This invention relates to a recording medium reproducing device which has a vibration-resisting function, such as a portable CD (compact disk) player and an automobile mount CD player.
A CD player mounted on an automobile (hereinafter referred to as "an automobile CD player", when applicable) is liable to be vibrated; that is, it suffers from so-called "sound skip (intermittent signal reproduction)" when the automobile is traveling. In order to overcome this difficulty, a CD player of this type has a vibration resisting function.
When a conventional mobile DC player having a vibration resisting function is operated, the spindle motor is rotated at a speed about twice as high as the standard reproduction speed of an ordinary CD player, while the pickup reads data from the CD, and the data thus read are stored in memory to a predetermined amount. Next, in the reproducing device, the micro-computer outputs the data at the standard reproduction speed of the CD player which have been stored in memory, and converts them into reproducing signals.
Hence, even in the case where the CD player is shocked or vibrated while the automobile is traveling, so that the pickup is shifted from the data track; that is, it cannot read data from the CD, the data which have been stored in memory are sequentially outputted. Therefore, in the case where the period of time which elapses from the time instant that the pickup is shifted from the track until it returns to the former address to start reading data again, is shorter than the time required for taking data out of the memory and reproducing them, the signal is reproduced smoothly, not being intermittent. On the other hand, the microcomputer has stored the position or address where the pickup is shifted. Hence, while the data stored in the memory are being reproduced, the pickup is moved back to the position where it has suspended reading data, to start reading data again. The data thus read are stored in the memory.
If summarized, in order to overcome the difficulty that signals are not continuously reproduced (hereinafter referred to as "reproduction jump" or "sound skip", when applicable) the conventional vibration-resistive mobile CD player employs the following method: When a reproduction start instruction is issued, the CD is rotated at a speed higher than the standard speed, so that the data transfer rate is higher than is required for reproducing signals; that is, after data have been stored to a predetermined amount, the signal reproduction is carried out.
However, the method suffers from the following difficulties: If the amount of data to be stored in the memory is large, the waiting time becomes long which elapses from the time instant that the reproduction start instruction is issued until the signal reproduction is effected. On the other hand, for instance in the case where, in a CD changer adapted to reproduce signals from a plurality of CDs one after another, there is a wait time which is not only the time required for exchanging a CD for another but also the time required for storing the data in memory which are necessary for reproduction. That is, whenever a CD is exchanged for another one, the wait time occurs, which may make the user unpleasant.
If, on the other hand, the amount of data to be stored in memory is small, then the following difficulty is involved: When, during reproduction, even slight vibration makes the pickup difficult to read data from the CD, the reproduction jump occurs. In this case, the sound reproduction is interrupted frequently, which also makes the user unpleasant.