JP2005285544A - Optical instrument and high-pressure discharge lamp used for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a start-up property of a high-pressure discharge lamp with mercury and halogen sealed in, enable to start up lighting of a lamp without failure at low voltage, and further, aim at downsizing and cost reduction of an optical device using a lamp of this kind. <P>SOLUTION: The optical device removes residual impurity gas in a discharge vessel (7) that can be an inducer of halogen gasification to an extent of H<SB>F</SB>/H<SB>T</SB>≤0.15, provided a total halogen amount sealed in the discharge vessel of the high-pressure discharge lamp (2) is H<SB>T</SB>(mol), and a gasified halogen amount in the discharge vessel at a light-off ambient temperature, and at the same time, at an outer surface of the sealing part of one electrode whose temperature first falls below liquefied temperature of mercury after lighting off of the lamp out of a pair of electrodes (9A, 9B) of the discharge lamp (2), a trigger wire (13) is wound around connected to the electrode opposing it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical device including a high-pressure discharge lamp that emits light by discharge in mercury vapor, and the high-pressure discharge lamp.

  As a backlight light source used in a liquid crystal projector, a projection type liquid crystal display device, etc., it is required to project an image uniformly with sufficient brightness, efficiency and color rendering on a screen. A high-pressure discharge lamp called a metal halide lamp in which mercury or a metal halide is enclosed in a discharge vessel in which the lamps are opposed to each other is used.

And, in recent years, since it is required to further miniaturize-point source of light sources, instead of a high pressure discharge lamp filled with metal halide, with 0.2 mg / mm ³ of mercury in the discharge vessel CH A high pressure discharge lamp called an ultrahigh pressure mercury lamp in which a halogenated gas such as ₂ Br ₂ is enclosed and the mercury vapor pressure in a stable lighting state of the lamp exceeds 200 atm has been proposed.
In this type of lamp, the mercury vapor pressure in the discharge vessel in a stable lighting state is set to an extremely high pressure, thereby suppressing the radial expansion of the discharge arc generated between the electrodes and improving the light output. Realizes high efficiency and high color rendering.
JP-A-2-148561 JP-A-6-52830 JP 2000-515311 A

When the high-pressure discharge lamp as described above is used as the light source device of the liquid crystal projector, the high-pressure discharge lamp is arranged on the optical axis of the reflecting mirror to assemble the high-pressure discharge lamp unit and connect it to the lamp lighting device.
In this case, the lamp lighting device is provided with a starting circuit called an igniter, and a breakdown voltage is generated between both electrodes by applying a starting voltage of 15 kV or more as a pulse voltage when starting the lamp lighting, and then the discharge is maintained. Current is supplied, leading to a stable lighting state.

  By the way, along with the downsizing and low price of liquid crystal projectors, there is a strong demand for downsizing and low price of the light source device. For the purpose of lowering the price, there has been a demand for a design change such as changing the circuit components of the lighting circuit to a material with a low withstand voltage or reducing the conventionally applied starting voltage of 15 kV or more to 10 kV or even 5 kV or less.

  For this reason, first, when a starting test of the lamp was performed by applying a starting voltage of 10 kV between the electrodes, a starting failure frequently occurred. Therefore, a similar experiment was conducted on a high-pressure discharge lamp provided with a trigger wire, which is a starting improvement means employed in a metal halide lamp used in a conventional liquid crystal projector.

A high pressure discharge lamp device (optical device) 21 shown in FIG. 5 includes a high pressure discharge lamp 22, a reflecting mirror 23, and a lighting device 24 including an electronic ballast.
As shown in FIG. 6, the high-pressure discharge lamp 22 has a pair of electrodes 25A and 25B. The electrodes are molybdenum embedded in sealing portions 27A and 27B that hermetically seal both ends of the discharge vessel 26. The power supply lead wires 29A and 29B are connected to the power supply lead wires 29A and 29B via the foils 28A and 28B, respectively, and lamp power is supplied from the lighting device 24 through the lead wires 29A and 29B.
Further, the trigger wire 30 connected to the lead wire 29B of the electrode 25B on the opening side of the reflecting mirror 23 is wound around the discharge vessel 26 on the outer surface of the sealing portion 27A in the vicinity of the electrode 25A on the bottom side of the reflecting mirror 23, The trigger wire 30 is maintained at the same potential as the electrode 25B.

  In the high-pressure discharge lamp device 21 configured as described above, when a starting voltage is applied, the electrode 25A becomes very easy to emit electrons due to the effect of the trigger wire 30, and as a result, between the electrodes 25A and 25B. It is thought that dielectric breakdown is likely to occur.

However, even when the high-pressure discharge lamp device 21 provided with the trigger wire 30 is used as described above, a starting failure occurs when the starting voltage is lowered to 10 kV.
Further, when the experiment was repeated, the cause of the start failure was not only due to the low start voltage, but also halides such as CH ₂ Br ₂ enclosed in the arc tube and other O ₂ , H ₂ , CO, Impurity gas such as H ₂ O inhibits the dielectric breakdown between the electrodes at the time of starting the lamp, and the effect of the trigger wire can be sufficiently obtained by adhering a large amount of mercury in the discharge vessel to the electrode. The conclusion was not reached.
Therefore, the halogen content of the high-pressure discharge lamp used for the lighting test was measured.

The amount of halogen (bromine) was measured using a general ion chromatograph. As described above, gasified halogen and solid halogen generated when the lamp was turned off were measured.
First, in order to measure the amount of solid halogen, after turning off the light-emitting tube at room temperature and letting out the gasified halogen, the arc tube is dissolved in an eluent that dissolves the halogen (mixed aqueous sodium bicarbonate and sodium carbonate). In this method, the halogen remaining in the solid state is dissolved in the eluent, and the amount of the halogen (bromine) is measured.

By this method, gasified halogen present in the arc tube when the arc tube is crushed is removed, and only solid halogen can be measured. The amount of gasified halogen present can be calculated.
Next, the total amount of halogen sealed in the arc tube was calculated from the average value of all the halogens dissolved in the eluent by pulverizing the arc tube of the same specification in the eluent.
The gasified halogen amount can be determined from these differences.

  Then, when the lamp used in the start test was measured by the above method, the gasified halogen amount of the lamp having good startability was 15% or less of the total halogen content, but a start failure was caused. It was found that the gasified halogen content of the lamp exceeded 15% of the total halogen content enclosed.

From the above, the halide sealed in the arc tube is decomposed while the lamp is turned on. However, when the lamp is turned off and the room temperature is reached, many of them are called solid state halogens such as HgBr ₂ (hereinafter referred to as “solid halogen”). ) Is generated.
However, depending on the lamp, a gaseous halogen such as CH ₂ Br ₂ or HBr (hereinafter referred to as “gasified halogen”) is also generated.
Since gasified halogen has a strong electron affinity, if the proportion of gasified halogen present at room temperature is extinguished, electrons released from the electrode are adsorbed by the gasified halogen due to the starting voltage applied when starting the lamp. It is considered that starting failure occurs due to insufficient electrons contributing to dielectric breakdown.

And even if it is a high-pressure discharge lamp of the same specification with the same filling material composition in the arc tube, the ratio of the gasified halogen amount in the normal temperature state is different for each lamp. As a result, it has been found that when an impurity gas such as H ₂ O or CO that is combined with halogen and gasifies the halogen at room temperature remains in the arc tube, gasified halogen is easily generated. .

  Further, when the adhesion state of mercury was observed, a large amount of mercury adhered to the electrode 25B on the reflection mirror front opening side rather than the electrode 25A on the reflection mirror bottom side, and the mercury adhered even when a starting voltage was applied. Since the electron emission from the electrode 25B is hindered by mercury, the dielectric breakdown necessary for starting the lamp is not reached, which causes a starting failure.

  The present invention has been made on the basis of the inventor's knowledge as described above, and can improve the startability of a high-pressure discharge lamp in which mercury and halogen are sealed, so that the lamp can be started to start at a low voltage without malfunction. As a result, it is a technical problem to reduce the size and cost of an optical device using this type of lamp.

In order to solve this problem, according to the first aspect of the present invention, a pair of electrodes are disposed opposite to each other in a discharge vessel having sealing portions formed at both ends, and at least halogen, mercury, and a rare gas are enclosed. and a high-pressure discharge lamp, the optical device having a reflector which arranged the lamp on the optical axis, the high-pressure discharge lamp, a halogen amount sealed in the discharge vessel and H _{T (mol),} in off normal temperature When the amount of halogenated gas in the discharge vessel is H _F (mol),
H _F / H _T ≦ 0.15
The residual impurity gas in the discharge vessel, which becomes a halogen gasification inducing factor, is removed to the extent that the electrode is sealed, and the electrode side seal of the pair of electrodes that first falls below the mercury liquefaction temperature after the lamp is extinguished. A trigger wire connected to an electrode facing the stop portion is wound around the outer surface of the stop portion.

According to the present invention, since residual impurity gases such as O ₂ , H ₂ , H ₂ O, and CO, which are halogen gasification inducers in the arc tube, are removed, the gasified halogen in the normal temperature state of turning off the high-pressure discharge lamp. The amount can be suppressed to 15% or less of the total halogen amount.
That is, electrons emitted from the electrode by the starting voltage applied as a pulse voltage at the time of starting the lamp contribute to dielectric breakdown without being adsorbed by the gasified halogen, and the starting performance of the lamp is improved. Even if the engine speed is lowered, the occurrence of starting failure is reduced.

Further, in the case of a high-pressure discharge lamp in which a large amount of mercury adheres to the electrode on the reflecting mirror opening side, the electrode is lowered to the mercury liquefaction temperature or lower before the electrode on the bottom side of the reflecting mirror.
Therefore, if the trigger wire connected to the electrode facing this is wound around the outer surface of the sealing portion of the electrode on the reflector opening side, sufficient electron emission can be obtained from the electrode to which mercury has adhered, Since dielectric breakdown easily occurs, even if the starting voltage is lowered, the occurrence of starting failure is reduced.

  In this example, the startability of the high-pressure discharge lamp is improved so that the lamp can be started with no trouble at a low voltage. As a result, an optical device using this type of lamp is reduced in size and price. This problem was realized by controlling the amount of gasified halogen in the lamp arc tube and by changing the position of the trigger wire and the connection electrode.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is an explanatory view showing an optical device according to the present invention, FIG. 2 is an enlarged view showing a high-pressure discharge lamp,
FIG. 3 is an explanatory view showing the manufacturing process, and FIG. 4 is an explanatory view showing another embodiment of the high-pressure discharge lamp.

  FIG. 1 shows an optical device 1 used as a light source device for a liquid crystal projector, and a lamp unit 4 having a high-pressure discharge lamp 2 such as an ultra-high pressure mercury lamp arranged on the optical axis of a reflecting mirror 3 supplies an AC rectangular wave current. A cooling fan (cooling mechanism) 6 for cooling the discharge lamp 2 from the front opening side of the reflecting mirror 3 is provided while being connected to the lighting device 5 including an electronic ballast.

As shown in FIG. 2, the high-pressure discharge lamp 2 is formed in a discharge vessel 8 having a maximum outer diameter of about 10 mm, a maximum inner diameter of about 4.5 mm, and an internal volume of about 60 mm ³ formed in the central portion of an arc tube 7 made of quartz glass. In addition, a pair of electrodes 9A and 9B are arranged to face each other at a distance of 1.0 mm, mercury is about 0.18 mg / mm ³ , and a starter gas rare gas (argon) is about 20 kPa (at room temperature). ) And 1.0 × 10 ⁻² μmol of halogen to prevent blackening is enclosed and designed to have a rating of 150 W.
In addition, since noble gas as auxiliary gas for start-up becomes higher than 20 kPa at room temperature, startability is deteriorated. The range is set.

The high-pressure discharge lamp 2 has a total halogen content enclosed in the discharge vessel 8 as H _T (mol) and a gasified halogen amount in the discharge vessel 7 in the extinguishing room temperature state as H _F (mol).
H _F / H _T ≦ 0.15
As a result, residual impurity gas in the discharge vessel, which becomes a halogen gasification-inducing factor, is removed, so that the amount of gasified halogen can be suppressed to 15% or less even when the lamp 2 is turned off and at room temperature.

Each electrode 9A, 9B is connected to power supply lead wires 12A, 12B via molybdenum foils 11A, 11B embedded in sealing portions 10A, 10B that hermetically seal both ends of the discharge vessel 7, Lamp power is supplied from the lighting device 5 through the lead wires 12A and 12B.
Further, of the pair of electrodes 9A and 9B, the trigger wire 13 is wound around the outer surface of the sealing portion 10B that supports the reflecting mirror 3 opening side electrode 9B whose electrode temperature first falls below the mercury liquefaction temperature after the lamp is extinguished. The trigger wire 13 is electrically connected to the electrode 9A on the bottom side of the reflecting mirror 3 via the lead wire 12B and is maintained at the same potential as the electrode 9A.

FIG. 3 shows a manufacturing procedure of the high-pressure discharge lamp 2.
First, the arc tube material and the metal material to be an electrode are each vacuum heat treated to remove impurities in advance, and a quartz glass arc tube 7 having a pair of insertion ports 7A and 7B formed at both ends is used. One electrode 9A is fixed to the sealing portion 10A by inserting an electrode mount through the insertion port 7A and hermetically sealing the insertion port 7A (FIG. 3A).

Next, before introducing mercury or the like from the other insertion port 7B that is open, a vacuum heat treatment is again performed at 1000 ° C. for 5 hours to remove substances that become residual impurity gases (FIG. 3B). ).
Further, after introducing mercury, a rare gas, and a halogen from the other insertion port 7B (FIG. 3C), an electrode mount is inserted to hermetically seal the opening 7B, thereby sealing the sealing portion 10B. A lamp is manufactured through a process of fixing the other electrode 9B (FIG. 3D).
Note that the manufacturing procedure of the high-pressure discharge lamp 2 is not limited to the above, and it is only necessary that the residual impurity gas is removed as a result.

When the high-pressure discharge lamp 2 manufactured in this way is fixed to the mounting hole 14 formed at the center of the bottom of the reflecting mirror 3, the outer surface of the sealing portion 10B that supports the electrode 9B on the opening side of the reflecting mirror 3 Since the trigger wire 13 is wound around and the trigger wire 13 is electrically connected to the electrode 9A on the bottom side of the reflecting mirror 3, the trigger wire 13 and the electrode 9A are maintained at the same potential.
In this case, the trigger wire 13 is provided on the outer surface of the sealing portion that supports the electrode on the side of the pair of electrodes 9A and 9B whose electrode temperature first falls below the mercury liquefaction temperature after the lamp is extinguished.
The “electrode that first falls below the mercury liquefaction temperature” refers to the operating temperature when the high-pressure discharge lamp 2 is lit, the thermodynamic characteristics such as the heat capacity and thermal conductivity of the high-pressure discharge lamp 2 and the reflector 3 on which it is mounted, cooling As determined by the cooling characteristics of the fan 6, the high-pressure discharge lamp of the same specification without the trigger wire 13 is subjected to a lighting experiment under the same conditions, so that the electrode to which a large amount of mercury adheres is “lower than the mercury liquefaction temperature first”. It may be an “electrode”.

  Using the high pressure discharge lamp 2 of this example manufactured in this way and the high pressure discharge lamp manufactured without vacuum heat treatment for removing the substance that becomes the residual impurity gas as a comparative example, the lighting device 5 leads the lead wire 12A. , The lighting test to apply the starting voltage to 12B, and after lighting for 20 minutes so as to be in a stable lighting state, the lamp 2 is turned off, the lamp is cooled by the lamp cooling fan 6 for about 2 minutes, and then started again A relighting test is performed in which voltage is applied to attempt lighting, and the ratio of the number of lit lamps is shown as a lighting rate, and the ratio of the number of unlit lamps is shown in Table 1.

When the potential difference of the starting voltage is 10 kV (± 5 kV) and 6 kV (± 3 kV), the lamp of this example in which the substance that becomes the residual impure gas is removed by the vacuum heat treatment is used in both the lighting test and the re-lighting test. It was 0% (lighting rate 100%).
On the other hand, the lamp of the comparative example in which the substance that becomes the residual impure gas was not removed had a non-lighting rate of 0% in the lighting test with a starting voltage potential difference of 10 kV (± 5 kV), but the non-lighting rate in the re-lighting test. When the potential difference of the starting voltage was lowered to 6 kV (± 3 kV), the non-lighting rate reached 10% in the lighting test and the non-lighting rate reached 65% in the re-lighting test.

  Next, with respect to the presence or absence of non-lighting when the starting voltage applied to the electrodes 9A and 9B of the high-pressure discharge lamp 2 of this example is changed and turned on after setting the potential difference between the electrodes of the starting voltage to 6 kV and 4 kV. Experiments were performed and the results are shown in Table 2.

As shown in Table 2, when the potential difference of the starting voltage applied between the electrodes 9A and 9B was 6 kV, nothing was not turned on, but when the potential difference was reduced to 4 kV, the trigger line 13 When the electrode 9A connected to is at zero potential (No. 9, No. 10), there was a case where non-lighting occurred.
Thus, in order to reduce the lighting failure even when the starting voltage is lowered, it is preferable not to set the electrode 9A connected to the trigger line 13 to 0 potential regardless of the polarity of the electrodes 9A and 9B and the polarity of the starting voltage. .

The present invention is not limited to an optical device used as a light source device of a liquid crystal projector and a high-pressure discharge lamp used therein, but is also a general lighting device, an industrial lighting device used in a semiconductor manufacturing process, and other optical devices. The present invention can also be applied to the apparatus and the high-pressure discharge lamp used in the apparatus.
In addition, the trigger wire 13 is not limited to the case where the trigger wire 13 is wound around the outer surface of the sealing portion as shown in FIG. It may be simply wound in a shape, and the startability improvement is not affected by the winding method.

  As described above, according to the present invention, even when the starting voltage applied between the electrodes is lowered when starting the lighting of the lamp, the lighting start can be surely performed without any trouble, so that the high pressure discharge lamp 2 and the lighting device 5 can be started. There is a very excellent effect that can be reduced in size and price.

  The present invention is suitable for use in a light source device for a backlight such as a liquid crystal projector that is required to be reduced in size and price.

Explanatory drawing which shows the optical apparatus which concerns on this invention. Explanatory drawing which shows the high pressure discharge lamp which concerns on this invention. Explanatory drawing which shows the example of a manufacture procedure of a high pressure discharge lamp. Explanatory drawing which shows other embodiment of a high pressure discharge lamp. Explanatory drawing which shows the conventional optical apparatus. Explanatory drawing which shows the conventional high pressure discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical apparatus 2 High pressure discharge lamp 3 Reflector 5 Lighting apparatus 6 Cooling fan (cooling mechanism)
8 Discharge vessel 9A, 9B Electrode 10A, 10B Sealing part 13 Trigger wire

Claims (7)

A pair of electrodes are arranged opposite to each other in a discharge vessel having sealing portions formed at both ends, and a high-pressure discharge lamp in which at least halogen, mercury, and a rare gas are sealed, and the lamp is disposed on the optical axis. In an optical device with a reflector,
In the high-pressure discharge lamp, when the total halogen amount enclosed in the discharge vessel is H _T (mol) and the gasified halogen amount in the discharge vessel in the extinguishing room temperature state is H _F (mol),
H _F / H _T ≦ 0.15
To the extent that the residual impurity gas in the discharge vessel, which becomes a halogen gasification inducing factor, is removed,
Of the pair of electrodes, after the lamp is extinguished, the trigger wire connected to the electrode facing this is wound around the outer surface of the sealing part on the electrode side where the electrode temperature first falls below the mercury liquefaction temperature. Optical device characterized. A high-pressure discharge lamp in which at least halogen, mercury, and a rare gas are sealed is disposed on the optical axis of the reflecting mirror while a pair of electrodes are arranged to face each other in a discharge vessel having sealing portions formed at both ends. In an optical device,
In the high-pressure discharge lamp, when the total halogen amount enclosed in the discharge vessel is H _T (mol) and the gasified halogen amount in the discharge vessel in the extinguishing room temperature state is H _F (mol),
H _F / H _T ≦ 0.15
An optical device characterized in that the residual impurity gas in the discharge vessel, which becomes a halogen gasification inducing factor, is removed. A high-pressure discharge lamp in which at least halogen, mercury, and a rare gas are sealed is disposed on the optical axis of the reflecting mirror while a pair of electrodes are arranged to face each other in a discharge vessel having sealing portions formed at both ends. In an optical device,
Of the pair of electrodes, after the lamp is extinguished, the trigger wire connected to the electrode facing this is wound around the outer surface of the sealing part on the electrode side where the electrode temperature first falls below the mercury liquefaction temperature. Optical device characterized.   The optical apparatus according to claim 1, further comprising a cooling mechanism that cools the high-pressure discharge lamp until the temperature is lowered to a predetermined temperature after the lamp is turned off or for a predetermined time.   The optical device according to claim 1, further comprising a lighting device that applies a starting voltage to the electrode side to which the trigger wire is connected. In a high-pressure discharge lamp in which a pair of electrodes are arranged opposite to each other in a discharge vessel in which sealing portions are formed at both ends, and at least halogen, mercury, and a rare gas are enclosed,
When the total amount of halogen enclosed in the discharge vessel is H _T (mol) and the amount of gasified halogen in the discharge vessel in the extinguishing room temperature state is H _F (mol),
H _F / H _T ≦ 0.15
The high-pressure discharge lamp is characterized in that residual impurity gas in the discharge vessel, which becomes a halogen gasification inducing factor, is removed to such an extent that The high-pressure discharge lamp according to claim 6, wherein the residual impure gas is O ₂ , H ₂ , H ₂ O and CO.

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