JPS63122002A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To apply recording and reproduction with a rotary erasure head without limiting a band of a video signal and an exclusive rotary head by using an erasure current supplied to the rotary erasure head as a bias current and superimposing a signal on the erasure current. CONSTITUTION:After an audio signal inputted from input terminals 1, 2 is subjected to frequency modulation, 1st and 2nd FM audio signals are extracted and subjected to frequency multiplex by a mixing circuit 7. The amplitude of the erasure current is changed according to a control circuit 10 and supplied to a superimposing circuit 11. Said signal from the circuit 7 is superimposed on the erasure current by the circuit 11 and amplified, the erasure current is used as the bias current by the rotary erasure head 13 to magnetize a magnetic tape up to the depth and recorded. On the other hand, the video signal is recorded on a track with an FM audio signal recorded thereupon by the magnetic head for the video signal. The video signal is recorded only on the upper layer of the tape. The signal from the head 13 is amplified at reproduction, separated into the 1st and 2nd signals and reproduced into the audio signal and outputted to output terminals 19, 20.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus capable of recording and reproducing audio signals and other information in addition to video signals.

Conventional technologyMagnetic recording and reproducing equipment for recording and reproducing video and audio signals (
When recording and reproducing high-quality audio signals with a VTR (hereinafter referred to as a VTR), the audio signals are frequency modulated and recorded and reproduced onto a magnetic tape using a rotating magnetic head. As a recording and reproducing method for frequency modulated audio signals (hereinafter referred to as FM audio signals), frequency modulated video signals and FM
There are two known methods: one in which audio signals are recorded and reproduced by frequency division multiplexing, and the other in which a rotating magnetic head dedicated to recording and reproducing FM audio signals is provided to record and reproduce the FM audio signals deep into the magnetic tape. .

FIG. 2 shows the frequency spectrum of the recording current in the frequency division multiplexing method, and FIG. 3 shows the frequency spectrum of the recording current in the deep recording method.

The operation of a conventional VTR that records and reproduces two-channel FM audio signals will be described below. With frequency division multiplexing, the video signal during recording is separated into an a-degree signal and a color signal using a low-pass filter and a band-pass filter, the brightness signal is frequency modulated (FM brightness signal), and the color signal is approximately 629K.
The frequency is converted to a low frequency band of Hz (low frequency converted color signal), and the low frequency spectral components of the FM luminance signal and the high frequency range of the low frequency converted color signal are removed by a bypass filter and a low pass filter, respectively. Create a frequency domain to insert the audio signal. On the other hand, the 2
The audio signals of each channel are approximately 1.38MHz
, is frequency modulated into an FM audio signal using approximately 1.88 MHz as an FM carrier, and after limiting the band with a bandpass filter, is multiplexed into the frequency domain of the above-mentioned FM audio insertion.

Figure 2 shows these spectral relationships. In Figure 2, a is the FM carrier of the luminance signal, b is the subcarrier of the low frequency converted color signal, and C is the FM carrier of the first audio channel.
M audio signal, d is the FM audio signal of the second audio channel. As shown in FIG. 2, the frequency-multiplexed signal is recorded on a magnetic tape by a rotating magnetic head via a recording amplifier. During playback, the playback signal from the magnetic head is amplified by a playback amplifier, and then separated into an FM luminance signal by a bypass filter, a low-pass conversion color signal by a low-pass filter, and an FM audio signal by a bandpass filter, and the playback signals are processed. Later, the original video signal and two-channel audio signal were obtained.

In addition, the deep recording type is equipped with a dedicated magnetic head for FM audio that has an azimuth angle different from that of the magnetic head for video signals, and the FM carrier is used as a crossover between the spectrum of the FM luminance signal and the low-frequency conversion color signal. Near the point (the first audio channel is approximately 1.3MHz, the second
channel is set to approximately 1.7MHz), and the F
The FIFM audio signal is recorded into the deep layer of the magnetic tape using a dedicated head for M audio, and the video signal (a multiplexed signal of the FM luminance signal and low-frequency conversion color signal) is transferred from above the recorded FM audio signal to the magnetic tape. recorded. FIG. 3 is a diagram showing the frequency spectrum of the recording signal mentioned above.
■) represents the spectrum of the FM audio signal, and a
-d indicates the same as in FIG.

During playback, since the azimuth angles of the video signal head and the FM audio head are different, the crosstalk between the video signal and FM audio signal is reduced by azimuth loss, and the playback signal from the video signal head is processed for playback. The original two-channel audio signal is obtained by processing the original video signal and the reproduction signal from the FM audio head.

By the way, VTRs with editing functions generally have a rotating erasing head, and the conventional rotating erasing head is used to erase video signals recorded on a magnetic tape track by track for editing. It is used as a special head. The erasing frequency of the erasing current supplied to the rotating erasing head is approximately 4 MHz, the gap length of the rotating erasing head is set to be thicker than the gap length of the video signal head, and the erasing frequency itself is approximately 4 MHz. Prevents being recorded.

Problems to be Solved by the Invention However, in frequency division multiplexing VTRs, the second
As shown in the figure, since the luminance signal, one color signal, and the audio signal are frequency-multiplexed and recorded and reproduced using the same head, there is a problem in that cross-modulation occurs between the video signal and the audio signal, resulting in deterioration of the reproduced image quality. Furthermore, since the frequency band of the FM luminance signal is limited by the FM audio signal, the video band of the reproduced video signal is limited, making it impossible to achieve high image quality.

Further, a VTR equipped with a dedicated head for FM audio requires a dedicated rotary head and a rotary transformer, resulting in an increase in cost.

In view of the above, the present invention makes effective use of a rotating erase head to record frequency-modulated audio signals and other information without providing a dedicated rotating head and without limiting the band of video signals. An object of the present invention is to provide a magnetic recording and reproducing device that can reproduce data.

Means for Solving the Problems The present invention is a magnetic recording/reproducing device equipped with a rotating erasing head, in which an erasing current supplied to the rotating erasing head is used as a bias current, and a signal is superimposed on the erasing current, so that the rotating erasing head This is a magnetic recording and reproducing device equipped with means for recording and reproducing.

Further, the present invention is a magnetic recording/reproducing apparatus further provided with means for setting an azimuth angle between the rotating erasing heads and varying the erasing current supplied to the rotating erasing heads when erasing by the rotating erasing heads is not required.

Effect of the Invention The present invention has the above-mentioned configuration, whereby the signal superimposed on the erasing current is recorded into the deep part of the magnetic tape by the rotating erasing head without adding a dedicated magnetic head or rotary transformer. At this time, since the erasing current becomes a bias current for the recording signal, the erasing function of the rotary erasing head is not impaired. Furthermore, since recording and reproduction is performed by a rotary erasing head that is a separate head from the rotary head for video signals, the band of video signals is not restricted more than necessary. moreover,
By providing an azimuth angle between the rotating erase heads, crosstalk from adjacent tracks during reproduction can be reduced. Furthermore, if erasing with a rotating erasing head is not required,
Since the erase current can be varied to reduce the shear bias current, interference with the reproduced video signal can be reduced, and the rotary erase head can be set to optimize the characteristics of the recorded and reproduced signal, and power consumption can be reduced. It also reduces

Embodiment FIG. 1 is a block diagram of the main parts of a magnetic recording and reproducing apparatus in an embodiment of the present invention.

The two channels of audio signals inputted from the input terminals 1.2 are each subjected to recording processing and frequency modulation in the modulation circuits 3.4, and are filtered through the bandpass filters 5.6 to the first and second channels. Second F
M audio signals are extracted and frequency multiplexed by a mixing circuit 7. On the other hand, the erasing current outputted from the erasing current generating circuit 8 is supplied to the superimposing circuit 11 after changing the amplitude of the current in accordance with the control signal 10 in the variable circuit 9 . The control signal 1o is a signal that is "no error" during editing and "low level" at other times.The two-channel FM audio signal frequency-multiplexed by the mixing circuit 7 is subjected to an erasing current in the superimposing circuit 11. The erase current is superimposed on the current, the power is amplified by the amplifier 12, and the erase current is used as a bias current to record on the magnetic tape by the rotating erase head 12.Since the erase current is used as a bias current, the conventional erasing function using the rotating erase head cannot be performed. I can't get used to it.

At this time, the signal frequency of the FM audio signal must be selected depending on the gap length of the magnetic head 13 and the relative speed between the magnetic head 13 and the tape. Furthermore, the signal frequency of the erasing current must be selected to be approximately six times or more the highest frequency of the FM audio signal, and must also be selected at a frequency at which the erasing current itself is not recorded on the magnetic tape. For example, when the gap length of the magnetic head is 4 μm and the relative speed is 7 m/s, the first. The signal frequency of the second FM audio signal is typically selected to be several hundred KHz to IMHz, and the signal frequency of the erase current is typically selected to be approximately 4 to 5 MHz.

Since the gap length of the rotary erase head is large and the signal frequency of the FM audio signal is low, even the deep portion of the magnetic tape is magnetized and recorded by the rotary erase head.

On the other hand, the video signal is transmitted by the video signal magnetic head j9.
The FM audio signal is recorded on the recorded track and track. At this time, since the gap length of the video signal magnetic head is smaller than the gap length of the rotary erasing head and the FM frequency of the video signal is high, only the upper layer of the magnetic tape is magnetized. Therefore, the FM audio signal is recorded in the deep layer of the same track of the magnetic tape, and the video signal is recorded in the upper layer.

During playback, the signal taken out from the rotary erasing head 13VC is amplified by the playback amplifier 14, the first and second playback FM audio signals are separated by bandpass filters 15 and 16, and the two channels are separated by demodulation circuits 17 and 18, respectively. The audio signals are reproduced and output to output terminals 19 and 20. Regarding the video signal, a reproduced video signal can be obtained in the conventional manner using a signal from a magnetic head for video signals. At this time, the azimuth angles of the rotary erasing head and the magnetic head for video signals can be made different, and azimuth loss is utilized to reduce crosstalk.

Also, by providing an azimuth angle between the rotating erase heads, crosstalk from adjacent tracks of the FM audio signal is reduced.

In this way, video signals and FM signals are placed on the same track of magnetic tape.
Since audio signals are recorded, the current value supplied to the rotary erasing head is such that there is no interference with the reproduced video signal, no deterioration of the characteristics of the reproduced audio signal, and the signal on the magnetic tape is completely erased. It must be the optimal value that can be achieved. During editing, in order to completely erase the signals on the magnetic tape with the rotating erase head, the erase current is set to a value that is greater than the saturation magnetic field of the magnetic tape. During other recordings, erasing is performed using the full-width erasing head, so erasing using the rotating erasing head is not necessary. Set it like this. The value at this time is close to the coercive force of the magnetic tape. Since the coercive force of the magnetic tape has a small value as well as the saturation magnetic field, there is little interference with the reproduced video signal during recording other than when editing, and the characteristics of the reproduced audio signal can be made the best. The above-mentioned switching of the current value is performed by the variable circuit 9 according to the control signal 1o.

In this embodiment, all the signals recorded by the rotary erasing head are audio signals, but other information or data signals may be used.

Effects of the Invention As explained above, according to the present invention, the conventional rotary erasing head can eliminate the need to add a magnetic head or rotary transformer exclusively for audio signals, other information, and data signals. without damaging the erasing function or limiting the video signal band.
It can record and reproduce data, reduce crosstalk from adjacent tracks, reduce interference with reproduced video signals, and optimize the characteristics of reproduced audio signals, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the frequency spectrum of the recording current of a conventional magnetic recording/reproducing apparatus, and FIG. 3 is a diagram of another conventional magnetic recording/reproducing apparatus. FIG. 2 is an explanatory diagram of a frequency spectrum of a recording current of a magnetic recording/reproducing device. 3.4...Modulation circuit, 7...Mixing circuit, 8...Erasing current generation circuit, 9...Variable circuit, 10...・Control signal, 11...
Superimposition circuit, 13-...Rotating erasing head, 17,1
8... Demodulation circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure line - (U')

Claims (3)

[Claims] (1) In a magnetic recording and reproducing device equipped with a rotary erasing head having an azimuth angle different from that of a rotary head for recording and reproducing video signals, the erasing current supplied to the rotary erasing head is used as a bias current, and the signal is transferred to the erasing current. What is claimed is: 1. A magnetic recording and reproducing device comprising: means for recording and reproducing information by a rotating erasing head in a manner that is superimposed on the magnetic recording device; (2) The magnetic recording/reproducing apparatus according to claim 1, wherein an azimuth angle is provided between the rotary erasing heads. (3) The magnetic recording and reproducing apparatus according to claim 1, further comprising means for varying the erase current supplied to the rotary erase head when erasing by the rotary erase head is unnecessary.