JPS63272175A - Scanning speed modulating circuit - Google Patents

Abstract

PURPOSE:To reduce cost, a mounting space, and power consumption and to facilitate the control by sharing one amplifying means between horizontal and vertical VM signals. CONSTITUTION:The horizontal VM signal outputted from a horizontal VM signal generating circuit 6 and the vertical VM signal outputted from a vertical VM signal generating circuit 6 are inputted to an adding and mixing circuit 7 and are added and mixed there. The output of the circuit 7 is supplied to an amplifying circuit 8 after processings such as noise component elimination. The inputted mixed signal is amplified by the amplifying circuit 8 and is inputted to a horizontal/vertical separating circuit 9 and is separated into the horizontal VM signal and the vertical VM signal again. Thus, only one amplifying circuit is used to considerably reduce the cost, the mounting space, and the power consumption. Both of horizontal and vertical VM signals are amplified only by the amplifying circuit for horizontal VM to considerably improve the use efficiency of the circuit.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a television receiver (hereinafter abbreviated as ゛V).

) and the like, and particularly relates to a scanning speed modulation circuit that improves the sharpness of a displayed image.

[Conventional technology]

In image display devices such as TVs, there is a scanning speed modulation circuit as a means for improving the sharpness of displayed images. This is achieved by driving a sub-deflection device independent of the main deflection device using a scanning speed modulation signal to change the scanning speed of the electron beam in the cathode ray tube at the edge of the image, thereby changing the sharpness by changing the brightness. It is intended to improve

Now, scanning velocity modulation (hereinafter referred to as VelocityModu)
abbreviated as VM. ) will be briefly explained using FIG.

FIG. 3 is an explanatory diagram for explaining the principle of scanning speed modulation. In FIG. 3, the horizontal axis represents time, or the horizontal or vertical axis of the display surface.

FIG. 3(a) shows the original video signal waveform. Figure 3(a)
In general, if the horizontal axis is represented by time, the vertical axis is represented by voltage or current, and if the horizontal axis is represented by the horizontal or vertical axis of the display surface, the vertical axis is represented by brightness. .

Now, if the original video signal shows a simple step-like change as shown in FIG. High frequency components are lost. For example, in Figure 3 (
In a), the slope of the brightness change in the contour portion is gentle, resulting in an image that visually lacks sharpness.

By the way, the human eye is sensitive to changes, so in order to increase the sharpness of the above-mentioned displayed image, it is best to make the display brightness change as shown in Figure 3 (b). generally known.

Therefore, as a means for producing a luminance change as shown in FIG. 3(b), there is a circuit called an aperture compensation circuit or a peaking circuit that emphasizes only the outline of the video signal. This is commonly used,
By changing the intensity of the cathode ray tube's electron beam (in other words, the magnitude of the beam current) at the outline of the image,
The brightness changes as shown in FIG. 3(b) are used to emphasize the outline and improve the sharpness.

However, when displaying a high-brightness area, the intensity of the electron beam is strong and the beam diameter of the electron beam becomes thick even if it is displayed normally, making it difficult to display with high definition. In the circuit or peaking circuit, when displaying this high brightness area, it is displayed with an even stronger electron beam than when displaying through, so naturally the beam diameter of the electronic beano becomes thicker. Therefore, there was a problem in that it became even more difficult to display with high definition.

Therefore, as another method for producing the brightness change as shown in Figure 3(b) without changing the intensity of the electron beam of the cathode ray tube, we have proposed an alternative method of changing the scanning speed of the electron beam to the image. VM
was devised.

VM uses the principle that if the same location of the phosphor is excited with an electron beam for a long time, the brightness will increase, but if it is short, the brightness will decrease. This can be achieved using a deflection magnetic field as shown in Figure (c). In other words, if the deflection magnetic field, which increases in a single manner, is increased or decreased at the contour of the video signal, the scanning speed of the electron beam will be modulated, producing a brightness change as shown in Figure 3(b). .

In order to realize the deflection magnetic field as shown in Fig. 3(e), the third
A scanning velocity modulation signal (hereinafter referred to as VM multiplied signal) shown in Fig. 3(d) is obtained as a first-order differential waveform of the contour part of the original video signal in Fig. 3(a), and the deflection device is driven by this VM multiplied signal. ,
It is sufficient to generate a magnetic field in the direction (G) of FIG. 3(C).

The above explanation using FIG. 3 can be applied to the horizontal direction of the display surface as well as to the vertical direction.

Note that related devices of this type include, for example,
JP-A-60-163576, JP-A-60-192
467, Japanese Patent Publication No. 55-37903, and Japanese Patent Publication No. 56-13064.

Examples include Japanese Patent Publication No. 60-41912.

[Problem that the invention seeks to solve]

The above conventional technology is highly effective in improving sharpness in high-quality conditions, but in order to have both horizontal and vertical effects, the VM signal generation circuit, sub-deflection drive circuit (
In other words, an amplifier circuit that amplifies the signal by VM times), a sub-deflection device (
For example, two independent systems in the horizontal and vertical directions were required, such as a sub-deflection coil (made with a pudding 1 coil, etc.).

Therefore, in the conventional technology described above, if scanning speed modulation is performed in both horizontal and vertical directions, the cost will be high, the mounting space will be large, and the power consumption will also increase, which makes it extremely difficult to commercialize the product. Therefore, a compromise has generally been made with scan velocity modulation only in the horizontal direction.

The purpose of the present invention is to solve the problems of the prior art described above,
It is an object of the present invention to provide a scanning speed modulation circuit that can effectively modulate the scanning speed in both horizontal and vertical directions while minimizing deterioration in cost, installation space, and power consumption.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention includes a horizontal scanning velocity modulation signal generating means for inputting a video signal, differentiating a horizontal contour component of an image, and creating and outputting a horizontal scanning velocity modulation signal; vertical scanning velocity modulation signal generating means for manually generating the video signal and differentiating the vertical contour components of the image to create and output a vertical scanning velocity modulation signal; a mixing means for mixing a velocity modulation signal; an amplification means for amplifying a mixed signal from the mixing means; and an amplification means for amplifying the mixed signal from the mixing means; a horizontal deflection means for deflecting the electron beam in the cathode ray tube, and a sub-deflection means for horizontal deflection arranged independently of the main deflection means, which deflects the electron beam in the cathode ray tube. supplying the horizontal scanning velocity modulation signal and supplying the vertical scanning velocity modulation signal from the separation means to a sub-deflection means for vertical deflection to modulate the scanning velocity of the electron beam in the cathode ray tube; This is what I did.

[Effect]

In the present invention, the horizontal scanning velocity modulation signal outputted from the horizontal scanning velocity modulation signal generation means and the vertical scanning velocity modulation signal outputted from the vertical scanning velocity modulation signal generation means are combined by γR in the mixing means. After that, the signal is input to the amplification means and amplified, so that only one amplification system is required, whereas conventionally two systems are required, and cost, mounting space, and power consumption can be significantly reduced. Further, the amplified mixture (No. 8) is separated in the separation means by utilizing the difference in frequency band between the +ii7 horizontal scanning speed modulation (No. 3) and the vertical scanning speed modulation signal. The horizontal scanning velocity modulation signal is supplied to the sub-deflection means for horizontal deflection, and the vertical scanning velocity modulation signal from the separation means is supplied to the sub-deflection means for vertical deflection, thereby scanning the electron beam in the cathode ray tube. By modulating the speed, brightness changes can be caused in the contours in the horizontal and vertical directions, thereby improving the sharpness of the displayed image.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, ■ is a video signal input terminal, 2 is a main signal system, 3 is a scanning speed modulation circuit (hereinafter abbreviated as VM circuit),
4 is a cathode ray tube, 5 is a horizontal VM signal generation circuit, and 6 is a vertical V
M signal generation circuit, 7 is an addition 7H combination circuit, 8 is an amplifier circuit,
9 is a horizontal/vertical separation circuit; 10 is a horizontal sub-deflection coil; 11
5 is a vertical sub-deflection coil, 21 is a delay circuit, 22 is a video signal processing circuit, 51 is a horizontal delay circuit, 52 is a subtraction circuit, 5
3 is a variable gain circuit, 61 is a vertical delay circuit, 62 is a subtraction circuit, and 63 is a variable gain circuit.

As shown in FIG. 1, a video signal input to an input terminal 1 is divided into two parts and supplied to a main signal system 2 and a VM circuit 3, respectively. The video signal input to the main signal system 2 is input to the cathode ray tube 4 via a delay circuit 21 and a video signal processing circuit 22.

On the other hand, the video signal input to the VM circuit 3 is branched into two branches and input to a horizontal VM signal generation circuit 5 and a vertical VM signal generation circuit 6, respectively.

In the Mizuko VM signal creation circuit 51, a horizontal delay circuit 51 and a subtraction circuit 52 create a horizontal VM multiplied signal in which only the horizontal contour component of the video content is first differentiated from the video signal, and a variable gain circuit 53. Here, the delay time Δτ□ of the horizontal delay circuit 51 is related to the emphasis frequency (peaking frequency) in the horizontal direction, and is generally determined while also taking into account the size of the screen. and,
This time Δτ1. When the delayed signal and the original video signal are subtracted in the subtraction circuit 52, a first-order differential signal, which is a horizontal contour signal of the image, that is, a horizontal VM multiplied signal is obtained.

Similarly, in the vertical VM signal generation circuit 6, a vertical delay circuit 61 and a subtraction circuit 62 generate a vertical VM multiplied signal in which only the contour component in the vertical direction is first differentiated. is output. However, the only difference from the horizontal VM signal generation circuit 5 is the vertical delay circuit 6.
1 delay time Δrv is different, Δτv=IH(=
Horizontal period: approximately 63.5 μs). This is because vertical edge enhancement is performed by emphasizing adjacent scan lines. In this way, the vertical delay time Δτ
9 has a horizontal delay time ΔτH of 150 ns to 250 ns.
ns, the horizontal delay time Δτ□
There is a large gap.

In other words, the created horizontal VM
There is a considerable gap between the double signal frequency band and the vertical VM double signal frequency band (the horizontal VM double signal is mainly on the high frequency side,
The vertical VM double signal is mainly on the low frequency side. ).

This embodiment utilizes the difference in the frequency bands of the horizontal VM double signal and the vertical VM double signal. That is, in the sharpness improvement method using a VM circuit, a large burden is placed on the amplifier circuit (consisting of a power amplifier) 8 for passing the VM signal to the inductance, which is the sub-deflection coil 10, 11. In this embodiment, the above-mentioned difference in the frequency bands of the horizontal and vertical VM multiplied signals is used to mix both signals and use the amplifier circuit 8 in common.

In other words, the horizontal V output from the horizontal VM signal generation circuit 5
The M-fold signal and the vertical VM-fold signal output from the vertical VM signal generation circuit 6 are input to the addition/mixing circuit 7, which adds and mixes the two and further performs processing such as removing noise components. The signal is then supplied to the amplifier circuit 8.

The input mixed signal is amplified in the amplifier circuit 8, and then input to the horizontal/vertical separation circuit 1), where it is again separated into the horizontal VM multiplied signal and the vertical VM (, ', signal. That is, the horizontal The vertical separation circuit 9 is composed of a filter that separates the input mixed signal into high frequency components and low frequency components, converts the high frequency component into a horizontal VM multiplied signal, supplies it to the horizontal sub-deflection coil 10, and outputs the low frequency component. is multiplied by vertical VM and supplied to the vertical sub-deflection coil 11.

A VM magnetic field is generated which changes the main deflection magnetic field of the M times signal supplied to these sub-deflection coils 10 and 11. This situation is as shown in FIG. 3, as already explained.

In this way, the scanning speed of the electron beam in the cathode ray tube 4 is modulated by the VM signal generated from the video signal, and brightness changes occur on the contours in both the horizontal and vertical directions on the display screen, improving the sharpness. It looks like Further, it goes without saying that the brightness increase by the sharpness improvement method using the VM circuit has no effect on the spot diameter of the electron beam.

Note that the horizontal VM signal generation circuit 5. Vertical VM signal generation circuit 6
The variable gain circuits 53 and 63 within the horizontal VM signal,
This increases or decreases the amplitude of the vertical VM signal, that is, the amount of contour correction (contour enhancement), and if it is linked with image contrast adjustment, natural contour enhancement becomes possible.

As described above, according to this embodiment, only one amplifier circuit system is required compared to conventionally two systems, and cost, installation space, and power consumption can be significantly reduced. Furthermore, it is possible to amplify both the horizontal VM multiplied signal and the vertical VM multiplied signal using only the conventionally used horizontal VM amplifier circuit, and the circuit utilization efficiency is greatly improved.

Next, the main circuits shown in FIG. 1 will be explained in more detail using FIG. 2.

FIG. 2 is a circuit diagram showing a specific example of the main circuits in FIG. 1.

The horizontal VM multiplied signal and the vertical VM multiplied signal inputted into the addition/mixing circuit 7 shown in FIG. The variable resistors 71 and 72 are used by the user to adjust the horizontal and vertical transverse 2B correction amounts, and their respective resistance values are:
Just look at the actual screen and set it to look the best. Further, the total contour correction amount for the entire screen can be adjusted by the total correction amount adjustment variable resistor 73.

In addition, as another configuration, instead of the total correction amount adjustment variable resistor 73, a total correction amount adjustment circuit is provided between the addition mixing circuit 7 and the amplifier circuit 8, and it is made to work in conjunction with contrast adjustment. It is possible to reproduce natural and high-quality screens. In that case, it can be easily realized by constructing the total correction amount adjustment circuit with a differential amplifier type gain adjustment circuit used in an IC circuit or the like.

Next, the transistor 81 in the amplifier circuit 8 shown in FIG.
82 constitutes a base clip circuit by using PNP type and NPN type transistors in an unbiased state, and the input mixed signal is noise-free due to the base-emitter threshold (1.4V each). is removed. This mixed signal is then amplified by the output 1 transistors 83 and 84 and input to the horizontal/vertical separation circuit 9.

Next, the horizontal/vertical separation circuit 9 converts the horizontal voltage to the horizontal voltage as shown in FIG.
It consists of an M output capacitor 91 and a vertical VM output capacitor 92. However, in reality, the horizontal ■M output capacitor 91
C11, LH of the horizontal sub-deflection coil 10, Cv of the vertical VM output capacitor 92, Lv of the vertical sub-deflection coil 11 constitute a filter, and this filter separates the horizontal VM signal and the vertical VM multiplied signal. are doing. That is, the value of C1°Lll is made much smaller than the values of Cv and Lv, so that only a high frequency current, that is, a horizontal VM signal current flows through the horizontal sub-deflection coil 10.

On the other hand, by making the values of Cv and Lv larger than the value of CH+Ll+, the vertical sub-deflection coil 11 receives a low frequency current,
That is, only the vertical VM signal current is allowed to flow. By doing this, the horizontal VH times the vertical V
M-fold signal separation, horizontal sub-deflection coil 10. Each of the vertical sub-deflection coils 11 is driven. In this way, by making the impedances of the output capacitor and the sub-deflection coil different between the horizontal and vertical directions, it is possible to separate the VM multiplied signals in the horizontal and vertical directions.

In this embodiment, a case will be described in which the electron beam in the cathode ray tube 4 is deflected by electromagnetic deflection, and the amplifier circuit 8
The load is the inductance, i.e. the sub-deflection coil 10.1
1, the electron beam may be deflected by electrostatic deflection, and in that case, the load of the amplifier circuit 8 becomes capacitance.

〔Effect of the invention〕

According to the present invention, since one amplification means is shared by the horizontal VM multiplied signal and the vertical VM multiplied signal, only one amplification means is required compared to the conventional two systems, reducing cost, installation space, and
Power consumption can be significantly reduced, the amplification means etc. can be controlled very easily, and the amount of contour correction in the horizontal and vertical directions can be easily balanced. In addition, the amplification means is the part with the largest time delay in the VM circuit, but as mentioned above,
Since the amplification means is common for the horizontal VM double signal and the vertical VM double signal, there is no need to adjust the time delay of the horizontal VM double signal, vertical M double signal, and therefore the main signal system and the VM double signal.
Since it is only necessary to adjust the time delay of the multiplication signal, the time delay adjustment becomes easy and the burden of stability management during mass production is halved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific example of the main circuit in FIG. 1, and FIG. This is an explanatory diagram. Explanation of symbols 3...Scanning speed modulation circuit, 4...Cathode ray tube, 5...Horizontal VM signal generation circuit, 6...
... Vertical VM signal generation circuit, 7 ... Addition mixing circuit, 8 ... Amplification circuit, 9 ... Horizontal/vertical separation circuit, 10 ... Horizontal Sub-deflection coil, 1■
・・・・・・Vertical sub-deflection coil. Agent Patent Attorney Akio Namiki Figure 3

Claims (1)

[Claims] 1. In an image display device that displays images using a cathode ray tube, a video signal is input, a horizontal contour component of the image is differentiated, and a horizontal scanning velocity modulation signal is created and output. a horizontal scanning speed modulation signal generating means, inputting the video signal;
Vertical scanning velocity modulation signal generating means for differentiating vertical contour components of an image to create and output a vertical scanning velocity modulation signal, and mixing the outputted horizontal scanning velocity modulation signal and vertical scanning velocity modulation signal. a mixing means, an amplifying means for amplifying the mixed signal from the mixing means, and separating the amplified mixed signal into the horizontal scanning speed modulation signal and the vertical scanning speed modulation signal based on the difference in frequency bands, and outputting each of the signals. separating means, and transmitting the horizontal scanning velocity modulation signal from the separating means to sub-deflection means for horizontal direction deflection, which is arranged independently of the main deflection means and which deflects the electron beam in the cathode ray tube. and the vertical scanning velocity modulation signal from the separation means is supplied to a sub-deflection means for vertical deflection to modulate the scanning velocity of the electron beam in the cathode ray tube. Speed modulation circuit.