Display for automatic rearview mirror

An interior rearview mirror system for a vehicle comprising:

• a compass mirror reflective element including a reflectance surface and an electrochromic variable light transmission element;
• said reflectance surface having a portion that is at least partially light transmitting;
• a drive circuit for supplying a drive signal to said reflective element in order to establish the light transmission level of said light transmission element;
• a vacuum fluorescent display device behind said reflectance element that produces a compass display having an intensity level, wherein the intensity level of said compass display is variable by varying the duty cycle of a blanking signal applied to said display device;
• said display device being juxtaposed with said at least partially transmitting portion of said reflectance surface and adapted to be viewed through said light transmission element and said at least partially transmitting portion of said reflectance surface;
• a forward facing light sensor that senses light forward of the vehicle and a rearward facing light sensor that senses glare light conditions rearward of the vehicle;
• and
• said forward facing sensor and said rearward facing sensor providing input to said drive circuit so that when said forward facing sensor senses low light conditions in the vicinity of the vehicle, the light transmission level of said light transmission element is reduced in response to glare light conditions sensed by said rearward facing sensor and wherein the intensity level of said compass display of said display device increases to compensate for the reduced light transmission of said light transmission element.

A rearview mirror system for a vehicle comprising:

• a mirror reflective element including a reflectance surface and an electrochromic variable light transmission element;
• said mirror reflectance element being one of a compass mirror and an information mirror;
• said mirror reflectance surface having a portion that is at least partially light transmitting;
• a drive circuit for supplying a drive signal to said reflective element in order to establish the light transmission level of said light transmission element;
• a display device behind said reflective element that produces an alphanumerical display having an intensity level wherein the intensity level of said alphanumerical display is variable by varying the duty cycle of a blanking signal applied to said display device;
• said display device being juxtaposed with said at least partially transmitting portion of said reflectance surface and adapted to be viewed through said light transmission element and said at least partially transmitting portion of said reflectance surface;
• and
• a display control for supplying to said display device a pulse-width modulated blanking signal, said display control including a multiple slope oscillator that is adapted to produces a signal having one of a rising waveform and a falling waveform that has multiple-slope values.