Receiving module for a display device, display device including the same, and method thereof

A receiving module for a display device includes a receiving frame and a receiving container. The receiving frame includes a bottom part and a plurality of side parts extending from a peripheral portion of the bottom part creating a receiving space. The receiving container includes a bottom plate and a plurality of sidewalls. The bottom plate is disposed on the bottom part. Each of the sidewalls includes a first side plate extending from an edge portion of the bottom plate and coupled to a corresponding side part to face an outer surface of each of the side parts, and a second side plate bent at an upper end of the first side plate to face an outer surface of the first side plate. Thus, the strength of a display device against an external force, such as a bending stress or a twisting stress, may be improved.

This application claims priority to Korean Patent Application No. 2006-129961, filed on Dec. 19, 2006, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which in its entirety are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a receiving module, a display device including the receiving module, and a method thereof. More particularly, the present invention relates to a receiving module capable of improving strength against an external force, such as a bending stress, a display device having the receiving module, and a method thereof.

2. Description of the Related Art

Generally, a liquid crystal display (“LCD”) device includes a backlight assembly providing light to a display panel, so as to display an image at a place where light is insufficient. A small-sized mobile LCD device, such as a cellular phone or a personal digital assistant (“PDA”), typically includes a light-emitting diode (“LED”) serving as a backlight assembly, which has advantageous characteristics such as small size, low power consumption, light weight, etc.

As a mobile device, such as a cellular phone, becomes slim, a thickness of an LCD panel becomes thinner, for example, from about 0.5 mm or about 0.4 mm to about 0.3 mm. Thus, the strength of a receiving module receiving an LCD panel, an optical unit, etc. is an important factor in evaluating the quality of an LCD device. The receiving module typically includes a mold frame receiving an optical unit and an LCD panel and a bottom chassis receiving the mold frame and including metal to strengthen the LCD device having the receiving module.

As a thickness of a substrate of the LCD panel becomes smaller, the LCD panel becomes weaker to externally applied bending and twisting stresses. Although the strength of the bottom chassis is more important so as to increase the strength of the display device, a thickness of the bottom chassis also becomes thinner.

Korean Laid-Open Patent Publication No. 2003-000305 discloses a display device, in which a bottom chassis having a U-shape is fastened to a rear surface of a mold frame to prevent movement of the bottom chassis even though external impact forces may be applied from any direction. However, the display device merely prevents movement of a bottom chassis, and has limits as to how much strength can be increased against an external force, such as a bending stress or a twisting stress.

Also, Japanese Laid-Open Patent Publication No. 2004-302290 discloses a coupling structure, in which a protrusion formed on a panel holder is inserted into a hole of a housing to firmly fasten the panel holder to the housing. However, the invention merely relates to a coupling structure for firmly coupling the panel holder to the housing, and does not suggest an idea of increasing strength against an external force such as a bending stress or a twisting stress.

BRIEF SUMMARY OF THE INVENTION

The present invention obviates the above problems by providing a module structure capable of increasing strength of a slim display device against an external force. The present invention provides a receiving module for a display device including a sidewall of a predetermined structure to improve strength against an external force such as a bending stress or a twisting stress.

The present invention also provides a display device having the above-mentioned receiving module.

The present invention further provides a method of improving the strength of a receiving module for a display device.

In exemplary embodiments of the present invention, a receiving module for a display device includes a receiving frame and a receiving container. The receiving frame includes a bottom part and a plurality of side parts extending from a peripheral portion of the bottom part to define a receiving space. The receiving container includes a bottom plate and a plurality of sidewalls. The bottom plate is disposed on a rear surface of the bottom part. Each of the sidewalls includes a first side plate extending from an edge portion of the bottom plate and coupled to a corresponding side part to face an outer surface of each of the side parts, and a second side plate bent at an upper end of the first side plate to face an outer surface of the first side plate.

The receiving frame may further include an engaging protrusion formed on at least one of the side parts, and the receiving container may have a first engaging hole formed through a first side plate, where the engaging protrusion is inserted into the first engaging hole. The receiving container may further include a catching protrusion protruding from an inner surface of the first side plate to catch an upper portion of the engaging protrusion. The second side plate may cover the first engaging hole, and extends toward a lower portion of the first side plate. The second side plate may make contact with the first side plate, such as face-to-face contact.

The receiving container may have a second engaging hole formed through the second side plate. The engaging protrusion inserts into the second engaging hole. The second engaging hole may be smaller than the first engaging hole. Alternatively, the receiving container may have an engaging groove formed on the side part, and the receiving container may further include an engaging protrusion formed at the first side plate to be inserted into the engaging groove. In other exemplary embodiments of the present invention, a display device includes a receiving frame, a receiving container, an optical unit, a point light source and a display panel. The receiving frame includes a bottom part including an opening at a central portion and a plurality of side parts extending from a peripheral portion of the bottom part to define a receiving space. The receiving container includes a bottom plate and a plurality of sidewalls. The bottom plate is disposed on a rear surface of the bottom part. Each of the sidewalls includes a first side plate extending from an edge portion of the bottom plate and coupled to the side part to face an outer surface of each of the side parts, and a second side plate bent at an upper end of the first side plate to face an outer surface of the first side plate. The optical unit is disposed on the bottom part. The point light source is disposed adjacent to an inner surface of at least one of the side parts of the receiving frame to face a side surface of the optical unit. The display panel is disposed on the optical unit and supported by a stepped portion formed at the side parts of the receiving frame.

The receiving frame may further include an engaging protrusion formed on an outer surface of at least one of the side parts, and the receiving container may have an engaging hole formed through a first side plate. The engaging protrusion is inserted into the engaging hole. The second side plate of the at least one of the sidewalls may cover and make contact with the engaging hole, and extends toward a lower portion of the first side plate. In still other exemplary embodiments of the present invention, a method for improving strength of a receiving module within a display device includes defining a receiving space in a receiving frame, the receiving frame including a bottom part and a side part extending from a peripheral portion of the bottom part, disposing a bottom plate of a receiving container on a rear surface of the bottom part, extending a first side plate of a sidewall of the receiving container from an edge portion of the bottom plate, coupling the first side plate to the side part to face an outer surface of the side part, and bending a second side plate at an upper end of the first side plate to face an outer surface of the first side plate.

The method may further include forming an engaging protrusion on the side part of the receiving frame, forming a first engaging hole through the first side plate of the receiving container, and inserting the engaging protrusion into the first engaging hole. The method may further include extending a catching protrusion from an inner surface of the first side plate to catch an upper portion of the engaging protrusion. Bending a second side plate at an upper end of the first side plate may include abutting the second side plate to the first side plate in face-to-face contact.

According to the above, a receiving container has a sidewall having a predetermined structure, and thus may have improved strength against an external force, such as a bending stress or a twisting stress, thereby the strength of a display device having the receiving container may be improved.

DETAILED DESCRIPTION OF THE INVENTION

Receiving Module for a Display Device

FIG. 1is a perspective view illustrating an exemplary embodiment of a receiving module for an exemplary display device according to the present invention.FIG. 2is an exploded perspective view illustrating the exemplary receiving module inFIG. 1.

Referring toFIGS. 1 and 2, a receiving module100for a display device receives parts of a display device such as an optical unit, a display panel, etc., as will be described below with respect toFIG. 9. The receiving module100may be employed in a mobile product having a small size such as a cellular phone.

The receiving module100includes a receiving frame10and a receiving container20.

The receiving frame10includes a bottom part5and a plurality of side parts11,13,15and17.

The bottom part5may have a substantially rectangular plate shape. In this exemplary embodiment, the bottom part5includes two long sides facing each other and two short sides facing each other. The bottom part5has an opening9.

In this exemplary embodiment, the receiving frame10includes four side parts11,13,15and17extending from the four sides of the bottom part5to define a receiving space. The four side parts11,13,15and17are defined as a first side part11, a second side part13, a third side part15and a fourth side part17. The first side part11and the second side part13extend from the short sides of the bottom part5and face each other. The third side part15and the fourth side part17extend from the long sides of the bottom part5, and face each other. The third side part15and the fourth side part17are connected to the first side part11and the second side part13.

The receiving frame10may include plastic. A stepped portion7, seeFIG. 3, having two steps is formed on an upper portion of the first side part11, the second side part13, the third side part15and the fourth side part17. The engaging protrusions12and16are formed on an outer surface of the first side part11, the second side part13, the third side part15and the fourth side part17. Each of the engaging protrusions12and16may be gradually thinner from an upper portion to a lower portion, and thus inclined to the outer surface.

The receiving container20may include a metal chassis. The receiving container20includes the receiving frame10, that is, the receiving frame10is received within the receiving container20. The receiving container20may include a bottom plate21, a first sidewall30, a second sidewall40, a third sidewall50and a fourth sidewall60.

The bottom plate21is disposed on a rear surface of the bottom part5of the receiving frame10. The bottom plate21covers the opening9formed through the bottom part5.

The first sidewall30, the second sidewall40, the third sidewall50and the fourth sidewall60extend from four edges of the bottom plate21. The first sidewall30, the second sidewall40, the third sidewall50and the fourth sidewall60face the outer surface of the first side part11, the second side part13, the third side part15and the fourth side part17, respectively.

The first sidewall30, the second sidewall40, the third sidewall50and the fourth sidewall60include a hemming structure. The hemming structure represents a structure in which a predetermined portion of a member is bent, and thus at least two portions of the member are overlapped and may further contact each other. When a member has a hemming structure, the member has great strength against an external force such as a bending stress or a twisting stress.

Referring toFIGS. 1,2and3, the first sidewall30, the second sidewall40, the third sidewall50and the fourth sidewall60include two facing side plates forming the hemming structure. InFIGS. 1 to 3, the first sidewall30includes a first side plate31and a second side plate35, and the third sidewall50includes a first side plate51and a second side plate55. In this exemplary embodiment, since the first sidewall30, the second sidewall40, the third sidewall50and the fourth sidewall60have substantially the same function and structure, only the first sidewall30will be described in detail.

The first side plate31of the first sidewall30extends from an edge of the bottom plate21to face the outer surface of the first side part11. The first side plate31may extend to an upper end portion of the first side part11. An engaging hole32is formed through the first side plate31. An engaging protrusion12formed on the first side part11is inserted into the engaging hole32. Other engaging holes42and62are shown on second sidewall40and fourth sidewall60.

A catching protrusion33is formed on the first side plate31, and over the engaging hole32of the first side plate31. The catching protrusion33is formed adjacent to an upper portion of the engaging protrusion12. When the receiving frame10is downwardly received in the receiving container20, the engaging protrusion12is inserted into the engaging hole32. The catching protrusion33is guided by the outer surface of the first side part11to catch the upper portion of the engaging protrusion12. Other catching protrusions43and63are shown on second sidewall40and fourth sidewall60, relative to the engaging holes42and62, respectively.

The second side plate35faces an outer surface of the first side plate31. The second side plate35is bent at an upper end of the first side plate31, furthest away from the bottom plate21, and extends toward a lower end of the first side plate31along the outer surface of the first side plate31. Thus, the second side plate35covers the engaging hole32formed through the first side plate31. The second side plate35may make contact with the first side plate31. In one exemplary embodiment, the second side plate35entirely makes contact with the outer surface of the first side plate31, such that the second side plate35is in face-to-face contact with the first side plate31. In one exemplary embodiment, the second sidewall40, the third sidewall50and the fourth sidewall60of the receiving container20may have a hemming structure, similar to the overlapped first and second side plates31and35of the first sidewall30.

The receiving container20having the hemming structure may have greater strength against an external force such as a bending stress or a twisting stress than a receiving container having a typical plate-shaped sidewall facing a side part by more than about 1.5 times.

Thus, a display panel or other parts of a display device may be prevented from damage due to an impact, such as a bending stress or a twisting stress that may be incurred when a display device is dropped or otherwise mishandled.

If the second side plate35is bent at the upper end of the first side plate31and is interposed between the first side plate31and the first side part11, then the second side plate35may be difficult to extend to a portion under the engaging hole32of the first side plate31. Thus, in such a case, the second side plate35would extend from the upper end of the first side plate31to the engaging hole32, and an increase in strength of the receiving container20would be restricted.

In contrast, in the exemplary embodiment of the present invention, when the second side plate35is bent to face the outer surface of the first side plate31, the second side plate35may extend to the lower end of the first side plate31, to thereby greatly increase the strength of the receiving container20.

Although the second side plate35covers the engaging hole32, the engaging protrusion12formed on the first side part11may be inserted into the engaging hole32without difficulty. For example, a depth of the engaging protrusion12may be substantially the same as a thickness of the first side plate31. Thus, the receiving frame10may be firmly coupled to the receiving container20, thereby preventing the receiving frame10from being separated from the receiving container20due to an external impact.

FIG. 4is a perspective view illustrating another exemplary embodiment of a receiving module for an exemplary display device according to the present invention.FIG. 5is an exploded perspective view illustrating the receiving module inFIG. 4.FIG. 6is a cross-sectional view taken along line II-II′ inFIG. 5.

Referring toFIGS. 4,5and6, a receiving module300for a display device includes a receiving frame310and a receiving container320.

The receiving frame310includes a bottom part305, a first side part311, a second side part313, a third side part315and a fourth side part317. A stepped portion307, seeFIG. 6, having two steps is formed on an upper portion of the first side part311, the second side part313, the third side part315and the fourth side part317. The bottom part305includes an opening309. The receiving frame310may be substantially the same as the receiving frame10illustrated inFIGS. 1,2and3except for a shape of the first side part311, the second side part313, the third side part315and the fourth side part317.

In this exemplary embodiment, a first guide groove301, a second guide groove (not shown), a third guide groove303and a fourth guide groove (not shown) are formed on an outer surface of the first side part311, the second side part313, the third side part315and the fourth side part317, respectively. A guide groove is formed on each of the side parts, thereby reducing a total size of the receiving module300, which includes a thickness of a wall.

A first guide groove301may be formed on the first side part311so as to be open to a side portion and a lower portion of the first side part311. The second guide groove may be formed similar to the first guide groove301. The third guide groove303may be formed to have a length smaller than that of the third side part315and open to a lower portion of the third side part315. The fourth guide groove may be formed similar to the third guide groove303.

Engaging protrusions312and316are formed on a base surface of the first guide groove301and the third guide groove303, respectively. Although not shown inFIGS. 4 to 6, engaging protrusions are also formed on a base surface of the second and fourth guide grooves.

The receiving container320includes a bottom plate321, a first sidewall330, a second sidewall340, a third sidewall350and a fourth sidewall360. The receiving container320may be substantially the same as the receiving container20illustrated inFIGS. 1,2and3except that the first sidewall330, the second sidewall340, the third sidewall350and the fourth sidewall360are spaced apart from each other at respective corners of the receiving container320. The first sidewall330includes a first side plate331and a second side plate335, the third sidewall350includes a first side plate351and a second side plate355, the second sidewall340includes a first side plate341and a second side plate345, and the fourth sidewall360includes a first side plate361and a second side plate365.

The first sidewall330, the second sidewall340, the third sidewall350and the fourth sidewall360are disposed at the first guide groove301, the second guide groove, the third guide groove303and the fourth guide groove, respectively. Second side plates may not protrude from the side parts so as to reduce a size of the receiving module300. In one exemplary embodiment, second side plates335and355may not protrude from the first and third side parts311and315, respectively. In other words, a width of a wall of the receiving module300including the first side part311and the first sidewall330is reduced because of the first guide groove301. In such an embodiment, an outer surface of the second side plate355may be flush with an outer surface of an upper end portion of the first side part311. An engaging hole332is formed through sidewall330and comparable engaging holes362and342are formed through sidewalls340and360, respectively. This embodiment further includes a catching protrusion333on first side plate331. Comparable catching protrusions343,363are shown on second sidewall340and fourth sidewall360, respectively.

In order to reduce the size of the receiving module300, various changes and modifications may be made by one of ordinary skill in the art, such as in a shape of the guide grooves at the side parts311,313,315,317of the receiving frame310and a spacing interval at a corner between the sidewalls330,340,350,360of the receiving container320.

FIG. 7is a cross-sectional view illustrating still another exemplary embodiment of a receiving module for an exemplary display device according to the present invention.

Referring toFIG. 7, a receiving module500for a display device includes a receiving frame and a receiving container.

The receiving frame includes a bottom part505, a first side part511, a second side part, a third side part and a fourth side part. The receiving frame may be substantially the same as the receiving frame10illustrated inFIG. 2except that an engaging protrusion512formed at each of the side parts includes a longer length than the engaging protrusion12of the receiving frame10inFIG. 2. A stepped portion507having two steps is formed on an upper portion of the first side part511and on the second side part, the third side part and the fourth side part, not shown.

The receiving container includes a bottom plate521, a first sidewall530, a second sidewall, a third sidewall and a fourth sidewall. A first engaging hole is formed through a first side plate of each sidewall of the receiving container. For convenience of description, the first engaging hole532formed in the first side plate531of first sidewall530will be described, and the remaining sidewalls may include similar structures. The engaging protrusion512is inserted into the first engaging hole532. The receiving container may be substantially the same as the receiving container20illustrated inFIG. 2except that a second engaging hole534is formed through the second side plate535of the first sidewall530, and corresponding to the first engaging hole532.

The engaging protrusion512formed on the first side part511is inserted into the first engaging hole532and the second engaging hole534. The engaging protrusion512may have a length substantially equal to combined widths of the first and second side plates531,535. An outer surface of the engaging protrusion512may be substantially flush with an outer surface of the second side plate535. A catching protrusion533is formed on the first side plate531, and catches an upper portion of the engaging protrusion512. Thus, the receiving frame and the receiving container of the receiving module500may be firmly coupled to each other in comparison with the receiving module100illustrated inFIGS. 1 to 3.

The second side plate535is bent at an upper end of the first side plate531and extends toward a lower end of the first side plate531. Thus, the first sidewall530has a sufficiently wide width due to the first and second side plates531,535to prevent the second engaging hole534from deteriorating the strength of the receiving module500. Also, the second side plate535may have a wider width, such that the second engaging hole534may not be an obstacle to increase the strength of the receiving module500.

FIG. 8is a cross-sectional view illustrating still another exemplary embodiment of a receiving module for an exemplary display device according to the present invention.

Referring toFIG. 8, a receiving module600for a display device includes a receiving frame and a receiving container.

The receiving frame includes a bottom part605, a first side part611, a second side part, a third side part and a fourth side part. The receiving frame may be substantially the same as the receiving frame10illustrated inFIG. 2except that an engaging protrusion is removed and an engaging groove612is formed on each side part. A stepped portion607, seeFIG. 3, having two steps is formed on an upper portion of the first side part611, the second side part, the third side part and the fourth side part.

The receiving container includes a bottom plate621, a first sidewall630, a second sidewall, a third sidewall and a fourth sidewall. The receiving container may be substantially the same as the receiving container20illustrated inFIG. 2except that an engaging hole is removed and an engaging protrusion633is formed at the first side plate631of each sidewall. A portion of the first side plate631is cut and bent toward the first side part611to form the engaging protrusion633. A second side plate635of each sidewall of the receiving container is bent at an upper end of a first side plate631to make contact with an outer surface of the first side plate631. The second side plate635extends toward a lower end of the first side plate631.

When the receiving frame is downwardly received in the receiving container, the engaging protrusion633formed at the first side plate631of each sidewall of the receiving container is transformed, such as by being bent back towards the remainder of the first side plate631. The engaging protrusion633is returned to an original shape and inserted into the engaging groove612of the side part611, such that the receiving frame is firmly coupled to the receiving container.

As described inFIGS. 2,5,7and8, the receiving container has a predetermined hemming structure. Particularly, the first side plate of each sidewall of the receiving container is connected to the edge of the bottom plate, the second side plate of each sidewall of the receiving container is bent at the upper end of the first side plate and covers the outer surface of the first side plate.

Alternatively, the receiving container may have a hemming structure different from the above-described structure. Particularly, the second side plate may be connected to an edge of the bottom plate, and the first side plate may be bent at an upper end of the second side plate and cover an inner surface of the second side plate. Also, the engaging hole and the catching protrusion may be formed at the first side plate.

Display Device

FIG. 9is a cross-sectional view illustrating an exemplary embodiment of a display device according to the present invention.

Referring toFIG. 9, a display device700includes a receiving frame, a receiving container, an optical unit770, a point light source780and a display panel790.

The receiving frame and the receiving container may be substantially the same as the receiving frame10and the receiving container20illustrated inFIGS. 1,2and3. Alternatively, the receiving frame and the receiving container may be replaced with the receiving frames310,510and610and the receiving containers320,520and620illustrated inFIGS. 5,7and8, respectively.

The optical unit770is disposed on the bottom part705of the receiving frame. The optical unit770may include a light-guiding plate771, a light-diffusing sheet773and light-condensing sheets775and777. The light-guiding plate771is spaced apart from an inner surface of the first side part711of the receiving frame by a predetermined distance. The light-diffusing sheet773and the light-condensing sheets775and777are successively disposed on the light-guiding plate771. The optical unit770may further include a light-reflecting sheet779. The light-reflecting sheet779is disposed between the bottom part705and the light-guiding plate771to cover an opening formed through the bottom part705and to reflect light exiting a bottom surface of the light guiding plate771back towards the display panel790.

The point light source780is disposed between the first side part711and a side surface of the light-guiding plate771, and may be disposed on the light-reflecting sheet779. The display device700may include a plurality of point light sources780. The point light source780may include a white light-emitting diode (“LED”) emitting a white light. Alternatively, the point light source780may include a red light-emitting chip emitting red light, a green light-emitting chip emitting green light, and a blue light-emitting chip emitting blue light.

The display device700may further include a power printed circuit film785having flexibility. A portion of the power printed circuit film785may overlap an upper edge portion of the light-guiding plate771. The point light source780is mounted on the power printed circuit film785. A groove (not shown) may be formed on the first side part711. The power printed circuit film785may be drawn out through the groove.

The display panel790is disposed on the optical unit770. The display panel790may be supported by a stepped portion707formed at an upper portion of the first side part711, the second side part, the third side part, and the fourth side part. The display device700may further include an adhesive member797interposed between the stepped portion707and the display panel790. The display panel790may include a lower substrate791, an upper substrate795and a liquid crystal layer (not shown).

The lower substrate791may include a plurality of pixels. The upper substrate795is disposed on a portion of the lower substrate791except for an edge portion of the lower substrate791adjacent to the first side part711. The upper substrate795may include a color filter layer facing the pixels. The liquid crystal layer is interposed between the lower substrate791and the upper substrate795.

The display panel790may further include a driver chip793. The driver chip793is mounted on the lower substrate791corresponding to the point light sources780. A panel printed circuit film may be connected to an edge of the lower substrate791having the driver chip793, such that the driver chip793may be electrically connected to the panel printed circuit film. The driver chip793drives the display panel790in response to a panel driving signal externally applied to the panel printed circuit film. The power printed circuit film785having the point light source780may be drawn out of the receiving frame to be electrically connected to the panel printed circuit film.

In a mobile display device700such as a cellular phone, a thickness of the display panel790, in one exemplary embodiment, a thickness of the lower substrate791and the upper substrate795is only a few millimeters. Thus, the display panel790is weak against an external force such as a bending stress or a twisting stress.

A second side plate735of each sidewall of the receiving container is bent at an upper end of a first side plate731to make contact with an outer surface of the first side plate731. The second side plate735extends toward a lower end of the first side plate731. The first side plate731extends from the bottom plate721. Thus, each sidewall of the receiving container has a double-walled structure, and the sidewall730shows an exemplary embodiment of such a structure. As a result, the receiving container may have great strength against a bending stress or a twisting stress. Also, an engaging protrusion712of the receiving frame is firmly coupled to an engaging hole732formed through the first side plate731of each sidewall. Therefore, the display panel790, the optical unit770, etc. may be prevented from damage due to an external force such as a bending stress or a twisting stress.

According to the present invention, a receiving container having metal includes a sidewall having a hemming structure. A second side plate of the sidewall is outwardly bent at an upper end of the first side plate and has a width similar to a first side plate. The receiving frame may be firmly coupled to the receiving container by coupling an engaging protrusion and an engaging hole or groove. Thus, the strength of a receiving module for a display device may be improved, and the display device may have an increased resistivity to an external force.

According to the present invention, a method for improving strength of a receiving module within a display device includes defining a receiving space in a receiving frame, the receiving frame including a bottom part and a side part extending from a peripheral portion of the bottom part, disposing a bottom plate of a receiving container on a rear surface of the bottom part, extending a first side plate of a sidewall of the receiving container from an edge portion of the bottom plate, coupling the first side plate to the side part to face an outer surface of the side part, and bending a second side plate at an upper end of the first side plate to face an outer surface of the first side plate.

The method may further include forming an engaging protrusion on the side part of the receiving frame, forming a first engaging hole through the first side plate of the receiving container, and inserting the engaging protrusion into the first engaging hole. The method may further include extending a catching protrusion from an inner surface of the first side plate to catch an upper portion of the engaging protrusion. Bending a second side plate at an upper end of the first side plate may include abutting the second side plate to the first side plate in face-to-face contact. Although exemplary embodiments of the present invention have been described, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art within the spirit and scope of the present invention as hereinafter claimed.