JPH11149905A - Cold cathode tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold cathode tube having low brightness and good stability and prevented form deterioration of rising up property. SOLUTION: Both ends of a glass tube of this cold cathode tube 1 are sealed with electrodes 4a, 4b and R, G, B phosphors 3 mixed with 35% of calcium pyrophosphate 8 working as a non-luminescence agent and as a binder are stuck to the inner wall of the glass tube and an inert gas Ar(argon) 6 and mercury 7 are sealed in the inside of the tube. Electric discharge is started by applying high voltage between the electrodes 4a, 4b to generate a ultraviolet ray with 253.7 nm wavelength in the inside of the tube and excite the phosphors 3. The phosphors 3 emit visible light with 23,000 cd/m<2> brightness at 80% light quantity within about 15 sec and stably emit light at 100% light quantity after about 45 sec. The reading-out property of an image pickup element (CCD) of a scanner having the lamp as a light source is corresponding to 80% or higher light quantity at 23,000 cd/m<2> light source brightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold-cathode tube having a low luminance and a stable luminance so that the rise of the luminance does not drop.

[0002]

2. Description of the Related Art It has been known that a cold cathode tube is used for a device requiring a light source, for example, a backlight of a liquid crystal display device. In a cold cathode tube used for such a liquid crystal display device or the like, a fluorescent substance is applied to the inner wall of an elongated glass tube, and an inert gas (Ar
Etc.) and mercury. Then, a high voltage is applied between the electrodes at both ends of the glass tube from a power supply via external lead wires to start discharge, and the vaporized mercury is excited by collisions with electrons and atoms of a sealing gas to emit ultraviolet rays. (Mainly at a wavelength of 253.7 nm). The ultraviolet light excites the phosphor, and is converted into an emission color (visible light wavelength) depending on the material and composition of the phosphor. Thereby, the cold-cathode tube emits visible light.

[0003] By the way, the phosphor coated in the glass tube is mixed with a particulate substance such as calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) or barium calcium borate (hereinafter referred to as borate). I have. The purpose of mixing the particulate calcium pyrophosphate with the phosphor is
This is for binding the respective phosphor powders that emit R, G, and B visible light to each other, and calcium pyrophosphate is used as a binding agent therefor. The purpose of mixing the borate with the phosphor is to adhere the phosphor that emits visible light bound by calcium pyrophosphate to the inner wall of the glass tube.

Assuming that the total coating amount per unit area of the phosphor, calcium pyrophosphate and borate which emits visible light adhered and coated in the glass tube is 100%, calcium pyrophosphate and borate are used. The content of
About 1% is necessary and sufficient for each.

[0005]

However, when the above-mentioned cold-cathode tube is used as a light source for a device that requires a light source with reduced luminance and a short rise time of luminance, for example, a reading device such as a scanner, CCD, which is the image sensor of the reading device, because the light intensity of the cold cathode tube is too large
However, there is a problem that the exposure becomes excessive.

[0006] In order to solve this problem, several techniques have been considered for lowering the brightness of the cold cathode fluorescent lamp. For example, there is a method of lowering the luminance by lowering the value of the current (tube current) flowing through the cold-cathode tube. Therefore, there is a problem that the reading device cannot be operated immediately. Therefore, it was conceived that the cold-cathode tubes were always lit even when not in use.However, this wasted power consumption, overworked the cold-cathode tubes, and shortened the service life of the cold-cathode tubes. There was a problem that would.

It has also been considered to reduce the amount of the fluorescent material applied to the cold cathode tube. However, when the amount of the fluorescent material applied is reduced, there is a problem that the luminance decreases but the luminance becomes unstable.

[0008] The object of the present invention is to solve the above-mentioned conventional situation,
An object of the present invention is to provide a cold-cathode tube in which the luminance is low and the luminance is stable without lowering the rise of the luminance.

[0009]

The structure of the cold cathode tube of the present invention will be described below. First, the cold-cathode tube according to the first aspect of the present invention emits electrons into the cold-cathode tube when a voltage is applied, and collides the electrons with the encapsulant previously sealed in the cold-cathode tube to generate ultraviolet rays. At least one pair of electrodes provided on the cold cathode tube, a plurality of luminous bodies that are applied to the cold cathode tube and emit visible light when the ultraviolet rays collide and are excited, and are mixed with the plurality of luminous bodies. A non-light-emitting body that binds the light-emitting bodies together and is applied to the cold-cathode tube together with the plurality of light-emitting bodies and does not emit light even when the ultraviolet light collides; a mixing ratio including the light-emitting body and the non-light-emitting body 10 whole
In the case of 0%, the content ratio α of the non-luminous body is set to 5 ≦ α <
It is configured as 100%.

Next, the cold-cathode tube according to the second aspect of the present invention
A cold cathode tube applied to an apparatus requiring a light source,
When a voltage is applied, at least one pair of electrodes used for the cold-cathode tube to emit electrons into the cold-cathode tube and collide the electrons with an encapsulant previously sealed in the cold-cathode tube to generate ultraviolet rays And a plurality of luminous bodies that are applied to the cold cathode tube and emit visible light when the ultraviolet rays collide and are excited, and are mixed with the plurality of luminous bodies, and are applied to the cold cathode tube together with the plurality of luminous bodies. A light-emitting member that emits light at a wavelength deviated from the wavelength required by the device when the ultraviolet light collides and is excited to be excited, and the total mixing ratio including the light-emitting body and the light-emitting member is 100%. In this case, the content ratio α of the light emitting member is set to 5 ≦ α <100%.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a cross-sectional view schematically showing a configuration of a cold cathode tube according to an embodiment, and FIG. 1B is a partially enlarged view of the inside of the tube. Figures (a), (b)
In the cold cathode tube 1 shown in FIG. 1, a fluorescent substance 3 is applied to the inner wall of an elongated glass tube 2, and electrodes 4a and 4b are provided at both ends of the glass tube 2.
Are arranged and the inside is sealed. Electrodes 4a and 4b
, External lead wires 5a and 5b are drawn out, and an inert gas 6 and mercury 7 are sealed in the glass tube 2 whose inside is sealed by the electrodes 4a and 4b.

For the electrodes 4a and 4b, Fe-Ni (iron nickel) having a relatively large work function is used as a material. As the phosphor 3, a plurality of phosphor fine particles 3-1 emitting R (red) visible light, a plurality of phosphor fine particles 3-2 emitting G (green) visible light, and B
A plurality of phosphor fine particles that emit visible light (blue) 3-
In this case, calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) 8 and borate 9 are added to the powder of the fine particles 3-1, 3-2, and 3-3 of the plurality of phosphors 3. Are mixed to form the coating material 10.

As described above, the calcium pyrophosphate 8 has a function of a binder, and a plurality of kinds of fine particles 3-1 and 3-2 of a plurality of phosphors 3 for emitting R, G, and B light, and
The powder of 3-3 is bound to each other. The calcium pyrophosphate 8 also has a function of lowering the luminance of the phosphor 3 according to the content thereof, which will be described later in detail.

The borate 9 has a function of bonding the R, G, and B phosphors 3 bound by the calcium pyrophosphate 8 to the inner wall of the glass tube 2 as described above.
The inert gas 6 is Ar (argon) or the like.

The cold cathode tube 1 starts discharging when a high voltage is applied between the electrodes 4a and 4b at both ends of the glass tube 2 from the power supply 11 via the external leads 5a and 5b. The mercury vaporized inside by this discharge is excited by collisions with electrons and atoms of a sealed gas, and mainly has a wavelength of 2 nm.
Generate 53.7 nm UV light. The ultraviolet light excites the phosphor 3 and is converted into light having a wavelength in the visible light range depending on the material and composition of the phosphor 3. Thereby, the cold cathode tube 1 emits visible light. At this time, from outside the cold cathode tube 1, R,
The light emitted from each of the phosphors G and B is mixed and becomes visible as white light.

Next, the manufacturing process of the cold cathode tube 1 will be described. First, a cylindrical glass tube 2 is prepared. The dimensions of the glass tube 2 are, for example, 120 mm in length and 2.2 mm in diameter. In addition, each has a particle size of about 5
R, G, B phosphor 3 microparticles 3 μm (micron)
A coating material 10 is prepared by mixing 1, 3, 2 and 3-3, calcium pyrophosphate 8 having a particle diameter of about 1 μm, and borate 9 having a particle diameter of about 1 μm in a mixing ratio described later in detail. R, G, and B phosphors 3-1 described above;
3-2 and 3-3 are excited by collision with ultraviolet light, and the wavelength of the light emitted thereby is changed to R phosphor partial particles 3-
1 is 658 nm, and G phosphor fine particles 3-2 are 54 nm.
4 nm, and 453 nm for the phosphor fine particles 3-3 of B
Is set to be

After applying the coating material 10 to the inner wall of the glass tube 2 with a thickness of 15 to 20 μm, heat of 550 ° C. or more is applied to the glass tube 2. By this heating, the coating material 1
The R, G, and B phosphor fine particles 3-1, 3-2, and 3-3 in FIG. 0 are bound by the calcium pyrophosphate 8 and adhered to the inner wall of the glass tube 2 by the borate 9.
Then, Fe-Ni (iron nickel) is applied to both ends of the glass tube 2.
After the electrodes 4a and 4b are attached and the inside of the glass tube 2 is evacuated, an inert gas 6 and mercury 7 are sealed in the vacuum tube. Further, lead wires 5a and 5b are attached to the electrodes 4a and 4b, respectively, so as to be connectable to the power supply 11.

FIG. 2A is a side sectional view schematically showing a configuration of a main part of a scanner 15 which is a color image reading apparatus provided with the above-mentioned cold cathode tube 1, and FIG. FIG. 2 is a perspective view schematically showing the internal structure. As shown in FIGS. 7A and 7B, the scanner 15 includes a main body case 16 and an elongated reflector 17 having a U-shaped cross section is provided near one end (the left end in the figure) inside the main body case 16. The opening 17-1 is disposed at a predetermined distance from the paper surface in the direction perpendicular to the paper surface of the color document 19 in FIG. Then, the cold cathode tube 1 is arranged in the reflector 17 as a light source. Further, a circuit board 27 for driving the cold cathode tube 1 as a light source is disposed in the main body case 16.

An original reading opening 18 is formed at the bottom of the main body case 16 located in front of the U-shaped opening 17-1 of the reflection plate 17. Then, the cold cathode fluorescent lamp 1 as a light source of the scanner 15 is caused to emit light, and the main body case 16 of the scanner 15 is moved rightward on the original surface of the color original 19 as shown by an arrow A in the figure. Is reflected by the reflector 17 and the opening 17-1 of the reflector 17 is formed.
And is radiated to the moving color document 19 through the document reading port 18.

A part of the light applied to the color document 19 is reflected from the document reading port 18 into the main body case 16. A reflecting mirror 21 is disposed obliquely on the optical path reflected in the main body case 16,
The light reflected from the main body case 16 is reflected by the reflecting mirror 21 and changes its course in the horizontal direction as indicated by an alternate long and short dash line arrow B in FIGS. The light passes through the rotary filter 22 disposed on the course and is separated.

The rotary filters 22 each have a fan-shaped R shape.
(Red) color separation filter 22R, G (green) color separation filter 22G, and B (blue) color separation filter 22
The filters of the three colors B are sequentially connected and integrally form a disk, and the center thereof is supported by the tip of the rotating shaft of the motor 23 and driven to rotate. The light transmitted through the rotary filter 22 and condensed is converged by a condenser lens 24 disposed on the optical path, and forms an image on an image sensor (CCD) 25 disposed on the downstream side of the optical path. .

The above-mentioned rotary filter 22 includes an image sensor 25
It is driven in rotation in synchronization with the reading speed of
The color separation filters on the optical path are sequentially 22R, 22G, 22
B, and switches the image on the color original 19 to R, G, B
Into three colors. The image sensor 25 reads the image formed into the three colors of R, G, and B for each line, and reads the read color image information through a code 26 provided in the scanner 15. Output to a printer or personal computer not shown.

In the present embodiment, the image pickup device (CCD) 25 has a light source luminance of 23000 cd / m ^2.
If the light amount of 80% or more of the stable light amount is output from the light source, the reading correction can be performed. The light source luminance of 23000 cd / m ² is a value lower than the normal luminance of a normal cold-cathode tube, and
Conventionally, the current value of the tube current applied to the cold-cathode tube is reduced and the brightness is reduced.For this reason, until the cold-cathode tube of the scanner rises to the effective brightness, it takes seconds As described above, the rise time of the luminance becomes the rise time of the luminance in minutes.

However, in the cold cathode tube 1 according to the present embodiment, the luminance can be reduced without lowering the tube current value, and the rise of the luminance can be prevented from being lowered. It is the cold cathode tube 1 in the present embodiment.
This is because the configuration is such that the luminance of the stable light amount when the light emission driving is performed with a normal tube current is suppressed to a low level, that is, the luminance of the light source according to the reading characteristics of the CCD 25 is set to 23000 cd / m ² . Therefore, light emission can be driven by a normal tube current, and effective luminance can be obtained in a short time (80% or more of a stable light intensity of 23000 cd / m ² ).
Can be started up. Hereinafter, the configuration of the cold cathode tube 1 according to the present embodiment having such luminance characteristics will be further described.

FIG. 3 shows fine particles 3 of R, G, and B phosphors 3 constituting a coating material 10 applied in the cold cathode tube 1.
It is a chart which shows the mixing ratio of 1, 3-2 and 3-3, calcium pyrophosphate 8, and borate 9. In the figure, the names of the mixed materials “B phosphor”, “G phosphor”, “R phosphor”, “borate” and “calcium pyrophosphate” are shown in the leftmost column, and The chemical formula corresponding to the material is shown, the chemical name of each phosphor is shown in the next column, and the entire mixing ratio of the coating material 10 is 100% in the rightmost column.
The mixing ratio of each mixed material is expressed in%. As shown in the figure, the chemical formula of the B phosphor is “(SrCaBa”
_{) 5 (PO4) 3 Cl:} Eu ", the chemical name is" europium-activated halophosphate strontium B phosphor, calcium, barium ", the mixing ratio of B phosphor is 17%.
Further, as shown in the figure, the chemical formula of the G phosphor is “La P
O ₄ : Ce, Tb ”, and the chemical name of the G phosphor is“ cerium,
The mixing ratio of “terbium-activated lanthanum phosphate” and the G phosphor is 20%. The chemical formula of the R phosphor is “3.5 Mg
O.0.5 Mg F ₂ .Ge O ₂ : Mn ”, the chemical name of the R phosphor is“ manganese-activated magnesium fluorogermanate ”, and the mixing ratio of the R phosphor is 18%. The chemical formula of the borate is “(0.3CaO · 0.7BaO) · 1.
6B ₂ O _3), "chemical name" barium borate calcium borate ", the mixing ratio of the borate is 10%. The chemical formula of calcium pyrophosphate is “Ca ₂ P
The chemical name of ₂ O ₇ and calcium pyrophosphate is also “calcium pyrophosphate”, and the mixing ratio of the calcium pyrophosphate is 35%. The reason why the mixing ratio (content) of calcium pyrophosphate is set to 35% as described above in the ratio of each mixed material of the coating material 10 will be described below.

FIG. 4 is a characteristic diagram showing the relationship between the content of calcium pyrophosphate 8 in the coating material 10 applied in the cold cathode tube 1 and the brightness of the cold cathode tube. In the figure, the vertical axis indicates luminance (unit: cd / m ² ), and the horizontal axis indicates the content of calcium pyrophosphate 8. In the present embodiment, the luminance of the light source is set to 23000 cd / m ² as the optimal light amount in consideration of the sensitivity characteristic of the CCD 25 mounted on the scanner 15.

FIG. 3 shows various cold-cathode tubes prepared by applying coating materials with various contents of calcium pyrophosphate and applying the same to the inside of the tubes. The tube current of each is set to 4 to 5 mA. FIG. 6 is a characteristic diagram obtained by applying a tube current under normal conditions of a voltage of 300 V and a room temperature of 25 ° C. As shown in the figure, when the content of calcium pyrophosphate is less than 5%, the luminance of the cold cathode fluorescent lamp is 40,000.
cd / m ² and is maintained at an extremely high luminance. This luminance starts to decrease when the content of calcium pyrophosphate becomes 5% or more. Then, when the content of calcium pyrophosphate is 35%, the sensitivity characteristic of the CCD 25 becomes the luminance of 23000 cd / m ² required as the light source luminance. Hereinafter, the luminance further decreases as the content of calcium pyrophosphate increases.

As shown in FIG. 3 described above, the content of calcium pyrophosphate 8 in the coating material 10 of the cold cathode tube 1 in this embodiment is set to 35% from the experimental results shown in FIG. Things. As a result, a cold-cathode tube having a stable light intensity of 23000 cd / m ² can be obtained.

FIG. 5 is a diagram showing the rising characteristics (solid line C) of the brightness of the cold cathode tube 1 prepared by containing 35% of calcium pyrophosphate 8 in the coating material 10 as described above. FIG. 3 also shows, for comparison, luminance characteristics (dashed line D) when a conventional high-luminance cold-cathode tube is driven with a low tube current. In this embodiment, the driving conditions of the cold cathode tube 1 are the same as those for applying a normal tube current, that is, the tube current is 4 to 5 mA, the voltage is 300 V, and the room temperature is 2.
5 ° C. The conditions for driving the conventional high-brightness cold-cathode tube with a low tube current are as follows: the tube current is 3 mA, the voltage is 300 V, and the room temperature is 25 ° C.

As shown by the solid line C in the characteristic diagram of FIG. 3, the cold cathode fluorescent lamp 1 has a luminance of 80% and a rise time of 15 seconds.
(Seconds) and reaches the effective luminance without deteriorating the luminance rising characteristics. Further, after 45 seconds (after 60 seconds from the start of the luminance), the luminance reaches 100%, and thereafter, the luminance is maintained at 100% without change. On the other hand, in the case of the broken line D in which the conventional high-brightness cold-cathode tube is driven with a low tube current, the time until the rise of the brightness is 100 sec or more. In such a case, a person can usually wait without annoyance. Well over time. Therefore, in the method of lowering the tube current, it takes too much time to raise the luminance. However, in the cold cathode fluorescent lamp 1 according to the present embodiment, it is possible to lower the luminance without lowering the tube current value and to lower the rise of the luminance. No excellent properties are found.

In the above example, the sensitivity of the image pickup device (CCD) used in the scanner 15 is set to 2300 cd / m ² as the stable light amount of the cold-cathode tube 1 as a light source. Although the content α of calcium pyrophosphate is 35% (α = 35%), the content α is not limited to this, and may be changed according to the sensitivity of the imaging device (CCD). That is, the content of calcium pyrophosphate α
From 5% to less than 100% (5 ≦
The stable light amount of the cold-cathode tube as the light source can be set to a predetermined value by arbitrarily changing it within the range of α <100%).

In addition, calcium pyrophosphate is used as a substance (non-luminous substance) which is not excited even by the collision of ultraviolet rays and does not emit light. However, the present invention is not limited to this, and other non-luminous substances (non-luminous substance) may be used. Good. In addition, a light-emitting member that emits light of a wavelength that is not recognized by the imaging device (CCD) (wavelength shifted from the wavelength required by the device), for example, a light-emitting member such as a UV phosphor, is not limited to a substance that does not emit light. If so, the light emitting member may be mixed instead of the non-light emitting body. In this case, the other non-light emitting body or the light emitting body of the wavelength shifted from the wavelength required by the device is R,
In the case where the substance does not have a binding function of the G and B phosphors, for example, calcium pyrophosphate may be mixed as a binder separately. Calcium pyrophosphate exhibits a binding function with a mixing ratio of only 1% as described above.

The cold cathode tube is filled with an inert gas such as argon or mercury, but is not limited to this, and is made of a material that generates ultraviolet rays as a result of discharge by applying a voltage to an electrode provided in the cold cathode tube. If so, other materials may be used.

As the coating material 10, calcium pyrophosphate and borate are mixed with R, G, B phosphor fine particle powder, but not limited thereto, and R, G, B phosphor powder is used. May be mixed only with calcium pyrophosphate, and a borate may be used only between the mixture and the inner wall of the glass tube.

Although the scanner is connected to the printer or the personal computer by a cord as an independent device, the scanner may not be a separate scanner from the host device but may be, for example, an integrated scanner with the printer. The power source of the scanner may be any method such as a rechargeable battery, a commercially available battery, or a home power source via an A / C adapter, and the configuration of the power source is not limited.

In the above-described embodiment, the materials of the chemical formulas shown in FIG. 3 are used as the R, G, and B phosphors. However, the present invention is not limited to this, and other materials may be used. For example, as the B phosphor, the chemical formula “Srs (PO ₄ ) ₃ Cl: Eu” is used.
(Chemical name, strontium halophosphate activated by eurobium) or a material having a chemical formula of “Ba Mg ₂ Al ₁₆ O ₂₇ : Eu” (chemical name, barium aluminate, magnesium, eurobium) may be used. Further, as the R phosphor, a material such as chemical formula “Y ₂ O ₃ : Eu” (chemical name, eurobium-activated yttrium oxide) may be used.

The shape of the cold cathode tube is not limited to a cylindrical shape, but may be any shape. In addition, the cold cathode tube is used as the light source for the scanner, but the present invention is not limited to this and can be applied to any device that requires a light source.

In the above embodiment, the rotation filter 2
2 and the scanner 1
5, the light entering the main body case 16 is dispersed and focused on the image sensor 25 through the condenser lens 24. However, the present invention is not limited to this, and the light entering the main body case can be dispersed. Any other method may be used.

[0039]

As described above in detail, according to the present invention, a non-luminous body is arbitrarily mixed with a luminous body on the inner wall of a cold cathode tube within a predetermined mixing ratio range to reduce the stable light amount of the cold cathode tube. Since it is set arbitrarily, it is not necessary to adopt a method of applying a low tube current to obtain a low luminance, so that a normal tube current is applied so that the rising of the luminance does not drop and the luminance is low. It is possible to provide a stable cathode tube.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view schematically showing a configuration of a cold-cathode tube according to an embodiment, and FIG. 1B is a partially enlarged view of the inside of the tube.

FIG. 2A is a side sectional view schematically showing a configuration of a main part of a scanner provided with a cold cathode tube according to the embodiment, and FIG.
FIG. 2 is a perspective view schematically showing the internal structure.

FIG. 3 is a table showing a mixing ratio of each material constituting an application material applied in a cold cathode tube according to the embodiment.

FIG. 4 is a characteristic diagram showing the relationship between the content of calcium pyrophosphate in the coating material applied to the inside of the cold cathode tube in this embodiment and the brightness of the cold cathode tube.

FIG. 5 is a diagram showing a rising characteristic (solid line C) of luminance of the cold cathode fluorescent lamp according to the embodiment.

[Description of Signs] 1 Cold cathode tube 2 Glass tube 3 Phosphor 3-1 R phosphor fine particles 3-2 G phosphor fine particles 3-3 B phosphor fine particles 4a, 4b Electrodes 5a, 5b Lead Line 6 Inert gas 7 Mercury 8 Calcium pyrophosphate 9 Borate 10 Coating material 11 Power supply 15 Scanner 16 Body case 17 Reflector 17-1 Opening 18 Reading port 19 Color document 21 Reflector 22 Rotating filter 22R For R (red) Color separation filter 22G color separation filter for G (green) 22B color separation filter for B (blue) 23 motor 24 condenser lens 25 imaging device (CCD) 26 code 27 circuit board

Claims (2)

[Claims] When a voltage is applied, electrons are emitted into a cold-cathode tube, and the electrons collide with an encapsulant previously sealed in the cold-cathode tube to generate ultraviolet rays. A pair of electrodes, a plurality of luminous bodies that are applied to the cold cathode tubes, emit the visible light when the ultraviolet rays collide and are excited, and are mixed with the plurality of luminous bodies to bind the luminous bodies together to form the cold. A non-light-emitting body that is applied to the cathode tube together with the plurality of light-emitting bodies and does not emit light even when the ultraviolet light collides with the light-emitting body;
00%, the content ratio α of the non-luminous body is set to 5 ≦ α
A cold cathode tube characterized by <100%. 2. A cold-cathode tube applied to an apparatus requiring a light source, wherein when a voltage is applied, electrons are emitted into the cold-cathode tube and the electrons are previously sealed in the cold-cathode tube. At least a pair of electrodes provided on the cold cathode tube to generate ultraviolet rays by colliding with, a plurality of luminous bodies that are applied to the cold cathode tube, emit the visible light when the ultraviolet rays collide and are excited, A light emitting member mixed with the plurality of light emitters, applied to the cold cathode tube together with the plurality of light emitters, and emitted by a wavelength different from the wavelength required by the apparatus when the ultraviolet light is excited and excited. And the entire mixture ratio including the luminous body and the luminous member is 1
00%, the content ratio α of the light emitting member is 5 ≦ α
A cold cathode tube characterized by <100%.