FOCUS ADJUSTMENT DEVICE AND FOCUS ADJUSTMENT METHOD, AND PROJECTION DEVICE AND CONTROL METHOD OF THE PROJECTION DEVICE

摘要

PROBLEM TO BE SOLVED: To enable appropriate auto-focus control in a projection device.SOLUTION: A distance value output unit outputs a distance value indicative of a measured distance from a projection part to a projection target medium. A focus adjustment unit adjusts a focus of light passing the projection part. A focus adjustment driving unit uses the distance value as a first distance value to detect a first deviation from an in-focus state of light projected on the projection target medium by the projection part, on the basis of the first distance value and drives the focus adjustment unit so that a value indicative of the first deviation is 0. A determination unit uses the distance value as a second distance value to detect a second deviation from the in-focus state of the light on the basis of the second distance value and determines whether a value indicative of the second deviation is smaller than a threshold or not. When the determination unit determines that the threshold is a first value and that the state where the value indicative of the second deviation is smaller than the threshold has continued for a preliminarily determined time or longer, the threshold in the determination unit is set to a second value larger than the first value, and update of the first distance value in the focus adjustment driving unit is stopped.