Scanning optical apparatus and method for manufacturing reflection member

Abstract

A scanning optical apparatus includes: a deflection unit configured to deflect a light flux from a light source in a main scanning direction; an incident optical system configured to introduce the light flux from the light source to the deflection unit; a condensing optical system configured to condense the light flux from the deflection unit onto a scanned surface; and a reflection member arranged in a light path of the light flux deflected in the main scanning direction by the deflection unit and configured to reflect a part of the deflected light flux. The reflection member has a reflection surface configured to reflect the deflected light flux, a first end surface formed in the main scanning direction, and a second end surface formed in a sub-scanning direction perpendicular to the main scanning direction, and the second end surface has a higher degree of corrosion resistance than the first end surface.

What is claimed is: 
     
         1 . A scanning optical apparatus comprising:
 a deflection unit configured to deflect a light flux from a light source in a main scanning direction;   an incident optical system ( 2 ,  3 ,  4 ) configured to introduce the light flux from the light source to the deflection unit;   a condensing optical system ( 6 ) configured to condense the light flux from the deflection unit onto a scanned surface; and   a reflection member ( 9 ) arranged in a light path of the light flux deflected in the main scanning direction by the deflection unit and configured to reflect a part of the deflected light flux, wherein   the reflection member has a reflection surface configured to reflect the deflected light flux, a first end surface formed in the main scanning direction, and a second end surface formed in a sub-scanning direction perpendicular to the main scanning direction, and   the second end surface has a higher degree of corrosion resistance than the first end surface.   
     
     
         2 . The scanning optical apparatus according to  claim 1 , wherein the first end surface is a surface left unchanged since cutting after formation of a reflection coating on the reflection surface, and the second end surface is a surface left unchanged since cutting before formation of the reflection coating. 
     
     
         3 . The scanning optical apparatus according to  claim 1 , wherein the first end surface is a surface left unchanged since cutting, and the second end surface is a surface coated with a corrosion inhibitor. 
     
     
         4 . The scanning optical apparatus according to  claim 1 , wherein a length of the reflection surface of the reflection member in the main scanning direction is different from a length of the reflection surface of the reflection member in the sub-scanning direction. 
     
     
         5 . The scanning optical apparatus according to  claim 4 , wherein a length of the reflection surface of the reflection member in the main scanning direction is larger than a length of the reflection surface of the reflection member in the sub-scanning direction. 
     
     
         6 . The scanning optical apparatus according to  claim 1 , wherein the reflection member is a part of a synchronous detection unit and is configured to separate a light flux directed to a sensor surface as a synchronous detection light flux from the light flux directed to the scanned surface. 
     
     
         7 . The scanning optical apparatus according to  claim 1 , wherein the light flux deflected in the main scanning direction passes through a plane including the second end surface. 
     
     
         8 . The scanning optical apparatus according to  claim 1 , wherein the reflection member is a member obtained by cutting a mirror, which is provided with a reflection coating, along at least one cut surface parallel with a transverse direction, and
 a pre-cutting longitudinal direction of the mirror coincides with the sub-scanning direction.   
     
     
         9 . The scanning optical apparatus according to  claim 1 , wherein the reflection member is a member obtained by cutting a mirror, which is provided with a reflection coating on a surface corresponding to the reflection surface, along at least one cut surface parallel with a transverse direction of the mirror, without cutting the mirror in a direction parallel with a longitudinal direction of the mirror, and
 a pre-cutting longitudinal direction of the mirror is parallel with the sub-scanning direction, and a pre-cutting transverse direction of the mirror is parallel with the main scanning direction.   
     
     
         10 . The scanning optical apparatus according to  claim 1 , wherein the light flux deflected in the main scanning direction is a plurality of light fluxes. 
     
     
         11 . An image forming apparatus comprising:
 the scanning optical apparatus according to  claim 1 ;   a photosensitive body arranged on the scanned surface;   a developing unit configured to develop, as a toner image, an electrostatic latent image formed on the photosensitive body by the light flux deflected by the scanning optical apparatus;   a transferring unit configured to transfer the developed toner image to a transferred material; and   a fixing unit configured to fix the transferred toner image to the transferred material.   
     
     
         12 . An image forming apparatus comprising:
 the scanning optical apparatus according to  claim 1 ; and   a printer controller configured to convert code data input from an external apparatus into an image signal and input the image signal to the scanning optical apparatus.   
     
     
         13 . A method for manufacturing a reflection member of a scanning optical apparatus including:
 a deflection unit configured to deflect a light flux from a light source in a main scanning direction;   an incident optical system ( 2 ,  3 ,  4 ) configured to introduce the light flux from the light source to the deflection unit;   a condensing optical system ( 6 ) configured to condense the light flux from the deflection unit onto a scanned surface; and   a reflection member ( 9 ) arranged in a light path of the light flux deflected in the main scanning direction by the deflection unit and configured to reflect a part of the deflected light flux, the method comprising:   cutting a reflection optical substrate in a first cutting direction corresponding to a direction parallel with a sub-scanning direction perpendicular to the main scanning direction and obtaining a first optical member piece ( 930 ) of a rectangular shape elongated in the first cutting direction;   forming a reflection coating on a reflection optical surface of the first optical member piece ( 930 ); and   cutting the first optical member piece ( 930 ) in a second cutting direction corresponding to a direction parallel with the main scanning direction and obtaining a second optical member piece ( 9 ′) as the reflection member.   
     
     
         14 . A method for manufacturing a scanning optical apparatus including:
 a deflection unit configured to deflect a light flux from a light source in a main scanning direction;   an incident optical system ( 2 ,  3 ,  4 ) configured to introduce the light flux from the light source to the deflection unit;   a condensing optical system ( 6 ) configured to condense the light flux from the deflection unit onto a scanned surface; and   a reflection member ( 9 ) arranged in a light path of the light flux deflected in the main scanning direction by the deflection unit and configured to reflect a part of the deflected light flux, the method comprising:   cutting a reflection optical substrate in a first cutting direction corresponding to a direction parallel with a sub-scanning direction perpendicular to the main scanning direction and obtaining a first optical member piece ( 930 ) of a rectangular shape elongated in the first cutting direction;   forming a reflection coating on a reflection optical surface of the first optical member piece ( 930 );   cutting the first optical member piece ( 930 ) in a second cutting direction corresponding to a direction parallel with the main scanning direction and obtaining a second optical member piece ( 9 ′) as the reflection member; and   embedding the second optical member piece in a housing of the scanning optical apparatus.   
     
     
         15 . A method for manufacturing a reflection member of a scanning optical apparatus including:
 a deflection unit configured to deflect a light flux from a light source in a main scanning direction;   an incident optical system ( 2 ,  3 ,  4 ) configured to introduce the light flux from the light source to the deflection unit;   a condensing optical system ( 6 ) configured to condense the light flux from the deflection unit onto a scanned surface; and   a reflection member ( 9 ) arranged in a light path of the light flux deflected in the main scanning direction by the deflection unit and configured to reflect a part of the deflected light flux, the method comprising:   forming a reflection coating ( 942 ) on a reflection optical surface of a reflection optical substrate ( 941 );   cutting the reflection optical substrate ( 941 ), on which the reflection coating has been formed, in a first cutting direction corresponding to a direction parallel with a sub-scanning direction perpendicular to the main scanning direction and obtaining a first optical member piece ( 943 ) of a rectangular shape elongated in the first cutting direction;   applying a corrosion inhibitor to an end surface ( 944 ) of the first optical member piece ( 943 ) cut in the first cutting direction; and   cutting the first optical member piece ( 943 ) in a second cutting direction corresponding to a direction parallel with the main scanning direction and obtaining a second optical member piece ( 9 ′) as the reflection member.   
     
     
         16 . A method for manufacturing a scanning optical apparatus including:
 a deflection unit configured to deflect a light flux from a light source in a main scanning direction;   an incident optical system ( 2 ,  3 ,  4 ) configured to introduce the light flux from the light source to the deflection unit;   a condensing optical system ( 6 ) configured to condense the light flux from the deflection unit onto a scanned surface; and   a reflection member ( 9 ) arranged in a light path of the light flux deflected in the main scanning direction by the deflection unit and configured to reflect a part of the deflected light flux, the method comprising:   forming a reflection coating ( 942 ) on a reflection optical surface of a reflection optical substrate ( 941 );   cutting the reflection optical substrate ( 941 ), on which the reflection coating has been formed, in a first cutting direction corresponding to a direction parallel with a sub-scanning direction perpendicular to the main scanning direction and obtaining a first optical member piece ( 943 ) of a rectangular shape elongated in the first cutting direction;   applying a corrosion inhibitor to an end surface ( 944 ) of the first optical member piece ( 943 ) cut in the first cutting direction;   cutting the first optical member piece ( 943 ) in a second cutting direction corresponding to a direction parallel with the main scanning direction and obtaining a second optical member piece ( 9 ′) as the reflection member; and   embedding the second optical member piece in a housing of the scanning optical apparatus.   
     
     
         17 . The method according to  claim 13 , wherein formation of the reflection coating is performed by vacuum deposition or sputtering.