JP3438129B2 - Discharge lamp lighting device - Google Patents

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 that performs light processing, and more particularly to a discharge lamp lighting device that can properly perform a startup operation.

[0002]

2. Description of the Related Art Generally, a DC discharge lamp used when performing an optical treatment such as forming an electronic circuit on a semiconductor or forming an electronic circuit on a printed circuit board operates from lighting to stabilizing. Various lighting devices have been proposed.

When the discharge lamp is started, it causes a dielectric breakdown of the enclosed gas, reaches an arc discharge through a glow discharge, and stabilizes the arc discharge, whereby a stable lighting operation of the discharge lamp is performed. Is what you can do. The state of voltage and current from the dielectric breakdown of the discharge lamp to the continuation of the arc discharge is shown by the curve in FIG. 4 (a).

As shown by the arrow (see curve a) in FIG. 4A, the enclosed gas such as mercury and xenon enclosed in the discharge lamp is ionized by applying a high voltage to the electrodes of the discharge lamp. It becomes a conductive gas (dielectric breakdown). Furthermore, when a voltage of several hundred volts is continuously applied to the electrodes of the discharge lamp, the ionization action is further repeated due to the collision of electrons and atoms in the ionized conductive gas, and the discharge continues (arrow)). The electrons involved in the ionization phenomenon at this time are emitted from atoms as a result of ionization of gas. The state in which this discharge continues is called glow discharge, the inter-electrode voltage is about 90 to 120 V, and the current is several hundred mA or less.

Further, when the current is continuously supplied to the gas from the glow discharge state to increase the current, the electrode is heated by the electron collision, the number of thermionic emission from the electrode is increased, and further the ionization action of the enclosed gas is accelerated to increase the current. Becomes easy to flow. This state is called arc discharge (arrow), and the voltage between the electrodes is 20 V to 60 V, and a current of several A to several hundred A easily flows.

[0006] As one of the configurations of the discharge lamp lighting device, there is one that uses a transformer called a leakage transformer that is capable of limiting the current when a load is short-circuited. It is also known that a switch mode lighting device utilizing a semiconductor element is used. Further, there are those that use an activator for dielectric breakdown of the enclosed gas of the discharge lamp to cause glow discharge and arc discharge.

The discharge lamp starter is a DC high voltage generating circuit, and is often used in a discharge lamp called a short arc type having a distance between electrodes of several millimeters. Based on the operating principle of the discharge lamp, It is known that an activator is arranged and arranged to be connected in parallel with a discharge lamp. The starter has a structure in which a diode is connected between the main power supply circuit and the discharge lamp so that a high voltage does not flow into the DC main power supply circuit for maintaining arc discharge.

Further, the discharge lamp starter generates a high voltage of 1000 V or more necessary for dielectric breakdown of the enclosed gas, and
If the main power supply for the discharge lamp can supply the voltage and current required to maintain the arc discharge as shown by the curve d in FIG. 4A, as long as it can supply the current enough to start the arc discharge. good. For that purpose, the output current-voltage characteristic of the starter must be as shown by the dotted line b in FIG.

However, since the starter generates a high voltage and uses a transformer having a large step-up ratio, it can supply only a small current. Therefore, generally, the characteristics are as shown by the chain double-dashed line c in FIG. 4A, and the dielectric breakdown of the enclosed gas can occur, but the glow discharge state can be maintained and further arc discharge cannot be performed. In order to solve this point, increase the capacity of the smoothing capacitor for rectification to generate a high voltage in the starter, and when glow discharge after insulation breakdown starts, the charge accumulated in the capacitor is momentarily stored in the discharge lamp. It is configured so that it is caused to flow, and a large current at this time causes a transition to an arc discharge state.

Even if the above-mentioned measures are taken, when the discharge lamp causes a dielectric breakdown at a relatively low voltage of about 500V, the voltage charged in the smoothing capacitor is 500V. The amount of charge that can be supplied is 1000
Compared with the case of dielectric breakdown with V, the energy is 1/4, which is small. Therefore, if the discharge lamp causes a dielectric breakdown at a low voltage, it becomes impossible to shift to arc discharge. As a countermeasure, the voltage of the smoothing capacitor is 1000V.
It has also been proposed to connect a switching element such as an arrester that is connected to the discharge lamp only when the voltage reaches a predetermined high voltage between the smoothing capacitor and the discharge lamp. This is a circuit configuration well known as a relaxation oscillation circuit to be used.

[0011]

However, the conventional discharge lamp lighting device has the following problems. When using a relaxation oscillator circuit, the switching element is selected so that it conducts only at a high voltage and the energy of the smoothing capacitor is instantaneously supplied to the discharge lamp. The voltage change becomes much more abrupt than that of a normal relaxation oscillation circuit, and its waveform includes a portion that greatly vibrates as shown in FIG. 4 (b). Therefore, it causes a strong electromagnetic interference in the surroundings, and causes a malfunction of the power supply circuit, for example.

Further, an oscillating current is relaxed by inserting an inductance element in series with the discharge lamp, but the required inductance is relatively large and magnetic saturation does not occur against a large instantaneous current. Since a closed magnetic circuit cannot be used, the size of the inductance element is very large and the weight is large.

When the discharge lamp suffers a dielectric breakdown at a low voltage under the influence of temperature or the like and disappears without transition to glow discharge, or when the discharge lamp is turned off and then turned on again, This is inconvenient because it does not restart until the voltage applied to the electrodes reaches the set voltage.

If the power source connected to the electrodes of the discharge lamp can supply the voltage and current necessary for maintaining glow discharge and arc discharge, it can shift to the arc discharge state immediately after the dielectric breakdown of the enclosed gas. Further, in order to maintain the glow discharge state, a voltage of 100 V or more is required, but a current is relatively small. On the other hand, in order to maintain the arc discharge, the voltage may be about 60 V, but a current of 1 A or more is required, and in some cases, a power supply capable of flowing a current of 100 A or more is required. Therefore, if the glow discharge and the arc discharge can be maintained with a single power supply circuit, the heat loss in the power supply circuit in the arc discharge state becomes large, and a large waste is needed.

The present invention was devised to solve the above-mentioned problems, and does not cause heat loss in the power supply circuit.
An object of the present invention is to provide a discharge lamp lighting device that does not cause electromagnetic interference due to a sudden change in current and voltage, can be made light in weight, and has excellent relighting operability.

[0016]

Means for Solving the Problems] To solve the above problems, the present invention comprises a rectifier circuit connected to a commercial power source, this
A switching circuit having a semiconductor element connected to the rectifier circuit, the DC power supply circuit comprising a rectifier circuit and a smoothing circuit connected to the switching circuit, the straight
Current and voltage detector connected to the
Discharge connected to the voltage detector via the first diode
Lamp and a sudden voltage change placed directly in parallel with this discharge lamp.
Second capacitor that absorbs depletion, and the DC power supply circuit
An activation device comprising a second transformer and smoothing fourth capacitor and the second diode of the high-voltage generator which is connected to,
Provided between this starter and the discharge lamp, and above a certain voltage
A series connection circuit of a switching element and a resistor that conducts at,
The configuration of a discharge lamp lighting device is provided .

Further, it is convenient for the switching element to be configured to supply a set voltage to the discharge lamp in a state of being added to the discharge lamp until conditions for causing a dielectric breakdown of the gas enclosed in the discharge lamp are satisfied.

Further, it is convenient that the capacity of the second capacitor is smaller than that of the smoothing capacitor.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram showing the entire discharge lamp lighting device according to the present invention, FIG. 2 is a graph diagram showing a voltage-current relationship of characteristics of a switching element of the discharge lamp lighting device, and FIG. FIG. 3B is a graph showing the relationship between the lamp current and time, and FIG. 6B is a graph showing the starting voltage of the switching element.

As shown in FIG. 1, the discharge lamp lighting device A is
Commercial power supply 1 and rectifier circuit 2 connected to this commercial power supply 1
And a switching circuit 3 connected to this rectifying circuit 2.
A direct current power supply circuit 4 connected to the switching circuit 3, a current voltage detector 10 connected to the direct current power supply circuit 4, and a discharge connected to the current voltage detector 10 via a diode 11. Electric lamp 12 and this discharge lamp 12
A second capacitor 13 connected in parallel with the starter 20, a starter 20 connected to the DC power supply circuit 4, and the starter 2
0 and the discharge lamp 12 and a series connection circuit 29 including a switching element 27 and a resistor 28 provided in series.

As shown in FIG. 1, the DC power supply circuit 4 includes a transformer 5 and diodes 6 and 7 serving as a second rectifying circuit connected to a secondary winding of a main winding of the transformer 5.
And a choke coil 8 connected to the output side of the diodes 6 and 7, and a smoothing capacitor 9 (smoothing circuit) connected in parallel to the choke coil 8.

As shown in FIG. 1, the starter 20 has a resistor 21 and a diac 23 connected in series, and
A capacitor 22 connected in parallel to the resistor 21 and the diac 23, a high voltage generating transformer 24 provided on the rear side of the diac 23, and a diode 25 connected to the rear stage of the high voltage generating transformer 24. ,
It is composed of a smoothing capacitor 26 connected in parallel with the diode 25.

On the other hand, as shown in FIG.
Connection circuit 29 connected in series between the discharge lamp 12 and the discharge lamp 12
Is composed of a resistor 28 from the side of the discharge lamp 12 and a switching element 27 connected to the rear stage side of the resistor 28. As the switching element 27, a trigger element such as a spark gap or a diac is used. When the spark gap is used, there are two electrodes in the spark gap, and when a voltage is applied to those electrodes, the discharge start voltage is reached when a constant voltage is exceeded beyond the insulating state. Then, since the discharge starts between the electrodes of the spark gap, the voltage between the electrodes of the spark gap becomes a low voltage of several tens of volts. This state is the same as conduction between the electrodes of the spark gap, and the voltage has a low value as shown by in FIG.

The winding ratio of the transformer 24 is designed to be large, and the switching element 2
The winding ratio is such that a voltage that is at least twice the conduction start voltage of 7 can be generated.

Next, the operation procedure of the discharge lamp 12 will be described. As shown in FIG. 1, when the power supply 1 (see FIG. 1) is turned on, the rectifier circuit 2 converts the power into DC power. Then, the DC power by the switching circuit 3 is converted into high frequency power, to obtain a DC power necessary for arc discharge from the DC power supply circuit 4 side by the high-frequency power.

On the other hand, the starter 20 includes the diode 6,
The power from 7 is obtained, the high-frequency switch power is generated by the relaxation oscillation circuit using the trigger element such as the diac 23, and the high-voltage generating transformer 24 having a large step-up ratio is driven. Then, the output voltage of the starter 20 is supplied to the discharge lamp 12 through the series connection circuit 29 of the switching element 27 and the resistor 28. At this time, since the diode 11 is arranged in the DC power supply circuit 4, the high voltage of the starter 20 is not applied to the DC power supply circuit 4.

Since the series connection circuit 29 has the resistor 28, the instantaneous value of the current from the smoothing capacitor 26 to the discharge lamp 12 side is suppressed, and a sudden oscillating current can be eliminated. At this time, since the second capacitor 13 is connected in parallel to the discharge lamp 12 in which the current easily flows (glow discharge, arc discharge), the discharge lamp 1
The enclosed gas in 2 has little influence on the dielectric breakdown phenomenon that causes dielectric breakdown, but it is possible to suppress a rapid voltage change.

Therefore, at the moment when the switching element 27 becomes conductive, the electric charge of the smoothing capacitor 26 gently flows into the discharge lamp 12, and the lamp current of the discharge lamp 12 supplies a smooth current as shown in FIG. 3 (a). Can be achieved with desirable results for sustaining the discharge.

The capacity of the second capacitor 13 is
If it is smaller than the capacity of the smoothing capacitor 26,
When the switching element 27 is turned on and no dielectric breakdown occurs even when a high voltage is applied to the discharge lamp 12, the voltage of the second capacitor 13 is charged to a value close to the voltage of the smoothing capacitor 9. This is because the switching element 27 becomes conductive, so that the smoothing capacitor 26 and the second capacitor 1
3 is connected in parallel . Therefore, the electric charge accumulated in the smoothing capacitor 26 before the switching element 27 becomes conductive is changed to the smoothing capacitor 26 and the second capacitor.
Since it is distributed to both of the capacitors 13, the effect of increasing the voltage is quickly achieved.

Therefore, after that, the switching element 2 is again provided.
7 is conductive because the smoothing capacitor 26 is connected to the discharge lamp 12
Looking at the side, the switching element 27 and the second capacitor 13
Are connected in series, the voltage is the sum of the voltage of the second capacitor 13 and the conduction start voltage of the switching element 27 (see FIG. 3B).

Therefore, since a voltage higher than the initial voltage is applied to the discharge lamp 12, the discharge lamp 12 easily breaks down the enclosed gas, and the discharge lamp 12 easily shifts to arc discharge. Therefore, it is convenient in the case of relighting the discharge lamp 12 before the temperature of the enclosed gas is sufficiently lowered.

When the switching element 27 uses a diac which is a semiconductor element, its discharge start voltage is set as a breakover voltage. The breakover voltage is set to about 50V to 250V.

[0033]

Since the present invention is configured as described above, it has the following excellent effects. Since the discharge lamp lighting device is equipped with a series connection circuit consisting of a switching element and a resistor between the discharge lamp and the starter, when the discharge lamp is lit, abrupt changes in voltage and current are reduced and noise is generated. Can be controlled, and unstable operation due to noise in the power supply circuit at the start of discharge can be prevented.

The discharge lamp lighting device has a configuration in which a starter is connected in series with a switching element that conducts at a predetermined voltage or more and a resistor, and the series connection circuit is provided between the starter and the discharge lamp. By doing so, it becomes possible to operate the starter when necessary and surely stop the starter when the starter is not needed. for that reason,
The lighting operation of the discharge lamp can be performed accurately. Furthermore, glow discharge and arc discharge can be used with a single power supply circuit while minimizing heat loss. Also,
Since the second capacitor is connected in parallel with the discharge lamp, it is possible to absorb a sudden voltage change.

In the discharge lamp lighting device, since the second capacitor is connected in parallel to the discharge lamp, it is possible to supply the discharge lamp with a voltage higher than that of the main power supply circuit side when performing arc discharge from glow discharge. The service life of the electrodes of the discharge lamp can be extended without supplying an unnecessarily large current to the discharge lamp.

When the discharge lamp is turned on again, the discharge lamp lighting device is provided with the series connection circuit even when the temperature of the enclosed gas of the discharge lamp is not sufficiently lowered. Is supplied to the discharge lamp in a state where the set voltage is added, the relighting operation of the discharge lamp is fast and convenient.

Since the structure of the discharge lamp lighting device is simplified and the discharge lamp can be appropriately turned on, the structure of the device can be made compact and the weight can be reduced.

In the discharge lamp lighting device, since the capacity of the second capacitor connected in parallel with the discharge lamp is smaller than the capacity of the smoothing capacitor of the starter, even if a high voltage is applied to the discharge lamp, When the enclosed gas does not cause dielectric breakdown, the voltage of the second capacitor is charged close to the voltage value of the smoothing capacitor. Therefore, the switching element becomes conductive again after the voltage of the smoothing capacitor becomes the voltage obtained by adding the discharge starting voltage of the switching element to the voltage of the second capacitor. Therefore, the voltage of the second capacitor is applied to the discharge lamp at a voltage higher than the discharge starting voltage of the switching element, so that the enclosed gas of the discharge lamp easily causes dielectric breakdown, so that the discharge lamp is easily relighted. be able to.

The discharge lamp lighting device is provided with a switching element provided between the starter and the discharge lamp, and since the switching element additionally supplies a high voltage to the discharge lamp, a voltage higher than the discharge start voltage is emitted. It becomes possible to reliably insulate the charged gas of the discharge lamp by applying a load to the electric lamp.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an entire discharge lamp lighting device of the present invention.

FIG. 2 is a graph showing a voltage-current relationship of characteristics of a switching element of the discharge lamp lighting device of the present invention.

FIG. 3A is a graph showing a relationship between a lamp current and time according to the present invention, and FIG. 3B is a graph showing a starting voltage of a switching element.

FIG. 4 is a graph showing a current-voltage relationship at the start of lighting of a conventional discharge lamp.

[Explanation of symbols]

1 Commercial Power Supply 2 Rectifier Circuit 3 Switching Circuit 4 DC Power Supply Circuit 5 Transformer (First Transformer) 6 Diode (Rectifier Circuit) 7 Diode (Rectifier Circuit) 8 Choke Coil 9 Smoothing Capacitor (Smoothing Circuit) (First Condenser )
Capacitors) 10 current-voltage detector 11 diode (first diode) 12 discharge lamp 13 capacitor (second capacitor) 14 power control circuit 15 driver circuit 20 start 21 resistor 22 capacitor (third capacitor) 23 diac 24 transformer (second Transformer 25 Diode (second diode) 26 Smoothing capacitor (smooth fourth capacitor) 27 Switching element 28 Resistance

Claims (3)

(57) [Claims] Comprises a rectifier circuit as claimed in claim 1] is connected to a commercial power source, a switching circuit having a semiconductor element connected to the integer <br/> flow circuit, and a rectifier circuit and a smoothing circuit connected to the switching circuit DC power supply circuit and this DC power supply
Current voltage detector connected to the power supply circuit and this current
Discharge lamp connected to pressure detector via first diode
And a sudden voltage change directly in parallel with this discharge lamp
The second capacitor that absorbs electricity and the DC power supply circuit
An activation unit with a connected second transformer and smoothing fourth co <br/> Nden Sa and second diodes of the high-voltage generator, this
It is installed between the starter and the discharge lamp, and the
Equipped with a series connection circuit of a switching element and a resistor
The discharge lamp lighting apparatus, characterized in that was e. 2. The switching element is set to a voltage set until a condition for causing a dielectric breakdown of the gas enclosed in the discharge lamp is satisfied,
The discharge lamp lighting device according to claim 1, wherein the discharge lamp is supplied in a state of being added to the discharge lamp. 3. The discharge lamp lighting device according to claim 1, wherein the second capacitor has a capacity smaller than that of the smoothing capacitor.