Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Patent
1999-06-11
2000-06-13
Wong, Don
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
315156, 381151, H04R 2500
Patent
active
060753242
ABSTRACT:
The invention provides a portable apparatus which eliminates noise generated by vibrations of an EL device without adhering a vibration preventing sheet to the apparatus. Microprocessor 3 of the portable apparatus displays characters and a graphic form on display unit 1, and in order to illuminate display unit 1, microprocessor 3 controls EL device driver 5 to generate an AC voltage and causes EL device 4 to emit light. EL device 4 vibrates itself with a frequency equal to the frequency of a driving voltage and generates noise. An output voltage signal having a voltage and a phase converted by reverse phase generator 6 is applied to receiver 7. Consequently, sound of a phase reverse to that of the generated noise is generated from receiver 7. The sound of the phase reverse to that of the noise generated from EL device 4 is combined in a space in front of the receiver with the noise generated from EL device, thereby cancelling the noise generated from EL device 4.
REFERENCES:
patent: 5649020 (1997-07-01), McClurg et al.
patent: 6005350 (1999-12-01), Hachiya et al.
Lee Wilson
NEC Corporation
Wong Don
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