WO2006104277A1 - Bed occupancy state detection method - Google Patents

Abstract

Some preferred embodiments of the invention provide a bed occupancy state detection method capable of correctly detecting a bed occupancy state of a care recipient. The method includes a first comparison step of comparing at least one of parameters consisting of a prescribed parameter Ps and a prescribed parameter PL with a previously set first threshold.

Description

DESCRIPTION

BED OCCUPANCY STATE DETECTION METHOD

This application claims priority to Japanese Patent

Application No. 2005-103851 filed on March 31, 2005, and U.S. Provisional Application No. 60/668,600 filed on April 6, 2005, the entire disclosures of which are incorporated herein by reference in their entireties.

Cross Reference to Related Applications

This application is an application filed under 35 U. S. C. §lll(a) claiming the benefit pursuant to 35 U. S. C. §119(e)(l) of the filing date of U . S . Provisional Application No .60/668,600 filed on April 6, 2005, pursuant to 35 U. S. C. §lll(b).

Technical Field

The present invention relates to a bed occupancy state detection method for detecting a bed occupancy state of a care recipient (including a patient; hereinafter simply referred to as "care recipient " ) on a platform of a bed, such as , e.g., the occupancy state of the care recipient on the bed, the care recipient's body movement for getting out of the bed, the care recipient's position on the platform of the bed, the level/degree of the care recipient ' s body motion on the platform, or the type of the care recipients' body motion on the platform. The present invention also relates to a bed occupancy state detection apparatus, and a bed occupancy state monitoring system for monitoring a bed occupancy state of a care recipient .

Background Art

As a method for detecting a bed occupancy state of a care recipient on a platform of a bed, such as, e.g., whether or not the care recipient is occupying the bed, or the care recipient's position on the platform of the bed, the following methods are known .

In the method disclosed by Japanese Patent No. 3,098,997 and Japanese Patent No. 3,529,332, a load applied to each of front, rear, right and left legs of a bed is detected, and the center-of-gravity position of the care recipient on the bed platform is detectedbasedon the loads. Then, basedon this center-of-gravity position, themoving distance, the motion speed, the number ofmotions, etc., of the care recipient on the bed platform are calculated to thereby detect the bed occupancy state of the care recipient .

Furthermore, Japanese Unexamined Laid-open Patent Publication No.2000-105884 discloses amethodfor detectingwhether a care recipient is occupying the bed or whether a care recipient has got out of the bed based on a load detection output voltage from a load detector which detects the load applied to each leg portion of the bed.

In the mean time, in order to correctly grasp the activity state of a care recipient on a bed platform, it is necessary to improve the detection accuracy of the bed occupancy state of the care recipient .

According to conventional bed occupancy state detection methods, however, since the discrimination of the bed occupancy state of the care recipient is performed by comparing a parameter value using the center-of-gravity position of the care recipient which increases/decreases continuously at a fixed rate and a predetermined threshold, the detection accuracy is not so good at the vicinity of the threshold. Thus, it was difficult to correctly detect the bed occupancy state of the care recipient .

The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. Indeed, certain features of the invention may be capable of overcoming certain disadvantages, while still retaining some or all of the features , embodiments , methods , and apparatus disclosed therein.

Other objects and advantages of the present invention will be apparent from the following preferred embodiments.

Disclosure of Invention

The preferred embodiments of the present invention have been developed in view of the above-mentioned and/or other problems in the related art . The preferred embodiments of the present invention can significantly improve upon existing methods and/or apparatuses .

Among otherpotential advantages, some embodiments can provide a bed occupancy state detection method capable of detecting a bed occupancy state of a care recipient correctly.

Among otherpotential advantages , some embodiments can provide a bed occupancy state detection apparatus which can be preferably used for the detection method.

Among otherpotential advantages , some embodiments can provide a bed occupancy state monitoring system.

To attain the aforementioned objects, the preferred embodiments of the present invention provide the following means.

[1] Abed occupancy state detectionmethod, comprising a first comparison step of comparing at least one of parameters consisting of a parameter P₅ given by the following expression (1) _D Ai (Zi + Bi) , A∑(Z2+B2) ... _m ^{HS ~} 1- ^■((ZZi1 ++ BBi1)) W 1-(ZZ22++BB22)) where

W2+W4

Z2 =

W1 + W2+W3 + W4 AK A2 : Any constant number and a parameter P_L given by the following expression (2)

_D Aa(Z3+ B3) , A4(Z4+B4) ,,,

^{PL "} 1-(Z3+ B3) 1-(Z4+ B4) where

A3, A4 : Any constant number

with a previously set first threshold, wherein Wl, W2, W3 , and W4 denote a load applied to a right front portion of a platform of a bed, a load applied to a left front portion of the platform, a load applied to a right rear portion of the platform, and a load applied to a left rear portion of the platform, respectively, or strength of a load detecting output signal outputted from a load detection means for detecting the load applied to the right front portion of the platform, strength of a load detecting output signal outputted from a load detection means for detecting the load applied to the left front portion of the platform, strength of a load detecting output signal outputted from a load detection means for detecting the load applied to the right rear portion of the platform, and strength of a load detecting output signal outputted from a load detection means for detecting the load applied to the left rear portion of the platform, respectively, wherein Bi and B₂ denote a constant on an area width from a right end of the platform of the bed and a constant on an area width

from a left end of the platform, respectively, (but 0≤Bi≤0.5 and

0≤B₂≤0.5), and

wherein B₃ and B₄ denote a constant on an area width from a front end of the platform, and a constant on an area width from

a rear end of the platform, respectively, (but 0--.JB₃SSO.5 and 0

≤B₄≤0.5) .

[2] The bed occupancy state detection method as recited in the aforementioned Item 1, wherein, when a value of the at least one of the parameters P₅ and P_L is less than the first threshold as a comparison result at the first comparison step, the method further comprises a second comparison step of comparing at least one of parameters consisting of a parameter M₃ given by the following expression (3)

Ms - -- O⁾

where

P » dPs ^{Ps "} dt t : Time

TS1U TS12 : Clock time

Csi : Any constant number

and a parameter M_L given by the following expression ( 4 )

where p, >■ dPL

^{PL "} dt t : Time

TLI I , TU2 : clock time

CU : Any constant number with a previously set second threshold.

[3] The bed occupancy state detection method as recited in the aforementioned Item 2 , wherein, when a value of the at least one of the parameters M_s and M_L is not larger than the second threshold as a comparison result at the second comparison step, the method further comprises a third comparison step of comparing a parameter U_L given by the following expression (5)

where dPL

PL'= dt t : Time

ΪL2K , TL22 : Clock time

CL2 : Any constant number

with a previously set third threshold.

[4] The bed occupancy state detection method as recited in the aforementioned Item 3, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison step, the method further comprises a first notification step for giving a notification signal.

[5] The bed occupancy state detection method as recited in the aforementioned Item 3 or 4, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison step, the method further comprises a first display step for displaying information according to the comparison result at the third comparison step.

[6] The bed occupancy state detection method as recited in any one of the aforementioned Items 3 to 5 , wherein, when a value of the parameter Ur₁ is larger than the third threshold as a comparison result of the third comparison step, the method further comprises a first transmission step for transmitting information according to the comparison result at the third comparison step.

[7] The bed occupancy state detection method as recited in any one the aforementioned Items 3 to 6 , wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison step, the method further comprises a fourth comparison step for comparing a value of at least one of parameters consisting of a parameter Gs given by the following expression (6)

Gs= Cs3-Ps' ..-(6) where

^HS dt

C S3 : Any constant number

and a parameter G_L given by the following expression (7)

where

PL'= ^dd^Pt^L

C L3 : Any constant number

with a previously set fourth threshold.

[8] The bed occupancy state detection method as recited in the aforementioned Item 7, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fourth threshold as a comparison result at the fourth comparison step, the method further comprises a second notification step for giving a notification signal.

[9] The bed occupancy state detection method as recited in the aforementioned Item 7 or 8, wherein, when a value of the at least one of parameters G_Ξ and G_L is larger than the fourth threshold as a comparison result at the fourth comparison step. the method further comprises a second display step for displaying information according to the comparison result at the fourth comparison step.

[10] The bed occupancy state detection method as recited in any one of the aforementioned Items 7 to 9, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fourth threshold as a comparison result at the fourth comparison step, the method further comprises a second transmission step for transmitting information according to the comparison result at the fourth comparison step.

[11] The bed occupancy state detection method as recited in any one of the aforementioned Items 2 to 10, wherein, when a value of the at least one of parameters M₅ and M_L is larger than the second threshold as a comparison result at the second comparison step, the method further comprises a third notification step for giving a notification signal.

[12] The bed occupancy state detection method as recited in any one the aforementioned Items 2 to 11, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result of the second comparison step. the method further comprises a third display step for displaying information according to the comparison result at the second comparison step.

[13] The bed occupancy state detection method as recited in any one of the aforementioned Items 2 to 12, wherein, when a value of the at least one of parameters M₅ and Mi₁ is larger than the second threshold as a comparison result " at the second comparison step, the method further comprises a third transmission step for transmitting information according to the comparison result at the second comparison step.

[14] The bed occupancy state detection method as recited in any one of the aforementioned Items 2 to 13, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result at the second comparison step, the method further comprises a fifth comparison step for comparing a value of at least one of parameters consisting of a parameter G_s given by the following expression (6)

Gs = Cs3 - Ps' . . - (6) where

_Ps>=ψ

C S³ : Any constant number

and a parameter G_L given by the following expression ( 7 ) G L = C L3 - PL' ^{• • •} (7) where p. >_ dPL

^{PL "} dt

CL3 : Any constant number

with a previously set fifth threshold.

[15] The bed occupancy state detection method as recited in the aforementioned Item 14,

wherein, when a value of the at least one of parameters G₃ and G_L is larger than the fifth threshold as a comparison result at the fifth comparison step,

the method further comprises a fourth notification step for giving a notification signal.

[16] The bed occupancy state detection method as recited in the aforementioned Item 14 or 15,

wherein, when a value of the at least one of parameters G_s and G_L is larger than the fifth threshold as a comparison result at the fifth comparison step,

the method further comprises a fourth display step for displaying information according to the comparison result at the fifth comparison step.

[17] The bed occupancy state detection method as recited in any qne of the aforementioned Items 14 to .16,

wherein, when a value of the at least one of parameters G_s and G_L is larger than the fifth threshold as a comparison result at the fifth comparison step, the method further comprises a fourth transmission step for transmitting information according to the comparison result at the 5 fifth comparison step.

[18] A bed occupancy state detection apparatus, comprising: a load detection means configured to detect a load applied to a right front portion of a platform of a bed;

10 a load detection means configured to detect a load applied to a left front portion of the platform; a load detection means configured to detect a load applied to a right rear portion of the platform; a load detection means configured to detect a load applied 15 to a left rear portion of the platform; and an operation means , wherein the operationmeans includes afirst comparisonportion for comparing at least one of parameters consisting of a parameter P₅ given by the following expression (1)

_p Ai (Zi + Bi) A2(Zz+ B2) . .

^{PS ~} 1-(Z.1 + Bi) 1-(Zz+ Bz) where

„ _ Al , A2 : Any constant number

and a parameter P_L given by the following expression (2) _D A3(Z3+B3) , A4(Z4+ B4) .. ,₂₎

^{PL "} 1- (Z3+Bs) 1-(Z4+ B4) where

A3_N A4 : Any constant number

with a previously set first threshold, wherein Wl , W2 , W3 , and. W4 denote the load applied to the right front portion of the platform of the bed detected by the load detection means , the load applied to the left front portion of the platform detected by the load detection means , the load applied to the right rear portion of the platform detected by the load detection means, and the load applied to the left rear portion of the platform detected by the load detection means, respectively, or strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the right front portion of the platform, strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the left front portion of the platform, strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the right rear portion of the platform, and strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the left rear portion of the platform, respectively, wherein Bi and B₂ denote a constant on an area width from a right end of the platform of the bed, and a constant on an area

width from a left end of the platform, respectively, (but 0≤=Bi ≤ 0 . 5 and 0≤B₂≤ 0 . 5 ) , and

wherein B₃ and B₄ denote a constant on an area width from a front end of the platform of the bed, and a constant on an area

width from a rear end of the platform, respectively, (but 0≤B₃

≤0.5 and 0≤B₄≤0.5).

[19] The bed occupancy state detection apparatus as recited in the aforementioned Item 18, wherein, when a value of the at least one of the parameters Ps and P_L is less than the first threshold as a comparison result at the first comparison portion, the apparatus further comprises a second comparison portion for comparing at least one of parameters consisting of a parameter M₅ given by the following expression (3)

where _Ps>_=- dPs dt t : Time

TS11 _S TS12 : Clock time Csi : Any constant number

and a parameter M_L given by the following expression (4) ML = CLi r^TU2(PL.')²dt (4) . J Tu 1 where dPL

PL'=- dt t : Time

TU1 _N TL12 : Clock time

GLI : Any constant number with a previously set second threshold.

[20] The bed occupancy state detection apparatus as recited in the aforementioned Item 19, wherein, when a value of the at least one of the parameters Ms and M_L is not larger than the second threshold as a comparison result at the second comparison portion, the apparatus further comprises a third comparison portion of comparing at least one of parameters consisting of a parameter U_L given by the following expression (5)

where dPι_

PL'= dt t : Time

TL21 , „ TL22 : Clock time

CL2 : : Any constant number

with a previously set third threshold.

[21] The bed occupancy state detection apparatus as recited in the aforementioned Item 20, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion, the apparatus gives a notification signal.

[22] The bed occupancy state detection apparatus as recited in the aforementioned Item 20 or 21, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion, the apparatus displays information according to the comparison result at the third comparison portion.

[23] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 20 to 22, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion, the apparatus transmits information according to the comparison result at the third comparison portion.

[24] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 20 to 23, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion. the operation means further comprises a fourth comparison portion for comparing a value of at least one of parameters consisting of a parameter G_s given by the following expression (6)

Gs= Cs3-Ps' -..(6) where p,'. dPs

CS3 : Any constant number

and a parameter G_L given by the following expression ( 7 )

G L = C LS - PL' ^• • • (7) where p, >_ dPL

^{PL "} dt

CL3 : Any constant number

with a previously set fourth threshold.

[25] The bed occupancy state detection apparatus as recited in the aforementioned Item 24, wherein, when a value of the at least one of parameters G_s and Gr, is larger than the fourth threshold as a comparison result at the fourth comparison portion,

the apparatus gives a notification signal.

[26] The bed occupancy state detection apparatus as recited in the aforementioned Item 24 or 25, wherein, when a value of the at least one of parameters G_s

and G_L is larger than the fourth threshold as a comparison result at the fourth comparison portion, the apparatus displays information according to the comparison result at the fourth comparison portion.

[27] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 24 to 26, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fourth threshold as a comparison result at the fourth comparison portion, the apparatus transmits information according to the comparison result of the fourth comparison portion.

[28] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 19 to 27, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result at the second comparison portion, the apparatus gives a notification signal.

[29] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 19 to 28, wherein, when a value of the at least one of parameters M₃ and M_L is larger than the second threshold as a comparison result at the second comparison portion, the apparatus displays information according to the comparison result at the second comparison portion. [30] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 19 to 29, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result at the second comparison portion, the apparatus transmits information according to the comparison result at the second comparison portion.

[31] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 19 to 30, wherein, when a value of the at least one of parameters M₃ and M_L is larger than the second threshold as a comparison result at the second comparison portion, the apparatus further comprises a fifth comparison portion for comparing a value of at least one of parameters consisting of a parameter G_s given by the following expression (6)

Gs = Cs3-Ps' --.(6) where

Cs3 : Any constant number

and a parameter G_L given by the following expression ( 7 ) G L = C LS - P L' ^{• • •} (7) where dPL

PL'= dt

CL3 : Any constant number

with a previously set fifth threshold.

[32] The bed occupancy state detection apparatus as recited in the aforementioned Item 31, wherein, when a value of the at least one of parameters G_s and Gr, is larger than the fifth threshold as a comparison result at the fifth comparison portion, the apparatus gives a notification signal.

[33] The bed occupancy state detection apparatus as recited in the aforementioned Item 31 or 32, wherein, when a value of the at least one of parameters G₃ and G_L is larger than the fifth threshold as a comparison result at the fifth comparison portion, the apparatus displays information according to the comparison result of the fifth comparison portion.

[34] The bed occupancy state detection apparatus as recited in any one of the aforementioned Items 31 to 33, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fifth threshold as a comparison result at the fifth comparison portion. the apparatus transmits information according to the comparison result at the fifth comparison portion.

[35] A bed occupancy state monitoring system, comprising: 5 a load detection means configured to detect a load applied to a right front portion of a platform of a bed; a load detection means configured to detect a load applied to a left front portion of the platform; a load detection means configured to detect a load applied 10 to a right rear portion of the platform,- a load detection means configured to detect a load applied to a left rear portion of the platform; an operation means; a notification means; 15 a display means; and a transmission means, wherein the operationmeans includes afirst comparisonportion for comparing at least one of parameters consisting of a parameter Ps given by the following expression (1)

where

_* Al _% A2 : Any constant number

and a parameter P_L given by the following expression (2) ,₂₎

where

A3v A4 : Any constant number

with a previously set first threshold, wherein Wl , W2 , W3 , and W4 denote the load applied to the right front portion of the platform of the bed detected by the load detection means, the load applied to the left front portion of the platform detected by the load detection means , the load applied to the right rear portion of the platform detected by the load detection means, and the load applied to the left rear portion of the platform detected by the load detection means, respectively, or strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the right front portion of the platform, strength of the load detecting output signal outputted from the load detection means for detecting a load applied to the left front portion of the platform, strength of the load detecting output signal outputted from the load detection means for detecting the load applied to the right rear portion of the platform, and strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the left rear portion of the platform, respectively, wherein B₁ and B₂ denote a constant on an area width from a right end of the platform of the bed, and a constant on an area

width from a left end of the platform, respectively, (but 0-≥Bχ ≤ 0 . 5 and 0 ≤B₂≤ 0 . 5 ) ,

wherein B₃ and B₄ denote a constant on an area width from a front end of the bed, and a constant on an area width from a rear

end of the platform, respectively, (but O≤B_3---iθ.5 and 0≤≥B_4--≥0.5) ,

wherein, when a value of at least one of the parameters P₃ and P₁, is less than the first threshold as a comparison result at the first comparison step, the operation means further includes a second comparison portion for comparing at least one of parameters consisting of a parameter M₅ given by the following expression (3)

where

P » dPs ^{Ps ~} dt t : Time

TS1U TS12 : Clock time

Csi : Any constant number

and a parameter M_L given by the following expression ( 4 )

ML = CLi r^TL12(P_L')²dt - -- C⁴⁾ J Tm where p, >- dPL

^{PL "} dt t : Time

Tu i _S TLI2 : Clock time

CU : Any constant number with a previously set second threshold, wherein the notification means is configured to give a notification signal based on a comparison result at the second comparison portion of the operation means, wherein the displaymeans is configured to display information according to the comparison result at the second comparison portion of the operation means , and wherein the transmission means is configured to transmit information according to the comparison result at the second comparison portion of the operation means .

This invention has the following effects.

According to the invention as recited in the aforementioned Item [1] , whether the occupancy position of the care recipient is in a predetermined area on the bed platform can be correctly detected as the bed occupancy state of the care recipient.

According to the invention as recited in the aforementioned Item [2] , whether the body motion of the care recipient is intense can be detected as the bed occupancy state of the care recipient.

According to the invention as recited in the aforementioned Item [3] , whether the care recipient has raised its upper body can be detected as the bed occupancy state of the care recipient/

According to the invention as recited in the aforementioned Item [4], when the bed occupancy state of the care recipient is in a setting range, the state can be reported to a caregiver, a monitoring personnel, etc., by the notification signal.

According to the invention as recited in the aforementioned Item [5], the information on the bed occupancy state of the care recipient can be displayed assuredly.

According to the invention as recited in the aforementioned Item [6], the information on the bed occupancy state of the care recipient can be transmitted to a remote place, a cellular phone, etc.

According to the invention as recited in the aforementioned Item [7], the care recipient ' s motion for getting out of the bed, for example, can detected as the bed occupancy state of the care recipient.

According to the invention as recited in the aforementioned Item [8], when the bed occupancy state of the care recipient is in a setting range, the state can be reported to a caregiver, monitoring personnel, etc., by a notification signal.

According to the invention as recited in the aforementioned Item [9], the information on the bed occupancy state of the care recipient can be displayed assuredly.

According to the invention as recited in the aforementioned Item [10], the information on the bed occupancy state of the care recipient can be transmitted, to a remote place, a cellular phone, etc .

According to the invention as recited in the aforementioned Item [11], when the bed occupancy state of the care recipient is in a setting range, the state can be reported to a caregiver, a monitoring personnel, etc., by the notification signal.

According to the invention as recited in the aforementioned Item [12], the information on the bed occupancy state of the care recipient can be displayed assuredly.

According to the invention as recited in the aforementioned Item [13], the information on the bed occupancy state of the care recipient can be transmitted to a remote place, a cellular phone, etc.

According to the invention as recited in the aforementioned Item [14], the care recipient's motion for getting out of the bed, for example, can detected as the bed occupancy state of the care recipient .

According to the invention as recited in the aforementioned Item [15], when the bed occupancy state of the care recipient is in a setting range, the state can be reported to a caregiver, a monitoring personnel, etc., by the notification signal.

According to the invention as recited in the aforementioned Item [16], the information on the bed occupancy state of the care recipient can be displayed assuredly.

According to the invention as recited in the aforementioned Item [17], the information on the bed occupancy state of the care recipient can be transmitted to a remote place, a cellular phone, etc.

According to the invention as recited in the aforementioned

Items [18] to [34] , a bed occupancy state detection apparatus which can preferably be used for the bed occupancy state detection method according to the invention as recited in any one of the Items [1] to [17].

According to the invention as recited in the aforementioned Item [35], the bed occupancy state of the care recipient can be monitored assuredly at remote locations, etc.

Brief Description of Drawings

The preferred embodiments of the present invention are shown by way of example, and not limitation, in the accompanying figures, in which: Fig. 1 is a schematic perspective view showing a bed occupancy state detection apparatus according to an embodiment of the invention;

Fig. 2 is a plan view showing a platform of a bed used for the detection apparatus;

Fig. 3 is a block diagram of the detection apparatus;

Fig. 4 is a flowchart of the operation means of the detection apparatus ;

Fig. 5 is a graph showing the value of Parameter P_s;

Fig. 6 is a graph showing the value of Parameter M_Ξ;

Fig. 7 is a graph showing the value of Parameter U_L; and

Fig. 8 is a graph showing the value of Parameter G₃.

Best Mode for Carrying Out the Invention

In the following paragraphs, some preferred embodiments of the invention will be described by way of example and not limitation . It should be understood based on this disclosure that various other modifications can be made by those in the art based on these illustrated embodiments.

Now, an embodiment of the invention will be explained with reference to the drawings .

In Fig. 1, the reference numeral "1" denotes a bed occupancy state detection apparatus, and the reference numeral "20" denotes a bed.

The bed 20 is furniture for use in medical facilities, caring facilities (including nursing facilities: hereinafter referred to as "caring facilities"), aged person facilities, ordinary homes, etc. , and has a care recipient platform 21 (hereinafter simply referred to as "platform" or "bed platform") of a square shape, in detail, a rectangular shape, as seen from the top.

For the explanatory purpose, in this specification, as shown in Fig. 2, in the state in which a care recipient (not illustrated) lies down on the platform 21 of the bed 20, the head side of the care recipient is defined as the front side of the platform 21, while the leg side of the care recipient is defined as the rear side of the platform 21.

The bed 20 is equipped with a total of four leg portions, or front right, front left, rear right and rear left leg portions 20a, 20a, 20a and 20a for supporting the platform 21. In this embodiment , each leg portion 20a, 20a, 20a and 20a is provided with a bed moving caster.

On the platform 21 of this bed 20 , as a care recipient ( including a patient), a sick person, a dementia patient, an aged person as well as a healthy person, an infant, etc., lies down in a lying down posture for sleep , rest , medical treatment , medical examination , inspection, etc.

In this invention, the bed 20 is not limited to a bed for sleep or rest, and can be an examination table, an inspection bench, a stretcher, a sofa, etc.

The bed occupancy state detection apparatus 1 of this embodiment is used for detecting the bed occupancy states of the care recipient on the bed platform 21, such as, e.g. , the occupancy of the bed, the motion for getting out of the bed, the occupancy position, the level of body motions, the rolling over, the type of the body motion or its frequency, the occupancy posture of the care recipient on the bed platform 21.

This detection apparatus 1 is equippedwith four load detection means 2, 2, 2 and 2, a control means 3, a first transmission means

5 , an operation means 6 , a notification means 9 , a display means 10, and a second transmission means 11.

The four load detection means 2, 2, 2 and 2 are arranged under the right front leg portion 20a, the left front leg portion 20a, the right rear leg portion 20a, and the left rear leg portion 20a of the bed 20 on the bed installation surface 23, respectively. With this state, each of them detects the load applied to the corresponding right front portion, left front portion, right rear portion, or left rear portion of the bed platform 21. Each load detection means 2, 2, 2 and 2 can be a load cell, etc.

As shown in Fig. 3, the control means 3 has an amplifier 4 for amplifying the outputvoltage as the strengthof the loaddetecting output signal outputted from each load detection means 2, 2, 2 and 2, and executes analog-to-digital conversion of the output voltage

(output signal) amplified by the amplifier 4.

The first transmission means 5 is configured to transmit the digitally-converted output voltage to the operation means 6 via predetermined cable-communication networks or predetermined wireless-communications networks , such as, e.g. , telephone networks , the Internet, cable LANs, and wireless LANs. In this embodiment, it is configured to transmit the digitally-converted output voltage to the operation means 6 via cable-communication networks.

The operation means 6 is constituted by a computer having a CPU, and memories , such as , e.g., a ROM and a RAM, and has an operation portion 7 for calculating the load applied to each of the right front portion, left front portion, right rear portion, and left rear portion of the bed platform 21 , and the value of a predetermined parameter based on the digitally converted output voltage, and a comparison portion 8 for comparing the value of the predetermined parameter calculated by the operation portion 7 with the previously set threshold.

The notification means 9 is configured to give a notification to a nursing person, monitoring personnel, etc. , by notification signals, such as, e.g., an alarm sound or turning on or blinking of a lamp based on the comparison result of the comparison portion 8 of the operation means 6, and has a notification speaker, a notification lamp, etc.

The display means 10 is configured to display the information according to the comparison result of the comparison portion 8 of the operation means 6 on a display of a monitor television, etc. , and has a CRT, a liquid crystal display, etc.

The second transmission means 11 is configured to transmit the information according to the comparison result of the comparison portion 8 of the operation means 6 to a remote location, a cellular phone (including PHS) , etc. , via predetermined cable-communication networks or predetermined wireless-communication networks, such as, e.g. /telephone networks, the Internet, cable LANs , or wireless LANs.

Next, a bed occupancy state detection method using the aforementioned detection apparatus 1 will be explained below.

In a state in which a care recipient is occupying the platform 21 of the bed 20 , the load applied to each of the right front portion, left front portion, right rear portion, and left rear portion of the bed platform 21 is detected by the corresponding load detection means 2. Then, a load detection output voltage outputted from each load detection means 2 is transmitted to the control means 3 via a signal cable 13.

After being amplified by the amplifier 4 of the control means 3, an analog-to-digital conversion of each transmitted output voltage is executed. Then, the digitally converted output voltage is transmitted to the operation means 6 by the first transmission means 5 via predetermined cable-communication networks or predetermined wireless-communication networks, such as , e.g., the signal cable 14, telephone networks, the Internet, cable LANs, or wireless LANs.

Based on the digitally converted output voltage, the load applied to each of the right front portion, left front portion, right rear portion, and left rear portion of the bed platform 21 and a value of a predetermined parameter are calculated by the operation portion 7 of the operation means 6 , and then the value of a parameter is compared with a predetermined threshold by the comparison portion 8. At the operation portion 7, tare processing is performed in advance with a care recipient not occupying the bed platform 21 to thereby calculate the value from which the tare, such as, a weight of the bed 20, is subtracted as a load. Although the comparison portion 8 is not illustrated, it includes the first to fifth comparison portions 8a, 8b, 8c, 8d and 8e. The detailed explanation about the processing performed by this operation means 6 will be explained later.

Based on the comparison result at the comparison portion 8 of the operation means 6 , the notification means 9 gives a warning sound, or calls attention to anursing person, amonitoringpersonnel, etc . , bylighting orblinking of a lamp . Furthermore , the information according to the comparison result at the comparison portion 8 of the operation means 6 is displayed on a display of amonitor television , etc., in real time by a display means 10. Furthermore, the information according to the comparison result at the comparison portion 8 of the operation means 6 is transmitted to a remote location , a cellular phone, etc., by the second transmission means 11 via predetermined cable-communication networks or predetermined wireless-communication networks , such as , e.g. , telephone networks , the Internet, cable LANs, and wireless LANs. Next, the processing to be performed by the operation means 6 of the aforementioned detection apparatus 1 will be explained below.

First, in the operation portion 7 of the operation means 6, the load applied to each of the right front portion, left front portion, right rear portion, and left rear portion of the platform 21 of the bed 20 is calculated. In this specification, as shown in Fig. 2, the load applied to the right front portion of the bed platform 21, the load applied to the left front portion of the bed platform 21, the load applied to the right rear portion of the bed platform 21, and the load applied to the left rear portion of the bedplatform 21 will be referred to as Wl, W2, W3, andW4, respectively. Here , each of Wl , W2 , W3 , and W4 is a value from which the tare , such as, e.g., the weight of the bed 20, is subtracted. In this invention , however, each of Wl , W2 , W3 , and W4 can be a value including the tare .

In this invention, in place of the above, Wl, W2, W3, and W4 can be a load detection output voltage outputted from the load detection means 2 for detecting a load applied to the right front portion of the bed platform 21, a load detection output voltage outputted from the load detection means 2 for detecting a load applied to the left front portion of the bed platform 21, a load detection output voltage outputtedfrom the load detectionmeans 2 for detecting a load applied to the right rear portion of the bed platform 21, and a load detection output voltage outputted from the load detection means 2 for detecting a load applied to the left rear portion of the bed platform 21, respectively, which are signals before calculating each load at the operation portion 7. In this case, if the load detection output voltages outputted from the respective load detection means 2, 2, 2 and 2 are defined as Vl, V2 , V3 , and V4, respectively, the loads Wl, W2, W3 and W4 can be obtained by Wl=alxVl+cl, W2=a2xV2+c2, W3=a3xV3+c3, and W4=a4xV4+c4, wherein al to a4 are previously set constants other than 0 and cl to c4 are previously set constants.

It is preferable that the number of load detections per second by each of the load detection means 2, 2, 2 and 2 is 2 times/second or more, more preferably not less than 4 times/ second but not more than 10,000 times/second. In this invention, however, the number of load detections is not limited to the above range.

As shown in Fig. 2, a constant on an area width dl from a right end of the platform 21 of the bed 20 and a constant on an area width d2 from a left end of the platform 21 are represented by Bl and B2, respectively. However, Bl and B2 should meet the conditions

of O≤Bl≤O .5 and 0≤B2≤0.5 , more preferably 0<Bl<0.2 and 0<B2<0.2 ,

still more preferably 0. KBKO.15 and 0.1<B2<0.15, respectively. Bl and B2 can be B1=B2 or can be B1≠B2. In this invention, however, Bl and B2 are not limited to the aforementioned ranges, and can

be arbitrarily set so long as they meet the conditions of O≤≥Bl ≤ 0 . 5 and 0≤B2≤ 0 . 5 .

Furthermore, a constant on an area width d3 from a front end of the platform 21, and a constant on an area width d4 from a rear end of the platform 21 are represented by B3 and B4, respectively.

However, B3 and B4 should meet the conditions of 0≤B3≤≥0.5 and 0

≤≥B4≤0.5, more preferably 0<B3<0.25 and 0<B4<0.25, still more

preferably 0. l<B3<0.2 and 0. l<B4<0.2 , respectively. B3 and B4 can be B3=B4 or can be B3≠B4. In this invention, however, B3 and B4 are not limited to the aforementioned ranges, and can be arbitrarily

set so long as they meet the conditions of O≤-B3---!θ.5 and 0≤≥B4

≤0.5.

Bl and B2 will be detailed as follows. Bl is a value obtained by dividing the width bl of the area dl from the right end of the bed platform 21 in the widthwise direction of the bed 20 by the full width S of the bed platform 21, i.e., Bl=bl/S. B2 is a value obtained by dividing the width b2 of the area d2 from the left end of the bed platform 21 in the widthwise direction of the bed 20 by the full width S of the bed platform 21, i.e., B2=b2/S.

B3 and B4 will be detailed as follows . B3 is a value obtained by dividing the width b3 of the area d3 from the front end of the bed platform 21 in the longitudinal direction of the bed 20 by the full length L of the bed platform 21, i.e. , B3=b3/L. B4 is a value obtained by dividing the width b4 of the area d4 from the rear end of the bed platform 21 in the longitudinal direction of the bed

20 by the full length L of the bed platform 21, i.e., B4=b4/L.

Each of bl to b4 can be set arbitrarily. For example, it can be set as a fall dangerous area width from each end of the bed platform

21 on the bed platform 21 for the care recipient. In this case, each of bl to b4 is preferably set so as to fall within the range of from 0 to 300 mm, more preferably 100 to 200 mm. In this invention, however, bl to b4 are not limited to the above range", and can be arbitrarily set .

Then, at the operation portion 7 of the operation means 6, as to the parameter P₅ given by the following expression 1

_r. Ai(Zi+Bi) , A2(Z2+B2)

^KS~ 1-(Zi+Bi) 1-CZ2+B2) ^" where

Wi +W3

AK A2 : Any constant number

and the parameter P_L given by the following expression 2,

_p A3(Z3+B3) A4(Z4+ B4) . . . (2)

^{KL ~} I- ^■C(ZZ33++BB33)) ^' 11--((ZZ44++ BB44)) w /hheerree

A3 _s A4 : Any constant number the value in each clock time (time) is calculated.

Al to A4 are arbitrary constants each expressing sensibility, preferably larger than 0. They can meet the conditions of A1=A2 or A1≠A2, and A3=A4 or A3≠A4.

As shown in Fig. 4, at step Sl, at the comparison portion 8 (the first comparison portion 8a), the parameters P₃ and P_L are comparedwiththe correspondingfirst thresholds H_SiandH_Lipreviously set and stored in a memory (not shown), respectively. This step Sl is defined as a "first comparison step."

As a result of this first comparison step Sl, if the value of at least one of the parameters P₅ andP_L is less than the corresponding first threshold, i.e., Ps<H_Si and/or P_L<H_LI, the routine proceeds to Step S2 as "YES."

On the other hand, if the value of both the parameters P₃ and Pr₁is not smaller than the correspondingfirst threshold, respectively,

i.e., Ps^H₃₁ and P_L≥H_Li, the routine returns to "Start" as "NO."

At this first comparison step Sl, it is discriminated whether the occupancy position of the care recipient is in the predetermined area of the bed platform 21. In cases where bl to b4 are set as fall dangerous area widths from each end of the bed platform 21 of the care recipient, for example, on the bed platform 21, and Bl to B4 are constants corresponding to the fall dangerous area widths of the bed platform 21 , respectively, at this first comparison step Sl, it will be discriminated whether the occupancy position of the care recipient is in the fall dangerous area of the bed platform 21. And if at least one of the parameters P₃ and P_L is less than the corresponding first threshold, i.e., P_s<H_Si and/or P_L<H_LI, it is discriminated that the occupancy position of the care recipient is in the fall dangerous area of the bed platform 21.

At Step S2 , as to the parameter M₃ represented by the following expression (3)

where

Ps'= dPs

^' dt t : Time

TS11 , TS12 : Clock time

Csi : Any constant number

and the parameter M_L represented by the following expression (4)

where

t : Time

TLH , TL12 : Clock time

C L1 : Any constant number the operation portion 7 calculates the value of the parameters M₃ and M_L within a set time (i.e. , between the clock times T_Sn to Tsi2» and T_Lii to T_L12) , respectively.

Csi and C_Li are arbitrary constants showing sensibility, preferably larger than 0 , respectively. Theycanmeet the conditions

of CΞI=CLI or CSI≠CLI.

The set time for calculating the value of each parameters M_s and M_L, i.e. , the time from the clock time T_Sn to T₃₁₂ and the time from T_LII to T_LX2 preferably fall within the range of 0.01 to 60 seconds , more preferably 0.1 to 10 seconds, still more preferably 0.2 to 2 seconds. In this invention, however, the set time is not limited to the above, and can be set arbitrarily.

At Step S2, in the comparison portion 8 (the second comparison portion 8b) , the parameters M₃ and M_L are compared with the corresponding second thresholds H₃₂ and H_L2 previously set and stored in a memory (not shown) , respectively. This Step S2 is defined as a "second comparison step."

As a comparison result at this second comparison step S2, if the value of at least one of the parameters M₃ and M_L is larger than the corresponding second threshold, i.e., M_S>H₃₂ and/or M_L>H_L2, the routine proceeds to Steps S7 and S8 as "YES", respectively.

On the other hand, if the value of both parameters M₃ and M_L is not larger than the corresponding second threshold, respectively. i.e. , M_s≤ΪHs₂, and M_L≤≥H_L2, the routine proceeds to Step S3 as "NO.

At this second comparison Step S2 , for example, it is possible to discriminate whether the body motion of the care recipient is intense. That is, if the value of at least one of the parameters

Ms and M_L is larger than the corresponding second threshold, it is discriminated that the body motion of the care recipient is intense.

On the other hand, if the values of both parameters M₅ and M_L are not larger than the corresponding second threshold, respectively, it is discriminated that the body motion of the care recipient is not intense.

At Step S3 , in the operation portion 7 , the value within a

set time ( i . e . , between the clock times T_L2i and T_L2i ) is calculated as to the parameter U₁, expressed by the following expression ( 5 ) .

where p, >_ dPL

t : Time

TL21 _S TL22 : Clock time

C L2 : Any constant number

C_L2 is an arbitrary constant showing sensibility , preferably larger than 0 . The set time for calculating the value of the parameter U_L/ i.e. , the time between the clock time Ti_12x and T_L22, preferably falls within the range of from 0.01 to 60 seconds, more preferably 0.1 to 10 seconds, still more preferably 0.2 to 2 seconds. In this invention, however, the set time is not limited to the above ranges, and can be set arbitrarily.

And this Step S3, in the comparison portion 8 (the third comparison portion 8c) , the parameter U_L is compared with the corresponding third threshold H_L2 previously set and stored in a memory (not shown) . This Step S3 is defined as a "third comparison step."

As a comparison result at this third comparison Step S3, if the value of the parameter U_L is larger than the third threshold, i.e., U_L>H_L3, the routine proceeds to Steps S4 and S5 as "YES," respectively.

On the other hand, if the value of the parameter U_L is not

larger than the third threshold (i.e. , Ui₁=H₁₁₃) , the routine returns

to "Start" as "NO."

At this third comparison step S3, for example, it is possible to discriminate the type of body motion of the care recipient. More concretely, it is possible to discriminate,, for example, whether the care recipient has raised its upper body as the body motion of the care recipient. That is, if the value of the parameter U_L is larger than the third threshold, it is discriminated that the care recipient has raised its upper body for example . On the other hand, if the value of the parameter Ur, is not larger than the third threshold, it is discriminated that the care recipient has not raised the upper body.

At Step S4, the notification means 9 notifies a caregiver (including a nurse), a monitoring personnel, etc., of the bed occupancy state of the care recipient by giving an alarm sound, turning on or blinking a lamp as a notification signal ("first notification step"). Furthermore, the display means 10 displays, for example, information on the bed occupancy state of the care recipient on a display, etc. , inreal time as the information according to the comparison result at the third comparison Step S3 ("first display step" ) . Furthermore, the transmission means 11 transmits, for example, the information on the bed occupancy state of the care recipient to a remote location, a cellular phone, etc., as the information according to the comparison result of the third comparison Step S3 ("first transmission step").

Concretely, in order to notify a caregiver, monitoring personnel, etc. , of the bed occupancy state of the care recipient, e.g. , a state in which a care recipient is going to raise its upper bodyand get out of thebedintentionallyforwarning, thenotification means 9 gives a getting-out-of-bed alarm sound, and/or turns on/blinks a getting-out-of-bed alarm lamp. And the display means 10 also displays the information showing the state in which a care recipient is going to raise its upper body and get out of the bed intentionally. Furthermore, the second transmission means 11 transmits the information that, for example, the care recipient is going to raise the upper body and get out of the bed intentionally to a remote location, a cellular phone , etc . Based on the information notified by the notification means 9 , displayed by the display means 10 , and the information transmitted by the second transmission means 11, a caregiver, etc., can taka a necessary action for the care recipient, e.g., an assistance for getting out of the bed for the care recipient .

At Step S5 , as to the parameter G₅ represented by the following expression (6)

Gs = Cs3 - Ps^? .. - (6) where p > dPs

C S3 : Any constant number

and the parameter G_L represented by the following expression ( 7 )

G L = C LS - P L* ^{• • •} (7) where dPL

PL'= dt

C L3 : Any constant number the operation portion 7 calculates the valued of the parameters Gs and G_L at each clock time (time), respectively.

Cs₃ and C_L3 are arbitrary constants showing sensibility, preferably larger than 0, respectively. They canmeet the conditions of Cs₃=Cr,₃ or Csa^C^.

At Step S5, in the comparison portion 8 (the fourth comparison portion 8d) , the parameters G_s and G_L are compared with the corresponding fourth thresholds H₅₄ and H_L4 previously set and stored in a memory (not shown) , respectively. This Step S5 is defined as a "fourth comparison step."

As a comparison result at this fourth comparison step S5, if the value of at least one of the parameters G_s and Gr, is larger than the corresponding fourth threshold, i.e., G_S>H_S4 and/or Gχ₁>H_L4, the routine proceeds to Step S6 as "YES."

On the other hand, if the value of both parameters G_s and G_L is not larger than the corresponding fourth threshold, respectively,

i.e., Gs≤H_S4, and G_L≤H_L4, the routine returns to "Start" as "NO."

At this fourth comparison Step S4 , for example, it is possible to discriminate whether the care recipient has actually got out of the bed. That is, if the value of at least one of the parameters

G₃ and G_L is larger than the corresponding fourth threshold, it is discriminated that the care recipient has raised its upper body and got out of the bed. On the other hand, if the values of both parameters G_s and G_L are not larger than the corresponding fourth threshold, respectively, it is discriminated that the care recipient has raised its upper body but not yet got out of the bed.

At Step S6, the notification means 9 notifies a caregiver, a monitoring personnel, etc., of the bed occupancy state of the care recipient by giving an alarm sound, or turning on or blinking a lamp as a notification signal ("second notification step").

Furthermore, the displaymeans 10 displays, for example, information on the bed occupancy state of the care recipient on a display, etc. , in real time as the information according to the comparison result at the fourth comparison Step S5 ( "first second notification step" ) . Furthermore, the second transmission means 11 transmits, for example, the information on the bed occupancy state of the care recipient to a remote location, a cellular phone, etc., as the information according to the comparison result at the fourth comparison Step S5 ("second transmission step") .

Concretely, in order to notify a caregiver, monitoring personnel, etc. , of the bed occupancy state of the care recipient, e.g. , a state in which a care recipient has got out of the bed to call attention to them, the notification means 9 gives a getting-out-of-bed alarm sound, and/or turns on/blinks a getting-out-of-bed alarm lamp. And the display means 10 also displays the information showing the state in which a care recipient has got out of the bed. Furthermore, the second transmission means 11 transmits the information that, for example, the care recipient has got out of the bed to a remote location, a cellular phone, etc. Based on the information notified by the notification means 9 , displayed by the display means 10, and the information transmitted by the second transmission means 11, a caregiver, etc., can take a necessary action for the care recipient .

At Step S7, in the same manner as at Step S4, the notification means 9 notifies a caregiver, a monitoring personnel, etc. , of the bed occupancy state of the care recipient by giving an alarm sound, or turning on or blinking a lamp as a notification signal ("third notification step"). Furthermore, the display means 10 displays, for example, information on the bed occupancy state of the care recipient on adisplay, etc. , inreal time as the informationaccording to the comparison result at the second comparison Step S2 ("third display step"). Furthermore, the second transmission means 11 transmits, for example, the information on the bed occupancy state of the care recipient to a remote location, a cellular phone, etc. , as the information according to the comparison result at the second comparison Step S2 ("third transmission step") .

Concretely, in order to notify a caregiver, monitoring personnel, etc. , of the bed occupancy state of the care recipient, e.g. , a state in which the occupancy position of the care recipient is in a fall danger region and the care recipient is in danger of falling off from the bed to call attention to them, the notification means 9 gives a fall alarm sound, and/or turns on/blinks a fall alarm lamp. And-the display means 10 also displays the information showing the state in which the care recipient is in danger of falling off from the bed. Furthermore, the second transmission means 11 transmits the information that, for example, the care recipient is in danger of falling off from the bed to a remote location, a cellular phone, etc. Based on the information notified by the notification means 9, displayed by the display means 10, and the information transmitted by the second transmission means 11, a caregiver, etc., can take a necessary action for preventing the falling of the care recipient .

At Step S8, as to the parameter G_s represented by the following expression (6)

Gs = Cs3 ' Ps' .. . (6) where

^Ps dt

CS3 : Any constant number

and the parameter G_L represented by the following expression ( 7 ) G L = C LS - P L' • • • (7) where

C L3 : Any constant number

the operation portion 7 calculates the valued of the parameters G₃ and G_L at each clock time (time), respectively.

Cs₃ and C_L3 are arbitrary constants showing sensibility, preferably larger than 0 , respectively. They canmeet the conditions

Of CS3 = CL3 Or C_S3≠C_L3 -

At Step S8, in the comparison portion 8 (the fifth comparison portion 8e) , the parameters G₃ and G_L are compared with the

^■ corresponding fifth thresholds H_Ss and H_L5 previously set and stored in a memory (not shown) , respectively. This Step S8 is defined as a "fifth comparison step."

As a comparison result at this fifth comparison step S8, if the value of at least one of the parameters G_s and G_L is larger than the corresponding fifth threshold, i.e., G_S>H_S5 or/and G_L>H_L5, the routine proceeds to Step S9 as "YES."

On the other hand, if the value of both parameters G_s and G_L is not larger than the corresponding fifth threshold, respectively,

i.e.; G_S≤H_S5, and G_L≤H_L5, the routine returns to "Start" as "NO." At this fifth comparison Step S8, for example, it is possible to discriminate whether the care recipient has actually got out of the bed. That is, if the value of at least one of the parameters Gs and G_L is larger than the corresponding fifth threshold, it is discriminated that the care recipient has raised its upper body and got out of the bed. On the other hand, if the values of both parameters G₅ and G_L are not larger than the corresponding fifth threshold, respectively, it is discriminated that the care recipient has not got out of the bed.

At Step S9 , in the same manner as at Step 6, the notification means 9 notifies a caregiver, a monitoring personnel, etc. , of the bed occupancy state of the care recipient by giving an alarm sound, or turning on or blinking a lamp as a notification signal ("fourth notification step"). Furthermore, the display means 10 displays, for example, information on the bed occupancy state of the care recipient on adisplay, etc. , inreal time as the information according to the comparison result at the fifth comparison Step S8 ("fourth display step"). Furthermore, the second transmission means 11 transmits, for example, the information on the bed occupancy state of the care recipient to a remote location, a cellular phone, etc. , as the information according to the comparison result at the fifth comparison Step S8 ("fourth transmission step") .

Concretely, in order to notify a caregiver, monitoring personnel, etc. , of the bed occupancy state of the care recipient, e.g. , a state in which a care recipient has got out of the bed to call attention to them, the notification means 9 gives a getting-out-of-bed alarm sound, and/or turns on/blinks a getting-out-of-bed alarm lamp. And the display means 10 also displays the information showing the state in which a care recipient has got out of the bed. Furthermore, the second transmission means 11 transmits the information that, for example, the care recipient has got out of bed to a remote location, a cellular phone, etc. Based on the information notified by the notification means 9, displayed by the display means 10, and the information transmitted by the second transmission means 11, a caregiver, etc., can take a necessary action for the care recipient.

Thus, the bed occupancy state detection method of this embodiment has the following advantage.

That is, this detection method includes the first comparison step for comparing the value of the parameter of both predetermined parameters P_s and P_L with a predetermined first threshold. Here, since the value of parameters P_s and P_L suddenly changes at predetermined positions among the occupancy positions of the care recipient and does not increase (or decrease) continuously at a constant rate as in a conventional method, it is possible to correctly detect whether the occupancy position of the care recipient is in the predetermined area of the bed platform 21. Concretely, for example, in cases where Bl to B4 are constants regarding the fall dangerous area width of the bed platform 21, respectively, it is possible to correctly discriminate whether the occupancy position of the care recipient is in the fall dangerous area of the bed platform 21.

Furthermore, since this detection method includes the second comparison step S2, it is possible to correctly detect whether the body motion of the care recipient is intense as the bed occupancy state of the care recipient.

Moreover, since this detection method includes the third comparison step S3, it is possible to correctly detect whether the care recipient has raised its upper body as the bed occupancy state of the care recipient.

Moreover, since this detection method includes the first to fourth notification steps, when the bed occupancy state of the care recipient is in the set range , the state can be notified to a caregiver , a monitoring personnel, etc. , by a notification signal (a warning sound, turning on or blinking of a lamp, etc.).

Moreover, since this detection method includes the first to fourth display steps, it is possible to assuredly display the information on the bed occupancy state of the care recipient. Moreover, since this detection method includes the first to fourth transmission steps, it is possible to assuredly transmit the information on the bed occupancy state of the care recipient to a remote location, a cellular phone, etc.

Moreover, since this detection method includes the fourth comparison step S5, it is possible to correctly detect, for example, the motion for getting out of bed of the care recipient as the bed occupancy state of the care recipient.

Moreover, since this detection method includes the fifth comparison step S8, it is possible to correctly detect, for example, the motion for getting out of bed of the care recipient as the bed occupancy state of the care recipient .

The bed occupancy state detection apparatus 1 of this embodiment has the same advantage as the aforementioned detection method.

The bed occupancy state monitoring system according to an embodiment of this invention is equipped with each load detection means 2 , 2 , 2 and 2 in the aforementioned detection apparatus 1 , the first transmissionmeans 5 , the operation portion 7 andcomparison portion 8 of the operation means 6 , the notification means 9 , the display means 10 and the second transmission means 11. Therefore, according to this monitoring system, there are the same advantages as the aforementioned detection method, and the bed occupancy state of the care recipient on the bedplatform 21 can be monitored assuredly at a remote location, etc.

Although an embodiment of this invention is explained above, this invention is not limited to in the aforementioned embodiment, and can be modified variously.

For example, according to this invention, at the first comparison step Sl, only the value of one of the parameters P_s and P_L can be comparedwith a correspondingpreviously set first threshold. Moreover, at the second comparison step S2, only the value of one of parameters M₃ andM₁, can be comparedwith a correspondingpreviously set second threshold. Moreover, at the fourth comparison step S5, only the value of one of parameters G₃ and G_L can be compared with a corresponding previously set fourth threshold. Moreover, at the fifth comparison step S8, only the value of one of parameters G₅ and G_L can be compared with the fifth corresponding threshold set .

Moreover, the bed occupancy state detection apparatus according to the invention can be an apparatus capable of measuring the biological information, such as, e.g., the breathing of the care recipient, or the cardiac beats, as well as the bed occupancy state of a care recipient, or can be an apparatus combined with a biological information measuring device. EXAMPLE

Next, concrete examples of this invention will be described below.

As shown in Fig. 2, a bed 20 in which the full width S of the widthwise direction of the platform 21 was 830 mm, the full length L of the longitudinal direction of the platform 21 was 2,000 mm was prepared. The care recipient's weight was 80 kg.

<Concrete example of parameter P_s>

The width bl and the width b2 of the area dl and the area d2 from the right end and the left end of the bed platform 21 in the widthwise direction of the bed 20 were set to 125 mm, respectively. Therefore, since Bl=bl/S and B2=b2/S, each value of Bl and B2 was 0.15 (15%). Here, in this example, bl and b2 were set as a fall dangerous area width from the right end of the platform 21 for the care recipient on the bed platform 21 and that from the left end of the bed platform 21, respectively. Moreover, Al and A2 were set as 1, respectively.

Fig. 5 is a graph (figure) showing the value of the parameter

Ps when a care recipient moved from the right end of the bed platform 21 to the left end every 2 cm. In this graph, the horizontal axis shows the actual occupancy position of the care recipient on the bed platform 21 in the widthwise direction of the bed 20. In the parameter P_s, A1=A2=1 and Bl=B2=0.15. Moreover, the number of the load detection by each load detection means 2, 2, 2 and 2 was set to 5 times per second.

As shown in Fig.5, in the value of the parameter P₃, by setting the first threshold H_Si to 0 and comparing this P_s with the first threshold H_Si=0 (first comparison Step Sl), it becomes possible to correctly detect whether the occupancyposition of the care recipient is in the set areas dl and d2. That is, in this comparison, if Ps<0, it is possible to correctly detect that the occupancy position of

the care recipient is in the set areas dl and d2 , and if P_s≤≥0, it

is possible to correctly detect that the occupancy position of the care recipient is outside the set areas dl and d2. Therefore, if the widths bl and b2 of the set areas dl and d2 are temporarily set as a fall dangerous area width from the right end of the platform 21 for the care recipient on the bed platform 21 and that from the left end of the platform 21, respectively, to thereby set Bl and B2 as the constants on the fall dangerous area widths of the bed platform 21, respectively, it is possible to correctly detect whether the occupancy position of the care recipient is in the fall dangerous area of the bed platform 21.

In the same manner, as to the value of the parameter P_L, by setting the first threshold H_Li to 0 and comparing the P_L with the first . threshold Hm=O (first comparison Step Sl), it is possible to correctly discriminate whether the occupancy position of the care recipient is in the set areas d3 and d4. That is, in this comparison, if P_L<0, the occupancy position of the care recipient is in a set areas d3 and d4 , it is possible to correctly discriminate that the occupancy position of the care recipient is in the set

areas d3 and d4 , and if P_L=0 , it is possible to correctly discriminate

that the occupancy position of the care recipient is outside the set areas d3 and d4.

<Example of Parameter M_s>

Fig. 6 is a graph (figure) showing the value of parameter M₅ in cases where the care recipient lying on its back at the center of the widthwise direction of the bed platform 21 along the longitudinal direction shook its body by turning over toward the right side and then left side. The center-of-gravity position of the care recipient in the widthwise direction of the bed 20 in the same movement was also detected in accordance with a conventional method. In this graph, the scale of a right-hand side scale of the vertical axis expresses the center-of-gravity position of the care recipient in the widthwise direction of the bed 20 detected by a conventional method.

In this example, the set time for calculating the value of parameter M_s, i.e., the time from the clock time T_Sn to T_Ξi₂, was set to 1 second. It is also set to C₅ i=l and C_Li=l. The movements of the care recipient were as follows. Until about 0 to 4 seconds , although the care recipient was quietly sleeping on this back along the longitudinal direction at the center of the widthwise direction of the bed platform 21, thereafter, it began rolling over toward the right-hand side and the stopped the rolling over movement in 6 to 7 seconds. Then, it rolled over toward the left-hand side, passed the center of the bed platform 21 in about

8 seconds while continuing the rolling over, and stopped the rolling on its back after about 9 seconds. Thereafter, the care recipient continued the violent shaking movements till about 23 seconds.

As shown in Fig. 6, the parameter M_s is quite high in the S/N ratio as compared with the fluctuation of the center-of-gravity position of the care recipient , and fluctuates notably. Therefore, in the value of parameter M₈, by setting the second threshold H_S2 to 400 and comparing with the second threshold H_S2=400 (second comparison Step S2) , it is possible to more accurately discriminate whether the body motion of the care recipient is intense as compared with a conventional method. That is, in this comparison, if M_s>400, it is possible to correctly detect that the body motion is intense,

and if M_s≤400, it is possible to correctly detect that the body

motion is not so intense.

In the same manner,, as to the value of the parameter M_L/ by setting the secondthresholdH_L2 to apredeterminedvalue and comparing the M_L with this second threshold H_L2, it is possible to correctly discriminate whether the body motion of the recipient is intense.

< Example of Parameter U_L>

Fig. 7 is a graph (figure) showing the value of the parameter U_L when the care recipient was sleeping on its back in the longitudinal direction at the center of the widthwise direction of the bed platform 21 has raised its upper body. Moreover, the center-of-gravity position of the care recipient in the longitudinal direction of the bed 20 of the same body motion was also detected according to a conventional method. In this graph, the scale of the right-hand side vertical axis expresses the center-of-gravity position of the care recipient in the longitudinal direction of the bed 20 detected by a conventional method.

In this example, the set time for calculating the value of the parameter U_L, i.e., the time from the clock time T_L2i to T_L22# was set to 1 second. It is also set to C_L2=1.

As shown in Fig. 7, the parameter U_L is quite high in the S/N ratio as comparedwith the movement of the center-of-gravityposition of the care recipient, and fluctuates notably. Therefore, in the value of parameter U_L, by setting the third threshold H_L3 to 2 and comparing the U_L with the third threshold H_L3=2 (third comparison Step_#S3), it is possible to more accurately discriminate whether the care recipient has raised its upper body as compared with a conventional method. That is, in this comparison, if U_L>2, it is possible to correctly detect that the care recipient has raised

its upper body, and if Ur,≤≥2, it is possible to correctly detect

that the care recipient has not raised its upper body.

< Example of Parameter Gs>

Fig. 8 is a graph (figure) showing the value of the parameter Gs in cases where the care recipient has got out of the bed from the left end (or right end) of the bed platform 21. In this movement, it was about 15 seconds when the care recipient has completely got out of the bed. The center-of-gravity position of the care recipient in the widthwise direction of the bed 20 in the same movement was also detected in accordance with a conventional method. In this graph, the Y axis at the right side expresses the center-of-gravity position of the care recipient in the widthwise direction of the bed 20 detected by a conventional method.

In this example, the time dt for calculating the value of parameter G_s was set to 1 second. It is also set to C_S3=1 and C_L3=1.

As shown in Fig.8 , although it is hard to discriminate whether the care recipient has got out of the bed from the fluctuation of the center-of-gravity position of the care recipient by the conventional method, according to the value of the parameter G₃, it is possible to clearly discriminate whether the care recipient has got out of the bed. Therefore, in the value of Parameter G_s, by setting the fourth threshold H₃₄ to 200 and comparing the G_s with the fourth threshold H_S4=200 (fourth comparison Step S5), it is possible to more accurately discriminate whether the care recipient has got out of the bed as compared with a conventional method. That is, in this comparison, if G_s>200, it is possible to correctly detect

that the care recipient has got out of the bed, and if G_s≤≥200, it

is possible to correctly detect that the care recipient has not got out of the bed.

In the same manner, as to the value of the parameter G_L, by setting the fourth thresholdHr,₄ to apredeterminedvalue andcomparing the G_L with this fourth threshold H_L4/ it is possible to correctly discriminate whether the care recipient has got out of the bed.

Industrial applicability

The present invention can be utilized in a bed occupancy state detection method for detecting a bed occupancy state of a care recipient on a platform of a bed, such as, e.g. , the occupancy state of the care recipient on the bed, the care recipient's body movement for getting out of the bed, the care recipient's position on the platform of the bed, the level/degree of the care recipient's body motion on the platform, or the type of the care recipients' body motion on the platform. The present invention also can be utilized in a bed occupancy state detection apparatus , and a bed occupancy state monitoring system for monitoring a bed occupancy state of a care recipient .

While the present invention may be embodied in many different forms , a number of illustrative embodiments are described herein with the understanding that thepresent disclosure is to be considered as providing examples of the principles of the invention. and such examples are not intended to limit the invention to preferred embodiments described herein an/or illustrated herein.

While illustrative embodiments of the invention have been described herein , the present invention is not limited to the various preferred embodiments described herein, but includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations as would be appreciated by those in the art based on the present disclosure. The limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. For example, in the present disclosure, the term "preferably" is non-exclusive andmeans "preferably, but not limited to." In this disclosure and during the prosecution of this application, means-plus-function or step-plus -function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) "means for" or "step for" is expressly recited; b) a corresponding function is expressly recited; and c) structure, material or acts that support that structure are not recited. In this disclosure and during the prosecution of this application, the terminology "present invention" or "invention" may be used as a reference to one or more aspect within the present disclosure. The language present invention or invention should not be improperly interpreted as an identification of criticality, should not be improperly interpreted as applying across all aspects or embodiments (i.e., it should be understood that the present invention has a number of aspects and embodiments), and should not be improperly interpreted as limiting the scope of the application or claims . In this disclosure and during the prosecution of this application, the terminology "embodiment" can be used to describe any aspect, feature, process or step, any combination thereof , and/or anyportion thereof, etc. In some examples, various embodiments may include overlapping features . In this disclosure and during the prosecution of this case, the following abbreviated terminology may be employed: "e.g. " which means "for example; " and "NB" which means "note well. "

Claims

1. Abedoccupancy state detectionmethod, comprising afirst comparison step of comparing at least one of parameters consisting of a parameter P₃ given by the following expression (1)

_m

where

Al _s A2 : Any constant number

and a parameter P_L given by the following expression (2)

_D A3(Z3+BS) , A4(Z4+ B4) _f2s

^PL ~ 1- (Z3+ B3) 1-(Z4+ B4) where

A3_S A4 : Any constant number

with a previously set first threshold, wherein Wl , W2 , W3 , and W4 denote a load applied to a right front portion of a platform of a bed, a load applied to a left front portion of the platform, a load applied to a right rear portion of the platform, and a load applied to a left rear portion of the platform, respectively, or strength of a load detecting output signal outputted from a load detection means for detecting the load applied to the right front portion of the platform, strength of a load detecting output signal outputted from a load detection mean's for detecting the load applied to the left front portion of the platform, strength of a load detecting output signal outputted from a load detection means for detecting the load applied to the right rear portion of the platform, and strength of a load detecting output signal outputted from a load detection means for detecting the load applied to the left rear portion of the platform, respectively, wherein Bi and B₂ denote a constant on an area width from a right end of the platform of the bed and a constant on an area

width from a left end of the platform, respectively, (but O≤aBi

≤0.5 and 0≤-B₂≤0.5), and

wherein B₃ and B₄ denote a constant on an area width from a front end of the platform, and a constant on an area width from

a rear end of the platform, respectively, (but 0≤-B₃≤Ϊ0.5 and 0

≤B₄≤0.5) .

2. The bed occupancy state detection method as recited in claim 1 , wherein, when a value of the at least one of the parameters P₅ and P_L is less than the first threshold as a comparison result at the first comparison step, the method further comprises a second comparison step of comparing at least one of parameters consisting of a parameter M₅ given by the following expression (3) P TS12 , o

Ms = Csi \ (Ps ) dt ^{• • •} (³) «J Tsi i where

^κs dt t : Time

TS11 _* TS12 : Clock time

CS1 : Any constant number

and a parameter M_L given by the following expression (4)

where PL'= ^d d^Pt^L t : Time

TLH , TL12 : Clock time Cu : Any constant number with a previously set second threshold.

3. The bed occupancy state detection method as recited in claim 2 , wherein, when a value of the at least one of the parameters M₃ and M₁, is not larger than the second threshold as a comparison result at the second comparison step, the method further comprises a third comparison step of comparing a parameter U_L given by the following expression (5) UL

where

t : Time

TL21 , , TL22 : Clock time

CL2 : : Any constant number

with a previously set third threshold.

4. The bed occupancy state detection method as recited in claim 3 , wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison step, the method further comprises a first notification step for giving a notification signal.

5. The bed occupancy state detection method as recited in claim 3, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison step, the method further comprises a first display step for displaying information according to the comparison result at a third comparison step.

6. The bed occupancy state detection method as recited in claim 3 , wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result of the third comparison step, the method further comprises a first transmission step for transmitting information according to the comparison result at the third comparison step.

7. The bed occupancy state detection method as recited in claim 3, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison step, the method further comprises a fourth comparison step for comparing a value of at least one of parameters consisting of a parameter G₅ given by the following expression (6)

Gs=Cs3-Ps' -..(6) where

P-'- dPs ^PS~ dt

Cs3 : Anyconstant number

and a parameter G_L given by the following expression (7) G L = C L3 - PL' - .. (7) where

CL3 : Any constant number

with a previously set fourth threshold.

8. The bed occupancy state detection method as recited in claim 7, wherein, when a value of the at least one of parameters G_s and G₁, is larger than the fourth threshold as a comparison result at the fourth comparison step, the method further comprises a second notification step for giving a notification signal.

9. The bed occupancy state detection method as recited in claim 7, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fourth threshold as a comparison result at the fourth comparison step, the method further comprises a second display step for displaying information according to the comparison result at the fourth comparison step.

10. The bed occupancy state detection method as recited in claim 7 , wherein, when a value of the at least one of parameters G_s and G_L is larger than the fourth threshold as a comparison result at the fourth comparison step, the method further comprises a second transmission step for transmitting information according to the comparison result at the fourth comparison step.

11. The bed occupancy state detection method as recited in claim 2 , wherein, when a value of the at least one of parameters M₃ and Mr, is larger than the second threshold as a comparison result at the second comparison step, the method further comprises a third notification step for giving a notification signal.

12. The bed occupancy state detection method as recited in claim 2 , wherein, when a value of the at least one of parameters M₃ and M_L is larger than the second threshold as a comparison result of the second comparison step, the method further comprises a third display step for displaying information according to the comparison result at the second comparison step.

13. The bed occupancy state detection method as recited in claim 2 , wherein, when a value of the at least one of parameters M₅ and M_L is larger than the second threshold as a comparison result at the second comparison step, the method further comprises a third transmission step for transmitting information according to the comparison result at the second comparison step.

14. The bed occupancy state detection method as recited in claim 2, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result at the second comparison step, the method further comprises a fifth comparison step for comparing a value of at least one of parameters consisting of a parameter G₃ given by the following expression (6)

where

Ps'= dPs dt

Cs3 : Any constant number

and a parameter G_L given by the following expression (7)

where

CL3 : Any constant number

with a previously set fifth threshold .

15. The bed occupancy state detection method as recited in claim 14, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fifth threshold as a comparison result at the fifth comparison step, the method further comprises a fourth notification step for giving a notification signal.

16. The bed occupancy state detection method as recited in claim 14, wherein, when a value of the at least one of parameters G_s and Gi₁ is larger than the fifth threshold as a comparison result at the fifth comparison step, the method further comprises a fourth display step for displaying information according to the comparison result at the fifth comparison step.

17. The bed occupancy state detection method as recited in claim 14, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fifth threshold as a comparison result at the fifth comparison step, the method further comprises a fourth transmission step for transmitting information according to the comparison result at the _#fifth comparison step.

18. A bed occupancy state detection apparatus, comprising: a load detection means configured to detect a load applied to a right front portion of a platform of a bed; a load detection means configured to detect a load applied to a left front portion of the platform; a load detection means configured to detect a load applied to a right rear portion of the platform; a load detection means configured to detect a load applied to a left rear portion of the platform; and an operation means , wherein the operation means includes a first comparison portion for comparing at least one of parameters consisting of a parameter P₈ given by the following expression (1)

_Pc . Ai (Zi + Bi) , A2(Z2+B2) . _m ^{HS "} 1-(Zi + Bi) 1-(Z2+ Bz) ^UJ where

Au A2 : Any constant number

and a parameter P_L given by the following expression (2)

_□ A3(Z3+B3) , A4(Z4+BO _n,

^{PL =} 1- (Z3+ BS) 1-(Z4+ B4) ^' where

A3_^ A4 : Any constant number

with a previously set first threshold,

" wherein Wl , W2 , W3 , and W4 denote the load applied to the right front portion of the platform of the bed detected by the load detection means , the load applied to the left front portion of the platform detected by the load detection means, the load applied to the right rear portion of the platform detected by the load detection means, and the load applied to the left rear portion of the platform detected by the load detection means , respectively, ^"or strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the right front portion of the platform, strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the left front portion of the platform, strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the right rear portion of the platform, and strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the left rear portion of the platform, respectively, wherein B₁ and B₂ denote a constant on an area width from a right end of the platform of the bed, and a constant on an area

width from a left end of the platform, respectively, (but O≤≥Bi

≤0.5 and 0≤B₂≤0.5), and

wherein B₃ and B₄ denote a constant on an area width from a front end of the platform of the bed, and a constant on an area

width from a rear end of the platform, respectively, (but 0≤-B₃

≤≥0.5 and O≤B₄≤!θ .5) .

19. The bed occupancy state detection apparatus as recited in claim 18, wherein, when a value of the at least one of the parameters Ps and P_L is less than the first threshold as a comparison result at the first comparison portion, the apparatus further comprises a second comparison portion for comparing at least one of parameters consisting of a parameter Ms given by the following expression (3)

where

^Hs dt t : Time

TS1 U TS12 : Clock time

Csi : Any constant number

and a parameter M_L given by the following expression ( 4 )

ML = CU f^TL12(P!_')²dt -- " C⁴⁾ J TLI I where p, >_ dPL

^{PL ~} dt t : Time

TL11 _S TL12 : Clock time

CL1 : Any constant number with a previously set second threshold.

20. The bed occupancy state detection apparatus as recited in claim 19, wherein, when a value of the at least "one of the parameters M₅ and M_L is not larger than the second threshold as a comparison result at the second comparison portion, the apparatus further comprises a third comparison portion of comparing at least one of parameters consisting of a parameter U_L given by the following expression (5)

UL

where dPL

PL'= dt t : Time

TL21. . Ti_22 : Clock time

CL2 : : Any constant number

with a previously set third threshold.

21. The bed occupancy state detection apparatus as recited in claim 20, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion, the apparatus gives a notification signal.

22. The bed occupancy state detection apparatus as recited in claim 20, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion , the apparatus displays information according to the comparison result at the third comparison portion.

23. The bed occupancy state detection apparatus as recited in claim 20, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion, the apparatus transmits information according to the comparison result at the third comparison portion.

24. The bed occupancy state detection apparatus as recited in claim 20, wherein, when a value of the parameter U_L is larger than the third threshold as a comparison result at the third comparison portion, the operation means further comprises a fourth comparison portionfor comparingavalue of at least one of parameters consisting of a parameter G_s given by the following expression (6)

Gs= Cs3-Ps' -..(6) where

^HS~ dt

C S3 : Any constant number

and a parameter G_L given by the following expression (7) GL = CI_3-PL^J -.-(7) where

P, >_ dPL ^{PL "} dt

CL₃ : Any constant number

with a previously set fourth threshold.

25. The bed occupancy state detection apparatus as recited in claim 24, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fourth threshold as a comparison result at the fourth comparison portion, the apparatus gives a notification signal.

26. The bed occupancy state detection apparatus as recited in claim 24, wherein, when a value of the at least one of parameters G₃ and Gr, is larger than the fourth threshold as a comparison result at the fourth comparison portion, the apparatus displays information according to the comparison result at the fourth comparison portion.

27. The bed occupancy state detection apparatus as recited in claim 24, wherein, when a value of the at least one of parameters G₃ and .Gr, is larger than the fourth threshold as a comparison result at the fourth comparison portion. the apparatus transmits information according to the comparison result of the fourth comparison portion.

28. The bed occupancy state detection apparatus as recited in claim 19, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result at the second comparison portion, the apparatus gives a notification signal.

29. The bed occupancy state detection apparatus as recited in claim 19, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result at the second comparison portion, the apparatus displays information according to the comparison result at the second comparison portion.

30. The bed occupancy state detection apparatus as recited in claim 19, wherein, when a value of the at least one of parameters M_s and M_L is larger than the second threshold as a comparison result at the second comparison portion, the apparatus transmits information according to the comparison result at the second comparison portion.

31. The bed occupancy state detection apparatus as recited in claim 19, wherein, when a value of the at least one of parameters M_s and Mr₁ is larger than the second threshold as a comparison result at the second comparison portion, the apparatus further comprises a fifth comparison portion for comparing a value of at least one of parameters consisting of a parameter G_s given by the following expression (6)

Gs= Cs3-Ps' ..-(6) where

Cs3 : Any constant number

and a parameter G_L given by the following expression (7)

where _p, >_ dPL

CL3 : Any constant number

with a previously set fifth threshold.

32. The bed occupancy state detection apparatus as recited in claim 31, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fifth threshold as a comparison result at the fifth comparison portion,

^• the apparatus gives a notification signal.

33. The bed occupancy state detection apparatus as recited in claim 31, wherein, when a value of the at least one of parameters G₃ and Gi, is larger than the fifth threshold as a comparison result at the fifth comparison portion, the apparatus displays information according to the comparison result of the fifth comparison portion.

34. The bed occupancy state detection apparatus as recited in claim 31, wherein, when a value of the at least one of parameters G_s and G_L is larger than the fifth threshold as a comparison result at the fifth comparison portion, the apparatus transmits information according to the comparison result at the fifth comparison portion.

35. A bed occupancy state monitoring system, comprising: a load detection means configured to detect a load applied to a right front portion of a platform of a bed; a load detection means configured to detect a load applied to a left front portion of the platform; a load detection means configured to detect a load applied to a right rear portion of the platform; a load detection means configured to detect a load applied to a left rear portion of the platform; an operation means ; a notification means,- a display means ; and a transmission means, wherein the operation means includes a first comparison portion for comparing at least one of parameters consisting of a parameter P_s given by the following expression (1)

Al _s A2 : Any constant number

and a parameter P_L given by the following expression ( 2 )

_D _ A3(Z3-i-B3) A4(Z4+ B4) ₍₂₎

^{KL ~} 1-(Z3+Bs) 1-(Z4+ B4) where

A3_S A4 : Any constant number

with a previously set first threshold, wherein Wl, W2 , W3 , and W4 denote the load applied to the right front portion of the platform of the bed detected by the load detection means, the load applied to the left front portion of the platform detected by the load detection means, the load applied to the right rear portion of the platform detected by the load detection means , and the load applied to the left rear portion of the platform detected by the load detection means , respectively. or strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the right front portion of the platform, strength of the load detecting output signal outputted from the load detection means for detecting a load applied to the left front portion of the platform, strength of the loaddetecting output signal outputted fromthe load detection means for detecting the load applied to the right rear portion of the platform, and strength of a load detecting output signal outputted from the load detection means for detecting the load applied to the left rear portion of the platform, respectively, wherein Bi and B₂ denote a constant on an area width from a right end of the platform of the bed, and a constant on an area

width from a left end of the platform, respectively, (but O≤≥Bi

≤0.5 and 0≤B₂≤0.5) ,

wherein B₃ and B₄ denote a constant on an area width from a front end of the bed, and a constant on an area width from a

rear end of the platform, respectively, (but 0Ξ≥B₃≤0.5 and O≤≥

B₄≤0.5) ,

wherein, when a value of at least one of the parameters P₃ and P_L is less than the first threshold as a comparison result at the first comparison step, the operation means further includes a second comparison portion for comparing at least one of parameters consisting of a parameter M₃ given by the following expression (3)

where

^{Ps ~} dt t : Time

TS11 _S TS12 : Clock time

Csi : Any constant number

and a parameter M_L given by the following expression ( 4 )

ML = CLi r^TU2(p_L')²dt ^• " ⁽«⁾ J Tu 1 where

^HL dt t : Time

Tm _S TLI2 : Clock time

Cu : Any constant number with a previously set second threshold, wherein the notification means is configured to give a notification signal based on a comparison result at the second comparison portion of the operation means, wherein the display means is configured to display information according to the comparison result at the second comparison portion of the operation means, and wherein the transmission means is configured to transmit information according to the comparison result at the second comparison portion of the operation means.