Drive circuit for capacitive electroluminescent panels
First Claim
1. In a device having a capacitive electroluminescent lamp, a battery and signal generating means for providing first signals and second signals, the improvement comprising:
- a converter electrically connected to said battery, to said signal generating means, and to said capacitive electroluminescent lamp for producing current pulses, andswitching means electrically connected to said signal generating means, to said capacitive electroluminescent lamp, and to said converter and responsive to said second signals for switching a predetermined number of said current pulses to said capacitive electroluminescent lamp to produce light, and responsive to said first signals for reversing the polarity of said capacitive electroluminescent at the end of said predetermined number of current pulses whereby the combined effects of dc battery voltage and said current pulses which pulse charge the capacitance of said electroluminescent lamp combine to enhance the light output from said capacitive electroluminescent lamp.
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Accused Products
Abstract
A drive circuit is disclosed which includes a converter that provides current pulses that charge a capacitive electroluminescent lamp to produce light and a switching circuit that switches a predetermined number of successive current pulses at high frequency for progressively charging the electroluminescent lamp. The switching circuit also reverses the polarity of the electroluminescent lamp at low frequency when the electroluminescent lamp discharges at the end of a predetermined number of successive current pulses and before the electroluminescent lamp charges again by current pulses produced by the converter. The switching circuit is connected to and is responsive to signals provided by the timepiece frequency divider circuit and the converter is connected to the timepiece battery for stepping up the battery voltage to provide for the charging current pulses. The EL lamp is used as its own storage capacitor and receives substantially all of the energy provided by the converter.
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Citations
19 Claims
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1. In a device having a capacitive electroluminescent lamp, a battery and signal generating means for providing first signals and second signals, the improvement comprising:
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a converter electrically connected to said battery, to said signal generating means, and to said capacitive electroluminescent lamp for producing current pulses, and switching means electrically connected to said signal generating means, to said capacitive electroluminescent lamp, and to said converter and responsive to said second signals for switching a predetermined number of said current pulses to said capacitive electroluminescent lamp to produce light, and responsive to said first signals for reversing the polarity of said capacitive electroluminescent at the end of said predetermined number of current pulses whereby the combined effects of dc battery voltage and said current pulses which pulse charge the capacitance of said electroluminescent lamp combine to enhance the light output from said capacitive electroluminescent lamp. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An efficient drive circuit electrically connected to a capacitive electroluminescent lamp that provides backlighting for a timepiece in which the timepiece includes a battery and a frequency divider circuit, comprising:
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a converter electrically connected to said battery, to said frequency divider circuit, and to said capacitive electroluminescent lamp for stepping up the battery voltage to provide current pulses that charge said capacitive electroluminescent lamp to produce light, and switching means electrically connected to said frequency divider circuit, to said capacitive electroluminescent lamp, and to said converter and responsive to intermediate frequency signals provided by said frequency divider circuit for switching a predetermined number of successive current pulses at high frequency that progressively charge said capacitive electroluminescent lamp and for reversing the polarity of said capacitive electroluminescent lamp at low frequency when said capacitive electroluminescent lamp discharges at the end of a predetermined number of successive current pulses whereby the combined effects of dc battery voltage and said current pulses which pulse charge the capacitance of said electroluminescent lamp combine to enhance the light output from said capacitive electroluminescent lamp.
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Specification