Automatic electrochromic control of light level of vacuum fluorescent display

• US 5,883,605 A
• Filed: 03/08/1996
• Issued: 03/16/1999
• Est. Priority Date: 02/25/1992
• Status: Expired due to Term

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Knapp, Robert C.
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): CHANG, KENT WU
• Application Number:
  US08/611,332
• Time in Patent Office: 1,103 Days
• Field of Search: 345/7, 345/74, 345/8, 345/87, 345/102, 345/9, 359/13, 359/603, 359/630, 359/604
• US Class Current: 345/7
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: G09G 3/06 using controlled light sources
• CPC Class Codes: G09G 3/22 using controlled light sources

Abstract

A vehicle having instrumentation indicative of parameters associated with the operation of the vehicle, which instrumentation includes variable intensity light emitting elements whereby the instrumentation will be appropriately displayed to the vehicle operator. A light sensing control system is provided for sensing varying light level conditions and generating corresponding electrical signals indicative of the varying light levels. The control system is responsive to the electrical signals and effective to vary the intensity of the light emitting elements over a range as a function of the varying light levels so that the instrumentation will remain visible to the vehicle operator, but not at a distracting brightness to the vehicle operator, during variable light level conditions. Another feature of the invention is the provision of a control for adjusting the intensity of the light emitting elements independently of glare causing light levels.

Claims

1. An electronic control system for controlling the reflective state of an automatic rearview mirror for an automotive vehicle, said system including a rearview mirror comprising an electro-optic variable reflectance mirror element the reflectivity of which varies over a reflectance range as a function of electrical signals applied thereto, said rearview mirror also including a variable luminance light emitting display visible through said electro-optic variable reflectance mirror element, ambient light sensing means effective to sense ambient light levels and to generate an electrical signal indicative of the ambient light level, glare light sensing means effective to sense glare-causing light levels and generate an electrical signal indicative of the glare-causing light level, means responsive to said electrical signals to control both the reflective state of said mirror element and the luminance of said light emitting display whereby the luminance of said display increases as the reflectivity of said electro-optic variable reflectance mirror element decreases and the luminance of said display decreases as the reflectivity of said mirror element increases, and means operable to vary the luminance of said light emitting display directly as a function of the electrical signal indicative of the ambient light level.

2. An electro-optically dimming rearview mirror for automotive vehicles, said mirror comprising, in combination, front and rear spaced elements, said front element and said rear element defining a chamber therebetween, said front element being transparent, the side of said front element confronting said rear element including transparent electrically conductive means, the side of said rear element confronting said front element including electrically conductive means, said rear element also including light reflecting means, said chamber containing an electro-optic reversibly variable light transmittance medium in contact with said transparent electrically conductive means on said front and rear elements, said light reflecting means on said rear element being effective to reflect light through said medium and through said front element when said light reaches said light reflecting means after passing through said medium and through said front element, said light reflecting means defining an opening, light emitting display means visible through said medium and through said opening defined by said light reflecting means, control circuitry including ambient light sensing means effective to sense ambient light levels and to generate corresponding electrical signals indicative of the ambient light levels, said control circuitry also including glare light sensing means effective to detect glare-causing light levels and generate corresponding electrical signals indicative of said glare-causing light levels, said control circuitry also including means operable to apply an electrical potential to said electrically conductive means whereby the light transmittance of said medium is varied as a function of the ambient light levels and the glare-causing light levels, means operable to vary the luminance of said light emitting display inversely with respect to variations in the light transmittance of said medium whereby the luminance of said display increases as the light transmittance of said medium decreases and the luminance of said display decreases as the light transmittance of said medium increases, and means operable to vary the luminance of said light emitting display directly as a function of the electrical signals indicative of the ambient light levels.

3. An electro-optically dimming rearview mirror for automotive vehicles, said mirror comprising, in combination, front and rear spaced elements, said front element and said rear element defining a chamber therebetween, said front element being transparent, said rear element also including light reflecting means, said chamber containing an electrochromic reversibly variable light transmittance medium, said light reflecting means on said rear element being effective to reflect light through said medium and through said front element when said light reaches said light reflecting means after passing through said medium and through said front element, said light reflecting means defining an opening, vacuum fluorescent display means visible through said medium and through said opening defined by said light reflecting means, control circuitry including ambient light sensing means effective to detect ambient light levels impinging thereon and generate a corresponding electrical signal indicative of said ambient light levels, said control circuitry also including glare light sensing means effective to detect glare-causing light levels impinging upon said light reflecting means and generate a corresponding electrical signal indicative of said glare-causing light levels, said control circuitry also including means operable to apply an electrical potential to said medium whereby the light transmittance of said medium is varied as a function of the ambient light levels and the glare-causing light levels, and means operable to vary the luminance of said vacuum fluorescent display inversely with respect to variations in the light transmittance of said medium whereby the luminance of said display increases as the light transmittance of said medium decreases and the luminance of said display decreases as the light transmittance of said medium increases, and means operable to modify the luminance of said vacuum fluorescent display directly as a function of the electrical signals indicative of the ambient light levels and independently of the electrical signals indicative of the glare-causing light levels.