Bed with a reclining backrest

Abstract

To alleviate abdominal compression and displacement of a patient's body in a leg direction during a back raising operation.SOLUTION: During a back raising operation, a back bottom 2A recedes by a distance M1, and rises by a distance M2. In this case, M1 is in the range of 5-10 cm and M2 is in the range of 5-15 cm, M1 is in the range of 6-10 cm and M2 is in the range of 6-15 cm, M1 is in the range of 7-10 cm and M2 is in the range of 7-15 cm, M1 is in the range of 8-10 cm and M2 is in the range of 8-15 cm, or M1 is in the range of 8-10 cm and M2 is in the range of 12-15 cm.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a bed having a back bottom that can be raised and lowered by the action of a back-raising actuator, and particularly to a technique for retracting and raising the back bottom during the back-raising operation.

Background Art

[0002] This type of conventional device is described in, for example, Patent Document 1 or 2.

[0003] Patent Document 1 discloses a bed configured to move the back bottom obliquely upward in the headboard direction in order to prevent the patient's body from shifting toward the foot side when performing a back-raising operation of raising the back bottom by an actuator.

[0004] Patent Document 2 discloses a bed configured to prevent the patient's body from shifting toward the foot side by moving the back bottom in the head direction while raising the back bottom and raising the knee bottom above the knees.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described in Patent Document 1, moving the back support base diagonally upward and towards the head during back elevation reduces the displacement of the patient's body towards the legs. Furthermore, diagonal movement (especially when knee elevation is performed along with back elevation, as in Patent Document 2) also prevents compression of the patient's abdomen during back elevation. However, these known documents provide no information regarding the appropriate range of movement for the back support base during back elevation for the patient.

[0007] One objective of the present invention is to set the movement conditions of the back base when the back is raised in a bed with a reclining back base to a range appropriate for the patient.

[0008] Other objects of the present invention will become apparent in the following description. [Means for solving the problem]

[0009] In one embodiment, the bed has a back bottom retraction distance of 5-10 cm and an elevation distance of 5-15 cm when the back is raised, more preferably a retraction distance of 6-10 cm and an elevation distance of 6-15 cm, even more preferably a retraction distance of 7-10 cm and an elevation distance of 7-15 cm, even more preferably a retraction distance of 8-10 cm and an elevation distance of 8-15 cm, and even more preferably a retraction distance of 8-10 cm and an elevation distance of 12-15 cm. This appropriately reduces displacement of the patient's body and abdominal compression when the back is raised.

[0010] In one embodiment, the bed has a back base that includes an upper back base and a lower back base, and the upper and lower back bases bend between each other at the back base bending axis, and when the back base is horizontal, the back base bending axis is located within a range of 20 to 42 cm in the head direction from the back base rotation axis.

[0011] This dimensional setting aims to position the flexion axis of the back bottom to correspond to the range from the 7th to the 10th thoracic vertebrae of the patient. This allows the shape of the back bottom to better conform to the kyphosis of the spine for the patient, making it feel more natural.

[0012] In one embodiment of the bed, when the knees are raised, the knee bottom and the foot bottom flex relative to each other at the leg bottom pivot axis, and when the back bottom and the knee bottom are horizontal, the leg bottom flex axis is within a range of 42 to 49 cm in the foot direction from the back bottom pivot axis.

[0013] This dimensional setting aims to position the leg bottom flexion axis directly below the patient's knee joint, or slightly closer to the hip. This allows for a more natural knee lift for the patient. [Brief explanation of the drawing]

[0014] [Figure 1] The images show a side view (A) of a bed according to one embodiment when the back bottom is upright at a predetermined maximum angle, and a side view (B) when the bed is lying horizontally. [Figure 2] This side view clearly shows how the backrest and its pivot axis move during the process of raising the back of the bed. [Figure 3] A simplified side view is shown, illustrating the main components of the mechanism that moves the pivot axis of the backrest bottom when the backrest is raised. [Figure 4] The model used for the theoretical calculation of the backward and upward distances of the back bottom during back elevation is shown. [Figure 5] The results of an evaluation experiment on the backward and upward distances of the back bottom during back elevation are shown. [Figure 6] This shows the preferred position range for the dorsal bottom flexion axis and the leg bottom flexion axis. [Figure 7] A simple model is shown illustrating the standard spinal midline shape and thoracic spine alignment when a patient is seated with their upper body naturally upright. [Modes for carrying out the invention]

[0015] Figure 1 shows a side view (A) of a bed according to one embodiment when the back bottom is at its highest angle and upright, and a side view (B) when the bed is lying horizontally.

[0016] As shown in FIG. 1, the bed 1 has a bottom 2, and the bottom 2 is mounted on an elevating frame 3 that can be raised and lowered. Usually, a mattress is laid on the bottom 2, and a patient lies horizontally thereon. The bottom 2 has a back bottom 2A that supports the upper body of the patient, a waist bottom 2B that supports the buttocks (waist) of the patient, a knee bottom 2C that supports the thighs of the patient, and a foot bottom 2D that supports the lower legs and feet of the patient. The sub-bottoms 2A to 2D thereof can be driven by one or more electric actuators to move so as to bend relative to each other. Hereinafter, the knee bottom 2C and the foot bottom 2D are collectively referred to as the "leg bottom".

[0017] The back bottom 2A can be raised and lowered by rotating about the back bottom rotation axis 5. The raising motion of the back bottom 2A is achieved by an upward pushing force applied to the back bottom 2A from an electric actuator 7 supported by the elevating frame 3 via a back-lifting link 9. The back bottom rotation axis 5 is configured to move along with the back-lifting by a back bottom movement mechanism 11 attached to the elevating frame 3.

[0018] In the process of lifting the back bottom 2A from the horizontally lying posture shown in FIG. 1(B) to the standing posture at the maximum angle (for example, 70 degrees with respect to the horizontal) shown in FIG. 1(A), the back bottom 2A and the back bottom rotation axis 5 move in a diagonal direction that is the head direction (the back direction for the patient when the back bottom is raised) (left direction in the figure) and the upward direction for the patient due to the action of the back bottom movement mechanism 11. Hereinafter, the movement of the back bottom 2A in the head (or back) direction at this time is referred to as "retreat", and the upward movement is referred to as "rise". The retreat distance M1 and the rise distance M2 of the back bottom 2A are set within a preferable range as described later.

[0019] The back bottom 2A has an upper back bottom 2E that supports the portion from approximately the upper half of the thoracic vertebra column to the head within the upper body, and a lower back bottom 2F that supports the portion from approximately the lower half of the thoracic vertebra column to the lumbar vertebra column within the upper body. The upper and lower back bottoms 2E and 2F are connected to each other so as to be foldable via the back bottom bending axis 13. Due to the action of the electric actuator 12, the upper back bottom 2E rotates around the back bottom bending axis 13 with respect to the lower back bottom 2F, enabling the patient to bend forward.

[0020] The lumbar bottom 2B is fixed at a fixed position on the lifting frame 3 and does not move or tilt. The knee bottom 2C rotates around the knee bottom rotation axis 14 due to the action of an electric actuator (not shown), and can be raised and lowered within a range from the horizontally lying position shown in FIG. 1 to the maximum angle (for example, 30 degrees with respect to the horizontal), thereby raising and lowering the patient's knees. The foot bottom 2D is connected to the knee bottom 2C via the leg bottom bending axis 15. When the knee bottom 2C stands up, the foot bottom 2D rotates and bends around the leg bottom bending axis 15 with respect to the knee bottom 2C.

[0021] The lifting frame 3 that supports the bottom 2 is mounted on a lifting mechanism 16 for raising and lowering the lifting frame 3. The lifting mechanism 16 is mounted on a base frame 17 placed on the building floor.

[0022] FIG. 2 shows a side view that clearly shows how the back bottom rotation axis 5 moves during the process of raising the back of the bed 1.

[0023] In FIG. 2, reference numerals 2A-0 to 2A-7 indicate the postures of the back bottom 2A at intervals of 10 degrees of the standing angle from the initial horizontally lying start to the final standing at the maximum angle of, for example, 70 degrees during the back raising process. Reference numerals 5-0 to 5-7 indicate the positions of the back bottom rotation axis 5 corresponding to the different postures 2A-0 to 2A-7 of the back bottom 2A. As shown here, during the back raising process, the back bottom rotation axis 5 continuously retreats and rises from the start to the end.

[0024] Figure 3 shows a simplified side view of the main parts of the back bottom movement mechanism 11.

[0025] The back bottom movement mechanism 11 has a pair of left and right link mechanisms provided on the left and right main beams 3A that extend in the longitudinal direction of the bed of the lifting frame 3. As shown in Figure 3, the link mechanisms on each side of the back bottom movement mechanism 11 have a first link 18 and a second link 19 that are combined in an inverted V shape. The first link 18 and the second link 19 are rotatably connected to each other by the back bottom pivot shaft 5.

[0026] The first link 18 is fixed at its upper end to the lower end of the back bottom 2A (lower back bottom 2F). The first link 18 has a roller mechanism 20 at its lower end. The roller mechanism 20 is movable along a guide rail 21 fixed to the main girder 3A of the lifting frame 3 in the longitudinal direction of the bed and in a direction 29 that is slightly angled from the horizontal. The back bottom pivot shaft 5 is provided at a fixed position near the lower end of the back bottom 2A on the first link 18.

[0027] The second link 19 is rotatably axially connected to the first link 18 at its upper end via the back bottom pivot shaft 5, as described above. At its lower end, the second link 19 is rotatably axially connected to the main girder 3A, which is located at a fixed position on the main girder 3A of the lifting frame 3, around a pivot shaft 23.

[0028] During back elevation, the back bottom 2A is pushed in the direction of arrow 25 shown in Figure 3 by the action of the back elevation actuator 7 and back elevation link 9 shown in Figure 1. As a result, the roller mechanism 20 of the first link 18 moves along the guide rail 21 in the direction of arrow 29, and at the same time, the first link 18 stands upright in the direction of arrow 27. Consequently, the second link 19 stands upright around the pivot axis 23 in the direction of arrow 31.

[0029] As a result, the back bottom pivot axis 5 moves backward and upward in the direction of arrow 33, and at the same time, the back bottom 2A rotates around the backward and upward moving back bottom pivot axis 5 and stands upright. In other words, the back bottom 2A stands upright while moving backward and upward.

[0030] Figure 4 shows the model used for the theoretical calculation of the backward distance M1 and upward distance M2 of the back bottom 2A when the backrest is raised.

[0031] The model shown in Figure 4 illustrates that the ideal state is one in which the positional relationship between the patient's upper and lower body and the bottom 2 (i.e., the position of the greater trochanter 47) is maintained (i.e., the bottom 2 does not unnaturally shift the patient's body) when the back bottom 2A of bed 1 is laid horizontally (dashed line), and the leg bottoms 2C and 2D are also laid horizontally and flat, and a mattress 41 is placed on top of them, with the patient 43 lying on their side (upper body in the position shown by the dashed line), and the back bottom 2A is raised to its maximum angle, for example, 70 degrees.

[0032] As shown in Figure 4, with the back bottom 2A tilted horizontally (dashed line), the patient's body is positioned relative to the bottom 2 as follows: The anterior superior iliac spine (the most anteriorly protruding part of the pelvis) (hereinafter abbreviated as "ASIS") 45 of the patient's pelvis is positioned directly above the flexion point between the back bottom 2A and the lumbar bottom 2B, that is, the back bottom rotation axis 5.

[0033] This alignment method using ASIS45 is rational in the following two respects. Firstly, the main center of rotation of the patient's body when the patient 43 raises their upper body is roughly the position corresponding to the greater trochanter 47. According to this alignment method, the greater trochanter 47 rests on the lumbar bottom 2B, that is, the patient's buttocks rest on the lumbar bottom 2B, so the posture of the patient 43 when the back or knees of the bottom 2 are raised is less likely to be unnatural. Secondly, the position of ASIS45 can be easily determined by touching the patient 43's body, so it is easy for the caregiver to align ASIS45 with the back bottom rotation axis 5 of the bottom 2. With such alignment, the positional relationship between the patient 43 and the back bottom 2 is always in accordance with the dimensional design of the bottom 2.

[0034] Now, when raising the back of patient 43 from a position where the upper body is lying horizontally (dashed line), the patient's pelvis will stand upright, almost centered on the greater trochanter 47, and the upper body resting on the pelvis will rise. In this process, in order to maintain the positional relationship between patient 43's upper and lower body and bottom 2 (to prevent patient 43's body from shifting position relative to bottom 2), the back bottom 2A needs to rise and move backward in conjunction with the rise of patient 43's upper body.

[0035] The reason why the back base 3A needs to retract is that as patient 43 stands upright, the thickness of patient 43's body and the thickness of the mattress 41, which were previously located below the skeletal line from patient 43's spine to pelvis, move behind patient 43's skeletal line, and therefore the back base 2A needs to retract to accommodate these thicknesses.

[0036] When the back bottom 2A is in an upright position at its maximum angle, e.g., 70 degrees (solid line), the back bottom 2A and the back bottom rotation axis 5 move backward by an ideal distance M1 and rise by an ideal distance M2 from their initial positions, the relative positions of the back bottom 2 and the patient's body 43 (e.g., the positional relationship between the lumbar bottom 2B and the greater trochanter 47, and the positional relationship between the back bottom flexion axis 13 and a specific thoracic vertebra (e.g., the 7th thoracic vertebra) 49 of the patient 43) remain unchanged. The above-mentioned ideal backward distance M1 and upward distance M2 will vary depending on the patient's physique and the thickness of the mattress 41.

[0037] Therefore, based on the physique of a Japanese adult woman in the 5th percentile, as described in the publicly available document "Databook of Human Body Dimensions of Japanese People 2004-2006, published by the Human Life Engineering Research Center," the ideal retraction distance M1 and rise distance M2 shown in Figure 4 were set. The reason for using the physique of a woman in the 5th percentile is as follows: Generally, to suppress slippage toward the feet, it is easier to suppress slippage if the knee bottom flexion position is shorter than the actual knee flexion position of the person. Therefore, it was judged that adult women in the 5th percentile are more susceptible to the effects of positional slippage between the bottom 2 and the body. For this reason, it was thought that designing the bed with such people in mind would lead to improved comfort for more people (fewer people would be negatively affected). The thickness of the mattress 41 was set at 6 cm after examining various mattresses and taking into account the amount of sinking of the mattress 41 when a person lies on it.

[0038] As a result, the ideal movement conditions for the back bottom 2A during back elevation were found to be a backward distance M1 of approximately 8 cm and an upward distance M2 of approximately 12 cm. Taking into account individuals with larger physiques, the ideal movement conditions were determined to be a backward distance M1 of approximately 8-10 cm and an upward distance M2 of approximately 12-15 cm.

[0039] In reality, even if the travel distance is somewhat shorter than the ideal travel conditions described above, it is considered to be tolerable to a degree that does not pose a practical problem due to various factors such as the flexibility of the mattress 41 and clothing, as well as the tolerance and insensitivity of the human body and senses. Therefore, we experimentally evaluated what distances of backward movement M1 and upward movement M2 are necessary for a real person to not feel discomfort when raising their back.

[0040] This evaluation experiment involved 30 male and female subjects ranging in height from 161cm to 184cm. Each subject experienced back elevation on a simulated bed with different backward movement distances (M1) and upward movement distances (M2) at the point of maximum back elevation (maximum back bottom angle of 70 degrees). The presence or absence of discomfort or unease during back elevation was investigated.

[0041] Figure 5 shows the results of this evaluation experiment.

[0042] Figure 5 shows the percentage of all subjects who felt discomfort for several movement conditions (indicated by black circles) that combine different backward distances M1 and upward distances M2. According to this, under the condition M1=5cm and M2=5cm, only 10% of subjects felt discomfort, meaning 90% did not, which is considered to be within a practically acceptable range. As M1 and M2 increase, the percentage of people who felt discomfort decreases further, reaching zero at M1=8cm and M2=8cm. Furthermore, even when approaching the ideal condition with M1=8cm and M2=12cm, the percentage of people who felt discomfort was still zero. However, several subjects felt that the condition closer to the ideal felt more natural compared to M1=8cm and M2=8cm.

[0043] Considering the experimental results above and the ideal movement conditions described above, one of the preferable movement conditions is M1 = 5-10 cm and M2 = 5-15 cm. A more preferable movement condition is M1 = 6-10 cm and M2 = 6-15 cm, even more preferable is M1 = 7-10 cm and M2 = 7-15 cm, and even more preferable is M1 = 8-10 cm and M2 = 8-15 cm. And an even more preferable movement condition is the ideal condition obtained from the above calculations: M1 = 8-10 cm and M2 = 12-15 cm.

[0044] As described above, the preferred range of movement conditions for the back bottom 2A when the backrest is raised has been clarified. In addition, the inventors also considered preferred positional and dimensional conditions for other parts of the bottom 2.

[0045] First, regarding the preferred position of the dorsal bottom flexion axis 13, that is, the flexion point between the upper dorsal bottom 2E and the lower dorsal bottom 2F, the following conditions are preferable. That is, when the dorsal bottom 2A is horizontal, the position of the dorsal bottom flexion axis 13 is preferably within the range from the position directly below the 10th thoracic vertebra 51 of patient 43 shown in Figure 6(A) to the position directly below the 7th thoracic vertebra 49 shown in Figure 6(B). The reason for this is as follows.

[0046] Figure 7(A) shows a simplified model of the lateral view shape of the standard spinal midline 55 and the arrangement of the 1st to 12th thoracic vertebrae when patient 43 is seated with his upper body naturally upright. As shown here, patient 43's back is naturally slightly curved backward, and (although there are individual differences, typically) the position of the 7th thoracic vertebra 49 is the most posteriorly protruding. Therefore, to adapt the shape of the back bottom 2A to this natural posterior kyphosis, it is preferable that the back bottom flexion axis 13 is positioned directly below the 7th thoracic vertebra 49 when the back bottom 2A is horizontal, as shown in Figure 6(B).

[0047] Figure 7(B) shows a simplified model of the standard lateral view shape of the spinal midline 55 and the arrangement of the 1st to 12th thoracic vertebrae when patient 43 is sitting with their upper body slightly bent forward for reading or eating. As shown here, patient 43's back is more curved than in Figure 7(A), and (although there are individual differences, typically) this curvature is the natural kyphosis of the spinal line 55 plus the curvature of the lower thoracic vertebrae centered on the 10th thoracic vertebra 51 (which is the most easily curved). When patient 43 bends forward even more than in Figure 7(B), the curvature of the 10th thoracic vertebra 51 becomes even more pronounced. Therefore, in order to adapt the shape of the back bottom 2A to a bent-over posture, as shown in Figure 6(A), when the back bottom 2A is horizontal, it is preferable that the back bottom flexion axis 13 is located directly below the 10th thoracic vertebra 51 or directly below the range from the 10th thoracic vertebra 51 to the 7th thoracic vertebra 49.

[0048] Therefore, as shown in Figure 6, when the back bottom 2A is horizontal, it is preferable that the back bottom flexion axis 13 is located directly below the range from the 10th thoracic vertebra 51 to the 7th thoracic vertebra 49 of the patient 43. The extent of this positional range varies depending on the patient's physique. The inventors set the dimensions considering the physiques of Japanese women from the 5th percentile to the 95th percentile of men, as mentioned above. As a result, it was found that when the back bottom 2A is lying horizontally, the distance L1 from the position of the back bottom rotation axis 5 (i.e., directly below the patient's ASIS 45) to the back bottom flexion axis 13 is approximately 20 to 42 cm, which is the condition for it to be located directly below the range from the 10th thoracic vertebra 51 to the 7th thoracic vertebra 49.

[0049] Furthermore, the range of approximately 20-42 cm for the distance L1 mentioned above is also valid for people with a larger physique than those used in the calculation above. This is because the position of the 10th thoracic vertebra (51) is relatively close to the ASIS, so even in people with a larger physique, there is not much difference compared to those with the target physique. Therefore, the position of L1=20 cm mentioned above effectively corresponds to the 10th thoracic vertebra even in people with a larger physique. Also, the position of the 7th thoracic vertebra is shifted further from the ASIS in people with a larger physique than in those with the target physique, but the position of L1=42 cm mentioned above corresponds to the position between the 7th and 10th thoracic vertebrae in people with a larger physique.

[0050] Figure 6(B) further shows the preferred position of the leg bottom flexion axis 15. Specifically, with the back bottom 2 lying horizontally, the distance L2 from the position of the back bottom rotation axis 5 (i.e., the position corresponding to the patient's ASIS 45) to the leg bottom flexion axis 15 is preferably 42-49 cm. This distance L2 was calculated based on the aforementioned physique of Japanese women in the 5th percentile, and the judgment that it is preferable for the distance from the ASIS 45 to the knee joint 53 to be the same as or slightly shorter than that. The reason for including the condition that the distance L2 to the leg bottom flexion axis 15 be slightly shorter than the distance to the knee joint 53 is that, as a result of actually performing knee lifting of the knee bottom 2C, the knee lift felt more natural to the patient 43 when the leg bottom flexion axis 15 was located directly below a point slightly towards the waist from the knee joint 53, rather than when it was located directly below the knee joint 53. Furthermore, even for people with a larger physique than the one used in the calculation, the preferred distance L2 = 42-49 cm is still preferable because it lies closer to the waist than the knee joint (53).

[0051] The embodiments described above are merely illustrative examples for illustrative purposes and are not intended to limit the scope of the present invention to those embodiments only. The present invention can be implemented in various forms different from those described above. [Explanation of Symbols]

[0052] 1: Bed, 2: Bottom, 2A: Back bottom, 2B: Waist bottom, 2C: Knee bottom, 2D: Foot bottom, 2E: Upper back bottom, 2F: Lower back bottom, 3: Lifting frame, 3A: Main beam of lifting frame, 5: Back bottom rotation axis, 11: Back bottom movement mechanism, 13: Back bottom bending axis, 15: Leg bottom bending axis, 18: First link of back bottom movement mechanism, 19: Second link of back bottom movement mechanism, 21: Back bottom movement mechanism Guide rail, 43: patient, 45: patient's anterior superior iliac spine (ASIS), 47: patient's greater trochanter, 19: patient's 7th thoracic vertebra, 21: patient's 10th thoracic vertebra, 53: patient's knee joint, M1: backward movement distance of the back bottom when the back is raised, M2: upward movement distance of the back bottom when the back is raised, L1: distance from the back bottom rotation axis to the back bottom flexion axis when the back bottom is horizontal, L2: distance from the back bottom rotation axis to the leg bottom flexion axis when the back bottom is horizontal.

Claims

1. In a bed with a standable back base, The aforementioned back bottom has an upper back bottom located on the user's head side and a lower back bottom provided between the upper back bottom and the waist bottom. The aforementioned back bottom is rotatable around a back bottom pivot axis provided at the lower end of the lower back bottom, During the back-raising process, in which the back bottom is raised from horizontal to the maximum angle around the back bottom pivot axis, the back bottom is configured to retract and rise together with the back bottom pivot axis. The retraction distance M1 and the upward movement distance M2 of the back bottom during the back-raising process are in the following range groups: M1 = 5-10 cm and M2 = 5-15 cm, M1 = 6-10 cm and M2 = 6-15 cm, M1 = 7-10 cm and M2 = 7-15 cm, M1 = 8-10 cm and M2 = 8-15 cm, M1 = 8-10 cm and M2 = 12-15 cm A bed located within one of the selected areas.

2. In the bed according to claim 1, It has a frame that supports the back bottom and the waist bottom, A bed further comprising a back bottom moving mechanism between the back bottom pivot shaft and the frame, which allows the back bottom and the back bottom pivot shaft to move back and up together relative to the frame.

3. In the bed described in claim 2, The aforementioned back bottom movement mechanism has a first link and a second link, One end of the first link and one end of the second link are rotatably connected to each other via the back bottom pivot axis. A bed in which the other end of the first link is slidably mounted along the frame, and the other end of the second link is rotatably fixed to the frame.

4. In the bed according to claim 1, The upper back bottom is configured to bend forward relative to the lower back bottom at a back bottom bending axis located between them. A bed in which, when the back bottom is horizontal, the distance L1 from the back bottom rotation axis to the back bottom bending axis is within the range of 20 to 42 cm.

5. In the bed according to claim 1, The upper back bottom is configured to bend forward relative to the lower back bottom at a back bottom bending axis located between them. A bed configured such that when the patient lies on the base with the base horizontal and the patient is positioned on the base such that the pivot axis of the base is located directly below the patient's anterior superior iliac spine, the flexion axis of the base is located directly below the patient's thoracic vertebrae from the 10th to the 7th thoracic vertebrae.

6. In the bed according to claim 2 or 3, The frame has a knee bottom that allows the knee to be raised, and a leg bottom that includes a foot bottom, When the knee is raised, the knee is configured to flex relative to the foot at a leg bottom flexion axis provided between them. A bed in which, when the back bottom and the leg bottom are horizontal, the distance L2 from the pivot axis of the back bottom to the bending axis of the leg bottom is in the range of 42 to 49 cm.

7. In the bed according to claim 2 or 3, The frame has a knee bottom that allows the knee to be raised, and a leg bottom that includes a foot bottom, When the knee is raised, the knee is configured to flex relative to the foot at a leg bottom flexion axis provided between them. When the patient lies on the base with the back base and leg base horizontal, and the patient is positioned on the back base such that the pivot axis of the back base is located directly below the patient's anterior superior iliac spine, A bed in which, when the back bottom and the knee bottom are horizontal, the leg bottom flexion axis is located directly below the patient's knee joint, or directly below a point closer to the waist than the knee joint.

Images