Abstract: A dry turbo vacuum pump has a multistage circumferential impeller supported on a shaft, and a stator which cooperates with it to form a multistage peripheral flow pump. A centrifugal pump arranged at an inlet side of the peripheral flow pump is also mounted on the same shaft, so that gas sucked from the inlet is discharged to the atmosphere from the peripheral flow pump. The multistage peripheral flow pump and at least one stage of the centrifugal pump are integrated.

Abstract: A two-way transmitting apparatus which transmits display data and audio signal from an audio reproducing device to a remote controller and headphones with display by wireless transmitting, and transmits control signals to the audio reproducing apparatus according to one of the operation of a plurality of operation unit established on the remote controller and the headphones. The control data is divided into a predetermined number of blocks, the discrimination code "d" is inserted between respective blocks to generate the data sequence, and the data length per unit block is set to most approximate to the value of square root of the control data length.

Abstract: A turbo vacuum pump for compressing a low-pressure gas to discharge the compressed gas into atmosphere comprises pump stator having a gas flow passage comprising a plurality of annular flow passages on an inner surface thereof arranged stepwise diameters of which become smaller toward downstream and passages intercommunicating with adjacent annular flow passages and a gas discharge port communicated with one of the plurality of annular flow passages disposed at the most downstream. The pump stator includes a cylindrical spiral grooved pump impeller and a plurality of peripheral flow pump impellers facing the annular flow passages provided downstream of the cylindrical spiral grooved pump impeller and having stepwise diameters which become smaller toward downstream to form a peripheral flow pump stage.