Rohm Co., Ltd.

Haruo Taguchi

Yoshihiro Ikefuji

Junichi Hikita

Takashi Naiki

Shigemi Chimura

Hidekazu Kojima

In a negative step-up charge pump circuit according to the present invention, of a plurality of stages of charge transfer transistors and an output transistor, the former-stage transistors are P channel type field effect transistors, and the later-stage transistors are N channel type field effect transistors. With such configuration, it is possible to avoid start-up failure and current driving performance deterioration resulting from an increase in the number of stages of step-up units without complicating processes and increasing the chip size.

Negative step-up charge pump circuit, LCD driver IC, and liquid crystal display device

The invention provides a display apparatus having a temperature sensor and a step-up circuit generating a drive voltage of the display apparatus by stepping up a power source voltage. The temperature sensor provides temperature data indicative of the temperature of the display panel with a reduced measurement error without limiting the operation of the step-up circuit. To do so, in view of the fact that the step-up circuit has alternating active state in which the circuit is stepping up a source voltage to output a required step-up voltage and inactive state in which no stepping operation is made, the temperature sensor is adapted to obtain temperature data while the step-up circuit is inactive. The temperature data obtained is supplied to a temperature compensation means for changing the drive condition setting value that define the drive condition of the display panel to compensate for the temperature change.

Display apparatus having temperature compensation function

An IC card has an ID number ID , for permitting itself to be identified, stored in memory provided therein. The IC card also has additional ID numbers ID to IDn stored in memory areas - to - that are secured therein so as to be allocated to the individual providers that manage the reader/writers with which the IC card communicates. These additional ID numbers ID to IDn are used to prevent unauthorized use of the IC card, and are issued so as to be unique to the IC card by the individual providers that use the memory areas - to - . Thus, the additional ID numbers ID to IDn differ from one IC card to another.

Data communication transponder and communications system employing it

In a communications system having an authentication function, a relaying apparatus is used. This relaying apparatus has an authentication circuit for checking whether reader/writers - to -n are authentic or not by detecting whether or not the authentication signals from the reader/writers - to -n have been subjected to a predetermined calculation operation within the reader/writers - to -n, a multiplexer for switching the lines connecting between the reader/writers - to -n and, a PC in accordance with the results of the authentication processes performed by the authentication circuit , and a calculation circuit for performing a predetermined calculation operation on the authentication signals from the reader/writers - to -n and for feeding them back to the reader/writers - to -n.

Communications system having an authentication function

A memory ( ) in a non contact type IC card ( ) includes a data protection region (B ) storing data requiring security and an region (B ) storing other data. A main control circuit ( ) generates data to be stored and designates a location for data storage in the region (B ) or the data protection region (B ) according to a content of the data. An address non selecting circuit ( ) selects whether the generated data is to be written into the location in the data protection region (B ) designated by the main control circuit ( ) according to a state of a state setting circuit ( ).

Non contact type IC card

A data communication apparatus according to the present invention can be used both in one-wave mode and two-wave mode, and includes: first and second tuning circuits ( ); a power supply circuit ( ) connected to first tuning circuit ( ) for generating power by a signal received by first tuning circuit ( ); an information processing circuit ( ) connected to first tuning circuit ( ) or second tuning circuit ( ) through a switching circuit ( ) and including a detection circuit ( ), a decoder ( ), an encoder ( ) and the like. Information processing circuit ( ) includes a switch control circuit ( ) detecting if the mode of the received radio wave is one-wave mode or two-wave mode in accordance with an output from first tuning circuit ( ) and controlling switching circuit ( ) such that detection circuit ( ) is connected to one of first and second tuning circuits ( ).

Growing community of inventors

Kyoto, Japan

Haruo Taguchi