A circuit and method are presented for signal processing and routing of digital voice telephony signals, using a specialized high-density integrated circuit voice processor. The interfacing means 21 performs software interfacing under the control of a program while address decoders and input and output ports perform electrical interfacing. A partition plate partitioning an inside of the casing up and down is arranged in the casing, and a portion of the partition plate below the chip introducing port is configured to be openable and closable. The arrangement permits a volumetrically efficient operation while preventing excessive fatigue of the member. The analog circuit unit, the digital circuit unit, and the power circuit unit are formed on separate circuit boards, respectively, and the analog circuit unit and the digital circuit unit are arranged on the opposite side of the radiation detecting unit with respect to the support member. This method for cleaning a heat mode type recording material layer is applicable to a method for manufacturing a pit-projection product, a method for manufacturing a light emitting element, and a method for manufacturing an optical element.