JPS61220573A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a stable reproducing signal without fail by detecting the displacement quantity of a bimorph plate and controlling the timing when a dummy vertical synchronizing signal is formed according to the detected value. CONSTITUTION:The drive voltages of the bimorph plates 23a and 23b from drive circuits 22a and 22b are detected, and according to the voltages the formation position of the dummy vertical synchronizing signal is changed to insert said signal at the prescribed position in synchronizing with the reproducing signal. Namely the drive voltages from the drive circuits 22a and 22b are supplied to a switch circuit 25 through attenuators 24a and 24b. The output of the switch circuit 25 is applied to a comparator 31 through a sample holding circuit 26 and an inverting amplifier 28, and the comparator 31 compares the output with a lamp signal relating to the timing of a video signal detected by a detecting circuit 11. Then a monostable multivibrator 32 forms the dummy vertical synchronizing signal, which is supplied to an adder 33 and inserted into the reproduced video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device in which dynamic tracking correction is performed using a bimorph plate.

[Overview of the invention]

The present invention relates to a magnetic recording and reproducing device in which dynamic tracking correction is performed using a bimorph plate.
By detecting all the drive voltages of the bimorph plate and controlling the timing of forming a pseudo vertical synchronization signal according to this detected value, a stable reproduction signal can always be obtained.

[Conventional technology]

A video Teso recorder that performs dynamic tracking correction using a bimorph plate (electromechanical transducer) has been proposed. For example, in a so-called 8mm video tape recorder, pilot signals of four frequencies f, ~f4 are superimposed on each track during recording, as shown in FIG. It has been proposed to perform dynamic tracking by detecting the crosstalk of Ilot Tsukuda.

That is, in Fig. 6, the input terminals (IV) (IA)
The video signal and the audio signal from the are supplied to the recording circuit (2), and the video signal that has been subjected to predetermined low frequency conversion etc. is provided alternately in each field, and in front of each field, the video signal and the audio signal are provided in each field.
The audio for one field is converted into PCM, and first and second recording signals are formed in which the audio signals are time-base compressed. These recording signals are sent to adders (3a) (3b), respectively.
), rotary heads (
5a) (5b).

Furthermore, a magnetic tape (6) is wound along the rotating circumferential surface of these heads (sa) (5b) within a range of, for example, 216 degrees, and while this tape (6) is transported at a predetermined speed, the heads (sa) (5b) 5a) (5b) is rotated at a predetermined phase, an audio signal is recorded in the first 36 degree period of each track, and a video signal is recorded in the second half 180 degree period, and these tracks are sequentially transferred to the tape (6). are formed in parallel in the longitudinal direction.

Furthermore, the above-mentioned four-frequency A'irot signal generation circuit (7)
is provided. Here, the frequencies of the pilot signals are determined to be f1=102.54 kHz, f2'', 118.95 kHz, f3'', 165.21 kHz, and f4=148.69 kHz, respectively. Four-frequency signals from this generation circuit (7) are supplied to a switch circuit (8). In addition, a recording/reproduction switching signal is supplied to the switch circuit (8) through the terminal (9), and the rotational phase of the rotary head (5a) (5b) is determined by a pulse generator ill and a detection circuit provided on the rotary shaft. 01) and is supplied to the switch circuit (8). As a result, from the switch circuit (8), f1→f2→
A signal that changes and is repeated in the order of f5→f4→f1→... is extracted. This pilot signal is passed through the record/playback switch 02 to the adder (3
a) Supplied to (3b).

As a result, a pilot signal that changes in the above-mentioned order is recorded on each recording track in a manner superimposed on video No. 16. Note that the pilot number of the previous track is superimposed on the audio signal period.

During playback, first the tape (6) is read from the head (5a).
) (5b) is transmitted to the switch (4a) (4
b) is supplied to the reproduction circuit 03), and a video signal subjected to a predetermined high-frequency inverse conversion, etc., and an audio signal subjected to PCM demodulation and time axis expansion are taken out to an output terminal (14V) (14A).

Furthermore, the reproduced signals from the switches (4a) and (4-b) are supplied to the Ronos filters (15a) and (15b), respectively, which pass the frequencies f1 to f4 of the above-mentioned zoirot signal, and these filters (15a) The signal from (15b) is fed to multipliers (16a) (16b).

Furthermore, when a signal indicating the reproduction state is supplied to the switch circuit (8) through the terminal (9), the frequency order of the pilot signal taken out from the switch circuit (8) is changed,
f, → with the same phase as f, → f2 → f3 → f4 → during recording
It is made to change as f4→f2→f3→. This signal passes through the multiplier (16m) (16b
).

Therefore, from these multipliers (16m) (16b),
The armpit signal in the reproduced signal is multiplied by the signal from the switch circuit (8), and a signal having a frequency that is the difference between the respective frequencies is extracted. Here, the playback signal is being played! The pilot signal includes the original pilot signal of the track being reproduced as well as the pilot signal of crosstalk from adjacent tracks as shown in the table of FIG. When the above-mentioned multiplication is performed on the pilot signals of these crosstalks, the crosstalk from the tracks on the side of the tape in the traveling direction is approximately 46kHz, and the crosstalk from the tracks on the opposite side is approximately 16kHz.
A signal of z is formed.

Therefore, these signals are passed through a pantono 4-sphere filter (17&).
(17b Signals are formed according to the distance, and these signals are further transmitted to a differential amplifier (21a).
(21b,), and a signal corresponding to the difference in distance is formed. These signals are connected to the drive circuit (2
2a) (22b) through head (5a) (5b)
Bimorph plates (23a) (23b) provided at the base of
). Control is then performed so that the difference between the respective distances becomes "0".

This performs dynamic tracking during playback. That is, the position of the heads (5a) (sb) is corrected so that it always passes through the center of the reproduction track, and a good reproduction signal can always be obtained.

By the way, in this apparatus, by changing the transport speed of the tape (6) during playback from that during recording, variable speed playback such as slow motion playback and double speed playback can be performed. That is, FIG. 8 shows the bimorph plate (23) of the tape (6).
m) When (23b) is not driven, the centers of the respective heads (5a) and (5b) are scanned as shown by solid lines (1) to (2). On the other hand, when the above-mentioned tracking correction is performed, each scanning trajectory becomes a double line ■'
As shown by ~■', the center of the heads (5a) and (5b) is located at the center of the reproduction track, and a low reproduction signal can be obtained. Note that dynamic tracking is generally not performed during the audio signal period during variable speed playback, so the audio signal portion is omitted from the diagram for convenience.

However, in this case, the vertical synchronization signal in the recorded video signal is provided, for example, at the 7H (H is a horizontal period) from the start of the video signal on the tape, as shown with diagonal lines. There is. On the other hand, as described above, dynamic tracking during variable speed playback is performed only during the video No. 41 period. For this reason, tracking correction is not completely performed at the beginning of the video signal period during variable speed playback, and the playback signal cannot be stably obtained, resulting in the above-mentioned vertical synchronization signal not being played properly and being dropped. The fear was extremely high.

Therefore, a pseudo vertical sync signal is generated just before the vertical sync signal on the tape is completely reproduced, and this pseudo vertical sync signal is inserted into the playback signal so that vertical synchronization in the playback signal can be stably obtained. was considered. In this case, with devices that do not perform conventional dynamic tracking,
Since the rotational phase of the head and the recorded position of the video signal on the tape remain unchanged, the rotational phase is detected and a pseudo vertical synchronization signal is formed, and the pseudo vertical synchronization signal can be inserted successfully.

However, when tracking correction is performed as described above, when the head is moved, a deviation will occur between the rotational phase of the head and the recording position of the image (i). In the figure, when ■ is corrected to ■', a -IH deviation occurs at the starting edge and at ■ → ■'.Therefore, even if the pseudo vertical synchronization signal is generated by detecting the rotational phase of the head as described above, Its position is asynchronous with the video signal, and when such a pseudo vertical synchronization signal is inserted into the playback signal, the receiver performs deflection based on this pseudo vertical synchronization signal, so the above-mentioned The image is vibrated up and down by the amount of deviation, resulting in an extremely unsightly screen.Although the top is relatively neat,
If this is set to an arbitrary value, the amount of deviation becomes even more complicated.

[Problem that the invention seeks to solve]

Conventional devices were constructed as described above. For this reason, when tracking correction is performed during variable speed playback, the position of the pseudo vertical synchronization signal is shifted, causing the video to vibrate up and down, making the screen extremely difficult to view.

[Means for solving problems]

The present invention provides a magnetic recording and reproducing apparatus that uses electromechanical transducers (23a) and (23b) to control the curvature of the heads (5a) and (5b) so that correct tracking is always performed even during variable speed reproduction. A signal indicating the rotational phase of the head (detection circuit (Ill)) is delayed (ramp generation circuit (3 (9, comparison circuit C31)) to form a pseudo vertical synchronization signal at a timing earlier than the vertical synchronization signal in the reproduced signal. is inserted into the playback signal (adder a), and also detects the drive voltage of the electromechanical transducer (sample hold circuit 06) and adjusts the delay for forming the pseudo vertical synchronization signal according to this detected value. This is a magnetic recording and reproducing device that controls the scenery.

[Effect]

According to this device, a stable image can always be obtained by detecting the displacement value of the bimorph plate and controlling the position of the pseudo vertical synchronization signal according to the displacement value.

〔Example〕

By the way, the above-mentioned bimorph plate ("Kikiro conversion element") 7
1i: when performing dynamic tracking using, for example, the driving voltage of the bimorph plate when performing three types of tracking correction as shown in A in FIG. 2, as shown in B in the same figure. On the other hand, when this tracking correction is performed, the amount of deviation between the rotational phase and the recording position is changed as shown in D in the figure, for example, with respect to the rotational phase of the recording position a as shown in C in the figure. As is clear from this figure, the voltage at the starting end of the drive voltage and the amount of deviation of the recording position are -
It is supported by the following function.

Therefore, by detecting the drive voltage of the bimorph plates (23a) (23b) from the above-mentioned drive circuits (22a) (22b) and changing the formation positions of the pseudo-vertical and synchronization signals according to this voltage, the playback signal can be adjusted. A pseudo vertical synchronization signal can be inserted at a synchronized predetermined position.

That is, in FIG. 1, the drive circuit (22a) (2
Each driving voltage from the attenuator (24a) (2b)
4b) to form signals as shown at B and C in the time chart of FIG. 3, respectively. The Naori im chart corresponds to the above-mentioned i-slow case.

These signals are supplied to Q switch circuits.

Further, a switching pulse as shown in A of the time chart corresponding to the eirin period of the head (5a) (5b) from the detection circuit (detection circuit) is supplied to the switch circuit (29).
A signal as shown in D in the time chart is generated from this switch circuit (25).

This signal is supplied to the sample and hold circuit QQ, and the switching pulse from the detection circuit αυ is supplied to the sampling pulse generation circuit 0η, so that a sampling pulse as shown in F in the time chart corresponding to the start of each switching of the switching pulse is generated. is formed and supplied to a sample and hold circuit Q6). Then, this sample hold signal (im signal) is inverted by an inverting amplifier (c), and its level is adjusted by a rheum signal (291) to form a signal as shown at E in the time chart.

Generating circuit C again! The sampling pulse from η is supplied to the ramp generation circuit (to) to form a ramp signal as shown at G in the time chart.

This lamp signal and amplifier G! The signal from υ is supplied to the comparator circuit 01). As a result, a signal as shown at H in the time chart is generated from the comparator circuit Gυ, and this signal is supplied to the monomulti 021, which generates a pseudo vertical synchronization signal whose formation position is changed as shown in the time chart. is formed.

This signal is supplied between adders provided on the video output side of the reproduction circuits a~ and inserted into the reproduced video signal.

As a result, even if tracking correction is performed during variable speed playback,
A pseudo vertical synchronization signal that is always synchronized with the playback signal is formed,
By inserting this signal, a stable image can always be obtained. Note that this device can always obtain a pseudo vertical synchronization signal synchronized with the playback signal even during motion playback or double speed playback.

Further, FIG. 4 shows a specific circuit example of the above-mentioned device, and parts corresponding to those in the above-mentioned configuration diagram are indicated with the same reference numbers. Note that 0
The best option is a mono multi for signal delay.

This circuit can form the above-mentioned pseudo vertical synchronization signal.

〔Effect of the invention〕

According to the present invention, the displacement of the bimorph plate: im is detected;
By controlling the position of the pseudo vertical synchronization signal according to its amount, it is now possible to always obtain stable images.

[Brief explanation of the drawings] Fig. 1 is a configuration diagram of an example of the present invention, Figs. 2 to 4 are diagrams of its appearance, and Figs. It is a diagram. (5a) (5b) is the head, (13) is the reproduction circuit, (1
4A) (14V) is the output terminal, α1) is the rotational phase detection circuit, (22a) (22b) is the drive circuit, (23
a) (23b) is a bimorph plate, (24m) (24
b) is an attenuator, ta is a switch circuit, (a) is a sample hold circuit, (27) is a sampling/sampling generation circuit, (2) is an amplifier, and (2) is ? Rhium, α
02 is a ramp generating circuit, (3) is a comparison circuit, 02 is a monomulti, and α is an adder.

Claims (1)

[Claims] A magnetic recording and reproducing device that uses an electromechanical transducer to control the height of a head so that accurate tracking is always performed even during variable speed reproduction, in which a signal indicating the rotational phase of the head is delayed. to form a pseudo vertical sync signal at a timing earlier than the vertical sync signal in the reproduced signal and insert it into the reproduced signal, and also detect the drive voltage of the electromechanical transducer and convert the pseudo vertical sync signal according to this detected value. A magnetic recording/reproducing device configured to control the amount of delay for forming a synchronization signal.