A nixie tube, also known as a glow tube, is an electronic device that displays digital and other information. The glass tube consists of an anode and a plurality of cathodes made of wire mesh. Most nixie cathodes are in the shape of numbers. The tube is filled with a low-pressure gas, usually mostly neon with some mercury and/or argon. When one cathode is charged, the nixie tube emits a colored light, usually orange or green, depending on the gas inside.
The most common form of nixie has 10 cathodes in the shape of the numbers 0 through 9, and some nixies have one or two decimal points. However, there are other types of digital tubes that display letters, marks, and symbols. For example, the cathode of a “digitizer” is a mask made of a template with holes in the shape of a number.
A DC voltage of 170 volts is applied between the cathode and the anode, and each cathode emits the red-orange glow of neon. Different types of nixie tubes have different colors due to different gas mixtures. Long-lived digitizing tubes are manufactured with mercury, which reduces sputtering, and the resulting light is in a blue or purple tone. In some cases, these colors are filtered by a red or orange filter coating on the glass.
Embedded development common module: Nixie tube principle and application
How do digital tubes form the numbers 0 to 9?
Digital tube, also known as 8 LED lights, is composed of 8 LED lights.
In our practical application, these 8 LED lights are named as a, b, c, d, e, f, g, h (or dp).
The inside of the digital tube, according to the different connections, the digital tube is divided into a common negative digital tube and a common positive digital tube.
Common positive digital tube: 8 LED lamp anodes all connected together, the cathode of each LED lamp respectively out;
Common negative digital tube: the cathode of 8 LED lights are all connected together, and the anode of each LED lamp is respectively drawn out;
The internal structure of the common negative digital tube is shown on the left and the internal structure of the common negative digital tube is shown on the right.
The common end of the digital tube is connected to a high level, and one end is connected to a low level, and the section is bright; The common negative digital tube is connected to a low level at a common end, and a high level at one end, and the segment is bright. The logic of the two is just the opposite.
Drive display of Nixie tube
Generally speaking, for the digital tube normal display, it is necessary to use the driving circuit to drive the digital tube each section code, so as to show the number we want, so according the different driving ways of the digital tube, can be divided into static and dynamic two types.
1. Static display driver
The static drive is also known as the DC drive. Static drive refers to each digit tube each segment code is driven by a single chip microcomputer I/O port, or use such as BCD code two-decimal decoder decoding to drive. The static driver has the advantage of simple programming and high display brightness, the disadvantage is to occupy I/O ports, such as the drive 5 digital tube static display needs 5×8 = 40 root I/O ports to drive, to know that an 89S51 microcontroller available I/O ports only 32, the practical application must increase the decoding driver to drive, increase the complexity of the hardware circuit.
2. Dynamic display driver
The dynamic display interface of the digital tube is one of the most widely used display modes in single-chip microcomputers. The dynamic drive is to connect the names same end of all 8 display strokes of the digital tube “a, b, c, d, e, f, g, dp” together. In addition, a bit gate control circuit is added to the common pole COM of each digital tube, and the bit gate is controlled by their independent I/O line. When the single chip microcomputer output glyph code, all the digital tubes will receive the same glyph code, but which digital tube will show the glyph, depends on the single chip microcomputer control of the bit gate COM terminal circuit, so as long as we need to display the gating control of the digital tube, the bit will show the glyph, no gating of the digital tube will not be bright. By taking turns to control the COM end of each digital tube, each digital tube in turn controlled the display, this is a dynamic drive. In the process of rotating the display, each nixie tube is lit for 1 ~ 2ms. Due to the phenomenon of human visual retention and the afterglow effect of LED, although in fact each nixie tube is not lit at the same time, as long as the scanning speed is fast enough, people will be given the impression of a set of stable display data without flickering. The effect of dynamic display is the same as that of the static display. Can save a lot of I/O ports, and lower power consumption.
Embedded development common module: Nixie tube principle and application