Screen device and image projection system

A screen device comprising:

• a screen;
• a plurality of photoelectric conversion elements on the screen comprising:
• a plurality of first photoelectric conversion elements being arranged at an outermost periphery, in a frame shape, of an area in which the plurality of photoelectric conversion elements are arranged, and
• a plurality of second photoelectric conversion elements being arranged inside of the outermost periphery covered by the plurality of first photoelectric conversion elements within the area in which the plurality of photoelectric conversion elements are arranged;
• a flying object configured to be powered by electric power generated by the plurality of second photoelectric conversion elements;
• a support member connecting the screen with the flying object;
• and
• a controller configured to control the flying object based on an evaluation of electric power generated by the plurality of first photoelectric conversion elements,
• wherein the controller is configured to determine whether the electric power generated by the plurality of first photoelectric conversion elements is less than a first reference value,
• wherein in response to the determination that the electric power generated by the plurality of first photoelectric conversion elements is less than the first reference value, the controller is configured to cause the flying object to move in a first direction,
• wherein in response to the determination that the electric power generated by the plurality of first photoelectric conversion elements is not less than the first reference value, the controller is configured to determine whether a total electric power generated by both the plurality of first photoelectric conversion elements and the plurality of second photoelectric conversion elements is less than a second reference value, the second reference value being larger than the first reference value, and
• wherein in response to the determination that the total electric power generated is less than the second reference value, the controller is configured to cause the flying object to move in a second direction, the second direction being an opposite direction of the first direction.