For AV integrators specifying premium displays, refresh rate is a critical metric—but its mechanics in LED technology differ significantly from LCD or OLED. In an LED display, the refresh rate represents the exact number of times an individual LED chip cycles completely on and off per second.

While the industry has standardized around high refresh rates, achieving these numbers requires balancing driver hardware costs against grayscale performance.

 

The mechanics: scan lines vs. hardware costs

Unlike other display types, the LEDs on a matrix do not illuminate simultaneously; they light up sequentially, row by row.

• The scanning constraint: Reducing the scan number on the display hardware inherently increases the refresh rate, boosts grayscale depth, and minimizes coupling artifacts.

• The cost trade-off: Reducing the scan rate requires a significantly higher volume of driver ICs (integrated circuits). This sharp increase in component density drives up manufacturing costs, meaning integrators must balance budget against performance targets based on the application.

 

The silicon solution: sub-period modulation

To avoid cost-prohibitive hardware designs, modern chip manufacturers use PWM (pulse-width modulation) to divide a single frame's total lighting time into multiple sub-period intervals.

• Grayscale calculations: For a 13-bit LED screen, there are 8,192 levels of brightness. If multiplied straight across by a standard 60Hz frame rate, the refresh rate would skyrocket past efficient operating limits.

• Industry standards: To optimize bandwidth and avoid diminishing returns, modern premium LED displays are engineered to lock into fixed refresh rates of either 3,840Hz or 7,680Hz.

 

The low-grayscale flickering challenge

While sub-period modulation handles bright imagery easily, it exposes a major industry pain point at the bottom end of the dimming curve.

• The low-light breakdown: At high grayscale levels, the signal can be divided into many short wavelengths to maintain high refresh rates. At low grayscale levels (dark scenes), the wavelength cannot be further subdivided.

• The 60Hz drop: At the very first grayscale level, the operational refresh rate can plummet down to 60Hz, causing visible flickering and eye strain.

The 120Hz frame rate fix: One of the most effective methods to combat low-grayscale flickering is upgrading the baseline frame rate from a conventional 60Hz to 120Hz, which instantly doubles the refresh rate across all gradients. However, this approach demands a more robust system hardware architecture and controller infrastructure to handle the increased data load.