JPH02249366A - Contour compensation device - Google Patents

Abstract

PURPOSE:To obtain a pattern in response to the natural contrast with a simple circuit by controlling the contour compensation effect of a video image in response to the voltage for contrast adjustment. CONSTITUTION:Speed modulation circuits (VM circuit) 1-7 use a contrast adjustment voltage 30 to cause the contour compensation effect by the VM in response to the contrast adjustment by the user. When the contrast is large, the compensation effect is increased and when the contrast is small, the compensation effect is decreased to make the emphasis of contour on the pattern proper. Thus, a sense of disorder is avoided and an easy to see pattern is always displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a contour compensation device using a velocity modulation circuit in a television receiver.

Conventional technology Large television receivers use cathode ray tubes (CR).
A speed modulation circuit (VM circuit) is added that modulates the scanning speed of the electron beam of T) at the contour of the image to emphasize the contour of the images on both sides and improve the clarity.

Generally, the signal input to this VM circuit is a luminance signal that has just been separated into a luminance signal and a chrominance signal using a comb filter, etc., and is the final signal that drives the CRT (contrast and chrominance signals). (signals that have been adjusted and controlled for image quality, etc.).

Problems to be Solved by the Invention However, in a VM circuit using such an input signal, even when the user adjusts the contrast to reduce the contrast, the input signal to the VM circuit does not change at all, so the input signal remains the same. Only VM effect works. That is, when viewed on the screen, the VM effect does not change even though the contrast is low and the screen is set to be calm, so there is a problem that only the outlines are emphasized and the screen is difficult to see.

Also, to solve this problem, it is possible to use the signal after the contrast and image quality have been adjusted as the input signal to the VM circuit, but in this case, since the signal at the location close to the CRT in terms of the circuit is used as the input signal. , the delay time to the CRT cathode is small, and in order to match the phase of the CRT cathode waveform and the VM coil current waveform, it becomes necessary to provide delay elements for the luminance signal and color signal, which increases costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a contour compensation device that can change the effect of contour compensation by VM according to the contrast adjusted by the user without increasing costs, and can always provide an easy-to-see image. It is.

Means for Solving the Problems In the present invention, the contour compensation effect by VM is controlled according to the contrast adjusted by the user, and a contrast adjustment voltage (DC voltage) is used to adjust the contrast. Accordingly, the limiting voltage of the amplitude limiting circuit of the VM circuit is controlled.

Function: The VM circuit of the present invention uses a contrast adjustment voltage to adjust the VM according to the contrast adjustment by the user.
To create a contour compensation effect by increasing the compensation effect when the contrast is high, and decreasing the compensation effect when the contrast is low, to moderate the emphasis of the contours on the screen, and to always display a screen that is easy to view without causing discomfort. This is what made it possible.

Embodiment Hereinafter, a contour compensation device using a VM circuit according to an embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 shows the configuration of the contour compensation circuit, in which an input signal (luminance signal) 9 passes through an amplifier circuit 1, and a differentiation circuit 2.
The contour of the image is detected by differentiation. The detection output is outputted to the output circuit 7 via the amplifier circuit 3 and the drive circuit 4.
The M coil 8 is driven and the deflection scanning speed of the electron beam is modulated to compensate for emphasizing the outline of the image. During this time,
A feedback circuit 6 that applies a limiter depending on the current of the output circuit element, and a diode limiter circuit 5 that applies a limiter to the amplitude above a certain range are provided.

FIG. 2 shows in detail the diode limiter circuit 5 shown in FIG. 1, and this circuit will be explained according to the diagram.

In order to limit the amplitude of the differentiated and amplified contour detection signal, conventionally, the voltage 18, which is fixed at a constant voltage, is divided by the resistors 12, 13, and 14.15.
Upper and lower limiters were applied to the voltage at the intersection of , and the voltage at the intersection of resistors 14° and 16, respectively. That is, the differential pulse is limited by the diode 10 and capacitor 16 on the upper side of the waveform, and is limited by the diode 11 and capacitor 17 on the lower side, so that the size of the differential waveform is always limited to a constant value.

In contrast, in the configuration of the present invention, the fixed voltage 18
Instead, a contrast adjustment voltage 3o is used, and the voltage is set according to the contrast adjustment by the user.

The circuit for applying this contrast adjustment voltage 30 will be explained with reference to FIG. is converted to The minimum value of this voltage 30 is determined by the resistors 19 and 20, and the maximum value is determined by the resistors 20 and 21, and is applied as the limiting voltage of the diode limiter circuit 6 for VM. The range of change can be freely controlled. The APL voltage 28 is added to the contrast voltage by resistors 26, 26, 27, and is input to the video-chroma IC as a contrast control voltage 29 to change the contrast of the luminance signal.

That is, the limiting voltage of the VM circuit is changed by the contrast voltage, which is not affected by the ABL voltage, so that the VM effect is made according to the contrast setting value, and a natural and easy-to-see screen is created.

Effects of the Invention As described above, since the contour compensation device of the present invention controls the contour compensation effect of the image according to the contrast adjustment voltage, the VM This is extremely advantageous in practical use, as it is possible to obtain, with a simple circuit, a screen that corresponds to the contrast, instead of one that had too large an effect and the contours were too emphasized, and which looked unnatural, to a more natural, calm, and calm screen.

[Brief explanation of drawings]

FIG. 1 is a basic block diagram of a contour compensating device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a diode limiter and vine circuit, and FIG. 3 is a circuit diagram of a contrast adjustment voltage generating circuit. 1.3... Amplifier circuit, 2... Differential circuit, 4... Drive circuit, 6... Diode limiter circuit, 6... Feedback limiter circuit, 7...output circuit, 8-...-V M
Carp w, 9, 18, 17.24... Capacitor, 10, 11, 23... Diode, 12,
13, 14, 15, 19, 20, 21゜22.25.2
6.27...ifc, 30...Contrast adjustment voltage. Name of agent: Patent attorney Shigetaka Awano? Gu or one person?
−−− pigeon cover

Claims (1)

[Claims] A contrast circuit that includes a circuit that detects the contour of the image, a speed modulation circuit that compensates for the contour of the image by modulating the scanning speed of the electron beam of the cathode ray tube according to the contour detection signal, and a contrast that adjusts the contrast of the image. A contour compensating device comprising a control circuit that increases the amount of compensation for the contour in accordance with the adjustment to increase the contrast under the control of an adjustment voltage.