JP2004144694A - Optical detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical detector of a small size and low-cost, capable of radiating the light of even and high intensity distribution toward an object to be detected. <P>SOLUTION: The light emitted from a light emitting element 13 in a light projection part 10 is converted into a parallel light by a lens 14. It enters an incidence surface 151 of a prism 15 and is refracted on the incidence surface 151, and then is emitted from an outgoing surface 152 through a projection window 12. The light 30 having entered the incidence surface 252 of the prism 25 through a light receiving window 22 of a light receiving part 20 is refracted at an outgoing surface 251, and then condensed with a lens 24, which is received by a light receiving element 23. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical detector that projects light on a detection area and detects information about an object to be detected based on feedback light from the detection area.
[0002]
[Prior art]
Conventionally, by projecting light from a light source onto an object and detecting the distribution of the amount of transmitted light or reflected light, the presence or absence of an object, dimensions of an object, an interval between objects, an object position, an object shape, an object An optical detector such as a photoelectric sensor or an optical scanner for detecting an image or the like attached to the image is used.
[0003]
FIG. 8 is a schematic diagram showing a basic configuration of a conventional transmission type optical detector.
The optical detector of FIG. 8 includes a light projecting unit 50 and a light receiving unit 60. The light projecting unit 50 includes a light projecting circuit 51, a light emitting element 52, and a lens 53. The light emitting element 52 is driven by the light emitting circuit 51. The light emitted from the light emitting element 52 is converted into parallel light by the lens 53 and is projected on the detected object 500 and the light receiving unit 60.
[0004]
The light receiving unit 60 includes a light receiving circuit 61, a light receiving element 62, and a lens 63. The transmitted light from the detection area 501 is focused on the light receiving element 62 by the lens 63. The light receiving element 62 outputs the amount of received light as an electric signal. The light receiving circuit 61 detects the presence / absence, size, shape, and the like of the detected object 500 in the detection area 501 based on the electric signal output from the light receiving element 62.
[0005]
FIG. 9A is a schematic diagram illustrating an example of a conventional optical detector, and FIG. 9B is a diagram illustrating a relationship between a position of a light irradiation surface and light intensity (see Patent Document 1).
[0006]
In FIG. 9, a light emitting body 101 is composed of, for example, an LED (light emitting diode) and emits light. Light generated by the light emitter 101 is transmitted to the lens 103 through the optical fiber 102. The lens 103 converts light emitted from the optical fiber 102 into parallel light having a certain width. The parallel light is reflected by the reflection surface 104.
[0007]
The parallel light 112 reflected by the reflection surface 104 is blocked by the detected object 105, and light not blocked by the detected object 105 enters the photodetector 106. When light enters the photodetector 106, the photodetector 106 generates a light receiving signal corresponding to the incident light and outputs the signal to the comparison circuit 107. Further, the reference value generation circuit 108 generates a reference signal and outputs it to the comparison circuit 107.
[0008]
The comparison circuit 107 compares the light reception signal output from the photodetector 106 with the reference signal output from the reference value generation circuit 108, and determines whether or not the detected object 105 exists in the area of the parallel light 112. judge. Next, the comparison circuit 107 outputs the determination result as a detection signal.
[0009]
Generally, the intensity of the emitted light of the LED shows an intensity distribution that is strong at the center and becomes weaker as the distance from the center increases. Accordingly, as shown in FIG. 9B, the intensity of the light applied to the object to be detected 105 is not uniform in the light beam, but varies depending on the position in the light beam. When the object 105 is present, the amount of change in the amount of light due to the light being blocked by the detected object 105 is small. Therefore, depending on the position of the detected object 105, the detection sensitivity and the detection accuracy may be reduced.
[0010]
In addition, since the light intensity varies depending on the position in the light beam, the amount of light incident on the photodetector 106 varies depending on the position in the light beam even if the detection target 105 has the same size. Therefore, the size of the detected object 105 cannot be detected.
[0011]
Furthermore, in order to increase the width of light, it is necessary to use a large lens 103. When the lens is made of resin, the lens is deformed by heat or the like. However, since it is not easy to process the shape of the lens surface with high precision, a glass lens is expensive. Therefore, cost reduction cannot be achieved.
[0012]
Note that there is a laser parallel light linear sensor using a laser diode as the light emitting body 101. In this laser parallel light linear sensor, since the intensity of the laser light is high, only the region where the intensity of the laser light is relatively uniform can be used. Thereby, the detection target object 105 can be irradiated with parallel light having relatively uniform intensity. However, a laser parallel light linear sensor using a laser diode as the light emitting body 101 becomes large and expensive.
[0013]
FIG. 10 is a schematic diagram showing another example of a conventional optical detector (see Patent Document 1).
[0014]
In FIG. 10, light generated from a luminous body 201 is transmitted through an optical fiber 202, becomes radiated light 211, and is incident on a lens 203. The radiation light 211 that has entered the lens 203 becomes parallel light 212 and is applied to the reflection member 213. The parallel light 212 applied to the reflecting member 213 is split and reflected by a large number of total reflection surfaces 214 formed on the surface of the reflecting member 213. The width W2 of the reflected light 215 is set to be larger than the width W1 of the parallel light 212, and is applied to the detected object.
[0015]
[Patent Document 1]
JP-A-7-146115
[0016]
[Problems to be solved by the invention]
In the conventional optical detector of FIG. 10, since the width of the light applied to the object to be detected can be increased, the light at the central portion where the intensity distribution is substantially constant among the light generated by the light emitting body 201 can be increased. Can be irradiated on the object to be detected. This makes it possible to make the intensity distribution of the light applied to the detected object substantially constant irrespective of the position.
[0017]
However, a plurality of sets of peaks and valleys are generated in the light intensity distribution at a pitch corresponding to the number of reflecting surfaces 214 of the reflecting member 213. In this case as well, since the intensity of light applied to the detected object differs depending on the position in the light beam, if there is a small detected object at a position where the light intensity is weak, the light may be blocked by the detected object. And the amount of change in the amount of light is reduced. Therefore, depending on the position of the detected object, the detection sensitivity and the detection accuracy may decrease.
[0018]
Further, in the valley portion of the light intensity distribution, the light generated by the light emitter 201 is reflected in another direction without irradiating the detection target object, so that the light amount is wasted. Thereby, the intensity of light is reduced as a whole, and the detection sensitivity is reduced.
[0019]
An object of the present invention is to provide an optical detector that can irradiate light having a uniform and high intensity distribution to an object to be detected and that can be reduced in size and cost.
[0020]
Means for Solving the Problems and Effects of the Invention
An optical detector according to a first aspect of the present invention is an optical detector that projects light on a detection area and detects information about an object to be detected based on feedback light from the detection area, and a light source that generates light. And a light projecting prism for refracting light generated by the light source and projecting the light to the detection area, wherein the light projecting prism is configured to receive the light generated by the light source at an incident angle smaller than 90 degrees. And a second surface which forms a predetermined angle with respect to the first surface and emits light refracted by the first surface.
[0021]
In the optical detector according to the present invention, the light generated by the light source is incident on the first surface of the light projecting prism at an incident angle smaller than 90 degrees, is refracted on the first surface, and is refracted on the second surface. Emitted from the surface. Thereby, the width of the light emitted from the light emitting element is enlarged by being refracted by the first surface of the light projecting prism.
[0022]
In this case, of the light emitted from the light-emitting element, light having substantially constant intensity within a certain region centered on the optical axis is used by being expanded by the light projecting prism, and has a uniform intensity distribution. Light having a wide width is obtained. As a result, information about the detected object can be detected more accurately.
[0023]
Further, since the light projecting prism has a simple shape and is easy to process, it can be manufactured at low cost. Therefore, the cost of the optical detector can be reduced.
[0024]
Furthermore, by making the light incident on the first surface of the light projecting prism at an incident angle smaller than 90 degrees, the width of the light emitted from the light emitting element can be enlarged using a small light projecting prism. Therefore, the size of the optical detector can be reduced.
[0025]
An optical detector according to a second aspect of the present invention is the optical detector according to the first aspect, wherein the light refracted by the first surface of the light projecting prism is perpendicularly incident on the second surface. The angle between the light generated by the light source and the first surface of the light projecting prism and the angle between the first surface and the second surface of the light projecting prism are set. It is.
[0026]
In this case, the light refracted by the first surface of the light projecting prism is emitted perpendicularly from the second surface. This allows the light to be emitted from the emission surface while maintaining the width of the light expanded on the first surface of the light projecting prism.
[0027]
An optical detector according to a third aspect of the present invention is an optical detector for projecting light onto a detection area and detecting information about an object to be detected based on light returned from the detection area, wherein the light source generates light. And a light projecting prism for refracting light generated by the light source and projecting the light to the detection area, wherein the light projecting prism is configured to receive the light generated by the light source at an incident angle smaller than 90 degrees. And a second surface which forms a predetermined angle with respect to the first surface, and on which the light refracted by the first surface is incident, and which reflects the light incident on the second surface. Are provided on the second surface, and the light reflected by the reflection surface is emitted from the first surface.
[0028]
In the optical detector according to the present invention, the light generated by the light source is incident on the first surface of the light projecting prism at an incident angle smaller than 90 degrees, is refracted on the first surface, and is refracted on the second surface. Incident on the surface. Light incident on the second surface is reflected by the reflection surface and emitted from the first surface. Thereby, the width of the light emitted from the light emitting element is enlarged by being refracted by the first surface of the light projecting prism.
[0029]
In this case, of the light emitted from the light-emitting element, light having substantially constant intensity within a certain region centered on the optical axis is used by being expanded by the light projecting prism, and has a uniform intensity distribution. Light having a wide width is obtained. As a result, information about the detected object can be detected more accurately.
[0030]
Further, since the light projecting prism has a simple shape and is easy to process, it can be manufactured at low cost. Therefore, the cost of the optical detector can be reduced.
[0031]
Furthermore, by making the light incident on the first surface of the light projecting prism at an incident angle smaller than 90 degrees, the width of the light emitted from the light emitting element can be enlarged using a small light projecting prism. Therefore, the size of the optical detector can be reduced.
[0032]
Further, the light refracted by the first surface is reflected by the reflection surface provided on the second surface and emitted from the first surface, so that the first surface and the second surface of the light projecting prism are formed. Angle can be reduced. Thus, the size of the light projecting prism can be further reduced. As a result, the size of the optical detector can be further reduced.
[0033]
An optical detector according to a fourth aspect of the present invention is the optical detector according to the third aspect, wherein the light source is generated by the light source such that the light reflected by the reflection surface is perpendicularly incident on the first surface. The angle between the applied light and the first surface of the light projecting prism and the angle between the first surface and the second surface of the light projecting prism are set.
[0034]
In this case, the light reflected on the reflecting surface is emitted perpendicularly from the first surface. This allows the light to be emitted from the emission surface while maintaining the width of the light expanded on the first surface of the light projecting prism.
[0035]
An optical detector according to a fifth invention is the optical detector according to any one of the first to fourth inventions, wherein the light generated by the light source is converted into parallel light to convert The optical device further includes an optical member that is incident on the first surface.
[0036]
In this case, parallel light having a large width can be projected by converting the light generated by the light source into parallel light and entering the first surface of the light projecting prism.
[0037]
An optical detector according to a sixth aspect of the present invention is the optical detector according to any one of the first to fifth aspects, wherein the light projecting prism has a substantially triangular shape having the first surface as an oblique side. A light-emitting circuit substrate having a substantially triangular shape having a hypotenuse and provided with a light-emitting circuit for driving a light source, a light-emitting prism and a light-emitting casing for housing the light-emitting circuit substrate; And the light projecting prism and the light projecting circuit board are arranged in the light projecting casing so as to face each other on the oblique side.
[0038]
In this case, since the light projecting prism and the light projecting circuit board are arranged in the light projecting casing so as to face each other on the oblique side, the space in the light projecting casing is effectively used. Thereby, the size of the optical detector can be further reduced.
[0039]
An optical detector according to a seventh aspect of the present invention is the optical detector according to any one of the first to sixth aspects, wherein the optical detector for refracting return light based on light projected from the light projecting prism is provided. A prism, and a light receiving element that receives the light refracted by the light receiving prism, wherein the light receiving prism forms a predetermined angle with respect to the third surface on which the return light is incident and the third surface; And a fourth surface that refracts light from the third surface and emits the light to the light receiving element.
[0040]
In this case, return light based on the light projected from the light projecting prism enters the third surface of the light receiving prism, is refracted by the fourth surface, and is emitted to the light receiving element. Thereby, light having a wide width can be guided to the light receiving element by the small light receiving prism. As a result, information on the detected object can be detected more accurately, and the size of the optical detector can be further reduced.
[0041]
Further, the light receiving prism has a simple shape and is easy to process, so that it can be manufactured at low cost. Therefore, the cost of the optical detector can be further reduced.
[0042]
An optical detector according to an eighth invention is the optical detector according to the seventh invention, wherein the light-receiving prism has a substantially triangular shape having the fourth surface as a hypotenuse, and a substantially triangular shape having a hypotenuse. A light-receiving circuit substrate having a shape and provided with a light-receiving circuit for processing a signal output from the light-receiving element; and a light-receiving casing that houses the light-receiving prism and the light-receiving circuit substrate. The prism and the light-receiving circuit substrate are disposed in the light-receiving casing so as to face each other on the oblique side.
[0043]
In this case, since the light receiving prism and the light receiving circuit substrate are arranged in the light receiving casing so as to face each other on the oblique side, the space in the light receiving casing is effectively used. Thereby, the size of the optical detector can be further reduced.
[0044]
An optical detector according to a ninth aspect of the present invention is an optical detector for projecting light onto a detection area and detecting information about an object to be detected based on light returned from the detection area, wherein the light source generates light. A light projecting prism having a substantially triangular shape and refracting light generated by the light source and projecting the light to the detection area; and a light projecting circuit having a substantially triangular shape and driving the light source are provided. A light projecting circuit board; and a casing for housing the light projecting prism and the light projecting circuit board. The light projecting prism and the light projecting circuit board are disposed inside the light projecting casing such that they face each other at an oblique side. It is arranged in.
[0045]
In the optical detector according to the present invention, the light source is driven by the light emitting circuit, and light is generated by the light source. The light generated by the light source is refracted by the light projecting prism and projected on the detection area.
[0046]
In this case, since the light projecting prism and the light projecting circuit board are arranged in the light projecting casing so as to face each other on the oblique side, the space in the light projecting casing is effectively used. Thus, the size of the optical detector can be reduced.
[0047]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a perspective view showing the internal structure of an optical detector according to one embodiment of the present invention. FIG. 2 is a plan view showing the internal structure of the light projecting unit of the optical detector of FIG.
[0048]
The optical detector of FIG. 1 includes a light projecting unit 10 and a light receiving unit 20. The light projecting unit 10 includes a substantially rectangular casing 11. A light projecting window 12 is formed on one side surface of the casing 11. The casing 11 houses a light emitting element 13 composed of a laser diode, a lens 14, a prism 15, and a light emitting circuit board 16.
[0049]
The light emitting element 13 is disposed at one corner in the casing 11 so that the optical axis is substantially along the diagonal direction of the casing 11. The lens 14 is arranged in front of the light emitting surface of the light emitting element 13.
[0050]
The prism 15 is made of glass and has a right triangle shape. The oblique side of the prism 15 becomes the incident surface 151, and one side of the two sides that are perpendicular to each other becomes the exit surface 152. The prism 15 is disposed in the casing 11 such that the incident surface 151 is substantially along the diagonal direction of the casing 11 and the exit surface 152 faces the light projecting window 12. Further, the light projecting circuit board 16 has a right-angled triangular shape, and is disposed in the casing 11 such that the oblique side faces the incident surface 151 of the prism 15. The light emitting circuit board 16 is provided with a light emitting circuit for driving the light emitting element 13.
[0051]
The light receiving unit 20 includes a substantially square casing 21. A light receiving window 22 is formed on one side surface of the casing 21. In the casing 21, a light receiving element 23 composed of a photodiode, a lens 24, a prism 25, and a light receiving circuit board 26 are housed.
[0052]
The light receiving element 23 is disposed at one corner in the casing 21 so that the optical axis is substantially along the diagonal direction of the casing 21. The lens 24 is arranged in front of the light receiving surface of the light receiving element 23.
[0053]
The prism 25 is made of glass and has a right triangle shape. The oblique side of the prism 25 becomes the emission surface 251, and one side of the two sides that are perpendicular to each other becomes the incident surface 252. The prism 25 is disposed in the casing 21 such that the emission surface 251 is substantially along the diagonal direction of the casing 21 and the incidence surface 252 faces the light receiving window 22. The light receiving circuit board 26 has a right-angled triangular shape, and is arranged in the casing 21 such that the oblique side faces the emission surface 251 of the prism 25. The light receiving circuit board 26 is provided with a light receiving circuit for outputting a detection result by processing a signal output from the light receiving element 23.
[0054]
Light 30 emitted from the light emitting element 13 in the light projecting unit 10 is converted into parallel light by the lens 14, enters the incident surface 151 of the prism 15, is refracted by the incident surface 151, and transmits through the emission surface 152. The light is emitted from the light emitting window 12 to the detection area. The light 30 incident on the incident surface 252 of the prism 25 through the light receiving window 22 of the light receiving unit 20 is refracted by the light emitting surface 251 and emitted, collected by the lens 24, and received by the light receiving element 23.
[0055]
In the present embodiment, the light emitting element 13 corresponds to a light source, the prism 15 corresponds to a light projecting prism, the incident surface 151 corresponds to a first surface, and the emission surface 152 corresponds to a second surface. The lens 14 corresponds to an optical member, and the light emitting circuit board 16 corresponds to a light emitting circuit board. Further, the prism 25 corresponds to a light receiving prism, the incident surface 252 corresponds to a third surface, the emission surface 251 corresponds to a fourth surface, the light receiving circuit board 26 corresponds to a light receiving circuit board, 21 corresponds to a light-receiving casing.
[0056]
3A and 3B are diagrams for explaining the principle of the optical detector shown in FIG. 1, wherein FIG. 3A shows the intensity distribution of light emitted from the prism, and FIG. This shows the relationship with the emitted light, and (c) shows the intensity distribution of the light emitted from the light emitting element. In FIG. 3, illustration of the lens 14 in FIGS. 1 and 2 is omitted. FIG. 4 is a diagram for explaining refraction of light.
[0057]
In FIG. 4, the refractive index of the medium 301 is n ₁ And the refractive index of the medium 302 is n ₂ And Light has a refractive index n ₁ From the medium 301 of n ₂ When the light enters the medium 302, the light is refracted at the boundary surface between the medium 301 and the medium 302. At this time, the following relationship exists between the incident angle i and the refraction angle t.
[0058]
n ₁ sin (i) = n ₂ sin (t)
Therefore, the refractive index n of the medium 301 ₁ Is the refractive index n of the medium 302 ₂ 4A, the incident angle i of the incident light 31 on the interface between the medium 301 and the medium 302 is larger than the refraction angle t of the emitted light 32, as shown in FIG. On the other hand, the refractive index n of the medium 301 ₁ Is the refractive index n of the medium 302 ₂ 4B, the incident angle i of the incident light 31 on the interface between the medium 301 and the medium 302 becomes smaller than the refraction angle t of the outgoing light 32, as shown in FIG.
[0059]
In FIG. 3B, the light emitting element 13 is arranged so that the optical axis of the emitted light and the incident surface 151 of the prism 15 make an angle smaller than 90 degrees. Thereby, as shown by the arrow, the light emitted from the light emitting element 13 is obliquely incident on the incident surface 151 of the prism 15. The refractive index of the prism 15 is larger than the refractive index of air. Therefore, the light incident on the prism 15 is refracted on the incident surface 151 such that the refraction angle t is smaller than the incident angle i as shown in FIG. As a result, the width of the light emitted from the light emitting element 13 is enlarged by being refracted by the incident surface 151 of the prism 15.
[0060]
Here, the angle of incidence i of the light on the incident surface 151 and the angle between the incident surface 151 and the exit surface 152 of the prism 15 such that the light refracted on the incident surface 151 of the prism 15 is perpendicularly incident on the exit surface 152. θ is set. Thereby, the light refracted by the incident surface 151 of the prism 15 is emitted perpendicularly from the emission surface 152.
[0061]
As shown in FIG. 3C, the intensity distribution of the light emitted from the light emitting element 13 is substantially constant and has a maximum intensity near the optical axis, and the intensity decreases as the distance from the optical axis increases. Accordingly, by using light having substantially constant intensity in a certain region L centered on the optical axis among the light emitted from the light emitting element 13 and using it by the prism 15, as shown in FIG. A light beam having a uniform intensity distribution and a wide width can be obtained. As a result, it is possible to more accurately detect information such as the presence / absence, size, and shape of the detected object.
[0062]
In this case, the width of the light enlarged by the prism 15 is determined by the incident angle i of the light on the incident surface 151 of the prism 15. By making the incident angle i close to 90 degrees, the width of light can be infinitely expanded in principle.
[0063]
Also, as described above, the angle of incidence i of the light on the incident surface 151 or the angle between the incident surface 151 and the exit surface 152 so that the light refracted on the incident surface 151 of the prism 15 is not refracted on the exit surface 152. By setting θ, it is possible to emit light from the emission surface 152 while maintaining the width of the light enlarged on the incident surface 151.
[0064]
As in the optical detector of FIG. 1, it is preferable that the light emitted from the light emitting element 13 be converted into parallel light by the lens 14 and be incident on the incident surface 151 of the prism 15. This makes it possible to project parallel light having a large width.
[0065]
The incident angle of light on the incident surface 151 of the prism 15 can be set to any angle except 90 degrees. Also in that case, the width of light can be enlarged.
[0066]
The angle between the incident surface 151 of the prism 15 and the incident light and the angle between the output surface 152 of the prism 15 and the output light depend on the amount of light to be projected, the size of the light receiving element 23, the magnification of the light width, and the like. It can be set arbitrarily.
[0067]
As described above, in the optical detector according to the present embodiment, light having a uniform, high intensity distribution and a wide width is projected from the light projecting unit 10 to the detection region. Therefore, information such as the presence / absence, size, and shape of the detected object can be detected more accurately.
[0068]
Moreover, since the right-angled triangular prism 15 and the right-angled triangular light-emitting circuit board 16 are arranged in the square-shaped casing 11 of the light-emitting unit 10 so as to face each other on the oblique side, the space in the casing 11 is reduced. Used effectively. Thus, the size of the light projecting unit 10 can be reduced. Similarly, since the right-angled triangular prism 25 and the right-angled triangular light-emitting circuit board 26 are arranged inside the square-shaped casing 21 of the light receiving section 20 so as to face each other on the oblique side, the space in the casing 21 is reduced. Used effectively. Thus, the size of the light receiving unit 20 can be reduced.
[0069]
Furthermore, since the prisms 15 and 25 are simple in shape and easy to process, they can be manufactured at low cost. Therefore, the cost of the optical detector can be reduced.
[0070]
FIG. 5 is a plan view showing the internal structure of an optical detector according to another embodiment of the present invention. The optical detector in FIG. 5 is a head-separated optical detector. In FIG. 5, illustration of the light receiving unit is omitted.
[0071]
The optical detector of FIG. 5 includes a light projection head 10a and a main body 10b. The light projecting head unit 10a differs from the light projecting unit 10 of FIGS. 1 and 2 in that the light emitting element 13 and the light projecting circuit board 16 are not included in the casing 11a.
[0072]
On the other hand, the main body 10b includes a light emitting element 13, a lens 17, and a light emitting circuit board 16 in a casing 11b. The lens 17 is arranged in front of the light emitting surface of the light emitting element 13.
[0073]
The light projection head 10a and the main body 10b are connected by an optical fiber 18. The light generated from the light emitting element 13 is condensed by the lens 17 of the main body 10b and transmitted to the light projecting head 10a through the optical fiber 18. The light emitted from the tip of the optical fiber 18 in the light projecting head 10 a is converted into parallel light by the lens 13 and emitted to the incident surface 151 of the prism 15. Light incident on the incident surface 151 of the prism 15 is refracted by the incident surface 151, passes through the exit surface 152, and exits from the light projecting window 12.
[0074]
The light receiving section may not include the light receiving element and the light receiving circuit board, the main body 10b may include the light receiving element, the lens, and the light receiving circuit board, and the light receiving section and the main body 10b may be connected by an optical fiber.
[0075]
The configuration of the other parts of the optical detector of the present embodiment is the same as the configuration of the optical detector of FIGS.
[0076]
In the optical detector according to the present embodiment, light having a uniform, high intensity distribution and a wide width is projected from the light projecting head unit 10a to a detection area. Therefore, it is possible to more accurately detect the presence / absence, size, shape, and the like of the detected object.
[0077]
Further, since the prism 15 has a simple shape and is easy to process, it can be manufactured at low cost. Therefore, the cost of the optical detector can be reduced.
[0078]
FIG. 6 is a plan view showing an internal structure of an optical detector according to still another embodiment of the present invention. FIG. 7 is a diagram showing a light path in the optical detector of FIG. In FIG. 6, illustration of the light receiving unit is omitted.
[0079]
In FIG. 6, the light projecting unit 10c includes a substantially rectangular casing 11c. A light projecting window 12 is formed on one side surface of the casing 11c. The casing 11c contains a light emitting element 13, which is a laser diode, a lens 14, a prism 15a, and a light emitting circuit board (not shown).
[0080]
The light emitting element 13 is disposed at one corner in the casing 11 so that the optical axis is substantially along the diagonal direction of the casing 11. The lens 14 is arranged in front of the light emitting surface of the light emitting element 13.
[0081]
One side of the prism 15a becomes the first surface 151a, and the other side becomes the second surface 151b. The prism 15a is disposed in the casing 11c such that the first surface 151a faces the light emitting window 12. The reflection mirror 19 is provided on the second surface 151b.
[0082]
The configuration of the other parts of the optical detector of the present embodiment is the same as the configuration of the optical detector of FIGS.
[0083]
The light emitted from the light emitting element 13 in the light projecting unit 10c is converted into parallel light by the lens 14, enters the first surface 151a of the prism 15a, and is refracted by the incident surface 151a, as shown in FIG. , Into the second surface 151b. The light incident on the second surface 151b is reflected by the reflection mirror 19, passes through the first surface 151a, and is emitted from the light projecting window 12 to the detection area.
[0084]
Also in the optical detector of the present embodiment, light having a uniform, high intensity distribution and a wide width is projected from the light projecting unit 10c to the detection area. Therefore, information such as the presence / absence, size, and shape of the detected object can be detected more accurately.
[0085]
Further, the light refracted by the first surface 151a is reflected by the reflection mirror 19 provided on the second surface 151b and emitted from the first surface 151a, so that the first surface 151a of the prism 15a and the second surface 151a Can be made smaller with the surface 151b. Thus, the size of the prism 15a can be further reduced. As a result, the size of the optical detector can be further reduced.
[0086]
In the optical detector according to the above-described embodiment, the light emitting element 13 is not limited to a laser diode, and another light emitting element such as an LED (light emitting diode) can be used.
[0087]
Further, a prism 25 similar to the prism 15 of the light projecting unit 10 is used in the light receiving unit 20, but the prism 25 is not provided in the light receiving unit 20, and instead of the light receiving element 23, a CCD (charge coupled device) image sensor May be provided.
[0088]
Note that the present invention is not limited to a transmission type optical detector that projects light on an object to be detected and receives information of the transmitted light to detect information about the object to be detected. The present invention can be similarly applied to a reflection type optical detector that detects information on an object to be detected by receiving the reflected light.
[0089]
Further, the present invention can be applied to various optical detectors such as a photoelectric sensor, an optical scanner, and an optical shape measuring device.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an internal structure of an optical detector according to one embodiment of the present invention.
FIG. 2 is a plan view showing an internal structure of a light projecting unit of the optical detector of FIG.
FIG. 3 is a diagram for explaining the principle of the optical detector of FIG. 1;
FIG. 4 is a diagram for explaining refraction of light.
FIG. 5 is a plan view showing the internal structure of an optical detector according to another embodiment of the present invention.
FIG. 6 is a plan view showing an internal structure of an optical detector according to still another embodiment of the present invention.
FIG. 7 is a diagram showing a light path in the optical detector of FIG. 6;
FIG. 8 is a schematic diagram showing a basic configuration of a conventional transmission type optical detector.
FIG. 9 is a schematic diagram showing an example of a conventional optical detector and a diagram showing the relationship between the position of a light irradiation surface and the light intensity.
FIG. 10 is a schematic view showing another example of a conventional optical detector.
[Explanation of symbols]
10,10c Floodlight unit
10a Floodlight head
10b main body
11, 21, 11a, 11b, 11c Casing
12 Floodlight window
13 Light-emitting element
14, 17, 24 lenses
15, 15a, 25 prism
16 Light emitting circuit board
19 Reflection mirror
22 Light receiving window
23 Light receiving element
26 Light receiving circuit board
30 light
151,252 entrance surface
152, 251 Outgoing surface
151a First surface
151b second surface

Claims (9)

An optical detector that projects light onto a detection area and detects information about an object to be detected based on feedback light from the detection area,
A light source for generating light,
A light projection prism that refracts light generated by the light source and projects the light on a detection area,
The light projecting prism,
A first surface on which light generated by the light source is incident at an incident angle of less than 90 degrees;
An optical detector having a predetermined angle with respect to the first surface, and a second surface that emits light refracted by the first surface. The light generated by the light source and the first surface of the light projecting prism are arranged such that the light refracted on the first surface of the light projecting prism is perpendicularly incident on the second surface. The optical detector according to claim 1, wherein an angle between the first surface and the first surface and the second surface of the light projecting prism are set. An optical detector that projects light onto a detection area and detects information about an object to be detected based on feedback light from the detection area,
A light source for generating light,
A light projection prism that refracts light generated by the light source and projects the light on a detection area,
The light projecting prism,
A first surface on which light generated by the light source is incident at an incident angle of less than 90 degrees;
Forming a predetermined angle with respect to the first surface, and a second surface on which light refracted by the first surface is incident;
An optical detection method, wherein a reflection surface for reflecting light incident on the second surface is provided on the second surface, and light reflected on the reflection surface is emitted from the first surface. vessel. The angle between the light generated by the light source and the first surface of the light projecting prism and the light, so that the light reflected by the reflection surface is incident perpendicularly to the first surface. The optical detector according to claim 3, wherein an angle between the first surface and the second surface of the light projecting prism is set. The optical member according to any one of claims 1 to 4, further comprising an optical member that converts light generated by the light source into parallel light and causes the light to enter the first surface of the light projecting prism. Optical detector. The light projecting prism has a substantially triangular shape with the first surface as an oblique side,
A light emitting circuit substrate having a substantially triangular shape having a hypotenuse and provided with a light emitting circuit for driving the light source;
A light-emitting casing that houses the light-projecting prism and the light-emitting circuit board;
The optical system according to any one of claims 1 to 5, wherein the light projecting prism and the light projecting circuit board are arranged in the light projecting casing so as to face each other at an oblique side. Detector. A light-receiving prism that refracts return light based on light projected from the light-projecting prism,
A light receiving element that receives light refracted by the light receiving prism;
The light receiving prism,
A third surface on which the return light is incident,
A fourth surface which forms a predetermined angle with respect to the third surface and refracts light from the third surface and emits the light to the light receiving element. The optical detector according to any one of the above. The light receiving prism has a substantially triangular shape with the fourth surface as an oblique side,
A light receiving circuit substrate having a substantially triangular shape having a hypotenuse and provided with a light receiving circuit for processing a signal output from the light receiving element,
A light-receiving casing that houses the light-receiving prism and the light-receiving circuit substrate,
The optical detector according to claim 7, wherein the light-receiving prism and the light-receiving circuit substrate are arranged in the light-receiving casing so as to face each other at an oblique side. An optical detector that projects light onto a detection area and detects information about an object to be detected based on feedback light from the detection area,
A light source for generating light,
A light projecting prism having a substantially triangular shape and refracting light generated by the light source and projecting the light on a detection region,
A light emitting circuit substrate having a substantially triangular shape and provided with a light emitting circuit for driving the light source;
A casing that houses the light projecting prism and the light projecting circuit board,
The optical detector according to claim 1, wherein the light projecting prism and the light projecting circuit board are disposed in the light projecting casing so as to face each other at an oblique side.

Images