Recording/Reproducing Apparatus That Utilizes the Servo Clock Signals to Form Read and Write Clock Signals With Different Frequencies

1. A magneto-optical disc recording and reproducing apparatus comprising: signal recording and reproducing means including optical means for radiating a light beam onto a magneto-optical disc housed within a disc cartridge and for receiving light returning from the disc, the disc having a signal recording region divided from an inner periphery to an outer periphery into a plurality of concentric signal recording zones, each signal recording zone having a plurality of information elements formed on the signal recording region with a substantially equal line recording density so that the number of information elements storable per track increases from zone to zone from the inner periphery to the outer periphery, whereby the information elements are reproduced at increasing frequencies from the innermost zone to the outermost zone, and a plurality of servo clock signals formed in the zones, whereby the servo clock signals recorded at different radial distances from the center of the disc are reproduced at a substantially constant frequency; magnetic field generating means for applying a magnetic field when information signals are being recorded on the disc; rotating driving means for rotatably driving the disc at a substantially constant angular velocity; loading means for loading the disc cartridge onto the signal recording and reproducing means and for unloading the disc cartridge from the signal recording and reproducing means, and controlling means for controlling the signal recording and reproducing means and for converting the substantially constant frequency reproduced from the servo clock signals for use as plural channel clock frequencies for reproducing and recording signals in the signal recording zones, each signal recording zone having one corresponding channel clock frequency, such that the channel clock frequencies of signal recording zones located at larger radial distances from the center of the disc are higher than channel clock frequencies of signal recording zones located at smaller radial distances from the center of the disc.

2. The magneto-optical disc recording and reproducing apparatus as claimed in claim 1 wherein the disc cartridge houses the disc during recording and reproducing, further comprising movement means for moving the rotating driving means after the disc cartridge has been loaded onto the signal recording and reproducing means by the loading means, the movement means moving the rotating driving means from a non-rotating position spaced apart from the disc and the disc cartridge to a rotating position closer to the disc and the disc cartridge.

3. The magneto-optical disc recording and reproducing apparatus as claimed in claim 2 further comprising detection means for detecting that the disc cartridge has reached a predetermined position in the apparatus, the controlling means further for controlling the movement means based on a detection output from the detection means.

4. The magneto-optical disc recording and reproducing apparatus as claimed in claim 2 further comprising positioning means for positioning the disc cartridge onto the rotating driving means when the movement means moves the rotating driving means to the rotating position after the disc cartridge has been inserted via a cartridge opening.

5. The magneto-optical disc recording and reproducing apparatus as claimed in claim 1, the apparatus further comprising an outer casing including at least a lower chassis in parallel with the disc when the disc is loaded onto the signal recording and reproducing means and a cartridge opening on a side of the outer casing, and wherein the optical means include: a fixed optical system section at least having a light source for emitting the light beam, light detection means, and an optical element for focusing error detection, the fixed optical system located adjacent to the disc within the outer casing; a movable optical system located adjacent to a lower optical surface of the disc when the disc is loaded onto the signal recording and reproducing means, the movable optical system mounted to move along a radius of the disc; feed means for moving the movable optical system radially across the disc the feed means including a feed motor and a pair of parallel guides in parallel with the disc and the lower chassis; optical support means for movably supporting the movable optical system along the parallel guides, the support means having a lateral side along each of the parallel guides; and rolling means attached to the optical support means for rolling on and holding the parallel guides, the rolling means including at least two rows of at least three guide rolls, each row of guide rolls positioned along each lateral side of the optical support means, such that at least one guide roll of each row of guide rolls extends upward at an angle to rest against an upper surface of one of the parallel guides and the remaining guide rolls in the same row of guide rolls extend downward at an angle to rest against a lower surface of the same parallel guide.

6. The magneto-optical disc recording and reproducing apparatus as claimed in claim 5 wherein the loading means include a cartridge holder for horizontally guiding and holding the disc cartridge as it is inserted via the cartridge opening, and biasing means for biasing the disc cartridge toward the lower chassis when the disc cartridge is inserted into the cartridge holder.

7. A magneto-optical disc recording and reproducing apparatus for a magneto-optical disc, said apparatus comprising: said magneto-optical disc having a plurality of concentric tracks or a spiral track for recording data and being housed within a disc cartridge, the diameter of said magneto-optical disc being substantially 64 mm and the storage capacity of said magneto-optical disc being at least 191 MB, said disc having a signal recording region divided from an inner periphery to an outer periphery into a plurality of concentric signal recording zones, each signal recording zone having a plurality of sectors formed on the signal recording region with a substantially equal line recording density so that the number of sectors storable per track increases from zone to zone from the inner periphery to the outer periphery, whereby the sectors are reproduced at increasing frequencies from the innermost zone to the outermost zone, and a plurality of servo clock signals are formed in the zone, whereby the servo clock signals recorded at different radial distances from the center of said disc are reproduced at a substantially constant frequency; signal recording and reproducing means including optical means for radiating a light beam onto said magneto-optical disc and for receiving a light beam returning from said disc; magnetic field generating means arranged to oppose to said optical means through said disc and for applying a vertical magnetic field according to recording data from said signal recording and reproducing means when information signals are being recorded on said disc, said magnetic field generating means being moved with said optical means in the radial direction of said disc; rotating driving means for rotatably driving said disc at a constant angular velocity; loading means for loading said disc cartridge onto said signal recording and reproducing means and unloading said disc cartridge from said recording and reproducing means; and controlling means for converting a substantially constant frequency reproduced from the servo clock signals for use as plural channel clock frequencies for reproducing and recording signals in the signal recording zones, each signal recording zone having one corresponding channel clock frequency such that the channel clock frequencies of the signal recording zones located at larger radial distances from the center of said disc are higher than the channel clock frequencies of signal recording zones located at smaller radial distances from the center of said disc, and for controlling said recording and reproducing means according to the channel clock frequencies.