JPH0944980A - Dirt detecting device and reproducing device for minidisk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a minidisk reproducing device which detects dirt affecting reproduction and displays that a sound-skipping and a reproduction impossibility are caused by dirt to the outside by using a dirt discriminating circuit. SOLUTION: The read part 10 of an optical pickup reads out data by following to the track of a minidisk. A servo control circuit 53 controls the operation of the read part 10 and also outputs an off-track signal when the optical pickup is deviated from a track which the pickup following, and a stylus-skipping is generated. A stylus-skipping address storage part 18 stores the address information on position where a previous off-track signal was outputted, and a judging circuit 20 judges whether the stylus-skipping is caused by the dirt of the surface of the minidisk by performing the comparison of the address information of a position where a present off-track signal was outputted based on the position in the storage part. When the address difference between the previous position and the present position is equivalent to the length equivalent to the one rotation or the several rotations of the track, judging circuit 20 judges that the surface of the minidisk is soiled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mini disc (M
The present invention relates to a dirt detection device of D), and more particularly, to a dirt detection device that detects dirt that causes needle skipping when an optical pickup comes off a track. Further, the present invention relates to a mini disk reproducing device, and more particularly to a mini disk reproducing device for detecting stains that cause needle jump and displaying and outputting an abnormality.

In the present specification, the "needle jump" means that the spot of the optical pickup deviates from the track being followed (traced). CD (compact disc)
Generally speaking, it is called “sound skip”, but in MD, the sound is not skipped, so it is called “needle skip” here.

[0003]

2. Description of the Related Art FIG. 21 shows the structure of a conventional mini disc reproducing apparatus (MD player).

The optical pickup 51 reads a recording signal on the disk 50C by reflecting laser light. The optical pickup 51 moves to an arbitrary position on the disk 50C based on the drive control by the servo control circuit 53 (hereinafter referred to as access).

The RF amplifier 52 amplifies the signal read by the optical pickup 51 to an appropriate level as an electric signal. The MD 50 may be an optical disk or a magneto-optical disk. Since the optical pickup 51 performs switching, the output of the RF amplifier has the same characteristics on either recording medium.

The servo control circuit 53 includes an optical pickup 5
1 is made to follow the signal train on the disk 50C, and the optical pickup 5 is instructed by the system controller 59.
1 is moved to the target position on the disk 50C. Also,
When the optical pickup 51 causes the needle jump, an off-track signal (OFTRK signal) is output to the system controller 59.

The EFM and ACIRC decoder 54 are MD
EFM decoding that is the modulation of the recording data of 50 and ACIRC decoding that is the error correction are performed.

The memory controller 55 is a disk 50.
The data read from C is shockproof memory 5
Write to 6. Also, the data is read from the memory 56. As described above, by using the memory 56 as a buffer at the time of reproduction, it is possible to eliminate skipping due to vibration and edit a recorded MD.

As the shock proof memory 56, a 4-Mbit DRAM is used here. 4 Mbi
It is possible to buffer a reproduction time of about 12 seconds at t.

The ATRAC decoder 57 decodes and encodes ATRAC, which is a MD data compression method. After this decoding, 16-bit linear PCM
It becomes audio data.

The 16-bit A / D converter converts the analog signal of the audio input during recording into a 16-bit linear PCM.
Convert to audio data.

The 16-bit D / A converter 58 converts 16-bit linear PCM audio data into an analog signal during reproduction.

The system controller 59 sends an instruction to each block of what is requested by key input and realizes it, and displays necessary information. Here, it consists of a microcomputer and software.

Next, a conventional reproducing operation will be described with reference to FIG.

Since the mini disk reproducing apparatus compresses and records data, the optical pickup 51 has a much higher rate (1.4 [mbit / s]) than the data rate (0.3 [mbit / s]) required for reproduction. [Mbit / s]) is reading data from the disk 50C. Therefore, the data is temporarily stored in the shock proof memory 56, and this is used as a buffer to read the data from the memory 56 for reproduction. As a result, processing such as eliminating skipping due to vibration and editing recorded MDs is performed.

That is, the data is the shock proof memory 5
If the data is stored in No. 6, even if the optical pickup 51 is deviated from the disk 50C due to vibration and cannot read the data, the data stored in the shock proof memory 56 can be continuously reproduced. That is, as long as the data in the shock proof 56 is not empty, the voice can be continuously output.

From the disk 50C to 1.4 [Mbit /
Since the signal read in [s] is a compressed signal, only 0.3 [Mbit / s] is required to decode it. For this reason, as shown in FIG.
The signal of is read out intermittently. In normal reproduction, when the maximum amount is stored in the shock proof memory 56, the reading from the disk 50C is awaited. The amount of data from the shock proof memory 56 decreases due to the reproduction, and when the amount becomes less than a certain amount, the maximum amount is read again.

When the spot of the optical pickup deviates from the traced track due to vibration or the like during normal reproduction (hereinafter, this is referred to as needle jump), the needle jump location is searched as shown in FIG. During this search, the music in the shock proof memory 56 continues to be reproduced by the data.

As described above, since the music is reproduced without interruption even if the staple skip has actually occurred, the user does not notice that the staple skip has occurred.

If the disc 50C is lightly soiled and can be reproduced by another trace, the shock proof memory 56 does not cause skipping.

[0021]

However, in the above-described conventional example, depending on the degree (size) of dirt, the same location may be repeatedly stapled, the shock proof memory may become empty, and the reproduced sound may be interrupted. In the case of more extreme dirt, it becomes impossible to continue the reproduction.

In the conventional MD player, when the reproduction cannot be continued due to the extreme dirt, an error display for notifying an abnormality is displayed. However, the MD player cannot detect whether the reproduction is impossible due to stains or due to another cause, and there is no choice but to externally display that reproduction is impossible.

According to the standard from the beginning, in the MD, the disc is housed in the cartridge and the signal is read from the disc by opening the shutter in the MD player. Therefore, in normal handling, the disc surface is not touched. Does not easily get dirty. However, if the shutter opens or becomes dirty for some reason, the disk surface inside the cartridge cannot be seen by the eye, and the user does not notice the dirt.

In the case of a CD, when a skipped stitch occurs, it is directly reproduced as a skipped sound. Therefore, in the case of a skipped stitch due to stains, the same portion is repeatedly reproduced, or a skipped sound occurs periodically, so that the user skips. Can recognize that the stain has occurred on the hearing.

However, in the case of MD, since the needle skip does not appear directly in the reproduced sound due to the shock proof memory, C
A characteristic reproduced sound like D does not occur. Therefore, the user does not auditorily recognize the dirt.

Therefore, the conventional MD player has a disadvantage that it is not possible to determine whether the cause of the skipped sound or the reproduction failure is due to dirt, vibration, or another reason.

Moreover, there is a disadvantage that the user of the MD player has no means for confirming whether the MD disc has dirt that causes needle skipping.

[0028]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mini disk dirt detecting device which can improve the disadvantages of the prior art and can detect the dirt on the mini disk which affects the reproduction. . Further, the present invention provides a mini disc reproducing apparatus capable of detecting stains on a mini disc which influences reproduction and displaying externally the fact that the stain is the cause when skipping sound or reproduction becomes impossible. Also for that purpose.

[0029]

Therefore, in the present invention, as a first means, a reading section having an optical pickup for reading the data recorded on the mini disk by following the track of the mini disk, and the reading section. And a servo control circuit that outputs an off-track signal when the optical pickup is out of the track being followed and a needle jump occurs. Further, based on the address information of the position where the previous off-track signal was output and the address information of the position where the off-track signal was output this time from the predetermined needle-skip address storage unit, these needle skips are It is provided with a stain determination circuit for determining whether or not it is due to stains on the disk surface, and a staple jump address storage unit for storing address information of the current stitch skip after the determination by the stain determination circuit is completed. Moreover, if the address difference between the address of the last stitch jumped position and the address of the needle stitch skipped position this time corresponds to the length of one or several rotations of the track, the surface of the mini disk is soiled. A stain determination unit that determines that the stain is present is provided.

According to the first means specified by these matters, the reading section includes an optical pickup, a spindle motor for rotating the mini disc at a constant linear velocity, and a feed motor for driving the optical pickup in the radial direction of the mini disc. And consists of reading the data recorded on the mini disk. The servo control circuit drives and controls the feed motor and the spindle motor to cause the optical pickup to follow the track of the mini disk, and outputs an off-track signal when it is out of the track. At this time, since it is necessary to read again from a position off the track, the address information when the off-track signal is output is held.

The needle jump address storage unit stores the address where the needle jump occurs when such needle jump occurs. This stapling address is updated or erased when stapling occurs again or when the mini disk is replaced. Here, an example is given in which the needle skipping occurs once and the address information is stored in the staple jump address storage unit. Here, this address information is referred to as "address information that caused the last stitch skip (the off-track signal was output)." The “address difference” is the difference in sector units from the position where the last needle jumped position to the position where the current needle jumped position is, and indicates the data amount of the interval.

The dirt determination circuit determines whether or not the surface of the mini disk at the needle jump position is dirty based on the relationship between the two needle jump address information. This is for determining whether the needle jump is due to dirt or the vibration, because the needle jump is also caused by vibration.
In the case of stains, the feature that needle jumps occur in adjacent tracks is used.

First, the dirt determination circuit reads out the address information of the position where the previous off-track signal was read out from the predetermined needle jump address storage section and the address information of the position where the off-track signal was output this time from the servo control circuit. And get. Next, if the difference between the address of the previous needle jumped position and the address of the current needle jumped position corresponds to the length of one or several rotations of the track, it is determined that the surface of the mini disk is dirty.

This is because, in the case of a needle jump due to vibration, it is rare that the needle jump occurs at a close position on the surface of the mini disk, while in the case of dirt, the track spacing of the mini disk is considered. In the case of strong dirt, the fact that the needle jumps even at close positions is used.

In the second means, in addition to the matters for specifying the first means, the reading section is provided with a defect detection circuit (DFCT detection circuit) for detecting a decrease in the amplitude level of the signal read by the reading section. , A rotation cycle detection circuit that detects the rotation cycle of the track that the optical pickup is following is also provided, and the dirt determination unit further includes a defect signal (DFCT signal) from the defect detection circuit.
Is output multiple times at a cycle similar to the rotation cycle detected by the rotation cycle detection circuit, and then a stapling occurs at the output timing of the DFCT signal (when an off-track signal is output), the mini disk. It has a function to determine that the surface is dirty.

According to the second means specified by these matters, even if the needle skip is not reached, the decrease in the amplitude level of the RF signal is considered in consideration of the possibility that the decrease in the amplitude level of the RF signal is caused by dirt, and the decrease in the amplitude level of the RF signal is shown. If the DFCT signal is output multiple times in a cycle that is similar to the rotation cycle of the mini disk, it is suspected that it is dirty, and if the needle jumps even once in such a state, it is determined that the surface of the mini disk is dirty. is there. Therefore, the first means determines the stain by the needle jump of 2 times or more, while the second means determines the stain by the needle jump of 1 degree whether or not the needle jump is caused by the stain.

The third and fourth means are a mini disk reproducing device using the dirt detecting device by the first or second means.

The third means is a reading section having an optical pickup for reading the data recorded on the mini disk by following the track of the mini disk, an RF amplifier for amplifying the signal from the reading section, and this RF. A reproduction system for decoding and reproducing the RF signal from the amplifier, a control means for controlling the operation of the reading section according to an external command, and a display for externally displaying the internal state of the music number of the data reproduced by the reproduction system. Equipped with vessels. The control means (system controller) performs control such that, for example, the order of songs to be reproduced is received as an external command by a remote controller or an operation button, and the start address of the song to be reproduced is output to the reading unit. Further, the display device displays the number of the music piece being reproduced, the remaining time of the music piece, and the like. In the third means, when the dirt detection circuit detects dirt on the surface of the mini disk, the fact is displayed. Is displayed externally. For example,
Turn on the "clean lamp" that prompts you to clean the disc.
This indicator is controlled by the control means.

Further, the control means detects a decrease in the amplitude level of the RF signal output by the RF amplifier (DFCT detection circuit), and the optical pickup of the reading section is out of the track being read and the needle jumps. Off-track signal (OFTRK signal)
A servo control circuit that outputs a signal, a rotation cycle detection circuit that detects the rotation cycle of a track that the optical pickup is following, a needle jump address storage unit that stores the address when the OFTRK signal was output last time, and a predetermined And a stain determination circuit for determining the presence or absence of stains on the surface of the mini disk based on the defect signal (DFCT signal) output at the timing of and the OFTRK signal output at a predetermined address.

Here, the DFCT signal output from the DFCT detection circuit indicates that the amplitude level of the RF signal has decreased, while the OFT output from the servo control circuit.
The RK signal indicates that a needle jump has occurred.

Moreover, the dirt determination circuit includes a defect count period setting section for setting conditions for counting the defect signals, and a defect counter for counting DFCT signals satisfying the conditions set by the period setting section.
An off-track count address setting unit that sets conditions for counting OFTRC signals and an off-track counter that counts OFTRK signals that satisfy the conditions set by the address setting units are provided.

The condition in each setting section is whether or not each signal is represented by the rotation period of the mini disk, and each counter counts the signal represented by the rotation period of the mini disk. The dirt determination unit determines whether or not there is dirt based on the count value of each counter.

Regarding the counting condition of the OFTRK signal,
What is done in the address range instead of the cycle is that the mini disk performs intermittent reading, so with a simple timer OFT
This is because it may not be possible to determine whether the output of the RK signal appears in a cycle equal to the rotation cycle. Therefore, the address range corresponding to the rotation cycle is calculated and used as the counting condition.

First, regarding the DFCT signal, when the first DFCT signal is input, the defect count period setting unit sets a constant value around the position of one turn of the track based on the rotation cycle signal from the rotation cycle detection unit. A period and a plurality of fixed periods before and after a position where a plurality of turns are made are set as an effective period in which the DFCT signal is counted as a second time or a plurality of times. That is, the DFCT signals input at the interval equal to the rotation period from the first DFCT signal input are set to be counted.

Further, a plurality of valid periods are set from the period valid as the second DFCT signal to the valid period as the plurality of DFCT signals. The interval between the effective period and the effective period is equal to the rotation cycle. One of the trucks
The term “front and back” of the circled position (a plurality of circles) is intended to absorb the measurement error of the fluctuation of the disk rotation or the rotation cycle and the error of the output timing of the defect signal or the off-track signal.

Further, the defect counter is DFC.
The number of valid periods in which the T signal is output is counted. Alternatively, among the outputted DFCT signals, the signal outputted within the effective period is counted as one even if it is a plurality of pulses, and the defect signals outputted respectively during the plural effective periods continuous in the rotation cycle. To count.

On the other hand, for the OFTRK signal, the off-track count address setting section obtains the number of sectors for one round of the track on which the optical pickup is located based on the rotation period information, and the stitch skipping address in the stitch skipping address storage section. A certain address range before and after the position of one round or a plurality of rounds is set as an effective address range in which the off-track signal is counted as the first or plural times. Further, the off-track counter counts the number of valid address ranges to which the off-track signal is output. When the off-track signal is output within this effective address range, it means that the needle skip has occurred at a position extremely close to the surface of the mini disk.

In the fourth means, in addition to the matters specifying the third means, the rotation cycle detecting section has a rotation cycle calculation function for calculating the rotation cycle based on the address where the optical pickup is located. Moreover, the off-track count address setting unit has a function of correcting the effective address range for counting the off-track signal based on the error information of the predetermined rotation period generated by the rotation period calculation function, and the defect count period setting unit is provided. It also has a function of correcting the effective period for counting the defect signal based on error information of a predetermined rotation period generated by the rotation period calculation function.

In the fourth means specified by these matters, a special circuit is not provided as the rotation period detecting section, and the rotation from the current address where the optical pickup is located to the track including this current address is performed. The cycle is calculated. In this case, since some error occurs, the count condition in each setting unit is corrected by this error.

The present invention is intended to achieve the above-mentioned object by the first to fourth means.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a dirt detecting device for a mini disk according to the present invention. The mini disk dirt detection device includes a reading section 10 for reading data recorded on a mini disk, an RF amplifier 52 for amplifying a signal from the reading section and outputting an RF signal, and the R
A reproduction system for decoding and further reproducing the F signal and a control means for controlling each part are provided.

The control means controls the operation of the reading section 10 and an off-track signal (hereinafter referred to as OF
A servo control circuit 53 for outputting a TRC signal),
A defect detection circuit 12 (hereinafter referred to as a DFCT detection circuit) that captures a decrease in the amplitude level of the RF signal and outputs a defect signal (hereinafter referred to as a DFCT signal);
The needle skipped position based on the rotation cycle detection circuit 14 that detects the rotation cycle T of the mini disk 50 driven by the reading unit 10, the OFTRC signal and the DFCT signal, and the rotation cycle T specified by the rotation cycle signal. And a stain determination circuit 20 for determining whether or not the surface of the mini disk is stained.

The dirt determination circuit 20 includes a timer 16 which starts time counting from the time set by the dirt determination circuit 20.
And a needle jump address storage unit 18 for storing address information of the position where the last needle jump occurred.

Moreover, as shown in FIG. 2, the dirt determination circuit 20 includes a DFCT (defect) count period setting section 21 for setting a count condition of the DFCT signal as a period based on the rotation period signal, and an OFTRK signal count. An OFTRK (off-track) count address setting unit 22 that sets a condition as an address range is provided.

Further, each of the setting units 21 and 22 has a DFCT counter 2 for counting the output of each signal satisfying the conditions set by the setting units 21 and 22.
3 and an OFTRC counter 24 are provided side by side.

Further, each of the counters 23, 24 is provided with a stain determination section 25 for determining the presence or absence of stains based on the output of each counter value.

3 to 7 are explanatory views for explaining the principle of the DFCT signal and the dirt determination based on the DFCT signal. The DFCT detection circuit 12 detects a decrease in the level of the RF signal and outputs it as a DFCT signal. The signal read by the optical pickup 51 is amplified to an appropriate level by the RF amplifier 52 and becomes an RF signal. Disk 5
If there is dirt on 0C, the dirt will confuse the light and
As shown in, the level (amplitude) of the RF signal drops. DF
The CT detection circuit detects the decrease in the level of the RF signal.

However, the decrease in the RF signal occurs not only due to the dirt, but it cannot be determined as dirty only by the DFCT signal. When the dirt A as shown in FIG. 4 is generated, the dirt A on the disk appears every rotation cycle of the disk 50C as shown in FIG. If the rotation cycle T of the disk is known, as shown in FIG.
The FCT signal can be sorted. That is, it can be determined that the DFCT signal a appearing at an interval equal to the rotation period T of the disk is due to dirt, while the DFCT signal b not appearing at an interval equal to the rotation cycle is not due to dirt.

FIG. 7 is an enlarged view of the dirt on the disk.
As described above, even a circular dirt having a diameter of 0.1 [mm] has a width of 62 tracks (track pitch 1.6 μm) (see FIG. 7A). 62 times (6
2 rotations) DFCT signal appears. In addition, if the stain is circular, its effect gradually increases and decreases from the peak (see FIG. 7B). For example, it is conceivable that the DFCT signal is not output on the outer peripheral side of the circular dirt, the DFCT signal is output near the center position of the radius, and the needle skip occurs near the center of the circle.

Therefore, the stain is determined by detecting the DFCT signal continuously for several times or more, and then skipping the DFCT signal for a while during Hi (when the OFTRC signal is output).
It can be judged as dirty.

Further, even if the DFCT signal is not detected several times in a row, if the needle jumps at the same position as the previous time while the DFCT signal is Hi, it can be determined as a stain.

When the DFCT signal is Hi and the needle is skipped at a position where it has been rotated several times from the previous time, it is determined to be dirty.

As described above, it is possible to satisfactorily determine the contamination by the combination of the number of DFCT signals represented by the rotation period and the number of OFTRK signals. Also, the DF that appears in these rotation cycles depends on the selection of the state that promotes cleaning.
The number of CT signals and the number of OFTRK signals may be determined.

Further, depending on the purpose of dirt detection, OF
The stain can be determined only by the TRK signal. In this case, matters related to the DFCT signal are unnecessary.

[Second Embodiment] Next, a mini disk reproducing apparatus having the above-mentioned mini disk detecting apparatus will be described. FIG. 8 is a perspective view showing the external appearance of a mini disk reproducing device incorporating the above-mentioned mini disk dirt detecting device. In the example shown in FIG. 8, a clean display section 30 is added as a display. When the dirt detection device determines that there is dirt, the clean display unit 30 that prompts cleaning of the disk is turned on.

The dirt is detected based on the rotation cycle of the disk 50C. However, CLV control (constant linear velocity control) is performed in the mini disk reproducing device 50, the rotation cycle is different between the inner circumference side and the outer circumference side of the disk 50C, and the recording capacity per track is also different.

FIG. 9 and FIG. 10 are explanatory views for explaining the rotation cycle of this disk. The specifications of the mini disk are as shown in FIG. 9 and below.

Disc diameter 64 [mm] Program area diameter 32 to 61 [mm] Track pitch 1.6 [μm] Disc linear velocity 1.2 to 1.4 [m / s]

FIG. 9B is a table showing addresses, absolute times, and reproduction times. The absolute time is the time when the signal is actually read from the disk 50C, and the reproduction time is the time when the compressed data read from the disk is reproduced as music.

Here, the address is C [cluster] S.
Assuming [sector], the absolute time t [s] is given by the following equation (1,
It is represented by 2).

T = S × 1/75 [s] ... Equation (1) t = (C × 36 + S) × 1/75 [s] ... Equation (2)

Further, with respect to the radius R [mm] of the track traced by the optical pickup and the absolute time and address, the following expression (3) is established. Track pitch P = 1.6 [μm] Disk linear velocity v = 1.2 to 1.4 [m / s] Innermost radius R ₀ = 16 [mm] of program area

Π (R ² −R ₀ ² ) = P · v · t ..... Expression (3)

Therefore, the radius R is expressed by the following equation (4).

[0076]

[Equation 1]

Further, regarding the cycle, the absolute time, and the address, the cycle T is expressed by the following equation (5).

[0078]

[Equation 2]

FIG. 10 shows the relationship between this address, radius and period.

As the value of the address becomes larger and the radius R becomes longer, the period T becomes longer. In this embodiment, various correlations between this address and the cycle T are used.

FIG. 11 shows a block diagram of the hardware resources of the mini disk reproducing apparatus according to the present embodiment. A DFCT detection circuit and a rotation cycle detection circuit are added to the conventional items shown in FIG.

In this embodiment, the dirt determination circuit is realized by the system controller 59. Here, DF
Contamination detection is performed based on the CT signal, the OFTRK signal, and the rotation cycle signal.
CLEAN display is performed as shown in FIG.

FIG. 12 is a timing chart showing the count timing of the DFCT signal. When the system controller 59 operates as the DFCT count period setting unit 21, the system controller 59 sets two α periods shown in FIG. 12 as valid periods. Therefore, as shown in FIG. 12A, when the DFCT signal a is input, the DFCT signal is input again within the valid period, so the DFCT signal is counted up. In this case, the DFCT signal a may be dirty. On the other hand, as shown in FIG. 12B, for the DFCT signal b, the DF
Since the CT signal is not input, it is not determined that it is due to dirt.

The processing by the system controller 59 will be described in detail with reference to the flowcharts of FIGS. 13 to 14. This process is started each time a signal is read from the disc 50C. The normal reproduction repeats reading and waiting, but is started each time reading is started, interrupted when starting to wait, and restarted when reading is started again. When the mini disk 50 is taken out, the contents of various variables and the needle jump address storage unit are cleared.

First, the variable D is reset (step S
1). The variable D represents the number of DFCT signals satisfying the condition of the DFCT count period setting unit 21, and the larger the number, the higher the certainty of dirt detection.

Then, the rotation period T [ms] of the disk is obtained from the rotation period detection circuit 14 (step S2). DF
Steps S1 to S2 are repeated until the CT signal becomes Hi.

DFCT output from DFCT circuit 12
When the signal becomes Hi (step S3), the internal timer 16 of the system controller 59 is reset (TI
ME = 0), and the timer is started (step S4).

Next, the process waits until the value of TIME becomes T-α which is a value obtained by subtracting the margin α such as a measurement error from the rotation period T (step S5). Therefore, this T-α
The input of the DFCT signal up to is ignored.

Further, during the rotation cycle T ± α, DF is again
It is confirmed whether the DFCT signal from the CT circuit 12 becomes Hi (steps S6 to S7).

In steps S6 to S7, TIME is T +.
When α is exceeded, that is, when the DFCT signal does not become Hi during the fixed period before and after the rotation cycle, the process is returned to step S1 and restarted. In this case, D in S3
In the adjacent track on the straight line connecting the upper point of the disk 50C where the FCT signal becomes Hi and the center of the disk 50C, the DFC
Since the T signal did not become Hi, the DFCT signal at S3 is not considered dirty.

On the other hand, the system controller 59 uses the DF
When the CT signal becomes Hi, the value of the variable D is incremented (step S8). That is, the value of the DFCT counter 23 is counted up. In addition, internal timer 1
6 is reset and restarted (step S9).

Further, after the value of the variable D is incremented, if the OFTRK signal becomes Hi (needle jump) while this DFCT signal is Hi, the process proceeds to the recovery process shown in FIG. 14 (step S10).

On the other hand, while this DFCT signal is Hi, OF
If the TRK signal has not become Hi (step S11), the process returns to step S5.

In the recovering process shown in FIG. 14, first, the address where the needle is skipped is stored in A (step S12).
Further, the value of D is a predetermined value (here, "4")
Compared with (step S13), if D ≧ 4, that is, if the level decrease of the RF signal has been repeated five times or more in accordance with the rotation cycle T, CLEAN display is performed (step S21). On the other hand, if D is 3 or less, there is a possibility of needle skipping due to dirt, but it cannot be determined.
Whether or not the staple is skipped is determined by the processing of 4 or less.

First, the address A that was skipped last time
_LAST is read from the needle jump address storage unit 18, and this last needle jump address A _LAST is compared with the current needle jump address A stored in step S12 (step S1).
4) If A = A _LAST , it means that the needle has jumped at the same place, so it is judged that the needle has jumped due to dirt, and CLEAN display is performed (step S21).

If A = A _LAST is not satisfied, first, the positional relationship between the position where the previous needle jump and the position where the current needle jump is made are inspected by the address by the processing from step S16.

First, in step S16, W = A-A
_{By LAST} , the difference between the address skipped last time and the address this time is calculated in sector units. Furthermore, T _A = T × 75
/ 1000 [sector], disk rotation cycle T
[Ms] from the disk to calculate the one rotation Once you address what sector (T _A [sector]), the process proceeds.

Since the address is an integer, T _A should also be an integer, but it is a real number here because an error increases in later calculations. An example is given below.

A _LAST = 500 [cluster] 30 [sector] A = 501 [cluster] 3 [sector] T = 9 [sector] T _A = 8.4 [sector]

Then, it is confirmed whether or not W ≧ 4 × T _A +1 (step S16). “4 × T _A ” is an address difference for four rotations, and “+1” is a margin. In step S16, it is confirmed whether or not the last needle jump is four rotations or more before. If the previous interval between the needle jumps is four rotations or more, error accumulation increases and the periodicity cannot be questioned. Therefore, the needle jump is not determined due to dirt, and the process proceeds to step S22. In step S22, the current stitch skipping address is stored in A _LAST , and the process returns to step S1 shown in FIG.

On the other hand, when the last stitch jump is less than four rotations, it is first determined whether the address difference corresponds to one rotation (step S17). Next, it is determined whether it corresponds to two rotations (step S18), three rotations (step S19), or four rotations.

CLEA is used for each rotation.
N display is performed (steps S17 to S20).

Next, two concrete processing examples by the processing steps shown in FIGS. 13 and 14 will be described.

The first specific example is the example shown in FIG.

First, D = 0 is set (S1). Next, when the rotation cycle T is measured, here, T = 112 [ms]
(S2). Further, T is measured until the DFCT signal becomes Hi (S3).

When the DFCT signal becomes Hi, the timer 16
Is started (S4).

Next, the process waits until the output value of the timer 16 becomes T-α (S5). During this period, the DFCT signal is Hi
Does not affect the processing.

When the DFCT signal becomes Hi, the value of D is set to 1
Increase (S8). Further, the timer is restarted (S9).

The OFTRK signal does not become Hi (S
10), Step S10 until the DFCT signal becomes Lo
To S11 are repeated (S11).

Further, when the DFCT signal becomes Lo, D is passed through steps S5, S6, S8, S9, S10 and S11.
= 2. In the example shown in FIG. 15, this is repeated until D = 5. When D = 5, the OFTRK signal becomes Hi in this example, so the recovery process is performed.

First, the address is stored in A. Here, A = 500 [cluster] 30 [sector]. In step S13, since D ≧ 4, CLEAN display is performed in step S21. Further, the value of A is stored in A _LAST , and the process returns to step S1.

The second specific example is the example shown in FIG.

First, D = 0 is set (S1), and the rotation cycle T is measured (S2). Here, T = 112 [ms]. This measurement is repeated until the DFCT signal becomes Hi.

When the DFCT signal becomes Hi, the timer is started (S4). The timer output value becomes T-α (S
5) During this time, since the DFCT signal becomes Hi again (S6), D = 1 is set (S8), and the timer is restarted.

In this example, since the OFTRK signal becomes Hi, recovery processing is performed (S10). Here, A =
It becomes 500 [clusters] and 30 [sectors] (S12).
Then, not D ≧ 4 (S13), and further, A = A
Not _LAST (S14).

Further, W = 18030 [sectors] and T _A = 8.4 [sectors]. Therefore, W ≧ 4
It becomes × T _A +1 (S16), A _LAST = A = 500 [cluster] 30 [sector], and the process returns to step S1.

Therefore, D = 0 is set (S1), and T = 11.
It becomes 2 [ms]. It waits until the DFCT signal becomes Lo and further becomes Hi (S3).

When the DFCT signal becomes Hi, the timer 16
To start (S4). When the timer output value becomes T-α (S5) and the DFCT signal becomes Hi (S6), D =
It becomes 1 (S8). Then, the timer is restarted (S9).

When the OFTRK signal becomes Hi (S1
0), shift to recovery processing.

A = 501 [cluster] becomes 3 [sector]. Then, not D ≧ 4 (S13), and
_{Since LAST} is 500 [clusters] 3 [sectors], A
= Not A _{LA ST} (S14).

W = 9 [sectors] and T _A = 8.4.
[Sector] (S15).

Since W ≧ 4 × T _A +1 is not satisfied (S16), the process proceeds to step S17.

W-T _A = 9-8.4 = 0.6, and W
Since the absolute value of −T _A is 1 or less (S17), CLEAN display is performed in step S21.

Further, the process returns to step S1 with A _LAST = A.

[Third Embodiment] Next, a third embodiment of the mini disk reproducing apparatus for calculating the rotation cycle of the disk from the address will be described.

A block diagram of the hardware resources is shown in FIG. This is a configuration in which the DFCT detection circuit 12 is added to the conventional configuration, and the rotation cycle detection circuit 14 is removed from the second embodiment. In this second embodiment,
The rotation cycle is obtained without the rotation cycle detection circuit 14.

As described above, since the rotation cycle of the disc changes depending on the position being read, the rotation cycle can be known from the address of the reading position by the above equation (5).

A graph of address vs. rotation period is shown in FIG. If v = 1.3 [m / s], the maximum is +8 [m
s] and -6 [ms] will occur. Here, the error is simplified to ± 8 [m / s].

As described above, the rotation cycle can be obtained from the current address from the equation (5) without using the rotation cycle detection circuit. However, this value includes an error of ± 8 [m / s].

An example of processing of this second mode is shown in FIG. 19 and FIG.
0, the flow chart of FIG.
The changes from the flowchart shown in FIG. 4 will be described.

In step S32, the rotation cycle of the disk is calculated from the current address.

In steps S35 and S37, α is set to β. Since T includes an error of ± 8 [m / s], the margin is increased accordingly. Therefore,
β = α + 8 [ms].

At step S46, 4 × T _A +1 is changed to 4 ×
It is set to T _A +3.4. This is 8 [ms] for T _A
This is because an error of 75/1000 = 0.6 [sector] occurs, and an error of 2.4 [sector] occurs in 4 × T _A.

At step S47, 1 is changed to 1.6 (1+
0.6), and 1 is changed to 2.2 (1 + 2) in step S48.
× 0.6), and 1 is changed to 2.8 (1+
3 × 0.6), 1 is changed to 2.8 (1
+ 3 × 3.4).

Other operations are the same as those in the flow charts shown in FIGS. 13 to 14.

The third embodiment has an effect that the detection circuit is not necessary although the accuracy is slightly lowered due to the error.

As described above, according to the second and third embodiments, if the disc is contaminated with dirt that causes needle skipping during reproduction of the MD, the user is informed of "CLEA".
The “N” display can be turned on to prompt cleaning of the disc.

Moreover, the disc cycle is used to make an accurate determination from both sides of the DFCT signal and the needle jump address.

These are the processes corresponding to the intermittent reproduction which is a feature of MD. That is, since the determination is made by the stapling address other than the continuous detection of the DFCT signal, it is possible to detect the stain well even in the intermittent reading.

[0140]

Since the present invention is constructed and functions as described above, according to the present invention, in the invention according to claim 1, the stain determining circuit causes the address of the position where the previous needle is skipped and the address of the position where the current needle is skipped to be. And the address difference corresponds to the length of one rotation or several rotations of the track, it is determined that the surface of the mini-disc is dirty, so the stapling due to dirt is represented by the rotation cycle. It is possible to satisfactorily separate needle jumps caused by vibrations and needle jumps caused by dirts. Also, since the judgment processing is based on the address range, the periodicity of the needle jumped points is good even during intermittent reading. It is possible to detect the stain on the mini disk by catching the case where the stitch skipped on the track adjacent to the previous stitch skipped track can be detected. It is possible to provide a contamination detection system of mini-disk. Further, in the invention according to claim 3, since the dirt determination circuit determines the presence or absence of dirt based on the output values of the defect counter and the off-track counter, the decrease in the amplitude level of the RF signal occurs at a cycle equal to the rotation cycle. In addition, if a staple skip occurs in this cycle, it can be determined as a stain. Therefore, even if the staple skip does not occur a plurality of times, a temporary stain determination can be performed based on the DFCT signal, and the stain can be detected once more. With this needle jump, it is possible to immediately determine that this needle jump is due to dirt. In particular, in a mini-disk reproducing device for a vehicle, it may be possible to assume that the mini-disk cannot be reproduced due to the vibration while traveling on an extremely bad road. It is possible to determine whether it is due to vibration or the surface of the mini disk is dirty.

[Brief description of drawings]

FIG. 1 is a block diagram showing the structure of a dirt detection device for a mini disk according to the present invention.

FIG. 2 is a block diagram showing a configuration of a dirt detection circuit shown in FIG.

FIG. 3 is an explanatory diagram showing a relationship between the RF signal and the DFCT signal shown in FIG.

FIG. 4 is an explanatory diagram showing an example of a dirty disk.

FIG. 5 is a waveform diagram showing a characteristic of reducing the amplitude level of an RF signal due to dirt.

FIG. 6 is a waveform diagram showing an example of a DFCT signal due to dirt and a DFCT signal that is not determined to be dirty.

7 (A) is an enlarged view of stains on the disk shown in FIG. 4, and FIG. 7 (B) is a graph showing the effect thereof.

8 is a perspective view showing an appearance of a mini disk device having the dirt detection device shown in FIG. 1. FIG.

FIG. 9 is an explanatory view showing the standard of the mini disk, and FIG.
9A is a diagram showing the size of the disc, and FIG. 9B is a chart showing the relationship between the absolute time and the reproduction time.

10 is a graph showing a relationship between an address and a radius and a relationship between an address and a rotation cycle in the standard shown in FIG.

FIG. 11 is a block diagram showing a configuration of a mini disk device according to a second embodiment.

12 is a waveform diagram for explaining the DFCT signal counting condition by the system controller shown in FIG. 12, FIG. 12 (A) is a diagram showing a case where the condition is satisfied, and FIG. 12 (B) shows the condition. It is a figure which shows the case where it is not satisfied.

FIG. 13 is a flowchart showing a previous stage of stain detection processing in the minidisk device shown in FIG.

14 is a flowchart showing a latter stage of the dirt detection process in the minidisk device shown in FIG.

15 is a waveform chart showing a first specific processing example in the flowcharts shown in FIGS. 13 and 14. FIG.

16 is a waveform chart showing a second specific processing example in the flowcharts shown in FIGS. 13 and 14. FIG.

FIG. 17 is a block diagram showing a configuration of a mini disk device according to a third embodiment.

18 is a graph showing a correlation between an address and a rotation cycle used in the configuration shown in FIG.

FIG. 19 is a flowchart showing the previous stage of the dirt detection process in the minidisk device shown in FIG.

20 is a flowchart showing a latter stage of the dirt detection process in the minidisk device shown in FIG.

FIG. 21 is a block diagram showing a configuration of a conventional mini disk device.

22 is an explanatory diagram showing a read operation in the mini disk device shown in FIG. 21. FIG.

FIG. 23 is an explanatory diagram showing an example of intermittent reading by the mini disk device shown in FIG. 21.

FIG. 24 is an explanatory diagram showing an operation example in the case where staple skipping occurs in the mini disk device shown in FIG. 21.

[Explanation of symbols]

10 Readout Unit 12 DFCT Detection Circuit (Defect Detection Circuit) 14 Rotation Cycle Detection Circuit 16 Timer (Internal Timer of System Controller) 18 Needle Jump Address Storage Unit 20 Dirt Judgment Circuit 21 DFCT Count Period Setting Unit (S5 to S7) 22 OFTRK Count Address setting section (S9 to S1
1, S17 to S20) 23 DFCT counter (S8) 24 OFTRK counter (S10) 25 Dirt determination unit 52 RF amplifier 53 Servo control circuit 59 System controller (control means)

Claims (4)

[Claims] 1. A reading section having an optical pickup for reading data recorded on the mini disk by following the track of the mini disk, and a track for controlling the operation of the reading section and being followed by the optical pickup. The servo control circuit that outputs an off-track signal when the needle jumps out of place, the address information of the position where the previous off-track signal was read from the specified needle jump address memory, and the servo control circuit turns off this time. A stain determination circuit for determining whether or not the needle jump is due to stains on the surface of the mini disk based on the address information of the position where the track signal is output, and the needle for this time after the determination by the stain determination circuit is completed. A staple jump address storage unit for storing skip address information, If the address difference between the address of the skipped position and the address of the needle skipped position this time corresponds to the length of one rotation or several rotations of the track, a stain determination unit that determines that the surface of the minidisk is dirty is provided. A mini disk dirt detection device characterized by being equipped. 2. A defect detection circuit for detecting a decrease in the amplitude level of a signal read by the read unit, and a rotation cycle detection for detecting a rotation cycle of a track being followed by the optical pickup. With a circuit, the dirt determination unit outputs the defect signal from the defect detection circuit a plurality of times at a cycle similar to the rotation cycle detected by the rotation cycle detection circuit, and then at the output timing of the defect signal. 2. The mini disk dirt detection device according to claim 1, further comprising a function of determining that the surface of the mini disk is dirty when the stapling occurs. 3. A reading section having an optical pickup for reading the data recorded on the mini disk by following a track of the mini disk, an RF amplifier for amplifying a signal from the reading section, and an RF from the RF amplifier. A reproducing system that decodes and reproduces a signal, a control unit that controls the operation of the reading unit according to an external command, and a display that externally displays an internal state such as a song number of data reproduced by the reproducing system. In a mini-disc reproducing apparatus including: a defect detecting circuit, wherein the control unit detects a decrease in amplitude level of an RF signal output from the RF amplifier;
A servo control circuit that outputs an off-track signal when the optical pickup of the reading unit deviates from the track being read and causes a needle jump, and a rotation cycle that detects the rotation cycle of the track that the optical pickup follows. Based on the detection circuit, the stitch skipping address storage unit that stores the address when the off-track signal was output last time, the defect signal that is output at a predetermined timing, and the off-track signal that is output at the predetermined address, A dirt determination circuit for determining the presence or absence of dirt on the disk surface is provided. The dirt determination circuit detects the track based on the rotation cycle signal from the rotation cycle detection unit when the first defect signal is input. Defects for a certain period before and after one lap and for multiple constant periods before and after several laps Signal count as a second or a plurality of valid periods, a defect count period setting unit, a defect counter that counts the number of valid periods in which the defect signal is output, and the optical signal based on the rotation cycle information. The number of sectors for one round of the track on which the pickup is located is determined, and a fixed address range before and after the position for one or more rounds from the needle jump address in the needle jump address storage section is used for the first or plural off-track signals. An off-track count address setting unit that sets an effective address range to be counted as a second time, an off-track counter that counts the number of the effective address range in which the off-track signal is output, and an output value of the defect counter and the off-track counter Determines the presence or absence of dirt based on That dirt determination unit and the mini-disc reproduction apparatus comprising the. 4. The rotation cycle detection unit has a rotation cycle calculation function for calculating a rotation cycle based on an address where the optical pickup is located, and the off-track count address setting unit is generated by the rotation cycle calculation function. The defect count period setting unit has a function of correcting an effective address range for counting the off-track signal based on error information of a predetermined rotation cycle, and the defect count period setting unit has a predetermined rotation cycle generated by the rotation cycle calculation function. 4. The mini disk reproducing apparatus according to claim 3, further comprising a function of correcting an effective period for counting the defect signal based on the error information of.