DIGITAL KEYPAD

Brand	Owner	Address	Description
ENTRYCHECK	Security Door Controls	801 AVENIDA ACASO Camarillo CA 93012	Digital keypad, radio frequency identification (RFID) card reader, and biometric reader access control systems, namely, electronic door locks, keyless entry units, and biometric reader access control units for door security;ENTRY CHECK;
	Where the owner name is not linked, that owner no longer owns the brand

Technical Examples

The keypad interface element of this invention uses a relaxation oscillator and a digital keypad processor having a counter/timer to decode specific keys. The RC portion of the relaxation oscillator includes a resistance ladder and a set of momentary on pushbutton switches disposed change resistance dependent upon which key is pressed. This causes the relaxation oscillator to produce an output signal having a corresponding frequency. The counter/timer of the digital keypad processor produces a count corresponding to the oscillator frequency. The digital keypad processor latches and holds a binary number specifically identifying the depressed key. A state machine in the digital keypad processor provides transient-free, noise immune keypad decoding.