JP2001156325A - Photo reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of the analog-like detection of distance or the like instead of digital-like detection for detecting the presence or absence of a measurement target regarding a photo reflector with a light-emitting element and a photo detector. SOLUTION: In a photo reflector 10 having two pairs of electrodes 2, 3 and 4, 5 being formed on an insulation substrate 1, a light-emitting device 6 that is mounted on a pair of electrodes out of the two pairs of electrodes and a photo detector 7 that is mounted on the other pair of electrodes, and an intermediate light-shielding member 8c for shielding the area between the light-emitting device 6 and the photo detector 7, the light-emitting device 6 and the photo detector 7 are arranged in contact with or close to the intermediate light- shielding member 8c by putting to one side. With the arrangement, the distance between the light-emitting device 6 and the photo detector 7, and the measurement target is reduced, and the detection output of the photo detector 7 is improved, thus achieving analog-like detection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreflector for detecting the presence or absence of an object or the position of the object.

[0002]

2. Description of the Related Art A photoreflector is an optical sensor for detecting the presence or absence of an object and the position of the object without contact, and is used for controlling the rotation of a motor and the like, and detecting the position and edge of paper and film. The general configuration and principle will be described. The light-emitting element includes a light-shielded light-emitting element and a light-receiving element. Light emitted from the light-emitting element is reflected on an object to be detected, and the reflected light is detected by the light-receiving element. by this,
The output on the light receiving element side changes according to the presence or absence and position of an object near the photo reflector, and this is used as a detection signal.

FIG. 6 shows an example of a conventionally known photoreflector. In FIG. 6, reference numeral 101 denotes an insulating substrate;
Reference numeral 06 denotes a light-emitting element such as a light-emitting diode (hereinafter, referred to as an LED), which is die-bonded to one of a pair of electrodes (not shown) provided on the insulating substrate 101, and to the other electrode by a gold wire or the like. Wire bonded. 7
Is a light receiving element composed of a phototransistor or the like, which is die-bonded to one electrode of another pair of electrodes (not shown), and wire-bonded to the other electrode by a gold wire or the like. Reference numeral 108 denotes a light-shielding frame made of plastic or the like having a light-shielding property and mounted on the insulating substrate 101 so as to surround the light-emitting element 106 and the light-receiving element 107. The light-shielding frame 108 regulates the light-emitting and light-receiving directions of the light-emitting element 106 and the light-receiving element 107. .
The light-shielding frame 108 includes the light-emitting element 106 and the light-receiving element 107.
Windows 108 provided in the light emission and light reception directions of
a, 108b, and an intermediate light-shielding wall portion 108c that shields light between the light-emitting element 106 and the light-receiving element 107. 109,
Reference numeral 110 denotes a sealing member made of a translucent resin, which covers the light emitting element 106 and the light receiving element 107 and seals them.

Reference numeral 113 denotes an object to be measured. As shown in FIG. 6, when the measurement target 113 is at the position indicated by the solid line, the light emission of the light emitting element 106 is refracted at the interface 109a between the sealing member 109 and air and reaches the measurement target 113,
The light is reflected by the surface, the reflected light is refracted at the interface 110a of the sealing member 110, enters the light receiving element 107, and outputs a detection signal to detect the presence of the measurement target 113.

FIG. 7 shows a modification of the photoreflector shown in FIG. 6, in which the light-shielding film 10 is formed by leaving openings on the surfaces of sealing members 109 and 110 instead of the light-shielding frame 108.
9b and 109c and 110b and 110c are formed to simplify the configuration. Here, the light shielding films 109c and 11
Reference numeral 0c denotes an intermediate light shielding film, which is an intermediate light shielding wall 108c in FIG.
The light-shielding films 109b and 110b are light-shielding and reflecting films for the windows and serve to reflect the internal light as well as the windows 108a and 108b in FIG. 1, respectively. Although slopes are provided in the sealing members 109 and 110 to reduce the area of the opening so as to be suitable for fine detection, and the reflection of the slopes on the light shielding films 109b and 110b increases the light use efficiency. The basic principle of detection is the same as that shown in FIG.

In the photoreflectors shown in FIGS. 6 and 7, when the object to be measured 113 comes close to, for example, a position shown by a broken line, the incident light from the light emitting element 106 is reflected and the light receiving element 107 is reflected. 6, the incident light from the light emitting element 106 is applied to the measurement object 113 almost directly above the intermediate light-shielding wall portion 108 c in FIG.
It is necessary that the light is incident on the intermediate light-shielding films 109c and 110c in FIG. That is, when the light is incident on the light receiving element side from the portion immediately above, the reflected light is transmitted to the intermediate light shielding wall 1.
08c or the like, and cannot reach the light receiving element 107.

In order to make the light incident on the portion directly above, the interface 109 a of the sealing member 109 in the light emitted from the light emitting element 106 is used.
It is necessary to use one having a sufficiently large incident angle θ with respect to. However, even if the incident angle θ is increased, light reaching the interface 109a of the sealing member 109 at an angle equal to or greater than the critical angle θc determined by the material of the sealing member 109 is totally reflected. It will not be in the state. For this reason, when the measurement object 113 approaches the photo reflector, the presence or absence of the object cannot be detected.

FIG. 8 is a sectional view showing a known photoreflector in which such a disadvantage is improved. This photoreflector is not provided with a molding member such as a sealing member (109, 110), and the light emitting element 106 and the light receiving element 10 are not provided.
7 is coated with thin film coating resins 106b and 107b. The inside of the light shielding frame 108 including the windows 108a and 108b and the intermediate light shielding part 108c is hollow. As shown in FIG. 8, the light projected from the light emitting element 106 is projected like a light path indicated by an arrow and reflected by the measurement target 113, so that when the light is projected outside the light shielding frame 108. There is no refraction and projection is not blocked by total internal reflection.

For this reason, it is possible to detect even the measuring object 113 existing in a very close position. In this way, even in the case of a conventional reflector, the presence or absence of the object can be detected even when the object to be measured approaches.

[0010]

However, even in the photoreflector as shown in FIG. 8 described above, if the analog amount of the distance or the direction angle of the object to be measured is to be accurately detected, the following problem arises. is there. FIG.
As shown by the arrow of, of the light emitted from the light emitting element 106, the light that actually contributes to the detection of the light receiving element 107 is light that is incident immediately above the intermediate light shielding portion 108c, It is a light beam deviated from the normal direction 106a by a considerably large angle (reflected light of a light beam having an angle close to the normal direction is blocked by the intermediate light shield 108c and
It is difficult to reach 107. ). Here, the solid angle of the effective reflecting surface with respect to the light emitting element 106 decreases as the measurement object 113 approaches and the direction of the light beam incident on the effective reflecting surface deviates from the normal direction 106a. The amount of light decreases. Therefore, even if this reflected light is incident on the light receiving element 107, the amount of incident light is not sufficient, and even if digital detection for detecting the presence or absence of an object to be measured can be performed, but analog amount such as distance can be detected. Does not reach.

That is, in digital detection,
It is sufficient that the signal output of the light receiving element 107 reaches a predetermined value exceeding the S / N ratio. However, in analog detection, simply reaching this predetermined value is not sufficient, and the detection of the analog amount is not sufficient. This is because, in order to identify the significant difference, a signal output several times as large as this is required. In this sense,
As shown in FIG. 8, at least when the measurement target 113 approaches a certain distance, it becomes impossible to detect the analog amount. Therefore, even when the measurement target 113 is separated to a certain extent, the analog amount can be detected at a distance. It will not be easy to increase the reliability of the system.

The present invention relates to a photoreflector comprising a light-emitting element and a light-receiving element, wherein the light-reflection element detects the reflected light of the light-emitting element reflected by the object to be measured. Is what you do.
An object of the present invention is to solve the above problem and provide a photoreflector capable of detecting not only a digital quantity indicating the presence or absence of an object to be measured but also an analog quantity such as its distance and angle with sufficient reliability. It is.

[0013]

As a first means for solving the above-mentioned problems, the present invention provides two pairs of electrodes formed on an insulating substrate, and one pair of the two pairs of electrodes. In a photoreflector having a light emitting element mounted on an electrode, a light receiving element mounted on another pair of electrodes, and an intermediate light shielding member for shielding light between the light emitting element and the light receiving element, The light emitting element and the light receiving element are arranged in contact with or in close proximity to each other.

According to a second aspect of the present invention to solve the above-mentioned problems, the present invention is characterized in that, in the first aspect, the light emitting element and the light receiving element are mounted on the corresponding pair of electrodes by the light emitting surface of the light emitting element and The light receiving surface of the light receiving element is mounted on the light emitting surface and the electrode of the light receiving surface of the light receiving element without forming a bonding ball by wire bonding of a reverse bonding method.

According to a third aspect of the present invention, there is provided the light emitting device according to the first or second aspect, wherein the intermediate light-shielding member has a plate shape, and And is coupled to a light-shielding mold frame which surrounds the periphery and is open at the top.

According to a fourth aspect of the present invention, there is provided the light emitting device according to the first or second aspect, wherein the intermediate light-shielding member has a plate shape, and is provided around the light emitting element and the light receiving element. And is integrally formed with a light-shielding mold frame which is open at the top.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problems, the present invention provides a method according to any one of the first to fourth means, wherein the light-emitting element and the light-receiving element are formed of a translucent resin on the outer periphery. It is characterized in that a thin-film-shaped coating is applied, and the inside of the light-shielding mold frame is a hollow portion, and the hollow portion is filled with air.

According to a sixth aspect of the present invention, in order to solve the above-mentioned problems, in any one of the first to fifth means, the light emitting element is an LED, and the light receiving element is a phototransistor or a phototransistor. It is a photodiode.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a configuration of the photoreflector according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line AA of FIG. As shown in the figure, in a photo reflector 10 according to the present embodiment, a light emitting element 6 such as an LED and a light receiving element such as a phototransistor or a photodiode are provided on each of a pair of electrodes 2, 3 and 4, 5 on an insulating substrate 1. The elements 7 are bonded so as to be juxtaposed as a pair. That is, the light emitting element 6 is die-bonded on the electrode 2 and wire-bonded to the electrode 3 by a bonding wire 20 such as a gold wire. In this wire bonding, the first side of the bonding wire 20 is bonded to the electrode 3 by ball bonding, and the second side is bonded to the upper surface (light emitting surface) of the light emitting element 6 by wedge bonding, so-called reverse bonding. As a result, the distance that the bonding wire 20 projects upward from the upper surface of the light emitting element 6 is shorter than in the case of normal bonding.

The light receiving element 7 is bonded to the electrode 4 by die bonding, and the electrode 5 is reversely bonded to the electrode 5 by the same bonding wire 20 as described above. Light emitting element 6
And the outer periphery of the light receiving element 7 is thin film coat resin 6b and 7
b, so that the light emitting element 6
And the light receiving element 7 is protected. Reference numeral 8 denotes a light-shielding frame made of a light-shielding plastic or the like mounted on the insulating substrate 1 so as to surround the light-emitting element 6 and the light-receiving element 7.
And the direction of light emission and light reception of the light receiving element 7.
The light-shielding frame 8 includes windows 8 a and 8 b provided in the light-emitting and light-receiving directions of the light-emitting element 6 and the light-receiving element 7, and an intermediate light-shielding wall 8 that shields light between the light-emitting element 6 and the light-receiving element 7.
c.

With the intermediate light-shielding wall 8c interposed therebetween,
The light emitting element 6 is located at a position where the light emitting element 6 contacts or substantially contacts both sides thereof.
The light receiving element 7 is fixed to the electrode by the above-mentioned die bonding. The inside of the light shielding frame 8 is not filled with a sealing member or the like, and is in a hollow state like the photo reflector shown in FIG.

In order to manufacture the photoreflector according to the present embodiment, the light shielding frame 8 is integrally formed and fixed on the insulating substrate 1 by molding a light shielding resin using a molding die or the like. Then, the light emitting element 6 is placed at a predetermined position.
And the light receiving element 7 are arranged, and by the above-described bonding, fixing to the insulating substrate and electrical connection to the electrodes are performed. After that, a thin film coating resin 6b is formed on the outer periphery of the light emitting element 6 and the light receiving element 7 by potting or spin coating.
And 7b. On this occasion,
As in the case of the known technique, it is also possible to take a large number of pieces using a common substrate.

The operation of the photoreflector in the above configuration will be described below. Now, in a state where a predetermined voltage is applied between the electrode 2 and the electrode 3 and the light emitting element 6 emits light, FIG.
As shown in the figure, when the measuring object 13 is located in a close position as shown by a solid line, the effective reflection area S1 immediately above the intermediate light-shielding wall 8c is considered, and the effective reflection area S1
When the light incident on the light receiving element 7 is reflected and incident on the light receiving element 7,
As a representative one of the reflected lights, attention is paid to the light flux s1 incident on the center of the light receiving element 7.

The direction of light traveling from the light emitting element 6 toward the effective reflection area S1 is the normal 6a of the light emitting surface (upper surface) of the light emitting element 6.
Is shifted from the direction by a considerably large angle. Here, as the direction of the incident light beam with respect to the effective reflecting surface deviates from the normal direction 6a, the solid angle of the effective reflecting surface with respect to the light emitting element 6 decreases, and the amount of light on the reflecting surface tends to decrease. That is, the light amount of the effective reflection area S1 decreases as the effective reflection area shifts from the normal direction 6a. However, compared to the case of the conventional example shown in FIG. 8, the solid angle of the region S1 with respect to the light emitting element 6 and the solid angle of the incident light beam s1 in the light receiving element are considerably large. Therefore, the light amount in the effective reflection area, the light amount detected by the light receiving element 7 and the output level of the detection signal are greatly increased as compared with the conventional case, and can be recognized as analog amounts. Here, the reason why the solid angle becomes larger than before is that the intermediate light-shielding wall portion 8c is used.
The light-emitting element 6 and the light-receiving element are disposed in contact with the light-emitting element 6 and the protruding amount of the intermediate light-shielding wall portion 8c is also small. It depends.

Next, when the measuring object 13 is located at a position indicated by a broken line slightly away from the photoreflector, the measuring object on which the incident light from the light emitting element 6 is incident at an angle relatively close to the direction of the normal 6a. The area 13 is an effective reflection area S2. When light incident on the effective reflection area S2 from the light emitting element 6 is reflected and incident on the light receiving element 7, the light receiving element 7 is a representative one of the reflected lights. Attention is focused on the light flux s2 incident on the center of. Since the direction of light incident on the effective reflection area S2 from the light emitting element 6 is close to the direction of the normal 6a, it is advantageous in terms of solid angle, and the solid angle of the effective reflection area S2 is larger than the solid angle of the effective reflection area S1 as shown in the figure. Is also great. Therefore, the effective reflection area S2 is larger than the effective reflection area S1.
And the light quantity of the light beam s2 of the light incident on the light receiving element 7 and the signal output of the light receiving element 7 are significantly increased as compared with the case of the light beam s1. This signal output is, of course, a reliable analog quantity, and a clear significant difference from s1 is obtained.

As described above, the analog signal output by the light amount detection of the light receiving element 7 remarkably changes according to the distance of the measuring object 13 from the photo reflector 10. FIG. 3 is a diagram showing detection characteristics of the photoreflector shown in FIGS. 1 and 2. That is, when the distance from the photoreflector 10 to the measuring object 13 is x and the analog signal output of the light receiving element 7 is IA, the relationship between the distance x and the analog signal output IA is shown. As shown in FIG. 3, the output of the analog signal monotonously and significantly increases as x increases in a predetermined range of the distance x, and the distance can be measured by the photoreflector in this range. The detection sensitivity is S
Let a be the increment ΔIA of IA with respect to the increment Δx of x
Is the detection sensitivity Sa, and Sa = ΔIA / Δx, which is the slope of the output curve of the analog signal in FIG. In the case of this example, the detection sensitivity Sa is considerably high within a predetermined range of the distance x, and reliable and good distance detection can be performed. When the distance x of the object to be measured becomes a certain value or more, the light amount decreases by the length of the optical path, and as shown in FIG. 3, the analog signal output exceeds the maximum value and decreases instead. .

As described above, according to the present embodiment, not only the presence / absence of an object to be measured can be detected but also the moving distance thereof can be accurately detected in an analog manner. In the photo reflector according to the present embodiment, as described above, the length of the step between the intermediate light-shielding wall 8c and the light-emitting element 6 or the light-receiving element is kept short. In this way, even when the measurement object is very close, it is devised so that it can be detected. This is also made possible by the fact that the projection of the bonding wire 20 is kept short by the reverse bonding as described above. In the present embodiment, the accuracy of the positioning of the light emitting element 6 and the light receiving element 7 can be easily increased by contacting the intermediate light-shielding wall portion 8c. And the reliability of the product can be improved.

A modification of the photoreflector shown in FIG. 1 will be described below as another embodiment of the present invention with reference to the drawings. FIG. 4 is a perspective view showing the configuration of the photo reflector according to the present embodiment. As shown in FIG. 4, the light shielding frame 8 includes windows 8a and 8b and an intermediate light shielding plate 8d separate from the windows. FIG. 5 is a perspective view showing a state in which the photo reflector shown in FIG. 4 is being formed. As shown in FIG. 5, the intermediate light-shielding plate 8d is joined and fixed on the insulating substrate 1 in an upright state using a guide groove or the like in advance.

Then, the light-emitting element 6 and the light-receiving element 7 are positioned so as to be in contact with the upright intermediate light-shielding plate 8d, and the same light-bonding as in FIG. It is fixed to an electrode on a substrate, and is also electrically connected to the electrode. After that, the thin film coating resin is coated on the outer periphery of the light emitting element 6 and the light receiving element 7 by potting or spin coating. Next, using a molding die or the like, a light-shielding resin is used, and the light-shielding frame 8 has windows 8a and 8b.
Is connected to the intermediate light-shielding plate 8d on the insulating substrate 1,
Further, it is formed by molding so as to surround the light emitting element 6 and the light receiving element 7. At this time, as in the case of the known technique, it is also possible to take a large number of pieces by using a collective substrate.

The configuration of the photo reflector shown in FIGS. 4 and 5 is the same as that of the photo reflector shown in FIG.
It is similar to the photoreflector shown in FIG. 1 and performs the same operation. However, in the fabrication of the photoreflector of the present embodiment, the light-emitting frame 6 surrounding the light-emitting element 6 and the light-receiving element 7 is formed with the windows 8a and 8b after the bonding of the light-emitting element 6 and the light-receiving element 7 as described above. The windows 8a and 8b can be formed quite close to the light receiving element 6 and the light receiving element 7. This makes it possible to reduce the size of the device, and to easily adapt to a small measurement target.

[0031]

The present invention relates to a photoreflector comprising a light emitting element and a light receiving element, wherein the light reflected by the object to be measured is reflected by the light receiving element. A photoreflector that enables analog detection to detect changes in the distance of an object, etc., and can perform both digital detection to detect the presence or absence of an object and analog detection to detect and measure the distance etc. with high reliability. Can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a photo reflector according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a diagram showing analog detection characteristics of the photo reflector shown in FIG.

FIG. 4 is a perspective view showing a configuration of a photo reflector according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a state in the course of manufacturing the photo reflector shown in FIG. 4;

FIG. 6 is a cross-sectional view illustrating a configuration of a conventional photo reflector.

FIG. 7 is a cross-sectional view illustrating a configuration of a conventional photo reflector.

FIG. 8 is a cross-sectional view showing a configuration of a conventional photo reflector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2, 3, 4, 5 Electrode 6 Light emitting element 6b, 7b Thin film coating resin 7 Light receiving element 8 Light shielding frame 8a, 8b Window 8c Intermediate light shielding wall 8d Intermediate light shielding plate 10 Photoreflector 13 Measurement object 20 Bonding wire

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[Procedure amendment]

[Submission date] December 3, 1999 (1999.12.
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

[Title of the Invention] Photoreflector

Claims (6)

[Claims] A pair of electrodes formed on an insulating substrate;
A photo-detector having a light-emitting element mounted on one pair of electrodes of the two pairs of electrodes, a light-receiving element mounted on another pair of electrodes, and an intermediate light-shielding member for shielding light between the light-emitting element and the light-receiving element; In a reflector, the light-emitting element and the light-receiving element are arranged so as to contact or approach the intermediate light-blocking member by one-sided alignment. 2. The light emitting element and the light receiving element are mounted on the pair of electrodes corresponding to each other by mounting the light emitting surface of the light emitting element and the light receiving surface of the light receiving element by wire bonding of a reverse bonding method. 2. The photoreflector according to claim 1, wherein the light reflection is performed without forming a bonding ball on the electrode on the light receiving surface. 3. The light-shielding mold frame, wherein the intermediate light-shielding member has a plate shape and surrounds the light-emitting element and the light-receiving element and is open at the top. Item 3. The photoreflector according to Item 2. 4. The light-shielding mold frame according to claim 1, wherein the intermediate light-shielding member is plate-shaped, and is integrally formed with a light-shielding mold frame surrounding the light-emitting element and the light-receiving element and opening upward. The photoreflector according to claim 2. 5. The light-emitting element and the light-receiving element are provided with a thin-film coating made of a light-transmitting resin on the outer periphery thereof, and the light-shielding mold frame has a hollow portion, and the hollow portion is filled with air. The photoreflector according to any one of claims 1 to 4, wherein: 6. The photo reflector according to claim 1, wherein the light emitting element is an LED, and the light receiving element is a phototransistor or a photodiode.