JP2005142075A - Flash discharge tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a flash discharge tube in order to meet the demands of the market in recent years, depending on a set tube diameter and arc length, an extreme light quantity and a shortage of life may occur, or an impact during discharge Caused problems such as damage.
According to the present invention, by limiting the inner diameter of the glass envelope to 0.65 to 1.0 mm, a flash discharge lamp having an outer diameter of 2 mm or less is used to secure a light quantity, and the cross-sectional area S2 of the main electrode 3 is baked. The lifetime is ensured by setting the cross-sectional area S1 of the bonded body 4 to 3.950 to 5.685 times, and further, the outer diameter of the glass envelope is set to 0.031 ≦ {(πD ² based on the inner diameter and the arc length. -Πd ² ) / L} is set so that it can be prevented from being damaged by the impact of discharge at the time of lighting, so that a practical ultra-compact flash discharge tube can be realized and the problem can be solved. .
[Selection] Figure 1

Description

  The present invention relates to a flash discharge tube that is used for illumination when taking a picture at night, and more specifically, to a compact device such as a digital camera, a digital movie, or a mobile phone with a camera. For example, the present invention relates to a flash discharge tube that is required to be miniaturized.

FIG. 7 shows an example of the structure of a conventional flash discharge tube 90 of this type, and a thin flash discharge tube with a glass tube bulb 91 having an inner diameter of 1.2 mm or less. When the diameter of the bulb 91 is reduced in this way, it becomes difficult to form a cathode installed in the bulb 91. Therefore, the cathode support member 92 made of a metal member such as tungsten or molybdenum has An emitter 93 formed of a sintered material having substantially the same diameter is fixed by a connecting member 94 having a sheath shape.
Japanese Patent Laid-Open No. 06-243824

  However, when actually reducing the size of the flash discharge tube, there is no problem only in the configuration of the cathode described above. For example, if the inside diameter and outside diameter are simply reduced at the conventional ratio, Since it becomes impossible to mechanically withstand impacts, there are new issues such as the need to set the outer diameter specification based on some parameters, and it is impossible to achieve miniaturization unless more comprehensive measures are taken. Become. Further, as shown by a curve E in FIG. 8, in this type of flash discharge tube, generally, when the arc length is shorter than 10 mm, the light emission efficiency is abruptly lowered, and there is a problem that the light quantity is likely to be insufficient. Therefore, at present, the minimum value of the flash discharge tube is considered to be a dimension having an inner diameter of 1 mm, an outer diameter of 1.8 mm, and an arc length of about 10 mm.

In the present invention, as a specific means for solving the above-described conventional problems, first, the glass seal is required to be ultra-miniaturized with an outer diameter of 2 mm or less and an arc length of 10 mm or less. Is a flash discharge tube to which a sintered body having a substantially donut-shaped cross section is attached, and 0.65 mm ≦ inner diameter d <1 mm of glass sealed body (preferably 0.75 mm ≦ inner diameter D of glass sealed body ≦ 0. 95 mm), and secondly, the outer diameter D of the glass envelope, the inner diameter d of the glass envelope, and the arc length L which is the distance between the main electrodes A flash discharge tube characterized in that the relationship is 0.031 ≦ {(πR ² −πr ² ) / L}, and thirdly, the cross-sectional area of the sintered body with respect to the cross-sectional area of the main electrode Ratio of 3.950 ≦ (S1 / S2) ≦ 5.685 (preferably 4.340 ≦ S1 / S2) ≦ 5.685) that to provide a flash discharge tube, wherein a, is intended to solve the problem.

  Below, this invention is demonstrated in detail based on embodiment shown in a figure. 1 is a flash discharge tube according to the present invention. The flash discharge tube 1 includes a glass envelope 2 formed in a substantially tubular shape with glass, and discharge chambers from both ends of the glass envelope 2. A main electrode 3 protruding into 2a, a sintered body 4 attached to one of the main electrodes 3, and a discharge gas 5 such as xenon gas sealed in the discharge chamber 2a. This is the same as that of the conventional example. In the present invention, minimization is achieved while maintaining the configuration of the conventional example as much as possible.

  And in this invention, when the ultra-small size which makes the outer diameter of the glass sealing body 2 2 mm or less is requested | required, the internal diameter d of the glass sealing body 2 is limited to the range of 0.65 mm-1.00 mm. Furthermore, it is even more preferable to limit to the range of 0.75 mm to 0.95 mm. That is, in the present invention, for example, a glass sealed body 2 having an inner diameter of 1.8 mm, a wall thickness of 0.1 mm, and an outer diameter of 2 mm, etc. There is a range not adopted.

  FIG. 2 is a graph showing the results of trial manufacture and examination conducted by the inventor in order to achieve the present invention. This graph measures the luminous efficiency by changing the inner diameter of the glass envelope 2 for each arc length. The arc length in the range from 1 mm to 7 mm shown in the figure shows the highest luminous efficiency when the inner diameter is 0.85 mm, both when the inner diameter is made thicker and thinner. It was confirmed that the luminous efficiency tends to decrease.

  In the figure, the symbol d100 is a curve showing the luminous efficiency for each arc length in the glass envelope 2 having an inner diameter of 1 mm. Similarly, the symbol d095 has an inner diameter of 0.95 mm, and d085 has an inner diameter of 0. .85 mm, d075 is an inner diameter of 0.75 mm, d065 is an inner diameter of 0.65 mm, and d050 is a curve showing luminous efficiency for each arc length when the inner diameter is 0.50 mm. In the drawing, the arc length is shown in the range of 1 to 7 mm, but this tendency is the same even when the arc length is in the range of 7 mm or more, for example, the arc length is 20 mm.

  Therefore, for example, when the glass envelope 2 having an inner diameter of 0.85 mm is adopted, as is apparent from the above graph, except when the external dimensions of the glass envelope 2 are restricted due to other factors such as design. However, the brightest lighting can be achieved. In practice, when this type of flash discharge tube 1 is used, it is usual to use a reflecting mirror that employs a curved surface having a focal point, such as a rotating paraboloid system.

  When a reflecting mirror having a curved surface having a focal point is employed, light that is emitted in an unscheduled direction and becomes invalid as the light source image is smaller, in other words, closer to a point light source, is out of focus. The amount of light is reduced, and an illumination shape as designed and a bright light distribution characteristic can be obtained.

  Therefore, if the luminous efficiency of the flash discharge tube 1 using the glass envelope 2 having an inner diameter of 1 mm and the luminous efficiency of the flash discharge tube 1 using the glass envelope 2 having an inner diameter of 0.85 mm are the same The illumination efficiency after combining the reflecting mirror and the lens is more advantageous when the diameter is small. In the present invention, in consideration of these requirements, the flash discharge tube 1 is miniaturized. The inner diameter of the glass envelope 2 is limited to a range of 0.65 mm to 1.00 mm (preferably, 0.75 mm to 0.95 mm).

The above is an explanation of the inner diameter of the glass envelope 2 that directly affects the brightness and the like. However, in the present invention, the outer diameter of the glass envelope is simultaneously defined. And the arc length L, which is the distance between the main electrodes, is 0.031 ≦ {(πD ² −πd ² ) / L}.

  The above expression is an expression for obtaining the outer diameter D as a value related to the arc length L when the inner diameter d is constant, and the obtained outer diameter D is the arc length for each value of the inner diameter d set above. The minimum value in L is obtained. Here, the reason why the required thickness of the glass envelope 2 is changed by the arc length L is that the lighting power applied to the flash discharge tube 1 is changed by the arc length L. Does require a lot of power. In FIG. 3, the outer diameter corresponding to the arc length L when the inner diameter is 0.95 mm is shown as a curve D.

  Therefore, the mechanical impact applied to the glass envelope 2 during discharge becomes stronger as the arc length L becomes longer, and the possibility of breakage becomes higher. Therefore, when further miniaturization of the flash discharge tube 1 is attempted, In this way, it is necessary to set a limit value according to the use conditions from the viewpoint of preventing accidents due to careless miniaturization.

  When the glass sealed body 2 is downsized as described above, the lamp current at the time of discharge increases with the shortening of the arc length L, and the consumption of the main electrode 3 and the sintered body 4 becomes severe. In addition, the diameter of the sintered body 4 is reduced as the diameter of the glass sealed body 2 is reduced, and the amount of cesium and cesium compound impregnated in the sintered body 4 is reduced, leading to an increase in starting voltage. . All of these lead to a shortened life of the flash discharge tube.

  In the inventor of the present invention, as a result of studying the above problems from various aspects, when the ratio of the cross-sectional areas of the main electrode 3 and the sintered body 4 is kept within a certain range, It has been found that it is possible to give practically sufficient brightness and life to the flash discharge tube 1 which has been downsized.

  As shown in FIG. 4, the range is such that the ratio of the cross-sectional area S1 of the sintered body 4 to the cross-sectional area S2 of the main electrode is in the range of 3.950 ≦ (S1 / S2) ≦ 5.685. . However, in the present invention, both the main electrode 3 and the sintered body 4 have a cylindrical shape with a constant diameter, and a hole 4a corresponding to the outer diameter of the main electrode 3 is provided at the center of the sintered body 4, and this hole 4a. The main electrode 3 is passed through and fixed by welding or the like.

  Curve V shown in FIG. 5 is an observation of the transition of the lighting voltage when the ratio of (S1 / S2) between the main electrode 3 and the sintered body 4 configured as described above is changed. Sometimes, other conditions such as the inner diameter of the glass sealing body 2, the type of the discharge gas 5, the sealing pressure, the distance between the main electrodes 3, that is, the arc length L are exactly the same, and the sintered body 4 is impregnated. The amount of cesium and cesium compound to be produced is also the same.

  From the results of the above tests, it can be clearly understood that the lighting voltage decreases almost linearly as the area ratio on the sintered body 4 side is increased. It is predicted that the lighting voltage decreases as the area S1 is larger than the cross-sectional area S2 of the main electrode 3, which will be advantageous for downsizing of the lighting circuit, for example.

  A curve F shown in FIG. 6 is the same procedure as in the above test, changing the cross-sectional area ratio between the main electrode 3 and the sintered body 4, repeating lighting 3000 times for each area ratio, and setting the initial value to 100 % Is a measurement of the luminous flux maintenance factor at the 3000th time. Also in this test, the other conditions such as the inner diameter of the glass envelope 2, the type of discharge gas 5, the sealing pressure, the distance between the main electrodes 3, that is, the arc length L are exactly the same, and the sintering The amount of cesium and cesium compound impregnated in the body 4 is also the same.

  From the above test results, when the cross-sectional area S1 of the sintered body 4 is approximately 4 to 5.5 times the cross-sectional area S2 of the main electrode 3, 90% or more of the light flux with respect to the initial light amount. It was confirmed that it could be maintained. In addition, the decrease in the luminous flux maintenance factor in the range where the ratio of the sintered body 4 is 5.5 times or more reduces the cross-sectional area S2 of the main electrode 3 relative to the cross-sectional area S1 of the sintered body 4, that is, Since it becomes relatively thin, it is considered that the main electrode 3 side is consumed in this range.

  From the above test results, in the present invention, the ratio N of the cross-sectional area S1 of the sintered body 4 to the cross-sectional area S2 of the main electrode 3 is 3.950 ≦ N ≦ 5.685 (preferably 4.340). ≦ N ≦ 5.685), and in this way, it is possible to maintain a light intensity maintenance rate of 90% or more even after 3000 lightings, and to guarantee practicality It is.

  As described above, when the flash discharge tube 1 is miniaturized, first, by setting the inner diameter of the glass envelope 2 to 0.65 mm to 1 mm, the luminous efficiency is high at the inner diameter in the vicinity thereof. In addition, it is possible to easily select a range where the light distribution characteristics can be formed efficiently because it is close to a point light source even with a reflecting mirror, and the light quantity that can withstand practical use is obtained even when ultra-miniaturized. This simplifies the process.

  At this time, assuming that the arc length L is used as a reference, an outer diameter (tube thickness) that can withstand the impact caused by the lighting voltage when each arc length L is obtained is obtained. It shall be possible to prevent the body 2 from being damaged and to prevent accidents. In addition, since the appropriate outer diameter can be easily obtained, the design can be simplified.

  In addition, according to the present invention, the range of the cross-sectional area ratio between the main electrode 3 and the sintered body 4 can be set to an appropriate value, so that the luminous flux maintenance factor is about 90% or more even when the lighting is repeated a plurality of times. As what is kept, it is possible to repeatedly illuminate a sufficient number of times, for example, in photography, and to guarantee practicality.

  Since the flash discharge tube 1 can be miniaturized while guaranteeing the practicality of the flash discharge tube 1, it has been adopted in digital cameras and digital video cameras that have been further miniaturized in recent years. It is possible to reduce the size of the strobe device to a size that can be installed, and to meet market demands.

  In recent years, many mobile phones are equipped with ultra-miniaturized digital cameras for the purpose of further improving the convenience of being carried around at all times. Even for a strobe device that has been requested, the present invention can be mounted with a necessary and sufficient ultra-miniaturization and can meet market demands.

It is sectional drawing which shows embodiment of the flash discharge tube which concerns on this invention. It is a graph which shows the change of the emitted light amount when changing the internal diameter in the flash discharge tube of this invention for every arc length. It is a graph which shows the relationship between the arc length and the outer diameter of the flash discharge tube which concerns on this invention. It is a perspective view which shows the combined state of the main electrode which is the principal part of the flash discharge tube which concerns on this invention, and a sintered compact. It is a graph which shows the change of a lighting voltage when changing the ratio of the cross-sectional area of a main electrode and a sintered compact. It is a graph which shows the light beam change rate after repeated lighting when changing the ratio of the cross-sectional area of a main electrode and a sintered compact. It is sectional drawing which shows a prior art example. It is a graph which shows the relationship between the arc length and the emitted light amount in this kind of flash discharge tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flash discharge tube 2 ... Glass sealed body 3 ... Main electrode 4 ... Sintered body 5 ... Gas for discharge

Claims (3)

  In a flash discharge tube in which an outer diameter of 2 mm or less and an arc length of 10 mm or less are required for a glass sealed body, and a sintered body having a substantially donut-shaped cross section is attached to a main electrode, 0.65 mm ≦ A flash discharge tube characterized by having an inner diameter d <1 mm of the glass envelope (preferably, 0.75 mm ≦ inner diameter D ≦ 0.95 mm of the glass envelope). The relationship between the outer diameter D of the glass envelope, the inner diameter d of the glass envelope, and the arc length L, which is the distance between the main electrodes, is 0.031 ≦ {(πD ² −πd ² ) / L}. The flash discharge tube according to claim 1, characterized in that:   The ratio (S1 / S2) of the sectional area S1 of the sintered body to the sectional area S2 of the main electrode is 3.950 ≦ (S1 / S2) ≦ 5.685 (preferably 4.340 ≦ (S1 / S2). 3. The flash discharge tube according to claim 1, wherein: ≦≦ 5.685).

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