Combination touch and transducer input system and method
A combination touch and transducer input system is provided, which facilitates user input into an electronic system with a finger and/or a transducer (e.g., a stylus). The system includes a transducer configured to generate an electric field, and a sensor including an array of electrodes and a controller. The transducer is configured to transmit digital data, such as pen pressure data and switch status data, to the sensor. For example, the transducer comprises electronic circuitry configured to encode the digital data in a signal for transmission to the sensor. The sensor controller is configured to operate both in a touch sensing mode and in a transducer sensing mode. During the touch sensing mode, the controller determines a position of a proximate object (e.g., a finger) by capacitively sensing the object with the array of electrodes. During the transducer sensing mode, the controller determines a position of the transducer based on a signal received by the array of electrodes from the transducer, and also receives and decodes the digital data encoded in the received signal. Digital data can be encoded in a signal using any suitable digital modulation techniques, such as a Frequency-Shift Keying (FSK) technique.
1. A position input system, comprising:
an array of electrodes; and
a controller coupled to the array of electrodes and configured to:
when operating in a touch mode, determine a position of a proximate object by capacitively sensing the object with the array of electrodes, and
when operating in a transducer mode, determine a position of a transducer by measuring a sensing signal which is induced in the array of electrodes by a magnetic field component of an electromagnetic field generated by the transducer,
wherein:
one side of the array of electrodes are connected to a set of switches; and
the controller is configured to, in the transducer mode, control the set of switches to make the array of electrodes to form loop electrodes in which the sensing signal is electromagnetically induced.
2. The position input system of claim 1 , wherein:
the array of electrodes include a first electrode and a second electrode; and
the controller is configured to, in the transducer mode, control the set of switches to:
connect one end of the first electrode to the controller; and
connect one end of the second electrode to a reference voltage.
3. The position input system of claim 2 , wherein:
another end of the first electrode is connected by a trace to another end of the second electrode.
4. A position input system, comprising:
an array of electrodes, wherein
one ends of the electrodes are connected to each other by a trace; and
other ends of the electrodes are connected to a set of switches, and
a controller coupled to the array of electrodes and configured to control the set of switches to selectively form loop coils in which sensing signals are induced by a magnetic field component of an electromagnetic field generated by a transducer, wherein:
the array of electrodes include a first electrode and a second electrode which form a first loop coil; and
the controller is configured to control the set of switches to:
connect the first electrode to a detection section of the controller; and
connect the second electrode to a reference voltage.
5. The position input system of claim 4 , wherein:
the controller is configured to control the set of switches to:
leave electrodes of the array of electrodes, other than the first electrode and the second electrode, unconnected to either the detection section of the controller or to the reference voltage.
6. A method of controlling a position input system which includes an array of electrodes, the method comprising:
in a touch mode, determining a position of a proximate object by capacitively sensing the object with the array of electrodes, and
in a transducer mode, determining a position of a transducer by measuring a sensing signal which is induced in the array of electrodes by a magnetic field component of an electromagnetic field generated by the transducer, wherein:
one side of the array of electrodes are connected to a set of switches; and
the method comprises:
in the transducer mode, controlling the set of switches to make the array of electrodes to form loop electrodes in which the sensing signal is electromagnetically induced.
7. The method of claim 6 , wherein:
the array of electrodes include a first electrode and a second electrode; and
the method comprises, in the transducer mode, controlling the set of switches to:
connect one end of the first electrode to a detection controller; and
connect one end of the second electrode to a reference voltage.
8. The method of claim 7 , wherein:
another end of the first electrode is connected by a trace to another end of the second electrode.
9. A method of controlling a position input system which includes an array of electrodes, wherein one ends of the electrodes are connected to each other by a trace and other ends of the electrodes are connected to a set of switches, the method comprising:
controlling the set of switches to selectively form loop coils in which sensing signals are induced by a magnetic field component of an electromagnetic field generated by a transducer, wherein:
the array of electrodes include a first electrode and a second electrode which form a first loop coil; and
the method comprises controlling the set of switches to:
connect the first electrode to a detection controller; and
connect the second electrode to a reference voltage.
10. The method of claim 9 , comprising:
controlling the set of switches to:
leave electrodes of the array of electrodes, other than the first electrode and the second electrode, unconnected to either the detection controller or to the reference voltage.