JPH0533585B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a contour compensation circuit that performs contour compensation, and its purpose is to improve image quality.

Configuration of conventional example and its problems Conventionally, the contour compensation circuit has the following configuration as shown in Fig. 1.
Differentiating circuit 2 converts the video signal applied from input terminal 1
A first signal differentiated by , and a second signal obtained by differentiating a signal obtained by delaying the video signal by a delay circuit 3 including inctance etc. by another differentiating circuit 4 are added to the video signal delayed by the delay circuit 3. It was taken out from output terminal 5. The contour compensation characteristics are determined by the frequency characteristics of the contour compensation circuit. In the conventional circuit, when the contour compensation is minimized, the frequency characteristics are as shown in FIG. 2, and the screen lacks softness. Further, in order to make the screen soft, many parts are required in the delay circuit, and since it is not possible to insert an inductance in a semiconductor integrated circuit, there is an inconvenience that two input pins are required.

Purpose of the Invention The present invention has been made in order to eliminate the above-mentioned disadvantages, and provides a contour compensation circuit that can easily lower the frequency characteristics of a contour compensation circuit and that can be easily configured even in a semiconductor integrated circuit. It provides a circuit.

Configuration of the Invention The present invention has a configuration in which a first signal obtained by differentiating a video signal and a second signal obtained by integrating the video signal and differentiating the integrated signal are added to the integrated video signal. This is a contour compensation circuit, and according to this circuit, the frequency characteristics can be changed depending on the amount of integration of the video signal.

DESCRIPTION OF THE EMBODIMENT FIG. 3 shows a block diagram of an embodiment according to the present invention. The difference from the conventional example shown in FIG. 1 is that differentiation is performed through a delay circuit 3 or an integration circuit 6.

FIG. 4 shows a circuit diagram of a specific embodiment of the contour compensation circuit.

In the figure, 7 is a power supply terminal, 8 is a video input terminal, 9 and 10 are each a contour compensation control terminal, 12 is a DC voltage power supply, 11 and 13 are each a DC voltage application terminal, 14, 25, and 32 are emitters. Ivy follower transistors, 15, 33, 35 are amplifying transistors, 16 are integrating resistors, 17, 34, 3
6, 38, 40 are emitter resistors, 18 is an integration capacitor, 19, 20, 21, 22, 28, 29 are differential amplification transistors, 23, 24, 42 are load resistances, 26, 31 are for differentiation Capacitors 27 and 30 are differentiating resistors, 37 and 39 are current source transistors, and 41 is a video output terminal.

Next, the operation will be explained.

The video signal input to the terminal 8 passes through the emitter follower transistor 14, one enters the base of the amplification transistor 15, is amplified by the ratio of the resistor 42 and the resistor 17, and is sent to the emitter follower transistor 25. A signal differentiated by the time constant of the capacitor 26 and the resistor 27 enters the base of one transistor 28 of the differential pair. The other is resistor 16
It is integrated with the time constant of the capacitor 18 and enters the amplification transistors 33 and 35. The signal entering the transistor 35 is amplified by the ratio of the resistor 36 and the resistor 24, enters the emitter follower transistor 32, and is differentiated by the time constant of the capacitor 31 and the resistor 30.
It enters the other transistor 29 of the differential pair. The signals input to both transistors 28 and 29 of the differential pair are added together and output to the collector of the transistor 28, passed through the contour compensation control transistor 20, applied to the transistor 33, and divided between the resistors 23 and 34. The amplified signal is added to
It is output to terminal 41. The frequency characteristics of contour compensation are as shown in Figure 5, and are mainly caused by resistance 16 and capacitance 18.
It is determined by the constant of integration.

Effects of the Invention As explained above using the embodiments, according to the present invention, the frequency characteristics of contour compensation can be changed by the time constant of integration, and a delay circuit such as an inductance is not required. , it is easy to integrate semiconductors, can be configured with one pin input, and the screen can be made soft.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional contour compensation circuit, Figure 2 is a frequency characteristic diagram when the conventional contour compensation is not performed,
FIG. 3 is a block diagram of an embodiment of the present invention, FIG. 4 is a specific circuit diagram of a contour compensation circuit, and FIG. 5 is a frequency characteristic diagram when contour compensation is not performed according to the present invention. 1...Video input terminal, 2 and 4...Differential circuit, 3
...Delay circuit, 5...Output terminal, 6...Integrator circuit.

Claims (1)

[Claims] 1. A contour compensation circuit comprising a circuit configuration for adding a first signal obtained by differentiating a video signal and a second signal obtained by integrating the video signal and differentiating the integrated signal to the integrated video signal.