JPS62163491A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To extend a frequency characteristic, and to improve the resolution and sharpness by constituting the titled device so that an inclination of a high band cut-off characteristic of a luminance signal which is fetched from a color video signal becomes sharp, and gentle, at the time of a large signal and at the time of a small signal, respectively. CONSTITUTION:In a magnetic recording and reproducing device for bringing a chrominance signal and a luminance signal to a frequency separation from a color video signal, and thereafter, bringing the chrominance signal to a low band conversion, and bringing the luminance signal to a frequency modulation and recording it, an LPF which is used when fetching only the luminance signal from an image input signal is constituted as mentioned below. It is constituted so that an LPF 1 is connected in two stages, a small signal cutting circuit 2 is connected to the second stage, and it is operated as two stages of the LPF in case of a large signal, and operated as one stage of the LPF in case of a small signal. In this way, in case a luminance signal level is small, a restriction of a luminance signal band by the LPF is relieved and it is extended in the high band direction, by which a frequency characteristic can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing color video signals including carrier color signals.

Conventional technology The spectrum of the NTSC system with color signals inserted is configured as shown in Figure 5.The band of the luminance signal is from DC to about 4.2 MH2, and the signal energy of this is DC. It is not uniformly distributed in the range from 4.2 MHz to 4.2 MHz, but most of the time there is a part where no energy exists, and if we decide the carrier wave of the color signal so that the color signal is inserted in that part, The energy component of the color signal is an odd multiple of the horizontal scanning frequency A, and the energy component of the color signal is included between the luminance signals and is synthesized without interference with the luminance signals. When recording this NTSC signal, the configuration of an ordinary magnetic recording/reproducing device (hereinafter referred to as "/TR") is as shown in Figure 4, and the video input signal is passed through a low-pass filter (hereinafter referred to as LPF). 4.5MHz through 3)
The audio carrier wave and the 3.58 MHz carrier color signal component are attenuated, and only the luminance signal is extracted and subjected to FM modulation.

Similarly, a band pass filter (hereinafter referred to as BPF) 7
Only the carrier color signal (approximately 3.58 MH2) is taken out through the recording processing circuit 8, where it is mixed with the FM-modulated luminance signal again, amplified for recording, and sent to the head 10.

At this time, the frequency spectrum of the luminance signal extracted from the color video signal by the LPF 3 is shown in FIG. 6, and the frequency spectrum of the color signal extracted by the BPF 7 is shown in FIG.

Problems to be Solved by the Invention When extracting only the luminance signal as described above, LPF3
Therefore, the band is limited to the one shown in FIG. This is a means to prevent the sidebands of the FM modulated luminance signal from affecting the low frequency converted chrominance signal band when the luminance signal is FM modulated, but this mainly applies to the luminance signal level. When the luminance signal level is large, it affects the color signal and is very effective in preventing beat interference in the reproduced picture, cross color interference, etc. However, when the luminance signal level is small, the color signal is hardly affected, so this method is used. This had the opposite effect, causing problems such as the frequency response not being extended, the resolution being poor, and the screen not being sharp enough.

In view of the above-mentioned problems, the present invention makes it possible to extend the frequency characteristics by relaxing the restriction on the luminance signal band by LPF and extending it toward the higher frequencies when the luminance signal level is small, thereby increasing the resolution and sharpness. The present invention provides a magnetic recording/reproducing device configured to do the following.

Means for Solving the Problems In order to solve the above problems, the magnetic recording and reproducing apparatus of the present invention uses a frequency separation means to frequency separate the carrier color signal and the luminance signal from the color video signal, and then separates the carrier color signal from the carrier color signal using a frequency separation means. A magnetic recording and reproducing device that low frequency converts a signal and frequency-modulates the luminance signal to record it, and in the means for separating the luminance signal from the color video signal, the characteristics of the luminance signal separating means are changed according to the luminance signal level. It has the following configuration.

Effects of the Invention With the above configuration, the present invention provides means for separating a luminance signal from a color video signal during recording, and by changing its characteristics depending on the luminance signal level, the frequency characteristics are broadened during playback, improving resolution and sharpness. This will result in better images.

Embodiment Hereinafter, an embodiment of the magnetic recording/reproducing apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of an LPF used when extracting only a luminance signal from a video input signal of a magnetic recording/reproducing apparatus (hereinafter referred to as VTR) of the present invention. In Fig. 1, 1 is an LPF with a normal OR configuration, and 2 is a small signal cut circuit.In total, two stages of LPF1 are connected, and a small signal cut circuit is connected to the second stage. functions as two stages of I and PF, and in the case of a small signal, functions as one stage of LPF. When a luminance signal is extracted using this LPF, the frequency characteristic will be as shown in FIG. 2. When the brightness signal level is high, the cutoff characteristic is -12 (dB10Ct), b is medium, and the cutoff characteristic is -9 (dBloct), and c.
When is small, the blocking characteristic is -6 (dBloct). Conventionally, whether it was a large signal or a small signal, it was only possible to extract up to a band of about a, but the LPF shown in Figure 1
By passing the signal through, it is possible to improve the ability to output higher frequencies as the signal level decreases.

Fig. 3 is a diagram describing the influence on the color signal after FM modulating the luminance signal, and a, b, and c in Fig. 3 are the luminance signals in the diagrams z, b, and c in Fig. 2. FIG. 3 is a frequency spectrum diagram obtained by mixing after FM modulation or low frequency conversion. a is the luminance signal band FM-modulated through the conventional LPF, and the lower side wave band of the FM-modulated luminance signal is prevented from affecting the low-frequency conversion color signal. However, when the luminance signal level is a medium or small signal, even if it extends to the high range as shown in Figure 2, c, the lower side band of the FM modulated luminance signal is lower, as shown in Figure 3, c. It does not significantly affect the converted color signal. Furthermore, here, an LPF with an OR configuration is described as a means for extracting a luminance signal from a color signal, but the configuration is not limited as long as the same effect can be obtained. For example, a similar effect can be obtained using a digital filter. Further, although it is described as being used only in a recording system, it may also be used in a reproducing system.

Note that in the above embodiments, the filter characteristics are changed depending on the luminance signal level, but it is also possible to change the filter characteristics depending on the amount of high-frequency components of the brightness signal.

Effects of the Invention As described above, according to the present invention, the brightness signal level of a color video signal is changed during recording on a VTR, and the slope of the high frequency cut-off characteristic of the brightness signal extracted from the color video signal is made steep when a large signal is used, and when a small signal is recorded. By making it gentle at traffic lights, F
The luminance signal band after M modulation does not interfere with the low frequency conversion color signal, and the frequency characteristics during reproduction can be expanded, resolution and sharpness can be improved, and better images can be obtained. Become.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the LPF used in the magnetic recording/reproducing device of the present invention, and Fig. 2 is a circuit diagram showing a case where a luminance signal is extracted from a color video signal according to the luminance signal level in the embodiment of the present invention. The frequency spectrum diagram of Figure 3 is the frequency spectrum diagram of Figure 2.
Figure 4 is a block diagram of the recording circuit system for color video input signals in a conventional VTR; Figure 5 is a frequency spectrum diagram of the NTSC system for color video signals; Fig. 6 is a frequency spectrum diagram of a luminance signal extracted from a color video input signal by the low-pass filter shown in Fig. 4, and Fig. 7 is a frequency spectrum diagram of a luminance signal extracted from a color video signal by the band-pass filter shown in Fig. 4. FIG. 3 is a frequency spectrum diagram of a color signal. 1...OR configuration LPF, 2...Small signal cut circuit, 3...Low pass filter, 4
...Emphasis, 5...FM modulation,
6... High-pass filter, 7... Band-pass filter, 8... Carrier color signal recording processing circuit, 9... Recording amplification, 1o・・・・・・Head ○ Name of agent Patent attorney Toshio Nakao and 1 other person 1st
figure! Fig. 2 → f YuJ Fig. 3 → J → J Fig. 5 Fig. 7 (r-tHz) J, 6B (FjH・, -j

Claims (3)

[Claims] (1) It has a frequency separation means that frequency-separates the carrier color signal and the luminance signal from the color video signal, performs low frequency conversion on the carrier color signal, frequency modulates the luminance signal and records it, and separates the luminance signal from the color video signal. 1. A magnetic recording and reproducing apparatus, wherein the separating means controls the characteristics of the luminance signal separating means according to the luminance signal level. (2) The frequency separation means is characterized by being equipped with a low-pass filter that makes the slope of the cutoff characteristic steep when the brightness signal level is high, and makes the slope of the cutoff characteristic gentle when the brightness signal level is low. A magnetic recording/reproducing device according to claim 1. (3) In the frequency separation means, a low-pass filter is used that makes the slope of the cut-off characteristic steep when the brightness signal has many high-frequency components, and makes the slope of the cut-off characteristic gentle when the brightness signal has few high-frequency components. 2. A magnetic recording and reproducing apparatus according to claim 1, further comprising: a magnetic recording and reproducing apparatus;