Patent ID: 7474453
Filing Date: 2009-01-06
Classification: G02B,G02F,G03B,H04N

Abstract:
1. A control apparatus for an optical density changing element that is used under the condition of EV=8.4 or higher comprising: an electromotive force generating element comprising an electromagnetic wave sensor and a voltage source, wherein the electromotive force generating element generates an electromotive force; an optical density changing element that has a change in optical density at a light amount in which EV has a value of 8.4 or higher including an electrochromic material driven by the electromotive force; and a resistor connected in parallel to the optical density changing element; wherein the optical density changing element consists of a pair of an anode and a cathode; and includes at least two different electrochromic materials that change optical densities at different wavelengths between the pair of the anode and the cathode.