When the AR technology adopts the VST technical path, the final form of the headset is manifested as VR and MR, which is a closed-type interactive experience isolated from the external environment.
At this time, the display of the device is equivalent to the light source in the interactive environment, and thus the requirement for eye protection arises.
The traditional technology uses the Blanking Insert technology to reduce motion blur. For example, with 20% PWM black insertion, within the time of one frame, the screen is on for 20% of the time and off for 80% of the time, being in the off state for most of the time. To reduce the influence of motion blur, many VR systems will continue to increase the proportion of the display-off time, but this will lead to more severe screen flicker and cause harm to human eyes.
According to the internationally accepted IEEE Std 1789™ - 2015, when the flicker frequency of the display is less than 1250Hz, it is very likely to cause harm to human eyes; when it is greater than 1250Hz but less than 3125Hz, the risk of harm to human eyes is relatively low; only when it reaches above 3125Hz can the display flicker not cause harm to human eyes, reaching a zero-risk state.
The existing black-frame-insertion technology usually causes stroboscopic flicker with a frequency of only 90 - 120Hz, which will cause harm to human eyes after long-term use. The digital driving technology has achieved a flicker frequency of above 3600Hz, reaching a safe and eye-friendly state.
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