the lower arm muscles contract and relax , together with the mass of the hand , forming a vibrating system with low damping . in effect , the hand mass and the arm muscles are analogous to a simple spring mass vibrating system , in which body chemicals supply muscle energy and the nerves activate muscles . if the spring is shortened while maintaining the same amount of vibratory energy , the amplitude of oscillation is reduced with a higher resonant frequency . the spring mass resonant frequency with low damping is roughly proportional to the square root of the spring tension per unit length . therefore , by compressing a selective group of muscles at a location that is about one quarter of full muscle length , tremor vibration rate is roughly doubled and vibration amplitude is decreased substantially . chemical energy provided to the shortened portion of the muscle is less than that of the entire muscle which further aids in reducing the tremor . detrimental nerve - to - muscle response that reinforces the vibration may also be reduced at a higher resonant frequency . the present invention provides a mechanical device configured to compress a selective group of muscles at a location of an arm in order to reduce the tremor vibration amplitude by shortening the segment of the muscles that contract and relax . the mechanical device can be made contact to the location of the inner arm by a band or another retaining mechanism . fig1 shows a tremor reduction device , according to an embodiment of the present invention , held onto the arm by a band . fig2 shows an isometric view of the tremor reduction device . as shown in fig1 and 2 , tremor reduction device 100 has a case 101 , which is attached to a band 200 . tremor reduction device 100 is positioned at a location of the inner arm for selectively applying pressure to the muscles and tendons on the arm . for example , tremor reduction device 100 can be positioned about 2 - 5 inches from the hand - wrist line . optionally , a controlling device 300 is operatively connected to tremor reduction device 100 for providing automatic tremor control , for example . as shown in fig2 , tremor reduction device 100 has a sliding slot 110 , in which a control rod 120 can be manually moved to different positions to change the pressure applied to the inner arm . for example , the pressure can be set to be low ( l ), medium ( m ) or high ( h ) as indicated by indicators 130 . control rod 120 is used to raise or release a flap that contacts with the arm at a pressure applying point ( see fig5 ). the control rod positions can be reset and released manually . the case 101 of tremor reduction device 100 has two slots 102 to be engaged with band 200 by bars 104 . the shape of tremor reduction device 100 can be elliptical with rounded edges for greater comfort , for example . the back side of tremor control device 100 can also be contoured both for comfort and to counter the flap force against the case 101 of tremor reduction device 100 . case 101 can have an area approximately 2 × 2 inches and a depth about 6 inch . band 200 can be made of elastic , plastic , leather or other flexible materials . the two ends of the band that wraps around the arm can be joined by one or more fabric hook - and - loop fasteners , buckles , snaps or other securing means . fig3 shows a front view of the tremor reduction device . as shown in fig3 , tremor reduction device 100 has an inner channel 140 to allow movable rod 150 to move laterally and bi - directionally as indicated by arrow 148 . movable rod 150 can be moved by control rod 120 along sliding slot 110 . as can be seen in fig6 , movable rod 150 can also be moved bi - directionally by a motor 332 ( or other movement device ) via a linear drive mechanism 336 . fig4 shows a back view of the tremor reduction device . fig5 is a cross sectional view of the tremor reduction device . as shown in fig4 and 5 , tremor reduction device 100 has a flap opening 166 to accommodate a flap 160 and to allow one end of flap 160 to move in and out of the opening . flap 160 has a flap portion 162 that contacts with the inner arm for applying pressure to the muscles and tendons around the contacting point . as shown in fig5 , flap 160 is pivotally mounted at a pivot rod 164 . flap 160 has a rounded head pin 170 arranged to be in contact movable rod 150 . as shown in fig6 , movable rod 150 has a tapered section 153 on side 152 . on side 154 , movable rod 150 has a dent 156 to be engaged with control rod 120 ( see fig3 and 5 ). depending on the positions of rounded head pin 170 in the tapered section 153 , flap portion 162 can be closer to or further from surface 152 of movable rod 150 . as control rod 120 is moved to different positions in sliding slot 110 ( see fig3 ), the flap angle θ can be increased or decreased . as the flap angle is increased from a small angle , such as 0 degree , to a larger angle , flap portion 162 compresses selective muscles and tendons and applies pressure to the flesh toward the arm and , more significantly , against the radial bone . the flap can be made of metal , plastic or other sturdy materials while the flap portion that contacts with the arm can be made of rubber or other compressible materials . fig4 and 5 also show the mounting slots 102 and bars 104 for attaching case 101 to a band ( fig2 ). the flap pressure required to compress muscles and tendons against the radial bone is less than it is required to compress the flesh alone . the advantages of the reduced flap pressure are greater comfort and the minimal disturbance to the blood vessels and nerves around the pressure applying point . in addition , by choosing the flap positions , the compression on the muscles and tendons that control finger movement in normal activities can be avoided or minimized . the dimensions of the flap can range from ¾ to 4 inches parallel to the arm and ½ to 5 / 4 inches across the arm , for example . a larger flap area may reduce pressure and could be more effective in clamping muscles and tendons . flaps with varying flexibility and different outlined contours can be interchanged in order to accommodate different users . for example , a smaller arm or wrist may require a smaller flap portion . flap changing can be done by removing the pivot rod 164 ( see fig4 and 5 ). in an embodiment of the present invention , the tremor reduction device as illustrated in fig1 to fig6 can be used as a stand alone device to reduce tremors in limb and extremity . in another embodiment of the present invention , the tremor reduction device can be used in conjunction with an automatic tremor detector and controller , such as controlling device 300 as depicted in fig1 controlling device 300 may have various functions as shown in fig7 . as shown in fig7 , controlling device 300 may comprise a vibration sensor 310 , a signal processor 320 , a driving circuit 330 with a motor 332 , a linear drive 334 , a linear drive mechanism 336 , a battery or external power source 370 , a switch 360 , a manual set 340 and a timer 350 . for example , vibration sensor 310 can be used to sense the tremors of the arm and provides a sense signal 312 to signal processor 320 . signal processor 320 may comprise an amplifier , a signal filtering circuit and a demodulator , for example , for processing the sense signal and providing a drive signal to driving circuit 330 . driving circuit 330 may comprise a signal averager , a comparator and a motor driver , for example . the motor driver is arranged to cause motor 332 to turn . through linear drive 334 , the rotational motion of motor 332 is translated into a linear motion in order to move movable rod 150 bi - directionally via linear drive mechanism 336 . as rounded head pin 170 interacts with tapered section 153 on movable rod 150 driven by motor 332 , one end of flap 160 is moved in and out of flap opening 166 and flap angle e is changed accordingly ( see fig5 ). as such , controlling device 300 may be used to adjust the pressing force applied by flap portion 162 based on the tremor sensing by vibration sensor 310 . vibration sensor 310 can be a coil disposed in relationship to a magnet , for example . as arm tremors vibrate the magnet relative to the coil , induced current in the coil can be used as a sense signal . linear drive 334 , which can be overridden by manual control , may have a thread screw to translate the rotational motion to the linear motion . through linear drive mechanism 334 , linear drive 334 moves movable rod 150 as a function of the comparator output , based on signals from manual set 340 and the signal averager in driving circuit 330 , for example . an additional very long - term average signal may augment the manual setting . furthermore , a timer 350 may be used to control the time duration and / or the force of the pressure . for example , timer 350 can be programmed to reduce the pressure gradually over a period of time , but the user may reset to increase the pressure or disable the timer if so desired . timer 350 , which can be mechanical or electronic , can be activated by the sense signal , for example . the manual switch 360 can be used by a user to turn the controlling device 300 on or off . as can be seen in fig5 and 6 , flap portion 162 , along with one end of flap 160 , is pushed outward from flap opening 166 by control rod 120 via rounded head pin 170 , which is made contact tapered section 153 of movable rod 150 . when the tremor reduction device is in use , flap 160 is pushed back by the flesh on the arm . nevertheless , flap 160 is returned to flap opening 166 by a leaf spring , according to an embodiment of the present invention , it should be understood that control rod 120 in sliding slot 110 provides limit stops for movable rod 150 . when a limit stop is reached , the current that drives motor 332 would rise sharply . this increase in the motor current can be used for rod control , eliminating the use of limit switches and the wiring between controlling device 300 and tremor reduction device 100 , for example . in general , motor 332 is only used for positioning flap 160 . thus , a sleeper circuit ( not shown ) can be used to prolong the life of battery 370 . in one embodiment of the present invention , a memory device 380 is used to store data relating to tremors and pressures for analysis purposes , for example . in summary , the present invention provides a tremor reduction device having a flap arranged to contact a part of the human body , such as an arm for applying pressure to the muscles and / or tendons around the part of the human body . the tremor reduction device has a movable rod with a tapered section for varying the pressure applied by the flap to the part of the human body . the movable rod can be moved along a channel in the tremor reduction device by a manual control rod to various locations in a sliding slot for adjusting the pressure . in an embodiment of the present invention , the tremor reduction device is used in conjunction with a controlling device having a movement mechanism arranged to move the movable rod for pressure adjustment . the controlling device has a vibration sensor to sense tremors and to send a sense signal to a signal processor . the signal processor provides a driving signal to a driving circuit to turn on a motor . through a linear drive , the motor moves the movable rode bi - directionally . thus , although the present invention has been described with respect to one or more embodiments thereof , it will be understood by those skilled in the art that the foregoing and various other changes , omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention .