JP5050181B2 - Photosensor for transmissive photoelectric sensor - Google Patents

Description

  The present invention relates to a light receiver of a transmission type photoelectric sensor.

  The transmissive photoelectric sensor includes a light projector and a light receiver that are arranged to face each other with a detection area interposed therebetween, and determines that there is an object in the detection area when light between the light projector and the light receiver is blocked.

  In recent years, the downsizing (reduction in diameter) of the photoreceiver of the transmission type photoelectric sensor has been advanced (for example, see Patent Document 1). When a small light receiver is configured using a shell-type light receiving element such as a phototransistor, as shown in FIG. 14 of Patent Document 1, the light receiving element 52 has a light receiving portion of a light receiving device (light receiving head) 500. It is arranged to face the front end side.

  However, the use of a shell-type light receiving element has a limit in miniaturization. In view of this, a proposal has been made to further reduce the size of the light receiver by using a surface-mounted (chip-type) light receiving element such as a photo IC.

When a photo IC is used and the case inner diameter of the light receiver is very small, the light receiving portion of the photo IC cannot be directed to the front end side of the light receiver. In this case, as shown in FIG. 7A, the light receiving portion 24a of the photo IC 24 is arranged to face the radial direction. The incident light L from the outside is collected by the lens 26 disposed at the front end of the light receiver 21, and is received by the light receiving unit 24 a of the photo IC 24 through the mirror 27.
JP 2006-236849 A

  However, in the case of the light receiver 21 shown in FIG. 7A, the light L incident from the lower half of the lens 26 is blocked by the side surfaces of the circuit board 23 and the photo IC 24 and is not received by the light receiving unit 24a. That is, as shown on the left side of FIG. 7A, the effective surface of the lens surface 26d is only the upper half (hatched portion), and the amount of received light is reduced, making it impossible to increase the operating distance of the photoelectric sensor. Here, even in the light receiver 21 of FIG. 7A, the amount of received light can be improved by shifting the positions of the photo IC 24 and the circuit board 23 to the rear end side (right side of the drawing) of the light receiver 21. However, all the light L incident on the lens 26 could not be received by the light receiving unit 24a.

  Further, in order to secure the amount of received light, the position of the light receiving portion 24a of the photo IC 24 needs to be arranged near the central axis 22a of the case 22, but as a result, as shown in FIG. It is located near the inner wall of the case 22. In this case, compared with the case where the circuit board 23 is disposed near the case center axis 22a, the circuit board 23 cannot have a sufficient width w, and the space height h between the circuit board 23 and the inner wall of the case 22 is small. Thus, there is a problem that it is difficult to arrange electronic components on the lower surface of the circuit board 23.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light receiving device for a transmission type photoelectric sensor provided with a surface mount type photo IC, which is small and has a long operating distance. There is to do.

  In order to solve the above-described problems, the present invention provides a photo IC, a circuit board on which the photo IC is mounted and driven, and a cylindrical case, the circuit being arranged so that a light receiving portion of the photo IC faces a radial direction. A case that accommodates a board; a cable that is connected to a circuit on the circuit board and that extends from one opening of the case; and is disposed in the other opening of the case, and receives incident light from outside the photo A lens that condenses in the vicinity of the light receiving part of the IC, and a mirror that is disposed in the vicinity of the focal point of the lens and reflects the incident light collected by the lens and causes the light receiving part of the photo IC to receive the light. In the light receiving device of the transmissive photoelectric sensor, the circuit board is disposed in the vicinity of the central axis of the case, and the light receiving portion of the photo IC is shifted in one radial direction from the central axis of the case. Disposed at a position where the center of curvature of the lens surface of the lens is displaced from the center axis of the case in the same direction as the one radial direction, and the radius of curvature of the lens surface is greater than or equal to the inner diameter of the case And providing a light receiving device for a transmission type photoelectric sensor, wherein the incident light is received by the light receiving portion of the photo IC by setting the inner diameter of the case to three times or less. It is.

  The present invention also provides a light receiving device for a transmissive photoelectric sensor, characterized in that, in the above configuration, the lens extends to a position where it abuts on the mirror.

  In the photoreceiver of the transmission photoelectric sensor according to the present invention, the circuit board on which the photo IC is mounted is disposed in the vicinity of the center axis of the case, that is, at the position where the width is maximum in the case. Therefore, the light receiver according to the present invention can make the inner diameter of the case smaller than that of the conventional light receiver if the width of the circuit board is the same.

  In addition, since the circuit board is arranged near the central axis of the case, the distance between the lower surface of the circuit board and the inner wall of the case is increased as compared with the conventional one. Therefore, according to the light receiver of the present invention, the electronic components can be easily arranged on the lower surface of the circuit board.

  In the light receiver of the present invention, substantially all of the light that is parallel to the central axis of the case and incident on the lens surface is condensed at the focal point without being blocked by the circuit board or the like. ing. The condensed light is received by the light receiving portion of the photo IC without passing through the mirror. That is, the light receiver of the present invention can make the entire lens surface an effective surface, and can increase the amount of received light. Therefore, according to the light receiver of the present invention, it is possible to configure a photoelectric sensor having a long operating distance while being small.

[Constitution]
Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an example of a light receiver of a transmission photoelectric sensor according to the present invention, and FIG. 2 is a perspective view showing a state in which the case of the light receiver in FIG. 1 is omitted. 3 is a cross-sectional view showing the light receiver of FIG. 1, and FIG. 4 is a front view showing a case, a circuit board, and a photo IC of the light receiver of FIG. FIG. 5 is a diagram for explaining the action of the lens in the light receiver of FIG.

  As shown in FIGS. 1 to 4, the photoreceiver 1 of the transmission photoelectric sensor according to the present embodiment includes a cylindrical case 2, a circuit board 3 housed in the case 2, and a circuit board 3. The photo IC 4 and the cable 5 connected to the circuit, the lens 6 provided at the front end of the case 2, and the mirror 7 disposed in the vicinity of the photo IC 4 are configured.

  The case 2 is made of metal, and an M5 screw is cut on the outer peripheral surface as shown in FIG. Further, the inner diameter of the case 2 is about 3.7 mm.

  The circuit board 3 is formed with a width (length in the short direction) of 3 mm and a thickness of about 0.5 mm so as to be accommodated in the case 2. A photo IC 4 and electronic components (not shown) for driving the photo IC 4 are mounted on a circuit (not shown) formed on the upper and lower surfaces of the circuit board 3.

  The circuit board 3 on which the photo IC 4 is mounted is disposed near the central axis 2a of the case 2 as shown in FIGS. As a result, the photo IC 4 mounted on the circuit board 3 is arranged at a position shifted in the radial direction from the central axis 2 a of the case 2.

  As shown in FIG. 2, the photo IC 4 has substantially the same width as the width of the circuit board 3. The photo IC 4 generates a light reception signal according to the light incident on the light receiving unit 4a via the lens 6 and the mirror 7.

  As shown in FIGS. 2 and 3, the cable 5 has one end connected to the circuit of the circuit board 3 and the other end extending outward from the opening at the rear end of the case 2. A cable bush 5a is provided between the cable 5 and the case 2, and the opening at the rear end of the case 2 is sealed. The other end of the cable 5 is connected to an external device (not shown), and a light reception signal from the photo IC 4 is transmitted to the external device.

  The lens 6 is made of resin such as acrylic, and is disposed so as to close the opening at the front end of the case 2 as shown in FIG. The lens 6 has a base portion 6 a housed in the case 2 and a protruding portion 6 b that protrudes from an opening at the front end of the case 2.

  The base 6 a has an outer diameter that is substantially the same as the inner diameter of the case 2 so as to be fitted to the case 2. The base 6 a extends to the position of the light receiving portion 4 a of the photo IC 4 on the circuit board 3 arranged in the case 2. The base 6a further has a recess 6c into which the front end of the circuit board 3 is inserted. By inserting the front end of the circuit board 3 into the recess 6c, the lens 6 and the circuit board 3 are engaged.

  The protrusion 6 b has an outer diameter slightly larger than the inner diameter of the case 2, and comes into contact with the front end surface of the case 2. A lens surface 6d is formed on the front end surface of the protrusion 6b.

  The lens surface 6d is formed of a part of a spherical surface as shown in FIG. The center of curvature 6e of the lens surface 6d is located at a position displaced in the radial direction from the center axis 2a of the case 2 and at a position displaced in the same direction as the displacement of the photo IC 4. The curvature radius R of the lens surface 6d is 7.5 mm, which is larger than the inner diameter of the case 2. The focal point F of the lens 6 is disposed in the vicinity of the light receiving portion 4a of the photo IC 4, and the distance from the lens surface 6d to the focal point F is about 15 mm.

  As shown in FIG. 5, the curvature radius R of the lens 6 and the distance from the lens surface 6d to the focal point F are substantially parallel to the central axis 2a of the case 2 and almost all of the light L incident on the lens 6 is a circuit. It is determined so as to be focused on the focal point F without being shielded by the substrate 3 or the like. The radius of curvature R of the lens 6 is substantially equal to or larger than the inner diameter of the case 2 and equal to or smaller than three times the inner diameter of the case 2.

  As shown in FIG. 3, the mirror 7 is disposed in the vicinity of the light receiving portion 4 a of the photo IC 4 and in contact with the rear end of the base portion 6 a of the lens 6. The mirror 7 reflects the incident light L collected at the focal point F by the lens 6 as shown in FIG. The reflected light LR is received by the light receiving part 4a of the photo IC 4 without any leakage.

[Usage]
The light receiver 1 configured as described above is used as the light receiver 1 of the transmissive photoelectric sensor 10 as shown in FIG. 6, for example. In the example shown in FIG. 6, the light receiver 1 and the projector 11 of the transmissive photoelectric sensor 10 are fixed to brackets B <b> 1 and B <b> 2 arranged on both sides of the production line on which the workpiece W is conveyed by the conveyor V. The projector 11 is a publicly known device including a light emitting element (not shown) such as an LED. The light receiver 1 is disposed so as to face the projector 11 and be coaxial with the projector 11. The cables 5 and 15 extending from the light receiver 1 and the projector 11 are connected to an external device (not shown) such as a control device for the conveyor V, for example.

  In the photoelectric sensor 10, the detection light DL is projected from the projector 11. When the detection light DL from the projector 11 becomes incident light L and is received by the light receiving portion 4a of the photo IC 4 through the lens 6 and the mirror 7 of the light receiver 1, the photo IC 4 generates a light reception signal. The light reception signal generated by the photo IC 4 is transmitted to an external device via the cable 5. The external device recognizes the presence or absence of the workpiece W according to the level of the light reception signal received via the cable 5.

[effect]
As described above, in the light receiver 1 according to the present invention, as shown in FIG. 4, the circuit board 3 on which the photo IC 4 is mounted is located near the center axis 2 a of the case 2, i. Has been placed. Therefore, if the width | variety of the circuit board 3 is the same, the light receiver 1 can make the internal diameter of the case 2 smaller than the conventional light receiver 21 shown to FIG. 7B.
At the same time, since the distance between the lower surface of the circuit board 3 and the inner wall of the case 2 is larger than that of the conventional one, the electronic components can be easily arranged on the lower surface of the circuit board 3.

  In the light receiver 1, substantially all of the light L that is parallel to the central axis 2 a of the case 2 and is incident on the lens 6 is collected at the focal point F without being blocked by the circuit board 3 or the like. It is like that. The collected light is received by the light receiving unit 4a of the photo IC 4 through the mirror 7 without any leakage. That is, according to the light receiver 1, as shown on the left side of FIG. 5, the entire lens surface 6d can be an effective surface (hatched portion), and the amount of received light can be increased. Therefore, according to the light receiver 1, a photoelectric sensor having a long operating distance can be configured while being small.

  Further, according to the light receiver 1, the light L (detection light DL) incident on the vicinity of the central axis 2a of the case 2 can be effectively received. Since the central axis 2a of the case 2 is made to coincide with the central axis of the light projector 11 disposed to face the light, the light receiver 1 can effectively receive the main part of the detection light DL from the light projector 11. Therefore, according to the light receiver 1, the object detection accuracy can be improved.

  Further, according to the light receiver 1, the rear end of the lens 6 extends to a position where it abuts on the mirror 7, that is, to the vicinity of the light receiving portion 4 a of the photo IC 4. Thereby, in the situation where the curvature radius R of the lens surface 6d is the same, the position of the focal point F can be shifted backward. Therefore, according to the light receiver 1, the incident light L can be made difficult to be shielded by the circuit board 3 or the like.

[Modification]
In the above embodiment, the resin lens is used, but the present invention is not limited to this, and a glass lens can also be used. Further, the radius of curvature of the lens surface can be appropriately selected within a range of not less than the case inner diameter and preferably not more than three times the case inner diameter.

It is a perspective view which shows an example of the light receiver of the transmission type photoelectric sensor concerning this invention. It is a perspective view which shows the state which abbreviate | omitted the case of the light receiver of FIG. It is sectional drawing which shows the light receiver of FIG. It is a front view which shows the case of the light receiver of FIG. 1, a circuit board, and photo IC. It is a figure for demonstrating the effect | action of the lens in the light receiver of FIG. It is a perspective view which shows an example of the transmission type photoelectric sensor using the light receiver of FIG. It is sectional drawing which shows the light receiver of the conventional transmission type photoelectric sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light receiver 2 Case 2a Case central axis 3 Circuit board 4 Photo IC
4a Light receiving portion 5 Cable 6 Lens 6d Lens surface 6e Center of curvature of lens surface

Claims (2)

Photo IC,
A circuit board for mounting and driving the photo IC;
A case in which the circuit board is stored so that a light receiving portion of the photo IC faces a radial direction;
A cable connected to a circuit on the circuit board and extending from one opening of the case;
A lens that is disposed in the other opening of the case and collects incident light from outside in the vicinity of the light receiving portion of the photo IC;
A mirror that is disposed near the focal point of the lens and reflects the incident light collected by the lens and causes the light receiving unit of the photo IC to receive the light; and
In a receiver of a transmission type photoelectric sensor comprising:
The circuit board is disposed in the vicinity of the central axis of the case, the light receiving portion of the photo IC is disposed at a position shifted in one radial direction from the central axis of the case, and the center of curvature of the lens surface of the lens By disposing at a position displaced in the same direction as the one radial direction from the central axis of the case, and further, by making the radius of curvature of the lens surface more than the inner diameter of the case and not more than three times the inner diameter of the case, The incident light is almost entirely received by the light receiving portion of the photo IC.
A light receiving device for a transmissive photoelectric sensor. The light receiving device for a transmissive photoelectric sensor according to claim 1, wherein the lens extends to a position where the lens contacts the mirror.

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