Abstract:
A latch is disclosed. The latch has a hook that rotates to engage with a case for a computer. The hook has one side fabricated from a ferrous material. The hook is unlatched by placing a magnet near the ferrous material thereby causing the hook to rotate and disengage with the top case.

Description:
BACKGROUND 
       [0001]    Portable computers typically have a top and bottom case that are joined together to form an enclosure for the internal components. Users may need to open the case to add or remove components, change the battery, or to replace damaged components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1A  is an example two part case for a computer. 
           [0003]      FIG. 1B  is an example hinged two part case for a computer. 
           [0004]      FIG. 2A  is a side view of an example latch  200 . 
           [0005]      FIG. 2B  is a top sectional view of the example latch as seen from AA in  FIG. 2A   
           [0006]      FIG. 3  is a top sectional view of another example latch. 
           [0007]      FIG. 4  is a flow chart for an example method of manufacturing a computer 
       
    
    
     DETAILED DESCRIPTION 
       [0008]      FIG. 1A  is an example two part case for a computer, for example a notebook or portable computer. The two part case has a top case  102  and a bottom case  104  that fit or mate together in a clam shell style. The top case  102  can be installed or removed from the bottom case in a linear fashion as shown by arrows  108 .  FIG. 1B  is another example of a two part case that is joined together with a hinge  106  along one edge. The top case  102  in  FIG. 1B  is opened or closed by rotating the top case  102  about hinge  106 . In both  FIGS. 1A and 1B  the top  102  and bottom  104  cases form an enclosure that can contain internal computer components when the cases are closed or mated together. The internal computer components can comprise a motherboard, memory, hard disk drives, DVD drives, I/O cards and the like. 
         [0009]    Once in the mated position, the top case  102  and the bottom case  104  may be held together by tabs, or a hinge, and one or more latches.  FIG. 2A  is a side view of an example latch  200 . Latch  200  comprises a shaft  210  and a hook  212 . The shaft may be mounted to the inside surface of the bottom case  102 . Hook  212  is mounted on shaft  210  and can rotate about the shaft  210  from a first or “open” position to a second or “latched” position. Hook  212  is shown in the “latched” position in  FIG. 2A .  FIG. 2B  is a top sectional view of latch as seen from AA in  FIG. 2A . Hook  212  has a first part on one side of shaft  210  and a second. part on the other side of shaft  210 . 
         [0010]    The end or tip of the first part of hook  212  is bent. When the hook is in the “latched” position. the end or tip of the first part of hook fits into, or engages with, a hole  214  formed in a side wall of top case  102 . When engaged with the side wall of the top case  102 , the tip of hook  212  holds the top case  102  and the bottom case  104  together. When the hook is rotated about shaft  210  into the “open” position (as shown by the dashed lines in  FIG. 2B ), the end or tip of the first part of hook no longer engages with the hole  214 . Therefore when hook  212  is in the open position the latch  200  allows the top case  102  to be removed from the bottom case  104 . 
         [0011]      FIG. 3  is a top sectional view of another example latch. In this example the side wall of bottom case  104  has a recess  332  that aligns with the hole  214  in the side wall of top case  102  when the two case parts are mated together. When the hook  212  is in the “latched” position the tip of the first part engages with the hole  214  in the side wall of top case  102  and the recess  332  in the side wall of bottom case  104 . Because the end of the hook  212  engages with both walls, there may be less torque applied against the shaft  210  when someone tries to open the top case when the hook is in the latched position. In both examples (shown in  FIGS. 2 and 3 ) the hook  212  is completely enclosed by the top and bottom cases when the cases are mated together. 
         [0012]    The second part of the hook  212  (shown as section  330  in  FIG. 3 ), opposite the bent part of the hook  212 , is fabricated from a ferrous material, for example iron or steel. The two side walls of the case parts are fabricated from a non-ferrous material, for example plastic or aluminum. When a magnet  334  is placed adjacent to the second part  330  of the hook  212  on the outside of the case parts, a magnetic force is created between the magnet  334  and the second part  330  of the hook  212 . The magnetic force causes the hook to rotate into the first or open position, thereby releasing the top case  102  from the bottom case. In one example a mark or target may be located on the outside of the bottom case  336  to show where the magnet should be placed to open the latch. 
         [0013]    A spring may be positioned on latch  200  to move the hook into the second or latched position in the absence of a magnetic force. In some examples the spring may be a coil spring mounted to shaft  210 . The spring force does not oppose the opening force from the top case (i.e. the spring force acts perpendicular to the opening force of the top case). In some examples the tip of the first part of latch  212  may be chamfered to allow the top case  102  to be assembled onto the bottom case  104  without the use of a magnet to hold the hook  212  in the open position. 
         [0014]    The thickness of the side walls of the top and bottom cases, the amount of ferrous material in section  330  of hook  212 , the force of the spring holding the hook  212  in the latched position, the distance between the magnet and section  330 , and the strength of the magnet control the amount of magnetic force between the magnet and section  330 . 
         [0015]    In one example the wall thickness T1 of the bottom case is between 1-1.5 mm (see  FIG. 2A ). The wall thickness T2 of the top case is also between 1 and 1.5 mm. In other examples the wall thickness of the case parts may be in the range between 0.5-3.0 mm. The distance d between section  330  of hook  212  and the inside surface of the top case  102  (see  FIG. 3 ) is based on how far the tip needs to move to disengage from the top and bottom case parts. For example, when the wall thicknesses of the two case parts are 1 mm and the recess  332  is 0.5 mm deep, and a clearance of 0.5 mm between the tip and the top case is desired, the tip would be moved 1 mm (top case wall thickness)+0.5 mm (recess depth)+0.5 mm (clearance)=2 mm between the latched position and the open position. 
         [0016]    Once distance d is determined, the strength of the magnet can be determined. In the example above, the magnet can be brought to within about 4 mm of section  330  of hook  212 . Using this distance, and the amount of ferrous material in section  330 , the strength of magnet  334  can be determined. The magnet does not need to be a magnet with poles. The magnet used can be a permanent magnet, an electro magnet, a ceramic magnet, or the like. Because the latch is opened using a magnet, there are no loose parts that can be lost when the case is opened. In addition, no openings are required in the outer case part which allows for a smooth unbroken look to the case parts. In the examples above, the latch was shown attached to the bottom case part  104 . In other examples the latch may be attached to the top case part  102 . 
         [0017]      FIG. 4  is a flow chart for an example method of manufacturing a computer. At step  442  a first case part and a second case part are formed with side walls fabricated from a non-ferrous material. The first and second case parts form an enclosure when mated together. At step  444  a latch is attached to the first case part. The latch comprises a shaft and a hook rotatably attached to the shaft, where the hook can rotate between and open position and a latched position, the hook having a first side and a second side. Wherein the first side of the hook is engaged with a hole formed in the side wall of the first case when the hook is in the latched position and the first and second cases are mated, and where the first side of the hook is disengaged with the hole when the hook is in the open position. And the second side of the hook formed of a ferrous material and located adjacent to the side wall of the first case, wherein the hook rotates to the open position when a magnet is positioned on an outside of the side wall of the first case, near the second side of the hook.