JP3307001B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing video signals on a magnetic tape.

[0002]

2. Description of the Related Art In recent years, in a magnetic recording / reproducing apparatus, the image quality of not only a normal reproduced image but also a special reproduced image has been increasingly regarded as important. At present, a magnetic recording / reproducing apparatus (hereinafter abbreviated as VTR) using a tape, which is most frequently used, winds a magnetic tape around a rotating drum and places it on a track at an angle with respect to the longitudinal direction of the magnetic tape. Video signal is recorded. (Hereinafter, this method is referred to as a helical scan method.) When performing slow motion reproduction in a helical scan VTR, the inclination of the recorded track does not match the trajectory of the reproducing head, and the time axis shifts or a part of the screen is disturbed. Or the signal-to-noise ratio of the signal is degraded. For this reason, in order to obtain a stable slow-motion image, it is possible to simply repeat the still image reproduction by sending it to a magnetic tape intermittently, and to obtain a complete slow-motion image, attach the head attached to the drum to the drum. It is necessary to move the robot vertically to the rotation direction and control it to accurately trace the recorded track.

FIG. 4 is a block diagram of a reproducing system of a VTR having a conventional mechanism for moving a head. 4, reference numeral 401 denotes a magnetic tape; 402, a magnetic head;
Denotes a preamplifier, 404 denotes a video signal reproducing circuit, 405 denotes a head driving mechanism, 406 denotes a head driving circuit, 407 denotes a level detection circuit, and 408 denotes a control circuit. When performing slow motion reproduction in the VTR of FIG.
01 is reproduced by the magnetic head 402, the output is amplified by the preamplifier 403, and is demodulated to the video signal by the video signal reproducing circuit 404. Also, the preamplifier 40
3 is converted into a signal corresponding to the signal level by the level detection circuit 407, and the magnetic head 402 is controlled by the control circuit 408 so that the output signal of the level detection circuit 407 is maximized.
A control signal for controlling the height of the magnetic head 4 is input to an output signal of the control circuit 408 to the head drive circuit 406.
The magnetic head 402 attached to the drum is moved perpendicularly to the rotation direction of the drum by the head drive mechanism 405 to which 02 is attached. As a result, the magnetic head can be accurately traced on the recorded track.

[0004]

In the above-mentioned conventional magnetic recording / reproducing apparatus, since the head is moved by using a special mechanism, the cost is increased, and it is difficult to increase the reliability. In addition, when slow motion reproduction is performed simply by intermittent feeding, noise appears in the reverse direction. In addition, since the intermittent feed cannot be performed so quickly, the normal playback 5
The limit is about one-half speed.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a magnetic recording / reproducing apparatus which enables slow-motion reproduction at a relatively high speed without using a head using a special movable mechanism.

[0006]

In order to achieve the above object, according to the present invention, there are provided two memories each having a capacity for storing image information for one field, and a memory control for controlling writing and reading of the memory. Means, a reproduced video signal supply means for supplying the reproduced reproduced video signal to the memory, and a portion having a large output of the reproduced video signal determined as a portion having good image quality, and a result of the determination is supplied to the memory control means. And a tape feeding mechanism for feeding a magnetic tape.

[0007]

With the above arrangement, when the tape feeding mechanism continuously feeds the magnetic tape at a speed lower than the speed during normal reproduction in the forward direction or the reverse direction, the memory control means determines a plurality of times based on the determination result of the image quality determining means. By controlling writing to one of the memories so as to form an image of one field by connecting portions having good image quality for tracks, and controlling reading to perform a reading operation to the other of the memories at the same time. Thus, high-quality slow-motion reproduction can be performed without using a head having a special movable mechanism.

[0008]

FIG. 1 is a block diagram of a reproducing system of a VTR according to an embodiment of the present invention. In FIG. 1, 101 is a magnetic tape,
102a, 102b, 102c and 102d are magnetic heads. Magnetic heads 102a, 102b, 102c, 1
FIG. 2 shows the position of 02d on the drum. 103a, 1
03b, 103c, 103d are preamplifiers, 104 is a preamplifier selection circuit, 105 is a video signal demodulation circuit, 106
Is a sync separation circuit, 107 is a write clock and address generation circuit, 108 is a framing detection circuit, 109 is a framing correction circuit, 110 is an image quality discrimination circuit, 111
Is a memory write / read control circuit, 112a, 112
b is a memory, 113 is a memory selection circuit, and 114 is a read clock and address generation circuit.

In the VTR shown in FIG. 1, signals recorded on a magnetic tape 101 are transmitted to magnetic heads 102a, 102b, 1
02c and 102d are reproduced. Each magnetic head 102
The signals reproduced by a, b, c and d are amplified by preamplifiers 103a, 103b, 103c and 103d, respectively. Preamplifiers 103a, 103b, 1
A necessary signal is selected by the preamplifier selection circuit 104 from the output signals of the video signal demodulation circuit 105
Demodulates to a video signal. The synchronization signal is separated from the output signal of the video signal demodulation circuit 105 by the synchronization separation circuit 106, and the write clock and address generation circuit 107 uses the outputs 112 of the synchronization signal separation circuit 106 as the reference to store the memories 112 a and 11.
The write clock and address signal of 2b are generated.

Further, based on the output signal of the synchronization signal separation circuit 106, the framing detection circuit 108 determines whether the video signal is the first field or the second field. When the output of the framing detection circuit 108 malfunctions due to noise and changes while reproducing the same track, the framing correction circuit 109 fixes the framing detection signal until the track being reproduced changes, Alternatively, when the state of the track being reproduced does not change despite the change of the track being reproduced, the framing determination signal is switched in the opposite manner as before. Which track is being reproduced is determined by the head switching signal and the control pulse supplied to the framing correction circuit 109. The output signal of the sync separation circuit 106 is monitored by the image quality discrimination circuit 110, and if the sync signal is disturbed due to dropout or the like and is not normal, control is performed so that the video signal reproduced by the magnetic head at that time is not written in the memory. .

Memory write / read control circuit 111
The control pulse, the phase of the head switching signal, and the image quality determination circuit 110 determine which of the memory 112a and the memory 112b is to be used to write the currently reproduced video signal.
And the output of the framing correction circuit 109. Further, the memory selection circuit 113 is controlled to select which memory outputs a signal. Further, it outputs a control signal for selecting a required signal from the output signals of the preamplifiers 103a, 103b, 103c, and 103d by the preamplifier selection circuit 104. The read clock and address generation circuit 114 generates a clock and an address signal for reading a signal from the memory in synchronization with the reference signal.

[0012] In the VTR of FIG.
By sending the magnetic tape at a speed lower than the double speed, the same track on the tape on which the video signal has been recorded can be reproduced at least twice. A portion having good image quality of the video signal reproduced by the above operation is selected, and the memory write / read control circuit 111 selects the memory 112a or the memory 112b.
The partial image determined to be good in image quality is written into the memory at a position controlled by the write clock and the address generation circuit 107 using one of the two methods.

Since the magnetic tape 101 is fed later than the normal reproduction, the position of the partial image which can be determined to be good in image quality differs for each trace, so that the reproduction starts from a certain track and then moves to the next track. By repeating the above operation for each trace until the images are connected on the memory to form a one-field image, the connected image is used as an output image, and the next one-field image is stored in the other memory. As described above, by outputting the signal while it is connected and configured, slow-motion reproduction without noise can be performed.

FIG. 3 shows an example of a reproduced signal at a quarter speed. As shown in FIG. 3, the large output portions a, b, c, and d in each trace are regarded as the above-described high-quality portions, and one connected image is sequentially formed on the memory. FIG.
In the configuration of the above, the memory 112a is used for the first field, the memory 112b is used for the second field, and when the reproduced signal is the first field, it is written into the memory 112a for the first field, In this case, the data is written in the second field memory 112b. In this way, the framing of the image can be determined only by the information indicating which memory is being read.

In the configuration shown in FIG. 1, even when reproducing a VHS format tape recorded by changing the azimuth of the head for each adjacent track, a pair of heads 102a and 102d having different azimuth angles, and A pair of heads 102b and 102c having different azimuth angles are arranged at positions 180 degrees opposite each other on the drum, and when reproducing the same track, a preamplifier corresponding to a head having the same azimuth as that of the track is used. When the output is selected by the preamplifier selection circuit 104, the number of times the same track is reproduced is increased compared to the case where two heads reproduce the same track at the same tape speed, and a portion with higher image quality can be connected on the memory.

In the configuration shown in FIG. 1, writing is performed in a memory based on a synchronization signal separated from a reproduced signal, and reading is performed from a memory based on a reference signal. Changes can be corrected simultaneously. Also, if the reproduced signal and the reference signal are both the first field, if both are the second field, the reproduced signal is the first field, and if the reference signal is the second field, the reproduced signal is Is the second field and the reference signal is the first field, and the interlace relationship is corrected by changing the read timing of the memory with respect to the reference signal from the memory by a half line.

Although the above embodiment shows a case where a tape on which azimuth recording is performed is reproduced, in a VTR of a format in which recording is performed without adding an azimuth angle, the above operation is performed by two heads and two preamplifiers. It goes without saying that it can be done.

[0018]

According to the structure of the present invention, it is possible to realize a high-quality slow-motion reproduction up to half the speed of normal reproduction in both the forward and reverse directions without using a head having a special movable mechanism. A recording / reproducing device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a playback system of a video recording / playback apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a position of a magnetic head on a drum of the video recording / reproducing apparatus according to one embodiment of the present invention;

FIG. 3 is a diagram showing an example of a reproduced signal according to one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a playback system of a conventional video recording / playback apparatus.

[Explanation of symbols]

 101 magnetic tape 102a, 102b, 102c, 102d magnetic head 103a, 103b, 103c, 103d preamplifier 104 preamplifier selection circuit 105 video signal demodulation circuit 106 synchronization separation circuit 107 write clock and address generation circuit 108 framing detection circuit 109 framing correction circuit 110 image quality Discrimination circuit 111 Memory write / read control circuit 112a, 112b Memory 113 Memory selection circuit 114 Read clock and address generation circuit

Claims (6)

(57) [Claims] 1. A magnetic recording / reproducing apparatus for recording / reproducing a video signal on / from a magnetic tape by disposing a magnetic head at a position facing 180 degrees on a rotating drum, each having a capacity for storing image information for one field. 2
Memory, memory control means for controlling writing and reading of the memory, reproduced video signal supplying means for supplying a reproduced video signal reproduced from the magnetic tape by the magnetic head to the memory, and the reproduced video signal The part with large output is the part with good image quality
In the determination to the image quality determination unit supplies the determination result to the memory control unit, and a said magnetic tape a letter tape feeding mechanism, the tape feeding mechanism is slower than the speed of the normal reproduction the magnetic tape as When continuously sending data in the forward direction or the reverse direction, the memory control unit forms an image of one field by connecting the high-quality portions corresponding to a plurality of head traces based on the determination result of the image quality determination unit. The magnetic recording / reproducing apparatus according to claim 1, wherein the writing is controlled to one of the memories and the reading is controlled to perform the reading operation to the other of the memories. 2. The method according to claim 1, wherein the magnetic head includes two heads having different azimuths and supplies a reproduced video signal when reproducing a magnetic tape recorded with different azimuths for each adjacent track. The means is as described in 2 above.
A magnetic recording / reproducing apparatus characterized in that a reproduced video signal reproduced by a head having the same azimuth as the azimuth of a track to be reproduced among the plurality of heads is supplied to a memory. 3. A framing detecting means according to claim 1, further comprising means for detecting whether the reproduced video signal is a first field or a second field, and supplying the detection result to a memory control means. One of the two memories is a memory for the first field and the other is a memory for the second field. According to the detection result of the framing detection means, the memory control means determines whether the reproduced video signal is in the first field. A magnetic recording / reproducing apparatus, wherein writing is controlled to write to the first field memory, and to write to the second field memory when the reproduced video signal is a second field. 4. The framing detection stage according to claim 3, wherein when the detection result of the framing detection means changes while the same track is reproduced, the framing detection stage continues until the track being reproduced changes. If the detection result is fixed, and the detection result of the framing detection means does not change despite the change of the track being reproduced, the detection result is corrected so that the detection result of the framing detection means is inverted. A magnetic recording / reproducing apparatus comprising framing correction means for supplying a correction result to a memory control means. 5. A synchronizing separation unit according to claim 1, wherein a synchronizing signal is separated from a reproduced video signal and supplied to a memory control unit, and a reference signal is supplied to the memory control unit. A reference signal supply unit for supplying, wherein the memory control unit controls writing based on the synchronization signal separated by the synchronization separation unit and controls reading of the memory based on the reference signal. A magnetic recording / reproducing apparatus characterized in that: 6. The memory control means according to claim 5, wherein the memory control means determines whether the reproduced video signal and the reference signal are both in the first field or both in the second field, When the signal is in the second field or when the reproduced video signal is in the second field and the reference signal is in the first field, the read timing of the memory with respect to the reference signal is changed by a half horizontal synchronization period. A magnetic recording / reproducing apparatus for controlling reading.