JPH0419901Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a TV image monitoring device.

[Summary of the idea]

Approximately the horizontal video interval using a time axis compression circuit
This is an image monitor device that allows 100% of the image to fit within the effective screen.

[Conventional technology]

Home color television receivers display only about 80% of the video signals sent from broadcasting stations on the screen. This is because the effective screen is limited by problems with the linearity and registration of the deflection system. Note that some types of high-end monitor equipment for office use are capable of 100% display.

[Problem that the invention attempts to solve]

However, monitoring devices for office use are very expensive and consume a lot of power, so it is difficult to use them for home use.

The present invention aims to solve this problem and expand the effective screen using a low-cost, low-power consumption monitor device.

[Means for solving the problem] A time axis compression circuit is used to compress the time axis of the input video signal so that almost the entire horizontal video section falls within the width of the effective screen.

[Effect]

It is now possible to display video information outside the effective screen, which was previously deleted on home television receivers. The effective screen can be enlarged without using a monitor device having an expensive deflection system with very high horizontal deflection linearity. Note that the vertical deflection has a low frequency and has good linearity even in home-use television receivers, so the effective mask expansion in the vertical direction can be achieved by simply reducing the vertical amplitude. Therefore, there is no need to improve the deflection device, and it can be constructed at low cost.

〔Example〕

FIG. 1 is a block diagram of a TV image monitor device (TV receiver) to which the present invention is applied. The receiver 1 is equipped with a time-base compression circuit 2, and the input video signal after detection is time-compressed to about 80% in each horizontal period and is output to the video system 5. The time axis compression circuit 2 is a well-known digital (RAM, etc.) or analog (CCD)
, BBD, etc.) can be constructed using circuit technology.

The deflection system 6 is supplied with normal horizontal and vertical synchronization signals (15.7KH _Z and _60HZ , respectively) via the horizontal synchronization separation circuit 3 and the vertical synchronization separation circuit 4.

Figure 2A shows a horizontal sawtooth wave signal (horizontal deflection signal) formed in the deflection system 6, and the electromagnetic deflection system has good linearity in the section indicated by P (approximately 80% of the center of the horizontal section). , this section corresponds to the horizontal width of the effective screen. Therefore, when the input video signal shown in FIG. 2B is compressed by about 80% for each horizontal scan by the time axis compression circuit 2 as shown in FIG. Can be expanded.

On the other hand, in the vertical direction, the vertical width of the raster can be reduced by simply operating the vertical amplitude adjustment knob on the receiver. By operating this knob to reduce the amplitude of the vertical sawtooth current, the top and bottom edges of the raster will be within the CRT's effective screen, allowing 100% of the image information to be displayed vertically as well. become.

Note that when such an operation is performed, the entire vertical sawtooth wave from the start to the end is used for raster formation, but since the vertical scanning frequency is as low as _60Hz , the nonlinear distortion of the vertical deflection system is originally Image distortion in the vertical direction is not a problem.

The image obtained in this way is shrunk by about 80% in the horizontal and vertical directions within the effective screen, but a 100% image with no defects is obtained. There is no need to make any improvements to the linearity of the horizontal and vertical deflection systems, and the effective screen can be expanded.

In addition, in the conventional station monitor device, in order to expand the effective display screen in the horizontal and vertical directions, it is necessary to use a large current deflection device with excellent linearity, making it very expensive. However, according to the present invention, by simply adding the horizontal time axis compression circuit 2, the effective screen can be expanded without modifying the horizontal deflection system of the receiver. The time axis compression circuit 2 only needs to have a memory capacity for several lines at most, and the cost is not very high.

Note that it is convenient to provide the receiver with a switch for switching the effective screen between 80% and 100%. When this switch is set to 100%, the time axis compression circuit 2 shown in Fig. 1 is activated, and if the vertical amplitude is automatically reduced to about 80%, the effective screen can be adjusted arbitrarily by operating the switch. You can choose the size.

[Effect of idea]

As mentioned above, the present invention uses a time axis compression circuit to ensure that almost 100% of the horizontal video section falls within the effective screen, so it is not necessary to use an expensive monitor device with improved linearity of the deflection system of the receiver. Instead, you can get images with a large amount of information on a home-use TV set with an enlarged effective screen.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a TV image monitor device showing an embodiment of the present invention, and FIG. 2 is a signal waveform diagram. In addition, in the symbols used in the drawings, 1...TV receiver, 2...Time axis compression circuits 2, 3...
...Horizontal synchronization separation circuit, 4...Vertical synchronization separation circuit,
5...image system, 6...deflection system.

Claims (1)

[Scope of utility model registration request] A TV image monitor device equipped with a time axis compression circuit that compresses the time axis of an input video signal for each horizontal scan so that almost the entire horizontal video section falls within the effective screen.