JP4940723B2 - Short arc type ultra high pressure discharge lamp - Google Patents

Description

The present invention relates to a short arc type ultra-high pressure discharge lamp. In particular, a liquid crystal display device or DMD (digital mirror device) using an ultrahigh pressure discharge lamp with 0.15 mg / mm ³ or more of mercury enclosed in an arc tube and a mercury vapor pressure of 110 atm or more when lit is used as a light source. The present invention relates to a discharge lamp for a light source used in a projector apparatus such as a DLP (digital light processor).

The projection type projector device is required to illuminate an image with a uniform and sufficient color rendering property on a rectangular screen. Therefore, as a light source, 0.15 mg / mm ³ or more of mercury is enclosed. Lamps with high mercury vapor pressure are used.

In this type of lamp, for example, a pair of electrodes are arranged opposite to each other at an interval of 2 mm or less on an arc tube made of quartz glass, and 0.15 mg / mm ³ or more of mercury and 1 × 10 ⁻⁶ to 1 × are disposed on the arc tube. An ultra-high pressure discharge lamp in which halogen is enclosed in the range of 10 ⁻² μmol / mm ³ is used. The main purpose of enclosing the halogen is to prevent devitrification of the arc tube, but this also causes a so-called halogen cycle. As the electrode, a so-called molten electrode obtained by melting a coil is used.

  FIG. 4 shows a schematic configuration of a short arc type ultrahigh pressure discharge lamp having a molten electrode. The electrode is in a form in which a coil is wound around a tungsten rod and only the tip portion of the coil is melted, whereby the tip portion becomes a lump shape, and the coil exists at the rear end. The coil functions as a starting seed (starting start position) due to the surface irregularity effect when the lamp is turned on, and has a heat dissipation function due to the surface irregularity effect and the heat capacity after lighting. This type of discharge lamp is described in, for example, Japanese Patent Application Laid-Open No. 2004-247092.

In the above discharge lamp, it is preferable to make the coil thinner in order to improve startability. On the other hand, in order to enhance the heat dissipation effect, the coil needs to be in close contact with the electrode shaft. That is, since the contact area with the electrode shaft decreases as the coil becomes thinner, these two requirements contradict each other.
Japanese Patent Application Laid-Open No. 2004-247092

  The problem to be solved by the present invention is to provide a short arc type ultra-high pressure discharge lamp capable of enhancing startability during lighting and sufficiently exhibiting a heat radiation function during normal lighting.

In order to solve the above-mentioned problems, a short arc type ultra-high pressure discharge lamp according to the present invention has a pair of electrodes facing each other at intervals of 2 mm or less on an arc tube made of quartz glass, and 0.15 mg / mm on the arc tube. ^Three or more mercury, rare gas, and halogen are enclosed in the range of 1 × 10 ⁻⁶ to 1 × 10 ⁻² μmol / mm ³ . And at least one electrode of the pair of electrodes is characterized in that the tip lump portion, the plurality of flange portions arranged at intervals behind the tip portion, and the electrode shaft portion are formed by cutting one member. To do.
Further, the collar portion is characterized in that the depth is formed (extends) to the electrode shaft portion. Further, the electrode is characterized by having a protrusion at the tip of the massive portion. The ridge has a width of 0.05 mm to 0.2 mm. The ridge is characterized in that a distance between adjacent ridges is 0.1 mm to 0.5 mm.

  By having the said structure, since several narrow ridges are formed instead of a coil, lighting start can be started from the said ridges. Further, since the scissors are made by cutting from one rod-shaped member, heat conduction is smoothly performed between the scissors and the electrode shaft, and the heat dissipation effect by the scissors is sufficiently exhibited.

FIG. 1 shows an overall configuration of a short arc type ultra-high pressure discharge lamp (hereinafter also simply referred to as “discharge lamp”) according to the present invention.
The discharge lamp 1 has a substantially spherical light emitting portion 11 formed by a discharge vessel made of quartz glass, and a pair of electrodes 10 (10a, 10b) are arranged opposite to each other on the light emitting portion 11. Moreover, the sealing part 12 is formed so that it may extend from the both ends of the light emission part 11, and the conductive metal foil 13 which usually consists of molybdenum is embed | buried airtight by these shrink seals in these sealing parts 12, for example. . The pair of electrodes 10 have shaft portions welded to and electrically connected to the metal foil 13, and external leads 14 (14 a and 14 b) projecting to the outside are welded to the other end of the metal foil 13. . A trigger wire 15 is wound around the base of one external lead 14a and the electrode 10b.

The light emitting unit 11 is filled with mercury, rare gas, and halogen gas. Mercury is used to obtain a necessary visible light wavelength, for example, radiated light having a wavelength of 360 to 780 nm, and 0.15 mg / mm ³ or more is enclosed. Although the amount of sealing varies depending on the temperature condition, the vapor pressure becomes extremely high at 150 atm or higher when the lamp is turned on. In addition, by enclosing more mercury, it is possible to create a discharge lamp with a high mercury vapor pressure of 200 atm or higher and 300 atm or higher when the lamp is turned on. The higher the mercury vapor pressure, the more suitable the light source suitable for the projector device. Can be realized.
For example, the rare gas is filled with about 13 kPa of argon gas to improve the lighting startability. As the halogen, iodine, bromine, chlorine and the like are enclosed in the form of a compound with mercury or other metal, and the amount of halogen enclosed is selected from the range of 10 ⁻⁶ to 10 ⁻² μmol / mm ³ . Its function also has a longer life using halogen cycles. However, it is very small and has a high internal pressure such as the discharge lamp of the present invention. The main purpose.

For example, the discharge lamp has a maximum outer diameter of 9.5 mm, a distance between electrodes of 1.5 mm, an arc tube inner volume of 75 mm ³ , a rated voltage of 80 V, and a rated power of 150 W, and is turned on by alternating current. In addition, this type of discharge lamp is built in a miniaturized projector device, and the overall size of the device is extremely small, while a high light quantity is required. Is extremely severe, and the lamp wall load value of the lamp is 0.8 to 2.0 W / mm ² , specifically 1.5 W / mm ² . When such a high mercury vapor pressure or tube wall load value is mounted on a presentation device such as a projector device or an overhead projector, it is possible to provide emitted light with good color rendering properties.

FIG. 2 shows an enlarged view of the electrode 10.
The electrode 10 includes a front end lump portion 21, a flange portion 22, and an electrode shaft portion 23, which are manufactured by cutting one tungsten material, which will be described later. For this reason, the tip lump portion 21, the flange portion 22, and the electrode shaft portion 23 are physically configured as a single body. For the cutting process, rod-shaped tungsten is prepared and processed with a cutting tool.
The tip lump portion 21 is formed at the tip of the electrode, and the side surface facing the other electrode is formed in a substantially hemispherical shape having a spherical shape. Since the mass portion 21 is heated to a high temperature, it is necessary to ensure heat resistance, and has a certain volume. This is necessary for both electrodes in the case of AC lighting and in the electrode on the anode side in the case of DC lighting.
A plurality of flanges 22 are formed at the rear of the tip lump 21, and each of the flanges has a depth so as to extend to the electrode shaft 23. This kite corresponds to a conventional coil and functions as a starting seed (starting start position) at the time of starting, and after lighting, receives heat from the tip lump portion 21 by conduction from the electrode shaft portion 23 to dissipate heat. It has the function to do. Since it is a cocoon, it has the advantage of being easily heated. In the embodiment, the collar portion 22 is composed of three collars 22a, 22b, and 22c.
The electrode shaft portion 23 is joined to the metal foil, and not only holds the massive portion 21 and the flange portion 22 but also plays a role of electric power feeding.

In this electrode, first, discharge starts when electrons are emitted from the last end 22a. Thereafter, the electric discharge jumps forward to the flanges 22b and 22c, and finally moves to the tip lump portion 2. The reason why electrons are emitted from the last ridge 22a is that the trigger wire 15 is closest to the last ridge so that the electric field strength at the ridge increases.
A protrusion 21 a is formed on the tip surface of the block 2. Even if the protrusion 21a does not exist at the beginning, it can be generated along with the subsequent lighting, or it can be made by cutting as a growth seed in advance. The reason why electrons are emitted from the last end 22a is that the electric field is the strongest.

The protrusion 21a grows with the result of the lighting time. Although the phenomenon of this growth is not necessarily clear, tungsten constituting the electrode evaporates and combines with the halogen present in the light emitting portion, but in the arc, tungsten atoms are ionized and become cations and adhere to the tip of the electrode. It is considered a thing.
In this respect, making the growth seed in advance by cutting has an advantage that the position of the protrusion can be regulated. Conversely, if the projection is not made in advance, it may be generated at an undesired level on the spherical electrode tip surface.

FIG. 3 shows a specific shape of the electrode of the discharge lamp according to the present invention. All of the embodiments shown in (a) to (d) are formed by cutting from one tungsten material.
(A) is the same as the form shown in FIG. 2, the tip lump is spherical, and the collar is formed to the depth of the electrode axis. As numerical examples, the width of the ridge is 0.1 mm, the distance between the ridges is 0.3 mm, and the outer diameter of the electrode shaft is φ0.3 mm. This structure is suitably employed in a power saving type, for example, 50 to 150 W.
(B) is different from (a) in that the depth of the collar portion is not formed up to the electrode shaft and the axial direction of the tip lump is long. Since the depth of the collar portion is not formed up to the electrode shaft, there is an advantage that the collar portion is not easily broken. The outer diameter of the electrode shaft in the buttocks is φ0.9 mm. This structure is suitably used for a lamp with relatively high power, for example, 200 W or more.
(C) is different from (a) in that the shape of the tip is conical. This advantage is that a protrusion is formed at the apex of the tip without forming the protrusion. This structure can be used for both AC lighting and DC lighting.
(D) is that in comparison with (c), the length of the collar portion increases in order from the front end to the rear end. An advantage of this is that the arc generated at the rear end easily moves to the front end, and the design takes into consideration the orientation characteristics.

  In the present invention, the width of one ridge is preferably 0.05 to 0.2 mm. If it is less than 0.05 mm, there is a problem of causing spattering during electric discharge machining, and if it is 0.2 mm or more, it is difficult to move forward.

Furthermore, in the present invention, it is desirable that the distance between adjacent ridges is 0.1 to 0.5 mm. If it is less than 0.1 mm, it is difficult to process, and if it is 0.5 mm or more, it is difficult to move forward.
Further, in the present invention, the front lump portion and the collar portion are formed thereafter, but no special shape (for example, the rear end lump portion or the like) is provided after the collar portion.

As described above, in the short arc type ultra-high pressure discharge lamp according to the present invention, a pair of electrodes are arranged to face each other at intervals of 2 mm or less on an arc tube made of quartz glass, and 0.15 mg / mm ³ or more is disposed on the arc tube. Mercury, rare gas, and halogen are enclosed in the range of 1 × 10 ⁻⁶ to 1 × 10 ⁻² μmol / mm ³ . And at least one of the pair of electrodes is characterized in that a tip lump portion and a plurality of flange portions arranged behind the tip lump portion are formed by cutting one member.

  With this configuration, a plurality of narrow ridges are formed instead of the coil, so that the lighting can be started with the ridges as starting points. Further, since the scissors are made by cutting from one rod-shaped member, heat conduction is smoothly performed between the scissors and the electrode shaft, and the heat dissipation effect by the scissors is sufficiently exhibited.

1 shows a short arc discharge lamp according to the present invention. The structure of the electrode of the short arc type discharge lamp concerning the present invention is shown. The structure of the electrode of the short arc type discharge lamp concerning the present invention is shown. A conventional short arc type discharge lamp is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode 10 Discharge lamp 11 Light emission part 12 Sealing part 21 Tip lump part 22 Gutter part 23 Electrode axial part

Claims (5)

A pair of electrodes are arranged opposite to each other at an interval of 2 mm or less on an arc tube made of quartz glass, and 0.15 mg / mm ³ or more of mercury, a rare gas, and 1 × 10 ⁻⁶ to 1 × 10 ^{−2 are} disposed in the arc tube. In a short arc type ultra-high pressure discharge lamp in which halogen is enclosed in the range of μmol / mm ³ ,
The short arc is characterized in that at least one electrode of the pair of electrodes is formed by cutting from a single member, a tip lump portion, a plurality of flange portions arranged at intervals behind the tip lump portion, and an electrode shaft portion. Type ultra-high pressure discharge lamp.   2. The short arc type ultra high pressure discharge lamp according to claim 1, wherein the flange portion is formed to reach the electrode shaft portion.   2. The short arc type ultra high pressure discharge lamp according to claim 1, wherein the electrode has a protrusion at the tip of the lump.   The short arc type ultra-high pressure discharge lamp according to claim 1, wherein the ridge has a width of 0.05 mm to 0.2 mm. 2. The short arc type ultra-high pressure discharge lamp according to claim 1, wherein an interval between the flanges is 0.1 mm to 0.5 mm.

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