JPS59186178A - Random access device of clv disc - Google Patents

Abstract

PURPOSE:To shorten access time and stabilize rotation control of a disc motor by providing a disc rotation number feedback control system in response to an object rotating reference corresponding to a command track position. CONSTITUTION:An object reference generating circuit 17 and a pickup feeding control circuit 7 are controlled from a keyboard 16 via a command device 15 such as CPU in response to a track address and a contact A of a switch circuit 13, for recording and reproducing feedback system is changed over to a contact B. Then, a pickup 4 is moved in a rapid speed to an object position and the number of revolutions of a disc motor 2 is controlled by means of feedback in response to the comparison by a phase comparator 19 between a reference frequency signal in response to the address from the circuit 17 and an output from a rotation detecting device 3. Thus, the address reading based on a synchronizing signal on a track near the object track is attained easily and when the address is coincident with a designated address, the switch 13 is changed over by the device 15. Thus, the access period of the disc having a prescribed relative speed to the pickup is decreased and the rotation control is stabilized.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is applicable to recording or reproducing information using a disk whose rotation is controlled at a constant relative speed to a pickup, such as a video recorder, document file, data file, etc. The present invention relates to a random access device in a device.

(Constitution of Conventional Example and its Problems) Two methods have been proposed as disk rotation control methods for devices that record or reproduce information using a disk.

One of them is a constant angular velocity rotation control method (hereinafter referred to as CAV method), in which the rotational angular velocity of the disk is constant at any playback position. For example, in the case of a video disc, the frame frequency or an integer fraction thereof is selected, and a typical example is 1800. 900
The rotation of the disk can always be controlled at speeds such as r, p, and m.

From this, since the synchronization signals are aligned in the radial direction of the disk, (1) trick plays by jumping the playback trunk can be easily performed, (2) the target position of the target moving at high speed can be easily calculated, (3) There are advantages such as a simpler rotation control system. On the other hand, since the recording density of information on the inner and outer peripheries is different, the utilization rate of the disk surface on the outer periphery is reduced, the amount of information that can be recorded is small, and the recording time is short.

The other method is the constant angular velocity rotation control method (hereinafter referred to as CLV method), which keeps the relative speed between the disk and the pickup constant so that the recording density of information is constant at any position on the disk. It is a method.

This method has the advantage of making the most of the disk surface and allowing long-time recording, but it also reduces the number of rotations of the disk when performing jump playback such as the above-mentioned trick play or when changing the playback position by moving at high speed. Conventionally, the disk rotation speed in the CLV system is changed by keeping the period of the reproduced synchronization signal constant. Therefore, when moving in the radial direction at high speed, the rotation speed of the disk motor is controlled by the synchronization signal and reference frequency at that position after the pickup device moves, so the time it takes for the pickup device to move is This remained as a wasted time element, and this was a problem when using the CLV method in a system that requires a high-speed response such as a data file.

Also, when the pickup is moving at high speed or when performing a trunk jump after approaching the target truck, the first
As shown in the figure, since the synchronization signals S recorded on the tracks T on the disk are not aligned radially, the read synchronization signals become discontinuous as shown in Figure 2, and the rotation control system There was a problem that not only was the data extremely unstable, but the address being played back was also unstable to read.

(Object of the Invention) The present invention has been made in view of the problems of the above-mentioned conventional example. The present invention also provides a CLV disk random access device with improved rotation control stability.

(Structure of the Invention) In order to achieve the above object, in the apparatus of the present invention,
It has a 6- configuration with two disk motor control circuits.

One of them is 1. During normal continuous recording or playback, the phase of the synchronization signal read out is compared with the reference frequency, and the rotation of the disk motor is controlled so that the period of the synchronization signal is constant. This is a rotation control circuit.

The other type is a control circuit used when moving the pickup device at high speed to suddenly change the recording or playback position or when jumping a track, and is used from a device such as a microconbeater that issues a command to change the position. Given the later target rotation standard, the phase or speed is compared with the rotation detector of the disk motor, and while the pink-up device is moving at high speed, the rotation speed of the disk motor is kept close to the specified rotation speed at the target position. This is the second rotation control circuit for rotation control. Furthermore, a determination circuit and a switching circuit are provided for switching the control system from the second rotation control circuit to the first rotation control circuit after jumping seven times to the target track.

(Explanation of Examples) Examples will be described in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention.

Reference numeral 1 denotes a disk, which is rotationally driven by a disk motor 2. 3 is a rotation detector of the disk motor, which outputs a frequency proportional to the rotation speed of the disk motor (depending on the configuration, a voltage U'' force may be used).

Reference numeral 4 denotes a pink-up device, which incorporates optical elements and detectors for reading and recording information recorded on the disk, and a trunk tracking servo element for accurately following the information track. The pick amplifier device 4 is connected to a feed motor 6 by a feed screw 5,
It is adapted to be fed in the radial direction of the disk 1. 7
is a feed motor control circuit, and during recording or playback, l
・It works as a feed servo for tracking the rack, and performs high-speed position servo during random access to search for an arbitrary position.

8 is a demodulation circuit that demodulates the signal read out from the pink-up device, and includes a synchronization separation circuit 9 and an address detection circuit 1.
Although not shown in the figure, the read information is output to the other device as the output of this device. Reference numeral 11 denotes a rotation reference generation circuit pl, which is composed of a crystal oscillator and a frequency dividing circuit, and outputs a signal of a constant frequency. Its frequency is the same as that of the established synchronous newsletter. 12 is a phase comparator, which compares the phases of the output of the synchronous separation circuit 9 and the output of the rotation reference generation circuit 11, and
The rotation of the disk motor 2 is controlled through the drive circuit I4 and the drive circuit I4, and the above loop accurately controls the rotation during normal recording or reproduction.

It is a command device composed of 15 microcomputers, etc., and it can input information from a keyboard 6 or an external command device, the output of the address detection circuit 10, and the overall status, and controls the device. 17 is a target reference generation circuit that outputs a signal of an unnecessary frequency based on data given from the command device 15;
It consists of a crystal oscillator, a frequency dividing circuit with a variable division ratio, etc. 18 is a waveform shaping circuit which amplifies the output of the rotation detector 3 and converts it into a rectangular wave. This rectangular wave is transmitted to the phase comparator 19-9.
= is inputted to the output terminal 1, and the phase thereof is compared with the output of the target reference generation circuit 17. Its output becomes one input of the switch circuit 13.

Next, the operation of this embodiment will be explained. First, when moving the playback position to a desired position, the target address is input from the keyboard 16. The command device 15 immediately outputs the target position to the feed control circuit 7, and at the same time outputs data of the rotation reference frequency at the target address to the target reference generation circuit 17, and switches the switch circuit 13 to the B side. As a result, the pick amplifier device moves to the target position at high speed, and at the same time, the rotational speed of the disk motor is also controlled by rotating around the rotational speed so that the rotational speed can be monitored, making it easy to read the address signal. A trunk jump signal is given by the command device 15 to the track following servo element so that the target trunk matches the target trunk, and the switch circuit is returned to the A side after confirming that the trunk jump matches the target trunk.

Here, the method of the second rotation control circuit was explained as a phase comparison method, but this accuracy is good even if it is relatively low, and it is important that the address signal can be read accurately and that the rotation by the first control circuit is accurate. Since the difference from the number is not very large (approximately 5%), it is enough to add a, so a speed comparison method is also sufficient. In this case, the target reference generation circuit 17 is composed of a D/A converter or the like that generates a voltage instead of a frequency, and the voltage and a signal obtained by frequency-voltage conversion (F-V conversion) of the output of the rotation detector 3 are combined. By comparing voltages with a comparator 19 consisting of a differential amplifier, rotation control during high-speed access can be performed.

FIGS. 4(a) and 4(b) compare changes in the rotational speed of the disk motor and changes in the playback position of the pickup device during high-speed access in this embodiment and the conventional example, respectively. In the figure, the conditions such as the disc inertia and the weight of the pink-up device are the same, so
The curve of the position of the pickup device and the curve showing the speed change of the disk motor are the same, but in this example (
In FIG. 4(a), it can be seen that the rotational speed of the disk motor changes in parallel with the change in the position of the pink-up device. Therefore, the conventional method (Figure 4 (
In b)), the access time, which was determined by the sum of the pink amplifier device movement time T1 and the disk motor rotation change time T2, is now determined only by the time required by the disk motor, T2, and the response time is T4. It can be done quickly.

If the torque of the disk motor is selected according to the inertia condition of the load (T, -: T2), it is possible to create a system that is comparable in access performance to the cAV system.

When the pink amplifier device moves (T1) including the jump period in the conventional example, the detection of the synchronization signal is unstable because it crosses the recording rack at high speed, and the rotation of the disk motor is unstable. However, according to the present invention, it is possible to prevent such disturbances in the disk motor and improve the stability of the system.

(Effects of the Invention) As explained below, according to the present invention, the access time is shortened and the rotation control of the disk motor is stabilized, so that the amount of recorded information that is originally available in the CLv method is large, and the amount of recorded information is large. It is possible to maximize the advantage of being able to record for a long time, and therefore it has an extremely important effect when applied to systems such as data files.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the state of the synchronization signal arrangement in a CLV disk, FIG. 2 is a diagram showing how the read synchronization signal becomes discontinuous during a conventional jump, etc., and FIG. FIG. 4 is a block diagram showing the configuration of an embodiment. FIG. 4 is a diagram showing an example of changes in the rotation speed of the disk motor and the position of the pickup during high-speed access, in which (a) shows this embodiment, and (b)
is a conventional example. 1 ・・・・・・Disc, 2 ・・・・・・
・Disc motor, 3... Rotation detector, 4
...Pickup device, 5...Feed screw, 6...Feed motor, 7...
... Feed control circuit, 8 ... Demodulation circuit,
9... Synchronization separation circuit, 10... Address detection circuit, 11... Rotation reference generation circuit, 12.19... Phase comparator, 13・
......Sinch circuit, 13-14...Drive circuit, 15...Command device, 16...Keyboard, 17...
-Target reference generation circuit, 18... Waveform shaping circuit. Patent Applicant: Matsushita Electric Industrial Co., Ltd. (Example: “Papa Shi1’-1”) Agent: Tsuneji Hoshino -Yumi・1
4- 4th (0) (bl

Claims (1)

[Claims] Information is recorded using a disk which is a disc-shaped recording medium that is rotationally controlled at a constant relative speed (cL) with respect to the pink-up and records at least a synchronization signal and an address signal indicating the position of the information. A device for recording or reproducing a disc, comprising: a disc motor for rotating the disc; a rotation detector that generates a signal with a frequency proportional to the number of revolutions of the disc; a pink amplifier device that reads out signals on the disc; and a pickup device. A track following servo device for accurately following the information track and a feed motor for sending the pickup device in the radial direction of the disk, a synchronization signal detection circuit for detecting the synchronization signal from the output of the pickup device, and a synchronization signal detection circuit for detecting the address signal. an address signal detection circuit for detecting the disc motor; and a speed comparison or phase comparison between the output of the first rotation reference generation circuit and the synchronization signal in order to rotate the disc motor at a predetermined speed, and the address signal detection circuit compares the speed or phase of the output of the first rotation reference generation circuit and the synchronization signal to rotate the disc motor at a predetermined speed. A first rotation control circuit that controls the rotation of the motor; and a second rotation reference generating circuit whose settings are variable in order to rotate the disc motor at a desired speed; and the output of the rotation detector are compared in speed or phased. a second rotation control circuit that compares the signals and controls the rotation of the disk motor based on the signals; a switching circuit that switches between the first rotation control circuit and the second rotation control circuit; and a command for each of the components. and a command device for controlling the entire device, and when the pickup device is moved at high speed to a desired radial position on the disk to search for a target address, the target position is sent to the control circuit of the feed motor. simultaneously causing the second rotation reference generation circuit to generate a rotation reference output at the target address position;
The rotation control circuit controls the rotation of the disk motor, and inputs a trunk jump pulse to the track following servo device so that the difference between the target address and the read address of the address detection circuit becomes zero, and the target address and the read address are completely read out. 1. A random access device for a CLV disk, characterized in that the device detects that a difference between addresses becomes zero and switches rotation control of the disk motor to the first rotation control circuit.