JPH0385077A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve S/N by converting a reproduced video signal into a voltage fluctuation corresponding to the contrast fluctuation of picture quality, mixing the voltage fluctuation to a picture quality adjustment setting voltage to control the picture quality corresponding to the fluctuation of the contrast in the picture quality. CONSTITUTION:A reproduced video signal 3 is inputted to a clamp circuit 4 and set to a voltage V0 over 0V with a SYNC chip and amplified to 2Vpp by a DC amplifier 5 and integrated by a resistor 6 and a capacitor 7. Then a horizontal synchronizing signal and a change in the horizontal period signal are eliminated and converted into a DC voltage fluctuation representing the lightness during one vertical period. Then the result is mixed to a DC voltage set via an inverting amplifier 8, a buffer amplifier 9, a resistor 10 and a picture quality variable resistor 2 and inputted to a terminal of a luminance processing IC 1. Then the bright part is used as a picture with a high sharpness and the voltage is nearly constant for the dark part and the S/N is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device, and particularly to a home VTR.
The frequency characteristics (hereinafter referred to as
This relates to a device that allows variable control of the F-Spec.

[Conventional technology]

FIG. 2 is a circuit diagram of an image quality control circuit of a conventional magnetic recording/reproducing apparatus. In the figure, 1 is a luminance signal processing circuit (ICL2 is a variable resistor for adjusting image quality).

Next, the operation will be explained.

When a user wants to control sharpness, which is an F characteristic of image quality, in the reproduction of a conventional magnetic recording/reproducing device (hereinafter abbreviated as VTR), the input DC of the terminal of the luminance signal processing ICI is generally used as shown in Fig. 2. The voltage is adjusted via an image quality adjustment variable resistor 2.

That is, the DC voltage at the terminal was varied to the image quality adjustment position set by the user. In the past, F-special was uniformly varied to sharpen the image quality, regardless of the brightness or darkness of the screen. Therefore, the S/N feeling in dark areas was poor. That is, FIG. 3(a),
As shown in (b), if the same F special processing is performed regardless of the brightness or darkness of the screen, the 100
1 RE ((Institute of Radio
Assuming that the noise voltage is 21 RE for a bright screen of 11 RE = 0°714 V, the S/N in this case is 201 og (2/100) = -34 dB. there were.

On the other hand, even for a dark screen with 10IRE as shown in Figure (b), the noise voltage is 2IRE, and the S/N is 201og (2/10) = 14 dB, so the S/N ratio of noise on a dark screen is poor. . In this way, the APL (Average
If F special processing is performed without responding to changes in brightness and darkness of Picture Level), the S/
N deteriorates.

[Problem to be solved by the invention]

Since the conventional VTR is configured as described above, the playback by the VTR requires F-special processing of the video signal regardless of the brightness level of the screen, that is, the brightness/darkness change of the APL, even in bright and dark screens. Because this was done uniformly, the S/N sensitivity in dark areas deteriorated and the S/N in bright areas deteriorated.
/N feeling.

This invention has been made to solve the above-mentioned problems, and provides a magnetic recording and reproducing device that can vary the processing of the F characteristic of a video signal in accordance with the brightness change of the APL of the reproduced signal. The purpose is to

[Means to solve the problem]

The magnetic recording and reproducing apparatus according to the present invention converts a reproduced video signal into voltage fluctuations corresponding to brightness and darkness fluctuations in image quality, and mixes the voltage fluctuations into an image quality adjustment setting voltage.

[Effect]

In this invention, the reproduced video signal is converted into a voltage fluctuation corresponding to the brightness/darkness fluctuation of the image quality, and the voltage fluctuation is mixed with the image quality adjustment setting voltage. Make bright areas sharper,
Image quality can be controlled in dark areas so as not to degrade the S/N sense.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a circuit diagram of an image quality control circuit of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, and in the figure, 1 and 2 are the same as the conventional one.

3 is a video signal, 4 is a clamp circuit, 5 is a DC amplifier,
6 is a resistor, 7 is a capacitor, 8 is an inverting amplifier, 9 is a buffer amplifier, and 10 is a resistor.

Next, the operation will be explained.

The video signal 3 is input to a clamp circuit 4, and is shown in FIG.
), the 5YNC chip is set to have a voltage Vo that is higher than Ov, and after being amplified to 2Vpp (at 100 IRE) by the DC amplifier 5, the resistor 6
The signal is integrated by the capacitor 7, and the horizontal synchronization signal and the change in the signal during the horizontal period are removed as shown in Fig. 4 (mountain), and -
The change in brightness in the vertical period is converted into a DC voltage fluctuation, which is mixed with the DC voltage set through the image quality variable resistor 2 via an inverting amplifier 8, a buffer amplifier 9, and a resistor 10, and is applied to the terminal of the brightness processing ICI. is input.

As shown in FIG. 5, the DC! If the C voltage level is the level of the dot-dashed line 11, then 1
The DC voltage variation of the brightness change in the vertical period is mixed into the DC voltage level, and the voltage to the terminals of the brightness processing ICI becomes like the solid line 12. As can be seen from this voltage curve, F-special processing is performed depending on the steepness or steepness of the curve, and bright areas produce images with high clarity, while dark areas have a nearly constant curve, suppressing F-special, and S/N. The feeling is improved.

〔Effect of the invention〕

As described above, according to the present invention, the reproduced video signal is converted into voltage fluctuations corresponding to the brightness/darkness fluctuations of the image quality, the voltage fluctuations are mixed with the image quality adjustment setting voltage, and the image quality is adjusted in response to the brightness/darkness fluctuations of the screen. Since it is controlled, it is possible to suppress F special processing in dark areas and prevent S/N deterioration.
On the other hand, bright parts have the effect of being able to produce images with high clarity.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an image quality control circuit of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a circuit diagram of an image quality control circuit of a conventional magnetic recording/reproducing apparatus, and FIG.
Diagram showing video signal of S/N ratio depending on brightness and darkness of PL, 4th
The figure shows a clamp waveform of a video signal and its integral waveform, and FIG. 5 shows a mixed voltage for image quality control according to the present invention. 1 is a brightness processing circuit (IC), 2 is an image quality variable resistor, 3 is a video signal, 4 is a clamp circuit, 5 is a DC amplifier, 6 is a resistor, 7 is a capacitor, 8 is an inverting amplifier, 9 is a buffer amplifier, IO is A resistor, 11 is a set DC voltage level, and 12 is a terminal voltage of the brightness processing ICI. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a magnetic recording and reproducing device that has a brightness processing circuit that controls frequency characteristics based on an image quality adjustment voltage set via a variable resistor for image quality adjustment, the reproduced video signal is converted into voltage fluctuations that correspond to brightness and darkness fluctuations in image quality. A magnetic recording/reproducing apparatus comprising: means for mixing the voltage fluctuation with the image quality adjustment setting voltage and inputting the mixed output to the brightness processing circuit.