US4912322A — Optical type displacement detecting device

Claim 1

Independent Claim 186 words

An optical type displacement detecting device comprising: illuminating means including a coherent light source; a main scale having formed thereon a first optical grating with a grating pitch P and the ratio between a light transmitting or reflecting portion and a light shielding or absorbing portion of said first optical grating being substantially 1:1; an index scale located at a position spaced apart by a gap v≃mq 2 /λ from said first grating and having formed thereon a second optical grating with a grating pitch q=P/n and the ratio between a light transmitting portion and a light shielding portion of said second optical grating being substantially 1:1, and wherein m is a whole number of 1 or more, λ is a wavelength at a mean value of the light sensitivity spectra of an optical system, and n in an odd number of 3 or more; and a light receiving element for photoelectrically transducing illuminating light transmitted through said first and second gratings; wherein a detection signal having a pitch P/n is produced in accordance with a relative displacement between said main scale and said index scale.

Claim 2

Dependent Claim 186 words

An optical type displacement detecting device comprising: illuminating means including a coherent light source; a main scale having formed thereon a first optical grating with a grating pitch P and the ratio between a light transmitting or reflecting portion and a light shielding or absorbing portion of said first optical grating being substantially 1:1; an index scale located at a position spaced apart by a gap v≃mq 2 /λ from said first grating and having formed thereon a second optical grating with a grating pitch q=P/n and the ratio between a light transmitting portion and a light shielding portion of said second optical grating being substantially 1:1, and wherein m is a whole number of 1 or more, λ is a wavelength at a mean value of the light sensitivity spectra of an optical system, and n in an odd number of 3 or more; and a light receiving element for photoelectrically transducing illuminating light transmitted through said first and second gratings; wherein a detection signal having a pitch P/n is produced in accordance with a relative displacement between said main scale and said index scale.

Claim 3

Dependent Claim 155 words

An optical type displacement detecting device comprising: a diffusive light source for illuminating a main scale without using a collimator lens; said main scale being located at a position spaced apart by a gap u from said diffusive light source and having formed thereon a first grating with a grating pitch P; an index scale located at a position spaced apart by a gap v≃u(n-0.5)P.sup.2 /{λu-(n-0.5)P.sup.2 } from said first grating and having formed thereon a second grating with a grating pitch q=(u+v)P/(2u), and wherein n is a natural number ≦(λu/P 2 +0.5), and λ is a wavelength at a mean value of the light sensitivity specta of an optical system; and a light receiving element for photoelectrically transducing a change in quantity of light due to overlapping of an image of said first grating by said diffusive light source with said second grating when said main and index scales move relative to each other.

Claim 4

Dependent Claim 155 words

An optical type displacement detecting device comprising: a diffusive light source for illuminating a main scale without using a collimator lens; said main scale being located at a position spaced apart by a gap u from said diffusive light source and having formed thereon a first grating with a grating pitch P; an index scale located at a position spaced apart by a gap v≃u(n-0.5)P.sup.2 /{λu-(n-0.5)P.sup.2 } from said first grating and having formed thereon a second grating with a grating pitch q=(u+v)P/(2u), and wherein n is a natural number ≦(λu/P 2 +0.5), and λ is a wavelength at a mean value of the light sensitivity specta of an optical system; and a light receiving element for photoelectrically transducing a change in quantity of light due to overlapping of an image of said first grating by said diffusive light source with said second grating when said main and index scales move relative to each other.

Claim 5

Dependent Claim 22 words

The optical type displacement detecting device as set forth in claim 2, wherein said diffusive light source is a point light source.

Claim 6

Dependent Claim 21 words

The optical type displacement detecting device as set forth in claim 3, wherein said point light source is a laser diode.

Claim 7

Dependent Claim 41 words

The optical type displacement detecting device as set forth in claim 3, wherein said point light source comprises a laser diode and a lens for controlling a diverging angle disposed in front of a light emitting portion of said laser diode.

Claim 8

Dependent Claim 24 words

The optical type displacement detecting device is set forth in claim 5, wherein said lens for controlling a diverging angle is a hemispherical lens.

Claim 9

Dependent Claim 32 words

The optical type displacement detecting device as set forth in claim 2, wherein said diffusive light source is a linear light source orientated in the direction of width of said first grating.

Claim 10

Dependent Claim 144 words

An optical type displacement detecting device comprising: a diffusive light source; a main scale located at a position spaced apart by a gap u from said diffusive light source and having formed thereon a first grating with a grating pitch P and including higher harmonic components; an index scale located at a position spaced apart by a gap v from said first grating and having formed thereon a second grating with a grating pitch q≃ (u+v) Q/u, when Q=P/m, and wherein m is a whole number of 2 or more; and a light receiving element for photoelectrically transducing a change in quantity of light due to overlapping of an image of said first grating by said diffusive light source with said second grating when said main and index scales move relative to each other, to thereby produce a detection signal of the pitch P.

Claim 11

Dependent Claim 144 words

An optical type displacement detecting device comprising: a diffusive light source; a main scale located at a position spaced apart by a gap u from said diffusive light source and having formed thereon a first grating with a grating pitch P and including higher harmonic components; an index scale located at a position spaced apart by a gap v from said first grating and having formed thereon a second grating with a grating pitch q≃ (u+v) Q/u, when Q=P/m, and wherein m is a whole number of 2 or more; and a light receiving element for photoelectrically transducing a change in quantity of light due to overlapping of an image of said first grating by said diffusive light source with said second grating when said main and index scales move relative to each other, to thereby produce a detection signal of the pitch P.

Claim 12

Dependent Claim 22 words

The optical type displacement dtecting device as set forth in claim 8, wherein said diffusive light source is a point light source.

Claim 13

Dependent Claim 21 words

The optical type displacement detecting device as set forth in claim 9, wherein said point light source is a laser diode.

Claim 14

Dependent Claim 40 words

The optical type displacement device as set forth in claim 9, wherein said point light source comprises a laser diode and a lens for controlling a diverging angle disposed in front of a light emitting portion of said laser diode.

Claim 15

Dependent Claim 24 words

The optical type displacement detecting device as set forth in claim 11, wherein said lens for controlling a diverging angle is a hemispherical lens.

Claim 16

Dependent Claim 32 words

The optical type displacement detecting device as set forth in claim 8, wherein said diffusive light source is a linear light source orientated in the direction of width of said first grating.

Claim 17

Dependent Claim 63 words

The optical type displacement detecting dcevice as set forth in claim 8, wherein said gap v is set at v≃nMQ.sup.2 /λ wherein n is a whole number of 1 or more, when a wavelength at a mean value of the light sensitivity spectra of an optical system is set at λ and a magnification M of said system is defined by M=(u+v) /u.

Claim 18

Dependent Claim 142 words

An optical type displacement detecting device comprising: a diffusive light source; a main scale located at a position spaced apart by a gap u from said diffusive light source and having formed therein a first grating with a grating pitch P and including higher harmonic components; an index scale located at a position spaced apart by a gap v from said first grating and having formed thereon a second grating with a grating pitch of q≃(u+v)Q/(2u) when Q=P/m, wherein m is a whole number of 2 or more; and a light receiving element for photoelectrically transducing a change in quantity of light due to overlapping of an image of said first grating by said diffusive light source with said second grating when said main and index scales more relative to each other, to therby produce a detection signal of a pitch Q/2.

Claim 19

Dependent Claim 142 words

An optical type displacement detecting device comprising: a diffusive light source; a main scale located at a position spaced apart by a gap u from said diffusive light source and having formed therein a first grating with a grating pitch P and including higher harmonic components; an index scale located at a position spaced apart by a gap v from said first grating and having formed thereon a second grating with a grating pitch of q≃(u+v)Q/(2u) when Q=P/m, wherein m is a whole number of 2 or more; and a light receiving element for photoelectrically transducing a change in quantity of light due to overlapping of an image of said first grating by said diffusive light source with said second grating when said main and index scales more relative to each other, to therby produce a detection signal of a pitch Q/2.

Claim 20

Dependent Claim 22 words

the optical type displacement detecting device as set forth in claim 15, wherein said diffusive light source is a point light source.

Claim 21

Dependent Claim 21 words

The optical type displacement detecting device as set forth in claim 16, wherein said point light source is a laser diode.

Claim 22

Dependent Claim 41 words

The optical type displacement detecting device as set forth in claim 15, wherein said point light source comprises a laser diode and a lens for controlling a diverging angle disposed in front of a light emitting portion of said laser diode.

Claim 23

Dependent Claim 24 words

The optical type displacement detecting device as set forth in claim 18, wherein said lens for controlling a diverging angle is a hemispherical lens.

Claim 24

Dependent Claim 32 words

The optical type displacement detecting device as set forth in claim 15, wherein said diffusive light source is a linear light source orientated in the direction of width of said first grating.

Claim 25

Dependent Claim 61 words

The optical type displacement device as set forth in claim 15, wherein said gap v is set at v≃(n-1/2)MQ.sup.2 /λ wherein n is a natural number of 1 or more, when a wavelength at a mean value of the light sensitivity spectra of an optical system is set at λ and a magnification M of said system is defined by M=(u+v)/u.

Claim 26

Dependent Claim 159 words

An optical type displacement detecting device comprising: illuminating means including a coherent light source; a main scale having formed thereon a first optical grating with a grating pitch P and the ratio between a light transmitting or reflecting portion and a light shielding or absorbing portion being substantially 1:1; an index scale located at a position spaced apart by a gap v>100q 2 /λ from said first grating, wherein λ is a wavelength at a mean value of the light sensitivity spectra of an optical system, and said index scale having formed thereon a second optical grating with a grating pitch q=P/2 and the ratio between a light transmitting portion and a light shielding portion being substantially 1:1; and a light receiving element for photoelectrically transducing illuminating light transmitted through said first and second gratings; wherein a detection signal having a pitch P/2 is produced in accordance with a relative displacment between said main scale and said index scale.

Claim 27

Dependent Claim 159 words

An optical type displacement detecting device comprising: illuminating means including a coherent light source; a main scale having formed thereon a first optical grating with a grating pitch P and the ratio between a light transmitting or reflecting portion and a light shielding or absorbing portion being substantially 1:1; an index scale located at a position spaced apart by a gap v>100q 2 /λ from said first grating, wherein λ is a wavelength at a mean value of the light sensitivity spectra of an optical system, and said index scale having formed thereon a second optical grating with a grating pitch q=P/2 and the ratio between a light transmitting portion and a light shielding portion being substantially 1:1; and a light receiving element for photoelectrically transducing illuminating light transmitted through said first and second gratings; wherein a detection signal having a pitch P/2 is produced in accordance with a relative displacment between said main scale and said index scale.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-03-26	1993-09-25	1994-03-27	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-03-26	1997-09-25	1998-03-27	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-03-26	2001-09-25	2002-03-27	$7700.00	Window Closed / Lapsed

Optical type displacement detecting device

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag