Electronic control system for automatic rearview mirrors for automotive vehicles
First Claim
1. A control system for an automatic rearview mirror for an automotive vehicle, said automatic rearview mirror including a reflective element having a full reflectance mode and a partial reflectance mode, forward facing sensor means effective to detect light forwardly of the vehicle and generate a corresponding forward electrical signal indicative of the forward light level, backward facing sensor means effective to detect light rearwardly of the vehicle and generate a corresponding rearward electrical signal indicative of the rearward light level, forward sensor filtering means characterized by having a first time response and having a smoothing time averaging effect on the forward electrical signal and acting on the forward electrical signal to produce a filtered forward electrical signal independent of the rearward electrical signal, a rearward circuit having an input connected to said backward facing sensor means and an output, means operable to change said reflective element between said full reflectance mode and said partial reflectance mode as a function of the output of said rearward circuit and the filtered forward electrical signal, the functional time response provided by said forward facing sensor filtering means being slower than the functional time response provided by said rearward circuit, and means effective to reduce the sensitivity of the mirror as a function of the recent activity of said reflective element.
1 Assignment
0 Petitions
Accused Products
Abstract
An electronic control system for automatic rearview mirrors for automotive vehicles, the control system being effective to detect and compare the relative brightness of light forwardly and rearwardly of the vehicle and respond automatically to annoying glare from the rear of the vehicle and move a reflective element from a full reflective mode to a partial reflective mode and thereafter automatically return the reflective element to a full reflective mode after the source of the annoying glare is removed, the glare threshhold being determined as a function of the ambient light level, of a long, smoothed time average of the ambient light level, of a short smoothed time average of the glare producing light level, and of the recent activity of the mirror.
323 Citations
18 Claims
- 1. A control system for an automatic rearview mirror for an automotive vehicle, said automatic rearview mirror including a reflective element having a full reflectance mode and a partial reflectance mode, forward facing sensor means effective to detect light forwardly of the vehicle and generate a corresponding forward electrical signal indicative of the forward light level, backward facing sensor means effective to detect light rearwardly of the vehicle and generate a corresponding rearward electrical signal indicative of the rearward light level, forward sensor filtering means characterized by having a first time response and having a smoothing time averaging effect on the forward electrical signal and acting on the forward electrical signal to produce a filtered forward electrical signal independent of the rearward electrical signal, a rearward circuit having an input connected to said backward facing sensor means and an output, means operable to change said reflective element between said full reflectance mode and said partial reflectance mode as a function of the output of said rearward circuit and the filtered forward electrical signal, the functional time response provided by said forward facing sensor filtering means being slower than the functional time response provided by said rearward circuit, and means effective to reduce the sensitivity of the mirror as a function of the recent activity of said reflective element.
- 11. A control system for an automatic rearview mirror for an automotive vehicle, said rearview mirror including a reflective element having a full reflectance mode and a partial reflectance mode, said control system including first sensor means effective to detect light forwardly of the vehicle and generate a corresponding forward electrical signal indicative of the forward light level, second sensor means effective to detect light rearwardly of the vehicle and generate a corresponding rearward electrical signal indicative of the rearward light level, forward sensor filtering means characterized by having a first time response and having a smoothing time averaging effect on the forward electrical signal and acting on the forward electrical signal to produce a filtered forward electrical signal independent of the rearward electrical signal, a rearward circuit having an input connected to said second sensor means and an output, comparator means comparing the output of said rearward circuit and the filtered forward electrical signal, unidirectional, rotatable DC motor means operable to move said reflective element between said full reflectance mode and said partial reflectance mode, means controlling the energization of said motor means and controlled by said comparator means whereby said reflective element may be moved between its full reflectance mode and its partial reflectance mode as a function of the output of said rearward circuit and the filtered forward electrical signal, the functional time response provided by said forward sensor filtering means being slower than the functional time response provided by said rearward circuit, and means effective to reduce the activity of said reflective element as a function of the recent activity of said reflective element.
- 16. A control system for an automatic rearview mirror for an automotive vehicle, said rearview mirror including a reflective element having a full reflectance mode and a partial reflectance mode, said control system including first sensor means effective to detect light forwardly of the vehicle and generate a corresponding forward electrical signal indicative of the forward light level, second sensor means effective to detect light rearwardly of the vehicle and generate a corresponding rearward electrical signal indicative of the rearward light level, forward sensor filtering means including a capacitor and characterized by having a first time response and having a smoothing time averaging effect on the forward electrical signal and acting on the forward electrical signal to produce a filtered forward electrical signal independent of the rearward electrical signal, a rearward circuit having an input connected to said second sensor means and an output, comparator means comparing the output of said rearward circuit and the filtered forward electrical signal, unidirectional, rotatable DC motor means operable to move said reflective element between said full reflectance mode and said partial reflectance mode, means controlling the energization of said DC motor means and controlled by said comparator means whereby said reflective element may be moved between its full reflectance mode and its partial reflectance mode as a function of the output of said rearward circuit and the filtered forward electrical signal, the functional time response provided by said forward sensor filtering means being slower than the functional time response provided by said rearward circuit, and means effective to reduce the charge on said capacitor during each return of said reflective element to its fully reflective mode and permitting said capacitor to thereafter recharge at a predetermined rate.
Specification