Eastman-Kodak Company

Thomas C Weaver

Richard B Wheeler

Thomas L Rockwell

A printer for use in exposing a photosensitive material and method of operation thereof. The printer includes a rotatable polygon mirror having a plurality of adjacent facets. The mirror includes a reference facet and signal generator for generating a polygon index signal which defines a reference position. A light source for directing a light beam is provided for reflection of the beam off each of the adjacent facets for exposing the photosensitive material and defining a writing path. A sensor is also provided for generating a line start signal for each of the facets in response to the light beam passing over the sensor. The printer is provided with a switch for placing printer in a first set-up mode or writing mode. When in set-up mode a counter measures a first time period T.sub.S from the polygon index signal to a first line start signal generated by the reference facet. A counter also measuring a second time period T.sub.LS from a line start signal to the next line start signal generated from the next adjacent facet of the rotatable polygon mirror. A first facet synch signal T.sub.RI is determined using the first time period T.sub.S from said reference facet. T.sub.RI and T.sub.LS are stored in memory. The printer turns on and off the light source in a controlled manner from the information obtained during the set-up mode.

Method and apparatus for controlling operation of a printer

A flash system and method for providing artificial illumination for image capture wherein a source of flash illumination operates selectively in a first mode for projecting light in a first direction toward an indirect reflecting surface to illuminate a subject indirectly and in a second mode for projecting light in a second direction to illuminate the subject directly, electromagnetic radiation reflected directly from the indirect reflecting surface is sensed directly to provide a signal containing information about the indirect reflecting surface, and the information contained in the signal is utilized to control the selective projection of light in the first and second directions to control the quantities of indirect and direct light which illuminate the subject. In one aspect, electromagnetic radiation such as infrared radiation is transmitted to the indirect reflecting surface in a manner such that a portion of the radiation is reflected from the surface back to the flash system where it is detected to provide a signal containing information relating to the distance between the surface and a given location in the flash system. In another aspect, light reflected directly from the indirect reflecting surface during operation of the source in the first or indirect flash mode is received directly by a sensor in the system to provide a signal indicating the presence of the indirect reflecting surface.

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Sodus, NY, United States of America

Thomas C Weaver