Method for light diffusion through a window

A method for controlling a smart window with a light diffuser configured to be driven by a driving mechanism powered by an output power of a solar panel, the method comprising:

• storing a predetermined condition to cause a positional transition of the light diffuser and a positional information of a predetermined opened position as an initial condition;
• monitoring the output power of the solar panel;
• comparing the output power of the solar panel with a predetermined value;
• making decision whether a positional transition is necessary for the light diffuser;
• and
• either
• a) causing a transition of the light diffuser from the predetermined opened position to a closed position via the driving mechanism, when the output power of the solar panel is not smaller than the predetermined value for longer than a predetermined time duration while the light diffuser is at the predetermined opened position;
• b) causing a return of the light diffuser from the closed position to the predetermined opened position when the output power of the solar panel is smaller than the predetermined value for longer than the predetermined time duration, or
• c) maintaining a current position when conditions for a) or b) is not satisfied;
• wherein the light diffuser comprises:
• a base plate transparent to visible light, and light diffusing element on the base plate, wherein the light diffuser is aligned at a predetermined opened position initially;
• a light diffuser positioner configured to move the light diffuser between the predetermined opened position and the closed position;
• wherein the driving mechanism comprises an axial rotation motor, a latch mechanism configured to latch a motion of the driving mechanism, and a transmission mechanism having a gear transmission configured to transmit the motion of the motor to the light diffuser positioner;
• wherein the solar panel is mounted on a frame of a smart window diffuser device;
• and
• a control unit comprising a memory, a monitor of the output power from the solar panel, a controller and a power source,
• wherein the memory is configured to store a predetermined threshold output power of the solar panel, a predetermined duration time, and a present position of the light diffuser,
• wherein the monitor is configured to receive the output power from the solar panel and send a monitor signal to the controller,
• wherein the controller is configured to control the driving mechanism, and
• wherein the power source is configured to supply an electric power required for an operation of the smart window diffuser device,
• wherein the control unit is configured to:
• move the light diffuser to the closed position via the light diffuser positioner and the driving mechanism, and to hold the light diffuser at the closed position with the latch mechanism when following two conditions are satisfied:
• 1) the output power of the solar panel is not smaller than the predetermined output power for longer than the predetermined duration time;
• and
• 2) The light diffuser is at the predetermined opened position,
• and wherein the control unit is further configured to
• release the latch mechanism and cause the light diffuser to return to the predetermined opened position when following two conditions are satisfied;
• 1) the output power of the solar panel lowers to a value smaller than the predetermined output power for longer than the predetermined duration time;
• and
• 2) The light diffuser is at the closed position, and
• wherein the light diffuser is configured to transmit incident direct solar radiation therethrough toward an interior direction of a building such that the solar radiation transmitted through the light diffuser is converted to a diffusive light when the light diffuser is at the closed position, and to admit the incident direct solar radiation into interior of the building without being blocked by the light diffuser when the light diffuser is at the predetermined opened position, and
• wherein the light diffuser includes a diffractive diffuser disposed on an interior side surface of the base plate.