JP5397514B1 - Ceramic metal halide lamp - Google Patents

Abstract

A ceramic metal halide lamp capable of achieving a correlated color temperature of about 2500 K without sacrificing lamp life.
The additive includes thallium iodide TlI, sodium iodide NaI, calcium iodide CaI ₂ , lithium iodide LiI, and rare earth metal iodide, and further has a correlated color temperature of 2250 to 2750 K, a tube wall load. Is 20 to 30 W / cm ² , and the rated output is 35 to 400 W. The molar ratio of sodium iodide to the total number of moles of the additive is M (NaI) [mol%], rare earth metal iodide ReI _When the sum of the molar ratio of _{3 and} the molar ratio of thallium iodide TlI is M (ReI ₃ + TlI) [mol%], 4 <M (NaI) / M (ReI ₃ + TlI) <16 and 2 mol % <M (ReI ₃ + TlI) <9 mol%.
[Selection] Figure 4A

Description

  The present invention relates to a high-intensity discharge lamp, and more particularly to a ceramic metal halide lamp.

  High-intensity discharge lamps (hereinafter referred to as HID lamps) are widely used because of their high efficiency and economy. HID lamps are roughly classified into three types, mercury lamps, metal halide lamps, and high-pressure sodium lamps, depending on the type of additive sealed in the arc tube. In general, high-pressure sodium lamps have a long lifetime and high luminous efficiency, but high-saturation and color-rendering high-pressure sodium lamps are known as light sources for vividly displaying red colors, although their lifetime and luminous efficiency are inferior to ordinary high-pressure sodium lamps. It has been. In recent years, ceramic metal halide lamps using an arc tube made of ceramic (translucent alumina: PCA) instead of an arc tube made of quartz glass have been widely used. The lamp life and luminous efficiency of ceramic metal halide lamps are said to be superior to that of high chroma and color rendering high pressure sodium lamps.

  However, high-saturation and color-rendering high-pressure sodium lamps are usually used for lighting fresh food. There are various factors such as the correlated color temperature CCT, the color rendering index CRI, and the wavelength spectrum distribution. First, the correlated color temperature can be mentioned. The reason is that there is a demand for vivid colors of red lines in lighting of fresh foods such as vegetables, bread and meat.

  In the case of a high saturation high color rendering high-pressure sodium lamp, the correlated color temperature is about 2500 K. However, in the case of a ceramic metal halide lamp, the correlated color temperature is relatively high, and it is difficult to achieve about 2500 K.

  Japanese Unexamined Patent Publication No. 2004-288617 (Japanese Patent No. 4279122) discloses a ceramic metal halide lamp having a correlated color temperature of 2000 to 4500 K, Japanese Unexamined Patent Publication No. 2003-187744 and Japanese Unexamined Patent Publication No. 2009-520323. Ceramic metal halide lamps having a color temperature of 2800 to 3700K are described in ceramic metal halide lamps having a temperature of 2500 to 4500K, Japanese Patent Application Laid-Open No. 2007-53004, and Japanese Patent Application Laid-Open No. 2011-154847, respectively. However, these patent documents do not disclose specific techniques for reducing the correlated color temperature to about 2500K. In fact, the color temperature of ceramic metal halide lamps currently on the market is 2800K or higher even for low color temperature types.

JP 2004-288617 A (Patent No. 4279122) Japanese Patent Laid-Open No. 2003-1877444 (Japanese Patent No. 4262968) JP 2009-520329 A JP 2007-53004 A JP 2011-154847 JP 2010-3488

  In general, in order to lower the correlated color temperature, the content of sodium Na in the additive sealed in the arc tube may be increased. However, when the content of sodium Na is increased, the total amount of additive is increased. Thereby, the amount of erosion to translucent alumina (PCA) constituting the arc tube is increased, and the lamp life is shortened. For example, Japanese Unexamined Patent Application Publication No. 2010-3488 describes that the lamp life of a ceramic metal halide lamp is 15000 hours or more, but does not describe that a correlated color temperature of about 2500 K is achieved at the same time.

  An object of the present invention is to provide a ceramic metal halide lamp capable of achieving a correlated color temperature of about 2500 K without sacrificing lamp life.

According to the present invention, in a ceramic metal halide lamp having an arc tube formed of a translucent ceramic that encloses a pair of electrodes, and a translucent outer tube that houses the arc tube,
The arc tube encloses a starting rare gas, mercury, and an additive. The additive includes thallium iodide TlI, sodium iodide NaI, calcium iodide CaI ₂ , lithium iodide LiI, and rare earth metal iodide. includes a compound ReI _3, further correlated color temperature 2250~2750K, 20~30W / cm ² is the wall load, configured to rated output is 35～400W, and,
The molar ratio of sodium iodide to the total number of moles of the additive is M (NaI) [mol%], and the sum of the molar ratio of the rare earth metal iodide ReI _{3 and} the molar ratio of thallium iodide TlI is M (ReI ₃ + TlI ) [mol%], M (NaI) and M (ReI ₃ + TlI) satisfy the following formula.

4 <M (NaI) / M (ReI ₃ + TlI) <16
2 mol% <M (ReI ₃ + TlI) <9 mol%
According to this embodiment, G (total) [mg / cm ³ ] is the total amount of the additive per 1 cm ³ arc tube volume, and the amount of rare earth metal iodide contained in the additive per 1 cm ³ arc tube Is G (ReI ₃ ) [mg / cm ³ ], the G (total) and G (ReI ₃ ) may satisfy the following equation.

G (total) <44 mg / cm ³
G (ReI ₃ ) <11 mg / cm ³
According to this embodiment, in the ceramic metal halide lamp, the molar ratio M (NaI) of sodium iodide, the molar ratio M of calcium iodide (CaI ₂ ), and the molar ratio M of lithium iodide M ( When the sum of LiI) is M (NaI + CaI ₂ + LiI), the sum may satisfy the following formula:

50mol% <M (NaI + CaI 2 + LiI) <96mol%
According to this embodiment, in the ceramic metal halide lamp, the molar ratio M (NaI) of sodium iodide, the molar ratio M of calcium iodide (CaI ₂ ), and the molar ratio M of lithium iodide M ( LiI) may each satisfy the following equation:

30 mol% <M (NaI) <70 mol%
10 mol% <M (CaI ₂ ) <40 mol%
10 mol% <M (LiI) <30 mol%
According to this embodiment, in the ceramic metal halide lamp,
The additive may include at least one of thulium iodide TmI ₃ , dysprosium Dy, holmium Ho, and cerium Ce iodide as a rare earth metal iodide (thulium iodide TmI ₃ is essential). .

According to this embodiment, in the ceramic metal halide lamp,
The correlated color temperature of the arc tube is 2400-2600K, and the M (NaI) and M (ReI ₃ + TlI) may satisfy the following formula.

7 <M (NaI) / M (ReI ₃ + TlI) <13

  According to the present invention, a ceramic metal halide lamp capable of achieving a correlated color temperature of about 2500 K without sacrificing lamp life can be provided.

FIG. 1 is a diagram illustrating an example of an arc tube of a ceramic metal halide lamp according to the present invention. FIG. 2 is a diagram illustrating an example of a ceramic metal halide lamp according to the present invention. FIG. 3 is a diagram illustrating an example of a ceramic metal halide lamp according to the present invention. FIG. 4A is a diagram for explaining the test results of the arc tube of the ceramic metal halide lamp according to the present invention. FIG. 4B is a diagram for explaining the test results of the arc tube of the ceramic metal halide lamp according to the present invention.

  Hereinafter, embodiments of a ceramic metal halide lamp according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  An example of an arc tube of a ceramic metal halide lamp according to the present invention will be described with reference to FIG. The arc tube 2 includes a light emitting unit 3 and capillaries 4A and 4B extending at both ends thereof. The light emitting section 3 and the capillaries 4A and 4B are formed by compressing and integrally forming a light transmitting ceramic powder such as alumina. Electrode assemblies 6A and 6B are inserted through both ends of the capillaries 4A and 4B, respectively. Both ends of the capillaries 4A and 4B are hermetically sealed by frit glass having electrical insulation. Thereby, the electrode assemblies 6A and 6B are fixed in place in the capillaries 4A and 4B. The electrodes 5A and 5B provided at the inner ends of the electrode assemblies 6A and 6B are arranged at fixed positions in the light emitting unit 3. Power supply leads 7A and 7B protrude from both ends of the capillaries 4A and 4B.

  In addition to argon and mercury, an additive is enclosed in the light emitting unit 3. Additives include luminescent materials such as alkali metal iodides, alkaline earth metal iodides, rare earth metal iodides, and the like. The additive sealed in the light emitting unit 3 will be described in detail later.

  An effective length L and an effective inner diameter D are defined as inner dimensions of the arc tube 2. The effective length L is the distance between both end faces in the case of a cylindrical arc tube, and in the arc tube in which the light emitting part and the capillary are continuously formed as shown in FIG. 1, light is emitted from the straight tubular capillaries 4A and 4B. It is defined by the distance between the outer ends of the transition curved surfaces L1, L1 between the tubes 3. The effective inner diameter D is defined as the maximum inner diameter of the central portion between the electrodes 5A and 5B in a light emitting tube other than a cylindrical shape. The effective length of the arc tube 2 is L, the effective inner diameter is D, and the ratio L / D between them is called the aspect ratio.

The temperature of each part of the light emitting unit 3 is determined by the wall load of the arc tube, the gas pressure in the translucent outer tube, the arc tube material, and the aspect ratio (L / D) of the arc tube, and particularly depends greatly on the wall load. The wall surface load is defined by a value obtained by dividing the lamp power by the total inner area of the light emitting unit 3. In this embodiment, the light emission part 3 is designed so that wall surface load may be 20-30 W / cm < ² > (rated output 35-400 W). Thus, in this embodiment, the chemical reaction rate between the material constituting the inner wall surface of the light emitting part and the rare earth metal iodide can be kept low, and the life of the lamp can be extended.

  An example of a ceramic metal halide lamp according to the present invention will be described with reference to FIG. The ceramic metal halide lamp 1 of the present example includes a light emitting tube 2, a cylindrical translucent sleeve 18 disposed so as to surround the light emitting portion 3, and an outer sphere 13 provided with a base 12 at one end. The structure of the arc tube 2 has been described with reference to FIG.

  Two struts 15 and 16 are attached to the stem 14 of the base 12. Two support disks 17A and 17B are mounted on the support at predetermined intervals. A cylindrical translucent sleeve 18 is fixed to the disks 17A and 17B. A getter 20 is mounted on the disk 17B. Power supply leads 7A and 7B protrude from both ends of the capillaries 4A and 4B. The tips of the power supply leads 7A and 7B are welded to the columns 15 and 16 directly or via nickel wires 19A and 19B, respectively. Thus, the electrodes 5A and 5B of the arc tube 2 are electrically connected to the base 12 via the power supply leads 7A and 7B and the columns 15 and 16.

  An example of a ceramic metal halide lamp according to the present invention will be described with reference to FIG. The ceramic metal halide lamp 1 of this example has an arc tube 2 and an outer bulb 13. The structure of the arc tube 2 has been described with reference to FIG. An outer sphere tip-off portion 13A is formed at one end of the outer sphere 13, and a pinch seal portion 13B is formed at the other end. A base 12 is attached to the end of the pinch seal portion 13B. External terminals 9 </ b> A and 9 </ b> B are attached to the base 12.

  Two struts 15 and 16 are fixed to the pinch seal portion 13B. Power supply leads 7A and 7B protrude from both ends of the capillaries 4A and 4B. The tips of the power supply leads 7A and 7B are welded to the columns 15 and 16, respectively. A getter 20 is mounted on the column 15. The support columns 15 and 16 are electrically connected to the external terminals 9A and 9B via the metal foils 8A and 8B at the pinch seal portion 13B.

  Thus, the electrodes 5A and 5B of the arc tube 2 are electrically connected to the external terminals 9A and 9B via the power supply leads 7A and 7B, the support columns 15 and 16, and the metal foils 8A and 8B.

  The ceramic metal halide lamp according to the present invention may be a reflective ceramic metal halide lamp having a concave reflecting mirror in addition to the examples shown in FIGS.

  The inventor of the present application examined the reason why high saturation and high color rendering high-pressure sodium lamps are favorably used for lighting fresh food. Various factors such as correlated color temperature CCT, color rendering index CRI, and wavelength spectrum distribution can be considered as the reason. First, focused on correlated color temperature CCT. The reason is that there is a demand for vivid colors of red lines in lighting of fresh foods such as vegetables, bread and meat.

  The correlated color temperature of the high-saturation color-rendering high-pressure sodium lamp is usually around 2500K. On the other hand, with a conventional ceramic metal halide lamp, it is difficult to obtain the same correlated color temperature, and usually a higher correlated color temperature is obtained. The inventor of the present application considered creating a ceramic metal halide lamp capable of obtaining a correlated color temperature comparable to that of a high-saturation, high color rendering high-pressure sodium lamp. However, even if the desired correlated color temperature can be achieved, it is meaningless if the lamp life, the chromaticity deviation Duv, the color rendering index CRI, the light emission efficiency η, and the like deteriorate. Therefore, the inventors of the present application set the following goals.

  (1) Target correlated color temperature: about 2500K, that is, 2500K ± 10% (2250-2750K), preferably 2400-2600K.

  (2) Lamp life target: 15000 hours or more.

  (3) Target of chromaticity deviation Duv: −2 <Duv <+1. The color rendering index CRI and the luminous efficiency η are greater than or equal to predetermined values. The chromaticity deviation Duv represents a deviation from the black body locus (BBL) on the chromaticity diagram. The black body locus (BBL) on the chromaticity diagram represents the natural color of sunlight. Duv = 0 indicates that the chromaticity is on the black body locus (BBL).

  In order to achieve such a goal, the inventor of the present application diligently studied the additives to be sealed in the arc tube of the ceramic metal halide lamp, and made various combinations of additives and conducted experiments. As additives, rare earth metal iodides, alkali metal iodides, and alkaline earth metal iodides were used.

  In experiments conducted by the inventors of the present application, the rare earth metal iodides include iodides such as dysprosium Dy, holmium Ho, thulium Tm, and cerium Ce. Alkali metal iodides include iodides such as sodium Na and lithium Li. Alkaline earth metal iodides include iodides such as calcium Ca. Furthermore, in experiments conducted by the inventors of the present application, thallium Tl iodide is included as an additive. Indium, barium, etc. are not used. In the experiments conducted by the inventors, iodide was used as the halide, but other halides may be used.

In general, it is known that when sodium Na is added, the correlated color temperature decreases. However, in this embodiment, the red balance is adjusted by further adding lithium Li. The addition of dysprosium iodide DyI _3, but improves the color rendering, luminous efficiency is lowered, iodide holmium HoI ₃ and, that the addition of iodide thulium TmI _3, it is known that each luminous efficiency is improved . It is known that when cerium iodide CeI ₃ and thallium iodide TlI are added, the luminous efficiency increases and the numerical value of the chromaticity deviation Duv increases. It is known that the addition of calcium iodide CaI ₂ shifts the numerical value of the chromaticity deviation Duv, but the special color rendering index (red) R9 is improved.

  Generally, Na (for example, sodium and mercury amalgam) is used as an additive in a high-pressure sodium lamp, but sodium iodide NaI is used in a ceramic metal halide lamp. The saturated vapor pressures of liquid sodium and liquid sodium iodide are expressed by the following equations, respectively.

logP (Na) =-5269 (1 / T) +4.555 Equation 1
logP (NaI) =-8046 (1 / T) +5.084 Equation 2
P (Na) is the saturated vapor pressure [atm] of liquid sodium, and P (NaI) is the saturated vapor pressure [atm] of liquid sodium iodide. log is the common logarithm, and T is the absolute temperature [K].

  Using these equations, for example, the saturated vapor pressure P [atm] of liquid sodium and liquid sodium iodide at a temperature of 800 ° C. can be obtained. Substituting T = 800 ° C. = 1073 K into Equation 1 and Equation 2 results in P (Na) = 0.441 atm and P (NaI) = 0.00385 atm. The saturated vapor pressure P (NaI) of liquid sodium iodide at 800 ° C. is 1/100 or less of the saturated vapor pressure P (Na) of liquid sodium. Therefore, the amount of sodium iodide vaporized in the arc tube of the ceramic metal halide lamp is very small compared to the amount of sodium vaporized in the arc tube of the high-pressure sodium lamp.

  Therefore, the technique of enhancing the color rendering index CRI by increasing the absorption of the sodium emission line at 589 nm excessively and enhancing the color rendering index CRI, such as a high saturation high color rendering high-pressure sodium lamp, cannot be used with a ceramic metal halide lamp. Even if the absolute amount of sodium iodide to be encapsulated is increased, if a large amount of thallium iodide or rare earth iodide is encapsulated, blue to green light emission increases and the correlated color temperature CCT of the entire lamp does not decrease. There is also.

  Therefore, the inventors of the present application selected the following parameters by paying attention to the amount of sodium iodide in the additive.

The amount of rare earth metal iodide added is G (ReI ₃ ), the amount of alkali metal iodide added is G (AI), and the amount of alkaline earth metal iodide added is G (AeI ₂ ). . The amount of thallium iodide added is expressed as G (TlI), and the total amount of additives is expressed as G (total). The total amount G (total) of the additive is expressed by the following formula.

G (total) = G (ReI ₃ ) + G (AI) + G (AeI ₂ ) + G (TlI) Equation 3
Here, G (total), G (ReI ₃ ), G (AI), G (AeI ₂ ), and G (TlI) are masses per 1 cm ^{3 of} the arc tube volume, and the unit is [mg / cm ³ ].

The molar ratio of sodium iodide to the total number of moles of additive is M (NaI) [mol%], and the sum of the molar ratio of the rare earth metal iodide and the thallium iodide is M (ReI ₃ + TlI) [mol %]. Let α be the ratio of the molar ratio M (NaI) of sodium iodide to the sum M (ReI ₃ + TlI) of this molar ratio. α is represented by the following equation.

α = M (NaI) / M (ReI ₃ + TlI) Formula 4
FIG. 4A is a diagram showing the results of an experiment conducted by the inventors of the present application. The vertical axis represents the correlated color temperature, and the horizontal axis represents the ratio α represented by Equation 4. The target of the correlated color temperature, that is, about 2500 K ± 10% (2250 to 2750 K) is obtained when the ratio α is 4 <α <16. Further, the correlated color temperature is 2400 to 2600 K when the ratio α is 7 <α <13.

FIG. 4B is a diagram illustrating a result of an experiment performed by the inventors of the present application. The vertical axis represents the chromaticity deviation Duv, and the horizontal axis represents the sum M (ReI ₃ + TlI) [mol%] of the molar ratio of the rare earth metal iodide and the molar ratio of thallium iodide to the total number of moles of the additive. The target of the chromaticity deviation Duv, that is, Duv = −2 to 1 is when 2 mol% <M (ReI ₃ + TlI) <9 mol%.

  4A and 4B, the target of the correlated color temperature, that is, about 2500K ± 10% (2250-2750K), and the target of the chromaticity deviation Duv, that is, the condition that Duv is −2 to +1 are as follows. It is represented by the formula of

4 <M (NaI) / M (ReI ₃ + TlI) <16 Formula 5
2 mol% <M (ReI ₃ + TlI) <9 mol% Formula 6
The target of the correlated color temperature, 2400 to 2600 K, the target of the chromaticity deviation Duv, and the condition that Duv is −2 to +1 are expressed by the following equations.

表１において、M(TmI₃)、M(HoI₃)、M(TlI)、M(NaI)、M(CaI₂)、及び、M(LiI)は、それぞれ、ヨウ化ツリウムTmI₃、ヨウ化ホルミウムHoI₃、ヨウ化タリウムTlI、ヨウ化ナトリウムNaI、ヨウ化カルシウムCaI₂及びヨウ化リチウムLiIのモル比率(百分率)を表す。本願の発明者が行った実験では、発光管の添加物は、ヨウ化タリウムTlI、ヨウ化ナトリウムNaI、ヨウ化カルシウムCaI₂及びヨウ化リチウムLiIを含む。ナトリウムNaは橙色系、カルシウムCaは赤色系、リチウムLiは真紅色系に寄与する。ヨウ化ナトリウムNaI、ヨウ化カルシウムCaI₂及びヨウ化リチウムLiIをそれぞれ所定のモル比率にて添加することにより、所望の相関色温度が得られる。 7 <M (NaI) / M (ReI ₃ + TlI) <13 Formula 7
2 mol% <M (ReI ₃ + TlI) <9 mol% Formula 8
Table 1 shows the composition of the arc tube additive of the ceramic metal halide lamp used in the experiment conducted by the inventors of the present application. Here, conditions of five types of ceramic metal halide lamps that can achieve the target of the correlated color temperature and the target of the chromaticity deviation Duv are shown.

In Table 1, M (TmI ₃ ), M (HoI ₃ ), M (TlI), M (NaI), M (CaI ₂ ), and M (LiI) are respectively thulium iodide TmI ₃ and iodide. It represents the molar ratio (percentage) of holmium HoI ₃ , thallium iodide TlI, sodium iodide NaI, calcium iodide CaI ₂ and lithium iodide LiI. In experiments conducted by the inventors of the present application, the arc tube additive contains thallium iodide TlI, sodium iodide NaI, calcium iodide CaI ₂ and lithium iodide LiI. Sodium Na contributes to the orange system, calcium Ca contributes to the red system, and lithium Li contributes to the crimson system. By adding sodium iodide NaI, calcium iodide CaI ₂ and lithium iodide LiI in a predetermined molar ratio, a desired correlated color temperature can be obtained.

By adding thallium iodide TlI, the luminous efficiency increases, but the chromaticity deviation Duv increases. However, in this embodiment, by adding calcium iodide CaI _2, to suppress the increase of the chromaticity deviation Duv.

Further, the additive may include thulium iodide TmI ₃ as the rare earth metal iodide ReI _3, and may further include holmium iodide HoI ₃ . Luminous efficiency is improved by adding thulium iodide TmI ₃ and holmium iodide HoI ₃ , respectively.

The following knowledge is obtained from Table 1. According to the present embodiment, the arc tube additive includes sodium iodide NaI, calcium iodide CaI ₂ and lithium iodide LiI, and the molar ratio thereof is expressed as follows.

30 mol% <M (NaI) <70 mol% Formula 9
10 mol% <M (CaI ₂ ) <40 mol% Formula 10
10 mol% <M (LiI) <30 mol% Formula 11
Further, when the sum of the molar ratio of sodium iodide, the molar ratio of calcium iodide, and the molar ratio of lithium iodide is M (NaI + CaI ₂ + LiI), this value satisfies the following formula.

表３はこれらの５種のセラミックメタルハライドランプについて、相関色温度CCT、色度偏差Duv、平均演色評価数Ra、及び、発光効率ηを測定した結果を示す。平均演色評価数Raはいずれも９０より大きく、発光効率はいずれも７５lm/Wより大きかった。

次に、本願の発明者は、セラミックメタルハライドランプの発光管に封入する添加物をパラメータとして、ランプ寿命L[h]が１５０００時間以上となる条件を見出した。表４は、出願人が今までに開発してきたうち一部のランプ仕様を整理したものである。ここでは、No.11〜20の１０種のセラミックメタルハライドランプについてまとめた。

表４において、G(total)は、式３によって表される発光管容積１cm³当たりの添加物の総量である。G(ReI₃)は、発光管容積１cm³当たりの希土類金属ヨウ化物の添加量である。いずれも、単位は[mg/cm³]である。この結果から、ランプ寿命を長くするためには添加物総量及び希土類ヨウ化物の添加量を制限する必要があることが判る。ランプ寿命L[h]が１５０００時間より長いのは、試験番号No.16〜20である。以上の結果から、式５〜式１１の条件を有し、且つ、ランプ寿命L[h]が１５０００時間より長くなるためには、次の条件が必要である。 50mol% <M (NaI + CaI 2 + LiI) <96mol% formula 12
The numerical values in Table 2 are the values of α represented by Formula 4, the sum of the rare earth metal iodide molar ratio and the thallium iodide molar ratio M (ReI ₃ + TlI), for the additives shown in Table 1. 3 shows the results of calculating the total amount G (total) of additives per 1 cm ³ arc tube volume represented by ^{3 and} the rare earth metal iodide addition amount G (ReI ₃ ) per 1 cm ³ arc tube volume. As shown in Table 1, rare earth metal iodides ReI ₃ are thulium iodide TmI ₃ and holmium iodide HoI ₃ .

Table 3 shows the results of measuring the correlated color temperature CCT, the chromaticity deviation Duv, the average color rendering index Ra, and the luminous efficiency η for these five ceramic metal halide lamps. The average color rendering index Ra was greater than 90, and the luminous efficiency was greater than 75 lm / W.

Next, the inventor of the present application has found a condition that the lamp life L [h] is 15000 hours or longer with the additive enclosed in the arc tube of the ceramic metal halide lamp as a parameter. Table 4 summarizes some of the lamp specifications that the applicant has developed so far. Here, 10 types of ceramic metal halide lamps Nos. 11 to 20 are summarized.

In Table 4, G (total) is the total amount of additive per 1 cm ³ arc tube volume represented by Equation 3. G (ReI ₃ ) is the amount of rare earth metal iodide added per 1 cm ³ arc tube volume. In either case, the unit is [mg / cm ³ ]. From this result, it can be seen that it is necessary to limit the total amount of additive and the amount of rare earth iodide added in order to extend the lamp life. Test numbers No. 16 to 20 have a lamp life L [h] longer than 15000 hours. From the above results, the following conditions are necessary for satisfying the conditions of Expressions 5 to 11 and for the lamp life L [h] to be longer than 15000 hours.

G (total) <44 mg / cm ³ Formula 13
G (ReI ₃ ) <11 mg / cm ³ Formula 14
The ceramic metal halide lamp according to the present embodiment has been described above, but these are examples and do not limit the scope of the present invention. Additions, deletions, changes, improvements, and the like that can be easily made by those skilled in the art with respect to the present embodiment are within the scope of the present invention. The technical scope of the present invention is defined by the appended claims.

DESCRIPTION OF SYMBOLS 1 ... Ceramic metal halide lamp, 2 ... Arc tube, 4A, 4B ... Capillary, 5A, 5B ... Electrode, 6A, 6B ... Electrode assembly, 7A, 7B ... Power supply lead, 8A, 8B ... Metal foil, 9A, 9B ... External Terminal: 12 ... Base, 13 ... Outer sphere, 14 ... Stem, 15, 16 ... Post, 17A, 17B ... Support disk, 18 ... Translucent sleeve, 19A, 19B ... Nickel wire, 20 ... Getter, 13A ... Outer sphere Chip-off part, 13B ... Pinch seal part

Claims (6)

In a ceramic metal halide lamp having a light-emitting tube that includes a pair of electrodes and is formed of a light-transmitting ceramic, and a light-transmitting outer tube that houses the light-emitting tube,
The arc tube encloses a starting rare gas, mercury, and an additive. The additive includes thallium iodide TlI, sodium iodide NaI, calcium iodide CaI ₂ , lithium iodide LiI, and rare earth metal iodide. includes a compound ReI _3, further correlated color temperature 2250~2750K, 20~30W / cm ² is the wall load, configured to rated output is 35～400W, and,
The molar ratio of sodium iodide to the total number of moles of the additive is M (NaI) [mol%], and the sum of the molar ratio of the rare earth metal iodide ReI _{3 and} the molar ratio of thallium iodide TlI is M (ReI ₃ + TlI ) [mol%], the ceramic metal halide lamp characterized in that M (NaI) and M (ReI ₃ + TlI) satisfy the following formula.
4 <M (NaI) / M (ReI ₃ + TlI) <16
2 mol% <M (ReI ₃ + TlI) <9 mol% The ceramic metal halide lamp according to claim 1,
Wherein the total amount of the arc tube volume 1 cm ³ per additives G (total) [mg / cm 3], the amount per arc tube 1 cm ³ of the iodide of a rare earth metal contained in the additive G (ReI ₃₎ When [mg / cm ³ ], the ceramic metal halide lamp is characterized in that G (total) and G (ReI ₃ ) satisfy the following formula.
G (total) <44 mg / cm ³
G (ReI ₃ ) <11 mg / cm ³
3. The ceramic metal halide lamp according to claim 1, wherein the molar ratio M (NaI) of sodium iodide, the molar ratio M of calcium iodide (CaI ₂ ), and the molar ratio M of lithium iodide with respect to the total number of moles of the additive. A ceramic metal halide lamp characterized in that when the sum of (LiI) is M (NaI + CaI ₂ + LiI), the sum satisfies the following formula.
50mol% <M (NaI + CaI 2 + LiI) <96mol% The ceramic metal halide lamp according to any one of claims 1 to 3, wherein a molar ratio M (NaI) of sodium iodide, a molar ratio M (CaI ₂ ) of calcium iodide and iodide with respect to the total number of moles of the additive. A ceramic metal halide lamp characterized in that the molar ratio M (LiI) of lithium satisfies the following formula.
30 mol% <M (NaI) <70 mol%
10 mol% <M (CaI ₂ ) <40 mol%
10 mol% <M (LiI) <30 mol% In the ceramic metal halide lamp according to any one of claims 1 to 4,
The additive includes, as rare earth metal iodide, at least one of thulium iodide TmI ₃ , dysprosium Dy, holmium Ho, and cerium Ce iodide (thulium iodide TmI ₃ is essential). Characteristic ceramic metal halide lamp. In the ceramic metal halide lamp according to any one of claims 1 to 5,
The correlated color temperature of the arc tube is 2400-2600K, and the M (NaI) and M (ReI ₃ + TlI) satisfy the following formula.
7 <M (NaI) / M (ReI ₃ + TlI) <13

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