JP3985395B2 - Video tape recorder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a video tape recorder compatible with the standard mode and the 3 × mode, and has a problem when performing fast forward / rewind playback (search) of a video tape recorded in the 3 × mode at a constant speed, for example, 27 × speed. The present invention relates to a video tape recorder with a constant speed search function that can be reproduced without causing color disappearance.
[0002]
[Prior art]
In recent years, video tape recorders have increased the speed of fast-forward / rewind time of video tape, and video tape recorders that perform fast-forward and rewind of a 120-minute tape in about 1 minute have been commercialized. Therefore, what is required next is the enhancement of the search function, and one of the means is fast-forward / rewind playback, that is, speeding up the so-called search function.
[0003]
A conventional video tape recorder will be described below.
[0004]
In a conventional 4-head video tape recorder having 2 heads for standard mode and 3 times mode each, the above-mentioned four heads are used for fast-forward / rewind playback in the standard mode according to the head output. In the 3 × mode, fast-forward / rewind playback is performed using only two 3 × -mode heads. FIG. 3 is a block diagram showing the configuration of a conventional video tape recorder head switching system. FIG. 4 shows the positional relationship between the four video heads arranged on the cylinder drum. In FIG. 3, 1 is a standard mode recording / reproducing L'ch head, 2 is a standard mode recording / reproducing R'ch head, 3 is a 3 × mode recording / reproducing Lch head, 4 is a 3 × mode recording / reproducing Rch head, 5 is a cylinder drum equipped with a standard mode recording / reproducing L'ch head 1, a standard mode recording / reproducing R'ch head 2, a 3 × mode recording / reproducing Lch head 3 and a 3 × mode recording / reproducing Rch head 4. Is a signal reproduced by the heads of the standard mode recording / reproducing L'ch head 1, the standard mode recording / reproducing R'ch head 2, the 3 × mode recording / reproducing Lch head 3 and the 3 × mode recording / reproducing Rch head 4. A preamplifier unit that amplifies after passing through the cylinder drum 5, 10 is a standard mode recording / reproducing L'ch head 1, a standard mode recording / reproducing R'ch head 2, 3 times mode recording A head switching unit 101 that switches and outputs a signal that is reproduced by the live Lch head 3 and the Rx head 4 for 3 × mode recording / reproduction and amplified by the preamplifier unit 6 after passing through the cylinder drum 5, 101 is a command from the control unit 11 The first head changeover switch for switching the signal from the signal reproduced by the standard mode recording / reproducing L′ ch head 1 and the standard mode recording / reproducing R′ch head 2 and amplified by the preamplifier unit 6, 102 is the control unit 11. The second head changeover switch 103 for switching the signal from the signal reproduced by the 3 × mode recording / reproducing Lch head 3 and the 3 × mode recording / reproducing Rch head 4 and amplified by the preamplifier unit 6, 103 is a control unit 11 switches the outputs of the first head changeover switch 101 and the second head changeover switch 102 in accordance with a command from the video circuit unit 1. A third head changeover switch that outputs to the first head changeover switch 7, a first detection unit that detects the output of the first head changeover switch 101, and a second detection unit that detects the output of the second head changeover switch 102, 9 is a comparison unit that compares the signals detected by the first detection unit 7 and the second detection unit 8, 11 is a control unit for controlling the head switching unit 10 and the video circuit unit 13, and 12 is a control unit 11 A microcomputer 13 for giving a command to the video circuit unit 13 receives a control from the control unit 11 and converts a signal from the third head changeover switch 103 into a video signal.
[0005]
The operation of the conventional video tape recorder configured as described above will be described below. In normal playback, the first head changeover switch 101 and the second head changeover switch 102 are switched to the respective modes by the control unit 11 according to the rotational position of the cylinder drum 5 to which the four heads are attached. The changeover switch 103 is switched depending on each mode, and the output of reproduction is sent to the video circuit unit 13. During fast forward / rewind playback, the head crosses the tape pattern diagonally, so in the standard mode, four heads are used, the output level is compared by the comparator 9, and the head with higher output is selected by the controller 11. Thus, the first head changeover switch 101 and the second head changeover switch 102 are switched. By doing so, it is possible to improve the image quality at the head switching point.
[0006]
However, in the 3x mode, playback of the 3x mode track with the standard mode head picks up many adjacent and adjacent tracks and degrades the image quality. No reproduction is performed and only the 3 × mode head is used for reproduction.
[0007]
On the other hand, as a technique for improving the image quality of the 3 × mode in recent video tape recorders, the head width of the 3 × mode recording / reproducing head is made larger than the track width of the 3 × mode (19.3 μm) in order to reduce the influence from adjacent tracks. Narrowing of the head is approached.
[0008]
[Problems to be solved by the invention]
However, in the conventional configuration described above, the 3x mode recording / playback Lch head 3 and the 3x mode recording / playback Rch head 4 are used for fast forward / rewind playback of a 3x mode track at a constant speed, for example, 27x speed. When reproducing, the head crosses the track pattern diagonally, so that the number of times the track pattern is skipped increases, the signal component that can be reproduced by the head decreases, and the noise component increases. This tendency is greater as the head width is narrower. If the speed is increased and the noise component is exceeded, the color signal may be out of phase with respect to the burst signal in the video circuit unit 13 and the color may be lost.
[0009]
This will be described with reference to FIG. FIG. 5 is a diagram showing a track trace pattern and an envelope waveform when a 3 × mode track is fast-forwarded and reproduced by a 3 × mode head. The upper part of FIG. 5 shows a pattern in which the head for 3 × mode traces a track when fast-forward reproduction is performed by the conventional technique, and the lower part shows an envelope waveform at that time. As shown in FIG. 5, as the fast-forward speed increases, the output envelope waveform becomes smaller and the noise portion increases, so that the color disappears due to the noise. On the other hand, when the four heads are switched and reproduced as in the standard mode, there is a problem that the image quality is greatly deteriorated because the adjacent and adjacent tracks are picked up when reproducing on the standard mode head side.
[0010]
The present invention solves the above-mentioned conventional problems, and discoloration that becomes a problem when performing fast-forward / rewind playback (search) of a video tape recorded in the 3 × mode at a constant speed, for example, 27 × speed, is performed. An object of the present invention is to provide a video tape recorder with a high-speed search function that can be played back without causing any trouble.
[0011]
[Means for Solving the Problems]
In order to achieve this object, the video tape recorder of the present invention includes an L′ ch head for standard mode recording / playback and an R′ch head for standard mode recording / playback arranged at a position 180 ° opposite to the L′ ch head. A 3 × mode recording / reproducing Lch head with a head width of less than 26 μm arranged as a combination head with the R′ch head and a 3 × mode with a head width of less than 26 μm arranged as a combination head with the L′ ch head Only R'ch head and Rch head when playback speed of fast forward / rewind playback of video tape recorded in 3x mode is above a certain speed, recording / playback Rch head, cylinder drum with 4 heads attached Is used to control the head switching unit so that only the R side track is traced and only the R side track is reproduced. It has a configuration in which a control unit for controlling with respect to the image circuit portion.
[0012]
With this configuration, when performing fast-forward / rewind playback (search) of a video tape recorded in the 3 × mode at a constant speed, for example, 27 × speed, the L′ ch head and the Lch head or R′ch by the head switching device. By using only the head and the Rch head to reproduce and output only one track, a high-speed search can be realized without fading.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, there is provided a standard mode recording / reproduction L′ ch head, a standard mode recording / reproduction R′ch head arranged at a position opposite to the 180 ° thereof, and the R′ch head. A three-times mode recording / reproducing Lch head having a head width of less than 26 μm arranged as a combination head; a three-times mode recording / reproducing Rch head having a head width of less than 26 μm arranged as a combination head with the L′ ch head; The control unit plays back only one track to the head switching unit according to the playback speed of fast forward / rewind playback at a fixed speed or faster in the 3x mode and the cylinder drum with the head attached. In addition, the chroma rotation control is fixed to the video circuit unit and fast forward / rewind playback is performed in the pause playback state. When the video tape recorded in the triple mode is fast-forwarded / rewinded at a constant speed, for example, 27-times speed or higher, the head switching apparatus is provided. By using this, only the track on one side (only L or R) is reproduced, thereby suppressing the occurrence of color disappearance in the video circuit.
[0014]
Hereinafter, embodiments of the video tape recorder of the present invention will be described with reference to the drawings.
[0015]
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a head switching system of a video tape recorder according to Embodiment 1 of the present invention. In FIG. 1, 1 is a standard mode recording / reproducing L'ch head, 2 is a standard mode recording / reproducing R'ch head, 3 is a 3 × mode recording / reproducing Lch head, 4 is a 3 × mode recording / reproducing Rch head, 5 is a cylinder drum equipped with a standard mode recording / reproducing L'ch head 1, a standard mode recording / reproducing R'ch head 2, a 3 × mode recording / reproducing Lch head 3 and a 3 × mode recording / reproducing Rch head 4. Is a signal reproduced by the heads of the standard mode recording / reproducing L'ch head 1, the standard mode recording / reproducing R'ch head 2, the 3 × mode recording / reproducing Lch head 3 and the 3 × mode recording / reproducing Rch head 4. A preamplifier unit that amplifies after passing through the cylinder drum 5, 10 is a standard mode recording / reproducing L'ch head 1, a standard mode recording / reproducing R'ch head 2, 3 times mode recording A head switching unit 101 that switches and outputs a signal that is reproduced by the live Lch head 3 and the Rch head 4 for 3 × mode recording / reproduction and passed through the cylinder drum 5 and then amplified by the preamplifier unit 6, 101 is a command from the control unit 110 The first head changeover switch for switching the signal from the signal reproduced by the standard mode recording / reproducing L′ ch head 1 and the standard mode recording / reproducing R′ch head 2 and amplified by the preamplifier unit 6, 102 is the control unit 110. The second head changeover switch 103 for switching the signal from the signal reproduced by the 3 × mode recording / reproducing Lch head 3 and the 3 × mode recording / reproducing Rch head 4 and amplified by the preamplifier unit 6, 103 is a control unit 110, the outputs of the first head changeover switch 101 and the second head changeover switch 102 are switched according to a command from the video. A third head selector switch to be output to the unit 13, 7 is a first detector for detecting the output of the first head selector switch 101, and 8 is a second detector for detecting the output of the second head selector switch 102. , 9 is a comparison unit for comparing signals detected by the first detection unit 7 and the second detection unit 8, 110 is a control unit for controlling the head switching unit 10 and the video circuit unit 13, and 12 is a control unit. A microcomputer 13 gives a command to the unit 110, and 13 is a video circuit unit that converts a signal from the third head changeover switch 103 into a video signal under the control of the control unit 110.
[0016]
The operation will be described below. In normal reproduction, the first head changeover switch 101 and the second head changeover switch 102 are switched to the respective modes by the control unit 110 according to the rotational position of the cylinder drum 5 to which the four heads are attached. The changeover switch 103 is switched depending on each mode, and the output of reproduction is sent to the video circuit unit 13.
[0017]
In fast forward / rewind playback, the head crosses the tape pattern diagonally, so that in the standard mode, four heads are used, the output level is compared by the comparison unit 9, and the head with higher output is output by the control unit 110. The first head changeover switch 101 and the second head changeover switch 102 are switched so that is selected. By doing so, it is possible to improve the image quality at the head switching point. When fast-forwarding / rewinding the tape recorded in the 3 × mode, as described above, only the standard mode recording / reproducing R ′ ch head 2 and the 3 × mode recording / reproducing Rch head 4 are used as in the normal reproduction. The head switching is performed for each field by the third head switching switch 103.
[0018]
FIG. 2 is a diagram showing a track trace pattern and an envelope waveform when a fast track is reproduced in the triple mode with the standard mode head. The upper part of FIG. 2 shows a pattern in which the standard mode head traces the track when fast-forward playback is performed, and the lower part shows an envelope waveform at that time. Since the head width of the head for the standard mode is larger than that of the head for the triple mode, the trace area is large. As a result, the envelope waveform is increased and the noise portion is also reduced. As a result, even if there are few signal components on the reproduction side with the head for the triple mode, the occurrence of color disappearance can be eliminated by the signal component of the other field .
[0019]
Therefore, the microcomputer 12 senses the speed of fast forward / rewind playback, and when the speed is constant, for example, 27 times faster, the first head changeover switch 101 and the second head changeover switch 102 of the head changeover unit 10 are set. When the controller 110 is operated to reproduce only the R-side track, the first head changeover switch 101 is set to the R ′ side, the second head changeover switch 102 is set to the R side, and the third head changeover is performed for each field. The head selector switch 103 is switched. Similarly, when the L side track is reproduced, the reverse is performed. That is, for each field, by changing the head switching specification that can be switched between the R side and the L side to the pause playback state, for example, one field switched to the R side is played back by the triple mode head 4 and the other side. The field is reproduced by the standard mode head 2 on the R ′ side with the head switching specification set to the pause reproduction state. In this case, since the head width of the standard mode head is more than twice the track width (19.3 μm), even if the standard mode head is tracing the L side track, it is an adjacent track at the same time. The R side track is traced, and the R side track can be reproduced.
[0020]
As described above, according to the present embodiment, in a 4-head video tape recorder using a 3 × mode recording / reproducing head having a head width of less than 26 μm, a 3 × mode track is recorded at a constant speed, for example, 27 × speed or more. In the case of fast forward / rewind playback, the microcomputer 12 senses the playback speed of fast forward / rewind playback and issues a command to the control unit 110. The control unit 110 sends only one track to the head switching unit 10. In order to control the first head changeover switch 101 and the second head changeover switch 102 so as to reproduce, and to fix the chroma processing to either the R side or the L side with respect to the video circuit unit 13 , the chroma rotation is performed. controlled by fixing the, by providing a fast-forward / rewind head switching device to perform the playback pause playback state, triple mode Even when the standard mode head on the fixed side is used for playback, the envelope waveform is increased and the noise portion is reduced as described above. Therefore, the signal component on the side to be played back with the triple mode head is reduced. In addition, it is possible to eliminate color disappearance during fast forward / rewind playback at a certain speed or higher.
[0021]
【The invention's effect】
As described above, the present invention is a four-head video tape recorder that uses a 3 × mode head of less than 26 μm on a tape recorded in 3 × mode. At the same time, according to the playback speed of fast forward / rewind playback, the control unit controls the head switching unit to play only one track, and the chroma rotation control is fixed to the video circuit unit and paused. By providing a head switching device that performs fast forward / rewind playback in the playback state, it is possible to obtain an excellent effect that playback can be performed without fading in fast forward / rewind playback at a certain speed or higher.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a head switching system of a video tape recorder according to Embodiment 1 of the present invention. FIG. 2 shows a track trace pattern when fast-forward playback of a 3 × mode track is performed with a standard mode head. Fig. 3 is a block diagram showing the configuration of a conventional video tape recorder head switching system. Fig. 4 is a diagram showing the arrangement of cylinder drum heads. Fig. 5 is a triple mode track with a triple mode head. Of track trace pattern and envelope waveform when fast-forwarding is played back [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Standard mode L'ch head 2 Standard mode R'ch head 3 Triple mode Lch head 4 Triple mode Rch head 5 Cylinder drum 6 Preamplifier part 7 1st detection part 8 2nd detection part 9 Comparison Unit 10 head switching unit 110 control unit 12 microcomputer 13 video circuit unit

Claims (1)

Arranged as a combination head of an L′ ch head for standard mode recording / reproduction, an R′ch head for standard mode recording / reproduction disposed at a position 180 ° opposite to the L′ ch head, and the R′ch head. 3 × mode recording / reproducing Lch head with a head width of less than 26 μm, a 3 × mode recording / reproducing Rch head with a head width of less than 26 μm arranged as a combined head with the L′ ch head, and a cylinder drum to which the four heads are attached When the playback speed of fast forward / rewind playback of a video tape recorded in the triple mode is higher than a certain speed, only the R'ch head and the Rch head are switched for each field so that only the R side track is traced. video circuit control to fix the orientation of the chroma rotation of reproducing only the R-side track controls the head switching unit Video tape recorder having a control unit which performs relative.

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