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1. WO1989005440 - APPAREIL OPTOELECTRONIQUE DE LECTURE D'ECHELLES DE MESURE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

CLAIKS

1. Opto-electronic scale-reading apparatus comprising:
primary grating means (11,61) defining spaced lines (11A, 61A) and adapted for generating primary orders of diffraction (B) ,
secondary grating means (14;64) defining spaced lines arranged at an angle ( ) to those of the primary grating means thereby to separate each primary order of
diffraction into secondary orders of diffraction (D) .
the primary and secondary grating means cooperating to generate diffraction fringes (C) of differing phases (P0,P1,P2) in a plane (A-A), and
tertiary grating means arranged in said plane and movable relative to at least one of the primary and
- secondary grating means for detecting the respective said phases.

2. Opto-electronic scale-reading apparatus comprising:
grating means (11, 61) defining a scale,
grating means (13, 63) defining an analyser grating, the respective grating means having lines (11A, 61A or 13A, 63A) having a common direction (Y)
illuminating means (10,60) for illuminating one of said grating means (11,61) thereby to generate interferene fringes (C) in a plane (A-A) containing the lines of the other grating means (13,63),
said grating means (11,13 or 61,63) being relatively movable in the sense of causing movement of said fringes (C) across the lines of said other one of the grating means and thereby causing a light modulation (E) ,
phase-separating means (14,64) for separating said modulation into a plurality of phases (P) for generating a quadrature signal 20A, 20B of said modulation,
characterised by (14,64) ,
further grating means (14,64) arranged between said scale and said analyser grating and defined by lines
(14A,64A) lying at an angle a to said conon direction.

3. Opto-electronic scale reading apparatus comprising:
first grating means (11) defining a scale,
a read head (19) adapted for displacement relative to the scale,
second (12) and third (13) grating means provided on the read head,
a light source (10) provided on the read head for illuminating one of the first and second grating means thereby to generate a periodic light pattern (A) ,
the other of the first and second grating means inter-acting with the light pattern for generating
interference fringes (C) in the plane of the third grating means,
said interference fringes having movement relative to said third grating means in accordance with said
displacement thereby to generate a corresponding light modulation (E) ,
said first, second and third grating means each having a periodic structure defined by spaced lines
(11A,12A,13A)
phase-separating means (14) for separating said modulation into a plurality of phases (P) for generating a quadrature signal 20A, 20B of said modulation,
characterised by
fourth grating means (14) positioned between third and said one of the first and second grating means,
the respective lines of said first, second and third grating means lying in a common direction (Y) ,
said fourth grating means being defined by lines (14A) lying at an angle α to said common direction thereby to effect said phase separation.

4. Apparatus according to claim 3 wherein the fourth grating means is situated between the second and third grating means.

5. Apparatus according to claim 3 wherein the fourth grating means is situated between the first and second grating means.

6. Apparatus according to claim 3 wherein the fourth grating means comprises a phase grating.

7. Apparatus according to claim 3 wherein said angle is determined by the expression:
tan α = ΔG/ (G x Δα)
wherein α = said angle,
G = the distance between the fourth
grating means and the one of the
first, second and third grating
means nearest thereto.

Δα = a manufacturing tolerance for the
angle α

ΔG = a manufacturing tolerance for the
distance G.

8. Apparatus according to claim 3 wherein said angle is less than 90 degrees.

9. Apparatus according to claim 3 wherein said one of the first and second gratng means and said fourth grating means co-operate for generating a set of primary
diffraction orders and for generating from each of said primary orders a set of secondary diffraction orders; and the apparatus comprises means for collecting like orders of said sets of secondary orders, and means for detecting said collected like orders.

10. Apparatus according to claim 3 wherein the grating means are arranged for the light from said source to pass in succession through said second, first, fourth and third grating means.

11. Apparatus according to claim 3 wherein the grating means are arranged for the light from said source to pass in succession through said first, second, fourth and third grating means.

12. Apparatus according to claim 3 wherein the grating means are arranged for the light from said source to pass in succession through said first, fourth, second and third grating means.

13. Apparatus according to claim 3 wherein the grating means"are arranged for the" light from said source to pass in succession through said second, fourth, first and third grating means.

14. Apparatus according to claim 11 wherein said second and first grating means co-operate for generating a set of primary diffraction orders (C) said fourth grating means is positioned for generating from each of said primary orders a set (D0,D1,D2) of secondary diffraction orders

(D) ; and the apparatus comprises collecting means (17) for collecting those (DR) of the secondary orders* of the respective sets of secondary orders which have the same direction, and means (18) for detecting respective
collected said orders.

15. Apparatus according to claim 11 wherein said first and second grating means co-operate for generating a set of primary diffraction orders, said fourth grating means is positioned for generating from each of said primary orders a set of secondary diffraction orders; and the apparatus comprises collecting means (17) for collection those (DR) of the orders of the respective sets of
secondary orders which have the same direction, and means for detecting respective collected said orders.

16. Apparatus according to claim 12 wherein said first and fourth grating means co-operate for generating a set of primary diffraction orders, said second grating means is positioned for generating from each of said primary orders a set of secondary diffraction orders; and the apparatus comprises collecting means (15) for collecting those (DR) of the orders of the respective sets of
secondary orders which have the same direction and means (18) for detecting respective collected said orders.

17. Apparatus according to claim 13 wherein said second and fourth grating means co-operate for generating a set of primary diffraction orders, said first grating means is positioned for generating from each of said primary orders a set of secondary diffraction orders; and the apparatus comprises collecting means for collecting those (DR) of the orders of the respective sets of secondary orders which have the same direction and means for detecting respective collected said orders.

18. Apparatus according to any one of claims 14 to 17 wherein said collecting means comprise a decollimating lens means (17) for focussing said secondary orders having the same direction into a respective common focus (0-8) .

19. Apparatus according to claim 18 comprising transducer means (180,181,182) for detecting the respective said foci.

20. Opto-electronic scale-reading apparatus comprising:
first grating means (11) defining a scale,
a read head ( ) adapted for displacement relative to the scale, second grating means ( ) provided on the read head, a source of coherent light provided on the read head for illuminating one of the first grating means for generating interference fringes in th plane of the other one of the first and second grating means,
said interference fringes having movement relative to said other one of the first and second grating means in accordance with said displacement thereby to generate a corresponding light modulation,
said first and second grating means each having a periodic structure defined by spaced lines,
phase-separating means for separating said modulation into a plurality of phases for generating a quadrature signal of said modulation,
characterised by
third grating means positioned between said first and second grating means,
the respective lines of said first and second grating means lying in a common direction, and
said third grating means being defined by lines lying at an angle to said common direction thereby to effect said phase separation.

21. Opto-electronic scale-reading apparatus according to claim 20 wherein said light source and said one of the first and second grating means co-operate for forming a st of primary diffraction orders, said third grating means generating from each of said primary orders a set of secondary diffraction orders; and
the apparatus comprises means for collecting like orders of said sets of of secondary orders, and
means for detecting said collected like orders.

22. Opto-electronic scale-reading apparatus according to claim 21 wherein said collecting means comprise a
decolli ating leans means for focussing said secondary orders having the same direction into a respective common focus.

23. Opto-electronic scale-reading apparatus according to claim 22 comprising transducer means for detecting the respective said foci.