JPH07153427A - Small fluorescent tube and flat light emitter provided therewith - Google Patents

Abstract

PURPOSE:To provide a small fluorescent tube capable of emitting a sufficiently large quantity of light into a light guide plate with high efficiency and a flat light emitter capable of obtaining high light emitting brightness with relatively small input electric power. CONSTITUTION:A small fluorescent tube 10 comprises a tubular sealing body 20 having an inner diameter of 5mm or less, a pair of electrodes 40 disposed at both ends inside the sealing body 20, and a phosphor layer 50 attached at the inner circumferential surface of the sealing body 20. In a light emitting space enclosure 22 of the sealing body 20, straight portions 25, 26 extending in the different directions are continuous via a bending portion 23. This flat light emitter comprises a light guide plate, the small fluorescent tube 10 where the straight portions 25, 26 of the sealing body 20 are disposed opposite to each other at the peripheral side surfaces in at least two adjacent sides of the light guide plate, and a reflection plate provided in such a manner as to surround a portion except for the portions directly opposite to the light guide plate at the outer peripheral surface of the sealing body 20 of the small fluorescent tube 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact fluorescent tube and a planar light emitting device equipped with this compact fluorescent tube.

[0002]

2. Description of the Related Art For example, a flat light emitting device is used as a backlight of a liquid crystal display used in word processors, personal computers, liquid crystal televisions and the like.

As such a planar light emitting device, as shown in FIG. 8, a so-called edge light system in which a small straight tube type fluorescent tube 1 is arranged along a peripheral side surface 3 on one long side of a rectangular light guide plate 2 is used. Things are known. In this edge light type planar light emitting device, the light emitted from the small fluorescent tube 1 is incident on the inside of the peripheral side surface 3 of the light guide plate 2 and is emitted to the outside from one surface of the light guide plate 2. The liquid crystal panel provided so as to be stacked on the one surface of the light guide plate 2 is irradiated with light.

Such an edge-light type flat light emitting device can be made thinner than a flat light emitting device having another structure, has a relatively high uniformity of luminance distribution, and is small in fluorescent tube. It is excellent in that it is difficult to transfer the heat of the liquid crystal to the liquid crystal panel with low heat resistance.

[0005]

However, in order to increase the emission brightness of the flat light emitting device, it is effective to increase the amount of light incident on the light guide plate 2. The means is to increase the amount of light. A means for increasing the input power to increase the amount of light emitted from the small fluorescent tube 1 itself, and as shown in FIG.
Is disposed along the peripheral side surface on the other side, for example, the peripheral side surface 4 on the long other side facing the peripheral side surface 3, and a means for making light incident from the peripheral side surface 4 in addition to the peripheral side surface 3 of the light guide plate 2 is known. Has been.

However, in the above means, the mercury vapor pressure in the enclosure of the small fluorescent tube 1 rises, which causes
Since the ultraviolet ray emitted from mercury undergoes a self-absorption phenomenon, it is difficult to significantly increase the light emission amount of the small fluorescent tube 1 itself.

On the other hand, in the above means, since the number of electrodes is large as compared with the case where one small fluorescent tube 1 is used, the total amount of energy consumed by the electrodes that does not contribute to light emission is large, Therefore, there is a drawback that the total input electric power becomes considerably large and the efficiency also decreases.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a small fluorescent tube capable of efficiently entering a sufficiently large amount of light into a light guide plate. It is in.

Another object of the present invention is to provide a planar light emitting device which can obtain high light emission brightness with a relatively small input power.

[0010]

The small fluorescent tube of the present invention comprises:
A tube-shaped sealing body having an inner diameter of 5 mm or less in which sealing portions are formed at both ends of the light emitting space surrounding portion, a pair of electrodes provided at both ends inside the sealing body, and provided on an inner peripheral surface of the sealing body. The luminous space surrounding portion of the envelope is characterized in that straight line portions extending in different directions are continuous via a bent portion.

Also, in the small fluorescent tube of the present invention, it is preferable that the electrode has a metal sleeve.

In the flat light emitting device of the present invention, the light guide plate and the peripheral side surfaces of at least two adjacent sides of the light guide plate are arranged so that straight line portions continuous through the bent portion of the envelope face each other. It is characterized by comprising the small fluorescent tube and a reflection plate provided so as to surround a portion of the outer peripheral surface of the sealed body of the small fluorescent tube other than the facing portion directly facing the light guide plate.

In the flat light emitting device of the present invention,
It is preferable that the light guide plate has a reflecting member on one surface thereof, and the reflecting member is formed in a state in which the light reflectance per unit area increases as the distance from the small fluorescent tube increases.

Further, in the flat light emitting device of the present invention,
It is preferable that the light guide plate comprises a reflection plate arranged on one surface, a light diffusion plate arranged on the other surface of the light guide plate, and a prism sheet arranged on the light diffusion plate.

[0015]

According to the small-sized fluorescent tube of the present invention, since the light emitting space surrounding portion of the envelope is continuous with the straight portion extending in different directions through the bent portion, the light emitting space surrounding portion surrounds a part of its periphery. Irradiation of light to a specific illuminated area surrounded by is performed with high efficiency.

According to the flat light emitting device of the present invention, since the linear portion of the small fluorescent tube is arranged so as to face the peripheral side surface on two continuous sides or more of the light guide plate, the light guide plate is provided. Light is incident from the two or more peripheral side surfaces, so that high emission brightness can be obtained.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory sectional view showing the structure of an example of a small fluorescent tube according to the present invention. In this small fluorescent tube 10, sealing parts 21 are formed at both ends of a glass tube-shaped sealing body 20 having an inner diameter of 5 mm or less.

In the light emitting space surrounding portion 22 between the sealing portions 21 and 21 of the sealing body 20, a first straight line portion 25 and a tube axis of the first straight line portion 25 are perpendicular to each other via a bent portion 23. A second straight portion 26 having a tube axis extending in any direction is continuously formed, and the sealing body 20 is formed in an L shape as a whole.

A lead wire 30 extending through the sealing portion 21 is provided in each sealing portion 21 of the sealing body 20, and an electrode 40 is provided at an inner end portion of each lead wire 30. It is provided.

The electrode 40 is composed of a metal sleeve 41 made of stainless steel, and a tungsten film having an emitter made of (Ba, Sr, Ca) O applied on its surface.
And a filament 42 in the form of a heavy coil, and the filament 42 is arranged so as to be housed in the cylindrical hole of the metal sleeve 41.

Specifically, the filament 42 is clamped and fixed at its base end by, for example, the base end of a flatly crushed metal sleeve 41, and its tip does not exceed the tip of the metal sleeve 41. The metal sleeve 41 is disposed in the cylindrical hole of the metal sleeve 41 while being positioned inward. The electrode 40 is held by the lead wire 30 by the base end portion of the metal sleeve 41 sandwiching the tip end portion of the lead wire 30.

By using the electrode 40 having such a metal sleeve 41, it is possible to reduce the amount of scattered substances generated from the filament 42, so that the blackening phenomenon of the encapsulation body 20 is controlled, and as a result, it is used for a long time. A lifetime is obtained.

It is preferable to use lead glass as the material forming the envelope 20. Thereby, even if the inner diameter of the sealing body 20 is 5 mm or less, it has sufficiently high strength.

As the material forming the lead wire 30, it is preferable to use a Dumet wire in which a core wire made of a nickel alloy is coated with copper. The coefficient of thermal expansion of the Dumet wire is very close to the coefficient of thermal expansion of lead glass, and therefore, the lead glass envelope 20 and the lead wire 30 are used.
Since it is possible to directly seal and in a highly airtight state, it is not necessary to adopt a special sealing structure, and the sealing portion 21 is advantageously formed even if the inner diameter of the sealing body 20 is 5 mm or less. can do.

The inner peripheral surface of the envelope 20 has, for example, a color temperature of 6
Y ₂ O ₃ : Eu, La prepared to be 500K
PO ₄ : Ce, Tb and (Sr, Ca, Ba, Mg)
_A phosphor layer 50 made of ₅ (PO ₄ ) ₃ Cl: Eu is formed. The material forming the phosphor layer 50 is not limited to this, and various materials can be used according to the required performance.

Mercury and rare gas are enclosed in the envelope 20. The rare gas sealed in the sealing body 20 is preferably one containing argon and krypton as main components, and in particular, the ratio of krypton in all the rare gases is 10.
It is preferably ˜50 mol%. Further, the filling pressure of the rare gas is preferably 20 to 80 Torr. By satisfying such conditions, the starting voltage is low,
The intensity of the emitted light is high.

When the proportion of krypton is less than 10 mol%, the intensity of emitted light is low. On the other hand, when the ratio of krypton exceeds 50 mol%, the intensity of emitted light becomes low beyond its peak.

Further, in this example, a cylindrical mercury emitting structure 51 made of a powder sintered body containing a titanium-mercury alloy is provided on the outer periphery of the lead wire 30 in the encapsulation body 20. By heating the mercury-releasing structure 51 to release the mercury, the mercury is sealed in the sealing body 20. By providing such a mercury-releasing structure 51, a desired amount of mercury can be reliably sealed in the sealing body 20. However, this mercury-releasing structure 51 is not essential to the present invention, and mercury may be enclosed in the sealing body 20 by other means.

In the small fluorescent tube 10 described above, the sealing body 2 is used.
The first straight line portion 25 and the second straight line portion 26 are continuously formed in the light emitting space surrounding portion 22 of 0 through the bent portion 23, and by supplying power to the lead wire 30,
Since light is emitted in the first straight line portion 25 and the second straight line portion 26 that are continuous through the bent portion 23, the first illuminated area T surrounded by the light emitting space surrounding portion 22 has a first illuminated area T Straight part 25 and second straight part 2
The light from both 6 is irradiated. Therefore, as compared with the case of irradiating with two separate small fluorescent tubes arranged corresponding to each side, the efficiency is high and a sufficient amount of light is applied to the specific illuminated area T. can do.

FIG. 2 is an explanatory view showing the structure of another example of the small fluorescent tube of the present invention. In this small fluorescent tube 15, a sealing portion 21 is formed at each end of a tubular envelope 20 made of lead glass having an inner diameter of 5 mm or less.

In the light emitting space surrounding portion 22 between the sealing portions 21 and 21 of the sealing body 20, a first straight line portion 25 and a tube axis of the first straight line portion 25 are perpendicular to each other via a bent portion 23. Second linear portion 26 having a tube axis extending in any direction is continuously formed, and further, the second linear portion 26 and the first linear portion 25 are opposed to each other via the bent portion 24. A third straight line portion 27 having a tube axis extending parallel to the tube axis of the first straight line portion 25 is continuously formed, and the sealing body 20 is formed in a U shape as a whole.

Each sealing portion 21 of the sealing body 20 is provided with a lead wire 30 made of a dumet wire, which extends through the sealing portion 21, and the inner end portion of each of the lead wires 30 is provided. Is provided with an electrode 45. And the envelope 20
The inner peripheral surface of the color temperature is prepared so as to be _{6500K, Y 2 O 3: Eu} , LaPO 4: Ce, Tb and (Sr, Ca, Ba, Mg ) 5 (PO 4) 3 Cl: Eu
A phosphor layer 50 made of is formed, and mercury and a rare gas are sealed in the sealing body 20.

The electrode 45 is composed of a metal sleeve made of nickel, and the base end portion of the electrode 45 is flatly crushed so that the tip end portion of the lead wire 30 is sandwiched and held by the lead wire 30.

The electrodes 45 made of a metal sleeve have no filament and each of them functions as a cold cathode. Therefore, by using such an electrode 45, the blackening phenomenon is suppressed, and as a result, a long service life is obtained.

The rare gas sealed in the sealing body 20 is preferably one containing argon and neon as main components, and in particular, the ratio of neon to all the rare gases is 40 to 97.
It is preferably mol%. Further, the filling pressure of the rare gas is preferably 40 to 100 Torr. By satisfying such conditions, the starting voltage is low and the intensity of light emitted from the small fluorescent tube is high.

If the proportion of neon is less than 40 mol%, the starting voltage will be high. On the other hand, if the proportion of neon exceeds 97 mol%, the sputtering of the electrode material becomes intense due to neon ions.

In the small fluorescent tube 15 described above, the sealing body 2 is used.
A first straight line portion 25, a second straight line portion 26, and a third straight line portion 27 are formed on the light emitting space surrounding portion 22 of 0 through the two bent portions 23 and 24, respectively, and the lead wire 3
By supplying electric power to 0, the first straight line portion 25 and the second straight line portion 26 that are continuous via the bent portions 23 and 24
Since the light is emitted in the third straight line portion 27, the first straight line portion 25, the second straight line portion 26, and the third straight line portion 26 are provided in the specific illuminated region T surrounded by the light emitting space surrounding portion 22. Light from the three members of the straight line portion 27 is emitted. Therefore, as compared with the case of irradiating with three separate small fluorescent tubes arranged corresponding to each side, the efficiency is high and a sufficient amount of light is irradiated onto the specific illuminated region T. can do.

3A and 3B are explanatory sectional views showing the structure of an example of the planar light emitting device according to the present invention. FIG. 3A is a front sectional view and FIG. 3B is a side sectional view. In this flat light emitting device, for example, a rectangular light guide plate 6 made of acrylic resin is used.
0 and the small fluorescent tube 10 having the configuration shown in FIG. 1, the small fluorescent tube 10 has a peripheral side surface 61 on one long side of the light guide plate 60 and a peripheral side surface 62 on one short side adjacent thereto. 1 straight line portion 25 and second straight line portion 2
6 are arranged so as to face each other.

In the small fluorescent tube 10, reflection is provided so as to surround the outer peripheral surface of the encapsulation member other than the facing portion 28 directly facing the light guide plate 60 and the outer periphery of the space S between the facing portion 28 and the light guide plate 60. A plate 70 is provided, which allows light to be incident on the light guide plate 60 at a high utilization rate.

The light guide plate 60 has a large number of reflecting members (not shown) formed on one surface (lower surface in FIG. 3B) by printing, for example, white ink or white paint. , By this, the side surfaces 61, 62 of the light guide plate 60.
The light that has entered the inside from is reflected upward and is emitted from the other surface (the upper surface in FIG. 3B) of the light guide plate 60.

According to the above planar light emitting device, the small fluorescent tube 10 is provided on the peripheral side surface 61 and the peripheral side surface 62 of the light guide plate 60.
Since the straight line portion 25 and the second straight line portion 26 are arranged so as to face each other, the light is incident on the light guide plate 60 from the two peripheral side surfaces 61 and 62, whereby the high light emission brightness is obtained. Can be obtained.

On the other hand, when two independent straight tube type fluorescent tubes are arranged so that their light emitting regions face the peripheral side surface 61 and the peripheral side surface 62 of the light guide plate 60, the number of electrodes is large. Therefore, the total amount of energy consumed by the electrodes that does not contribute to light emission is large, and therefore the total input power is large, and the two fluorescent lights are present at the corners of the peripheral side surface 61 and the peripheral side surface 62 of the light guide plate 60. It is necessary to avoid abutting the ends of the tubes, which makes the entire device large and complex. However, according to the planar light emitting device of the above embodiment, since the total amount of energy that does not contribute to light emission is small because the number of electrodes is only two, the input power can be made small and the circumference of the light guide plate 60 can be reduced. Since the first straight line portion 25 and the second straight line portion 26 are continuous through the bent portion 23 at the corners of the side surface 61 and the peripheral side surface 62, there is no problem in arrangement and, in the end, the flat surface is obtained. The light emitting device can be made small and simple.

In the above, the reflecting member is the small fluorescent tube 1.
It is preferable that the light reflectance per unit area increases as the distance from 0 increases.

FIG. 4 shows a small fluorescent tube 1 in the light guide plate 60.
FIG. 6 is an explanatory diagram showing arrangement states of reflecting members formed in an area a near 0, an area b near the center of the light guide plate 60, and an area c in the light guide plate 60 away from the small fluorescent tube. As shown in this figure, a large number of circular reflecting members R having the same diameter are arranged in a smaller array pitch in an area b farther from the small fluorescent tube 10 than in an area a close to the small fluorescent tube 10, and the array pitch is smaller than this area b. Is formed in a stepwise changing state so as to become smaller in the area c farther from the small fluorescent tube 10.

As described above, the reflecting member R is the small fluorescent tube 1
Since the reflectance of light per unit area increases as the distance from 0 increases, the amount of light emitted from the other surface of the light guide plate 60 can be controlled for each area. The uniformity of the brightness distribution in the whole can be made high.

The shape of the reflecting member is not limited as long as it is formed in such a state that the reflectance of light per unit area increases as the distance from the small fluorescent tube 10 increases. For example, when a large number of reflecting members are provided, as shown in FIG. 5, the reflecting members R have the same array pitch in each area, but have a smaller fluorescent light than the area a whose diameter is closer to the small fluorescent tube 10. The area b may be larger in the area b farther from the tube 10 and may be larger in the area c farther from the small fluorescent tube 10 than the area b. Also, instead of the reflectance changing stepwise,
The state may be changed gradually.

Further, the light guide plate 60 is located on the portion 71a located on one surface thereof, and on the peripheral side surface 63 on the other long side and the peripheral side surface 64 on the other short side where the small fluorescent tube 10 is not arranged. It is possible to provide the reflection plate 71 formed of the portion 71b or the reflection plate formed of any one of them, whereby a high light utilization rate can be obtained.

Further, a rectangular light diffusing plate 80 made of, for example, polyester resin, polycarbonate resin or acrylic resin can be arranged on the other surface of the light guide plate 60, so that light emitted from the other surface of the light guide plate 60 can be prevented. Light diffuser 80
By passing through, it is possible to make the brightness distribution of light uniform.

On the light diffusion plate 80, for example, a prism sheet 90 having a corrugated surface can be arranged. By using such a prism sheet 90, it is possible to control the direction of light applied to the liquid crystal panel so that the light is directed in a direction perpendicular to the surface of the liquid crystal panel, thereby substantially increasing the brightness. it can.

6A and 6B are explanatory sectional views showing the structure of another example of the planar light emitting device according to the present invention. FIG. 6A is a front sectional view and FIG. 6B is a side sectional view. In this planar light emitting device, a rectangular light guide plate 60 made of acrylic resin,
The small fluorescent tube 15 having the configuration shown in FIG. 2 is provided. The small fluorescent tube 15 has a peripheral side surface 61 on one long side of the light guide plate 60 and a peripheral side surface 62 on a short side adjacent to the peripheral side surface 61.
And the peripheral side surface 63 on the other long side adjacent to this,
The first straight line portion 25, the second straight line portion 26, and the third straight line portion 27 are arranged so as to face each other.

The light guide plate 60 has a large number of reflecting members (not shown) formed on one surface (the lower surface in FIG. 6B) by printing, for example, white ink or white paint. The reflecting member is formed so that the reflectance of light per unit area becomes higher as the distance from the small fluorescent tube 15 increases, as in the flat light emitting device shown in FIG.

The small fluorescent tube 15 is provided with a reflection plate 72 so as to surround a portion other than the facing portion 28 facing the light guide plate 60 on the outer peripheral surface of the envelope and a space S between the facing portion 28 and the light guide plate 60. The light guide plate 60 is provided with a reflection plate 73 including a portion 73a located on one surface of the light guide plate 60 and a portion 73b located on the peripheral side surface 64 on the other short side where the small fluorescent tube 10 is not arranged. It is provided.

A rectangular light diffusing plate 80 made of, for example, polyester resin, polycarbonate resin, or acrylic resin is arranged on the other surface (upper surface in FIG. 6B) of the light guide plate 60, and on the light diffusing plate 80. For example, a prism sheet 90 having a corrugated surface is arranged.

According to the above planar light emitting device, since the small fluorescent tube 15 is arranged along the three side faces 61, 62, 63 of the light guide plate 60, the light guide plate 60 has three side faces 61, 62, 63. Since light is incident from 62 and 63, high emission luminance can be obtained.

Further, as in the above-mentioned embodiment, the light guide plate 60 is provided.
Since there are only two electrodes as compared with the case where three independent straight tube type fluorescent tubes are arranged so that the respective light emitting regions face the peripheral side surface 61, the peripheral side surface 62 and the peripheral side surface 63 of FIG. Since the total amount of energy consumed by the electrodes that does not contribute to light emission is small, the input power can be made small, and the peripheral side surface 61 and the peripheral side surface 62 of the light guide plate 60 can be reduced.
The first straight line portion 25, the second straight line portion
Since the straight line portion 26 and the third straight line portion 27 are continuous with each other, there is no problem in arrangement, and in the end, the planar light emitting device can be made small and simple.

Experimental Example A specific experimental example of the present invention will be described below.

A planar light emitting device A of the present invention was manufactured under the following conditions according to the structure of FIG. <Small fluorescent tube (10)> “Encapsulation body (20)” Material: Lead glass Dimensions: Overall length 170 mm, outer diameter 3.15 mm, inner diameter 2.3
5 mm Straight part length ratio; First straight part (25): Second straight part (26) = 4: 3 "Lead wire (30)"Material; Dumet wire outer diameter; 0.35 mm "Electrode ( 40) ”Metal sleeve (41) Material: Stainless steel Dimensions: Overall length 5 mm, Outer diameter 1.4 mm, Inner diameter 1.2 mm Filament (42) Material: Tungsten“ Phosphor layer (50) ”Material; Y ₂ O ₃ : Eu LaPO ₄ : Ce, Tb (Sr, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ Cl: Eu Thickness: 15 μm “inclusion” Argon, krypton (krypton 10 mol%, encapsulation pressure 50 Torr) Mercury encapsulation amount 4 mg <light guide plate (60)>Dimension; Long side 81 mm, Short side 61 mm, Thickness 4 mm <Light diffusion plate (80)> Dimension: Long side 81 mm, Short side 61 mm, Thickness 0.1 mm

The initial characteristics of the small fluorescent tube (10) are as follows.
Lamp current is 20m in high frequency lighting of 40kHz
A, the lamp voltage is 150V, and the power consumption is 3W.

A small fluorescent tube was produced under the same conditions as the small fluorescent tube (10) except that a straight tube type sealing body having a total length of 101 mm, an outer diameter of 3.15 mm and an inner diameter of 2.35 mm was used. Flat light emitting device A except that a fluorescent tube is used
Under the same conditions as above, the planar light emitting device C having the configuration of FIG. 9 was produced. The initial characteristics of the above-mentioned small fluorescent tube are a lamp current of 20 mA, a lamp voltage of 100 V, and a power consumption of 2 W in high frequency lighting of 40 kHz.

Regarding the above-mentioned planar light emitting devices A and C,
The average surface luminance when a small fluorescent tube was turned on under the conditions of lamp currents of 12 mA, 15 mA, and 20 mA was measured. The results are shown in Fig. 7.

As is apparent from FIG. 7, the surface average luminance of the planar light emitting device A according to the present invention is about 1.6 times the surface average luminance of the planar light emitting device C, which is sufficiently high. Moreover, the luminance per 1 W of power consumption at a lamp current of 20 mA is 2100 nt (4200 nt) for the planar light emitting device C.
/ 2W), whereas the planar light-emitting device A has 2500
nt (7500 nt / 3 W), and the brightness per unit power consumption was high.

A flat light emitting device E having the structure shown in FIG. 10 was manufactured under the same conditions except that two small fluorescent tubes used for the flat light emitting device C were used, and two flat fluorescent devices were manufactured under the condition of a lamp current of 20 mA. The surface average luminance when the small fluorescent tube was turned on was measured and found to be 8000 nt. However, the power consumption of the flat light emitting device A is 3.0 W, whereas the power consumption of the flat light emitting device E is 4.0 W, which is a large power consumption and the brightness per 1 W of power consumption is high. Was 2000 nt (8000 nt / 4 W), and the brightness per unit power consumption was low.

A planar light emitting device B of the present invention was manufactured under the following conditions according to the structure of FIG. <Small fluorescent tube (15)>"Encapsulation body (25)" Material: Lead glass Dimensions: Overall length 240 mm, outer diameter 3.15 mm, inner diameter 2.3
5 mm length ratio of straight line portion; first straight line portion (25): second straight line portion (26): third straight line portion (27) = 4: 3:
4 "Lead wire (30)" Material: Dumet wire outer diameter: 0.35mm "Electrode (45)" Material: Stainless steel Dimensions: Overall length 5mm, outer diameter 1.4mm, inner diameter 1.2mm "Phosphor layer (50)" Material: Y ₂ O ₃ : Eu LaPO ₄ : Ce, Tb (Sr, Ca, Ba, Mg) ₅ (PO ₄ ) ₃ Cl: Eu Thickness: 15 μm “Encapsulation” Argon, neon (neon 95 mol%, enclosure pressure) 80To
rr) Mercury enclosed amount 4 mg <Light guide plate (60)> Dimension: Long side 81 mm, Short side 61 mm, Thickness 4 mm <Light diffuser (80)> Dimension: Long side 81 mm, Short side 61 mm, Thickness 0.1 mm

The initial characteristic of the small fluorescent tube 15 is 40
In high frequency lighting of kHz, the lamp current is 5 mA, the lamp voltage is 490 V, and the power consumption is 2.45 W.

A small fluorescent tube was prepared under the same conditions as the small fluorescent tube (15) except that a straight tube type sealing body having a total length of 100 mm, an outer diameter of 3.15 mm and an inner diameter of 2.35 mm was used. Flat light emitting device B except that a fluorescent tube is used
Under the same conditions as above, the planar light emitting device D having the configuration of FIG. 9 was produced. The initial characteristics of the above-mentioned small fluorescent tube are a lamp current of 5 mA, a lamp voltage of 260 V, and a power consumption of 1.3 W in high frequency lighting of 40 kHz.

With respect to the above planar light emitting devices B and D, the average surface luminance when the small fluorescent tube was turned on under the condition of the lamp current of 5 mA was measured, and it was found that the average surface luminance of the planar light emitting device D was 2000 nt. The surface emission brightness of the planar light emitting device B according to the present invention was 5,500 nt, which was sufficiently high. Moreover, the brightness per 1 W of power consumption is
Planar light emitting device D has 1530nt (2000nt / 1.3
W), whereas the planar light emitting device B has 2250nt
(5500nt / 2.45W), and the brightness per unit power consumption was high.

[0067]

As described above, according to the small fluorescent tube of the present invention, the light emitting space surrounding portion of the sealing body is provided with the bent portion through the bent portion.
Since the above-mentioned straight line portion is formed, the light emitting space surrounding portion surrounds the surrounding area with a specific illuminated area.
It is possible to irradiate light from different directions by the above straight line portions. Therefore, by disposing the light guide plate in the specific illuminated region, a sufficient amount of light can be incident on the light guide plate.

According to the planar light emitting device of the present invention, such a small fluorescent tube is arranged such that its straight line portion faces the peripheral side surfaces of two or more continuous sides of the light guide plate.
High emission brightness can be obtained.

Further, compared to the case where two or more independent straight tube type fluorescent tubes are arranged so that their light emitting regions are opposed to the peripheral side surfaces on two or more sides of the light guide plate, the electrodes are different from each other. Since there are only two, the total amount of energy consumed by the electrodes that does not contribute to light emission is small, so that the input power can be made small, and the bent portions are formed at the corners between the adjacent side surfaces of the light guide plate. Since the straight line portions are continuous with each other, the ends of the fluorescent tubes do not collide with each other, and in the end, the planar light emitting device can be made small and simple.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing the structure of an example of a small fluorescent tube according to the present invention.

FIG. 2 is an explanatory cross-sectional view showing the configuration of another example of the small fluorescent tube according to the present invention.

FIG. 3 is an explanatory diagram showing a configuration of an example of a planar light emitting device according to the present invention.

FIG. 4 is an explanatory view showing an example of an arrangement state of a reflecting member formed on one surface of a light guide plate in the planar light emitting device according to the present invention.

FIG. 5 is an explanatory view showing another example of the arrangement state of the reflecting member formed on one surface of the light guide plate in the flat light emitting device according to the present invention.

FIG. 6 is an explanatory diagram showing the configuration of another example of the planar light emitting device according to the present invention.

FIG. 7 is a diagram showing a relationship between a lamp current and surface average luminance in planar light emitting devices A and C according to an experimental example.

FIG. 8 is an explanatory diagram showing a configuration of an example of a conventional edge light type planar light emitting device.

FIG. 9 is an explanatory diagram showing the configuration of another example of the conventional edge-light type planar light emitting device.

[Explanation of symbols]

1,5 Small fluorescent tube 2 Light guide plate 3,4 Circumferential side surface 10,15 Small fluorescent tube 20 Sealing body 21 Sealing portion 22 Luminous space surrounding portion 23,24 Bending portion 25 First straight portion 26 Second straight portion 27 Third straight portion 28 Opposing portion 30 Lead wire 40,45 Electrode 41 Metal sleeve 42 Filament 50 Phosphor layer 51 Mercury emission structure 60 Light guide plate 61, 62, 63, 64 Circumferential side surface 70, 71, 7
2,73 Reflector 80 Light diffuser 90 Frhythm sheet R Reflective member S Void T Illuminated area

Claims (5)

[Claims] 1. A tubular type sealing body having an inner diameter of 5 mm or less in which sealing portions are formed at both ends of a light emitting space surrounding portion, a pair of electrodes provided at both ends in the sealing body, and the sealing body of the sealing body. And a phosphor layer provided on the inner peripheral surface, wherein the light emitting space surrounding portion of the encapsulant is characterized in that linear portions extending in different directions are continuous through a bent portion. tube. 2. The small fluorescent tube according to claim 1, wherein the electrode has a metal sleeve. 3. The light guide plate, and each of the peripheral side surfaces on at least two adjacent sides of the light guide plate is arranged such that a continuous straight line portion is opposed to each other via a bent portion of the envelope. Item 2. A small fluorescent tube according to item 2, and a reflecting plate provided so as to surround a portion other than a facing portion that directly faces the light guide plate on the outer peripheral surface of the sealed body of the small fluorescent tube. Flat light emitting device. 4. The flat light emitting device according to claim 3, wherein the light guide plate has a reflecting member on one surface thereof, and the reflecting member is separated from the small fluorescent tube so as to reflect light per unit area. A flat light emitting device, characterized in that the flat light emitting device is formed so as to have a high rate. 5. The flat light emitting device according to claim 3, wherein the reflection plate is disposed on one surface of the light guide plate, and the light diffusion plate is disposed on the other surface of the light guide plate. A planar light emitting device comprising a prism sheet arranged on the light diffusion plate.