JP2008251430A - Glass tube for lamp, low-voltage discharge lamp, backlight unit, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass tube for a lamp capable of preventing generation of cracks in glass, even in case soft glass such as soda glass or lead-free glass is used as a glass material, as well as a low-voltage discharge lamp, a backlight unit, and a liquid crystal display. <P>SOLUTION: The glass tube for a lamp has a thermal expansion coefficient of 60 [K<SP>-1</SP>] to 110 [K<SP>-1</SP>], at least its outer surface layer being an ion exchange layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a glass tube for a lamp, a low-pressure discharge lamp, a backlight unit, and a liquid crystal display device.

FIG. 16 is a cross-sectional view including a tube axis X ₁ of a conventional low-pressure discharge lamp, for example, a cold cathode fluorescent lamp 1. The conventional cold cathode fluorescent lamp 1 is frequently used as a light source (backlight) of a liquid crystal display device such as a liquid crystal television. This type of cold cathode fluorescent lamp 1 includes a glass bulb 2 and electrodes 3 provided at both ends of the glass bulb 2, and has an inner diameter of, for example, 1 [ mm] to 6 [mm] and has a long shape of, for example, 300 [mm] to 1500 [mm]. Recently, liquid crystal televisions have been increased in size, and thus a longer-length cold cathode fluorescent lamp 1 has been demanded.

Since the cold cathode fluorescent lamp 1 has such a small diameter and a long shape, a glass bulb 2 made of hard glass such as borosilicate glass is used among many types because of problems such as glass workability. Used (see, for example, Patent Document 1).
JP 2005-56707 A

  However, as the glass bulb 2 of the cold cathode fluorescent lamp 1, many applicability of soft glass such as soda glass and lead-free glass used in fluorescent lamps for general illumination have been proposed. Application to such soft glass may be advantageous in terms of cost, for example.

  However, at present, these soft glasses are actually applied and not put into practical use at all. One of the reasons is that these soft glasses have lower mechanical strength than the hard glass. That is, as described above, the cold cathode fluorescent lamp 1 has a small diameter and is long, so that cracks are likely to occur in the glass bulb 2 during the manufacturing process and transportation process of the lamp.

  Therefore, the present invention breaks the situation that has remained at such a proposal level, and even when a soft glass such as soda glass or lead-free glass is used as a glass material, the occurrence of cracks in the glass is prevented. An object of the present invention is to provide a glass tube for a lamp, a low-pressure discharge lamp, a backlight unit, and a liquid crystal display device.

In order to solve the above problems, the glass tube for a lamp according to the present invention has a thermal expansion coefficient of 60 [K ⁻¹ ] to 110 [K ⁻¹ ], and at least its outer surface layer is an ion exchange layer. It is characterized by that.

  Further, in the glass tube for a lamp according to the present invention, the concentration of the alkali metal having a larger ion radius than sodium in the ion exchange layer is higher than the concentration of the alkali metal having a larger ion radius than sodium in the non-ion exchange layer. Is preferred.

  In the glass tube for a lamp according to the present invention, the alkali metal is preferably potassium.

  In the glass tube for a lamp according to the present invention, the thickness of the ion exchange layer may be 5 [μm] or more.

  In the glass tube for a lamp according to the present invention, the ion exchange layer includes two layers, a first ion exchange layer and a second ion exchange layer located outside the first ion exchange layer, and the first ion exchange layer. The concentration of the alkali metal having a larger ion radius than sodium in the exchange layer is higher than the concentration of the alkali metal having a larger ion radius than sodium in the non-ion exchange layer, and the concentration of the alkali metal in the second ion exchange layer is It is preferable that the concentration is lower than the alkali metal concentration of one ion exchange layer.

  In the lamp glass tube according to the present invention, the boron oxide content is preferably in the range of 0 [mol%] to 5 [mol%].

  In the lamp glass tube according to the present invention, the alumina content is preferably in the range of 0 [mol%] to 5 [mol%].

  In the glass tube for a lamp according to the present invention, the total content of the alkali metal oxide and the alkaline earth metal oxide is in the range of 10 [mol%] to 30 [mol%] and is oxidized. The total content of strontium and barium oxide is preferably in the range of 0 [mol%] to 12 [mol%].

  The glass tube for a lamp according to the present invention has an inner diameter of 1 [mm] to 8 [mm], a thickness of 0.2 [mm] to 0.6 [mm], and a length of 300 [mm] or more. It is preferable that it is 2000 [mm] or less.

  The method for producing a glass tube for a lamp according to the present invention includes a first ion exchange layer forming step including a step of immersing at least a glass tube in a molten salt of an alkali metal having an ionic radius larger than sodium, and at least the first ion exchange. Including a second ion exchange layer forming step including a step of immersing the glass tube that has undergone the layer forming step in a molten salt of an alkali metal having an ion radius smaller than that of the alkali metal used in the first ion exchange layer forming step. And

  The low-pressure discharge lamp according to the present invention includes the glass tube for a lamp.

  The backlight unit according to the present invention includes the low-pressure discharge lamp.

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

  The glass tube for a lamp, the low-pressure discharge lamp, the backlight unit and the liquid crystal display device according to the present invention are free from cracks even when soft glass such as soda glass or lead-free glass is used as the glass material. Can be prevented.

(First embodiment)
In FIGS. 1 (a) a sectional view including the tube axis X ₁₀₀ of the glass tube lamp according to a first embodiment of the present invention, respectively the enlarged sectional view of the A portion in FIG. 1 (b). The lamp glass tube 100 according to the first embodiment of the present invention (hereinafter simply referred to as “glass tube 100”) has a thermal expansion coefficient of 60 [K ⁻¹ ] to 110 [K ⁻¹ ], for example, 92.5. [K ⁻¹ ], a part of the outer surface layer is formed from an ion exchange layer 100a formed by an ion exchange treatment described later, and a non-ion exchange layer 100b having an original glass composition that is not ion-exchanged. Is done.

<Description of ion exchange layer>
In the ion exchange layer 100a, the concentration of the alkali metal having a larger ion radius than that of sodium is higher than the concentration of the alkali metal having a larger ion radius than that of sodium in the non-ion exchange layer 100b. Hereinafter, the process of forming the ion exchange layer 100a will be described with reference to FIG. 2 in the case of using potassium as an example of an alkali metal having an ionic radius larger than that of sodium.

<Immersion process>
First, as shown in FIG. 2A, a glass tube before the ion exchange treatment (hereinafter simply referred to as “glass tube 101”) is prepared. The glass tube 101 has, for example, the composition shown in Table 1, and has a total length of 730 [mm], an outer diameter of 4 [mm], an inner diameter of 3 [mm], and a wall thickness of 0.5 [mm].

The glass tube 101 is immersed in a bath 103 containing potassium nitrate (KNO ₃ ) molten salt 102 heated to 350 [° C.] to 450 [° C.], for example, 10 [min] to 120 [min]. The thickness of the ion exchange layer 100a can be changed by the time during which the glass tube 101 is immersed in the potassium nitrate molten salt 102. When it is desired to form the ion exchange layer 100a only on the outer surface layer of the glass tube 101, it is preferable to plug soda glass, quartz or the like at both ends of the glass tube 101.

<Washing process>
Next, as shown in FIG. 2 (b), the glass tube 100 after the ion exchange treatment is washed with a bath 105 containing water 104, thereby removing excess potassium nitrate molten salt 102 adhering to the surface of the glass tube 100. To do.

<Drying process>
Next, as shown in FIG.2 (c), the glass tube 100 is dried with the heater 106 etc., and the water | moisture content adhering at the washing | cleaning process is removed.

  The glass tube 100 is completed through the above steps.

<Image of ion exchange layer formation>
Then, the image figure of the principal part expanded cross section of the outer surface layer of the glass tube 101 of the immersion process initial stage is shown to Fig.3 (a), The image figure of the principal part expanded cross section of the outer surface layer of the glass tube 100 of the immersion process last stage is FIG. Each is shown in (b). As shown in FIG. 3A, in the initial stage of the dipping process, sodium ions (Na ⁺ ) are distributed on the outer surface layer of the glass tube 101, as in the other portions of the glass tube 101. . On the other hand, as shown in FIG. 3B, at the end of the dipping process, some of the sodium ions in the outer surface layer of the glass tube 100 are exchanged with potassium ions (K ⁺ ) contained in the potassium nitrate molten salt. More potassium ions are distributed in the outer surface layer of the glass tube 100 than in other portions of the glass tube 100. The ion radius of this potassium ion is larger than the ion radius of a sodium ion. Accordingly, in such an ion exchange layer 100a, compressive stress is applied because potassium ions having a larger ion radius than the sodium ions are accommodated in a portion where sodium ions having a small ion radius are accommodated. By forming the ion exchange layer 100a on which the compressive stress works in this way on the outer surface layer of the glass tube 100, the glass tube 100 becomes strong against external impact, and the mechanical strength of the glass tube 100 is increased. It can improve and can prevent a crack from generating.

<Description of non-ion exchange layer>
Table 1 shows specific composition ratios of the non-ion exchange layer 100b.

  In addition, the composition ratio described in Table 1 is an oxide conversion. Hereinafter, in the present embodiment and other embodiments, the values converted into oxides are used for all the descriptions of the composition ratio and the content ratio. Moreover, since the ion exchange layer 100a is only formed on the outer surface layer of the glass tube 100, the composition ratio of the glass tube 100 and the non-ion exchange layer 100b is substantially the same.

However, the composition of the non-ion exchange layer 100b is not limited to the one shown in Table 1, and any thermal expansion coefficient may be 60 [K ⁻¹ ] or more and 110 [K ⁻¹ ] or less.

  However, the content of sodium oxide in the non-ion exchange layer 100b is preferably in the range of 5 [mol%] to 15 [mol%]. In this case, since the ion exchanged sodium is sufficiently contained in the glass tube 100, the ion exchange layer 100a can be easily formed.

The content of boron oxide of the non-ion exchange layer 100b (B ₂ O ₃₎ is preferably in the range of 0 [mol%] or more 5 [mol%]. In this case, by suppressing the amount of boron that suppresses the precipitation of sodium, the behavior of sodium ions in the glass tube 100 can be activated, and the ion exchange layer 100a can be easily formed. . In particular, the content of boron oxide (B ₂ O ₃ ) in the non-ion exchange layer 100b is more preferably in the range of 0 [mol%] to 3 [mol%]. In this case, the behavior of sodium ions in the glass tube 100 can be further activated by further suppressing the amount of boron that suppresses the precipitation of sodium, and the ion exchange layer 100a can be easily formed. Can do.

The content of alumina (Al ₂ O ₃ ) in the non-ion exchange layer 100b is preferably in the range of 0 [mol%] to 5 [mol%]. In this case, by suppressing the amount of aluminum that suppresses precipitation of sodium, the behavior of sodium ions in the glass tube 100 can be activated, and the ion exchange layer 100a can be easily formed. . In particular, the content of alumina (Al ₂ O ₃ ) in the non-ion exchange layer 100b is more preferably in the range of 1.5 [mol%] to 5 [mol%]. In this case, the number of aluminum ions in the glass tube 100 is six-coordinate than that of the four-coordinate. Since the strength of each bond is weaker in the 6-coordinate than in the 4-coordinate, the aluminum ion also affects the binding of other components in the glass tube 100, such as sodium ions. Sodium ions can be easily eluted and the ion exchange layer 100a can be easily formed.

The content of boron oxide (B ₂ O ₃ ) in the non-ion exchange layer 100b is in the range of 0 [mol%] to 5 [mol%], and the content of alumina (Al ₂ O ₃ ). Is preferably in the range of 1.5 [mol%] to 4 [mol%]. In this case, a part of boron in the glass tube 100 is converted from a covalent bond to an ionic bond, and the bond strength of each bond is weakened. Therefore, other components other than boron in the glass tube 100, such as sodium ions This also affects the binding of sodium ions, so that sodium ions can be easily eluted and the ion exchange layer 100a can be easily formed.

  The total content of the alkali metal oxide and the alkaline earth metal oxide in the non-ion exchange layer 100b is in the range of 10 [mol%] to 30 [mol%], and strontium oxide ( The total content of SrO) and barium oxide (BaO) is preferably in the range of 0 [mol%] to 12 [mol%]. In this case, since strontium ions and barium ions have a larger ionic radius than sodium ions, the sodium ions are prevented from moving from the glass to the outside, and the formation of the ion exchange layer 100a is prevented from being hindered. Can do.

<Experiment>
The inventors conducted a destructive test on the glass tubes A ₁ , A ₂ , A ₃ subjected to the ion exchange treatment and the untreated glass tube B, and investigated the breaking strength of both.

The glass materials used in the experiments are all lead-free glass shown in Table 1 as glass a in Table 1. The overall length is 150 [mm], the outer diameter is 4.0 [mm], and the inner diameter is 3.0 [mm]. ]. In performing the ion exchange treatment, the ion exchange treatment was performed by dipping in a molten potassium nitrate salt at a heating temperature of about 540 [° C.]. However, the glass tubes A ₁ , A ₂ , and A ₃ differ only in the immersion time as described below.

(1) Glass tube A ₁ : immersion time 120 [min]
(2) Glass tube A ₂ : immersion time 180 [min]
(3) Glass tube A ₃ : immersion time 240 [min]
In the destructive test, a universal testing machine is used. As shown in FIG. 4, a concentrated load is applied to the center of the glass tube supported by the support member 107 with a span of 70 [mm] by the indenter 108, and the bending load is applied to the glass tube. Was performed by a three-point bending method. The load value [kgf] when the glass tube broke (when it broke) was recorded as the breaking strength. The moving speed of the indenter for applying the concentrated load was 1 [mm / min].

Each of the four types of glass tubes A ₁ , A ₂ , A ₃ , and B was prepared for 12 [pieces] and tested. The test results are shown in Table 2. Table 2 shows the 50% fracture strength and the Weibull coefficient in the Weibull determination for various glass tubes A ₁ , A ₂ , A ₃ , and B. It shows that the larger the value of 50 [%] fracture strength, the stronger the mechanical strength of the glass tube, and the greater the Weibull coefficient, the smaller the variation in mechanical strength.

As shown in Table 2, it can be seen that the glass tube A ₁ , the glass tube A ₂ and the glass tube A ₃ are all improved in mechanical strength compared to the glass tube B which has not been subjected to ion exchange.

Here, elemental analysis of the outer surface layer of each glass tube A ₁ , A ₂ , A ₃ , B is performed by JMX-8900 manufactured by JEOL Ltd., and glass tubes A ₁ , A ₂ , A ₃ , B The concentration of sodium and potassium in the outer surface layer was investigated.

First, FIG. 6 shows an elemental analysis measurement method for glass tubes A ₁ , A ₂ , A ₃ , and B. The glass tubes A ₁ , A ₂ , A ₃ , and B are cut perpendicularly to the tube axis at the center in the tube axis direction to produce a measurement sample 109 having a thickness s of 10 [mm] in the tube axis direction. . The measurement points were arbitrary 4 [locations] (outer surface layer ₁ to outer surface layer ₄ ) at equal intervals among the outer surface layers on the cut surface, and were surrounded by a square of 100 [μm] on one side. Part. The measurement result was calculated by an average value of the values at 4 [locations].

The measurement results are shown in FIGS. 5 (a1) to (a4) and (b1) to (b4). FIGS. 5A1 to 5A4 show changes in sodium concentration, and FIGS. 5B1 to 5B4 show changes in potassium concentration. Figure 5 (a1) and the (b1) is a glass tube B of the ion exchange untreated, Figure 5 (a2) and (b2) is a glass tube A ₁ subjected to ion exchange treatment with immersion time 120 [min], FIG. 5 (a3) and (b3) show a glass tube A ₂ subjected to an ion exchange treatment at an immersion time of 180 [min], and FIGS. 5 (a4) and (b4) show an ion exchange treatment at an immersion time of 240 [min]. Glass tubes A ₃ are shown respectively.

  5 (a1) to (a4) and (b1) to (b4), the horizontal axis represents the depth [μm] from the outermost surface, and the change in the concentration of sodium is represented by color shading. . However, in the drawing, the color shading boundary is clear and linear, but this is a schematic and the actual density change is continuous and the boundary may not be clearly recognized. Absent.

As apparent from FIGS. 5 (a1) to (a4), in the glass tubes A ₁ , A ₂ , and A ₃ subjected to the ion exchange treatment, the concentration of sodium in the outer surface layer is that of the glass tube B that has not been subjected to the ion exchange treatment. The lower the sodium concentration and the closer to the outermost surface, and the longer the immersion time, the deeper the region of lower concentration than the sodium concentration of the glass tube B. On the contrary, as apparent from FIGS. 5 (a1) to (a4), in the glass tubes A ₁ , A ₂ and A ₃ , the potassium concentration in the outer surface layer exceeds the potassium concentration in the glass tube B. The closer to the outermost surface, the higher the immersion time, and the deeper the region of higher concentration than the potassium concentration of the glass tube B.

  Here, when the ion exchange layer 100a is defined as a region in which the potassium content is 1% or more higher than the potassium content in the non-ion exchange layer 100b, the thickness of the ion exchange layer 100a is 5%. [Μm] or more is preferable. In the process, the thickness of the ion exchange layer may vary, and in order to sufficiently improve the mechanical strength of the entire glass tube 100 even if the variation is taken into account, the thickness should be 5 [μm] or more. Is preferable. Furthermore, the thickness of the ion exchange layer 100a is more preferably 30 [μm] or more. This is because the mechanical strength of the glass tube 100 is further improved, the outer surface of the glass tube 100 is hardly damaged, and the glass tube 100 is less likely to be damaged by an external load.

  When the ion exchange layer 100a is defined as a region where the potassium content is 2% or more higher than the potassium content in the non-ion exchange layer 100b, the ion exchange is performed for the same reason as described above. The thickness of the layer 100a is preferably 2 [μm] or more, and more preferably 20 [μm] or more.

In addition, although the content rate of potassium in the non-ion exchange layer 100b is the content rate of potassium of the part in which the ion exchange process is not performed in the glass tube 100, it is preferable to measure with the following measuring methods. That is, any 4 [locations] (central portion ₁ to central portion ₄ ) that are equally spaced in the central portion in the thickness direction on the cut surface of the measurement sample 109 shown in FIG. Measure the part surrounded by. And a measurement result is computed by the average value of the value in the 4 [locations]. Since the ion exchange layer 100a is sequentially formed from the surface of the glass tube 100, when the ion exchange treatment is performed on both the inner surface layer and the outer surface layer of the glass tube 100, the central portion in the thickness direction of the glass tube 100 is the most. This is because ion exchange is difficult. However, when only the outer surface layer of the glass tube 100 is subjected to ion exchange treatment, the inner surface side of the glass tube 100 is most difficult to exchange ions, so that the center of the measurement point is 100 [μm] inside from the inner surface of the glass tube 100. And it is preferable to measure arbitrary 4 [locations] that are equally spaced. Here, the center of the measurement point is set to be 100 [μm] from the inner surface of the glass tube 100, because the inner surface of the glass tube 100 is exposed to the outside air, and the measured value may become unstable. Because.

  In this experiment, the glass tube 100 shown in Table 1 was used as the composition of the glass tube 100. However, the present invention is not limited to this. For example, the same results were obtained with the glass b and c compositions shown in Table 1. .

<Summary>
As described above, according to the configuration of the glass tube for lamp 100 according to the first embodiment of the present invention, even when soft glass such as soda glass or lead-free glass is used as the material, cracks are generated in the glass. Can be prevented.

  By the way, the liquid crystal display device tends to be thin and large, and there is a similar tendency with respect to the backlight unit and the backlight mounted therein. In order to achieve this, glass tubes used for backlights such as cold cathode fluorescent lamps, external electrode fluorescent lamps, hot cathode fluorescent lamps, and the like are required to be thin and long. Specifically, the inner diameter is 1 [mm] or more and 8 [mm] or less, the thickness is 0.2 [mm] or more and 0.6 [mm] or less, and the length is 300 [mm] or more and 2000 [mm] or less. . However, as the length of the thin tube is increased, the load applied to the glass tube 100 is increased, and the mechanical strength of the glass tube 100 is further required. The glass tube for a lamp according to the first embodiment of the present invention is most effective for a long glass tube made of such a thin tube, and is used for a load when the glass tube is transferred, or a backlight unit. It is possible to prevent damage due to a load at the time of insertion or a load at the time of transfer after being inserted into the backlight unit.

  Moreover, when the ion exchange layer is formed not only on the outer surface layer of the glass tube 100 but also on the inner surface layer, the mechanical strength of the glass tube 100 can be further improved.

  In the present embodiment, potassium has been described in detail as an alkali metal having an ionic radius larger than that of sodium. However, other alkali metals such as rubidium (Rb) and cesium (Cs) can be applied. .

(Second Embodiment)
FIG. 7A shows a cross-sectional view including the tube axis X ₂₀₀ of the low-pressure discharge lamp according to the second embodiment of the present invention, and FIG. 7B shows an enlarged cross-sectional view of a main part B thereof. A low-pressure discharge lamp 200 (hereinafter simply referred to as “lamp 200”) according to the second embodiment of the present invention is a cold cathode fluorescent lamp, and is provided at a glass bulb 201 and at both ends of the glass bulb 201. The internal electrode 3 and a lead wire 202 having one end connected to the internal electrode 3 and the other end led out from the tube end of the glass bulb 201.

<Description of glass bulb>
The glass bulb 201 is obtained by processing the glass tube 100 for a lamp according to the first embodiment of the present invention. The glass bulb 201 has a ring-shaped cross section cut perpendicular to the tube axis X ₂₀₀ and has a total length of 730 [ mm], the outer diameter is 4 [mm], the inner diameter is 3 [mm], and the wall thickness is 0.5 [mm]. For example, both ends of the glass bulb 201 are sealed with glass beads 203. The glass bulb 201 can be sealed using various known methods such as a pinch seal method.

A phosphor layer 204 is formed on the inner surface of the glass bulb 201. The phosphor layer 204 includes, for example, a red phosphor (Y ₂ O ₃ : Eu ²⁺ ), a green phosphor (LaPO ₄ : Ce ³⁺ , Tb ³⁺ ), and a blue phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu ^{2). +} ) And a rare earth phosphor.

  The distance between the outer end of the glass bulb 201 and the end of the phosphor layer 204 closer to this end, that is, the length of the region of the glass bulb 201 where the phosphor layer 204 is not formed is the both sides of the glass bulb 201. It is preferable that they are different. When the glass bulb 201 is long and thin, it is difficult to form the phosphor layer 204 having a uniform film thickness on the inner surface of the glass bulb 201. That is, the thickness of the phosphor layer 204 is not uniform in the longitudinal direction of the glass bulb 201, and increases, for example, from one end side to the other end side. When such a plurality of lamps 200 are arranged in a plurality of backlight units (not shown) and assembled in an arbitrary direction, there is a possibility that luminance unevenness occurs as a whole backlight unit. In order to prevent this, it is necessary to alternately reverse the direction of the tube axis direction of the lamp 200 incorporated in the backlight unit one by one. Alternatively, even when only one lamp 200 is used, it is necessary to correct the optical system according to the direction of the lamp 200. That is, in any case, in order to automatically insert the lamp 200 into the socket (not shown), it is necessary to be able to automatically determine the direction of the lamp 200. Therefore, as a method for automatically determining the direction of the lamp 200, for example, a sensor identifies the distance between the outer end of the glass bulb 201 at both ends of the lamp 200 and the end of the phosphor layer 204 closer to this end. A way to do this is possible The difference in distance is preferably 2 [mm] or more. This is because the length is sufficiently discriminable by the sensor and almost no discrimination error occurs.

In addition, between the inner surface of the glass bulb 201 and the phosphor layer 204, for example, yttrium oxide (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ), calcium oxide (CaO), silica (SiO ₂ ), etc. A protective film made of a metal oxide may be formed.

  Inside the glass bulb 201, for example, about 2 [mg] mercury and a mixed gas of Neon and argon (Ne95 [%] + Ar5 [%] of about 8 [kPa] (20 [° C.]) as a rare gas. ]) Are enclosed. The partial pressure ratio of the mixed rare gas is not limited to this, and neon may be set in the range of 60 [%] to 99.9 [%] and the remainder may be occupied by argon. The gas pressure may also be changed within the range of 6 [kPa] to 18 [kPa].

<Description of internal electrode>
The internal electrode 3 is a bottomed cylindrical hollow electrode made of nickel (Ni), for example, and has a total length of 5.2 [mm], an outer diameter of 2.7 [mm], and an inner diameter of 2.3 [mm]. The wall thickness is 0.2 [mm]. The material of the internal electrode 3 is not limited to nickel, and may be, for example, niobium (Nb), tantalum (Ta), molybdenum (Mo), or tungsten (W). The internal electrode 3 is disposed so that the tube axis thereof and the tube axis of the glass bulb 201 are substantially coincident with each other, and the distance between the outer surface and the inner surface of the glass bulb 201 is substantially uniform over the entire region. .

  The distance between the outer surface of the internal electrode 3 and the inner surface of the glass bulb 201 is preferably 0.2 [mm] or less, for example, set to 0.15 [mm]. In this way, by setting the interval to 0.2 [mm] or less, during lighting, discharge does not enter the space formed between the outer surface of the internal electrode 3 and the inner surface of the glass bulb 201, and the internal electrode 3 Discharge occurs only inside. Therefore, it becomes difficult for the discharge during lighting to shift to the outside of the internal electrode 3, the excessive sputtering on the inner surface of the glass bulb 201 can be suppressed, the mercury consumption rate can be suppressed, and the life of the lamp 200 can be extended. Can be planned. Further, by preventing the discharge from wrapping around the lead wire 202, the consumption of the lead wire 202 can be suppressed.

<Description of lead wire>
The lead wire 202 is, for example, a joint between an internal lead wire 202a made of Jumet and an external lead wire 202b made of nickel (Ni) that easily adheres to solder or the like, and is joined to the internal lead wire 202a and the external lead wire 202b. The surface is substantially flush with the outer surface of the glass bulb 201. That is, one end of the internal lead wire 202a is electrically and mechanically connected to the bottom of the hollow internal electrode 3, and most of the other end side connected to the external lead wire 202b is the glass bead 203. Is sealed. The external lead wire 202 b is substantially entirely located outside the glass bulb 201. The internal lead wire 202a has, for example, a total length of 3 [mm] and a wire diameter of 1.0 [mm]. The external lead wire 202b has, for example, a total length of 10 [mm] and a linear shape of 0.8 [mm].

  Note that the configuration of the lead wire 202 is not limited to the above-described configuration. For example, the internal lead wire 202a and the external lead wire 202b are not separated, and are configured by a single wire made of an alloy of iron and nickel, for example. Alternatively, the internal lead wire 202a or the external lead wire 202b may be further connected to a plurality of wires.

<Summary>
As described above, according to the configuration of the low-pressure discharge lamp 200 according to the second embodiment of the present invention, even when soft glass such as soda glass or lead-free glass is used as the material of the glass bulb 201, Generation of cracks can be prevented.

(Third embodiment)
FIG. 8A shows a cross-sectional view including the tube axis X ₃₀₀ of the glass tube for a lamp according to the third embodiment of the present invention, and FIG. The glass tube for lamp 300 according to the third embodiment of the present invention (hereinafter simply referred to as “glass tube 300”) has a thermal expansion coefficient of 60 [K ⁻¹ ] to 110 [K ⁻¹ ], for example, 92.5. [K ⁻¹ ], a part of the outer surface layer is formed from an ion exchange layer 300a formed by an ion exchange treatment described later, and a non-ion exchange layer 100b having an original glass composition that is not ion-exchanged. Is done. Since the glass tube 300 has substantially the same configuration as the glass tube for a lamp according to the first embodiment of the present invention except for the ion exchange layer 300a, the ion exchange layer 300a will be described in detail. Other points are omitted.

<Description of ion exchange layer>
The ion exchange layer 300a is composed of two layers, a first ion exchange layer 300b and a second ion exchange layer 300c located outside the first ion exchange layer 300b, and has a larger ion radius than sodium in the first ion exchange layer 300b. The concentration of alkali metal is higher than the concentration of alkali metal having an ionic radius larger than that of sodium in non-ion exchange layer 100b, and the concentration of alkali metal in second ion exchange layer 300c is the concentration of alkali metal in first ion exchange layer 300b. Is lower than. Hereinafter, the process of forming the ion exchange layer 300a will be described with reference to FIG. 9 in the case where potassium is used as an alkali metal having an ionic radius larger than that of sodium.

<First immersion process>
First, as shown to Fig.9 (a), the glass tube 101 before an ion exchange process is prepared. The glass tube 101 has the composition shown in Table 1 which is substantially the same as that used in the lamp glass tube 100 according to the first embodiment of the present invention, and has a total length of 730 [mm] and an outer diameter. Is 4 [mm], the inner diameter is 3 [mm], and the wall thickness is 0.5 [mm]. This glass tube 101 is immersed, for example, in a range of 60 [min] to 240 [min] in a bath 302 containing potassium nitrate (KNO ₃ ) molten salt 301 heated to 350 [° C.] to 450 [° C.]. The film thickness of the first ion exchange layer 300b can be changed according to the time during which the glass tube 101 is immersed in the potassium nitrate molten salt 301.

<First cleaning step>
Next, as shown in FIG. 9 (b), the excess potassium nitrate molten salt 301 adhering to the surface of the glass tube 303 is obtained by washing the glass tube 303 after the first immersion step in a bath 305 containing water 304. Remove.

<First drying step>
Next, as shown in FIG. 9C, the glass tube 303 is dried with a heater 306 or the like, thereby removing moisture adhering in the cleaning process.

<Second immersion process>
Next, as shown in FIG. 9D, the glass tube 303 is placed in a bath 308 containing a sodium nitrate (NaNO ₃ ) molten salt 307 heated to 350 [° C.] to 450 [° C.], for example, 60 [min]. Immerse for ~ 240 [min]. The film thickness of the second ion exchange layer 300c can be changed according to the time during which the glass tube 303 is immersed in the sodium nitrate molten salt 307.

<Second cleaning step>
Next, as shown in FIG. 9 (e), the excess sodium nitrate molten salt 307 adhering to the surface of the glass tube 300 is washed by washing the glass tube 300 after the second immersion step in a bath 310 containing water 309. Remove.

<Second drying step>
Next, as shown in FIG. 9 (f), the glass tube 300 is dried by a heater 311 or the like, thereby removing water adhering in the cleaning process.

  The glass tube 300 is completed through the above steps.

<Image of ion exchange layer formation>
Next, a process in which the ion exchange layer 300a is formed on the outer surface layer of the glass tube 300 will be described. FIG. 10A is an image view of an enlarged cross section of the main part of the outer surface layer of the glass tube 101 in the initial stage of the first immersion process, and FIG. 10A is an image diagram of an enlarged cross section of the main part of the outer surface layer of the glass tube 303 at the end of the first immersion process. FIG. 10 (c) shows an image view of an enlarged cross-section of the main part of the outer surface layer of the glass tube 300 at the end of the second immersion process. As shown in FIG. 10A, sodium ions (Na ⁺ ) are distributed on the outer surface layer of the glass tube 101 in the same manner as other portions of the glass tube 101. On the other hand, as shown in FIG. 10B, at the end of the first immersion step, a part of sodium ions is ion-exchanged with potassium ions (K ⁺ ) contained in the potassium nitrate molten salt. On the outer surface layer of 303, a first ion exchange layer 300b in which more potassium ions are distributed than in other portions of the glass tube 303 is formed. The ionic radius of potassium ions is larger than the ionic radius of sodium ions. Therefore, in such a first ion exchange layer 300b, compressive stress is applied by accommodating potassium ions having a larger ion radius than the sodium ions in a portion where sodium ions having a smaller ion radius are accommodated. By forming the first ion exchange layer 300b on which the compressive stress works in this way on the outer surface layer of the glass tube 303, the glass tube 303 becomes strong against external impact, and the mechanical action of the glass tube 303 is increased. Strength can be improved. Next, as shown in FIG. 10C, at the end of the second immersion step, potassium ions in the outer surface layer of the first ion exchange layer 300b are replaced with sodium ions, and the second ion exchange layer 300c is formed. The As a result, the compressive stress acting on the second ion exchange layer 300c is smaller than that of the first ion exchange layer 300b, and the second ion exchange layer 300c has a structure in which scratches or the like are likely to enter. Thus, the ion exchange layer 300a is composed of the first ion exchange layer 300b in which a large compressive stress is applied and the second ion exchange layer 300c in which a small compressive stress is applied on the outer side thereof, so that it is used for a lamp. Even if the outer surface of the glass tube 300 is finely scratched, cracks due to the scratch can be prevented.

  Here, the first ion exchange layer 300b is defined as a region in which the potassium content is 1% or more higher than the potassium content in the non-ion exchange layer 100b, and the second ion exchange layer 300c is defined as When it is defined that the potassium content is lower than the potassium content of the first ion exchange layer 300b outside the first ion exchange layer, the first ion exchange layer 300b is a sufficient machine of the glass tube 300. In order to obtain the desired strength, it is preferably 10 [μm] or more. Furthermore, the first ion exchange layer 300b is more preferably 20 [μm] or more. In this case, the mechanical strength of the glass tube 300 is further improved, and the glass tube 300 is hardly damaged by an external load.

  The second ion exchange layer 300c is more preferably 10 [μm] or more. In this case, even if the surface of the glass tube 300 is scratched, it is difficult for the scratch to reach the inside of the second ion exchange layer 300c. Furthermore, the second ion exchange layer 300c is more preferably 20 [μm] or more. In this case, even if the surface of the glass tube is flawed, the flaw becomes more difficult to reach the inside than the second ion exchange layer 300c, and it is possible to prevent cracks due to the flaw. It is.

  The total thickness of the first ion exchange layer 300b and the second ion exchange layer 300c is preferably 20 [μm] or more. When the total thickness of the first ion exchange layer 300b and the second ion exchange layer 300c is less than 20 [μm], the second ion exchange layer 300c is formed outside the first ion exchange layer 300b after the first ion exchange layer 300b is formed. This is because it is difficult.

  Moreover, it is preferable that the thickness of the 1st ion exchange layer 300b is thicker than the thickness of the 2nd ion exchange layer 300c. In this case, the mechanical strength of the glass tube 300 can be improved, and even if the outer surface of the glass tube 300 is slightly scratched, it is possible to prevent cracks due to the scratch.

  Furthermore, the thickness of the first ion exchange layer 300b is preferably 5 [μm] or more thicker than the thickness of the second ion exchange layer 300c. In this case, even if the outer surface of the glass tube 300 has more scratches, the progress of the scratches can be suppressed by the first ion exchange layer 100b, so that cracks are caused due to the scratches. This is because it can be prevented.

<Summary>
As described above, according to the configuration of the lamp glass tube 300 according to the third embodiment of the present invention, even when soft glass such as soda glass or lead-free glass is used as the material, cracks are generated in the glass. Can be prevented. Further, even if the outer surface of the lamp glass tube 300 is slightly scratched, it is possible to prevent cracks due to the scratch. However, if the scratches increase or deepen, cracks may occur, but cracks in the glass tube 300 can be prevented in advance by visually recognizing and replacing the scratches on the outer surface of the glass tube 300. Can do.

(Fourth embodiment)
FIG. 11A shows a cross-sectional view including the tube axis X ₄₀₀ of the low-pressure discharge lamp according to the fourth embodiment of the present invention, and FIG. 11B shows an enlarged cross-sectional view of the principal part thereof. A low-pressure discharge lamp 400 (hereinafter simply referred to as “lamp 400”) according to the fourth embodiment of the present invention is a cold cathode fluorescent lamp, and the second embodiment of the present invention except for the glass bulb 401. The low-pressure discharge lamp according to FIG.

<Description of glass bulb>
The glass bulb 401 is obtained by processing the glass tube for lamp 300 according to the third embodiment of the present invention. The glass bulb 401 has a circular cross section cut perpendicular to the tube axis X ₄₀₀ and has a total length of 730 [ mm], the outer diameter is 4 [mm], the inner diameter is 3 [mm], and the wall thickness is 0.5 [mm].

<Summary>
As described above, according to the configuration of the low-pressure discharge lamp 400 according to the fourth embodiment of the present invention, even when a soft glass such as soda glass or lead-free glass is used as the material of the glass bulb 401, Generation of cracks can be prevented. Even if the outer surface of the glass bulb 401 is slightly scratched, it is possible to prevent damage due to the scratch. However, if the scratches increase or deepen, cracks may occur. However, by visually recognizing the scratches on the outer surface of the glass bulb 401 and replacing the lamp 400, the cracks in the glass bulb 401 are obviated. Can be prevented.

(Fifth embodiment)
FIG. 12A is a cross-sectional view including the tube axis X ₅₀₀ of the low-pressure discharge lamp according to the fifth embodiment of the present invention, FIG. 12B is an enlarged cross-sectional view of the main part of FIG. FIG. 12C shows an enlarged cross-sectional view of the main part of FIG. A low-pressure discharge lamp 500 (hereinafter simply referred to as “lamp 500”) according to the fifth embodiment of the present invention is an external electrode type fluorescent lamp. The lamp 500 includes a glass bulb 501 and external electrodes 502 formed on the outer surfaces of both ends thereof.

<Description of glass bulb>
The glass bulb 501 has an ion exchange layer 100a substantially the same as that of the glass tube 100 for a lamp according to the first embodiment of the present invention on its outer surface layer. The portion corresponding to the external electrode 502 also has an ion exchange layer 100a. Since the portion of the inner surface layer of the glass bulb 501 corresponding to the external electrode 502 is directly exposed to discharge when the lamp 500 is turned on, a pinhole is generated in the portion by the ion exchange layer 100a. Can be prevented.

Glass bulb 501 is a cross section annular shape cut in the vertical, for example with respect to the tube axis X _500, overall length 730 [mm], an outer diameter of 4 [mm], an inner diameter of 3 [mm], the thickness is 0 .5 [mm]. For example, both ends of the glass bulb 501 are sealed with glass beads 503. The glass bulb 501 can be sealed using various known methods such as a pinch seal method.

A phosphor layer 504 is formed on the inner surface of the glass bulb 501 except for the portion corresponding to the external electrode. The phosphor layer 504 includes, for example, a red phosphor (Y ₂ O ₃ : Eu ²⁺ ), a green phosphor (LaPO ₄ : Ce ³⁺ , Tb ³⁺ ), and a blue phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu ^{2). +} ) And a rare earth phosphor. A protective film (not shown) made of a metal oxide such as yttrium oxide (Y ₂ O ₃ ) may be formed between the inner surface of the glass bulb 501 and the phosphor layer 504.

  Inside the glass bulb 501, for example, about 2 [mg] mercury and a mixed gas of neon and argon (Ne95 [%] + Ar5 [%] of about 8 [kPa] (20 [° C.]) as a rare gas. ]) Are enclosed.

<Description of external electrode>
The external electrode 502 is made of, for example, an aluminum metal foil, and is attached so as to cover the outer peripheral surfaces of both ends of the glass bulb 501 with a conductive adhesive (not shown) in which metal powder is mixed with silicon resin. Yes.

  Note that a fluororesin, a polyimide resin, an epoxy resin, or the like may be used as the conductive adhesive instead of the silicon resin. Further, instead of sticking the metal foil to the glass bulb 501 with the conductive adhesive, the external electrode 502 may be formed by applying a silver paste to the entire circumference of the electrode forming portion of the glass bulb 501. In this case, it is possible to prevent the external electrode 502 from being peeled off due to deterioration of the conductive adhesive. In addition, when a solder film is formed on the external electrode 502, the external electrode 502 can be protected from damage. Further, it is possible to form the external electrode 502 with only a solder film by a known method such as ultrasonic solder dipping. The external electrode 502 of the lamp 500 shown in FIG. 12A is not formed up to the tube end of the glass bulb 501, but is formed in a headband shape so as to cover the entire tube end of the glass bulb 501. An external electrode 502 may be formed.

  Alternatively, the external electrode 502 may be formed by covering a metal sleeve made of an alloy of iron and nickel, for example, and performing a solder dipping process thereon.

<Summary>
As described above, according to the configuration of the low-pressure discharge lamp 500 according to the fifth embodiment of the present invention, even when soft glass such as soda glass or lead-free glass is used as the material of the glass bulb 501, the glass bulb 501 is used. Generation of cracks can be prevented. Furthermore, it is possible to prevent the occurrence of pinholes at the corresponding portions of the external electrodes in the glass bulb 501 during discharge.

(Sixth embodiment)
FIG. 13 shows an exploded perspective view of a backlight unit 600 according to the sixth embodiment of the present invention. The backlight unit 600 according to the sixth embodiment of the present invention is a direct type, and has a rectangular parallelepiped housing 601 with one surface opened, and a plurality of lamps 200 housed in the housing 601. A pair of sockets 602 for electrically connecting the lamp 200 to a lighting circuit (not shown) and an optical sheet 603 covering the opening of the housing 601 are provided. The lamp 200 is the low-pressure discharge lamp 200 according to the second embodiment of the present invention.

<Description of the housing>
The housing 601 is made of, for example, polyethylene terephthalate (PET) resin, and a reflective surface 604 is formed by depositing a metal such as silver on the inner surface thereof. In addition, as a material of the housing | casing 601, 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 reflective surface 604 on the inner surface, other than a metal vapor deposition film, for example, a sheet in which a reflective sheet with increased reflectance by adding calcium carbonate, titanium dioxide or the like to polyethylene terephthalate (PET) resin is attached to the housing 601. It may be used.

  Inside the housing 601, a socket 602, an insulator 605, and a cover 606 are disposed. Specifically, the sockets 602 are provided at predetermined intervals in the lateral direction (vertical direction) of the housing 601 corresponding to the arrangement of the lamps 200. The socket 602 is obtained by processing a plate material made of stainless steel or phosphor bronze, for example, and has a fitting portion 602a into which the lead wire 202 is fitted. Then, the lead wire 202 is fitted by being elastically deformed so as to expand the fitting portion 602a. As a result, the lead wire 202 fitted in the fitting part 602a is pressed by the restoring force of the fitting part 602a and is difficult to come off. Accordingly, the lead wire 202 can be easily fitted into the fitting portion 602a, but can be made difficult to come off.

  The socket 602 is covered with an insulator 605 so as not to short-circuit between adjacent sockets 602. The insulator 605 is made of, for example, polyethylene terephthalate (PET) resin. Note that the insulator 605 is not limited to the above structure. Since the socket 602 is in the vicinity of the internal electrode 3 that becomes relatively hot during operation of the lamp 200, the insulator 605 is preferably made of a heat-resistant material. As a material for the heat-resistant insulator 605, for example, polycarbonate (PC) resin, silicon rubber, or the like can be used.

  Inside the housing 601, a lamp holder (not shown) may be provided at a place as necessary. The lamp holder that fixes the position of the lamp 200 inside the housing 601 is, for example, polycarbonate (PC) resin, and has a shape that follows the outer shape of the lamp 200. The “location as necessary” means that the deflection of the lamp 200 is caused when the lamp 200 has a long length exceeding, for example, 600 [mm], as in the vicinity of the central portion of the lamp 200 in the longitudinal direction. It is a place necessary to eliminate.

  The cover 606 divides the socket 602 and the space inside the housing 601 and is made of, for example, polycarbonate (PC) resin, keeps the periphery of the socket 602 warm, and highly reflects at least the surface on the housing 601 side. By reducing the brightness, a decrease in luminance at the end of the lamp 200 is reduced.

<Description of optical sheets>
The opening of the housing 601 is covered with a light-transmitting optical sheet 603 and is sealed so that foreign matters such as dust and dust do not enter inside. The optical sheet 603 is formed by laminating a diffusion plate 607, a diffusion sheet 608, and a lens sheet 609.

  The diffusion plate 607 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 601. The diffusion sheet 608 is made of, for example, a polyester resin. The lens sheet 609 is, for example, a laminate of an acrylic resin and a polyester resin. These optical sheets 603 are arranged so as to be sequentially superimposed on the diffusion plate 607.

<Summary>
As described above, according to the configuration of the backlight unit 600 according to the sixth embodiment of the present invention, even when soft glass such as soda glass or lead-free glass is used as the material of the glass bulb 201 of the low-pressure discharge lamp 200. It is possible to prevent the glass bulb 201 from cracking.

(Seventh embodiment)
FIG. 14 shows a partially cutaway perspective view of a backlight unit according to the seventh embodiment of the present invention. The backlight unit 700 according to the seventh embodiment of the present invention is an edge light system, and includes a reflection plate 701, a lamp 200, a socket (not shown), a light guide plate 702, a diffusion sheet 703, and a prism sheet 704. Yes.

  The reflection plate 701 is disposed so as to surround the periphery of the light guide plate 702 excluding the liquid crystal panel side (arrow Q), and the side surface covering the bottom surface portion 701b covering the bottom surface and the side surface excluding the side where the lamp 200 is disposed. 701a and a curved lamp side surface portion 701c covering the periphery of the lamp 200, and reflects light emitted from the lamp from the light guide plate 702 to the liquid crystal panel (not shown) side (arrow Q). . Further, the reflecting plate 701 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 602 used in the backlight unit 600 according to the sixth embodiment of the present invention. In FIG. 14, the end of the lamp 200 is omitted for convenience of illustration.

  The light guide plate 702 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 laminated on the reflection plate 701 provided on the bottom surface of the backlight unit 700. Has been. As a material, polycarbonate (PC) resin or cycloolefin-based resin (COP) can be applied.

  The diffusion sheet 703 is for expanding the visual field and is made of, for example, a film having a diffusion transmission function made of polyethylene terephthalate resin or polyester resin, and is laminated on the light guide plate 702.

  The prism sheet 704 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 703. A diffusion plate may be further laminated on the prism sheet 704.

  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 200 (the light guide plate 702 side when inserted into the backlight unit 700). Aperture type lamps may also be used.

<Summary>
As described above, according to the configuration of the backlight unit 700 according to the sixth embodiment of the present invention, even when soft glass such as soda glass or lead-free glass is used as the material of the glass bulb 201 of the low-pressure discharge lamp 200. It is possible to prevent the glass bulb 201 from cracking.

(Eighth embodiment)
FIG. 15 shows an outline of a liquid crystal display device according to the eighth embodiment of the present invention. As shown in FIG. 15, the liquid crystal display device 800 is, for example, a 32 [inch] television, and includes a liquid crystal screen unit 801 including a liquid crystal panel and the like, a backlight unit 600 according to the sixth embodiment of the present invention, and a lighting circuit 802. Prepare.

  The liquid crystal screen unit 801 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 802 lights the lamp 200 inside the backlight unit 600. The lamp 200 is operated at a lighting frequency of 40 [kHz] to 100 [kHz] and a lamp current of 3 [mA] to 25 [mA].

  In FIG. 8, the case where the low-pressure discharge lamp 200 according to the second embodiment is inserted into the backlight unit 600 according to the sixth embodiment of the present invention as the light source device of the liquid crystal display device 800 has been described. Not limited to this, the low-pressure discharge lamp 400 according to the fourth embodiment of the present invention and the low-pressure discharge lamp 500 according to the fifth embodiment of the present invention can also be applied. Further, the backlight unit 700 according to the seventh embodiment of the present invention can also be used for the backlight unit.

<Summary>
As described above, according to the configuration of the liquid crystal display device according to the eighth embodiment of the present invention, even when soft glass such as soda glass or lead-free glass is used as the material of the glass bulb 201 of the low-pressure discharge lamp 200, It is possible to prevent the glass bulb 201 from cracking.

<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. Glass used for lamp glass tube and glass bulb (1) UV absorption 254 [nm] by doping a glass, which is a material of lamp glass tube 100, 300, with an oxide of a transition metal depending on its type. And 313 [nm] ultraviolet rays can be absorbed. 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 of 254 [nm] can be absorbed by doping at 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 fluorescent lamp (EEFL) or a long cold cathode fluorescent 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.

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: Thickness of glass (3) Shape of glass tube for lamp and glass bulb The shape of glass tube for lamp 100, 300 and glass bulb 201, 401, 501 is not limited to a straight tube shape, for example, L-shape , U-shape, U-shape, spiral shape, etc. 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) About ultraviolet 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 rays having a wavelength of 313 [nm] may be used. The following phosphors absorb 313 [nm] ultraviolet rays.

(A) barium strontium magnesium active aluminate with blue, europium manganese co _{[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)
Note that phosphors of different compounds may be mixed and used for one kind of emission 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 105 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 that excitation light is emitted 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 is performed as part of the improvement in image quality. There is a need to expand the reproducible chromaticity range in cathode fluorescent lamps and external electrode fluorescent 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 = 0.56).

  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 the NTSC triangle (NTSC triangle) connecting the chromaticity coordinate values of the three primary colors of the NTSC standard in the CIE1931 chromaticity diagram. A triangular area ratio formed by connecting chromaticity coordinate values (hereinafter referred to as NTSC ratio) is used.

  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 low-pressure discharge lamp according to each of the above embodiments, the glass bulb has the phosphor layer on the inner surface. For example, the lamp is an ultraviolet lamp not provided with a phosphor layer. Also good.

  The low-pressure discharge lamp is not limited to a cold cathode fluorescent lamp or an external electrode fluorescent lamp, and may be a hot cathode fluorescent lamp or an external internal electrode fluorescent lamp.

  The present invention can be widely applied to glass tubes for lamps, low-pressure discharge lamps, backlight units, and liquid crystal display devices.

(A) Sectional drawing including the tube axis | shaft of the glass tube for lamps concerning the 1st Embodiment of this invention, (b) The principal part expanded sectional view of A part of Fig.1 (a). (A) Conceptual diagram of immersion process of ion exchange treatment of glass tube for lamp, (b) Conceptual diagram of cleaning process, (c) Conceptual diagram of drying process (A) Image figure in the principal part expanded cross section of the outer surface layer of the glass tube for lamps of the initial stage of immersion process, (b) Image figure in the principal part enlarged cross section of the outer surface layer of the glass tube for lamps in the last stage of immersion process Conceptual diagram for explaining destructive test conditions (A1) A diagram showing the concentration distribution of sodium in the outer surface layer of the glass tube B, (a2) A diagram showing the concentration of sodium in the outer surface layer of the glass tube A ₁ , (a3) of the outer surface layer of the glass tube A ₂ It shows the concentration of sodium, (a4) shows the concentration of sodium in the outer surface layer of the glass tube a _3, (b1) shows the concentration of potassium in the outer surface layer of the glass tube B, (b2) a glass tube a ₁ is a diagram showing the concentration of potassium in the outer surface layer of FIG. 1, (b3) is a diagram showing the concentration of potassium in the outer surface layer of the glass tube A ₂ , and (b4) is a diagram showing the concentration of potassium in the outer surface layer of the glass tube A ₃ . The figure for explaining the measurement method of the potassium concentration of the ion exchange layer (A) Sectional drawing including the tube axis of the low-pressure discharge lamp concerning the 2nd Embodiment of this invention, (b) The principal part expanded sectional view of B part of Fig.7 (a). (A) Sectional drawing including the tube axis of the glass tube for lamps concerning the 3rd Embodiment of this invention, (b) The principal part expanded sectional view of C part of Fig.8 (a). (A) The conceptual diagram of the 1st immersion process of the ion exchange process of the glass tube for lamps, (b) The conceptual diagram of the 1st washing process, (c) The conceptual diagram of the 1st drying process, (d) The 2nd Schematic diagram of immersion process, (e) Schematic diagram of second cleaning process, (f) Schematic diagram of second drying process (A) Image diagram in the main part enlarged cross section of the outer surface layer of the glass tube for lamps in the initial stage of the first immersion process, (b) Image diagram in the main part enlarged cross section of the outer surface layer of the glass tube for lamps in the final stage of the first immersion process, (C) Image diagram of an enlarged cross-section of the main part of the outer surface layer of the glass tube for a lamp at the end of the second immersion process (A) Sectional drawing including the tube axis of the low-pressure discharge lamp concerning the 4th Embodiment of this invention, (b) The principal part expanded sectional view of D part of Fig.11 (a). (A) Cross-sectional view including the tube axis of the low-pressure discharge lamp according to the fifth embodiment of the present invention, (b) an enlarged cross-sectional view of an essential part of the E portion in FIG. 12 (a), (c) FIG. The principal part expanded sectional view of F part of The disassembled perspective view of the backlight unit which concerns on the 6th Embodiment of this invention. The disassembled perspective view of the backlight unit which concerns on the 7th Embodiment of this invention. Schematic perspective view of a liquid crystal display device according to an eighth embodiment of the present invention. Sectional view including the tube axis of a conventional low-pressure discharge lamp

Explanation of symbols

100,300 Glass tube for lamp 100a, 300a Ion exchange layer 200,400,500 Low pressure discharge lamp 201,401,501 Glass bulb 300b First ion exchange layer 300c Second ion exchange layer 600,700 Backlight unit 800 Liquid crystal display device

Claims (13)

A glass tube for a lamp having a thermal expansion coefficient of 60 [K ^-1 ] to 110 [K ^-1 ] and at least an outer surface layer thereof being an ion exchange layer. 2. The lamp for a lamp according to claim 1, wherein the concentration of an alkali metal having an ionic radius larger than that of sodium in the ion exchange layer is higher than a concentration of an alkali metal having an ionic radius larger than that of sodium in the non-ion exchange layer. Glass tube. The glass tube for a lamp according to claim 2, wherein the alkali metal is potassium. The glass tube for a lamp according to any one of claims 1 to 3, wherein a thickness of the ion exchange layer is 5 [µm] or more. The ion exchange layer comprises two layers, a first ion exchange layer and a second ion exchange layer located outside the first ion exchange layer, and an alkali metal having a larger ion radius than sodium in the first ion exchange layer. Is higher than the concentration of alkali metal having a larger ion radius than sodium in the non-ion exchange layer, and the concentration of alkali metal in the second ion exchange layer is lower than the concentration of alkali metal in the first ion exchange layer. The glass tube for a lamp according to claim 1, wherein: The glass tube for a lamp according to any one of claims 1 to 5, wherein the boron oxide content is in the range of 0 [mol%] to 5 [mol%]. The glass tube for a lamp according to any one of claims 1 to 6, wherein the content of alumina is in the range of 0 [mol%] to 5 [mol%]. The total content of alkali metal oxides and alkaline earth metal oxides is in the range of 10 [mol%] to 30 [mol%], and the total content of strontium oxide and barium oxide is 0 [ The glass tube for a lamp according to any one of claims 1 to 7, which is in a range of not less than mol%] and not more than 12 [mol%]. The inner diameter is 1 [mm] or more and 8 [mm] or less, the thickness is 0.2 [mm] or more and 0.6 [mm] or less, and the length is 300 [mm] or more and 2000 [mm] or less. The glass tube for lamps of any one of these. A first ion exchange layer forming step including a step of immersing at least a glass tube in a molten salt of an alkali metal having an ionic radius larger than that of sodium; and a glass tube that has undergone at least the first ion exchange layer forming step as the first ion exchange. The manufacturing method of the glass tube for lamps characterized by including the 2nd ion exchange layer formation process including the process of immersing in the molten salt of the alkali metal whose ion radius is smaller than the alkali metal used at the layer formation process. A low-pressure discharge lamp using the glass tube for a lamp according to any one of claims 1 to 9 as a glass bulb. A backlight unit comprising the low-pressure discharge lamp according to claim 11. A liquid crystal display device comprising the backlight unit according to claim 12.

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