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Driving Method for Multi-Stylus Electrostatic Printhead

IP.com Disclosure Number: IPCOM000042391D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Toyokawa, K: AUTHOR

Abstract

An electrostatic printhead comprised of a one-dimensional array of stylus electrodes and plate electrodes is usually driven by a time-multiplexed method where only a small part of the stylus and plate electrodes are selected at any instant for the sake of decreasing the number of driven transistors and wire connections. The time-multiplexed driving method, however, has a drawback in that printed images have nonuniform densities between the edge and the middle areas in the block of electrodes selected at an instance. This nonuniformity comes from an edge effect that a stronger electric field is induced at the edge rather than at the middle. A new driving method and circuit eliminates the edge effect, and improves the print quality in the electrostatic printer.

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Driving Method for Multi-Stylus Electrostatic Printhead

An electrostatic printhead comprised of a one-dimensional array of stylus electrodes and plate electrodes is usually driven by a time-multiplexed method where only a small part of the stylus and plate electrodes are selected at any instant for the sake of decreasing the number of driven transistors and wire connections. The time-multiplexed driving method, however, has a drawback in that printed images have nonuniform densities between the edge and the middle areas in the block of electrodes selected at an instance. This nonuniformity comes from an edge effect that a stronger electric field is induced at the edge rather than at the middle. A new driving method and circuit eliminates the edge effect, and improves the print quality in the electrostatic printer. This method is based upon the time-multiplexed selection of stylus within block A or B (Fig. 1). When a block A is selected, the stylii are turned on in two steps, namely the odd numbered stylii of block A (1, 3, 5,....,) are turned on at the first step, and then the even numbered stylii (2, 4, 6,...,) are turned on in the second step. The new driving method can eliminate the edge effect even when all block image data are given, as shown in Fig. 2. An example of new stylus driver circuit is shown in Fig. 3. The improvement of the driving circuit is as follows: 1. The counters of data sample pulses consist of three parts. The modulo (m/2) and modulo 2 co...