Patents by Inventor Mark P. C. Chen

Mark P. C. Chen 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).

  • Photo monitoring apparatus with visual/audio alarm
    Patent number: 5530432
    Abstract: A photo monitoring apparatus including a photoresistor, a series of shunt resistors, and a comparator IC, wherein the comparator IC provides an output signal to a LED and a diaphragm speaker, when the voltage from the shunt resistors drops below a pre-set reference voltage, causing the LED to give light and the diaphragm speaker to produce a warning sound. The shell of the photo monitoring apparatus is installed with a digital time display controlled by a time circuit to indicate time.
    Type: Grant
    Filed: February 3, 1995
    Date of Patent: June 25, 1996
    Inventor: Mark P. C. Chen