Discharge Lamp Device

Abstract

A discharge lamp device is provided that includes a light source device including a reflective surface. In the light source, noble gas not including mercury is excited to provide stable light emission and ozone or the like is prevented from being generated. This discharge lamp device includes airtight container (10) in which both end sections of a glass bulb are sealed. Airtight container (10) is filled with a discharge medium mainly including noble gas. One end section of airtight container (10) includes first electrode (11). Airtight container (10) is externally attached to insulating holder (20) having a square plate-like shape that includes penetration hole(s) (21) at one or a plurality of position(s). Holder (20) is fitted to second electrode (12) shaped to be a U-like groove so that a fixed interval between airtight container (10) and second electrode (12) is maintained. Three side faces (22) of holder (20) include protrusion (23) and second electrode (12) includes fitting hole (15) fitted with protrusion (23). By fitting protrusion (23) with fitting hole (15), holder (20) is prevented from disengaged from second electrode (12).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating Embodiment 1 of a discharge lamp device according to the present invention.

FIG. 2 is a perspective view illustrating Embodiment 1 of a holder constituting the discharge lamp device according to the present invention.

FIG. 3 is a cross-sectional view illustrating Embodiment 1 of the discharge lamp device according to the present invention.

FIG. 4 is a front view illustrating the main part of Embodiment 1 the discharge lamp device according to the present invention.

FIG. 5 illustrates a relation between an ozone generation amount and a distance between an airtight container and a second electrode.

FIG. 6 is a perspective view illustrating holders of Embodiment 1 of the discharge lamp device according to the present invention arranged in parallel to one another.

FIG. 7 is a perspective view illustrating Embodiment 2 of a holder constituting the discharge lamp device according to the present invention.

FIG. 8 is a front view illustrating the main part of Embodiment 2 of the discharge lamp device according to the present invention.

FIG. 9 is a perspective view illustrating Embodiment 3 of a holder constituting the discharge lamp device according to the present invention.

FIG. 10 is a front view illustrating the main part of Embodiment 3 of the discharge lamp device according to the present invention.

FIG. 11 is a perspective view illustrating Embodiment 4 of the discharge lamp device according to the present invention.

FIG. 12 is a perspective view illustrating Embodiment 5 of the discharge lamp device according to the present invention.

FIG. 13 is a perspective view illustrating Embodiment 6 of the discharge lamp device according to the present invention.

FIG. 14 is a perspective view illustrating Embodiment 7 of the discharge lamp device according to the present invention.

REFERENCE MARKS IN THE DRAWINGS

10 Airtight container

11 First electrode

12 Second electrode

13 Fluorescent material layer

14 Reflective surface

15 Fitting hole

20 Holder

21 Penetration hole

22 Side face

23 Protrusion

24 Empty section

30 Reflection member

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiment 1

Embodiment 1 of a discharge lamp device according to the present invention will be described with reference to FIG. 1 to FIG. 6. The discharge lamp device according to Embodiment 1 includes airtight container 10 in which both end sections of a glass bulb (not shown) are sealed. The interior of airtight container 10 is filled with discharge medium mainly including noble gas. One end section or both end sections of airtight container 10 include(s) first electrode 11. Insulating holder 2 is externally attached to airtight container 10 at one or a plurality position(s) of airtight container 10 (two positions in FIG. 1). Holder 20 is attached with second electrode 12.

Airtight container 10 is made of material such as glass (borosilicate glass, silica glass, soda glass, lead glass), organic matter (e.g., acryl), or other translucent materials. Airtight container 10 basically has a straight pipe-like shape but also may have an L-like shape, a U-like shape, or a rectangular shape. Airtight container 10 basically has a circular cross section but also may have a different cross section such as an oval, triangular, or square cross section. Airtight container 10 generally has an outer diameter from 1.0 mm to 10 mm but also may have an outer diameter of about 30 mm. Airtight container 10 has a thickness of about 0.1 mm to 1.0 mm.

Airtight container 10 as described above is filled with a discharge medium (not shown). The discharge medium is composed of noble gas such as xenon, neon, argon, or krypton and also may be composed of noble gas including mercury. The pressure of gas filled in airtight container 10 (i.e., pressure in airtight container 10) is about 0.1 kPa to 76 kPa.

When noble gas such as xenon generates ultraviolet by discharge, an inner circumference of airtight container 10 is layered with fluorescent material layer 13 for converting ultraviolet to visible light. Fluorescent material layer 13 is made of material such as the one for a fluorescent lamp for general lighting or a plasma display for example. However, material of fluorescent material layer 13 also may be changed so that light other than white light (e.g., red, green, or blue light) can be generated.

First electrode 11 is made of metal such as tungsten or nickel for example and the surface is partially or entirely covered by a metal oxide layer such as the one composed of cesium oxide, barium monoxide, or strontium oxide. The metal oxide layer as described above can reduce a lighting starting voltage and can prevent deterioration of an electrode due to ion collision. The first electrode as described above is connected with a lead wire (not shown) connected to a lighting circuit (not shown).

Holder 20 has a square plate-like shape as shown in FIG. 2 that includes penetration hole 21 to which airtight container 10 is inserted. Three side faces 22 have protrusions 23, respectively. Protrusion 23 is not limited to the shown rectangular parallelepiped-like shape and also may be formed by one or two or more cylindrical shape(s). Holder 20 as described above is made of material having insulation, transparency, and elasticity such as silicon resin or silicon rubber.

Second electrode 12 includes opening 16 for emitting light emitted from airtight container 10 and is formed to have a U-like groove that surrounds airtight container 10 by the three sides and that has the same length as that of airtight container 10. Airtight container 10 is opposed to reflective surface (reflector) 14. Second electrode 12 is made of metal having superior light reflectivity such as copper, aluminum, or stainless so that second electrode 12 can entirely work as reflective surface 14.

Holder 20 is fitted with one or two or more part(s) of second electrode 12 (two positions in FIG. 1). Specifically, second electrode 12 includes fitting holes 15 that are provided at positions at which holder 20 is provided and that are fitted with protrusions 23 formed in holder 20. By fitting protrusions 23 with fitting holes 15 at three positions as shown in FIG. 3 and FIG. 4, holder 20 can be not only prevented from moving in second electrode 12 but also prevented from disengaged from second electrode 12. This can maintain a fixed distance between airtight container 10 inserted to penetration hole 21 of holder 20 and second electrode 12.

The shortest distance between airtight container 10 and second electrode 12 is in a range from 0.1 to 2.0 mm. The shortest distance of 0.1 mm or more can prevent airtight container 10 and second electrode 12 from having a part at which they are abutted to each other or a clearance therebetween. Thus, ozone for example can be prevented from being caused.

FIG. 5 shows a result of measurement of a relation between an ozone generation amount and the shortest distance between airtight container 10 and second electrode 12. This measurement was done under typical conditions including the maximum voltage between first electrode 11 and second electrode 12 of 5 kV, a thickness of airtight container 10 of 0.1 mm, an inner diameter of airtight container 10 of 2.0 mm, discharge medium of Xe-Ar mixed gas (ratio of Xe:Ar=7:3), a gas pressure of 10 kPa, and airtight container 10 made of borosilicate glass having a dielectric constant of about 5.8. As shown in FIG. 5, no ozone is generated at all when the shortest distance is 0.1 mm or more. It was confirmed that the ozone generation amount in this measurement was below a threshold of a measuring instrument.

However, when the shortest distance between airtight container 10 and second electrode 12 is excessively long, the discharge medium in airtight container 10 cannot be sufficiently excited. Thus, this shortest distance should be 2.0 mm or less when the maximum voltage between the electrodes is 5 kV.

Airtight container 10 and second electrode 12 generally have therebetween air. An experiment showed that, when air exists between airtight container 10 and second electrode 12, dielectric breakdown is not influenced by the inner diameter of airtight container 10 (1.0 mm to 10 mm), the type of the discharge medium, the inner pressure of airtight container 10, or the shape of airtight container 10. It was also found that that dielectric breakdown is more easily caused when the thinner thickness airtight container 10 has and the higher maximum voltage the electrodes have therebetween.

The discharge lamp device having the structure as described above is used as a backlight used for a liquid crystal display for example by an arrangement in which the discharge lamp device is provided along an end face of a light guide plate (not shown) or by another arrangement in which the plurality of discharge lamp devices having the structure as described above are provided to be parallel to one another, as shown in FIG. 6, on a back face of a light guide plate (not shown). In any of these arrangements, opening 16 of second electrode 12 is opposed to the light guide plate.

When the plurality of discharge lamp devices are provided to be parallel to one another, corners of holders 20 at a side at which no second electrode 12 is provided are joined at juncture section 24. The integrated structure of holders 20 with juncture sections 24 can simplify an assembly operation. Alternatively, holder 20 also may be separately provided from juncture section 24. In this case, an arbitrary number of holders 20 can be joined.

When a lighting circuit applies voltage between first electrode 11 and second electrode 12, discharge is caused to excite a discharge medium and ultraviolet is caused when a ground state is started. This ultraviolet is converted to visible light when the ultraviolet passes through fluorescent material layer 13 and is emitted from airtight container 10. This visible light is reflected by a radiant section of second electrode 12 and is incident in a light guide plate. Then, the entire surface of the light guide plate emits light. A fixed interval between airtight container 10 and second electrode 12 is maintained by externally attaching airtight container 10 to holder 20 so that protrusions 23 formed in holder 20 are fitted with fitting holes 15 formed in second electrode 12. This prevents ozone or the like from being generated to prevent airtight container 10 from being broken. Thus, the discharge lamp device can have a longer service life.

Embodiment 2

Embodiment 2 will be described with reference to FIG. 7 and FIG. 8. Embodiment 2 is characterized in that a relation between thickness a of holder 20 in a longitudinal direction of airtight container 10 and width b of protrusion 23 in the longitudinal direction of airtight container 10 is determined to be a>b. Specifically, holder 20 has a thickness that is thicker than a width of protrusion 23.

When a user holds a liquid crystal display using the discharge lamp device of the present invention as a backlight by hands, a risk may be caused where the discharge lamp device receives pressure from a side to deform holder 20 and thus a distance between airtight container 10 and second electrode 12 is changed. Another risk may be caused where dust may come into second electrode 12 via a clearance between protrusion 23 and fitting hole 15 formed in second electrode 12.

Thus, the structure according to Embodiment 2 can minimize the deformation of holder 20 even when being subjected to the pressure as described above. Thus, a fixed distance between airtight container 10 and second electrode 12 can be maintained. Furthermore, side face 22 completely sealing fitting hole 15 can prevent dust from coming into second electrode 12. Since holder 20 is formed to have a thick thickness, holder 20 is preferably made of material having a transparency from a viewpoint of improving the optical transparency. The other structures, functions and effects of Embodiment 2 are the same as those of Embodiment 1 and thus will not be further described.

Embodiment 3

Embodiment 3 will be described with reference to FIG. 9 and FIG. 10. Embodiment 3 is characterized in that holder 20 is structured as described below. Specifically, length a of holder 20 in the longitudinal direction of airtight container 10 is determined such that a relation between length a₁ at a side from which airtight container 10 emits light and length a₂ at a side at which second electrode 12 is provided and which is opposed to opening 16 is a₁<a₂. Specifically, holder 20 is formed to have an almost trapezoidal shape when seen from the front and holder 20 has a thickness that is reduced in a direction along which light is emitted. A relation between a₂ and width b of protrusion 23 of holder 20 is determined to be a₂>b from the viewpoint of securing the rigidity of holder 20. A relation between a₁ and b is determined to be a₁<b from the viewpoint of improving the radiation efficiency of light emitted from airtight container 10.

The structure as described above provides not only the function and effect of Embodiment 2 but also forms holder 20 so that the thickness of holder 20 is increased toward a side at which second electrode 12 is provided and is reduced in a direction along which light is emitted from airtight container 10. Thus, holder 20 can have an improved rigidity while securing the light intensity of the discharge lamp device. However, the shape of holder 20 seen from the front is not limited to the trapezoidal shape and may be any shape so long as the above condition a₁<a₂ is satisfied. When holder 20 is made of material having a high transparency, light emitted from airtight container 10 can have a further improved radiation efficiency. The other structures, functions and effects of Embodiment 3 are the same as those of Embodiment 1 and thus will not be further described.

Embodiment 4

Embodiment 4 will be described with reference to FIG. 11. Embodiment 4 is characterized in that empty section 25 is formed at one side face 22 of holder 20. Empty section 25 is provided at a side from which light is emitted from airtight container 10 (i.e., at a side at which opening 16 of second electrode 12 is provided). Empty section 25 has a width that is smaller than an outer diameter of airtight container 10. The thickness of holder 20 may be equal to the width of protrusion 23 as shown in FIG. 4 as in Embodiment 1 or may be thicker than the width of protrusion 23 or may be reduced in a direction along which light is emitted as in Embodiment 2 and Embodiment 3.

By the above-described structure, airtight container 10 can be attached in penetration hole 21 of holder 20 while holder 20 while being attached in second electrode 12. Thus, an assembly operation is improved than that in the case of holder 20 having no empty section 25. In order to easily attach airtight container 10 into penetration hole 21 of holder 20, opposed faces of empty section 25 may be chamfered. The width of empty section 25 smaller than the outer diameter of airtight container 10 prevents airtight container 10 attached in penetration hole 21 of holder 20 from being disengaged. The other structures, functions and effects of Embodiment 4 are the same as those of Embodiment 1 and thus will not be further described.

Embodiment 5

Embodiment 5 will be described with reference to FIG. 12. Embodiment 5 is characterized in that holder 20 having a rectangular column-like shape is formed to have the same length as that of airtight container 10 and the center of holder 20 has penetration hole 21 to which airtight container 10 is inserted. As in Embodiment 4, one side face 22 of holder 20 includes empty section 25 having a width smaller than the outer diameter of airtight container 10. Three side faces 22 of holder 20 at which no empty section 25 is formed are covered by second electrode 12 as a U-like groove. However, second electrode 12 also may have a stripe-like shape adhered to a surface opposite to empty section 25. The above-described structure allows airtight container 10 to be inserted to penetration hole 21 of holder 20 so that a fixed interval between airtight container 10 and second electrode 12 adhered to holder 20 can be securely maintained.

As in Embodiment 1, Embodiment 5 may provide protrusion 23 at side face 22 of holder 20 and may provide second electrode 12 with fitting hole 15 to which protrusion 23 is attached. Furthermore, Embodiment 5 also may arrange holders 20 so as to be parallel to one another so that corners of holder 20 may be connected by linkage member 24. Although empty section 25 is not always required, empty section 25 is preferably provided because empty section 25 facilitates an operation for attaching airtight container 10 into holder 20 extending in an axial direction. The other structures, functions and effects of Embodiment 5 are the same as those of Embodiment 1 and thus will not be further described.

Embodiment 6

Embodiment 6 will be described with reference to FIG. 13. As in Embodiment 5, Embodiment 6 is characterized in that the center of rectangular column-like holder 20 having almost the same length as that of airtight container 10 has penetration hole 21 to which airtight container 10 is inserted and that one side face 22 has empty section 25 that has a width smaller than the outer diameter of airtight container 10. However, Embodiment 6 is different from Embodiment 5 in that second electrode 12 is buried in holder 20 at a side at which no empty section 25 is formed. By burying second electrode 12 in holder 20, an interval between airtight container 10 and second electrode 12 is maintained to be shorter than in the case of Embodiment 5 and second electrode 12 can be prevented from being disengaged from holder 20. In addition to the shown groove-like shape, second electrode 12 also may have a stripe-shape.

As in Embodiment 1, Embodiment 6 also may arrange discharge lamp devices to be parallel to one another so that corners of holder 20 may be connected by linkage member 24. Empty section 25 is not always required. The other structures, functions and effects of Embodiment 6 are the same as those of Embodiment 5 and thus will not be further described.

Embodiment 7

Embodiment 7 will be described with reference to FIG. 14. As in Embodiment 6, Embodiment 7 is characterized in that the center of rectangular column-like holder 20 having almost the same length as that of airtight container 10 has penetration hole 21 to which airtight container 10 is inserted and that one side face 22 has empty section 25 having a width smaller than the outer diameter of airtight container 10. Embodiment 7 is also characterized in that second electrode 12 is buried in holder 20 at a side at which no empty section 25 is formed. However, Embodiment 7 is different from Embodiment 6 in that reflection member(s) 30 is/are provided at three surfaces of holder 20 at which no empty section 25 is formed or at only one surface opposite to empty section 25. Second electrode 12 is composed of one or two or more rod-like electrode wire(s). This structure can reduce the interval between second electrode 12 and airtight container 10 and can increase the interval between reflection section 14 and airtight container 10.

Second electrode 12 may be a transparent electrode mainly including tin oxide and indium oxide for example. This can prevent light emitted from airtight container 10 from being blocked by second electrode 12.

The present invention is not limited to Embodiments 1 to 7 and various modifications can be made within a scope of technical matters described in claims. For example, in addition to first electrode 11 and second electrode 12, a third electrode (not shown) for facilitating a preliminary control of discharge or start of discharge also may be provided in or out of airtight container 10. Furthermore, second electrode 12 is not limited to the U-like groove shape and also may be shaped to be a C-like groove or a V-like groove to surround airtight container 10. Holder 20 also may be shaped to correspond to the shape of second electrode 12.

INDUSTRIAL APPLICABILITY

The discharge lamp device according to the present invention prevents ozone or the like from being generated to prevent an airtight container from being broken. Thus, the discharge lamp device according to the present invention is useful as a backlight for example used for a liquid crystal display for example.

The prevention of ozone or the like is particularly advantageous because the breakage of an airtight container can be prevented and thus the discharge lamp device can have a longer life.

Furthermore, the second electrode including a reflective surface can allow the discharge lamp device to have smaller size and reduced cost. Thus, a liquid crystal display including this discharge lamp device for example also can have smaller size and reduced cost.

Claims

1. A discharge lamp device comprising: an airtight container filled with a discharge medium mainly including noble gas;a first electrode provided in the airtight container;a second electrode that includes an opening through which light emitted from the airtight container is emitted, that is provided to have a predetermined interval to the airtight container, and that includes a reflective surface; andan insulating holder that is externally attached to the airtight container and that maintains the predetermined interval,wherein the holder includes a penetration hole to which the airtight container is inserted and includes a protrusion at a position at which the second electrode is provided, and the second electrode includes a fitting hole fitted with the protrusion of the holder.

2. (canceled)

3. The discharge lamp device according to claim 1, wherein: a relation between a length a of the holder in a direction along which the airtight container is inserted and a length b of the protrusion in the insertion direction is determined to be a>b.

4. The discharge lamp device according to claim 1, wherein: a length a of the holder in a direction along which the airtight container is inserted is determined such that a relation between length a1 at a side from which the airtight container emits light and length a2 at a side at which the second electrode is provided is a1<a2.

5. The discharge lamp device according to claim 1, wherein: the holder is made of transparent material and is formed to have the same length as that of the airtight container.

6. The discharge lamp device according to claim 5, wherein: the second electrode is buried in the holder to have a predetermined interval to the airtight container.

7. A discharge lamp device comprising: an airtight container filled with a discharge medium mainly including noble gas;a first electrode provided in the airtight container;a second electrode buried in the holder to have a predetermined interval to the airtight container;an insulating holder that is made of transparent material to have the same length as a length of the airtight container and that includes a penetration hole to which the airtight container is inserted; anda reflection member that includes an opening through which light emitted from the airtight container is emitted and that is externally provided to the second electrode.

8. The discharge lamp device according to claim 1, wherein: the holders are arranged to be parallel to one another and corners at a side at which light emitted from the airtight container is emitted are joined.

9. The discharge lamp device according to claim 7, wherein: the holder includes an empty section that is provided at a side at which light emitted from the airtight container is emitted and that has a width smaller than an outer diameter of the airtight container holders are arranged to be parallel to one another and corners at a side at which light emitted from the airtight container is emitted are joined.

10. The discharge lamp device according to claim 1, wherein: holder includes an empty section that is provided at a side at which light emitted from the airtight container is emitted and that has a width smaller than an outer diameter of the airtight container.

11. The discharge lamp device according to claim 7, wherein: the holder includes an empty section that is provided at a side at which light emitted from the airtight container is emitted and that has a width smaller than an outer diameter of the airtight container.

12. The discharge lamp device according to claim 1, wherein: the predetermined interval is in a range from 0.1 mm to 2.0 mm at the shortest.

13. The discharge lamp device according to claim 7, wherein: the predetermined interval is in a range from 0.1 mm to 2.0 mm at the shortest.

14. The discharge lamp device according to claim 1, wherein: the discharge medium includes at least xenon gas and a fluorescent material layer is layered on an inner circumference of the airtight container.

15. The discharge lamp device according to claim 7, wherein: the discharge medium includes at least xenon gas and a fluorescent material layer is layered on an inner circumference of the airtight container.