JPH0572027U - Photoelectric sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] The filter plate can be fixed at an appropriate angle to improve the optical performance. [Structure] The filter plate 13 is housed in the step portion 15,
It is pressed and fixed by a pressing projection 20 provided on the inner peripheral edge of the step portion 15 and melted and broken by the ultrasonic welding device. The front cover 1 so as to cover the filter plate 13.
4 is attached. The filter plate 13 has a front cover 14
Since the filter plate 13 is fixed by the pressing protrusion 20 before mounting, the filter plate 13 is prevented from being displaced or pinched between the unit case and the front cover, resulting in an inappropriate mounting state.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a photoelectric sensor provided with a filter plate between a unit case and a front cover, and more particularly to an improved photoelectric filter fixing structure.

[0002]

[Prior Art]

 An example of this type of photoelectric sensor is a retroreflective photoelectric sensor. This is because the light emitting element and the light receiving element are arranged in the same case so that they face the same direction, and a polarization filter with a polarization direction different by 90 degrees is provided in the optical path of the light entering and exiting each photoelectric element. It has a different structure. For example, as shown in FIG. 11, this type of sensor is set such that the main body 1 is sandwiched between the reflection mirror 2 and the passage through which the body 3 to be detected such as a glass bottle passes.

Therefore, when the detected body 3 does not exist, the light projected from the light projecting element of the main body 1 is reflected by the reflection mirror 2 and enters the light receiving element of the main body 1, and the detected body 3 is When present, the light projected from the light projecting element is reflected by the detected body 3 and enters the light receiving element.

By the way, when the light is reflected by the reflection mirror 2, the vibration direction of the light is rotated by 90 degrees, and when the light is reflected by a mirror surface object such as glass, the vibration direction of the reflected light changes. do not do. The retroreflective photoelectric sensor is designed to detect the object 3 to be detected by utilizing this property, and therefore two polarizing filters are provided as described above.

That is, since the polarization filter is provided in front of the light projecting element, only the light of the vibration component in the lateral direction of the light from the light projecting element is projected forward. On the other hand, since a polarizing filter with a polarization direction different from the polarizing filter on the light emitting side by 90 degrees is also provided in front of the light receiving element, light reflected by a mirror-like object that does not have the property of rotating the vibration direction is It cannot pass through the polarizing filter. However, the light reflected by the reflection mirror 2 having the property of rotating the oscillation direction of the light by 90 degrees comes to coincide with the direction of the polarization filter on the light receiving side, and passes through here to reach the light receiving element. It becomes like this. Thus, the light reflected by the reflection mirror 2 and the light reflected by the detected body 3 can be distinguished from each other.

Since the object 3 to be detected is detected according to such a principle, it is ideal that the polarization filters are attached so that the polarization directions thereof are exactly 90 ° relative to each other.

Therefore, in the conventional retroreflective photoelectric sensor, as shown in FIG. 12, a step 6 for accommodating the rectangular polarization filter 5 is formed on the front surface of the unit case 4, and the polarization filter is provided in the step 6. The front cover 7 is fixed to the unit case 4 by, for example, ultrasonic welding in a state in which 5 is accommodated.

[0008]

[Problems to be solved by the device]

 However, in the above structure, it is necessary to provide a certain clearance between the step portion 6 and the polarization filter 5 in consideration of the workability of housing the polarization filter 5, so that the polarization filter 5 is accommodated in the step portion 6. The polarization filter 5 is free to move. Therefore, as shown in FIG. 14, the two polarizing filters 5 may both be tilted in the opposite directions. In this case, the relative angle of the polarizing directions of the respective filters 5 is 90 degrees. Since it does not correspond to the degree, it becomes difficult to distinguish the reflection from the detection object 3 and the reflection from the reflection mirror 2 depending on the vibration direction of the reflected light. This means that it becomes impossible to detect a specular object, which is a feature of the retroreflective photoelectric sensor, and the sensor must be treated as a defective product.

Further, in the above configuration, since the front cover 7 is attached and fixed until the polarization filter 5 can freely move in the step portion 6, when the front cover 7 is attached, for example, as shown in FIG. The polarizing filter 5 may be displaced and fixed as it is sandwiched between the front cover 7 and the unit case 4. In this case, light that does not pass through the polarization filter 5 is projected forward, which is also a defective product.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a photoelectric sensor capable of fixing a filter plate in an appropriate state and ensuring stable quality.

[0011]

[Means for Solving the Problems]

 The photoelectric sensor of the present invention comprises a unit case to which a photoelectric element and a lens are attached, a front cover attached to the unit case, and a filter plate provided between the unit case and the front cover. The unit case has a stepped portion for accommodating the filter plate, and the inner peripheral edge of the stepped portion is pressed and fixed by being melted by an ultrasonic welding device. The feature is that the pressing protrusion is provided.

[0012]

[Action]

 The filter plate is not only housed in the stepped portion, but also is held and fixed by the holding projections provided on the inner peripheral edge of the stepped portion and melted and broken by the ultrasonic welding device. For this reason, the filter plate does not move out of the way, and does not tilt and become improperly attached. Further, even when the front cover is attached to the unit case, the filter plate is prevented from shifting, so that the filter plate is not sandwiched between the unit case and the front cover and is not in an inappropriate attachment state.

[0013]

[Effect of the device]

 As described above, according to the configuration of the present invention, it is possible to prevent the mounting state from becoming improper due to the displacement movement of the filter, and thus it is possible to obtain a high-quality photoelectric sensor.

[0014]

【Example】

 An embodiment in which the present invention is applied to a retroreflective photoelectric switch will be described with reference to FIGS. 1 and 10.

FIG. 1 is an exploded view before assembling the photoelectric switch of this embodiment. Here, the unit case 11 is made of black plastic and has an element housing recess 11a for housing two photoelectric elements, that is, a light emitting element and a light receiving element (both not shown) on the back side. A lens housing portion 11c is continuously formed from here through a cavity portion 11b which is tapered toward the front side.

Each lens housing portion 11c of the unit case 11 has a rectangular shape when viewed from the front, and a plastic lens 12 is press-fitted therein and fitted into the element housing recess 11a as shown in FIG. A unit on the photoelectric element side (not shown) is fitted. The front surface of each lens 12 has a flat surface shape, and rectangular polarization filters 13 as filter plates, which will be described in detail later, are stacked on top of each other, and further covered by a front cover 14 made of plastic. Is fixedly attached to the unit case 11.

Now, each lens housing portion 11c of the unit case 11 is opened toward the front surface, and a step portion 15 is formed at the peripheral edge portion of each opening. The overall shape of the step portion 15 is a rectangular shape whose vertical and horizontal dimensions are slightly different from each other, and is formed in an angular relationship in which they are rotated by 90 degrees. Also, for example, the stepped portion 15 on the light receiving side (right side in FIG. 2) is a triangular corner portion 15a in which two corners, the upper left corner and the upper right corner, are triangularly angled when viewed from the front, and the lower left corner and The two corners at the lower right are cut corners 15b that have not entered the square. Further, the step portion 15 on the light projecting side (the left side in FIG. 2) is a triangular corner portion 15a in which two corners, the upper left corner and the lower left corner, are triangle-shaped when viewed from the front, and the upper right corner and the upper right corner. The two corners at the lower right are cut corners 15b that have not entered the square.

Of the inner peripheral edge of the step 15, the partition wall 16 located at the center of the unit case 11 is provided with two welding projections 17 integrally projecting upward in FIG. 1. As shown enlarged in FIG. 4, both right and left side surfaces are in the shape of a rectangle that rises at a right angle to the front surface of the unit case 11.

Further, in the inner peripheral edge of the step portion 15, two welding projections 18 are also integrally provided so as to project upward at portions located on both left and right sides of the unit case 11 in FIG. There is. As shown in the enlarged view of FIG. 4, the inner portion of the stepped portion 15 rises at a right angle to the front surface of the unit case 11, and the inclined portion 18a is formed on the outer portion.

On the other hand, the polarization filter 13 is a rectangle whose vertical and horizontal dimensions are slightly different, and two adjacent corners thereof are cut into triangular shapes corresponding to the triangular corners 15 a of the step portion 15, The remaining two corners have a shape cut out in a square shape corresponding to the cut corner 15b of the step 15.

Next, a procedure for assembling the photoelectric switch of this embodiment will be described. First, the lenses 12 are housed in the respective lens housings 11c of the unit case 11, and the polarization filters 13 are placed on each of the lenses 12 (see FIG. 4). At this time, the two step portions 15 of the unit case 11 and the polarization filter 13 have different vertical and horizontal dimensions, and each corner has a different shape. Can only be set in. That is, as shown in FIG. 2, in the step portion 15 on the light receiving side (right side) of the unit case 11, the triangular corner portions 15a are provided at two upper sides, and in the step portion 15 on the light projecting side (left side), the triangular corner portion 15a is provided. 15a are provided at two places on the left side. For this reason, the polarization filter 13 can be set in the step portion 15 only in a direction in which the triangularly cut corners are on the light receiving side, and the triangularly cut corners are on the left side on the light projecting side. It can be set on the step portion 15 only in the direction. Therefore, since the same polarization filter 13 is used, the setting directions of the polarization filters 13 on the light receiving side and the light projecting side are different from each other by 90 degrees. This state is as shown by attaching an arrow indicating the polarization direction to each polarization filter 13 in FIG.

After arranging the two polarizing filters 13 differently by 90 degrees in this way, the unit case 11 is set in an ultrasonic welding device and the polarizing filters 13 are ultrasonically welded. This ultrasonic welding is performed by pressing an ultrasonic horn 19 against the welding protrusions 17 and 18 as shown in FIG. 5, and thereby causing the welding protrusions 17 and 18 to be melted and destroyed by frictional heat generated by ultrasonic vibration. At this time, since the two welding projections 17 protruding from the partition wall 16 of the unit case 11 are in the shape of a rectangular parallelepiped, the ultrasonic horns 19 are blasted so as to spread evenly on both left and right sides. .. However, since the total of four welding projections 18 located on both the left and right sides of the unit case 11 have the inclined surfaces 18a, when the welding projections 18a are destroyed, as shown by the arrow A in FIG. It deforms while falling toward the inner circumference. As a result, the polarization filter 13 is pushed in the direction of arrow B in the figure, and both the left and right polarization filters 13 are brought into contact with the partition 16 of the unit case 11.

When the ultrasonic horn 19 is further pressed, the welding projection 18 is completely melted and becomes the pressing projection 20, which presses and fixes each polarization filter 13 as shown in FIGS. 7 to 9. Come to do.

After that, the front cover 14 is attached to the front surface of the unit case 11, and is further ultrasonically welded and fixed to the unit case 11. Assembling on the unit case 11 side is completed, and a photoelectric conversion device (not shown) is shown. Mount the element unit and complete the photoelectric sensor assembly.

According to the above embodiment, the following effects can be obtained.

(1) Since each polarization filter 13 is pressed and fixed to the unit case 11 by the pressing protrusion 20, it is possible to reliably prevent the displacement movement. Therefore, since the mutual angle of the polarization directions of the both polarization filters 13 can be accurately maintained at an ideal 90 degrees, the optical performance can be maintained at a high level. In particular, when the front cover 14 is attached after the polarization filter 13 is arranged, it is possible to reliably prevent the polarization filter 13 from being displaced and being sandwiched between the unit case 11 and the front cover 14. Therefore, as shown in FIG. 13, it is possible to prevent the situation where the light that does not pass through the polarization filter 13 leaks out, and the generation of defective products is eliminated.

(2) Moreover, in particular, in this embodiment, since the inclined surfaces 18a are formed on the welding projections 18 provided on both the left and right sides of the unit case 11, when the inclined surfaces 18a are broken by the ultrasonic horn 19, as shown in FIG. The polarizing filter 13 is deformed while falling down in the direction indicated by the arrow A, and the polarization filter 13 is pushed in the direction of the arrow B in the figure and abuts against the partition wall portion 16 of the unit case 11. For this reason, the polarization filters 13 are arranged in a straight line with the side surface of the partition wall 16 as a reference, and the mutual angle of the polarization directions of both polarization filters 13 can be set more accurately at 90 degrees, and the optical performance is improved. Further contribute to the improvement of.

(3) Further, particularly in the present embodiment, the shape of the step portion 15 of the unit case 11 and the shape of the polarization filter 13 are different in vertical and horizontal dimensions, and each corner portion is formed in a different shape. Therefore, even if the polarizing filter 13 is to be set in the step portion 15 in the wrong direction, it cannot be fitted in the step portion 15 and can only be fitted in the appropriate direction. Therefore, although the polarizing filter 13 is one type common to both the light receiving and the light projecting, it can be easily used in two types, and the number of parts can be reduced and the assembling work can be efficiently performed. You can The present invention is not only applied to the retroreflective type photoelectric sensor as in the above-described embodiment, but also widely applied to the photoelectric sensor having a configuration in which the filter plate is arranged between the unit case and the front cover. be able to.

[Brief description of drawings]

FIG. 1 is an exploded vertical sectional view before assembly.

FIG. 2 is a front view showing a state in which a lens and a polarization filter are also mounted on the unit case.

FIG. 3 is an exploded perspective view before assembly.

FIG. 4 is an enlarged vertical sectional view showing a state in which a polarization filter is set.

FIG. 5 is a vertical sectional view showing a state of performing ultrasonic welding.

FIG. 6 is a vertical sectional view showing a state in the middle of ultrasonic welding.

FIG. 7 is a vertical sectional view showing a state after ultrasonic welding.

FIG. 8 is a front view of the same.

FIG. 9 is an enlarged vertical sectional view of the same.

FIG. 10 is a vertical cross-sectional view with a front cover attached.

FIG. 11 is a perspective view showing a usage state of a retroreflective photoelectric switch.

FIG. 12 is a vertical sectional view showing a conventional photoelectric switch.

FIG. 13 is a vertical cross-sectional view showing defects in the conventional photoelectric switch.

FIG. 14 is a front view showing defects in the conventional photoelectric switch.

[Explanation of symbols]

 11 ... Unit case 12 ... Lens 13 ... Polarization filter 14 ... Front cover 15 ... Step portion 17, 18 ... Welding projection 19 ... Ultrasonic horn 20 ... Pressing projection

Claims (1)

[Scope of utility model registration request] 1. A unit case to which a photoelectric element and a lens are attached, a front cover attached to the unit case, and a filter plate provided between the unit case and the front cover. In the unit case, a step portion for accommodating the filter plate is formed in the unit case, and the inner peripheral edge portion of the step portion is pressed and fixed by being melted by an ultrasonic welding device. A photoelectric sensor characterized in that a holding protrusion is provided.