• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1155-1158
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• 2007

To reduce acoustic noise level of an AV projector, primary noise sources of AV projector were analyzed. Based on the analyzed result, methods to control each source are presented and tried. Structure-borne noise can be controlled by anti vibration design of mounting system, and air-borne noise by reducing flow resisitvity.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.205-210
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• 2005

A new configuration of LCD projectors for polarized stereoscopic projection having no light loss in the polarization process is suggested. In the proposed system, two polarizing filters that are employed in the conventional LCD polarized stereoscopic projection system causing additional light loss and image distortion are excluded by taking into account of polarization property of the LCD projector and image processing techniques. From some experimental results by using the Type-1 LCD projectors of NEC MT 1060R, light loss of the proposed system occurring in the polarization process is found to be zero and the resultant stereoscopic video image projected from this system is also found to be 213%, 75% and 300% brighter than those projected from the conventional Type-1 LCD projector-based, Type-2 LCD projector-based and Type-3 projector-based systems, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1427-1429
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• 2008

In this paper, an illumination system design using two lamps was proposed to improve the brightness of the projector. The proposal is based on the results from optical simulation. The prism array was applied to maintain the same optical properties, such as brightness distribution for the divergence angle and the composed beam size of the system. These were compared to those of the one UHP lamp system. The brightness of the two-lamp system, having a panel size of 0.74" and an f/2.9, increased by a factor of 1.7 when compared to the brightness of one UHP lamp system.

• Journal of Platform Technology
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• v.6 no.4
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• pp.3-10
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• 2018

A projection-based active information display system was proposed. The proposed system is based on Intelligent Space and a steerable projector mounted mobile robot which is called Ubiquitous Display (UD). In order to transfer visual information for a human in the Intelligent Space, the UD projects a certain shape of an image with a fixed size. Due to redundancy of degree of freedom (DOF), there are lots of situations to project a same shape and size of the image on a surface. In this paper, we describe a method to determine a goal posture of the UD. Here, the goal posture is the most efficient position and orientation of the UD so as to project visual information and it is determined by the Intelligent Space. To verify the proposed method, simulation and demonstration are carried out.

• Journal of Broadcast Engineering
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• v.13 no.6
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• pp.941-950
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• 2008

The quality of projector output image is influenced by the surrounding conditions such as the shape and color of screen, and environmental light. Therefore, techniques that ensure desirable image quality, regardless of such surrounding conditions, have been in demand and are being steadily developed. Among the techniques, radiometric compensation is a representative one. In general, radiometric compensation is achieved by measuring the color of the screen and environmental light based on an analysis of camera image of projector output image and then adjusting the color of projector input image in a pixel-wise manner. This process is not time-consuming for small sizes of images but the speed of the process drops linearly with respect to image size. In large sizes of images, therefore, reducing the time required for performing the process becomes a critical problem. Therefore, this paper proposes a fast radiometric compensation method. The method uses color filters for eliminating the color mixing between projector and camera because the speed of radiometric compensation depends mainly on measuring color mixing between projector and camera. By using color filters, there is no need to measure the color mixing. Through experiments, the proposed method improved the compensation speed by 44 percent while maintaining the projector output image quality. This method is expected to be a key technique for widespread use of projectors for large-scale and high-quality display.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.98-105
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• 2000

The projectors using liquid crystal display(LCD) have faults such as low optical efficiency, low brightness and even heat generation. To solve these problems reflective-type spatial light modulators based on MEMS (Microelectromechanical Systems) technology have emerged. Digital Micromirror DeviceTM(DMDTM), which was already developed by Texas Instruments Inc., and Thin-film Micromirror ArrayTM(TMATM), which has been recently developed by Daewoo Electronics Co., are the representative examples. The display using TMATM has particularly much higher optical efficiency than other projectors. But the micromirrors manufactured by semiconductor processes have inevitable distortion because of the limitations of the manufacturing processes, so that the distortions of their surfaces have great influence on the optical efficiency of the projector. This study investigated the effects of mirror flatness on the optical performance, including the optical efficiency, of the TMATM projector. That is to say, as a part of the efforts to enhance the performance of the TMATM projector, how much influence the form errors of a micromirror surface exert on the optical efficiency and the modulation of gray scale of the projector were analyzed through a pertinent modeling and simulations.

• Journal of the Korea Computer Graphics Society
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• v.17 no.4
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• pp.31-40
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• 2011

Projector-based visual systems are widely used for VR and experience display applications. But the illumination irregularity on the screen surface due to the screen material and its light reflection properties sometimes deteriorates the user experience. This phenomenon is particularly troublesome when the participants of the head tracking VR system such as CAVE or the motion generation experience system continually move around the system. One of reason to illumination irregularity is projector-screen specular reflection component to participant's eye's position and it's analysis needs high computation complexity. Similar to calculate specular lighting term using GPU's programmable shader, Our research adjusts every pixel's brightness in runtime with given 3D screen space model to reduce illumination irregularity. For doing that, Angle-based brightness compensate function are considered for specific screen installation and modified it for GPU-friendly compute and access. Two aspects are implemented, One is function access transformation from angular form to product and the other is piecewise linear interpolate approximation.

• Journal of KIISE:Software and Applications
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• v.37 no.1
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• pp.29-38
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• 2010

We propose an interactive projection technique to display details of a large image in a high resolution and brightness by tracking a portable projector. A closed-loop based tracking method is presented to update the projected image while a user changes the position of the detail area by moving the portable projector. A marker is embedded in the large image to indicate the position to be occupied by the detail image projected by the portable projector. The marker is extracted in sequential images acquired by a camera attached to the portable projector. The marker position in the large display image is updated under a constraint that the center positions of marker and camera frame coincide in every camera frame. The image and projective transformation for warping are calculated using the marker position and shape in the camera frame. The marker's four corner points are determined by a four-step segmentation process which consists of camera image preprocessing based on HSI, edge extraction by Hough transformation, quadrangle test, and cross-ratio test. The interactive projection system implemented by the proposed method performs at about 24fps. In the user study, the overall feedback about the system usability was very high.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1607-1610
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• 2005

A new configuration of LCD projectors for polarized stereoscopic projection having no light loss in the polarization process is suggested. In the proposed system, two polarizing filters that are employed in the conventional LCD polarized stereoscopic projection system causing additional light loss and image distortion are excluded by taking into account of polarization property of the LCD projector and image processing techniques. From some experimental results by using the Type-1 LCD projectors, light loss of the proposed system occurring in the polarization process is found to be zero.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.137-147
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• 2007

Projection-based augmented reality (AR) system refers to the system that accurately project high quality virtual information at the user-specified area by using the projector. Most of projection-based AR systems use the display device to support high quality and wide screen for increasing the user-immersion. Furthermore, they are implemented on the desktop environment due to the computational complexity. However, these projection-based AR systems are not suited as a mobile system and thus it may be inconvenient in the user point of view. Fortunately, Miniaturization of projectors and improved capacity of the mobile processor allowed the mobile AR system to be convenient. The limitation of established mobile AR system is that it uses small display screen which does not support high-resolutions and thus it may reduce the user-immersion into the system. In this paper, we propose portable projection-based display system, which overcomes the limitations of both projection-based and mobile-based AR systems. We have conducted the user evaluation to verify the effectiveness and the utmost capacity of the system.