JPH01160189A - Brightness correction device - Google Patents

Abstract

PURPOSE:To reduce the difference of brightness between a middle part and a corner by using a synthesis signal of horizontal and vertical periods so as to modulate a luminance signal. CONSTITUTION:A synchronizing signal (a) is supplied to a luminance correction device 1 and separated into a horizontal synchronizing signal (h) and a vertical synchronizing signal (v) by a synchronizing separator circuit 2, a signal h1 being the result of inverting the polarity of the horizontal synchronizing signal (h) supplied to the 1st square wave generating circuit 3 is outputted to a 1st sawtooth wave generating circuit 4 and a 1st differentiation circuit 5. Then a signal h2 is outputted to a 1st synthesis circuit 6 based on the signal h1 in a 1st sawtooth wave generating circuit 4 and a signal h3 is outputted to the 1st synthesis circuit 6 by differentiating the signal h1 by the 1st differentiation circuit 5. Then output signals h2, h3 are synthesized and a synthesis signal h4 is outputted to a synthesis means 11 and a synthesis signal v4 is outputted similarly based on the vertical synchronizing signal (v), the synthesis signals h4, v4 are synthesized and the luminance correction signal (b) is sent to a luminance control means 12. Thus, the luminance difference between the middle part and the corner is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a television receiver equipped with a display means using a cathode ray tube with a flat phosphor screen, for example, an F S (Flat 5 square) screen. The present invention relates to a brightness correction device suitable for application to.

[Prior art] In a conventionally known television receiver, the method shown in Fig. 5A
As shown in FIG. 1, a cylindrical CRT display (hereinafter referred to as CRT) whose fluorescent screen has a predetermined curvature was used.

In a CRT having such a shape, the brightness at the center and the brightness at some corners do not differ much.

However, in recent years, due to design trends, CRTs (FS) with flat fluorescent screens, as shown in Figure 5B, are increasingly being used.

In a CRT using such an FS tube, the width of the black stripe is wider as it approaches a corner compared to the center, and the width of the phosphor is roughly narrower at a corner compared to the center. It has become.

[Problems to be Solved by the Invention] Incidentally, the CRT having the above-described structure has a problem in that the brightness at the corners is approximately 30 to 50% lower than that at the center.

Therefore, the present invention solves these conventional problems with a simple structure, and controls the brightness signal in a display means using a cathode ray tube with a flat fluorescent screen to align the center and corners. The present invention proposes a brightness correction device that reduces the difference in brightness between the two parts.

[Technical means for solving the problem] In order to solve the above-mentioned problem, the present invention provides a brightness correction device for a display means using a cathode i-ray tube with a flat phosphor screen. a synchronization separation circuit that separates a signal into a horizontal synchronization signal and a vertical synchronization signal; first and second square wave generation circuits that invert and output the respective synchronization signals; and the first and second square wave generation circuits. first and second sawtooth wave generation circuits that generate sawtooth waves based on signals generated by the square wave generation circuits; and first and second sawtooth wave generation circuits that differentiate the signals generated by the first and second square wave generation circuits, respectively. the output signal of the first sawtooth wave generation circuit, the first synthesis circuit that synthesizes the output signal of the first differentiation circuit, the output signal of the second sawtooth wave generation circuit, and the second sawtooth wave generation circuit. a second synthesizing circuit that synthesizes the output signals of the differentiating circuit; a synthesizing means that synthesizes the output signals of the first and second synthesizing circuits; and a brightness control means that controls the luminance of the video signal by the output signal from the synthesizing means. It is characterized by having the following.

[Function] In this configuration, the synchronization signal a is supplied to the luminance correction device 1, and is divided into a horizontal synchronization signal and a vertical synchronization signal V in the synchronization separation circuit 2.

First, the horizontal synchronization signal is supplied to the first square wave generation circuit 3.

In the first square wave generation circuit 3, a signal h1 as shown in FIG. It can be output to.

In the first sawtooth wave generation circuit 4, a signal h2 as shown in FIG. 2B is outputted to the first synthesis circuit 6 based on the signal h1 supplied from the first square wave generation circuit 3.

In the first differentiating circuit 5, the first square wave generating circuit 3
By differentiating the signal h1 supplied from
A signal h3 as shown in FIG. C is output to the first synthesis circuit 6.

In the first synthesis circuit 6, output signals h2. h3 is synthesized, and a synthesized signal h4 as shown in the second diagram is output to the synthesizing means 11.

Similarly, each circuit based on the vertical synchronization signal V? , 8.
The composite signal v4 can be outputted to the combining means 11 via 9.10.

The combining means 11 combines the combined signal h4 and the combined signal v4, and sends a brightness correction signal as shown in FIG. 3 to the brightness control means 12.

As a result, the supplied video signal C is modulated in the luminance am means 12 based on the luminance correction signal S, and the signal d is supplied to the CRT using FSt.

If the brightness of the video signal ctt is modulated based on the brightness correction signal S in this way, the brightness will be higher in some corners than in the center, so even in display means using a cathode ray tube with a flat fluorescent screen. , it is possible to output an image in which the brightness of the center and corner parts does not differ much.

[Embodiment] Next, a case in which an example of the brightness correction device according to the present invention is applied to a television receiver equipped with an FS tube CRT will be described in detail with reference to FIG. 1 and subsequent figures.

FIG. 1 is a diagram showing the configuration of a television receiver 20 equipped with a brightness correction device 1 according to the present invention.

The television receiver 20 includes a brightness correction device 1, a video detection circuit 13, a CRT 14 using an FS tube, and the like.

In the video detection circuit 13, a video signal composed of a luminance signal, chroma (No. 8, etc.) is successfully detected, and the signal C is supplied to the luminance correction device l.

An FS tube is used as the CRT 14, and a brightness-corrected video signal d is supplied to the CRT 14.

Next, the configuration of the brightness correction device 1 according to the present invention will be explained in detail.

In the figure, 1 is a brightness correction device, and this brightness correction device 1 includes a synchronous separation circuit 2, first and second square wave generation circuits 3 and 7.
, first and second sawtooth generating circuits 4.8, first and second differentiating circuits 5, 9, first and second combining circuits 6.10. It is composed of a combining means 11 and a brightness control means 12.

A case will be described in which the brightness of the video signal C supplied from the video detection circuit 13 is corrected using the brightness correction device 1 configured as described above.

The positive polarity synchronization signal a supplied to the brightness correction device 1 is separated into a horizontal synchronization signal and a vertical synchronization signal V in a synchronization separation circuit 2.

The horizontal synchronization signal is supplied to the first square wave generation circuit 3,
The vertical synchronization signal V is supplied to the second square wave generation circuit 7.

In the first square wave generation circuit 3, the polarity of the supplied horizontal synchronizing signal is inverted to make it a negative polarity synchronizing signal, and the waveform is shaped to generate a signal as shown in FIG. 2A. h1 is obtained.

The signal h1 is output to the first sawtooth wave generating circuit 4 and the first differentiating circuit 5.

The second square wave generation circuit 7 also performs polarity inversion processing and waveform shaping processing on the supplied vertical synchronization signal V, and the signal v1 is sent to the second sawtooth wave generation circuit 8 and the second differentiation circuit 9.
is output to.

Signal h1. vl is the first and second sawtooth wave generation circuit 4.8
, a sawtooth signal h2. as shown in FIG. 2B is generated. v2 are formed, and these sawtooth signals h2. v2 is output to the first and second combining circuits 6 and 1o.

The first and second differentiating circuits 5.9 also receive the supplied signal h1. vl is differentiated, and a differential signal h3.vl as shown in FIG. 2C is obtained. v3 is obtained. These differential signals h3. v3
are supplied to the first and second combining circuits 6.10, respectively.

In the first and second combining circuits 6 and 10, the sawtooth wave generating circuit 4
．． 8 and the output signal h2. from the differentiating circuit 5.9. h3 and v2. h4.v3 are combined respectively, and a combined signal h4. v4 is obtained.

This composite signal h4. The signals v4 are respectively supplied to the combining means 11 and combined, thereby obtaining a luminance correction signal as shown in FIG.

This luminance correction (No. 8) is a signal in one vertical scanning period (IV) that is composed of multiple signals in one horizontal scanning period (IH), so if you enlarge part A in Fig. 3, it will be shown in Fig. 4. ◎ In other words, as shown in Figure 4, the brightness level is higher at the scanning start and end ends of the horizontal period than in the center.As for the vertical period, the scanning is also as shown in Figure 3. The brightness level at the start end and end end is higher than that at the center.

Therefore, the closer the brightness correction signal bLtcRT is to a corner, the higher the level, and the closer it is to the center, the lower the level of the signal.

The brightness correction signal having such a configuration is supplied to the brightness control means 12.

In the brightness control means 12, the video signal C from the video detection circuit 13 is brightness-modulated based on the brightness correction signal S. Thereafter, the video signal d after luminance correction is supplied to the CRT 14.

Therefore, since the brightness-corrected video signal d can be fully supplied to the CRT 14, an image is output in which the brightness of the center portion and the corner portions do not differ much.

In other words, in the center of a CRT using FST,
The brightness is high, and the closer you get to a corner, the lower the brightness. Therefore, by correcting the video signal C with a signal such as the brightness correction signal S whose level is higher as it approaches a part of the corner, an image with a small difference in brightness between the center part and the corner part is displayed.

[Effects of the Invention] As explained above, the present invention provides a synchronization system that separates a synchronization signal into a horizontal synchronization signal and a vertical synchronization signal in a brightness correction device for a display means using a cathode ray tube with a flat phosphor screen. a separation circuit, first and second square wave generation circuits that invert and output respective synchronization signals, and generate a sawtooth wave based on the signals generated by the first and second square wave generation circuits. first and second sawtooth wave generation circuits that differentiate the signals generated by the first and second square wave generation circuits, respectively; and a first sawtooth wave generation circuit. a first combining circuit that combines the output signal of the second differentiating circuit with the output signal of the first differentiating circuit; and a second combining circuit that combines the output signal of the second sawtooth wave generating circuit with the output signal of the second differentiating circuit. It is characterized by comprising: a circuit, a combining means for combining the output signals of the first and second combining circuits, and a brightness control means for controlling the brightness of the video signal by the output signal from the combining means. .

Therefore, according to the configuration of the present invention, when outputting a video signal in a display means using a cathode ray tube with a flat phosphor screen, the luminance signal is modulated by a composite signal of horizontal and vertical periods, so that It is possible to reduce the difference in brightness between the corner and the corner.

Therefore, the brightness correction device according to the present invention is extremely suitable for application to a television receiver or the like equipped with a display means using a cathode IJlff having a flat fluorescent screen as described above.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of the brightness correction device according to the present invention applied to a television receiver equipped with an FS tube CRT display, and FIG. 2 is a diagram showing each circuit in the brightness correction device according to the present invention. FIG. 2A is an output waveform diagram of a square wave generation circuit, FIG. 2B is an output waveform diagram of a sawtooth wave generation circuit, and FIG. 2C is an output waveform diagram of a differentiating circuit.
The second diagram is an output waveform diagram of the synthesis circuit, FIG. 3 is a diagram showing the output waveform from the composition means in the luminance correction device according to the present invention, and FIG. 4 is a partially enlarged diagram of the output waveform from the composition means.
FIG. 5 is a diagram showing the shape of a CRT display in a television receiver. FIG. 5A is a diagram showing a conventional CRT display, and FIG. 5B is a diagram showing a CRT display using an FS tube. 1... Brightness correction device 2... Synchronization separation circuit 3... First square wave generation circuit 4... First sawtooth wave generation circuit 5... First differentiating circuit 6... No. 1 synthesis circuit 7...Second square wave generation circuit 8...Second sawtooth wave generation circuit 9...Second differentiation circuit 10...Second synthesis circuit 11...Composition means 12... Brightness control means 14... CRT display 20 using FS't... Television receiver a... Synchronization signal b... Brightness correction signal C... Video signal h... Horizontal synchronization signal V...Vertical synchronization signal

Claims (1)

[Claims] (1) A brightness correction device for a display means using a cathode ray tube with a flat phosphor screen, which includes a sync separation circuit that separates a sync signal into a horizontal sync signal and a vertical sync signal, and a sync separation circuit that inverts each sync signal. first and second square wave generation circuits that output, first and second sawtooth wave generation circuits that generate sawtooth waves based on signals generated by the first and second square wave generation circuits; first and second differentiating circuits that differentiate the signals generated by the first and second square wave generating circuits, respectively; an output signal of the first sawtooth wave generating circuit; and an output of the first differentiating circuit. a first synthesis circuit for synthesizing signals; a second synthesis circuit for synthesizing the output signal of the second sawtooth wave generation circuit; and the output signal of the second differentiation circuit; and the first and second synthesis circuits. 1. A brightness correction device comprising: combining means for combining output signals of a circuit; and brightness control means for controlling brightness of a video signal using an output signal from the combining means.