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Vacuum Fluorescent Displays (VFD's) have been widely accepted for automotive applications such as electronic instrumentation panels, electronically tuned radios, and information displays because of their self-emissivity, high luminance capability, and high reliability. Color shift capability for VFD's, which is the ability to change color of a given segment, has been discussed as part of the recent automotive display trends towards multi-functional displays with high information content. This paper will report on the VFD color shift system achieved by the use of a Liquid Crystal Color Shutter (LCCS).

In 1976, Vacuum Fluorescent Displays (VFD) were first used for automotive clocks. Through various technical improvements, VFDs have contributed to the advancement of electronic instrument systems for automobiles. At present, VFDs are the most widely used display device for the automotive market. Current applications include message centers, audio systems, temperature control systems, clocks and Head Up Displays (HUD). This paper reports the technical improvements attained and implemented to date. Latest developments are also included.

The Ultra High Luminance Vacuum Fluorescent Display (UHL-VFD) has been brought into practical use for the automotive Head Up Display (HUD) system. To obtain ultra high luminance, the basic characteristics of the UHL-VFD were thoroughly analyzed. This resulted in the utilization of the self standing grid and the optimization of the electrode structure and driving condition. Studies of thermal properties suggest the possibility of a more efficient ultra high luminance display system. Reduction of luminance caused by the thermal quenching of phosphor could be minimized by the use of a heat sink. UHL-VFD's having various colored phosphors were test manufactured and were proven to have sufficient life.

The market demand for Electronically Tuned Radios (ETR) has been for more compact lightweight units at lower cost. At the same time, increased options such as cassette tape and compact disc have continued integration into the system. The Vacuum Fluorescent Display (VFD) technology has maintained pace with the market requirements by increasing the flexibility and usable graphics area within a given mechanically fixed area. Various technological innovations have been made to achieve this, such as the implementation of aluminum thin film circuitry and the elimination of the vacuum exhaust stem. The semiconductor industry has also been keeping pace with the market demand for downsized ETR's. One company, Fujitsu, recently made an announcement of a single chip 4-bit microcomputer. This microcomputer also includes built in Phased Locked Loop (PLL), A/D converter, and VFD drivers in an 80 pin flat package.

A multi-color Vacuum Fluorescent Display (VFD) utilizing an external printed filter has been developed. It features low voltage cathode-luminescence, high brightness, long life and a wide luminous spectrum output. Due to its characteristics, the high efficiency phosphor ZnO:Zn has been used in conjunction with the various printed filters. Fabrication of the filter was achieved using a screen printing technique on the outer flat surface of the VFD. Filter color was controlled by monitoring the amount and ratio of epoxy resin and dyes placed on the VFD surface. Also, the printed filter has been developed as a diffusion mechanism over the VFD for use as a LCD backlight.

Miniature Size Vacuum Fluorescent Displays for Automotive Radio Applications portray the application evolution and the technological advances necessary to develop displays for the automotive products. New VFD technological developments, including thin film and front luminous vacuum fluorescent displays, are outlined. Additionally, FLVFD operational parameters and drive circuitry available in the market are discussed.