Abstract:
A hinge assembly for pivotably connecting the display portion and the body portion of the portable computer comprises a first fastening portion for attaching to the display portion, a second fastening portion for attaching to the body portion, and a pivot portion for pivotably connecting the first fastening portion with the second fastening portion. The second fastening portion also has a first support arm for horizontally inserting into the insertion hole. The cables, for transmitting signals and power extending from the display portion, are electrically connected through connectors to the cable connection region. The cable connect region is formed on the rear wall or bottom wall of the body portion. The hinge assembly of the invention greatly reduces the extraordinary sound resulting from the rotation of the display portion. Also, some covering components can be eliminated to make the assembly much easier.

Description:
This application incorporates by reference of Taiwan application Serial No. 90213251, filed Aug. 3, 2001. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to an apparatus for supporting a monitor, and more particularly to an apparatus for supporting a liquid crystal display (LCD) and rotating the LCD with respect to the base. 
     2. Description of the Related Art 
     In order for a monitor, such as a liquid crystal display (LCD), to be rotated forward and backward, the supporting apparatus of the monitor or the LCD need an angle adjustment design. Generally, the apparatus for supporting the LCD comprises a supporting arm for leading the rotation of LCD, wherein the supporting arm is fastened to the lower side of LCD. 
       FIG. 1A  is a side view of a conventional apparatus for supporting the LCD. The conventional apparatus for supporting the LCD comprises a shaft  102 , the angle control elements  104   a  and  104   b , and the clasps  106   a  and  106   b  mounted on the shaft  102 . Additionally, a pedestal  108  is provided for the apparatus for supporting the LCD. During assembly, the assembled shaft  102  is inserted through the holes of the pedestal  108  and the supporting frame  110 , and then secured by the screw caps  112   a  and  112   b . The frictional torques on the two ends of the shaft  102  are produced, due to the rotation of apparatus, and the magnitudes thereof are different. For example, one end of shaft  102  (close to the screw cap  112   a ) produces 45 kg/m of frictional torque, and the other end (close to the screw cap  112   b ) produces 25 kg/m of frictional torque. Also, the shaft  102  is a combination of sectional cores; for example, two cores are respectively situated in the right and left sides of the angle control element  104   a . The supporting frame  110  embedded in a supporting arm can be rotated in a small angle range by gently applying an external force; meanwhile, the whole shaft  102  is rotated with respect to the supporting frame  110 . If greater external force is applied to the supporting frame  110 , the supporting frame  110  can be rotated to a larger angle; meanwhile, only one core is rotated with respect to the supporting frame  110  and the other core is sustained in the stationary state. 
     FIG.  1 B and  FIG. 1C  are side views of the angle control elements in FIG.  1 A. It is assumed that the LCD can be rotated in the range of 2 degrees forward and 60 degrees backward. There is a cut on the upper edge of the angle control element  104   a , as shown in FIG.  1 B. The cut, divided by the central line (dash line), is split into a 2-degree angle and a 20-degree angle. There is a cut on the lower edge of the angle control element  104   b , as shown in FIG.  1 C. The cut, divided by the central line (dash line), is split into two 60-degree angles. When the supporting frame  110  of the LCD is vertical to the base, the central lines of the angle control elements  104   a  and  104   b  are parallel to the clasps  106   a  and  106   b , respectively. When the LCD is rotated, the shaft  102  is rotated with respect to the supporting frame  210 , and the clasps  106   a  and  106   b  respectively slide along the cuts of the angle control elements  104   a  and  104   b . When the clasps  106   a  and  106   b  hit the risen edges of the angle control elements  104   a  and  104   b , rotation of the supporting frame  110  stopped. If the supporting frame is rotated in the range of 2 degrees forward to 20 degrees backward, the whole shaft  102  is driven. If it is desired to rotate the supporting frame  110  to 60 degrees backward, then a larger force is needed for driving the shaft core at the left side of the angle control element  104   a ; meanwhile, the shaft core at the right side of the angle control element  104   b  is sustained, and the clasp  106  keeps sliding along the edge of the cut of the angle control element  104   b  until hitting the risen edge thereof. 
     According to the description above, the conventional apparatus for supporting the LCD has a drawback of highly cost due to the combination of the two sectional cores. In addition, magnitude of the frictional torques on the two ends of the shaft  102  are different, the end of the shaft  102  producing less frictional torque being weaker than the other end and easier to be damaged. Also, manual adjustment for adjusting the produced torques is required during assembly. It is time-consuming and labor-intensive. If the diameter of the core is increased for bearing the larger external force, the size of the apparatus for supporting the LCD also increases. Additionally, a pedestal is required on which the apparatus for supporting the LCD is mounted, thereby restricting the potential for developing a lighter and smaller base of the monitor. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an apparatus for supporting a monitor, in which the mechanical apparatus to rotate the monitor with respect to the base has great position effect, and the durability of the components of the apparatus is improved because the components are not easy to be aged. 
     According to the objective of the invention, an apparatus for supporting a monitor is provided, wherein the monitor connected to the base is rotatable. The apparatus comprises a supporting frame, a latching assembly, and a shaft assembly, wherein the latching assembly and the shaft assembly are mounted on the supporting frame. The supporting frame has a first sidewall and a second sidewall. The latching assembly comprises a tenon, wherein two ends of the tenon are a protrusive portion and a conjunctive portion. Between the protrusive portion and the conjunctive portion is the main body of the tenon. The protrusive portion projects through the second tenon hole of the second sidewall. Also, a control bar connected to the tenon is used for driving the tenon. The shaft assembly comprises a rotation control unit, a shaft base, and a plurality of washers. There are a first U-shaped cut and a second U-shaped cut in the edge of the rotation control unit. When the supporting frame is rotated, the protrusive portion slides along the edge of the first U-shaped cut and the hook slides along the edge of the second U-shaped cut, so that the monitor can be rotated in a first angle range. By moving the control bar, the protrusive portion will not couple to the first U-shaped cut and move toward the interior of the supporting frame, so that the monitor can be rotated in a second angle range. 
     According to the objective of the invention, another apparatus for supporting a monitor is provided, comprising a supporting frame, a lock assembly, and a shaft assembly. The supporting frame has a first sidewall and a second sidewall. The lock assembly comprises a lock pin and a spring. The ends of the lock pin are a protrusive portion and a conjunctive portion for receiving the spring. The spring is used for providing elastic recover force acting on the protrusive portion, so as to project the protrusive portion behind the second sidewall. There are a first U-shaped cut and a second U-shaped cut in the edge of the rotation control unit. The protrusive portion is coupled to the surface of the rotation control unit. The hook couples to the second U-shaped cut. When the supporting frame is rotated, the protrusive portion slides along a surface of the rotation control unit and the hook slides along the edge of the second U-shaped cut, so that the monitor can be rotated in a first angle range. When the supporting frame is rotated to a predetermined angle, the lock pin is pushed by the elastic recover force of the spring, so as to project the protrusive portion behind the second sidewall. If the supporting frame is further rotated, the protrusive portion is consequently uncoupled from the first cut, so that the monitor can be rotated in a second angle range. 
     Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  (prior art) is a side view of a conventional apparatus for supporting the LCD; 
       FIG.  1 B and  FIG. 1C  (prior art) are side views of the angle control elements in  FIG. 1A ; 
         FIG. 2A  is a perspective view of the LCD assembled with the apparatus for supporting the monitor according to the first embodiment of the invention; 
         FIG. 2B  is a side view of the LCD assembled with the apparatus for supporting the monitor according to the first embodiment of the invention; 
         FIG. 3A  is a disassembled view of the apparatus for supporting the monitor according to the first embodiment of the invention; 
         FIG. 3B  is a perspective view of the tenon of  FIG. 3A ; 
         FIG. 3C  is a front view of the rotation control unit of  FIG. 3A ; 
         FIG. 3D  shows the ranges of the angles of the rotation control unit of  FIG. 3A ; 
         FIG. 3E  is a perspective view of the shaft base of  FIG. 3A ; 
         FIG. 3F  is a perspective view of the washers of  FIG. 3A ; 
         FIG. 4A  is a perspective view of the assembled apparatus for supporting the monitor according to the first embodiment of the invention, while the LCD is vertical to the base; 
         FIG. 4B  is a side view of the apparatus of  FIG. 4A ; 
         FIG. 5A  is a perspective view of the assembled apparatus for supporting the monitor of the invention, while the LCD with the retracted is protrusive portion of the tenon is tilted backward at 25 degrees; 
         FIG. 5B  is a side view of the apparatus of  FIG. 5A ; 
         FIG. 6A  is an enlarged perspective view of the apparatus for supporting the monitor according to the second embodiment of the invention; 
         FIG. 6B  is a perspective view of the lock pin of  FIG. 6A ; 
         FIG. 6C  is a front view of the rotation control unit of  FIG. 6A ; 
         FIG. 6D  shows the angles of the rotation control unit of  FIG. 6A ; 
         FIG. 7A  is a perspective view of the assembled apparatus for supporting the monitor according to the second embodiment of the invention, while the LCD is vertical to the base; 
         FIG. 7B  is a side view of the apparatus of  FIG. 7A ; 
         FIG. 8A  is a perspective view of the assembled apparatus for supporting the monitor according to the second embodiment of the invention, while the LCD is tilted backward to 25 degrees; and 
         FIG. 8B  is a side view of the apparatus of FIG.  8 A. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The apparatus for supporting a monitor of the invention, particularly for connecting the liquid crystal display (LCD) and the base, allows the mechanical pivoting of the LCD on the base within a certain range. Also, the invention is further designed so that the LCD equipped with the apparatus can be folded to 90 degrees, for increased portability. In the preferred embodiments, the LCD rotating in the range of 2 degrees forward to 25 degrees backward and further folding to 90 degrees is taken for illustration. In the first embodiment (example 1), the purpose of positioning the LCD is achieved by cooperation of a rotation control unit and a tenon. In the second embodiment (example 2), the purpose of positioning the LCD is achieved by cooperation of a rotation control unit and a lock pin. 
     In the following description, the preferred examples are taken for illustrating the invention, but the invention is not limited hereto. Also, to avoid obscuring the invention, well-known elements not directly relevant to the invention are not shown nor described. Accordingly, the specification and the drawing are to be regarded in an illustrative sense rather than a restrictive sense. 
     EXAMPLE 1 
       FIG. 2A  is a perspective view of an LCD assembled with the apparatus for supporting the monitor according to the first embodiment of the invention. In  FIG. 2A , the LCD  202  is connected to the base  204  by two supporting arms  206   a  and  206   b .  FIG. 2B  is a side view of the LCD assembled with the apparatus for supporting the monitor according to the first embodiment of the invention. In  FIG. 2B , the LCD is tilted forward, away from the vertical central line  212 , and positioned in the first angle  214  (set up as 2 degrees herein). The LCD is tilted backward away from the vertical central line  212  and positioned in the second angle  216  (set up as 25 degrees herein). Also, the LCD can be folded backward to 90 degrees, which is in parallel with the base  204 . A belt-shaped portion is further created in the base  204 , so that the user can easily carry the LCD by holding the belt-shaped portion  204   a . The apparatus for supporting a monitor is equipped inside the supporting arm  206   a  or  206   b . The supporting arm  206   a  (or  206   b ) is assembled by two housings  207   a  and  207   b , one side of which the engaging housings  207   a  and  207   b  are screwed by a fastening cover  208  to ensure the fixing thereof. The details of the apparatus for supporting a monitor of the invention are illustrated below. 
       FIG. 3A  is a disassembled view of the apparatus for supporting the monitor according to the first embodiment of the invention. The apparatus for supporting the monitor comprises a latching assembly  302  and a shaft assembly  304  coupled to a supporting arm  210 . The latching assembly  302  includes a tenon  312 , a spring  314 , and a control bar  332 .  FIG. 3B  is a perspective view of the tenon of FIG.  3 A. In  FIG. 3B , one end of the tenon  312  has a protrusive portion  344  while the other end has a conjunctive portion  342 , according to their operating functions. Between the protrusive portion  344  and the conjunctive portion  342  is the main body  346  of the tenon  312 . 
     The shaft assembly  304  includes a rotation control unit  306 , a shaft base  308 , a plurality of washers  310 , and a screw  318 .  FIG. 3C  is a front view of the rotation control unit of FIG.  3 A. The rotation control unit  306  is a metallic plate with the U-shaped cuts. There are a first U-shaped cut  3061  and a second U-shaped cut  3062  formed in the edge of the rotation control unit  306 ; also a central opening  3063  is formed in the center of the rotation control unit  306 . The first U-shaped cut  3061  is created to control the rotation angle of the LCD, so as to enable the LCD to tilt in the range of 2 degrees forward and 25 degrees backward. The second U-shaped cut  3062  is created for enabling the LCD to tilt in the range of 2 degrees forward and 90 degrees backward.  FIG. 3D  shows the ranges of the angles of the rotation control unit of FIG.  3 A. 
       FIG. 3E  is a perspective view of the shaft base of FIG.  3 A. One end of the shaft base  308  has a conjunctive portion  3081 , and a number of threads  3082  are formed on the top of the conjunctive portion  3081 . The rotation control unit  306  and the washers  310  fit onto the conjunctive portion  3081  of the shaft base  308 . Additionally, there are two threaded holes  3083   a  and  3083   b  on the other end of the shaft base  308 , associated with another threaded holes on the LCD base  204 , for securing the shaft base  308  on the base  204  by the use of a bolt. When the LCD  202  rotates with the base  204  (see FIG.  2 ), the supporting frame  210  rotates with the shaft base  308  accordingly. 
     Additionally, a number of washers  310  are designed for releasing the friction between the rotation control unit  306  and the shaft base  308 , and also for providing the frictional torque.  FIG. 3F  is a perspective view of the washers of FIG.  3 A. The washers  310  illustrated in an order from left to right are: a fix washer  320 , a torque washer  322 , two spring washers  324   a  and  324   b , and three torque washers  326 ,  328   a , and  328   b . For achieving the objective of smooth rotation and long-term durability, seven washers are preferably used in example 1; however, the invention is not limited herein. The number and composition of the washers may be selectively varied to accommodate a wide range of LCD panel sizes, weights, and degrees of mass unbalance. 
     The circular holes are formed on the sidewalls of the supporting frame  210 , in which the latching assembly  302  and the shaft assembly  304  are coupled. As shown in  FIG. 3A , the supporting frame  210  includes a first sidewall  220  and a second sidewall  230 . A first tenon hole  336   a  and a second tenon hole  336   b  are formed on the first sidewall  220  and the second sidewall  230 , respectively. A shaft hole  338  is formed next to the second tenon hole  336   b . Also, a hook  340  situated in the lower end of the second sidewall  230  projects outward. The latching assembly  302  is mounted on the supporting frame  210  through the first tenon hole  336   a  and the second tenon hole  336   b . The shaft assembly  304  is mounted on the supporting frame  210  through the shaft hole  338 . The hook  340  slides along the second U-shaped cut  3062  of the rotation control unit  306 . When the hook  340  hits the risen edge of the second U-shaped cut  3062 , the supporting frame  210  stops moving, and consequently the LCD stops rotating. 
     In the foregoing description, the components of the apparatus for supporting a monitor, such as the washers, the tenon, the supporting frame, and the rotation control unit, are hardened by thermo-treatment. The hardened components, not easy to be aged and broken, are employed to ensure that the applied LCD can be stably rotated in frequent use. 
     During assembly, the conjunctive portion  3081  of the shaft base  308  is inserted through the central opening  3063  of the rotation control unit  306 , the shaft hole  338 , and the washers, and then is secured on the second sidewall  230  of the supporting frame  210  by a fastener, such as a screw  318 . It is noted that the opening of the fix washer  320  and the cross section of the conjunctive portion  3081  are not circular, but tangent to the shaft hole  338  and the openings of other washers. Next, the spring  314  slides on the conjunctive portion  342  of the tenon  312 . The tenon  312  is then mounted between the first tenon hole  336   a  and the second tenon hole  336   b , wherein the protrusive portion  344  is projected beyond the second sidewall  230 . 
     Also, the control bar  332 , inserted through the control slot  350  of the control bracket  334 , is situated on the main body of the tenon  346  and can be moved along the control slot  350  by the user. When the control bar  322  is not pushed by an external force, the protrusive portion  344  projects beyond the second sidewall  230  and is coupled with the first U-shaped cut  3061 . When the control bar  322  is moved toward the left hand side (FIG.  3 A), the protrusive portion  344  is consequently moved toward the inner of the supporting frame  210  and compresses the spring  314 . Therefore, the protrusive portion  344  can be removed from the first U-shaped cut  3061  by the movement of the control bar  332 . 
     Subsequently, the two housings  207   a  and  207   b , which have almost symmetrical structures, are engaged together so that the supporting frame  210  and the other components mounted thereon can be fully enclosed. Then, one side of the engaging housings  207   a  and  207   b  are screwed by a fastening cover  208  to complete the assembly. 
     The following description and related drawings illustrate the operation of the apparatus for supporting a monitor according to the first embodiment of the invention. It is assumed that the LCD monitor is rotated in the range of +2 degrees (tilted forward 2 degrees from the vertical line) to −25 degrees (tilted backward 25 degrees from the vertical line), and also folded to an angle of 90 degrees. 
       FIG. 4A  is a perspective view of the assembled apparatus for supporting the monitor according to the first embodiment of the invention, while the LCD is vertical to the base.  FIG. 4B  is a side view of the apparatus of FIG.  4 A. The front surface  402  of the supporting frame  210  is a plane for attaching the LCD (not shown). In FIG.  4 A and  FIG. 4B , the front surface  402  is parallel to the LCD and y-axis, and the base of the LCD is parallel to x-axis. It is defined that the angle of rotation is 0 degree while the LCD is vertical to the base. Meanwhile, the protrusive portion  344  of the tenon  312  and the hook  340  are coupled with the first U-shaped cut  3061  and the second U-shaped cut  3062  of the rotation control unit  306 , respectively. Without application of an external force, the control bar  332 , projected beyond the control bracket  334 , stays in the right position of the control slot  350  (close to the second sidewall  230  of the supporting frame  210 ), and consequently the protrusive portion  344  projects beyond the second tenon hole  336   b . If the LCD is rotated, then the shaft base  308  and the rotation control unit  306  are not able to rotate, but the supporting frame  210 , the latching assembly  302  and the washers can rotate around the shaft base  308 ; therefore, the protrusive portion  344  and the hook  340  slide along the edges of the first U-shaped cut  3061  and the second U-shaped cut  3062  of the rotation control unit  306 , respectively. 
     Simply saying, when the LCD is rotated toward the direction of F 1  (see FIG.  4 B), the protrusive portion  344  and the hook  340  respectively slide along the edges of the first U-shaped cut  3061  and the second U-shaped cut  3062  of the rotation control unit  306  in the direction of F 1 . If the LCD is rotated toward the direction of F 2 , the protrusive portion  344  and the hook  340  are moved toward the direction of F 2 . 
     When the protrusive portion  344  hits the risen edge of the first U-shaped cut  3061  of the rotation control unit  306 , the LCD stops rotating and is positioned at an angle of 25 degrees. If the rotation of LCD from the angle of 25 degrees to 90 degrees is desired, the protrusive portion  344  must be removed from the top of the first U-shaped cut  3061 .  FIG. 5A  is a perspective view of the assembled apparatus for supporting the monitor of the invention, while the LCD with the retracted protrusive portion of the tenon is tilted backward to 25 degrees.  FIG. 5B  is a side view of the apparatus of FIG.  5 A. It is clearly shown in  FIG. 5A  that the protrusive portion  344  is retracted away from the first U-shaped cut  3061  by moving the control bar  332  toward the second sidewall  220 . The LCD can be folded to the angle of 90 degrees; meanwhile, the protrusive portion  344  slides against the rear surface of the rotation control unit  306 . 
     In accordance with the description above, it is apparently indicated that the tilt angle of the LCD is determined by the sizes of the first U-shaped cut  3061  and the second U-shaped cut  3062  of the rotation control unit  306 . However, the tilt angle of the invention is not limited in the range of 2 degrees forward to 25 degrees backward, and the fold angle, to 90 degrees. According to the practical application of the invention, the size of the first U-shaped cut  3061  is substantially associated with the first angle range, and the size of the second U-shaped cut  3062  is substantially associated with the second angle range. 
     Additionally, the apparatus for supporting a monitor can be further designed to rotate the LCD only in the first angle range, such as 2 degrees forward to 25 degrees backward, without the 90-degree folding design. Accordingly, the latching assembly  302  can be replaced with a protruding element so that the protruding element slides along the edge of the first U-shaped cut  3061 . For example, the control bar  332  can be eliminated, or the latching assembly  302  is replaced with the protruding element, which is formed on the position of the second tenon hole  336   b  on the second sidewall  230 . The protruding element could be the original protrusive portion  344 , or a protruding element integrated with the supporting frame  210  as a whole. 
     It has been repeatedly tested by test engineers, and demonstrated that the mechanical apparatus for supporting a monitor of the invention has better position effect than the conventional supporting apparatus. Also, the LCD equipped with the apparatus for supporting a monitor of the invention is not easy to be aged, and the durability thereof is highly increased. Additionally, the overall size of the apparatus for supporting a monitor of the invention is much smaller, so that the space for connecting the LCD and the base can be decreased. 
     EXAMPLE 2 
     In this second embodiment, the structure and components are similar to those of the first embodiment. Generally, the purpose of positioning the LCD is achieved by cooperation of a rotation control unit with cuts, a lock assembly, and a hook. The details are illustrated below. 
       FIG. 6A  is a disassembled view of the apparatus for supporting the monitor according to the second embodiment of the invention. In the second embodiment, the apparatus for supporting a monitor comprises a supporting frame  410 , a lock assembly  502 , and a shaft assembly  504 . The lock assembly  502  includes a lock pin  512  and a couple ring  516 .  FIG. 6B  is a perspective view of the lock pin of FIG.  6 A. One end of the lock pin  512  has a protrusive portion  544 , and the other end has a conjunctive portion  542 . 
     The shaft assembly  504  includes a rotation control unit  506 , a shaft base  508 , a plurality of washers  510 , and a screw  518 .  FIG. 6C  is a front view of the rotation control unit of FIG.  6 A. The rotation control unit  506  is a metallic plate with the U-shaped cuts. There are a first U-shaped cut  5061  and a second U-shaped cut  5062  formed in the edge of the rotation control unit  506 ; also a central opening  5063  is formed in the center of the rotation control unit  506 . When the LCD is rotated backward to an angle of 25 degrees, the protrusive portion  544  of the lock pin  512  couples to the first U-shaped cut  5061 . The second U-shaped cut  5062  functions in the same manner as in the first embodiment, for rotating the LCD in the range of 2 degrees forward to 90 degrees backward.  FIG. 6D  shows the said angles of the rotation control unit of FIG.  6 A. 
     Additionally, a number of washers  510  are designed for releasing the friction between the rotation control unit  506  and the shaft base  508 , and also for providing the frictional torque. In  FIG. 6A , the washers  510 , illustrated in an order from left to right, are: a fix washer  520 , a rotation control washer  522 , and four spring and torque washers  524   a ,  524   b ,  524   c , and  524   d . For achieving the objective of smooth rotation and long-term durability, six washers are preferably used in example 2; however, the number and composition of the washers may be selectively varied to accommodate a wide range of LCD panel sizes, weights, and degrees of mass unbalance. Also, the shaft base  508  has a conjunctive portion  5081 , and the rotation control unit and the washers are mounted thereon. Also, there are threaded holes on the other end of the shaft base  508 , associated with another threaded holes on the LCD base  204 , for securing the shaft base  508  on the base  204  by the use of a bolt. 
     The supporting frame  410  includes a first sidewall  420  and a second sidewall  430 . A first lock pin hole (not shown) and a second lock pin hole  536   b  are formed on the first sidewall  420  and the second sidewall  430 , respectively. Both lock pin holes are provided for mounting the lock assembly  502 . Also, a shaft hole  538  is formed next to the second lock pin hole  536   b.    
     During assembly, the conjunctive portion  5081  of the shaft base  508  is inserted through the central opening  5063  of the rotation control unit  506 , the shaft hole  538 , the washers, and then secured on the second sidewall  430  of the supporting frame  410  by a screw  518 . It is noted that the opening of the fix washer  520  and the cross section of the conjunctive portion  5081  are not circular, but tangent to the shaft hole  538  and the openings of other washers. Next, the spring  514  slides on the conjunctive portion  542  of the lock pin  512 . The lock pin  512  is then mounted between the first lock pin hole and the second lock pin hole  536   b , and secured by a couple ring  516  such as a E type ring. After assembly, the protrusive portion  544  projects beyond the second sidewall  430  by the elastic force of the spring  514 . Subsequently, the two housings  207   a  and  207   b  and the fastening cover  208  are engaged together so as to fully enclose the supporting frame  210  and the other components. 
     When the supporting frame  410  is rotated, the protrusive portion  544  of the lock pin  512  moves against the back surface of the rotation control unit  506 . While the supporting frame  410  is rotated to a predetermined angle; for example, in a 25-degree tilt backward from the vertical central line, the protrusive portion  544  couples to the first U-shaped cut  5061 . Also, a hook  540  situated in the lower edge of the rotation control unit  522 . The hook  540  slides along the second U-shaped cut  5062  of the rotation control unit  506 , and stops moving when the hook  540  hits the risen edge of the second U-shaped cut  5062 , such as point e or point f shown in FIG.  6 C. Additionally, the fix washer  520  of  FIG. 6A  further has a clasp  560 , which the clasp  560  is coupled to the fix cut  550  ( FIG. 6C ) on the edge of the rotation control unit  506 . 
       FIG. 7A  is a perspective view of the assembled apparatus for supporting the monitor according to the second embodiment of the invention, while the LCD is vertical to the base.  FIG. 7B  is a side view of the apparatus of FIG.  7 A. The front surface  602  of the supporting frame  410  is a plane for attaching the LCD (not shown in FIG.  7 B). In  FIG. 7B , the front surface  602  is parallel to the LCD and y-axis, and the base, of the LCD is parallel to x-axis. While the LCD is vertical to the base, the protrusive portion  544  of the lock pin  512  is against the back surface of the rotation control unit  506 , and the spring  514  is therefore compressed, as shown in FIG.  7 A. Also, the hook  540  actively couples to the second U-shaped cut  5062  of the rotation control unit  506 . Simply saying, if the LCD is rotated from the vertical state to 25 degree backward, the protrusive portion  544  slides against the back surface of the rotation control unit  506 , while the hook  540  slides from the point e to point f ( FIG. 6C ) of the second U-shaped cut  5062 . 
       FIG. 8A  is a perspective view of the assembled apparatus for supporting the monitor according to the second embodiment of the invention, while the LCD is tilted backward to 25 degrees.  FIG. 8B  is a side view of the apparatus of FIG.  8 A. When the LCD is rotated backward to a predetermined angle such as 25 degrees, the protrusive portion  544  exactly couples to the first U-shaped cut  5061 . Meanwhile, the elastic recovery force of the spring  514  acts on the lock pin  512 , so that the lock pin  512  is projected beyond the first U-shaped cut  5061 , and the rotation of LCD is stopped. Since the lock pin  512  is positioned by a couple ring  516 , the lock pin  512  does not drop out of the first U-shaped cut  5061 . If folding the LCD to 90 degrees is desired, the pressure between the protrusive portion  544  and the rotation control unit  506  is overcome only by applying an external force. When the protrusive portion  544  is uncoupled from the first U-shaped cut  5061 , the LCD can be further rotated and the spring  514  is compressed again. 
     In practical application, the size and position of the U-shaped cuts of the invention can be selectively varied to accommodate the rotation angle range. For example, if the rotation angle range of LCD is set up as 10 degrees forward to 30 degrees backward, the first U-shaped cut  5061  is shifted to the associated position. 
     From the above descriptions of the operation of the apparatus for supporting a monitor of the first and second embodiments, it is apparent that the rotation control unit is a key feature of the invention. The rotation angle of the LCD depends on the size of the U-shaped cuts of the rotation control unit. Although the rotation angle range of 2 degrees forward to 25 degrees backward is taken for illustration, the rotation angle of the invention is not limited herein. 
     According to the aforementioned descriptions, the apparatus for supporting a monitor has several advantages. The mechanical apparatus for supporting a monitor of the invention, using a rotation control unit and a tenon or lock pin, has better a position effect than the conventional supporting apparatus. The LCD equipped with the apparatus for supporting a monitor of the invention is not easy to be aged, and the durability thereof is highly increased. The overall size of the apparatus for supporting a monitor of the invention is reduced, so that the space for connecting the LCD and the base is smaller. 
     While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.