From the patent ("Detailed Description of the Preferred Embodiments"):
"The electrical pulses as shown in FIG. 3 have varied pulse widths because of the operation of PWM, and their actual pulse widths depend on the associated sinusoidal duty cycle function. The PWM frequency used in this embodiment is 125 Hz. In fact, preferred frequencies include any frequency sufficiently greater than that can be effectively distinguished by the human eye. However, power consideration for portable devices further prefer PWM frequencies to range within, for example, 100-200 Hz. ... It was determined through experiment that increasing the duty cycle according to a non-linear function gives the most pleasing visual effect while a simple linear ramp does not seem as natural."
This is consistent with what I claim. I never sad the apple indicator light was 60hz, I was just using that as an example as it's a very common frequency; I notice it especially with antennae, bridges, buildings, etc.
Take a camera and set the shutter speed long enough so that you can blur the light, and you'll see the blinking effect that I do. The patent can claim it's not noticable, but it's pretty noticable to me. Interesting that they market even in their patents.
Yes... Motion pictures, for example, are 24hz-30hz, which is just enough to get rid of noticeable flicker, but still risks strobing during fast camera movements.
Another major factor in motion pictures is that each frame also contains a substancial amount of blur. This allows your mind to compensate for the lack of frames. I'm not sure how projectors work, exactly, but I suspect they also fade into and out of each frame in some way. That is, it probably doesn't operate like this: show frame -> clear screen -> show next frame.
LEDs and the like are usually set up to be either on or off (a square wave) causing the flicker much more apparent. Street lamps are sort of a hybrid, they "flicker" at 60hz, but their flicker is not a square wave, but rather a sine wave.
"The electrical pulses as shown in FIG. 3 have varied pulse widths because of the operation of PWM, and their actual pulse widths depend on the associated sinusoidal duty cycle function. The PWM frequency used in this embodiment is 125 Hz. In fact, preferred frequencies include any frequency sufficiently greater than that can be effectively distinguished by the human eye. However, power consideration for portable devices further prefer PWM frequencies to range within, for example, 100-200 Hz. ... It was determined through experiment that increasing the duty cycle according to a non-linear function gives the most pleasing visual effect while a simple linear ramp does not seem as natural."