Exposure head and producing method thereof, cartridge, and image forming apparatus
View Patent ↗The invention provides an exposure head including: a light emitting unit; an imaging unit that allows light from the light emitting unit to enter through an incidence plane and exit from an exit surface so as to form an image at a predetermined position; and a transparent layer provided between the light emitting unit and the imaging unit, while contacting each of the light emitting unit and the imaging unit; the transparent layer having a thickness such that an optical distance between the light emitting unit and the incidence plane of the imaging unit becomes a working distance of the imaging unit.
1. An exposure head comprising:
a light emitting unit;
an imaging unit that allows light from the light emitting unit to enter through an incidence surface and exit from an exit surface so as to form an image at a predetermined position; and
a transparent sealing layer provided between the light emitting unit and the imaging unit, while contacting each of an upper surface of the light emitting unit and the imaging unit, wherein
a mounting substrate having an upper surface bound to a lower surface of the transparent sealing layer around a periphery of the light emitting unit,
the transparent sealing layer has a thickness such that an optical distance between the light emitting unit and the incidence surface of the imaging unit becomes a working distance of the imaging unit, and
the light that passes through the imaging unit does not have a focal point within the imaging unit.
2. The exposure head according to claim 1 , wherein the transparent sealing layer comprises a transparent mounting substrate provided integrally with the light emitting unit, and a second transparent layer provided between the transparent mounting substrate and the imaging unit, and
a refractive index difference between the transparent mounting substrate and the second transparent layer is 0.1 or less.
3. The exposure head according to claim 1 , wherein the imaging unit comprises a Selfoc lens array.
4. A cartridge comprising the exposure head according to claim 1 , the cartridge being mounted removably to an image forming apparatus.
5. An image forming apparatus comprising:
a latent image holding member that holds a latent image;
the exposure head according to claim 1 , that forms a latent image by irradiating light on the latent image holding member; and
a developing device that develops the latent image formed by the exposure head.
6. The exposure head according to claim 1 , wherein the light emitting unit is embedded within the mounting substrate.