JP5011799B2 - Optical encoder - Google Patents

Description

  The present invention relates to an optical encoder including a light source, a reflecting member, and a light receiving element. For example, it is used by being coupled to a rotating shaft of a servo motor and a driving portion of a linear motor.

  Conventionally, reflecting members used in optical encoders have a high reflectance over a wide wavelength range from ultraviolet light to visible light to infrared light by depositing a metal film such as aluminum or chromium on the surface of glass, resin material, etc. have. As an example of disclosure of an optical encoder using a reflecting member, there are, for example, Patent Document 1 and Patent Document 2. Both Patent Document 1 and Patent Document 2 use a concave mirror as a collimating lens for collimating light rays from a light source. In Patent Document 1, the material of the concave mirror is aluminum, and in Patent Document 2, there is no description about the reflective film material of the concave mirror, and it is common sense to use a reflective member on which a metal film such as aluminum is deposited. It means that

  In addition, as a code plate for an optical encoder, two types, a transmission type and a reflection type, are generally well known. The transmission type code plate is composed of a non-transmission portion obtained by vapor-depositing a metal such as chromium on a transparent member such as glass or optical resin, and a non-evaporation transmission portion. A light beam emitted from a light source is applied to a code plate, and transmitted light encoded by the code plate is detected by a light receiving element. In particular, a transmission code plate of an optical encoder that requires high accuracy is generally known in which chromium is vapor-deposited and patterned by etching.

  On the other hand, the reflective code plate is composed of a reflective part in which a metal film such as chromium is deposited on glass or a resin material and a non-reflective part that transmits or absorbs light. A light beam emitted from a light source is irradiated onto a code plate, and reflected light encoded by the code plate is detected by a light receiving element. As an example of disclosure of an optical encoder using a reflective code plate, there is Patent Document 3, for example. A light emitted from an LED (Light Emitting Diode) light source is applied to an incremental pattern and an absolute pattern provided on a scale disk, and the reflected light is detected by a light receiving element array. According to the embodiment of Patent Document 3, the reflection pattern is formed by vapor-depositing chromium or the like on the surface of the scale disk. There are other optical encoders that use a reflective code plate, but it is common knowledge that the reflective pattern is formed by vapor-depositing a metal film such as chromium or forming a slit hole in the metal plate itself. Are known.

  In addition, as a light source used for signal detection of the optical encoder, an infrared LED or LD (laser diode) is mainly used, and accordingly, a light receiving element for signal detection has a wavelength in the vicinity of the 800 to 1000 nm region. Those having high sensitivity to infrared light are used.

Japanese Patent Laid-Open No. 7-151565 (FIG. 3) Japanese Patent Laid-Open No. 7-55506 (FIG. 1) Japanese Patent Laying-Open No. 2005-121593 (FIG. 1)

  Reflective members deposited with a metal film used in conventional encoders have high reflectivity for infrared light necessary for encoder signal detection, but for visible light that is not particularly necessary for encoder signal detection. Also have a high reflectivity. Therefore, the surface metal film exists even when an opaque material is used for the base material on which the reflective film is deposited, and even when a transparent material such as glass or optical resin is used for the base material. As a result, the reflecting surface becomes opaque, and the back surface of the reflecting member and the members on the back side of the reflecting member cannot be visually confirmed. When a reflective member with a metal vapor deposition film is used for an optical encoder, the reflective surface (metal vapor deposition surface) hinders visual observation, and the member behind the reflective member cannot be seen. There was a problem that assembly of the encoder could not be easily performed, and it took time to assemble.

Red optical encoder according to the present invention comprises a light source for emitting infrared light, a reflecting member for transmitting therethrough at least one of the reflected visible light and ultraviolet light and infrared light from the light source, reflected by the reflecting member It is characterized by comprising a transmissive code plate irradiated with external light rays and a light receiving element for receiving infrared light transmitted through the transmissive code plate .

Red optical encoder according to the present invention comprises a light source for emitting infrared light, a reflecting member for transmitting therethrough at least one of the reflected visible light and ultraviolet light and infrared light from the light source, reflected by the reflecting member Since the transmission type code plate irradiated with the external light beam and the light receiving element that receives the infrared ray transmitted through the transmission type code plate are provided, the optical encoder can be easily assembled with high accuracy.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a schematic structure of an optical encoder according to the first embodiment. A light beam 104 emitted from an infrared LED 1 as a light source is reflected by a concave mirror 101 including a reflective film 102 having a reflective member assembled on a rotating shaft 2 such as a motor via a mirror receiver 103. . The reflected light beam 105 is collimated by the concave mirror 101 to become a substantially parallel light beam, and is irradiated over substantially the entire circumference of the scale disk 3. A slit 6 composed of a transmission part and a non-transmission part is provided on the scale disk 3, and a light beam transmitted through the scale disk 3 is encoded by the slit 6 and is provided on the light receiving part 4. 5 is detected.

  In general, when a light ray hits an object, it will show one of the reflection, absorption, and transmission modes, or a combination thereof (combination at a fixed ratio). In particular, in the case of real objects, most of them are a combination of reflection, absorption, and transmission, and the thing with the largest ratio is captured and referred to as reflection, absorption, and transmission. Even in this specification, even if it is simply referred to as reflection, transmission, absorption, it does not deny that other aspects are included, but the one with the highest reflectance, transmittance, and absorption rate. These are called reflection, transmission and absorption, respectively. Therefore, even when simply referred to as reflection or transmission, it includes absorption of a part of the light beam, and indicates that the reflectance or transmittance is high. This is common throughout the entire specification.

  In the concave mirror 101, a substance such as a dielectric multilayer film is deposited on a base material formed by optical resin molding or glass cutting. A reflective member is formed by vapor-depositing this dielectric multilayer film. The concave mirror 101 has a high reflectance with respect to infrared light, which is the wavelength of the light source, but has a low reflectance in the wavelength region of visible light and ultraviolet light.

  A combination of various dielectric films can be considered as the dielectric multilayer film, but it reflects or absorbs light in the wavelength region necessary for signal detection, and the light whose wavelength region is not used for signal detection (required for signal detection The reflection film 102 transmits all or a part of light in a wavelength region other than the wavelength region. That is, the concave mirror 101 reflects or absorbs light when it is infrared light, and transmits light when it is visible light or ultraviolet light.

  The reflecting member of the present invention will be described. In an optical encoder provided with a reflecting member in addition to a light source for detection and a light receiving element, a reflecting member deposited with a substance such as a dielectric multilayer film is used instead of the reflecting member deposited with a metal film. The present invention. For example, the reflecting member has a high reflectance (for example, 70% or more) for infrared light (wavelength longer than 800 nm) necessary for encoder signal detection, and the visible light necessary for visual inspection is low. By having high reflectivity (for example, 50% or less) and high transmittance (for example, 10% or more), the relative position of the mirror with respect to other members can be easily discerned visually, simplifying the assembly process that requires precision. It can be made.

  Here, the reason why it has a high reflectivity with respect to infrared light is mainly because the light source used for the encoder is infrared light, and the wavelength region to be reflected is actually a dielectric material or the like. It is possible to design freely by changing the film thickness of the multilayer film. For this reason, not only infrared light but also a reflecting member that reflects, for example, light having a wavelength of 700 nm but transmits other light can be used. In addition, it has been described that it has a high transmittance with respect to visible light, but when it is imaged using an imaging device such as a CCD, it is opaque to visible light but transparent to infrared light. Visual observation is possible through camera images. That is, the object of the present invention can be achieved by using a reflective member that reflects light in the wavelength region necessary for encoder signal detection and transmits light in the wavelength region necessary for visual observation including imaging by the image sensor.

  Specifically, in the first embodiment, the reflecting member of the concave mirror 101 reflects a light beam in a wavelength region necessary for signal detection and transmits a light beam outside the wavelength region necessary for signal detection. The concave mirror 101 reflects in the case of infrared light and transmits in the case of visible light.

  For this reason, since light rays from ultraviolet light to visible light pass through the concave mirror 101, the upper surface of the mirror receiver 103 can be observed visually from above the concave mirror 101. The upper surface of the mirror receiver 103 is marked for alignment. When assembling the concave mirror 101, the alignment mark on the upper surface of the mirror receiver 103 is observed through the concave mirror 101 so that the optical axis center of the concave mirror 101 is positioned on the rotation center 7 of the rotation axis 2. The position can be easily adjusted with accuracy.

  In addition, since it is necessary to assemble optical parts of a high-precision optical encoder with high precision, a method of assembling using a UV (Ultra Violet) ultraviolet curable adhesive 106 is effective. After applying a UV light curable adhesive 106 to the upper part of the mirror receiver 103 and mounting the concave mirror 101 thereon, adjusting the position so that the optical axis center of the concave mirror 101 is on the rotation center 7, The concave mirror 101 can be easily assembled with high positional accuracy by irradiating UV light and curing the adhesive 106 to fix the assembly. When the UV light curing adhesive 106 is used, the concave mirror 101 becomes a reflecting member that reflects when it is infrared light and transmits when the light beam is visible light and ultraviolet light. Yes.

  When a metal film is used as a reflection film during the above assembly, the metal film hinders UV light irradiation, and a portion that is not irradiated, that is, an uncured portion is generated or is completely cured. There is a concern that it takes more time than the case where the transmission lens is used. In contrast, when an ultraviolet light curable adhesive is used for assembling the reflective member or the light receiving element 5, the reflective film 102 has a property of transmitting light having a wavelength from visible light to ultraviolet light. When the above assembling method is carried out, for example, even if the UV light is irradiated from above the concave mirror 107, a shadow is not formed by the reflective film 102, so that the irradiation can be performed efficiently. For this reason, it is possible to increase the efficiency by shortening the curing time, and it is possible to perform highly reliable assembly by reducing the uncured portion.

  Here, an infrared LED is used as a light source, and the reflection film 102 has a high reflectance with respect to infrared light and a reflection member that transmits from ultraviolet light to visible light is described. . In addition, a structure using an adhesive that cures when irradiated with UV light has been described. However, the configuration is not limited to this, and the object of the present invention can be achieved even in the case of using an adhesive that is cured by irradiation with visible light. In other words, if a reflecting member is used that reflects light in the wavelength region necessary for encoder signal detection and transmits the wavelength region necessary for visual observation including imaging by the image sensor or the wavelength region necessary for curing of the adhesive The object of the present invention is achieved.

  In addition, the use of the concave mirror 101 is not limited to the configuration of the present embodiment, but also in an optical encoder using a reflecting member that functions as a lens that plays a role of condensing, diverging, collimating light rays. In addition, it is possible to easily perform assembly with high accuracy over the entire optical encoder that requires the position adjustment of the reflecting member or the members around the reflecting member.

Embodiment 2. FIG.
FIG. 2 is a diagram showing a schematic structure of the optical encoder according to the second embodiment, and is a schematic diagram of an optical rotary encoder using a transmission scale disk. The light beam emitted from the infrared LED 1 that is a light source is applied to the scale disk 3, and the light beam that has passed through the scale disk 3 is detected by the light receiving element 5 provided on the light receiving unit 4. The scale disk 3 that encodes the transmitted light includes a transmission unit 201 that transmits infrared light, which is a light beam in a wavelength region necessary for signal detection, and a non-transmission unit 202 that blocks light. In the drawings, the same reference numerals denote the same or corresponding parts, and this is common throughout the entire specification. Further, the description of the constituent elements appearing in the whole specification is merely an example and is not limited to these descriptions.

  The scale disk 3 is formed by vapor-depositing a material such as a dielectric multilayer film on a disk-shaped substrate formed of optical resin molding or glass material, and serves as a reflective member. . The non-transmissive portion 202 has a high reflectance with respect to infrared light that is the wavelength of the infrared LED 1. That is, the light beam necessary for signal detection is cut off without being transmitted, but the reflectance in the wavelength region of visible light and ultraviolet light is low, and light rays from ultraviolet light to visible light are transmitted. Therefore, for example, the position of the infrared LED 1 of the light source can be visually observed from the right side of FIG. 2 (side with the light receiving unit 5) through the scale disc 3, and conversely, the left side of FIG. 2 (side with the light source 1). The position of the light receiving element 4 can be visually observed through the scale disk 3.

  In general, when forming a scale disk, almost all the surface is made a non-transmission portion so that extra light rays are not incident on the light receiving element except for portions where light rays need to be transmitted (so-called track portions). It is normal. For this reason, in the conventional scale disk subjected to chromium deposition or the like, for example, when visually observing from the light receiving element side, the position of the member (light source 1 or rotating shaft 2 in FIG. 2) on the opposite side of the scale disk However, when the scale disk 3 according to the present invention is applied, the position of the light source and the rotating shaft 2 can be visually confirmed. Therefore, the relative position of the scale disk 3 with respect to the rotating shaft 2 and It becomes easy to adjust the position of the light source 1 with respect to the scale disk 3, and it can be expected to improve the assembly accuracy and shorten the assembly time.

FIG. 3 is a diagram illustrating a schematic structure of the optical encoder according to the second embodiment, and is a diagram illustrating a schematic configuration of a scale disk including a fastening structure with a rotation shaft formed by resin molding.
FIG. 3A is a top view of the scale disk, and FIG. 3B shows a cross-sectional view taken along the alternate long and short dash line in FIG. When creating the scale disk 3 by resin molding, it is possible to easily create a structure that is fastened in such a manner that the rotary shaft 2 is inserted into the scale disk 3. When the rotating shaft 2 is assembled to the fastening portion 204 provided in the scale disc 3, the rotating shaft may be press-fitted and assembled without a gap between the fastening portion 204 and the rotating shaft 2 in some cases. However, in the case of a high-precision optical encoder, since the scale disk 3 needs to be assembled with high accuracy with respect to the rotation center 7 of the rotation shaft 2, there is a gap between the fastening portion 204 and the rotation shaft 2. A method is often used in which the scale disk 3 is fixed by means such as adhesion after leaving the space to adjust the eccentricity of the scale disk 3.

  At this time, a method of assembling using a UV light curable adhesive as an adhesive is effective. The UV light adhesive 203 is applied in advance to the inside of the rotating shaft 2 or the fastening portion 3, the rotating shaft 2 is inserted into the fastening portion 204, the eccentricity adjustment of the scale disk 3 with respect to the rotation center 7 is performed, and the UV light is then applied. By irradiating and curing the adhesive 203, the scale disc 3 can be assembled with high positional accuracy.

  When assembling, if a metal film such as chromium vapor deposition is used for the non-transmission part, the metal film hinders the UV light irradiation. In FIG. 3, the irradiation UV light is irradiated from above the scale disk 3. Even if the adhesive 203 is not irradiated with light and it is necessary to irradiate light from the side of the scale disk 3, it takes a long time to cure, or a portion that is not irradiated, that is, an uncured portion is generated. Is concerned.

  On the other hand, by applying the reflective member of the present invention, the non-transmissive portion 202 that becomes a reflective film has a property of transmitting from visible light to ultraviolet light, so when performing the above assembly method, For example, even if UV light is irradiated from above the scale disk 3, it is not shielded by the reflective film 202, so that light rays are efficiently irradiated, enabling high efficiency by shortening the curing time and reducing uncured portions. Highly reliable assembly is expected.

  In addition, the reflecting member used as the non-transmissive portion 202 in this embodiment does not necessarily have a high reflectance, and a member having a large absorption coefficient for the wavelength region necessary for encoder detection can be applied. This can be freely designed by changing the material and film thickness of the dielectric multilayer film to be deposited, and has a high shielding property against light from the light source by having a high reflectance or a large absorption coefficient.

  In this embodiment, as an example, an infrared LED is used as a light source, and the non-transmissive portion 202 has a high blocking property against infrared light and transmits from ultraviolet light to visible light. Although the configuration using the absorbing member) has been described, the configuration is not limited to this. Reflection member (or absorption) that reflects or absorbs light in the wavelength region necessary for encoder signal detection and transmits the wavelength region necessary for visual observation including imaging by the image sensor or the wavelength region necessary for curing of the adhesive. If the member is used, the object of the present invention can be achieved.

  The effectiveness of the present invention is not limited to the configuration of the present embodiment, and can be applied to various optical rotary encoders that can achieve the above object.

Embodiment 3 FIG.
FIG. 4 is a diagram showing a schematic structure of the optical encoder according to the third embodiment, and is a perspective view showing an outline of the optical linear encoder using a transmission linear scale. A light beam emitted from the infrared LED 1 as a light source is applied to the linear scale 300, and the light beam transmitted through the linear scale 300 is detected by the light receiving element 5 provided on the light receiving unit 4. The linear scale 300 that encodes transmitted light includes a transmissive part 301 that transmits infrared rays and a non-transmissive part 302 that blocks light. The linear scale 300 serves as a scale by moving in the direction of the left and right arrows shown in the drawing, and is a transmissive code plate. Although FIG. 4 describes a configuration in which the scale moves, the present embodiment can be applied to a configuration in which an optical head in which a light source and a light receiving unit are integrated moves.

  The linear scale 300 is formed with a reflective member that can be formed by vapor-depositing a material such as a dielectric multilayer film that becomes the non-transmissive portion 302 on a plate-like base material formed of optical resin molding or glass material. ing. The non-transmission part 302 has a high reflectance with respect to the infrared light which is the wavelength of the light source LED1. Infrared rays are blocked without being transmitted, but reflectivity in the wavelength region of visible light and ultraviolet light is low, and rays from ultraviolet light to visible light are transmitted. For example, the position of the light receiving unit 4 can be visually observed through the scale 300 from the near side (the side with the light source 1) in FIG. 4, and conversely through the scale 300 from the back side (the side with the light receiving unit 4) in FIG. The position of the infrared LED 1 as the light source can be observed.

  In general, when a linear scale is formed, the entire surface is often made a non-transmissive portion so that extra light does not enter the light receiving element except for a portion where light rays need to be transmitted (so-called track portion). For this reason, in the case of performing chromium vapor deposition or the like as in the prior art, in an encoder using a linear scale, for example, when visually observing from the light receiving element side, a member on the opposite side of the linear scale (light source 1 in FIG. 4). ) Cannot be confirmed. On the other hand, when the linear scale 300 according to the present invention is applied, the position of the light source 1 can be visually confirmed, and conversely, the position of the light receiving element 5 can be confirmed through the linear scale 300 from the light source 1 side. Therefore, the relative position of the linear scale 300 with respect to the linear drive unit and the position adjustment of the light receiving element 5 and the light source 1 with respect to the linear scale 300 are facilitated, and the assembly accuracy can be improved and the assembly time can be shortened.

  Further, when assembling the linear scale 300 to the guide, a method of assembling using a UV light curable adhesive as an adhesive is effective. In the case of this embodiment, a UV scale adhesive is applied in advance to the bonding location of the guide, and the linear scale 300 is arranged, and the linear scale 300 comes to an appropriate position with respect to the linear scale or the driving direction of the optical head. After the adjustment, the linear scale 300 can be assembled with high positional accuracy by irradiating UV light and curing the adhesive.

  When a metal film is used for the non-transmissive portion 302 in the above assembly, the metal film hinders UV light irradiation, and a portion that is not irradiated, that is, an uncured portion is generated or is necessary for complete curing. It takes more time than with a transmissive lens. On the other hand, by using the reflecting member of the present invention, the non-transmissive portion 302 has a property of transmitting from visible light to ultraviolet light. Since the shadow by the transmissive part 302 cannot be formed, it is possible to achieve high efficiency by efficiently irradiating and shortening the curing time, and high reliability assembly by reducing the uncured part can be expected.

  In addition, the reflecting member used as the non-transmissive portion 302 in the present embodiment does not necessarily have a high reflectance, and a member having a large absorption coefficient can be applied to the wavelength region necessary for encoder detection. . This can be freely designed by changing the material and film thickness of the dielectric multilayer film to be deposited, and has a high blocking property against the light from the light source 1 by having a high reflectance or a large absorption coefficient. become.

  In this embodiment, an infrared LED 1 is used as a light source as an example, and the non-transmissive portion 302 has a high shielding property against infrared light, and is a reflective member (or absorbing member) that transmits ultraviolet light to visible light. Although the configuration using the member is described, the configuration is not limited to this. Reflective member (or absorber) that reflects or absorbs light in the wavelength region necessary for encoder signal detection and transmits the wavelength region necessary for visual observation including imaging by the image sensor or the wavelength region necessary for curing of the adhesive. If the member is used, the object of the present invention can be achieved. Further, the effectiveness of the present invention is not limited to the configuration of the present embodiment, and can be applied to various optical linear encoders that can achieve the above object.

Embodiment 4 FIG.
FIG. 5 is a diagram showing a schematic structure of an optical encoder according to Embodiment 4, and is a side view showing an outline of a rotary encoder using a reflective scale disk. Infrared rays emitted from the infrared LED 1 serving as a light source are applied to the reflective scale disk 400, and the light rays reflected by the scale disc 400 are detected by the light receiving element 5 provided on the light receiving unit 4. . A reflective scale disk 400 that encodes reflected light includes a reflective portion 402 that reflects infrared rays and a non-reflective portion 401 that transmits or absorbs infrared rays.

  The reflective scale disk 400 is formed by depositing a material such as a dielectric multilayer film on the disk-shaped base material formed of optical resin molding or glass material by the reflective portion 402 being a reflective member. Yes. It is the scale disk 400 provided with the rotating shaft 2 and fastening structure formed by resin molding. Although the reflection part 402 has a high reflectance with respect to the infrared light which is the wavelength of the light source LED 1, the reflectance in the wavelength region of visible light or ultraviolet light is low, and light rays from ultraviolet light to visible light are transmitted. Therefore, for example, the position of the rotating shaft 2 can be visually observed through the scale disk 400 from the upper side of FIG. 5 (side with the light receiving unit 4), and conversely the scale from the lower side of FIG. 5 (side with the rotating shaft 2). The position of the light receiving element 5 can be visually observed through the disc 3.

  In general, when a scale disk is formed, almost the entire surface other than a portion where a light beam needs to be reflected (a so-called track portion) is not reflected on the light receiving element (that is, a transmissive portion or a transparent portion). Absorbing part). For this reason, even when the non-reflective part is a transmissive part, the conventional reflective scale disk subjected to chromium vapor deposition or the like is opposite to the scale disk when visually observed from the light receiving element side, for example. The position of the member on the side (rotating shaft 2 in FIG. 5) cannot be confirmed. On the other hand, when the scale disk 400 according to the present invention is applied, the position of the rotating shaft 2 can be visually confirmed by using the non-reflecting portion 401 as a transmitting portion. The relative position of the plate 400 can be easily adjusted, and the assembly accuracy can be improved and the assembly time can be shortened.

  In addition, a member that has a large absorption coefficient with respect to the wavelength region necessary for encoder detection and transmits light from ultraviolet light to visible light can be applied to the non-reflecting part 401. This can be achieved by applying a member that is freely designed to have a large absorption coefficient in the required wavelength region with a dielectric multilayer film having a material or film pressure different from that of the reflecting portion. . Therefore, even when the non-reflecting part is an absorbing member, when the scale disk according to the present invention is applied, the position of the rotary shaft 2 can be visually confirmed, so that the relative position of the scale disk with respect to the rotary axis can be easily adjusted. Thus, the assembly accuracy can be improved and the assembly time can be shortened.

  Further, the drawing shows a schematic configuration of the scale disk 400 having a fastening structure with the rotary shaft 2 formed by resin molding. However, when the scale disk 400 is formed by resin molding, A structure that is fastened in such a manner that the rotary shaft 2 is inserted into the scale disk 400 can be easily created. When the rotating shaft 2 is assembled to the fastening portion 404 provided in the scale disk 400, there is a method in which the rotating shaft 2 is press-fitted and assembled in a state where there is no gap between the fastening portion 404 and the rotating shaft 2. . However, in the case of a high-precision optical encoder, it is necessary to assemble the scale disk 400 with high accuracy with respect to the rotation center 7 of the rotary shaft 2, so that there is a gap between the fastening portion 404 and the rotary shaft 2. A method is often used in which the scale disk 400 is fixed by means such as adhesion after being vacated and adjusted for eccentricity.

  At this time, a method of assembling using a UV light curable adhesive as an adhesive is effective. The UV light adhesive 403 is applied in advance to the inside of the rotating shaft 2 or the fastening portion 404, the rotating shaft 2 is inserted into the fastening portion 404, the eccentricity adjustment of the scale disk 400 with respect to the rotation center 7 is performed, and UV light is then applied. By irradiating and curing the adhesive 403, the scale disk 400 can be assembled with high positional accuracy.

  In the case of the above assembly, when a metal film is used for the reflection part 402 or when a conventional absorber is applied to the non-reflection part 401, the metal film or the absorption film hinders UV light irradiation. 5, even if the UV light is irradiated from above the scale disk 400, no light is irradiated on the adhesive 403, and a shadow is formed, so it is necessary to irradiate the UV light from the side of the scale disk 400. Thus, it takes time to cure, or a portion that is not irradiated, that is, an uncured portion is likely to be generated.

  On the other hand, by applying the reflecting member of the present invention, the reflecting member 402 and the absorbing member of the non-reflecting portion 401 made of a reflecting member have the property of transmitting light from visible light to ultraviolet light. When performing the attaching method, for example, even if UV light is irradiated from above the scale disk 400, the UV light is efficiently irradiated without being shielded by the reflective film or the absorbing film, and the efficiency is improved by shortening the curing time. In addition, it is possible to assemble with high reliability by reducing the uncured portion.

  In this embodiment, as an example, the infrared LED 1 is used as a light source, the reflection unit 402 has a high reflectance (or absorption coefficient) with respect to infrared light, and for light from ultraviolet light to visible light. Although a configuration using a reflective member or an absorbing member that transmits light is described, the configuration is not limited to this. If a reflecting member that reflects light rays in a wavelength region necessary for encoder signal detection and transmits a wavelength region necessary for visual observation including imaging by an image sensor or a wavelength region necessary for curing of the adhesive is used, The goal is achieved.

  The effectiveness of the present invention is not limited to the optical rotary encoder configured to irradiate the entire circumference of the scale disk 400 by arranging the light source 1 on the axis of the rotary shaft 2 as in the present embodiment. For example, it can be applied to a configuration in which infrared light from the light source 1 is irradiated to a part of the scale disk 400 as in Patent Document 3, and similarly applied to various optical rotary encoders that can achieve the above-described object. Is possible.

Embodiment 5 FIG.
FIG. 6 is a diagram showing a schematic structure of an optical encoder according to the fifth embodiment, and is a side view showing an outline of an optical linear encoder using a reflective linear scale and an index scale. The reflective linear scale 503 is a flat mirror that changes the direction of infrared rays, and the index scale 500 is an index slit plate.

  A light beam emitted from the infrared LED 1 that is a light source is applied to the index scale 500, and a light beam that has passed through the index scale 500 is applied to the reflective linear scale 503. The light beam reflected by the reflective linear scale 503 passes through the index scale 500 again and is detected by the light receiving element 5 provided on the light receiving unit 4. The index scale 500 includes a transmission part 501 that transmits light from the light source 1 and a non-transmission part 502 that blocks light by reflecting or absorbing the light. The reflective linear scale 503 that encodes the reflected light includes a reflective portion 504 that reflects light rays and a non-reflective portion 505 that transmits or absorbs light rays.

  The index scale 500 is formed by vapor-depositing a material such as a dielectric multilayer film on a plate-like substrate formed of optical resin molding or glass material. This non-transmissive portion 502 becomes a reflective member. The non-transmissive portion 502 has a high reflectance with respect to infrared light that is the wavelength of the light source LED 1, that is, blocks light without transmitting light in the infrared region, but reflects in the wavelength region of visible light or ultraviolet light. Since the rate is low and light rays from ultraviolet light to visible light are transmitted, for example, the infrared LED 1 and the light receiving element 5 of the light source are visually observed through the index scale 500 from the lower side of FIG. 6 (the side where the reflective linear scale 503 is present). The position of the reflection scale 503 can be visually observed through the scale 500 from the upper side (the side where the light source 1 and the light receiving element 5 are present) in FIG. The optical head 506 is configured to move in the directions of the left and right arrows in the figure.

  In particular, in a linear encoder that requires high accuracy, the relative positions of the light source 1, the index scale 500, the reflective linear scale 503, and the light receiving element 5 need to be assembled accurately. For this reason, the light source 1, the index scale 500, and the light receiving unit 4 are often assembled integrally as an optical head 506. At this time, when an index scale in which a conventional metal film is deposited on the non-transmissive portion is used, the position of the light source or the light receiving element cannot be visually confirmed from below the index scale. Position adjustment with a light source or a light receiving element becomes difficult. On the other hand, by using the index scale 500 according to the present embodiment, the position adjustment of the optical component in the optical head 506 can be easily and accurately performed. This is because the non-transmissive portion 502 is made of a reflective member that transmits visible light.

  Further, when assembling the index scale 500 to the optical head 506, a method of assembling using an UV light curable adhesive as an adhesive is effective. In the present embodiment, a UV photoadhesive is applied in advance to a bonding portion in the optical head 506 and the index scale 500 is arranged, and the index scale 500 is adjusted to be in an appropriate position with respect to the light source 1 and the light receiving element 5. Then, the index scale 500 can be assembled to the optical head 506 with high positional accuracy by irradiating UV light to cure the adhesive and assembling.

  When a metal film such as chromium is used for the non-transmissive portion 502 in the above assembly, the metal film hinders UV light irradiation, and a non-irradiated portion, that is, an uncured portion occurs, or the adhesive is cured. It will take time to do. On the other hand, by using the index scale 500 of the present embodiment, the non-transmissive portion 502 has a property of transmitting from visible light to ultraviolet light. Therefore, when performing the above assembly method, UV light is irradiated. Even if the non-transparent portion 502 is not shaded, it can be efficiently irradiated and can be highly efficient by shortening the curing time, and can be assembled with high reliability by reducing the uncured portion. .

  Further, the reflecting member used as the non-transmissive portion 502 in this embodiment does not necessarily have a high reflectance, and a member having a large absorption coefficient can be applied to the wavelength region necessary for encoder detection. . This can be freely designed by changing the material and film thickness of the dielectric multilayer film to be deposited, and has a high blocking property against the light from the light source 1 by having a high reflectance or a large absorption coefficient. become.

  As in the fourth embodiment, the reflective member of the present invention in which a dielectric multilayer film is deposited on the reflective portion 504 of the reflective linear scale 503 can also be used. In this case, when the reflective linear scale 503 is fixed to the guide using a UV light curable adhesive, assembling is improved in efficiency and reliability in the same manner as described above. be able to.

  In this embodiment, as an example, the infrared LED 1 is used as a light source, and the reflective portion 504 of the index scale 500 or the reflective linear scale 503 has a high reflectance (or absorption coefficient) for infrared light, and Although the configuration using the reflecting member (or absorbing member) that transmits visible light from ultraviolet light is described, the configuration is not limited to this. Reflective member (or absorbing member) that reflects or absorbs light in the wavelength region necessary for encoder signal detection and transmits the wavelength region necessary for visual observation including imaging by the image sensor or the wavelength region necessary for curing of the adhesive The object of the present invention can be achieved.

  The effectiveness of the present invention is not limited to the index scale configuration of the present embodiment, but can also be applied to a linear encoder using an optical rotary encoder or a transmission linear scale. The present invention can also be applied to various optical linear encoders that can achieve the above object.

Embodiment 6 FIG.
FIG. 7 is a diagram showing a schematic structure of an optical encoder according to the sixth embodiment. A light beam emitted from the infrared LED 1 serving as a light source is reflected by a prism 601 having a mirror surface 602 assembled to a motor contact surface 603, and the reflected light beam is applied to the scale disk 3. A slit 6 composed of a transmission part and a non-transmission part is provided on the scale disk 3, and a light beam transmitted through the scale disk 3 is encoded by the slit 6 and is provided on the light receiving part 4. 5 is detected. Therefore, the prism 601 converts the direction of infrared rays by combining a flat mirror.

  The prism 601 has a triangular prism base material formed by optical resin molding or glass cutting, and a material such as a dielectric multilayer film is deposited thereon, and has high reflectance with respect to infrared light, which is the wavelength of the light source. Since the reflectance in the wavelength region of visible light and ultraviolet light is low and light rays from ultraviolet light to visible light are transmitted, the motor contact surface 603 can be visually observed from above the prism 601 (the side where the light source 1 is present). . The upper surface of the motor contact surface 603 is marked for alignment. When the prism 601 is assembled, the alignment mark on the upper surface of the motor contact surface 603 is observed through the prism 601 and adjusted so as to face the light source. . Similarly to the first to fifth embodiments, UV light can be efficiently irradiated without making a shadow on the mirror surface 602 when an assembly is performed using an adhesive that is cured by irradiation with UV light. It is.

  In general, a mirror made of an optical prism using glass or optical resin reflects light rays under a total reflection condition due to a difference in refractive index. Because it is made of transparent material, it can be assembled visually or with UV light adhesive, but it does not reflect light rays with angles other than the total reflection conditions, so it reflects light at any angle. I can't let you. In FIG. 7, since the light beam is incident at an incident angle of 45 degrees, the same effect can be obtained even when a general optical prism is used. However, when reflection at a deep angle is necessary due to the necessity of the optical system, In some cases, the reflective member of the present invention is particularly effective. That is, by using the mirror of the present invention for the prism 601, it is possible to reflect light rays at angles other than the total reflection condition while maintaining the ease of visual assembly and the use of a UV light adhesive.

  In addition, the effectiveness of the present invention is not limited to the configuration of the present embodiment, in an optical encoder using a prism-like reflecting member that combines a flat mirror or a flat mirror for converting the direction of the light beam, This is effective over all optical encoders that require adjustment of the position of the reflecting member or members around the reflecting member.

  As described above, in common with all the embodiments, the optical encoder according to the present invention reflects a light source emitting a light beam and a light beam in a wavelength region necessary for signal detection, and a wavelength region necessary for signal detection. Since the reflection member that transmits all or part of the light beams in the other wavelength regions and the light receiving element that receives the light beams are provided, the assembly of the optical encoder can be easily performed with high accuracy.

  The optical encoder according to the present invention includes a light source that emits a light beam, a reflective member that reflects when the light beam is infrared light, and a transparent member that transmits when the light beam is visible light and ultraviolet light, and a light beam. Since the light receiving element for receiving light is provided, the optical encoder can be easily assembled with high accuracy.

  Furthermore, since the reflecting member transmits ultraviolet light, it is possible to perform assembly using an adhesive that cures when irradiated with ultraviolet light, and the optical encoder is easily assembled with high accuracy. be able to.

1 is a diagram showing a schematic structure of an optical encoder according to Embodiment 1. FIG. 6 is a diagram illustrating a schematic structure of an optical encoder according to a second embodiment. FIG. 6 is a diagram illustrating a schematic structure of an optical encoder according to a second embodiment. FIG. 6 is a diagram illustrating a schematic structure of an optical encoder according to a third embodiment. FIG. FIG. 10 is a diagram illustrating a schematic structure of an optical encoder according to a fourth embodiment. FIG. 10 is a diagram illustrating a schematic structure of an optical encoder according to a fifth embodiment. FIG. 10 is a diagram showing a schematic structure of an optical encoder according to a sixth embodiment.

Explanation of symbols

1 LED (light source), 2 rotation axis, 3 scale disk, 4 light receiving part, 5 light receiving element, 6 slit, 7 rotation center,
DESCRIPTION OF SYMBOLS 101 Concave mirror, 102 Reflective film, 103 Mirror receiver, 104 rays, 105 rays, 106 Adhesive, 107 Above concave mirror, 201 Transmission part, 202 Non-transmission part, 203 Adhesive, 204 Fastening part, 300 Linear scale, 301 Transmission part, 302 Non-transmission part, 400 Scale disk, 401 Non-reflection part, 402 Reflection part, 403 Adhesive, 404 Fastening part, 500 Index scale, 501 Transmission part, 502 Non-transmission part, 503 Reflective linear scale, 504 Reflection part, 505 non-reflection part, 506 head, 601 prism, 602 mirror surface, 603 motor contact surface.

Claims (6)

A light source that emits infrared rays;
A reflective member that reflects infrared light from the light source and transmits at least one of visible light and ultraviolet light; and
A transmission type code plate irradiated with infrared rays reflected by the reflection member;
An optical encoder comprising: a light receiving element that receives infrared light transmitted through the transmission code plate. 2. The optical encoder according to claim 1, wherein the reflecting member is used in a lens having a function of converging, diverging, or collimating the infrared ray. The optical encoder according to claim 1, wherein the reflecting member is used as a flat mirror that changes a direction of the infrared ray. The optical encoder according to claim 1, wherein the reflecting member is used in a prism that converts a direction of the infrared ray by combining a flat mirror. A light source that emits infrared rays;
A reflective code plate having a reflecting member that reflects infrared light from the light source and transmits at least one of visible light and ultraviolet light;
An optical encoder comprising: a light receiving element that receives infrared light reflected by the reflective code plate. 6. The optical encoder according to claim 1, wherein the reflecting member has a dielectric multilayer film.

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