Light amount adjusting device, projection device, and light amount adjusting method

A projection device comprising:

• a light source unit that emits illumination light;
• an illumination optical system into which the illumination light enters from the light source unit, and which emits the illumination light;
• a projection optical system that projects the illumination light emitted from the illumination optical system onto a screen;
• a light amount adjusting unit that adjusts an amount of the illumination light;
• an optical sensor that detects a brightness of the illumination light and a light intensity of each of all color components of red, green, and blue included in the illumination light;
• a light-modulation element that light-modulates each of the color components of red, green, and blue included in the illumination light and outputs a projection video;
• and
• a gain adjusting unit that adjusts gain values of each of the color components output from the light-modulation element, wherein
• at a first time point,
• the light amount adjusting unit stores the brightness of the illumination light as a first brightness for the projection video to have a desired brightness, and stores a light intensity of each of the color components of the illumination light as a first light intensity,
• the gain adjusting unit sets the projection video to have a desired color and sets a gain value of at least one of the color components to be a maximum value, and stores the set gain value as a first gain value,
• at a second time point after the first time point,
• the light amount adjusting unit adjusts the amount of the illumination light so that the brightness of the illumination light emitted from the light source unit coincides with the first brightness, and calculates a ratio between a second light intensity and the first light intensity, the second light intensity being a light intensity of each of the color components of the illumination light emitted from the light source unit,
• the gain adjusting unit corrects the gain values based on the ratio between the second light intensity and the first light intensity, and if the corrected gain values exceed the maximum value, reduces the gain values of the color components at the same ratio so that the largest gain value among the gain values of the color component becomes the maximum value, and
• the light amount adjusting unit increases the amount of the illumination light.

A light amount adjusting method comprising:

• at a first time point,
• storing a brightness of illumination light emitted from a light source unit as a first brightness for a projection video to have a desired brightness, and storing a light intensity of each of all color components of red, green, and blue of the illumination light as a first light intensity,
• setting the projection video to have a desired color and setting a gain value of at least one of the color components to be a maximum value, and storing the set gain value as a first gain value,
• at a second time point after the first time point,
• adjusting an amount of the illumination light so that the brightness of the illumination light emitted from the light source unit coincides with the first brightness, and calculating a ratio between a second light intensity and the first light intensity, the second light intensity being a light intensity of each of the color components of the illumination light emitted from the light source unit,
• correcting the gain values based on the ratio between the second light intensity and the first light intensity, and if the corrected gain values exceed the maximum value, reducing the gain values of the color components at the same ratio so that the largest gain value among the gain values of the color component becomes the maximum value, and
• increasing the amount of the illumination light.