JP2001351790A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device having superior circuit efficiency and moreover reduced stresses to an inverter circuit. SOLUTION: An inverter control circuit 3 sets the operation frequency of the inverter circuit 2 at preheating mode time in a sufficiently high region relative to resonance frequencies of a resonant inductor L1 and a resonant capacitor C1, so that start of a discharge lamp 1 does not occur. A preheat switching element SW3 in a preheat control circuit 4 is switched to on state, to preheat the discharge lamp 1 by the secondary output of a preheat transformer T2. After the elapse of a fixed time, the operating frequency of the inverter circuit 2 is set in a region, where a voltage required for starting the discharge lamp 1 can be applied, to make the discharge lamp 1 start. Thereafter the operating frequency of the inverter circuit 2 is set, so that the voltage applied on the discharge lamp 1 becomes a voltage for executing rated lighting of the discharge lamp 1, and the preheating switch element SW3 is switched to off state, to make a filament current IF cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device.

[0002]

2. Description of the Related Art FIG. 10 shows a discharge lamp corresponding to a hot cathode type discharge lamp.
This shows a conventional example of an electric light lighting device.
The inverter circuit 2 converts the DC voltage from the DC power supply E
And the high frequency output of the inverter circuit 2 is shared.
The vibration inductor L1, the discharge lamp 1, and both discharge lamps 1
Resonance capacitors connected to the non-power-supply-side ends of the filaments F1 and F2.
The discharge lamp 1 is applied to a load circuit composed of the
Preheating, starting, and lighting, the resonance inductor L1
Using the resonance characteristics of the capacitor C1
As shown in FIG. 11, the operating frequency of the
Resonance frequency between inductor L1 and resonance capacitor C1
f0 (f0 = 1 / [2π · (L1 · C1) ^1/2])Than
By setting to high f1, the discharge lamp 1
Reduce the lighting voltage and perform preheating in a state where the discharge lamp 1 does not start.
After that, the operating frequency of the inverter circuit 2 approaches f0.
By increasing the voltage applied to the discharge lamp 1,
It is designed to light up dynamically.

In this conventional example, even after the discharge lamp 1 is turned on, the filament current continues to flow through the filaments F1 and F2 of the discharge lamp 1 via the resonance capacitor C1, so that the power loss in the filaments F1 and F2 during the turn-on operation. And the circuit efficiency as a discharge lamp lighting device cannot be increased,
As a result, there is a problem that the contribution to energy saving is low.

As another conventional example, as shown in FIG. 12, a secondary winding connected in series to a winding of a resonance inductor L1 is provided, and this secondary winding is connected to a filament F of a discharge lamp 1.
1, a pre-heating switch element SW between the non-power supply side ends of F2
And turns on the pre-heating switch element SW1 for a certain period of time under the control of the control circuit 3 after the power is turned on. During this ON period, the filaments F1 and F2 of the discharge lamp 1 are turned on.
Then, the filament current is caused to flow by the output of the secondary winding to perform preheating, and after a lapse of a predetermined time, the control circuit 3 controls the preheating switch element SW1 to be turned off, and the high voltage from the inverter circuit 2 is released. Apply to both ends of the light 1,
Some start and turn on the discharge lamp 1.

[0005] As shown in FIG.
Is applied to both ends of the discharge lamp 1 via the leakage transformer T1 and the DC power supply E is connected to the DC power supply E via the preceding preheating switch element SW2, the resistor R1 and the inductor L2. 1 is connected between the non-power-supply-side ends of the filaments F1 and F2, and when the power is turned on, the preheating switch element SW2, the resistor R1, the inductor L2, the filament F1, the secondary winding of the leakage transformer T1, the filament F
The preheating is performed by passing a DC filament current to the filaments F1 and F2 through the loop 2, and when the preheating is completed after a lapse of a predetermined time, the preheating switch element SW2 is turned off to cut off the filament current and simultaneously operate the inverter circuit 2. A discharge lamp lighting device for starting and lighting the discharge lamp 1 with the high-frequency output has been conventionally provided.

[0006]

FIG. 12 and FIG. 13 described above.
The conventional example shown in FIG. 1 is characterized in that the power consumption of the filaments F1 and F2 of the discharge lamp 1 at the time of lighting is eliminated, and the circuit efficiency as a discharge lamp lighting device is improved as compared with the conventional example shown in FIG.

However, in the prior art shown in FIGS. 12 and 13, the filaments F1 and F2 are preheated and the thermoelectrons are sufficiently emitted from the filaments F1 and F2 when the preheating switch element SW1 or SW2 is on. Even if the temperature of the filaments F1 and F2 rises, the discharge lamp 1
After the preheating of the filaments F1 and F2 is turned off, the high voltage output from the inverter circuit 2 is applied to both ends of the discharge lamp 1 to start the discharge lamp 1, so that the switch elements SW1 and SW2 are turned off. Due to the time lag from the start until the starting voltage is applied to the discharge lamp 1, the filament F
1, there is a problem that the temperature of F2 is lowered. Therefore, in order to secure the startability at a low temperature, it is necessary to increase the voltage required for the start or prolong the time for applying the start voltage. As a result, there is a problem that stress on circuit components such as an inverter circuit, a transformer, an inductor, and a capacitor increases, and the device becomes larger.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a discharge lamp lighting device which is excellent in circuit efficiency and reduces stress on an inverter circuit. is there.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, there is provided an inverter circuit for lighting a hot cathode type discharge lamp at a high frequency, and a method for preheating, starting and lighting the discharge lamp. An inverter control circuit that controls the operation of the inverter circuit so as to exhibit a stage operation state, and preheats by supplying a filament current to the filament of the discharge lamp when the inverter circuit is in a preheating / starting operation state;
And a preheating control circuit for setting so as to suppress a filament current flowing through the filament of the discharge lamp in a lighting operation state.

According to a second aspect of the present invention, there is provided an inverter circuit for lighting a hot cathode type discharge lamp at a high frequency, a rectifier circuit for rectifying a commercial power supply and flowing a rectified output to the inverter circuit,
An input current waveform improving means for controlling an input current flowing from the rectifier circuit to the inverter circuit using a high-frequency voltage alternating in synchronization with the operation of the inverter circuit; and a preheating, starting and lighting stage of the discharge lamp. An inverter control circuit for controlling the operation of the inverter circuit so as to exhibit an operation state, and when the inverter circuit is in a preheating / starting operation state, a filament current is supplied to a filament of the discharge lamp to preheat and light. And a preheating control circuit for setting so as to suppress a filament current flowing through the filament of the discharge lamp in the operation state of (1).

According to a third aspect of the present invention, in the second aspect of the present invention, a step-down chopper choke, a smoothing capacitor, and the smoothing capacitor are provided between both ends of a series circuit of a pair of switching elements constituting the inverter circuit. And a series circuit with the first diode in a direction in which the first capacitor is discharged, and a smoothing capacitor is charged between a connection midpoint between the smoothing capacitor and the first diode and a connection midpoint between the pair of switching elements. A step-down chopper having a second diode, and an impedance circuit which is inserted between the output terminal of the rectifier circuit and the inverter circuit and is at least a parallel circuit of a third diode and a capacitor. The input power factor waveform improving means is constituted.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the preheating control circuit applies a high-frequency voltage of the inverter circuit to both ends as a power supply.
It consists of a series circuit of a capacitor, a primary winding of a transformer element for preheating, and a switch element for preheating. The preheating switch element is turned on during a preheating / start operation state, and the preheating provided in the transformer element for preheating. It is characterized in that a filament current is passed from the application winding to the filament of the discharge lamp.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the preheating switch element is constituted by a MOSFET.

According to a sixth aspect of the present invention, in the fourth or sixth aspect, the preheating switch element is constituted by a parallel circuit of a bidirectional switch element and a capacitor.

According to a seventh aspect of the present invention, in the fourth aspect of the present invention, the preheating transformer element is constituted by a combination of an inductor and a current transformer.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the hot cathode discharge lamp is a discharge lamp dedicated to a high frequency.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. (Embodiment 1) As shown in FIG. 1, a discharge lamp lighting device according to this embodiment includes an inverter circuit 2 for converting a DC from a DC power supply (including a power supply obtained by rectifying and smoothing a commercial power supply) E into a high frequency.
A resonance inductor L1 connected between the output terminals of the inverter circuit 2, a hot-cathode discharge lamp 1 connected in series to the resonance inductor L1, and a resonance connected in parallel to the discharge lamp L1. Control comprising a load circuit comprising a capacitor C1 and a series circuit of a capacitor C2, a transformer T2 for preheating, and a switch element SW3 for preheating as a preheating switch element between output terminals of the inverter circuit 2 like the load circuit. A circuit 4 and an inverter control circuit 3 for controlling ON / OFF of the switch element SW3 and for controlling the operation of the inverter circuit 2. Two preheating windings N21 provided in a transformer T2 as a preheating transformer element. , N22 through the capacitors C4 and C5, the filament F1 of the discharge lamp 1,
Connected to F2.

Next, the operation of this embodiment will be described with reference to the timing chart shown in FIG.

When power is turned on and operation starts,
First, the inverter control circuit 3 operates as shown in FIGS. 2 (a) and 2 (b).
The control signals A and B are output. The two types of control signals A and B are used to preheat the inverter circuit 2 by combination.
A control signal for setting each operation state of starting and lighting is configured. Further, control for turning on or off the switch element SW3 is performed in accordance with this operation state.

When both the control signals A and B are "H", the preheating operation state (preheating mode) is set as shown in FIG. On the other hand, as shown in FIG. 2G, the switch element SW3 is turned on. In this preheating mode, the operating frequency of the inverter circuit 2 is set in a region sufficiently higher than the resonance frequency f0 of the resonance inductor L1 and the resonance capacitor C1 (see FIG. 11), and is applied to the discharge lamp 1 from the inverter circuit 2. The voltage Vla is set to a value sufficiently lower than the voltage required for starting, as shown in FIG. 2C, so that the discharge lamp 1 is not started. On the other hand, transformer T2 for preheating
, A current flows by the high-frequency output of the inverter circuit 2 through the capacitor C2 and the bidirectional preheating switch element SW3, which is a preheating switch element, so that the preheating coil of the preheating transformer T2. The filament current IF flows from the lines N21 and N22 to the filaments F1 and F2 of the discharge lamp 1 through the filament current limiting capacitors C4 and C5 as shown in FIG.

Next, when a certain time has elapsed, the inverter control circuit 3 changes the control signal A to "L". This control signal A
Becomes "L", the operation state of the inverter circuit 2 is changed as shown in FIG.
As shown in (f), a starting operation state (starting mode) is set, and the operating frequency is set in a region where a voltage required to start the discharge lamp 1 can be applied. As shown in FIG. 2 (c), a high voltage Vla is applied, and the discharge lamp 1 starts quickly. As a result, the lamp current Ila flows through the discharge lamp 1 as shown in FIG.

In this starting operation state (starting mode), since the control signal B is "H", in response to this "H", the preheating switch element SW3 is kept on and the discharge lamp 1 is turned on.
The filament current IF continuously flows through the filaments F1 and F2. That is, the discharge lamp 1 has the filaments F1.
F2 will start while being preheated.

After a certain period of time has passed, FIG.
(A) As shown in (b), the inverter control circuit 3 sets the control signals A and B to "L". As a result, the operation state of the inverter circuit 2 becomes a lighting operation state (lighting mode) as shown in FIG. 2 (f), and the operating frequency is changed so that the voltage applied to the discharge lamp 1 becomes the voltage for rated lighting of the discharge lamp 1. Is set. Further, in response to the control signal B becoming "L", the preheating switch element SW3 of the preheating control circuit 4 is turned off, and by this turning off, the preheating winding N2 of the preheating transformer T2.
1 and N22, the filament current IF flowing to the filaments F1 and F2 of the discharge lamp 1 is cut off.

The voltage Vla shown by a broken line in FIG.
Indicates a voltage when the discharge lamp 1 is not turned on.

As described above, in the present embodiment, when the discharge lamp 1 shifts to the rated lighting, the filament current IF is cut off, so that it is possible to provide a discharge lamp lighting device with low power loss and high circuit efficiency. .

Further, according to the present embodiment, the filaments F1 and F2 are preheated even during the start mode of the discharge lamp 1, so that an unnecessary start voltage as described in the prior art is applied to the discharge lamp 1. It is not necessary to perform the operation, and it is possible to start at a relatively low voltage or in a short period of time even in a low-temperature environment, thereby reducing stress on the inverter circuit 1 and providing a highly reliable and highly efficient discharge lamp lighting device. It becomes possible.

The inverter circuit 2 of this embodiment can be a half-bridge type, a full-bridge type, a push-pull type, or a single-type inverter circuit, and the circuit type is not particularly limited.

(Embodiment 2) In this embodiment, as shown in FIG. 3, a capacitor C6 is connected to an output terminal of a rectifier circuit DB for full-wave rectification of a commercial power supply AC, and an inverter circuit 2 is connected in parallel with the capacitor C6. A series circuit of switching elements Q1 and Q2 composed of MOSFETs is connected to a diode D
3, D4, and both switching elements Q1, Q
2 and the connection point of the diodes D3 and D4,
That is, a series circuit of a DC cut capacitor C7 and the primary winding of the leakage transformer T3 is connected to the output terminal of the inverter circuit 2, and a DC cut capacitor C8 is connected to the secondary winding of the leakage transformer T3. And a resonance capacitor C1 that forms a resonance circuit with the inductance of the leakage transformer T3
And the discharge lamp 1 are connected, and the discharge lamp 1, the capacitors C8 and C1, and the leakage transformer T3 constitute a load circuit. The capacitor C9 connected in parallel with the diode D3 is a capacitor for improving the power factor.
The diodes D3 and D4 form an impedance element.

On the other hand, a diode D is connected in parallel with a series circuit of a DC cut capacitor C7 and a primary winding of a leakage transformer T3.
3, a preheating control circuit 4 composed of a series circuit of a capacitor C2, a primary winding of a preheating transformer T2, and a preheating switch element SW3 is connected to the preheating transformer T2 as in the first embodiment. The preheating coils N21 and N22 are connected to the filaments F1 and F1 of the discharge lamp 1 via capacitors C4 and C5, respectively.
Connected to F2.

A capacitor C10 is connected in parallel to a series circuit of the switching elements Q1 and Q2, and a series circuit of a step-down chopper inductor L3, a smoothing capacitor C3, and a diode D2 in a direction opposite to the power supply is connected in parallel. The diode D1 is connected between the connection point of the two switching elements Q1 and Q2 and the connection point of the smoothing capacitor C3 and the diode D2.

The step-down inductor L3, the smoothing capacitor C3, and the diodes D2 and D1 constitute a step-down chopper circuit, and the above-mentioned impedance element constitutes an input current waveform improving means.

The inverter control circuit 3 switches the switching elements Q1 and Q of the inverter circuit 2 in accordance with the preheating, starting and rated lighting operation states of the discharge lamp 1 as in the first embodiment.
2 and a bidirectional preheating switch element SW3 in each of the preheating and starting operation states.
Is turned on, and turned off in the rated lighting operation state.

Next, the operation of this embodiment will be described.

First, when power is turned on, the inverter control circuit 3 turns on the preheating switch element SW3,
The driving frequency of the switching elements Q1 and Q2 is set to a frequency sufficiently higher than the resonance frequency f0 of the resonance capacitor C1 and the inductor of the leakage transformer T3 so that the voltage applied to the discharge lamp 1 is equal to or lower than the starting voltage. .

Therefore, the filaments F1, F2 of the discharge lamp 1
The filament current IF flows from the preheating windings N21 and N22 of the preheating transformer T2 via the capacitors C4 and C5, and is preheated.

The voltage generated across the resonance capacitor C1, that is, the lamp voltage Vla is lower than the starting voltage, so that the discharge lamp 1 does not start.

Next, after a lapse of a predetermined time, the inverter control circuit 3 drives the switching elements Q1 and Q2 of the inverter circuit 2 so that a high voltage capable of starting the discharge lamp 1 is generated across the resonance capacitor C1. Set the frequency and shift to the starting operation state. As a result, the discharge lamp 1 is started. Even during this start-up operation state, the preheating switch element SW3 is kept on to keep the preheating.

When a certain period of time has elapsed, the inverter control circuit 3 turns off the preheating switch element SW3 to cut off the filament current IF, and at the same time, the discharge lamp 1
Sets the drive frequency of the switching elements Q1 and Q2 in the rated lighting state, and shifts the inverter circuit 2 to the rated lighting operation state.

According to the series of operations described above, the filaments F1 and F2 are also preheated during the start mode of the discharge lamp 1 as in the first embodiment. , A relatively low voltage or a short-period oscillation is possible even in a low-temperature environment, so that stress on the inverter circuit 1 can be reduced, and a highly reliable and highly efficient discharge lamp lighting device can be provided. Can be provided.

Here, in the input current waveform distortion improving means used in the present embodiment, the switching element Q2 of the inverter circuit 2 is used as both the switching element for the inverter and the switching element for the chopper, and the input voltage of the inverter circuit 2 and the capacitor When the input voltage is higher than the charging voltage of C3, the capacitor C3 is charged by the step-down chopper operation, and the input current to the inverter circuit 2 flows continuously. If it is larger, the electric charge of the capacitor C3 is discharged to the inverter circuit 1. And the capacitor C of the impedance element
The input current continues to be supplied to the inverter circuit 2 by the charge pump operation by the charging and discharging of No. 9 to improve the input current waveform.

When the input current waveform distortion improving means exists, the voltage applied to the switching elements Q1 and Q2 of the inverter circuit 2 rises when the discharge lamp 1 is not loaded before starting (light load). Therefore, in the conventional method of applying a high voltage to the discharge lamp after the interruption of the filament current, a high voltage is applied to the switching element, so that it is necessary to use a switching element having a large withstand voltage. In the start mode, the filament current I
Since F flows, the voltage applied at the time of starting can be set low. As described above, the voltage applied to the switching elements Q1 and Q2 of the inverter circuit 2 increases when there is no load (light load). Even so, a switching element having a relatively low withstand voltage can be selected, and the size of the device can be reduced. (Embodiment 3) One of the preheating transformers T2 of Embodiments 1 and 2
The preheating switch element SW3 connected in series with the next winding may be a switch element such as a bidirectional semiconductor switch element or a relay contact. In this embodiment, as shown in FIG. 4 is characterized in that a MOSFET _Q3 having a parasitic diode DQ3 is used as a preheating switch element.

Since other configurations are the same as those of the second embodiment, reference is made to FIG. 3 and illustration and description are omitted here.

In this embodiment, in the preheating and starting operation state (preheating / starting mode), the inverter control circuit 3 supplies the MOSFET Q3 as a preheating switch element to the MOSFET Q3 shown in FIG.
The gate drive signal shown in FIG. In this case, due to the parasitic diode DQ3 of the MOSFET _Q3 , a bidirectional current flows as a switch element, and thus a high-frequency AC current _IT2 shown in FIG. 5B flows through the primary winding of the preheating transformer T2. At this time the capacitor C2 acts mainly as a DC blocking capacitor, the both ends positive DC voltage as shown in FIG. 5 (c) are generated as Vc _3.

At the time of transition to the rated lighting state (lighting mode), the gate drive signal from the inverter control circuit 3 disappears, so that the MOSFET Q3 is turned off. However, since the parasitic diode D _Q3 exists, the switching elements Q1, Q
A part of the current from the inverter circuit 2 composed of
As shown in FIG. 5B, the current flows through the parasitic diode D _Q3 to the capacitor C2 to reversely charge the capacitor C2 as shown in FIG. 5C, and the voltage V _{C2 is set} to a negative voltage. When the voltage V _C2 is charged to a certain constant voltage, reverse charging of the capacitor C2 substantially disappears, and at that time, the current flowing through the preheating transformer T2 substantially disappears, and the filament current IF is cut off. Becomes

As described above, according to the present embodiment, the preheating is turned on and off by utilizing the characteristics of the capacitor C2 for cutting off DC, that is, utilizing the fact that the DC charging to the capacitor C2 is stopped when the voltage reaches a predetermined voltage. Can be configured only with the MOSFET Q3 as a preheating switch element, and as a result, the preheating control circuit 4 can be configured with a simple and inexpensive circuit. (Fourth Embodiment) In the third embodiment, the preheating switch element of the preheating control circuit 4 is a MOS transistor including a parasitic diode DQ3.
Although the FET Q3 is used, in the present embodiment, FIG.
As shown in (1), a switch element SW3 formed by a bidirectional semiconductor switch element or a relay contact is used, and a capacitor C12 is connected in parallel to the switch element SW3.

Other configurations are the same as those of the first or second embodiment shown in FIG.
Alternatively, since the circuit configuration shown in FIG. 3 may be used, these are referred to, and illustration and description are omitted here.

Thus, even if the switch element SW3 is turned off in the rated lighting operation state under the control of the inverter control circuit 3, that is, in the lighting mode, the series circuit of the capacitor C2, the preheating transformer T2, and the capacitor C12. Current will continue to flow through the primary winding of the preheating transformer T2. At this time, the filament current IF is the primary side capacitor C
Twelve capacities can be set freely. For example, when lighting the discharge lamp 1 in the dimming state, the filament temperature decreases due to the decrease in the lamp current Ila, and the filaments F1, F1
There is a problem that the stress on the lamp 2 increases and the life of the lamp is shortened. However, in order to prevent the problem, it is effective to use the present embodiment when the filament current IF always flows for the purpose of keeping the filament temperature during lighting appropriate. It is.

As described above, also in the present embodiment, by appropriately selecting the value of the capacitor C12, unnecessary power consumption in the filaments F1 and F2 can be suppressed, so that an improvement in circuit efficiency can be expected. It is.

(Embodiment 5) In this embodiment, as shown in FIG. 7, a lighting detection circuit 5 is added to the configuration of Embodiment 1 shown in FIG.

That is, in the first embodiment, the switch element SW3 of the preheating control circuit 4 is turned on during each of the preheating and starting modes, and the filament current IF is continuously supplied. When the discharge lamp 1 is turned on in the start mode, the lighting detection circuit 5 detects the lighting and sends a detection signal to the inverter control circuit 3, and the inverter control circuit 3 receiving the detection signal is in the start mode period. Also, the switch element SW3 is turned off to stop the preheating. Here, the lighting detection of the lighting detection circuit 5 is performed by detecting that the lamp voltage Vla of the discharge lamp 1 changes before and after starting. Of course, the lamp current Ila may be monitored to detect that the lamp current Ila has flowed.

The other operations are the same as those of the first embodiment, and the description is omitted.

According to the present embodiment, unnecessary power can be reduced more quickly. (Embodiment 6) In the preheating control circuit 4 of the above-mentioned Embodiments 1 to 5, the transformer T2 is used as a transformer element for preheating, and the discharge lamp 1
Although the filament current IF is caused to flow through the filaments F1 and F2 of this embodiment, in the present embodiment, as shown in FIG. 8, two preheating current transformers CT1 and CT2 are used, and these preheating current transformers CT1 and CT2 are used. The filament current IF is obtained by the secondary output of CT2, and the preheating control circuit 4 of the present embodiment includes a capacitor C2, as shown in FIG.
A series circuit of an inductor L4, a primary winding of a current transformer CT1, a primary winding of a current transformer CT2, and a parallel circuit of a preheating switch element SW3 and a capacitor C12;
As the inverter circuit 12, for example, a circuit as in the second embodiment is used, where the capacitor C2 forms a DC cut capacitor.

In this embodiment, the switching element SW
In a lighting mode in which the inverter 3 is turned off by the inverter control circuit 3, a series resonance circuit is formed by the inductor L4 and the capacitor C12, and the series impedance of the inductor L4 and the capacitor C13 changes according to the operating frequency of the inverter circuit 2. Thus, the magnitude of the filament current IF can be set appropriately.

Also, in the preheating mode, since the preheating switch element SW3 is on, the magnitude of the filament current IF is determined by the inductance value of the inductor L4.

FIG. 9 shows the relationship between the operating frequency of the inverter circuit 2 and the current flowing through the inductor L4.
F is the rated lighting frequency, and f01 is the inductor L4
And the resonance frequency of the capacitor C12 (= 1 / [2π (L4
· C12) ^1/2 ]).

In the present embodiment using the preheating control circuit 4 having the above-described configuration, in the case of a discharge lamp lighting device for controlling the discharge lamp 1 to a low luminous flux region as in continuous dimming, for example, the operation of the inverter circuit 2 As the frequency is increased and the lamp current Ila is continuously reduced, the filament current IF can be increased, and the spot temperature of the filaments F1 and F2 can always be kept at an appropriate level. The lamp life can be ensured, and the filament current IF at the time of rated lighting can be suppressed as in the above-described first to fifth embodiments, and an improvement in circuit efficiency can be expected.

Note that fD in FIG. 9 indicates the frequency at the lower limit of dimming. (Embodiment 7) By the way, the discharge lamp 1 used in the discharge lamp lighting devices of the above embodiments 1 to 6 is a hot cathode type discharge lamp 1
Although there is no particular limitation on the type, further energy saving can be achieved by combining a hot cathode fluorescent lamp (hereinafter referred to as an Hf lamp) dedicated to high-frequency lighting.

In other words, Hf lamps having lamp lengths of 2 feet, 4 feet, and 5 feet have already been developed according to their applications. Compared to a 40W-series straight tube fluorescent lamp, the tube diameter is smaller and the efficiency of the lamp itself is excellent, and it is a lamp that has recently been in the limelight from the viewpoint of reducing the thickness of lighting equipment and saving energy. By using such an Hf lamp, the efficiency as a discharge lamp lighting device can be increased, and a further energy saving effect can be expected as compared with a discharge lamp lighting device in which a conventional lamp is turned on at high frequency using an inverter circuit.

However, as described above, as the lighting equipment becomes thinner, the discharge lamp lighting device is made thinner and smaller, and even if the efficiency of the discharge lamp lighting device is improved, the miniaturization makes it possible to reduce the operating temperature environment. Was tough.

Therefore, the present embodiment is characterized in that the Hf lamp is combined with any of the discharge lamp lighting devices of the first to sixth embodiments, so that the power loss during lighting is reduced.
A conventional discharge lamp lighting device simply using an inverter circuit and H
As compared with the combination with the f-lamp, the operation efficiency of the discharge lamp lighting device itself can be reduced with higher efficiency, and higher reliability can be ensured.

The circuit configuration of the discharge lamp lighting device using the inverter circuit 2, the preheating control circuit 4 and the like is described in Embodiment 1.
Since the circuit configuration of any one of the above-described configurations may be adopted, the illustration and the description are omitted here.

[0062]

According to the first aspect of the present invention, there is provided an inverter circuit for lighting a hot-cathode discharge lamp at a high frequency, and an inverter circuit for operating the discharge lamp at each stage of preheating, starting and lighting. An inverter control circuit for controlling the operation; a filament current is supplied to the filament of the discharge lamp when the inverter circuit is in a preheating / starting operation state to preheat the filament; Since a preheating control circuit is set to suppress the filament current, it is possible to suppress the filament power consumption in the operating state of lighting, thereby improving the circuit efficiency, and preheating the filament even in the starting operation state. Therefore, it is not necessary to apply an unnecessarily high starting voltage to the discharge lamp. Enables starting of the period, it is possible to reduce the stress results inverter circuit, high reliability,
There is an effect that a highly efficient discharge lamp lighting device can be provided.

According to a second aspect of the present invention, there is provided an inverter circuit for lighting a hot-cathode discharge lamp at a high frequency, a rectifier circuit for rectifying a commercial power supply to supply a rectified output to the inverter circuit, and synchronizing with the operation of the inverter circuit. An input current waveform improving means for controlling an input current flowing from the rectifier circuit to the inverter circuit by using an alternating high frequency voltage, and an operating state of each stage of preheating, starting and lighting of the discharge lamp. An inverter control circuit for controlling the operation of the inverter circuit, and when the inverter circuit is in a preheating / starting operation state, the filament current of the discharge lamp is preheated by flowing a filament current to the discharge lamp filament. A preheating control circuit is set to suppress the filament current flowing through the filament of the discharge lamp, so that the input current waveform can be improved. In addition, the power consumption of the filament in the operating state of lighting can be suppressed to improve the circuit efficiency, and the filament is preheated even in the starting operation state, so that an unnecessarily high starting voltage is applied to the discharge lamp. There is no necessity, and therefore, it is possible to start at a relatively low voltage or a short period even in a low-temperature environment. As a result, the stress of the inverter circuit can be reduced. Therefore, the voltage applied to the inverter circuit at the time of light load, which tends to increase due to the provision of the input power factor improving means, can be reduced to a low voltage. As a result, as a switching element of the inverter circuit, There is an effect that a material having a relatively low withstand voltage can be used.

According to a third aspect of the present invention, in the second aspect of the present invention, a step-down chopper choke, a smoothing capacitor, and the smoothing capacitor are provided between both ends of a series circuit of a pair of switching elements constituting the inverter circuit. And a series circuit with the first diode in a direction in which the first capacitor is discharged, and a smoothing capacitor is charged between a connection midpoint between the smoothing capacitor and the first diode and a connection midpoint between the pair of switching elements. A step-down chopper having a second diode, and an impedance circuit which is inserted between the output terminal of the rectifier circuit and the inverter circuit and is at least a parallel circuit of a third diode and a capacitor. By configuring the input waveform improving means, it is possible to realize a discharge lamp lighting device exhibiting the effect of the second aspect of the present invention.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the preheating control circuit includes a capacitor and a preheating transformer element to which a high-frequency voltage of the inverter circuit is applied as a power source at both ends. The primary winding and the preheating switch element are connected in series, and the preheating switch element is turned on during the preheating / starting operation state, and the discharge lamp is connected to the preheating transformer element through the preheating winding provided in the preheating transformer element. Since a filament current flows through the filament, a preheating control circuit can be realized with a simple circuit configuration.

In particular, the invention of claim 5 is the invention of claim 4, wherein the preheating switch element is constituted by a MOSFET, and the preheating switch element can be constituted only by a MOSFET by utilizing a charging characteristic of a capacitor. Therefore, a preheating control circuit can be realized simply and at low cost.

According to a sixth aspect of the present invention, in the fourth aspect, the preheating switch element is constituted by a parallel circuit of a bidirectional switch element and a capacitor. The current value can be set by the value of the capacitor connected in parallel with the element, so that the flow of the filament current more than necessary can be suppressed and the circuit efficiency can be improved.

According to a seventh aspect of the present invention, in the fourth or sixth aspect of the present invention, the preheating transformer element is constituted by a combination of an inductor and a current transformer, thereby achieving the effect of the fourth aspect of the present invention. A lamp lighting device can be realized, and in particular, the value of the current flowing in the starting operation state and the lighting state at the operating frequency of the inverter circuit can be appropriately set by the capacitor connected to the switch element and the resonance circuit with the inductor.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, since the hot cathode discharge lamp is a high frequency discharge lamp, the energy saving characteristic of the high frequency discharge lamp is improved. The synergistic effect with the improvement of the circuit efficiency by the suppression of the filament current in the lighting operation state reduces the power loss at the time of lighting, thereby achieving higher efficiency, and as a result, the calorific value of the lighting device itself is reduced, and the resulting device is reduced. Operating temperature can be reduced, and higher reliability can be ensured.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining the above operation.

FIG. 3 is a circuit configuration diagram according to a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram of a main part according to a third embodiment of the present invention.

FIG. 5 is a timing chart for explaining the above operation.

FIG. 6 is a circuit configuration diagram of a main part according to a fourth embodiment of the present invention.

FIG. 7 is a circuit configuration diagram according to a fifth embodiment of the present invention.

FIG. 8 is a circuit configuration diagram of a main part according to a sixth embodiment of the present invention.

FIG. 9 is an operation explanatory view of the above.

FIG. 10 is a circuit configuration diagram of a conventional example.

FIG. 11 is an operation explanatory diagram of the above.

FIG. 12 is a circuit configuration diagram of another conventional example.

FIG. 13 is a circuit configuration diagram of another conventional example.

[Explanation of symbols]

 E DC power supply 1 Discharge lamp 2 Inverter circuit 3 Inverter control circuit 4 Preheating control circuit SW3 Switch element T2 Preheating transformer C2 Capacitor F1, F2 Filament L1 Resonance inductor C1 Resonance capacitor C4, C5 Capacitor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Asano 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Inventor Kiyoshi Ogasawara 1048 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Works F Terms (reference) 3K072 AA02 BA03 BA05 BC01 BC02 DB01 DC08 DD04 DE06 EB01 GA03 GB01 GB12 GC04 HA05 HB06

Claims (8)

[Claims] An inverter circuit for lighting a hot cathode type discharge lamp at a high frequency, and an inverter control circuit for controlling the operation of the inverter circuit so as to exhibit an operation state of each stage of preheating, starting and lighting of the discharge lamp. When the inverter circuit is in a preheating / starting operation state, a filament current is supplied to a filament of the discharge lamp to perform preheating, and a filament current flowing in the discharge lamp filament is suppressed when the inverter circuit is in a lighting operation state. A discharge lamp lighting device comprising a preheating control circuit for setting. 2. An inverter circuit for lighting a hot-cathode discharge lamp at a high frequency, a rectifier circuit for rectifying a commercial power supply and supplying a rectified output to the inverter circuit, and a high frequency alternating with the operation of the inverter circuit. An input current waveform improving means for controlling an input current flowing from the rectifier circuit to the inverter circuit using a voltage, and an operation of the inverter circuit so as to exhibit an operation state of each stage of preheating, starting, and lighting of the discharge lamp. And an inverter control circuit for controlling
When the inverter circuit is in a preheating / starting operation state, a filament current is supplied to a filament of the discharge lamp to preheat the filament circuit, and when the inverter circuit is in a lighting operation state, the filament current flowing to the discharge lamp filament is set to be suppressed. A discharge lamp lighting device comprising a preheating control circuit. 3. A series connection of a step-down chopper choke, a smoothing capacitor, and a first diode in a direction of discharging the smoothing capacitor between both ends of a series circuit of a pair of switching elements constituting the inverter circuit. Step-down chopper means comprising a circuit and a second diode for charging the smoothing capacitor between a connection midpoint between the smoothing capacitor and the first diode and a connection midpoint between the pair of switching elements. And an impedance circuit, which is inserted between the output terminal of the rectifier circuit and the inverter circuit and is at least composed of a parallel circuit of a third diode and a capacitor, comprising: the input power factor waveform improving means. The discharge lamp lighting device according to claim 2, characterized in that: 4. The preheating control circuit comprises a series circuit of a capacitor, a primary winding of a preheating transformer element, and a preheating switch element, to both ends of which a high-frequency voltage of the inverter circuit is applied as a power supply. The preheating switch element is turned on in a starting operation state, and a filament current flows from the preheating winding provided in the preheating transformer element to the filament of the discharge lamp. The discharge lamp lighting device according to any one of the above. 5. The discharge lamp lighting device according to claim 4, wherein said preheating switch element is constituted by a MOSFET. 6. The discharge lamp lighting device according to claim 4, wherein said preheating switch element is constituted by a parallel circuit of a bidirectional switch element and a capacitor. 7. The preheating transformer element comprises a combination of an inductor and a current transformer.
Or the discharge lamp lighting device according to 6. 8. The discharge lamp lighting device according to claim 1, wherein said hot cathode discharge lamp is a discharge lamp dedicated to high frequency.