Bar graph display

A bar graph display is a display method by means of scale for the size of a signal, the length of a (often vivid) beam (in the English bar for bar) varies with the signal magnitude. Equivalent German terms are bar display and band display .

Scale display with a band of 51 light segments

Tube radios and older amplifiers and tape recorders already had such displays for the signal strength (“ magic eye ”) realized with tuning indicator tubes . Today, digital measuring devices (such as digital multimeters ) are often equipped with a bar graph display in addition to the numeric display, in order to be able to recognize signal changes or maxima more quickly. These are often implemented as LCD segments in the display and are controlled more quickly than the numeric display, and a change can be observed more clearly. In electronic spirit levels or pipe locators (in addition to acoustic signals), geometric bar diagrams also show geometric relationships.

Built-in measuring device with LCD reflective + transmissive (with H.)

To monitor industrial processes, built-in measuring devices with a vertical display surface are used in so-called control rooms. In the example shown from the 1970s, the right side shows the upper and lower limit values as well as the target value of a measured variable, while the left side shows the current measured value as a bar. With ambient light in such control rooms, purely reflective TN LC displays (LCDs) like the illustration on the left are rather difficult to read. Therefore, an arrangement was developed with a fluorescent tube (cold cathode tube of the CCFL type) as a light source and a diffuser as a light distributor for backlighting a TN-LCD in transmitted light, which can be seen on the right-hand side of the figure and was easy to read.

Mixers are often one of a LED existing -line bargraph level meter, the upper LEDs for warning of overload red.

Fluorescent displays in home hi-fi devices often have bar graph displays for the NF level, which consist of a large number of light segments.

Bar graph displays are also used in software that can be operated graphically for measurement purposes and in audio processing as an instrument for level display.
As a progress indicator , they often show the progress of a storage, installation or download process on the computer.