JPH07286811A - Optical device - Google Patents

Abstract

PURPOSE:To expand the distance measuring range of an optical device by constituting the optical device so that the dividing line of a photoreceptor element can become parallel to the position changing direction of the spot of reflected light on a light receiving surface generated when the distance from a light emitting section or light receiving section to an object varies. CONSTITUTION:A light emitting section is composed of a light emitting element 1 which emits a luminous flux toward objects (M4, M5, and M6) and a light projecting lens 3 and a light receiving section is composed of a light receiving element 2 and light receiving lens 4 which receive reflected light from the objects in the form of a spot. The light emitting element 1 is composed of a photodiode, etc., and the light receiving element 2 is constituted so that the dividing line in its area can become parallel to the position changing direction of the received spot of the reflected light when the distances from element 2 to the objects change. Therefore, the extent in which the spot intersects the dividing line becomes larger and the moving extent of the spot is expanded, and then, the distance measuring range is expanded, because the spot moves in parallel with the dividing line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention emits light to an object,
The present invention relates to an optical device that measures the distance to an object by receiving the reflected light.

[0002]

2. Description of the Related Art A conventional optical distance measuring device is shown in FIG.
There is a photoelectric sensor using a trigonometric distance measuring system having a configuration as shown in FIG. The optical system of this device is composed of a light emitting element 1 for projecting light, a light projecting lens 3, and a light receiving element 2 for receiving light and a light receiving lens 4, and the light receiving element 2 has a one-dimensional direction (position detection direction). For example, a two-divided photodiode (PD), a position detection element (PSD), or the like that can detect the spot light receiving position is used. When the distance from the device to the objects (M1, M2, M3) changes, as shown in FIG.
On the light receiving surface of the, the spot (S1,
S2, S3) moves to a position corresponding to the distance of the object in a fixed direction. The light receiving element 2 detects the position of the spot, and an output signal based on the position is processed by a processing circuit as shown in FIG. 2 to measure the distance to the object.

[0003]

However, in such a conventional optical distance measuring apparatus, it is necessary to reduce the movement of the spot with respect to the movement of the object in order to extend the distance measuring range, that is, to extend the distance. For that purpose, it is necessary to reduce the angle of intersection of the optical axes of the light emitting and receiving elements. As a method of realizing it, the distance between the light emitting and receiving elements is shortened, or the intersection of the optical axes of the light emitting and receiving portions is designed to be far away.
There are two possibilities. However, the former is limited due to the size of the lens and the like, and the latter makes it difficult to measure in a range close to the device. That is, in the conventional configuration, the intersection angle of the optical axes cannot be reduced to a certain extent or more, and there is a limit to the lengthening of the distance measuring range. The present invention has been made in view of the above-mentioned conventional problems, and is configured such that the moving direction of the spot on the light receiving surface and the dividing line of the light receiving element are parallel to each other, and is measured by using the change in the spot diameter. It is an object of the present invention to provide an optical device in which the distance measurement range is expanded by performing distance measurement.

[0004]

In order to achieve the above object, the invention of claim 1 has a light projecting portion for emitting a light beam toward an object and a light receiving element for spot-receiving reflected light from the object. In the optical device including the light receiving section, the light receiving element has a light receiving surface divided into at least two regions, and a dividing line of the light receiving element is an object from the light projecting section or the light receiving section. Is arranged so as to be substantially parallel to the direction of change of the position of the spot on the light receiving surface of the reflected light that occurs when the distance to
It measures the distance to an object based on two outputs. According to a second aspect of the present invention, in an optical device including a light projecting unit that emits a light beam toward an object and a light receiving unit that has a light receiving element that spot-receives reflected light from the object, the light receiving element receives The surface is divided into at least two regions, and the dividing line of the light receiving element is on the light receiving surface of the reflected light generated when the distance from the light projecting portion or the light receiving portion to the object changes. It is configured so as to be substantially parallel to the direction in which the position of the spot changes in position, and determines whether or not the object is within a predetermined distance range based on the two outputs of the light receiving element. According to a third aspect of the present invention, in the optical device according to the second aspect, the spot of the light reflected by the object on the light receiving surface of the light receiving element is configured to straddle two divided regions, and There is provided a determination unit that takes a ratio of the outputs obtained from the regions and determines whether or not the object is within a predetermined range based on whether or not the ratio exceeds a certain value. Claim 4
In the optical device according to claim 2, whether the spot of the reflected light by the object on the light receiving surface of the light receiving element exists in only one of the two divided areas. On the basis of this, a determination means for determining whether or not the object is within a predetermined range is provided.

[0005]

According to the optical device of the present invention, a light beam is emitted from the light projecting portion toward the object, and the reflected light from the object is spot-received by the light receiving element. When the distance from the light projecting portion or the light receiving portion to the object changes, the position of the spot on the light receiving element moves and the spot diameter changes. At this time, the spot moves parallel to the dividing line of the light receiving surface, and due to the change in the spot diameter that occurs at the same time as the movement of this spot,
The two outputs of the divided light receiving element change. By detecting this change, the distance to the object can be measured. By moving the spot in parallel with the dividing line of the light receiving surface, the range intersecting with the dividing line is increased, and the distance measuring range is expanded.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A distance measuring sensor device according to a first embodiment of the present invention will be described with reference to FIGS. This device is used for the object (M
4, M5, M6), a light projecting portion including a light emitting element 1 and a light projecting lens 3 for emitting a light beam, a light receiving element 2 and a light receiving lens 4 for spot-receiving reflected light from an object.
And a light-receiving section consisting of. The light receiving element 1 is composed of a photodiode or the like, and has a light receiving surface divided into at least two regions. Then, the light receiving element 2 is configured such that the dividing line of the region and the position change direction of the light receiving spot of the reflected light that occurs when the distance from the sensor to the object changes. FIG. 4 shows the light receiving element 2.
3 shows a processing circuit for measuring the distance to the object from the output obtained by.

In the above structure, the objects are M4 to M6.
When it moves to the position, the spot moves from S4 to S6 on the light receiving surface while changing its size, as shown in FIG. At this time, since the distance between the dividing line 2d of the light receiving element 2 and the center of the spot does not change, when the spot size changes, the output ratio between the two regions of the light receiving element 2 changes. The center of the spot is biased toward one of the regions so that it does not coincide with the dividing line 2d. Since the size of the spot is uniquely determined by the distance to the object, the distance can be measured from its output ratio. In the processing circuit, the addition circuit 11, the subtraction circuit 12, and the division circuit 13 take the difference / sum of the two outputs and perform distance measurement from the value.

By the way, in the conventional triangulation method (FIG. 1), the dividing line 2e is configured to be substantially perpendicular to the moving spot, so that the spot is divided as shown in FIG. 5 (a). The range intersecting the dividing line 2e was small, and the distance measuring range was narrow. On the other hand, in the present embodiment, the moving spot is parallel to the dividing line 2d as shown in FIG. Since the spot moves when the distance to the object changes, expanding the moving range of the spot indicates expansion of the measurement range. Therefore, it can be seen that the distance measuring range can be expanded by this method. Further, since it is not necessary to change the optical axis relationship between the light emitting element 1 and the light receiving element 2 in order to extend the distance measuring range, it is possible to measure a distance range close to the device.

FIG. 6 shows a processing circuit according to the second embodiment. The optical system of Example 2 may have the same configuration as that of Example 1 (FIG. 3).
In this processing circuit, the ratio of the output obtained by the light receiving spot for each region of the light receiving element 2 is taken (the point where the ratio is taken is the same as in the first embodiment), and the ratio is set to a preset value 1
The judgment circuit 15 judges whether it is larger or smaller than 4,
From this, it is determined whether or not the object is within a predetermined distance range. When the conventional triangulation method is used, the range is narrow, and therefore the range that can be set is narrow. On the other hand, according to the present example, the range is wide, and therefore, the predetermined range for determination is set. Expands the range possible.

7 and 8 are a side view and a top view of an optical system according to the third embodiment. In the configuration of this optical system, the projection light from the light emitting element 1 is in a direction substantially perpendicular to the plane determined by the line connecting the centers of the light projecting lens 3 and the light receiving lens 4 and the distance measuring direction of the object M. -M is up or down (up in the figure)
It is shifted and projected. As a result, the spot on the light-receiving surface of the light-receiving element 2 shifts either upward or downward (depending on the projection direction of the projection beam), and the spot on the light-receiving surface is the same as in the first or second embodiment. It becomes a state. Therefore, according to this embodiment, the same effect as that of the first or second embodiment can be obtained.

FIG. 9 shows the light receiving surface of the light receiving element 2 according to the fourth embodiment, and FIG. 10 shows its processing circuit. The optical system of the present embodiment may have the same configuration as that used in the second embodiment.
The set value 14 of the output ratio of the two regions of the light receiving element in is set to "0", and the output ratio of each region is fixed to 1: 0 as shown in the figure. Then, the division circuit 13 and the set value 14 are compared by the comparison circuit 16 to obtain a detection signal. In order to change the set distance, the light receiving element 2 may be vertically movable in the configuration of FIG. 7 of the third embodiment.

In the second embodiment, the range can be expanded, but as shown in FIG. 11A, the value of output 1 / output 2 changes due to the influence of the edge (hatched portion) of the object. There is a problem of making an erroneous measurement. On the other hand, in the fourth embodiment, since the output ratio is not determined and the determination is made only based on the presence or absence of the output of each area, as shown in FIG. 11B, the spot has an edge (hatched portion) of the object. Also, since it is only checked whether the values of the outputs 1 and 2 are "0", stable detection can be performed without being affected by the edge. Further, the set distance can be varied within the same range as in the second embodiment, and the set range can be expanded as compared with the conventional device using the triangulation method.

[0013]

As described above, according to the present invention, the light reflected by the object of the projected light beam forms a spot on the light receiving surface of the light receiving element divided into at least two, and the center of the spot receives light. Since it is not on the dividing line of the element, the moving direction of the spot is almost parallel to the dividing line, the outputs from the two areas are compared, and the distance to the object is measured by the output ratio. Since the area where the spot intersects the dividing line is larger than in the conventional case, the range can be expanded. Further, since it is not necessary to change the optical axis relationship between the light emitting / receiving elements, it is possible to measure the distance even in the range close to the device.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a conventional triangulation method and a diagram showing a light receiving surface.

FIG. 2 is a circuit diagram of a processing circuit in a conventional triangulation method.

FIG. 3 is a configuration diagram of an optical system of the distance measuring sensor device according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram of a processing circuit in the same apparatus.

FIG. 5 is a diagram showing a distance measuring range according to the related art and the present embodiment.

FIG. 6 is a circuit diagram of a processing circuit according to a second embodiment.

7 is a side view of the optical system of Example 3. FIG.

FIG. 8 is a top view of the above optical system.

FIG. 9 is a diagram showing a light receiving surface in Example 4.

FIG. 10 is a circuit diagram of a processing circuit according to a fourth embodiment.

FIG. 11 is a diagram for explaining a difference in operation between the second embodiment and the fourth embodiment.

[Explanation of symbols]

 1 Light emitting element 2 Light receiving element 2d Dividing line 14 Set value 15 Judgment circuit 16 Comparison circuit

Claims (4)

[Claims] 1. A light projecting unit for emitting a light beam toward an object,
In an optical device including a light receiving section having a light receiving element for spot receiving reflected light from an object, the light receiving element has a light receiving surface divided into at least two regions, and The dividing line is configured to be substantially parallel to the position change direction of the spot on the light receiving surface of the reflected light that occurs when the distance from the light projecting portion or the light receiving portion to the object changes, An optical device which measures a distance to an object based on two outputs of the light receiving element. 2. A light projecting section for emitting a light beam toward an object,
In an optical device including a light receiving section having a light receiving element for spot receiving reflected light from an object, the light receiving element has a light receiving surface divided into at least two regions, and The dividing line is configured to be substantially parallel to the position change direction of the spot on the light receiving surface of the reflected light that occurs when the distance from the light projecting portion or the light receiving portion to the object changes, An optical device for determining whether or not an object is within a predetermined distance range based on two outputs of the light receiving element. 3. A spot of reflected light from an object on the light-receiving surface of the light-receiving element is configured to straddle two divided areas, and the ratio of the outputs obtained from the respective areas is calculated, and the ratio thereof is calculated. The optical device according to claim 2, further comprising a determination unit that determines whether or not the target object is within a predetermined range based on whether or not is greater than a certain value. 4. The object has a predetermined range based on whether or not a spot of reflected light from the object on the light receiving surface of the light receiving element exists in only one of the two divided areas. The optical device according to claim 2, further comprising a determination unit that determines whether or not the optical device is inside.