Abstract: To provide a technique for facilitating control of a plurality of projectors. A projection display system comprises a plurality of projectors wherein a plurality of images projected by the projectors are displayed on a common projection screen. Each projector comprises: a control signal processor for processing a control signal given from an external device and generating a processed control signal; and a signal input/output section for input/output of the control signal and the processed control signal. The plurality of projectors are coupled in a cascade connection, by interconnecting the signal input/output sections of the projectors. The control signal and the processed control signal include connection sequence data indicating the cascade connection sequence. The control signal processor of each projector comprises a memory for storing, on the basis of a given control signal, a connection sequence when the projectors are coupled in a cascade connection.

Abstract: An automatic keystone correction which enables even an inexperienced user to easily obtain an image corrected using the keystone distortion during a tilted projection. The projector detects varying of its elevation angle by using an elevation detecting module. When the angle stops varying, the projector determines that the elevation adjustment by the user ends, and executes auto keystone correction of the input image according to the elevation angle.

Abstract: To provide a technique for facilitating control of a plurality of projectors. A projection display system comprises a plurality of projectors wherein a plurality of images projected by the projectors are displayed on a common projection screen. Each projector comprises: a control signal processor for processing a control signal given from an external device and generating a processed control signal; and a signal input/output section for input/output of the control signal and the processed control signal. The plurality of projectors are coupled in a cascade connection, by interconnecting the signal input/output sections of the projectors. The control signal and the processed control signal include connection sequence data indicating the cascade connection sequence. The control signal processor of each projector comprises a memory for storing, on the basis of a given control signal, a connection sequence when the projectors are coupled in a cascade connection.