High resolution halftone dot generator system including LED array

A dot generator system for a color scanner including means for providing a picture value for use in exposing a halftone separation comprising:

• an LED microchip array having multiple staggered rows of LED's, said LED microchip array being mounted opposite to and imaged upon the exposure surface of a color scanner, said LED microchip array being movable in a two dimensional coordinate system relative to said exposure surface;
• an addressable stored dot density profile array, said dot density profile array having a microdot density value stored at each memory address;
• bit slice means for determining a dot density profile array address value and recalling the corresponding microdot density value;
• compare logic means for comparing said recalled microdot density value with a picture value to determine whether an LED on said LED array will be activated, said compare logic means transmitting an exposure data bit indicating whether the corresponding LED is to be activated;
• serial to parallel converter means for receiving said exposure data bits from said compare logic means and accumulating said bits to construct an exposure data word equal in length to the number of active LED's on said LED array;
• stagger compensation logic means for receiving said exposure data word from said serial to parallel converter means, said stagger compensation means introducing delay timing to data bits corresponding to at least some of said staggered LED rows, said delay timing being equal to the time required for said LED microchip array to traverse the distance on said exposure surface between each staggered row and the first row;
• output buffer means for receiving a modified exposure data word from said stagger compensation means and transmitting said modified exposure data word to said LED array;
• and
• clock generator means for providing a timing reference for said delay timing and transmittal of said modified exposure data word from said output buffer to said LED array, said clock generator means also providing a stroke pulse to said LED array and a picture value request pulse for signaling the color scanner that the dot generator system is ready to receive the next picture value.