Input device and method for detecting switch of input device
View Patent ↗An input device includes a resistor group, an input terminal, a plurality of switches, and a control unit. The resistor group includes a plurality of resistors connected in series. The input terminal is connected to one end of the resistor group. Each switch of the plurality of switches has one end connected to each resistor of the plurality of resistors at an opposite side viewed from the input terminal and the other end grounded. The control unit detects an applied voltage to the input terminal when the plurality of switches are all turned off. Furthermore, the control unit detects an output voltage from the input terminal when any of the plurality of switches is turned on, and detects a switch that is turned on among the plurality of switches based on a voltage ratio of the output voltage to the applied voltage.
1. An input device comprising:
a resistor group including a plurality of resistors connected in series;
an input terminal connected to a power supply via a resistor having a predetermined value and connected to one end of the resistor group;
a plurality of switches each having one end connected to each resistor of the plurality of resistors at an opposite side viewed from the input terminal, and an other end grounded; and
a control unit connected to the input terminal,
wherein the control unit is configured to previously store resistance ratios of each of resistance between the input terminal and ground, to sum of the resistor with the predetermined value and the each of resistances between the input terminal and the ground when each of the plurality of switches is turned on, and
wherein the control unit is configured to detect an applied voltage to the input terminal when the plurality of switches are all turned off, and to detect an output voltage from the input terminal when any one of the plurality of switches is turned on, and determines the switch that is turned on by collating a voltage ratio of the output voltage to the detected applied voltage with the stored resistance ratios.
2. A method for detecting a switch of an input device, the input device including:
a resistor group including a plurality of resistors connected in series;
an input terminal connected to a power supply via a resistor having a predetermined value and connected to one end of the resistor group;
a plurality of switches each having one end connected to each resistor of the plurality of resistors at an opposite side viewed from the input terminal, and an other end grounded; and
a control unit connected to the input terminal, the control unit configured to previously store resistance ratios of each of resistance between the input terminal and ground, to sum of the resistor with the predetermined value and the each of resistances between the input terminal and the ground when each of the plurality of switches is turned on, and
the method comprising:
detecting an applied voltage to the input terminal when the plurality of switches are all turned off;
detecting an output voltage from the input terminal when any one of the plurality of switches is turned on; and
determining the switch that is turned on by collating a voltage ratio of the output voltage to the detected applied voltage with the stored resistance ratios.