JP2501191B2 - Playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a reproducing apparatus such as a video tape recorder.

<Outline of the Invention> The present invention relates to a reproducing apparatus for reproducing video and audio recorded on a magnetic tape, and more particularly to an apparatus for reproducing audio at a speed higher than a normal reproduction speed.

<Prior Art> In a reproducing apparatus such as a video tape recorder, when the recorded video signal is reproduced, the running speed of the magnetic tape is made higher than the normal reproduction speed, and the recorded image is viewed in a short time. There is a function.

At this time, if the tape speed is n times the normal speed, the audio signal reproduced at the same time as the video signal has a frequency n times that of the normal audio signal, and becomes n times faster than the normal audio, which is very difficult to hear. It was hard.

In order to solve this problem, the audio signal reproduced at a speed higher than the normal reproduction speed is written to the memory at a certain clock and read from the memory at a clock slower than the write clock to convert the frequency of the audio signal to a normal frequency. A method called variable speech control (hereinafter abbreviated as VSC) is disclosed in JP-B-55-126.
It has already been proposed in Japanese Patent Publication No. 46 and the like.

<Problems to be solved by the invention> However, when attempting to adopt such a method in a video tape recorder, the tape speed is about 10 times during normal video search, and VSC is not performed. Well, 1
It is 0 times faster, and it is still very difficult to hear.

<Purpose of the invention> In order to solve the above problems, VSC during video search
In addition, the tape speed is controlled so that the reproduced voice can be heard quickly so that it can be heard easily.

It is known from the actual measurement that the tape speed is about double speed, so it is desirable to control the tape speed to be lower than double speed. Since it must be fast to some extent, the optimum value is about 1.5 times speed.

<Means for Solving Problems> (1) Overall Configuration This reproducing apparatus functions as a video reproducing means, an audio reproducing means, a reproducing speed switching means, an audio signal reproducing time expanding means, and the time expanding means. It is constituted by a switching means for switching and outputting a voice signal which has not been processed and a voice signal on which the time expansion means has been operated, and the reproduction speed switching means switches the reproduction speed to a speed higher than the normal reproduction speed and lower than or equal to double speed (for example, 1.5 times speed). In this case, the audio signal on which the time extension means operates is switched and output by the switching means, thereby outputting a sound that is easy to hear during the video search.

(2) Structure of reproducing speed switching means Tape feeding means for running the magnetic tape, speed detecting means for detecting the tape running speed, and recording on the magnetic tape for phase control of the magnetic tape and the video reproducing means. In the magnetic recording / reproducing apparatus, the magnetic recording / reproducing apparatus is provided with: phase detecting means for detecting the generated control signal; and control means for transmitting a predetermined signal to the tape feeding means according to the detection signals from the speed detecting means and the phase detecting means. The control means is provided with a correction means for correcting the detection signal from the speed detection means and the detection signal from the phase detection means to a predetermined value.

(3) Structure of video reproducing means A rotary head having a double azimuth head provided on a diagonal line of a rotary drum, a switch means for selecting reproduction output by each head, and a drive means for driving the switch means in a predetermined order. And a switch control unit for controlling the recorded magnetic tape at a reproduction speed of 1.5 times the normal reproduction speed, and switching to one of the double azimuth heads during the vertical blanking period by the switch unit.

<Embodiment> FIG. 1 shows an embodiment of the present invention. In FIG.
First, the capstan servo circuit 1 is the control head 2
The capstan motor 4 is controlled by the control signal from the device and the speed signal from the capstan 3 to keep the tape 5 at a constant speed.

The rotary head 6 reproduces a video track of the magnetic tape 5, and the head switching circuit 7 switches and outputs the video track in a predetermined order. The video reproducing circuit 8 converts the video signal into a video signal and outputs the video signal. The audio head 9 reproduces the audio track of the tape 5 and is amplified by the audio amplifier 10. At the time of normal reproduction, since the voice changeover switch 11 is connected to the terminal a side, the output of the audio amplifier 10 is output as it is through the voice changeover switch 11.

When the video search mode is set, the 1.5x speed signal is output by switching the video search switch 12.

The capstan servo circuit 1 changes the operation of the tape 5 so that the speed of the tape 5 becomes 1.5 times that of normal reproduction by the 1.5 times speed signal. This will be described in detail later.

The head switching circuit 7 also changes its operation by the 1.5x speed signal. This will also be described in detail later.

Also, the voice changeover switch 11 receives the terminal b by the 1.5x speed signal.
Switch to the side. As a result, the audio signal output from the audio amplifier 10 is the audio signal produced by the reproduction time expansion means 13.

Next, the reproduction time expansion means 13 will be described. If the standard reproduction waveform of the audio amplifier 10 during normal reproduction is as shown in FIG. 2, the waveform of FIG.

14 is a constant cycle T of the oscillator circuit 15 with the waveform of FIG. 2 as input.
(This cycle is about 20ms, for example) Square wave output (Fig. 6)
This is a chopper circuit that chops the ratio of conduction to non-conduction by T ₁ / T ₂ . This oscillator circuit 15 is a capstan 3
The speed signal from is used to change the normal speed to the speed during V ₁ search.
When _{V 2, T 1: (T} 1 + T 2) = V 1: a circuit for generating a waveform having a V ₂ becomes relevant. The chopper circuit produces the input waveform of FIG. 3 as the output waveform of FIG. 4 by the gate operation according to the ratio of T ₁ / T ₂ by the output of the oscillation circuit 15. That is, the waveform shown in FIG. 4 is the waveform truncated in the period T ₂ of the waveform shown in FIG. 16
Is a sawtooth wave generating circuit including a waveform shaping circuit and an integrating circuit so as to generate a sawtooth wave output (FIG. 7) which is operated by the output of the oscillation circuit 15 and has a period of T and which is excellent in linearity. Reference numeral 17 denotes a voltage frequency conversion circuit having a linear voltage frequency characteristic which produces a clock pulse (FIG. 8) whose frequency is converted by the output of the sawtooth wave generation circuit 16 so as to reduce the successive oscillation frequency. 18
Is an analog shift register for sequentially transmitting a voltage equal to the input voltage. The output waveform of the chopper circuit 14 (Fig. 4) is introduced as the input voltage, and the clock pulse of the voltage frequency conversion circuit 17 (Fig. 8) is controlled by the control circuit. Each time it enters 19, the input voltage is sequentially transmitted to the output terminal. This analog shift register 18 is also called a bucket relay
This IC can be configured as an IC, and by connecting the combination of FET and capacitor in cascade and controlling the FET with a clock pulse, the input voltage accumulated in the capacitor of the previous stage is sequentially transmitted to the capacitor of the subsequent stage. This transmission time is determined by the frequency or width of the clock pulse. In the figure, the transmission time is longer as it approaches the end of one cycle. Therefore, within one cycle T of the output of the voltage frequency conversion circuit 17, the output waveform of FIG.
The waveform A'B 'in the T ₁ period is expanded to A "B" according to the frequency of the clock pulse. Therefore, the shift register 18
As shown in FIG. 5, a standard speed recording waveform, that is, a waveform expanded to a fundamental frequency that matches the standard speed reproduction waveform (FIG. 2) is obtained at the output of FIG. This expanded waveform has a wave number of 1 / 1.5 per unit time with respect to the original sound shown in FIG. 20 is a shift register
It is a waveform shaping circuit for shaping noise-free waveforms by removing noises on the output waveforms of 18. This waveform shaping circuit 20
The output of is connected as the input of the main amplifier of the video tape recorder, and the playback sound can be heard from the speaker.

According to the present invention configured as described above, the high-speed reproduction waveform appearing at the input of the chopper circuit due to the pulse of the oscillation circuit is truncated at a predetermined time, and is a clock pulse generated within a period synchronized with this oscillation frequency. By expanding the waveform remaining in the truncated time, it is possible to restore the waveform of the frequency matching the standard speed reproduction waveform. For this reason, this restored waveform is reduced in the number of waves per unit time when viewed from the recorded contents, that is, the sound, and can be heard by the human ear as a state of speaking quickly. In this case, since the frequency is the same as that at the standard reproduction speed, the intelligibility does not decrease, and the recorded content can be sufficiently grasped in a time sufficiently shorter than the recording time.

Next, the tape speed switching means will be described. Figure 9 shows the first
The capstan servo circuit 1 in the figure and its surroundings are more concrete.

In the speed controller, the signal amplified by the amplifier 21 is input to the frequency divider 22. This frequency divider 22 outputs the signal from the amplifier 21 as it is at the time of normal reproduction, but when a 1.5 × speed signal is input to this frequency divider 22, the frequency of the input signal is doubled and then divided into 3 minutes. Output after lap. The output signal of the frequency divider 22 is input to one input terminal of the summing amplifier 24 via the frequency discriminator 23. Frequency discriminator
In 23, the frequency of the input signal is determined, and the frequency divider
If the signal is not divided at 21, the input signal is output as it is. If it is divided, the capstan motor 4 is set to 1.5.
A predetermined signal for double speed is output.

In the phase controller, the output signal of the amplifier 25 is the frequency divider 26
Is input to This frequency divider 26 outputs the signal from the amplifier 25 as it is during normal reproduction.
When a 1.5 × speed signal is input to the control head 2, the control signal, which is track information obtained from the control head 2, is divided into three to maintain the positional relationship between the reproducing head and the recording track pattern on the magnetic tape 5. Divider 26
Is output to the other one input terminal of the summing amplifier 24 via the phase comparator 27.

In the above-mentioned control block diagram, in the case of normal reproduction, the blocks 22 and 26 and the frequency discriminator 23 output the input signal as they are, as described above, so that the speed of the tape 5 is controlled to the normal speed.

 Next, the operation at the time of reproduction at 1.5 times speed will be described.

When the 1.5x speed signal is input to the frequency divider 22 and the frequency divider 26, the frequency corresponding to the rotation speed from the frequency generator FC is converted into 2/3 by the frequency divider 22 and this reduced signal is used. Since the frequency is input to the addition amplifier 24, the addition amplifier 24 outputs a drive signal for multiplying the rotation speed of the capstan motor 4 by 3/2 (= 1.5). In this way, the speed control section feeds the magnetic tape 5 at 1.5 times the normal reproduction speed.

In the phase controller, the control signal divided by 3 is input to the phase comparator 27, so that the phase relationship between the reproducing head and the recording track pattern on the magnetic tape 5 is maintained at 1.5 times speed. As a result, the phase relationship between the recording track pattern on the magnetic tape 5 and the locus pattern of the reproducing head is maintained even if the reproducing speed of the magnetic tape 5 is increased by 1.5 times, and noiseless reproduction at 1.5 times speed is possible.

As described above, since the running speed of the magnetic tape is controlled at the time of reproducing at 1.5 times speed, the positional relationship between the recording track pattern on the magnetic tape and the locus of the reproducing head, that is, the phase control is also performed. Noiseless reproduction is possible even during reproduction.

 Next, the head switching circuit will be described.

In the present invention, a double azimuth head is adopted as a plurality of reproducing heads. An embodiment will be described below with reference to the drawings.

FIG. 10 shows a rotary head 6 used in one embodiment of the present invention. Another reproducing head L'is provided in the vicinity of one reproducing head R via a predetermined gap G. The reproducing head L'has a different azimuth from the reproducing head R and has the same azimuth as the reproducing head L on the diagonal line.
If the horizontal synchronizing signal is H, the size of the gap G between the reproducing heads R and L'is 1H or 2H. This configuration is called a double azimuth head.

The magnetic tape recorded by the reproducing head 6
The positional relationship between the magnetic tape and the reproducing head when reproduced at 1.5 times speed is shown in FIG. 11, where TL ′, TL and TR are reproducing head loci on the magnetic tape 5 by the reproducing heads L ′, L and R, respectively. Is. When reproducing the first frame, the reproducing head L'is used instead of the reproducing head R for reproduction. As a result, when reproducing the first field, the reproducing head TL ′ reproduces the recording track L1 having the same azimuth, and the azimuth and the azimuth angle of the reproducing head L ′ during recording between the adjacent recording tracks R1 and R2 are different. Not played.

As described above, in the video tape recorder in which the running of the rotary head 6 and the magnetic tape 5 is phase-controlled, the recording track pattern and the locus of the reproducing head at the time of 1.5 times speed reproduction are 4 fields as shown in FIG. Since there is a relationship in which the reproducing head is one cycle, the reproducing head also has a pattern in which four fields are one cycle and the reproducing head is TL'-TL-
You can switch to TR-TL ... Further, the positional relationship between the reproducing head and the recording track pattern, that is, the tracking information is obtained by the control signal recorded on the magnetic tape 5 at the normal reproducing speed, but at the time of reproducing at 1.5 times speed, the control signal is divided by 3 to perform tracking. You can control it.

FIG. 12 shows a control block diagram for performing the above control.

R, L ′, L in the figure are the reproducing heads already described, and 31, 32, 3
Reference numeral 3 is a head amplifier for the reproducing head. S
W1 is a control switch for selecting the output signal of the head amplifier 31 or 32, and SW2 is a control switch for selecting the signal from the switch SW1 or the output signal of the head amplifier 33. The signal selected by the switches SW1 and SW2 is output as a predetermined video signal via the demodulation circuit 34.

On the other hand, in the video tape recorder, the rotary head 6
The head switch pulse for switching the reproducing head is created in accordance with the rotation of the reproducing head, which is conventionally used for switching the reproducing head RL in the rotating head 6 by this pulse. , It is used as a control signal of the control switch SW2 for switching either one of the reproducing heads L or R, L '.
Also, this head switch pulse is an exclusive OR of 2 input terminals.
It is input to one input terminal of the circuit 35, and is input to the other one input terminal through an integrating circuit including a resistor 36 and a capacitor 37. As a result, a pulse is output from the exclusive OR circuit 35 at both the rising and falling edges of the head switch pulse, and this pulse is output from each of the four-stage D-type flip-flop (F / F) circuits FF1 to FF4. Input to clock pin CK. Further, a signal obtained by dividing the control signal obtained during reproduction by 3 is passed through a differentiating circuit composed of a capacitor 38 and a resistor 39 to set terminal S of flip-flop circuit FF1.
And the reset terminals R of the flip-flop circuits FF2 to FF4. As a result, the flip-flop circuit FF1 is set at the rising edge of the control signal,
The flip-flop circuits FF2 to FF4 are reset. Reference numeral 40 denotes a pulse selection circuit, to which the 1.5 × speed reproduction signal, the head switch pulse, and the signal at the output terminal Q of each flip-flop circuit FF1 to FF4 are input.
From 40, a head selection pulse for controlling the control switch SW1 and a chroma rotation signal for controlling the demodulation circuit 34 are output.

Next, the control operation at the time of reproducing at 1.5 times speed will be described with reference to the time chart of FIG.

According to the signals at the output terminals Q of the flip-flop circuits FF1 to FF4, the pulse selection circuit 40 outputs the head selection pulse and the chroma rotation signal used for the black macrostalk removal processing by the low frequency conversion color signal demodulation circuit.
When a 1.5 × speed reproduction signal is input, these signals are output in a predetermined order so that the output signal for video reproduction becomes maximum.

Now, in the period of the first field, the flip-flop circuit FF1 is set and outputs "H" when the pulse of the control signal divided by 3 rises, and the flip-flop circuits FF2 to FF4 are reset and outputs "L". To do. Next, in the second field, when the head switch pulse falls, the pulse is input to the terminal CK of each flip-flop circuit FF1 to FF4 as a clock signal, so FF2 of the flip-flop circuit outputs "H" and FF1 , FF3 and FF4 output "L". In this way, the flip-flop circuit that outputs “H” according to the clock signals at both edges of the head switch pulse sequentially circulates in the order of FF1 → FF2 → FF3 → FF4 → FF1 →. As a result, a pulse having one cycle in four fields is obtained, and the pulse selection circuit 40 sets the head selection pulse to "H" only in the first field, and the switch
SW1 is switched to the b side, the signal from the reproducing head L'is selected, and the head selection pulse becomes "L" in the second to fourth fields, and the switch SW1 is turned on to the a side for reproduction. The signal from the head R is selected. The switch SW2 is controlled according to the head switch pulse,
When it is "H", the switch SW2 selects the signal from the c side, that is, the signal from the switch SW1, and when it is "L", the signal from the d side, that is, the reproduction head L is selected. This allows for example
As shown in FIG. 11, the reproducing heads of L'in the first field, L in the second field, R in the third field and L in the fourth field are selected.
The cycle repeats.

In this way, a noiseless 1.5x video reproduction signal can be obtained. Further, by supplying the chroma rotation signal to the demodulation circuit 34, normal color reproduction can be performed. Further, since switching of the reproducing head is performed during the vertical blanking period, skew noise due to switching of the reproducing head does not appear on the reproducing screen.

During normal reproduction, the head selection pulse is "L", and at this time the switch SW1 is switched to the side a, the reproduction head R is selected, and the switch SW2
When the head switch pulse is "H", the signal from the c side, that is, the reproducing head R is selected, and when the head switch pulse is "L", the signal from the d side, that is, the reproducing head L is selected. Further, the head switch pulse input to the pulse selection circuit 40 is used as it is as a chroma rotation signal.

The above is the normal head L and double azimuth heads R and L '
In the above description, the so-called double azimuth 3 head was used. However, if a guard band is generated in the recording track pattern during 1.5x speed reproduction, a double azimuth 4 head using 2 double azimuth heads will be used.
Double speed noiseless playback is possible.

As described above, one of the two normal rotary heads is a double azimuth head, and
During double-speed reproduction, one of the double azimuth heads, which is different from the azimuth angle during normal reproduction, is used during reproduction of a predetermined frame, so that noise due to reproduction of adjacent tracks can be eliminated.

<Effects of the Invention> As described above, the present invention can output the audio in a videotape recorder or the like so that the audio can be easily heard when performing a video search while listening to the audio. Moreover, the reproduction speed is set to a constant high speed of 1.5 times the normal reproduction speed, and when reproducing a predetermined frame, one of the double azimuth heads different from the azimuth angle during normal reproduction is used for reproduction. Therefore, the noise due to the reproduction of the adjacent track can be eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIGS. 2 to 8 are waveform diagrams for explaining the operation of the same embodiment, and FIG. 9 is a block diagram of another embodiment of the present invention. FIG. 10 is a plan view of a rotary head used in the other embodiment, and FIG. 11 is a view showing a head locus on a magnetic tape by the rotary head shown in FIG.
FIG. 12 is a control block diagram for controlling the rotary head in FIG. 10, and FIG. 13 is a time chart for explaining the operation of the control block diagram shown in FIG. 1 ... Capstan servo circuit, 2 ... Control head, 3 ... Capstan, 4 ... Capstan motor, 5 ...
Magnetic tape, 6 ... Rotating head, 7 ... Head switching circuit, 8 ... Video reproduction circuit, 11 ... Audio changeover switch, 13 ...
Reproduction time extension means.

Claims (1)

(57) [Claims] 1. A video reproducing means for reproducing the video information recorded on the magnetic tape, an audio reproducing means for reproducing the audio information recorded on the magnetic tape, and a reproducing speed of the video information and the audio information at a normal speed. Playback speed switching means for switching to a constant high speed of 1.5 times the playback speed, time extension means for cutting off a part of the audio signal and extending the playback time, and not passing through the time extension means at the normal playback speed. A reproducing device comprising a switching means for switching and outputting an audio signal and the time-expanded audio signal passed through the time expansion means during the constant high-speed reproduction, wherein the video reproduction means is on a diagonal line of a rotary drum. A rotary head having a double azimuth as a head, switch means for selecting reproduction output by each head, and the switch means in a predetermined order. And a switch control unit for driving the recorded magnetic tape, wherein the recorded magnetic tape is switched to one of the double azimuth heads during the vertical blanking period by the switch unit during the constant high-speed reproduction. .