Scanning optical system

Filing Information

• Patent Number: US5680244
• Application Number: US8354604
• Filing date: 12/13/1994
• Issue date: 10/21/1997
• Predicted expiration date: 12/13/2014

• U.S. Classifications: 359/205  · 359/206  ·
• International Classifications: G02B 2608 ·
• International Classifications: 359205-208;212-219;662;708;716-718 ·
• Foreign Priority: JP5316757 - 12/16/1993 · JP6195257 - 08/19/1994 ·
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Abstract

A scanning optical system has a deflector and a scanning lens. A convergent beam is deflected at a uniform angular velocity by the deflector. The scanning lens forms the scanned beam into an image on a scanned surface to scan the surface substantially at a uniform velocity. The scanning lens includes from the side of the deflector a negative lens element and at least one more lens element. The convergent beam is incident on a surface of the deflector which faces the deflector. The scanning lens fulfills predetermined conditions.

Independent Claims | See all claims (11)

1. 1. A scanning optical system comprising:a deflector; anda scanning lens on which a convergent beam deflected by the deflector at a uniform angular velocity is incident, said scanning lens forming the convergent beam into an image on a scanned surface to scan the scanned surface substantially at a uniform velocity;wherein said scanning lens includes from a deflector side a first lens element of a negative refractive power and at least one more lens element, and wherein said scanning optical system fulfills the following conditions:C<S1.gtoreq.LY.sup.1 =k.theta. ##EQU15## where S1 is a distance from a deflection surface of the deflector to a natural convergence point of the convergent beam, L is a distance from the deflection surface of the deflector to an image surface, Y' is an image height on the scanned surface, .theta. is a deflection angel, k is a proportional constant, and C is a distance from the deflection surface of the deflector to a thin lens when the scanning lens is represented as one thin lens.
2. 11.11. A scanning optical system for providing a scanning beam comprising:means for generating a beam;means for converging the generated beam;a deflector for reflecting the converging beam; anda scanning lens on which a convergent beam deflected by the deflector at a uniform angular velocity is incident, said scanning lens forming the convergent beam into an image on a scanned surface to scan the scanned surface substantially at a uniform velocity;wherein said scanning lens includes from a deflector side a first lens element of a negative refractive power and at least one more lens element, and wherein said scanning optical system fulfills the following conditions:C<S1.gtoreq.LY.sup.1 =k.theta. ##EQU16## where S1 is a distance from a deflection surface of the deflector to a natural convergence point of the convergent beam, L is a distance from the deflection surface of the deflector to an image surface, Y' is an image height on the scanned surface, .theta. is a deflection angel, k is a proportional constant, and C is a distance from the deflection surface of the deflector to a thin lens when the scanning lens is represented as one thin lens.