Abstract: A flat acoustic conversion device includes two magnets disposed so that their magnetic poles face upward arid are adjacent to or in contact with one another, and the magnetic pole faces of different polarities arc disposed alternately; a vibrating member disposed on the top surface of the yoke; coil pairs wound in helical form and disposed at front and reverse surfaces of the vibrating membrane; such that magnetic flux traveling in a direction substantially parallel to a surface of the vibrating membrane becomes a maximum, and interlinks with the coil pairs. When current is supplied to the coils, a direction of force which the current receives from a magnetic field is substantially orthogonal to the surface of the vibrating membrane, and force in a direction along the surface of the vibrating membrane becomes extremely low. Thus, noise components can be reduced such that sound quality can be improved.

Abstract: This invention provides a planar acoustic converting apparatus including a support having a flat plate portion, a diaphragm which has an insulating base film having a liquid crystalline polymer film and being opposed to the flat plate portion of the support and at least one spiral coil provided on one major surface or both major surfaces of the insulating base film, at least one permanent magnet supported by the support and opposing a magnetic pole to the diaphragm, and a holding portion provided to the support and holding the diaphragm such that the diaphragm can vibrate and is positioned apart from the at least one permanent magnet.

Abstract: Permanent magnets m18, m28 and m38 each of which is formed in a flat and rectangular shape are disposed on a yoke 20 with the magnetic pole surfaces facing upwardly so that the magnetic pole surfaces whose polarities are different are disposed alternately. A vibrating diaphragm 26 is disposed on the top surface of the yoke 20 so as to be in parallel with the magnetic pole surfaces of the permanent magnets. Pairs of coils L18, L28 and L38 which are wound in a swirled shape and are disposed at the top and rear surfaces of the vibrating diaphragm are disposed on the vibrating diaphragm 26 so as to correspond to the permanent magnets m28 and m38, respectively. Each of the pairs of coils L18, L28 and L38 is wound in a swirled shape so as to be substantially analogous with the external edge of the magnetic pole surface of each of the permanent magnets m18, m28 and m38.

Abstract: A data acquisition system senses current and voltage from a common electrical circuit supplying a power to load branch circuits containing loads that undergo changes in load condition, such as starting and stopping. Transmitters connected to the load branch circuits identify the loads that undergo load condition changes. A data processor receives information from both the sensors and the transmitters to link the sensed current and voltage information from the common electrical circuit to the particular loads that undergo changes in load condition.

Abstract: Directional control valves are arranged with restrictable center passageways connected in series to a fixed displacement pump and with restrictable power and exhaust passageways straddling loads connected in parallel to the same fixed displacement pump. Pressure responsive valves located between the loads and the restrictable exhaust passageways reduce interactions between the loads. Another pressure responsive valve located between the fixed displacement pump and the restrictable center passageways maintains an appropriate division of flow between the restrictable center passageways and the restrictable power and exhaust passageways.