Detection apparatus
US8307264B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 28, 2009 |
| Grant date | Nov 6, 2012 |
| Priority date | — |
| Expiry date | Jan 27, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D18/001
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A detection apparatus detecting an error component contained in two signals (A, B) approximated by a cosine and sine functions representing an object position, the detection apparatus including an arithmetic portion (3, 4) which reduces an error contained in the signals (A, B) based on an error prediction value to output two error correction signals (A*, B*), a phase arithmetic portion (5) which calculates a phase (θ) based on the error correction signals (A*, B*), an arithmetic storage unit (9, 10) which stores the error correction signals (A*, B*) and a plurality of sampling values of the phase (θ), and a Fourier transform portion (11, 12) which obtains coefficients αk, βk, γk, and δk in the following two expressions:A*=α0+α1 cos θ+β1 sin θ+ . . . +αk cos kθ+βk sin kθB*=γ0+γ1 cos θ+δ1 sin θ+ . . . +γk cos kθ+δk sin kθ(k≧2)wherein the arithmetic portion (3, 4) updates the error prediction value using the coefficients.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.