JP2002195880A - Floodlight unit and photoelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a floodlight unit for emitting parallel light having an enlarged width in a prescribed direction and having a uniform light intensity by reflecting light emitted from a light emitting means without attenuating the light quantity thereof, and to provide a photoelectric sensor. SOLUTION: This photoelectric sensor comprises the floodlight unit equipped with a collimate lens 6 and a reflection member 7, a photo receiving unit, and a light shielding state detection means. In the photoelectric sensor, the reflection member 7 has a plurality of divided reflection parts 7a disposed at intervals reduced as they are away from the optical axis of second parallel light according to the light intensity distribution of first parallel light so that the light quantity of the second parallel light emitted from an exit aperture 9 is equalized per unit area of a plane perpendicular to its optical axis. The second parallel light emitted from the floodlight unit is thereby enlarged in the perpendicular direction without attenuating the light quantity and the distribution of light intensity is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for measuring the position and size of an object to be detected by detecting a light blocking state by an object to be detected located on a measuring optical path for transmitting and receiving parallel light. The present invention relates to a light emitting unit and a photoelectric sensor.

[0002]

2. Description of the Related Art Conventionally, based on detecting a light blocking state when an object to be detected is placed on a measurement optical path for transmitting and receiving parallel light, a photoelectric sensor for measuring the position and size of the object to be detected is used. There are sensors. For example, FIG.
688 shows a configuration in which the photoelectric sensor disclosed in Japanese Patent Application Publication No. 688 is applied to a photoelectric sensor 100 for measuring a height dimension of an object. In particular, parallel light is expanded in a predetermined direction using a reflecting member. It is configured as follows.

[0005] In FIG. 5, an optical fiber 102 for propagating LED light emitted from an LED light source (not shown) is inserted and mounted in a light projecting unit 101, and a collimating lens 103 and a reflecting member 104 are integrally molded with a transparent resin inside. The optical member 105 is mounted.
As shown in FIG. 6 (a), the reflecting member 104 of the optical member 105 has a plurality of the same shape whose reflection angle is set to 90 ° with respect to the traveling direction of the incident first parallel light (described later). The divided reflecting portions 106 are arranged in a stepwise manner at equal intervals. Then, the LED light emitted from the end face of the optical fiber 102 is collimated by the collimating lens 103 of the optical member 105.
The first parallel light is reflected by the reflection member 104, and is expanded as a second parallel light that is larger than the first parallel light in a predetermined direction. The light is emitted from 101a.

Returning to FIG. 5, the light receiving unit 107 includes
Slit 108 opened in rectangular shape, condenser lens 109
And a photodiode 110. Of the second parallel light, the one that has passed through the slit 108 is received by the photodiode 110 in a state of being collected by the condenser lens 109, and An electric signal that is photoelectrically converted according to the amount of received light is output.

[0005] The signal processing unit (not shown) is formed of an electric circuit mainly composed of a microcomputer, and the relative relationship between the amount of received light and the height of the detected object is converted into data and recorded in advance. Then, the amount of light received by the photodiode 110 is detected based on the electric signal, and the height of the detected object is measured based on a comparison between the amount of received light and the data.

[0006]

As shown in FIG. 7, the light intensity distribution of the LED light emitted from the end face of the optical fiber 102 becomes larger near the optical axis and becomes smaller as the radiation angle becomes wider. It is uniform. Therefore, as shown in FIG. 6B, the light intensity distribution of the first parallel light collimated by the collimator lens 103 also becomes non-uniform as the distance from the optical axis decreases.

In this case, the second parallel light reflected by each of the divided reflecting portions 106 of the reflecting member 104 is expanded in a predetermined direction as compared with the first parallel light, but the second parallel light is reflected near the reflecting member 104. As shown in FIG. 6 (c), the light intensity distribution is non-uniform such that the maximum portions of the light intensity are arranged at equal intervals, and the light intensity of the maximum portion decreases as the distance from the optical axis increases.
Although the second parallel light is affected by a slight spread and scattering of the first parallel light before being emitted from the opening 101a of the light projecting unit 101, the light intensity distribution becomes smooth, The light intensity distribution near the portion 101a is the first
In the same manner as the parallel light, as shown in FIG. 6 (d), it remains non-uniform as the distance from the optical axis decreases.

In such a photoelectric sensor 100, since the amount of light per unit area in a plane perpendicular to the optical axis of the second parallel light is not uniform, the rate of change in the height direction of the object to be detected and the The ratio of the amount of light that is blocked by the light and no longer passes through the slit 108 (light blocking ratio) does not have a proportional relationship, and the amount of light received by the photodiode 110 and the light blocking ratio no longer have a proportional relationship, and the measurement accuracy of the height dimension decreases. Had the problem of doing so.

In the photoelectric sensor disclosed in Japanese Patent Application Laid-Open No. 7-146115, although not shown, only the light near the optical axis where the light intensity distribution of the second parallel light is substantially uniform is measured light. It is configured to emit light on the road. When this is applied to the photoelectric sensor 100, the slit 1
08, the rate of decrease of the light intensity distribution at a position distant from the optical axis of the second parallel light becomes gentle, and the amount of light per unit area on a plane perpendicular to the optical axis becomes substantially uniform. The change rate in the height direction of the object and the light-shielding rate can be in a substantially proportional relationship, and therefore, the amount of light received by the photodiode 110 and the light-shielding rate are in a substantially proportional relationship, improving the measurement accuracy of the height dimension. Seems to be able to.

However, also in this case, the slit 1
08, the difference in the light intensity of the second parallel light becomes smaller, but the relationship that the light intensity becomes smaller as the distance from the optical axis becomes smaller is not solved. However, there was a problem that the relationship was not proportional. Moreover, since the light at the end of the first parallel light is not used for the measurement, the amount of the second parallel light used for the measurement is obtained by attenuating the radiation emitted from the light emitting means,
Therefore, the amount of light received by the photodiode 110 is reduced,
There has also been a problem that the SN ratio is lowered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and therefore has as its object to increase the width of a predetermined direction by reflecting the amount of radiation emitted from a light emitting means without attenuating it. An object of the present invention is to provide a light projecting unit capable of emitting parallel light having a uniform light intensity distribution, and a photoelectric sensor including the light projecting unit.

[0012]

According to a first aspect of the present invention, there is provided a light projecting unit which emits, by a collimating lens, radiated light radiated from a light emitting means located on an optical axis and having a light intensity distribution which becomes smaller as the radiation angle becomes larger. A light projecting to collimate and to emit a second parallel light whose width in a predetermined direction is larger than that of the first parallel light by reflecting the first parallel light formed by the parallelization with a reflecting member. The unit is characterized in that the reflection member is configured such that the amount of light per unit area on a plane perpendicular to the optical axis of the second parallel light is uniform. According to such a configuration, it is possible to emit the second parallel light having a uniform light intensity distribution while maintaining a large intensity without attenuating the light amount of the first parallel light. The light-shielding dimension of the light in a predetermined direction and the reduced light amount of the second parallel light can be in a proportional relationship.

In the light projecting unit according to claim 2, the reflecting member is constituted by arranging a plurality of divided reflecting portions for dividing and reflecting the first parallel light in a stepwise manner. Are set so as to decrease as the distance from the optical axis of the first parallel light increases. According to such a configuration, by arbitrarily changing the arrangement interval and the reflection angle of the plurality of divided reflecting portions, while maintaining the light intensity distribution of the second parallel light uniform,
The magnification of the width of the second parallel light and the emission direction can be arbitrarily set.

According to a third aspect of the present invention, in the photoelectric sensor, the reflecting member is configured by arranging a plurality of divided reflecting portions for dividing and reflecting the first parallel light in a stepwise manner. The area is set so as to increase as the distance from the optical axis of the first parallel light increases. Even with such a configuration, the same effects as those of the second aspect can be obtained by arbitrarily changing the areas and the reflection angles of the plurality of divided reflecting portions.

According to a fourth aspect of the present invention, there is provided a photoelectric sensor, wherein the light projecting unit according to any one of the first to third aspects and the second parallel light emitted from the light projecting unit are condensed by a condenser lens. A light receiving unit for receiving the condensed light by a light receiving means; a slit means for regulating a region of the second parallel light received by the light receiving means into a rectangular slit shape; And a light-shielding state detecting means for detecting a light-shielding state of a measuring optical path formed between the light projecting unit and the light receiving unit based on the amount. According to such a configuration, since the second parallel light having a uniform light intensity distribution is emitted from the light projecting unit, it is possible to make the light blocking ratio of the measuring optical path and the amount of light received by the light receiving means proportional. As a result, the measurement accuracy in the light-shielded state can be improved. Moreover, since the light intensity of the second parallel light is sufficiently high, the SN ratio can be improved. Further, since the width of the second parallel light is wider than that of the first parallel light, the measurement range can be increased.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment] An embodiment in which the photoelectric sensor of the present invention is applied to a photoelectric sensor for measuring the height of an object to be detected will be described below with reference to FIGS. explain.

FIG. 2 shows the structure of the photoelectric sensor 1. In FIG. 2, the photoelectric sensor 1 is installed on the side of the line 2 through which objects to be detected having different heights flow, as follows.

First, a box-shaped case 3 is provided on one side of the line 2, and a circular opening 4 is provided in an upper surface 3 a of the case 3. The optical fiber 5 is inserted and mounted such that the end face of the optical fiber 5 is located inside the case. This optical fiber 5
Is for transmitting LED light emitted from an LED light source (not shown), and a light emitting means is constituted by these LED light sources and an optical fiber.

In the case 3, there is provided an optical member 8 (described later) in which a collimating lens 6 and a reflecting member 7 are integrally formed of a transparent resin. This optical member 8 is
The collimator lens 6 is positioned so that the center of the collimator lens 6 is positioned on the optical axis of the LED light that is emitted light emitted from the end face of the optical fiber 5. Then, the reflecting member 7 is as shown in FIG.
As shown in FIG. 7, a plurality of divided reflecting portions 7a having the same pitch and having a reflection angle of 90 ° with respect to the traveling direction of the incident first parallel light (described later) are arranged stepwise. . Here, the pitch is the length of the portion where the divided reflecting portion 7a reflects the first parallel light. The arrangement interval of the divided reflecting portions 7a perpendicular to the direction parallel to the first parallel light is such that the amount of second parallel light (described later) emitted from the exit 9 is perpendicular to the optical axis. In accordance with the light intensity distribution of the first parallel light, the distance is set to be smaller as the distance from the optical axis of the second parallel light is increased so as to be uniform per unit area of the surface. An anti-reflection film is applied to the surfaces of the collimating lens 6 and the exit 9.

Returning to FIG. 2, an opening 10 is provided in a front portion 3c of the case 3 facing the line 2 side. The LED light emitted from the end face of the optical fiber 5 is collimated by the collimator lens 6 and emitted as first parallel light, and the first parallel light is reflected by the reflection member 7 and the aperture 10 From the first parallel light toward the line 2 side, and is emitted as a second parallel light whose width is expanded in the vertical direction than the first parallel light. Thus, the light emitting unit 11 is configured by the light emitting unit and the optical member 8.

Next, a rectangular case 12 is provided on the other side of the line 2 facing the light projecting unit 11, and a front portion 1 of the case 12 facing the line 2 is provided.
2a, a slit 13 is formed as a slit means which is opened in a rectangular shape such that its longitudinal direction is oriented in the vertical direction and its center is located at the optical axis of the second parallel light.

Further, a condensing lens 14 having an anti-reflection film on the surface thereof is disposed inside the case 12 so that the central portion is located on the extension of the optical axis. At a focal position of 14, a photodiode 15 as a light receiving means is mounted.

In the photodiode 15, all of the second parallel light passing through the slit 13 is collected, and an electric signal photoelectrically converted according to the light intensity distribution of the collected light is output. ing. In this manner, the slit 13, the condenser lens 14, and the photodiode 1
5, the light receiving unit 16 is constituted.

Although not shown, the light-shielding state detecting circuit, which is a light-shielding state detecting means, is constituted by an electric circuit mainly composed of a microcomputer, and the height of the object to be detected is determined based on an electric signal received from the photodiode 15. A measurement of the dimension is made. Then, information on the measured height of the detected object is transmitted to a line management device (not shown), and is used for controlling the division of the detected object. As described above, the photoelectric sensor 1 is configured by the light projecting unit 11, the light receiving unit 16, and the light blocking state detecting circuit.

<Description of Operation of Optical Member 8> Next, the operation of the optical member 8 will be described. The light intensity distribution of the LED light emitted from the end face of the optical fiber 5 is, as shown in FIG.
The light intensity distribution of the first parallel light that is collimated by the collimating lens 6 is also non-uniform such that it becomes larger as the optical axis and becomes smaller as the radiation angle becomes larger.
As shown in FIG. 1B, the distance becomes non-uniform as the distance from the optical axis decreases.

By the way, each divided reflecting portion 7a of the reflecting member 7
As described above, the arrangement interval of the first parallel light is set such that the light amount of the second parallel light emitted from the emission port 9 becomes uniform per unit area of a plane perpendicular to the optical axis. According to the intensity distribution, the distance is set to be smaller as the distance from the optical axis of the second parallel light increases. Therefore, the light intensity distribution of the second parallel light near the reflecting member 7 is as shown in FIG.
As shown in (1), although the local maximum of the light intensity decreases as the distance from the optical axis increases, the interval between the local maximums becomes closer.

The second parallel light is uniformed under the influence of a slight spread or scattering of the first parallel light before it is emitted from the opening 10 of the light projecting unit 11, and the second parallel light is uniformed. The light intensity distribution in the vicinity of 10 becomes uniform from the optical axis to the periphery as shown in FIG. That is,
The second parallel light emitted from the light projecting unit 11 has a uniform amount of light per unit area on a surface perpendicular to the optical axis.

<Description of Operation of Photoelectric Sensor 1> Next, the operation of the photoelectric sensor 1 will be described. The second parallel light emitted from the opening 10 of the light projecting unit 11 is emitted toward the slit 13 of the light receiving unit 16 while forming an optical path for measurement on the line 2. Then, only the second parallel light having the same width as the slit 13 passes through the slit 13, is collected by the condenser lens 14, and the collected light is received by the photodiode 15. Subsequently, in the photodiode 15, an electric signal photoelectrically converted according to the light intensity of the condensed light is output to the light-shielded state detection circuit.

In the light-shielded state detection circuit, the amount of light received by the photodiode 15 is detected based on the received electric signal. In this case, since the light intensity distribution of the second parallel light is uniform on a plane perpendicular to the optical axis, the amount of light received by the photodiode 15 is reduced when the detected object passes through the measurement optical path. It is proportional to the ratio of the amount of light blocked (the light blocking ratio) according to the height of the detection object. Then, the light receiving rate of the light receiving amount detected in a state where light is not blocked (a state in which 100% of the second parallel light is incident on the slit 13) is set to 100%,
The height dimension of the detected object is measured by calculating the light receiving ratio detected when the light is blocked by the detected object.

As described above, in the present embodiment, when the plurality of divided reflecting portions 7a are arranged in a stepwise manner, the amount of the second parallel light emitted from the emission port 9 is determined by the unit of the surface perpendicular to the optical axis. The reflecting member 7 is configured such that the arrangement interval becomes smaller as the distance from the optical axis of the second parallel light increases in accordance with the light intensity distribution of the first parallel light so that the light is uniform per area. Therefore, the light shielding dimension in the vertical direction of the second parallel light and the reduced light amount of the second parallel light can be in a proportional relationship.

This makes it possible to make the light blocking ratio of the measuring optical path and the amount of light received by the photodiode 15 proportional to each other, thereby improving the measurement accuracy of the height of the object to be detected. Moreover, since the light intensity of the second parallel light is sufficiently high, the SN ratio can be improved. Further, since the diameter of the second parallel light is larger than that of the first parallel light, the measurement range can be enlarged.

In the present embodiment, the reflection angle of the divided reflecting portion 7a is set to 90 °. However, the present invention is not limited to this. By setting the reflection angle arbitrarily, the second parallel light can be set. The emission direction may be set arbitrarily. Further, when changing the enlargement ratio of the width of the second parallel light with respect to the first parallel light in the predetermined direction, the pitch of each divided reflecting portion 7a may be changed.

[Other Embodiments] The optical members are not limited to those shown in the present embodiment, but may be modified as follows.

FIG. 3 shows the structure of an optical member 22 in which a collimating lens 20 and a reflecting member 21 are integrally formed in the same manner as the optical member 8 of the present embodiment. However, the reflecting member 21 of the optical member 22 is different from that of the present embodiment in that the space between the divided reflecting portions 7a is formed by a plane parallel to the optical axis of the first parallel light. Each of the divided reflecting portions 21a is arranged stepwise like a saw blade so that a part of each of the divided reflecting portions 21a overlaps with the optical axis. With such a configuration, the same effect as that of the present embodiment can be obtained.

FIG. 4 shows an optical member 2 in which a collimating lens 23 and a reflecting member 24 are provided separately.
5 shows the configuration of FIG. The split reflecting portion 24a of the optical member is configured in a stepwise manner as in the present embodiment, and the surface thereof is subjected to metal evaporation. With such a configuration, the same effect as that of the present embodiment can be obtained. When it is necessary to change, for example, the diameter of the collimating lens 23 according to the light emitting means, the collimating lens 23 and the reflecting member 24 are separately provided. The same member 24 can be used, and the economical efficiency in the manufacturing process of the optical member 25 can be improved.

Further, although not shown, the reflecting member has an area of the divided reflecting portion (the area of the divided reflecting portion instead of decreasing the arrangement interval of the divided reflecting portion away from the optical axis of the first parallel light as in this embodiment). The area of the first parallel light reflecting portion) may be made larger as the distance from the optical axis of the first parallel light increases (the invention according to claim 2), and the arrangement interval and area of these divided reflecting portions may be increased. It may be configured to serve both adjustments. With such a configuration, the same effect as that of the present embodiment can be obtained.

The present invention is not limited to the embodiment described above and shown in the drawings.
Extension is possible. In the embodiment of the present invention, the size of each of the divided reflecting portions is the same, but the size is not limited to this, and the size may be changed according to the light intensity distribution of the first parallel light.

In the embodiment of the present invention, the light emitting means is applied to the LED light source for emitting LED light from the end face of the optical fiber. However, the present invention is not limited to this. Good. Also, LE
Instead of the D light source, for example, a laser light source, a general light bulb, or the like may be applied. In short, any light source that emits radiation light whose light intensity distribution decreases as the radiation angle increases.

In the embodiment of the present invention, the light receiving means is applied to the photodiode. However, the present invention is not limited to this. For example, the light receiving means may be applied to a one-dimensional light receiving element or a two-dimensional light receiving element. In this case, since these light receiving elements themselves have the function of the slit means, the slit can be omitted. Further, for example, the light receiving unit may be configured such that the light condensed by the condensing lens is once received by the optical fiber, and the light propagated by the optical fiber is received by the light receiving element. Further, in this embodiment, the photoelectric sensor is applied to a sensor for measuring a height dimension. However, by selecting the light receiving means as described above, the length of the object to be detected can be measured or the two-dimensional image of the object to be detected can be measured. The present invention may be applied to a device that measures complicated shape recognition.

In the embodiment of the present invention, the light receiving unit is provided with the second
Although the slit is provided at the position where the parallel light is incident, the present invention is not limited to this. The slit may be provided at any position on the optical path formed between the light emitting unit and the light receiving unit. In addition, the slit may be provided as needed, and the point is that the optical system of the photoelectric sensor is set so that the region of the second parallel light received by the photodiode is restricted to a rectangular slit shape. I just need.

In the embodiment of the present invention, the diameter of the second parallel light is enlarged in the vertical direction. However, the present invention is not limited to this, and the divided reflecting portions of the reflecting member are arranged two-dimensionally. Thus, the image may be enlarged two-dimensionally in the vertical and horizontal directions.

[0042]

As is apparent from the above description, the light projecting unit of the present invention has a structure in which the interval between the plurality of divided reflectors is reduced as the distance from the optical axis of the first parallel light is increased. With this configuration, the light shielding dimension in the vertical direction of the second parallel light and the reduced light amount of the second parallel light are maintained while maintaining a large light intensity without attenuating the light amount of the radiated light emitted from the light emitting unit. It can be proportional. By configuring the photoelectric sensor with the light projecting unit, the light receiving unit and the light shielding state detecting means, the light shielding rate and the amount of light received by the light receiving means can be made to have a proportional relationship, thereby improving the measurement accuracy of the light shielding state. be able to.

[Brief description of the drawings]

FIG. 1 is an optical configuration diagram of an optical member according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a photoelectric sensor.

FIG. 3 is a view corresponding to FIG. 1, showing another embodiment of the present invention.

FIG. 4 is a diagram corresponding to FIG. 1;

FIG. 5 is a diagram corresponding to FIG. 2 showing a conventional example.

FIG. 6 is a diagram corresponding to FIG. 1;

FIG. 7 is a light intensity distribution diagram of LED light emitted from an optical fiber end face.

[Explanation of symbols]

In the drawings, 1 is a photoelectric sensor, 5 is an optical fiber (light emitting means), 6, 20, and 23 are collimating lenses, 7, 21, and
24 is a reflection member, 7a, 21a and 24a are divided reflection portions,
8, 22, 25 are optical members, 11 is a light emitting unit, 13
Is a slit (slit means), 14 is a condenser lens, 15
Denotes a photodiode (light receiving means), and 16 denotes a light receiving unit.

Claims (4)

[Claims] 1. A collimating lens collimates radiated light radiated from a light emitting means and having a light intensity distribution that becomes smaller as the radiation angle increases, and a first parallel light formed by the collimation is reflected by a reflecting member. In the light projecting unit that emits a second parallel light whose width in a predetermined direction is larger than that of the first parallel light by reflecting the light, the reflecting member is perpendicular to an optical axis of the second parallel light. A light projecting unit characterized in that a light amount per unit area on a surface is configured to be uniform. 2. The reflecting member is configured by arranging a plurality of divided reflecting portions for dividing and reflecting the first parallel light in a stepwise manner. 2. The light projecting unit according to claim 1, wherein the light emitting unit is set so as to become smaller as the distance from the optical axis of the parallel light increases. 3. The reflecting member is configured by arranging a plurality of divided reflecting portions for dividing and reflecting the first parallel light in a stepwise manner. 2. The light emitting unit according to claim 1, wherein the light emitting unit is set to increase as the distance from the optical axis of the parallel light increases. 4. The light projecting unit according to claim 1, wherein said second parallel light emitted from said light projecting unit is condensed by a condensing lens, and said condensed light is condensed. A light receiving unit for receiving light by the light receiving means, a slit means for regulating a region of the second parallel light received by the light receiving means into a rectangular slit shape, and a light receiving amount received by the light receiving unit,
A photoelectric sensor comprising: a light-shielding state detecting unit that detects a light-shielding state of a measurement optical path formed between the light projecting unit and the light receiving unit.