JPH11341308A - Image quality adjustment circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive image quality adjustment circuit, without adopting complicated and expensive circuit constitution by controlling the amplitude of blanking pulses and a DC potential based on a parameter which has been set beforehand to a variable means. SOLUTION: A blanking pulse generating circuit 2 generates blanking pulses from the synchronizing signals of video signals displayed on a CRT 8. A preceding stage amplifier circuit 5 controls the amplitude of the blanking pulses generated from the blanking pulse generation circuit 2 and adds and also amplifies the video signals. A poststage amplifier circuit 6 amplifies the video signals amplified in the preceding stage amplifier circuit 5, to a level required for driving the CRT 8. A DC reproduction circuit 7 sets the video signals amplified in the poststage amplifier circuit 6 to the DC potential optimum for driving the CRT 8. A control circuit 4 controls the preceding stage amplifier circuit 5 and the DC reproduction circuit 7, so as to control the amplitude of the blanking pulses and the DC potential, based on the parameter which has been set beforehand to the variable means 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality adjusting circuit for a display device using a CRT, and more particularly to an image quality adjusting circuit provided with a means for improving image quality.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional image quality adjusting circuit comprises a matrix circuit for forming a luminance signal from input red, green and blue primary color signals, and a contour correction from a luminance signal selected from the matrix circuit. A signal forming circuit for forming a signal is provided, and an outline correction signal obtained from the signal formation is combined with an input primary color signal of red, green, and blue, and the amplitude (V1) of the blanking pulse is adjusted by a preamplifier circuit. The signal is processed inside the pre-amplifier circuit 105 so as to be equal to the reference voltage (V1) applied to the signal 105, and the post-amplifier circuit 6 inverts and amplifies the signal b output from the pre-amplifier circuit 105. The inverted and amplified signal c is applied to the CRT 8 through a DC reproducing circuit 7 for applying a DC potential necessary for driving the CRT 8, and a video signal d is displayed.

[0003]

Therefore, it is known that the conventional image quality adjustment circuit increases the sharpness by performing signal processing in accordance with the video signal to be displayed. There is a problem that the circuit configuration is complicated because the circuit is configured on the signal line, and that the circuit configuration for three colors of red, green, and blue of the video signal is expensive because the circuit configuration is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive image quality adjustment circuit which only controls the DC potential of a video amplifier circuit without taking a complicated and expensive circuit configuration.

[0005]

In order to solve the above-mentioned problems, an image quality adjustment circuit according to the present invention comprises a CRT for displaying a video signal transmitted from a host system based on a synchronization signal.
A blanking pulse generating circuit for generating a blanking pulse from a synchronizing signal of the video signal displayed on the CRT; and controlling the amplitude of the blanking pulse generated by the blanking pulse generating circuit to convert the video signal. A pre-amplifier circuit for adding and amplifying, a post-amplifier circuit for amplifying the video signal amplified by the pre-amplifier circuit to a level required for driving the CRT, and a video signal amplified by the post-amplifier circuit A DC regeneration circuit for setting a DC potential optimal for driving the CRT, and the amplitude of the blanking pulse and D
The control circuit controls the preamplifier circuit and the DC regeneration circuit so as to control the C potential.

[0006]

Next, an image quality adjusting circuit according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram (A) of an image quality adjusting circuit and a waveform diagram (B) of an outline correction signal according to an embodiment of the present invention.

FIG. 2 is an image signal waveform diagram of the image quality adjusting circuit according to one embodiment of the present invention.

As shown in FIG. 1, a picture quality adjusting circuit according to an embodiment of the present invention includes a CRT 8 for displaying a video signal transmitted from a host system 1 based on a synchronization signal,
A blanking pulse generating circuit 2 for generating a blanking pulse from a synchronizing signal of a video signal displayed on the CRT 8 and a video signal added by controlling the amplitude of the blanking pulse generated from the blanking pulse generating circuit 2 Amplifying circuit 5 for amplifying and amplifying the video signal, amplifying the video signal amplified by the amplifying circuit 5 to a level necessary for driving the CRT 8, and a video signal amplified by the amplifying circuit 6 Regeneration circuit 7 for setting the DC potential to the optimal DC potential for driving the CRT 8, and a preamplifier circuit 5 and a DC regeneration circuit for controlling the amplitude of the blanking pulse and the DC potential based on the parameters set in advance in the variable means 3. And a control circuit 4 for controlling the control circuit 7.

Next, the operation of the image quality adjustment circuit according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the operation of the image quality adjustment circuit according to one embodiment of the present invention is as follows. First, the preamplifier circuit 5 shown in FIG.
When the voltage of the control voltage V1 is increased, the waveform b shown in FIG.
2, the amplitude of the blanking pulse increases and the solid line changes from the dotted line of b1 in FIG. 2 to the solid line. This is because the DC component of the video signal input to the post-amplifying circuit 6 increases, and the output of FIG. The image portion of c1 shows the tendency of the waveform 2 of FIG. 1B, but with the amplitude of the blanking pulse increased, the video signal of the cathode for the grid 1 of the CRT 8 of FIG. Since the luminance increases as the voltage approaches the voltage V2, the control circuit 4 simultaneously increases the voltage V2 by the DC regeneration circuit 7 so as to increase the DC voltage as shown by d1 in FIG.

On the other hand, when the voltage V1 of the preamplifier circuit 5 shown in FIG.
Waveform b in FIG. 3 shows that the amplitude of the blanking pulse is reduced and FIG.
From the dotted line of b2 to a solid line. This is because the DC component of the video signal input to the post-amplifying circuit 6 becomes low.
The output image portion of c2 in FIG. 2 shows the tendency of the waveform 2 in FIG. 2B, but if the amplitude of the blanking pulse is kept small, the video signal of the cathode with respect to the grid 1 of the CRT 8 in FIG. Since the luminance decreases as the voltage becomes longer by the voltage V3 of c2 in FIG. 2, in order to maintain the predetermined luminance, the voltage V2 is simultaneously reduced by the control circuit so that the DC voltage is reduced by the DC regeneration circuit 7 as shown by d2 in FIG. Do.

[0013]

As described above, according to the image quality adjusting circuit of the present invention, since the image quality can be adjusted by controlling the DC potential of the image amplifying circuit, the circuit configuration is simple and inexpensive. There is.

[Brief description of the drawings]

FIG. 1A is a block diagram of an image quality adjustment circuit according to an embodiment of the present invention, and FIG.

FIG. 2 is a video signal waveform diagram of the image quality adjustment circuit according to one embodiment of the present invention.

FIG. 3 is a block diagram of a conventional image quality adjustment circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 host system 2 blanking pulse generation circuit 3 variable means 4 control circuit 5 preamplifier circuit 6 postamplifier circuit 7 DC regeneration circuit 8 CRT

Claims (1)

[Claims] 1. A CRT for displaying a video signal transmitted from a host system based on a synchronization signal, a blanking pulse generation circuit for generating a blanking pulse from a synchronization signal of the video signal displayed on the CRT, A pre-amplifier circuit for adding and amplifying the video signal by controlling the amplitude of a blanking pulse generated from a blanking pulse generation circuit, and a video signal amplified by the pre-amplifier circuit are required for driving the CRT. Based on a parameter set in advance in a variable means, a DC reproduction circuit for setting the video signal amplified by the latter amplification circuit to a DC potential optimal for driving the CRT,
An image quality adjustment circuit, comprising: a control circuit that controls the preamplifier circuit and the DC reproduction circuit so as to control the amplitude of the blanking pulse and the DC potential.