JP4749376B2 - Discharge lamp lighting device and lighting device - Google Patents

Description

  The present invention relates to a discharge lamp lighting device that performs high-frequency lighting using an inverter circuit and a lighting device including the discharge lamp lighting device, and particularly relates to a device that eliminates power loss and realizes energy saving.

  In general, when a hot cathode type discharge lamp is lit, it is necessary to preheat the filament of the discharge lamp before the discharge lamp is lit, and therefore a filament preheating current (hereinafter referred to as preheating current) is supplied to the filament. Therefore, in the discharge lamp lighting device, a filament preheating transformer is connected to the output of the inverter circuit. The filament of the discharge lamp is connected to the secondary winding of the filament preheating transformer. When the power is turned on, a high-frequency voltage is applied to the filament preheating transformer, and a preheating current is supplied to the filament to preheat it. After the preheating is completed, the discharge lamp starts to be lit. However, after the discharge lamp is lit, the filament is heated by the discharge current flowing through the discharge lamp, so that the preheating current from the filament preheating transformer is unnecessary.

  However, even after the discharge lamp is lit, the output voltage of the inverter is applied to the filament preheating transformer and the preheating current is supplied to the filament, resulting in power loss. Therefore, in the conventional discharge lamp lighting device, a switch element is connected in series to the primary winding of the filament preheating transformer, and after lighting, the switch element is turned off to supply the primary winding of the filament preheating transformer. Cut off current. As a result, the supply of the preheating current to the filament is blocked, so that the power loss due to the filament can be reduced. (For example, see Patent Document 1)

  Further, in the conventional half-bridge type discharge lamp lighting device, a switching current is detected by inserting a resistor between the source of the switching element (for example, MOSFET) on the low voltage side and GND, and the discharge is performed based on the detection signal of the switching current. It performs feedback control of power input to the lamp.

  When a filament preheating circuit is provided in this conventional half-bridge type discharge lamp lighting device, when the preheating current is interrupted during lighting of the discharge lamp, it is supplied to a load circuit comprising a ballast coil, a resonance capacitor, and a discharge lamp. Current can be detected from the switching current, so that desired power can be supplied to the discharge lamp. However, when the preheating current is supplied during lighting of the discharge lamp, the value obtained by adding the current flowing through the preheating circuit to the current of the load circuit consisting of the ballast coil, the resonance capacitor, and the discharge lamp is detected from the switching current. When feedback control is performed in this state, the power supplied to the discharge lamp becomes smaller than the desired power. For this reason, the discharge lamp may go out.

  In order to solve this problem, after the discharge lamp is turned on until the filament current is turned off, the feedback circuit is masked to shut off the preheating current, and then the feedback control is started (for example, Patent Documents). 2).

JP 2001-351790 (paragraph 0024, FIG. 1 and FIG. 2) Japanese Patent Laying-Open No. 2005-19142 (paragraphs 0092 and 0095, FIGS. 14 and 15)

  In the conventional circuit-type discharge lamp lighting device that cuts off the preheating current as described above and reduces the preheating power of the filament, if the current of the discharge lamp is reduced by dimming control and the luminous flux is reduced, the discharge current of the discharge lamp decreases. As a result, the filament temperature decreases. In this case, a preheat current must be supplied again because it enters a region where the emitter (electron emitting material) is scattered, which is called a scattering region, and causes early blackening and short life. However, if a preheating current is supplied during dimming, a value obtained by adding the current flowing through the filament preheating circuit to the load circuit current consisting of the ballast coil, resonant capacitor, and discharge lamp is detected from the switching current. Thus, when feedback control of the input power to the discharge lamp is performed, the power input to the discharge lamp becomes smaller than the desired power.

  The present invention has been made to solve the above-described problems, achieves energy saving in all-light lighting or a state close thereto, supplies a preheating current during dimming, performs appropriate discharge lamp power feedback, An object of the present invention is to obtain a discharge lamp lighting device and a lighting device that can prevent the lamp from disappearing and extend the life of the discharge lamp.

  A discharge lamp lighting device according to the present invention converts power supplied from a power source into high-frequency power and preheats a filament of the discharge lamp in a discharge lamp lighting device using an inverter circuit for lighting a connected discharge lamp. A filament preheating transformer for supplying a preheating current for the filament, and a switch element connected in series with the filament preheating transformer and controlling the supply of the preheating current to the filament connected to the secondary side of the filament preheating transformer by opening and closing (Hereinafter referred to as a preheating switch), detecting means for detecting the current flowing through the switching element of the inverter circuit, comparing the detection signal of the detecting means and the target value current to adjust the switching frequency of the inverter circuit, and the target current value Feedback means to bring it closer to the target current value during preheating current supply. It is characterized in adding a current value equivalent to.

  According to the discharge lamp lighting device of the present invention, the preheating switch is turned on during dimming lighting to supply the preheating current to the filament, and during the preheating current supply, the preheating current is supplied to the target current value of the current flowing through the switching element of the inverter circuit. Since the current value corresponding to the minute is added, it is possible to prevent the electric power supplied to the discharge lamp by feedback control from becoming smaller than the desired discharge lamp electric power. Accordingly, appropriate discharge lamp power feedback is possible, and it is possible to prevent extinction and to prolong the life of the discharge lamp by supplying a preheating current during dimming lighting.

Embodiment 1 FIG.
1 is a diagram showing a configuration of a discharge lamp lighting device according to Embodiment 1 of the present invention.
In FIG. 1, a discharge lamp lighting device includes a commercial AC power source 1, a rectifier circuit 2 that full-wave rectifies the AC of the commercial AC power source 1, and a boost chopper circuit 3 that boosts a DC voltage that has been full-wave rectified by the rectifier circuit 2. A smoothing capacitor 4 for smoothing the DC voltage from the step-up chopper circuit 3, and a half-bridge inverter circuit composed of switching elements 5a and 5b connected in parallel to the smoothing capacitor 4 to convert the DC voltage into a high frequency, and driving the switching elements 5a and 5b A driver 6, a ballast coil 7 connected to the output of the inverter circuit, a load circuit composed of a discharge lamp 8 and a resonance capacitor 9, and a DC cut capacitor 10.

  Furthermore, in this embodiment, the shunt resistor 11 connected in series with the source terminal of the low-side switching element (for example, MOSFET) and detecting the switching current, the switching current flowing through the shunt resistor 11 is detected, and the detected detection signal An inverter control circuit 12 having feedback control means for comparing the target switching current value and controlling the switching frequency so as to approach the target value, a filament preheating transformer 13 connected in parallel with the load circuit and the DC cut capacitor 10, preheating A series circuit of a switch 14 and a DC cut capacitor 15, a preheating switch control circuit 16 for controlling on / off of the preheating switch, and a dimming controller 17 for outputting a dimming signal to the inverter control circuit 12 are provided.

  In the first embodiment, the preheating current is cut off at the time of all light or near all light by controlling on / off of the preheating switch 14 connected in series with the primary winding of the filament preheating transformer 13. Reduces power loss due to the filament, prevents premature discharge of the lamp by reducing the life of the discharge lamp during dimming, and further controls the inverter circuit's switching element during preheating current supply during discharge lamp power feedback control during dimming The switching current value corresponding to the preheating current supply is added to the target current value of the current flowing through the lamp to prevent the power supplied to the discharge lamp from becoming smaller than the desired lamp power and to prevent the lamp from going out.

  Next, the operation of the discharge lamp lighting device according to Embodiment 1 of the present invention will be described with reference to FIGS. When the commercial AC power source 1 is turned on, the commercial AC power source 1 is rectified by the rectifier circuit 2, boosted by the step-up chopper circuit 3, and further smoothed by the smoothing capacitor 4. The elements 5a and 5b are alternately turned on and off to convert to high frequency voltage. The inverter control circuit 12 performs on / off control of the switching elements 5a and 5b.

  After the power is turned on and before the discharge lamp 8 is turned on, the inverter control circuit 12 enters a preheating mode in which the filaments 8a and 8b are preheated and controls the switching elements 5a and 5b of the inverter circuit. At this time, the preheating switch control circuit 16 makes the preheating switch 14 turn on. Accordingly, a high-frequency voltage is applied to the primary winding of the filament preheating transformer 13 by high-frequency switching of the switching elements 5a and 5b, thereby supplying a preheating current to the filaments 8a and 8b connected to the secondary winding of the filament preheating transformer. (FIG. 2 (a)) and preheating is performed.

  When preheating of the filaments 8a and 8b is completed due to the passage of time or the like, the inverter control circuit 12 switches from the preheating mode to the start mode in order to light the discharge lamp 8, and controls the inverter circuit in the start mode. Here, the start mode is a mode in which the switching frequency of the inverter circuit is brought close to the resonance frequency of the ballast coil 7 and the resonance capacitor 9. When the switching frequency by the inverter circuit approaches the resonance frequency, a high voltage is applied between the filaments 8a and 8b of the discharge lamp 8 (FIG. 2 (b)), discharge starts and the lighting mode is entered, and the discharge lamp 8 is turned on. To do.

  After lighting the discharge lamp 8, in the lighting mode, the inverter control circuit 12 starts feedback control using a built-in feedback control means (not shown) in order to make the discharge lamp 8 have a dimming degree corresponding to the dimming signal. When the input power to the discharge lamp 8 is fed back, the shunt resistor 11 detects the switching current flowing through the shunt resistor 11 connected to the source terminal of the low-side switching element 5b (eg, MOSFET) of the inverter circuit, and this is detected by the inverter. Send to control circuit 12. The inverter control circuit 12 compares the target current value determined by the dimming signal with the feedback control means and the switching current value detected by the shunt resistor 11, and changes the switching frequency of the inverter so that they match. Here, when the dimming signal outputs a signal indicating the state of all light or a state close to all light, the filament is heated to an appropriate temperature by the discharge current of the discharge lamp. When a dimming signal indicating all light or a state close to all light is received via the inverter control circuit 12, the preheating switch 14 is turned off, the preheating current is cut, and power loss due to the filament is reduced (FIG. 2 ( a)).

  Next, when an instruction to lower the luminous flux by reducing the power of the discharge lamp by the dimming signal is output, the discharge current of the discharge lamp becomes small, so that the proper temperature of the filament cannot be maintained only by the discharge current. Therefore, when the preheating switch control circuit 16 receives the dimming signal from the dimming controller 17 to reduce the power of the discharge lamp and to reduce the luminous flux through the inverter control circuit 12, the preheating switch 14 is turned on, and the filament transformer A preheating current is supplied from the secondary side of 13 to achieve stable lighting of the discharge lamp and prevention of life reduction.

  Here, when the preheating switch 14 is turned on at the time of dimming and the preheating current is supplied, the switching current flowing through the shunt resistor 11 is changed to the current of the load circuit including the ballast coil 7, the discharge lamp 8, and the resonance capacitor 9. Therefore, when feedback control is performed, the power supplied to the discharge lamp is smaller than the desired power. Therefore, when supplying the preheating current, the inverter control circuit 12 adds a current value corresponding to the preheating current supply to the target current value as shown by a broken line in FIG. As a result, even if the current flowing through the shunt resistor 11 is increased by supplying the preheating current, the target current value is increased accordingly, so that the power can be prevented from becoming smaller than a desired value. Therefore, appropriate discharge lamp power feedback can be achieved, and the life of the discharge lamp can be extended by preventing the extinction and supplying the preheating current during dimming.

  As described above, an inverter circuit that converts a DC voltage into a high frequency and applies the high frequency voltage to the discharge lamp, a load circuit that includes the ballast coil 7, the discharge lamp 8, and the resonant capacitor 9 connected to the output of the inverter circuit; A shunt resistor 11 for detecting a switching current in series with the source terminal of the low-side switching element b (for example, MOSFET), a current flowing through the shunt resistor 11 are detected, and the detected signal is compared with a target current value, An inverter control circuit 12 having a feedback control means for controlling the switching frequency so as to approach the value, and a filament preheating transformer 13, a preheating switch 14 and a DC cut capacitor 15 connected in parallel with the load circuit and the DC cut capacitor 10. The circuit and the preheat control that controls the on / off of the preheat switch And a switch control circuit 16 for controlling on / off of the preheating switch 14 so that the preheating current is cut off at the time of all light or in a state close to all light to reduce the power loss due to the filament, and the preheating current at the time of dimming. Is used to prevent the life of the discharge lamp from deteriorating and achieve stable lighting.

  In the discharge lamp power feedback control at the time of dimming, during the preheating current supply, the current value corresponding to the preheating current supply is added to the target current value of the current flowing through the switching element of the inverter circuit, and is supplied to the discharge lamp. It is possible to prevent the power from becoming smaller than a desired discharge lamp power, and to prevent the power from going off.

  Therefore, the discharge lamp lighting device of the first embodiment can cut off the preheating current with a simple circuit configuration when all the lights are lit, achieve energy saving, and supply the preheating current at the time of dimming, and appropriate discharge lamp power feedback. Control can be performed to prevent extinction and to extend the life of the discharge lamp.

Embodiment 2. FIG.
FIG. 3 is a lighting sequence diagram of the discharge lamp lighting device according to Embodiment 2 of the present invention. Since the second embodiment has the same circuit configuration as the discharge lamp lighting device shown in FIG. 1 of the first embodiment, the description thereof is omitted.

  In the discharge lamp lighting device of FIG. 1, the second embodiment disables the feedback control for a predetermined period after the discharge lamp is lit, fixes the switching frequency of the inverter during the predetermined period, and turns on and off the preheating switch 14 respectively. The current is detected by the switching current detecting means during the period. The switching current value corresponding to the preheating current supply when the preheating switch 14 is turned on can be obtained by taking the difference between the detected current values. Thus, in the discharge lamp power feedback control during dimming, during the preheating current supply, the switching current value corresponding to the preheating current supply is added to the target current value of the switching current of the inverter circuit determined by the dimming signal. Thus, the electric power supplied to the discharge lamp is prevented from becoming smaller than the desired discharge lamp electric power, and the turn-off is prevented.

  Next, the operation of the discharge lamp lighting device will be described with reference to FIG. Here, the description of the same parts as those in Embodiment 1 is omitted. After the power is turned on, the inverter control circuit 12 uses the built-in feedback control means after the discharge lamp is lit in the start mode in which the start voltage is applied to the discharge lamp through the pre-heating of the filament (FIG. 3, pre-heating mode). ), The power feedback of the discharge lamp is invalidated for a predetermined period. The preheating switch 14 is in an ON state and a preheating current is supplied. At this time, the switching frequency of the inverter circuit is fixed and oscillates. Here, the value of the current flowing through the shunt resistor 11 is detected while the preheating switch 14 is on (FIG. 3 (a) switching current detection point 1). Next, the preheating switch control circuit 16 turns off the preheating switch 14 and cuts off the preheating current. After the preheating current is interrupted, the current value flowing through the shunt resistor 11 is detected again (FIG. 3 (a) switching current detection point 2). The inverter control circuit 12 obtains a switching current value corresponding to a preheating current supply when the preheating switch 14 is turned on by obtaining a difference between a detected current value when the preheating switch 14 is turned on and a detected current value when the preheating switch 14 is turned off. Can do.

  Next, the inverter control circuit 12 starts feedback control to obtain a dimming degree corresponding to the dimming signal using the feedback control means. Further, the inverter control circuit 12 detects the switching current flowing through the shunt resistor 11 using the feedback control means, compares it with the target current value determined by the dimming signal, and changes the switching frequency of the inverter so that they match. . Here, when the dimming signal outputs a signal that indicates all light or a state close to all light, since the filament is heated to an appropriate temperature by the discharge current of the discharge lamp, the preheating switch control circuit 16 sets the preheating switch 14. Turn off and cut power loss due to filament.

  When the dimming controller 17 reduces the discharge lamp power and outputs a dimming signal that lowers the luminous flux, the discharge current of the discharge lamp becomes small. Therefore, the appropriate temperature of the filament cannot be maintained only by the discharge current. Therefore, the preheating switch control circuit 16 turns on the preheating switch 14 and supplies a preheating current from the secondary side of the filament preheating transformer 13 to prevent the life of the discharge lamp from being reduced. At this time, the target value of the switching current is set to the target value determined according to the dimming signal as shown in FIG. 3 (d), and the detection current value when the preheating switch is on and the detection current when the preheating switch is off. This is a value obtained by adding a switching current value corresponding to a preheating current supply which is a difference in value. As a result, it is possible to prevent the discharge lamp power from becoming smaller than the desired discharge lamp power at the time of supplying the preheating current, to enable appropriate discharge lamp power feedback control, and to prevent the discharge lamp from extinguishing.

  As described above, after the discharge lamp is turned on, the feedback control is disabled for a predetermined period, the switching frequency of the inverter is fixed for the predetermined period, and the current is detected by the shunt resistor 11 in each period when the preheating switch 14 is turned on and off. The switching current value corresponding to the preheating current supply when the preheating switch is turned on can be obtained by taking the difference between the detected current values, and in the power feedback control of the discharge lamp during dimming, the preheating current During supply, since the switching current value corresponding to the preheating current supply is added to the target current value of the switching current of the inverter circuit determined by the dimming signal, the power supplied to the discharge lamp becomes smaller than the desired power This prevents the disappearance.

  Therefore, the discharge lamp lighting device of the second embodiment can cut off the filament preheating current with a simple circuit configuration, achieve energy saving, supply the preheating current during dimming, and perform appropriate discharge lamp power feedback control, It is intended to prevent extinction and prolong the life of the discharge lamp.

Embodiment 3 FIG.
The third embodiment is the same as the configuration of FIG. 1 of the first embodiment except that the operation is changed, and the operation will be described.

  In the third embodiment, the preheating current corresponding to the dimming degree is supplied without changing the circuit, so that the life of the discharge lamp can be prevented from being reduced and the energy can be saved with a simple circuit configuration.

  FIG. 4 shows a preheating current control system for a discharge lamp lighting device according to Embodiment 3 of the present invention. The operation of the third embodiment will be described. Here, the description of the same parts as those in Embodiment 1 is omitted. After the power is turned on, the discharge lamp starts to light through the pre-heating of the filament. When the dimming controller 17 outputs a signal indicating the state of all light or a state close to all light, the preheating switch control circuit 16 turns off the preheating switch 14 because the filament is heated to an appropriate temperature by the discharge current of the discharge lamp. And cut the power loss due to the filament.

  When a signal for reducing the power of the discharge lamp and reducing the luminous flux is output by the dimming controller 17, the discharge current of the discharge lamp becomes small, so that the appropriate temperature of the filament cannot be maintained only by the discharge current. Accordingly, when the preheating switch control circuit 16 receives a dimming signal from the dimming controller 17 to reduce the power of the discharge lamp via the inverter control circuit 12, the preheating switch is turned on and the filament transformer secondary side is turned on. Supply preheating current. Here, for example, when the dimming degree is continuously controlled, the preheating current needs to be supplied to the filament in accordance with the dimming degree in order to keep the filament temperature appropriate.

  Therefore, as shown in FIG. 4, the preheating switch control circuit 16 performs duty control of the preheating switch 14 at, for example, about 1 kHz, the dimming degree is deep, that is, the duty ratio is increased as the discharge current is reduced, and a large preheating current is applied to the filament. Supply. FIG. 5 shows the preheating current waveform and the control signal of the preheating switch 14, and the sequence diagram from the preheating mode of the preheating current is after dimming lighting of the preheating current of FIG. 2 (a) or FIG. 3 (a). The part of FIG. 2 (the right side of FIG. 2A or the right side of FIG. 3A) is replaced with this FIG. Thus, in the region where the dimming degree is deep, the preheating current is increased by increasing the on-duty of the preheating switch 14. As a result, the preheating current is increased to maintain the filament temperature at an appropriate value in a region where the dimming level is deep, i.e., the discharge current is small, and the life of the discharge lamp is prevented from being reduced. And cut the excess power consumption.

  As described above, duty control of the preheating switch 14 and supply of an optimal preheating current according to the dimming degree can prevent the life of the discharge lamp from decreasing and save energy.

Embodiment 4 FIG.
In the fourth embodiment, the operation is changed in the same manner as the configuration of FIG. 1 of the first embodiment. FIG. 3 is also used in the fourth embodiment. The fourth embodiment is a discharge lamp lighting device according to the third embodiment that supplies a preheating current according to the dimming degree, and a target current value of a current that flows through the switching element of the inverter circuit during discharge lamp power feedback control during dimming. In addition, the current value corresponding to the preheating current supply amount is added to prevent the electric power supplied to the discharge lamp from becoming smaller than the desired electric power and to prevent the lamp from going out.

FIG. 6 is a diagram showing the relationship between the target value of switching current and the average preheating corresponding to the dimming degree of the discharge lamp lighting device according to Embodiment 4 of the present invention.
Next, the operation will be described with reference to FIGS.
As in the second embodiment, after the discharge lamp is lit, the inverter control circuit 12 disables the feedback control for a predetermined period using the feedback control means, and the switching frequency of the inverter is fixed during the predetermined period, and the preheating switch 14 is turned on and off. Current detection is performed by the shunt resistor 11 in each period. The switching current value corresponding to the preheating current supply when the preheating switch is turned on can be obtained by taking the difference between the detected current values.

  Next, the discharge lamp power feedback control is enabled, and the discharge lamp power is controlled according to the dimming signal. When the dimming controller 17 outputs a signal instructing all light or a state close to all light, the filament is heated to an appropriate temperature by the discharge current of the discharge lamp, so the preheating switch control circuit 16 turns off the preheating switch 14. Cut the power loss due to the filament.

  When the dimming controller 17 reduces the discharge lamp power and outputs a dimming signal that lowers the luminous flux, the discharge current of the discharge lamp becomes small, so that the appropriate temperature of the filament cannot be maintained only by the discharge current. Therefore, the preheating switch control circuit 16 turns on the preheating switch 14 and supplies a preheating current from the secondary side of the filament preheating transformer 13. Here, as shown in the third embodiment, the preheating switch 14 is duty-controlled, the dimming degree is deep, that is, the duty ratio is increased as the current of the discharge lamp is decreased, and a large preheating current is supplied to the filament. At this time, the inverter control circuit 12 adds a current value corresponding to the preheating current supply to the target current value of the switching current detected by the shunt resistor 11 in FIG. 1, and the power supplied to the discharge lamp is greater than the desired power. Although the amount of preheating current is different depending on the dimming degree, the current value to be added to the switching current target value increases as the average preheating current increases as shown in FIG.

  The broken line shown in FIG. 6 is a switching current target value when the preheating current is not considered. It can be seen that the solid line switching current target value increases in proportion to the increase of the average preheating current with respect to the broken line switching current target value. In other words, since the preheating current is proportional to the duty ratio of the preheating switch, the current value to be added to the target value is obtained by taking the product of the switching current value corresponding to the preheating current supply obtained after the discharge lamp is lit and the duty ratio of the preheating switch. Ask. Thus, in the discharge lamp power feedback control during dimming, during the preheating current supply, the current value corresponding to the preheating current supply is added to the target current value of the switching current of the inverter circuit determined by the dimming signal. This prevents the electric power supplied to the discharge lamp from becoming smaller than the desired electric power and prevents the lamp from going out.

  As described above, the preheating switch is duty controlled, the optimum preheating current is supplied in accordance with the dimming degree, and the switching current target value is adjusted in accordance with the amount of preheating current supply so that the electric power supplied to the discharge lamp is desired. It is possible to prevent the electric power from becoming smaller than the electric power, to prevent the lamp from turning off, to prevent the life of the discharge lamp from being reduced, and to achieve energy saving.

Embodiment 5 FIG.
The fifth embodiment is the same as the configuration of FIG. 1 of the first embodiment except that the operation is changed, and the operation will be described.

  In the discharge lamp lighting device according to the fifth embodiment, after the power is turned on, the discharge lamp is lit after the preliminary preheating of the filament, and the power control of the discharge lamp is started. Alternatively, when a signal indicating a state close to all light is output, since the filament is heated to an appropriate temperature by the discharge current of the discharge lamp, the preheating switch control circuit 16 turns off the preheating switch 14 and cuts power loss due to the filament. To do. At this time, turning off the preheating current instantaneously flickers or disappears instantaneously, adversely affects the discharge lamp filament, and shortens the service life. Therefore, when the dimming controller 17 outputs a signal indicating an all-light or near-all-light state and turns off the preheating current, the preheating switch control circuit 16 does not instantaneously turn off the preheating current as shown in FIG. The preheating switch is gradually reduced from a state where the duty ratio is 100%, and finally the duty ratio is set to 0% to completely cut off the preheating current.

  As a result, it is possible to prevent an instantaneous flicker when the preheating current is turned off and an adverse effect on the filament. Therefore, it is possible to prevent the discharge lamp from turning off, to prevent the discharge lamp from being shortened, and to save energy.

Embodiment 6 FIG.
In the sixth embodiment, the operation is changed in the discharge lamp lighting device shown in the first embodiment, and the operation will be described.

  In the discharge lamp lighting device shown in the fifth embodiment, the sixth embodiment starts the power feedback of the discharge lamp after the discharge lamp is lit, and the dimming controller 17 indicates a state indicating all light or a state close to all light. Since the filament is heated to an appropriate temperature by the discharge current of the discharge lamp, the preheating switch control circuit 16 turns off the preheating switch 14 and cuts power loss due to the filament. At this time, the preheating switch control circuit 16 does not instantaneously turn off the filament current in the same manner as in the fifth embodiment, and gradually decreases the duty ratio from the state of the duty ratio of 100%, and finally the duty ratio. The preheating current is completely cut off as 0%.

  Here, during the period in which the duty ratio of the preheating switch is gradually decreased from 100%, the switching current detected by the shunt resistor 11 decreases as the duty ratio decreases. Therefore, during this period, the electric power supplied to the discharge lamp does not become the desired electric power, causing an instantaneous flicker when the preheating switch is turned off. Therefore, in order to prevent this, as shown in FIG. 8B, the inverter control circuit 12 switches the current detected by the shunt resistor 11 in FIG. 1 during the period in which the duty ratio of the preheating switch is gradually reduced. As the duty ratio decreases in synchronization with this target current value, the switching current target value is also reduced by an amount corresponding to the preheating current supply. By taking the product of the switching current value corresponding to the preheating current supply obtained in the second embodiment and the duty ratio of the preheating switch, the product is added to the corresponding switching current target value. As shown in FIG. 8, the duty ratio decreases with time, and the switching current target value also decreases accordingly.

  In this way, the switching current target value is set in consideration of the preheating current even during the preheating current interruption period, so that the electric power supplied to the discharge lamp becomes a desired value, preventing the flickering and extinguishing of the discharge lamp, and the life of the discharge lamp. Prevention of decline and energy saving can be achieved.

Embodiment 7 FIG.
In the seventh embodiment, the operation is changed in the same manner as the configuration of FIG. 1 of the first embodiment. In the seventh embodiment, as in the second embodiment, current detection is performed by the shunt resistor 11 of FIG. 1 in each period when the preheating switch 14 is turned on and off after the discharge lamp is turned on. The switching current value corresponding to the preheating current supply when the preheating switch is turned on is obtained by taking the difference between the detection values. At this time, if the obtained current value is outside the predetermined range, the discharge lamp is abnormal. Judgment is made, and the inverter operation is stopped to protect the inverter circuit.

  FIG. 9 shows a timing chart regarding a series of operations after power-on. After the power is turned on and the discharge lamp is turned on in the start mode after the preceding preheating period (preheating mode), the inverter control circuit 12 disables the feedback control for a predetermined period, thereby fixing the switching frequency of the inverter for the predetermined period. As shown in FIG. 9A, the switching current detection is performed by the shunt resistor 11 of FIG. 1 in each period when the preheating switch 14 is turned on and off. Next, the inverter control circuit 12 takes the difference between the detected values. From this, the current value corresponding to the preheating current supply when the preheating switch is on is obtained. Here, if the detected value of the switching current obtained is outside the predetermined range, the inverter control circuit 12 determines that the discharge lamp is abnormal and stops the inverter operation. If the obtained current value is within the predetermined range, the power feedback control of the discharge lamp is started, and the power of the discharge lamp is controlled according to the dimming signal.

  In this way, after the discharge lamp is lit, the switching current is detected by the shunt resistor 11 in each period when the preheating switch 14 is turned on and off, and the difference between the detected values is taken to obtain the preheating current supply when the preheating switch is turned on. The corresponding switching current value is obtained, and if it is outside the predetermined range, it is determined that the discharge lamp is abnormal, and the inverter operation is stopped, so that the inverter circuit can be protected.

Embodiment 8 FIG.
In the eighth embodiment, after the discharge lamp is turned on, the switching current is detected in each period when the preheating switch is turned on and off, and the difference between the detected current values is taken. In Embodiment 7 where the inverter operation is stopped, when it is determined that the discharge lamp is abnormal and the inverter operation is stopped, information to that effect is output to a display device or the like to inform the user and prompt the user to replace the discharge lamp. is there.

  As in the seventh embodiment, immediately after the power is turned on and the discharge lamp is lit, the inverter control circuit 12 detects the current from the shunt resistor 11 in FIG. 1 during each period when the preheating switch is on and off. The difference between the detected values is taken. From this, the switching current value corresponding to the preheating current supply when the preheating switch is on is obtained. Here, if the obtained current value is outside the predetermined range, it is determined that the discharge lamp is abnormal, and the inverter operation is stopped. At this time, the display device attached to the lighting fixture or the dimming controller, for example, the LED is turned on to notify the user of the discharge lamp abnormality and prompt the user to replace the discharge lamp.

In this way, when the discharge lamp is abnormal, the display device, for example, the LED is lit to notify the user of the discharge lamp abnormality and prompt the user to replace the discharge lamp, thereby facilitating maintenance of the user's lighting fixture.
The display device for abnormal discharge lamps is not limited to display when the preheating current is outside the predetermined range. In the case of other abnormal discharge lamps such as abnormal discharge lamp voltage, abnormal discharge lamp current, emiless lamp, etc. It is possible to use the lamp and to prompt the exchange of the discharge lamp. Further, the display of the discharge lamp abnormality is not limited to the LED display, and may be voice guidance, for example.

Embodiment 9 FIG.
FIG. 10 is a diagram showing a configuration of a discharge lamp lighting device according to Embodiment 9 of the present invention. In the ninth embodiment, the current flowing through the shunt resistor 11 shown in FIG. 1 of the first embodiment is detected, the detected signal is compared with the target current value, and the switching frequency is controlled so as to approach the target value. The microcomputer 18 comprises an inverter control circuit 12 having a feedback control means and a preheating switch control circuit 16 for controlling on / off of the preheating switch. The operation is the same as that of any one of the discharge lamp lighting devices described in the first to eighth embodiments, and the description thereof is omitted.

  In the ninth embodiment, any one of the preheating current controls described in the first to eighth embodiments is controlled by a microcomputer. Inverter control and preheating current control are performed by software. In comparison, the number of parts can be reduced, and the circuit configuration can be simplified and the cost can be reduced.

  In this way, by controlling the inverter control and the preheating current control with a microcomputer, the circuit configuration can be simplified by reducing the number of parts compared to the conventional hardware control circuit, and the cost can be reduced. .

Embodiment 10 FIG.
In the tenth embodiment, any one of the discharge lamp lighting devices described in the first to ninth embodiments is mounted on the fixture body 19 as shown in FIG. 11 to form a lighting device. That is, the discharge lamp lighting device 21 is housed inside the fixture body 19, and the discharge lamp 20 is mounted on the lamp socket 22 outside the fixture body 19 and connected to the discharge lamp lighting device 21 by the wiring 23 to form a lighting device. .

  According to this lighting device, the filament preheating current is interrupted at the time of all light or in the vicinity of all light, and the preheating current is supplied at the time of dimming, and appropriate discharge lamp power feedback can be performed, thereby achieving energy saving as the entire lighting device. .

It is a block diagram of the discharge lamp lighting device which shows Embodiment 1 of this invention. 3 is a timing chart based on the operation of the discharge lamp lighting device according to Embodiment 1. 6 is a timing chart based on the operation of the discharge lamp lighting device according to Embodiment 2. 10 is a graph showing the relationship between the dimming degree of the discharge lamp lighting device and the preheating current in the third embodiment. It is a figure which shows the preheating current waveform of the discharge lamp lighting device in Embodiment 3. FIG. It is a graph which shows the relationship between the light control degree of the discharge lamp lighting device in Embodiment 4, and a target switching current. It is a figure which shows the preheating current waveform of the discharge lamp lighting device in Embodiment 5. FIG. It is a figure which shows the relationship between the preheating current of the discharge lamp lighting device in Embodiment 6, and a target switching current. 10 is a timing chart based on the operation of the discharge lamp lighting device in the seventh embodiment. It is a block diagram of the discharge lamp lighting device which shows Embodiment 9 of this invention. It is a figure which shows the structure of the illuminating device in Embodiment 10 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Commercial AC power supply, 2 Rectification part, 3 Boost chopper circuit, 4 Smoothing capacitor, 5a, 5b Switch element, 6 Switching element driver, 7 Ballast coil, 8 Discharge lamp, 8a, 8b Filament, 9 Resonance capacitor, 10 DC cut Capacitor, 11 Shunt resistor, 12 Inverter control circuit, 13 Filament preheating transformer, 14 Preheating switch, 15 DC cut capacitor, 16 Preheating switch control circuit, 17 Dimming controller, 18 Microcomputer, 19 Instrument body, 20 Discharge lamp, 21 Release Electric lighting device, 22 lamp socket, 23 wiring.

Claims (11)

A rectifier circuit for rectifying an AC power supply;
A DC power supply circuit that includes a smoothing capacitor and converts the output of the rectifier circuit to a desired DC output;
An inverter circuit that includes a plurality of switching elements, converts the output of the DC power supply circuit to a high frequency by turning on and off the plurality of switching elements, and supplies high frequency power to the discharge lamp;
An inverter control circuit for controlling the on / off operation of the switching element of the inverter circuit;
A filament preheating transformer connected to the output of the inverter circuit for supplying a current for preheating the filament of the discharge lamp;
A preheating switch connected in series with the filament preheating transformer;
A preheating switch control circuit for controlling on / off of the preheating switch;
Switching current detecting means for detecting a current flowing in the switching element of the inverter circuit;
Feedback control means for comparing and calculating the current value detected by the switching current detection means and the target current value determined by the dimming control signal, and variably adjusting the switching frequency of the inverter circuit according to the comparison calculation result. ,
The feedback control means adds a switching current value corresponding to a preheating current supply to the target current value during filament preheating current supply.   The feedback control means disables the feedback control for a predetermined period after the discharge lamp is lit, and causes the preheating switch control circuit to turn on / off the preheating switch one or more times during the predetermined period, 2. The discharge lamp lighting device according to claim 1, wherein a switching current value corresponding to a preheating current supply is obtained by taking a difference between the switching currents detected by the switching current detecting means.   The discharge lamp lighting device according to claim 1, wherein the preheating switch control circuit turns off the preheating switch in an all-light state or a state close thereto.   The preheating switch control circuit controls a duty which is a ratio of an on time and an off time of the preheating switch according to a dimming control signal, and sets an on time ratio of the preheating switch in the all-light state or a state close thereto. 2. The discharge lamp lighting device according to claim 1, wherein the on-time ratio of the preheating switch is set to be longer than the second value in a dimming state with a lower luminous flux than the value.   The feedback control means makes a current value corresponding to a preheating current supply added to a target value of a switching current proportional to an on-time ratio of a preheating switch controlled by the preheating switch control circuit. 5. The discharge lamp lighting device according to 4.   The preheating switch control circuit is characterized in that when the preheating current is cut off, the preheating switch gradually decreases the on-time ratio as time elapses from the on state, and finally the preheating switch is completely turned off. The discharge lamp lighting device according to 1.   The feedback control means preheats a switching current corresponding to a preheating current supply to be added to a switching current target value in a preheating current interruption period in which the ratio of the on-time of the preheating switch is gradually shortened as time elapses. 7. The discharge lamp lighting device according to claim 6, wherein the discharge lamp lighting device is proportional to an on-time ratio of the switch.   The feedback control means turns on or off the preheating switch one or more times by the preheating switch control circuit, and the difference between the switching currents detected by the switching current detecting means in each of the on period and the off period is outside a predetermined range. 3. The discharge lamp lighting device according to claim 2, wherein the inverter operation is stopped.   The feedback control means displays information when the inverter operation is stopped when the difference between the switching currents detected by the switching current detection means is outside a predetermined range in each of the ON period and the OFF period of the preheating switch. 9. The discharge lamp lighting device according to claim 8, wherein the discharge lamp lighting device outputs to a device or the like.   The discharge lamp lighting device according to any one of claims 1 to 9, wherein the feedback control means and the preheating switch control circuit are constituted by a one-chip microcomputer.   An illuminating device comprising: the discharge lamp lighting device according to any one of claims 1 to 10, a fixture main body on which the discharge lamp lighting device is mounted, and a discharge lamp.

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