Abstract: A branching system having an optical ADM, where the optical ADM comprises a first optical circulator being connected to a main signal transmission line input, a first FBG having an input which is an output of the first optical circulator, an optical isolator having an input which is an output of the first FBG, a second optical FBG having an input which is an output of the optical isolator and a second optical circulator having an input which is an output of the second FBG. With this structure, the optical amplifier is able to detect whether the branch transmission line is being cut off due to obstructions. Thus, even if a detour route of light being branched off at the optical circulator is generated, for the light is intercepted by the optical isolator, there should be no generation of a loop. Thus, deterioration on the transmission feature of the main transmission line can be prevented.

Abstract: Diodes are connected between a clamp control line and respective one of data lines. A voltage of the clamp control line in a read operation is set to a value higher, by a forward voltage of the diodes or less, than a lower value among the voltages of the data line to which a selected digit line is connected. The voltages of the data lines to which only non-selected digit lines are connected are clamped to a predetermined value.

Abstract: An audio output circuit in an electronic apparatus equipped with a composite display function where a plurality of pictures can be displayed on composite screen regions of a single display screen. The circuit includes an audio signal switching circuit for selectively switching audio signals relative to the pictures displayed on the individual screen regions and outputting the selected audio signal to a speaker. The circuit also includes a simultaneous audio output switching circuit for selecting a plurality of audio signals out of those relative to the pictures displayed on the individual screen regions and then outputting the selected audio signals simultaneously through a plurality of speakers. Thus any audio signal(s) relative to the picture(s) displayed on the individual screen region(s) can be heard either selectively or simultaneously through the speaker(s).

Abstract: A packaging box is used for packaging frozen food with an improved heat-insulating property. The movement of air surrounded by a corrugated core of a conventional corrugated card-board is interrupted, thereby enhancing the heat-insulating property. The air is prevented from permeating through the corrugated property. Further in order to improve the heat-insulating property, laminated aluminum foil is used.