| 摘要 |
PURPOSE:To improve accuracy without using a mirror and to make a range- finding optical system simple and compact by using results obtained by measuring the tilt angle of the mirror and a distance to a screen where an image is projected so that the difference of projection distance from the mirror to the screen is corrected and performing the autofocusing of a projecting lens. CONSTITUTION:The projecting lens 10 enlarges the image and a distance sensor 20 measures the distance to the screen where the image is projected without using the mirror 11. A detection means 13 converts the tilt angle of the mirror 11 into an electrical signal. A processing means corrects the projection distance from the results obtained by measuring the angle of the mirror and the distance and performs the autofocusing of the projecting lens 10. Therefore, the reflection of the signal of light, etc., by the mirror need not be used in order to measure the distance. Thus, the distance to the screen is measured without using the mirror when it is measured and the accurate autofocusing of the projecting lens is performed based on the distance to the screen surface, thereby making the range-finding optical system compact. |
