JPH06189161A - Video signal correcting circuit - Google Patents

Abstract

PURPOSE:To make image easy-to-see by applying the correction which is opposite to the frequency characteristic of a video signal processing circuit used for a video equipment such as a television to the output signal of a computer or the like while using the video signal correcting circuit, and inputting the output signal to this video signal processing circuit. CONSTITUTION:This circuit is provided with a negative feedback amplifier 2, the frequency characteristic of a feedback circuit at this amplifier 2 is changed corresponding to the input signal, the frequency characteristic of the amplifier 2 is switched, and the signal is inputted to the video signal processing circuit of the television or the like. As the feedback circuit, the output circuit of the amplifier 2 is branched and successively connected through resistors 4, 5 and 6 to the ground, a feedback voltage is extracted from a gap between the resistors 5 and 6 and inputted to the amplifier 2, and a switcher 7 and plural capacitors 8 and 9 at different values connected to this switcher 7 are provided in parallel with the resistor 5. The capacitor to be parallel with the resistor 5 is selected by switching this switcher 7, and the frequency characteristic of the feedback circuit is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal correction circuit, and more particularly to a correction circuit used for correcting a signal from a computer or the like and inputting it to a video signal input terminal of a television or the like. In recent years, with the development of package media, the opportunities for televisions and the like to be used as terminal devices for various signals have increased.

[0002]

2. Description of the Related Art In conventional video equipment such as televisions,
As shown in FIG. 2B, the high frequency gain of the frequency characteristic of the video signal processing circuit is raised so that the image quality tends to overshoot and undershoot, and the contour of the image is emphasized to improve the resolution. I was trying to do it.

[0003]

Therefore, when a signal from a computer or the like is input to a video device such as a television, the contour of the display signal is emphasized and the screen is glaring, which is difficult to see. INDUSTRIAL APPLICABILITY The present invention uses a video signal correction circuit, applies a correction reverse to the frequency characteristic of a video signal processing circuit used in a video device such as a television, and inputs the video signal processing circuit to make the image easy to see. The purpose is to

[0004]

As shown in FIG. 1, a negative feedback type amplifier 2 is provided and the same amplifier 2 is provided according to an input signal.
The frequency characteristic of the feedback circuit is changed so that the frequency characteristic of the amplifier 2 is switched and input to the video signal processing circuit of a television or the like. The output circuit of the amplifier 2 is branched as the feedback circuit, Connected to the ground via resistors 4, 5, and 6 in that order, and resistors 5 and 6
A feedback voltage is taken out from between the switches and input to the amplifier 2, and a switching device 7 and a plurality of capacitors 8 and 9 having different values connected to the switching device 7 are provided in parallel with the resistor 5 to switch the switching device 7. Thus, a capacitor in parallel with the resistor 5 is selected to change the frequency characteristic of the feedback circuit.

[0005]

According to the present invention having the above-mentioned structure, the capacitor connected in parallel with the resistor 5 is selected by switching the switch 7, and the frequency characteristic of the feedback circuit is changed.
As shown in (A), the frequency characteristic of the amplifier 2 is switched, and the frequency characteristic of a video signal processing circuit used in a video device such as a television is corrected to be reversed,
By inputting it to the video signal processing circuit, the frequency characteristics of the overall video signal processing circuit are lowered as shown in FIG. 2 (C) so that the gain in the high frequency range is lowered to eliminate the image quality that tends to overshoot and undershoot. Therefore, an input signal from a computer or the like can be displayed as an easy-to-see screen without glare.

[0006]

FIG. 1 is an electric circuit block diagram of a video signal correction circuit showing an embodiment of the present invention. Reference numeral 1 is an input terminal, for example, a signal from a computer or the like is input, and the signal is input to the amplifier 2 via the input terminal 1. As the amplifier 2, for example, a non-inverting operational amplifier or the like is used, which amplifies an input signal and outputs it from an output terminal 3 so that it can be input to a video signal input terminal of a television or the like to display a signal on a screen. . The output circuit of the amplifier 2 is provided with a feedback circuit for negative feedback to the input side, and the frequency characteristic of the feedback circuit is switched so that the frequency characteristic of the amplifier 2 can be changed.

As the feedback circuit, the output circuit of the amplifier 2 is branched and connected to the ground via the resistor 4, the resistor 5, and the resistor 6 in this order, and the feedback voltage is applied between the resistor 5 and the resistor 6. By taking out and inputting it to the amplifier 2, a switching device 7 and a plurality of capacitors 8 and 9 having different values connected to the switching terminals of the switching device 7 are provided in parallel with the resistor 5, and by switching the switching device 7, the resistance is changed. The frequency characteristic of the feedback circuit is changed by selecting a capacitor in parallel with the device 5. The values of the resistors 4, 5 and 6, and the capacitors 8 and 9 are selected and determined so that the desired frequency characteristic of the amplifier 2 can be obtained. In the case of the embodiment, the frequency characteristic is switched in three stages. However, the number of switching steps may be increased or decreased. Further, the switching device 7 may be switched manually or may be switched by inputting a switching signal. The video signal correction circuit of the present invention may be used by incorporating it into an output circuit of a computer or the like, or may be incorporated into a video signal input terminal of a television or the like, or may be provided between the two. It may be used as a connector.

FIGS. 2A to 2C are frequency characteristic diagrams for explaining the operation of the video signal correction circuit of the present invention. FIG. 6A is a frequency characteristic diagram of the video signal correction circuit of the present invention,
When the switch 7 in FIG. 1 is switched to, there is no capacitor connected in parallel with the resistor 5 because the terminal is open, and therefore the frequency characteristic is flat, and the frequency characteristic of the overall video signal processing circuit is (B) is shown, and can be used for inputting a normal video signal as in the conventional case. When the switch 7 is switched to, the capacitor 9 connected to the terminal of becomes parallel to the resistor 5, and if a value smaller than the capacitor 8 is used as the capacitor 9, the curve shown in FIG. When the switch 7 is switched to, the capacitor 8 connected to the terminal of becomes a connected state in parallel with the resistor 5,
The curve shown in (A) is obtained, and therefore, the frequency characteristics of the overall video signal processing circuit are such that the gain in the high frequency range is lowered as shown in (C), and the image quality tends to overshoot and undershoot. Therefore, the input signal from a computer or the like can be displayed as a glare-free and easy-to-see screen.

[0009]

As described above, according to the present invention,
An input signal from a computer or the like can be input to a video signal processing circuit of a television by applying a correction opposite to a frequency characteristic of a video signal processing circuit used in a video device of a television or the like. A video signal correction circuit capable of displaying an image that is easy to see can be provided.

[Brief description of drawings]

FIG. 1 is an electric circuit block diagram of a video signal correction circuit showing an embodiment of the present invention.

FIG. 2A to FIG. 2C are frequency characteristic diagrams for explaining the operation of the video signal correction circuit of the present invention.

[Explanation of symbols]

 1 Input Terminal 2 Amplifier 3 Output Terminal 4 Resistor 5 Resistor 6 Resistor 7 Switching Device 8 Capacitor 9 Capacitor

Claims (3)

[Claims] 1. A video signal, comprising: a video signal correction circuit having a variable frequency characteristic, and switching the frequency characteristic of the correction circuit according to an input signal to input the video signal to a video signal processing circuit such as a television. Correction circuit. 2. The video signal correction circuit according to claim 1, wherein the video signal correction circuit comprises a negative feedback type amplifier, and the frequency characteristic of the feedback circuit is changed to switch the frequency characteristic of the correction circuit. circuit. 3. The feedback circuit branches from the output circuit of the correction circuit and is connected to the ground via a first resistor, a second resistor and a third resistor in order, and a second resistor and a third resistor. By extracting a feedback voltage from between the resistors and inputting it to the amplifier, a switching device and a plurality of capacitors having different values connected to the switching device are provided in parallel with the second resistor, and the switching device is switched. 3. The video signal correction circuit according to claim 2, wherein the frequency characteristic of the feedback circuit is changed by selecting a capacitor in parallel with the second resistor.