Image display device and laser light source device including multiple laser elements whose light amounts are individually measured

A laser light source device that is mounted in an image display device that includes a spatial modulation element configured to modulate a laser beam and generate an image that is to be projected on a screen, and outputs the laser beam to the spatial modulation element, the laser light source device comprising:

• a plurality of laser elements having different output wavelengths;
• a pulse signal generating unit that generates pulse signals individually 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 the 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 by starting and ending measurement during an on state of the pulse signal, when the pulse signal generating unit is of perating 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 signal, the predetermined period 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.