JP2531890Y2 - Optical sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical sensor including an optical element and a light receiving element.

[Conventional technology]

Conventionally, such an optical sensor is configured, for example, as shown in FIG. That is, in FIG. 2, the optical sensor 1 includes a split mirror 2 having a plurality of, in the illustrated case, three concave mirror portions 2a, 2b, 2c, the optical portion, The light emitted from the light emitting element 3 is transmitted to each of the concave mirror portions 2a, 2 of the split mirror 2.
b, 2c, each concave mirror part 2a, 2b, 2c
Are converted into substantially parallel light beams by the optical action of the above, and irradiate three detection areas 4a, 4b, 4c arranged in the longitudinal direction, respectively. Then, each of these detection areas 4a, 4b, 4c
When an object or the like existing inside moves, the detection area
Fluctuations in the amounts of light from 4a, 4b, and 4c are detected by a light-receiving element (not shown) disposed at substantially the same position as the light-emitting element 3, and the output signals of the light-receiving elements are appropriately processed, whereby each The presence or movement of the object or the like in the detection areas 4a, 4b, 4c is detected.

[Problems to be solved by the invention]

By the way, in the optical sensor having such a configuration,
Each concave mirror portion 2a, 2b, 2c of the split mirror 2 needs to be formed so as to have an optical axis tilted corresponding to the detection area 4a, 4b, 4c, a different radius of curvature and a large aperture ratio. As a result, the manufacturing process becomes complicated and the cost increases, and it is difficult to increase the processing accuracy. Therefore, the aberration correction cannot be performed sufficiently, and the detection accuracy decreases. was there.

Therefore, an optical sensor as shown in FIG. 3 is also known.

That is, in FIG. 3, the optical sensor 1 'includes a plate-shaped prism 5 having a prism surface portion 5a, a flat surface portion 5b, and a prism surface portion 5c formed on one surface in the longitudinal direction. , One parabolic reflecting mirror 6 disposed behind the prism 5 and the reflecting mirror 6
And a light-emitting element 7 disposed on the optical axis so as to face the reflection mirror 6. Light emitted from the light-emitting element 7 is reflected by the reflection mirror 6 and is substantially parallel to the light-emitting element 7. After being turned into a light beam,
By passing through the prism surface portions 5a, 5b, and 5c, respectively, the optical axis is deflected on the prism surface portions 5a, 5c based on the action of the prism. The three detection areas 4a, 4b, 4c arranged in the direction are irradiated.

In the optical sensor 1 ′ having such a configuration, since a parabolic mirror is used as the reflection mirror 6, light from the light emitting element 7 is applied to the prism surfaces 5 a and 5 c of the prism 5.
After passing through, almost all light is detected in each detection area 4a, 4b, 4c.
Therefore, a relatively high light-collecting efficiency can be obtained, and the focal point of the reflection mirror 6 can be brought close to the prism 5, so that the whole can be made compact.

However, this parabolic mirror has problems that it is difficult to design, process, and polish it, it is difficult to obtain a desired accuracy, and the manufacturing cost including the production of a mold increases.

An optical sensor 1 ″ as shown in FIG. 4 is also known.

That is, in FIG. 4, the optical sensor 1 ″ has its light-emitting portion formed as a prism surface 8a, a plane portion 8b, and a prism surface 8c having an angle different from that of the prism surface 8a in the front surface in the longitudinal direction. And a light emitting element 9 disposed on the optical axis of the Fresnel lens portion 8d behind the optical member 8 and having a rear surface formed as a Fresnel lens portion 8d. ing.

In this case, the light from the light emitting element 9 becomes parallel light that has passed through the Fresnel lens portion 8d of the optical member 8, and then passes through the prism surface portion 8a, the plane portion 8b, and the prism surface 8c, respectively. , 8c, the optical axis is deflected based on the action of the prism, and the plane portion 8b is transmitted as it is, and three detection regions 4 are arranged in the longitudinal direction.
a, 4b, 4c are illuminated, and the detection areas 4a, 4
b, 4c, the movement of an object or the like moves to detect a change in the amount of light from the detection areas 4a, 4b, 4c by a light-receiving element (not shown), and appropriately process an output signal of the light-receiving element. Accordingly, the presence or movement of the object or the like in each of the detection areas 4a, 4b, and 4c is detected.

According to the optical sensor 1 ″ configured as described above, since almost parallel light beams are formed by the Fresnel lens portion 8d of the prism 8, almost all light beams after passing through the prism surface portions 8a and 8c of the prism 8 are formed. Light will be focused on each detection area 4a, 4b, 4c, and relatively high focusing efficiency can be obtained,
The Fresnel lens part 8d itself needs to have a considerably fine pitch and a large Fresnel angle, and there is a problem that its manufacture is difficult and the cost is increased.

Further, in any of the optical sensors described above, the split mirror 2, the reflection mirror 6, or the Fresnel lens unit 8d is
In order to increase the detection accuracy, it is necessary to increase the size,
There is a limit to the size increase, and in any case, the aperture ratio of the optical sensor as a whole is about 0.3 to 0.4, and the residual aberration becomes considerably large, so that the detection accuracy can be made very high. Did not.

In view of the above, this invention can be manufactured relatively easily and inexpensively, and by increasing the aperture ratio, improves the light collection efficiency to the detection area and increases the detection accuracy. It is intended to provide an optical sensor.

[Means for solving the problem]

According to the invention, the light emitted from the light emitting element is reflected by the mirror to irradiate the detection areas, and the light amount fluctuation from each detection area is detected at the same position as the light emitting element. In the optical sensor to detect by
A prism including a plurality of prism portions having substantially different prism angles formed sequentially along the longitudinal direction and a flat portion formed in parallel with the prism portions,
Two concave mirrors are provided integrally behind the prism so as to be generally concave toward the prism, and have focal points at substantially the same position with respect to each detection area to be detected. Reflecting mirror, and a light-emitting element and a light-receiving element disposed in the vicinity of the focal point between the prism and the reflecting mirror. This is achieved by an optical sensor, wherein the concave mirror portion constitutes one detection area via a corresponding prism portion.

[Action]

According to this invention, as for the detection area corresponding to each concave mirror portion of the reflection mirror, the light flux for each detection area passes through the flat portion of the plasma, and is reflected and condensed by each concave mirror portion of the reflection mirror. Through the light emitting element or the light receiving element arranged near the focal position.

On the other hand, with respect to the detection area located at the center, the light flux from the front with respect to this detection area is bent by transmitting through each prism part of the prism, and is directed in the optical axis direction with respect to each concave mirror part of the reflecting mirror. And is reflected and condensed by the concave mirror portion, and passes through a light receiving element or a light receiving element disposed near the focal position.

Therefore, it is not necessary to separately prepare a concave mirror for the light flux from the front, and therefore the entire reflecting mirror can be configured to be relatively small. Conversely, in the case of a reflecting mirror of the same size, the reflecting mirror for each detection area is not required. Since the area of each concave mirror can be increased, the aperture ratio of the entire optical sensor becomes large. Further, since the incidence and reflection on each concave mirror are performed near the optical axis of the concave mirror, residual aberration is relatively reduced. Can be smaller.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

FIG. 1 shows an embodiment of the optical sensor according to the present invention.

The optical sensor 10 has a light-emitting portion, the front surface of which is a flat surface and the rear surface of the prism surface portion 11a, and a prism surface portion 11b having a substantially different prism angle from the prism surface portion 11a in the longitudinal direction. And parallel to these prism surface portions 11a and 11b, and the flat portion 1 on the other side.
A plate-like prism 11 formed as 1c (see FIG. 1 (D)), and the prism 11
A reflecting mirror 12 integrally disposed so as to become concave as a whole toward 11; a prism 11 and a reflecting mirror 12;
And a light-emitting element 13 disposed so as to face the spherical reflection mirror 12 between the light-emitting element 13 and the light-emitting element 13.

The reflection mirror 12 is vertically divided into two concave mirror portions 12a and 12b in the drawing, and these concave mirror portions 12a and 12b
Are detection areas 14a, 14b, 14c to be detected, respectively, which will be described later.
The light fluxes for the detection areas 14c and 14a are focused on the same focal position, that is, the light emitting element 13.

The optical sensor 10 according to the present invention is configured as described above, and the optical axis of light emitted from the light emitting element 13 is reflected by the concave mirror portions 12a and 12b of the reflection mirror 12, respectively, and then the flat portion 11c of the prism 11 is reflected. The transmitted light flux (see FIG. 1A) passes through the flat portion 11c as it is, and moves downward or upward in the case of the drawing, and
Light fluxes associated with c and 14a and transmitted through the prism surfaces 11a and 11b of the prism 11 (see FIG. 1 (B))
Is deflected by the action of the prism surface portions 11a and 11b, and becomes parallel light that exits from the surface of the prism 11 in the vertical direction, and is related to the detection area 14b.

In this case, since the light reaching each of the detection areas 14a, 14b, and 14c is incident at a relatively small angle with respect to the optical axis of each of the concave mirror portions 12a and 12b of the reflection mirror 12, the aperture ratio needs to be made too large. And the residual aberration is relatively small.

In this way, light from the light emitting element 13 is transmitted to each detection area.
Since the light is efficiently collected on the light receiving elements 14a, 14b, and 14c, the detection accuracy of the presence or movement of the object in the detection areas 14a, 14b, and 14c by the light receiving element (not shown) can be improved.

In the above description, the case where the optical elements are all light-emitting elements has been described. However, the present invention is not limited to this, and it is apparent that the present invention can be applied to the case where the optical elements are light-receiving elements. The effect is exactly the same, except that the traveling directions of light and light are reversed.

[Effect of the invention]

As described above, according to the present invention, with respect to the detection regions corresponding to the respective concave mirror portions of the reflection mirror, the luminous flux for each of the detection regions passes through the flat portion of the prism, so that each of the concave mirror portions of the reflection mirror. After being reflected and condensed, the light passes through a light-emitting element or a light-receiving element disposed near the focal point. On the other hand, for a detection area located in the center, a light beam from the front with respect to the detection area passes through each prism portion of the prism. The light is deflected by being transmitted, and is incident on each concave mirror portion of the reflecting mirror in the optical axis direction. The light is reflected and condensed by the concave mirror portion, and is emitted near the focal position. It passes through the element or the light receiving element.

Therefore, there is no need to separately prepare a concave mirror for the light beam from the front, and the entire reflecting mirror can be configured to be relatively small. Conversely, in the case of a reflection mirror of the same size, since the area of each concave mirror portion with respect to each detection area can be increased, the aperture ratio of the entire optical sensor increases, and the incidence and reflection on each concave mirror portion are reduced. Since it is performed in the vicinity of the optical axis of the concave mirror portion, the residual aberration is relatively small, and thus the light collection efficiency for the detection area where the presence or movement of the object is to be detected or the light collection efficiency from the detection area is reduced. This improves the detection accuracy.

Thus, according to the present invention, an extremely excellent optical sensor that can be manufactured relatively easily and at low cost, and by increasing the aperture ratio, the light collection efficiency on the detection area is improved and the detection accuracy is improved. Will be provided.

[Brief description of the drawings]

FIG. 1A is a schematic sectional view showing a light beam transmitted through a plane portion of a prism in an embodiment of the optical sensor according to the present invention, FIG. 1B is a schematic sectional view showing a light beam transmitted through a prism surface portion of the prism, (C) is a schematic plan view, and (D) is a front view of the prism. 2 to 4 are schematic cross-sectional views each showing a configuration example of a conventional optical sensor. 10 optical sensor; 11 prism; 11a, 11b prism surface; 11c flat surface; 12 reflecting mirror; 12a, 12b
Concave mirror section; 13 light-emitting element; 14a, 14b, 14c detection area.

Claims (1)

(57) [Scope of request for utility model registration] An optical sensor for irradiating a detection area with light emitted from a light emitting element being reflected by a mirror and detecting a change in the amount of light from each detection area by a light receiving element arranged at substantially the same position as the light emitting element. A prism comprising a plurality of prism portions formed sequentially along a longitudinal direction and having substantially different prism angles from each other, and a flat portion formed in parallel with the prism portions, A reflecting mirror provided with two concave mirrors which are integrally disposed so as to be concave as a whole toward the prism, and which have focal points at substantially the same position with respect to each detection area to be detected. A light-emitting element and a light-receiving element disposed in the vicinity of the focal point between the prism and the reflection mirror, and wherein the two concave mirror portions of the reflection mirror are the flat surface portions. An optical sensor, wherein each of the detection areas constitutes a detection area via the corresponding prism, and the concave mirror section constitutes one detection area via the corresponding prism section.