Selective recharging mattress system based on stacked air cells

Abstract

A stacked air cell-based selective rechargeable mattress system according to the present invention comprises: a lower mattress including a plurality of air cells; an upper mattress stacked on the lower mattress and including a plurality of air cells and a pressure sensor; an air supply system connected to the upper mattress and the lower mattress via a supply line, wherein the supply line connected to the upper mattress is connected via a shut-off valve; and a controller having a determination module that determines whether recharging is necessary based on a measurement value of the pressure sensor, and a supply control module that, upon determining recharging, temporarily suspends pressure control of the lower mattress, opens the shut-off valve to supply air from the air supply system to the upper mattress, and after supply is completed, closes the shut-off valve and resumes pressure control of the lower mattress. According to the stacked air cell-based selective recharge mattress system of the present invention, by stacking a lower mattress and an upper mattress in independent pressure paths and including a selective recharge structure comprising isolated operation of the upper mattress through a shut-off valve and temporary suspension and resumption of pressure control of the lower mattress during recharge, the active pressure control of the lower mattress and the independent pressure environment of the upper mattress can coexist without mutual interference, and the body pressure distribution performance of the upper mattress is immediately restored after recharge is completed.

Description

Technology Field

[0001] The present invention relates to a selective rechargeable mattress system based on stacked air cells, and more specifically, to a mattress system in which a lower mattress and an upper mattress are stacked in an independent pressure path and the upper mattress is normally isolated from the air supply system through a shut-off valve, and when a judgment module determines that recharging is necessary based on the measurement value of a pressure sensor, pressure control of the lower mattress is temporarily suspended, air is selectively refilled only to the upper mattress, and pressure control of the lower mattress is resumed after refilling is completed. Background Technology

[0002] An air mattress is a cushioning device containing multiple air cells filled with air, and has a structure that supports and distributes the user's body weight through the air pressure inside the air cells.

[0003] Air mattresses are being utilized across various fields, such as medical pressure sore prevention mattresses and smart mattresses for improving sleep quality, as they can adjust internal air pressure to provide varying support tailored to the user's body shape or sleeping position compared to spring or foam-based mattresses.

[0004] Due to the material properties of the air cells in air mattresses, the internal air pressure tends to gradually decrease with long-term use due to microscopic permeation of air molecules and leakage at the joints.

[0005] To compensate for this, an automatic replenishment system has been developed that detects air pressure and replenishes air through a pump. Korean Registered Patent No. 10-1319735 (hereinafter referred to as the 'prior art') discloses a system and method for maintaining the composition of an air-inflatable mattress.

[0006] This prior art discloses a structure that measures the irradiation level inside a plurality of expansion chambers constituting a mattress using an infrared sensor, and replenishes air by monitoring the expansion state of each chamber or group of chambers through a distributed microprocessor controller.

[0007] However, the prior art constructs the mattress as a single structure in which all chambers share a single supply path, and thus does not disclose a structure that operates by separating the upper region, which is responsible for distributing body pressure in direct contact with the user, and the lower region, which is responsible for supporting the load, into independent pressure paths.

[0008] As a result, there is a limitation in that it is difficult to maintain the pressures of the two regions independently, as the pressure environment of the upper region is also affected while air pressure control is being performed in the lower region.

[0009] Furthermore, since the aforementioned prior art does not disclose a blocking means for isolating the pressure environment of the upper region from external supply fluctuations by normally blocking the fluid connection between the air supply system and the mattress, it is structurally difficult to prevent a situation in which the internal air pressure of the upper region is affected by the pressure control operation of the lower region.

[0010] Furthermore, the prior art does not disclose a sequential recharge control structure that temporarily suspends pressure control in the lower region during air replenishment, selectively replenishes air only in the upper region, and resumes pressure control in the lower region after replenishment is complete, making it difficult to prevent a situation where recharging in the upper region interferes with the support pressure in the lower region.

[0011] Therefore, there is a need to develop a novel and advanced technology that stacks a lower mattress and an upper mattress via independent pressure paths and normally isolates the upper mattress through a shut-off valve, but temporarily suspends pressure control of the lower mattress and selectively replenishes air only to the upper mattress when recharging is determined, and then resumes pressure control of the lower mattress. Prior art literature

[0012] Korean Registered Patent No. 10-1319735 The problem to be solved

[0013] The present invention was devised to overcome the problems of the above technology, and its main purpose is to provide a mattress system in which the pressure environments of the two mattresses are maintained independently without mutual interference by stacking a lower mattress and an upper mattress in independent pressure paths and normally isolating the upper mattress from the air supply system through a shut-off valve, and, when a judgment module based on the measurement value of a pressure sensor determines that recharging is necessary, temporarily suspending pressure control of the lower mattress, selectively replenishing air only to the upper mattress, and resuming pressure control of the lower mattress after replenishment is complete.

[0014] Another objective of the present invention is to provide an upper mattress structure in which the air cells of the upper mattress are composed of microcells with a diameter of 30 to 80 mm, and a plurality of microcells connected by a connecting channel are grouped into cluster units, with a check valve and a throttling member arranged in parallel between adjacent clusters, thereby separating the rapid pressure redistribution within the clusters and the gentle air flow between clusters on the time axis, so that local pressure relief and overall subsidence are simultaneously achieved.

[0015] Another objective of the present invention is to provide a recharge determination structure in which the body pressure distribution performance of the upper mattress is maintained at an appropriate level in response to both situations where the pressure drop rate is fast and situations where it is slow, by having the trigger determination unit determine that recharge is needed when at least one of the cases where the measured value of the pressure sensor drops below the recharge threshold and when the recharge cycle has elapsed. means of solving the problem

[0016] To achieve the above objective, the stacked air cell-based selective rechargeable mattress system according to the present invention comprises: a lower mattress including a plurality of air cells; an upper mattress stacked on the lower mattress and including a plurality of air cells and a pressure sensor; an air supply system connected to the upper mattress and the lower mattress via a supply line, wherein the supply line connected to the upper mattress is connected via a shut-off valve; and a controller having a determination module that determines whether recharging is necessary based on the measurement value of the pressure sensor, and a supply control module that, upon determining recharging, temporarily suspends pressure control of the lower mattress, opens the shut-off valve to supply air from the air supply system to the upper mattress, and after supply is completed, closes the shut-off valve and resumes pressure control of the lower mattress.

[0017] In addition, the air cell of the upper mattress is a microcell with a diameter of 30 to 80 mm, and the upper mattress is characterized by including a plurality of clusters including a plurality of microcells connected by a communication channel, a check valve installed in a first connecting channel connecting adjacent clusters, and a constricting member installed in a second connecting channel connecting adjacent clusters.

[0018] In addition, the above-described judgment module is characterized by including a trigger judgment unit that determines that recharging is required if at least one of the cases where the measured value of the pressure sensor falls below a preset recharging threshold or where a preset recharging cycle has elapsed. Effects of the invention

[0019] According to the stacked air cell-based selective rechargeable mattress system of the present invention,

[0020] 1) By a structure in which the lower mattress and the upper mattress are stacked with independent pressure paths and the upper mattress is normally isolated through a shut-off valve, but pressure control of the lower mattress is temporarily suspended during recharging and air is selectively replenished only in the upper mattress, and pressure control of the lower mattress is resumed after completion, the active pressure control of the lower mattress and the independent pressure environment of the upper mattress can coexist without mutual interference, and the body pressure distribution performance of the upper mattress is immediately restored after recharging is complete,

[0021] 2) By a structure in which the trigger judgment unit independently performs at least one of pressure-based judgment and cycle-based judgment, conditions are secured that recharging can be initiated at a point before the pressure drop of the upper mattress affects the body pressure distribution performance, regardless of the air leakage rate of the air cell or the usage environment.

[0022] 3) By a structure in which the reduction rate calculation part and the priority calculation part calculate the pressure reduction rate in real time and evaluate the recharge priority in combination according to Equation 1, it is possible to detect early on a situation where the pressure reduction rate increases rapidly even when the measurement value of the pressure sensor has not reached the recharge threshold, thereby enabling preemptive initiation of recharge without a decrease in body pressure distribution performance. Brief explanation of the drawing

[0023] FIG. 1 is a block diagram illustrating the overall configuration of a stacked air cell-based selective rechargeable mattress system of the present invention. FIG. 2 is a perspective view illustrating the stacked structure of the upper mattress and lower mattress of the present invention. FIG. 3 is a conceptual diagram illustrating the connection structure of a plurality of clusters, check valves, and throttling parts formed on the upper mattress of the present invention. FIG. 4 is a conceptual diagram illustrating the state of air flow from a cluster located in the waist-corresponding region of the present invention toward surrounding clusters. FIG. 5 is a flowchart illustrating the process of determining whether recharging is necessary and recharging the upper mattress according to the present invention. FIG. 6 is a graph illustrating the state in which the recharge threshold is adjusted according to the pressure reduction rate and pressure control pause time of the present invention. Specific details for implementing the invention

[0024] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The attached drawings are not drawn to scale, and the same reference numerals in each drawing refer to the same components.

[0025] The stacked air cell-based selective rechargeable mattress system of the present invention (hereinafter referred to as the "system") has the main purpose of allowing a controller (400) to selectively recharge the upper mattress (200) without interfering with the pressure control of the lower mattress (100) in an upper-lower stacked structure of the lower mattress (100) and the upper mattress (200), in contrast to conventional integrated mattresses which are provided as a single structure and make it difficult to independently control pressure in the upper and lower regions.

[0026] At this time, selective recharging refers to a series of processes in which, only when a drop in pressure of the upper mattress (200) is detected, pressure control of the lower mattress (100) is temporarily suspended, air is replenished only in the upper mattress (200), and pressure control of the lower mattress (100) is resumed after replenishment is completed.

[0027] In other words, the system of the present invention maintains the pressure in the upper and lower regions independently in an upper and lower stacking structure, and replenishes the upper mattress (200) only when the pressure drops, without interfering with the control of the lower mattress (100).

[0028] The configuration and functions of the system of the present invention will be described in detail below.

[0029] FIG. 1 is a block diagram illustrating the overall configuration of the stacked air cell-based selective rechargeable mattress system of the present invention.

[0030] As can be seen from FIG. 1, the system of the present invention is based on including a lower mattress (100), an upper mattress (200), an air supply system (300), and a controller (400).

[0031] FIG. 2 is a perspective view illustrating the stacked structure of the upper mattress and lower mattress of the present invention.

[0032] The mattress of the present invention is a so-called air mattress based on air cells (110), and is structured such that a lower mattress (100) and an upper mattress (200) have independent pressure paths.

[0033] The lower mattress (100) is a base structure positioned at the bottom of the system to support the upper mattress (200) and includes a plurality of air cells (110).

[0034] The lower mattress (100) is directly connected to the air supply system (300) through the supply line (320), so that the internal air pressure of each air cell (110) can be adjusted according to the control of the controller (400).

[0035] At this time, a shut-off valve (310) is not installed in the supply line (320) between the lower mattress (100) and the air supply system (300), so the lower mattress (100) can remain constantly connected to the air supply system (300).

[0036] In other words, the lower mattress (100) allows for free air supply and exhaust from the air supply system (300), enabling bidirectional control to raise or lower the air pressure of the air cell (110).

[0037] The air cell (110) may be independent or multiple air cells (110) may form a group to control the pressure.

[0038] For example, depending on the support requirements for each body part of the user, the area may be divided into a head corresponding area, a waist corresponding area, and a lower limb corresponding area, and different target pressures may be set in the air cells (110) of each area.

[0039] The connection structure between the air cell (110) and the air supply system (300) can be implemented in various ways.

[0040] As an example, a structure may be formed in which individual valves are installed in each air cell (110) so that air is supplied and exhausted independently for each air cell (110), or a structure may be formed in which multiple air cells (110) are connected in parallel to a common supply line so that air is controlled on a zone basis.

[0041] As another example, a structure in which air is distributed to multiple air cells (110) from a single source through a manifold is also possible.

[0042] The material of the air cell (110) may be formed from a material requiring durability and airtightness, such as thermoplastic polyurethane (TPU) or rubber-based material, but is not limited thereto. The air cell may be formed by joining two elastic sheets. For example, the sheets may be joined by a heat fusion method to form a sealed air space inside, and as another example, a high-frequency (RF) welding method may be used.

[0043] The shape of the air cell can be implemented differently depending on design requirements. For example, it can be formed into a spherical or cylindrical shape, or, as an example, molded into a cushion shape corresponding to a part of the user's body.

[0044] The arrangement of air cells can be implemented in various forms. For example, multiple air cells can be arranged in a grid pattern, or, as another example, a structure in which they are arranged in a honeycomb shape to increase the air cell density per unit area is also possible.

[0045] The upper mattress (200) is a layer that is laminated on the upper surface of the lower mattress (100) and comes into direct contact with the user, and may include a plurality of air cells and pressure sensors (280).

[0046] The air cells of the upper mattress (200) can be implemented with the same material or shape as the air cells of the lower mattress (100) described above, or they can be implemented with a different material or shape.

[0047] In addition, the size of the air cells of the upper mattress (200) may be the same as or different from the air cells of the lower mattress (100). In particular, for fine body pressure distribution, microcells smaller in size than the air cells of the lower mattress (100) may be applied to the air cells of the upper mattress (200), and this will be described later.

[0048] The pressure sensor (280) is for measuring the internal air pressure of the upper mattress (200) and can be implemented as a small sensor module including a semiconductor pressure element or a capacitive element.

[0049] These pressure sensors can be arranged in various structures inside the upper mattress (200).

[0050] For example, a structure may be adopted in which a representative air cell corresponding to a reference position within the upper mattress (200) is directly installed inside, and the air pressure of the air cell is used to estimate the internal air pressure of the entire upper mattress (200).

[0051] As another example, a structure is also possible in which multiple air cells are grouped by zone, and a pressure sensor (280) is installed in one representative air cell for each zone to measure the air pressure for each zone individually.

[0052] As another example, a pressure sensor (280) may be installed on a path communicating with an air cell to measure the representative pressure of a plurality of air cells.

[0053] Meanwhile, the air cells of the upper mattress (200) may have structural characteristics specialized for dispersing body pressure, and a detailed explanation of this will also be provided later.

[0054] The air supply system (300) is a device that supplies air to the lower mattress (100) and the upper mattress (200), and may include a pump, an air tank, a flow path, and valves, similar to a general air mattress drive unit.

[0055] The pump is a device that generates pressure within the air supply system (300), and for example, a small electric pump or a piezoelectric micro pump may be used.

[0056] The air tank can act as a buffer to temporarily store compressed air generated from the pump.

[0057] For example, by providing an air tank, a stable air supply can be ensured even during intermittent operation of the pump, and a structure in which air is supplied directly from the pump without the air tank is also possible.

[0058] The supply line (320) is a fluid path that guides air from the air supply system (300) to the lower mattress (100) and the upper mattress (200).

[0059] For example, one line may be branched from the air supply system (300) into a line connected to the lower mattress (100) and a line connected to the upper mattress (200), and each line may be further branched into one or more lines according to the number of air cells or zones within the mattress to supply air to each air cell or zone.

[0060] As another example, a structure can be applied in which independent lines are directly connected from the air supply system (300) to the upper mattress (200) and the lower mattress (100), respectively, so that air supply to the two mattresses is achieved without interference with each other.

[0061] As another example, a structure is also possible in which multiple lines branch from a single source through a manifold to distribute air to each air cell or zone.

[0062] The shut-off valve (310) is an active valve that selectively opens or closes a fluid path by an external electric signal, and can be implemented in various structures such as a solenoid valve in which a plunger is actuated by an electric coil, an electric valve driven by an electric actuator, or a pinch valve that blocks the flow path by compressing a flexible tube from the outside.

[0063] A shut-off valve (310) is installed on a supply line (320) connecting the air supply system (300) and the upper mattress (200), and can control the air flow to the upper mattress (200) by opening and closing according to a control signal from a controller (400).

[0064] The design significance of the shut-off valve (310) can be explained through its structural contrast with the lower mattress (100).

[0065] Unlike the lower mattress (100), which is always connected to the air supply system (300) without a shut-off valve (310) and whose pressure can be adjusted at any time according to the control of the controller (400), the upper mattress (200) maintains a state in which the fluid connection with the air supply system (300) is normally blocked by the shut-off valve (310), so that the air pressure inside the air cell can be maintained independently without being affected by external supply fluctuations.

[0066] In other words, the shut-off valve (310) blocks the internal air pressure of the upper mattress (200) from the influence of the air supply system (300), thereby creating an independent pressure environment for the upper mattress (200) alone.

[0067] As such, the placement of a single shut-off valve (310) can serve as a key design element of the present invention, determining different operation methods such as real-time pressure control of the lower mattress (100) and isolation operation of the upper mattress (200).

[0068] The controller (400) of the present invention is a control unit that integrally processes a series of selective refill flows, which determines whether refilling is necessary based on air pressure information of the upper mattress (200) received from the pressure sensor (280), temporarily suspends pressure control of the lower mattress (100) when refilling is determined, opens the shut-off valve (310) to replenish air in the upper mattress (200), and after refilling is completed, closes the shut-off valve (310) and resumes pressure control of the lower mattress (100).

[0069] The controller (400) can be implemented as a combination of hardware and software.

[0070] Hardware may include processing elements such as an ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), and microcontroller (MCU), a memory for storing the computational results and program commands of the processing elements, a communication interface circuit for communication with a pressure sensor (280), and a driver circuit for driving a shut-off valve (310) and an air supply system (300).

[0071] As software, firmware or embedded software may be employed in which a processing element executes program instructions stored in memory to perform the respective functions of the judgment module (410) and supply control module (420) described later.

[0072] Each module described below represents a logical functional unit and does not necessarily have to be separated into physically independent circuits or components, and can be implemented in a form where each function is executed separately in software on a single processor.

[0073] Specifically, the controller (400) includes a judgment module (410) and a supply control module (420).

[0074] The determination module (410) performs the role of determining whether the upper mattress (200) needs to be recharged based on the measurement value received from the pressure sensor (280).

[0075] The criteria for determining whether recharging is necessary by the judgment module (410) can be divided into, for example, pressure-based judgment and cycle-based judgment.

[0076] In a pressure-based determination, the determination module (410) receives the measurement value of the pressure sensor (280) in real time and compares it with a preset recharge threshold, and detects when the measurement value drops below the recharge threshold to determine that recharging is required.

[0077] The recharge threshold can be set based on the reference charging pressure of the upper mattress (200), for example, in the range of 85 to 95% of the reference charging pressure.

[0078] For example, when the internal air pressure of the upper mattress (200) gradually decreases due to fine air leakage from long-term use and falls below the recharge threshold, the judgment module (410) can detect this and transmit a recharge start signal to the supply control module (420).

[0079] In a cycle-based determination, the determination module (410) can internally track the time elapsed since the last recharge point and determine that recharging is required regardless of the level of the pressure measurement value when a preset recharge cycle has elapsed.

[0080] This is intended to compensate for cases where it takes a long time for the measured value to reach the recharge threshold due to gradual pressure drop, such as the micro-permeation of air molecules through the air cell material.

[0081] For example, in a situation where it is difficult to detect the need for recharging in a timely manner using only pressure-based judgment, even if air permeation through the air cell accumulates during nighttime sleep and the change in measurement value is minimal, a cycle-based judgment can operate independently to determine the need for recharging. In this case, the recharging cycle can be set, for example, within a range of 12 to 48 hours.

[0082] In this way, the judgment module (410) determines that recharging is necessary when either of the two judgment criteria is met, thereby maintaining the pressure state of the upper mattress (200) at an appropriate level in response to both a situation of rapid pressure drop and a situation of gradual leakage.

[0083] The supply control module (420) is a control unit that, upon receiving a recharge need determination signal from the determination module (410), executes a series of steps including temporarily suspending pressure control of the lower mattress (100), supplying air to the upper mattress (200), closing the shut-off valve (310), and resuming pressure control of the lower mattress (100).

[0084] The first operation performed by the supply control module (420) is the pressure control stop of the lower mattress (100).

[0085] Since the lower mattress (100) is constantly connected to the air supply system (300) and is under active control by the controller (400), if the shut-off valve (310) is opened in this state, the lower mattress (100) and the upper mattress (200) share the same air supply path, and thus the pressure control between the two mattresses can interfere with each other. At this time, active control refers to feedback control in which the controller (400) compares the internal air pressure of each air cell (110) with the target pressure in real time and repeatedly adjusts the air supply and exhaust of the air supply system (300) to maintain the pressure of the air cell (110) close to the target value.

[0086] To prevent this, the supply control module (420) switches the control signal of the supply line (320) toward the lower mattress (100) to a stop state before opening the shut-off valve (310), so that the pressure control of the lower mattress (100) can be temporarily suspended during the upper mattress (200) refilling period.

[0087] After the pressure control of the lower mattress (100) is stopped, the supply control module (420) applies an opening signal to the shut-off valve (310). When the shut-off valve (310) is opened, a fluid path from the air supply system (300) to the upper mattress (200) is secured so that air can be supplied to the air cells within the upper mattress (200).

[0088] The supply control module (420) can determine whether the air supply to the upper mattress (200) is complete based on several criteria.

[0089] For example, the supply control module (420) may apply a pressure attainment criterion that determines the supply as complete when the measured value of the pressure sensor (280) reaches a preset target charging pressure (P_set).

[0090] At this time, the target charging pressure (P_set) can be set based on the rated charging pressure of the upper mattress (200), for example, in the range of 105 to 110% of the recharging threshold (P_th) to secure a margin that prevents re-entry into the threshold due to immediate re-leakage after recharging.

[0091] As another example, the supply control module (420) may apply a time-based standard by pre-setting the time for air supply after the shut-off valve (310) is opened, and treating the supply as complete once that time has elapsed. The time-based standard can increase the robustness of the implementation in that it is not affected by the measurement error of the pressure sensor (280).

[0092] When it is determined that the supply is complete, the supply control module (420) applies a closing signal to the shut-off valve (310) to block the fluid path between the air supply system (300) and the upper mattress (200) again. By closing the shut-off valve (310), the upper mattress (200) can recover an independent pressure environment isolated from the air supply system (300), just as it was before recharging.

[0093] After the shut-off valve (310) is closed, the supply control module (420) releases the pressure control stop state of the lower mattress (100) and resumes control.

[0094] Thus, the lower mattress (100) can resume pressure control based on the previous setting value before the pause during the recharging period.

[0095] For example, if recharging occurs during a static nighttime period in which there is no change in the user's posture while sleeping, the lower mattress (100) retains the previous control settings, so it can return to a normal control state immediately upon resumption, and the user may not feel any change in the bed's behavior due to recharging.

[0096] In another example, if recharging occurs immediately after the user wakes up and the mattress load is removed, the upper mattress (200) is filled with air to the target charging pressure in a load-free state, the shut-off valve (310) is closed, and then pressure control of the lower mattress (100) is resumed so that the charging state for the next use can be secured in advance.

[0097] Hereinafter, the operation flow of the system of the present invention is explained by exemplifying a situation in which the pressure of the upper mattress (200) gradually decreases during the night period after the user has slept for a long time.

[0098] After sleep begins, the shut-off valve (310) that opens and closes the air supply path to the upper mattress (200) remains in a closed state, and the upper mattress (200) disperses body pressure as the air filled inside is redistributed from the air cell compressed by the user's body weight to the adjacent air cell. At this time, the dispersion of body pressure is achieved by the self-flow of the air filled inside the upper mattress (200) without the intervention of the air supply system (300).

[0099] As long as the shut-off valve (310) remains closed, the internal air pressure of the upper mattress (200) is not affected by external supply fluctuations, so the pressure environment of the upper mattress (200) can be maintained independently even while real-time pressure control of the lower mattress (100) is being performed.

[0100] For example, if the reference filling pressure of the upper mattress (200) is set to 2.0 kPa at the time of sleep initiation, the internal air pressure of the upper mattress (200) can be maintained independently at the 2.0 kPa level regardless of the pressure control operation of the lower mattress (100) as long as the closed state of the shut-off valve (310) is maintained.

[0101] As sleep progresses, fine permeation of air molecules through the air cell material accumulates, causing the internal air pressure of the upper mattress (200) to gradually decrease.

[0102] For example, a situation can be assumed in which the internal air pressure of the upper mattress (200) decreases from 2.0 kPa to 1.8 kPa at the time when 6 to 8 hours have passed since the onset of sleep.

[0103] The determination module (410) continuously receives the measurement value of the pressure sensor (280) and compares it with the recharge threshold (P_th), and immediately upon detecting the point at which the measurement value drops below the recharge threshold (P_th), determines that recharging is necessary and transmits a recharge start signal to the supply control module (420). At this time, the recharge threshold (P_th) may be set to a range of 85 to 95% of the reference charging pressure.

[0104] In the above example, when the recharge threshold (P_th) is set to 1.8 kPa, which is 90% of the standard charging pressure of 2.0 kPa, the pressure sensor (280) is installed in a representative air cell inside the upper mattress (200) to measure the internal air pressure of the entire upper mattress (200) as a representative value, and the judgment module (410) detects the point in time when the measurement value received from the pressure sensor (280) drops to less than 1.8 kPa and determines that recharging is necessary.

[0105] Since the pressure sensor (280) is installed directly inside the upper mattress (200) to measure the internal air pressure of the air cell in real time, the judgment module (410) determines the need for recharging before the user feels a decrease in body pressure, thereby ensuring that the body pressure distribution performance during sleep is continuously maintained.

[0106] Upon receiving the recharge start signal, the supply control module (420) switches the control signal of the supply line (320) toward the lower mattress (100) to a stop state before opening the shut-off valve (310).

[0107] By stopping the control signal of the supply line (320) directed to the lower mattress (100) by the supply control module (420), a situation in which the pressure control of the lower mattress (100) and the upper mattress (200) interferes with each other during the recharging period can be prevented.

[0108] Since the air cell (110) of the lower mattress (100) maintains a sealed structure even when pressure control is temporarily suspended, the support pressure of the lower mattress (100) can be preserved without significant fluctuation during the recharging period.

[0109] For example, if the air cell (110) of the lower mattress (100) is maintained at 3.0 kPa, the 3.0 kPa can be substantially maintained by the sealing structure of the air cell (110) during the 10 to 30 second pause period from when the supply control module (420) stops control until the shut-off valve (310) closes.

[0110] After the pressure control stop of the lower mattress (100) is completed, the supply control module (420) applies an opening signal to the shut-off valve (310).

[0111] When the shut-off valve (310) is opened, a fluid path from the air supply system (300) to the upper mattress (200) is secured, and air supply to the air cells of the upper mattress (200) begins.

[0112] The supply control module (420) determines that the supply is complete when the measurement value of the pressure sensor (280) reaches the target charging pressure (P_set), and applies a closing signal to the shut-off valve (310) to switch the upper mattress (200) back to a segregated state.

[0113] The target charging pressure (P_set) can be set to a range of 105 to 110% of the recharge threshold (P_th), and in the above example, when it is set to approximately 1.9 kPa, which corresponds to 106% of the recharge threshold (P_th) of 1.8 kPa, the supply control module (420) closes the shut-off valve (310) when the measurement of the pressure sensor (280) reaches 1.9 kPa.

[0114] By closing the shut-off valve (310), the upper mattress (200) can be re-isolated with a pressure margin that can prevent the situation of re-entering the recharge threshold (P_th) within a short time, even if micro-permeability resumes immediately after recharging.

[0115] After the shut-off valve (310) is closed, the supply control module (420) releases the pressure control stop state of the lower mattress (100) and resumes control.

[0116] Since the lower mattress (100) maintains the target pressure setting value of 3.0 kPa prior to stopping, the lower mattress (100) can return to a normal control state as soon as the supply control module (420) resumes control.

[0117] In the above example, the total time required from the start of recharging to the closing of the shut-off valve (310) and the resumption of control of the lower mattress (100) can be completed in 10 to 30 seconds, so that the pressure distribution performance of the upper mattress (200) can be restored without hindering the continuity of sleep.

[0118] Thus, the system of the present invention enables continuous operation in which the pressure of the upper mattress (200) is automatically replenished without the user being aware of the recharging operation while sleeping, and the lower mattress (100) maintains the same support pressure throughout the recharging period.

[0119] In summary, the system of the present invention provides the characteristic that the upper mattress (200) is normally isolated from the air supply system (300), thereby allowing the independent pressure environments of the lower mattress (100) and the upper mattress (200) to coexist without mutual interference, and that even during recharging, the pressure control of the lower mattress (100) is temporarily suspended and air is selectively replenished only to the upper mattress (200), thereby recovering the body pressure distribution performance of the upper mattress (200) while substantially maintaining the support pressure state of the lower mattress (100).

[0120] FIG. 3 is a conceptual diagram illustrating the connection structure of a plurality of clusters, check valves, and throttling parts formed on the upper mattress of the present invention.

[0121] As previously explained, the air cells of the upper mattress (200) can be implemented with the same size as the air cells of the lower mattress (100). Since the upper mattress (200) is a layer that comes into direct contact with the user's body, if the size of the air cells is large, the body pressure in the local area where the body weight is applied may not be sufficiently distributed to adjacent air cells and may be concentrated in that air cell. As a result, pressure may be excessively concentrated in a specific area, leading to a possibility of blood circulation disorders or bedsores.

[0122] To solve this, as can be seen from FIG. 3, the upper mattress (200) may have a structure specialized for distributing body pressure.

[0123] First, the air cells of the upper mattress (200) can be composed of microcells (210).

[0124] In the present invention, the term "microcell" refers to a small air cell with a diameter of 30 to 80 mm.

[0125] That is, unlike the air cells (110) of the lower mattress (100) which are configured with a relatively large volume for the purpose of supporting the load of the entire mattress, the microcells (210) of the upper mattress (200) are intended to finely follow the curvature of the user's body and increase the contact points per unit area, thereby dispersing body pressure concentrated in local areas over a wide area.

[0126] If the diameter of the microcell (210) is less than 30 mm, the internal volume of the air cell is too small, making it difficult to secure sufficient cushioning characteristics, and if it exceeds 80 mm, the ability to follow the curvature of the body is reduced, which may reduce the effect of suppressing localized body pressure concentration.

[0127] Specifically, the upper mattress (200) may include a plurality of clusters (220) and connect adjacent clusters (220) to two independent passages, a first passage (240) and a second passage (260), wherein a check valve (250) is installed in the first passage (240) and a throttling section (270) is installed in the second passage (260).

[0128] A cluster (220) means a group of multiple microcells (210) connected to each other by a connecting channel (230) as a single unit.

[0129] Since the microcells (210) within the cluster (220) are connected to each other through the communication channel (230), when the user's body weight is concentrated on a specific microcell (210) within the cluster (220), the air from that microcell (210) can be rapidly redistributed to adjacent microcells (210) within the same cluster (220) through the communication channel (230).

[0130] The reason for not operating the microcells (210) individually but grouping them into a cluster (220) is to structurally control the response speed and range of body pressure distribution.

[0131] In other words, if the entire microcell (210) is configured as a single communication space, the pressure is uniformly distributed across the upper mattress (200), making it difficult to provide concentrated support to specific parts of the body; conversely, if the microcell (210) is completely isolated, local body pressure cannot be dispersed and may remain concentrated in the microcell (210).

[0132] That is, by grouping the microcells (210) into clusters (220), the pressure inside the clusters (220) is rapidly dispersed, and between the clusters (220), the air flow is controlled by the first connecting path (240) and the second connecting path (260), thereby achieving a structural balance in which the overall subsidence is suppressed.

[0133] At this time, it is possible to have a structure in which adjacent clusters (220) in the upper mattress (200) are connected by two independent passages, a first passage (240) and a second passage (260), wherein a check valve (250) is installed in the first passage (240) and a throttling section (270) is installed in the second passage (260).

[0134] If the clusters (220) are connected by only one flow path, the flow path will have only one of the characteristics of unidirectional rapid flow and bidirectional slow flow, making it difficult to simultaneously achieve local pressure relief and overall subsidence suppression.

[0135] To solve this, a structure may be adopted in which the clusters (220) are connected in parallel by two paths, the first path (240) and the second path (260).

[0136] The check valve (250) installed in the first connecting path (240) allows air to flow rapidly in only one direction from the cluster (220) where the pressure peak occurred to the adjacent cluster (220), thereby serving to quickly relieve the local pressure peak.

[0137] The check valve (250) may have a structure that opens only when the inlet pressure exceeds a preset cracking pressure (P_crk) to allow air to pass in one direction, and automatically closes when the inlet pressure drops below the cracking pressure (P_crk).

[0138] The specific implementation form of the check valve (250) can be applied in various ways.

[0139] For example, a ball check valve structure can be applied in which a ball elastically supported by a spring is pressed against a seat to block the flow path, and when the inlet pressure exceeds the cracking pressure (P_crk), the ball compresses the spring and separates from the seat to open the flow path. As another example, a duckbill check valve structure can be applied in which a flexible film bends due to the inlet pressure to open the flow path.

[0140] The cross section (270) installed in the second connecting path (260) can serve to suppress overall subsidence by limiting the flow rate so that air between the clusters (220) moves smoothly in both directions, thereby allowing pressure changes to be slowly transmitted to the entire upper mattress (200).

[0141] The cross-section (270) may have a structure that locally reduces the cross-section of the second connecting path (260) to provide resistance to air flow, and may be formed to have a cross-section of the path that is narrower than that of the connecting path (230) to limit the speed of air movement between clusters (220).

[0142] The implementation form of the constriction section (270) can be applied in various ways. For example, a structure that provides flow resistance by locally narrowing a section of the flow path can be applied, and as another example, a structure that limits the flow rate by inserting a diaphragm having a predetermined fine opening into the flow path can be applied.

[0143] In this way, by operating the unidirectional rapid flow by the check valve (250) and the bidirectional slow flow by the throttling section (270) in parallel, the two requirements of local pressure relief and overall subsidence suppression can be achieved simultaneously while separated on the time axis.

[0144] At this time, the structure in which the supply line (320) is connected to the air cell of the upper mattress (200) can be implemented in various forms.

[0145] For example, a structure may be applied in which the supply line (320) is connected to one specific cluster (220) among a plurality of clusters (220), in which case the air supplied during recharging may be sequentially distributed from the cluster (220) to adjacent clusters (220) through the check valve (250) of the first connection path (240) and the throttling section (270) of the second connection path (260).

[0146] As another example, a structure may be applied in which the supply line (320) is simultaneously connected to each of the multiple clusters (220) through a manifold. In this case, air is supplied simultaneously to all clusters (220) during recharging, so that uniform recharging can be achieved regardless of the directional arrangement of the check valves (250) between the clusters (220).

[0147] In this way, the upper mattress (200) can simultaneously achieve local body pressure relief and overall subsidence suppression by combining fine body pressure tracking at the microcell (210) level, rapid pressure redistribution within the cluster (220), and parallel flow control of the check valve (250) and the throttling section (270) between the clusters (220).

[0148] The previously described throttling section (270) serves to gently restrict air flow between clusters (220), and the magnitude of the flow resistance and pressure response characteristics may vary depending on the specific structure of the throttling section (270).

[0149] If the flow resistance of the cross-section (270) is excessively small, air movement between clusters (220) occurs rapidly, which may reduce the overall subsidence suppression effect. Conversely, if the flow resistance is excessively large, pressure equilibrium between clusters (220) is not achieved, and pressure imbalance between clusters (220) may accumulate during long-term use.

[0150] Considering this, it is possible to define the structure of the bridge section (270) more specifically.

[0151] Specifically, the constriction section (270) can be implemented as either an orifice or a capillary having a channel narrower than the connecting channel (230).

[0152] An orifice is an opening structure that locally reduces a specific cross-section of a flow path, and flow resistance can be determined by the diameter and thickness of the opening.

[0153] The orifice is advantageous for mass production application because the manufacturing process is simplified, as flow resistance can be set simply by adjusting the size of the opening during thermal fusion or high-frequency welding in the molding process of air cell sheets.

[0154] For example, by designing the diameter of the orifice to be less than one-third of the equivalent diameter of the connecting channel (230), it is possible to secure a sufficiently large air movement time constant between clusters (220) compared to the time constant inside the cluster (220).

[0155] A capillary is a tubular structure with a very small inner diameter and extended in the longitudinal direction, and flow resistance is determined by the ratio of the inner diameter to the length.

[0156] Capillaries can be applied in cases where precise time constant control is required, as they allow for fine adjustment of flow resistance by adjusting the length, and thus offer a higher degree of design freedom for resistance values ​​compared to orifices. For example, a structure can be applied in which a capillary with an inner diameter of 0.3 to 0.7 mm is configured with a length of 10 to 50 mm to adjust the pressure equilibrium time between clusters (220) to the level of tens of seconds.

[0157] By having both the orifice and the capillary have a cross-section of the flow path narrower than the connecting flow path (230), it is possible to keep the air flow velocity between the clusters (220) sufficiently low compared to the flow velocity inside the clusters (220).

[0158] Thus, a time separation characteristic is structurally secured in which pressure fluctuations due to changes in the user's body weight are quickly resolved within the cluster (220) and gradually transmitted between the clusters (220), thereby enabling the simultaneous achievement of local body pressure relief and overall subsidence suppression.

[0159] FIG. 4 is a conceptual diagram illustrating the state of air flow from a cluster located in the waist-corresponding area of ​​the present invention toward surrounding clusters.

[0160] The check valve (250) described above allows air to flow in only one direction between clusters (220). If the opening direction of the check valve (250) is not specified, the air in the area where the pressure peak is concentrated may not be effectively dispersed to the surroundings, and a situation may occur where air returns to that area due to reverse flow.

[0161] To solve this, the check valve (250) may be positioned to open from the cluster (220) of the corresponding area where body load is concentrated within the upper mattress (200) toward the surrounding cluster (220).

[0162] The corresponding areas where body weight is concentrated may vary depending on the user's body type and sleeping position. For example, in the supine position, the lumbar and occipital regions are the main areas of weight concentration, while in the lateral position, weight tends to be concentrated in the shoulder and pelvic regions.

[0163] The check valve (250) can be positioned to open from the cluster (220) located in the body load concentration area toward the adjacent cluster (220).

[0164] By setting the opening direction of the check valve (250) to face outward from the cluster (220) of the load concentration area, a flow is formed in which air is discharged unidirectionally through the check valve (250) to an adjacent cluster (220) when a pressure peak occurs in the cluster (220) of the load concentration area. On the other hand, the backflow of air from the adjacent cluster (220) into the load concentration area is suppressed by the closing of the check valve (250), thereby simultaneously mitigating the pressure peak in the load concentration area and maintaining support stability.

[0165] For example, if the check valve (250) is positioned to open from the cluster (220) of the waist corresponding area toward the cluster (220) of the shoulder corresponding area and the pelvis corresponding area, the pressure peak concentrated in the cluster (220) of the waist corresponding area while the user is sleeping in a supine position is distributed through the check valve (250) toward the cluster (220) of the shoulder and pelvis corresponding area.

[0166] At this time, since the shut-off valve (310) remains closed, the air filled inside the upper mattress (200) is not leaked out and is only redistributed between the clusters (220), and as the air is dispersed and maintained in adjacent clusters (220) while backflow to the waist area is blocked, a continuous body pressure relief effect on the waist area is secured.

[0167] When the shut-off valve (310) is opened during recharging, air is supplied from the air supply system (300) to the upper mattress (200). At this time, since the arrangement direction of the check valve (250) is set to face outward from the cluster (220) of the load concentration area, a flow can be formed in which the recharging air first flows into the cluster (220) of the load concentration area and then is sequentially distributed to adjacent clusters (220) through the check valve (250).

[0168] When the shut-off valve (310) is closed after recharging is complete, the upper mattress (200) is switched back to an isolated state, and the check valve (250) resumes the pressure distribution operation while blocking backflow to the load concentration area.

[0169] Additionally, the check valve (250) may have a structure that opens to discharge air to an adjacent cluster (220) when the inlet air pressure exceeds a preset cracking pressure (P_crk), and automatically closes when the inlet air pressure drops below the cracking pressure (P_crk).

[0170] Here, the cracking pressure (P_crk) is the minimum pressure difference at which the check valve (250) begins to open, and can be determined by the spring stiffness of the check valve (250) or the elastic modulus of the thin film.

[0171] The cracking pressure (P_crk) can be set, for example, by adjusting the spring constant or thin film thickness during the design phase of the check valve (250), and after manufacturing is complete, it can be verified by applying pressure to the inlet side in stages and measuring the pressure value at which the check valve (250) begins to open.

[0172] Due to these cracking pressure (P_crk) characteristics, the air pressure inside the cluster (220) of the load concentration area does not reach the cracking pressure (P_crk) due to temporary minute load changes caused by changes in the user's posture or breathing, so the check valve (250) does not open, and the check valve (250) opens only when an actual body pressure peak occurs, allowing the operation of selectively dispersing air to adjacent clusters (220) to be performed.

[0173] For example, if the cracking pressure (P_crk) of the check valve (250) installed in the cluster (220) of the waist corresponding area is appropriately set, the check valve (250) is opened at the time when the body pressure peak concentrated in the waist area exceeds the cracking pressure (P_crk), and air is discharged to the cluster (220) of the shoulder and pelvis corresponding area, thereby relieving the local body pressure in the waist area.

[0174] After the body pressure peak is relieved, the check valve (250) is closed so that the cluster (220) of the waist corresponding area recovers stable support pressure, thereby allowing the effect of improving the stability of spinal alignment during sleep to be expected.

[0175] In summary, by positioning the opening direction of the check valve (250) so as to be directed from the cluster (220) of the body load concentration area toward an adjacent cluster (220), air is selectively dispersed only when a substantial body pressure peak occurs and backflow is blocked, thereby ensuring the support stability of the load concentration area.

[0176] Furthermore, in a structure where the unidirectional discharge characteristic of the check valve (250) and the slow bidirectional flow of the throttling section (270) operate in parallel, the body pressure peak in the load concentration area is quickly relieved, while the situation where the relieved pressure flows backward and impairs the sense of support is suppressed, thereby simultaneously promoting spinal alignment stability and body pressure distribution performance according to the user's sleeping posture.

[0177] The judgment module (410) described above determines whether recharging is necessary based on the measurement value of the pressure sensor (280), but if the specific trigger condition for the judgment is not clearly defined, it may be difficult to make a timely judgment that corresponds to both gradual and rapid pressure drops.

[0178] For example, if only pressure-based judgment is applied, in situations where the pressure drop is gradual, such as the micro-permeation of air molecules through the air cell material, it may take a long time for the measured value to reach the recharge threshold, which may delay the recharge timing; conversely, if only cycle-based judgment is applied, even if a faster-than-expected pressure drop occurs, recharge may not begin until the set cycle has elapsed, resulting in a period where body pressure distribution performance is degraded.

[0179] To resolve this, the determination module (410) may include a trigger determination unit (411) that determines that recharging is required if at least one of the cases where the measured value of the pressure sensor (280) falls below a preset recharging threshold and a preset recharging cycle has elapsed.

[0180] FIG. 5 is a flowchart illustrating the process of determining whether recharging is necessary and recharging the upper mattress according to the present invention.

[0181] The trigger determination unit (411) receives the measurement value of the pressure sensor (280) in real time and compares it with the recharge threshold (P_th), and tracks the time elapsed since the last recharge point and compares it with the recharge cycle. When either of the two conditions is satisfied, it determines that recharging is necessary and transmits a recharge start signal to the supply control module (420).

[0182] In relation to the pressure-based trigger, the trigger determination unit (411) can determine that recharging is required as soon as it detects that the measurement value of the pressure sensor (280) drops below the recharging threshold (P_th).

[0183] For example, when the reference charging pressure is 2.0 kPa and the recharging threshold (P_th) is set to 1.8 kPa, if the measurement value of the pressure sensor (280) drops below 1.8 kPa, the trigger determination unit (411) can detect that time as a recharging trigger and transmit a recharging start signal to the supply control module (420).

[0184] In a situation where air leakage from the air cell proceeds relatively quickly, the pressure-based trigger can function as an immediate response means to rapid pressure changes, in that the trigger judgment unit (411) detects the pressure drop in a timely manner and recharging can be initiated before the body pressure distribution performance deteriorates.

[0185] In relation to the period-based trigger, the trigger determination unit (411) internally tracks the elapsed time based on the time of the last recharge completion and can determine that recharge is needed regardless of the measurement value of the pressure sensor (280) when the preset recharge cycle has elapsed.

[0186] For example, if the recharge cycle is set to 24 hours, the trigger determination unit (411) may have a structure that transmits a recharge start signal at the time when 24 hours have elapsed since the last recharge was completed. During nighttime sleep, the pressure drop due to the fine permeation of air molecules through the air cell material is minimal, so it may be difficult to detect the need for recharge in a timely manner using only a pressure-based trigger; in this case, a cycle-based trigger may operate independently to take on the role of transmitting a recharge start signal.

[0187] Since the two trigger conditions operate independently and recharging can be initiated when either one is satisfied first, it is possible to maintain the pressure state of the upper mattress (200) at an appropriate level in response to both situations where the pressure drop rate is fast and situations where it is gradual.

[0188] In this way, by having the trigger judgment unit (411) independently perform at least one of pressure-based judgment and cycle-based judgment, the advantage is secured that recharging can be initiated at a time before the pressure drop of the upper mattress (200) affects the body pressure distribution performance, regardless of the air leakage rate of the air cell or the usage environment.

[0189] The trigger determination unit (411) described above detects the point when the pressure measurement value drops below the recharge threshold (P_th) or the recharge cycle elapses as a recharge trigger, but since these two conditions are based only on whether the pressure has dropped and the elapsed time, there is a limitation in that they do not reflect how quickly the current pressure drop is progressing.

[0190] For example, if the pressure drop rate increases rapidly even before the measurement value of the pressure sensor (280) reaches the recharge threshold (P_th), the need for recharging cannot be determined based on the current conditions alone, and recharging is delayed until the measurement value reaches the recharge threshold (P_th), which may result in a period where the body pressure distribution performance is degraded.

[0191] To resolve this, the trigger determination unit (411) may further include a reduction rate calculation part (411a) that calculates the reduction rate over time of the measurement value of the pressure sensor (280), and a priority calculation part (411b) that calculates the recharge priority based on the reduction rate and determines whether recharge is necessary.

[0192] The reduction rate calculation part (411a) stores the measurement values ​​collected from the pressure sensor (280) at preset sampling intervals as a time series and performs an operation to calculate the amount of pressure reduction per unit time, i.e., the pressure reduction rate (v), based on the stored measurement values.

[0193] The method for calculating the pressure reduction rate (v) can be implemented in various forms.

[0194] For example, a moving average derivative method can be applied to calculate the pressure reduction rate (v) by calculating the moving average of the previous N measurements and then dividing the difference between the current moving average and the previous moving average by the sampling interval.

[0195] As another example, a method based on the least squares method can be applied to perform linear regression on multiple measurements collected within a preset time interval and calculate the slope of the regression line as the pressure reduction rate (v).

[0196] The regression method tends to provide more stable results compared to the moving average derivative method in that it can increase the accuracy of calculating the pressure reduction rate (v) by averaging the influence of measurement noise.

[0197] The pressure reduction rate (v) calculated by the reduction rate calculation part (411a) is transmitted to the priority calculation part (411b) and used to calculate the recharge priority.

[0198] The priority calculation part (411b) calculates the recharge priority (R) through the following mathematical formula 1 based on the pressure reduction rate (v) received from the reduction rate calculation part (411a) and the current measurement value of the pressure sensor (280), and can determine that recharge is required if the calculated recharge priority (R) exceeds a preset priority threshold.

[0199] Mathematical formula 1.

[0200]

[0201] Here, R is the recharge priority, ΔP is the difference between the recharge threshold and the pressure sensor measurement, P_th is the recharge threshold, v is the rate of decrease over time of the pressure sensor measurement, and v_ref is the reference pressure decrease rate.

[0202] Mathematical formula 1 consists of the sum of a first term reflecting the degree of pressure deficit and a second term reflecting the rate of pressure reduction.

[0203] The first term, tanh(ΔP / P_th), is a pressure deficit contribution indicating how close the current pressure is to the recharge threshold (P_th).

[0204] Since the tanh function has a saturation characteristic that increases monotonically from 0 to 1 as the input value increases, as ΔP increases, the first term converges to 1 and acts in a direction that increases the recharge priority (R).

[0205] When the current pressure is higher than the recharge threshold (P_th) and ΔP is negative, the first term has a negative value and serves to lower the recharge priority (R), and when the current pressure reaches the recharge threshold (P_th), ΔP = 0 and the contribution of the first term becomes 0.

[0206] The second term, (1 - e^(-v / v_ref)), is the reduction rate contribution that converges to 1 as the pressure reduction rate increases.

[0207] When the pressure reduction rate (v) is equal to the reference pressure reduction rate (v_ref), the second term is approximately 0.632, and when the pressure reduction rate (v) reaches twice the reference pressure reduction rate (v_ref), the second term rises to approximately 0.865.

[0208] Thus, even when the current pressure has not yet reached the recharge threshold (P_th), if the pressure reduction rate (v) increases rapidly, the recharge priority (R) may exceed the priority threshold, and recharge may be initiated early.

[0209] As a numerical example for Equation 1, assume a case where the recharge threshold (P_th) is set to 1.8 kPa and the reference pressure reduction rate (v_ref) is set to 0.1 kPa / hr.

[0210] In a gentle leakage situation where the current measurement of the pressure sensor (280) is 1.85 kPa and the pressure reduction rate (v) is 0.05 kPa / hr, ΔP = 1.8 - 1.85 = -0.05 kPa, so the first term is tanh(-0.028) = approximately 0.028 and the second term is 1 - e^(-0.5) = approximately 0.393, which corresponds to R = approximately 0.365.

[0211] On the other hand, in a situation where the pressure reduction rate (v) increases rapidly to 0.2 kPa / hr at the same measured value of 1.85 kPa, the first term remains approximately -0.028, but the second term rises to 1 - e^(-2) = approximately 0.865, reaching R = approximately 0.837.

[0212] As such, even in the same situation where the current pressure has not reached the recharge threshold (P_th), the recharge priority (R) varies significantly depending on the difference in the pressure reduction rate (v). Therefore, if the priority threshold is set to, for example, 0.8, it is possible to provide a selective response in which recharge is not initiated in a gradual leakage situation, but is initiated early in a rapid leakage situation.

[0213] Below, Example 1, to which a recharge priority judgment based on mathematical formula 1 is applied, and Comparative Example 1, to which a pressure threshold judgment alone is applied, are compared.

[0214] The common conditions were set to a reference charging pressure of 2.0 kPa, a recharge threshold (P_th) of 1.8 kPa, and a reference pressure reduction rate (v_ref) of 0.1 kPa / hr.

[0215] The experimental scenario applied a condition in which a gradual leakage section with a pressure drop rate (v) of 0.05 kPa / hr was maintained until 2 hours after the onset of sleep, and then the pressure drop rate (v) rapidly increased to 0.2 kPa / hr due to a micro-defect in the air cell joint at 2 hours after the onset of sleep.

[0216] At 2 hours into sleep, the measurement of the pressure sensor (280) is 1.9 kPa, which has not yet reached the recharge threshold (P_th) of 1.8 kPa.

[0217] <Example 1>

[0218] A trigger determination unit (411) includes a reduction rate calculation part (411a) and a priority calculation part (411b) to calculate a recharge priority (R) according to mathematical formula 1, and applies a configuration that determines that recharge is needed when the recharge priority (R) exceeds a priority threshold of 0.8.

[0219] The reduction rate calculation part (411a) calculates the pressure reduction rate (v) at 2 hours after the onset of sleep as 0.2 kPa / hr and transmits it to the priority calculation part (411b).

[0220] The priority calculation part (411b) calculates the recharge priority (R) as follows according to mathematical formula 1.

[0221] Since ΔP = 1.8 - 1.9 = -0.1 kPa, the first term is tanh(-0.1 / 1.8) = tanh(-0.056) = approximately -0.056, and the second term is calculated as 1 - e^(-0.2 / 0.1) = 1 - e^(-2) = approximately 0.865, so R = approximately -0.056 + 0.865 = approximately 0.809.

[0222] Since the calculated recharge priority (R) 0.809 exceeds the priority threshold of 0.8, the trigger determination unit (411) determines that recharging is required at 2 hours after the onset of sleep and transmits a recharge start signal to the supply control module (420).

[0223] <Comparative Example 1>

[0224] A configuration was applied in which the trigger determination unit (411) does not include a reduction rate calculation part (411a) and a priority calculation part (411b), and determines that recharging is necessary only when the measured value of the pressure sensor (280) drops below the recharging threshold (P_th).

[0225] At the point 2 hours after sleep begins, the measurement value of the pressure sensor (280) is 1.9 kPa, and since it has not reached the recharge threshold (P_th) of 1.8 kPa, the trigger determination unit (411) does not transmit a recharge start signal at that time.

[0226] Since it takes approximately 0.5 hours for the measured value to reach 1.8 kPa from 1.9 kPa while the pressure reduction rate (v) is 0.2 kPa / hr, the trigger determination unit (411) determines that recharging is required at 2.5 hours after the onset of sleep.

[0227] When comparing the above-described Example 1 with Comparative Example 1, the recharging start time in Example 1 is advanced by about 30 minutes compared to Comparative Example 1, and during the 30-minute period in which recharging is delayed in Comparative Example 1, the internal air pressure of the upper mattress (200) continuously decreases from 1.9 kPa to 1.8 kPa, resulting in a period in which the body pressure distribution performance is reduced.

[0228] In contrast, in Example 1, recharging is initiated as soon as a rapid increase in the pressure reduction rate (v) is detected, and the internal air pressure of the upper mattress (200) is replenished at a level of 1.9 kPa, so sleep can be continued without a period in which the body pressure distribution performance is reduced.

[0229] In summary, the recharge priority (R) determination based on mathematical formula 1 has an advantage over the pressure threshold determination alone in that it detects the rapid pressure reduction situation that cannot be detected by the pressure threshold determination alone at an early stage, thereby securing conditions under which recharge can be initiated without a decrease in body pressure distribution performance.

[0230] In addition, the trigger judgment unit (411) described above determines whether recharging is necessary based on the recharging threshold (P_th). If the pressure reduction rate (v) increases rapidly while the recharging threshold (P_th) is fixed, the internal air pressure of the upper mattress (200) may continue to decrease during the time required from the time of recharging determination until the time of recharging completion, when the supply control module (420) temporarily stops pressure control of the lower mattress (100) and opens the shut-off valve (310) to replenish air to the upper mattress (200).

[0231] That is, in a situation where the pressure reduction rate (v) is high, the internal air pressure of the upper mattress (200) may already have dropped deeper below the recharge threshold (P_th) at the time recharge begins, so a situation may occur where it is difficult to sufficiently suppress the deterioration of body pressure distribution performance with only the fixed recharge threshold (P_th).

[0232] To resolve this, the trigger judgment unit (411) may further include a threshold correction part (411c) that increases the recharge threshold (P_th) when the pressure reduction rate (v) exceeds a preset reference reduction rate and reflects this in the determination of whether recharge is necessary.

[0233] The configuration and operation of the reduction rate calculation part (411a) have been explained previously, so a redundant explanation is omitted.

[0234] The threshold correction part (411c) compares the pressure reduction rate (v) received from the reduction rate calculation part (411a) with a preset reference reduction rate, and if the pressure reduction rate (v) exceeds the reference reduction rate, it increases the recharge threshold (P_th) and reflects this in the determination of whether recharge is necessary by the trigger judgment part (411).

[0235] The reason the threshold correction part (411c) raises the recharge threshold (P_th) is to compensate in advance for the additional decrease in internal air pressure of the upper mattress (200) during the time required from the time of recharge determination to the time of recharge completion in a situation where the pressure reduction rate (v) is high.

[0236] That is, the higher the pressure reduction rate (v), the higher the recharge threshold (P_th) is set to induce recharge to begin at an earlier time, thereby ensuring that the air pressure inside the upper mattress (200) at the time of recharge completion is maintained at a level higher than that required for body pressure distribution.

[0237] The method for calculating the adjusted recharge threshold (P_th') by the threshold correction part (411c) can be implemented in various forms.

[0238] For example, a structure can be applied to proportionally increase the recharge threshold (P_th) based on a value obtained by normalizing the product of the pressure reduction rate (v) and the estimated time required for recharge to the reference pressure. Alternatively, as another example, a structure can be applied in which the magnitude range of the pressure reduction rate (v) is divided into multiple stages, and a correction coefficient corresponding to each stage is pre-set and added to the recharge threshold (P_th) in stages.

[0239] For example, when the pressure reduction rate (v) exceeds the reference reduction rate while the reference charging pressure is 2.0 kPa and the preset recharging threshold (P_th) is 1.8 kPa, the threshold correction part (411c) can adjust the adjusted recharging threshold (P_th') upward, for example, to 1.85 kPa, so that the trigger determination unit (411) determines that recharging is required when the measurement value of the pressure sensor (280) drops below 1.85 kPa.

[0240] Thus, even in situations where the pressure reduction rate (v) is high, the internal air pressure of the upper mattress (200) at the time of recharging completion can be maintained at a level higher than that required for body pressure distribution.

[0241] In this way, the threshold correction part (411c) dynamically adjusts the recharge threshold (P_th) according to the pressure reduction rate (v), thereby preventing the air pressure inside the upper mattress (200) at the time of recharge completion from falling below the level required for body pressure distribution even in the event of a sudden leakage, and a judgment structure that actively responds to changes in leakage rate that are difficult to handle with only a fixed recharge threshold (P_th) can be secured.

[0242] The above-described threshold correction part (411c) increases the recharge threshold (P_th) when the pressure reduction rate (v) exceeds the reference reduction rate, but if the amount of adjustment does not reflect the magnitude of the pressure reduction rate (v) and the time during which pressure control of the lower mattress (100) is stopped during the recharge period, it may be difficult to accurately compensate for the pressure drop that occurs during the actual recharge time.

[0243] To solve this, it is preferable for the threshold correction part (411c) to adjust the recharge threshold (P_th) by reflecting the pressure reduction rate (v) and the pressure control pause time (T_pause) of the lower mattress (100) together.

[0244] Figure 6 is a graph illustrating the state in which the recharge threshold is adjusted according to the pressure reduction rate and pressure control pause time of the present invention.

[0245] Specifically, the threshold correction part (411c) can calculate the adjusted recharge threshold (P_th') through the following mathematical formula 2.

[0246] Mathematical formula 2.

[0247]

[0248] (Here, P_th' is the adjusted recharge threshold, P_th is the preset recharge threshold, v is the rate of decrease over time of the pressure sensor's measurement, T_pause is the time during which pressure control of the lower mattress (100) is paused by the supply control module (420), and P_ref is the reference pressure.)

[0249] Mathematical formula 2 takes the structure of calculating an adjusted recharge threshold (P_th') by multiplying a preset recharge threshold (P_th) by a correction coefficient based on the tanh function.

[0250] The correction factor of mathematical formula 2 is composed of [1 + tanh(v · T_pause / P_ref)], and the input value of the tanh function is the value obtained by normalizing the product of the pressure reduction rate (v) and the pressure control stop time (T_pause) of the lower mattress (100) to the reference pressure (P_ref).

[0251] The product of the pressure reduction rate (v) and the pressure control pause time (T_pause) may correspond to the expected pressure drop that further decreases during the recharging period, and can be converted into a dimensionless input value by dividing it by the reference pressure (P_ref).

[0252] To explain the function characteristics, the tanh function has an output value of 0 when the input value is 0, so the correction factor corresponds to 1, and thus P_th' = P_th, so the recharge threshold may not be adjusted.

[0253] As the pressure reduction rate (v) increases or the pressure control pause time (T_pause) becomes longer, the input value of the tanh function increases, and the correction factor can rise to a value between 1 and 2, and accordingly, the adjusted recharge threshold (P_th') can be raised up to a level up to twice the preset recharge threshold (P_th).

[0254] In addition, due to the saturation characteristics of the tanh function, the correction factor does not exceed 2 even if the input value becomes very large, so even in situations where the pressure reduction rate (v) becomes extremely large, the adjusted recharge threshold (P_th') rises excessively, and the situation where unnecessary recharge is repeated can be suppressed.

[0255] As a numerical example of Equation 2, assume a case where the recharge threshold (P_th) is set to 1.8 kPa, the reference pressure (P_ref) to 2.0 kPa, and the pressure control pause time (T_pause) to 20 seconds (= approximately 0.0056 hours). When the pressure reduction rate (v) is 0.1 kPa / hr, the input value of the tanh function is 0.1 × 0.0056 / 2.0 = approximately 0.00028, which is very small and the correction factor approaches 1, so P_th' = approximately 1.800 kPa and the recharge threshold is not practically adjusted.

[0256] On the other hand, if the pressure reduction rate (v) increases rapidly to 1.0 kPa / hr, the input value increases to 1.0 × 0.0056 / 2.0 = approximately 0.0028, so P_th' = approximately 1.805 kPa is adjusted upward, allowing recharging to begin at an earlier time.

[0257] As such, mathematical formula 2 precisely adjusts the recharge threshold by reflecting the pressure reduction rate (v) and the pressure control pause time (T_pause) together, thereby ensuring that the air pressure inside the upper mattress (200) at the time of recharge completion is maintained at a level above that required for body pressure distribution, and structurally prevents a situation where the correction amount becomes excessively large due to the saturation characteristics of the tanh function.

[0258] Below, Example 2, to which a threshold correction based on mathematical formula 2 is applied, and Comparative Example 2, to which only a fixed recharge threshold is applied, are compared.

[0259] Common conditions were set to a reference charging pressure of 2.0 kPa, a recharge threshold (P_th) of 1.800 kPa, a reference pressure (P_ref) of 2.0 kPa, and a pressure control pause time (T_pause) of 20 seconds (= approximately 0.0056 hours). The experimental scenario applied a situation in which the pressure drop rate (v) reached 2.0 kPa / hr due to rapid leakage at the air cell joint.

[0260] <Example 2>

[0261] The threshold correction part (411c) applies a configuration that calculates the adjusted recharge threshold (P_th') by applying mathematical formula 2.

[0262] The threshold correction part (411c) calculates the input value of the tanh function according to Equation 2 as v · T_pause / P_ref = 2.0 × 0.0056 / 2.0 = approximately 0.0056, and applies tanh(0.0056) = approximately 0.0056 to calculate the recharge threshold adjusted to P_th' = 1.8 × [1 + 0.0056] = approximately 1.810 kPa.

[0263] The trigger determination unit (411) can determine that recharging is required when the measured value of the pressure sensor (280) drops to less than 1.810 kPa and transmit a recharging start signal to the supply control module (420).

[0264] Afterwards, during the T_pause 20 seconds when the supply control module (420) stops the pressure control of the lower mattress (100), the internal air pressure of the upper mattress (200) is further reduced by about 0.011 kPa at a rate of reduction of 2.0 kPa / hr, so that the internal air pressure at the time of opening the shut-off valve (310) is about 1.810 - 0.011 = about 1.799 kPa, which can be maintained at a level close to the recharge threshold (P_th) of 1.800 kPa.

[0265] <Comparative Example 2>

[0266] A configuration was applied that does not include a threshold correction part (411c) and only applies a fixed recharge threshold (P_th) of 1.800 kPa.

[0267] The trigger determination unit (411) can determine that recharging is necessary when the measured value of the pressure sensor (280) drops to less than 1,800 kPa and transmit a recharging start signal to the supply control module (420).

[0268] Afterwards, during T_pause 20 seconds, the internal air pressure of the upper mattress (200) is further reduced by about 0.011 kPa at a rate of 2.0 kPa / hr, so that at the time the shut-off valve (310) is opened, the internal air pressure is about 1.800 - 0.011 = about 1.789 kPa, and recharging can be initiated in a state where it is reduced by 0.011 kPa below the recharging threshold (P_th) of 1.800 kPa.

[0269] When comparing the above-described Example 2 and Comparative Example 2, the internal air pressure of the upper mattress (200) at the time of opening the shut-off valve (310) in Example 2 is approximately 1.799 kPa, which is close to the recharge threshold (P_th), whereas in Comparative Example 2, recharge is initiated at approximately 1.789 kPa, which is 0.011 kPa lower than the recharge threshold (P_th), so a period in which the body pressure distribution performance is reduced until the recharge is completed may occur.

[0270] In summary, the threshold correction based on mathematical formula 2 can have an advantage in that it structurally compensates for the additional pressure drop during the T_pause period by reflecting the pressure reduction rate (v) and the pressure control pause time (T_pause) to pre-adjust the recharge threshold, thereby allowing the air pressure inside the upper mattress (200) at the start of recharge to be maintained close to the level required for body pressure distribution.

[0271] As explained above, the configuration and operation of the stacked air cell-based selective rechargeable mattress system according to the present invention have been described and drawn in the above description and drawings; however, this is merely an example, and the concept of the present invention is not limited to the above description and drawings. It is understood that various changes and modifications are possible within the scope of the technical concept of the present invention. Explanation of the symbols

[0272] 100: Lower mattress 110: Air cell 200: Upper Mattress 210: Microcell 220: Cluster 230: Chimney Euro 240: First connection path 250: Check valve 260: Second Link 270: Bridge Section 280: Pressure sensor 300: Air supply system 310: Shut-off valve 320: Supply line 400: Controller 410: Judgment Module 411: Trigger Judgment Unit 411a: Reduction Rate Calculation Unit 411b: Priority Calculation Part 411c: Threshold Correction Part 420: Supply control module

Claims

Claim 1 A mattress system characterized by comprising: a lower mattress including a plurality of air cells, wherein the lower mattress is stacked on the lower mattress and includes a plurality of air cells and a pressure sensor; an air supply system connected to the upper mattress and the lower mattress via a supply line, wherein the supply line connected to the upper mattress is connected via a shut-off valve; and a controller having a determination module that determines whether recharging is required based on a measurement value of the pressure sensor, and a supply control module that, upon determining recharging, temporarily suspends pressure control of the lower mattress, opens the shut-off valve to supply air from the air supply system to the upper mattress, and after supply is completed, closes the shut-off valve and resumes pressure control of the lower mattress. Claim 2 A mattress system according to claim 1, wherein the air cell of the upper mattress is a microcell having a diameter of 30 to 80 mm, and the upper mattress comprises a plurality of clusters including a plurality of microcells connected by a communication channel, a check valve installed in a first connecting channel connecting adjacent clusters, and a constricting member installed in a second connecting channel connecting adjacent clusters. Claim 3 A mattress system according to claim 2, wherein the above-mentioned throttling part is one of an orifice having a flow path narrower than the above-mentioned connecting flow path and a capillary. Claim 4 A mattress system according to claim 2, wherein the check valve is positioned to open from a cluster located in a corresponding area where the user's body weight is concentrated in the upper mattress toward a surrounding cluster, and wherein air filled in the upper mattress flows in one direction from the cluster in the corresponding area toward the surrounding cluster while the shut-off valve is closed. Claim 5 A mattress system according to claim 1, wherein the determination module includes a trigger determination unit that determines that recharging is required when at least one of the cases where the measured value of the pressure sensor falls below a preset recharging threshold and when a preset recharging cycle has elapsed. Claim 6 In claim 5, the trigger determination unit further comprises a reduction rate calculation part that calculates a reduction rate over time of the measured value of the pressure sensor, and a priority calculation part that calculates a recharge priority based on the reduction rate through the following mathematical formula 1 and determines that recharge is required when the recharge priority exceeds a preset priority threshold, characterized in that the matrix system is further comprising: mathematical formula 1. (Here, R is the recharge priority, ΔP is the difference between the recharge threshold and the pressure sensor measurement, P_th is the recharge threshold, v is the rate of decrease of the pressure sensor measurement over time, and v_ref is the reference pressure decrease rate) Claim 7 A mattress system according to claim 5, wherein the trigger determination unit comprises a reduction rate calculation part that calculates a reduction rate over time of the measured value of the pressure sensor, and a threshold correction part that increases the recharge threshold when the reduction rate exceeds a preset reference reduction rate and reflects this in the determination of whether recharge is necessary. Claim 8 In claim 7, the above threshold correction part is characterized by adjusting the recharge threshold through the following mathematical formula 2 based on the above reduction rate and the reference pressure reduction rate, in a mattress system. Mathematical formula 2. (Here, P_th' is the adjusted recharge threshold, P_th is the preset recharge threshold, v is the rate of decrease over time of the pressure sensor measurement, T_pause is the time during which pressure control of the lower mattress is temporarily paused by the supply control module, and P_ref is the reference pressure)

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