Futaba Presentation
Futaba Europe GmbH November 2009
VFD Operation Principle
- applied voltage heats up filament which causes thermionic emission
- when positive voltage is applied to grids, electrons are accelerated towards anodes
- when positive voltage is applied to phosphor coated anode, electrons collide with anodes and excite phosphor resulting in light emission
Function of Grids and Anodes
Non Light Emmision
(Grid - & Anode +/-)
Light Emmision
(Grid + & Anode +)
Non Light Emmision
(Grid + & Anode -)
Lead
Getter
ExhaustTip
Grid
GlassSubstrate
ContactLead
AnodeWiring
InsulationLayer
Filament
Anode
VFD Construction
GND
Grid
Ano
de
CLK
LAT
SI
BK
VDD
VH
Filament
VFDDriv
er C
hip
VFD Driver
Base Glass
Filament LeadIC Input LeadFilament Lead
CIG (Chip-in-Glass) VFD Construction
How to drive a Graphic CIG VFD ?
CIG Shift Registor Operation
Driver
Block Diagram
Driver
Timing Chart
Grid Scan Timing
Anode & Grid Construction (e.g. GP1184AI)
Anode & Grid Timing (e.g. GP1184AI)
Grid 1 Grid 2
Anode & Grid Timing Sequence
Grid 1 Grid 2
Anode & Grid Timing Sequence
Grid 3Grid 2
Anode & Grid Timing Sequence
Anode & Grid Timing Sequence (e.g. GP1184AI)
Anode & Grid Timing Sequence
Anode & Grid Timing Sequence
Shift Register Block Diagram
Anode Data (128bit) Grid Data (64 bit)
Shift Register Assignment
Anode Data
Grid Data
Dimming
VFD Power Supply Methods
Power Supply Solution 1: Royer circuit
Advantage: low component cost & high input voltage possible
Disadvantage: custom designed transformer required
Power Supply Solution 2:
For small Displays(high voltage)
LM9022
MC34063
Disadvantage:
higher component cost
& max. 5Vdc input
Advantage:
only standard
components required
Cut-off Bias Requirement (Ek)
Background: Electron Leakage