reference will now be made in detail to the preferred embodiments of the invention , examples of which are illustrated in the accompanying drawings . while the invention will be described in conjunction with the preferred embodiments , it will be understood that they are not intended to limit the invention to these embodiments . on the contrary , the invention is intended to cover alternatives , modifications and equivalents , which may be included within the spirit and scope of the invention as defined by the appended claims . furthermore , in the following detailed description of the present invention , numerous specific details are set forth in order to provide a thorough understanding of the present invention . however , it will be obvious to one of ordinary skill in the art that the present invention may be practiced without these specific details . in other instances , well - known methods , procedures , components , and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention . one embodiment of the invention is now described with reference to fig1 to 3 . fig1 shows one embodiment of a patient lift 100 . the patient lift 100 includes a base 101 having a front side and a back side . the base 101 is mounted on a first wheel 101 f 1 , a second wheel 101 f 2 ( not seen in fig1 ; please refer to fig3 ), a third wheel 103 b 1 , and a fourth wheel 103 b 2 ( not seen in fig1 ; see fig3 ). in one embodiment , third wheel 103 b 1 is mechanically connected to the backside of base 101 and electrically connected to a first motor 311 ( not shown in fig1 ; please see fig3 ) whereas fourth wheel 103 b 2 is connected to a second motor 312 . in the embodiment shown in fig1 , first wheel 101 f 1 and second wheel 101 f 2 are caster wheels . they are configured to swivel and change directions as base 101 is moving . continuing with fig1 , a first extendable leg 105 a and a second extendable leg 105 b are mechanically connected to base 101 . first extendable leg 105 a and said second extendable leg 105 b configured to extend or withdraw from the front side of base 101 . a third motor 313 ( not shown in fig1 but can be seen in fig3 ) is mechanically connected to first extendable leg 105 a and second extendable leg 105 b via a glider 315 and a spring 316 ( please see fig3 ) in order to cause first extendable leg 105 a and second extendable leg 105 b extend outward or withdraw from the front side of base 101 through openings as shown in fig1 . in addition , a fifth wheel 104 pf 1 is mechanically connected to first extendable leg 105 a and a sixth wheel 104 pf 2 is mechanically connected to second extendable leg 105 b respectively . in one embodiment , fifth wheel 104 pf 1 and sixth wheel 104 pf 2 are caster wheels similar to first wheel 101 f 1 and second wheel 101 f 2 . referring again to fig1 , a first mast 131 and a second mast 132 are mechanically connected to the back side of base 101 . in one embodiment , the lengths of first mast 131 and second mast 131 are designed to be adjusted so that patient lift 100 can be folded . on top of first mast 131 and second mass 132 , a lever 133 is extended forward toward the front side of base 101 . there , a three - prong hanger having a first prong 152 , a second prong 153 , and a third prong 154 mechanically connected to lever 133 . a rotator 155 interconnects lever 133 and three - prong hanger 152 - 154 so that three - prong hanger 152 - 154 can rotate freely in clockwise and counter - clockwise around a vertical axis . rotator 155 is designed so that a medical assistant can help the patient to face in a correct direction , especially when the patient needs to sit down a chair or a toilet bowl . a fourth motor 151 is connected to rotator and operable to cause rotator 155 to rotate . continuing with fig1 , a first cable 141 , a second cable 142 , and a third cable 143 are connected to each prong of said three - prong hanger 152 - 154 respectively . in one embodiment , first cable 141 , second cable 142 configured to operate simultaneously and third cable 143 are configured to extend or withdraw independently of first cable 141 and second cable 142 . a sling assembly 201 ( not shown in fig1 , please refer to fig2 ) having three different holes are configured to connect to first cable 141 , second cable 142 , and third cable 143 . in one embodiment , said third cable 143 is connected to sling assembly 201 at a location between the patient &# 39 ; s two legs , to first cable 141 at the patient &# 39 ; s left shoulder , and to second cable 142 at the patient &# 39 ; s right shoulder . next , a foldable chair 120 is mechanically connected to first mast 131 and second mast 133 . in one embodiment , foldable chair 120 has a support portion 121 configured to support a patient , and a back portion 122 . a left hand rest 123 and a right hand rest 124 are connected to support portion 121 . continuing again with fig1 , a removable fifth motor 106 is mechanically connected between first mast 131 and base 101 . in one embodiment , one end of removable fifth motor 106 is fixedly connected to first mast 131 and support portion 121 of foldable chair 120 . the distal end of removable fifth motor 106 can be removed so that patient lift 100 can be folded up . next , a first pulley 161 is mechanically coupled to first cable 141 and second cable 142 . a sixth motor 181 is mechanically connected to first pulley 161 . sixth motor 181 is designed to control first cable 141 and second cable 142 simultaneously . on the other hand , second pulley 162 houses to third cable 143 . a seventh motor 182 is mechanically connected to second pulley 162 , operable to control said third cable 143 . still referring to fig1 , a handle 110 connected to the rear end of base 101 . on top of handle 110 , a control panel 111 is designed to control the operations of first motor 311 , second motor 312 , third motor 313 , fourth motor 151 , fifth motor 106 , sixth motor 181 , and seventh motor 182 . finally , a switch box 170 is coupled to second wheel 103 b 1 and fourth wheel 103 b 2 . switch box 170 is configured to decouple third wheel 103 b 1 and fourth wheel 103 b 2 from first motor 311 and second motor 312 so that patient lift 100 can be pushed by the medical assistant . in one embodiment , base 101 has a width of 0 . 75 meters , a maximum length when first extendable leg 105 a and second extendable leg 105 b are fully extended is 1 . 6 meters . base 101 has a minimum length of 1 . 2 meters when first extendable leg 105 a and second extendable leg 105 b are fully withdrawn . the height of base 101 including first mast 131 and second mast 132 is 2 . 25 meters calculated for average human heights between 1 . 7 meters to 1 . 9 meters . now referring to fig2 , patient lift 100 is controlled by control panel 111 to lean forward to pick up a patient . the detailed operation of control panel 111 and patient lift 100 will be discussed later . fig2 also illustrates mast assembly 201 on which a patient is lifted and transported to either foldable chair 120 or to a nearby location . next referring to fig3 , fig3 shows the view of patient lift 100 from the bottom perspective . from this view , first motor 311 and second motor 312 are shown . furthermore , slider 315 and spring to extend or withdraw first extendable leg 105 a and second extendable leg 105 b can also be illustrated . now referring to fig4 , a method 400 for operating patient lift 100 described above is illustrated . basically , control panel 111 has a micro - controller ( not shown ) programmed to control first motor 311 , second motor 312 , third motor 313 , fourth motor 151 , fifth motor 106 , sixth motor 181 , and seventh motor 182 in accordance with predetermined situations when lifting a patient . at step 401 , lift device 100 is reset to its initial position . that is a straight up position perpendicular to the ground . more specifically , if the x - z surface is parallel to the ground , at the reset position , patient lift 100 is coincide to the y - axis as illustrated in fig1 . step 401 is performed by releasing fifth motor 106 so as it pushes first mast 131 and second mast 132 to a vertical direction perpendicular to the ground . then at step 402 , patient lift 100 is moved to where a patient in need of transport . step 402 is realized by using control panel 111 to move forward , backward , turn left , turn right to the patient &# 39 ; s location . at step 403 , a user or a medical assistant selects at least one command buttons on control panel 111 . at step 404 , if a completion button is entered , the command selected at step 403 is final and micro - controller or control panel perform steps programmed in that command . otherwise , micro - controller waits for another command button to be pressed . in other words , according to the present invention , a command button is only performed when it receives the completion command . next , at step 405 , a second command is selected . at step 406 , after the completion command is received , steps pre - programmed in one or two commands are performed . at step 407 , patient lift 100 is bent down to receive a patient . this step is carried out by fifth motor 106 reduces its length , causing first mast 131 and second mast 132 to lean forward . at the same time , foldable chair 120 is folded up . this step 407 is illustrated in fig2 . next , at step 408 , first extendable leg 105 a and second extendable leg 105 b are pushed forward by third motor 313 so as patient lift 100 will not fall forward when lifting up a patient . at step 409 , a user or medical assistant uses first cable 141 , second cable 142 , and third cable 143 to connect to sling assembly 201 . more particularly , first cable 141 and second cable 142 are used on the patient &# 39 ; s shoulder . third cable 143 is used to connect to sling assembly 201 in the area between patient &# 39 ; s legs . at step 410 , micro - controller on control panel 111 controls first cable 141 , second cable 142 , and third cable 143 accordingly to each situation specified by selected commands described in step 403 to step 404 . in more details , when the patient &# 39 ; s initial position is recumbent , first cable 141 , second cable 142 , and third cable 143 are controlled simultaneously to lift patient so that the recumbent posture is achieved . on the other hand , when the patient needs to change from recumbent to seated , only first cable 141 and second cable 142 are pulled up so as to cause the patient to sit up . finally , at step 411 , the patient is transferred to a final destination . now , referring to fig5 , control panel 111 or remote control 500 is described in connection with operation of patient lift 100 described in fig1 - fig3 above . structurally , remote control 500 includes a first command 501 when said user switches from an automatic mode to a manual mode . as discussed above , when problem occurs with first motor 311 and second motor 312 , causing patient lift 100 to be immobile , first command button 501 is pressed to allow patient lift 100 to be operated manually . next , a situational command area 510 groups command buttons related to different situations in which a patient is transport . specifically , a second command button 511 is selected when a user or medical assistant intends to lift a patient from a recumbent position to a seated position on foldable chair 120 of patient lift 100 . a third command button 512 is selected when the user lifts patient from foldable chair 120 of patient lift 100 to a recumbent position in a different location . a completion command button ( or “ ok button ) 515 is selected when a command selected by the user is final and micro - controller 111 performs the selected command ( s ). otherwise , micro - controller 111 waits for another command to be entered , wherein when two command buttons are entered and then completion command button 515 is pressed , micro - controller 111 performs the two selected command buttons . next , continuing with fig5 , a fourth command button 513 is selected when the user lifts a patient from a seated position to foldable chair 120 on patient lift 100 . a fifth command button 514 is selected when the user lifts a patient from foldable chair 120 of patient lift 100 to another seated position in a different location . a sixth command button 530 is selected when the user controls the movement of patient lift 100 including increasing , decreasing the speed of patient lift 100 , moving forward , turning left , turning right , and reversing of patient lift 100 . in one embodiment , sixth command button 530 can be a joystick . in another embodiment , sixth command button 530 can be configured to include forward arrow , backward arrow , left arrow , and right arrow . continuing again with fig5 , a command group 520 is used when the user wants to rotate a patient by rotator 155 . command group 520 includes seventh command button 521 for is selected when the user rotates rotator 155 in a counter - clockwise direction . finally , an eighth command button 522 is selected when the user rotates rotator 155 in a counter direction . in operation , upon selecting the second command 511 and completion command button 515 are selected , micro - controller 111 causes said sixth motor 181 and seventh motor 182 to operate first cable 141 , second cable 142 , and third cable 143 simultaneously so that patient is assisted to sit on foldable chair 120 of patient lift 100 . next , when second command button 511 and third command button 512 are selected and then completion command button 515 are selected , micro - processor 111 is operable to maintain the lengths of first cable 141 , second cable 142 , and third cable 143 . finally , micro - processor 111 transfers patient from seated position to a recumbent position in a different location . in another occasion , when completion command button 515 is selected after fourth command 513 is selected , micro - controller 111 causes sixth motor to maintain the lengths of first cable 141 , second cable 142 , and third cable 143 so that patient is transferred from a seated position to foldable chair 120 of patient lift 100 . in another situation , when fourth command button 513 and fifth command button 514 are selected , and then completion command button 515 is selected afterward , micro - controller 111 causes sixth motor 181 to cause to maintain the lengths of first cable 141 , second cable 142 , and third cable 143 so that patient is transferred to another seated position at a different location . continuing with the operation of patient lift 100 as described in fig5 , when second command 511 and fifth command 514 are selected together and then completion command 515 is selected , micro - controller 111 causes said sixth motor 181 and seventh motor 122 to operate first cable 141 , second cable 142 , and third cable 143 simultaneously . then patient is transferred to another seated position at a different location . finally , when fourth command 513 and third command button 512 are selected together and completion command button 515 is selected , micro - controller 111 causes sixth motor 181 to operate first cable 141 and said second cable 142 together and seventh motor 182 to maintain third cable 143 and then to transfer patient to a recumbent position at a different location . the foregoing description details certain embodiments of the invention . it will be appreciated , however , that no matter how detailed the foregoing appears in text , the invention can be practiced in many ways . as is also stated above , it should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re - defined herein to be restricted to including any specific characteristics of the features or aspects of the invention with which that terminology is associated . the scope of the invention should therefore be construed in accordance with the appended claims and any equivalents thereof .
a method and apparatus for lifting a patient is disclosed to include a base with wheels on the back side and casters on the front side ; a pair of extendable legs extended or withdrawn from the frontal side of the base to maintain balance when lifting a patient ; vertical masts connected to a three - prong hanger ; three durable cables used with a sling assembly to lift the patient ; a foldable chair provides temporary rest for the patient on the patient lift ; and a control panel having a micro - controller for remotely controlling the patient lift .