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Why do monitors show screen flicker while TVs do not?

Donutoid
By Donutoid
in Displays
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Go to solution Solved by Glenwing,

Ahhh, I see. What types typically don't flicker?

 

Well, for LCD backlights it really depends on the control method, whether or not it's CCFL or LED doesn't matter. The more advanced method is DC control which uses an actual dimming circuit, these types don't flicker at all. The more common method is called PWM, which pulses on and off between 100% and 0% brightness very rapidly, and changes brightness by changing the length of the duty cycle (what percentage of each pulse the light is "ON" for, and how long it is "OFF" for).  For example if it has a 75% duty cycle, then the light is ON for 75% of each cycle and OFF for the other 25%, and it appears to us as 75% brightness since it's only putting out 75% as much light compared to a 100% duty cycle, where it's on for the full duration of each pulse. Basically, PWM flicker gets more noticeable as you turn the brightness down, because the duty cycle shortens, so the "OFF" portion of each cycle gets longer and more noticeable. It also depends on the PWM frequency too, a lot of lower end displays will have something stupid like 180Hz or 240Hz, but some higher-end displays have very high frequency PWM like 10kHz+, which shouldn't result in any perceptible flicker at any brightness level.

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I checked both my computer monitor and TV and noticed that my monitor has a considerable amount of flicker, while my TV doesn't? Why is that?

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differing refresh rates.

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all depends on the monitor 

 

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differing refresh rates.

That's what I thought, but both my tv and monitor run at 60hz which threw me off.

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Depends on the backlight.

Ahhh, I see. What types typically don't flicker?

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Ahhh, I see. What types typically don't flicker?

 

Well, for LCD backlights it really depends on the control method, whether or not it's CCFL or LED doesn't matter. The more advanced method is DC control which uses an actual dimming circuit, these types don't flicker at all. The more common method is called PWM, which pulses on and off between 100% and 0% brightness very rapidly, and changes brightness by changing the length of the duty cycle (what percentage of each pulse the light is "ON" for, and how long it is "OFF" for).  For example if it has a 75% duty cycle, then the light is ON for 75% of each cycle and OFF for the other 25%, and it appears to us as 75% brightness since it's only putting out 75% as much light compared to a 100% duty cycle, where it's on for the full duration of each pulse. Basically, PWM flicker gets more noticeable as you turn the brightness down, because the duty cycle shortens, so the "OFF" portion of each cycle gets longer and more noticeable. It also depends on the PWM frequency too, a lot of lower end displays will have something stupid like 180Hz or 240Hz, but some higher-end displays have very high frequency PWM like 10kHz+, which shouldn't result in any perceptible flicker at any brightness level.

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Well, for LCD backlights it really depends on the control method, whether or not it's CCFL or LED doesn't matter. The more advanced method is DC control which uses an actual dimming circuit, these types don't flicker at all. The more common method is called PWM, which pulses on and off between 100% and 0% brightness very rapidly, and changes brightness by changing the length of the duty cycle (what percentage of each pulse the light is "ON" for, and how long it is "OFF" for).  For example if it has a 75% duty cycle, then the light is ON for 75% of each cycle and OFF for the other 25%, and it appears to us as 75% brightness since it's only putting out 75% as much light compared to a 100% duty cycle, where it's on for the full duration of each pulse. Basically, PWM flicker gets more noticeable as you turn the brightness down, because the duty cycle shortens, so the "OFF" portion of each cycle gets longer and more noticeable. It also depends on the PWM frequency too, a lot of lower end displays will have something stupid like 180Hz or 240Hz, but some higher-end displays have very high frequency PWM like 10kHz+, which shouldn't result in any perceptible flicker at any brightness level.

Turned the brightness on my monitor up all the way and don't notice any at all anymore, not even from my phone's camera. I'll keep that in mind while deciding.

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