Patent Publication Number: US-8984686-B2

Title: Platform of electric-movable bed for bedsore prevention capable of adjusting shaft according to user body type and method for controlling position change period thereof

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     This application is a national Stage Patent Application of PCT International Patent Application No. PCT/KR2011/004208, filed on Jun. 8, 2011 under 35 U.S.C. §371, which claims priority of Korean Patent Application Nos. 10-2010-0054512, filed on Jun. 9, 2010 and 10-2010-0054513 filed on Jun. 9, 2010, which are all hereby incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a electric-movable bed for a patient, more particularly, to a platform for an electric-movable bed which is able to provide an optimized shaft for a patient by changing a shaft according to a patient body type and to automatically change a patient position to prevent bedsores generated in a patient lying on a bed. 
     BACKGROUND 
     Generally, a serious patient such as a quadriplegic who is not able to move about freely spend most time of a day on lying on a bed or sitting on a wheelchair, with help of care workers or family dependents. As the old population has been increasing, the population lying on beds because of old age or dementia has been increasing. 
     However, overpressure is locally applied to a patient lying or sitting for a long time in the back, bottom touching a surface of a bed or wheelchair. A blockage of capillary blockage is continued by such overpressure constantly and repeatedly applied to the local part of the patient body. Accordingly, blood fails to flow through a skin tissue of the body part only to generate bedsores. 
     The tension applied to the location of the bedsore and the time of the tension activation can be important in this case. In an early stage, there is no damage to the skin tissue but discoloration on the location. As the bedsore is advanced, a sore starts to occur in a skin epidermal tissue and the inner skin under the skin epidermal tissue happens to be damaged. Even in a severe case, the bedsore can damage to the muscle or osseous tissue. 
     Moreover, such the patient might have a great pain enough to destroy the quality of the life. First of all, in case the bedsore happens to the patient unable to move freely, the recovery speed is slow according to characteristics of the elderly patient or patient unable to move freely and it might be quite difficult for such the patient to recover from the bedsore and the sore is subject to aggravation. There may be quite social costs of the economical loss required by the expense of treating the bedsore and of the death of the patient. 
     To solve such problem, there are many hospitals using electric-movable beds recently. 
     Such an electric-movable bed  10  can have a back supporting part  12  supporting the human back and a leg supporting part  14 , of which angles are adjusted in an electric type to change the patient&#39;s position easily to make easy to take care of the patient advantageously. 
     However, every patient has a different body type and the locations of the bottom and knee can be differentiated according to the body type. In a conventional electric-movable bed, a rotating portion is fixed. Accordingly, the patient might have a wrong position if the patient&#39;s body type is not fitted to the electric-movable bed, only to cause the patient&#39;s uncomfortable feeling. Also, if such a wrong position is repeated for a long time, musculoskeletal system disorder might be caused. As the conventional electric-movable bed has no function of changing the patient body type periodically and automatically, such that the load and shear force applied to a specific skin location only to generate bedsores disadvantageously. 
     Moreover, to prevent the bedsores from occurring in the patient lying on the bed, the angle of the supporting part provided in the electric-movable bed is changed on a regular cycle. Even when changing the position of the patient with the change of the angle on the regular cycle, such a position change cycle might be applied uniformly, not be optimized according to the patient&#39;s sex, age, weight and other personal characteristics of the patient. Accordingly, optimized position change cycle for each patient cannot be provided disadvantageously. 
     DISCLOSURE 
     Technical Solution 
     To achieve these objects and other advantages and in accordance with the purpose of the embodiments, as embodied and broadly described herein, a platform of an electric-movable bed for preventing bedsores capable of changing a shaft includes a plate unit comprising a plurality of main plates rotatably provided to support the human body, a plurality of sub plates rotatably and hingedly coupled to the main plates, respectively, and a locking part provided between each main plate and each sub plate to enable or lock the rotation of each main plate or sub plate, the plate unit configured to selectively rotate a corresponding portion to a position of the joint according to a user&#39;s body type; a first driving unit configured to tilt an upper part of the human body lying on the plate unit; and a second driving unit configured to tilt a lower part of the human body lying on the plate unit. 
     The plurality of the sub plates may be provided, corresponding to a location of the human bottom and a location of the human knees. 
     The locking part may include an upper locking body provided in a lateral surface of a main plate or a sub plate out of neighboring main or sub plates; a lower locking body rotatably provided under the other main or sub plate out of two neighboring main or sub plates, the lower locking body extended to a lower portion of the upper locking body; and a locking rod coupled to one of the upper and lower locking bodies, with being extended to be selectively fixed to the other one, the locking rod configured to selectively lock the rotation of the neighboring main or sub plates. 
     The lower locking body may be rotatable in the same direction as the rotational direction of the main plates and the sub plates. 
     The locking rod may be rotatably coupled to the upper locking body and selectively fixed to the lower locking body. 
     A sensor may be provided in the locking part to sense whether the upper locking body, the lower locking body and the locking rod composing the locking part are connected and locked to each other. 
     The first driving unit may include a first base; a first motor provided in the first base; a first screw shaft rotated by the rotation of the first motor, with being extended in a longitudinal direction of the human body lying on the plate unit, the first screw shaft having a screw thread formed in an outer circumferential surface thereof; a first hinge formed in a position extended upward from the first base; a first rail provided in the first base in the longitudinal direction of the human body lying on the plate unit; a first slider engaging with the first screw shaft rotated by the first motor to be transferred along the first rail together with the rotation of the first screw shaft, the first slider having a second hinge formed at a position having a different height from the height of the first hinge; and a first bar hingedly coupled to the first hinge and hingedly coupled to the second hinge at a position having a different height from the first hinge, to rotate on the first hinge as the first slider is transferred to make an end thereof move the main or sub plate upward. 
     A first roller may be provided in an end of the first bar which contacts with the main or sub plate. 
     The platform of the electric-movable bed for preventing bedsores capable of changing the shaft may further include a position adjusting unit configured to adjust a position of the first driving unit. 
     The position adjusting unit may include a under base provided under the first base; a under rail provided in the under base to slidingly support the first base; and a fixing part configured to fix the position of the first base by restricting the moving of the first base along the under rail. 
     The fixing part may include a plurality of fixing grooves formed in the under base along a longitudinal direction; a fixing projection rotatably projected from the first base downward to be inserted in one of the fixing grooves to fix the first base to the under base; and a lever configured to rotate the fixing projection to selectively separate the fixing projection from the fixing groove. 
     The second driving unit may include a second base; a second motor provided in the second base; a second screw shaft rotated by the rotation of the second motor, with being extended in a longitudinal direction of the human body lying on the plate unit, the second screw shaft having a screw thread formed in an outer circumferential surface thereof; a third hinge formed in a position extended upward from the second base; a second rail provided in the second base in the longitudinal direction of the human body lying on the plate unit; a second slider engaging with the second screw shaft rotated by the second motor to be transferred along the second rail together with the rotation of the second screw shaft, the second slider having a fourth hinge formed at a position having a different height from the height of the third hinge; and a second bar hingedly coupled to the third hinge and hingedly coupled to the fourth hinge at a position having a different height from the third hinge, to rotate on the third hinge as the second slider is transferred to make an end thereof move the main or sub plate upward. 
     A second roller may be provided in a contacting portion of the second bar with the main or sub plate. 
     The platform of the electric-movable bed for preventing bedsores capable of changing the shaft may further include an input unit configured to input data on the user&#39;s physical conditions thereto. 
     In another aspect of the present invention, a method for controlling a posture changing cycle of a platform of an electric-movable bed for preventing bedsores capable of changing a shaft comprising a plate unit configured to allow a user to lie thereon, the plate unit comprising a plurality of rotatable plates to form a supporting surface to change a user&#39;s posture; a driving unit configured to change an angle of each plate; and an input unit configured to input data on a user&#39;s physical conditions thereto, the platform further comprising a control unit having a database for a risk level of bedsore occurrence at a specific location of the human body for a user&#39;s specific posture, wherein the control unit applies data on the user&#39;s physical conditions inputted based on the data for the risk level of the bedsore occurrence at the specific location of the human body for the user&#39;s specific posture input to the database to drive the driving unit to prevent the bedsores to change a posture of the plate unit on a predetermined cycle. 
     Data on a risk level of bedsore occurrence for each specific location of the human body based on the posture maintaining time for maintaining a specific posture may be inputted to the database. 
     The risk level of the bedsore occurrence may be configured to evaluate the risk level of the bedsore occurrence as data including at least one of a pressure applied to each location of the human body, shear forces, tcpCO2 and tcpO2. 
     The risk level of the bedsore occurrence may be configured to evaluate the risk level of the bedsore occurrence based on at least one of the user&#39;s weight, age and sex. 
     A weighted value of bedsore occurrence risk based on the user&#39;s specific disease or physical constitution may be applied to the database. 
     Advantageous Effects 
     The platform of the electric-movable bed for preventing bedsores capable of changing the shaft based on a user&#39;s body constitution and a method for controlling a posture changing cycle thereof according to the present invention have following advantageous effects. 
     First of all, one shaft fitted to the patient&#39;s body constitution can be selectively rotated out of the plurality of the shafts. Accordingly, the patient may lie on the bed more comfortably and various diseases generated by the wrong postures can be prevented. Accordingly, the patient&#39;s life may be enhanced. 
     Furthermore, the optimized posture changing cycle for each user can be provided and the user may feel comfortable. Also, the bedsore occurrence possibilities can be lowered remarkably. Together with the enhancement of the user&#39;s life quality, the care&#39;s improved convenience and the reduction of the treatment costs can be expected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a conventional electric-movable bed; 
         FIG. 2  is a perspective view illustrating one embodiment of a platform for an electric-movable bed that is able to change a shaft according to a user&#39;s body type; 
         FIG. 3  is a side view of  FIG. 2 ; 
         FIG. 4  is a perspective view illustrating a locking part of the platform shown in  FIG. 2 , which is in an unlocked state; 
         FIG. 5  is a side view of the  FIG. 4 ; 
         FIG. 6  is a perspective view illustrating a locking part of the platform shown in  FIG. 2 , which is in a locked state; 
         FIG. 7  is a side view of  FIG. 6 ; 
         FIG. 8  is a side view illustrating a first main plate of a plate unit provided in the platform shown in  FIG. 2 , which is rotated with respect to a first variable hinge; 
         FIG. 9  is a side view illustrating the first main plate of the plate unit which is rotated with respect to a second hinge; 
         FIG. 10  is a side view illustrating the first main plate of the plate unit which is rotated with respect to a third hinge; 
         FIG. 11  is a side view illustrating a fourth main plate of the plate unit which is rotated with respect to a fourth hinge; 
         FIG. 12  is a side view illustrating the fourth main plate of the plate unit which is rotated with respect to a fifth hinge; 
         FIG. 13  is a perspective illustrating a first driving unit of  FIG. 2 ; 
         FIG. 14  is a side view illustrating the first driving unit of  FIG. 13 ; 
         FIG. 15  is a side view illustrating a first bar of the first driving unit shown in  FIG. 14 , which is rotated to move upward; 
         FIG. 16  is a perspective view illustrating a second driving unit of  FIG. 2 ; 
         FIG. 17  is a side view illustrating a second driving unit of  FIG. 16 ; 
         FIG. 18  is a side view illustrating a second bar of the second driving unit of  FIG. 16 , which is rotated to move upward; 
         FIG. 19  is a diagram illustrating a tilted angle of the first main plate according to rotation of a shaft provided in the first main plate and the position of the first driving unit, including: 
         FIG. 19(   a ) is a diagram illustrating change of the tilted angle of the first main plate according to the motion of the shaft of the first main plate, when the position of the first driving unit is fixed; and 
         FIG. 19(   b ) is a diagram illustrating a tilted angle of the first main plate according to the moving position of the first driving unit; 
         FIG. 20  is a perspective view illustrating a position adjusting part of the platform shown in  FIG. 2 ; 
         FIG. 21  is a perspective view illustrating the position adjusting part of  FIG. 20 , seen at another angle; 
         FIG. 22  is a side view illustrating the plate unit of  FIG. 2  which has a first posture; 
         FIG. 23  is a side view illustrating the plate unit of  FIG. 2  which is in a second posture; 
         FIG. 24  is a side view illustrating the plate unit of  FIG. 2  which is in a third posture; 
         FIG. 25  is a side view illustrating the plate unit of  FIG. 2  which is in a fourth posture; 
         FIG. 26  is a diagram illustrating one example of database according to another aspect of the present invention; and 
         FIG. 27  is a diagram illustrating another example of the database according to the aspect of the present invention shown in  FIG. 26 . 
     
    
    
     BEST MODE 
     Embodiments of the present invention will be described in detail in reference to the accompanying drawings and contents disclosed in the drawings and the present invention is not limited to the embodiments. Reference may now be made in detail to specific embodiments, examples of which may be illustrated in the accompanying drawings. Wherever possible, same reference numbers may be used throughout the drawings to refer to the same or like parts. 
     A platform for an electric-movable bed capable of adjusting a shaft based on a user&#39;s body type (hereinafter, a platform) according to one embodiment of the present invention may include a plate unit  102 , a first driving unit  150 , a second driving unit  170  and a frame  106 . 
     As shown in  FIGS. 2 and 3 , the plate unit  102  may include main plates  112 ,  114 ,  116  and  118 , sub plates  122 ,  124  and  126  and a locking part  140 . 
     The main plates  112 ,  114 ,  116  and  118  may be configured of a first main plate  112  supporting the human back, a second main plate  114  supporting the human bottom, a third main plate  116  supporting the human thighs and a fourth plate  118  supporting human calves. 
     A first sub plate  122  and a second sub plate  124  are provided between the first main plate  112  and the second main plate  114 . The first main plate  112 , the first sub plate  122 , the second sub plate  124  and the second main plate  114  are rotatably connected with neighboring main plates or sub plates by a hinge, respectively. 
     Also, a third sub plate  126  may be provided between the third main plate  116  and the fourth main plate  118 . The first main plate  116 , the third sub plate  126  and the fourth main plate  118  are rotatably connected with neighboring main plates or sub plates by a hinge. 
     No sub plate is provided between the second main plate  114  and the third main plate  116  and the second main plate  114  and the third main plate  116  are directly connected with each other by a hinge. 
     The locking parts  140  are provided between the main plates and the sub plates, respectively, except between the second main plate  114  and the third main plate  116 , only to selectively restrict the rotations between the main plates and the sub plates. The locking parts  170  will be described in detail later. 
     In the description of this embodiment, the hinge between the first main plate  12  and the first sub plate  122  may be referenced to as ‘a first variable hinge  131 ’. The hinge between first sub plate  122  and the second sub plate  124  is referenced to as ‘a second variable hinge  132 ’. The hinge between the second sub plate  124  and the second main plate  114  may be referenced to as ‘a third variable hinge’. 
     Moreover, the hinge between the third main plate  116  and the third sub plate  126  may be referenced to as ‘a fourth variable hinge  134 ’ and the hinge between the third sub plate  126  and the fourth main plate  118  may be referenced to as ‘a fifth variable hinge  135 ’. 
     Meanwhile, the hinge between the second main plate  114  and the third main plate  116  with no locking part  140  may be referenced to as ‘a fixed hinge  137 ’. 
     In other words, the first to third variable hinges  131  to  133  are corresponding to the locations of the human hip joints. The fourth and fifth variable hinges  134  and  135  are corresponding to the human knee locations. 
     The first driving unit  150  is a component element for tilting the first main plate  112  to raise an upper part of the human body. 
     The second driving unit  170  is a component element for tilting the third main plate  116  to support the human thigh locations to close the human legs. 
     The frame  106  supports the plate unit  102 . The first driving unit  150  and the second driving unit  170  are mounted in the frame  106 . For moving convenience sake, the frame  106  may include a handle and wheels located in a lower portion thereof. Of course, a locking mechanism for locking the rotation of the wheels may be provided in the wheels  108 . 
     The first driving unit  150  and the second driving unit  170  will be described in detail later. The locking parts  140  will be described in detail as follows. 
     As shown in  FIGS. 2 and 3 , the locking parts  140  may be provided in the first variable hinge  131  and the fifth variable hinge  135 , respectively. 
     More specifically, as shown in  FIGS. 4 to 7 , the restricting part  140  may include an upper locking body  141 , a lower locking body  142  and a locking rod  144 . 
     The upper locking body  141  may be formed in a lateral portion of either of two neighboring main or sub plates  112 ,  114 ,  116  and  118  or  122 ,  124  and  126 . 
     The lower locking body  142  is provided in opposite to the upper locking body  141 . The lower locking body  142  is rotatably coupled to a bottom surface of another main plate or sub plate located in opposite to the main or sub plate where the upper locking body  141  is provided. When it is unfolded, the lower locking body  142  may face the upper locking body  141 , with being positioned under the upper locking body  141 . 
     The locking rod  144  has an end hingedly coupled to the upper locking body  141  and the other end extended to be selectively fixed to the lower locking body  142 . 
     Also, an inserting hole  143  is formed in the lower locking body  142  to pass the locking rod  144  there through. 
     A fastening bolt  145  having a larger area than the inserting hole  143  is provided in an edge of the locking rod  144  where the lower locking body  142  is coupled. When the locking rod is coupled to the lower locking body  142 , the fastening bolt may fasten the coupling. 
     Accordingly, as shown in  FIGS. 4 and 5 , the locking part  140  is unlocked when the locking rod  144  is not coupled to the lower locking body  142 . As shown in  FIGS. 6 and 7 , the locking rod  144  is positioned in the inserting hole  143  of the lower locking body  142  in a state where the lower locking body  142  is unfolded to be positioned under the upper locking body  141 . After that, the fastening bolt  145  is fastened to securely fasten the lower locking body  142 , only to complete the locking of the locking part  140 . 
     In other words, the first to fifth variable hinges  131  to  135  are rotated or locked according to the locking of the locking part  140 , only to adjust the position rotated based on the user&#39;s body type as shown in  FIGS. 8 to 12 . 
     Moreover, a sensor  146  may be further provided to sense which one of the locking parts  140  provided in the first to fifth variable hinges  131  to  135 , respectively, is in a locked state. 
     Specifically, as shown in  FIGS. 4 and 5 , the sensor  146  is provided under the upper locking body  141  and it includes a sensed part  147  extended from the lower locking body  142 , to be sensed by the sensor  146  by facing the sensor  146  when the lower locking body  142  is unfolded. In other words, when the lower locking body  142  is positioned under the upper locking body  141  as a locked position, the sensed part  147  is overlapped with the sensor  146  and the sensor  146  senses that the locking part  140  is in the locked state. 
     Also, as shown in  FIGS. 2 and 3 , an input unit  103  may be provided in one surface of the plate unit  102  or the frame  106 . The input unit  103  may consist of a display  105  and a keypad  107 . The user may select an operational mode of the platform  100 , using the display  105  and the keypad  107 , and he or she may input a variety of information on body conditions including the user&#39;s age, height and weight and physical constitution or diseases. Although not shown in the drawings, a terminal connected to an external device and the like may be provided in the input unit  103  to input or output various data. 
     The first driving unit  150  is a component element for tilting the first main plate  112  to raise the upper part of the human body. As shown in  FIGS. 13 to 15 , the first driving unit  150  may include a first base  151 , a first motor  152 , a first screw shaft  153 , a first hinge  154  a first rail  155 , a first slider  156  and a first bar  159 . 
     The first base  151  is provided underneath the plate unit  102  in the frame  106 . The first motor  152  is provided in the first base  151  to provide a clockwise/counter-clockwise rotational force. The first screw shaft  153  is rotated in a clockwise direction by the first motor  152  and a screw thread is formed in an outer circumferential surface of the first screw shaft  153  and it is extended in a longitudinal direction of the human body lying on the plate unit  102 . The first hinge  154  is extended upward from the first base  151 . The first rail  155  is formed in a longitudinal direction of the human body lying on the plate unit  102 . 
     The first slider  156  is provided beyond the first rail  155  and it engages with the first screw shaft  153  to sliding-reciprocate the first rail  155  along the clockwise/counter-clockwise direction rotation. The second hinge  157  is provided in the first slider  156 . 
     A middle portion of the first bar  159  is hingedly coupled to the first hinge  154  and an end of the first bar  159  is connected to the second hinge  157  via the first link  158 . At this time, the linked portion of the first bar  159  with respect to the second hinge  157  may be positioned at a position having the different height from the height of the first hinge  154 . For that, an end of the first bar  159  may be bending downward and the bent portion is linked to the second hinge  157 . The other end of the first bar  159  is extended a predetermined length and a first roller  161  is provided in the end of the first bar  159 . The first bar  159  may be arranged in a position corresponding to a lower portion of the first main plate  112 . The first roller  161  may be provided in a predetermined portion of the first bar toward the human head. 
     Accordingly, when the first motor  152  is rotated in a clockwise direction as shown in  FIG. 15 , the first screw shaft  153  is rotated by the rotational force of the first motor  152 . As it is moving, the first slider  156  engaging with the first screw shaft  153  pulls the end of the first bar  159  via the first link  158  and the portion of the first bar  159  coupled to the first link  158  is lower than the first hinge  154 . As a result, the other end of the first bar  159  is moved upward and the first bar  159  is rotated along the upward moving. After that, the first roller  161  provided in the end of the first bar  159  lifts the first main plate  112  and the first main plate  112  is rotated with respect to one of the first to third variable hinges  131  to  133  locked by no locking parts, to be tilted. 
     When the first motor  152  is rotated in the counter-clockwise direction, the reverse driving is performed and the first bar  159  is dropped and the first main plate  112  is rotated to be unfolded. 
     The second driving unit  170  is a component for tilting the first main plate  116  and the fourth main plate  118  to raise the human legs. As shown in  FIGS. 16 to 18 , the second driving unit  170  may include a second base  171 , a second motor  172 , a second screw shaft  173 , a third hinge  174 , a second rail  175 , a second slider  176  and a second bar  179 . 
     The second driving unit  170  has a similar configuration to the first driving unit  150  described above. Specifically, the second base  171  is provided under the plate unit  102  in the frame  106 . The second motor  172  is provided in the second base  171  to provide a clockwise/counter-clockwise rotational force. The second screw shaft  173  is rotated in a clockwise direction by the second motor  172  and a screw thread is formed in an outer circumferential surface of the second screw shaft  173  and it is extended in a longitudinal direction of the human body lying on the plate unit  102 . The third hinge  174  is extended upward from the second base  171 . The second rail  175  is formed in a longitudinal direction of the human body lying on the plate unit  102 . 
     The second slider  176  is provided beyond the second rail  175  and it engages with the second screw shaft  173  to sliding-reciprocate the second rail  175  along the clockwise/counter-clockwise direction rotation. The fourth hinge  177  is provided in the second slider  176 . 
     A middle portion of the second bar  179  is hingedly coupled to the third hinge  174  and an end of the second bar  179  is connected to the fourth hinge  177  via the second link  178 . At this time, the linked portion of the second bar  179  with respect to the fourth hinge  177  may be positioned at a position having the different height from the height of the third hinge  174 . For that, an end of the second bar  179  may be bending downward and the bent portion is linked to the fourth hinge  177 . The other end of the second bar  179  is extended a predetermined length and a second roller  181  is provided in the end of the second bar  179 . The second bar  179  may be arranged in a position corresponding to a lower portion of the third main plate  116 . The second roller  181  may be provided in a predetermined portion of the second bar  179  toward the human head. 
     Accordingly, when the second motor  172  is rotated in a clockwise direction as shown in  FIG. 18 , the second screw shaft  173  is rotated by the rotational force of the second motor  172 . As it is moving, the second slider  176  engaging with the second screw shaft  173  pulls the end of the second bar  179  via the second link  178  and the portion of the second bar  179  coupled to the second link  178  is lower than the third hinge  174 . As a result, the other end of the second bar  179  is moved upward and the second bar  179  is rotated along the upward moving. After that, the second roller  181  provided in the end of the second bar  179  lifts the third main plate  116  and the first main plate  112  is rotated with respect to the fixed hinge  137 , as shown in  FIGS. 11 and 12  and  24  and  25 , and the fourth main plate  118  is rotated with respect to the fourth or fifth variable hinge  134  or  135  locked by no locking parts, to be tilted. 
     When the second motor  252  is rotated in the counter-clockwise direction, the reverse driving is performed and the second bar  259  is dropped and the third main plate  116  is rotated to be unfolded. 
     Meanwhile, as shown in  FIG. 19(   a ), the first driving unit  150  is driving to move the first bar  159  upward and the first main plate  112  is tilted. The lifted position of the first bar  159  provided in the first driving unit  150  is restricted and a tilted angle of the first main plate  112  can be changed based on which one of the first to third variable hinges  131  to  133  the first main plate  112  is rotated on. 
     Accordingly, as shown in  FIG. 19(   b ), a position adjusting unit  190  may be further provided to adjust the position of the first driving unit  150  to change the first main plate supporting point of the first driving unit  150 , such that the tilted angle of the first main plate  112  can be uniform even when the first main plate  112  is rotated on one of the first to third variable hinges  131  to  133 . 
     As shown in  FIGS. 20 and 21 , the position adjusting unit  190  may include an under base  191  and an under rail  192  and a fixing part  194 . 
     The under base  191  is provided under the first base  151  of the first driving unit  150  within the frame  106 . The under rail  192  is provided in the under base  191  and it slidingly supports the first base  151 . At this time, the under rail  192  may be arranged in a longitudinal direction of the user&#39;s body. 
     The fixing part  194  selectively restricts the moving of the first base  151  along the under rail  192 , to fix the position of the first base  151 . The fixing part  194  may include a fixing groove  193 , a fixing projection  194  and a lever  195 . 
     A plurality of fixing grooves  193  may be formed in a top surface of the under base  191 . The fixing projection  194  is projected downward with respect to the first base  151  and it is rotatable with respect to the first base  151 . The fixing projection  194  is inserted in one of the fixing grooves  193  to prevent the moving of the first base  151 . The lever  195  rotates the fixing projection  194  to separate from the fixing groove  193  or to be inserted in one of the fixing grooves  193 . 
     The fixing parts mentioned above are provided in both opposite sides of the first driving unit  150 . The levers  195  provided in the sides are connected with each other by a third link  196 . Even when one of the levers  195  is rotated, the other one is rotated together to separate or insert each fixing projection  194  from or in each fixing groove  193 . 
     Accordingly, the first base  151  is slidingly moving along the under rail  192  in a state where the fixing projection  194  is separated from the fixing groove  193  by rotating the lever  195  upward. After each of the locking units  140  is locked or unlocked to make the rotation axis of the first main plate  112  one of the first to third variable hinges  131  to  133 , the position of the position adjusting unit  190  is adjusted and the lever  195  is rotated to the original position to insert the fixing projection  194  in the fixing groove  193  to fix the position of the first base  151 . Accordingly, the position of the first driving unit  150  may be adjusted. 
     A third roller  109  is provided in an end of the frame  106  toward the human feet to support the fourth main plate  118 . 
     As shown in  FIGS. 22 to 25 , one to rotate out of the variable hinges  131 ,  132 ,  133 ,  134  and  135  of the plate unit  102  is determined to be fitted to the user&#39;s body type. After that, the first driving unit  150  and the second driving unit  170  are driven to tilt the plate unit  102 . According to the user&#39;s taste, a mattress (not shown) or the like may be spread on the plate unit  102 . 
     A state where the plate unit  102  is flat may be referenced to as ‘a first posture’ as shown in  FIG. 22 . A state where the first main plate  112  is erected to raise the upper body part of the patient may be referenced to as ‘a second posture’ as shown in  FIG. 23 . A state where the first main plate  112  is flat, with the third and fourth main plates  116  and  118  being tilted, to raise the patient&#39;s knees may be referenced to as ‘a third posture’ as shown in  FIG. 24 . Also, as shown in  FIG. 25 , a state where the first, third and fourth main plates  112 ,  116  and  118  are tilted to raise the patient&#39;s upper body part, together with raising the knees may be referenced to as ‘a fourth posture’. 
     Moreover, a control unit (not shown) is provided in the platform  100  to control the first driving unit  150  and the second driving unit  170 . The control unit fabricated in a substrate type may be provided in the platform or embedded in the input unit  103 . 
     The control unit includes a database for information on a risk level of bedsore occurrence at a specific location of the human body for each specific posture of the user lying on the plate unit  102 . 
     As shown in  FIGS. 26 and 27 , various bedsore inducing factors are measured to evaluate a risk level of bedsore occurrence at the specific location of the human body for each specific posture and the evaluated data is input to the database, which may be the result deducted from many experiments. 
     More specifically, the bedsores may be generated by factors including the pressure, the friction force and the shear forces applied to the human skin. Also, the occurrence of the bedsores may be related to a transcutaneous gas partial pressure of the human skin. In this instance, the transcutaneous gas partial pressure may be tcpO2 or tcpCO2, for example. 
     In other words, as the pressure, friction force and shear forces are getting larger and as the time taken to apply them is getting longer, a risk level of the transcutaneous gas partial pressure is getting high. As tcpCO2 is getting larger and as tcpO2 is getting smaller, a risk level of the transcutaneous gas partial pressure is getting high. 
     That is, the risk level of the bedsore occurrence is the data including at least one of the pressure and shear forces for each specific location of the human body, tcpCO2 and tcpO2. The risk level is evaluated based on the free posture maintaining time with respect to each specific location of the human body at a specific posture. 
     Also, the size of the force applied to each location of the human body such as a mean physiognomy or scapula and the risk of the bedsore occurrence may be differentiated. Data on the bedsores occurrence factors for each location of the human body can be input in the database. 
     Also, the size of the force applied to each location of the human body may be differentiated according to the postures of the human body and the risk of the bedsore occurrence may be differentiated. Data on the bedsore factors for each location of the human body for each posture of the platform  100  may be input in the database. 
     The risk level of the bedsore occurrence may be differentiated according to the user&#39;s weight, age and sex. Data on the risk level of the bedsore occurrence may be input in the database. 
     Accordingly, the data on the factors is input to the database and the data on the risk level of the bedsore occurrence for each location of the human body according to the posture maintaining time is input to the database. 
     Together with that, the physical constitution such as the skin subject to the bedsores or characteristics of diseases subject to the bedsores such as blood flow disorders may be closely related to the risk level of the bedsore occurrence. When such characteristics are inputted via the input unit, the control unit applies a weighted value to the data stored in the database. 
     Considering such the factors, the risk level of the bedsore occurrence applied to a specific location of the human body at a corresponding posture may be expected. To minimize the risk of the bedsore occurrence, the control unit drives the first driving unit  150  and the second driving unit  170  and controls to alternate maintaining one of the first to fourth postures for a predetermined time on a regular cycle. 
     Of course, even when one of the first to fourth postures is changed into another one, the order of the patient taking a posture not to apply the shear forces to the patient skin after slicked from the first main plate  112 , the order of driving the first and driving units, the tilted angle of each main plate and the posture changing time may be adjusted. The order or frequency of the taking each posture may be combined variously. 
     In the description of this embodiment, the platform  100  is taking one of the first to fourth postures. However, the present invention is not limited to the posture of the platform and it is possible to control the platform in various postures. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.