EP0411617A2 - Method of lighting discharge lamp and discharge lamp lighting apparatus - Google Patents
Method of lighting discharge lamp and discharge lamp lighting apparatus Download PDFInfo
- Publication number
- EP0411617A2 EP0411617A2 EP90114791A EP90114791A EP0411617A2 EP 0411617 A2 EP0411617 A2 EP 0411617A2 EP 90114791 A EP90114791 A EP 90114791A EP 90114791 A EP90114791 A EP 90114791A EP 0411617 A2 EP0411617 A2 EP 0411617A2
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- EP
- European Patent Office
- Prior art keywords
- discharge lamp
- discharge
- circuit
- lighting
- starting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
- H05B41/382—Controlling the intensity of light during the transitional start-up phase
- H05B41/388—Controlling the intensity of light during the transitional start-up phase for a transition from glow to arc
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/02—Details
- H05B41/04—Starting switches
- H05B41/042—Starting switches using semiconductor devices
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
- H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
- H05B41/288—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps without preheating electrodes, e.g. for high-intensity discharge lamps, high-pressure mercury or sodium lamps or low-pressure sodium lamps
- H05B41/2881—Load circuits; Control thereof
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
- H05B41/382—Controlling the intensity of light during the transitional start-up phase
Definitions
- the present invention relates to a method of lighting a discharge lamp and a lighting apparatus for the discharge lamp and, more particularly, to a method of lighting a discharge lamp and a lighting apparatus for the discharge lamp, in which a timing at which an output from a lighting circuit is supplied to the discharge lamp after the discharge of the discharge lamp is started is controlled.
- a lighting circuit is formed by connecting an inverter having four transistors as switching elements to a power source, and a discharge lamp is connected to the output terminal of the lighting circuit through a choke coil and the secondary winding of a pulse transformer.
- the primary winding of the pulse transformer is connected to a starting circuit constituted by a thyristor, a constant-voltage conducting element, and a plurality of capacitors and resistors. A pulse voltage is to be applied from this starting circuit to the discharge lamp.
- the inverter when the power source is turned on, the inverter starts an oscillating operation. That is, the constant-voltage conducting element is ON/OFF-operated to ON/OFF-operate the thyristor. As a result, a high-voltage pulse is generated at the secondary winding of the pulse transformer and is applied across the discharge lamp. The discharge lamp is started by this high-voltage pulse, and is subsequently lighted by an output from the inverter. When the discharge lamp is lighted, since the voltage between the two ends of the discharge lamp drops, the operation of the starting circuit is stopped.
- the secondary winding of the pulse transformer is interposed between the output terminal of the lighting circuit and the discharge lamp as described above, however, since one end of the secondary winding is directly connected to the discharge lamp, and the other end is connected to the discharge lamp through the lighting circuit, a high-voltage pulse generated at the secondary winding is reduced by the lighting circuit. For this reason, the pulse voltage of a high-voltage pulse must be set to be undesirably high.
- a high-voltage pulse or a pulse current generated at the secondary winding may run around and enter the lighting circuit, and may damage switching elements such as transistors.
- the inductance may be reduced.
- a sufficient high-voltage pulse cannot be obtained at the start of a lighting operation. Hence, the lighting operation cannot be started.
- an object of the present invention to provide a method of lighting a discharge lamp and a lighting apparatus for the discharge lamp, in which a pulse voltage can be applied to the discharge lamp without loss, and a breakdown of switching elements of a lighting circuit can be prevented by preventing a high-voltage pulse or a pulse current from being supplied to the lighting circuit at the start of a lighting operation.
- a method of lighting a discharge lamp comprising the steps of supplying a starting high voltage, required for starting an initial discharge of the discharge lamp; maintaining the initial discharge by supplying power lower than a predetermined power required for main lighting; and supplying a predetermined power required for main lighting of the discharge lamp to the discharge lamp, while the initial discharge is maintained.
- a discharge lamp lighting apparatus comprising a discharge lamp; a lighting circuit, having an output terminal connected to said discharge lamp, for supplying a predetermined power to the discharge lamp to effect main lighting of the discharge lamp; and a starting circuit, connected to said discharge lamp in parallel with said lighting circuit, for starting initial discharge of the discharge lamp and maintaining the initial discharge with power lower than a predetermined power supplied from the lighting circuit to the discharge lamp, characterized by further comprising a control circuit for controlling a timing at which a predetermined power from the lighting circuit is supplied to the discharge lamp after the initial discharge is started by the starting circuit and while the initial discharge is maintained.
- a discharge lamp lighting apparatus is designed such that an inverter 102 for supplying a high-frequency output is connected to a first DC power source 12 so as to constitute a lighting circuit 100, and a discharge lamp, e.g., a high-voltage discharge lamp 18 is connected to the output terminal of the lighting circuit 100, i.e., the output terminal of the inverter 102, through a series circuit of a capacitor 14 and a choke coil 16.
- the inverter 102 includes two MOS transistors 106 and 108 having gates connected to a driver 104.
- Each of diodes 110 and 112 having polarities shown in Fig. 1 is connected between the source and the drain of a corresponding one of the MOS transistors 106 and 108.
- the drain of the transistor 108 is connected to the source of the transistor 106, and the DC power source 12 is connected between the drain of the transistor 106 and the source of the transistor 108.
- the driver 104 serves to alternately switch the transistors 106 and 108.
- the negative electrode of a DC power source 114 and the emitter of a transistor 116 having a collector connected to the positive electrode thereof are connected to the driver 104.
- the transistor 116 is used to control the driver 104.
- the driver 104 i.e., the inverter 102 (the lighting circuit 100) is ON/OFF-controlled by a voltage to be applied to the base of the transistor 116.
- a starting circuit 200 is connected to the discharge lamp 18.
- a secondary winding 2022 of a pulse transformer 202 as a high voltage generator is connected in parallel with the discharge lamp 18.
- the secondary winding 2022 of the pulse transformer and a series circuit of a resistor 204 and a capacitor 206 are connected in parallel.
- a primary winding 2021 of the pulse transformer 202 is connected in parallel with the capacitor 206 through a semiconductor switch 208.
- the series circuit of the resistor 204 and the capacitor 206 of the starting circuit 200 is connected to a second DC power source 66 through a series circuit of a resistor 62 and the collector and emitter of a transistor 64.
- a resistor 68 is connected between the base and collector of the transistor 64. As will be described later, a predetermined voltage is applied to the base of the transistor 64.
- one power source may be commonly used as the first and second power sources 12 and 66.
- An a1-a2 voltage is applied to the base-emitter path of the transistor 116 at a timing shown in Fig. 2A.
- a b1-b2 voltage is applied to the base-emitter path of the transistor 64 at a timing shown in Fig. 2B.
- the b1-b2 voltage is applied to the base-emitter path of the transistor 64 at time t0 shown in Figs. 2A and 2B so as to turn on the transistor 64.
- the starting circuit 200 is then connected to the second DC power source 66 through the resistor 62, and an operation of the circuit 200 is started.
- a pulse current periodically flows in the primary winding 2021 of the pulse transformer 202, and a high-voltage pulse is generated at the secondary winding 2022.
- This high-voltage pulse is applied across the discharge lamp 18 so that the discharge lamp 18 starts an initial glow discharge.
- initial glow discharge is maintained by the power supplied from the starting circuit 200.
- the power supplied in this case is lower than a predetermined value needed for main lighting.
- the a1-a2 voltage is applied to the base-emitter path of the transistor 116 of the lighting circuit 100 at time t1 so as to turn on the transistor 116.
- the driver 104 is started to alternately switch the transistors 106 and 108.
- a predetermined high-frequency power which is greater than the power supplied from the starting circuit 200 to the discharge lamp 18, is supplied from the inverter 102 to the discharge lamp 18 through the capacitor 14 and the choke coil 16.
- the state of the discharge lamp 18 is shifted from the initial glow discharge to a main arc discharge, and a normal lighting operation is performed.
- the transistor 64 is turned off at time t2, the operation of the starting circuit 200 is stopped.
- the starting circuit 200 is operated first to cause the initial glow discharge of the discharge lamp 18, and this glow discharge is maintained with a low power for a predetermined period of time.
- the lighting circuit is operated to shift the state of the discharge lamp 18 from the initial glow discharge to the main arc discharge.
- the lighting circuit 100 is operated after the discharge lamp 18 starts discharge and the impedance lowers.
- high voltage is applied to the transistors 106 and 108.
- a large switching loss can be prevented, and a switching operation of the transistors 106 and 108 can be performed within a safe operating region.
- the impedance of the discharge lamp 18 lowers, and therefore the pulse which is generated at the secondary winding 2022 of the pulse transformer 202 is reduced by the discharge lamp 18. For this reason, even if this high-voltage pulse runs around during an operation of, e.g., the lighting circuit 100, there is no possibility that the transistors 106 and 108 are damaged. In addition, the lighting circuit 100 is not operated before the discharge lamp 18 starts initial discharge. Thus, even if the high-voltage pulse is applied to the transistors 106 and 108, these transistors are not damaged.
- the secondary winding 2022 of the pulse transformer 202 serves as a high impedance with respect to a high-frequency output from the lighting circuit 100. For this reason, there is no possibility that power loss is caused by the secondary winding 2022, and hence a lighting operation of the discharge lamp 18 is performed by proper power.
- the operation timing of the lighting circuit 100 is controlled by the ON/OFF operation of the transistor 116.
- the same effects as described above can be obtained even if the operation timing of the lighting circuit 100 is controlled by the ON/OFF operation of the power source 12 itself.
- a choke coil 20 having a relatively large inductance is series-connected between a choke coil 16 and a discharge lamp 18.
- a normally-open contact 22m of a first relay 22 is connected in parallel with the choke coil 20.
- the normally-open contact 22m is ON/OFF-operated by a first relay driver 24 at a timing shown in Fig. 4A.
- a starting circuit 200 is connected to a second DC power source 66 through a series circuit of a normally-open contact 70m of a second relay 70 and a resistor 62.
- the second relay 70 is ON/OFF-operated by a second relay driver 72 at a timing shown in Fig. 4B.
- a lighting circuit 1001 is obtained by omitting the timing circuits for the lighting circuit, such as the power source 114 and the control transistor 116, from the lighting circuit 100 shown in Fig. 1.
- the second relay 70 when the second relay 70 is turned on by the second relay driver 72 at time t0, the normally-open contact 70m is closed.
- the starting circuit 200 is then operated, and the discharge lamp 18 is started/lighted by a high-voltage pulse from a secondary winging 2022 of a pulse transformer 202. As a result, the discharge lamp 18 starts an initial glow discharge. At this time, the power supplied from the starting circuit 200 is lower that the power needed for main lighting.
- the lighting circuit 1001 is also operated at this time.
- the two choke coils 16 and 20 are connected between the output terminal of the lighting circuit 1001 and the discharge lamp 18, the composite impedance of the coils 16 and 20 with respect to the high-frequency output from the lighting circuit 1001 is large. For this reason, high-frequency power supplied to the discharge lamp 18 is small. Therefore, at this time, the operation of the discharge lamp 18 is not shifted to an arc discharge.
- the normally-open contact 22m is closed.
- the choke coil 20 is short-circuited, and hence proper high-frequency power is supplied to the discharge lamp 18.
- the operation of the discharge lamp 18 is then shifted from an initial glow discharge to a main arc discharge, and a normal lighting operation is performed.
- the second relay is turned off to stop the starting circuit 200.
- the normally-open contact 22m of the relay 22 is opened before the discharge lamp 18 starts the initial discharge.
- the high-voltage pulse applied to the discharge lamp 18 is not applied directly to the transistors 106 and 108 in the lighting circuit 1001 which is being operated.
- the contact 22m of the relay 22 is closed after the discharge lamp 18 starts the initial discharge.
- the switching loss of the transistor can be reduced and the destruction of the transistor can be prevented.
- the timing circuits for the lighting circuit such as the power source 114 and the transistors 116 shown in Fig. 1 are omitted. However, these circuits may be arranged. With these circuits, the lighting circuit in the second embodiment can be operated at the same timing as in the first embodiment.
- the node of the cathode of a diode 261 and the anode of a diode 262 and the node of the cathode of a diode 263 and the anode of a diode 264 are respectively connected to the two ends of a choke coil 20.
- the diodes 261 to 264 constitute a diode bridge circuit 26.
- the collector and emitter of a transistor 28 are respectively connected to the node of the cathodes of the diodes 261 and 263 and the node of the anodes of the diodes 262 and 264.
- the base and emitter of the transistor 28 are respectively connected to the output terminals of an amplifier 30.
- the amplifier 30 is driven/controlled by a timer 34 connected to a third DC power source 32.
- the collector and emitter of a phototransistor 74a of a photocoupler 74 are respectively connected to the base and emitter of a transistor 64.
- a light-emitting diode 74b of the photocoupler 74 is connected to an output terminal of an amplifier 76.
- the amplifier 76 is driven/controlled by a timer 80 connected to a fourth DC power source 78.
- a c1-c2 voltage is applied from the amplifier 30 to the base-emitter path of the transistor 28 at a timing shown in Fig. 6A.
- a b1-b2 voltage is applied from the amplifier 76 to the base-emitter path of the transistor 64 through the photocoupler 74 at a timing shown in Fig. 6B.
- the amplifier 76 is driven first by the timer 80 at time t0.
- the transistor 64 is then turned on to drive a starting circuit 200.
- a high-voltage pulse is generated by a secondary winding 2022 of a pulse transformer 202, and the discharge lamp 18 is started to establish an initial glow discharge.
- the power supplied from the starting circuit 200 to the discharge lamp 18 is lower than the power needed for main lighting.
- a lighting circuit 1001 is operated.
- two choke coils 16 and 20 are series-connected between the output terminal of the lighting circuit 1001 and the discharge lamp 18 in series, the composite impedance of the coils 16 and 20 with respect to the high-frequency output from the lighting circuit 1001 is increased. Therefore, the high-frequency power to be supplied to the discharge lamp 18 is reduced, and the operation of the discharge lamp 18 is not shifted to an arc discharge at this time.
- the amplifier 30 is driven by the timer 34 at time t1 to turn on the transistor 28.
- the choke coil 20 is short-circuited through the diode bridge circuit 26.
- Proper high-frequency power is supplied from the lighting circuit 1001 to the discharge lamp 18, and the operation of the discharge lamp 18 is shifted from the initial glow discharge to a main arc discharge so as to be normally operated.
- the choke coil 20 is bypassed by the diode bridge circuit 26 and the lighting circuit 1001 is connected directly to the starting circuit 200.
- the switching loss of the transistor can be reduced and the destruction of the transistor can be prevented.
- the transistor 64 is turned off at time t2 by means of the timer 80. After the discharge lamp 18 is turned on, the starting circuit 200, the operation of which has become unnecessary, is turned off. Thus, power consumption is reduced.
- the starting circuit is constituted by the pulse transformer 202 having one primary winding and one secondary winding, the resistor 204, the capacitor 206, and the semiconductor switch 208.
- the present invention is not limited to this.
- Fig. 7 shows a modification of the starting circuit.
- a starting circuit 2001 includes a pulse transformer 210 as a high voltage generator having two primary windings 21011 and 21012 and one secondary winding 2102.
- One end of one primary winding 21011 of the pulse transformer 210 is connected to the node of a resistor 204 and a capacitor 206 which are connected in series.
- the other end of one primary winding 21011 is connected to the anode of a unidirectional three-terminal thyristor 212.
- One end of the other primary winding 21012 of the pulse transformer 210 is connected to the node of a resistor 214 and a capacitor 216 which constitute a series circuit together with a resistor 218.
- the other end of the primary winding 21012 is connected to one end of a semiconductor switch 208.
- the gate of the thyristor 212 is connected to the node of the capacitor 216 and the resistor 218.
- One end of each of the secondary winding 2102 and the resistors 204 and 214 is connected to one end of a discharge lamp 18.
- the other end of each of the capacitor 206, the resistor 218, and the semiconductor switch 208, and the cathode of the thyristor 212 are connected to the other end of the discharge lamp 18.
- a high-voltage pulse is also generated at the secondary winding 2102 of the pulse transformer 210 by using the starting circuit 2001 having the above-described arrangement. Therefore, the starting circuit 2001 provides the same function as that of the starting circuits 200 shown in Figs. 1, 3, and 5.
- Fig. 8 shows another modification of the starting circuit.
- a lighting circuit 1002 is designed such that an inverter 120 having four transistors 36, 38, 40, and 42 as switching elements is connected to a first DC power source 12.
- a discharge lamp 18 is connected to the output terminal of the lighting circuit 1002 through a choke coil 16.
- a secondary winding 2022 of a pulse transformer 202 is connected in parallel with the discharge lamp 18.
- a primary winding 2021 of the pulse transformer 202 is connected to the output terminal of a starting circuit 2002.
- a second DC power source 66 is connected to the input terminal of the starting circuit 2002 through a series circuit of a resistor 62 and a transistor 64.
- the discharge lamp 18 is connected in parallel with the input terminal of the starting circuit 2002.
- a capacitor 220 is connected in parallel with the second DC power source 66, and a capacitor 224 is connected in parallel with the capacitor 220 through a resistor 222.
- a constant-voltage conducting element 228 is connected in parallel with the capacitor 224 through a series circuit of the primary winding 2021 of the pulse transformer 202 and a capacitor 226. Note that diodes 44, 46, 48, and 50 for absorbing surges are connected in parallel with the transistors 36, 38, 40, and 42, respectively.
- the transistors 36 and 38 are ON/OFF-driven by a low-frequency wave, and the transistors 40 and 42 are ON/OFF-driven by high-frequency wave.
- a voltage is applied between terminals b1 and b2 to turn on the transistor 64, and the starting circuit 2002 is operated.
- a high-voltage pulse is generated from the secondary winding 2022 of the pulse transformer 202 and is applied to the discharge lamp 18.
- the discharge lamp 18 is then started to establish an initial glow discharge.
- a driver (not shown) of the inverter 120 is started.
- a switching operation of the transistors 36 and 38 is performed by a low-frequency wave
- a switching operation of the transistors 40 and 42 is performed by a high-frequency wave.
- a lighting wave obtained by superposing a high-frequency wave on a low-frequency wave is supplied from the inverter 120 to the discharge lamp 18, and the initial glow discharge of the discharge lamp 18 is shifted to a main arc discharge.
- Fig. 9 shows still another modification of the starting circuit.
- the diodes 44, 46, 48, and 50 which are respectively connected in parallel with the transistors 36, 38, 40, and 42 of the inverter 120 in Fig. 8 are omitted.
- An inverter 120′ is designed such that transistors 36, 38, 40, and 42 are ON/OFF-driven by a low-frequency wave. That is, the transistors 36 and 40 and the transistors 38 and 42 are alternately operated.
- Fig 10 shows the fourth embodiment of the present invention.
- a discharge lamp 18 is maintained in an initial DC arc discharge without establishing a glow discharge, and power required for main lighting of the discharge lamp 18 is subsequently supplied from a lighting circuit 100.
- a starting circuit 2003 is connected to the discharge lamp 18.
- the starting circuit 2003 includes first and second pulse transformers 230 and 232, a semiconductor switch 234, and a unidirectional three-terminal thyristor 236.
- the starting circuit 2003 further includes a first series circuit of a resistor 238, a capacitor 240, and a resistor 242, and a second series circuit of a resistor 244 and a capacitor 246.
- the discharge lamp 18 is connected to a second DC power source 66 through a series circuit of a transistor 64, a resistor 62, a secondary winding 2322 of the second pulse transformer, 232 and a secondary winding 2302 of the first pulse transformer 230.
- the above-described first and second series circuits are connected to the second DC power source 66 through a series circuit of the transistor 64 and the resistor 62.
- One end of a primary winding 2301 of the first pulse transformer is connected to the node of the resistor 238 and the capacitor 240 of the first series circuit.
- the other end of the primary winding 2301 is connected to the negative electrode of the second DC power source 66 through the semiconductor switch 234.
- One end of the primary winding 2321 of the second transformer 232 is connected to the node of the resistor 244 and the capacitor 246 of the second series circuit.
- the other end of the primary winding 2321 is connected to the negative electrode of the second DC power source 66 through the thyristor 236.
- a1-a2 voltage is applied to the base-emitter path of a control transistor 116 of the lighting circuit 100 at a timing shown in Fig. 11A.
- a b1-b2 voltage is applied to the base-emitter path of the transistor 64 at a timing shown in Fig. 11B.
- the b1-b2 voltage is applied first to the base-emitter path of the transistor 64 at time t0 so as to turn on the transistor 64.
- the starting circuit 2003 is connected to the second DC power source 66 through the resistor 62, and starts an operation.
- the capacitors 240 and 246 are charged, and the semiconductor switch 234 is turned on.
- the capacitor 240 is discharged through the primary winding 2301 of the first pulse transformer 230 and the semiconductor switch 234.
- a high-voltage pulse is generated at the secondary winding 2302 of the first pulse transformer 230 and is applied to the discharge lamp 18.
- the thyristor 236 is rendered conductive, and the capacitor 246 is discharged through the primary winding 2321 of the second pulse transformer 232 and the thyristor 236.
- a high-voltage pulse having energy large enough to start and maintain the initial discharge of the discharge lamp 18 is generated at the secondary winding 2322 of the second pulse transformer 232, and is supplied to the discharge lamp 18.
- the discharge lamp 18 is maintained in the initial DC arc discharge by the starting circuit 2003.
- the power supplied from the starting circuit 2003 to the discharge lamp 18 is lower than the predetermined power needed for main lighting.
- the a1-a2 voltage is applied to the base-emitter path of the transistor 116, and the transistor 116 is turned on.
- An operation of a driver 104 is started, and transistors 106 and 108 are alternately operated. With this operation, high-frequency power required to maintain the lighting operation is supplied from an inverter 102 to the discharge lamp 18 through a capacitor 14 and a choke coil 16.
- the transistor 64 is turned off at time t2 to stop the starting circuit 2003.
- the discharge lamp 18 is set in a lighting state after the arc discharge is directly maintained without a glow discharge.
- This system therefore, can prevent a lighting failure which is often caused when a glow discharge is shifted to an arc discharge.
- the lamp voltage of a discharge lamp is high during a glow discharge. Therefore, in order to connect the discharge lamp to a lighting circuit in a glow discharge state, the withstand voltage of a switching element of the lighting circuit must be set to be high. In this embodiment, however, since the discharge voltage is connected to the lighting circuit in an arc discharge state, the switching element of the lighting circuit need not have a high withstand voltage. In other words, a breakdown of the switching element of the lighting circuit can be further reliably prevented.
- the arrangement of the starting circuit is not limited to the one described in this embodiment.
- the starting circuit may have arrangements shown in Figs. 12 and 13.
- Fig. 12 shows a circuit arrangement of a modification of the starting circuit of the discharge lamp lighting apparatus in Fig. 10.
- a starting circuit 2004 includes a pulse transformer 248 as a high voltage generator constituted by a primary winding 2481 and a secondary winding 2482.
- one end of the primary winding 2481 of the pulse transformer 248 is connected to the node of a resistor 250 and a capacitor 252.
- the other end of the primary winding 2481 is connected to the other end of a discharge lamp 18 through a semiconductor switch 254.
- one end of the discharge lamp 18 is connected to the other end of the resistor 250 through the secondary winding 2482 of the pulse transformer 248.
- the other end of the discharge lamp 18 is connected to the other end of the capacitor 252.
- Fig. 13 shows a circuit arrangement of another modification of the starting circuit of the discharge lamp lighting apparatus shown in Fig. 10.
- a starting circuit 2005 includes a pulse transformer 254 as a high voltage generator constituted by two primary windings 25411 and 25412 and one secondary winding 2542.
- One end of one primary winding 25411 of the pulse transformer 254 is connected to the node of a resistor 256 and a semiconductor switch 258.
- the other end of the primary winding 25411 is connected to the other end of a discharge lamp 18 through a series circuit of a capacitor 260 and a resistor 262.
- one end of the other primary winding 25412 is connected to the node of a resistor 264 and a capacitor 266, and the other end thereof is connected to the other end of the discharge lamp 18 through a unidirectional three-terminal thyristor 268.
- one end of the discharge lamp 18 is connected to the other end of each of the resistors 256 and 264 through the secondary winding 2542 of the pulse transformer 254.
- the other end of the discharge lamp 18 is connected to the other end of each of the semiconductor switch 258 and the capacitor 266.
- the gate of the thyristor 268 is connected to the node of the capacitor 260 and the resistor 262.
- a circuit for directly causing an arc discharge of a discharge lamp can be applied to the lighting circuit shown in Fig. 3.
- Fig. 14 shows a circuit arrangement of the fifth embodiment of the present invention.
- a discharge lamp lighting apparatus is designed such that a boosting inverter 130 is a DC power source 12.
- the inverter 130 is constituted by a known circuit. More specifically, the inverter 130 is constituted by a pair of MOS transistors 106 and 108, a push-pull control circuit 132 for controlling a switching operation of the transistors 106 and 108, and an output transformer 134.
- a half-bridge circuit 146 constituting a lighting circuit 1004 is connected between the two ends of a series circuit of the capacitors 140 and 142 as the output terminals of the voltage doubler rectifier 144.
- the half-bridge circuit 146 includes a pair of known MOS transistors 148 and 150 which are connected in series, and a half-bridge drive controller 152 for controlling a switching operation of the transistors 148 and 150.
- the drain of the transistor 148 is connected to the positive terminal of the capacitor 140
- the source of the transistor 150 is connected to the negative terminal of the capacitor 142.
- a discharge lamp 18 is connected between the node of the source of the transistor 148 and the drain of the transistor 150, and the node of the capacitors 140 and 142 through a series circuit of a first energization detector 154, a normally-closed contact 156m of a third relay 156, and a current limiting choke 158.
- a starting circuit 2006 is connected to the discharge lamp 18 through a second energization detector 160.
- the starting circuit 2006 is connected to the capacitor 140 through a normally-open contact 162m of a fourth relay 162 so as to obtain an operating power source from the capacitor 140.
- a capacitor incorporated in the starting circuit 2006 is charged in accordance with a predetermined time constant. When the charge level of the capacitor reaches a predetermined level, the capacitor is discharged, and a current including a pulse is generated by a pulse transformer as a high-voltage generator. This operation is intermittently repeated.
- a relay switching circuit 164 is connected to the DC power source 12.
- the relay switching circuit 164 has an arrangement shown in Fig. 15. More specifically, a series voltage divider constituted by resistors 302 and 304, a series circuit of an npn transistor 306 and the fourth relay 162, and a series circuit of an npn transistor 308 and the third relay 156 are connected to the DC power source 12. Note that diodes 310 and 312 for absorbing surges are connected in parallel with the relays 156 and 162, respectively.
- the noninverting input terminal (+) of a comparator 314 is connected to the node of the resistors 302 and 304.
- a resistor 316 is connected between the output terminal and the noninverting input terminal (+) of the comparator 314.
- the inverting input terminal (-) of the comparator 314 is connected to the positive electrode of the power source 12 through a series circuit of a diode 318, a resistor 320, and a phototransistor 322T of a photocoupler 322, which constitute the second energization detector 160.
- a light-emitting diode 322D of the photocoupler 322 is inserted in the energization path between the starting circuit 2006 and the discharge lamp 18.
- the first energization detector 154 includes a current transformer 324.
- a primary winding 3241 of the transformer 324 is inserted in the energization path between the half-bridge circuit 146 and the discharge lamp 18.
- a resistor 326 is connected between the two ends of a secondary winding 3242 of the current transformer 324.
- the two ends of the secondary winding 3242 are respectively connected to one end of a capacitor 334 through diodes 328 and 330 and a resistor 332.
- an intermediate tap of the secondary winding 3242 is connected to the other end of the capacitor 334 and to the negative electrode of the DC power source 12.
- the node of the capacitor 334 and the resistor 332 is connected to the inverting input terminal (-) of the comparator 314 through a diode 336.
- a series circuit of resistors 338 and 340 and a series circuit of a diode 342 and a capacitor 344 are connected between the output terminal of the comparator 314 and the negative electrode of the DC power source 12.
- the capacitor 334 constitutes a delay circuit together with a series circuit of resistors 346 and 348, which is connected in parallel therewith.
- the base of the transistor 308 is connected to the node of the resistors 338 and 340.
- the base of the transistor 306 is connected to the node of the resistors 346 and 348 through a Zener diode 350.
- the starting circuit 2006 is connected to the power source 12, and starts an operation.
- the starting circuit 2006 when charging of the capacitor is started, and the charge level reaches a predetermined level a predetermined period of time T1 (time t13) after time t12, a pulse shown in Fig. 16E is generated and supplied to the discharge lamp 18.
- T1 time t13
- a pulse shown in Fig. 16E is generated and supplied to the discharge lamp 18.
- a discharge current flows upon reception of the pulse.
- the power supplied from the starting circuit 2006 is lower than the power needed for main lighting.
- the light-emitting diode 322D of the photocoupler 322 is operated, and the phototransistor 322T is turned on.
- a high-level voltage is applied to the inverting input terminal (-) of the comparator 314 through the diode 318.
- the input level of the inverting input terminal (-) then becomes higher than that of the noninverting input terminal (+), and the output level of the comparator 314 goes to low level.
- the transistor 308 is immediately turned off at time t13, and the third relay 156 is turned off with a slight delay at time t14.
- the normally-closed contact 156m of the relay 156 is turned on.
- a power required for main discharge starts to be supplied from the half-bridge circuit 146 to the discharge lamp 18.
- a voltage is generated at the secondary winding 3242 of the current transformer 324, and application of a high-level voltage to the inverting input terminal (-) of the comparator 314 is started also through the diode 336.
- the capacitor 344 When an output from the comparator 314 is set at low level, the capacitor 344 is discharged through the resistors 346 and 348. The transistor 306 is then turned off after a lapse of a time T2 ( ⁇ T1) (at time t15) before the next pulse is generated by the starting circuit 2006 as shown in Fig. 16C, and the fourth relay 162 is turned off with a slight delay at time t16 as shown in Fig. 16D.
- the starting circuit 2006 is disconnected from the power source 12, and the current supplying operation to the discharge lamp 18 is stopped.
- a current is supplied only from the half-bridge 146, and the lighting state of the discharge lamp 18 is maintained.
- a lamp discharge current shown in Fig. 16I flows in the discharge lamp 18 after the operation is started.
- Figs. 17A through 17I are timing charts for explaining such a case.
- the DC power source 12 is turned off at time t21 and is subsequently turned on again at time t22 as shown in Fig. 17A.
- the transistors 306 and 308 are turned on.
- the fourth and third relays 162 and 156 are then operated at time t23.
- the normally-open contact 162m of the fourth relay 162 is closed, and the normally-closed contact 156m of the third relay 156 is opened.
- the transistor 306 is turned off with a delay of a predetermined period of time T4, i.e., at time t27.
- the fourth relay 162 is turned off (at time t28), as shown in Fig. 17D.
- the current supplying operation from the starting circuit 2006 to the discharge lamp 18 is stopped.
- the transistor 306 is turned on at time t30 to operate the fourth relay 162, and the normally-open contact 162m is closed to immediately operate the starting circuit 2006. Meanwhile, the transistor 308 is turned on to operate the third relay 156, and the normally-closed contact 156m is opened to immediately disconnect the half-bridge circuit 146 from the discharge lamp 18.
- the starting circuit 2006 is immediately operated, and the half-bridge circuit 146 is immediately disconnected from the discharge lamp 18, thus controlling starting/lighting of the discharge lamp 18.
- the starting circuit 2006 When the starting circuit 2006 is operated to supply a current including a pulse to the discharge lamp 18, since the half-bridge 146 equivalent to the lighting circuit 1004 is disconnected from the discharge lamp 18, there is no possibility that the pulse enters the half-bridge circuit 146 and damages semiconductor elements in the circuit 146, e.g., the MOS transistors 106 and 108.
- the half-bridge circuit 146 is connected to the discharge lamp 18 so as to start supply of a current from the half-bridge circuit 146 to the discharge lamp 18. Thereafter, the operation of the starting circuit 2006 is stopped by disconnecting the circuit 2006 from the power source before the next pulse is generated by the circuit 2006. Therefore, the power supplying operations from the starting circuit 2006 and the half-bridge circuit 146 overlap, and the lighting operation of the discharge lamp 18 can be stably maintained. Furthermore, even if the current supplying operations overlap, since no pulse is generated by the starting circuit 2006 during this period, there is no possibility that a pulse runs around and enters the half-bridge circuit 146.
- the energization detectors are constituted by a photocoupler, a current transformer, and the like.
- the present invention is not limited to this.
- supply of a current from the starting circuit to the discharge lamp is stopped by disconnecting the starting circuit from the power source.
- this operation may be performed by disconnecting the starting circuit from the discharge lamp.
- the lighting circuit is constituted by the half-bridge circuit.
- the present invention is not limited to this.
Abstract
A discharge lamp (18) is connected to the output terminal of a lighting circuit (100). A starting circuit (200) is connected in parallel with the discharge lamp (18). A driver (104) and a transistor (116) in the lighting circuit (100), and a transistor (64) on the starting circuit (200) side serve to control a timing at which an output from the lighting circuit (100) is supplied to the discharge lamp (18). When a power source (12) is tuned on, a glow discharge of the discharge lamp (18) is maintained by the transistor (64) using power supplied from a pulse transformer (202) of the starting circuit (200). Subsequently, the glow discharge is shifted to an arc discharge by power supply from the lighting circuit (100) in accordance with a predetermined timing control operation by means of the driver (104) and the transistor (116), thereby lighting the discharge lamp (18).
Description
- The present invention relates to a method of lighting a discharge lamp and a lighting apparatus for the discharge lamp and, more particularly, to a method of lighting a discharge lamp and a lighting apparatus for the discharge lamp, in which a timing at which an output from a lighting circuit is supplied to the discharge lamp after the discharge of the discharge lamp is started is controlled.
- As a conventional discharge lamp lighting apparatus, an apparatus disclosed in, e.g., Published Unexamined Japanese Patent Application No. 63-150892 is known. In this discharge lamp lighting apparatus, a lighting circuit is formed by connecting an inverter having four transistors as switching elements to a power source, and a discharge lamp is connected to the output terminal of the lighting circuit through a choke coil and the secondary winding of a pulse transformer. In addition the primary winding of the pulse transformer is connected to a starting circuit constituted by a thyristor, a constant-voltage conducting element, and a plurality of capacitors and resistors. A pulse voltage is to be applied from this starting circuit to the discharge lamp.
- In the discharge lamp lighting apparatus having such an arrangement, when the power source is turned on, the inverter starts an oscillating operation. That is, the constant-voltage conducting element is ON/OFF-operated to ON/OFF-operate the thyristor. As a result, a high-voltage pulse is generated at the secondary winding of the pulse transformer and is applied across the discharge lamp. The discharge lamp is started by this high-voltage pulse, and is subsequently lighted by an output from the inverter. When the discharge lamp is lighted, since the voltage between the two ends of the discharge lamp drops, the operation of the starting circuit is stopped.
- In the apparatus in which the secondary winding of the pulse transformer is interposed between the output terminal of the lighting circuit and the discharge lamp as described above, however, since one end of the secondary winding is directly connected to the discharge lamp, and the other end is connected to the discharge lamp through the lighting circuit, a high-voltage pulse generated at the secondary winding is reduced by the lighting circuit. For this reason, the pulse voltage of a high-voltage pulse must be set to be undesirably high.
- In addition, a high-voltage pulse or a pulse current generated at the secondary winding may run around and enter the lighting circuit, and may damage switching elements such as transistors.
- Moreover, when the discharge lamp is to be lighted by a high-frequency wave or a lighting wave on which a high-frequency wave is superposed, since the inductance of the secondary winding is greatly increased, proper power cannot be supplied to the discharge lamp. In order to solve this problem, the inductance may be reduced. However, if the inductance is reduced, a sufficient high-voltage pulse cannot be obtained at the start of a lighting operation. Hence, the lighting operation cannot be started.
- It is, therefore, an object of the present invention to provide a method of lighting a discharge lamp and a lighting apparatus for the discharge lamp, in which a pulse voltage can be applied to the discharge lamp without loss, and a breakdown of switching elements of a lighting circuit can be prevented by preventing a high-voltage pulse or a pulse current from being supplied to the lighting circuit at the start of a lighting operation.
- According to a first aspect of the present invention, there is provided a method of lighting a discharge lamp comprising the steps of supplying a starting high voltage, required for starting an initial discharge of the discharge lamp; maintaining the initial discharge by supplying power lower than a predetermined power required for main lighting; and supplying a predetermined power required for main lighting of the discharge lamp to the discharge lamp, while the initial discharge is maintained.
- According to a second aspect of the invention, there is provided a discharge lamp lighting apparatus comprising a discharge lamp; a lighting circuit, having an output terminal connected to said discharge lamp, for supplying a predetermined power to the discharge lamp to effect main lighting of the discharge lamp; and a starting circuit, connected to said discharge lamp in parallel with said lighting circuit, for starting initial discharge of the discharge lamp and maintaining the initial discharge with power lower than a predetermined power supplied from the lighting circuit to the discharge lamp,
characterized by further comprising a control circuit for controlling a timing at which a predetermined power from the lighting circuit is supplied to the discharge lamp after the initial discharge is started by the starting circuit and while the initial discharge is maintained. - This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
- Fig. 1 is a circuit diagram showing an arrangement of a discharge lamp lighting apparatus according to an embodiment of the present invention;
- Figs. 2A and 2B are timing charts showing an operation timing of the discharge lamp lighting apparatus in Fig. 1;
- Fig. 3 is a circuit diagram showing an arrangement of a discharge lamp lighting apparatus according to the second embodiment of the present invention;
- Figs. 4A and 4B are timing charts showing an operation timing of a relay of the discharge lamp lighting apparatus in Fig. 3;
- Fig. 5 is a circuit diagram showing an arrangement of a discharge lamp lighting apparatus according to the third embodiment of the present invention;
- Figs. 6A and 6B are timing charts showing an operation timing of the discharge lamp lighting apparatus in Fig. 5;
- Fig. 7 is a circuit diagram showing an arrangement of a starting circuit, as a modification, in the discharge lamp lighting apparatuses in Figs. 1, 3, and 5;
- Fig. 8 is a circuit diagram showing an arrangement of another modification of the starting circuit in the discharge lamp lighting apparatuses in Figs. 1, 3, and 5;
- Fig. 9 is a circuit diagram showing an arrangement of still another modification of the starting circuit in the discharge lamp lighting apparatuses in Figs. 1, 3, and 5;
- Fig. 10 is a circuit diagram showing an arrangement of a discharge lamp lighting apparatus according to the fourth embodiment of the present invention;
- Figs. 11A and 11B are timing charts showing an operation timing of the discharge lamp lighting apparatus in Fig. 10;
- Fig. 12 is a circuit diagram showing an arrangement of a starting circuit, as a modification, in the discharge lamp lighting apparatus in Fig. 10;
- Fig. 13 is a circuit diagram showing an arrangement of another modification of the starting circuit in the discharge lamp lighting apparatus in Fig. 10;
- Fig. 14 is a circuit diagram showing an arrangement of a discharge lamp lighting apparatus according to the fifth embodiment of the present invention;
- Fig. 15 is a circuit diagram showing a detailed arrangement of a relay switching circuit in Fig. 14;
- Figs. 16A to 16I are timing charts showing an operation timing of each component of the discharge lamp lighting apparatus in Fig. 14 in a normal lighting operation; and
- Figs. 17A to 17I are timing charts showing an operation timing of each component of the discharge lamp lighting apparatus in Fig. 14 in a lighting operation including failures to cause the discharge lamp to discharge and to keep a discharge.
- Embodiments of the present invention will be described below with reference to the accompanying drawings.
- As shown in Fig. 1, a discharge lamp lighting apparatus according to the present invention is designed such that an
inverter 102 for supplying a high-frequency output is connected to a firstDC power source 12 so as to constitute alighting circuit 100, and a discharge lamp, e.g., a high-voltage discharge lamp 18 is connected to the output terminal of thelighting circuit 100, i.e., the output terminal of theinverter 102, through a series circuit of acapacitor 14 and achoke coil 16. - The
inverter 102 includes twoMOS transistors driver 104. Each ofdiodes MOS transistors transistor 108 is connected to the source of thetransistor 106, and theDC power source 12 is connected between the drain of thetransistor 106 and the source of thetransistor 108. Note that thedriver 104 serves to alternately switch thetransistors - In addition, the negative electrode of a
DC power source 114 and the emitter of atransistor 116 having a collector connected to the positive electrode thereof are connected to thedriver 104. Thetransistor 116 is used to control thedriver 104. As will be described later, thedriver 104, i.e., the inverter 102 (the lighting circuit 100), is ON/OFF-controlled by a voltage to be applied to the base of thetransistor 116. - In addition to the
lighting circuit 100, astarting circuit 200 is connected to thedischarge lamp 18. In thestarting circuit 200, asecondary winding 202₂ of apulse transformer 202 as a high voltage generator is connected in parallel with thedischarge lamp 18. Thesecondary winding 202₂ of the pulse transformer and a series circuit of aresistor 204 and acapacitor 206 are connected in parallel. Furthermore, aprimary winding 202₁ of thepulse transformer 202 is connected in parallel with thecapacitor 206 through asemiconductor switch 208. - The series circuit of the
resistor 204 and thecapacitor 206 of thestarting circuit 200 is connected to a secondDC power source 66 through a series circuit of aresistor 62 and the collector and emitter of atransistor 64. In addition, aresistor 68 is connected between the base and collector of thetransistor 64. As will be described later, a predetermined voltage is applied to the base of thetransistor 64. - Note that one power source may be commonly used as the first and
second power sources - An a₁-a₂ voltage is applied to the base-emitter path of the
transistor 116 at a timing shown in Fig. 2A. A b₁-b₂ voltage is applied to the base-emitter path of thetransistor 64 at a timing shown in Fig. 2B. - An operation of the discharge lamp lighting apparatus having the above described arrangement will be described below. The b₁-b₂ voltage is applied to the base-emitter path of the
transistor 64 at time t₀ shown in Figs. 2A and 2B so as to turn on thetransistor 64. The startingcircuit 200 is then connected to the secondDC power source 66 through theresistor 62, and an operation of thecircuit 200 is started. When the startingcircuit 200 is operated, a pulse current periodically flows in the primary winding 202₁ of thepulse transformer 202, and a high-voltage pulse is generated at the secondary winding 202₂. This high-voltage pulse is applied across thedischarge lamp 18 so that thedischarge lamp 18 starts an initial glow discharge. Then, initial glow discharge is maintained by the power supplied from the startingcircuit 200. The power supplied in this case is lower than a predetermined value needed for main lighting. - Subsequently, the a₁-a₂ voltage is applied to the base-emitter path of the
transistor 116 of thelighting circuit 100 at time t₁ so as to turn on thetransistor 116. As a result, thedriver 104 is started to alternately switch thetransistors circuit 200 to thedischarge lamp 18, is supplied from theinverter 102 to thedischarge lamp 18 through thecapacitor 14 and thechoke coil 16. - Thus, the state of the
discharge lamp 18 is shifted from the initial glow discharge to a main arc discharge, and a normal lighting operation is performed. When thetransistor 64 is turned off at time t₂, the operation of the startingcircuit 200 is stopped. - In this manner, the starting
circuit 200 is operated first to cause the initial glow discharge of thedischarge lamp 18, and this glow discharge is maintained with a low power for a predetermined period of time. Subsequently, the lighting circuit is operated to shift the state of thedischarge lamp 18 from the initial glow discharge to the main arc discharge. Specifically, thelighting circuit 100 is operated after thedischarge lamp 18 starts discharge and the impedance lowers. Thus, high voltage is applied to thetransistors transistors - In particular, when the initial discharge is maintained, the impedance of the
discharge lamp 18 lowers, and therefore the pulse which is generated at the secondary winding 202₂ of thepulse transformer 202 is reduced by thedischarge lamp 18. For this reason, even if this high-voltage pulse runs around during an operation of, e.g., thelighting circuit 100, there is no possibility that thetransistors lighting circuit 100 is not operated before thedischarge lamp 18 starts initial discharge. Thus, even if the high-voltage pulse is applied to thetransistors - Note that the secondary winding 202₂ of the
pulse transformer 202 serves as a high impedance with respect to a high-frequency output from thelighting circuit 100. For this reason, there is no possibility that power loss is caused by the secondary winding 202₂, and hence a lighting operation of thedischarge lamp 18 is performed by proper power. - Furthermore, in this embodiment, the operation timing of the
lighting circuit 100 is controlled by the ON/OFF operation of thetransistor 116. However, the same effects as described above can be obtained even if the operation timing of thelighting circuit 100 is controlled by the ON/OFF operation of thepower source 12 itself. - The second embodiment of the present invention will be described below with reference to Fig. 3 and Figs. 4A and 4B. Note that the same reference numerals in the second embodiment denote the same parts as in the first embodiment, and a detailed description thereof will be omitted.
- Referring to Fig. 3, a
choke coil 20 having a relatively large inductance is series-connected between achoke coil 16 and adischarge lamp 18. A normally-open contact 22m of afirst relay 22 is connected in parallel with thechoke coil 20. The normally-open contact 22m is ON/OFF-operated by afirst relay driver 24 at a timing shown in Fig. 4A. - A starting
circuit 200 is connected to a secondDC power source 66 through a series circuit of a normally-open contact 70m of asecond relay 70 and aresistor 62. Thesecond relay 70 is ON/OFF-operated by asecond relay driver 72 at a timing shown in Fig. 4B. - Note that a
lighting circuit 100₁ is obtained by omitting the timing circuits for the lighting circuit, such as thepower source 114 and thecontrol transistor 116, from thelighting circuit 100 shown in Fig. 1. - In the second embodiment, when the
second relay 70 is turned on by thesecond relay driver 72 at time t₀, the normally-open contact 70m is closed. The startingcircuit 200 is then operated, and thedischarge lamp 18 is started/lighted by a high-voltage pulse from asecondary winging 202₂ of apulse transformer 202. As a result, thedischarge lamp 18 starts an initial glow discharge. At this time, the power supplied from the startingcircuit 200 is lower that the power needed for main lighting. - The
lighting circuit 100₁ is also operated at this time. However, since the twochoke coils lighting circuit 100₁ and thedischarge lamp 18, the composite impedance of thecoils lighting circuit 100₁ is large. For this reason, high-frequency power supplied to thedischarge lamp 18 is small. Therefore, at this time, the operation of thedischarge lamp 18 is not shifted to an arc discharge. - When the
first relay 22 is operated by thefirst relay driver 24 at time t₁, the normally-open contact 22m is closed. As a result, thechoke coil 20 is short-circuited, and hence proper high-frequency power is supplied to thedischarge lamp 18. The operation of thedischarge lamp 18 is then shifted from an initial glow discharge to a main arc discharge, and a normal lighting operation is performed. At time t₂, the second relay is turned off to stop the startingcircuit 200. - As described above, in the second embodiment, the normally-
open contact 22m of therelay 22 is opened before thedischarge lamp 18 starts the initial discharge. Thus, the high-voltage pulse applied to thedischarge lamp 18 is not applied directly to thetransistors lighting circuit 100₁ which is being operated. Thecontact 22m of therelay 22 is closed after thedischarge lamp 18 starts the initial discharge. Thus, in the second embodiment, like the above-described first embodiment, the switching loss of the transistor can be reduced and the destruction of the transistor can be prevented. - In this embodiment, therefore, the same effects as in the first embodiment can be obtained.
- In the second embodiment, the timing circuits for the lighting circuit, such as the
power source 114 and thetransistors 116 shown in Fig. 1 are omitted. However, these circuits may be arranged. With these circuits, the lighting circuit in the second embodiment can be operated at the same timing as in the first embodiment. - The third embodiment of the present invention will be described below with reference to Fig. 5 and Figs. 6A and 6B. Note that the same reference numerals in the third embodiment denote the same parts as in the above-described embodiments, and a detailed description thereof will be omitted.
- Referring to Fig. 5, the node of the cathode of a diode 26₁ and the anode of a
diode 26₂ and the node of the cathode of a diode 26₃ and the anode of adiode 26₄ are respectively connected to the two ends of achoke coil 20. The diodes 26₁ to 26₄ constitute adiode bridge circuit 26. The collector and emitter of atransistor 28 are respectively connected to the node of the cathodes of the diodes 26₁ and 26₃ and the node of the anodes of thediodes transistor 28 are respectively connected to the output terminals of anamplifier 30. Theamplifier 30 is driven/controlled by atimer 34 connected to a thirdDC power source 32. - The collector and emitter of a
phototransistor 74a of a photocoupler 74 are respectively connected to the base and emitter of atransistor 64. A light-emittingdiode 74b of the photocoupler 74 is connected to an output terminal of anamplifier 76. Theamplifier 76 is driven/controlled by atimer 80 connected to a fourthDC power source 78. - A c₁-c₂ voltage is applied from the
amplifier 30 to the base-emitter path of thetransistor 28 at a timing shown in Fig. 6A. A b₁-b₂ voltage is applied from theamplifier 76 to the base-emitter path of thetransistor 64 through the photocoupler 74 at a timing shown in Fig. 6B. - In the third embodiment, the
amplifier 76 is driven first by thetimer 80 at time t₀. Thetransistor 64 is then turned on to drive a startingcircuit 200. As a result, a high-voltage pulse is generated by a secondary winding 202₂ of apulse transformer 202, and thedischarge lamp 18 is started to establish an initial glow discharge. At this time, the power supplied from the startingcircuit 200 to thedischarge lamp 18 is lower than the power needed for main lighting. In addition, alighting circuit 100₁ is operated. However, since twochoke coils lighting circuit 100₁ and thedischarge lamp 18 in series, the composite impedance of thecoils lighting circuit 100₁ is increased. Therefore, the high-frequency power to be supplied to thedischarge lamp 18 is reduced, and the operation of thedischarge lamp 18 is not shifted to an arc discharge at this time. - Subsequently, the
amplifier 30 is driven by thetimer 34 at time t₁ to turn on thetransistor 28. With this operation, thechoke coil 20 is short-circuited through thediode bridge circuit 26. Proper high-frequency power is supplied from thelighting circuit 100₁ to thedischarge lamp 18, and the operation of thedischarge lamp 18 is shifted from the initial glow discharge to a main arc discharge so as to be normally operated. - In the third embodiment, too, after the
discharge lamp 18 starts the initial discharge, thechoke coil 20 is bypassed by thediode bridge circuit 26 and thelighting circuit 100₁ is connected directly to the startingcircuit 200. Thus, in the third embodiment, like the first and second embodiments, the switching loss of the transistor can be reduced and the destruction of the transistor can be prevented. - In the third embodiment, the
transistor 64 is turned off at time t₂ by means of thetimer 80. After thedischarge lamp 18 is turned on, the startingcircuit 200, the operation of which has become unnecessary, is turned off. Thus, power consumption is reduced. - In the embodiments shown in Figs. 1, 3, and 5, the starting circuit is constituted by the
pulse transformer 202 having one primary winding and one secondary winding, theresistor 204, thecapacitor 206, and thesemiconductor switch 208. However, the present invention is not limited to this. - Fig. 7 shows a modification of the starting circuit.
- Referring to Fig. 7, a starting circuit 200₁ includes a
pulse transformer 210 as a high voltage generator having twoprimary windings 210₁₁ and 210₁₂ and one secondary winding 210₂. One end of one primary winding 210₁₁ of thepulse transformer 210 is connected to the node of aresistor 204 and acapacitor 206 which are connected in series. The other end of one primary winding 210₁₁ is connected to the anode of a unidirectional three-terminal thyristor 212. One end of the other primary winding 210₁₂ of thepulse transformer 210 is connected to the node of aresistor 214 and acapacitor 216 which constitute a series circuit together with aresistor 218. The other end of the primary winding 210₁₂ is connected to one end of asemiconductor switch 208. - The gate of the
thyristor 212 is connected to the node of thecapacitor 216 and theresistor 218. One end of each of the secondary winding 210₂ and theresistors discharge lamp 18. The other end of each of thecapacitor 206, theresistor 218, and thesemiconductor switch 208, and the cathode of thethyristor 212 are connected to the other end of thedischarge lamp 18. - A high-voltage pulse is also generated at the secondary winding 210₂ of the
pulse transformer 210 by using the starting circuit 200₁ having the above-described arrangement. Therefore, the starting circuit 200₁ provides the same function as that of the startingcircuits 200 shown in Figs. 1, 3, and 5. - Fig. 8 shows another modification of the starting circuit.
- Referring to Fig. 8, a
lighting circuit 100₂ is designed such that aninverter 120 having fourtransistors DC power source 12. Adischarge lamp 18 is connected to the output terminal of thelighting circuit 100₂ through achoke coil 16. A secondary winding 202₂ of apulse transformer 202 is connected in parallel with thedischarge lamp 18. A primary winding 202₁ of thepulse transformer 202 is connected to the output terminal of astarting circuit 200₂. A secondDC power source 66 is connected to the input terminal of thestarting circuit 200₂ through a series circuit of aresistor 62 and atransistor 64. In addition, thedischarge lamp 18 is connected in parallel with the input terminal of thestarting circuit 200₂. - In the
starting circuit 200₂, acapacitor 220 is connected in parallel with the secondDC power source 66, and acapacitor 224 is connected in parallel with thecapacitor 220 through aresistor 222. A constant-voltage conducting element 228 is connected in parallel with thecapacitor 224 through a series circuit of the primary winding 202₁ of thepulse transformer 202 and acapacitor 226. Note thatdiodes transistors - In the
inverter 120, thetransistors transistors - In this modification, a voltage is applied between terminals b₁ and b₂ to turn on the
transistor 64, and thestarting circuit 200₂ is operated. As a result, a high-voltage pulse is generated from the secondary winding 202₂ of thepulse transformer 202 and is applied to thedischarge lamp 18. Thedischarge lamp 18 is then started to establish an initial glow discharge. After this initial glow discharge is maintained for a certain period of time, a driver (not shown) of theinverter 120 is started. As a result, a switching operation of thetransistors transistors inverter 120 to thedischarge lamp 18, and the initial glow discharge of thedischarge lamp 18 is shifted to a main arc discharge. - In this modification, therefore, the same effects as in the above-described embodiments can be obtained.
- Furthermore, in this modification, since the lighting wave obtained by superposing the high-frequency wave on the low-frequency wave is supplied from the
inverter 120 to thedischarge lamp 18 during a normal lighting operation, acoustic resonance can be prevented, and the load characteristics of the lighting circuit can be improved. - Fig. 9 shows still another modification of the starting circuit.
- In the circuit shown in Fig. 9, the
diodes transistors inverter 120 in Fig. 8 are omitted. Aninverter 120′ is designed such thattransistors transistors transistors - Even in the apparatus wherein the
inverter 120′ is driven by a low-frequency wave in this manner, a glow discharge of adischarge lamp 18 is maintained by astarting circuit 200₂ during an initial operation, and the glow discharge of thedischarge lamp 18 can be shifted to an arc discharge by subsequently operating alighting circuit 100₃. Therefore, in this embodiment the same effects as in the above-described embodiments can be obtained. - Fig 10 shows the fourth embodiment of the present invention. In this embodiment, a
discharge lamp 18 is maintained in an initial DC arc discharge without establishing a glow discharge, and power required for main lighting of thedischarge lamp 18 is subsequently supplied from alighting circuit 100. - More specifically, a
starting circuit 200₃ is connected to thedischarge lamp 18. Thestarting circuit 200₃ includes first andsecond pulse transformers semiconductor switch 234, and a unidirectional three-terminal thyristor 236. Thestarting circuit 200₃ further includes a first series circuit of aresistor 238, acapacitor 240, and aresistor 242, and a second series circuit of a resistor 244 and acapacitor 246. Thedischarge lamp 18 is connected to a secondDC power source 66 through a series circuit of atransistor 64, aresistor 62, a secondary winding 232₂ of the second pulse transformer, 232 and a secondary winding 230₂ of thefirst pulse transformer 230. - The above-described first and second series circuits are connected to the second
DC power source 66 through a series circuit of thetransistor 64 and theresistor 62. One end of a primary winding 230₁ of the first pulse transformer is connected to the node of theresistor 238 and thecapacitor 240 of the first series circuit. The other end of the primary winding 230₁ is connected to the negative electrode of the secondDC power source 66 through thesemiconductor switch 234. One end of the primary winding 232₁ of thesecond transformer 232 is connected to the node of the resistor 244 and thecapacitor 246 of the second series circuit. The other end of the primary winding 232₁ is connected to the negative electrode of the secondDC power source 66 through thethyristor 236. - An a₁-a₂ voltage is applied to the base-emitter path of a
control transistor 116 of thelighting circuit 100 at a timing shown in Fig. 11A. Similarly, a b₁-b₂ voltage is applied to the base-emitter path of thetransistor 64 at a timing shown in Fig. 11B. - In this embodiment, the b₁-b₂ voltage is applied first to the base-emitter path of the
transistor 64 at time t₀ so as to turn on thetransistor 64. As a result, thestarting circuit 200₃ is connected to the secondDC power source 66 through theresistor 62, and starts an operation. - In the
starting circuit 200₃, thecapacitors semiconductor switch 234 is turned on. After thesemiconductor switch 234 is turned on, thecapacitor 240 is discharged through the primary winding 230₁ of thefirst pulse transformer 230 and thesemiconductor switch 234. As a result, a high-voltage pulse is generated at the secondary winding 230₂ of thefirst pulse transformer 230 and is applied to thedischarge lamp 18. Subsequently, thethyristor 236 is rendered conductive, and thecapacitor 246 is discharged through the primary winding 232₁ of thesecond pulse transformer 232 and thethyristor 236. With this operation, a high-voltage pulse having energy large enough to start and maintain the initial discharge of thedischarge lamp 18 is generated at the secondary winding 232₂ of thesecond pulse transformer 232, and is supplied to thedischarge lamp 18. In this manner, thedischarge lamp 18 is maintained in the initial DC arc discharge by thestarting circuit 200₃. At this time, the power supplied from thestarting circuit 200₃ to thedischarge lamp 18 is lower than the predetermined power needed for main lighting. - At time t₁, the a₁-a₂ voltage is applied to the base-emitter path of the
transistor 116, and thetransistor 116 is turned on. An operation of adriver 104 is started, andtransistors inverter 102 to thedischarge lamp 18 through acapacitor 14 and achoke coil 16. - Subsequently, the
transistor 64 is turned off at time t₂ to stop thestarting circuit 200₃. - In this manner, the
discharge lamp 18 is set in a lighting state after the arc discharge is directly maintained without a glow discharge. - This system, therefore, can prevent a lighting failure which is often caused when a glow discharge is shifted to an arc discharge. The lamp voltage of a discharge lamp is high during a glow discharge. Therefore, in order to connect the discharge lamp to a lighting circuit in a glow discharge state, the withstand voltage of a switching element of the lighting circuit must be set to be high. In this embodiment, however, since the discharge voltage is connected to the lighting circuit in an arc discharge state, the switching element of the lighting circuit need not have a high withstand voltage. In other words, a breakdown of the switching element of the lighting circuit can be further reliably prevented.
- Note that the arrangement of the starting circuit is not limited to the one described in this embodiment. For example, the starting circuit may have arrangements shown in Figs. 12 and 13.
- Fig. 12 shows a circuit arrangement of a modification of the starting circuit of the discharge lamp lighting apparatus in Fig. 10. Referring to Fig. 12, a
starting circuit 200₄ includes apulse transformer 248 as a high voltage generator constituted by a primary winding 248₁ and a secondary winding 248₂. In thestarting circuit 200₄, one end of the primary winding 248₁ of thepulse transformer 248 is connected to the node of aresistor 250 and acapacitor 252. The other end of the primary winding 248₁ is connected to the other end of adischarge lamp 18 through asemiconductor switch 254. In addition, one end of thedischarge lamp 18 is connected to the other end of theresistor 250 through the secondary winding 248₂ of thepulse transformer 248. The other end of thedischarge lamp 18 is connected to the other end of thecapacitor 252. - Fig. 13 shows a circuit arrangement of another modification of the starting circuit of the discharge lamp lighting apparatus shown in Fig. 10. Referring to Fig. 13, a
starting circuit 200₅ includes apulse transformer 254 as a high voltage generator constituted by twoprimary windings 254₁₁ and 254₁₂ and one secondary winding 254₂. One end of one primary winding 254₁₁ of thepulse transformer 254 is connected to the node of aresistor 256 and asemiconductor switch 258. The other end of the primary winding 254₁₁ is connected to the other end of adischarge lamp 18 through a series circuit of acapacitor 260 and aresistor 262. In thestarting circuit 200₅, one end of the other primary winding 254₁₂ is connected to the node of aresistor 264 and acapacitor 266, and the other end thereof is connected to the other end of thedischarge lamp 18 through a unidirectional three-terminal thyristor 268. In addition, one end of thedischarge lamp 18 is connected to the other end of each of theresistors pulse transformer 254. The other end of thedischarge lamp 18 is connected to the other end of each of thesemiconductor switch 258 and thecapacitor 266. In addition, the gate of thethyristor 268 is connected to the node of thecapacitor 260 and theresistor 262. - If the starting circuit shown in Fig. 10, 12, or 13 is used, a circuit for directly causing an arc discharge of a discharge lamp can be applied to the lighting circuit shown in Fig. 3.
- Fig. 14 shows a circuit arrangement of the fifth embodiment of the present invention.
- Referring to Fig. 14, a discharge lamp lighting apparatus is designed such that a boosting
inverter 130 is aDC power source 12. Theinverter 130 is constituted by a known circuit. More specifically, theinverter 130 is constituted by a pair ofMOS transistors transistors output transformer 134. - A known
voltage doubler rectifier 144 constituted bydiodes capacitors inverter 130, i.e., a secondary winding 134₂ of theoutput transformer 134. A half-bridge circuit 146 constituting alighting circuit 100₄ is connected between the two ends of a series circuit of thecapacitors voltage doubler rectifier 144. - The half-
bridge circuit 146 includes a pair ofknown MOS transistors bridge drive controller 152 for controlling a switching operation of thetransistors transistor 148 is connected to the positive terminal of thecapacitor 140, and the source of thetransistor 150 is connected to the negative terminal of thecapacitor 142. Adischarge lamp 18 is connected between the node of the source of thetransistor 148 and the drain of thetransistor 150, and the node of thecapacitors first energization detector 154, a normally-closedcontact 156m of athird relay 156, and a current limitingchoke 158. - A
starting circuit 200₆ is connected to thedischarge lamp 18 through asecond energization detector 160. Thestarting circuit 200₆ is connected to thecapacitor 140 through a normally-open contact 162m of afourth relay 162 so as to obtain an operating power source from thecapacitor 140. A capacitor incorporated in thestarting circuit 200₆ is charged in accordance with a predetermined time constant. When the charge level of the capacitor reaches a predetermined level, the capacitor is discharged, and a current including a pulse is generated by a pulse transformer as a high-voltage generator. This operation is intermittently repeated. - A
relay switching circuit 164 is connected to theDC power source 12. - For example, the
relay switching circuit 164 has an arrangement shown in Fig. 15. More specifically, a series voltage divider constituted byresistors npn transistor 306 and thefourth relay 162, and a series circuit of annpn transistor 308 and thethird relay 156 are connected to theDC power source 12. Note thatdiodes relays - The noninverting input terminal (+) of a
comparator 314 is connected to the node of theresistors resistor 316 is connected between the output terminal and the noninverting input terminal (+) of thecomparator 314. The inverting input terminal (-) of thecomparator 314 is connected to the positive electrode of thepower source 12 through a series circuit of adiode 318, aresistor 320, and aphototransistor 322T of a photocoupler 322, which constitute thesecond energization detector 160. A light-emittingdiode 322D of the photocoupler 322 is inserted in the energization path between the startingcircuit 2006 and thedischarge lamp 18. - The
first energization detector 154 includes acurrent transformer 324. A primary winding 324₁ of thetransformer 324 is inserted in the energization path between the half-bridge circuit 146 and thedischarge lamp 18. - A
resistor 326 is connected between the two ends of a secondary winding 324₂ of thecurrent transformer 324. The two ends of the secondary winding 324₂ are respectively connected to one end of acapacitor 334 throughdiodes resistor 332. In addition, an intermediate tap of the secondary winding 324₂ is connected to the other end of thecapacitor 334 and to the negative electrode of theDC power source 12. The node of thecapacitor 334 and theresistor 332 is connected to the inverting input terminal (-) of thecomparator 314 through adiode 336. - A series circuit of
resistors diode 342 and acapacitor 344 are connected between the output terminal of thecomparator 314 and the negative electrode of theDC power source 12. Thecapacitor 334 constitutes a delay circuit together with a series circuit ofresistors transistor 308 is connected to the node of theresistors transistor 306 is connected to the node of theresistors Zener diode 350. - An operation of this embodiment having such an arrangement will be described below with reference to Figs. 16A through 16I and Figs. 17A through 17I.
- When the
DC power source 12 is turned on at time t₁₁ as shown in Fig. 16A, an output from thecomparator 314 is set at high level as shown in Fig. 16B. Thetransistors third relays fourth relay 162 is closed, and the normally-closedcontact 156m of thethird relay 156 is opened. - In this manner, the
starting circuit 200₆ is connected to thepower source 12, and starts an operation. In thestarting circuit 200₆, when charging of the capacitor is started, and the charge level reaches a predetermined level a predetermined period of time T₁ (time t₁₃) after time t₁₂, a pulse shown in Fig. 16E is generated and supplied to thedischarge lamp 18. When thedischarge lamp 18 starts initial discharge, a discharge current flows upon reception of the pulse. At this time, the power supplied from thestarting circuit 200₆ is lower than the power needed for main lighting. - When this current flows, the light-emitting
diode 322D of the photocoupler 322 is operated, and thephototransistor 322T is turned on. As a result, a high-level voltage is applied to the inverting input terminal (-) of thecomparator 314 through thediode 318. The input level of the inverting input terminal (-) then becomes higher than that of the noninverting input terminal (+), and the output level of thecomparator 314 goes to low level. Subsequently, as shown in Fig. 16F, thetransistor 308 is immediately turned off at time t₁₃, and thethird relay 156 is turned off with a slight delay at time t₁₄. As a result, the normally-closedcontact 156m of therelay 156 is turned on. - In this manner, as shown in Fig. 16H, a power required for main discharge starts to be supplied from the half-
bridge circuit 146 to thedischarge lamp 18. When this current supply is started, a voltage is generated at the secondary winding 324₂ of thecurrent transformer 324, and application of a high-level voltage to the inverting input terminal (-) of thecomparator 314 is started also through thediode 336. - When an output from the
comparator 314 is set at low level, thecapacitor 344 is discharged through theresistors transistor 306 is then turned off after a lapse of a time T₂ (< T₁) (at time t₁₅) before the next pulse is generated by thestarting circuit 200₆ as shown in Fig. 16C, and thefourth relay 162 is turned off with a slight delay at time t₁₆ as shown in Fig. 16D. - In this manner, the
starting circuit 200₆ is disconnected from thepower source 12, and the current supplying operation to thedischarge lamp 18 is stopped. After time t₁₆, a current is supplied only from the half-bridge 146, and the lighting state of thedischarge lamp 18 is maintained. As a result, a lamp discharge current shown in Fig. 16I flows in thedischarge lamp 18 after the operation is started. - The above-described operation is based on the assumption that the
discharge lamp 18 is normally started. However, thedischarge lamp 18 may not be smoothly restarted. For example, thedischarge lamp 18 may not be started in response to an initial pulse, or a lighting failure may be caused after thedischarge lamp 18 is lighted. Figs. 17A through 17I are timing charts for explaining such a case. - Assume that the
DC power source 12 is turned off at time t₂₁ and is subsequently turned on again at time t₂₂ as shown in Fig. 17A. In this case, as shown in Figs. 17C and 17F, thetransistors third relays fourth relay 162 is closed, and the normally-closedcontact 156m of thethird relay 156 is opened. - Assume in this case that an initial pulse is supplied from the
starting circuit 200₆ to thedischarge lamp 18 at time t₂₄ as shown in Fig. 17E, but thedischarge lamp 18 is not started. In thestarting circuit 200₆, charging of the capacitor is started again, and a second pulse is generated after a lapse of a predetermined time T₃ (at time t₂₅). As a result, thedischarge lamp 18 is started, and thetransistor 308 is turned off, as shown in Fig. 17F. Thethird relay 156 is then turned off at time t₂₆, as shown in Fig. 17G. With this operation, the half-bridge circuit 146 is connected to thedischarge lamp 18, and a current is supplied from thecircuit 146 to thedischarge lamp 18, as shown in Fig. 17H. - Subsequently, as shown in Fig. 17C, the
transistor 306 is turned off with a delay of a predetermined period of time T₄, i.e., at time t₂₇. Thefourth relay 162 is turned off (at time t₂₈), as shown in Fig. 17D. As a result, the current supplying operation from thestarting circuit 200₆ to thedischarge lamp 18 is stopped. - If a lighting failure of the
discharge lamp 18 occurs in this state at time t₂₉ as shown in Fig. 17I, no voltage is generated at the secondary winding 324₂ of thecurrent transformer 324. Thephototransistor 322T of the photocoupler 322 has already been turned off upon operation stop of thestarting circuit 200₆. Therefore, the input level of the inverting input terminal (-) of thecomparator 314 goes to low level. As a result, the output from thecomparator 314 is inverted from low level to high level, as shown in Fig. 17B. - In response to this level change, the
transistor 306 is turned on at time t₃₀ to operate thefourth relay 162, and the normally-open contact 162m is closed to immediately operate thestarting circuit 200₆. Meanwhile, thetransistor 308 is turned on to operate thethird relay 156, and the normally-closedcontact 156m is opened to immediately disconnect the half-bridge circuit 146 from thedischarge lamp 18. - As described above, when a lighting failure of the
discharge lamp 18 occurs, thestarting circuit 200₆ is immediately operated, and the half-bridge circuit 146 is immediately disconnected from thedischarge lamp 18, thus controlling starting/lighting of thedischarge lamp 18. - When the
starting circuit 200₆ is operated to supply a current including a pulse to thedischarge lamp 18, since the half-bridge 146 equivalent to thelighting circuit 100₄ is disconnected from thedischarge lamp 18, there is no possibility that the pulse enters the half-bridge circuit 146 and damages semiconductor elements in thecircuit 146, e.g., theMOS transistors - In addition, while a current is supplied from the
starting circuit 200₆ to thedischarge lamp 18, the half-bridge circuit 146 is connected to thedischarge lamp 18 so as to start supply of a current from the half-bridge circuit 146 to thedischarge lamp 18. Thereafter, the operation of thestarting circuit 200₆ is stopped by disconnecting thecircuit 200₆ from the power source before the next pulse is generated by thecircuit 200₆. Therefore, the power supplying operations from thestarting circuit 200₆ and the half-bridge circuit 146 overlap, and the lighting operation of thedischarge lamp 18 can be stably maintained. Furthermore, even if the current supplying operations overlap, since no pulse is generated by thestarting circuit 200₆ during this period, there is no possibility that a pulse runs around and enters the half-bridge circuit 146. - In this embodiment, the energization detectors are constituted by a photocoupler, a current transformer, and the like. However, the present invention is not limited to this.
- Furthermore, in this embodiment, supply of a current from the starting circuit to the discharge lamp is stopped by disconnecting the starting circuit from the power source. However, this operation may be performed by disconnecting the starting circuit from the discharge lamp.
- Moreover, in this embodiment, the lighting circuit is constituted by the half-bridge circuit. However, the present invention is not limited to this.
Claims (11)
1. A method of lighting a discharge lamp, comprising the steps of supplying a starting high voltage, required for starting a discharge of the discharge lamp, from a starting circuit to the discharge lamp; causing the initial discharge by supplying power lower than a predetermined power from the starting circuit, after the discharge of the discharge lamp is started; and supplying a predetermined power required for main lighting of the discharge lamp from a lighting circuit to the discharge lamp, after the initial discharge is started,
characterized by further comprising the step of maintaining the initial discharge by supplying power lower than a predetermined power from the starting circuit (200), after the discharge of the discharge lamp (18) is started
characterized by further comprising the step of maintaining the initial discharge by supplying power lower than a predetermined power from the starting circuit (200), after the discharge of the discharge lamp (18) is started
2. A method according to claim 1, characterized in that said initial discharge is an arc discharge.
3. A method according to claim 1, characterized in that said initial discharge is a glow discharge.
4. A method according to claim 3, characterized in that the step of supplying the predetermined power required for main lighting includes the step of shifting the initial glow discharge to an arc discharge.
5. A method according to claim 2, characterized in that said initial discharge is a DC arc discharge.
6. A discharge lamp lighting apparatus comprising a discharge lamp; a lighting circuit, having an output terminal connected to said discharge lamp, for main lighting said discharge lamp with a predetermined electric power; and a starting circuit, connected to said discharge lamp in parallel with said lighting circuit, for applying a pulse voltage to said discharge lamp to start discharge, and causing the initial discharge with a power lower than a predetermined value after the start of the discharge,
characterized in that
said starting circuit (200) maintains the initial discharge with power lower than a predetermined value, after the discharge of discharge lamp (18) is started, and
that there is further provided a control circuit (64, 104, 116) for controlling a timing at which the output from said lighting circuit (100) is supplied to said discharge lamp (18) after said discharge lamp starts to operate and while the initial discharge is maintained.
characterized in that
said starting circuit (200) maintains the initial discharge with power lower than a predetermined value, after the discharge of discharge lamp (18) is started, and
that there is further provided a control circuit (64, 104, 116) for controlling a timing at which the output from said lighting circuit (100) is supplied to said discharge lamp (18) after said discharge lamp starts to operate and while the initial discharge is maintained.
7. An apparatus according to claim 6, characterized in that said control circuit (64, 104, 116) controls a drive starting timing of said lighting circuit (100).
8. An apparatus according to claim 6, characterized by further comprising switching means (22), connected between said discharge lamp (18) and said lighting circuit (100), for turning on/off the output from said lighting circuit (100) to said discharge lamp (18), said control circuit (64, 104, 116) controlling an ON/OFF timing of said switching means (22).
9. An apparatus according to claim 6, characterized by further comprising an impedance element (16) connected in series with said starting circuit (200) and said discharge lamp (18).
10. An apparatus according to claim 6, characterized by further comprising means for turning off said starting circuit (200) after the output from said lighting circuit (100) is supplied to said discharge lamp (18).
11. An apparatus according to claim 8, characterized by further comprising first energization detecting means (154) for detecting an energization state between said starting circuit (200) and said discharge lamp (18), second energization detecting means (160) for detecting an energization state between said lighting circuit (200) and said discharge lamp (18), said control means (164) starting a power supplying operation from said starting circuit (200) to said discharge lamp (18) and turning off said switching means (22) upon turning on of said power source, keeping said switching means ON when said first energization detecting means (154) detects an energization state, and stopping the power supplying operation from said starting circuit (200) to said discharge lamp (18) with a delay time shorter than a period of time after which a next pulse is generated by said starting circuit (200) when said second energization detecting means (160) detects an energization state and maintains the energization state.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19791889A JPH02291698A (en) | 1989-02-17 | 1989-08-01 | Lighting device for discharge lamp and method of lighting it |
JP197918/89 | 1989-08-01 | ||
JP202935/89 | 1989-08-07 | ||
JP1202935A JPH0367494A (en) | 1989-08-07 | 1989-08-07 | Lighting device for electric discharge lamp |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0411617A2 true EP0411617A2 (en) | 1991-02-06 |
EP0411617A3 EP0411617A3 (en) | 1992-05-13 |
Family
ID=26510652
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19900114791 Withdrawn EP0411617A3 (en) | 1989-08-01 | 1990-08-01 | Method of lighting discharge lamp and discharge lamp lighting apparatus |
Country Status (1)
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EP (1) | EP0411617A3 (en) |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1993004569A1 (en) * | 1991-08-23 | 1993-03-04 | Robert Bosch Gmbh | Device for operating a gas-discharge lamp |
EP0540924A1 (en) * | 1991-11-06 | 1993-05-12 | Hella KG Hueck & Co. | Ballast for starting and operating high pressure discharge lamps |
EP0647085A1 (en) * | 1993-09-30 | 1995-04-05 | MAGNETI MARELLI S.p.A. | A control circuit for a gas-discharge lamp, particularly for motor vehicles |
US5463281A (en) * | 1991-11-13 | 1995-10-31 | U.S. Philips Corporation | Circuit arrangement for operating a high-pressure discharge lamp |
EP0684755A1 (en) * | 1994-05-26 | 1995-11-29 | MAGNETI MARELLI S.p.A. | A supply circuit for a gas-discharge lamp, particularly for motor vehicles |
EP0715487A3 (en) * | 1994-12-02 | 1996-08-14 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Process and circuit for starting and operating high pressure discharge lamps |
EP0732869A2 (en) * | 1995-03-17 | 1996-09-18 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Process and circuit for operating a discharge lamp |
EP0740494A2 (en) * | 1995-04-27 | 1996-10-30 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Electrical circuit for the pulsed operation of discharge lamps |
DE19608649C1 (en) * | 1996-03-06 | 1997-05-28 | Bosch Gmbh Robert | Device for recognition of firing of high pressure gas discharge lamp for car headlamp |
EP0794695A1 (en) * | 1996-03-06 | 1997-09-10 | Robert Bosch Gmbh | Circuit for operating a high pressure discharge lamp |
EP0933978A1 (en) * | 1998-01-30 | 1999-08-04 | Bureau d'Etudes Eclairage Public B.E.E.P. | Starter for discharge lamps |
EP0946081A1 (en) * | 1998-03-27 | 1999-09-29 | Valeo Vision | Device for operating a discharge lamp in a vehicle headlamp |
WO2000045622A1 (en) * | 1999-01-29 | 2000-08-03 | Electro-Mag International, Inc. | Hid ballast with hot restart circuit |
WO2004064457A1 (en) * | 2003-01-14 | 2004-07-29 | Koninklijke Philips Electronics N.V. | Circuit arrangment |
EP1517590A2 (en) * | 2003-09-18 | 2005-03-23 | Toshiba Lighting & Technology Corporation | Starting unit for use in a high intensity discharge lamp lighting device |
WO2006064408A1 (en) * | 2004-12-14 | 2006-06-22 | Koninklijke Philips Electronics N.V. | Hf gas discharge lamp circuit |
WO2010013166A1 (en) * | 2008-07-31 | 2010-02-04 | Koninklijke Philips Electronics N.V. | Gas discharge lamp driver and method |
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Cited By (30)
Publication number | Priority date | Publication date | Assignee | Title |
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US5506479A (en) * | 1991-08-23 | 1996-04-09 | Robert Bosch Gmbh | Device for operating a gas-discharge lamp |
WO1993004569A1 (en) * | 1991-08-23 | 1993-03-04 | Robert Bosch Gmbh | Device for operating a gas-discharge lamp |
EP0540924A1 (en) * | 1991-11-06 | 1993-05-12 | Hella KG Hueck & Co. | Ballast for starting and operating high pressure discharge lamps |
US5463281A (en) * | 1991-11-13 | 1995-10-31 | U.S. Philips Corporation | Circuit arrangement for operating a high-pressure discharge lamp |
EP0647085A1 (en) * | 1993-09-30 | 1995-04-05 | MAGNETI MARELLI S.p.A. | A control circuit for a gas-discharge lamp, particularly for motor vehicles |
US6140770A (en) * | 1993-09-30 | 2000-10-31 | Marelli Autornica S.P.A. | Ballast for a gas-discharge lamp, particularly for motor vehicles |
EP0684755A1 (en) * | 1994-05-26 | 1995-11-29 | MAGNETI MARELLI S.p.A. | A supply circuit for a gas-discharge lamp, particularly for motor vehicles |
US5821696A (en) * | 1994-12-02 | 1998-10-13 | Patent-Treuhand Gesellschaft F. Elektrische Gluehlampen Mbh | Method and circuit to start and operate high pressure discharge lamps |
EP0715487A3 (en) * | 1994-12-02 | 1996-08-14 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Process and circuit for starting and operating high pressure discharge lamps |
EP0732869A2 (en) * | 1995-03-17 | 1996-09-18 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Process and circuit for operating a discharge lamp |
US5770924A (en) * | 1995-03-17 | 1998-06-23 | Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen Mbh | Ignitional run circuit that immediately applies only a DC voltage after lamp ignition but before the main AC potential is applied |
EP0732869A3 (en) * | 1995-03-17 | 1997-03-12 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Process and circuit for operating a discharge lamp |
EP0740494A3 (en) * | 1995-04-27 | 2003-11-05 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Electrical circuit for the pulsed operation of discharge lamps |
EP0740494A2 (en) * | 1995-04-27 | 1996-10-30 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Electrical circuit for the pulsed operation of discharge lamps |
EP0794695A1 (en) * | 1996-03-06 | 1997-09-10 | Robert Bosch Gmbh | Circuit for operating a high pressure discharge lamp |
US5965986A (en) * | 1996-03-06 | 1999-10-12 | Robert Bosch Gmbh | Arrangement for detecting the ignition of a high-pressure gas discharge lamp |
DE19608649C1 (en) * | 1996-03-06 | 1997-05-28 | Bosch Gmbh Robert | Device for recognition of firing of high pressure gas discharge lamp for car headlamp |
EP0933978A1 (en) * | 1998-01-30 | 1999-08-04 | Bureau d'Etudes Eclairage Public B.E.E.P. | Starter for discharge lamps |
FR2774547A1 (en) * | 1998-01-30 | 1999-08-06 | Eclairage Public Beep Bureau E | PRIMING DEVICE FOR POWERING ARC LAMPS |
EP0946081A1 (en) * | 1998-03-27 | 1999-09-29 | Valeo Vision | Device for operating a discharge lamp in a vehicle headlamp |
FR2776887A1 (en) * | 1998-03-27 | 1999-10-01 | Valeo Vision | DEVICE FOR SUPPLYING A MOTOR VEHICLE PROJECTOR DISCHARGE LAMP |
US6075327A (en) * | 1998-03-27 | 2000-06-13 | Valeo Vision | Power supply apparatus for a discharge lamp, especially for a motor vehicle headlight |
WO2000045622A1 (en) * | 1999-01-29 | 2000-08-03 | Electro-Mag International, Inc. | Hid ballast with hot restart circuit |
US6194843B1 (en) | 1999-01-29 | 2001-02-27 | Electro-Mag International, Inc. | HID ballast with hot restart circuit |
WO2004064457A1 (en) * | 2003-01-14 | 2004-07-29 | Koninklijke Philips Electronics N.V. | Circuit arrangment |
US7170235B2 (en) | 2003-01-14 | 2007-01-30 | Koninklijke Philips Electronics N.V. | Circuit arrangement with a separate resonant igniter for a high-pressure discharge lamp |
EP1517590A2 (en) * | 2003-09-18 | 2005-03-23 | Toshiba Lighting & Technology Corporation | Starting unit for use in a high intensity discharge lamp lighting device |
EP1517590A3 (en) * | 2003-09-18 | 2008-01-16 | Toshiba Lighting & Technology Corporation | Starting unit for use in a high intensity discharge lamp lighting device |
WO2006064408A1 (en) * | 2004-12-14 | 2006-06-22 | Koninklijke Philips Electronics N.V. | Hf gas discharge lamp circuit |
WO2010013166A1 (en) * | 2008-07-31 | 2010-02-04 | Koninklijke Philips Electronics N.V. | Gas discharge lamp driver and method |
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