Abstract:
This invention provides an anti-vibration method for rotating disks and its apparatus for color wheel modules. It effectively eliminates vibration of a rotating disk due to unbalance. The method involves filling a curable fluid in a holder of the rotating disk. When the disk rotates, the curable fluid flows to balance the disk, and the fluid is then hardened at this balance position. As a result, it can effectively eliminate vibration of a rotating disk, such as a color wheel module.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an anti-vibration method for rotating disks and its apparatus adopted for use on rotating disks such as color wheel modules, and more particularly, to a method and apparatus that employs curable fluid to eliminate vibration generated by a rotating disk.  
         BACKGROUND OF THE INVENTION  
         [0002]    In theory, a rotating disk may rotate about the rotational spindle in a steady and balanced manner. However, in practice, due to inherent manufacturing defects or assembly problems, the substance of the rotating disk does not evenly distribute. As a result, vibration occurs when the rotating disk rotates. Although the vibration amplitude might not be significant in some circumstances, with precise optical instruments it becomes a critical factor whether the required precision level can be achieved.  
           [0003]    Take the color wheel module for example. Color wheel modules have been widely used in picture display devices. The color wheel consists of a plurality of colored filter films bonding together. Its rotation modulates the color of the incident light to provide light beams with the sequential color changed at a rapid frequency so that the picture display device can produce the required picture formation. As the color wheel switches the color of the incident light through rotation, balance becomes an important issue.  
           [0004]    Conventional balance methods mostly try to determine the unbalanced location through actually driving a disk  11 . As shown in FIG. 1A, the disk  11  is driven to rotate by a motor  12 . Because the unbalance substance M of the disk generates a centrifugal force during rotating, the centrifugal force incurs vibration. A sensor such as an accelerometer may be used to detect the amplitude and phase angle of the vibration. Based on the vibration amplitude and phase angle, the unbalance substance M and its phase angle θ may be determined. Moreover, in order to avoid interference caused by the mounting plane such as the table top which the disk  11  is driven, the disk  11  and the motor  12  may be mounted onto a suspending surface  13  supported by springs  14 .  
           [0005]    Refer to FIG. 1B for calculating the unbalance condition. When the unbalance substance M and the phase angle of a disk  11  are known, there are two common approaches to remedy the problem, i.e. adding or removing the corresponding substance. Manufacturers may choose to add a corresponding substance on a location 180 degrees against the unbalance substance M to eliminate the vibration. It is also possible to remove a corresponding substance on the location of the unbalance substance M to eliminate the vibration. However, in practice, the location and amount of the unbalance substance M cannot be calculated as accurately as desired. In most circumstances, only proximate values are obtained. Then trial and error approaches are taken to perform correction. For instance, a drill out method may be taken to remove the substance. When the unbalance substance M of the disk  11  is obtained, a small hole may be drilled on the location where the unbalance substance M is positioned to remove a selected amount of substance. Then a test run is taken. If the result is not satisfactory, another small hole is drilled. In the event that too many holes are drilled on one side, a small hole is drilled on the diagonal side. The process is repeatedly performed until the disk  11  is balanced. Such a balance method is inefficient. Even the final balance attained is not totally desirable. It can only reach a balance within the range of tolerances of measurement and calculation.  
         SUMMARY OF THE INVENTION  
         [0006]    The primary object of the invention is to resolve the foregoing disadvantages. The present invention provides an anti-vibration method for rotating disks and its apparatus for eliminating vibration of color wheel modules and rotating disks so that they may be freed from vibration caused by unbalance during a rotation process.  
           [0007]    The anti-vibration method for rotating disks and apparatus of the present invention includes a holder formed on a rotating disk to contain curable fluid. When the rotating disk rotates, the fluid will automatically flow to and distribute on balanced positions due to the vibration force. Then the fluid is curdled and solidified. Thus, balance can be reached for the rotating disk. The flowage of the fluid is done due to the vibration so that the fluid will keep floating until the vibration is gone. Such a method and structure is not only easier to implement, it also can attain more precise balance.  
           [0008]    The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1A is a schematic view of a conventional structure for measuring unbalance conditions of a rotating disk.  
         [0010]    [0010]FIG. 1B is a schematic view of a conventional rotating disk in an unbalance condition.  
         [0011]    [0011]FIGS. 2A, 2B and  2 C are schematic views of the invention showing the automatic balance principle.  
         [0012]    FIGS.  3 A- 3 C are schematic views of the invention, showing balance processes.  
         [0013]    FIGS.  4 A- 4 D are schematic views of the invention.  
         [0014]    [0014]FIG. 5 is a schematic view of the invention, showing a balance structure.  
         [0015]    [0015]FIGS. 6A and 6B are schematic views of an application of the invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    Refer to FIGS. 2A and 2B for the anti-vibration method of rotating disks adopted for use on color wheel modules and rotating disks for eliminating vibration. As shown in the drawings, there is a container  21  with an unbalance substance M. The container  21  further holds a plurality of steel balls  22 . When the container  21  rotates at a selected angular speed ω (referring to FIG. 2C), the unbalance substance M incurs a vibration displacement e due to the centrifugal force. The vibration displacement e generates a force Fe (Fe=meω 2  where m is the substance of the steel balls) on the steel balls  22 . The component force Ft (Ft=Fe* cos (α), where α is the included angle against the radial direction) of the force Fe in the tangential direction moves the steel balls  22  along the perimeter direction opposite to the unbalance substance M until reaching a balance condition. Due to the friction between the steel balls  22  and the container  21 , it is difficult for the steel balls  22  to reach a completed balance condition. As fluid does not have friction problem, the curable fluid can replace the steel balls  22  to attain a completed balance condition.  
         [0017]    Refer to FIG. 3A for an embodiment of the invention adopting the principle set forth above. There is a rotating disk  31  with a bowl  32  located thereon to form a holder for containing curable fluid  33 . In the event that an unbalance substance M is located on one side of the rotating disk  31 , according to the principle set forth above, the fluid  33  is subject to the vibration force and flows along the perimeter direction to the other side, but will be held in the holder due to the constraint of the side wall of the holder (as shown in FIG. 3B). Refer to FIG. 4A for an example. The unbalance substance M is located on the right side, so the fluid  33  finally accumulates on the left side of the bowl  32  (as shown in FIG. 3C). In an ideal condition, all of the fluid is totally accumulated on the left side (as shown in FIG. 4A). However due to viscosity and surface tension and centrifugal force, the actual fluid distribution is like that shown in FIG. 4C. In such a condition, the fluid substance accumulated on the left side offsets the unbalance substance M on the right side, the rotating disk  31  reaches a balance condition, and the vibration caused by unbalance can be prevented. Once the balance condition is attained, the fluid  33  is curdled and solidified. The distributed state may be fixed to maintain a permanent balance condition.  
         [0018]    Furthermore, the application of FIG. 2A to FIG. 3D can be combined because it run under same principle. The steel balls can be put into the above-mentioned fluid to enhance the capability of reducing the mass unbalance.  
         [0019]    Compared with the conventional methods, using fluid  33  to achieve balance distribution not only saves the time of the trial and error process, but the balance condition is also more precise. The curable fluid  33  may be selected from photosensitive curable fluid (such as UV gel), thermal sensitive curable fluid or double agent curable gel. The curing of the fluid  33  may be done by providing photo energy, thermal energy, catalysts or the like. It is to be noted that the curable fluids and curing methods mentioned above are only to serve as examples; other types of curable fluid may also be selected as desired.  
         [0020]    [0020]FIG. 4A illustrates an embodiment of the holder that is formed by mounting a bowl  32  onto a rotating disk  31 . The mounting process can be accomplished by adhering, screwing, coupling, latching or other fastening means known in the prior art. In order to prevent the fluid  33  from spilling out during rotating, an extended flange may be formed on the top edge of the side wall of the bowl  32 . Of course an annular element  34  may also be used (as shown in FIG. 4B) to mount onto the rotating disk  31  to form the holder on the rotating disk  31  to contain the fluid  33 . On the other hand, when the amount of the fluid  33  is not much, or the bowl  36  and the annular element  35  have a higher side wall, the extended flange may be dispensed with (referring to FIGS. 4C and 4D).  
         [0021]    For performing balance in practical situations, the rotating disk  31  may be mounted onto a spindle  42  of a motor  41  and driven to rotate. Similarly, in order to prevent interference or inaccurate measuring, a suspending board  43  supported by springs  44  may be used to anchor the whole structure as shown in FIG. 5.  
         [0022]    Refer to FIGS. 6A and 6B for the invention adopted on a color wheel module. The color wheel module consists of a motor  54 , a spindle  541 , a holder  52  and a color wheel  51 . The motor  54  drives the spindle  541  to rotate. The holder  52  is formed on the inner peripheral rim of the color wheel  51  and is coaxial with the color wheel  51 . Moreover, the holder  52  and the color wheel  51  are coupled together and are tightly mounted onto the spindle  541  and driven by the motor  54  for rotating.  
         [0023]    The holder  52  is bonded to the inner peripheral rim of the color wheel  51 . The bonding method may be direct adhesion or the like. The holder  52  may be formed in any one of the embodiments set forth above (bowl, annular element, etc.) to contain the curable fluid  33 . In addition, the color wheel  51  consists of a plurality of transparent color filter films  511  to modulate and change the color of the light beams passing through. The color filter films  511  mostly include red, green, blue and white colors. They are respectively formed in a fan shape to couple together to form the circular color wheel  51 .  
         [0024]    Once the holder  52  is bonded to the color wheel  51 , balance may be performed independently. Balance may be achieved by the method set forth above, and by means of the apparatus shown in FIG. 5. After balance is attained, the holder  52  is mounted onto the spindle  541 , which is driven by the motor  54  to modulate the color of the light beams alternately. On the other hand, it is also allowable to mount the holder  52  and the color wheel  51  on the spindle  541 , then perform balance and curing. This may be done because fluid curing does not affect the original precision after balance is achieved.  
         [0025]    In summary, the anti-vibration method for rotating disks and its apparatus for color wheels and rotating disks of the invention employs fluid to reach balance positions and distribute under high speed rotation, then uses the curing characteristics to solidify the fluid. Thus balance is easier to achieve and more precise.  
         [0026]    While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.