JPS5932263A - Gamma correcting device of video signal - Google Patents

Abstract

PURPOSE:To improve the picture quality at the bright part of a video signal, by connecting an inductance element in series with a diode and a resistor suppressing the amplitude of a part close to a white level, in a television receiver. CONSTITUTION:The inductance element 9 representing a high impedance to a high frequency of a video signal is connected in series with the diode 6 and the resistor 7, and the series circuit is connected between the transmission path of the video signal and a bias power supply 8. Since the impedance in parallel with a resistor 4 is increased for higher frequency, the rate of suppression of the amplitude of video signal is decreased as the frequency increases. Thus, the detail of picture at a bright part is displayed clearly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the field of use of a telegraph receiver [m119. This invention relates to a device for suppressing i.

Conventional configuration and its problems In television receivers, as the video signal approaches the white level, the cathode ray tube generates more electricity. The light-emitting surface has the characteristic that when the area increases, the light-emitting surface increases more rapidly.For this reason, when the input video signal approaches the white level to a certain extent, the amplitude of the part close to the white level is suppressed. By doing so, so-called comma correction is performed to suppress the occurrence of X-rays.

Figure 1 shows an example of a comma-sleeved IE circuit conventionally used for the purpose of such correction. By adding to 3, it is delayed by a certain amount of time,
It is taken out from both ends of the load resistor 4 and supplied to the subsequent video amplifier circuit from the output terminal 6, and one end of the diode 6 for comma correction is connected to the transmission path of the video signal r'; The other end is connected to a bias power supply of 8V via a series resistor 7. By doing this, when a video signal like that shown in FIG. When it enters a close range, the tie-auto 6 becomes conductive and the resistor 7 is inserted in parallel with the resistor 4, causing the amplitude of the portion close to the white level of the video signal to be suppressed as shown by the broken line a. That will happen. This suppresses the temperature fluctuations in areas close to the own level. FIG. 5 shows the human output characteristics, where the solid line shows the case without corrected sound, and the broken line a shows the case with the above-mentioned correction 11-.

However, with such conventional comma correction means, in areas closer to the white level than a certain level, a comma axis weight of -4> is always applied and suppressed. The disadvantage is that the details in the image part are no longer visible. An analogy is like the wrinkles on a bright face becoming invisible. For this reason, there is a disadvantage that the image loses its depth and becomes dull and blurry.

OBJECTS OF THE INVENTION Therefore, it is an object of the present invention to provide an overall apparatus capable of eliminating such conventional drawbacks and improving image quality in bright areas of a video signal.

Structure of the Invention The present invention includes a diode that is conductive in a region close to the white level of a video signal and suppresses the amplitude of the portion close to the white level, a resistor, and a video signal. The circuit is characterized by connecting a small total inductance element in series with a large impedance for the range component Q'c of the bow, and connecting this target circuit between the video signal transmission path and the bias voltage σ, >. There is.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 2 to 5. In addition, in FIGS. 2 and 3, parts that are the same as those in the prior art are replaced with the same numerals as in FIG. 1, and explanations thereof will be omitted. In this device, an interftance element 9 having a large impedance in the high range of the video signal is connected in series with the diode 1, the diode 6, and the resistor 7, and the series circuit connects the entire video signal transmission path and the bias power supply 8. I'm trying to connect between. As shown in FIG. 3, this bias power supply 8 has a resistor 10 that divides the power supply VCC.
, 11 and a diode 12 for fflA degree compensation.

With this configuration, the diode 6 becomes conductive in the white level side of the predetermined level of the input video signal, and the amplitude corresponding to the FSB close to its own level is suppressed, as in the conventional case. However, in this case, by providing the interftance element 9 in this device, the amplitude of the video signal is・The higher the frequency, the smaller the suppression rate. Therefore,
In the bright areas where the area J'i is large, that is, the frequency is low, the amplitude suppression effect is sufficiently exerted as shown by the broken line, and in areas where the frequency is low, such as wrinkles on the face, the effect of the inductance element 9 is suppressed. As a result, the amplitude is no longer suppressed, and therefore, it is output with sufficient amplitude as shown by the two-dot chain line C in Figures 4 and 5, so that the details of the image in bright areas can be clearly projected. .

Effects of the Invention As described above, according to the present invention, the effect of suppressing the amplitude of the bright part of the video signal and the ability to clearly display the details in 15 minutes of the bright part of the video signal are achieved. It is possible to realize a practical device that can display both the good and the bad, and the good and the bad.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional video (II bow) comma sleeve 11 device, and FIGS. 2 and 3 are circuit diagrams of a video feed comma supplement II device according to an embodiment of the present invention. Figure 4C
L is a waveform diagram showing its operation, and FIG. 6 is its input/output fI diagram. 1...Input terminal, 4...Resistor, 5...
Output terminal, 6...Diode, 7...
Resistor, 8...Bias power supply, 9...Inductance element, 1Q, 11...Resistance. Name of agent 4 patent attorneys Satoshi Nakao Soj and 1 other person Figure 1 Figure 3 Figure 4 Figure 5 4071

Claims (1)

[Claims] A diode that conducts in a region close to the video signal's own level and suppresses the amplitude of 1b (close to the white level), and a resistor;
A video signal system in which an inductance element that exhibits a large impedance to the high-frequency components of a video signal is connected in series, and this series circuit is connected between the video signal transmission path and a bias power supply. Supplement 11 - Equipment.