JP2008251429A - 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 improving dark starting characteristic of a low-voltage discharge lamp without being adversely affected by vibration or impact accompanying transportation or the like, to provide a low-pressure discharge lamp, to provide a backlight unit, and to provide a liquid crystal display. <P>SOLUTION: For the glass tube 100 with an ion exchange layer 100a formed on an inner surface layer, a density of alkali metal with an ion radius larger than that of sodium in the ion exchange layer 100a is higher than a density of alkali metal with an ion radius larger than that of sodium in an non-ion exchange layer 100b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

22A and 22B are cross-sectional views including a central axis X ₁ in the longitudinal direction of a conventional low-pressure discharge lamp, for example, a cold cathode fluorescent lamp 1 (hereinafter simply referred to as “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 external light in a backlight unit mounted on a liquid crystal display device is scarce. There is a need for improved starting characteristics (improvement of dark starting characteristics). In order to make this possible, a cesium compound 4 is deposited inside the glass bulb 2 (see, for example, Patent Document 1).
JP 2001-15065 A

  However, as shown in FIG. 22A, when the cesium compound 4 is deposited on the surface of the electrode 3, the cesium compound 4 is detached from the electrode 3 due to vibration or impact associated with the transportation of the lamp 1 or the like. There is a risk that.

  Further, as shown in FIG. 22B, even when the cesium compound 4 is attached to the inner surface of the end portion of the glass bulb 2, the cesium compound 4 is caused by vibration or impact accompanying the transportation of the lamp 1. There is a risk of falling off the glass bulb 2. Furthermore, in order to deposit the cesium compound 4 on that portion, after sealing the end portion on the side to which the cesium compound 4 is attached, the cesium compound 4 must be attached from the opposite end portion, The process takes time.

  Accordingly, the present invention provides a glass tube for a lamp, a low-pressure discharge lamp, a backlight unit, and a liquid crystal display device capable of improving the dark starting characteristics of a low-pressure discharge lamp without being affected by vibrations and shocks associated with transportation and the like. The purpose is to do.

  In order to solve the above problems, a glass tube for a lamp according to the present invention is a glass tube in which an ion exchange layer is formed on an inner surface layer, and an alkali metal having an ion radius larger than sodium in the ion exchange layer. The concentration of is higher than the concentration of alkali metal having a larger ionic radius than sodium in the non-ion exchange layer.

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

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

  In the glass tube for a lamp according to the present invention, the outer surface layer has a concentration of an alkali metal having an ionic radius larger than that of sodium and a concentration of an alkali metal having a larger ionic radius than that of sodium in the non-ion exchange layer. The ion exchange layer is preferably formed.

  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 low-pressure discharge lamp according to the present invention uses the lamp glass tube as a glass bulb.

  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 can improve the dark starting characteristics of the low-pressure discharge lamp without being affected by vibrations and shocks associated with transportation and the like.

(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). A glass tube 100 for a lamp according to the first embodiment of the present invention (hereinafter simply referred to as “glass tube 100”) includes an ion exchange layer 100a in which a part of an inner surface layer is formed by an ion exchange process described later, And a non-ion exchange layer 100b having an original glass composition that is not ion-exchanged.

<Description of ion exchange layer>
In the ion exchange layer 100a, the concentration of the alkali metal having an ionic radius larger than that of sodium is higher than that of the sodium in the non-ion exchange layer 100b. Hereinafter, the formation process of the ion exchange layer 100a is demonstrated about the case where cesium is used as an alkali metal with an ionic radius larger than sodium. An image diagram of the process of forming the ion exchange layer 100a is shown in FIG.

<Immersion process>
First, as shown in FIG. 2A, a glass tube 101 before ion exchange treatment (hereinafter simply referred to as “glass tube 101”) is prepared. The glass tube 101 has a composition shown in Table 1, for example, having 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]. Using.

The glass tube 101 is immersed in a bath 103 containing a cesium nitrate (CsNO ₃ ) molten salt 102 heated to 350 [° C.] to 450 [° C.], for example, 120 [min] to 240 [min]. The film thickness of the ion exchange layer 100a can be changed according to the time for immersing the glass tube 101 in the molten cesium nitrate. By the way, when only ion exchange of the inner surface layer of the glass tube 101 is carried out, for example, soda glass lids are put on the openings at both ends after cesium nitrate is put into the glass tube 101, and the inside of the glass tube 101 is sealed. It is preferable to heat to 350 [° C.] to 450 [° C.] in a furnace. Thereby, solid cesium nitrate inside the glass tube 101 becomes a liquid cesium nitrate molten salt 102, and the ion exchange layer 100 a can be formed only on the inner surface layer of the glass tube 101. Note that both ends of the glass tube 101 may be sealed with a gas burner or the like instead of covering the openings 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 in a bath 105 containing water 104, so that excess cesium nitrate molten salt 102 adhering to the surface of the glass tube 100 is removed. Remove.

<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.

<Image of ion exchange layer formation>
FIG. 3A is an image view of an enlarged section of the main surface layer of the inner surface layer of the glass tube 101 at the initial stage of the dipping process, and FIG. 3B is an image diagram of an enlarged section of the main portion of the inner surface layer of the glass tube 100 at the end of the dipping process. Respectively. As shown in FIG. 3A, in the initial stage of the dipping process, sodium ions (Na ⁺ ) are distributed on the inner surface layer of the glass tube 101 in the same manner as other portions of the glass tube 101. Then, as shown in FIG. 3B, at the end of the dipping process, a part of sodium ions is exchanged with cesium ions (Cs ⁺ ) contained in the molten cesium nitrate salt 102, and the inner surface layer of the glass tube 100 More cesium ions are distributed in the glass tube 100 than in other portions. Therefore, when this glass tube 100 is used for a low pressure discharge lamp, the dark starting characteristics of the low pressure discharge lamp can be improved by cesium present in the ion exchange layer 100a. The dark starting characteristics when the lamp glass tube 100 is used in a low-pressure discharge lamp will be described in detail later along with experiments in the second embodiment of the present invention.

  Moreover, the ionic radius of a cesium ion is larger than the ionic radius of a sodium ion. Therefore, when the sodium ions are exchanged for cesium ions, the cesium ions having a larger ion radius than the sodium ions are accommodated in the portion where the sodium ions having a smaller ion radius are accommodated. Compressive stress will act on. By forming the ion exchange layer 100a on which the compressive stress works on the outer surface layer of the glass tube 100, the glass tube 100 becomes strong against an impact from the outside, and the mechanical strength of the glass tube 100 is improved. be able to.

<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. Further, since the ion exchange layer 100a is merely formed on the inner 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.

  Here, the composition of the non-ion exchange layer 100b is not limited to that shown in Table 1, but the sodium oxide content of the non-ion exchange layer 100b is particularly 5 [mol%] or more and 15 [mol%]. It is preferable to be within the following range. In this case, since the ion exchanged sodium is sufficiently contained in the glass tube 101, the ion exchange layer 100a can be easily formed.

Further, it is preferred that the non-content of boron oxide of the ion-exchange layer 100b (B ₂ O ₃₎ is in the range of 0 [mol%] or more 5 [mol%] or less. In this case, by suppressing the amount of boron that suppresses the precipitation of sodium, the behavior of sodium ions in the glass tube 101 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 101 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 the precipitation of sodium, the behavior of sodium ions in the glass tube 101 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 101 other than aluminum, 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, part of boron in the glass tube 101 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 101, for example, 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 ion radius than sodium ions, the sodium ions are prevented from moving from the inside of the glass tube 101 to the outside, thereby preventing the formation of the ion exchange layer 100a. Can be prevented.

<Summary>
As described above, according to the configuration of the glass tube for a lamp according to the first embodiment of the present invention, even when used for a low-pressure discharge lamp, the darkness of the low-pressure discharge lamp is not affected by vibrations and impacts associated with transportation and the like. The starting characteristics can be improved.

  In the present embodiment, cesium has been described in detail as an alkali metal having an ionic radius larger than that of sodium, but an alkali metal such as potassium (K) can also be applied.

(Second Embodiment)
FIG. 4A 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. 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 inner electrode 202 is connected to the inner electrode 202, and the other end is led out from the tube end of the glass bulb 201 to the outside.

<Description of glass bulb>
The glass bulb 201 is obtained by processing the lamp glass tube 100 according to the first embodiment of the present invention. The glass bulb 201 has a circular cross section cut perpendicular to the tube axis 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 204. The glass bulb 201 can be sealed using various known methods such as a pinch seal method.

A phosphor layer 205 is formed on the inner surface of the glass bulb 201. The phosphor layer 205 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 205 closer to this end, that is, the length of the region of the glass bulb 201 where the phosphor layer 205 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 narrow, it is difficult to form the phosphor layer 205 having a uniform film thickness on the inner surface of the glass bulb 201. That is, the thickness of the phosphor layer 205 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 205 closer to this end. A way to do this is conceivable. The difference in distance is preferably 2 [mm] or more. This is because the length is sufficiently distinguishable by a general sensor and almost no identification error occurs.

In addition, between the inner surface of the glass bulb 201 and the phosphor layer 205, 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 202 is a bottomed cylindrical hollow electrode made of, for example, nickel (Ni), 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 202 is not limited to nickel, and may be, for example, niobium (Nb), tantalum (Ta), molybdenum (Mo), or tungsten (W). The internal electrode 202 is disposed so that the tube axis thereof and the tube axis of the glass bulb 201 substantially coincide 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 202 and the inner surface of the glass bulb 201 is preferably 0.2 [mm] or less, for example, set to 0.15 [mm]. By defining the interval to be 0.2 [mm] or less in this way, during lighting, discharge does not enter the space formed between the outer surface of the internal electrode 202 and the inner surface of the glass bulb 201, and the internal electrode 202 Discharge occurs only inside. Therefore, it becomes difficult for the discharge during lighting to shift to the outside of the internal electrode 202, and it is possible to suppress excessive sputtering on the inner surface of the glass bulb 201 and suppress the consumption rate of mercury, thereby extending the life of the lamp 200. Can be planned. Further, by preventing the discharge from wrapping around the lead wire 203, the consumption of the lead wire 203 can be suppressed.

<Description of lead wire>
The lead wire 203 is composed of a joint between an internal lead wire 203a made of, for example, Dumet and an external lead wire 203b made of nickel (Ni) that easily adheres to solder or the like, and is joined to the internal lead wire 203a and the external lead wire 203b. The surface is substantially flush with the outer surface of the glass bulb 201. That is, one end of the internal lead wire 203a is electrically and mechanically connected to the bottom of the hollow internal electrode 202, and most of the other end side connected to the external lead wire 203b is the glass bead 204. Is sealed. The external lead wire 203b is substantially entirely located outside the glass bulb 201. The internal lead wire 203a has, for example, a total length of 3 [mm] and a wire diameter of 1.0 [mm]. The external lead wire 203b has, for example, a total length of 10 [mm] and a wire diameter of 0.8 [mm].

  The configuration of the lead wire 203 is not limited to the above configuration. For example, the internal lead wire 203a and the external lead wire 203b are not separated, and may be configured by a single wire made of an alloy of iron and nickel. Alternatively, the internal lead wire 203a or the external lead wire 203b may further connect a plurality of wires.

<Experiment>
The inventors conducted an experiment to compare the dark starting characteristics of the lamps A ₁ , A ₂ , A ₃ produced using the glass tube subjected to the ion exchange treatment and the lamp B produced using the untreated glass tube. went.

The glass materials of the glass bulbs of the lamps used in the experiment are all lead-free glass shown in Table 1 as glass a, and the outer diameter is 4.0 [mm] and the inner diameter is 3.0 [mm]. The total length in a state of sealing is 232 [mm]. In performing the ion exchange treatment, the ion exchange treatment was performed by immersing in a molten potassium nitrate salt at a heating temperature of about 540 [° C.] in the state of the glass tube before sealing. However, the lamps A ₁ , A ₂ and A ₃ differ only in the immersion time as follows.

(1) Lamp A ₁ : Immersion time 120 [min]
(2) Lamp A ₂ : immersion time 180 [min]
(3) Lamp A ₃ : immersion time 240 [min]
(4) Lamp B: No ion exchange treatment In the experiment, the dark starting characteristics were measured by starting and lighting under dark conditions using four types of lamps A ₁ , A ₂ , A ₃ and B. The lamp was started under the condition of 41.5 [h] at room temperature in the dark and then lit in the dark state under 0.1 [Lux]. Then, the time (dark start time) from the start of applying a voltage to the lamp until the current flows through the lamp was measured with an oscilloscope.

  Table 2 shows the measurement results in the above experiment.

As shown in Table 2, the dark start times of lamp A ₁ , lamp A ₂ and lamp A ₃ were all shorter than the dark start time of lamp B. This is considered to be because the initial electrons required for the start of discharge are emitted from cesium contained in the ion exchange layer formed on the inner surface layer of the glass tube 100, and the dark start-up characteristics are improved.

The dark start times of the lamp A ₁ , the lamp A ₂ and the lamp A ₃ were not significantly different. Therefore, it is considered that the thickness of the ion exchange layer does not greatly affect the dark start time.

  By the way, in particular, the ion exchange layer 100a is at least an inner surface layer of the glass bulb 201 and a portion corresponding to the internal electrode 202 (corresponding portion s in FIG. 4A) as shown in FIG. ). This is because the electric field strength at the position of the corresponding portion s is strong on the inner surface of the glass bulb 201 in the lamp 200, and it is easy to contribute to the improvement of the dark starting characteristics. Further, the ion exchange layer 100a is at least the inner surface layer of the glass bulb 201, and a region from the edge of the internal electrode 202 on the central portion side of the lamp 200 to the central portion in the longitudinal direction of the internal electrode 202, that is, a corresponding portion. More preferably, it is formed in a region of 1 / 2s with respect to s. This is because the electric field strength is higher in the corresponding portion s of the internal electrode 202 in the inner surface layer of the glass bulb 201, and it is easier to contribute to the improvement of the dark starting characteristics.

  In addition, it is preferable not to form the fluorescent substance layer 205 in the part in which the ion exchange layer 100a is formed. This is because the phosphor layer 205 may inhibit electron emission.

<Summary>
As described above, according to the configuration of the low-pressure discharge lamp 200 according to the second embodiment of the present invention, it is possible to improve the dark starting characteristics without being affected by vibrations and impacts associated with transportation and the like.

(Third embodiment)
FIG. 5A shows a cross-sectional view including the tube axis X ₃₀₀ of the low-pressure discharge lamp according to the third embodiment of the present invention, and FIG. The low-pressure discharge lamp (hereinafter simply referred to as “lamp 300”) according to the third embodiment of the present invention is a cold cathode fluorescent lamp having external connection terminals 301 on the outer peripheral surfaces of both end portions of the glass bulb 201. Since the configuration of the lamp 300 other than the external connection terminal 301 is substantially the same as that of the low-pressure discharge lamp 200 according to the second embodiment of the present invention, the external connection terminal will be described in detail, and other points will be described. Omitted.

<Description of external connection terminal>
The external connection terminal 301 is provided so as to cover the outer peripheral surfaces of both ends of the glass bulb 201. The external connection terminal 301 is made of, for example, solder and joined to the external lead wire 203b.

  In general, solder is suitable as a material for the external connection terminal 301 because it has good conductivity, low thermal conductivity, and low price. In particular, a solder mainly composed of tin (Sn), an alloy of tin and indium (In), an alloy of tin and bismuth (Bi), or the like can form the external connection terminal 301 having high mechanical strength. Therefore, it is more preferable. Among them, among antimony (Sb), zinc (Zn), aluminum (Al), gold (Au), silver (Ag), copper (Cu), iron (Fe), platinum (Pt) and palladium (Pd) The solder to which at least one kind is added has good compatibility with glass, and thus can form the external connection terminal 301 that is difficult to peel off from the glass bulb 201, and is more preferable. In addition, solder containing no lead is preferable because the lamp 300 can be manufactured in consideration of the environment. The material for forming the external connection terminal 301 is not limited to solder, and may be any material having at least conductivity.

  In FIG. 5A, the surface of the external lead wire 203 b is covered with the external connection terminal 301, but the external lead wire 203 b may protrude from the external connection terminal 301. Moreover, the external connection terminal 301 does not necessarily need to be provided in the both ends of the glass bulb 201, and may be provided only in one side.

As shown in FIG. 6, the external connection terminal 303 of the lamp 302 may be composed of a sleeve 303a made of an alloy of Fe and Ni, and solder 303b. The sleeve 303a, for example, in its wall thickness is section cut vertically formed in a substantially C-shape to the tube axis X ₃₀₂ is 120 [[mu] m], in the cylindrical body of length in the longitudinal direction 10 [mm] Thus, it is fitted on the end of the glass bulb 201. The inner diameter of the sleeve 303a is preferably slightly smaller than the outer diameter of the glass bulb 201. In this case, even if a slight dimensional error occurs between the inner diameter of the sleeve 303 a and the outer diameter of the glass bulb 201, the sleeve 303 a can be expanded and the inner surface of the sleeve 303 a can be brought into close contact with the outer surface of the glass bulb 201. .

  The sleeve 303a is not limited to a cylindrical body having a substantially C-shaped cross section cut perpendicular to the tube axis, but is a polygonal cylindrical body such as a substantially triangular shape or a substantially rectangular shape, or an elliptical cylindrical shape. The body may be provided with slits.

<Position of ion exchange layer>
In the case of the lamps 300 and 302, the ion exchange layer 100a is at least the inner surface layer of the glass bulb 201 and the region v [of the central portion of the glass bulb 201 with respect to the external connection terminals 301 and 303 for the following reason. It is preferably formed in FIG. 5 (a) and FIG.

  In the cold cathode fluorescent lamp, when a negative voltage is applied to the internal electrode 202 during startup, ions in the glass bulb 201 are accelerated by an electric field between the internal electrode 202 and a nearby conductor such as a bottom plate of a lighting device. Then, it collides with the internal electrode 202 and generates secondary electrons. Then, discharge starts from the secondary electrons. However, in the lamps 300 and 302, the distance between the external connection terminals 301 and 303 and the proximity conductor is shorter than the distance between the internal electrode 202 and the proximity conductor, and the internal electrode 202 and the external connection terminals 301 and 303 have the same potential. Therefore, an electric field having a high strength is generated between the external connection terminals 301 and 303 and the adjacent conductor, and an electric field strength between the internal electrode 202 and the external connection terminals 301 and 303 is lowered. Since the acceleration action of electrons inside 201 is weakened, it is difficult for discharge to occur, and the dark startability is deteriorated. As shown in FIGS. 5A and 6, when the external connection terminals 301 and 303 are extended in the tube axis direction of the glass bulb 201 to cover the entire internal electrode 202, the external connection terminals 301 and 303 are obstructive. Thus, the dark start-up characteristic deteriorates as the electric field strength between the internal electrode 202 and the adjacent conductor becomes further lower and lighting becomes difficult.

  Therefore, by providing an ion exchange layer in the region v on the inner surface layer of the glass bulb 201 having a high electric field strength and on the central side of the glass bulb 201 with respect to the external connection terminals 301 and 303, the lamps 300 and 302 are provided. It is possible to improve the dark start-up characteristics. The length in the tube axis direction of the region v is, for example, 4 [mm] or less, and it is preferable that the phosphor layer 205 is not formed thereon. This is because if the length of the region v in the tube axis direction is long and the phosphor layer 205 is not formed thereon, the effective light emission length is shortened.

<Summary>
As described above, according to the configuration of the low-pressure discharge lamp according to the third embodiment of the present invention, it is possible to improve the dark start characteristic without being affected by vibrations and impacts associated with transportation and the like.

(Fourth embodiment)
FIG. 7A 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. A low-pressure discharge lamp 400 (hereinafter simply referred to as “lamp 400”) according to the fourth embodiment of the present invention is an external electrode type fluorescent lamp. The lamp 400 includes a glass bulb 401 and external electrodes 402 formed on the outer surfaces of both ends thereof.

<Description of glass bulb>
The glass bulb 401 has an ion exchange layer 100a that is substantially the same as the glass bulb 201 of the low-pressure discharge lamp according to the first embodiment of the present invention at the inner surface layer corresponding to the external electrode 402. .

  For example, the glass bulb 401 has an annular cross section cut perpendicular to the tube axis, 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]. For example, both ends of the glass bulb 401 are sealed with glass beads 403. The glass bulb 401 can be sealed using various known methods such as a pinch seal method.

A phosphor layer 404 is formed on the inner surface of the glass bulb 401 except for the portion corresponding to the external electrode 402. The phosphor layer 404 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 401 and the phosphor layer 404.

  Inside the glass bulb 401, 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 402 is made of, for example, aluminum metal foil, and is adhered so as to cover the outer peripheral surfaces of both ends of the glass bulb 401 with a conductive adhesive (not shown) in which metal powder is mixed with silicon resin. .

  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 401 with the conductive adhesive, the external electrode 402 may be formed by applying a silver paste to the entire circumference of the electrode forming portion of the glass bulb 401. In this case, it is possible to prevent the external electrode 402 from peeling off due to deterioration of the conductive adhesive. In addition, when a solder film is formed on the external electrode 402, the external electrode 402 can be protected from damage. Further, it is possible to form the external electrode 402 with only a solder film by a known method such as ultrasonic solder dipping. The external electrode 402 of the lamp 400 shown in FIG. 7A is not formed up to the tube end of the glass bulb 401 but is formed in a headband shape so as to cover the entire tube end of the glass bulb 401. An external electrode 402 may be formed.

  Alternatively, the external electrode 402 may be formed by covering a metal sleeve made of, for example, an alloy of iron and nickel and performing a solder dipping process thereon.

<Summary>
As described above, according to the configuration of the low-pressure discharge lamp 400 according to the fourth embodiment of the present invention, a cesium compound is attached to a portion corresponding to the external electrode 402 on the inner surface of the glass bulb 401 or mixed into the protective film. Thus, it is possible to improve the dark start characteristics without being attached to the inner surface of the glass bulb 401.

(Fifth embodiment)
Figure 8 is a sectional view including the tube axis X ₅₀₀ of the glass tube lamp according to a fifth embodiment of the present invention (a), the enlarged sectional view of the E portion in FIG. 8 (b), the F The principal part expanded sectional view of a part is shown in FIG.8 (c), respectively. As shown in FIG. 8B, a lamp glass tube 500 according to the fifth embodiment of the present invention (hereinafter simply referred to as “glass tube 500”) has an ion exchange layer 100a formed on its inner surface layer. 8C, another ion exchange layer 500a is formed on the outer surface layer, and the ion exchange layer 100a, another ion exchange layer 500a, and a non-ion exchange layer in which no ion exchange layer is formed. 100b. In addition, since it has the structure substantially the same as the glass tube 100 for lamp | ramps which concerns on the 1st Embodiment of this invention other than another ion exchange layer 500a, about another ion exchange layer 500a in detail. It will be described, and other points will be omitted.

<Description of another ion exchange layer>
In another ion exchange layer 500a, the concentration of the alkali metal having an ionic radius larger than that of sodium is higher than the concentration of the alkali metal having an ionic radius larger than that of sodium in the non-ion exchange layer 100b. In the following, when potassium is used as the alkali metal having an ionic radius larger than that of sodium, another ion exchange layer 500a forming process will be described with reference to FIG.

<Immersion process>
First, as shown to Fig.9 (a), the glass tube 100 for lamps which concerns on the 1st Embodiment of this invention which formed the ion exchange layer 100a is prepared. The glass tube 100 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].

This glass tube 100 is immersed in a bath 502 containing a potassium nitrate (KNO ₃ ) molten salt 501 heated to 350 [° C.] to 450 [° C.], for example, 120 [min] to 240 [min]. The film thickness of another ion exchange layer 500a can be changed according to the time for which the glass tube 100 is immersed in the potassium nitrate molten salt 501. In addition, when it is desired to form an ion exchange layer only on the outer surface layer of the glass tube 100, it is preferable to plug soda glass or quartz glass at both ends of the glass tube 100.

<Washing process>
Next, as shown in FIG. 9B, the excess potassium nitrate molten salt 501 adhering to the surface of the glass tube 500 is washed by washing the glass tube 500 after the ion exchange treatment in a bath 504 containing water 503. Remove.

<Drying process>
Next, as shown in FIG. 9C, the glass tube 500 is dried with a heater 505 or the like, thereby removing water adhering in the cleaning process.

<Image of forming another ion exchange layer>
Then, the image figure of the principal part expanded cross section of the outer surface layer of the glass tube 100 of the immersion process initial stage is shown to Fig.10 (a), The image figure of the principal part enlarged cross section of the outer surface layer of the glass tube 500 of the immersion process last stage is FIG. Each is shown in (b). As shown in FIG. 10A, sodium ions (Na ⁺ ) are distributed on the outer surface layer of the glass tube 500 in the same manner as other portions of the glass tube 100. On the other hand, as shown in FIG. 10 (b), at the end of the dipping process, potassium ions (K ⁺ ) and ions in which some of the sodium ions in the outer surface layer of the glass tube 500 are contained in the molten potassium nitrate salt 501 are used. As a result, more potassium ions are distributed in the outer surface layer of the glass tube 500 than in other portions of the glass tube 500. The ion radius of this potassium ion is larger than the ion radius of a sodium ion. Therefore, in such another ion exchange layer 500a, compressive stress is exerted 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 another ion exchange layer 500a having a compressive stress on the outer surface layer of the glass tube 500 as described above, the glass tube 500 becomes strong against an impact from the outside, and the mechanical properties of the glass tube 500 are increased. Strength can be improved and cracking can be prevented.

<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. 11, a concentrated load is applied to the center of the glass tube supported by the supporting member 506 with a span of 70 [mm] by the indenter 507, 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 3. Table 3 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 3, 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. 12 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 X ₅₀₈ at the center in the tube axis direction to produce a measurement sample 508 having a thickness s of 10 [mm] in the tube axis direction. To do. 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. 13 (a1) to (a4) and (b1) to (b4). 13 (a1) to (a4) show changes in sodium concentration, and FIGS. 13 (b1) to (b4) show changes in potassium concentration. Figure 13 (a1) and (b1) is a glass tube B of the ion exchange untreated, Figure 13 (a2) and (b2) is a glass tube A ₁ subjected to ion exchange treatment with immersion time 120 [min], FIG. 13 (a3) and (b3) show a glass tube A ₂ that has been subjected to ion exchange treatment at an immersion time of 180 [min], and FIGS. 13 (a4) and (b4) show an ion exchange treatment at an immersion time of 240 [min]. Glass tubes A ₃ are shown respectively.

  In FIGS. 13 (a1) to (a4) and (b1) to (b4), the horizontal axis represents the depth [μm] from the outermost surface, and the concentration change of sodium is represented by the 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. 13 (a1) to (a4), in the glass tubes A ₁ , A ₂ , and A ₃ subjected to the ion exchange treatment, the sodium concentration 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 is clear from FIGS. 13 (b1) to (b4), in the glass tubes A ₁ , A ₂ , 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 another ion exchange layer 500a is defined as a region where the potassium content is higher by 1% or more than the potassium content in the non-ion exchange layer 100b, the other ion exchange layer 500a. Is preferably 5 [μm] or more. In the process, the thickness of another ion exchange layer 500a may vary, and in order to sufficiently improve the mechanical strength of the entire glass tube 500 even if the variation is taken into consideration, the thickness is 5 [μm]. It is preferable that there is more. Further, the thickness of another ion exchange layer 500a is more preferably 30 [μm] or more. This is because the mechanical strength of the glass tube 500 is further improved, the outer surface of the glass tube 500 is not easily damaged, and the glass tube 500 is not easily damaged by an external load.

  When another ion exchange layer 500a 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, for the same reason as described above, The thickness of another ion exchange layer 500a 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 500, it is preferable to measure with the following measuring methods. That is, arbitrary 4 [locations] (central portion ₁ to central portion ₄ ) at equal intervals in the central portion in the thickness direction on the cut surface of the measurement sample 508 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 other ion exchange layers 500a are sequentially formed from the surface of the glass tube 500, when both the inner surface layer and the outer surface layer of the glass tube 500 are subjected to ion exchange treatment, the central portion in the thickness direction of the glass tube 500 is used. This is because ion exchange is most difficult to exchange.

  In this experiment, the glass tube 500 shown in Table 1 was used as the composition of the glass tube 500. 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 500 for a lamp according to the fifth embodiment of the present invention, even when used for a low-pressure discharge lamp, the dark start characteristics are not affected by vibrations and shocks associated with transportation and the like. Can be improved. In addition, the glass tube 500 becomes strong against external impact, and the mechanical strength of the glass tube 500 can be improved.

(Sixth embodiment)
FIG. 14A is a cross-sectional view including the tube axis X ₆₀₀ of the low-pressure discharge lamp according to the sixth embodiment of the present invention, FIG. 14B is an enlarged cross-sectional view of the main part of FIG. FIG. 14C shows an enlarged cross-sectional view of the main part of FIG. A low-pressure discharge lamp 600 according to the sixth embodiment of the present invention (hereinafter simply referred to as “lamp 600”) is a cold cathode fluorescent lamp, and the second embodiment of the present invention except for the glass bulb 601. The low-pressure discharge lamp 200 according to FIG.

<Description of glass bulb>
The glass bulb 601 is obtained by processing the glass tube for lamp 500 according to the fifth embodiment of the present invention. The glass bulb 601 has a circular cross section cut perpendicular to the tube axis X ₆₀₀ 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 600 according to the sixth embodiment of the present invention, the dark start-up characteristics of the low-pressure discharge lamp 600 can be improved without being affected by vibrations or shocks associated with transportation or the like. it can. Further, the glass bulb 601 becomes strong against external impact, and the mechanical strength of the glass bulb 601 can be improved.

(Seventh embodiment)
FIG. 15A is a cross-sectional view including a tube axis X ₇₀₀ of a glass tube for a lamp according to a seventh embodiment of the present invention, FIG. 15B is an enlarged cross-sectional view of the main part of FIG. The principal part expanded sectional view of a part is shown in FIG.15 (c), respectively. A lamp glass tube 700 (hereinafter simply referred to as “glass tube 700”) according to a seventh embodiment of the present invention has an ion exchange layer 100a formed on its inner surface layer as shown in FIG. As shown in FIG. 15C, another ion exchange layer 700a is formed on the outer surface layer, and the ion exchange layer 100a, another ion exchange layer 700a, and a non-ion exchange layer in which no ion exchange layer is formed. 100b. Since points other than another ion exchange layer 700a have substantially the same configuration as that described in the fifth embodiment of the present invention, the other ion exchange layer 700a will be described in detail. Other points are omitted.

<Description of another ion exchange layer>
Another ion exchange layer 700a is composed of two layers, a first ion exchange layer 700b and a second ion exchange layer 700c located outside the first ion exchange layer 700b, and has an ion radius that is larger than that of sodium in the first ion exchange layer 700b. The concentration of the alkali metal having a large ion radius is higher than the concentration of the alkali metal having an ionic radius larger than that of sodium in the non-ion exchange layer 100b, and the concentration of the alkali metal in the second ion exchange layer 700c is the alkali metal of the first ion exchange layer 700b. The concentration is lower. Hereinafter, with respect to the case where potassium is used as the alkali metal having an ionic radius larger than that of sodium, another step of forming the ion exchange layer 700a will be described with reference to FIG.

<First immersion process>
First, as shown to Fig.16 (a), the glass tube 100 for lamps which concerns on the 1st Embodiment of this invention which formed the ion exchange layer 100a is prepared. The glass tube 100 has a composition shown in Table 1, for example, 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 100 is immersed in, for example, 120 [min] to 240 [min] in a bath 702 containing a potassium nitrate (KNO ₃ ) molten salt 701 heated to 350 [° C.] to 450 [° C.]. The film thickness of another ion exchange layer 700a can be changed according to the time during which the glass tube 100 is immersed in the potassium nitrate molten salt 701.

<First cleaning step>
Next, as shown in FIG. 16 (b), the excess potassium nitrate molten salt 701 attached to the surface of the glass tube 703 is cleaned by washing the glass tube 703 after the first immersion step in a bath 705 containing water 704. Remove.

<First drying step>
Next, as shown in FIG. 16 (c), the glass tube 703 is dried by a heater 706 or the like, thereby removing moisture adhering in the cleaning process.

<Second immersion process>
Next, as shown in FIG. 16 (d), the glass tube 703 is placed in a bath 708 containing sodium nitrate (NaNO ₃ ) molten salt 707 heated to 350 [° C.] to 450 [° C.], for example, 120 [min]. Immerse for ~ 240 [min]. The film thickness of the second ion exchange layer 700c can be changed according to the time for immersing the glass tube 703 in the sodium nitrate molten salt 707.

<Second cleaning step>
Next, as shown in FIG. 16 (e), the excess sodium nitrate molten salt 707 adhering to the surface of the glass tube 700 is washed by washing the glass tube 700 after the second immersion step in a bath 710 containing water 709. Remove.

<Second drying step>
Next, as shown in FIG. 16 (f), the glass tube 700 is dried by a heater 711 or the like, thereby removing water adhering in the cleaning process.

  In the present embodiment, the step of forming another ion exchange layer 700a after forming the ion exchange layer 100a has been described. However, even if the ion exchange layer 100a is formed after forming another ion exchange layer 700a. Good. Further, the ion exchange layer 100a may be formed while the first ion exchange layer 700b and the second ion exchange layer 700c of another ion exchange layer 700a are formed.

<Image of forming another ion exchange layer>
Next, a process in which another ion exchange layer 700a is formed on the outer surface layer of the glass tube 100 will be described. FIG. 17A is an image view of an enlarged cross section of the main part of the outer surface layer of the glass tube 100 in the initial stage of the first immersion process, and FIG. FIG. 17C is an image diagram of an enlarged cross-sectional view of the main part of the outer surface layer of the glass tube 700 at the end of the second immersing process. As shown in FIG. 17A, sodium ions (Na ⁺ ) are distributed on the outer surface layer of the glass tube 100 in the same manner as other portions of the glass tube 100. On the other hand, as shown in FIG. 17B, 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 703, a first ion exchange layer 700b in which more potassium ions are distributed than in other portions of the glass tube 703 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 700b, compressive stress is exerted when potassium ions having a larger ion radius than the sodium ions are accommodated in a portion where sodium ions having a smaller ion radius are accommodated. By forming the first ion exchange layer 700b acting on the compressive stress on the outer surface layer of the glass tube 703 in this way, the glass tube 703 becomes strong against impact from the outside, and the mechanical strength of the glass tube 703 is increased. Strength can be improved. Next, as shown in FIG. 17C, at the end of the second immersion step, potassium ions in the outer surface layer of the first ion exchange layer 700b are replaced with sodium ions, and the second ion exchange layer 700c is formed. The Thereby, the compressive stress acting on the second ion exchange layer 700c is smaller than that of the first ion exchange layer 700b, and the second ion exchange layer 700c is likely to be damaged. As described above, the ion exchange layer 700a is composed of the first ion exchange layer 700b in which a large compressive stress is applied and the second ion exchange layer 700c in which a small compressive stress is applied on the outer side thereof. Even if the outer surface of the glass tube 700 is finely scratched, it is possible to prevent cracks due to the scratch.

  Here, the first ion exchange layer 700b 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 700c is defined as In order to improve the mechanical strength of the glass tube 700 when it is defined that the potassium content is lower than the potassium content of the first ion exchange layer 700b outside the first ion exchange layer, The one ion exchange layer 700b is preferably 10 [μm] or more. Furthermore, the first ion exchange layer 700b is more preferably 20 [μm] or more. In this case, the mechanical strength of the glass tube 700 is further improved, and the glass tube 700 is hardly damaged by an external load.

  The second ion exchange layer 700c is more preferably 10 [μm] or more. In this case, even if the surface of the glass tube 700 is scratched, the scratch is less likely to reach the inside than the second ion exchange layer 700c. Furthermore, the second ion exchange layer 700c 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 700c, and it is possible to prevent cracks due to the flaw. It is.

  The total thickness of the first ion exchange layer 700b and the second ion exchange layer 700c is preferably 20 [μm] or more. When the total thickness of the first ion exchange layer 700b and the second ion exchange layer 700c is less than 20 [μm], the second ion exchange layer 700c is formed outside the first ion exchange layer 700b after the first ion exchange layer 700b is formed. This is because it is difficult.

  Moreover, it is preferable that the thickness of the 1st ion exchange layer 700b is thicker than the thickness of the 2nd ion exchange layer 700c. In this case, the mechanical strength of the glass tube 700 can be improved, and even if the outer surface of the glass tube 700 is slightly damaged, it is possible to prevent cracks due to the scratch.

  Furthermore, the thickness of the first ion exchange layer 700b is preferably 5 [μm] or more thicker than the thickness of the second ion exchange layer 700c. In this case, even if the outer surface of the glass tube 700 has more scratches, the progress of the scratches can be suppressed by the first ion exchange layer 700b, 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 glass tube for a lamp 700 according to the seventh embodiment of the present invention, even when used for a low-pressure discharge lamp, the dark start characteristic is not affected by vibrations and shocks associated with transportation and the like. Can be improved. Further, even if the outer surface of the lamp glass tube 700 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 700 can be prevented by visually checking and replacing the scratches on the outer surface of the glass tube 700 before that. Can do.

(Eighth embodiment)
FIG. 18A is a cross-sectional view including the tube axis of a low-pressure discharge lamp according to the eighth embodiment of the present invention, FIG. 18B is an enlarged cross-sectional view of the main part of FIG. 18B, and FIG. FIG. 18C shows an enlarged sectional view of the part. A low-pressure discharge lamp 800 (hereinafter simply referred to as “lamp 800”) according to the eighth embodiment of the present invention is a cold cathode fluorescent lamp, and the second embodiment of the present invention is described except for the glass bulb 801. The low-pressure discharge lamp 200 according to the embodiment has substantially the same configuration. Therefore, the glass bulb will be described in detail, and the other points will be omitted.

<Description of glass bulb>
A glass bulb 801 is obtained by processing a lamp glass tube 700 according to a seventh embodiment of the present invention, and has a circular cross section cut perpendicular to the tube axis X ₈₀₀ 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 800 according to the eighth embodiment of the present invention, the dark starting characteristics of the low-pressure discharge lamp 800 are improved without the cesium compound falling off due to vibrations or impacts associated with transportation or the like. can do. Even if the outer surface of the glass bulb 801 has some scratches, cracks due to the scratches can be prevented. However, if the scratches increase or deepen, cracks may occur. However, if the scratches on the outer surface of the glass bulb 801 are visually confirmed before the lamp 800 is replaced, the cracks in the glass bulb 801 are obviated. Can be prevented.

(Ninth embodiment)
FIG. 19 is an exploded perspective view of a backlight unit 900 according to the ninth embodiment of the present invention. The backlight unit 900 according to the ninth embodiment of the present invention is a direct type, and includes a rectangular parallelepiped housing 901 having one surface opened, and a plurality of lamps 200 housed in the housing 901. A pair of sockets 902 for electrically connecting the lamp 200 to a lighting circuit (not shown) and an optical sheet 903 covering the opening of the housing 901 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 901 is made of, for example, polyethylene terephthalate (PET) resin, and a reflective surface 904 is formed by depositing a metal such as silver on the inner surface thereof. Note that the housing 901 may be made of a material other than resin, for example, a metal material such as aluminum or a cold-rolled material (for example, SPCC). In addition to the metal vapor-deposited film, the reflective surface 904 on the inner surface is, for example, a material obtained by attaching a reflective sheet with increased reflectance by adding calcium carbonate, titanium dioxide, or the like to polyethylene terephthalate (PET) resin. May be.

  Inside the housing 901, a socket 902, an insulator 905, and a cover 906 are disposed. Specifically, the sockets 902 are provided at predetermined intervals in the lateral direction (longitudinal direction) of the housing 901 corresponding to the arrangement of the lamps 200. The socket 902 is obtained by processing a plate material made of stainless steel or phosphor bronze, for example, and has a fitting portion 902a into which the lead wire 203 is fitted. Then, the lead wire 203 is fitted by being elastically deformed so as to expand the fitting portion 902a. As a result, the lead wire 203 fitted in the fitting part 902a is pressed by the restoring force of the fitting part 902a and is difficult to come off. Thereby, the lead wire 203 can be easily fitted into the fitting portion 902a, but can be made difficult to come off.

  The socket 902 is covered with an insulator 905 so as not to short-circuit between adjacent sockets 902. The insulator 905 is made of, for example, polyethylene terephthalate (PET) resin. Note that the insulator 905 is not limited to the above structure. Since the socket 902 is in the vicinity of the internal electrode 202 that becomes relatively high during operation of the lamp 200, the insulator 905 is preferably made of a heat-resistant material. As a material of the heat-resistant insulator 905, for example, polycarbonate (PC) resin, silicon rubber, or the like can be used.

  Inside the housing 901, 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 901 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 906 divides the socket 902 and the space inside the housing 901, and is made of, for example, polycarbonate (PC) resin. The cover 906 keeps the periphery of the socket 902 warm and at least highly reflects the surface on the housing 901 side. By reducing the brightness, a decrease in luminance at the end of the lamp 200 is reduced.

  The opening of the housing 901 is covered with a light-transmitting optical sheet 903 and is sealed so that foreign matters such as dust and dust do not enter inside. The optical sheet 903 is formed by laminating a diffusion plate 907, a diffusion sheet 908, and a lens sheet 909.

  The diffusion plate 907 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 901. The diffusion sheet 908 is made of, for example, a polyester resin. The lens sheet 909 is, for example, a laminate of an acrylic resin and a polyester resin. These optical sheets 903 are arranged so as to be sequentially superimposed on the diffusion plate 907.

<Summary>
As described above, according to the configuration of the backlight unit 900 according to the ninth embodiment of the present invention, it is possible to improve the dark starting characteristics of the low-pressure discharge lamp 200 without being affected by vibrations and shocks associated with transportation and the like. The backlight unit 900 can be started up early.

(Tenth embodiment)
FIG. 20 is a partially cutaway perspective view of a backlight unit according to the tenth embodiment of the present invention. The backlight unit 1000 according to the tenth embodiment of the present invention is an edge light type and includes a reflector 1001, a lamp 200, a socket (not shown), a light guide plate 1002, a diffusion sheet 1003, and a prism sheet 1004. Yes.

  The reflection plate 1001 is disposed so as to surround the periphery of the light guide plate 1002 except for the liquid crystal panel side (arrow Q), and the side surface covering the bottom surface portion 1001b covering the bottom surface and the side surface excluding the side where the lamp 200 is disposed. Part 1001a and a curved lamp side surface part 1001c covering the periphery of the lamp 200, and the light emitted from the lamp 200 is reflected from the light guide plate 1002 to the liquid crystal panel (not shown) side (arrow Q). Let Moreover, the reflecting plate 1001 is made of, for example, a film-like PET deposited with silver or a laminated metal foil such as aluminum.

  The socket has substantially the same configuration as the socket 902 used in the backlight unit 900 according to the ninth embodiment of the present invention. In FIG. 20, the end of the lamp 200 is omitted for convenience of illustration.

  The light guide plate 1002 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 1001 provided on the bottom surface of the backlight unit 1000. Has been. As a material, polycarbonate (PC) resin or cycloolefin-based resin (COP) can be applied.

  The diffusion sheet 1003 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 1002.

  The prism sheet 1004 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 1003. Note that a diffusion plate may be further stacked on the prism sheet 1004.

  In the case of this embodiment, a reflective sheet (not shown) is provided on the outer surface of the glass bulb 201 except for a part in the circumferential direction of the lamp 200 (the light guide plate 1002 side when inserted into the backlight unit 1000). Aperture type lamps may also be used.

<Summary>
As described above, according to the configuration of the backlight unit 1000 according to the tenth embodiment of the present invention, it is possible to improve the dark starting characteristics of the low-pressure discharge lamp 200 without being affected by vibrations and shocks associated with transportation and the like. The backlight unit 1000 can be started up early.

(Eleventh embodiment)
FIG. 21 shows an outline of a liquid crystal display device according to the eleventh embodiment of the present invention. As shown in FIG. 21, a liquid crystal display device 1100 is, for example, a 32 inch liquid crystal television, a liquid crystal screen unit 1101 including a liquid crystal panel and the like, a backlight unit 900 and a lighting circuit according to the ninth embodiment of the present invention. 1102.

  The liquid crystal screen unit 1101 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 1102 lights the lamp 200 inside the backlight unit 900. The lamp 200 is operated at, for example, a lighting frequency of 40 [kHz] to 100 [kHz] and a lamp current of 3.0 [mA] to 25 [mA].

  FIG. 21 illustrates the case where the low-pressure discharge lamp 200 according to the first embodiment is inserted into the backlight unit 900 according to the ninth embodiment of the present invention as the light source device of the liquid crystal display device 1100. The low pressure discharge lamp 300 according to the third embodiment of the present invention, the low pressure discharge lamp 400 according to the fourth embodiment of the present invention, the low pressure discharge lamp 600 according to the sixth embodiment of the present invention, and the present invention. A low-pressure discharge lamp 800 according to the eighth embodiment of the invention can also be used. Further, the backlight unit 1000 according to the tenth 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 1100 according to the tenth embodiment of the present invention, the dark start-up characteristics of the low-pressure discharge lamp 200 can be improved without being affected by vibrations or shocks associated with transportation or the like. In addition, the liquid crystal display device 1100 can be started up at an early stage.

<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 material (1) About ultraviolet absorption Absorbing ultraviolet rays of 254 [nm] and 313 [nm] by doping a glass, which is a material for a glass tube for a lamp, with a transition metal oxide in a predetermined amount. Can do. 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 and glass bulb is not limited to a straight tube shape, for example, L-shape, U-shape, U-shape It may be a 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) 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 light 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)
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 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 = 0,056).

  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 the NTSC triangle (NTSC triangle) connecting the chromaticity coordinate values of the three primary colors of the NTSC standard in the CIE1931 chromaticity diagram. This is performed by the ratio of the area of the triangle that can connect the 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 low-pressure discharge lamp according to each of the above embodiments, the one having a phosphor layer on the inner surface of the glass bulb has been described. 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) Conceptual diagram in the main part enlarged cross section of the inner surface layer of the glass tube for lamps in the initial stage of the immersion process, (b) Conceptual diagram in the main part enlarged cross section of the inner surface layer of the glass tube for lamps in the final stage of the immersion process. (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.4 (a). (A) Sectional drawing including the tube axis of the low-pressure discharge lamp concerning the 3rd Embodiment of this invention, (b) The principal part expanded sectional view of C part of Fig.5 (a). Sectional drawing including the tube axis | shaft of the modification of the low pressure discharge lamp which concerns on the 3rd Embodiment of this invention. (A) Sectional drawing including the tube axis | shaft of the low pressure discharge lamp which concerns on the 4th Embodiment of this invention, (b) The principal part expanded sectional view of D part of Fig.7 (a). (A) Sectional drawing including the tube axis of the glass tube for lamp | ramp which concerns on the 5th Embodiment of this invention, (b) The principal part expanded sectional view of E part of Fig.8 (a), (c) FIG.8 (a) ) F main part enlarged sectional view of F part (A) The conceptual diagram of the immersion process of another ion exchange layer formation process of the glass tube for lamps, (b) The conceptual diagram of a washing process similarly, (c) The conceptual diagram of a drying process (A) Conceptual 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 immersion process, (b) Conceptual 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 immersion process. Conceptual diagram showing destructive test conditions The figure which shows the measuring method of the concentration of potassium of the ion exchange layer (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 . (A) Cross-sectional view including the tube axis of the low-pressure discharge lamp according to the sixth embodiment of the present invention, (b) an enlarged cross-sectional view of the main part of the G portion in FIG. 14 (a), (c) FIG. The H part of the main part enlarged sectional view of (A) Sectional drawing including the tube axis | shaft of the glass tube for lamps concerning the 7th Embodiment of this invention, (b) The principal part expanded sectional view of the I section of Fig.15 (a), (c) Fig.15 (a) ) Enlarged sectional view of the main part of J (A) The conceptual diagram of the 1st immersion process of another ion exchange layer formation process of the glass tube for lamps, (b) The conceptual diagram of the 1st washing process similarly, (c) The conceptual diagram of the 1st drying process similarly, (d ) Similarly conceptual diagram of the second immersion step, (e) Similarly conceptual diagram of the second cleaning step, (f) Similarly conceptual diagram of the second drying step (A) The conceptual diagram in the principal part expanded cross section of the outer surface layer of the glass tube for lamps of the 1st immersion process initial stage, (b) The concept in the principal part expanded cross section of the outer surface layer of the glass tube for lamps of the 1st immersion process final stage. Figure, (c) Conceptual diagram in an enlarged cross-section of the main part of the outer surface layer of the glass tube for lamp at the end of the second immersion step (A) Cross-sectional view including the tube axis of the low-pressure discharge lamp according to the eighth embodiment of the present invention, (b) an enlarged cross-sectional view of the main part of the K portion in FIG. 18 (a), (c) FIG. The principal part expanded sectional view of L part of The disassembled perspective view of the backlight unit which concerns on the 9th Embodiment of this invention. The partially cutaway perspective view of the backlight unit according to the tenth embodiment of the present invention. Schematic perspective view of a liquid crystal display device according to an eleventh embodiment of the present invention (A) Sectional view including the tube axis of a conventional low pressure discharge lamp when the cesium compound is deposited on the electrode surface, (b) Conventional when the cesium compound is deposited on the inner surface of the end of the glass bulb Sectional view including tube axis of low-pressure discharge lamp

Explanation of symbols

100,500 Glass tube for lamp 100a Ion exchange layer 200,300,400,600,800 Low pressure discharge lamp 201,401,601,801 Glass bulb 900,1000 Backlight unit 1100 Liquid crystal display device

Claims (10)

A glass tube in which an ion exchange layer is formed on an inner surface layer, wherein the concentration of an alkali metal having an ion radius larger than that of sodium in the ion exchange layer is an alkali metal having an ion radius larger than that of sodium in a non-ion exchange layer A glass tube for a lamp characterized by having a higher concentration than the above. The glass tube for a lamp according to claim 1, wherein the alkali metal is cesium or potassium. The glass tube for a lamp according to claim 1 or 2, wherein the ion exchange layer has a thickness of 5 µm or more. The outer surface layer is formed with another ion exchange layer in which the concentration of alkali metal having a larger ion radius than sodium is higher than the concentration of alkali metal having a larger ion radius than sodium in the non-ion exchange layer. The glass tube for a lamp according to any one of claims 1 to 3. 5. The glass tube for a lamp according to claim 1, 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 5, 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 6, which is in a range of not less than mol%] and not more than 12 [mol%]. A low-pressure discharge lamp comprising the glass tube for a lamp according to any one of claims 1 to 7 as a glass bulb. A backlight unit comprising the low-pressure discharge lamp according to claim 8. A liquid crystal display device comprising the backlight unit according to claim 9.

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