Method and apparatus for controlling a light signal in electrophotographic recording apparatus

Abstract

An optical signal control process and circuit providing an improved electronic photography method reproduction apparatus. The reproduction apparatus has a data transmitting unit converting data to be printed to a series of video data in accordance with a first clock signal and transmitting the converted video data in response to a horizontal synchronization signal applied with a predetermined time interval, and a printing control unit for controlling a mechanism used to print the video data by sending electrical signals, providing beam data used to switch the light generation of a light source element controlled by chopped chopping video data applied to the light source element, and generating the horizontal synchronization signal on the basis of a beam detection signal produced by the light source element. A chopping unit is connected between the data transmitting unit and the printing control unit, for chopping the converted video data output from the data transmitting means in response to a second clock signal and for providing the chopped data as the chopping video data. Accordingly, the chopped video data is transmitted as beam data by the printing control unit and is then used to control the amount of light exposed on the photosensitive drum. The amount of the light is controlled optimally by the variable selection of the frequency of the second clock signal.

What is claimed is:  
     
         1 . An electrophotographic developing type reproduction apparatus, comprising: 
 data transmitting means for generating converted data by converting input data to be printed into video data in accordance with a first clock signal, and for transmitting the converted data in response to a horizontal synchronization signal exhibiting a predetermined time interval;    chopping means for providing chopped data by dividing the converted data from said data transmitting means in accordance with a second clock signal; and    printing control means for providing beam data in response to said chopped data, for controlling printing of the video data by generating electrical signals to control generation of a light beam by a light source element, and for generating said horizontal synchronization signal in correspondence with a beam detection signal derived from the light beam by the light source element.    
     
     
         2 . The electrophotographic developing type reproduction apparatus of  claim 1 , further comprised of the second clock signal having a frequency greater than the first clock signal.  
     
     
         3 . The electrophotographic developing type reproduction apparatus of  claim 1 , further comprised of a frequency of the second clock signal being an integer multiple of a frequency of the first clock signal.  
     
     
         4 . The electrophotographic developing type reproduction apparatus of in  claim 1 , further comprised of said chopping means comprising an AND gate having a first input port coupled to receive said converted data and a second input port coupled to received said second clock signal.  
     
     
         5 . The electrophotographic developing type reproduction apparatus of  claim 1 , further comprised of mode selecting means enabling a user to externally change a characteristic of said second clock signal.  
     
     
         6 . The electrophotographic developing type reproduction apparatus of  claim 1 , further comprised of a semiconductor laser device serving as the source element.  
     
     
         7 . The electrophotographic developing type reproduction apparatus of  claim 1 , comprised of: 
 first means for generating a local clock signal; and    second means for generating said second clock signal by dividing said local clock signal in dependence upon a dividing ratio component of said input data.    
     
     
         8 . The electrophotographic developing type reproduction apparatus of  claim 1 , comprised of: 
 means for generating a local clock signal;    first means for generating said first clock signal by dividing said local clock signal; and    second means for generating said second clock signal by dividing said local clock signal in dependence upon a dividing ratio component of said input data.    
     
     
         9 . The electrophotographic developing type reproduction apparatus of  claim 1 , comprised of said chopping means intermittently transmitting said serial video data during pulses of said second clock signal.  
     
     
         10 . The electrophotographic developing type reproduction apparatus of  claim 1 , comprised of: 
 a component of said input data specifying a dividing ratio; and    means for setting a frequency exhibited by said second clock signal in dependence upon said component.    
     
     
         11 . The electrophotographic developing type reproduction apparatus of  claim 1 , comprising: 
 a component of said input data specifying a dividing ratio;    means for setting a frequency exhibited by said second clock signal in dependence upon said component; and    said chopping means dividing said converted data into a series of pulses exhibiting a pulse frequency corresponding to said frequency exhibited by said second clock signal.    
     
     
         12 . A method for controlling a light signal in an electrophotographic developing type reproduction apparatus, said method comprising the steps of: 
 generating converted data by converting input data to be printed into video data, in accordance with a first clock signal, and for transmitting the converted video data in response to a horizontal synchronization signal exhibiting a predetermined time interval;    generating chopped data by dividing the converted data in dependence upon a second clock signal;    supplying beam data for controlling generation of said light signal by a light source element in response to said chopped data; and    generating said horizontal synchronization signal in dependence upon a beam detection signal obtained from said light signal.    
     
     
         13 . The method of  claim 12 , comprising the second clock signal having a frequency higher than the first clock signal.  
     
     
         14 . The method of  claim 12 , comprising a frequency of the second clock signal being an integer multiple of a frequency of the first clock signal.  
     
     
         15 . The method of  claim 12 , comprised of generating the chopped data by applying the converted data to a first input port of an AND gate data and applying the second clock signal to a second input port of the AND gate.  
     
     
         16 . The method of  claim 15 , comprised of changing a characteristic of the second clock signal in response to a selection made by a user of the reproduction apparatus.  
     
     
         18 . An apparatus for printing video data, comprising: 
 data bus means for providing input video data and for providing dividing ratio data;    clock signal generating means for generating a first clock signal and for generating a second clock signal, said second clock signal exhibiting a characteristic depending upon said dividing ratio data;    data transmitting means for converting said input video data into serial video data in response to said first clock signal, and for transmitting said serial video data in response to a horizontal synchronization signal;    logic means for providing chopped video data in dependance upon said serial video data and said second clock signal;    printing control means for generating beam data in response to said chopped video data; and    beam scanning means for providing a laser beam for defining images corresponding to said beam data and for generating a beam detection signal derived from scanning of said laser beam;    said printing control means generating said horizontal synchronizing signal in dependence upon said beam detection signal.    
     
     
         19 . The apparatus of  claim 18 , comprised of generating said first clock signal with a frequency less than said second clock signal.  
     
     
         20 . The apparatus of  claim 18 , comprised of generating said first clock signal with a frequency equal to said second clock signal.  
     
     
         21 . The apparatus of  claim 18 , comprised of said clock signal generating means comprising means for changing said characteristic of said second clock signal in correspondence with changes in said dividing ratio data.  
     
     
         22 . The apparatus of  claim 18 , comprised of said clock signal generating means comprising: 
 first means for generating a local clock signal; and    second means for generating said second clock signal by dividing a frequency of said local clock signal in dependence upon said dividing ratio data.    
     
     
         23 . The apparatus of  claim 18 , comprised of said clock signal generating means comprising: 
 means for generating a local clock signal exhibiting a first plurality of pulses characterized by a local frequency;    first means for generating said first clock signal by dividing pulses of said local clock signal to provide a second plurality of pulses characterized by a second frequency; and    second means for generating said second clock signal by dividing said pulses of said said local clock signal in dependence upon said dividing ratio data, to provide a third plurality of pulses characterized by a third frequency established in dependence upon said dividing ratio data.