Loading patent…
AssigneeGEC-Marconi Limited
InventorDuncan P. Rowe
Estimating the term…
The relative position (M) of two members (33, 34) is sensed by scanning (S) an optical beam (25) over an encoded pattern (20) carried by one of the members, and by using a read head (21) secured to the other member to receive an optical signal transmitted from the encoded pattern (20). This optical signal is received by an optical position sensor to discriminate from the frequency of the signal, the position of the read head (21) relative to the encoded pattern (20). As the relative position is detected from the frequency of the signal rather than its intensity, components can be replaced without recalibration. The optical beam (25) is scanned by using a light source of variable wavelength which is passed through a device, such as a diffraction grating or a gradient index lens, for deflecting the beam (25) dependent on its wavelength.
Position sensing apparatus, for sensing the relative position of two members, including an encoded pattern carried by one of said members, means for producing an optical beam of varying wavelength, scanning means for deflecting said beam dependent on its wavelength to scan over said encoded pattern, said encoded pattern being arranged to transmit part of said beam as an optical signal, a readhead secured to said other member to receive said optical signal and an optical position sensor to receive said optical signal from said readhead and to discriminate, from the frequency of said optical signal, the position of said readhead relative to said encoded pattern and consequently the relative position of said members.
Position sensing apparatus, as in claim in which said encoded pattern varies in regular increments in the direction or sense of movement between said two members, and said scanning means is arranged to scan said optical beam transversely to such direction or sense of movement.
A method of sensing the relative position of two members, including providing an optical beam of variable wavelength, refracting the beam dependent on its wavelength to scan, from a fixed position relative to one of said members, over an encoded pattern carried by the other of said members to produce an optical signal, and detecting the portion of said encoded pattern over which the optical beam has been scanned by sensing the frequency of the optical signal.
Dependencies are inferred from the claim text.