Abstract: A thermal poling method in which a poling treatment can be performed easily by a dry process. The poling treatment is performed on a PZT film by performing a heat treatment on the PZT film under a pressurized oxygen atmosphere at a temperature of 400° C. or more and 900° C. or less. The PZT film before the heat treatment has a single-domain crystal structure, and the PZT film after the heat treatment has a multi-domain crystal structure.

Abstract: A thermal poling method in which a poling treatment can be performed easily by a dry process. The poling treatment is performed on a PZT film by performing a heat treatment on the PZT film under a pressurized oxygen atmosphere at a temperature of 400° C. or more and 900° C. or less. The PZT film before the heat treatment has a single-domain crystal structure, and the PZT film after the heat treatment has a multi-domain crystal structure.

Abstract: A thermal poling method in which a poling treatment can be performed easily by a dry process. The poling treatment is performed on a PZT film by performing a heat treatment on the PZT film under a pressurized oxygen atmosphere at a temperature of 400° C. or more and 900° C. or less. The PZT film before the heat treatment has a single-domain crystal structure, and the PZT film after the heat treatment has a multi-domain crystal structure.

Abstract: Even when the total length of a display device is increased, the strength of a case is sufficiently ensured without increasing the total length of the case itself.

Abstract: Disclosed is a portable terminal device, which has a reduced thickness, while ensuring a strength with which a display unit can be excellently held. In the device (100), the flat-board-like display unit (200) provided with a display drive section (213) that drives a liquid crystal display section (211) is attached to a first case (110) with a metal rear plate (160) therebetween. The rear plate (160) is provided with a reinforcing section (180), which is formed by folding back one plate end portion, which has a predetermined width, a plurality of times into a roll-shape on the rear surface side of the rear plate (160). The reinforcing section (180) is disposed at a position that includes the horizontal projection area of the display drive section (213), and prevents stress from concentrating on the display drive section (213) by reinforcing the display drive section (213).