Sharp Kabushiki Kaisha Corporation

Kazumasa Kimura

Masato Hiramoto

Yoshio Okajima

Toshiyuki Ueda

Tazo Nishida

A touch panel input apparatus has a touch panel which consists of X- and Y-direction electrode panels. When the apparatus is in a power-off state, one end of the X electrode panel is intermittently connected to a power source and one end of the Y electrode panel is intermittently grounded via an output resistor, in response to control signals outputted from a sampling circuit. In this state, synchronously with a clock signal, the sampling circuit performs sampling of a voltage developed across the output resistor when the two electrode panels are brought into contact. The sampling circuit outputs a power-on instruction signal to make the CPU perform the power-on operation. The sampling circuit stops its sampling operation once power is turned on.

Touch panel input apparatus performing a sampling operation

A stored data protection apparatus for an electronic device has a CPU (20) and a volatile memory (21) controlled by the CPU for storing data therein. Both of the CPU and the volatile memory ace supplied power voltage from a main battery (22) in normal operation of the device. The volatile memory as supplied power voltage from a back-up battery (23) when the main battery is removed from the device. The apparatus has a switch (29) operable in first and second positions, taking the first position in the normal operation of the device, and being switched from the first position to the second position when the main battery is removed from the device, a circuit (44, 48) for inhibiting the CPU to access the volatile memory when the switch is in the second position, and a circuit (38, 34, 42, 43) for releasing the inhibition of the CPU by the inhibiting circuit when the switch is switched from the second position to the first position.

Back-up power supply apparatus for protection of stored data

An electronic apparatus is provided with a main battery, semiconductor memories having a chip select input (active low), a backup battery, a pull-up resistor, a control unit for selecting one of the semiconductor memories, and a selection control line connected between the control unit and the chip select input. The selection control line is connected to the backup battery through the pull-up resistor. A switch for closing or opening the selection control line is connected between the selection control unit and the junction point of the control line and the pull-up resistor. A switch control unit is provided which controls the switch to open the control line when the semiconductor memory is powered by the backup battery. In another electronic apparatus having a detection circuit for detecting the voltage of the backup battery, the switch is closed only when the voltage is to be monitored.

Growing community of inventors

Yamatokoriyama, Japan

Kazumasa Kimura