JPS6238567A - Image playback device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image reproducing apparatus using a disk-shaped recording medium, and particularly to a time axis fluctuation correction method when reproducing a medium on which a still image signal is recorded.

2. Description of the Related Art Problems that the invention aims to solve in the conventional method for correcting time axis fluctuations in reproduced image signalsHowever, in the method of correcting using a fluctuation absorption memory, there are strict demands on the accuracy of circuit components, etc. The proportion of fluctuation correction becomes extremely high.

In addition, in the case of the correction method in which the playback head is vibrated in the time axis direction, since the playback head is vibrated, the contact conditions between the recording medium and the playback head change, the output of the playback head decreases, and the S/N of the reproduced image signal increases. There was a problem in that the value decreased. In the case of the above two types of correction methods, since they are closed loop configurations, correction is performed even if there is almost no time axis variation, which is wasteful.

The present invention focuses on the fact that most of the time axis fluctuations when using a disk-shaped recording medium are caused by eccentricity between the medium and the spindle that engages with it, and has a simple configuration without reducing the playback head output. An object of the present invention is to provide an image reproducing device that can correct temporal axis fluctuations inexpensively and reliably.

Means for Solving the Problem An image reproducing apparatus is provided with a rotation control means for controlling the rotation of a disc-shaped recording medium, an amplitude changing means for changing the amplitude of a correction signal, and a phase changing means for changing the phase of the correction signal.

According to the present invention, the phase and amplitude of the time axis fluctuation are changed by the amplitude change means and the phase change means before applying the correction signal to the rotation control means, and then applied by the control means, and then the amplitude and the amplitude are changed by the above-described configuration. Time axis fluctuations are corrected by alternating and finely adjusting the phase.

Example An embodiment according to the present invention will be described below.

FIG. 1 is a block diagram of an image reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of each block.

In the figure, an image signal recorded on a disk-shaped recording medium (hereinafter referred to as a sheet) 2 rotated by a sheet motor 1 is extracted by a reproduction head 3 and a reproduction amplification circuit 4. The signal is reproduced through the demodulation circuit 6.

Also, the leakage magnetic flux of the magnet 6 rotating together with the seat 2 is PG
A frequency generator (FG) 9 that generates a signal according to the PG pulse 8 detected by the coil 7 and the rotational speed of the seat motor 1
The FG pulse 10 is input to a motor control circuit 11, and its control output 12 is amplified by a motor drive circuit 13 to control the rotation of the seat motor 1.

Further, the PG pulse 8 and the FG pulse 10 are input to a microprocessor 14, and the microprocessor 14 sends a signal 16 synchronized with the rotational speed of the sheet 2 to a filter 16. Moreover, this signal 15 is connected to a flip-flop (hereinafter F
, F) is also sent at the end of the first round. The signal passing through the filter 16 is sent to a voltage control amplifier circuit (hereinafter referred to as VCA) 18
．． The signal is input to the motor drive circuit 13 as a correction signal 20 via an analog switch 19 . As a result, the rotational speed of the seat motor 1 is modulated sinusoidally. At this time, the microprocessor 14 sends a correction δN signal 21 to F, F17.
F and F17 correct the signal 16. A signal like 22 is sent to the analog switch 19 using the ○N signal 21, and a correction signal is output to the motor drive circuit 13.

Here, the reason why the correction ON signal 21 is latched using the signal 15 at F and F17 is that, for example, when the amplitude of the correction signal 20 is small, when it is applied to the motor drive circuit 13, the correction ON signal 21 is latched using the signal 15. , if applied from the zero point position, there is a possibility that the seat motor 1 may lose control or hunting may occur. Therefore, in order to ensure that the voltage is applied from point A, the correction ON signal 21 is latched with the signal 16.

Also, the synchronization signal component 23 of the reproduced image signal from the demodulation circuit 6
is a frequency-voltage conversion circuit (hereinafter referred to as F-V) 24. Filter 25. Rectifier circuit 26. Analog-digital conversion circuit (hereinafter referred to as A-D) 27 and phase detection circuit 28
A jitter information detection circuit 29 consisting of a jitter information detection circuit 29 detects a phase signal 30 indicating the amount of low frequency component of the time axis fluctuation, the amount of the low frequency component, and the phase of the low frequency component and outputs it to the microprocessor 14.

The microprocessor 14 is a jitter information detection circuit 29
An amplitude command signal 32 corresponding to the amount of time axis variation is sent to the D-A 31 which sets the amplitude of the correction signal 20 based on a signal indicating the amount of time axis variation.

Further, a square wave signal 15 serving as a correction signal is sent to the filter 16 using the phase signal 3o, FG pulse 1o, and PG pulse 8.

Here, a schematic flowchart is shown in FIGS. 3 and 4 and will be described below.

First, jitter information (phase and amount) before applying the correction signal 2o to the seat motor 1 is taken into the microprocessor 14. The microprocessor 14 first checks the amount of jitter before correction, and returns to the main program if the amount of jitter is less than 0.01 inch.

In the case of a jitter amount of about 0.01%, this is a value that cannot be visually confirmed on a normal monitor TV due to the influence of AFC, and there is no need to perform correction, so return to the main program. . Also, the accuracy has been increased.

If not, change 0.01% to 0. There is no problem even if it is set to 0.001% even at ω3chi. When the jitter amount is 0.01% or more, the rising or falling edge of the phase signal 30 is detected using the PG pulse 8 and the FG pulse 10 in order to detect the phase of the jitter with respect to the rotation period of the sheet 201. . The flowchart shown in FIG. 3 has been completed up to this point. For example, PG pulse 8 is used at this time.
When obtaining the phase value of the correction signal when recording is performed on multiple tracks under the same recording conditions, select one of the multiple tracks.
If the jitter phase signal of only one track is detected, the other tracks will also have the same phase, resulting in a reduction in time.

In other words, if you count and store the jitter phase value from the rising or falling position of PG pulse 8 by counting the number of FG pulses 1o, even if you move to another track, PG pulse 8 and FG < By checking the pulse 1o, a correction signal can be easily created.

After detecting the phase of this jitter and the amount of jitter, it is calculated in the microprocessor 14 according to the amount of jitter, and the amplitude command signal 32 is sent to the D-A 31, and the square wave signal 15 is filtered according to the phase of the jitter. Send on 16th. At this time, the phase relationship between the square wave signal 160 phase and the jitter phase signal is as follows:
The value is obtained by counting several pulses of 0. 30 and 1 in Figure 2
This is the relationship of 5. This phase shift occurs due to the frequency characteristics of the control of the seat motor 1 and the frequency characteristics of the filters 26 and 16.

In addition, since the square wave 16 is created in one rotation period in this embodiment, the signal is "L" for four periods of % of the number of FG pulses during one rotation, and the signal is "L" for the remaining % of the number of pulses. By configuring the microprocessor 14 to count the number of FG pulses 10 so as to send out "H", a correction signal synchronized with the seat motor 1 can be easily created.

In other words, the phase resolution due to the correction signal 20 is F during one rotation.
Determined by the number of G pulses. If the number of FG pulses per revolution is small, the resolution can be easily improved by using a PLL or the like.

Next, based on the jitter information before correction, a correction signal 2° whose amplitude value and phase are set as described above is applied to the seat motor 1, and after a predetermined period of time, the jitter information is again stored in the microprocessor 14. take in. Then, as in the initial stage, it is again determined whether the jitter amount is 0.01% or less. If it is more than that, change the phase by “+1” from the initial phase value.
Set to . This "+1" is the FG pulse 1 obtained by counting the number of FG pulses 10 from the PG pulse 8 above.
It is to set the number of 0s to be +1n more.1 in Figure 2.
The solid line in 5 is the phase of the initially obtained correction signal, and the broken line D
The side is “+1”.

In this case, it does not matter whether you are doing it from the “+” side or not.
There is no problem with the operation even if the phase is changed depending on the direction.

Then, the jitter information is loaded into the microprocessor 14 again and it is determined whether it is less than Q, 01ch. If it is more than that, compare it with the previous jitter amount, and if it has decreased, is the current phase "+" (advanced)? -" (delay) is determined and the phase is changed by "+1" and "-1", respectively. Also, if the amount of jitter increases, the current phase will change to “+” or “-”
If it is ``-'', it will return to the phase before the increase.''
+1" to jump to the amplitude change program that changes the amplitude. If it is "+", it is determined whether the data at that time is the first data. This is based on the standard detected before correction. (solid line in Figure 2 15) to the position D indicated by the broken line in Figure 2 15. If the answer is "No", the amount of jitter will increase if the phase is moved to the "+" side. increases, so in order to return to the phase value before the increase, set "-1" and jump to the amplitude change program in the same way as above.If "YES", the position of the solid line 15 in Figure 2 is set. Since the change in the amount of jitter on the "-" side has not been confirmed, the phase is set to "-2n" and the change in the amount of jitter is confirmed again in the same manner as above.

By carrying out the above operations, it was possible to detect the phase position of the correction signal 2° at which the amount of jitter at the initially set amplitude value is minimized. Then, the amplitude value is changed. 5 is a flowchart of FIG. 4.

In this case, is almost the same as the phase change program, so to explain briefly, change the initially set amplitude value to "+"
The minimum amount of jitter is found by varying it to ", -".

When the minimum amount of jitter is 0.01% or more, the phase and amplitude are changed to find the amplitude and phase values of the correction signal 20 that are o and o1% or less.

The above is a flowchart of an embodiment of the present invention. In this flowchart, the phase change and the amplitude change are performed one step at a time. In the initial stage, the number of steps is large, and as the amount of jitter decreases, the number of steps is increased. Precision increases by making it smaller.

As described above, the time axis fluctuation caused by eccentricity can be corrected, but this fluctuation consists of the fundamental wave whose period is one rotation period of the sheet 2 and its harmonics, but since the fundamental wave is the main wave, the microprocessor Frequency and filter 2 created in
Characteristic No. 5 corresponds to this fundamental wave. In addition, in the embodiment, the correction signal is created within the microprocessor 14, but it can also be created using hardware, for example, by dividing the frequency of the FG pulse, and changing the phase by changing the timing at which the divided period is reset. can be done.

The reproducing head 3 can operate in the same manner whether it is a magnetic head or an optical head, and whether the magnetic medium is a hard disk or a flexible disk.

Effects of the Invention As described above, in the present invention, the rotational speed of the sheet motor 1 is modulated to correct for time axis fluctuations, so this correction does not change the contact conditions of the reproducing head to the sheet. , the playhead output does not decrease. Therefore, there is no deterioration in the S/N of the reproduced image signal due to the correction.

Furthermore, since the variation absorption memory used conventionally is not used, the increase in circuit cost due to time axis variation correction is negligible.

In addition, the correction signal is created and the phase is changed using the FG pulse and P.
By using the G pulse, it is possible to obtain a correction signal synchronized with the rotation period of the seat motor, and since the phase is changed in synchronization with the FG pulse, a simple configuration is possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an image reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram of each block, and FIGS. 3 and 4 are schematic flowcharts. 1... Seat motor, 2... Seat,
3...Reproduction head, 4...Reproduction amplification circuit, 6...Demodulation circuit, 8...PG pulse, 10...FG pulse , 11...Motor control circuit, 13...Motor drive circuit, 14
...Microprocessor-116...
Filter 1,) 1.8...VCA, 20...
...Correction signal, 24...F'1 -V conversion circuit, 25...Filter, 2θ・mountain・
- Rectifier circuit, 27...A-D, 28...
・Phase detection circuit, 29...Jitter information detection circuit, 3Q...Phase signal, 31...D-
Ao Name of agent Patent attorney Toshio Nakao and 1 other person No. 3
Figure 4

Claims (9)

[Claims] (1) A rotation control means for controlling the rotation of a rotating disc-shaped recording medium based on speed information and phase information of the disc-shaped recording medium, and an amplitude of a low frequency component of a time axis fluctuation of a reproduced image signal of the disc-shaped recording medium. time axis fluctuation amplitude detection means for detecting the value, time axis fluctuation phase detection means for detecting the phase of the low frequency component of the time axis fluctuation, and generating a sinusoidal correction signal related to the rotational speed of the disk-shaped recording medium. a correction signal generating means for changing the amplitude of the correction signal of the correction signal generating means in accordance with a detection signal of the time axis fluctuation amplitude detecting means, a detection signal of the time axis fluctuation detecting means and the disk. a phase changing means for changing the phase of the correction signal of the correction signal generating means using at least one of three types of signals of speed information and phase information of the shaped recording medium; and an application for applying the correction signal to the rotation control means. and a control means for controlling the applying means, the amplitude changing means, and the phase changing means, and configured to suppress temporal fluctuations of the disk-shaped recording medium by the correction signal. A reimage reproduction device. (2) A patent characterized in that the phase change means is configured to use the detection signal of the time axis variation phase detection means, the speed information and phase information of the disc-shaped recording medium, or either the speed information or the phase information. An image reproducing device according to claim 1. (3) The correction signal generating means includes speed information of the disc-shaped recording medium;
The image reproducing apparatus according to claim 1, characterized in that the image reproducing apparatus is configured to use at least one of the phase information. (4) The image reproducing apparatus according to claim 2, wherein the control means is configured to operate the application means after operating the amplitude change means and the phase change means. (5) A patent characterized in that the control means is configured such that the amplitude changing means, the phase changing means, and the applying means do not operate if the detection signal of the time-axis variation amplitude detecting means is less than a predetermined value before the applying means operates. An image reproducing device according to claim 1. (6) The control means is configured to maintain the operation of the amplitude change means and the phase change means when the time axis variation amplitude detection signal is less than a predetermined value after the application means operates. The image reproducing device described in . (7) The image reproducing apparatus according to claim 6, wherein the control means is configured to operate after a predetermined period of time has elapsed after the operation of the amplitude change means and the phase change means are maintained. (8) The control means maintains the operation of either the amplitude change means or the phase change means after the application means operates, and changes the amplitude change means and the phase change after a predetermined period of time or according to the detection signal of the time axis variation amplitude detection means. 2. The image reproducing apparatus according to claim 1, wherein the image reproducing apparatus is configured to switch the operating state of the means. (9) The image reproducing apparatus according to claim 1, wherein the phase changing means is configured to use speed information of the disk-shaped recording medium after the control means applies a correction signal to the rotation control means. .