JPS59186482A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To perform normal reproduction and frame-by-frame reproduction stably without requring any complex circuit by arranging the 3rd head which has the same characteristics that a CH2 head for even field parts adjacently to a CH1 head for odd field parts in addition to two video heads which are used for the normal reproduction. CONSTITUTION:A video head 4 for CH2-side reproduction and a video head 30 are used for still picture reproduction and trace a reproduction position C and a reproduction position D. In this case, those two video heads reproduce only the signals of a CH2 part, but a still picture which is clearer than before is obtained. When the tape is fed, frame by frame, a control signal 15 detected after a capstan motor 5 is driven is delayed by a multivibrator 18, and the motor is stopped the delay time later. The delay time of the multivibrator 18 is adjusted by a resistance 21, etc., to trace the reproduction positions C and D by the video heads even during continuous frame-by-frame reproduction, thereby reproducing a clear still picture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic recording and reproducing apparatus capable of continuously or temporarily reproducing still images frame by frame.

[Prior art]

In a video tape recorder (hereinafter referred to as a VTR), in order to reproduce a magnetic tape, which is a recording medium, a rotating video head rotated by a motor must trace a predetermined recorded portion of the tape. To do this, a control pulse signal for position detection (hereinafter referred to as a control signal) recorded on the same tape is reproduced, and the tracing position of the rotating video head is determined from that position.

Fig. 1 shows its schematic diagram. 1 is a magnetic recording tape, 2 is a drum motor, 3 and 4 are video heads, 5 is a capstan motor for tape feeding, 6 is a control signal detection head, 7 is a video head position detection head, 8 is a waveform shaping circuit 9 is an amplifier, 10 is a waveform shaping circuit, 11 is a phase comparator, 12 is a drum motor drive circuit, 13 is a capstan motor drive circuit, the signal shown in FIG. 2 (1), and 15 is a waveform shaped control signal. , FIG. 2 (Signal 14 shown in 2 is a video head switching signal. Video heads 3 and 4 are dedicated for recording and reproducing the odd field part (hereinafter referred to as CH1 part) and the even number field part (hereinafter referred to as CH2 part), respectively. The two heads record and playback alternately.The video head switching signal shown in FIG. 2 (2) controls the operation switching of these two video heads.Recorded To play a magnetic tape, a control signal detected from the tape and video heads 3 and 4 are used.
Adjust the phase relationship and move the specified part to the video head 6.4.
must be controlled so that it is traced. A signal indicating the position of the video heads 3 and 4 is obtained as a head switching signal 14 by shaping the signal detected by the head 7 in a waveform shaping circuit 8. Therefore, by determining the phase relationship between the head switching signal 14 and the control signal 150, the video head 6.4 can trace a predetermined position on the tape and a clear reproduced image can be obtained. The phase comparator 11 receives the head switching signal 14 and the control signal 150.
The phases are compared and the capstan motor 5 and drum motor 2 are controlled so that they are in a predetermined phase.

Figure 2 +i+, [21 shows general control signal 1]
5 and head switching key number 140 are shown. During the 'L' period of the head switching signal 14, the CH1 video head is
During the H' period, the CH2 video head traces a portion of the tape recorded by the same type of head.

The video head 6.4 has CHl, CI(2
Even if you trace a part that was recorded with a head of a different format, it cannot be played back. As shown in Figure 3, two images recorded by the CH1 and CH2 heads are arranged alternately on the tape, and a control signal is detected.
By matching the phase with the head switching signal 14, the video head 6.4 can trace each portion, and a clear reproduced image can be obtained. Now, let us consider the case where this magnetic recording/reproducing device stops the capstan motor and reproduces a still image. The video head 6.4 will trace the same part on the tape, but in order to minimize the noise and make the screen easy to see,
The trace position indicated by must be reproduced. If C
If you trace only the Hl and CH2 parts, the reproduced signal of 6°4 to the video will be completely noise-like on one side and S
This is because Ha falls. Trace positions such as those shown by A and B in FIG. 6 are convenient because signals can be picked up from CH1 and CH2, respectively. Now consider the case where frame-by-frame advance is performed and the playback position ρ) is also moved to the playback position B.

When the capstan motor 5 is driven to move the tape, the playback control signal is detected at t1 when the motor starts up or at t2 just before the stop position, as shown in Figure 4, and the playback control signal determines the stop position. Adjustments cannot be made and frame-by-frame forwarding operations are not possible. Figure 4 (1
) shows the rotational speed of the capstan motor 50, and FIG. 4 (2) shows the reproduction control signal. FIG. 5 shows an example in which the position of the control head B is slightly shifted from that shown in FIG.

Components having the same functions as those in FIG. 1 are designated without the same number. 16 indicates the position of the control head B in FIG.

17 is a delay circuit, 18 is a mono multivibrator, 19
is the capstan motor start/stop control circuit,
20 is a signal changeover switch, 21 is a variable resistor, 22 is a capacitor, 26 is a signal delayed by the multivibrator 18, and 24 is a start signal input terminal for starting the capstan motor.

Consider a case where frame-by-frame forwarding is performed to move from still image playback position A to playback position B in FIG. During still frame-advance playback, the switch 20 is on the contact a side, and when a start signal is supplied to the terminal 24, the control circuit 19 rotates the capstan motor 5 to feed the tape. Since the head 6 for detecting the control signal is moved closer to the video head than in the case of FIG. 1, the control signal can be detected in the middle between the start and stop of tape feeding, as shown in FIG. Figure 6 (1) is the start signal of the capstan motor, Figure 6 (2) is the rotational speed of the capstan motor, Figure 6 (3) is the student control signal, and Figure 6 (4) is the output signal of the multivibrator 18. This is an output signal.This reproduction control signal is delayed by the multivibrator 18 and stops the capstan motor 5.Multivibrator 1
By adjusting the delay amount of 8, accurate frame advance can be performed. Next, consider the case of normal playback.

For normal playback, the control head must be in the position of the control head 6 shown in FIG. Further, the phases of the control signal and head switching signal must have the phase relationship shown in FIG. However, in FIG. 5, since the position of the control head O is shifted to perform frame-by-frame playback (position 16 is normal), a clear playback image cannot be obtained as it is.

Therefore, the control signal 15 is input to the delay circuit 17 and delayed for a certain period of time, and as shown in FIG. When obtaining a reproduced image, since the delay circuit 17 is included in the phase comparison control system between the video head 6.4 and the control signal, there is a drawback that motor control tends to be unstable compared to conventional methods, and this is compensated for. Therefore, many considerations such as phase compensation had to be taken, and the circuit became complicated.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic = a recording/reproducing device which eliminates the above-mentioned drawbacks of the prior art and is capable of stably performing normal playback and frame-by-frame playback without using complicated circuits.

[Summary of the invention]

In addition to the two video heads used for normal playback, the present invention uses a third head having the same characteristics as the CH2 side head.
By placing it adjacent to the H1 head, it is possible to perform both normal playback and frame-by-frame playback while maintaining the conventional control head position.

[Embodiments of the invention]

An embodiment according to the present invention is shown in FIGS. 8 and 9, and FIG.
An explanatory diagram of the operation is shown in FIG. In FIGS. 8, 9, 10, and 11, FIG.

Components having the same functions as those in FIGS. 2, 3, 4, 5, 6, and 7 are given the same numbers.

In FIG. 8, 26 is a rotating drum on which a video head is fixed, and 50 is a video head added according to the present invention, which has the same characteristics as the video head 4 of CH2. In still image reproduction, the video head 4 and video head 60 are used for reproduction, and in normal operation reproduction, the video head 6 and video head 4 are used for reproduction.

The control head 6 shown in FIG. 9 is in the same position as in FIG. 1, and in the normal playback mode, the switch 20 is on the b side, so the configuration as explained in FIGS. 1 and 2, The signal timing is correct and a clear reproduced image can be obtained.

Next, the case of playing still images will be explained.

For still image reproduction, the video head 4 and video head 30 for reproduction on the CH2 side are used. Therefore, in order to obtain a still image with less noise, the playback position C and the playback position shown in FIG.
o is the time to trace. In this case, the two video heads reproduce only the signal of the CH2 portion, but they can reproduce more signal portions than the patterns shown in FIG. You can get still images.

Next, consider frame-by-frame feeding from playback position C to playback position. The switch 20 is on the a side. Input terminal 24
The start signal supplied to the capstan motor 5
The fact that the control head can be detected during the period from when it starts, rotates, and reaches the desired stop position is the 10th point.
This can be understood from FIG. FIG. 11(1) shows the rotation speed of the capstan motor, FIG. 11(2) shows the control signal, and FIG. 11(3) shows the output of the multivibrator. That is, the control signal 15 detected after driving the capstan motor 5 is delayed by the multivibrator 18, and the capstan motor 5 is stopped after the delay time. By adjusting and selecting the delay time of the multivibrator 18 with the resistor 21, etc., the video head can be moved to playback positions C and D in Fig. 10 even when performing continuous frame-by-frame playback.
The position of the camera can be traced and clear still images can be played back.

As described above, by placing one third video head with CH2 side characteristics adjacent to the CH1% head and using the CH2 side characteristic head for still image reproduction, Even in VTRs that can perform frame-by-frame playback, the control signal detection head can be placed in the same position as before.
The motor control characteristics during normal playback may be the same as conventional ones, and there is an advantage that a complicated compensation circuit is not required.

〔Effect of the invention〕

As described above, according to the present invention, in a VTR that can feed still images one frame at a time or continuously, frames of a still image can be moved without changing the position of the control signal detection head from that of a normal playback-only VTR. The feed operation can be performed accurately, and the motor control characteristics are the same as those of normal playback-only VTRs, and the playback control signal can be delayed to change the apparent position of the control signal detection head to the normal playback-only VTR. It has the advantage that it only takes 7 hours to match with the VTR.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of a VTR, and FIG. 2 is an explanatory diagram showing the configuration of a VTR.
Figures 3 and 4 are explanatory diagrams of the signal phases in the figure, and Figures 5 and 4 are tape button diagrams and operational diagrams for still images and frame-by-frame forwarding.
Figures 6 and 7 & Figures 6 and 7 show still images and frame-by-frame playback of a conventional example of configuration and operation explanations, and Figures 8 and 9 are still images and frame-by-frame playback according to the present invention. The configuration diagrams of the VTR, FIGS. 10 and 11, are explanatory diagrams of the operation of FIG. 9. DESCRIPTION OF SYMBOLS 1... Magnetic tape, 34... Video head, 5... Capstan motor, 6... Control head, 11... Phase comparator, 18... Mono multi-pipe rake, 19... Start/stop control circuit, 30... Video head dedicated to still images. False 1 Figure 2 Literary 3 Figure CHICH2CHI CH2CHI Figure 4 (2), ” Figure 5 Figure 6 Figure 7 Figure 7 and Figure negative force F Figure /θ Figure // Figure

Claims (1)

[Claims] In a magnetic recording and reproducing device that has the function of continuously reproducing still images one frame at a time from a magnetic tape,
It has a first video head that exclusively records and reproduces the odd field part of a standard television signal, and a second video head that exclusively records and reproduces the even field part, and has the same characteristics as the second video head. A sixth video head is arranged adjacent to the first video head, the first and second video heads are used during normal recording and playback, and the second and third video heads are used during still image playback, The position of the control note detection head that reproduces the control signal is
A magnetic recording and reproducing device characterized in that the position is the same as that of a magnetic recording and reproducing device exclusively for normal recording.