| 摘要 |
A field replaceable encoder including a slotted housing having a pair of passages therethrough essentially perpendicular to the longitudinal axis of the housing, is attachable to the frame of a machine having a rotatable shaft to which the encoder is to be mounted. Attached to the housing is an accurate stationary mask, the mask having slits which are aligned with the passages in the housing. The mask includes an accurately dimensioned aperture for locating the mask, and thus the housing, on a bearing on the rotatably mounted shaft. A pair of light sources and a pair of light detectors are mounted on opposite sides of the housing aligned with the passages and slits in the mask. A hub, to which is attached a rotating disc, is connected to the rotating shaft, the disc being mounted in the slotted housing so that interdigitated opaque and transparent portions align with the slits of the mask, and thus the light sources and light detectors. In the preferred embodiment, the light sources are mounted in the passages (tunnel like in formation) which converge at their outlets and which prevents having to employ collimated light sources while inhibiting cross-talk between the detectors and adjacent sources allowing for close spacing of the source pair and the detector pair. |
