JPS6347395B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a display device, and more particularly to a projection display device that displays a large color screen using a special screen.

BACKGROUND ART In recent years, with the rapid development of video technology, there is a tendency for video technology to be used in various fields. In this case, a large screen is required when a large number of people view the content at the same time, such as in educational and conference situations. For television receivers using cathode ray tubes, the limit is around 30 inches due to the structure of the cathode ray tube, so a projection display device is used to obtain a large screen of 50 inches or 100 inches. ing.

In this case, conventionally commonly used projection display devices are equipped with three cathode ray tubes for red, blue, and green, and project the images displayed on each of the cathode ray tubes onto a screen. A large color video screen is obtained by combining color images.

However, since the above-described conventional projection display apparatus enlarges and projects the display screens of the cathode ray tubes responsible for the three primary colors onto the screen, the projected screen becomes darker as the magnification increases. In addition, in the above configuration, since a color screen is obtained by combining three primary color images displayed on three cathode ray tubes on the screen surface, color shift occurs and image quality deteriorates. The viewing angle also becomes narrow. Furthermore, the above configuration has various problems, such as the need for three cathode ray tubes, which makes the configuration complicated and extremely expensive.

DISCLOSURE OF THE INVENTION Accordingly, an object of the present invention is to provide a projection display device that is bright, does not cause color shift, has a wide viewing angle, and is simple in structure and inexpensive.

In order to achieve such an object, the present invention provides red, red,
A screen configured by arranging three types of stripe filters that transmit the three primary color lights of green and blue respectively through predetermined reflection bands that reflect three types of light having different wavelengths;
A variable light control source that scans and projects a light beam having primary color light components onto the back side of the screen, and three types of light that selectively detect three types of reflected light with different wavelengths reflected from the three types of reflection bands. A sensor is provided, and the projection light of the variable light source is varied in accordance with the corresponding three primary color signals in accordance with the outputs of the three types of optical sensors indicating the position of the scanning projection light with respect to the three types of stripe filters constituting the screen. It is something.

Therefore, in a projection display device configured in this way, unlike a conventional projection display device that simply enlarges and projects the display screen onto a screen, the three primary color lights are scanned and projected onto the screen. Since the light is selected, a bright color enlarged screen can be easily obtained by using only one variable light control source, and various excellent effects such as preventing color shift are obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a projection display device according to the present invention. In the figure, 1 is a screen, and this screen 1 has three types of stripe filters 2a, 2b, and 2c that transmit only red, green, and blue light, respectively, arranged side by side with small intervals. It has a structure. A first reflection band 3a that reflects only light having a predetermined first wavelength is provided between the stripe filters 2a and 2b.
Between the stripe filters 2c and 2c, there is a second reflection band 3b that reflects only light having a predetermined second wavelength, and further between the stripe filters 2c and 2a, there is a stripe stripe having a predetermined third wavelength. A filter 3c is provided respectively. Reference numeral 4 denotes a reflected light detection unit located on the back side of the screen 1 to detect reflected light from each of the reflective bands 3a to 3c, and selectively detects only the first wavelength light reflected from the first reflective band 3a. a second optical sensor 5b that selectively detects only the second wavelength light reflected from the second reflective band 3b; and a second optical sensor 5b that selectively detects only the second wavelength light reflected from the second reflective band 3b; and a third photosensor 5c that selectively detects only the three wavelengths of light.
Reference numeral 6 projects a light beam having three primary color light components of red, green, and blue onto the back surface of the screen 1, and scans the entire surface in the direction in which the stripe filters 2a to 2c are arranged in parallel, and the amount of projected light can be varied. It is a variable light source. The variable light control source 6 is composed of a monochrome cathode ray tube 7a having a fluorescent surface that emits light containing three primary color components, and a lens 7b that projects the display brightness of the cathode ray tube 7 onto the back surface of the screen 1. ing. 8 is a dimming control section,
Each color signal of the three primary colors included in the video signal is
By selecting according to the outputs of the third optical sensors 5a to 5c, it is supplied to the variable light control source 6 as a light control signal. Note that the variable light control source 6 scans the light beam in accordance with horizontal and vertical synchronization signals included in the video signal.

In the projection display device configured in this way, when the power switch is turned on while receiving a video signal, the cathode ray tube 7a of the variable light control source 6 is deflected and driven in accordance with the synchronization signal included in the video signal. As a result, the bright spot becomes the cathode ray tube 7a.
scan the display surface. Then, this bright spot is projected onto the back surface of the screen 1 by the lens 7b, and the back surface of the screen 1 is scanned. Here, when _the beam-shaped projection light emitted from the variable light control source 6 is irradiated onto, for example, the stripe filter 2c ₂ , only the blue light component is transmitted to the front of the screen 1 via the stripe filter 2c 2. do. Therefore, the viewer sees the projected portion of the light beam A of the filter _2c2 emitting blue light.

Next, when the projected portion of the light beam A moves from the stripe filter 2c ₂ to the stripe filter 2b ₂ , in order to irradiate the third reflector 3c during this movement process, the above-mentioned Only the light having wavelength 3 is reflected and supplied to the reflected light detection section 4. Here, since the reflected light detection section 4 is configured such that only the third optical sensor 5c detects only the light having the third wavelength, when the light beam A crosses the third reflection zone 3c, this Third optical sensor 5c
Output is generated only from Therefore, the output signal of this third photosensor 5c is the irradiation position of the light beam A,
In other words, it is an irradiation position signal indicating that the light beam A is irradiating between the stripe filter 2c ₂ and the stripe filter 2b ₂ . When the output signal from the third photosensor 5c is supplied to the dimming control unit 8, the dimming control unit 8 directs the light beam A to the part of the stripe filter that transmits the green color. Based on this determination result, the green signal included in the video signal is selected and supplied to the variable light control source 6 as a light control signal. Therefore,
The variable light source 6 controls the light beam A emitted at that point in time.
The amount of light is emitted as a value corresponding to the level of the green signal in the corresponding part of the video signal,
This light beam A whose light amount is controlled is irradiated onto the stripe filter _2b2 , and since only the green light included in this light beam A passes through the stripe filter _2b2 , this portion is at the level of the green component of the color signal. It will be in a state where it emits light with an intensity that corresponds to the amount of light.

Next, when the irradiated portion of the light beam A moves to the stripe filter 2a ₂ , it crosses the second reflection band 3b during the movement process, so that the light having the second wavelength reflected at this time becomes the second wavelength. It is detected by the optical sensor 5b and an output is generated. Since the output signal of the second optical sensor 5b is supplied to the dimming control section 8, the dimming control section 8 selects the red signal component at that point in time and supplies it to the variable dimming source 6. .
Therefore, the variable light control source 6 emits a light beam A with an amount of light corresponding to the level of the red signal, and irradiates the stripe filter _2a2 . As a result, an amount of red light corresponding to the level of the red signal included in the video signal is transmitted from the stripe filter 2a ₂ and radiated to the front of the screen. A state is reached in which light is emitted corresponding to the red signal level of the video signal.

When the entire surface of the screen 1 is scanned by the light beam A while performing these operations sequentially, a large color screen corresponding to the input video signal is projected onto the screen 1. In this case, instead of projecting a three-primary color screen and compositing it on the screen surface, the scanning projection position of the light beam onto the screen where the stripe filters are arranged in parallel is determined by the type of each stripe filter. The projection light beam is determined based on the type of reflected light reflected from the reflective bands provided in parallel to each stripe filter, and the projection light beam is determined according to the level of the color signal selected according to the determination result. Since the light beam scanning portion of each stripe filter is seen to be sequentially emitted at a level corresponding to the color signal, color shift does not occur. Further, by providing, for example, a Fresnel lens 9 on the front side of each stripe filter, a clearer color screen can be obtained.

In the above embodiments, a monochrome cathode ray tube is used as a variable light source that modulates a light beam having three primary colors and scans and projects the light onto a screen. However, the present invention is not limited to this. It goes without saying that this is not the case, and that other configurations may be used as long as similar functions can be obtained.

As described above, according to the projection display device according to the present invention, a large and bright color screen can be easily obtained, and the occurrence of color shift can be prevented. In addition, the present invention does not require three color cathode ray tubes that handle three primary color screens as in the past, and can provide a color screen with one variable light source, simplifying the structure. It has various excellent effects such as cost reduction.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a projection display device according to the present invention. 1... Screen, 2a, 2b, 2c... Stripe filter, 3a, 3b, 3c... First to third reflection bands, 4... Reflected light detection section, 5a to 5c...
1st to 3rd sensors, 6... variable light control source, 7a...
Braun tube, 7b...lens, 8... dimming control unit, 9... Fresnel lens.

Claims (1)

[Claims] 1. A screen configured by three types of stripe filters that transmit the three primary color lights, respectively arranged in parallel via reflection bands that respectively reflect three different types of light determined in advance;
It has a variable light control source that scans and projects a light beam having primary color light components onto the back side of the screen, and a reflected light detection unit that determines the type of reflected light of the light beam reflected from the three types of reflection bands. . A projection display device, wherein the variable light control source displays a color screen by adjusting the brightness according to a color signal selected according to the discrimination output of the reflected light detection section.