Donnelly Mirrors Limited

Donnelly Corporation

Keith W Molyneux

Kenneth Schofield

Niall R Lynam

Edward A Gahan

Thomas D Gaffney

A fluid composition for use in a rearview mirror of the type which contains a U.V. stable fluid light controlling medium, the composition consisting of a solvent, e.g., propylene carbonate, with a freezing point less than -30.degree. C. and a boiling point greater than 80.degree. C., a dye or mixture of dyes, e.g., a 1,2-chrome dye and a phthalocyanine dye, which is soluble in the solvent and optionally a U.V. stabilizing agent, e.g., a benzophenone, benzotriazole or organo-nickel complex, which is also soluble in the solvent. The dye or mixture of dyes has specifically defined light absorbance characteristics and in use is a fluid which is nontoxic, easy to handle, has a relatively high flash point, and is relatively inert to glass, rubbers and plastics.

Fluid light controlling medium for a vehicle rearview mirror

The invention provides an automatic rearview mirror system (10) for a vehicle comprising a reflective element (22) actuatable between at least two different reflective conditions. The system includes a forward light sensor (11) to detect light forward of the vehicle and a rear light sensor (12) to detect light rearward of the mirror. A control circuit means (14,16) is coupled to the reflective element (22), the forward light sensor (11) and the rear light sensor (12). The control circuit causes the reflective element to assume a reflective state dependent upon the output of the forward and rear light sensors. The control circuit includes means for modifying the output of the forward light sensor (11) to cause a reduction in the sensitivity of the mirror.

Control circuit for an automatic rearview mirror

The specification discloses an automatic rearview mirror control circuit which models the physiological response of the human eye to fluctuating light levels as observed in typical driving conditions. The control circuit calculates an ambient light signal representative of light levels within the driver's field of view and a rear light signal representative of light levels in a direction generally incident to the reflective element. The reflectivity of the reflective element is controlled to optimize rear image information while minimizing on rear image glare at the driver's eyes. The control circuit includes a multiple-rate filter for time-averaging an ambient light signal over a shorter time period during increasing ambient light intensities than during decreasing ambient light intensities to simulate the more rapid adaptation of the human eye to increasing light intensities than to decreasing light intensities. The control circuit automatically alters or adjusts the sensitivity of the mirror to rear light based on the ambient light level. The mirror is more sensitive to rear light in relatively low ambient light, such as experienced on rural highways, than in relatively high ambient light, such as is experienced on urban highways. The control circuit calculates ambient light within the driver' s field of view. The calculation takes into account the forward light, rear light reflected from the interior rearview mirror, and/or rear light reflected from the windshield, pillars, headliner, and exterior rearview mirrors.

Rearview mirror control circuit

A casing has a transparent window plate sealed therein. A reflector plate is mounted on a diaphram which forms a sealed chamber with the rearwall of the casing. The casing is mounted on a conventional mirror adjustment mechanism. A plurality of conical compression springs urge the reflector plate against the inside surface of the window plate in the day position of the reflector plate. To move the reflector plate from a day position to a night position, a pump draws an optically dense light attenuating fluid from a reservoir and pumps it into an annular chamber and between the window plate and reflector plate, to move the reflector plate rearwards so that the fluid forms a masking layer between the reflector plate and window plate. The masking layer extinguishes reflections from the reflector plate in the night position. A solenoid valve prevents return of the fluid to the reservoir in the night position.

Growing community of inventors

Ballymore Eustace, Ireland

Keith W Molyneux