JP2005106604A - Optical encoder and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten detection accuracy of an optical encoder for introducing light from a light source into an optical sensor through the first scale and the second scale, and detecting the position of one movable scale based on the light receiving quantity of the optical sensor fluctuating following the movement. <P>SOLUTION: A lens 25 for imaging light from the first scale 23 on the second scale 24 is provided between the first movable scale 23 and the second fixed scale 24, to thereby clarify the boundary between a bright part and a dark part formed on the second scale 24. The lens 25 can be integrated with the second scale 24, and the first scale 23 can be fixed and the second scale 24 can be movable. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical encoder that detects the position of a movable member using light, and an optical device including the optical encoder.

  Between the light source and the optical sensor, two scales in which a transmission part that transmits light and a reflection part that reflects light are alternately arranged are arranged to face each other, and one scale is arranged in the arrangement direction of the transmission part and the reflection part. An optical encoder that detects the position of the movable scale by utilizing the fact that the amount of light received by the optical sensor varies as the movable scale moves is used in various devices. The movable scale is attached to a movable member whose position is to be detected.

  The reflection part provided in the scale has been comprised with the metal film | membrane with a high reflectance. When the reflective portion is formed of a metal film, it is possible to use a photolithography technique, whereby the arrangement pitch between the transmissive portion and the reflective portion can be reduced, and a highly accurate optical encoder can be obtained. . However, scale productivity is not so high.

  In recent years, a reflection part has also been proposed in which a scale is made of a transparent resin, a groove or a ridge having an inclined surface is provided on the surface thereof, and total reflection on the inclined surface is used (see, for example, JP-A-3-197819). ). Such a scale can be manufactured by molding and has high mass productivity.

  An example of an optical encoder provided with a scale having grooves formed on the surface is shown in FIG. This optical encoder includes a light source 51 that emits light, an optical sensor 52 that detects light, a movable scale 53, and a fixed scale 54. A groove having a slope is provided on the lower surface of the movable scale 53 and the fixed scale 54. It has been. The arrangement direction of the grooves of the movable scale 53 and the arrangement direction of the grooves of the fixed scale 54 are parallel, and the movable scale 53 moves in the groove arrangement direction (indicated by an arrow M).

  The light emitted from the light source 51 enters the inside of the fixed scale 54, a part of which enters the flat part of the lower surface and passes through, and the rest enters the inclined surface of the groove and is totally reflected. It is incident on the slope and totally reflected. That is, the flat part of the lower surface is the transmission part, and the groove is the reflection part.

  The light from the transmission part on the lower surface of the fixed scale 54 enters the movable scale 53 and enters the lower surface thereof. On the lower surface of the movable scale 53, a bright portion and a dark portion corresponding to the transmission portion and the reflection portion on the lower surface of the fixed scale 54 are generated. A part of the light forming the bright part on the lower surface of the movable scale 53 is transmitted through the flat transmission part and enters the optical sensor 52, and the rest is totally reflected by the reflection part of the slope. The amount of light incident on the optical sensor 52 depends on the relative position of the movable scale 53 with respect to the fixed scale 54, and varies periodically according to the movement of the movable scale 53. Therefore, the position of the movable scale 53 can be detected based on the variation in the amount of light received by the optical sensor 52.

  In the optical encoder shown in FIG. 28, an optical sensor that condenses the light near the parallel light from the lens 55 that guides the diverging light emitted from the light source 51 close to the parallel light to the fixed scale 54 and the movable lens 53. A lens 56 leading to 52 is provided.

It is also possible to replace the movable scale 53 and the fixed scale 54 so that the light from the movable scale 53 is guided to the fixed scale 54. Japanese Patent Laid-Open No. 3-197819 also discloses an arrangement in which the surface of the movable scale 53 provided with the grooves and the surface of the fixed scale 54 provided with the grooves are opposed to each other.
Japanese Unexamined Patent Publication No. 3-197819

  In the conventional optical encoder, since the light from one scale is directly incident on the other scale, the boundary between the bright part and the dark part on the latter tends to be unclear. For this reason, fluctuations in the amount of light received by the optical sensor are also obscured, and it is difficult to detect the position unless the arrangement pitch of the transmitting and reflecting parts of the fixed scale and the movable scale is larger than a certain degree. Therefore, the advantage that the arrangement pitch of the transmission part and the reflection part of the scale having the reflection part of the metal film can be made extremely small cannot be fully utilized.

  As described above, the resin scale having grooves and wrinkles on the surface can be produced by molding, and has a feature of high mass productivity. However, when the width of the groove or ridge is reduced, in the molding, the edge portion where the plane intersects the plane becomes a curved surface, and the shape as designed cannot appear. If the shape of the groove or ridge is not as designed, total reflection becomes insufficient, the width of the received light amount of the optical sensor that varies due to the movement of the movable scale becomes narrow, and it becomes difficult to detect the variation in the received light amount. For this reason, there is a lower limit to the pitch of the scale grooves and ridges produced by molding.

  It is also possible to use one having a reflective part of a metal film as one of the fixed scale and the movable scale and the other having a groove or a ridge produced by molding. However, in the optical encoder having such a configuration, the detection accuracy is defined by the arrangement pitch of the scale grooves and ridges manufactured by molding, and the relatively high accuracy of the scale having the reflective portion of the metal film cannot be utilized.

  The present invention has been made in view of such problems, and provides an optical encoder with high detection accuracy in which the boundary between a bright part and a dark part formed on one scale by one scale is clear. With the goal. It is another object of the present invention to provide an optical device that includes such an optical encoder and can accurately detect the position of a movable member.

  In order to achieve the above object, in the present invention, a light source that emits light, a first scale having a plurality of light guides arranged in a spaced manner to allow light from the light source to travel in a predetermined direction, A second scale having a plurality of light guides arranged to be spaced apart to advance light from the light guide part in a predetermined direction, and detecting the amount of light received by receiving light from the light guide part of the second scale And one of the first scale and the second scale is movable in the arrangement direction of the light guides, and the position of the scale is determined based on the change in the amount of light received by the optical sensor due to the movement of the scale. A configuration in which an optical optical system for detection includes an imaging optical system that forms an image of light from the light guide of the first scale on the second scale between the first scale and the second scale. To do.

  The optical encoder includes an imaging optical system between the first scale and the second scale, thereby imaging light from the light guide portion of the first scale on the second scale. . Therefore, an image composed of a bright portion corresponding to the light guide portion of the first scale and a dark portion corresponding to the space between the light guide portion and the light guide portion of the first scale is clearly formed on the second scale. As a result, the boundary between the bright part and the dark part on the second scale is clear. For this reason, even if the arrangement pitch of the light guides of the first scale and the second scale is small, the amount of received light detected by the optical sensor corresponds to the movement of the movable scale (first scale or second scale). It is possible to ensure the detection accuracy defined by the arrangement pitch of the light guides of the first scale and the second scale.

  Note that the light guides of the first scale and the second scale may transmit light or reflect light. The part between the light guide part and the light guide part of the first scale and the second scale may also reflect light or transmit light.

  The imaging magnification by the imaging optical system may be arbitrarily determined. When the imaging magnification is 1, the arrangement pitch of the light guide portions of the first scale and the second scale is made equal. When the imaging magnification is less than 1, the arrangement pitch of the light guides of the second scale is made smaller than the arrangement pitch of the light guides of the first scale. This setting is suitable when a first scale having a groove or a ridge is used and a second scale having a metal film between the light guide and the light guide. When the imaging magnification exceeds 1, the arrangement pitch of the light guides of the second scale is made larger than the arrangement pitch of the light guides of the first scale. This setting is suitable when the first scale having a metal film between the light guide and the light guide is used, and the second scale having a groove or a ridge on the surface.

  Here, the non-movable scale of the first scale and the second scale, the light source, and the optical sensor may be configured to be fixed to the same member. In this way, it becomes easy to ensure accuracy, and it is easy to incorporate into an apparatus equipped with an optical encoder.

  A deflecting optical system for bending the light path of the light from the light source and directing the light from the light source toward the first scale may be provided between the light source and the first scale. If it does in this way, it will become unnecessary to arrange a light source toward the 1st scale, and restrictions on composition will decrease.

  The imaging optical system may be configured to be either a Fresnel lens or a diffractive lens. The Fresnel lens is an element that produces a condensing action by refraction but is thin, and the diffractive lens is a lens that produces a condensing action by diffraction and is also thin, both of which are the first scale and the second scale. An increase in the interval can be suppressed.

  The optical power of the imaging optical system can be set differently in the direction parallel to the direction in which the light guides of the second scale are arranged and in the direction perpendicular thereto. The bright part and the dark part of the image on the second scale need only have a clear boundary perpendicular to the arrangement direction of the light guides, and the boundary parallel to the arrangement direction may not be clear. By making the power of the imaging optical system match this condition, the imaging optical system itself can be easily manufactured while ensuring high detection accuracy.

  The non-movable scale of the first scale and the second scale and the imaging optical system may be provided on the opposing surfaces of the same transparent member. If it does in this way, it becomes possible to manufacture a non-movable scale and an imaging optical system at a time by molding, and manufacturing efficiency improves. In addition, it is easy to reduce the interval between the first scale and the second scale.

  In order to achieve the above object, according to the present invention, in the optical device including the movable optical member, any one of the above-described optical encoders is movable between the first scale and the second scale. The position of the movable optical member is detected by an optical encoder.

  In the optical encoder of the present invention, on the second scale, the boundary between the bright part corresponding to the light guide part of the first scale and the dark part corresponding to the space between the light guide part and the light guide part is clarified. The detection accuracy defined by the arrangement pitch of the light guides of the first scale and the second scale can be ensured. Further, the arrangement pitch of the light guide portions of the first scale and the second scale can be different depending on the imaging magnification of the imaging optical system, and the manufacturing method can be used as the first scale and the second scale. It is possible to adopt a different one. At least one of the first scale and the second scale can be made of a resin having grooves or wrinkles on the surface, which can be manufactured by molding, and mass productivity is increased.

  The optical device of the present invention can detect the position of the movable member with high accuracy and can be easily reduced in size and cost due to the above-described effects of the optical encoder. For example, an imaging device that detects the position of a movable lens included in an imaging optical system with an optical encoder is suitable as an imaging means for a portable telephone having an imaging function.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the optical encoder 1 of the first embodiment is shown in FIGS. FIG. 1 is a cross-sectional view in which different vertical cross sections are combined, and FIG. 2 is a perspective view. The optical encoder 1 includes a light source 21 that emits light, an optical sensor 22 that receives light and detects the amount of received light, a first scale 23, a second scale 24, and a lens 25. The light source 21 is, for example, a light emitting diode (LED), and the optical sensor 22 is, for example, a photodiode (PD). The light source 21 and the optical sensor 22 are provided on the same substrate 20.

  The second scale 24 is located between the first scale 23 and the optical sensor 22. A plurality of grooves 23c having two inclined surfaces are formed on the surface 23a of the first scale 23 on the side far from the light source 21, and the surface 24a on the side of the second scale 24 near the photosensor 22 also has 2 A plurality of grooves 24c each having one inclined surface are formed.

  The surface 23b where the groove 23c of the first scale 23 is not formed is a flat surface, and a portion between the groove 23c and the groove 23c of the surface 23a is parallel to the surface 23b. Similarly, the surface 24b where the groove 24c of the second scale 24 is not formed is a flat surface, and the portion between the groove 24c and the groove 24c of the surface 24a is parallel to the surface 24b.

  The plurality of grooves 23c of the first scale 23 are parallel to each other, and their size (width and depth) and arrangement pitch are constant. Further, the width of the portion between the groove 23c and the groove 23c is equal to the width of the groove 23c. The plurality of grooves 24c of the second scale 24 are also parallel to each other, and their size and arrangement pitch are also constant. Moreover, the width | variety of the site | part between the groove | channel 24c and the groove | channel 24c is equal to the width | variety of the groove | channel 24c. Furthermore, the arrangement direction of the grooves 23c and the arrangement direction of the grooves 24c are parallel.

  As a material for the first scale 23 and the second scale 24, in addition to glass, resins such as polycarbonate, acrylic, polystyrene, and zeonore that are generally used as optical materials can be used. The grooves 23c and 24c can be formed by cutting with a cutting tool. When a resin material is used, the grooves 23c and 24c are formed at the same time as the production of the scales 23 and 24 by molding using a die having a complementary shape. It is also possible.

  In FIG. 1, in order to explain the principle of position detection in the optical encoder 1, the direction connecting the light source 21 and the optical sensor 22 is the arrangement direction of the grooves 23 c of the first scale 23 or the second scale 24. 2, the direction in which the light source 21 and the optical sensor 22 are connected is actually the direction in which the grooves 23 c of the first scale 23 are arranged, as shown in FIG. 2. Or, it is perpendicular to the arrangement direction of the grooves 24 c of the second scale 24.

  The optical encoder 1 is used in a form in which a first scale 23 is attached to a movable member (not shown) whose position is to be detected. The first scale 23 includes a light source 21, an optical sensor 22, and a second scale. 24 and the lens 25 are relatively movable. The first scale 23 is attached so that the arrangement direction of the grooves 23c matches the moving direction of the movable member (indicated by the arrow M).

  The lens 25 is located between the first scale 23 and the second scale 24. The second scale 24 and the lens 25 are fixed to the substrate 20 provided with the light source 21 and the optical sensor 22, and the light source 21, the optical sensor 22, the second scale 24, and the lens 25 are a single unit. It has become. This unit is arranged so that the surface 24a where the groove 24c of the second scale 24 is formed is parallel to the surface 23a where the groove 23c of the first scale 23 is formed.

  Light emitted from the light source 21 passes through the surface 23b from an oblique direction, enters the first scale 23, and reaches the surface 23a where the groove 23c is formed. Part of this light is incident on and transmitted through a flat portion between the grooves 23c, and the rest is incident on the inclined surface of the groove 23c and is totally reflected. The light totally reflected by the slope of the groove 23c enters the adjacent slope, is totally reflected again, and passes through the surface 23b.

  The light totally reflected by the inclined surface of the groove 23c and transmitted through the surface 23b is incident on the lens 25 and is transmitted therethrough. The light transmitted through the lens 25 passes through the surface 24b, enters the second scale 24, and reaches the surface 24a where the groove 24c is formed. On the surface 24a, a bright part corresponding to the groove 23c of the surface 23a of the first scale 23 and a dark part corresponding to a portion between the groove 23c and the groove 23c are formed.

  A part of the light reaching the surface 24a is incident on and transmitted through a flat portion between the grooves 24c and 24c, and the rest is incident on the inclined surface of the groove 24c and totally reflected. The light totally reflected by the slope of the groove 24c enters the adjacent slope, is totally reflected again, and passes through the surface 24b. The light transmitted through the portion between the groove 24c and the groove 24c on the surface 24a is incident on the optical sensor 22, and the amount of light is detected by the optical sensor 22.

  The positions of the bright part and the dark part on the surface 24 a of the second scale 24 are determined by the position of the first scale 23 with respect to the second scale 24 and change according to the movement of the first scale 23. Therefore, the amount of light that passes through the portion between the groove 24c and the groove 24c on the surface 24a and reaches the optical sensor 22 also varies according to the movement of the first scale 23. The position of the scale 23 and the movable member to which the scale 23 is attached can be detected. FIG. 3 shows how the intensity of the output signal of the optical sensor 22 representing the amount of received light varies as the first scale 23 moves.

  In the first scale 23, the groove 23c that totally reflects the light serves as a light guide unit that causes the light to travel in the direction of the second scale 24. In the second scale 24, the portion between the groove 24c and the groove 24c. However, the light guide unit advances the light in the direction of the optical sensor 22. In both the first scale 23 and the second scale 24, the inclined surfaces of the grooves 23c and the grooves 24c need to reliably totally reflect light. Taking the groove 23c as an example, the setting of the slope will be described with reference to FIG.

  When a general glass or resin is used as the material of the first scale 23, its refractive index is about 1.5, so the critical angle is about 42 °. Therefore, when light is incident on the surface 23a perpendicularly (incidence angle 0 °), if the angle α formed by the two inclined surfaces of the groove 23c shown in FIG. The angle exceeds the critical angle and total reflection occurs. Actually, since the light enters the groove 23c from an oblique direction (a direction away from the paper surface of FIG. 4), the incident angle of the light with respect to the inclined surface is further increased. The light from the light source 21 is divergent light, and the incident angle with respect to the inclined surface is slightly different depending on the light beam. However, if the angle α formed by the two inclined surfaces is set to about 90 °, total reflection can be surely generated by the inclined surface. .

  These also apply to the groove 24c of the second scale 24. The light incident on the surface 23a of the first scale 23 and the surface 24a of the second scale 24 is generally along a plane parallel to the grooves 23c and 24c (a plane perpendicular to the arrangement direction of the grooves 23c and 24). Therefore, the individual grooves 23c and 24c have two slopes having the same size and are symmetrical with respect to the arrangement direction of the grooves 23c and 24c.

  The lens 25 functions as an imaging optical system, and images light from the surface 23 a (groove 23 c) of the first scale 23 on the surface 24 a of the second scale 24. Therefore, the boundary between the bright part and the dark part formed on the surface 24a of the second scale 24 is clear. FIG. 5 shows images of bright portions and dark portions formed on the surface 24a. In FIG. 5, the shaded portion is a dark portion, and the blank portion is a bright portion.

  When the processing accuracy of the movable member to which the first scale 23 is attached is not so high, or an error occurs in the position setting of the unit composed of the light source 21, the optical sensor 22, the second scale 24, and the lens 25 with respect to the movable member. The interval between the first scale 23 and the second scale 24 does not become as designed. However, even if the distance between the first scale 23 and the second scale 24 slightly deviates from the design value, the surface 23a of the first scale 23 is highly likely to be within the depth of field of the lens 25, and the design value Unless the deviation from is excessive, the boundary between the bright part and the dark part is clear.

  The imaging magnification of the lens 25 can be arbitrarily determined. The ratio of the arrangement pitch of the grooves 24 c of the second scale 24 to the arrangement pitch of the grooves 23 c of the first scale 23 is made equal to the imaging magnification of the lens 25. In other words, the imaging magnification of the lens 25 is set according to the ratio of the arrangement pitch of the grooves 24c of the second scale 24 to the arrangement pitch of the grooves 23c of the first scale 23. As a result, the incident timing of light to each light guide portion (the portion between the groove 24a and the groove 24a) of the second scale 24 is aligned with the movement of the first scale 23, and the amount of light received by the optical sensor 22 varies. The width is maximum.

  Hereinafter, other embodiments will be described. Components having the same or similar functions as those of the optical encoder 1 according to the first embodiment are denoted by the same reference numerals, and redundant description will be omitted. Further, when only some of the components are different, the illustration of other components is omitted as appropriate.

  The first scale 23 of the optical encoder 2 of the second embodiment is shown in FIG. In the present embodiment, a plurality of ridges 23d are formed on the surface 23a of the first scale 23 far from the light source 21 instead of the grooves 23c. The plurality of ridges 23d are equal in size and are parallel to each other. Further, the width of the portion between the flanges 23d and 23d is equal to the width of the flanges 23d, and the arrangement pitch of the flanges 23d is constant. A part of the light from the light source 21 is incident on and transmitted through the portion between the ridges 23d and 23d, and the rest is incident on the inclined surface of the ridge 23d and totally reflected, and further incident on the adjacent inclined surface. Reflected. In the present embodiment, the eaves 23 d serve as the light guide portion of the first scale 23 that advances the light from the light source 21 in the direction of the second scale 24.

  The distance between the adjacent slopes of the flange 23d that totally reflects the light in order is shorter than the distance between the slopes that totally reflects the light in the groove 23c. The incident angle to the inclined surface that first totally reflects the light differs depending on the light beam included in the light from the light source 21, and the traveling direction after the total reflection varies somewhat for each light beam. For this reason, when the distance between the two slopes that totally reflects light in order is long, a situation may occur in which the light that has been totally reflected once passes by the neighboring slope and is not totally reflected by the neighboring slope. However, in this embodiment, since the distance between the slopes is short, almost all of the light that has been totally reflected once enters the adjacent slope and is totally reflected. Therefore, more light can be guided to the second scale 24.

  Note that, on the surface 24a of the second scale 24 on the side close to the optical sensor 22, instead of the grooves 24c, ridges of the same size, parallel to each other and arranged at a constant pitch may be formed. Good. In that case, a portion between the ridges on the surface 24 a of the second scale 24 serves as a light guide that advances the light from the first scale 23 toward the optical sensor 22.

  The configuration of the optical encoder 3 of the third embodiment is shown in FIG. In the optical encoder 3 of the present embodiment, the second scale 24 includes a first portion 24A and a second portion 24B arranged in a direction perpendicular to the arrangement direction of the grooves 24c. An optical sensor 22A that receives light and an optical sensor 22B that receives light from the second portion 24B are provided.

  FIG. 8 shows the surface 24a on which the groove 24c of the second scale 24 is formed. The size and arrangement pitch of the grooves 24c are the same in the first portion 24A and the second portion 24B, but the positions of the grooves 24c are the same in the arrangement pitch of the first portion 24A and the second portion 24B. It is set to be shifted by 1/4. This is for detecting the moving direction of the first scale 23 (which of the two movable directions is moving).

  FIG. 9 shows how the intensity of the output signals of the optical sensors 22A and 22B varies as the first scale 23 moves. When the arrangement pitch of the grooves 24c is Λ, there is a phase difference of Λ / 4 between the output signal of the optical sensor 22A and the output signal of the optical sensor 22B. The Lissajous waveform obtained by removing the bias component from the output signals of the optical sensors 22A and 22B and expressing one of the A phase and the other of the B phase in the orthogonal coordinate system will draw a circle as shown in FIG. The direction of movement of the first scale 23 is known depending on whether it is counterclockwise or counterclockwise.

  Further, one round of the Lissajous waveform corresponds to one pitch of the arrangement of the grooves 24c, and since the distance obtained by dividing the distance of one pitch from the values of the A phase and the B phase is known, the accuracy is several times the arrangement pitch of the grooves 24c. The position of the first scale 23 can be detected.

  A lens 25 of the optical encoder 4 of the fourth embodiment is shown in FIG. In FIG. 11, (a) is a sectional view and (b) is a front view. In the present embodiment, a Fresnel lens is used as the lens 25.

  A lens 25 of the optical encoder 5 of the fifth embodiment is shown in FIG. In FIG. 12, (a) is a sectional view and (b) is a front view. In the present embodiment, as the lens 25, a diffractive lens that produces a condensing action by diffraction is used. The diffractive lens is obtained by forming fine irregularities on the surface of a transparent flat plate so as to be concentric and the arrangement pitch gradually changes.

  The Fresnel lens and the diffractive lens can be made much thinner than a general lens. In the optical encoders 4 and 5 having these as the lens 25, the first scale 23 and the second scale 24 are provided. The interval can be reduced. The Fresnel lens and the diffractive lens can be manufactured by resin molding.

  The configuration of the optical encoder 6 of the sixth embodiment is shown in FIG. In the optical encoder 6 of the present embodiment, the lens 25 is a diffraction lens and is provided on the surface 24b of the second scale 24 so that the second scale 24 and the lens 25 are integrated. In this configuration, the second scale 24 and the lens 25 can be manufactured at a time by molding, and the manufacturing efficiency is improved. Further, there is no possibility of an assembly error in the relative position between the second scale 24 and the lens 25, and the imaging performance of the lens 25 is ensured.

  FIG. 13 shows a combination of different longitudinal sections similar to FIG. 1 showing the optical encoder 1 of the first embodiment, and the direction connecting the light source 21 and the optical sensor 22 is the first direction. It is perpendicular to the arrangement direction of the grooves 23 c of the scale 23 and the arrangement direction of the grooves 24 c of the second scale 24, that is, perpendicular to the paper surface. The same applies to FIGS. 14 to 19 shown below.

  The configuration of the optical encoder 7 of the seventh embodiment is shown in FIG. The optical encoder 7 is obtained by modifying the second scale 24 of the optical encoder 6 and providing a belt-shaped light-shielding film 24e on the surface 24a instead of the groove 24c. The light shielding films 24e have a constant width, are provided in parallel to each other, and are arranged at a constant arrangement pitch. The width of the portion between the light shielding film 24e and the light shielding film 24e is equal to the width of the light shielding film 24e. A portion between the light shielding film 24 e and the light shielding film 24 e serves as a light guide unit that causes light from the first scale 23 to travel in the direction of the optical sensor 22.

  As a material for the light shielding film 24e, a metal having a high reflectance or an ink having a high absorption can be used. Printing can be used when the light shielding film 24e is formed with ink, and photolithography can be used when the light shielding film 24e is formed with metal. When the light shielding film 24e is formed by photolithography using metal, the arrangement pitch of the light shielding films 24e can be made much smaller than the arrangement pitch of the grooves 24c. Any metal material may be used as long as it has a high reflectance, but aluminum, nickel, chromium, and the like that can be easily processed by photolithography are particularly preferable.

  In the optical encoder 7, the arrangement pitch of the light shielding films 24e of the second scale 24 can be made smaller than the arrangement pitch of the grooves 23c of the first scale 23, and the imaging magnification of the lens 25 can be made equal to the ratio. . This makes it possible to reduce the size of the second scale 24 while realizing high detection accuracy.

  The configuration of the optical encoder 8 of the eighth embodiment is shown in FIG. The optical encoder 8 is obtained by modifying the first scale 23 of the optical encoder 6 of the sixth embodiment, and providing a belt-like reflective film 23e on the surface 23a instead of the groove 23c. The reflection film 23e is made of a metal such as aluminum, nickel, or chromium, and has a constant width, is parallel to each other, and is provided at a constant arrangement pitch. The reflective film 23 e serves as a light guide that advances the light from the light source 21 in the direction of the second scale 24.

  The arrangement pitch of the reflective films 23e of the first scale 23 that can be formed by photolithography or printing may be made smaller than the arrangement pitch of the grooves 24c of the second scale 24 formed by mechanical processing or molding. Is possible. In the optical encoder 8, the arrangement pitch of the reflection films 23e and the arrangement pitch of the grooves 24c are set in such a relationship, and the imaging magnification of the lens 25 is set to the ratio of the arrangement pitch of the grooves 24c to the arrangement pitch of the reflection films 23e (> By using the second scale 24 that can be manufactured by molding and has high mass productivity, it is possible to achieve high accuracy that cannot be achieved only by the scale manufactured by molding.

  The configuration of the optical encoder 9 of the ninth embodiment is shown in FIG. The optical encoder 9 modifies both the first scale 23 and the second scale 24 of the optical encoder 6 of the sixth embodiment, and a band-shaped reflective film 23e is formed on the surface 23a of the first scale 23. A band-shaped light shielding film 24 e is provided on the surface 24 a of the second scale 24.

  The arrangement pitch of the reflection film 23e and the light shielding film 24e can be made smaller than the arrangement pitch of the groove 23c and the groove 24c, and the optical encoder 9 is high even if the imaging magnification of the lens 25 is set to 1. Accuracy is obtained. In addition, since the lens 25 forms an image of the light from the surface 23a of the first scale 23 on the surface 24a of the second scale 24, the boundary between the bright part and the dark part on the surface 24a becomes clear. Will be even higher.

  The configuration of the optical encoder 10 of the tenth embodiment is shown in FIG. In the optical encoder 10, the second scale 24 of the optical encoder 8 of the eighth embodiment is extended to form a slope 24f on the surface 24a and a slope 24g on the surface 24b. The inclined surface 24f is located in front of the light source 21, obliquely intersects with the normal line of the light source 21, and illuminates the light from the light source 21 in the vicinity of the extension of the line connecting the optical sensor 22 and the lens 25 in the surface 23a. Point to the site. The inclined surface 24g is substantially orthogonal to the light from the inclined surface 24f and causes the light to travel straight.

  When the light source 21 is a light emitting diode (LED), the light from the light source 21 becomes a divergent light having a large radiation angle, so that the light is incident on the illumination target portion of the surface 24a without providing the inclined surface 24f. However, when a light source 21 that emits divergent light with a relatively small radiation angle or a light source that emits parallel light, such as a laser diode (LD), is used, the light source 21 is disposed toward the illumination target part. Without it, it becomes difficult to guide light to the illumination target part.

  However, when the light from the light source 21 is deflected by the surface 24f as in the present embodiment, it is not necessary to arrange the light source 21 toward the illumination target part, and there are no restrictions on the elements that can be used as the light source 21. . Even when an LED is used as the light source 21, the configuration in which the light from the light source 21 is deflected by the surface 24f is useful because more light can be guided to the illumination target part.

  In order to provide the inclined surface 24f and the inclined surface 24g, it is not always necessary to extend the second scale 24, and another member having an inclined surface, for example, a prism may be arranged side by side with the second scale 24. .

  The configuration of the optical encoder 11 of the eleventh embodiment is shown in FIG. This optical encoder 11 is obtained by extending a lens 25 and providing a diffraction grating 25f on the surface of the extended portion. The diffraction grating 25f faces the light source 21 and directs the light from the light source 21 to a portion to be illuminated on the surface 23a near the extension of the line connecting the optical sensor 22 and the lens 25. The diffraction grating 25f is composed of fine band-shaped irregularities, and is set so that the arrangement pitch of the irregularities gradually changes in order to increase the diffraction efficiency in one direction.

  In the present embodiment, the second scale 24 is also extended to have a portion directly facing the light source 21, but this is for convenience of fixing to the substrate 20, and the light of the diffraction grating 25f is transmitted. It has nothing to do with deflection.

  The configuration of the optical encoder 12 of the twelfth embodiment is shown in FIG. The optical encoder 12 uses an anamorphic lens having different optical powers in two orthogonal directions as the lens 25. The power of the lens 25 is maximum in the arrangement direction of the reflection film 23e of the first scale 23 (the light shielding film 24e of the second scale 24) and is minimum in the direction perpendicular thereto.

  In order to clarify the boundary between the bright part and the dark part on the surface 24a of the second scale 24 and improve the detection accuracy, the boundary extending in the direction perpendicular to the arrangement direction of the reflective film 23e and the light shielding film 24e is clear. Therefore, the lens 25 may have an imaging function only in the arrangement direction of the reflection film 23e and the light shielding film 24e. The optical encoder 12 takes this point into consideration. The lens 25 may be a cylindrical lens having no power in the direction perpendicular to the arrangement direction of the reflection film 23e and the light shielding film 24e.

  When the lens 25 is a cylindrical lens, the width of the second scale 24 (the size in the direction perpendicular to the paper surface of FIG. 19) needs to be equal to or greater than the width of the first scale 23. If the lens 25 is an anamorphic lens having a certain level of power in the direction perpendicular to the arrangement direction of the reflection film 23e and the light shielding film 24e, the width of the second scale 24 may be made smaller than the width of the first scale 23. it can.

  The configuration of the optical encoder 13 of the thirteenth embodiment is shown in FIG. The optical encoder 13 includes an annular flat plate as the first scale 23. As shown in FIG. 20B, the optical encoder 13 has a light source on the surface close to the light source 21 of the first scale 23. Reflective films 23e that reflect the light from 21 are arranged radially.

  The configuration of the optical encoder 14 of the fourteenth embodiment is shown in FIG. The optical encoder 14 includes a cylindrical one as the first scale 23, and a reflection film 23 e that reflects light from the light source 21 is parallel to the cylindrical axis on the outer surface of the first scale 23. It is arranged.

  The optical encoders 13 and 14 are used to detect the position of a movable member that rotates. In any of the optical encoders 13 and 14, the arrangement direction of the reflective films 23 e of the first scale 23 is the circumferential direction as a whole, but the second scale 24 is close to the second scale 24. The groove 24c is substantially parallel to the arrangement direction of the grooves 24c, and the moving direction is also substantially parallel to the arrangement direction of the grooves 24c.

  In the optical encoder 14, the distance from the region receiving the light from the light source 21 on the surface of the first scale 23 to the surface 24 a of the second scale 24 is not constant. However, the entire region is within the depth of field of the lens 25, and the bright and dark portions on the surface 24a of the second scale 24 are clear.

  The configuration of the optical encoder 15 of the fifteenth embodiment is shown in FIG. FIG. 22 is a sectional view in a single longitudinal section. In the optical encoder 15 of the present embodiment, the direction connecting the light source 21 and the optical sensor 22 is the arrangement direction of the grooves 23c of the first scale 23 and the second direction. This is parallel to the arrangement direction of the light shielding films 24e of the scale 24.

  A triangular prism 26 is arranged on the second scale 24 so as to face the light source 21. The triangular prism 26 transmits light from the light source 21 to the light source 21 on the surface 23 a of the first scale 23. It is made to face to the part which opposes between optical sensors 22. The light incident on the surface 23a of the first scale 23 is slightly inclined in the arrangement direction of the grooves 23c, and the groove 23c has an asymmetric shape with respect to the arrangement direction so that the light can be totally reflected.

  In the optical encoder 15 of the present embodiment, the setting of the groove 23c is slightly complicated, but the overall configuration can be small (small in the direction perpendicular to the paper surface of FIG. 22).

  The configuration of the optical encoder 16 of the sixteenth embodiment is shown in FIG. In the optical encoder 16, the first scale 23 and the second scale 24 are not parallel, and the extended surfaces of the surfaces 23a and 24a intersect each other. The lens 25 is arranged so that a plane passing through the center and perpendicular to the optical axis includes a straight line formed by intersecting the extended surfaces of the surface 23a and the surface 24a. Therefore, Scheinproof's law is established, and light from the surface 23 a (reflection film 23 e) of the first scale 23 forms an image on the surface 24 a of the second scale 24.

  However, the pitch between the bright part and the dark part on the surface 24 a is not constant, and gradually increases as the distance from the lens 25 increases. For this reason, the arrangement pitch of the light shielding films 24e provided on the surface 24a is set to coincide with the pitch of the bright part and the dark part formed on the surface 24a.

  The configuration of the optical encoder 17 of the seventeenth embodiment is shown in FIG. In the optical encoder 17, the light source 21 is disposed at a position facing the optical sensor 22, and the first scale 23, the lens 25, and the second scale 24 are positioned therebetween. A groove 23c is formed on the surface 23a of the first scale 23 far from the light source 21 (closer to the optical sensor 22), and the groove 24c is also formed on the surface 24a of the second scale 24 closer to the optical sensor 22. 24c is formed.

  In this configuration, with respect to the first scale 23, the light guide unit that causes the light from the light source 21 to travel in the direction of the second scale 24 is not the groove 23c but a portion between the grooves 23c and 23c. In addition, it is good also as a structure provided with the light shielding film instead of the groove | channel 23c, and good also as a structure provided with the light shielding film 24e instead of the groove | channel 24c.

  The configuration of the optical encoder 18 of the eighteenth embodiment is shown in FIG. The optical encoder 18 fixes the first scale 23 together with the lens 25 to the substrate 20 on which the light source 21 and the optical sensor 22 are provided, and these are used as one unit, and the second scale 24 is movable. It is. The second scale 24 is attached to a movable member that is a position detection target.

  The principle of detecting the position of the second scale 24 in the optical encoder 18 is the same as the principle of detecting the position of the first scale 23 in the optical encoder 1 of the first embodiment. As is apparent from the difference in configuration between the optical encoder 18 and the optical encoder 1, the first scale 23 is fixed in each of the optical encoders 2 to 17 in the second to seventeenth embodiments described above. Two scales 24 can be movable.

  FIG. 26 schematically shows the configuration of an imaging apparatus 19 that is the nineteenth embodiment. The image pickup device 19 converts an image pickup device 32 that takes an image by converting light into an electrical signal, an image pickup optical system 31 that forms an image of light from a shooting target on the image pickup device 32, and outputs an output signal from the image pickup device 32 to Image processing unit 33 for generating image data representing a captured image by performing various processes such as conversion, white balance adjustment, and γ correction, a recording unit 34 for recording the generated image data on a recording medium, and an imaging optical system 31 includes a lens driving unit 35 that drives a movable lens for focus adjustment and zooming included in the lens 31, an optical encoder 36 that detects the position of the movable lens, and a control unit 37.

  The control unit 37 is composed of a microcomputer and controls the operations of the image sensor 32, the image processing unit 33, and the recording unit 34. The control unit 37 also adjusts the position of the movable lens via the lens driving unit 35 while detecting the position of the movable lens included in the imaging optical system 31 based on the output of the optical encoder 36.

  FIG. 27 shows the movable lens, the lens driving unit 35, and the optical encoder 36 of the imaging optical system 31. The imaging optical system 31 has two movable lenses 41 and 42, and the movable lenses 41 and 42 are fixed to lens holding frames 43 and 44, respectively.

  A protrusion having a groove 43a cut out in a V shape is provided on the upper portion of the lens holding frame 43, and a protrusion having a groove 43b having parallel wall surfaces is provided on the lower portion. A leaf spring 43 c is attached to the side surface of the lens holding frame 43. The leaf spring 43c is fixed to the lens holding frame 43 below the groove 43a and reaches above the groove 43a. A drive shaft 45 that transmits a driving force from the lens drive unit 35 is inserted between the groove 43 a and the plate spring 43 c, and the drive shaft 45 contacts the wall surface of the groove 43 a and the plate spring 43. The drive shaft 43 is parallel to the optical axis of the imaging optical system 31.

  A guide shaft 47 for guiding the movement of the lens holding frame 43 is inserted into the groove 43b, and the guide shaft 47 is in contact with the wall surface of the groove 43b. The guide shaft 47 is also parallel to the optical axis of the imaging optical system 31.

  The lens holding frame 44 has the same configuration. However, only the V-shaped groove 44a, the leaf spring 44c, and the drive shaft 46 are shown here, and the groove corresponding to the groove 43b and the guide shaft corresponding to the guide shaft 47 are not shown.

  The lens driving unit 35 includes two actuators 48 and 49 for individually driving the lens holding frames 43 and 44. Here, in order to reduce the size of the configuration, as the actuators 48 and 49, piezoelectric elements that expand and contract according to the applied voltage are used.

  One end of each of the actuators 48 and 49 is fixed to the base, and the other end is fixed to the drive shafts 45 and 46, respectively. The drive shafts 45 and 46 move in the respective axial directions according to the expansion and contraction of the actuators 48 and 49. The lens holding frame 43 in which the groove 43a and the leaf spring 43c are merely in contact with the drive shaft 45 follows the movement of the drive shaft 45 by frictional force when the drive shaft 45 moves at a relatively low speed. On the other hand, when the drive shaft 45 moves at a relatively high speed, the drive shaft 45, the groove 43a, and the leaf spring 43c slip, and the lens holding frame 43 does not move.

  Therefore, by applying a sawtooth voltage to the actuator 48, the lens holding frame 43 can be moved in one direction along the optical axis, and an applied voltage having a reverse waveform direction is applied to the actuator 48. Thus, the lens holding frame 43 can be moved in the reverse direction. During movement, the lens holding frame 43 does not rotate around the drive shaft 45 because the groove 43 b is in contact with the guide shaft 47. The driving of the lens holding frame 44 is performed in the same manner.

  The optical encoder 36 is provided for each of the two movable lenses 41 and 42. Here, as the optical encoder 36, the optical encoder 6 of the sixth embodiment in which the lens 25 and the second scale 24 are integrated is used, and the first scale 23 is attached to the lens holding frames 43 and 44. It has been. For the optical encoder 32 for the movable lens 41, only the first scale 23 is shown.

  Although the imaging device 19 having such a configuration is small, it can detect the positions of the movable lenses 41 and 42 with high accuracy. Therefore, for example, it is suitable for a mobile phone having an imaging function. Here, the configuration including the optical encoder 6 of the sixth embodiment is taken as an example, but other than the optical encoders 13 and 14 of the thirteenth and fourteenth embodiments for detecting rotational motion, other configurations are provided. It is also possible to include the optical encoder of the embodiment.

  In the imaging device 19, since the moving direction of the lenses 41 and 42 can be determined from the voltages applied to the actuators 48 and 49, it is not necessary to determine the moving direction with the optical encoder 36. However, if the optical encoder 3 of the third embodiment is provided, the detection accuracy can be further increased.

  In the present embodiment, the movement of the movable lenses 41 and 42 in the optical axis direction is detected. However, in an imaging apparatus that moves some lenses in a direction perpendicular to the optical axis for blur correction. The position of the correction lens can be detected by the optical encoder of the present invention. Further, the optical encoder of the present invention is not limited to an imaging device, and can be employed in any optical device having a movable optical member.

The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 1st Embodiment. The perspective view which shows the structure of the optical encoder of 1st Embodiment. The figure which shows a mode that the intensity | strength of the output signal of an optical sensor fluctuates with the movement of a 1st scale. Sectional drawing for demonstrating the setting of the slope of the groove | channel provided in the scale. The figure which shows the image of the bright part and dark part which are formed on the surface of a 2nd scale with a lens. The longitudinal cross-sectional view of the 1st scale of the optical encoder of 2nd Embodiment. The perspective view which shows the structure of the optical encoder of 3rd Embodiment. The front view which shows the surface of the 2nd scale of the optical encoder of 3rd Embodiment. The figure which shows a mode that the intensity | strength of the output signal of the optical sensor in the optical encoder of 3rd Embodiment fluctuates with the movement of a 1st scale. The figure which shows the Lissajous waveform obtained from the output signal of FIG. The longitudinal cross-sectional view (a) and front view (b) of the lens of the optical encoder of 4th Embodiment. The longitudinal cross-sectional view (a) and front view (b) of the lens of the optical encoder of 5th Embodiment. The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 6th Embodiment. The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 7th Embodiment. The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 8th Embodiment. The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 9th Embodiment. The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 10th Embodiment. The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 11th Embodiment. The combination longitudinal cross-sectional view which shows the structure of the optical encoder of 12th Embodiment. The perspective view (a) which shows the structure of the optical encoder of 13th Embodiment, and the front view (b) of the 1st scale. The perspective view which shows the structure of the optical encoder of 14th Embodiment. The longitudinal cross-sectional view which shows the structure of the optical encoder of 15th Embodiment. The longitudinal cross-sectional view which shows the structure of the optical encoder of 16th Embodiment. The longitudinal cross-sectional view which shows the structure of the optical encoder of 17th Embodiment. The perspective view which shows the structure of the optical encoder of 18th Embodiment. FIG. 25 is a block diagram schematically illustrating the configuration of an imaging device according to a nineteenth embodiment. The perspective view which shows the principal part of the imaging device of 19th Embodiment. The longitudinal cross-sectional view which shows the structure of the conventional optical encoder.

Explanation of symbols

1-18 Optical encoder 19 Imaging device 20 Substrate 21 Light source 22 Optical sensor 23 First scale 23a Scale surface 23b Scale surface 23c Groove 23d ２３ 23e Reflective film 24 Second scale 24a Scale surface 24b Scale surface 24c Groove 24e Light-shielding film 24f Slope 24g Slope 24A First part 24B Second part 25 Lens 25f Diffraction grating 26 Triangular prism 31 Imaging optical system 32 Imaging element 33 Image processing part 34 Recording part 35 Lens drive part 36 Optical encoder 37 Control part 41, 42 Movable lens 43, 44 Lens holding frame 43a, 44a Groove 43b Groove 43c, 44c Leaf spring 45, 46 Drive shaft 47 Guide shaft 48, 49 Actuator

Claims (7)

A light source that emits light, a first scale that has a plurality of light guides that are spaced apart to advance light from the light source in a predetermined direction, and light from the light guide unit of the first scale is advanced in a predetermined direction A second scale having a plurality of light guides arranged apart from each other, and an optical sensor for detecting the amount of light received by receiving light from the light guides of the second scale. One of the two scales is movable in the arrangement direction of the light guides, and the optical encoder detects the position of the scale based on the change in the amount of light received by the optical sensor due to the movement of the scale.
An optical encoder comprising: an imaging optical system that forms an image of light from the light guide of the first scale on the second scale between the first scale and the second scale.   The optical encoder according to claim 1, wherein the non-movable scale of the first scale and the second scale, the light source, and the optical sensor are fixed to the same member.   The optical system according to claim 1, further comprising a deflection optical system that bends an optical path of light from the light source and directs light from the light source toward the first scale between the light source and the first scale. Type encoder.   2. The optical encoder according to claim 1, wherein the imaging optical system is one of a Fresnel lens and a diffractive lens.   2. The optical encoder according to claim 1, wherein the optical power of the imaging optical system is different between a direction parallel to an arrangement direction of the light guide portions of the second scale and a direction perpendicular thereto.   2. The optical type according to claim 1, wherein the non-movable scale of the first scale and the second scale and the imaging optical system are provided on opposing surfaces of the same transparent member. Encoder. In an optical device including a movable optical member,
The optical encoder according to any one of claims 1 to 6 is provided in a form in which a movable scale of the first scale and the second scale is attached to a movable optical member. An optical apparatus, wherein the position of a movable optical member is detected by an encoder.

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