JP4999595B2 - Reflective photo sensor - Google Patents

Description

  The present invention is a reflective photosensor, particularly a reflective photosensor in which the light emitting and receiving surfaces of a light emitting element and a light receiving element are arranged in a direction perpendicular to the moving direction of the detected object, and the amount of movement of the detected object with a simple configuration. And for detecting a moving position.

  As a reflection type photosensor, there is a photo reflector or the like. This reflection type photosensor is a photodetector that detects the presence or absence of an object, the position and movement amount of an object in a non-contact manner, for example, an audio tape of a video device or the like. It is used for detection of a start position and end position, detection of paper in a copying machine and printer, detection of a position of a pickup unit in an optical drive device such as a CD and DVD, and detection of a lens position for zooming or focusing operation of an autofocus camera.

  7A and 7B show a configuration example of a conventional photo reflector, and FIG. 7A detects an object moving in the vertical direction of the photo reflector (the following Patent Document 1). ). This photoreflector is formed on an insulating substrate 1, a window portion 3 disposed on the insulating substrate 1 and surrounding the outer periphery and having an intermediate light shielding wall portion 2, and one recess formed by the window portion 3 and the intermediate light shielding wall portion 2. It has the light emitting element 4 arrange | positioned and the light receiving element 5 arrange | positioned in the other recessed part.

  In such a photoreflector of FIG. 7A, when the detected object 6 moving in the vertical (arrow U) direction is at the position of the chain line, the light output from the light emitting element 4 is the intermediate light shielding wall 2. However, when it is at the position of the solid line, the light output from the light emitting element 4 reaches the light receiving element 5, and depending on the detection state of this light receiving element 5, the object 6 at a predetermined position is detected. Presence is detected.

  FIG. 7 (B) is for detecting an object that moves in the arrangement direction of the light-emitting elements and the light-receiving elements of the photoreflector (the following Patent Document 2). The photoreflector is mounted on the mounting board 8 and the mounting board 8. The photo reflector 9 is provided, and the slit mechanism 11 is formed above the photo reflector 9 and has a slit 10 formed therein.

  In such a photoreflector in FIG. 7B, when the detected object 12 moving in the horizontal direction indicated by arrow F reaches a position above the photoreflector 9, it is irradiated from the light emitting element in the photoreflector 9. The detected light passes through the slit 10 and strikes the detected object 12, and the reflected light passes through the slit 10 and is detected by the light receiving element, whereby the presence of the detected object 12 is detected.

Conventionally, there are the following Patent Documents 3 and 4 for detecting the position of a camera lens using a photoreflector. These Documents 3 and 4 include a cylindrical outer peripheral surface such as a cam ring of an optical system. Rotating position of the optical system (lens) by arranging a pattern (bright / dark pattern) member that changes the amount of reflected light, consisting of a high reflection part and a light shielding part, and detecting the amount of reflected light from the pattern member with a photo reflector (Zoom position) and the like are detected.
JP 2001-156325 A JP 2006-173306 A JP-A-5-45179 JP 2002-357762 A

  However, the conventional photo reflectors shown in FIGS. 7A and 7B can only detect the presence or absence of a detection object that moves in the vertical direction or the horizontal direction, and the position and amount of movement of the detection object that moves. Cannot be detected.

  On the other hand, as disclosed in the above Patent Documents 3 and 4, in order to detect the rotational position of the optical lens using a photo reflector, a high-precision light and dark pattern member composed of a high reflection portion and a light shielding portion is manufactured. It is necessary to provide this on the object to be detected side, and there is a problem that the configuration becomes complicated.

  The present invention has been made in view of the above problems, and its purpose is to provide a simple configuration using a light emitting element and a light receiving element, and without providing a light / dark pattern member on the object to be detected side. An object of the present invention is to provide a reflection type photosensor that can detect a movement amount and a movement position satisfactorily.

In order to achieve the above object, in the invention according to claim 1, the light projecting and receiving surfaces of the light emitting unit and the light receiving unit are arranged in a direction perpendicular to the moving direction of the detected object that moves parallel to the light projecting and receiving surface. In the reflection type photosensor that receives the reflected light from the detected object based on the output light of the light emitting unit by the light receiving unit, the detection output of the light receiving unit corresponds to the amount of movement of the detected object. The light receiving region is provided such that the area per unit length increases toward the both ends from the center in the moving direction of the detected object so as to change linearly.
According to a second aspect of the present invention, the light receiving region of the light receiving portion is formed by partially covering the active portion (the original light receiving surface of the active layer or the like) with a reflector (aluminum film, metal alloy film, reflective tape, or the like). It is formed.

  According to the configuration of the present invention, the light receiving portion (light receiving element) is provided with a light receiving region having an area that increases from the center portion toward both ends of the moving direction of the object to be detected, and is arranged in the vertical direction in the sensor. When the object to be detected moves from the left side to the right side above the light emitting part (light emitting element) and the light receiving part, the reflected light from the object to be detected first enters the left end of the large area of the light receiving area, and the incident area is , It becomes smaller as it moves, and then gradually increases toward the right end. As a result, the light receiving unit detects the amount of light that linearly changes in response to the movement of the detected object, and the amount or position of movement of the detected object can be detected based on the detected light quantity. That is, in the light receiving region having the same width, the amount of light incident on the central portion increases, so that the linearly changing range is increased by reducing the light receiving region at the central portion.

  According to the configuration of the second aspect, the reflected light from the object to be detected that falls on the region other than the light receiving region on the upper surface of the light receiving unit is further reflected, thereby increasing the amount of light received in the light receiving region and improving the sensitivity. Can do.

According to the reflection type photosensor of the present invention, a configuration in which the relationship between the amount of movement of the detected object and the change in the sensor output is linear can be expanded to a practical level by designing the light receiving unit, and the configuration is simple. Thus, there is an effect that the moving position of the object to be detected can be detected well. Further, unlike a position detection sensor for an optical lens used in a conventional camera, it is not necessary to provide a light / dark pattern member on the detected object side.
According to the second aspect of the present invention, it is possible to form a light receiving region having an area that increases from the central portion toward both ends only by covering the active portion of the light receiving portion with a reflector (for example, forming an aluminum film). There is an advantage that the manufacture of the sensor is extremely easy.

  FIG. 1 shows a configuration of a reflective photosensor (photoreflector) according to an embodiment of the present invention. FIG. 1B is a cross-sectional view taken along line bb in FIG. 1A, and FIG. It is a figure by the side of the light-receiving surface. As shown in FIGS. 1A and 1B, in the reflection type photosensor of the embodiment, bonding patterns 17a to 17d are formed on an insulating substrate 16, and a light emitting element as a light emitting portion is formed on the bonding pattern 17a. A light receiving element (for example, phototransistor) 20 as a light receiving portion is die-bonded to (for example, a light emitting diode) 18 and a bonding pattern 17b, and the light emitting element 18 and the light receiving element 20 have the same length in the moving direction H of the object to be detected. The gold wires 21 are formed and connected to the positions of the bonding patterns 17c and 17d. On the back surface of the insulating substrate 16, back surface electrodes 22a to 22d (22a and 22b are not shown) connected to the bonding patterns 17a to 17d, respectively.

  Further, an outer peripheral light shielding wall 24 having a predetermined height is formed so as to surround the light emitting element 18 and the light receiving element 20, and an intermediate light shielding wall 25 is provided between the light emitting element 18 and the light receiving element 20. The upper space of the light emitting element 18 and the light receiving element 20 provided and surrounded by the outer peripheral light shielding wall 24 and the intermediate light shielding wall 25 is sealed with a resin 26 that transmits light. The light emitting / receiving surfaces of the light emitting element 18 and the light receiving element 20 are parallel to the moving direction H of the object to be detected, and are arranged along a direction perpendicular to the moving direction H.

As shown in FIG. 1C, in the light receiving element 20, the light receiving region 20E whose area per unit length (H direction) increases from the center of the moving direction H of the detection object toward the left and right ends. ₁ is set. That is, the lower side of the active layer (original light receiving surface) of the light receiving element 20 is covered with a semi-elliptical light shielding reflection film 28 made of an aluminum film, a metal alloy film, or the like (or a light shielding reflection tape is attached). receiving surface (horizontal rectangular active layer) is partitioned by a semi-elliptical line, gradually reduced toward the center light receiving area from the left end, and gradually increase from the center to the right light-receiving region 20E ₁ Is formed.

  The reflection type photosensor according to the embodiment has the above-described configuration, and the light detection action of the reflection type photosensor will be described with reference to FIGS. FIG. 2A shows the inside of the sensor of FIG. 1 as viewed from the light emitting element 18 side in a direction perpendicular to the moving direction H of the detected object. The detected object 30 moves from the left side to the right side. 2B is a view of the inside of the sensor viewed from the same direction as FIG. 1B. The light output from the light emitting element 18 is reflected by the moving object 30 to be moved in the moving direction H. FIG. It is guided to the light receiving element 20 side existing in the vertical direction. Note that light that directly enters the light receiving element 20 from the light emitting element 18 is shielded by the intermediate light shielding wall 25.

As shown in FIG. 3A, when the object 30 first reaches the position P1 so as to cover the light emitting element 18 and the light receiving element 20, the light L1 output from the left end of the light emitting element 18 is obtained. Is reflected by the object to be detected 30 and begins to enter the light receiving element 20 (light receiving region 20E ₁ ). Here, the reflected light L 2 and the like output from other than the left end portion of the light emitting element 18 does not enter the light receiving element 20. As shown in FIG. 3B, as the detected object 30 reaches the position P2, the reflected light similar to L1 gradually increases and the reflected light L3 having a different reflection angle also increases. As the detected object 30 reaches the position P3, the reflected light L1 and L3 gradually increase, and the reflected light L4 having different reflection angles also increases, so that the amount of movement of the detected object 30 increases. The light reaching the upper surface of the light receiving element 20 increases.

Then, in the embodiment, change as the area of the light receiving region 20E ₁ of the light receiving element 20 is directed from the center to the left and right ends, since the widened from the light receiving element 20, linearly according to the amount of movement of the object to be detected 30 Detection output is obtained. That is, as shown in FIG. 2A, when the amount of movement of the object to be detected 30 increases, the reflection from the region of the light emitting element 18 that is not covered with the object to be detected 30 like the reflected light L5. As understood from the increase in light, etc., there is a phenomenon that the reflected light from the detection object 30 is collected at the center of the light receiving element 20, and the incident light increases toward the center. Therefore, in the embodiment, as shown in FIG. 1 (C), the center of the light receiving region 20E ₁ is by a shape recessed in a semi-elliptical shape, as toward the center, to reduce the number becomes incident light To get linear characteristics.

FIG. 4 shows a graph in which the output of the photosensor with respect to the amount of movement of the object to be detected is represented by the relative outputs of the example (C ₁₀₀ ) and the conventional example (C ₂₀₀ ). In the conventional example, the characteristic C ₂₀₀ is shown. as shown in, the moving range of the linear characteristic is obtained while was .DELTA.X1, in the present embodiment, as shown in characteristic C _100, the moving range of the linear characteristic is obtained and practical ΔX2 It spreads greatly to such a range.

FIG. 5 shows another example of the light receiving region formed in the light receiving element 20 of the embodiment. FIG. 5A is a semi-elliptical shape that forms a partition line as compared to FIG. it is obtained by forming a light-receiving region 20E ₂ by the light shielding reflective film 31 that short major axis, as in the partition lines 50, may be most light receiving region without a region of the heart. 5B shows a light receiving region 20E _{3 in} which the active layer is partitioned by a light-shielding reflective film 32 having a trapezoidal line (or a trapezoidal line like the partitioning line 51), and FIG. 5C shows a triangular line (or partitioning). a light receiving region 20E ₄ triangle line) were partitions the active layer by the light-shielding reflective film 33 having such as lines 52, as directed from the center to both ends, in which as the area per unit length increases. FIG. 5 (D) placing the two light-shielding reflective film 34 having a semi-elliptical line vertically is obtained by the light-receiving region 20E ₅ area spreading like a horn toward both end from the center, as with this Two reflective films having the shapes shown in FIGS. 5B and 5C may be arranged one above the other. Such light receiving regions 20E _{2 to} 20E ₅ can also obtain linear characteristics in light detection.

FIG. 6 shows another configuration example of the light-emitting element of the embodiment, which is obtained by reducing the light emission amount at the center of the light-emitting element in the moving direction H of the object to be detected compared to both ends. . 6A, the central portion of a light emitting element (active layer) 35 having the same configuration as that in FIG. 1A is covered with a rectangular aluminum light shielding film (or other light shielding body) 36, and a light emitting region 35G ₁ which was provided, FIG. 6 (B) a central portion of the light emitting element 35, covered with aluminum light shielding film 38 disposed the to match the vertices of a triangle and inverted triangle, it is provided with a light emitting region 35G ₂ .

According to the light emitting areas 35G ₁ and 35G ₂ of the light emitting element 35, the light emission amount at the center in the moving direction H of the detection object is small, and thus the light receiving areas having the light receiving areas 20E _{1 to} E ₅ having various shapes described above. By combining with the element 20, the range (ΔX) in which the linear characteristic can be obtained can be expanded or the linearity thereof can be improved.

In the above embodiment, an example is shown in which the structure is applied to the structure of a surface mount type photo reflector. However, this surface mount type has no outer light shielding wall 24 (intermediate light shielding wall 25 is required), and other types such as a lead pin type. The present invention can be applied to a photoreflector having the following structure.
Moreover, although the example which used the phototransistor for the light receiving element 20 was shown in the Example, you may apply a photodiode and photo IC as a light receiving element.
Furthermore, although the light emitting element 18 of the embodiment uses one of the same length as the light receiving element 20 in the direction H, a plurality of light emitting portions in which individual light emitting elements are arranged at the left and right ends or a plurality of small size light emitting elements. The same effect can be obtained as the arranged light emitting portion.

1A and 1B show a configuration of a reflective photosensor according to an embodiment of the present invention, in which FIG. 1A is a top view, FIG. 1B is a cross-sectional view along line bb in FIG. 1A, and FIG. It is a figure of the surface side. FIG. 2A shows light reaching the light receiving element from the light emitting element of the reflective photosensor of the embodiment, FIG. 1A is a view of the inside of the sensor as viewed from the light emitting element toward the light receiving element, and FIG. It is the figure seen from the side surface side of an element and a light receiving element. It is a figure for demonstrating the light detection effect | action at the time of detecting the movement amount etc. of a to-be-detected object with the reflection type photosensor of an Example. The output of the photosensor with respect to the amount of movement of the object to be detected in the example, is a graph showing a relative output of the conventional example as in Example _{(C 100) (C 200)} . It is a top view which shows the other example of the light reception area | region in the light receiving element of an Example. It is a top view which shows the other example which changed the light emission area | region in the light emitting element of an Example. It is a figure which shows two structural examples of the conventional photo reflector.

Explanation of symbols

1,16 ... insulating substrate 4,18,35 ... light emitting element,
5, 20 ... light receiving element 6, 12, 30 ... object to be detected,
17a to 17d: bonding pattern,
20E _{1 to} 20E ₅ ... Light receiving region,
24 ... outer peripheral light shielding wall, 25 ... intermediate light shielding wall,
28, 31, 32, 33, 34 ... light-shielding reflective film,
36, 38... Light shielding film, 35G ₁ , 35G ₂ .

Claims (2)

The light projecting and receiving surfaces of the light emitting unit and the light receiving unit are arranged in a direction perpendicular to the moving direction of the detected object that moves parallel to the light projecting and receiving surface, and the reflection from the detected object based on the output light of the light emitting unit. In a reflective photosensor that receives light at the light receiving unit,
In the light receiving unit, the detection output per unit length increases from the center of the moving direction of the detected object toward both ends so that the detection output changes linearly according to the moving amount of the detected object. A reflection type photosensor characterized in that a light receiving region having a large area is provided.   2. The reflective photosensor according to claim 1, wherein the light receiving region of the light receiving portion is formed by partially covering the active portion with a reflector.

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