JPH0650214U - Multi-axis photoelectric switch - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the accuracy of the mounting position of the photoelectric device with respect to the body case. [Structure] A front shield plate 19 is provided on the front surface of an element mounting circuit board 13, and a mounting hole 21 is formed therein.
An insulating cap 22 made of resin is attached to the mounting hole 21,
The light receiving element 17 is press-fitted in this state to be in a fixed state, and its lead wire 17a is soldered to the circuit board 13.
The front shield plate 19 is positioned by fitting the positioning protrusions 24 of the main body case 11 into the positioning holes 25 formed here, and is fixed to the main body case 11 by mounting screws 27.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multi-optical axis photoelectric switch in which a plurality of photoelectric elements are mounted on a circuit board arranged in a body case, and more particularly to an improved photoelectric element mounting structure.

[0002]

[Prior art]

 This type of photoelectric switch is used in a state in which the light emitting unit and the light receiving unit are installed separately, and when an object enters between the two units, one of the multiple optical axes between the units is blocked. The switching operation is performed based on

FIG. 5 is a sectional view showing an example of the structure of a conventional light projecting unit. As shown in the figure, a plurality of light projecting elements 3 are mounted on a printed circuit board 2 arranged in a main body case 1 and fixed to the circuit board 2 by soldering. A lens 4 is provided on the front surface of the main body case 1 corresponding to each light projecting element 3, and light is projected from the light projecting element 3 through the lens 4 toward a light receiving element of a light receiving unit (not shown). It The printed circuit board 2 is fixed to the main body case 1 with screws 5 and is positioned by this. A circuit board 6 for constituting a signal processing circuit is attached to the back side of the printed circuit board 2, and a metal shield plate (not shown) for covering these boards 2 and 6 is also provided. ing.

[0004]

[Problems to be solved by the device]

 By the way, it is required that the positioning accuracy of the optical axis in this type of photoelectric switch is considerably high. For example, in the above configuration, if the position of the light projecting element 3 deviates from the normal position by only 0.2 mm, the optical axis angle will deviate by about 1.9 ° when the F value of the lens 4 is 6 mm. Therefore, if the light emitting unit and the light receiving unit are separated by 5 m, the light receiving unit side will appear as a deviation of about 15 cm. In particular, in the recent photoelectric switch, the F value of the lens 4 tends to be small for downsizing, so that the deviation becomes even larger.

In the above-described conventional structure, each light projecting element 3 is positioned in the main body case 1 via the printed circuit board 2. Therefore, the positioning accuracy of each light projecting element 3 is the processing accuracy of the printed circuit board 2 and the main body. It depends on the fixing accuracy for Case 1. However, this type of circuit board is difficult to process with high precision due to its material, and because it simply uses the fixing structure with screws 5, the conventional structure has sufficiently high positioning accuracy for the light projecting element 3. The reality was that they could not do so.

When sufficient positioning accuracy of each photoelectric element cannot be obtained, both units must be arranged close to each other to shorten the detection distance. To avoid such problems, it is necessary to adjust the optical axis after assembly, assemble using a highly accurate jig, measure the positional accuracy, and select only those within the allowable range. However, in both cases, the manufacturing man-hours significantly increase, which causes a cost increase.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a multi-optical axis photoelectric switch capable of improving positioning accuracy of an optical element without incurring cost increase. .

[0008]

[Means for Solving the Problems]

 In the multi-optical axis photoelectric switch of the present invention, a plurality of photoelectric elements are mounted on a circuit board arranged in a main body case, and light is emitted from the photoelectric element or transmitted to the photoelectric element through a light transmitting portion provided in the main body case. In addition, a shield plate, which is placed inside the main body case facing the circuit board, is provided with mounting holes corresponding to the mounting parts of the photoelectric elements. Attach a cylindrical insulating cap to cover the peripheral edge, press-fit each photoelectric element into the insulating cap to fix it to the shield plate, and electrically connect it to the circuit board. One of the features is that the shield plate is fixed to the main body case by providing an engaging portion and an engaged portion for positioning the both on one side and the other side.

[0009]

[Action]

 The photoelectric element is attached to the shield plate via an insulating cap. Since this shield plate is made of metal and can be processed with high precision such as press working, the mounting precision of the photoelectric element on the shield plate is also high. Then, the shield plate is positioned by an engaging portion and an engaged portion provided on the shield plate and the main body case, is attached to the main body case, and is fixed to the main body case with high positional accuracy. Since the shield plate is generally attached to this type of photoelectric switch to prevent noise, it does not cause a cost increase, unlike the case where a special jig or the like is provided.

[0010]

[Effect of device]

 As described above, the multi-optical axis photoelectric switch of the present invention has an excellent effect that the positioning accuracy of the optical element can be improved without increasing the cost.

[0011]

【Example】

 An embodiment in which the present invention is applied to, for example, a photoelectric switch having eight optical axes will be described with reference to FIGS. 1 to 4. The main body case 11 is in the shape of a long rectangular tube, and eight lenses 12 corresponding to a light transmitting portion, for example, eight lenses 12, are attached to the front plate portion 11a. Inside the body case 11, an element mounting circuit board 13 and a processing circuit board 14 located on the back side (right side in FIG. 1) are arranged, and a flexible printed circuit board (see FIG. (Not shown) and the jumper member 16 for electrical connection. Eight light receiving elements 17, which are photoelectric elements, are fixed by soldering to the element mounting circuit board 13 corresponding to each of the eight lenses 12, and the processing circuit board 14 receives signals from the light receiving elements 17. A processing circuit is provided to perform switching operation by performing electrical processing. A cable 18 is connected to the processing circuit board 14 for supplying power to the processing circuit and outputting a switching signal, and the cable 18 is led out from the main body case 11 to the outside.

A front shield plate 19 and a rear shield plate 20 are provided in the main body case 11 so as to cover both the circuit boards 13 and 14 from the front and back. Each shield plate 19 and 20 has a shallow container shape, the rear shield plate 20 is located on the rear side of the processing circuit board 14, and the front shield plate 19 is in front of and opposite to the element mounting circuit board 13. It is located. Of these, the front shield plate 19 has its peripheral wall portion 19a engaged with and connected to the element mounting circuit board 13 as shown in FIG. 2, and at a position corresponding to the mounting portion of each of the light receiving elements 17. Eight circular mounting holes 21 are formed.

An insulating cap 22 made of a synthetic resin having a slight elasticity such as polypropylene is attached to each of the mounting holes 21. As shown in FIG. 4, the insulating cap 22 is configured such that the tubular portion 22a and the flange portion 22b connected to the tubular portion 22a are integrated with each other, and the flange portion 22b is located on the back side of the front shield plate 19. Further, the inner diameter of the tubular portion 22a is set to be slightly smaller than the outer diameter of the light receiving element 17, and the respective light receiving elements 17 are press-fitted into the tubular portion 22a. Then, a spacer plate 23 having a through hole 23a through which the lead wire 17a of the light receiving element 17 is inserted is arranged between each light receiving element 17 and the element mounting circuit board 13, and each lead wire 17a is attached to the element mounting circuit board. Soldered to 13 lands. The insertion hole of the lead wire 17a formed in the element mounting circuit board 13 is formed slightly larger than the lead wire 17a in order to allow the lead wire 17a to freely move.

On the other hand, as shown in FIG. 3, a positioning projection 24 as an engaging portion is integrally provided on the body case 11 toward the front shield plate 19 side, and at a predetermined position of the front shield plate 19. A positioning hole 25 as an engaged portion is formed in the positioning hole 24, and the positioning protrusion 24 is fitted into the positioning hole 25 to position the both. Further, as shown in the figure, a screw insertion hole 26 is formed in the element mounting circuit board 13, and the circuit board 13 is attached to the main body case 11 by a mounting screw 27 that penetrates the element insertion circuit board 26 and is screwed into the main body case 11. It is fixed to. The screw insertion hole 26 is formed to have a diameter relatively larger than the diameter of the mounting screw 27, and the element mounting circuit board 13 has the positioning hole 25 of the front shield plate 19 and the positioning protrusion 24 of the main body case 11. It is adapted to be fixed to the main body case 11 based on the positioning state. The front shield plate 19 is made of metal, and the mounting hole 21 and the positioning hole 25 are formed by pressing.

Next, a procedure for assembling the above configuration will be described. First, the insulating cap 22 is attached to each mounting hole 21 of the front shield plate 19, and the light receiving element 17 is press-fitted into the cylindrical portion 22a. Since the insulating cap 22 is made of synthetic resin and is slightly elastic, the light receiving element 17 is press-fitted into a predetermined position and is fixed there. Next, the spacer plate 23 is mounted so that the lead wire 17a of each light receiving element 17 penetrates the through hole 23a, and the element mounting circuit board 13 is further mounted. At this time, the circuit board 13 is temporarily held by the front shield plate 19, but its position is determined with reference to the position of each light receiving element 17.

Thereafter, by soldering the lead wire 17a of the light receiving element 17 to the land of the circuit board 13, the circuit board 13 is permanently fixed to the front shield plate 19, and the light receiving element 17 is fixed to the circuit board. It will be in the state electrically connected to 13. Then, the processing circuit board 14 is fixed to the element mounting circuit board 13 by soldering the processing circuit board 14 to the element mounting circuit board 13 via the jumper member 16 or the like.

Therefore, the unitized boards 13 and 14 are inserted into the main body case 11, and the positioning projections 24 of the main body case 11 are inserted into the positioning holes 25 of the front shield plate 19 to position the two. By screwing the mounting screw 27 into the body case 11 in this state, the whole body is fixed to the body case 11.

In this fixed state, the position of each light receiving element 17 with respect to the main body case 11 is determined with reference to the front shield plate 19. That is, each light receiving element 17 is positioned and fixed in each mounting hole 21 of the front shield plate 19 via the insulating cap 22, and further, the front shield plate 19 is engaged by the positioning hole 25 and the positioning protrusion 24. It is positioned and fixed to the body case 11. Therefore, in this configuration, the positioning accuracy of each light receiving element 17 with respect to the main body case 11 depends on the processing accuracy of the front shield plate 19.

However, since the front shield plate 19 is made of metal and can be easily pressed with high precision, the mounting hole 21 and the positioning hole 25 can be formed with extremely high precision. As a result, each light receiving element 17 can be fixed to the main body case 11 with high positioning accuracy. Further, since the insulating cap 22 is attached to the mounting hole 21 formed in the front shield plate 19, it is possible to ensure the insulation between the light receiving element 17 and the front shield plate 19 and prevent noise generation. By using the elasticity of the insulating cap 22, the light receiving element 17 can be attached to the front shield plate 19 without rattling, which is more effective in improving the positioning accuracy.

By the way, the maximum displacement of the light receiving element with respect to the main body case was about 0.2 mm in the past, but according to the configuration of the above embodiment, it can be reduced to about 0.05 mm. As a result, under the condition that the focal length F of the lens is F = 6 mm and the distance between the units is 5 m, it is possible to suppress the optical axis shift of about 15 cm to about 4 cm, which is special. It can be kept within the permissible range without the need for optical axis adjustment and selection of non-defective products.

Further, while the excellent effect can be obtained as described above, in this embodiment, the light receiving element 17 is positioned by using the shield plate 19 which is generally mounted conventionally. Therefore, it can be implemented at low cost without any factor of cost increase.

The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications are possible, for example.

(A) In the above embodiment, when the front shield plate 19 and the main body case 11 are positioned, the positioning hole 25 is formed in the front shield plate 19 and the positioning protrusion 24 is provided on the main body case 11. . However, conversely, a cut-and-raised piece may be formed on the front shield plate 19 and a concave portion may be formed in the main body case to engage with the cut-and-raised piece to position them.

(B) In the above-described embodiment, an example in which the invention is applied to the positioning structure of the light receiving element in the light receiving unit is shown, but the invention is not limited to this, and may be applied to the positioning structure of the light projecting element in the light projecting unit. .

In addition, the present invention is not limited to the 8-optical axis type, and can be widely applied to multi-optical axis photoelectric switches having other optical axis numbers, and various modifications can be made without departing from the scope of the invention. Can be done.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a perspective view of an insulating cap.

FIG. 5 is a sectional view showing a conventional multi-optical axis photoelectric switch.

[Explanation of symbols]

 11 ... Main body case 12 ... Lens (translucent part) 13 ... Element mounting circuit board (circuit board) 17 ... Light receiving element (photoelectric element) 19 ... Front shield plate (shield plate) 21 ... Mounting hole 22 ... Insulation cap 24 ... Positioning Protrusion (engaging part) 25 ... Positioning hole (engaged part) 27 ... Mounting screw

Claims (1)

[Scope of utility model registration request] 1. A plurality of photoelectric elements are mounted on a circuit board arranged in a main body case, and light is projected from the photoelectric element or made incident on the photoelectric element through a light transmitting portion provided in the main body case. The shield plate disposed inside the main body case so as to face the circuit board, a plurality of mounting holes provided in the shield plate corresponding to mounting portions of the photoelectric elements, and the shield plate. A cylindrical insulating cap that is attached to cover the inner peripheral edge of each of the mounting holes, and an engaging portion and an engaged portion that are formed on one or the other of the shield plate and the main body case and that position the both. A multi-optical axis photoelectric switch, wherein each photoelectric element is press-fitted into the insulating cap to be fixed and electrically connected to the circuit board.