Projection apparatus and method of image projection

Abstract

A projection apparatus generates an image (1) by projecting light representative of the image (1) on to a display screen (10). The apparatus (5) comprises at least one projector (20, 22, 24) operable to receive a component signal (IR, IB, IG) representative of a component of the image and to project light representative of the component on to the display screen (10), the projector having an adjustment means for adjusting the relative position of the projected image component on the display (10) screen in accordance with an adjustment signal, a convergence processor (120) coupled to the adjustment means and operable to adjust a relative position of the image component on the display screen in response to α measurement signal generated by a sensing device (SD, SD′) disposed with respect to the screen (10) in response to a test projection (150, 160, 220, 230, 240, 250, 260) received from the sensing device (SD, SD′), wherein the sensing device is operable to produce a measurement signal having a predetermined output value when the relative position of the test projection is substantially optimum, and the convergence processor (120) is operable to displace successively the test projection from a first position, by a predetermined amount, until the value of the measurement signal corresponds to the predetermined output value, the adjustment signal being set in correspondence with the relative displacement of the test projection (150, 160, 220, 230, 240, 250, 260) from the first position to the position at which the measurement signal corresponds to the predetermined output value. The predetermined value may be a null value, zero or substantially close to zero. The convergence processor may be implemented in hardware because the detection of the null value facilitates detection of the optimum alignment position, in accordance with a simplified alignment process.

Dependencies are inferred from the claim text.