Projection display apparatus and method of controlling the same

1. A projection display apparatus for projecting and displaying image light onto a projection plane, comprising:

an image light generator that generates the image light by modulating light emitted from a light source according to an input image signal;

a projection optical system including a projection lens that projects the image light onto the projection plane so that the image is magnified;

a focus controller that controls focusing of the projection lens; and

a temperature sensor that detects a temperature of the projection display apparatus,

wherein the focus controller operates to:

calculate a plurality of focus deviation amounts which correspond respectively to a plurality of component groups based on first information obtained from the image light generator and second information obtained from the temperature sensor, the plurality of component groups being classified depending on kinds of components constructing the projection optical system;

calculate a focus correction amount according to the plurality of focus deviation amounts having been calculated; and

control the focusing based on the focus correction amount having been calculated.

2. The projection display apparatus according to claim 1 , wherein the plurality of component groups include:

a first component group that causes a focus deviation amount to be substantially constant in a specific first time period;

a second component group that causes a focus deviation amount to be substantially constant in a specific second time period which is longer than the first specific time period, and

wherein the focus controller includes a storage unit that stores a focus correction amount table for calculating the focus correction amount corresponding to each of the first and second component groups in response to each of the first information and the second information and calculates the focus correction amount based on the focus correction amount table.

3. The projection display apparatus according to claim 1 , wherein the first information is a light intensity of the image light obtained by correcting an ideal light intensity having been calculated from the image signal based on degradation information of the light source.

4. The projection display apparatus according to claim 1 , wherein the second information is a temperature of the projection display apparatus.

5. The projection display apparatus according to claim 1 , wherein the focus controller calculates the focus correction amount according to a projecting time over which the image light has been projected.

6. The projection display apparatus according to claim 1 , wherein the focus controller controls the focusing at intervals of a specific time period after turning on the light source.

7. A method of controlling focusing of a projection display apparatus, the method comprising the steps of:

obtaining first information from an image light generator that generates image light by modulating light emitted from a light source according to an input image signal;

obtaining second information from a temperature sensor that detects a temperature of the projection display apparatus;

calculating a plurality of focus deviation amounts which correspond respectively to a plurality of component groups based on the first information and the second information, the plurality of component groups being classified depending on kinds of components constructing a projection optical system of the projection display apparatus; and

calculating a focus correction amount according to the plurality of focus deviation amounts having been calculated and controlling the focusing based on the focus correction amount having been calculated.