1 August 1990 High-resolution LED printhead with uniformity compensation
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This paper describes the implementation and performance of high speed light-emitting-diode (LED) printheads. The printhead is essentially a line of LED''s the width of a page and is used for printing on ordinary paper using the electro-photographic process. The printhead design approach adopted by Optotek uses a modular construction with 256 bits per module and a resolution of 300 DPI allowing construction of different sizes using a common building block. The unique design allows uniformity compensation through pulse width modulation of LED drive currents giving nearly equal energy outputs for all pixels. Since the intensity is measured after the printhead has been completely assembled the measurements incorporate variations in drivers LED''s and optics. the intensity measurements are used to burn on board compensation EPROMS providing 4 bits of uniformity compensation for each pixel. A common control for average intensity adjustment is included. Units of various lengths have been provided to a number of printer manufacturers in North America Europe and Japan. A 6144 element printhead is presently in production. This unit operates at a peak LED emission wavelength of 667nm and provides a pixel power of 2. 5 through self focusing fiber optics. A separate serial digital interface for each module allows an effective bitrate of 200 MHz for this unit. The modular design permits implementation of higher resolutions. LED emission wavelength can be tailored to match spectral sensitivity of photoreceptors.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
P. Gunnar Wareberg, Brian Baumgartner, Steve E. Wilson, "High-resolution LED printhead with uniformity compensation", Proc. SPIE 1254, Optical Hard Copy and Printing Systems, (1 August 1990); doi: 10.1117/12.19858; https://doi.org/10.1117/12.19858


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