JPH0744672B2 - Video tape recorder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a helical scan type video tape recorder, and more particularly to a recorded magnetic tape title,
The present invention relates to a video tape recorder in which image information such as date and recording time is recorded, and the image information such as the title can be superimposed on the reproduction screen during reproduction.

[Background of the Invention]

In recent years, small and lightweight portable video tape recorders have become popular as home video tape recorders, and it has become possible to connect a video camera to the portable video tape recorder and produce a desired program. In this way, when program production is possible, the character information such as the title and date of each program on the recorded magnetic tape can be recorded further, and the title and characters can be displayed at the beginning of each program during playback. It is necessary to

As described above, as a method of recording desired image information on a recorded magnetic tape, for example, as disclosed in JP-A-57-79783, a rotary head for erasing is preceded by a recording head. There is known a method in which a portion of the recorded magnetic tape where the image information is to be inserted is erased, and a desired image signal is recorded on the erased portion with a recording head.

However, according to this method, a part of the screen of the program already recorded on the magnetic tape is completely lost, and it is impossible to reproduce the part later. In particular, inserting the title is the first part of the show, and
When a general user produces a program, since the image pickup is started after a scene of interest occurs, the first part of the program has many important screens. Therefore, if the title is inserted in this portion, an important screen will be lost, and the interest of the program may be lost.

[Object of the Invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to superimpose new image information such as a title on the image information without damaging the video image recorded on the magnetic tape. (EN) Provided is a video tape recorder capable of arbitrarily correcting the superimposed image.

[Outline of Invention]

To this end, the present invention provides a recording area for a time-axis-compressed and coded digital signal on an extension of a track on which a video signal representing a video image on a magnetic tape is recorded, and in this area. It is characterized in that image information such as a title can be recorded, and when the video signal is reproduced, the image information can be reproduced as needed and superimposed on the video signal.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a video tape recorder according to the present invention, in which 1 to 4 are input terminals, 5 is a luminance signal recording processing circuit, 6 is a chroma signal recording processing circuit, and 7 is a chroma signal recording processing circuit.
Is an FM voice recording processing circuit, 8 is a pilot signal generation circuit,
9, 10 is an adder circuit, 11 is a switching signal generator, 12 and 13 are switches, 14 and 15 are amplifiers, 16 and 17 are switches, 18 and 19 are rotary heads, 20 is magnetic tape, 21 is a rotary cylinder, 22 Is an adder circuit, 23 and 24 are switches, 25 and 26 are low pass filters, and 27 and 2
8 is a noise suppression circuit, 29 is a sample hold circuit, 30 is an analog-digital converter, 31 is a PCM encoder, 32
Is a discrimination signal generator, 33 is an addition circuit, 34 is a system controller, 35 is a character data control circuit, 36 is a character data generation circuit, 37 is a FSK (Frequency Shift Keying) circuit, and 38,3.
8 ', 39 are mode signal input terminals, 40, 41 are amplifiers, 42, 43 are switches, 44 is ATF (Automatic Trach Finding) control circuit, 45 is capstan motor, 46 is FM sound reproduction processing circuit, 47 is brightness A signal reproduction processing circuit, 48 a chroma signal reproduction processing circuit, 49 an addition circuit, 50 a waveform equalization circuit, 51 a data strobe circuit, 52 a PCM decoder, 53 a digital-
An analog converter, 54 is a sample hold circuit, 55 and 56 are low pass filters, 57 and 58 are noise suppression circuits, 59 is an error amount identification circuit, 60 is a discrimination signal detection circuit, 61 is a character data output operation determination circuit, 62 and 63 are switches, 64 and 65 are output terminals, 66 is a sync separation circuit, 67 is an addition circuit, 68 and 69 are output terminals, 70 is an FSK decoder, 71 is an inverter, 72 is an error display circuit, and 73 is character data. The generation circuit, 74 is a character data control circuit.

In this embodiment, the ATF control method is adopted as the servo control method, the audio signal is FM-modulated (frequency-modulated) as the audio-signal recording method, and the video signal and the frequency-multiplexed signal (for example, FM-modulated luminance signal A method of recording by multiplexing between the band and the band of the low-frequency converted chroma signal (hereinafter, FM)
Audio recording method) and a method that PCM-modulates the audio signal, further performs time-axis compression and modulation suitable for recording, and then records on the extension line of the track where the video signal is recorded (hereinafter referred to as overlap PCM recording). Method) is adopted, and these will be explained first.

In FIG. 1, at the time of recording, as shown in FIG. 4, the mode setting signals 4A, 4B, 4E supplied from the input terminals 38, 38 ', 39 to the system controller 34 are all "L" (low). Level), and switches 16 and 17 are both closed to the REC side.
In addition, the control signal output from the system controller 34
4E is also "L", the switches 23 and 24 are closed to the side a, and the character data control circuit 35 is set to the inactive state.

The video signal is input from the input terminal 1, and the first audio signal accompanying the video signal is input from the input terminal 2. The video signal is supplied to the luminance signal recording processing circuit 5, and the luminance signal is separated and subjected to processing such as FM modulation. The FM-modulated luminance signal (hereinafter referred to as FM luminance signal) is added by the addition circuit 10
Is supplied to. The video signal is also supplied to the chroma signal recording processing circuit 6 to separate the chroma signal and perform processing such as low frequency conversion. This low-frequency converted chroma signal (hereinafter referred to as low-frequency converted chroma signal) is added by the adder circuit 9.
Is supplied to. The first audio signal from the input terminal 2 is subjected to processing such as FM modulation in the FM audio recording processing circuit 7, and the FM-modulated audio signal (hereinafter referred to as FM audio signal) is supplied to the adding circuit 9. The addition circuit 9 is also supplied with a pilot signal generated by the pilot signal generation circuit 8.

The addition output of the low-frequency conversion chroma signal, the FM voice signal, and the pilot signal of the adder circuit 9 is supplied to the adder circuit 10, and the FM luminance signal is added. The synthesized signal output from the adder circuit 10 has the FM voice signal multiplexed between the band of the FM luminance signal on the high frequency side and the band of the low frequency conversion chroma signal on the low frequency side, and the frequency band of the low frequency conversion chroma signal. The pilot signal is multiplexed on the lower side,
It is supplied to the amplifiers 14 and 15 via the switches 12 and 13 which are closed to the a side. The combined signals amplified by the amplifiers 14 and 15 are supplied to the rotary heads 18 and 19 on the rotary cylinder 21 that rotates in the arrow direction via the switches 16 and 17 closed to the REC side by the system controllers 16 and 17, respectively. To be done.

The magnetic tape 20 is spirally wound around the outer circumference of the rotary cylinder 21 at an angle sufficiently larger than 180 °, and runs.
The rotary heads 18 and 19 alternately scan the magnetic tape 20, although there is a period in which the magnetic tape 20 is partially scanned at the same time. The switches 12 and 13 are controlled by a switching signal 4C phase-synchronized with the rotation of the rotary cylinder 21 from the switching signal generator 11. By this control, the period from when the rotary head 18 starts scanning the magnetic tape 20 (at this time, the rotary head 19 also scans the magnetic tape 20) until the rotary head 19 leaves the magnetic tape 20 (this period overlaps As shown in FIG. 4, the switching signal 4C becomes "H" (high level), the switch 12 is closed to the b side, and is closed to the a side other than this overlap period. The switch 13 is similar, and the rotary head 19 starts scanning the magnetic tape 20 (at this time, the rotary head 18
Is also scanning the magnetic tape 20) and then the rotary head 18
The switching signal 4C becomes "H" during the period until the magnetic tape 20 is separated from the magnetic tape 20 (this period is also the overramp period).
Close to the side and close to the side a for the other period.

Therefore, the rotary heads 18 and 19 are added to the adder circuit 10 during the scanning period of the magnetic tape 20 excluding the overlap period.
Composite signal from (hereinafter referred to as the first composite signal)
Is recorded on the magnetic tape 20. During this period the rotary head 18,1
This is the period during which 9 turns 180 °,
Reference numerals 18 and 19 alternately record the first combined signal from the adder circuit 10 on the magnetic tape 20.

As described above, the first audio signal from the input terminal 2
It is recorded by the FM voice recording system.

On the other hand, the second audio signal is supplied from the input terminals 3 and 4. The second audio signal is a monaural signal, a stereo signal, or a multiplexed signal, and the audio signal supplied from the input terminal 3 is the main signal and the audio signal supplied from the input terminal 4 is the sub signal.

These main and sub signals are supplied to low-pass filters (hereinafter referred to as LPFs) 25 and 26 via switches 23 and 24, respectively, band-limited, and noise suppression circuits (hereinafter referred to as NR circuits) 2
After the dynamic range is compressed to 1/2 by 7,28, it is synthesized by a sample and hold circuit (hereinafter referred to as S / H circuit) 29 that alternately samples and holds the main signal and the sub signal, and the analog-digital converter (Hereafter referred to as A / D converter) 3
Digitized at 0. This digitized audio signal is supplied to the PCM encoder 31, and an error correction signal such as a parity signal for error correction and the second audio signal supplied from the discrimination signal generator 32 are monaural signals, stereo signals, or A discrimination signal (ID signal) indicating whether the signal is a multiplex signal or the like is added, the time axis is compressed, and further, it is modulated to be suitable for recording. The output signal of the PCM encoder 31 (hereinafter referred to as time-axis compressed PCM audio signal) is added to the pilot signal from the pilot signal generation circuit 8 in the addition circuit 33, while the addition signal is passed through the switch 12 and the amplifier 14
Is supplied to the rotary head 18 via the switch 16, and then is amplified by the amplifier 15 via the switch 13 and then supplied to the rotary head 19 via the switch 17.

Here, the PCM encoder 31 is switched when the rotary head 18 is in the overlap period and the switch 12 is closed to the side b and when the rotary head 19 is in the overlap period.
When 13 is closed on the b side, the time axis compressed PCM audio signals are output respectively. Therefore, the rotary heads 18 and 19 alternately record the second composite signal of the time-axis compressed PCM audio signal and the pilot signal on the magnetic tape 20 every overlap period.

The recording method of the second audio signal is the overlap PCM recording method, and the rotary heads 18 and 19 are respectively provided with the magnetic tape 20.
Since the time-axis compressed PCM audio signal is recorded during the overlap period after the start of contact with the recording medium, and the combined signal is recorded from the adding circuit 10 during the next 180 ° rotation period, the second signal is recorded on the magnetic tape 20.
As shown in the figure, a part (hereinafter referred to as an overlap part) 76 in which a second composite signal of the time-axis compressed PCM audio signal and the pilot signal is recorded, and a part of the video signal, the FM audio signal and the pilot signal are recorded. A track, which is continuous with a portion (hereinafter, referred to as a video recording portion) 75 in which one composite signal is recorded, is sequentially formed obliquely with respect to the longitudinal direction of the magnetic tape 20. Since the rotary heads 18 and 19 have different azimuth angles, no guard band is provided between the tracks.

At the time of reproduction, as shown in FIG. 4, the mode setting signal 4A supplied from the input terminal 38 to the system controller 34 is "H", and the mode setting signals 4D and 4B supplied from the input terminals 38 'and 39, respectively. Is set to "L". As a result, the switches 16 and 17 are switched to the PB side.

The rotary heads 18 and 19 respectively include an overlapping portion 76 (second
The second composite signal is reproduced when scanning (FIG. 2) and the first composite signal is reproduced when scanning the video recording portion 75 (FIG. 2).

The reproduction signal of the rotary head 18 passes through the switch 16 and the amplifier 40.
Is amplified by and is supplied to the a side of the switches 42.43, the reproduction signal of the rotary head 19 passes through the switch 17, is amplified by the amplifier 41, and is supplied to the b sides of the switches 42 and 43. Switch 42,
The switch 43 is controlled by the switching signal 4c from the switching signal generator 11, whereby the switch 42 causes the rotary head 18 to perform a reproduction scan of the video recording portion 75 (FIG. 2) of the magnetic tape 20 (this period). The period includes the period in which the rotary head 18 reproduces and scans the overlapping portion 76 (FIG. 2)),
A period other than a period in which the rotary head 19 closes to the side a and reproduces and scans the video recording portion 75 of the magnetic tape 20 (this period includes a period in which the rotary head 19 reproduces and scans the overlapping portion 76), and side b Close to. Therefore, from the switch 42, the time-axis compression PCM reproduced alternately by the rotary heads 18 and 19.
The second combined signal of the voice signal and the pilot signal is intermittently obtained. The switch 43 is closed to the side a when the rotary head 18 reproduces and scans the video recording portion 75, and closes to the side b when the rotary head 19 reproduces and scans the video recording portion 75. Therefore, from the switch 43, the rotary heads 18, 19
The first composite signal of the video signal, the FM audio signal, and the pilot signal, which are alternately reproduced by, is continuously obtained.

The first combined signal from the switch 43 is supplied to the ATF control circuit 44, and the pilot signal of this combined signal and the pilot signal from the pilot signal generator 8 form a phase control signal. The rotation phase of the capstan motor 45 is controlled by this phase control signal, and tracking control of the rotary heads 18 and 19 is performed. In this way, the ATF control method is a tracking control method performed by recording a pilot signal mixed with a video signal and reproducing the pilot signal.

Further, the first combined signal from the switch 43 is supplied to the FM voice reproduction processing circuit 46, the luminance signal reproduction processing circuit 47 and the chroma signal reproduction processing circuit 48, respectively. FM voice reproduction processing circuit
At 46, the FM audio signal is separated from the first synthesized signal
Processing such as demodulation is performed to obtain the original first audio signal. This first audio signal is supplied to the output terminal 68.
In the luminance signal reproduction processing circuit 47, the FM luminance signal is separated from the first combined signal, and processing such as FM demodulation is performed to obtain the original luminance signal. In the chroma signal reproduction processing circuit 48,
The low-frequency conversion chroma signal is separated from the first combined signal, and processing such as frequency conversion is performed to obtain the chroma signal in the original band. The luminance signal and the chroma signal are added by the adder circuit 49 to form the original video signal, and this video signal is supplied to the output terminal 69 via the adder circuit 67.

On the other hand, the second combined signal from the switch 42 is supplied to the equalization circuit 50, where the time-axis compressed PCM voice signal and the like are waveform-equalized, and then the data strobe circuit 51 reproduces the data to obtain a PCM signal. Become. This PCM signal is supplied to the PCM decoder 52 and subjected to processing such as time-axis expansion and error correction, and then converted into an analog audio signal by a digital-analog converter (hereinafter referred to as D / A converter) 53. This audio signal is sent to the sample and hold circuit (ie S / H circuit) 54
Is supplied to the main signal and separated into the main signal and the sub signal, and the main signal is LP
The auxiliary signal is supplied to the output terminal 64 via the F55 and the noise suppression circuit (that is, the NR circuit) 57, and the sub signal is supplied to the output terminal 65 via the LPF 56, the NR circuit 58 and the switch 62. Therefore, the second audio signal is obtained at the output terminals 64 and 65. The NR circuits 57 and 58 extend the dynamic range of the main and sub signals to the original state, respectively.

The basic operation of this embodiment is as described above. However, in addition to such operation, this embodiment has an effect on this video signal in which character data representing character information to be super-imposed on the video signal is recorded. Recording and reproduction can be performed without giving. Hereinafter, this point will be described.

The character image based on this character signal can be super-imposed at an arbitrary position on the reproduced image based on the video signal. Therefore, while reproducing the video signal recorded on the magnetic tape 20, the character image can be reproduced at an arbitrary timing. The data is recorded on the magnetic tape 20, and this character data is recorded when the rotary heads 18 and 19 are in the overlap period. Therefore, at this time, the rotary heads 18 and 19 are set to the so-called after-recording mode (hereinafter referred to as the after-recording mode), which is in the recording mode during the overlap period and in the reproducing mode during the other periods. Magnetic tape 20
After-recording for recording a signal in the overlapping portion 76 (Fig. 2) of the same can be performed for the second audio signal, but in any case, in the after-recording mode, the input terminals 38, 38 'are used. The mode setting signals 4A and 4B supplied from the system controller 34 to the system controller 34 are "H".

At this time, the switch 16 is closed to the REC side when the rotary head 18 is in the overlap period, and is closed to the PB side when the rotary head 18 is in the other period. The switch 17 is similarly switched according to the scanning period of the rotary head 19 with the magnetic tape 20. Therefore, the rotary heads 18 and 19 are in the reproduction mode when reproducing the first composite signal when scanning the video recording portion 75 of FIG. 2 respectively, and when scanning the overlap portion 76, In the recording mode, the output signals of the amplifiers 14 and 15 are recorded.

Here, when the mode setting signal 4B is “L”, the control signal
4E is "L", the switches 23 and 24 are closed to the side a, and the character data control circuit 35 does not operate. At this time, as described above, the second audio signal from the input terminals 3 and 4 can be recorded in the overlapping portion 76 (FIG. 2) on the magnetic tape 20.

In the case of after-recording character data, the mode setting signal 4D supplied from the input terminal 39 to the system controller 34 is further added in the after-recording mode.
Is set to "H" as shown in FIG. As a result, the control signal 4E output from the system controller 34 becomes "H" as shown in FIG. 4, and the switches 23 and 24 are closed to the b side. Further, the character data control circuit 35 operates and the character data generation circuit 36 generates character data.

This character data is modulated to the FS by the circuit 37 in the same band as the second voice signal, and is sent to the S via the switch 24, LPF 26 and NR circuit 28.
/ H is supplied to the circuit 29. Here, as explained above,
The second audio signal may be recorded simultaneously with the video signal or by post-recording after the video signal has been recorded. Hereinafter, this second audio signal shall be recorded simultaneously with the character data. In this case, the second audio signals from the input terminals 3 and 4 are added by the adding circuit 22 to become a channel signal, and the S / H circuit is passed through the switch 23, the LPF 25 and the NR circuit 27.
Supplied to 29. In the S / N circuit 29, the second voice signal and the character data are time-division multiplexed, and the A / D converter 30
After being digitized by the PCM encoder, time axis compression, error correction parity addition, discrimination signal generator 32
Processing such as addition of ID signals and modulation suitable for recording is performed. The ID signal at this time represents a monaural signal and character data. The output signal of the PCM encoder 31 is, after the pilot signal is added in the adding circuit 33,
It is supplied to the switch 16 via the switch 12 and the amplifier 14,
On the other hand, it is supplied to the switch 17 via the switch 13 and the amplifier 15. As a result, the character data is recorded together with the second audio signal in the overlapping portion 76 in a continuous manner with the already formed video recording portion 75 in FIG.

Therefore, even if the character data is recorded on the magnetic tape 20, the video signal already recorded on the video recording portion 75 is not affected by erasing or the like.

On the other hand, the first combined signal reproduced by the rotary head 18 is supplied to the a side of the switches 42 and 43 via the switch 16 and the amplifier 40, and the first combined signal reproduced by the rotary head 19 is switched to the switch 17, Switch 42,43 via amplifier 41
Is supplied to the b side of the switch 43, and a continuous first combined signal is obtained from the switch 43. No signal is obtained from the switch 42. The first combined signal is subjected to the above processing, and as a result, the first audio signal is obtained at the output terminal 68 and the video signal is obtained at the output terminal 69. These are supplied to a monitor (not shown) for video image reproduction and audio reproduction.

When the PCM encoder 31 does not output the PCM signal, the rotary heads 18 and 19 only reproduce the first composite signal recorded in the video recording portion 73 (FIG. 2) (that is, in the reproduction mode). Although the image is being reproduced on the monitor, when a desired scene is displayed on this monitor, a "H" mode signal 4D from the input terminal 39 to the system controller 34 is supplied to the system controller 34 by means not shown. To supply superimpose mode. As a result, it is possible to post-record character data at a desired timing.

The PCM recorded in the overlap part 76 (Fig. 2)
The signal is, as shown in FIG. 3, a clock run IN for forming a clock for time axis expansion in the PCM decoder 52.
It is composed of Cin, a synchronous portion S _Y, and a data portion D, and the data portion D includes voice data, character data, an ID signal, and an error correction signal. Further, a guard portion G is provided between the video recording portion 75 and the overlap portion 76.

The second audio signal and the character data are post-recorded as described above. Next, in the case of reproducing the magnetic tape on which the character data is post-recorded and superimposing the character information on the reproduced image of the video signal. explain.

In this case, the reproduction mode as shown in FIG. 4 is set, and the second combined signal is obtained from the switch 42 and the first combined signal is obtained from the switch 43 in the same manner as in the case of the reproduction described above. A composite signal is obtained. When the rotary heads 18 and 19 reproduce and scan the overlap portion 76 (FIG. 2) in which the character data is recorded, the second combined signal from the switch 42 includes the character data. The first synthesized signal is processed as described above to obtain the first audio signal at the output terminal 68 and the video signal at the output terminal 69. The second synthesized signal is also processed as described above, and the second audio signal is obtained at the output terminals 64 and 65.

When the rotary heads 18 and 19 reproduce and scan the overlapped portion 76 in which the character data shown in FIG. 2 is recorded, the switch 42 produces a second monaural voice signal and a second composite signal composed of the character data. , To the PCM decoder 52.
At this time, the discrimination signal detection circuit 60 detects the ID signal representing the character data from the second combined signal and outputs the control signal 5F which is in the character data period "H" as shown in FIG.
As a result, the switch 62 keeps b during the period of the control signal 5F.
Switch to the side.

Therefore, the second audio signal is the D / A converter 53, the S / H circuit 54, L
It is supplied to the output terminal 64 via the PF 55 and the NR circuit 57, and is also supplied to the output terminal 65 via the switch 62.

On the other hand, the character data passes through the D / A converter 53, is separated from the second audio signal by the S / H circuit 54, and then is supplied to the FSK decoder 70 via the LPF 56 and the NR circuit 58, and the original signal form is obtained. And is supplied to the character data generation circuit 73. The reading of character data from the memory of the character data generation circuit 73 is controlled by the character data control circuit 74. That is, the video signal output from the adder circuit 49 is supplied to the sync separation circuit 66, and the sync signal is separated. However, the character data control circuit 74 is triggered by this sync signal to generate the character data generator 73.
The character data is read from the memory at a predetermined number of times in synchronization with the video signal. Therefore, the character data generating circuit 73 repeatedly outputs the character signal a predetermined number of times, and the adding circuit 67
Is supplied to the output terminal 69.

In this way, character information such as a title is superimposed on the monitor.

By the way, when the character data reproduced by drop-up or the like has a remarkable omission, even if the character information is displayed on the monitor, it may be unclear and difficult to see. In this case, it is preferable not to superimpose the character information.

Therefore, the PCM decoder 52 corrects the error of the second combined signal. When the second combined signal is uncorrectable, a signal indicating this, that is, an uncorrectable error signal is supplied to the error amount identification circuit 59. When the frequency of the uncorrectable error signal is low, the output signal 5G of the error amount identification circuit 59 is "L", but when the frequency is high, the output signal 5G becomes "H".

When the character data is largely lost due to dropout or the like, the frequency of the uncorrectable error signal at that time becomes higher than a preset reference value, and the output signal 5G of the error amount identification circuit 59 becomes "H". The timing when the output signal 5G becomes "H" is as shown in FIG.
This coincides with the timing of the control signal 5F representing the character data period output from 60. From the coincidence of the timings of these signals, the character data output operation determination circuit 61 determines that the character data is largely missing, and at the same time when the control signal 5F ends, the output of that output is performed as indicated by the broken line in FIG. Set the signal to “H”. The character data generation circuit 73 tries to start reading the character data at the end of the control signal 5F, but the character data output operation determination circuit 61 outputs the “H” output signal 5H.
The switch 63 is opened by this, and the control signal obtained by inverting this output signal 5H by the inverter 71 deactivates the character data control circuit 74. Therefore, the superimposing operation of character information is prohibited.

At the same time, the output signal 5H of the character data output operation determination circuit 61 is also supplied to the error display circuit 72, which indicates that the superimposing operation of the character information is prohibited.

As described above, in this embodiment, desired character information can be superimposed on the video image on the monitor, but the character data is recorded on a portion different from the portion where the video signal is recorded on the magnetic tape. Since it is recorded, the recorded video signal is not erased by the recording of the character data. In addition, when the character data is affected by the dropout, it is possible not to superimpose the character information. In this case, the video signal is not erased by the recording of the character data. Is displayed without omission. Moreover, when the text information is not superimposed,
Since this can be displayed, the reliability of the superimpose function is improved.

FIG. 6 is a block diagram showing another embodiment of the video tape recorder according to the present invention, in which 77 is a memory, 78 is a switch, 79 is an error amount identification circuit, and the parts corresponding to those in FIG. A duplicate description will be omitted by giving a reference numeral.

In the embodiment shown in FIG. 1, the character data is recorded only once, but in the embodiment shown in FIG. 6, the same character data is recorded twice, and one of them is displayed by a dropout or the like. When it cannot bear, it superimposes the other to reduce the effect of dropouts.

In FIG. 6, by setting the mode setting signals 4A and 4B supplied from the input terminals 38 and 40 to the system controller 34 to “H” (FIG. 2), the after-recording mode is set as described above. , Furthermore, by setting the mode setting signal 4D supplied from the input terminal 39 to “H”, the switch 2
3, 24 is switched to the b side, and character data is generated from the character data generation circuit 36. In this case, the system controller 34
As shown in FIG. 7, the control signal K of "H" is generated twice, so that the same character data is continuously generated twice from the character data generation circuit 36. Now, in order to distinguish these same character data, as shown in FIG.
When different signs of are added, these character data A and B are
Similar to the embodiment shown in FIG. 1, the magnetic tape 20 is recorded on the overlapping portion 76 (FIG. 2), but the same character data is recorded on the magnetic tape 20 twice. . In this case, the character data A and B are recorded at different positions on the magnetic tape 20, but they may be different positions of the same overlapping portion 76 or different overlapping portions 76. Further, in the PCM encoder 31, each character data is added with an ID signal representing it.

At the time of reproduction, the character data A,
The ID signal is detected for each B, and the character data A, B
The control signal 5I shown in the figure is generated. By this control signal 5I, first, the switch 62 is closed to the b side, and the NR circuit
The character data A from 58 is supplied to and stored in the character data generation circuit 73 via the FSK data 70, and then, similarly, the character data B is supplied to and stored in the character data generation circuit 77. In this case, the character data control circuit 74 is controlled by the control signal 5I. First, the memory of the character data generation circuit 73 is set to the writing code of the character data A, and then the memory of the character data generation circuit 77 is set to the writing mode of the character data B. To do.

On the other hand, the data amount identification circuit 79 measures the frequency of each uncorrectable error signal of the character data A and the character data B based on the control signal output from the discrimination signal detection circuit 60, and compares the magnitudes of both. , It is determined whether or not both are above the reference value.

Now, assuming that the frequency of the uncorrectable error signal of the character data A is smaller than that of the character data B, and both are smaller than the reference value, the error amount identification circuit 79 outputs the control signal as shown in FIG. 5J is generated and the switch 78 is closed to the A side. In addition, the control signal output from the error amount identification circuit 79
5H is “L” as shown by the solid line in FIG.
63 closes. As a result, a character signal is output from the character data generating circuit 73 and added to the video signal by the adding circuit 67 to superimpose the character information on the monitor.
Similarly, when the frequency of the uncorrectable error signal of the character data B is smaller than that of the character data A, the character data generation circuit 77 outputs the character signal and superimposes the character information. Thus, the character data A,
Of B, the one with less frequency of uncorrectable error is superimposed, and since they have the same content, the characters with good image quality are superimposed and displayed on the monitor.

When the frequency of the uncorrectable error signals of the character data A and B is equal to or higher than the reference value, the control signal 5H output from the error amount identification circuit 79 becomes "H" as shown by the broken line in FIG.
This causes the error display circuit 72 to display that the switch 63 is opened and superimpose is prohibited.

FIG. 9 is a block diagram showing still another embodiment of the video tape recorder according to the present invention, in which 80 is a character data recording control circuit and 81 is a character data reproduction control circuit. Are given the same symbols.

In the embodiment shown in FIGS. 1 and 6, when the character data is recorded, the second audio signal becomes a monaural signal. However, in the embodiment shown in FIG. 9, the character data is recorded. However, the second audio signal can be any of monaural, multiplexed, and stereo signals.

In FIG. 9, the PCM encoder 31 adds an ID signal indicating whether it is monaural, multiplex, or stereo to the second audio signal.
The character data generation circuit 36 generates character data while the ID signal is generated. The character data supplies the character data to the PCM encoder 31 by driving the character data recording control circuit 80 and controlling the discrimination signal generator 32. Therefore, the character data is recorded in the area of the overlap portion 76 (FIG. 2) where the ID signal is recorded. Therefore, the second audio signal from the input terminals 3 and 4 can be recorded without being converted into a monaural signal.

At the time of reproduction, the discrimination signal detection circuit 60 is an ID including character data.
A signal is detected, and a control signal 5F representing the period of character data is generated from this ID signal as described above. The ID signal detected by the discrimination signal detection circuit 60 is supplied to the character data reproduction control circuit 81, and the character data is separated and supplied to the character data generation circuit 73.

The embodiment of the present invention has been described above. However, the present invention is not limited to the stop of the superimposing operation of the character information due to a dropout, the error display, and the selection of the character data shown in the embodiment of FIG. It is obvious that the above means may be used, or the same character data may be recorded three or more times and any one of them may be selected and superimposed. Furthermore, in the embodiment shown in FIG.
Any method of recording character data as an ID signal can be adopted. Other image information such as a figure other than the character information may be superimposed.

〔The invention's effect〕

As described above, according to the present invention, data of arbitrary image information can be recorded on a magnetic tape on which a video signal is already recorded, without damaging the video signal, and the data can be dropped out or the like. When impaired, the superimposition of the image information can be prohibited, the reproduced image for the video signal is not affected at all, and further, the prohibition of the superimposition of the image information is accompanied. Can be displayed and the reliability of the superimpose function is high, and the problems of the above-mentioned prior art can be solved to provide a video tape recorder having an excellent function.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a video tape recorder according to the present invention, FIG. 2 is a schematic diagram showing a track pattern on a magnetic tape, and FIG. 3 is recorded in an overlap portion shown in FIG. Schematic diagram showing an example of PCM signal, No. 4
5 and 5 are timing charts for explaining the operation of the embodiment shown in FIG. 1, and FIG. 6 is a block diagram showing another embodiment of the video tape recorder according to the present invention, FIGS. 7 and 8. FIG. 9 is a timing chart for explaining the operation, and FIG. 9 is a block diagram showing still another embodiment of the video tape recorder according to the present invention. 1 …… Video signal input terminal, 20 …… Magnetic tape, 23 ……
Switch, 30 ... Analog-digital converter, 31 ... PC
M encoder, 32 …… discrimination signal generator, 34 …… system controller, 35 …… character data control circuit, 36 …… character data generation circuit, 52 …… PCM decoder, 59 …… error amount identification circuit, 60 …… Discrimination signal detection circuit, 61 ... Character data output operation determination circuit, 62, 63 ... Switch, 67 ... Addition circuit, 69 ... Video signal output terminal, 72 ... Error display circuit, 73 ... Character data generation circuit , 74 ... Character data control circuit, 75 ... Video recording part, 76 ... Overlap part, 77 ... Character data generation circuit, 78 ... Switch, 79 ...
… Error amount identification circuit, 80 …… Character data recording control circuit, 81 …… Character data reproduction control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuzumi Wataya, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Home Appliances Research Laboratory, Hitachi, Ltd. (72) Inventor Yasuhide Mogi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (56) References JP 58-164383 (JP, A) JP 58-166886 (JP, A) Actual development Sho 58-176469 (JP, U)

Claims (2)

[Claims] 1. A recording track is formed on a magnetic tape, the recording track being inclined at a constant angle with respect to the longitudinal direction of the magnetic tape, and the end portion of the recording track is extended to record a digital audio signal. A video tape recorder adapted to record a modulated analog video signal, means for generating digital image data, modulation means for adding an error correction code to the digital image data, and modulating for recording. Means for recording the modulated digital image data in a portion of the recording track where a digital audio signal is recorded; means for reproducing the FM-modulated analog video signal and the modulated digital data from the recording track; A means for demodulating the FM-modulated analog video signal into an original analog video signal, Means for demodulating the modulated digital data into original digital data, means for extracting the digital image data from the demodulated digital data and converting it into an analog image signal, and an error for the demodulated digital data Means for detecting using the above-mentioned error correction code added to the above, an error number detecting means for detecting whether or not the number of detected errors is a certain number or more, and control by the detection output of the error number detecting means When the number of errors is less than the fixed number, the analog image signal is superimposed on the demodulated analog video signal, and when the number of errors is equal to or larger than the fixed number, the demodulated analog video signal is demodulated. And superimposing means for stopping the superimposing operation of the analog image signal. Video tape recorder. 2. A recording track is formed on a magnetic tape, the recording track being inclined at a constant angle with respect to the longitudinal direction of the magnetic tape, and the end portion of the recording track is extended to record a digital audio signal. A video tape recorder adapted to record a modulated analog video signal, means for generating digital image data, modulation means for adding an error correction code to the digital image data, and modulating for recording. Means for repeatedly recording the modulated digital image data of the same information content a plurality of times in the portion of the recording track where the digital audio signal is recorded, and the FM modulated analog video signal and the modulated digital data from the recording track. Means for reproducing the analog video signal based on the reproduced FM-modulated analog video signal. Means for demodulating into a signal, means for demodulating the reproduced modulated digital data into original digital data, and for each digital image data in the demodulated digital data, the error is added to this A means for detecting using an error correction code, a comparing means for comparing the number of errors detected from digital image data having the same information content, and the digital data demodulated according to the comparison result of the comparing means. From the digital image data having the same information content as described above, the digital image data with the smallest number of errors is extracted and converted into an analog image signal, and the smallest number of errors detected by the comparison means is a certain number or more. It is controlled by the error number detecting means for detecting whether or not there is an error number and the detection output of the error number detecting means. If the number of small errors is less than the fixed number, the demodulated analog video signal is superimposed on the analog image signal obtained from the extracting means, and if the smallest number of errors is the fixed number or more, demodulation is performed. And a superimposing means for stopping the superimposing operation of the analog image signal to the analog video signal.