Abstract This specification discloses a scanning device which is capable of providing a light spot moving at a uniform velocity on a surface to be scanned. The scanning device has a light source, an optical system for receiving the beam from the light source and direct a stationary beam to a deflector for collimating the stationary beam into a scanning parallel beam, and a scanning lens sytem for condensing the scanning parallel beam from the deflector onto the surface to be scanned. The deflector is a transparent polygonal member rotatable about a rotation axis at a constant speed and has a hollow portion whose cross-section orthogonal to the rotation axis is a circle centered at said rotation axis. The optical system causes the stationary beam to impinge at right angles from the rotation axis upon the cylindrical surface formed by the hollow portion. The stationary beam is convergent at the focal line of the cylindrical surface, in the first plane perpendicular to the rotation axis, and is parallel in the second plane perpendicular to the first plane. Thus, the beam emergent from the deflector is parallel both in the first and second planes orthogonal with each other. The scanning lens system has a deflection characteristic expressed as: ##EQU1## where y': the distance between an image of the spot and the optical axis of the scanning lens system. n: refractive index of the polygonal member, f: focal length, θ: angle formed between the scanning parallel beam and the optical axis of said scanning lens system. Because of such strain characteristic of the scanning lens system, there is obtained a light spot moving at a uniform velocity on the scanned surface.
Inventors
👤 Kazuo Minoura
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-28 07:10
CPC Classifications
G; G02; G02B; G02B26/00; G02B26/08; G02B26/10
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
214 words
A scanning device capable of providing a light spot moving at a uniform velocity on a surface to be scanned, comprising: a polygonal member deflector rotatable about a rotation axis at a constant speed, said polygonal member deflector having a transparent polygonal body provided with a cylindrical hollow portion having said rotation axis as its center axis; a light source; an optical system for receiving a beam from said light source and directing the beam, which is stationary, from said center axis to a cylindrical surface formed by cylindrical hollow portion perpendicularly to the cylindrical surface, the stationary beam being convergent at a focal line of the cylindrical surface in a first plane which is perpendicular to the center axis, and being afocal in a second plane perpendicular to the first plane so that an afocal parallel beam is provided from said deflector; a scanning optical system disposed between said polygonal member deflector and said surface, said scanning optical system has a deflection characteristic being expressed as: ##EQU9## where y': the distance between an image of the spot and the optical axis of the scanning lens system, n: refractive index of the polygonal member, f: focal length, θ: angle formed between the scanning parallel beam and the optical axis of said scanning lens system.
Claim 2
Dependent Claim
214 words
A scanning device capable of providing a light spot moving at a uniform velocity on a surface to be scanned, comprising: a polygonal member deflector rotatable about a rotation axis at a constant speed, said polygonal member deflector having a transparent polygonal body provided with a cylindrical hollow portion having said rotation axis as its center axis; a light source; an optical system for receiving a beam from said light source and directing the beam, which is stationary, from said center axis to a cylindrical surface formed by cylindrical hollow portion perpendicularly to the cylindrical surface, the stationary beam being convergent at a focal line of the cylindrical surface in a first plane which is perpendicular to the center axis, and being afocal in a second plane perpendicular to the first plane so that an afocal parallel beam is provided from said deflector; a scanning optical system disposed between said polygonal member deflector and said surface, said scanning optical system has a deflection characteristic being expressed as: ##EQU9## where y': the distance between an image of the spot and the optical axis of the scanning lens system, n: refractive index of the polygonal member, f: focal length, θ: angle formed between the scanning parallel beam and the optical axis of said scanning lens system.
Claim 3
Dependent Claim
26 words
A device according to claim 1, wherein said optical system includes a cylindrical lens and a mirror inclined by 45° with respect to said rotation axis.