mattress

Abstract

To provide a mattress that is more easily bendable than the traditional models, solving the problem in which the mattress is sometimes bent when raising the upper body of a person lying down on a reclining bed or the like.SOLUTION: In a mattress 10 formed by laminating a first layer 11 and a second layer 12, the first layer 11 has a groove 30 extending in the width direction at least on one side, front and back, and the second layer 12 does not have a groove extending in the width direction on the opposite side to the first layer 11.SELECTED DRAWING: Figure 1

Description

[[Technical Field]]

[0001] The present disclosure relates to a mattress. [[Background Art]]

[0002] For example, a mattress may be bent when raising the upper body of a person lying on a reclining bed (see, for example, Patent Document 1). [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Re-publication No. 2017 / 183670 (Figure 5, etc.) [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] There has been a demand for a mattress that is easier to bend than conventional mattresses. [[Means for Solving the Problem]]

[0005] A first aspect of the invention made to solve the above problem is a mattress in which a first layer and a second layer are laminated, wherein the first layer is provided with a groove extending in the width direction on at least one of the front and back surfaces, and the second layer is a mattress that does not have a groove extending in the width direction on a surface opposite to the first layer. [[Brief Description of the Drawings]]

[0006] [Figure 1] Front view of the mattress [Figure 2] Front view of the mattress during gatch up [Figure 3] Bottom view of the mattress [Figure 4] Top view of the mattress [Figure 5] Side view of the mattress [Figure 6] Enlarged front cross-sectional view of the mattress [Figure 7] Enlarged cross-sectional view of the area around the groove in the first layer [Figure 8] Enlarged front view of the central part of the mattress when the gatcha is raised. [Figure 9] Enlarged front view of the knee area of ​​the mattress when the headrest is raised. [Figure 10] Front view showing other uses of the mattress [Figure 11] Front view of the mattress in a different usage example when the headrest is raised. [Figure 12] (A) Front view of a mattress according to another embodiment, (B) Front view of a mattress according to another embodiment, (C) Front view of a mattress according to another embodiment [Figure 13] Front view of a conventional mattress when the headrest is raised. [Modes for carrying out the invention]

[0007] [First Embodiment] As shown in Figures 1 and 2, a mattress 10 according to one embodiment of the present disclosure has a two-layer structure in which a first layer 11 and a second layer 12 are laminated together. For example, the planar shape of the mattress 10 is approximately rectangular (see Figure 3), and it is foldable in the middle of its longitudinal direction (see Figure 2). Hereinafter, the surface of the mattress 10 on the first layer 11 side will be appropriately referred to as the first surface 11F, and the surface on the second layer 12 side will be appropriately referred to as the second surface 12S.

[0008] In this embodiment, the mattress 10 is placed on a reclining bed 90 for medical or nursing care. As shown in Figure 2, the bed 90 is folded (so-called gatch-up) for purposes such as raising the upper body of a person lying down, and the mattress 10 is folded accordingly. In the example of mattress 10 usage shown in Figures 1 and 2, the first layer 11 is placed on the upper side and the second layer 12 is placed on the lower side. The person lying down then lies on the first layer 11.

[0009] The first layer 11 and the second layer 12 may be made of a material that allows the mattress 10 to be bent and deformed, and may be made of an elastic material, for example. Examples of elastic materials include foam and rubber. From the viewpoint of reducing the weight of the mattress 10 and providing cushioning, it is preferable that the first layer 11 and the second layer 12 are made of foam. It is also preferable that the mattress 10 is breathable, as this prevents the person lying on it from getting sweaty. In this embodiment, the first layer 11 and the second layer 12 are made of a breathable foam (for example, a foam made of polyurethane resin) (for example, a foam with an open-cell structure), and the mattress 10 is also breathable in the thickness direction.

[0010] In this embodiment, the second layer 12 has lower hardness than the first layer 11 (characteristic A). Also, in this embodiment, the second layer 12 has a higher rebound modulus than the first layer 11 (characteristic B). The mattress 10 preferably has either characteristic A or characteristic B, and more preferably has both characteristics. For example, the hardness of the first layer 11 is preferably 160-240N, more preferably 180-220N, and even more preferably 190-210N. The rebound modulus of the first layer 11 is preferably 20-50%, more preferably 25-45%, and even more preferably 30-35%. The density (apparent density) of the first layer 11 is 20-40 kg / m³. 3 Preferably, it is 22-35 kg / m 3 It is more preferable that the load is 25-30 kg / m 3 It is even more preferable that the following conditions are met. For example, the hardness of the second layer 12 is preferably 80-150N, more preferably 90-135N, and even more preferably 110-120N. The rebound modulus of the second layer 12 is preferably 30-60%, more preferably 35-50%, and even more preferably 40-45%. The density (apparent density) of the second layer is 16-35 kg / m³. 3 Preferably, it is 18-30 kg / m 3 It is more preferable that the load is 20-24 kg / m³. 3is further more preferable. Note that the mattress 10 may also be configured to have neither of the above characteristics A and B. The above hardness can be measured in accordance with JIS K6400-2 (Method D). Further, the above impact resilience can be measured in accordance with JIS K6400-3.

[0011] As shown in Figure 1, in the present embodiment, the second layer 12 is thinner than the first layer 11. Note that the second layer 12 may have the same thickness as the first layer 11, or may be thicker than the first layer 11.

[0012] As shown in Figure 1 and Figure 4, the first layer 11 is formed with grooves 30 extending in the width direction of the first layer 11 (that is, the mattress 10). In the present embodiment, the grooves 30 are formed on both the front and back surfaces of the first layer 11. On the other hand, the second layer 12 is not provided with grooves extending in the width direction of the second layer 12 (of the mattress 10) on either the front or back surface thereof, and in the present embodiment, both the front and back surfaces of the second layer 12 are flat surfaces (see Figure 1 and Figure 5).

[0013] As shown in Figure 4, in the example of the present embodiment, the grooves 30 traverse the first layer 11 in the width direction and are, for example, linear. A plurality of grooves 30 may be provided in the longitudinal direction of the mattress 10, and in the example of the present embodiment, a plurality of grooves 30 parallel to each other are provided on each of both the front and back surfaces of the first layer 11.

[0014] As shown in Figure 1, in the example of the present embodiment, the grooves 30 on the front and back surfaces of the first layer 11 are arranged at the same position in the longitudinal direction of the mattress 10. Specifically, in the example of the present embodiment, the number of grooves 30 is the same on the front and back surfaces of the first layer 11, and the arrangement of the grooves 30 is also the same.

[0015] In this embodiment, as shown in Figure 6, a portion of the first layer 11 is provided in the thickness direction where neither the grooves 30 on the front and back surfaces of the first layer 11 reach. This makes it easy to ensure the strength of the first layer 11 even with the grooves 30 present. In this embodiment, the depth of the grooves 30 is less than half the thickness of the first layer 11. For example, among the multiple grooves 30, there may be grooves 30 whose depth is half or more the thickness of the first layer 11. Alternatively, the first layer 11 can be configured so that there is no portion in the thickness direction where the grooves 30 do not reach. In this configuration, the grooves 30 on the front and back surfaces of the first layer 11 can be offset in the longitudinal direction of the first layer 11.

[0016] Furthermore, in this embodiment, as shown in Figure 1, the spacing between the multiple grooves 30 is not constant, and the spacing between the grooves 30 (i.e., the distribution of the grooves 30) differs along the longitudinal direction of the mattress 10. Specifically, in the central part C along the longitudinal direction of the first layer 11, the distribution of the multiple grooves 30 is denser than in the longitudinally central parts B and D on either side. Also, for example, in the longitudinal ends or parts near the ends of the first layer 11 (for example, parts A and E shown in Figure 1), the distribution of the multiple grooves 30 is denser than in the central parts B and D. In the example shown in Figure 1, the distribution of the multiple grooves 30 along the longitudinal direction of the first layer 11 is densest in the central part C and parts A and E. Note that the spacing between adjacent grooves 30 may be two types or three or more types.

[0017] In this embodiment, the multiple grooves 30 are formed symmetrically along the longitudinal direction of the first layer 11. That is, in this embodiment, the entire mattress 10 has a symmetrical shape along its longitudinal direction. Furthermore, when viewed from the opposite side of Figure 1 in the width direction, the mattress 10 has the same shape as shown in Figure 1, and when viewed from the opposite side of Figure 5 in the longitudinal direction, it has the same shape as shown in Figure 5. Having a symmetrical shape along its longitudinal direction in this way is convenient because it allows the head of the person lying down to be positioned on either side of the longitudinal direction. In this embodiment, all the grooves 30 have the same shape, but it is also possible to make the shape of some of the grooves 30 different from the shape of the other grooves 30.

[0018] As shown in Figure 7, the groove 30 has a narrowed section 31 in the middle of its depth direction, which narrows the groove width, giving it a constricted shape. For example, the bottom surface 32 of the groove 30 is flat and is approximately parallel to the second layer 12. On the inner surface of the groove 30, a pair of sides 33 that face each other in the groove width direction are provided with a curved concave surface 33U and a curved bulge surface 33T. The curved concave surface 33U extends smoothly from the bottom surface 32 toward the opening 34 side of the groove 30 and forms an arc shape when viewed from the width direction of the first layer 11. The curved bulge surface 33T extends smoothly from the curved concave surface 33U toward the opening edge of the opening 34 and forms an arc shape when viewed from the width direction of the first layer 11. Thus, since the side surface 33 of the groove 30 is smoothly continuous with the bottom surface 32 and the opening edge of the opening 34 and does not have sharp corners, even when the mattress 10 is bent and deformed so that the groove 30 closes or opens, it is possible to suppress excessive localized stress concentration on a part of the inner surface of the groove 30. For example, the radius of curvature of the arc of the curved bulge surface 33T is larger than the radius of curvature of the arc of the curved concave surface 33U.

[0019] As shown in Figure 7, in this embodiment, the size of the opening 34 in the groove width direction (longitudinal direction of the first layer 11) of the groove 30 is larger than the size of the bottom surface 32. Also, in this embodiment, the distance between the pair of side surfaces 33 of the groove 30 is greatest at the opening 34.

[0020] In this embodiment, the angle α between the tangents drawn from the center P in the groove width direction of the bottom surface 32 to a pair of opposing narrow sections 31 (curved bulging surfaces 33T) is 30 degrees or more (for example, 35 degrees).

[0021] As described above, the mattress 10 of this embodiment is bent when the bed 90 is raised (see Figure 2). In this embodiment, since the groove 30 extends in the width direction of the first layer 11, the first layer 11, i.e., the mattress 10, can be easily bent in the middle of its longitudinal direction. Also, in this embodiment, since the groove 30 is provided on the first layer 11, which is thicker than the second layer 12, the mattress 10 can be effectively made easier to bend (see Figures 8 and 9).

[0022] As described above, the second layer 12 may have lower hardness or higher rebound modulus than the first layer 11. For example, as shown in other usage examples in Figures 10 and 11, the mattress 10 can also be used upside down compared to the usage example in Figure 1 (i.e., the first layer 11 is on the bottom and the second layer 12 is on top). By making the first layer 11 and the second layer 12 different in this way, the user can choose which of the first layer 11 or the second layer 12 to place on top according to their preference or symptoms, thereby broadening the range of choices. For example, depending on whether a user prefers a softer or firmer mattress 10, they can choose which layer with lower hardness and which with higher hardness to place on top. In this embodiment, since grooves 30 are formed on both the front and back surfaces of the first layer 11, the mattress 10 can be easily folded in either direction, thus increasing the reversibility of the mattress 10 (see Figures 2 and 11).

[0023] Furthermore, in a configuration as in this embodiment, where the first layer 11 is thicker and harder than the second layer 12, it is possible to ensure the strength of the mattress 10 with the first layer 11 while making the first layer 11 easier to bend with the groove 30. In addition, the user can choose whether or not to place the second layer 12 on top, according to their preference. In other words, a very user-friendly mattress 10 can be provided.

[0024] In this embodiment, since the grooves 30 on the front and back of the first layer 11 are located at the same position in the longitudinal direction of the first layer 11, the thickness of the areas in the first layer 11 where these grooves 30 are formed can be made thinner compared to when they are misaligned, making the first layer 11 easier to bend. On the other hand, since the first layer 11 has portions in its thickness direction where neither the front nor back grooves 30 reach, the strength of the first layer 11 can be ensured.

[0025] In this embodiment, the grooves are densely distributed in the central part C (see Figure 1) of the mattress 10 in the longitudinal direction, that is, the part that is frequently folded. Therefore, the benefits of the mattress 10's flexibility are more easily enjoyed, and its usability is further improved. In addition, the grooves 30 divide the receiving part 39 that supports the person lying down on the upper surface (first surface 11F) of the mattress 10, making it easier to deform the receiving part 39 in the thickness direction and longitudinal direction, and thus an improvement in pressure distribution can be expected compared to conventional designs. Here, the central part C in the longitudinal direction of the mattress 10 is also the part that supports protruding parts such as the buttocks and pelvis of the person lying down, and is a part that is easily subjected to pressure. Also, part E (see Figure 1) of the mattress 10 supports the head and shoulders of the person lying down, and part A supports the feet, so these parts E and A are similarly prone to pressure. In this embodiment, since the receiving portion 39 is divided into multiple parts by grooves 30 in the central portion C and portions A and E, it becomes possible to deform the receiving portion 39 more easily, and an improvement in pressure distribution can be expected. Moreover, as the distribution of grooves 30 in the central portion C and portions A and E becomes denser, it becomes possible to deform the first layer 11 more easily, and an even greater improvement in pressure distribution can be expected compared to the conventional design.

[0026] Furthermore, the mattress 10 of this embodiment can also be expected to reduce abdominal pressure during bed reclining, as described below. As shown in Figures 2 and 13, when performing a back-raising bed reclining to raise the upper body of a person lying on their back, a knee-raising bed reclining is sometimes performed by raising the knee area of ​​the bed 90 to support the buttocks and prevent the upper body from sliding down. In this case, as the upper body and knees are raised upward, pressure is applied to the abdomen from above and below (abdominal pressure is applied) (see the direction of the arrows in Figure 13), which can cause discomfort in the abdominal area of ​​the person lying on their side. At this time, the central part C (near the buttocks) in the longitudinal direction of the mattress 100 becomes a valley-fold state with a concave surface on the top, so the top surface of the mattress 100 shrinks compared to before bed reclining. Furthermore, when the backs of the thighs and buttocks of the person lying on their side are fixed in place by friction with the mattress 100 (part B), and the back is fixed in place with the mattress 100 (part D), it is thought that the person lying on their side will experience a force that causes their body to contract (see the direction of the arrows in Figure 13). As a result, discomfort such as abdominal pressure and a feeling of pressure or tightness in the back and buttocks becomes more likely. Moreover, when the back is raised, the back of the person lying on their back is bent in a way that stretches it, and tries to shift in the opposite direction to the contraction of the upper surface of the mattress 100, so the friction described above becomes stronger, and it is thought that the discomfort described above becomes more likely to be felt.

[0027] In this situation, a healthy person can move on their own to temporarily separate their body from the mattress, thereby releasing the pressure between them and providing relief. However, a person lying down who has difficulty moving on their own needs someone else to perform this task of separating their body from the mattress, which presents a problem as they cannot immediately find relief.

[0028] In contrast, the mattress 10 of this embodiment (see Figure 2) has grooves 30 extending in the width direction, which provides a portion where the first layer 11 is thinner. Compared to a conventional mattress 100 (see Figure 13) with a constant thickness and no grooves 30, it is possible to reduce the force that tries to compress the person lying on their side in the longitudinal direction of the mattress 10, and thus alleviate the discomfort of abdominal pressure and the like. Furthermore, in the mattress 10 of this embodiment, the presence of grooves 30 divides the receiving portion 39 (see Figure 2, etc.) on the upper surface of the first layer 11 that receives the person lying on their side in the longitudinal direction. Compared to a configuration without grooves 30, the upper surface of the mattress 10 is more prone to shifting in the longitudinal direction, and it is thought that this makes it possible to release longitudinal forces acting on the body (for example, forces acting in the direction that causes the body to contract).

[0029] Furthermore, if the backrest is raised, even after the above backrest removal procedure, gravity may cause the upper body to be biased to slide downward relative to the mattress 100 (see the direction of the arrow in Figure 13). Here, as described above, friction occurs between the mattress and the body, so the person lying on their side may feel discomfort such as tightness. In contrast, in the mattress 10 of this embodiment, as described above, the upper surface of the mattress 10 is divided in the longitudinal direction by the grooves 30, so the receiving portion 39 between the grooves 30 can easily move (deform) in the longitudinal direction (downward) to match the body of the person lying on their side, and it is expected that discomfort such as tightness will be reduced.

[0030] Furthermore, when the backrest and knees are raised, it is conceivable that pressure may be felt in the direction of the mattress's thickness around the buttocks and thighs. However, because the upper surface of the mattress 10 is divided by the groove 30, it becomes easier to compress the support portion 39 in the direction of the mattress 10's thickness compared to when it is not divided. This is thought to help reduce the feeling of pressure around the buttocks and thighs.

[0031] Furthermore, by having grooves 30 extending in the width direction on the upper surface, the mattress 10 becomes more flexible compared to a conventional mattress 100 with a constant thickness. This suppresses the undulation of the mattress 10 when the bed is raised, preventing localized bulges on the upper surface of the central part C, thus reducing discomfort in the back and waist.

[0032] In addition, in the examples shown in Figures 10 and 11, the groove 30 in the first layer 11 is provided, which divides the receiving portion 39 on the upper surface of the first layer 11 that receives the person lying on their side in the longitudinal direction, and also provides a portion of the first layer 11 that is thinner. Therefore, when the mattress 10 is folded, the force that tries to compress the body of the person lying on their side can be suppressed, and abdominal pressure can be reduced.

[0033] Furthermore, as described above, when raising the knees and bending the knees, the portion of the mattress 10 behind the user's knees bends in the opposite direction from the area near the buttocks (see Figure 8) (it bends so as to be convex upwards), as shown in Figure 9. In contrast, in the mattress 10 of this embodiment, grooves 30 are provided on both sides of the first layer 11, so the first layer 11 (i.e., the mattress 10) can be easily folded in either direction.

[0034] As shown in Figure 7, in this embodiment, the angle α between the tangents drawn from the center P in the groove width direction on the bottom surface 32 of the groove 30 to a pair of opposing narrow sections 31 is 30 degrees or more. Here, in medical and nursing care settings, it is common to set the reclining angle θ of the bed 90 from the horizontal (see Figure 2) to 30 degrees or more to prevent aspiration, and it is also common to change the reclining angle θ to 30 degrees or more to prevent bedsores. Therefore, when the angle α between the tangents is 30 degrees or more, the narrow sections 31 will not touch or will not touch until the part of the first layer 11 in which the groove 30 is formed is bent to 30 degrees. As a result, the first layer 11 (i.e., the mattress 10) becomes easier to bend, and the mattress 10 becomes easier to follow the reclining of the bed 90. Furthermore, if the angle α of one groove 30 is 30 degrees or more, it becomes possible to locally fold the mattress 10 in the area where the groove 30 is located, making it easier to fold the mattress 10.

[0035] Furthermore, since the curved bulge surface 33T provided on the side surface 33 of the groove 30 is arc-shaped, when the mattress 10 is bent so that the opening 34 is closed, it becomes possible to further bend the first layer 11 to close the opening 34 by bringing the curved bulge surfaces 33T into contact with each other even after the narrower sections 31 have come into contact (see Figure 8), making it even easier to bend the mattress 10.

[0036] [Other embodiments] (1) The mattress 10 does not have to be placed on a medical or nursing care bed. The mattress 10 of this disclosure is suitable because it is easy to bend when rolling up or folding it for storage, for example.

[0037] (2) In the above embodiment, the mattress 10 may be used covered with a cover, such as a bag.

[0038] (3) In the above embodiment, the groove 30 was provided on both the front and back surfaces of the first layer 11, but it may also be provided on only one of the front and back surfaces of the first layer 11 (see Figures 12(A), 12(B), and 12(C)). The surface of the first layer 11 on which the groove 30 is not formed may be a flat surface, or a groove extending in the longitudinal direction may be formed on this surface instead of a groove 30 extending in the width direction of the first layer 11.

[0039] (4) In the above embodiment, both the front and back surfaces of the second layer 12 were flat, but grooves extending in the longitudinal direction of the second layer 12 may be formed on at least one of the front and back surfaces of the second layer 12. Alternatively, grooves extending in the width direction of the second layer 12 may be formed on the surface of the second layer 12 facing the first layer 11 (see Figure 12(C)).

[0040] (5) In the above embodiment, the grooves 30 were formed at the same position in the longitudinal direction on both the front and back of the first layer 11, but they may be formed at different positions on the front and back. Also, the number of grooves 30 may differ on the front and back of the first layer 11.

[0041] (6) In the above embodiment, the distribution of grooves 30 varied in the longitudinal direction of the first layer 11, but it may be constant.

[0042] (7) In the above embodiment, all grooves 30 have the same shape, however some grooves 30 may have a different shape from the other grooves 30.

[0043] (8) In the above embodiment, the arrangement of the grooves 30 was symmetrical in the longitudinal direction of the first layer 11, but it may be asymmetrical.

[0044] (9) In this embodiment, the mattress 10 had a two-layer structure consisting of a first layer 11 and a second layer 12, but it may also have a laminated structure of three or more layers including the first layer 11 and the second layer 12. In this case, for example, the first layer 11 and the second layer 12 may be the outermost layers, with one or more layers placed between them, or at least one of the first layer 11 and the second layer 12 may not be the outermost layer. When the mattress 10 has a structure of three or more layers, grooves extending in the width direction or longitudinal direction may or may not be formed in the layers other than the first layer 11 and the second layer 12. As a laminated structure for bonding multiple layers together, a two-layer structure is preferable from the viewpoint of preventing stuffiness for the person lying down, as it reduces the amount of adhesive between layers, making it easier to ensure the breathability of the mattress 10. The mattress 10 may also have a single-layer structure. In this case, for example, the mattress 10 may consist only of the first layer 11 shown in Figure 1.

[0045] <Note> The following describes the features extracted from the above embodiment, showing their effects and modifications as needed.

[0046] For example, the following set of features can be considered to have been conceived with the background technology of mattresses, specifically regarding mattresses, where "for example, when raising the upper body of a person lying on their side in a reclining bed, the mattress may be bent (see, for example, re-examined Patent Publication No. 2017 / 183670 (Figure 5, etc.))." and addressing the problem of "the need for a mattress that is easier to bend than conventional ones." Furthermore, there is a desire for the development of a new mattress that is unlike any conventional one.

[0047] [Feature 1] A mattress having a first layer and a second layer stacked together, The first layer has grooves extending in the width direction on at least one of its front and back surfaces, The second layer is a mattress that does not have grooves extending in the width direction on the side opposite to the first layer.

[0048] In this feature, since the groove extends in the width direction of the first layer, the first layer, i.e., the mattress, can be easily bent in the middle of its longitudinal direction.

[0049] [Feature 2] The mattress according to feature 1, wherein the grooves are provided in multiple locations on both the front and back surfaces of the first layer, in the longitudinal direction of the first layer, and the grooves on the front and back surfaces are arranged at the same position in the longitudinal direction.

[0050] In this feature, the grooves on the front and back of the first layer are positioned at the same location along the longitudinal direction of the first layer. This allows the thickness of the areas where these grooves are formed in the first layer to be reduced, making the mattress easier to bend.

[0051] [Feature 3] The mattress according to feature 1 or 2, wherein the second layer has lower hardness and / or a higher rebound modulus than the first layer.

[0052] This feature allows users to choose which layer to place on top, according to their preferences or symptoms, by making the first and second layers different.

[0053] By incorporating grooves extending in the width direction into the first layer, which has a higher hardness than the second layer, it becomes possible to make the mattress more effectively flexible.

[0054] [Feature 4] The second layer is thinner than the first layer, and the mattress is described in any one of the features 1 to 3.

[0055] In this design, the first layer is thicker than the second layer, which would normally make the first layer more difficult to bend. However, by incorporating grooves into the first layer, the mattress can be made more effectively flexible.

[0056] [Feature 5] The mattress according to any one of the features 1 to 4, wherein the depth of the groove is less than half the thickness of the first layer.

[0057] [Feature 6] The grooves are formed on both the front and back surfaces of the first layer. The mattress according to any one of features 1 to 5, wherein a portion is provided in the thickness direction of the first layer where neither of the grooves on both sides of the first layer reaches.

[0058] This feature makes it possible to ensure the strength of the first layer.

[0059] [Feature 7] Multiple grooves are provided, and the distribution of these grooves differs in the longitudinal direction of the first layer. The mattress according to any one of features 1 to 6, wherein the distribution of the plurality of grooves is denser in the longitudinal central part of the first layer than in the longitudinal central parts on both sides thereof.

[0060] [Feature 8] The mattress according to feature 7, wherein the distribution of the plurality of grooves is denser at both ends or near both ends in the longitudinal direction of the first layer than in the central portion.

[0061] [Feature 9] A mattress having grooves extending in the width direction on at least one of its front and back surfaces, Multiple grooves are provided, and the distribution of these grooves differs in the longitudinal direction of the mattress. The mattress according to feature 1 or 2, wherein the distribution of the plurality of grooves is denser in the central part in the longitudinal direction than in the parts closer to the center in the longitudinal direction on both sides thereof.

[0062] In features 7-9, the distribution of grooves becomes denser in the central part of the mattress along its longitudinal direction, i.e., the part that is frequently folded. Therefore, the benefits of the mattress's ease of folding become more apparent, further improving its usability. Also, the central part of the mattress along its longitudinal direction is the part that is most likely to come into contact with protruding parts such as the buttocks and pelvis of a person lying on their side, and is therefore a part that is easily subjected to pressure. In features 7-9, the denser distribution of grooves in this central part makes it possible to deform the first layer more easily, and it is expected that the pressure distribution will be improved compared to conventional mattresses. For example, the mattress in feature 9 may have a laminated structure or a single-layer structure. Also, for example, the mattress in feature 9 may have grooves on only one side.

[0063] While this specification and drawings disclose specific examples of the technology included in the claims, the technology described in the claims is not limited to these specific examples, but also includes various modifications and changes to these examples, as well as parts of the examples taken individually. [Explanation of symbols]

[0064] 10 Mattresses 11 1st layer 12 2nd layer 30 grooves

Claims

1. A mattress having a two-layer structure, comprising only two layers: a first layer and a second layer having a higher modulus of resilience than the first layer, The first layer has grooves extending in the width direction on at least one of its front and back surfaces, The second layer is a mattress that does not have grooves extending in the width direction on the side opposite to the first layer.

2. A mattress comprising a first layer and a second layer having a higher rebound modulus than the first layer, The first layer has grooves extending in the width direction on both its front and back surfaces, The grooves are provided in multiple locations on both the front and back surfaces of the first layer, in the longitudinal direction of the first layer, and the grooves on the front and back surfaces are arranged at the same position in the longitudinal direction. The second layer is a mattress that does not have grooves extending in the width direction on the side opposite to the first layer.

3. A mattress comprising a first layer and a second layer having lower hardness than the first layer and a higher rebound modulus than the first layer, The first layer has grooves extending in the width direction on at least one of its front and back surfaces, The second layer is a mattress that does not have grooves extending in the width direction on the side opposite to the first layer.

4. A mattress comprising a first layer and a second layer having a higher rebound modulus than the first layer, The first layer has grooves extending in the width direction on at least one of its front and back surfaces, Multiple grooves are provided, and the distribution of these grooves differs in the longitudinal direction of the first layer. In the longitudinal central portion of the first layer, the distribution of the plurality of grooves is denser than in the longitudinal central portions on both sides thereof. The second layer is a mattress that does not have grooves extending in the width direction on the side opposite to the first layer.

5. A mattress comprising a first layer and a second layer having a higher rebound modulus than the first layer, The first layer has grooves extending in the width direction on at least one of its front and back surfaces, The depth of the groove is less than half the thickness of the first layer. The second layer is a mattress that does not have grooves extending in the width direction on the side opposite to the first layer.

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