US Patent 8254013 Controlling transitions in optically switchable devices

A controller or control method may be designed or configured to operate without information about the current temperature of the device and/or the device's environment. Further, in some cases, the controller or control method is designed or configured to control transition of an optical device to an intermediated state between two end states. For example, the controller may be configured to control a transition to a state of transmissivity that is intermediate between two end states of transmissivity. In such case, the device has three or more stable states of transmissivity.