What do TVs count as "no signal"?

I use Samsung "smart" TVs as monitors on several computers. These TVs automatically turn off after a duration of getting "no signal", However, they count a static computer display as "no signal". They turn off unless there is keyboard or mouse activity. Why isn't the computer display treated the same way as the display on a DVD player when it is left displaying a static image? Do DVD players send some sort of "keep alive" signal when displaying static images that computers don't send?

(I haven't found any option on the TVs settings to change this behavior. Perhaps a computer could be programmed to send a mouse movement signal periodically to keep the TV turned on? )

Are you sure you don't have a power saving mode enabled on the computer? Most computer OS now days will turn off the video signal after some amount of inactivity (usually defined as mouse/keyboard input), and this is the default setting - you would need to go in to disable that. So what is happening is you have a static image, the computer gets to some period where it goes into screen saver mode, turns off the video signal to the monitor, monitor sees no video signal so shuts off. You come back, hit mouse/keyboard, OS wakes up the display, and everything is back to normal.
The DVD player is probably just never turning off the video signal. The monitor almost certainly does not care if the video signal is changing - it is just looking that it has a video signal.

They will not display a static image indefinitely because it can eventually affect the screen image. While today's monitors don't get image burn as easily as those in the past, it's still possible.

Now I have a different issue in that my AppleTV source will time out after a certain period of time for certain streaming sources if the display is "turned off".

Why not try a screen saver

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Originally Posted by Mark Wedel

Are you sure you don't have a power saving mode enabled on the computer?

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I'm sure there is a power saving mode involved, but could the computer command the TV to turn off? When the computers are used with dedicated monitors (as opposed to TVs) the monitors may go into a sleep mode, but they don't turn their power off. I don't have to press the power button on the monitor to turn it back on.

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Originally Posted by Jerome Stanek

Why not try a screen saver

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I've run screen savers in the past. Their changing patterns don't keep the TV from turning itself off. By contrast, I've left DVD players playing overnight ( from a list of video files on a USB drive). Without any inputs from the remote, the TV screens were still turned on in the morning. To add more confusion, when I play long Youtube videos on a computer with a dedicated monitor and lie down to watch them, the monitor screen eventually goes blank.

In the days of CRT televisions, leaving a specific image or text on the same place on the face of a monitor, would actually burn the image into the phosphorescent coating on the screen. I first encountered this when working in air traffic control. The monitors used to display current weather conditions at the operating bays would develop this problem over time as text/headings seldom changed while current variables did. The CRTs on the radar scopes would develop the same problem over time for the same reason.

I later experienced the same issues on the CRT monitors used to photograph CT images in multiformat cameras used to expose radiographic film for radiologists to read. While the patient anatomy would change, the graphics/labels remained in the same place and as a result over time, these monitors had to be replaced.

While I haven't experienced it, I supposed the same situation could develop with LED and LCD electronics though I suspect it would take a lot longer to cause the problem when considering the science behind well made electronics of LEDs and LCDs.

Ken, I remember the CRT problem as well having repaired those TVs back in the day. LED/LCD TVs do not have that problem and I've been using them as computer monitors for years. OLED TVs however can have an issue with burn in.

While LCDs don't have much issue with burn in, the newer OLED panels do. This is not much an issue for TV sets, or even if a monitor is used to play games, as those will tend not to changing a bit, but for actual desktop work, things like the windows status bar at the bottom of the screen can get burned in, or over enough time, the fact that you might keep your windows in the same position might not be as directly noticeable as that status bar, but those areas of the screen may end up being a bit dimmer than other parts.

Back to the question - the computer is not likely turning the TV set off, more likely the TV set is turning itself off when it no longer sees a signal after some amount of time. However, I think via the eArc standard (which more or less lets one device sends commands to other devices over HDMI), it may in fact be possible that the computer is telling the TV to turn itself off when it goes into power save mode - I've never looked far into what it can do, but Roku annoyingly added some new feature to their software at some point (which can be disabled but by default was on) which was sending commands to my AV receiver for what input to use. I have a universal remote with codes programmed for that, and roku was messing it up (code used for some other device was seen be roku which then decided it should change the input so the roku was active instead of the other device)