Vacuum Fluorescent (VFD)

‌1. Vacuum Fluorescent Display Overview‌

VFD (vacuum fluorescent display module) is a self-luminous display device based on the principle of vacuum electron tubes, which realizes multicolor light emission by electron bombardment of phosphors. Its core structure includes filament (cathode), grid, anode, and fluorescent coating, supporting various display forms such as numbers, characters, patterns, etc.‌

 

‌2. What are the Technical Characteristics of Vacuum Fluorescent Display?‌

‌Brightness and Lifespan‌: high brightness (usually more than 2000 cd/m²), long lifespan (about 10,000 to 30,000 hours)‌;

 

‌Drive Voltage‌: low drive voltage (DC or pulse drive), typical operating voltage is 5V-50V‌;

 

‌Multi-color Display‌: mainly blue-green in the early days, now it can support multiple colors such as red, orange, and yellow‌;

 

‌Environmental Adaptability‌: wide operating temperature range (-40 °C to 85 °C is common), suitable for industrial scenarios‌.

 

‌3. Where is Vacuum Fluorescent Display Used?‌

‌Consumer Electronics‌: volume indicator on audio panel, status display of home appliances‌;

 

‌Industrial Equipment‌: instrument data visualization, interactive interface of automation equipment‌;

 

‌In-vehicle System‌: car dashboard, central control information screen‌.

 

‌4. Modular Design of Vacuum Fluorescent Display‌

‌Interface Type‌: support parallel, serial (such as SPI/I²C) and custom protocol interface‌;

 

‌Package Form‌: standard size module (such as D0103MT-20-0110N) or customized package, thickness is usually ≤15 mm‌;

 

‌Drive Solution‌: commonly used PT6311/PT6312 and other dedicated driver ICs, need to cooperate with the oscillation circuit to realize filament AC power supply‌.

 

‌5. Supply Chain and Selection for Vacuum Fluorescent Display‌

‌Core Manufacturers‌: Noritake, Matrix Orbital, Panasonic, and other manufacturers provide commercial modules‌;

 

‌Selection Parameters‌: need to pay attention to indicators such as character size (such as 5×7 dot matrix), observation area, RoHS compliance, etc.

 

6. VFD FAQs

1) What is the working principle of VFD? ‌

VFD releases electrons by heating the filament. Under the acceleration of the electric field of the gate and the anode, the electrons hit the phosphor on the anode to stimulate light emission. The filament is usually powered by AC to avoid the problem of uneven brightness caused by DC. The anode needs to apply a voltage higher than the filament potential to achieve effective light emission.

2) How to detect common faults of VFD? ‌

‌Filament detection‌: Use a multimeter to measure the filament resistance. The normal resistance value is very small. If it is infinite, it means that the filament or pin is an open circuit. ‌

‌Gas leakage detection‌: If there is no faint red light after the filament is powered on, and it cannot work, it may be due to a rupture in the vacuum chamber. ‌

‌Display abnormality‌: Check whether the gate and anode voltages are normal and whether the phosphor is aged.

3) What technical details should be paid attention to when driving the VFD module? ‌

‌Power supply mode‌: AC power supply is recommended for the filament to avoid uneven brightness, and the grid and anode need independent boost circuits (such as 21V negative voltage)‌;

‌Cut-off bias voltage‌: used to eliminate “ghosting”, usually obtained by dividing the grid voltage through a voltage stabilizing circuit‌;

‌Control circuit design‌: It is necessary to cooperate with the driver chip (such as 74HC595D) and the isolated power supply module to achieve stable control‌.

 

4) What should I do if the display is blurred or the brightness is uneven during the use of the VFD? ‌

‌Blur problem‌: Check whether the anode voltage is stable, whether the phosphor is damaged, or whether there is a quality problem with the filter‌;

‌Uneven brightness‌: Confirm whether the filament is powered by AC, and check whether the grid voltage distribution is uniform‌;

‌Environmental interference‌: Avoid direct strong light and ensure that the use environment meets the dark or low light requirements‌.‌