Donald John Barclay

Viologen‐based electrochromic light scattering display

In conventional viologen‐based electrochromic displays, contrast changes are achieved by modulating light using the optical absorbance of the electrodeposited film. A display technique is described which uses instead the light scattering properties of the same film to produce intensity variations. Under practical conditions, contrast ratios of 60:1 can be achieved by electrodepositing 1 mC cm−2 of the n‐heptyl viologen cation radical with a 1‐ms current pulse. The display also has memory and is compatible with integrated drive schemes.

Speed considerations for electrochromic displays

The elect rochromic effect based on the reversible electro-deposition of a viologen radical cation has been applied to information display systems. Problems of multiplexing can be overcome by the use of an auxiliary switch, such as a thin-film transistor. The question of speed is the subject of this paper, which discusses the factors influencing the contrast ratio of an electrochromic display. The contrast ratio is determined by electrochemical and optical considerations, the former governing the amount of material deposited and the latter the visual effect of the deposit. Electrochemically, the deposition may be influenced by a variety of mechanisms, including diffusion, migration, electrode kinetics and deposit resistance. Multiple pulse driving gives increased speed in diffusion-limited cases. Optically, the perceived contrast is maximised by increasing the absorbance of the deposited material and by optimising the diffuse reflectance of the display electrode.

Corrosion of Thin-Film Storage Media: A Review

The computer, one of the most important technological innovations of the 20th century, is rapidly decreasing in size while increasing in power. Small, powerful computers require small, high-capacity devices for permanent storage of data. The particulate disk, which has served in generations of computers, is not capable of meeting the projected density requirements and is being replaced by higher capacity thin-film disks and optical disks. The new kinds of disks, however, have less environmental stability than particulate disks. Thus, a stable disk is being replaced by a more vulnerable disk just as computers are being moved from controlled environments into the uncontrolled environments of homes, offices, and plants.