Phthalocyanine electrochromic display

• US 4,184,751 A
• Filed: 10/04/1978
• Issued: 01/22/1980
• Est. Priority Date: 12/20/1976
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Nicholson, Margie M.
• Primary Examiner(s): Davie, James W.
• Application Number:
  US05/948,364
• Time in Patent Office: 475 Days
• Field of Search: 350/357, 252/408
• US Class Current: 359/275
• CPC Class Codes: G02F 1/1516 comprising organic material
• CPC Class Codes: G02F 1/1525 characterised by a particular ion transporting layer, e.g. electrolyte
• CPC Class Codes: G02F 1/1533 structural features not otherwise provided for
• CPC Class Codes: G02F 1/155 Electrodes

Abstract

An electrochromic display utilizing a metal diphthalocyanine complex as the electrochromic material is disclosed. Displayed information can be switched in less than 100 milliseconds. The display has multicolor and color reversal capabilities.

Claims

1. A low power, rapid switching, electrochromic display device comprising:

housing means including a substantially transparent viewing surface;

display electrode means disposed within said housing for being viewed through said viewing surface;

electrochromic material means disposed as a film within said housing over said display electrode means and in conductive relationship thereto, said electrochromic material means including an electrochromic metal-diphthalocyanine complex;

electrolyte means disposed within said housing in conductive relationship to said electrochromic film;

counterelectrode means disposed within said housing in electrically conducting relationship to said electrolyte means;

lead means for connecting said dipslay electrode means and said counterelectrode means to a display control circuit;

said lead means, said electrochromic material means, said display electrode means, said electrolyte means and said counterelectrode means together comprising a structure exhibiting an apparent capacitance and an apparent resistance, said lead means, said display elecrrode means, said electrolyte means and said counterelectrode means being sufficiently conductive that said apparent resistance of said structure and said apparent capacitance of said structure combine to provide an RC time constant of one second or less.

2. The low power rapid switching electrochromic display device recited in claim 1 wherein said RC time constant is equal to or less than 100 milliseconds.

3. The display device recited in claim 1 wherein:

said housing means includes a light transmissive portion in optical alighment with said viewing face;

said display electrode means are light transmissive; and

said electrolyte means is light transmissive whereby said display can be viewed by transmitted light.

4. The display device recited in claim 1 wherein said display electrode means include:

character segment means configured and disposed to be selectively activatable to form characters selected from a predetermined set; and

background segment means configured and disposed to form a background area against which characters formed by said character segment means are to be viewed so that where selected character segment means defining a selected character are in a first optical state and any non-selected character segment means and said background segment means are in a second optical state, said selected character is displayed in the color exhibited in said first optical state against a background of the color exhibited in said second optical state and when said selected character segment means are in said second optical state and the nonselected character segment means and said background segment means are in said first optical state, said selected character is displayed in said color exhibited in said first optical state.

5. The display device recited in claim 1 wherein said electrolyte means comprises an inert porous solid saturated with an aqueous solution of potassium chloride.

6. The electrochromic display device recited in claim 1 further comprising reference electrode means distinct from said counterelectrode means for establishing the potential of said display electrode means in said electrolyte means.

7. The display device recited in claim 6 wherein:

said electrochromic material means comprises a lutetium diphthalocyanine complex;

said electrolyte means comprises an inert porous solid saturated with an aqueous solution of potassium chloride; and

said reference electrode is selected from the group consisting of silver, lead, mercury and silver, lead or mercury having a film of the chloride thereof thereon.

8. The display device recited in claim 1 wherein said electrochromic material means is one which may be controllably placed in at least three different optical states each of which exhibits a different color.

9. The display device recited in claim 8 wherein said electrochromic material means comprises a lutetium diphthalocyanine complex, and said electrolyte means comprises an inert porous solid saturated with an aqueous solution of potassium chloride such that the display device can exhibit the colors lavender, blue, turquoise, green, yellow or tan shades and red, in accordance with the level on the electrochemical scale at which said display electrode means is maintained.

10. The display device recited in claim 1 wherein said electrochromic material means includes a transparent porous binder for preventing deterioration of the display characteristics of said metaldiphthalocyanine complex.

11. A display cell capable of assuming at least three visually distinct optical states comprising,

transparent display electrode means,

said transparent display electrode means comprising a transparent conductor having sheet resistance of less than about 15 ohms per square,

counterelectrode means for establishing a potential difference relative to said display electrode means,

said counterelectrode means comprising highly conductive material,

a film of electrochromic material disposed on said display electrode means,

an electrolyte material interposed between said film on said display electrode means and said counterelectrode means in order to pass ionic current therethrough,

said cell constructed so that the apparent capacitance C of the cell and the resistance R of the respective electrode means and said counterelectrode means exhibit an RC time constant of not more than one second, and

a reference electrode in contact with said electrolyte material to establish a stable electrochemical potential despite the passage of current through said display cell.

12. The display cell recited in claim 11 wherein

said display electrode means comprises an array of segment electrodes for defining a character and an array of background electrodes associated with said segment electrodes to further define said character.

13. The display cell recited in claim 11 wherein each of said visually distinct optical states exhibits a different color.