Abstract: In a data communication system having a network composed of a central facility, a plurality of relay units, and a plurality of terminal units, traffic information, which may contain information about a number of calls and a total amount of communication time occurred with respect to each relay unit over the predetermined interval, is sent from the relay units to a communication control unit. A ROM stores a threshold value for each relay unit and comparison is made to compare the received traffic information with the corresponding threshold value. Then, the is determined whether the subject relay unit is in a high-load condition. If so, relay units and terminal units that are scheduled to call the high-load relay unit are detected so that those units bypass the high-load relay unit.

Abstract: The memory device 13 in the center 3 stores a plurality of information data categorized in a plurality of genres. The input device 43 of the terminal 5 selects an information data desired to be obtained, out of the plurality of information data stored in the memory device 13. The control portion 41 in the terminal 5 receives the desired information data and reproduces the desired information, when the desired information data is of a genre the terminal is contracted for. The control portion 41 does not reproduce the desired information or reproduces the desired information in a manner so that the user may not obtain when the desired information data is out of the genre the terminal is contracted for.

Abstract: A microcomputer selects one of a plurality of drive units, and controls the selected drive unit to reproduce image data from a video disk located thereon. When a reproduction error occurs in the thus reproducing drive unit, the microcomputer selects another drive unit, and controls the drive unit to reproduce images. Accordingly, it is possible to always provide accurate images.

Abstract: When a song data group of a requested song comes in the normal mode ("Yes" in S230, ) the terminal 5 picks up that song data D5 in S240. When the song data group of the requested song does not arrive ("No" in S230,) the terminal first judges in S250 whether or not it is necessary to rapidly obtain the song data of the requested song. If the terminal is presently playing a karaoke performance, it is unnecessary to rapidly obtain the song data of the requested song, and therefore the terminal waits for the song data that will come in the normal mode. If the terminal is not conducting a karaoke performance (i.e., "No" in S250), the terminal should be rapidly supplied with the requested song. When it is determined that the requested song will come soon ("Yes" in S290 or S300,) the terminal still waits for the song data that will come in the normal mode.

Abstract: A compact image karaoke device with only a small number of image disks which provides the impression of having a great many background images. Two players are provided for reading background images from image disks. Background images are selected from at least one image unit group corresponding to at least one image genre corresponding to selected song genre and are read by the two players and changed at random, for example, every 30 seconds. By editing the display of background images in this manner, a great number of background image series can be obtained for combinations of the background images. Images obtained and displayed corresponding particularly to the starting portion of the song are provided only on the number of images available. Therefore, even if a great number of songs are consecutively selected, a user will not feel as though the same images are being repeatedly shown.

Abstract: The clock demodulator 25 continually demodulates the clock signal of the control CPU 7 transmitted from the clock modulator 10 of the center S. The terminal control CPU 23 performs processes such as transmission and reception of data with the demodulated clock signal as a reference clock. The time required to synchronize the clocks of the CPUs 7 and 23 is eliminated. Transmission and reception of data is executed quickly as soon as right of transmission is transferred to a terminal.

Abstract: When images of the image genre most suitable for the selected song are being reproduced (Yes in S14), the karaoke terminal picks up those image data from a channel over which they are transmitted. If images of that image genre are not being reproduced (No in S14), when the number of players presently playing is less than four (No in S19), a player that is not presently playing starts playing a video disk to reproduce images of that image genre in S20. When the number of players presently playing is equal to or greater than four, according to the image genre D and/or H reproducing status, a player that is not presently playing starts playing a video disk to reproduce images of image genre D or H that includes or is common to the most suitable image genre.

Abstract: In a data transmission system, a center and a plurality of terminals are connected by a coaxial cable. The center is controlled by a server to transmit mode sense polling signals in succession every predetermined time (for example every 30 seconds) to all of the karaoke terminals connected to the center. The center determines whether each terminal is in a karaoke mode or not based on the mode response signal transmitted from each terminal in response to the mode sense polling signals. The center then transmits request polling signal only to terminals determined as being in the karaoke mode, confirms whether a request for a song has been made, and transmits karaoke data to those terminals that have a request.

Abstract: Interpolating processes for vertically aligned horizontal scanning lines are performed with respect only to red component video data so as to simplify the structure of an image processor and to decrease the number of components that are required for interpolation. Interpolation is always performed for the green component video data, which makes up a great deal of the luminance component. Even when only green is interpolated, 59% of the total luminance component of yellow is interpolated so that flicker is reduced to a practical level.