Eastman-Kodak Company

Jeremy K Chung

Kenneth D Kieffer

Pin S Tschang

Michael William Mattern

A non-impact printhead, for example one that includes a plurality of LEDs, is driven by a current that is programmed to have a linear temperature profile with a desired slope. The change in current with temperature facilitates maintaining of LED uniformity. Linearity between various stages of driver circuitry is maintained by a digital-to-analog converter that includes transistors arranged in a common centroid configuration. Driver current to each LED is provided by a master slave circuit that is dedicated to each LED. Thus, cross-talk between LED channels is minimized.

Non-impact printhead and driver circuit for use therewith

A non-impact printhead for use in recording on a recording medium includes a plurality of energizable recording elements such as LED's. Integrated circuit driver chips are provided that include a current mirror having a master circuit for generating a reference current and a plurality of slave circuits for providing respective driver currents to the recording elements selected for energization. A transistor switch is in series with a respective recording element and switchable from one state to another in response to a signal at its control electrode. An enabling circuit operating upon the control electrode switches the transistor switch to allow current to be selectively provided to the recording element for a predetermined period of time. Each of the slave circuits include an additional slave circuit which provides a current path for facilitating changing of the signal at the control electrode from on voltage level to another such as by allowing a capacitive charge at the control electrode to dissipate. A reference voltage is generated for driving the recording elements. A second transistor in series with the transistor switch establishes a first voltage signal that is input to one electrode of the transistor switch. The first voltage signal varies with variations in the reference voltage. The additional slave circuit generates a voltage signal at the control electrode of the transistor switch means that varies with the reference voltage. Thus, variations in the reference voltage will not substantially affect the level of current driven to the LED's during recording of a pixel.

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Greece, NY, United States of America

Jeremy K Chung