JPS62123887A - Video signal recorder - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of a recording wavelength by changing signal frequency for low band conversion basing on a signal reproduced by a head that traces on a recording medium separately from a head in recording. CONSTITUTION:When recorded signals in which recording wavelength is not fluctuated are reproduced by ahead which is in contact with a head other than a recording head 5, fluctuation in reproducing wavelength occurs in the reproduced signals. Accordingly, already recorded signals are reproduced by a head selected by a switch 20, and chrominance signals are extracted from the reproduced signals by a filter 19 and made to a continuous signal by a frequency converter 17, then frequency converted by oscillation signals of an oscillator 18 and supplied to a frequency converter 15 through a switch 16. Thereby, low band conversion chrominance signals having variation beforehand to correct variation of wavelength at the time of recording are sent to a head for recording, and chrominance signals free from variation in recording wavelength are recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a video signal recording device.

[Prior Art] Conventionally, this type of device is a video tape recorder (VT).
R), but in recent years, VTRs have been equipped with heads for special playback or long-time recording and playback in addition to the two m semi-recording/playback heads, reflecting the market needs for multi-functionality. More and more VTRs are mounted on drums. Furthermore, in recent years, the diameter of the drum has been reduced to 2/3 of that of the conventional one, four heads are arranged orthogonally on the drum, and a VTR 1 or an erasing head that performs recording and playback using the four heads alternatively is arranged on the drum. There are VTRs that have improved image quality during continuous shots, etc.

Therefore, a VTR having a conventional drum diameter of 273 mm and four heads disposed orthogonally on two drums will be described with reference to FIGS. 3 to 5.

Figure 3 is a diagram showing the arrangement of the heads on the drum and the positional relationship between the tape and the head, Figure 4 is a diagram showing the positional relationship of the heads on the tape, and Figure 5 is a diagram showing color unevenness on the playback screen. It is. In the figure.

1 is a drum, 2 is a tape, 3 is a tape guide member, 4.
5, 6, and 7 are recording heads arranged perpendicularly to each other on this drum 1.

[Problems to be Solved by the Invention] In the above-described apparatus, when the head 5 is currently recording, the direction of rotation of the drum and the direction of tape advancement are indicated by the arrows in FIGS. 3 and 4. show. The head 5 first comes into contact with the tape from position A in FIG. 3 and starts recording. Then, when the head 4 reaches the position A in the figure, the head 4 starts to come into contact with the tape, and the impact when the head 4 comes into contact with the tape causes a relative speed fluctuation between the tape and the head.

Recording wavelength fluctuates. Next, when the head 5 reaches the position shown in the figure, the head 7 starts to come into contact with the tape, so
Similar to the above, fluctuations occur in the recording wavelength.

In this way, when a certain head is recording a certain track, the above-mentioned phenomenon occurs at a position that is divided into three equal parts, and this appears as color unevenness on the playback screen as shown in Figure 5. As can be seen from the cause of this color unevenness, the position where it appears on the screen is fixed by the arrangement of the head on the drum.

As mentioned above, in conventional devices, during recording, a head other than the recording head comes into contact with the tape or separates from the tape, and the impact changes the speed of the drum or tape, causing the recording wavelength to change. There is a problem in that when this recording tape is played back on another deck, fixed color unevenness occurs in the reproduced image.

The present invention was made to solve this problem, and an object of the present invention is to provide a video signal recording device that can eliminate fluctuations in recording wavelength that occur during recording.

[Means for Solving the Problems] A video signal recording device according to the present invention traces the frequency of a signal used for converting a color signal to a low frequency band on a recording medium separately from the recording head. It changes based on the signal reproduced from the head that is playing.

[Operation] According to the above configuration, the variation in the recording wavelength that occurs regardless of the time axis variation of the recording signal is detected by the reproduction signal of the head tracing the recording medium separately from the recording head, By changing the frequency of the signal used for low frequency conversion of the color signal during recording, fluctuations in the E green wavelength are removed.

[Embodiment] FIG. 1 is a schematic block diagram of a recording system of a VTR which is an embodiment of the present invention, and FIG. 2 shows switching signals a,
FIG.

In the figure, 12 is a changeover switch for selecting the recording head;
13 is a luminance signal processing circuit that performs processing such as FM modulation on the luminance signal in the video signal inputted from the terminal 23; 14 is a mixer that mixes the luminance signal and the color signal; and 15 is a converter that converts the color signal to a low frequency signal. A frequency converter 16 converts a reference signal from an automatic phase control (APC) circuit 22 of a well-known recording system or an output signal of a frequency converter 17 to be described later into the frequency converter 1.
5, a frequency converter 17 converts the burst signal into a continuous wave signal and then converts the frequency;
8 is an oscillator, 19 is a filter for extracting a color signal from the output signal of the changeover switch 20, 20 is a switch for selecting a reproduction head, and 21 is a burst gate for extracting a burst signal from the color signal extracted by the filter 19. can be,
Further, the same reference numerals as in FIG. 3 indicate the same or corresponding parts.

In the apparatus configured as described above, first.

At positions other than those where impact occurs due to head contact or detachment, the above-mentioned reference signal is applied to the frequency converter 15 by the switch 16, the color signal is converted to a low frequency signal by the frequency converter 15, and the brightness signal is converted by the mixer 14. The signal is mixed with the signal and recorded by the head selected by the changeover switch 12.

Next, in the area where impact occurs due to head contact and separation,
When a recording signal whose recording wavelength does not fluctuate is reproduced by a head other than recording head 5 that is in contact with the tape (any of heads 4, 6, or 7), the reproduced signal has fluctuations in the reproduction wavelength. arise. Therefore, the already recorded signal is reproduced by the head selected by the switch 20, as will be described later.

A filter 19 extracts a color signal from the reproduced signal.

Then, the burst signal of this color signal is sent to the burst gate 2.
The signal is taken out from 1 and converted into a continuous wave by the 1 frequency converter 17, then frequency-converted using the oscillation signal of the oscillator and applied to the frequency converter 15 via the switch 16.

The frequency converter 15 performs low frequency conversion and sends the color signal, which has a variation in wavelength, to the recording head so as to correct the wavelength variation during recording. and,
Frequency fluctuations during recording are mutually canceled out, and a color signal with no fluctuation in recording wavelength is recorded.

In Fig. 2, a is a 15Hz signal, b is a 30Hz signal, c and d are signals created to be located at the phase where color unevenness occurs in the video signal, and signal e is a signal of these two. OR gate 18
This is the signal taken by

The switching operations of the changeover switches 12 and 20 will be explained in Section 22. First, the changeover switch 12 is used. Head selection is based on the combination of signals a and b (a is H (high) - b is H, a
is H-b, a is L-b, Hla is L-b is L), and the selection is made in the order of 4.5.6.7. Further, when the signal C input to the changeover switch 20 is H, the head selected next in rotation is selected for the head selected by the switch 12, and the signal d input to the changeover switch 20 is H. In this case, it is sufficient to select the head selected one time before the head selected by the switch 8 in rotation.

[Effect of the invention] As explained above, this invention
By changing the frequency of the signal used for low frequency conversion of the reproduced color signal based on the signal reproduced by the head tracing on the recording medium separately from the color signal,
It is now possible to prevent fluctuations in the recording wavelength.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram of a recording system in a VTR which is an embodiment of the present invention, Fig. 2 is a waveform diagram showing the switching signals shown in Fig. 1, and Fig. 3 shows the arrangement of the head on the drum and the tape arrangement. FIG. 4 is a diagram showing the positional relationship between the head and the head, FIG. 4 is a diagram showing the positional relationship of the head on the tape, and FIG. 5 is a diagram for explaining color unevenness on the playback screen. In the figure, 4.5.6.7 is a head, 12 is a changeover switch, 13 is a luminance signal processing circuit, 14 is a mixer, 15.
17 is a frequency converter, 16 is a switch, 20 is a changeover switch, 18 is an oscillator, 19 is a filter, and 21 is a burst gate.

Claims (1)

[Claims] In a video signal recording device, changing the frequency of the signal used to convert the color signal to a low frequency band during recording based on the signal reproduced from a head tracing the recording medium separately from the recording head. A video signal recording device characterized by: