Abstract: A relative position detection method detecting a position of a light-emitting member relative to a lens array or a position of the lens array relative to the light-emitting member, in which the light-emitting member includes light-emitting elements arranged in a first direction and the lens array includes lenses arranged in the first direction and condenses light from the light-emitting elements to image positions of the light-emitting elements, optical axes of the lenses being orthogonal to the first direction. The method includes: causing the light-emitting elements to emit light; detecting, at a position displaced from the image positions along an optical axis direction, optical intensity distribution of light emitted from the light-emitting elements and transmitted through the lens array; and detecting a position of the light-emitting member relative to the lens array or a position of the lens array relative to the light-emitting member with use of the optical intensity distribution.

Abstract: A relative position detection method detecting a position of a light-emitting member relative to a lens array or a position of the lens array relative to the light-emitting member, in which the light-emitting member includes light-emitting elements arranged in a first direction and the lens array includes lenses arranged in the first direction and condenses light from the light-emitting elements to image positions of the light-emitting elements, optical axes of the lenses being orthogonal to the first direction. The method includes: causing the light-emitting elements to emit light; detecting, at a position displaced from the image positions along an optical axis direction, optical intensity distribution of light emitted from the light-emitting elements and transmitted through the lens array; and detecting a position of the light-emitting member relative to the lens array or a position of the lens array relative to the light-emitting member with use of the optical intensity distribution.

Abstract: An optical writing device having; a plurality of light-emitting points; a photodiode configured to output a signal which represents a quantity of incident light from a predetermined light-emitting point selected from the plurality of light-emitting points; and a calculation section for calculating a temperature of the photodiode based on a magnitude of a photodiode dark current included in the signal output from the photodiode while the predetermined light-emitting point is OFF.

Abstract: A light-emitting element having a light-emitting section and a light-receiving section provided on a substrate. The light-emitting section includes: an organic compound in which light is emitted; a translucent reflecting portion that transmits the emitted light which has spectral radiance changeable with changes in ambient temperature; and a transparent portion that radiates first part of the light coming through the translucent reflecting portion to outside and total-reflects second part that is light incident to a boundary surface therebetween at angles larger than a critical angle. Wherein, the light-receiving section is capable of receiving the light total-reflected at the boundary surface, the received light having a quantity of light changeable with changes in wavelength of the light passing through the translucent reflecting portion. The light-receiving section further outputs a signal which has an amplitude level in correlation to the quantity of light.

Abstract: Provided is a deposition apparatus that has a metal evaporation source for depositing a reflective layer, a pigment evaporation source for depositing a coloring layer, and a plasma polymerization source (electrode) for depositing a protective layer disposed inside a single vacuum processing room. By carrying out a step of depositing the reflective layer, a step of depositing the coloring layer, and a step of depositing the protective layer in the common vacuum processing room, processes can be simplified and an operation time can be reduced.