JP2002048602A - Optical encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical encoder of smaller size at a lower price. SOLUTION: An optical linear encoder 100 comprises an encoder head 102 comprising an optical system for detecting movement, and a movable scale 104 which translates relative to the encoder head 102, with them arranged parallel to each other with a constant interval. The movable scale 104 comprises an optical pattern 112 for detecting movement which is formed on the surface of a substrate 110 which is optically transparent, and an optical pattern 114 for detecting a reference position. The encoder head 102 comprises a coherent light source 122, an optical detector 124 for detecting movement, and an optical detector 126 for detecting a reference position. The coherent light source 122 is a surface luminous laser of a single body, as an example, and it is fixed to a semiconductor substrate 120 where the optical detectors 124 and 126 are formed by such means as with an adhesive, as an example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical displacement sensor using optical means, and more particularly to an optical encoder.

[0002]

2. Description of the Related Art At present, in a stage of a machine tool or a three-dimensional measuring instrument, a linear displacement amount is detected.
In a servomotor or the like, a so-called encoder of an optical type or a magnetic type for detecting a rotation angle is used.

[0003] An optical encoder generally includes a scale fixed to a member such as a stage for which displacement is to be detected, and a sensor head for detecting displacement of the scale. The sensor head has a light source for irradiating the scale with a light beam, and a photodetector for detecting diffracted light transmitted through or reflected by the scale. Detects movement.

[0004] As a first prior art, a typical optical encoder will be described. FIG. 32 is a configuration diagram of an encoder using a surface emitting laser and a reflection scale as an example of a small-sized and low-cost laser encoder that does not require an optical component such as a lens. For a laser encoder using the surface emitting laser and the reflection type scale, see, for example, a dissertation “Microencoder using a surface emitting semiconductor laser” (Eiji Yamamoto, Optics Vol. 27, No. 6)
(1998)).

As shown in FIG. 32, the encoder 10 includes a reflective scale 12 and a sensor head 14.
It is composed of The sensor head 14 includes a surface emitting laser 16 and a photodetector 18, both of which are
0, and the relative positional relationship between the surface emitting laser 16 and the photodetector 18 is kept constant. Scale 12
Has a pattern in which the reflectance periodically changes in a direction perpendicular to the paper surface. This pattern is formed by patterning a highly reflective member such as aluminum on the surface of a transparent substrate such as glass.

The scale 12 reciprocates relative to the sensor head 14 in a direction perpendicular to the plane of FIG. 32 in conjunction with a stage (not shown) or the like. It is detected from the change in the intensity of the reflected light. The light beam emitted from the surface emitting laser 16 is reflected by the scale 12, and the reflected light is
Is received by the Since the reflectance of the pattern on the scale 12 changes periodically in a direction perpendicular to the paper surface, the displacement of the scale can be detected from the change in the intensity of the reflected light received by the photodetector 18.

Next, as a second prior art, a laser encoder using a coherent light source and a diffraction grating scale will be described. FIG. 33 is a configuration diagram of a laser encoder using a coherent light source and a diffraction grating scale, which is an example of a small-sized and low-cost encoder that does not require an optical component such as a lens. For a laser encoder using this coherent light source and diffraction grating scale, for example,
It is described in "Copal: Rotary Encoder Catalog".

In this laser encoder 30, FIG.
As shown in FIG. 3, a laser beam emitted from a semiconductor laser 32 which is a coherent light source is irradiated on a transmission type diffraction grating scale 34, whereby a diffraction interference pattern 36 is generated on a light receiving surface of a photodetector 40. Is done.

As shown in FIG. 33, each configuration parameter is defined as follows.

Z1: the distance between the light source and the diffraction grating on the scale z2: the distance between the diffraction grating on the scale and the photodetector p1: the pitch of the diffraction grating on the scale p2: the diffraction interference pattern on the light receiving surface of the photodetector Pitch The “pitch of the diffraction grating on the scale” means a spatial period of a pattern formed on the scale and having modulated optical characteristics. Further, “the pitch of the diffraction pattern on the light receiving surface of the photodetector” means the spatial period of the intensity distribution of the diffraction pattern generated on the light receiving surface.

According to the theory of light diffraction, when z1 and z2 defined as described above have a specific relationship satisfying the relationship shown in the following equation (1), a similarity to the diffraction grating pattern of the scale 34 is obtained. An intensity pattern is generated on the light receiving surface of photodetector 40.

[0012] (1 / z1) + (1 / z2) = λ / kp1 2 ··· (1) where, lambda is the wavelength of the light beam emitted from the light source, k is a natural number.

At this time, the pitch p2 of the diffraction interference pattern on the light receiving surface is determined by using other constituent parameters as follows.
It can be expressed as shown in equation (2).

P2 = p1 (z1 + z2) / z1 (2) When the scale is displaced in the pitch direction of the diffraction grating with respect to the light source, the intensity distribution of the diffraction interference pattern is displaced in the scale while maintaining the same spatial period. Move in the direction you want.

The photodetector 40 has a plurality of light receiving areas 42. The light receiving areas 42 are arranged in parallel with the moving direction of the scale 34 with a spatial period p20.
20 is equal to the pitch p2 of the diffraction grating scale. Therefore, every time the scale 34 moves by p1 in the pitch direction, an intensity signal that periodically changes at a period p2 is obtained from the photodetector 40. As a result, the amount of displacement of the scale 34 in the pitch direction is detected.

The optical encoder has high precision, high resolution,
It is used in various fields because it is a non-contact type and has excellent characteristics such as excellent resistance to electromagnetic interference.Especially, optical encoders have become the mainstream for encoders that require high precision and high resolution. I have.

[0017]

However, the conventional optical encoder has the following problems.

In the first conventional example, it is necessary to use a dedicated fixing stand for disposing the light source at an angle to the scale, which makes assembly difficult and increases the cost. In addition, the distance between the light source and the scale, the so-called gap, must be strictly adjusted. Otherwise, the reflected light from the scale does not enter a predetermined portion of the photodetector, and adversely affects the signal intensity and accuracy. I will. Furthermore, when trying to arrange the light source and the light receiving area of the photo detector close to each other in order to reduce the size of the sensor head, the reflected light beam from the scale may be blocked by the edge of the surface emitting laser chip, which is the light source. It may not reach the light receiving area. Further, in order to avoid such a situation, it is necessary to further increase the mounting angle of the light source. After all,
It is difficult to reduce the size and price.

In the case of the configuration shown in the second conventional example, expensive optical parts such as slits are used, and it is necessary to assemble these optical parts with high precision. Pricing is extremely difficult.

In each of the first and second conventional examples, when information is read from a scale on which a plurality of optical patterns are formed, the same number of light sources as the number of optical patterns are used, or a beam is split using a beam splitter or the like. And it is more difficult to reduce the size and cost.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an optical encoder which is reduced in size and cost. More specifically,
It is an object of the present invention to provide an optical encoder which does not require the light source to be inclined with respect to the scale and does not require strict accuracy for adjusting the gap between the scale and the head.

[0022]

An optical encoder according to the present invention is a linear encoder on one side, and a movable scale on which an optical pattern of a predetermined period is formed, and a light beam of a predetermined shape on the optical pattern surface. A coherent light source that emits light perpendicularly, and a light detection unit that receives a light beam from the light source reflected by the optical pattern and detects a diffraction pattern generated on a light receiving surface by the optical pattern. I have.

The optical encoder according to the present invention is, in another aspect, a rotary encoder, in which an optical pattern having a predetermined period in the circumferential direction of rotation is formed, and a rotatable scale is provided on the optical pattern surface. A coherent light source that irradiates a light beam of a predetermined shape substantially vertically, and a light detection that receives a light beam from the light source via the optical pattern and detects a diffraction pattern generated on a light receiving surface by the optical pattern. Means.

Another optical linear encoder according to the present invention includes a movable scale on which an optical pattern having a predetermined period is formed, a coherent light source for irradiating a light beam of a predetermined shape onto the optical pattern surface, and Light detecting means for receiving a light beam from the light source and detecting a diffraction pattern generated on the light receiving surface by the optical pattern, wherein the light detecting means does not receive light of a main axis of the light beam. It is configured as follows.

[0025] Still another optical linear encoder according to the present invention includes a coherent light source that emits a light beam having a predetermined shape, and a relative displacement so as to cross the light beam emitted from the coherent light source. And a scale formed with an optical pattern of a predetermined period for generating a diffraction interference pattern by the light beam, and a photodetector for detecting a predetermined portion of the diffraction interference pattern generated by the optical pattern, from the coherent light source The length of the main axis of the light beam directed to the optical pattern formed on the scale is z1, the length of the main axis of the light beam directed from the optical pattern formed on the scale to the light receiving area of the photodetector is z2, When the pitch of a predetermined portion of the optical pattern formed on the scale is p1, n is a natural number, the light receiving area of the photodetector is the light receiving area. Substantially in the pitch direction of a predetermined portion of the diffraction interference pattern formed on the rear np1 (z1 +
An optical encoder having light intensity detection means constituted by a light receiving area group having a light receiving area at a position of z2) / z1, wherein the light receiving area group of the photodetector is formed on the light receiving area. For diffraction interference patterns,
In the vicinity of the main axis of the light beam, there is no effective light detection sensitivity or the light beam is shielded.

Another optical rotary encoder according to the present invention is rotatable relative to the photodetector, and is formed so that at least optical characteristics such as reflection, transmission, and diffraction change periodically. A rotary scale, a light source for irradiating the rotary scale, and a photodetector having a light receiving area for receiving a predetermined area of reflected light, transmitted light, or diffracted light from the rotary scale; In an optical rotary encoder that detects a light-dark pattern due to reflected light, transmitted light, or diffracted light from a light-receiving area of the photodetector, the light source is disposed substantially on an extension of a rotation axis of the rotary scale.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

The first embodiment is a reflection type optical linear encoder, which will be described with reference to FIGS.

As shown in FIG. 1, an optical linear encoder 100 according to the present embodiment includes an encoder head 102 including an optical system for detecting a movement, and a movable scale 10 that can translate with respect to the encoder head 102.
4 is provided.

The movable scale 104 is formed on a surface of an optically transparent substrate, for example, a glass substrate 110, and is provided with a first optical pattern 112 for detecting the movement of the scale 104.
And a second optical pattern 114 for detecting the reference position of the scale 104.

The first optical pattern 112 is a scale 1
It extends over substantially the entire scale 104 along the direction of movement of the scale 104, and has a reflectance that changes at a constant period p1 along the direction of movement of the scale 104. The first optical pattern 112 is formed by, for example, forming a thin film of the same width, such as a metal having a high reflectance, on the transparent substrate 110 at regular intervals (for example, p1 / 2). Is done.

The second optical pattern 114 has a scale 1
It exists only in a part of the scale 104 in the movement direction of the scale 104 and has a light condensing action in the movement direction of the scale 104. The second optical pattern 114 is, for example, a holographic pattern, for example, a cylindrical hologram lens.

The encoder head 102 includes a light source that emits coherent light, that is, a coherent light source 122, and first light detection means or light for detecting movement for detecting reflected light from the first optical pattern 112. A detector 124 and second light detecting means or light detector 1 for detecting a reference position for detecting reflected light from the second optical pattern 114.
26, which are both held on the substrate 120.

For example, the substrate 120 is, for example, a semiconductor substrate, and both the first photodetector 124 and the second photodetector 126 are formed on the semiconductor substrate 120. Coherent light source 1
Reference numeral 22 denotes a single surface emitting laser, for example, which is fixed to a flat substrate 120 by means such as bonding. That is, the light source 122 and the photodetectors 124 and 126
0 is provided for the hybrid. Since the surface emitting laser 122 is fixed to the flat substrate 120, the mounting can be easily performed.

The coherent light source 122 is preferably a surface emitting laser, but is not limited to a surface emitting laser, and may be an edge emitting laser or a light emitting diode (LED). However, a surface emitting laser can emit a light beam of a desired shape without using an optical component such as a lens, and is particularly suitable for the purpose of miniaturization.

In other words, the encoder head 102 and the movable scale 104 are composed of a substrate 120 and a transparent substrate 110.
Are arranged parallel to each other at a certain interval.
Therefore, the light beam 142 emitted from the surface emitting laser 122 irradiates the surface of the scale 104 substantially perpendicularly. That is, the main axis 128 of the light beam 142 traveling from the surface emitting laser 122 to the movable scale 104 is substantially perpendicular to the movable scale 104.

As shown in FIG. 2, the first photodetector 124 includes a plurality of light receiving areas 130, or in other words, light receiving elements such as photodiodes. The plurality of light receiving areas 130 include a first light receiving area group 132
, A second light receiving area group 134, a third light receiving area group 136, and a fourth light receiving area group 138.

The light receiving areas belonging to the same light receiving area group are p
The two light receiving areas are arranged at a pitch of p2 / 4. More generally, the light receiving areas of the same light receiving area group are p2 × n (n = 1,
2, 3,...), And two adjacent light receiving areas are arranged at a pitch of (p2 / 4) × m (m = 1, 2, 3,...).

The light receiving areas of each light receiving area group are arranged in a comb-like shape, and are arranged so as to mesh with the light receiving areas of the other light receiving area groups.

The light receiving areas of the same light receiving area group are electrically connected to each other.
⁺ , The second light receiving area group 134 outputs an A ⁻ signal, the third light receiving area group 136 outputs a B ⁺ signal, and the fourth light receiving area group 138 outputs a B ⁻ signal. Here, A ^- signal means a reverse signal or signals whose phases are shifted 180 degrees A ⁺ signal. B ^- relationship between the signal and the B ⁺ signal in the same manner.

[0041] These signals are processed by a (not shown) signal processing circuit, A ⁺ signal and A ^- A by the subtraction of the signal
Phase signal is generated, B ⁺ signal and B ^- B by the subtraction of the signal
A phase signal is generated. The signal processing circuit includes, for example, the semiconductor substrate 120 like the photodetector 124 and the photodetector 126.
It is good to be formed in.

As shown in FIG. 3, the second photodetector 126 has a single light receiving area 140, or in other words, a light receiving element such as a photodiode.

Next, returning to FIG. 1, the operation of the linear encoder according to the present embodiment will be described.

The light beam 142 emitted from the surface emitting laser 122 is applied to the movable scale 104 vertically,
A beam spot 144 is formed on the surface. A part 144a of the beam spot 144 always hits the first optical pattern 112, and the beam of the reflected light from the part 144a illuminates the first photodetector 124, and the light receiving surface thereof receives the first optical pattern 112. Is projected. This diffraction interference pattern 146
This is a light / dark pattern having a period of pitch p2 = p1 (z1 + z2) / z1. The light / dark pattern moves on the light receiving area 130 of the photodetector 124 in parallel with the moving direction of the scale 104 as the scale 104 moves.

As described above, the first photodetector 124
Has a plurality of light receiving areas 130 including first to fourth light receiving area groups, and based on the output of each light receiving area group, as shown in FIG. A signal is generated. The A-phase signal and the B-phase signal each reflect the phase of the diffraction interference pattern 146 at a specific position, and both have a period of one quarter of the period p of the diffraction interference pattern 146, that is, a phase of 90 degrees. It is out of alignment. A Lissajous figure is obtained from the A-phase signal and the B-phase signal as shown in FIG.

When the A-phase signal and the B-phase signal are approximated to a sine wave, the Lissajous figure is circular. Point P in FIG. 4 (B)
Shows the position of the scale 104 relative to the photodetector 124 at a certain point in time.
Moves on the circumference of this Lissajous figure according to the movement of. Furthermore, the speed and direction of the movement of the point P
4 depends on the speed and direction of movement. Therefore, the moving speed and moving direction of the scale 104 can be detected based on the moving speed and moving direction of the point P on the Lissajous figure.

Another part 1 of the beam spot 144
Reference numeral 44b irradiates the second optical pattern 114, for example, a cylindrical hologram lens, when the scale 104 is at the reference position. The beam of the reflected light is narrowed in the direction of movement of the scale 104 to form a beam spot 148 that suitably illuminates the second photodetector 126. As a result, the light is sensed by the second photodetector 126, and the reference position signal is detected.

On the other hand, when the scale 104 is out of the reference position, another part 144 of the beam spot 144
b deviates from the second optical pattern 114,
No light is sensed by the second photodetector 126, and no reference position signal is detected.

As described above, the linear encoder 100
Is provided with the second optical pattern 114 and the second detector 126, so that the reference point position of the scale 104 can be detected. Further, by using the cylindrical hologram lens, the reference position of the scale 104 can be detected with high accuracy.

In particular, the light receiving area 140 more preferably has a width smaller than p1 (z1 + z2) / z1. Here, the width is a dimension along the moving direction of the scale 104,
z1 is the length of the main axis of the light beam traveling from the light source 122 to the scale 104, and z2 is the length of the main axis of the light beam traveling from the optical pattern 114 to the light receiving area 140.
In this case, in this case, the reference point position of the scale 104 can be detected with a sensitivity of the period p1 of the optical pattern 112 of the scale 104 or less.

When the thickness of the surface emitting laser 122 is sufficiently smaller than z 1 and z 2, the ratio between z 1 and z 2 becomes constant, so that the diffraction interference pattern 14 projected on the photodetector 124 is obtained.
The period p2 of No. 6 does not change. Further, the diffraction interference pattern 146 projected on the photodetector 124 moves in a direction perpendicular to the moving direction of the scale 104 with respect to changes in z1 and z2, and thus has no influence on the detected position accuracy. Absent.

As can be understood from the above description, the linear encoder of this embodiment is excellent in mass productivity because the surface emitting laser 122 is mounted on the flat substrate 120. The light beam 142 from the light source 122
4 is irradiated almost perpendicularly, which is suitable for miniaturization.
In addition, two different optical patterns 1
Since the scales 12 and 124 are illuminated and different scale information is obtained, they are compact and have high performance.

This embodiment can be modified in various ways. Second optical pattern 114 for reference position detection
Is not limited to the cylindrical hologram lens, and may be any pattern as long as the optical characteristics change at the reference position with respect to the moving direction of the scale 104. Further, the photodetector 126 is not limited to a single light receiving area, and may include a plurality of light receiving areas arranged in parallel. Further, a light receiving area pattern corresponding to the second optical pattern 114 may be provided.

Further, in order to set z1 = z2, for example, by arranging the surface emitting laser 122 so as to be sunk, the height of the emitting surface of the surface emitting laser 122 and the light receiving surface of the photodetector 124 are made uniform. Is also good. Further, in order to increase the effective height of the light receiving surface of the light receiving area, for example, a refractive index member for adjusting an optical distance may be arranged in the optical path.

Hereinafter, some modifications will be described with reference to the drawings.

The first modification relates to the improvement of the light source, and as shown in FIG. The surface emitting laser 150 emits the light beam 142 from the upper surface facing the scale and emits the light beam 152 from the lower surface on the opposite side.

The substrate 120 has a laser mounting portion 154. The laser mounting portion 154 is formed of a metal pattern and is electrically connected to an electrode on the lower surface of the surface emitting laser 150. The laser mounting portion 154 has an opening at a central portion thereof, through which a light beam 152 emitted from the lower surface of the surface emitting laser 150 passes.

The substrate 120 further includes a laser mounting portion 1
The light receiving unit 158 for detecting the intensity of the light beam 152 that has passed through the opening 54 is provided. The light receiving unit 158 outputs a signal corresponding to the intensity of the incident light beam 152.

In the surface emitting laser 150, the light beam 142 emitted from the upper surface and the light beam 1 emitted from the lower surface
The light intensity ratio of 52 is constant. Therefore, the light receiving section 158
The intensity of the light beam 142 emitted from the upper surface of the surface emitting laser 150 is adjusted to a desired intensity by controlling the driving of the surface emitting laser 150, for example, by a processing circuit (not shown) according to the output signal from Can be. Alternatively, control can be performed so that the intensity of the light beam 142 is kept constant even when the environment changes due to a change in temperature or the like. Further, control can be performed so that a light beam having an intensity exceeding a predetermined upper limit value is not emitted.

As described above, the linear encoder according to this modification can control the intensity of the light beam 142 emitted from the surface emitting laser 150 without adding a separate element or element.

The second modification relates to the improvement of the scale, and as shown in FIG.
Are the first optical pattern 112 and the second optical pattern 1
14, an elongated low-reflection or non-reflection region 116 extending in a band along the moving direction of the scale 104 is provided. Stated another way, the scale 104 includes a strip-shaped elongated region having a low reflectance or a region 116 having a reflectance substantially equal to 0 at a portion irradiated with a portion near the main axis of the light beam emitted from the light source. ing.

In such an area 116, the light beam emitted from the light source
At 12, the undesirable phenomenon of rarely being reflected by the optical pattern 114 and re-entering the light source to destabilize the output characteristics of the light source is prevented. Stated another way, the formation of a so-called composite resonator between the light source and the scale is prevented. As a result, the light beam emitted from the light source is stabilized.

The third modification also relates to the improvement of the scale, and as shown in FIG.
Is provided with a band-like low-reflection or non-reflection region 116 extending in the central portion of the transparent substrate 110 in parallel with the movement direction of the scale 104, and a pair of optical patterns 112a and 112b for movement detection located on both sides thereof. Each of the optical patterns 112a and 112b has a scale 1
It extends over substantially the entire scale 104 along the movement direction of the scale 104, and has a reflectance that changes at a constant cycle along the movement direction of the scale 104.

As shown in FIG. 8, the encoder head 102 includes a pair of photodetectors 124a and 124b for detecting reflected light from the respective optical patterns 112a and 112b according to the scale 104. Have. Each of the photodetectors 124a and 124b is
Are provided with a plurality of light receiving areas including first to fourth light receiving area groups, similarly to the photodetector 124 shown in FIG.

In this modification, since the scale 104 has the low-reflection or non-reflection region 116, the formation of a composite resonator between the light source and the scale is prevented,
As a result, the light beam emitted from the light source is stabilized. Further, compared to the configuration of FIG. 1, since it detects a diffraction interference pattern of about twice the amount of light, it has strong resistance to dust, dust, scale scratches and defects, and the like.

The fourth modification also relates to the improvement of the scale, and as shown in FIG.
Is a band-like low-reflection or non-reflection region 116 extending in the central portion of the transparent substrate 110 in parallel with the moving direction of the scale 104, a pair of optical patterns 112 a and 112 b for movement detection located on both sides thereof, and A pair of reference position detecting optical patterns 114a located on both outer sides,
114b. Optical patterns 112a, 11
2b extend substantially along the entire direction of the scale 104 along the moving direction of the scale 104, respectively.
4 has a reflectance that changes at a constant cycle along the moving direction. The optical patterns 114a and 114b each correspond to the scale 104 in the moving direction of the scale 104.
And has a function of condensing light in the movement direction of the scale 104.

As shown in FIG. 10, the encoder head 102 has a pair of photodetectors 124a and 124b for detecting reflected light from the respective optical patterns 112a and 112b, as shown in FIG.
And a pair of photodetectors 126a, 126 for detecting reflected light from the respective optical patterns 114a, 114b.
6b. Each of the photodetectors 124a and 124b has a first to a similar configuration as the photodetector 124 shown in FIG.
A plurality of light receiving areas including a fourth light receiving area group are provided. Further, each of the photodetectors 126a and 126b
Has a single light receiving area, similarly to the photodetector 126 shown in FIG.

In this modification, since the scale 104 has the low-reflection or non-reflection region 116, the formation of a composite resonator between the light source and the scale is prevented,
As a result, the light beam emitted from the light source is stabilized. In addition, the optical patterns 112a and 112b for movement detection, which are desirably illuminated with strong light, are irradiated with relatively strong portions of the light beam, so that there is no need to illuminate with strong light. Optical pattern 114
Since the portions a and 114b are irradiated with a portion where the intensity of the light beam is relatively weak, both high accuracy and high function are achieved.

The fifth modification relates to a photodetector. As shown in FIG. 11, the photodetector 124 for detecting movement includes a first light receiving area group 132 and a second light receiving area group. And a light receiving area group 130B including a third light receiving area group 136 and a fourth light receiving area group 138. The light receiving areas of the first light receiving area group 132 and the light receiving areas of the second light receiving area group 134 are alternately arranged at a pitch of p / 2. Similarly,
The light receiving areas of the third light receiving area group 136 and the light receiving areas of the fourth light receiving area group 138 are also alternately arranged at a pitch of p / 2. Light receiving area group 130A and light receiving area group 130
The two adjacent light receiving areas of B are p2 / 4 + p2 × n (n
Has a natural number) interval.

This photodetector can be manufactured more easily than the photodetector shown in FIG. 2 in which the pitch is p2 / 4 since the pitch between adjacent light receiving areas is p2 / 2. In addition, since the area of each light receiving area can be made large, the S / N of scale movement detection is improved. Further, in response to the requirement of a very small pitch p2, the photodetector shown in FIG. 2 is expected to be difficult to manufacture and to cause a considerable increase in cost.
The photodetector shown in FIG. 11 can be manufactured relatively easily for the same requirements.

The sixth modification relates to a scale, and as shown in FIG. 12, a scale 104 extends substantially all of the scale 104 along the direction in which the scale 104 moves. Pattern 112,
An optical pattern 118 for detecting a reference position, which is present in a partial area in the moving direction of the scale 104. As described above, the optical pattern 112 has a reflectance that changes at a constant period along the moving direction of the scale 104. The optical pattern 118 has a function of reflecting the light applied thereto and condensing the light at one point.
It is composed of a holographic pattern, for example, a hologram lens.

In this modification, the light beam reflected by the reference position detecting optical pattern 118 is condensed at one point. Therefore, even if the parallelism between the encoder head and the scale is slightly reduced, the reference position can be detected. When the scale is at the reference position, the light beam is stably irradiated on the photodetector for detecting the reference position. That is, when the scale is at the reference position, the small-diameter, substantially circular beam spot formed on the light receiving surface of the photodetector for detecting the reference position has an elongated shape with respect to a decrease in the parallelism between the encoder head and the scale. Since the light detector only moves on the light receiving surface along the longitudinal direction, a sufficient amount of light is always applied to the photodetector for detecting the reference position. This relaxes the parallelism required of the encoder head and scale, making it easier to install and assemble, or expanding its application range.

Second Embodiment As shown in FIG. 13, an optical linear encoder 100 according to a second embodiment includes an encoder head 102 including an optical system for detecting movement and an encoder head 102. And a movable scale 104 that can be translated.

The movable scale 104 has an optical pattern 162 for detecting movement of the scale 104 formed on the surface of an optically transparent substrate such as a glass substrate 160. The optical pattern 162 extends over substantially the entire surface of the scale 104, and has a reflectance that changes at a constant cycle along the moving direction of the scale 104.

The encoder head 102 includes a coherent light source 172 that emits coherent light and light detecting means or a light detector 124 for detecting light reflected from the optical pattern 162, both of which are provided. It is held on a substrate 170. The coherent light source 172 is, for example, a surface emitting laser, and is fixed to the substrate 170 by means such as bonding.

The substrate 170 is, for example, a semiconductor substrate, and the photodetector 174 is formed on the semiconductor substrate 170. The photodetector 174 has a plurality of light receiving areas surrounding the surface emitting laser 172 and extending over almost the entire surface of the substrate 170, and the light receiving areas are arranged at a constant pitch along the moving direction of the scale 104. I have. The area around the light source where the light receiving area is not formed is Wspace = p2 × n (n = 1, 2, 3,...) Along the moving direction of the scale.
・ ・) It is desirable to have a length.

As described above, the movement detection optical pattern 1
62 is formed on almost the entire surface of the scale 104, and the photodetector 174 for movement detection is also formed on almost the entire surface of the encoder head 102.
4, the linear encoder 100 has high resistance to dust and dirt on the scale 104, disturbance and scratches of the optical pattern 162, and the like. I have.

Further, the linear encoder 100 is provided with a quarter-wave plate 176 for rotating the polarization plane or the polarization plane of the light beam by 45 degrees on the main axis of the light beam emitted from the surface emitting laser 172. Quarter wave plate 176
May be arranged anywhere on the main axis of the light beam emitted from the surface emitting laser 172. For example, the 波長 wavelength plate 176 is attached to the exit window of the surface emitting laser 172.

The light re-entering the surface emitting laser 172 is emitted from the surface emitting laser 172, reflected by the optical pattern 162 of the scale 104, and returned to the surface emitting laser 172 through the 波長 wavelength plate 176. Since the light has passed twice, it has a polarization plane or polarization plane rotated by 90 degrees with respect to the polarization plane or polarization plane of the light immediately after being emitted from the surface emitting laser 172. Therefore, the re-incident light does not interfere with the light immediately after the emission, and does not affect the emission light of the surface emitting laser 172. Therefore, a stable light beam is emitted from the surface emitting laser 172.

The quarter-wave plate 176 may be provided on the surface of the scale 104. In this case, by replacing the scale of the encoder having no countermeasures against the return light to the surface emitting laser 172 with one having the quarter-wave plate 176, the encoder head can be used as it is, The problem of returning light to the surface emitting laser 172 can be solved.

Third Embodiment As shown in FIG. 14, an optical linear encoder 100 according to a third embodiment includes an encoder head 102 including an optical system for detecting movement and an encoder head 102. And a movable scale 104 that can be translated.

The movable scale 104 includes an optical pattern 202 for detecting the movement of the scale 104, a pair of optical patterns 204 for detecting the reference position of the scale 104, and a pair of optical patterns 206 for monitoring the output of the light source. Both of these optical patterns are formed on the surface of the optically transparent substrate 200. The pair of optical patterns 206 for monitoring the output are arranged on both outer sides of the pair of optical patterns 204 for detecting the reference position.

The movement detecting optical pattern 202 extends along the moving direction of the scale 104 and
It has a reflectivity that changes at a constant cycle along the movement direction of No. 04. The optical pattern 204 for reference position detection is
It is present in some regions with respect to the moving direction of the scale 104 and has a function of condensing light in the moving direction of the scale 104. The output monitoring optical pattern 206 has a high reflectivity and extends along the moving direction of the scale 104.

The encoder head 102 includes a first light source 212 for irradiating a coherent light beam to the movement detection optical pattern 202, a reference position detection optical pattern 204, and an output monitoring optical pattern 206. A second light source 214 for irradiating a light beam, a light detecting means or a photodetector 216 for detecting reflected light from the optical pattern 202 for detecting movement, and a second light source 214 for detecting an optical pattern 204 for detecting a reference position. A pair of light detecting means or light detectors 218 for detecting reflected light and a pair of light detecting means or light detectors 220 for detecting reflected light from the output monitoring optical pattern 206 are provided. . These elements are both held on the substrate 210.

The first light source 212 and the second light source 214 are, for example, the same surface emitting lasers, and both are fixed to the substrate 210 by means such as bonding. Substrate 2
Reference numeral 10 denotes a semiconductor substrate, for example, and photodetectors 216 and 21
8, 220 are semiconductor substrates 210 by a semiconductor process.
Is formed.

The movement detecting photodetector 216 has a plurality of light receiving areas arranged at a constant pitch along the moving direction of the scale 104, and these light receiving areas surround the surface emitting laser 212. It has spread. Each of the pair of photodetectors 218 for reference position detection has a single elongated light receiving area in a direction orthogonal to the moving direction of the scale 104, and these pair of light receiving areas are orthogonal to the moving direction of the scale 104. With respect to the direction in which the light is emitted, the laser light is disposed on both sides of the surface emitting laser 214. Each of the pair of photo detectors 220 for output monitoring has a single relatively large rectangular light receiving area, and the pair of light receiving areas is used to detect a reference position in a direction orthogonal to the moving direction of the scale 104. Are arranged on both outer sides of a pair of photodetectors 218.

The light beam emitted from the surface emitting laser 212 is applied to the optical pattern 2 for detecting the movement of the scale 104.
02, and the diffraction interference pattern formed by the optical pattern 202 is applied to the photodetector 216 for movement detection. This diffraction interference pattern is formed by the entire predetermined region not including the main axis of the light beam emitted from the surface emitting laser 212, and most of the region is detected by the movement detection photodetector 216. The linear encoder 100 has high resistance to dust and dirt adhering to the scale 104, disturbance and scratches of the optical pattern 202, and the like.

A part of the light beam emitted from the surface emitting laser 212 always irradiates the optical pattern 206 for output monitoring, and the other part is the scale 104.
Is irradiated on the reference position detecting optical pattern 204 of the scale 104 when is at the reference position.

The light reflected by the output monitoring optical pattern 206 is applied to an output monitoring photodetector 220, and a signal reflecting the output of the surface emitting laser 214 is output from the photodetector 220. . By controlling the driving of the surface emitting laser 214 in accordance with the signal from the photodetector 220, the light beam emitted from the surface emitting laser 212 is stabilized.

When the scale 104 is at the reference position, the light reflected by the reference position optical pattern 204 is narrowed in the direction parallel to the direction in which the scale 104 moves, and the light detected by the reference position detection is detected. The scale 104 is illuminated, and it is detected that the scale 104 is at the reference position according to the output of the photodetector 218.

Fourth Embodiment As shown in FIG. 15, an optical linear encoder 100 according to a fourth embodiment includes an encoder head 102 including an optical system for detecting movement and an encoder head 102. And a movable scale 104 that can be translated.

As shown in FIG. 16, the movable scale 1
Reference numeral 04 includes an optical pattern 242 for movement detection, an optical pattern 244 having the same structure as this, and an optical pattern 246 for reference position detection, formed on the surface of the optically transparent substrate 240. These optical patterns 24
2, 244 and 246 are arranged along the moving direction of the scale 104, and the optical pattern 246 is the optical pattern 2
42 and the optical pattern 244.

The optical pattern 242 has a reflectance that changes at a constant period p1 along the moving direction of the scale 104. The optical pattern 246 has a function of condensing light in the movement direction of the scale 104, and is, for example, a holographic pattern such as a cylindrical hologram lens.

As shown in FIG. 15, the encoder head 102 includes a light source 252 that emits coherent light, a light detecting means or a light detector 254 for detecting movement of the scale 104, and a reference position detection for the scale 104. Light detecting means or a light detector 256. Light source 25
2, the photodetector 254 and the photodetector 256
The light source 252 is located between the light detector 254 and the light detector 256.

For example, the coherent light source 252 is a single surface emitting laser, the photodetector 254 and the photodetector 256 are formed integrally with the semiconductor substrate 250, and the surface emitting laser 252 is attached to the semiconductor substrate 250 by bonding or the like. It is fixed to. That is, the light source 252, the light detector 254, and the light detector 256 are provided on the substrate 250 in a hybrid manner.

The photodetector 254 has a plurality of light receiving areas elongated in a direction orthogonal to the moving direction of the scale 104, and these light receiving areas are arranged along the moving direction of the scale 104 and have a period p 1 of the optical pattern 242. Are arranged at a constant pitch p2 which is about twice as large as Further, the photodetector 256 has a single light receiving area which is elongated in a direction orthogonal to the direction in which the scale 104 moves.

The light beam emitted from the surface emitting laser 252 is applied to the scale 104, and the diffraction interference pattern formed by the optical pattern 242 for movement detection is projected on the photodetector 254 for movement detection. Also,
When the scale 104 is at the reference position, the light beam reflected by the reference position detection optical pattern 246 is narrowed in the movement direction of the scale 104 and is irradiated to the reference position detection photodetector 256. You. The optical pattern 244 has the same structure as the optical pattern 242 for movement detection, but is not used for detecting movement of the scale 104, but is used for detecting excessive movement of the scale 104 and the like.

The light detector 254 for detecting movement has a plurality of light receiving areas including first to fourth light receiving area groups, similarly to the light detector 124 shown in FIG. Therefore, an A-phase signal and a B-phase signal can be obtained based on the output of each light receiving area group, and the movement of the scale 104 can be detected based on these signals.

In this embodiment, the encoder head 1
02 indicates that the single surface emitting laser 252 is
Semiconductor substrate 25 on which photodetector 256 and photodetector 256 are integrally formed
0, but the configuration of the encoder head 102 is not limited to this.

For example, as shown in FIG. 17, the encoder head 102 has a monolithic structure in which a surface emitting laser 252, a photodetector 254, and a photodetector 256 are integrally integrated on a semiconductor substrate 250 by a semiconductor manufacturing process. There may be. Alternatively, as shown in FIG. 18, the encoder head 102 includes a single surface-emitting laser 252, a single photodetector 254, and a single photodetector 2
56 may be a hybrid configuration attached to the substrate 250.

In the first to fourth embodiments described above, the optical pattern of the scale 104 may be variously modified. Modifications of the optical pattern of the scale 104 are shown in FIGS. Of course, in applying the optical patterns of these modified examples, the layout of the light detecting means or the light detector of the encoder head 102 should be changed according to the layout of the optical patterns. Further, in the application of the scale 104 shown in FIGS. 19 and 20, the encoder head 102 is used to prevent interference between light emitted from the light source and light returned to the light source.
It is preferable to provide a / 4 wavelength plate.

The scale 104 shown in FIG. 19 includes an optical pattern 262 for detecting a movement, an optical pattern 264 for detecting a reference position, and an optical pattern 266 for monitoring an output. 2
60 are formed. Optical pattern 26 for movement detection
2 extends along the moving direction of the scale 104,
It has a reflectance that changes at a constant cycle along the moving direction of the scale 104. The optical pattern 264 for reference position detection exists in a part of the area in the moving direction of the scale 104 and has a function of condensing light in the moving direction of the scale 104. The optical pattern 206 for output monitoring has a constant high reflectance,
It extends like a band along the moving direction of the scale 104.
The movement detection optical pattern 262 extends over almost half the surface of the scale 104, and the movement detection optical pattern 26
2, the optical pattern 264 for detecting the reference position, and the optical pattern 206 for monitoring the output are arranged in a direction orthogonal to the moving direction of the scale 104.

The scale 104 shown in FIG. 20 includes an optical pattern 262 for detecting movement and an optical pattern 266 for monitoring output. The movement detection optical pattern 262 extends along the movement direction of the scale 104 and has a reflectance that changes at a constant cycle along the movement direction of the scale 104. The output monitoring optical pattern 206 has a constant high reflectance, and extends in a band along the moving direction of the scale 104. The movement detection optical pattern 262 extends over almost half the surface of the scale 104, and the output monitoring optical pattern 20.
6 extends over substantially the entire other half of the scale 104.

The scale 104 shown in FIG. 21 has an optical pattern 262 for detecting movement and a pair of optical patterns 264 for detecting a reference position. The movement detection optical pattern 262 extends along the movement direction of the scale 104 and has a reflectance that changes at a constant cycle along the movement direction of the scale 104. The optical pattern 264 for reference position detection exists in a part of the area in the moving direction of the scale 104 and has a function of condensing light in the moving direction of the scale 104. The optical pattern 262 for movement detection extends to the center of the scale 104, and the optical patterns 264 for reference position detection are located on both sides of the scale 104.

The scale 104 shown in FIG. 22 has an optical pattern 262 for movement detection and an optical pattern 266 for output monitoring. The movement detection optical pattern 262 extends along the movement direction of the scale 104 and has a reflectance that changes at a constant cycle along the movement direction of the scale 104. The output monitoring optical pattern 206 has a constant high reflectance, and extends in a band along the moving direction of the scale 104. The movement detection optical pattern 262 extends to the center of the scale 104, and the output monitoring optical pattern 206.
Are located on both sides of the scale 104.

Further, the photodetector for detecting the movement may be variously modified. Modifications of the photodetector for detecting movement are shown in FIGS.
As shown in FIG.

The photodetector 2 for movement detection shown in FIG.
Reference numeral 80 includes two types of light receiving area groups, that is, a first light receiving area group 282 and a second light receiving area group 284.
First light receiving area group 282 and second light receiving area group 284
Are alternately arranged along the moving direction of the scale. Each of the first light receiving area group 282 and the second light receiving area group 284 has four light receiving areas arranged at a constant pitch p2. Two adjacent light receiving areas of the first light receiving area group 282 and the second light receiving area group 284 are p
It has an interval of 2/4 × n (n is a natural number).

The photodetector 2 for movement detection shown in FIG.
80 includes four types of light receiving area groups, that is, a first light receiving area group 282, a second light receiving area group 284, a third light receiving area group 286, and a fourth light receiving area group 288. First light receiving area group 282 and second light receiving area group 2
84, the third light receiving area group 286, and the fourth light receiving area group 288 are alternately arranged along the moving direction of the scale. First light receiving area group 282 and second light receiving area group 2
84, the third light receiving area group 286, and the fourth light receiving area group 288 each have four light receiving areas arranged at a constant pitch p2. Two adjacent light receiving areas of the two adjacent light receiving area groups have an interval of p2 / 4 × n (n is a natural number).

The photodetector 2 for movement detection shown in FIG.
Reference numeral 80 denotes three types of light receiving area groups, that is, a first light receiving area group 282, a second light receiving area group 284, a third light receiving area group 286, and a four-phase signal from signals obtained from the three types of light receiving area groups. And a signal processing circuit 290 that produces The first light receiving area group 282, the second light receiving area group 284, and the third light receiving area group 286 are alternately arranged along the moving direction of the scale. First light receiving area group 2
Each of 82, the second light receiving area group 284, and the third light receiving area group 286 has four light receiving areas arranged at a constant pitch p2. Two adjacent light receiving areas of the two adjacent light receiving area groups have an interval of p2 / 4 × n (n is a natural number).

Although the above-described first to fourth embodiments are all reflective linear encoders, the application of the present invention is not limited to this, and the present invention is applied to transmissive linear encoders. You may.

Fifth Embodiment A fifth embodiment relates to a reflection type optical rotary encoder, which will be described with reference to FIGS.

As shown in FIG. 26, an optical rotary encoder 300 according to the present embodiment has an encoder head 302 including an optical system for detecting movement, and is rotatable or rotatable with respect to the encoder head 302. And a rotary scale 304.

The rotary scale 304 is a scale 3 formed on the surface of a circular optically transparent substrate 310.
An optical pattern 04 or a diffraction grating pattern 312 for detecting rotation is provided. This diffraction grating pattern 312
As shown in FIG. 27, has a plurality of fan-shaped reflecting portions arranged radially, and the reflecting portions are arranged with a fan-shaped gap having the same size as the fan-shaped reflecting portions. In other words,
The fan-shaped reflecting portions and the non-reflecting portions having the same size are alternately arranged along the circumference, and the ratio of the area of the reflecting portion to the area of the non-reflecting portion is 1: 1.

Further, the rotary scale 304 is
As shown in FIG. 7, a low-reflection region 314 is provided at the center of the transparent substrate 310, that is, near the center of rotation. In other words, the scale 304 includes a region where the reflectivity is low or a region where the reflectivity is almost equal to 0 in a portion where the portion near the main axis of the light beam emitted from the light source is irradiated.
14 is provided.

The encoder head 302 includes a light source that emits coherent light, that is, a coherent light source 322, and light detecting means or light detector 324 for detecting rotation of the scale. The light detector 324 includes a plurality of light receiving areas 33.
0, in other words, a light receiving element such as a photodiode is provided. These light receiving areas 330 are light sources 3
22 are arranged at a constant angular pitch on a circumference around the center 22.

For example, the coherent light source 322 is, for example, a single surface emitting laser, and the photodetector 324 is formed on a semiconductor substrate 320 integrally formed by a semiconductor manufacturing process.
It is fixed to the substrate 320 by means such as adhesion. That is, the light source 322 and the photodetectors 324 and 326 are
20 is provided in a hybrid. Since the surface emitting laser 322 is fixed to the flat substrate 320, it can be easily attached.

The encoder head 302 and the rotary scale 304 are arranged parallel to each other at a predetermined interval so that the rotation axis of the rotary scale 304 and the main axis 328 of the light beam emitted from the encoder head 302 substantially coincide with each other. ing. Therefore, the light beam emitted from the surface emitting laser 322 irradiates the surface of the scale 304 substantially perpendicularly. That is, the main axis 328 of the light beam emitted from the surface emitting laser 322 is substantially perpendicular to the rotary scale 304.

The encoder head 302 preferably employs the configuration shown in FIG. That is,
The surface emitting laser 322 is a two-sided surface emitting laser, and the encoder head 302 is
The light receiving unit further includes a light receiving unit that detects a light beam emitted from the lower surface of the laser light source 22. The intensity of the light beam emitted from the surface emitting laser is controlled by a processing circuit (not shown) according to the output from the light receiving unit.

On the surface of the rotary scale 304, light incident on the circumference 342 of radius r1 is irradiated on the surface of the encoder head 302 on the circumference 344 of radius r2. Here, the radius r1 and the radius r2 are
The relationship r2 = r1 (z1 + z2) / z1 is satisfied, where z1 is the distance between the surface emitting laser 322 and the scale 304, and z2 is the distance between the scale 304 and the photodetector 324.

The light receiving area 330 on the encoder head 302 has a relatively long dimension in the radial direction with the surface emitting laser 322 substantially at the center. Preferably, the light receiving area 330 of the photodetector 324 has a distance rmin from the center of rotation of the rotary scale 304 to the inside of the diffraction grating pattern 312 and a distance rmax to the outside of the diffraction grating pattern 312 from the surface emitting laser 322 at rmin (z1 + z2) /. z1 and rmax (z1 +
z2) / z1. Such a light receiving area 33
0 can detect any light incident on the diffraction grating pattern 312. It is more preferable that the light receiving area 330 extends beyond this range. Even when z1 (= z2) is widened, any light incident on the diffraction grating pattern 312 can be detected.

The light beam having a predetermined spread emitted from the surface emitting laser 322 is
4 perpendicularly. A portion near the main axis of the light beam illuminates the low-reflection region 314 formed near the center of the rotary scale 304, and a portion outside the same illuminates the optical pattern 312 located outside the low-reflection region 314. I do.

The light beam illuminating the low-reflection region 314 is absorbed by the light beam and hardly returns to the surface-emitting laser 322. As a result, the surface emitting laser 3
The light beam emitted from the rotary scale 30 is
By re-entering the surface-emitting laser 322 after being reflected by the surface of the laser light source 4, the occurrence of an undesirable phenomenon that the output characteristics of the light source become unstable is prevented. In other words,
The formation of a so-called composite resonator between the surface emitting laser 322 and the scale 304 is prevented. as a result,
The light beam emitted from the surface emitting laser 322 is stabilized.

As described above, the rotary scale 30
As shown in FIG. 27, the diffraction grating pattern 312 of No. 4 has a large number of fan-shaped reflecting portions arranged radially, so that the pitch of the diffraction grating pattern 312 differs in the radial direction of the rotary scale 304. ing. That is,
Since the same number of reflective portions and non-reflective portions are present on the circumference of an arbitrary radius on the diffraction grating pattern 312, the pitch p1 of the diffraction grating pattern continuously changes in the radial direction of the rotary scale 304.

Therefore, the light beam of the portion illuminating the optical pattern 312 is reflected and diffracted by the optical pattern 312, and the diffraction interference pattern formed by the range where the pitch p 1 almost satisfies the expression (1) is used as the light detector 324. Projected above. The diffraction interference pattern has radially extending interference fringes. In other words, the diffraction interference pattern has a light and dark pattern along the circumference. The light / dark pattern rotates in accordance with the rotation of the rotary scale 304.

In FIG. 26, assuming that the thickness of the surface emitting laser 322 is sufficiently smaller than the distance z1 between the surface emitting laser 322 and the scale 304 and the distance z2 between the scale 304 and the photodetector 324, z1 = z2. Can be approximated,
From equation (2), p2 = 2p1, and the encoder head 30
The light and dark pattern projected on the second light receiving surface has a pitch p2 which is about twice the pitch p1 of the diffraction grating pattern of the rotary scale 304.

Some examples of the encoder head 302 are shown in FIGS. In any encoder head 302, the light receiving area 330 includes a first light receiving area group 332, a second light receiving area group 334, a third light receiving area group 336, and a fourth light receiving area group 338, and is the same. The light receiving areas of the light receiving area group are electrically connected to each other, the first light receiving area group 332 receives the A ⁺ signal, the second light receiving area group 334 receives the A ⁻ signal, and the third light receiving area group 336 receives the A ⁻ signal. The B ⁺ signal is transmitted to the fourth light receiving area group 3
38 B ^- outputs the signal.

[0127] These signals are processed by a (not shown) signal processing circuit, A ⁺ signal and A ^- A by the subtraction of the signal
Phase signal is generated, B ⁺ signal and B ^- B by the subtraction of the signal
A phase signal is generated. The signal processing circuit may be formed on the semiconductor substrate 320, for example, like the photodetector 324. Further, based on the Sage figure obtained from the A-phase signal and the B-phase signal, the rotation amount and the rotation direction of the scale can be accurately obtained.

An encoder head 30 shown in FIG.
In 2, the light receiving areas included in the first light receiving area group 332, the second light receiving area group 334, the third light receiving area group 336, and the fourth light receiving area group 338 are respectively sequentially arranged on the circumference. ing. According to this layout, A ⁺
The signal, the A ^- signal, the B ⁺ signal, and the B ^- signal are detected over the entire circumference.
A stable signal can be detected even when the diffraction grating 04 has a defect or a scratch, or has a non-uniform reflectance.

An encoder head 30 shown in FIG.
In No. 2, light receiving areas belonging to the same light receiving area group are arranged adjacently. According to this layout, the photodetector can be miniaturized and electric wiring can be minimized. Further, the size of the light receiving area can be made ideal, and the signal strength and the like can be sufficiently obtained.

The encoder head 30 shown in FIG.
In 2, the same light receiving area group is further divided into three small groups, and the small groups of the first to fourth light receiving area groups are sequentially arranged along the circumference. That is, the small groups of the light receiving area groups are arranged at an angular interval of about 120 degrees. According to this layout, it is possible to minimize the influence of non-uniformity of defects, scratches, reflectance, and the like of the diffraction grating of the scale 304 without complicating the electric wiring.

In the present embodiment, the receiving detector detects four different phases of the diffraction interference pattern.
If necessary, only one phase, or two or three different phases may be detected, or more phases may be detected.

According to the present embodiment, it is hardly affected by scratches and dust, the adjustment of the distance between the scale and the light source or the photodetector is easy, and no expensive parts or special assembly is required for the assembly. , An ultra-compact, high-performance rotary encoder is provided.

Sixth Embodiment A sixth embodiment is a reflection type optical rotary encoder, which will be described with reference to FIG. The sixth embodiment is similar to the fifth embodiment, and members denoted by the same reference numerals denote equivalent members, and a detailed description thereof will be omitted in the following description.

As shown in FIG. 31, an optical rotary encoder 300 according to the present embodiment includes an encoder head 302 including an optical system for detecting movement, and a rotatable or rotatable with respect to the encoder head 302. And a rotary scale 304.

The rotary scale 304 is a scale 3 formed on the surface of a circular optically transparent substrate 310.
An optical pattern 04 or a diffraction grating pattern 312 for detecting rotation is provided. The rotary scale 304 of the present embodiment is different from the rotary scale of the fifth embodiment in that the low reflection area 31 shown in FIG.
4 is not provided near the center of rotation.

The encoder head 302 includes a light source that emits coherent light, that is, a coherent light source 322, and light detecting means or a light detector 324 for detecting rotation of the scale. The photodetector 324 includes a plurality of light receiving areas 330 arranged at a constant angular pitch on a circumference centered on the light source 322.

For example, the coherent light source 322 is, for example, a single-sided surface-emitting single-sided laser, and the photodetector 324 is fixed to the semiconductor substrate 320 integrally formed by a semiconductor manufacturing process by means of bonding or the like. Have been.

The encoder head 302 and the rotary scale 304 are arranged parallel to each other at a predetermined interval so that the rotation axis of the rotary scale 304 and the main axis 328 of the light beam emitted from the encoder head 302 substantially coincide with each other. ing.

The rotary encoder 300 further includes a quarter-wave plate 340 for rotating the polarization plane or the polarization plane of the light beam by 45 degrees on the main axis of the light beam emitted from the surface emitting laser 322. 1/4 wavelength plate 3
40 may be arranged anywhere on the main axis of the light beam emitted from the surface emitting laser 322. 1/4 wavelength plate 34
0 is attached to the exit window of the surface emitting laser 322, for example.

The re-incident light to the surface emitting laser 322 is 1
Since it has passed through the quarter-wave plate 340 twice, it has a polarization plane or polarization plane rotated by 90 degrees with respect to the polarization plane or polarization plane of the light immediately after being emitted from the surface emitting laser 322. Therefore, the re-incident light does not interfere with the light immediately after the emission, and does not affect the emission light of the surface emitting laser 322. Therefore, a stable light beam is emitted from the surface emitting laser 322.

The quarter-wave plate 340 may be provided on the surface of the scale 304. In this case, by replacing the scale of the encoder having no countermeasures against the return light to the surface emitting laser 322 with one having the quarter-wave plate 340, the encoder head can be used as it is, The problem of the return light to the surface emitting laser can be solved.

According to the present embodiment, there is provided an optical rotary encoder having a stable light source which is not affected by return light without affecting the size and performance of the encoder head.

Although some embodiments have been specifically described with reference to the drawings, the present invention is not limited to the above-described embodiments, and may be carried out without departing from the scope of the invention. Including all implementations.

The optical encoder of the present invention can be summarized as follows.

1. A movable scale on which an optical pattern of a predetermined period is formed, a coherent light source that irradiates the optical pattern surface with a light beam of a predetermined shape substantially vertically, and receives a light beam from the light source reflected by the optical pattern. And a light detecting means for detecting a diffraction pattern generated on the light receiving surface by the optical pattern.

[0146] 2. 2. The optical linear encoder according to claim 1, wherein the optical pattern is formed on the movable scale in a multiple number.

[0147] 3. 3. The optical linear encoder according to claim 2, wherein the plurality of optical patterns are all optical patterns having the same period.

4. 3. The optical linear encoder according to claim 2, wherein the plurality of optical patterns include optical patterns having different periods.

5. The optical linear encoder according to any one of claims 1 to 4, wherein a holographic pattern having a function of reflecting and condensing a light beam is formed on the movable scale.

6. 6. The optical linear encoder according to claim 5, wherein the holographic pattern is used for detecting a reference position.

7. The optical linear encoder according to any one of claims 1 to 6, further comprising a unit configured to suppress the light beam reflected by the movable scale from returning to the light source.

8. 8. The optical linear encoder according to claim 7, wherein a reflectance of the scale surface at a portion where a main axis of the light beam intersects the scale surface is lower than that of the optical pattern portion.

9. Between the light source and the scale surface,
The optical linear encoder according to claim 7, further comprising means for rotating the polarization plane by 90 degrees.

10. The means for rotating the polarization plane is 1 /
Item 10. The optical linear encoder according to Item 9, wherein the optical linear encoder is a four-wavelength plate.

11. The optical linear encoder according to any one of claims 1 to 10, wherein the light detection means includes a plurality of light receiving areas formed on the same base slope.

12. The length of the main axis of the light beam from the coherent light source to the optical pattern is z1, the length of the main axis of the light beam from the optical pattern to the light receiving surface of the light detection means is z2, Pitch to p
Assuming that 1 and n are natural numbers, the light receiving area of the light detecting means has a light receiving area at a position of approximately np1 (z1 + z2) / z1 in a pitch direction of a predetermined portion of the diffraction pattern formed on the light receiving surface. Item 12. The optical linear encoder according to item 11, wherein the optical linear encoder is constituted by a light receiving area group.

13. 13. The optical linear encoder according to any one of claims 1 to 12, wherein the light source and the light detecting means are provided on a same substrate in a hybrid or monolithic manner.

14. The first light source is mounted on a substrate on which the photodetector is formed.
Item 13. The optical linear encoder according to any one of Items 12 to 12.

15. Item 15: The coherent light source is a surface emitting laser.
The optical linear encoder described in (1).

16. The coherent light source emits a light beam also from a surface opposite to a surface from which the light beam is emitted toward the optical pattern, and an intensity detecting means for receiving the latter light beam and detecting the intensity. The optical device according to any one of claims 1 to 15, further comprising: a unit that controls a light beam intensity of the coherent light source using a detection result of the intensity detection unit. Type linear encoder.

17. A rotatable scale having an optical pattern with a predetermined period formed in the circumferential direction of rotation, a coherent light source that irradiates the optical pattern surface with a light beam of a predetermined shape substantially vertically, and via the optical pattern An optical rotary encoder for receiving a light beam from the light source and detecting a diffraction pattern generated on a light receiving surface by the optical pattern.

18. 18. The optical rotary encoder according to claim 17, wherein the coherent light source is located on a rotation axis.

19. Item 17 or Item 18, wherein the optical rotary encoder is of a reflection type.
An optical rotary encoder according to the item.

20. The seventeenth feature is that the diffraction pattern is generated on the light receiving surface in a shape of a full circle.
Item 20. The optical rotary encoder according to any one of items 19 to 19.

21. 21. The optical rotary encoder according to any one of claims 17 to 20, further comprising means for suppressing the light beam reflected by the scale from returning to the light source.

22. The reflectance of the scale surface at the portion where the main axis of the light beam intersects the scale surface,
A first portion which is lower than the optical pattern portion.
Item 22. The optical rotary encoder according to any one of Items 7 to 21.

23. 22. The optical rotary encoder according to any one of claims 17 to 21, further comprising means for rotating the plane of polarization by 90 degrees between the light source and the scale surface.

24. The means for rotating the polarization plane is 1 /
Item 24. The optical rotary encoder according to Item 23, which is a four-wave plate.

25. A movable scale on which an optical pattern of a predetermined period is formed, a coherent light source for irradiating a light beam of a predetermined shape to the optical pattern surface, and a light beam from the light source passing through the optical pattern; Optical detection means for detecting a diffraction pattern generated on a light receiving surface by a pattern, wherein the light detection means is configured not to receive light of a main axis of the light beam. encoder.

26. A coherent light source that emits a light beam having a predetermined shape, and a predetermined period of optics that are relatively displaced across the light beam emitted from the coherent light source and generate a diffraction interference pattern with the light beam A scale on which a pattern is formed, and a photodetector for detecting a predetermined portion of a diffraction interference pattern generated by the optical pattern; and a main axis of a light beam directed from the coherent light source to the optical pattern formed on the scale. The length of z
1, the length of the main axis of the light beam from the optical pattern formed on the scale to the light receiving area of the photodetector is z2, and the pitch of a predetermined portion of the optical pattern formed on the scale is p1, n Is a natural number, the light receiving area of the photodetector is substantially np in a pitch direction of a predetermined portion of the diffraction interference pattern formed on the light receiving area.
An optical linear encoder having a light intensity detecting means including a light receiving area group having a light receiving area at a position of 1 (z1 + z2) / z1, wherein the light receiving area group of the photodetector is formed on the light receiving area. The optical linear encoder according to claim 1, wherein the optical interference does not have effective light detection sensitivity or is shielded from light near the main axis of the light beam with respect to the diffraction interference pattern.

27. 27. The optical linear encoder according to claim 26, wherein a main axis of a light beam emitted from the light source is incident substantially perpendicular to a pattern surface of the scale.

28. The predetermined area on the scale where the main axis of the light beam emitted from the light source is irradiated is a low reflection area configured to reduce the intensity of reflected light of the light beam emitted from the light source. Features,
Item 28. The optical linear encoder according to Item 27.

29. The scale has a plurality of optical patterns, and a predetermined region of a light beam emitted from the coherent light source is irradiated on a plurality of optical patterns formed on the scale, and reflected light by the plurality of optical patterns is provided. 28. The optical linear encoder according to paragraph 26 or 27, comprising a plurality of photodetectors each receiving a predetermined portion of transmitted light or diffracted light.

30. The predetermined region of the optical pattern of the scale having the predetermined period has at least one optical pattern different from the predetermined period, and the first predetermined region of the light beam emitted from the light source is the optical region of the scale. A light detector that enters through a pattern, and another light detector in which a predetermined area different from the first predetermined area of the light beam enters through an optical pattern of the scale. Item 28. The optical linear encoder according to Item 26 or Item 27.

31. 31. The optical linear encoder according to claim 29, wherein the plurality of photodetectors are a plurality of light receiving areas formed on the same substrate.

32. The light source is hybridly or monolithically integrated on the same substrate as the photodetector,
Item 26 to Item 3 wherein the light source is a coherent light source.
An optical linear encoder according to any one of the preceding claims.

33. 33. The optical linear encoder according to claim 32, wherein the coherent light source is a surface emitting laser.

34. The light receiving area group of the photodetector has at least first and second two light receiving area groups in a moving direction of the scale, and detects a first phase region of a diffraction interference pattern by an optical pattern on the scale. 34. Any one of the paragraphs 26 to 33, comprising: a first light receiving area group; and a second light receiving area group for detecting a second phase area different from the first phase area. The optical linear encoder described in (1).

35. The light receiving area group of the photodetector has first to fourth four light receiving area groups in the moving direction of the scale in order, and a first phase region of a diffraction interference pattern formed by an optical pattern on the scale. A first light receiving area group for detecting the second phase area different from the first phase area, and a third light area different from the first and second phase areas. A third light receiving area group for detecting a phase region of the first, the second, the third phase region and a fourth light receiving area group for detecting a different fourth phase region, characterized by having a Item 34. The optical linear encoder according to Item 34, wherein

36. The surface emitting laser can emit a light beam forward and backward, and a light output measurement light receiving area is provided on a predetermined portion of the photodetector where the surface emitting laser is disposed, and the light is emitted forward from the light source. The light beam to be irradiated on the scale, characterized in that the light beam emitted backward from the light source is arranged so as to be able to enter the light output measuring light receiving area on the photodetector, wherein The described optical linear encoder.

37. The output of the surface-emitting laser can be controlled by the output intensity of a light beam that is incident on the light-output measurement light-receiving area of the photodetector and that is emitted behind the surface-emitting laser. 41. The optical linear encoder according to paragraph 36, wherein

38. At least one of the plurality of optical patterns of the scale has a predetermined area of the light beam emitted from the light source, and is a cylindrical hologram lens having a light condensing property in a moving direction of the scale. Item 30. The optical linear encoder according to Item 29 or 30, wherein

39. 31. The optical linear encoder according to claim 29, wherein at least one of the plurality of optical patterns of the scale is a hologram lens.

40. At least one of the light receiving areas of the photodetector for detecting the light beam condensed by the hologram lens has a width in the moving direction of the scale, p.
Item 39. The optical linear encoder according to Item 38 or 39, wherein the optical linear encoder is shorter than 1 (z1 + z2) / z1.

41. The angle between the plane of polarization of the light beam emitted from the coherent light source and the plane of polarization of the light beam emitted from the coherent light source toward the light source via the pattern surface of the scale, 28. The optical device according to claim 27, wherein an optical element having an angle of about 90 degrees near the exit window of the coherent light source is provided on a main axis of a light beam emitted from the coherent light source to the scale. Optical linear encoder.

42. 42. The optical linear encoder according to claim 41, wherein the optical element is a quarter-wave plate.

43. Relative to the photodetector, rotatable, at least reflection, transmission, a rotary scale formed so that optical properties such as diffraction periodically change, and a light source for irradiating this rotary scale, A light detector having a light receiving area for receiving a predetermined area of reflected light from the rotary scale, transmitted light or diffracted light, and a light-dark pattern by reflected light from the rotary scale, transmitted light or diffracted light. An optical rotary encoder for detecting light by a light receiving area of the photodetector, wherein the light source is disposed substantially on an extension of a rotation axis of the rotary scale.

44. 44. The optical rotary encoder according to claim 43, wherein a main axis of a light beam emitted from the light source is substantially perpendicularly incident near a rotation center of the rotary scale.

45. The light source is a coherent light source that emits a light beam having a predetermined shape, and the rotary scale generates a diffraction interference pattern by a light beam emitted from the coherent light source. On a rotary scale having a predetermined radius r1,
The photodetector is an optical rotary encoder that is a photodetector that receives a predetermined portion of the diffraction interference pattern, wherein the distance between the coherent light source and the pattern of the rotary scale is z1, the pattern of the rotary scale is The distance between the surface and the light receiving area of the light detector is z2, and the light receiving area of the light detector is formed near the circumference having a radius r2 determined by radius r2 = r1 (z1 + z2) / z1, 45. The optical rotary encoder according to claim 44, further comprising a light intensity detecting unit configured by a light receiving area group left of the light receiving area at the angular period position of (1).

46. The optical rotary encoder according to claim 44, further comprising a low-reflection region configured to reduce a reflected light intensity of a light beam emitted from the light source at a central portion of the rotary scale.

47. 45. The light source according to claim 44, wherein the light source is a coherent light source capable of emitting a light beam having a predetermined shape, which is integrally formed in a hybrid or monolithic manner on the same substrate as the photodetector. Optical rotary encoder.

48. The optical rotary encoder according to claim 47, wherein the coherent light source is a surface emitting laser.

49. 48. The optical rotary encoder according to claim 47, wherein the light receiving area groups of the photodetectors are arranged at predetermined intervals on a circumference substantially centered on the surface emitting laser light source.

50. The light receiving area group of the photodetector has at least a first and a second
A first light receiving area group that has two light receiving area groups and detects a first phase area of a diffraction interference pattern by the optical pattern on the scale, and a second phase area different from the first phase area. Any one of paragraphs 44 to 47 having a second light receiving area group to be detected.
Optical rotary encoder according to any one of the above.

51. The light receiving area group of the photodetector includes first to fourth four in the rotation direction of the rotary scale in order.
A first light receiving area group that has two light receiving area groups and detects a first phase area of a diffraction interference pattern formed by the optical pattern on the scale, and a second light area different from the first phase area. A second light receiving area group for detecting a phase region, the third light receiving area group for detecting a third phase region different from the first and second phase regions, and the first, second, and third And a fourth light receiving area group for detecting a fourth phase region different from the fourth phase region.
Item 7. The optical rotary encoder according to item 0.

52. The surface emitting laser can emit a light beam forward and backward, and a light receiving area for light output measurement is provided at a predetermined portion on the photodetector where the light source is arranged, and is emitted forward from the light source. 49. The method according to claim 48, wherein a light beam is applied to the rotary scale, and a light beam emitted backward from the light source is arranged so as to be able to be incident on a light output measuring light receiving area on the photodetector. Optical rotary encoder.

53. The output of the surface-emitting laser can be controlled by the output intensity of a light beam that is incident on the light-output measurement light-receiving area of the photodetector and that is emitted behind the surface-emitting laser. 53. The optical rotary encoder according to paragraph 52.

54. The angle formed between the plane of polarization of the light beam emitted from the coherent light source and the plane of polarization of the light beam emitted from the light source toward the light source via the pattern surface of the scale, 45. The optical rotary encoder according to claim 44, wherein an optical element having an angle of about 90 degrees near the exit window is provided on a main axis of a light beam emitted from the coherent light source to the scale. .

55. The optical rotary encoder according to claim 54, wherein the optical element is a quarter-wave plate.

[0200]

According to the present invention, there is provided an optical encoder in which a light source is arranged in parallel with a scale together with a photodetector. Thereby, the light source and the photodetector can be arranged close to each other, and the assembling thereof can be easily performed. As a result, a low cost, small optical encoder is provided.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of an optical linear encoder according to a first embodiment of the present invention.

FIG. 2 is a plan view of the photodetector for movement detection shown in FIG.

FIG. 3 is a plan view of a photodetector for detecting a reference position shown in FIG. 1;

FIG. 4A shows an A-phase signal and a B-phase signal obtained by a movement detecting photodetector, and FIG. 4B shows a Lissajous figure obtained based on the A-phase signal and the B-phase signal. I have.

FIG. 5 shows a light source and a mounting portion thereof in a first modified example of the first embodiment.

FIG. 6 shows a configuration of a movable scale according to a second modification of the first embodiment.

FIG. 7 shows a configuration of a movable scale according to a third modification of the first embodiment.

FIG. 8 shows a configuration of an encoder head used according to the movable scale shown in FIG.

FIG. 9 shows a configuration of a movable scale according to a fourth modification of the first embodiment.

FIG. 10 shows a configuration of an encoder head used according to the movable scale shown in FIG.

FIG. 11 shows a configuration of a photodetector for movement detection in a fifth modification of the first embodiment.

FIG. 12 shows a configuration of a movable scale according to a sixth modification of the first embodiment.

FIG. 13 is a perspective view illustrating a schematic configuration of an optical linear encoder according to a second embodiment of the present invention.

FIG. 14 is a perspective view illustrating a schematic configuration of an optical linear encoder according to a third embodiment of the present invention.

FIG. 15 is a perspective view illustrating a schematic configuration of an optical linear encoder according to a fourth embodiment of the present invention.

FIG. 16 is a plan view of the movable scale shown in FIG.

FIG. 17 shows a modification of the encoder head according to the fourth embodiment.

FIG. 18 shows another modified example of the encoder head according to the fourth embodiment.

FIG. 19 shows a configuration of a movable scale applicable to the first to fourth embodiments.

FIG. 20 shows a configuration of another movable scale applicable to the first to fourth embodiments.

FIG. 21 shows a configuration of another movable scale applicable to the first to fourth embodiments.

FIG. 22 shows a configuration of still another movable scale applicable to the first to fourth embodiments.

FIG. 23 shows a configuration of a photodetector for movement detection applicable to the first to fourth embodiments.

FIG. 24 shows another configuration of a photodetector for movement detection applicable to the first to fourth embodiments.

FIG. 25 shows a configuration of another movement detecting photodetector applicable to the first to fourth embodiments.

FIG. 26 is a perspective view showing a schematic configuration of an optical rotary encoder according to a fifth embodiment of the present invention.

FIG. 27 is a plan view of the rotary scale shown in FIG. 26;

FIG. 28 is a plan view of an encoder head applied to the optical rotary encoder of FIG.

FIG. 29 is a plan view of another encoder head applied to the optical rotary encoder of FIG. 26;

30 is a plan view of another encoder head applied to the optical rotary encoder of FIG.

FIG. 31 is a perspective view illustrating a schematic configuration of an optical rotary encoder according to a sixth embodiment of the present invention.

FIG. 32 shows a reflective optical encoder as a first conventional technique.

FIG. 33 shows a transmission type optical encoder as a second conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 Optical linear encoder 102 Encoder head 104 Movable scale 110 Substrate 112 First optical pattern 114 Second optical pattern 122 Coherent light source 124 First photodetector 126 Second photodetector

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jun Hane 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term in Olympus Optical Co., Ltd. (reference) 2F065 AA02 AA07 AA09 DD02 FF02 FF15 FF42 FF48 FF49 FF51 GG04 GG07 GG12 GG15 HH15 JJ02 JJ05 JJ18 LL08 LL10 LL36 LL42 2F103 BA32 CA01 CA02 CA04 CA08 DA01 DA12 DA13 EA02 EA12 EA15 EA19 EA20 EB02 EB12 EB16 EB27 EB32 EB37 EC01 EC14 2H049 AAAAAAAAAAAAAAAAAAAAAAA

Claims (55)

[Claims] A movable scale on which an optical pattern having a predetermined period is formed; a coherent light source for irradiating the optical pattern surface with a light beam of a predetermined shape substantially perpendicularly; and a light source reflected from the optical pattern. An optical encoder for receiving a light beam and detecting a diffraction pattern generated on the light receiving surface by the optical pattern. 2. The optical encoder according to claim 1, wherein the optical pattern is formed on the movable scale in a multiple number. 3. The optical encoder according to claim 2, wherein the plurality of optical patterns are all optical patterns having the same period. 4. The optical encoder according to claim 2, wherein the plurality of optical patterns include optical patterns having different periods. 5. The movable scale according to claim 1, wherein a holographic pattern having a function of reflecting and condensing the light beam is formed on the movable scale. Optical encoder. 6. The optical encoder according to claim 5, wherein the holographic pattern is used for detecting a reference position. 7. An optical system according to claim 1, further comprising means for suppressing the light beam reflected by the movable scale from returning to the light source. encoder. 8. The reflectance of the scale surface at a portion where the main axis of the light beam intersects the scale surface is lower than that of the optical pattern portion.
The optical encoder according to 1. 9. The optical encoder according to claim 7, further comprising means for rotating the plane of polarization by 90 degrees between the light source and the scale surface. 10. The means for rotating the plane of polarization is 1/4.
The optical encoder according to claim 9, wherein the optical encoder is a wave plate. 11. The optical encoder according to claim 1, wherein said light detecting means includes a plurality of light receiving areas formed on the same base slope. 12. The length of the main axis of the light beam from the coherent light source to the optical pattern is z1, the length of the main axis of the light beam from the optical pattern to the light receiving surface of the light detection means is z2, The pitch of a predetermined part of the pattern is p1,
When n is a natural number, the light receiving area of the light detecting means is
12. A light receiving area group having a light receiving area substantially at a position of np1 (z1 + z2) / z1 in a pitch direction of a predetermined portion of the diffraction pattern formed on the light receiving surface. Optical encoder as described. 13. The optical encoder according to claim 1, wherein the light source and the light detection means are provided on a same substrate in a hybrid or monolithic manner. . 14. The optical encoder according to claim 1, wherein the light source is mounted on a substrate on which the photodetector is formed. 15. The optical encoder according to claim 1, wherein the coherent light source is a surface emitting laser. 16. The coherent light source emits a light beam also from a surface opposite to a surface from which a light beam is emitted toward the optical pattern, and receives the latter light beam to reduce the intensity. 2. The apparatus according to claim 1, further comprising: an intensity detecting means for detecting; and means for controlling a light beam intensity of the coherent light source using a detection result of the intensity detecting means.
An optical encoder according to claim 15. 17. A rotatable scale in which an optical pattern having a predetermined period is formed in a circumferential direction of rotation, a coherent light source for irradiating a light beam of a predetermined shape substantially perpendicularly to the optical pattern surface, An optical encoder comprising: a light detecting unit that receives a light beam from the light source via the optical pattern and detects a diffraction pattern generated on a light receiving surface by the optical pattern. 18. The optical encoder according to claim 17, wherein the coherent light source is located on a rotation axis. 19. The optical encoder according to claim 17, wherein the optical encoder is of a reflection type. 20. The diffraction pattern on the light receiving surface,
18. The image forming apparatus according to claim 17, wherein the image is generated in a shape of a full circle.
20. The optical encoder according to claim 19. 21. The optical encoder according to claim 17, further comprising means for suppressing the light beam reflected by the scale from returning to the light source. . 22. The reflectance of the scale surface at a portion where the main axis of the light beam intersects the scale surface is lower than that of the optical pattern portion. An optical encoder according to one. 23. Between the light source and the scale surface,
22. The optical encoder according to claim 17, further comprising: means for rotating the polarization plane by 90 degrees. 24. The means for rotating the plane of polarization is 1/4.
The optical encoder according to claim 23, wherein the optical encoder is a wave plate. 25. A movable scale on which an optical pattern having a predetermined period is formed, a coherent light source for irradiating a light beam of a predetermined shape on the optical pattern surface, and receiving a light beam from the light source via the optical pattern. And light detecting means for detecting a diffraction pattern generated on a light receiving surface by the optical pattern, wherein the light detecting means is configured not to receive light of the main axis of the light beam. Optical encoder. 26. A coherent light source that emits a light beam having a predetermined shape, and is relatively displaced so as to cross the light beam emitted from the coherent light source, and generates a diffraction interference pattern by the light beam. A scale formed with an optical pattern having a predetermined period, and a photodetector for detecting a predetermined portion of a diffraction interference pattern generated by the optical pattern, from the coherent light source to an optical pattern formed on the scale. The length of the main axis of the traveling light beam is z1,
The length of the main axis of the light beam traveling from the optical pattern formed on the scale to the light receiving area of the photodetector is z
2. When the pitch of a predetermined portion of the optical pattern formed on the scale is p1, n is a natural number, the light receiving area of the photodetector is the predetermined area of the diffraction interference pattern formed on the light receiving area. Approximately np1 in the pitch direction of the part
An optical encoder having a light intensity detecting means constituted by a light receiving area group having a light receiving area at a position of (z1 + z2) / z1, wherein the light receiving area group of the photodetector is formed on the light receiving area. An optical encoder, wherein the optical encoder does not have effective light detection sensitivity or is shielded from light near the main axis of the light beam with respect to the diffraction interference pattern. 27. The optical encoder according to claim 26, wherein a main axis of a light beam emitted from the light source is incident substantially perpendicular to a pattern surface of the scale. 28. A low-reflection region, wherein a predetermined area on the scale on which the main axis of the light beam emitted from the light source is irradiated is configured to reduce the reflected light intensity of the light beam emitted from the light source. The optical encoder according to claim 27, wherein the optical encoder is a region. 29. The scale has a plurality of optical patterns, and a predetermined region of a light beam emitted from the coherent light source is irradiated on a plurality of optical patterns formed on the scale, and the plurality of optical patterns are formed on the scale. Light reflected by the optical pattern,
28. The optical encoder according to claim 26, further comprising a plurality of photodetectors each receiving a predetermined portion of transmitted light or diffracted light. 30. A predetermined region of the optical pattern of the scale having the predetermined period has at least one optical pattern different from the predetermined period, and a first predetermined region of the light beam emitted from the light source. A photodetector that is incident via the optical pattern of the scale, and another photodetector in which a predetermined area different from the first predetermined area of the light beam is incident via the optical pattern of the scale 28. The optical encoder according to claim 26 or claim 27, comprising: 31. The optical encoder according to claim 29, wherein the plurality of photodetectors are a plurality of light receiving areas formed on the same substrate. 32. The light source according to claim 26, wherein the light source is a coherent light source that is hybridly or monolithically integrated on the same substrate as the photodetector. Optical encoder. 33. The optical encoder according to claim 32, wherein the coherent light source is a surface emitting laser. 34. A light receiving area group of the photodetector has at least first and second two light receiving area groups in a moving direction of a scale, and a first one of diffraction interference patterns by an optical pattern on the scale. 27. A light receiving area group comprising: a first light receiving area group for detecting a phase region; and a second light receiving area group for detecting a second phase region different from the first phase region. 33. The optical encoder according to any one of 33. 35. A light-receiving area group of the photodetector has first to fourth four light-receiving area groups in the moving direction of the scale in order, and includes a diffraction interference pattern formed by an optical pattern on the scale. A first light receiving area group for detecting a first phase region, a second light receiving area group for detecting a second phase region different from the first phase region, and the first and second phase regions A third light receiving area group that detects a third phase area different from the first light receiving area group, and a fourth light receiving area group that detects a fourth phase area different from the first, second, and third phase areas. 35. The optical encoder according to claim 34, comprising: 36. The surface emitting laser can emit a light beam forward and backward, and a light receiving area for light output measurement is provided on a predetermined portion of the photodetector where the surface emitting laser is disposed, A light beam emitted forward from the light source is applied to the scale, and a light beam emitted backward from the light source is disposed so as to be able to enter a light receiving area for light output measurement on the photodetector. An optical encoder according to claim 33. 37. The output of the surface emitting laser can be controlled by the output intensity of a light beam which is incident on the light output measuring light receiving area of the photodetector and is emitted behind the surface emitting laser. The optical encoder according to claim 36, characterized in that: 38. At least one of the plurality of optical patterns of the scale is formed by converting a predetermined area of the light beam emitted from the light source to a cylindrical hologram lens having a light condensing property in a moving direction of the scale. 31. An optical encoder according to claim 29 or claim 30. 39. The optical encoder according to claim 29, wherein at least one of the plurality of optical patterns of the scale is a hologram lens. 40. At least one of the light receiving areas of the photodetector for detecting the light beam condensed by the hologram lens has a width of p1 in the moving direction of the scale.
The optical encoder according to claim 38 or 39, wherein the optical encoder is shorter than (z1 + z2) / z1. 41. A polarization plane of a light beam emitted from the coherent light source and a polarization plane of the light beam traveling from the coherent light source toward the light source via the pattern surface of the scale. An optical element having an angle of about 90 degrees near an exit window of the coherent light source is provided on a main axis of a light beam emitted from the coherent light source to the scale. Item 28. The optical encoder according to Item 27. 42. The optical encoder according to claim 41, wherein said optical element is a quarter-wave plate. 43. A rotary scale rotatable relative to the photodetector and formed so that at least optical characteristics such as reflection, transmission, and diffraction periodically change.
A light source for irradiating the rotary scale; and a light detector having a light receiving area for receiving a predetermined region of reflected light, transmitted light, or diffracted light from the rotary scale, and reflected light from the rotary scale. An optical encoder for detecting a light / dark pattern by transmitted light or diffracted light by a light receiving area of the photodetector, wherein the light source is disposed on a substantially extended line of a rotation axis of the rotary scale. Type encoder. 44. The optical encoder according to claim 43, wherein a main axis of the light beam emitted from the light source is substantially perpendicularly incident near a rotation center of the rotary scale. 45. A light source, wherein the light source is a coherent light source for emitting a light beam having a predetermined shape, and wherein the rotary scale generates a diffraction interference pattern by the light beam emitted from the coherent light source. On a rotary scale having a periodic optical pattern on a predetermined radius r1, the optical detector is an optical encoder that is a photodetector that receives a predetermined portion of the diffraction interference pattern, wherein the coherent light source and the The distance between the pattern of the rotary scale and the light receiving area of the photodetector is determined by z1, the distance between the pattern surface of the rotary scale and the light receiving area of the photodetector is determined by a radius r2 = r1 (z1 + z2) / z1. A light intensity detecting means formed by a light receiving area group left of the light receiving area at the predetermined angular period position formed in the vicinity of the circumference having the radius r2 given The optical encoder according to claim 44, wherein: 46. The method according to claim 44, further comprising a low-reflection area at a central portion of the rotary scale, the low-reflection area being configured to reduce a reflected light intensity of a light beam emitted from the light source. Optical encoder. 47. The coherent light source, wherein the light source is a coherent light source, which is capable of emitting a light beam having a predetermined shape, which is integrally formed on the same substrate as the photodetector in a hybrid or monolithic manner. Item 45. The optical encoder according to Item 44. 48. The optical encoder according to claim 47, wherein the coherent light source is a surface emitting laser. 49. The optical device according to claim 47, wherein the light receiving area groups of the photodetectors are arranged at predetermined intervals on a circumference substantially centered on the surface emitting laser light source. Type encoder. 50. A light receiving area group of the photodetector has at least first and second light receiving area groups in a rotation direction of a rotary scale, and a first one of diffraction interference patterns by an optical pattern on the scale. 44. A light receiving area group for detecting a first phase area, and a second light receiving area group for detecting a second phase area different from the first phase area. Item 48. The optical encoder according to any one of Items 47. 51. A light receiving area group of the photodetector has first to fourth four light receiving area groups in the rotation direction of the rotary scale in order, and diffraction interference formed by an optical pattern on the scale. A first light receiving area group for detecting a first phase region of the pattern, a second light receiving area group for detecting a second phase region different from the first phase region, and the first and second A third light receiving area group for detecting a third phase region different from the phase region, and the first, second,
6. A fourth light receiving area group for detecting a fourth phase region different from the third phase region.
The optical encoder according to 0. 52. The surface emitting laser can emit a light beam forward and backward, and a light output measuring light receiving area is provided on a predetermined portion on the photodetector where the light source is arranged, and Irradiating the rotary scale with the light beam emitted forward, characterized in that the light beam emitted backward from the light source is arranged so as to be able to enter the light receiving area for light output measurement on the photodetector, 49. The optical encoder according to claim 48. 53. The output of the surface emitting laser can be controlled by the output intensity of a light beam which is incident on the light output measuring light receiving area of the photodetector and is emitted behind the surface emitting laser. The optical encoder according to claim 52, characterized in that: 54. An angle formed between the plane of polarization of the light beam emitted from the coherent light source and the plane of polarization of the light beam traveling from the light source to the light source via the pattern surface of the scale. 45. The optical device according to claim 44, wherein an optical element having an angle of about 90 degrees near an exit window of the light source is provided on a main axis of a light beam emitted from the coherent light source to the scale. Optical encoder. 55. The optical encoder according to claim 54, wherein the optical element is a quarter wave plate.