JP4013358B2 - VM effect control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to image quality correction of a television receiver, and more particularly to an image quality correction apparatus that optimizes the effect of VM correction and improves image sharpness.
[0002]
[Prior art]
As a conventional velocity modulation device, for example, a device as disclosed in Japanese Patent Laid-Open No. 4-354271 is known.
[0003]
[Problems to be solved by the invention]
In the conventional technique, the VM signal for speed modulation has a certain signal level regardless of the large amplitude and small amplitude signals, and the VM effect applied to the image is uniform in all the images. The case of failure due to excessive effectiveness was inevitable.
[0004]
An object of the present invention is to control the output level of a VM signal as desired in order to avoid the failure of television images due to the excessive effect of the VM effect as described above.
[0005]
[Means for Solving the Problems]
V M effect control device of the present invention to solve the above object, detects a large amplitude signal portion of the VM signal, and a circuit for controlling only the amplitude of the large amplitude signal portion, detecting a small-amplitude signal portion of the VM signal And a circuit for controlling only the amplitude of the small amplitude signal portion.
[0006]
This improves the phenomenon in which a large VM effect has conventionally appeared in the large level signal portion and only a VM effect equal to or less than that of the large amplitude signal has appeared in the small level signal portion. As a result, it is possible to suppress an excessive effect of the large level signal portion to an appropriate effect amount.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
V M effect control device of the present invention is a (referred to as a Y signal.) Video luminance signal VM effect control device for generating a speed modulating signal (referred to as a VM signal.) From a large amplitude signal portion from the VM signal And a VM effect control device comprising: a means for detecting a small amplitude signal portion; and a large and small amplitude signal variable means for varying the output level of the VM signal corresponding to the large and small amplitude signal portion on a time axis. It is possible to appropriately correct the correction level of the VM correction in the television receiver with respect to the Y signal level of the video image and to improve the sharpness of the image.
(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0009]
FIG. 1 is a block diagram of a VM effect control apparatus according to the first embodiment of this invention.
[0010]
1 firstly differentiates the input Y signal to generate a VM signal. A buffer 2 outputs the VM signal to the VM signal amplifier circuit with low impedance. A circuit 3 amplifies all components of the VM signal. Reference numeral 4 denotes a buffer that outputs with low impedance to a circuit for extracting only a large amplitude portion from the VM signal. 5. Coring the VM signal from 4 outputs only the large amplitude portion, and connects the output to the amplifier circuit 3 to reduce the gain of the amplifier circuit. A buffer 6 outputs a signal after the waveform level of the VM signal is controlled.
[0011]
Reference numeral 7 denotes a drive circuit for generating a magnetic field by passing a current through the VM coil. Reference numeral 8 denotes a coil that performs velocity modulation on the beam current of the CRT. Reference numeral 9 denotes a collector resistor that determines the amplification factor of the amplifier circuit 3. Reference numeral 10 denotes an emitter resistor that determines the amplification factor of the amplifier circuit 3. Reference numeral 11 denotes a resistor that determines the amount of attenuation of only the large amplitude signal portion. Reference numeral 12 denotes a resistor that determines the amount of attenuation of only the large amplitude signal portion, similar to 11.
[0012]
In FIG. 1, reference numeral 1 denotes an operation for generating a VM signal from a Y signal, and is constituted by a primary differentiation circuit.
[0013]
As shown in FIG. 2, the level of the Y signal changes when the image of the television receiver changes from black to white, from gray to white, or from white to black in the horizontal direction. It is a signal that is created for speed modulation.
[0014]
A large amplitude signal and a small amplitude signal are detected from the signal output from the primary differentiation circuit. As shown in FIG. 2, a certain level from the center of the primary differential signal is set as the determination level of the large / small signal.
[0015]
The main line signal as the VM signal goes to the transistor 2, and the signal used for detection goes to the transistor 4.
[0016]
Reference numeral 2 denotes a circuit that delivers the VM signal to the amplifier circuit, and is configured by an emitter follower. Reference numeral 3 denotes a circuit for amplifying the VM signal, which is constituted by a grounded base amplification circuit, and the gain is determined by the resistor 9 and the resistor 10. The signal taken out for large amplitude signal detection is a circuit that sends the VM signal to the circuit 5 for detecting the large amplitude portion of the VM signal by 4 and is constituted by an emitter follower. Reference numeral 5 denotes a circuit for extracting a large amplitude signal portion of the VM signal, and is constituted by a coring circuit using the Vbe voltage of the transistor.
[0017]
The switching waveform of the large amplitude signal portion is output from the collector of the transistor 5, and the amount of amplification at 3 is connected in parallel with the resistor 9 and the resistors 10 and 11, and only the large amplitude signal portion can be attenuated. By this operation, the large amplitude signal 6 is a circuit for outputting the output from the VM effect control circuit and is constituted by an emitter follower. Reference numeral 7 denotes a VM drive circuit for driving the VM coil. Reference numeral 8 denotes a VM coil for performing velocity modulation on the electron beam in the CRT, and is composed of the coil.
[0018]
(Embodiment 2)
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a block diagram of the VM effect control apparatus according to the second embodiment of the present invention.
[0019]
In FIG. 3, 1 to 12 are the same as those shown in the first embodiment. However, 4 is a buffer that outputs to a circuit for extracting a signal for detecting a small signal portion of the VM signal, and is constituted by an emitter follower.
[0020]
Reference numeral 13 denotes a buffer that outputs with low impedance to a circuit for extracting only a large signal portion from the VM signal. Reference numeral 14 is a circuit for coring the VM signal from 13 and outputting only the large amplitude portion, and stopping the reduction of the amplification amount of 5 by 3 by the large signal portion. Reference numeral 15 denotes a resistor for stopping the attenuation of only the large amplitude signal portion. Reference numeral 16 denotes a resistor for stopping the attenuation of only the large amplitude signal portion as in the case of 15.
[0021]
In FIG. 3, the amplification amount of the small signal portion is determined by the amplification circuit 3 and the VM effect is controlled. The small amplitude signal shown in FIG. 4 is determined by the base bias value of the transistor 5. The large amplitude signal is determined by the base bias of the transistor 14.
[0022]
The VM output level intermediate between the small amplitude signal and the large amplitude signal is determined by the resistors 11 and 12 and can be varied within a range of a level smaller than that of the small amplitude signal. The VM signal output level that is a large amplitude signal becomes an output level equivalent to that of the small amplitude signal portion by switching of the transistor 14.
[0023]
As described above, the level of the VM output signal can be varied by separating into three levels of a small amplitude signal, a medium amplitude signal, and a large amplitude signal.
[0024]
【The invention's effect】
As described above, according to the present invention, the image of the television receiver can be subjected to a level-suppressed VM effect in the large amplitude portion of the Y signal and can have a large VM effect in the small amplitude portion of the Y signal. The optimal image quality correction can be performed and the level adjustment can be freely controlled.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a VM effect control device circuit according to a first embodiment of the present invention. FIG. 2 is a diagram showing a Y signal waveform, a CRT image, and a first-order differential waveform. FIG. 4 is a block diagram of a VM effect control device circuit according to a second embodiment. FIG. 4 is a diagram showing a determination level of a small amplitude signal and a large amplitude signal.
DESCRIPTION OF SYMBOLS 1 VM signal generation circuit 2 Emitter follower 3 VM signal amplification circuit 4 Emitter follower 5 VM signal coring circuit 6 Emitter follower 7 VM drive circuit 8 VM coil 9 VM signal amplification resistance (collector resistance)
10 VM signal amplification resistance (emitter resistance)
11 Large signal amplitude partial attenuation resistor 12 Large signal amplitude partial attenuation resistor 13 Emitter follower 14 VM large amplitude signal coring circuit 15 Large amplitude signal section attenuation stop resistor 16 Large amplitude signal section attenuation stop resistance

Claims (3)

A VM effect control device for generating a velocity modulation signal (VM signal) from a video luminance signal (Y signal), a means for detecting a large amplitude signal portion and a small amplitude signal portion from a VM signal, and the large and small amplitude signal portion Large and small amplitude signal variable means for varying the output level of the VM signal corresponding to the time axis, and the large and small amplitude signal variable means is a VM generated by first-order differentiation from the Y signal regardless of the magnitude of the Y signal. to the output value of the signal, certain have determination reference value, V M effect controller you characterized by arbitrarily changing the larger VM signal than the determination reference value. A VM effect control device for generating a velocity modulation signal (VM signal) from a video luminance signal (Y signal), the means for detecting a large amplitude signal portion and a small amplitude signal portion as separate values from the VM signal, Large amplitude signal variable means for varying the output level of the VM signal corresponding to the large amplitude signal portion on the time axis, and a small amplitude signal for varying the detected VM signal as a value different from the large amplitude signal A VM effect control device comprising a variable means. The large / small amplitude signal varying means has two output values, a large amplitude judgment value and a small amplitude judgment value, for the output value of the VM signal generated by first-order differentiation from the Y signal, regardless of the magnitude of the Y signal. 3. The VM effect control apparatus according to claim 2 , wherein a VM signal having a determination value for the magnitude is arbitrarily varied between a VM signal larger than the large level determination value and a VM signal smaller than the small level determination value. .

Images