CN101711083A - Lighting apparatus - Google Patents

Abstract

The present invention relates to a lighting device in which a discharge tube is provided inside an outer tube, the inner diameter of the outer tube is approximately equal to the outer diameter of the discharge tube, and in a high-pressure discharge lamp in which the outer tube is in contact with at least a part of the discharge tube, the difference in surface temperature is suppressed. The illuminance produced by equalization is not uniform. A high-pressure discharge lamp (10) is composed of a discharge tube (11) and an outer tube (20), and is lit by applying an AC voltage from a power supply unit (1) to a pair of electrodes (16) of the high-pressure discharge lamp (10). When lighting the lamp, the high-pressure discharge lamp (10) is cooled by circulating the cooling water (W) in the cooling water flow path (65), and the power supply unit (1) drives the inverter with the driving signal of the stable lighting frequency f1 to turn the The lamp (10) is turned on, but before the illuminance unevenness occurs, the frequency that can solve the illuminance unevenness is converted into a driving signal of a frequency f2 lower than the frequency, and the lamp (10) is turned on. In this way, the non-uniform density distribution of positive ions generated during stable lighting can be solved, and the non-uniform distribution of illuminance can be suppressed.

Description

lighting device

technical field

The present invention relates to a lighting device for a high-pressure discharge lamp comprising a discharge tube with both ends sealed, a pair of electrodes disposed opposite to each other, and at least metal enclosed, and an outer tube provided outside the discharge tube.

Background technique

For example, in curing treatment of resin such as an adhesive or exposure treatment of a printed circuit board, for example, a high-pressure discharge lamp (ultraviolet irradiation lamp) is used as an ultraviolet light source.

This high-pressure discharge lamp (ultraviolet irradiation lamp) becomes high temperature when the lamp is turned on, and is cooled as described in Patent Document 1.

Patent Document 1 describes a technique in which a water-cooled jacket with a double-tube structure is provided outside a discharge tube (hereinafter referred to as an arc tube in Patent Document 1), and cooling air flows between the arc tube and the inner tube of the water-cooled jacket. .

FIG. 10 shows the light source shown in FIG. 1 shown in Patent Document 1. As shown in FIG. As shown in the drawing, an ultraviolet irradiation lamp 101, a water cooling jacket 102, and end caps 103a and 103b at both ends of the water cooling jacket are provided. In the ultraviolet irradiation lamp 101 , a pair of electrodes are sealed at both ends of a straight quartz glass luminous tube 106 , and a rare gas, mercury, and metal halide are sealed inside.

The water-cooling jacket 102 is made of a transparent material such as cylindrical quartz glass, and becomes a double-tube structure formed by an inner tube 121 and an outer tube 122. Moreover, the cooling water 104 flows from the outside through the connecting tubes 123a and 123b at both ends. In the circulation sleeve, the adjacent light-emitting tube 106 is cooled through the air layer, and the heat radiated from the lamp 101 is absorbed at the same time.

One end cover 103a of the water cooling jacket 102 is provided with a cooling air vent 131, and the other end cover 103b is provided with an exhaust port 132. Moreover, cooling air 105 from the outside enters the inside of the water-cooling jacket 102 from the vent 131 as shown by the arrow, flows in the space between the luminous tube 106 and the inner tube 121 of the water-cooling hood 102, and takes heat from the surface of the luminous tube to cool the light. Tube 106.

From the numerical example described in the paragraph number [0011] of Patent Document 1, described in Patent Document 1, it can be read that the outer diameter of the luminous tube 106 is 24 mm, the inner tube 121 of the water cooling jacket is 26 mm, and the gap between the two is 1mm (=1000μm).

FIG. 10( b ) shows a cross-sectional view of the arc tube 106 and the inner tube 121 described in Patent Document 1 taken along a plane perpendicular to the tube axis direction.

The cooling described in Patent Document 1 cannot sufficiently cool the high-pressure discharge lamp (ultraviolet irradiation lamp), so the technology described in Patent Document 2 has recently been developed.

According to Patent Document 2, the high-pressure discharge lamp has a double-tube structure, and the gap between the discharge tube and the outer tube located outside is close to the gap, and the cooling effect on the discharge tube is improved by cooling water flowing around the outer tube.

FIG. 11 shows a cross-sectional configuration of the light irradiation device shown in Patent Document 2, and FIG. 12 shows a cross-sectional configuration of a discharge tube and an outer tube of the light irradiation device shown in FIG. 11 . In addition, FIG. 12(b) is a cross-sectional view taken along line B-B in FIG. 12(a).

This light irradiation device includes a high-pressure discharge lamp 10 as a light source. The high-pressure discharge lamp 10 is composed of a discharge tube 11 which is generally rod-shaped, and an outer tube 20 made of, for example, quartz glass, which is arranged inside the discharge tube 11 .

The discharge tube 11 is inside a straight tube-shaped inner tube 12 made of, for example, quartz glass which is sealed at both ends, and a pair of rod-shaped electrodes 16 made of, for example, tungsten are arranged opposite to each other. A metal foil 17 made of, for example, molybdenum in the rod-shaped sealing portion 13 of the inner tube 12 is electrically connected to an external lead 18 extending axially outward from the outer end of the sealing portion 13 .

In the gap between the discharge tube 11 and the outer tube 20 of the high-pressure discharge lamp 10, an air layer or a gas layer made of an appropriate gas is formed.

This light irradiation device is provided so as to extend along the tube axis of the above-mentioned high-pressure discharge lamp 10, and forms a cooling water flow path 65 through which the cooling water W flows between the outer peripheral surface of the high-pressure discharge lamp 10 and the cooling water. The cylindrical cooling jacket 60, and the cooling water supply channel forming member 61 arranged in the inner spaces of both ends of the high pressure discharge lamp 10 and the cooling jacket 60 communicate with the cooling water channel 65 between the high pressure discharge lamp 10 and the cooling jacket 60, and The cooling water is discharged from the cooling mechanism constituted by the flow path forming member 62 .

And, on the back side of the high-pressure discharge lamp 10 with respect to the light irradiation direction (in FIG. 11, the downward direction), for example, a trough-shaped reflector 70 having a parabolic reflective surface 71 in cross-section has a first focal point and the high-pressure discharge lamp 10. The center (the straight line connecting the centers of the pair of electrodes 16 of the high-pressure discharge lamp 10) is aligned, and is arranged to extend along the high-pressure discharge lamp 10, and the light emitted from the high-pressure discharge lamp 10 is directly or by using the reflector 70 The reflected light passes through the mask M held on the mask 75 as parallel light, and irradiates the workpiece such as a liquid crystal panel or a semiconductor element on which a photosensitive agent such as a photoresist is applied and placed on the workpiece stage 76. 77.

In the light irradiation device described above, when the high-pressure discharge lamp 10 is turned on, the cooling water W is supplied by an appropriate cooling water supply mechanism (pump) not shown.

The supplied cooling water W flows through the cooling water channel 65 formed between the high-pressure discharge lamp 10 and the cooling jacket 60 , flows through the wall surface of the high-pressure discharge lamp 10 , specifically along the outer peripheral surface of the outer tube 20 toward the After cooling the entire high-pressure discharge lamp 10 by flowing in the axial direction, it is discharged through the cooling water discharge channel forming member 62 .

In the discharge tube of these high-pressure discharge lamps, Hg, or cations such as Fe, Tl, Sn, Zn, In, etc. are enclosed together with Hg, and these are excited during lamp lighting to emit light.

Patent Document 1: Japanese Patent Application Laid-Open No. 06-267512

Patent Document 2: Japanese Patent Laid-Open No. 2008-146962

Contents of the invention

Reduce the average gap between the discharge tube and the outer tube where the cooling water flows on the outer peripheral surface, that is, reduce the difference between the outer diameter of the discharge tube and the inner diameter of the outer tube. For example, if the average gap is 100 μm or less, the discharge tube The case where the illuminance distribution in the longitudinal direction becomes non-uniform (so-called non-uniform illuminance). This is the situation described in Patent Document 1 and will not occur.

As a result of intensive examination by the inventors of the present invention, it was found that this is caused by making the gap smaller than that described in Patent Document 1.

Specifically, the member constituting the discharge tube and the outer tube is a glass member, so its surface shape is undulating and uneven. Therefore, the gap between the discharge tube and the outer tube is subject to fluctuations of ±100 μm, for example, and the average gap is, for example, 100 μm or less. When, the gap becomes more than 100% fluctuation.

In other words, the discharge tube and the outer tube are in contact at some places, and there is a gap of, for example, 200 μm or less at other places. If the cooling water flows on the outer peripheral surface of the outer tube, the discharge tube will be efficiently cooled because the abutting part has good thermal conductivity. For this reason, the part with a gap of 200 μm has poor thermal conductivity than the abutting part, so there is no efficiently cooled. Also in the longitudinal direction of the discharge tube, there are portions that are efficiently cooled and portions that are not cooled.

Inside the discharge tube, Hg is sealed, or cations such as Fe, Tl, etc. are sealed together with Hg. These cations are in a thermal equilibrium state where the temperature is low, and the density becomes high, while the density becomes low in the high temperature part. Therefore, in the case of the high-pressure discharge lamp described in Patent Document 2, in the longitudinal direction, it is efficiently absorbed. The cooling part makes the density of cations higher, while in the uncooled part, the density becomes lower. In this way, in the longitudinal direction of the discharge tube, the density distribution of cations becomes non-uniform, and the illuminance distribution becomes non-uniform (non-uniform illuminance).

In addition, in the case of Patent Document 1, the average gap is 1000 μm, and even if the gap is fluctuated by, for example, ±100 μm due to fluctuations in the outer shapes of the discharge tube and the outer tube, the variation in the gap is only about 10%. Therefore, in the high-pressure discharge lamp described in Patent Document 1, the cooling distribution in the longitudinal direction hardly occurs, and the illuminance distribution does not become non-uniform (illuminance non-uniformity).

The present invention is created in view of the above circumstances. The purpose of the present invention is to provide a discharge tube and an outer tube arranged outside it. The inner diameter of the outer tube is almost equal to the outer diameter of the discharge tube, and the outer tube and the discharge tube have at least A lighting device and a lighting method for suppressing unevenness in illuminance in a partially contacted high-pressure discharge lamp.

In the present invention, the above-mentioned problems are solved by performing the following processes.

(1) It is provided with both ends sealed, a pair of electrodes disposed opposite to each other inside, and at least a rod-shaped discharge tube made of metal is enclosed, and an outer tube provided outside the discharge tube, the inner diameter of the outer tube is the same as that of the discharge tube. The outer diameter of the discharge tube is approximately equal, the outer tube and the discharge tube are in contact at some places, and the average value of the difference between the inner diameter of the outer tube and the outer diameter of the discharge tube is, for example, about 100 μm for a high-pressure discharge lamp, and along the high-pressure discharge lamp a flow path forming member extending from the tube axis to form a flow path through which cooling water flows between the outer tube of the high pressure discharge lamp; and a power supply unit electrically connected to the pair of electrodes to supply power to the high pressure discharge lamp In the lighting device thus configured, the power supply unit is configured as follows.

That is, a first signal having a stable lighting frequency f1 for lighting the high-pressure discharge lamp and a first signal having a frequency f2 lower than the stable lighting frequency f1 for solving uneven illuminance of the high-pressure discharge lamp are generated. A signal generating mechanism for 2 signals; and a conversion mechanism for selectively outputting the above-mentioned first signal or the second signal; and driven by the above-mentioned first signal or the second signal, and supplies an AC voltage of frequency f1 or frequency f2 to the above-mentioned It is composed of the inverter circuit of the high pressure discharge lamp. In this way, the high-pressure discharge lamp is turned on at the stable lighting frequency f1, and the lamp 10 is turned on at the frequency f2 lower than the frequency that can solve the unevenness of the illuminance before the unevenness of the illuminance occurs.

(2) In the above (1), the switching mechanism has a timing mechanism, and by this timing mechanism, the AC voltage supplied to the high-pressure discharge lamp will be supplied to the high-pressure discharge lamp The frequency is reduced from f1 to f2, and the AC voltage of the frequency f2 is supplied to the high pressure discharge lamp during a second predetermined time period.

(3) In the above (1) and (2), the relationship between the stable lighting frequency f1 [Hz] and the frequency f2 [Hz] is f2≦0.3f1.

(4) In the above (1), (2), and (3), the metal enclosed in the discharge tube contains mercury, and the stable lighting frequency f1 [Hz] is the density of mercury enclosed in the discharge tube [ mg/cm ³ ] as Hg, and the inter-electrode distance [m] as AL, f1<(Hg/30) ^-0.33 ×250/AL.

In the present invention, the following effects can be obtained.

(1) generating a first signal having a stable lighting frequency f1 and a second signal having a frequency f2 having a low f1 for solving uneven illumination, and switching the first signal and the second signal to light the high-pressure discharge lamp, Therefore, it is possible to solve the non-uniform density distribution of positive ions that occurs during stable lighting, and to suppress the uneven distribution of illuminance (non-uniform illuminance).

That is, by switching to a frequency f2 lower than the frequency f1, the cations can be pulled to one electrode side, and the uneven density distribution of the cations that occurs when lighting is performed at the stable lighting frequency f1 can be solved and suppressed. The resulting illuminance is not uniform.

(2) By switching the frequency of the AC voltage supplied to the high-pressure discharge lamp using a timing mechanism, uneven illuminance distribution (nonuniform illuminance) can be suppressed without hindering practical use with a relatively simple mechanism.

(3) By making the relationship between the stable lighting frequency f1 [Hz] and the frequency f2 [Hz] f2≦0.3f1, unevenness in illuminance can be effectively resolved.

(4) The stable lighting frequency f1 [Hz] is f1 < (Hg/ ³⁰ ) ^{- 0.33} × 250/AL, which can suppress acoustic resonance and suppress color unevenness caused by gas distribution or coarse and dense standing waves of generated ions.

Description of drawings

Fig. 1 is a schematic cross-sectional view showing the structure of a high-pressure discharge lamp according to an embodiment of the present invention.

Fig. 2 is a sectional view showing line A-A of Fig. 1 .

Fig. 3 is a schematic cross-sectional view showing the structure of a high-pressure discharge lamp according to an embodiment of the present invention.

Fig. 4 is a diagram showing a detailed configuration of a power supply unit according to the first embodiment of the present invention.

FIG. 5 is a detailed diagram showing a drive circuit of the control unit shown in FIG. 4 .

FIG. 6 is a flowchart showing the operation of the control unit.

FIG. 7 is a timing chart for explaining the operation of the control unit.

Fig. 8 is a configuration diagram showing a power supply unit according to a second embodiment of the present invention.

Fig. 9 is a diagram showing the configuration of the light irradiation device used in the experiment, and the measurement position and illuminance.

FIG. 10 is a diagram showing the configuration of a conventional light source.

FIG. 11 is a diagram showing the configuration of a conventional light irradiation device.

Fig. 12 is a diagram showing a discharge tube and an outer tube of the light irradiation device shown in Fig. 11 .

(Description of main component symbols)

1: Power supply part, 2: Step-up rectification circuit, 2a: AC power supply, 2b: Control circuit, 3: Full-bridge inverter circuit, 4: Starting circuit, 5: Control part, 5a: Basic frequency oscillation circuit, 5b: Timing circuit, 5c: low frequency oscillation circuit, 5d: drive circuit, 5e: comparison circuit, 5f: feedback control circuit, 10: high pressure discharge lamp, 11: discharge tube, 12: inner tube, 13: sealing part, 16: electrode , 17: metal foil, 18: external wire, 20: outer tube, 60: cooling jacket, 61: cooling water supply flow path forming member, 62: cooling water discharge flow path forming member, 63, 64: 123 locking part, 65: cooling water flow path, 70: reflector, 75' curtain platform, 76: workpiece platform, 77: workpiece, T1: step-up transformer, D1: polar body, C1: smoothing capacitor, C2: capacitor, LL1, LL3: Coil, S1: switching element, SL: conversion circuit, DD1: delay circuit, PS1, PS2, PS3: illuminance meter, W: cooling water, M: mask, Q1~Q4: switching element, L1~L8: logic circuit.

Detailed ways

First, a light irradiation device targeted by the present invention will be described.

The light irradiation device of the present invention is provided with a high-pressure discharge lamp similarly to that shown in FIG. 11 above, and is provided with a flow path for partitioning the flow path through which the cooling water for cooling the lamp flows along the wall surface of the outer tube when the lamp is turned on. Form the composition of components.

FIG. 1 is a schematic sectional view showing the configuration of a light irradiation device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a line A-A in FIG. 1 .

This light irradiation device is equipped with a high-pressure discharge lamp 10 as a light source. The cylindrical cooling jacket 60 of the flow path forming member forming the cooling water flow path 65 through which the cooling water W flows is interposed therebetween.

At both ends of the high-pressure discharge lamp 10 and the cooling jacket 60, a cooling water supply flow path forming member 61 and a cooling water discharge flow path forming member 61 having an internal space communicating with the cooling water flow path 65 between the high-pressure discharge lamp 10 and the cooling jacket 60 are arranged. The member 62 constitutes a cooling mechanism by these.

The cooling water supply flow path forming member 61 and the cooling water discharge flow path forming member 62 are substantially L-shaped tubes as a whole, and are connected to the high pressure discharge lamp 10 and the cooling jacket 60 such that the tube axis extends horizontally.

Furthermore, the outer peripheral surface of the cooling jacket 60 is held and fixed by, for example, an O-ring (not shown) through the locking port 63 on the inner side in the axial direction, and the locking port 64 on the outer side in the axial direction, for example, via an O-ring. A ring (not shown) holds and fixes the outer peripheral surface of the high pressure discharge lamp 10 .

The cooling jacket 60 is made of a material that transmits ultraviolet rays radiated from the high-pressure discharge lamp 10 , such as quartz glass.

Regarding the light irradiation direction (downward direction in FIGS. 1 and 2 ), on the back side of the high-pressure discharge lamp 10, the center of the first focal point and the center of the high-pressure discharge lamp 10 (connecting the pair of electrodes 16 of the high-pressure discharge lamp 10) In a state where the straight line in the center) coincides with each other, a trough-shaped reflector 70 having a parabolic reflective surface 71 in cross-section, for example, is arranged to extend along the high-pressure discharge lamp 10 .

The light emitted from the high-pressure discharge lamp 10 is directly or reflected by the reflector 70 as parallel light, and is irradiated on the workpiece platform 76 via the mask M held on the mask platform 75, for example, A workpiece 77 such as a liquid crystal panel or a semiconductor element coated with a photosensitive agent such as a photoresist.

Here, the reflective surface 71 is formed by alternately evaporating a multilayer film formed by different reflective layers such as titanium dioxide and silicon dioxide.

The power supply unit 1 is electrically connected to a pair of electrodes 16 of the high pressure discharge lamp 10 via an external lead 18 , and an AC voltage is applied between the pair of electrodes from the power supply unit 1 to light the high pressure discharge lamp 10 .

When lighting the high-pressure discharge lamp 10, the cooling water W is supplied by an appropriate cooling water supply mechanism (pump) not shown. Here, the cooling of the high-pressure discharge lamp 10 can be achieved by circulating the cooling water W at a flow rate of, for example, 5 liters (L)/min.

The supplied cooling water W flows along the wall surface of the high pressure discharge lamp 10 , specifically along the outer peripheral surface of the outer tube 20 , through the cooling water channel 65 formed between the high pressure discharge lamp 10 and the cooling jacket 60 .

The following description will focus on the above-mentioned high-pressure discharge lamp 10 .

The high-pressure discharge lamp 10 is a double-tube structure in which the inner diameter of the outer tube 20 is approximately equal to the outer diameter of the discharge tube 11, the outer tube 20 and the discharge tube 11 are in contact with each other, and the average gap between the outer tube and the discharge tube is 100 μm or less.

In addition, the average gap mentioned here means that before the assembly of the outer tube 20 and the discharge tube 11, the inner diameter L4 of the outer tube 20 and the outer diameter L5 of the discharge tube 11 are measured at multiple locations, and the difference component is taken as 1/2. The average value of refers to the case of the average value of the gaps in the radial direction between electrodes measured at a plurality of positions in the effective light emitting region.

For example, the inner diameter L4 of the outer tube 20 is obtained as follows.

Measure the outer diameter L1 of the outer tube 20 before assembling the outer tube 20 and the discharge tube 11, and measure the thickness L2 of the thicker part and the thickness L3 of the thinner part of the outer tube 20, and use L4=L1-L2-L3 to find The inner diameter L4 of the outer tube 20.

In addition, the outer diameter L5 of the discharge tube 11 is the outer diameter of the discharge tube 11 measured before the outer tube 20 and the discharge tube 11 are assembled.

Fig. 3 is a schematic cross-sectional view showing the structure of a high-pressure discharge lamp according to an embodiment of the present invention.

As shown in FIG. 11 above, this high-pressure discharge lamp 10 is inside a straight tube-shaped inner tube 12 made of, for example, quartz glass which is sealed at both ends, and a pair of rod-shaped electrodes 16 made of, for example, tungsten are arranged opposite to each other. The metal foil 17 made of, for example, molybdenum formed in the rod-shaped sealing portion 13 of the inner tube 12 is electrically connected to the external lead protruding outward in the axial direction from the outer end of the sealing portion 13 via airtightly embedded in each electrode 16. 18 as a whole is composed of a rod-shaped discharge tube 11 and an outer tube 20 made of, for example, quartz glass in which the discharge tube 11 is disposed. Both end portions of the discharge tube 11 and the outer tube 20 are fixed by an adhesive 24 via a socket 25 .

The sealing portion 13 of the discharge tube 11 is formed, for example, by making the both ends of the tube body of the constituent material of the inner tube 12 into a melted state, and shrinking and sealing the interior of the decompressed portion, and is formed to be smaller than the central portion of the discharge tube 11 (equivalent to the light emission). part of the field) to trails.

The high-pressure discharge lamp 10 is a high-pressure mercury lamp or a metal halide lamp. Mercury of, for example, 1 mg/mm ³ or more is sealed inside the discharge tube 11, and a rare gas such as argon gas is sealed in an appropriate amount. In addition, halogen compounds such as iron (Fe), thallium (Tl), tin (Sn), zinc (Zn), and indium (In) may be sealed together with mercury (Hg), and there are also mercury (Hg)-free By. In this way, for example, light including ultraviolet light having a wavelength of 350 to 450 nm is emitted.

As shown in FIG. 1 , a power supply unit 1 is electrically connected to a pair of electrodes of a high-pressure discharge lamp 10 .

Fig. 4 is a diagram showing a detailed configuration of a power supply unit according to the first embodiment of the present invention.

The power supply unit 1 is composed of: a step-up rectifier circuit 2 supplied with a DC voltage, and a full-bridge inverter circuit 3 connected to the output side of the step-up rectifier circuit 2 and changing the DC voltage into an AC voltage to supply the discharge lamp 10 , and between the full-bridge inverter circuit 3 and the high-pressure discharge lamp 10 are connected in series to the coil LL1 of the high-pressure discharge lamp 10, the starting coil LL2 and the starter circuit 4, and control the switching elements of the full-bridge inverter circuit 3 ( For example, the control unit 5 for driving the IGBT).

The step-up rectification circuit 2 is connected to the AC power supply 2a, and is a rectification circuit composed of a step-up transformer T1, a rectifier diode D1, and a smoothing capacitor C1, which converts the AC voltage into a DC voltage, and the subsequent coil LL3 , the switching element S1 , the diode D1 , and the capacitor C2 , the boosted DC voltage is supplied to the full-bridge inverter circuit 3 .

The control circuit 2b is connected to the switching element S1 such as IGBT or FET of the step-up chopper circuit, and a desired voltage can be supplied by changing the switching frequency and the switching period of the switching element S1.

The full-bridge inverter circuit 3 is composed of switching elements Q1 to Q4 such as IGBTs or FETs connected in a bridge shape. The switching elements (ON, OFF) of the full-bridge inverter circuit 3 are driven by the drive circuit described below.

The operation of the full-bridge inverter circuit 3 alternately repeats switching elements Q1, Q4 and switching elements Q2, Q3. When the switching elements Q2 and Q3 are turned on, the current flows in the boost rectifier circuit 2→switching element Q3→coil LL1→starting coil LL2→discharge lamp 10→switching element Q2→boost rectifier circuit 2.

On the one hand, when the switching elements Q1 and Q4 are turned on, the AC rectangular wave current is passed through the step-up rectification circuit 2 → switching element Q1 → discharge lamp 10 → starting coil LL2 → coil LL1 → switching element Q4 → step-up rectification circuit A path of 2 is supplied to the discharge lamp 10 .

The control unit 5 is composed of a multivibrator, an LC oscillation circuit, etc., and consists of a fundamental frequency oscillation circuit 5a that transmits a signal A of a fundamental oscillation waveform, and a low frequency oscillation circuit 5c that transmits a signal B that is lower in frequency than the signal A, and a timing circuit 5b that sends a timing signal T that switches on and off at a predetermined time. The signals A, T, and B output by the fundamental frequency oscillating circuit 5a, the timing circuit 5b, and the low frequency oscillating circuit 5c are combined by the driving circuit 5d.

Signal synthesis for controlling the full-bridge inverter circuit 3 by combining the signals A, B, and T will be described with reference to FIGS. 5 to 7 .

FIG. 5 is a detailed diagram showing a drive circuit.

The signal A having the frequency f1 output by the oscillation circuit 5a is input to one input terminal of the logic circuit L1 (AND circuit), and the timing circuit 5b is input to the other input terminal of the logic circuit L1. output signal T. As shown in FIG. 7 below, the output signal T of the timing circuit 5b is, for example, changed from a high level (H level) to a low level (L level) or from a low level (L level) when the signal A falls. Standard) is changed to a high level (H level) signal, the state of the first predetermined cycle of signal A is changed from H to L level, and the state of signal A is changed from L to H level in the second predetermined cycle .

The logic circuit L1 outputs the signal A when the output of the timing circuit 5b is at the H level.

Furthermore, the output signal T of the timer circuit 5b is input to the logic circuit L2 (inverting circuit) to be inverted, and input to one input terminal of the logic circuit L3 (AND circuit). The output [signal B having a frequency f2 (f2<f1)] of the low-frequency oscillation circuit 5c is input to the other input terminal of the logic circuit L3. The logic circuit L3 outputs the signal B when the output signal T of the timing circuit 5b is at the L level.

The output of the logic circuit L1, L2 is input to the input terminal of the logic circuit L4 ("or" circuit), and the logic circuit L4 is when the output of the timing circuit 5b is H level, then the output signal A, and when the timing circuit 5b When the output of the L bit is accurate, the signal B is output. That is, the switching circuit SL is composed of the timing circuit 5b and the logic circuits L1, L2, L3, L4, and the switching circuit SL selectively outputs the signal A or the signal B in response to the output signal T of the timing circuit 5b.

The output signal C1 of the logic circuit L4 is input to the delay circuit DD1, and the delay circuit DD1 is a signal C2 that outputs the delayed signal C1. The signals C1 and C2 are input terminals of a logic circuit L5 (AND circuit), and the logic circuit L5 is a signal X that outputs an AND signal thereof. This signal X serves as a drive signal for the switching elements Q1 and Q4 of the full-bridge inverter circuit 3 .

Moreover, the signals C1 and C2 are inverted in the logic circuits L6 and L7 (inverting circuits), and then input to the input terminals of the logic circuit L8 ("AND" circuit), and the logic circuit L8 outputs its "AND" signal The signal Y is a driving signal for the switching elements Q2 and Q3 of the full-bridge inverter circuit 3 .

FIG. 6 is a flowchart showing the operation of the control unit, FIG. 7 is a sequence diagram showing the control unit, and the operation will be described using FIGS. 5 , 6 , and 7 .

First, in step S1, the signal A of the basic oscillation waveform is produced from the basic frequency oscillation circuit 5a.

Then, in step S2, lighting waveforms and timing waveforms of frequencies f1 and f2 are generated based on the basic oscillation waveform. That is, based on the signal A output by the oscillation circuit 5a, a signal B with a lower frequency than the signal A is produced in the low-frequency oscillation circuit 5c, and a signal B that is switched on and off at a predetermined time is produced in the timing circuit 5b using the signal A. Timing signal T.

In step 3, signal A (frequency f1), signal B (frequency f2) and signal T are combined to produce driving signals X, Y for switching elements Q1-Q4 composed of IGBTs of the full-bridge inverter circuit.

In step 4, the switching elements Q1 to Q4 are switched on and off according to the X and Y waveforms, and AC lighting is performed.

That is, while the signal T is at the H level, the signals X and Y of the stable lighting frequency f1 are output, and the high pressure discharge lamp is turned on at the stable lighting frequency f1.

Next, the high-pressure discharge lamp is turned on at a frequency f2 lower than the stable lighting frequency f1 after a predetermined time has elapsed since the high-pressure discharge lamp is turned on at the stable lighting frequency f1 before illuminance unevenness occurs, using the signal T as the L level.

At this time, the cations of the discharge tube of the high-pressure discharge lamp are input at a low frequency, so that the time for being pulled to the cathode becomes longer, and the cations in the plasma are disturbed. The stirring effect will make the distribution of cations uniform, and when the stable lighting frequency f1 is input, it can also solve the uneven distribution of cations and suppress the unevenness of illuminance.

In addition, in the fifth circuit, a delay circuit DD1 is set to generate a delayed signal C2 to carry out the logical product of the signal C1 and the signal C2 (or its inverted signal), and when the signal X is turned on and the signal Y During the ON period, set both signals to OFF period. This is to solve the problem that the switching elements Q1 to Q4 will be destroyed if they are turned on simultaneously, and a dead time is formed.

In this embodiment, a signal A having a stable lighting frequency f1 and a signal B having a frequency f2 lower than f1 are generated, and the timing circuit 5b switches the signal A and the signal B every predetermined time, and the stable lighting frequency The signal of f1 and the signal of frequency f2 lower than its frequency, which can solve the problem of uneven illuminance, drive the switching elements Q1 to Q4 of the full-bridge inverter circuit 3 to light the high-pressure discharge lamp. The density distribution of positive ions at the time of stable lighting is not uniform, and it is possible to suppress that the illuminance distribution becomes non-uniform (non-uniform illuminance).

That is, by switching to a frequency f2 lower than the stable lighting frequency f1 every predetermined time, the positive ions are pulled to one electrode side, and the uneven density distribution of the positive ions that occurs when the light is turned on at the stable lighting frequency f1 can be resolved. In addition, unevenness in illuminance caused by this can be suppressed.

In addition, since the time when the illuminance unevenness occurs in the high-pressure discharge lamp is known in advance, the signal T of the timer circuit 5b is set at the timing of switching the signals A and B at a predetermined time before the illuminance unevenness occurs in the high-pressure discharge lamp.

In addition, as shown in the following experimental results, when the low frequency f2 is 5 Hz or more and 30% or less of the stable lighting frequency f1, the deformation of the electrode can be suppressed, and the illuminance unevenness can be effectively suppressed.

In addition, it is preferable to insert the low frequency f2 into the stable lighting frequency f1 before the uneven distribution of positive ions occurs. Therefore, it is preferable to insert the low frequency f2 within 10 minutes after starting the lighting at the stable lighting frequency f1.

Also, the period during which the low frequency f2 is inserted is 1 cycle to 10 cycles (1 cycle is the on-off period of the signal of the frequency f2), and the period during which the light is turned on at the stable lighting frequency f1 is 0.1 to 6 seconds. range is better.

In addition, the period of lighting at the low frequency f2 and the cycle of lighting at the low frequency f2 are determined according to the specifications of the lamp, lighting conditions, the contact area or the number of contact parts between the outer tube and the luminous tube, etc. .

Here, in a lamp for AC lighting, it has been known that illuminance unevenness occurs due to acoustic resonance (for example, refer to the 15th line in the upper left column on page 2 of JP-A-63-285899, etc.). .

Acoustic resonance occurs when the condition of the following formula (1) is satisfied. However, fa represented by the following formula (1) is an acoustic resonance frequency, m is a constant, V is a sound velocity (m/s), and AL is a distance between electrodes (unit: m).

fa＝mv/(2AL) …(1)

Under the condition of satisfying the formula (1), it is known that dense standing waves of gas molecules or ionized ions (referred to as "acoustic resonance") occur in the axial direction of the lamp to cause color unevenness.

The speed of sound V in formula (1) can generally be expressed by specific heat ratio γ, density p (unit: kg/m ³ ) and pressure ρ (unit: N/m ² ) [refer to sub-equation (2)].

v＝(γp/ρ) ^0.5 …(2)

Substituting the formula (2) into the formula (1), it becomes the following formula (3).

fa＝m(γp/ρ) ^0.5 /(2AL) …(3)

The acoustic resonance frequency fa depends on the vapor pressure, gas density, temperature, etc. of the enclosure.

In the actual lamp, these values are not the same, and there is a large dependence distribution on the lamp size (inner diameter, distance between electrodes, ratio of these), lighting conditions (input), and cooling conditions of the discharge tube (inner surface temperature, etc.), Therefore, it must be determined experimentally and rigorously.

The purpose of the present invention is to suppress unevenness in illuminance, and since the unevenness in illuminance also occurs through acoustic resonance as described above, it is preferable to also suppress acoustic resonance.

Then, it was found experimentally that the stable lighting frequency f1 of the present invention does not satisfy the range of the above-mentioned acoustic resonance frequency fa.

As a result, it is known that the following condition (4) is satisfied approximately. However, Hg represented by the condition (4) is the density of enclosed mercury (unit: mg/cm ³ ). AL is the same inter-electrode distance (unit: m) as above.

f1＜(Hg/30) ^-0.33 ×250/AL …(4)

In the lighting device of FIG. 4, the conversion circuit SL composed of the timing circuit 5b and the logic circuits L1-L4 converted at a predetermined time is used to convert the signal A and the signal B, but as a mechanism for converting the signal A and the signal B, and It is not limited to the timer circuit, and the mechanism described below may be used.

FIG. 8 is a configuration diagram showing a power supply unit according to a second embodiment of the present invention, and another configuration example will be described using the same diagram.

In the lighting device shown in FIG. 8, a plurality of illuminometers PS1, PS2, PS3, ... are arranged along the longitudinal direction of the high-pressure discharge lamp, and a comparison circuit 5e for mutually comparing the measurement results made by the illuminometers is provided, and when the The feedback control circuit 5f that switches the signal A and the signal B when the phase difference of the output becomes more than a certain value.

That is, instead of the timing circuit 5b in FIG. 4, a comparison circuit 5e and a feedback control circuit 5f are provided, and the signal A and signal B are converted by the feedback control circuit 5f according to the comparison result of the comparison circuit 5e.

FIG. 8 differs only in the circuit that generates the signal T for operating the drive circuit 4d. The other configurations are basically the same as those shown in FIG. 4. Hereinafter, only the differences from FIG. 4 will be described.

When the lamp is turned on, a plurality of illuminometers PS1, PS2, PS3, ... are provided so as to be located in the radial direction between the electrodes of the high pressure discharge lamp 10 (hereinafter, three illuminometers PS1, PS2, PS3 are provided). illustrate).

The plurality of illuminance meters PS1, PS2, and PS3 are illuminance meters that measure the longitudinal direction of the high-pressure discharge lamp 10, and send the results to the comparison circuit 5e. The comparison circuit 5e compares the measurement results of the illuminance meters PS1, PS2, PS3, ..., and if there is a deviation of a certain value or more in the measurement results, the conversion signal D is sent to the feedback control circuit 5f.

The feedback control circuit 5f sends a signal to switch the lighting frequency to the drive circuit 5d when the illuminance distribution in the longitudinal direction of the high pressure discharge lamp 10 deviates from a predetermined range. That is, the feedback control circuit 5f sets the signal E to L level, and the drive circuit 5d sets the signal E to L level. Then, the frequency of the driving signals X, Y of the switching elements Q1 to Q4 of the full-bridge inverter circuit is converted from the stable lighting frequency f1 to f2.

Thus, when the variation in the measurement result of the illuminometer is resolved, the comparator circuit 5e stops the transmission of the conversion signal D, and the feedback control circuit 5f sets the signal E to the H level. The driving circuit 5d restores the frequency of the driving signals X, Y of the switching elements Q1 to Q4 of the full-bridge inverter circuit to the stable lighting frequency f1 when the signal E reaches the H level.

The predetermined range mentioned here refers to the range in which the uniformity of the allowable illuminance distribution can be maintained by the irradiated object irradiated by the ultraviolet rays from the high-pressure discharge lamp 10, such as Refers to the situation of ±10% illuminance distribution.

In addition, the internal configuration of the drive circuit is basically the same as that shown in FIG. 5, and its operation is also shown in FIG. 7. In FIG. 5, the above-mentioned signal E is input to the terminal to which the signal T is input.

The difference between the above-mentioned first embodiment and this embodiment is that the timing of switching from the stable lighting frequency f1 to f2 is different from the predetermined time in the first embodiment, but whether it deviates from the predetermined illuminance distribution in the present embodiment The circumstances are different, but the other functions and effects are common.

In order to confirm the effects of the present invention, the following experiments were conducted.

(1) Experimental example 1

The configuration of the light irradiation device used in the experiment is shown in FIG. 9( a ), which has the same configuration as the light irradiation device shown in FIG. 1 above, and its specifications are as follows.

Discharge tube (light-emitting tube): inner diameter 5.4mm outer diameter 9mm

Outer tube: inner diameter 9.15mm outer diameter 12mm

·Distance between electrodes: 500mm

·Enclosure

Mercury density 5mg/cm ³

The flow rate of cooling water flowing between the water cooling jacket and the outer pipe: 20L/min

The lighting condition of the high-pressure discharge lamp used in the experiment is to input the stable lighting frequency f1 for 1 second, and then input the frequency f1 and f2 alternately in such a way that the low frequency f2 is input into the 1-cycle component (the opening and closing of the frequency f1 is regarded as 1 cycle). signal of. That is, the steady lighting frequency f1 is 1 second → the low frequency f2 is 1 cycle → the steady lighting frequency f1 is 1 second → ) ... (hereinafter the same).

The lighting frequency is as follows.

·Stable lighting frequency f1: 100, 500, 800, 1000Hz

Low frequency f2: 3, 5, 10, 30, 50, 100, 150, 200, 300, 500Hz

A plurality of illuminometers were arranged on the radially outward side between electrodes of the high-pressure discharge lamp used in the experiment via a cooling jacket. This multiple illuminance meter is arranged along the longitudinal direction of the high pressure discharge lamp, and measures the illuminance distribution in the longitudinal direction.

The illuminometers were arranged at 10 mm intervals in the longitudinal direction of the high-pressure discharge lamp at a distance of 5 cm from the electrode tip in the axial direction.

And, the illuminance before 5 cm of the electrodes facing each other in the axial direction 1 cm from the position 5 cm from the tip of the electrode is measured by an illuminance meter, and as shown in FIG. The average value is used to observe the degree of deviation between the average value and each illuminance (that is, uneven illuminance).

The observed results are summarized in Table 1. In Table 1, when there is a maximum deviation of 15% or more from the average value, it is marked as ×, when the maximum deviation is between 10% and 15%, it is defined as △, and when the maximum deviation is between 5% and 10%, it is marked as ○, On the other hand, when the degree of deviation is less than 5% at the maximum, it is regarded as ◎.

Table 1

(Description of symbols) ◎: Large effect ○: Effective △: Some effect ×: Almost no effect

As shown in Table 1, when the low frequency f2 is 30% or less of the stable lighting frequency f1, the effect of suppressing the unevenness of illuminance can be obtained.

However, when the low frequency f2 is 3 Hz, electrode deformation occurs. This is because the period in which the current flows from one electrode to the other electrode is too long, that is, the DC lighting period is too long, and the electrodes collided by electrons may be deformed on one side. Therefore, the preferred range of the low frequency f2 is 5≤f2≤0.3f1.

In addition, in Table 1, when the stable lighting frequency f1 is 1000 Hz, all are Δ, and in this case, when the stable lighting frequency f1 is in the range of 800 Hz or less, it shows that the illuminance unevenness is suppressed. This is, f1: the range below 800 Hz is equivalent to f1 < (Hg/30) ^-0.33 × 250/AL in the formula (4) used in the above-mentioned condition for suppressing acoustic resonance, so it can be seen that the use of acoustic resonance can be suppressed. Resonance made by uneven illumination.

(2) Experimental example 2

The experiment was carried out under the same conditions as in Experimental Example 1 above, changing the light emitting length of the lamp (distance between electrodes) to 1000 mm. Lamp specifications are described below.

Discharge tube (light-emitting tube): inner diameter 5.4mm outer diameter 9mm

Outer tube: inner diameter 9.15mm outer diameter 12mm

Lighting length (distance between electrodes): 1000mm

·Enclosure

Mercury density 5mg/cm ³

The flow rate of cooling water flowing between the water cooling jacket and the outer pipe: 25L/min

The results are shown in Table 2.

In this case, the frequency f1 is between 400 Hz and 500 Hz, and it can be seen that the suppression of unevenness in illuminance by acoustic resonance is effective.

Table 2

(Description of symbols) ◎: Large effect ○: Effective △: Some effect ×: Almost no effect

(3) Experimental example 3

The same experiment was performed under the same conditions as in Experimental Example 1 above, using a metal halide lamp with the lamp enclosure changed. Lamp specifications are described below.

Discharge tube (light-emitting tube): inner diameter 4.6mm outer diameter 10.3mm

Outer tube: inner diameter 10.45mm outer diameter 13mm

Lighting length (distance between electrodes): 500mm

·Enclosure

Mercury density 2.5mg/cm ³

Iron iodide: 0.45mg/ ^cm3

Passive iodide: 0.06mg/cm ³

The flow rate of cooling water flowing between the water cooling jacket and the outer pipe: 20L/min

The results are shown in Table 3.

table 3

(Description of symbols) ◎: Large effect ○: Effective △: Some effect ×: Almost no effect

In this case, the frequency f1 is between 1000 Hz and 1200 Hz, and it can be seen that the suppression of unevenness in illuminance by acoustic resonance is effective. That is, compared with the added amount of metals other than mercury, if the added amount of mercury is large (about 5 times more than other metals), it can be seen that f1<(Hg/30) ^-0.33 × 250/AL.

In addition, from the experimental results of (2)-(3) above, it was confirmed that the expression 5≤f2≤0.3f1 in the preferred range of low frequency f2 obtained in Experimental Example 1 can also be applied to other lamps.

Claims (4)

1. ignition device comprises:

High-pressure discharge lamp, it is sealed to possess two ends, disposes pair of electrodes relatively in inside, and inclosure has all of metal formation to be bar-shaped discharge tube at least, and is located at the outer tube of the foreign side of this discharge tube;

Stream forms member, extend ground along the tubular axis of above-mentioned high-pressure discharge lamp and be provided with, and the outer tube of high-pressure discharge lamp between form the stream that cooling water flow through; And

Power supply is electrically connected on this pair of electrodes and to the power supply of above-mentioned high-pressure discharge lamp,

It is characterized by:

Above-mentioned power supply comprises:

Signal generates mechanism, generates to have the 1st signal that is used for the point of safes modulation frequency f1 of above-mentioned high voltage discharge lamp lighting, and has the 2nd signal of the even frequency f 2 lower than this point of safes modulation frequency f1 of the uneven illumination that is used to solve above-mentioned high-pressure discharge lamp;

Above-mentioned the 1st signal or the 2nd signal are optionally exported in switching mechanism; And

Phase inverter drives by above-mentioned the 1st signal or the 2nd signal, and the alternating voltage of frequency f 1 or frequency f 2 is supplied in above-mentioned high-pressure discharge lamp.

2. ignition device as claimed in claim 1,

Above-mentioned switching mechanism has timing mechanism, by this timing mechanism, the alternating voltage of frequency f 1 is supplied in discharge lamp to begin after the 1st scheduled time, the frequency that will be supplied in the alternating voltage of above-mentioned high-pressure discharge lamp is reduced to f2 from f1, and during the 2nd scheduled time alternating voltage of said frequencies f2 is supplied in above-mentioned high-pressure discharge lamp.

3. ignition device as claimed in claim 1 or 2, wherein,

The aforementioned stable frequency f 1[Hz that lights a lamp] with frequency f 2[Hz] relation, be f2≤0.3f1.

4. as each described ignition device in the claim 1 to 3,

The metal that is enclosed in the above-mentioned discharge tube contains mercury,

The aforementioned stable frequency f 1[Hz that lights a lamp], will be enclosed in the mercury density [mg/cm of discharge tube ³] as Hg, and with interelectrode distance [m] during as AL, then

f1＜(Hg/30) ^-0.33×250/AL。

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