JP2005233870A - Optical rotation sensor with original position detecting function and bearing with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical rotation sensor with an origin position detecting function of a compact constitution provided with an origin position detecting function in addition to a rotational speed detecting function and provide a bearing provided with the same. <P>SOLUTION: In the optical rotation sensor A, a cord wheel 2 is provided with a plurality of grids 3 for rotation detection aligned in a circumferential direction, and an origin position indicating part 4 at one location in the circumferential direction in the same circumferential direction. Further, the optical rotation sensor A is constituted of light sources 5 and 6 for rotation detection; a light source 7 for origin position detection; and light receiving bodies 5a, 6a, and 7a opposed to them. The light sources 5 and 6 for rotation detection and the light source 7 for origin position detection emit light of wavelengths different from each other. For example, the light sources 5 and 6 for rotation detection emit infrared light, and the light source 7 for origin position detection emits ultraviolet light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical rotation sensor with an origin detection function capable of obtaining not only a pulse signal for rotation speed detection but also an origin signal, and a bearing provided with the rotation sensor.

The rotation sensor is roughly classified into an incremental type and an absolute type. However, a general incremental type rotation sensor requires an initialization process, and an absolute type rotation sensor has a complicated structure and is expensive. Therefore, an incremental rotation sensor that can obtain an origin signal has been proposed.
For example, as an incremental type rotation sensor with an origin detection function, there is a magnetic type disclosed in Patent Document 1. This is an encoder in which a rotation detection grid array magnetized and an origin display section at one circumferential direction are arranged in the axial direction on the outer peripheral surface of a cylindrical wheel. In the optical type, there is an encoder in which a rotation-detecting grid array and one origin display portion in the circumferential direction are arranged in a radial direction on a disk-shaped wheel.

Conventionally, as shown in Patent Document 1, a bearing with a rotation sensor in which a rotation sensor is provided in a rolling bearing has been proposed. If the bearing is provided with a rotation sensor in this way, it is not necessary to separately attach a rotation sensor, and the assembly of the bearing-using device can be simplified and space saving can be achieved.
JP 2003-269475 A

A conventional rotation sensor with an origin detection function, in which a rotation detection grid array and an origin display unit are arranged side by side in the axial direction as shown in Patent Document 1, has a problem that the encoder is elongated in the axial direction. . In addition, the magnetic type has a problem of low resolution. Further, in the optical rotation sensor with the origin detection function, the rotation detection grid array and the origin display unit arranged in the radial direction have a problem that the encoder becomes larger in the radial direction.
For this reason, when a bearing is provided with a rotation sensor, there is a problem that the sensor portion of the bearing with a rotation sensor becomes large.

An object of the present invention is to provide an optical rotation sensor with an origin detection function that can have a compact configuration while having an origin detection function in addition to a rotation speed detection function.
Another object of the present invention is that the advantages of the optical rotation sensor with an origin detection function of the present invention are effectively exhibited, the rotation sensor portion can be made compact, and both the rotation speed detection function and the origin detection function are provided. It is to provide a bearing with a rotation sensor.

An optical rotation sensor with an origin detection function of the present invention includes a plurality of grids for rotation detection arranged in the circumferential direction, a code wheel having one origin display section in the circumferential direction, the grid of the code wheel, A light source for rotation detection and a light source for origin detection that respectively irradiates detection light to the origin display unit, and a rotation for detecting reflected light or transmitted light of the grid or inter-grating part of the code wheel and the origin display unit, respectively An optical rotation sensor having a light receiving body for detection and a light receiving body for origin detection, wherein the light source for rotation detection and the light source for origin detection emit light of mutually different wavelengths. Features.
The plurality of rotation detection gratings and the origin display unit may be positioned on the same circumference of the code wheel.

  According to this configuration, the light source for rotation detection and the light source for origin detection that irradiate detection light to the grating and the origin display unit in the code wheel emit light of different wavelengths, respectively. Even if the display units are on the same circumference or close to each other, the rotation detection light and the origin detection light can be distinguished and detected without interference. Therefore, the code wheel can be made compact while having both the row of the lattice for rotation detection and the origin display section. In particular, when the rotation detection grid and the origin display section are arranged on the same circumference, the code wheel can be of the same size as that of a simple incremental type. Therefore, it is possible to realize a rotation sensor having a compact configuration while having both functions of rotation detection and origin detection. Further, since the optical type is adopted, the resolution is higher than that of the magnetic type, and the rotation detection accuracy is high.

In the optical rotation sensor with an origin detection function of the present invention, the rotation detection light source and the light receiving body emit and receive infrared light, respectively, and the origin detection light source and the light receiving body respectively receive ultraviolet light. It may be one that emits light and receives visible light. The origin display part is a fluorescent part.
In this configuration, rotation detection is performed using infrared light, and origin detection is performed using visible light reflected by the fluorescent portion, so that reliable interference between rotation detection and origin detection can be avoided. Since the origin display section is a fluorescent section, reflected light can be obtained separately from the grid and the origin display section even if it is provided on the code wheel so as to overlap the rotation detection grid. There is no adverse effect of disposing the display unit on the same circumference.

In the optical rotation sensor with an origin detection function of the present invention, a hydrophilic coating may be applied to the surface of the code wheel provided with the lattice. This hydrophilic coating may be a photocatalytic superhydrophilic coating.
If the hydrophilic coating is applied, the hydrophilicity of the surface provided with the lattice is maintained, the occurrence of fogging on the surface of the code wheel is prevented, and high-precision rotation detection is maintained. In particular, when a photocatalytic superhydrophilic coating is used, when a light source for detecting ultraviolet light is used as the light source for detecting the origin, the superhydrophilicity is always maintained by the photocatalytic action based on the irradiation of the ultraviolet light. It is. Accordingly, the effect of preventing the occurrence of fogging becomes more prominent.

  Another optical rotation sensor with an origin detection function according to the present invention includes a transmission type grating for rotation detection arranged in the circumferential direction, a code wheel having a reflection type origin display portion in one circumferential direction, A rotation detection light source and an origin detection light source that are provided apart from each other in the circumferential direction of the code wheel and irradiate detection light to the lattice and the origin display unit, respectively, and transmission through the lattice or interstitial part of the code wheel A rotation detection light-receiving body and an origin detection light-receiving body that respectively detect light and reflected light of the origin display section.

In this way, even if the rotation detection grid is a transmission type and the origin display unit is a reflection type, even if there is a rotation detection grid and an origin display unit on the same circumference, the rotation detection light source and If the light source for origin detection is arranged apart in the circumferential direction, the light for rotation detection and the light for origin detection can be distinguished and detected without interference. Therefore, even in this configuration, a compact configuration can be achieved while providing an origin detection function in addition to the rotation speed detection function.
In the case of this configuration, it is more preferable for both light sources to emit light having different wavelengths, so that interference can be reliably avoided. Can be detected.

A bearing with a rotation sensor according to the present invention includes a bearing having a rotating wheel and a fixed ring that are rotatable with respect to each other, and an optical rotation sensor with an origin detection function according to any one of the above-described configurations of the present invention. A wheel is attached, and the light sources and photoreceptors are attached to a fixed wheel.
According to the bearing with the rotation sensor of this configuration, since the rotation sensor is attached to the bearing, it is not necessary to attach the rotation sensor separately, and the assembly to the bearing using device is simplified. Further, the advantage of having a rotational speed detection function and an origin detection function with a compact configuration in the optical rotation sensor with an origin detection function according to the present invention is effectively exhibited, and the rotation sensor portion can be configured compactly, and the rotational speed Both the detection function and the origin detection function can be provided.

In the bearing with a rotation sensor according to the present invention, when the bearing is a rolling bearing, a seal that seals an annular space between the rotating wheel and the fixed wheel is attached to the rotating wheel, and the seal may be used as the code wheel. In this case, both the grating and the origin display unit are of a reflection type, and the rotation detection light receiver and the origin detection light receiver receive reflected light.
As described above, when the seal is also used as the code wheel, the bearing with the rotation sensor can be configured without increasing the number of parts, and the entire configuration of the bearing with the rotation sensor can be made more compact.

An optical rotation sensor with an origin detection function according to the present invention emits light having different wavelengths from a light source for rotation detection and a light source for origin detection that respectively irradiates detection light to a lattice and an origin display section in a code wheel. As a result, it is possible to provide a rotation sensor with a compact configuration while having an origin detection function in addition to a rotation speed detection function. Moreover, since it is optical, rotation detection with high resolution becomes possible.
Since the optical rotation sensor with other origin detection function of the present invention is a transmission type for rotation detection and a reflection type for origin detection, even in this configuration, while having an origin detection function in addition to the rotation speed detection function, It can be a compact rotation sensor. Moreover, since it is optical, rotation detection with high resolution becomes possible.

  Since the bearing with a rotation sensor of the present invention includes the optical rotation sensor with an origin detection function of the present invention, the rotation sensor portion can be configured compactly and has both a rotation speed detection function and an origin detection function. And can.

  A first embodiment of the present invention will be described with reference to FIG. The rotation sensor A has a function of detecting the rotation speed and direction and a function of detecting the origin, and includes a non-transparent disk-shaped code wheel 2. The code wheel 2 is fixed to the tip of the rotating shaft 1. On the outer periphery of the code wheel 2, a large number of grids 3 for rotation detection are formed in a line at equal intervals along the same circumference. These gratings 3 are formed of slits for transmitting light. An origin display section 4 is provided at one place on the same circumference as the arrangement of the grids 3 of the code wheel 2. The origin display part 4 is provided in the part 3a between the lattices on the circumference, that is, a part between adjacent lattices 3. The origin display unit 4 is composed of a fluorescent unit to which a phosphor that emits visible light by irradiation with ultraviolet light is attached.

On one side of the code wheel 2, two rotation detection light sources 5 and 6 are arranged at a predetermined interval in the circumferential direction so as to face the radial position where the grating 3 is formed. ing. The predetermined interval is preferably a position shifted from the multiple of the arrangement pitch of the grating 3 by a predetermined phase angle, for example, 1/4 of the arrangement pitch. These rotation detection light sources 5 and 6 are each composed of an infrared light emitter such as an infrared light emitting diode. On the opposite side of the light sources 5 and 6 with the code wheel 2 sandwiched therebetween, rotation detection light receiving bodies 5a and 6a for selectively receiving only infrared light are disposed.
Further, a light source 7 for detecting the origin is disposed on the one side of the code wheel 2 so as to face the radial position where the origin display unit 4 is formed, and in the vicinity thereof, the origin display unit of the light of the light source 7 is disposed. A light-receiving body 7a for detecting the origin that receives the reflected light from 4 is disposed. The light source 7 for detecting the origin is composed of an ultraviolet light emitter such as an ultraviolet light emitting diode, and a light receiver 7a that selectively receives only visible light is used.

  A hydrophilic coating (not shown) is applied to the surface of the code wheel 2 on which the origin display portion 4 is formed. This hydrophilic coating is preferably, for example, a photocatalytic superhydrophilic coating that generates a photocatalytic action based on ultraviolet irradiation. The hydrophilic coating is preferably applied over the entire surface of the code wheel 2 on which the origin display portion 4 is formed or the entire circumference of the radial portion provided with the origin display portion 4. 4 and its periphery may be applied.

In the rotation sensor A having the above configuration, when the code wheel 2 rotates, the origin display unit 4 passes through the irradiation region of the light source 7 for origin detection. At this time, the ultraviolet light emitted from the light source 7 is reflected as visible light by the origin display unit 4 made of a fluorescent part, and the reflected light is received by the visible light receiver 7a to output an origin signal.
As the code wheel 2 rotates, the infrared light emitted from the rotation detection light sources 5 and 6 passes through the grating 3, and the transmitted light is received by the light receivers 5a and 6a. This light reception is made regularly according to the formation pattern of the grating 3, and an incremental rotation pulse signal corresponding to the rotation speed of the code wheel 2 is output from each of the light receivers 5 a and 6 a. With this pulse signal, the rotational speed of the code wheel 2 can be obtained.
If the phases of the pulse patterns of the two photoreceptors 5a and 6a are shifted from each other by 90 °, for example, the rotation direction of the code wheel 2 can be determined by determining which of the two pulses is ahead with a simple circuit. Can be determined.

  In this case, since the detection of the rotation speed and direction and the origin detection are performed by light having different wavelengths, the rotation detection grating 3 and the origin display unit 4 of the code wheel 2 and the light source opposed to them. Even if 5, 6, 7 and the photoreceptors 5a, 6a, 7a are on the same circumference, their detection lights do not interfere with each other, and individual detection signals are accurately distinguished and output. In particular, the rotation detection light sources 5 and 6 emit infrared light, and the origin detection light source 7 emits ultraviolet light. The light receiving bodies 5a, 6a and 7a selectively receive infrared light and visible light. Therefore, the interference of detection light can be avoided more reliably. Therefore, while having both the rotation detection function and the origin detection function, it is not necessary to increase the diameter of the code wheel 2, and the rotation sensor can be made compact.

  Further, since the hydrophilic coating is applied to the surface of the code wheel 2 on which the origin display section 4 is applied, the hydrophilicity of the surface of the code wheel 2 is maintained and the occurrence of fogging is prevented. Therefore, accurate origin detection or rotation speed / rotation direction detection can be performed without causing detection failure due to fogging. When this hydrophilic coating is a photocatalytic superhydrophilic coating, the superhydrophilicity is always maintained by the photocatalytic action based on the irradiation of ultraviolet rays emitted from the light source 7 for detecting the origin, and it is effective for preventing the occurrence of fogging. Such a hydrophilic coating is preferably applied not only to the surface of the code wheel 2, but also to the light emitting surfaces of the light sources 5, 6, and 7 and the light receiving surfaces of the photoreceptors 5a, 6a, and 7a. The effect of preventing detection failure can be obtained more reliably. Moreover, even if it replaces with hydrophilic coating and water-repellent coating is given, the fog prevention effect is acquired.

  In the above embodiment, the rotation detection light sources 5 and 6 and the origin detection light source 7 emit light having different wavelengths. However, as in this embodiment, the rotation detection grating 3 is used. If the origin detection unit 4 is a reflection type, the light sources 5 and 6 for rotation detection and the light source 7 for origin detection may emit light having the same wavelength. Even in this case, the detection can be performed separately without causing the problem of interference between the rotation detection light and the origin detection light. If the rotation direction light source and the photoreceptor are not required to detect the rotation direction, one light source and one light receiver may be used.

  Moreover, although the said embodiment described the example in which the code wheel 2 consists of a non-translucent disc, you may use a translucent disc. In that case, a large number of non-translucent materials such as paints and thin films are formed on the surface of the translucent disc in the circumferential direction with a small gap instead of the lattice 3 made of the slits. A lattice similar to the above can be formed by a formation pattern in which a portion and a non-light-transmitting portion are repeated.

  FIG. 2 shows another embodiment of the present invention. The rotation sensor B of this embodiment is an example in which the rotation detection grating 3 is of a reflective type in the first embodiment. In this example, the grating 3 is a non-reflecting part and the inter-grating part 3a is a reflecting part. Accordingly, the respective light receiving bodies 5a and 6a for detecting rotation are arranged in the vicinity of the light sources 5 and 6 so as to receive the reflected light from the grating 3 of the light emitted from the respective light sources 5 and 6. . Similarly to the first embodiment, the origin display unit 4 is made of a fluorescent part, but in this embodiment, a fluorescent part to be the origin display part 4 is provided on the surface of the grating 3 which is a non-reflective part. Other configurations are the same as those of the first embodiment.

In the case of this embodiment as well, the same circumference of the code wheel 2 is used because different wavelengths of light such as infrared rays and ultraviolet rays are used for rotation detection and origin detection as in the first embodiment. Even if the rotation detection grid 3 and the origin display unit 4 are on the top, the rotation detection and the origin detection can be performed separately without interference problems. Also in this embodiment, since the two light sources 5 and 6 and the photoreceptors 5a and 6a are provided for rotation detection, the rotation direction can be detected.
Also in this embodiment, since the hydrophilic surface such as the photocatalytic superhydrophilic coating is applied to the surface of the code wheel 2 on which the lattice 3 is formed, the hydrophilicity of the surface of the code wheel 2 is maintained and the occurrence of fogging is prevented. Is done. In particular, in the case of this embodiment, since it is a reflection type, if the code wheel 2 is fogged, a malfunction of rotation detection is likely to occur. However, such a malfunction is prevented by the hydrophilic coating.

  In each of the above embodiments, infrared light and ultraviolet light are used. However, the present invention is not limited to this, and light of other wavelengths may be used. That is, the rotation detection light sources 5 and 6 and the origin are within a range in which the light detection bodies 5a and 6a for rotation detection and the light reception body 7a for origin detection can selectively receive light depending on the difference in wavelength. A light source that emits light having a wavelength different from that of infrared light or ultraviolet light may be used as the light source 7 for detection. In contrast to the above, ultraviolet light may be used for rotation detection and infrared light for origin detection may be used. In each of the above embodiments, the code wheel 2 is a disk, but the code wheel 2 may be cylindrical.

  3 to 4 show an embodiment of a bearing with a rotation sensor. In this embodiment, a rotation sensor 14 is attached to one end of the bearing 8. The bearing 8 is a rolling bearing in which a plurality of rolling elements 9 made of balls are interposed between raceway surfaces 10 a and 11 a of the inner ring 10 and the outer ring 11. Each rolling element 9 is held by a cage 12. The inner ring 10 is a rotating wheel and the outer ring 11 is a fixed ring. One end of the annular space between the inner ring 10 and the outer ring 11 is sealed with the rotation sensor 14, and the other end is sealed with a seal member 13. The seal member 13 is a contact seal attached to the outer ring 11, and the seal lip 13 a is in sliding contact with the outer diameter surface of the inner ring 10.

  The rotation sensor 14 has the same basic configuration as the rotation sensor B according to the embodiment of FIG. 2 and is configured as follows. On the outer diameter surface of the inner ring 10, a non-translucent annular code wheel 2 is fixed in a fitted state via a cylindrical portion 2a. As shown in FIG. 6, a large number of gratings 3 are provided on the surface of the code wheel 2 along the circumferential direction. The lattice 3 becomes a non-reflective portion, and the inter-lattice portion 3a becomes a reflective portion. An origin display section 4 is provided at one place on the circumference where the lattice 3 of the code wheel 2 is formed. The origin display portion 4 is a fluorescent portion coated with a phosphor, and the phosphor is applied to one lattice 3. A hydrophilic coating such as a photocatalytic superhydrophilic coating is applied to the surface of the code wheel 2 on which the lattice 3 and the origin display portion 4 are provided.

  As shown in an enlarged view in FIG. 5, a support cylinder 15 constituting a part of the fixture 15 </ b> A is attached to the inner diameter surface of the outer ring 11 in a fitted state. The support cylinder 15 is a member for attaching the light source 5 and the like, and is also used as a labyrinth seal forming member together with the code wheel 2. That is, the outer peripheral edge portion of the code wheel 2 attached to the inner ring 10 faces the supporting cylinder 15 in the proximity state with the labyrinth gap r. As a result, the annular space is sealed while allowing the inner and outer rings 10, 11 to rotate relative to each other. The supporting cylinder 15 includes a small-diameter cylindrical portion 15a that is integrally fitted to the inner diameter surface of the outer ring 11, and a large-diameter cylindrical portion 15b that is continuous with the small-diameter cylindrical portion 15a. A light-emitting body having a U-shaped cross-section and a light-receiving body support ring 16 are integrally fitted in the inner cylinder portion of the large-diameter cylindrical portion 15b. The support ring 16 and the support cylinder 15 constitute a fixture 15A.

  Two light sources 5 and 6 for rotation detection (FIG. 3), a light source 7 for origin detection, and each of these, so that the inner surface of the support ring 16 faces the formation portion of the lattice 3 of the code wheel 2 Photodetectors 5a and 6a for rotation detection corresponding to the light sources 5, 6 and 7 and a photoconductor 7a for origin detection are attached via a substrate 17 (FIG. 5). For example, as shown in FIG. 3, the light sources 5, 6, and 7 are arranged at an interval of approximately 90 ° in the circumferential direction.

  According to the bearing with the rotation sensor of this configuration, when the inner ring 10 rotates, the rotation sensor 14 detects the rotation. Similar to the embodiment shown in FIG. 2, the rotation sensor 14 detects the rotation speed and direction and detects the origin by using light having different wavelengths, so that the rotation detection grating of the code wheel 2 is detected. 3 and the origin display section 4, and the light sources 5, 6, and 7 and the light receivers 5a, 6a, and 7a that are opposed to them are on the same circumference, the detection lights do not interfere with each other. The detection signals are output with proper discrimination. Further, the hydrophilic coating applied to the code wheel 2 prevents fogging and enables stable detection.

  FIG. 7 shows another embodiment of the bearing with a rotation sensor according to the present invention. In this bearing with a rotation sensor, a seal 13A is attached to the inner ring 10, and this seal 13A is a code wheel. The seal 13 </ b> A is a contact seal in which an elastic body such as rubber is provided on a core metal, and is attached to the inner ring 10 and is in sliding contact with the inner diameter surface of the outer ring 11. Similar to the code wheel 2 in the embodiment shown in FIGS. 4 to 6, the rotation detection grid 3 and the origin display section 4 (none of which are shown in FIG. 7) are provided on the bearing outward surface of the seal 13 </ b> A. Has been given. Further, with respect to the lattice 3 and the origin display section 4 of the seal 13A serving as the code wheel, as in the embodiment shown in FIGS. 4 to 6, the rotation detection light sources 5 and 6 and the origin detection light source 7 are used. , And light receiving portions 5a, 6a, 7a corresponding thereto. These light sources 5, 6, and 7 and the light receiving portions 5a, 6a, and 7a are attached to the outer ring 11 via a ring-shaped fixture 15B.

  In the case of this embodiment, since the seal 13A is also used as a code wheel, a bearing with a rotation sensor can be configured without increasing the number of components, and the entire configuration of the bearing with a rotation sensor can be made even more compact. Other configurations and effects in this embodiment are the same as those in the embodiment shown in FIGS.

In the bearing with a rotation sensor of each of the above embodiments, the inner ring 10 is a rotating ring and the outer ring 11 is a fixed ring, but both may be reversed. In that case, the light sources 5, 6 and 7 and the photoreceptors 5 a, 6 a and 7 a are attached to the inner ring 10, and the code wheel 2 is attached to the outer ring 11. The rotation sensor 14 has basically the same configuration as the rotation sensor B of the embodiment of FIG. 2, but is not limited to this, and the rotation sensor A of the embodiment of FIG. 1 may be used.
In this embodiment, the bearing 8 is a single-row rolling bearing. However, the bearing 8 may be a roller bearing or a double-row bearing. For example, the bearing 8 may be a wheel bearing such as an automobile hub unit bearing. Furthermore, the bearing 8 may be a sliding bearing.

It is a perspective view of an optical rotation sensor with an origin detection function concerning a 1st embodiment of this invention. It is a perspective view of the optical rotation sensor with an origin detection function concerning other embodiments of this invention. It is a typical perspective view which shows the same another Example. It is a front view which shows embodiment of a rolling bearing with the rotation sensor in this invention. It is the XX sectional view taken on the line of FIG. It is an enlarged view of the Y section of FIG. It is a partial arrow line view in the ZZ line of FIG. It is a fragmentary sectional view which shows other embodiment of a bearing with a rotation sensor.

Explanation of symbols

2 ... code wheel 3 ... lattice 3a ... interstitial portion 4 ... origin display units 5, 6 ... light source 5a, 6a for rotation detection ... light receiver 7 for rotation detection ... light source 7a for origin detection ... light reception for origin detection Body 8 ... Bearing 10 ... Inner ring (rotating ring)
11 ... Outer ring (fixed ring)
13A: Seals A, B, 14 ... rotation sensors that are code wheels

Claims (8)

  A plurality of rotation detection gratings arranged in the circumferential direction, a code wheel having one origin display section in the circumferential direction, and a rotation detection section that irradiates the grating and origin display section of the code wheel with detection light, respectively. A light source for detecting the origin and a light source for detecting the origin, a light receiving body for detecting the rotation and a light receiving body for detecting the origin of the reflected light or transmitted light of the grating or the inter-grating part of the code wheel and the origin display part, respectively An optical rotation sensor with an origin detection function, wherein the rotation detection light source and the origin detection light source emit light having different wavelengths.   The optical rotation sensor with an origin detection function according to claim 1, wherein the plurality of rotation detection gratings and the origin display unit are positioned on the same circumference of the code wheel.   3. The light source and light receiving body for detecting rotation according to claim 1 or 2, respectively, emitting and receiving infrared light, and the light source and light receiving body for detecting origin respectively emit ultraviolet light and visible light. An optical rotation sensor with an origin detection function in which the origin display part is a fluorescent part.   4. The optical rotation sensor with an origin detection function according to claim 1, wherein a hydrophilic coating is applied to a surface of the code wheel provided with the origin display portion or the lattice. 5.   5. The optical rotation sensor with an origin detection function according to claim 4, wherein the hydrophilic coating is a photocatalytic superhydrophilic coating.   A transmission type grating for detecting rotation arranged in the circumferential direction, a code wheel having a reflection type origin display portion at one circumferential direction, and the gratings provided apart from each other in the circumferential direction of the code wheel. And a rotation detection light source for irradiating detection light to the origin display unit, a light source for origin detection, and a rotation for detecting the transmitted light of the code wheel or the inter-grating part of the code wheel and the reflected light of the origin display unit, respectively. An optical rotation sensor with an origin detection function, having a photoreceptor for detection and a photoreceptor for origin detection.   A bearing having a rotating wheel and a fixed ring that are rotatable with respect to each other, and an optical rotation sensor with an origin detection function according to any one of claims 1 to 5, wherein the code wheel is attached to the rotating wheel. A bearing with a rotation sensor in which the light sources and the photoreceptors are attached to a fixed ring.   8. The bearing according to claim 7, wherein the bearing is a rolling bearing, a seal that seals an annular space between the rotating wheel and the fixed wheel is attached to the rotating wheel, the seal is used as the code wheel, and both the lattice and the origin display section are provided. Reflective bearing with rotation sensor.

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