mattress

Abstract

To provide a mattress capable of suppressing facial problems caused by aging and having a simple structure. [Solution] The mattress 1 has a recess 24 in which a part of the back of the head BH of a human HU sleeping on his back comes into contact with the mattress 1. The recess 24 is configured so that the tip CH1 of the chin CH of the human HU sleeping on his back is positioned higher than the forehead FH. The mattress 1 is integrally formed.

Description

[Technical field]

[0001] The present invention relates to a mattress. [Background technology]

[0002] In recent years, various mattress shapes have been proposed. For example, Patent Document 1 proposes a mattress composed of multiple parts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-184227 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the mattress disclosed in Patent Document 1 leaves room for improvement in terms of preventing facial problems that occur with aging.

[0005] Therefore, the present invention has been made in consideration of the above circumstances, and has an object to provide a mattress that can suppress facial problems caused by aging and has a simple structure. [Means for solving the problem]

[0006] In order to solve the above problems, the mattress according to the present invention has a recess in a portion that comes into contact with at least the back of the head of a person sleeping on his / her back, into which a part of the back of the head fits, and the recess is configured so that the tip of the chin of a person sleeping on his / her back is positioned higher than the forehead. The recess includes a recess body formed in a truncated cone shape and an extension portion that is connected to the recess body and extends along the width direction. The recess body has a bottom surface located downward in the vertical direction and a recess side surface that rises obliquely from the bottom surface in the vertical direction. The bottom surface is inclined so that the bottom is deeper at the end side close to the head in the vertical direction and the bottom is shallower at the end side close to the legs, and is the portion on which the back of the head of a person sleeping on his / her back is placed. . Effect of the Invention

[0008] According to the mattress of the present invention, since it has the above-mentioned configuration, it is possible to provide a mattress with a simple configuration that can suppress facial problems caused by aging. [Brief description of the drawings]

[0009] The drawings show specific embodiments of the invention according to the present disclosure, including essential features of the invention as well as alternative and preferred embodiments. [Figure 1] FIG. 1 is a perspective view of a mattress according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the mattress shown in FIG. 1 in use. [Diagram 3] FIG. 3 is an enlarged cross-sectional view of a part of FIG. [Figure 4] FIG. 4 is a perspective view of a mattress according to the second embodiment. [Diagram 5] FIG. 5 is a cross-sectional view showing the mattress shown in FIG. 4 in use. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a portion of FIG. [Figure 7] FIG. 7 is a perspective view of a mattress according to a third embodiment, showing a state in which the first portion of the mattress shown in FIG. 4 has been changed to a spare first portion. [Figure 8] FIG. 8 is a perspective view of a mattress according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Embodiment] The following describes in detail the form (embodiment) for carrying out the present invention with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. The components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0011] [First embodiment] The mattress 1 according to this embodiment is, for example, a mattress 1 used as bedding. Hereinafter, the mattress 1 according to this embodiment will be described with reference to Figs. 1 to 3.

[0012] Fig. 1 is a perspective view of a mattress 1 according to a first embodiment. Fig. 2 is a cross-sectional view showing the mattress 1 shown in Fig. 1 in use. Fig. 3 is an enlarged cross-sectional view of a portion of Fig. 2. When the mattress 1 shown in Figs. 1 to 3 is in use, a sheet is used to cover at least the upper surface of the mattress 1 in the up-down direction H, but for ease of explanation, the sheet is omitted from the mattress 1 shown in Figs. 1 to 3.

[0013] The mattress 1 according to this embodiment includes a main body 11 and a fitting member 12. The main body 11 is integrally formed in a generally rectangular parallelepiped shape having a first flat surface 11F at an upper side U in the vertical direction H that is large enough for an adult human to lie down on.

[0014] The main body 11 will be described in more detail. As shown in FIG. 1, the main body 11 has a first portion 2, a second portion 3, and a third portion 4. As shown in FIG. 2, the first portion 2 is a portion on which the head (more specifically, the back of the head BH) of the human HU lying on his / her back is mainly placed. The second portion 3 is a portion on which the trunk TR of the human HU lying on his / her back is mainly placed. The third portion 4 is a portion on which the legs LE of the human HU lying on his / her back are mainly placed. In the main body 11 according to this embodiment, the first portion 2, the second portion 3, and the third portion 4 are integrally formed as shown in FIG. 1 and FIG. 2.

[0015] The main body 11 and the fitting member 12 are formed of a material that contains an elastic material, and is deformed when an object is placed on the upper side U in the vertical direction H.

[0016] As shown in Fig. 1, the mattress 1 according to this embodiment has a vertical direction L, a vertical direction H, and a width direction W. The vertical direction L is the longitudinal direction of the mattress 1, and is the direction in which the body of a lying person HU extends. The vertical direction H is the thickness direction of the mattress 1. The width direction W is the short side direction of the mattress 1. The vertical direction L, the vertical direction H, and the width direction W are mutually perpendicular. The vertical direction H includes an upward direction U, which is one side of the vertical direction H, and a downward direction D, which is the other side of the vertical direction H.

[0017] The main body 11 has a recess 24, and a first flat surface 11F is provided on the entire upper surface except for the recess 24. The first flat surface 11F is formed as a flat surface that extends along the horizontal direction without being inclined.

[0018] However, the mattress 1 described in the above-mentioned Patent Document 1 has the following problems. Specifically, the problems with the mattress 1 described in Patent Document 1 are described below.

[0019] When people look at each other's faces, they can sense the other person's approximate age because time leaves its mark on the face. Aging causes facial muscles to sag and fine wrinkles to appear on the face, making the other person feel their age. We know that the Earth's gravity G affects the human HU throughout its life. The face is also constantly affected by gravity G, and as we age, collagen in the skin is gradually lost, the skin sags, and muscles decrease. As a result, gravity G causes sagging and fine wrinkles under the eyes, deepening nasolabial folds, and drooping around the mouth, imprinting age on the face.

[0020] During the day, the human HU is always standing or sitting in a chair or the like, so gravity G is always acting downward on the face. And, since the upper end surface of the mattress 1 described in Patent Document 1 is formed as a flat surface along the horizontal plane, gravity G is always acting directly downward on the face, or gravity G is still acting obliquely downward from the head to the legs LE, even during sleep at night.

[0021] As a result, gravity G constantly applies force to the face either directly downward in the vertical direction H or toward the legs LE, and over time, the facial skin becomes saggy, and aging problems such as fine wrinkles appear on the face occur due to gravity G.

[0022] The mattress 1 according to this embodiment has the following configuration, and is therefore capable of suppressing the above-mentioned problems associated with aging.

[0023] The first portion 2 of the mattress 1 according to this embodiment has a recess 24. The recess 24 is located in a portion that comes into contact with at least the back of the head BH of a person HU sleeping on his / her back, and is a portion into which a part of the back of the head BH fits.

[0024] The recess 24 includes a recess main body 241 formed in a truncated cone shape, and an extension portion 242 extending along the width direction W. The recess main body 241 has a bottom surface 2411 on the lower side D in the vertical direction H, and is formed in a truncated cone shape such that the area of ​​the bottom surface 2411 is smaller than the area of ​​a virtual upper surface 2412 on the upper side U in the vertical direction H.

[0025] The recess body 241 has, for example, a bottom surface 2411 located on the other side D of the vertical direction H in the recess 24, and a recess side surface 2413 rising obliquely in the vertical direction H from the bottom surface 2411.

[0026] More specifically, the bottom surface 2411 is inclined in the longitudinal direction L so that the end portion close to the head is deeper and the end portion close to the leg portion LE is shallower.

[0027] The bottom surface 2411 is a portion on which (contacts) the back of the head BH of the human HU sleeping on his / her back is placed. The recess side surface 2413 is a portion that faces (contacts) the side of the head of the human HU sleeping on his / her back. The recess 24 is provided in a portion of the first part 2 that contacts at least the back of the head BH of the human HU sleeping on his / her back. A part of the back of the head BH of the human HU sleeping on his / her back fits into the recess 24. The recess 24 is configured so that the tip CH1 of the chin CH of the human HU sleeping on his / her back is located above the forehead FH.

[0028] As described above, the mattress 1 according to this embodiment has a recess 24 in which a part of the back of the head BH of the human HU lying on his / her back is fitted at a portion where the back of the head BH of the human HU lying on his / her back comes into contact, and the recess 24 is configured so that the tip CH1 of the chin CH of the human HU lying on his / her back is located above the forehead FH. Therefore, when the human HU lies on his / her back on the mattress 1 according to this embodiment, the direction of the force applied to the skin and muscles of the face changes (more specifically, the force F1 in the diagonal downward direction from the legs LE to the top of the head TH due to gravity G can be applied to the face). As a result, when the human HU lies on his / her back on the mattress 1 according to this embodiment, as shown in FIG. 3, the force F1 in the diagonal downward direction from the legs LE to the top of the head TH due to gravity G can be applied to the face, thereby suppressing the occurrence of sagging of the facial muscles and suppressing the occurrence of fine wrinkles on the face. Therefore, the mattress 1 according to this embodiment can suppress facial problems caused by aging. In addition, in mattress 1 according to this embodiment, since main body 11 only has recess 24, the structure can be simplified.

[0029] If one lies down on the mattress 1 according to this embodiment for 3 to 4 hours every night, a force F1 can be applied to the face in a diagonally downward direction from the legs LE to the top of the head TH for 3 to 4 hours. Therefore, the mattress 1 according to this embodiment can prevent sagging of the facial muscles and prevent fine wrinkles from appearing on the face.

[0030] In addition, the mattress 1 according to this embodiment has a recess 24 in the area where the neck and the back of the head BH come into contact when sleeping on the mattress 1 in a back-facing position, creating a light back-facing position. As a result, when a person HU is sleeping on his / her back on the mattress 1 according to this embodiment, a diagonally downward force F1 is generated on the face from the legs LE toward the top of the head TH, thereby suppressing aging.

[0031] Furthermore, in the mattress 1 according to this embodiment, since the recess 24 is provided, a force F1 can be applied to the neck of the human HU in a diagonally downward direction from the legs LE to the top of the head TH due to gravity G. Therefore, according to the mattress 1 according to this embodiment, when the human HU sleeps on his / her back, a lightly back-suspension state can be created at the portion where the neck and the back of the head BH come into contact. As a result, when the human HU sleeps on the mattress 1, the cervical vertebrae can be stretched by applying a force F1 in a diagonally downward direction from the legs LE to the top of the head TH to the neck. Therefore, according to the mattress 1 according to this embodiment, an appropriate force can be applied to the human HU with a small amount of neck movement, such as the human HU who sits in a chair for a long time and operates a computer.

[0032] Moreover, the mattress 1 according to this embodiment is formed with a recess 24 into which a part of the head and a part of the neck of the person HU fit. Therefore, the mattress 1 according to this embodiment can generate a diagonally downward force F1 from the leg parts LE toward the top of the head TH on the face for a long period of time, thereby further suppressing aging.

[0033] The bottom surface 2411 is inclined in the vertical direction L so that the end portion close to the head is deeper and the end portion close to the leg LE is shallower. This configuration ensures that a force F1 can be applied to the face in a diagonally downward direction from the leg LE to the top of the head TH, as shown in FIG.

[0034] The mattress 1 according to this embodiment includes an insert member 12 in consideration of the human HU, whose face and neck are subjected to inappropriate force due to gravity G.

[0035] The fitting member 12 is fitted into the recess 24. The fitting member 12 has a second flat surface 12F1 on one side (upper side U) in the vertical direction H, and a fitting member curved surface 12F2 on the other side (lower side D) in the vertical direction, which contacts the recess curved surface 24F that forms the recess 24.

[0036] The fitting member 12 includes a member body 121 formed in a truncated cone shape and an extension portion 122 extending along the width direction W. The member body 121 has a bottom surface 1211 on the lower side D in the vertical direction H, and is formed in a truncated cone shape in which the area of ​​the bottom surface 1211 is smaller than the area of ​​a second flat surface 12F1 on the upper side U in the vertical direction.

[0037] With the fitting member 12 fitted into the recess 24, the recess curved surface 24F of the main body 11 and the member curved surface 12F2 of the fitting member 12 come into contact, and the first flat surface 11F of the main body 11 and the second flat surface 12F1 of the fitting member 12 form a flat surface over the entire upper side U in the vertical direction H of the mattress 1. In other words, with the fitting member 12 fitted into the recess 24, the entire mattress 1 can be returned to a flat surface having a flat surface.

[0038] The mattress 1 according to this embodiment has a recess 24, and includes a main body 11 having a flat first flat surface 11F, and an insertion member 12 to be inserted into the recess 24. The insertion member 12 has a second flat surface 12F1 on one side (upper U) in the vertical direction H, and an insertion member curved surface 12F2 on the other side (lower D) in the vertical direction H that contacts the recess curved surface 24F that forms the recess 24. When the insertion member 12 is inserted into the recess 24, the first flat surface 11F of the main body 11 and the second flat surface 12F1 of the insertion member 12 form a flat surface over the entire upper U in the vertical direction H of the main body 11 and the insertion member 12.

[0039] The mattress 1 of this embodiment includes a second portion 3 on which the torso TR of the human HU sleeping on his / her back rests, and a third portion 4 on which the legs LE of the human HU sleeping on his / her back rests, so that the sleeping human HU can be prevented from sliding down to the end of the mattress 1 closest to the head in the longitudinal direction H.

[0040] The mattress 1 according to the embodiment described above is described as including the main body 11 and the fitting member 12. However, the mattress 1 according to this embodiment may be configured with only the main body 11.

[0041] [Second embodiment] Next, a mattress 1A according to a second embodiment will be described with reference to Figures 4 to 6. In addition, in the configuration of the mattress 1A according to the second embodiment, the same components as those in the mattress 1 according to the first embodiment are given the same reference numerals and the description thereof will be omitted.

[0042] Fig. 4 is a perspective view of a mattress 1A according to a second embodiment. Fig. 5 is a cross-sectional view showing a state in which the mattress 1A shown in Fig. 4 is in use. Fig. 6 is an enlarged cross-sectional view of a portion of Fig. 5.

[0043] As shown in Figs. 4 and 5, a mattress 1A according to this embodiment is formed with a first portion 2A, a second portion 3A, and a third portion 4A, which are formed separately.

[0044] Each of the first portion 2A, the second portion 3A, and the third portion 4A is formed of a material that contains an elastic material and that deforms when an object is placed on the upper side U in the vertical direction H.

[0045] In the mattress 1A according to this embodiment, the length 2H in the longitudinal direction L of the first portion 2A is shorter than the length 3H in the longitudinal direction L of the second portion 3A, as shown in Fig. 5. Furthermore, in the mattress 1A according to this embodiment, the length 2H in the longitudinal direction L of the first portion 2A is shorter than the length 4H in the longitudinal direction L of the third portion 4A.

[0046] An upper end surface 3F is formed on an upper side U of the second portion 3A in the up-down direction H. The upper end surface 3F is formed flat and extends horizontally without being inclined.

[0047] An upper end surface 4F is formed on an upper side U of the third portion 4A in the up-down direction H. The upper end surface 4F is formed flat and extends horizontally without being inclined.

[0048] In the vertical direction H, the height of the upper end surface 3F of the second portion 3A and the height of the upper end surface 4F of the third portion 4A are the same, and in the longitudinal direction L, no step is formed between the second portion 3A and the third portion 4A.

[0049] The first portion 2A has a first end 21 adjacent to the second portion 3A in the longitudinal direction L, and a second end 22 located on the opposite side of the first end 21 in the longitudinal direction L.

[0050] A first connecting means 61 is disposed between the first portion 2A and the second portion 3A. To explain the first connecting means 61 in detail, it is a mechanical fastener means consisting of a hook element 611 and a loop element 612, and for example, the loop element 612 is fixed to the first portion 2, and the hook element 611 is fixed to the second portion 3. To explain the mechanical fastener means in more detail, the mechanical fastener means has a fastener portion (loop element 612) located on the surface side exposed to the side surface of the first portion 2A, and a receiving portion (hook element 611) located on the surface side exposed to the side surface of the second portion 3A, and detachably connected to the fastener portion (loop element 612).

[0051] In the mattress 1A according to this embodiment, the first portion 2A and the second portion 3A can be detachably connected to each other via the first connecting means 61, and therefore the connected state of the first portion 2A and the second portion 3A can be maintained. On the other hand, if a part of either the first portion 2A or the second portion 3A is damaged, the connection between the first portion 2A and the second portion 3A is released by the first connecting means 61, and then only the damaged portion can be replaced.

[0052] Between the second portion 3A and the third portion 4A, a second connecting means 62 is disposed. The second connecting means 62 is specifically described as a mechanical fastener means consisting of a hook element 621 and a loop element 622, and for example, the loop element 622 is fixed to the second portion 3A, and the hook element 621 is fixed to the third portion 4A. More specifically, the mechanical fastener means has a fastener portion (loop element 622) located on the surface side exposed to the side surface of the second portion 3A, and a receiving portion (hook element 621) located on the surface side exposed to the side surface of the third portion 4A and releasably connected to the fastener portion (loop element 622).

[0053] In the mattress 1A according to this embodiment, the second portion 3A and the third portion 4A can be detachably connected to each other via the second connecting means 62, and therefore the second portion 3A and the third portion 4A can be maintained in a connected state by the second connecting means 62. On the other hand, if a part of either the second portion 3A or the third portion 4A is damaged, the second connecting means 62 can release the connection between the second portion 3A and the third portion 4A, and then only the damaged portion can be replaced.

[0054] As described above, the first portion 2A of the mattress 1A according to this embodiment has a recess 24 formed in a portion that contacts at least the back of the head BH of a person HU sleeping on his / her back, into which a part of the back of the head BH fits, and the recess 24 is configured so that the tip CH1 of the chin CH of the person HU sleeping on his / her back is located above the forehead FH. Therefore, the mattress 1A according to this embodiment has the same actions and effects as the mattress 1 described above. In addition, in the mattress 1A according to this embodiment, the first portion 2A only has the inclined surface 23F and the recess 24A, so that the configuration can be simplified.

[0055] Moreover, the mattress 1A of this embodiment comprises a first portion 2A on which the back of the head BH of the human HU sleeping on his / her back is placed, a second portion 3A on which the torso TR of the human HU sleeping on his / her back is placed, and a third portion 4A on which the legs LE of the human HU sleeping on his / her back is placed, the first portion 2A, the second portion 3A and the third portion 4A being formed separately, the first portion 2A having a first end portion 21 adjacent to the second portion 3A in the vertical direction L and a second end portion 22 located on the opposite side of the first end portion 21 in the vertical direction L, and a flat inclined surface 23F that is inclined so that the first end portion 21 is located downward D and the second end portion 22 is located upward U.

[0056] The mattress 1A of this embodiment includes a second portion 3A on which the torso TR of the human HU sleeping on his / her back rests, and a third portion 4A on which the legs LE of the human HU sleeping on his / her back rests, and therefore can prevent the sleeping human HU from sliding down toward the second end 22 of the first portion 2A.

[0057] Moreover, the mattress 1A according to this embodiment includes a first connecting means 61 that connects the first portion 2A and the second portion 3A, and a second connecting means 62 that connects the second portion 3A and the third portion 4A.

[0058] [Third embodiment] Next, a mattress 1B according to a third embodiment will be described with reference to Fig. 7. In the configuration of the mattress 1B according to the third embodiment, the same components as those in the configuration of the mattress 1A according to the second embodiment will be denoted by the same reference numerals and will not be described.

[0059] Fig. 7 is a perspective view of a mattress according to a third embodiment, showing a state in which the first portion 2A in the mattress 1B shown in Fig. 4 has been changed to a spare first portion 5. The mattress 1B according to this embodiment has the first portion 2A, the second portion 3A, the fourth portion A, and the spare first portion 5.

[0060] The length in the vertical direction L of the spare first portion 5 is the same as the length in the vertical direction L of the first portion 2A. In addition, the length in the width direction W of the spare first portion 5 is the same as the length in the width direction W of the first portion 2A. Furthermore, the height in the vertical direction H of the spare first portion 5 is the same as the height in the vertical direction H of the first end 21 of the first portion 2A.

[0061] The spare first portion 5 is formed of a material that contains an elastic material and that deforms when an object is placed on the upper side U in the vertical direction H. In other words, the material forming the spare first portion 5 is the same as the material forming each of the first portion 2A, the second portion 3A, and the third portion 4A.

[0062] Further, at an upper side U in the up-down direction H of the preliminary first portion 5, a top end surface 5F is formed which is flat without being inclined and extends along the horizontal direction.

[0063] In the vertical direction H, the height of the upper end surface 5F of the spare first part 5 and the height of the upper end surface 3F of the second part 3 are the same, and in the longitudinal direction L, no step is formed between the spare first part 5 and the second part 3.

[0064] Moreover, the mattress 1B according to this embodiment has a spare first part 5 on which the back of the head BH of the human HU lying on his back rests, and the first part 2A and the spare first part 5 are configured to be replaceable, and the entire upper surface of the spare first part 5 is configured to have a flat end surface 5F extending along the horizontal direction. That is, the mattress 1B according to this embodiment has the spare first part 5 replaceable with the first part 2A, and can be divided into a plurality of parts. For a human HU whose face and neck are not subjected to the appropriate force due to gravity G, the first part 2A can be changed to the spare first part 5 having a flat surface 5F on the upper side U, which is one side in the vertical direction H, to return the mattress 1B to a flat mattress having a flat surface as a whole.

[0065] [Fourth embodiment] Next, a mattress 1C according to a fourth embodiment will be described with reference to Fig. 8. In the configuration of the mattress 1C according to the fourth embodiment, the same components as those in the configuration of the mattress 1A according to the second embodiment will be denoted by the same reference numerals and will not be described.

[0066] 8 is a perspective view of a mattress 1C according to a fourth embodiment. The first portion 2C of the mattress 1C according to this embodiment does not have the recess 24 that the mattress 1A according to the second embodiment has, and the entire upper surface located on the upper side U in the vertical direction is formed into a sloping flat surface 23F.

[0067] Moreover, the mattress 1C according to this embodiment comprises a first portion 2C on which the back of the head BH of the human HU sleeping on his / her back is placed, a second portion 3A on which the torso TR of the human HU sleeping on his / her back is placed, and a third portion 4A on which the legs LE of the human HU sleeping on his / her back is placed, the first portion 2C having a first end 21 adjacent to the second portion 3A in the vertical direction L and a second end 22 located on the opposite side of the first end 21 in the vertical direction L, and a flat inclined surface 23F that is inclined so that the first end 21 is located at an upper U and the second end 22 is located at a lower D, and the inclined surface 23F is configured so that the tip CH1 of the chin CH of the human HU sleeping on his / her back is located at a higher U than the forehead FH.

[0068] The mattress 1C according to this embodiment has the above-mentioned configuration, and therefore exerts the same effects and advantages as the mattress 1A according to the second embodiment. Moreover, the mattress 1C according to this embodiment can prevent a gap from occurring between the neck of the person HU and the inclined surface 23F of the first portion 2C.

[0069] The above has been described based on the embodiments of mattresses 1, 1A, 1B, and 1C according to the present invention, but the present invention is not limited to the embodiments, and various modifications are possible within the scope of the present invention. In addition, the present invention also includes a configuration in which a portion of the components of each of the above-mentioned embodiments is appropriately combined. Such modifications that do not depart from the scope of the present invention are also included in the technical scope of the present invention, and this is clear to a person skilled in the art from the description of the claims. [Explanation of symbols]

[0070] 1, 1A, 1B, 1C Mattress 11 Main unit 11F 1st flat surface 12 Insertion parts 12F1 2nd flat surface 12F2 Component surface 2, 2A Part 1 21 First end 22 Second end 23F Slope 24 Recess 24F Concave curved surface 3, 3A 2nd part 4, 4A 3rd part 5. Spare Part 1 5F flat surface 61 First connection means 62 Second connection means D Downward (the other side in the up and down direction) H Vertical direction U Upward (either up or down)

Claims

1. A recess is provided in a portion where at least the back of the head of a person lying on his / her back comes into contact, into which a part of the back of the head fits, The recess is configured so that the tip of the chin of a person sleeping on his / her back is positioned higher than the forehead, The recess includes a recess body formed in a truncated cone shape and an extension portion connected to the recess body and extending along the width direction, The recess body has a bottom surface located downward in the vertical direction and a recess side surface rising obliquely from the bottom surface in the vertical direction, The bottom surface is inclined so that the end side closest to the head is deeper in the vertical direction and the end side closest to the legs is shallower, and is the part on which the back of the head of a person sleeping on his / her back is placed.

2. a body having the recess and a first flat surface; A fitting member that is fitted into the recess; Equipped with the fitting member has a second flat surface on one side in the up-down direction, and a fitting member curved surface on the other side in the up-down direction that contacts a recess curved surface that forms the recess, When the fitting member is fitted into the recess, the first flat surface of the main body and the second flat surface of the fitting member form a flat surface over the entire upper surface of the main body and the fitting member in the up-down direction.

2. The mattress of claim 1.

3. A first portion on which the back of the head of a person lying on his / her back rests; a second section for supporting the torso of a person lying on his back; a third section on which the legs of a person lying on his back rest; Equipped with the first portion, the second portion, and the third portion are integrally formed; 2. The mattress of claim 1.

4. A first portion on which the back of the head of a person lying on his / her back rests; a second section for supporting the torso of a person lying on his back; a third section on which the legs of a person lying on his back rest; Equipped with The first portion, the second portion, and the third portion are formed separately, The first portion has a first end adjacent to the second portion in a longitudinal direction and a second end located on an opposite side of the first end in the longitudinal direction, 2. The mattress of claim 1, having a flat slope that slopes such that the first end is located upward and the second end is located downward.

5. a first connecting means for connecting the first portion and the second portion; a second connecting means for connecting the second portion and the third portion; The mattress of claim 3 comprising:

6. a first auxiliary portion on which the back of the head of a person lying on his / her back rests; The first part and the spare first part are configured to be replaceable, The mattress of claim 3 , wherein the entire upper surface of the preliminary first portion is configured to have a flat surface along a horizontal direction.

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