JPS63155967A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the disorder of a pattern at the transition from the still mode to the PLAY mode by reading contents of a filed memory and using it as a video output until a control lock of a capstan motor is detected and outputting a reproduced video signal after the phase control of the capstan motor is locked. CONSTITUTION:The speed control of a capstan motor is executed by using an output signal from a frequency generator FG fitted to the capstan motor and the servo of the capstan mode is locked after a pulse wave of address clear ADR.CLR is outputted first after a pause key is depressed since a control signal recorded on a control track 16 is used for a phase comparison signal in the phase control at the reproduction mode. While a RE/inverse of WE signal is in the readout mode, a still picture of the field No.2 is reproduced, the pause key is depressed and the PLAY mode is attained again and the phase control of the capstan is locked and the reproduced video signal is outputted from the start of field, then the disorder at changeover of a picture is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a segment recording type magnetic recording and reproducing apparatus that realizes still reproduction.

In conventional technology-a, a helical scan type magnetic recording/reproducing device (hereinafter referred to as VTR) has a cylindrical head drum 18d:'
A pair of heads are installed at opposing positions with different azimuth angles, and a running magnetic tape is wound around the rotatably driven head drum in a helical shape more than 1800 times, and the head is moved in contact with the running magnetic tape in the diagonal width direction. By doing so, video signals are recorded and played back.

When performing special reproduction by running the tape at a speed different from that during normal reproduction, if the recording head is used as is, the head output will decrease due to the difference in azimuth, resulting in a significant deterioration in image quality.

For still playback among special playbacks, as shown in Figure 10, the standard mode recording sickle playback head 5PC) 11.S
P CH2 and special playback head LPCH1/LPCH
2, recording/reproducing head 5PCH1/$P
Video track 2 when recorded by CH2 is the 12th
The result will be as shown in the figure.

During normal playback, the recording and playback heads 5PCH1 and 5PCH2
During still playback, the head scans over the video track 2 along a head trajectory as shown in FIG. Here, the special playback head LPC) I2 and the recording/playback head 5PCH2 have the same azimuth, and by switching the playback outputs from the recording/playback head 5PCH2 and the special playback head LPCH2 as shown in FIG. ) can be obtained, and thus a field still playback mode can be realized. However, the conventional example described above is an example of field still playback when one field is recorded on one track. 1st
Figure 3 shows an example of segment recording. Here, the video signals of 41 fields are A1, B1, and C of video track 2.
I) Records are divided into racks. Further, the video signal of the A2 field is divided and recorded into A2, B2, and C2 tracks. In this case, head trajectory 3 with the tape stopped only scans the B1 track;
It is not possible to regenerate the entire field.

Therefore, it is conceivable to apply a special playback circuit using a field memory shown in FIG. 14 to still playback using the segment recording method. Special reproduction circuits using field memory have recently been incorporated into consumer VTRs as the price of memory has declined. The operation of this circuit will be explained using the circuit diagram shown in FIG. The timing of writing and reading from the field memory 4 is controlled by the system microcomputer 6 using the address clear (ADH-CLR) signal as a reference, and is performed in units of one field by the read/write control signal (RE/■). Address clear (ADH
-CLR) signal is created by a pseudo head switching pulse and is output even if the cylinder is not rotating, and the memory address counter in the timing generator 6 is reset by this signal. From this point on, one field (!, 5H) is written to or read from memory by the read/write mode (RE/WE).

The timing generator 5 outputs field memory control signals (OE, WE, RAS, CAS).

When obtaining continuous images using a field memory, the continuity of each field in the synchronization system becomes a problem. In other words, the continuity of even and odd fields is 1 field H8 Ayu when reading from the memory. This can be obtained by setting the h number to 263.262.

FIG. 16 shows a timing chart of still playback operation using field memory. FIG. 15(,) shows the track pattern of the video track 2 on the magnetic tape 1. In FIG. In the figure (b), a transition is made from the PLAY mode to the STILL L mode at the timing shown in the figure (e) by head switching, and the tape speed changes as shown in the figure (d).

After time T1, the tape speed decreases and the head output becomes small because the head locus cannot cover a predetermined track portion. Until time T2, the head output signal is written into the field memory, but after time T2, the field memory is set to read mode, and a stable still playback image can be obtained.

Problems to be Solved by the Invention However, in the still playback method using the field memo Vt described above, when transitioning from still mode to PLAY mode, the screen becomes distorted while the cylinder motor and capstan motor are not synchronized. There is a point.

FIG. 16(a) shows a track pattern in which one track is recorded in one field. A control tracker is provided at the bottom end of the magnetic tape 1, and each field has an S pole and a control tracker.
The N pole is switched and recorded.

FIG. 16(g) shows an example of segment recording in which one field is recorded on three tracks. In this case, in the control track 7 at the lower end of the magnetic tape 1, the S pole and N pole are switched every field, that is, the S pole is switched every three tracks.
A control signal that switches between pole and north pole is recorded. Is the reproduction phase of the capstan motor controlled using the control signal recorded on this control track 7?
However, in the case of the segment recording shown in FIG. 16(b), the rotational speed of the capstan motor must be tripled in order for the period of the control signal to be the same as that in FIG. 16(a). However, if the motor rotational speed is tripled, the time required for the speed control and phase control of the capstan motor to be engaged becomes longer. In other words, when the pause button is pressed from the still mode and the mode shifts to the PLAY mode, reading from the field memory is stopped and the mode shifts to normal playback, the reproduced image will be distorted until the capstan motor's speed control and phase control are pulled in. . In view of the above, an object of the present invention is to provide a segment recording type magnetic recording/reproducing apparatus in which the reproduced image is not disturbed when switching from the still reproduction mode to the normal reproduction mode.

Means for Solving the Problems In order to achieve the above object, a magnetic recording/reproducing apparatus according to the present invention has two heads having different azimuth angles mounted on a rotating drum at positions 180° opposite each other, and each head is attached to a running tape. In a magnetic ball distribution playback device in which track patterns are formed diagonally and alternately in the longitudinal direction of the entire tape, and one field is recorded and played back in multiple tracks, the playback video signal output from the head during playback is digitalized. an A/D converter for converting into a value, a recording means for storing all the reproduced video signals converted into digital signals, and a D/A converter for converting all the video information data stored in the storage means into analog signals; A timing generator for controlling the address and writing/reading of the storage means, a capstan motor control pull-in detection circuit for detecting that the capstan motor phase control has pulled in, and an output of the capstan motor control pull-in detection circuit. It is composed of a system microcomputer that receives a capstan motor control pull-in detection signal as input and controls writing/reading of the storage means.

According to the above-described configuration, the present invention reads the contents of the field memory until the control pull-in of the capstan motor is detected by the output of the capstan motor control pull-in detection circuit when the mode shifts from the still playback mode to the normal playback mode. By outputting the reproduced video signal only after the phase control of the capstan motor is pulled in, it is possible to prevent screen disturbances when transitioning from the still mode to the PLAY mode.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to illustrated examples.

FIG. 1 is a circuit block diagram showing a first embodiment of the present invention. Writing to field memory 9, which is a storage means
Read timing is address clear (ADH-CL)
R) signal as a reference, the reading/writing control signal (RE/WE) controlled by the system microcomputer 12 is used in units of one field. Since the address clear (ADH/CLR) signal is generated from a pseudo head switching pulse, it is output even if the cylinder is not rotating, and the memory address counter in the timing generator 1o is reset by this signal. Read/write mode from this point RE /W
Data for the field (262, 5H) is written to or read from the field memory 9 by E.

The timing generator 8 outputs control signals (OE, WE, RAS, CAS) for the field memory 9.

FIG. 2 shows a tape pattern during segment recording. Video tracks 17 are formed on the magnetic tape 15, and in this example, three tracks constitute one field. That is, A1・
Record field grave 1 on A2 and A3 tracks, and record field grave 1 on B1 and A3 tracks.
Record field /I62 on B2 and B3 tracks, and
Field A3 is recorded on tracks 1, C2, and C3. Here, on a control track 18 provided at the lower end of the magnetic tape 15, N-pole and S-pole are switched and recorded every field.

FIG. 3 shows a timing chart for explaining the operation of the first embodiment of the present invention. First, in the PLAY mode, the reproduced video signal is directly output as a video signal through the switch 14 ((6) in FIG. 3). In addition, as shown in FIG. 3 (q), HE/'WE output from the system microcomputer 12
Since the signal is written, the reproduced video signal converted into a digital value by the A/D converter 8 is looked into the address specified by the address signals RAS and CAS of the field memory 9.

Next, in PLAY mode, the Bose key does not press 5TILL
We will explain the operation when transitioning to . Even if the Bose key is pressed while the head is scanning the field A2 track, the capstan motor continues to rotate, and after writing all the images of field A2 to the field memory 9, the field switching screen is activated. The capstan motor rotation command does not stop until the pulse wave of the ADHCLR signal rises, and at that point the RE/WE signal enters the read mode. Therefore, the data of field A2 written in field memory 9 is read out and D/
After being converted into an analog signal by the A converter 11, it is output as a video signal through the switch 14. Here ADH-C
The LR signal is synchronized with the standard 30Hz signal, and the continuity of the even and odd fields is such that the Hsynch number of one field is 126 when reading the memory.
3.282.

In this way, a stable still reproduced image can be obtained even in segment recording.

Next, when the Bose key is pressed again in the 5TILL mode, the mode shifts to the PLAY mode. When the Bose key is pressed, the capstan motor rotation command is turned on and the capstan motor starts rotating. Speed control of the capstor/motor is performed by an output signal from a frequency generator (hereinafter referred to as FG) attached to the capstor/motor, but phase control in playback mode is performed using a control signal recorded on the control track 16. Since it is used as a phase comparison signal, in the example shown in Figure 3, after the first ADR-CLR pulse wave is output after the Bose key is pressed, the capstan motor is activated as shown in Figure (f). The servo pulls in. Servo force detection signal is L
After switching from OW to High, the RE/WE enters the write mode at the rising edge of the first ADH/CLH pulse indicating the start of the next field, and the reproduced video signal becomes the video output through the switch 14 again, and The data is written to the field memory 9.

Here, while the RE/WE signal is in the read mode, the still image of field 2 is played back, the Bose key is pressed and the PLAY mode is switched off again, the phase control of the capstan motor is retracted, and the video is played back from the beginning of the field. Since signals are output, there is no disturbance when switching images.

Here, a phase control pull-in detection circuit for the capstan motor is shown in FIG. The phase control pull-in detection circuit is composed of monostable multivibrators (MM) 18 and 19 and a D flip-flop (D-FF) 20. FIG. 6 shows a timing chart for explaining the operation of the phase control pull-in detection circuit. FIG. 4(a) shows a phase reference signal which is input to the monostable multivibrator 18. The output of the monostable multivibrator 18 is shown in FIG. 3(b). When this signal is input again to the monostable multivibrator 19, the waveform shown in (0) in the figure is obtained. This signal is transferred to D-FF200Å
Use it as power. A phase comparison signal as shown in FIG. 3(B) is input to the C input of the D-FF 20. Here, the phase control pulls in means that the phase difference between the phase reference signal and the phase comparison signal becomes a predetermined value d, that is, D-FF2
If the phase comparison signal exists in the High section of the pulse wave of the C input of 0, it is considered that the phase control has pulled in. Therefore, the output of the D-FF 20 becomes a servo pull-in detection signal, and if the level is Low, it is determined that the servo has not pulled in, and if it is Htgh, it is determined that the servo has pulled in. child,
- In the second step, the control signal is used as the phase comparison signal.

Here, regarding the phase control of the cylinder motor, Fig. 6 and
The explanation will be based on the total amount shown in Fig. 7. The cylinder rotational position detection signal is input to the monostable multivibrator 21 and becomes the H-8W signal shown in Fig. , the phase is compared with the phase reference signal shown in FIG. 6 (a), and the phase is controlled so that the phase difference becomes β.Here, PL
In AY mode, signal A that resets the memory counter
The DH/CLR is outputted from the system microcomputer 12 using the frequency-divided cylinder H-8Wi. However, in the still mode, the ADH-CLR signal is output from the system microcomputer 12 using pseudo H-8W in order to change the number of HCynch for each field. The phase of the pseudo H-SW multiplied signal reference signal is delayed by the rising pulse β by the delay circuit 23, and the phase of the falling pulse is delayed by γ. Here, even in the still mode, the cylinder phase control is in a retracted state, so the cylinder motor rotates stably even when the still mode is shifted to the PLAY mode.

As explained above, in this embodiment, when transitioning from the 5TILL mode to the PLAY mode, the still image stored in the field memory is played back until the phase control of the capstan motor is pulled in and the field start is detected. By switching to the normal reproduction image only after detecting the start of the field, it is possible to prevent image distortion when changing from the 5TILL mode to the PLAY mode.

FIG. 8 shows a circuit block diagram of a second embodiment of the present invention. The circuit block diagram of FIG. 8 is different from the circuit block diagram of the first embodiment of the present invention shown in FIG. A rotation direction command (FWD/5
TOP/REWIND) Full output.

FIG. 9 shows a timing chart for explaining the operation of the second embodiment of the present invention. In the PLAY mode, the reproduced video signal is directly output as a video output through the switch 14 (FIG. 9(h)).

In addition, as shown in FIG. 9 (cr), the system microcomputer 12
Since the RE/WE signal output from
It is written to the address specified by AS-CAS, and one field of images is written one after another.

Next, when the pause key is pressed while the head is scanning the field A4, the mode shifts to 5TILL mode, but the capstan motor continues to rotate as it is, finishes writing all the images of field A4 to the field memory 9, and then moves to the 5TILL mode. The rotation command signal of the capstan motor changes from forward rotation (FWD) to stop (STOP) at the rising pulse of the ADR-CLR signal indicating the start of the field (field 5).
). Also, instead of the RE/WE signal being read out, the still reproduced image is then read out from the field memory 9 and becomes a video output through the switch 14, as described in the first embodiment of this invention.

As mentioned above, the rotation direction command of the capstor/motor stops when the head finishes scanning field 4 on the tape, but due to inertia it continues to rotate, albeit slightly, until the 1st and 9th outputs. ), the head stops at a position on the track of the field washing 5. At this time, the count value of the counter 26 becomes 0 due to the reset signal from the system microcomputer 12. Thereafter, a REWIND capstan motor rotation direction command is output from the system microcomputer 12, and the capstan motor starts rotating in the reverse direction, so that the tape becomes reverse running. Here counter 25
The up-counter operation is performed by the control pulse otffi L and the up/down (U/D) command signal output from the system microcomputer 12. In this case, phase control of the capstor/motor is not performed, and only speed control is performed to maintain the same speed as during PLAY. Each time the tape is reversed and a control pulse is input, the count value of the counter 26 increases, and when the count value of the counter 26 reaches 3, the capsta/motor rotation direction command output from the system microcomputer 12 stops. . Here, too, it continues to rotate, although slightly due to inertia, and stops at a position where the head is on the track of field black 2, as shown in FIG. 9(h). During this time, the RE/WE signal is in the read mode, and the data of field black 4 written in the field memory 9 is read out.

The Bose key is pressed again, and PLA changes from 5TILL mode.
When shifting to Y mode, the capstor/motor rotation direction command output from system mico A2 is forward rotation (FWD).
When the up/down (U/D) command signal is down, the counter 25 operates as a down counter.

Therefore, every time a control pulse is input, counter 2
The count value of 5 decreases. The speed and phase of the capstor/motor are controlled, and when the count value of the counter 25 is 1, the servo pull-in detection signal becomes High (the servo pull-in detection circuit is as explained in the first embodiment of the present invention). ). Next, when the control pulse is input, the count value of the counter 26 becomes 0, and in this state, from where the ADH-CLR signal indicating the start of the field is input, the reproduced video signal becomes the video output again through the switch 14, and the RE /W! The signal is in write mode. At this time, as shown in FIG. 9(i), KSTII,
When transitioning from L mode to PLAY mode, the output field starts from field black 4 of the still image, and then the normal playback image starts from field 5, so
No missing images when switching from still mode to PLAY mode.

In this example, the count value of the counter is set so that the tape moves backwards by two fields when the mode is shifted to still mode. All you have to do is set the return amount.

As explained above, in this embodiment, when transitioning from the ST I LL mode to the PLAY mode, the phase control of the capstan motor pulls in and normal reproduction starts from the field next to the still reproduction field.
There is no screen disturbance when transitioning from the L mode to the P LAY mode, and a continuous normal playback screen following the still playback field can be seen.

Effects of the Invention As described above, the present invention can provide a magnetic recording and reproducing device that realizes still playback compatible with segment recording and that does not disrupt the reproduced image when switching from still playback mode to synchronized playback mode.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing a first embodiment of the present invention;
FIG. 2 is a track pattern diagram for segment recording, FIG. 3 is a timing chart for explaining the operation of the first embodiment of the present invention, FIG. 4 is a circuit diagram of a servo pull-in detection circuit, and FIG. 5 is a diagram of a servo pull-in detection circuit. Figure 4 is a timing chart for explaining the operation of the servo pull-in detection circuit, Figures 6 and 7 are auxiliary diagrams for explaining the pseudo H-5W signal, and Figure 8 is a timing chart for explaining the operation of the servo pull-in detection circuit.
The figure shows a circuit block A showing a second embodiment of the invention. FIG. 9 is a timing chart, FIG. 1Q, and FIG. 11 are timing charts for explaining the operation of the second embodiment of the invention. FIGS. 12 and 13 are auxiliary diagrams for explaining a conventional example of still playback when one field is recorded in one rack, and FIGS. FIG. 6 is an auxiliary diagram for explaining a conventional example of performing reproduction. 1... Magnetic tape, 2... Video track, 3... Head trajectory, 4... Field memory, 6... Timing generator,
6...System microcomputer, 7...Control track, 8...A/D...
Converter, 9...Field memory, 1o...
...Timing generator, 11...D/
A converter, 12... System microcomputer, 13.
...Capstan motor servo retraction detection circuit, 1
4...Switch, 16...Magnetic tape, 16...Control track, 17...
...Video track, 18.19...Monostable multivibrator, 20...D free lag flop, 21...Monostable multivibrator, 22
...% frequency divider circuit -223 ...delay circuit, 24 ... cylinder motor control circuit, 26 ...
...Counter, 26...Capstan drive. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 4 Fig. 5 (e) Fig. 6 AM e O Fig. 8) and b S

Claims (2)

[Claims] (1) Two heads with different azimuth angles are attached to 180° opposing positions on a rotating drum, and track patterns by each head are formed alternately diagonally in the longitudinal direction of the tape on the running tape, and one field is formed in multiple numbers. In a magnetic recording/reproducing device that records data divided into tracks, an A/D converter converts a reproduced video signal output from a head into a digital value during reproduction, and stores the reproduced video signal converted into the digital value. a D/A converter for converting the video information data read from the storage means into an analog signal, a timing generator for controlling the address and writing/reading of the storage means, and a capstan motor. A capstan motor control pull-in detection circuit for detecting that the phase control of the capstan motor control pull-in detection circuit is input, and a capstan motor control pull-in detection signal which is an output of the capstan motor control pull-in detection circuit is input, and writing/reading of the storage means is performed. It has a system microcomputer for controlling, and during normal playback, the playback video signal converted into digital data by the A/D converter is written into the storage means, and the playback video signal is used as a video output, and during still playback, the playback video signal is written into the storage means. The video information data written in the D/D is read out under the control of the output signal of the timing generator.
After being converted into an analog signal by the A converter, it becomes a video output, and when transitioning from still playback to normal playback, after detecting that the capstan motor control has been pulled in by the capstan motor control pull-in detection signal. , a magnetic recording/playback device characterized by switching to normal playback. (2) A pulse signal output for each field, a counting means for counting the number of pulses, and a magnetic tape that continues to run until the counted value of the counting means reaches a predetermined value when switching from normal playback to still playback. When performing reverse playback and switching from still playback to normal playback, after detecting that the capstan motor control has been pulled in by the capstan motor control pull-in detection signal, the count value of the counting means reaches a predetermined value. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the magnetic recording and reproducing apparatus switches to normal reproduction after reaching a certain value.