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New Nebulizer Electrode System for Electrochromic Printing

IP.com Disclosure Number: IPCOM000051884D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 4 page(s) / 62K

Publishing Venue

IBM

Related People

Mitchell, JW: AUTHOR [+3]

Abstract

Attempts have been made to adapt commercial nebulizers for use in electrochromic printing; however they have serious shortcomings. Commercial nebulizers are too bulky, and they require considerable power because they do not affect a thin layer of solution but rather the bulk of the liquid to be nebulized. Besides, they would require a carrier gas to lead the mist over the paper. Finally, they have a rather low wetting capacity and are expensive.

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New Nebulizer Electrode System for Electrochromic Printing

Attempts have been made to adapt commercial nebulizers for use in electrochromic printing; however they have serious shortcomings. Commercial nebulizers are too bulky, and they require considerable power because they do not affect a thin layer of solution but rather the bulk of the liquid to be nebulized. Besides, they would require a carrier gas to lead the mist over the paper. Finally, they have a rather low wetting capacity and are expensive.

This article describes the combination of an ultrasonically vibrated piston and a printhead moving with it, to achieve paper activation and electrochemical printing.

Fig. 1 shows a diagram of the printing device supported in the printhead carrier. The system consists of two basic parts: (a) the electrodes (printhead) and (b) the atomizer.

The former usually consists of an array of electrodes (Fig. 1A) which may assume different configurations and be of different materials, depending on the type of printing to be achieved and the nature of the electrochromic solution. For example, the electrodes could be made of wearable stylii whose mass would be transferred into the paper as a consequence of the printing process. Or they could be unwearable stylii, such as platinum or stainless-steel. The printhead (Fig. 1B) advances along the paper behind the atomizer and, as the electrodes are pulsed against a reference electrode, they print a mark on the thin layer of the paper wetted by the mist. The reference electrode is on the same side of the paper, as shown in Fig. 1A.

The nebulizer is based on the following principle: When a fluid film is spread over the surface of a piston (S in Fig. 1A) that is ultrasonically vibrated, the oscillating vibration at the surface causes the fluid film to break-off into tiny droplets. The theoretical expression for the wavelength of the vibrations was derived by Kelvin as: lambda = (2 pi alpha/rho f/2/)/1/3/ (1) where alpha is the surface tension, rho is the specific gravity of the fluid, and f is the driving frequency in hertz. It turns out that the mist drop diameter is proportional to: d = k lambda (2) So that: d/3/ = K /2 eta/ alpha over rho f/2/ (3) From the above expressions and considering a flui...