JP3061848B2 - Contour compensator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour compensator using a velocity modulation circuit in a television receiver.

2. Description of the Related Art In a large television receiver, a cathode ray tube (CR)
A velocity modulation (VM circuit) that enhances the sharpness of the image of the image by modulating the scanning speed of the electron beam in T) at the outline of the image and improves the sharpness is added.

In general, as a signal input to the VM circuit, a luminance signal immediately after being separated into a luminance signal and a chrominance signal by a comb filter or the like is used, and a signal that drives a CRT (contrast or contrast) is finally used. Signal to which adjustment and control of image quality and the like have been added).

However, in a VM circuit using such an input signal, the input signal to the VM circuit does not change at all even when the user adjusts the contrast to be small. The same VM effect works. It is also the same when the user adjusts the sharpness similarly. In other words, when viewed on the screen, the VM effect does not change even though the contrast is small and the screen is set firmly and calmly, so that there is a problem that the screen becomes difficult to see with only the outline emphasized. Even when the sharpness is reduced, the VM effect does not change even though the screen is set to a softer one, so that there is a problem that the screen is displayed with only the outline emphasized.

Further, when the received signal is a noise screen, the noise signal is continuously amplified by the speed modulation circuit, so that the power in the output circuit 7 shown in FIG. Since the consumption increases sharply, and especially the temperature of the output transistor rises, a circuit for suppressing the noise signal is required.

In order to solve these problems, the signal after the contrast and image quality have been adjusted may be used as the input signal to the VM circuit, but in this case, the signal near the CRT in the circuit is used as the input signal. The delay time to the CRT cathode is small, and it is necessary to provide a delay element for the luminance signal and the chrominance signal in order to match the phases of the waveform of the CRT cathode and the current waveform of the VM coil, resulting in an increase in cost.

Further, the power consumption at the time of the noise signal is generally reduced by detecting the average current consumption flowing through the output transistor with a resistor, converting the voltage, and controlling the gain of the amplifier circuit 3.

The present invention does not increase the contrast, and adjusts the VM according to the contrast and sharpness adjusted by the user.
The contour compensation effect can be changed to obtain a video that is always easy to see, and at the time of a noise signal, the contour and the sharpness control voltage can be reduced to reduce the contour compensation effect and reduce the power consumption. It is an object to provide a compensation device.

Means for Solving the Problems In the present invention, the contour compensation effect by the VM is controlled in accordance with the contrast and sharpness adjusted by the user, and the contrast adjustment voltage (for adjusting the contrast and sharpness) is used. DC voltage), sharpness adjustment voltage (DC voltage), or DC voltage obtained by adding the contrast adjustment voltage and the sharpness adjustment voltage to control the control voltage of the VM circuit amplitude limiting circuit and determine whether or not there is a synchronization signal. Thus, when there is no synchronization signal such as a noise screen, the DC voltage is lowered to reduce the VM effect.

The VM circuit of the present invention uses only the contrast adjustment voltage, only the sharpness adjustment voltage, or a voltage obtained by adding two voltages, thereby performing contour compensation by the VM according to the contrast or sharpness adjustment voltage by the user. When the adjustment voltage is large, the compensation effect is increased, and when the adjustment voltage is small, the compensation effect is reduced, so that the contour on the screen is appropriately emphasized, and a screen that is always easy to see is displayed without discomfort. In addition, at the time of a noise screen where there is no synchronization signal, it is possible to reduce the adjustment voltage and reduce the power consumption of the VM output circuit more easily.

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

FIG. 1 shows a configuration of a contour compensation circuit.
The input signal (luminance signal) 9 passes through the amplifier circuit 1 and is differentiated by the differentiating circuit 2 to detect the outline of the image. The detection output is output from the output circuit 7 via the amplifier circuit 3 and the drive circuit to the VM.
The coil 8 is driven to modulate the deflection scanning speed of the electron beam to compensate for enhancing the contour of the image. During this time, a diode limiter circuit 5 is provided for applying a limiter to an amplitude exceeding a certain value.

FIG. 2 shows the circuit of the diode limiter circuit 5 shown in FIG. 1 in detail, and this circuit will be described with reference to the figure.

Conventionally, in order to limit the amplitude of the differentially amplified contour detection signal, a voltage 18 fixed to a constant voltage is divided by resistors 12, 13, 14, and 15, and the voltage at the intersection of the resistors 12, 13 is resistance
The upper and lower limiters were applied at the voltages at the intersections of 14,15. That is, the differential pulse is limited by the diode 10 and the capacitor 16 on the upper side of the waveform, and the diode 11 is
And the capacitor 17 to limit the magnitude of the differentiated waveform to a constant magnitude.

On the other hand, in the configuration of the present invention, the fixed voltage 18
Instead, the contrast adjustment voltage 30 or, in other cases, the sharpness adjustment voltage, and the voltage obtained by adding the contrast adjustment voltage 30 and the sharpness adjustment voltage, are used by the user to adjust the contrast and sharpness. The voltage is adjusted according to the adjustment.

First, a circuit for applying the contrast adjustment voltage 30 in the case of the interlocking type with contrast will be described with reference to FIG.

The voltage pulse for contrast adjustment output by the microcomputer 31 is converted into a DC voltage by the resistors 19, 20, 21, and 22, the diode 23, and the capacitor 24. The minimum value of this voltage 30 is determined by the resistors 19 and 20 and is applied as the control voltage 18 of the diode limiter circuit 5 for VM.
As a result, the width of change of the limit voltage can be freely controlled. The ABL voltage 28 is added to the contrast voltage by the resistors 25, 26, and 27, and is input as a contrast control voltage 29 to the video chroma IC to change the contrast of the luminance signal.

That is, the VM voltage is changed according to the set value of the contrast by changing the limit voltage of the VM circuit by the control voltage which is not affected by the ABL voltage, and a natural and easy-to-view screen is obtained.

Next, the sharpness interlocking type will be described. The circuit for applying the sharpness adjustment voltage has the same configuration as that shown in FIG. 3, but recently, the microcomputer 31 often outputs a DC voltage. This is the same for the contrast. This circuit configuration will be described with reference to FIG.

The DC voltage for sharpness adjustment output by the microcomputer determines the voltage operation range by the resistors 32, 33, 34, and 35 and is input to the video chroma IC 36 to control the image quality. Further, the voltage operation range is determined by the resistors 38, 39, and 40. A buffer circuit is formed by the transistor 41 and the resistor 42, and the voltage is applied as the limiting voltage 18 of the VM diode limiter circuit 5 from the emitter thereof. Vary the compensation effect.

Further, in the video chroma IC 36 in FIG.
A circuit for determining the presence or absence of a synchronization signal of the video signal is provided. Information on the presence or absence of the synchronization signal is input to the microcomputer 31 as a synchronization presence / absence determination signal 37. If linked, lower the contrast adjustment voltage 30; if sharpness linked, lower the sharpness adjustment voltage 44; if linked to both contrast and sharpness, lower only the contrast adjustment voltage 30 ,
Also, only the sharpness adjustment voltage 44 is reduced, or both voltages are simultaneously reduced to lower the VM effect, thereby reducing power consumption and preventing unnecessary noise from being subjected to contour compensation.

Next, a circuit linked with contrast and sharpness will be described with reference to FIG.

The contrast adjustment voltage 30 is formed by adding the sharpness adjustment voltage 43 with the resistors 49, 48 and 50 through the buffer circuit composed of the transistor 46 and the resistor 47 via the resistor 45, and limiting the VM diode limiter circuit 5. Applied as voltage 18. In this case, by changing the ratio of the resistors 48 and 49, it is possible to select whether the contrast is to be driven, the sharpness is to be driven, or the effect is the same.

In this way, an easy-to-view screen according to contrast and sharpness can be obtained, and the power consumption can be controlled by software using a microcomputer without adding an unnecessary VM effect at the time of a noise screen. Can be set to

Effects of the Invention As described above, the contour compensation device of the present invention limits the contour compensation effect of an image in accordance with the voltage for contrast adjustment and the voltage for sharpness adjustment. Even when the sharpness is reduced, the VM effect is too large and the contour is too emphasized, and from the feeling of discomfort, it is possible to obtain a more natural and moist screen according to the contrast and sharpness, as well as noise In a screen, it is possible to easily obtain the outline without emphasizing the outline and to reduce the power consumption, which is extremely advantageous in practical use.

[Brief description of the drawings]

FIG. 1 is a basic block diagram of a contour compensator according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a diode limiter circuit, FIG. 3 is a circuit diagram of a contrast adjustment voltage generation circuit,
FIG. 4 is a circuit diagram of a sharpness adjustment voltage generation circuit, and FIG. 5 is a circuit diagram of a circuit for mixing a contrast adjustment voltage and a sharpness adjustment voltage. 1,3 ... amplifier circuit, 2 ... differential circuit, 4 ... drive circuit, 5 ... diode limiter circuit, 7 ... output circuit,
8… VM coil, 9,16,17,24 …… Capacitor, 10,11,23
…… Diode, 12,13,14,15,19,20,21,22,25,26,27,3
2,33,34,35,38,39,40,42,45,47,48,49,50… Resistance, 30
…… Contrast adjustment voltage, 41,46 …… Transistor, 4
3 ... Sharpness adjustment voltage.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-249366 (JP, A) JP-A-2-30276 (JP, A) JP-A-61-210769 (JP, A) JP-A-52-1 74220 (JP, A) JP-A-58-159068 (JP, A) JP-A-59-20311 (JP, A) JP-A-2-57670 (JP, U) JP-A-60-155265 (JP, U)

Claims (1)

(57) [Claims] 1. A contour detection circuit for detecting a contour of an image, a speed modulation circuit for compensating for a contour of an image by modulating a scanning speed of an electron beam of a cathode ray tube according to the contour detection signal, and a contrast of the image. A contrast adjustment voltage creating circuit for creating a contrast adjustment voltage for adjusting the sharpness; a sharpness adjustment voltage creating circuit for creating a sharpness adjustment voltage for adjusting the image sharpness; and a contour compensation amount control for controlling the contour compensation amount of the speed modulation circuit. Means, a synchronization signal detection circuit, and an adjustment voltage control means for controlling the contrast adjustment voltage creation circuit and the sharpness adjustment voltage creation circuit based on a detection signal from the synchronization signal detection circuit; and The output contour compensation amount is adjusted by the contrast adjustment voltage and / or the sharpness adjustment. When the detection signal from the synchronization signal detection circuit indicates a synchronization signal “absent”, both the contrast adjustment voltage and the sharpness adjustment voltage are simultaneously reduced to a predetermined voltage value or less by the adjustment voltage control circuit. The contour compensation amount is controlled by the contour compensation amount control means so as to decrease the contour compensation amount of the speed modulation circuit according to the contrast adjustment voltage and the sharpness adjustment voltage that are equal to or less than the predetermined voltage value.
A contour compensator wherein power consumption is not increased even in a noise screen.