JPH0467297B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a discharge lamp sealing device, and in particular, a conductive rod for support in a discharge lamp (for example, a xenon lamp) having a glass envelope in which xenon or the like is sealed. It is possible to prevent disconnection of the conductive foil that electrically connects the metal cylinder holding the discharge lamp electrode through the glass container and the current collecting disk placed behind the glass container. The present invention relates to a discharge lamp sealing device. (Prior Art) FIG. 3 is a partial sectional view showing an example of a conventional discharge lamp sealing device. In the figure, a glass enclosure 1 is made of quartz glass or the like, houses a discharge lamp electrode 2 therein, and has a narrow cylindrical neck portion 1A.
A columnar glass body 6 made of quartz glass or the like is disposed inside the neck portion 1A. A metal cylinder 4 made of molybdenum or the like is arranged on the front side of the glass body 6. A columnar current collecting disk 8 is arranged behind the glass body 6. A plurality of conductive foils 5 made of molybdenum or the like are disposed on the circumferential surface of the glass body 6 and extend in the length direction along the circumferential surface. The conductive foil 5
As shown in the figure, both ends of the metal cylinder 4 and the current collecting disk 8 are fixed to the circumferential surfaces thereof and are electrically conductively connected to each other. Further, as clearly shown in the figure, the supporting conductive rod 3 and the external lead rod 7 are penetrated through holes provided at the centers of the metal cylinder and the current collecting disk 8, respectively, and are inserted by means such as welding. fixed to each. The discharge lamp sealing device shown in FIG. 3 is assembled, for example, by the following steps. (1) Supporting conductive rod 3 with electrode 2 fixed to the front end
The rear end of the metal cylinder 4 is inserted into the center hole and fixed by welding or the like. (2) A plurality of strip-shaped conductive foils 5 are fixed to predetermined positions on the outside of the metal cylinder 4 by welding or the like so as to extend toward the rear of the metal cylinder 4. (3) A glass enclosure 6 made of the same type of quartz glass as the enclosure 1 is brought into contact with the back surface of the metal cylinder 4,
The conductive foils 5 are arranged so as to extend along the circumferential surface of the glass body 6. (4) The current collecting disk 8 with the external lead rod 7 inserted and fixed into its center hole is brought into contact with the back surface of the glass housing 6, and the conductive foil 5 is attached to the periphery of the current collecting disk 8 by welding or the like. It twists and sticks. (5) Electrode 2 constructed by the above steps (1) to (4)
- Supporting conductive rod 3 - Metal cylinder 4 - Conductive foil 5 - Glass housing 6 - Current collecting disk 8 - External lead rod 7 assembly is attached to the neck part 1A of the glass enclosure 1.
and position it. (6) Heat and pressurize the assembly and the neck portion 1A from the outside to weld and integrate the neck portion 1A, the conductive foil 5, and the glass body 6 to complete the heat and pressure seal. In the discharge lamp sealing device manufactured as described above, the glass portion (neck portion 1A) due to the difference in thermal expansion
In order to prevent damage to the metal cylinder 4, the outer circumferential surface of the metal cylinder 4 and the inner surface of the neck portion 1A are in contact or pressure contact (not welded or fixed). Incidentally, there has been a conventional demand for downsizing of lamp houses in discharge lamps. For this reason, in the past, the thickness (length in the axial direction) of the metal cylinder 4 was reduced to achieve the size reduction. Note that, in the case of a discharge lamp such as a xenon lamp, the diameter of the metal cylinder 4 is approximately determined by the current value. (Problems to be Solved by the Invention) The above-described conventional techniques had the following problems. As mentioned above, in order to downsize the lamp house, the conventional discharge lamp sealing device is designed to minimize the thickness of the metal cylinder 4 that holds the electrode 2 via the supporting conductive rod 3. It had been done. However, as described above, since the outer circumferential surface of the metal cylinder 4 and the inner surface of the neck portion 1A are in contact or pressure contact, the metal cylinder 4
will be tilted, but if the thickness of the metal cylinder 4 is small, the maximum tilt will be large. For this reason, as shown in FIG. 4, accidents often occur in which the conductive foil 5 is disconnected due to the tensile force associated with the inclination or due to elastic fatigue associated with repeated inclinations. In particular, such a condition was remarkable in a discharge lamp sealing device in which the weight of the electrode 2 was large and the length of the supporting conductive rod 3 was long. Note that FIG. 4 is a partially enlarged view schematically showing an exaggerated state in which the metal cylinder 4 in FIG. 3 is tilted to the maximum. In FIG. 4, the conductive foil 5 located at the bottom of FIG. 3 is omitted. As described above, the reason why the metal cylinder 4 is tilted is that during the heating and pressure sealing, that is, for example, when the softening point of quartz glass is 1660°C, the diameter of the glass body 6 and the diameter of the molybdenum metal cylinder 4 are approximately equal. Although they have the same diameter, when cooled to room temperature, the diameter of the metal cylinder 4 becomes smaller due to the difference in expansion coefficient between the two (molybdenum has a larger expansion coefficient). That is, the diameter of the metal cylinder 4 becomes smaller than the inner diameter of the neck portion 1A, causing wobbling. The present invention has been made to solve the above-mentioned problems. (Means and effects for solving the problem) In order to solve the above problem, the present invention provides a method for calculating the minimum thickness of the metal cylinder 4 necessary to prevent the conductive foil from being disconnected. The feature is that the thickness of the metal cylinder is greater than or equal to the calculated value. The inventor believes that the cause of disconnection in the conductive foil is that, as mentioned above, by reducing the thickness of the metal cylinder, the maximum inclination angle of the metal cylinder increases, and as a result, the conductive foil stretches and exceeds its limit. Based on this, we determined the thickness of the metal cylinder so that it could be held at the maximum inclination of the metal cylinder to the extent that the conductive foil could be stretched without exceeding the elongation limit. The minimum value was specified. Note that the units of the dimensions indicated by the symbols a, b, y, Δa, and Δb are mm, respectively. (Example) The present invention will be described in detail below with reference to the drawings. FIG. 1 is a partial sectional view of an embodiment of the present invention. FIG. 2 is a partially enlarged view schematically showing a state in which the metal cylinder 4 in FIG. 1 is tilted to its maximum extent. In FIG. 2, the conductive foil 5 located at the bottom of FIG.
is omitted. Note that these figures are also reference figures for deriving the formula for calculating the thickness of the metal cylinder 4. In these figures, the same reference numerals as in FIGS. 3 and 4 represent the same or equivalent parts. Symbols a, b, y in Figures 1 and 2,
Δa and Δb each indicate the following dimensions. a...Diameter of the metal cylinder 4 at room temperature after heat and pressure sealing b...Thickness of the metal cylinder 4 y...Conductivity from the front surface of the glass body 6 to a conductive connection point at a predetermined position on the circumferential surface of the metal cylinder 4 Length of the foil 5 (Note that in this length range, the conductive foil 5 is not welded or fixed to the inner surface of the neck portion 1A, so it can expand and contract. Therefore, in the following, , this y is called the free length.) Δa...Due to the difference between the inner diameter of the neck portion 1A and the diameter a, the maximum inclination angle θ of the metal cylinder 4 (Fig. 2)
When this occurs, the length of the perpendicular line from the lower end of the back surface of the metal cylinder 4 to the inner surface of the neck portion 1A (hereinafter referred to as gap width). Diameter a or gap width Δa
The dimensions of can be ignored. Δb...Length by which the conductive foil 5 is stretched by the maximum inclination angle θ of the metal cylinder 4 (hereinafter simply referred to as extension) As mentioned above, the heat and pressure sealing process is performed, and then the discharge lamp sealing device is heated to room temperature. If the average expansion coefficient of the metal cylinder 4 is larger than that of the glass body 6, the diameter a of the metal cylinder 4 becomes smaller than the inner diameter of the neck portion 1A. For this reason, when external vibrations or the like are applied, the metal cylinder 4 reaches its maximum inclination angle θ, and a gap width Δa occurs. That is, the metal cylinder 4 comes to wobble inside the neck portion 1A. In FIG. 2, triangle X and triangle Y have a similar relationship. Therefore, the following equations (1) and (2) hold true. Δb/a=Δa/b...(1) ∴Δb=Δa×a/b...(2) On the other hand, if the allowable elongation rate of the conductive foil 5 is α, then the free length y portion of the conductive foil 5 The extension limit of is αy. Therefore, if the extension Δb has a value that satisfies the following equation (3), disconnection of the conductive foil 5 will not occur. Δb≦αy (3) Furthermore, equation (4) is derived from equations (2) and (3) above. Δa×a/b≦αy ∴b≧Δa×a/αy (4) By the way, the gap width Δa is approximately as follows:
The inner diameter of the neck portion 1A at room temperature and the metal cylinder 4
The difference between the diameter of Δa≒a×Δε×ΔT (5) By substituting the equation (5) into the above equation (4), the equation (6) is obtained. b≧Δε×ΔT×a ² /αy (6) In equation (6), the symbol Δε indicates the difference in average coefficient of expansion between the glass body 6 and the metal cylinder 4, and its unit is 1/°C. . Further, the symbol ΔT indicates the difference between the softening point of the glass body 6 and room temperature, and its unit is °C. Therefore, if the thickness of the metal cylinder 4 is defined so that equation (6) is satisfied, the conductive foil 5 will not be disconnected. From equation (6) above, it can be seen that if the diameter a of the metal cylinder 4 is the same, the larger the free length y is, the smaller the thickness b of the metal cylinder 4 can be. Here, as described above, the material of the glass enclosure 1 and the glass enclosure 6 is quartz glass, and the metal cylinder 4 is made of quartz glass.
Then, when the conductive foil 5 is made of molybdenum, the thickness b at which the conductive foil 5 does not break is determined. The temperature difference ΔT between the softening point of quartz glass, 1660°C, and room temperature is expressed in equation (7) below, and the average expansion coefficient of molybdenum, 65×10 ^-7 , and the average expansion coefficient of quartz glass, 5×
The difference Δε from 10 ⁻⁷ is shown in the following equation (8). ΔT＝1660−20＝1640℃ ……(7) Δε＝65×10 ^-7 −5×10 ^-7 =0.6×10 ^-5 ……(8) Adding formulas (7) and (8) to the above formula (6) ), formula (9) holds true. b≧0.6×10 ^-5 ×1640×a ² /αy ≒0.01×a ² /αy ...(9) Therefore, the elongation limit of the molybdenum conductive foil 5 is not exceeded - that is, the molybdenum metal cylinder 4 is In order to prevent the conductive foil 5 from breaking even due to the rattling, the thickness b of the metal cylinder 4 should be defined so that equation (9) holds true. By the way, the elongation factor α of the molybdenum conductive foil 5 subjected to heat and pressure sealing treatment (annealing treatment) was approximately 0.1, according to the experimental results of the present inventor. Therefore, using α=0.1 and formula (9), an example of the thickness b of the molybdenum metal cylinder 4 according to the diameter a and the free length y is determined as shown in Table 1.

[Table] As is clear from Table 1, if the diameter a of the metal cylinder 4 is the same, the larger the free length y is, the
It can be seen that the thickness b of the metal cylinder 4 may be small. Note that the elongation rate α is determined by the processing state of the conductive foil 5 and the like. In addition, if necessary, the safety coefficient k (however, k
is greater than 1) to transform equation (6) into equation (10). b≧Δε×ΔT×k×a ² /αy (10) (Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved. (1) From equation (6) or equation (10) above, the required minimum value of the thickness of the metal cylinder to prevent disconnection of the conductive foil can be determined. Therefore, it is possible to prevent the disadvantage that the thickness of the metal cylinder is made even smaller than the required minimum value in an attempt to downsize the lamp house as in the past, which results in disconnection of the conductive foil. Further, it is also possible to eliminate the drawback that the thickness of the metal cylinder 4 is made too thick than necessary in order to prevent the risk of wire breakage, resulting in an oversized lamp house.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of an embodiment of the present invention. FIG. 2 is a partially enlarged view schematically showing the state in which the metal cylinder in FIG. 1 is tilted to the maximum extent. FIG. 3 is a partial sectional view showing an example of a conventional discharge lamp sealing device. FIG. 4 is a partially enlarged view schematically showing the state in which the metal cylinder in FIG. 3 is tilted to its maximum extent. 1...Glass enclosure, 1A...Network part, 2...
Discharge lamp electrode, 3... Conductive rod for support, 4... Metal cylinder, 5... Conductive foil, 6... Glass container () body,
8...Disk for current collection.

Claims (1)

[Scope of Claims] 1. A glass enclosure having a cylindrical neck portion, and a metal member disposed within the neck portion and having a conductive rod for supporting an electrode fixed to the central axis thereof so as to extend forward. a cylinder, a glass body disposed behind the metal cylinder, a current collecting disk disposed behind the glass body, and a current collecting disk disposed along the periphery of the glass body, both ends of which are arranged along the periphery of the glass body; In a discharge lamp sealing device that has a metal cylinder and a plurality of conductive foils conductively connected to a current collecting disk, and in which the glass body, the conductive foil, and the neck are welded, ΔT (°C) is expressed as The temperature difference between the softening point of the material forming the body and room temperature, Δε (/°C), is the difference between the average coefficient of expansion of the material forming the metal cylinder and the average coefficient of expansion of the material forming the glass body, a (mm) is the diameter of the metal cylinder, y (mm) is the free length of the conductive foil from the front surface of the glass body to the conductive connection point at a predetermined position on the periphery of the metal cylinder, and α is the length of the conductive foil. A discharge lamp sealing device characterized in that the thickness b (mm) of the metal cylinder is selected so as to satisfy the following formula: b≧Δε×ΔT×a ² /αy when the elongation rate is an allowable one. 2 Add safety factor k to the above formula (k is greater than 1)
, and the thickness b of the metal cylinder is selected such that b≧Δε×ΔT×k×a ² /αy. Electric light sealing device. 3. The discharge lamp sealing device according to claim 1 or 2, wherein the conductive foil is made of molybdenum. 4. The discharge lamp sealing device according to claim 1, 2, or 2, wherein the metal cylinder is made of molybdenum. 5. The discharge lamp sealing device according to claim 1, 2, 3 or 2, wherein the neck portion and the glass body are made of quartz glass.