JPH0793882A - Signal recording device - Google Patents

Abstract

PURPOSE:To simplify constitution and to access at a high speed by making a disk type recording medium fixed rotation and temporarily storing a signal to be written in the recording medium in a memory means. CONSTITUTION:An optical disk 1 is rotated with the fixed number of rotations N by a spindle motor 2, and the number of rotations N is measured by a pulse generator 3. A memory control circuit 9 performs switching input/output of a memory, supplying a clock to a memory and controlling refresh and the like of a memory. A clock for the memory control circuit 9 is supplied from a clock generating circuit 8 or a clock generating circuit 10, and selection is performed by a switch 23. A memory 11 has capacity of one still picture, and constituted of a dynamic RAM or a static RAM. The device is constituted so that an output of the memory 11 can be connected to either of a laser diode driving circuit 12 or a demodulation circuit 17 by a switch 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recording a signal on an optical disc, a magneto-optical disc, a magnetic disc or the like.

[0002]

2. Description of the Related Art Conventionally, a constant angular velocity method (hereinafter referred to as CAV method) and a constant linear velocity method (hereinafter referred to as CLV method) are known as methods for digitally recording on a disc.

[0003]

Compared to the CLV system, the CAV system does not require a device for controlling the rotation speed of a disc, so that the recording / reproducing device becomes simple. Further, there is an advantage that the access time is short at the time of reproduction, but there is a drawback that the recording capacity of the entire disc is smaller than that of the CLV system because the recording density becomes lower toward the outer periphery of the disc.

On the other hand, the CLV system has a larger recording capacity than the CAV system because there is no difference in the recording density between the inner and outer circumferences of the disc, but recording is performed because the rotational speed of the disc having a large inertial mass must be controlled according to the radius of the disc. The playback device is complicated and expensive. Further, there is a drawback that the access time becomes long during reproduction. Therefore, an optical disk device having both advantages, that is, an optical disk device capable of high-speed access and having a large recording capacity has been proposed. For example, the tracks of the optical disc are divided into a plurality of groups according to the distance from the center of rotation, and the CAV method is adopted in each group.
The CLV system is adopted gradually between the groups.
However, in this method, the rotation speed variable control device is still required for both the recording and reproducing devices, and in the case of access to a group far apart from each other, such as the access from the innermost circumference to the outermost circumference, the CLV method is eventually used. There was a drawback that access time was required.

An object of the present invention is to solve these drawbacks and to obtain a signal recording apparatus having a simple structure of the CAV system, a high-speed access function, and a large recording capacity (high recording density) of the CLV system.

[0006]

[Means for Solving the Problems] In order to solve the above problems,
The present invention relates to a rotation driving means for rotating a disc-shaped recording medium having spiral or concentric recording tracks,
A head for writing a signal on the recording track, a memory means for inputting and storing a signal to be written on the recording medium, and a clock generator for outputting a clock having a higher frequency as the radial position of the head with respect to the recording medium is outside. Means and memory control means for outputting the signal to be written stored in the memory means at the clock and inputting the output to the head.

[0007]

In the present invention, the disk-shaped recording medium is rotated at a constant speed, and the signal to be written on the recording medium is temporarily stored in the memory means. A signal on the disk-shaped recording medium is recorded by outputting the signal from the memory means and inputting it to the head with a clock having a frequency corresponding to the radial position of the head (that is, a higher frequency as the radial position is outside). The recording frequency of the signal can be changed according to the radial position.

When pits are formed on all tracks at the same recording density as in the CLV system, when pits are formed at a frequency f on a disc rotating at a revolution number ni at a disc radius ri, f = 2π · ri · ni / 2
d, from which the pit length d is expressed by equation (1). d = π · ri · ni / f (1) Here, the fact that the recording density is constant in all the tracks means that if the same frequency is recorded, the pit length d is irrespective of the disc radius. , The product of the disc radius and the number of revolutions ri ・ n
i must be constant. That is, the disk radius ri
The number of revolutions ni is controlled according to the change of the value to keep the product ri · ni constant.

Next, it will be considered to reproduce the pit length d thus formed by the constant speed rotation, that is, the CAV method. The frequency F obtained by the pit length d on the disk radius r rotating at a constant number of revolutions N is F = 2πrN / 2d, which is expressed by the equation (2). F = πrN / d (2) Equation (1) is substituted into Equation (2) to obtain Equation (3).

F = {(rN) / (ri · ni)} f (3) The formula (3) reproduces the signal of the frequency f recorded by the CLV method at a constant rotation speed N and a disk radius r. It shows the frequency F obtained when Here, ri · ni is a constant that is arbitrarily determined, and is the maximum frequency fma of the signal to be recorded.
The value is determined by the dimension of the pit length d on the disc of x. For example, fmax = 5M
If Hz and d = 1 μm, ri · ni =
It is 1500 mm / sec. In this case, if ri = 50 mm, n
i is 1800 rpm (30 rps). N is also a constant that is arbitrarily determined. When the reproduction is performed by the CAV method (constant rotation speed N), the frequency F is reproduced. Inverse transformation (f = {(ri · ni) / (r
The signal of frequency f is reproduced by performing N)} F).

The present invention is based on the above principle.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to an optical disk still image recording / reproducing apparatus will be described below with reference to FIGS. In FIG. 1, the optical disk 1 is rotated by a spindle motor 2 at a constant rotation speed N, and the rotation speed N is measured by a pulse generator 3. The optical pickup 4 is moved by a slider in the disk radial direction, and its position r is measured by a linear scale 5.

Reference numeral 7 is an arithmetic circuit for converting the frequency of the data according to the equation (3) using the radius r and the rotation speed N, which outputs a voltage or a digital value according to the radius r. Alternatively, it is configured by software. 1
Reference numeral 5 is a variable frequency pulse generating circuit in which the frequency of the pulse output changes depending on the input value. When the output of the arithmetic circuit 7 is a voltage, VCO (voltage control) is used.
And a PD (programmable divider) when the output of the arithmetic circuit 7 is a digital value.

The timing signal detection circuit 6 is the optical head 4
The timing signal is extracted from the signal reproduced by, and the timing pulse is generated. The clock generation circuit 8 divides the pulse from the timing signal detection circuit 6 or the frequency variable pulse generation circuit 15 by switching the switch 18,
It generates a clock.

The output device clock generation circuit 10 generates a clock suitable for the output device 14. The memory control circuit 9 controls input / output of the memory, supplies a clock to the memory, and refreshes the memory. The clock to the memory control circuit 9 is supplied from the clock generation circuit 8 or the clock generation circuit 10, and its selection is performed by the switch 23. The memory 11 has a capacity of one still image and is a dynamic RAM or static RA.
Constructed by M. The output of the memory 11 is the switch 21
According to the configuration, either the laser diode drive circuit 12 or the demodulation circuit 17 can be connected. Input device 13
Is a still image reading device using a TV camera or a linear sensor array (for example, an input unit of a facsimile), and its output is digital.

The modulation circuit 16 performs digital modulation (for example, MFM) suitable for recording in the optical disk device, and further, in order to reproduce the signal from the optical disk without error, the timing based on the error correction signal and the timing pulse from the timing pulse generator 25. A signal is added. Two
Reference numeral 2 denotes a switch that can be switched between recording and reproducing. The demodulation circuit 17 demodulates the digitally modulated signal into a signal that can be input to the output device 14.

The output device 14 is a CRT or a printer. The laser drive circuit 12 drives a laser diode (LD) according to the output of the memory 11 to perform intensity modulation of laser light. The operation of the optical disk device having the above configuration will be described below. First, the recording mode will be described. Switches are connected as shown by the solid line in FIG. That is, switch 2
2 to 16 side, switch 21 to 12 side, switch 18
To the 15 side and the switch 23 to the 8 side.
The still image is converted into an electric signal by the input device 13, and is input to the modulation circuit 16 as a digital signal. It is digitally modulated by the modulation circuit 16 and a timing signal or the like is added based on the timing pulse of frequency f1. FIG. 2A shows the output of the modulation circuit 16. Reference numeral 24 is a timing signal, and 20 is an image signal including an error correction signal.

In order to distinguish the timing signal 24 from the signal 20, for example, a signal in which a fixed number of pulses having a constant duty ratio continue is defined as a timing signal, and (of course, the frequency of the timing signal 24 is f1) is stored in the memory 11. Remember. Move the optical head to the position to be recorded. The position is read by the linear scale 5. Since the disk rotation speed N and ri × ni are constants as described above,
F is obtained by the above equation (3). F in the arithmetic circuit 7
When a voltage corresponding to is output, this output is input to the frequency variable pulse generation circuit 15 and a pulse having a frequency of F is generated. The frequency F is divided by the clock generation circuit 8 to obtain the frequency n.
Get F's clock. Memory 1 with a clock of frequency nF
Then, the intensity of the laser light is modulated by the laser driving circuit 12 and the pits are formed on the optical disc 1 to complete the recording.

Next, the reproduction mode will be described. The reproduction switches 18, 21, 22 are connected to the side shown by the dotted line in FIG. The signal reproduced by the optical pickup is as shown in FIG. 2A when read at the disc radius r. The frequency of the timing signal 24 is F. The timing signal detection circuit 6 extracts the timing signal 24 from the signal shown in FIG. 2A and converts it into the timing pulse 19 as shown in FIG. 2B. The timing pulse 19 is input to the clock generation circuit 8 via the switch 18.
The clock generation circuit 8 performs frequency division and outputs the nF clock shown in FIG. Clock frequency nF
Then, the signal of the optical pickup 4 is stored in the memory 11.

Next, the switch 23 is switched to the output device clock generation circuit 10 side to generate a clock of frequency nf. Here, the switching of the switch 23 is controlled such that after the image signal for one screen is stored in the memory 11, the switching operation is performed from the clock generating circuit 8 to the clock generating circuit 10 for the output device. The fact that the image signal for one screen is stored in the memory 11 can be known by various known means.
For example, it can be known by a signal being stored in a specific address of the memory 11 or by recording a specific signal in advance at the end of one screen and detecting this. The image signal from the memory 11 is clocked at the clock frequency nf.
And is input to the demodulation circuit 17. The demodulation circuit 17 demodulates into a signal capable of operating the output device 14 and outputs it to the output device 14 to obtain a reproduced image.

In this embodiment, for both recording and reproduction,
Although the disk rotation speed is constant, it is of course possible to reproduce the same even with a disk recorded by the conventional CLV method. In the embodiment shown in FIG. 1, the position r of the optical pickup is determined by the linear scale 5. However, when using an optical disc having a guide track, the linear scale 5 need not be used. This is because the track pitch of the disk is kept constant, and if the track address is known, its position can be calculated by, for example, a microcomputer. Further, the frequency variable pulse generating circuit 15 may be composed of a plurality of circuits having different oscillation frequency regions, and the circuit to be used may be selected according to the frequency F.

Further, in the embodiment, the timing signal 24 is added at the time of modulation, but a modulation method capable of self-locking (for example, MFM: Modified Frequency Modulatio).
n, PE: Phase Encoding, etc.), it is not necessary to add the timing signal 24.

[0023]

As described above, according to the present invention, since the recording medium is driven at a constant speed, the structure is simple and high-speed access is possible, and the recording capacity of the recording medium can be increased. Further, a constant recording density can be achieved over all recording tracks.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical disk still image recording / reproducing device to which a signal recording device according to the present invention is applied.

FIG. 2 is a signal waveform diagram at various points in FIG.

[Explanation of symbols]

 1 Optical Disc 2 Spindle Motor 3 Pulse Generator 4 Optical Pickup 5 Linear Scale 7 Arithmetic Circuit 8 Clock Generation Circuit 9 Memory Control Circuit 11 Memory 12 Laser Diode Drive Circuit 15 Frequency Variable Pulse Generation Circuit

Claims (1)

[Claims] 1. A rotary drive means for rotating a disk-shaped recording medium having spiral or concentric recording tracks, a head for writing a signal on the recording track, and a signal to be written on the recording medium. Memory means, clock generating means for outputting a clock having a higher frequency as the position of the head in the radial direction with respect to the recording medium is outside, and outputting the signal to be written stored in the memory means at the clock, A signal recording device, comprising: a memory control unit for inputting the output to the head.