At the time-dependant change amendment device null photosensor

摘要

PPROBLEM TO BE SOLVED: To provide a changes-over-time compensation apparatus capable of appropriately compensating a white balance in a projection display at any time. PSOLUTION: Regarding the changes-over-time compensation apparatus for the projection display, the light quantity of an image projected in a specified area on a screen is measured by an optical sensor, and whether or not RGB signals show uniform distribution in an area corresponding to the specified area of the input image is judged, and when it is judged that the RGB signals show the uniform distribution, the light quantity measured by the optical sensor and the RGB signal values in the area of the input image at this time are stored, and the light quantity of each one of RGB is calculated based on the relation between the stored light quantity and the stored RGB signal values, and every calculated light quantity of RGB is compared with the light quantity of RGB at the initial adjustment, and the reduction ratio is calculated, and the color outputs of other light sources are controlled so as to align with the color output of the light source showing the worst reduction ratio among the RGB light sources, then, the changes over time in the white balance is compensated. PCOPYRIGHT: (C)2007,JPO&INPIT