Projection display device

1 . A projection display device comprising:

a liquid crystal panel including a panel pixel;

an optical path shifting element configured to shift an optical path of projection light projected from the panel pixel to cause a position of a projected pixel displayed by the projection light to be different for each of k unit periods from a first unit period to a kth unit period included in one frame period, k being an integer that is equal to or larger than two; and

a display control circuit configured to control the liquid crystal panel and the optical path shifting element, wherein

the display control circuit

supplies a data signal corresponding to a gradation level designated by video pixel data forming video data, to the panel pixel in each of the unit periods, and

controls, by the optical path shifting element, the projection position for each of the unit periods,

the optical path shifting element shifts, for each of the unit periods, the projection light to a target projection position which is a target, by first shifting the projection light to the target projection position, then passing the projection light through the target projection position and shifting the projection light away from the target projection position, and returning the projection light to the target projection position after the projection light has passed through the target projection position, and

in one of the unit periods, the optical path shifting element shifts the projection light to the target projection position along a first direction and, after the projection light has reached the target projection position, passed through the target projection position and shifted away from the target projection position along the first direction, shifts the projection light back to the target projection position along a second direction that is opposite to the first direction.

2 . The projection display device according to claim 1 , wherein shifting from an immediately preceding target projection position in a unit period before one unit period to one target projection position in the one unit period occurs with a maximum separation distance from the immediately preceding target projection position being one or more pixels, the pixels being the panel pixels.

3 . The projection display device according to claim 2 , wherein the optical path shifting element shifts the projection position from the immediately preceding target projection position to an opposite position with respect to the one target projection position, and then returns the projection position to the one target projection position.

4 . The projection display device according to claim 1 , wherein the optical path shifting element causes the projection position to shift from an immediately preceding target projection position and turn at the one target projection position and then return, in a clockwise or counterclockwise direction as viewed on the projection surface, to the one target projection position.

5 . The projection display device according to claim 1 , wherein the optical path shifting element causes the projection position to move straight from an immediately preceding target projection position to the one target projection position and then return, in a clockwise or counterclockwise direction as viewed on the projection surface, to the one target projection position.