US 12,072,216 B2
Encoder apparatus and readhead
Jason Kempton Slack, Wotton-under-Edge (GB); and Julian Alexander Cluff, Wotton-under-Edge (GB)
Assigned to RENISHAW PLC, Wotton-under-Edge (GB)
Appl. No. 17/774,013
Filed by RENISHAW PLC, Wotton-under-Edge (GB)
PCT Filed Nov. 12, 2020, PCT No. PCT/EP2020/081914
§ 371(c)(1), (2) Date May 3, 2022,
PCT Pub. No. WO2021/094456, PCT Pub. Date May 20, 2021.
Claims priority of application No. 1916641 (GB), filed on Nov. 15, 2019.
Prior Publication US 2022/0397430 A1, Dec. 15, 2022
Int. Cl. G01D 5/347 (2006.01); G01B 11/04 (2006.01)
CPC G01D 5/34746 (2013.01) [G01B 11/043 (2013.01); G01D 5/34715 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An encoder apparatus comprising:
a reflective scale; and
a readhead comprising a light emitting element, a sensor and an optical device comprising a lens, which together with the scale form an optical system in which the lens forms an image of an illuminated region of the reflective scale directly onto the sensor, wherein:
the light emitting element is located in a space between the sensor and the lens and is positioned so as to be offset from an optical axis of the lens;
an optical path of the optical system, from the light emitting element to the sensor, i) passes through the lens both toward and after reflection from the scale and ii) comprises an unreflected optical path between the light emitting element and the lens and an unreflected optical path between the lens and the sensor; and
the sensor is tilted such that a sensing plane of the sensor is not perpendicular to the optical axis of the lens.