Electrochromic display device, fabrication method therefor, and driving method therefor
An electrochromic display device includes a display substrate, a counter substrate facing the display substrate, counter electrodes formed on the counter substrate, at least first and second display electrodes arranged between the display substrate and the counter electrodes, the first display electrode and the second display electrode having a predetermined distance from each other, a first electrochromic layer arranged on the first display electrode and a second electrochromic layer arranged on the second display electrode, an electrolyte layer arranged between the respective first and the second display electrodes and the counter electrodes, and a protective layer made of an insulator material formed on a counter electrode facing side surface of one of the first and the second display electrodes such that the protective layer is sandwiched between the selected one of the first and the second display electrodes and a corresponding one of the first and the second electrochromic layers.
1. An electrochromic display device comprising:
a display substrate;
a counter substrate facing the display substrate;
an array of counter electrodes formed on the counter substrate;
at least a first display electrode and a second display electrode arranged between the display substrate and the array of the counter electrodes, the first display electrode and the second display electrode having a predetermined distance from each other;
a first electrochromic layer arranged on the first display electrode and a second electrochromic layer arranged on the second display electrode;
an electrolyte layer arranged between the first and the second display electrodes and the array of the counter electrodes; and
a protective layer made of an insulator material formed on a counter electrode facing side surface of one of the first and the second display electrodes such that the protective layer is sandwiched between the selected one of the first and the second display electrodes and a corresponding one of the first and the second electrochromic layers.
2. The electrochromic display device as claimed in claim 1 , wherein the insulator material includes a metallic oxide as a major component.
3. The electrochromic display device as claimed in claim 1 , wherein the protective layer includes a thickness less than a thickness of the selected one of the first and the second display electrodes on the counter electrode facing side surface of which the protective layer is formed.
4. The electrochromic display device as claimed in claim 3 , wherein the thickness of the protective layer formed on the counter electrode facing side surface of the selected one of the first and the second display electrodes is in a range of 0.5 to 5 nm.
5. The electrochromic display device as claimed in claim 3 , wherein in a case where the protective layer is formed on the counter electrode facing side surfaces of both the first and the second display electrodes as a first protective layer formed on the first display electrode and a second protective layer formed on the second display electrode, the first protective layer and the second protective layer include mutually different thicknesses.
6. The electrochromic display device as claimed in claim 1 , wherein the insulator material includes one of an Al oxide and a Si oxide.
7. The electrochromic display device as claimed in claim 1 , wherein the protective layer is formed by vacuum deposition.
8. The electrochromic display device as claimed in claim 1 , wherein voltages are applied between the first and the second display electrodes and the corresponding counter electrodes in the order of distance from farthest to closest between the first and the second display electrodes and the corresponding counter electrodes to subsequently drive the first and the second electrochromic layers to develop corresponding colors.