Brightness control circuit for a vacuum fluorescent display
First Claim
1. A circuit for controlling the brightness of a vacuum fluorescent display having filament terminals and connected to anode biasing means, comprising:
- (a) a source of power electrically connected to the filament terminals of the display;
(b) an electronic switch connected between the source and the anode biasing means; and
(c) means for periodically opening and closing the switch, the ratio of time during which the switch is closed to the time during which the switch is open being variable to control the brightness of the display.
0 Assignments
0 Petitions
Accused Products
Abstract
A circuit for controlling the brightness of a vacuum fluorescent display having filament terminals and connected to anode or segment biasing means includes a transformer having a filament winding connected to the filament terminals. The transformer is driven by a 60-cycle power source. An electronic switch, including a transistor, is connected between a center tap of the filament and the anode biasing means (at a common ground) and circuit means open and close the switch at a 60-cycle rate. The ratio of time during which the switch is closed to the time during which the switch is open is variable to control the brightness of the display.
-
Citations
10 Claims
-
1. A circuit for controlling the brightness of a vacuum fluorescent display having filament terminals and connected to anode biasing means, comprising:
-
(a) a source of power electrically connected to the filament terminals of the display; (b) an electronic switch connected between the source and the anode biasing means; and (c) means for periodically opening and closing the switch, the ratio of time during which the switch is closed to the time during which the switch is open being variable to control the brightness of the display. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
Specification