Image display device
A change in the white balance caused due to the temperature is reduced in an image display device using MEMS and a laser light source. An image processing unit of the device superposes a signal based on a first measured value of a light quantity at a first temperature on a image signal to be supplied to the laser light source. An amplification factor of the light source drive unit is changed so that a second measured value at a second temperature comes close to the first measured value at the first temperature as a target value based on the second measured value at which the light quantity of light generated at the laser light source is measured at the second temperature different from the first temperature on the signal based on the first measured value.
1. An image display device that externally projects generated light and displays an image, the image display device comprising:
a light source configured to generate the light;
a light source drive unit configured to drive the light source and control a light quantity of the light;
a reflecting mirror configured to reflect light generated at the light source and externally project the light, a direction to reflect the light being movable;
a reflecting mirror drive unit configured to drive the reflecting mirror and control the direction to reflect the light;
an image processing unit configured to process a first image signal inputted to the image display device, supply and control a second image signal for the image externally displayed to the light source drive unit, and supply a synchronization signal for the second image signal to the reflecting mirror drive unit;
an optical sensor configured to measure a light quantity of light generated at the light source and supply a measured value to the image processing unit; and
a temperature sensor configured to measure a temperature of the light source and supply a measured value to the image processing unit,
wherein the image processing unit superposes a signal based on a first measured value of the light quantity measured at the optical sensor on the second image signal to be supplied to the light source drive unit in a state in which the light source drive unit is set to drive the light source at a set first temperature; and
the image processing unit controls the light source drive unit so that a second measured value at a second temperature comes close to the first measured value at the first temperature as a target value based on the second measured value at which a light quantity of light generated at the light source is measured at the optical sensor at the second temperature different from the first temperature on the signal based on the first measured value.
2. The image display device according to claim 1 , wherein the state in which the light source drive unit is set to drive the light source depends on a current value at which the light source drive unit drives a light source.
3. The image display device according to claim 2 , wherein the first measured value at the first temperature and the second measured value at the second temperature are measured values of current values at two points at which the light source drive unit drives a light source.
4. The image display device according to claim 3 ,
wherein the light source includes a red light source, a green light source, and a blue light source; and
the image processing unit controls the light source drive unit so that the light source drive unit increases a current amplification factor of the red light source when a temperature of the red light source measured at the temperature sensor is increased, the light source drive unit reduces a current amplification factor of the green light source when a temperature of the green light source is increased, and the light source drive unit reduces a current amplification factor of the blue light source when a temperature of the blue light source is increased.
5. The image display device according to claim 4 , wherein the current amplification factor is set using a linear function for a light source temperature.
6. The image display device according to claim 1 ,
wherein the light source includes a red light source, a green light source, and a blue light source; and
the image processing unit controls the light source drive unit so that the light source drive unit increases a current amplification factor of the red light source when a temperature of the red light source measured at the temperature sensor is increased, the light source drive unit reduces a current amplification factor of the green light source when a temperature of the green light source is increased, and the light source drive unit reduces a current amplification factor of the blue light source when a temperature of the blue light source is increased.
7. The image display device according to claim 1 ,
wherein the image processing unit superposes the signal based on the first measured value of the light quantity at a left end or a right end of a vertical blanking period of the second image signal, and reduces the first image signal so that the superposed signal does not overlap with an effective display region of the first image signal.
8. The image display device according to claim 7 , further comprising a light shielding plate configured to shield light according to the signal based on the first measured value of the light quantity when the reflecting mirror externally projects the light.
9. The image display device according to claim 1 , wherein the light source is a light source using a laser diode.