Abstract: Recording and playback of images and music independently of each other is made possible. To achieve this, it is so arranged that still-picture files, moving-picture files and music files can be recorded on a memory card. If a file selected from among files read out of the memory card is a still-picture file or a moving-picture file, an image represented by the read file is displayed on a liquid crystal display device and supply of voltage to circuits for music playback is cut off. If a selected file is a music file, then supply of voltage to circuits for image playback is cut off and music is played back.

Abstract: An information providing device assisting the users who meet each other accidentally in forming a community includes a user database (306) managing user information, an information database (307, 309, 310) managing information to be provided to a user, a database management unit (301) for managing information stored in the user database (306) and the information database (307, 309, 310), an information-receiver deciding unit (302) deciding a user who receives information stored in the information database (307, 309, 310) from the user information registered in the user database (306) in accordance with a prescribed condition and providing the user with an access right to information, and an access control unit (303) receiving access from the user and dynamically constructing a page to be displayed for the access based on the information database (307, 309, 310).

Abstract: A data search method capable of representing a complex search condition with a reduced number of filters and allowing high data visibility is used in a data search system including a storage disposed to store a plurality of data to be administered and attribute values associated with a desired number of attributes and respectively assigned to the plurality of data, a display, an input unit receiving an instruction from a user to perform an operation through a user operation to be performed on an object displayed on the display, and a data operation unit performing an operation on the plurality of data in response to the instruction received by the input unit.

Abstract: Recording and playback of images and music independently of each other is made possible. To achieve this, it is so arranged that still-picture files, moving-picture files and music files can be recorded on a memory card. If a file selected from among files read out of the memory card is a still-picture file or a moving-picture file, an image represented by the read file is displayed on a liquid crystal display device and supply of voltage to circuits for music playback is cut off. If a selected file is a music file, then supply of voltage to circuits for image playback is cut off and music is played back.

Abstract: A data management method of obtaining accurately the number of data satisfying a retrieval condition and the number of data not satisfying a retrieval condition is employed in a data management apparatus including: a storage device storing a plurality of data, each data having an attribute and an attribute value associated with each attribute; a display device; a control circuit for displaying on the display device a region for each attribute value of a certain attribute and a plurality of icons representing the plurality of data, respectively, on each region; and a circuit to retrieve data by a filter to which an attribute and an attribute value are related.

Abstract: A data communication device for data communication through radio among a plurality of devices includes a reception circuit receiving data, a storage circuit connected to the reception circuit to store received data, a transmission circuit connected to the storage circuit to search for one data communication device capable of communication therewith, and transmitting the data stored in the storage circuit into the found data communication device, and a control unit connected to the storage circuit, controlling the storage circuit to delete the data transmitted to the found data communication device in response to receiving reception complete data representing reception of data from the found data communication device.

Abstract: A device for protecting a secondary battery from overcharge and overdischarge has two switches and two diodes respectively connected in parallel with the switches. Each diode is conductive in the same direction as a parasitic diode included in the associated switch. When one of the switches is turned off, a current flows through the diode connected to the switch prior to the parasitic diode of the switch. This prevents a current from flowing through the switch in the opposite direction. The switches are, therefore, free from deterioration and damage and allow the protection device to surely operate without being damaged. Alternatively, a charge path and a discharge path may be connected in parallel with each other, and each may have a serial connection of a switch and a diode opposite in direction to a parasitic diode included in the switch.

Abstract: A recording/reproduction device uses a PG signal, generated in a yoke in accordance with rotation of a magnetic disc using a PG yoke, as a timing signal for recording or reproduction of video signals. A noise other than the PG signal is removed therefrom by rejecting a signal unless a signal status of "H" or "L" continues for a predetermined period of time or more. Also, a signal generated with a period shorter than that of the PG signal generated by one full turn of the magnetic disc is masked.

Abstract: Where T.sub.1 is a period of a dynamic operation range of a phase comparative waveform of a motor servo apparatus, and a period T.sub.0 of a reference phase signal is measured, the reference phase signal is delayed by T.sub.3 =T.sub.0 -T.sub.1 /2 to obtain a gate signal. The dynamic operation range is started by the gate signal. Thus, the operational center of the phase system is brought in line with the dynamic operation range. The operation is made symmetrical in the dynamic operation range to achieve a rapid servo lock and a stable phase control over the motor servo apparatus, even at the start of the motor or when an external perturbation occurs.

Abstract: A motor speed controller implements a speed control to phase control switch over. When the switch over occurs on initial offset between the reference speed signal phase and the current motor position phase is determined. The reference speed signal is then offset by this phase difference thereby achieving a quicker servo lock.

Abstract: A magnetic recording apparatus includes a control circuit and a switch which is provided between a recording amplifier and a secondary coil of a transformer for coupling the recording amplifier with a magnetic head, the control circuit stops a flow of a transient current into the magnetic head by controlling an ON/OFF timing of the switch.

Abstract: A still picture recording device is provided which uses a PG signal, generated in a yoke in accordance with the rotation of a magnetic disc using a PG yoke, as a timing signal for recording video signals. A second PG signal is produced from a first signal obtained by waveform-shaping a detection signal of the PG sensor. The recording of a video signal is initiated in response to the first PG signal, and the recording of the video signal on a recording track is completed responsive to the second PG signal.

Abstract: A resistor is provided in parallel with the capacitor of a phase compensating circuit in order that a rapid transition may be made to a steady velocity state when a motor is started, a target velocity (reference velocity) is changed, or a large fluctuation in load occurs. When the steady velocity state does not prevail, the capacitor is isolated from the circuit and the resistor is connected into the circuit in its place.