Patent ID: 8801193

Claim:
An image display device comprising: a laser light source device that emits a laser beam; and a spatial modulation element that modulates the laser beam output from the laser light source device and thereby generates an image that is to be projected onto a screen, wherein the laser light source device further comprises: a plurality of laser elements of different output wavelengths; a pulse signal generating unit that generates pulse signals for the respective laser elements based on a video signal and an automatic power control (APC) scheme; a laser driving unit that receives the pulse signals and drives the laser elements in synchronization with the pulse signals; an optical combining system that combines laser beams from the laser elements and outputs a laser beam that is combined toward the spatial modulation element, and also retrieves part of the combined laser beam; a light amount measuring unit that receives each generated pulse signal and, on the basis of a signal width of the received pulse signal, selectively measures a light amount of a laser beam output according to the pulse signal and retrieved by the optical combining system; and a light amount adjusting unit that causes the laser driving unit to individually adjust a light amount for each of the laser elements based on a measurement value of the light amount selectively measured by the light amount measuring unit, wherein the pulse signal generating unit operates in a light amount measuring mode based on the APC scheme, in which APC-control pulse signals for the laser elements are generated sequentially in a predetermined order, so that emission timings of the laser elements would not coincide one another, and the APC-control pulse signals each would have a greater signal width than the pulse signals based on the video signal, the light amount measuring unit individually measures a light amount of each of the laser elements during an on state of each pulse signal by starting and ending measurement when the pulse signal generating unit is operating in the light amount measuring mode, and the light amount measuring unit selectively measures the light amount of the laser beam based on the signal width of each received pulse signal by delaying measurement until a predetermined period after a rising edge of the pulse singal, the predetermined peroid being longer than the signal width of each pulse signal generated based on the video signal and shorter than the signal width of each pulse signal generated based on the APC scheme.