• 한국정밀공학회지
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• 제19권11호
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• pp.89-95
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• 2002

A shadow mask inside the Braun tube of a TV is sustained by springs attached to the glass panel, its vibration cause the picture image to discolor, which is called the microphonic phenomenon. It is found that it results from resonance when the natural frequency of the shadow mask coincides with that of built-in speaker sound. This paper describes experimental and analytical investigations by using FEM on the vibration problem of the shadow mask assembly. The simulation scheme may be efficiently used to develop a new design for a large-screen flat TV.

• 소음진동
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• 제6권4호
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• pp.493-497
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• 1996

TVs or computer monitors with speakers often have a phenomenon called microphonic which shows fringe-like dark pattern on their screens. The major source of this phenomenon is vibration of the shadow mask inside of the Cathode RAY Tube(CRT) which is caused by the sound generated from the speakers. Reducing phenomenon microphonic by modifying the structure of the shadow mask frame in CRT has been examined in this study. A 15" for computer monitor were chosen. Using finite element analysis for vibration and impact, shape of the shadow mask frame was found to reduce microphonic phenomeon. Improved 15" monitors showed good results.d results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.135-140
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• 2013

This paper deals with noise reduction on a light source driving board in a projector. We analyze causes of noise/vibration in the circuit with the present increasing use of LD and LED driving boards. The main source of noise is the MLCC in the driving board. Our aim is to investigate how the mechanical arrangement of the circuit elements affects noise reduction. The result of our experiment shows that noise can be reduced by symmetrical arrangement and slots in PCB. This result is expected to facilitate a variety of applications for manufactures without a need to change circuit elements.

• 소음진동
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• 제5권1호
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• pp.123-132
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• 1995

The microphonic phenomenon in TV(television) is a phenomenon that a stained pattern locally appears in the screen or moves like waves. This can be observed when audio signal of TV has specific frequencies under loud volume of sound. In this study, microphonic phenomenon has been investigated, and two practical ways of circumventing this has been proposed. Based on modal analysis of several TV parts(Cathod Ray Tube, shadowmask, etc.), it was proved that the microphonic phenomenon is caused by the resonance of the shadow mask. One of the proposed ways to circumvent this phenonenon is increasing the thickness of the frame, the other is removing the middle welding points between the frame and the shadow mask. The effects of these modifications are evaluated by the finite element analysis, and the results show that the magnitude of vibration of shadow mask reduced by 10 - 20dB, which is large enough to provent microphonic phenomenon even under maximum level of sound volume.

• 한국정밀공학회지
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• 제12권3호
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• pp.144-152
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• 1995

TV microphonic phenomenon (black patterns overlapped on the image when TV sound is set too high) was studied experimentally. It was found that this phenomenon was due to the vibration generated at speakers, and transmitted to the CRT through the TV cabinet structure. Based on this fact, a simulative study was carried out on the assumption that the vibratory motion of the shadow mask located in the CRT could cause the landing error of electronic beam. The result of the simulation corresponded qualitatively with experi- mentally observed facts.

• 한국소음진동공학회논문집
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• 제23권6호
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• pp.495-501
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• 2013

This paper deals with noise reduction on a light source driving board in a projector. We analyze causes of noise/vibration in the circuit with the present increasing use of LD and LED driving boards. The main source of noise is the MLCC in the driving board. Our aim is to investigate how the mechanical arrangement of the circuit elements affects noise reduction. The result of our experiment shows that noise can be reduced by symmetrical arrangement and slots in PCB. This result is expected to facilitate a variety of applications for manufactures without a need to change circuit elements.