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EP0948030A2 - Edelgasgefüllte Entladungslampe, Leuchtschaltung und Leuchtvorrichtung - Google Patents

Edelgasgefüllte Entladungslampe, Leuchtschaltung und Leuchtvorrichtung Download PDF

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Publication number
EP0948030A2
EP0948030A2 EP99302495A EP99302495A EP0948030A2 EP 0948030 A2 EP0948030 A2 EP 0948030A2 EP 99302495 A EP99302495 A EP 99302495A EP 99302495 A EP99302495 A EP 99302495A EP 0948030 A2 EP0948030 A2 EP 0948030A2
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EP
European Patent Office
Prior art keywords
vessel
discharge
lamp
rare
discharge lamp
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Withdrawn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
EP99302495A
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English (en)
French (fr)
Other versions
EP0948030A3 (de
Inventor
Teiji Shimokawa
Akio Watanabe
Kunio Yuasa
Kiyoshi Nishimura
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.)
Toshiba Lighting and Technology Corp
Original Assignee
Toshiba Lighting and Technology 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 JP21395598A external-priority patent/JPH11345692A/ja
Application filed by Toshiba Lighting and Technology Corp filed Critical Toshiba Lighting and Technology Corp
Publication of EP0948030A2 publication Critical patent/EP0948030A2/de
Publication of EP0948030A3 publication Critical patent/EP0948030A3/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
    • 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

Definitions

  • the present invention relates in general to fluorescent lamps and to methods of operating them. More particularly, the invention pertains to rare gas discharge lamps, their structural configurations and to methods of operating them.
  • Discharge lamps using mercury had become popular because of their operational characteristics. However, due to environmental concerns, there have been efforts to make discharge lamps without mercury. This has presented design challenges.. Now there are rare gas discharge lamps which use rare gases, such as the xenon, as a discharge medium enclosed within a transparent discharge vessel. Such lamps can be made to have a reasonable luminous flux stand up characteristic at low temperature. However, rare gas discharge lamps having only internal electrodes generally do not have sufficient luminescence for many uses.
  • Rare gas discharge lamps can be made with one or more external electrodes. By using at least one electrode positioned along the longer side of the external surface of the transparent discharge vessel, the amount of luminescence can be increased. Such lamp arrangements are particularly suitable for reading.
  • external electrode lamps have various structural and operational problems. They must be operated at a high voltage, typically 5 kV or greater. There is excessive ozone and other radiation and they make too much noise. They are often structurally weak where them is insulation between electrodes.
  • the discharge is stabilized and it is hard to produce the flickering of the discharge, and even when the service power is large, the radiation efficiency of present invention of the ultraviolet ray is good, and It aims at providing the rare gaseous discharge lamp equipped with the external electrode with which the optical output is seldom saturated, the rare gaseous discharge lamp lighting circuit using this, and the light device.
  • This invention provides new rare gas discharge arrangements, a method of operating rare gas discharge lamps, and lighting equipment utilizing such lamps.
  • Rare gas discharge lamps can be operated at a voltage of less than 2 kV to minimize discharge through the atmosphere and the amount of ozone thus produced. Such operation also minimizes operational noise. Even though they are operated at a lower voltage than that used for conventional lamps of this general type, our lamps provide adequate luminescence. Our lamps can be operated with either a sine wave or pulse driving power.
  • the invention is based on a recognition that it is appropriate to consider electrostatic capacity of the lamp arrangement in its design.
  • Our rare gas discharge lamp is generally of smaller diameter (less than 15 mm) than known lamps of this general type (typically 20-30 mm).
  • the lamp structure must have at least one external electrode and must satisfy the following equation: 0.01 ⁇ t / (D * ⁇ ) ⁇ 0.05.
  • the discharge vessel can be formed in various ways and from various materials.
  • One typical vessel is a long and slender (more than twice the length its diameter) glass bulb sealed at both ends.
  • the vessel can be completely transparent or it can have a transparent window from which light can emit
  • the vessel could also be formed from a translucent ceramic or other suitable materials having an appropriate dielectric constant, such as, for examples, flexible glass and half-hard glass, hard glass, quartz glass, etc.
  • the lamp must have a suitable electrostatic capacity which is a function of vessel outside diameter D (mm), thickness t (mm), and dielectric constant ⁇ according to the equation: 0.01 ⁇ t / (D * ⁇ ) ⁇ 0.05.
  • the diameter itself is not restricted. In order to radiate heat effectively it would be desirable for the outside diameter to be large. However, a large diameter causes the lamp to have a poor starting characteristic.
  • the range of 10-18mm is suitable, and the range of it is 12-18mm is more preferable.
  • Various vessel shapes can be used. It can be tubular or bent in one or more places, for examples, "U"-shaped, ring, and half-circle. Because the vessel may be bent Into an asymmetrical shape, the overall outside diameter may be 50-500 mm or even a greater range.
  • Suitable discharge media includes rare gases xenon, neon, argon, krypton, etc. Halides of the rare gas and the halogen simple substances other than the rare gas may be added. Suitable halogens include iodine, bromine, and chlorine.
  • the rare gas such as xenon
  • the rare gas Upon discharge, the rare gas, such as xenon, generates ultraviolet light which in turn excites a phosphor layer in the vessel.
  • the phosphor layer then generates useful visible light which is emitted from the lamp.
  • the pressure of the rare gas is not restricted. However, a it should generally be 100 or less k Pa and preferably 20-60 k Pa.
  • the present invention requires at least one pair of electrodes but it can include additional electrodes. Additional electrodes or pairs of electrodes can be used. At least one electrode Is external to the discharge vessel (both may be external). The external electrode is formed on the outside surface of the vessel or in close proximity to it.
  • the external electrode can be made of metal foil, conductive paint film, metal vapor coating film, transparency electric conduction film, metal mesh, comparatively thin metal boards, etc., such as the aluminum, or other suitable materials.
  • metal mesh refers to any structure that allows ultraviolet rays and/or visible light to pass, such as a wire nit like a net or metal having many holes punched therein.
  • the internal electrode is often of a generally cylindrical shape having a length corresponding to that of the discharge vessel. It can have a board-like or line-like form.
  • the internal electrode can be made of a conductive metal, for example, nickel, stainless steel, tungsten, molybdenum, etc.
  • the internal electrode may be formed as a mesh structure.
  • ultraviolet ray generated from the rare gas discharge can pass the mesh. If phosphor is formed on inside surface of the transparent discharge vessel, visible light can be easy to make.
  • the internal electrode is fixed so as to have a predetermined position within the transparent discharge vessel so that the electrical properties of the lamp remain constant and in order not to damage the phosphor layer etc.
  • the ends of the internal electrode are fixed to the transparent discharge vessel.
  • the internal electrode may not be uniform or symetrically placed within the vessel although it is common for it to be located on the main axis of the transparent discharge vessel.
  • seal means such as flare seal, bead seal, and pinch seal.
  • Some preferred embodiments of this invention utilize an aperture formed in the discharge vessel.
  • a reflective film is formed at portions of the discharge vessel other than at the aperture. This helps to increase the amount of light emitted from the aperture and in a specific direction. This is an advantage in certain lamp applications, such as for example, a copy machine lamp that illuminates a page to be copied.
  • the reflective film can be formed inside or outside of the vessel. If it formed on the inside of the vessel, it can be formed by particles, such as high oxidization titanium deposited on the inner surface of the vessel. Whatever structural arrangement is used, there must remain the ability for ultraviolet rays to reach the phosphor layer to excite them to produce visible light.
  • any structures positioned between positions whereat ultraviolet rays are generated and the phosphor layer must be permeable to ultraviolet rays. in using outside the lamp the ultraviolet ray generated by the rare gas discharge.
  • the phosphor layer is formed inside of the discharge vessel. In an aperture type lamp arrangement, the phosphor layer would not be formed at the aperture which is allowed to remain transparent so as to emit visible light.
  • phosphors can be used depending on the particular application for which the lamp is made.
  • a phosphor of white light systems such as the rare earth phosphor of the three (3) wave luminescence type or the halo phosphate phosphor, can be used.
  • phosphors which emits red, green, and blue primary color lights can be used. Examples include phosphate phosphor (LaPO4:Ce3+, Tb3+) of the rare earth or the green like BaAl12O19:Mn can be used for reading.
  • Other substances can be combined with phosphors as the application requires.
  • a protection film on the inside of the transparent discharge vessel.
  • This film can be made from alumina particles, etc. If a protective film is used, the phosphor layer is formed inside of the protection film.
  • This invention takes into consideration the electrostatic capacity of the structural configuration including the discharge vessel and its associated parts. By taking into consideration the electrostatic capacity it is possible to operate lamps having at least one external electrode at a lower voltage than is necessary with known lamps. Operating with a lower voltage reduces the amount of ozone produced and provides other operational advantages. There is still sufficient ultraviolet radiation generated to excite the phosphor layer and provide visible light.
  • a streamer discharge occurs across a gap in which there is dielectric. Inside the streamer there is an electrolytic dissociation from the cathode to the anode. Xenon emits only atomic luminescence (147 nm wavelength) when xenon pressure is low. But when the pressure is over 10 kPa, xenon emits luminescence at 172 nm .
  • the electrostatic capacity C of the transparent discharge vessel is a current-limiting impedance of value 1 1(2 ⁇ f * C), which limits tcauses an ozonaizer discharge to shifts at the arc discharge in the nature of discharge and prevents it from concentrating at a specific point.
  • the value of the current-limiting impedance is inversely proportional to frequency. For high frequency lighting the impedance becomes too small too much and it may stop acting as a current limiter. It is possible that in the case of a ramp driving voltage lamp current will change and the discharge will become unstable.
  • the amount of luminescence can be increased with respect to known lamp arrangements and that luminescence has a distribution that is quite uniform. Flickering is minimized.
  • Lamp current density ID (mA/cm 2 ) is represented by rated lamp current (mA) divided by the area (cm 2 ) of the external electrode when pressure of the rare gas is P (Pa) is expressed by the following relationship. -0.2666 * P + 410.8451 > ID > 0.1333 * P - 2.0132
  • the external electrode forms a ring-like portion around the discharge vessel which counters each internal electrode. (Flickering control of the brightness)
  • a transparent insulated covering can be used to enhance Insulation between electrodes. This could be a transparent heat shrinkage tube.
  • known lamp arrangements are operated with a rectangular pulse wave.
  • Our lamps can be operated with such driving power.
  • they can also be operated with a sine wave or half wave rectified sine wave. Doing so minimizes radiation noise and prevents significant decreases of light output.
  • a high frequency sine wave AC voltage can be applied, and the radiation noise can be further reduced.
  • Various types of driving voltages and wave shapes can be used, such as, for examples, pulse, half wave rectified sine wave, AC symmetrical AC, asymmetrical AC which has a direct current superimposed on a sine wave AC, pulse, etc.
  • the frequency of the driving should be 1 kHz. or more. Although a preferred range is 4 kHz. - 1 MHz. Generally 30 kHz. or more is especially desirable and flickering is significantly reduced at 100 kHz or more.
  • Luminescence efficiency improves using an asymmetrical wave. After glow Is produced In the pause between voltage wave. Insulation becomes easy and radiation noise decreases if the external electrode is grounded.
  • the rare gas discharge lamp and the high frequency power supply can be provided as an integrated unit or they can be separately provided. Dimming can be carried out using pulse width modulation (PWM).
  • PWM pulse width modulation
  • the outside diameter of the transparent discharge vessel is 12-18mm, the service power per unit length is 0.1-0.3 (W/mm) and the pressure- of; discharge medium is 20-60 kPa.
  • the electrostatic capacity can be made small enough so as to not prevent starting.
  • the service power per unit length 0. 1-0.3 (W/mm) prevents over heating of wall temperature, and the optical output is seldom saturated.
  • Luminescence efficiency can be made high by specifying the pressure of the discharge medium to be in the range of 20-60 kPa. However, if the pressure exceeds 60 kPa, flickering (Intense change of the optical output of the short cycle) becomes remarkable.
  • the frequency of the applied voltage be 100kHz or more. This helps to reduce flickering. It is also advantageous for there to be a certain relation between lamp current I (measured in A) and external electrode surface area S (mm 2 ) as follows: I / S ⁇ 0.5 (A/mm 2 )
  • the discharge medium sputters and the temperature of the internal electrode rises. This can causes problems such as the melting of part such as a case.
  • the external electrode is formed over the entire transparent discharge vessel except the portion acting as a light aperture. Radiation noise can be sharply reduced by grounding the external electrode. This also makes insulation between electrodes easy.
  • the internal electrode is fixed at least one end to the transparent discharge vessel.
  • the other end may be free. Both ends may be made into a structure which fixes both ends to the discharge vessel.
  • the rare gas discharge lamp constructed according to the present invention can be operated without the minute discharge when applying an AC voltage or a pulse voltage having a peak of 2 kV or less between electrodes.
  • the minute discharge changes with the amount of electrostatic capacity per unit area between the inside of the transparent discharge vessel and the external electrode. If the electrostatic capacity become too large, the minute discharge will be generated even when a low voltage is applied. Therefore, to prevent minute discharge, the electrostatic capacity should be kept small.
  • the electrostatic capacity per unit area of the transparent discharge vessel changes with the quality of the material and thickness which influence the permitivity of the transparent discharge vessel. By specifying electrostatic capacity to be as small as possible, minute discharge start voltage can be made high and the rare gas discharge lamp will not have minute discharge even when it is operated at a voltage peak of 2 kV.
  • lamp current can be increased by increasing the applied voltage, it is not practical to do so.
  • the applied voltage is a sine wave. This tends to reduce noise.
  • a pulse voltage such as a half wave rectified sine wave AC
  • light output can be increased due to after glow.
  • this form of driving voltage generates more noise.
  • the electrostatic capacity per unit area between the inside of the transparent discharge vessel and the external electrode is 0.03 ( ⁇ F/m 2 ).
  • the electrostatic capacity can be calculated from relative permitivity and thickness of the area of the transparent discharge vessel which becomes covered by the external electrode. Actual values can be measured with an LCR meter.
  • the rare gaseous discharge lamp has a phosphor layer formed on the inside surface of the transparent discharge vessel so that it may be excited by the rare gas discharge that occurs in the vessel between electrodes (external only or internal and external).
  • the lamps have at least one aperture for light to be emitted from the vessel.
  • the length of the transparent discharge vessel is not restricted, a good length is 200-500 mm and, generally, the outside diameter is 6-8mm, but suitably 20mm or less.
  • the external electrode should be formed along the longer side of the vessel and can be constituted by as many as 10-20 pieces.
  • the aperture may be the one long and slender continuous aperture or It may be a plurality of smaller ones for emitting light corresponding to localized discharges. Multiple pairs of electrodes can be provided for selecting particular discharge areas. This can be useful for generating light of different colors, mixing colors, and providing a video display.
  • the internal electrode is connected to one pole of the power supply and the external electrode is connected with the other power supply pole.
  • the rare gas discharge occurs between the domains of the internal electrode and the external electrode. If there is an aperture associated with each external electrode, light can be controlled simply by electrically selecting the desired external electrode and aperture. Two or more external electrodes can be connected to simultaneously to achieve desired effects. For multiple internal electrode arrangements, they can be switched as well.
  • Dimming can be achieved by modulating with a frequency lower than lighting frequency.
  • Color displays can be made by selecting phosphors for individual elements corresponding to primary colors that can be mixed to make other colors.
  • Generating ozone can be controlled while preventing luminescence by the leakage discharge which originates in the electrostatic capacity of the lighting circuit by regulating the frequency and the peak value of the electrostatic capacity by the external electrode, and the applied voltage in the predetermined range.
  • a cover board such as a shrink wrap can be applied over and between electrodes.
  • the peak value of voltage should be 2 kV or less, and the AC frequency should be 30 kHz. or more.
  • the rare gaseous discharge lamp can be used without any extra current-limiting impedance.
  • the electrostatic capacity should be sufficient.
  • the driving frequency of 30 kHz. or more should not be audible. It is practical to use semiconductor devices generate the driving frequency.
  • a high frequency inverter can be used as the power supply. Half wave rectification of the high frequency output may be carried out, and pulse voltage may be formed in the pulse lighting case.
  • the electrostatic capacity C is sufficient between the inside of the transparent discharge vessel and the outside for a lamp current I (measured in amps A) to flow using a lighting frequency f (Hz.) satisfying the equation C > I / (4 ⁇ rf*10 3 ) (F)
  • the value of electrostatic capacity C which becomes settled with the external electrode of the rare gaseous discharge lamp for not generating the minute discharge and the transparent discharge vessel to predetermined lamp current and predetermined lighting frequency is specified.
  • This invention provides lamps, methods of operating the lamps and various lighting equipment utilizing the lamps.
  • the equipment includes, for example, back light equipment, scanner, office automation equipment, display equipment, etc., back light equipment including both the "down" light type and the "side" light type.
  • Fig.1 is a transverse cross section showing a first embodiment of a rare gaseous discharge lamp according to the invention.
  • Fig.2 is a foreshortened vertical section view of the lamp shown in Fig. 1.
  • a transparent discharge vessel 1 has associated with it a phosphor layer 2, an external electrode 3 and an internal electrode 4.
  • An adhesive layer 5 made of polyamide holds external electrode 3 to the outer surface of vessel 1. Thickness of the adhesive layer 5 is 0.01 mm.
  • Transparent discharge vessel 1 has an outside diameter D of approximately 15 mm and thickness t of approximately 2.0 mm. It has a dielectric constant ⁇ .
  • Vessel 1 is a long and slender glass bulb made of borosilicate glass.
  • Phosphor layer 2 is formed in the inside of vessel 1 except at a portion thereof forming an aperture 1a for emitting light.
  • Vessel 1 contains 30 kPa of xenon, a rare gas.
  • Phosphor layer 2 and adhesive layer 5 are not shown in Fig. 2.
  • External electrode 3 is advantageously made of aluminum foil, but other suitable materials could be used. It is formed on the external surface of vessel 1 so that the vessel is surrounded except at aperture 1a which constitutes about 20% of its area.
  • Internal electrode 4 is made of nickel stick and has a diameter of approximately 2 mm. Other suitable materials could be substituted for the nickel. Internal electrode 4 is fixed at both ends of vessel 1.
  • a rare gaseous discharge lamp in accordance with the structure described can be operated by driving it with the appropriate signals.
  • the external electrode 3 is grounded.
  • a sinusoidal or pulse signal of preferably less than 2 KV is applied across the electrode so that the lamp draws about 200 mA of lamp current. It can be dimmed by pulse width modulating the driving signal at 50 kHz.
  • a lamp having a structure according to this invention and operated in this manner has sufficient surface area to dissipate the heat that will be generated.
  • the impedance due to the electrostatic capacity of the transparent discharge vessel is small. Current flows to its peak value rapidly when voltage is applied. This causes flickering.
  • the impedance is controlled to be within a certain range. This minimizes flickering and noise and allows the lamp to be operated with a driving voltage under 2 kV, and preferably about 1.5 kV.
  • Fig.3 is a graph showing the effect on flicker of the relationships among outside diameter D mm of the transparent discharge vessel, thickness t mm, and dielectric constant ⁇ .
  • the horizontal axis represents the ratio t / D * ⁇ and the vertical axis represents amount of flickering of the discharge as a percentage (%).
  • t / D * ⁇ is in inverse proportion to the electrostatic capacity of the lamp. As t / D * ⁇ becomes large, flickering decreases. The lamp operation is considered to be satisfactory if the flickering is 5% or less.
  • One suitable example uses a vessel 1 having an outside diameter of 12 mm, a length of 300 mm, filled with xenon at a pressure of 30kPa and operated at 1.5 kV.
  • Fig.4 is a enlarged light output wave form chart explaining concept of flickering that occurs during operation of a rare gaseous discharge lamp.
  • the horizontal axis represents time and the vertical axis represents amount of light output (arbitrary scales), respectively.
  • the rate of flickering Is the difference between peak and average values of light output. It is advantageous to minimize flickering.
  • Fig.5 is a graph which shows the relation of service power per unit length of the discharge vessel and the relative luminance output of the lamp.
  • the horizontal axis represents service power in W/mm and the vertical axis represents relative luminance as a percentage (%) for various situations.
  • the curve A data is for a vessel having an outside diameter of 12 mm
  • curve B data is for a vessel having an outside diameter of 15 mm
  • curve C data is for a vessel having an outside diameter of 18 mm.
  • As service power increases luminescence tends to saturate. However the larger diameter tube seems to have a larger range of luminescence before saturating.
  • optical output can be controlled by controlling service power in the range of 0. 1-0.3 (W/mm).
  • Fig.6 is the graph showing the relation of relative luminance as a function of time after starting the lamp. It also plots the wall temperature of vessel 1.
  • the horizontal axis represents time (min) from starting the lamp.
  • the vertical axis left side shows relativity luminance (plotted in curve D) as a percentage (%) and the vertical axis right side shows wall temperature (plotted in curve E) in degrees centigrade.
  • the lamp used for measuring this data was operated for 5000 hours. It had a diameter of 12mm, a length of 300 mm, was filled with xenon at a pressure of 30 kPa and was operated with a service power of 50 W (about 0.17 W/mm).
  • Fig.7 is the graph which shows the relationship of the pressure of the discharge medium (plotted on the horizontal axis in kPa), to both flickering (curve G plotted on the right vertical axis as a percentage %) and relative luminescence efficiency (curve F plotted on the left vertical axis as a percentage %).
  • a suitable range for discharge medium pressure is 20-60kPa to obtain reasonable values of luminescence efficiency while minimizing flicker.
  • Fig.8 is the graph which shows the relation of lamp current per surface area of the internal electrode vs. maintenance rate of luminance.
  • the horizontal axis shows the ratio of lamp current I to surface area S (A/mm 2 ), and the vertical axis shows maintenance rate of luminance (%). If I/S becomes greater than 0.5 A/mm 2 the maintenance rate of luminance falls abruptly. A larger electrode surface area helps to achieve an I/S less than 0.5 and therefore achieve a luminescence percentage that is high.
  • FIGS 9 and 10 help to explain the operation of a rare gaseous discharge lamp. They are enlarged sectional views of a principal part of a lamp according to the present invention. The phosphor layer is not shown. Electrons are attracted by external electrode 3 through a plasma which is generated by internal electrode 4 discharging in the presence of xenon inside vessel 1 during a negative phase. These electrons do not penetrate vessel 1 and adhere to the Inside of vessel 1, thereby causing it to become negatively charged. External electrode 3 develops a corresponding positive charge.
  • Figures 11-13 show a second embodiment of the invention using a mesh stricture external electrode.
  • Fig.11 is an elevational view.
  • Fig.12 shows an enlarged portion of the external electrode.
  • Fig.13 shows the ultraviolet ray luminescence domain.
  • External electrode 3 is a metal mesh structure that covers substantially all of vessel 1.
  • This mesh structure is similar to that of a knitted fabric. The mesh can be made large enough for vessel 1 to be inserted into it and then pulled so that it fits snugly around the vessel.
  • Domain 9 in Figure 13 illustrates the discharge mechanism and generation of ultraviolet rays for causing the phosphor layer to emit visible light. Domain 9 can actually be more effective than domains 7 and 8, shown In Figures 9 and 10 to provide good luminescence.
  • Vessel has a 10mm outside diameter, is 1mm of thick, is made of borosilicate glass and has a length of 300 mm.
  • the discharge medium is xenon at a pressure of 40 kPa.
  • the internal electrode 4 is a nickel stick having a diameter of 1 mm attached at both of its ends to vessel 1 through cobalt glass metal.
  • Phosphor layer 2 is (LaPO4:Ce and Tb), and is formed over 270 degrees of circumference of the vessel, thus leaving an aperture 1a for light to be emitted.
  • the power supply provides a lighting frequency of 30 kHz.
  • Fig.14 is the graph which shows, for this third embodiment, the relation of the lighting frequency (horizontal axis, kHz.) to minute discharge start voltage in the atmosphere (vertical axis, V). As shown, starting voltage is. relatively constant for a wide range of frequencies (100 kHz. to 1MHz.).
  • Fig.15 is the graph which shows the relation, for this third embodiment, of applied voltage at the time of predetermined lamp current flowing, to static capacity which is a function of the area of the external electrode, lighting frequency, etc.
  • the fixed lamp current was 170 mA for various lamps having various static capacities. They were operated at a lighting frequency of 50 kHz. and the size of the external electrode was 30*300*10 -8 m 2 . Because minute discharge occurs, the applied voltage should not be more than 2000V.
  • Fig.16 is an elevational view of a fourth embodiment.
  • Fig.17 is a enlarged side elevation. Reference numerals in common with previous embodiments will not be further explained.
  • Internal electrode 4 comprises a pair of cold cathodes 4A and 4B at respective ends of the transparent discharge vessel 1.
  • External electrode 3 has ring-like portions 3a and 3a corresponding respectively to cathodes 4A and 4B.
  • the phosphor layer is not shown.
  • rare gas discharge occurs uniformly for full length of the transparent discharge vessel.
  • Fig. 18 is a transverse cross section of a fifth embodiment of the rare gaseous discharge lamp of the present invention. Reference numerals in common with previous embodiments will not be further explained. This embodiment features only external electrodes. Electrodes 3A and 3B are on opposite sides of aperture 1a.
  • Fig.19 is a schematic diagram of a first embodiment of a piece of lighting circuit using a lamp according to the present invention. Reference numerals in common with previous embodiments will not be further explained.
  • the rare gaseous discharge lamp in this embodiment is the same structure as what is shown in Fig.1.
  • a low frequency AC power supply 11 and a high frequency power supply 12 provide power.
  • the high frequency power supply 12 is typically an inverter having a low frequency input from power supply 11.
  • Power supply 12 rectifies the power from supply 11 and generates a high frequency power with a frequency of 30 kHz. or more having a peak value of no more than 2kV to be applied across the electrodes.
  • Fig.20 is a circuit diagram showing a second embodiment of lighting circuit using a rare gaseous discharge lamp according to the present invention. Explanation of the common elements already explained in the first embodiment will not be further explained.
  • the rare gaseous discharge lamp is the same structure as shown in Fig.16.
  • the high frequency power supply equipment 12 includes high frequency generating circuit 12a, output transformer 12b, capacitor 12c, and diode 12d.
  • High frequency generating circuit 12a is usually an inverter and generates high frequency AC sine wave voltage having a frequency of about 30 kHz. or more.
  • the end of 2 order volume line of output transformer 12b is Power supply output is coupled to cold cathodes 4A and 4B through capacitor 12c.
  • the external electrode 3 is grounded. In this case ground provides a return path to complete the circuit.
  • a positive half wave of high frequency AC voltage is applied between each of the cold cathodes 4A and 4B, and the external electrode 3 through capacitor 12c. The power from this positive half wave causes the lamp to discharge.
  • Fig.21 is a circuit diagram showing the third embodiment of lighting circuit using a rare gaseous discharge lamp according to the present invention.
  • the power supply for this embodiment is different.
  • Power supply 12 includes a high frequency inverter which generates a high frequency sine wave.
  • An output of transformer 12b is connected to both of cold cathodes 4A and 4B.
  • the other end of output transformer 12b is connected to external electrode 3 and is also grounded. Radiation noise is reduced with respect to the Figure 20 arrangement.
  • Fig.22 is a circuit diagram showing the forth embodiment of the rare gaseous discharge lamp lighting circuit of the present invention.
  • the rare gas discharge lamp is similar to the one shown in Fig. 19. However, this one is operated at 100Torr, has an 8 mm outside diameter, a 317 mm lamp length, and is filled with xenon gas.
  • This embodiment includes internal electrode heating.
  • a transformer of power supply 12 includes two output windings 12b and 12c.
  • a timing switch S1 connects winding 12c to internal electrode 4 through capacitor C1 to provide heating.
  • Capacitor C1 is current-limiting impedance. Timing switch S1 can operate only for a limited time interval after starting by linkage with the timer.
  • Fig.23 is the graph which shows the relation of lamp starting voltage (vertical axis, volts) and the heating power of the internal electrode (vertical axis, watts).
  • the lighting frequency is 28 kHz.
  • the starting time is 10 seconds.
  • the Internal electrode has 8-ohms resistance.
  • Fig.24 shows the sixth embodiment of the rare gaseous discharge lamp lighting circuit of the present invention in a broken elevational view and a partial circuit diagram.
  • This embodiment is particularly suitable for use as a display.
  • This device includes three rare gaseous discharge lamps DLR, DLG, and DLB.
  • Each lamp has an aperture 1a, 1b, -, 1n respectively.
  • a phosphor layer of the red luminescence type Is formed on the Inner surface of the transparent discharge vessel 1 of the rare gaseous discharge lamp DLR.
  • the phosphor layer of the green luminescence type is formed in the inside side surface of the transparent discharge vessel 1 of the rare gaseous discharge lamp DLG, and a phosphor layer of the blue luminescence type is formed in the inside surface of the transparent discharge vessel 1 of the rare gaseous discharge lamp DLB.
  • lamp DLR provides a red luminescence
  • lamp DLG provides a green luminescence
  • lamp DLB provides a blue luminescence.
  • This color luminescence unit CPLY will form a number equal to the external electrodes 3a, 3b, --, 3n number of color pic cells.
  • a cover board 10 made from ceramics is arranged between adjoining external electrodes at a position corresponding to the middle of the internal electrode.
  • the contrast of the display is good and leakage of rare gas discharge between adjacent external electrodes is minimal.
  • the cover board 10 may be twisted.
  • Color luminescence unit CPLY is connected to the pole of another side of the high frequency power supply 12 of which one pole is grounded while each internal electrode 4 outputs high frequency voltage in case of the lighting.
  • Each external electrodes 3a, 3b, -, 3n is connected to the other pole of the high frequency power supply 12 through the switches Sa, Sb, -, Sn and grounding, respectively. It operates the thus and each external electrodes 3a, 3b, --, 3n in the state where it was grounded.
  • Fig.25 is a sectional view showing a down light type back light equipment according to another embodiment of the invention.
  • a rare gaseous discharge lamp' 21 is combined with a reflector 22 and an optical diffusion board 23.
  • Lamp 21 Is of the type shown in Fig.16.
  • Reflector 22 has an inside surface formed as a parabola reflective side and has attached to it a lamp holder 22a. Holder 22a supports the discharge lamp 21 so that it may be located in the focus of the parabola.
  • Lamp holder 22a and reflector 22 conduct heat away from lamp 21 in part through the connection of the lamp's external electrode which tends to generate heat. In addition, the external electrode may be made to contact with other structures that further heat dissipation.
  • Optical diffusion board 23 is attached to the aperture end of the reflector 22. This arrangement can be used for back lighting a liquid crystal display or other objects with or without additional optical elements.
  • Fig.26 is a sectional view of another embodiment of lighting circuit according to the invention, This embodiment is particularly well suited for side lighting. Again, elements in common with previous embodiments will not be explained.
  • a rare gaseous discharge lamp 31 is held in place by a lamp holder 32.
  • a light guide board 33 conducts light from lamp 31 which is shown
  • Holder 32 surrounds the discharge lamp 31 and is connected to the edge of light guide board 33.
  • Light from light guide board 33 is uniformly carried out from the front which can be advantageously made of a transparent acrylic resin.
  • Light entering board 33 from the lamp is reflected internally within board 33 and is emitted only at the desired surface for side lighting.
  • Fig.27 is a schematic sectional view showing a scanner arrangement in accordance with another embodiment of a lighting device of the present invention.
  • a rare gaseous discharge lamp 41 positioned within a reflector 45 provides light to a document former 44 that is reflected to a photo receiver 42.
  • a signal processor 43 analyzes signals indicative of the light received by photo receiver 42 to form an image of a document in the document former.
  • Document former 44 may include a transparent glass on which a document to be scanned can be placed face down.
  • Reflector 45 reflects light from the rare gaseous discharge lamp 41 outside toward the document former 44.
  • This type of scanner arrangement is well suited for office automation apparatus, such as the copy machine, the image scanner, and facsimile, etc.
  • Fig.28 is a broken elevational view of picture display 51 constituting another embodiment of a light device according to the invention.
  • a frame 51b holds color pic cell lamp units 52.
  • Frame 51b has a display side 51a.
  • Picture display 51 has a high frequency power supply, picture control means, etc. which are not shown, but have already been explained.
  • the color pic cell lamp units 52 include color pic cell lamp units such as CPLY previously described.
  • Picture display 51 can be used to display a video signal, such as a television video.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Electromagnetism (AREA)
  • Discharge Lamps And Accessories Thereof (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
  • Discharge Lamp (AREA)
EP99302495A 1998-03-30 1999-03-30 Edelgasgefüllte Entladungslampe, Leuchtschaltung und Leuchtvorrichtung Withdrawn EP0948030A3 (de)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
JP8473798 1998-03-30
JP8473798 1998-03-30
JP18272998 1998-06-29
JP18272998 1998-06-29
JP21395598 1998-07-29
JP21395598A JPH11345692A (ja) 1998-03-30 1998-07-29 放電灯点灯装置
JP21634798 1998-07-31
JP21634798 1998-07-31
JP1103199 1999-01-19
JP1103199 1999-01-19

Publications (2)

Publication Number Publication Date
EP0948030A2 true EP0948030A2 (de) 1999-10-06
EP0948030A3 EP0948030A3 (de) 1999-12-29

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1498932A1 (de) * 2002-04-19 2005-01-19 West Electric Co., Ltd. Entladungslicht und rücklicht
US7495376B2 (en) 2003-12-09 2009-02-24 Panasonic Corporation Light source device, lighting device, and liquid crystal display device
US7619361B2 (en) * 2004-01-14 2009-11-17 Panasonic Corporation Discharge lamp device including an airtight container filled with a noble gas
DE102009059705A1 (de) * 2009-12-18 2011-06-22 Sick Maihak GmbH, 79183 Gasentladungslampe

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5117160A (en) * 1989-06-23 1992-05-26 Nec Corporation Rare gas discharge lamp
EP0578953A1 (de) * 1992-07-06 1994-01-19 Heraeus Noblelight GmbH Hochleistungsstrahler

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5117160A (en) * 1989-06-23 1992-05-26 Nec Corporation Rare gas discharge lamp
US5117160C1 (en) * 1989-06-23 2001-07-31 Nec Corp Rare gas discharge lamp
EP0578953A1 (de) * 1992-07-06 1994-01-19 Heraeus Noblelight GmbH Hochleistungsstrahler

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
R. C. WEAST, EDITOR IN CHIEF: "Handbook of Chemistry and Physics" 1962 , THE CHEMICAL RUBBER CO. , OHIO, USA XP002121222 * page E-55 * *
TEKNA SEAL: "Electrical Properties: 2. Dielectric Properties" DESIGN GUIDELINES, [Online] XP002121221 Retrieved from the Internet: <URL:http://www.teknaseal.com/page3.html> [retrieved on 1999-10-29] *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1498932A1 (de) * 2002-04-19 2005-01-19 West Electric Co., Ltd. Entladungslicht und rücklicht
EP1498932A4 (de) * 2002-04-19 2006-12-27 Panasonic Photo & Lighting Co Entladungslicht und rücklicht
US7276851B2 (en) 2002-04-19 2007-10-02 West Electric Co., Ltd. Discharge lamp device and backlight having external electrode unit
US7495376B2 (en) 2003-12-09 2009-02-24 Panasonic Corporation Light source device, lighting device, and liquid crystal display device
US7619361B2 (en) * 2004-01-14 2009-11-17 Panasonic Corporation Discharge lamp device including an airtight container filled with a noble gas
DE102009059705A1 (de) * 2009-12-18 2011-06-22 Sick Maihak GmbH, 79183 Gasentladungslampe
US8482201B2 (en) 2009-12-18 2013-07-09 Sick Ag Gas discharge lamp

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