Image forming apparatus and light guide member

Abstract

A light guide member has a transmitting/reflecting portion transmitting and reflecting light that is emitted from a light source, to enter one end of the light guide member in a longitudinal direction, and be guided to the other end of the light guide member so that the light is applied to: a position between the developing roller and the transfer roller on the image carrier on a downstream side in the traveling direction of the transfer target member; and a position between the transfer roller and the cleaning portion on the image carrier on an upstream side in the traveling direction of the transfer target member. Furthermore, the light guide member has a convex portion having an arc-shaped cross section and being formed outward at a position opposing the transmitting/reflecting portion in a part of a predetermined specific region at one end or both ends in the longitudinal direction.

The invention claimed is: 
     
       1. An image forming apparatus comprising:
 a plurality of image carriers arranged along a traveling direction of a transfer target member; 
 a developing roller configured to develop an electrostatic latent image formed on each image carrier as a toner image; 
 a transfer roller configured to transfer the toner image formed on each image carrier onto the transfer target member; 
 a cleaning portion configured to clean each image carrier after the toner image is transferred onto the transfer target member by the transfer roller; 
 a light source configured to emit light used to discharge each image carrier; and 
 an elongated light guide member having a transmitting/reflecting portion and a convex portion, the transmitting/reflecting portion transmitting and reflecting light that is emitted from the light source, to enter one end of the light guide member in a longitudinal direction, and be guided to the other end of the light guide member so that the light is applied to: a position between the developing roller and the transfer roller on the image carrier on a downstream side in the traveling direction of the transfer target member; and a position between the transfer roller and the cleaning portion on the image carrier on an upstream side in the traveling direction of the transfer target member, the convex portion having an arc-shaped cross section and being formed outward at a position opposing the transmitting/reflecting portion in a part of a predetermined specific region at one end or both ends in the longitudinal direction, wherein 
 the light guide member is an elongated member that has one flat surface having a plurality of the transmitting/reflecting portions. 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein the specific region is a region that corresponds to a non-image formation region of the image carrier. 
     
     
       3. The image forming apparatus according to  claim 1 , wherein the light guide member is an elongated member that has one flat surface having a plurality of the transmitting/reflecting portions formed along the longitudinal direction at predetermined intervals. 
     
     
       4. The image forming apparatus according to  claim 3 , wherein the transmitting/reflecting portions are inclined surfaces that are formed inwardly from the flat surface at a predetermined inclination angle. 
     
     
       5. The image forming apparatus according to  claim 3 , wherein the intervals of the transmitting/reflecting portions become shorter as a distance from the light source becomes longer. 
     
     
       6. The image forming apparatus according to  claim 3 , wherein the sizes of the transmitting/reflecting portions become larger as a distance from the light source becomes longer. 
     
     
       7. The image forming apparatus according to  claim 1 , further comprising a light-transmitting member that covers a part or the entirety of an outer periphery of the light guide member. 
     
     
       8. The image forming apparatus according to  claim 1 , wherein
 the image carrier disposed on a most upstream side in the traveling direction is an image carrier for yellow; and 
 the light source and the light guide member are disposed only at positions on a downstream side of each image carrier in the traveling direction. 
 
     
     
       9. An elongated light guide member used in an image forming apparatus including: a plurality of image carriers arranged along a traveling direction of a transfer target member; a developing roller configured to develop an electrostatic latent image formed on each image carrier as a toner image; a transfer roller configured to transfer the toner image formed on each image carrier onto the transfer target member; a cleaning portion configured to clean each image carrier after the toner image is transferred onto the transfer target member by the transfer roller; and a light source configured to emit light used to discharge each image carrier,
 the light guide member having a transmitting/reflecting portion and a convex portion, the transmitting/reflecting portion transmitting and reflecting light that is emitted from the light source, to enter one end of the light guide member in a longitudinal direction, and be guided to the other end of the light guide member so that the light is applied to: a position between the developing roller and the transfer roller on the image carrier on a downstream side in the traveling direction of the transfer target member; and a position between the transfer roller and the cleaning portion on the image carrier on an upstream side in the traveling direction of the transfer target member, the convex portion having an arc-shaped cross section and being formed outward at a position opposing the transmitting/reflecting portion in a part of a predetermined specific region at one end or both ends in the longitudinal direction, the light guide member being an elongated member that has having one flat surface having with a plurality of the transmitting/reflecting portions. 
 
     
     
       10. An image forming apparatus comprising:
 a plurality of image carriers arranged along a traveling direction of a transfer target member;   a developing roller configured to develop an electrostatic latent image formed on each image carrier as a toner image;   a transfer roller configured to transfer the toner image formed on each image carrier onto the transfer target member;   a cleaning portion configured to clean each image carrier after the toner image is transferred onto the transfer target member by the transfer roller;   a light source configured to emit light used to discharge each image carrier; and   an elongated light guide member having a transmitting/reflecting portion, the transmitting/reflecting portion transmitting and reflecting light that is emitted from the light source, to enter one end of the light guide member in a longitudinal direction, and be guided to the other end of the light guide member so that the light is applied to: a position between the developing roller and the transfer roller on the image carrier on a downstream side in the traveling direction of the transfer target member; and a position between the transfer roller and the cleaning portion on the image carrier on an upstream side in the traveling direction of the transfer target member, wherein   the light guide member has one flat surface having a plurality of the transmitting/reflecting portions.   
     
     
       11. An elongated light guide member used in an image forming apparatus including: a plurality of image carriers arranged along a traveling direction of a transfer target member; a developing roller configured to develop an electrostatic latent image formed on each image carrier as a toner image; a transfer roller configured to transfer the toner image formed on each image carrier onto the transfer target member; a cleaning portion configured to clean each image carrier after the toner image is transferred onto the transfer target member by the transfer roller; and a light source configured to emit light used to discharge each image carrier,
 the light guide member having a transmitting/reflecting portion, the transmitting/reflecting portion transmitting and reflecting light that is emitted from the light source, to enter one end of the light guide member in a longitudinal direction, and be guided to the other end of the light guide member so that the light is applied to: a position between the developing roller and the transfer roller on the image carrier on a downstream side in the traveling direction of the transfer target member; and a position between the transfer roller and the cleaning portion on the image carrier on an upstream side in the traveling direction of the transfer target member, the light guide member having one flat surface with a plurality of the transmitting/reflecting portions.   
     
     
       12. An image forming unit comprising:
 a first image carrier;   a developing roller configured to develop an electrostatic latent image formed on the first image carrier as a toner image;   a first transfer roller configured to transfer the toner image formed on the first image carrier onto a transfer target member;   a cleaning portion configured to clean the first image carrier after the toner image is transferred onto the transfer target member by the first transfer roller;   a light source configured to emit light used to discharge the first image carrier; and   an elongated light guide member having a transmitting/reflecting portion, the transmitting/reflecting portion transmitting and reflecting light that is emitted from the light source, to enter one end of the light guide member in a longitudinal direction, and be guided to the other end of the light guide member so that the light is applied to: a position between the developing roller and the first transfer roller on the first image carrier; and a position between a second transfer roller and a second cleaning portion on a second image carrier of another image forming unit disposed on an upstream side in a traveling direction of the transfer target member, the light guide member having one flat surface with a plurality of the transmitting/reflecting portions.