EP-4737862-A1 - ENCODER

Abstract

Encoder (10) that is an optical battery-less encoder detects rotation of shaft (80) about rotation axis (A). Encoder (10) includes fixing screw (30) that is screwed into screw hole (82) in an end surface of shaft (80), magnet (40) arranged on fixing screw (30), and magnetic sensor (64) that generates power using a magnetic field generated by magnet (40). Fixing screw (30) includes screw part (32) screwed into screw hole (82) and head part (31) connected to screw part (32) and including arrangement part (34) to which arranging magnet (40) is arranged.

Inventors

• YAMAGUCHI HIDEO
• ISE Minori

Assignees

• Panasonic Intellectual Property Management Co., Ltd.

Dates

Publication Date

20260506

Application Date

20240411

Claims (10)

1. An encoder that is an optical battery-less encoder detects rotation of a shaft about a rotation axis, the encoder comprising: a light source that emits light; a rotation plate that rotates together with the shaft and modulates the light to generate modulated light; a light receiving element that receives the modulated light; a fixing screw screwed into a screw hole in an end surface of the shaft; a support member that is fixed to the shaft by the fixing screw and supports the rotation plate; a magnet arranged on the fixing screw; and a magnetic sensor that generates power using a magnetic field generated by the magnet, wherein the fixing screw includes: a screw part screwed into the screw hole, and a head part connected to the screw part and including an arrangement part to which the magnet is arranged.
2. The encoder according to Claim 1, wherein the arrangement part is a recess recessed in a direction along the rotation axis, and at least one end of the recess extends to an end of the head part when viewed from a direction along the rotation axis.
3. The encoder according to Claim 1 or 2, wherein when viewed from a direction along the rotation axis, the head part has end edges having two sides parallel to each other.
4. The encoder according to Claim 3, wherein when viewed from a direction along the rotation axis, the magnet has a rectangular shape having two short sides and two long sides, and the two short sides face the two sides of the head part, respectively.
5. The encoder according to Claim 4, wherein the two long sides have a length of equal to or less than a distance between the two sides.
6. The encoder according to Claim 1 or 2, wherein the head part has a shape of a polygon when viewed from a direction along the rotation axis.
7. The encoder according to Claim 6, wherein the head part has a shape of a regular hexagon when viewed from a direction along the rotation axis.
8. The encoder according to Claim 1 or 2, wherein the magnet is arranged inside an outer edge of the head part when viewed from a direction along the rotation axis.
9. The encoder according to Claim 1 or 2, wherein the magnetic sensor is arranged on the rotation axis.
10. The encoder according to Claim 1 or 2, wherein the magnetic sensor includes a magnetic member that produces a large Barkhausen effect by a change in an external magnetic field.

Description

TECHNICAL FIELD The present disclosure relates to an encoder. BACKGROUND ART Conventionally, an optical battery-less encoder using an annular magnet that rotates about a rotation axis, a power generation element including a magnetic wire and a coil, and a light source and a light receiving element is known (see, for example, PTL 1). In the optical battery-less encoder described in PTL 1, power is generated in a power generation element such as a Wiegand wire sensor using a magnetic field generated by a rotating magnet. Citation List Patent Literature PTL 1: US Patent No. 9528856 SUMMARY OF THE INVENTION However, in an optical battery-less encoder, more efficient use of a magnetic field generated by a magnet is required. An object of the present disclosure is to provide an optical battery-less encoder that can efficiently use a magnetic field generated by a magnet. An encoder according to one aspect of the present disclosure that is an optical battery-less encoder detects rotation of a shaft about a rotation axis. The encoder according to one aspect of the present disclosure includes a light source that emits light, a rotation plate that rotates together with the shaft and modulates the light to generate modulated light, and a light receiving element that receives the modulated light. Further, the encoder according to one aspect of the present disclosure includes a fixing screw screwed into a screw hole in an end surface of the shaft, a support member that is fixed to the shaft by the fixing screw and supports the rotation plate, a magnet arranged on the fixing screw, and a magnetic sensor that generates power using a magnetic field generated by the magnet. The fixing screw includes a screw part screwed into the screw hole, and a head part connected to the screw part and including an arrangement part to which the magnet is arranged. The present disclosure can provide an optical battery-less encoder that can efficiently use a magnetic field generated by a magnet. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view illustrating an overall configuration of an encoder according to a first exemplary embodiment.Fig. 2 is an exploded perspective view illustrating an overall configuration of the encoder according to the first exemplary embodiment.Fig. 3 is a plan view illustrating configurations of a magnet and a fixing screw according to the first exemplary embodiment.Fig. 4 is a schematic diagram illustrating an example of a configuration of a magnetic sensor according to the first exemplary embodiment.Fig. 5 is a perspective view illustrating configurations of a fixing screw and a magnet according to a second exemplary embodiment.Fig. 6 is a plan view illustrating a configuration of a fixing screw according to the second exemplary embodiment.Fig. 7 is a cross-sectional view illustrating a configuration of a fixing screw according to the second exemplary embodiment.Fig. 8 is a plan view illustrating a configuration of a magnet according to a first modification of the second exemplary embodiment.Fig. 9 is a plan view illustrating a configuration of a fixing screw according to a second modification of the second exemplary embodiment.Fig. 10 is a cross-sectional view illustrating a configuration of a fixing screw according to the second modification of the second exemplary embodiment. DESCRIPTION OF EMBODIMENTS Hereinafter, exemplary embodiments of the present disclosure will be described. The exemplary embodiments to be described below each illustrate one specific example of the present disclosure. Thus, numerical values, constituent elements, arrangement positions and connection modes of the constituent elements, steps order of the steps, and the like illustrated in the following exemplary embodiments are merely examples, and are not intended to limit the present disclosure. Thus, among the constituent elements in the following exemplary embodiments, constituent elements that are not described in independent claims indicating the highest concept of the present disclosure are described as optional constituent elements. In addition, each of the drawings is a schematic diagram, and is not necessarily strictly illustrated. Note that, in each of the drawings, substantially the same configurations are denoted by the same reference marks to eliminate or simplify duplicated description. In addition, in the present specification, terms indicating the relationship between elements such as vertical and parallel, and terms indicating the shape of elements such as polygon, regular hexagon, annular shape, rectangular shape, columnar shape, and disk shape are not expressions indicating only strict meanings, but are expressions meaning to include a substantially equivalent range, for example, a difference of about several%. (First exemplary embodiment) Encoder 10 according to the first exemplary embodiment will be described. [1-1. Overall configuration] An overall configuration of encoder 10 according to the present