JP2002025506A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device wherein the luminous efficiency of a lamp is improved. SOLUTION: This is a light emitting device which is equipped with a sealed discharge container 10, rare gas 16 enclosed in the discharge container 10, dielectric layers 14 formed on inner faces of a translucent front substrate 11 and transmissive rear substrate 12 so as to cover an electrode 13, and fluorescent substance layers 15 formed on the dielectric layers 14. In the light emitting device 100, the first electrostatic capacity of a front face fluorescent substance layer 15a and the second electrostatic capacity of a rear face fluorescent substance layer 15b are different from each other, and the first composite electrostatic capacity which a dielectric layer 14a and the front face fluorescent substance layer 15a have and the second composite electrostatic capacity which a dielectric layer 14b and the rear face fluorescent substance layer 15b have are substantially equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, and more particularly, to a light emitting device used for a backlight such as a liquid crystal display or a lighting device.

[0002]

2. Description of the Related Art A conventional light emitting device (parallel fluorescent lamp) is disclosed, for example, in Japanese Patent Application Laid-Open No. 8-287869. Light emitting device 1000 disclosed in this publication
Is schematically shown in FIG.

[0003] A lamp 1000 shown in FIG. 8 is a so-called dielectric barrier discharge lamp, and has a front glass substrate 111.
And a rear glass substrate 112, a hermetic discharge vessel 110, a rare gas (xenon) 116 sealed in the discharge vessel 110, and a front glass substrate 111 and a rear glass substrate 112. Electrode 1
13 and a front glass substrate 111 so as to cover the electrodes 113.
And a dielectric layer 114 formed on each of the rear glass substrate 112 and a phosphor layer 115 formed on the dielectric layer 114.

The front glass substrate 111 is made of, for example, soda glass or the like. The front glass substrate 111 and the rear glass substrate 112 are arranged to face each other with a discharge gap secured by a glass spacer 118. A frit glass 117 is formed on the outer surface of the glass spacer 118, and the frit glass 117 seals the discharge vessel 110.

The electrodes 113 provided on the front glass substrate 111 and the rear glass substrate 112 are made of silver or ITO.
A dielectric layer 114 (thickness: 50 μm) made of translucent lead glass or the like is formed on the front glass substrate 111 and the back glass substrate 112 so as to cover the electrodes 113. It is applied in a shape. Dielectric layer 11
A phosphor layer 115 which is excited by ultraviolet radiation and emits visible light is applied in a film shape on the surface of No. 4. When an alternating voltage of a sine wave or a pulse wave is applied between the electrode 113a on the front glass substrate 111 and the electrode 113b on the rear glass substrate 112, discharge occurs in the discharge vessel 110 in which the gas 116 is sealed. As a result, the phosphor layer 115 is excited by ultraviolet radiation from the discharge to emit visible light, thereby causing the lamp 1000 to emit light.

In the case of the above-described conventional lamp 1000,
In order to extract as much visible light as possible from the front glass substrate 111, the thickness of the phosphor layer (front phosphor layer) 115a formed on the front glass substrate 111 side is reduced, and the fluorescence formed on the rear glass substrate 112 side is reduced. Body layer (back phosphor layer)
The thickness of 115b is increased. The reason for this is to reduce the thickness of the front phosphor layer 115a so that light emitted from the inside of the discharge vessel 110 to the front glass substrate 111 is not blocked by the front phosphor layer 115a as much as possible. This is because the thickness of the rear phosphor layer 115b, which is not on the front glass substrate 111 side, is increased to make the ultraviolet radiation generated in the discharge vessel 110 as much visible light as possible, thereby improving the luminous efficiency. In the above publication, the lamp 10
00, the thickness of the front phosphor layer 115a is 5 to 20 μm.
m, and the thickness of the back phosphor layer 115b is preferably set to 30 μm or more.

[0007]

As shown in FIG. 9A, the inventor of the present invention examined the relationship between the relative luminance of the lamp 1000 and the thickness of the back phosphor layer 115b, as shown in FIG. Electrode 1 of lamp 1000 formed only
An experiment was conducted in which a lamp power supply 20 (lamp power: 2 W) was added to 13 and the relative luminance of the lamp 1000 was examined.
This result is shown in FIG. BaAl ₁₂ O ₂ : Mn is used as a phosphor constituting the back phosphor layer 115b, and the thickness of the back phosphor layer 115b is from about 10 μm to about 100 μm.
m, and the relative luminance for each film thickness was examined.

As shown by the dotted line in FIG. 9B, the inventor of the present application has made the lamp 10 thicker by increasing the thickness of the phosphor layer 115 when the thickness of the phosphor layer 115 is relatively increased.
The relative luminance of 00 did not decrease, and it was expected that the relative luminance would increase. The reason is as follows. As shown in FIG. 10, the phosphor layer (light-emitting layer) 115 is formed in a state in which phosphor particles (diameter: about 5 to 20 μm) are arranged with a gap therebetween. Therefore, the electrons (e) generated at the time of discharge are
It is considered that the phosphor layer 115 does not affect the electrons (e) generated at the time of discharge even when the phosphor layer 115 is thickened. This is because the relative brightness of the lamp 100 is expected to approach 100% as the thickness increases.

However, surprisingly, FIG.
As shown by the solid line in (b), the actual measurement results show that the relative luminance increases up to a film thickness of 30 μm, but decreases after the film thickness exceeds 30 μm. . Conventionally, the effect of the thickness of the phosphor layer 115 on the discharge of the lamp 1000 has not been considered, but when estimated from the result indicated by the solid line in FIG.
It is considered that the change in the thickness of the phosphor layer 115b affects the ultraviolet emission efficiency.

In the case of the conventional lamp 1000, FIG.
As schematically shown in FIG. 1A, a dielectric layer 114 and a phosphor layer 115 are sequentially formed on an electrode 113, and the phosphor constituting the phosphor layer 114 is a dielectric.
When the configuration shown in FIG. 1A is represented by an equivalent circuit, FIG.
As shown in (b), a configuration in which capacitors made of respective layers are connected in series is obtained.

As can be understood from the equivalent circuit shown in FIG. 11B, the ultraviolet luminous efficiency of the lamp 1000 depends on the capacitance CDf of the front dielectric layer 114a and the capacitance of the rear dielectric layer 114b. In addition to the capacitance CDb, the capacitance CPf of the phosphor layer 115a on the front side and the phosphor layer 1 on the back side
It is also affected by the capacitance CPb of 15b. Lamp 10
00 are CDf, CDb, CPf, CP
b and the capacitance including stray capacitance,
When determining the capacitance of the entire lamp 1000, it is desirable to optimize these capacitances.

In the structure shown in FIG. 11A, the thickness of the front phosphor layer 115a is set to 20 μm,
FIG. 12 shows the relationship between the lamp voltage and the lamp current when the thickness of 15b is 30 μm. The thickness of the front dielectric layer 114a and the thickness of the rear dielectric layer 114b are both 50 μm.

As can be seen from FIG. 12, a sinusoidal alternating voltage (lamp voltage: 200 V / di) is applied to the electrode 113.
Despite the application of v), the symmetry of the lamp current is lost, and the lamp current when the applied voltage is positive (upper graph) is negative when the applied voltage is lower (lower graph).
Lamp current. That is, the positive and negative peak values of the lamp current are different.

If the positive and negative peak values of the lamp current are different, one of the lamp currents becomes larger or smaller than the other. According to the xenon emission process in the vacuum ultraviolet region, as shown in FIG. 13, xenon in the ground state is excited by the resonance line excitation level (8.5).
eV), the metastable state (8.3 e)
V), then excimer molecule formation occurs, followed by 172 nm ultraviolet emission. This 172 nm
Is converted into visible light by the phosphor layer 115. In the xenon emission process, when the lamp current is large, xenon is excited by the resonance line excitation level (8.5 e).
Excitation to a level higher than V) causes infrared light emission not contributing to final visible light emission, resulting in energy loss and reduction in luminous efficiency of the lamp. On the other hand, when the lamp current is small, the probability of excitation to the resonance line excitation level or the level of the metastable state decreases, and as a result, the luminous efficiency of the lamp decreases.

The result shown in FIG.
It is presumed that the symmetry of the capacitance between the front side and the back side caused by the difference in the thickness of each of 5a and the back phosphor layer 115b was lost. However, if the thicknesses of the front phosphor layer 115a located on the front side and the back phosphor layer 115b located on the back side are made equal to match the positive and negative peak values of the lamp current, the front phosphor layer Since the thickness of 115a is not reduced, the amount of light emitted from inside the discharge vessel 110 to the front glass substrate 111 is reduced, and as a result, the luminous efficiency of the lamp is reduced.

The present invention has been made in view of the above points, and a main object of the present invention is to provide a light emitting device with improved luminous efficiency of a lamp.

[0017]

According to the present invention, there is provided a light emitting device comprising: a sealed discharge vessel comprising a light-transmitting front substrate; and a rear substrate disposed opposite to the front substrate; A rare gas sealed in a container, formed on each inner surface of the front substrate and the rear substrate,
An electrode to which an alternating voltage is applied, a dielectric layer formed on the inner surface of each of the front substrate and the rear substrate so as to cover the electrode, and a phosphor layer formed on the dielectric layer And a first capacitance of the front phosphor layer located on the dielectric layer on the front substrate, and a first capacitance on the dielectric layer on the back substrate Different from the second capacitance of the back phosphor layer, the first combined capacitance of the dielectric layer on the front substrate and the front phosphor layer, and the dielectric layer on the back substrate And a second surface of the back phosphor layer
It is characterized by being substantially equal to the combined capacitance.

It is preferable that a value obtained by dividing the smaller one of the first combined capacitance and the second combined capacitance by the larger one of the first combined capacitance and the second combined capacitance is not more than 1 and not less than 0.86.

The capacitance of the entire lamp defined by the first combined capacitance and the second combined capacitance is 1 pF / c.
It is preferably m ^{2 to} 50 pF / cm ² .

In one embodiment, the relative permittivity of the front phosphor layer and the relative permittivity of the back phosphor layer are equal, and the thickness of the front phosphor layer is greater than the thickness of the back phosphor layer. thin.

At least one of the front substrate and the rear substrate may be connected in series to a capacitor for adjusting the first combined capacitance and the second combined capacitance substantially equally.

The electrodes are a plurality of linear electrodes or mesh electrodes parallel to each other, and the total area of the electrodes on the front substrate is smaller than the total area of the electrodes on the rear substrate. preferable.

The electrodes are a plurality of linear electrodes or mesh electrodes parallel to each other, and the dielectric layer on the front substrate has a dielectric layer located on the electrodes in a region located between the electrodes. It is preferable to have a portion of 50% or less and 0% or more of the thickness of the layer.

The electrodes are a plurality of linear electrodes or mesh electrodes parallel to each other, and the phosphor layer formed on the dielectric layer of the back substrate is provided in a region located above the electrodes. 5% or more of the thickness of the phosphor layer formed on the dielectric layer located between the electrodes.
It is preferable to have a portion having a thickness of 5% or less.

According to the present invention, the first combined capacitance of the dielectric layer and the front phosphor layer on the front substrate and the second combined capacitance of the dielectric layer and the back phosphor layer on the back substrate Are configured to be substantially equal to
It is possible to appropriately control the positive and negative peak values of the lamp current, and as a result, it is possible to provide a light emitting device with improved luminous efficiency of the lamp. The first combined capacitance and the second
The value obtained by dividing the smaller of the combined capacitance and the larger of the combined capacitances is, for example, 1 or less and 0.86 or more,
Preferably it is 1 or less and 0.9 or more, more preferably 1 or less and 0.97 or more. The capacitance of the entire lamp is 1
If it is ^{pF / cm 2 ~50pF / cm 2} , it is possible to further improve the luminous efficiency of the lamp. A configuration in which at least one of the front substrate and the rear substrate is connected in series to the capacitor may make the first combined capacitance substantially equal to the second combined capacitance.

As the electrodes, a plurality of linear electrodes or mesh electrodes parallel to each other can be used, and the total area of the electrodes on the front substrate is smaller than the total area of the electrodes on the rear substrate. In this case, the amount of visible light emitted from the front substrate can be increased. Also, the thickness of the portion of the dielectric layer on the front substrate located between the electrodes is less than half the thickness of the electrodes on the front substrate (50% or less and 0% or more).
With such a configuration, visible light emitted from the front substrate can be further increased. Further, the thickness of the portion of the phosphor layer formed on the dielectric layer located on the electrode is 5% to 95% of the thickness of the portion of the phosphor layer located between the electrodes. When configured, the luminance of the phosphor layer can be made uniform.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, components having substantially the same function are denoted by the same reference numeral for the sake of simplicity.

The light emitting device according to the first embodiment will be described with reference to FIGS. FIG. 1 schematically shows a configuration of a light emitting device (flat fluorescent lamp) 100 of the present embodiment.

The light emitting device 100 includes a sealed discharge vessel 10 composed of a light-transmitting front substrate 11 and a rear substrate 12, and a rare gas (for example,
(Xenon) 16, an electrode 13 formed on each of the front substrate 11 and the back substrate 12, and a dielectric layer 14 formed on each of the front substrate 11 and the back substrate 12 so as to cover the electrode 13. And a phosphor layer (light emitting layer) 15 formed on the dielectric layer 14. The opposing electrodes 13 are each electrically connected to a lamp lighting power supply 20, and a sine wave having a frequency of 20 kHz is applied between the opposing electrodes 13, for example.

In this embodiment, each of the front substrate 11 and the rear substrate 12 is a glass substrate, and is made of, for example, soda-lime glass. Front substrate 11
And the rear substrate 12 are opposed to each other with a predetermined discharge gap (for example, 0.55 mm) secured by a glass spacer 18 (for example, 0.55 mm). The glass spacer 18 has a function of fixing the discharge gap length of the lamp 100, and is made of, for example, soda lime glass. Glass spacer 18
A frit glass 17 serving as a sealing material is formed on an outer surface of the discharge vessel 10 by the frit glass 17.
Are sealed. Note that the exhaust pipe 19 in FIG. 1 is used during the lamp manufacturing process, and is not particularly necessary for the lamp 100.

The electrodes 13a and 13b provided on the front substrate 11 and the rear substrate 12 are made of, for example, silver. Dielectric layers 14a and 14b formed on front substrate 11 and rear substrate 12 so as to cover electrode 13
Is made of, for example, translucent lead glass, and phosphor layers 15a and 15b which are excited by ultraviolet radiation and emit visible light are formed on the surfaces of the dielectric layers 14a and 14b, respectively.

The phosphor layer (light emitting layer) 15 (15a, 15
b) is composed of, for example, a phosphor for PDP,
The phosphor used for the phosphor layer 15 is, for example, 4
Europium-activated barium magnesium aluminate phosphor having a center wavelength of light emission near 55 nm, magnesium-activated aluminate phosphor with a center wavelength of light emission near 515 nm, and a center wavelength of light emission near 590 nm, 610 nm and 630 nm A mixed phosphor of europium-activated yttrium gadolinium borate phosphor is exemplified. In the present embodiment, the dielectric layer 1 on the front substrate 11 is
4a, a front phosphor layer 15a located on
Back phosphor layer 15 located on the upper dielectric layer 14b
b is made of the same phosphor (or the same mixed phosphor) having the same relative permittivity.

In the lamp 100 of the present embodiment, the thickness of the front phosphor layer 15a is smaller than the thickness of the back phosphor layer 15b in order to increase the light extraction efficiency from the front substrate 11 side. As a result, the first capacitance (the capacitance of the front-side phosphor layer 15a: CP) of the front phosphor layer 15a located on the dielectric layer 14a on the front substrate 11
f) is different from the second capacitance (capacitance of the backside phosphor layer 15b: CPb) of the backside phosphor layer 15b located on the dielectric layer 14b on the backside substrate 12. (CPf ≠ CPb). In this embodiment,
In order to maximize the light extraction efficiency, the thickness of the front phosphor layer (front phosphor layer) 15a is set to, for example, 20 μm, and the thickness of the back phosphor layer (back phosphor layer) 15b is set to, for example, 6 μm.
It is 0 μm. In addition, these film thicknesses are examples,
The optimum film thickness that maximizes the light extraction efficiency differs depending on the lamp structure, the type and pressure of the rare gas to be sealed, or the lighting method.

In the present embodiment, the thickness of the front phosphor layer 15a is configured to be smaller than the thickness of the rear phosphor layer 15b, while the thickness of the dielectric layer 14 on the front substrate 11 is reduced.
a and the first combined capacitance of the front phosphor layer 15a (the combined front capacitance: Cf) and the second combined capacitance of the dielectric layer 14b and the back phosphor layer 15b on the back substrate 12 ( And the back surface combined capacitance: Cb). First combined capacitance (C
f), the second combined capacitance (Cb), and the value obtained by dividing the smaller of the combined capacitance by the larger of the two is, for example, 1 or less and 0.86 or more, preferably 1 or less and 0.9 or more And more preferably 1 or less and 0.97 or more.

Next, the operation of the lamp 100 of this embodiment will be described.

First, the electrode 13a on the front substrate 11 and the electrode 13a on the rear substrate 12 are
When a sine wave or pulse electrode application voltage is applied between the electrode 13 and the electrode b, the dielectric layer 14 and the phosphor layer 15 on the electrode 13 are polarized. As a result, an electric field is generated in the discharge space (discharge gap) 10. Occurs. Thereafter, the rare gas (for example, xenon gas) sealed in the discharge vessel 10 starts a discharge in a minute space, whereby the phosphor layer 15 or the dielectric layer 14 is started.
The electric charge is accumulated on the surface of. The discharge ends when the combined electric field of the internal electric field due to the accumulation of the electric charges and the external electric field in the opposite direction due to the polarization of the dielectric layer 14 and the phosphor layer 15 falls below the discharge sustaining electric field.

Thereafter, a reverse voltage is applied between the electrode 13a and the electrode 13b. At this time, when the sum of the electric field due to the electric charge accumulated on the surface of the phosphor layer 15 or the dielectric layer 14 and the electric field generated between the discharge gaps by the electrode applied voltage exceeds the discharge start electric field, the discharge starts again. Will be done. Thus, each time the application direction of the electrode application voltage changes, the start and the pause of the discharge are repeatedly performed.

When the xenon gas is discharged in the discharge vessel 10, ultraviolet radiation such as resonance line emission (center wavelength: 147 nm) and excimer molecule emission (center wavelength: 172 nm) is generated. Ultraviolet light generated by the discharge is converted into visible light by the phosphor of the phosphor layer 15, and the visible light passes through the dielectric layer 14 and is irradiated outside the front substrate 11 and the back substrate 12.

The center wavelength (172 nm) of excimer molecule emission of ultraviolet radiation generated by xenon discharge is longer than the center wavelength (147 nm) of resonance line emission. Less loss.
That is, the conversion loss is reduced according to the Stokes law. Further, since excimer light emission hardly absorbs itself, ultraviolet light can reach the phosphor layer 15 without attenuating. Therefore, in order to obtain visible light with high efficiency, it is necessary to increase the efficiency of excimer light emission.
In order to increase the efficiency of excimer light emission, the number of atoms in the metastable state may be increased as much as possible.

The generation of excimer light emission will be described first.
Electrons generated by the discharge in the discharge vessel 10 are sufficiently accelerated by the electric field between the discharge gaps. As a result, some of the electrons excite the xenon atom to a metastable state, and then one metastable atom undergoes a three-body collision with two ground state atoms, thereby One excimer molecule and one ground state atom result. When the excimer molecule generated at this time dissociates into two ground state atoms, excimer emission of 172 nm is emitted. Therefore, by increasing the number of atoms in the metastable state, the efficiency of excimer light emission can be increased, and as a result, the light emission efficiency of the lamp can be improved.

In the lamp 100 of the present embodiment, the first combined capacitance (front combined capacitance: Cf) is substantially equal to the second combined capacitance (back combined capacitance: Cb). Thus, unlike the conventional lamp 1000, the positive and negative peak values of the lamp current can be matched. Therefore, both the positive and negative peak values of the lamp current can be optimized so that the condition that maximizes the number of atoms in the metastable state is generated, so that the excimer luminous efficiency can be increased, and as a result, the lamp Luminous efficiency can be improved. First combined capacitance (Cf)
And the second combined capacitance (Cb), and the value obtained by dividing the smaller of the combined capacitance by the larger of the two, for example, is 0.1 or less.
86 or more, preferably 1 or less and 0.9 or more,
More preferably, it is 1 or less and 0.97 or more.

The first combined capacitance (Cf), the second combined capacitance (Cb), and the total capacitance (Ctotal) of the lamp 100 are expressed by the following formula (I).
4a, the capacitance (CPf) of the phosphor layer 15a, the capacitance (CDb) of the dielectric layer 14b, and the capacitance (CPb) of the phosphor layer 15b. .

1 / Ctotal = 1 / CDf + 1 / CPf + 1 / CPb + 1 / CDb Formula (I) where Ctotal, CDf, CPf, CDb, and CP
b indicates the capacitance per unit area. The capacitance per unit area can be calculated from relative dielectric constant (ε) × dielectric constant of vacuum (ε ₀ ) / film thickness (t).

Table 1 below shows the lamp 100 of this embodiment.
Conditions for No. 1 to No. 3, and
The first combined capacitance (Cf), the second combined capacitance (Cf)
b), the capacitance (Ctotal) of the entire lamp 100, and the ratio of Cb to Cf (Cb / Cf).

[0045]

[Table 1] ΕDf and εDb in Table 1 are the dielectric layers 14
a and 14b represent the relative dielectric constants of εPf and εPb
Represents the relative permittivity of the phosphor layers 15a and 15b, respectively. Also, tDf, tDb, tPf, and tDf
Pb represents the thicknesses of the dielectric layers 14a and 14b and the phosphor layers 15a and 15b, respectively.

The structure will be specifically described with reference to No. 2 as an example. (A) The relative dielectric constant (εDf) of the front dielectric layer 14a (lead glass) is 8 and the thickness (tDf) is 160 μm;
The relative permittivity (εPf) 3 and the thickness (tPf) of the front phosphor layer 15a (three wavelengths (for three types of PDPs) for PDP) are 20 μm;
(C) The relative permittivity (εPb) 3 and the thickness (tPb) of the rear phosphor layer 15 b (three wavelengths for PDP (mixture of three types))
m; and (d) the relative dielectric constant (εDb) of the rear dielectric layer 14b (lead glass) is 8 and the thickness (tDb) is 50 μm.

As can be seen from Table 1, No. 1 to No. 3
Are configured such that the first combined capacitance (Cf) and the second combined capacitance (Cb) are substantially equal, and the value of Cb / Cb is 1 or less and 0.97 or more. The value is in the range. The configuration of the lamps of No. 1 to No. 3 is C
f and Cb are made substantially equal, and
Since the thickness of the front phosphor layer 15a is smaller than the thickness of the rear phosphor layer 15b, the efficiency of excimer light emission can be increased, and the light extraction efficiency from the front substrate 11 can be increased. . The value of Cb / Cb calculated from the configuration of the lamp disclosed in the above publication was 0.859 or less for each lamp.

The inventors of the present application examined the relationship between the capacitance of the entire lamp and the luminous efficiency by changing the capacitance (Ctotal) of the entire lamp of the lamp 100. The luminous efficiency (lm / W) is a value obtained by dividing the total luminous flux (lm) by the lamp power (W). In this example, the voltage applied to the discharge gap is set to 350 Vrms and the frequency 2 is applied in consideration of the effect of the voltage drop due to the dielectric layer 14 and the phosphor layer 15.
Lighting was performed by applying a 0 kHz sine wave applied voltage. The results are shown in Table 2 and FIG.

[0049]

[Table 2] From Table 2 and FIG. 2, when the capacitance (capacitance per unit area) of the entire lamp is in the range of 1 to 50 pF / cm ² (within the region 50), the luminous efficiency is 20 lm / W or more. It can be seen that can be obtained. 25 lm / W
To obtain a luminous efficiency exceeding 1 to 10 p
It is preferable to be within the range of F / cm ² (in the region 52).

When the lamp capacitance is increased, the luminous efficiency of the lamp decreases because the electron density in the discharge vessel 10 increases, so that the ionization probability of xenon atoms increases and the generated excimer This is considered to be because the probability that the molecule is broken before emitting light increases. That is, it is considered that the number of excimer molecules to be produced is out of the condition for maximizing the number.

In Table 2 and FIG. 2, when the lamp capacity is less than 1 pF / cm ² , the voltage drop in the dielectric layer 14 and the phosphor layer 15 becomes large, so that the starting voltage increases and the lighting is started. It is expected that this will be difficult. Further, when the lamp capacity exceeds 50 pF / cm ² , the voltage applied to the dielectric layer 14 or the phosphor layer 15 at the time of lighting exceeds the withstand voltage of the dielectric layer 14 or the phosphor layer 15, and as a result, It is expected that the dielectric layer 14 or the phosphor layer 15 will be destroyed.

Next, a method for manufacturing the lamp 100 will be exemplarily described.

First, a front glass substrate 11 and a rear glass substrate 12 made of translucent soda lime glass are prepared, and then the front glass substrate 11 and the rear glass substrate 12 are prepared.
An electrode 13 is formed on each of the surfaces. The electrodes 13 are formed by applying a conductive metal paste (for example, a silver paste manufactured by Tokuriki Honten Co., Ltd.) by screen printing using a desktop printer. Since the mesh portions of the desktop printing machine are patterned linearly at the same width and the same interval, the front glass substrate 11 and the rear glass substrate 12 are screen-printed by the desktop printing machine.
A linear (striped) electrode 13 can be applied thereon.

Next, after the front glass substrate 11 and the rear glass substrate 12 coated with the electrodes 13 are sufficiently dried, they are baked in a furnace at 500 to 600 ° C., so that the metal powder in the metal paste is melt-formed. Then, the electrode 13 is fixed to the front glass substrate 11 and the rear glass substrate 12 by firing and scattering the resin solvent.

Next, a dielectric layer 14 is formed on the surfaces of the front glass substrate 11 and the rear glass substrate 12 on which the electrodes 13 are formed.
To form The dielectric layer 14 is formed by uniformly applying a transparent dielectric paste (for example, a lead glass paste manufactured by Asahi Glass Co., Ltd.) on the surfaces of the front glass substrate 11 and the rear glass substrate 12 so as to cover the electrodes 13. This is done by printing. This printing can be performed using a desktop printing machine. Next, the dielectric paste is sufficiently dried and fired at an atmosphere temperature of 500 to 600 ° C., and then the dielectric powder in the dielectric paste is melt-formed into a film, and the resin solvent is fired and scattered. Thus, the dielectric layer 14 is fixed to the front glass substrate 11 and the rear glass substrate 12.

Next, the phosphor layer 15 is formed on the surface of the dielectric layer 14.
To form The formation of the phosphor layer 15 is performed in substantially the same manner as in the above steps. First, the phosphor for PDP is diluted with a small amount of a resin solvent such as α-terpionel and sufficiently stirred, and then the front glass substrate 11 on the side where the electrode 13 is formed is formed.
The printing is performed by printing on the surface of the rear glass substrate 12 with a desktop printer. As the mesh portion of the desktop printer, a mesh portion having a structure capable of uniformly coating the phosphor layer 15 on the surface of the dielectric layer 14 is used. Next, after sufficiently drying the front glass substrate 11 and the rear glass substrate 12 on which the phosphor layer 15 is printed, 400 to 500 ° C.
Then, the phosphor layer 15 is fixed to the surface of the dielectric layer 14 by baking and scattering the resin solvent.

Next, the discharge vessel 10 is formed from the front glass substrate 11 and the rear glass substrate 12 obtained through the above steps.

To form the discharge vessel 10, first, a glass substrate spacer 18 having a thickness of 0.55 mm is arranged on one back glass substrate 12. Glass substrate spacer 18
Are arranged around the phosphor layer 15. The glass substrate spacer 18 serves to fix the discharge gap length, and is made of soda lime glass. Then
Frit glass 17 (for example, manufactured by Asahi Glass Co., Ltd.) as a sealing material is dispersed with an organic solvent (for example, vehicle C manufactured by Tokyo Ohka Kogyo Co., Ltd.), and the frit glass paste is dispersed using a dispenser or the like. It is formed uniformly around the glass substrate spacer 18 on the substrate 12.

Next, bonding is performed with the front glass substrate 11 on which the electrodes 13, the dielectric layer 14, and the phosphor layer 15 are formed, and after this bonding, the front glass substrate 11 that is disposed to face each other is bonded. And the rear glass substrate 12 are firmly fixed with heat-resistant metal fittings. One of the two glass substrates is provided with a hole for gas exhaust and sealing,
An exhaust pipe 19 made of glass is connected to the portion using the sealing material described above.

Next, the discharge vessel 1 to which the exhaust pipe 19 is connected
0 at an atmosphere temperature of 450 ° C., thereby melting the lead glass powder in the frit glass paste,
Then, the resin solvent is fired and scattered. Thus, the front glass substrate 11 and the rear glass substrate 12 are sealed by the frit glass 17.

Finally, the exhaust pipe 19 connected to the sealed front glass substrate 11 is connected to a vacuum pump, and after exhausting impurity gases in an atmosphere of 350 ° C., the atmosphere is returned to room temperature, and is made of xenon alone. Noble gas 16 at 13.3 kPa
Enclose to a degree. Then, if you close the hole for the exhaust pipe 19,
A lamp 100 is obtained.

In this embodiment, as the front substrate 11 and the rear substrate 12, a glass substrate having a structure in which the electrode 13, the dielectric layer 14, and the phosphor layer 15 are formed in this order is used. However, a configuration in which the phosphor layer 15 is formed in a portion other than the front substrate 11 and the back substrate 12 or another layer (for example, a magnesium oxide layer) is provided between the dielectric layer 14 and the phosphor layer 15 The formed configuration is also applicable. Further, in the present embodiment, the sealed discharge vessel 1 using the glass substrates 11 and 12 facing each other is used.
Although an example of 0 has been described, the present invention is not limited to this example, and glass of another shape (for example, cylindrical shape) can be used.

Although glass was used as a substrate material for the front substrate 11 and the rear substrate 12, the present invention is not limited to this.
It is also possible to use other materials (for example, translucent ceramics). Further, an electrode 1 composed of silver
3, the electrode 13 is not limited to this, and an electrode 13 made of another metal (such as copper or iron) may be used.
A transparent electrode such as ITO may be used. Although an example in which lead glass is used as the dielectric layer 14 has been described, other dielectric materials, for example, glasses such as soda glass, and resins such as phenol resin, urea resin, and vinyl resin may be used. Is also possible.

In the present embodiment, a so-called three-wavelength band fluorescent lamp using a combination of three kinds of phosphors of a blue phosphor, a green phosphor and a red phosphor has been described as an example. However, the present invention is not limited to this. For example, the present invention can be applied to a two-wavelength or five-wavelength fluorescent lamp using other combinations. Further, the electrode 13, the dielectric layer 14, the phosphor layer 1
Although screen printing was used to form each of the glass substrates 5 on the glass substrates 11 and 12, other methods, such as vapor deposition, can be used. Note that xenon simple substance was used at 13.3 kPa as the rare gas to be sealed, but the present invention is not limited to this, and other gas pressures or other gases can be used. For example, at least one rare gas such as krypton, helium, or at least one rare gas
It is also possible to use a mixed gas obtained by mixing various kinds of halogens such as iodine and chlorine. The applied voltage is 20k
Although an example using a sine wave of Hz has been described, the present invention can be applied to other frequencies, and can be applied to other arbitrary waveforms such as a rectangular wave. Since the light emitting device of the present embodiment does not use mercury as a discharge gas,
It is environmentally friendly. (Embodiment 2) Embodiment 2 according to the present invention will be described with reference to FIG. In order to simplify the description of the present embodiment and an embodiment described later, points different from the first embodiment will be mainly described, and description of the same points as the first embodiment will be omitted or simplified.

FIG. 3 schematically shows the configuration of the lamp 200 of the present embodiment. The lamp 200 according to the present embodiment includes:
At least one of the front substrate 11 and the rear substrate 12 in the discharge vessel 10 is connected with a capacitor 30 in series.
The combined capacitance (Cf) and the second combined capacitance (Cb) are adjusted to be substantially equal. That is, Cf and Cb
The first combined capacitance (Cf) and the second combined capacitance (Cb) are substantially the same as in the lamp 100 according to the first embodiment also by the configuration using the capacitor 30 that adjusts substantially the same. Can be realized. (Embodiment 3) Embodiment 3 according to the present invention will be described with reference to FIG. FIG. 4 schematically shows a modification of the front substrate 11 of the first embodiment.

In the third embodiment, the total area of the electrodes 13a on the front substrate 11 is smaller than the total area of the electrodes 13b on the rear substrate 12 in order to increase the light extraction efficiency from the front substrate 11 side. It is configured as follows. further,
The electrode 13 is formed such that the ratio of the total area of the overlapping portion of the phosphor layer 15a and the electrode 13a to the area of the phosphor layer 15a formed on the front substrate 11 is in the range of 5% to 50%.
a is preferably formed. If the ratio of the area is less than 5%, when the electrode 13a has an electrode width having an appropriate resistance, the electrode interval becomes too large, and as a result, luminance unevenness occurs on the light emitting surface. Further, when the area ratio exceeds 50%, the probability that the light emitted from the phosphor layer 15 is absorbed or scattered by the electrode 13a increases, which causes a reduction in the total luminous flux. In order to more effectively prevent the luminance unevenness of the light emitting surface and the reduction of the total luminous flux, it is more preferable that the electrode 13a is configured so that the area ratio is 10 to 30%.

As shown in FIG. 5, the area of the phosphor layer 15b formed on the back substrate 12 is
The ratio of the total area of the overlapping portion of 5b and the electrode 13b is 5% to
It is preferable that the electrode 13b is configured to be 100%. FIG. 5 schematically shows a modification of the rear substrate 12 of the first embodiment. As with the reasons mentioned above,
When the area ratio is less than 5%, if the electrode 13b has an electrode width having an appropriate resistance, the interval between the electrodes 13b becomes too large, and luminance unevenness occurs on the light emitting surface. Further, in order to collect light traveling in the rear direction toward the front as viewed from the inside of the lamp (the interior of the discharge vessel 10), it is desirable that the ratio of the above-mentioned area is large.

Further, from the viewpoint of increasing the light extraction efficiency in the front direction, the electrode 13a on the front substrate 11 is
Preferably has a light-transmitting property. In addition, it is desirable that the light-transmitting electrode 13 be made of one or both of indium tin oxide and tin oxide from the viewpoints of low resistance and high visible light transmittance.

In the above embodiment, the electrode 13
Although a plurality of linear electrodes parallel to each other are used as (13a and 13b), the present invention is not limited thereto, and electrodes having other electrode shapes such as a mesh shape can be used. Also, the configuration for extracting light from the front glass substrate 11 has been described. However, when light is extracted from the rear glass substrate 12, the configuration of the electrodes 13 can be similarly implemented by exchanging the front glass substrate 11 and the rear glass substrate 12. It is. (Embodiment 4) Embodiment 4 according to the present invention will be described with reference to FIG. FIG. 6 schematically shows a modification of the front substrate 11 of the first embodiment. The configuration shown in FIG. 6 differs from the configuration of the first embodiment in the shape of the dielectric layer 14a. In FIG. 6, the phosphor layer 15a is omitted.

As shown in FIG. 6, in the present embodiment, the dielectric layer 14a on the front substrate 11 is formed in a region located between the electrodes 13a.
It has a portion 14a 'that is less than half the thickness of a. In this way, more visible light generated inside the lamp (inside the discharge vessel 10) can be extracted from the front glass substrate 11 to the outside. That is, in the structure of the light emitting device of the present embodiment, the dielectric layer 14a formed on the surface other than the surface of the electrode 13a is not related to the electric discharge. Absorption and scattering of visible light by the layer 14a can be suppressed, and as a result, more visible light can be extracted outside. Specifically, when the thickness of the portion 14a 'of the dielectric layer 14a is set to, for example, 50% or less of the thickness of the dielectric layer 14a located on the electrode 13a, light emission from the phosphor layer 15 is reduced. The probability of being absorbed or scattered by the front glass substrate 11 can be reduced, and as a result, the amount of visible light that can be extracted from the front glass substrate 11 can be increased, and the reduction of the total luminous flux due to the dielectric layer 14a can be suppressed. Can be.
In order to more effectively suppress the reduction of the total luminous flux, the electrode 13a
More preferably, the thickness of the portion 14a 'of the dielectric layer 14a is 0% to 20% with respect to the thickness of the dielectric layer 14a located thereon. The thickness of the portion 14a 'of 0% means that the dielectric layer 14a is not formed.

In this embodiment, a translucent dielectric is used as the dielectric layer 14. However, in the case where the dielectric layer 14 is not formed except for the surface of the electrode 13,
The dielectric layer 14 does not need to be translucent, and can be used for the dielectric 14 that does not transmit visible light. Also,
Although the configuration in which light is extracted from the front glass substrate 11 has been described, in the case of a configuration in which light is extracted from the rear glass substrate 12, the front glass substrate 11 having the configuration of the present embodiment is used.
May be used as the rear glass substrate 12.

The front glass substrate 11 having the dielectric layer 14a having the structure shown in FIG. 6 may be formed as follows.

First, a translucent dielectric paste (for example, lead glass paste manufactured by Asahi Glass Co., Ltd.) is uniformly printed on the surface of the front glass substrate 11 on which the electrodes 13a are formed, using a desktop printer. Next, after the printed front glass substrate 11 is sufficiently dried, the patterned electrode 1
A mesh mask having a pattern capable of sufficiently covering 3a is prepared, and printing is performed using a table printing machine in accordance with the pattern. Next, after the front glass substrate 11 is sufficiently dried, it is heated and fired at an atmosphere temperature of 500 to 600 ° C.
Next, melt-forming the dielectric powder in the dielectric paste,
The dielectric layer 14a is fixed to the front glass substrate 11 by firing and scattering the resin solvent.

As described above, the thickness of each dielectric layer 14a other than the surface of the electrode 13a or the surface of the electrode 13a is changed by adjusting the number of times of printing using the two types of printing patterns. be able to. The method of forming the dielectric layer 14b on the rear glass substrate 12 may be the same as in the first embodiment. Further, in the present embodiment, a plurality of linear electrodes parallel to each other are used as the electrodes 13a, but electrodes having other electrode shapes such as a mesh shape can also be used. Embodiment 5 Embodiment 5 according to the present invention will be described with reference to FIG. FIG. 7 schematically shows a modification of the rear substrate 12 of the first embodiment. The configuration shown in FIG. 7 differs from the configuration of the first embodiment in the shape of the phosphor layer 14b.

As shown in FIG. 7, in this embodiment, the phosphor layer 15 formed on the dielectric layer 14b of the back substrate 12 is formed.
b is a portion having a thickness of 5% or more and 95% or less with respect to the thickness of the phosphor layer 15b formed on the dielectric layer 14b located between the electrodes 13b in a region located above the electrode 13b. 15b '. This way,
The luminance of the phosphor layer 15b can be made uniform.
When the thickness of the portion 15b 'of the phosphor layer 15b is less than 5% or more than 95%, the difference between the luminance of the phosphor layer 15b' and the luminance of the other portions of the phosphor layer 15b is different. As a result, the luminance unevenness on the light emitting surface becomes remarkable, which is not preferable. In order to effectively suppress the luminance unevenness on the light emitting surface, the thickness of the portion 15b 'of the phosphor layer 15b is set to 20%.
More preferably, it is set to about 70%.

The back glass substrate 12 provided with the phosphor layer 15b having the structure shown in FIG. 7 may be formed as follows.

First, the phosphor for PDP is diluted with a resin solvent (for example, a small amount of α-terpionaire) and stirred sufficiently.
This phosphor is printed on the surface of the back glass substrate 12 on which the electrode 13b and the dielectric layer 14b are formed by a desktop printer. At this time, the mesh portion of the desktop printer has a structure that allows the phosphor to be uniformly applied to the surface of the dielectric layer 14b.

Next, after the back glass substrate 12 after the above-mentioned process is sufficiently dried, a mesh mask having a pattern applicable to a region excluding the surface of the dielectric layer 14b located on the patterned electrode 13b is formed. Prepare, then
Printing is performed according to the pattern by a desktop printing machine equipped with such a mesh mask. After that, 400-50
By heating and firing at an atmosphere temperature of 0 ° C., the resin solvent is fired and scattered, and the phosphor layer 15b is fixed to the surface of the dielectric layer 14b.

As described above, by adjusting the number of times of printing using each of the two types of printing patterns, the thickness of the portion 15b ′ of the phosphor layer 15b and the thickness of the phosphor layer 15b in the other portions are adjusted. Can be changed.
In the present embodiment, the configuration using the rear glass substrate 12 has been described. However, the present invention is similarly applicable to a configuration using the front glass substrate 11, or both the front glass substrate 11 and the rear glass substrate 12. The configuration of the front glass substrate 11 can be combined with the configuration of the fourth embodiment.

In this embodiment, the phosphor layer 15 is made of P
Although the example using the DP phosphor has been described, other luminescent materials that emit visible light when excited by ultraviolet light can also be used. Further, in the present embodiment, a plurality of linear electrodes parallel to each other are used as the electrodes 13b, but electrodes having other electrode shapes such as a mesh shape can also be used. In the present embodiment, screen printing is used as a method for forming the phosphor layer 15b on the back glass substrate 12, but
The method is not limited to this, and other methods can be used.

[0081]

According to the present invention, the first combined capacitance of the dielectric layer and the front phosphor layer on the front substrate and the second combined capacitance of the dielectric layer and the back phosphor layer on the rear substrate are provided. Since the capacitance is configured to be substantially equal, the positive and negative peak values of the lamp current can be appropriately controlled, and as a result, a light emitting device with improved luminous efficiency of the lamp can be provided. it can.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration of a light emitting device 100 according to a first embodiment.

FIG. 2 is a graph showing a relationship between luminous efficiency and lamp capacity of the lamp 100.

FIG. 3 is a diagram schematically illustrating a configuration of a light emitting device 200 according to a second embodiment.

FIG. 4 is a plan view schematically showing a configuration of a front substrate 11 according to a third embodiment.

FIG. 5 is a plan view schematically showing a configuration of a back substrate 12 according to a third embodiment.

FIG. 6 is a cross-sectional view schematically illustrating a configuration of a front substrate 11 according to a fourth embodiment.

FIG. 7 is a cross-sectional view schematically illustrating a configuration of a back substrate 12 according to a fifth embodiment.

FIG. 8 is a diagram schematically showing a configuration of a conventional light emitting device 1000.

FIG. 9A is a cross-sectional view showing a lamp 1000 having a configuration in which a phosphor layer 115a on the front side is removed, and FIG.
3 is a graph showing the relationship between the relative luminance (%) and the thickness of the back phosphor layer (μm) in the configuration of FIG.

FIG. 10 is a diagram schematically showing an enlarged phosphor layer 115;

FIG. 11A is a cross-sectional view of the lamp 1000;
(B) is an equivalent circuit of (a).

FIG. 12 shows a lamp voltage (200
5 is a graph showing a relationship between V / div) and a lamp current (10 mA / div).

FIG. 13 is a diagram for explaining a light emission process of xenon in a vacuum ultraviolet region.

[Explanation of symbols]

 Reference Signs List 10 discharge vessel 11 front substrate (front glass substrate) 12 rear substrate (back glass substrate) 13 electrode 14 dielectric layer 15 phosphor layer (light emitting layer) 16 rare gas (sealing gas) 17 frit glass 18 glass substrate spacer 19 exhaust Tube 20 Lamp lighting power supply 30 Capacitor 100 Light emitting device (flat fluorescent lamp) 110 Discharge vessel 111 Front glass substrate 112 Back glass substrate 113 Electrode 114 Dielectric layer 115 Phosphor layer 116 Rare gas (sealing gas) 117 Frit glass 118 Glass Substrate spacer 1000 Light emitting device (flat fluorescent lamp)

Continuing on the front page (72) Inventor Kawasaki Mitsuharu 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Makoto Inohara 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5C043 AA02 BB04 CD19

Claims (8)

[Claims] A closed gas discharge vessel comprising a light-transmitting front substrate, a rear substrate disposed opposite to the front substrate, a rare gas sealed in the discharge container, An electrode formed on the inner surface of each of the front substrate and the rear substrate, to which an alternating voltage is applied; and a dielectric layer formed on the inner surface of each of the front substrate and the rear substrate so as to cover the electrode A light emitting device comprising: a phosphor layer formed on the dielectric layer; a first capacitance of the front phosphor layer located on the dielectric layer on the front substrate; A second capacitance that is different from a second capacitance of a rear phosphor layer located on the dielectric layer on the rear substrate, and a first capacitance of the dielectric layer and the front phosphor layer that are on the front substrate. The combined capacitance and the A light emitting device, wherein the dielectric layer and the back phosphor layer have substantially the same second combined capacitance. 2. A value obtained by dividing a smaller one of the first combined capacitance and the second combined capacitance by a larger one of the first combined capacitance and the second combined capacitance is not more than 1 and not less than 0.86. The light emitting device according to claim 1, wherein: 3. The capacitance of the entire lamp defined by the first combined capacitance and the second combined capacitance is 1 pF /
The light emitting device according to claim 1, wherein the light emitting device has a cm ^{2 to} 50 pF / cm ² . 4. The dielectric constant of the front phosphor layer and the dielectric constant of the back phosphor layer are equal, and the thickness of the front phosphor layer is smaller than the thickness of the back phosphor layer. The light-emitting device according to claim 1, wherein the light-emitting device is a light-emitting device. 5. At least one of the front substrate and the rear substrate is connected in series to a capacitor that adjusts the first combined capacitance and the second combined capacitance substantially equal. Item 5. The light emitting device according to any one of Items 1 to 4. 6. The electrode is a plurality of linear electrodes or mesh electrodes parallel to each other, and a total area of the electrodes on the front substrate is smaller than a total area of the electrodes on the rear substrate. The light emitting device according to claim 1. 7. The electrode is a plurality of linear electrodes or mesh electrodes parallel to each other, and the dielectric layer on the front substrate is located on the electrode in a region located between the electrodes. 5 of dielectric layer thickness
7. The method according to claim 1, wherein said portion has a portion of 0% or less and 0% or more.
The light-emitting device according to any one of the above. 8. The electrode may be a plurality of linear electrodes or mesh electrodes parallel to each other, and the phosphor layer formed on the dielectric layer may be formed in a region located above the electrode. 8. The device according to claim 1, further comprising a portion having a thickness of 5% or more and 95% or less with respect to the thickness of the phosphor layer formed on the dielectric layer located between the electrodes. A light-emitting device according to any one of the above.