JP4900123B2 - External electrode type rare gas fluorescent lamp - Google Patents

Description

  The present invention relates to an external electrode type rare gas fluorescent lamp used for general illumination and a backlight for liquid crystal.

  In recent years, as disclosed in Patent Document 1, only a rare gas is enclosed in a straight tubular glass bulb, and an electrode disposed over the entire length of the glass bulb made of a pair of conductive materials on the outer surface of the glass bulb. The external electrode type rare gas fluorescent lamp provided is used as an OA document reading light source for scanners, copying machines, facsimiles and the like.

  This external electrode type rare gas fluorescent lamp does not have an electrode inside the glass bulb, so there are few failures due to electrode deterioration, the lamp has a long life, and mercury is not used as a luminescent species, and only rare gas is used. This is because the light rises and stabilizes at the start of lighting even under low temperature conditions, and is suitable for that purpose.

  By the way, fluorescent lamps using mercury emission have been conventionally used for liquid crystal backlights and signboard illumination.

  Recently, in household products such as liquid crystal televisions and personal computers, the use of mercury as a luminescent species has started to be regarded as an environmental problem. On the other hand, external electrode type rare gas fluorescent lamps have attracted attention as pollution-free light sources because they do not use mercury as the luminescent species.

  FIG. 6 shows an external electrode type rare gas fluorescent lamp 100 as a light source for reading OA originals. 6A is a perspective view of the entire rare gas fluorescent lamp, and FIG. 6B is a cross-sectional view perpendicular to the tube axis of the rare gas fluorescent lamp. The phosphor layer 130 on the inner surface of the glass bulb 110 is removed by a predetermined width in one direction along the axial direction of the glass bulb to form an aperture portion 115, and light from the inside of the glass bulb is emitted in one limited direction. It has a structure. The total length of the glass bulb is about 36 cm in accordance with the document width. The light extraction direction is determined, and the electrodes 120 and 120 'are generally formed of a relatively wide aluminum (Al) metal electrode having a width of, for example, 8 mm on the outer surface of the glass bulb. Is. Reference numeral 40 denotes a power supply terminal.

  When this external electrode type rare gas fluorescent lamp 100 is used for a backlight of a liquid crystal or a backlight of a signboard, as a backlight of a 50-inch liquid crystal screen, for example, due to recent progress in enlargement of the liquid crystal size, The total length of the lamp needs to exceed 1 m, for example.

  In liquid crystal backlight applications, unlike OA, light extraction is required from the entire circumference of the glass bulb of the fluorescent lamp. Therefore, the glass bulb does not have an aperture portion, and the electrode also becomes a member that shields light, so that it is required to be as thin as possible, for example, 0.5 mm wide.

Then, although it is 0.5 mm wide, it is extremely technically difficult to attach an Al electrode having a length of 1 m to a glass bulb having a length of more than 1 m, and the production efficiency is extremely poor. Therefore, it is conceivable to use a conductive printed electrode as the electrode. As a versatile printed electrode, there is a conductive silver paste.
JP 2001-135277 A

  In the external electrode type rare gas fluorescent lamp, power is supplied from a power supply unit provided in the electrode end region. Since the lamp of the same type applies a high voltage between the external electrodes, as shown in FIG. 7, the electrode part of the light emitting part excluding the power feeding part is covered with an insulating coating film 60 for safety. For example, as shown in FIG. 7, the power feeding terminal 40 is covered with a holder 50 made of an insulating resin. Reference numeral 45 denotes a power supply line.

  In the OA application, the lamp only lights up for each reading operation of the copying machine, for example, and the service life is about 1000 hours even when converted to continuous lighting.

  However, a long lamp life of tens of thousands of hours is required for a backlight application of a liquid crystal, for example, a backlight of a liquid crystal TV.

  Therefore, when an external electrode type rare gas fluorescent lamp equipped with an electrode of conductive silver paste was used for more than 4,000 hours in an environment of high temperature and high humidity (85 ° C, 95%), the electrode power supply in the holder was mainly used. The peripheral edge of the portion oozes out so that the tongue extends in the circumferential direction of the glass bulb, and the distance between the separated electrodes is substantially close at the position of the power feeding portion. Then, if left as it is, there is a risk of causing a serious failure such as creeping discharge between the electrodes or short-circuiting. Upon earnest investigation, it was found that ion migration of silver, which is the main component of the conductive silver paste, occurred.

  With ion migration, the metal used for the wiring and electrodes is applied to the conductor metal with moisture attached, repeatedly melting, moving, and precipitating, moving on an insulator such as glass, This is a phenomenon where the circuit is short-circuited.

  Accordingly, an object of the present invention is an external electrode type rare gas fluorescent lamp in which an electrode is printed with a conductive silver paste, and an external device having a configuration that suppresses the growth of silver ion migration that occurs in a power feeding portion of an exposed electrode. It is an object to provide an electrode type rare gas fluorescent lamp.

  In order to solve the above problem, the invention according to claim 1 is characterized in that a predetermined amount of rare gas is sealed inside a glass bulb having an inner surface coated with a fluorescent material, and extends in the bulb axial direction on the outer surface of the glass bulb. In the external electrode type rare gas fluorescent lamp in which a pair of electrodes formed by firing a conductive silver paste is disposed, the pair of electrodes is separated from the firing temperature of the conductive silver paste, except for the feeding portion at each end. At least 1 made of a material having a melting point lower than the firing temperature of the conductive silver paste on the outer surface of the glass bulb between the power feeding portions of each electrode. The external electrode type rare gas fluorescent lamp is formed with two strips.

  According to the second aspect of the present invention, a predetermined amount of a rare gas is sealed inside a glass bulb having an inner surface coated with a fluorescent material, and a pair of conductive silver paste is fired that extends in the bulb axis direction on the outer surface of the glass bulb. In the external electrode type rare gas fluorescent lamp in which the electrodes are arranged, the pair of electrodes is covered with a coating layer made of a material having a melting point lower than the firing temperature of the conductive silver paste, including the periphery of the pair of electrodes. The coating layer is an external electrode type rare gas fluorescent lamp characterized by comprising an opening for exposing a power feeding portion located inside each end portion of each electrode.

  In the present invention, the power feeding part is a part of an electrode extending in the bulb axis direction on the outer surface of the glass bulb and is a portion exposed from a coating layer made of a material having a melting point lower than the firing temperature of the conductive silver paste. That means.

  According to the present invention, the coating layer made of a material having a melting point lower than the firing temperature of the conductive silver paste is provided on the electrode portion, and the belt-like portions are provided on both sides in the valve circumferential direction of the power feeding portion, thereby Migration can be completely prevented, and even if silver ion migration occurs in the exposed power supply section, the extension of the ion migration is blocked by the band-shaped section, and creeping discharge occurs on the outer surface of the bulb between the electrodes, or a short circuit occurs. Therefore, it is possible to provide a safe external electrode type rare gas fluorescent lamp that does not cause a serious failure.

  In addition, in the case of having a coating layer having an opening that exposes the power feeding portion of the electrode, even if silver ion migration occurs in the exposed power feeding portion, the extension of ion migration is blocked by the coating layer that is the periphery of the opening. Thus, it is possible to provide a safe external electrode type rare gas fluorescent lamp that does not cause a serious failure such as creeping discharge or short-circuiting on the outer surface of the bulb between the electrodes. In particular, since the band-shaped part is made of a material having a melting point lower than the firing temperature of the conductive silver paste, the coating has sufficient adhesion to the glass bulb without increasing the temperature to the firing temperature of the conductive silver paste. Layers and strips can be used. In addition, since the coating layer is made of a material having a melting point lower than the firing temperature of the conductive silver paste, the shape of the conductive silver paste as an electrode is not changed, and intrusion of moisture in the atmosphere can be prevented. .

  FIG. 1 is a perspective view showing an overall view of an external electrode type rare gas fluorescent lamp 1 as a first embodiment of the present invention. FIG. 2 shows a cross-sectional view perpendicular to the tube axis direction taken along the plane including the power feeding portion. The members unnecessary for the description of the invention, such as plate-like power supply terminals to be attached later to the power supply unit, power supply lines, heat shrinkable tubes that cover the power supply terminals and are reinforced and fixed, are not shown. A fluorescent material is applied to the entire inner surface, a predetermined amount of rare gas is sealed inside the glass bulb 10 on which the phosphor layer 13 is formed, and a pair of conductive silver paste is fired along the bulb axis direction on the outer surface of the glass bulb. The electrodes 2 and 2 are arranged. In FIG. 1 and FIGS. 3, 4, and 5, which will be described later, of the pair of electrodes 2, 2, the electrode located on the back side of the drawing is omitted, but in FIG. 2 shows power feeding portions 2a and 2a 'at the end of the two.

  The conductive silver paste for the electrode is applied to the glass bulb 10 by screen printing, and then baked at about 500 ° C. Each of the pair of electrodes 2 and 2 is covered with a translucent coating layer 11 made of a material having a melting point lower than the firing temperature of the conductive silver paste, except for the power feeding portions 2a and 2a 'at the respective ends. ing.

  A strip 12 made of a material having a melting point lower than the firing temperature of the conductive silver paste is exposed from the coating layer 11 on the outer surface of the glass bulb 10 between the power feeding portions 2a and 2a 'of the electrodes 2 and 2. The feeding portions 2a and 2a 'are formed with a length that is equal to or longer than the length of the lamp bulb in the axial direction.

Although the belt-like portion 12 is shown integrally with the coating layer 11 in FIG. 1, it may be formed separately from the coating layer 11. Moreover, the strip | belt-shaped part 12 is the glass bulb | bulb circumferential direction of electric power feeding part 2a, 2a 'of each electrode 2, 2, Comprising: On the glass bulb outer surface between electric power feeding part 2a, 2a' of each electrode 2, 2 A plurality of lines may be formed.
Note that the belt-like portion is not limited to a linear peripheral edge, and may be, for example, a wave shape or a sawtooth shape.

  FIG. 3 shows an overall view of an external electrode type rare gas fluorescent lamp 1 as a second embodiment of the present invention. Each of the pair of electrodes 2 and 2 is covered with a coating layer 11 made of a material having a melting point lower than the firing temperature of the conductive silver paste, including the periphery thereof, and the coating layer 11 is formed from the respective end portions of each electrode. An opening 11a that exposes the power feeding portions 2a and 2a 'located inside is provided, and power is fed from the opening 11a. In this embodiment, only the portions of the power feeding units 2a and 2a ′ are opened.

In the embodiment of FIG. 1, to give specific materials and numerical values, the glass bulb 10 is soft glass, its total length is 1250 mm, a rare gas consisting of xenon is enclosed in the bulb, and the enclosed gas pressure is 16 kPa to For example, it is 21.6 Pa. For example, the phosphor layer is made of (R; (Y, Gd) BO ₃ : Eu, G; LaPO 4: Ce, Tb, B; BaMgAl ₁₄ O ₂₃ : Eu), and its thickness is 12 μm to 17 μm. An example is 15 μm.

The electrode material is a conductive silver paste and is applied onto the glass bulb by screen printing. The firing temperature of the conductive silver paste is between 480 and 500 ° C. In the present invention, firing was performed at 500 ° C. Low melting point glass is suitable as a material having a melting point lower than the firing temperature of the conductive silver paste constituting the electrode and constituting the belt-like part and the coating layer, for example, bismuth-based lead-free containing bismuth (Bi) For example, glass is made of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , ZnO, Bi ₂ O ₃ , and BaO.

The bismuth-based lead-free glass has a thermal expansion coefficient in the temperature range of 50 to 350 ° C., which is 9.7 × 10 ⁻⁶ / K, for example, which is 9.7 × 10 Since the bismuth-based lead-free glass is close to 10 ⁻⁶ / K, the softening point is 40 degrees lower than that of the soft glass used for the glass bulb material in the fluorescent lamp, so that the adhesion between the glasses is strong. That glass used in the glass bulb material is often a lead-free glass, the thermal expansion coefficient of the lead-free bismuth glass is 8.4 × ^{10 -6} /K~×10.4×10 -6 / K preferable.

  FIG. 4 shows a state in which a conductive epoxy adhesive 5 for attaching a power supply terminal made of, for example, copper (Cu) is applied to the power supply units 2a and 2a ′. The firing temperature at which the conductive epoxy adhesive 5 solidifies is 100 to 150 ° C.

  FIG. 5 shows a state where the power supply terminals 6 and 6 ′ are pasted and fixed via the conductive epoxy adhesive 5 applied to the power supply unit. In actual use, although not shown, a power supply line is connected to the power supply terminals 6 and 6 ', and the power supply portion is covered with a heat-shrinkable resin tube and pressed and reinforced by pressing on the glass bulb side.

And the electric power feeding part side of a lamp | ramp is accommodated in the holder which consists of insulating resin.
The effect of the present invention was verified with the lamp of the embodiment of the form shown in FIG. Specific lighting conditions are a lamp voltage of 3.5 kVp-p, a lamp current of 10 mA, and a lighting frequency of 50 kHz. As a result, the tip of the silver ion migration reached the strip 12 from the end of the electrode after 2,000 hours had elapsed. However, it was confirmed that there was no progress in ion migration of silver after 60,000 hours.

  That is, according to the present invention, the coating layer made of a material having a melting point lower than the firing temperature of the conductive silver paste constituting the electrode and the belt-like portion are provided on both sides of the electrode portion and the feeding portion in the valve circumferential direction, respectively. Therefore, even if silver ion migration occurs in the exposed power feeding part, the extension of ion migration is suppressed, and there is no risk of causing a serious failure such as creeping discharge between the electrodes or short-circuiting. An external electrode type rare gas fluorescent lamp can be obtained.

The fluorescent lamp to which the present invention is applied may have a glass bulb provided with an aperture portion that partially intensifies light. In such a fluorescent lamp, the covering layer covering the electrode is low. A glass having a melting point glass mixed with alumina (Al ₂ O ₃ ), titania (TiO ₂ ) or the like as a reflective material may be used.

1 shows an overall view of an external electrode type rare gas fluorescent lamp as a first embodiment of the present invention. FIG. Sectional drawing perpendicular | vertical to a pipe-axis direction including a feed part is shown. An overall view of an external electrode type rare gas fluorescent lamp as a second embodiment of the present invention is shown. The state which apply | coated the conductive silver paste in order to attach a power feeding plate to a power feeding part is shown. The state which stuck and fixed the power supply board through the conductive epoxy adhesive apply | coated to the power supply part is shown. An overall view of a conventional external electrode type rare gas fluorescent lamp as a light source for reading OA originals is shown. The state which equipped the holder at the edge part of the conventional external electrode type | mold rare gas fluorescent lamp is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 External electrode type rare gas fluorescent lamp 2 Electrode 2a, 2a 'Feed part 5 Conductive epoxy adhesive 6, 6' Feed terminal 10 Glass bulb 11 Cover layer 11a Opening part 12 Strip | belt-shaped part 13 Phosphor layer 100 External electrode rare gas fluorescence lamp
DESCRIPTION OF SYMBOLS 110 Glass bulb 115 Aperture part 120, 120 'Electrode 130 Phosphor layer 40 Feeding terminal 45 Feeding line 50 Holder 60 Resin coating film

Claims (2)

A predetermined amount of rare gas is sealed inside a glass bulb with a fluorescent material on the inner surface,
In the external electrode type rare gas fluorescent lamp provided with a pair of electrodes formed by firing a conductive silver paste extending in the bulb axial direction of the outer surface of the glass bulb,
The pair of electrodes is coated with a coating layer made of a material having a melting point lower than the firing temperature of the conductive silver paste, except for the feeding portion at each end,
External electrode type noble gas characterized in that at least one band-shaped portion made of a material having a melting point lower than the firing temperature of the conductive silver paste is formed on the outer surface of the glass bulb between the feeding portions of each electrode. Fluorescent lamp. A predetermined amount of rare gas is sealed inside a glass bulb with a fluorescent material coated on the inner surface.
In the external electrode type rare gas fluorescent lamp provided with a pair of electrodes formed by firing a conductive silver paste extending in the bulb axial direction of the glass bulb outer surface,
The pair of electrodes is covered with a coating layer made of a material having a melting point lower than the firing temperature of the conductive silver paste, including the periphery thereof, and the coating layer is located on the inner side of each end of each electrode. An external electrode type rare gas fluorescent lamp comprising an opening for exposing a power feeding unit.

Images