JPS58175142A - Information recording system - Google Patents

Abstract

PURPOSE:To record a large capacity of digital information, by reducing a clock frequency by a specific quantity each time when an optical head is moved for a specific length from the outermost track position of an optical disc in the direction of radius. CONSTITUTION:When information is recorded on an optical disc 1, where the radius of the outermost track is (r), with a constant frequency (f), a capacity C is expressed by C={(r-ri/P}X2piri/a (a, P, and ri are the diameter of a hole for recording of one pit of digital information, the track picth, and the radius of the innermost track of information recording respectively). By this equation, the capacity C is maximum when ri=r/2 is true. When the clock frequency is set to a half of the clock frequency (f) and information is recorded from the part of the radius r/2 to the part of the radius r/4, a maximum capacity of information is recorded there. Hereafter, the clock frequency is changed to 1/2 successively each time when the radius of the track is reduced to 1/2; and thus, the capacity of information recorded when the clock frequency (f) is reduced up to f/8 is 1.33 times as large as the capacity of information which is recorded without changing the clock frequency.

Description

[Detailed description of the invention] The present invention allows digital information to be stored in a highly dense manner on an optical disk. Regarding the method of recording degrees.

Recently, digital information has been recorded by using a laser beam to sequentially thermally drill holes for each bit of digital information on a thin film of metal or chalcogen material on an optical disk.

In this case, the capacity of digital information recorded on concentric or spiral tracks on the optical disk is:
It is determined by the product of the recording capacity per revolution and the number of tracks.

However, if you try to increase the number of tracks, you will have to record information further to the inner circumference, and since the hole diameter for recording each bit of digital information is finite, the recording capacity per track will be limited to the inner track. There will be less. Therefore, when trying to record information on an optical disk at a single clock frequency, if the rotational speed of the optical disk is constant, track 1
The recording capacity per round is determined by the capacity of the innermost track. Furthermore, if the innermost diameter of the trunk is increased, the number of tracks will decrease in an optical disc having a finite outer diameter.

To solve this problem, we made the rotational speed of the optical disc variable.
Alternatively, there is a method of varying the clock frequency, but either method requires changing the speed linearly and continuously, which is difficult to control. The present invention solves the above problems and provides a method for recording a larger amount of digital information on an optical disk whose outermost track diameter is constant.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, on an optical disc 1 whose outermost track has a radius r, digital information is recorded from the outermost track to r/2 at a clock frequency f, and then the radius r
/2 to r/4 with clock frequency f/2,
Furthermore, recording is performed from r/4 to r/8 at a clock frequency of f/4, and each time the radius of the track becomes 1/2, the clock frequency is also reduced to 1/2.

The reason for changing the clock frequency in this way is as follows. That is, when information is recorded at a constant frequency f on an optical disk whose outermost track has a radius r, the capacity C is as follows. Here, a is the diameter of the hole in which one bit of digital information is recorded, P is the track pitch, and ri is the radius of the innermost track in which information is recorded. From the above formula, ri=r
/2, C is maximum. At this time, the clock frequency f is set to f/3, and the radius r/
To record information at maximum capacity from part 2, the radius r/
If you record it at 41, it's fine. Similarly, it is sufficient to change the clock frequency sequentially so that the clock frequency becomes 1/2 every time the radius of the track becomes 1/2.

In this case, compared to the case where the clock frequency is not changed and the outermost periphery is recorded at a single frequency, when the clock frequency is sequentially changed and decreased to f/a, the recorded 8 times are] , 33 times. Incidentally, it is easy to gradually reduce the tarok frequency to 1/2 in this way,
The device itself can be easily configured.

An embodiment for doing this will be explained in detail using the second factor. In the same figure, 1 is an optical disk for recording the digital information shown in FIG. is an address counter, 6 is a clock switching circuit, and 7 is a clock generation circuit.

A rotary encoder or a linear encoder is used for the encoder 4 that detects the position of the movable base 3, and the number of pulses sent from the encoder 4 is determined by the distance r (i.e., the radius of the outermost track) along the radius of the optical disc 1. ), address counter 5 becomes all 1.
11, or 21 bits. moreover,
If the absolute 0 address of the address counter 5 is set when the movable base 3 is at the outermost track position of the optical disk, then when the movable base 3 moves r/2 towards the inner circumference, the n-bit phase output of the address counter 5 Q is reversed.

This state will be explained using FIG. 3 as follows.

That is, when the position of the movable table 3 is from 0 to r/2, the negative signal Qm of Q is used as the clock switching signal, as shown in FIG. At this time, the frequency f generated by the oscillator 8 of the clock generation circuit
a to modulate the light beam. Also, the moving platform 3
/2 to r/4, the signal (b) obtained by ANDing Q, and Q, -0 is used as the clock switching signal, and the frequency is f/2, which is obtained by dividing f by 1/2. head 3
Added to the sadness.

Furthermore, when the moving platform 3 is at r/4 to r/8, a signal (C) obtained by ANDing Q, Q, and Qゎ-2 is used as a clock switching signal, and the frequency is f/8. 4
will be added to the optical head 3a.

In this way, according to the present invention, the recording position on the optical disk is set from the outermost track to 1/2.1/4 of the track radius.
As it moves from 1/8..., the clock frequency changes from f to f/2. f/+, f/8... and 1/
By changing the value by 2''', it is possible to realize a method of recording the digital information of a large-sized hoe with an extremely simple circuit configuration, and the effect is great.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an optical disc according to an embodiment of the present invention in a state in which no information is recorded, FIG. 2 is a block diagram showing the embodiment of the present invention, and FIG. 3 is a time chart of signals of various parts. DESCRIPTION OF SYMBOLS 1... Optical disk, 2... Rotating device, 3... Moving table, 3a... Optical head, 4... Encoder part, 5
... Address counter, 6... Clock switching circuit,
2... Clock generation circuit, 8... Oscillator. Figure

Claims (1)

[Claims] In a digital information recording device using an optical disk,
The optical head is provided with a means for detecting a position of the optical disk in a predetermined radial direction, and a frequency control means for information recording black percentage, and the optical head detects the outermost track radius in the radial direction from the outermost track position of the optical disc. An information recording method characterized in that the clock frequency is sequentially reduced to 1/2 every time the distance of 172 r is traveled.