Optical sensor and image forming apparatus

Abstract

An optical sensor includes at least one light emitting unit that emits a light, a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, and a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object. The sum of the incident angle and the reflection angle is 25 degrees or less.

What is claimed is:  
     
         1 . An optical sensor comprising: 
 at least one light emitting unit that emits a light;    a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and    a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein    a sum of the incident angle and the reflection angle is 25 degrees or less.    
     
     
         2 . The optical sensor according to  claim 1 , wherein the sum of the incident angle and the reflection angle is 20 degrees or less.  
     
     
         3 . The optical sensor according to  claim 1 , further comprising a traveling direction changing unit that changes a traveling direction of the light provided on at least one of incident light path and specular reflection light path.  
     
     
         4 . The optical sensor according to  claim 1 , wherein a light condensing member is provided on at least one of incident light path and specular reflection light path such that optical axis of the light condensing member matches with center line of the at least one of the incident light path and the specular reflection light path.  
     
     
         5 . The optical sensor according to  claim 1 , wherein a light diffusing member is provided on the specular reflection light path.  
     
     
         6 . The optical sensor according to  claim 1 , wherein at least one of the at least one light emitting unit and the first light receiving unit is formed by a surface mounted optical means in which an optical element is surface mounted on a substrate.  
     
     
         7 . The optical sensor according to  claim 1 , wherein the at least one light emitting unit and the first light receiving unit are sealed in a single package.  
     
     
         8 . The optical sensor according to  claim 1 , wherein a spot size of the light from the at least one light emitting unit is larger than a spot size of the specular reflection light entering the first light receiving unit.  
     
     
         9 . The optical sensor according to  claim 1 , wherein the second light receiving unit is disposed outside of a virtual plane including incident light path along which the light from the light emitting unit travels to the illumination object and the specular reflection light path along which the specular reflection light travels to the first light receiving unit.  
     
     
         10 . An optical sensor comprising: 
 at least one light emitting unit that emits a light;    a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and    a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein    a light condensing member is provided on at least one of incident light path along which the light from the light emitting unit travels to the illumination object, a specular reflection light path along which the specular reflection light travels to the first light receiving unit, and diffuse reflection light path along which the diffuse reflection light travels to the second light receiving unit.    
     
     
         11 . The optical sensor according to  claim 10 , wherein the light condensing member is provided on both the incident light path and the specular reflection light path.  
     
     
         12 . The optical sensor according to  claim 10 , wherein, the light condensing member is disposed to satisfy following equation  
       1 /a+ 1 /b= 1 /f    
       where a is a distance from a start point of the at least one light path to the light condensing member, b is a distance from the light condensing member to an end point of the at least one light path, and f is a focal distance of the light condensing member.  
     
     
         13 . The optical sensor according to  claim 10 , wherein a light diffusing member is provided on the specular reflection light path.  
     
     
         14 . The optical sensor according to  claim 10 , wherein a surface of at least one of the light condensing member and the light diffusing member on a side opposite to the illumination object is a flat surface.  
     
     
         15 . The optical sensor according to  claim 10 , wherein the at least one light emitting unit and the first light receiving unit are sealed in a single package.  
     
     
         16 . The optical sensor according to  claim 10 , wherein a spot size of the light from the at least one light emitting unit is larger than a spot size of the specular reflection light entering the first light receiving unit.  
     
     
         17 . The optical sensor according to  claim 10 , wherein the second light receiving unit is disposed outside of a virtual plane including incident light path along which the light from the light emitting unit travels to the illumination object and the specular reflection light path along which the specular reflection light travels to the first light receiving unit.  
     
     
         18 . An optical sensor comprising: 
 at least one light emitting unit that emits a light;    a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and    a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein    the at least one of the at least one light emitting unit and the first light receiving unit is formed by a surface mounted optical means in which an optical element is surface mounted on a substrate.    
     
     
         19 . The optical sensor according to  claim 18 , wherein the at least one light emitting unit and the first light receiving unit are sealed in a single package.  
     
     
         20 . The optical sensor according to  claim 18 , wherein an optical element of the at least one light emitting unit and an optical element of the first light receiving unit are mounted on opposite surfaces of same substrate.  
     
     
         21 . The optical sensor according to  claim 18 , wherein 
 both the at least one light emitting unit and the first light receiving unit are formed by the surface mounted optical means,    an optical element of the at least one light emitting unit and an optical element of the first light receiving unit are surface mounted on a same surface of same substrate, and    a light-shielding means is provided on a virtual line connecting the optical elements.    
     
     
         22 . The optical sensor according to  claim 18 , wherein 
 both the at least one light emitting unit and the first light receiving unit are formed by the surface mounted optical means,    an optical element of the at least one light emitting unit and an optical element of the first light receiving unit are surface mounted on a same surface of same substrate, and    a through hole is provided in a surface of the substrate on a virtual line connecting the optical elements.    
     
     
         23 . The optical sensor according to  claim 18 , wherein elements mounted on the surface mounted optical means are laid out not to block a light path.  
     
     
         24 . The optical sensor according to  claim 18 , wherein elements of the surface mounted optical means are surface mounted on the substrate opposite to a light path.  
     
     
         25 . The optical sensor according to  claim 18 , wherein a spot size of the light from the at least one light emitting unit is larger than a spot size of the specular reflection light entering the first light receiving unit.  
     
     
         26 . The optical sensor according to  claim 18 , wherein the second light receiving unit is disposed outside of a virtual plane including incident light path along which the light from the light emitting unit travels to the illumination object and the specular reflection light path along which the specular reflection light travels to the first light receiving unit.  
     
     
         27 . An optical sensor comprising: 
 at least one light emitting unit that emits a light;    a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and    a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein    the second light receiving unit is disposed outside of a virtual plane including incident light path along which the light from the light emitting unit travels to the illumination object and the specular reflection light path along which the specular reflection light travels to the first light receiving unit.    
     
     
         28 . The optical sensor according to  claim 27 , wherein 
 both an optical element of the at least one light emitting unit and an optical element of the first light receiving unit are mounted on same surface of a substrate, and    an optical element of the second light receiving unit is mounted on a surface of the substrate opposite to the same surface.    
     
     
         29 . The optical sensor according to  claim 27 , wherein a lead wire of the optical element of the second light receiving unit is soldered to the substrate.  
     
     
         30 . The optical sensor according to  claim 27 , wherein 
 a casing is provided surrounding an area of diffuse reflection light path along which diffuse reflection light travels, the area near the second light receiving unit, and    a reflection surface that reflects the diffuse reflection light is provided on an inner wall of the casing.    
     
     
         31 . The optical sensor according to  claim 27 , wherein 
 a casing is provided surrounding an area of diffuse reflection light path along which diffuse reflection light travels, the area near the second light receiving unit, and    a light transmitting member is provided at an inlet opening for the diffuse reflection light to enter the casing.    
     
     
         32 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light;  
 a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and  
 a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein  
 a sum of the incident angle and the reflection angle is 25 degrees or less.  
   
     
     
         33 . The image formation apparatus according to  claim 32 , wherein a weight average particle diameter of the toner is 8 micrometers or less.  
     
     
         34 . The image formation apparatus according to  claim 32 , wherein an average roundness of the toner is 0.93 or more.  
     
     
         35 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light;  
 a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and  
 a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein  
 a light condensing member is provided on at least one of incident light path along which the light from the light emitting unit travels to the illumination object, a specular reflection light path along which the specular reflection light travels to the first light receiving unit, and diffuse reflection light path along which the diffuse reflection light travels to the second light receiving unit.  
   
     
     
         36 . The image formation apparatus according to  claim 35 , wherein a weight average particle diameter of the toner is 8 micrometers or less.  
     
     
         37 . The image formation apparatus according to  claim 35 , wherein an average roundness of the toner is 0.93 or more.  
     
     
         38 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light;  
 a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and  
 a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein  
 the at least one of the at least one light emitting unit and the first light receiving unit is formed by a surface mounted optical means in which an optical element is surface mounted on a substrate.  
   
     
     
         39 . The image formation apparatus according to  claim 38 , wherein a weight average particle diameter of the toner is 8 micrometers or less.  
     
     
         40 . The image formation apparatus according to  claim 38 , wherein an average roundness of the toner is 0.93 or more.  
     
     
         41 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light;  
 a first light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle; and  
 a second light receiving unit that receives diffuse reflection light from the illumination object when the incident light is diffusely reflected at the illumination object, wherein  
 the second light receiving unit is disposed outside of a virtual plane including incident light path along which the light from the light emitting unit travels to the illumination object and the specular reflection light path along which the specular reflection light travels to the first light receiving unit.  
   
     
     
         42 . The image formation apparatus according to  claim 41 , wherein a weight average particle diameter of the toner is 8 micrometers or less.  
     
     
         43 . The image formation apparatus according to  claim 41 , wherein an average roundness of the toner is 0.93 or more.  
     
     
         44 . An optical sensor comprising: 
 at least one light emitting unit that emits a light; and    a light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein    a sum of the incident angle and the reflection angle is 25 degrees or less.    
     
     
         45 . The optical sensor according to  claim 44 , wherein the sum of the incident angle and the reflection angle is 20 degrees or less.  
     
     
         46 . The optical sensor according to  claim 44 , further comprising a traveling direction changing unit that changes a traveling direction of the light provided on at least one of incident light path and specular reflection light path.  
     
     
         47 . The optical sensor according to  claim 44 , wherein a light condensing member is provided on at least one of incident light path and specular reflection light path such that optical axis of the light condensing member matches with center line of the at least one of the incident light path and the specular reflection light path.  
     
     
         48 . The optical sensor according to  claim 44 , wherein a light diffusing member is provided on the specular reflection light path.  
     
     
         49 . The optical sensor according to  claim 44 , wherein at least one of the at least one light emitting unit and the light receiving unit is formed by a surface mounted optical means in which an optical element is surface mounted on a substrate.  
     
     
         50 . The optical sensor according to  claim 44 , wherein the at least one light emitting unit and the light receiving unit are sealed in a single package.  
     
     
         51 . An optical sensor comprising: 
 at least one light emitting unit that emits a light; and    a light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein    a light condensing member is provided on at least one of incident light path along which the light from the light emitting unit travels to the illumination object, a specular reflection light path along which the specular reflection light travels to the light receiving unit, and diffuse reflection light path along which the diffuse reflection light travels to the second light receiving unit.    
     
     
         52 . The optical sensor according to  claim 51 , wherein, the light condensing member is disposed to satisfy following equation  
       1 /a+ 1 /b= 1 /f    
       where a is a distance from a start point of the at least one light path to the light condensing member, b is a distance from the light condensing member to an end point of the at least one light path, and f is a focal distance of the light condensing member.  
     
     
         53 . The optical sensor according to  claim 51 , wherein a light diffusing member is provided on the specular reflection light path.  
     
     
         54 . The optical sensor according to  claim 51 , wherein a surface of at least one of the light condensing member and the light diffusing member on a side opposite to the illumination object is a flat surface.  
     
     
         55 . The optical sensor according to  claim 51 , wherein the at least one light emitting unit and the light receiving unit are sealed in a single package.  
     
     
         56 . An optical sensor comprising: 
 at least one light emitting unit that emits a light; and    a light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein    the at least one of the at least one light emitting unit and the first light receiving unit is formed by a surface mounted optical means in which an optical element is surface mounted on a substrate.    
     
     
         57 . The optical sensor according to  claim 56 , wherein the at least one light emitting unit and the light receiving unit are sealed in a single package.  
     
     
         58 . The optical sensor according to  claim 56 , wherein an optical element of the at least one light emitting unit and an optical element of the light receiving unit are mounted on opposite surfaces of same substrate.  
     
     
         59 . The optical sensor according to  claim 56 , wherein 
 both the at least one light emitting unit and the light receiving unit are formed by the surface mounted optical means,    an optical element of the at least one light emitting unit and an optical element of the light receiving unit are surface mounted on a same surface of same substrate, and    a light-shielding means is provided on a virtual line connecting the optical elements.    
     
     
         60 . The optical sensor according to  claim 56 , wherein 
 both the at least one light emitting unit and the first light receiving unit are formed by the surface mounted optical means,    an optical element of the at least one light emitting unit and an optical element of the light receiving unit are surface mounted on a same surface of same substrate, and    a through hole is provided in a surface of the substrate on a virtual line connecting the optical elements.    
     
     
         61 . The optical sensor according to  claim 56 , wherein elements mounted on the surface mounted optical means are laid out not to block a light path.  
     
     
         62 . The optical sensor according to  claim 56 , wherein elements of the surface mounted optical means are surface mounted on the substrate opposite to a light path.  
     
     
         63 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light; and  
 a light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein  
 a sum of the incident angle and the reflection angle is 25 degrees or less.  
   
     
     
         64 . The image formation apparatus according to  claim 63 , wherein a weight average particle diameter of the toner is 8 micrometers or less.  
     
     
         65 . The image formation apparatus according to  claim 63 , wherein an average roundness of the toner is 0.93 or more.  
     
     
         66 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers, toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light; and  
 a light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein  
 a light condensing member is provided on at least one of incident light path along which the light from the light emitting unit travels to the illumination object, a specular reflection light path along which the specular reflection light travels to the light receiving unit, and diffuse reflection light path along which the diffuse reflection light travels to the second light receiving unit.  
   
     
     
         67 . The image formation apparatus according to  claim 66 , wherein a weight average particle diameter of the toner is 8 micrometers or less.  
     
     
         68 . The image formation apparatus according to  claim 66 , wherein an average roundness of the toner is 0.93 or more.  
     
     
         69 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light; and  
 a light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein  
 the at least one of the at least one light emitting unit and the first light receiving unit is formed by a surface mounted optical means in which an optical element is surface mounted on a substrate.  
   
     
     
         70 . The image formation apparatus according to  claim 69 , wherein a weight average particle diameter of the toner is 8 micrometers or less.  
     
     
         71 . The image formation apparatus according to  claim 69 , wherein an average roundness of the toner is 0.93 or more.  
     
     
         72 . An optical sensor comprising: 
 at least one light emitting unit that emits a light; and    at least one light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein    at least one of the at least one light emitting unit and the at least one light receiving unit is surface mounted onto a circuit board, and    a hole forming member that forms a light transmitting hole is provided on a light path between at least one of the at least one light emitting unit and the at least one light receiving unit and the illumination object, a cross section of the light transmitting hole is smaller a cross section of the light path.    
     
     
         73 . The optical sensor according to  claim 72 , wherein, when a diameter of cross section of the light transmitting hole is Rs, a diameter of the cross section of the light path before light passes through the light transmitting hole is Rd, Rs and Rd satisfy the following inequality  
         Rs<Rd− 2  d    
       where d is a margin of error in positioning precision when performing surface mounting onto the circuit board.  
     
     
         74 . The optical sensor according to  claim 72 , wherein optical intensity of the at least one light emitting unit is uniform over entire light emitting surface.  
     
     
         75 . The optical sensor according to  claim 72 , wherein optical sensitivity of the at least one light receiving unit is uniform over entire light receiving surface.  
     
     
         76 . The optical sensor according to  claim 72 , wherein 
 the at least one light emitting unit and the at least one light receiving unit are accommodated in a light-shielding resin case, and    the light transmitting hole is formed on the resin case.    
     
     
         77 . An image formation apparatus comprising: 
 an image carrier having a surface that specularly reflects a light;    a toner image forming unit that forms a toner image on the image carrier;    an optical sensor that detects an amount of toner transfer when the toner image forming unit transfers toner to the image carrier to form the toner image; and    an image density control unit that controls an image density based on a result of detection by the optical sensor, wherein the optical sensor includes 
 at least one light emitting unit that emits a light; and  
 at least one light receiving unit that receives specular reflection light from an illumination object when the light is incident on the illumination object with an incidence angle and specularly reflected with a reflection angle, wherein  
 at least one of the at least one light emitting unit and the at least one light receiving unit is surface mounted onto a circuit board, and  
 a hole forming member that forms a light transmitting hole is provided on a light path between at least one of the at least one light emitting unit and the at least one light receiving unit and the illumination object, a cross section of the light transmitting hole is smaller a cross section of the light path.