JP2012093302A - Position detecting device using reflection type photosensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detecting device using a reflection type photosensor in which a position sensing not less than 1 mm can be favorably conducted and detection at high resolution is possible by using a simple and small-sized constitution without using a magnetic sensor or a large-sized magnet.SOLUTION: A position detecting device is provided with a reflection type photosensor 7 having a light-emitting device 9 and a light receiving element 10 and a reflection board 8 in which a shape having an acclivity Ka and a declivity Kb with respect to the direction of movement. In the light receiving element 10, a light receiving region which increases in area per unit length from the center portion in the moving direction to both ends is provided in order that the detection output changes linearly in accordance with the travel of the reflection board 8, and the reflection board 8 is arranged such that it moves in a direction almost parallel to the light emitting/receiving surface Sand almost perpendicular to the direction connecting the light-emitting device 9 to the light receiving element 10. Thereby, linearity is obtained in a long distance and detection at high resolution can be conducted.

Description

  The present invention relates to a position detection device using a reflective photosensor, and more particularly to a device for detecting the position of a moving object in a device such as a camera.

  Conventionally, for example, various cameras, mobile phones with zoom function cameras, etc., use various actuators to drive the lens, and a position detection device (sensor) is used to grasp the position of the movable lens or the like. It is done.

  For example, as a detection device for the position and movement amount of the focus lens, there are a type that uses a pulse generator in a stepping motor system and a type that detects a change amount in an analog manner using a magnetic sensor or an optical sensor in a piezo motor system. Examples of the former include Japanese Patent Application Laid-Open No. 04-9712 (Reference 1), and examples of the latter include Japanese Patent Application Laid-Open No. 05-45179 (Reference 2) and Japanese Patent Application Laid-Open No. 2002-357762 (Reference 3). Is mentioned.

  For example, in digital still cameras, the stepping motor method has been the mainstream until now, but in recent years the piezo motor method has been used in order to avoid the generation of audio noise during movie shooting and to reduce the size of applications. . The distance range required for position detection required for the application of this digital still camera is generally 5 mm or more although it depends on the specification.

  In addition, in the piezo motor system, in recent years, a position detection device has been incorporated for the purpose of detecting the position of an autofocus lens of a mobile phone with a camera function, and the movement distance range required for position detection required in this case is as follows. About 0.7 mm is sufficient.

  On the other hand, as a position detection device, a device using a reflective photosensor is adopted. This reflective photosensor not only detects the presence or absence of an object in a non-contact manner, but also detects an analog amount such as a position and a movement amount. It is an optical sensor that can perform the above. In this position detection apparatus using a reflection type photosensor, for example, detection of a focus lens position in an autofocus camera is performed. As an example of improving the position detection and movement amount detection performance, Japanese Patent Application Laid-Open No. 2006-2006. There are techniques such as JP-173306 (reference 4) and JP-A-2007-203698 (reference 5). In addition, an example in which the linearity of the output signal is improved by using a reflective photosensor is disclosed in Japanese Patent Application Laid-Open No. 2009-38321 (Document 6).

  FIG. 9 shows a position detection apparatus using a conventional general reflection type photosensor, and FIG. 10 shows a configuration of the reflection type photosensor. In FIG. 10, the reflective photosensor 1 has two concave portions separated by a light shielding wall 2, and has a configuration in which the light emitting element 3 is disposed in one concave portion and the light receiving element 4 is disposed in the other concave portion. .

Then, as shown in FIG. 9, the light emitting / light receiving surface S _L side of photo sensor 1 so as to move parallel to the light-emitting / light receiving surface S _L, and the linear direction connecting the light emitting element 3 and light receiving element 4 In addition, the reflector 5 is disposed. According to such a configuration, the light from the light emitting element 3 is reflected by the reflecting plate 5 and input to the light receiving element 4, and the position and moving distance of the reflecting plate 5 are detected based on the amount of received light.

  FIG. 11 shows the detection result of the moving distance in the conventional reflective photosensor [reflector moving distance−relative output (Io) of the output current of the photosensor]. In this example, 0.8 mm Linear characteristics are obtained at a distance of ˜1.5 mm, i.e. about 0.7 mm. Such a position detection device using a reflective photosensor is generally used when the movement range is about 0.7 mm, for example, for detecting the position of a piezo motor type focus lens.

Japanese Patent Laid-Open No. 04-9712 JP 05-45179 A JP 2002-357762 A JP 2006-173306 A JP 2007-203698 A JP 2009-38321 A

  However, in the case of detecting the lens position of a camera module equipped with a zoom function, such as a digital still camera, a mobile phone with a zoom function camera, a single-lens reflex camera or a camcorder, position detection in a long distance range of about 5 mm to 10 mm is necessary. It has been difficult to use an apparatus using the above-described reflective photosensor.

  On the other hand, for applications that require long-distance detection, it is common to use a stepping motor system that rotates by a specific rotation angle according to the count of the number of pulses that are generated. There is a problem that this noise is large, and this noise leads to the generation of audio noise during video shooting.

  In recent years, in order to provide a high-speed autofocus function or to reduce the size of an application, a piezo motor system is often used. However, for position detection using a piezo motor system with a distance of 5 mm or more, a configuration in which a plurality of magnetic sensors (MR elements or Hall elements) and a magnet that covers these elements is generally used is the mainstream. It was getting bigger. In addition, when other magnetism is used in an application in which such a magnetic sensor or the like is mounted, there is a problem that malfunction may occur due to the influence of magnetic fogging.

  In addition, when using a magnetic sensor, the output of each sensor must be input to an ADC (analog-digital converter) via an operational amplifier or as an integrated circuit built-in sensor output, and the component costs for configuring the system There is a problem that becomes expensive.

  Furthermore, in the configuration of FIG. 9, when a long distance of 1 mm or more is detected by only one reflective photosensor 1, the size of the light emitting element 3 must be increased, which is necessary on the light receiving element side. Since a die that secures a light receiving area that is equal to or greater than the detection distance is mounted, there is a problem in that the outer size of the photosensor 1 is increased and the cost of components is significantly increased.

  In addition, the position detection device using the reflective photosensor 1 is required to be capable of detecting a long distance and having high resolution.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is to achieve a good position sensing of 1 mm or more with a simple and small configuration without using a magnetic sensor or a large magnet, and with a high resolution. An object of the present invention is to provide a position detection device using a reflective photosensor that can be detected.

In order to achieve the above object, a position detection apparatus using a reflective photosensor according to the invention of claim 1 includes a reflective photosensor having a light emitting element and a light receiving element, and a light emitting / receiving surface of the photosensor. A reflection part or a reflection pattern arranged so as to move a predetermined distance in parallel, and having a shape having an ascending slope and a descending slope with respect to the moving direction, and based on light emission of the light emitting element The moving position of the reflection unit is detected from the output of the photosensor that receives light reflected from the reflection unit by the light receiving element.
According to a second aspect of the present invention, there is provided a reflective photosensor having a light emitting element and a light receiving element, and a direction substantially parallel to a light emitting / receiving surface of the photosensor and substantially perpendicular to a direction connecting the light emitting element and the light receiving element. A reflection portion or a reflection pattern arranged to move a predetermined distance and formed with a shape having an inclination with respect to the moving direction, and is detected by the light emitting element of the reflection type photosensor. A light emitting region having a larger area per unit length from the center to the both ends of the reflecting portion moving direction is provided so that the output changes linearly according to the moving amount of the reflecting portion, or the light receiving element In addition, a light receiving region is provided in which the area per unit length increases toward the both ends from the center of the reflecting portion moving direction so that the detection output changes linearly according to the amount of movement of the reflecting portion. Light-emitting element The light reflected from the reflecting portion based on the light and detecting the moving position of the reflective portion of the output of the photo sensor receiving at the light receiving element.
The invention according to claim 3 is characterized in that the reflecting portion is formed with a shape having an upward inclination and a downward inclination with respect to the moving direction.
The invention of claim 4 is characterized in that the reflecting portion is formed with a shape in which an upward inclination and a downward inclination are repeated with respect to the moving direction.

  According to the first aspect of the present invention, for example, a reflective part (a reflective plate or a reflective pattern composed of a high reflective part and a light-shielding part) is attached to a movable lens of a camera and the movement position of the reflective part is set to the reflective photosensor. By detecting the position, the position (or distance) of the movable lens or the like can be specified. In this detection, the output of the reflective photosensor can maintain linearity (linearity) at a distance of 1 mm or more, and the resolution can be increased by the shapes of the upward and downward inclinations of the reflecting portion or the repeated shapes thereof. It is possible to detect the moved position.

According to the configuration of the second aspect, as the reflection type photosensor, the unit length increases from the central part in the reflection part moving direction toward both ends so that the detection output changes linearly according to the movement amount of the reflection part. Using a light-receiving area or light-emitting area with a wide area, and the reflecting part being substantially parallel to the light emitting / receiving surface of the photosensor and substantially perpendicular to the direction connecting the light emitting element and the light receiving element By arranging so as to move to, it is possible to obtain a detection output in which linearity is maintained at a distance of 1 mm or more. In this case, linearity can be maintained over a long distance by reducing the inclination angle of the reflecting portion (for example, ascending inclination).
According to the configuration of the third or fourth aspect, detection with high resolution is performed.

  According to the position detection device of the present invention, position sensing can be performed with good linear characteristics over a long distance range of 1 mm or more or 5 mm or more with a simple and small configuration without using a magnetic sensor or a large magnet. Further, the position detection with a small size and high resolution (high accuracy) can be realized at low cost by the shapes of the upward and downward inclinations or the repeated shapes thereof. Accordingly, in the lens position detection of a camera module that requires a zoom function, such as a digital still camera, a mobile phone with a zoom function camera, a single-lens reflex camera, and a camcorder, it is possible to detect a position over a long distance of about 1 mm to 10 mm. is there.

The structure of the position detection apparatus which concerns on 1st Example of this invention is shown, A figure (A) is a top view, A figure (B) is a side view. The structure of each member of the position detection apparatus according to the first embodiment is shown, in which FIG. (A) is a configuration diagram of another example of the reflecting plate, and FIG. (B) is a configuration diagram of the reflective photosensor. It is a graph which shows the example of a characteristic (movement distance-relative output) using the repeated inclination shape in the position detection apparatus of 1st Example. It is a figure which shows the structure of the position detection apparatus of 2nd Example. It is a graph which shows the example of a characteristic at the time of using the reflecting plate of inclination-angle 3 degrees in 2nd Example (movement distance-relative output). It is a figure which shows the structure of the position detection apparatus of 3rd Example. It is a graph which shows the example of a characteristic (movement distance-relative output) when changing the inclination-angle of the upward inclination part in the position detection apparatus of 3rd Example. It is a graph which shows the example of a characteristic (movement distance-relative output) when changing the inclination-angle of the upward inclination part in the position detection apparatus of 1st Example. The structure of the conventional position detection apparatus is shown, A figure (A) is a top view, A figure (B) is a side view. It is a figure which shows the structure of the reflection type photosensor of the conventional position detection apparatus. It is a graph which shows the example of a characteristic [movement distance-relative output (Io)] of the conventional position detection apparatus.

FIGS. 1 and 2 show the configuration of a position detection device using a reflective photosensor according to a first embodiment of the present invention. the light receiving surface S _L side, parallel to the light-emitting / light receiving surface S _L, and to move in a direction substantially perpendicular to the line direction connecting the light emitting element 9 and the light receiving element 10, the reflection plate 8 is arranged. The reflecting plate 8 is connected to a movable body such as a lens and is configured to move integrally with the movable body.

  As shown in FIG. 2B, the photosensor 7 of the first embodiment has a light emitting element 9 in the lower concave portion and two light receiving elements 10 in the upper concave portion separated by the light shielding wall 11. The photosensor 7 is configured to cover the active layer of the light receiving element 10 with a light-shielding reflective film (AL film) 10a, as in the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 2009-38321). Thus, a light receiving region 10b is provided in which the area per unit length increases toward the both ends from the central portion in the moving direction of the reflecting plate 8. Thereby, the moving distance of the reflecting plate 8 from which the detection output which changes to linearity is obtained can be lengthened. On the other hand, the light emitting region of the light emitting element 9 is also formed so that the length in the moving direction is longer than that of the conventional one. The photosensor 7 has a configuration similar to that of the light receiving element 10 by covering a part of the light emitting element 9 with a light-shielding film or the like, and the light receiving element 10 is configured similarly to the light emitting element 9. Thus, the light emitting element 9 may be formed with a light emitting region in which the area per unit length becomes wider from the central portion in the moving direction of the reflector 8 toward both ends, and this also changes to linearity. The moving distance of the reflecting plate 8 from which the detection output can be obtained can be increased.

  As shown in FIG. 1A, the upper part of the reflector 8 of the first embodiment has a shape having, for example, a downward inclination Kb having the same angle as an upward inclination Ka having an angle θ = 20 degrees. Further, as shown in FIG. 2A, a shape (pattern) in which three or more ascending slopes Ka and descending slopes Kb having an angle θ = 20 degrees are repeated may be formed as the reflector 18 having another configuration. it can. As described above, in the first embodiment, by providing the ascending slope Ka and the descending slope Kb, and by repeatedly providing the ascending slope Ka and the descending slope Kb, the movement position of the reflector 8 that moves over a long distance is linear. It becomes possible to detect the characteristic with high resolution.

  FIG. 3 shows the detection characteristics of the position detection device when the reflector 18 (repetitive shape) of FIG. 2 (A) is used. In the first embodiment, a in FIG. Is a change amount due to the downward slope Kb, and a and b are repeated in a range of about 1 to 12 mm. Accordingly, the peak point of each output of c to f and the bottom point of each output of g to i, or any one of them are counted and integrated, thereby reflecting the reflector 8 over a long distance range. Thus, the total movement distance can be detected. According to this, not only the moving position of the reflecting plate 8 at a long distance can be detected, but also the detection can be performed with high resolution (high accuracy) by adopting a shape that repeats the upward inclination Ka and the downward inclination Kb.

  That is, when it is necessary to perform detection with a high resolution, the angle θ between the upward slope Ka and the downward slope Kb is increased, and a repeated pattern having a shape in which the amount of change in a and b in FIG. The gradient (change amount) of the output signal of the photosensor 8 may be increased.

FIG. 4 shows the configuration of the second embodiment. This second embodiment has the same photosensor 7 as that of the first embodiment and a reflector 14 having one inclined portion. As shown in FIG. 4, the photosensor 7 is provided with a light emitting element 9 and a light receiving element 10, and the light emitting / receiving surface 10 on the light emitting / receiving surface _SL side (the back side in the figure) of the photosensor 7. parallel to the plane S _L, and to move in a direction substantially perpendicular to the line direction connecting the light emitting element 9 and the light receiving element 10, the reflecting plate 14 is disposed. In the reflecting plate 14, an upward inclination (or downward inclination) Kc is formed with the angle θ being a small angle, for example, 3 degrees. And it comprises so that it may detect from the start position shown in FIG.

  FIG. 5 shows an example of characteristics (measurement example) of the second embodiment. In the second embodiment, a highly accurate linearity of about 10 mm is obtained by setting the inclination angle of the reflector 14 to 3 degrees. Characteristics are obtained. The absolute value of the linearity characteristic of the reflective photosensor 7 obtained by detecting the position of the reflecting plate 14 depends on the angle θ of the reflecting plate 14, and the smaller the angle θ is set, the higher the linearity characteristic becomes. Characteristics are obtained. Therefore, desired linearity characteristics can be obtained by arbitrarily setting the angle θ corresponding to the required linearity width.

FIG. 6 shows the configuration of the third embodiment. This third embodiment uses the photosensor 1 shown in FIG. 10 described in the prior art and the reflector 16 having the upward slope Ka and the downward slope Kb. It was. In this case, as shown in FIG. 6, the reflecting plate 16 is substantially parallel to the light emitting / receiving surface (S _L ) of the photosensor 1 and substantially perpendicular to the direction connecting the light emitting element 3 and the light receiving element 4. It is arranged to move a predetermined distance.

  FIG. 7 shows the characteristics of the upward slope Ka portion when the angle θ of the reflector 16 is swung from 90 degrees (graph line 101) to 7 degrees (graph line 105) in the configuration of the third embodiment. Has been. As can be seen from FIG. 7, in the third embodiment, when the inclination angle θ is 10 degrees (graph line 104) or 7 degrees (graph line 105), a linearity characteristic of about 2 mm or more can be obtained.

  In FIG. 8, the photosensor 1 of the third embodiment is replaced with the photosensor 7 used in the first embodiment (a configuration substantially similar to that of FIG. 1A), and the angle θ is similarly set to 90 degrees (graph line). 201) to 7 degrees (graph line 205), and the characteristics are shown. In this example, if the inclination angle θ is 10 degrees (graph line 204) or 7 degrees (graph line 205), A linearity characteristic of about 4 mm or more is obtained.

  Further, in FIGS. 7 and 8, for example, when the length of the moving distance of the reflector 16 in a region where the relative output linearly changes from 0.1 to 0.9 when the inclination angle θ is 7 degrees is compared, The result of FIG. 7 (when using the photosensor 1 [FIG. 10]) is 2.8 mm, whereas the result of FIG. 8 (when using the photosensor 7 [FIG. 2B]) is 5 If the photo sensor 7 that is optimally designed to improve the linearity characteristic is used, the linearity characteristic can be realized at a longer distance.

  In the above-described embodiment, an example in which a reflection plate is used as the reflection portion has been described. However, it is also possible to use a plate-like or columnar member formed with a reflection pattern composed of a high reflection portion and a light shielding portion.

  The present invention can be used as a position detection device incorporating a piezo motor, for example, a digital still camera, a cellular phone with a zoom function camera, a single lens reflex camera, a camcorder, or a lens position detection device for a camera module that requires a zoom function. In such position sensing of 1 mm or more, it is possible to reduce the size and to realize an inexpensive system configuration.

1, 7 ... reflective photosensors, 3, 9 ... light emitting elements,
4, 10 ... light receiving element, 5, 8, 14, 16, 18 ... reflector,
Ka, Kc ... ascending slope, Kb ... descending slope,
S _L ... Light emitting / receiving surface.

Claims (4)

A reflective photosensor having a light emitting element and a light receiving element;
A reflecting portion or a reflecting pattern arranged so as to move a predetermined distance substantially parallel to the light emitting / receiving surface of the photosensor, and having a shape having an upward slope and a downward slope with respect to the moving direction; Provided,
Position detection using a reflective photosensor, wherein a moving position of the reflective portion is detected from an output of the photosensor that receives light reflected from the reflective portion on the basis of light emitted from the light emitting element. apparatus. A reflective photosensor having a light emitting element and a light receiving element;
It consists of a reflector or a reflection pattern arranged so as to move a predetermined distance in a direction substantially parallel to the light emitting / receiving surface of the photosensor and substantially perpendicular to the direction connecting the light emitting element and the light receiving element. And a reflection part formed with a shape having an inclination with respect to,
The area per unit length from the center of the reflection unit moving direction to both ends so that the detection output of the light emitting element of the reflection type photosensor linearly changes according to the amount of movement of the reflection unit. A light emitting area is provided, or the unit length increases toward the both ends from the center of the moving direction of the reflecting part so that the detection output of the light receiving element changes linearly according to the moving amount of the reflecting part. Provide a light receiving area that increases the contact area,
Position detection using a reflective photosensor, wherein a moving position of the reflective portion is detected from an output of the photosensor that receives light reflected from the reflective portion on the basis of light emitted from the light emitting element. apparatus.   The position detecting device using a reflective photosensor according to claim 2, wherein the reflecting portion is formed with a shape having an upward inclination and a downward inclination with respect to the moving direction.   4. The position detecting device using a reflective photosensor according to claim 1, wherein the reflecting portion is formed with a shape in which an upward inclination and a downward inclination are repeated with respect to the moving direction.

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