JP2007035585A - External electrode type fluorescent lamp and back light unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an external electrode type fluorescent lamp with good dark starting characteristics, and also to provide a back light unit at low cost. <P>SOLUTION: This external electrode type fluorescent lamp 1 is provided with: a tubular glass bulb 2; a pair of external electrodes 3a, 3b arranged on both end side outer periphery surface of the glass bulb 2; and a phosphor layer 5 formed in an inner surface of the glass bulb 2. The phosphor layer 5 contains phosphor particles having electron emission atoms. At least an end-edge side of the phosphor layer 5 closer to one end of the glass bulb end approach is extended from an end edge equivalent position B on a tube central part side of the external electrode 3a to a position entering 1-7 mm to the tube end part side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an external electrode type fluorescent lamp including external electrodes at both ends of an outer peripheral surface of a tubular glass bulb, and a backlight unit including the same.

As with the cold cathode fluorescent lamp, the external electrode fluorescent lamp is suitable for reducing the diameter as compared with the hot cathode fluorescent lamp. For this reason, the external electrode type fluorescent lamp is suitably used as a light source of a backlight unit of a liquid crystal television, for example, which is required to be thin (downsized).
In the external electrode fluorescent lamp, external electrodes are disposed at both ends of the outer peripheral surface of a tubular glass bulb, and a phosphor layer is formed on the inner surface of the glass bulb. The external electrode fluorescent lamp emits ultraviolet rays by exciting mercury enclosed in the glass bulb by discharge and emitting light by converting the ultraviolet rays into visible rays by the phosphor layer.

Here, when the phosphor layer is present in the region corresponding to the external electrode on the inner peripheral surface of the glass bulb, mercury is adsorbed to the phosphor during discharge, so-called mercury consumption is generated in which the amount of mercury contributing to light emission is reduced, This is known to reduce lamp life.
Therefore, Patent Document 1 proposes not to form a phosphor layer in a region corresponding to an external electrode in a glass bulb. Thereby, the above-mentioned mercury consumption can be suppressed.
JP 2004-22209 A

However, the external electrode type fluorescent lamp as described above has a problem in the dark start characteristic such that in the dark state, the discharge is delayed and it takes time to start the start, and the lighting is delayed even if a voltage is applied.
In order to improve the dark start characteristics, it is conceivable to arrange the electron-emitting substance in the vicinity of the electrode, but there is a problem that the material cost and the manufacturing cost increase.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an external electrode fluorescent lamp and a backlight unit which are low in cost and have improved dark starting characteristics.

  Therefore, an external electrode fluorescent lamp according to the present invention includes a tubular glass bulb, a pair of external electrodes disposed on the outer peripheral surfaces at both ends of the glass bulb, and a phosphor formed on the inner surface of the glass bulb. An external electrode type fluorescent lamp, wherein the phosphor layer includes phosphor particles having electron-radiating atoms, and at least a phosphor layer end side near one end of the glass bulb is a tube of the external electrode It is characterized in that it extends from a position corresponding to the edge on the center side to a position where it enters from 1 mm to 7 mm toward the tube end.

As a result of intensive research by the present inventors, when a phosphor layer is present in a region corresponding to the external electrode in the glass bulb, a starting voltage is applied to the external electrode to generate an electric field, thereby generating electron-emitting atoms in the phosphor layer. It has been found that more electrons are emitted and a discharge is induced by the emitted electrons to improve the starting characteristics under dark conditions.
In the above configuration, since the phosphor layer is formed in a region corresponding to the external electrode within the glass bulb from a position where it enters 1 mm or more from the edge of the external electrode, the dark start-up characteristics can be improved. In addition, since the amount entering the region corresponding to the external electrode is 7 mm or less, it was confirmed by experiments that the above-described reduction in lamp life due to mercury consumption can be suppressed.

Furthermore, since it is possible to improve the dark start characteristics only by adjusting the relative position between the phosphor layer and the external electrode in the manufacturing process, an external electrode fluorescent lamp having improved dark start characteristics at a low cost is provided. be able to.
The external electrode includes a main electrode portion and an auxiliary electrode portion having a higher resistance than the main electrode portion, and the main electrode portion is located at an edge position of the phosphor layer on the outer periphery of the glass bulb. The auxiliary electrode portion is disposed from the portion corresponding to the edge position of the phosphor layer to the tube central portion side on the outer periphery of the glass bulb. Is preferred.

In this configuration, since the electrons are emitted from the electron radioactive atoms of the phosphor particles by the electric field generated at the auxiliary electrode portion at the time of starting, the dark starting characteristic is improved. Further, since current flows mainly through the main electrode portion during lighting, mercury consumption due to the phosphor layer described above can be suppressed.
Here, it is preferable that the electron radioactive atom is at least one of barium, strontium, and yttrium. Since electrons are emitted from these atoms due to the generation of an electric field from the external electrode, the dark start-up characteristics are improved.

In addition, a protective film for protecting the glass bulb is formed at least from the position corresponding to the edge on the tube end side of the external electrode to the edge position of the phosphor layer on the inner peripheral surface of the glass bulb. Is preferred. Thereby, it can suppress that a glass bulb and mercury react.
A backlight unit according to the present invention includes any one of the above external electrode fluorescent lamps.

  With the above configuration, it is possible to provide a backlight unit with good dark start characteristics.

Hereinafter, an external electrode fluorescent lamp and a backlight unit according to embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
Hereinafter, an external electrode fluorescent lamp according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an external electrode fluorescent lamp according to a first embodiment, in which FIG. 1 (a) is an external view thereof, and FIG. 1 (b) is a schematic view of one end thereof. It is an expanded sectional view.
As shown in FIGS. 1 (a) and 1 (b), an external electrode fluorescent lamp 1 according to the present embodiment includes a glass bulb 2 and a pair of outer peripheral surfaces provided at both ends of the glass bulb 2. External electrodes 3a and 3b are provided.

The glass bulb 2 is produced by sealing both ends of a glass tube made of borosilicate glass (SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —K ₂ O—TiO ₂ ). Is 730 mm. The glass bulb 2 has, for example, an annular cross section, an outer diameter of 4.0 mm, an inner diameter of 3.0 mm, and a thickness of 0.5 mm. The dimensions of the glass bulb 2 are not limited to the above dimensions, but in order to keep the shape of the external electrode fluorescent lamp 1 slim, the outer diameter is 1.8 mm (inner diameter 1.4 mm) to 6.0 mm (inner diameter). 5.0 mm) is preferable.

A protective film 4 is formed on the inner surface of the glass bulb 2 from a position C corresponding to the edge of the external electrode 3a on the glass bulb flange end side. Layer 5 is laminated.
The protective film 4 is made of, for example, yttrium oxide (Y ₂ O ₃ ). The protective film 4 has a role of preventing a phenomenon that a hole is opened in the inner surface of the glass bulb 2 by ion bombardment, that is, a so-called pinhole. The structure of the protective layer 4 is not limited to the above configuration, for example, silica may be formed by (SiO ₂₎ or alumina _(Al 2 _{O 3).} When the protective film 4 is formed of yttrium oxide or silica, mercury hardly adheres to the protective film 4 and mercury consumption is small.

The phosphor layer 5 includes, for example, red phosphor particles (Y ₂ O ₃ : Eu), green phosphor particles (LaPO ₄ : Ce, Tb), and blue phosphor particles (BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn). Formed of rare earth phosphor particles. The configuration of the phosphor layer 5 is not limited to the above configuration, but any one of the phosphor particles may be at least one of electron-radiating atoms such as barium (Ba), strontium (Sr), and yttrium (Y). Contains atoms.

Inside the glass bulb 2, for example, about 2000 μg of mercury and about 7 kPa (20 ° C.) neon / argon mixed gas (Ne 90% + Ar 10%) as a rare gas are sealed. In addition, the structure of mercury and a noble gas is not limited to the said structure, For example, neon krypton mixed gas (Ne95% + Kr5%) may be enclosed as a noble gas.
As shown in FIG. 1B, the external electrodes 3 a and 3 b are composed of an electrode body layer 6 formed on the outer peripheral surface of the glass bulb 2 and a coating layer 7 laminated on the electrode body layer 6.

  The electrode body layer 6 has a thickness d2 of about 3.0 μm. The electrode body layer 6 is mainly composed of silver or copper. The meaning of having silver or copper as a main component includes the case where an alloy of silver and copper is a main component. The main component means that the component is contained most in the composition and has a great influence on the physical properties of the composition. Therefore, compounds other than silver or copper may be included as additives.

  In order to improve the adhesion of the electrode body layer 6 to the glass bulb 2, for example, it is conceivable to add glass frit to the electrode body layer 6. For example, when a glass frit containing 1.0 to 5.0 wt% of bismuth (Bi) is added, the adhesion of the electrode body layer 6 to the glass bulb 2 is improved by the anchor effect of the glass frit. Other additives include ethyl cellulose and the like.

On the other hand, it is preferable not to add environmentally hazardous substances such as lead, antimony, arsenic, and gallium in order to obtain the external electrode fluorescent lamp 1 in consideration of the environment.
Since silver has a small electric resistance, external electrodes 3a and 3b having high conductivity can be obtained when the main component of the electrode body layer 6 is used. Further, when silver is used as the main component of the electrode main body layer 6, the baking operation in the electrode main body layer forming step can be performed in the atmosphere. That is, since silver is difficult to oxidize, it is not necessary to perform a baking operation in an atmosphere such as nitrogen or argon, and the productivity of the external electrode fluorescent lamp 1 is high.

Since copper has the second lowest electrical resistance after silver, the external electrodes 3a and 3b having high conductivity can be obtained even when copper is used as the main component of the electrode body layer 6.
The coating layer 7 is laminated on the outer surface of the electrode body layer 6 and has a thickness d3 of about 7.0 μm. The coating layer 7 contains solder as a main component. The solder for forming the coating layer 7 has a composition of tin: 95.2 wt%, silver: 3.8 wt%, and copper: 1.0 wt%.

Since the solder of the coating layer 7 contains silver, the electrode body layer 6 is unlikely to be eroded by silver. In addition, in order to make silver erosion hard to occur, it is preferable to make silver content into the range of 1.0-8.0 wt%.
Note that the composition of the solder forming the coating layer 7 is not limited to the above, and may include, for example, at least one of bismuth, zinc, lead, and the like. However, in order to make the external electrode fluorescent lamp 1 in consideration of the environment, it is preferable that environmental load substances such as lead and antimony are not included. The coating layer 7 may be formed of a material other than solder. For example, a nickel layer formed by electroless plating may be used.

  In general, silver is easily sulfided in the atmosphere, and copper is easily oxidized. When sulfidation or oxidation occurs, silver and copper increase in electrical resistance. Therefore, the conductivity of the electrode body layer 6 where the electrode body layer 6 is exposed to the air is reduced. However, in the external electrodes 3a and 3b according to the present invention, since the coating layer 7 is laminated outside the electrode body layer 6, the electrode body layer 6 is not easily exposed to the atmosphere. Therefore, silver sulfide and copper oxidation hardly occur, and the conductivity of the external electrodes 3a and 3b hardly decreases.

  In order to make silver sulfide and copper oxidation difficult to occur, it is preferable that the entire outer surface of the electrode body layer 6 is covered with the coating layer 7. However, as long as the influence on the conductivity of the external electrodes 3a and 3b is small, a part of the electrode body layer 6 may be exposed to the atmosphere for production or design reasons. Further, the external electrodes 3a and 3b are not limited to the above configuration, and may have any configuration.

  Next, the formation position of the phosphor layer 5 will be considered. As a result of intensive research by the present inventors, when a phosphor layer is present in a region corresponding to the external electrode in the glass bulb, a starting voltage is applied to the external electrode to generate an electric field, thereby generating an electron emission property in the phosphor layer It has been found that the starting characteristics under dark conditions are improved since electrons are emitted from the atoms and a discharge is induced by the emitted electrons.

  In the above configuration, in the glass bulb 2, the phosphor layer 5 is formed from the position A that enters the distance L from the position B corresponding to the edge of the external electrode 3a on the tube center side. That is, the edge side of the phosphor layer 5 is extended from the position B corresponding to the edge of the external electrode 3a on the tube center side to the position A where the distance L enters the tube end side, and the region AB. Since the electrons are emitted from the phosphor layer existing between them by the electric field generated by the application of the starting voltage, the dark starting characteristic can be improved.

Here, the distance L will be considered. When the distance L is small, the amount of electrons necessary to improve the dark starting characteristic is not emitted, while when the distance L is large, mercury consumption in which the mercury enclosed in the glass bulb is adsorbed by the phosphor layer is lost. Occurs and lamp life is reduced.
From experiments conducted by the present inventors, it was found that the distance L is suitably 1 mm or more and 7 mm or less. This is because if it is less than 1 mm, the amount of electrons emitted by the electric field is small, so that the dark start-up characteristics cannot be sufficiently improved. If it is more than 7 mm, the lamp life is shortened due to mercury consumption. It was.

  In the above description, the configuration on the external electrode 3a side has been described. However, the configuration on the external electrode 3b side may be the same as that on the external electrode 3a side, and corresponds to the edge of the external electrode on the tube center side. The phosphor layer may be formed from the position where it does. Since the external electrode type fluorescent lamp 1 is turned on by alternating current, if at least one of the external electrodes 3a and 3b satisfies the positional relationship between the phosphor layer and the external electrode as described above, the dark starting characteristic is obtained. Can be improved.

Next, a method for manufacturing the external electrode fluorescent lamp according to the first embodiment will be briefly described.
First, a straight tubular glass tube is prepared, and a protective film is formed on the inner surface of the glass tube by a known method. Thereafter, a phosphor layer is formed on the protective film by a known method. Excess portions of the formed phosphor layer are scraped off.

The electrode main body layer 6 is formed by applying a silver paste to the outer peripheral surface of the glass bulb 2 by a known screen printing method and then baking it. The electrode body layer 6 may be formed by a method other than the screen printing method. For example, it may be formed by a method such as gravure printing or dipping.
The coating layer 7 can be formed by a known dipping method (for example, Japanese Patent Application Laid-Open No. 2004-146351). Briefly, for example, the end of the glass bulb 2 is immersed in molten solder in the melting tank. Thus, the external electrode 3 a is formed by coating the electrode body layer 6 with the coating layer 7.

The external electrode 3a is formed at a position adjusted so that the external electrode 3a and the phosphor layer 5 overlap each other by a distance L.
As described above, the external electrode type fluorescent lamp according to the present embodiment can improve the dark start characteristic only by adjusting the relative position between the phosphor layer and the external electrode in the manufacturing process. Since no new material is required for improvement, the manufacturing process is simple and the cost is not increased, the dark start-up characteristics can be improved at low cost.

<Second Embodiment>
Hereinafter, an external electrode fluorescent lamp according to a second embodiment of the present invention will be described. The lamp according to the second embodiment is the same as the lamp according to the first embodiment except that the configuration of the external electrode is the same, and the others are the same. .
The configuration of the external electrode fluorescent lamp according to the second embodiment will be described with reference to FIG. FIG. 2 is an enlarged cross-sectional view schematically showing one end portion of the external electrode fluorescent lamp according to the second embodiment.

The external electrode 10 is formed on the outer periphery of the end portion of the glass bulb 2 and has a main electrode portion 11 and an auxiliary electrode portion 14. The main electrode portion 11 includes an electrode body layer 12 mainly composed of silver or copper and a coating layer 13 mainly composed of solder. The electrode main body layer 12 and the coating layer 13 have the same configuration as the electrode main body layer 6 and the coating layer 7 in the first embodiment, and thus description thereof is omitted. The auxiliary electrode portion 14 is composed of a nesa film (SnO ₂ film) and has a higher resistance than the main electrode portion 11. The auxiliary electrode portion 14 may be formed using an ITO film or a carbon film instead of the nesa film.

The main electrode portion 11 is formed in a region corresponding to the formation start position C of the protective film 4 from the phosphor layer edge position A to the tube end portion side on the outer periphery of the glass bulb 2. The auxiliary electrode portion 14 is formed on the outer periphery of the glass bulb 2 from the phosphor layer edge position A to the tube center side.
Next, the operation of the external electrode fluorescent lamp according to the second embodiment will be described. When the starting voltage is applied to the external electrode 10, an electric field is generated in the main electrode portion 11 and the auxiliary electrode portion 14. Then, electrons are emitted from the electron radioactive atoms contained in the phosphor particles by an electric field generated by applying a voltage to the auxiliary electrode portion 14, and discharge is induced by the electrons, so that the dark start-up characteristic is improved.

  When the lamp is lit, the auxiliary electrode portion 14 has a higher resistance than the main electrode portion 11, so that the lamp current mainly flows through the main electrode portion 11. Mercury consumption due to adsorption to the phosphor layer is likely to occur where the lamp current increases, but the phosphor layer is present in the region corresponding to the auxiliary electrode portion 14 in the glass bulb 2, and the lamp current is higher. Since there is no phosphor layer in the region corresponding to the main electrode portion 11 that flows frequently, mercury consumption due to adsorption to the phosphor layer occurs in the configuration of the external electrode fluorescent lamp according to the second embodiment. The effect of being difficult is obtained.

Next, a method for forming the external electrode 10 of the external electrode type fluorescent lamp according to the second embodiment will be briefly described.
First, the main electrode part 11 is obtained by forming the electrode body layer 12 and the coating layer 13 on the outer periphery of the glass bulb 2 by the same method as described in the first embodiment. Thereafter, forming the auxiliary electrode 14 by drying the coated Nesa film a (SnO ₂₎ to the tube central portion side of the main electrode portion 11. Thus, the external electrode 10 is formed through a simple manufacturing process.

  In the above description, the auxiliary electrode portion 14 is formed over the entire circumference of the glass bulb 2, but the auxiliary electrode portion 14 may not be formed over the entire circumference, and the outer circumference of the glass bulb 2 may not be formed. You may form in only one part. At this time, when the external electrode type fluorescent lamp is used as a light source of a backlight unit of a liquid crystal television, for example, the auxiliary electrode unit is disposed on the rear side of the backlight unit so that light is blocked by the auxiliary electrode unit. Can be suppressed.

<Modification of external electrode fluorescent lamp>
As described above, the present invention has been described based on the embodiments. However, the content of the present invention is not limited to the specific examples shown in the above-described embodiments. For example, the following modifications are possible. Can think.
(1) In the above description, the phosphor layer is formed over the entire inner circumference of the glass bulb in the region corresponding to the external electrode in the glass bulb 2, but the phosphor layer overlapping the external electrode is made of glass. It may not be formed over the entire circumference of the inner surface of the valve. At least, it is sufficient that an amount of the phosphor layer necessary for improving the dark start characteristic is present in a region corresponding to the external electrode in the glass bulb 2.

  (2) FIG. 3 is a schematic enlarged cross-sectional view showing one end of an external electrode type discharge lamp according to a modification. As shown in FIG. 3, the external electrode type discharge lamp according to the modification includes a glass bulb 2 and a pair of cap-like external electrodes 15 arranged at both ends of the glass bulb 2. The external electrode 15 includes an electrode main body layer 16 formed on the outer peripheral surface of the glass bulb 2 and a coating layer 17 laminated on the electrode main body layer 16. The electrode body layer 16 and the coating layer 17 may be formed by, for example, a dipping method.

  (3) FIG. 4 is a schematic enlarged sectional view showing one end of an external electrode type discharge lamp according to another modification. As shown in FIG. 4, an external electrode fluorescent lamp according to another modification includes a glass bulb 2 and a pair of external electrodes 3 a disposed at both ends of the glass bulb 2. In the glass bulb 2, a protective film 4α is formed from a position C corresponding to the end of the external electrode 3a on the tube end side to a formation start position A of the phosphor layer 5α. In this way, the inner surface of the glass bulb 2 between the regions A-C is formed by forming the protective film from the position C corresponding to at least the edge of the external electrode 3a on the tube end side to the formation start position A of the phosphor layer 5α. , The occurrence of pinholes due to discharge can be suppressed.

<Lighting circuit>
Next, the lighting circuit will be described with reference to FIG. FIG. 5 is a configuration diagram of a lighting circuit according to the present embodiment.
The lighting circuit includes a frequency control unit 21, a pulse width modulation (PWM) generation unit 22, a feedback control unit 23, a MOSFET driver 24, an inverter circuit 25, step-up transformers T1 and T2, and a correction inductor. N1 and N2, resonance inductors Lr1 and Lr2, and external electrode fluorescent lamps La1 to LaN.

The frequency control unit 21 controls the frequency of pulses generated by the PWM generation unit 22.
The PWM generation unit 22 generates a pulse whose ON / OFF ratio is adjusted.
The feedback control unit 23 detects the sum of the lamp currents by monitoring the currents flowing through the correction inductors N1 and N2, and controls the PWM generation unit 22 so that the sum of the lamp currents is constant.

The MOSFET driver 24 switches output signals to the gates of the transistors Q <b> 1 to Q <b> 4 of the inverter circuit 25 based on the input signal from the PWM generator 22.
The correction inductors N1 and N2 are elements that correct the voltage applied to the external electrode fluorescent lamps La1 to LaN so that the lamps have the same voltage.
The outputs of the frequency control unit 21 and the feedback control unit 23 are respectively input to the PWM generation unit 22. The output of the PWM generator 22 is input to the MOSFET driver 24, and the MOSFET 24 outputs two systems of channels CH-A and CH-B to the inverter circuit 25.

  The inverter circuit 25 includes transistors Q1 to Q4 and capacitors Cd1 and Cd2, and outputs thereof are input to primary coils of the step-up transformers T1 and T2. One end of the secondary coil of the step-up transformers T1 and T2 is connected in series via the correction inductors N1 and N2. The other ends of the secondary coils of the step-up transformers T1 and T2 are connected to the resonant inductors Lr1 and Lr2, respectively.

The external electrode fluorescent lamps La1 to LaN are connected in parallel and are connected in series with the resonant inductors Lr1 and Lr2. In the equivalent circuit, the external electrode fluorescent lamps La1 to LaN are represented as electrode pairs in which each electrode is connected in series with a capacitance.
The step-up transformers T1 and T2 are driven by an inverter circuit 25. On the secondary side of the step-up transformers T1 and T2, an LCR series resonance circuit including the sum of the capacitance components of the external electrode type fluorescent lamps La1 to LaN and the resonance inductors Lr1 and Lr2. Is configured. The switching frequency of the inverter circuit 25 at the time of starting the lamp is controlled to be lower than the frequency at the time of lighting by the frequency control unit 21, and control is performed to increase the frequency as the lamp temperature rises.

  At startup, the lamp temperature is low, so the voltage in the lamp discharge path is high and the impedance is high. Each of the external electrode type fluorescent lamps La1 to LaN has an impedance for limiting the lamp current. By increasing the impedance at the start in accordance with the lamp temperature, the tube voltage at the time of high lamp impedance is stabilized. As a result, at the time of starting, starting failure due to insufficient starting voltage can be reduced.

Further, at the time of stable lighting, the output efficiency of the lighting circuit can be increased by increasing the frequency and sufficiently operating the above-described LCR series resonance circuit.
Furthermore, since the lamp impedance rises even during dimming, it is possible to design to maintain the output efficiency of the lighting circuit during normal lighting while lowering the operating frequency and suppressing variations in lamp current.

<Backlight unit>
FIG. 6 is an exploded perspective view showing a schematic configuration of a backlight unit and the like according to an embodiment of the present invention, and FIG. 7 is a view for explaining an attached state of the external electrode fluorescent lamp.
The backlight unit 60 according to an embodiment of the present invention is a direct-type backlight unit for a liquid crystal television, and its structure basically conforms to the structure of a conventional backlight unit.

As shown in FIG. 6, the backlight unit 60 includes an envelope 61, a diffusion plate 62, a diffusion sheet 63, and a lens sheet 64, and is used by being arranged on the back surface of the liquid crystal panel 65.
The envelope 61 is a box made of white polyethylene terephthalate (PET) resin, and a substantially square bottom plate is a reflection plate 66 as shown in FIG. A plurality of external electrode fluorescent lamps 1 are arranged inside the envelope 61, and light from these external electrode fluorescent lamps 1 is emitted from the opening of the envelope 61 toward the diffusion plate 62. The

A set of sockets 67 is disposed on the reflecting plate 66 at positions corresponding to the mounting positions of the external electrode fluorescent lamps 1. Each socket 67 is formed by bending a copper alloy plate material such as phosphor bronze, for example, and includes a pair of holding pieces 68a and 68b, and a connecting piece 69 that connects the holding pieces 68a and 68b at the lower edge. Consists of.
The sandwiching pieces 68a and 68b are provided with recesses that match the outer shape of the external electrode fluorescent lamp 1. If the external electrode fluorescent lamp 1 is fitted into the recesses, the leaf spring action of the sandwiching pieces 68a and 68b is achieved. Thus, the external electrode fluorescent lamp 1 is held in the socket 67, and the socket 67 and the external electrodes 3a and 3b are electrically connected.

Power is supplied to the external electrode fluorescent lamp 1 attached to the backlight unit 60 from the lighting circuit of the backlight unit 60 through the socket 67.
The diffusion plate 62 is a plate made of polycarbonate (PC) resin, and is disposed so as to close the opening of the envelope 61. The diffusion sheet 63 is made of polycarbonate resin, and the lens sheet 64 is made of acrylic resin, and is arranged so as to be sequentially superimposed on the diffusion plate 62.

In the external electrode fluorescent lamp 1, since the electrode main body layer 6 is covered with the coating layer 7, when the external electrode fluorescent lamp 1 is fitted into the socket 67, the electrode main body layer 6 hits the edge of the sandwiching pieces 68a and 68b. It is difficult to scrape or peel off.
As described above, the backlight unit according to the present invention has been specifically described based on the embodiment, but the backlight unit according to the present invention is not limited to the direct backlight unit as described above, for example, The backlight unit may be an edge light type (also referred to as a satellite type or a light guide plate type).

  The present invention can be widely applied to external electrode fluorescent lamps and backlight units. In addition, the present invention can provide an external electrode type fluorescent lamp with improved dark starting characteristics, and thus has an extremely high industrial utility value.

It is a figure which shows the structure of the external electrode type | mold fluorescent lamp which concerns on 1st Embodiment, Comprising: FIG. 1 (a) is the external view, FIG.1 (b) is an expanded sectional view which shows the one end part schematically. is there. It is an expanded sectional view which shows roughly the one end part of the external electrode type fluorescent lamp which concerns on 2nd Embodiment. It is a general | schematic expanded sectional view which shows the one end part of the external electrode type discharge lamp which concerns on a modification. It is a general | schematic expanded sectional view which shows the one end part of the external electrode type discharge lamp which concerns on another modification. FIG. 5 is a configuration diagram of a lighting circuit according to the present embodiment. It is a disassembled perspective view which shows schematic structure, such as a backlight unit concerning one Embodiment of this invention. It is a figure explaining the attachment state of an external electrode type fluorescent lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 External electrode type fluorescent lamp 2 Glass bulb 3a, 3b External electrode 4 Protective film 5 Phosphor layer 6 Electrode body layer 7 Coating layer 11 Main electrode part 14 Auxiliary electrode part 60 Backlight unit

Claims (5)

An external electrode fluorescent lamp comprising a tubular glass bulb, a pair of external electrodes disposed on the outer peripheral surfaces at both ends of the glass bulb, and a phosphor layer formed on the inner surface of the glass bulb,
The phosphor layer includes phosphor particles having electron-emitting atoms, and at least the phosphor layer end side near one end of the glass bulb is from the position corresponding to the end edge of the outer electrode on the tube center side to the tube end side An external electrode fluorescent lamp characterized in that the external electrode type fluorescent lamp is extended to a position where it enters 1 mm or more and 7 mm or less. The external electrode has a main electrode part and an auxiliary electrode part having a higher resistance than the main electrode part,
The main electrode portion is disposed from the portion corresponding to the edge position of the phosphor layer on the outer periphery of the glass bulb, from the tube end portion side,
2. The external electrode type fluorescent lamp according to claim 1, wherein the auxiliary electrode portion is disposed on a periphery of the glass bulb from a portion corresponding to an edge position of the phosphor layer to a tube central portion side. lamp. The external electrode fluorescent lamp according to claim 1 or 2, wherein the electron emitting atom is at least one of barium, strontium, and yttrium. A protective film for protecting the glass bulb is formed at least from the position corresponding to the edge on the tube end side of the external electrode to the edge position of the phosphor layer on the inner peripheral surface of the glass bulb. The external electrode type fluorescent lamp according to any one of claims 1 to 3, wherein A backlight unit comprising the external electrode fluorescent lamp according to any one of claims 1 to 4.

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