Image exposure apparatus

Abstract

An image exposure apparatus of a different angle incident type is provided having a single optical sensor unit for determining the timing for start point synchronization along the main scanning direction, an output level detecting device determining the output level of each beam of light which can be detected by the optical sensor unit, a first modulating device modulating the output level of each beam of light with a pixel data in the light path for exposure, and a second modulating device modulating the output level of each beam of light to a higher level outside of the light path for exposure than the level determined by said output level detecting device.

1 . An image exposure apparatus comprising:
 a group of light sources for emitting at different angles beams of light which are different in the narrow band wavelength from each other;   a deflection optical system for reflecting and deflecting the beams of light received at one reflecting surface in a main scanning direction and scanning in a sequence at predetermined intervals along each scanning line for exposure of a photosensitive material;   a single optical sensor unit located outside of the light path for exposure extending from said deflection optical system to the photosensitive material for providing the timing for start point synchronization of each of the beams of light individually along said main scanning direction;   a sensitivity setting device setting the detection sensitivity of said single optical sensor unit to a higher level than the minimum for detecting each of the beams of light at a reference level;   a first modulating device modulating the output level of each of the beams of light with pixel data along the light path for exposure; and   a second modulating device modulating the output level of each of the beams of light to the reference level outside of the light path for exposure.   
   
   
       2 . The image exposure apparatus according to  claim 1 , wherein said sensitivity setting device is adapted for setting a higher level of sensitivity than the minimum for detecting the reference output level of each of the beams of light when the apparatus is connected to a power supply. 
   
   
       3 . The image exposure apparatus according to  claim 1 , wherein said sensitivity setting device is adapted for setting a higher level of sensitivity than the minimum for detecting the reference output level of each of the beams of light when a photosensitive material is not present across the light path for exposure. 
   
   
       4 . The image exposure apparatus according to  claim 1 , further comprising a self-diagnosing device judging a fault when said single optical sensor unit fails to detect any of the beams of light during the action of at least one of said sensitivity setting device and said second modulating device. 
   
   
       5 . The image exposure apparatus according to  claim 1 , wherein the output level of the beams of light is modified by the action of at least one of an acousto-optic modulating element and an electro-optic modulating element and a magneto-optic modulating element. 
   
   
       6 . The image exposure apparatus according to  claim 1 , wherein the output level of the beams of light is modulated with a driving current supplied to the light sources. 
   
   
       7 . An image exposure apparatus comprising:
 a group of light sources for emitting at different angles beams of light which are different in the narrow band wavelength from each other;   a deflection optical system for reflecting and deflecting the beams of light received at one reflecting surface in a main scanning direction and scanning in a sequence at predetermined intervals along each scanning line for exposure of a photosensitive material;   a single optical sensor unit located outside of the light path for exposure extending from said deflection optical system to the photosensitive material for providing the timing for start point synchronization of each of the beams of light individually along said main scanning direction;   a first modulating device modulating the output level of each of the beams of light with pixel data along the light path for exposure;   a second modulating device modulating the output level of each of the beams of light to a reference level outside of the light path for exposure; and   a sensitivity setting device setting the detection sensitivity of said single optical sensor unit to a higher level than the minimum for detecting the reference output level of each of the beams of light during said operation of the second modulating device.   
   
   
       8 . The image exposure apparatus according to  claim 7 , wherein said sensitivity setting device is adapted for setting a higher level of sensitivity than the minimum for detecting the reference output level of each of the beams of light when the apparatus is connected to a power supply. 
   
   
       9 . The image exposure apparatus according to  claim 7 , wherein said sensitivity setting device is adapted for setting a higher level of sensitivity than the minimum for detecting the reference output level of each of the beams of light when a photosensitive material is not present across the light path for exposure. 
   
   
       10 . The image exposure apparatus according to  claim 7 , further comprising a self-diagnosing device judging a fault when said single optical sensor unit fails to detect any of the beams of light during the action of at least one of said sensitivity setting device and said second modulating device. 
   
   
       11 . The image exposure apparatus according to  claim 7 , wherein the output level of the beams of light is modified by the action of at least one of an acousto-optic modulating element and an electro-optic modulating element and a magneto-optic modulating element. 
   
   
       12 . The image exposure apparatus according to  claim 7 , wherein the output level of the beams of light is modulated with a driving current supplied to the light sources.