Performance

Flicker

Flicker in LED displays is visible pulsing or blinking that occurs when refresh rate is too low or interacts poorly with ambient lighting or camera sensors. Professional LED walls use high refresh rates (3840Hz+) and PWM frequencies to eliminate perceptible flicker for both human viewers and cameras.

Understanding Flicker

Flicker is a critical quality metric for LED displays. Understanding its causes enables proper panel selection and configuration for flicker-free operation.

Causes of Flicker

**Refresh Rate:** The rate at which the entire image is redrawn. Low refresh rates cause visible pulsing.

**Scan Ratio:** Multiplexed displays scan portions of the image sequentially. Lower scan ratios can cause visible flicker.

**PWM Brightness Control:** LEDs controlled by on/off pulsing can flicker at low brightness if PWM frequency is insufficient.

Perceptibility Thresholds

**Human Vision:**

  • Central vision: ~60-90Hz
  • Peripheral vision: Up to 100Hz+ sensitivity
  • Individual variation exists

**Camera Capture:**

  • Depends on frame rate and shutter
  • Visible with most shutters below ~1000Hz panel refresh
  • Higher panel refresh reduces camera flicker

Flicker-Free Specifications

**For Human Viewing:**

  • 1920Hz minimum
  • 3840Hz recommended
  • Virtually invisible

**For Camera:**

  • 3840Hz minimum
  • 7680Hz+ recommended for VP
  • Combined with genlock for best results

Flicker Testing

**Visual:** Wave hand in front of display—stroboscopic effect indicates visible flicker.

**Camera Test:** Record at various shutter speeds—bands indicate camera-visible flicker.

**Specialized Equipment:** Flicker meters measure flicker percentage and frequency.

Reducing Flicker

**Panel Selection:** Choose panels with high refresh rate and PWM frequency.

**Brightness Settings:** Some panels flicker more at low brightness—test at actual operating levels.

**Driver IC Quality:** Better driver ICs maintain flicker-free operation across brightness range.

Environment Interaction

**Artificial Lighting:** LED panels can interact with other PWM-driven lights (stage LEDs, fluorescents) creating beat frequencies.

**Camera Interaction:** Camera shutter and panel refresh must be considered together.

Application Requirements

**Broadcast/IMAG:**

  • 3840Hz minimum
  • Genlock recommended
  • Test with actual cameras

**Virtual Production:**

  • 7680Hz+ preferred
  • Genlock required
  • Camera sync essential

**General Events:**

  • 1920Hz acceptable for human viewing
  • Higher for broadcast capture

Frequently Asked Questions

Why do some LED walls flicker on camera?

Camera sensors capture individual frames that may catch the LED mid-refresh cycle, appearing as flicker or brightness variation. This is most visible with low refresh rates (<1920Hz) or when camera shutter speed does not align with LED refresh. Higher refresh rates (3840Hz+) minimize this effect.

Can human eyes see LED flicker?

Most people cannot perceive flicker above 60-90Hz in central vision, but peripheral vision is more sensitive. Low refresh rates, certain brightness levels, or interaction with ambient lighting can cause perceptible flicker. Sensitive individuals may notice flicker that others miss.

How does PWM cause flicker?

PWM (Pulse Width Modulation) controls LED brightness by rapidly turning LEDs on and off. If the PWM frequency is too low, flickering occurs—especially at lower brightness settings where the off-time is longer. Higher PWM frequencies and better driver ICs reduce this.

Related Terms

Refresh Rate

Performance

Refresh rate measures how many times per second an LED display updates its image, expressed in Hertz...

Scan Ratio

Processing

Scan ratio describes the LED driving method that determines how many pixel rows illuminate simultane...

Moiré Pattern

Performance

Moiré patterns are wavy, rainbow-colored interference patterns that appear when cameras capture LED ...

PWM (Pulse Width Modulation)

Processing

PWM is the technique used to control LED brightness by rapidly switching LEDs on and off. The ratio ...

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