JPH02194783A - High-definition projection tv - Google Patents

Abstract

PURPOSE:To prevent a burnt step from being generated on the picture displaying surface of a projection tube by inputting a standard television signal to the projection tube after converting the aspect ratio of the standard television signal so as to conform to that of high-definition television. CONSTITUTION:The standard television signal is inputted to the projection tube 1 after converting it into a signal long sideways so that a residual part is not generated at the picture displaying surface of the projection tube 1. Next, a standard television signal picture displayed as filling the picture displaying surface of the projection tube 1 is converged by a projection lens 2, and is narrowed in its deflection angle in only a horizontal direction by a light flux conversion lens 3, and is projected on a screen. Thus, the generation of the burnt step of the fluorescent surface of the projection tube 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-definition projection TV that can also display standard television signals (hereinafter referred to as television).

[Summary of the invention]

In high-definition projection TVs that can display high-definition television format signals and standard television format signals with different aspect ratios, standard television signals are projected to prevent burn-in steps on the fluorescent surface of the projection tube. When projecting from a projection tube onto a screen, the horizontal and vertical scanning amplitudes are adjusted to make the aspect ratio equal to that of a high-definition television system, and when projected from a projection tube onto a screen, a light flux conversion lens is used to adjust the aspect ratio to that of a standard television system. It is characterized by returning.

[Conventional technology]

By displaying detailed television images on a large wide screen, high-definition television aims to provide new appeal such as power and presence that cannot be obtained with current standard television broadcasting. But interest is growing. This high-definition television is the Japan Broadcasting Corporation (
It was proposed by NHK) and has a screen aspect ratio of 9:16 (vertical: horizontal) and 1125 scanning lines, which is different from the current standard television (3:4 aspect ratio, 525 scanning lines).

Figure 4 shows the state when a standard TV signal is projected onto the projection tube of a conventional high-definition projection TV.A projection tube with an aspect ratio of 9:16 has an aspect ratio of 3:4.
Standard television signals have different aspect ratios, so if the screen is displayed with the same length in the vertical direction, residual portions 13 will appear on the left and right sides of the screen as shown in FIG. In such cases, conventionally, this residual portion is supplemented with another signal (for example, a single blue signal) during scan conversion. As a publicly known reference material, there is, for example, Japanese Patent Application Laid-Open No. 63-26173.

(Problem to be Solved by the Invention) However, in the projection tube of a high-definition projection TV that projects the standard television signal as described above as shown in FIG. There is a risk that burn-in steps may occur due to differences in signal levels in the signal display area.

[Means to solve the problem]

In order to solve the above problems, the high-definition projection TV of the present invention eliminates the burn-in level difference between the standard television signal display portion and the remaining portion of the supplementary signal display that may occur when displaying the standard television signal. To prevent this, the standard television signal is converted into a 9=16 horizontal signal and input to the projection tube. In other words, no residual portion is left on the image display surface of the projection tube.

[Effect]

As described above, the present invention converts the aspect ratio of a standard television signal and inputs it to the projection tube in accordance with that of a high-definition television, thereby eliminating the residual portion on the image display surface of the projection tube, thereby eliminating the burn-in level difference. I can't.

(Example〕 Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a perspective view showing the configuration of essential parts of a high-definition projection TV according to the present invention. In the figure, l indicates a projection tube of a high-quality projection TV, 2 indicates a projection lens, and 3 indicates a light flux conversion lens.

The image display surface of the projection tube l has an aspect ratio of 9:16.

The light flux conversion lens 3 has a deflection angle of the light flux in the X-axis direction that is narrower than that in the y-axis direction, so what is displayed circularly on the image display surface of the projection tube l is the light flux conversion lens 3.
When passing through the ellipse, the y-axis becomes an ellipse and is projected onto a screen (not shown). For example, an anamorphic lens is used as the light flux conversion lens, and when projecting a high-definition television signal, it is mechanically moved so that it can be removed from the optical path (
For example, make it possible to attach the arrow so that it can move to the darkness of the night).

FIG. 2 shows a schematic circuit diagram of this embodiment. The same parts as in FIG. 1 are given the same reference numerals. In the figure, 4 is a screen, 5 is a high-definition television signal input terminal, 6 is a standard television signal input terminal, 7 is a synchronization separation circuit, 8 is a signal processing circuit, 9 is a vertical deflection circuit, 10 is a horizontal deflection circuit, 11 indicates a horizontal amplitude adjustment circuit.

FIG. 3 is a diagram for explaining the state of image projection in this embodiment.

In FIG. 2, a synchronization signal is extracted from a standard television signal input from a standard television signal input terminal 6 by a synchronization separation circuit 7. The extracted vertical synchronization signal and horizontal synchronization signal are sent to a vertical deflection circuit 9 and a horizontal deflection circuit 1, respectively.
0 and drives both the vertical and horizontal deflection yokes (not shown) of the projection tube 1. The image signal output from the synchronization separation circuit 7 is input to the signal processing circuit 8, subjected to processing such as amplification, and then applied to the projection tube 1, where it is displayed on the image display surface of the projection tube 1. At this time, the horizontal amplitude adjustment circuit 11 is adjusted so that the image is displayed on the image display surface of the projection tube 1. The degree of enlargement is set to 4/3 based on the aspect ratio. Therefore, a circular image is displayed as a horizontally elongated ellipse. FIG. 3A shows this state. Next, the standard television signal image displayed on the image display surface of the projection tube 1 is focused by the projection lens 2 as described above, and the deflection angle is narrowed only in the horizontal direction by the light flux conversion lens 3, and the image is projected onto the screen 4. be projected. FIG. 3B shows this state. Of course, the degree to which the deflection angle is narrowed is
It is the reciprocal of the degree of magnification at the projection tube 1. That is, 3/
Multiply it by 4 times.

When displaying a high-definition television signal, the high-definition television signal is input to the high-definition television signal input terminal 5 in FIG. At this time, the light flux conversion lens 3 is moved and removed from the optical path. A 9:16 high-quality television signal image displayed on the projection tube 1 is focused by a projection lens 2 and projected onto a screen 4 with an aspect ratio of 9:16.

〔Effect of the invention〕

In high-definition projection TVs that can display standard TV signals with different aspect ratios, when the standard TV signal is input to the projection tube, the image is stretched horizontally to prevent residual parts from forming. There are no burn-in steps on the phosphor screen.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of main parts of an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of the embodiment, FIG. 3 is an explanatory diagram of the image projection state in the embodiment, and FIG. 4 is an explanatory diagram of the image projection state in the conventional example. 1 Projection tube 2--・------Projection lens 3...Light flux conversion lens 4---Screen IO--------Horizontal deflection circuit 11--・・−
~---------Horizontal amplitude adjustment circuit 12.13--
... Remaining part Figure 1 Figure 2 High quality Ichitate TV Gene No. 43 Aspect ratio 9:16 Conventional (JIJK O-Keru image) Explanatory diagram of the projection state of the image No. 4
surface

Claims (1)

[Claims] In a high-definition projection TV that can display a high-definition television system signal and a current standard television system signal with different aspect ratios, when projecting the current standard television system signal, on the projection tube surface. The horizontal and vertical scanning amplitudes are adjusted to make the aspect ratio equal to that of the high-definition television signal, and when projecting onto the screen, the horizontal and vertical projection angles are adjusted using a light flux conversion lens. A high-definition projection TV characterized in that the aspect ratio is returned to that of the current standard television system.