JPS62262270A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the bit density and to simplify the control of a write frequency increasing the frequency of a write clock signal as the number of cylinders to which a head in placed becomes fewer (as the head is closer to the outermost circumference of a disk). CONSTITUTION:A register 1 records cylinder information representing the cylinder location via a system bus 20, and a filter/oscillator control circuit 2 outputs a control signal based on the cylinder information from the register 1. A filter circuit 6 changes stepwise the frequency characteristic of the filter based on a control signal from the circuit 2 and a control oscillator 9 outputs a write clock signal changed stepwise. That is, when the head is arranged to a location close to the outermost circumference of the disk 4, since the number of cylinders with a head placed becomes fewer, the frequency of the write clock signal is increased. Thus, the bit-density at all cylinder positions is made to a prescribed value and the storage capacity is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information recording/reproducing device in which the writing frequency changes depending on the recording position of a one-rotation recording medium.

[Prior Art] Conventional disk-type storage devices perform writing based on the bit density at the innermost circumference of the disk, thereby increasing the reliability of the device. In other words, in this method, the rotational speed of the disk and the frequency of the write clock are set so that the bit density on the inner circumference of the disk can be maintained at a predetermined value. Writing is performed while keeping the rotational speed of the disk and the frequency of the write clock constant.

Therefore, even on the outer periphery where writing density can be increased, data is written at the same rotational speed and frequency as when writing on the inner periphery.

Because of this, the actual disk capacity is much less than what it could theoretically have.

FIG. 5 is a chart showing the relationship between cylinder and bit density in a conventional disk storage device.

In general, the bit density of data is determined by the resolution of the head, etc., and is originally the same everywhere on the disk, but since the disk rotates at a constant angular velocity and the writing frequency is constant, the bit density of the data is determined by the resolution of the head. The bit density gradually decreases toward the outer periphery.

Here, cylinder C2 on the inner circumference (the one with the largest number of cylinders)
In Figure 1, when the bit density is d2, the density in the cylinder cl on the outer periphery (the one with the least number of cylinders) decreases to dl, resulting in a capacity loss. The area surrounded by abc (hatched area) is the amount of loss.

Now, if the bit density at all cylinder positions is set to d2, the storage capacity will increase only in the portion surrounded by abc.

In order to do this, conventionally, the density is made constant by keeping the linear velocity per rotation constant depending on the position of the head.

However, the conventional example described above has a problem in that control of the rotational linear velocity becomes complicated.

[Object of the Invention] The present invention has been made by focusing on the problems of the above-mentioned prior art, and provides an information recording and reproducing device that can improve bit density and simplify control of writing frequency. The purpose is to

[Embodiments of the invention] FIG. 1 is a block diagram showing one embodiment of the present invention.

Register l is connected to cylinder position I via system bus 20.
! This is to record cylinder information indicating (head position W1). The filter/oscillator control circuit 2 outputs a control signal based on cylinder information from register l.

The filter circuit 6 changes the frequency characteristics of the filter in steps based on a control signal from the filter/oscillator control circuit 2. The voltage controlled oscillator 9 outputs a write clock signal whose input voltage versus output frequency characteristic changes stepwise based on a control signal from the filter oscillator control circuit 2.

In other words, the smaller the number of cylinders in which the head is located (the closer the head is to the outermost circumference of the disk), the higher the frequency of the write clock signal becomes.

The relationship between the number of cylinders and the frequency of the write clock signal is
This is shown in FIG.

The disk control device 3 sends the write clock signal to the disk 4 and also performs general control of the disk (disc-shaped recording medium) 4.

The phase comparison circuit 7 synchronizes the read signal read from the disk storage device 4 with the output signal (window signal) of the voltage controlled oscillator 9, and also performs peak shift (shift from the normal bit position). ).

Note that an amplifier $5 and a waveform shaping circuit 8 are provided.

Next, the write operation of the above embodiment will be explained.

First, before writing predetermined information to the disk 4, cylinder position information indicating the cylinder position where the head is located at that time is set in the register l via the system bus lO.

When the cylinder position information is set in the register 1, this data is sent to the filter circuit 6 and the voltage controlled oscillator 9 via the filter oscillation control circuit 2. Then, a write clock signal with a frequency corresponding to the cylinder position information is output from the voltage controlled oscillator 9 (details will be described later).In other words, if the head is located near the outermost circumference of the disk 4, Since the number of cylinders in which the is located is small, the frequency of the write clock signal becomes high. This frequency is higher than the frequency of the clock signal when the disk 21 is located at the innermost circumference of the disk 4.

For example, if the rotational speed of the disk 4 is B (7 seconds of rotation), the radius of the innermost cylinder C2 is r2, and the radius of the outermost cylinder C1 is r2 (Fig. 6), one bit of the disk 4 Let the length be A. In this case, the frequency f of the write clock signal in the outermost cylinder CI
1 is.

fl=2ew*rlsB/A (Hz), and the frequency f of the write clock signal in the innermost cylinder C2
2 is.

It is sufficient to set f 2 = 2 * πa r2 m B/A (H2).

The frequency of the clock signal in the cylinders between the outermost cylinder CL and the innermost cylinder C2 may be changed in steps by proportionally distributing the frequency according to the number of cylinders existing therebetween.

In this way, the bit density at all cylinder positions can be set to d2, and in this case, only the part surrounded by abc (the part surrounded by diagonal lines) shown in FIG.
Memory capacity increases.

The radius r1 of the outermost cylinder C1 and the innermost cylinder C
The larger the difference between radius r2 and radius r2, the greater the amount of increase in disk capacity. Further, in the above embodiment, since the control amount of the rotation system is not changed, stable operation can be ensured. Furthermore, the responsiveness is higher than when changing the control amount of the rotation system.

Further, in order to simplify the circuit configuration, the number of steps in the frequency change of the claw 2 signal may be made smaller than the number of cylinders, and even in this case, the disk capacity can be increased.

Next, the reading operation of the above embodiment will be explained.

First, before reading predetermined information from the disk storage device 4, cylinder information (the number of cylinders in which the head is located) is set in the register l via the system bus 20.

Then, when the number of cylinders is set in register l,
This data is sent via filter/oscillator control circuit 2 to filter circuit 6 and voltage controlled oscillator 9. In the filter circuit 6, one of the filter characteristics (shown in FIG. 2) is selected in response to a control signal from the control circuit 2. On the other hand, in the voltage control oscillation circuit 9, the input-to-output oscillation characteristic (third
(shown in the figure) is selected.

That is, the filter 6 has a plurality of characteristics, as shown in FIG. 2, and one of these characteristics is selected depending on the cylinder position (number of cylinders) of the head. The smaller the number of cylinders (the closer to the outer circumference of the disk), the higher the cutoff frequency becomes.

Further, the voltage controlled oscillator 9 has a plurality of characteristics, as shown in FIG. 3, and one of these characteristics is selected depending on the cylinder position ff1 (number of cylinders). For the same input voltage, the smaller the number of cylinders (closer to the outer circumference of the disk), the lower the frequency signal will be output.

In other words, in FIG. 3, if the inner circumference cylinder is N, the corresponding frequency characteristics are the lowest frequency fL, the highest frequency fH, and the center frequency fT, and the voltage controlled oscillator 9 having these characteristics is initially set. be done. This characteristic varies depending on the cylinder position of the head, l, 2, etc.
, N.

Now, when the disk control device 3 performs read control on the disk storage device 4, a read signal is output from the disk device 214 and sent to the waveform shaping circuit 8. This waveform shaping circuit 8 shapes the waveform of the signal into a signal suitable for the phase comparator circuit 7. This output signal is phase-compared with the output signal of the two-voltage controlled oscillator 9 in the first phase comparison circuit "i!17".The resulting phase difference is sent to the filter circuit 6 as an error signal.

The error signal is filtered and amplified by the amplifier 5 according to a characteristic selected from among the plurality of characteristics shown in FIG. 2, depending on the number of cylinders at that time. This amplified signal is sent to voltage controlled oscillator 9. Depending on the number of cylinders at that time.

The voltage frequency is converted according to a characteristic selected from a plurality of characteristics shown in FIG.

The phase of this converted signal is compared with the output signal of the waveform shaping circuit 8, and at the same time, it is output as a window signal to the disk controller. ! Sent to 3. Then, the PLL circuit (
Serial-to-parallel conversion is performed based on the normalized window signal by a voltage controlled oscillator 9, a filter circuit 6, and a phase comparator circuit 7.

[Effects of the Invention] According to the present invention, there is an effect that bit density can be improved and writing frequency can be easily controlled.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing the characteristics of the filter circuit in the above embodiment. FIG. 3 is a diagram showing the characteristics of the voltage controlled oscillator in the above embodiment. FIG. 4 is a chart showing the relationship between cylinder position and write clock frequency in the above embodiment. FIG. 5 is a chart showing the relationship between cylinder position and recording density in a conventional example. FIG. 6 is a diagram showing the radius of each cylinder on the disk. 1... Cylinder position register, 4... Disc-shaped storage device, 6... Filter circuit, 7... Phase comparison circuit, □ 9... Voltage controlled oscillator. Patent applicant Canon Co., Ltd. Agent Arata Yokubo - Figure 2 Figure 3

Claims (1)

[Claims] It is characterized by having a filter device whose frequency characteristic changes stepwise according to the recording position of a rotating recording medium, and a voltage controlled oscillator whose input voltage vs. output frequency characteristic changes stepwise according to the recording position. Information recording and reproducing device.