KR20010044259A - Discharge lamp and the back light unit applying the same - Google Patents

Abstract

PURPOSE: A back light unit employing discharge lamps is provided to not only shorten the time of stabilizing the luminescence and to increase the luminescence, and thus reducing the number lamps, but also to reduce the part not producing the light so miniaturize the unit. CONSTITUTION: In the back light unit employing discharge lamps, a tubelike lamp(11) is sealed with discharge gas injected in. The first and second electrodes(12,13) are formed on both sides of the tubelike lamp(11). A getter electrode(15) is formed inside the lamp(11) on one of the electrodes(12,13) at least. On the side of the getter electrode, a device limiting the position of the getter electrode(19) is formed in the end of the lamp(15). The device(19) is formed so that the surface makes a curve or a bidding. However, the curve or the bidding should not interfere with dielectric barrier discharge.

Description

Discharge lamp and the back light unit applying the same}

The present invention relates to a backlight unit, and more particularly, to a discharge lamp capable of implementing high brightness and low power consumption by installing electrodes outside the tube and a backlight unit employing the same.

In general, a display is classified into a light emitting type and a light receiving type. The light emitting type includes a cathode ray tube, a plasma display panel, an electroluminescent device, a fluorescent display device, a light emitting diode, and the like. The light receiving type is a liquid crystal display.

Among them, since the liquid crystal display itself emits light and does not form an image, and light is incident on the outside to form an image, there is a problem in that an image cannot be observed in a dark place.

In order to solve this problem, a back light unit is installed on the back of the liquid crystal display to irradiate light. Accordingly, an image can be realized even in a dark place.

Background Art [0002] Cold cathode fluorescent lamps (CCFLs) and flat plate fluorescent lamps incorporating phosphor-coated upper and lower substrates are widely used for backlight units. The arrangement of the cold cathode fluorescent lamp is divided into an edge light method using a plastic light guide and a direct light method overlapping on a plane according to the arrangement of the light source on the display surface. can do.

The fluorescent lamp used for the backlight includes an internal electrode type and an external electrode type. In the case of the internal electrode type, electrodes are installed inside both ends of the tube, and an insulating clamp holder having a lead wire connected to the electrode is provided. . In the internal electrode type, the darkening of the electrode causes blackening of the electrode due to deterioration of the electrode during driving. These dark portions are each 15 mm at both ends of the fluorescent lamp.

An example of an external electrode fluorescent lamp used in such a backlight unit is disclosed in Korean Patent Publication No. 2000-037279, Korean Patent Application Nos. 2000-64011, 2000-64013, and 2000-64014. .

The disclosed fluorescent lamp is formed by forming a phosphor layer in a sealed tubular tube and having electrodes provided on both outer peripheral surfaces of the tube.

The fluorescent lamp generates magnetic lines from trace amounts of Hg distributed in the tube through the anode discharge of the tube, and excites the phosphor layer by the ultraviolet rays to emit visible light, and the visible light is induced directly or through a reflecting plate. To exit. On the other hand, the surface light source device using the fluorescent lamp is formed with a plurality of channels in which the lamp is mounted on the light guide plate, and the upper and lower surfaces of the light guide plate is provided with a diffuser plate and a reflecting plate, respectively.

However, in the fluorescent lamp as described above, since electrodes are provided on both outer circumferential surfaces of the tube, a non-light emitting area is generated by the electrode, and the non-light emitting area is a dead space at the edge portion of the backlight unit using the fluorescent lamp. ) Is inevitable. This dark part places a lot of constraints in miniaturizing the backlight unit.

In particular, when the electrode is installed at both ends of the tube or an electrode using a cap is used, an increased length of the electrode is required compared to a fluorescent lamp in which a conventional electrode is embedded in the tube in order to obtain higher luminance. Will be increased. In addition, in the case of the external electrode type fluorescent lamp, the contact area between the electrode and the dielectric, ie, the tube, required to rise to the internal temperature (about 40 ° C.) for smooth dielectric barrier discharge and mercury vaporization in the tube. It depends. However, in the conventional external electrode fluorescent lamp, if the width of the positive electrode is made too wide, the area of the dark part which is advantageous to increase the temperature inside the tube is widened, and when the width is relatively narrow, it takes a lot of time due to the temperature rising and sufficient light emission. There is a problem that luminance cannot be obtained.

On the other hand, the external electrode discharge lamp as described above is a productive method for injecting a small amount of mercury into the tube in the exhaust gas and the injection of discharge gas in the state of being mounted inside the tube of the getter electrode impregnated with mercury. After completion, mercury activation and gettering through high frequency heating is performed, and the tube is sealed again to remove it. In this process, when the tube is sealed and cut again, there is a problem in that productivity and yield are deteriorated due to defects caused by cracks in the tube and defects caused by deterioration of discharge characteristics due to the generation of impurity gas in the tube during sealing. In addition, in the conventional discharge lamp, the mercury is generated in the tube due to the adsorption of the mercury on the phosphor layer or the reaction with the non-fluorine in the long-term use, the luminous efficiency is reduced.

The present invention is to solve the above problems, it is possible to shorten the stabilization time of the light emission luminance, to increase the light emission luminance, and to provide a discharge lamp that can reduce the occurrence of the dark portion when applied to the backlight. have.

Another object of the present invention is to provide a backlight unit capable of reducing the number of fluorescent lamps by increasing the luminance of light emission and reducing the area of the non-emission area.

1 is a cross-sectional view showing a discharge lamp according to the present invention,

2 is a cross-sectional view showing another embodiment of a discharge lamp;

3 and 5 are cross-sectional views showing another embodiment of a discharge lamp according to the present invention;

6 to 9 are perspective views showing an embodiment of a backlight unit using a discharge lamp,

10 is a graph showing a relationship between luminance and time according to the length of an electrode.

In order to achieve the above object, the discharge lamp of the present invention includes a tube in which both ends are sealed, electrodes installed on an outer circumferential surface of the tube to cause barrier discharge, and getter electrodes impregnated with mercury in one or both sides of the tube. It is characterized by including.

In the present invention, a phosphor layer is formed on the inner surface of the tube, and the getter electrode is floated. A getter electrode positioning means for defining the position of the getter electrode is provided at the end of the tube where the getter electrode is located. The getter electrode positioning means is formed by bending the outer peripheral surface of the tube to the inside.

Discharge lamps of another feature to achieve the object comprises a tube is sealed at both ends, and the electrode is provided at both ends of the tube to cause a dielectric barrier discharge, the length of the electrode in the longitudinal direction of the tube It is formed more than 20mm.

In the present invention, both ends of the tube in which the electrode is installed is made of the tube is bent at a predetermined angle with respect to the longitudinal direction, the inside of the getter electrode impregnated with mercury, at least one side of the inner or outer tube A phosphor layer excited by ultraviolet rays is formed.

Another feature of the present invention for achieving the above object is a tube that is closed at both ends, the external electrode is installed on one side of the tube to cause a dielectric barrier discharge and the other side of the tube is located inside the tube Including an internal electrode, characterized in that the length of the external electrode is formed to 10mm or more with respect to the longitudinal direction of the tube.

Both ends of the tube are bent to be inclined at a predetermined angle with respect to the longitudinal direction of the tube, and a getter electrode impregnated with mercury may be embedded therein. A phosphor layer excited by ultraviolet rays is formed on at least one side of the inner surface or the outer tube.

The backlight unit using the discharge lamp of the present invention is a tube having a phosphor layer formed on at least one side of the inner and outer sides, a discharge lamp having a length of 20 mm or more in the tube length direction of the electrode provided on the outer peripheral surface of both ends of the tube,

At least one fluorescent lamp is characterized by comprising a base member having a reflective film provided on the upper surface, and a diffusion plate provided on the base member to diffuse visible light emitted from the discharge lamp.

In the present invention, both edge portions of the tube on which the electrode of the discharge lamp is installed are inclined at a predetermined angle with respect to the longitudinal direction of the tube, and a getter electrode impregnated with mercury is installed inside the edge where the electrode is formed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows an embodiment of a discharge lamp according to the present invention.

As shown in the drawing, the discharge gas is sealed inside the tubular tube 11, and the first and second electrodes 12 and 13 are provided on the outer circumferential surfaces of both ends of the tube 11.

A getter electrode 15 is installed inside at least one end of both ends of the tube 11. A getter electrode positioning means 19 is provided at the end of the tube on which the getter electrode 15 is installed to define the mounting position of the getter electrode 15. The getter electrode positioning means 19 is formed by bending or beading the outer circumferential surface of the tube end along the outer circumferential surface. At this time, the curved portion or the beaded portion on the outer circumferential surface of the tub is formed to not interfere with barrier discharge.

In the discharge lamp, a phosphor layer 14 excited by ultraviolet rays generated by barrier discharge of the dielectric by the electrode may be formed on at least one side of the inner surface or the outer surface of the tube 11.

The ends 11a and 11b of the tube 11 on which the first and second electrodes 12 and 13 are formed have a length of the tube to prevent the end of the electrode forming portion in the effective light emitting region from acting as a dark portion. It may be bent at an angle to the direction (eg 90 °). The bending angle of the end portion of the tube 11 is not limited by the above-described embodiment, and may be installed at various angles according to the installation place and function of the fluorescent lamp.

2 shows another embodiment of a discharge lamp according to the present invention.

As shown in the figure, the inside of the tubular tube 11 is sealed with a discharge gas such as mercury injected therein, and the first and second electrodes 12 and 13 are installed on the outer circumferential surfaces of both ends of the tube 11. The length L1 of the electrodes 12 and 13 is formed to be 20 mm or more with respect to the tube length direction.

Meanwhile, as shown in FIG. 3, a getter electrode impregnated with mercury may be positioned in the end portions 11a and 11b provided with the first and second electrodes 12 and 13. 15 is floated with respect to the first and second electrodes 12 and 13. Naturally, the ends of the tubes on which the first and second electrodes are formed may be bent in order to prevent them from acting as arm portions of the discharge lamps.

Figure 4 shows another embodiment of the tube according to the present invention, at the end of the tube 11 is formed an enlargement 16 relatively larger than the diameter of the tube 11 and the electrode ( 17) (18) is provided, It is preferable that the length L2 of the tube length direction of this electrode is formed in 20 mm or more. The getter electrode may be installed in the extension 16.

5 shows another embodiment according to the present invention.

As shown in the drawing, there is a tube 21 filled with discharge gas therein, internal electrodes 22 and 23 which are respectively installed inside both ends of the tube and include lead wires, and the inner or outer surface of the tube 21. It includes a phosphor layer 24 provided on at least one side of the. Here, both ends 21a and 21b of the tube on which the internal electrodes 22 and 23 are installed are bent at a predetermined angle with respect to the longitudinal direction of the tube 21. Reference numeral 25 is a cap.

6 shows another embodiment of a discharge lamp according to the present invention.

Sealed in a state in which discharge gas such as mercury is injected into the inside of the tubular tube 40 shown, an outer electrode 41 is installed on one outer circumferential surface of the tube 40 and an inner electrode on the other side of the tube 40. A 42 is provided, and the internal electrode 42 extends from the outside of the tube to the inside of the tube 40 and is located inside the tube 40. Herein, the external electrode 41 installed outside the tube 40 has a length L3 of 10 mm or more in the longitudinal direction of the tube 40. In the discharge lamp, a phosphor layer 43 excited by ultraviolet rays generated by barrier discharge of the dielectric by the electrode may be formed on at least one side of the inner surface or the outer surface of the tube 40. Both ends of the tube 40 configured as described above may be bent at a predetermined angle to prevent the end of the electrode forming portion in the effective light emitting region from acting as a dark portion. In addition, a getter electrode impregnated with mercury may be mounted in a floating state in the tube 40 in which the external electrode 41 is formed.

And Figure 7 shows an embodiment of a backlight unit using a discharge lamp according to the present invention.

As shown, a base member 31 having a reflective surface 31a or a fluorescent surface formed thereon, a plurality of discharge lamps 10 disposed on the base member 31 at predetermined intervals, and the fluorescent lamp 10 and the base And a diffuser plate 32 disposed on the upper portion of the member 31. A prism sheet for improving focusing and straightness of light diffused through the diffuser plate 32 is disposed on the diffuser plate 32. ) And a protective film layer may be provided on the prism sheet to protect it.

Herein, the discharge lamp 10 may use the discharge lamp mentioned in the above embodiments. In particular, both ends of the tube 11 are bent in the longitudinal direction so that both ends 11a and 11b of the tube 11 provided with the first and second electrodes are positioned in parallel with the side surface of the base member 31.

In the above embodiment, in the case of the UV lamp that the phosphor layer is not applied to the inner surface or the outer peripheral surface of the fluorescent lamp may be formed of a separate phosphor layer on the lower surface of the light guide plate.

As shown in FIG. 8, the discharge lamp installed in the fluorescent lamp base member 31 may be installed such that both ends bent at 90 degrees of the tube 11 face upwards, or as shown in FIG. Both ends of the tube 11 are installed to be perpendicular to the base member 31 or vertically through the base member.

The surface light source device is not limited to the above-described embodiment and may be any structure as long as it has a structure using a fluorescent lamp in which both ends of the tube are bent.

Hereinafter, the operation of the fluorescent lamp and the surface light source device configured as described above will be described.

First, an AC or pulse waveform voltage is applied to the first and second electrodes 12 and 13 provided on the outer circumferential surface of the tube 11. When the voltage is applied in this way, the fluorescent lamp 10 has a capacitive coupling structure in which the first and second electrodes 12 and 13 are installed on the outer circumferential surface of the tube 11. Wall charges are charged inside.

The charged wall charges collide with mercury gas, which is the discharge gas injected into the discharge space of the discharge lamp 10, to generate ultraviolet rays. Ultraviolet rays generated during the discharge excite the phosphor of the phosphor layer 14 formed on the inner surface of the tube 11 and convert it into visible light. At this time, the current flows through the pipe wall where the first and second electrodes are located.

In particular, when the getter electrode 15 is provided at one side or both ends of the tube, the getter electrode 15 impregnated with mercury flows to the tube wall. As a result, a certain amount of secondary electrons are emitted from the first and second electrodes 12 and 13, and the discharge voltage is somewhat lowered. In addition, when the discharge lamp is used for a long time, mercury in the tube due to adsorption on the phosphor layer or reaction with impurities is reduced. This consumption of mercury may be partially compensated by the getter electrode 15. In addition, the getter electrode 15 may improve impurities life by adsorbing impurities generated during discharge.

The light irradiated from the discharge lamp 10 is diffused through the diffusion plate 32 as described above, and is reflected in one direction by the reflective film 31a. Subsequently, light is diffused through the diffusion plate 32, and the diffused light can be irradiated with a light receiving type display mounted on the upper surface of the surface light source device with dust collection and straightness via a prism sheet.

In the backlight device operated as described above, since both ends 11a and 11b of the tube 11 forming the discharge light lamp 10, that is, both ends 11a and 11b of the tube 11 on which the electrode is formed, the electrode is connected to the tube 11. It is possible to reduce the interference caused by the non-light emitting area generated by being provided on the outer circumferential surface. That is, as shown in Figs. 7, 8 and 9, the ends of the tubes 11 and 21 are installed in the direction parallel to the edge of the base member 31 or the diffusion plate. Since the base member 31 is vertically upwardly or vertically downwardly installed, the light emitting area can be minimized by the end portion of the tube 11 of the non-light emitting area. According to the experiments of the present inventors, when the diameter of the fluorescent lamp is 3 mm or less, the non-light-emitting area can be reduced by 80% or more compared with the conventional fluorescent lamp having a non-emitting area of 10 to 15 times the diameter of the irrespective of the screen size of the surface light source device.

Meanwhile, since the length L1 of the first and second electrodes 12 and 13 formed at the end of the tube is 20 mm or more with respect to the length direction of the tube, the tube for vaporization of mercury contained in the tube within a short time. The temperature can be raised and a luminance of 6000 cd / m 2 can be obtained.

The action as described above will be clearer through the following experiment.

Experimental Example 1

The inventors experimented the relationship between the length and the area of the first and second electrodes provided at both ends of the tube and the luminance, and obtained graphs as shown in Table 1 and FIG. 10.

Experimental conditions: diameter of fluorescent lamp; 2.6 mm, distance between electrodes; 320 mm, drive frequency; 46 kKz, drive voltage; 1.2 kV, measurement temperature; Room temperature

Electrode length (electrode area) time 5.0 minutes 10.0 minutes 15.0 minutes 20.0 minutes 25.0 minutes 30.0 minutes 10 mm 3215 3336 3407 3457 3488 3518 15 mm 4482 4598 4705 4812 4925 5037 20 mm 5610 5800 5903 5973 6014 6044 25 mm 6211 6376 6444 6482 6510 6523 30 mm 7176 7270 7317 7237 7347 7357

In the liquid crystal display field, luminance is typically evaluated within 30 minutes after voltage application. As shown in Table 1 and FIG. 10, it was found that the luminance was 6000 cd / m 2 or more within 25 minutes when the length of the electrode was 20 mm or more.

Experimental Example 2

The present inventors experimented the relationship between the length of the first and second electrodes provided at both ends of the tube, the diameter of the discharge lamp, and the brightness, to obtain Table 2 below.

Experimental conditions: distance between electrodes; 320 mm, drive frequency; 46 kKz, drive voltage; 1.2 kV, measurement temperature; Room temperature

As can be seen in Table 2, the luminance is high around the tube diameter of 2.0mm, which is high. If the electrode length is the same, the tube diameter is small, so the surface area of the electrode is small, so that the capacitance (C) value is small, but the current density is small. Since increases, the luminance change as a whole becomes small. However, the drawing brightness gradually decreases as the diameter of the tube increases. This is because, as the diameter increases for the same electrode length, the capacitance value increases, but the current density decreases. At this time, the surface temperature of the tube also increases relatively slowly compared to the small diameter, so if the diameter increases to 3.0 mm or more, the length of the electrode should be 20 mm or more to enable high luminance.

Therefore, the capacitance (C) value and the current density (r), which affect the brightness of the tube diameter of the discharge lamp, are related to the relationship between C ∝ (r) and current density ∝ (1 / (square of the tube radius)). In the case of the discharge gas and phosphor coating conditions of the discharge lamp having a tube diameter of 2 to 3 mm and the inverter driving them, the length of the electrodes at both ends of the discharge lamp is at least 20 mm when using dielectric barrier discharge. Only high brightness can be achieved.

The discharge lamp of the surface light source device has a getter electrode impregnated with mercury in the inner end of the tube with the electrode formed on the outer circumferential surface thereof. Since current flows, the temperature around the getter electrode rises relatively earlier than without the getter electrode, thereby shortening the stabilization time of luminance. In addition, the mercury is continuously released from the getter electrode and adsorbed to the fluorescent film layer to compensate for the consumption of mercury in the tube, thereby improving luminance maintaining characteristics, and secondary electron emission is generated at the getter electrode, thereby improving discharge efficiency.

Meanwhile, as shown in FIG. 6, in the discharge lamp in which the external electrode 41 is installed at one end of the tube 40 and the internal electrode 42 positioned inside the tube is disposed at the other end, the external electrodes are disposed at both ends of the tube. It has the advantage of minimizing the non-emitting area than the configuration installed. That is, when the external electrodes are provided at both ends as in the above embodiment, the capacitance of each discharge lamp is connected in series, and the capacitance at this time is (1 / C) = (1 / C1) + (1 / C2), Since C = (C1xC2) / (C1 + C2), if the electrode widths at both ends are the same (C1 = C2), the capacitance of the discharge lamp is C / 2. On the other hand, when the external electrode having the same electrode width is installed only on one side, the capacitance is twice as large as when the external electrode is installed at both ends, thereby increasing the power of the lamp twice. Therefore, when the external electrode is placed only on one side from the previous test results, it is necessary to have an electrode width of 10 mm or more rather than 20 mm.

The discharge lamp can replace the existing discharge lamp without changing the shape of the tube, and has the same electrical characteristics as the electrodeless type in terms of driving characteristics, thereby taking advantage of the discharge lamp having an electrode installed outside the tube. . In addition, since the internal electrode 42 installed on the other side of the tube acts advantageously to increase the temperature of the discharge lamp, it is possible to shorten the stabilization time of the brightness and to facilitate the exhaust and encapsulation process, thereby improving productivity.

As described above, the discharge lamp of the present invention and the backlight unit employing the same can reduce the non-light emitting area, can reduce the required amount of the discharge lamp due to high brightness, and can reduce the production cost.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (14)

A discharge lamp comprising a tube sealed at both ends and electrodes provided at both ends of the tube to cause dielectric barrier discharge. Discharge lamp, characterized in that the length in the longitudinal direction of the tube of the electrode is 20mm or more. The method of claim 1, A discharge lamp, characterized in that both ends of the tube on which the electrode is installed is bent inclined at a predetermined angle with respect to the longitudinal direction. The method of claim 1, And a getter electrode impregnated with mercury is inserted into at least one side of both ends of the tube on which the electrode is formed. The method of claim 1, Discharge lamp, characterized in that the phosphor layer applied to at least one side of the inner surface or the outside of the tube is provided, A backlight unit using the discharge lamp as claimed in claim 1. A tube having both ends sealed, an external electrode installed at one side of the tube to cause a dielectric barrier discharge, and an internal electrode installed at the other side of the tube, wherein the external electrode has a length Discharge lamp, characterized in that formed in more than 10mm with respect to the longitudinal direction of the tube. The method of claim 6, A discharge lamp, characterized in that both ends of the tube on which the electrode is installed is bent inclined at a predetermined angle with respect to the longitudinal direction. The method of claim 6, Discharge lamp, characterized in that the phosphor layer applied to at least one side of the inner surface or the outside of the tube is provided. The method of claim 6, Discharge lamp, characterized in that the getter electrode impregnated with mercury is inserted inside the tube end formed with the external electrode. A discharge lamp comprising a tube sealed at both ends, electrodes disposed on an outer circumferential surface of the tube to cause barrier discharge, and getter electrodes impregnated with mercury in one or both sides of the tube. The method of claim 10, A phosphor layer is formed on an inner surface of the tube, and the getter electrode is floated. The method of claim 10, And a getter electrode positioning means for defining a position of the getter electrode at an end of the tube where the getter electrode is located. The method of claim 12, The getter electrode positioning means is a discharge lamp, characterized in that the outer peripheral surface of the wing tube is curved inwardly. The method of claim 10, A backlight unit employing the discharge lamp.