Ink maintained at a negative pressure state is supplied to an ink-jet recording head via an ink supply mechanism constructed as a differential pressure valve having a coil spring and a movable membrane normally contacted elastically with a valve seat by the coil spring. The length defines a central region disposed between first and second ends. A sealing material that softens with heat is applied to the peripheral region of at least one of the surfaces of the front and back substrates that are to face each other. , and thus the blend of polyvinylchloride with the polyetherekentone can be applied to high temperature end-use products such as hot water pipes. The unique pre-shared key is stored in association with information regarding the user device. The third level of circuitry may be electrically connected to the first level of circuitry through the interconnect.