JPH0882533A - Light source module and displacement measuring device using module thereof - Google Patents

Abstract

PURPOSE: To provide a light source module, wherein the light source can be replaced quickly and simply from the outside without removing an encoder and the like from a control system when the trouble caused by the light source has occurred in the device such as the encoder, and a displacement measuring devide using the module thereof. CONSTITUTION: A light emitting element 4 and a first collimator lens 3 constitute a light source unit 1, which emits the luminous flux of parallel plane waves. The light source unit 1 and a second collimator lens 2, which is fixed to the specified position of an encoder, constitute a light source module. The second collimator lens 2 converts the luminous flux of the parallel plane waves into the converging or diverding luminous flux. The light source 1 can be attached, removed and replaced to and from the light source module as a unitary body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source module and a displacement measuring device using the same, and can be suitably applied to a light source portion of a measuring instrument, information equipment or the like which uses a luminous flux from a light source such as a laser. is there.

[0002]

2. Description of the Related Art At present, measuring instruments and information devices having a laser as a light source are widely used. For example, in a displacement measuring device such as a rotary encoder, displacement information of an object is detected by utilizing a light modulating action of an optical grating.

FIG. 4 is a schematic view of a main part of a conventional rotary encoder using a semiconductor laser as a light source. In the figure, 4 is a semiconductor laser, 20 is a collimator lens, 21 is a polarization beam splitter having a polarization plane 22 built therein, 25 is a prism, 26 is a 1/4 wavelength plate, 6 is a reflecting member, 28 is a 1/4 wavelength plate, Reference numeral 29 is a light splitting element, 30 and 31 are polarizing plates, and 8 is a light receiving sensor. Reference numeral 5 is a radiation diffraction grating (optical grating) formed on a transparent disk (scale) 40 fixed to the object to be measured. When two same members are used, they are distinguished by adding a and b.

The operation of the conventional rotary encoder will be described with reference to FIGS. 4 (A) and 4 (B). In the figure, the light beam emitted from the semiconductor laser 4 is changed by the collimator lens 20 into a light beam which is converged at a predetermined position, and after entering the polarization beam splitter 21, the reflected light beam 23 and the transmitted light beam 24 having a substantially equal amount of light are polarized by the polarization plane 22. It is divided into two linearly polarized light beams.

The two split light beams are reflected twice in the polarization beam splitter 21, respectively, and then are deflected downward by the prism 25 to positions M1 and M2 on the radiation diffraction grating 5.
Incident on. Then, of the transmitted diffracted light generated by the radiation diffraction grating 5, only the diffracted light of a specific order is reflected by the reflecting member 6, again enters the positions M1 and M2, and is diffracted. Then, the diffracted light of a specific order travels backwards through the paths of the light flux 23 and the light flux 24, and is combined by the polarization plane 22 to become a light flux 27. It is incident on the sensors 8a and 8b.

With the above configuration, if the specific orders selected at the positions M1 and M2 of the radiation diffraction grating 5 are m and n, respectively, the rotational displacement of one pitch of the radiation diffraction grating 5 causes the light receiving sensor (2 m -2n) sinusoidal waveforms are obtained. For example, when m = 1 and n = −1, four sine wave signals are obtained by rotational displacement of the radiation diffraction grating 5 for one pitch, and rotation amount detection can be performed with high resolution.

FIG. 4C is a sectional view of the rotary encoder body. In the figure, 32 is a main substrate, 33 is a main body cover, 34 is a bearing unit, and 35 is a rotating shaft, which is connected to a rotating object of the object to be measured.

The encoder using such a semiconductor laser as a light source is expanding its application in the field of high precision and precision control technology requiring a resolution of submicron unit. In such a field, it is common that the encoder is continuously energized as a condition of use, and therefore, it is necessary to design the semiconductor laser in consideration of life reliability.

Factors that define the life of the semiconductor laser include bulk deterioration, reflection surface deterioration, and light-emitting end face destruction due to surge. If such a factor causes a failure in the encoder function, In such a case, quick recovery action is necessary because the entire control system is immediately affected.

[0010]

When a failure due to such a light source occurs during operation of the encoder, conventionally, the encoder main body is once removed from the motor drive unit, and the encoder cover 33 is removed. I had to replace a semiconductor laser and re-adjust the optical and electrical settings.

In the configuration of the conventional example, the distance between the semiconductor laser 4 and the collimator lens 20 and the position of the light emitting point on the optical axis are adjusted by adjusting the position of the light beam incident on the light receiving sensor 8 and its shape change, and further by changing the shape of the radiation diffraction grating 5. 2 via position M1, M2
This is done directly on the encoder body by checking the contrast of the sine wave signal by adjusting the one-color degree of the light flux.

For example, FIG. 5 is an explanatory view of a situation in which the shape of the light beam incident on the effective area portion 9 of the light receiving sensor changes due to the gap error between the semiconductor laser 4 and the collimator lens 20. FIG. 5 (A) shows a case where the reference position is adjusted correctly, and the luminous flux 100 with respect to the effective area portion 9 of the light receiving sensor.
Are approximately equal in area and overlap. In contrast,
When the distance deviates from the reference position by ± 20 μm, the shape of the light flux 100 changes greatly as shown in FIGS. 5 (B) and 5 (C), respectively, and largely protrudes from the effective area portion 9 of the light receiving sensor, or remarkably. It becomes smaller, the amplitude of the sine wave signal from the sensor becomes smaller, or the signal is distorted.

Therefore, in the case of the conventional example, the mutual adjustment of the position of the semiconductor laser 4 and the collimator lens 20 requires high accuracy. Therefore, if a failure due to the light source occurs during the operation of the encoder, the encoder main body is controlled in the control system. It is actually extremely difficult to replace only the light source and remove the cover without removing the cover while it is still connected to the motor drive unit, until the encoder and the control system including it are restarted. Needed a lot of time.

The present invention uses a light source module and a light source module capable of performing quick and simple light source replacement from the outside without removing the encoder or the like from the control system system when a failure due to the light source occurs in a device such as an encoder. It is intended to provide a displacement measuring device.

[0015]

The light source module according to the present invention comprises: (1-1) a light source unit which has a light emitting element and a first collimator lens and which emits a parallel plane wave light beam. It is characterized in that they are arranged so as to face each other and are detachably connected to a second collimator lens that converts the light flux of the parallel plane wave into a light flux that converges or diverges.

[0016] In particular, (1-1-1) the light source unit has a second lens holder for holding the second collimator lens and fixing it at a predetermined position, and a connecting means for connecting the second lens holder by an in-row structure. Upon coupling the light source unit and the second lens holder, a case covering the light source unit is pressed against the rear part of the light source unit. (1-1-2) The light source unit holds the second collimator lens. And a second lens holder that is fixed at a predetermined position and has a coupling means that couples with a taper structure, and the second lens holder includes a temporary fixing member for the light source unit, and the light source unit and the second lens holder. When connecting with the lens holder of
The case that covers the light source unit is in pressure contact with the rear portion of the light source unit.

Further, in the configuration of the displacement measuring apparatus of the present invention, (1-2) a light source unit having a light emitting element and a first collimator lens for emitting a light flux of a parallel plane wave is arranged opposite to the light source unit. Displacement information of the displacement object is detected using a light beam from a light source module detachably connected to a second collimator lens that converts the light beam of the parallel plane wave into a light beam that converges or diverges. It has a feature.

(1-2-1) In particular, (1-2-1) the light source unit has a second lens holder for holding the second collimator lens and fixing the second collimator lens at a predetermined position of the displacement measuring device. And a case that covers the light source unit press-contacts with a rear portion of the light source unit when the light source unit and the second lens holder are coupled to each other. Second lens holder for holding the collimator lens and fixing it at a predetermined position of the displacement measuring device, has a coupling means for coupling with a taper structure, and the second lens holder has a temporary fixing member for the light source unit. When the light source unit and the second lens holder are coupled, a case covering the light source unit is in pressure contact with the rear portion of the light source unit.

[0019]

1 is an explanatory view of an optical system of a first embodiment in which the light source module of the present invention is applied to a rotary encoder as a displacement measuring device, and FIG. 2 is a main part of the first embodiment of the light source module of the present invention. It is a schematic diagram and a figure explaining the exchange method.

FIG. 1A is a plan view of the optical system.
(B) is a side view thereof. In the figure, 4 is a semiconductor laser (light emitting element), 3 is a first collimator lens, which converts laser light emitted from the semiconductor laser 4 into parallel plane waves. The semiconductor laser 4 and the first collimator lens 3 each constitute an element of the light source unit 1.

Reference numeral 2 denotes a second collimator lens, which converts a parallel plane wave emitted from the light source unit 1 into convergent light which is once condensed on the reflecting surface 7 of the reflecting means 6, as shown in FIG. 1 (C) described later. To do. The light source unit 1 and the second collimator lens 2 form one element of the light source module.

Reference numeral 21 is a polarization beam splitter having a polarization plane 22 built therein, 25 is a prism, 26 is a quarter wavelength plate, 6 is a reflecting member, 28 is a quarter wavelength plate, 29 is a light splitting element, 30,
Reference numeral 31 is a polarizing plate, and 8 is a light receiving sensor. Reference numeral 5 is a radiation diffraction grating (optical grating) formed on a transparent disk (scale) 40 fixed to the object to be measured. In addition,
When two identical members are used, they are distinguished by adding a and b.

In the embodiment, the collimator lens system is composed of two lenses, that is, the first collimator lens 3 and the second collimator lens 2, and the light beam is set as a parallel plane wave between the two lenses, and one of the first and second collimator lenses is used. The second collimator lens 2 is permanently fixed in the encoder body, and the other semiconductor laser 4 and the first collimator lens 3 are connected to the light source unit 1.
As a unit, the encoder body is replaceable. As a result, the predetermined convergence and divergence of the light flux can be maintained before and after the replacement of the light source, and the light source can be quickly replaced without removing the entire cover.

The operation of the optical system will be described. Example 1
In the above, the light beam emitted from the semiconductor laser 4 is changed into a light beam which converges to a predetermined position by the first and second collimator lenses 3 and 2, and after entering the polarization beam splitter 21, a reflected light beam 23 having a substantially equal light amount on the polarization plane 22. And transmitted light flux 2
It is divided into two linearly polarized light beams of No. 4.

Among them, the reflected light beam 23 is reflected by the prism 25a and is incident on the position M1 on the radial diffraction grating 5 formed on the transparent disk 40 fixed to the rotating object as the object to be measured. The diffracted light of a specific order among the various diffracted light generated by the transmission diffraction by the radiation diffraction grating 5 is emitted from the radiation diffraction grating 5 in a substantially vertical direction, and the 1/4 wavelength plate 26
It becomes circularly polarized light by a and is reflected by the reflection member 6a,
The light beam travels back through the same optical path again and again passes through the 1/4 wavelength plate 26a to become linearly polarized light having a 90 ° polarization direction different from that at the time of incidence, and reenters the radiation diffraction grating 5 at substantially the same position M1. Of the various diffracted light generated by being re-diffracted by the radiation diffraction grating 5, the diffracted light of a specific order is the prism 25a.
It re-enters the polarization beam splitter 21 via the.

The transmitted light beam 24 has an optical path symmetrical to the reflected light beam 23 with respect to the polarization plane 22, and is located on the radiation diffraction grating 5 at a position M1 and a position M2 which is substantially point-symmetrical with respect to the center of rotation.
At the radiation diffraction grating 5 and undergoes transmission diffraction, the specific diffracted light is reflected by the reflecting member 6b, again enters the radiation diffraction grating 5, undergoes transmission diffraction again, and diffracted light of a specific order is transmitted to the prism 25b. It is incident, reflected, and re-enters the polarization beam splitter 21.

These two light fluxes are combined via a polarization plane 22 to form a light flux 27, which after passing through a quarter-wave plate 28, is split into two light fluxes by a light splitting element 29, and the respective light fluxes are polarized with respect to each other. Polarizing plates 30 and 31 arranged in different directions by 45 °
Both light fluxes are made incident on the respective light receiving sensors 8a and 8b as linearly polarized light having a phase difference of 90 °.

In such a structure, the radiation diffraction grating 5
When the diffraction order on the side of the reflected light beam 23 is m and the diffraction order on the side of the transmitted light beam 24 is n, (2m-2n) sine waveforms are obtained from the light receiving sensor 8 by the rotational displacement of 1 pitch. . For example, when m = 1 and n = -1,
Four sine waveforms are obtained by the rotational displacement of the radiation diffraction grating 5 for one pitch, and the rotation amount can be detected with high resolution. Next, the structure of the light source module of the first embodiment and the method of replacing the light source unit 1 will be described. FIG. 2A shows the first embodiment.
2 is a schematic view of a main part of FIG. 2, and is an explanatory view of a process of mounting the light source unit 1 of Example 1 on an encoder.
FIG. 6B is a diagram when the light source unit 1 of the first embodiment is mounted on the encoder.

In the figure, 10 is a first lens holder for holding the first collimator lens 3, the outer cylindrical surface of which has a male-side inlay portion (coupling means). 11
Is a laser holder, which is made of an electrically insulating material and has a semiconductor laser 4 and a substrate 12 with a protective circuit built therein. 1
Reference numeral 4 is a circuit pattern, which connects the substrate 12 with the protection circuit and the terminal 13 on the encoder side. Reference numeral 13 is a terminal on the main board 32 side of the encoder body.

The semiconductor laser 4, the first collimator lens 3, the lens holder 10, and the laser holder 1
1, the substrate 12 with the protection circuit, the circuit pattern 14 and the like respectively constitute one element of the light source unit 1.

In the light source unit 1, the mutual distance and position between the first collimating lens 3 and the light emitting point position of the semiconductor laser 4 are adjusted in advance within a predetermined accuracy, and the light source unit 1 emits a parallel plane wave light beam. Inject.

Reference numeral 15 is a second lens holder,
It holds the collimator lens 2 and has a female-side inlay portion on the light beam incident side. The second lens holder 15 is fixed to the encoder side.

Light source unit 1 and second lens holder 1
5 is connected by an inlay structure. In this case, even if a slight optical axis shift occurs between the collimator lenses 2 and 3 within a predetermined tolerance due to the inlay structure, a light flux of parallel plane waves is incident on the second collimator lens 2 from the light source unit 1. Therefore, it is possible to maintain the predetermined convergence and divergence relationship of the light flux before and after the replacement of the trailing light source.

Reference numeral 16 denotes a case which also has a function of finally fixing the light source unit 1 by pushing the light source unit 1 from the rear part after the light source unit 1 is inlay-bonded to the second lens holder 15.

Therefore, when replacing the light source unit 1 in the present embodiment, the case 16 is removed, the light source unit is removed, a new light source unit 1 is inserted and inlay connection is performed, and finally the case 16 is screwed in, and the case shown in FIG. The replacement of the light source unit 1 is completed in the state shown in B).

The light source unit 1, the second collimator lens 2, the second lens holder 15, the terminal 13 and the case 16 each constitute one element of the light source module of the present invention.

FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the light source module of the present invention. In the second embodiment, common symbols are used for the same parts as in the first embodiment. The second embodiment differs from the first embodiment in that the light source unit 1 and the second lens holder 15 are coupled to each other in the taper coupling in the second embodiment. That is, in the second embodiment, the lens holder 10
The second lens holder 15 and the second lens holder 15 have tapered portions 17 (coupling means). Further, a groove 18 is provided on the outer circumference of the laser holder 11, and a plurality of leaf springs (temporary fixing members for the light source unit) 19a and 19b corresponding to the groove 18 are provided in the second portion.
It is provided on the lens holder 15.

The second embodiment can not only reduce the optical axis decentering between the first and second collimator lenses 3 and 2 as compared with the coupling method by the inlay structure of the first embodiment, but also
The light source unit 1 can be inserted and attached more easily, and at the same time, the light source unit 1 can be temporarily fixed by the leaf spring 19 regardless of the direction of the mounting posture of the encoder body, which facilitates replacement work in particular. The leaf spring 19
Also constitutes an element of the light source module of the present invention.

Although the present invention is applied to the rotary encoder in the above embodiments, the present invention can be widely applied to other information devices such as a linear encoder or a light emitting element as a light source.

[0040]

According to the present invention, with the above structure, when a failure due to a light source occurs in a device such as an encoder,
A light source module and a displacement measuring device using the light source module, which allows quick and simple light source replacement from the outside without removing an encoder or the like from the control system system, have been achieved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an optical system of Example 1 in which a light source module of the present invention is applied to a rotary encoder.

FIG. 2 is a schematic view of the essential parts of Embodiment 1 of the light source module of the present invention.

FIG. 3 is a schematic view of a main part of a second embodiment of the light source module of the present invention.

FIG. 4 is a schematic view of a main part of a conventional rotary encoder (A) Optical system plan view (B) Optical system side view (C) Main body sectional view

FIG. 5: Light flux change diagram due to change in collimation interval

[Explanation of symbols]

 1 Light Source Unit 2 Second Collimator Lens 3 First Collimator Lens 4 Semiconductor Laser 10 First Lens Holder 11 Laser Holder 12 Protective Circuit Board 13 Terminal 14 Circuit Pattern 15 Second Lens Holder 16 Case 19 Leaf Spring

Claims (6)

[Claims] 1. A light source unit, which has a light emitting element and a first collimator lens and emits a parallel plane wave light beam, is arranged to face the light source unit, and converts the parallel plane wave light beam into a light beam that converges or diverges. The light source module is detachably connected to the second collimator lens. 2. The light source unit has a second lens holder that holds the second collimator lens and fixes it at a predetermined position, and has a coupling means that couples the second lens holder with an in-row structure. 2. The light source module according to claim 1, wherein a case that covers the light source unit is pressed against a rear portion of the light source unit when the light source unit is coupled to the lens holder. 3. The light source unit has a second lens holder that holds the second collimator lens and fixes it at a predetermined position, and has a coupling means that couples with a taper structure. 2. A temporary fixing member for a light source unit is provided, and a case covering the light source unit is pressed against a rear portion of the light source unit when the light source unit and the second lens holder are coupled. Light source module. 4. A light source unit, which has a light emitting element and a first collimator lens and emits a light flux of a parallel plane wave, is arranged to face the light source unit and converts the light flux of the parallel plane wave into a light flux that converges or diverges. The displacement measuring device is characterized in that the displacement information of the displacement object is detected by using the light flux from the light source module detachably connected to the second collimator lens. 5. The light source unit has a second lens holder that holds the second collimator lens and fixes the second collimator lens at a predetermined position of the displacement measuring device, and has a joining means that joins the second lens holder with an in-row structure. 5. The displacement measuring device according to claim 4, wherein a case that covers the light source unit is brought into pressure contact with a rear portion of the light source unit when the light source unit is coupled with the second lens holder. 6. The light source unit has a second lens holder that holds the second collimator lens and fixes the second collimator lens at a predetermined position of the displacement measuring device, and has a coupling means that couples in a taper structure. The lens holder includes a temporary fixing member for the light source unit, the light source unit and the second light source unit.
The displacement measuring device according to claim 4, wherein a case that covers the light source unit is pressed against a rear portion of the light source unit when the lens holder is connected to the lens holder.