Electrochromic display device having auxiliary electrode

Claim 1

An electrochromic display device comprising: two transparent substrates which are held opposite to and spaced from each other and each of which is laid with a transparent electrode film on the side facing the other substrate; a first electrochromic layer which is formed on the transparent electrode film on one of the two substrates and is formed of a first electrochromic material which takes on color in its electrochemically oxidized state; a second electrochromic layer which is formed on the transparent electrode film on the other of the two substrates and is formed of a second electrochromic material which takes on color in its electrochemically reduced state; an electrolyte which occupies the space between the two substrates; an auxiliary electrode disposed in a marginal region of the space between the two substrates for use in initial reduction of one of the first and second electrochromic layers, the auxiliary electrode comprising an electrode body comprising an electroconductive material and an electrochemically oxidizable and reducible substance, two insulating layers laid directly on opposite surfaces of said electrode body to intervene between said electrode body and the transparent electrode films on the two substrates and to insulate said electrode body from the two transparent electrode films, each of said two insulating layers being an organic polymer sheet which is substantially impermeable to ions, and an insulating covering which is permeable to ions and at least partially covers said electrode body such that said insulating covering intervenes between said electrolyte and said electrode body, said insulating covering being wrapped around said electrode body and said two insulating layers.