JP2549621B2 - Disk recording and / or reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a disc recording and / or reproducing apparatus, and particularly efficiently records a high bit rate digital signal under the condition that the disc rotation speed is constant. and/
The present invention also relates to a disc recording and / or reproducing apparatus capable of reproducing.

[Prior Art] In a disc recording and / or reproducing apparatus in which a disc is rotating at a constant number of revolutions, the linear velocity increases toward the outer periphery of the disc, and the linear velocity decreases toward the inner periphery of the disc.

Therefore, when recording a digital signal with a constant bit rate, the recording bit length becomes shorter toward the inner circumference,
On the contrary, the recording bit length becomes longer toward the outer periphery. Also, assuming that the shortest bit length that can be recorded and / or reproduced on the innermost circumference of the disc is λ, the recording bit length becomes longer than λ toward the outer circumference, which results in uneconomical use of the recording medium. Become.

Conventionally, in order to eliminate such uneconomical use of the recording medium on the outer circumference of the disc, the disc is divided into a plurality of blocks,
A method of changing the write bit rate for each block has been proposed (for example, Japanese Patent Application No. 56-100824). But,
This method has a problem that a constant bit rate cannot always be realized.

On the other hand, in order to realize a high bit rate, it is necessary to provide a plurality of recording and / or reproducing heads. Therefore, as a disk device which can realize a constant bit rate and uses a plurality of heads, for example, when there are two heads, a device as shown in FIG. 9 can be considered.

In FIG. 9, 1 is a disk, 2 and 3 are heads attached to one slider 10A of the head moving mechanism 10, the first recording area 6 is the first head 2, and the second recording area 7 is Recording and / or reproduction is performed by the second head 3, respectively. 10B is head 2, which is attached to slider 10A,
A slider motor for moving 3 in the radial direction of the disk 1. When recording the digital signal, the first recording area 6 is fixed to the bit rate B ₁ and the second recording area 7 is fixed to the bit rate B ₂ and recorded on the disk 1. here,
The bit rates B ₁ and B ₂ are values obtained by dividing the linear velocities of the innermost circumferences of the respective recording areas 6 and 7 by the shortest recordable and / or reproducible bit length λ. That is, assuming that the number of revolutions of the disk 1 is K and the radii of the innermost peripheries of the recording areas 6 and 7 are R ₁ and R ₂ , the bit rates B ₁ and B ₂ are obtained by the following equations.

Therefore, the total bit rate B _T is B _T = B ₁ + B ₂ . However, although a high bit rate can be realized by this method, the recording bit length becomes long in the portions outside the recording areas 6 and 7, so that the recording capacity cannot be increased.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to perform recording and / or reproducing at a high speed and constant recording and / or reproducing bit rate in a disk device. It is to provide a disc recording and / or reproducing apparatus capable of performing

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is arranged corresponding to each recording and / or reproducing area on a disk rotating at a constant speed, and relatively with the passage of time. The recording and / or reproducing head is provided with one or more recording and / or reproducing heads heading toward the center of the disk and facing away from the center of the disk. The reproducing head records and / or on the disc moving in the radial direction so that the sum of the relative linear velocities of the recording and / or reproducing heads is always a constant value with respect to the relative linear velocity between the reproducing head and the disc. In a digital disk recording and / or reproducing apparatus for reproducing, a certain recording and / or reproducing
Alternatively, in order to record and / or reproduce the reproduction bit rate by using all of the recording and / or reproducing heads at the same time, recording and / or reproducing toward the center of the disc.
Or, for each of the recording and / or reproducing heads that move away from the center of the reproducing head and the disc,
It is characterized by having means for distributing the bit rate in proportion to the disk radial position.

[Operation] According to the configuration of the present invention, a constant linear velocity is realized by a plurality of heads, and a constant recording and / or reproducing bit rate is simultaneously applied to a plurality of heads at their positions (disk radius).
And simultaneously record / reproduce with the plurality of heads. Thereby, high-speed and constant bit rate recording / reproduction can be realized for the first time, and thus high-speed and constant bit rate recording / reproduction such as a moving image can be realized for the first time by the present invention.

Moreover, since the digital signal is recorded on the entire surface of the disc with the same recording bit length, the reproduction equalizer becomes simple. For example, sample hold type equalizer (1984
The National Conference of the Institute of Television Engineers of Japan, 7-6) can be used to configure the equalizer with the clock signal reproduced from the recorded signal, which is optimal when the bit rate changes as in the present invention, and tap gain adjustment is also recorded. Since the bit length is constant, it only needs to be set once. Therefore, the signal recorded at any position on the disc can be reproduced without adjustment.

As described above, according to the present invention, there is an advantage that the reproduction equalizer, which is one of the most important circuits when reproducing the signal recorded in the disc recording / reproducing apparatus, can be configured very easily.

The present invention can be used not only for recording / reproducing digital signals, but also for recording / reproducing analog signals to obtain desired effects.

EXAMPLES The present invention will be described in detail below with reference to the drawings.

First, let us consider a case where the shortest recordable / reproducible bit length is λ, the number of heads is 2N (N = integer), and the disc is divided into 2N recording areas to record a digital signal. If the distances of the 2N heads from the center of the disk, that is, the radial positions, are r ₁ , r ₂ , ..., R _2N , the total recordable and reproducible bit rate B _T is given by the following equation.

Therefore, If it is possible to control each position of the 2N heads so that is always constant, K _T and λ are constants, so that B _T is also a constant, and it is possible to always record and reproduce digital signals at a constant bit rate. Become.

Therefore, in the case of N = 1, that is, 2 × 1 = 2 heads, FIG. 1 shows an embodiment of the present invention for controlling the positions of these two heads as described above.

In FIG. 1, 11 is a slider 11A and this slider 1
A first motor comprising a slider motor 11B for moving the first head 21 attached to 1A inward in the radial direction of the disk 1.
Head moving mechanism, 12 is a slider 12A, and this slider 1
2nd head composed of a slider motor 12B for moving the second head 22 attached to 2A outward in the radial direction of the disk 1.
Head moving mechanism.

If the first head 21 is displaced inwardly of the disc 1 by the distance Δ and the second head 22 is displaced outwardly of the disc 1 by the same distance Δ, r in the equation (4) is satisfied. Is r = (r ₁ −Δ) + (r ₂ + Δ) = r ₁ + r ₂ and r is constant, so the total bit rate B _T
Is constant. That is, the sum of the relative linear velocities of the heads 21 and 22 with respect to the disk 1 is always constant. In FIG. 1, 23 is a recording area of the first head 21, and 24 is a recording area of the second head 22.

Next, FIG. 2 shows the case of N = 2, that is, the case of four heads. Here, the first head 21 and the third head 25 are attached to the slider 11A of the first head moving mechanism 11, and the first recording area 27 and the third recording area 29 of the disk 1 are Recording is performed from the outside to the inside. On the other hand, the second head 22 and the fourth head 26 are attached to the slider 12A of the second head moving mechanism 12,
Recording is performed from the inner side to the outer side of the fourth recording area 30 and the second recording area 28, respectively.

Therefore, the head 21 is moved by the first head moving mechanism 11.
And 25 move inwardly of the disk 1 by Δ, and the heads 22 and 26 move outwardly by the same distance Δ by the second head moving mechanism 12, r in the equation (4) becomes r = (r _1- Δ) + (r _3-
Δ) + (r ₂ + Δ) + (r ₄ + Δ) = r ₁ + r ₂ + r ₃ + r ₄ and r is constant, and thus the total bit rate B _T is also constant in this case.

Thus, in the present invention, each head 21, 22, 25 and 26 is
The sum of the relative linear velocities with respect to the disk 1 is always constant. In that case, the bit rate of each head must be changed according to the radial position. That is, assuming that the radial position of the i-th head is r _i , the bit rate Bi at this head is given by the following equation.

In this equation (5), since B _T , r is constant, it is necessary to change the bit rate in proportion to the radial position r _{i of the} head. That is, the bit allocation to each head must be changed according to the head radial position (track).

With the above configuration, a high bit rate can be realized due to the multi-head configuration having a plurality of heads, and the bit length becomes the shortest bit length that can be recorded / reproduced on all tracks. It is possible to realize a disc recording / reproducing apparatus having a feature that a surface can be effectively used and a constant bit rate is always obtained.
Therefore, for example, a signal requiring a large memory capacity at a high bit rate, such as a digital image signal, can be easily recorded / reproduced by the disc recording / reproducing apparatus according to the present invention.

 Next, a detailed example of the present invention will be described.

Third example of the case where the number of heads is 2 (N = 1)
Shown in the figure. Here, in the disc 1, the recording area is
From the position of radius S to the position of radius R. The first head 21 is arranged at the outermost circumference (r ₁ = R), and the second head 22 is arranged at the innermost circumference (r ₂ = S). When the disk 1 is rotated K times per second, the total recordable bit rate B _T is given by the following equation.

Now, the first head 21 and the second head 22 are respectively moved inward and outward in the radial direction so that the sum of the radial positions of the heads 21 and 22 is always r = r ₁ + r ₂ is equal to R + S. To be

In moving the heads 21 and 22 in this way,
In the example shown in FIG. 3, the two head moving mechanisms 11 shown in FIG.
And 12 are integrally configured. That is, on the base 31 having a portion extending substantially in the radial direction of the disk 1, a rotary shaft 32 provided corresponding to the vicinity of the center of the disk 1 spreads substantially in the radial direction of the disk 1 for moving two heads. rail
Arrange 33 and 34 in a generally V-shape. A roller 35 is provided on the base 31 at a position corresponding to the outside of the disk 1, and the roller 35 is rotationally driven by a motor (not shown). Between the roller 35 and the rotary shaft 32, a rail 33 and
A steel belt 36 is stretched along 34. This belt 36
The heads 21 and 22 are fixed to the rails 33 and 34 so as to be movable along the rails 33 and 34. Here, both heads 21 and 22 are fixed to the steel belt 36 so that the radial position of the head 22 becomes S when the radial position of the head 21 is R. In this example, the slider motor is only for rotating the roller 35, and the number of motors is smaller than that in the case of FIGS. 1 and 2.

In such a configuration, the roller 35 is rotated by the motor and the steel belt 36 is moved, so that when the first head 21 moves a distance Δ toward the center of the disk 1, the second head 22 moves outside. Similarly, move for a distance Δ toward. That is, r ₁ = R−Δr ₂ = S + Δ. Therefore, the sum of the two is always a constant value R + S. Therefore, from the equation (6), the total bit rate B _T is always a constant value.

Next, the bit allocation among these heads will be described. When a signal is recorded in the disc recording / reproducing apparatus shown in FIG. 3, the circuit configuration shown in FIG. 4 is used, for example.

In FIG. 4, 41, 42, 43 and 44, one-revolution buffer memory for temporarily accumulating the signals to be recorded in one revolution of the disc among the input digital signals, and 45 are pulses (1 Rotation pulse), an R / W control circuit for generating a read enable signal RE and a write enable signal WE for each of the heads 21 and 22, and 46 sets read addresses and write addresses of the buffer memories 41 to 44 to a desired state. An address reset circuit for resetting. 47 and 48 are heads 21 and
It is a clock frequency conversion circuit that determines the clock frequency at which the address is advanced based on the radial position information on the 22 disks. 49 and 50 are address generators that increment the address based on the clock from each of the clock frequency conversion circuits 47 and 48.

Here, the one-turn buffer memory 41 and 43 is the first head 21.
One pair of the buffer memories 41 and 43 writes and the other reads, and the buffer memories 41 and 43 read and write during the next one rotation for each rotation of the disk. Replace. That is, for each rotation of the disk, both buffer memories 41 and 43 are
The writing and reading modes are alternately switched between and. Such switching is controlled by the RE and WE signals from the R / W control circuit 45.

Similarly, the buffer memories 42 and 44 also operate as a pair with the second head 22, and the writing and reading modes are alternately switched every rotation of the disk.

For example, assuming that the data for one rotation of the disk is being stored in the one-turn buffer memories 41 and 42, the memory contents are read from the one-turn buffer memories 43 and 44, and the first head 21 and the first head 21 are read, respectively. It is sent to the second head 22. The read clock in that case is determined by the clock frequency generated in the clock frequency conversion circuits 47 and 48 according to the radial position of each head 21, 22, and is sequentially generated from the address generators 49 and 50 in accordance with the clock frequency. By outputting the address, the contents of the memories 43 and 44 are read out.

That is, the content stored in the one-turn buffer memory 43 is the first
Is read from the first address at a clock frequency determined by the radial position of the head 21 and sent to the first head 21. On the other hand, the contents stored in the one-turn buffer memory 44 are stored in the second head from the last address to the first address.
It is read at the clock frequency determined by the radial position of 22.

In this way, the data read from the buffer memories 43 and 44 are transferred to the first and second heads 21 and 22, respectively, but one rotation pulse of the disk is R / W.
When it is input to the control circuit 45, the write and read enable states are switched, and the output of the address reset circuit 46 causes the address generators 49 and 50.
Is driven to reset the read address and write address of the one-turn buffer memories 41 to 44 to the desired state. That is, of the one-turn buffer memories 41 to 44,
It is set to the last address for the memory which is in the read state and transfers the signal to the second head 22, and is set to the first address for the other memories. After that, the one-turn buffer memories 41 and 42 operate as a read memory, and the one-turn buffer memories 43 and 44 operate as a write memory. After that, the same process as described above is repeated.

In the circuit arrangement of FIG. 4, two heads 21 and
Since the relative positional relationship of 22 is predetermined, if the radial position information of one of the heads is detected, the radial position information of the other head can be calculated. Therefore, the clock frequency conversion circuit has only one system. Is sufficient, and the circuit configuration becomes simpler.

Furthermore, since the same signal is written to the one-turn buffer memories 41 and 43 and the one-turn buffer memories 42 and 44, respectively, they are simultaneously written by starting from the first address and the last address. When using a buffer memory capable of individually reading the signals that have been read, only two buffer memories can be commonly used for a plurality of heads without providing two systems of these buffer memories, which also leads to a circuit configuration. Can be simplified.

In order to reproduce the signal from the disk on which the digital signal is recorded as described above, the clock signal is first separated and reproduced from the signal taken out from the head, and the digital signal is demodulated based on this. This process is similar to the reproducing process in a normal digital signal recording / reproducing apparatus.
However, in the present invention, since the clock frequency changes depending on the radial position of the head, it is necessary to adopt a digital modulation system that facilitates the reproduction of the clock signal as the system and to use a clock regenerator with a fast rise.

Next, the present invention will be described by taking a more specific case as an example. The present invention is suitable for recording a high bit rate and large capacity digital signal while rotating the disk at a constant rotation speed. As an example, the present invention will be applied to the case of recording a moving image signal for consideration.

Generally, the bit rate of the image signal is 100 Mbit /
More than a second. As the disk device, an optical disk device and a magneto-optical disk device will be considered. These disk devices are as follows. Only one disc shall be used, and its diameter shall be 30 cm, enabling double-sided recording. The track pitch T is 2 μm and the shortest bit length λ.
= 1 μm. The rotation speed of the disc is 30 rotations / second so that one television image (one frame) can be recorded with one rotation.

In such a disk device, the bit rate can be maximized at the outermost circumference (R = 15 cm), and the bit rate is as follows.

Therefore, in order to record / reproduce a signal having a bit rate of 100 megabits / second, it is necessary to use both sides of the disc and to make a multi-head with two or more heads on each side.

Now, using both sides of one disc, 2 per side
We will use 3 heads. That is, in this case, it is necessary to allocate two heads to one side of the disk to realize a total bit rate of 50 megabits / second. Using the disc device according to the present invention, the recordable time of the image signal is compared and examined between the conventional disc device and the disc device according to the present invention. First, a disk device according to the related art will be considered. Shown earlier (1)
And the following equation is established from the equation (2).

Here, substituting K = 30, λ = 1 μm, B _T = 50 megabits / second, Becomes Furthermore, the following formula must hold.

Wherein _{R-R 1 = R 1 -R} 2, since it is R = 150 mm, from _{2R 1 -R 2 = 150mm (8} ) (7) and _{(8), R 1 = 138.4mm, R 2} = 126.9 mm. Therefore, the recordable time t is Becomes

Next, the disk device according to the present invention will be examined. Since the outermost circumference (R = 15 cm) of the disk is 28.3 megabits / second, in order to realize 50 megabits / second, the innermost circumference (radius S) must satisfy 21.7 megabits / second. Therefore, the following equation holds.

Therefore, the recordable time t is as follows.

Here, let us compare equations (9) and (11).

The improvement rate α of the recordable time according to the present invention is as follows.

That is, according to the present invention, compared with the prior art, 1.5
It is possible to configure a large-capacity disk device with a recording time that is doubled.

The head moving mechanism for the double-sided recording disk used in this embodiment is not the reverse moving mechanism for a plurality of heads in single-sided recording as shown in FIGS. 1 to 3, but is shown in FIG. 5, for example. As shown, it is more preferable that the plurality of heads arranged on both front and back surfaces of the disk move in opposite directions only in the front and back relationship.

That is, in FIG. 5, recording surfaces 51 and 52 are provided on both sides of the disk 1, and the upper and lower recording surfaces 51 and 52 are respectively provided with first and second recording areas 51-1 and 15-2 and 52. -1 and 52-2, respectively,
Assign it. The head moving mechanisms 53 and 54 arranged on both sides of the disk 1 are provided with heads 55, 56 and 57, respectively.
Place 58.

Here, the head moving mechanism 53 is configured to move toward the center of the disk 1, and the head moving mechanism 54 is configured to move toward the outer peripheral direction of the disk 1. And head 55
And 56 are mounted so as to be located at the outer peripheral ends of the first and second recording areas 51-1 and 51-2, respectively, when the head moving mechanism 53 is at the outermost position. head
57 and 58 are attached so as to be located at the inner peripheral ends of the first and second recording areas 52-1 and 52-2, respectively, when the head moving mechanism 54 is at the innermost position.

Reference numeral 59 denotes a spindle motor that drives the disk 1 to rotate.

In this embodiment, heads arranged on both sides of the disk
55 and 58 and heads 56 and 57 are operated in pairs.

As described above, when an even number of disk recording surfaces such as a double-sided disk are used at the same time, a plurality of heads can be mounted on one head moving mechanism, so that the structure of the head moving mechanism is simplified. For example, when two or more double-sided discs are used, as shown in FIG. 6, a head moving mechanism as shown in FIG. 5 is applied to two discs 1 and 1'arranged at a predetermined interval. 54, 53, 53 'are sequentially stacked, and two more heads are placed on the upper surface of the head moving mechanism 53.
7'and 58 'are arranged similarly to the heads 57 and 58, and a third head moving mechanism 5 similar to the head moving mechanism 53 is provided.
The second disk 1'is arranged so as to sandwich 3'above the head moving mechanism 53, and further two heads 55 'and 56' are provided in the third head moving mechanism 53 '.
It may be arranged in the same manner as 56.

The present invention is not limited to the above-described embodiment, and for example, two heads having the positional relationship shown in FIG.
61 and 62 may be fixedly arranged on the base 63, and the disk 1 may be moved in the direction of the arrow with respect to the heads 61 and 62. It is sufficient that the relative positional relationship of the two changes in the directions opposite to each other in the radial direction of the disk.

Alternatively, as shown in FIG. 8, both ends of a pulley 72 attached to a roller 71 are fixed to the center of the rotating shaft of the disk 1 via springs 73 and 74. Two heads 75 and 76 are fixed to the pulley 72 as shown. With the above configuration, by rotating the roller 71 in the direction of the arrow, the head
75 and 76 may move in the recording areas 23 and 24, respectively, in the radial direction of the arrow in the figure. In this example, it is necessary to provide a rail that accurately guides the two heads 75 and 76.

[Effect of the Invention] As described above, according to the present invention, a constant linear velocity is realized by a plurality of heads, and a constant recording and / or reproducing bit rate is simultaneously applied to a plurality of heads at their positions (disk radii). Since the recording / reproducing is performed at the same time by the plurality of heads, the recording / reproducing at a high speed and a constant bit rate can be realized for the first time. Furthermore, this has the effect that recording / reproduction at a high speed and a constant bit rate such as a moving image can be realized for the first time.
Therefore, the present invention can be expected to be important when recording a moving image on a main recording medium (magnetic disk, optical disk) in the multimedia age.

Moreover, since the same recording bit length is used for recording on the entire surface of the disc, the reproduction equalizer becomes simple. For example, sample hold type equalizer (1984
By using the TV conference national conference proceedings 7-6), the equalizer can be configured with the clock signal reproduced from the recorded signal, which is optimal when the bit rate changes as in the present invention. Since the recording bit length is constant, the gain adjustment need only be set once.
Therefore, the signal recorded at any position on the disc can be reproduced without adjustment.

As described above, according to the present invention, there is an advantage that the reproduction equalizer, which is one of the most important circuits when reproducing the signal recorded in the disk device, can be configured very easily.

Furthermore, in the present invention, since the amount of information that can be recorded per predetermined rotation angle of the disc is always constant, it is possible to record, for example, one frame image of a digital television signal during one rotation of the disc. Therefore, it becomes possible to randomly access and retrieve any image during signal reproduction.

Of course, the present invention can be used not only for recording / reproducing digital signals but also for recording / reproducing analog signals such as FM signals to obtain the desired effects. In this case, the concept corresponding to the recording bit length of the digital signal is the recording wavelength of the carrier frequency, but the recording signal length is used as a term that includes both.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, FIG. 3 is a block diagram showing yet another embodiment of the present invention, and FIG. FIG. 5 is a block diagram showing an embodiment of a circuit for changing the bit rates of writing and reading digital signals according to the radial positions of two heads, and FIG. 5 shows the case where an even number of disk recording surfaces are used. FIG. 6 is a sectional view showing an embodiment of the disk device of the present invention in which the head moving mechanism is simplified, FIG. 6 is a sectional view showing a modification of FIG. 5, and FIG. 7 is still another embodiment of the present invention. FIG. 8 is a configuration diagram showing still another embodiment of the present invention, and FIG. 9 is a configuration diagram showing an example of a conventional disk device having a plurality of heads and realizing a high bit rate. Is. 1,1 '... disk, 2,3,21,22,25,26,55,56,57,58,55', 56 ', 57', 58 ', 6
1,62,75,76 ... Head, 6,7,23,24,27,28,29,30,51-1,51-2,52-1,52-2 ...
Recording area, 10,11,12,53,53 ′, 54 …… Head moving mechanism, 10A, 11A, 12A …… Slider, 10B, 11B, 12B …… Slider motor, 31 …… Base, 32 …… Rotating shaft , 33,34 …… Head moving rail, 35 …… Roller, 36 …… Steel belt, 41,42,43,44 …… 1 rotation buffer memory, 45 …… R / W control circuit, 46 …… Address reset Circuit, 47,48 …… Clock frequency conversion circuit, 49,50 …… Address generator, 51,51 ′ …… Upper surface recording surface, 52,52 ′ …… Lower surface recording surface, 59 …… Spindle motor, 63 …… Base, 71 ... Roller, 72 ... Pulley, 73,74 ... Spring, R ... Disc radius, R1 ... Innermost radius of the first recording area, R2 ... Innermost radius of the second recording area Radius, S ... Innermost radius of recording area.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-69014 (JP, A) Actually opened 60-12805 (JP, U) Actually opened 56-2175 (JP, U)

Claims (1)

(57) [Claims] 1. One or more recording and / or recording discs which are arranged corresponding to respective recording and / or reproducing regions on a disc rotating at a constant speed, and which are relatively directed toward the center of the disc over time. One or more recording and / or reproducing heads facing away from the center of the disc relative to the reproducing head, the recording and / or reproducing heads relating to their respective relative linear velocities to the disc; In a digital disk recording and / or reproducing apparatus for recording and / or reproducing on a disk moving in a radial direction such that the sum of the relative linear velocities of the recording and / or reproducing heads always becomes a constant value, The recording and / or reproducing bit rate is recorded and / or recorded by simultaneously using all of the recording and / or reproducing heads. Or, for reproduction, for each of the recording and / or reproducing head directed toward the center of the disk and the recording and / or reproducing head directed away from the center of the disk, the bit is proportional to the disk radial position. A disk recording and / or reproducing apparatus having means for allocating a rate.