Abstract: An IC card capable of accumulating the degree of shoppers' interest in a commodity is provided. For this purpose, the IC card has a front surface provided with a display for displaying information of the commodity. The displayed contrast thereof can be changed continuously or progressively in stages by shopper's touch to a sensor. The characters of the display are normally light, and therefore the shopper must touch the sensor to increase the contrast of the display in order to obtain more information of the commodity he/she is interested in. As a result, the shopper touches the sensor of the IC card attached to the commodity he/she is interested in. The number of times shoppers touch the commodity is counted by a counter, so that the degree of shoppers' interest in the commodity can be grasped quantitatively.

Abstract: A plurality of light-receiving devices dispersed over the area of an IC chip operate in response to the opening of an IC device such that switching transistors are turned on or off to prohibit the normal operation of logic circuits or logic elements, thereby securing protection against normal reading of the internal data of the opened IC device, particularly against the analysis of the IC's internal logic with an electron beam tester.