Abstract:
The present invention provides a height-adjustable pillow comprising: a lower member; an upper member which is disposed above the lower member, in such a way as to be able to move vertically relative to the lower member; and a raising and lowering device for adjusting the height of the upper member by moving the upper member.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of pending International Patent Application PCT/KR2015/002002 filed on Mar. 2, 2015, which designates the United States and claims priority of Korean Patent Application No. 10-2014-0024858 filed on Mar. 3, 2014, Korean Patent Application No. 10-2014-0024859 filed on Mar. 3, 2014, and Korean Patent Application No. 10-2015-0023432 filed on Feb. 16, 2015, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to a pillow and, more particularly, to a height-adjustable pillow, the height of which is able to be adjusted. 
       BACKGROUND OF THE INVENTION 
       [0003]    In general, a pillow serves to support the head of a user such that the user can remain in a comfortable position while sleeping, and thus generally has a predetermined height and a suitable cushioning function. Such a pillow includes a pillow body filled with a stuffing and a pillow cover covering the pillow body. The stuffing may be implemented as buckwheat chaff, rice chaff, latex, sponge, cotton, hair, a functional material, or the like. 
         [0004]    People sleep in a variety of postures, i.e. people lie on backs, sides, or stomachs. When a person rests with the head supported on a pillow while lying on his or her back, the back of the head, the cervical spine, and the back are substantially in line, such that the user may not be significantly uncomfortable even if the height of the pillow used is relatively low. However, when the person attempts to sleep on the side with the pillow of the same height, the cervical spine becomes curved due to the difference in the height between one shoulder and one side of the face, causing the person to be uncomfortable. In contrast, when a relatively higher pillow is used, the person may feel relatively comfortable when lying on the side. However, when the person lies on his or her back, the head may be raised, whereby discomfort is likely. 
       SUMMARY OF THE INVENTION 
       [0005]    Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose a height-adjustable pillow, the height of which is able to be adjusted to a height at which a user can feel comfortable. 
         [0006]    In order to achieve the above object, according to one aspect of the present invention, a height-adjustable pillow may include: a lower member; an upper member disposed on the lower member, the upper member being displaceable up and down with respect to the lower member; and a lifting unit adjusting a height of the upper member by displacing the upper member. 
         [0007]    The lifting unit may include: a pair of driving shafts horizontally extending through the lower member; rotary gears disposed on the pair of driving shafts, a rotary gear on one of the driving shafts being meshed with a corresponding rotary gear on the other of the driving shafts; and lifting members disposed on the pair of driving shafts, wherein the lifting members lie in horizontal positions or are erected to vertical positions in response to rotation of the driving shafts to move the lifting members up and down. 
         [0008]    One of the driving shafts may include a ratchet and a handle disposed thereon. The height-adjustable pillow may further include a stopper limiting free rotation of the ratchet to maintain the pair of driving shafts in a fixed position. 
         [0009]    The stopper may be disposed on a support shaft horizontally extending through the base, and may be meshed with or unmeshed from the ratchet in response to a longitudinal movement of the support shaft. An elastic spring may be disposed between the stopper and the lower member to surround the support shaft, so that the support shaft is placed in a set position. 
         [0010]    The lifting unit may include: a driving shaft horizontally extending through the lower member; bevel gears disposed on a front end of the driving shaft to convert longitudinal rotation of the driving shaft into lateral rotation; a driving gear section rotating in a lateral direction in concert with the bevel gears; a plurality of driven gear sections rotating in a lateral direction in concert with the driving gear section; and lifting portions disposed on top surfaces of the driven gear sections, each of the lifting portions including a plurality of step portions having different heights. 
         [0011]    The plurality of step portions of each of the lifting portions may be formed in a stepwise manner with different heights, with slopes alternating with the step portions. 
         [0012]    The upper member may have a plurality of contact members to be seated on corresponding step portions having same heights among the step portions of the lifting portions, so that the plurality of contact members are displaced up and down in response to rotation of the lifting portions. 
         [0013]    The lifting unit may include: a rotary member provided on a surface of one of the lower member and the upper member that faces the other of the lower member and the upper member such that the rotary member is rotatable about a vertical axis, the rotary member including a slope upwardly inclined in one direction along a circumference thereof about the axis and a plurality of holding step portions formed on the slope to continuously extend along a length of the slope such that the plurality of holding step portions are positioned at different heights; and a contact member provided one the other one of the lower member and the upper member such that the contact member is able to come into contact with one of the plurality of holding step portions depending on an angle of rotation of the rotary member. Each of the plurality of holding step portions includes a stepped surface and a connecting surface, the stepped surfaces of the plurality of holding step portions are arranged at predetermined distances in the length of the slope such that the stepped surfaces are spaced apart and positioned at different heights from each other, and the connecting surfaces of the plurality of holding step portions are formed as inclined surfaces connecting the stepped surfaces having different heights, respectively, such that the contact member is displaced up and down along one of the connecting surfaces to move to an adjacent one of the stepped surfaces when the rotary member is rotated. 
         [0014]    Each of the stepped surfaces may be downwardly inclined in one direction along the circumference about the axis. 
         [0015]    The height-adjustable pillow may further include a guide for guiding upward and downward displacement of the upper member. The guide includes a guide pin and a pin-receiving member having a guide hole in which a guide pin is received. The guide pin is provided on one of the upper member and the lower member, and the pin-receiving member is provided on the other of the upper member and the lower member. 
         [0016]    The height-adjustable pillow may further include an indicating unit for indicating a height of the upper member determined by the lifting unit. The indicating unit may include: a rack extending vertically downward from the upper member; a pinion meshed with the rack; and an indicating member disposed outside of the lower member to rotate along with the pinion, the indicating member having a height indicating portion. 
         [0017]    According to embodiments of the present invention, the height of the pillow is able to be adjusted to a height at which a user can feel comfortable, so that the user is more likely to soundly sleep. 
         [0018]    In particular, when the present invention is applied in facilities used by the public, customer satisfaction can be significantly improved, since every user can adjust the heights of a pillow according to his or her preference. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIGS. 1 and 2  are a perspective view and a front elevation view illustrating a height-adjustable pillow according to a first exemplary embodiment of the present invention; 
           [0020]      FIG. 3  is a perspective view illustrating the height-adjustable pillow shown in  FIG. 1 , from which the cushion is removed; 
           [0021]      FIGS. 4 and 5  are perspective views illustrating the height-adjustable pillow shown in  FIG. 3 , from which the cover is removed; 
           [0022]      FIGS. 6 and 7  are front cross-sectional views illustrating the height-adjustable pillow according to the first exemplary embodiment of the present invention; 
           [0023]      FIGS. 8 and 9  are perspective views illustrating the lift unit used in the height-adjustable pillow according to the first exemplary embodiment of the present invention; 
           [0024]      FIGS. 10 and 11  are plan views of  FIGS. 4 and 5 , respectively; 
           [0025]      FIG. 12  is a front elevation view illustrating a height-adjustable pillow according to a second exemplary embodiment of the present invention; 
           [0026]      FIG. 13  is an exploded perspective view illustrating the height-adjustable pillow illustrated in  FIG. 12 , from which the cushion is removed; 
           [0027]      FIG. 14  is a perspective view illustrating the lifting unit used in the height-adjustable pillow according to the second exemplary embodiment of the present invention; 
           [0028]      FIGS. 15 to 17  illustrate the operational relationship of the height-adjustable pillow according to the second exemplary embodiment of the present invention; 
           [0029]      FIG. 18  is a front elevation view illustrating a height-adjustable pillow according to a third exemplary embodiment of the present invention; 
           [0030]      FIG. 19  is an exploded perspective view illustrating the height-adjustable pillow illustrated in  FIG. 18 , from which the cushion is removed; 
           [0031]      FIG. 20  is a perspective view illustrating the lifting unit used in the height-adjustable pillow according to the third exemplary embodiment of the present invention; 
           [0032]      FIG. 21  is a configuration view illustrating portions of the lifting unit illustrated in  FIG. 20 ; and 
           [0033]      FIG. 22  is a perspective view illustrating the height adjusting unit used in the height-adjustable pillow according to the third exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. 
       First Embodiment 
       [0035]    A height-adjustable pillow according to a first exemplary embodiment of the present invention is illustrated in  FIGS. 1 to 11 . 
         [0036]    As illustrated in  FIGS. 1 to 5 , the height-adjustable pillow according to the first exemplary embodiment of the present invention includes a base  20 , a cover  30 , and a lifting unit  100 . The base  20  is a lower member in the shape of a box with the top surface thereof being open. The cover  30  is an upper member seated on the base  20  such that the cover  30  can be displaced up and down. The lifting unit  100  displaces the cover  30  up and down with respect to the base  20 . A cushion  40  is seated on the cover  30  to support the head. The cushion  40  is displaced up and down together with the cover  30  in response to the operation of the lifting unit  100 . 
         [0037]    As illustrated in  FIGS. 4 to 11 , the lifting unit  100  includes a pair of driving shafts  110  ( 112 ,  114 ) extending through the base  20  from the front end to the rear end (extending from the front to the rear), rotary gears  120  disposed on the pair of driving shafts  110  at predetermined distances, and lifting members  130  disposed on the pair of driving shafts  110  at predetermined distances. 
         [0038]    The rotary gears  120  disposed on the first driving shaft  112  of the pair of driving shafts  110  mesh with the rotary gears  120  disposed on the second driving shaft  114  of the pair of driving shafts  110 . 
         [0039]    The lifting members  130  extend in one direction to be substantially elliptical, respectively having one end disposed on the first driving shaft  112  or the second driving shaft  114 . That is, the lifting members  130  are disposed eccentrically. The lifting members  130  are disposed on the pair of driving shafts  110  such that the lifting members on one of the pair of driving shafts  110  oppose the lifting members on the other of the pair of driving shafts  110 . Thus, the lifting members  130  remain in horizontal positions to be in parallel to each other or are rotated to vertical positions to be in parallel to each other. The detailed operational relationship will be described later. 
         [0040]    A handle  140  is disposed on the front or rear end of one driving shaft of the pair of driving shafts  110 , and ratchets  150  inclined in one direction are disposed on one driving shaft of the pair of driving shafts  110  on which the handle  140  is disposed. The plurality of ratchets  150  are provided in a number equal to the number of the lifting members  130  and are configured such that each of the ratchets  150  is in close contact with the corresponding lifting member  130 . However, the number of the ratchets  150  is not limited to a specific number. 
         [0041]    In the first embodiment of the present invention, for the sake of convenience, it will be described that the handle  140  is disposed on the front end of the first driving shaft  112  and the plurality of ratchets  150  are disposed on the first shaft  112 . 
         [0042]    Stoppers  160  are disposed in the inner space of the base  20  to engage with the ratchets  150  and maintain the ratchets  150  in fixed positions when the ratchets  150  are rotated. The stoppers  160  are disposed on a support shaft  162  extending through the base  20 . Each of the stoppers  160  has an elastic member  160   a  extending from one portion thereof to maintain the fixed position. This imparts elasticity to the stopper  160  such that the stopper  160  rotates together with the support shaft  162  to a predetermined angle when external force having a predetermined intensity is applied thereto and then returns to the original position. 
         [0043]    An elastic spring  164  surrounding the support shaft  162  is disposed between the front-most stopper of the stoppers  160  disposed on the support shaft  162  and the inner surface of the front end of the base  20 . In addition, a lever  170  is disposed on the front end of the support shaft  162  to be exposed externally. The support shaft  162  moves in the front or back direction as the elastic spring  164  is compressed or restored in response to the lever  170  being pulled or the distal end of the support shaft  162  being pushed. 
         [0044]    In addition, as illustrated in  FIGS. 10 and 11 , the stoppers  160  are positioned on the same horizontal line as the ratchets  150  due to the tension of the elastic spring  164  to remain engaged with the ratchets  150 . In addition, when the rear end of the support shaft  162  is pushed forward or the lever  170  is pulled, the support shaft  162  is displaced forward along with the elastic spring  164  being compressed, so that the stoppers  160  disposed on the support shaft  162  are also displaced forward, thereby moving away from the same horizontal line as the ratchets  150 . When force of pushing the support shaft  162  or pulling the lever  170  in the position is released, the support shaft  162  returns to the original position due to the restoring force of the elastic spring  162 , whereby the stoppers  160  engage with the ratchets  150 , as illustrated in  FIG. 10 . 
         [0045]    For reference, the lifting members  130  disposed on the first driving shaft  112  have recesses  132  having a predetermined size such that the lifting members  130  in the horizontal position avoid interfering with the support shaft  162 . 
         [0046]    Seating portions  24  are formed on the inner surfaces of both walls of the base  20 , the cover  30  is seated on the seating portions  24 , and the cushion  40  is seated on the cover  30 . 
         [0047]    Thus, in the position in which the lifting members  130  are horizontal as in  FIG. 6 , the cover  30  is seated on the seating portions of the base  20 . When the lifting members  130  are rotated in the vertical direction as illustrated in  FIG. 7 , the cover  30  is displaced upwards from the seating portions  24  of the base  20  by the lifting members  130 . 
         [0048]    For reference, guide projections  22  for guiding the lifting of the cover  30  in the vertical direction extend on the surfaces of both walls of the base  20 , and prevention projections  32  for preventing the cushion  40  from derailing extend on the surfaces of both walls of the cover  30 . 
         [0049]    The operational relationship of the height-adjustable pillow according to the first exemplary embodiment of the present invention will be described as follows: 
         [0050]    First, as illustrated in  FIGS. 4 and 6 , in the position in which the lifting members  130  are seated on the seating portions of the base  20  and are in the horizontal positions, the height of the pillow remains in the lowest position. 
         [0051]    In this position, a user may rotate the handle  140  disposed on one end of one of the pair of driving shafts  110  in one direction to raise the height of the pillow. That is, as illustrated in  FIG. 2 ,  FIG. 5 , and  FIG. 7 , when the handle  140  is rotated in one direction, the first driving shaft  112  on which the handle  140  is disposed rotates along with the handle  140 , so that the ratchets  150  disposed on the first driving shaft  112  rotate in one direction on the stoppers  160 . For example, when the handle  140  disposed on one end of the first driving shaft  112  is rotated to the right, the ratchets  150  disposed on the first driving shaft  112  responsively rotate to the right while clicking with the stoppers  160 . 
         [0052]    In this case, the elasticity of the stoppers  160  acts when the elastic members  160   a  are slightly pressed, allowing the ratchets  150  to rotate in one direction. Here, since the first driving shaft  112  is also rotated to the right, the lifting members  130  are also rotated together with the rotary gears  120 , whereby the lifting members  130  are rotated from the horizontal positions to the vertical positions. 
         [0053]    Since the rotary gears  120  of the first driving shaft  112  are meshed with the rotary gears  120  of the second driving shafts  1114 , when the first driving shaft  112  rotates to the right, the second driving shaft  114  rotates to the left, the opposite direction. This consequently rotates the lifting members  130  disposed on the second driving shaft  114  from the horizontal positions to the vertical positions in the direction opposite to the direction in which the lifting members  130  disposed on the first driving shaft  112  are rotated. 
         [0054]    As the lifting members  130  on both sides are vertically rotated as described above, the lifting members  130  displace the cover  30  upwards, so that the cushion  40  seated on the cover  30  is displaced upwards, thereby raising the height of the pillow. 
         [0055]    In this position, when the head is placed on the cushion  40  so that load is applied to the cushion  40  and the cover  30 , the ratchets  150  remain in the fixed positions held by the stoppers  160 . This consequently prevents the pair of driving shafts  110  from rotating in the opposite direction, whereby the height of the cushion  40  is maintained. 
         [0056]    Thus, the user can gradually raise the height of the cushion  40  to a desirable height using one-way rotation of the handle  140 . 
         [0057]    In the case of attempting to lower the height of the cushion  40  from the position in which the height of the cushion  40  has been raised as described above, the ratchets  150  and the stoppers  160  are unfixed, and then the handle  140  is rotated to the left, the opposite direction. That is, as illustrated in  FIGS. 10 and 11 , when the rear end of the support shaft  162  is pushed forwards or the lever  170  disposed on the front end of the support shaft  162  is pulled, the stopper disposed on the front end of the support shaft  162  is displaced a predetermined distance in the longitudinal direction while compressing the elastic spring  164 . Consequently, the stoppers  160  are moved away from the same horizontal line as the ratchets  150 , whereby the ratchets  150  are released to rotate to the left, in the opposite direction. 
         [0058]    Thus, when the handle  140  is rotated to the left in this position, the first driving shaft  112  and the rotary gears  120  are also rotated to the left, and at the same time, the lifting members  130  are rotated from the vertical positions to the horizontal positions. At this time, the second driving shaft  114  and the rotary gears  120  and the lifting members  130  disposed on the second driving shaft  114  are also rotated to the right. 
         [0059]    Responsively, the cover  30  is slowly displaced downwards along with the lifting members  130  that rotate horizontally. When the downward displacement of the cover  30  is finished, the support shaft  162  is released from being pressed or the lever  170  is released from being pulled. 
         [0060]    When the support shaft  162  is released from being pressed or pulled, the support shaft  162  is displaced to the original position in the longitudinal direction due to the restoring force of the elastic spring  164 . In other words, the stoppers  160  are positioned on the same line as the ratchets  150  and remain engaged with the ratchets  150 . In this position, it is possible to displace the cover  30  and the cushion  40  upwards again by rotating the handle  140 . 
         [0061]    For reference, in the first embodiment of the present invention, the ratchets  150  and the handles  140  have been described as being disposed on the first driving shaft  112  of the pair of driving shafts  110 . Alternatively, the ratchets  150  and the handles  140  may be disposed on the second driving shaft  114 . In this case, the support shaft  162  on which the stoppers  160  are disposed may be disposed to correspond to a portion on which the second driving shaft  114  is positioned. 
       Second Embodiment 
       [0062]    A height-adjustable pillow according to a second exemplary embodiment of the present invention is illustrated in  FIGS. 12 to 17 . 
         [0063]    As illustrated in  FIGS. 12 and 13 , the height-adjustable pillow according to the second exemplary embodiment of the present invention includes a base  20 A, a cover  30 A, and a lifting unit  200 . The base  20 A is a lower member in the shape of a box with the top surface thereof being open. The cover  30 A is an upper member seated on the base  20 A such that the cover  30 A can be displaced up and down. The lifting unit  200  displaces the cover  30 A up and down with respect to the base  20 A. A cushion  40 A is seated on the cover  30 A to support the head. The cushion  40 A is displaced up and down together with the cover  30 A in response to the operation of the lifting unit  200 . 
         [0064]    As illustrated in  FIGS. 13 and 14 , the lifting unit  200  includes a driving shaft  220  extending through one portion of the base  20 A, a pinion gear (or driving bevel gear)  222  disposed on the distal end of the driving shaft  220 , a ring gear (or driven bevel gear)  224  meshed with the pinion gear  222 , a driving gear section (or driving spur gear)  226  rotating along with the ring gear  224 , and a plurality of driven gear sections (or driven spur gears)  230  meshed and in concert with the driving gear section  226 . 
         [0065]    The pinion gear  222  disposed on the distal end of the driving shaft  220  and the ring gear  224  meshed with the pinion gear  222  form bevel gears to convert forward rotation of the driving shaft  220  into lateral rotation of the driving gear section  226 . A handle  210  is disposed on the front end of the driving shaft  220  to be exposed externally from the base  20 A. When the handle  210  is rotated, the driving shaft  220  is rotated, so that the bevel gears of the pinion gear  222  and the ring gear  224  are rotated. Consequently, the driving gear section  226  rotates, so that the drive gears sections  230  are responsively rotated. Lifting portions  234  are formed on the upper portions of the driven gears sections  230 . Each of the lifting portions  234  is configured such that the height thereof changes in a stepwise manner along the circumference thereof. 
         [0066]    The structure of the lifting portions  234  is illustrated in  FIGS. 14 to 17 . Each of the lifting portions  234  includes a first step portion A having a lowest height, a second step portion B with an upwardly-inclined first slope a formed between the first step portion A and the second step portion B, a third step portion C with an upwardly-inclined second slope b formed between the second step portion B and the third step portion C, a fourth step portion D with an upwardly-inclined third slope c being formed between the third step portion and the fourth step portion D, a fifth step portion E with an upwardly-inclined fourth slope c formed between the fourth step portion D and the fifth step portion E, a sixth step portion F with an upwardly-inclined fifth slope d formed between the fifth step portion E and the sixth step portion F, and a downwardly-inclined sixth slope f formed between the sixth step portion F and the first step portion A. In the second embodiment of the present invention, each of the lifting portions  234  has been described as having a stepped structure of a total six steps including the first step portion A to the sixth step portions F. However, each of the lifting portions  234  may have any stepped structure including two or more steps. The first step A to the sixth step F are disposed at equal distances from each other and are arranged radially around the driving gear section  226 . 
         [0067]    Contact members  32 A are formed on the bottom surface of the cover  30 A to be seated on the lifting portions  234  of the driven gears sections  230 , respectively. Thus, as the driven gears sections  230  are rotated, the contact members  32 A are positioned on the first step A to the sixth step F to be moved up and down. This will be described in detail later. 
         [0068]    One or more guide pins  34 A are formed on the bottom surface of the cover  30 A and pin-receiving members  22 A for guiding upward-downward movement of the guide pins  34 A are formed on the base  20 A in order to ensure that the contact members  32 A are moved up and down in the vertical direction without being laterally derailed when the contact members  32 A are moved up and down along with the rotation of the lifting portions  234  of driven gears sections  230 . Each of the pin-receiving members  22 A has a guide hole  24 A allowing the corresponding guide pin  34 A received therein to move up and down. Alternatively, pin-receiving members respectively having a guide hole may be formed on the cover  30 A, and guide pins may be formed on the base  20 A. 
         [0069]    The operational relationship of the height-adjustable pillow according to the second exemplary embodiment of the present invention will be described as follows: 
         [0070]    In the position in which the lifting unit  200  is disposed in the inner space of the base  20 A and the cover  30 A having the cushion  40 A placed thereon is seated on the lifting unit  200 , when the contact members  32 A are positioned on the first step portions A of the driven gears sections  230  as illustrated in  FIG. 15 , the cover  30 A and the cushion  40 A remain in the lowest positions. 
         [0071]    In this position, when the user rotates the handle in one direction as an attempt to raise the height of the pillow, the driving shaft  220  on which the handle  210  is disposed is rotated, so that the bevel gears consisting of the pinion gear  222  and the ring gear  224  rotate responsively. 
         [0072]    Thus, the driving gear section  226  on which the ring gear  224  of the bevel gears is seated is rotated in one direction, so that the plurality of driven gears sections  230  meshed with the driving gear section  226  are also rotated in one direction. That is, since teeth of the driving gear section  226  are meshed with teeth  232  of the driven gears sections  230 , the driven gears sections  230  are rotated along with the rotation of the driving gear section  226 . 
         [0073]    As the driven gears sections  230  are rotated as described above, the lifting portions  234  formed on the top portions of the driven gears sections  230  are also rotated, so that the contact members  32 A are moved along the slopes to be positioned on the next higher step portions, thereby displacing the cover  30 A upwards. 
         [0074]    For example, as illustrated in  FIG. 16 , the driving shaft  220 , the bevel gears, and the driving gear section  226  rotate in response to the rotation of the handle  210 . This leads to the rotation of the driven gears sections  230 , so that the lifting portions  234  are also rotated. When the third steps C are positioned on the bottoms of the contact members  32 A, the cover  30 A and the cushion  40 A are moved upwards to a predetermined height. In this case, the contact members  32 A are seated on the third step portions C after having moved along the first slopes a, the second step portions B, and the second slopes b. 
         [0075]    When the handle  210  is rotated further, as illustrated in  FIG. 17 , the contact members  32 A are seated on the sixth step portions F after having moved along the third slopes c, the fourth step portions D, the fourth slopes d, and the fifth step portions E, and the fifth slopes e, in response to the rotation of the driving shaft  220 , the bevel gears, the driving gear section  226 , and the driven gears sections  230 . 
         [0076]    In the position in which the cover  30 A and the cushion  40 A have been moved to the height positions as described above, when the handle  20 A is rotated further, the contact members  32 A move downwards along the sixth slopes f in response to the rotation of the driving shaft  220 , the bevel gears, the driving gear section  226 , and the driven gears sections  230  to be seated on the first step portions A. Consequently, the cover  30 A and the cushion  40 A are in the lowest positions, as illustrated in  FIG. 15 . 
         [0077]    For reference, the second embodiment of the present invention has described that the heights of the cover  30 A and the cushion  40 A are raised as the contact members  32 A moved from the lowest step portions to the higher step portions of the lifting portions  234  in response to the handle  210  being rotated. Alternatively, the second embodiment of the present invention may be configured such that the heights of the cover  30 A and the cushion  40 A are lowered as the contact members  32 A move from the higher step portions to the lower step portions of the lifting portions  234  in response to the handle  210  being rotated in the opposite direction. 
         [0078]    In addition, each of the lifting portions  234  formed on the top portions of the driven gears sections  230  as illustrated in  FIG. 14  may have projections (not shown) on boundaries between the step portions A to F and the slopes a to f, each of the projections protruding a predetermined height from the corresponding step portion, such that the contact members  32 A cannot move from a higher step portion to a lower step portion of the lifting portion  234  along the slopes a to f of the lifting portion  234  unless external force having a predetermined intensity is applied. 
       Third Embodiment 
       [0079]    A height-adjustable pillow according to a third exemplary embodiment of the present invention is illustrated in  FIGS. 18 to 22 . 
         [0080]    As illustrated in  FIGS. 18 and 19 , the height-adjustable pillow according to the third exemplary embodiment of the present invention includes a base  20 B and a cover  30 B. The base  20 B is a lower member in the shape of a box with at least a portion of the top surface thereof being open. The cover  30 B is an upper member seated on the base  20 B such that the cover  30 B can be displaced linearly up and down. The base  20 B and the cover  30 B form a pillow body. The height-adjustable pillow according to the third exemplary embodiment further includes a lifting unit  300  displacing the cover  30 B up and down with respect to the base  20 B to adjust the height of the cover  30 B. A cushion  40 A is provided on the cover  30  to elastically support the head. Thus, the cushion  40 A is displaced up and down together with and in the same direction as the cover  30 B in response to the operation of the lifting unit  300 . 
         [0081]    As illustrated in  FIGS. 19 and 20 , the lifting unit  300  includes a driving shaft  220  extending through a wall (e.g. a front wall) of the base  20 B. The driving shaft  220  is arranged horizontally to be rotatable. The lifting unit  300  further includes a driving bevel gear  330  disposed on the driving shaft  310  in the inner space of the base  20 B, a driven bevel gear  340  meshed with the driving bevel gear  330 , a driving spur gear  350  disposed coaxially with the driven bevel gear  340 , and a single or plurality of driven spur gears  360  meshed with the driving spur gear  350 . A handle  210  is disposed on the driving shaft  310  outside of the base  20 B. The driving spur gear  350  is disposed on the bottom of the base  20 B. The driven spur gears  360  are provided in a plural number. The driven spur gears  360  are arranged around the driving spur gear  350  and are mounted on the bottom of the base  20 B. The driven bevel gear  340  is disposed on the driving spur gear  350 . 
         [0082]    When the handle  320  is rotated, the driving bevel gear  330  is rotated along with and in the same direction as the driving shaft  310 . The driven bevel gear  340  and the driving spur gear  350  are simultaneously rotated about the axis extending in the vertical direction, and the driven spur gears  360  are also driven about the top-bottom axis. 
         [0083]    The configuration of the height-adjustable pillow according to the third exemplary embodiment as described above is substantially identical or similar to the configuration according to the second embodiment. 
         [0084]    As illustrated in  FIGS. 20 and 21 , the lifting unit  300  further includes rotary members  370  disposed on the driven spur gears  360  to rotate along with the driven spur gears  360 , respectively, and contact members  380  protruding from the cover  30  in the direction of the rotary members  370 . Here, the contact members  380  function similarly to the contact members  32 A according to the second embodiment. 
         [0085]    Each of the rotary members  370  has a slope  372  on the top portion thereof, the slope  372  being upwardly inclined in one direction (i.e. counterclockwise in the drawing) along the circumference about the axis of the underlying driven spur gear  360 . Holding step portions  374  are formed on the slope  372 , continuously along the length of the slope  372 , such that the holding step portions  374  are positioned at different heights. 
         [0086]    The distal end of each of the contact members  380  is in contact with one of the holding step portions  374 , depending on the angle of rotation of the rotary member  370 . 
         [0087]    Each of the holding step portions  374  includes a stepped surface  376  and a connecting surface  378 . In each of the slopes  732 , the stepped surfaces  376  are arranged at predetermined distances along the length of the slope  372  such that the stepped surfaces  376  are spaced apart and positioned at different heights from each other. The connecting surfaces  378  are formed as inclined surfaces connecting the stepped surfaces  376  that are at different heights. With this configuration, when the rotary member  370  is rotated, the contact member  380  is moved up or down while coming into contact with the stepped surfaces from one to an adjacent one. 
         [0088]    The stepped surfaces  376  are inclined downwardly in one direction along the circumference about the axis of the underlying driven spur gear  360  in order to prevent the contact member  380  from being unintentionally moved along with the connecting surfaces  378 . 
         [0089]    Although not specifically illustrated, the height-adjustable pillow according to the third exemplary embodiment of the present invention may include a guide for guiding upward and downward displacement of the cover  30 B. The guide may include one or more guide pins (not shown) protruding downward from the cover  30 B and pin-receiving members  50 B formed on the base  20 B, each of the pin-receiving members  50 B having a guide hole in which the corresponding guide pin is received. Alternatively, the positions of the guide pins may be exchanged with the positions of the pin-receiving members  50 B. Here, the functions of the guide pins and the pin-receiving members  50 B are substantially identical or similar to the functions of the guide pins  34 A and the pin-receiving members  22 A according to the second embodiment. 
         [0090]    The operational relationship of the height-adjustable pillow according to the third exemplary embodiment of the present invention will be described as follows: 
         [0091]    When the contact members  380  are positioned on the stepped surfaces  376  of the holding step portions  374 , the cover  30 B remains in the lowest position. 
         [0092]    In this position, when the handle  320  is rotated counterclockwise in the drawing of  FIG. 20 , the driving bevel gear  330 , the driven bevel gear  340 , the driving spur gear  350 , and the driven spur gears  360  are rotated together with the driving shaft  310 . At the same time, the driven spur gears  360  are rotated clockwise in the drawing of  FIG. 20 . Then, the contact members  380  are moved upwards along the inclined connecting surfaces  378  of the lowest holding step portions  374  to be positioned on the stepped surfaces  376  of the higher step portions next to the lowest holding step portions  374 , so that the cover  30 B is set to a one-step higher height. 
         [0093]    When the handle  320  is rotated continuously in the same direction, the height of the cover  30 B is continuously raised. In contrast, when the handle  320  is rotated in the opposite direction, the contact members  380  are positioned on the stepped surfaces of the lower holding step portions, so that the height of the cover  30 B is lowered. 
         [0094]    Reference numeral  400  in  FIG. 22  indicates an indicating unit that indicates the height of the cover  30 B that has been moved up or down by the lifting unit  300 . 
         [0095]    Referring to  FIGS. 18 and 19  together with  FIG. 22 , the indicating unit  400  includes a rack  410  extending downward from the cover  30 B to be positioned within the base  20 B, a pinion  420  disposed within the base  20 B to be meshed with the rack  410 , an operating gear  430  disposed within the base  20 B to be meshed with the pinion  420 , and an indicating member  440  disposed outside of the base  20 B. The indicating member  440  is mounted on the shaft of the operating gear  430  to rotate along with the operating gear, and has a height indicating portion. Although not illustrated, a pointer may be provided in a portion of the base  20 B adjacent to the indicating portion, such that the pointer represents the height indicated by the indicating portion of the indicating member  440 . 
         [0096]    In the indicating unit  400 , as the cover  30 B is displaced up and down, the rack  410  is moved up and down along with and in the same direction as the cover  30 B, thus rotating the pinion  420  and the operating gear  430 . Consequently, the indicating member  440  is rotated, thereby indicating the height of the cover  30 B that has been displaced up and down. Here, the user can adjust the height of the cover  30 B while visually recognizing the height of the cover  30 B that has been displaced up and down through the height indicating portion. 
         [0097]    Although the present invention has been described for illustrative purposes, the present invention is not limited to the disclosed embodiments and accompanying drawings. Those skilled in the art will appreciate that various modifications are possible without departing from the scope and spirit of the present invention as disclosed in the accompanying claims. In addition, technical concepts described with respect to the embodiments of the present invention may be carried out alone or two or more thereof may be combined.