JPH1040640A - Disc reproducing method and disc reproducing apparatus - Google Patents

Abstract

(57) [Problem] To reproduce an eccentric disk at a high speed by a disk reproducing device generates excessive vibration, which adversely affects the disk reproducing device and other devices installed around the disk reproducing device. The disk comprises: vibration information detecting means for detecting vibration of the apparatus or eccentricity information detecting means for detecting the amount of eccentricity of the disk; and reproduction speed switching control means for controlling the reproduction speed of the disk reproducing apparatus. When excessive vibration occurs at the high speed rotation of, or when the eccentricity information detecting means detects an eccentricity amount equal to or more than a predetermined value, the disk is rotated at a lower speed for reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk reproducing method and apparatus using a disk motor for rotating a disk and an optical pickup capable of high-speed reproduction, and more particularly to vibration of the apparatus accompanying high-speed rotation of an eccentric disk. The present invention relates to a reproducing method and a device suitable for preventing the reproduction.

[0002]

2. Description of the Related Art A CD (compact disk) player has been practically used for a long time, and in recent years, a so-called CD-ROM in which a CD is applied as a personal computer peripheral device has been rapidly spreading.

[0003] The CD-ROM device tends to operate at high speed due to the demand for high-speed data transfer. Recently, 8 times speed has become mainstream, and high speed data transfer at 12 times speed or higher is expected to be essential in the future. .

FIG. 7 is a schematic basic block diagram of a servo system for controlling a disk motor of a conventional disk reproducing apparatus. The information reading section 4 converts information recorded on the disc 1 into an electric signal and inputs the electric signal to the demodulation circuit 6. The demodulation circuit 6 demodulates the electric signal, and the signal processing circuit 7 creates a clock signal from the demodulated signal. The disk motor servo circuit 8 controls the rotation speed of the disk motor 2 via the disk motor drive circuit 3 so that the clock signal and the reference clock signal generated by the reference clock generation circuit 9 become equal.

FIG. 8 shows the relationship between the disk playback speed ratio and the disk rotation speed. CD-ROM
The recording / reproducing method is a CLV method with a constant linear velocity, similarly to the conventional CD player, and the rotation speed changes according to the reproducing position of the disk. CLV is standard 1.2 m / sec at 1 × speed reproduction, and signal recording on the disc is
30 mm to 58 mm, for example, in quadruple speed playback, the radius of the innermost circumference of the disc as shown in the characteristics of FIG.
The rotation speed (frequency) at the position of 25 mm is about 32 Hz, which is the maximum rotation speed during quadruple speed reproduction. Similarly, at the time of 8 × speed reproduction, the maximum rotation speed is about 64 Hz from the characteristic of FIG. 31, and at the time of 12 × speed reproduction, the maximum rotation speed is about 96 Hz from the characteristic of FIG.

[0006]

By the way, as shown in FIG. 9, the disk 1 reproduced by the disk reproducing apparatus has a point 33 which is the center of the disk 1 and the center of the rotational movement.
And a disk in which the point 34 which is the center of gravity of the disk 1 is shifted, that is, a so-called eccentric disk. This is caused by manufacturing factors such as uneven wall pressure of the disk, or by attaching an index label to the disk. This eccentric disk 1 is set at the center point 33.
, A force represented by a vector 35 is generated at the point 33 in the direction of the point 34. Therefore, when the disk reproducing device reproduces the eccentric disk 1, a force represented by the vector 35 acts on the disk motor, and vibration occurs in the disk reproducing device. Further, this force increases in proportion to the square of the rotational speed of the disk. That is, 8
At the time of double speed reproduction, a force four times that at the time of quadruple speed reproduction is generated, and at the time of 12 times speed reproduction, nine times the force at the time of quadruple speed reproduction is generated. Therefore, as the reproducing speed of the disk reproducing device increases, the vibration at the time of reproducing the eccentric disk increases, and this vibration causes a malfunction of the disk reproducing device, and furthermore, the vibration to other devices installed near the disk reproducing device. The negative effects are a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly reliable and safe disk reproducing method and an apparatus for preventing an excessive vibration generated at the time of reproducing an eccentric disk. Is to do.

[0008]

As described above, the vibration of the disk reproducing apparatus at the time of reproducing the eccentric disk increases when the reproducing speed is increased, and is reduced when the reproducing speed is decreased. Therefore, when vibration occurs due to high-speed reproduction of the eccentric disk,
Vibration can be reduced by lowering the reproduction speed.

Therefore, in order to achieve the above object, in the disk reproducing method according to the present invention, information on the vibration of the disk reproducing apparatus is detected, and when the information on the vibration is smaller than a predetermined value, the disk is reproduced at the first reproducing speed. When the information on the vibration is larger than a predetermined value, the disc is reproduced at a second reproduction speed lower than the first reproduction speed.

According to another aspect of the present invention, there is provided a disk reproducing method for detecting information relating to the eccentricity of a disk. When the information relating to the eccentricity is smaller than a predetermined value, the disk is reproduced at a first reproducing speed. When the information on the center of gravity is larger than a predetermined value, the disc is reproduced at a second reproduction speed lower than the first reproduction speed.

In order to achieve the above object, a disk reproducing apparatus according to the present invention comprises: a vibration information detecting means for detecting information relating to vibration of the disk reproducing apparatus; and a disk reproducing speed of a first speed or the first speed. Second lower than speed
Switching control means for controlling switching to the reproduction speed of the disc. When the detection signal of the vibration information detection means is smaller than a predetermined value, the reproduction speed of the disk is set to the first reproduction speed. When the signal is larger than a predetermined value, the reproduction speed is controlled to be the second reproduction speed.

In order to achieve the above object, a disc reproducing apparatus according to the present invention employs an eccentricity information detecting means for detecting information relating to the eccentricity of the disk, which is the amount of displacement of the eccentricity of the disk with respect to the center of the disk. Switching control means for controlling switching to a first reproduction speed or a second reproduction speed lower than the first reproduction speed, and when the detection signal of the eccentricity information detection means is smaller than a predetermined value, the reproduction speed of the disc is reduced. The first reproduction speed is set, and when the detection signal of the gravity center information detecting means is larger than a predetermined value, the reproduction speed is controlled to be the second reproduction speed.

Further, according to the present invention, there is provided display means for displaying a state so that a user can recognize the state when the reproduction speed of the disc is switched from the first reproduction speed to the second reproduction speed. The configuration was adopted.

With this configuration, when it is determined that the amount of eccentricity of the disk is small, or when the vibration does not cause a problem even in high-speed reproduction, high-speed reproduction of, for example, 12 times speed is performed. Is determined to be large, or when vibration occurs during high-speed playback, the playback speed is controlled from the 12-fold speed to, for example, 8-fold speed, or to 4-fold speed according to the amount of eccentricity of the disk by the control of the switching control means. The playback speed of the disc can be automatically switched to a playback speed or a playback speed at which vibration does not cause a problem.

[0015]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram of a disk reproducing apparatus according to a first embodiment of the present invention.

In FIG. 1, 1 is a disk, 2 is a disk motor, 3 is a disk motor drive circuit, 4 is an information reading section including moving means, and 5 is a movement for controlling and driving the moving means of the information reading section 4. Means driving circuit, 6 is a demodulation circuit for demodulating a signal from the information reading section 4, 7 is a signal processing circuit, 8 is a disk motor servo circuit, 9 is a reference clock generation circuit, 10 is an audio circuit, 11 is an audio output terminal, 12 is a CD-ROM decoder, 13 is a CD-ROM decoder.
ROM signal output terminal, 14 is a vibration detecting means for detecting the vibration of the disk reproducing apparatus, 15 is a vibration identifying means, 16 is a frequency dividing circuit for dividing the reference clock signal output from the reference clock generating circuit 9, and the frequency dividing circuit Reproduction speed switching control means including a control circuit for controlling the frequency division ratio of the reproduction speed. Although not directly related to the gist of the present invention, FIG. 1 also shows an audio circuit, a CD-ROM decoder, and the like.

When an eccentric disk whose center of gravity is displaced from the center of gravity of the disk is reproduced at a high speed of, for example, 12 times by the disk reproducing apparatus, vibrations occur in the disk reproducing apparatus. The vibration affects the information reading unit 4. If the influence is within a range controllable by the moving unit control circuit 5 and the disk motor control circuit 8, the information reading unit 4 converts the information of the disc 1 into an electric signal. The audio output terminal 11 or the CD-ROM signal output terminal 1 is subjected to signal processing by the demodulation circuit 6 and the signal processing circuit 7, the audio circuit 10 or the CD-ROM decoder 12.
3 outputs a signal. However, when the vibration is large, the operation of the disc reproducing apparatus may become impossible.

The vibration detecting means 14 detects the vibration of the disk reproducing apparatus and outputs a signal corresponding to the vibration intensity. The vibration detecting means 14 is configured using, for example, an impact voltage conversion element or the like. The vibration discriminating means 15 discriminates the output signal of the vibration detecting means 14, and when the output signal exceeds a predetermined value, judges that the vibration of the disc reproducing apparatus is large, and issues a control signal for reducing the reproducing speed to a reproducing speed switching control. Means 1
Output to 6. The reproduction speed switching control means 16 generates a frequency-divided clock signal obtained by dividing the reference clock signal output from the reference clock generation circuit 9 by a frequency division ratio corresponding to the control signal from the vibration identification means 15, and generates a disk motor servo circuit. 8 is output. The disk motor servo circuit 8 controls the rotation speed of the disk motor 2 via the disk motor drive circuit 3 so that the divided clock signal and the clock signal output from the signal processing circuit 7 become equal. Therefore, the rotation speed of the disk motor 2 decreases in accordance with the control signal output from the vibration identification means 15. Here, the force at the time of rotation of the eccentric disk, which causes vibration of the disk reproducing device, is proportional to the square of the rotation speed as described above. Therefore, when the reproducing speed of the eccentric disk is reduced from 12 × speed to 4 × speed, the rotation speed becomes 1/3, and the force causing the vibration becomes 1/9, and the vibration of the disk reproducing device can be reduced.

In addition, instead of the vibration detecting means 14, the moving means driving circuit 5 uses a control signal output for controlling the moving means of the information reading section 4 to detect information relating to vibration of the disk reproducing apparatus. An example is shown in FIG.
In FIG. 2, reference numeral 17 denotes a reference signal generating means for outputting a reference signal which is a signal equivalent to a control signal output by the moving means driving circuit 5 when reproducing an ideal disc which does not include a center of gravity or the like, and 18 denotes a comparing means. And the other parts denoted by the same reference numerals as those in FIG. 1 indicate the same blocks. When vibration occurs in the disk reproducing device due to the high-speed reproduction of the eccentric disk, a disturbance corresponding to the magnitude of the vibration occurs in the control signal output from the moving means driving circuit 5. Reference signal generating means 1
Reference numeral 7 outputs a control signal output by the moving means driving circuit 5 when an ideal disk not including the center of gravity or the like is reproduced at a high speed, that is, a reference signal which is equivalent to a control signal not including the disturbance. Therefore, the reference signal and the control signal including the disturbance due to the vibration are compared by the comparing means 18 to detect the magnitude of the disturbance of the control signal. Therefore, it is possible to detect information related to the vibration of the disk reproducing apparatus by using the control signal output from the moving means driving circuit 5.

Further, since the control signal disturbance due to the vibration also occurs in the control signal output from the disk motor servo circuit 8 of FIG. 1, the control signal output from the disk motor servo circuit 8 relates to the vibration of the disk reproducing apparatus. It is also possible to detect information.

In the first embodiment, the disk is once reproduced at a high speed, and it is detected that excessive vibration due to the eccentricity of the disk has occurred. Then, the reproduction speed of the disk is reduced to reduce the vibration. It is. However, in order to safely operate the disk playback device, the amount of eccentricity of the disk is detected before playing the disk, and a disk with a large amount of eccentricity is not played at high speed from the beginning, and vibration is generated. It is desirable not to let them.

FIG. 3 shows a second embodiment of the present invention in which this point is taken into consideration.

In FIG. 3, reference numeral 19 denotes an eccentricity detecting means for detecting the amount of eccentricity of the disk 1 and outputting a signal corresponding to the amount of eccentricity. Reference numeral 20 denotes an eccentricity identifying means for identifying an output signal of the eccentricity detecting means 19. And the other parts denoted by the same reference numerals as those in FIG. 1 indicate the same blocks.

The eccentricity discriminating means 20 is an eccentricity detecting means 19.
Is larger than a predetermined value, it is determined that the amount of eccentricity of the disk 1 is large, and a control signal for reducing the reproduction speed is output. The reproduction speed switching control means 16 sets the frequency division ratio of the reference clock signal output from the reference clock generation circuit 9 according to the control signal from the eccentricity discrimination means 20.

Therefore, the disc reproducing apparatus of the second embodiment does not perform high-speed reproduction on the disc 1 when the discrimination unit 20 identifies that the disc 1 has a large amount of discrepancy.

That is, when the amount of eccentricity of the disk 1 is large, the reproducing speed is set to a low speed in advance, so that the eccentric disk is not reproduced at a high speed such as 12 times speed, and the occurrence of vibration is prevented beforehand. This can be prevented.

The eccentricity discriminating means 19 is realized, for example, by the configuration shown in FIG. In FIG. 4, reference numerals 21 to 24 denote weight detecting means for converting weight into voltage, reference numerals 25 and 26 denote subtracting means, reference numeral 27 denotes an adding means, and other parts denoted by the same reference numerals as those in FIG. As shown in FIG. 5, the weight detecting means 21 to 24 are arranged on a straight line orthogonal to the center of the disk 1 and at the same distance from the center of the disk 1. When the disk 1 is placed on the weight detecting means 21 to 24, the weight of the disk 1 is distributed to and added to the weight detecting means 21 to 24, and the weight detecting means 21 to 24 subtract the voltage corresponding to the added weight. 25 and 26. Weight detecting means 21 to 24
5 are disposed at the positions shown in FIG. 5, the weight is applied to the weight detecting means 21 to 24 when the amount of eccentricity of the disk 1 is almost zero. There is a difference in the weight applied to the means 21 to 24. The subtraction unit 25 detects the voltage difference output from the weight detection units 21 and 23, and the subtraction unit 26 detects the voltage difference output from the weight detection units 22 and 24. That is, the subtraction means 25 detects the amount of eccentricity of the disk 1 in the linear direction in which the weight detection means 21 and 23 are arranged, and
Numeral 6 detects the amount of eccentricity of the disk 1 in the linear direction in which the weight detecting means 22 and 24 are arranged. The output voltages of the subtracting means 25 and 26 are added by the adding means 27 and output to the eccentricity discriminating means 20. Therefore, the voltage output from the adding means 27 corresponds to the amount of eccentricity of the disk 1, and the amount of eccentricity of the disk 1 can be detected by the configuration of FIG. In the configuration of FIG. 4, four weight detecting means are used. However, if the number of weight detecting means is three or more, the amount of eccentricity of the disk 1 can be detected by the same operation principle.

Further, information relating to the eccentricity of the disk 1 is detected by using a control signal output by the moving means driving circuit 5 to control the movability of the information reading section 4 instead of the eccentricity detecting means 19 of FIG. FIG. 6 shows an embodiment of this means. In FIG. 6, reference numerals 28 and 29 denote control amount storage means for storing the control amounts of the moving means of the information reading unit 4, and other parts denoted by the same reference numerals as those in FIG. 3 indicate the same blocks.
As described in the first embodiment, when the eccentric disk 1 is reproduced at a high speed, a vibration is generated in the disk reproducing apparatus, and the moving means driving circuit 5 controls the moving means of the information reading section 4 according to the vibration. I do.

The amount of this control changes according to the square of the reproduction speed of the eccentric disk 1 and the amount of eccentricity of the eccentric disk 1. The control amount storage unit 28 stores the control amount of the moving unit of the information reading unit 4 when the disk 1 is reproduced at a low speed, for example, 1 × speed, and the control amount storage unit 29 stores the disk 1
The control amount of the moving means of the information reading unit 4 when the data is reproduced at such a high speed that vibration does not become a problem, for example, at a quadruple speed, is stored. Here, when the amount of eccentricity of the disk 1 is almost zero, the control amounts stored in the control amount storage means 28 and 29 are equal, but when the disk 1 is an eccentric disk,
The control amount at the time of quadruple speed reproduction stored in the control amount storage means 29 becomes larger than the control amount at the time of 1 × speed reproduction stored in the control amount storage means. Therefore, the control amount storage means 28, 29
The amount of eccentricity of the disk 1 can be detected by comparing the control amount stored in the disk 1 with the comparing means 18.

Further, since the difference in the control amount due to the reproduction speed also occurs in the control signal output from the disk motor servo circuit 8, information on the amount of eccentricity of the disk 1 is detected from the control signal output from the disk motor servo circuit 8. It is also possible.

[0031]

As described above, according to the present invention, the vibration of the disk reproducing apparatus or the amount of eccentricity of the disk is automatically detected, and the reproducing speed is controlled accordingly. In other words, when an eccentric disk is reproduced at a high speed of 12 times speed and excessive vibration occurs, the reproduction speed is increased from 12 times speed to, for example, 8 times speed or 6 times speed so that the vibration is not a problem. Automatically switched to. If the amount of eccentricity of the disk is detected in advance and it is determined that the amount of eccentricity is large, the reproducing speed of the disk is increased from 12 times to, for example, 8 times speed, or to 6 times speed, to a reproducing speed corresponding to the amount of eccentricity. Playback after automatic switching. Therefore, it is possible to prevent a malfunction of the disk reproducing apparatus due to the vibration generated at the time of high-speed reproduction of the eccentric disk, and also to prevent adverse effects on other apparatuses installed near the disk reproducing apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram of a disc reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a vibration detection unit that detects information regarding a vibration of the disc reproducing apparatus from information regarding an operation amount of a moving unit.

FIG. 3 is a block diagram of a disc reproducing apparatus according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an eccentricity detecting means 19;

FIG. 5 is a diagram illustrating an installation position of a weight detection unit.

FIG. 6 is a block diagram showing a configuration of an eccentricity detecting means for detecting information on an eccentricity of a disk from information on an operation amount of a moving means.

FIG. 7 is a schematic basic block diagram of a servo system for controlling a disk motor of a conventional disk reproducing apparatus.

FIG. 8 is a diagram showing the relationship between the disk rotation speed and the disk reproduction speed ratio.

FIG. 9 is a diagram showing a force generated when the eccentric disk rotates.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... disk, 2 ... disk motor, 3 ... disk motor drive circuit, 4 ... information reading part, 5 ... moving means drive circuit, 6 ... demodulation circuit, 7 ... signal processing circuit, 8 ... disk motor servo circuit, 9 ... standard Clock generation circuit, 10 audio circuit, 11 audio output terminal, 12 CD
-ROM decoder, 13 ... CD-ROM signal output terminal,
14: vibration detection means, 15: vibration identification means, 16: reproduction speed switching control means, 17: reference signal generation means, 18
... Comparing means, 19: Off-center detecting means, 20: Off-center identifying means, 21 to 24: Weight detecting means, 25: Subtracting means,
26: Subtraction means, 27: Addition means, 28: Control amount storage means, 29: Control amount storage means, 30: Rotation speed during quadruple speed reproduction, 31 ... Rotation speed during reproduction at 8x speed, 32: Rotation speed during reproduction at 12x speed , 33: Center point, 34: Center of gravity, 35: Vector representing force generated during rotation.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Narita, Director Ichicho Narita 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref.Hitachi Hitachi, Ltd. (292) Inventor Koichi Ishibashi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref. Hitachi Information Systems, Ltd.

Claims (9)

[Claims] 1. A disk motor drive circuit for driving a disk motor for rotating a disk, and an information reading unit configured to be movable from an inner peripheral side of the disk to an outer peripheral side or from an outer peripheral side of the disk to an inner peripheral side for reading information on the disk. A disc reproducing apparatus comprising: a disc reproducing apparatus that reproduces a disc by setting a reproducing speed of a disc to a first speed when information about vibration of the disc reproducing apparatus is smaller than a predetermined value; When the information is larger than a predetermined value, the disk is reproduced at a second reproduction speed lower than the first reproduction speed. 2. The apparatus according to claim 1, wherein the information relating to the vibration of the disk reproducing apparatus is obtained from information relating to an operation amount of a vibration detecting means provided inside or outside the disk reproducing apparatus and a moving means for controlling the movement of the information reading unit. At least one of means for detecting information relating to vibration of the apparatus, and means for detecting information relating to vibration of the disk reproducing apparatus from information relating to an operation amount of the disk motor drive circuit.
2. The disk reproducing method according to claim 1, comprising: 3. A disk motor drive circuit for driving a disk motor for rotating a disk, and an information reading section configured to be movable from the inner circumference of the disk to the outer circumference or from the outer circumference of the disk to the inner circumference to read information on the disk. A disc reproducing apparatus comprising: a disc reproducing device that sets a reproducing speed of the disc to a first speed when the information on the eccentricity of the disc, which is a deviation amount of the center of gravity from the center of the disc, is smaller than a predetermined value. When the reproduction is performed and the information on the eccentricity of the disc is larger than a predetermined value,
A method for reproducing a disk, wherein the reproduction speed of the disk is set to a second speed lower than the first speed to reproduce the disk. 4. The information relating to the eccentricity of the disk is obtained from information relating to an operation amount of a eccentricity detecting means provided inside or outside the disk reproducing device and a moving means for controlling the movement of the information reading unit. 4. The apparatus according to claim 3, further comprising at least one of means for detecting information relating to an eccentricity and means for detecting information relating to an eccentricity of said disk from information relating to an operation amount of said disk motor drive circuit. Disc playback method. 5. A disk motor drive circuit for driving a disk motor for rotating a disk, and an information reading section configured to be movable from the inner circumference of the disk to the outer circumference or from the outer circumference of the disk to the inner circumference to read information on the disk. A disk reproducing apparatus comprising: a vibration information detecting means for detecting information on vibration of the disk reproducing apparatus; and a reproducing speed switching control means for controlling to switch a reproducing speed of the disk reproducing apparatus. When the information is smaller than the predetermined value, the reproduction speed of the disk reproducing device is set to the first speed to reproduce the disk, and when the information on the vibration of the disk reproducing device is larger than the predetermined value, the reproduction of the disk reproducing device is performed. The reproduction of the disc is performed with the reproduction speed set to a second speed lower than the first speed. Disk playback apparatus according to. 6. The disk reproducing apparatus according to claim 1, wherein said vibration information detecting means includes a vibration detecting means provided inside or outside said disk reproducing apparatus, and a vibration of said disk reproducing apparatus based on an operation amount of a moving means for controlling a movement of said information reading section. 6. The apparatus according to claim 5, further comprising: at least one of a unit for detecting information regarding the disk drive unit and a unit for detecting information regarding a vibration of the disk reproducing apparatus from information regarding an operation amount of the disk motor drive circuit. Disc playback device. 7. A disk motor drive circuit for driving a disk motor for rotating a disk, and an information reading section configured to be movable from the inner circumference side of the disk to the outer circumference side or from the outer circumference side of the disk to the inner circumference side for reading information of the disk. A disc reproducing apparatus comprising: a disc-center information detecting means for detecting information relating to a disc center of gravity which is an amount of displacement of a center of gravity with respect to the center of the disc; and a reproducing speed switching control for controlling a reproducing speed of the disc reproducing apparatus. Means, when the information on the eccentricity of the disc is smaller than a predetermined value, the disc is reproduced by setting the reproduction speed of the disc reproducing apparatus to the first speed, and the information on the eccentricity of the disc is more than the predetermined value. If the speed is higher, the playback speed of the disk playback device is set to a second speed lower than the first speed, and Disk reproducing apparatus, characterized in that for reproducing the disk. 8. The discrepancy information detecting means includes a discrepancy detecting means provided inside or outside the disc reproducing apparatus, and information on an operation amount of a moving means for controlling a movement of the information reading section. The apparatus further includes at least one of a unit for detecting information about a center, and a unit for detecting information about an eccentricity of the disk from information about an operation amount of the disk motor drive circuit.
The disk reproducing device according to claim 7. 9. The apparatus according to claim 5, further comprising display means for displaying a state when the reproduction speed of said disk is switched from said first speed to said second speed. A disk playback device according to any one of the above.