JPS63152057A - Disk clamp device - Google Patents

Abstract

PURPOSE:To clamp always stably and surely by making the clamp force of a disk shiftable and increasing the clamp force at the time of reproducing a composite disk compared to that at the reproducing time of a compact disk. CONSTITUTION:In the case of the disk to be reproduced being a composite disk a system controller 21 transmits a control signal to a clamper driving circuit 50. An electromagnetic coil 49 is therefore driven and the clamp force by the resiliency larger than that between magnets 47, 48, caused between the electromagnetic coil 49 and magnet 47 acts on the composite disk. Namely at the reproduction time of the composite disk having extremely high rotary speed compared to the compact disk, the clamp force of the disk is increased compared to the reproduction time of the compact disk. A sufficient clamp force can thus be given to the composite disk even in case of a high speed rotation.

Description

TECHNICAL FIELD The present invention relates to a disc clamping device, and more particularly to a disc clamping device for use in an apparatus capable of reproducing a recording disc on which digital signals are recorded (hereinafter simply referred to as a disc). .

BACKGROUND ART A disk on which digital signals are recorded is a disk with a diameter of about 120 mm called a compact disk (CD).
A small digital audio disc of Il is known, but recently, a PC with the same size as the disc
M (Pulse Code Modulation)
In addition to signals, discs (hereinafter referred to as composite discs) on which FM-modulated video signals and PCM signals are recorded in a superimposed manner are being developed.

In this composite disc, as shown in FIG.
Information is recorded in a second area (hereinafter referred to as video area) 1b in which a modulated video signal and a PCM audio signal are recorded in a superimposed manner. The video signal contains higher frequency components than the PCM signal, and the frequency spectrum of the signal recorded in the video area 1b is as shown in FIG. In the figure, the component indicated by A is a PCM signal, and the component indicated by B is a video FM signal. Therefore, when recording signals to the video area 1b, it is necessary to increase the rotational speed of the disc compared to when recording to the CD area 1a, and as a result, as a matter of course, during playback, the rotational speed of the disc must be higher than that when recording signals to the CD area 1a. The disc must be played back at a high rotational speed in the video area 1b. As shown in FIG. 6, the rotation speed is several hundred rpm+n in the CD area 1a, whereas in the video area 1b, it is around 2,000 rpm at the innermost edge of the area.
, the rotational speed is extremely high at the outermost periphery, over 1,000 rpa+.

A lead-in area is provided at the beginning of each of the CD area 1a and the video area 1b, and each lead-in area contains an index code related to the recorded content of each area, for example, each small part constituting each area. A first and second index code group corresponding to each area is recorded by repeating the index code indicating the start and end time, etc., and the index code in the audio lead-in area indicates that the disc is composite. Type information indicating whether or not it is a disc is also included.

As mentioned above, when playing a composite disc, the maximum rotation speed reaches over 2,000 RPH, which is a higher rotation speed than that of a compact disc. If the settings are the same as those for the disk, the pressing force will be insufficient and the disk will not be able to be stably clamped. On the other hand, if the pressing force is set based on the composite disc and a large pressing force is applied during playback of any disc, excessive stress will be applied to the spindle in the thrust direction. Motor bearings are subject to stress, etc.
This will lead to a shortened spindle motor life.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a disk clamping device that can always clamp a disk stably and reliably while minimizing the load on the spindle motor.

The disc clamping device according to the present invention is configured to be able to switch the clamping force on the disc, and to increase the clamping force when playing a composite disc compared to when playing a compact disc.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a configuration diagram showing an example of a recording disc reproducing apparatus to which a disc clamping device according to the present invention is applied.

In the figure, a disk 1 placed on a turntable 39 is rotationally driven by a spindle motor 2, and recorded information is read by an optical pickup 3. The pickup 3 includes an optical system including a laser diode, an objective lens, a photodetector, etc., and a disk 1.
A focus actuator that drives the objective lens in the optical axis direction with respect to the information recording surface of the disk, a tracking actuator that shifts the beam spot (information detection point) emitted from the pickup 3 in the disk radial direction with respect to the recording track, etc. has been done. The pickup 3 is mounted on a slider 4 that is movable in the radial direction of the disk, and the slider 4 is linearly driven by a transmission mechanism 6 that uses a slider motor 5 as a drive source and is composed of a combination of a rack and a pinion, for example. A read RF (high frequency) signal output from the pickup 3 is supplied to a video information demodulation system 8 and a digital information demodulation system 9 via an RF amplifier 7.

In the video information demodulation system 8, the RF from the RF amplifier 7
The signal is demodulated into a video signal by a double signal demodulation circuit 10, and then supplied to a time base correction circuit 11 and a separation circuit 12. The separation circuit 12 separates and extracts a horizontal (H) synchronization signal, a vertical (V) synchronization signal, and control data contained in the video signal. The time axis correction circuit 11 includes, for example, a CCD (Cha
It is configured to perform time axis correction by changing the amount of delay of the element in accordance with a control signal from the time axis control circuit 13. The time axis control circuit 13 is
For example, the oscillation output of a crystal oscillator (VCXO) 14 that oscillates in synchronization with a horizontal synchronization signal and its frequency-divided output separated and extracted by the separation circuit 14, and the horizontal synchronization signal and color in the video signal that have passed through the time axis correction circuit 11. It is configured to output a control signal according to the phase difference with the burst signal, and its specific configuration is shown in Japanese Patent Application Laid-Open No. 56-102182.

The time axis corrected video signal is supplied to a selection switch 15 and is also supplied to an A/D (analog/digital) converter 17 via an LPF (low pass filter) 16. In the A/D converter 17, when the video signal is not sampled at a predetermined period, the obtained sample values are sequentially converted into digital data. The output data of this A/D converter 17 is supplied to a video memory 18 consisting of a RAM (Random Access Memory) or the like.

The video memory 18 used has a storage capacity capable of storing at least one field's worth of video information. Address control and mode control of the video memory 18 are performed by a memory control circuit 19. The memory control circuit 19 sequentially reads the data written in each address of the video memory 18 using the clock from the reference clock generation circuit 20, and responds to a write enable signal W output from a system controller 21 to be described later. The configuration is such that control is performed to rewrite the contents of each address in the video memory 18.

The data read from the video memory 18 is
The signal is converted into an analog signal by a (digital/analog) converter 22, and is supplied to the selection switch 15 via the LPF 23. The selection switch 15 is normally located on the a side and supplies the video signal directly supplied from the time axis correction circuit 11 to the video output terminal 24, and is switched to the b side in response to a switching command from the system controller 21 to output the video memory. 18 is selected and supplied to a video output terminal 24.

On the other hand, the digital information demodulation system 9 is provided with a selection switch 25 that switches depending on the area to be played (CD area and video area) when playing a composite disc.
This switch 25 is located on the a side when reproducing the CD area, and on the b side when reproducing the video area, and the switching is performed in response to a switching command issued from the system controller 21.

In the case of a composite disc, as explained in FIG.
The disc rotational speed is extremely different between the area and the video area, and the PCM audio signal is, for example, E F M (
Eight to Fourteen Modulat
ion) signal, and in the video domain, if the digital signal is directly superimposed on the FM-modulated video signal during recording, the EFM signal will have a negative effect on the low-frequency components of the FM video signal. The signal level is the same, but the EFM signal is recorded with the signal level suppressed by several tens of outputs relative to the video carrier (No. 5
(see figure). Therefore, the same EFM signal has different frequency characteristics and amplitude when playing back the CD area and when playing the video area. Therefore, by switching the signal processing system of the reproduced EFM signal between the CD area and the video area, the demodulation system can be changed. The aim is to share the information.

That is, when reproducing the CD area, the reproduced RF signal is EF
The EFM signal has its frequency characteristics compensated for by an equalizer circuit 26 having predetermined equalizing characteristics, and is further amplified by an amplifier 27 with a predetermined gain. On the other hand, in the case of video area playback, F is included in the playback RF signal.
Only the EFM signal included with the M video signal is
The frequency characteristic is compensated by the equalizer circuit 29 which has equalizing characteristics different from that of the equalizer circuit 26, and is further amplified by the amplifier 30 which has a larger gain than the amplifier 27. It is output as an EFM signal with frequency characteristics and amplitude equivalent to those during CD area reproduction.

Incidentally, when playing back a compact disc, the selection switch 25 is always in the state where the a side is selected.

The reproduced EFM signal selected by the selection switch 25 is demodulated and
The signal is supplied to the correction circuit 31. This demodulation/correction circuit 31 demodulates the EFM signal and writes it into a memory such as a RAM, controls the RAM based on the clock from the reference clock generator 32, exchanges data, and performs deinterleaving and the data. Error correction is performed using the parity contained in the data, and control data is further detected. The digital audio signal demodulated and corrected by the demodulation/correction circuit 31 is processed by an audio signal processing circuit 33 consisting of a D/A converter, a deglitcher circuit, etc., and then supplied to left and right channel audio output terminals 34L and 34R. be done.

A detection signal is generated near the travel path of the pickup 3 in the disk radial direction by detecting that the beam spot emitted from the pickup 3 has arrived at a position corresponding to the vicinity of the boundary between the CD area and the video area on the composite disk. A position detector 35 is provided. By generating this detection signal, it is possible to detect that the pickup 3 has reached the video area. As the position detector 35, one having a well-known configuration such as an optical sensor can be used. A detection signal output from the position detector 35 is supplied to the system controller 21.

The system controller 21 is composed of a microcomputer including a CPU (central processing circuit), ROM (read number only memory), RAM, and the like.

This system controller 21 receives the horizontal synchronization signal, vertical synchronization signal and control data from the separation circuit 12, as well as demodulation and control data.
Control data from the correction circuit 31, disc designation information indicating whether the disc to be played back is a compact disc or a composite disc from the operation unit 36, whether the playback area when playing a composite disc is only a CD area or only a video area, or Mode designation information indicating whether it is a double-headed area or the like is supplied. In this system controller 21, the CPU processes input signals according to a program stored in advance in the ROM,
It controls various parts such as the selection switches 15 and 25, the memory control circuit 19, a drive circuit (not shown) for driving the spindle motor 2, a drive circuit 37 for driving the slider motor, and a display section 38.

The disk 1 placed on the turntable 39 is clamped by a clamp mechanism 40 including the turntable 39. The specific configuration of this clamp mechanism 40 will be explained with reference to FIG. 2.

In FIG. 2, a turntable 39 is fixed to a rotating shaft (spindle) 41 of a spindle motor 2, and has a centering hub 42 in a central recess 39a thereof so as to be vertically movable. The bottom surface of the central recess 39a and the centering hub 42
A spring 43 is interposed between the bottom surface and the bottom surface. The disk 1 placed on the turntable 39 is positioned by the tapered surface 42a of the centering hub 42, and then pressed against the turncheaple 39 by the pressing member 44. This pressing member 44 is rotatably held by a holding member 45, and its tip convex portion 44a is attached to the center hole 46 of a member 46 fixed to the tip of the spindle 41.
By fitting into the turntable 6a, it rotates integrally with the turntable 39. The holding member 45 is provided to be vertically movable relative to the turntable 39.

A magnet 47 magnetized in the axial direction of the spindle 41 is attached to the upper surface of the pressing member 44, and a magnet 48 is attached to the surface of the holding member 45 facing the magnet 47 so that the same magnetic poles as the magnet 47 face each other. is attached, and the repulsive force between both magnets 47 and 48 acts as a pressing force on the pressing member 44. Further, an electromagnetic coil 49 is provided around the magnet 48 so as to face the magnetic pole surface of the magnet 47, and when the disk to be reproduced is a composite disk, the electromagnetic coil 49 has a gap between it and the magnet 47. magnet 47
．． A driving current is supplied from the clamper driving circuit 50 in a direction and magnitude that generates a repulsive force larger than the repulsive force between the clampers 48 and 48. The clamper drive circuit 50 is connected to the system controller 2
1 (see Figure 1).

Next, the operation of the disk clamp device according to the present invention having such a configuration will be explained.

First, when the disc 1 is placed on the turntable 39 during playback, the disc 1 is positioned by the tapered surface 42a of the centering hub 42, and then by the pressing force of the pressing member 44 due to the repulsive force between the magnets 47 and 48. It is clamped onto a turntable 39.

In this state, when a start command is issued from the operating section 36, the slider motor 5 is driven via the motor drive circuit 37 under the control of the system controller 21, thereby moving the pickup 3 to the innermost position of the disk. After the pickup 3 reaches the innermost circumference position and focuses the pickup 3, index code information recorded in the audio lead-in area on the innermost circumference of the disc is read. The system controller 21 identifies the type of disc to be played based on this read information. In the case of a composite disc, the index code in the audio lead-in area includes type information indicating that it is a composite disc, so the type of disc can be identified by determining the presence or absence of this type information. can.

When the disc to be played is a compact disc, the system controller 21 controls the clamper drive circuit 5.
No control signal is sent to 0. This results in
The clamping force for compact discs is 47.
Only the pressing force of the pressing member 44 is due to the repulsive force between the pressing members 48. On the other hand, when the disc to be played is a composite disc, the system controller 21 sends a control signal to the clamper drive circuit 50, which drives the electromagnetic coil 49. Magnet 47.48 generated between magnet 47
A clamping force due to a repulsion force greater than the repulsion force between the two ends will act. In other words, when playing a compound disc whose rotation speed is much higher than that of a compact disc,
The clamping force for the disc will be increased compared to when playing back a compact disc. Thereby, sufficient clamping force can be applied to the composite disk even at high speed rotation. Further, since the large clamping force is applied only when reproducing the composite disc, the load on the spindle motor 2 does not increase significantly.

In the above embodiment, a large clamping force is always applied during playback of a composite disc, but the system controller 21 applies the clamping force only when playing back a video area on a composite disc based on the detection output of the position detector 35. It is also possible to send a control signal to the drive circuit 50 so as to apply a large clamping force only during high-speed reproduction, thereby reducing the load on the spindle motor 2 compared to the case of the above embodiment. This means that it can be reduced.

Further, in the clamp mechanism 40 of FIG. 2, the electromagnetic coil 49
When the magnet 47.48 is not driven, the clamping force is obtained by the repulsive force of the magnet 47.48.
A clamping force is obtained by the suction force of
Various modifications are possible, such as a configuration in which the clamping force is obtained by the pie spacing of the springs 52a and 52b.

As described in detail, the disk clamping device according to the present invention is capable of switching the disk clamping force,
Since the structure is such that the clamping force is increased when playing a composite disc compared to when playing a compact disc, the disc can be clamped stably and reliably even when playing a composite disc with an extremely high rotational speed. .

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a recording disc reproducing device to which a disc clamping device according to the present invention is applied, FIG. 2 is a sectional view showing an embodiment of the disc clamping device according to the present invention, and FIG. 3 is a diagram showing an example of the disc clamping device according to the present invention. FIG. 4 is a diagram showing the division of the recording area of the composite disc, and FIG. 5 is a diagram showing the frequency spectrum of the signal recorded in the video area of the composite disc. , FIG. 6 is a diagram showing the division of information recording areas on a composite disc. Explanation of symbols of main parts 1...Disk 2...Spindle motor 3...Optical pickup 5...Slider motor 8...Video Information demodulation system 9... Audio information demodulation system 11... Time axis correction circuit 15.25... Selection switch 18... Video memory 21... ...System controller 39...
・Turntable 40... Clamp mechanism 47.48... Magnet 49... Electromagnetic coil

Claims (3)

[Claims] (1) A first area having a first area in which only a predetermined digital signal is recorded and a second area in which a frequency modulated video signal and a predetermined digital signal are recorded in a superimposed manner.
A disc clamp device in a recording disc playback device capable of playing back a disc and a second disc on which a predetermined digital signal is recorded over the entire area, the disc clamping device being used in a recording disc playback device that can play back a disc placed on a turntable. a pressing member that presses against the disk; an identification means for identifying the type of disc to be played;
A disc clamping device comprising: pressing means for increasing the pressing force of the pressing member when the disc is identified. (2) The disk clamp device according to claim 1, wherein the pressing means increases the pressing force of the pressing member only when reproducing the second area on the first disk. . (3) The pressing means includes a magnet attached to the pressing member and an electromagnetic means that selectively applies electromagnetic force to the magnet. disc clamp device.