# Patent

## Title
Back frame of flat panel display device, backlight system, and flat liquid crystal display device

## Abstract

The present invention provides a back frame of flat panel display device, which includes at least first and second primary assembling pieces. The at least two primary assembling pieces are joined to form the back frame. The primary assembling pieces have a snap-on engagement section, and the snap-on engagement section mates a front frame of the flat panel display device. The present invention provides a back frame of front panel display device, a backlight system, and a flat liquid crystal display device that form a snap-on engagement section on a primary assembling piece to mate a snap-on engagement of a front frame of the flat panel display device to fix the front frame of the flat panel display device and also to allow of easy disassembling of the flat panel display device.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of displaying techniques, and in particular to a back frame of a flat panel display device, a backlight system, and a flat liquid crystal display device.
2. The Related Arts
The state-of-the-art liquid crystal display device comprises a front bezel, a panel, and a backlight module, of which the backlight module comprises a back frame, a reflector plate, a light guide, and a lighting assembly.
Currently, a variety of display panels of different sizes are available in the market to meet different needs of general consumers. For example, in the field of television set, the sizes of liquid crystal panels include 31.5, 42, 46, 48, and 55 inches. Different back frame molds are provided for liquid crystal planes of different sizes.
Referring to FIG. 1, FIG. 1 is a schematic view showing a conventional back frame of liquid crystal display device. As shown in FIG. 1, the conventional back frame 10 is a unitary back frame, and it is often that a unitary back frame 10 is made with metal stamping or plastic injection molding. The unitary back frame 10 consumes much material and has a high material cost. Further, a large-sized back frame 10 requires large-sized stamping equipment, and the size of mold corresponding to such a back frame 10 is large and the structure complicated, making the expenditure of the back frame mold high. As a consequence, the conventional back frame is of a high cost.
In the known techniques, a front frame of a flat panel display device is fixed on a back frame by means of for example rivet. This makes the assembling and disassembling of a frame structure of the flat panel display device.
SUMMARY OF THE INVENTION
The technical issue to be addressed by the present invention is to provide a back frame of flat panel display device, a backlight system, and a flat liquid crystal display device, which facilitate assembling and disassembling of a frame structure of the flat panel display device.
To address the above technical issue, the present invention adopts a technical solution that is:
a back frame of flat panel display device, the back frame comprising at least first and second primary assembling pieces, the at least two primary assembling pieces being joined to form the back frame, the primary assembling pieces having a snap-on engagement section, the snap-on engagement section mateable with a front frame of the flat panel display device.
Wherein, the first primary assembling piece has an end forming at least two joint sections, each of the joint sections having a structure mating an end of the second primary assembling piece, the first primary assembling piece using one of the joint sections to join the corresponding end of the second primary assembling piece.
Wherein, the at least two joint sections are arranged to space from each other in a lengthwise direction of the first primary assembling piece.
Wherein, the joint sections comprise recesses formed in a surface of the first primary assembling piece and having a shape corresponding to the end of the second primary assembling piece for receiving the end of the second primary assembling piece.
Wherein, the joint sections comprise recesses formed in a surface of the first primary assembling piece, the second primary assembling piece having a surface forming protrusions at corresponding positions, the protrusions being receivable in the recesses to join the first primary assembling piece and the second primary assembling piece to each other.
Wherein, the back frame comprises a third primary assembling piece and a fourth primary assembling piece; and the first primary assembling piece, the second primary assembling piece, the third primary assembling piece, and the fourth primary assembling piece are joined to each other to form the back frame.
To address the above technical issue, the present invention adopts a technical solution that provides a backlight system, which comprises a light source, a light homogenization mechanism, and a back frame as described in any of the above embodiments; and the back frame carries the light source and the light homogenization mechanism.
To address the above technical issue, the present invention adopts a technical solution that provides a flat liquid crystal display device. The flat liquid crystal display device comprises a liquid crystal panel, a front frame, a back panel, and a backlight system as described above.
Wherein, the front frame forms a front-frame snap-on engagement section at a location corresponding to a hooking slot of the assembling pieces, the front-frame snap-on engagement section being engageable with the snap-on engagement section of the primary assembling pieces to fix the liquid crystal panel and the backlight system.
Wherein, the front-frame snap-on engagement section comprises a hooking slot or a hook.
The efficacy of the present invention is that to be distinguished from the state of the art, the present invention provides a back frame of flat panel display device, a backlight system, and a flat liquid crystal display device that form a snap-on engagement section on a back frame for mating a snap-on engagement section of a front frame so that through deforming the hook of the front frame, the front frame can be easily assembled to or disassembled from the back frame, thereby facilitating the assembling and disassembling of the frame structure of the flat panel display device.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view showing a conventional back frame of liquid crystal display device;
FIG. 2 is a schematic view showing a first embodiment of a flat panel display device according to the present invention;
FIG. 3 is a schematic view showing a first embodiment of a back frame of flat panel display device according to the present invention;
FIG. 4 is a schematic view showing a second embodiment of a back frame of flat panel display device according to the present invention;
FIG. 5 is a schematic view showing a third embodiment of a back frame of flat panel display device according to the present invention;
FIG. 6 is a schematic view showing a joining arrangement of a first embodiment of a flat panel display device according to the present invention;
FIG. 7 is a schematic view showing a diagonally-arranged first secondary assembling piece mounted to a main frame structure of a second embodiment of a flat panel display device according to the present invention;
FIG. 8 is a schematic view showing a first secondary assembling piece and a second secondary assembling piece mounted to a main frame structure of a third embodiment of a flat panel display device according to the present invention;
FIG. 9 is a schematic view showing a first embodiment of joint sections of a back frame of flat panel display device according to the present invention;
FIG. 10 is a cross-sectional view showing the first embodiment of the joint section of FIG. 9;
FIG. 11 is a schematic view showing a second embodiment of a joining arrangement of a joint section of a back frame of a flat panel display device according to the present invention;
FIG. 12 is a schematic view showing a third embodiment of a joining arrangement of a joint section of a back frame of a flat panel display device according to the present invention;
FIG. 13 is a schematic view showing a fourth embodiment of a joining arrangement of a joint section of a back frame of a flat panel display device according to the present invention;
FIG. 14 is a schematic view showing a second embodiment of joint sections of a back frame of flat panel display device according to the present invention;
FIG. 15 is a schematic view showing a third embodiment of joint sections of a back frame of flat panel display device according to the present invention;
FIG. 16 is a flow chart showing a preferred embodiment of a method for manufacturing a back frame of a flat panel display device according to the present invention;
FIG. 17 is a schematic view showing a preferred embodiment of a flat panel display device with a touch screen according to the present invention;
FIG. 18 is a schematic view showing a preferred embodiment of a stereoscopic display device according to the present invention;
FIG. 19 is a schematic view showing a preferred embodiment of a plasma display device according to the present invention;
FIG. 20 is a schematic view showing mating and snap-on engagement between a back frame and a front frame according to the present invention; and
FIG. 21 is another schematic view showing mating and snap-on engagement between a back frame and a front frame according to the present invention.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 2-3, FIG. 2 is a schematic view showing a flat panel display device according to a first embodiment of the present invention and FIG. 3 is a schematic view showing a first embodiment of a back frame of flat panel display device according to the present invention. As shown in FIG. 2, the flat panel display device 20 according to the instant embodiment comprises: a backlight system 21 and a display panel 22. The backlight system 21 is arranged on a back side of the display panel 22 and supplies light to the display panel 22.
In the instant embodiment, the backlight system 21 comprises a light source 25, a light homogenization mechanism 24, and a back frame 23. The back frame 23 carries the light source 25 and the light homogenization mechanism 24. When the backlight system 21 is an edge lighting type, the light homogenization mechanism 24 is a light guide; and when the backlight system 21 is a direct type, the light homogenization mechanism 24 is a diffuser plate. The back frame 23 comprises at least a first primary assembling piece and a second primary assembling piece, and the two of at least a first and second primary assembling pieces constitute a main frame structure 27 of the back frame 23.
Referring also to FIG. 3, the back frame 23 of the first embodiment comprises a first primary assembling piece 261 and a second primary assembling piece 262. The first primary assembling piece 261 has an end joined to an end of the second primary assembling piece 262, and the first primary assembling piece 261 has another end joined to another end of the second primary assembling piece 262 in order to form the main frame structure 27 of the back frame 23. The first primary assembling piece 261 and the second primary assembling piece 262 are both aluminum pieces or galvanized steel pieces. In the instant embodiment, the first primary assembling piece 261 and the second primary assembling piece 262 are L-shaped.
Referring also to FIG. 4, the back frame 23 of a second embodiment comprises a first primary assembling piece 281, a second primary assembling piece 282, and a third primary assembling piece 283. The three primary assembling pieces 281, 282, and 283 are assembled and joined to form a main frame structure 27 of the back frame 23. The three primary assembling pieces 281, 282, and 283 are all aluminum pieces or galvanized steel pieces. In the instant embodiment, the first primary assembling piece 281 is L-shaped, and the second and third primary assembling pieces 282, 283 are straight linear.
Further, the back frame 23 further comprises secondary assembling pieces arranged inside and joined to the main frame structure 27.
A detailed description will be given to the back frame 23 of the flat panel display device 20 according to the present invention, which comprises four primary assembling pieces and two secondary assembling pieces.
Referring to FIG. 5, FIG. 5 is a schematic view showing a third embodiment of a back frame of flat panel display device according to the present invention. As shown in FIG. 5, in the instant embodiment, a back frame 23 comprises: a first primary assembling piece 231, a second primary assembling piece 232, a third primary assembling piece 233, a fourth primary assembling piece 234, a first secondary assembling piece 235, a second secondary assembling piece 236, and bracing pieces 2371, 2372, 2373, 2374, 2375, 2376, and 2377. The first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, and the fourth primary assembling piece 234 are joined to each other in a leading end-to-tailing end manner to constitute a main frame structure 27 of the back frame 23. The first secondary assembling piece 235 and the second secondary assembling piece 236, serving as ancillary assembling pieces, are arranged in the main frame structure 27 and joined to the main frame structure 27.
Specifically, an end of the first primary assembling piece 231 is joined to an end of the second primary assembling piece 232, another end of the second primary assembling piece 232 is joined to an end of the third primary assembling piece 233, another end of the third primary assembling piece 233 is joined to an end of the fourth primary assembling piece 234, and another end of the fourth primary assembling piece 234 is joined to another end of the first primary assembling piece 231 in order to form the rectangular main frame structure 27. The first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, and the fourth primary assembling piece 234 are all aluminum pieces or galvanized steel pieces. In the instant embodiment, the first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, and the fourth primary assembling piece 234 are straight linear, yet in other embodiments, it is apparent to those skilled in the art to make all the first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, and the fourth primary assembling piece 234 L-shaped, or some being straight linear and the remaining being L-shaped. For example, in FIG. 3, the first primary assembling piece 261 and the second primary assembling piece 262 are both L-shaped; in FIG. 4, the first primary assembling piece 281 is L-shaped, while the second and third primary assembling pieces 282 and 283 are straight linear.
In the instant embodiment, the back frame 23 of the flat panel display device 20 is formed by joining connection. As shown in FIG. 6, an illustrative example is given for the connection of an end of the first primary assembling piece 231 to an end of the second primary assembling piece 232, wherein the end of the second primary assembling piece 232 is joined to the end of the first primary assembling piece 231 by means of for example screwing, fastening, or welding, to have the end of the second primary assembling piece 232 connected to the end of the first primary assembling piece 231.
In the instant embodiment, the first secondary assembling piece 235 and the second secondary assembling piece 236 are arranged in the main frame structure 27 of the back frame 23. An end of the first secondary assembling piece 235 is joined to the first primary assembling piece 231 and another end of the first secondary assembling piece 235 is joined to the third primary assembling piece 233; and an end of the second secondary assembling piece 236 is joined to the first primary assembling piece 231 and another end of the second secondary assembling piece 236 is joined to the third primary assembling piece 233. Further, the second primary assembling piece 232, the fourth primary assembling piece 234, the first secondary assembling piece 235, and the second secondary assembling piece 236 are arranged parallel to each other. In other embodiments, those skilled in the art may arrange at least one secondary assembling piece in the main frame structure 27. For example, only the first secondary assembling piece 235 is arranged in the main frame structure 27. Further, the two ends of the first secondary assembling piece 235 can be selectively joined to at least two of the primary assembling pieces of the first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, and the fourth primary assembling piece 234. For example, the first secondary assembling piece 235 is set diagonally in the main frame structure 27, as shown in FIG. 7. Similarly, the two ends of the second secondary assembling piece 236 can be selectively joined to at least two of the primary assembling pieces of the first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, and the fourth primary assembling piece 234. For example, the two ends of the first secondary assembling piece 235 are respectively joined to the first primary assembling piece 231 and the second primary assembling piece 232 that are adjacent to each other and the two ends of the second secondary assembling piece 236 are respectively joined the third primary assembling piece 233 and the fourth primary assembling piece 234 that are adjacent to each other, as shown in FIG. 8.
In the instant embodiment, the back frame 23 comprises seven bracing pieces 2371, 2372, 2373, 2374, 2375, 2376, and 2377. The bracing piece 2371 is fixed to the fourth primary assembling piece 234; the bracing pieces 2372, 2373 are both fixed to the first secondary assembling piece 235; the bracing piece 2374 is fixed to the second secondary assembling piece 236; the bracing piece 2375 is fixed to the second primary assembling piece 232; and the bracing pieces 2376, 2377 are each fixed, at two ends thereof, to the first secondary assembling piece 235 and the second secondary assembling piece 236. In practice, the bracing pieces can be fixed to one or more of the first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, the fourth primary assembling piece 234, the first secondary assembling piece 235, and the second secondary assembling piece 236. In other embodiments, those skilled in the art may mount bracing pieces of any other numbers to the back frame 23, such as one or more bracing pieces. Further, the bracing pieces can be releasably fixed to one or more of the first primary assembling piece 231, the second primary assembling piece 232, the third primary assembling piece 233, the fourth primary assembling piece 234, the first secondary assembling piece 235, and the second secondary assembling piece 236.
The bracing pieces 2371, 2372, 2373, 2374, 2375, 2376, and 2377 may be provided with bumps (not labeled) so that the back frame 23 may fix components, such as circuit boards, with such bumps.
Molds for making the back frame 23 will be described. In the instant embodiment, the first primary assembling piece 231 and the third primary assembling piece 233 are of the same size and shape so that they can be made by stamping with the same mold. The second primary assembling piece 232, the fourth primary assembling piece 234, the first secondary assembling piece 235, and the second secondary assembling piece 236 are of the same size and shape so that they can be made by stamping with the same mold, making it possible to share the mold. Thus, the back frame 23 of the present invention can be made by stamping with only two small-sized molds, and compared to the conventional back frame 10 that requires a large-sized mold, the molds for making the back frame 23 of the present invention are simple in structure and small in size and thus the cost of mold for the back frame 23 can be lowered. Further, compared to the whole back frame structure of the conventional back frame 10, the back frame 23 of the present invention can significantly save material used and thus reduce the manufacturing cost of the flat panel display device 20.
Referring to FIG. 9, FIG. 9 is a schematic view showing a first embodiment of joint sections of a back frame of flat panel display device according to the present invention. As shown in FIG. 9, in the instant embodiment, an end of the first primary assembling piece is provided with two joint sections, and the joint sections have a structure mating an end of the second primary assembling piece so that the first primary assembling piece can be joined to a corresponding end of the second primary assembling piece.
Specifically, the first primary assembling piece 231 has an end forming joint sections 2311, 2312, and the joint sections 2311, 2312 are arranged in a spaced manner in a lengthwise direction of the first primary assembling piece 231. The joint sections 2311, 2312 are formed by forming recesses having a shape mating an end of the second primary assembling piece 232 in the first primary assembling piece 231 in order to receive the end of the second primary assembling piece 232 therein. As shown in FIG. 10, the joint sections 2311, 2312 are recesses that do not extend through opposite surfaces of the end of the first primary assembling piece 231 and the recesses are of a rectangular shape with the second primary assembling piece 232 being straight linear.
To assemble a large-sized back frame 23, the joint section 2311 that is close to the very end of the first primary assembling piece 231 is first taken and a second primary assembling piece 232 having a corresponding width is selected. Afterwards, an end of the second primary assembling piece 232 is positioned in the recess of the joint section 2311. And then, means, such as screwing, fastening, or welding, is applied to join and fix the end of the second primary assembling piece 232 to the joint section 2311. To assemble a small-sized back frame 23, the joint section 2312 that is distant from the very end of the first primary assembling piece 231 is first chosen and a second primary assembling piece 232 having a corresponding width is selected. Afterwards, an end of the second primary assembling piece 232 is positioned in the recess of the joint section 2312. And then, means, such as screwing, fastening, or welding, is applied to join and fix the end of the second primary assembling piece 232 to the joint section 2312. Specifically, for example the second primary assembling piece 232 forms a protrusion at a corresponding location on a surface thereof, and the protrusion of the second primary assembling piece 232 is embedded in the recess the first primary assembling piece 231 at a corresponding location in order to join the first primary assembling piece 231 and the second primary assembling piece 232, as shown in FIG. 11. Furthermore, the recess of the first primary assembling piece 231 can be a recess of a multi-stepped configuration and the second primary assembling piece 232 forms, at a corresponding location, a protrusion having a multi-stepped configuration corresponding to the recess, as shown in FIG. 12. Further, as shown in FIG. 13, taking the joint section 2311 as an example, the recess of the first primary assembling piece 231 forms, in a bottom thereof, a first through hole 2313, and the second primary assembling piece 232 forms, at a location corresponding to the joint section 2311, a second through hole 2321. The back frame 23 further comprises a fastener 240. The fastener 240 extends through the first through hole 2313 and the second through hole 2321 to joint the first primary assembling piece 231 and the second primary assembling piece 232 to each other.
As shown in FIG. 14, in another embodiment of the back frame of flat panel display device according to the present invention, the recesses of the joint sections 2311, 2312 of the first primary assembling piece 231 are of a circular shape. Yet, in other embodiments, those skilled in the art may arrange the shape of the recesses to be other polygonal configurations, such as triangle.
As shown in FIG. 15, in another embodiment of the back frame of flat panel display device according to the present invention, the joint sections 2311, 2312 are recesses that do not extend through opposite surfaces of the first primary assembling piece 231, whereby an end of the second primary assembling piece 232 is movable within the joint sections 2311, 2312. For example, after the end of the second primary assembling piece 232 is set extending beyond and joined and fixed to the joint section 2312, the portion of extension is then trimmed off so that the length of the second primary assembling piece 232 that serves as a primary assembling piece of the back frame can be adjusted.
In a practical application, the other end of the first primary assembling piece 231 and both ends of the third primary assembling piece 233 are all provided with two joint sections having a structure identical to that of the joint sections 2311, 2312. The ends of the second primary assembling piece 232 and the ends of the fourth primary assembling piece 234 may be subjected to specific designs or no design at all according to the application. For example:
(1) In a first situation, as shown in FIG. 10, the two ends of the second primary assembling piece 232 and the two ends of the fourth primary assembling piece 234 are of no specific design. In other words, the ends are of the same structure as the remaining portions. Under this condition, in making a join with a selected joint section 2311 (2312) at one end of the first primary assembling piece 231 (the same applicable to the other end), if an attempt is made to change the width of the back frame 23, then the length of the corresponding second primary assembling piece 232 and fourth primary assembling piece 234 must be selected accordingly. Namely, if the joint section 2311 that is close to the very end of the first primary assembling piece 231 is selected for joining, then no trimming is applied to the second primary assembling piece 232 and the fourth primary assembling piece 234 or the portion that is trimmed off is short; if the joint section 2312 that is distant from the very end of the first primary assembling piece 231 is selected for joining, then the second primary assembling piece 232 and the fourth primary assembling piece 234 are trimmed and the trimmed portion being long or short is according to the distance that the joint section is from the very end of the first primary assembling piece 231 being great or small; and
(2) In a second situation, it is similar to the first situation, but as shown in FIG. 11, the second primary assembling piece 232 and the fourth primary assembling piece 234 use different protrusions to respectively mate the first primary assembling piece 231 and the third primary assembling piece 233 in order to realize change of width of the back frame 23; similarly, if a joint section 2312 other than the first joint section 2311 that is close to the very end of the first primary assembling piece 231 is selected for joining, then before or after joining, excessive portions of the second primary assembling piece 232 and the fourth primary assembling piece 234 may be trimmed off.
This also applicable to a main frame structure 27 of the back frame 23 that is formed by joining two L-shaped primary assembling pieces.
In summary, the present invention provides a back frame 23 having a first primary assembling piece that is provided with at least two joint sections. The number of the joint section can be selected according to the requirement of customers. In the instant embodiment, a description is given to an example comprising two joint sections 2311, 2312. Thus, to prepare the molds for making the back frame 23, only two sets of mold are needed, namely one mold for a first primary assembling piece and the other mold for a second primary assembling piece. The first primary assembling piece may be provided with a plurality of joint sections for joining operation in order to form various sizes for the back frame 23. To assemble the back frame 23, based on the desired size of the back frame 23, the corresponding one of the joint sections is selected. With the joint section, the second primary assembling piece is joined to the joint section of the first primary assembling piece and the other joint section of the first primary assembling piece that is located outward of the joining location of the second primary assembling piece is trimmed off to obtain a desired size of the back frame 23. Compared to the conventional technology that requires different back frame molds for making different sizes of back frame 10, the back frame of the flat panel display device 23 according to the present invention requires only a mold for the first primary assembling piece and a mold for the second primary assembling piece 28 so that mold sharing among various sizes of product can be realized and the molds used are of simple structures, allowing of reduction of expenditure of the molds for back frames.
The present invention also provides a mold for making a back frame of flat panel display device. The back frame mold is provided with a main pattern for forming a primary assembling piece of the back frame and the main pattern comprises a sub-pattern that forms at least two joint sections on an end of the primary assembling piece. The primary assembling piece comprises the previously discussed first primary assembling piece and second primary assembling piece, corresponding to the above mentioned main pattern; and the joint section comprises the previously discussed joint section of the first primary assembling piece, corresponding to the above mentioned sub-pattern. Repeated description is omitted herein.
As shown in FIG. 16, the present invention also provides a method for making a back frame of flat panel display device. The method comprises the following steps:
Step 501: manufacturing at least first and second primary assembling pieces, in which the first primary assembling piece has an end forming at least two joint sections, each of the joint sections having a structure that mates a corresponding end of the second primary assembling piece; and
Step 502: selecting one joint section of the at least two joint sections according to a size of the back frame to join the corresponding end of the second primary assembling piece.
In the instant embodiment, when other joint sections are present between the joining location of the second primary assembling piece and the end of the first primary assembling piece, before or after the step of selecting one joint section of the at least two joint sections according to a size of the back frame to join the corresponding end of the second primary assembling piece, the other joint sections of the first primary assembling piece that are located outward of the joining position of the second primary assembling piece are trimmed off. The first primary assembling piece comprises the previously discussed first primary assembling piece, and the second primary assembling piece comprises the previously discussed second primary assembling piece, and repeated description will be omitted herein.
As shown in FIG. 17, the flat panel display device 20 of the present invention further comprises a touch screen 29. The touch screen 29 is arranged on a light exit surface of the display panel 22 of the flat panel display device 20. The flat panel display device 20 comprises: the backlight system 21 and the above discussed display panel 22. The backlight system 21 is arranged at the back side of the display panel 22 and supplies light to the display panel 22.
The backlight system 21 comprises a light source 25, a light homogenization mechanism 24, and a back frame 23. The back frame 23 carries the light source 25 and the light homogenization mechanism 24. When the backlight system 21 is an edge lighting type, the light homogenization mechanism 24 is a light guide; and when the backlight system 21 is a direct type, the light homogenization mechanism 24 is a diffuser plate. The back frame 23 comprises at least a first primary assembling piece and a second primary assembling piece, and the at least one first and second primary assembling pieces constitute a main frame structure 27 of the back frame 23.
It is noted that the flat panel display device 20 of the present invention can be a liquid crystal display device or a liquid crystal television.
The present invention also provides a stereoscopic display device 30, as shown in FIG. 18. The stereoscopic display device 30 comprises a liquid crystal lens grating 31, a backlight system 32, and a display panel 33. The liquid crystal lens grating 31 is arranged on a light exit surface of the display panel 33. The backlight system 32 can be a backlight system of one of the above discussed embodiments, such as the backlight system 32 comprising the back frame 23. The back frame 23 comprises at least first primary assembling piece and the second primary assembling piece. The at least first and second primary assembling pieces form a main frame structure of the back frame. Repeated description will be omitted herein.
The present invention also provides a plasma display device 40, as shown in FIG. 19. The plasma display device 40 comprises a plasma display panel 41 and a back frame 42. The back frame 42 is arranged at a back side of the display panel 41. The back frame 42 can be the back frame of any of the previous embodiments and repeated description will be omitted herein.
The present invention also provides a back frame 512 that comprises a snap-on engagement section. As shown in FIG. 20, FIG. 20 is a schematic view showing snap-on engagement between the back frame 512 and a front frame 510. The front frame 510 has barbed extensions forming hooks. The back frame forms hooking slots. When the hooks are being inserted into the hooking slots, the hooks are deflected by projecting portions of the hooking sots and when the hooks are completely received in the hooking slots, resiliency of the hooks restores the positions of the hooks. In this way, the hooks and hooking slots are set in complete engagement conditions. The front frame 510 may then tightly engage the back frame. To disassemble, the hooks of the front frame 510 are depressed down to cause deformation thereof and then the front frame 510 can be easily removed from the back frame 512.
The present invention also provides a back frame 512 that comprises a snap-on engagement section. As shown in FIG. 21, FIG. 21 is a schematic view showing snap-on engagement between the back frame 512 and a front frame 510. The principle of snap-on engagement is basically similar to what described above and the only difference here is that the snap-on engagement section of the back frame comprise a hook.
With the above discussed manners, the present invention provides a flat panel display device, a stereoscopic display device, and a plasma display device that form a snap-on engagement section on a back frame to mate a snap-on engagement section of a front frame to secure the entire frame structure of the flat panel display device and also to allow of easy assembling and disassembling of the flat panel display device. Further, the at least two primary assembling pieces are joined to form the back frame so that the back frame has a simple structure, the expenditure for mold of back frame is reduced, and the material used for back frame is saved, and thus the cost is lowered down.
Embodiments of the present invention have been described, but are not intending to impose any undue constraint to the appended claims of the present invention. Any modification of equivalent structure or equivalent process made according to the disclosure and drawings of the present invention, or any application thereof, directly or indirectly, to other related fields of technique, is considered encompassed in the scope of protection defined by the clams of the present invention.

## Claims

1. A back frame of a flat panel display device, wherein the back frame comprises at least first and second primary assembling pieces, the first and second primary assembling pieces being joined to form the back frame, the primary assembling pieces having a snap-on engagement section, the snap-on engagement section mateable with a front frame of the flat panel display device;
wherein the first primary assembling piece has an end connectable to an end of the second primary assembling piece for jointing the first and second primary assembling pieces, the end of the first primary assembling piece forming at least two joint sections, each of the joint sections having a structure mating the end of the second primary assembling piece, the end of the second primary assembling piece being switchably jointed to a first one and a second one of the at least two joint sections of the first primary assembling piece so that the second primary assembling piece is connected to the first primary assembling piece in a position-adjustable manner to respectively define a first size and a second size of the back frame, the second size being different from the first size.

2. The back frame as claimed in claim 1, wherein:
the at least two joint sections are arranged to space from each other in a lengthwise direction of the first primary assembling piece.

3. The back frame as claimed in claim 2, wherein:
the joint sections comprise recesses formed in a surface of the first primary assembling piece and having a shape corresponding to the end of the second primary assembling piece for receiving the end of the second primary assembling piece.

4. The back frame as claimed in claim 2, wherein:
the joint sections comprise recesses formed in a surface of the first primary assembling piece, the second primary assembling piece having a surface forming protrusions at corresponding positions, the protrusions being receivable in the recesses to join the first primary assembling piece and the second primary assembling piece to each other.

5. The back frame as claimed in claim 1, wherein:
the back frame comprises a third primary assembling piece and a fourth primary assembling piece; and
the first primary assembling piece, the second primary assembling piece, the third primary assembling piece, and the fourth primary assembling piece are straight linear and are connected to each other in a leading end-to-tailing end manner to circumferentially form the back frame.

6. A backlight system, wherein:
the backlight system comprises a light source, a light homogenization mechanism, and a back frame; and
the back frame carries the light source and the light homogenization mechanism, the back frame being a back frame as claimed in claim 1.

7. A flat liquid crystal display device, wherein:
the flat liquid crystal display device comprises a liquid crystal panel, a front frame, a back panel, and a backlight system according to claim 6.

8. The flat liquid crystal display device as claimed in claim 7, wherein the front frame forms a front-frame snap-on engagement section at a location corresponding to a hooking slot of one of the first and second assembling pieces, the front-frame snap-on engagement section being engageable with the snap-on engagement section of a corresponding primary assembling piece to fix the liquid crystal panel and the backlight system.

9. The flat liquid crystal display device as claimed in claim 8, wherein the front-frame snap-on engagement section comprises a hooking slot or a hook.