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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to cover restricting mechanisms and, more particularly, to a cover restricting mechanism for a foldable electronic device such as a mobile telephone, an electronic notebook, and so on.  
         [0003]     2. Discussion of the Related Art  
         [0004]     With the development of the technologies of wireless communication and information processing, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. These electronic devices enable consumers to enjoy the convenience of high technology services anytime and anywhere. Foldable electronic devices are particularly welcome by consumers for their convenience.  
         [0005]     Generally, foldable electronic devices have most of the electronics in one housing, called the body. The other housing, called the cover, normally contains fewer electronic components than the body. Other foldable electronic devices have all the electronics in the body, with the cover containing no electronics. Various types of hinge assemblies are used to join a body and a cover of a foldable electronic device, so that the cover can unfold up from and fold down upon the body. Manufacturers are constantly seeking to reduce the volume, size, and weight of such foldable electronic devices. Also, it is desirable for the hinge assembly coupling the body with the cover to have a long working lifetime.  
         [0006]     A modularized hinge assembly is generally used to hinge together a cover of a foldable electronic device and a body of the foldable electronic device. The hinge assembly typically includes moving parts such as a cam member having a cam surface, a cam follower having a cam follower surface, a spring, a shaft, and a housing. The cam member, the cam follower, and the spring are placed around the shaft and then received in the housing, thereby being held together in a unified structure. The housing is secured to the body, and the cam member engages with the cover. The cam member and the cam follower always contact each other by engagement of the cam and follower surfaces and due to the action of the spring. When opening the cover, the cover is rotated by hand, which makes the cam member rotate along with the cover. At the same time, the cam member urges against the cam follower, making the cam follower move along the shaft and compress the spring. When the cam member rides over a convex portion of the cam follower, the cover is opened to a predetermined angle. Releasing the cover, the cam follower urges against the cam member, under the force of the spring, and makes the cam member continuously rotate, thus making the cover open fully.  
         [0007]     In the above-described hinge assembly, when the cover is opened to a predetermined angle, the cover rotates to a predetermined position. This rotation occurs due to the engaging relationship of the cam follower and the cam member, such engagement being maintained under the force of the spring. However, the abrupt force of the spring of the hinge assembly has a large impact on the cover, which may damage the cover and/or decrease the working lifetime of the cover. Such a negative influence on the operation of the cover would expectedly reduce the working lifetime of the foldable electronic device, overall. In addition, many foldable electronic devices need to be opened to other positions such as 150° or 160° positions. This angle requirement means that the body of the foldable electronic device itself needs to be specially designed in order to limit the maximum opening angle of the cover. This designing takes up valuable “real estate” on the body, increases the complexity of the manufacture of the body, and increases the overall volume and weight of the mobile phone. Furthermore, each time the cover is opened, it impacts the body. The body is liable to become worn or damaged due to such impact, thereby shortening the working lifetime of the mobile phone.  
         [0008]     What is needed, therefore is to provide a cover restricting mechanism that overcomes the above-described problems.  
       SUMMARY OF THE INVENTION  
       [0009]     A cover restricting mechanism is adapted/configured for use in a foldable electronic device. The foldable electronic device includes a cover and the cover restricting mechanism. The cover restricting mechanism includes a follower, a housing, and a restricting mechanism. The follower is provided at one end of the cover. The housing has a cavity defining an inner surface of the housing. The restricting mechanism is provided at and against the inner surface of the housing. The restricting mechanism is adapted/configured for rotatably receiving the follower therein. The restricting mechanism is particularly configured such that, when the cover is rotated to an open position, the follower rotates with the cover, and the restricting mechanism retards or restricts the follower and, thus, the cover.  
         [0010]     When the cover restricting mechanism is installed in the foldable electronic device, opening and closing the cover is easy. When the user manually rotates the cover to a predetermined angle toward an open position, the restricting mechanism can reduce impact of the cover as a result of the abrupt force generated by a spring of a hinge assembly installed in the foldable electronic device. Also, the restricting mechanism can reduce the vibration/shaking of the cover. In addition, the structure of the cover restricting mechanism is simple and thus should not increase the volume of the foldable electronic device much at all, if any.  
         [0011]     Other advantages and novel features of the preferred embodiment will become more apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     Many aspects of the present cover restricting mechanism can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, the emphasis instead being placed upon clearly illustrating the principles of the present cover restricting mechanism and its potential applications. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0013]      FIG. 1  is an exploded, isometric view of the cover restricting mechanism, incorporated in a foldable electronic device, in accordance with a preferred embodiment;  
         [0014]      FIG. 2  is an exploded, enlarged view of a restricting mechanism of the cover restricting mechanism of  FIG. 1 ;  
         [0015]      FIG. 3  is similar to  FIG. 2  but viewed from another aspect;  
         [0016]      FIG. 4  is an assembled view of the restricting mechanism of the cover restricting mechanism of  FIG. 3 ;  
         [0017]      FIG. 5  is a cross-sectional view of a housing of the cover restricting mechanism along line V-V of  FIG. 1 ;  
         [0018]      FIG. 6  is an isometric view of a cover incorporating the cover restricting mechanism;  
         [0019]      FIG. 7  is a partial cross-sectional view of the cover restricting mechanism, corresponding to a partly open position of the foldable electronic device; and  
         [0020]      FIG. 8  is similar to  FIG. 7 , but showing the cover restricting mechanism corresponding to an open position of the foldable electronic device. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]     Referring now to the drawings,  FIG. 1  shows a cover restricting mechanism  8  according to a preferred embodiment of the present mechanism. The cover restricting mechanism  8  is adapted for use in a foldable electronic device  9 .  
         [0022]     The foldable electronic device  9  includes a body (not shown), a cover  10 , a housing  20 , and a hinge assembly (not shown). The housing  20  is formed at or otherwise attached to one end of the body. The hinge assembly is contained in the housing  20  and is used to hinge the body and the cover  10  together. The hinge assembly can be any kind of hinge assembly, the hinge assembly generally, for example, including a shaft, a cover driven member, a body driven member, and a spring.  
         [0023]     The cover restricting mechanism  8  includes the housing  20 , a follower  31 , a restricting mechanism  32 , and a positioning portion  33 , also referring to  FIG. 5 . The follower  31  is provided at one end of the cover  10 . The restricting mechanism  32  and the positioning portion  33  are provided in the housing  20 .  
         [0024]     The cover  10  includes a first support portion  11  and a second support portion  12 , each of which is formed at a same end of the cover  10  and at sides opposite to each other. A first column portion  110  and a barrel portion  120  respectively extend from the first support portion  11  and the second support portion  12 , and such portions  110 ,  120  face one another. The barrel portion  120  is substantially in the form of a hollow cylinder. The follower  31  extends from a projecting end of the first column portion  110  and includes a second column portion  311  and a follower projection  312 . The second column portion  311  joins the first column portion  110  and is arranged coaxially with the first column portion  110 . The follower projection  312  is provided on an outer (i.e., peripheral) surface of the second column portion  311 .  
         [0025]     The housing  20  is substantially in the form of a hollow quarter-cylinder, and the housing has a center cavity  21  and a channel  210 . The center cavity  21  is defined through a center portion of the housing  20  along a center axis thereof The channel  210  is formed in a wall of the housing  20  along a center axis thereof, and this channel  210  communicates with the center cavity  21  of the housing  20 . The surfaces associated with the center cavity  21  and the channel  210  together effectively define the inner surface of the housing  20 , as a whole. Referring also to  FIG. 5 , the positioning portion  33 , which is integral with the inner surface of the housing  20  in the center cavity  21  in the illustrated embodiment, includes an annular protrusion or projection  331  and two receiving holes or slots  332 . The annular protrusion  331  extends from an inner surface of the housing  20  in a radial direction. The receiving holes  332  are defined through the annular protrusion  331  along an axial direction thereof The receiving holes  332  communicate with the center cavity  21  of the housing  20 . It is to be understood that positioning portion  33  could instead be manufactured as a separate unit, made of one or more pieces, and be configured for insertion into the center cavity  21 , and such a unit would be within the scope of the present foldable electronic device  9 .  
         [0026]     Also referring to  FIGS. 2-4 , the restricting mechanism  32  includes a receiving element  321  and a damping element  322 . The receiving element  321  is substantially a circular wall and defines a first arc inner face  3211  and a second arc inner face  3212  through a center thereof along a center axis. The first arc inner face  3211  and the second arc inner face  3212  are opposite to each other and join with each other to help define an arc-faced through hole  3217 . A diameter of the first arc inner face  3211  is equal to a diameter of the second column portion  311 . A semi-diameter of the second arc inner face  3212  is a sum of a semi-diameter of the second column portion  311  and a height of the follower projection  312 . The receiving element  321  further includes a pair of stop faces  3218 , extending respectively from opposing ends of the first arc inner face  3211  toward the second arc inner face  3212 . Such stop faces  3218  act as stop limits for the angular motion range of the follower projection  312  and, thus, the cover  10 . The receiving element  321  further has a wall opening  3213 , a first receiving channel  3214 , and a second receiving channel  3215  defined therein. The arc-faced through hole  3217 , the wall opening  3213 , the first receiving channel  3214 , and the second receiving channel  3215  communicate with one another. The first receiving channel  3214  and the second receiving channel  3215  are opposite to each other. Two protrusions  3216  are provided at one end of the receiving element  321 . The two protrusions  3216  are engaged with the receiving holes  332  of the positioning portion  33 .  
         [0027]     The damping element  322  is shaped for reception in the wall opening  3213 , the first receiving channel  3214 , and the second receiving channel  3215  and is made of elastic rubber or another suitably elastic material. The damping element  322  includes a central damping section  3224 , a first arm  3222 , and a second arm  3223 . The central damping section  3224  is a generally convex-concave member and includes a convex arc protrusion  3221  arranged so as to face toward the arc-faced through hole  3217 . The shape, arrangement, and material make-up of the central damping section  3224  allow it act like a spring and thereby absorb shock/force. As such, the damping element  321  helps promote a long working lifetime for the restricting element  32 . The convex arc protrusion  3221 , upon assembly, is configured to interact with the follower projection  312  during opening of the cover  10 . Specifically, the convex arc protrusion  3221  absorbs a portion of the force placed upon the follower projection  312  by the hinge assembly during opening, thus slowing its travel and, accordingly, that of the cover  10 . The first arm  3222  and the second arm  3223  extend from two opposite sides of the central damping section  3224 , respectively. The first arm  3222  is engaged with the first receiving channel  3214  of the receiving element  321 . The second arm  3223  is engaged with the second receiving channel  3215  of the receiving element  321 . The central damping section  3224  is engaged with the opening  3213  of the receiving element  321 .  
         [0028]     In assembly, the damping element  322  of the restricting mechanism  32  is assembled with the receiving element  321 . The first arm  3222 , central damping section  3224 , and the second arm  3223  are engaged, respectively, with the first receiving channel  3214 , the opening  3213 , and the second receiving channel  3215 . The assembled restricting mechanism  32  is inserted into the center cavity  21  of the housing  20  with the protrusions  3216  of the restricting mechanism  32  respectively engaging with the receiving holes  332  of the positioning portion  33 , which extends from an inner surface of the housing  20  in a radial direction. The hinge assembly is inserted into the center cavity  21  of the housing  20 . The housing  20  is mounted to the end of the cover  10 . The barrel portion  120  of the cover  10  is received in one end of the housing  20 , and the column portion  110  of the cover  10  is received in an opposite end of the housing  20 , as represented in  FIG. 6 . Wires may connect circuits in the cover  10  and circuits in the body by means of the channel  210  of the housing  20 .  
         [0029]     Referring to  FIGS. 7-8 , in use, when a user wants to open the cover  10 , he/she may manually rotate the cover  10  up to an open position. The follower projection  312  rotates with the cover  10 . When the cover  10  is opened to a predetermined angle, the cover  10  is opened automatically under the force of the spring of the hinge assembly because of the release of the spring. When the follower projection  312  contacts the arc protrusion  3221  of the restricting mechanism  32 , the arc protrusion  3221  is compressed and produces a resilient force. The moving rate of the cover  10  is thereby retarded/slowed down by the resilient force produced by the arc protrusion  3221 . Then, the cover  10  continuously rotates to a fully open position at a very low rate, thus lowering the impact experienced by the cover  10  upon reaching the full-open position.  
         [0030]     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Summary:
A cover restricting mechanism ( 8 ) is adapted for use in a foldable electronic device ( 9 ). The foldable electronic device includes a cover ( 10 ). The cover restricting mechanism includes a follower ( 31 ), a housing ( 20 ), and a restricting mechanism ( 32 ). The follower is provided at one end of the cover. The housing has a cavity ( 21 ). The restricting mechanism is provided in the cavity of the housing, and when the cover is rotated to an open position, the follower rotates with the cover, and the restricting mechanism retards/slows the progress of the follower, thereby helping the cover to come more gently to a full, open position.