JPH08180522A - Magnetic recording/reproducing apparatus - Google Patents

Abstract

PURPOSE: To sample ATF errors of a digital VTR accurately in an ITI area. CONSTITUTION: An envelope signal obtained from a head 1 when a tape recording a digital signal is reproduced is amplified by an amplifier 2, synchronized at a PLL 3, demodulated to the digital signal and input to an ITI synchronous detection circuit 5. When the ITI synchronous detection circuit 5 recognizes that the input data are ones in an ITI area, a pulse generation circuit 6 generates a pulse. On the other hand, the envelope signal obtained from the head 1 when the tape recording the digital signal is reproduced is amplified at the amplifier 2 and input to an ATF circuit 4. An ATF signal is output from the ATF circuit 4 and input to an input terminal of a microcomputer 7. When the microcomputer 7 receives the pulse, the microcomputer 7 immediately samples the ATF signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a digital VCR (Video Cassette Recorder) digital VTR (Video Tape Recorder) for conforming to consumer / user standards.

[0002]

2. Description of the Related Art Before explaining the prior art, 8 mmV
The ATF (Automatic Track Finding) method of TR will be described. In this method, one of four types of pilot signals is superposed on a video signal at the time of recording and is regularly recorded on a tape. When the tape recorded in this way is reproduced, four types of pilot signals are generated by switching for each track reproduction, and these are used as reference signals for the track being reproduced. By detecting the crosstalk component between this reference signal and the pilot signals of the two tracks adjacent to the traced track, and controlling the capstan motor so that the level difference between the detected crosstalk components is eliminated, Align the recording track with the relative position of the head.

Further, in the ATF system, a pilot signal is recorded together with a video signal (or audio).
The tape for head movement is controlled in the following manner. That is, the interference from the track adjacent to the left side has the same strength as the interference from the track adjacent to the right side. Good tracking can be achieved by using such a method.

Since the frequency of the pilot signal differs depending on the track, the interference from the track adjacent to the right side can be identified from the interference from the track adjacent to the left side. With four different frequency sequences, it is possible to identify four consecutive tracks. This proves that the tracking is sufficiently reliable until the tracking error is detected.

The detection of tracking errors is based on the fact that two signals are mixed such that different frequencies are obtained. That is, the frequency of the pilot signal of the scanned track is compared with the interference signal having different frequencies of 16 KHz and 46 KHz. By mixing the signal read from the tape and the signal having the same frequency as the pilot signal of the scanner track, the signal combined at 16 KHz and 46 KHz can be obtained. The signal is then proportional to the interference from the tracks to the left and right of the track. The difference in the amplitude of these two componets is
It becomes the standard of tracking error. The capstan servo loop controls the tape with respect to the movement of the head in such a manner so that the amplitude difference becomes zero.

FIG. 7 shows a control circuit of a conventional capstan motor, in which 41 is a tape and 42 is an A in FIG. 8 which will be described later.
A TF signal sampling circuit, 43 is a circuit of FIG. 9 described later, 44 is an A / D converter, 45 is an error calculation circuit,
46 and 47 are gain circuits, 48 is an error calculation circuit, and 49.
Is a clock counter, 50 is a PWM (Pulse Width Modulati
on: pulse width modulation) generation circuit, 51 LPF (Low Pass)
Filter), 52 is a current amplifier, 53 is a motor driver, 54 is a capstan motor, and 55 is an encoder.

First, the speed control is as follows. PW
An error signal for controlling the capstan motor 54 is output from the M generation circuit 50 by PWM, and this signal is LP
The DC component is extracted at F51 and input to the current amplifier 52. A current corresponding to the error signal is sent from the current amplifier 52 to the motor driver 53, and the motor driver 5
3 causes a current to flow so that the capstan motor 54 rotates. When the capstan motor 54 rotates, a pulse is generated from the encoder 55, and the rotation speed of the motor can be known by counting the interval of this pulse with the clock counter 49. The speed error is calculated from the rotation speed of the motor by the speed error calculation circuit 48, the speed error is multiplied by the gain by the gain circuit 47, and the calculated value is input to the PWM generation circuit 50. In this way, the PWM generation circuit 50 outputs an error signal. In this way, the closed loop is configured to keep the speed of the capstan motor 54 constant.

The method of rotating the capstan motor 54 is the same for the phase control. The capstan motor 5
When the tape 4 is rotated, the tape 41 is moved, and the tape 4
1 and the envelope signal obtained from the head is
It is amplified by the head amplifier and input to the ATF circuit. An ATF signal is output from this ATF circuit, and this ATF signal is input to the A / D converter 44. Also, ATF
The drum phase pulse output from the signal sampling circuit 42 is input to the internal circuit 43 of the microcomputer and sends a sampling command to the A / D converter 44. The A / D converter 44 samples the ATF signal according to the sampling command, and the ATF signal is the phase information of the track, that is, the phase of the capstan motor 54. Then, the phase error is calculated by the phase error calculation circuit 45, the gain is multiplied by the gain circuit 46, and this calculated value is added to the value obtained by multiplying the speed error by the gain. In this way, a closed loop is formed to keep the phase of the capstan motor 54 constant.

FIG. 8 is a circuit configuration diagram for sampling an ATF signal in the 8 mm VTR ATF system.
61 is a head, 62 is an amplifier, 63 is an ATF circuit, 64
Is a microcomputer, and 65 is a drum phase reference generator.

The envelope signal obtained from the head 61 by reproducing the tape on which a predetermined signal is recorded is the amplifier 6
It is amplified by 2 and input to the ATF circuit 63. This AT
An ATF signal is output from the F circuit 63, and this ATF signal is input to the input terminal of the microcomputer 64. Further, since the phase reference of the drum is input to the microcomputer 64 from the phase reference generator 65, the phase of the drum can be known. A sampling point of the ATF signal is calculated from this phase data and sampling is performed.

FIG. 9 shows an internal circuit of the microcomputer.
1 is a gate circuit, 72 is a RAM (Random Access Memor)
y), 73 is an adder, 74 is a RAM, 75 is a comparator, and 76 is a counter.

The microcomputer 64 calculates the sampling point of the ATF signal, and the internal circuit of the microcomputer 64 is, for example, as shown in FIG. The internal counter 76 of the microcomputer keeps time. When the phase pulse of the drum is input, the gate circuit 71 inputs the time data when the pulse is input from the counter 76 to the RAM 72, and the RAM 72 stores the input time data. The phase pulse of the drum is also input to the adder 73, and after the pulse is input, the time data previously stored in the RAM 72 and the timing data prepared in advance are added by the adder 73.

The data obtained by adding the time data when the pulse is input and the timing data prepared in advance represents a certain time after the drum phase pulse is input. The added data is stored in the RAM 74. The comparator 75 constantly compares the data of the counter 76 and the data of the RAM 74, and if these data match, the A / D
A sampling command is sent to the converter 44. That is,
The sampling timing of ATF is synchronized with the phase of the drum, not with the trace position of the tape.

The ATF signal is shown in FIG.
Sampling is performed at the timing of (d). Figure 10
10A is a tape pattern, FIG. 10B is a sampleable range, FIG. 10C is a drum phase reference, and FIG.
(D) is a sampling point.

As shown in FIG. 10A, the track pattern of the tape on which the signal is recorded is originally discontinuous as shown in FIG. 11, but it is considered as continuous for convenience. At this time, the trace direction of the track is the time axis direction of FIG. The envelope signal obtained by reproducing this tape from the head 61 is amplified by the amplifier 62,
It is input to the ATF circuit 63. An ATF signal is output from this ATF circuit 63, and this ATF signal is sent to the microcomputer 64.
Input to the input terminal of. At this time, AT of 8mm VTR
Since the F signal is recorded while being superimposed on the entire area of the recorded track, the sampling range within one track is as shown in FIG. Further, since the phase reference of the drum shown in FIG. 10C is input from the phase reference generator 65 to the microcomputer 64, the phase of the drum can be known. From this phase reference,
The sampling points of the ATF signal shown in (d) are calculated and sampled.

In this sampling method, the sampling point is set only from the phase of the drum regardless of the tape, and therefore the absolute position of the tape cannot be sampled. However, as can be seen from Fig. 10, the 8mm VTR
Since the ATF signal of 1 is superimposed on the entire area of the track, there is no problem even if the sampling point of the ATF signal is set by the phase reference of the drum.

[0017]

Before pointing out the drawbacks of the prior art, the ATF method of the digital VTR of the digital VCR for conforming to the consumer / user standard will be described. In this ATF method, a signal modulated so as to have two kinds of pilot signals at the time of recording is regularly recorded.
When reproducing the tape thus recorded, the pilot signals of two tracks adjacent to the track being traced are detected, and the capstan motor is controlled so that the level difference between the detected pilot signals is eliminated. Align the recording track with the relative position of the head.

In the case of the ATF method of this digital VTR, the ITI (Insert and Track Information) area is A
The level of the TF signal is high, but ATF is used in other areas.
Since the signal level is very small, it is necessary to sample the ATF signal in the ITI area. However, since the time required for the head to trace the ITI area is only about 46 μsec, when sampling the ITI area, it is necessary to set a sampling method with high accuracy. In the conventional method of setting the ATF sampling point based on the drum phase reference, the sampling point is set independently of the tape, so that the absolute position of the tape cannot be sampled. Therefore, if uneven rotation of the drum or disturbance is applied, the ATF can be accurately adjusted from the position in the ITI area.
It becomes impossible to sample the signal.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetic recording / reproducing apparatus capable of accurately sampling an ATF error of a digital VTR in an ITI area.

[0020]

In order to solve the above problems, the present invention provides (1) a reproducing means for reproducing a tape having a predetermined signal recorded thereon, and an ITI area based on the contents reproduced by the reproducing means. And a pulse generating means for generating a timing pulse for ATF sampling based on the determination result by the determining means, and an ATF means for tracking the tape. 2) In the above (1), the determining means is I
A TI synchronization detection circuit, the ITI synchronization detection circuit comprising: a converter for converting serial data into parallel data; and a comparator for comparing the data converted by the converter with the data determined by the standard. It is characterized in that it has a coincidence circuit counter which counts based on the comparison data by the comparator, and when the coincidence circuit counter is advanced from a certain number, a pulse is generated in the pulse generating means.

[0021]

The magnetic recording / reproducing apparatus of the present invention having the above construction (1) discriminates the ITI area from the content reproduced from the tape, and generates a pulse when the reproduced content is discriminated as the ITI area. . Since this pulse is information obtained from the tape, it indicates the absolute position of the ITI area regardless of the phase of the drum. Therefore, the ATF signal can be accurately sampled from the position of the ITI area. (2) Further, the discriminating means for discriminating the ITI area converts the serial data into parallel data,
The converted data is compared with the data determined by the standard, counting is performed based on the comparison data, and a pulse is generated if the count value advances beyond a certain number, so that the position of the ITI area is accurately determined. From the ATF signal can be sampled.

[0022]

Embodiments will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining an embodiment of a magnetic recording / reproducing apparatus according to the present invention, which is a sampling circuit for an ATF signal. In the figure, 1 is a head, 2 is an amplifier, 3 is P
LL (Phase Locked Loop) circuit, 4
Is ATF (Automatic Track Finding) circuit, 5 is IT
I (Insert and Track Information) sync detection circuit, 6
Is a pulse generation circuit.

When the tape on which the digital signal is recorded is reproduced, the envelope signal obtained from the head 1 is transferred to the amplifier 2
The signal is amplified by, is synchronized by the PLL circuit 3, and is demodulated into a digital signal. Then, it is input to the ITI synchronization detection circuit 5. When the ITI synchronization detection circuit 5 recognizes that the input data is in the ITI area, the pulse generation circuit 6 generates a pulse. On the other hand, the envelope signal obtained from the head 1 by reproducing the tape on which the digital signal is recorded is amplified by the amplifier 2 and input to the ATF circuit 4. An ATF signal is output from the ATF circuit 4. The ATF signal is input to the input terminal of the microcomputer 7 shown in FIG. Here, when the pulse is input to the microcomputer 7, the microcomputer 7 immediately samples the ATF signal.

FIG. 2 is a control circuit of the capstan motor according to the present invention. In the figure, 12 is a tape, 13 is an ATF signal sampling circuit shown in FIG. 1, 14 is an A / D converter, and 15 is an error calculation circuit. 16 and 17 are gain circuits, 18 is an error calculation circuit, 19 is a time counter, and 20
Is a PWM (Pulse Width Modulation) generation circuit, 21 is an LPF (Low Pass Filter), 22 is a current amplifier, 23 is a motor driver, 24 is a capstan motor, and 25 is an encoder.

First, speed control is as follows. PW
An error signal for controlling the capstan motor 24 is output by PWM from the M generation circuit 20, and this signal is LP
The DC component is extracted at F21 and input to the current amplifier 22. A current corresponding to the error signal is sent from the current amplifier 22 to the motor driver 23, and the motor driver 2
3 supplies electric current so that the capstan motor 24 may rotate. When the capstan motor 24 rotates, a pulse is generated from the encoder 25, and the rotation speed of the motor can be known by counting the interval of this pulse with the clock counter 19. The speed error is calculated from the rotation speed of the motor by the speed error calculation circuit 18, the speed error is multiplied by the gain by the gain circuit 17, and the calculated value is input to the PWM generation circuit 20. In this way, the PWM generation circuit 20 outputs an error signal. In this way, a closed loop is formed to keep the speed of the capstan motor 24 constant.

The method of rotating the capstan motor 24 is the same for the phase control. Capstan motor 24
The tape 12 moves by rotating the
And the envelope signal obtained from head 1 is
It is amplified by the head amplifier 2 and input to the ATF circuit 4. An ATF signal is output from this ATF circuit 4, and this ATF signal is input to the A / D converter 14. A /
The D converter 14 samples the ATF signal according to the sampling command, and the ATF signal is the phase information of the track, that is, the phase of the capstan motor 24. Then, the phase error is calculated by the phase error calculation circuit 18
And the gain circuit 17 multiplies the gain, and this calculated value is added to the speed error multiplied by the gain. In this way, the closed loop is configured to keep the phase of the capstan motor 25 constant.

FIGS. 3A to 3C are views for explaining the ITI area. FIG. 3A shows the structure of the ITI area.
3B shows the configuration of SSA, and FIG. 3C shows the configuration of TIA. In FIG. 3A, the ITI area is I
TI preamble (pre-amble) and SSA (Start-Sync
blook area), TIA (Tracck Information Area) and ITI post-amble.

The ITI synchronization detection circuit 5 detects, for example, the preamble in this. The data of the preamble is determined by the standard and is composed of 10 bits. This 10-bit unit data appears in a certain cycle, and by recognizing this, the ITI area is determined. This is called ITI synchronization.

FIG. 4 is a block diagram of the ITI synchronization detection circuit in FIG. 1, in which 31 is a 10-bit serial-parallel converter, 32 is a comparator, 33 is comparison data, and 34 is a comparison data.
Is a coincidence circuit counter, and other parts having the same operations as in FIG.

The ITI synchronization detection circuit 5 is integrated into an IC. The serial data sent from the PLL circuit 3 is 10
It is converted into parallel data by the bit serial-parallel converter 31. This data is compared with the data determined by the standard by the comparator 32. If they match, the matching count counter 34 counts the number of times to update the comparison data. If they do not match, the matching count counter 34 And reset the comparison data. If the coincidence counter 34 advances beyond a certain number, a signal is sent to the pulse generating circuit 6 so as to generate a pulse.

FIGS. 5A to 5E are timing charts for sampling the ATF signal. FIG. 5A is a tape pattern, and FIG. 5B is a sampleable range (ITI).
Region), FIG. 5C is a drum phase reference, and FIG. 5D is I.
TI pulse, FIG. 5E shows sampling points respectively.

As shown in FIG. 5A, the track pattern of the tape on which the signal is recorded is originally discontinuous as shown in FIG. 6, but it is considered as continuous for convenience. At this time, the trace direction of the track is the time axis direction of FIG. The envelope signal obtained from the head 1 by reproducing this tape is amplified by the head amplifier 2 and
Input to the circuit 4. An ATF signal is output from the ATF circuit 4, and the ATF signal is input to the input terminal of the microcomputer 7. Here, when the ITI pulse as shown in FIG. 5D is input to the microcomputer 7, the microcomputer 7 immediately samples the ATF signal. In this sampling method, since the sampling point is set from the information on the tape, the absolute position of the tape can be sampled.

[0033]

As is apparent from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: Reproducing means for reproducing a tape on which a predetermined signal is recorded, and I from the reproduced content.
Determination means for determining TI, pulse generation means for generating a pulse when the reproduced content is determined to be ITI,
The ATF means for tracking the tape is provided, and the ATF signal can be accurately sampled from the ITI position by sampling the ATF at the timing when the pulse is generated. (2) Effect corresponding to claim 2: The determining means is a converter that converts serial data into parallel data, and a comparator that compares the data converted by the converter with the data determined by the standard. , A matching circuit counter that counts based on the comparison data by the comparator, and if the matching circuit counter is advanced beyond a certain number, a pulse is generated in the pulse generating means, so that the position of the ITI region is accurately The ATF signal can be sampled.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram of a control circuit of the capstan motor in the present invention.

FIG. 3 is a diagram showing a configuration of an ITI area in the present invention.

FIG. 4 is a block diagram of an ITI synchronization detection circuit according to the present invention.

FIG. 5 is a timing chart of ATF signal sampling in the present invention.

FIG. 6 is a diagram showing a digital signal tape format according to the present invention.

FIG. 7 is a block diagram of a control circuit of a conventional capstan motor.

FIG. 8 is a block diagram of a conventional ATF signal sampling circuit.

FIG. 9 is a block diagram of a conventional ATF signal sampling instruction generation circuit.

FIG. 10 is a timing chart of conventional ATF signal sampling.

FIG. 11 is a diagram showing a conventional analog signal tape format.

[Explanation of symbols]

1 ... Head, 2 ... Head amplifier, 3 ... PLL (Phase Lo
cked Loop: Phase locked loop circuit, 4 ... ATF (Autom
atic track finding circuit, 5 ... ITI (Insert and T)
rack Information) Sync detection circuit, 6 ... Pulse generation circuit, 7 ... Microcomputer, 12 ... Tape, 13 ... ATF signal sampling circuit, 14 ... A / D converter, 15 ... Error calculation circuit, 16, 17 ... Gain control circuit,
18 ... Error calculation circuit, 19 ... Clock counter, 20 ... P
WM (Pulse Width Modulation) generation circuit, 21 ... LPF (Low Pass Filter), 22 ... Current amplifier, 23 ... Motor driver, 24 ... Capstan motor, 25 ... Encoder, 31 ... 10-bit serial-parallel conversion Vessel, 32 ... comparator, 33 ... comparison data, 34
... coincidence circuit counter, 41 ... tape, 42 ... ATF signal sampling circuit, 43 ... microcomputer internal circuit, 44
... A / D converter, 45 ... Error calculation circuit, 46, 4
7 ... Gain circuit, 48 ... Error calculation circuit, 49 ... Clock counter, 50 ... PWM (Pulse Width Modulation) generation circuit, 51 ... LPF (Low Pass Filte)
r), 52 ... Current amplifier, 53 ... Motor driver, 54
... capstan motor, 55 ... encoder, 61 ... head, 62 ... amplifier, 63 ... ATF circuit, 64 ... microcomputer, 65 ... drum phase reference generator, 71 ... gate circuit,
72 ... RAM (Random Access Memory), 73 ... Adder, 74 ... RAM, 75 ... Comparator, 76 ... Counter.

Claims (2)

[Claims] 1. A reproducing unit for reproducing a tape on which a predetermined signal is recorded, and I from the contents reproduced by the reproducing unit.
It is characterized by further comprising: discriminating means for discriminating the TI area, pulse generating means for generating a timing pulse for ATF sampling based on the discrimination result by the discriminating means, and ATF means for tracking the tape. Magnetic recording / reproducing device. 2. The determination means is an ITI synchronization detection circuit, and the ITI synchronization detection circuit is determined by a converter that converts serial data into parallel data, and the data converted by the converter and a standard. And a matching circuit counter that counts based on the comparison data by the comparator. If the matching circuit counter is advanced beyond a certain number, a pulse is generated in the pulse generating means. The magnetic recording / reproducing apparatus according to claim 1, which is characterized in that.