JP2021139757A - Optical sensor - Google Patents

Abstract

To provide an optical sensor that can effectively escape heat generated from a plurality of circuit boards.SOLUTION: An optical sensor 1 includes: a housing 2; a plurality of circuit boards 31, 32 in the housing 2; a pair of heat conduction members 41, 42; and a metal plate 5. The pair of heat conduction members 41, 42 are arranged between the circuit boards 31 and 32 next to each other. The metal plate 5 is in the shape of a band with a first end part 51 and a second end part 52 located on opposite sides. The first end part 51 is inserted between the pair of heat conduction members 41 and 42. The second end part 52 is thermally connected to the housing 2.SELECTED DRAWING: Figure 2

Description

The present invention relates to an optical sensor.

Optical sensors such as photoelectric sensors and image sensors installed on the production line of a factory can measure physical quantities by an optical system without touching an object. The optical sensor is suitable for a waterproof structure because it can measure even if the housing is sealed. Further, the optical sensor is suitable for an ultra-small sensor because it does not require a mechanically operating component.

A circuit board that constitutes a control unit of an optical sensor or the like is built in the housing. When a high-performance optical sensor capable of detecting various workpieces is configured, the size of the circuit board becomes large due to complicated processing. Instead of increasing the size of the housing according to the circuit board, the circuit board may be divided into smaller sizes that can be accommodated in the housing and arranged in the housing in small portions.

However, if a plurality of circuit boards are arranged close to each other in a narrow housing, heat may be trapped between the circuit boards, causing the optical sensor to malfunction or be damaged. In particular, if the housing is sealed or the space inside the housing is narrow, heat tends to be trapped between the circuit boards.

Therefore, an object of the present invention is to provide an optical sensor capable of efficiently dissipating heat generated from a plurality of circuit boards.

The optical sensor according to one aspect of the present disclosure includes a housing, a plurality of circuit boards housed in the housing, a pair of heat conductive members, and a metal plate. The pair of heat conductive members are arranged between adjacent circuit boards. The metal plate is formed in a strip shape having a first end portion and a second end portion opposite to the first end portion. The first end is inserted between a pair of heat conductive members. The second end is thermally connected to the enclosure.

According to this aspect, the first end of the metal plate is arranged between adjacent circuit boards. Each circuit board and the metal plate are thermally connected by a heat conductive member. Therefore, in the space sandwiched between the circuit boards where heat is easily stored, the heat generated from the plurality of circuit boards can be efficiently released to the housing via the metal plate.

In the above aspect, at least one of the plurality of circuit boards has a first surface facing the metal plate and a second surface opposite to the first surface. Electronic components may be mounted on both the first surface and the second surface.

According to this aspect, electronic components can be mounted at high density to form a highly functional optical sensor. Even in a circuit board on which electronic components are mounted on both sides, heat can be efficiently dissipated in this embodiment.

In the above aspect, it may further have an insulating film covering the surface of the metal plate. However, it is preferable that at least a part of the first end portion is not covered with an insulating film.

According to this aspect, since the metal plate is covered with the insulating film, it is possible to prevent the possibility that the metal plate comes into contact with the metal plate and short-circuits the wiring or the like in the housing. On the other hand, since at least a part of the first end portion is exposed from the insulating film, good thermal conductivity can be obtained at a portion facing an electronic component (for example, a CPU) having a large calorific value.

In the above aspect, the housing includes a first wall and a second wall opposite to the first wall. The plurality of circuit boards and the first end portion are arranged along the first wall. The second end is preferably thermally connected to a second wall on the opposite side of the plurality of circuit boards.

According to this aspect, since the second end portion of the metal plate is connected to the second wall where the temperature is less likely to rise than the first wall near the circuit board, it is easy to secure the temperature difference. Heat can be efficiently dissipated from the circuit board to the housing.

In the above aspect, the housing is preferably made of a metal material.

According to this aspect, heat can be efficiently dissipated to a housing having excellent thermal conductivity.

In the above aspect, the heat conductive member may be an adhesive heat radiating sheet. The heat radiating sheet is formed of a resin material and adheres to a circuit board and a metal plate.

According to this aspect, since the heat conductive member is a heat radiating sheet, the heat conductive member can be easily obtained at low cost.

According to the present invention, it is possible to provide an optical sensor capable of efficiently dissipating heat generated from a plurality of circuit boards.

FIG. 1 is a perspective view showing an optical sensor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, those having the same reference numerals have the same or similar configurations. In FIGS. 1 and 2, as an example of the optical sensor 1, a photoelectric sensor including a light emitting unit that emits light and a light receiving unit that receives light is disclosed. The amount of light that reaches the light receiving unit changes when the projected light is blocked or reflected by the work. The photoelectric sensor can detect this change, convert it into an electric signal, and output it to an external device.

However, the optical sensor 1 is not limited to the photoelectric sensor. The optical sensor 1 may be a displacement sensor that measures the distance from the sensor to the object by detecting the amount of physical change of the object with an optical element and calculating the amount of change as a distance, or with a camera. It may be an image sensor that calculates the area, center of gravity, length, position, etc. of the object by image processing the captured image and outputs data and judgment results, or reads a barcode or two-dimensional code. It may be a code reader.

In the optical sensor 1 of the embodiment of the present invention, a pair of heat conductive members 41 and 42 are arranged between adjacent circuit boards 31 and 32, and the metal plate 5 is sandwiched between the heat conductive members 41 and 42. The heat generated from the circuit boards 31 and 32 can be efficiently dissipated through the metal plate 5. Hereinafter, each configuration will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view showing an optical sensor 1 according to an embodiment of the present invention. In the illustrated example, the optical sensor 1 is configured as a retroreflective photoelectric sensor, has a light projecting unit 11, a light receiving unit 12, an amplifying unit 13, a control unit 14, and the like, and is connected to an external power source via a cable 15. Has been done. The optical sensor 1 may be configured as a transmissive photoelectric sensor, and the light projecting unit 11 and the light receiving unit 12 may be housed in separate housings 2 and 2, respectively. The amplification unit 13 may be configured as an amplifier-separated photoelectric sensor separated from the housing 2, or the power supply unit may be configured as a power supply built-in photoelectric sensor built in the housing 2.

The housing 2 is made of a metal material such as stainless steel or zinc die-cast, except for the window portions 11W and 12W provided with the light emitting portion 11 and the light receiving portion 12. However, the material of the housing 2 is not limited to the metal material. For example, the housing 2 may be formed from a resin material such as polybutylene terephthalate resin or ABS resin. The windows 11W and 12W are formed of a translucent material such as methacrylic resin or glass.

FIG. 2 is a cross-sectional view taken along the line II-II in FIG. As shown in FIG. 2, the housing 2 includes a case body 20 formed in a substantially rectangular parallelepiped cup shape, and a lid 21 covering the opening of the case body 20. The case body 20 includes a bottom wall 22 and a peripheral wall 23 that stands up from the bottom wall 22 and extends toward the lid 21. In the housing 2, the bottom wall 22 is located on the opposite side of the lid 21.

A plurality of circuit boards 31, 32, ... Arranged in parallel are housed in the housing 2. In the illustrated example, two circuit boards 31 and 32 arranged in parallel are housed in the housing 2. Although not shown, three or more circuit boards arranged in parallel may be housed in the housing 2. The circuit board 31 is arranged along the first wall of the housing 2. The adjacent circuit boards 32 are arranged along the circuit board 31.

In the illustrated example, the circuit board 31 is arranged along the lid 21. The lid 21 is an example of the first wall, and the bottom wall 22 is an example of the second wall located on the opposite side of the housing 2 from the first wall. The bottom wall 22 may be the first wall and the lid 21 may be the second wall. In the following description, they may be referred to as a first circuit board 31, a second circuit board 32, and a third circuit board in order from the first wall (for example, the lid 21).

The first circuit board 31 is formed in a flat plate shape having a first surface 31A and a second surface 31B on the opposite side of the first surface 31A. Similarly, the second circuit board 32 is formed in a flat plate shape having a first surface 32A and a second surface 32B on the side opposite to the first surface 32A. The adjacent circuit boards 31 and 32 are arranged so that the first surfaces 31A and 32A face each other.

Electronic components 39 are mounted on both sides 31A and 31B of the first circuit board 31. Similarly, the electronic components 39 are mounted on both sides 32A and 32B of the second circuit board 32. The electronic component 33 may be mounted on only one of the first and second surfaces 31A and 31B, or the electronic component 39 may be mounted on only one of the first and second surfaces 32A and 32B. May be good. The electronic components 39 mounted on the plurality of circuit boards 31, 32, ... Consists of, for example, the amplification unit 13 and the control unit 14 described above.

In the adjacent circuit boards 31 and 32, a pair of heat conductive members 41 and 42 are arranged between the first surfaces 31A and 32A facing each other. In other words, in the pair of circuit boards 31, 32 and the pair of heat conductive members 41, 42, one heat conductive member 41 is attached to one circuit board (for example, the first circuit board 31), and the other circuit board (for example). For example, the other heat conductive member 42 is attached to the second circuit board 32). In the following description, one heat conductive member 41 may be referred to as a first heat conductive member 41, and the other heat conductive member 42 may be referred to as a second heat conductive member 42.

One of the features of this embodiment is that the metal plate 5 is sandwiched between the heat conductive members 41 and 42. When there are three or more circuit boards arranged in parallel, a pair of heat conductive members 41, between the first surfaces 31A and 32A, and between the second surfaces 31B and 32B and the third circuit board, 42 may be arranged and an additional metal plate 5 may be sandwiched.

The first surfaces 31A and 32A have irregularities. In particular, when the electronic component 39 is mounted on the first surfaces 31A and 32A, the unevenness is large. The heat conductive members 41 and 42 are in close contact with each other so as to fill the gap between the first surfaces 31A and 32A and the metal plate 5, and improve the heat conductivity from the circuit boards 31 and 32 to the metal plate 5. An example of the heat conductive members 41 and 42 is an adhesive heat radiating sheet formed of a resin material. However, the heat conductive members 41 and 42 are not limited to the heat radiating sheet. For example, it may be a heat conductive paste filled between the first surfaces 31A and 32A and the metal plate 5.

The metal plate 5 has a first end portion 51, a second end portion 52 on the opposite side of the first end portion 51, and a connecting portion 53 connecting the first and second end portions 51 and 52. It is formed in a band shape. The metal plate 5 is formed of a metal material having excellent thermal conductivity such as copper, and its surface is covered with an insulating film. However, an insulating film is not intentionally formed on at least a part of the first end portion 51.

The first end portion 51 is inserted between the pair of heat conductive members 41 and 42. The second end 52 is thermally connected to the housing 2. Specifically, the second end portion 52 may be directly fixed to the second wall 22 and the second end portion 52 and the second wall 22 may be thermally connected, or the second end portion 52 may be thermally connected via a heat radiating sheet or the like. The end 52 may be thermally connected to the second wall 22.

According to the optical sensor 1 of the present embodiment configured as described above, the first end portion 51 of the metal plate 5 is arranged between the adjacent circuit boards 31 and 32. The circuit boards 31 and 32 and the metal plate 5 are thermally connected by heat conductive members 41 and 42. Therefore, in the space sandwiched between the circuit boards 31 and 32 where heat is easily stored, the heat generated from the plurality of circuit boards 31 and 32 can be efficiently released to the housing 2.

Electronic components 39 are mounted on both sides of the first and second surfaces 31A and 31B of the circuit board 31. Similarly, the electronic components 39 are mounted on both sides of the first and second surfaces 32A and 32B of the circuit board 32. According to this embodiment, the electronic component 39 can be mounted at a high density to form a highly functional optical sensor 1. Even if the circuit boards 31 and 32 have the electronic components 39 mounted on both sides, heat can be efficiently dissipated in the present embodiment.

The surface of the metal plate 5 is covered with an insulating film. However, at least a part of the first end portion 51 is not covered with the insulating film. According to the present embodiment, since the metal plate 5 is covered with the insulating film, it is possible to prevent the metal plate 5 from coming into contact with the metal plate 5 and causing a short circuit in the wiring or the like in the housing 2. On the other hand, since at least a part of the first end portion 51 is exposed from the insulating film, good thermal conductivity can be obtained at a portion facing an electronic component (for example, a CPU) having a large calorific value.

The second end 52 of the metal plate 5 is connected to a second wall (for example, the bottom wall 22) whose temperature is less likely to rise than the first wall (for example, the lid 21) close to the circuit boards 31 and 32. .. The housing 2 is preferably made of a metal material. According to this embodiment, since it is easy to secure the temperature difference between the metal plate 5 and the housing 2, the heat from the circuit boards 31 and 32 can be efficiently dissipated. The heat conductive members 41 and 42 may be commercially available heat radiating sheets. If the heat conductive members 41 and 42 are heat radiating sheets, they can be easily obtained at low cost.

The embodiments described above are for facilitating the understanding of the present invention, and are not for limiting and interpreting the present invention. Each element included in the embodiment and its arrangement, material, condition, shape, size, and the like are not limited to those exemplified, and can be changed as appropriate. In addition, the configurations shown in different embodiments can be partially replaced or combined.

[Additional Notes]
Housing (2) and
A plurality of circuit boards (31, 32, ...) Housed in the housing (2), and
A pair of heat conductive members (41, 42) arranged between the adjacent circuit boards (31, 32) and
It is formed in a strip shape having a first end portion (51) and a second end portion (52) opposite to the first end portion (51), and the first end portion (51) is a pair of the heat conduction. A metal plate (5) inserted between the members (41, 42) and the second end (52) thermally connected to the housing (2).
An optical sensor (1).

1 ... optical sensor, 2 ... housing, 5 ... metal plate, 11 ... light projecting unit, 12 ... light receiving unit, 13 ... amplification unit, 14 ... control unit, 15 ... cable, 20 ... case body, 21 ... lid ( 1st wall example), 22 ... bottom wall (2nd wall example), 23 ... peripheral wall, 31 ... 1st circuit board (circuit board example), 32 ... second circuit board (circuit board example), 31A , 32A ... 1st surface, 31B, 32B ... 2nd surface, 39 ... Electronic component, 41 ... 1st heat conductive member (one of a pair of heat conductive members), 42 ... 2nd heat conductive member (a pair of heat conductive members) The other), 51 ... 1st end, 52 ... 2nd end, 53 ... Connection.

Claims (6)

With the housing
A plurality of circuit boards housed in the housing and
A pair of heat conductive members arranged between adjacent circuit boards,
It is formed in a strip shape having a first end portion and a second end portion opposite to the first end portion, and the first end portion is inserted between a pair of the heat conductive members, and the second end portion is formed. With a metal plate thermally connected to the housing,
Equipped with an optical sensor. At least one of the plurality of circuit boards has a first surface facing the metal plate and a second surface opposite to the first surface.
The optical sensor according to claim 1, wherein electronic components are mounted on both the first surface and the second surface. Further having an insulating film covering the surface of the metal plate,
The optical sensor according to claim 1 or 2, wherein at least a part of the first end portion is not covered with the insulating film. The housing includes a first wall and a second wall on the opposite side of the first wall.
The plurality of circuit boards and the first end portion are arranged along the first wall.
The optical sensor according to any one of claims 1 to 3, wherein the second end portion is thermally connected to the second wall. The optical sensor according to any one of claims 1 to 4, wherein the housing is made of a metal material. The optical sensor according to any one of claims 1 to 4, wherein the heat conductive member is an adhesive heat radiating sheet formed of a resin material and in close contact with the circuit board and the metal plate.

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