KR20040063553A - A projection image display system for automatically controlling brightness and method thereof - Google Patents

Abstract

PURPOSE: A projective image display system having an automatic luminance adjustment function and a method therefor are provided to automatically correct luminance difference generated in an image projected by external cause. CONSTITUTION: A screen(10) has a plurality of optical sensors(16), a microcomputer(17) and a transmitting unit(18). The optical sensors(16) measure a luminance level of light projected on the screen(10). The microcomputer(17) calculates coordinates on the screen(10) with respect to the optical sensors(16), compares luminance levels transmitted from the optical sensors(16), and calculates luminance difference generated in each coordinate. The transmitting unit(18) transmits the coordinates with respect to the optical sensors(16) and data about the luminance difference in each coordinate to a projector(20). The projector(20) has a receiving unit(26) and a microcomputer(28). The receiving unit(26) receives the coordinates and the data about the luminance difference transmitted from the transmitting unit(18) of the screen(10). The microcomputer(28) compensates the luminance of image signal, to be outputted to a position in which the luminance difference is generated, on the basis of the coordinates and the data about the luminance difference.

Description

Projection type image display system having automatic brightness adjustment function and method thereof {A PROJECTION IMAGE DISPLAY SYSTEM FOR AUTOMATICALLY CONTROLLING BRIGHTNESS AND METHOD THEREOF}

The present invention relates to a projection type image display system having an automatic luminance adjustment function and a method thereof, and more particularly, to a projection type image having a function of automatically correcting a luminance difference in an image projected by an external factor. A display system and method thereof are provided.

Recently, with the development of the information industry, the demand for a video display device capable of displaying a large screen image is increasing. As such, a projection image display device is widely used as an image display device capable of displaying a large sized image, and an LCD projector is particularly preferred. In addition to these applications, such LCD projectors are increasingly being used as display devices for home digital TVs.

However, in the conventional image display device, when light leaks into the screen due to some external factor, a luminance difference occurs in the projected image, and thus the brightness of the displayed image is not uniform.

1 illustrates a phenomenon in which a luminance difference occurs in a projected image due to light leaking from the outside during image projection in a conventional LCD projection system. Referring to the left figure of FIG. 1, external light is leaking into the lower portion of the screen 10. Due to this, as shown in the right figure of FIG. 1, the lower portion 14 of the screen from which light leaks from the outside appears brighter than the upper portion 12, which is not bright, so that the brightness of the image projected on the screen is not uniform throughout. Will not. As such, when the brightness distribution of the image is not uniform, the image quality characteristics of the image are not normally displayed, and the viewer's eyes are easily tired due to the luminance difference of the image. In view of the fact that the projection type image display device is widely used for presentations at seminars and the like, the above problem becomes more serious.

Therefore, in the projection type image display device, when light leaks in due to external factors, there is a need for a method and apparatus for reducing the luminance of a corresponding portion so that an image having an original uniform luminance is projected onto a screen.

Therefore, in order to overcome the above problems, the present invention recognizes a corresponding area when light leaks into the screen due to external factors, and compensates luminance in the area by circuit to display an image of uniform brightness. It is an object of the present invention to provide a projection type image display system.

In addition, the present invention provides a luminance of a projection type video display system that recognizes a corresponding area when light leaks into the screen due to an external factor, and displays an image of uniform brightness by compensating circuit luminance in the area. It is an object to provide an adjustment method.

Other objects and advantages other than the above objects and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

1 is a view showing a phenomenon in which a luminance difference occurs in a projected image due to penetration of light from the outside during image projection in a conventional LCD projection system.

2 is a diagram schematically showing a configuration of an LCD projection system according to the present invention.

3 is a schematic diagram of a configuration of an LCD projection system according to the present invention;

4 is a view showing an example in which light penetrates from outside to a part of a screen in the LCD projection system according to the present invention.

5 is a view for explaining a method of adjusting the brightness of an image signal when light penetrates from the outside into the lower part of the screen according to the preferred embodiment of the present invention.

6 is a view for explaining a method of adjusting the brightness of an image signal when light penetrates from the outside in the upper right side of the screen according to another preferred embodiment of the present invention.

7 is a view for explaining a method of adjusting the brightness of an image signal when light penetrates from the outside with a constant slope in the upper right side of the screen according to another preferred embodiment of the present invention.

8 is a flowchart illustrating a luminance adjustment algorithm of an image signal in the LCD projection system according to the present invention.

Description of the main parts of the drawing

10: screen 16: light sensor 17: microcomputer

18: transmitter 20: projector 26: receiver

27: video signal processor 28: microcomputer 29: LCD driving circuit

The projection image display system according to the first aspect of the present invention comprises a screen and a projection image display device. The screen is generated at each coordinate by comparing a plurality of light sensors for measuring the brightness level of the light projected on the screen with the coordinates on the screen for the light sensors, and comparing the brightness levels transmitted from the light sensors And a transmitting unit for transmitting the coordinates transmitted from the first microcomputer and data relating to the luminance difference in each coordinate to the projection image display device. The projection image display device may further include a receiver that receives data about coordinates transmitted from a transmitter of the screen and luminance differences at respective coordinates, and data about coordinates transmitted from the receiver and luminance differences at each coordinate. A second microcomputer for compensating for the luminance of the video signal to be output at the position where the luminance difference occurs is provided.

In a preferred embodiment of the above feature, the first microcomputer calculates the luminance difference by setting the lowest luminance level among the luminance levels transmitted from the plurality of optical sensors as a reference level.

Further, in a preferred embodiment of the above feature, the second micom converts coordinate data transmitted from the transmitting unit of the screen into pixel coordinates corresponding to the video display device.

According to a second aspect of the present invention, there is provided a method for automatically adjusting brightness of a projection type image display system, the method comprising: measuring, at a plurality of optical sensors mounted on the screen, a brightness level of a projected image; Calculating a luminance difference generated at each coordinate by comparing the luminance level measured by the optical sensor, and transmitting the calculated coordinates and data on the luminance difference at each coordinate to the projection image display device. Transmitting, receiving, by the video display device, data relating to coordinates and luminance differences at each coordinate, from the screen, and based on the received coordinates and data relating to luminance differences at each coordinate, Compensating for the luminance of the video signal to be output at the position where the difference occurs.

According to the characteristics of the present invention, when light leaks into a part of the screen due to an external factor, the luminance of the corresponding part is reduced to display an image having a uniform brightness on the screen.

Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to FIGS. 2 to 8.

2 and 3 schematically show the configuration of the LCD projection system 100 according to a preferred embodiment of the present invention.

2 and 3, the LCD projection system 100 includes a screen 10 and an LCD projector 20. The screen 10 calculates a plurality of optical sensors 16 mounted on the screen to measure the luminance of the projected image, coordinates on the screen for the optical sensors, and calculates the luminance level output from the optical sensors. A microcomputer 17 for comparing the luminance difference at each coordinate by comparison, and a transmitter 18 for transmitting the coordinates calculated at the microcom and data of the luminance difference occurring at each coordinate to the projector 20. Here, the optical sensor 16, as shown in Figure 4, it is preferable that x pieces are arranged in the X-axis and Y-axis direction in the X-axis direction of the screen so that X x Y optical sensors are arranged uniformly.

In addition, the LCD projector 20 is a receiver 26 for receiving data about the coordinates transmitted from the screen 10 and the luminance difference in each coordinate, and processes the image signals of the R, G, B to be projected on the screen An image signal processor 27, a microcomputer 28 that controls each component of the projector and adjusts the brightness of the image signal output from the image signal processor 27 based on the data transmitted from the receiver. LCD driving circuit 29 for driving the LCD in response to the control signal transmitted from the.

When the coordinates on the screen of the light sensors and the luminance difference generated at each coordinate are transmitted from the screen 10 to the projector 20, the projector's microcomputer 28 emits luminance for each coordinate based on the coordinates and luminance difference. Generates a compensated video signal. Here, the data transmission method between the screen 10 and the projector 20 may be either wireless or wired.

4 illustrates an example in which light penetrates from a part of a screen in a preferred embodiment according to the present invention. As shown in the figure, x optical sensors 16 in the horizontal axis direction and y optical sensors 16 in the vertical axis direction are arranged in the screen 10 so that the X x Y optical sensors are uniformly and densely arranged.

Hereinafter, a method of calculating coordinates on the screen for the optical sensors and a method of calculating a luminance difference at each coordinate will be described with reference to FIG. 4.

First, the method of calculating the coordinates on the screen of the optical sensor will be described. The positions of the respective optical sensors shown in FIG. 4 are converted into coordinates on the screen by the following equation (1) in the microcomputer 17.

Here, n: rank of the optical sensor in the horizontal axis direction

m: rank of the optical sensor in the longitudinal direction

Therefore, since the optical sensor shown in black in FIG. 4 is located at A ″ -th in the horizontal axis direction and B'-th in the vertical axis direction, it is calculated as (A ″ / x, B '/ y) coordinates in the microcomputer 17. do. In this way, the microcomputer 17 converts the positions of all the optical sensors mounted in the screen to one-to-one coordinates.

Next, a method of measuring the luminance difference in the calculated coordinates will be described.

First, in order to measure the brightness of light projected onto the screen 10, a full white pattern is projected from the projector 20 onto the screen. In this case, the photosensors 16 measure the brightness of the light projected to the corresponding position, and transmits it to the microcomputer 17. The microcomputer 17 compares the luminance levels output from the optical sensors 16 and calculates a luminance difference at each coordinate. In this case, the reference luminance level becomes the lowest luminance level among the luminance levels transmitted from the photosensors.

5 to 8 are diagrams for explaining a method of adjusting the luminance of an image signal in the projector 20 on the basis of the coordinates of the optical sensor transmitted from the screen 10 and the data on the luminance difference in each coordinate. One graph.

5 is a graph illustrating a method of adjusting the brightness of an image signal when light penetrates from the outside in the lower portion of the screen 10 according to the preferred embodiment of the present invention. The graph shown on the left side of FIG. 5 shows the original screen and the light leaking portions on the screen, respectively. Here, the part where light leaks in is a part corresponding to _0- x coordinate on the X-axis, and y1-y coordinate on the Y-axis.

When data on the coordinates of the optical sensor calculated by the microcomputer 17 and the luminance difference in each coordinate are transmitted to the projector 20, the microcomputer 28 in the projector 20 converts the coordinates into suitable coordinates corresponding to the projector. And converts the image signal to the luminance based on the transmitted luminance difference.

Hereinafter, with reference to the graph shown on the right side of FIG. 5, a method for converting the coordinates calculated on the screen 10 into suitable coordinates corresponding to the projector 20 will be described. For example, when the resolution of the LCD projector is 1024 x 768, the coordinates on the screen shown in the left graph of FIG. 5 are converted into appropriate coordinates corresponding to the projector through Equation 2 below.

,

Thus, the y ₁ coordinate on the screen shown in the left graph of FIG. 5 is converted to the coordinate A = (y ₁ / y) 768 of the projector in the microcomputer 28. In this way, the coordinates of the graph shown on the left side of FIG. 5 are converted one-to-one to the coordinates of the graph shown on the right side of FIG. 5. That is, the coordinates on the screen are converted to the pixel coordinates of the LCD panel at the microcomputer 28. Based on the coordinates of the graph shown on the right side of FIG. 5, the microcomputer 28 outputs the original video signal until the line A in the Y-axis direction (22) and the line A to 24 (the luminance is compensated). Output the video signal.

Next, a method of generating an image signal whose luminance is compensated based on the transmitted luminance difference will be described.

First, as described above, when the full white pattern is projected from the projector onto the screen, the photosensors 16 mounted in the screen measure the luminance at the corresponding position. If the luminance of the original image region 12 projected on the screen is 500 ansi lumens and the luminance of the region 14 through which light has penetrated from the outside is 600 ansi lumens, the external luminance is set to 500 ansi as the reference luminance level. In the region 14 where light penetrates, the brightness should be reduced to 100 ansi, ie 20%. Therefore, when the luminance of the three input image signals R, G, and B is R ', G', and B ', respectively, the microcomputer 28 in the projector 20 is 0.8R', 0.8G ', and 0.8, respectively. A video signal having a compensated luminance of B 'is output. In this case, 0.8 becomes a luminance compensation coefficient, and the luminance compensation coefficient may be calculated through Equation 3 below.

Here, the reference luminance level is the lowest luminance level among the luminance levels output from the photosensors.

By adjusting the luminance of the image signal projected on the screen in the above manner, an image having uniform brightness can be displayed on the screen.

FIG. 6 is a graph illustrating a method of adjusting luminance of an image signal when light penetrates from the outside in the upper right side of the screen 10 according to another exemplary embodiment of the present invention. When the coordinates of the graph shown on the left side of FIG. 6 and the luminance difference data at each coordinate are transmitted to the projector 20, the microcomputer 28 in the projector 20 performs appropriate coordinate transformation, and the area where the luminance difference occurs ( Outputs a video signal whose luminance is compensated for.

In more detail, the coordinates on the screen shown in the graph shown on the left side of FIG. 6 are first converted by the microcomputer 28 into coordinates suitable for the projector as shown in the graph shown on the right side of FIG. Accordingly, x ₁ and y ₁ coordinates on the screen shown on the left side of FIG. 6 are converted into coordinates of B = (x ₁ / x) 1024 and C = (y ₁ / y) 768 in the micom 28, respectively. The microcomputer 28 outputs the original video signal up to B pixels before the first horizontal line, and outputs the video signal whose luminance is compensated from the B pixels. This operation is repeated up to C horizontal lines. After the C horizontal line, the original video signal is output to all the pixels on the line.

In this way, by outputting the video signal whose luminance is adjusted to the region where the luminance difference occurs, an image having uniform brightness can be displayed on the screen.

FIG. 7 is a graph for explaining a method of adjusting the brightness of an image signal when light penetrates from the outside with a predetermined slope in an upper right portion of the screen 10 according to another exemplary embodiment of the present invention. Doing. As shown in FIG. 7, the light penetrating area from the outside is not rectangular, and the boundary line has a constant slope. When coordinate data on the screen 10 as shown in the left graph of FIG. 7 is transmitted to the projector 20, the microcomputer 20 in the projector 20 performs appropriate coordinate transformation by Equation 2, and the luminance difference is The luminance-compensated video signal is output to the generated area 22.

In more detail, in the left graph of FIG. 7, x ₂ , x ₃ , y ₂ , and y ₃ coordinates are (x ₂ / x) 1024, (x ₃ / x) 1024, (y ₂ / y) 768 and (y ₃ / y) 768 coordinates respectively. Next, the microcomputer 28 outputs an original video signal up to (x ₂ / x) 1024 pixels before the first horizontal line, and outputs an image signal whose luminance is compensated from (x ₂ / x) 1024 pixels. In addition, the microcomputer 28 is originally (x ₂ / x) 1024 + {(x ₃ / x) 1024-(x ₂ / x) 1024} / (y ₂ / y) 768 pixels in the second horizontal line Outputs a video signal of (x ₂ / x) 1024 + {(x ₃ / x) 1024-(x ₂ / x) 1024} / (y ₂ / y) 768 pixels do. A similar approach is then repeated for the horizontal line. In each horizontal line, the original image signal is output before the lower pixel, and the luminance-compensated image signal is output thereafter.

First line: (x ₂ / x) 1024 pixels

Second line: (x ₂ / x) 1024 + {(x ₃ / x) 1024-(x ₂ / x) 1024} / (y ₂ / y) 768 pixels

Third line: (x ₂ / x) 1024 + 2 {(x ₃ / x) 1024- (x ₂ / x) 1024} / (y ₂ / y) 768 pixels

Fourth line: (x ₂ / x) 1024 + 3 {(x ₃ / x) 1024- (x ₂ / x) 1024} / (y ₂ / y) 768 pixels

:

(Y ₂ / y) 768 lines: (x ₃ / x) 1024 pixels

(Y ₂ / y) 768 + 1 line: (x ₃ / x) 1024+ {1024- (x ₃ / x) 1024} / {(y ₃ / y) 768- (y ₂ / y) 768} pixels

(Y ₂ / y) 768 + 2 lines: (x ₃ / x) 1024 + 2 {1024- (x ₃ / x) 1024} / {(y ₃ / y) 768- (y ₂ / y) 768} pixel

(Y ₂ / y) 768 + 2 lines: (x ₃ / x) 1024 + 3 {1024- (x ₃ / x) 1024} / {(y ₃ / y) 768- (y ₂ / y) 768} pixel

:

(Y ₃ / y) 768 lines: 1024 pixels

(Y ₃ / y) 768 lines to 768 lines: original video signal output to all pixels

By adjusting the luminance of the image signal projected on the screen in the above manner, an image with uniform brightness is displayed.

Now, the operation of the LCD projection system of the present invention having the above configuration will be described in more detail. 8 is a flowchart illustrating a compensation algorithm of an image signal in a preferred embodiment of the LCD projection system according to the present invention.

Referring to FIG. 8, when the projector 20 projects a full white pattern on the screen 10 (step 10), a plurality of optical sensors mounted in the screen detect the brightness of the light and display the screen. Transfer to the microcomputer 17 (step 12). The microcomputer 17 calculates coordinates of the optical sensors and calculates a luminance difference by comparing the luminance levels transmitted from the optical sensors (step 14). Next, the data on the coordinates and the luminance difference are transmitted to the projector through the transmitter in the screen (step 16). The data is received by the receiver in the projector and transmitted to the microcomputer 28 in the projector. The microcomputer 28 converts the received coordinates on the screen into suitable coordinates corresponding to the projector, sets a compensation interval that requires luminance compensation by generating a luminance difference (step 18), and then adjusts the luminance coefficient in the compensation interval. Calculation (step 20). Next, the microcomputer 28 determines whether the coordinate of the position where the image signal is to be output corresponds to the compensation section (step 22). If the coordinates correspond to the compensation section (YES in step 22), the microcomputer 28 compensates the input image signal using the luminance compensation coefficient and outputs the corresponding video signal to the corresponding coordinates of the screen. If the coordinates do not correspond to the compensation section (NO in step 22), the image signal having the original luminance is output as it is to the corresponding coordinates on the screen (step 26). Quit.

According to the present invention, when light penetrates a part of the screen of the LCD projection system by an external factor, the image projected on the screen is displayed with uniform brightness by compensating the brightness of the part. As a result, deterioration in image quality characteristics of the projector can be prevented, and eye fatigue of a viewer sensitive to light can be reduced.

In addition, according to the present invention, even when the area where the external light penetrates into the screen is not a rectangular shape, by recognizing the penetrating area very closely and outputting an image signal with luminance compensation, the image having uniform brightness To be displayed.

In the above, the present invention has been described with reference to the preferred embodiment. Those skilled in the art will appreciate that the present invention may be modified without departing from the spirit and scope of the invention. In other words, the present invention may be modified within the scope of the appended claims and should not be considered as being limited to the above-described exemplary embodiments.

Claims (6)

A projection type image display system having an automatic brightness adjustment function, which is composed of a screen and a projection type image display device, The screen is A plurality of optical sensors measuring luminance levels of light projected on the screen; A first micom that calculates coordinates on the screen for the optical sensors and compares luminance levels transmitted from the optical sensors to calculate luminance differences generated at each coordinate; A transmission unit for transmitting data about coordinates of the respective optical sensors transmitted from the first microcomputer and luminance difference in each coordinate to the projection image display device, The projection image display device A receiving unit for receiving data about coordinates transmitted from the transmitting unit of the screen and the luminance difference in each coordinate; A second microcomputer that compensates for the luminance of an image signal to be output at a position where the luminance difference occurs based on the coordinates transmitted from the receiving unit and the data on the luminance difference in each coordinate Projection type image display system having an automatic brightness adjustment function, characterized in that it comprises a. The method of claim 1, And the first micom calculates the luminance difference using the lowest luminance level among the luminance levels transmitted from the plurality of optical sensors as a reference level. The method of claim 1, And the second micom converts data about coordinates transmitted from the transmission unit of the screen into pixel coordinate data corresponding to the image display device. A method for automatically adjusting the brightness of a projection image display system comprising a screen and a projection image display device, (a) measuring a brightness level of an image projected at each point on the screen using a plurality of optical sensors mounted on the screen; (b) calculating coordinates on the screen for the photosensors and comparing the brightness levels measured by the photosensors to calculate a luminance difference occurring at each coordinate; (c) transmitting the calculated coordinates and data relating to the luminance difference at each coordinate to the projection image display device; (d) receiving, by the video display device, data relating to the coordinates and the luminance difference at each coordinate from the screen; (e) compensating for the luminance of the image signal to be output at the position where the luminance difference occurs based on the received coordinates and data relating to the luminance difference in each coordinate; Automatic brightness adjustment method of the projection image display device characterized in that it comprises a. The method of claim 4, wherein In step (a), Projecting a full white pattern on the screen; Measuring a luminance level of an image projected at each point on the screen by using a plurality of optical sensors mounted on the screen; Automatic brightness adjustment method of the projection type image display system, characterized in that consisting of. The method of claim 4, wherein The step (e) may include converting data about the coordinates transmitted from the screen into pixel coordinates corresponding to the video display device; Setting a luminance compensation coefficient at a coordinate at which a luminance difference occurs based on the converted pixel coordinates and the data on the luminance difference; Adjusting the luminance of an image signal at a corresponding pixel coordinate by using the luminance compensation coefficient Automatic brightness adjustment method of the projection type image display system, characterized in that consisting of.