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Brightness Control Modulation in a Plasma Panel

IP.com Disclosure Number: IPCOM000042684D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hoffman, HS: AUTHOR [+2]

Abstract

When the number of lighted pels (picture elements) in a plasma panel causes the discharge current drawn by the circuitry to reach an unacceptable level, the level must be reduced. A means for reducing the discharge current to acceptable levels is described below. A high current warning signal, generated, for example, by monitoring the amplitude of the discharge current, is used to override the brightness control (repetition rate setting) of the display for a relatively short interval. If the required number of "on" pels are not turned "off" during this interval, the warning signal will again be sensed and the sequence repeated. The resulting oscillation will modulate the brightness setting to provide a display intensity approximately midway between the normal brightness and the minimum brightness, i.e.

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Brightness Control Modulation in a Plasma Panel

When the number of lighted pels (picture elements) in a plasma panel causes the discharge current drawn by the circuitry to reach an unacceptable level, the level must be reduced. A means for reducing the discharge current to acceptable levels is described below. A high current warning signal, generated, for example, by monitoring the amplitude of the discharge current, is used to override the brightness control (repetition rate setting) of the display for a relatively short interval. If the required number of "on" pels are not turned "off" during this interval, the warning signal will again be sensed and the sequence repeated. The resulting oscillation will modulate the brightness setting to provide a display intensity approximately midway between the normal brightness and the minimum brightness, i.e., the minimum repetition rate set by the override. The sudden initial drop to this modulated brightness will be immediately apparent, thereby directing the operator's attention to the high pel count situation. On erasing pels, the transition to normal brightness will be similarly sudden; the brightness adjustment will still provide adjustment, but at a lower intensity level. Alternatively, the return to normal intensity can occur after a predetermined delay, thereby increasing the proportion of the time at the lowest brightness level and providing a minimum brightness condition until some of the "on" pels are turned "o...