Sheet feeder with a light sensor

Abstract

A sheet feeder includes a housing, a cover and a sensing device. The cover is mounted on the housing, and the sensing device is disposed between the housing and the cover. The sensing device includes a light sensor and a reflecting mirror. The light sensor is mounted on the inside surface of the cover, and the reflecting mirror is mounted on the housing opposite the light sensor. As a signal light is being emitted from the light-emitting unit of the light sensor, the signal light is reflected from the reflecting mirror or a document and received by the receiving unit of the light sensor. The reflected signal light will then be transformed to a signal voltage which, according to its value, indicates the using status of the sheet feeder, such as ‘without document’, ‘document present’ or ‘cover open’, such that the number of the sensors on the sheet feeder can be reduced and the manufacturing costs can be lessened.

1 . A sheet feeder with a light sensor to be mounted on an image scanning device which provides an automatic feeding function for a to-be-scanned document comprises: 
 A housing;    A cover mounted on said housing and opened or closed against said housing;    A feeding passage formed between said cover and housing for the to-be-scanned document;    A sensing device mounted between said housing and cover;    Said sensing device comprising a light sensor and a reflecting mirror opposite to said light sensor; said light sensor receiving signal lights of different intensities under different circumstances, such as when no said to-be-scanned document is fed, when said to-be-scanned document is fed, and when said cover is open; said signal lights of the different intensities being then transformed to different voltage values and said voltage value serving as an indication of the operational status of said sheet feeder.    
   
   
       2 . The sheet feeder of  claim 1 , wherein said light sensor of said sensing device and said reflecting mirror are opposite to each other and form a non-parallel configuration.  
   
   
       3 . The sheet feeder of  claim 1 , wherein said light sensor has a light-emitting unit and a receiving unit.  
   
   
       4 . The sheet feeder of  claim 3 , wherein said light-emitting unit and said receiving unit are mounted on an inside surface of said cover.  
   
   
       5 . The sheet feeder of  claim 3 , wherein said light-emitting unit and said receiving unit are mounted on said housing.  
   
   
       6 . The sheet feeder of  claim 1 , wherein said image scanning device is a sheet-feeding scanner.  
   
   
       7 . The sheet feeder of  claim 1 , wherein said image scanning device is a flatbed scanner.  
   
   
       8 . The sheet feeder of  claim 1 , wherein the voltage value is defined as V 1  when no said to-be-scanned document is fed, the voltage value is defined as V 2  when said to-be-scanned document is fed, and the voltage value is defined as V 3  when said cover is open, and V 1 >V 2 >V 3 .