Patents by Inventor Phillip J. McKenzie

Phillip J. McKenzie has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Constant brightness liquid crystal display backlight control system
    Patent number: 5272327
    Abstract: A LCD backlight system which regulates the light generated by the lamp by controlling the intensity of the light using a photoresistor cell. The current provided to the lamp is controlled by a pulse width modulation (PWM) signal. The PWM signal responds to brightness adjustments by the user and to a photoresistor exposed to the light from the lamp. An operational amplifier circuit controls the PWM signal so that if the lamp is too bright, the current to the lamp is reduced, and if the lamp is too dim, the current to the lamp is increased. When the lamp brightness reaches the appropriate intensity, the output of the operational amplifier is unchanging, causing the intensity of the lamp to remain stable.
    Type: Grant
    Filed: May 26, 1992
    Date of Patent: December 21, 1993
    Assignee: Compaq Computer Corporation
    Inventors: Nathan A. Mitchell, Phillip J. McKenzie