Patent Description:
There have conventionally been known a high-pressure mercury lamp and an excimer discharge lamp as an ultraviolet light-emitting device using a gas discharge. Also, a gas discharge light-emitting device using an ultraviolet light-emitting phosphor is disclosed in Patent Document <NUM>, and a gas discharge light-emitting device having a thin tube configuration suitable for a configuration of a flat light source has been proposed in, for example, Patent Documents <NUM> and <NUM>.

Patent Document <NUM> discloses an excimer discharge lamp configuration using an ultraviolet phosphor of UV-C band. However, this configuration has problems of requiring an expensive quartz glass envelope and requiring a high-voltage rectangular-wave alternating-current power supply for drive. Further, gas discharge devices for ultraviolet light emission using a gas discharge tube disclosed in Patent Documents <NUM> and <NUM> have a complicated electrode structure, and have not yet been developed to a practical level from a viewpoint of luminous efficiency and emission intensity. Patent document <NUM> merely discloses a display apparatus in which a front plate having display electrode pairs is disposed on the front side of a gas discharge tube array, and an insulating layer covering the display electrode pairs is disposed between outer wall surfaces of the front side of the tube array. Patent document <NUM> simply discloses a discharge lamp in which a pair of discharge electrodes are mounted on an external peripheral surface of a gas discharge tube along a longitudinal direction of the tube. Patent document <NUM> only discloses a discharge lamp in which a plurality of discharge channels are formed between an upper plate and a lower plate, and discharge electrode pairs disposed along the channels are disposed on the back side of the lower plate. Patent document <NUM> merely discloses a drive circuit for an external electrode-type gas discharge lamp including an inverter circuit and a booster transformer. Patent document <NUM> simply discloses a gas discharge lamp in which metallic foil electrodes formed on a resin film are pasted to a peripheral face of a glass tube with an adhesive.

In addition, to solve the foregoing problems, the present inventors have invented a novel gas discharge light-emitting device comprising a pair of long electrodes which is provided outside of a thin glass tube filled with a discharge gas and extends in a direction away each other from a gap interposed between adjacent ends of the electrodes (see, <CIT>). In this gas discharge light-emitting device, high efficient light emission throughout the entire length of an electrode arrangement region can be obtained by driving through application of a sine wave voltage between the pair of long electrodes. This plasma tube type gas discharge light-emitting device operates such that a trigger discharge is initially generated between adjacent ends of the electrodes during an increasing process of a sine wave voltage applied between both electrodes, and this trigger discharge is gradually grown so as to expand in longitudinal direction of the electrodes until the applied voltage reaches a peak value.

However, the present inventors have experienced, in an operating test for a gas discharge device provided with a pair of long electrodes according to the previous invention, a phenomenon in which an unnecessary spark discharge occurs along the side edges of the long electrodes outside the tube.

Specifically, when the device is driven by applying a sine wave voltage to one of a pair of long electrodes with the other being grounded, it is considered that, at the stage at which the applied voltage reaches a peak value, the inside of the tube is substantially in a conductive state due to a plasma throughout the entire length to have a potential corresponding to the peak voltage, and an unexpected spark discharge occurs in a gap between the curved surface of the tube and the side edge of the electrode having a ground potential, which face each other. In addition, even when air bubbles are present on a contact surface between the outer wall surface of the tube and the long electrodes due to fine irregularities on the outer wall surface of the tube, there is a risk of a spark discharge being caused at the portion where air bubbles are present. The spark discharge outside the tube causes generation of unpleasant ozone and damage on the electrode or the tube, and thus, not preferable from the viewpoint of safety.

The present invention is accomplished in view of the above circumstances, and aims to provide: a gas discharge light-emitting device for a light source, particularly for an ultraviolet light source, that has a simple configuration, is inexpensive, and has excellent emission efficiency, and that can prevent particularly a spark discharge on a wall surface outside a tube; and a drive circuit therefor. The present invention also aims to provide a gas discharge light-emitting device for a flat light source, particularly for an ultraviolet flat light source, which can be easily formed into a module to which a drive circuit is integrated and can provide light emission with high efficiency and high intensity with a compact size.

In the present invention, new practically improving is added in the gas discharge light-emitting device based on the previous invention. Briefly, the present invention is characterized by a configuration in which a discharge electrode is provided on the outer wall surface of a glass tube through an insulating layer. Specifically, the present invention is based on an idea in which an electric field from a plasma, in the tube, which causes a spark discharge is weakened by the insulating layer desposed between the discharge electrode and the outer wall surface of the tube to prevent the spark discharge along the outer wall surface of the tube.

A gas discharge UV light-emitting device according to the present invention is defined by claim <NUM>. A UV light source unit according to the present invention is defined by claim <NUM>. A gas discharge UV light-emitting module according to the present invention is defined by claim <NUM>. Preferred embodiments are set out in dependent claims <NUM>-<NUM> and <NUM>.

The main constituent features of the gas discharge light-emitting device according to the present invention are the glass tube, the phosphor layer provided inside the glass tube, and the discharge gas filled in the glass tube, so that the gas discharge light-emitting device does not contain toxic mercury. A pair of long discharge electrodes provided on the outer surface of the glass tube so as to extend along the longitudinal direction to be away from each other with a discharge gap being formed therebetween is simple, and according to the pair of long discharge electrodes, uniform light emission with high-efficient and high-intensity can be achieved throughout the entire length of the glass tube. In addition, the insulating layer being interposed between the discharge electrodes and the outer surface of the glass tube provides an effect of preventing a spark discharge along the side edge of the electrodes.

In addition, in the flat light source unit constructed by arraying multiple gas discharge light-emitting tubes parallel to one another, a drive circuit unit including, as a main component, a printed substrate serving also as a support substrate is integrally mounted below the common electrodes, which allows the light source to be constructed into a module. In this flat light source module, high-efficient and high-intensity surface light emission can be achieved, and further, this module can be handled with safety because no spark discharge occurs.

Accordingly, the flat light source module for ultraviolet light emission constructed by using an array of multiple gas discharge light-emitting tubes particularly provided with an ultraviolet light-emitting phosphor layer can be constructed not only to include no mercury but also to be capable of performing uniform and high-intensity ultraviolet radiation from a wide light-emitting surface without causing shadows, thereby providing an effect of expanding practical application for medical use or industrial use.

Preferable embodiments of the present invention will be described below in detail with reference to the drawings. It is to be noted that, for simplifying the description, the same components are identified by the same reference numerals.

<FIG> are each a schematic longitudinal sectional view and a transverse sectional view showing the basic configuration of a gas discharge light-emitting device according to the present invention as a first embodiment. An elongate glass tube <NUM> filled with a gaseous mixture of neon (Ne) and xenon (Xe) as a discharge gas constitutes an envelope that is a main component of the device. As shown in <FIG>, the glass tube <NUM> has a transverse section with a flat-oval shape, and has a front side upper part 1a and a back side bottom part 1b which are flat and face each other across a major axis. A pair of discharge electrodes <NUM> and <NUM> extending along the longitudinal direction of the glass tube <NUM> is arranged to extend to either side with an electrode gap <NUM> being interposed between adjacent ends thereof on the outer surface of the glass tube <NUM> on the back side bottom part through an insulating layer <NUM>. The discharge electrodes <NUM> and <NUM> are elongate along the glass tube <NUM>, so that they are referred to as long electrodes.

In a gas discharge light-emitting tube as a unit light source, that is, in a plasma tube <NUM>, the glass tube <NUM> which is a main component is formed such that a pipe-like preform of a borosilicate glass including silicon oxide (SiO<NUM>) and boron oxide (B<NUM>O<NUM>) as main components is redrawn to be formed into a thin tube with an outer diameter of <NUM>-<NUM> and a thickness of <NUM> or less. The glass tube <NUM> has a transverse section with a flat-oval shape with a major axis of <NUM> and a minor axis of <NUM> as shown in <FIG>. However, the glass tube <NUM> may have a transverse section with any shape such as a circle, rectangle, oblong, or trapezoid.

The insulating layer <NUM> which is the feature of the present invention is formed from an insulating tape or an insulating film affixed on the flat surface of the back side bottom part 1b of the glass tube <NUM> with a width larger than the major axis of the glass tube. The insulating layer <NUM> preferably has a thickness of <NUM>-<NUM>. If the insulating layer <NUM> is too thin, a function of preventing an external discharge is insufficient, and if it is too thick, it is difficult to obtain sufficient discharge expansion in the tube in relation to a discharge voltage. In addition, a heat-resistant tape or film made of a polyimide resin can be used for the insulating layer <NUM>. For example, Kapton tape (trade name) can preferably be used. A pair of long electrodes <NUM> and <NUM> is arranged on the lower surface of the insulating layer <NUM> as described later.

An ultraviolet light-emitting phosphor layer <NUM> is formed on the inner surface of the glass tube <NUM> on the back side bottom part 1b. This ultraviolet light-emitting phosphor layer <NUM> is excited by vacuum ultraviolet light (emission wavelength: <NUM>, <NUM>) generated by a gas discharge using a gaseous mixture of neon and xenon, thereby generating ultraviolet light or visible light having spectrum according to the characteristics of the phosphor.

If a gadolinium-activated phosphor (LaMgAl<NUM>O<NUM>:Gd) is used for the ultraviolet light-emitting phosphor layer <NUM>, ultraviolet emission of UV-B band having a peak wavelength with a narrow bandwidth at <NUM> can be obtained.

If a praseodymium-activated phosphor (YBO<NUM>:Pr or Y<NUM>SiO<NUM>:Pr) is used, ultraviolet emission of UV-C band having a peak wavelength at <NUM> can be obtained.

When the gas discharge light-emitting tube (plasma tube <NUM>) for an ultraviolet light source is constructed by forming the ultraviolet light-emitting phosphor layer <NUM>, it is important to set the thickness of the front side upper part 1a, serving as a light-emitting surface, of the glass tube <NUM> to be <NUM> or less from the viewpoint of the ultraviolet transmittance. The present inventors have proved through experiments that, even if borosilicate glass such as Pyrex (registered trademark) is used, transmittance of <NUM>% or more with respect to ultraviolet light having the UV-B wavelength band can be obtained by adjusting the thickness to be <NUM> or less. When the thickness of the light-emitting surface is set to be <NUM> or less, transmittance of <NUM>% or more even with respect to ultraviolet light having the UV-C wavelength band can be obtained.

In this case, the thickness at the back side bottom part 1b of the glass tube <NUM> where the insulating layer <NUM>, the long electrodes <NUM> and <NUM>, and the ultraviolet light-emitting phosphor layer <NUM> are disposed may be set larger than the thickness at the front side upper part 1a to enhance mechanical strength. The glass tube <NUM> in which the thicknesses of the surfaces facing each other are asymmetric can be implemented by a process control for shaping the glass preform.

In the configuration shown in <FIG>, adjacent proximal ends of a pair of long electrodes <NUM> and <NUM> arranged on the insulating layer <NUM> constitute trigger electrode portions 3a and 4a with the electrode gap <NUM> interposed therebetween, and a gas space corresponding to the electrode gap <NUM> becomes a trigger discharge portion <NUM>.

Further, extension portions extending to either side from the trigger electrode portions 3a and 4a in the direction away from each other constitute main electrode portions 3b and 4b, and a gas space corresponding to the main electrode portions 3b and 4b becomes a main gas discharge portion <NUM>. A pair of long electrodes <NUM> and <NUM> having the trigger electrode portions 3a and 4a and the main electrode portions 3b and 4b are respectively referred to as the X electrode <NUM> and the Y electrode <NUM> below.

An electrode gap length Dg of the electrode gap <NUM> is set within the range of <NUM>-<NUM>, as appropriate. In addition, the X electrode <NUM> and the Y electrode <NUM> are set to have a length more than three times to about ten times or more than the electrode gap length Dg. The arrangement of a pair of long electrodes enables uniform light emission throughout the entire length of the light-emitting tube.

When the electrode gap length Dg is set to be <NUM>, and the X electrode <NUM> and the Y electrode <NUM> each have a length of <NUM>, the gas discharge light-emitting tube <NUM> having an effective light-emitting region with a length of <NUM> is obtained based on the total size. It is to be noted that the length of the X and Y electrodes <NUM> and <NUM> that make a pair needs to be determined in consideration of the relationship between the peak value of an alternating drive voltage necessary for expanding the discharge throughout the entire length of the effective light-emitting region and the breakdown voltage of the electrode gap <NUM>.

The X electrode <NUM> and the Y electrode <NUM> may be directly formed on the lower surface of the insulating film <NUM>, which is affixed on the outer surface 1b of the bottom part of the plasma tube <NUM>, by printing conductive ink such as a silver paste or the like in advance, or may be formed by pasting or bonding a metal conductive foil such as a copper foil or an aluminum foil onto the lower surface of the insulating film <NUM>. Alternatively, an electrode substrate on which a metal conductive film having an electrode pattern is formed by printing or vapor deposition is prepared, and this electrode substrate can be pasted on the surface of the back side bottom part 1b of the plasma tube <NUM> through a base film serving as the insulating layer.

If the insulating layer <NUM> formed as a base of the X electrode <NUM> and the Y electrode <NUM> is made of a transparent fluoroplastic such as Teflon (registered trademark), the X and Y electrodes are preferably formed from a material having high light reflection characteristic, and for this point, it is effective to use an aluminum foil in particular. In this case, the electrode gap <NUM> may be a window open downward relative to the non-transmissive part of the X and Y electrodes <NUM> and <NUM>, so that emitted light exits to the back side, which may cause unevenness in an emission intensity distribution on the light-emitting surface. Therefore, when the insulating layer <NUM> is formed from a material having light transparency, it is preferable that at least the electrode gap <NUM> is closed by an insulating material having light reflection characteristic equal to the light reflection characteristic of the electrode material, such as a reflection tape.

In addition, if the surface of the plasma tube <NUM> is directly coated by a fluoroplastic having a function of satisfactorily transmitting ultraviolet light, such as Teflon (registered trademark), for example, this transparent coating layer can be functioned as the electrode insulating layer <NUM>. Specifically, resistance to weather and mechanical strength of the glass tube are enhanced by Teflon coating, and further, irregularities on the surface of the glass tube <NUM> are absorbed by Teflon coating, whereby air bubbles being present on the contact surface between the glass tube <NUM> and the electrodes can be eliminated to prevent a spark discharge. In addition, if the transparent insulating layer is used, a pair of translucent electrodes may be arranged on the front side of the glass tube.

The gas discharge light-emitting tube of a novel type according to the present invention, that is, the plasma tube <NUM>, has an external electrode type, and is driven by a sine wave voltage. When a sine wave voltage is applied to the Y electrode <NUM> of the pair of X and Y electrodes <NUM> and <NUM> with the X electrode <NUM> being grounded, a trigger discharge is generated at a point at which the voltage between the trigger electrode portions 3a and 4a exceeds a discharge start voltage of the trigger discharge portion <NUM> during an increasing process of the voltage.

Due to the priming effect caused by a supply of space charges from the trigger discharge portion <NUM>, a discharge start voltage is decreased, so that a new discharge is expanded toward either end of the main electrode portions 3b and 4b with the increase in the applied sine wave voltage.

On the other hand, as the feature of the external electrode type discharge device, charges (electrons and plus ions) having a polarity opposite to the polarity of the applied voltage are accumulated as wall charges on an inner wall surface of the glass tube corresponding to the discharged electrode, and the electric field caused by this wall charges cancel the electric field caused by the external voltage applied to the corresponding portions. Thus, the temporarily generated discharge is sequentially stopped. This operation principle is described in detail in the specification of <CIT> previously cited.

When the polarity of the applied sine wave driving voltage is inverted, the internal electric field caused by wall charges is combined with the electric field caused by the externally applied voltage, resulting in that the discharge is again generated at the trigger discharge portion <NUM>. Thereafter, the expansion and stop of the discharge with the increase in the applied sine wave voltage spread toward either end of the main electrode portions 3b and 4b as in the same manner as described above.

Due to the operation described above being repeated, the gas discharge and the light emission associated therewith are achieved. Notably, the sine wave drive voltage is set such that the discharge is expanded to either end of the X electrode <NUM> and the Y electrode <NUM> at its peak value. Alternatively, the length of the X electrode <NUM> and the Y electrode <NUM> is determined such that the peak value of the sine wave drive voltage does not exceed the breakdown voltage of the electrode gap <NUM>. Note that the driving frequency is a factor for determining an emission intensity, and is appropriately set to several <NUM>, for example, <NUM>.

While the discharge light-emitting operation described above is performed, the risk of a spark discharge generated in the gap between the electrodes and the both side edges of the curved surface portion on the bottom part of the plasma tube <NUM> can be avoided by the wide insulating film <NUM>. Specifically, the electrodes are not directly exposed on portions facing the curved surface portions at both side edges on the bottom part of the tube, whereby the electric field in the gap at said both side edges is not increased enough to cause the spark discharge.

<FIG> each show a schematic plan view and a transverse sectional view of a gas discharge light-emitting device according to a second embodiment of the present invention. The gas discharge light-emitting device according to the second embodiment is characterized by a configuration of a flat surface light source unit <NUM> of a light emitting tube array type in which a plurality of gas discharge light-emitting tubes (plasma tubes) <NUM> is arrayed parallel to one another.

As shown in <FIG>, multiple gas discharge light-emitting tubes <NUM>, in the present embodiment, six gas discharge light-emitting tubes <NUM>, for example, are arrayed on an insulating film <NUM> with a space SP therebetween which is about a tenth (<NUM>/<NUM>) the width of the tube. Preferably, an adhesive agent having excellent thermal conductivity, such as silicon grease, is used to fix the tubes <NUM> on the insulating film <NUM>. Due to the space SP between the adjacent tubes being filled with the adhesive agent, a spark discharge along the outer walls of the tubes can reliably be prevented. If a large number of gas discharge light-emitting tubes <NUM> are arrayed, several tubes may be collected as a unit block, and a space SP may be formed between the adjacent unit blocks. Due to the space SP being formed, the flat light source unit <NUM> has flexibility in the arraying direction of the gas discharge light-emitting tubes <NUM>.

In addition, as shown in <FIG>, the flat surface light source unit <NUM> has a configuration of a tube array in which six gas discharge light-emitting tubes <NUM> are supported parallel to one another on the common insulating film <NUM>. An X electrode <NUM> and an Y electrode <NUM> formed from a metal conductive film or foil are disposed on the lower surface of the insulating film <NUM> so as to be common to the respective gas discharge light-emitting tubes <NUM> with a gap having a length Dg therebetween across the respective tubes at almost the center thereof. In this configuration, while the X electrode <NUM> and the Y electrode <NUM> each have a pattern for covering almost the entire region of the tube array at the back side except for the gap Dg as shown in <FIG>, they extend to either end of each of the light-emitting tubes <NUM> with a length more than three times the gap Dg, as in the configuration in <FIG>. The insulating film <NUM> is formed from the Kapton tape (trade name) mentioned above, and the electrodes <NUM> and <NUM> are formed from an aluminum foil. The X electrode <NUM> and the Y electrode <NUM> formed from an aluminum foil are pasted on the back surface of the Kapton tape with a bonding agent or an adhesive agent. It should be noted that the X electrode <NUM> and the Y electrode <NUM> made of an aluminum foil are preferably formed to have a dimensional pattern such that ends thereof are slightly inward from both ends of the gas discharge light-emitting tubes <NUM> to avoid a risk of contact therebetween. The insulating film <NUM> having a function as a support member for the gas discharge light-emitting tubes <NUM> has a thickness of about <NUM> to <NUM>, and the aluminum foil constituting the X electrode <NUM> and the Y electrode <NUM> has a thickness of about <NUM>.

<FIG> shows a principled configuration of the flat light source unit <NUM> according to the present invention, and it is not preferable to use the unit <NUM> with the X electrode <NUM> and the Y electrode <NUM> being directly exposed on the lower surface of the unit <NUM>. As an actual flat light source, the surface where the X electrode and the Y electrode are disposed is covered by another insulating film which is not shown. In addition, from a practical point of view, in place of disposing the X electrode and the Y electrode on the lower surface of the insulating film <NUM>, a printed electrode substrate having formed thereon a conductive film with an electrode pattern with printing or vapor deposition is formed on another insulating substrate not shown, and the gas discharge tubes <NUM> supported on the insulating film <NUM> are overlaid on this insulating substrate.

<FIG> is a schematic sectional view of a gas discharge light-emitting device having a drive-circuit-integrated light source module configuration according to a third embodiment. As the module configuration, the flat light source unit <NUM> described in the second embodiment is overlaid on a printed substrate <NUM> constituting a drive circuit unit <NUM> through an impact absorbing layer <NUM>, and they are integrally stored in an external frame or a case <NUM>. Further, a translucent protection plate <NUM> is provided on the front surface of the flat light source unit <NUM>.

A soft insulating material having high thermal conductivity and impact absorption property, such as a silicon compound or a silicon sheet, is preferable for the impact absorbing layer <NUM>. An acrylic or fluoroplastic film or thin plate having excellent ultraviolet light transmittance is used for the protection plate <NUM>. The printed substrate <NUM> has mounted thereon components of the drive circuit unit <NUM> described later.

A pair of power feed terminals <NUM> and <NUM> which is brought into contact with the X electrode <NUM> and the Y electrode <NUM> on the back surface of the flat light source unit <NUM> is provided on the left and right sides on the top surface of the printed substrate <NUM>. The contact between the X electrode <NUM> and the power feed terminal <NUM> and between the Y electrode <NUM> and the power feed terminal <NUM> does not require DC connection in a strict sense, and an alternate drive voltage can be supplied to the flat light source unit <NUM> from the drive circuit unit <NUM> only by bringing the electrode and the corresponding terminal into a touch state where they only overlap each other directly or through a clip-shaped contact piece. Therefore, the light source unit <NUM> and the drive unit <NUM> can easily be separated from each other.

The drive circuit unit <NUM> generates a sine wave drive voltage to drive the flat light source unit <NUM>. The sine wave drive voltage is supplied to the Y electrode <NUM> from the power feed terminal <NUM> with the power feed terminal <NUM> defined as a ground being connected to the X electrode <NUM>, whereby the discharge light emission with the operation principle described previously can be obtained.

Note that the flat light source unit <NUM> with an emission area of <NUM><NUM> can be obtained by arranging, with an interval of <NUM>, thirty(<NUM>) gas discharge light-emitting tubes <NUM> having a flat-oval cross-sectional shape with a major axis of <NUM> and a minor axis of <NUM> and having an effective emission area with a length of <NUM>.

In addition, the diameter of the gas discharge light-emitting tube <NUM> is a maximum of <NUM>, and the total thickness of the light source module including the impact absorbing layer <NUM>, the printed substrate <NUM>, and the protection plate <NUM> on the front surface as well as the gas discharge light-emitting tube <NUM> is <NUM> or less. On the other hand, to drive this light source unit <NUM>, an alternating-voltage drive circuit having a peak voltage of several <NUM> V and a frequency of several <NUM> is needed. However, if the light source unit has only about thirty light-emitting tubes, it can beneficially be driven by a later-described popular compact power source with about several Watts.

Herein, when a drive circuit includes an inverter circuit that converts a DC voltage of <NUM> V (battery voltage) into a sine wave voltage of <NUM> and a compact transformer that boosts the peak value of the sine wave voltage to <NUM> V, the drive circuit unit including the battery may have a size within a capacity of about <NUM><NUM>.

Therefore, even when the previously mentioned light source unit <NUM> having a light-emitting surface of about <NUM><NUM> is used in the light-emitting device shown in <FIG>, and this light source unit <NUM> and the drive circuit unit <NUM> having the printed substrate <NUM> as a main component overlap each other and are integrated, the storage case <NUM> only requires a compact size of <NUM> x <NUM> with a thickness of about <NUM>.

<FIG> is a circuit diagram showing one example of a circuit structure of the drive circuit unit <NUM>. A battery BT to which a voltage can be set within a range of DC <NUM>-<NUM> V is connected to an inverter circuit section INV through an input plug PL1.

The inverter circuit section INV is composed of transistors Q1 and Q2, a coil L1, resistors R1 and R2, and a capacitor C1. An alternating output from the inverter circuit section INV is extracted from an output plug PL2 from a secondary winding of a step-up transformer TF. A sine wave alternating high voltage is obtained at the output plug PL2 by appropriately setting the circuit constant of each circuit component, and the obtained voltage is applied between the X electrode <NUM> and the Y electrode <NUM> of the gas discharge light-emitting tubes <NUM>. Note that the drive circuit unit <NUM> can cause the gas discharge light-emitting tube <NUM> to emit light through application of the similar voltage to the X electrode <NUM> and the Y electrode <NUM> in the first embodiment.

The frequency of the sine wave voltage can be adjusted within a range of <NUM> to <NUM> by varying the capacitance of the capacitor C1, and the peak value of the sine wave output voltage can be adjusted within the range of <NUM> V to <NUM> V by varying the voltage of the battery BT.

What is noted in the drive circuit shown in <FIG> is that there is no current limiting capacitor which is generally provided on an output line of the step-up transformer TF. One of the output lines of the step-up transformer is connected to a ground potential and the grounded X electrode <NUM> or <NUM> of the gas discharge tube <NUM>, and the other output line is directly connected to the Y electrode <NUM> or <NUM>. The gas discharge tube <NUM> according to the present invention becomes a complete capacitive load relative to the drive circuit unit <NUM>, whereby unnecessary power loss can be eliminated by eliminating an output capacitor.

The printed substrate <NUM> has mounted thereon circuit components <NUM>, such as a coil, a capacitor, and a transformer, that constitute the drive circuit. The printed substrate <NUM> is disposed on the lower part of the light source unit <NUM> with the mounted components facing downward. In addition, the battery BT serving as a power supply may be stored in a battery storage unit formed in the case <NUM>, or may be connected to an external power supply by a power supply connection line led from the printed substrate <NUM>.

While the gas discharge light-emitting device for ultraviolet light emission has been mainly described above, a visible light source using a phosphor which is excited by vacuum ultraviolet light due to gas discharge to emit light in a visible region can also be implemented. In addition, the gas discharge light-emitting device according to the present invention is also usable as a light source which uses light emission, in an ultraviolet region or a visible region, by a gas discharge itself without using a phosphor.

The gas discharge light-emitting tube serving as a light emission unit is thin with a diameter of several millimeters. Therefore, in the configuration of the flat light source unit <NUM> shown in <FIG>, a common flexible support substrate (not shown) is additionally provided, and the light source unit <NUM> is disposed on this substrate through an adhesive layer or a buffer layer, by which the exposure of the X electrode and the Y electrode can be prevented, and the support strength can be increased. Thus, the number of the light-emitting tubes <NUM> to be arrayed can be increased, and the length of the light-emitting tubes can be increased, which lead to an increase in a light-emitting surface as appropriate. The large-scale flat light source unit has a film shape with flexibility, thereby providing a benefit of easily obtaining a curved light-emitting surface for medical use or sterilization use.

In addition, while only the configuration provided with a pair of discharge electrodes has been described in the above embodiments, along the longitudinal direction of the glass tube, multiple pairs of the X electrode <NUM> and the Y electrode <NUM> can be arranged, the X electrode and the Y electrode are arranged in an alternating manner.

Claim 1:
A gas discharge UV light-emitting device comprising:
a glass tube (<NUM>) having an upper part (1a) and a bottom part (1b) facing each other on a transverse section thereof, and filled with a discharge gas, the upper part (1a) being defined as a light-emitting surface;
at least a pair of electrodes (<NUM>, <NUM>) disposed at a position facing an outer wall surface of the bottom part (1b) of the glass tube (<NUM>),
wherein the pair of electrodes (<NUM>, <NUM>) has a gap (<NUM>) constituting a trigger discharge gap therebetween and extends in a direction away from each other along a longitudinal direction of the glass tube (<NUM>) at each side of the gap (<NUM>), and the gas discharge UV light-emitting device further comprises an insulating layer (<NUM>) disposed between the electrodes (<NUM>, <NUM>) and the outer wall surface of the bottom part (1b) of the glass tube (<NUM>), the electrodes and the outer surface of the bottom part of each glass tube being on the insulating layer.