JPH09178551A - Reflective photosensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reflective photosensor in which the sensitivity can be regulated without using a variable resistor which may cause error in the regulation of sensitivity. SOLUTION: Since a sensitivity regulation means, i.e., an optical diaphragm unit 5, comprises a diaphragm plate 51 provided at a light projecting section 2 or a light receiving section, and regulation grooves 52, sensitivity can be regulated without using a variable resistor which may cause error in the regulation of sensitivity due to variation in the resistance caused by deterioration of resistor due to humidity or temperature, or due to fluctuation of set value caused by movement of a slider due to vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention constantly emits a beam of light from a light projecting section, and when a detection object approaches, the reflected light from the detection object is received by a light receiving section. The present invention relates to a reflective photosensor that detects the presence of an object to be detected when the level of reflected light is above a certain level.

[0002]

2. Description of the Related Art FIG. 6 shows an example of the configuration of a conventional reflective photosensor 90 of this type. The reflective photosensor 90 is composed of a light projecting section 91, a light receiving section 92 and a detecting circuit 93. The light projecting portion 91 is composed of a light emitting element 91a such as an LED and a lens 91b, and the light receiving portion 92 is composed of a light receiving element 92a such as a photodiode and a lens 92b.

Further, the detection circuit 93 is provided with a comparator 93a to which a reference voltage set by the resistors R ₁ and R ₂ is applied to _one input terminal, and a variable resistor VR is provided on the ground E side. The output from the light receiving element 92a connected to is connected to the other one input terminal of the comparator 93a.

At this time, the light projecting portion 91 and the light receiving portion 92
Are installed so that the light emitting direction and the light receiving direction are substantially in the same direction, so that no output is generated in the light receiving element 92a when the detector X is not present, and therefore, the output terminal of the comparator 93a. No output is produced at OUT.

When the detection object X appears at a distance shorter than a preset distance, the reflected light from the detection object X reaches the light receiving section 92, and an output exceeding the reference voltage is applied to the light receiving element 92a. Then, an output is generated at the output terminal OUT of the comparator 93a to which the output is applied, and the presence of the detection object X is detected.

Here, in the reflection type photosensor 90, the light amount of the light emitting element 91a and the light receiving element 92a.
Since there is a considerable individual difference in the sensitivity of, the conventional reflective photosensor 90 is provided with a variable resistor VR in the detection circuit 93, and by adjusting the resistance value of the variable resistor VR, The individual difference between the two elements 91a and 92a is corrected.

[0007]

However, the variable resistor V included in the conventional reflective photosensor 90 described above is used.
Since R has relatively low durability against temperature, humidity, etc., and the resistance value that is set easily changes due to vibration, etc., the reflection type photo sensor 90 is installed in, for example, an outdoor vending machine. For example, due to deterioration, fluctuation, etc. of the variable resistor VR when it is attached to equipment that is subject to severe temperature changes, high humidity, and severe vibration,
The entire reflection type photo sensor 90 deteriorates in performance in a relatively short time and impairs reliability, and it has been a problem to solve this problem.

[0008]

The present invention is, as a concrete means for solving the above-mentioned conventional problems, a light projecting portion including a light emitting element and a lens, and a light receiving portion including a light receiving element and a lens. And a detection circuit for determining the presence / absence of a detection object from the output of the light receiving unit, and the sensitivity adjustment means for correcting individual differences between the light emitting element and the light receiving element is provided. The means solves the problem by providing a reflection type photosensor characterized in that the means is an optical diaphragm device provided on either one of the light projecting portion and the light receiving portion.

[0009]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. Reference numeral 1 in FIG. 1 is a reflection type photosensor according to the present invention. The reflection type photosensor 1 includes a light projecting portion 2 including a light emitting element 2a such as an LED and a lens 2b, and a light receiving element 3a such as a photodiode.
And a lens 3b, and a light receiving portion 3 and a comparator 4a.
It is the same as that of the conventional example in that it is configured with the detection circuit 4 including the.

Here, in the present invention, as a sensitivity adjusting means for correcting individual differences between the light emitting element 2a and the light receiving element 3a, an optical diaphragm device 5 is provided in either the light projecting section 2 or the light receiving section 3. It is provided. It should be noted that the above-described optical diaphragm device 5 has exactly the same operation and effect regardless of whether it is provided in the light projecting portion 2 or the light receiving portion 3. Therefore, in this embodiment, the example provided in the light projecting portion 2 is used. I will explain.

Further, since the light projecting section 2 is provided with the optical diaphragm device 5 as a sensitivity adjusting means for correcting the individual difference between the light emitting element 2a and the light receiving element 3a, in the detection circuit 4, The variable resistor VR which is conventionally provided for the purpose of correcting the individual difference is not adopted, and the light receiving element 3a is connected to the ground E by the resistor R ₃ (see also FIG. 4 of the conventional example). I want to be).

FIG. 2 shows the light projecting section 2, in which the light emitting element 2a and the lens 2b are attached to a case 2c formed of, for example, resin with a predetermined gap. ing. In the present invention, the optical diaphragm device 5 is provided in the gap between the light emitting element 2a and the lens 2b. Specifically, the diaphragm plate 51 having the opening 51a is provided between the light emitting element 2a and the lens 2b. The adjustment is performed by moving in parallel to the optical axis Z direction between them.

The diaphragm plate 51 is formed in a shape that shields the inner diameter of the case 2c in the direction orthogonal to the optical axis Z. If the inner diameter is square, the diaphragm plate is formed. 51b is also formed as a plate having a substantially square outer shape. Then, the center of the optical axis Z is kept constant, and for example, the opening 51 having a hole diameter that is substantially the same as the outer shape of the light emitting element 2a.
a is provided.

At this time, the outer shape of the diaphragm plate 51 is appropriately formed, for example, in the left-right direction to be larger than the inner diameter of the case 2c, and the light-emitting element 2a and the lens 2b on the wall surfaces on the left and right of the inner diameter of the case 2c. A plurality of adjustment grooves 52 are provided symmetrically in the space between them in the direction orthogonal to the optical axis Z, and the diaphragm plate 51 is attached to the case 2c by being dropped into the adjustment grooves 52.

Therefore, if the adjusting grooves 52 are provided at ten places, the diaphragm plate 51 is used as the light emitting element 2.
It can be adjusted to any of 10 positions between a and the lens 2b. It should be noted that the diaphragm plate 51 is orthogonal to the optical axis Z and the opening portion 51a is attached at any position.
The center of the optical axis coincides with the optical axis Z.

FIG. 3 shows the optical diaphragm device 5 having the above structure.
The operation of the diaphragm plate 51 will be described below.
In the state of being installed at the position P1 closest to the a side, the aperture 51a provided in the diaphragm plate 51 has the light emitting element 2a.
The light emitted from the light emitting element 2a is not blocked by the opening 51a and is substantially the same as the outer diameter of the lens 2
It reaches the entire surface of b.

When the diaphragm plate 51 is installed at the position P2 closest to the lens 2b side, the aperture of the lens 2b is blocked by the opening 51a.
When the ratio of a to the lens aperture is 1: 2, the light quantity is attenuated to 1/4. Then, the position P1
In the middle between the position P2 and the position P2, a damping ratio intermediate between the two is obtained.

Therefore, when the sensitivity of the reflection type photosensor 1 is set, for example, a reflector having a slightly higher reflectance than the detection limit and a reflector having a slightly lower reflectance are prepared. The diaphragm plate 51 may be set in the adjustment groove 52 at a position where detection is performed when one of the reflectors is installed in front of the light projecting unit 2 and the light receiving unit 3 and is not detected by the other reflector. .

At this time, the opening 51a of the diaphragm plate 51
Moves with the center thereof aligned with the optical axis Z.
(Or, the projection direction (light receiving direction) of the light receiving unit 3) is not changed at all.

Therefore, in the reflection type photosensor 1 of the present invention, since the adjusting groove 52 can be formed at the same time when the case 2c is formed, there is no cost for providing it and the diaphragm plate can be easily formed by, for example, press working. Only by adding 51, the sensitivity can be adjusted without using the variable resistor VR.

At this time, the diaphragm plate 51 has an adjusting groove 52.
Since it is securely held by, the adjustment does not change even when vibration etc. is applied, and
Durability can be made high by appropriately selecting the material forming the diaphragm plate 51 or the treatment,
It is possible to prevent deterioration due to temperature and humidity.

4 and 5 show another embodiment. In the previous embodiment, the diaphragm plate 51 was formed so as to move in parallel with the optical axis Z, but the present invention limits this. However, the diaphragm plate 53 is provided with a rotating shaft 53a at one end as shown in FIG. 4, and the diaphragm plate 53 is rotated like a sliding door around the rotating shaft 53a as a center of rotation, so that the light emitting element 2a The adjustment may be performed by gradually blocking the optical path between the lens 2b and the lens 2b.

In this case, the rotating shaft 53 is provided in the case 2c.
A plurality of adjustment holes 54 are provided on an arc centered on a, and a projection 53b provided at an end portion of the diaphragm plate 53 on the opposite side of the rotation shaft 53a is inserted into any one of the adjustment holes 54, so that the optical path The amount of light may be adjusted by changing the amount of penetration.

Further, at this time, the shape of the shielding portion 53c, which is a portion which shields the optical path of the diaphragm plate 53, is set to project in a triangular shape as shown in FIG. 5, for example, and a large amount of light is emitted from the light emitting element 2a. It is possible to improve the shielding efficiency by mainly shielding the vicinity of the optical axis Z.

[0025]

As described above, according to the present invention, the sensitivity adjusting means is the optical diaphragm device provided in either the light projecting portion or the light receiving portion. As a result, the sensitivity adjustment is likely to change due to the deterioration of the resistance value, or the sensitivity adjustment is likely to change due to the movement of the slider due to vibration, which may cause the sensitivity adjustment to change. It is extremely effective in improving the reliability of this type of reflective photosensor.

Further, the optical diaphragm device is configured such that the diaphragm plate provided with the opening portion of a predetermined diameter is movable in the optical axis direction between the lens and any element, Since only the diaphragm plate may be used as a component for adjusting the sensitivity, it can be implemented at a low cost and has an excellent effect on cost reduction.

[Brief description of the drawings]

FIG. 1 is a schematic wiring diagram showing an embodiment of a reflective photosensor according to the present invention.

FIG. 2 is a perspective view showing a main part of the same embodiment.

FIG. 3 is an explanatory diagram showing an operation of the optical diaphragm device.

FIG. 4 is a plan view showing another embodiment of the reflection type photosensor according to the present invention as the main part.

FIG. 5 is a plan view showing a diaphragm plate in another embodiment.

FIG. 6 is a schematic wiring diagram showing a conventional example.

[Explanation of symbols]

 1 ... Reflective photosensor 2 ... Projector 2a ... Light emitting element 2b ... Lens 2c ... Case 3 ... Light receiving section 3a ... Light receiving element 3a ... Lens 4 ... Detection circuit 5 ... Optical diaphragm Device 51, 53 ... diaphragm plate 52 ... adjustment groove 53 ... adjustment hole Z ... optical axis

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication H03K 17/78 G01S 17/02 A G01V 9/04 A

Claims (2)

[Claims] 1. A light emitting section comprising a light emitting element and a lens, a light receiving section comprising a light receiving element and a lens, and a detection circuit for determining the presence or absence of a detection object from the output of the light receiving section. In a reflection type photosensor provided with sensitivity adjusting means for correcting individual differences between an element and a light receiving element, the sensitivity adjusting means is an optical diaphragm device provided in either one of the light projecting section and the light receiving section. A reflection type photo sensor characterized by being present. 2. The optical diaphragm device is configured such that a diaphragm plate provided with an opening having a predetermined diameter is movable in the optical axis direction between the lens and any one of the elements. The reflective photosensor according to claim 1, which is characterized in that.