Apparatus and method for dimming a gas discharge lamp
First Claim
1. A power supply for a gas discharge lamp, comprising:
- a converter that converts an input AC power signal to at least one DC signal;
an output transformer, having a primary winding and a secondary winding, the lamp being connected in circuit across said secondary winding;
a switching network that alternately provides first and second voltage signals across said primary winding, the first and second voltage signals comprising first and second drive pulses, such that there is a first dead time period between said first and second voltage signals, and there is a second dead time period between said second and first voltage signals, said network includinga first switch that switches the first voltage signal across said primary winding after the second dead time;
a second switch that switches the second voltage signal across said primary winding after the first dead time; and
a switch control circuit that controls the switching of said first and second switches to set the brightness level of said lamp by varying the length of at least one of the first and second dead time periods.
1 Assignment
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Accused Products
Abstract
A power supply for a gas discharge lamp includes a converter, a microprocessor switch control circuit, a driver, a switching network having two MOSFET switches, and an output transformer. A cross conduct inhibit circuit is connected in series between the driver and the switching network to prevent simultaneous operation of the switches. The power supply may further include a ground fault interrupt circuit and a ground continuity detector. A dimming module contains a potentiometer input device to vary the brightness of the lamp. The power supply operates at a preset level until the dimming module is connected. The dimming module cannot be removed without shutting off the power supply. The first and second MOSFETs switch first and second voltages across the transformer, thereby causing first and second drive pulses in the periodic output signal. Between the first and second and the second and first drive pulses are first and second dead times. The power supply sets the brightness level of the lamp by varying at least one of the dead time periods.
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Citations
113 Claims
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1. A power supply for a gas discharge lamp, comprising:
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a converter that converts an input AC power signal to at least one DC signal; an output transformer, having a primary winding and a secondary winding, the lamp being connected in circuit across said secondary winding; a switching network that alternately provides first and second voltage signals across said primary winding, the first and second voltage signals comprising first and second drive pulses, such that there is a first dead time period between said first and second voltage signals, and there is a second dead time period between said second and first voltage signals, said network including a first switch that switches the first voltage signal across said primary winding after the second dead time; a second switch that switches the second voltage signal across said primary winding after the first dead time; and a switch control circuit that controls the switching of said first and second switches to set the brightness level of said lamp by varying the length of at least one of the first and second dead time periods. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A method of changing the brightness level of a lamp, said lamp being connected between a first terminal and a second terminal, comprising:
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providing a first switch that is in circuit connection with a source of a first voltage; providing a second switch that is in circuit connection with a source of a second voltage; activating said first switch for a first period to thereby apply a first voltage signal across the first and second terminals, the first voltage signal comprising a first drive pulse; deactivating said first switch for a first dead time period; activating said second switch for a second period after said first dead time period has expired to thereby apply a second voltage signal across the first and second terminals, the second voltage signal comprising a second drive pulse; deactivating said second switch for a second dead time period; and varying at least one of said first dead time period and said second dead time period in response to a brightness control signal. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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56. A method of changing the brightness level of a lamp that is connected between a first terminal and a second terminal, comprising:
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providing a first switch that is in circuit connection with a source of a first voltage; providing a second switch that is in circuit connection with a source of a second voltage; activating said first switch for a first period to thereby apply a voltage signal of a first magnitude across said first and second terminals, the first voltage signal comprising a first drive pulse; deactivating said first switch for a substantially fixed first dead time period; activating said second switch for a second period to thereby apply a voltage signal of a second magnitude across said first and second terminals, the second voltage signal comprising a second drive pulse, after said first dead time period has expired; deactivating said second switch for a substantially fixed second dead time period; and varying the ratio of said first period and said second period in response to a brightness control signal. - View Dependent Claims (57)
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58. A ground fault interrupt circuit for a gas discharge lamp power supply, the power supply including an output transformer having a secondary winding having a center tap and connected in circuit across first and second terminals of the gas discharge lamp, said ground fault interrupt circuit comprising:
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an avalanche device connected in circuit to the center tap of the secondary winding; and a resistance device connected in circuit between the center tap of the secondary winding and a ground line. - View Dependent Claims (59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70)
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71. A ground continuity detector for a gas discharge lamp power supply that detects a discontinuity between a utility ground line of a power source and the power supply, said ground continuity detector comprising:
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a circuit ground line having a voltage that is substantially constant and substantially different in magnitude from the utility ground line; a chassis ground line connected in circuit to the utility ground line; and a ground continuity sensor connected in circuit between said circuit ground line and said chassis ground line, said ground continuity sensor being capable of generating a ground continuity fault signal when the voltage between said circuit ground line and said chassis ground line varies from a predetermined value. - View Dependent Claims (72, 73, 74, 75, 76, 77, 78, 79)
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80. A dimming module that may be used with a power supply for a gas discharge lamp, comprising:
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an input device, comprising a binary switch, that is used to set the brightness level of the gas discharge lamp and that includes a circuit that communicates to the power supply when the dimming module is connected to the power supply; and a connector that connects said dimming module in circuit to the power supply.
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81. A dimming module that may be used with a power supply for a gas discharge lamp, comprising:
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an input device that is used to set the brightness level of the gas discharge lamp and that includes a circuit that communicates to the power supply when the dimming module is connected to the power supply, said input device including a feedback circuit that generates a signal functionally related to the output of the gas discharge lamp; and a connector that connects said dimming module in circuit to the power supply.
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82. A dimming module that may be used with a power supply for a gas discharge lamp, comprising:
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an input device that is used to set the brightness level of the gas discharge lamp and that includes a circuit that communicates to the power supply when the dimming module is connected to the power supply; and a connector that connects said dimming module in circuit to the power supply; wherein said input device includes an RC filter connected in circuit to said connector.
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83. A power supply for a gas discharge lamp, comprising:
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a converter that converts an input AC power signal to at least one DC signal; an output transformer, having a primary winding and a secondary winding, the lamp being connected in circuit across said secondary winding; a switching network that alternately provides first and second drive pulse across said primary winding, such that there is a first dead time period between said first and second drive pulses, and there is a second dead time period between said second drive pulse and a first drive pulse of a next switching cycle;
said network includinga first switch that switches the first drive pulse across said primary winding after the second dead time; a second switch that switches the second drive pulse across said primary winding after the first dead time; and a switch control circuit that controls the switching of said first and second switches to change the brightness level of said lamp by varying the length of both of said first and second drive pulses while maintaining a fixed ratio other than 1 to 1 of said first drive pulse to said second drive pulse. - View Dependent Claims (85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96)
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84. A power supply for a gas discharge lamp, comprising:
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a converter that converts an input AC power signal to at least one DC signal; an output transformer, having a primary winding and a secondary winding, the lamp being connected in circuit across said secondary winding; a switching network that alternately provides first and second drive pulses across said primary winding, such that there is a first dead time period between said first and second drive pulses, and there is a second dead time period between said second drive pulse and the first drive pulse of the next switching cycle, said network including a first switch that switches the first drive pulse across said primary winding after the second dead time; a second switch that switches the second drive pulse across said primary winding after the first dead time; and a switch control circuit that controls the switching of said first and second switches to change the brightness level of said lamp from a first brightness level to a second brightness level by varying the length of one of the first and second dead time periods while maintaining the other of said dead time periods fixed.
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97. A method of changing the brightness level of a lamp, said lamp being connected between a first terminal and a second terminal, comprising:
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providing a first switch that is in circuit connection with a voltage source; providing a second switch that is in circuit connection with said voltage source; activating said first switch for a first period to thereby apply a first drive pulse across the first and second terminals; deactivating said first switch for a first dead time period; activating said second switch for a second period after said first dead time period to thereby apply a second drive pulse across the first and second terminals; deactivating said second switch for a second dead time period; and varying exactly one of said first dead time period and said second dead time period in response to a brightness control signal.
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98. A method of changing the brightness level of a lamp, said lamp being connected between a first terminal and a second terminal, comprising:
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providing a first switch that is in circuit connection with a voltage source; providing a second switch that is in circuit connection with said voltage source; activating said first switch for a first period to thereby apply a first drive pulse across the first and second terminals; deactivating said first switch for a first dead time period; activating said second switch for a second period after said first dead time period to thereby apply a second drive pulse across the first and second terminals; deactivating said second switch for a second dead time period; and varying both said first period and said second period in response to a brightness control signal while maintaining a fixed ratio between said first period and said second period, wherein said varying step includes varying exactly one of said first dead time period and said second dead time period in response to the brightness control signal. - View Dependent Claims (99, 100, 101, 102, 103)
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104. A dimming module used with a microprocessor-controlled power supply for a gas discharge lamp, comprising:
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an input device that is used to set the brightness level of the gas discharge lamp and that includes a circuit that communicates to the power supply when the dimming module is connected to the power supply, said input device providing an analog signal in response to which said microprocessor controls the brightness of said lamp; and a connector that connects said dimming module in circuit to the power supply. - View Dependent Claims (105, 106, 107, 108, 109, 110, 111, 112)
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113. A method of dimming a gas discharge lamp comprising the steps of:
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providing an input device that is used to vary the brightness level of a gas discharge lamp; providing a power supply that has set the gas discharge lamp to a predetermined brightness level; connecting the input device to the power supply; setting the input device to a selected level to generate a brightness signal and to vary the brightness of the lamp; and removing the input device and thereby shutting down the lamp.
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Specification