formed in a long cylindrical shape, and its longitudinal direction is made to coincide with the moving direction of the moving body. A member fixed to the moving body, the scale having a light transmittance or a light amount changing along the longitudinal direction, and a scale provided inside and outside the hollow of the scale, and arranged to face each other across the scale. A position detecting device, comprising: a light emitting unit and a light receiving unit, the light receiving unit generating a detection signal according to an amount of light received through the scale.