Patent ID: 6043810
Filing Date: 2000-03-28
Classification: G06F

Abstract:
A digitizer controller (100) for applying a 4-channel driving signal for driving the four corners of a panel (200) in response to a panel driving control signal befitting a stylus type and a touch panel type digitizer and outputting coordinate data by recognizing a contact position by a stylus or a finger, said digitizer controller comprising:a panel drive signal generator (10) for receiving a clock signal having a predetermined first frequency and generating a panel drive signal having a predetermined second frequency and required in stylus and finger touch modes;a 4-channel driving portion (16) for receiving said panel drive signal provided from said panel drive signal generator (10) and generating a channel driving signal which is provided to each corner of said panel (200) in response to said panel driving control signal according to an operation mode;a current-voltage converter (18) for detecting a change in current in or out of each corner of said panel (200);a differential amplifier (20) for generating a differential signal of four channels corresponding to a differential component between the output of said current-voltage converter (18) and the channel driving signal provided from said 4-channel driving portion (16) in said finger touch mode;a second multiplexer (22) for sequentially selecting the four-channel differential signal of the output from said differential amplifier (20) to output the selected signal as a finger touch signal;a third multiplexer (26) for selectively outputting one of the finger touch signal output from said second multiplexer (22) and a stylus signal output from a stylus in response to a mode selection signal indicating the stylus or the finger touch mode;a fourth multiplexer (34) for selectively outputting one of a predetermined second reference voltage and the touch panel signal output from said panel (200) in response to the mode selection signal;a band pass filter (28) for filtering the frequency component of the panel drive signal from the output of said third multiplexer (26);a rectifier (30) for rectifying the output of said band pass filter (28);a fifth multiplexer (36) for selectively outputting one of the outputs of said rectifier 30 and said fourth multiplexer (34) in response to the mode selection signal;a low pass filter (38) for detecting a substantial direct current component from the output of said fifth multiplexer (36);an analog-to-digital converter (44) for converting the output of said low pass filter (38) into a digital signal in synchronization with the panel driving control signal to output as a coordinates signal; andan interface (46) for receiving control commands provided from a microprocessor, generating the mode selection signal indicating the stylus, the finger touch or the touch panel mode by interpreting the received control command and the panel driving control signal corresponding to the selected mode, and transmitting the coordinates signal provided from said analog-to-digital converter 44 to the microprocessor.