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buzzman3200's picture
Last seen: 1 year 2 months ago
Joined: 19/02/2013 - 13:26
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LED backlighting and flicker

Bit of a technical one this, it’s an issue that manufacturers don't appear to acknowledge - at least publically, how to avoid LED flicker?

Which TV is best at minimising backlight flicker?

I have noticed that LED backlit TV's & monitors flicker if not set to the highest brightness setting. It appears that control of the brightness is achieved by switching (pulse width modulation) of the LEDs on and off at a certain frequency. i.e. at the brightest setting the LEDs may be lit continuously, however at the lowest brightness setting the LED's maybe off longer than they are on causing a flickering effect (not noticeable to most).

This effect is most noticeable on predominantly white images e.g. PC applications. This effect can be observed by waving the fingers of a splayed hand or a pen etc. in front of the screen. On the lowest brightness settings you will see a series of stationery fingers at multiple positions (you may have to adjust the speed of movement) silhouetted against the screen, on the maximum brightness setting you will only see blurred movement (no flicker). This may be something that you have not noticed before.

I am susceptible to this type of flicker - over a short period of time it gives me a headache / migraine, so it is of particular importance to me to find a product that does not noticeably flicker (to me).

I am principally interested in a TV but may also use it as a PC monitor.

Does anyone know if some more sophisticated products use a high switching frequency (kHz?) for dimming the LEDs than other products? Also would 3D TV's have a high LED switching frequency to avoid interference with the 3D image? Which products would you recommend to avoid any flickering effect?

I realize that this is quite a technical question and won't be answered by a manufactures technical manual.