Patent ID: 6542178
Filing Date: 2003-04-01
Classification: B41J,G02B

Abstract:
An image recording apparatus for guiding a light beam to a recording medium and moving the light beam and the recording medium relatively to each other to thereby scan the recording medium with the light beam in main and auxiliary scanning directions to record an image on the recording medium, comprising:a light source for emitting the light beam; a focusing optical system for focusing the light beam emitted from said light source with respect to said recording medium; an optical shaping system for shaping the light beam to shape a beam spot on the recording medium; and plural-focused-positions generating means for generating a plurality of focused positions close to said recording medium along an optical axis of the light beam at least in one of two arbitrary planes, the planes including the optical axis of the light beam and one of the planes being in parallel with the auxiliary scanning direction, and being perpendicular to the other plane; wherein said plural-focused-positions generating means generates focused positions in front of and behind the recording medium for increasing a depth of focus; wherein said plural-focused-positions generating means comprises an optical anisotropic element; wherein said plural-focused-positions generating means is disposed in a divergent or convergent region of said light beam; wherein said plural-focused-positions generating means comprises a uniaxial crystal, said uniaxial crystal forming a crystal plate; wherein said light source comprises a semiconductor laser for emitting a laser beam having a substantially square-shaped intensity distribution with respect to the auxiliary scanning direction, for recording an area-modulated image on the recording medium; and wherein the light beam has a substantially linear shape in which a beam intensity distribution in the main scanning direction is narrower than a beam intensity distribution in the auxiliary scanning direction.