JP3363572B2 - 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, and more particularly to a magnetic recording / reproducing apparatus in which a first control head reads a control signal recorded on a magnetic tape at a predetermined pitch. The present invention relates to a magnetic recording / reproducing apparatus for controlling a rotation position of a stun motor. In a conventional magnetic recording / reproducing apparatus, a control signal CTL recorded on a magnetic tape is read out by a control head so that the video head can appropriately trace a video track recorded on the magnetic tape.
This controls the rotation of the capstan motor. However, in the conventional magnetic recording / reproducing apparatus, since the control signal CTL is recorded every other field as shown in FIG. 2, when performing slow reproduction in field units, The following problems have occurred. In other words, in a field where the timing is in sync with the control signal, a video with less noise can be reproduced by moving the magnetic tape to a desired position. In order to properly trace the video track, the F
A circuit for counting G and controlling the feed time by the capstan motor is required, and there has been a problem that the circuit configuration becomes complicated. SUMMARY OF THE INVENTION It is, therefore, a main object of the present invention to provide a magnetic recording / reproducing apparatus which has a simple circuit configuration and can suppress generation of noise during slow reproduction on a field basis. [0005] The present invention relates to a magnetic tape.
A video track recorded in helical scan mode
Probe and selectively enable based on head switching pulse
Multiple playback heads, predetermined along the length of the magnetic tape
The first control head that reads the control signal recorded at the pitch
, Which is disposed at a first predetermined distance from the first control head.
Control head for reading the control signal
For selecting one of the head and the second control head
Control head selected by the
Tracking based on the control signal read by the
In response to feed operation instructions that occur periodically
To transport the magnetic tape over a second predetermined distance
The stun motor and the head switching
Switching means in response to the first level change
A magnetic recording / reproducing apparatus including a switch control unit for switching selection . According to the first control head, for example, 20.
The second control head disposed at a position separated by 5p in the running direction of the magnetic tape operates when performing slow reproduction of the magnetic tape in, for example, a field unit. When the first control head reads the control signal when the video head traces a field at the same timing as the control signal CTL, the rotation of the capstan motor is controlled by the read control signal CTL. Subsequently, when the video head traces the next field, that is, a field that does not match the timing of the control signal CTL,
The second control head reads the control signal read by the first control head. Thus, the rotation of the capstan motor is controlled even in a field where the timing does not match the control signal CTL. According to the present invention, since the rotation of the capstan motor is controlled by the second control head reading the control signal CTL, the slow reproduction is performed in a field unit with a simple circuit configuration. Generation of noise at the time can be suppressed. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings. Referring to FIG. 1, a video tape recorder 10 of this embodiment includes control heads 12a, 12b and 12c. During normal reproduction, the phase of the capstan motor 14 is controlled based on the control signal CTL read by the control head 12a. During slow reproduction or frame-by-frame reproduction in the SP mode, the control signal CTL read by the control heads 12a and 12b. The tracking is adjusted on the basis of the control heads 12a and 12c during slow reproduction or frame-by-frame reproduction in the EP mode.
The tracking is adjusted based on the control signal CTL read by. On the other hand, on the magnetic tape 16, as shown in FIG. 2, a video signal is recorded by a helical scan method, and a control signal CTL is recorded every other field. Therefore, the recording pitch of the control signal CTL in the SP mode is p
₁ (= 1.11 mm), the control head 12
b is n ₁ p ₁ + p _1/2 from the control head 12a
And the recording pitch of the control signal CTL in the EP mode is p ₂ (= 0.37 mm).
When the control head 12c is located away from the control head 12a by _{n 2 p 2 + p 2/} 2. The control signal CTL is read at the timing shown in FIG. 3 by the control head 12a and the control head 12b or 12c arranged as described above, and is input to the motor control circuit 22 via the switches 18 and 20. At the time of normal reproduction, the motor control circuit 22 controls the phase of the capstan motor 14 by comparing the phase of the reproduction control signal CTL with the clock (30 Hz) inside the motor control circuit 22. Capstan motor 1 based on the output capstan FG signal
4 is speed-controlled. On the other hand, during slow reproduction or frame-by-frame reproduction, the capstan motor 14 is driven by the one-field feed operation instruction signal output from the system control circuit 24, and the capstan motor 1
4 to adjust the tracking based on the control signal CTL reproduced by driving. The motor control circuit 22 controls the capstan motor 14 based on a key input signal input from a remote controller (not shown) via the system control circuit 24 (phase control during normal reproduction and slow reproduction or frame advance). (Tracking adjustment during reproduction) is switched, and the feed amount of the magnetic tape 16 when the one-field feed operation instruction signal is given is switched based on the mode switching signal output from the system control circuit 24. The mode switching signal is also supplied to a switch 20, and the switch 20 is connected to the terminal 20a when the reproduction mode is the SP mode, and is connected to the terminal 20b when the reproduction mode is the EP mode. The video signal recorded on the magnetic tape 16 sent by the capstan motor 14 is read by the R azimuth heads R and R 'and the L azimuth heads L and L' mounted on the cylinder 26.
And the video signal read by L '
a and 28b are applied to the switch 30, and the video signals read by the heads L and R 'are applied to the switch 32 via the amplifiers 28c and 28d. The video signal output from the switches 30 and 32 is then passed through a switch 34 to a video signal processing circuit 36.
Given to. The signal processed by the video signal processing circuit 36 is output from the output terminal 38. An FG signal and a PG signal are output from the cylinder 26 and supplied to an RF switching pulse generating circuit 40. The RF switching pulse generation circuit 40 generates an RF switching pulse based on the FG signal and the PG signal, and supplies it to the switch 34 as a control signal and to the switch 44 directly and via the NOT circuit 42. RF switching pulse generation circuit 40
Also supplies an RF switching pulse to the system control circuit 24. The system control circuit 24 uses this R
Based on the F switching pulse and the key input signal,
In addition to providing a one-field feed operation instruction signal to the motor control circuit 22, the video signal processing circuit 36 and the switch 44
Outputs an azimuth switching signal to the
8 is supplied with a mode control signal for designating a normal reproduction mode, a slow reproduction mode or a frame-by-frame reproduction mode. That is, the system control circuit 24 outputs an azimuth switching signal and a mode control signal synchronized with the azimuth switching signal on the basis of the RF switching pulse during slow reproduction or frame-by-frame reproduction, and instructs one-field feed operation at a predetermined timing. Output a signal. During normal reproduction, an azimuth switching signal is output based on the RF switching pulse, and the switch 18 is connected to the terminal 1.
8a to output a high-level mode control signal. The video signal processing circuit 36 switches the processing of the color signal by the azimuth switching signal. Switch 4
4 is connected to terminal 44a when the azimuth switching signal is at a high level, and connected to terminal 4a when the azimuth switching signal is at a low level.
4b. The signal output from switch 44 is applied to terminals 30 and 32 as a head switching signal. Switches 30 and 32 are connected to terminals 30a and 32a when the head switching signal is at a high level, and are connected to terminals 30a and 32a when the head switching signal is at a low level. Connected to terminals 30b and 32b. For the mode switching signal, the system control circuit 24 controls the control head 1 during normal reproduction.
By detecting the period of the control signal CTL read by 2a, it is determined whether the mode is the SP mode or the EP mode and output. In operation, when a normal reproduction signal is input from the remote controller to the system control circuit 24, the system control circuit 24
2 and the mode control signal as shown in FIG. Therefore, the motor control circuit 22 controls the phase of the capstan motor 14 based on the normal reproduction signal and the control signal CTL reproduced by the control head 12a as shown in FIG. 4 (F), and performs the capping based on the capstan FG signal. The speed of the stun motor 14 is controlled. On the other hand, the FG signal output from the cylinder 26 and the PG
Based on the signal, a switch outputs a signal shown in FIG. 4B and is provided to switches 34 and 44 and system control circuit 24. System control circuit 2
4 outputs an azimuth switching signal as shown in FIG. 4C based on the input RF switching pulse. Since the switch 44 is controlled by the azimuth switching signal, the switches 30 and 32 are supplied with a head switching signal as shown in FIG. As a result, the head shown in FIG.
A video signal read by tracing the video track shown in (A) is provided, and is output from the output terminal 38 through predetermined processing. When a slow reproduction signal is input to the system control circuit 24 during normal reproduction, the system control circuit 24
2 is supplied with a one-field feed operation instruction signal and a mode switching signal, and a switch 20 is also supplied with a mode switching signal. System control circuit 24
After the one-field feed operation instruction signal is output, the level of the azimuth switching signal and the mode control signal for the switch 18 are switched in synchronization with the fall or rise of the first RF switching pulse. That is, after the system control circuit 24 outputs the field feed signal as shown in FIG. 5 (G), it synchronizes with the first falling or rising of the RF switching pulse shown in FIG. 5 (B). As shown in (E), the levels of the azimuth switching signal and the switch control signal are switched. Thereby, the reproduction control signal CTL is given to the motor control circuit 22 as shown in FIG. 5 (F), and the motor control circuit 22 adjusts the tracking by this. The head switching signal output from the switch 44 according to the azimuth switching signal is shown in FIG.
And the video signal processing circuit 3
6 is supplied with a video signal reproduced by tracing the video track as shown in FIG. 5A by the head shown in FIG. 5H. When a frame feed signal is supplied to the system control circuit 24, a one-field feed operation instruction signal is output from the system control circuit 24 simultaneously with the input of the frame feed signal. Since the video tape recorder 10 operates almost in the same manner as the slow reproduction shown in FIG. 5, detailed description will be omitted. According to this embodiment, the tracking is adjusted by the control head 12b or 12c reading the control signal CTL at the time of slow reproduction or frame-by-frame reproduction, so that noise generation at the time of slow reproduction or frame-by-frame reproduction can be reduced with a simple circuit configuration. Can be prevented. In this embodiment, the control heads 12a, 12b and 12c are arranged at predetermined intervals. However, in consideration of the bending of the magnetic tape 16, it is preferable that the rotary post 46 and the capstan motor 14 be used. _{between, n 1 p 1 + p 1} /2 and n ₂ p ₂ + p
_The control head 12 is adjusted to satisfy the condition of 2/2.
a, 12b and 12c should be placed. In this embodiment, control heads 12b and 12c have been described. However, the present invention is not limited to this case, and head gaps 46a and 46b are provided in control head 46 shown in FIG. Of course, the present invention can also be applied to a case where the control signal CTL read by 46b is applied to the terminals 20a and 20b. However, the interval between the head gaps 46a and 46b is 1 mm or more,
The width W1 of the head 46 needs to be 8.5 mm or more.
The present invention is also applicable to a case where heads 48 shown in FIG. 7 are provided with head gaps 48a, 48b and 48c, and control signals CTL read by the respective heads 48a, 48b and 48c are applied to terminals 18a, 20a and 20b. Of course, it can also be applied. However, also in this case, the interval between the heads 48a, 48b and 48c needs to be 1 mm or more. Further, in this embodiment, at the time of slow reproduction,
Although the track having the azimuth angle L is traced four times and the track having the azimuth angle R is traced five times, the present invention can be applied to the case where the tracks of the L azimuth and the R azimuth are traced the same number of times. Of course, the number of times of tracing may be set arbitrarily.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is an illustrative view showing a recording state of a magnetic tape; FIG. 3 is a timing chart showing a reproduction timing of a control signal CTL. FIG. 4A is an illustrative view showing a head trace;
(B) is a waveform diagram showing an RF switching pulse,
(C) is a waveform diagram showing the azimuth switching signal, (D)
7A is a waveform diagram showing a head switching signal, FIG. 7E is a waveform diagram showing a control signal of the switch 18, FIG. 7F is an illustrative view showing a reproduction control signal CTL, and FIG. FIG. 2H is an illustrative view showing a reproducing head. FIG. 5A is an illustrative view showing a head trace;
(B) is a waveform diagram showing an RF switching pulse,
(C) is a waveform diagram showing the azimuth switching signal, (D)
7A is a waveform diagram showing a head switching signal, FIG. 7E is a waveform diagram showing a control signal of the switch 18, FIG. 7F is an illustrative view showing a reproduction control signal CTL, and FIG. FIG. 2H is an illustrative view showing a reproducing head. FIG. 6 is an illustrative view showing a part of another embodiment of the present invention; FIG. 7 is an illustrative view showing a part of another embodiment of the present invention; [Description of Signs] 10 Video tape recorders 12a, 12b, 12c, 46, 48 Control head 14 Capstan motors 18, 20, 30, 32, 34, 44 Switch 22 Motor control circuit 24 System control circuit 26 ... cylinder 40 ... RF switching pulse generation circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 15/467 G11B 15/46

Claims (1)

(57) [Claims] [Claim 1] Recording on magnetic tape by helical scan method
To the scanned video track and to the head switching pulse
A plurality of reproduction heads selectively enabled based on the first control head for reading control signals recorded at a pitch corresponding to two video tracks in a length direction of the magnetic tape; and one video from the first control head. Distance corresponding to the truck
And a second control for reading the control signal.
Control head, one of the first control head and the second control head.
Switching means for selecting, on the control head selected by said switching means
Therefore, tracking is performed based on the read control signal.
Adjusts and responds to the periodic feed operation instruction
Write the magnetic tape over a distance corresponding to one video track.
And a feed operation finger
Response to the first level change of the head switching pulse after
A switch for switching the selection of the switching means.
A magnetic recording / reproducing apparatus, comprising: