JP3167528B2 - Video tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder (hereinafter referred to as "VTR") such as an 8 mm video tape recorder which performs ATF head tracking using a tracking pilot signal. The present invention relates to the adjustment (switching) of the recording current in response.

[0002]

2. Description of the Related Art Conventionally, an 8 mm VTR is formed into a camera-integrated video movie and is frequently used for shooting and recording. In this case, when the power of the VTR is turned on and the recording (movie) is set, a recording (recording) pause mode is set. Thereafter, the recording mode is alternately changed to a recording mode and a recording pause mode by operating the recording button. So-called connection recording is performed.

In the recording mode, an FM precision signal and a low-frequency conversion color signal, an FM audio signal, and a tracking pilot signal on the low frequency side of this signal are provided in a time-division video area of each helical scan track of the magnetic tape. The frequency multiplexed recording signal is converted into a recording current and recorded.

Further, when the recording tape is shifted to the recording pause, the next recording start point is caused by a slight overrun of the magnetic tape without stopping at the recording end point or a slack of the tape caused by turning on / off the power supply. In order to prevent the data from becoming inconsistent with the recording end point, and to enable horizontal synchronization (H arrangement) at the start of the next recording, the magnetic tape is rewound by a predetermined amount by a short rewind operation, and then the recording pause is started. .

On the other hand, magnetic tapes of 8 mm VTR are currently roughly classified into two types of tapes: metal vapor deposition tape (ME position tape) and metal coating tape (MP position tape). The tape in the ME position has a feature that both the magnetic layer and the tape base are thin so as to be suitable for high-density recording, and exhibit higher performance than the tape in the MP position for recording in a high frequency range.

[0006] This is because, when the magnetic layer is thin, a decrease in reproduction output due to thickness loss in a high frequency range is reduced. On the other hand, due to the thinness of the magnetic layer, the tape in the ME position has a lower reproduction output in the low range than the tape in the MP position.

Therefore, conventionally, the recording current condition is changed according to the tape to be used by selecting the tape position, and when recording is performed using the tape at the ME position, the low-frequency conversion color signal, the FM audio signal, the pilot The recording current of the composite signal (low-frequency signal) is increased by about 2 dB compared to when recording is performed using a tape at the MP position, and recording is performed while compensating for a decrease in reproduction output in the low frequency range. I have.

[0008]

The conventional 8 mm VT
In the case of R, there is a problem that operability cannot be improved because recording is performed by changing a recording current condition according to a tape to be used by selecting a tape position.

Recently, tape characteristics have been diversified, and ME
There is a tape having a large low-frequency reproduction output even for a tape in a position, and a tape having a low reproduction output in a low frequency even for a tape in an MP position. Therefore, ME position,
If the recording current condition is changed only by the type of tape called the MP position, erroneous setting of the condition occurs, and proper recording cannot be performed.

That is, if the recording current condition is erroneously set, if the tape to be recorded is a tape at the ME position where the low-frequency reproduction output is large, a low-frequency side signal such as a low-frequency conversion color signal or the like is used more than necessary. In this case, white and black granular noise (color and blur) and beats are generated on the playback screen, and if the tape is at the MP position where the low-frequency reproduction output is small, the low-frequency signal Recording level becomes too low, the S / N is degraded, or the reproduction screen is disturbed in synchronization.

The present invention relates to a VTR for performing ATF head tracking using a tracking pilot signal such as an 8 mm VTR, which does not require a tape position selection operation and uses a recording current condition to improve the recording characteristics of a tape. The purpose is to automatically set optimal conditions.

[0012]

In order to achieve the above object, in the case of the VTR of the present invention according to claim 1, a gain switching circuit for amplifying a low-frequency signal by a set gain and adjusting a level, Adjustment level initialization means for resetting the set gain to the initial gain upon detection of the replacement of the recording magnetic tape, and operation mode control for recording the recording current after resetting the set gain on the magnetic tape for a certain period and then rewinding the tape in a reproducing state Means for adjusting a set gain according to a difference between a reproduction level of a tracking pilot signal of a tape reproduction output obtained by rewinding the reproduction state and a reference level;
Gain control means for variably setting the adjustment level of the low-frequency signal according to the recording magnetic tape.

Further, in the case of the VTR according to the present invention, a gain switching circuit for amplifying a low-frequency signal by a set gain and adjusting the level, and initializing the set gain by detecting a mode transition to a recording pause. Adjustment level initialization means for resetting to a gain, delaying the mode transition to a recording pause, recording the recording current after resetting the set gain on a magnetic tape for a certain period of time, rewinding the tape in a reproducing state, and then performing the recording. An operation mode control means for controlling a pause, and a set gain adjusted in accordance with a difference between a reproduction level of a tracking pilot signal of a tape reproduction output obtained by rewinding the reproduction state and a reference level, and a low-frequency signal Gain control means for variably setting the adjustment level for the recording magnetic tape.

[0014]

The VTR according to claim 1 configured as described above.
In the case of, the set gain of the gain switching circuit is reset to the initial gain by the adjustment level initialization means for each conversion of the magnetic tape to be recorded, and after this reset, the operation mode control means controls the low-frequency side amplified by the initial gain. Is recorded on the magnetic tape for a certain period of time, and then the tape is rewound in a reproducing state.

At this time, the level of the pilot signal of the tape reproduction output obtained by rewinding the reproduction state changes in magnitude according to the recording characteristics of the magnetic tape to be recorded. Then, the gain control means adjusts the gain set in the gain switching circuit according to the difference between the level of the pilot signal of the tape reproduction output and the reference level.

[0016] Therefore, each time the recording magnetic tape is replaced, the amplification level of the signal on the low frequency side is variably adjusted without performing the conventional operation of selecting the tape position, and the recording current condition depends on the condition of the recording tape. Automatically set to optimal conditions for recording characteristics.

In the case of the VTR according to the second aspect, VT
Immediately after the power of R is turned on or when the mode transition to the recording pause occurs due to the recording stop operation, before the transition to the recording pause,
The set gain of the gain switching circuit is reset to the initial gain by the adjustment level initialization means.

Further, after a recording current including the low-frequency signal amplified by the initial gain is recorded on the magnetic tape for a certain period by the operation mode control means, the tape is rewound in a reproducing state, and the rewound is performed. After the recording pause is controlled.

The level of the tracking pilot signal of the tape reproduction output obtained by rewinding the reproduction state changes according to the characteristics of the magnetic tape to be recorded, and the level of the pilot signal of the tape reproduction output is changed by the gain control means. The set gain of the gain switching circuit is adjusted according to the difference from the reference level.

Therefore, each time the operation mode is set to the recording pause, that is, immediately before the next recording, the amplification level of the low-frequency side signal is changed to the recording characteristic of the magnetic tape without performing the conventional tape position selection operation. The recording current condition is automatically set to an optimum condition for the recording characteristics of the magnetic tape to be used.

[0021]

An embodiment will be described with reference to FIGS. (One Embodiment) First, one embodiment will be described. FIG. 1 shows a case in which the present invention is applied to an 8 mm VTR. When power is turned on, recording is set, and when a recording button of the operation unit 1 is operated to enter a recording mode, an F formed by a luminance signal process such as an imaging output.
The M luminance signal S ₁ is supplied from the luminance recording terminal 2 to the adder 3.

Also, a low-frequency conversion color signal S ₂ formed by color signal processing such as image pickup output, an FM audio signal S ₃ formed by microphone input audio signal processing, and a tracking pilot signal generated by pilot signal generation. S ₄ color recording terminal 4, audio recording terminal _{5 is} supplied from the tracking record terminal 6 to the adder 7.

The frequency allocation of each of the signals S _{1 to} S ₄ is, in order from the low frequency side, a tracking pilot signal S ₄ , a low-frequency conversion color signal S ₂ , and an FM audio signal S ₃ , F
It becomes the M luminance signal S ₄ , and the FM luminance signal S ₄ forms the luminance signal on the high frequency side. The tracking pilot signal S ₄ cyclically changes to four frequencies in a field (track) cycle.

[0024] Then, the low-band converting chrominance signal S _2, FM audio signal S _3, the signal S ₅ lower frequency obtained by combining the tracking pilot signal S ₄ is formed by the signal adder of the adder 7,
The signal S ₅ is supplied to the gain switching circuit 8.

The switching circuit 8 is formed of, for example, a variable gain amplifier, amplifies the signal S ₅ with a set gain, adjusts the level, and supplies the adjusted signal S ₅ to the adder 3.

[0026] Then, the adder 3 recording signal S ₆ FM luminance signals S ₁ and the signal S ₅ on the low-range side after level adjustment high band side is added is formed by, the signal S ₆ is a recording amplifier 9 Supplied to

Further, the amplifier 9 records the recording signal S _6.
There recording current is converted to S _7, the recording current S ₇ is supplied to the magnetic head 11 of the pair of the head cylinder 10.

Then, the capstan motor 13 is driven by the control circuit 12 of the microcomputer, and the magnetic tape (recording tape) 15 of the tape cassette mounted by the cassette loading mechanism 14 is wound around the head cylinder 10 and travels. The recording of the magnetic tape 15 is performed by the helical scan of the magnetic head 11.

This recording is performed by operating the recording button of the operation unit 1,
Control circuit 1 changes mode from recording mode to recording pause
2, and stops by controlling the mechanism and the like to the recording pause. Also, when moving to this recording pause,
The magnetic tape 15 is rewound by a predetermined amount by the short rewind control of the control circuit 12.

Next, in order to reset the set gain of the gain switching circuit 8 every time the magnetic tape to be recorded is changed, the control circuit 12 has the following units. i) recording a certain period the recording current S ₇ after reset setting gain adjustment level initialization means ii) a gain switching circuit 8 to reset the exchange detection of the magnetic tape 15 to set the gain of the gain switching circuit 8 to the initial gain magnetic according to the difference between the rewind the tape 15 by the reproducing state operating mode control means iii) a tape reproduction output of the tracking pilot signal S ₄ obtained by rewinding the playback state playback level and the reference level after recording on the tape 15 adjust the gain setting of the gain switching circuit 8 Te, gain control means for variably set in accordance with the magnetic tape 15 to record the adjustment level of the signal S ₅ lower frequency

When the magnetic tape 15 to be recorded is replaced, the control circuit 12 detects the replacement based on the loading information of the cassette loading mechanism 14.

Based on this detection, the adjustment level initialization means supplies a reset signal to the gain switching circuit 8, and resets the gain set in the switching circuit 8 to the initial gain.

Further, the operation mode control unit controls the automatic recording mode, recording of the gain switching immediately after the reset of the gain setting of circuit 8, a period of time of several seconds based on the recording current S ₇ on the magnetic tape 15 after replacement Is performed.

[0034] At this time, the signal S ₅ lower frequency regardless of the gain setting of the immediately preceding gain switching circuit 8, always be recorded is amplified by an initial gain. Further, when the recording for the predetermined period is completed, the operation mode control means controls a rewind mode (short rewind mode) in a reproducing state, and the magnetic tape 15 is rewound for a predetermined period while being reproduced by the magnetic head 11 by this control. .

At this time, the reproduction output of the magnetic tape 15 is taken out as a reproduction current S ₈ by the magnetic head 11, and the reproduction current S ₈ is converted into a reproduction signal S ₉ by the reproduction amplifier 16.

[0036] The reproduction signal S ₉ is supplied to the ATF · AGC circuit 17, the circuit 17 is configured as shown in FIG. 2, to extract the component of the tracking pilot signal S ₄ by the low-pass filter 17a, a filter 17a The output signal is supplied to the AGC detection circuit 1 via the AGC amplifier 17b.
7c, and the detection voltage of the detection circuit 17c
The gain of the GC amplifier 17b is feedback controlled, taking out the AGC corrected reproduced pilot signal S ₁₀ at a constant level.

At this time, the time constant pin 1 of the detection circuit 17c
Signal S ₁₁ of the detection voltage corresponding to the input voltage of the AGC amplifier 17b is generated 7d, the signal S ₁₁ is reproduced pilot signal before AGC correction. The time constant pin 17d is connected to a time constant capacitor 17e.

[0038] Then, when the signal S ₁₁ of the detection voltage constant pin 17d is supplied to the ATF level detection circuit 18, the detection circuit 18 is a signal S ₁₁ by integrating smooth detects the signal level, the reproduction pilot signal Signal level detection signal S
₁₂ is supplied to a comparator 19.

[0039] The comparator 19 compares the reproduction level and the reference level is compared with the reference signal of the internal and the detection signal S ₁₂ a tracking pilot signal S _4, the gain switching circuit when reproduction level is less than the reference level 8 is commanded to correct the set gain, and when the reproduction level is higher than the reference level, the gain switching circuit 8 is commanded to correct the decrease of the set gain.

[0040] Then, the gain switching circuit 8, when it is commanded to rise correction setting gain, increased by a unit quantity corresponding to the increase of about 2dB of gain setting, for example, the recording current S _7, the descending correction setting gain When the command is issued, the set gain is reduced by an amount corresponding to the amount of increase, for example.

Therefore, every time the magnetic tape 15 to be recorded is replaced, the gain set in the gain switching circuit 8 is variably corrected from the initial gain according to the recording characteristics of the replaced magnetic tape 15, and the low-frequency side signal S The recording current condition of ₅ is automatically set to an optimum characteristic according to the recording characteristic of the magnetic tape 15.

At this time, since the set gain is variably corrected based on the actual recording on the magnetic tape 15, the recording characteristic is automatically set to the optimum characteristic regardless of the characteristic of the magnetic tape 15 to be recorded. You.

Next, another embodiment will be described. In this embodiment, the control circuit 12 includes the following units in order to reset the gain of the gain switching circuit 8 every time the mode shifts to the recording pause. i) adjustment level initialization means for resetting the set gain to the initial gain upon detection of the mode transition to the recording pause; ii) delaying the mode transition to the recording pause and resetting the set gain of the gain switching circuit 8 the recording current S ₇ recorded for a period of time the magnetic tape 15, the tracking of the tape reproduction output obtained by returning the operation mode control unit iii) of the reproduction state winding for controlling the recording pause after rewinding in play mode the tape 15 gain control means for reproduction level of the pilot signal S ₄ adjusts the gain setting of the gain switching circuit 8 to a predetermined level, variably set in accordance with the magnetic tape 15 to record the adjustment level of the signal S ₅ lower frequency

When the control circuit 12 is instructed to turn off the power or to switch the operation mode from the recording mode to the recording pause by turning on the power or operating the recording button of the operation unit 1, the adjustment level initialization means resets the reset signal. To the gain switching circuit 8
To reset the set gain of the switching circuit 8 to the initial gain.

Further, the operation mode control means delays the mode shift to the recording pause, and the control to the recording mode or the continuation of the recording mode causes the recording current S to be applied to the magnetic tape 15 immediately after the reset of the gain set in the gain switching circuit 8. Record for a fixed period of about several seconds based on ₇ . When the recording is completed, the operation mode control means shifts to the control of the short rewind operation in the reproduction state of the magnetic tape 15.

Under this control, the magnetic tape 15 is rewound while being reproduced in the same manner as in the first embodiment, and the detection signal S ₁₂ of the reproduction pilot signal of the detection circuit 18 based on the reproduction current S ₈ is sent to the comparator 19. Supplied to this comparator 19
Instructs the gain switching circuit 8 to increase and decrease the set gain in the same manner as in the first embodiment.

According to this correction command, the gain set in the gain switching circuit 8 is variably set in accordance with the recording characteristics of the magnetic tape 15. When the short rewind operation is completed, the operation mode control unit controls the recording pause mode.

Therefore, in this embodiment, the gain set in the gain switching circuit 8 is reset every time the mode is changed to the recording pause mode, that is, immediately before the next connection recording, and the same effect as that of the first embodiment is obtained. Can be

In both of the above embodiments, the gain set by the gain switching circuit 8 is increased or decreased to simplify control.
Was so adjusted by correcting the phase may be adjusted multistage or continuously corrected and in accordance with the difference between the reproduction level and the reference level of the tracking pilot signal S _4.

Further, the unit correction amount at the time of performing the correction by performing the correction in two or multiple stages may be arbitrarily set according to the circuit conditions and the like.

Various VTs for performing ATF head tracking using a tracking pilot signal
It is needless to say that the present invention can be applied to R, and in this case, the signal on the low frequency side only needs to include at least the tracking pilot signal.

[0052]

Since the present invention is configured as described above, it has the following effects. First, in the case of the video tape recorder according to the first aspect, the set gain of the gain switching circuit 8 is reset to the initial gain by the adjustment level initializing means every time the magnetic tape 15 to be recorded is replaced. by means, recording current S including signal S ₅ of the amplified in initial gain low frequency band
_{After 7} is recorded on the magnetic tape 15 for a certain period of time, the tape 15 is rewound in a reproduction state.

At this time, the tracking pilot signal S of the tape reproduction output obtained by rewinding the reproduction state is used.
₄ levels magnitude varies in accordance with the recording characteristics of the magnetic tape 15 to record, setting the gain switching circuit 8 in accordance with the difference between the tape output of the tracking pilot signal S ₄ levels and the reference level by the gain control means The gain is adjusted.

[0054] Therefore, without performing a selection operation of the conventional tape position, every time the magnetic tape 15 to be recorded are exchanged, amplification level of the signal S ₅ lower frequency is variably adjusted recording current condition is used The conditions optimal for the recording characteristics of the magnetic tape 15 are automatically set, and the operability and recording performance are significantly improved.

Further, in the case of the video tape recorder according to the second aspect, immediately after the power of the video tape recorder is turned on or when the mode transition to the recording pause occurs due to the recording stop operation, the adjustment level is initialized before the transition to the recording pause. By means, the set gain of the gain switching circuit 8 is reset to the initial gain.

The operation mode control means further controls the recording current S including the low-frequency side signal S ₅ amplified by the initial gain.
_{After 7} is recorded on the magnetic tape 15 for a certain period of time, the tape 15 is rewound in a reproducing state, and after this rewind, the recording pause is controlled.

Then, the tracking pilot signal S ₄ of the tape reproduction output obtained by rewinding the reproduction state.
Changes according to the characteristics of the magnetic tape 15 the level of records, set the gain of the gain switching circuit 8 in response to a difference between the tape output of the tracking pilot signal S ₄ of the level and the reference level is adjusted by the gain control means You.

Therefore, each time the operation mode is set to the recording pause, that is, immediately before the next recording, the amplification level of the low-frequency side signal is changed to the recording characteristic of the magnetic tape 15 without performing the conventional tape position selection operation. The recording current condition is automatically set to the optimum condition for the recording characteristics of the magnetic tape 15 to be used, and the operability and the recording performance are remarkably improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video tape recorder according to an embodiment of the present invention.

FIG. 2 is a detailed block diagram of a part of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Operation part 8 Gain switching circuit 9 Recording amplifier 12 Control circuit 14 Cassette loading mechanism 16 Reproduction amplifier 17 ATF / AGC circuit 18 ATF level detection circuit 19 Comparator S ₄ Tracking pilot signal S ₅ Low side signal S ₇ Recording current

Claims (2)

(57) [Claims] 1. A low-frequency signal including a tracking pilot signal is amplified to adjust a level, and a low-frequency signal after a level adjustment and a high-frequency luminance signal are added to form a recording signal. A video tape recorder that converts the recording signal into a recording current and records the recording signal on a magnetic tape; a gain switching circuit that amplifies the low-frequency side signal by a set gain and adjusts a level; Adjustment level initialization means for resetting the set gain to an initial gain, after recording the recording current after the reset of the set gain on a magnetic tape for a certain period, and operation mode control means for rewinding the tape in a reproduction state, The set gain is set according to a difference between a reproduction level of the tracking pilot signal of the tape reproduction output obtained by rewinding the reproduction state and a reference level. A video tape recorder comprising: gain control means for adjusting the adjustment level of the low-frequency side signal according to the recording magnetic tape. 2. A low-frequency signal including a tracking pilot signal is amplified to adjust the level, and the level-adjusted low-frequency signal and high-frequency luminance signal are added to form a recording signal. A video tape recorder that converts the recording signal into a recording current and records the recording signal on a magnetic tape; a gain switching circuit that amplifies the low-frequency side signal by a set gain to adjust a level; and detects a mode transition to a recording pause. Adjusting level initialization means for resetting the set gain to the initial gain, delaying the mode transition to the recording pause, recording the recording current after resetting the set gain on a magnetic tape for a certain period of time, An operation mode control means for controlling the recording pause after rewinding in a playback state; and the tracking of a tape playback output obtained by rewinding in the playback state. A video tape recorder comprising: a gain controller that adjusts the set gain so that the reproduction level of the pilot signal becomes a predetermined level, and variably sets the adjustment level of the low-frequency signal according to the recording magnetic tape.