JP2014089805A - Photoelectronic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectronic sensor having a structure which prevents plates attached to windows of a case from falling more securely.SOLUTION: A photoelectronic sensor (100) includes: plates (3a, 3b) attached to windows (2a, 2b) of a case (2); and a falling prevention member (a bracket (5)) fixed to the case (2) while being attached to a surface where the windows (2a, 2b) of the case (2) are formed. When the plates (3a, 3b) are viewed in a plane view, the bracket (5) overlaps with at least parts of peripheral parts of the plates (3a, 3b). In the structure, even if the plates (3a, 3b) are removed from the windows (2a, 2b) of the case (2), the plates are received by the bracket (5).

Description

  The present invention relates to a photoelectric sensor.

  Conventionally, a photoelectric sensor for detecting the presence or absence of an object has been used. Such a photoelectric sensor generally includes a light projecting unit and a light receiving unit. The light projecting unit and the light receiving unit are housed in one case or separate cases.

  A window is formed in the case. The light projecting unit projects light to the outside of the photoelectric sensor through the window. The light receiving part receives light incident on the inside of the case through the window of the case. For example, Japanese Patent No. 431342 (Patent Document 1) discloses a case in which a light receiving window is formed.

Japanese Patent No. 431342

  In general, in a case that houses the optical component as described above, a plate is attached to the window of the case in order to prevent water or dust from entering the case. The plate is fixed to the window with, for example, an adhesive or a double-sided tape.

  On the other hand, the above photoelectric sensor is installed in a production line, for example. In a production line, vibrations can occur due to machine operation. When the vibration is transmitted to the photoelectric sensor, the plate may drop from the case. It is also conceivable that the plate may fall out of the case due to aged deterioration of an adhesive or the like that fixes the photoelectric sensor plate to the case.

  It is necessary to avoid mixing photoelectric sensor plates into the product. For example, in a food production line, contamination of plates as foreign matters becomes a serious problem. It is not limited to such an example, and it is required to prevent the photoelectric sensor plate from dropping off as much as possible.

  An object of the present invention is to provide a photoelectric sensor having a structure that can more reliably prevent a plate attached to a window of a case from dropping off.

  A photoelectric sensor according to an aspect of the present invention includes a case having a surface on which a window is formed, an optical component that is accommodated in the case and projects or receives light through the window, and a plate that is attached to the window of the case. And a drop-off preventing member that is fixed to the case in a state where it covers the surface on which the window of the case is formed and overlaps at least a part of the peripheral edge of the plate when the plate is viewed in plan.

  According to this configuration, even when the plate is detached from the window of the case, the plate can be received by the drop-off preventing member. Accordingly, it is possible to prevent the plate from falling off more reliably. Note that the dropout prevention member may be in contact with the plate, or there may be a gap between the dropout prevention member and the plate.

  Preferably, the optical component includes a light projecting unit and a light receiving unit. The window includes a first window for passing light from the light projecting unit to the outside of the case and a second window for allowing light from the outside of the case to pass to the light receiving unit. The plate includes a first plate attached to the first window and a second plate attached to the second window. The drop-off prevention member has a first opening formed at a position corresponding to the first plate, and a second opening formed at a position corresponding to the second plate.

  According to this configuration, in the photoelectric sensor including the light projecting unit and the light receiving unit, both of the first plate mounted on the window of the light projecting unit and the second plate mounted on the window of the light receiving unit are removed. Can be prevented.

Preferably, the case has a locking portion for locking the drop-off preventing member.
According to this structure, workability | operativity at the time of attaching a drop-off prevention member to a case can be improved.

Preferably, the drop-off prevention member has a crimping portion that is crimped to the case.
Preferably, the drop-off preventing member has a welded portion welded to the case.

  According to said structure, a drop-off prevention member can be more reliably fixed to a case. Therefore, it is possible to more reliably prevent the plate from falling off.

  According to the present invention, it is possible to more reliably prevent the plate attached to the window of the case from dropping off.

1 is an external view of a photoelectric sensor according to an embodiment of the present invention. It is the perspective view which showed the light projection window and light reception window of the photoelectric sensor shown in FIG. It is the figure which showed typically the cross section of the plate, case, and bracket in the surface parallel to the X-axis shown in FIG. It is a block diagram for demonstrating the structure regarding the optical system of the photoelectric sensor 100 shown in FIG. It is typical sectional drawing for demonstrating the state with which the plate was mounted | worn to the case. It is the figure which showed an example of the structure of the case for attaching a plate to the window of a case. It is the figure which showed the other example of the structure of the case for mounting | wearing the window of a case with a plate. It is the figure which showed another example of the structure of the case for mounting | wearing the window of a case with a plate. It is the figure which showed the example of the other structure for fixing a bracket (drop-off prevention member) to a case.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is an external view of a photoelectric sensor according to an embodiment of the present invention. FIG. 2 is a perspective view showing a light projecting window and a light receiving window of the photoelectric sensor shown in FIG.

  1 and 2, photoelectric sensor 100 detects the presence or absence of an object, for example, by light projection and light reception. The photoelectric sensor 100 detects the presence or absence of a product on the production line 150, for example. Note that the use of the photoelectric sensor 100 is not particularly limited.

  The photoelectric sensor 100 has a case 2. As will be described in detail later, the case 2 houses a light projecting unit and a light receiving unit. The light projecting unit includes, for example, a light emitting unit that emits light and a lens that transmits light from the light emitting unit. The light receiving unit includes a light receiving element that receives light and a lens that collects light on a light receiving surface of the light receiving element.

  The case 2 is formed with a light projection window 2 a for allowing light emitted from the light emitting portion through the lens to pass therethrough and a light receiving window 2 b for introducing reflected light into the case 2. Plates 3a and 3b are mounted on the light projecting window 2a and the light receiving window 2b, respectively.

  The photoelectric sensor 100 further includes a bracket 5. The bracket 5 is fixed to the case 2 in a state of covering the surface of the case 2 on which the light projection window 2a and the light receiving window 2b are formed. In the bracket 5, openings 5a and 5b are formed at positions corresponding to the plates 3a and 3b, respectively. When the plates 3a and 3b are viewed in plan (viewing the plates 3a and 3b from a direction perpendicular to both the X direction and the Y direction in FIG. 2), the bracket 5 overlaps at least a part of the peripheral edge of the plates 3a and 3b. It is formed as follows. As shown in FIG. 2, when the width in the X-axis direction of the openings 5a and 5b is W1, and the width in the X-axis direction of the plates 3a and 3b is W2, W1 <W2. Further, the end 5a1 of the opening 5a in the Y direction is located inside the plate 3a with respect to the end 3a1 of the plate 3a. Similarly, the end 5b1 of the opening 5b in the Y direction is located on the inner side of the plate 3b than the end 3b1 of the plate 3b.

  That is, at least a part of the outline of the openings 5a and 5b is inside the plate. Therefore, even when one or both of the plates 3a and 3b are removed from the window, the bracket 5 receives the plate, so that the plates 3a and 3b can be prevented from falling off.

  The bracket 5 does not need to be in close contact with the plates 3a and 3b. A gap may be formed between the bracket 5 and the case 2 to such an extent that the plates 3a and 3b can be prevented from falling off.

  The case 2 is formed with a locking portion 2 c for locking to the bracket 5. The bracket 5 has a lock receiving portion 5c in which a hole for receiving the lock portion 2c is formed. The locking portion 2c and the locking receiving portion 5c are located on the side surface 21 adjacent to the surface of the case 2 where the light projection window 2a and the light receiving window 2b are formed. That is, the latch receiving portion 5c is formed so as to be bent from the surface of the bracket 5 in which the openings 5a and 5b are formed.

  In addition, the latching | locking part 2c is formed also in the side surface 22 located in the opposite side to the side surface 21 of the case 2 shown by FIG. Therefore, the bracket 5 also has the latch receiving part 5c not only on the side surface 21 side of the case 2 but also on the side surface 22 side.

  FIG. 3 is a diagram schematically showing a cross section of the plate, the case, and the bracket on a plane parallel to the X axis shown in FIG. Referring to FIG. 3, the case 2 is formed with a claw portion as a locking portion 2c. The bracket 5 is fixed to the case by passing the hole in which the latch receiving portion 5c of the bracket 5 is formed through the latch portion 2c.

  FIG. 4 is a block diagram for explaining a configuration related to the optical system of the photoelectric sensor 100 shown in FIG. Referring to FIG. 2, photoelectric sensor 100 includes a light emitting unit 12, a light projecting lens 14, a light receiving lens 16, and a light receiving element 18.

  The light emitting unit 12 is a light source that emits light, such as a laser diode or an LED. The light projecting lens 14 receives light from the light emitting unit 12. The light that has passed through the light projecting lens 14 is emitted to the outside of the case 2.

  The light receiving lens 16 receives light incident on the inside of the case 2 from the outside of the case 2 and collects light on the light receiving surface of the light receiving element 18. The light receiving element 18 receives light from the light receiving lens 16 and outputs a light receiving signal representing the amount of light received. The light reception signal from the light receiving element 18 is processed by a signal processing circuit (not shown).

  The signal processing circuit may be provided inside the case 2. Alternatively, the photoelectric sensor 100 may be a switch of a type in which an optical head and a signal processing circuit are separated. In the case of this configuration, the light reception signal output from the light receiving element 18 is sent to a signal processing circuit (for example, disposed in the amplifier unit) through a cable, for example.

  FIG. 5 is a schematic cross-sectional view for explaining a state where the plate is mounted on the case. Referring to FIG. 5, plates 3a and 3b are respectively attached to light projecting window 2a and light receiving window 2b formed in case 2, and are fixed to case 2 with an adhesive, a double-sided tape or the like. The plates 3a and 3b may be welded to the case.

  Thus, the inside of the case 2 can be sealed by attaching the plates to the light projection window 2a and the light reception window 2b. Therefore, it is possible to prevent water or dust from entering the case.

  However, in the production line, vibration can occur due to the operation of the machine. When the vibration is transmitted to the photoelectric sensor, the plates 3a and 3b may drop from the case. Moreover, it is also conceivable that the plates fall out of the case due to aging deterioration of an adhesive or the like that fixes the plates 3a and 3b to the case 2.

  Here, as a structure for fixing the plate to the case, for example, the following can be considered. For example, as shown in FIG. 6, the periphery of the plate 3a is formed as a flange. The plate 3a is fitted into the projection window 2a from the inside of the case 2. Or as shown in FIG. 7, a step is formed in the peripheral part of the light projection window 2a. The plate 3a is attached to the step portion. Or as FIG. 8 shows, a groove | channel is formed in the peripheral part of the light projection window of case 2, and the plate 3a is inserted in the groove | channel. 6 to 8, the light receiving window 2b and the plate 3b are not shown, but the above-described configuration is also used for fixing the plate 3b to the case 2.

  In order to prevent the plate from falling off more reliably, it is necessary to increase the size of the portion for hooking the plate on the case. For example, in the configuration shown in FIG. 6, it is necessary to enlarge the ridge portion of the plate 3a. When such a method is adopted, the plate becomes large. In order to avoid interference between the light projecting plate and the light receiving plate, the size of the case must be increased.

  Further, according to the configuration shown in FIG. 7 or FIG. 8, it is necessary to increase the length of the step formed in the case or the depth of the groove. On the other hand, when the light projection window or the light receiving window is narrowed, the detection performance of the photoelectric sensor may be affected. For example, if the amount of light received is reduced by reducing the size of the light receiving window, it is likely that false detection is likely to occur. If the length of the step formed in the case or the depth of the groove is increased while keeping the light projection window or the light receiving window as narrow as possible, the case may be enlarged.

  As shown in FIG. 1, according to the embodiment of the present invention, the plate 5 can be received by the bracket 5 even if the plates 3 a and 3 b attached to the case 2 come off the window. As a result, the plate can be prevented from falling off the optical switch.

  Furthermore, when an impact is directly applied to the plates 3a and 3b, there is a high possibility that the plate will fall off the optical switch. Since the bracket 5 is formed so as to cover a part of the plates 3a and 3b, the area of the exposed portion of the plates 3a and 3b is reduced. Therefore, the possibility that an impact is directly applied to the plates 3a and 3b can be reduced. Therefore, also from this point, it is possible to prevent the plates 3a and 3b from falling off.

  For example, in a food production line, contamination of plates as foreign matters becomes a serious problem. According to this embodiment, it is possible to prevent the plate from falling off more reliably, so that the possibility of the above problems occurring can be reduced. Moreover, it is not limited to the example of the production line of foodstuffs, The mixing of the foreign material into a product becomes a problem. According to the embodiment of the present invention, in application of the photoelectric sensor to such various production lines, it is possible to prevent the plate from falling off from the photoelectric sensor.

  Further, even when the plate is attached to the window by the configuration shown in FIGS. 6 to 8, the plate ridge portion or the case step portion is reduced, or the depth of the groove formed in the case is reduced. Can be made smaller. Therefore, for example, the case can be downsized.

  In the above embodiment, the bracket 5 is attached to the case 2 by passing the hole of the latch receiving portion 5c of the bracket 5 through the latch portion 2c (claw portion) formed in the case 2. According to such a configuration, it is possible to improve workability when attaching the bracket 5 (drop-off preventing member) to the case 2. However, the position and number of the locking portions 2c are not particularly limited. For example, instead of the side surfaces 21 and 22 of the case 2 shown in FIG. 2, locking portions 2 c may be formed on the side surfaces 23 and 24 of the case 2. That is, the locking portion may be formed on any surface as long as it is a side surface in contact with the surface of the case in which the window is formed.

  In FIG. 2, two locking portions are formed on each of the side surfaces 21 and 22. However, one locking portion may be formed on each of the side surfaces 21 and 22.

  Furthermore, as shown in FIG. 9, the locking portion 2 c may not be formed on the side surface of the case 2. According to the configuration shown in FIG. 9, the bracket 5 includes an attachment portion 5d instead of the latch receiving portion. The bracket 5 can be fixed to the case 2 by crimping the mounting portion 5d to the case 2, for example. Further, the attachment portion 5d may be weldable to the case 2. The bracket 5 can be fixed to the case 2 by welding the attachment portion 5 d to the case 2. Of course, the attachment portion 5d may be welded to the case 2 after the attachment portion 5d is pressure-bonded to the case 2. With such a configuration, the bracket 5 can be more securely fixed to the case 2. Therefore, it is possible to more reliably prevent the plates 3a and 3b from falling off.

  Further, in the above embodiment, the photoelectric switch including the light projecting unit and the light receiving unit is shown. However, only the light projecting unit or the light receiving unit is accommodated in the case, and 1 corresponding to the light projecting unit or the light receiving unit. Two windows may be formed on the side of the case.

  The embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  2 Case, 2a Light emitting window, 2b Light receiving window, 2c Locking part, 3a, 3b plate, 3a1, 3b1 End part (plate), 5a1, 5b1 End part (opening part), 5 Bracket, 5a, 5b Opening part, 5c Locking receiving portion, 5d mounting portion, 12 light emitting portion, 14 light projecting lens, 16 light receiving lens, 18 light receiving element, 21-24 side surface (case), 100 photoelectric sensor, 150 production line.

Claims (5)

A case having a surface on which a window is formed;
An optical component housed in the case for projecting or receiving light through the window;
A plate attached to the window of the case;
A drop-off preventing member that is fixed to the case in a state where it covers the surface of the case where the window is formed, and overlaps at least a part of the peripheral edge of the plate when viewed in plan. Photoelectric sensor. The optical component includes a light projecting unit and a light receiving unit,
The window is a first window for passing light from the light projecting unit to the outside of the case and a second window for passing light from the outside of the case to the light receiving unit,
The plate is
A first plate mounted on the first window;
A second plate attached to the second window;
The said drop-off preventing member has a first opening formed at a position corresponding to the first plate and a second opening formed at a position corresponding to the second plate. The photoelectric sensor according to 1.   The photoelectric sensor according to claim 1, wherein the case has a locking portion for locking the drop-off prevention member.   The photoelectric sensor according to claim 1, wherein the drop-off preventing member has a pressure-bonding portion that is pressure-bonded to the case. The photoelectric sensor according to claim 1, wherein the drop-off prevention member has a welded portion welded to the case.

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