GB2302207A - Display flourescent lamp and display device - Google Patents

Display flourescent lamp and display device Download PDF

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Publication number
GB2302207A
GB2302207A GB9524416A GB9524416A GB2302207A GB 2302207 A GB2302207 A GB 2302207A GB 9524416 A GB9524416 A GB 9524416A GB 9524416 A GB9524416 A GB 9524416A GB 2302207 A GB2302207 A GB 2302207A
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GB
United Kingdom
Prior art keywords
diameter portion
light emitting
fluorescent lamp
display
cylindrical container
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9524416A
Other versions
GB9524416D0 (en
Inventor
Hironobu Kawaguchi
Noriyuki Tomimatsu
Kazuo Yoshioka
Sadayuki Matsumoto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP14630895A external-priority patent/JP3116775B2/en
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Publication of GB9524416D0 publication Critical patent/GB9524416D0/en
Publication of GB2302207A publication Critical patent/GB2302207A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • G09F9/313—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being gas discharge devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/025—Associated optical elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H01J61/302—Vessels; Containers characterised by the material of the vessel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H01J61/32—Special longitudinal shape, e.g. for advertising purposes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/38—Devices for influencing the colour or wavelength of the light
    • H01J61/42—Devices for influencing the colour or wavelength of the light by transforming the wavelength of the light by luminescence
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/52—Cooling arrangements; Heating arrangements; Means for circulating gas or vapour within the discharge space
    • H01J61/523—Heating or cooling particular parts of the lamp
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
    • H01J61/76—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a filling of permanent gas or gases only
    • H01J61/78—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a filling of permanent gas or gases only with cold cathode; with cathode heated only by discharge, e.g. high-tension lamp for advertising
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/95—Lamps with control electrode for varying intensity or wavelength of the light, e.g. for producing modulated light
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
    • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
    • H01J65/042—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field
    • H01J65/046—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field the field being produced by using capacitive means around the vessel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/38—Devices for influencing the colour or wavelength of the light
    • H01J61/40—Devices for influencing the colour or wavelength of the light by light filters; by coloured coatings in or on the envelope

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)

Abstract

A display fluorescent lamp comprises a dielectric cylindrical container 2 having a large-diameter portion 2a in which rare gas is sealed and a small-diameter portion 2b which is substantially coaxial with and connected to the large-diameter portion 2a. The lamp includes an optically transmissive light emitting potion 8, an internal electrode 3, a fluorescent substance layer 7 formed on the inside face of the large-diameter portion 2a, and an external electrode 4 formed on the outside face of the large-diameter portion. The fluorescent substance layer 7 extends up to and perhaps beyond the joint between the small-diameter portion 2b and the large-diameter portion 2a of the cylindrical container 2. Therefore, a uniform fluorescent substance layer 7 can be formed even if the diameter of the container is made small. The light emitting portion 8 may be modified, e.g. by shaped protrusions or by wavelength selective transmissive materials, to reduce the luminance of the lamp when it is not energised. To control the relative brightness of red, blue and green emitting lamp in a display, the external electrodes 4 may be of different lengths.

Description

DISPLAY FLUORESCENT LAMP AND DISPLAY DEVICE The present invention relates to a display fluorescent lamp used as a light emitting device for use in, for example, a large image display unit or an electric sign board, and further relates to a display device.
Figs. 16 and 17 are a perspective view partially broken away of, and a sectional view of a prior art display fluorescent lamp disclosed in, for example, Japanese Patent Publication (Kokai) No. 5-190152. In the drawings, reference numeral 1 means a display fluorescent lamp, 2 is a cylindrical glass valve forming the display fluorescent lamp 1, and 3 is an internal electrode inserted into the glass valve 2 through a lower end surface of the glass valve 2. Further, reference numeral 4 means an external electrode mounted on an outer surface of the glass valve 2, 7 is a fluorescent substance layer formed on inner walls of a side surface and the lower end surface of the glass valve 2, and 8 is a light emitting portion having permeability mounted onto an upper end surface of the glass valve 2.A power source 6 is connected between the internal electrode 3 and the external electrode 4 via lead wires 5a and 5b.
A description will now be given of the operation.
When the power source 6 applies ac voltage across the internal electrode 3 and the external electrode 4, the voltage is applied to a rare gas in the glass valve 2 through glass serving as dielectric material, thereby causing discharge. Ultraviolet rays are generated by the discharge to excite the fluorescent substance layer 7, and are thereafter converted into specific visible rays which are determined depending upon the fluorescent substance.
Since the fluorescent substance itself is a white body, the visible rays emitted from the fluorescent substance are substantially totally reflected off the fluorescent substance layer 7 mounted on the inner wall of the glass valve 2, and are thereafter sent back into the glass valve 2. The visible rays can be outputted and emitted out of the glass valve 2 through the light emitting portion 8 exclusively having permeability. Thus, the display fluorescent lamp 1 serves as a light emitting device having high luminance.
The conventional display fluorescent lamp can serve as the light emitting device in a large image display unit to provide suitable emission with high luminance. However, with higher resolution of the large image display unit, it is necessary to reduce the diameter of the glass valve 2 for higher density arrangement of the display fluorescent lamps 1. Hence, a distance between the internal electrode 3 and the external electrode 4 is more reduced, resulting in problems in that, for example, a sufficient creepage distance can not be ensured for electrical insulation.
Accordingly, it is an object of the present invention to provide a display fluorescent lamp in which a fluorescent substance layer can be formed uniformly.
It is another object of the present invention to provide a display fluorescent lamp capable of suppressing power consumption.
It is a further object of the present invention to provide a display fluorescent lamp having high luminance.
It is a still further object of the present invention to provide a display fluorescent lamp in which the insulation distance between the internal electrode and the external electrode can be increased without enlarging the external shape of the display fluorescent lamp.
A further object of the present invention is to provide a display fluorescent lamp in which the light emitting area can be increased.
A still further object of the present invention is to provide a display fluorescent lamp in which the cylindrical container can be formed easily.
A still further object of the present invention is to provide a display fluorescent lamp in which the light emitting portion is made of soda lime glass and the cylindrical portion is made of lead glass to facilitate fusion of the light emitting portion and the cylindrical portion.
A still further object of the present invention is to provide a display fluorescent lamp capable of reducing an increase of luminance at a time when the lamp is not lighting due to reflection on the fluorescent substance layer even when a flat shape light emitting portion is used.
A still further object of the present invention is to provide a display fluorescent lamp capable of reducing an increase of luminance at a time when the lamp is not lighting even if a flat shape light emitting portion is used, by providing constant transmittance in the entire range of visible rays.
A still further object of the present invention is to provide a display fluorescent lamp in which an increase of luminance at a time when the lamp is not lighting can be reduced by utilizing a transmittance characteristic corresponding to the wavelength of visible rays even when a flat shape light emitting portion is used.
A still further object of the present invention is to provide a display fluorescent lamp in which an increase of luminance at a time when the lamp is not lighting can be reduced by suppressing reflection of external light on the flat shape light emitting portion with fine semi spherical protrusions.
A still further object of the present invention is to provide a display fluorescent lamp in which an increase of luminance at a time when the lamp is not lighting can be reduced by suppressing reflection of external light on the flat shape light emitting portion with semicylindrical protrusions.
A still further object of the present invention is to provide a display fluorescent lamp in which stable discharge controlling is achieved.
A still further object of the present invention is to provide a display fluorescent lamp capable of preventing light emission of the fluorescent substance which is caused by discharge at a second external electrode.
A still further object of the present invention is to provide a display fluorescent lamp capable of suppressing power consumption by discharge at the second external electrode.
A still further object of the present invention is to provide a display device in which the ratio of luminance of red, green and blue is controlled.
In accordance with a first aspect of the present invention, there is provided a display fluorescent lamp comprising; a dielectric cylindrical container having a large-diameter portion in which rare gas is sealed and a small-diameter portion which is almost coaxially connected with the large-diameter portion at one end of the largediameter portion, the outside diameter thereof being smaller than that of the large-diameter portion; a light emitting portion which is formed at another end of the large-diameter portion and has permeability; an internal electrode which is inserted into the cylindrical container from the other end of the small-diameter portion which is not connected with the large-diameter portion; a fluorescent substance layer formed on the inside face excluding that in which the light emitting, portion is formed, of the large-diameter portion of the cylindrical container; and an external electrode formed on the outside face of the large-diameter portion excluding a portion in which the light emitting portion of the cylindrical container is formed, the fluorescent substance layer being disposed to extend up to a joint between the small-diameter portion and the large-diameter portion of the cylindrical container. Consequently, the fluorescent substance layer disposed to extend up to the joint between the smalldiameter portion and the large-diameter portion of the display fluorescent lamp makes it possible to form uniform fluorescent substance layer.
According to another preferred embodiment of the present invention, the external electrode is formed so as to be shorter than the length of the large-diameter portion in the axial direction, of the cylindrical container.
Consequently, it is possible to reduce power consumption.
According to still another preferred embodiment of the present invention, the external electrode is formed in the vicinity of the lower end of the cylindrical container which is opposite the light emitting portion formed on the end face of the large-diameter portion of the cylindrical container. Consequently, it is possible to obtain high luminance.
According to a further preferred embodiment of the present invention, folds are provided on the small-diameter portion in which the external electrode is located, in order to enlarge the creepage distance. The folds improve dielectric strength without changing the size of the display fluorescent lamp.
According to a still further preferred embodiment of the present invention, the light emitting portion is formed in a flat shape. The flat shaped light emitting portion provides the wide light emitting area.
According to a still further preferred embodiment of the present invention, the flat shaped light emitting portion is formed with a material different from that of which the cylindrical portion of the cylindrical container is made, and the cylindrical portion is formed of a dielectric having a higher softening point than that of the dielectric constituting the cylindrical portion. The dielectric having a higher softening point than that of the dielectric constituting the cylindrical portion facilitates forming of the cylindrical container.
According to a still further preferred embodiment of the present invention, a dielectric constituting the flat shaped light emitting portion is formed of soda-lime glass and the dielectric constituting the cylindrical portion is formed of lead glass. Consequently, it is possible to facilitate fusion between the light emitting portion and the cylindrical portion.
According to a still further preferred embodiment of the present invention, the dielectric constituting the flat shaped light emitting portion is formed so as to have a wavelength selecting transmittance or a transmittance depending on the wavelength of light incident on the dielectric. Consequently, it is possible to reduce an increase of luminance at a time when the lamp is not lighting due to reflection on the fluorescent substance layer.
According to a still further preferred embodiment of the present invention, the dielectric constituting the flat shaped light emitting portion is formed as a neutral density filter. The neutral density filter has a constant transmittance in the entire range of visible light to reduce an increase of luminance of the fluorescent substance at a time when the lamp is not lighting.
According to a still further preferred embodiment of the present invention, the dielectric constituting the flat shaped light emitting portion is formed as a color filter.
The color filter has a transmittance depending on the wavelength of visible light emitted by the fluorescent substance to reduce an increase of luminance at a time when the lamp is not lighting due to reflection on the fluorescent substance.
According to a still further preferred embodiment of the present invention, a plurality of fine semispherical protrusions are formed on the outside face of the flat shaped light emitting portion. The plurality of fine semi spherical protrusions reduce an increase of luminance when the lamp is not lighting by hindering reflection of external light.
According to a still further preferred embodiment of the present invention, a plurality of semicylindrical protrusions are formed concentrically on the outside face of the flat shaped light emitting portion. The semicylindrical protrusions disposed concentrically reduce an increase of luminance at a time when the lamp is not lighting by hindering reflection of external light on the light emitting portion.
According to a still further preferred embodiment of the present invention, a second external electrode is formed on the outside face of the small-diameter portion of the cylindrical container. The second external electrode stabilizes control of discharge.
According to a still further preferred embodiment of the present invention, a second external electrode is disposed on the small-diameter portion of the cylindrical container so as not to overlap the fluorescent substance layer extended up to the joint between the small-diameter portion and the large-diameter portion of the cylindrical container. Consequently, it is possible to suppress light emission of the fluorescent substance due to discharge at the second external electrode, thereby reducing an increase of luminance at a time when the lamp is not lighting.
According to a still further preferred embodiment of the present invention, a portion of the internal electrode which is opposite the second external electrode is coated with dielectric. Coating of dielectric reduces power consumption due to discharge at the second external electrode.
In accordance with a second aspect of the present invention, there is provided a display device comprising a plurality of fluorescent lamps, arranged in a line or on a plane, each of which is one of at least three types of fluorescent lamps, i.e., a red emission lamp, a green emission lamp or a blue emission lamp, each of the fluorescent lamps including; a dielectric cylindrical container having a large-diameter portion in which rare gas is sealed and a small-diameter portion which is almost coaxially connected with the large-diameter portion at one end of the large-diameter portion, the outside diameter thereof being smaller than that of the large-diameter portion; a light emitting portion which is formed at another end of the large-diameter portion and has permeability; an internal electrode which is inserted into the cylindrical container from the other end of the smalldiameter portion which is not connected with the largediameter portion; a fluorescent substance layer formed on the inside face excluding that in which the light emitting portion is formed, of the large-diameter portion of the cylindrical container; and an external electrode formed on the outside face of the large-diameter portion excluding a portion in which the light emitting portion of the cylindrical container is formed, the external electrodes of the fluorescent lamps including at least a red emission lamp, a green emission lamp and a blue emission lamp being formed so that the lengths thereof differ from each other according to the difference in colors of rays of light emitted by the fluorescent lamps.Consequently, it is possible to control the ratio of the brightness of the red emission lamps, the green emission lamps and the blue emission lamps.
Further objects and advantage of the present invention will be made evident from the following description of the preferred embodiments thereof illustrated in the accompanying drawings.
Fig. 1 is a sectional view showing one embodiment of a display fluorescent lamp according to the present invention; Fig. 2 is a sectional view showing another embodiment of the display fluorescent lamp according to the present invention; Fig. 3 is a graph showing a relationship between the length of the external electrode and power consumption.
Fig. 4 is a graph showing a relationship between the length of the external electrode and emission luminance.
Fig. 5 is a sectional view showing still another embodiment of the display fluorescent lamp according to the present invention; Fig. 6 is a graph showing a relationship between the position of the external electrode and emission luminance.
Fig. 7 is a sectional view showing still another embodiment of the display fluorescent lamp according to the present invention; Fig. 8 is a sectional view showing still another embodiment of the display fluorescent lamp according to the present invention; Fig. 9 is a view showing light emission in a case in which the light emitting portion is semispherical.
Fig. 10 is a view showing light emission in a case in which the light emitting portion is flat.
Fig. 11 is a sectional view showing still another embodiment of the display fluorescent lamp according to the present invention.
Fig. 12 is a sectional view showing still another embodiment of the display fluorescent lamp according to the present invention.
Fig. 13 is a sectional view showing still another embodiment of the display fluorescent lamp according to the present invention.
Fig. 14 is a sectional view showing still another embodiment of the display fluorescent lamp according to the present invention.
Fig. 15 is a diagram showing an effect in a case in which a portion of the internal electrode which is opposite the external electrode is coated with glass.
Fig. 16 is a perspective view partially broken away of a prior art display fluorescent lamp; and Fig. 17 is a sectional view showing the prior art display fluorescent lamp of Fig. 16.
Fig. 1 is a longitudinal sectional view of a display fluorescent lamp according to an embodiment of the present invention. In the figure, reference numeral 1 means a display fluorescent lamp, and 2 is a cylindrical container forming the display fluorescent lamp 1, that is, a glass valve serving as a cylindrical container including portions having different diameters in an axial direction. Further, reference numeral 2a means a large diameter portion of the glass valve 2, and 2b is a small diameter portion of the glass valve 2.
Reference numeral 3 means an internal electrode inserted into the glass valve 2 through an end surface portion of the glass valve 2 on the side of the small diameter portion 2b, 4 is an external electrode disposed on an outer surface of the large diameter portion 2a of the glass valve 2, and 7 is a fluorescent substance layer formed on an internal side surface and an internal lower end surface of the large diameter portion 2a of the glass valve 2.
Reference numeral 8 means a light emitting portion having permeability, disposed at the upper end (i.e., at the left end in the drawing) of the large diameter portion 2a of the glass valve 2. The internal electrode 3 and the external electrode 4 are connected to a power source 6 via lead wires 5a and 5b.
A description will now be given of the operation.
When voltage is applied by the power source 6 between the internal electrode 3 and the external electrode 4, the voltage is applied to rare gas in the display fluorescent lamp 1 through glass serving as a dielectric material, resulting in discharge. Ultraviolet rays generated by the discharge excite the fluorescent substance layer 7, and are converted into specific visible light determined depending upon fluorescent substances.
Since the fluorescent substance itself serves as a white body, the visible light emitted from the fluorescent substance are substantially totally reflected off the fluorescent substance layer 7 which is formed on the inner surface of the glass valve 2 on the side of the large diameter portion 2a. Thereafter, the visible light are sent back into the glass valve 2, and are finally outputted and emitted out of the glass valve 2 through the light emitting portion 8 having permeability.
The voltage applied between the internal electrode 3 and the external electrode 4 is in an approximate range of 200 to 2000 V while varying depending upon a type of the sealed rare gas or sealing pressure. For example, when the glass valve 2 has the large diameter portion 2a having diameter of 6.45 mm, and xenon is sealed as the rare gas at pressure of 200 Torr, it is necessary to apply voltage of about 600 V or more. In this case, an insulation distance of 5.6 mm or more is required as the creepage distance between the internal electrode and the external electrode if IEC380 standard is applied.
In the aforementioned conventional display fluorescent lamp, it is impossible to extend the creepage distance between the internal electrode and the external electrode to be half the diameter of the glass valve or more.
Therefore, the glass valve having diameter of 6.45 mm provides an insufficient creepage distance of about 3 mm.
On the other hand, in the display fluorescent lamp 1 of the present invention, when the glass valve 2 has the large diameter portion 2a having a diameter of 6.45 mm and the small diameter portion 2b having a diameter of 2.4 mm, it is possible to provide a creepage distance of about 6 mm or more by setting the length of the small diameter portion 2b to about 4 mm or more.
Further, the applied voltage may exceed the above voltage depending upon the type of the sealed rare gas, the sealing pressure, and so forth. In such a case, it is also possible to provide a required creepage distance and sufficiently ensure electrical insulation between the internal electrode 3 and the external electrode 4 by appropriately setting the length of the small diameter portion 2b.
The external electrode 4 can efficiently and easily be formed by printing conductive paste on the outer surface of the glass valve 2 by using a printing method such as screen printing.
In the display fluorescent lamp 1 of this embodiment, the fluorescent substance layer 7 extends onto the small diameter portion 2b of the glass valve 2. In such a structure, highly accurate control on controlling the formation of the fluorescent substance layer 7 at a border portion between the large-diameter portion 2a and the small-diameter portion 2b is not required, so that a uniform fluorescent substance layer can be formed easily.
Reference numeral 99 designates "fold" or "wrinkle" provided on the external face of the small-diameter portion to extend the creepage distance. It is permissible to dispose a plurality of folds and further, as shown in Fig.
1, it is permissible to form the folds with a material different from that of which the small-diameter portion is made and attach them to the small-diameter portion.
Fig. 2 is a longitudinal sectional view showing still another embodiment of the display fluorescent lamp according to the present invention. In the display fluorescent lamp 1 of the embodiment, the external electrode 4 is shorter than the large-diameter portion 2a of the glass valve 2 in the axial direction. In measuring power consumed in the display fluorescent lamp 1 with the length of the external electrode 4 set as a parameter, power consumption increases with the length of the external electrode 4. Fig. 3 shows an example of this phenomenon.
Thus, if the length of the external electrode 4 is determined to be the same as the length of the largediameter of the glass valve 2 in the axial direction as in the conventional example, excessive power is consumed. On the contrary, if the length of the external electrode 4 is determined to be shorter than the length of the largediameter portion 2a of the glass valve 2 in the axial direction, it is possible to keep the power consumption of the display fluorescent lamp 1 on an appropriate value.
Fig. 4 shows the result of measurement of the emission luminance of the display fluorescent lamp 1 with the length of the external electrode 4 set as a parameter. As shown in Fig. 4, it is made evident that the emission luminance of the display fluorescent lamp 1 increases with the length of the external electrode 4. On the other hand, when a color display device is constructed by combining a red emission lamp, a green emission lamp and a blue emission lamp, an appropriate luminance ratio is needed in the emission luminance of the red emission lamp, the green emission lamp and the blue emission lamp with respect to a problem about the reproduction of colors.As a means for realizing this, it can be considered to differentiate the values of voltages to be applied between the internal electrode 3 and the external electrode 4 with respect to the red emission lamp, the green emission lamp and the blue emission lamp. For this purpose, it is necessary to prepare a plurality of types of power supplies. If the lengths of the external electrodes 4 of the display fluorescent lamps 1 used as the red emission lamp, the green emission lamp and the blue emission lamp are made different from each other using the characteristic shown in Fig. 4, the emission luminance of the display fluorescent lamp 1 used as the red emission lamp, the green emission lamp and the blue emission lamp can be adjusted easily, thereby realizing a required luminance ratio easily.
Fig. 5 is a longitudinal sectional view of the display fluorescent lamp according to still another embodiment of the present invention. In the display fluorescent lamp according to this embodiment, the external electrode 4 which is shorter than the length in the axial direction of the large-diameter portion 2a of the glass valve 2 is formed in the vicinity of the lower end of the largediameter portion 2a of the glass valve 2. If the length of the external electrode 4 is set to be shorter than the length in the axial direction of the large-diameter portion 2a of the glass valve 2, it becomes to be a problem where the external electrode 4 is located in the large-diameter portion 2a of the glass valve 2. Thus, with the external electrode 4 forming position as a parameter, the emission luminance of the display fluorescent lamp 1 is measured.
As a result, the result shown in Fig. 6 is obtained.
Namely, it is testified that the emission luminance of the display fluorescent lamp 1 can be kept high by forming the external electrode 4 in the vicinity of the lower end of the large-diameter 2a of the glass valve 2. This can be considered to be because light emission of the fluorescent substance layer formed on the lower end contributes largely to the emission luminance of the display fluorescent lamp 1. Thus, it is possible to obtain a display fluorescent lamp having high luminance by forming the external electrode 4 in the vicinity of the lower end of the largediameter portion 2a of the glass valve 2.
Fig. 7 is a longitudinal sectional view of the display fluorescent lamp according to still another embodiment of the present invention. In the display fluorescent lamp of this embodiment, the external electrode 4 extends to a part of the small-diameter portion 2b of the glass valve 2. In accordance with this embodiment, it is possible to provide a sufficient space required to connect the lead wire 5b with the external electrode 4 within an extended cylindrical surface of the large diameter portion 2a of the glass valve 2. Therefore, the connecting portion for the lead wire 5b does not require an unnecessarily large outside diameter, resulting in high density arrangement of the display fluorescent lamps 1.
Fig. 8 is a longitudinal sectional view of the display fluorescent lamp according to still another embodiment of the present invention. In the display fluorescent lamp of this embodiment, the light emitting portion 8 of the glass valve 2 is formed in a flat shape. If the light emitting portion 8 is semispherical, light generated from the fluorescent substance layer formed at the lower end of the large-diameter portion 2a of the glass valve 2, which contributes largely to the emission luminance of the display fluorescent lamp 1, is emitted from the front face of the light emitting portion 8 of the display fluorescent lamp 1 through an area smaller than the internal diameter area of the large-diameter portion 2a of the glass valve 2, as shown in Fig. 9, because of the concave lens effect of the light emitting portion 8.On the other hand, when the light emitting portion 8 is in a plan shape, as shown in Fig. 10, light generated from the fluorescent substance layer formed on the lower end of the large-diameter portion 2a of the glass valve 2 can be emitted from the front face of the display fluorescent lamp 1 through its generating area or the internal diameter area of the large-diameter portion 2a of the glass valve 2. Therefore, by forming the light emitting portion 8 in a plan shape, it is possible to enlarge the light emitting area viewed from the front side of the display fluorescent lamp 1. In Figs. 9 and 10, influences of the small-diameter portion 2b is neglected from the viewpoint of convenience of simulation.
Further, by forming the flat shaped light emitting portion 8 with a material different from that of which the large-diameter portion 2a of the glass valve 2 is made so as to have a higher softening point than that of glass used for the large-diameter portion 2a of the glass valve 2, it is possible to form the glass valve 2 easily.
As an example, by forming the light emitting portion 8 with soda-lime glass and the large-diameter portion 2a of the glass valve 2 with lead glass, it is possible to facilitate fusion of the light emitting portion 8 and the large-diameter portion 2a of the glass valve 2.
When external light enters the glass valve 2 through the light emitting portion 8, it is reflected by the fluorescent substance layer 7 and then goes out through the light emitting portion 8, thereby increasing luminance at a time when the lamp is not lighting. By forming the light emitting portion 8 of the glass valve 2 with glass having a wavelength selecting transmittance characteristics, i.e., a transmittance characteristics depending on the wavelength of light incident on the glass, the external light is filtered twice to reduce the strength thereof when the light enters into and goes out of the glass valve 2, with the result that such the increase of luminance at a time when the lamp is not lighting can be reduced and hence high contrast displayed images can be obtained.
The aforementioned light emitting portion 8 having the wavelength selecting transmittance characteristics may be constructed with a neutral density filter having a constant transmittance in the entire range of visible light. In this case, by providing such a constant transmittance characteristic in the entire range of visible light, it is possible to reduce an increase of luminance at a time when the lamp is not lighting caused by reflection by the fluorescent substance. Further, it is permissible to construct the light emitting portion 8 with a color filter having a transmittance characteristic in accordance with the wavelength of visible light generated by the fluorescent substance, thereby improving contrast.
Fig. 11 is a longitudinal sectional view of the display fluorescent lamp according to still another embodiment of the present invention. In the display fluorescent lamp of this embodiment, a plurality of small sized semi spherical protrusions 8a are provided on the external face of the light emitting portion 8. According to this embodiment, by scattering external light which enters the light emitting portion 8 by means of small sized semispherical protrusions 8a, it is possible to prevent the external light from entering through the flat shaped light emitting portion 8.
Fig. 12 is a longitudinal sectional view of the display fluorescent lamp according to still another embodiment of the present invention. In the display fluorescent lamp of this embodiment, a plurality of semicylindrical protrusions 8b are provided concentrically on the external face of the light emitting portion 8. In this case also, it is possible to prevent external light from entering through the flat shaped light emitting portion 8.
Fig. 13 is a longitudinal sectional view of the display fluorescent lamp according to still another embodiment of the present invention. In the display fluorescent lamp of this embodiment, a second external electrode 12 is disposed on the external face of the smalldiameter portion 2b of the glass valve 2. In this case, by space charge generated by discharge (auxiliary discharge) caused by applying voltage between the internal electrode 3 and the second external electrode 12, it is possible to generate discharge (main discharge) between the internal electrode 3 and the external electrode 4 easily.
Generally, a voltage necessary for starting discharge is a function of the product pd of gas pressure p of space discharge and the gap length d of the discharge space according to Paschen's law, and it is well known that the voltage reaches the minimum value when the pd is a particular value. Ordinarily, in the discharge lamp, the product pd is set so as to exceed the product pd which gives this minimum value. When gas pressure is specified, the voltage necessary for starting discharge increases with increases in the gap length.
Thus, the discharge between the internal electrode 3 and the external electrode 4 needs a higher voltage for starting discharge as compared to discharge between the internal electrode 3 and the second external electrode 12.
Thus, there may be cases where even if a voltage for generating discharge is applied between the internal electrode 3 and the second external electrode 12, no discharge occurs between the internal electrode 3 and the external electrode 4. On the other hand, when a particular voltage necessary for starting discharge between the internal electrode 3 and the external electrode 4 is applied between the internal electrode 3 and the external electrode 4, it is possible to start stabilized discharge with a voltage lower than when no space charge exists, by means of space charge generated by the auxiliary discharge.
As for a position in which the second external electrode 12 is located, by disposing the second external electrode 12 at a position which is located on the smalldiameter portion 2b of the glass valve 2 so as not to overlap the fluorescent substance layer, as shown in Fig.
13, it is possible to prevent light emission of the display fluorescent lamp 1 due to discharge between the internal electrode 3 and the second external electrode 12.
Fig. 14 is a longitudinal sectional view of the display fluorescent lamp according to still another embodiment of the present invention. In the display fluorescent lamp of this embodiment, glass coating 13 is formed on a portion of the internal electrode 3, which is opposite the second external electrode 12. In this case, it is possible to reduce power consumption by the auxiliary discharge as shown in Fig. 15.
As a conclusion of the above description, the present invention has the advantages which will be described below.
According to a preferred embodiment of the present invention, because the fluorescent substance layer is disposed to extend up to the joint between the smalldiameter portion and the large-diameter portion of the cylindrical container, uniform fluorescent substance layer can be formed.
According to another preferred embodiment of the present invention, because the external electrode is formed so as to be shorter than the length of the large-diameter portion in the axial direction, of the cylindrical container, it is possible to reduce power consumption.
According to still another preferred embodiment of the present invention, because the external electrode is formed in the vicinity of the lower end face which is opposite the light emitting portion formed on the large-diameter portion of the cylindrical container, it is possible to obtain high luminance.
According to a further preferred embodiment of the present invention, the creepage distance between the internal electrode and the external electrode can be ensured so as to be large without enlarging the fluorescent lamp.
According to a still further preferred embodiment of the present invention, because the light emitting portion is formed in a flat shape, it is possible to increase the light emitting area.
According to a still further preferred embodiment of the present invention, because the flat shaped light emitting portion is formed with a material different from that of which the cylindrical portion of the cylindrical container is made, and the cylindrical portion is formed of a dielectric having a higher softening point than the dielectric constituting the cylindrical portion, it is possible to form the cylindrical container easily.
According to a still further preferred embodiment of the present invention, because the dielectric constituting the flat shaped light emitting portion is formed of soda glass and the dielectric constituting the cylindrical portion is formed of lead glass, it is possible to facilitate fusion between the light emitting portion and the cylindrical portion.
According to a still further preferred embodiment of the present invention, because the dielectric constituting the flat shaped light emitting portion is formed so as to have a wavelength selecting transmittance characteristics, i.e., a transmittance characteristics depending on the wavelength of light incident on the dielectric, it is possible to reduce an increase of luminance at a time when the lamp is not lighting due to reflection on the fluorescent substance layer when the flat shaped light emitting portion is used also.
According to a still further preferred embodiment of the present invention, because the dielectric constituting the flat shaped light emitting portion is formed as a neutral density filter, it is possible to reduce an increase of luminance at a time when the lamp is not lighting by providing a constant transmittance in the entire range of visible light even if the flat shaped light emitting portion is used.
According to a still further preferred embodiment of the present invention, because the dielectric constituting the flat shaped light emitting portion is formed as a color filter, it is possible to reduce an increase of luminance at a time when the lamp is not lighting by using a transmittance characteristic depending on the wavelength of visible light even if the flat shaped light emitting portion is used.
According to a still further preferred embodiment of the present invention, because a plurality of fine semi spherical protrusions are formed on the outside face of the flat shaped light emitting portion, it is possible to reduce an increase of luminance at a time when the lamp is not lighting by hindering reflection of external light on the flat shaped light emitting portion by means of the fine semispherical protrusions.
According to a still further preferred embodiment of the present invention, because a plurality of semicylindrical protrusions which are formed concentrically on the outside face of the flat shaped light emitting portion, it is possible to reduce an increase of luminance at a time when the lamp is not lighting by hindering reflection of external light on the flat shaped light emitting portion by means of the semicylindrical protrusions.
According to a still further preferred embodiment of the present invention, because a second external electrode is formed on the outside face of the small-diameter portion of the cylindrical container, it is possible to control discharge stably.
According to a still further preferred embodiment of the present invention, because the second external electrode is disposed on the small-diameter portion of the cylindrical container so as not to overlap the fluorescent substance layer extended up to the joint between the largediameter portion and the small-diameter portion of the cylindrical container, it is possible to suppress light emission of the fluorescent substance due to discharge by the second external electrode.
According to a still further preferred embodiment of the present invention, because a portion of the internal electrode which is opposite the second external electrode is coated with dielectric, it is possible to suppress power consumption due to discharge by the second external electrode.
According to a still further preferred embodiment of the present invention, because the external electrodes are formed so that the lengths thereof differ from each other according to colors of rays of light emitted by the red emission lamp, the green emission lamp and the blue emission lamp, it is possible to control the brightness of the red emission lamps, the green emission lamps and the blue emission lamps easily.
It is to be understood that changes and variations may be made without departing from the spirit or scope of the present invention. The present invention is not restricted to particular aspects thereof except those specified in the attached claims.

Claims (18)

1. A display fluorescent lamp comprising a dielectric cylindrical container having a large-diameter portion in which rare gas is sealed and a small-diameter portion which is substantially coaxial with and connected to an end of said large-diameter portion, the outside diameter of the small-diameter portion being smaller than that of said large-diameter portion, a light emitting portion provided at the other end of said large-diameter portion and being optically transmissive, an internal electrode which is inserted into said cylindrical container from the end of said small-diameter portion which is not connected with said large-diameter portion, a fluorescent substance layer formed on the inside face of the large-diameter portion of said cylindrical container excluding the part thereof forming the light emitting portion, and an external electrode formed on the outer face of said large-diameter portion excluding the part thereof forming the light emitting portion, wherein said fluorescent substance layer extends up to the smalldiameter portion of said cylindrical container.
2. The display fluorescent lamp according to claim 1, characterized in that said external electrode is shorter than the length of the large-diameter portion of said cylindrical container in the axial direction.
3. The display fluorescent lamp according to claim 2, characterized in that said external electrode is formed in the vicinity of an end face of said cylindrical container which is opposite another end face of said cylindrical container on which said light emitting portion is formed.
4. The display fluorescent lamp according to claim 1, characterized in that an outside face of said smalldiameter portion has a fold or wrinkle for increasing a creepage distance between said internal electrode and said external electrode.
5. The display fluorescent lamp according to claim 1, characterized in that said light emitting portion has partially a flat portion.
6. The display fluorescent lamp according to claim 5, characterized in that said light emitting portion is formed of dielectric having a softening point higher than a softening point of dielectric constituting a cylindrical portion of said cylindrical container.
7. The display fluorescent lamp according to claim 6, characterized in that dielectric constituting said light emitting portion is formed of soda-lime glass, and dielectric constituting the cylindrical portion is formed of lead glass.
8. The display fluorescent lamp according to claim 5, characterized in that said light emitting portion is made of dielectric having a transmittance characteristics depending on the wavelength of light incident thereon.
9. The display fluorescent lamp according to claim 8, characterized in that the dielectric constituting said light emitting portion has characteristics of a neutral density filter.
10. The display fluorescent lamp according to claim 8, characterized in that the dielectric constituting said light emitting portion has characteristics of a color filter.
11. The display fluorescent lamp according to claim 5, characterized in that a plurality of fine semi spherical protrusions are formed on an outside face of said light emitting portion.
12. The display fluorescent lamp according to claim 5, characterized in that a plurality of semicylindrical protrusions are formed on an outside face of said light emitting portion.
13. The display fluorescent lamp according to claim 1, characterized in that a second external electrode is formed on an outside face of the small-diameter portion of said cylindrical container.
14. The display fluorescent lamp according to claim 13, characterized in that said fluorescent substance layer is disposed so as to extend up to the small-diameter of said cylindrical container, and said second external electrode is located so as not to overlap said fluorescent substance layer.
15. The display fluorescent lamp according to claim 13, wherein a portion of said internal electrode which is opposite said second external electrode is coated with dielectric.
16. A display device comprising a plurality of fluorescent lamps, arranged in a line or on a plane, each of which is one of at least three types of fluorescent lamps, i.e., a red emission lamp, a green emission lamp or a blue emission lamp, each of the fluorescent lamps comprising a dielectric cylindrical container having a large-diameter portion in which rare gas is sealed and a small-diameter portion which is almost coaxially connected with said large-diameter portion at one end of said largediameter portion, the outside diameter thereof being smaller than that of said large-diameter portion, a light emitting portion which is formed at another end of said large-diameter portion and has permeability, an internal electrode which is inserted into said cylindrical container from the other end of said small-diameter portion which is not connected with said large-diameter portion, a fluorescent substance layer formed on the inside face excluding that in which said light emitting portion is formed, of said large-diameter portion of said cylindrical container, and an external electrode formed on the outside face of said large-diameter portion excluding a portion in which said light emitting portion of said cylindrical container is formed, said plurality of display fluorescent lamps being disposed adjacently in a linear or plane shape, characterized in that the lengths of the external electrodes of the plural fluorescent lamps including at least a red emission lamp, a green emission lamp and a blue emission lamp differ from each other according to the difference in colors of lights emitted out of the fluorescent lamps.
17. A display fluorescent lamp substantially as hereinbefore described with reference to any one of Figures 1 to 15 of the accompanying drawings.
18. A display device substantially as hereinbefore described with reference to any one of Figures 1 to 15 of the accompanying drawings.
GB9524416A 1995-06-13 1995-11-29 Display flourescent lamp and display device Withdrawn GB2302207A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP14630895A JP3116775B2 (en) 1994-07-21 1995-06-13 Display fluorescent lamp and display element

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GB9524416D0 GB9524416D0 (en) 1996-01-31
GB2302207A true GB2302207A (en) 1997-01-08

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2312983A (en) * 1996-05-08 1997-11-12 Mitsubishi Electric Corp Fluorescent lamp display
GB2322220A (en) * 1996-05-08 1998-08-19 Mitsubishi Electric Corp Fluorescent lamp display

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05190152A (en) * 1992-01-10 1993-07-30 Mitsubishi Electric Corp Fluorescent lamp for display

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05190152A (en) * 1992-01-10 1993-07-30 Mitsubishi Electric Corp Fluorescent lamp for display

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Patents Abstracts of Japan, vol 17, no 608 (E-1457) & JP050190152A (Mitsubishi) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2312983A (en) * 1996-05-08 1997-11-12 Mitsubishi Electric Corp Fluorescent lamp display
GB2322220A (en) * 1996-05-08 1998-08-19 Mitsubishi Electric Corp Fluorescent lamp display
US5818175A (en) * 1996-05-08 1998-10-06 Mitsubishi Denki Kabushiki Kaisha Gas discharge image display
GB2322220B (en) * 1996-05-08 1999-02-17 Mitsubishi Electric Corp Gas discharge image display
GB2312983B (en) * 1996-05-08 1999-02-17 Mitsubishi Electric Corp Gas discharge image display

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