JPH07174550A - Optical displacement sensor - Google Patents

Abstract

PURPOSE:To make an apparatus compact and light-weight, by eliminating adjustment required for mutually positioning parts, e.g. registering optical axes of parts. CONSTITUTION:A hologram collimator lens 2 and a hologram condenser lens 3 are formed on the upper surface of a transparent flat plate 5, while a semiconductor laser 1 and a PSD 4 are set on the bottom surface of the plate. Positional relationships between the semiconductor laser 1 and hologram collimator lens 2, between the hologram collimator lens 2 and hologram condenser lens 3 and between the hologram condenser lens 3 and PSD 4 are definitely fixed, thus making it unnecessary to adjust each position of the parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical displacement sensor for detecting the position of an object to be detected by applying the principle of triangulation.

[0002]

2. Description of the Related Art As a displacement sensor for optically detecting a distance to an object to be detected or a displacement of the object to be detected, there has been a conventional sensor shown in FIG.
Some have the configuration shown in. In FIG. 4, light from a light emitting element 101 such as a semiconductor laser is distributed to an object to be detected 110 via a light projecting lens 102, and reflected light from the object to be detected 110 is passed through a light receiving lens 103 to a light position detecting element (hereinafter The light is received at 104). Object 1
The change in the distance of 10 to the light receiving lens 103 appears as a change in the incident angle of the reflected light on the object to be detected 110 with respect to the light receiving lens 103, and is reflected by the PSD 104 located on the opposite side of the object to be detected 110 with the light receiving lens 103 interposed therebetween. The position where the light spot is formed changes depending on the incident angle change of the reflected light, that is, the position change of the detected object. For example, in FIG. 4, when the detected object 110 changes from position a → b → c, the formation position of the reflected light spot on the PSD 104 changes from a ′ → b ′ → c ′. The PSD 104 outputs a current at both ends having a magnitude corresponding to the light receiving position in the longitudinal direction. Therefore, PSD10
The position of the object 110 to be detected can be detected by changing the incident angle of the reflected light by measuring the current across both ends of No. 4.

[0003]

However, the conventional displacement sensor includes the semiconductor laser 101 and the projection lens 10.
2. The condenser lens 103 and the PSD 104 need to be arranged in the optical path passing through the detection surface of the object to be detected, and
Since the combination lens is used as both the light projecting lens 102 and the condensing lens 103, it is necessary to arrange a larger number of components at appropriate positions, which makes adjustment work such as optical axis alignment of individual components difficult. In addition to the above problem, there is also a problem that the request for downsizing and weight saving of the sensor cannot be satisfied. Further, when the distances of a plurality of points of the object to be detected from the reference plane are simultaneously measured, it is difficult to accurately arrange the plurality of displacement sensors on the same plane.

An object of the present invention is to facilitate the arrangement of the light emitting element, the light projecting lens, the light receiving lens, and the PSD, and to reduce the number of parts by reducing the number of adjustment points such as optical axis alignment. It is an object of the present invention to provide a displacement sensor that can realize a small size and a light weight, and can easily and accurately arrange a plurality of displacement sensors even when the distances of a plurality of points from a reference plane are simultaneously measured.

[0005]

An optical displacement sensor according to the present invention includes a single or a plurality of light emitting elements, a light projecting lens for distributing light emitted from the light emitting elements to an object to be detected, and reflection on the object to be detected. The same number of transparent flat plates that form the same number of light receiving lenses as the light emitting elements on the same surface as the light emitting elements, and the same number of the light emitting elements that output the detection signal according to the position of the reflected light spot condensed through the light receiving lenses. And a signal processing circuit for processing a detection signal of the optical position detecting element.

Further, the light emitting element and the optical position detecting element are fixed at predetermined positions on the transparent flat plate.

Further, a marker is provided on the same surface of the transparent flat plate on which the light projecting lens and the light receiving lens are formed, the marker indicating the mounting position of the light emitting element and the light position detecting element in the planar direction. Is.

[0008]

In the present invention, the same number of light emitting lenses and light receiving lenses are formed on the same surface of the transparent flat plate. Therefore, the positional relationship between the light projecting lens and the light receiving lens and the direction of the optical axis of each lens are uniquely determined,
There is no need to adjust these.

Further, in the invention described in claim 2, since the light projecting element and the light position detecting element are fixed to the transparent flat plate on which the light projecting lens and the light receiving lens are formed, the light projecting lens as described above is provided. Not only the positional relationship between the light emitting element and the light receiving lens, but also the positional relationship between the light emitting element and the light position detecting element is uniquely determined. Therefore, all the components constituting the displacement sensor can be arranged at proper positions simply by arranging the transparent flat plate at proper positions.

Further, in the third aspect of the invention, the marker indicating the proper mounting position in the plane direction of the light emitting element and the optical position detecting element with respect to the light projecting lens and the light receiving lens formed on the transparent flat plate is provided. And formed at the same time as the light receiving lens. Therefore, when the light emitting element and the optical position detecting element are attached, the accurate positions in the plane direction of the light emitting element and the optical position detecting element can be easily recognized according to the marker formed on the transparent flat plate.

[0011]

1 is a side view and a plan view showing the structure of an optical displacement sensor according to an embodiment of the present invention. A hologram collimator lens 2 and a hologram condenser lens 3 are formed on the upper surface of the transparent flat plate 5. Further, the semiconductor laser 1 and the PSD 4 are attached to the lower surface of the transparent flat plate 5. The semiconductor laser 1 is driven by a drive circuit (not shown) and emits divergent light upward. The light emitted from the semiconductor laser 1 enters the transparent flat plate 5, is converted into parallel light by the hologram collimator lens 2, and is distributed to the object to be detected 10. Part of the light reflected by the detected object 10 is
The hologram condensing lens 3 converts the light into focused light, which is incident on the transparent flat plate 5 to form a reflected light spot on the light receiving surface of the PSD 4. The PSD 4 outputs a current at both ends according to the focus position of the reflected light spot on the light receiving surface.

In the above structure, the object 10 to be detected is shown in FIG.
When the position a → b → c shown in FIG.
The incident angle of the reflected light on the light receiving lens 3 at 0 changes, and the formation position of the reflected light spot on the light receiving surface of the PSD 4 also changes as a ′ → b ′ → c ′. Along with this, the value of the current across the PSD 4 changes. Therefore,
The distance to the detected object 10 can be measured by measuring the current across the PSD 4 in a signal processing circuit (not shown).

FIG. 2 is a plan view of an optical displacement sensor according to another embodiment of the present invention. As shown in the figure, three hologram collimating lenses 2 and three hologram condensing lenses 3 are formed on the upper surface of the transparent plate 15, and three semiconductor lasers 1 and PSDs are provided on the lower surface.
4 is attached.

By using the displacement sensor configured as described above, it is possible to simultaneously measure the distances to three points on the object to be detected with the upper surface of the transparent flat plate 15 as a reference surface. Therefore, the present invention can be applied to an autocollimator in which an object to be detected is horizontally arranged so that the measurement distances of a single object to be detected are equal. Further, by performing the same measurement on a plurality of detected objects, the plurality of detected objects can be arranged so as to be parallel to each other. Further, the present invention can be applied to a surface step gauge that measures the surface shape of the object to be detected.

The numbers of the hologram collimator lens 2, the hologram condenser lens 3, the semiconductor laser 1 and the PSD 4 formed and attached to the transparent flat plate 15 are not limited to three.

FIG. 3 is a diagram showing a method for producing the above optical displacement sensor. First, the resist material 31 is applied over the entire surface of the transparent flat plate 5 made of glass (BK7 or the like) or resin (PMMA or the like) (FIG. 3A), and the exposure mask 32 is placed on the upper surface. Exposure light is irradiated (FIG. 2B). In this way, as shown in FIG. 3C, the transparent flat plate 5 on which the resist film 33 is formed is subjected to reactive ion etching, so that the hologram collimator lens 2 and the hologram condenser lens are formed on the upper surface of the transparent flat plate 5. 3 is formed ((D) in the same figure). The semiconductor laser 1 and the PSD 4 are aligned and attached to the lower surface of the transparent flat plate 5 ((E) in the figure). Prior to this alignment, an ultraviolet curable resin is applied in advance, and after alignment, the semiconductor laser 1 and the PSD 4 are adhesively fixed to the lower surface of the transparent flat plate 5 by irradiating ultraviolet rays.

In the exposure mask 32, the lens patterns of the hologram collimator lens 2 and the hologram condenser lens 3 are accurately positioned and formed, and
The marker 35 that serves as a reference for the mounting position of the PSD 4 is formed at an accurate position with respect to the two types of hologram lens patterns. As a result, the marker 6 is formed on the upper surface of the transparent flat plate 5 that has been subjected to the reactive ion etching, together with the hologram collimator lens 2 and the hologram condenser lens 3 at appropriate positions with respect to the hologram condenser lens 3. PS
When the D4 is attached to the lower surface of the transparent flat plate 5, the position where the PSD 4 should be attached can be visually confirmed by the marker 6, and the PSD 4 can be easily fixed at the correct position.

Since the semiconductor laser 1 is located vertically below the hologram collimator lens 2 in this embodiment, when mounting the semiconductor laser 1, the mounting position should be determined by using a part of the hologram collimator lens 2 as a marker. You can In this case, the hologram collimator lens 2 serves as a marker indicating the mounting position of the semiconductor laser 1, but if the proper mounting position of the semiconductor laser 1 is not vertically below the hologram collimating lens 2,
A marker similar to the marker 6 can be created by reactive ion etching.

Since the hologram lens formed on the upper surface of the transparent flat plate 5 as described above has a function of converting incident light rays into arbitrary light rays, a combination lens is used as in the conventional example shown in FIG. It is not necessary to collect light that is incident with a large inclination with respect to the optical axis of the lens, so that the semiconductor laser 1 is formed on the same surface of the transparent flat plate 5.
And PSD4 can be arranged, and miniaturization of the device can be realized. When detecting a change in the incident angle of the reflected light from the detection object 10 as a change in the reflected light spot on the light receiving surface of the PSD 4, the mounting position of the PSD 4 in the displacement direction of the reflected light spot is accurately determined. Although it is necessary to form a marker on the transparent flat plate 5 at the same time when the lens is formed on the transparent flat plate 5, a marker indicating the mounting position of the PSD 4 is formed.
The SD4 can be positioned accurately and easily.

[0020]

According to the present invention, the light projecting lens and the light receiving lens can be formed at the correct positions on the same surface of the transparent flat plate, and the relative positional relationship between the light projecting lens and the light receiving lens is adjusted. There is an advantage that it is not necessary and the device can be downsized.

By mounting the light emitting element and the optical position detecting element at predetermined positions on the transparent plate, the relative positional relationship between the light emitting element and the optical position detecting element with respect to the light projecting lens and the light receiving lens is uniquely fixed. Therefore, there is no need to adjust the positional relationship between them, and the assembly work of the displacement sensor can be extremely facilitated.

Further, by forming a marker indicating the mounting position of the light emitting element and the optical position detecting element on the upper surface of the transparent flat plate, the light emitting element and the optical position detecting element can be accurately and easily attached at appropriate positions.

[Brief description of drawings]

FIG. 1 is a side view and a plan view of an optical displacement sensor that is an embodiment of the present invention.

FIG. 2 is a plan view of an optical displacement sensor according to another embodiment of the present invention.

FIG. 3 is a diagram showing a method for producing an optical displacement sensor that is an embodiment of the present invention.

FIG. 4 is a side view showing a configuration of a conventional optical displacement sensor.

[Explanation of symbols]

 1-semiconductor laser (light-emitting element) 2-hologram collimating lens (projecting lens) 3-hologram condensing lens (light-receiving lens) 4-PSD 5-transparent flat plate 6-marker 10-detection object

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehisa Ishihara 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Prefecture

Claims (3)

[Claims] 1. A single or a plurality of light emitting elements, a light projecting lens that distributes light emitted from the light emitting elements to an object to be detected, and a light receiving lens that collects reflected light from the object to be detected, in the same number as the light emitting elements. Each of the transparent flat plates formed on the same surface, the same number of light position detecting elements as the light emitting elements that output a detection signal according to the position of the reflected light spot condensed through the light receiving lens, and the detection of the light position detecting elements An optical displacement sensor, comprising: a signal processing circuit that processes a signal. 2. The optical displacement sensor according to claim 1, wherein the light emitting element and the optical position detecting element are fixed at predetermined positions on the transparent flat plate. 3. A marker for indicating the mounting position of the light emitting element and the optical position detecting element in the plane direction is provided on the same surface of the transparent flat plate on which the light projecting lens and the light receiving lens are formed. The optical displacement sensor according to.