Inner drum exposure device
The present invention provides an inner drum exposure device. Based on image signals from two light sources, two laser beams, which are each made independent, modulated, and projected, are polarized and integrated with a polarized light beam splitter, and then made into right-handed and left-handed circularly polarized light and projected towards a scanning optical system. This right-handed and left-handed circularly polarized light incident from the light source side optical system are converted to two linearly polarized laser beams that cross each other with a quarter wavelength plate arranged on the optical path of the scanning optical system. After this, the two laser beams converted with the quarter wavelength plate into linearly polarized light that cross each other are ejected, each from differing positions such that the primary rays of the projected beams are parallel, with a uniaxial crystal.
1 . An inner drum exposure device comprising:
an optical system on a light source side that, with a polarized light beam splitter, polarizes and integrates two laser beams that are each made independent, modulated, and projected based on image signals from the light source side, and that makes the two laser beams into right-handed circularly polarized light and left-handed circularly polarized light and projects them towards a scanning optical system;
a quarter wavelength plate set on an optical path of the scanning optical system that converts the right-handed circularly polarized light and left-handed circularly polarized light incident from the light source side optical system into linearly-polarized light such that the two laser beams cross each other; and
a uniaxial crystal that projects the two laser beams that were converted with the quarter wavelength plate into linearly-polarized light that cross each other such that the ejected beams of principal rays are each projected from differing positions parallel to one another.
2 . The inner drum exposure device of claim 1 , wherein the quarter wavelength plate and the uniaxial crystal are made to be uniform and set at a rotational axis component of an optical deflector arranged at the scanning optical system.
3 . The inner drum exposure device of claim 1 , wherein the uniaxial crystal is formed into a planar plate and the direction of the refractive index of extraordinary light is inclined relative to the normal line of the incident surface.
4 . The inner drum exposure device of claim 1 , wherein the angle of inclination of the refractive index of extraordinary light is approximately 45°.
5 . The inner drum exposure device of claim 1 , wherein the quarter wavelength plate and the uniaxial crystal are made to be uniform and rotatably and adjustably attached relative to a reflective surface provided at the rotational axis component of the optical deflector arranged at the scanning optical system.
6 . The inner drum exposure device of claim 1 further comprising:
a detecting component arranged so as to detect the positions of each focusing spot of the two laser beams polarized and integrated with the polarized light beam splitter of the optical system on the light source side; and
an adjusting component, arranged at the optical system of the light source side, that adjusts the angle of at least one laser beam and adjusts so that a position difference between the two laser beams detected with the detecting component becomes a preset value.
7 . The inner drum exposure device of claim 6 , wherein the adjusting component that adjusts the angle of the laser beam performs adjustment when a recording medium is not being exposure recorded.
8 . The inner drum exposure device of claim 1 , wherein a polarized light control element that controls the direction of each polarized light beam and a splitting element that splits each light beam that passes through the polarized light control element in the sub-scanning direction are at the optical path, on the downstream side from the quarter wavelength plate arranged on the optical path of the scanning optical system and the uniaxial crystal, and the polarized light control element is arranged so as to split each light beam in the sub-scanning direction with the splitting element at approximately uniform luminosities.
9 . The inner drum exposure device of claim 8 , wherein the polarized light control element is a half wavelength plate and the splitting element is a uniaxial crystal.
10 . The inner drum exposure device of claim 1 , wherein the uniaxial crystal is quartz.