Encoder and light receiving device for encoder
AssigneeHamamatsu Photonics K.K.
InventorsSeiichiro Mizuno, Yoshitaka Terada, Hitoshi Inoue, Takayuki Suzuki
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Abstract
An encoder is provided in which the absolute angle can be detected with high accuracy even when the irradiated position of light to be detected with respect to a scale is displaced from a reference, and a photodetecting device for an encoder used for such an encoder. In the encoder 1, by passing light to be detected through a straight-line light transmitting portion 17, a bright portion 19 to which the light to be detected is irradiated is formed in an area of a scale plate 11 containing mutually separate parts of arranged lines L1 and L2 and also a dark portion 20 to which no light to be detected is irradiated is formed in the other area.
Claims10
An encoder comprising:
- a rotating member;
- a light source device for emitting light to be detected to the rotating member;
- and
- a photodetecting device including a scale having a plurality of photodetecting elements arranged thereon, and an output portion for outputting an output signal based on light intensity of the light to be detected made incident to the photodetecting elements through the rotating member, wherein
- the photodetecting elements are arranged along an annularly arranged line on the scale, and
- the rotating member is designed so that, in the scale, an area containing mutually separate parts of the arranged line is set as a bright portion to which the light to be detected is irradiated, and an area containing the other portion excluding the parts of the arranged line concerned is set as a dark portion to which no light to be detected is irradiated,
- wherein the light to be detected is irradiated at, at least, two mutually separated spots of the arranged line.
Dependencies are inferred from the claim text.