JP4178019B2 - Multi-axis photoelectric sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-optical axis photoelectric sensor.
[0002]
[Prior art]
A multi-optical axis photoelectric sensor is known as a type of transmissive photoelectric sensor. Referring to FIG. 1, a multi-optical axis photoelectric sensor 1 includes a projector 2 and a light receiver 3 that are arranged to face each other. Both the projector 2 and the light receiver 3 have a plurality of photoelectric elements, that is, a light projecting element or a light receiving element, arranged in a line at equal intervals, and are emitted from the light projector 2 toward the light receiver 3. When a light curtain is formed by the light beam 4 and at least a part of the light curtain is shielded, a light shielding object detection signal is output. This type of multi-optical axis photoelectric sensor 1 is disposed, for example, around mechanical equipment as a means for ensuring the safety of workers.
[0003]
The density of the light curtain formed by the multi-optical axis photoelectric sensor 1, that is, the detection capability of the multi-optical axis photoelectric sensor 1 is expressed by the diameter D of the minimum detection body 5. The minimum detection body 5 is composed of a cylindrical opaque body. When the minimum detection body 5 is moved in the arrangement direction of the light beams 4 and the light curtain is cut vertically, the light beam 4 having at least one optical axis is completely shielded. The diameter D of the minimum detection body 4 that can be made is the detection capability of the multi-optical axis photoelectric sensor 1.
[0004]
That is, referring to FIG. 2, when an opaque cylindrical body (minimum detection body 5) is inserted into a light curtain formed by the multi-optical axis photoelectric sensor 1, the opaque cylindrical body always emits a light beam 4 having at least one optical axis. That the light is completely shielded means that the minimum detector 5 has a diameter D that completely shields the light beam 4 having two optical axes. Therefore, when the light beam 4 has a circular cross section, the diameter of the light beam 4 is represented by “d”, and the central axis of the light beam 4, that is, the distance between the optical axes (distance between the optical axes) is “p”. , The diameter D of the minimum detection body 5 can be expressed by the following equation.
[0005]
D (diameter of minimum detection object) = p (distance between optical axes) + d (diameter of light beam)
[0006]
By the way, various proposals have been made and implemented regarding the multi-optical axis photoelectric sensor.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-255614
Japanese Patent Laid-Open No. 10-255614 discloses that the lens 7 of the projector and the light receiver is formed in an elliptical shape as shown in FIG. 3 in order to make the distance between the optical axes as small as possible. Further, this publication discloses a unit lens unit in which a lens is incorporated in each of a plurality of openings of a lens holder (see FIGS. 6 and 8 of the publication).
[0009]
[Patent Document 2]
JP 2001-135208 JP
Japanese Patent Laid-Open No. 2001-135208 discloses an optical system unit in which a plurality of optical system parts each including a photoelectric element, a lens arranged opposite to the photoelectric element, and a member forming an optical path between these parts are arranged. It is disclosed that a single light projector and light receiver are made by incorporating a plurality of optical system units.
[0011]
[Patent Document 3]
Japanese Patent Laid-Open No. 10-74432
Japanese Patent Laid-Open No. 10-74432 discloses an optical system unit in which a plurality of optical system parts are arranged in the same manner as the above-mentioned Japanese Patent Laid-Open No. 2001-135208. It is disclosed that a plurality of lenses included in one optical system unit are integrally molded so that “a lens formed integrally with the cover member 37” is included in the paragraph.
[0013]
[Problems to be solved by the invention]
In relation to the manufacture of a multi-optical axis photoelectric sensor, for example, when a plurality of lenses are integrally molded as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-74432, an error in the distance between lenses, that is, the distance between optical axes, Variation is the main cause, and the degree of error is on the order of 0.1 mm.
[0014]
On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 10-255614, when incorporating individually manufactured lenses, the variation at the time of incorporation is added to the variation generated at the time of manufacturing the lens. The error of the distance between the optical axes, that is, the distance between the optical axes is on the order of 1 mm.
[0015]
The same problem is caused when a multi-optical axis photoelectric sensor is manufactured by incorporating a plurality of optical system units as disclosed in the above-mentioned JP-A-2001-135208 and JP-A-10-74432, or in JP-A-10-74432. This also occurs when a multi-optical axis photoelectric sensor is manufactured by incorporating a plurality of lens plates formed by integrally molding a plurality of lenses as disclosed in the publication.
[0016]
That is, the error of the distance between the optical axes in the unit optical system unit and the unit lens plate is slight, but when a multi-optical axis photoelectric sensor is manufactured by incorporating a plurality of them, the unit optical system unit or the unit lens plate The variation when incorporating is relatively large. Referring to FIG. 4, for example, the lens 10 of the multi-optical axis photoelectric sensor is circular, the diameter of the lens 10 is 5 mm, and the distance between the lenses, that is, the distance between the optical axes is 20 mm. When the lens plate 11 in which the lens 10 is integrally molded is manufactured, the design minimum diameter D, that is, the outermost peripheral separation distance between the adjacent lenses 10 is 25 mm, but the adjacent lens plates 11 and 11 are assembled. If the maximum variation is 1 mm, the diameter D of the minimum detection body, that is, the outermost peripheral separation distance between adjacent lenses 10 is 27 mm.
[0017]
Further, as shown in FIG. 5, when a plurality of multi-optical axis photoelectric sensors 1 and 1 are connected to form an enlarged light curtain, the adjacent multi-optical axis photoelectric sensors 1 and 1 face each other. The same can be said for the light beam located at the end. That is, the light between the optical system components (for example, the lens 10 positioned at the end) located at the end of the multi-optical axis photoelectric sensor 1 when the end faces of the adjacent multi-optical axis photoelectric sensors 1 and 1 are arranged to face each other. When the inter-axis distance p is designed to be the same as the inter-optical axis distance p of the central portion of the multi-optical axis photoelectric sensor 1, variation when assembling the optical system parts positioned at the end of the multi-optical axis photoelectric sensor 1. As a result, the substantial diameter D of the maximum detector is enlarged.
[0018]
Accordingly, an object of the present invention is to substantially increase the diameter of the minimum detection body due to variations in the assembly of the optical system unit when a single multi-optical axis photoelectric sensor is fabricated by assembling a plurality of optical system units. It is an object of the present invention to provide a multi-optical axis photoelectric sensor capable of suppressing the above-described problem.
[0019]
Another object of the present invention is that when a multi-optical axis photoelectric sensor is made by incorporating a plurality of lens plates formed by integrally molding a plurality of lenses, the diameter of the minimum detection body is substantially reduced due to variations in the assembly of the lens plates. An object of the present invention is to provide a multi-optical axis photoelectric sensor capable of suppressing expansion.
[0020]
Another object of the present invention is to form a light curtain expanded by connecting a plurality of multi-optical axis photoelectric sensors, so that the maximum detection body diameter between adjacent multi-optical axis photoelectric sensors is An object of the present invention is to provide a multi-optical axis photoelectric sensor capable of suppressing substantial enlargement due to variations in assembly of optical system components located at the ends.
[0021]
[Means for Solving the Problems]
Such a technical problem, according to the first aspect of the present invention,
A light beam shape of a first substantially circular cross section that is projected or received by an optical system component located at one end of each of a plurality of optical system units built in the multi-optical axis photoelectric sensor, and located at the other end The light beam shape of the second substantially circular cross-section that is projected or received by the optical system component is a multi-light having a cross-sectional shape in which the portions of the first and second light beams facing each other are notched This is accomplished by providing an axial photoelectric sensor.
[0022]
In order to make the cross-sectional shapes of the first and second light beams at both ends of the unit into a shape in which the portions of the first and second light beams facing each other are cut out, as an example, an optical system component is used. For example, a light shielding paint is applied to a part of a circular lens, a light shielding material is provided on a part of a cover member arranged outside the lens, and an inner surface of a lens holder that forms a light guide path between the photoelectric element and the lens. A means for changing the cross-sectional shape of the light beam, such as forming a part of the cross section with a straight line and the remaining part with a circular arc, can be mentioned.
[0023]
According to the second aspect of the present invention,
The cross-sectional shape of the light beam formed by the optical system component integrally formed with a plurality of optical system units included in the multi-optical axis photoelectric sensor is changed to the first optical system component located at one end of each unit and the other The light-shielding means provided at the portion facing the second optical system component located at the end has a shape in which the cross-sectional shapes of the light beams of the first and second optical system components are cut out from each other. The above-mentioned technical problem is achieved by providing a multi-optical axis photoelectric sensor characterized by the above.
[0025]
According to the third aspect of the present invention, the technical problem is
A multi-optical axis photoelectric sensor incorporating a plurality of lens plates formed by integrally molding a plurality of lenses, and having a shape in which one lens located at both ends of the lens plate and the other lens are cut away from each other. This is accomplished by providing a featured multi-optical axis photoelectric sensor.
[0026]
According to a fourth aspect of the present invention, the technical problem is
A cross-sectional shape of the first and second light beams formed by the first and second optical system parts located at both ends of the multi-optical axis photoelectric sensor is a third shape formed by the optical system part located at the center. compared to the cross-sectional shape of the light beam is achieved by providing a multi-optical axis photoelectric sensor characterized by having a first, shape cut out facing each other part of the second light beam.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. The embodiment shown here relates to a lens plate formed by integrally molding a plurality of lenses, but this is merely an example that embodies the present invention regarding the cross-sectional shape of a light beam of a multi-optical axis photoelectric sensor. Not too much. In addition, the shape of each lens included in the lens plate substantially forms the cross-sectional shape of the light beam. Therefore, the description of the shape of the lens substantially explains the cross-sectional shape of the light beam. I want to be understood.
[0028]
FIG. 6 is a front view of the multi-optical axis photoelectric sensor. The multi-optical axis photoelectric sensor 100 includes first to third three optical system units 101 to 103. These units 101 to 103 are arranged in addition to the light projecting element or the light receiving element. It includes a substantially cylindrical light guide for guiding related light (referred to as a lens holder in the above-mentioned Japanese Patent Laid-Open No. 10-255614) and the like, and this lens holder is formed integrally with the units 101-103. The In the multi-optical axis photoelectric sensor 100, the unit 101 to 103 and the first to sixth lens plates 105 to 110 are incorporated, so that 24 optical system parts are arranged in a line at regular intervals. Each of the lens plates 105 to 110 is integrally formed with four lenses 111 to 114, respectively.
[0029]
Of the four lenses 111 to 114, the two central lenses 112 and 113 sandwiched between the two lenses 111 and 114 located at both ends have a circular shape. On the other hand, the two end lenses 111 and 114 positioned at the ends have a shape in which the sides facing each other are configured by a straight line 115 orthogonal to the lens arrangement direction axis L and the remaining portion is configured by an arc 116. In other words, the end lenses 111 and 114 have a shape in which a part of the circular contour of the central lenses 112 and 113 is cut out by the straight line 115.
[0030]
According to this, the optical axis distances of the multi-optical axis photoelectric sensor 100 are all equal, but between two adjacent lens plates 105 and 106, between 106 and 107, between 107 and 108, 109, the outermost peripheral separation distance between the end lens 116 and the end lens 111 between 109 and 111, that is, the diameter of the minimum detection body is, for example, the designed outermost peripheral separation distance, ie, the minimum, of the two central lenses 112 and 113. It becomes smaller than the diameter of the detection body by the cutout of a part of the circular shape. Accordingly, by cutting out part of the end lenses 111 and 116, the outermost peripheral separation distance between the end lenses 111 and 116 between adjacent lens plates is reduced, so that the lens plates 105 to 110 are assembled. It becomes possible to absorb the variation in the case.
[0031]
In other words, if the diameter of the minimum detection body of the light curtain formed by the multi-optical axis photoelectric sensor 100 is the same as the diameter of the minimum detection body defined by the two central lenses 112 and 113, the end lens By notching a part of 111, 116, the variation in assembling the lens plates 105-110 can be absorbed by the notch of the end lenses 111, 116.
[0032]
In the above-described preferred embodiment, a lens plate in which four lenses are integrally molded has been described as an example. However, the same applies to a lens plate 200 in which two lenses 201 and 202 are integrally molded as shown in FIG. . In this case, the two lenses 201 and 202 included in the lens plate 200 are end lenses positioned at the ends of the lens plate 200, and the two end lenses 201 and 202 are the same as those in the above-described embodiment. Similarly, the side opposite to each other is configured by a straight line 115 orthogonal to the lens arrangement direction axis L, and the remaining portion is configured by an arc 116.
[0033]
Although the embodiment of the present invention has been described above, as illustrated in FIG. 5, when an enlarged light curtain is formed by connecting a plurality of multi-optical axis photoelectric sensors, it is positioned at both ends of each multi-optical axis photoelectric sensor. The cross-sectional shape of the light beam of the optical system component is a portion where the light beams of the both ends face each other, that is, the inward side portion, compared to the light beam of the substantially circular cross section of the optical system component located at the center of the multi-optical axis photoelectric sensor By making the shape into a notch, the diameter of the minimum detection body between adjacent multi-optical axis photoelectric sensors may be designed to be relatively small.
[0034]
In order to embody the present invention relating to the cross-sectional shape of a light beam, it is integrally formed with a unit that forms an optical path included in an optical system unit as disclosed in, for example, Japanese Patent Laid-Open Nos. 10-74432 and 2001-135208. A cross-sectional shape of the light guide path inside the lens holder to be provided, a shielding member that shields a part of the light guide path, or a shielding member that shields a part of the lens, or a light shielding paint on a part of the lens It may be by means such as coating.
[0035]
FIG. 8 shows four lens holders 300 (also referred to as element holders) formed integrally with the optical system units 101 to 103 (FIG. 6) and a part of the lens plates 107 and 108 (FIG. 6) described above. The combination with the notch end lenses 111 and 114 is illustrated.
[0036]
Each of the four lens holders 300 can hold the light projecting element or the light receiving element 301 in a positioned state. As can be understood from FIG. Sections corresponding to each other are cut by a straight line 303 so that the cross-sectional shape of the peripheral wall of the light guide path 302 of the end holders 300a and 300b located at the ends of the end 103 is substantially the same as the shape of the end lenses 111 and 114. Has a missing shape. Needless to say, a partially cut-out cross-sectional shape of the light beam can be formed by combining the partially cut-out shape of the end lenses 111 and 114 and the partially cut-out cross-sectional shape of the end holders 300a and 300b.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a minimum detection body used in the industry of a multi-optical axis photoelectric sensor.
FIG. 2 is a diagram for explaining a minimum detection body, similar to FIG. 1;
FIG. 3 is a diagram for explaining a lens shape employed in a conventional multi-optical axis photoelectric sensor.
FIG. 4 is a diagram for explaining a variation in the diameter of a minimum detection body accompanying assembly of components of a multi-optical axis photoelectric sensor.
FIG. 5 is a diagram for explaining a variation in the diameter of a minimum detection body between adjacent multi-optical axis photoelectric sensors when a wide light curtain is formed by a plurality of multi-optical axis photoelectric sensors.
FIG. 6 is a diagram for explaining a shape of a lens constituting a lens plate employed in the multi-optical axis photoelectric sensor of the embodiment.
FIG. 7 relates to a lens plate as in FIG. 6, but is a diagram for explaining an embodiment in which two lenses are integrally formed on this lens plate.
FIG. 8 is a diagram for explaining a combination of a partially cut shape of an end lens and a light guide path of a lens holder having a cross-sectional shape corresponding to the end lens.
[Explanation of symbols]
100 Multi-optical axis photoelectric sensors 101 to 103 Optical system units 105 to 110 Lens plates 111 to 114 Lenses 111 and 114 End lens

Claims (5)

A light beam shape of a first substantially circular cross section that is projected or received by an optical system component located at one end of each of a plurality of optical system units built in the multi-optical axis photoelectric sensor, and located at the other end The light beam shape of the second substantially circular cross-section that is projected or received by the optical system component is a multi-light having a cross-sectional shape in which the portions of the first and second light beams facing each other are notched Axis photoelectric sensor. The cross-sectional shape of the light beam formed by the optical system component integrally formed with a plurality of optical system units included in the multi-optical axis photoelectric sensor is changed to the first optical system component located at one end of each unit and the other by the second optical components and shielding means provided on the portion facing each other of which is located on the edge, these first, a shape that the cross-sectional shape of the light beam of the second optical system parts cut away face each other part A multi-optical axis photoelectric sensor comprising: A multi-optical axis photoelectric sensor incorporating a plurality of lens plates formed by integrally molding a plurality of lenses, and having a shape in which one lens located at both ends of the lens plate and the other lens are cut away from each other. A multi-optical axis photoelectric sensor. The shape of one lens and the other lens located at both ends of the lens plate has a shape in which a portion of these lenses facing each other is a straight line orthogonal to the lens arrangement axis and the other portion is an arc. The multi-optical axis photoelectric sensor according to 1. A cross-sectional shape of the first and second light beams formed by the first and second optical system parts located at both ends of the multi-optical axis photoelectric sensor is a third shape formed by the optical system part located at the center. A multi-optical axis photoelectric sensor characterized by having a shape in which portions of the first and second light beams facing each other are cut out as compared to a cross-sectional shape of the light beam.

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