US Patent No. 10,368,405

TWO STAGE INDICATOR DIMMING CIRCUIT CONTROLLED BY PWM BACKLIGHTING BACK FEED AND BACKLIGHT CONTROL


Patent No. 10,368,405
Issue Date July 30, 2019
Title Two Stage Indicator Dimming Circuit Controlled By Pwm Backlighting Back Feed And Backlight Control
Inventorship Michael Mashkevich, West Bloomfield, MI (US)
David A Lescamela, Macomb, MI (US)
James M Burcar, Rochester, MI (US)
Ron R Peteuil, Rochester Hills, MI (US)
Assignee FCA US LLC, Auburn Hills, MI (US)

Claim of US Patent No. 10,368,405

1. A dimming circuit for an indicator switch, the indicator switch including a manually actuated switch, an indicator LED that is not driven by an indicator PWM signal and is turned on and off by a function control module to which the indicator switch is coupled wherein the indicator LED is on when a function actuated by the manually actuated switch of the indicator switch is active and off when the function actuated by the manually actuated switch of the indicator switch is off, the dimming circuit comprising:a control input; and
the dimming circuit responsive to the presence of a backlight PWM signal at the control input of the dimming circuit to switch to a dimming state and responsive to the absence of the backlight PWM signal at the control input of the dimming circuit to switch to a non-dimming state, when the dimming circuit is in the dimming state a high resistance of the dimming circuit is statically connected in series with the indicator LED and a LED drive output of the function control module and when the dimming circuit is in the non-dimming state a low resistance of the dimming circuit is statically connected in series with the indicator LED and the LED drive output of the function control module, the high resistance having a resistance higher than the low resistance, wherein a light intensity of the indicator LED when the dimming circuit is in the non-dimming state is higher than when the dimming circuit is in the dimming state.