KR20050100539A - Flat fluorescent lamp having improved discharge efficiency - Google Patents

Abstract

The present invention relates to a flat fluorescent lamp for a flat panel display device, and more particularly, to maximize the discharge efficiency and minimize the non-light-emitting area to maintain the optimal brightness uniformity of the discharge channel width of the area where the electrode is located. The present invention relates to a fluorescent lamp having a discharge space structure which is differentiated in an effective light emitting area of a non-light emitting area and other parts, and which has an electrode shape that enables discharge even at a low discharge start voltage.

 A flat fluorescent lamp according to the present invention comprises two substrates; A sealing member arranged along edges of the two substrates to seal a discharge space formed between the two substrates; Barrier ribs protruding side by side on the opposite surfaces of the two substrates to form a discharge channel to form a discharge space; And electrodes arranged on both end sides of the substrate in a form orthogonal to the partition wall to excite discharge gas filled in a discharge space formed between the two substrates, wherein each partition wall overlaps the electrode. And forming partitions in the effective light emitting region between the two electrodes so that the discharge channel width of the effective light emitting region is narrower than the discharge channel width of the non-light emitting region.

Description

Flat fluorescent lamp with improved discharge efficiency {FLAT FLUORESCENT LAMP HAVING IMPROVED DISCHARGE EFFICIENCY}

The present invention relates to a flat fluorescent lamp for a flat panel display device, and more particularly, to maximize the discharge efficiency and minimize the non-light-emitting area to maintain the optimal brightness uniformity of the discharge channel width of the area where the electrode is located. The present invention relates to a flat fluorescent lamp having a discharge space structure differentiated in a non-light emitting area and an effective light emitting area in other parts, and having an electrode shape that enables discharge even at a low discharge start voltage.

Generally, flat panel displays include light emitting types such as CRT, FED, PDP, and organic EL, and light receiving types such as liquid crystal display (LCD). Among them, the liquid crystal display does not have a structure that emits light itself and thus cannot implement an image unless external light is irradiated. Accordingly, an image must be realized by installing a back light unit (back light unit) which is a separate light source.

The conventional backlight unit has a method of making the light emitted from a cold cathode fluorescent lamp (CCFL) into a surface light source using a light guide plate, a method of making a plurality of cold cathode fluorescent lamps on the back of the liquid crystal panel to a surface light source, Then, the discharge gas (rare gas such as Xe, Ne, etc.) is charged between the two flat glass substrates, and a discharge is generated by applying power to the arranged electrodes to cause the phosphor coated on the substrate to emit light to form a surface light source. do.

Referring to FIGS. 1A and 1B illustrating a lamp assembly and a fluorescent lamp using a conventional flat fluorescent lamp, first, the lamp assembly 110 is a hexahedron having a flat lamp 120 installed therein and having an open top. The frame 111, the transparent plate 113a and the diffuser plate 113b are laminated and made of light diffusing means 113 covering the upper opening of the frame 111.

As shown in FIGS. 1A and 1B, the conventional flat lamp 120 includes two substrates 121 and 123 and a sealing member 125 for blocking the outside between discharge electrodes formed between the two substrates. A plurality of barrier ribs 130, which form channels forming the discharge space 150, is formed on the back substrate 121. The transparent substrate is called the front substrate 123. The phosphor layer 127 is coated on the inner circumferential surface of the discharge space 150 partitioned by the partition wall 130, and the discharge space is filled with rare gas such as Ar, Ne, and Xe, or Hg. In addition, an electrode for causing barrier discharge is provided inside or outside the discharge space, and a lamp having an external electrode 140a and 140b type is illustrated.

In addition, when mercury (Ag) is used as the excitation source, the phosphor layer 127 emits light by ultraviolet rays of 254 nanometers and ultraviolet rays of 173 nanometers when xenon (Xe) is used. In FIG. 1B, a metal 129 impregnated with mercury as an excitation source is located in the discharge space.

When power is applied to the discharge electrodes 140a and 140b of the flat fluorescent lamp 120 having such a structure, the phosphor layer is excited by ultraviolet rays generated by gas discharge between the discharge electrodes, and then is converted to a stable state. By generating visible light (surface light emission), an image of the liquid crystal display is realized.

However, the conventional flat fluorescent lamp has a short distance between the electrode and the ultraviolet ray emission efficiency of the discharge gas, so that the visible light conversion efficiency is 30 lm / W or less. Therefore, in order to increase the visible light conversion efficiency, the driving power must be increased, thereby increasing the power consumption, and there is a problem that a lot of heat is generated due to the power loss due to the increase of the power consumption.

As shown in FIG. 1B, the conventionally developed to improve the light efficiency has a meandering shape of the discharge channel constituting the discharge space. Since the discharge channel has one discharge space, a large number of discharge currents exist in the discharge channel. Flows and the light efficiency increases to some extent.

However, such a fluorescent lamp causes a problem that the driving voltage increases and the leakage current increases as the discharge start voltage increases due to a long discharge channel. In addition, recently, as the liquid crystal display and the backlight device have been enlarged, flat fluorescent lamps having meandering discharge channels have a problem in that they cannot be commercialized because the length of the discharge channels increases rapidly.

In order to improve the light efficiency of such a conventional flat fluorescent lamp and to minimize the non-light-emitting area to obtain luminance uniformity, the applicant of the present invention discloses Korean Patent Publication No. 2002-0072260 (2002.09.14) `` Lamp assembly using a flat lamp '' Patent Publication No. 2004-0014037 (February 14, 2004) 『Platform Lamp and Lamp Assembly Using the Same』, Patent Publication No. 2004-0013020 (2004.02.11) 『Backlight Unit Using Flat Lamp』, Patent Publication 2004 -0004240 (January 13, 2004) has filed a technology related to a flat lamp, such as a "flat lamp and a backlight unit using the same". The above patents all relate to improvement of the electrode.

Accordingly, the applicant of the present invention has completed the present invention in which the structure of the discharge space is improved in order to improve the luminous efficiency and appearance characteristics during a series of development processes for the flat fluorescent lamp.

The present invention has been proposed to solve the problem of lowering the luminous efficiency and luminance uniformity of the conventional flat fluorescent lamp.

First, the present invention provides a flat fluorescent lamp in which the width of the partition wall forming the discharge channel of the discharge space is differentiated at the portion where the electrodes are arranged and other portions in order to minimize the non-light emitting area and maintain the optimum luminance uniformity. It aims to provide.

In addition, an object of the present invention is to provide an electrode form that can be discharged even at a low drive voltage (discharge start voltage) in order to reduce the power loss while increasing the visible light conversion efficiency even at a low drive voltage.

In order to achieve the above object, a flat fluorescent lamp according to the present invention comprises two substrates; A sealing member arranged along edges of the two substrates to seal a discharge space formed between the two substrates; Barrier ribs protruding side by side on the opposite surfaces of the two substrates to form a discharge channel to form a discharge space; And electrodes arranged on both end sides of the substrate in a form orthogonal to the partition wall to excite discharge gas filled in a discharge space formed between the two substrates, wherein each partition wall overlaps the electrode. And forming partitions in the effective light emitting region between the two electrodes so that the discharge channel width of the effective light emitting region is narrower than the discharge channel width of the non-light emitting region.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote members having the same function.

In FIG. 2, the flat fluorescent lamp 20 of the present invention is provided with two substrates 21 and 23 along the edges of the two substrates to seal the discharge space formed between the two substrates with the outside. (25).

The partition wall 30 is formed on one of the two substrates 21. The substrate on which the partition wall 30 is formed is generally referred to as a rear substrate and the other 23 is referred to as a front substrate. However, as described with reference to FIG. 5C in the specification of Patent Publication No. 2004-0004240, the partition 30 may be formed symmetrically on both substrates as necessary. Therefore, the present invention is not limited by the shape of the formed substrate of the partition wall. However, hereinafter, for the sake of convenience of description, the partition 30 is formed by referring to the rear substrate 21 and the other to the front substrate 23.

A lower layer of the back substrate 21 may be coated with a reflective layer prepared by mixing a glass with a white ceramic material composed of main components such as Al ₂ O ₃ , TiO ₂ , WO _3, and the like.

The partition wall 30 may be formed on the rear substrate 21 by sandblasting, laser processing, or grinding. In addition, the substrate may be softened by heating and then molded by pressing or vacuum adsorption, or may be manufactured by applying a sealing frit by applying a sealing frit to the height of the partition wall and applying heat bonding. The cross-sectional shape of each partition wall shown may be a quadrangular shape or a trapezoidal phase-neutral light shape such as that of FIG. 1A, and the present invention is not limited thereto.

The shape of the partition wall 30 constituting the core of the present invention, as can be seen more clearly in the plan view of Fig. 3b, the non-light-emitting area (N) (hatched portion that overlaps the electrode at both ends provided with the electrodes 40a, 40b The barrier ribs in the coarse thick dashed-dotted line form a narrow narrow portion 33, and the wider expansion in the effective light emitting region L (see inside the hollow thickened dashed line) between the electrodes 40a and 40b. Part 31 is achieved. Due to the shape of the partition wall 30, the discharge channel forming the discharge space 50 formed by the partition wall includes the narrow channel 51 corresponding to the expansion part 31 and the expansion channel 53 corresponding to the narrow part 33. ).

On the other hand, in the fluorescent lamp 20 according to the present invention, a plurality of channels formed in parallel by the partition wall has a connecting channel 55 formed on a side thereof to form a single discharge space by having a meandering shape connected to each other. In order to improve the vacuum exhaust speed of the fluorescent lamp and to smoothly diffuse the mercury 29 as the excitation source, a large discharge current flows in the discharge channel, thereby increasing the light efficiency.

In general, in the discharge channel having a meandering shape, the width of the connection channel 55 is preferably formed to be 5 mm or less, since the discharge may become unstable if the width of the connection channel is too large.

Furthermore, the connecting portion 35 connecting the expansion portion 31 and the narrow portion 33 of the partition 30 located in the effective light emitting region L may have a gentle width, as shown in FIG. 4. Having a shape is advantageous for the formation of a stable plasma.

The reason for developing the fluorescent lamp 20 having the discharge channel consisting of the partition wall 30 having such a structure, and thus, the narrow channel 51 and the expansion channel 53 is as follows. Is due.

In order to generate a uniform and stable discharge in the flat fluorescent lamp, the width of the discharge channel between the two partition walls is preferably formed in the range of 3 to 12 mm and the height of 2 to 5 mm. If the cross-sectional area of the discharge channel is too narrow, the discharge voltage becomes unstable as the driving voltage rises. On the other hand, if the cross-sectional area of the discharge channel is too large, the driving voltage is lowered, but the discharge plasma is not formed through the entire area of the channel cross section. This is because there is a problem in that the light emitting part does not occur in the entire discharge channel, thereby partially causing dark areas.

In addition, according to the experiments of the present inventors, the smaller the cross-sectional area of the discharge channel, the higher the discharge efficiency, and the larger the cross-sectional area, the lower the discharge efficiency, the cause is determined by the influence of the difference in current density. In other words, the higher the current density, the higher the brightness.

Therefore, it can be seen that it is important to provide an appropriate cross-sectional area of the discharge channel for uniform brightness.

However, in the case of the dielectric barrier discharge using an external electrode as in the conventional flat lamp structure, in order to control the discharge current, the area of the electrode that surrounds the discharge space is important. When the discharge channel is narrowed, the area of the electrode is also reduced to obtain an appropriate current. You do not get, and eventually you do not get the desired current density value.

In this case, it can be conceived that the problem can be solved at once by varying the width of the discharge space, that is, the effective light emitting area different from the region where the electrodes are arranged like the discharge channel structure. In other words, the width of the partition wall provided in the effective light emitting space where the visible light is generated by the discharge is increased and the width of the partition wall of the electrode space covered by the external electrode is narrow, so that the area of the discharge electrode is large even though the cross-sectional area of the discharge space is small. In the case of maintaining, both desired luminous efficiency and electrode area can be obtained.

When the fluorescent lamp having the structure of the discharge channel is configured, the width of the discharge electrode can be narrowed while the width of the strip-shaped rectangular discharge electrode can be kept the same and the electrode area covering the discharge channel can be maintained even in the aspect of electrode structure improvement. The width of the area covered by the electrode, that is, the non-light emitting area can be reduced, thereby improving the appearance of the LCD product.

At this time, it is preferable to narrow the width of the narrow portion 33 of the partition 30 positioned in the electrode space to 2 mm or less to secure the electrode area as much as possible.

Next, in FIG. 2, external ends 40a and 40b connected to a power source and an inverter are provided at both ends of the lower side of the rear substrate 21. In particular, the external electrodes 40a and 40b are rectangular external electrodes having a width equal to the length of the extension part 33 of the partition wall.

In the flat fluorescent lamp having a meandering discharge channel according to the present invention, an electrode structure provided for uniform light emission is also very important. In other words, the flat fluorescent lamp can be uniformly emitted only when the discharge start voltage is lowered to generate uniform and stable discharge for uniform emission.

In order to reduce the discharge start voltage (driving voltage), a method of shortening the distance between the electrodes is used. As the width of the discharge electrodes increases, there is a problem that the non-emitting region increases, so that the width of the rectangular discharge electrodes is maintained appropriately, and the two discharges It is desirable to provide an auxiliary electrode having a greatly reduced distance between electrodes between the electrodes to lower the discharge start voltage.

3A and 3B, the auxiliary electrodes 41a and 43a and 41b and 43b (see inside the thick one-dot line in FIG. 3B) and the main electrodes 40c and 40d provided at both ends of the upper surface of the front substrate 23 are shown in FIGS. A perspective view and a schematic plan view of the same flat fluorescent lamp is shown.

The auxiliary electrodes 41a, 43a, 41b, 43b may be separately connected to a power source, but as shown in the thick one-dot chain line of the main electrodes 40a, 40b (FIG. 3B) by the connection lines 45a, 45b. Reference).

In the drawing, the auxiliary electrodes 41a, 43a, 41b, 43b are located in the effective light emitting area L, and the width thereof is made equal to or slightly smaller than the width of the partition wall. If the widths of the auxiliary electrodes 41a and 43a and 41b and 43b are made too wide, the discharge current between the auxiliary electrodes increases to increase the power consumption, and also blocks visible light emitted to the outside of the front substrate to prevent the flat fluorescent lamp. It acts as a factor that lowers the brightness, and the discharge through the main electrodes 40a and 40b should be the main to form a relatively long plasma column, which increases the efficiency of the discharge. For losing. Therefore, it is desirable to keep the width of the auxiliary electrode as thin as possible.

The lamp assembly having the flat fluorescent lamp of the present invention having such an electrode structure is first connected to the main electrodes 40a and 40b when low power is supplied from the inverter connected to the discharge electrode and the conducting wire during driving. In the narrow channel 51 between the opposing auxiliary electrodes 41a and 43a and the auxiliary electrodes 41b and 43b, a preliminary discharge or an auxiliary discharge occurs to form ions or electrons. As a result, the total discharge is generated between the main electrodes 40a and 40b and 40c and 40d by the ions or charges formed in advance. The ultraviolet rays generated by the discharge generate vacuum ultraviolet rays such as 254 nm when mercury is used as the excitation source and 173 nm when xenon gas is used, and the vacuum ultraviolet rays reach the phosphor layer 27 coated on the surface of the discharge channel. The phosphor layer 27 is excited by vacuum ultraviolet rays and then transitions to a ground state to generate visible light. Visible light passes through the front substrate and passes through the diffusion material located on the upper surface of the lamp to become scattered light. When the additional light passes through the laminated prism material, light having a constant direction is radiated to the outside.

As described above, the planar fluorescent lamp according to the present invention can reduce the width of the electrode while obtaining a desired current density through the barrier narrow portion and the barrier expansion portion of the effective light emitting region in the non-light emitting region overlapping the portion where the electrode is installed. Optimum luminous efficiency can be maintained while minimizing the area of the non-emission region overlapping with the electrode.

In addition, the present invention includes a main electrode of a wide non-light emitting region and an auxiliary electrode of a relatively narrow emitting region, which can be discharged even at a low driving voltage, and can reduce power loss while increasing visible light conversion efficiency. .

In the above description, the bulkhead is described with respect to the flat fluorescent lamp, and other conventionally known techniques are omitted, but those skilled in the art will naturally be able to infer and deduce this.

In addition, in the above description of the present invention with reference to the accompanying drawings, a flat fluorescent lamp having a specific shape and structure was described mainly, but the present invention can be variously modified and changed by those skilled in the art, such variations and modifications of the present invention It should be interpreted as being within the scope of protection.

1A is a cross-sectional view showing a lamp assembly in which a conventional flat fluorescent lamp is used;

Figure 1b is an exploded perspective view of a conventional flat fluorescent lamp,

2 is an exploded perspective view of a flat fluorescent lamp according to the present invention;

3A and 3B are an exploded perspective view and a schematic plan view of a flat fluorescent lamp having a different arrangement of electrodes;

4 is a schematic view of the connection portion of the partition wall.

<Description of the symbols for the main parts of the drawings>

21: rear substrate 23: front substrate

25 sealing member 27 phosphor layer

29: here circle 30: bulkhead

31: Expansion 33: Narrow

35: connection part 40a, 40b, 40c, 40d: main electrode

41a, 43a, 41b, 43b: auxiliary electrode 50: discharge space

51: narrow channel 53: expansion channel

55: connecting channel L: emitting area

N: non-emitting area

Claims (7)

Two substrates; A sealing member arranged along edges of the two substrates to seal a discharge space formed between the two substrates; Barrier ribs protruding side by side on the opposite surfaces of the two substrates to form a discharge channel to form a discharge space; And Comprising an electrode arranged on both ends of the substrate in a form orthogonal to the partition wall to excite the discharge gas filled in the discharge space formed between the two substrates, The barrier ribs form a narrow portion in the non-light emitting region overlapping with the electrode and an extension portion in the effective light emitting region between the two electrodes, so that the discharge channel width of the effective light emitting region is narrower than that of the non-light emitting region. Fluorescent lamps. The method of claim 1, And a discharge channel formed by the barrier ribs is connected to each other in a meandering form by a connection channel. The method of claim 1, The partition wall is a flat fluorescent lamp having a shape in which the width of the connecting portion is located in the effective light emitting area and connecting the narrow portion and the expansion portion is expanded gently. The electrode according to any one of claims 1 to 3, wherein the electrode And a rectangular external electrode having a width equal to the length of the narrow portion of the partition wall. The electrode according to any one of claims 1 to 3, wherein the electrode A main electrode arranged to be biased at both ends of the substrate; The flat fluorescent lamp is arranged at a predetermined distance from the main electrode, characterized in that made of one or more auxiliary electrodes having a width narrower than the width of the main electrode. The method of claim 5, wherein the main electrode And a rectangular external electrode having a width equal to the length of the narrow portion of the partition wall. The method of claim 5, The auxiliary electrode is a flat fluorescent lamp, characterized in that arranged in the expansion portion of the partition wall.