Patent ID: 7225667

Claim:
A tire pressure gauge comprising: a body having a front end having an opening; a rear end having an opening; a sidewall; a battery compartment formed at the rear end and communicating with the opening in the rear end; and a valve stem connector mounted in the opening at the front end of the body and adapted to be pressed onto a valve stem of a tire to sample internal air pressure; a controller mounted inside the body and comprising a microprocessor having multiple input ports, multiple output ports and a preset pressure value stored in the microprocessor; a pressure sensor connected to the valve stem connector and one of the input ports of the microprocessor to sense air pressure inside a tire sampled by the valve stem connector, to generate an electronic signal indicating the sensed pressure and to output the electronic signal to the microprocessor for comparison to the preset pressure value; a pressure indicator mounted on the body, connected to one of the output ports of the microprocessor and driven by the microprocessor to indicate a tire's air pressure; an alarm unit connected to one of the output ports of the microprocessor and driven by the microprocessor to emit an audible warning when the air pressure in a tire sensed by the pressure sensor is below the preset pressure value in the microprocessor; a mode switch mounted on and protrudes through the body, connected to one of the input ports of the microprocessor and turning the tire pressure gauge on and off and changing the units of pressure displayed in the pressure indicator; and a power unit being at least one battery, mounted in the battery compartment and being connected to and supplying power to the microprocessor, the pressure sensor, the pressure indicator and the alarm unit; and a cap mounted detachably on the rear end of the body, closing the battery compartment and comprising a hollow housing having a closed outer end covering the opening in the rear end of the body and holding at least one battery in the battery compartment; and a sidewall; a pocket clip attached to the sidewall of the hollow housing; and a sidewall.