Vacuum fluorescent display driver
First Claim
1. A vacuum fluorescent display driver for driving a vacuum display device having a filament, a grid, and at least one illuminatable segment, comprising:
- a segment selecting circuit which selectively applies an electrical potential of a particular polarity to a segment to illuminate that segment;
a grid driver circuit which applies an electrical potential of said particular polarity to the grid in order to illuminate the device; and
a filament supply which supplies an electrical current to the filament during a first portion of a duty cycle in order to heat the filament and applies an electrical potential opposite said particular polarity to the filament during a second portion of the duty cycle in order to produce an electrical potential between the filament, the grid, and any segment to which said electrical potential of particular polarity is applied sufficient to light the selected segment.
1 Assignment
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Accused Products
Abstract
A vacuum fluorescent display driver and method for driving a vacuum display device includes a segment selecting circuit which selectively applies a potential of a particular polarity to a segment to illuminate that segment and a grid driver circuit which applies a potential of that polarity to the grid in order to illuminate the device. A filament supply supplies a current to the filament during a first portion of a duty cycle in order to heat the filament and applies a potential of polarity opposite to that applied to the filament during a second portion of the duty cycle in order to produce a potential between the filament, the grid, and any segment which is selected sufficient to illuminate the selected segments. The driver is especially adapted for use with a microcomputer particularly in a vehicle display mirror, such as a compass mirror.
41 Citations
58 Claims
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1. A vacuum fluorescent display driver for driving a vacuum display device having a filament, a grid, and at least one illuminatable segment, comprising:
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a segment selecting circuit which selectively applies an electrical potential of a particular polarity to a segment to illuminate that segment; a grid driver circuit which applies an electrical potential of said particular polarity to the grid in order to illuminate the device; and a filament supply which supplies an electrical current to the filament during a first portion of a duty cycle in order to heat the filament and applies an electrical potential opposite said particular polarity to the filament during a second portion of the duty cycle in order to produce an electrical potential between the filament, the grid, and any segment to which said electrical potential of particular polarity is applied sufficient to light the selected segment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A vacuum fluorescent display circuit, comprising:
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a vacuum fluorescent display device having a filament, a grid and a plurality of display segments; a microcomputer operable from a power supply of a particular polarity, said microcomputer having output ports connected with said segments and selectively activated by said microcomputer to illuminate particular segments of said display device, said microcomputer having an output port connected with said grid and selectively activated by said microcomputer to illuminate the display; and a filament supply circuit operated from said particular polarity under the control of said microcomputer for heating said filament and for driving said filament in an opposite polarity in order to produce an electrical potential between said filament and said grid sufficient to illuminate the activated segments. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A display mirror system for a vehicle having a positive voltage electrical supply system, comprising:
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a reflective element having a reflective surface, a housing for said reflective element and a vacuum fluorescent display device in said housing for displaying information, said vacuum fluorescent display device having a filament, a grid and a plurality of display segments; a microcomputer having at least one input port for receiving information to be displayed and output ports connected with said segments and selectively activated by said microcomputer to illuminate particular segments of said display device, said microcomputer having an output port connected with said grid and selectively activated by said microcomputer to illuminate the display; and a filament supply circuit under the control of said microcomputer for heating said filament and for driving said filament to an electrical potential of negative polarity in order to produce an electrical potential between said filament, said grid, and activated segments sufficient to illuminate the activated segments. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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50. A method of operating a vacuum display device from a unipolar electrical source, the vacuum display device having a filament, a grid, and a plurality of illuminatable segments, including:
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applying an electrical potential from the source to those segments which are to be illuminated; applying an electrical potential from the source to the grid if the display is to be on; applying an electrical current from the source to the filament during a minor portion of the duty cycle in order to heat the filament; and applying an electrical potential having a polarity opposite to the polarity of the source during a major portion of the duty cycle in order to produce an electrical potential between the filament, the grid, and those segments which are to be illuminated. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58)
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Specification