JPH11166809A - Relative position detection device - Google Patents

Abstract

(57) [Abstract] [Problem] To arrange a distance between a scale and an index scale widely, to avoid damage due to contact and to prevent functional deterioration due to adhesion of dust, and in a direction perpendicular to the moving direction of the scale. The degree of freedom for the movement of the scale and the inclination of the scale is improved. A light source that emits coherent light is provided.
A collimating lens 102 for condensing light emitted from the light source 101 and optically correcting the light from the light source 101 into a substantially parallel light beam; a slit 103 having a periodic pattern structure with a predetermined light transmittance for dividing the light from the collimating lens 102; A scale 104 having a predetermined reflectance or transmittance and having the same periodic pattern as the slit 103 has a periodic pattern, and reflected light or transmitted light obtained by irradiating the scale 104 with light passing through the slit 103 is incident. And slit 10
A light receiving unit 105 for detecting the light intensity of reflected light or transmitted light generated due to a change in the relative position between the scale 3 and the scale 104
With.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relative position detection which can be used as an encoder (optical scale) for detecting a moving amount of a moving body in various measuring devices, various measuring devices, machine tools, copying machines, and the like. Related to the device.

[0002]

2. Description of the Related Art Conventionally, as a reference technical document relating to a relative position detecting device, for example, Japanese Patent Laid-Open No. 59-13211 has been disclosed. This configuration is shown in FIG. In the drawing, 1 is a light source, 2 is a collimating lens for optically correcting the light from the light source 1 into parallel rays and projected on a scale described later, 3 is a scale composed of an optical grating having a constant lattice constant, and 4 is a scale. 3 is an index scale including an optical element having the same lattice constant as 3. The index scale 4 is shifted by １ ／ wavelength from each other.
Has two grids. Reference numerals 5 and 5 'denote detectors for detecting light passing through each of the two optical gratings, and reference numeral 6 denotes an arrow indicating the moving direction of the scale 3.

In the above configuration, when the scale 3 is moved in the direction of the arrow 6, the passage and cutoff of light are repeated depending on the relative positional relationship with the index scale 4.
By detecting the change in the amount of light caused by the repetition of passing and blocking of the light by the detections 5 and 5 '. A sinusoidal electric signal is obtained, and the amount of movement is measured by counting this.

[0004]

However, in the prior art as described above, in order to increase the resolution accuracy, a scale having a small lattice constant may be used, but the contrast is not improved. In order to maintain the scale, it is necessary to dispose the scale and the index scale in a positional relationship with a very small interval, so that there is a problem that the function of the device is deteriorated due to damage due to contact or adhesion of dust. Also,
Since it is necessary to dispose the head section including the scale and other components very close to each other, there is also a problem that the degree of freedom for measurement of the vibrating object and movement of the measured object in the optical axis direction is small.

The present invention has been made in view of the above, and has a configuration in which the distance between the scale and the index scale is widely set apart, thereby deteriorating the function due to damage due to contact and adhesion of dust. And to improve the degree of freedom for movement in the direction perpendicular to the movement direction of the scale and inclination of the scale.

[0006]

According to a first aspect of the present invention, there is provided a relative position detecting device, comprising: a light source for emitting coherent light; and a light source for collecting light emitted from the light source. A collimating lens that illuminates and optically corrects the light into a substantially parallel light beam, a slit having a periodic pattern structure with a predetermined light transmittance that divides the light from the collimating lens,
A scale having a predetermined reflectance or transmittance and having the same periodic pattern as that of the slit, and reflected light or transmitted light obtained by irradiating the scale with light that has passed through the slit is incident. And light receiving means for detecting the light intensity of reflected light or transmitted light generated as the relative position between the slit and the scale changes.

That is, a periodic pattern of light transmittance is provided as a slit so as to have the same cycle as the change cycle of the reflectance or transmittance of the scale, and the reflected light obtained by irradiating the scale with the light passing through the slit. Alternatively, by transmitting transmitted light and detecting the light intensity of the reflected or transmitted light generated by the change in the relative position between the slit and the scale, the distance between the optical head that projects the light and the DUT can be increased. As a result, it is possible to avoid damage due to contact and functional deterioration due to the attachment of dust, and to improve the degree of freedom for movement in the direction perpendicular to the scale movement direction and scale inclination. Become.

According to a second aspect of the present invention, there is provided a relative position detecting device, comprising: a light source for emitting coherent light; and a collimating lens for condensing the light emitted from the light source and optically correcting the light to a substantially parallel light beam. A slit having a periodic pattern structure having a predetermined light transmittance for dividing light from the collimating lens, a scale having a predetermined reflectance, and having the same periodic pattern as the periodic pattern of the scale;
A light splitting means for splitting the light between the slit and the scale so that the directions of the projected light and the reflected light on the scale are symmetrical; and a light passing through the slit being passed through the light splitting means. A light receiving unit that irradiates the scale, reflects the reflected light through the light splitting unit, and detects a light intensity of a reflected light or a transmitted light generated according to a change in a relative position between the slit and the scale; It is provided with.

That is, in addition to the first aspect, since the parallel light beam is incident perpendicularly to the scale, even if the scale vibrates and moves in the optical axis direction, there is no detection error and accurate detection is possible. Relative values are obtained.

According to a third aspect of the present invention, there is provided a relative position detecting device according to the first or second aspect, further provided in front of the light receiving means for transmitting the transmitted light from the scale. Alternatively, a light condensing lens for condensing the reflected light on the light receiving means is provided.

In other words, in addition to the first or second aspect, the transmitted light or reflected light from the scale is guided to the light receiving means by the condenser lens, so that a photodetector (PD) having a smaller area can be used and the detection speed is improved. I do.

According to a fourth aspect of the present invention, in the relative position detecting device according to the second aspect, the light splitting means is a partial reflection mirror that reflects only the light collimated by the collimating lens, and The collimating lens has an arrangement or a lens characteristic for slightly condensing or diverging light emitted from the light source.

That is, in addition to the configuration of claim 2, an arrangement or lens that uses a partially reflecting mirror that reflects only the light collimated by the collimating lens and that the collimating lens slightly condenses or diverges the light emitted from the light source. By having the characteristics, the light use efficiency is improved, and stable measurement is possible.

According to a fifth aspect of the present invention, in the relative position detecting device according to the second aspect, the light splitting means is a partially transmitting mirror that transmits only the light collimated by the collimating lens, and The collimating lens has an arrangement or a lens characteristic for slightly condensing or diverging light emitted from the light source.

That is, in addition to claim 2, an arrangement or lens using a partially transmitting mirror that transmits only the light collimated by the collimating lens, and the collimating lens minutely condensing or diverging the light emitted from the light source. By having the characteristics, the light use efficiency is improved, and stable measurement is possible.

According to a sixth aspect of the present invention, in the second aspect, the light source is a laser light source that emits linearly polarized light, and the light splitting unit is configured to project light onto the scale. It comprises a polarizing beam splitter that polarizes and splits the light so that the directions of the light and the reflected light are symmetrical, and a quarter-wave plate that corrects the polarization of the light projected on the scale and the reflected light. .

That is, in addition to claim 2, a laser light source that emits linearly polarized light is used, and the light dividing means polarizes and splits the light so that the directions of the light projected and reflected on the scale are symmetrical. In addition, by adopting a configuration in which the projection light to the scale and its reflected light are polarization-corrected, the light use efficiency is improved and stable measurement is possible.

According to a seventh aspect of the present invention, in the relative position detecting device according to the third aspect, the collimating lens has an arrangement or a lens characteristic for slightly condensing or diverging light from the light source, Further, the light source, the collimator, and the condenser lens are integrally formed.

That is, by integrating the light source, the collimator, and the condenser lens, the size of the apparatus can be reduced, and the light source can be integrally formed on the same resin.
The complicated and difficult adjustment work such as the alignment between the lens and the light source is not required.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a relative position detecting device according to the present invention will be described in detail with reference to the accompanying drawings.

[Embodiment 1] FIG. 1 is an explanatory diagram showing a main configuration of a relative position detecting device (light transmission type) according to Embodiment 1. In the figure, reference numeral 101 denotes a light source, 102 denotes optical correction of light from the light source 101 to substantially parallel light, and
Reference numeral 103 denotes a collimating lens for projecting light, 103 denotes a slit for dividing the light emitted by the collimating lens 102, 104 denotes a scale on which a pattern in which the transmittance changes at a constant period is formed, and 105 denotes a scale 104.
And a light-receiving unit as light-receiving means for detecting the transmitted light that has passed through and illuminated and reflected on the scale 104.

Note that an LED, a semiconductor laser, or the like can be used as the light source 101, and a semiconductor laser that does not easily generate aberration when converted into a substantially parallel light beam by the collimating lens 102 is preferable.

Since the slit 103 generates a pattern beam having the same period as the period of the transmittance of the scale on the scale 104, a transmission pattern having the same period as the scale 104 may be used as long as it is perfectly parallel light. Also,
Even if the period is not completely the same, it can be used if the pattern of the light beam can be adjusted to the same period as the scale 104 by the collimating lens 102.

In the relative position detecting device configured as described above, the light from the light source 101 is
The light beam is converted into a parallel light beam by 2 and projected on a scale 104 through a slit 103. At this time, a pattern beam having the same pitch as the scale 104 is formed on the scale 104 as shown in FIG. Therefore, the pattern beam repeats blocking / transmission by the movement of the scale 104, and a light amount change due to the blocking / transmission is detected by the light receiving unit 105.

Usually, the slit 103 may have the pattern shown in FIG. 3, but in order to detect the moving direction of the scale 104, as shown in the slit of FIG. And by detecting signals with different photodetectors, it is possible to obtain A and B phase signals generally used in encoders.

The relative position detecting device uses a light transmission type scale 103 as shown in FIG. 1, but has a light reflection type scale 103 as shown in FIG. Is also good. In this case, as shown in FIG. 5, the light incident on the scale 104 is tilted, and the light
05 can be realized. At this time,
The direction in which the light beam is tilted is essentially the same whether it is in the illustrated direction or in a different direction.

Therefore, according to the first embodiment,
Since the slit 103 and the scale 104 can be separated from each other, it is possible to realize an apparatus that is resistant to damage due to contact between the scale and the index scale and contamination such as dust in a poor environment as in the related art.

[Embodiment 2] By the way, in a relative position detecting device using a reflection type scale, an error may occur with respect to a change in a detection distance. That is, in a relative position detecting device using a reflective scale as shown in FIG.
Light projection and reflection on the scale 104 need to be inclined with respect to the scale 104. In such a configuration, when the detection distance (the distance between the light emitting / receiving unit and the scale) changes during measurement, the detection position shifts as shown by a broken line, and an error of d occurs. In the second embodiment, an example of solving this problem will be described.

FIG. 6 is an explanatory diagram showing the main configuration of the relative position detecting device (light reflection type) according to the second embodiment. This relative position detection device is different from the light reflection type configuration of the first embodiment (see FIG. 5) in that a beam splitter 106 as a light splitting means for vertically projecting and reflecting light on the scale 104 is provided. , Slit 103 and light receiving unit 105
And is provided between them. Therefore, the other components and their functions are the same as those in the first embodiment, and therefore are denoted by the same reference numerals as those in FIG. 1 and their description is omitted.

As shown in FIG. 6, the beam splitter 106 is disposed at an intermediate portion where the light emitting portion including the light source 101, the collimating lens 102 and the slit 103 and the light receiving portion 105 are arranged at a right angle.

In the relative position detecting device configured as described above, the light projecting unit (light source 101, collimating lens 10
2, about 50% of the light amount of the parallel light beam projected from the slit 103) is bent at a right angle by the beam splitter 106, and is irradiated perpendicularly to the scale 104. At this time, since the scale 104 is of a reflection type, the irradiated light beam is reflected regularly and returns to the beam splitter 106.
The beam splitter 106 partially reflects the light, but approximately 50% goes straight and enters the light receiving unit 105, where a signal is detected. After that, a relative value is detected as in the first embodiment.

Therefore, similarly to the transmission type relative position detection device described in the first embodiment, since the light beam is incident on the scale 104 perpendicularly, the scale vibrates and moves in the optical axis direction. Also, the occurrence of an error can be prevented, and an accurate relative value can be detected. Further, by adopting the light reflection type, it is possible to accommodate a device having the same performance as the light transmission type (through type) in a small space.

[Embodiment 3] In this embodiment 3,
An example in which the signal detection speed is further improved and the degree of freedom of the inclination of the scale 104 is increased compared to the first and second embodiments will be described.

FIG. 8 is an explanatory diagram showing a main configuration of a relative position detecting device (light reflection type) according to the third embodiment. This relative position detection device is different from the light reflection type (see FIG. 6) of the second embodiment in that a light-receiving condenser lens 107 is provided between the beam splitter 106 and the light-receiving unit 105.
Therefore, the other components and their functions are the same as those in the second embodiment, and therefore, are denoted by the same reference numerals as in FIG. 6, and the description thereof will be omitted.

In the first and second embodiments, the scale 10
In order to receive the specularly reflected light from No. 4, a photodetector having a size at least equal to the beam diameter is required. further,
In order to allow the inclination of the scale 104 and the light emitting / receiving unit, the beam needs to have a circular shape. The diameter is D, the distance between the photodetector and the scale 104 is L,
Assuming that the allowable inclination error is Δθ, Pd = 2L sin Δθ + D (1) The diameter Pd of the photodetector is required.

For example, D = 0.5 mm, L = 50 m
If m, Δθ = ± 2 °, a diameter of about 7.5 mm is required. Usually, in the case of a photodetector (PD) used as a photodetector, the capacitance is proportional to the area of the photodetector, and an increase in the required area impedes an improvement in signal detection speed. Therefore, it is desirable to use a photodetector (PD) having an area as small as possible.

For this reason, the aperture of the condenser lens 107 for irradiating the PD with the received light has a diameter larger than the equation (1).
FIG. 9 shows a beam image on the scale 104 according to the third embodiment.

Therefore, in the third embodiment, the light beam to be received is condensed by the condensing lens 107 and the light is irradiated on the light receiving section 105, so that the light can be received by the photodetector (PD) having a smaller area. Speed is improved.

Also, as in the case of the relative position detecting device described in the second embodiment, since the light beam is incident on the scale 104 perpendicularly, even if the scale vibrates or moves in the optical axis direction, an error occurs. Can be prevented, and an accurate relative value can be detected. Further, by adopting the light reflection type, it is possible to accommodate a device having the same performance as the light transmission type (through type) in a small space.

[Embodiment 4] FIG. 10 shows Embodiment 3 of the present invention.
It is an explanatory view showing the main composition of the relative position detecting device (light reflection type) concerning. This relative position detecting device is a partial reflection mirror 10 as a light splitting means for reflecting only the beam portion of the light emitted from the collimating lens 102 instead of the beam splitter 106 of the relative position detecting device shown in FIG.
8 are arranged so as to condense or diverge the light emitted from the collimator lens 102 or have a lens constant. Further, the collimator lens 102 is arranged to slightly condense / diverge the light from the light source 101 or has a lens constant. The partial reflection mirror 10
Numeral 8 is set to be substantially the same as the beam diameter of the incident / reflected light beam. Therefore, the other components and their functions are the same as those in the second embodiment, and therefore, are denoted by the same reference numerals as in FIG. 6, and the description thereof will be omitted.

Here, a case will be described by way of example in which the light beam from the lens is set to slightly diverge. The same applies to the case where a slightly converging light beam is used. The light emitted from the light source 101 is transmitted to a collimator lens 102.
, And further passes through the slit 103 to be divided into substantially parallel light. This light beam is partially reflected mirror 1
08 and scale 10 at a slight angle
4 is incident.

The light beam applied to the scale 104 is specularly reflected symmetrically with the angle of incidence according to the law of reflection, and enters the light receiving unit 105. At this time, if the light beams projected from the light projecting unit are parallel, the light is almost vignetted by the partial reflection mirror 108, but most of the light beams can be guided to the light receiving unit 105 by setting it to slightly divergent. it can.

In the second embodiment, the light emission efficiency is 5
A loss of 0% and a light receiving efficiency of 50% occurs, resulting in a light use efficiency of 25% or less. However, in the fourth embodiment, the light emitting efficiency 100% and the light receiving efficiency η are determined by the following equation (2) from the diverging and converging angles.

That is, the light receiving efficiency is represented by η = 2πL sin θ · (2πL sin θ + D) (2) Here, L is the optical path length from the time when the light is reflected from the collimator lens 102 to the scale 104 and vignetted by the partial reflection mirror 108, θ is the divergence angle, and D
Is the effective diameter of the partial reflection mirror 108.

Therefore, according to the fourth embodiment,
By providing a partial reflection mirror 108 that reflects only the beam portion of the light emitted from the collimating lens 102, and by further arranging the collimating lens 102 to slightly condense / diverge the light from the light source 101, or by providing a lens constant. The light use efficiency is improved, and more stable measurement is possible.

[Fifth Embodiment] FIG. 11 shows a fifth embodiment.
It is an explanatory view showing the main composition of the relative position detecting device (light reflection type) concerning. This relative position detecting device is different from the partial reflecting mirror 108 of the relative position detecting device shown in FIG. 10 in that a partial transmission mirror 10 as a light splitting means for transmitting only a beam portion of the light emitted from the collimating lens 102 is used.
9 is arranged so that the light emitted from the collimator lens 102 is condensed or diverged, or has a lens constant. Further, the collimator lens 102 is arranged to slightly condense / diverge the light from the light source 101 or has a lens constant. The partially transmitting mirror 10
Numeral 9 is set to be substantially the same as the beam diameter of the incident and transmitted light beam. Therefore, the other components and their functions are the same as those of the fourth embodiment, and therefore, are denoted by the same reference numerals as in FIG. 10 and the description thereof is omitted.

Here, as in the case of the fourth embodiment, a case will be described as an example where the light rays by the lens are set to slightly diverge. The same applies to the case where a slightly converging light beam is used. The light emitted from the light source 101 is
The light is diverged by the collimating lens 102, further passes through the slit 103, and becomes divided into substantially parallel light. This light beam is transmitted by the partially transmitting mirror 109 and enters the scale 104 at a slight angle.

The light beam applied to the scale 104 is specularly reflected symmetrically with the incident angle according to the law of reflection, and is incident on the light receiving unit 105. At this time, if the light beams projected from the light projecting unit are parallel, the light is almost vignetted by the partially transmitting mirror 109, but most of the light beams can be guided to the light receiving unit 105 by setting it to be slightly divergent. it can.

In the fifth embodiment, similarly to the fourth embodiment, the light emitting efficiency 100% and the light receiving efficiency η are determined from the divergence / condensing angle by the above-mentioned equation (2).

Therefore, according to the fifth embodiment,
By providing a partially transmitting mirror 109 for transmitting only the beam portion of the light emitted from the collimating lens 102, and further arranging the collimating lens 102 to slightly condense / diverge the light from the light source 101, or by providing a lens constant. The light use efficiency is improved, and more stable measurement is possible.

Further, since the partially transmitting mirror 109 as in the fifth embodiment is laid out in the vertical direction with respect to the scale 104 as shown in FIG.
A compact device configuration can be realized in the moving direction of. Also,
The partially transmitting mirror 109 is easy to hold,
It is also advantageous on a surface where the vignetting of the light beam by the holding jig does not occur like the partial reflection mirror 108.

[Embodiment 6] FIG. 12 shows Embodiment 6 of the present invention.
It is an explanatory view showing the main composition of the relative position detecting device (light reflection type) concerning. In this relative position detecting device, a polarizing beam splitter 111 is disposed as a light splitting unit at the position of the boom splitter 106 of the relative position detecting device shown in FIG.
In this case, a system used for a so-called ordinary CD-ROM optical pickup in which a quarter-wave plate 110 is provided between the optical disk and the optical disk is adopted. Therefore, the other components and their functions are the same as those in the second embodiment, and therefore, are denoted by the same reference numerals as in FIG. 6, and the description thereof will be omitted.

In the relative position detecting device configured as shown in FIG. 12, the light is optically corrected by the collimator lens 102 emitted from the light source 101 into parallel light and passes through the slit 103. Further, the light that has passed through the slit 103 is reflected by the polarization beam splitter 111, and is reflected by the ４ wavelength plate 11.
The light passes through 0 and irradiates the scale 104. Scale 10
The light reflected by 4 passes through the 波長 wavelength plate 110, passes through the polarization beam splitter 111, and enters the light receiving unit 105. Thereafter, the same measurement operation as described above is performed.

According to the sixth embodiment, in addition to the effects of the above-described embodiment, light can be used with an efficiency of about 90% for both light emission and light reception, and stable measurement can be realized.

[Seventh Embodiment] FIG. 13 shows a seventh embodiment.
It is an explanatory view showing the main composition of the relative position detecting device (light reflection type) concerning. This relative position detecting device integrally includes the collimating lens and the light receiving lens in the above-described embodiment, and further includes a light source integrated lens 112 having a light source disposed on the lens optical axis between the scale 104 and the light receiving unit 105. Is provided. Therefore, the other components and their functions are the same as those in the above-described embodiment, and thus are denoted by the same reference numerals and description thereof will be omitted.

In FIG. 13, the light source integrated lens 112
The light from the light source 101 disposed in the
Scale 1 through 12 collimating lenses and slits
04. Further, the light emitted from the scale 104 is condensed by the light source integrated lens 112 as reflected light, and is incident on the light receiving unit 105. Thereafter, the same measurement operation as described above is performed.

Therefore, according to the seventh embodiment,
In particular, since the light source 101, the collimating lens 102, the slit 103, the light receiving lens, and the light receiving unit 105 are configured on the same optical path, the device becomes very small. Also, the light source 101
Also, by integrally molding the same resin, the adjustment work such as the optical axis alignment of the lens and the light source 101 becomes unnecessary.
Productivity also increases.

[0058]

As described above, according to the relative position detecting device according to the present invention (claim 1), the light transmittance of the scale is the same as the change period of the reflectance or the transmittance of the scale. A periodic pattern is provided as a slit, and reflected light or transmitted light obtained by irradiating the scale with the light passing through the slit is incident thereon, and the reflected light or transmitted light generated due to a change in the relative position between the slit and the scale. By detecting the intensity, the distance between the optical head that projects light and the object to be measured can be kept wide, so that damage due to contact and functional deterioration due to the adhesion of dust can be avoided, and the scale can be moved. The degree of freedom with respect to movement in the direction perpendicular to the direction and inclination of the scale can be improved.

Further, according to the relative position detecting device according to the present invention (claim 2), in addition to the constitution described in claim 1, since the parallel light beam is incident perpendicularly to the scale, vibration of the scale and light Even if movement in the axial direction occurs, there is no detection error and an accurate relative value can be obtained.

Further, according to the relative position detecting device according to the present invention (claim 3), in addition to claim 1 or 2, the light condensing lens guides the transmitted light or reflected light from the scale to the light receiving means. Small area photodetector (P
D) can be used, and the detection speed can be improved.

According to the relative position detecting device of the present invention (claim 4), in addition to claim 2, a partial reflection mirror that reflects only the light collimated by the collimating lens is used, and the collimating lens is a light source. Since it has an arrangement or a lens characteristic that slightly condenses or diverges the light emitted from the device, the light use efficiency is improved and stable measurement is possible.

Further, according to the relative position detecting device according to the present invention (claim 5), in addition to claim 2, a partially transmitting mirror that transmits only the light collimated by the collimating lens is used, and the collimating lens is a light source. Since it has an arrangement or a lens characteristic that slightly condenses or diverges the light emitted from the device, the light use efficiency is improved, and stable measurement is possible.

Further, according to the relative position detecting device of the present invention (claim 6), in addition to claim 2, a laser light source for emitting linearly polarized light is used, and the light splitting means uses the laser light for projecting light to the scale and Since the light is polarized and split so that the direction of the reflected light is symmetric, and the light projected on the scale and the reflected light are corrected for polarization, the light use efficiency is improved and stable measurement is possible. Become.

Further, according to the relative position detecting device of the present invention (claim 7), since the light source, the collimator and the condenser lens are integrated, the size of the device can be reduced and the light source can be the same. Since it is integrally molded on resin, complicated and difficult adjustment work such as alignment of a lens and a light source is not required.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a main configuration of a relative position detection device (light transmission type) according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram showing a beam image on a scale according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a slit according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of an AB-phase slit pattern of the slit according to the first embodiment of the present invention;

FIG. 5 is an explanatory diagram illustrating a main configuration of a relative position detection device (light reflection type) according to Embodiment 1 of the present invention.

FIG. 6 is an explanatory diagram showing a main configuration of a relative position detection device (light reflection type) according to Embodiment 2 of the present invention.

FIG. 7 is an explanatory diagram showing a detection distance measurement error in the light reflection type relative position detection device.

FIG. 8 is an explanatory diagram showing a main configuration of a relative position detection device (light reflection type) according to Embodiment 3 of the present invention.

FIG. 9 is an explanatory diagram showing a beam image of a scale according to Embodiment 3 of the present invention.

FIG. 10 is an explanatory diagram showing a main configuration of a relative position detection device (light reflection type) according to Embodiment 4 of the present invention.

FIG. 11 is an explanatory diagram showing a main configuration of a relative position detection device (light reflection type) according to Embodiment 5 of the present invention.

FIG. 12 is an explanatory diagram showing a main configuration of a relative position detection device (light reflection type) according to Embodiment 6 of the present invention.

FIG. 13 is an explanatory diagram showing a main configuration of a relative position detection device (light reflection type) according to Embodiment 6 of the present invention.

FIG. 14 shows a conventional relative position detection device (light transmission type).
FIG. 3 is an explanatory diagram showing a main configuration of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Light source 102 Collimating lens 103 Slit 104 Scale 105 Light receiving part 106 Beam splitter 107 Light receiving lens 108 Partial reflection mirror 109 Partial transmission mirror 110 Quarter wave plate 111 Polarizing beam splitter 112 Light source integrated lens

Claims (7)

[Claims] 1. A light source that emits coherent light, a collimating lens that collects light emitted from the light source and optically corrects the light into a substantially parallel light beam, and a predetermined light transmission that splits light from the collimating lens. A slit having a periodic pattern structure of reflectance and a predetermined reflectance or transmittance,
A scale having the same periodic pattern as the periodic pattern of the slit, and reflected light or transmitted light obtained by irradiating the scale with light passing through the slit are incident, and the relative position between the slit and the scale is determined. A relative position detecting device comprising: a light receiving unit that detects the light intensity of reflected light or transmitted light generated by the change. 2. A light source that emits coherent light, a collimator lens that collects light emitted from the light source and optically corrects the light into a substantially parallel light beam, and a predetermined light transmission that splits light from the collimator lens. A slit having a periodic pattern structure of a ratio, a scale having a predetermined reflectance, and having the same periodic pattern as the periodic pattern of the scale, and light projected on the scale between the slit and the scale. And a light splitting means for splitting the light so that the direction of the reflected light is symmetric, and the light passing through the slit is irradiated on the scale via the light splitting means, and the reflected light is sent through the light splitting means. Light receiving means for detecting the light intensity of reflected light or transmitted light generated as the relative position between the slit and the scale changes. Relative position detector. 3. The light-receiving device according to claim 1, further comprising a condensing lens disposed in front of said light-receiving means for condensing transmitted light or reflected light from said scale on said light-receiving means. The relative position detecting device as described in the above. 4. The light splitting means is a partial reflection mirror that reflects only the light collimated by the collimating lens, and the collimating lens minutely condenses the light emitted from the light source. The relative position detecting device according to claim 2, wherein the relative position detecting device has a diverging arrangement or a lens characteristic. 5. The light splitting means is a partially transmitting mirror that transmits only the light collimated by the collimating lens, and the collimating lens minutely condenses the light emitted from the light source. The relative position detecting device according to claim 2, wherein the relative position detecting device has a diverging arrangement or a lens characteristic. 6. The light source is a laser light source that emits linearly polarized light, and the light splitting means polarizes and splits the light so that the directions of the light projected and reflected on the scale are symmetric. 3. The relative position detecting device according to claim 2, comprising a beam splitter and a quarter-wave plate for correcting the polarization of the light projected on the scale and the reflected light. 7. The collimating lens has an arrangement or a lens characteristic for minutely condensing or diverging light from the light source, and the light source, the collimator, and the condensing lens are integrally formed. The relative position detecting device according to claim 3, wherein