JPH11183200A - Optical encoder device - Google Patents

Abstract

(57) [Abstract] [Problem] It is possible to detect the movement amount by receiving light even if the scale moves slightly in the direction perpendicular to the scale movement direction, even if the scale or the optical head is slightly inclined. Provided is an optical encoder device for an optical head. SOLUTION: A light source 11, a scale 13 on which periodic position information is recorded by a light scattering portion and a non-scattering portion, and scattered light from the scale accompanying a change in a relative position between the light source and the scale. Receiving means 1 for detecting a change in the intensity of light
5 and a position change detecting means for detecting a change in the relative position of the scale based on the detection result of the light receiving means, instead of detecting the light blocking state and the transmitted light or reflected light receiving state, The light receiving state and the light transmitting state or the light reflecting state are detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical encoder device for detecting a length, a movement amount, and the like based on a change in a position. The present invention relates to an optical encoder device that receives periodically changing light at a light receiving unit and detects a change in position based on a change in the amount of light.

[0002]

2. Description of the Related Art Conventionally, various length measuring devices, measuring devices,
2. Description of the Related Art In the field of devices such as machine tools and copiers, there are known optical encoder devices capable of detecting a length or a movement by a change in position. Hereinafter, a transmission type optical encoder device of the related art will be described with reference to FIG. In FIG. 18, a light source 1 is a light emitting unit such as a light or an LED, and is a unit that supplies stable light. The collimating lens 2 is for projecting the output light from the light source as a parallel light beam on a scale. Scale 3
Is a scale consisting of an optical grating with a constant lattice constant. The index scale 4 is a scale having the same lattice constant as the two scales 3 shifted by ４ wavelength to identify the moving direction of the scale 3. The photodetector 5 is 1/1 of the index scale 4
The detector is capable of detecting the light passing through two optical gratings shifted by four wavelengths. The moving direction 6 is an arrow indicating the moving direction of the scale 3. In the above configuration, usually, a slit or the like capable of moving the scale 3 is provided between the collimating lens 2 and the index scale 4, and the other light source 1 and the photodetector 5 of the collimating lens 2 and the index scale 4 are arranged. An integrated optical head is included in a light-shielded case. Then, with the positional relationship such that the light source unit and the light receiving unit of the optical head sandwich the scale 3, the light from the light source unit passes or is blocked by the movement of the scale 3, and the movement of the scale 3 is detected.
By placing the in a portion where the movement amount needs to be confirmed, the movement of that portion can be confirmed. At the time of detection, the light source 1 is turned on, and the light beam collimated by the collimator lens 2 is
The light passes through the scale 3 and the index scale 4 or is cut off, the passing light is received by the photodetector 5, and the cutoff light is not received by the photodetector 5. Then, the length, position, or movement amount can be detected by counting the number of ON / OFF of the light reception by a counter (not shown) or the like. The index scale 4 is an optical grating having a lattice constant of the same period as the two scales 3 shifted by ４ wavelength and installed between the photodetector 5 of the light receiving section and the scale 3 in order to know the moving direction of the scale 3. Therefore, when the light passing through each optical grating is detected by the photodetector 5 and each optical grating is A-phase and B-phase, the detection interval between the A-phase and the B-phase is shifted by 波長 wavelength. A short detection interval and a long detection interval shifted by 3/4 wavelength occur alternately. For example, the moving direction is determined based on which optical grating is detected after the long detection interval. Can be. FIG.
FIG. 11 is a diagram showing a reflection type optical encoder device in the related art. In the case of the reflection type, the output light from the light source 1 is reflected by the reflector 7 and detected by the photodetector 5,
In this case, the angular reflectance characteristic 8 shows a steep beam shape with strong directivity as shown in FIG.

[0003]

However, in the above-described conventional transmission-type configuration, the transmitted light is detected separately from the external light which is a noise component. It is necessary to make the interval between the scale 3 and the index scale 4 very small, and the optical head including the scale 3 and the index scale 4 (slit or the like)
Will be arranged so that the non-contact, parallel spacing is maintained. Even if the scale 3 moves with respect to the scale 3, mounting the optical head so that it always keeps a small interval usually involves mounting at an angle such as skew or yawing at the time of mounting. This is a task that requires a lot of man-hours with high difficulty.
Further, even in the case of the reflection type, as described above, the angular reflectance characteristic 8
Has a highly directional beam shape.
If there is a shift in the installation position or the angle of the light receiving surface, the detection sensitivity of the photodetector 5 will vary greatly. The present invention
In view of the above problems, an optical head capable of detecting the amount of movement by receiving light even if the scale slightly moves in a direction perpendicular to the direction of movement of the scale, or even if the scale or the optical head is slightly inclined. It is an object of the present invention to provide an optical encoder device.

[0004]

In order to achieve the above object, according to the present invention, a light source, a scale on which periodic position information is recorded by a light scattering portion and a non-scattering portion, and A light receiving unit that detects a change in the intensity of scattered light from the scale due to a change in the relative position of the light source and the scale; and a position that detects a change in the relative position of the scale from the detection result of the light receiving unit. It is characterized in that a change detecting means is provided, and instead of detecting a light blocking state and a transmitted light or reflected light receiving state, a scattered light receiving state and a light blocking state are detected. According to the second aspect of the present invention,
An optical path between the light source and the scale is provided with a light projecting lens for condensing light from the light source on the scale, and light to be diverged from the light projecting unit is collected. . According to a third aspect of the present invention, the light path between the scale and the light receiving means is provided with a light receiving lens for condensing the scattered light on the light receiving means, and receives the scattered light from the scale. Focus with a lens. In the present invention according to claim 4, an optical path to the scale of light emitted from the light source to the scale, and a light splitting unit for matching an optical path to a light receiving unit of a part of the scattered light of the scale, The optical path of the emitted light is made to coincide with the optical path to the light receiving means. According to a fifth aspect of the present invention, there is provided a single lens serving both as the light projecting lens and the light receiving lens, and the number of light projecting and light receiving lenses can be reduced to one. According to the present invention of claim 6, in the optical path between the light source and the scale, the light emitted from the light source has a short side on the scale corresponding to substantially a half cycle of the periodic position information of the scale. A slit mask for shaping the light beam so as to be projected on the scale as at least one rectangular light beam is provided, and the light beam is shaped into a rectangle by the slit mask. According to the present invention of claim 7, in a light path between the light source and the scale, light emitted from the light source has a short side on the scale corresponding to substantially a half cycle of periodic position information of the scale. The apparatus further comprises a cylindrical lens means for shaping at least one rectangular light beam so as to be projected on the scale, wherein the light beam is shaped into a rectangular shape by the cylindrical lens. According to an eighth aspect of the present invention, there is provided a cylindrical lens means or a wedge means for shaping a light beam incident on the light receiving means into a circular shape, and the light incident on the light receiving means is shaped into a circular shape. According to a ninth aspect of the present invention, the periodic position information of the scale is formed by a total reflection portion and a scattering portion, and the scale is defined as a total reflection portion and a scattering portion. According to a tenth aspect of the present invention, the periodic position information of the scale is formed by an absorbing part and a scattering part,
The scale is an absorption part and a scattering part. According to an eleventh aspect of the present invention, the scattering portion of the scale is formed by a two-dimensional or three-dimensional relief grating, and the amount of light reflected from the relief grating is constant.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. In all the following figures,
When a part having the same content as the part in the embodiment described once appears in another embodiment, the part is denoted by the same number, and the description is omitted. FIG. 1 is a perspective view showing a first embodiment of the optical encoder device of the present invention. As the light source 11, various laser light sources including a semiconductor laser, an LED, or the like can be used. However, when high resolution is obtained, for example, a laser beam such as a He-Ne laser is used, or another light source is used. It is desirable to use a condenser lens or the like to reduce the diameter of the condenser spot. When an LED is used, it is desirable that the LED has a light emitting area as small as possible and has no reflector structure. The scale 13 is composed of a transmission portion and a non-transmission portion used in a normal optical encoder device, and may have a pattern similar to that of a scale in which the transmission portion is an optical grating having a rectangular periodic structure. It is necessary that the portion is not a total reflection or absorption but a scattering portion. The structure of the scattering section may be of any material, shape, etc., but if high resolution is required, the scattering pattern of the scattering section must be miniaturized. Photodetector 1
5 can use a photodetector similar to a photodiode used in an ordinary optical encoder device.
The beam irradiation position 16 is an irradiation position of the beam from the light source 11 on the scale 13, and the scattered light at that position is received by the photodetector 15. The beam emitted from the light source 11 is scattered at the beam irradiation position 16 on the scale 13, and a part of the scattered beam is detected by the photodetector 15, and the position of the scale 13 is moved based on the detection result. Is detected. Note that a position change detection device that detects a change in the relative position of the scale from the detection signal of the scattering portion and the detection signal of the transmission portion, which is the detection result of the photodetector 15, is the same as a conventional detection device. For example, a threshold is set between the detection level of the scattered light and the detection level of the transmitted light, and the movement is detected depending on whether the detection value of the photodetector 15 is higher or lower than the threshold. It is possible.

FIG. 2 is a side view for explaining the scattered light of the embodiment of FIG. In FIG. 2, when the beam from the light source 11 reaches the beam irradiation position 16, the beam irradiation position 16 is a scattering portion, so that the beam is scattered by the scattering pattern to become scattered light 17. The scattered light 17 is detected. Next, when the scale 13 is moved and the beam of the light source 11 ′ reaches the beam irradiation position 16 ′, the beam of the light source 11 ′ passes through the transmission part of the scale 13. Detector 1
At 5 ', the scattered light 17 is not detected. FIG. 3 is a diagram for explaining the angular reflectance characteristic of the scattered light 17 in FIG. 2, and corresponds to the angular reflectance characteristic 8 in the conventional reflection type of FIG. Angular reflectance characteristic 9 in FIG.
Differs from the steep angular reflectance characteristic 8 shown in FIG. 19, and shows a characteristic close to a circle as shown. Scale 13
For the upper scattering portion, it is desirable to use a perfect diffuse reflection surface ideally from the viewpoint of light use efficiency and detection stability. The perfect diffuse reflection surface is a scattering surface having a light intensity I = Incos θ and a reflectance of 1, where In is the light intensity in the normal direction and θ is the angle when the normal direction is 0 °. It is. As an example of the perfect diffuse reflection surface, optically frosted glass, a reflection plate for liquid crystal, a plaster surface, etc. show similar characteristics. Although the perfect diffuse reflection surface is ideal as described above, it is not always necessary to use the perfect diffuse reflection surface in order to obtain the effects of the present invention.
This is because the present invention uses a scattering surface in order to avoid a steep angle characteristic of total reflection of light as shown in FIG. Therefore, for example, instead of a high-reflectance surface such as an aluminum surface having a reflectance of 90% or more, a light-absorbing surface with a reflectance of about 50% is used, and the light receiver is not reflected light,
The effect of the present invention can be obtained by using an arrangement that receives scattered light.

FIG. 4 is a top plan view showing how the beam irradiation position in FIGS. 1 and 2 changes. In FIG. 4, when the scale 13 moves in the direction of the arrow, the beam irradiation position 16 moves from the scattering part shown by the solid circle to the transmission part shown by the dotted circle. The scattered light 17 has been detected by the light detection unit 15 shown in the figure, but cannot be detected. FIG. 5 is a diagram showing a case where the scale of FIG. 4 is provided with an index scale function for specifying the traveling direction. In FIG. 5 (a), the transmission portion and the scattering portion of the scale 14 are formed, for example, like a conventional index scale, by dividing two divided scales by a line parallel to the traveling direction of the scale with a 周期 period shift. The phase read by the photodetector 15 is detected separately in the A phase and the B phase. The beam irradiation position 16 is applied to an intermediate position where the beam is distributed and evenly applied to both of the two parts of the transmission part and the scattering part, and the scale 14
Moves the beam on an intermediate line that separates the transmission part and the scattering part into two parts. In FIG. 5B, the photodiode 14 in the photodetector 15 is adjusted to match the divided scale of the scale 14 in FIG. 5A so that each phase (A phase and B phase) can be detected. The divided photodiode 18 is obtained. The detection of the moving direction by the phase can be performed by the same method as in the related art.

FIG. 6 is a perspective view showing a second embodiment of the optical encoder device of the present invention. The difference between the first embodiment and the second embodiment is that the light emitted from the light source 11 is condensed and the desired beam diameter is adjusted to the scale 13.
It has a light projecting lens 12 to be formed thereon. The light projecting lens 12 has a light source 11 in terms of light use efficiency.
A lens having an aperture larger than the divergence angle is desirable. From the viewpoint of improving the resolution, it is desired to select a lens that forms a spot as small as possible on the scale 13. By using the light projecting lens as in the second embodiment, the beam diameter of the beam irradiation position 16 on the scale 13 can be reduced, so that the resolution as an optical encoder can be increased. Even if a divergent LED or a semiconductor laser is used as the light source 11, the light can be condensed and a small-diameter beam spot can be formed on the scale 13, so that the optical encoder device can be reduced in size and cost. The effect is obtained. The operation of the second embodiment is the same as that of the first embodiment.

FIG. 7 is a perspective view showing a third embodiment of the optical encoder device of the present invention. A first embodiment,
The difference between the second embodiment and the third embodiment is that the light emitted from the light source 11 of the second embodiment is condensed to form a desired beam diameter on the scale 13. In addition to having a light projecting lens 12, a light receiving lens for collecting light scattered from the scale 13 and forming a desired beam diameter on a light receiving portion of the photodetector 15. 14. The opening of the light receiving lens 14 is desirably a lens having an opening larger than the opening of the light receiving lens used in an optical encoder device of a type that detects reflected light from a normal scale. In a general scale reflected light type light receiving lens, for example, when the focal position of the beam projected on the scale is the beam irradiation position on the scale, the light receiving side has the same size as the aperture of the light projecting lens. Light having a beam diameter is detected as reflected light, and it is considered that a lens having an opening equivalent to a light projecting lens is sufficient. However, in the case of the present invention, since a scattering pattern is formed on the scale 13 instead of a reflection pattern, the intensity of light is different between the reflected light in the reflection pattern and the scattered light in the scattering pattern. Is much weaker than the reflected light. In order to efficiently detect this weak scattered light, a light receiving lens having a relatively large aperture is required as compared with the reflected light detection type.
Increasing the aperture of the light receiving lens also increases the allowable amount with respect to the alignment error of the optical head, the inclination of the scale, and the like.

FIG. 8 is a side view showing a fourth embodiment of the optical encoder device according to the present invention. The difference in configuration between the fourth embodiment and the third embodiment is that the light emitted from the light source 11 and the scattered light from the scale 13 have the same optical axis so that the projected light and the scattered light (the reflected light ) Optical axis scale 13
That is, a beam splitter 19 for making the beam vertical is inserted on the optical path. As shown in FIG. 8, the beam splitter 19 is disposed so that an emission optical axis from the light source 11 and an incidence optical axis to the photodetector 15 intersect at right angles. The beam emitted from the light projecting unit 11 passes through the light projecting lens 12, and has a light amount of about 50
% Is bent at a right angle and irradiates the scale 13 vertically. The beam scattered by the scattering portion on the scale 13 returns along the same path as the light projection, passes through the beam splitter 19, is condensed by the light receiving lens 14, and is received by the photodetector 15. Here, in the present embodiment, the reason why the optical axes of the outgoing light and the scattered light (reflected light) are perpendicular to the scale 13 along the same path is that light scattering at the scattering portion of the scale 13 is generally caused by total internal reflection. If the direction is 0 °, (cos θ)
^Since the scattering intensity distribution is proportional to ² , it is desirable to detect scattered light from the direction of total reflection when detecting scattered light. In addition, in the present embodiment, in addition to an increase in the tolerance for the above-described alignment error of the optical head and the inclination of the mounting of the scale, the optical head can be downsized by the right angle arrangement of the light emission and the light reception. Therefore, the adjustment can be facilitated as compared with the case where the light projecting unit and the light receiving unit are separately provided.

FIG. 9 is a side view showing a fifth embodiment of the optical encoder device of the present invention. The configuration difference between the fifth embodiment and the fourth embodiment is that the light projecting lens 12 for condensing the light emitted from the light source 11 and the light receiving lens for condensing the scattered light from the scale 13 are shared. Thus, one projection / light reception lens 20 is formed. This figure 9
Light source 11, photodetector 15 and beam splitter 1
By arranging 9, it becomes possible to use one lens for light emission and light reception, and as a result, it is possible to further reduce the size and the adjustment of the optical head, and to further reduce the number of parts. Become.

FIG. 10 is a side view showing a sixth embodiment of the optical encoder device according to the present invention, and FIG.
FIG. 4B is a top view of FIG. The configuration difference between the sixth embodiment and the fifth embodiment is that the light source 11 and the beam splitter 1
Slit mask 21 having a rectangular slit between 9
Is the point where If the insertion position is described in consideration of other embodiments, the slit mask 21 is provided between the light source 11 and the light projecting lens 12 or between the light projecting lens 12 and the scale 13 and the beam splitter 19. If used, it is inserted into the light source 11 side. The slit mask 21 turns the beam shape 22 on the scale 13 into a rectangular shape. In this way, by setting the beam shape on the scale to a pattern that is long at right angles to the moving direction of the scale, it is possible to determine that a part of the scale has a defect. Also, stable detection is possible with little change in light quantity. 11A and 11B are a top view of a slit mask and a top view of a scale 13 showing a seventh embodiment for forming a plurality of beams from the slit mask for forming a single rectangular beam in FIG. . FIG.
In the case of (1), since a plurality of slits are formed in the slit mask 23, a plurality of beam irradiations are formed on the scale 13. Thus, the slit mask 23
By forming a plurality of beams, the use efficiency of the light emitted from the light source 11 is increased, and even if there is a defect in a part of the transmission part or the scattering part of the scale 13, it can be compensated by another beam. The stability of detection is improved.

FIG. 12 is a side view showing an eighth embodiment of the present invention in which the slit mask of FIG. 10 is a cylindrical lens. Since the cylindrical lens 25 is a lens having a shape obtained by cutting off a cylindrical side surface, an elongated beam is obtained because the formed beams have different vertical and horizontal converging angles. As a result, the slit mask shown in FIG. A beam shape similar to the formed beam is obtained. In FIG. 12, a cylindrical lens 25 is used instead of the slit mask 21.
Is used, light that is blocked and wasted in the case of a slit mask can be used, and the efficiency of use of light emitted from the light source 11 increases. When the light projecting lens 12 is used as shown in FIG. 12, the number of parts can be reduced and the size can be reduced by integrating the light projecting lens 12 and the cylindrical lens 25. Further, a plurality of beams can be formed by using a plurality of cylindrical lenses 25 as shown in FIG.

FIG. 13 is a plan view of a light receiving surface of a photodetector showing a ninth embodiment for receiving a rectangular or elongated beam shown in FIGS. In FIG. 13, the light receiving lens 14 (not shown) is changed to a cylindrical lens or the wedge is inserted in front of the photodetector 15 to shorten the long side of the rectangular beam or the long side of the elongated beam. , The beam is incident on the photodetector 15. Accordingly, the light receiving surface of the ninth embodiment is small like a circular beam 28 in the light receiving surface shape 26. On the other hand, a beam which is elongated by the conventional slit mask 21 and cylindrical lens 25 and is irradiated on the light receiving surface is received as an elongated beam 27. In addition, since the shape of the light receiving surface is generally a square or a circle, the light receiving surface required to receive a conventional elongated beam has a light receiving surface shape 25. Light receiving surface shape 2
In the case of an area having a large light receiving area as shown in FIG. 5, the detection speed is reduced, which causes erroneous detection of disturbance light, and the S / N ratio of the detection signal is deteriorated. I do. FIG. 14 is a diagram in which a cylindrical lens is inserted to shorten the incident light of the photodetector 15 of the eighth embodiment of FIG. 12 as shown in FIG. FIG. 14 (a)
14B, the long side of the rectangular beam is shortened by the cylindrical lens 29 where the rectangular beam like the beam shape 22 in FIG. Circular beam 2 as shown in FIG.
8 can be obtained.

FIG. 15 is a view in which a wedge 30 is inserted to shorten the incident light of the photodetector 15 of the eighth embodiment of FIG. 12 as shown in FIG. By configuring as shown in FIG. 15A, the beam shape 2 shown in FIG.
When a rectangular beam such as 2 is incident on the photodetector 15, the long side of the rectangular beam is shortened by the wedge 30, and a circular beam 28 as shown in FIG. 13 can be obtained. However, when the wedge 30 is inserted, since the optical axis of the long side of the rectangular beam is bent as shown in the figure, the photodetector 15 needs to be installed with an offset. FIG.
Shows a tenth embodiment in which the transmission part in the scale of the third embodiment of FIG. 7 is replaced by a reflection part. It should be noted that the case where the transmissive portion of the other embodiment is replaced with the reflective portion can be performed in the same manner as in the present embodiment. In the scale 31 of FIG. 16, the scattered light 17 of the scattering unit 16 is the same as in the other embodiments, but the reflected light 33 is obtained by using the part that was the transmission unit in the other embodiments as the reflection unit 32. As the member of the reflecting portion 32, a member having as little scattering as possible and having a high reflectance is desirable, but a general metal film, a dielectric multilayer film or the like can be used. When the scale 31 is constituted by the scattering section 16 and the reflection section 32, the scattering and reflection of light depends on the material of the base material of the transmission section as compared with the case of the other transmission section and the scattering section. It is possible to eliminate the fact that the noise component is likely to occur due to. As a result, S / N
A high ratio can be secured. In the embodiment in which the scattered light is detected, if the amount of the received light is too large if all the reflected light is received, the arrangement of the light receiving unit and the light projecting unit is changed so that the totally reflected light is incident on the light receiving unit. You need to avoid it. Further, although not shown in particular, since the drawing is similar, it is possible to solve the problem that the noise component is easily generated even when the reflecting portion 32 is replaced with the absorbing portion. As a result, the S / N ratio is reduced. Can be kept high. As the member of the absorbing portion, it is desirable that the scattering is as small as possible,
If the same scattered substance has a high concentration and a small reflection, it can be used. For example, even if black lines are periodically formed on paper, it can be used. In that case,
Since the scale is formed by changing the concentration of paper or a normal scatterer, it is inexpensive and easy to handle.

FIG. 17 is a diagram showing an eleventh embodiment in which the scattering portion on the scale is a sinusoidal relief grating. In FIG. 17, in the scale 34, a sine-wave scattered object 36 is formed by a two-dimensional or three-dimensional relief grating in a sine wave shape in order to enable detection with a high S / N ratio by removing a noise component. The irradiation light 35 is scattered by being reflected by the curved surface of each of the sinusoidal scatterers 36 formed on the scale 34 to be scattered light 37. Since each of the sine-wave scattered objects 36 is similarly formed in a sine-wave shape, reflection of a scattered light having a constant amount of reflected light in all directions from vertical incidence to acute incidence is obtained. As a method of creating the sine wave pattern, processes such as a two-beam interference exposure method for forming a normal diffraction grating, a ruling engine, and a mask exposure can be used. When the sinusoidal relief grating of the present embodiment is used as a scattering part, it is desirable that the surface of the scale 34 other than the scattering part is a total reflection part. By using a sine-wave scattered object 36 having a three-dimensional relief structure instead of a linear pattern as the scattering pattern as in the present embodiment, stable signal detection with less unevenness is possible. As described above, by using each of the above embodiments to detect the scattered light, a flexible and easy arrangement of the optical head and the scale in the optical encoder device becomes possible, and the light use efficiency of the light source is improved. , And miniaturization and cost reduction are promoted, and stable signal detection becomes possible. In the present embodiment, detection of linear movement is described. However, the present invention is not limited to this, and other movements that detect movement of a position by detecting scattered light, for example, detection of rotation movement Etc. can also be used.

[0017]

As described above, according to the first aspect of the present invention, the light blocking state and the transmitted light or reflected light receiving state are not detected but the scattered light receiving state and the light blocked state are detected. Is strong against misalignment between the light-emitting part and light-receiving part or the scale, and is difficult to install the conventional optical head when mounting it at an angle or when the distance between the scale and the head is required. It is now possible to respond. According to the second aspect of the present invention, since the light from the light projecting portion is collected, the utilization efficiency of the projected light is improved, and a divergent light source such as an LED or a semiconductor laser can be used. As a result, it is possible to further reduce the size and cost. According to the third aspect of the present invention, efficient light reception is achieved by condensing the scale scattered light with the light receiving lens. According to the fourth aspect of the present invention, since the light path of the emitted light and the light path to the light receiving unit are made to coincide with each other, the light use efficiency is improved, and stable measurement becomes possible.
The optical head can be reduced in size. According to the fifth aspect of the present invention,
Since the light-emitting and light-receiving lenses can be integrated into one, the number of components can be reduced and the size of the apparatus can be reduced. According to the sixth aspect of the present invention, since the light beam is shaped into a rectangle by a slit mask, even if there is a defect in a part of the scale, a change in the amount of light due to the defect is reduced, and stable detection is possible. Becomes According to the seventh aspect of the present invention, the light beam is shaped into a rectangular shape by the cylindrical lens. Therefore, even if a part of the scale has a defect,
The change in the amount of light due to the defect is reduced, and stable detection becomes possible. According to the eighth aspect of the present invention, since the light incident on the light receiving means is shaped into a circle, the area of the photodetector can be reduced, so that the signal detection speed can be improved. According to the ninth aspect of the present invention, by using the scale as a total reflection portion and a scattering portion, a higher S / N ratio can be obtained as compared with a case having a transmission portion. According to the tenth aspect of the present invention, by using the scale as the absorbing portion and the scattering portion, the scattering of light can be set to a constant amount, the noise component can be easily removed, and the scale can be provided at low cost and easy to handle. According to the eleventh aspect of the present invention, since the amount of reflected light from the relief grating is constant, stable signal detection is possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of an optical encoder device according to the present invention.

FIG. 2 is a side view for explaining scattered light in the embodiment of FIG.

FIG. 3 is a diagram for explaining an angular reflectance characteristic of scattered light 17 in FIG. 2;

FIG. 4 is a plan view seen from above showing how the beam irradiation position in FIGS. 1 and 2 changes.

5A and 5B are diagrams showing a case where the scale of FIG. 4 is provided with an index scale function for specifying a traveling direction.

FIG. 6 is a perspective view showing a second embodiment of the optical encoder device of the present invention.

FIG. 7 is a perspective view showing a third embodiment of the optical encoder device of the present invention.

FIG. 8 is a side view showing a fourth embodiment of the optical encoder device according to the present invention.

FIG. 9 is a side view showing a fifth embodiment of the optical encoder device of the present invention.

FIGS. 10A and 10B are side views showing a sixth embodiment of the optical encoder device of the present invention.

11A and 11B are top views showing a seventh embodiment in which the slit mask for forming a single rectangular beam in FIG. 10 is replaced with a slit mask for forming a plurality of beams.

FIG. 12 is a side view showing an eighth embodiment of the present invention in which the slit mask of FIG. 10 is a cylindrical lens.

FIG. 13 is a plan view of a light receiving surface of a photodetector showing a ninth embodiment for receiving a rectangular or elongated beam shown in FIGS. 10 to 12;

FIGS. 14A and 14B are diagrams in which a cylindrical lens is inserted to shorten the incident light of the photodetector 15 of the eighth embodiment of FIG. 12 as in the ninth embodiment of FIG. 13; It is.

FIGS. 15A and 15B are diagrams in which a wedge is inserted to shorten the incident light of the photodetector 15 of the eighth embodiment of FIG. 12 as in the ninth embodiment of FIG. 13; is there.

FIG. 16 shows a tenth embodiment in which the transmitting part in the scale of the third embodiment of FIG. 7 is replaced by a reflecting part.

FIG. 17 is a diagram showing an eleventh embodiment in which a scattering portion on a scale is a sinusoidal relief grating.

FIG. 18 is a perspective view showing a transmission type optical encoder device in the related art.

FIG. 19 is a diagram showing a reflection type optical encoder device in the related art.

[Explanation of symbols]

1, 11, 11 ': light source, 2: collimating lens, 3, 13, 31, 34: scale, 4: index scale, 5, 15, 15': photodetector, 6: scale moving direction, 7: reflective object,
8, 9 ... Angle reflection characteristics, 12 ... Light projection lens, 1
4: light receiving lens, 16, 16 ': irradiation position of beam, 17, 37: scattered light, 18: split photodiode, 19: beam splitter, 20 ...
・ Projection / light reception lens, 21 ・ ・ ・ Slit mask, 22 ・
..Beam shape on the scale, 22 ': multiple beam shape on the scale, 23: multiple slit mask, 24,
29: Cylindrical lens, 25: Shape of light-receiving surface for elongated beam, 26: Shape of light-receiving surface for circular beam,
27 ・ ・ ・ Elongated beam, 28 ・ ・ ・ Circular beam, 30 ・
..Wedge, 33 ... total reflection light, 35 ... irradiation light, 36 ... sinusoidal scattering object

Claims (11)

[Claims] 1. A scale on which periodic position information is recorded by a light source, a light scattering portion and a non-scattering portion, and a scale of scattered light from the scale accompanying a change in a relative position between the light source and the scale. An optical encoder device comprising: a light receiving means for detecting a change in intensity; and a position change detecting means for detecting a change in a relative position of the scale from a detection result of the light receiving means. 2. The optical encoder according to claim 1, wherein a light projecting lens for condensing light from the light source on the scale is provided in an optical path between the light source and the scale. apparatus. 3. The optical system according to claim 1, wherein a light receiving lens for condensing the scattered light on the light receiving means is provided in an optical path between the scale and the light receiving means. Encoder device. 4. A light splitting means for matching an optical path of the light emitted from the light source to the scale and an optical path of a part of the scattered light of the scale to a light receiving means. The optical encoder device according to any one of claims 1 to 3. 5. The optical encoder device according to claim 4, further comprising one lens serving as both the light projecting lens and the light receiving lens. 6. An optical path between the light source and the scale includes at least one short side on which the light emitted from the light source has a short side corresponding to substantially a half cycle of periodic position information of the scale. The optical encoder device according to any one of claims 1 to 5, further comprising a slit mask for shaping the light beam so as to be projected on the scale as a rectangular light beam. 7. An optical path between the light source and the scale includes at least one short side on which the light emitted from the light source has a short side corresponding to substantially a half cycle of periodic position information of the scale. The optical encoder device according to any one of claims 1 to 5, further comprising a cylindrical lens unit configured to shape a rectangular light beam so as to be projected on the scale. 8. An optical encoder according to claim 1, further comprising a cylindrical lens means or a wedge means for shaping a light beam incident on said light receiving means into a circular shape. apparatus. 9. The optical encoder device according to claim 1, wherein the periodic position information of the scale is formed by a total reflection portion and a scattering portion. 10. The periodic position information of the scale,
The optical encoder device according to claim 1, wherein the optical encoder device is formed by an absorption unit and a scattering unit. 11. The optical encoder device according to claim 9, wherein the scattering portion of the scale is formed by a two-dimensional or three-dimensional relief grating.