JP2009004203A - Super high pressure mercury lamp - Google Patents

Abstract

An ultra-high pressure mercury lamp capable of solving both the flicker phenomenon and the shape deformation of the cathode tip in both the defuse mode and spot mode lighting state.
An anode and a cathode are arranged opposite to each other, a light emitting portion in which mercury of 0.15 mg / mm ³ or more is enclosed, a light emitting tube including a pair of sealing portions, and embedded in each of the sealing portions. And a cathode shaft portion connected to the tip side of the metal foil, and the cathode connected to the metal foil and projecting outward from the sealing portion. An ultra-high pressure mercury lamp that includes a cathode tip that is formed continuously from the shaft and gradually narrows toward the tip, wherein the cathode has an outer diameter of the tip of the cathode tip as D1. When the outer diameter of the base end portion of the portion is D2, the taper angle is θ, and the current value to be input is I, the relationship shown in the following formula 1 is satisfied. (Formula 1) 0.332 ≦ I ² /(D1×D2×θ)≦2.904
[Selection] Figure 2

Description

  The present invention relates to a DC lighting ultra-high pressure mercury lamp used as a light source for a projection projector apparatus such as a liquid crystal projector or a DLP (digital light processor) using a DMD (digital micromirror device).

As a light source for projection projector devices such as liquid crystal projectors and DLP using DMD, an ultra-high pressure mercury lamp with a mercury vapor pressure of 150 atm or higher is used instead of a conventional halogen lamp or metal halide lamp. The use is becoming mainstream. An ultra-high pressure mercury lamp has an arc tube in which a pair of rod-shaped sealing parts are continuously formed at both ends of a substantially spherical light emitting part, and discharge is performed in a sealed space formed inside the light emitting part. The anode and cathode for use are spaced apart by a distance of 3.0 mm or less, and 0.15 mg / mm ³ or more of mercury is enclosed.

In recent ultra-high pressure mercury lamps, since the total length of the arc generated between the electrodes during lighting is required to be 2 mm or less, the amount of mercury enclosed in the light emitting part is increasing. Is filled with 0.2 mg / mm ³ or more of mercury in the light emitting portion. In ultra-high pressure mercury lamps that contain a large amount of mercury, the tip of the cathode is made narrower because the arc between the electrodes shrinks due to the high pressure inside the light emitting part when it is lit. The part is processed so as to have a certain area, and the arc is prevented from moving on the tip surface of the cathode by generating an arc from the entire tip surface (arc generating surface) of the cathode. Thus, the lighting state in which an arc is generated from the entire arc generation surface is referred to as a defuse mode.

  In addition, there is an increasing demand for projection type projector devices to perform so-called energy-saving lighting in which an ultra-high pressure mercury lamp is lit with input power lower than rated lighting power for the purpose of reducing power consumption. However, when the ultra-high pressure mercury lamp is turned on with a power lower than the rated power, the arc cannot be generated from the entire arc generation surface, and the arc is generated from only a part of the arc generation surface. As a result of the arc repeatedly moving on the arc generation surface, a so-called flicker phenomenon occurs that causes flickering in the image projected on the screen. In this way, a state where an arc is generated from only a part of the arc generation surface is referred to as a spot mode.

  In order to suppress the occurrence of the flicker phenomenon at the time of energy saving lighting, in order to realize the lighting state in the above-described defuse mode, it is necessary to further reduce the cathode tip in order to generate an arc from the entire arc generating surface of the cathode. Conceivable. However, if the cathode tip is made extremely thin, even if the occurrence of flicker phenomenon can be suppressed, the heat capacity of the cathode tip becomes small and the cathode tip melts and evaporates and the shape is likely to deform. As the discharge distance between the electrodes set in the initial stage increases, the amount of light that can be used in combination with the reflector is extremely reduced, resulting in a short life.

As described above, according to the defuse mode, there is a problem that the shape of the cathode tip is easily deformed while the flicker phenomenon is difficult to occur, and according to the spot mode, the arc is generated on the arc generation surface. Since it is only a part, the shape of the cathode tip is difficult to deform, but there is a problem that a flicker phenomenon is likely to occur. Therefore, in the projector apparatus adopting the energy saving lighting method, it is difficult to solve both the flicker phenomenon and the shape deformation of the cathode tip.
Japanese Patent Laid-Open No. 2-148561

  An object of the present invention is to provide an ultra-high pressure mercury lamp that can solve both the flicker phenomenon and the shape deformation of the cathode tip in both the defuse mode and the spot mode.

The ultra-high pressure mercury lamp of the present invention has a light emitting part in which an anode and a cathode are arranged facing each other and 0.15 mg / mm ³ or more of mercury is enclosed, and both ends of the light emitting part are continuous. An arc tube comprising a pair of sealing portions formed to extend along the tube axis, a pair of metal foils embedded in each of the pair of sealing portions and extending along the tube axis, and the pair of pairs A pair of external leads extending along the tube axis so that the distal end side is connected to each of the metal foils and the proximal end side protrudes outward from the outer end surface of the sealing portion;
The cathode extends along the tube axis, and the base end side is embedded in the sealing portion and is connected to the tip end side of the metal foil, and is continuously formed on the tip end side of the cathode shaft portion. In the ultra-high pressure mercury lamp provided with the cathode cusp gradually narrowing toward the tip side,
The cathode is charged with the outer diameter of the distal end of the cathode apex being D1, the outer diameter of the base end of the cathode apex being D2, and the taper angle of the cathode apex being θ. When the current value is I, the relationship shown in the following formula 1 is satisfied.
(Formula 1) 0.332 ≦ I ² /(D1×D2×θ)≦2.904

  Furthermore, the cathode of the ultrahigh pressure mercury lamp of the present invention is characterized in that the cathode shaft portion and the cathode tip are made of tungsten having a purity of 99.9% or more.

According to the super high pressure mercury lamp of the present invention, the cathode having the cathode tip gradually narrowing toward the tip side is provided, the outer diameter of the tip of the cathode tip is D1, and the cathode tip. 0.32 ≦ I ² / (D1 × D2 × θ) ≦ 2 where D2 is the outer diameter of the base end of the portion, θ is the taper angle of the cathode tip, and I is the input current value. .904 satisfying the relationship. As a result, the arc generation surface of the cathode apex is adjusted to an appropriate size, so that even if it is lit in the spot mode, the occurrence of the flicker phenomenon can be suppressed to such an extent that it does not cause a problem in practice. Even when the fuse is lit in the defuse mode, it is possible to suppress the cathode peak from becoming extremely hot and prevent the shape of the cathode peak from being deformed.

  FIG. 1 is a cross-sectional view in the tube axis direction showing an outline of the configuration of the extra-high pressure mercury lamp of the present invention. FIG. 2 is an enlarged view showing the configuration of the electrodes of the ultrahigh pressure mercury lamp shown in FIG.

  As shown in FIG. 1, the ultra-high pressure mercury lamp 100 is made of a material that transmits visible light, such as quartz glass, for example, and has a substantially spherical light emitting part 11 located at the center in the tube axis direction, and is continuous to both ends of the light emitting part 11. A pair of rod-shaped sealing portions 12a and 12b is provided with the arc tube 1 configured to extend in the tube axis direction. Inside the light emitting unit 11, an anode 2 and a cathode 3 made of tungsten or the like are arranged facing each other with a distance of 0.5 to 2.0 mm. Thin metal foils 4a and 4b made of a conductive material such as molybdenum are embedded in each sealing portion 12a and 12b in an airtight manner by shrink sealing. Each of the pair of external leads 5a and 5b extending along the tube axis has its distal end side joined to the proximal end side of each metal foil 4a and 4b by, for example, spot welding, and its proximal end side has each sealing portion 12a and 12b. Projecting outward of the sealing portions 12a and 12b.

Mercury, rare gas, and halogen gas are sealed inside the light emitting unit 11. For example, in order to obtain visible light of 360 to 780 nm, for example, mercury is enclosed in 0.15 mg / mm ³ , for example, so that the mercury vapor pressure in the light-emitting unit 11 is 150 atm or more during lighting. Since the amount of mercury enclosed increases as the amount of mercury enclosed increases, it is preferably 0.2 mg / mm ³ or more.

The rare gas is filled with, for example, 13 kPa of argon gas in order to improve the lighting startability. The halogen gas is enclosed in order to extend the life of the lamp by utilizing the halogen cycle and prevent the light emitting unit 11 from being damaged and devitrified, and the amount enclosed is in the range of 10 ⁻⁶ to 10 ⁻² μmol / mm ³ . To be adjusted appropriately according to the lamp specifications. The anode 2 by amount of halogen gas and ^10-6 above, it is possible to avoid breakage or devitrification of the light emitting unit 11 as well as transport of tungsten constituting the cathode 3, the amount of halogen gas 10 ^{- By} setting it to ² or less, it is possible to prevent the arc from fluctuating due to the convection of the halogen gas in the light emitting unit 11.

  The anode 2 has a rod-shaped anode shaft portion 21, a truncated cone-shaped root portion 22 a that is formed continuously with the tip end side of the anode shaft portion 21 and gradually increases toward the tip end side, and on the tip end side of the root portion 22 a. A continuous column-shaped intermediate portion 22b, and an anode main body portion 22 formed of a truncated cone-shaped tip portion 22c that gradually decreases toward the tip side continuously with the intermediate portion 22b. In the anode 2, the base end portion of the anode shaft portion 21 is connected to the tip portion of the metal foil 4 b in a state where the center axis of the anode shaft portion 21 coincides with the center axis of the arc tube 1, and the tip end of the anode shaft portion 21. A part on the side and the whole anode main body portion 22 are arranged so as to protrude into the sealed space in the light emitting portion 11. In such an anode 2, the anode shaft portion 21 and the anode main body portion 22 are physically integrally formed by cutting a tungsten rod.

  The cathode 3 includes a rod-shaped cathode shaft portion 31, a truncated cone-shaped cathode tip 32 that is formed continuously from the cathode shaft portion 31 toward the distal end side and gradually increases toward the distal end side, and a cathode shaft portion 31. And a coil portion 33 provided in the vicinity of the boundary portion between the cathode tip portion 32 and closer to the base end side of the cathode shaft portion 31 than the boundary portion. The base end portion of the cathode shaft portion 31 is connected to the tip portion of the metal foil 4a in a state where the cathode 3 and the cathode shaft portion 31 coincide with the central axis of the arc tube 1, and a part of the cathode shaft portion 31 on the tip side. The whole of the cathode apex 32 and the whole of the coil part 33 are arranged so as to be exposed to the sealed space in the light emitting part 11. In such a cathode 3, the cathode shaft portion 31 and the cathode peak portion 32 are physically integrally formed by cutting a tungsten rod.

  The coil portion 33 is formed by winding a wire made of tungsten around the cathode shaft portion 31 in a coil shape. Since the startability of the ultrahigh pressure mercury lamp 100 is improved by providing the coil portion 33, it is not necessary for the cathode 3 to contain an easy electron emitting material, and the easy electron emitting material evaporated when the lamp is lit up By adhering to the inner wall, there is no possibility that the output of the light emitted from the light emitting unit 11 is reduced.

  The anode shaft portion 21, the anode main body portion 22, the cathode shaft portion 31, the coil portion 33, and the cathode tip 32 protruding to the inside of the light emitting portion 11 are all made of tungsten having a purity of 99.9% or more. Therefore, impurities are not scattered in the light emitting unit 11 and the light emitting unit 11 is not contaminated by the impurities.

In the ultra high pressure mercury lamp 100 described above, even if the ultra high pressure mercury lamp is lit in either the spot mode or the defuse mode, the occurrence of flicker phenomenon and the shape deformation of the cathode tip 32 are suppressed. The relationship between the outer diameter of the tip of the cathode cusp 32, the outer diameter of the base of the cathode cusp 32, the taper angle of the truncated cone 32 having a truncated cone shape, and the input current is adjusted. .
That is, as shown in FIG. 2, in the cross section including the central axis C of the cathode 3, when the tip 32a of the cathode cusp 32 is sandwiched between two parallel lines, the interval between the parallel lines is maximized. The diameter D1 (mm) is defined as “the outer diameter of the tip of the cathode peak”, and the base end 32b of the cathode peak 32, that is, two boundaries between the cathode peak 32 and the cathode shaft 31 are provided. , The outer diameter D2 (mm) at which the interval between the parallel lines is the maximum is “the outer diameter of the base end of the cathode peak”, and each ridge line L1, The angle θ (°) at which L2 intersects is the “taper taper angle of the cathode tip”, and the input current value is I (ampere).
(Formula 1) 0.332 ≦ I ² /(D1×D2×θ)≦2.904

Formula 1 above defines the ratio of the input current value to the volume of the cathode apex 32 and relates to the temperature of the cathode apex 32, and the value of “I ² / (D1 × D2 × θ)” is obtained. By adjusting optimally, the above-mentioned flicker phenomenon and the shape deformation of the cathode 3 can be suppressed.
That is, the flicker phenomenon as described above is caused by the fact that the temperature of the arc generation surface, that is, the tip surface 32c of the cathode tip 32 is not uniform, and locally high and low temperatures are formed. Therefore, it can be suppressed by uniformly setting the outer end surface 32c of the cathode tip 32 to a high temperature state without unevenness. Therefore, in order to suppress the occurrence of the flicker phenomenon, the value calculated by Equation 1 is made smaller than the predetermined value by reducing the ratio of the denominator “(D1 × D2 × θ)” to the numerator “I ² ” of Equation 1. It is preferable to increase the size.

On the other hand, the deformation of the shape of the cathode 3 is caused by the extremely high temperature of the outer end surface 32c of the cathode peak 32, and is suppressed by appropriately maintaining the temperature of the cathode peak 32. be able to. Therefore, in order to suppress the occurrence of shape deformation of the cathode 3, the value calculated by Equation 1 is set to a predetermined value by increasing the ratio of the denominator “(D1 × D2 × θ)” to the numerator “I ² ” of Equation 1. It is preferable to make it smaller than this value.

In this way, by adjusting the ratio of the amount of current input to the volume of the cathode 3 to an appropriate size so as not to be too large or too small, the spot mode and the defuse mode are adjusted. Regardless of which state the ultrahigh pressure mercury lamp 100 is turned on, the problems of flicker phenomenon and cathode shape deformation can be reliably solved. Specifically, as is clear from the experimental results described later, the value of “I ² / (D1 × D2 × θ)” in Formula 1 is preferably 0.332 to 2.904.

  In particular, the present invention is preferably employed in the ultra-high pressure mercury lamp 100 that is lit with a so-called energy-saving method that is lit with an input power that is lower than the rated power. Specifically, when the rated power is W, This is effective for lighting with input power in the range of 140W to 350W. That is, when the ultra-high pressure mercury lamp is turned on in an energy-saving manner, the outer end surface 32c of the cathode peak 32, which is the arc generating surface, is likely to cause temperature unevenness locally. Since the temperature unevenness of the pointed head 32 can be reduced to such an extent that no problem occurs in practice, the occurrence of the flicker phenomenon can be reliably prevented.

Below, the experiment conducted in order to confirm the effect of this invention is demonstrated.
According to the configuration of the ultrahigh pressure mercury lamp 100 shown in FIGS. 1 and 2, the outer diameter D1 of the tip 32a of the cathode tip 32, the outer diameter D2 of the base 32b of the cathode tip 32, the taper angle θ, and the input Five ultra-high pressure mercury lamps having different current value I factors according to Table 1 were produced based on the following specifications.
The arc tube 1 has a maximum outer diameter of the light emitting portion 11 of 12 mm, an overall length of the light emitting portion 11 of 11 mm, an outer diameter of the sealing portions 12a and 12b of 7.0 mm, and an overall length of the sealing portions 12a and 12b of 25 mm, respectively. is there.
The anode 2 has a total length of 13.5 mm including the anode shaft portion 21 and the anode body portion 22, an outer diameter of the anode shaft portion 21 of 1.0 mm, a total length of the anode shaft portion 21 of 6 mm, and the maximum outside of the anode body portion 22. The diameter is 3.0 mm, and the total length of the anode main body is 7.5 mm.
The cathode 3 has a total length of 11 mm including the cathode shaft portion 31 and the cathode tip 32, an outer diameter of the cathode shaft portion 31 (excluding the coil portion) of 1.3 mm, a total length of the cathode shaft portion 10 of 10 mm, The total length of the pointed head 32 is 1 mm, the maximum outer diameter of the coil portion 33 is 1.8 mm, and the total length of the coil portion 33 is 0.75 mm.
The amount of mercury enclosed is 0.26 mg / mm ³ , and the amount of halogen gas enclosed is 1 × 10 ⁻⁶ μmol / mm ³ .
Each of such ultra high pressure mercury lamps 100 was continuously lit for 2 hours under a lighting condition of an input power of 285 W and an input current of 3.6 A, and then the power was reduced to confirm the occurrence of a flicker phenomenon. The case where none of the 5 flickers occurred was evaluated as “◯”, and the case where even one of the 5 flickers occurred was evaluated as “x”.
Further, for each of these ultra-high pressure mercury lamps, an operation of turning on continuously for 30 minutes under a lighting condition of an applied power of 320 W and an applied current of 4.0 A, turning on for 3 minutes and then turning off for 3 minutes is defined as one cycle. After performing 5 cycles, the presence or absence of shape deformation of the cathode tip of the cathode was confirmed. The case where no shape deformation occurred in one of the five pieces was evaluated as “◯”, and the case where even one of the five shapes deformed was evaluated as “x”. The results are shown in Table 1. In Table 1, “S” indicates that the lighting state is the spot mode, and “D” indicates that the lighting state is the defuse mode.

As is clear from the results shown in Table 1, according to the ultrahigh pressure mercury lamp of the present invention that satisfies the relationship of the above formula 1, the flicker phenomenon occurs when the lamp is turned on and the shape of the cathode peak is deformed. It was confirmed that both can be suppressed.
On the other hand, according to the ultra-high pressure mercury lamp that does not satisfy the relationship of the above formula 1, it has been found that either a flicker phenomenon occurs when the lamp is turned on or the shape of the cathode peak is deformed. did.

It is sectional drawing of the pipe-axis direction which shows the outline of a structure of the ultrahigh pressure mercury lamp of this invention. It is an enlarged view which shows the structure of the cathode of the ultrahigh pressure mercury lamp shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Super high pressure mercury lamp 1 Light emission tube 11 Light emission part 12a, 12b Sealing part 2 Anode 21 Anode shaft part 22 Anode body part 22a Root part 22b Intermediate part 22c Tip part 3 Cathode 31 Cathode axis part 32 Cathode peak part 32a Cathode tip Head end 32b Cathode apex base end 32c Cathode apex outer end surface 33 Coil portions 4a, 4b Metal foils 5a, 5b External leads

Claims (2)

A light emitting part in which an anode and a cathode are arranged opposite to each other and 0.15 mg / mm ³ or more of mercury is sealed is formed to extend along the tube axis continuously at both ends of the light emitting part. A light emitting tube comprising a pair of sealing portions, a pair of metal foils embedded in each of the pair of sealing portions and extending along the tube axis, and a tip side connected to each of the pair of metal foils And a pair of external leads extending along the tube axis so that the base end side protrudes outward from the outer end surface of the sealing portion,
The cathode extends along the tube axis, and the base end side is embedded in the sealing portion and is connected to the tip end side of the metal foil, and is continuously formed on the tip end side of the cathode shaft portion. In the ultra-high pressure mercury lamp provided with the cathode cusp gradually narrowing toward the tip side,
The cathode is charged with the outer diameter of the distal end of the cathode apex being D1, the outer diameter of the base end of the cathode apex being D2, and the taper angle of the cathode apex being θ. An ultra-high pressure mercury lamp satisfying the relationship represented by the following formula 1 when the current value is I.
(Formula 1) 0.332 ≦ I ² /(D1×D2×θ)≦2.904   2. The ultrahigh pressure mercury lamp according to claim 1, wherein the cathode shaft portion and the cathode peak portion are made of tungsten having a purity of 99.9% or more.

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