Backlight unit for test device of LCD panel

A backlight unit for a test device of an LCD panel is disclosed. The backlight unit includes: a chamber enclosing a predetermined space, the chamber being provided with a plurality of through holes formed around the chamber perimeter to allow air flow between the interior and exterior of the chamber; a backlight provided in the chamber to emit a light to an LCD panel positioned in the chamber; and a plurality of circulating fans provided in the chamber to circulate air inside the chamber.

This application claims the benefit of Korean Patent Application No. 10-2005-0081403, filed on Sep. 1, 2005, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a test device for a liquid crystal display (LCD) panel, and more particularly, to a backlight unit having increased lifetime for an LCD panel test device.

2. Discussion of the Related Art

One type of test device of the related art for a liquid crystal display (LCD) panel allows a naked eye evaluation of whether the LCD panel is bad or good.

FIGS. 1 and 2illustrate a related art test device for an LCD panel.

As shown inFIGS. 1 and 2, the related art test device for an LCD panel includes a tester2and a loading/unloading unit7. The tester2is arranged at one side of a main body1to test an LCD panel10. The loading/unloading unit7is arranged at one side of the tester2, and receives and stores an LCD panel10to be tested.

The related art test device of the LCD panel further includes a carrier9arranged to be movable in left and right directions to carry the LCD panel10from the loading/unloading unit7to the tester2and vice versa.

The tester2includes a probe unit3and a work table4. The work table4contacts the LCD panel10with the probe unit3and supplies a light source. The work table4includes a polarizing plate4aand a backlight4b. A moving stage5is arranged at the rear of the work table4, and serves to align the work table4with respect to the probe unit3and to move the work table4into contact with the probe unit3.

The loading/unloading unit7is provided with a sub table8that tilts the LCD panel10carried from a loader (not shown) at a predetermined angle (for example, 60°).

In addition, a microscope6is arranged at the front of the tester2. The microscope may be moved in all directions. The microscope6serves to allow a worker to perform a more detailed inspection of the LCD panel10when a defect is found in the LCD panel using the naked eye.

A test process using the related art test device for an LCD panel will now be described in brief.

First, the LCD panel10is transferred from the loader of the loading/unloading unit7to the sub table8. The sub table8is tilted at a predetermined angle and the LCD panel10is transferred to the carrier9. The carrier9carries the LCD panel10to the tester2. When the LCD panel10to be tested is positioned in the tester2, the moving stage drives the work table4forward and the LCD panel10is fixed to the carrier9using a vacuum. A pad (not shown) of the fixed LCD panel10is electrically connected to a lead pin (not shown) of the probe unit3.

Once the LCD panel10is electrically connected with the probe unit3, a predetermined image signal is applied through the probe unit3while a lamp of the backlight4bis varied using various patterns provided by a pattern generator. The pattern generator is an external image signal input device. The worker can identify a defect of the panel by viewing the displayed pattern from the LCD panel10with the naked eye.

However, the related art test device of the LCD panel has the following problems.

First, in the related art test device of the LCD panel, a cold fluorescent lamp (CFL) or a cold cathode fluorescent lamp (CCFL) is used as the backlight4b. However, these types of backlight4bhave a problem in that frequent blinking on and off these lamp types rapidly decreases the lifetime of the lamp. The shortened lifetime results in the backlight4bhaving to be frequently replaced increasing the cost of operating the tester.

In addition, the lifetime of the backlight4bis decreased due to heating of the backlight4bby heat generated during operation of the backlight4b.

As the light source nears the end of its life, the light source may fail to illuminate particular portions of the LCD panel (for example, corner portions) during a test of the LCD panel. As a result, a defect in the particular portion of the LCD panel may not be effectively detected.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a backlight unit for a test device of a liquid crystal display (LCD) panel, which substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An advantage of the present invention is to provide a backlight unit for a test device of an LCD panel, in which heat generated by emission of the backlight is removed to increase the lifetime of the backlight unit.

Another advantage of the present invention is to provide a backlight unit for a test device of an LCD panel, in which a light source is uniformly supplied to the LCD panel to prevent brightness deviations from occurring.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a backlight unit for a test device of an LCD panel includes: a chamber having a predetermined space therein, provided with a plurality of through holes formed around the chamber perimeter to communicate between a space inside chamber space and a space exterior to the chamber; a backlight provided in the chamber to emit a light to an LCD panel positioned in the chamber; and a plurality of circulating fans provided in the chamber to circulate air inside the chamber.

In another aspect of the present invention, a backlight unit for a test device of an LCD panel includes: a chamber having a predetermined space therein; a plurality of high-brightness LEDs provided inside the chamber to emit a light to the LCD panel; a PCB substrate packaged with the respective high-brightness LEDs; and a refrigerant pipe provided inside the chamber to flow a refrigerant of a low temperature therein.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

A backlight unit for a test device of a liquid crystal display (LCD) panel according to embodiments of the present invention will be described with reference toFIGS. 3 to 13.

FIGS. 3 and 4are an exploded perspective view and a side sectional view illustrating a backlight unit for a test device of an LCD panel according to a first embodiment of the present invention.

As shown inFIGS. 3 and 4, the backlight unit for a test device of an LCD panel according to the first embodiment of the present invention includes a chamber410, a backlight420, and a plurality of circulating fans430.

The chamber410has a rectangular box shape having a predetermined volume therein, with an open top surface. The chamber410is provided with a plurality of through holes411along the perimeter of the chamber410. An inner space of the chamber410communicates with its outer space through the through holes411.

The through holes411may be formed along the entire of the perimeter of the chamber410, along two opposing portions of the perimeter, or along one portion of the perimeter.

Alternatively, the chamber410may have a cylindrical shape or a polygonal box shape having a plurality of corners.

A backlight420is provided inside the chamber410. The backlight420comprises a plurality of lamps that emit light to illuminate the LCD panel10.

The backlight420may be provided at an upper space inside the chamber410.

When the backlight420is provided at an upper space inside the chamber410, the space at the lower interior of the chamber410may be maintained empty to facilitate the flow the air through inside the chamber410.

In addition, the backlight420may include of any one of cold fluorescent lamps (CFLs), cold cathode fluorescent lamps (CCFLs), external electrode fluorescent lamps (EEFLs), and high-brightness LEDs.

InFIGS. 3 and 4, the backlight420is illustrated as comprising a plurality of high-brightness LEDs421.

By employing high-brightness LEDs as the backlight420, the lifetime of the backlight unit does not decrease with frequent blinking on and off the backlight420, minimizing brightness deviation in regions such as the corner of the LCD panel.

Each high-brightness LED421is packaged on a PCB substrate422, and the PCB substrate422is mounted in the chamber410. The PCB substrate422is designed to support each high-brightness LED421in the chamber410and to provide various signals and power to each high-brightness LED421.

The circulating fans430are provided inside the chamber410, and may be arranged to vent the air outside the chamber410toward the inside of the chamber410through the through holes411.

It is to be understood that the circulating fans430may be arranged to vent the air inside the chamber410toward the outside of the chamber410. Alternatively, some circulating fans430may be arranged to vent the air outside the chamber410toward the inside of the chamber410while other circulating fans430are arranged to vent the air inside the chamber410toward the outside of the chamber410. The number circulating fans430may be varied.

A circulating fan430may be provided for each through hole411. Each through hole411may have a diameter substantially identical with an air flow opening of a respective circulating fan430.

Hereinafter, the operation of the aforementioned backlight unit according to the first embodiment of the present invention including its air circulating operation will be described.

First, when the backlight unit is controlled to test the LCD panel10, each high-brightness LED421is operated to emit light.

The light emitted from each high-brightness LED421is irradiated into the LCD panel10. A signal for displaying various patterns is supplied to the LCD panel10, and as a result, various images are displayed in the LCD panel10.

While the high-brightness LED421is emitting light, each of the circulating fans430is driven to circulate air.

Air from outside of the chamber410is vented into the chamber410through through holes411to circulate air onto each high-brightness LED421and onto the PCB substrate422inside the chamber410.

The circulating air provides a cooling effect minimizing damage to the various circuits on the PCB substrate422due to heat generated by the high-brightness LEDs421.

Further, when the aforementioned backlight420comprises high-brightness LEDs421, the lifetime of the backlight420is preserved even when the backlight are blinked frequently to test the LCD panel10or due to other demands to blink the LEDs421.

FIGS. 5 and 6illustrate a backlight unit according to a second embodiment of the present invention.

As shown inFIGS. 5 and 6, the backlight unit according to the second embodiment of the present invention includes a chamber410, a backlight420, circulating fans430, and a heat-radiating member440.

The second embodiment of the present invention differs from the first embodiment in that a heat-radiating member440is further provided in the backlight unit.

The cooling effect of air circulating on the PCB substrate422is increased when air from outside the chamber410, which is vented into the chamber410, makes effective contact with the PCB substrate422. In the second embodiment of the present invention, the heat-radiating member440is used to increase the effective contact area between the circulated air and the PCB substrate422.

Hereinafter, the construction of the second embodiment is described in detail.

The chamber410, the backlight unit420and the circulating fans430of the backlight unit according to the second embodiment of the present invention are the same as those of the backlight unit according to the first embodiment of the present invention.

In other words, the high-brightness LEDs421of the backlight420are packaged on the PCB substrate422inside the chamber410. A plurality of through holes411are formed along the perimeter of the chamber410. Each of the through holes411may be provided with the circulating fan430.

The heat-radiating member440is additionally provided along a rear surface of the backlight420in a lower surface inside the chamber at the base of the PCB substrate422on which the high-brightness LED421are packaged.

One surface of the heat-radiating member440is in contact with the bottom of the PCB substrate422to facilitate the conduction of heat from the PCB substrate422. The other surface of the heat-radiating member440is a heat sink including a plurality of radiating fins441. The radiating fins441may be formed on a single body with the radiating fins441spaced apart at predetermined intervals.

Alternatively, the heat-radiating member440may be formed of either a heat sink having a plurality of peaks and recesses or of a plurality of thin plates formed at predetermined intervals.

Each of the through holes411formed along the perimeter of the chamber410has a diameter sufficiently large to allow the air space near the heat-radiating member440to communicate with the outside of the chamber.

Hereinafter, the operation of the aforementioned backlight unit according to the second embodiment of the present invention including its air circulating operation will be described.

First, when the backlight unit is controlled to test the LCD panel10, each high-brightness LED421is operated to emit light.

The light emitted from each high-brightness LED421is irradiated into the LCD panel10. As a result, various images are displayed in the LCD panel10.

While the high-brightness LEDs421emit light, each circulating fan430is driven to circulate air.

The heat-radiating member440provided inside the chamber410conducts heat generated during the emission of light by the high-brightness LEDs421away from the PCB substrate422.

Air from outside of the chamber410is vented into upper and lower spaces inside the chamber410through each through hole411as each circulating fan430is driven. The air vented into the upper space inside the chamber410circulates onto each high-brightness LED421and picks up heat generated by the high-brightness LEDs421. In addition, the air vented into the lower space inside the chamber410circulates over the heat-radiating member440while flowing in the lower space inside the chamber410.

The cooling effect of air circulating onto the high-brightness LED421and onto the PCB substrate mitigates damage to various circuits on the PCB substrate422due to heat generated by emission the high-brightness LED421.

FIGS. 7 and 8illustrate a backlight unit according to a third embodiment of the present invention.

As shown inFIGS. 7 and 8, the backlight unit according to the third embodiment of the present invention includes a chamber410, a backlight420, and a refrigerant pipe450.

In the third embodiment of the present invention, the refrigerant pipe450is provided inside the chamber410to facilitate cooling of the inside of the chamber410of the backlight unit. The refrigerant pipe450is designed such that a low temperature refrigerant flows therein.

In other words, the third embodiment of the present invention provides a reduced temperature inside the chamber410due to the flow of refrigerant of a low temperature within the refrigerant pipe450.

Hereinafter, the third embodiment of the invention will be described in more detail.

The chamber410and the backlight unit420of the backlight unit according to the third embodiment of the present invention are the same as those of the backlight unit according to the first embodiment.

In other words, the high-brightness LEDs421of the backlight420are packaged on the PCB substrate422inside the chamber410. A plurality of through holes411are formed along the perimeter of the chamber410.

The refrigerant pipe450is provided along a rear surface of the backlight420inside the chamber410. That is, the refrigerant pipe450is provided below the PCB substrate422on which the high-brightness LED421are packaged. The refrigerant pipe450may have a multi-stage bent shape (zigzag shape). The low temperature refrigerant flows inside the refrigerant pipe450.

The refrigerant pipe450is connected to a separate cooling cycle device460provided outside the chamber410. The cooling cycle device460, as shown inFIG. 8, includes a compressor461for compressing a refrigerant, a condenser462for condensing the compressed refrigerant, an evaporator464for expanding the condensed refrigerant, and a heat exchanger464for removing heat released during expansion of the refrigerant. The refrigerant pipe450constitutes the heat exchanger464. The cooling cycle device460may be provided separately from the backlight unit.

The refrigerant pipe450may be positioned with its top surface attached to or in close proximity to the bottom of the PCB substrate422.

The refrigerant pipe450may be provided at intervals between high-brightness LEDs421inside the chamber410.

The temperature inside the chamber410is reduced by the flow of low temperature refrigerant within the refrigerant pipe450even while heat is generated during light emission by the high-brightness LEDs421during use of the backlight unit. By placing the PCB substrate422in direct thermal contact with the refrigerant pipe450, damage to circuits on the PCB substrate due to heat may be avoided.

As shown inFIG. 9, the backlight unit according to the third embodiment of the present invention may further include circulating fans430as described in the first embodiment of the present invention.

In addition, as shown inFIG. 10, the backlight unit according to the third embodiment of the present invention may further include a heat-radiating member440as provided in the second embodiment of the present invention.

When the backlight unit according to the third embodiment of the present invention further includes a heat-radiating member440, the refrigerant pipe450may be positioned to pass through each radiating fin441of the heat-radiating member440so that the refrigerant within the refrigerant pipe450can remove heat through heat exchange with the air inside the chamber410through the heat-radiating member440.

The backlight unit according to the third embodiment of the present invention may include both circulating fans430and the heat-radiating member440.

When the backlight unit according to the above described embodiments of the present invention is operated, the high-brightness LEDs421constituting the backlight420emit light onto the LCD panel, with the light being diffused at a predetermined lamp angle (for example, 70°).

When the light is diffused at the predetermined lamp angle, the light illuminates the inner portions of the LCD panel under tested is of a relatively high intensity due to overlapping of the illumination from more than one LED. By contrast, since the light illuminating outer of the LCD panel is simply diffused from a single LED without overlap, the illumination intensity at the outer portions of the LCD panel is relatively low.

Therefore, brightness deviations occur between the inner and outer portions of the LCD panel.

As shown inFIG. 12, a relatively small sized LCD panel11(for example, a panel 32 inches in length or less) is uniformly supplied with the light, and the whole portion of the LCD panel11may be displayed bright. By contrast, for a relatively large sized LCD panel12(for example, a panel 42 inches in length) outer portions of the LCD panel are not sufficiently supplied with the light, resulting in brightness deviations occurring between the inner and outer portions of the LCD panel12.

The brightness deviations may result in defects of a specific pattern or various foreign matter not being effectively detected.

In the fourth embodiment of the present invention, as shown inFIG. 13, a lens unit470is further provided to prevent brightness deviations from occurring. The lens unit470according to the fourth embodiment of the present invention is provided at each high-brightness LED421to allow the light emitted from each high-brightness LED421to be collimated into a directional beam.

The lens unit470may comprise an optical lens.

The aforementioned lens unit470collimates the light emitted from each high-brightness LED421to be emitted to the LCD panels11and12into a direction beam, so that the light can uniformly be supplied to the entire portion of each of the LCD panels11and12. The uniform supply of light to the LCD panels11and12prevents brightness deviations occurring between different portions of the LCD panels11and12.

Alternatively, as shown inFIG. 14, the lens units470may be provided at only selected high-brightness LEDs of the light units. For example, the lens units470may be provided only at high-brightness LEDs located along the outer portions of the PCB substrate422.

The structure of the backlight unit according to the fourth embodiment of the present invention may be applied to the structures of the backlight unit according to the first to third embodiments of the present invention. Alternatively, the structure of the backlight unit according to the fourth embodiment of the present invention may be provided separately from the structures of the backlight unit according to the first to third embodiments of the present invention.

It is to be understood that the backlight unit for a test device of an LCD panel according to the present invention is a useful invention in which various modifications may be made as occasions demand.

As described above, the described embodiments of the backlight unit for a test device of an LCD panel according to the present invention have the following advantages.

First, when the backlight unit comprises high-brightness LEDs, it is possible to prevent lifetime of the backlight from decreasing with frequent blinking on and off of the backlight, reducing the cost associated with replacing the backlight.

Secondly, by providing the backlight unit with an air circulating structure, it is possible to preserve lifetime of the backlight even though a great quantity of heat is generated inside the chamber during light emission from the backlight.

Further, although the PCB substrate provided with the high-brightness LEDs is sensitive to heat generated during light emission by the high-brightness LEDs, by removing heat removed from the PCB substrate using the circulating fans, the heat-radiating member, or the low temperature refrigerant, it is possible to avoid damage to the various circuits on the PCB substrate.

Finally, since the light emitted from the backlight is collimated into a directional beam, light is uniformly supplied to the LCD panel, thereby obtaining uniform brightness over the whole portions of the LCD panel. As a result, the LCD panel can be more effectively tested for pattern defects or various foreign matter in the LCD panel.