4X20 Vacuum Fluorescent Display FSTN Positive DOT Matrix VFD For Automotive

4X20 Vacuum Fluorescent Display DOT Matrix VFD LCD Module for automative

DISPLAY SPECIFICATION

1. SCOPE
This specification applies to VFD module (Model No: 20S401DA1) manufactured by SSVD (Shanghai Samsung V acuum
Devices)

2. FEATURES
* Both Parallel and Serial Interface: Baud-rate: 300 ~ 19,200 bps, Parity Selectable (non, even, odd)

* Vacuum Fluorescent Display: Self Luminous, High Quality and Readable Display
* Two kinds of CG- ROM Font: ASCII + Japanese and ASCII + European
* +5VDC Single Power Supply: Built in DC/DC Converter
* 4 Brightness Level: 25%, 50%, 75% and 100%
* Character Format: 5*7 Dot Matrix

WHAT'S VFD MODULE

A VFD module incorporates a controller, anode driver, grid driver and power supply circuit to make evaluation easy.

Perform a variety of display control functions using a simple command. Multiple interface options are available.
To accomodate customer specifications, we can do special orders for interface and software.

Introduction

This reference design shows a solution for obtaining the drive voltage required for a vacuum fluorescent display (VFD) power supply in automotive applications. The design includes the complete schematic, and presents the bill of materials (BOM), load/line regulation measurements, and test results.

VFD Basics

A vacuum fluorescent display (VFD) is a type of display used commonly on consumer-electronics equipment such as video cassette recorders, car radios, and microwave ovens. Unlike liquid crystal displays (LCDs), a VFD emits a very bright light with clear contrast and can easily support display elements of various colors. The technology is related to both the cathode ray tube and the nixie tube. Unlike LCDs, however, most VFDs continue to function normally in subzero temperatures, making them ideal for outdoor devices in cold climates.

The VFD is composed of three basic electrodes—the cathode filaments, anodes (phosphor), and grids—under a high-vacuum condition in a glass envelope. The cathode consists of fine tungsten wires, coated by alkaline earth metal oxides which emit electrons. The grids are a thin metal mesh, which controls and diffuses electrons emitted from the cathode. The anodes are conductive electrodes on which the phosphor is printed to indicate characters, icons, or symbols. Electrons emitted from the cathode are accelerated with positive potential applied to both grid and anode; upon collision with the anode the electrons excite the phosphor to emit light. The desired illuminated patterns can be achieved by controlling the positive or negative potentials on each grid and anode. The anode and grid require a DC-regulated voltage to avoid flickering of the display. For driving large VFDs, the cathode requires AC drive to prevent luminance slant, i.e., the difference in brightness from one side of the display to the other. A frequency range of 20kHz to 200kHz is recommended to avoid audible noise and flicker.