Touch panel system, stylus pen, and electronic device
A touch panel system ( 1 ) according to one aspect of the invention includes: a stylus pen ( 15 ) including a drive circuit ( 26 ) that generates a first driving voltage based on a first code sequence and a second driving voltage based on a second code sequence, and a sensor circuit ( 40 ) that drives a pen point ( 38 ) with a multiplexed voltage obtained by multiplexing the first driving voltage and the second driving voltage; and a touch panel controller ( 2 ) that detects a position of the stylus pen ( 15 ) touching a touch panel.
1. A touch panel system, comprising:
a stylus pen for touching a touch panel which has M first signal lines (M is plural), K second signal lines (K is plural) which intersect with the M first signal lines, and (M×K) electrostatic capacitances formed at respective intersections of the first signal lines and the second signal lines; and
a touch panel controller that detects a position of the stylus pen, wherein
the touch panel controller includes a driver that applies a voltage on the M first signal lines based on first signal line code sequences indicative of M code sequences among (M+2) code sequences having a length of N (N is plural) and supplies the two remaining code sequences to the stylus pen, and
the stylus pen includes
a driving circuit which generates a first driving voltage based on a first code sequence indicating one of two remaining code sequences among the (M+2) code sequences having a length of N (N is plural) and a second driving voltage based on a second code sequence indicating another one of the two remaining code sequences, and
a multiplexing circuit which drives a pen point of the stylus pen with a multiplexed voltage obtained by multiplexing the first driving voltage and the second driving voltage, and
the multiplexing circuit has
a variable resistor one end of which is connected to a first terminal to which the first driving voltage is applied and whose resistance value changes based on information regarding the stylus pen,
a fixed resistor one end of which is connected to a second terminal to which the second driving voltage is applied, and
an output terminal which is connected to the other end of the fixed resistor and the other end of the variable resistor and which outputs the multiplexed voltage.
2. The touch panel system according to claim 1 , wherein the information regarding the stylus pen is information indicating a writing pressure applied to the pen point.
3. The touch panel system according to claim 2 , wherein
the touch panel controller includes:
a driver that drives the M first signal lines with a synchronization signal in a sense mode period and thereafter drives the M first signal lines based on a code sequence in a driving mode period to output a first linear sum signal based on charges, which are accumulated in the electrostatic capacitances, along the K second signal lines, and drives the K second signal lines with the synchronization signal in a next sense mode period and thereafter drives the K second signal lines based on the code sequence in a next driving mode period to output a second linear sum signal based on the charges, which are accumulated in the electrostatic capacitances, along the M first signal lines; and
position detection means that detects a position of a target, which has touched the touch panel, based on the first linear sum signal and the second linear sum signal, wherein
the stylus pen includes a synchronization circuit that receives the synchronization signal, and
the driving circuit generates the first driving voltage and the second driving voltage based on an output of the synchronization circuit.
4. The touch panel system according to claim 3 , wherein the driver drives the M first signal lines in parallel and drives the K second signal lines in parallel.
5. The touch panel system according to claim 1 , wherein the touch panel controller includes:
a driver that drives the M first signal lines with a synchronization signal in a sense mode period and thereafter drives the M first signal lines based on a code sequence in a driving mode period to output a first linear sum signal based on charges, which are accumulated in the electrostatic capacitances, along the K second signal lines, and drives the K second signal lines with the synchronization signal in a next sense mode period and thereafter drives the K second signal lines based on the code sequence in a next driving mode period to output a second linear sum signal based on the charges, which are accumulated in the electrostatic capacitances, along the M first signal lines; and
position detection means that detects a position of a target, which has touched the touch panel, based on the first linear sum signal and the second linear sum signal, wherein
the stylus pen includes a synchronization circuit that receives the synchronization signal, and
the driving circuit generates the first driving voltage and the second driving voltage based on an output of the synchronization circuit.
6. The touch panel system according to claim 5 , wherein the driver drives the M first signal lines in parallel and drives the K second signal lines in parallel.
7. A stylus pen for touching a touch panel which has M first signal lines (M is plural), K second signal lines (K is plural) which intersect with the M first signal lines, and (M×K) electrostatic capacitances formed at respective intersections of the first signal lines and the second signal lines, the touch panel having a touch panel controller that includes a driver that applies a voltage on the M first signal lines based on first signal line code sequences indicative of M code sequences among (M+2) code sequences having a length of N (N is plural) and supplies the two remaining code sequences to the stylus pen, the stylus pen comprising:
a driving circuit which generates a first driving voltage based on a first code sequence indicating one of two code sequences among (M+2) code sequences having a length of N (N is plural) received from the driver of the touch panel and a second driving voltage based on a second code sequence indicating another one of the two code sequences; and
a multiplexing circuit which drives a pen point of the stylus pen with a multiplexed voltage obtained by multiplexing the first driving voltage and the second driving voltage,
wherein the multiplexing circuit has
a variable resistor one end of which is connected to a first terminal to which the first driving voltage is applied and whose resistance value changes based on information regarding the stylus pen,
a fixed resistor one end of which is connected to a second terminal to which the second driving voltage is applied,
an output terminal which is connected to the other end of the fixed resistor and the other end of the variable resistor and which outputs the multiplexed voltage, and
a voltage being applied on the M first signal lines based on first signal line code sequences indicative of remaining M code sequences among the (M+2) code sequences, and the first code sequence indicative of one of the two code sequences among the (M+2) code sequences and the second code sequence indicative of another one of the two code sequences being supplied to the driving unit.
8. An electronic device comprising the touch panel system according to claim 1 .