KR20040019528A - Apparatus and method for controling light screen of projection display system - Google Patents

Abstract

PURPOSE: A device and a method for controlling brightness of a screen of a projective display device are provided to express various images, and display a bright image by increasing the brightness of a picture. CONSTITUTION: If R, G, and B video signals are inputted, a video brightness sensing unit(20) senses the brightness of the video signals. If the inputted video is bright, a light source controller(18) increases a driving power of a lamp for increasing the brightness of the lamp and a video signal controller(19) increases a driving voltage of pixels of a display device(14). If the inputted video is dark, the light source controller decreases the driving power of the lamp for decreasing the brightness of the lamp, and the video signal controller decreases the driving voltage of the pixels of the display device.

Description

Apparatus and method for controling light screen of projection display system}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device, and more particularly, to a screen brightness control device and a method of a projection display device which obtains a bright and clear image by sensing screen brightness according to an image signal and adjusting brightness of each pixel and a light source. .

Recently, a flat panel display that has a large thickness and realizes a large screen has been attracting attention by replacing a conventional CRT display having a limited screen size and a large system size.

Such display devices include LCDs, PDPs, projection systems, and the like. Currently, display methods using projections for large screens have become mainstream.

In general, an LCD projection system projects light from a light source onto an LCD panel, and projects an image of the LCD panel onto a screen using a projection optical system to view an image formed on the screen.

1 is a view showing the configuration of a conventional projection display device.

Referring to FIG. 1, the light emitted from the lamp 1 is collected in one direction by the reflector 2 and travels and is irradiated to the LCD panel 4 by the illumination optical system 3.

In addition, the LCD panel 4 displays an image by adjusting the amount of light by an electrical signal of the image signal controller 9 that receives and processes the image signal.

The displayed image is magnified and projected onto the screen 6 by the projection optical system 5 so that the user can view the image from the front or the rear of the screen 6.

On the other hand, the lamp is started by operating the power controller 8 which controls the power supply of the projection display device.

In the projection display device as described above, the lamp 1, which is a light source, is applied with a constant voltage and current to emit a certain amount of light and adjusts the transmittance at each pixel of the LCD panel 4 according to an image signal. The brightness is adjusted and the overall image is realized.

However, such a projection display device does not change the brightness of the light source even when the image signal shows a bright screen or a dark screen, and the brightness is adjusted by the transmittance adjustment only on the LCD panel, which is a display device, so that a dark screen such as a night scene is displayed. When displaying, the LCD panel does not completely block light, so light leaks and the screen looks blurry, gray scale is not accurate, and contrast is deteriorated.

In addition, when displaying a bright screen, there is a limitation in brightness, and the brightness of the screen gray is saturated, resulting in a decrease in contrast of the image and a decrease in the dynamic range of the image.

Accordingly, an object of the present invention has been made in view of the above-mentioned problems of the prior art, by detecting the screen brightness control state of the image signal to improve the screen brightness, contrast enhancement, An object of the present invention is to provide an apparatus and method for effectively controlling a projection display screen brightness of dynamic range enhancement.

1 is a view showing a conventional projection display device

2 is a diagram illustrating an apparatus for controlling screen brightness of a projection display device according to the present invention.

3 is a timing diagram of image brightness information of a screen brightness control device of a projection display device according to FIG. 2;

4 is a flowchart illustrating a method of controlling screen brightness of a projection display device according to the present invention.

5 is a flowchart illustrating a flow of screen brightness determination adjustment according to FIG. 4.

6 illustrates an embodiment of an apparatus and method for controlling screen brightness of a projection display device according to the present invention.

* Description of the symbols for the main parts of the drawings *

11 light source 12 reflector

13 illumination optical system 14 display device

15: projection optical system 16: screen

17: power controller 18: light source controller

19: Image signal controller 20: Image brightness detector

21: image brightness information storage unit

According to one aspect of the present invention for achieving the above object, in a projection display device using a light source, the brightness signal of the input image signal or the R, G, B signal is analyzed and the input according to a predetermined criteria And a sensing unit for determining the screen brightness of the image signal, a storage unit for storing the image signal analyzed by the sensing unit, and a pixel driver for driving each pixel according to the brightness of the stored image signal. do.

Preferably, the sensing unit analyzes the input image signal for each pixel to determine the brightness state, and the storage unit stores the image signal analyzed by the sensing unit for each pixel unit.

Another aspect of the present invention for achieving the above object is a projection display device using a light source, which analyzes the brightness signal or R, G, B signal of the input image signal and the corresponding input by the predetermined criteria A detector for determining the screen brightness of the image signal, a storage unit for storing the image signal analyzed by the detector, and a light source driver for controlling the brightness of the entire screen by adjusting the light quantity of the light source according to the brightness of the stored image signal Characterized in that consisting of.

According to another aspect of the present invention for achieving the above object, in the method of controlling the screen brightness of a projection display device using a light source,

The method may include determining a brightness state of the input R, G, and B image signals based on a predetermined reference, and controlling the amount of light of a pixel according to the brightness of the image signal.

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a diagram illustrating a screen brightness control device of a projection display device according to the present invention.

Referring to FIG. 2, a screen brightness control apparatus of a projection display device according to the present invention includes a light source 11, a reflector 12 that collects and moves light from the light source 11 in one direction, and the light source 11. And a display element 14 for displaying an image by an image signal, a projection optical system 15 for magnifying and projecting the image of the display element 14, and a screen 16 for forming an image.

In addition, the operation driver of the projection display device configured as described above is a power controller 17 connected to a power source and supplying power to each circuit unit, and supplying power to the light source 11 and controlling the brightness of the light source 11. A light source controller 18, an image signal controller 19 that receives an image signal, processes an image signal, and transmits the image signal to the display element 14, and an image brightness detector 20 that detects the brightness of the image signal. ) And an image brightness information storage unit 21 for storing the image brightness information.

In the operation of the screen brightness control device of the projection display device configured as described above, the light emitted from the light source 11 is collected in one direction by the reflector 12.

The advanced light is irradiated to the display element 14 by the illumination optical system 13.

The display element 14 displays an image by an image signal of a signal processing unit. As the display element 14, elements such as a transmissive LCD panel, a reflective LCD panel, and a digital micro mirror device (DMD) are used.

Subsequently, the image implemented in the display element 14 is enlarged and projected by the projection optical system 15 to form an image on the screen 16, and the user views the screen from the front or the rear of the screen 16.

On the other hand, the power controller 17 is connected to the external power supply to supply power to operate the entire projection display device.

The light source controller 18 supplied with power from the power controller 17 supplies a voltage and a current to the light source 11 to activate the light source 11.

The input image signal is analyzed by the image brightness sensor 20 to detect the brightness of the video signal.

That is, the brightness of the image is analyzed based on the brightness determination criteria by extracting the image brightness through the Y signal or the R, G, and B signals which represent the brightness among the image signals constituting the image.

In addition, by analyzing the brightness state of each pixel of the image from the image signal of the image to determine the bright area, the dark area and the boundary area in the image to generate the signal information for driving the respective pixels.

For example, in NTSC, set the level for the Y signal, which is the luminance signal, so that 80 or more bright screens, 60 or more bright screens, mid-level normal screens, 40 or less dark screens, and 20 or less are set based on 100. It can be classified as a dark screen.

According to the classification state of the image, the light source 11 and the display element 14 are adjusted to be displayed appropriately for the brightness.

The brightness information of the image analyzed by the image brightness sensor 20 is recorded and stored in the image brightness information storage 21. The overall brightness information of one image and brightness information of each pixel of the image are recorded and stored. The video signal is transmitted to the controller 19.

When the video brightness information storage unit 21 implements a moving image, the image brightness information storage unit 21 receives a continuous image signal, records and stores the brightness information of one image, transmits the brightness information of the next image, and receives the brightness information of the next image. Clears the brightness information of the previous image and saves a new record.

As a result, the brightness information of the image of one frame is sequentially recorded and stored, and the information is transmitted.

3 is a timing diagram of an image brightness information storage unit of the screen brightness control apparatus of the projection display device of FIG. 2.

As shown, in the case of displaying an image of one frame at 60 Hz, after recording and storing the brightness information of the image of one frame for 1/60 second, the image brightness information of the next frame is sequentially recorded and stored.

Then, the image brightness information storage unit 21 records brightness information on an input image signal using a memory device such as a RAM or a flash memory, and the image signal controller 19 stores the image brightness information storage unit. At 21, the image signal information is received to process the image signal, and each pixel of the display element 14 is driven to display an image of the image signal.

In this case, the brightness information of the image signal corresponding to each pixel of the display element 14 is not the first input image signal, but is determined by the image brightness sensor 20 and optimized brightness recorded and stored in the image brightness information storage unit 21. Information.

That is, brightness information is added to the first video signal to drive each corresponding pixel in accordance with the corrected video signal.

4 is a diagram illustrating a method of controlling screen brightness of a projection display device according to an exemplary embodiment, in which R, G, and B image signals are input (S11).

Then, the brightness of the input video signal is determined by a predetermined algorithm (S12).

As a result of the determination, when the input image is a bright image, the driving power of the lamp is increased to increase the brightness of the lamp, and then the brightness of the entire image is increased (S13 to S15).

Meanwhile, as a result of the determination, when the input image is a dark image, the driving power of the lamp is reduced to reduce the brightness of the lamp, and then the brightness of the entire image is reduced (S16 to S18).

FIG. 5 is a flowchart illustrating brightness of pixels by an arbitrarily determined algorithm according to FIG. 4. When R, G, and B image signals are input, the brightness is determined (S21 to S22).

The brightness judgment is to set the step to the Y signal, which is the luminance signal, and set it to 80 or more based on 100, the bright image, the 60 or more slightly bright image, the middle stage to the normal brightness image, 40 or less, slightly dark image, 20 or less If the bright image is classified into a dark image, the driving voltage of the pixel is increased to increase the amount of light in the pixel, and the brightness of the pixel is increased to increase the image brightness of the pixel configuration (S23 to S26).

As a result of the determination, if the image is a little bright, the driving voltage of the pixel is slightly increased, the light quantity of the pixel is slightly increased, and if the brightness of the pixel is slightly increased, the image brightness of the pixel configuration is slightly increased (S27 to S30). .

In this manner, the image brightness of each pixel configuration may be controlled according to the normal brightness (S31 to S34), slightly dark brightness (S35 to S38), and dark brightness (S39 to S42).

6 is an embodiment of the screen brightness control device and method of the projection display device according to the present invention, when displaying an image consisting of the sun, trees and shadows, and determines the brightness state for the entire screen brightness and brightness for each pixel The state is corrected to correct the brightness of a part of the image formed by the pixel. In the illustrated screen, since the sun is a bright screen, when the corresponding pixel of the display device constituting the sun is driven, the amount of light is increased.

In addition, since the shadow is a dark part, when driving the corresponding pixel of the display device forming the shadow, the amount of light is driven to be smaller than the initial image signal.

In addition, a bright part is displayed brighter and a dark part is darker in one screen, so that the contrast is increased by increasing the contrast and the dynamic range of the image is improved by increasing the level of displaying the brightness.

As described above, the present invention realizes a brighter image brighter and darker the darker screen, thereby enabling various and richer image expressions, and increasing the luminance of the image, thereby displaying a brighter image.

In addition, the present invention can increase the contrast of an image to display a clear image.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

Claims (5)

In a projection display device using a light source, A detector configured to analyze the brightness signal of the input image signal or the R, G, and B signals and determine the screen brightness of the corresponding input image signal based on a predetermined criterion; A storage unit for storing the image signal analyzed by the detection unit; And a pixel driver for driving each pixel according to the brightness of the stored image signal. The method of claim 1, And the sensing unit analyzes the input image signal for each pixel to determine a brightness state. The method of claim 1, And the storage unit stores the image signal analyzed by the detection unit in units of pixels. A detector configured to analyze the brightness signal of the input image signal or the R, G, and B signals and determine the screen brightness of the corresponding input image signal based on a predetermined criterion; A storage unit for storing the image signal analyzed by the detection unit; And a light source driver configured to adjust the brightness of the entire screen by adjusting the light amount of the light source according to the brightness of the stored video signal. In the method of controlling the screen brightness of a projection display device using a light source, Determining a brightness state of the input R, G, and B image signals by a predetermined reference; And controlling a light amount of a pixel according to the brightness of the image signal.