Browse Prior Art Database

AC Plasma Panel With Adjustable Brightness

IP.com Disclosure Number: IPCOM000087225D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Jones, WP: AUTHOR [+2]

Abstract

The subject disclosure relates to an arrangement for automatically adjusting the brightness of an AC gas discharge display panel as required by existing ambient viewing conditions.

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AC Plasma Panel With Adjustable Brightness

The subject disclosure relates to an arrangement for automatically adjusting the brightness of an AC gas discharge display panel as required by existing ambient viewing conditions.

Display panels in certain applications (e.g., exterior located terminals, variable indoor lighting, airplanes, automobiles, etc.) require an automatically adjustable light intensity controlled by the prevailing viewing ambient conditions. In particular, viewing in bright sunlight requires a higher light intensity which, in the case of gas discharge panels, invariably leads to higher power dissipation, higher peak currents and a lower life. Thus, the best strategy is to control the brightness to utilize only the level required by ambient viewing conditions. At present, the only apparent way to achieve variable brightness in AC panels is to utilize the relationship of direct proportionality of light intensity to operating frequency. This method will not increase brightness too much beyond a factor of two from the present panels, since there is appreciable reduction in operating voltage margin associated at high (> 75 KHz) operating frequencies. Of course, the increase in frequency translates into increased power dissipation which has to be handled in the system design.

The present proposal utilizes a different approach of seeding a specially selected dopant in the working gas mixture to supply most of the visible emission. The operating temperature of the panel may now control the brightness of the disp...