JP2722658B2 - Rotating head type magnetic recording and playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording field which is formed by using a pair of rotating heads having different azimuth angles alternately, as a recording trajectory inclined with respect to the longitudinal direction of a magnetic tape. The present invention relates to a rotary head type magnetic recording / reproducing apparatus that sequentially records and reproduces video signals of different speeds. The configuration is such that an image can be stably obtained.

2. Description of the Related Art In recent years, there has been an increasing demand for a special (shift) reproduction function for reproducing at a tape speed different from that at the time of recording in a rotary head type magnetic recording / reproducing apparatus. However, an apparatus has been proposed which realizes linear reverse 1/2 slow reproduction without noise while running the tape at a constant speed of 1/2 at the time of recording at the time of reproduction in the opposite direction to the time of recording. Absent.

During reproduction, when the magnetic tape is run in a direction opposite to the direction of recording at a constant half speed of recording, two recording tracks having the same azimuth angle in one field are simultaneously recorded. Since an output signal to be reproduced is obtained, noise due to adjacent beats is output at the center of the screen, making the screen very difficult to see, or the reproduced output signal near the center of the screen is minimized, resulting in a screen with poor image quality.

The present invention has been made in view of the above point, and an object of the present invention is to provide a rotary head type magnetic recording / reproducing apparatus capable of natural noiseless reverse 1/2 slow reproduction with natural movement.

Means for Solving the Problems In order to solve the above problems, a rotary head type magnetic recording / reproducing apparatus according to the present invention comprises first and second magnetic heads having different azimuth angles.
And a second head pair including third and fourth rotary heads having the same azimuth angle as the first and second rotary heads, respectively. At the time of reproduction, while traveling in a direction opposite to that at the time of recording at a constant speed of half the traveling speed at the time of recording,
There is provided a means for compensating for the field section in which the reproduction output signal of the first head pair has decreased by using the reproduction output signal of the second head pair in units of one field.

According to the present invention, the use of the first rotating head pair and the second head pair is alternately switched every two fields by the above-described configuration, so that a good reproduction output signal is always obtained in each field. Noiseless reverse 1 / with smooth movement
2 Slow playback function is realized.

Hereinafter, a rotary head type magnetic recording / reproducing apparatus according to the present invention will be described with reference to the illustrated embodiments. FIG. 1 is a diagram showing a main part of an embodiment of the present invention, and FIG. 2 is a diagram showing a recording track pattern of a magnetic tape on which azimuth recording is performed and a half of the recording track pattern during recording.
It shows the relationship with the trajectory of the reproducing head when the recording and reproducing operation is performed in the opposite direction from that during recording at a constant speed. FIG. 3 is an operation waveform diagram in the embodiment of the present invention.

In FIG. 1, T1 is a first rotary head having an azimuth angle of + 6 °, and K2 is a third rotary head having an azimuth angle of -6 °. T2 is another second rotary head having an azimuth angle of -6 °, and K1 is another fourth rotary head having an azimuth angle of + 6 °. The first
The second rotary heads T1 and T2 are arranged 180 ° apart from each other with respect to the rotation center of the rotary drum 3 to form a first head pair. Third and fourth rotary heads K2 and K1
Are also arranged 180 ° apart from each other to form a second head pair.

The first and second head pairs are mounted on the same rotating plane of the rotating drum 3 as shown in FIG. 1, for example, separated by a distance corresponding to two horizontal synchronizing signal periods of the video signal. The rotating drum 3 is driven by a motor 5 via a rotating shaft 4.
As a result, it is rotated at a rotation speed of 1800 rpm in the direction of arrow 9. The magnetic tape 6 is guided by the guide posts 7 and 8 and is helically wound around the rotary drum 3 over 180 ° or more.
And can be driven with capstan 12. FIG. 2 shows a schematic track pattern of the magnetic tape 6.
In FIG. 2, each of the parallelograms R0, L1, R1, L2, R2... Represents a recording track of one field, and R is + 6 °.
L represents a track recorded by the first rotary head T1 having an azimuth angle of -6 °, and L represents a track recorded by the second rotary head T2 having an azimuth angle of −6 °. (Recorded order). That is, R0 → L1
→ R1 → L2 → R2 → L3 → R3 → L4 → R4..., And the same recording track is overlapped in the horizontal direction. Note that the first and second rotary heads M1 and M2 are configured to partially overlap the recording trajectory of the other rotary head previously recorded at the time of recording, and to sequentially record while erasing the overlapped portion. 21, 23, and 25 represent the locus of the lower end of the head during reverse 1/2 slow reproduction, and 22, 24, and 26 represent the locus of the upper end of the head during reverse 1/2 slow reproduction. Accordingly, 21 to 22, 23 to 24, and 25 to 26 correspond to the width of the reproducing head, and a reproduced output signal is obtained only at a portion where the azimuth angles of recording and reproducing coincide. That is, the vertical line portion shown in FIG. 2 is a reproduction output signal, and the magnitude is indicated by the vertical length of the vertical line portion. 2a is a head trajectory of the first head pair during reverse 1/2 slow reproduction, FIG. 2b is a head trajectory of the second head pair during reverse 1/2 slow reproduction, and FIG. c is the head trajectory of the first head pair and the second head pair during reverse 1/2 slow reproduction in the present invention. The third rotary head K2 is the first rotary head.
Since it is mounted close to T1 (in this embodiment, separated by a distance corresponding to two horizontal synchronizing signal periods of the video signal), the reproduction head locus is almost the same as the first rotary head T1. The fourth rotary head K1 is the second rotary head T2
, The second rotary head T2
And the reproducing head locus is almost the same.

At the time of such reverse 1/2 slow reproduction, the first head pair T1 and T2 have azimuth angles of + 6 ° and -6 °, respectively, so that a reproduction head output signal as shown in FIG. 3D is obtained. . Further, the first rotary heads K1 and K2 are respectively -6.
Since the azimuth angles are + 6 ° and + 6 °, a reproducing head output signal as shown in FIG. 3E is obtained. Normally, these reproduction head output signals consist of an FM-modulated luminance signal having a carrier frequency of about 3.9 MHz and a carrier chrominance signal whose chrominance subcarrier frequency has been down-converted to about 629 KHz. FIG. 3j shows the time scale. This is, t ₀ is shows the field start time, t ₁ indicates a field termination time. That is, about 16.7msec of _{t 0 ~t 1, t 1 ~t} 2 is one field. FIG. 3g shows the head switching signal and the field numbers 100, 101, 102, 103 and 104. In FIG. 3d, in the fields of field numbers 100 and 101, two tracks at different times (in FIG.
At 0, the R1 and R2 tracks, and in the field 101, the L1 and L2 tracks) are played back simultaneously.
The black portion in FIG. 3d is a beat adjacent to each other and reproduced near the center of the screen. Since the adjacent beats are reproduced by two fields per frame, the screen becomes very hard to see. This is a disadvantage of the conventional example. The present invention describes such a field in which the output signal of the reproducing head of the first pair of heads T1 and T2 becomes a low-amplitude signal or a neighboring beat.
By replacing with the reproduction head output signals of the second pair of heads K2 and K1 as shown in FIG. 3e, as shown in FIG. 3f, noise and smooth noiseless movement in which adjacent beats are not possible can be obtained. A reverse 1/2 slow playback screen can be obtained.

The above-mentioned field in which the output of the first pair of heads decreases or becomes adjacent to each other is supplemented by the output of the second pair of rotating heads, so that smooth noiseless reverse 1/2 slow reproduction with no beats is obtained. FIG. 4 is a block diagram showing an embodiment of the present invention capable of obtaining a screen. In FIG. 4, the same components as those described in FIG. 1 are denoted by the same reference numerals. The head output signal of the first rotary head T1 is amplified by the preamplifier 51 and supplied to the gate circuit 52. The output signal of the gate circuit 52 is supplied to the adder 53. The head output signal of the third rotary head K2 is amplified by the preamplifier 61 and supplied to the gate circuit 62. The output signal of the gate circuit 62 is supplied to the adder 53. The output signal of the adder 53 is supplied to the switch circuit 57. The head output signal of the second rotary head T2 is amplified by the preamplifier 54 and supplied to the gate circuit 55. The output signal of the gate circuit 55 is supplied to the adder 56. The head output signal of the fourth rotary head K1 is amplified by the preamplifier 63 and supplied to the gate circuit 64. The output signal of the gate circuit 64 is supplied to the adder 56. The output signal of the adder 56 is supplied to the switch circuit 57. The output signal of the switch circuit 57 is supplied to a video signal demodulator 67, and the output signal of the video signal demodulator 67 is supplied to an output terminal 68. The head switching signal 58 is a signal having a duty synchronized with the rotation phase of the rotary head of 50% and a frequency of 30 Hz, and is supplied to the switch circuit 57 and the 1/2 frequency dividing circuit 59. The output signal of the 1/2 frequency dividing circuit 59 is supplied to the inverter circuit 60, and at the same time, becomes a use command h for the first rotating head pair, and is supplied to the switch circuit 66. An output signal of the inverter circuit 66 becomes a use command i for the second rotating head pair and is supplied to the switch circuit 65. The output signal of the reverse 1/2 slow command circuit 69 is supplied as a control signal to the switch circuits 65 and 66, and selects the use command signals h and i as output signals of the switch circuit 66 only during reverse 1/2 slow playback. To the gate control terminals of the gate circuits 52, 55 and 62, 64.

Next, the operation of the present embodiment will be described with reference to the waveform diagrams of FIG. 2 and FIG. At the time of reverse 1/2 slow reproduction, if the first pair of heads T1 and T2 draws a reproduction head trajectory as shown in FIG. 2A, the first pair of heads as shown in FIG.
The reproduced output signals of T1 and T2 are output from the preamplifiers 51 and 54,
These are supplied to gate circuits 52 and 55, respectively. The second head pair K2, K1 draws a reproduction head trajectory as shown in FIG. 2B, and the reproduction output signal of the second head pair K2, K1 as shown in FIG. It is output from 63 and supplied to gate circuits 62 and 64, respectively. When the output signal of FIG. 3D is output from the gate circuits 52 and 55 as it is,
In the case of 0,101, as described above, the black portions become adjacent beats, and a clear noiseless reverse 1/2 slow reproduction screen is not obtained. FIG. 3g shows the head switching signal 58 of FIG. 4, which controls the switch circuit 57. That is, when the head switching signal 58 is at the high level, the output signal of the switch circuit 57 is added to the adder 53.
When the head switching signal 58 is at a low level, the output signal of the switch circuit 57 becomes the output signal of the adder 56. FIG. 3H shows a use command signal for the first head pair at the time of reverse 1/2 slow reproduction, which controls the gate circuits 52 and 55. That is, when FIG. 3H is at a high level, the gate circuits 52 and 55 are opened, the head output signal of the low-speed rotary head T1 is supplied to the adder 53 via the preamplifier 51, and the low-speed rotary head T2 Is supplied to the adder 56 via the preamplifier 54. FIG. 3i shows a use command signal for the second head pair at the time of reverse 1/2 slow reproduction, which controls the gate circuits 62 and 64. That is, when FIG. 3i is at a high level, the gate circuits 62 and 64 are opened and the high-speed rotary head K
The head output signal of No. 2 is supplied to the adder 53 via the preamplifier 61, and the head output signal of the high-speed rotary head K1 is supplied to the adder 56 via the preamplifier 63. The reverse 1/2 slow command signal 69 controls the switch circuits 65 and 66. That is, at the time of reverse 1/2 slow reproduction, the switch circuit 65 is connected to the use command signal i for the second head pair, and the switch circuit 66 is connected to the use command signal h for the first head pair. During normal playback, the switch circuit 65
Only the reproduction output of the first pair of heads is applied to the adders 53 and 56. Switch circuit 66 is V
Connected to _CC (constant voltage) side. With such a configuration, the output signal of the first rotary head T1 in the field 100 of FIG. 3D is supplemented by the output signal of the third rotary head K2 in FIG. The output signal of the second rotary head T2 in FIG.
And the output signal of the switch circuit 57 becomes as shown in FIG. 3f. This field
Reproduction output is continuously obtained with four fields from 100 to 103 as one cycle. The output signal of the switch circuit 57 is supplied to a video signal demodulator 67 and is converted into a video signal. As is well known, the video signal demodulator 67 is composed of a luminance signal demodulator and a carrier chrominance signal demodulator. The luminance signal demodulation system demodulates the FM-modulated luminance signal, and the carrier chrominance signal demodulation system removes jitter from the reproduced low-frequency modulated carrier chrominance signal and converts it into a carrier chrominance signal. The output signal of the video signal demodulator 67 is supplied to an output terminal 68,
A clear inverted 1/2 slow playback video signal without noise or adjacent beats can be obtained continuously.

In this way, during reverse 1/2 slow playback, the field in which the playback output signal of the first pair of heads is noise or adjacent beats is replaced by the playback output signal of the second pair of heads without noise or adjacent beats. Can be supplemented by signals. As a result, a clear inverted 1/2 slow reproduction screen without noise or adjacent beats is obtained.

Effects of the Invention As described above, the present invention provides the first head pair T1, T
2 and a second pair of hands K2 and K1, and the reproduction output signal of the first pair of heads T1 and T2 decreases during reverse 1/2 slow reproduction.
By replacing the two fields for each frame with the playback output signals of the second pair of heads K2 and K1, smooth noiseless reverse 1/2 slow playback with no noise or motion without adjacent beats becomes possible, and is practical Is extremely useful.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a rotary head type magnetic recording / reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a recording track pattern of an azimuth-recorded magnetic tape and a head at the time of reverse 1/2 slow reproduction. FIG. 3 is a diagram showing an example of a relationship with a trajectory pattern, FIG. 3 is an operation waveform diagram in the embodiment of the present invention, and FIG. 4 is a main part electric circuit diagram of the embodiment of the present invention. T1, T2 ... first and second rotary heads, K2, K1 ... third and fourth rotary heads, 3 ... rotary drum, 6 ... magnetic tape, 5
1,54,61,63 ... preamplifier, 52, 55, 62, 64 ... gate circuit, 53, 56 ... adder, 57, 65, 66 ... switch circuit, 59
… 1/2 frequency divider, 60… Inverter circuit, 67… Video signal demodulator, 68 …… Output terminal.

Claims (1)

(57) [Claims] A first head pair that is different from the first head pair;
Head type magnetic field for sequentially recording a video signal of one field as a recording trajectory inclined with respect to the longitudinal direction of the magnetic tape by using a pair of rotary magnetic heads having an azimuth angle of a second angle and a second azimuth angle alternately. A recording / reproducing apparatus, comprising: a pair of rotating magnetic heads having a first and a second azimuth angle forming a second head pair, near each rotating magnetic head forming the first head pair. A rotating magnetic head having an azimuth angle different from the azimuth angle of the rotating magnetic head is located at each position, and is arranged so as to scan the recording locus of the rotating magnetic head of the first head pair. When the head is driven in the reverse direction at half the speed of the reproduction and the reproduction is performed, the reproduction output of the first head pair and the second head pair are alternately and selectively taken out every two fields, and are continuously reproduced. Rotary head type magnetic recording reproducing apparatus characterized by a video signal.