JPH10213455A - Optical linear encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical encoder, which is compact and has the high measuring accuracy. SOLUTION: An optical linear encoder has a scale 20 and a detecting head 30. The scale 20 comprises, e.g. a glass plate and has an optically detectable pattern. The detecting head 30 has the pattern detecting sensor for detecting movement of the pattern of the scale 20. The pattern detecting sensor has a light source part 32 for projecting the light toward the scale 20 and a light detector 34 for detecting the reflected light from the scale 20. The light source part 32 and the light detecting part 34 are bonded to a heat radiating and wiring substrate 36. The heat radiating substrate 36 is bonded to the slant part of a supporting stage 38. A holding member 40 is bonded to the supporting stage 38. The scale 20 is supported by a guiding groove 42 provided in the holding member 40 so that the scale can be moved in the longitudinal direction. At the upper surface of the guiding groove 42, a plate spring, which pushes the scale 20 to the lower surface of the guiding groove 42 in tight contact, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical encoder,
In particular, it relates to an optical linear encoder.

[0002]

2. Description of the Related Art An optical encoder has a detection head including a light source and a photodetector, and a scale plate having an optically detectable pattern. To be measured. The light source emits light toward the scale plate, and the photodetector receives light transmitted through the scale plate or reflected by the scale plate, and outputs a signal corresponding to the amount of incident light. The optically detectable pattern includes, for example, a large number of slits formed at a constant pitch on a slit plate, or a large number of strip-shaped reflectors provided at a constant pitch on a slit plate. The light transmitted through the scale plate and the light reflected by the scale plate are modulated according to the detection pattern, that is, the movement of the slit or the strip-shaped reflector. Therefore, the amount of movement of the scale plate with respect to the detection head can be obtained by examining the output signal of the photodetector, for example, by counting the peak of the signal.

Japanese Patent Laying-Open No. 7-49427 discloses an optical linear encoder. The scale is made of a band-shaped thin metal plate and has flexibility, and has a number of slits arranged at a constant pitch in the longitudinal direction. The scale is held at both ends by a scale holder and is tensioned in the longitudinal direction. The read head is provided so as to be movable in the longitudinal direction of the scale, and the amount of movement is measured by examining the intensity of light passing through the slit. The reading unit has two scale guide pins extending parallel to the plane of the scale and orthogonal to the longitudinal direction, and the scale guide pins are in contact with the scale and undesired movement in a direction perpendicular to the plane of the scale. Is regulated. Thereby, the vibration of the scale is suppressed, and the measurement accuracy is improved.

Japanese Patent Application Laid-Open No. 8-14810 discloses a magnetic linear encoder. The scale is made of an elastic thin plate of PET (polyethylene terephthalate) and has flexibility, and its surface is provided with magnetic pole patterns at a constant pitch. The scale passes through an insertion hole provided in the detection head and is movable with respect to the detection head. The movement amount of the scale is measured by reading a magnetic pole pattern using an MR head provided on the detection head. The insertion hole is designed so that its cross section is slightly larger than the cross section of the scale, thereby suppressing vibration of the scale and improving measurement accuracy.

[0005]

A flexible scale plate is generally made of a thin plate of resin or metal and has low dimensional stability. Therefore, a flexible scale plate is required to be used for a precise linear encoder for measuring a movement amount of 1 micron or less. Unsuitable for use.

[0006] On the other hand, a scale plate having high rigidity is made of a thick plate of glass or metal and has excellent dimensional stability, but requires a complicated mechanism for holding the scale plate, resulting in an increase in size of the apparatus. SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical encoder that is small in size thanks to a simple configuration while achieving high accuracy using a rigid scale plate.

[0007]

SUMMARY OF THE INVENTION An optical linear encoder according to the first aspect of the present invention comprises a detection head having a light source section and a light detection section, and a detection head having an optically detectable pattern. An optical linear encoder that has a plate-shaped scale that is movable in the optical linear encoder and that measures the moving distance of the scale with respect to the detection head by reading the pattern of the scale with the detection head. And a pressing member that presses the scale in a direction independent of the moving direction of the scale and makes the scale adhere to the supporting portion.

In this optical linear encoder, the scale is pressed by the pressing member in a direction independent of the moving direction (preferably, a direction perpendicular to the moving direction) and is in close contact with the supporting portion. Is always kept constant. Therefore, it is not necessary to readjust the position between the light source unit and the scale during use. This provides an optical encoder with a small number of optical elements, a simple configuration, and high measurement accuracy.

An optical linear encoder according to a second principal aspect of the present invention comprises: a detection head having a light source unit and a light detection unit;
A plate-like scale having an optically detectable pattern and movable with respect to the detection head, and measuring the distance of movement of the scale with respect to the detection head by reading the pattern of the scale with the detection head In the optical linear encoder, it is preferable that the optical linear encoder further includes a protrusion that abuts on the scale to secure a fixed distance between the detection head and the scale, and an elastic member that urges the detection head toward the scale. Features.

In this optical linear encoder, the detection head is urged toward the scale by the elastic member, the projection comes into contact with the scale to secure a constant distance between the scale and the detection head, and the scale is moved to the projection. Slides against Therefore, the distance between the light source unit and the scale is always kept constant. Thereby, a small-sized optical encoder with high measurement accuracy is realized.

An optical linear encoder according to a third principal aspect of the present invention includes a detection head having a light source unit and a light detection unit;
A plate-like scale having an optically detectable pattern and movable with respect to the detection head, and measuring the distance of movement of the scale with respect to the detection head by reading the pattern of the scale with the detection head In an optical linear encoder, interval variation detecting means for detecting variation in the interval between the light source unit and the scale, and interval control for moving the detection head based on the detected variation in the interval to keep the interval between the light source unit and the scale constant. Means.

In this optical linear encoder, the interval variation detecting means detects a variation in the interval between the light source unit and the scale, and
The interval control means moves the detection head so as to compensate for the variation in the detected interval, that is, to maintain the interval between the light source unit and the scale constant. With this control, the distance between the light source unit and the scale is always kept constant.
As a result, a compact optical encoder with high measurement accuracy is realized.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] An optical linear encoder according to a first embodiment will be described with reference to FIGS.

As shown in FIGS. 1 and 2, the optical linear encoder has a scale 20 and a detection head 30. The scale 20 is made of a rigid and elongated plate material, for example, a glass plate, and has an optically detectable pattern, for example, a light and dark pattern having a large number of thin strip-shaped reflectors arranged at a constant pitch in the longitudinal direction.

The detection head 30 has a pattern detection sensor for detecting the movement of the pattern on the scale 20.
The pattern detection sensor has a light source unit 32 that emits light toward the scale 20 and a light detection unit 34 that detects light reflected from the scale 20. As shown in FIG. 3, the light source unit 32 has two light emitting elements, for example, vertical cavity surface emitting lasers 32a and 32b, and the light detecting unit 34 has two light receiving elements, for example, photodiodes 34a and 34b.
The photodiode 34a receives light emitted from the vertical cavity surface emitting laser 32a and reflected by the scale 20, and outputs a signal corresponding to the amount of light. The photodiode 34b has a vertical cavity surface emitting laser. It receives light emitted from the light emitting laser 32b and reflected by the scale 20, and outputs a signal corresponding to the light amount.

The light source section 32 and the light detection section 34 are manufactured in series by a monolithic method, and are bonded to a heat dissipation / wiring board 36 as shown in FIGS. The heat dissipation and wiring board 36 is adhered to the slope of the support base 38.
For the bonding, for example, a photocurable adhesive is used. Support stand 3
A holding member 40 is bonded to 8. The support base 38 and the holding member 40 are manufactured using a photo-curable resin by, for example, an optical molding method.

The holding member 40 has a guide groove 42 for guiding the scale 20.
2 and is movably supported by the guide groove 42 in the longitudinal direction. As shown in FIG. 4, two pressing members, for example, a leaf spring 4 are provided on an upper surface 42 b of the guide groove 42.
4 is fixed, and the leaf spring 44 presses the scale 20 against the lower surface 42a of the guide groove 42 to make the scale 20 adhere to the surface 42a. This allows the scale 20 to move or slide in the longitudinal direction while maintaining contact with the surface 42a. FIG.
As shown in (2), another pressing member, for example, a leaf spring 46, may be provided on the lateral surface 42c of the guide groove 42 in order to suppress undesired lateral movement of the scale 20.

As shown in FIG. 1 to FIG.
The surface of the light detection unit 34 and the surface of the scale 20 are
They are arranged in a non-parallel manner so that the light from 2 is reflected by the scale 20 to the light detecting section 34, and the angle between them is 5 to 40 degrees, preferably 10 to 25 degrees.
The dimensions of the light emitting surfaces of the vertical cavity surface emitting lasers 32a and 32b are preferably 100 μm × 100 μm or less.
The width of the scale 20 is 200 μm to 10 mm, preferably 1 mm to 5 mm, and the thickness is 50 μm to 5 mm.
And preferably 200 μm to 1 mm. The distance between the light source unit 32 and the scale 20 is set such that the reflected light from the scale 20 enters the photodetection unit 34 well.
0 depending on the pitch of the pattern provided at 0, the inclination angle between the surface of the light source unit 32 and the surface of the scale 20, and the like.
0.1 mm to 2 mm, preferably 0.2 mm to
0.7 mm.

As shown in FIG. 3, the light source section 32 has two light emitting elements 32a and 32b, and the interval is a positive number of the pitch of the pattern of the scale 20, plus a quarter of the pitch. Length is set. For this setting, a pseudo sine wave signal whose phase is shifted by 90 degrees is output from the two light receiving elements 34a and 34b, and based on these two signals, the moving direction of the scale 20 can be detected in addition to the moving amount of the scale 20.

The optical linear encoder described above is mounted on a linear stage 200, which is an object to be measured, as schematically shown in FIG. 6, for example. The linear stage 200 has a fixed part 202 and a moving part 204 that can move with respect to the fixed part 202.
Guide 2 for ensuring the straightness of movement of the moving unit 204 and reducing friction between the moving unit 204 and the moving unit 204.
06 is provided. The scale 20 of the optical linear encoder is fixed to the moving part 204 of the linear stage 200, and the detection head 30 of the optical linear encoder is fixed to the fixing part 202 of the linear stage 200.

In the optical linear encoder of the present embodiment, as described above, the scale 20 is made of a rigid plate material such as glass, and thus has high dimensional stability. Further, since the scale 20 is pressed by the leaf spring 44 against the lower surface 42a of the guide groove 42 provided in the holding member 40, the distance between the light source 32 and the scale 20 is always kept constant.
Therefore, the amount of movement of the scale 20 with respect to the detection head 30 can be measured with high accuracy.

The mechanism for keeping the distance between the light source 32 and the scale 20 constant is a very simple one comprising a guide groove 42 provided in the holding member 40 and a leaf spring 44 provided therein. It is. Therefore, the optical linear encoder of the present embodiment can be manufactured very small.

[Second Embodiment] An optical linear encoder according to a second embodiment will be described with reference to FIGS. In the drawings, members already mentioned in the description of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted in the following description.

As shown in FIG. 8, both ends of the scale 20 are fixed to a fixed portion 56, and the fixed portion 56 is fixed to, for example, the moving portion 204 of the linear stage 200 shown in FIG. The detection head 30 is attached to a fixing jig 54 via an absorbing member 52 engaged with the detection head 30. The fixing jig 54 is fixed to, for example, a fixing portion 202 of a linear stage 200 shown in FIG. You.

As can be seen from FIG. 7 and FIG.
2 has a box shape, and a part of the detection head 30 is
There is a gap in the X direction and the Y direction, and there is no gap in the Z direction. Due to this engagement, the detection head 30 cannot move in the Z direction with respect to the absorbing member 52, but can move in the X direction and the Y direction.
Therefore, the displacement of the moving part 204 of the linear stage 200 in the X direction and the Y direction with respect to the fixed part 202 during the movement of the scale 20 with respect to the detection head 30 is caused by the X direction and the Y As a result, the contact between the guide groove 42 of the detection head 30 and the scale 20 is maintained.

As described above, in the optical linear encoder according to the present embodiment, even when the moving section 204 of the linear stage 200 is displaced from the fixed section 202 in the X direction or the Y direction,
Since the contact between the scale 20 and the guide groove 42 is maintained, the distance between the light source 32 and the scale 20 is always kept constant. Therefore, the amount of movement of the scale 20 with respect to the detection head 30 can be measured with high accuracy.

The mechanism for maintaining the contact between the scale 20 and the guide groove 42 includes a part of the detection head 30 and the scale 20.
And a box-shaped absorbing member 52 that can be accommodated so as to be movable in a direction perpendicular to the moving direction. Therefore, the optical linear encoder of the present embodiment can be manufactured very small.

Various modifications and changes can be made to this embodiment. For example, the engagement between the detection head 30 and the absorbing member 52 is performed when the detecting head 30
It may be one that can move only in the direction. Even with such engagement, it is possible to achieve that the distance between the light source 32 and the scale 20 is always kept constant.

Third Embodiment An optical linear encoder according to a third embodiment will be described with reference to FIGS. In the drawings, members already mentioned in the description of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted in the following description.

As shown in FIG. 10, the optical linear encoder has a scale 20 and a detection head 30. The scale 20 is made of a rigid and elongated plate material, for example, a glass plate, and has an optically detectable pattern, for example, a light and dark pattern having a large number of thin strip-shaped reflectors arranged at a constant pitch in the longitudinal direction.

The detection head 30 has a pattern detection sensor for detecting the movement of the pattern on the scale 20.
The pattern detection sensor has a light source unit 32 that emits light toward the scale 20 and a light detection unit 34 that detects light reflected from the scale 20. The light source unit 32 and the light detection unit 34 are manufactured in series by, for example, a monolithic method. The light source unit 32 and the light detection unit 34 are adhered to a heat dissipation and wiring board 36, and the heat dissipation and wiring board 36 is adhered to an inclined surface of a support base 38. For the bonding, for example, a photocurable adhesive is used. The holding member 40 is adhered to the support base 38. The support base 38 and the holding member 40 are manufactured using a photo-curable resin by, for example, an optical molding method. The holding member 40 is a scale 2
The scale 20 is supported by the guide groove 42 so as to be movable in the longitudinal direction.

As in the first embodiment (see FIG. 3),
The light source section 32 has two light emitting elements, for example, vertical cavity surface emitting lasers 32a and 32b, and the light detecting section 34 has two light receiving elements so that the moving direction can be detected in addition to the moving amount of the scale 20. For example, the photodiodes 34a and 34
b, vertical cavity surface emitting lasers 32a and 32
The interval between the light emitting surfaces 2b is set to a length obtained by adding a quarter of the pitch to a positive multiple of the pitch of the scale 20 pattern.

The surfaces of the light source 32 and the light detector 34 and the surface of the scale 20 are arranged non-parallel so that light from the light source 32 is reflected by the scale 20 to the light detector 34. The angle between them is 5 to 40 degrees, preferably 10 to 25 degrees. Vertical cavity surface emitting laser 3
The dimensions of the light emitting surfaces of 2a and 32b are preferably 100 μm ×
It is 100 μm or less. The width of the scale 20 is 200 μm
10 to 10 mm, preferably 1 to 5 mm,
The thickness is 50 μm to 5 mm, preferably 200 μm
１1 mm. The distance between the light source 32 and the scale 20 is
The pitch is determined depending on the pitch of the pattern provided on the scale 20 and the inclination angle between the surface of the light source unit 32 and the surface of the scale 20 so that the reflected light from the scale 20 can be favorably incident on the light detection unit 34. It is 0.1 mm to 2 mm, preferably 0.2 mm to 0.7 mm.

As shown in FIG. 9, both ends of the scale 20 are fixed to a fixed portion 56, and the fixed portion 56 is fixed to, for example, the moving portion 204 of the linear stage 200 shown in FIG. As shown in FIGS. 9 and 10, the detection head 30 is attached to a fixing jig 54 via a displacement actuator 62, and the displacement actuator 6
2 supports the fixing jig 54 so as to be movable in the X and Y directions. The displacement actuator 62 has, for example, a voltage-driven piezoelectric element, or has a current-driven electromagnetic coil. The fixing jig 54 is fixed to, for example, the fixing portion 202 of the linear stage 200 shown in FIG. The displacement actuator 62 is driven by a feedback circuit 66 in accordance with an instruction from the signal processing circuit 64.

The optical linear encoder changes the distance between the light source unit 32 and the scale 20, in other words, the scale 2
It has an interval variation detection sensor for detecting variation in the gap between the zero and the guide groove 42. The interval variation detection sensor includes, for example, a flat electrode provided on the scale 20, a contact provided on the holding member 40, and a signal processing circuit 64 for checking electrical contact / non-contact between the two. It is configured. Hereinafter, the interval variation detection sensor having this configuration will be described.

As shown in FIG. 12, the scale 20 has a band-shaped membrane electrode 2 extending in the longitudinal direction on its upper surface 20b.
2 and a strip-shaped membrane electrode 24 extending in the longitudinal direction on the side surface 20c. These membrane electrodes 22 and 24 are produced, for example, by vacuum evaporation or sputtering, or by attaching a conductive tape.

As shown in FIG. 11, on the upper surface 42b of the guide groove 42, there are provided a contact 72 which protrudes largely toward the membrane electrode 22 provided on the upper surface of the scale 20, and a contact 74 which protrudes less. On the side surface 42c, there are provided a contact member 76 protruding largely toward the membrane electrode 24 provided on the side surface of the scale 20, and a contact member 78 protruding less. These contacts 72, 74, 76 and 78
Is the elastic displacement coefficient (displacement when force is applied / applied force)
Of a conductive material having a thickness of, for example, 50 to 500
It is made of a plate-like aluminum alloy, plate-like copper, and plate-like stainless steel of about μm.

The initial position of the scale 20 with respect to the holding member 40 is determined as follows. The lower surface 20a of the scale 20 is in contact with the lower surface 42a of the guide groove 42, and the relative position of the scale 20 in which the distance between the side surface 20c of the scale 20 and the side surface 42c of the guide groove 42 facing the scale 20 is a predetermined distance is defined as the initial position. I do. In this initial position, the upper surface 20 of the scale 20
The distance between b and the upper surface 42b of the guide groove 42 is a predetermined distance, in other words, the distance between the light source 32 and the scale 20 is a predetermined distance.

In the initial position, the contact 72 is
2, but the contact 74 is separated from the membrane electrode 22. The movement of the scale 20 in the + X direction from the initial position with respect to the holding member 40 causes the membrane electrode 22 and the contact 74 to contact. Conversely, -X from the initial position of the scale 20
The movement in the direction is restricted by the lower surface 42a of the guide groove 42. The signal processing circuit 64 includes the membrane electrode 22 and the contact 7
4 is being checked for contact / non-contact, and the feedback circuit 6
6 is for detecting contact between the membrane electrode 22 and the contact 74.
The displacement actuator 62 is driven to move the holding member 40, that is, the detection head 30 in the + X direction.

In the initial position, the contact 76 is in contact with the membrane electrode 24, but the contact 78 is apart from the membrane electrode 24. The movement of the scale 20 in the + Y direction from the initial position with respect to the holding member 40 is performed by the membrane electrode 24 and the contact 7.
The movement of the scale 20 from the initial position in the −Y direction causes the contact between the membrane electrode 24 and the contact 78. The signal processing circuit 64 examines the contact / non-contact between the membrane electrode 24 and the contact 76 and the contact / non-contact between the membrane electrode 24 and the contact 78. The feedback circuit 66
4 and the contact 76 are not contacted with each other.
That is, the displacement actuator 62 is driven to move the detection head 30 in the + Y direction, and the holding member 40, that is, the detection head 30 is moved in the −Y direction with respect to the detection of the contact between the membrane electrode 24 and the contact 78. The displacement actuator 62 is driven.

By this control, a change in the relative position between the scale 20 and the holding member 40 is compensated, and the scale 2
0 is always kept at the initial position. That is, the distance between the light source 32 and the scale 20 is always kept constant. Therefore, the amount of movement of the scale 20 with respect to the detection head 30 can be measured with high accuracy.

Various modifications and changes can be made to this embodiment. For example, the interval variation detection sensor is a scale 2
0, a flat electrode provided on the holding member 40 facing the flat electrode, and a signal processing circuit 64 for examining a change in capacitance between the two. Good. Hereinafter, the interval variation detection sensor having this configuration will be described.

As shown in FIG. 13, a band-shaped membrane electrode 22 extending in the longitudinal direction is provided on the upper surface 20b of the scale 20, and a band-shaped membrane electrode 24 extending in the longitudinal direction is provided on the side surface 20c. I have. A flat counter electrode 82 facing the membrane electrode 22 provided on the upper surface 20b of the scale 20 is provided on an upper surface 42b of the guide groove 42, and a side surface 42c of the scale 20 is provided on a side surface 42c of the guide groove 42. A plate-like counter electrode 84 facing the membrane electrode 24 provided in 20c is provided.

The movement of the scale 20 in the + X direction from the initial position is caused by the capacitance C between the membrane electrode 22 and the counter electrode 82.
Increment 1. The signal processing circuit 64 measures the capacitance C1 between the membrane electrode 22 and the counter electrode 82, and the feedback circuit 66 sets the holding member 40, that is, the detection head 30 to + X in response to the increase in the capacitance C1. The displacement actuator 62 is driven to move in the direction.

Further, + Y from the initial position of the scale 20
The movement in the direction reduces the capacitance C2 between the membrane electrode 24 and the counter electrode 84, while the movement in the -Y direction from the initial position of the scale 20 decreases the capacitance C2 between the membrane electrode 24 and the counter electrode 84.
The capacitance C2 during the period is increased. Signal processing circuit 64
Measures the capacitance C2 between the membrane electrode 24 and the counter electrode 84. The feedback circuit 66 has a capacitance C2
Is detected, the displacement actuator 62 is driven to move the detection head 30 in the -Y direction, and the detection head 30 is moved to + Y in response to the detection of the increase in the capacitance C2.
The displacement actuator 62 is driven to move in the direction.

By this control, the scale 20 is always kept at the initial position, and the distance between the light source 32 and the scale 20 is always kept constant. Therefore, the amount of movement of the scale 20 with respect to the detection head 30 can be measured with high accuracy.

The displacement actuator 62 may include a variable power mechanism for amplifying the displacement of the displacement generating element. FIG.
The displacement actuator 62 includes a displacement generating element for generating a displacement in the X direction, for example, a laminated piezoelectric element 86, a displacement generating element for generating a displacement in the Y direction, for example, a laminated piezoelectric element 88, and a scaling mechanism. And a two-dimensional notched hinge leaf spring mechanism 90. Detection head 30
Is fixed to the mounting portion 92 of the two-dimensional notched hinge leaf spring mechanism 90, and the displacement generated by the laminated piezoelectric element 86 or the laminated piezoelectric element 88 is amplified and transmitted to the mounting portion 92. The two-dimensional notched hinge leaf spring mechanism 90 is manufactured by, for example, wire electric discharge machining using a material of ceramics, stainless steel, phosphor bronze, an aluminum alloy, or the like, preferably an alloy of phosphor bronze and aluminum.

[Fourth Embodiment] An optical linear encoder according to a fourth embodiment will be described with reference to FIGS. In the figure, members already mentioned in the description of the above embodiment are indicated by the same reference numerals,
In the following description, the detailed description is omitted.

As shown in FIG. 15, the optical linear encoder has a scale 20 and a detection head 30. The scale 20 is made of a rigid and elongated plate material, for example, a glass plate, and has an optically detectable pattern, for example, a light and dark pattern having a large number of thin strip-shaped reflectors arranged at a constant pitch in the longitudinal direction.

The detection head 30 has a pattern detection sensor for detecting the movement of the pattern on the scale 20.
The pattern detection sensor has a light source unit 32 that emits light toward the scale 20 and a light detection unit 34 that detects light reflected from the scale 20. As in the first embodiment (see FIG. 3), the light source unit 32 has two light emitting elements, for example, a vertical cavity surface emitting laser so that the direction of movement can be detected in addition to the amount of movement of the scale 20. The photodetector 34 has two light receiving elements, for example, photodiodes, and the interval between the light emitting surfaces of the two vertical cavity surface emitting lasers is four times the pitch of the scale 20 pattern. It is set to the length plus one part.

The light source section 32 and the light detection section 34 are bonded to a heat dissipation and wiring board 36. Light source unit 32 and light detection unit 34
Can be made in a monolithic fashion or can be made separately and lined up during assembly. Further, a transparent glass substrate 102 is adhered to the front surfaces of the light source unit 32 and the light detection unit 34 for reinforcing the strength. The glass substrate 102 is bonded to the flexible wiring substrate 104, and the light source 32 is
6 and the photodetector 34 is connected to the flexible wiring board 104 via the wiring 108. The flexible wiring board 104 is, for example, a polyimide flexible wiring board. Preferably, the light-transmitting portion of the bonding portion of the glass substrate 102 is good, and the other portions have flexibility. Light source 3
Adhesive having high light transmittance is used for bonding between the photodetector 2, the photodetector 34, the glass substrate 102, and the flexible wiring substrate 104.

The sealing material 116 is made of the flexible wiring board 1
4, the light source unit 32, the light detection unit 34, the heat dissipation / wiring board 36, the glass substrate 102, the wiring 106, and the wiring 10
8 is sealed. The material of the sealing material 116 is, for example, a photocurable liquid resin, which is cured by, for example, irradiation of ultraviolet rays. Another material of the sealing material 116 is, for example, silicone oil.

The sealing member 116 is attached to a fixing jig 120 via an elastic deformation member 118. The elastic deformation body 118 is made of ordinary rubber, silicone rubber, a coil spring,
It is composed of a parallel leaf spring or the like, which is fixed to the fixing jig 120 by, for example, bonding.

Two types of protrusions 112 and 114 having different lengths are attached to the flexible wiring board 104. The protruding portions 112 and 114 have a scale 2
By contacting with zero, a certain distance is secured between the detection head 30 and the scale 20.

The detection head 30 and the scale 20 are arranged such that the projections 112 and 114 are both in contact with the scale 20. Due to the difference in the length of the projections 112 and 114, the surfaces of the light source unit 32 and the light detection unit 34 and the surface of the scale 20 are arranged non-parallel, so that light from the light source unit 32 is The light is well reflected to the light detection unit 34. In other words, the lengths of the protrusions 112 and 114 are different so that the light from the light source 32 is reflected well by the scale 20 to the light detector 34, and the lengths of the protrusions 112 and 114 are different. Is selected such that the angle between the surface of the light source 32 and the surface of the scale 20 is 5 to 40 degrees, preferably 10 to 25 degrees.

The detection head 30 is urged toward the scale 20 by the elastic deformation member 118. Fixing jig 1
A change in the position of the scale 20 in the X direction with respect to the position 20 is absorbed by the elastic deformation body 118. Therefore, the contact between the scale 20 and the protrusions 112 and 114 is always maintained regardless of the relative position change of the scale 20 in the X direction. As a result, the light source unit 32 and the scale 2
The interval of 0 is always kept constant. Therefore, the detection head 3
The movement amount of the scale 20 with respect to 0 can be measured with high accuracy.

Various modifications and changes can be made to this embodiment. For example, the pattern detection sensor is a scale 2
It may be composed of a composite resonator type displacement sensor having 0 as an external mirror. Hereinafter, the detection head 30 having this configuration will be described.

As shown in FIG. 16, a vertical cavity surface emitting laser 32 serving as a light source unit and a photodiode 34 serving as a light detecting unit are stacked, and this composite is a composite using the scale 20 as an external mirror. This constitutes a resonator type displacement sensor. In this composite resonator type displacement sensor, the light emitted from the light source 32 is modulated by the intensity and phase of the light reflected from the scale 20. The intensity of the light emitted from the light source unit 32 is determined by the light detection unit 34 disposed on the back side thereof.
Is detected by A plurality of protrusions 122 having the same length are fixed to the flexible wiring board 104. As a result, the light exit surface of the light source 32 and the surface of the scale 20 are arranged in parallel, and the distance between the two is kept constant by maintaining the contact between the protrusion 122 and the scale 20 by the elastically deformable body 118.

[Fifth Embodiment] An optical linear encoder according to a fifth embodiment will be described with reference to FIGS. 17 and 18. FIG. In the figure, members already mentioned in the description of the above embodiment are indicated by the same reference numerals,
In the following description, the detailed description is omitted.

As shown in FIG. 17, the detection head 30
Is fixed to the fixing jig 120 via the driving mechanism 132, and the detection head 30
It is movably supported in the direction. The drive mechanism 132 has a displacement generating element that generates a displacement in response to an input electric signal. The displacement generating element is, for example, a voltage-driven piezoelectric element or a current-driven electromagnetic coil. The displacement generating element may be of any type as long as it generates a displacement with respect to an input electric signal. Further, the drive mechanism 132 may have a variable power mechanism for amplifying the displacement of the displacement generating element. The variable power mechanism is, for example, a two-dimensional notched hinge leaf spring.

As shown in FIG. 18, the scale 20 has a strip-shaped electrode 26 extending in the longitudinal direction and a light-dark pattern 28 composed of a number of narrow strip-shaped reflectors arranged at a constant pitch in the longitudinal direction. ing.

The optical linear encoder has a light source 3
An interval variation detection sensor for detecting a variation in the interval between the scale 2 and the scale 20 is provided. This interval variation detection sensor is shown in FIG.
7, the electrode 26 provided on the scale 20, the electrode 134 provided on the flexible wiring board 104 facing the electrode 26, and the signal processing circuit 136 for detecting a change in capacitance between the electrode 26 and the electrode 134. Be composed. The interval change detection sensor is not limited to this configuration, and may be any sensor that can detect a change in the interval between the light source unit 32 and the scale 20. As an example, there is a configuration for detecting magnetic information between the scale 20 and the wiring board 104.

The feedback circuit 136 is driven so as to compensate for the change in the capacitance between the electrode 26 and the electrode 134 detected by the signal processing circuit 134, in other words, to keep the capacitance constant. The mechanism 132 is controlled. By this control, the distance between the light source 32 and the scale 20 is always kept constant. Therefore, the amount of movement of the scale 20 with respect to the detection head 30 can be measured with high accuracy.

[Sixth Embodiment] An optical linear encoder according to a fifth embodiment will be described with reference to FIGS. In the figure, members already mentioned in the description of the above embodiment are indicated by the same reference numerals,
In the following description, the detailed description is omitted.

As shown in FIG. 19, the detection head 30
Is X with respect to the fixing jig 120 by the driving mechanism 132.
It is movably supported in the direction. The drive mechanism 132 has a displacement generating element that generates a displacement in response to an input electric signal. The displacement generating element may be of any type as long as it generates a displacement with respect to an input electric signal. Further, the drive mechanism 132 may have a variable power mechanism for amplifying the displacement of the displacement generating element.

As shown in FIG. 21, the scale 20 has a strip-shaped reflector 210 extending in the longitudinal direction and a light-dark pattern 212 composed of a number of narrow strip-shaped reflectors arranged at a constant pitch in the longitudinal direction. doing.

This optical linear encoder has an interval variation detection sensor for optically detecting a variation in the interval between the detection head 30 and the scale 20. The interval variation detection sensor is, for example, a reflection plate 210 provided on the scale 20.
(Shown in FIG. 21), a light source unit 142 (shown in FIGS. 19 and 20) for irradiating the light
The light receiving unit 144 (FIG. 1) that receives the light beam reflected by
9 and FIG. 20), and a signal processing circuit 146 (shown in FIG. 19) for processing a signal from the light receiving section 144. The interval change detection sensor is not limited to this configuration, and may be any sensor that can detect a change in the interval between the detection head 30 and the scale 20.

The light source section 142 is, for example, a vertical cavity surface emitting laser, and the light receiving section 144 is, for example, a position detecting element (PSD) 1 for outputting a signal corresponding to the incident position of the light beam.
44. As the light receiving section 144, any element that outputs a signal according to the incident position of the light beam can be applied. For example, the position detection element (PSD) 144
Instead, a photodiode having a plurality of divided light receiving regions may be used.

As shown in FIG. 20, the surface emitting laser 1
The light beam emitted from 42 is reflected by the reflecting plate 210 of the scale 20, enters the position detecting element 144, and forms a light spot 150 on its light receiving surface. The incident position of the light beam, that is, the position of the light spot 150 is determined by the detection head 30.
And the distance of the scale 20. The signal output from the signal processing circuit 146 reflects the position of the light spot 150, and thus the detection head 30 and the scale 20
Reflects the fluctuation of the interval.

The feedback circuit 148 controls the driving mechanism 132 based on the signal from the signal processing circuit 146 so as to compensate for a change in the position of the light spot 150, in other words, to keep the incident position of the light beam at an appropriate position. Control. By this control, the distance between the light source 32 and the scale 20 is always kept constant. Therefore, the amount of movement of the scale 20 with respect to the detection head 30 can be measured with high accuracy.

Various modifications and changes can be made to the present embodiment. For example, the pattern detection sensor and the interval fluctuation detection sensor may be configured by a composite resonator type displacement sensor using the scale 20 as an external mirror. Hereinafter, the detection head 30 having this configuration will be described.

As shown in FIGS. 22 and 23, the light source section 32 constituting the pattern detection sensor is, for example, a vertical cavity surface emitting laser, and the light detecting section 34 is, for example, a photodiode. The surface emitting laser 32 and the photodiode 34 are stacked to constitute a composite resonator type displacement sensor using the light and dark pattern 212 of the scale 20 as an external mirror. The intensity of light emitted from the surface-emitting laser 32 changes according to the intensity of light reflected from the light-dark pattern 212 of the scale 20, and is detected by a photodiode 34 disposed on the back side of the surface-emitting laser 32.

Light source unit 14 constituting interval fluctuation detecting sensor
Reference numeral 2 denotes, for example, a vertical cavity surface emitting laser,
Reference numeral 44 denotes, for example, a photodiode, and the vertical cavity surface emitting laser 142 and the photodiode 144 are stacked to form a composite resonator type displacement sensor using the reflection plate 210 of the scale 20 as an external mirror. Surface emitting laser 1
The intensity of the light emitted from the reflector 42 of the scale 20
It changes according to the distance to 0, and is detected by the photodiode 144 arranged on the back side of the surface emitting laser 142.

The signal processing circuit 146 and the feedback circuit 148 cooperate to control the driving mechanism 132 so as to keep the output of the photodiode 144 constant. With this control, the interval between the detection head 30 and the scale 20 is always kept constant. Therefore, the scale 20 with respect to the detection head 30
Can be measured with high accuracy.

The present invention is not limited to the above-described embodiment, but includes all implementations without departing from the subject matter. That is, the above-described embodiment can be subjected to various modifications, but all such modifications are within the scope of the technical idea of the present invention.

The present invention includes the technical ideas described in the following sections. 1. [Configuration] a detection head having a light source unit and a light detection unit;
A plate-like scale having an optically detectable pattern and movable with respect to the detection head, and measuring the distance of movement of the scale with respect to the detection head by reading the pattern of the scale with the detection head The optical linear encoder further includes a support portion that slidably supports the scale, and a pressing member that presses the scale in a direction independent of its movement direction to bring the scale into close contact with the support portion. Optical linear encoder.

[Corresponding Embodiments] The first and second embodiments correspond to each other. The “light source unit” is a vertical cavity surface emitting laser in the embodiment, but includes other surface emitting lasers, edge emitting lasers, LEDs, and the like. The “light detector”
In the embodiment, the photodiode is used, but other photoelectric conversion devices are also included.

[Operation and Effect] Since the scale is pressed by the pressing member in a direction independent of the moving direction (preferably in a direction perpendicular to the moving direction) and is closely attached to the supporting portion, the distance between the light source portion and the scale is always constant. Be kept constant. Therefore,
There is no need to readjust the position between the light source unit and the scale during use. As a result, the number of optical elements is small,
An optical encoder with high measurement accuracy is provided.

2. [Structure] The optical linear encoder according to item 1, further comprising a support mechanism for supporting the detection head movably in a direction perpendicular to the moving direction of the scale.

[Corresponding Embodiment] The second embodiment corresponds to the second embodiment. [Operation and Effect] In use, the scale is fixed to the moving part of the object to be measured (for example, a linear stage), and the detection head is mounted via a support mechanism that movably supports the measuring head in a direction perpendicular to the moving direction of the scale. It is fixed to the fixed part of the measurement object. The optical linear encoder measures the amount of movement of the movable part with respect to the fixed part by detecting the change in brightness of reflected light from the scale fixed to the movable part by the detection head fixed to the fixed part. Variations in the distance of the moving part relative to the fixed part in a direction perpendicular to its desired movement direction, which may occur while the moving part moves relative to the fixed part, are absorbed by the support mechanism. Therefore, the distance between the light source unit and the scale is kept constant irrespective of the change in the distance between the moving unit and the fixed unit, and the measurement result is not affected by this change.

3. [Configuration] A detection head having a light source unit and a light detection unit, and a plate-like scale having an optically detectable pattern and movable with respect to the detection head. In an optical linear encoder that measures the distance the scale moves relative to the detection head by reading the pattern, a projection that contacts the scale to secure a certain distance between the detection head and the scale, and directs the detection head toward the scale An optical linear encoder, further comprising: an elastic member for biasing.

[Corresponding Embodiment] The fourth embodiment corresponds to the fourth embodiment. [Operation and Effect] The detection head is urged toward the scale by the elastic member, the protrusion comes into contact with the scale to secure a certain distance between the scale and the detection head, and the scale slides on the protrusion. I do. Therefore, the distance between the light source unit and the scale is always kept constant. Thereby, a small-sized optical encoder with high measurement accuracy is realized.

4. [Configuration] A detection head having a light source unit and a light detection unit, and a plate-like scale having an optically detectable pattern and movable with respect to the detection head. In an optical linear encoder that measures a moving distance of a scale with respect to a detection head by reading a pattern, an interval fluctuation detecting unit that detects a fluctuation of an interval between a light source unit and a scale, and a detection head based on the detected fluctuation of the interval. An optical linear encoder further comprising interval control means for moving the light source unit and the scale to keep the interval constant.

[Corresponding Embodiment] The third embodiment corresponds to the third embodiment. [Operation and Effect] The interval variation detecting means detects a variation in the interval between the light source unit and the scale, and the interval control means compensates for the variation based on the detected variation in the interval. Move the detection head to keep it constant. With this control, the distance between the light source unit and the scale is always kept constant. As a result, a compact optical encoder with high measurement accuracy is realized.

5. 4. The optical linear encoder according to claim 4, wherein the distance control means includes a displacement actuator. [Corresponding Embodiment] The third embodiment corresponds to the third embodiment.

[Operation and Effect] The distance control means uses the displacement actuator to move the detection head so as to compensate for the fluctuation in the distance between the light source unit and the scale detected by the distance fluctuation detecting means. With this control, the distance between the light source unit and the scale is always kept constant. As a result, a compact optical encoder with high measurement accuracy is realized.

6. [Structure] In the optical linear encoder according to the fifth aspect, the distance control means further includes a magnification changing mechanism for changing the displacement of the displacement actuator. [Corresponding Embodiment of the Invention] The third embodiment corresponds to the third embodiment.

[Operation and Effect] The displacement of the displacement actuator is enlarged by the variable power mechanism and transmitted to the detection head. For this reason, the detection head can move in a range exceeding the movable range of the displacement actuator. Therefore, it is possible to cope with a large variation in the distance between the light source unit and the scale that exceeds the movable range of the displacement actuator.

7. [Structure] An optical linear encoder according to item 6, wherein the variable power mechanism includes a notched leaf spring. [Corresponding Embodiment of the Invention] The third embodiment corresponds to the third embodiment.

[Operation and Effect] Since the notched hinge leaf spring has a simple structure, it can be manufactured in a small size. Therefore, the variable power mechanism is realized by a small structure. As a result, it is possible to obtain a small-sized optical linear encoder capable of coping with a large variation in the distance between the light source unit and the scale exceeding the movable range of the displacement actuator.

8. [Configuration] In the fourth aspect, the interval variation detecting means includes a flat electrode provided on one of the detection head and the scale, and a large projection protruding toward the flat electrode provided on the other of the detection head and the scale. The first contact, the second contact that protrudes less, the presence or absence of electrical contact between the flat electrode and the first contact, and the electrical contact between the flat electrode and the second contact. Contact detecting means for detecting the presence or absence of a non-contact, the interval control means, the electrical contact between the plate-shaped electrode and the first contact and the plate-shaped electrode and the second contact An optical linear encoder characterized by moving a detection head so as to maintain electrical non-contact of the optical linear encoder.

[Corresponding Embodiment of the Invention] The third embodiment corresponds to the third embodiment. [Operation and Effect] For example, a flat electrode is provided on a scale, and a contact is provided on a detection head. The contact detecting means is configured to detect an electrical contact between the flat electrode and the first contactor.
Non-contact, electrical contact between flat electrode and second contactor /
Detect non-contact. The interval control means moves the detection head based on the information detected by the contact detection means, to make electrical contact between the plate-shaped electrode and the first contact, and between the plate-shaped electrode and the second contact. Maintain electrical non-contact with the With this control, the distance between the light source unit and the scale is always kept constant. As a result, the movement of the scale with respect to the detection head is measured with high accuracy.

9. [Configuration] In the fourth aspect, the interval variation detecting means includes: a first plate-shaped electrode provided on the detection head; a second electrode provided on the scale, the second electrode facing the first electrode; And capacitance change detecting means for detecting a change in capacitance between the second electrode and the second electrode, and the interval control means moves the detection head so as to compensate for the detected change in capacitance. An optical linear encoder, characterized in that:

[Corresponding Embodiment of the Invention] The third and fifth embodiments correspond to each other. [Operation and Effect] Each of the scale and the detection head is provided with a flat electrode facing each other. The capacitance fluctuation detecting means detects the fluctuation of the capacitance between these two electrodes, and the interval control means compensates for the fluctuation of the detected capacitance, that is, keeps the capacitance constant. Move the detection head to keep it. With this control, the distance between the light source unit and the scale is always kept constant. As a result, the movement of the scale with respect to the detection head is measured with high accuracy.

10. [Arrangement] In the optical linear encoder according to the fourth aspect, the interval fluctuation detecting means includes an interval measuring means for optically measuring an interval between the light source unit and the scale.

[Corresponding Embodiment of the Invention] The sixth embodiment corresponds to the sixth embodiment. [Operation and Effect] The distance measuring means optically measures the distance between the light source unit and the scale, and the distance controlling means moves the detecting head so as to keep the distance measured by the distance measuring means constant. With this control, the distance between the light source unit and the scale is always kept constant. As a result, the movement of the scale with respect to the detection head is measured with high accuracy.

11. [Structure] An optical linear encoder according to Item 10, wherein the distance measuring means includes a distance sensor comprising a vertical cavity surface emitting laser and a position detecting optical element.

[Corresponding Embodiment of the Invention] The sixth embodiment corresponds to the sixth embodiment. [Operation and Effect] The distance measuring means uses a distance sensor composed of a vertical cavity surface emitting laser and a position detecting optical element,
Measure the distance between the light source and the scale. Therefore, the distance between the light source unit and the scale is measured with high accuracy. This allows
The distance between the light source and the scale is kept constant with high accuracy.
As a result, the movement of the scale with respect to the detection head is measured with high accuracy.

12. [Structure] An optical linear encoder according to Item 10, wherein the interval measuring means includes a complex resonance interference sensor including a vertical cavity surface emitting laser and a photodiode.

[Corresponding Embodiment of the Invention] The sixth embodiment corresponds to the sixth embodiment. [Operation and Effect] The distance measuring means measures the distance between the light source unit and the scale by using a composite resonance interference sensor comprising a vertical cavity surface emitting laser and a photodiode. Therefore, the distance between the light source unit and the scale is measured with high accuracy.
Thereby, the distance between the light source unit and the scale is kept constant with high accuracy. As a result, the movement of the scale with respect to the detection head is measured with high accuracy.

[0101]

According to the present invention, there is provided an optical linear encoder in which the distance between the light source unit and the scale is always kept constant, and therefore the amount of movement of the scale with respect to the detection head can be measured with high accuracy.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical linear encoder according to a first embodiment.

FIG. 2 is a partial sectional perspective view of the optical linear encoder shown in FIG.

FIG. 3 is an enlarged view of a light source unit, a light detection unit, and a scale in the optical linear encoder of FIG.

FIG. 4 is an enlarged cross-sectional view of a scale and a guide groove in the optical linear encoder of FIG. 1;

FIG. 5 is an enlarged view showing a scale and a guide groove in a modification of the optical linear encoder of FIG. 1;

FIG. 6 is a schematic perspective view of a linear stage to which the optical linear encoder of FIG. 1 is attached.

FIG. 7 is a side sectional view of an optical linear encoder according to a second embodiment.

8 is a partial sectional plan view of the optical linear encoder shown in FIG.

FIG. 9 is a partial cross-sectional plan view of an optical linear encoder according to a third embodiment.

FIG. 10 is a side sectional view of the optical linear encoder shown in FIG. 9;

FIG. 11 is a diagram showing a configuration of an interval fluctuation detection sensor in the optical linear encoder of FIGS. 9 and 10;

FIG. 12 shows a side surface and a plane of a scale in the optical linear encoder of FIGS. 9 and 10;

FIG. 13 is a diagram showing a configuration of another interval fluctuation detection sensor applicable to the optical linear encoder of FIGS. 9 and 10;

14 shows a two-dimensional notched hinge leaf spring mechanism which is a variable power mechanism that can be incorporated in the displacement actuator shown in FIG.

FIG. 15 is a side sectional view of an optical linear encoder according to a third embodiment.

FIG. 16 is a side sectional view of a modified example of the optical linear encoder of FIG. 15;

FIG. 17 is a side sectional view of an optical linear encoder according to a fourth embodiment.

FIG. 18 is a partial plan view of the scale shown in FIG. 17;

FIG. 19 is a side sectional view of an optical linear encoder according to a fifth embodiment.

20 is a perspective view schematically showing a pattern detection sensor and an interval fluctuation detection sensor in the optical linear encoder of FIG.

FIG. 21 is a partial plan view of the scale shown in FIG. 19;

FIG. 22 is a side sectional view of a modified example of the optical linear encoder of FIG. 19;

23 is a perspective view schematically showing a pattern detection sensor and an interval fluctuation detection sensor in the optical linear encoder of FIG.

[Explanation of symbols]

 Reference Signs List 20 scale 30 detection head 32 light source section 34 light detection section 40 holding member 42 guide groove 44 leaf spring

Claims (3)

[Claims] A detection head having a light source unit and a light detection unit;
A plate-like scale having an optically detectable pattern and movable with respect to the detection head, and measuring the distance of movement of the scale with respect to the detection head by reading the pattern of the scale with the detection head An optical linear encoder, further comprising: a support portion that slidably supports the scale; and a pressing member that presses the scale in a direction independent of its movement direction to bring the scale into close contact with the support portion. Optical linear encoder. A detection head having a light source unit and a light detection unit;
A plate-like scale having an optically detectable pattern and movable with respect to the detection head, and measuring the distance of movement of the scale with respect to the detection head by reading the pattern of the scale with the detection head In the optical linear encoder, it is preferable that the optical linear encoder further includes a protrusion that abuts on the scale to secure a fixed distance between the detection head and the scale, and an elastic member that urges the detection head toward the scale. Features an optical linear encoder. A detection head having a light source unit and a light detection unit;
A plate-like scale having an optically detectable pattern and movable with respect to the detection head, and measuring the distance of movement of the scale with respect to the detection head by reading the pattern of the scale with the detection head In an optical linear encoder, an interval variation detecting means for detecting a variation in the interval between the light source unit and the scale, and an interval control for moving the detection head based on the detected variation in the interval to maintain a constant interval between the light source unit and the scale. An optical linear encoder further comprising means.