Optical printer head and image forming apparatus
View Patent ↗An optical printer head has an array of lenses that project light emitted by an array of LEDs onto a charged photosensitive drum to form a latent image on the drum surface. A resin film adhered to the exposed surfaces of the lenses prevents chemical reaction between nitric acid, formed as a consequence of ozone produced during electric charging of the photosensitive drum, and alkali components on the surfaces of the lenses thereby preventing clouding of the lens surfaces and dimming of the projected light. The resin film has a thickness of 10 to 100 microns and may be formed of polyvinyl chloride, polyethylene terephthalate or polymethyl meta acrylate.
1. An optical printer head comprising:
a light-emitting device that emits light;
a rod lens array that controls light emitted by the light-emitting device;
a frame having opposed frame members that extend along the entire length of the rod lens array and that support therebetween the rod lens array;
a housing in which the light-emitting device is disposed and which supports the frame and the rod lens array above the light-emitting device so that light emitted by the light-emitting device is irradiated on a photosensitive drum during use of the optical printer head; and
a resin film that is 10 to 100 microns thick and that is closely adhered to the surface of an end of the lens array and disposed between the opposed frame members.
2. An optical printer head according to claim 1 ; wherein the resin film is a polyvinyl chloride film, a polyethylene terephthalate film or a polymethyl meta acrylate film.
3. An optical printer head according to claim 1 ; wherein the surface of the lens has thereon an alkali component.
4. An image forming apparatus comprising:
a photosensitive drum;
a charging device that applies a charge having a predetermined potential to a surface of the photosensitive drum;
an optical printer head that irradiates the charged surface of the photosensitive drum with light to form a latent image;
a developing device that develops the latent image to form an image; and
a transfer device that transfers the image to a recording medium,
wherein the optical printer head includes
a light-emitting device that emits light,
a rod lens array that controls light emitted by the light-emitting device,
a frame having opposed frame members that extend along the entire length of the rod lens array and that support therebetween the rod lens array,
a housing in which the light-emitting device is disposed and which supports the frame and the rod lens array above the light-emitting device so that light emitted by the light-emitting device is irradiated on the photosensitive drum, and
a resin film that is 10 to 100 microns thick and that is closely adhered to the surface of the rod lens array and disposed between the opposed frame members.
5. An optical printer head comprising: an enclosed housing having a front side; light-emitting elements disposed in a linear array inside the housing and that emit light directed towards the front side of the housing; a rod lens array having a plurality of rod lenses that are disposed in a linear array in an opening in the front side of the housing and that direct light emitted by the light-emitting elements in a given direction outwardly of the housing; a frame mounted in the opening and supported by the front side of the housing, the frame having opposed frame members that extend along the entire length of the rod lens array and that support therebetween the rod lenses so that they direct light emitted by the light-emitting elements in the given direction; and a resin film having a thickness in the range 10 to 100 microns and adhered to end surfaces of the rod lenses at a location between the opposed frame members to prevent chemical reaction between nitric acid and other components on the end surfaces of the rod lenses.
6. An optical printer head according to claim 5 ; wherein the resin film is a polyvinyl chloride film, a polyethylene terephthalate film or a polymethyl meta acrylate film.
7. An optical printer head according to claim 6 ; wherein the resin film is effective to prevent chemical reaction between nitric acid and an alkali component on the surfaces of the lenses.
8. An optical printer head according to claim 5 ; wherein the resin film is effective to prevent chemical reaction between nitric acid and an alkali component on the surfaces of the lenses.