Liquid crystal display device, and method for assembling the same

A method for assembling a liquid crystal display device includes: a) assembling together a front frame, a liquid crystal panel and an optical plate unit in a dust-free environment to form a first unit in a manner that the liquid crystal panel closes an opening in the front frame and that a sealed state is established between the liquid crystal panel and the optical plate unit; b) assembling a circuit board to one side of a rear frame without requirement of a dust-free environment to form a second unit; c) assembling a light source to one of the first and second units; and d) interconnecting the first and second units without requirement of a dust-free environment in a manner that the light source is able to provide light to a light-entrance surface of the optical plate unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device and a method for assembling the same, more particularly to a liquid crystal display device assembled by directly assembling a front frame and optical components together, and a method for assembling the liquid crystal display device.

2. Description of the Related Art

During a process of assembling a liquid crystal display device, if there are unwanted particles between optical components, such as a liquid crystal panel, an optical film, or a diffuser plate, a production yield rate may be affected. Therefore, a liquid crystal module92as shown inFIG. 1is assembled using an iron frame921(called as bezel), a plastic frame923, and a back cover928to tightly combine a liquid crystal panel922, an optical film924, a diffuser plate925, a light source device926, and a reflective sheet927with each other in a dust-free environment at least with a level of Class-10000 (i.e., a number of particles with particle size that is greater than 0.5 μm is less than 10000 per 1 cubic ft.) according to US FED STD 209E to inhibit entry of the particles into the liquid crystal module92. Then, as shown inFIG. 2, the liquid crystal module92is assembled with a front frame91, a circuit board93, a power source unit94, a transformer96, and a rear frame95to form a liquid crystal display device9.

Since the above-mentioned liquid crystal display device9includes various components, an assembly process thereof is complex and time-consuming. Particularly, it is required to proceed with the assembly of the liquid crystal module92in a dust-free environment having a spacious production space. However, the larger the area encompassed by the dust-free environment, the higher will be the cost of manufacture, operation and maintenance. Therefore, an improvement of the assembly procedure of the liquid crystal display device9is being sought by those in the industry.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a method for assembling a liquid crystal display device by directly assembling a front frame and optical components together so as to prevent contamination therebetween.

According to one aspect of the invention, a method for assembling a liquid crystal display device includes:

a) assembling together a front frame, a liquid crystal panel and an optical plate unit in a dust-free environment so as to form a first unit, the front frame being configured with an opening, the liquid crystal panel and the optical plate unit being disposed in sequence at one side of the front frame in a manner that the liquid crystal panel closes the opening in the front frame and that a sealed state is established between the liquid crystal panel and the optical plate unit, the optical plate unit having a light-entrance surface remote from the liquid crystal panel;

b) assembling a circuit board to one side of a rear frame without requirement of a dust-free environment so as to form a second unit;

c) assembling a light source to one of the first and second units; and

d) interconnecting fixedly the first and second units without requirement of a dust-free environment in a manner that the light source is able to provide light to the light-entrance surface of the optical plate unit.

Another object of the present invention is to provide a liquid crystal display device assembled according to the method of this invention.

According to another aspect of the invention, a liquid crystal display device comprises:

a front frame including a front frame plate formed with an opening, and a first surrounding wall that extends from one side of the front frame plate, the front frame plate and the first surrounding wall cooperating to define a first space;

a liquid crystal panel that is received in the first space and that closes the opening in the front frame plate;

an optical plate unit that has a light-entrance surface and a light-exit surface and that is received in the first space in a manner that the light-exit surface faces the liquid crystal panel, a periphery of the optical plate unit forming a tight relationship with the first surrounding wall, the weight of one of the optical plate unit and the liquid crystal panel acting on the other one of the optical plate unit and the liquid crystal panel such that the light-exit surface and the liquid crystal panel are in a tight relationship at least at peripheral portions thereof;

a rear frame that is connected to one end of the first surrounding wall of the front frame, and that includes a main plate;

a circuit board disposed on one side of the main plate opposite to the front frame; and

a light source disposed adjacent to the light-entrance surface for providing light toward the light-entrance surface.

A further object of the present invention is to provide a sub-assembly of the liquid crystal display device of this invention.

According to a further aspect of the invention, a sub-assembly of a liquid crystal display device comprises:

a front frame including a front frame plate formed with an opening, and a first surrounding wall that extends from one side of the front frame plate, the front frame plate and the first surrounding wall cooperatively defining a first space;

a liquid crystal panel that is received in the first space and that closes the opening in the front frame plate; and

an optical plate unit that has a light-entrance surface and a light-exit surface and that is received in the first space in a manner that the light-exit surface faces the liquid crystal panel, a periphery of the optical plate unit forming a tight relationship with the first surrounding wall.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 3, a first preferred embodiment of a method for assembling a liquid crystal display device according to the present invention is provided to illustrate assembly of a direct-light-type liquid crystal display (LCD) device100. Basically, two major parts of the LCD device100, i.e., a first unit200and a second unit300, are separately assembled.

Assembly of the first unit200is illustrated with reference toFIGS. 3 to 5. For convenience of illustration, a direction indicated by arrows in the accompanying drawings is a front direction. First, a front frame1is provided in a dust-free environment for assembling the first unit200. The front frame1includes a front frame plate11formed with an opening14, and a first surrounding wall12that extends backwardly from an inner periphery of the front frame plate11. The front frame plate11and the first surrounding wall12cooperate to define a first space13in spatial communication with the opening14. Then, a liquid crystal panel2and an optical plate unit3are disposed in the first space13in sequence, and are assembled together with the front frame1to form the first unit200as shown inFIG. 5. It should be noted that a thickness of the optical plate unit3is enlarged in the accompanying drawings to facilitate illustration of a relationship between the optical plate unit3and other components of the first unit200. The above-mentioned assembly sequence can be conducted in reverse, i.e., the liquid crystal panel2is stacked on the optical plate unit3, and then the front frame1is sleeved on the combination of the liquid crystal panel2and the optical plate unit3.

In this embodiment, as an example, the optical plate unit3includes an optical film31adjacent to the liquid crystal panel2, and a diffuser plate32that is remote from the liquid crystal panel2compared to the optical film31. One side (rear side) of the diffuser plate32remote from the optical film31is formed with a light-entrance surface33. One side (front side) of the optical film31facing the liquid crystal panel2is formed with a light-exit surface34. The light-exit surface34is substantially parallel and fittingly attached to the liquid crystal panel2, and the light-entrance surface33is substantially parallel to the light-exit surface34. Light enters the optical plate unit3through the light-entrance surface33, and is diffused by the diffuser plate32and homogenized or brightness-enhanced by the optical film31, and then enters the liquid crystal panel2through the light-exit surface34.

A periphery of the above-mentioned diffuser plate32and the first surrounding wall12are in a tight relationship with each other. Further, the liquid crystal panel2closes the opening14in the front frame plate11. Thus, a sealed state is established between the liquid crystal panel2and the optical plate unit3so as to prevent entry of contaminants therebetween. The tight relationship as called herein can be an interference fit. Since specifics of the interference fit can be readily appreciated by those skilled in the art, detail thereof will be omitted herein for the sake of brevity. The optical film31can be one of a brightness enhancement film, a prism sheet, and a diffuser film. The optical plate unit3can include a plurality of the optical films31. In addition, the optical film31may be omitted in other embodiments of the invention. It should be noted that the above-mentioned diffuser plate32is different from the diffuser film of the optical film31. The diffuser plate32is a relatively thick plate capable of supporting the optical film31and forming the tight relationship with the first surrounding wall12. In practice, aside from establishing the tight relationship between the diffuser plate32and the first surrounding wall12, it is also possible to establish a tight relationship between the light-exit surface34and the liquid crystal panel2, or to directly seal peripheries of the optical plate unit3and the liquid crystal panel2together using a sealant. For example, the weight of one of the optical plate unit3and the liquid crystal panel2acts on the other one of the optical plate unit3and the liquid crystal panel2such that the light-exit surface34and the liquid crystal panel2are in the tight relationship. Any manner that can establish the sealed state between the liquid crystal panel2and the optical plate unit3is applicable in the present invention. When the sealed state between the peripheries of the optical plate unit3and the liquid crystal panel2is established, the first surrounding wall12can have only two side walls for positioning, and may even be omitted in other embodiments of the invention.

Assembly of the second unit300is illustrated with reference toFIGS. 3,6and7. A rear frame4is provided. The rear frame4includes a main plate41, and a second surrounding wall42projecting from a front side of the main plate41. The main plate41and the second surrounding wall42cooperatively define a second space43. Then, a light source5, a reflective sheet6, the rear frame4, and a circuit board7are stacked and assembled in sequence to form the second unit300as shown inFIG. 7. The light source5and the reflective sheet6are received in the second space43. Similarly, the above-mentioned assembly sequence can be conducted in reverse, i.e., the rear frame4, the reflective sheet6, and the light source5are stacked on the circuit board7in sequence. Since the effect of particles on the light source5, the reflective sheet6, and the circuit board7in minimal, the second unit300can be assembled without requirement of a dust-free environment. That is, the second unit300can be assembled under normal environment conditions.

In this embodiment, the above-mentioned light source5includes a plurality of cold cathode fluorescent lamps51. The cold cathode fluorescent lamps51can be replaced by other illuminating components, such as light emitting diodes, in other embodiments of this invention. The circuit board7can be integrated with a power supply and a transformer (not shown). Additionally, a cover44can be further provided in a manner that the cover44covers the circuit board7for protecting the circuit board7. Further, the cover44can be pivotably disposed on a rear side of the main plate41.

Referring toFIGS. 3,5and7, after the first unit200and the second unit300are separately pre-assembled, one end of the first surrounding wall12of the front frame1and one end of the second surrounding wall42of the rear frame4are fixedly interconnected by adhering, interlocking, or using screws to form the LCD device100as shown inFIG. 3.

Concerning the above-mentioned assembly procedure, only the first unit200is assembled with a requirement of a dust-free environment. Regarding assembly of the second unit300and assembling the first and second units200,300together, there is no requirement of a dust-free environment. Moreover, the first unit200only involves assembling together the front frame1, the liquid crystal panel2, and the optical plate unit3. A required production space for the first unit200is relatively small, i.e., the dust-free environment for producing the LCD device100is not required to be as spacious as that for producing the conventional LCD device. Moreover, the present invention uses the front frame1and the rear frame4to assemble other components together. Compared with the conventional method, there is no requirement of an iron frame921and a plastic frame923(shown inFIG. 1). Even when the entire LCD device100is assembled in a dust-free environment, the required production space is still relatively small.

Referring toFIG. 8, a second preferred embodiment of the method for assembling a liquid crystal display device according to the present invention is provided to illustrate assembly of a side-light-type LCD device100′.

Assembly of the first unit200′ of this embodiment is illustrated first with reference toFIGS. 8 to 10. Components and the assembly method of the first unit200′ are generally similar to those of the first unit200of the first preferred embodiment. The difference resides in that the optical plate unit3′ includes an optical film31′ and a light-guiding plate35′. A periphery of the light-guiding plate35′ and the first surrounding wall12′ are in a tight relationship with each other. Further, the liquid crystal panel2′ closes the opening14′ in the front frame plate11′ of the front frame1′. Thus, a sealed state is similarly established between the liquid crystal panel2′ and the optical plate unit3′ so as to prevent entry of contaminant therebetween.

Moreover, the light-entrance surface33′ and the light-exit surface34′ of the optical plate unit3′ are different from the configuration of the first embodiment. The light-exit surface34′ is substantially parallel and fittingly attached to the liquid crystal panel2′, but the light-entrance33′ is substantially perpendicular to the light-exit surface34′ in this embodiment. An inner side of the first surrounding wall12′ adjacent to the light-entrance surface33′ is L-shaped, such that there is a clearance15′ between the light-entrance surface33′ and a part of the first surrounding wall12′ as shown inFIG. 10.

Assembly of the second unit300′ of this embodiment is illustrated with reference toFIGS. 8,11and12. Components and the assembly method of the second unit300′ are generally similar to those of the second unit300of the first preferred embodiment. The difference is that the light source5′ of this embodiment includes a fluorescent tube51′ and a reflective cover52′. Moreover, the light source5′ is not disposed on the reflective sheet6′ but between one side of the reflective sheet6′ and the second surrounding wall42′ of the rear frame4′, and a part of the light source5′ projects out of the second space43′. When the first unit200′ and the second unit300′ that are separately assembled are interconnected to form the LCD device100′ as shown inFIG. 8, a part of the light source5′ is received in the clearance15′ between the light-entrance surface33′ and the first surrounding wall12′, and the light source5′ is capable of providing light toward the light-entrance surface33′. Moreover, since the light source5′ of this embodiment provides light toward one side of the light-guiding plate35′, a bottom surface of the light-guiding plate35′ is an inclined surface (as shown inFIG. 10) to facilitate guiding of light. If the light source5′ includes a plurality of the fluorescent tubes51′ and the reflective covers52′, and provides light toward the light-guiding plate35′ from two or four sides of the latter, the bottom surface is preferably a horizontal surface. Since this can be readily appreciated by those skilled in the art, further details will be omitted herein for the sake of brevity.

Similarly, concerning the above-mentioned assembly procedure, only the first unit200′ is assembled with a requirement of a dust-free environment. Regarding assembly of the second unit300′ and assembling the first and second units200′,300′ together, there is no requirement of a dust-free environment. The second preferred embodiment can achieve the same effect as the first preferred embodiment.

In the following description, various modifications are provided for illustrating the present invention in more detail. First,FIGS. 13 and 14show a first modification that is similar to the second preferred embodiment. The only difference is that the light source5″ is not disposed in the second unit300″ but in the first unit200″, i.e., the light source5″ is disposed in the clearance15″ between the light-entrance surface33″ and the first surrounding wall12″ of the first unit200″. The second unit300″ is formed by assembling only the rear frame4″, the reflective sheet6″, and the circuit board7″ together. However, the first unit200″ and the second unit300″ that are separately assembled also form the LCD device100′ as shown inFIG. 8after they are interconnected. Similarly, the light source5of the first preferred embodiment can be disposed in the first unit200, and the first unit200and the second unit300also form the LCD device100as shown inFIG. 3after they are interconnected.

Besides the light source5″, the first surrounding wall12,12′,12″ and the second surrounding wall42,42′,42″ can also be modified. Referring toFIG. 3, since the first surrounding wall12and the second surrounding wall42are interconnected to form a unitary structure, the length of the first surrounding wall12can be lengthened to a total length of the first surrounding wall12and the second surrounding wall42, such that the second surrounding wall42may be omitted from the rear frame4. In this case, one end of the first surrounding wall12is disposed to abut against the main frame41when interconnecting the first unit200and the second unit300. In this case, the reflective sheet6is directly attached to the front side of the main plate41that is remote from the circuit board7.

Referring toFIG. 15, a second modification is illustrated and is a further modification of the first modification inFIGS. 13 and 14. In the modification ofFIG. 15, the optical film31″ and the light-guiding plate35″ are separated from each other. The light-guiding plate35″ and the light source5″ are disposed in a rear part (i.e., the second unit300″ inFIG. 14), and a diffuser plate32″ is additionally disposed rearwardly of the optical film31″. The diffuser plate32″ and the first surrounding wall12″ are in the tight relationship (already described in the first preferred embodiment) so as to fix the optical film32″ and the liquid crystal panel2″.

Referring toFIG. 16, in a third modification, an inner surface of the first surrounding wall12inFIG. 5is configured to be step-shaped and cooperates with a pressing strip8to prevent entry of contaminants.

In particular, the inner surface of the first surrounding wall12is a step-shaped surface that converges in a direction toward the front frame plate11. In this modification, the inner surface of the first surrounding wall12has three steps as an example, i.e., the inner surface has a first step surface section121, a second step surface section122, and a third step surface section123. The liquid crystal panel2is disposed to abut against the first step surface section121, and the optical plate unit3is disposed to abut against the second step surface section122. Moreover, in this modification, another scheme is used to establish the sealed state between the liquid crystal panel2and the optical plate unit3, i.e., the pressing strip8is disposed around the third step surface section123. A part of the pressing strip8covers a periphery of the optical plate unit3, and a plurality of screws80(only one is shown inFIG. 16) pass through the pressing strip8for fastening the pressing strip8on the third step surface section123to thereby press the optical plate unit3. The optical plate unit3then presses the liquid crystal panel2to thereby prevent entry of contaminants between the liquid crystal panel2and the optical plate unit3.

In practice, it is feasible to dispose the screws80such that they are able to pass through both the pressing strip8and the optical plate unit3to thereby fasten both on the second step surface section122. The pressing strip8can be omitted, and the optical plate unit3can be fastened on the second step surface section122directly via the screws80to prevent entry of contaminants as shown inFIG. 17. In this case, the third step surface section123can be omitted.

Referring toFIG. 18, in a fourth modification, there is provided a configuration where the liquid crystal panel2does not contact the optical plate unit3to reduce the possibility of the liquid crystal panel2scraping the surface of the optical film31.

The difference between the third modification inFIG. 16and the fourth modification inFIG. 18is that there is a clearance20between the liquid crystal panel2and the optical film31to separate the optical film31from the liquid crystal panel2. Moreover, in order to transmit a pressure provided by the pressing strip8for fastening, a buffer30is disposed in the clearance20in a manner that two opposite sides of the buffer30abut against the liquid crystal panel2and the optical plate unit3, respectively. Therefore, an effect of preventing entry of contaminants between the liquid crystal panel2and the optical film31can be achieved. Of course, if each of the liquid crystal panel2and the optical film31is in a tight relationship with the first surrounding wall12, the buffer30can be omitted.

In regard to a material of the buffer30, the buffer30is made of polyethylene terephthalate as an example. However, other siloxane or foam may be used.

Referring toFIG. 19, a fifth modification is an integrated design of the first modification inFIG. 13and the fourth modification inFIG. 18. In this case, the light source5″ including the fluorescent tube51″ and the reflective cover52″ is disposed on the second step surface section122adjacent to the optical plate unit3. The pressing strip8and the screws80are used for pressing and fastening so as to prevent entry of contaminants.

Referring toFIG. 20, a sixth modification provides the front frame1inFIG. 5with a protective frame10sleeved on one side of the front frame plate11of the front frame1opposite to the first surrounding wall12for protecting the front frame1. When the protective frame10is worn out, it can be readily replaced with a new one. The protective frame10can be designed as a particular configuration, such as an animal form, for decorative purposes.

Referring toFIG. 21, in a seventh modification, one side (front side) of the main plate41of the rear frame4facing toward the second space43is a flat surface45. The reflective sheet (not shown) can be attached to the flat surface45, or the flat surface45can be coated with a reflective coating material to thereby omit the need of the reflective sheet. Aside from coating the reflective coating material on the flat surface45, the same effect can be achieved if the rear frame4is made of a material capable of reflecting light.

Referring toFIG. 22, in an eighth modification, one side of the main plate41of the rear frame4remote from the second surrounding wall42is formed with a groove46. The circuit board (not shown) is disposed in the groove46, and the cover (not shown) is designed to be capable of covering the groove46for protecting the circuit board. Moreover, a bottom surface of the groove46is provided with a plurality of fastener parts47for fastening the circuit board to the rear frame4.

Moreover, it should be noted that, besides being applicable to the manufacture of the LCD device, the method of the present invention can be also applied in the manufacture of a liquid crystal module. Similarly, two major parts, i.e., a first unit810(shown inFIG. 23) and a second unit820(shown inFIG. 24), are separately assembled.

In the following description, there is described a liquid crystal module manufactured using a method similar to the method of the first preferred embodiment (direct-light-type). First, referring toFIG. 23, a module front frame8is provided in a dust-free environment for assembling the first unit810. The module front frame8includes a front frame plate81formed with an opening84, and a first surrounding wall82that extends backwardly from an inner periphery of the front frame plate81. The front frame plate81and the first surrounding wall82cooperate to define a first space83in spatial communication with the opening84. Then, a liquid crystal panel2and an optical plate unit3(including an optical film31and a diffuser plate32) are disposed in the first space83in sequence, and are assembled together with the module front frame8to form the first unit810similar to the first unit200shown inFIG. 5.

Then, referring toFIG. 24, a rear frame4is provided for assembling the second unit820. The rear frame4includes a main plate41, and a second surrounding wall42projecting from a front side of the main plate41. The main plate41and the second surrounding wall42cooperatively define a second space43. Then, a light source5, a reflective sheet6, and the rear frame4are assembled in sequence to form the second unit820similar to the second unit300shown inFIG. 7.

After the first unit810and the second unit820are separately assembled, the first unit810and the second unit820can be further assembled together to form a liquid crystal module830as shown inFIG. 25. The procedure for assembling the liquid crystal module830is the same as that described in the first preferred embodiment, and will not be repeated herein for the sake of brevity. Regarding this assembly method, only the first unit810is assembled with a requirement of a dust-free environment. Moreover, the module front frame8replaces the iron frame921and the plastic frame923(shown inFIG. 1), such that the entire production procedure is simplified compared to the prior art.

Referring toFIG. 26, it should be noted that the design of the rear frame4of the second unit820is slightly different. Compared with the rear frame inFIG. 22, the design of the groove46is omitted, and a circuit board can be mounted directly using the fastener parts47.

Moreover, each of the LCD devices100,100′ and the liquid crystal module830can be further combined with other electronic devices to form various electronic systems. Referring toFIG. 27, as an example, the LCD device100can be combined with a computer host device710to form a computer system700. The computer host device710includes a processing unit712. The LCD device100is electrically connected to the host device710and is controlled by the processing unit712to show images thereon in a known manner. Referring toFIG. 28, the LCD device100can be combined with a control module610to form a liquid crystal television600. The control module610includes a video interface611for receiving or outputting a signal, and a processing unit612for processing the signal. The LCD device100is electrically connected to the control module610, and shows images thereon in a known manner.

Of course, the above-mentioned procedure can also refer to the method of the second preferred embodiment to assemble a side-light-type liquid crystal module. The relevant details will be omitted herein for the sake of brevity.

In conclusion, the method for assembling a LCD device of the present invention includes four major steps as shown inFIG. 29.

Further referring toFIGS. 5,10and13, step (S1) is to assemble together the front frame1,1′,1″, the liquid crystal panel2,2′,2″ and the optical plate unit3,3′,3″ in a dust-free environment so as to form the first unit200,200′,200″. The front frame1,1′,1″ is configured with the opening14,14′,14″. The liquid crystal panel2,2′,2″ and the optical plate unit3,3′,3″ are disposed in sequence at one side of the front frame1,1′,1″ in a manner that the liquid crystal panel2,2′,2″ closes the opening14,14′,14″ in the front frame1,1′,1″ and that a sealed state is established between the liquid crystal panel2,2′,2″ and the optical plate unit3,3′,3″. The optical plate unit3,3′,3″ has a light-entrance surface33,33′,33″ remote from the liquid crystal panel2,2′,2″.

Referring toFIGS. 7,12,14and29, step (S2) is to assemble the circuit board7,7′,7″ to one side of a rear frame4,4′,4″ without requirement of a dust-free environment so as to form a second unit300,300′,300″.

Referring toFIGS. 7,12,13and29, step (S3) is to assemble a light source5,5′,5″ to the first unit200″ or the second unit300,300′.

Referring toFIGS. 3,8and29, step (S4) is to interconnect fixedly the first unit200,200′,200″ and the second unit300,300′,300″ without requirement of a dust-free environment in a manner that the light source5,5′,5″ is able to provide light to the light-entrance surface33,33′,33″ of the optical plate unit3,3′,3″.

In sum, in the method for assembling a LCD device of the present invention, the front frame1,1′,1″ is used for pre-assembling the liquid crystal panel2,2′,2″ and the optical plate unit3,3′,3″ to form the first unit200,200′,200″ in a dust-free environment in a manner that a sealed state is established between the liquid crystal panel2,2′,2″ and the optical plate unit3,3′,3″. Then, the rear frame4,4′,4″, the reflective sheet6,6′,6″, and the circuit board7,7′,7″ are assembled together to form the second unit300,300′,300″ without requirement of a dust-free environment. The light source5,5′,5″ is assembled to the first unit200,200′,200″ or the second unit300,300′. Finally, the first unit200,200′,200″ and the second unit300,300′,300″ are assembled together to form the LCD device100,100′. The part assembled with a requirement of a dust-free environment and the other part assembled without requirement of a dust-free environment can be separately assembled. Therefore, the objects of the present invention can be positively achieved.