JP2011049136A - Method of manufacturing metal foil for high-pressure discharge lamp, high-pressure discharge lamp and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a metal foil for a high-pressure discharge lamp, appropriate for manufacture of a lamp capable of restricting a breakage of a discharge container due to a crack. <P>SOLUTION: This method of manufacturing a metal foil for a high-pressure discharge lamp sealed inside of a seal part of a discharge container in the state that an electrode is connected to one end in the longitudinal direction and an external lead wire is connected to the other end includes: an electrolytic polishing process for performing electrolytic-polishing to at least a part of an outer peripheral edge of a foil piece as a precursor of the metal foil into a knife edge shape; and a chemical polishing process for performing chemical polishing to a surface of the part formed into a knife edge shape by the electrolytic polishing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a metal foil for a high-pressure discharge lamp, a high-pressure discharge lamp using the metal foil, and an image display device, and more particularly to a technique for processing an edge of the metal foil into a knife edge shape.

  As an example of a high-pressure discharge lamp, for example, it has a glass discharge container composed of a light emitting part and a sealing part connected to the light emitting part, and mercury is enclosed as a light emitting substance in the discharge space in the light emitting part. There is a high-pressure mercury lamp. Since the mercury vapor pressure during lighting is as high as 10 to 100 [atm] (1 to 10 [MPa]), the lamp needs high airtightness. Therefore, an electrode assembly formed by joining the electrode, the metal foil, and the external lead wire in this order is assembled, and the electrode assembly is sealed in the sealing portion. The assembly is hermetically sealed to ensure the hermeticity of the lamp.

  In recent years, so-called ultra-high pressure discharge lamps have been manufactured in which the mercury vapor pressure during lamp operation reaches about 200 [atm]. In such an ultra-high pressure discharge lamp, the edge of the metal foil is processed into a knife edge shape to reduce stress concentration on the glass near the metal foil when sealing the electrode assembly, and in the vicinity of the metal foil. This prevents cracks from occurring in the glass.

JP 2004-227970 A

  Currently, for the purpose of increasing the lamp efficiency, the development of next-generation ultra-high pressure mercury lamps with mercury vapor pressure exceeding 300 [atmospheric pressure] is underway. A difficult lamp structure is required. However, as described above, simply processing the edge of the metal foil into a knife-edge shape cannot withstand an ultra-high pressure exceeding 300 [atm], causing cracks in the glass near the metal foil, fall into disrepair.

  An object of this invention is to provide the manufacturing method of the metal foil for high pressure discharge lamps suitable for manufacture of the lamp | ramp with which the failure | damage of the discharge vessel resulting from a crack does not occur easily in view of said subject. Another object of the present invention is to provide a highly reliable high pressure discharge lamp in which the discharge vessel is hardly damaged. Another object of the present invention is to provide an image display device that is easy to maintain because it includes a high-pressure discharge lamp with high reliability.

  In order to achieve the above object, the method for producing a metal foil for a high-pressure discharge lamp according to the present invention is sealed in a sealing portion of a discharge vessel with an electrode bonded to one end in the longitudinal direction and an external lead wire bonded to the other end. A method for producing a metal foil for a high-pressure discharge lamp that is stopped by an electropolishing step in which at least a part of an outer peripheral edge of a foil piece that is a precursor of the metal foil is electropolished into a knife edge shape, and by electropolishing And a chemical polishing step of chemically polishing the surface of the portion having the knife edge shape.

A high-pressure discharge lamp according to the present invention is a pair of a discharge vessel comprising a light emitting part having a discharge space and a sealing part connected to the light emitting part, an electrode, a metal foil, and an external lead wire joined in this order. A high-pressure discharge lamp in which the pair of electrode structures are sealed in the sealing portion in a state where the entire metal foil is embedded in the sealing portion. The foil is characterized in that at least a part of the outer peripheral edge has a knife edge shape, and the surface of the knife edge shaped part is subjected to chemical polishing for removing deposits made of crystal grains. To do.

  An image display device according to the present invention includes the high-pressure discharge lamp.

  The method for producing a metal foil for a high-pressure discharge lamp according to the present invention includes an electropolishing step of electropolishing at least a part of an outer peripheral edge of a foil piece that is a precursor of the metal foil into a knife edge shape, and a knife edge by electropolishing. And a chemical polishing step of chemically polishing the surface of the shaped part, so that the deposits attached to the surface of the knife edge shaped part after the electropolishing can be removed. Therefore, the metal foil manufactured by the method is smooth with few deposits on the surface of the knife edge-shaped portion, and has good adhesion to glass. Therefore, the high-pressure discharge lamp manufactured using the metal foil is highly reliable because mercury vapor or the like hardly enters between the glass of the sealing portion and the metal foil, and as a result, cracks hardly occur.

In the high-pressure discharge lamp according to the present invention, at least a part of the outer peripheral edge of the metal foil has a knife edge shape, and chemical polishing for removing deposits made of crystal grains is performed on the surface of the knife edge shaped portion. Therefore, cracks hardly occur in the vicinity of the edge of the metal foil, and the discharge vessel is hardly damaged.
Since the image display apparatus according to the present invention includes the high-pressure discharge lamp, the number of lamp replacements is less than that of the conventional image display apparatus, and maintenance is easy.

The top view which shows the lamp unit using the high pressure discharge lamp which concerns on 1st Embodiment. It is a figure which shows the metal foil which concerns on this Embodiment, Comprising: (a) is a top view, (b) is a front view, (c) is a right view, (d) is the AA line in (a). Sectional drawing along, (e) is sectional drawing along the BB line in (a) The partially broken perspective view which shows the image display apparatus which concerns on 2nd Embodiment The perspective view which shows the image display apparatus which concerns on 3rd Embodiment. It is a figure which shows the knife edge shape part of the foil piece after an electrolytic polishing process and before a chemical polishing process, (a) is sectional drawing, (b) is the surface state seen from the arrow direction in (a). Electron micrograph, (c) is a schematic diagram showing the surface state in the range indicated by symbol G in (b). Electron micrograph showing the surface state of the knife edge shape part of the foil piece The figure which shows the experimental result about electropolishing The figure which shows the experimental result about chemical polishing The figure which shows the experimental result about the case where electrolytic polishing and chemical polishing are applied The figure which shows the experimental result about the case where electrolytic polishing and chemical polishing are applied The figure which shows the experimental result about the case where electrolytic polishing and chemical polishing are applied It is a figure which shows the metal foil which concerns on the modification 1, Comprising: (a) is a top view, (b) is a front view, (c) is a right view, (d) is along the AA line in (a). (E) is a sectional view taken along line BB in (a). It is a figure which shows the metal foil which concerns on the modification 2, Comprising: (a) is a top view, (b) is a front view, (c) is a right view, (d) is along the AA line in (a). (E) is a sectional view taken along line BB in (a).

Hereinafter, a method for manufacturing a metal foil for a high pressure discharge lamp according to the present embodiment, a high pressure discharge lamp using the metal foil, and a display device will be described with reference to the drawings. In addition, the scale of the member in each drawing differs from an actual thing. In the present invention, the sign “˜” indicating a numerical range includes numerical values at both ends.
[High pressure discharge lamp]
FIG. 1 is a plan view showing a lamp unit using a high-pressure discharge lamp according to the first embodiment, in which a housing is cut away so that the inside can be seen. As shown in FIG. 1, the lamp unit 100 includes a housing 101 and a high-pressure discharge lamp 102 according to the first embodiment incorporated in the housing 101.

The high-pressure discharge lamp 102 is a so-called double-end type high-pressure mercury lamp, and includes a discharge vessel 110 made of, for example, quartz glass and a pair of electrode assemblies 120. The high-pressure discharge lamp is not limited to a double-end type, and may be a so-called single-end type, for example.
The discharge vessel 110 includes a light emitting unit 111 and a pair of sealing units 112 provided on both sides of the light emitting unit 111. For example, the light emitting unit 111 has a substantially spherical shape with an outer diameter of about 12 [mm] and an inner diameter of about 5 [mm], and has a discharge space 113 with an inner volume of about 0.1 [cm ³ ] inside. Note that the outer diameter and inner diameter of the light emitting unit 111 and the inner volume of the discharge space 113 are not limited to the above, and can be appropriately changed according to the specifications of the high-pressure discharge lamp 102.

In the discharge space 113, for example, mercury as a luminescent material is about 0.3 [mg / mm ³ ], a rare gas as a starting aid is about 30 [kPa], and bromine (Br) as a halogen material is about 10 ⁻⁷ [μmol / mm ³ ] to 10 ⁻² [μmol / mm ³ ] are enclosed, and the mercury vapor pressure during lamp operation is about 300 [atm]. Note that the light-emitting substance is not limited to mercury, and may be an alkali metal atom or the like. Examples of the rare gas include argon (Ar), krypton (Kr), xenon (Xe), or a mixed gas of at least two of them, and argon is preferable. Examples of the halogen substance include iodine (I), bromine (Br), chlorine (Cl), or a mixture of at least two of them, and bromine is preferable. Further, the mercury vapor pressure during lamp operation is not limited to about 300 [atm], and may be lower or higher than that.

  The pair of sealing portions 112 are, for example, substantially cylindrical shapes having an outer diameter of about 5.2 [mm] and a length of about 25 [mm], and the electrode assembly 120 is sealed in each. One sealing portion 112 is fixed to the housing 101 with, for example, cement, and the other sealing portion 112 is located in the housing 101. The outer diameter, length, and shape of the sealing portion 112 are not limited to the above, and can be changed as appropriate according to the specifications of the high-pressure discharge lamp 102.

Each electrode assembly 120 includes an electrode 130, a metal foil 140, and an external lead wire 150. The electrode 130, the metal foil 140, and the external lead wire 150 are joined in this order, for example, by welding. The metal foil 140 is sealed with the sealing portion 112.
Each electrode 130 has a rod-shaped electrode shaft 131 made of, for example, tungsten, and a tungsten coil 132 wound around one end of the electrode shaft 131 and constituting the tip of the electrode 130. The tip portions of the discharge vessel 110 are opposed to each other in the discharge space 113, and the end portion opposite to the tip portion is embedded in the sealing portion 112. ing. For example, in the case of a high-pressure discharge lamp used in a projection-type image display device (in the case of a so-called short arc type high-pressure discharge lamp), the distance between the tip portions of the pair of electrodes 130 is set close to a point light source. , 0.5 [mm] to 2.0 [mm] is preferable.

2A and 2B are diagrams showing a metal foil according to the present embodiment, where FIG. 2A is a plan view, FIG. 2B is a front view, FIG. 2C is a right side view, and FIG. 2D is A in FIG. Sectional view along line -A, (e) is a sectional view along line BB in (a).
Each metal foil 140 has, for example, a substantially strip shape made of molybdenum, and has a longitudinal width L of about 20 [mm] and a lateral width W of about 1. As shown in FIG. 5 [mm], as shown in FIG. 2B, the wall thickness t is about 20 [μm]. The width L in the longitudinal direction, the width W in the lateral direction, and the thickness t of the metal foil 140 are not limited to the above, but the width L in the longitudinal direction is 10 [mm] to 30 [mm]. The width W in the direction is preferably in the range of 1.0 [mm] to 2.0 [mm], and the thickness t is in the range of 10 [μm] to 30 [μm].

  More specifically, as shown in FIG. 2A, the shape of the metal foil 140 is obtained by obliquely cutting off two corners on one side in the longitudinal direction of the rectangle (the side to which the electrode 130 is joined) in plan view. The substantially hexagonal outer periphery has a pair of opposing long sides 141 and 142, a pair of opposing short sides 143 and 144, and two oblique sides 145 generated by cutting off the two corners. 146, the long sides 141 and 142 are both about 19 [mm] long, and the short sides 143 and 144 are about 1.5 [mm] shorter and about 0.7 [shorter]. [Mm] and the lengths of the hypotenuses 145 and 146 are both about 1.0 [mm]. The lengths of the long sides 141 and 142, the short sides 143 and 144, and the oblique sides 145 and 146 are not limited to the above.

The metal foil 140 is subjected to electrolytic polishing and chemical polishing in this order. Whether or not the electrolytic polishing is performed can be confirmed by whether or not at least a part of the outer peripheral edge of the metal foil 140 is processed into a knife edge shape. The chemical polishing can be confirmed by whether or not molybdenum deposits are present in the vicinity of the outer peripheral edge of the metal foil.
As shown in FIGS. 2B to 2D, the metal foil 140 includes at least a part of the outer peripheral edge, specifically, the vicinity of the long sides 141 and 142 (both edges in the short direction of the metal foil 140). Are processed into a knife edge shape. By adopting such a knife edge shape, stress concentration on the glass near the metal foil 140 when the electrode assembly 120 is sealed is reduced, and the glass near the metal foil 140 is less likely to crack. . In addition, only either one side edge part of a transversal direction may be processed into the knife edge shape.

On the other hand, as shown in FIGS. 2B and 2E, the vicinity of the short sides 143 and 144 (longitudinal ends of the metal foil 140) are not processed into a knife edge shape, and the flat end surface 143a is not processed. , 144a.
Returning to FIG. 1, the electrode 130 is joined to one end of the metal foil 140 in the longitudinal direction, and the external lead wire 150 is joined to the other end. The entire metal foil 140 is embedded in the sealing portion 112. As described above, the metal foil 140 is interposed between the electrode 130 and the external lead wire 150, and the electrode assembly 120 is sealed mainly in the metal foil 140 portion, thereby ensuring the airtightness of the discharge space 113. ing.

The external lead wire 150 has an end on the metal foil 140 side embedded in the sealing portion 112, and an end opposite to the metal foil 140 is led out from the sealing portion 112 to the outside.
The housing 101 includes a reflecting member 160 and a lens member 170. The reflecting member 160 is, for example, a dichroic reflecting mirror having a funnel shape and a concave reflecting surface 161 on the inside, and the light emitted from the light emitting unit 111 of the high-pressure discharge lamp 102 on the reflecting surface 161 is irradiated in the direction (lens Reflected on the member 170 side).

  A lens member 170 is attached to the opening 162 having the larger diameter (irradiation direction side) of the reflecting member 160 so as to close the opening 162. The reflecting member 160 and the lens member 170 are made of, for example, a silicone-based member. Bonded with an adhesive (not shown) or the like. In addition, one sealing portion 112 of the high-pressure discharge lamp 102 is inserted from the inside of the housing 101 into the opening 163 on the small diameter side (opposite direction to the irradiation direction) of the reflecting member 160, and the sealing The portion 112 is fixed to the reflecting member 160 with, for example, cement 103 or the like.

  The external lead wire 150 led out from the sealing portion 112 fixed to the reflecting member 160 is connected to the lead wire 104 of the connector (not shown) via the connection sleeve 105 outside the housing 101. On the other hand, the external lead wire 150 led out from the sealing portion 112 located in the housing 101 is led out to the outside of the housing 101 through the through hole 164 formed in the reflective surface 161 of the reflective member 160 and is connected to the connector. Connected to a lead wire (not shown).

[Image display device]
FIG. 3 is a partially broken perspective view showing the image display apparatus according to the second embodiment, and the top plate of the housing is removed so that the inside can be seen. As shown in FIG. 3, the image display apparatus 200 according to the second embodiment is a projection-type front projector that projects an image toward a screen (not shown) installed in the front, and is a DLP (registered trademark). The method is adopted. The image display apparatus 200 includes a lamp unit 100 serving as a light source, an optical unit 202 having a DMD (registered trademark), a color wheel (not shown) including three color filters, and the like in the housing 201, the DMD. The control unit 203 for driving and controlling the projector, the projection lens 204, the cooling fan unit 205, the power supply unit 206 that converts the power supplied from the commercial power supply into power suitable for the control unit 203 and the lamp unit 100, and the like Is stored.

  FIG. 4 is a perspective view showing an image display apparatus according to the third embodiment. As shown in FIG. 4, the image display apparatus 300 according to the third embodiment is a projection-type rear projector, and includes a lamp unit 100 as a light source, an optical unit (not shown), a projection lens (not shown), and A mirror (not shown) or the like is housed in the housing 301, and an image projected from the projection lens and reflected by the mirror is projected from the back side of the transmissive screen 302 to display an image.

Since the image display apparatuses 200 and 300 according to the second and third embodiments use the high-pressure discharge lamp 102 that is highly reliable and has a long life because the discharge vessel 110 is unlikely to be damaged, the conventional image display apparatus is used. In comparison, the number of times of replacement of the high-pressure discharge lamp 102 or the replacement of the lamp unit 100 is small, and maintenance is easy.
[Method for producing metal foil]
The manufacturing method of the metal foil according to the present embodiment is characterized by a polishing process, and is different from the conventional manufacturing method in that respect. Other processes basically conform to the conventional manufacturing method. Below, only a grinding | polishing process is demonstrated in detail, and it abbreviate | omits or demonstrates about another process.

  In the metal foil manufacturing method according to the present embodiment, first, a molybdenum foil plate is cut into rectangular strips to obtain a foil piece as a precursor. Next, the edge part of a foil piece is grind | polished by a grinding | polishing process, and metal foil is obtained. The polishing process includes an electropolishing process and a chemical polishing process. First, the edge portion of the foil piece is processed into a knife edge shape in the electropolishing process, and then the portion electropolished in the chemical polishing process, that is, the knife edge shape. Remove deposits from the surface of the part.

Electropolishing is suitable for processing the edge portion of a foil piece into a knife edge shape because a specific portion can be selectively polished, but has a problem that deposits are generated on the surface of the knife edge shape portion. If an adherent is attached to the surface of the metal foil, the adhesion to the glass deteriorates at that portion, so that the glass is likely to crack. In the case of a conventional high-pressure discharge lamp with a mercury vapor pressure of about 200 [atm], cracks did not occur even if adhering material adhered, but if the mercury vapor pressure exceeds 300 [atm], If the kimono is attached, cracks are generated, and thus the attached matter needs to be removed.

  Therefore, in the manufacturing method according to the present embodiment, after electrolytic polishing, the knife edge-shaped portion is further polished by chemical polishing to remove deposits from the surface. Chemical polishing is suitable for removing deposits because the surface of the polishing portion can be uniformly polished. In addition, since the edge part of a foil piece cannot be processed into a knife edge shape by chemical polishing, a target metal foil cannot be obtained only by chemical polishing, and electrolytic polishing is indispensable.

  5A and 5B are diagrams showing a knife edge shape portion of the foil piece after the electrolytic polishing step and before the chemical polishing step, where FIG. 5A is a cross-sectional view, and FIG. 5B is a view from the arrow direction in FIG. (C) is a schematic diagram showing a surface state in a range indicated by a symbol G in (b). In addition, the area | region shown to Fig.5 (a) in the foil piece 180 is corresponded to the area | region shown with the code | symbol F of FIG.2 (d) in the metal foil 140. FIG.

  As shown in FIG. 5A, the deposit 183 made of molybdenum crystal grains adheres to the surface 182 of the knife edge-shaped portion 181 of the foil piece 180. In the electron micrograph of FIG. 5B, the surface 182 of the knife-edge shaped portion 181 is shown in gray, and the whitish part and the inner part surrounded by the whitish part are the deposits 183. The outer peripheral edge 184 of the deposit 183 shown in FIGS. 5A and 5C corresponds to the boundary between the gray portion of the surface 182 and the whitish portion of the deposit 183 in FIG. The size of the deposit 183 when the surface 182 of the knife edge-shaped portion 181 is viewed from the direction orthogonal to the surface 182 is the area of the region surrounded by the outer peripheral edge 184. This area means the area of a region that covers a projection formed by vertical projection on the surface 182.

The deposit 183 having a size of 25 [μm ² ] or more causes cracks in particular, but when the relationship between the deposit and the crack is visually confirmed, the deposit having a size of 25 [μm ² ] or more is observed. In the absence of 183, it was confirmed that no cracks occurred. Therefore, it is preferable that there is no particle having a size of 25 [μm ² ] or more by dissolving or reducing the deposit 183 by chemical polishing.

  FIG. 6 is an electron micrograph showing the surface state of the knife edge-shaped portion of the foil piece. In FIG. 6, the observation points C to E of the foil piece 180 correspond to the portions indicated by the symbols C to E in FIG. When the foil piece 180 is chemically polished, it can be seen that the size and quantity of the deposit 183 is reduced at any of the observation points C to E with the lapse of the polishing time, and the deposit 183 is removed.

Details of the electrolytic polishing step will be described below. In the electrolytic polishing step, the foil piece is polished by passing a direct current through the electrolytic polishing solution between the foil piece as the anode and the cathode. The electropolishing strength is determined by the product of the current value of the direct current and the time during which the direct current is passed. The setting of the current value and the time is basically free, but for this, experimental results as shown in FIG. 7 are obtained.
FIG. 7 is a diagram showing experimental results for electropolishing. For experiment, a metal foil that was subjected only to electropolishing without chemical polishing was manufactured, and a high-pressure discharge lamp was manufactured using the metal foil. The experimental high-pressure discharge lamp has substantially the same configuration as the high-pressure discharge lamp 102 according to the first embodiment except for the metal foil, and the mercury vapor pressure is about 300 [atm]. In the electropolishing, a 2 [wt%] NaOH (sodium hydroxide) aqueous solution was used as the electropolishing liquid, and various current values and times were set.

Then, various high-pressure discharge lamps that were manufactured were lit to check for damage (n = 10). If breakage occurs with the sealing portion as the starting point within the lighting time of 100 hours, it is evaluated as “X”, and if similar breakage occurs in excess of 100 h and within 1000 hours, it is evaluated as “Δ”, and the same applies until 2000 h. When damage did not occur, it was evaluated as “◯”. Since the same experiment was performed for a high-pressure discharge lamp having a mercury vapor pressure of about 200 [atm], the experimental result is shown in parentheses in FIG.

As shown in FIG. 7, when the mercury vapor pressure was about 300 [atm], no high-pressure discharge lamp was evaluated as “◯” regardless of how the current value and time were set. This is because chemical polishing is not performed. When the mercury vapor pressure is about 300 [atm], it is understood that electrolytic polishing alone is insufficient.
In addition, when the mercury vapor pressure was about 200 [atm], there was a high-pressure discharge lamp with an evaluation of “◯”. When the electropolishing strength is in a suitable range (the product of the current value and time is preferred) and the edge of the metal foil is suitably processed into a knife edge shape, the evaluation is considered to be “◯”. . If the electropolishing strength is too weak, that is, if the product of the current value and the time is too small, it is considered that the edge portion does not have a knife edge shape and breakage occurs. On the other hand, if the electropolishing strength is too strong, that is, if the product of the current value and the time is too large, the edge portion is excessively polished, the metal foil becomes thin, and it is considered that damage is caused by current concentration.

  As conditions other than the current value and time in electropolishing, the type, concentration, temperature, etc. of the electropolishing liquid can be considered, but these settings are free. Basically, the type, concentration, temperature, and the like of the electropolishing liquid do not greatly affect the electropolishing strength, but affect the finished state of the knife edge shape. In addition, as a kind of electropolishing liquid, KOH aqueous solution etc. can be considered besides NaOH aqueous solution.

Details of the chemical polishing step will be described below. In the chemical polishing step, the foil piece is immersed in a chemical polishing solution to polish the foil piece. The chemical polishing strength is determined by the product of the concentration of the chemical polishing solution and the time for dipping the foil piece. The setting of the concentration and time is basically free, but for this, experimental results as shown in FIG. 8 are obtained.
FIG. 8 is a diagram showing experimental results for chemical polishing. As an experiment, a metal foil that was subjected only to chemical polishing without electrolytic polishing was manufactured, and a high-pressure discharge lamp was manufactured using the metal foil. The experimental high-pressure discharge lamp has substantially the same configuration as the high-pressure discharge lamp 102 according to the first embodiment except for the metal foil, and the mercury vapor pressure is about 300 [atm]. For chemical polishing, hydrogen peroxide solution at room temperature was used, and the current value and time were variously set.

Then, each manufactured high-pressure discharge lamp was turned on and examined for damage. The evaluation criteria are the same as in the experiment for electropolishing. Since the same experiment was conducted for a high-pressure discharge lamp having a mercury vapor pressure of about 200 [atm], the experimental result is shown in parentheses in FIG.
As shown in FIG. 8, not only when the mercury vapor pressure was about 300 [atm], but also when the mercury vapor pressure was about 200 [atm], there was no high-pressure discharge lamp with an evaluation of “◯”. . This is because the electropolishing is not performed, and it can be seen from this result that chemical polishing alone is insufficient.

As conditions other than the concentration and time in chemical polishing, the type and temperature of the chemical polishing liquid can be considered, but these settings are free. As the type of chemical polishing liquid, hydrofluoric acid or the like can be considered in addition to the hydrogen peroxide solution. Moreover, since it becomes difficult to control polishing if it is boiling, the temperature of the chemical polishing liquid is preferably less than 100 ° C., more preferably normal temperature.
FIG. 9 is a diagram showing experimental results when electrolytic polishing and chemical polishing are performed. For experiment, a metal foil subjected to electrolytic polishing and further subjected to chemical polishing was manufactured, and a high pressure discharge lamp was manufactured using the metal foil. The experimental high-pressure discharge lamp has substantially the same configuration as the high-pressure discharge lamp 102 according to the first embodiment except for the metal foil, and the mercury vapor pressure is about 300 [atm]. As electrolytic polishing conditions, a 2 wt% NaOH aqueous solution was used as the electrolytic polishing liquid,
The current value was set to 200 [mA] and the time was set to 6 [s]. As chemical polishing conditions, room temperature hydrogen peroxide was used as the chemical polishing solution, and the concentration x [wt%] and time t [min] were variously set.

Then, each manufactured high-pressure discharge lamp was turned on and examined for damage. The evaluation criteria are the same as in the experiment for electropolishing. The values in parentheses in FIG. 9 are the product of concentration x [wt%] and time t [min].
As shown in FIG. 9, when the conditions of 3 ≦ x ≦ 25, 5 ≦ t ≦ 60, and 30 ≦ xt ≦ 300 are satisfied, the evaluation is “ A high-pressure discharge lamp “○” was obtained. Since the edge part of metal foil was processed into the knife edge shape, and the deposit | attachment was removed from the surface, it is thought that the breakage did not occur. In the case of t <5 or xt <30, it is considered that the damage occurred because the deposits were not sufficiently removed. In the case of t> 60 or xt> 300, it is considered that the metal foil was thinned by polishing and the current density was excessively increased, or the metal foil was thinned by polishing and the foil was broken, so that it was considered damaged. If the concentration x [wt%] is too high, the polishing time width becomes narrow and polishing control becomes difficult, and if it is too thin, the polishing time becomes too long and inefficient. It is preferably in the range of 10 [wt%] to 15 [wt%].

  10 and 11 are diagrams showing experimental results when electrolytic polishing and chemical polishing are performed. In the experiment according to FIG. 10, a 5 [wt%] NaOH aqueous solution was used as an electropolishing condition, the current value was set to 200 [mA], and the time was set to 6 [s]. As chemical polishing conditions, hydrogen peroxide water was used, the concentration was set to 3 [wt%], and the time was set to 15 [min]. In the experiment according to FIG. 11, a 5 [wt%] aqueous NaOH solution was used as an electropolishing condition, the current value was set to 300 [mA], and the time was set to 2 [s]. As chemical polishing conditions, hydrogen peroxide water was used, the concentration was set to 3 [wt%], and the time was set to 10 [min].

  As shown in FIGS. 10 and 11, when only electrolytic polishing is performed (Comparative Example 1-1, Comparative Example 2), or when electrolytic polishing is performed after chemical polishing (Comparative Example 1-2), high-voltage discharge is performed. Although the lamp was damaged, when chemical polishing was performed after electrolytic polishing (Example 1 and Example 2), the high-pressure discharge lamp was not damaged, and the manufacturing method according to the present embodiment has a mercury vapor pressure. It turns out that it is effective for the manufacture of a high-pressure discharge lamp of about 300 [atm].

[Modification]
As mentioned above, although the manufacturing method of the metal foil for high pressure discharge lamps which concerns on this invention, the high pressure discharge lamp, and the display apparatus were demonstrated concretely based on embodiment, the content of this invention is limited to said embodiment. Not.
<Metal foil>
The metal foil is not limited to the shape like the metal foil 140 according to the first embodiment, and may be the shape like the metal foil according to the following modified example 1 and modified example 2, for example.

12A and 12B are diagrams showing a metal foil according to the first modification, in which FIG. 12A is a plan view, FIG. 12B is a front view, FIG. 12C is a right side view, and FIG. Sectional drawing along A line, (e) is sectional drawing along the BB line in (a).
As shown in FIG. 12A, the metal foil 440 according to Modification 1 is, for example, a substantially strip shape made of molybdenum, and the shape in plan view is one side in the longitudinal direction of the rectangle (the electrodes are joined). A substantially hexagonal shape with two corners on the side) cut off obliquely, and the outer periphery of the substantially hexagonal shape is formed by a pair of opposing long sides 441 and 442, a pair of opposing short sides 443 and 444, and the two corners It is composed of two hypotenuses 445 and 446 generated by cutting off.

As shown in FIGS. 12B to 12D, the metal foil 440 is processed in a knife edge shape in the vicinity of the long sides 441 and 442 (both ends in the short direction of the metal foil 440). 12 (c) and 12 (e), the vicinity of the short sides 443 and 444 (longitudinal end edges of the metal foil 440) is also processed into a knife edge shape. As described above, since both end edges in the longitudinal direction have a knife edge shape, stress concentration on the glass in the vicinity of both end edges in the longitudinal direction can be reduced, and a high-pressure discharge lamp that is less prone to crack can be obtained. In addition, as shown in FIGS. 12B and 12C, in the metal foil 440, the vicinity of the hypotenuses 445 and 446 is also processed into a knife edge shape. Therefore, it is hard to produce a crack further.

It should be noted that only one of the longitudinal end edges may be processed into a knife edge shape. In this case, it is effective to process the electrode side where cracks are likely to occur because the temperature is high during lamp operation into a knife edge shape. Further, only a part of the vicinity of the oblique sides 445 and 446 may be processed into a knife edge shape.
FIGS. 13A and 13B are diagrams showing a metal foil according to Modification Example 2, wherein FIG. 13A is a plan view, FIG. 13B is a front view, FIG. 13C is a right side view, and FIG. Sectional drawing along A line, (e) is sectional drawing along the BB line in (a). As shown in FIG. 13A, the metal foil 540 according to the modified example 2 is, for example, a substantially strip shape made of molybdenum, and the shape in plan view is opposed to a pair of long sides 541 and 542 facing each other. It is a rectangle composed of a pair of short sides 543 and 544.

As shown in FIGS. 13B to 13D, the portions near the long sides 541 and 542 of the metal foil 540 (both ends in the short direction) are processed into a knife edge shape. In addition, the structure which processed the vicinity part (longitudinal direction both ends edge part) of the short sides 543 and 544 to the knife edge shape may be sufficient, and it can be set as the structure which a crack does not produce more easily in that case.
As another modification example of the metal foil, it is conceivable to improve the pressure resistance performance by adding an anchor effect to the metal foil by providing irregularities on the outer periphery of the metal foil. Further, when chemical etching is performed, in addition to the effect of removing molybdenum deposits generated on the outer peripheral edge of the metal foil after the above-described electropolishing, the metal foil can be slightly oxidized. can get. When the metal foil is oxidized in this way, the metal foil becomes more compatible with quartz glass, and as a result, the occurrence of breakage near the interface between the quartz glass and the metal foil can be further suppressed.

<Manufacturing method>
The electrolytic polishing conditions in the electrolytic polishing step, that is, the current value and time for applying a direct current, and the type, concentration and temperature of the electrolytic polishing liquid are not limited to the conditions described in the above embodiment.
Further, the electrolytic polishing may be performed by passing an alternating current. In this case, the same conditions as those of the direct current described in the above embodiment can be used for the current value and time to flow and the type and concentration of the electrolytic polishing liquid.
In the case of electropolishing with a direct current, a concentration gradient of the electrolytic solution is likely to occur. Therefore, it is preferable to stir the electrolytic solution at regular intervals. On the other hand, in the case of electropolishing with an alternating current, bubbles are likely to be generated at both electrodes, and the electrolyte solution is stirred without separately stirring the electrolyte solution, which can make it difficult to generate a concentration gradient of the electrolyte solution. .
In addition, the conditions for chemical polishing in the chemical polishing step, that is, the type, concentration and temperature of the electrolytic polishing liquid, the time for immersion in the electrolytic polishing liquid, and the like are not limited to the conditions described in the above embodiment. When chemical polishing is performed, a small amount of current may flow between the foil piece as an anode and a cathode through a chemical polishing liquid. Here, the trace amount means a value at which the outer peripheral edge of the foil piece cannot be processed into a knife edge shape, but the surface deposits can be removed.

  In the above embodiment, the case of applying to a high-pressure discharge lamp having a mercury vapor pressure of about 300 [atm] during lighting has been described in detail, but a high-pressure mercury lamp having a mercury vapor pressure of 300 [atm] or less, or low-pressure mercury. It can also be applied to lamps. Further, the present invention can be applied to other discharge lamps other than the mercury lamp, and for example, can be applied to a discharge lamp such as a metal halide lamp enclosing a metal halide.

DESCRIPTION OF SYMBOLS 102 High pressure discharge lamp 111 Light emission part 112 Sealing part 110 Discharge container 120 Electrode assembly 130 Electrode 140 Metal foil 140 'Foil piece 183 Adherence 150 External lead wire 200,300 Image display apparatus

Claims (5)

A method for producing a metal foil for a high-pressure discharge lamp that is sealed in a sealing portion of a discharge vessel with an electrode bonded to one end in the longitudinal direction and an external lead wire bonded to the other end,
Electrolytic polishing step of electrolytic polishing at least a part of the outer peripheral edge of the foil piece, which is a precursor of the metal foil, into a knife edge shape, and chemical polishing step of chemically polishing the surface of the knife edge shape portion by electrolytic polishing The manufacturing method of the metal foil for high pressure discharge lamps characterized by including these. In the chemical polishing step, in the hydrogen peroxide water, at least the knife edge-shaped portion of the foil piece is immersed and chemically polished,
When the concentration [wt%] of the hydrogen peroxide solution is x and the immersion time [min] is t, the conditions of 3 ≦ x ≦ 15, 5 <t <90, and 30 <xt <400 are satisfied. The method for producing a metal foil for a high-pressure discharge lamp according to claim 1.   3. The method for producing a metal foil for a high-pressure discharge lamp according to claim 1, wherein in the electrolytic polishing step, the outer peripheral edge of the foil piece is electrolytically polished into a knife edge shape over the entire circumference. A discharge vessel comprising a light emitting part having a discharge space and a sealing part connected to the light emitting part, and a pair of electrode assemblies in which electrodes, metal foil and external lead wires are joined in this order, A high pressure discharge lamp in which the pair of electrode structures are sealed in the sealing portion in a state where the entire metal foil is embedded in the sealing portion,
The metal foil is such that at least a part of the outer peripheral edge has a knife edge shape, and the surface of the knife edge shaped portion is subjected to chemical polishing for removing deposits made of crystal grains. High-pressure discharge lamp characterized.   An image display device comprising the high-pressure discharge lamp according to claim 4.

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