JP2010086739A - Low pressure discharge lamp, lighting system, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve strength of the sealed portion of a glass bulb, when using the glass bulb having a coefficient of thermal expansion within a range of not less than 8.0×10<SP>-6</SP>[K<SP>-1</SP>] and not more than 10.0×10<SP>-6</SP>[K<SP>-1</SP>]. <P>SOLUTION: This low pressure discharge lamp includes the glass bulb 101 having the coefficient of thermal expansion within a range of not less than 8.0×10<SP>-6</SP>[K<SP>-1</SP>] and not more than 10.0×10<SP>-6</SP>[K<SP>-1</SP>], an electrode 102 disposed in the inside of the glass bulb 101, and a lead wire 103 connected to the electrode 102 and sealed to at least one of the end parts of the glass bulb 101. An oxide film 105 is formed on the surface of the sealed portion 101a in the lead wire 103, and the thickness of the oxide film 105 has a distribution in which both end parts 105b, 105c are thicker than the center part 105a in the axial direction of the lead wire 103. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a low-pressure discharge lamp, an illumination device, and a liquid crystal display device.

FIG. 13 shows an enlarged cross-sectional view of a main part showing one end of a conventional low-pressure discharge lamp. The other end also has substantially the same configuration. A conventional low-pressure discharge lamp (hereinafter referred to as “lamp 1”) is a cold cathode fluorescent lamp composed of a discharge envelope (glass bulb) 2 made of hard glass, and the discharge envelope 2 has a phosphor 3 on its inner surface. The discharge envelope 2 is sealed, and the sealed gas component that emits ultraviolet light, the two or more hollow cathodes (electrodes) 4, the two or more through pins (lead wires) 5 and the through pins 5 withstand vacuum. It includes two or more glass-metal seals 6 that are bonded to the discharge envelope 2 with hermetic seals. Further, in the lamp 1, the penetrating pin 5 is made of molybdenum or a molybdenum alloy over at least the length of the glass-metal seal 6, and the hollow cathode 4 is made of a material of the group of molybdenum, molybdenum alloy, niobium, and niobium alloy. The glass in the region of the glass-metal seal 6 is at least partially made and has a coefficient of thermal expansion of 4.0 × 10 ⁻⁶ K ^{−1 to} 5.3 × 10 ⁻⁶ K ⁻¹ (20 ° C. to 300 ° C. ° C.) and, SiO _2: 55 wt% to 75 wt%, B ₂ O _3: 13 wt% to 25 wt%, Al ₂ O _3: 0 wt% to 10 wt%, alkali oxide: 5% to 12 wt% alkaline earth oxides: 0% to 3% by weight, ZrO _2: 0 wt% to 5 wt%, TiO _2: 0 wt% to 10 wt%, and the remainder of the oxide: 0% to 5 Having a composition by weight (eg patents) Reference 1 etc.).
JP 2004-356098 A

In recent years, due to the demand for lower lamp prices, hard glass (thermal expansion coefficient: 3.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 5.0 × 10 ⁻⁶ [K ^{− 1} ] instead of cheap glass (with a thermal expansion coefficient of 8.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 10.0 × 10 ⁻⁶ [K ⁻¹ ] or less) There are efforts to use it.

  When using soft glass as a material for the glass bulb, the inventors selected a lead wire material based on the lamp 1 so that the thermal expansion coefficient of the lead wire is close to the thermal expansion coefficient of the glass bulb, and prototyped the lamp. And various lamp performances were evaluated. However, in the case of soft glass, the strength of the sealed portion of the lead wire in the glass bulb (hereinafter referred to as the “sealed portion of the glass bulb”) is insufficient only by approximating the thermal expansion coefficient between the lead wire and the glass bulb. Met.

  In particular, low-pressure discharge lamps used for backlights and the like may be subject to a large load on the lead wires that may not be expected due to, for example, insertion into the backlight unit. There is a risk of damage due to the load on the lead wire. In recent years, high-level quality assurance is required, and in low-pressure discharge lamps, the sealing part of the glass bulb is the boundary that separates the inside and the outside of the glass bulb, and the reliability of its strength is required more severely. ing.

Therefore, in the low-pressure discharge lamp according to the present invention, when a glass bulb in the range of 8.0 × 10 ⁻⁶ [K ⁻¹ ] to 10.0 × 10 ⁻⁶ [K ⁻¹ ] is used, It aims at improving the intensity | strength of the sealing part of a valve | bulb.

  Another object of the illumination device and the liquid crystal display device according to the present invention is to prevent the low-pressure discharge lamp from being damaged by an impact caused by movement.

In order to solve the above problems, the low-pressure discharge lamp according to the present invention has a coefficient of thermal expansion in the range of 8.0 × 10 ⁻⁶ [K ⁻¹ ] to 10.0 × 10 ⁻⁶ [K ⁻¹ ]. A low-pressure discharge lamp having an inner glass bulb, an electrode disposed inside the glass bulb, and a lead wire connected to the electrode and sealed at at least one end of the glass bulb, An oxide film is formed on the surface of the sealing portion of the lead wire, and the film thickness of the oxide film has a distribution such that both end portions are thicker than the center portion in the line axis direction of the lead wire. It is characterized by.

  In the low-pressure discharge lamp according to the present invention, it is preferable that the thickness of the oxide film has a distribution that increases in thickness from the center to both ends in the direction of the axis of the lead wire.

  In the low-pressure discharge lamp according to the present invention, it is preferable that the oxide film has a thickness of 1.0 [μm] to 3.0 [μm] at both ends.

  In the low-pressure discharge lamp according to the present invention, it is preferable that the lead wire is formed of an alloy of iron and nickel, and the oxide film is formed of iron oxide.

  In the low-pressure discharge lamp according to the present invention, the electrode has a bottomed cylindrical shape, and a difference between an inner diameter of the glass bulb and an outer diameter of the electrode is within 4 mm, The length of the lead wire in the linear axis direction is preferably in the range of 7 [mm] to 20 [mm].

  An illumination device according to the present invention includes the low-pressure discharge lamp.

  The liquid crystal display device according to the present invention includes the illumination device.

The low-pressure discharge lamp according to the present invention uses a glass bulb in a range of 8.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 10.0 × 10 ⁻⁶ [K ⁻¹ ] or less. The strength of the sealing part can be improved.

  In addition, the illumination device and the liquid crystal display device according to the present invention can prevent the cold cathode discharge lamp from being damaged by an impact caused by movement.

(First embodiment)
FIG. 1A is a cross-sectional view including the tube axis X ₁₀₀ of the low-pressure discharge lamp according to the first embodiment of the present invention, and FIG. 1B is an enlarged cross-sectional view of a main part of A portion in FIG. Respectively. The low-pressure discharge lamp 100 (hereinafter referred to as “lamp 100”) according to the first embodiment of the present invention is a cold cathode fluorescent lamp.

  The lamp 100 includes a glass bulb 101, an electrode 102 disposed inside the glass bulb 101, and a lead wire 103 connected to the electrode 102 and sealed at at least one end of the glass bulb 101.

The glass bulb 101 has a straight tube shape, and has a substantially circular cross section cut perpendicular to the tube axis. The glass bulb 101 has, for example, an outer diameter of 4.0 [mm], an inner diameter of 3.0 [mm], and an overall length of 1026 [mm], and the material has a thermal expansion coefficient of 8.0 × 10 ^−6. It is a soft glass within the range of [K ⁻¹ ] to 10.0 × 10 ⁻⁶ [K ⁻¹ ]. The dimensions of the lamp 100 shown below are values corresponding to the dimensions of the glass bulb 101 having an outer diameter of 4.0 [mm] and an inner diameter of 3.0 [mm]. In the case of a cold cathode fluorescent lamp, the inner diameter is 1.4 [mm] to 7.0 [mm], and the wall thickness is within the range of 0.2 [mm] to 0.6 [mm]. The total length is preferably 1500 [mm] or less. These values are examples and are not limited to these.

  Mercury is sealed in the glass bulb 101 at a predetermined ratio to the volume of the glass bulb 101, for example, 0.6 [mg / cc], and a rare gas is sealed at a predetermined sealing pressure, for example, 40 [Torr. ] Enclosed. As the rare gas, a mixed gas of argon and neon (molar ratio: Ar = 10 [%], Ne = 90 [%]) is used.

A phosphor layer 104 is formed on the inner surface of the glass bulb 101. The phosphor particles used for the phosphor layer 104 are, for example, red phosphor particles (Y ₂ O ₃ : Eu ³⁺ ), green phosphor particles (LaPO ₄ : Ce ³⁺ , Tb ³⁺ ), and blue phosphor particles ( BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ).

Further, between the inner surface of the glass bulb 101 and the phosphor layer 104, for example, yttrium oxide (Y ₂ O ₃ ), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), oxide A protective film (not shown) of a metal oxide such as titanium (TiO ₂ ) may be provided.

  Inside the both ends of the glass bulb 101, for example, one bottomed cylindrical electrode 102 made of nickel (Ni) is disposed. Specifically, the electrodes 102 are arranged in a state in which the opening side is directed to the central portion side of the glass bulb 101. The dimensions of each part of the electrode 102 are, for example, an electrode length of 8.2 [mm], an outer diameter of 2.70 [mm], an inner diameter of 2.40 [mm], and a wall thickness of 0.15 [mm].

  Note that an emitter (not shown) may be attached to the surface of the electrode 102. In this case, the starting voltage of the lamp 100 can be suppressed. In particular, a cesium compound may be attached to the surface of the electrode 102. In this case, the dark start characteristics of the lamp 100 can be improved.

  One end of a lead wire 103 is connected to the electrode 102. Specifically, the outer bottom surface of the electrode 102 and one end surface of the lead wire 103 are connected. This connection is performed by resistance welding or laser welding, for example. Even if an insertion member is inserted between the outer bottom surface of the electrode 102 and one end surface of the lead wire 103 in order to increase the connection strength between the electrode 102 and the lead wire 103 by resistance welding or laser welding. Good. If the strength of resistance welding or laser welding is increased or the welding time is lengthened in order to increase the connection strength, the material of the lead wire 103 diffuses to the bottom surface of the electrode 102 and the amount of diffusion is large. The inner bottom surface of the electrode 102 is easily sputtered by reaching the inner bottom surface. Therefore, a material having the same melting point as that of the electrode 102 or a lower melting point than the electrode 102 is used as an insertion member, and is sandwiched between the outer bottom surface of the electrode 102 and one end surface of the lead wire 103, thereby being interposed by resistance welding or laser welding. By melting the insertion member and connecting the bottom surface of the electrode 102 and one end surface of the lead wire 103, the connection strength can be increased.

  An oxide film 105 is formed on the surface of the sealing portion of the lead wire 103. The thickness of the oxide film 105 has a distribution such that both ends are thicker than the center in the direction of the axis of the lead wire 103. That is, as shown in FIG. 1B, the thickness of the oxide film 105 is slightly uneven in the axial direction of the lead wire 103 as compared to the thickness of the central portion 105a, but the end portion on the electrode side. The film thickness of 105b (hereinafter simply referred to as “one end portion 105b”) and the end portion 105c opposite to the electrode side (hereinafter simply referred to as “other end portion 105c”) are thicker. As shown in FIG. 2, the “sealed portion of the lead wire” in the present invention is a portion of the lead wire 103 that is located inside the glass, and is the outer end surface 101b and the inner end surface 101c of the glass bulb 101. It is the part sandwiched between.

  The “distribution of the thickness of the oxide film” was obtained by the following procedure.

  (1) Cut the lead wire substantially perpendicularly to the line axis at 10 [locations] that are spaced apart at substantially equal intervals in the longitudinal direction of the sealing portion.

  (2) Measure the thickness of the oxide film at arbitrary 3 [locations] that are separated at approximately equal intervals in each cross section, and calculate the average value of the thickness of the 3 [location] oxide films.

  According to the above procedure, the thickness distribution of the oxide film can be obtained from the thickness of the oxide film at 10 [locations] spaced at substantially equal intervals in the longitudinal direction of the sealing portion in the lead wire.

  Note that the measurement was performed by SEM under the condition of a magnification of 1000 [times].

  As shown in FIG. 2, the central portion refers to a substantially middle point between the outer end surface 101 b and the inner end surface 101 c of the glass bulb 101. Further, the one end portion means a position that is l / 20 [mm] away from the inner end surface of the glass bulb toward the other end portion side, and the other end portion refers to the one end portion side from the outer end surface of the glass bulb. / 20 [mm] up to a position away.

  The lead wire 103 is, for example, a joint consisting of an internal lead wire 103a made of an alloy of iron and nickel and an external lead wire 103b made of nickel. The wire diameter of the internal lead wire is, for example, 0.8 [mm], the total length is 3.4 [mm], the wire diameter of the external lead wire is, for example, 0.6 [mm], and the total length is 10.6 [mm]. . The internal lead wire 103a and the external lead wire 103b are connected by, for example, laser welding or resistance welding.

  The lead wire 103 is not divided into an internal lead wire and an external lead wire, and may be a single wire made of an alloy of iron and nickel, for example.

  The lead wire 103 is preferably formed of an alloy of nickel of 50 [wt%] or more and the remainder of iron. In this case, distortion of the sealing part of the glass bulb 101 can be reduced.

  Further, the lead wire 103 is more preferably formed of an alloy of nickel exceeding 50 [wt%] and the remainder being iron. In this case, the distortion of the sealing part of the glass bulb 101 can be further reduced.

  Furthermore, the lead wire 103 is more preferably formed of an alloy of 48 [wt%] iron and 52 [wt%] nickel. In this case, the distortion of the sealing part of the glass bulb can be further reduced. It is particularly suitable when the glass bulb 101 is lead-free glass.

  Further, the glass bulb 101 at the portion sealed with the lead wire is formed of a glass bead (not shown). In this case, the glass bead is preferably formed of a glass material having a thermal expansion coefficient that is the same as or close to that of the other part of the glass bulb 101. In addition, you may seal by the pinch seal method etc., without using a glass bead, for example.

(Experiment 1)
The inventors conducted an experiment in order to confirm that the lead wire 103 of the lamp 100 is not peeled off from the sealing portion 101a of the glass bulb 101 (high adhesion). Even if the glass bulb appears to be sealed in appearance, peeling may occur, and peeling cannot be visually confirmed. Therefore, an oxidation test by heating was performed. If there is a peeled portion, since the glass and the sealing wire are not in close contact with each other, the sealing wire is oxidized when heated in a furnace.

As an example, the experimental sample is provided with an oxide film on the sealed portion of the lead wire, the tube outer diameter is 4.0 [mm], the tube inner diameter is 3.0 [mm], and the length is 1026 [mm]. A low-pressure discharge lamp consisting of a glass bulb was prepared. Each of the lamps was cut at a position of 50 [mm] from both ends, and used as an experimental sample of the sealing portion. Each lamp has two sealing portions, a first sealing side and a second sealing side, based on the order in which the sealing portions are sealed during lamp manufacture. 10 [pieces] of lamps were prepared, and a total of 20 [pieces] including 10 [pieces] of the first sealing side and 10 [pieces] of the second sealing side were prepared. Specifically, a glass bulb having a thermal expansion coefficient of 9.4 × 10 ⁻⁶ [K ⁻¹ ] and a sealing portion made of glass beads is used, and films at one end and the other end of the lead wire oxide film are used. An example in which the thickness is larger than the thickness of the central portion was taken as an example. In addition, the lead wire used was an internal lead wire made of an alloy of iron and nickel and an external lead wire made of nickel.

For comparison, Comparative Example 1 has a configuration substantially the same as that of the example except that no oxide film is formed on the surface of the lead wire. Further, the glass bulb has substantially the same configuration as Comparative Example 1 except that the glass bulb is formed of hard glass having a thermal expansion coefficient of 4.0 × 10 ⁻⁶ [K ⁻¹ ] and the internal lead wire is made of tungsten. What it has was made into the comparative example 2.

  First, about 5 [pieces] each of the first sealing side and 5 [pieces] of the second sealing side, which are half of each experimental sample, were used as the experimental samples before the heat treatment.

  Further, among each experimental sample, the remaining 5 [pieces] for the first sealing side and 5 [pieces] for the second sealing side were each heated in a heating furnace at 450 [° C.] for about 2 [h]. And after taking out from the furnace and cooling to room temperature, the glass bulb | sheet was peeled from the lead wire and it was set as the experimental sample after heat processing.

And the length of the sealing part in the axis direction of each lead wire was measured for the experimental sample before the heat treatment and the experimental sample after the heat treatment, respectively. In addition, the length of the sealing part in the linear axis direction of the lead wire of the sample before heat processing measured the distance of the part which the glass bulb | stick contact | adhered in appearance. A microscope was used to measure the distance. Moreover, the distance in which the oxidation progressed was measured for the sealing portion in the linear axis direction of the lead wire after the heat treatment, and this was used as the peeling progress distance. This is because if the peeling occurs, the oxidation of the portion proceeds, and the oxidation progressing portion is considered as the peeling progressing portion. However, in the case of the example, since an oxide film (FeO or Fe ₃ O ₄ : black) was originally formed on the sealing portion, a change in the oxidation state was observed. Since the heating is performed in a normal air atmosphere, iron (Fe) contained in the lead wire is oxidized to become trivalent iron oxide (Fe ₂ O ₃ : red) and discolored.

  Subsequently, in each experimental sample, the sample before the heat treatment is compared with the sample after the heat treatment, and the length of the sealed portion of the sample after the heat treatment in the direction of the axis of the lead wire is shorter The symbol “x” indicates that the sample before the heat treatment and the sample after the heat treatment have the same or almost the same length of the sealed portion in the direction of the axis of the lead wire. In addition, the case where it is substantially the same is a case where the difference of the length before heat processing and after heat processing is less than +/- 0.1 [mm].

  The results of the experiment are shown in Table 1.

  As shown in Table 1, in Comparative Example 1, since there is a brown portion on the surface of the sealing portion of the glass bulb in the lead wire, it can be seen that the glass bulb has been peeled off from the lead wire. . This is a color in which iron is oxidized in an alloy of iron and nickel. Specifically, it was found that the peeling was about 0.2 [mm] on average.

  Moreover, since the comparative example 2 has the brown part in the surface of the sealing part of the glass bulb in a lead wire, it turns out that the glass bulb has peeled from the lead wire. This is an oxidized color of tungsten. Specifically, it was found that peeling was about 0.2 [mm] to 0.4 [mm].

  On the other hand, in Example 1, since the surface of the sealing part of the glass bulb in the lead wire has no discolored part before and after the heat treatment, it can be seen that the glass bulb does not peel from the lead wire.

  That is, in the example, the lead wire and the glass bulb are in close contact with each other at one end and the other end with respect to Comparative Examples 1 and 2, and the lead wire is not peeled off from the sealing portion of the glass bulb. In addition, even in a state where no load was applied, it was found that the adhesiveness of the sealing portion was higher than those of Comparative Examples 1 and 2 in the example.

(Experiment 2)
Next, in order to compare the sealing strength between the lead wire and the bead glass, the inventors first conducted an experiment to compare the tensile strength.

  As the experimental samples, 10 [pieces] were prepared as experimental samples, each of an example having substantially the same configuration as that of Experiment 1 and Comparative Examples 1 and 2.

  In the experiment, as shown in FIG. 3, the tensile strength was measured using a measuring jig 106. The measuring jig 106 includes a fixing unit 107 that fixes the lead wire 103, a gripping unit 108 that hooks and grips the glass bulb, a measuring unit 109 that digitizes the tensile strength, and a connecting unit that connects the gripping unit and the measuring unit. 110. The measurement unit 109 was an IMADA digital force gauge ZP-500N manufactured by Imada Co., Ltd. The measurement was performed by pulling the measurement unit in the direction opposite to the lead wire and measuring the numerical value indicated by the measurement unit 109 when the glass bulb 101 was cracked.

  The experimental results of Experiment 2 are shown in Table 2. The tensile strength in Table 2 shows an average value of 10 [pieces] in each experimental sample.

  From Table 2, it can be seen that the tensile strength of the example is dramatically improved as compared with Comparative Examples 1 and 2.

  The bonding force between the lead wire and the oxide film is stronger than the bonding force between the oxide film and the glass bulb. This can also be confirmed from the fact that, in Experiment 1, when the glass bulb was peeled from the lead wire, the oxide film remained on the surface of the lead wire.

  When the lead wire is pulled in the direction of the wire axis, the force pulling the lead wire is transmitted to the glass bulb through the oxide film. In the case of Comparative Example 1, the contact surface between the oxide film and the glass bulb is parallel to the direction in which the lead wire is pulled. It has become. On the other hand, in the case of Examples 1 to 3, there is a portion where the contact surface between the oxide film and the glass bulb is not parallel to the force pulling the lead wire, and the stress is dispersed. Since this part plays a role of suppressing the shift between the oxide film and the glass bulb, it is difficult for a crack to enter.

  That is, in the example, the film thickness of the portion sealed to the glass bulb 101 in the oxide film 105 is such that at least one end is thicker than the center in the direction of the axis of the lead wire 103. It was confirmed that the tensile strength was stronger than those of 2 and 2.

(Experiment 3)
Next, the inventors performed an impact test in order to confirm whether or not the strength when an impact is applied to the sealing portion is improved.

  As experimental samples, 10 lamps of Examples and Comparative Examples 1 and 2 having substantially the same configuration as Experiment 1 were prepared.

  A diagram showing an outline of the experimental jig 111 is shown in FIG. As shown in FIG. 4, each experimental sample 112 was held on the glass plate 113 at a position of 250 [mm] from the tube end of the glass bulb 101. (1) The lead wire 103 on the end side of the held position is lifted to the side opposite to the glass plate 113. (2) The glass bulb 101 is knocked against the glass plate 113 with the end of the glass bulb 101 being separated from the glass plate 113 by 10 [mm]. The operations (1) and (2) were repeated 10 times for each experimental sample. In this test, the electrode vibrates due to the collision vibration, and stress is applied to the electrode side of the sealing portion 101a of the glass bulb 101 to forcibly cause peeling.

  When the helium leak test was conducted after the test, no leakage of the inclusions was observed in all of the Examples and Comparative Examples 1 and 2.

(Experiment 4)
In Experiment 3, since there was no difference between Example and Comparative Examples 1 and 2, the inventors conducted a more severe test. Specifically, after performing the impact test of Experiment 3, a load test was additionally performed and a leak test was performed.

  An outline of the load test is shown in FIG. The experimental jig 114 includes a fixing base for fixing the lamp 115 of the experimental sample, a weight 116 for applying a load to the lead wire 103 of the lamp 115, and a connecting portion 117 for connecting the lead wire 103 and the weight 116. Has been.

  As experimental samples, 10 lamps of Examples and Comparative Examples 1 and 2 having substantially the same configuration as Experiment 1 were prepared.

  For each experimental sample, after performing the impact test of Experiment 3, it was fixed to a fixed base, and the state of each experimental sample when the weight 116 was set to 800 [g], 1800 [g], and 2800 [g] was observed. . This test is a test in which the electrode side in the sealing portion of the glass bulb is forcibly peeled in the test of Experiment 3 and then the opposite side in the tube axis direction of the glass bulb is also forcibly peeled off. In addition, during the test, not only the sealed part but the glass bulb itself was broken, and the result is also described. A helium leak test was carried out on those that were not damaged, and the presence or absence of leakage of the inclusion was inspected.

  The experimental results are shown in Table 3.

  As shown in Table 3, in the example and the comparative example 1, when the weight was set to 1800 [g], the glass bulb was not broken and the leakage of the inclusion was not caused. On the other hand, in Comparative Example 2, when the weight was set to 1800 [g], the glass bulb did not break. However, in 3 [out of 8], leakage of the inclusion occurred. I found out.

  In this example and the comparative example 1, since the glass bulb is soft glass, the glass bulb itself absorbs the load applied to the sealing portion of the glass bulb as compared with the case where the glass bulb of the comparative example 2 is hard glass. Because it can.

  Further, in the example, when the weight was set to 2800 [g], breakage of the glass bulb occurred at 1 [out of 8]. For 7 [books] that were not damaged, there was no leakage of the glass bulb. On the other hand, in Comparative Example 1, the glass bulb was broken at 5 [11] out of 11 [books], and the leakage of the inclusion occurred at 1 [of 6] [others]. I understood it.

  This is because in the embodiment, an oxide film is formed on the surface (especially, both ends) of the sealing portion in the lead wire, and the sealing strength is improved. Furthermore, since the thickness of the oxide film is thicker at both ends than the center in the direction of the line axis of the lead wire, as compared with the case where no oxide film is formed as in Comparative Example 1, It is presumed that the contact area with the glass bulb can be increased and the stress applied from the lead wire to the sealing portion of the glass bulb can be dispersed. Further, in Comparative Example 2, it was found that the glass bulb was broken in 2 [out of 8], and the leakage of the inclusion occurred in 5 [out of 6]. It was.

  Furthermore, it is preferable that the film thickness of the oxide film increases in the direction of the axis of the lead wire from the center to both ends. In this case, for example, it can be manufactured by locally heating the central portion of the glass bead with a gas burner or the like, and the manufacture is easy.

  The oxide film 105 preferably has a maximum thickness of 1.0 [μm] to 3.0 [μm] at both ends. If the maximum thickness at both ends is too thick, voids may be generated inside the oxide film during the formation of the oxide film, making it difficult to form the oxide film. This is because it is difficult to form a thin film stably if the film is too thin.

Experiments 1 to 4 were performed for one type of discharge lamp, and these experimental results indicate that the thermal expansion coefficient is 8.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 10.0 × 10 ⁻⁶ [K. ^-1 ] An oxide film is formed on the glass bulb in the following range and on the surface of the sealing portion of the lead wire, and the thickness of the oxide film is at least one of the central portion in the direction of the axis of the lead wire. If the end portion is thicker, the effect of the present invention is considered to be obtained compared to other cold cathode discharge lamps using soft glass, regardless of the material and size of the discharge lamp.

  Conventionally, a low-pressure discharge lamp is incorporated in a lighting device after its lead wire is soldered to a power supply lead wire and the end of the low-pressure discharge lamp is covered with a rubber bush. However, in recent years, in order to simplify the assembling process into the lighting device, a method has been adopted in which the lead wire of the low-pressure discharge lamp is directly fitted into the connector of the lighting device without soldering or a rubber bush. That is, the load applied in the direction perpendicular to the wire axis of the lead wire is larger than that of the conventional lighting device. For this reason, the lead wire of a low-pressure discharge lamp is required to have an improved strength when a force in a direction perpendicular to the lead wire axis is applied.

  For example, as shown in FIG. 6, in the case of the low pressure discharge lamp 120 having the base 119 at the end of the glass bulb, the base 119 is electrically and mechanically connected to the lead wire 103. Specifically, the base includes a body portion 119a that covers an end portion of the glass bulb, and an extending portion 119b that extends from one end of the body portion 119a and is electrically and mechanically connected to the lead wire 103. ing. When such a low-pressure discharge lamp 120 is incorporated in a lighting device, when the base 119 is inserted into a fuse socket (not shown), a load applied to the base 119 is applied as a force acting in a direction perpendicular to the lead wire 103. . That is, the present invention is particularly effective for the low-pressure discharge lamp 120 having the base 119 at the end of the glass bulb.

  Further, in order to suppress sputtering due to the discharge of the electrode, in a low-pressure discharge lamp using a bottomed cylindrical electrode, the difference between the inner diameter of the glass bulb and the outer diameter of the electrode has been reduced. In recent years, an attempt has been made to increase the length of the electrode in order to suppress the sputtering of the electrode. However, if the length of the electrode is increased while keeping the difference between the inner diameter of the glass bulb and the outer diameter of the electrode small, the weight of the electrode increases and the load on the sealing portion of the glass bulb also increases. .

  Therefore, in the present invention, the electrode has a bottomed cylindrical shape, and the difference between the inner diameter of the glass bulb and the outer diameter of the electrode is within 4 mm, and the length of the lead wire in the electrode in the axial direction is This is particularly effective when the thickness is in the range of 7 [mm] to 20 [mm]. In this case, the strength of the sealing portion between the lead wire and the glass bulb can be improved while suppressing sputtering of the electrode.

  Further, according to the present invention, the electrode has a bottomed cylindrical shape, and the difference between the inner diameter of the glass bulb and the outer diameter of the electrode is within 3 [mm], and the length of the lead wire in the electrode in the axial direction This is particularly effective when the thickness is in the range of 7 [mm] to 20 [mm]. In this case, sputtering of the electrode can be further suppressed.

As described above, according to the configuration of the cold cathode discharge lamp 100 according to the first embodiment of the present invention, the thermal expansion coefficient is 8.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 10.0 × 10 ⁻⁶ [ K ⁻¹ ] When a glass bulb in the following range is used, the strength of the sealed portion between the lead wire and the glass bulb can be improved.

(Second Embodiment)
FIG. 7 shows a cross-sectional view including the tube axis X ₂₀₀ of the discharge lamp according to the second embodiment of the present invention. As shown in FIG. 7, a low-pressure discharge lamp 200 (hereinafter simply referred to as “lamp 200”) according to the second embodiment of the present invention has an external electrode 201 on one outer surface and one inside the other end. This is an internal / external electrode fluorescent lamp having an internal electrode 103.

  The lamp 200 has an external electrode 201 on the outer surface of one end thereof, and has substantially the same configuration as that of the low-pressure discharge lamp 100 according to the first embodiment of the present invention except for the configuration associated therewith. Therefore, the external electrode 201 and the configuration accompanying it will be described in detail, and the other points will be omitted.

  The external electrode 201 is made of, for example, solder and is formed so as to cover the outer peripheral surface of one end of the glass bulb.

  The external electrode 201 may be formed by applying silver paste to the entire circumference of the electrode forming portion of the glass bulb 101, or a metal cap may be placed on the end of the glass bulb 101. Further, an aluminum metal foil may be pasted so as to cover the entire outer peripheral surface of the glass bulb 101 with a conductive adhesive (not shown) in which metal powder is mixed with silicone resin. . In addition, in a conductive adhesive, you may use a fluororesin, a polyimide resin, or an epoxy resin instead of a silicone resin.

Although not shown in FIG. 7, a protective film of, for example, yttrium oxide (Y ₂ O ₃ ) may be provided on the inner surface of the glass bulb 101 and in the region where the external electrode 201 is formed. By providing the protective film, it is possible to prevent glass scraping and pinholes caused by mercury ions bombarding the portion of the glass bulb 101.

The protective film may be made of metal oxide such as silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zinc oxide (ZnO), titania (TiO ₂ ), for example, instead of yttrium oxide. In particular, when the protective film is formed of yttrium oxide or silica, mercury hardly adheres to the protective film, and mercury consumption is low.

  However, the protective film is not an essential component in the present invention and may not be formed at all, or may be formed over the entire inner surface of the glass bulb 101.

As described above, according to the configuration of the cold cathode discharge lamp 200 according to the second embodiment of the present invention, the thermal expansion coefficient is 8.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 10.0 × 10 ⁻⁶ [ K ⁻¹ ] When a glass bulb in the following range is used, the strength of the sealed portion between the lead wire and the glass bulb can be improved.

(Third embodiment)
FIG. 8 shows a cross-sectional view including a tube axis of a discharge lamp 300 (hereinafter simply referred to as “lamp 300”) according to a third embodiment of the present invention. As shown in FIG. 8, the lamp 300 is a hot cathode fluorescent lamp, and includes a glass bulb 301 and an electrode mount 302.

  The glass bulb 301 has, for example, a total length of 1010 [mm], an outer diameter of 18 [mm], and a wall thickness of 0.8 [mm], and electrode mounts 302 are sealed at both ends thereof.

  A phosphor layer 104 is formed on the inner surface of the glass bulb 301. Mercury (for example, 4 [mg] to 10 [mg]) is sealed inside the glass bulb 301, and argon is used as a buffer gas. A mixed gas of (Ar) and krypton (Kr) (for example, a mixed gas having a partial pressure ratio of Ar of 50 [%] and Kr of 50 [%]) is sealed at a sealed gas pressure of 600 [Pa], for example.

  As shown in FIG. 8, the electrode mount 302 includes an electrode 303 that is a filament coil made of tungsten, a pair of lead wires 304 that support the electrode 303, and a bead glass 305 that fixes and supports the pair of lead wires 304. It consists of.

  A part of the lead wire 304 is sealed to the end of the glass bulb 301 in the electrode mount 302, specifically, a part extending from the bead glass 305 to the side opposite to the electrode 303. . An oxide film 105 is formed on the surface of the sealing portion of the lead wire as in the first embodiment of the present invention. The electrode mount 302 is sealed to the glass bulb 301 by, for example, a pinch seal method.

  An exhaust pipe remaining portion 306 is attached together with the electrode mount 302 to at least one end of the glass bulb 301. This exhaust pipe remaining portion 306 is used when exhausting the inside of the arc tube 301 or sealing the above-mentioned sealed gas or the like after the electrode mount 302 is sealed. When the sealing is completed, for example, chip-off sealing is performed at a portion of the exhaust pipe remaining portion 306 located outside the arc tube 301.

As described above, according to the configuration of the cold cathode discharge lamp 300 according to the third embodiment of the present invention, the thermal expansion coefficient is 8.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 10.0 × 10 ⁻⁶ [ K ⁻¹ ] When a glass bulb in the following range is used, the strength of the sealed portion between the lead wire and the glass bulb can be improved.

(Fourth embodiment)
FIG. 9 shows an exploded perspective view of a lighting apparatus 400 according to the fourth embodiment of the present invention. The illumination device 400 according to the fourth embodiment of the present invention is a direct-type backlight unit, and includes a rectangular parallelepiped housing 401 having one open surface and a plurality of lamps housed in the housing 401. 100, a pair of sockets 402 for electrically connecting the lamp 100 to a lighting circuit (not shown), and optical sheets 403 covering the opening of the housing 401. The lamp 100 is the discharge lamp 100 according to the first embodiment of the present invention.

  The casing 401 is made of, for example, polyethylene terephthalate (PET) resin, and a reflective surface 404 is formed by depositing a metal such as silver on the inner surface thereof. In addition, as a material of the housing | casing 401, you may comprise by metal materials, such as materials other than resin, for example, aluminum, a cold rolled material (for example, SPCC). Further, as the inner reflection surface 404, other than the metal vapor deposition film, for example, a reflection sheet whose reflectance is increased by adding calcium carbonate, titanium dioxide or the like to polyethylene terephthalate (PET) resin is used. May be.

  Inside the casing 401, a socket 402, an insulator 405, and a cover 406 are disposed. Specifically, the sockets 402 are provided at predetermined intervals in the lateral direction (vertical direction) of the housing 401 corresponding to the arrangement of the lamps 100. The socket 402 is obtained by processing a plate material made of, for example, stainless steel or phosphor bronze, and has a fitting portion 402a into which the external lead wire 104b is fitted. Then, the lead wire 103 is fitted by being elastically deformed so as to expand the fitting portion 402a. As a result, the lead wire 103 fitted into the fitting part 402a is pressed by the restoring force of the fitting part 402a and is difficult to come off. Accordingly, the lead wire 103 can be easily fitted into the fitting portion 402a, but can be made difficult to come off.

  The socket 402 is covered with an insulator 405 so as not to short-circuit between adjacent sockets 402. The insulator 405 is made of, for example, polyethylene terephthalate (PET) resin. Note that the insulator 405 is not limited to the above structure. Since the socket 402 is in the vicinity of the electrode 102 that becomes relatively hot during operation of the lamp 100, the insulator 405 is preferably made of a heat resistant material. As a material of the heat-resistant insulator 405, for example, polycarbonate (PC) resin, silicon rubber, or the like can be used.

  A lamp holder 407 may be provided inside the housing 401 at a place as necessary. The lamp holder 407 that fixes the position of the lamp 100 inside the housing 401 is, for example, polycarbonate (PC) resin, and has a shape that follows the outer shape of the lamp 100. “A place where necessary” means that the deflection of the lamp 100 is caused when the lamp 100 has a long length exceeding, for example, 600 [mm], as in the vicinity of the central portion of the lamp 100 in the longitudinal direction. It is a place necessary to eliminate.

  The cover 406 divides the socket 402 from the space inside the housing 401. The cover 406 is made of, for example, polycarbonate (PC) resin, keeps the periphery of the socket 402 warm, and highly reflects at least the surface on the housing 401 side. By reducing the brightness, a decrease in luminance at the end of the lamp 100 can be reduced.

  The opening of the housing 401 is covered with a light-transmitting optical sheet 403 and is sealed so that foreign matter such as dust and dust does not enter inside. The optical sheet 403 is formed by laminating a diffusion plate 408, a diffusion sheet 409, and a lens sheet 410.

  The diffusion plate 408 is a plate-like body made of, for example, polymethyl methacrylate (PMMA) resin, and is disposed so as to close the opening of the housing 401. The diffusion sheet 409 is made of, for example, a polyester resin. The lens sheet 410 is, for example, a laminate of an acrylic resin and a polyester resin. These optical sheets 403 are disposed so as to be sequentially superimposed on the diffusion plate 408.

  As described above, according to the configuration of the illumination device 400 according to the fourth embodiment of the present invention, it is possible to prevent the cold cathode discharge lamp from being damaged by an impact caused by movement.

(Fifth embodiment)
FIG. 10 shows a partially cutaway perspective view of a lighting apparatus according to the fifth embodiment of the present invention. An illuminating device 500 (hereinafter referred to as “illuminating device 500”) according to a fifth embodiment of the present invention is an edge light type backlight unit, and includes a reflector 501, a lamp 100, a socket (not shown), and a light guide plate. 502, a diffusion sheet 503, and a prism sheet 504.

  The reflection plate 501 is disposed so as to surround the periphery of the light guide plate 502 except the liquid crystal panel side (arrow Q), and the side surface covering the bottom surface portion 501b covering the bottom surface and the side surface excluding the side where the lamp 100 is disposed. Part 501a and a curved lamp side part 501c covering the periphery of the lamp 100, and reflects light emitted from the lamp from the light guide plate 502 to the liquid crystal panel (not shown) side (arrow Q). . Moreover, the reflecting plate 501 is made of, for example, a film-like PET deposited with silver or a laminate of a metal foil such as aluminum.

  The socket has substantially the same configuration as the socket 402 used in the lighting device 400 according to the fourth embodiment of the present invention. In FIG. 11, the end of the lamp 100 is omitted for convenience of illustration.

  The light guide plate 502 is for guiding the light reflected by the reflection plate to the liquid crystal panel side, and is made of, for example, translucent plastic, and is laminated on the reflection plate 501 a provided on the bottom surface of the lighting device 500. ing. As a material, polycarbonate (PC) resin or cycloolefin-based resin (COP) can be applied.

  The diffusion sheet 503 is for expanding the visual field, and is made of a film having a diffusion transmission function made of, for example, polyethylene terephthalate resin or polyester resin, and is laminated on the light guide plate 502.

  The prism sheet 504 is for improving luminance, and is made of, for example, a sheet obtained by bonding an acrylic resin and a polyester resin, and is laminated on the diffusion sheet 503. Note that a diffusion plate may be further stacked on the prism sheet 504.

  In the case of the present embodiment, a reflective sheet (not shown) is provided on the outer surface of the glass bulb 101 except for a part in the circumferential direction of the lamp 100 (the light guide plate 502 side when inserted into the lighting device 400). An aperture-type lamp may be used.

  As described above, according to the configuration of the illumination device 500 according to the fifth embodiment of the present invention, it is possible to prevent the cold cathode discharge lamp from being damaged by an impact accompanying the movement.

(Sixth embodiment)
FIG. 11A shows a front view of a lighting device according to a sixth embodiment of the present invention, and FIG. 11B shows a cross-sectional view taken along the line AA ′ of FIG. 11A. An illuminating device 600 according to the sixth embodiment of the present invention (hereinafter referred to as “illuminating device 600”) is a luminaire using an annular fluorescent lamp for general illumination.

  The lighting device 600 includes a main body portion 601, a plate-like portion 602, a lamp holder 603, a socket 604, and a lamp 605.

  The main body 601 houses a lighting circuit (not shown) and the like, and an electrical connection part (not shown) is led out from the upper part thereof. For example, the base 606 and the base 606 of the lamp 605 are electrically connected from the side part thereof. A socket 604 for connection is provided.

  The disc-like portion 602 is a member that supports the main body portion 601 and the lamp holder 603, and has, for example, a disc-like shape.

  The lamp holder 603 is attached to the lower surface of the plate-like portion 602. The lamp 605 can be held by, for example, a C-shaped clamping piece provided at the lower end of the lamp holder 602, and the lamp 605 can be prevented from falling.

  The lamp 605 is an annular hot cathode fluorescent lamp, and is substantially the same as the discharge lamp 300 according to the third embodiment except that the shape is annular and the base 606 is located in the middle of the lamp 605. In general.

  As mentioned above, according to the structure of the illuminating device 600 which concerns on the 6th Embodiment of this invention, it can prevent that a cold cathode discharge lamp is damaged by the impact accompanying a movement.

(Seventh embodiment)
FIG. 12 shows an outline of a liquid crystal display device according to the seventh embodiment of the present invention. As shown in FIG. 12, a liquid crystal display device 700 is, for example, a 32 [inch] liquid crystal television, a liquid crystal screen unit 701 including a liquid crystal panel and the like, an illumination device 400 and a lighting circuit 702 according to the fourth embodiment of the present invention. With.

  The liquid crystal screen unit 701 is a known one and includes a liquid crystal panel (color filter substrate, liquid crystal, TFT substrate, etc.) (not shown), a drive module, etc. (not shown), and is based on an image signal from the outside. To form a color image.

  The lighting circuit 702 lights the lamp 100 inside the lighting device 400. The lamp 100 is operated at a lighting frequency of 40 [kHz] to 100 [kHz] and a lamp current of 3.0 [mA] to 25 [mA].

  In addition, in FIG. 12, although the case where the low voltage | pressure discharge lamp 100 which concerns on 1st Embodiment was inserted in the illuminating device 400 which concerns on the 4th Embodiment of this invention as a light source device of the liquid crystal display device 700 was demonstrated, Not limited to this, the discharge lamp 200 according to the second embodiment of the present invention and the discharge lamp 300 according to the third embodiment of the present invention can also be applied. Moreover, also about the illuminating device, the illuminating device 500 which concerns on the 5th Embodiment of this invention can also be used.

  As described above, according to the configuration of the liquid crystal display device according to the seventh embodiment of the present invention, it is possible to prevent the discharge lamp from being damaged by an impact caused by movement.

(Modification)
As described above, the present invention has been described based on the specific examples shown in the above embodiments. However, the content of the present invention is not limited to the specific examples shown in the respective embodiments. Variations can be used.
1. About Glass Bulb (1) About UV Absorption UV light of 254 [nm] and 313 [nm] can be absorbed by doping a glass bulb material, glass, with a transition metal oxide in a predetermined amount. . Specifically, for example, in the case of titanium oxide (TiO ₂ ), the composition ratio of 0.05 [mol%] or more is doped to absorb ultraviolet rays of 254 [nm], and the composition ratio is 2 [mol%] or more. Thus, it is possible to absorb ultraviolet rays of 313 [nm]. However, when titanium oxide is doped more than the composition ratio of 5.0 [mol%], the glass is devitrified, so the composition ratio is 0.05 [mol%] or more and 5.0 [mol%] or less. It is preferable to dope in the range.

In the case of cerium oxide (CeO ₂ ), 254 [nm] ultraviolet rays can be absorbed by doping at a composition ratio of 0.05 [mol%] or more. However, when cerium oxide is doped more than 0.5 [mol%], the glass is colored, so cerium oxide has a composition ratio of 0.05 [mol%] to 0.5 [mol%]. It is preferable to dope in the following range. In addition, since coloring of glass by cerium oxide can be suppressed by doping tin oxide (SnO) in addition to cerium oxide, cerium oxide can be doped to a composition ratio of 5.0 [mol%] or less. . In this case, if cerium oxide is doped with a composition ratio of 0.5 [mol%] or more, ultraviolet rays of 313 [nm] can be absorbed. However, even in this case, when the composition ratio of cerium oxide is more than 5.0 [mol%], the glass is devitrified.

  In the case of zinc oxide (ZnO), ultraviolet rays having a wavelength of 254 [nm] can be absorbed by doping with a composition ratio of 2.0 [mol%] or more. However, when zinc oxide is doped more than 20 [mol%], the glass may be devitrified, so zinc oxide is in the range of 2.0 [mol%] to 20 [mol%]. It is preferable to dope.

Further, in the case of iron oxide (Fe ₂ O ₃ ), 254 [nm] ultraviolet rays can be absorbed by doping at a composition ratio of 0.01 [mol%] or more. However, when iron oxide is doped more than the composition ratio of 2.0 [mol%], the glass is colored, so the iron oxide is contained in the composition ratio of 0.01 [mol%] to 2.0 [mol%]. It is preferable to dope in the following range.
(2) Infrared transmission coefficient The infrared transmission coefficient indicating the water content in the glass is adjusted to be in the range of 0.3 to 1.2, particularly 0.4 to 0.8. Is preferred. When the infrared transmittance coefficient is 1.2 or less, it becomes easy to obtain a low dielectric loss tangent applicable to a high voltage application lamp such as an external electrode discharge lamp (EEFL) or a long cold cathode discharge lamp, and 0.8 or less. If so, the dielectric loss tangent becomes sufficiently small and can be applied to a high voltage application lamp.

  The infrared transmittance coefficient (X) can be expressed by the following formula.

[Expression 1] X = (log (a / b)) / t
a: Transmittance [%] of a minimum point in the vicinity of 3840 [cm ⁻¹ ]
b: Transmittance [%] of a minimum point in the vicinity of 3560 [cm ⁻¹ ].
t: Glass thickness (3) Glass bulb shape The glass bulb shape is not limited to a straight tube shape, and may be, for example, an L shape, a U shape, a U shape, a spiral shape, or the like. . Further, the cross section cut perpendicularly to the tube axis is not limited to a substantially circular shape, and may be, for example, a flat shape such as a track shape or a rounded corner shape, or an elliptical shape.
2. Regarding phosphors in the phosphor layer (1) UV absorption For example, in recent years, with the increase in size of liquid crystal color televisions, polycarbonate with good dimensional stability has been used for the diffusion plate that closes the opening of the backlight unit. ing. This polycarbonate is easily deteriorated by ultraviolet rays having a wavelength of 313 [nm] emitted from mercury. In such a case, a phosphor that absorbs ultraviolet light having a wavelength of 313 [nm] may be used. The following phosphors absorb 313 [nm] ultraviolet rays.

(A) Blue Europium / manganese co-activated barium aluminate / strontium / magnesium [Ba _1-xy Sr _x Eu _y Mg _1-z Mn _z Al ₁₀ O ₁₇ ] or [Ba _1-xy Sr _x Eu _y Mg _{2− z} Mn _z Al ₁₆ O ₂₇ ]
Here, x, y, and z are preferably numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0 ≦ z <0.1, respectively.

Examples of such phosphors include europium activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: BAM-B), Europium activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: SBAM-B) Etc.

(B) Green • Manganese inactive magnesium gallate [MgGa ₂ O ₄ : Mn ²⁺ ] (abbreviation: MGM)
Manganese activated cerium aluminate, magnesium, zinc [Ce (Mg, Zn) Al ₁₁ O ₁₉ : Mn ²⁺ ] (abbreviation: CMZ)
· Active aluminate, cerium-magnesium with terbium ^{_{[CeMgAl 11 O 19: Tb 3+}} ] ( abbreviation: CAT)
• Europium • Manganese co-activated barium aluminate • Strontium • Magnesium [Ba _{1 -xy} Sr _x Eu _y Mg _{1 -z} Mn _z Al ₁₀ O ₁₇ ] or [Ba _{1 -xy} Sr _x Eu _y Mg _{2 -z} Mn _z Al ₁₆ O ₂₇ ]
Here, x, y and z are numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0.1 ≦ z ≦ 0.6, respectively, and z is 0.4 It is preferable that ≦ x ≦ 0.5.

Examples of such phosphors include europium / manganese co-activated barium aluminate / magnesium [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ^{2]. +} ] (Abbreviation: BAM-G), europium / manganese co-activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation: SBAM-G).

(C) Red • Europium activated phosphorus • Yttrium vanadate [Y (P, V) O ₄ : Eu ³⁺ ] (abbreviation: YPV)
Europium activated yttrium vanadate [YVO ₄ : Eu ³⁺ ] (abbreviation: YVO)
・ Europium-activated yttrium oxysulfide [Y ₂ O ₂ S: Eu ³⁺ ] (abbreviation: YOS)
Manganese-activated magnesium fluoride germanate [3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ ] (abbreviation: MFG)
Dysprosium-activated yttrium vanadate [YVO ₄ : Dy ³⁺ ] (red and green two-component phosphor, abbreviation: YDS)
In addition, you may mix and use the fluorescent substance of a different compound with respect to one type of luminescent color. For example, only BAM-B (absorbs 313 [nm]) in blue, LAP (does not absorb 313 [nm]) in green, BAM-G (absorbs 313 [nm]) in green, and YOX in red Alternatively, a phosphor of YVO (absorbs 313 [nm]) may be used. In such a case, as described above, the phosphor that absorbs the wavelength 313 [nm] is adjusted so that the total weight composition ratio is larger than 50%, so that the ultraviolet rays almost leak out of the glass bulb. Can be prevented. Therefore, when the phosphor layer 104 includes a phosphor that absorbs ultraviolet rays of 313 [nm], deterioration due to ultraviolet rays such as a diffusion plate made of polycarbonate (PC) that closes the opening of the backlight unit is suppressed, The characteristics as a backlight unit can be maintained for a long time.

  Here, “absorbing ultraviolet rays of 313 [nm]” means an excitation wavelength spectrum near 254 [nm] (excitation wavelength spectrum means excitation light emission while changing the wavelength of the phosphor, and the excitation wavelength and emission intensity are changed. The intensity of the excitation wavelength spectrum at 313 [nm] is defined as 80 [%] or more. That is, the phosphor that absorbs ultraviolet rays of 313 [nm] is a phosphor that can absorb ultraviolet rays of 313 [nm] and convert it into visible light.

(2) High color reproduction Liquid crystal display devices typified by liquid crystal color televisions have been used as a light source for a backlight unit of the liquid crystal display device in accordance with the recent high color reproduction that has been made as part of higher image quality. There is a need to expand the reproducible chromaticity range in cathode discharge lamps and external electrode discharge lamps.

  In response to such a request, for example, by using the following phosphor, the chromaticity range can be expanded as compared with the case of using the phosphor in the embodiment. Specifically, in the CIE 1931 chromaticity diagram, the chromaticity coordinate value of the phosphor for high color reproduction includes a triangle formed by connecting the chromaticity coordinate values of the three phosphors used in the embodiment. Located at the coordinates that expand the reproduction range.

(A) Blue • Europium-activated strontium chloroapatite [Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SCA), chromaticity coordinates: x = 0.151, y = 0.065
In addition to the above, europium activated strontium, calcium, barium, chloroapatite [(Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SBCA) can also be used, and the wavelength 313 (nm) SBAM-B, which can absorb ultraviolet rays), can also be used for high color reproduction.

(B) Green BAM-G, chromaticity coordinates: x = 0.139, y = 0.574
CMZ, chromaticity coordinates: x = 0.164, y = 0.722
CAT, chromaticity coordinates: x = 0.267, y = 0.663
As described above, these can also absorb ultraviolet rays having a wavelength of 313 [nm], and in addition to the three phosphor particles described here, MGM can also be used for high color reproduction.

(C) Red • YOS, chromaticity coordinates: x = 0.651, y = 0.344
YPV, chromaticity coordinates: x = 0.658, y = 0.333
MFG, chromaticity coordinates: x = 0.711, y = 0.287
As described above, these can also absorb ultraviolet rays having a wavelength of 313 [nm], and besides the three phosphor particles described here, YVO and YDS can also be used for high color reproduction.

  In addition, the chromaticity coordinate values shown above are representative values measured only with each phosphor powder, and due to the measurement method (measurement principle), etc., the chromaticity coordinates indicated by each phosphor powder The value may be slightly different from the value listed above. For reference, the chromaticity coordinate values of the phosphor powders of the first embodiment are YOX (x = 0.644, y = 0.353), LAP (x = 0.351, y = 0.585). , BAM-B (x = 0.148, y = 0,056).

  Furthermore, the phosphor used for emitting each color of red, green, and blue is not limited to one type for each wavelength, and a plurality of types may be used in combination.

  Here, the case where a phosphor layer is formed using the above-described phosphor particles for high color reproduction will be described. In this evaluation, there are three evaluations in the case of using a phosphor for high color reproduction based on the area of NTSC triangle (NTSC triangle) connecting the chromaticity coordinate values of the three primary colors of the NTSC standard in the CIE1931 chromaticity diagram. It is performed by a ratio of the area of a triangle formed by connecting chromaticity coordinate values (hereinafter referred to as NTSC ratio).

  For example, when BAM-B is used as blue, BAM-G as green, and YVO as red (Example 1), the NTSC ratio is 92%, and SCA is used as blue, BAM-G as green, and YVO as red. (Example 2) When NTSC ratio is 100%, SCA is used as blue, BAM-G is used as green, and YOX is used as red (Example 3), NTSC ratio is 95%. The luminance can be improved by 10 [%] as compared with the above.

Note that the chromaticity coordinate values used for the evaluation here are measured in the state of a liquid crystal display device in which a lamp or the like is incorporated, so that the color reproduction range is around the above value depending on the combination with the color filter. there is a possibility.
3. Regarding the types of lamps In the above embodiments, the cold cathode fluorescent lamp has been mainly described as the discharge lamp. However, the present invention is not limited to this, and an external internal electrode fluorescent lamp or the like may be used. Moreover, the ultraviolet lamp in which the fluorescent substance layer is not formed in the inner surface of a glass bulb may be sufficient.

  Moreover, it is not limited to a straight tube lamp, but may be an L shape, a U shape, a U shape, a spiral shape, or the like.

  The present invention can be widely applied to discharge lamps, illumination devices, and liquid crystal display devices.

(A) Sectional drawing including the tube axis | shaft of the low pressure discharge lamp which concerns on the 1st Embodiment of this invention, (b) The principal part expanded sectional view of the A section of Fig.1 (a). The principal part expanded sectional view containing the tube axis | shaft of the low pressure discharge lamp which concerns on the 1st Embodiment of this invention. Conceptual diagram showing the experimental jig of Experiment 2 Conceptual diagram showing the experimental jig of Experiment 3 Conceptual diagram showing the experimental jig of Experiment 4 The front view of the modification of the low voltage | pressure discharge lamp which concerns on the 1st Embodiment of this invention Sectional drawing containing the tube axis | shaft of the low voltage | pressure discharge lamp which concerns on the 2nd Embodiment of this invention. Sectional drawing containing the tube axis | shaft of the low voltage | pressure discharge lamp which concerns on the 3rd Embodiment of this invention. The disassembled perspective view of the illuminating device which concerns on the 4th Embodiment of this invention. Partially cutaway perspective view of a lighting apparatus according to a fifth embodiment of the present invention (A) Front view of lighting apparatus according to sixth embodiment of the present invention, (b) AA ′ cross-sectional view of FIG. The perspective view of the liquid crystal display device which concerns on the 7th Embodiment of this invention Expanded sectional view of the main part including the tube axis of a conventional discharge lamp

Explanation of symbols

100, 200, 300 Low pressure discharge lamp 101, 301 Glass bulb 102 Electrode 103 Lead wire 105 Oxide film 201 External electrode 400, 500, 600 Illumination device 700 Liquid crystal display device

Claims (7)

A glass bulb having a thermal expansion coefficient of 8.0 × 10 ⁻⁶ [K ⁻¹ ] or more and 10.0 × 10 ⁻⁶ [K ⁻¹ ] or less, an electrode disposed inside the glass bulb, A low-pressure discharge lamp having a lead wire connected to the electrode and sealed to at least one end of the glass bulb,
An oxide film is formed on the surface of the sealing portion in the lead wire,
The low-pressure discharge lamp is characterized in that the thickness of the oxide film has a distribution such that both end portions are thicker than the center portion in the direction of the axis of the lead wire. 2. The low-pressure discharge lamp according to claim 1, wherein the thickness of the oxide film has a distribution that increases in thickness in a direction from the center to both ends in the direction of the axis of the lead wire. 3. The low-pressure discharge lamp according to claim 1, wherein the oxide film has a maximum thickness of 1.0 [μm] to 3.0 [μm] at both ends. . The low-pressure discharge lamp according to any one of claims 1 to 3, wherein the lead wire is formed of an alloy of iron and nickel, and the oxide film is formed of iron oxide. The electrode has a bottomed cylindrical shape,
The difference between the inner diameter of the glass bulb and the outer diameter of the electrode is within 4 [mm],
5. The low-pressure discharge lamp according to claim 1, wherein a length of the lead wire in the electrode in a direction of a line axis is in a range of 7 [mm] or more and 20 [mm] or less. An illuminating device comprising the low-pressure discharge lamp according to claim 1. A liquid crystal display device comprising the illumination device according to claim 6.

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