JPH088468Y2 - Light leakage prevention structure for photoelectric sensor lens - Google Patents

Description

[Detailed description of the device] [Industrial applications]

According to the present invention, in a photoelectric sensor, a light projecting lens that transmits light from a light projecting element and sends the light to a monitoring space and a light receiving lens that collects light from the monitoring space onto a light receiving element are integrated via a connecting body. The present invention relates to a light leakage prevention structure for a lens for a photoelectric sensor which has been made into a new type.

[Prior art]

Conventionally, by detecting the reflected light of the light sent from the light projecting element to the monitoring space by the light receiving element, the presence or absence of an object in the monitoring space is detected based on the amount of reflected light or the position of the light spot. There is provided a photoelectric sensor. In this type of photoelectric sensor, the light from the light projecting element is sent to the monitoring space through the light projecting lens, and the light from the monitoring space is focused on the light receiving element through the light receiving lens. By the way, as a lens used in such a photoelectric sensor, as shown in FIG.
There is provided a product in which and are integrated via a connecting body 3 (see Japanese Utility Model Application No. 63-166902). This lens is made of a translucent material, and has a crank shape at the intermediate portion of the connecting body 3 in order to prevent the light in the light projecting lens 1 from entering the light receiving lens 2. A bent portion that is bent is formed. That is, the side surfaces of the light projecting lens 1 and the light receiving lens 2 are substantially parallel to each other, and between the light projecting lens 1 and the light receiving lens 2, a pair of vertical pieces which are substantially parallel to the side surfaces of the light projecting lens 1 and the light receiving lens 2. 3a, 3b are provided, both vertical pieces 3a,
The lower end of 3b is connected by a horizontal piece 3c, and the upper ends of the vertical pieces 3a, 3b and the light projecting lens 1 and the light receiving lens 2 are connected by horizontal pieces 3d, 3e, respectively. Of. Further, the horizontal piece 3d is connected to the light projecting lens 1 at a position far from the light projecting element 4, and the horizontal piece 3e is connected to the light receiving lens 1.
Is connected at a position far from the light receiving element 5. Therefore, the light from the light projecting element 4 is less likely to enter the connecting body 3, and the light from the connecting body 3 is less likely to enter the light receiving element 5, and a bent portion is formed in the connecting body 3. In addition to the above, the light in the light projecting lens 1 hardly enters the light receiving element 5.

[Problems to be solved by the device]

In the above-mentioned configuration, as compared with the case where no bent portion is formed in the connecting body 3, the light sneak from the light projecting element 4 to the light receiving element 5 can be reduced and the S / N ratio is improved. However, as shown in FIG. 6, a part of the light from the light projecting element 4 is directly incident on the light receiving element 5, is reflected by the lens and is incident on the light receiving element 5, or is transmitted through the connecting body 5. 5 is incident on the light receiving lens 2 and, as shown in FIG. 5, the light that has once exited the space from the connecting body 3 and returned to the connecting body 3 enters the light receiving lens 2, so that the connecting body 3 is bent. The unnecessary light cannot be sufficiently removed only by forming the portion. If there is such unnecessary light, a noise component due to the unnecessary light always enters the light receiving element 5, so that the level difference between the signal light to be detected and the noise becomes small. That is, there is a problem that the S / N ratio is lowered, the detection sensitivity is lowered, and a malfunction occurs. The present invention is intended to solve the above problems,
An object of the present invention is to provide a light leakage prevention structure for a photoelectric sensor lens, which prevents unwanted light from entering a light receiving element, allows a large level difference between signal light and noise, and prevents malfunction.

[Means for Solving the Problems]

In the structure of claim 1, in order to achieve the above object, a light projecting lens that transmits the light from the light projecting element and sends it to the monitoring space, and a light receiving lens that collects the light from the monitoring space on the light receiving element. In a lens for a photoelectric sensor, which is integrally connected via a connecting body, the connecting body is formed in a shape having a bent portion at an intermediate portion, and the connecting body is formed between the light emitting lens and the light receiving lens and between the light emitting element and the light receiving element. The light blocking body for blocking the light from the light projecting element is disposed in the area up to. According to the second aspect of the invention, the light projecting element and the light receiving element are surface-mounted on the circuit board, and the light shield is made of an elastic material that elastically contacts the circuit board. According to the third aspect of the present invention, the lens cover is disposed in front of the portion that straddles the light projecting lens and the light receiving lens, and the light-shielding member is provided with the rib whose tip end surface abuts against the lens cover.

[Action]

According to the configuration of claim 1, in addition to providing the bent portion in the connecting body, the light projecting element is provided in a portion from between the light projecting lens and the light receiving lens to between the light projecting element and the light receiving element. Since a light shield is provided to block the light of the above, the light from the light projecting element is blocked by the light shield and does not enter the light receiving lens or light receiving element. The noise can be significantly reduced.
That is, the S / N ratio of the photoelectric sensor is improved, and malfunction can be prevented. According to the configuration of claim 2, since a part of the light shield is elastically contacted with the circuit board on which the light projecting element and the light receiving element are surface-mounted, the light projecting body is provided on the circuit board regardless of the unevenness of the surface of the circuit board. They can be brought into close contact with each other, and the light can be reliably shielded between the light projecting element and the light receiving element. As a result, S /
The N ratio will be further improved. According to the third aspect of the invention, the lens cover is arranged in front of the portion straddling the light projecting lens and the light receiving lens, and the light-shielding body is provided with the rib whose tip end surface abuts against the lens cover. , It is possible to prevent the light sent from the light emitting lens from being reflected by the lens cover and entering the light receiving lens.
Further improvement of the N ratio can be expected.

【Example】

As shown in FIG. 1, the light projecting lens 1 and the light receiving lens 2 are formed of a translucent material in a shape in which they are integrally coupled via a connecting body 3. The light projecting lens 1 includes an entrance lens section and an exit lens section whose optical axes are orthogonal to each other, and a reflecting surface inclined by about 45 degrees with respect to the optical axes of the entrance lens section and the exit lens section. When the light from the light projecting element 4 is introduced into the light projecting lens 1 through the incident lens section, it is reflected by the reflecting surface and redirected, and then sent out from the emitting lens section and sent to the monitoring space. . On the other hand, the light receiving lens 2 includes an entrance lens portion and an exit lens, and a reflection surface inclined by about 45 degrees with respect to the optical axes of the entrance lens portion and the exit lens portion, like the light projection lens 1. In the light receiving lens 2, the light from the monitoring space is introduced from the incident lens portion, is reflected by the reflecting surface and is redirected, and then is emitted from the emission lens portion and incident on the light receiving element 5. Here, the light projecting lens 1 and the light receiving lens 2 are formed such that their side surfaces are substantially parallel to each other. Similar to the conventional structure, the connecting body 3 has a bent portion bent in a crank shape at an intermediate portion. That is, the connected body 3
Between the light projecting lens 1 and the light receiving lens 2
And a pair of vertical pieces 3a, 3b arranged substantially parallel to the side surface of the light-receiving lens 2 and a horizontal piece 3c connecting the lower ends of the vertical pieces 3a, 3b.
And the horizontal pieces 3d and 3e connecting the upper ends of the vertical pieces 3a and 3b to the light projecting lens 1 and the light receiving lens 2, respectively, are integrated. Therefore, the projection lens 1 and the vertical piece
Gaps are formed between the light receiving lens 2 and the vertical piece 3b, between the vertical piece 3a and the vertical piece 3a, and between the vertical pieces 3a and 3b. The horizontal piece 3d is connected to a position (upper end in FIG. 1) farther from the light projecting element 4 in the light projecting lens 1, and the horizontal piece 3e is far from the light receiving element 5 in the light receiving lens 1 (upper end in FIG. 1). Part). The light projecting element 4 is composed of a light emitting diode, a semiconductor laser or the like, transmits visible light and infrared rays, and is surface-mounted on the circuit board 6 made of a printed board. Also,
The circuit board 6 includes a photodiode, a phototransistor,
The light receiving element 5 made of PSD or the like is surface-mounted. The light projecting element 4 and the light receiving element 5 are arranged so as to face the entrance lens portion of the light projecting lens 1 and the exit lens portion of the light receiving lens 2, respectively. However, the light projecting direction of the light projecting element 4 and the light receiving direction of the light receiving element 5 are substantially orthogonal to the surface of the circuit board 6, and the center line of the monitoring space is substantially parallel to the surface of the circuit board 6. is there. By the way, a light-shielding body 7 is provided at a portion corresponding to the connecting body 3, as shown in FIG. As shown in FIG. 1, the light shield 7 includes a first light shield 7a formed in a tubular shape into which both vertical pieces 3a and 3b are inserted, and a second light shield 7b inserted between both vertical pieces 3a and 3b. It is composed of a light shield 7b. The first light shield 7a is formed in such a shape as to be in contact with the surface of the circuit board 6, whereby light is prevented from wrapping between the light projecting element 4 and the light receiving element 5. The first light blocking member 7a is provided with a light blocking rib 7c projecting in the optical axis direction of the exit lens portion of the light projecting lens 1. As shown in FIG. The lens cover 8 is provided so as to straddle the lens 1 and the light receiving lens 2. Therefore, the light emitted from the light projecting lens 1 is prevented from being reflected by the lens cover 8 and entering the light receiving lens 2. Here, if the first light shield 7a is formed of an elastic material such as rubber, as shown in FIG. 4, even if the first light shield 7a has irregularities due to the wiring pattern 9 on the circuit board 6, the first light shield 7a is Board 6
It is possible to bring the light-emitting element 4 and the light-receiving element 5 into close contact with each other, and to more reliably shield light between the light-projecting element 4 and the light-receiving element 5. Positioning of the light shield 7 with respect to the circuit board 6 is performed by inserting a protrusion provided on the light shield 7 into a positioning hole 10 or a positioning notch 11 formed at an appropriate position of the circuit board 6. As described above, the light shield 7 is inserted between the light projecting lens 1 and the light receiving lens 2 and the vertical pieces 3a, 3b, and in the gaps formed between the vertical pieces 3a, 3b. Reference numeral 7 is arranged so as not to contact the light projecting lens 1, the light receiving lens, and the vertical pieces 3a and 3b. That is, when the ambient temperature changes, the distance between the optical axes of the light projecting lens 1 and the light receiving lens 2 changes, but since the light shield 7 is not in contact with the lens, the light shield 7 The position change of the optical axis due to expansion and contraction can be prevented. Further, if the light shield 7 is made of a soft material, it is possible to suppress the change of the optical axis due to the expansion and contraction of the light shield 7 even when the light shield 7 contacts the lens. By providing the light shield 7 as described above, a light emitting diode which can obtain an output of 10 mW at 50 mA is used as the light emitting element 4.
When driven at 750 mA, the noise level at the light receiving element could be suppressed to 1 to 2 nA. Also, set the ambient temperature to −3
The position detection error is 3 when changing in the range of 0-70 ℃.
% Or less.

[Effect of device]

As described above, in the structure according to claim 1, in addition to providing the bent portion in the connecting body, the projection is provided in a portion from between the light projecting lens and the light receiving lens to between the light projecting element and the light receiving element. Since a light shield for blocking the light from the optical element is provided, the light from the light projecting element is blocked by the light shield and does not enter the light receiving lens or the light receiving element. It has an advantage that noise can be reduced significantly compared to. That is, the S / N ratio of the photoelectric sensor is improved, and it is possible to prevent malfunction. According to the structure of claim 2, since a part of the light shield is elastically contacted with the circuit board on which the light projecting element and the light receiving element are mounted, the light shield is closely attached to the circuit board regardless of the unevenness of the surface of the circuit board. Therefore, it is possible to surely shield the space between the light projecting element and the light receiving element. As a result, S /
There is an advantage that the N ratio is further improved. According to the third aspect of the invention, the lens cover is arranged in front of the portion straddling the light projecting lens and the light receiving lens, and the light-shielding body is provided with the rib whose tip end surface abuts against the lens cover. , It is possible to prevent the light sent from the light emitting lens from being reflected by the lens cover and entering the light receiving lens.
There is an advantage that further improvement of the N ratio can be expected.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention, FIG. 2 is a sectional view of an essential part of the same, FIG. 3 is a plan view of the same, FIG. 4 is a sectional view of an essential part of the same, and FIG. FIG. 6 is a front view showing a conventional example, and FIG. 6 is a front view showing problems of the conventional example. 1 ... Emitting lens, 2 ... Receiving lens, 3 ... Concatenated body,
4 ... Projector element, 5 ... Photosensor element, 6 ... Circuit board, 7
…… Shade, 7c …… Shading rib, 8 …… Lens cover.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location G01V 8/10 H01H 35/00 C H03K 17/78 D (56) Reference JP-A-2-21282 (JP, JP, A) JP 61-35575 (JP, A) Actually open 2-87343 (JP, U) Actually open 63-31050 (JP, U) Actually open 54-48365 (JP, U) Actually open 3 -88178 (JP, U)

Claims (3)

[Scope of utility model registration request] 1. A light projecting lens that transmits light from a light projecting element and sends it to a monitoring space, and a light receiving lens that collects light from the monitoring space on a light receiving element are integrally connected via a connecting body. In the structure for preventing light leakage of the photoelectric sensor lens, the connecting body is formed in a shape having a bent portion in the intermediate portion, and is provided in a portion between the light projecting lens and the light receiving lens and between the light projecting element and the light receiving element. Is a structure for preventing leakage of light from a lens for a photoelectric sensor, which is provided with a light blocking body that blocks light from a light projecting element. 2. The light leakage prevention structure for a photoelectric sensor lens according to claim 1, wherein the light projecting element and the light receiving element are surface-mounted on a circuit board, and the light shielding body is formed of an elastic material elastically contacting the circuit board. . 3. A lens cover is disposed in front of a portion straddling the light projecting lens and the light receiving lens, and a rib whose tip end surface abuts against the lens cover is provided in a protruding manner on the light shielding body. The light leakage prevention structure for a lens for a photoelectric sensor according to claim 1 or 2.