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Apparatus of shielding VLF electric field emitted from front face of CRT in video allliance

A front panel, ultra-low frequency technology, applied in cathode ray tubes/electron beam tubes, image reproducers using cathode camera tubes, televisions, etc., can solve problems such as inability to completely offset the electric field noise of CRT71, increased cost of CRT71, and failure to pass

Inactive Publication Date: 2003-12-31
LG ELECTRONICS INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, such a way of shielding electromagnetic waves has caused an increase in the cost of manufacturing the CRT71
Moreover, the commonly used circuit cannot completely offset the electric field noise generated in the CRT71, and thus cannot pass the standard required by the Swedish Confedration of Professionals Employees

Method used

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  • Apparatus of shielding VLF electric field emitted from front face of CRT in video allliance
  • Apparatus of shielding VLF electric field emitted from front face of CRT in video allliance
  • Apparatus of shielding VLF electric field emitted from front face of CRT in video allliance

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Embodiment Construction

[0021] figure 2 is a schematic circuit diagram showing an apparatus according to the present invention for shielding VLF electric fields emanating from the front of a CRT in a video display.

[0022] see figure 2 , The VLF electric field shielding device includes: a flyback transformer 2, which is used to generate a high voltage according to the input level driving pulse signal, so as to provide the high voltage to the anode of the CRT1, and the flyback transformer 2 has an induction coil wound on the iron core with a predetermined number of turns Coil (not shown), in order to induce negative polarity pulse signal; Signal detection part 3, it is connected to the smoothing capacitor C that is connected on one end of flyback transformer 2 HV On one end, it is used to detect the anode voltage V supplied to the anode of CRT1 A ; The reverse amplification part 4 is used to reversely amplify the anode voltage V detected by the signal detection part 3 A The waveform shaping part 5...

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Abstract

An apparatus of shielding a very low frequency (VLF) electric field on the front face of a cathode ray tube (CRT) in a video appliance. The apparatus includes a signal detection section, an inversion-amplifying section, a waveform-shaping section, a signal synthesizing section, an output amplifying section, and an open-loop antenna. The VLF electric field generated from the CRT is offset by the electric field caused by the synthesized negative polarity pulse radiated through the open-loop antenna.

Description

technical field [0001] The present invention relates to a device for shielding a very low frequency (VLF) electric field in front of a cathode ray tube (CRT) in a video display. Background technique [0002] A video display, such as a monitor using a CRT, generally uses an electron gun to radiate electron beams to display images on a CRT screen. To properly position the beam on the screen, a magnetic field generated by a deflection yoke mounted on the neck of the CRT (not shown) is used. If current flows to the deflection yoke to generate the magnetic field, an electric field is also generated by the deflection yoke. Thus, a considerable amount of electromagnetic waves is always generated around the monitor. Therefore, devices for canceling this electromagnetic wave have been provided in common video displays. [0003] A circuit for eliminating electromagnetic waves in the above-mentioned conventional video display is shown in FIG. 1 . [0004] Referring to Fig. 1, the c...

Claims

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Application Information

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IPC IPC(8): H04N9/29H04N3/185H04N3/20
CPCH04N3/20H04N3/185H01J2229/0015H04N9/29
Inventor 宋熙永
Owner LG ELECTRONICS INC