JP2615500B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus (hereinafter, referred to as VTR) for recording / reproducing a video signal as a discontinuous track trajectory inclined in the longitudinal direction of a magnetic tape, The present invention relates to a magnetic recording / reproducing apparatus having a small-diameter cylinder whose cylinder diameter is reduced to 2/3 of that of a conventional one.

2. Description of the Related Art In recent years, magnetic recording / reproducing apparatuses use a small-diameter cylinder.
Many VHS or VHS-C camera-integrated cameras are on the market. In the servo system, there is a state theoretically called back tracking reproduction, and there is a problem that the jitter level becomes nonnegligible even in self-recording reproduction. Here, since the basic operation of the servo system is generally known, a description thereof will be omitted, but an outline of the above-described back tracking reproduction and back tracking correction operation will be described with reference to the drawings.

FIG. 2 is a head configuration diagram of a small-diameter cylinder, in which the A head and the A 'head and the B head and the B' head have the same azimuth angle.

A and b of FIG. 3 are VHS using the small diameter cylinder of FIG.
(Including VHS-C ... the same applies hereinafter.) This shows the recording trajectory (only the relevant portions are shown), where (a) shows a case where the control duty is constant, and (b) shows a case where the control duty changes. Is shown. The rising edges a ₁ and a ₂ of the control track are reproduction control signals (hereinafter, referred to as PBCTL) used for reproduction servo. In the figure, the distance relationship between the control head and the cylinder is ignored. The servo system of VHS system, for a _1, a ₂ of the PB CTL is phase controlled as equal without distinction, be regenerated the track recorded by the A head A or A 'head servo normally controlled Is done. Therefore, despite the self-recording / reproducing, a state where the recording trajectory and the reproducing head trajectory are different theoretically occurs with a probability of 1/2. This state is called back tracking reproduction. A state in which the recording track and the reproducing head track are on the same track is referred to as front tracking reproduction.

In order to improve the jitter caused by the back tracking reproduction described above, one frame by the A and B heads during recording,
There is a method in which the A 'and B' heads can be distinguished from one frame so that it is possible to determine whether or not back-tracking reproduction is performed during reproduction. As shown in FIG. 3B, by making the duty of the control signal (CTL) longer for one frame of the A and B heads than the conventional (60:40),
Make a distinction. In this case, the PB CTL required for the servo system
Has no effect. That is, in FIG. 3a, ▲ ▼: ▲ ▼ = ▲ ▼: ▲
▼ = 60: 40, and there is no distinction between one frame of A and B and one frame of A ′ and B ′. However, in FIG. 3B, for example, ▼: ▲ = 65: 35 ▼: ▲ = 60: 40, and A and B can be distinguished from A 'and B'.

Hereinafter, the back tracking correction operation based on the above method will be described with reference to the drawings.

FIG. 4 shows a block diagram of a back tracking correction circuit of the magnetic recording and reproducing apparatus. 1 is the duty of the recording control signal (hereinafter referred to as REC CTL) from 60:40 to 65:
Recording control signal duty converter (hereinafter referred to as duty converter) for converting into 35 and 60:40 repetition, 2 is back tracking reproduction discriminator (hereinafter called back tiger discriminator), 3 is acceleration pulse generator Reference numeral 4 denotes a capstan phase inversion detector (hereinafter referred to as an inversion detector). A recording control signal (hereinafter referred to as REC CTL (IN)) before duty conversion is input to an input 11 of the duty converter 1, a head switching signal (hereinafter referred to as HSW) is input to an input 12, and an input 13 Is input with a 1/2 head switching signal (hereinafter, referred to as 1/2 HSW) having a cycle twice as long as HSW, and a recording control signal after duty conversion (hereinafter, referred to as REC CTL (OUT)) is output at output 14. It is supplied to a control head (hereinafter referred to as a CTL head). A reproduction control signal (hereinafter referred to as PSCTL) is input to an input 21 of the back tiger discriminator 2, an HSW is input to an input 22, a 1 / 2HSW is input to an input 23, and an input 25
, A back tracking determination operation command is input. Then, an acceleration command signal is output to the output 24, and the acceleration pulse generator 3
Is supplied to an input 31. The output 32 of the acceleration pulse generator 3 is accelerated pulse is output, the input 41 of the inverting detector 4 used as a capstan control signal E _CAP is inputted PB CTL, HSW is input to the input 42, and An acceleration stop signal is output at an output 43 and supplied to an input 33 of the acceleration pulse generator 3.

The operation of the back tracking correction circuit configured as described above will be described below.

(I) During recording, as shown in FIG. 5, RSW (a) and 1/2
The phase relationship of HSW (b) is defined, and REC CTL (OUT) is applied to these two signals via the duty converter 1.
(C) is obtained. That is, HSW (a) is at the high level (H)
Therefore, for one frame in which 1 / 2HSW (b) starts at the high level (H), the duty of REC CTL (OUT) is ▲
▼: ▲ ▼ = 65: 35, RSW (a) starts at (H), 1 / 2HSW (b) starts at LOW level (L) 1
For the frame, the duty of REC CTL (OUT) (c) is ▼ :： = 60:40. The aforementioned REC CTL (OUT) is supplied to the CTL head and recorded.

(Ii) During reproduction, as shown in FIG. 6, the rise of PBCTL (d) is controlled by the operation of the servo system so that it rises to the center of the slope of the servo error reference signal (e). This means that the servo system delays the phase when the rising edge of PBCTL (d) is in the "+" part of the servo error signal reference (e) and in the "-" part. This is because it acts in the direction. Also HSW
(A) and 1 / 2HSW (b) have the same phase relationship as in FIG. 5, and these signals are input to the back tiger discriminator 2, and the phase reference signal (c) is created by the back tiger discriminator 2. Is done. That is, the relationship shown in Table 1 below is obtained.

Here, L... LOW level, H... High level When PB CTL (d) is in the state shown in FIG. 6, the phase of one frame is shifted from REC CTL (OUT) (c) in FIG. It is in a state of so-called back tracking base.

The one frame of the rising edge a ₁ phase duty 65:35 PB CTL (d) with respect to the phase reference signal (c) is in any of the periods L or H, at the time of reproduction tracking back Or a table can be determined. The rising edge a ₁ of H, the relationship of the reproduction tracking state and L period is a relationship of the following Table 2.

As described above, as a result of determining whether the reproduction tracking state is back or front, in the case of back tiger reproduction, an acceleration command is output from the back tiger discriminator 2 and input to the acceleration pulse generator 3, and the acceleration pulse (j) is output. Then, the capstan starts accelerating. Further, in the inversion detector 4, an inversion detection gate signal (h) is generated in synchronization with the HSW signal (a), and the PB CTL obtained after acceleration of the capstan by the acceleration pulse.
When the rising edge of the (acceleration) signal (f) coincides with the detection period (High level) of the inversion detection gate (i), the acceleration stop command (i) is output, and the acceleration pulse (j) ends.
Capstan acceleration stops. Thereafter, by the operation of the servo system, the rising of PBCTL (acceleration) (f) after acceleration is controlled to be at the center of the servo error reference signal (e), and the phase inversion operation of the capstan is completed.

The present invention relates to the above-described back tracking reproduction determination method. Next, a conventional back tracking reproduction determination method will be described. FIG. 7 shows a block diagram of a conventional back tiger discriminator. 51 is a reproduction control signal duty measuring device (hereinafter referred to as a CTL duty measuring device), 52 is a first storage device, 53 is a first comparator, 54 is a data storage device, 55 is an HSW signal reader, and 56 is a backside. It is a tracking determination device. PB CT at input 21 of CTL duty measuring instrument 51
When the L signal is input and a back tracking determination operation command is input to the input 25, a value obtained by measuring the CTL duty is output to the output 71 and supplied to the input 72 of the first storage device 52. A value obtained by measuring the CTL duty from the output 73 of the first storage device 52 is input to an input 74 of the first comparator 53,
Data stored in advance from an output 76 of the data storage device 54 is input to an input 75, an HSW signal reading command is output to an output 77, and supplied to an input 78 of the HSW signal reading device 55. The HSW signal reader 55 receives an HSW signal and a 1/2 HSW signal from inputs 22 and 23, respectively.
The input 80 of the back tracking determination device 56 receives the HSW signal read data from the output 79 of the HSW signal reader 55, and the input 81 receives the CTL duty measurement value from the output 82 of the first storage device 52. The acceleration command is supplied from the output 24 to the above-mentioned acceleration pulse generator.

The operation of the conventional example configured as described above will be described below. When a back tracking discrimination operation command is issued due to mode transition, etc., the CTL duty measurement
The duty of the CTL signal is measured, and “1” is stored in the first storage device 52 when the duty is 63:35, and “0” when the duty is 60:40.
Is output. The first storage device is an 8-bit storage device and CT
The output signals from the L duty measuring device 51 are sequentially stored. The data storage device has two types of 8-bit data stored in advance. After the CTL duty measurement is performed eight times, the data from the first storage device 52 is stored in the data storage device.
When the data coincides with the data 1 or 2 in 54, an HSW reading command is output from the first comparator 53 to the HSW reading device 55.
The HSW reader 55 receives the HSW signals from the inputs 22 and 23 and 1 / 2HSW
The signal level is read and the phase reference signal shown in Table 1 is generated and supplied to the back tracking determination device 56. The back tracking determining device 56 determines whether the back tracking state is the front tracking state or the back tracking state based on the relationship of the second table based on the phase reference signal and the CTL duty measurement data from the first storage device. In the case of the state, an acceleration command is supplied from the output 24 to the acceleration pulse generator 3 shown in FIG. With the above configuration, it is possible to determine whether the front tracking state or the back tracking state is the back tracking state.

However, in the above configuration, the duty measurement of the reproduction control signal is completed and the first comparator
53, when the HSW signal reading command is output, the servo pull-in process is performed, and as shown in FIG. 8, the rising of the reproduction control signal is located near the rising or falling of the phase reference signal. In the case of pulling in in the direction of the arrow of, it is determined that back tracking is in spite of trying to pull in to the front tracking state, an acceleration pulse is generated from the back tracking determination device 56, and the back tracking state is entered. Had issues.

In view of the above problem, the present invention stores the tracking state determined from the phase reference signal from the HSW signal reader 55 and the CTL duty measurement value from the first storage device 52, and further stores the tracking state at the next rising edge of the PB CTL signal. If the same detection is performed and the same tracking state is not determined consecutively, the configuration is changed so that the above determination does not become effective. It is an object of the present invention to provide a magnetic recording / reproducing apparatus which can accurately determine a tracking state.

Means for Solving the Problems To solve the above problems, a magnetic recording / reproducing apparatus according to the present invention comprises a reproduction control signal input to a first input unit and a back tracking discrimination operation instruction input to a second input unit. A CTL duty measuring device for outputting the reproduction control signal duty measurement value from the first output portion based on the first output portion, and a control signal duty measurement value input to the third input portion for storing the second control signal duty measurement value. A first storage device that outputs the stored control signal duty measurement value from an output unit and a third output unit, a data storage device that outputs pre-stored data from a fourth output unit, and a fourth storage device. Based on the control signal duty measurement value input to the input unit and the pre-stored data input to the fifth input unit, the fifth A first comparator that outputs a head switching signal reading command from an output unit, the head switching signal reading command input to a sixth input unit, a head switching signal input to a seventh input unit, and an eighth input 1/2 having a cycle twice as long as the head switching signal inputted to the section
An HSW signal reader for outputting a phase reference signal from a sixth output section based on a head switching signal;
Back tracking for outputting a tracking state value from a seventh output unit based on the phase reference signal input from an input unit and a control signal duty measurement value from the first storage device from a tenth input unit Judging device and eleventh
A second storage device that stores the tracking state value input from the input unit of the second unit and outputs the stored tracking state value from the eighth and ninth outputs; A third storage device that stores a tracking state value from the second storage device and outputs the tracking state value from a tenth output unit, and a tracking from the second storage device that is input from a thirteenth input unit An acceleration command generator for outputting an acceleration command from an eleventh output unit based on a status value and a tracking status value from a third storage device input from a fourteenth input unit.

Operation According to the present invention, the discrimination between the front tracking and the back tracking in the servo pull-in process can be prevented by the above-described configuration, and as a result, the jitter generated by the back tracking can be prevented.

Embodiment Hereinafter, a magnetic recording and reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a back tracking reproduction discriminator in a magnetic recording and reproducing apparatus according to one embodiment of the present invention. The same components as those in the related art are denoted by the same reference numerals, and the details are omitted.

In FIG. 1, reference numeral 51 denotes a CTL duty measuring device, 52 denotes a first storage device, 53 denotes a first comparator, 54 denotes a data storage device, 55 denotes an HSW signal reader, and 56 denotes a back tracking judgment device. Has the same configuration as the conventional one.

57 is a second storage device, 58 is a third storage device, and 59 is an acceleration command generator.

In the magnetic recording / reproducing apparatus configured as described above,
Hereinafter, the operation will be described with reference to FIG.

The back tracking determination device determines the tracking state based on the control signal duty measurement value from the first storage device 52 and the phase reference signal from the HSW signal reader 55, and sets “1” for front tracking. In the case of back tracking, "0" is output to the second storage device 57. The second storage device 57 stores the tracking state value.

Thereafter, even at the next rising edge of the reproduction control signal, the back tracking determination device 56 is based on the control signal duty measurement value from the first storage device and the phase reference signal from the HSW signal reader 55. The tracking state is determined, and the data is stored in the second storage device 57.
Output to When the tracking state value is supplied from the back tracking determination device 56, the second storage device 57 supplies previously stored data to the third storage device 58. The acceleration pulse generator compares the data stored in the second storage device 57 with the data stored in the third storage device 58, and determines whether it is front tracking or back tracking for the first time when the data coincide with each other. Supplies an acceleration command to the acceleration pulse generator 3 shown in FIG. The above operation is performed in the second
This is continuously performed until the data in the storage device 57 of the third storage device matches the data in the third storage device.

As described above, according to the present embodiment, by providing the second storage device 57, the third storage device 58, and the acceleration command generator 59, it is possible to accurately determine the front tracking and the back tracking in the servo retracting process. Will be able to do that.

Effect of the Invention As described above, according to the present invention, it is possible to eliminate the discrimination error between the front tracking and the back tracking in the servo pull-in process, so that the back tracking correction operation can be performed accurately. An excellent effect of preventing jitter during tracking reproduction can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a back tracking reproduction discriminator in a magnetic recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a head configuration diagram of a small-diameter cylinder, and FIG. 3 shows a tape recording pattern of a VHS VTR. FIG. 4 is a block diagram of the back tracking correction circuit, FIG. 5 is a timing chart showing an operation timing at the time of recording, FIG. 6 is a timing chart showing an operation timing at the time of reproduction, and FIG. FIG. 8 is a timing chart showing the timing of a tracking discrimination error in the conventional example. 51 CTL duty measuring device, 52 first storage device, 53 first comparator, 54 data storage device, 55
... HSW signal reader, 56... Reverse tracking determination device, 57... Second storage device, 58.
...... Acceleration command generator.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenji Terai 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-64-25337 (JP, A)

Claims (1)

(57) [Claims] A first output unit for outputting the reproduction control signal based on a reproduction control signal input to a first input unit and a back tracking operation determination command input to a second input unit; A control signal duty measuring device for outputting a duty measurement value, the control signal duty measurement value input to a third input portion being stored, and the stored control being transmitted from a second output portion and a third output portion. A first storage device for outputting a signal duty value, a data storage device for outputting data stored in advance from a fourth output unit, the control signal duty measurement value input to a fourth input unit, and a fifth storage device. A head switching signal reading command is output from the fifth output unit based on the pre-stored data input to the input unit. And a head switching signal read command input to a sixth input unit, a head switching signal input to a seventh input unit, and a head switching signal input to an eighth input unit. A head switching signal reader for outputting a phase reference signal from a sixth output section based on a 1/2 head switching signal having a double period, and a phase reference signal input from a ninth input section. A back tracking determination device for outputting a tracking state value from a seventh output unit based on a signal and a control signal duty measurement value from the first storage device from a tenth input unit; A second storage device that stores the tracking state value input from the unit and outputs the stored tracking state value from eighth and ninth outputs; and a twelfth input. A third storage device that stores a tracking state value from the second storage device input to the second storage device and outputs the tracking state value from a tenth output unit; and a second storage device that inputs the tracking state value from a thirteenth input unit. Command generator that outputs an acceleration command from an eleventh output unit based on a tracking status value from a storage device of the third storage device and a tracking status value from a third storage device input from a fourteenth input unit A magnetic recording and reproducing device comprising: