Patent number US 8,517,577 B2
The Production Resource Group (PRG) was awarded an interesting patent on braking for moving lights. Specifically, this brake system act in the same manner that a truck’s air brakes work and is applicable to the motors of a moving light.
Under ordinary circumstances, when a moving light is de-energized, the head will fall in whatever direction that gravity may pull it. When moving the light, most lighting fixtures have mechanical locks activated manually to prevent moving. This creates two inherent problems: (1) if a light loses power while in use, the head falls to different position, and (2) when removing a light from the case and rigging it, it is not uncommon to forget to disengage the brake, causing all sorts of problems.
The title of the patent is “Pan and Tilt Servomotor with Brake”. However, the title of patent is not normally a limiting factor on the claimed invention. When reading the written description and claims of the patent, it does not appear that the claimed invention is limited to only servo motor for pant and tile in moving lights and will probably also apply to stepper motors more commonly utilized in moving lights. Whether this might be grounds for future invalidation from prior art remains to be seen.
Patent number US 8,517,577 B2 is available here.