Sheet discriminating apparatus and image forming apparatus

Abstract

A sheet discriminating apparatus includes a hardware processor that discriminates characteristics of a sheet. The light emitting element includes a reflective light emitting element and a transmission light emitting element. The sheet discriminating apparatus further includes a reflector that reflects the light when the sheet is not conveyed so that the reflected light enters the light receiving element. The reflective light emitting element includes a first reflective light emitting element that emits light with a first wavelength and a second reflective light emitting element that emits light with a second wavelength. The transmission light emitting element includes a first transmission light emitting element that emits the light with a third wavelength. The reflector is provided in a position that a reflectance of the light emitted by the reflective light emitting element is higher than the reflectance of the light emitted by the transmission light emitting element.

What is claimed is: 
     
         1 . A sheet discriminating apparatus comprising:
 a hardware processor that discriminates characteristics of a sheet by receiving light emitted from a light emitting element to the sheet conveyed along a predetermined conveyor by a light receiving element,   wherein,   the light emitting element includes a reflective light emitting element that causes the light receiving element to receive light reflected off the sheet and a transmission light emitting element that causes the light receiving element provided at an opposing position to receive the light transmitted through the sheet,   the sheet discriminating apparatus further includes a reflector that is provided at a position facing the reflective light emitting element and that reflects the light emitted by the reflective light emitting element when the sheet is not conveyed by the conveyor so that the reflected light enters the light receiving element provided so as to face the reflector,   the reflective light emitting element includes a first reflective light emitting element that emits light with a first wavelength and a second reflective light emitting element that emits light with a second wavelength,   the transmission light emitting element includes a first transmission light emitting element that is provided at a position facing the reflective light emitting element and that emits the light with a third wavelength, and   the reflector is provided in a position that a reflectance of the light emitted by the reflective light emitting element is higher than the reflectance of the light emitted by the transmission light emitting element and transmitted through the sheet.   
     
     
         2 . The sheet discriminating apparatus according to  claim 1 , wherein the first wavelength or the second wavelength is a wavelength within a range from 750 nm to 1100 nm. 
     
     
         3 . The sheet discriminating apparatus according to  claim 1 , wherein,
 the transmission light emitting element includes a second transmission light emitting element that emits the light with a fourth wavelength,   the reflective light emitting element includes a third reflective light emitting element that emits light with a fifth wavelength, and   the first transmission light emitting element, the third reflective light emitting element, the second transmission light emitting element, and the second reflective light emitting element are sequentially irradiated with light from a light having a long wavelength.   
     
     
         4 . The sheet discriminating apparatus according to  claim 3 , wherein the hardware processor discriminates whether the sheet is any one of a plain sheet, a recycled sheet, a coated sheet, and a color sheet. 
     
     
         5 . The sheet discriminating apparatus according to  claim 1 , wherein the reflector is provided in a position that the reflectance of the light emitted from the transmission light emitting element to the sheet and scattered is 20% or less. 
     
     
         6 . The sheet discriminating apparatus according to  claim 1 , wherein the reflector is provided so that the reflectance of the light emitted from the reflective light emitting element is 0.07×(d 0 /d) 2  or more, where d 0  is a distance between the light receiving element and the reflector, and d is a distance between the light receiving element and the sheet as a target to be subjected to a sheet type discrimination processing. 
     
     
         7 . The sheet discriminating apparatus according to  claim 1 , wherein the reflector is provided outside the conveyor. 
     
     
         8 . The sheet discriminating apparatus according to  claim 7 , wherein the reflective member is provided above the reflective light emitting element and the conveyor in an up-down direction. 
     
     
         9 . The sheet discriminating apparatus according to  claim 1 , wherein,
 the conveyance member includes an opening in a range including a portion facing the light emitting element and the light receiving element, and   the sheet discriminating apparatus further includes a transparent protective material that includes translucency in a manner that covers the opening.   
     
     
         10 . The sheet discriminating apparatus according to  claim 9 , wherein the transparent protective material is provided in a manner that covers the opening on the light receiving element side and the reflector side. 
     
     
         11 . An image forming apparatus comprising:
 the sheet discriminating apparatus according to  claim 1 ; and   an image former that forms an image on the sheet.