JPH03108982A - Projection type video display device - Google Patents

Abstract

PURPOSE:To reduce power and to prolong the life of a cathode ray tube by reproducing inputted video signals as color pictures while sharing a white signal, which easily gets high luminance, by the four cathode ray tubes by colors adding a cathode ray tube exclusive for white color. CONSTITUTION:Inputted red, green and blue video signals 1a-1c are respectively supplied to operational amplifiers 5a-5c and to a minimum level signal detection circuit 2 as well and in the minimum level signal detection circuit 2, a video signal 3d at the minimum level selected out of the video signals 1a-1c is supplied through a picture output circuit 6d to a white high luminance cathode ray tube 7d as the white video signal component of the video signals 1a-1c. Then, the white picture is reproduced. On the other hand, in the operational amplifiers 5a-5c, a video signal 3a at the minimum level attenuated by an attenuator 4 is subtracted from the respective input video signals 1a-1c, outputted and supplied to respective single color high luminance cathode ray tubes 7a-7c. Thus, energy consumption is reduced and the life of projective video display device can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a projection type image display device using a high-brightness cathode ray tube.

[Conventional technology]

Three single-color high-brightness cathode ray tubes corresponding to each color of red, green, and blue are arranged in-line or in a delta shape, and the image of each color reproduced on each of the cathode ray tubes by the input video signal of each color is reproduced using a dedicated magnifying lens. It was projected onto a screen and combined into a color image.

[Problem to be solved by the invention]

Images reproduced by three cathode ray tubes corresponding to each color (red, green, and blue) are enlarged and projected onto a screen using optical lenses, so projection type cathode ray tubes are required to have high brightness.

As a result, compared to direct-view cathode ray tubes, they required operation at higher voltages and larger amounts of power, generated more heat, and were subject to significant aging due to long-term operation at high temperatures, resulting in short lifespans.

The present invention aims to extend the life of the projection type cathode ray tube while reducing the voltage and power applied to the projection type cathode ray tube while obtaining images of the same brightness as before.

[Means to solve the problem]

The minimum level signal of the video signals of each color, red, green, and blue, is used as a component of a white video signal common to the video signals of each color, and a part of the same white video signal component is subtracted from the video signal of each color, In addition to supplying the signals to the cathode ray tubes corresponding to each color, a portion of the same white video signal component is also supplied to the high-brightness cathode ray tubes dedicated to white, and the red and red images reproduced by each of the four cathode ray tubes are
It is a projection type image display device that projects green, blue, and white monochromatic images onto a screen using respective magnifying lenses.

[Effect]

Red, green, and blue video signals 18 to 1 forming a color video
If the levels of c are expressed as Er, Eg, and Eb, respectively,
When the same image is white, it is expressed as Erm EgtsuEb.

In color images containing white components, Er, Eg, E
Letting the minimum level signal of each video signal of b be Eui,
Each of the red, green, and blue video signals can be expressed as Erm Ew+ΔR El Ew+ΔG Ebm Ew+ΔB, and any one of ΔR2ΔG1ΔB is zero.

That is, among each color signal component, the component Ew with the lowest level is a white signal component, and the residual component obtained by subtracting the white signal component from each color signal component is the pure color component ΔR1ΔG1ΔB.
It is.

The brightness of the composite of red, green, and blue video signals at this time is Y= Er+ Eg+ Ebm 3Ew+ΔR+ΔG+
It can be expressed as ΔB.

The minimum level signal is detected from the input red, green, and blue video signals 1tt-1c.

In the minimum level signal detection circuit shown in Figure 2, the input red, green, and blue video signals! From a to IC, level comparator 2a
The level comparator 2b compares the levels of the red video signal la with respect to the green video signal 1b, the green video signal 1b with respect to the blue video signal 1c, and the blue video signal 1c with respect to the red video signal 1a. 2m to 2p are obtained.

The level comparison signals 2m to 2p obtained from the red, green, and blue video signals 1tt-1c are calculated by a logic circuit composed of gate circuits 2d to 2L, and the red, green, and blue video signals are generated! Signals 29 to 2S indicating that any one of α to IC is at the minimum level
Output.

The red, green, and blue minimum level signals 29 to 2S close any of the corresponding switch circuits 3a to 3C, and output the minimum level video signal 34.

The minimum level video signal 34 selected from the red, green, and blue video signals 1a-1c is the white video signal component Ew, so this signal is amplified and supplied to the white high-brightness cathode ray tube 7d, and the white video signal 34 is a white video signal component Ew. Reproduce the image.

White video signal component E supplied to the white cathode ray tube 7d
By subtracting 173 of w from each of the red, green, and blue video signals 1a to lc, the corresponding monochrome cathode ray tube 74 is obtained.
~7c to reproduce the corresponding monochromatic image.

The level relationship of the video signals supplied to the monochrome high-brightness cathode ray tubes 7a to 7c of each color, including the white monochrome high-brightness cathode ray tube 7d, is expressed as Er'-2Etrr73+ΔR Eg'-2Evt/3+ΔG Eb'-2Ew/3+ΔB Bur-Ew. The brightness of the combined image at this time is Y” m
Er' + Eg' + Eb" + Ea-EEw
+ΔR+ΔG+ΔB, which is the input video signal! The same image as α~lc can be reproduced.

As described above, by reproducing images that are reproduced by the three high-intensity cathode ray tubes of red, green, and blue with four high-intensity cathode ray tubes including white, the burden on each cathode ray tube can be reduced.

Therefore, the power consumption and applied voltage can be reduced by the amount corresponding to the reduction in brightness of each cathode ray tube corresponding to each color of red, green, and blue, and the heat generation of each cathode ray tube and the deterioration caused by the heat generation can be reduced. .

[Example] Input red, green, and blue video signals! amlc to the operational amplifiers 5a to 5C, respectively, and the same video signal 1
a~IC is branched and also supplied to the minimum level signal detection circuit 2.

In the minimum level signal detection circuit, the level comparators 24 to 2C shown in Fig. 2 compare the signal levels of the input red, green, and blue video signals 1a to IC and output them as level comparison signals 2m to 2p. do.

The mutual level comparison signals 2m to 2p of the red, green, and blue video signals 1a to 1c are calculated by a logic circuit composed of gate circuits 2d to 2L, and one of the red, green, and blue video signals 14 to IC is calculated. Signals 29 to 2S indicating the minimum level are output.

The red, green, and blue minimum level signals 29 to 2S close any of the corresponding switch circuits 3a to 3C, select one of the input red, green, and blue video signals 1a to IC, and switch to the minimum level signal. It is output as a video signal 34.

The minimum level video signal 34 selected from the red, green, and blue video signals 1a-1c is used as the white video signal component of the video signals 1a-1c, and the video signal 34 is outputted as a white video signal component through the video output circuit 6d. The light is supplied to a high-intensity cathode ray tube 7d to reproduce a white image.

The minimum level video signal 34 outputted by the minimum level signal detection circuit is reduced to a level of 173 by the attenuator 4, and is then transmitted to the operational amplifiers 54 to 173 which supplied the input video signals 1a-1c.
Supplied to all 5C negative inputs.

The operational amplifiers 5α to 5c subtract the minimum level video signal 34 attenuated to 173 by the attenuator 4 from the red, green, and blue input video signals 1a to IC, respectively, and output the subtracted video signals 34 for red, green, and blue, respectively. Video output circuits 6a~ corresponding to each color of blue
6C, each monochrome high brightness cathode ray tube 7a~
Supply to 7C.

Each CRT 7 corresponds to red, green, blue, and white colors.
a to 7d are arranged in a convex shape or a diamond shape, and the cathode ray tube 7
Images of each color reproduced by α to 7d are projected by respective magnifying lenses to reproduce a color image on the screen.

In reproducing the input video signal as a color image,
By dividing and reproducing the white signal, which tends to have high brightness, among four cathode ray tubes, including a white-only cathode ray tube, the brightness of each cathode ray tube can be kept low.

In addition, in the pseudo-color method, which reproduces a color image on a screen by combining two-color projected images, called the Land color phenomenon, a monochromatic high-brightness cathode ray tube corresponding to the two colors and a method similar to the above are used. The same effect as described above can be obtained by dividing and reproducing a white image using a white-only high-brightness cathode ray tube that reproduces a white image using a white image signal.

The present invention can be used as a front projection television device in which images projected onto a screen are directly observed using a magnifying lens, or by reflecting the output light of the magnifying lens with a plane mirror or a concave mirror to display images projected from the back of the screen. It is also possible to use a rear projection type television device in which the screen is viewed from the front.

Further, the present invention can be implemented not only in a television device but also in a video monitor for observing a video signal and a display monitor as a display device for a computer.

(Effects of the Invention) As described above, by reproducing the image reproduced by three projection type monochrome high brightness CRTs using four projection type single color high brightness CRTs, the brightness shared by each CRT can be reduced.
Since power consumption is reduced, the amount of heat generated is also reduced, which not only simplifies measures for heat dissipation, but also suppresses deterioration of the characteristics of each cathode ray tube, resulting in a long-life device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the present invention, and FIG. 2 is an electrical circuit diagram of the minimum level signal selection circuit of FIG. 1. In the diagram! a is a red video signal, 1b is a green video signal, lc is a blue video signal, 2 is a minimum level signal detection circuit, 2a to 2c are level comparators, 2d to 2L are logic operation circuits, 2m to 2n are level comparison signals, 29 to 2s are red, green, and blue minimum level signals, 3a to 3c are analog switch circuits, and 3d
is the minimum level signal, 4 is an attenuator, 54 to 5c are operational amplifiers, 64 to 6c are video output circuits, 7a is red, 7b is green, 7c is blue, and 7d is white projection type monochrome high-brightness cathode ray tube. It is.

Claims (3)

[Claims] (1) In a projection display device that reproduces a monochromatic image on a phosphor screen using a monochromatic high-brightness cathode ray tube and projects it onto a screen using a magnifying lens to create a color image, the minimum level signal of each input color image signal is used as a white image signal. , subtracting a part of the same white video signal from the video signal of each color and supplying the same to a cathode ray tube corresponding to each color, and supplying a part of the same white video signal to a high brightness cathode ray tube exclusively for white;
A projection type image display device characterized in that each monochromatic image including white reproduced by each of the above-mentioned cathode ray tubes is projected onto a screen using each magnifying lens. (2) Projection according to claim (1), characterized in that each monochromatic image reproduced by red, green, and blue monochromatic high-brightness cathode ray tubes and a white dedicated high-brightness cathode ray tube is projected onto a screen using respective magnifying lenses. type video display device. (3) The projection type image display device according to claim (1), wherein the two-color monochrome high-intensity cathode ray tube and white monochrome images based on the Land color phenomenon are projected onto the screen by respective magnifying lenses.