Patent ID: 8497894
Filing Date: 2013-07-30
Classification: B41J,G02B,G03G

Abstract:
1. An optical scanner that scans a subject to be scanned with a luminous flux in a main-scanning direction, the optical scanner comprising: a light source that includes a plurality of light-emitting elements; an optical deflector that deflects a luminous flux corning from the light source; a scanning lens that collects the luminous flux that has been deflected by the optical deflector, the scanning lens is made of resin; a plurality of reflecting mirrors, wherein each reflecting mirror bends a direction of an optical path of the luminous flux toward the subject to be scanned after the luminous flux passes through the scanning lens; and a dustproof glass that is disposed on the optical path of the luminous flux coming via the reflecting mirrors, wherein one optical element selected from optical elements that include the reflecting mirrors and the dustproof glass has magnitude relation inverse to that of the unselected optical elements and a range larger than those of the unselected optical elements, wherein (A) the magnitude relation of a particular optical element is a relation between a first characteristic value of the particular optical element when the luminous flux travels toward a scanning start position of the subject to be scanned and a second characteristic value of the particular optical element when the luminous flux travels toward a scanning end position of the subject to be scanned, and (B) the range of the particular optical element is a difference between a maximum characteristic value of the particular optical element and a minimum characteristic value of the particular optical element, and wherein in a case that the particular optical element is one of the reflecting mirrors, the characteristic value of the particular optical element is a ratio between (i) a first reflectance of a first luminous flux that has a direction of polarization parallel to a sub-scanning direction and (ii) a second reflectance of a second luminous flux that has a direction of polarization parallel to the main-scanning direction, both the first luminous flux and the second luminous flux being emitted from froth the light source, and in a case that the particular optical element is the dustproof glass, the characteristic value of the particular optical element is a ratio between a first transmittance of the first luminous flux and a second transmittance of the second luminous flux.