History
In the past, most adjustments on TV sets were performed with analog controls such as potentiometers and switches. This is still used in modern monochrome portable TVs. After remote controls were invented, digital adjustments became common. They needed an external display, which was LED, LCD, or VFD based. Including this display increased manufacturing costs.
When electronics became more advanced, it became clear that adding some extra devices for an OSD was cheaper than adding a second display device. TV screens had become much bigger and could display much more information than a small second display. OSDs display graphical information superimposed over the picture, which is done by synchronizing the reading from OSD video memory with the TV signal.
On-screen displays first began to appear in the 1980s on TVs. By the mid-1990s, VCRs with these displays became widely available. This made it possible to reduce the size (and cost) of the VFDs used in VCRs. Akai have been credited with the introduction of OSD in VCRs in the 1980s, including the introduction of on screen programming. All DVD players also use on-screen displays. Many PAL television sets use the internal Teletext decoder's graphics rendering system to further reduce costs.
More recently (as of about 2005), the decline in CRT-based TV sets and rise in LCD/plasma televisions has seen the use and availability of dedicated OSD devices decline, as it is more cost effective to integrate OSD functions inside the main graphics processor. Modern LCD television monitors usually incorporate only two or three integrated circuits. Examples of integrated circuits to perform dedicated OSD are MAX7456 and STV5730. Both operate with NTSC or PAL, mixing with an existing signal or self-generating. Both have slightly different capabilities. This can be done by PIC video superimposer too.
Read more about this topic: On-screen Display
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