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Common Ground Printhead Structures Disclosure Number: IPCOM000050941D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 54K

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Chai, HD: AUTHOR [+3]


A common ground electrode with insulation-isolated print elements optimizes for electrochromic printing.

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Common Ground Printhead Structures

A common ground electrode with insulation-isolated print elements optimizes for electrochromic printing.

This system uses the following: The printhead uses low voltages (less than 20 volts). Its printhead action mechanism is by charge or electron transfer in an ohmic conductive medium through a resistive path to ground. This differs from electrostatic printing. The printhead is surrounded by a highly conductive slectrolyte fluid which acts also as a cooling medium or heat sink through water evaporation.

The print elements (positive or anodes) are unwearable and non-corroding. The condition "unwearable" means that the color-forming reaction does not involve the electrode mass. The condition "non-corroding" is achieved by special films deposited on the print surface, such as noble metal oxides, e.g., RuO(2), or conductive organic polymer films, e.g., conductive polymers of pyrrole.

The elements or print pins at the printhead surface can be connected to the input signals by using various technologies.

Figs. 1A, 1B and 1C show schematically the various structures. There is a common ground 1. The ground can be fashioned from a variety of materials, such as Pt, Au, RuO(2), steel, W or Si. Conductive pins 2 are embedded in the common ground 1 and are surrounded by an insulator 3. The conductive pins are covered either with RuO(2) or an organic conductive film. The insulator can be glass tubing. The salient features are:

- The printing surface is made of a row or more (for staggered

printing) of active positive pins, 4 to 10 mils in diameter

each, and a common ground electrode.

- Each print element is isolated from the rest by an insulating


- The ground electrode is of much larger area than the printing


- The reactions that occur at the prin...