JPH0672784B2 - Light reflection encoder - Google Patents

Description

Description: The present invention relates to a light-reflective encoder, and more particularly to a light-reflective encoder having a single stationary optical fiber consisting of a single optical fiber strand.

Conventionally, the position detecting device, which is generally used and includes electronic components such as a graduation plate and a light emitting element and a light receiving element, is adversely affected by electrical noise, temperature, and humidity, or cannot be accurately measured. Equipment that must avoid fire must have fire protection and explosion proof measures, and signal transmission involves voltage drops or electrical distortion, which causes various drawbacks such as transmission over long distances. Was there.

In order to solve the drawbacks of the conventional position detecting device in which the pulse output is an electric signal, an optical encoder using the pulse output as an optical signal has been proposed.

JP-B-57-52640 discloses a two-phase rectangular wave light emitting source having a phase difference of 90 ° with each other at a frequency ω, a code disk provided with slits for passing two light beams from the light emitting source,
A first optical fiber having two tips for receiving two light beams from the light emitting source before they pass through the slit, fixedly arranged parallel to the code disc. And a second optical fiber having two tips for receiving the two light beams that have passed through the phase slit, and directs the light beam from the light emitting source to the code disc. Object which is coupled to the code disc by receiving the light beams before and after passing through the code disc and the phase plate at the tips of the two optical fibers and comparing their light amounts. An optical encoder is disclosed for detecting the movement of the.

However, in the optical encoder disclosed in Japanese Examined Patent Publication No. 57-52640, it is necessary to dispose optical fibers for receiving the light beam emitted from the light emitting source on either the front side or the back side of the slit disk. Therefore, it is necessary to install a means for mechanically coupling the slit disk and the object to be detected in the vicinity of the slit disk so that the slit disk moves in association with the movement of the object to be detected. Next to
With design difficulties. Further, since the optical encoder disclosed in the above Japanese Patent Publication No. 57-52640 requires means for receiving both the irradiation light and the passing light, the encoder can be downsized and the movement of the detected object can be accurately measured. It's hard to do.

On the other hand, Japanese Laid-Open Patent Publication No. 56-87,818 proposes a light reflection type position detecting device which does not require a means for receiving transmitted light or passing light.

However, the position detecting device disclosed in Japanese Patent Publication No. 56-87,818 has the following drawbacks.

That is, in this measuring apparatus, in order to detect the change in the reflectance of light and precisely detect the position of the object to be detected, for example, a scale plate connected to the object to be detected is equivalent to one scale. It is necessary to project light having a width smaller than the width and detect the reflectance of the light which changes as the scale plate moves. Therefore, if the width of the scale for detecting the position with high accuracy is narrowed, the width of the optical fiber that projects light on the scale is reduced accordingly, or the end of the optical fiber and the moving scale plate are It is necessary to keep the distance strictly and control the light irradiation area to be extremely small.

However, as the width of the optical fiber becomes smaller, it becomes more difficult to transmit an effective amount of light, and precise position detection becomes difficult accordingly. Furthermore, if the width of the scale is made extremely narrow, it becomes difficult or impossible to make all the scales provided on the scale plate the same width, the same shape, and the same reflection characteristic, and it becomes difficult to detect the position accurately.

The object of the present invention is to make a motion that moves relative to the optical fiber from one end of one optical fiber consisting of a single optical fiber strand, through an optical grating fixedly arranged thereto. An object of the present invention is to provide a novel light-reflecting encoder that employs a method of irradiating light on the light-reflecting scale of the body.

Another object of the present invention is to irradiate a plurality of light-reflecting scales provided on the moving body with light from one end of an optical fiber through the optical grating, and to reflect light reflected from the plurality of scales to the optical grating. It is to provide a novel light-reflecting encoder that receives at one end of the optical fiber.

It is a further object of the present invention that at least one optical property defining light, such as reflectance, spectrum, etc., has a certain regularity through an optical grating fixedly arranged with respect to an optical fiber. A novel light-reflecting encoder that generates changing light as reflected light from a moving body and detects the regular change of the reflected light through an optical fiber to detect the movement of a detected object connected to the moving body. To provide.

Still another object of the present invention is to provide a reflective encoder in which a detection error of a change in the motion of an object to be detected caused by a slight difference in width, shape or reflectance of each scale is extremely small. Especially.

Still another object of the present invention is to provide a light reflection encoder in which an optical fiber can be arranged only in the direction opposite to the moving body whose position is to be detected through a scale.

Still another object of the present invention is to provide a light-reflecting encoder capable of detecting not only an extremely precise position that changes with the motion of a moving body but also any fixed position of the motion cycle at once. is there.

Further objects and advantages of the present invention will be apparent from the following description.

According to the present invention, such an object and advantage of the present invention comprises: a single stationary optical fiber consisting of a single optical fiber strand, through which light from a light source, Of the optically transparent scales provided on the fixed optical grating, at least two of the optically transparent scales facing the optical fiber are irradiated, and the optically reflective scales provided on the moving body that moves with the movement of the object to be detected. Among them, the reflected light from the light-reflecting graduation facing the light-transmitting graduation and facing the optical fiber is received by the optical fiber strand irradiated with light as described above, and the received optical signal is It is achieved by providing a light-reflecting encoder, which has a configuration in which a photoelectric conversion device is connected to the optical fiber for converting into an electric signal.

The first important point in the present invention is to respond to the movement of the object to be detected relative to the one end of the optical fiber through the optical grating fixedly arranged to the one end of the optical fiber as described above. The point is to irradiate the moving body with light. By using a light grating fixedly arranged to one end of the optical fiber, a plurality of light-reflecting scales of the moving body are irradiated with light and the movement of the moving body is detected to detect the movement of the detected body. It is possible to detect the motion and control the motion of the detected object.

In the following, the above-described aspects of the present invention will be mainly described, but in the present invention, one end of the optical fiber and an optical grating fixedly arranged on the one end are connected to the detection target,
The moving body may move in response to the movement of the detected body, and the moving body may be stationary or may be moving differently from the movement of the detected body.

A second important point in the present invention is that the light transmitted through the optical grating is applied to at least a plurality of light-reflecting scales provided in the irradiation area of the moving body.

That is, according to the present invention using the optical grating, it is possible to detect the movement of the moving body even if the plurality of light-reflecting scales of the moving body are irradiated with light as described above. On the other hand, by irradiating a plurality of light-reflecting scales of a moving body with light, the difference in the reflected light from each scale caused by a slight difference in the shape, size, width, etc. of each scale Since the influence on the whole can be made extremely small, even if there is an error in the shape, size, width, etc. of each scale provided on the moving body, it is possible to accurately detect the movement of the detected body. . Further, irradiating a plurality of the light-reflecting scales of the moving body with light makes it possible to increase the amount of light emitted from one end of the optical fiber and accordingly the amount of light reflected from the light-reflecting scales. The motion of the moving body that moves in response to the motion of the detection body can be detected extremely accurately.

A third important point in the present invention is that the light reflected from the plurality of light-reflecting scales of the moving body is received at the one end of the optical fiber through the light-transmitting scales of the optical grating. That is, since both the emission of the irradiation light toward the moving body and the reception of the reflected light from the moving body are performed through the optical grating at one end of the same optical fiber fixedly arranged with respect to the optical grating,
The direction of the illuminating light and the direction of the reflected light are opposite, but they are the same direction, so just positioning one end of the optical fiber with respect to the light irradiation area of the moving body connected to the object to be detected It becomes possible to effectively use the light for detecting the movement.

Further, since the optical fiber can be arranged only on the side opposite to the detected body of the moving body that moves in response to the change in the movement of the detected body, it is extremely easy to mechanically connect the detected body and the moving body. In addition, downsizing of the device is also advantageous.

According to the present invention, the reflected light from the moving body received at one end of the optical fiber is detected by the photoelectric conversion element connected to the other end.

The reason why the motion of the moving body linked to the object to be detected can be accurately detected by the present invention will be described more specifically with reference to FIGS. 1a, 1b and 2 of the accompanying drawings.

FIGS. 1a and 1b show that the reflected light that is radiated from one end of the optical fiber to the light irradiation area of the moving body through the optical grating and is reflected from the plurality of light reflecting scales again passes through the optical grating. It is shown as a schematic explanatory view of how it is received at the one end.

In FIGS. 1a and 1b, the optical grating 26 has two types of scales having different light transmittances, that is, a scale 28 having light transmission and a scale 28 'having substantially no light transmission and having light reflectivity. To have
On the other hand, the moving body 20 has two kinds of graduations having different light reflectivities, that is, light graduations 24 and graduations 24 'which have substantially no light reflectivity and are preferably light transmissive alternately. . Also, these four scales are advantageously of the same shape, but at least of a shape that allows them to be superimposed.

According to FIG. 1a, the luminous flux emitted from one end 30a of the optical fiber 30 toward the light grating 26 fixedly arranged thereto (the arrow pointing right from 30a in the figure) is the light grating. When it reaches 26, part of it is reflected by the scale 28 '(the arrow pointing left from 26 in the figure) and the other part is the scale of the optical grating 26.
After passing through 28, it reaches a plurality of graduations 24 of the moving body 20 and is reflected (an arrow pointing to the left from 24 in the figure), and again the optical grating 26.
It will be appreciated that through (back) to (received) the one end 30a of the optical fiber 30.

On the other hand, according to FIG. 1b, when the light beam emitted from the one end 30a of the optical fiber 30 toward the optical grating 26 reaches the optical grating 26, a part of the luminous flux 28 'is graduated as in the case of FIG. 1a. This light, which has been reflected by and is also transmitted through the graduation 28 by another part, reaches the plurality of graduations 24 'of the moving body 20 and transmits it (rightward from 20 in the figure). (Arrow) will be understood. Therefore, in the state of FIG. 1b, only a part of the luminous flux emitted from the one end 30a of the optical fiber 30 toward the optical grating 26, that is, the reflected light reflected by the scale 28 'of the optical grating 26 is the one end of the optical fiber. Return to 30a.

One end 30 of the optical fiber 30 in the state of FIGS. 1a and 1b
If the same amount of light is emitted from a, the amount of reflected light received by the one end 30a of the optical fiber in the state of FIG. 1a and the amount of reflected light received by the one end 30a of the optical fiber in the state of FIG. 1b There will be a clear difference.

In the present invention, the optical grating is fixedly arranged with respect to the one end 30a of the optical fiber 30, while the moving body 20 moves relative to the one end 30a of the optical fiber. With the relative movement of the body 20, the relationship between the scale of the optical grating 26 and the scale of the moving body 20 continuously changes from the state shown in FIG. 1a to the state shown in FIG. 1b or vice versa. Then, the amount of reflected light also continuously changes accordingly.

Thus, according to the present invention, for example, the state of FIG.
When the amount of displacement of the moving body with respect to one end of the optical fiber is taken on the horizontal axis and the amount of reflected light is taken on the vertical axis by repeating the continuous change between the states shown in the figure, the result is shown in FIG. As shown, a curve of the amount of reflected light having a constant period is obtained.

Therefore, by detecting the above-mentioned curve of reflected light by the photoelectric conversion element connected to the other end of the optical fiber, the displacement amount of the moving body that moves in response to the change in the movement of the detected body. Therefore, it is possible to accurately detect the change in the motion of the detected object.

In the present invention, as described above, the light is emitted from one end of the optical fiber,
The fixedly arranged light gratings for these are first illuminated. The light grating has graduations with different light transmittances, and does not transmit light over the entire irradiated area that has been irradiated, but only transmits light that passes through the light-transmitting scale in a part of the irradiated area. To do. The scale can be composed of, for example, a scale having a large light transmittance and a scale having a small light transmittance.
The scale having a high light transmittance may be a slit that allows the irradiation light to pass through substantially as it is, or may be the substrate itself of the transparent optical grating. Further, the scale having a small light transmittance can be a scale which substantially absorbs and / or scatters the irradiation light. The scale having a small light transmittance can be formed from, for example, the material of the light grating itself having substantially no light transmittance, or the scale having a small light transmittance can be formed on the surface of the light grating of a material having a large light transmittance. It can be formed of a non-transparent material, such as paint, or by forming the surface of the light grating to scatter and absorb substantially all of the irradiation light, for example by matte finishing. You can also

It is necessary to provide at least one, preferably at least two scales having a large light transmittance in the optical grating, and more preferably a plurality of scales having a large light transmittance (for example, 2 to 100).
And a plurality of scales with a small light transmittance (for example, 2 to 100).
Pieces) are provided alternately. The optical grating is preferably arranged regularly with a large scale of light transmittance and a small scale of small light transmittance, more preferably a scale that transmits light and a scale that does not substantially transmit light alternate. It is arranged regularly. If there are multiple scales on each scale,
The shapes, sizes, widths, and the like of the plurality of scales may be substantially the same or different, but it is preferable that they are substantially the same.

The light transmitted through the optical grating is applied to at least a plurality of light-reflecting scales provided in the irradiation area of the moving body that moves in response to the movement of the detected body, is reflected by the scales, and is re-lighted. It passes through the grating and is received at one end of the optical fiber.

The light-reflecting scale provided on the moving body can be composed of, for example, a scale having different reflectances, for example, a scale having a large light reflectance and a scale having a small light reflectance, or the irradiated light can have different spectra from each other. It can consist of a scale that reflects as reflected light. When the irradiation light is white light, the scales with different reflectances are, for example, the scales with high light reflectance formed by white or silver paint with high brightness and the light formed by light-absorbing black or gray coating. It can be composed of a scale having a small reflectance or a light-transmitting slit provided on a moving body. Further, either one of the scale having a high reflectance and the scale having a low reflectance may be formed from the base body of the moving body itself.

The scale that reflects the irradiated light as reflected light having a spectrum different from each other is, for example, a scale that simply reflects the irradiated light as reflected light having substantially the same spectrum as that of the spectrum, for example, substantially in the wavelength range of the irradiated light. A reflective scale that does not absorb any light, a scale that absorbs only light of a specific wavelength or wavelength range in the irradiated light and reflects light of other wavelengths, for example, only light in the blue wavelength range of white light A scale that absorbs and reflects light in other wavelength ranges or a scale that has a light wavelength conversion capability, such as a scale that receives irradiation of white light and reflects as fluorescence, can be appropriately used. Regarding the reflected light from such a scale, by detecting the intensity of light in the spectrum, for example, a specific wavelength or wavelength range, it is possible to detect the motion of the moving body that moves in response to the motion of the detected body. .

According to the invention, the scale of the light grating and the scale of the moving body are such that the reflected light received at one end of the optical fiber has some regularity with which the movement of the moving body with respect to the one end of the optical fiber can be defined. Have a relationship with. As long as such a relationship is maintained, the numbers of the graduations of the optical grating and the graduations of the moving body, the shape, the size, the width, etc. are arbitrary. For example, the shape of the scale may be a line, a long quadrilateral such as a rectangle, a polygon such as a square or a triangle, or a circle such as a circle or an ellipse, and the size of the scale may be, for example, a short side or a side. It can be polygonal in length on the order of microns to several millimeters, or round in diameter or minor axis on the order of microns to several millimeters. The shape of the scale is preferably linear or rectangular because it can be formed densely.

The relation having the above-mentioned regularity between the scale of the light grating and the scale of the moving body is preferably that the light-transmitting scale or the lattice spacing of the light grating has the light reflection of the moving body moving relative to the light grating. The relationship is such that the light-reflecting scale of the moving body can be overlapped with the light-reflecting scale in the same direction as the moving direction of the characteristic scale, with optical regularity. For example, a light-transmissive linear scale having a short side of a micron and a light non-transmissive (light-reflecting) linear scale having a short side of a micron are arranged alternately with the long side as a boundary. The relationship between a linear or rectangular graduation with a short side of a micron and a linear or rectangular graduation with a short side of a micron, which are alternately arranged with the long side as a boundary, is typical. This is a typical example. Another example is a light grating with the same scale as above, but the scale of the moving body is a light-reflective rectangular scale with a short side of 2a micron and a light-transmissive rectangular scale with a short side of a micron with the long side as a boundary. You may line up alternately.

Alternatively, the scale of the light grating has a light-transmissive rectangular scale with a short side of a micron, a light non-transmissive (light-reflective) rectangular scale with a short side of b micron, a light-transmissive rectangular scale with a short side of c micron, and a short side d. Micron light non-transmissive (light-reflecting) rectangular scales are arranged in this order with the long side as a boundary, while the scale of the moving body is such that the same four scales are adjacent to each other in the above order. It may be on a scale that is open.

In the present invention, the light transmitted through the optical grating is applied to the moving body that moves relative to the optical fiber. Therefore, according to the present invention, one end of the optical fiber is made stationary, and light is applied to at least a plurality of the light-reflecting scales of the moving body from the stationary end through an optical grating fixedly arranged on the one end. Light reflection of a moving body from one end of a moving optical fiber through a light grid fixedly fixed to it, or in motion separate from that of the optical fiber. It is possible to irradiate light on at least a plurality of property scales. In the latter case, when one end of the optical fiber and the moving body move separately, for example, when one end of the optical fiber and the moving body move in opposite directions, and in the same direction at different speeds. Includes cases of exercising. The movement includes all movements having a certain regularity, such as linear movement, curvilinear movement, and rotational movement. The light reflected from the plurality of light-reflecting scales of the moving body is received by one end of the optical fiber through the optical grating and detected by the photoelectric conversion element connected to the other end of the optical fiber. It is as follows.

Therefore, the preferred embodiment of the present invention relates to the movement of the moving body from one end of the optical fiber through at least two graduations having a high light transmittance of the optical grating fixedly arranged with respect to the one end. And irradiate at least two light-reflecting scales of the moving body, and the reflected light from the light-reflecting scales is received at one end of the optical fiber through at least two of the scales of the optical grating, and this received light is received. The reflected light is detected by a photoelectric conversion element connected to the other end of the optical fiber.

By doing so, even if there are minute deviations in the reflection characteristics such as the width, shape, and reflectance of each light-reflecting scale provided on the moving body, a plurality of such deviations are averaged. Since the reflected light can be grasped at one end of the optical fiber, it is possible to detect the position change of the moving body with extremely high accuracy, and thereby to detect the change of the motion of the detected object with high accuracy.

According to the present invention, further objects and advantages described above are as follows: (A) One stationary optical fiber composed of a single optical fiber strand and fixedly arranged with respect to one end of the optical fiber. It has a fixed optical grating and a moving body that is connected to the body to be detected and is movable in response to the movement of the body to be detected. At least a plurality of scales of substantially constant width having different reflectances are provided, and (C) the scale provided on the moving body at least at a part of the position of the fixed optical grating corresponding to the scale of the moving body. Is provided with a scale having a different optical transmissivity, which overlaps optically with regularity, and (D) irradiates a plurality of scales of the moving body with light from a light source through the scale of the fixed optical grating, The one end of the optical fiber that can receive reflected light from the scale of the moving body is fixed The other end of the optical fiber is provided at a position facing the scale of the optical grating, and the other end of the optical fiber is advantageously achieved by a light reflection encoder connected to the photoelectric conversion device.

The encoder of the present invention includes a stationary optical fiber, a first member (optical grating) fixedly arranged with respect to one end of the optical fiber, and a first member movable with respect to the one end of the optical fiber. 2 members (moving body).

The optical fiber is composed of a single optical fiber element having a core and a clad, for example, a step type or a focusing type optical fiber element. Such optical fibers are known per se and are commercially available.

The first member may be attached to the one end of the optical fiber, or may be attached separately from the optical fiber, as long as the first member is fixedly disposed to the one end of the optical fiber. Good.

The first member can take various forms such as a film, a plate-shaped body or a disc.

Similarly, the second member can also take various forms such as a film, a plate, a disc, a cylinder or a round bar.

An encoder of the present invention having a first member fixedly arranged with respect to one end of an optical fiber and a second member movable with respect to the first member is a fixed body in which the first member is stationary. And the second member is a moving body that is coupled to the detected body and moves in response to the movement of the detected body.

In the above-mentioned encoder of the present invention, it is preferable that the second member moves with regularity, and for example, the second member may be a linear motion, a curvilinear motion or a rotary motion.

Therefore, in the encoder of the present invention, the second member may have a rotational movement, or the second member may have a curved or linear movement.

The second member of the encoder of the present invention is provided with a scale having a different light reflectance on the surface facing the first member, and the first member faces the scale of the second member. Scales with different light transmittances are provided at possible positions. The shapes, sizes, widths, mutual relationships and the like of these scales have already been described in the method of the present invention.

In the encoder of the present invention, one end of the optical fiber is arranged at a position facing the scale of the first member (optical grating). As already mentioned above, one end of the optical fiber allows light from the light source to pass through at least two graduations of the first member, preferably through at least two light transmissive graduations of the second member.
It must be arranged so that it can illuminate the scale and receive the reflected light from at least two light-reflecting scales of the second member.

Next, with reference to FIG. 3a, reference examples that can be referred to when carrying out the present invention will be described, and with reference to FIG. 3b, preferred embodiments of the present invention will be described.

FIG. 3a schematically shows a state in which the one end of the optical fiber is viewed from the fiber axis direction of the optical fiber through an optical grating fixedly arranged to one end of the optical fiber. There is. For example, 22 optical fiber strands A and B are randomly present at one end 30a of the optical fiber. The optical fiber strand A indicates a fiber for emitting light toward an optical grating, and the optical fiber strand B is of a second member (not shown, which is understood to be on the front side of the paper surface). 3 illustrates a fiber for receiving reflected light from a light reflective scale.

Further, the optical grating has, for example, a light transmitting scale 28 and a light reflecting scale 28 '.

In the state shown in FIG. 3a, the light emitted from the optical fiber strand A passes through the optical grid at the plurality of scales 28, while it is reflected by the optical grid at the scale 28 'and received by the optical fiber B. Be taken. The light passing through the scale 28 of the optical grating reaches the second member, and when the light reflecting scale of the second member is located there, it is reflected and again passes through the scale 28 of the optical fiber. If the light-transmissive scale of the second member is received by one end of the optical fiber strand B facing 28, there is no transmission of light there back to the optical fiber.

Therefore, the other ends of the optical fiber strands A are bundled together, the bundle is connected to a light source to send light, while the other end of the optical fiber strands B is similarly bundled into another bundle, If the bundle is connected to a photoelectric conversion element and the reflected light is detected, the reflected light shows a certain regular change along with the movement of the second member (see FIG. 2), which is detected. Thus, the motion of the second member that moves in response to the motion of the detected object is detected,
Therefore, it is possible to detect the motion of the detected object.

FIG. 3b schematically shows the same state as in FIG. 3a when the optical fiber is composed of a single optical fiber strand. In this case as well, light is emitted from one end 30a of the optical fiber,
The light passes through the light-transmissive scale 28 of the optical grating, is reflected at the scale 28 ', and is received at the one end 30a. The light passing through the scale 28 of the light grating is reflected by the light reflecting scale of the second member (not shown) or passes through the light transmitting scale as in the case of FIG. 3a.

Therefore, also in this case, since the reflected light received at the one end 30a of the optical fiber shows a constant regular change with the movement of the second member, the other end of the optical fiber is branched, for example. If one is connected to the light source and the other is connected to the photoelectric conversion element, the motion of the detected object can be detected as in the case of FIG. 3a.

In FIGS. 3a and 3b, as described above, each optical fiber may be a step type or a focusing type, and the one end of the optical fiber may be a substantially flat convex curved surface such as a convex lens. A curved surface such as a curved surface, a convex elliptical shape, or a convex spherical shape may be formed. This convex curved surface is the same curved surface when the liquid makes various convex curved surfaces at the tip of the capillary. Such a convex curved surface can be easily formed by melting one end of the optical fiber. Further, an optical path conversion element such as a lens, a mirror or a prism is interposed between one end of the optical fiber and the first member (optical grating) fixedly arranged with respect to the one end of the optical fiber. Also, the light emitted from one end of the optical fiber reaches the scale of the first member and the scale of the second member through the optical path changing element, and the reflected light from the scale of the second member is It will also be appreciated that the graduation of one member and the light redirecting element are passed again to be received at the one end of the optical fiber.

The present invention also includes the case where such an optical path changing element is interposed.

In the encoder according to the embodiment of the present invention, the scale of the moving body can make a regular movement with respect to the scale provided on the fixed body in response to the movement of the detected body, and The body is preferably a rotating body.

When the moving body is a rotating body, on the surface of the rotating plate facing the fixed body, the reflectance of light is substantially different along the circumference of a virtual circle having the same radial distance from the rotation axis. A rotating body provided with a scale having a constant width is preferably used.

When the moving body is a rotating body, the light is distributed along the circumference of each of at least two virtual circles having different radial distances from the rotation axis on the surface of the rotating plate facing the fixed body. A rotating body provided with a scale having substantially different reflectance, and a weight having an optical regularity with the scale of the rotating plate at least at a part of a position of the fixed body corresponding to the rotating plate. It is possible to use a fixed body provided with at least two scales having different transmittances, which are preferably different from each other.

According to the rotating body and the fixed body as described above, for example, the position of the rotating body is detected by the reflected light from a plurality of scales along the circumference of the first virtual circle of the rotating body, and at the same time, the second or the third body is detected. And the position of the rotating body can be detected by reflected light from a plurality of graduations along the circumference of the other virtual circle, so that the position of the rotating body can be accurately detected, and Thereby, the motion of the object to be detected connected to the rotating body can be accurately detected, and the direction of rotation or the absolute position of the rotating body can be accurately known. It becomes possible to know and control the absolute position of the detected object.

Hereinafter, more specific embodiments of the encoder of the present invention will be described with reference to the accompanying drawings.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 4, 1a and 1b.

FIG. 4 is an explanatory diagram of a reflective encoder according to the first embodiment of the present invention. In the drawing, reference numeral 20 denotes a rotary plate, which is connected to a position detection object (not shown) such as a motor in various devices via a shaft 22 and the like. A large number of light-transmitting scales are arranged on the surface of the rotary plate 20 at approximately the same radial distance from the center of rotation.
24 are provided at the same pitch. In the illustrated example, the scale 24 is formed by a slit, and it is possible to obtain a reflectance different from the reflectance of the surface of the rotating plate 20 by allowing light to pass therethrough. Of course, it is also possible to form by using a material having a reflectance different from that of the surface of the rotary plate 20. In this case, it should be understood that between the scales 24 are light-reflecting scales.

Reference numeral 26 denotes a fixed plate (optical grating) fixedly arranged with respect to the one end 30a of the optical fiber 30. The fixed plate is formed in a circular plate having the same diameter as the rotating plate 20 and is concentric with the rotating plate 20 and is not in contact therewith. Are arranged adjacent to each other. Then, as in the case of the scale 24 of the rotary plate 20, in a part of the circumference of the virtual circle having the same radial distance from the axis, with the same width as the scale 24, and with the same pitch as the pitch between the scales of the rotary plate 20. A plurality of light transmissive scales 28 are provided.
The number of scales 28 is determined in relation to the size of the irradiation area of the light emitted from the optical fiber 30 described later. The scale 28 provided on the fixed plate 26 is also shown as a slit, but as described above, the scale is not limited to the slit as described above. It is of course possible to form a scale. Again, scale 28
Between should be understood as a light reflective scale.
Further, the fixed plate 26 does not have to have the same shape as the rotary plate 20, and may have a size and shape corresponding to a portion irradiated with light, for example.

Reference numeral 30 denotes an optical fiber, one end 30a of which is arranged corresponding to the scale 28 of the fixing plate 26, and the other end 30b of which is connected to the optical signal processing means 32. As described above, the optical fiber 30 may be a single optical fiber or a bundle of a plurality of single optical fibers. The optical fiber 30 irradiates the scale 28 of the fixing plate 26 with the light source in the optical signal processing means 32, and also fixes the fixing plate 26.
The reflected light from the surface such as the above is received and transmitted to the optical signal processing means 32. One end 30a of the optical fiber 30 is processed so that the plurality of scales 28 of the fixing plate 26 are exposed to light according to the thickness of the optical fiber.

The optical signal processing means 32 has a light source (not shown), a photoelectric converter for converting the incident light into an electric signal, and the like, and is well known in the art.

The reflective encoder having such a structure operates as follows. That is, light is emitted from one end 30a of the optical fiber 30 toward the plurality of scales 28 of the fixing plate 26. At this time, if the scale 24 of the rotary plate 20 and the scale 28 of the fixed plate 26 are misaligned (see FIG. 1a), the light emitted from the optical fiber 30 is almost distributed by the surfaces of the rotary plate 20 and the fixed plate 26. It is reflected from the entire illuminated area. After that, when the rotary plate 20 is rotated by half a scale, the scale 24 of the rotary plate 20 and the scale 28 of the fixed plate 26 overlap each other (see FIG. 1b), and the light emitted from the optical fiber 30
The part passes through the scale of the fixed plate 26 and the scale 24 of the rotating plate 20, and only a part of the light irradiated on the surface of the fixed plate 26 is reflected. Furthermore, when the rotary plate 20 rotates by half a scale,
Again, the scale of the rotary plate 20 and the scale 28 of the fixed plate 26 are displaced, and light is reflected from almost the entire light irradiation area. Therefore, when the rotary plate 20 rotates by one scale, the reflectance changes by one cycle, and this change is transmitted through the optical fiber 30 to the optical signal processing means.
This is detected by 32, and it is detected that the detected object has rotated by a predetermined angle.

In the first embodiment described above, one end 30 of the optical fiber 30 is
The a was faced to the stationary plate 26 installed in a stationary state, and the other member, that is, the rotary plate 20 was rotated in response to the motion of the detected object.Instead, it was fixed to one end of the optical fiber 30. The scale of the plate 26 is fixedly connected, and the fixed plate 26 is rotated about its central axis according to the motion of the detected object, and the rotary plate
A member similar to 20 can be installed in a stationary state and function similarly. In this case, the optical signal processing means 32 and the other end 30b of the optical fiber 30 are installed in a stationary state, and one end 30a of the optical fiber 30 is installed.
And the fixed plate 26 can be configured to rotate.

Next, with reference to FIG. 5, a light reflection type encoder, for example, a position detecting device according to a second embodiment of the present invention will be described.

This device comprises an optical fiber 40 placed in a stationary state,
A stationary scale plate 44 which is fixed to one end 42 of the optical fiber 40 and constitutes a first member, a moving scale plate 46 which moves in the longitudinal direction according to the movement of the object to be detected, and the other end 48 of the optical fiber 40. And an optical signal processing means 50 connected to the.

The movable scale plate 46 is formed of a long plate, and as shown in the drawing, a scale 52 of equal pitch formed of a material having different reflectances.
Is equipped with. The moving scale plate 46 is adapted to move in the direction of the arrow, that is, in the longitudinal direction in response to the movement of the object to be detected.

A stationary scale plate 44 is fixed to one end 42 of the optical fiber 40 so as to face the scale 52 of the moving scale plate 46. Therefore, the optical fiber 40, the stationary scale plate 44, and the optical signal processing means 50 are fixedly arranged in a stationary state.

This device according to the second embodiment also operates in the same way as the device according to the first embodiment described above. That is, the moving scale plate 46 is
It moves in the length direction in response to the movement of the object to be detected. Due to this movement, the reflectance of the light emitted from the one end 42 of the optical fiber 40 to the moving scale plate 46 via the stationary scale plate 44 changes. By receiving the reflected light from the one end 42 of the optical fiber 40 and processing the optical signal by the optical signal processing means 50, the position of the object to be detected can be detected.

In the device according to the second embodiment, the moving scale plate 46
Is moved in response to the movement of the object to be detected, but instead of this, the moving scale plate 46 is fixedly arranged in a stationary state, the one end 42 of the optical fiber 40 and the stationary scale plate fixed to this. 44 and 44 can be configured to move in response to the movement of the detected object.

Next, with reference to FIG. 6, a light reflection encoder according to the third embodiment of the present invention will be described.

This device includes an optical fiber 60, a scale member 64 fixedly installed on one end 62 of the optical fiber 60, a rotary scale member 68 connected to a detected object via a shaft 66, and the like. Fiber 60
Optical signal processing means 72 connected to the other end 70 of the.

The rotary scale member 68 is in the shape of a round bar, and as shown in the drawing, has an equal pitch scale formed on the outer peripheral surface thereof with a substance having a different reflectance.
Equipped with 69. As described above, this rotary scale member 68
Is connected to the object to be detected through a shaft 66 and the like, and rotates in response to the motion of the object to be detected.

One end 62 of the optical fiber 60 is fixed to the support plate 74, and the scale member 64 is also fixed to the support plate 74. By this,
The scale member 64 is fixedly installed on one end 62 of the optical fiber 60. The scale member 64 includes a support frame 76 and a film 78 supported by the support frame 76. Vertically striped transparent portions and opaque portions are alternately formed on the film 78, whereby graduations having different transmittances are formed. This scale of the film 78 has the same pitch as the scale 69 of the rotary scale member 68.

The other end 70 of the optical fiber 40 is connected to the optical signal processing means 72 as in the above-mentioned embodiment.

This device according to the third embodiment also has the above-mentioned first and second embodiments.
The position of the detected object can be detected by the operation of the device according to the embodiment of the present invention and the rotation of the rotary scale member 68 in response to the movement of the detected object.

Next, with reference to FIG. 7, a light reflection encoder according to the fourth embodiment of the present invention will be described.

This device includes an optical fiber 80, a first scale member 84 fixedly installed on one end 82 of the optical fiber 80, and a second scale member connected to a detected body through a pinion 86. 88
The optical signal processing means 90, which may have the same structure as that of the above-mentioned embodiment, and the disc-shaped support base 92 for supporting the optical fibers 80 and the like.

The second scale member 88 has a cylindrical shape and is supported so as to be rotatable about the central axis of the disc-shaped support base 92. The upper portion of the inner side surface of the second graduation member 88 is provided with a graduation 94 made of materials having different reflectances. A lower portion of the outer peripheral surface of the second scale member 88 is connected to a gear 96, and the gear 96 transmits the motion of the detected object by a pinion 86.
Meshes with. Thereby, the second scale member 88 is
It will be rotated in response to the motion of the detected object.

The optical fiber 80 and the first scale member are provided on the disc-shaped support base 92.
84 and the optical signal processing means 90 are fixedly installed. As a result, the first scale member 84 has the end 82 of the optical fiber 80.
Is fixedly installed with respect to the second scale member 88.
It is arranged at a position facing the scale 94 of the. Disk support 92
Is arranged so that it can rotate around its central axis. A gear 100 is formed on a lower portion of the outer peripheral surface thereof. The gear 100 meshes with a pinion 98 that rotates in the opposite direction at an angular velocity equal to that of the pinion 86, for example, in response to the motion of the detected object.

In the device according to the fourth specific example described above, the first scale member 84 and the second scale member are responsive to the movement of the object to be detected.
88 rotates in the opposite direction at the same angular velocity. As a result, the position of the detected object can be detected with double accuracy as compared with the case where one is fixed.

It is also possible to rotate the first scale member 84 and rotate the second scale member 88 in the same direction or in the opposite direction at a constant speed or an arbitrary speed in response to the movement of the detected object. it can. By doing so, the position of the detected object with respect to the predetermined moving reference position determined by the rotation speed of the second scale member 88 can be detected.

FIG. 2 is a diagram showing the change in the reflected light amount of light with respect to the rotation of the rotary plate 20 as described above, for example, and the curve A is shown in FIG. 3 in which the optical fiber 30 is provided on the fixed plate 26 side, for example. The change state in the case of another embodiment is shown. In this case, the fixed plate
Even if the flatness of the surface of 26 is bad, the amount of reflected light on the surface of the fixed plate 26 always shows a constant value, so the minimum value is stable,
As a result, the absolute width of the rate of change becomes large, and the change, and thus the change in the position of the object to be detected, can be reliably detected.

On the other hand, the B curve in the figure shows the change state when the optical fiber 30 is arranged on the rotary plate 20 side and light is irradiated. That is, when the optical fiber 30 is arranged on the side of the rotating plate 20 to irradiate and reflect light, the surface of the rotating plate 20 does not have perfect flatness, and one end of the optical fiber and the rotating body Since the distance between and changes, the position and angle of the scale provided on the rotary plate 20 changes, the amount of reflected light changes due to the rotation of the rotary plate 20, and the minimum and maximum values of the reflected light amount are always stable. This means that the absolute width of the change in the amount of reflected light is too small to perform reliable position detection.

Further, the C curve in the figure is a conventional curve in which one scale plate is moved relative to one end of the optical fiber to detect the position without using the scale plate fixedly arranged to one end of the optical fiber. In the reflection type position detection device, a change state of the reflected light amount when light of a size corresponding to a plurality of scale widths is irradiated (see FIG. 9) is shown. In this case, not only the minimum value and the maximum value fluctuate due to the perfectness of the flatness of the surface of the scale plate 11, but also the change in the amount of reflected light is small, which makes it impossible to accurately detect the position of the detected object. near.

In the present invention, the number of graduations of the first member (light grating) that receives irradiation does not substantially affect the rate of change of reflected light. Therefore, in order to obtain a large amount of light, the irradiation area should be increased and the graduation of the second member should be narrowed in order to subdivide the graduation of the second member, and the pitch between the graduations should be narrowed. Etc. are completely free.

As described above, according to the present invention, by receiving the reflected light of at least two light-reflecting scales of the moving body at one end of the optical fiber, the rate of change of the reflected light can be greatly grasped. Moreover, since the minimum value and the maximum value can be kept substantially constant at all times, a change in the motion of the detected object can be detected as a large stable signal, and thus the change in the motion of the detected object can be reliably detected. It becomes possible to detect.

According to the present invention, it is possible to detect the movement of any detected object as long as it can be moved or moved with respect to one end of the optical fiber. Such a movement is detected by converting that movement into movement of the second member (moving body), even if the movement, such as the position, pressure, speed, or volume of the detected body, changes. be able to.

These movements of the body to be detected are transmitted to the movement body by transmitting the change in the movement of the body to be detected to the movement body by any known physical, mechanical or physicochemical means. Can be converted to.

[Brief description of drawings]

FIG. 1a and FIG. 1b are explanatory views showing a state of irradiating a moving body or a second member with light from one end of an optical fiber through an optical grating or a first member and receiving the reflected light according to the present invention. . FIG. 2 is a schematic explanatory view showing the relationship (curve A) between the movement amount of the moving body or the second member by the encoder of the present invention and the change of the reflected light amount at that time. Curve B and curve C
Is by a method or encoder different from the present invention. FIG. 3a is an explanatory diagram of a reference example that can be referred to when carrying out the present invention, and FIG. 3b is an explanatory diagram of a preferred embodiment of the present invention. FIG. 4 is a simplified diagram of a light-reflecting encoder according to the first embodiment of the present invention. FIG. 5 is a simplified diagram of a light reflection encoder according to a second embodiment of the present invention. FIG. 6 is a simplified diagram of a light reflection encoder according to a third embodiment of the present invention. FIG. 7 is a simplified diagram of a light reflection encoder according to the fourth embodiment of the present invention.

Claims (15)

[Claims] 1. An optical transmissive device comprising a single stationary optical fiber made of a single optical fiber strand, through which the light from a light source is provided in a fixed optical grating. Among the scales, at least two light-transmitting scales facing the optical fiber are irradiated, and among the light-reflecting scales provided on the moving body that moves with the movement of the detection object, face the light-transmitting scales. Further, the reflected light from the light-reflecting scale facing the optical fiber is received by the optical fiber element wire irradiated with the light as described above, and the optical fiber is used for converting the received optical signal into an electric signal. A light reflection type encoder having a configuration in which a photoelectric conversion device is connected to. 2. The encoder according to claim 1, wherein the moving body is a rotating body. 3. The encoder according to claim 1, wherein the moving body is a film or a plate-like body. 4. The encoder according to claim 1, wherein the moving body is a cylinder or a round bar. 5. The first invention according to claim 1, wherein the moving body is a disk.
Alternatively, the encoder according to item 2. 6. The encoder according to any one of claims 1 to 5, wherein the fixed optical grating is provided on a film, a plate-shaped body or a disk. 7. The encoder according to claim 1, wherein the fixed optical grating is attached to one end of the optical fiber facing the moving body. 8. The encoder according to any one of claims 1 to 7, wherein the moving body makes a rotational movement. 9. The encoder according to any one of claims 1 to 7, wherein the moving body makes a curved or linear movement. 10. (A) One stationary optical fiber made of a single optical fiber element, a fixed optical grating fixedly arranged with respect to one end of the optical fiber, and an object to be detected. And a moving body that is movable in response to the movement of the object to be detected. (B) The surface of the moving body facing the fixed body has a substantially constant width with different light reflectance. At least a plurality of graduations are provided, and (C) at least part of the position corresponding to the graduation of the moving body of the fixed optical grating has optical regularity with the graduation provided on the moving body. Scales having overlapping different light transmittances are provided, and (D) light from a light source is applied to a plurality of scales of the moving body through the scales of the fixed optical grating, and the scales of the moving body are provided. The one end of the optical fiber capable of receiving reflected light from the optical fiber is provided at a position facing the scale of the fixed optical grating. Cage, light reflection type encoder according to paragraph 1 claims to which the other end of the optical fiber is connected to the photoelectric conversion device, it is characterized. 11. The scale according to claim 10, wherein the scale of the moving body makes a regular movement with respect to the scale provided on the fixed optical grating in response to the movement of the detected body. encoder. 12. A movable body is a rotating plate.
The encoder according to item 10. 13. The moving body is a rotating plate, and the light reflectance is on the surface of the rotating plate facing the fixed optical grating along the circumference of an imaginary circle having the same radial distance from the rotation axis. The encoder according to claim 10, wherein different scales having a substantially constant width are provided. 14. Reflection of light along the circumference of each of at least two virtual circles having different radial distances from the axis of rotation on a surface of a rotating plate forming a moving body facing the fixed optical grating. Scales having substantially different rates are provided, and at least a part of the position of the fixed optical grating corresponding to the rotating plate is provided on each circumference of at least two virtual circles of the rotating plate. The encoder according to any one of claims 10 to 13, further comprising a graduation that is provided along the graduation and that has an optical regularity and that has a different transmittance. 15. A light-reflecting scale having a width substantially equal to or greater than the width of a light-transmitting scale provided on the fixed optical grating is provided on a surface of the rotary plate facing the fixed optical grating. An encoder according to any one of claims 10 to 14, wherein the encoder is provided.