Dynamic scattering, guest host, non-glaring reflector

• US 4,664,479 A
• Filed: 11/18/1985
• Issued: 05/12/1987
• Est. Priority Date: 12/16/1982
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Hiroshi, Itoh
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Lewis, David
• Application Number:
  US06/799,191
• Time in Patent Office: 540 Days
• Field of Search: 350/349, 350/340, 350/341, 350/334, 350/338, 350/279, 350/278, 350/283
• US Class Current: 349/195
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence

Abstract

A non-glaring type reflector employing a liquid crystal layer which is composed of a liquid crystal matrix and dichroic coloring matter, which provides a dynamic scattering effect or phase transition effect by applying an electric field. Except on the non-glaring operation, the molecular orientation of the liquid crystal matrix and dichroic coloring matter is uniform to cause a transparent state. On the non-glaring operation, however, the molecular orientation is random, thereby scattering the incident light by the liquid crystal matrix. The scattered light is then absorbed by a dichroic coloring matter to result in a decreased reflectance. The reflectance is controlled by applying a voltage into a liquid crystal layer.

Claims

1. A non-glaring liquid crystal type mirror arrangement for a rear view mirror of a vehicle, comprising:

a pair of electrodes;

a liquid crystal layer, disposed between said electrodes, including a liquid crystal and a transparent dichroic coloring mather and having a uniform molecular axis orientation in the absence of an electric field, said molecular axis orientation being controlled in response to an electric field applied across said electrodes;

a first transparent substrate placed at a first surface of said liquid crystal layer;

a second substrate placed at a second surface of said liquid crystal layer, said second substrate including a reflection layer to reflect light incident thereon;

wherein;

said liquid crystal layer is transparent when no electric field is applied such that light incident on said first surface of said liquid crystal layer passes through said first transparent substrate and said liquid crystal layer to said reflection layer and reflects off said reflection layer, the reflected light passing through said liquid crystal layer and said first transparent substrate again; and

wherein;

said liquid crystal exhibits a dynamic scattering effect causing reflected light to be scattered when an electric field is created by applying a voltage between said pair of electrodes such that light incident on said first surface of said liquid crystal layer passes through said first transparent substrate and said liquid crystal layer to said reflection layer and reflects off said reflection layer, the reflected light being scattered by said liquid crystal layer and absorbed by said dichroic coloring matter, said electric field being applied to said electrodes at times necessary to prevent light reflection from said rear view mirror from dazzling the driver of said vehicle.

2. A non-glaring liquid crystal type mirror arrangement according to claim 1, wherein said dichroic coloring matter comprises 0.3-3% by weight of said liquid crystal layer.

3. A non-glaring liquid crystal type mirror arrangement according to claim 1, wherein said uniform molecular axis orientation is perpendicular to said substrate when no electric field is applied.

4. A non-glaring liquid crystal type mirror arrangement according to claim 1, further comprising:

a photoconductive device for measuring the brightness of light incident on said first surface of said liquid crystal layer; and

a liquid crystal control circuit for applying said voltage between said electrodes when said photoconductive device has a conductivity greater than a predetermined value.

5. A non-glaring liquid crystal type mirror arrangement for a rear view mirror of a vehicle, comprising:

a liquid crystal layer including a liquid crystal and a transparent dichroic coloring matter and having a uniform molecular axis orientation in the absence of an electric field, said molecular axis orientation being controlled in response to an applied electric field;

a first transparent substrate placed at a first surface of said liquid crystal layer;

a second substrate placed at a second surface of said llquid crystal layer, said second substrate including a reflection layer to reflect light incident thereon, said reflection layer also functioning as a first electrode;

a second electrode placed at said first surface of said liquid crystal layer adjacent said first transparent substrate;

wherein;

said liquid crystal layer is transparent when no electric field is applied such that light incident on said first surface of said liquid crystal layer passes through said first transparent substrate and said liquid crystal layer to said reflection layer and reflects off said reflection layer, the reflected light passing through said liquid crystal layer and said first transparent substrate again; and

wherein;

said liquid crystal exhibits a dynamic scattering effect causing reflected light to be scattered when an electric field is created by applying a voltage between said first and second electrodes such that light incident on said first surface of said liquid crystal layer passes through said first transparent substrate and said liquid crystal layer to said reflection layer and reflects off said reflection layer, the reflected light being scattered by said liquid crystal layer and absorbed by said dichroic coloring matter, said electric field being applied to said first and second electrodes at times necessary to prevent light reflection from said rear view mirror from dazzling the driver of said vehicle.