Patent Publication Number: US-2004056520-A1

Title: Sitting means having sensing device

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to a sitting means, and particularly relates to a sitting means having sensing device for sensing the sitting posture of an occupant on a sitting means and thereby for encouraging and urging the occupant to have optimum sitting posture.  
       BACKGROUND ART  
       [0002] Generally, a “sitting means” has a substantially horizontal seat member which supports the thighs and pelvis of an occupant and a substantially vertical back member which is vertically positioned above the seat member and is adapted to provide support to the back of the occupant.  
       [0003] Thus, the sitting means, in this specification, indicates any one of the chairs, vehicle seats, airplane seats, benches, sofas, folding chairs, beach chairs, wheel chairs, school seat-desks, church pews, auditorium and stadium seats, sitting parts of exercise apparatuses, and the like.  
       [0004] For convenience, the term “chair” or “seat” is sometimes used to representatively denote all these types of sitting means.  
       [0005] There have been numerous chairs that are especially designed for the chair occupants to have optimum sitting postures. Typically, the seat members and back members of these chairs are well designed to match the curve of the human trunk.  
       [0006] In actuality, almost all the chairs in the markets are well designed to have proper configurations, based on the medical study, to support the vertebral column and pelvis of the occupant.  
       [0007] What is important is not the chair itself.  
       [0008] It is the very sitting posture of the occupant in a chair that matters.  
       [0009] No matter what good structures and functions a chair may have, it is useless unless a person sitting in the chair uses it in right and good sitting posture.  
       [0010] It is well known that faulty sitting posture in the chair is the most common cause of low back pain and sciatica, and in order to prevent lumbar myalgia it has long been recommended for the occupants to have optimum sitting posture.  
       [0011] Further, it is very important to persons in sedentary occupations who spend long hours or perhaps the entire workday in the chairs to maintain good sitting posture.  
       [0012] Especially, in case of teens and children who grow rapidly and study at home and school everyday, it is of great importance for them to have right sitting posture in the chairs.  
       [0013] When one makes it a habit to sit in a chair in right sitting posture from his/her early days, he/she can have well built straight body, he/she can prevent chronic lumbar myalgia, and he/she can have physiologically erect posture even in his/her old age.  
       [0014] In a broad way, the right sitting posture in a chair is to let the hip closely contact the lower part of the back member and to let the spinal column be so physiologic, erect and static as to maintain the biomechanical, neutral spine position of a person having a normal posture in which muscular balance is maintained.  
       [0015]FIGS. 1 and 2 illustrate the right and faulty sitting postures of a person sitting on the work chair and driving seat, respectively.  
       [0016] The person in the left of FIGS. 1 and 2 tilts his/her upper body part forward and backward, respectively, which inevitably result in excessive movements of the muscles, ligaments and tendons which hold the lumbar vertebrae and sacrum in normal place.  
       [0017] Thus, this protracted muscular stress results in discomfort, strain and fatigue, which effects are obviously dramatic on concentration and productivity in the worker and driver, respectively.  
       [0018] The person in the right of FIGS. 1 and 2 sits in right sitting posture, with the hip contacting the lower part of the back member and the spinal column being in physiological, erect and neutral position, which requires minimal movements of the muscles, ligaments and tendons associated with the spinal and pelvic bones.  
       [0019]FIGS. 3 and 4 schematically depict the pertinent skeletal components of the person shown in the left and right of FIG. 2 in phantom, respectively. The lumbar vertebrae are commonly indicated (L 1 ) through (L 5 ), and are identified as such in the drawings. The letters “(S), (I), (IT), (LSI)” designate the sacrum, ilium, iliac tuberosity, and lumbosacral interspace, respectively.  
       [0020] In FIG. 3, the pelvic and lumbar bones are bridged between the seat member ( 21 ) and back member ( 31 ), which inevitably requires excessive movements of the muscles, ligaments and tendons associated with spinal and pelvic bones. The use of muscles, tendons and ligaments in such a manner over an extended period results in fatigue and pain.  
       [0021] On the other hand, in FIG. 4, the pelvic girdle including ilia (I), sacrum (S), and coccyx (C) is posteriorly and inferiorly positioned to contact the back member ( 31 ), the ischial tuberosities (IT) are firmly supported on the seat member ( 21 ), and the spinal column including lumbar vertebrae (L 1 ) through (L 5 ) are also supported by said back member.  
       [0022] Accordingly, the relative movements among the bones of spine and pelvis, especially the movements between the sacrum (S) and (L 5 ) at the lumbosacral interspace (LSI), are so minimized that one can concentrate on his work without feeling any fatigue or lower back pains.  
       [0023] The word “contact” as used in this specification, of course, merely means that back member ( 31 ) or seat member ( 21 ) touches the skin and the fleshy portions of the body immediately behind the bones such as ilia, sacrum, lumbar vertebrae, thoracic vertebrae, shoulder blades, ribs, thigh bones and so on. Accordingly, in order to let a person have good sitting posture, it is necessary to remind him/her to let his/her hip be so posteriorly and inferiorly positioned that the pelvic girdle including the ilia, sacrum, and coccyx may be posteriorly and infer iorly positioned to contact the lower part of the back member and the ischial tuberosities may be firmly supported on the seat member, and to let his/her spine be erect and straightened in order to maintain the neutral spine position.  
       DESCRIPTION OF THE PRIOR ARTS  
       [0024] In the prior arts, there have never been any devices or methods that encourage, lead, or urge an occupant in a sitting means to have optimum sitting posture by providing a sensing device to a sitting means.  
       OBJECTS OF THE INVENTION  
       [0025] It is therefore an object of the present invention to provide a device and method for an occupant in a sitting means to have optimum sitting posture with his/her pelvis being so posteriorly and inferiorly positioned to contact the back member and the spine being erect and straightened.  
       [0026] It is a further object of the present invention to provide a device and method in combination with a sitting means for an occupant in a sitting means to have optimum sitting posture.  
       [0027] It is still a further object of the present invention to provide a device and method in combination with subsidiaries for sitting means such as covers, mat-type support members, and the like, for an occupant in a sitting means to have optimum sitting posture.  
       [0028] Accordingly, it is the ultimate object of the present invention to provide a device and method which encourages a person to sit in optimum sitting posture such that one can concentrate on his work without feeling any fatigue or lower back pains.  
       [0029] Still a further ultimate object of the present invention is to provide a device and method which leads a person to habitually sit in optimum sitting posture from his/her early days such that; first, he/she can have well built straight body, second, he/she can prevent chronic lumbar myalgia, and third, he/she can have physiologically erect posture even in his/her old age.  
       SUMMARY OF THE INVENTION  
       [0030] The sensing device of the present invention is for a sitting means having seat member and back member, and basically comprises one or a plurality of sensing means, a responding means, a switch part and a microcomputer, which are electrically interconnected to one another.  
       [0031] Said one or a plurality of sensing means are provided to the part(s) of the seat member and/or the back member of a sitting means to which the body of an occupant is contacting when the occupant sits in the sitting means in right sitting posture.  
       [0032] Said sensing means generates/sends a signal to the microcomputer when an occupant sits on the sitting means and contacts said sensing means.  
       [0033] Upon receiving the signal, the microcomputer orders the responding means either to respond or not, according to predetermined program.  
       [0034] Accordingly, when the responding means responds, the occupant, upon recognizing the responding signal, tries to contact all the sensing means in order to stop the response by correcting his/her sitting posture, such that the sensing device encourages, leads and urges the occupant to have optimum sitting posture. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0035]FIGS. 1 and 2 illustrate good sitting postures and faulty sitting postures of a person sitting in a chair, and a seat, respectively.  
     [0036]FIGS. 3 and 4 are side elevation views of a person sitting in the seat of FIG. 2, wherein the most pertinent portions of the skeletal structure of the person are depicted in phantom.  
     [0037]FIGS. 5, 6, and  7  are perspective views of chairs and a seat to which the sensing device of the present invention are provided.  
     [0038]FIG. 8 is a sectional view taken along the line M-M in FIG. 7.  
     [0039]FIGS. 9 through 15 are perspective views of chairs, seats and subsidiaries for sitting means to which the sensing devices of the present invention are applied.  
     [0040]FIGS. 16 through 19 are block diagrams of sensing devices in accordance with the present invention.  
     [0041]FIG. 20 is a flowchart showing a main routine for operational procedures of sensing device of the present invention. Like numerals refer to like parts throughout the several views of the drawings. 
    
    
     BEST MODES FOR CARRYING OUT THE INVENTION  
     [0042] In the present invention, one or a plurality of sensing means are provided to the parts of the seat member and/or the back member of a sitting means to which the body of an occupant is contacting when an occupant sits in the sitting means in right sitting posture.  
     [0043] For convenience, the sensing means to be contacted by several parts of the body of an occupant are indicated as seat sensor ( 23 ), hip sensor ( 33 ), spine sensor ( 37 ), blade sensors ( 35 ) and ( 35 ′), head sensor ( 38 ) and so on, each of which will be described hereinafter.  
     [0044] Referring to FIGS. 5 and 16, there are shown a sensing device and a chair ( 57 ) having seat member ( 21 ) and back member ( 31 ) combined with said sensing device in accordance with the present invention.  
     [0045] The “sitting means” is of the type which has a substantially horizontal seat member which supports the thigh bones and pelvis of an occupant and a substantially vertical back member which is vertically positioned above the seat member and is adapted to provide support to the back of the occupant.  
     [0046] The sensing device basically comprises the seat sensor ( 23 ) and the hip sensor ( 33 ), a responding means (RM) ( 95 ), a switch part (SP) ( 93 ), a power supply (PS) ( 97 ) and a microcomputer ( 91 ).  
     [0047] The seat sensor ( 23 ) is provided to the part of the seat member ( 21 ) to which thighs and pelvis of an occupant contact and the hip sensor ( 33 ) is provided to the lower part of the back member ( 31 ) to which the hip of the occupant contacts.  
     [0048] The unit or assembly comprised of microcomputer ( 91 ), switch part ( 93 ), responding means ( 95 ) and power supply ( 97 ) is indicated as a “control unit ( 90 )”.  
     [0049] The operating mode of the sensing device of the present embodiment comprised of the seat sensor ( 23 ), hip sensor ( 33 ) and the control unit ( 90 ) is indicated herein as “hip-sensing mode”.  
     [0050] The sensor may be any sensor (i.e. electrical, mechanical, piezoelectric, thermal, infrared LED, and so on) which generates electrical signal when a physical body contacts thereto, an external force is applied thereto or the sensor is activated upon detecting the presence of a physical body, which is well known to those skilled in the art.  
     [0051] When an occupant sits on the sitting means and contacts or activates the sensors provided to the sitting means (e.g. sensors ( 23 ), ( 33 )), each sensor generates an electrical signal and sends it to the microcomputer ( 91 ).  
     [0052] For convenience, the term “contact” is used to representatively denote the expression “contact and/or activate” throughout the specification.  
     [0053] The microcomputer ( 91 ) stores in memory data for the sensor(s) provided to the sitting means, data for the signal generated by each sensor, and data for the number(s) of said sensor(s), in a predetermined program, and the microcomputer ( 91 ) is further programmed to discriminate which signal is generated by which sensor, to compare the number of the signal(s) sent by the sensor(s) with the number of the sensor(s) preset in said predetermined program, and to order the responding means either to respond or not, according to said predetermined program.  
     [0054] Thus, the microcomputer ( 91 ) proceeds operations according to the predetermined program as follows;  
     [0055] First, the microcomputer ( 91 ) examines the presence of signal(s) sent thereto by the sensor(s). If no signal is detected, the microcomputer ( 91 ) let the responding means ( 95 ) remain in non-responding state. If there exist a signal(s) sent thereto, the microcomputer ( 91 ) discriminates which signal is generated by which sensor and compares the number of the signal(s) with the preset number of the sensor(s). Then, the microcomputer ( 91 ) orders the responding means ( 95 ) either to respond or not, according to the predetermined program.  
     [0056] In detail, when an occupant sitting on the sitting means contacts the sensor(s), and thereby the number of the signal(s) sent to the microcomputer ( 91 ) coincides with the preset number of the sensor(s), the microcomputer ( 91 ) let the responding means ( 95 ) remain in non-responding state. And, when an occupant sitting on the sitting means does not contact at least any one sensor, and thereby the number of the signal(s) sent to the microcomputer ( 91 ) does not coincide with the preset number of the sensor(s), the microcomputer ( 91 ) orders the responding means ( 95 ) to produce responding signal.  
     [0057] When the responding means ( 95 ) produces responding signal, it is arranged such that the response is stopped when the occupant, upon recognizing the responding signal, corrects his/her sitting posture and contacts all the sensor(s) the number of which is preset in the microcomputer ( 91 ).  
     [0058] The responding means (RM) ( 95 ) includes devices for producing an auditory signal such as an electronic tone generator or a speaker, devices for producing a visible signal such as a light bulb or a light-emitting diode (LED) and/or devices for producing a vibratory signal such as a mechanical vibrator unit, known in the art.  
     [0059] The responding means ( 95 ) produces an auditory signal (sound), a visible signal (light) and/or a vibratory signal (vibration) in accordance with the order of said microcomputer.  
     [0060] The numeral ( 93 ) denotes switch part (SP). The switch part ( 93 ) is provided with several switches the kinds and functions of which will be explained later. The numeral ( 97 ) denotes power supply (PS). The power supply ( 97 ) may be battery supplied, for example, within the control unit ( 90 ) or A/C power supplied via a plug.  
     [0061] The sensors (e.g. ( 23 ) and ( 33 )), microcomputer ( 91 ), responding means ( 95 ), switch part ( 93 ), and power supply ( 97 ) are electrically interconnected to one another by electric wires and/or circuits. The control unit ( 90 ) can be affixed to or positioned within the sitting means. In FIGS. 5, 6 and  7  the control unit ( 90 ) is affixed to the bottom side of the seat member ( 21 ) and in FIGS. 9 and 12 the control unit ( 90 ) is positioned at the lateral wall of a seat cushion (seat member ( 21 )).  
     [0062] In FIGS. 5, 9, etc., the seat sensor ( 23 ) is provided to the front part of the seat member ( 21 ) to which the thigh bones contact. Further, the seat sensor ( 23 ) may be provided, as shown in FIG. 7, to the rear part of the seat member ( 21 ) to which the ischial tuberosities contact.  
     [0063] When the seat sensor ( 23 ) is provided to the rear part of the seat member ( 21 ), proximate the horizontal line at the center of the seat member ( 21 ) such as the line (L) shown in FIG. 7, it is directly contacted by the ischial tuberosities of the occupant, and thereby the ischial tuberosities of the occupant can be firmly supported on the seat member ( 21 ). As the armrest is considered as a part of the seat member, the seat sensor ( 23 ) may be provided to the armrest.  
     [0064] Further, as shown in FIG. 12, two seat sensors ( 23 ) and ( 23 ′) may be provided to the front part of the seat member ( 21 ) to be contacted by two thigh bones, respectively.  
     [0065] With this arrangement, when the occupant in the seat member ( 21 ) crosses his/her legs, as one thigh is not contacting any one of the seat sensors ( 23 ), ( 23 ′), the sensing device of the present embodiment notifies the occupant to let the two thighs be paralleled and touch the sensors ( 23 ), ( 23 ′).  
     [0066] In the same way, when the seat sensor ( 23 ) is provided to the rear part of the seat member ( 21 ), proximate the horizontal line (L) thereof as shown in FIG. 7, either only one seat sensor ( 23 ) is provided thereto or two seat sensors ( 23 ) and ( 23 ′) are provided thereto to be contacted by the two ischial tuberosities of the occupant (not shown).  
     [0067] When the occupant sitting on the seat member ( 21 ) which has two seat sensors ( 23 ) and ( 23 ′) provided to the rear part of the seat member ( 21 ), proximate the horizontal line (L) thereof such as shown in FIG. 7 tilts his/her upper body part sideways, with any one of the right and left ischial tuberosities not contacting any one of the sensors ( 23 ), ( 23 ′), the sensing device of the present embodiment notifies the occupant to correct his/her sitting posture by letting the two ischial tuberosities of the occupant evenly contact the two seat sensors ( 23 ) and ( 23 ′).  
     [0068] The hip sensor ( 33 ) is provided to the lower part of the back member ( 31 ) on which the hip contacts when an occupant let the hip be posteriorly and inferiorly positioned to contact the lower part of the back member ( 31 ) as shown in FIGS. 5 through 13.  
     [0069] In some chairs, a lumbar-supporting element is separately manufactured and provided to the front of the lower part of the back member ( 31 ) to support the lumbar region. In FIG. 9, a pillow-type lumbar-supporting element ( 77 ) is positioned in the front of the lower part of the back member ( 31 ) of the chair ( 63 ). Further, the back members of some seats are provided with a mechanically inflatable device or fluid-inflatable device (not shown) which is positioned within or to the front of lower part of the back member and can be moved forward and backward to provide support and spinal movement to the lumbar region of an occupant.  
     [0070] In these cases, the hip sensor ( 33 ) is provided to the part of the lumbar-supporting element, the mechanically inflatable device or the fluid-inflatable device to which the hip of an occupant contact.  
     [0071] It is preferable that the hip sensor ( 33 ) is provided to the back member ( 31 ) to be positioned, within the range of 5 cm-30 cm, from the surface of the rear part of the seat member ( 21 ).  
     [0072] In some chairs similar to the chair ( 59 ) in FIG. 6, the back member is mounted on the upper part of an “L” shaped support member ( 25 ) that is connected to the body of the seat member ( 21 ). When the back member ( 31 ) is mounted on the upper part of an “L” shaped support member ( 25 ) such that there exists wide space between the seat member ( 21 ) and the lower part of the back member ( 31 ), the hip sensor ( 33 ) may be provided to the support member ( 25 ), within the space between the seat member ( 21 ) and the lower part of the back member ( 31 ) as shown in FIG. 6, in order to be contacted by the seat occupant&#39;s hip.  
     [0073] The back member ( 31 ) of the chair ( 61 ) in FIG. 7 is mounted on the laterally spaced apart support legs ( 22 ) and rails ( 34 ) bridging between the support legs ( 22 ). These types of chairs have some space or an opening ( 32 ) in the lower portion of the back member, directly above the edge of the seat member, so that no support is provided for the seat occupant&#39;s hip.  
     [0074] When the lower portion of the back member ( 31 ) has an opening ( 32 ) and no support is provided to the hip as shown in FIG. 7, an “L” shaped support member ( 25 ) may be separately prepared and affixed to the body of the seat member ( 21 ) to accommodate the hip sensor ( 33 ) attached thereto as shown in FIGS. 7 and 8 (The FIG. 8 is the sectional view taken along the line M-M in FIG. 7).  
     [0075] Further, in case of some shell-typed chairs in which the seat member ( 21 ) and back member ( 31 ) are formed in one piece such that the lower part of the back member ( 31 ) connects with the rear edge of the seat member ( 21 ), the lower part of the back member to which the round hip contacts is concave backward to comfortably receive the round hip. In this case, the hip sensor ( 33 ) may be provided to the concave part of the back member for the round hip area to naturally contact thereto.  
     [0076] Further, it is preferable that the hip sensor ( 33 ) is positioned a little behind the substantially vertical, plane surface of the back member ( 31 ) in order to easily contact the round hip portion of the occupant. For example, as shown in FIG. 8, the hip sensor ( 33 ) is so provided to the top of the “L” shaped support member ( 25 ) as to be positioned, with the depth “g”, behind the vertical, plane surface ( 36 ) of the back member ( 31 )  
     [0077] The operating procedure of the hip-sensing mode is as follows.  
     [0078] When an occupant sits on the chair and touches the seat sensor ( 23 ) and hip sensor ( 33 ), each sensor generates and sends a signal to the microcomputer ( 91 ), respectively.  
     [0079] When an occupant sits in right sitting posture, in a similar fashion shown in the right of FIGS. 1 and 2, with the thigh bones contacting the seat sensor ( 23 ) and the hip contacting the hip sensor ( 33 ), the two signals generated by the sensors ( 23 ) and ( 33 ) are sent to the microcomputer ( 91 ). Upon receiving all the signals of the sensors ( 23 ) and ( 33 ), the microcomputer ( 91 ) let the responding means ( 95 ) remain in non-responding state.  
     [0080] When an occupant sits in faulty sitting posture in a similar manner shown in the left of FIGS. 1 and 2, he/she merely contacts any one of the sensors ( 23 ) and ( 33 ). Accordingly, the untouched sensor does not generate/send a signal to the microcomputer ( 91 ).  
     [0081] Upon receiving the signal the number of which is less than the preset number of the sensors, the microcomputer ( 91 ) orders the responding means ( 95 ) to produce responding signal (such as sound, light and/or vibration). Thus, when the responding means produces responding signal, the occupant becomes aware that he/she does not contact the sensor ( 23 ) and/or the sensor ( 33 ).  
     [0082] Immediately after the response, the occupant tries to have right sitting posture with the thigh bones contacting the seat sensor ( 23 ) and the hip contacting the hip sensor ( 33 ) by letting the hip be posteriorly and inferiorly positioned and contact the lower part of the back member ( 31 ). Thus, as the signals of all the sensors ( 23 ) and ( 33 ) are sent to the microcomputer ( 91 ), the microcomputer ( 91 ) orders the responding means ( 95 ) to stop producing responding signal.  
     [0083] Accordingly, a person sitting in the sitting means combined with the sensing device of the present embodiment can have optimum sitting posture with the thigh bones being stably positioned on the seat member ( 21 ) and the hip being posteriorly and inferiorly positioned and contacting the lower part of the back member ( 31 ).  
     [0084] In the light of physiological aspects, a person in a sitting means having the sensing device of the present embodiment can have optimum sitting posture with the pelvic girdle including ilia, sacrum, and coccyx being posteriorly and inferiorly positioned and contacting the lower part of the back member ( 31 ), the ischial tuberosities being firmly supported on the seat member ( 21 ), and the spinal column being physiologic, erect and static. Namely, with the pelvis being supported in physiologic position as depicted in FIG. 4, the lumbar and pelvic bones are firmly held in position, thereby minimizing the amount of movements of the muscles, ligaments and tendons associated therewith. Such posture is effortless and therefore non-fatiguing. Accordingly, the occupant can concentrate on his/her work or study with comfort.  
     [0085] This feature is one of the advantages of the invention that would clearly be of great importance to persons in sedentary occupations, who spend long hours or perhaps the entire workday in a chair.  
     [0086] A further embodiment of the present invention relates to a sensing device having sensors for contacting the thigh, pelvic and spinal bones of an occupant. FIGS. 7 and 17 illustrate a sensing device of the present embodiment combined with a chair ( 61 ).  
     [0087] In this embodiment, in addition to the parts comprising above said hip-sensing mode, a second back sensor is provided to the middle part of the back member ( 31 ), along the vertical line (V) at the center of the back member ( 31 ), to which the thoracic vertebrae contact when the occupant straightens his/her spinal column. Hereinafter, the second back sensor provided to the back member ( 31 ) is indicated as the “spine sensor (SPS) ( 37 )”. The operating mode of the sensing device of the present embodiment comprised of the seat sensor ( 23 ), hip sensor ( 33 ), spine sensor ( 37 ) and the control unit ( 90 ) is indicated herein as “spine-sensing mode”.  
     [0088] It is preferable that the spine sensor ( 37 ) is provided to the back member ( 31 ) to be positioned, within the range of 30 cm-70 cm, from the surface of the rear part of the seat member ( 21 ).  
     [0089] The operating procedure of the spine-sensing mode is as follows.  
     [0090] When an occupant sits on the chair and touches the seat sensor ( 23 ), hip sensor ( 33 ) and the spine sensor ( 37 ), the three sensors generate and send signals to the microcomputer ( 91 ), respectively.  
     [0091] When an occupant sits in right sitting posture with the thighs contacting the seat sensor ( 23 ), the hip contacting the hip sensor ( 33 ), and the thoracic vertebrae contacting the spine sensor ( 37 ) at the middle part of the back member ( 31 ) by straightening his/her spinal column, the three signals of the sensors ( 23 ), ( 33 ) and ( 37 ) are sent to the microcomputer ( 91 ), respectively. Upon receiving the signals of the sensors ( 23 ), ( 33 ) and ( 37 ), the microcomputer ( 91 ) let the responding means remain in non-responding state.  
     [0092] When an occupant does not contact at least any one of the sensors ( 23 ), ( 33 ) and ( 37 ), the untouched sensor does not generate/send a signal to the microcomputer ( 91 ). Upon receiving the signals the number of which is less than the preset number of the sensors, the microcomputer ( 91 ) orders the responding means to respond.  
     [0093] Thus, when the responding means responds, the occupant becomes aware that he/she does not contact the sensors ( 23 ), ( 33 ) and/or ( 37 ). Immediately after the response, the occupant tries to have optimum sitting posture with the thigh bones contacting the seat sensor ( 23 ), the hip contacting the hip sensor ( 33 ), and the thoracic vertebrae contacting the spine sensor ( 37 ) by straightening his/her spinal column. Thus, as the signals of all the sensors ( 23 ), ( 33 ) and ( 37 ) are sent to the microcomputer ( 91 ), the microcomputer ( 91 ) orders the responding means ( 95 ) to stop producing responding signal.  
     [0094] Accordingly, a person sitting in the sitting means combined with the sensing device of the present embodiment can have optimum sitting posture with the thigh bones being stably positioned on the seat member ( 21 ), the hip being posteriorly and inferiorly positioned and contacting the lower part of the back member ( 31 ), and the thoracic vertebrae being straightened and contacting the middle part of the back member ( 31 ). In the light of medical aspects, the hip and spine sensors ( 33 ), ( 37 ) encourage the proper chest expansion and spinal straightness so that the spine is physiologic, erect and static, and movements and stresses are minimized in the lumbar and thoracic spine.  
     [0095] Still a further embodiment of the present invention relates to a sensing device having sensors for contacting the thigh bones, pelvic bones, and shoulder blades and/or ribs of an occupant. As an example, FIGS. 10 and 19 show a sensing device of the present embodiment combined with a chair ( 65 ).  
     [0096] In this embodiment, in addition to the parts comprising above said hip-sensing mode, a pair of sensors (the third back sensor) is provided to the back member ( 31 ). Hereinafter, the third back sensor provided to the back member ( 31 ) are indicated as the “blade sensors (BLS) ( 35 ) and ( 35 ′)”.  
     [0097] The blade sensors ( 35 ) and ( 35 ′) are provided, as shown in FIG. 10, to the upper part of the back member ( 31 ) to which the shoulder blades and/or ribs are contacting when the occupant straightens his/her spinal column and expands the chest. The two blade sensors ( 35 ), ( 35 ′) are provided to be horizontally spaced apart and symmetrical to each other along the vertical line (V) at the middle of said back member. It is preferable that the blade sensors ( 35 ) and ( 35 ′) are provided to said back member to be positioned, within the range of 30 cm-90 cm, from the surface of the rear part of the seat member ( 21 ).  
     [0098] The back member ( 31 ) may be formed to have a pair of slightly raised portions on the surface thereof in order to fit the natural physical curvature of the ribs of an occupant and the blade sensors ( 35 ) and ( 35 ′) may be provided to said raised portions. In FIG. 13, the numerals ( 39 ) and ( 39 ′) denote the vertically extending raised portions formed on the surface of the back member ( 31 ) of the chair ( 69 ). The raised portions ( 39 ) and ( 39 ′) are formed to be symmetrical to each other along either side of the vertical centerline (V) of the back member ( 31 ), and the blade sensors ( 35 ) and ( 35 ′) are provided to the raised portions ( 39 ) and ( 39 ′), respectively.  
     [0099] In some sitting means, especially in some automobile seats similar to the seat ( 68 ) shown in FIG. 12, there has been available a pair of side support members at the respective lateral sides of the back member of the seat in order to support both sides (ribs) of an occupant on the seat. In a sense, these side support members may be considered as a similar kind of above said raised portion ( 39 ) and ( 39 ′).  
     [0100] The blade sensors ( 35 ) and ( 35 ′) may also be provided to these side support members to contact the ribs. In FIG. 12, the numerals ( 40 ) and ( 40 ′) denote these side support members and the blade sensors ( 35 ) and ( 35 ′) are provided to the side support members ( 40 ) and ( 40 ′), respectively.  
     [0101] The operating mode of the sensing device of the present embodiment comprised of the seat sensor ( 23 ), hip sensor ( 33 ), blade sensors ( 35 ), ( 35 ′) and the control unit ( 90 ) is indicated herein as “blade-sensing mode”. The operating procedure of the blade-sensing mode is similar to those described in connection with the hip-sensing mode and the spine-sensing mode. Namely, when an occupant on the sitting means contacts all the sensors ( 23 ), ( 33 ), ( 35 ) and ( 35 ′) the microcomputer ( 91 ) let the responding means ( 95 ) remain in non-responding state.  
     [0102] When the occupant does not contact at least any one of the sensors ( 23 ), ( 33 ), ( 35 ), and ( 35 ′) the microcomputer ( 91 ) orders the responding means to respond, and the microcomputer ( 91 ) orders the responding means ( 95 ) to stop producing responding signal when the occupant corrects his/her sitting posture and again contacts all the sensors ( 23 ), ( 33 ), ( 35 ) and ( 35 ′).  
     [0103] Accordingly, a person sitting in the sitting means combined with the sensing device of the present embodiment can have optimum sitting posture with the thigh bones being stably positioned on the seat member ( 21 ) and contacting the seat sensor ( 23 ), the hip being posteriorly and inferiorly positioned and contacting the hip sensor ( 33 ) at the lower part of the back member ( 31 ), and the two shoulder blades and/or ribs contacting the blade sensors ( 35 ) and ( 35 ′) at the upper part of the back member ( 31 ) by straightening his/her spinal column and expanding the chest.  
     [0104] In the light of medical aspects, these two horizontally spaced blade sensors ( 35 ) and ( 35 ′) help and urge the occupant to expand the chest, reduces excessive kyphosis, encourages deeper breathing, and tends to align the upper spine with reduced curvature and minimal muscular and skeletal stress in the thoracic, cervical and lumbar spine region.  
     [0105] Still a further embodiment of the present invention relates to a sensing device having sensors for contacting the thigh, pelvic and cranial bones of an occupant. As an example, FIGS. 9 and 18 illustrate a sensing device of the present embodiment combined with an office chair ( 63 ) (or a passenger seat) having a headrest. Generally, a headrest is provided to a sitting means as a component of the back member of the sitting means.  
     [0106] Normally, a passenger rests his/her head on the middle part of the headrest with the neck being straightened. However, as a common sight, a sleeping passenger unconsciously tilts the head sideways and leans against the body of other person who sits next, which not only gives others an unpleasant feeling but also is a shameful thing for the sleeping passenger himself/herself.  
     [0107] Further, what is worse, the excessive tilting of the head sideways inevitably requires excessive movements of the muscles, ligaments and tendons associated with the cervical bones. In order to prevent the unconscious tilting of the head and to improve the resting posture of the head, in this embodiment, in addition to the parts comprising above said hip-sensing mode, a fourth back sensor is provided to the headrest ( 30 ) of the back member ( 31 ). The fourth sensor is provided to the middle part of the headrest ( 30 ) of the back member ( 31 ), to which the cranial bone contacts when the occupant rests his/her head thereon, as shown in FIG. 9. Hereinafter, the fourth sensor provided to the headrest ( 30 ) is indicated as the “head sensor (HRS) ( 38 )”.  
     [0108] The operating mode of the sensing device of the present embodiment comprised of the seat sensor ( 23 ), hip sensor ( 33 ), head sensor ( 38 ) and the control unit ( 90 ) is indicated herein as “head-sensing mode”.  
     [0109] The operating procedure of the head-sensing mode is similar to those described in connection with the hip-sensing mode and the spine-sensing mode. Namely, when an occupant on the sitting means contacts all the sensors ( 23 ), ( 33 ) and ( 38 ), the microcomputer ( 91 ) let the responding means ( 95 ) remain in non-responding state,  
     [0110] When the occupant does not contact at least any one of the sensors ( 23 ), ( 33 ) and ( 38 ) the microcomputer ( 91 ) orders the responding means to respond, and the microcomputer ( 91 ) orders the responding means ( 95 ) to stop producing responding signal when the occupant corrects his/her sitting posture and again contacts all the sensors ( 23 ), ( 33 ) and ( 38 ).  
     [0111] Accordingly, a person sitting in the sitting means combined with the sensing device of the present embodiment can have optimum sitting posture with the thigh bones being stably positioned on the seat member ( 21 ) and contacting the seat sensor ( 23 ), the hip being posteriorly and inferiorly positioned and contacting the hip sensor ( 33 ) at the lower part of the back member ( 31 ), and the head contacting the head sensor ( 38 ) and resting on the middle part of the headrest ( 30 ).  
     [0112] In the light of medical aspects, the head sensor ( 38 ) will tend to align the skeletal and cervical bones so that the head is balanced easily over it with reduced curvature and minimal muscular and skeletal stress in the skeletal, cervical and thoracic spine region.  
     [0113] Some occupants who sit down on and stand up from the seat member ( 21 ) frequently may want the sitting means to have no sensor(s) provided thereto in order to freely use the sitting means. However, when they work or study on said sitting means during relatively long time period, they may want the sitting means to have sensor(s) in order to sit in right sitting posture with the hip contacting the lower part of the back member ( 31 ). For these occupants, the sensor(s) may be provided only to the back member ( 31 ).  
     [0114] First, only the hip sensor ( 33 ) may be provided to the lower part of the back member ( 31 ) such that the occupant can freely use the sitting means while he/she works or studies during certain time period with the hip contacting the hip sensor ( 33 ). The operating mode of the sensing device of the present embodiment comprised of the hip sensor ( 33 ) and the control unit ( 90 ) is indicated herein as a “basic sensing mode”. The operating procedure of the basic sensing mode will be described later.  
     [0115] Second, in addition to the hip sensor ( 33 ), a further sensor(s) may be provided to the back member ( 31 ). Namely, the hip sensor ( 33 ) is basically provided to the back member ( 31 ) and at least one sensor among the sensors for the back member ( 31 ) such as spine sensor ( 37 ), the blade sensors ( 35 ), ( 35 ′) and/or the head sensor ( 38 ) may be provided to the back member ( 31 ). The operating mode of the sensing device of the present embodiment comprised of a plurality of sensors provided to the back member ( 31 ) and the control unit ( 90 ) is indicated herein as a “back-sensing mode”.  
     [0116] An example of the operating procedure of the back-sensing mode is as follows.  
     [0117] When a sitting means has a back member ( 31 ) having a hip sensor ( 33 ) and a spine sensor ( 37 ) provided thereto and a seat member ( 21 ) having no sensor provided thereto, first, an occupant can freely use said sitting means without contacting the back member ( 31 ).  
     [0118] If the occupant desires to work or study during certain time period, he/she can sit in right sitting posture with the hip contacting the hip sensor ( 33 ) and the spinal column contacting the spine sensor ( 37 ). When the occupant contacts said sensors ( 33 ) and ( 37 ), the two sensors generate/send signals to the microcomputer ( 91 ), respectively. Upon receiving the signals of the sensors ( 33 ) and ( 37 ), the microcomputer ( 91 ) let the responding means ( 95 ) remain in non-responding state.  
     [0119] When an occupant does not contact any one of the sensors ( 33 ) and ( 37 ), the untouched sensor does not generate/send a signal to the microcomputer ( 91 ). Upon receiving the signal the number of which is less than the preset number of the sensors, the microcomputer ( 91 ) orders the responding means ( 95 ) to produce responding signal.  
     [0120] Thus, when the responding means produces responding signal, the occupant becomes aware that he/she does not contact the sensors ( 33 ) and ( 37 ).  
     [0121] Immediately after the response, the occupant tries to have optimum sitting posture with the hip contacting hip sensor ( 33 ) and the spinal column contacting said spine sensor.  
     [0122] Thus, as the signals of all the sensors ( 33 ) and ( 37 ) are sent to the microcomputer ( 91 ), the microcomputer orders said responding means to stop producing responding signal.  
     [0123] If desired, all the sensors for the sensing modes heretofore described (i.e., the seat sensor ( 23 ), hip sensor ( 33 ), spine sensor ( 37 ), blade sensors ( 35 ) and ( 35 ′), and the head sensor ( 38 )) may altogether be provided to one sitting means.  
     [0124] Further, the sensor(s) may be provided to certain place(s) of the seat member and/or back member for certain purposes. For example, a sensor may be provided to the right or left upper part of the back member for the patient having scoliosis.  
     [0125] In some cases, a sitting means has a plurality of back members mounted on the upper part of the “L” shaped support member(s) ( 25 ) that is connected to the body of the seat member ( 21 ) in order to support the back of an occupant. The various sensing modes of the present invention heretofore explained can also be embodied in these types of sitting means by providing corresponding sensors to these types of sitting means.  
     [0126] For example, the chair ( 67 ) in FIG. 11 has a seat member ( 21 ) having seat sensor ( 23 ) and two small back members ( 31 ) and ( 31 )′ that have two hip sensors ( 33 ), ( 33 )′ and two blade sensors ( 35 ), ( 35 ′) provided thereto. The two blade sensors ( 35 ), ( 35 ′) may be provided to the lower, outer end parts (or lower, middle parts) of the small back members ( 31 ) and ( 31 )′ in order to contact the lower ribs of the body. If the spine sensor ( 37 ) is provided to this type of sitting means, the spine sensor ( 37 ) may be provided to the “L” shaped support member ( 25 ) in the space between the two small back members ( 31 ) and ( 31 ′). As a further example, two spine sensors ( 37 ), ( 37 ′) (not shown) may be provided to the inner extremities ( 45 ), ( 45 ′) of the two small back members ( 31 ) and ( 31 ′), respectively.  
     [0127] Still a further embodiment of the present invention relates to the sensing devices of the present invention combined with covering members for sitting means such as covers, mat-type support members, and the like. Generally, a cover is later placed over a sitting means in order to protect and retain the surface and structure of the sitting means, and a mat-type support member is provided to a sitting means for ensuring comfort, ventilation and/or treatment of lumbar pains of an occupant in the sitting means which is covered with the mat-type support member.  
     [0128] The covers are generally made of natural or synthetic materials such as linen, fabric, leather, fur or corresponding plastics. FIG. 14 illustrates a cover ( 70 ) for sitting means made of cloths. The mat-type support members are either mesh arrangements of wires, strings, cords, bead-strings, bars, or the like within a rectangular peripheral frame, or disk-like elements of supple or rigid materials.  
     [0129]FIG. 15 illustrates a mat-type support member ( 75 ) comprised of a plurality of bar-shaped element ( 76 ) of slightly rigid material such as plastics and the like. These bar/shaped elements ( 76 ) are connected to each other by means of chains. Known fastening or attaching means such as strings, Velcro.RTM. Fastener, snaps, buttons, bolts and nuts, and so on may be employed to fasten the cover or mat-type support member to the sitting means. In FIGS. 14 and 15, numerals ( 74 ) denote strings to fasten the cover ( 70 ) and the mat-type support member ( 75 ) to a sitting means. Herein, the term “covering member” is used to altogether indicate the “cover” and the “mat-type support member” 
     [0130] The covering member has a seat covering element ( 71 ) which supports the thighs and pelvis of an occupant and a back covering element ( 73 ) which is vertically positioned above the seat covering element ( 71 ) and supports the back of the occupant, when said covering member is placed over said sitting means. For some chairs having headrests, the covering member may have a headrest part as a part of the back covering element ( 73 ).  
     [0131] Above said various embodiments of the sensing device of the present invention may also be embodied in these covering members. The sensors in the above embodiments are provided to the places of the covering members where the thighs, hips, spine, shoulder blades and/or ribs, and/or the head of the occupant contact when said covering members are placed on the sitting means. For examples, in FIGS. 14 and 15, above said spine-sensing mode is embodied in the cover ( 70 ) and mat-type support member ( 75 ), respectively, i.e., seat sensor ( 23 ), hip sensor ( 33 ) and spine sensor ( 37 ) are provided to the seat covering elements ( 71 ) and back covering elements ( 73 ) of the cover ( 70 ) and mat-type support member ( 75 ), respectively. The control unit ( 90 ) is connected to these sensors through electric wires.  
     [0132] A sensor-selecting switch may optionally be provided to the switch part ( 93 ) for the occupant to select the sensor(s) that he/she wants to operate among the sensors provided to the sitting means.  
     [0133] When a sensor-selecting switch is provided to the switch part ( 93 ), the microcomputer ( 91 ) is programmed to proceed operations for plural sensing modes corresponding to the groups of selected sensor(s).  
     [0134] Namely, the microcomputer ( 91 ) stores in memory data for some of and/or all the sensor(s) provided to the sitting means, data for the signal generated by each sensor, and data for the number(s) of said some of and/or all the sensor(s), in a predetermined program, and the microcomputer ( 91 ) is also programmed to discriminate which signal is generated by which sensor and to compare the number of the signal(s) sent by said some of and/or all the sensor(s) with the number of said some of and/or all the sensor(s) preset in said predetermined program, and to order the responding means either to respond or not, according to said predetermined program. Thus, when a plurality of sensors and a sensor-selecting switch are provided to the sitting means, the microcomputer ( 91 ) stores in memory and processes data for the group(s) of sensor(s) corresponding to above said several sensing mode(s).  
     [0135] The group of sensor(s) selected by the sensor-selecting switch includes at least the hip sensor ( 33 ), and may be classified as follows;  
     [0136] 1. hip sensor ( 33 )  
     [0137] 2. seat sensor ( 23 ) and hip sensor ( 33 )  
     [0138] 3. seat sensor ( 23 ), hip sensor ( 33 ) and spine sensor ( 37 )  
     [0139] 4. seat sensor ( 23 ), hip sensor ( 33 ) and blade sensors ( 35 ), ( 35 ′)  
     [0140] 5. seat sensor ( 23 ), hip sensor ( 33 ) and head sensor ( 38 )  
     [0141] 6. seat sensor ( 23 ), hip sensor ( 33 ), blade sensors ( 35 ), ( 35 ′) and head sensor ( 38 )  
     [0142] 7. hip sensor ( 33 ) and spine sensor ( 37 )  
     [0143] 8. hip sensor ( 33 ) and blade sensors ( 35 ), ( 35 ′)  
     [0144] 9. hip sensor ( 33 ), blade sensors ( 35 ), ( 35 ′), and head sensor ( 38 ), and so on.  
     [0145] For example, when a sensor-selecting switch is provided to the switch part ( 93 ) of the chair ( 61 )(in FIG. 7) which is provided with the seat sensor ( 23 ), hip sensor ( 33 ) and the spine sensor ( 37 ), the occupant can choose the sensor(s) for the sensing mode he/she wants.  
     [0146] First, when the sensor-selecting switch is changed to select only the hip sensor ( 33 ), the microcomputer ( 91 ) processes the procedures of above said basic sensing mode comprised of the hip sensor ( 33 ) and the control unit ( 90 ).  
     [0147] Second, when the sensor-selecting switch is changed to select the seat sensor ( 23 ) and the hip sensor ( 33 ), the microcomputer ( 91 ) processes the procedures of above said hip-sensing mode comprised of the sensors ( 23 ), ( 33 ) and the control unit ( 90 ).  
     [0148] Third, when the sensor-selecting switch is changed to select the seat sensor ( 23 ), hip sensor ( 33 ) and the spine sensor ( 37 ), the microcomputer ( 91 ) processes the procedures of above said spine-sensing mode comprised of the sensors ( 23 ), ( 33 ), ( 37 ) and the control unit ( 90 ).  
     [0149] Fourth, when the sensor-selecting switch is changed to select the hip sensor ( 33 ) and the spine sensor ( 37 ), the microcomputer ( 91 ) processes the procedures of above said back-sensing mode comprised of the sensors ( 33 ), ( 37 ) and the control unit ( 90 ).  
     [0150] Thus, when a plurality of sensors are provided to the sitting means, the sensor-selecting switch enables the occupant to freely convert the sensing mode through the selection of the corresponding sensors with the sensor-selecting switch.  
     [0151] The same kind of sensors may be provided consecutively or in a spaced apart manner for the occupant to select the sensor that is positioned at the place where he/she wants.  
     [0152] In FIG. 13, the same seat sensors ( 23 A) and ( 23 B) are secured to the front part and rear part of the seat member ( 21 ), respectively, and the same hip sensors ( 33 A) and ( 33 B) are secured, side-by-side, to the back member ( 31 ).  
     [0153] When the occupant wants the hip sensor ( 33 ) to be positioned slightly upward at the lower part of the back member ( 31 ), he/she can select the hip sensor ( 33 B), and, in turn, when he/she wants it to be positioned at the extremity of the lower part of the back member ( 31 ), he/she can select the hip sensor ( 33 A). In the same way, the occupant can alternately select the seat sensor ( 23 A) and ( 23 B). With these arrangements, the occupant can select the sensors he/she wants among the same sensors with the sensor-selecting switch.  
     [0154] The sensors of the present invention may be secured beneath the outer covering of cloths, leathers, vinyl or any other synthetic materials of said seat member and back member.  
     [0155] Further, the sensors may be attached on the surfaces of the seat member and back member.  
     [0156] The sensors may be so provided in a slightly convex fashion on the surfaces of the seat member ( 21 ) and back member ( 31 ) that the body of the occupant may easily contact the sensors. For example, as shown in FIG. 8, the sensor ( 37 ) in FIG. 7 is provided in a slightly convex fashion on the surface ( 36 ) of the back member ( 31 ).  
     [0157] In case of a shell-typed panel chair, a hole(s) corresponding to the size and shape of the sensor(s) may be formed to receive the sensor(s).  
     [0158] The switch part ( 93 ) is provided with several kinds of switches. The first switch may be a power supply switch for selecting “on/off mode” of the power supply ( 97 ). The second switch may be a responding-device-selecting switch that is capable of switching over among above said responding devices for producing an auditory-signal, a visible signal and/or a vibratory signal. The third switch may be a sensor-selecting switch that enables the occupant to choose the sensor(s) he/she wants.  
     [0159] The fourth switch may be a time adjusting switch that adjusts the standard hold time to defer the response of the responding means ( 95 ).  
     [0160] The sensing device of the present invention provides a further advantage that leads the occupant to maintain the neutral spine position. It has been recommended to let the weight of the upper body part of the occupant be evenly dispersed to the back member of a sitting means in order to maintain the neutral spine position. Generally, the backward pressing force of the upper part of the back of the occupant applied to the upper part of the back member is greater than that of the hip contacting the lower part of said back member when the occupant leans the upper body part backwardly.  
     [0161] Thus, the stronger the backward pressing force of the upper part of the back of an occupant is, the more the lumbar vertebral arch is forwardly convex, causing too excessive lordosis which is well known to be the most common cause of low back pain and sciatica. Thus, it sometimes is required to let the backward pressing force of some part of the back of an occupant be not too greater than that of the other part of the back of the occupant in order to maintain the neutral spine position.  
     [0162] In order to achieve that purpose, according to a further embodiment of the present invention, It is arranged such that;  
     [0163] First, when the back member ( 31 ) is provided with a plurality of sensors (i.e. the hip sensor ( 33 ), spine sensor ( 37 ), and/or blade sensors ( 35 ), ( 35 ′)), the sensors may be comprised of weight detecting sensors which can detect the weight or pressing force of the occupant applied to said back member.  
     [0164] Second, a standard degree of pressing force for each sensor is preset and stored in memory. The standard degree of pressing force for any one sensor may be the same as that of the other sensor. However, it is preferable that the standard degree of pressing force preset for any one sensor (e.g. spine sensor ( 37 )) is different from that for the other sensor (e.g. hip sensor ( 33 )).  
     [0165] Third, the pressing force applied to each sensor is checked through a determination as to whether the pressing force exceeds the preset standard degree or not.  
     [0166] Fourth, when the pressing force applied to a sensor exceeds the standard degree, the microcomputer ( 91 ) orders the responding means ( 95 ) to produce responding signal.  
     [0167] It is preferable that the responding signal is an auditory signal to notify the occupant which sensor is under excessive pressure.  
     [0168] Fifth, when the responding means ( 95 ) produces responding signal, it is arranged such that the response is stopped when the occupant, upon recognizing the responding signal, reduces the pressing force applied to the sensor.  
     [0169] For example, if the spine sensor ( 37 ) is comprised of a weight detecting sensor, it, at first, merely generates/sends signals to the microcomputer ( 91 ) when an occupant contacts the sensor ( 37 ), and then, when the occupant leans the upper body part backward and the pressing force of the occupant&#39;s body exceeds the standard level of pressing force preset for the spine sensor ( 37 ), the microcomputer ( 91 ) perceiving the excessive pressure orders the responding means to produce responding signal, according to the predetermined program. When the responding means ( 95 ) responds, the occupant, upon recognizing the responding signal, tries to reduce the pressing force applied to the spine sensor ( 37 ) in order to stop the response. Thus, the weight of the upper body part of the occupant may evenly be dispersed to the back member and thereby the occupant can maintain the neutral spine position.  
     [0170] Further, the present invention may be of such arrangement that the microcomputer ( 91 ) maintains the responding means ( 95 ) in hold state for a short time, as a hold time, until certain standard time elapses, according to the predetermined program.  
     [0171] When an occupant sits on the sitting means of the present invention, he/she may simultaneously touch the sensors all at once and let the responding means ( 95 ) produce no responding signal at the moment he/she sits thereon. However, in most cases, the thigh bones are first laid on the seat member ( 21 ) contacting the seat sensor ( 23 ), and then the hip and small part touch the back member ( 31 ) contacting the hip sensor ( 33 ). Namely, there exists certain time period for all the signals to be sent to the microcomputer ( 91 ), and it is required to let the responding means ( 95 ) produce no responding signal during this time period.  
     [0172] Further, the occupant in a sitting means with the body contacting all the corresponding sensors for certain sensing mode provided thereof may feel necessary to remove certain part (e.g., upper part of the spinal column) of the body from the part of the sitting means to which said part of the body is contacting for a short time period, and thereupon does not contact the sensor (e.g. spine sensor) provided to said part of the sitting means.  
     [0173] However, if the responding means ( 95 ) responds at once the moment the occupant removes certain part of the body from the sitting means, and further the response occurs repeatedly whenever the occupant moves his/her body for a short time period, it not only is inconvenient but also makes the occupant unpleasant and nervous. Thus, it is also required to let the responding means ( 95 ) remain in hold state for a given standard time when an occupant removes certain part of his/her body from the sitting means.  
     [0174] Accordingly, it should be arranged that even if all the signals the numbers of which are the same as the preset number of the sensors are not sent to the microcomputer ( 91 ), the insufficiency of the time, not reaching the standard hold time, during which all the signals from the sensors are sent to the microcomputer ( 91 ), will defer the instruction of the microcomputer ( 91 ) to activate the responding means ( 95 ) and thus keep the responding means ( 95 ) in hold state. In short, the microcomputer ( 91 ) may be so programmed as to order the responding means ( 95 ) to remain in hold state for a given standard time, and after lapse of such hold time, the microcomputer ( 91 ) permits the responding means ( 95 ) to respond. A known time counting means, i.e., a timer (not shown) is provided for counting said standard hold time. The hold time may be approx. 3 sec., preferably.  
     [0175] The standard hold time may be altered to other desired time period such as 1 sec., 5 sec., 60 sec., and so forth. With these arrangements, it is possible to prevent the responding means to randomly generate responding signals when there exists certain time period for the occupant to contact all the corresponding sensors for certain sensing mode.  
     [0176] Now, with above explained sensing device of the present invention, a method for sensing the sitting posture of an occupant and encouraging the occupant to have optimum sitting posture will be described.  
     [0177] In FIG. 20, there is illustrated a main flow diagram of the processing procedures of the microcomputer ( 91 ). According thereto, at the block ( 80 ), the power supply switch is turned on and the flow of the processing step starts, as indicated by the next block ( 81 ), with an instruction to detect the presence of the signals generated by the sensors and sent to the microcomputer ( 91 ).  
     [0178] At the block ( 81 ), it is examined whether signals transmitted from the sensors exist or not, and determined either to put the responding means in non-responding state when there exists no signal sent by the sensors, or to let the step proceed to the next block ( 83 ) when there exists at least one signal.  
     [0179] It is noted here that normally, no signal is generated/sent to the microcomputer ( 91 ) when no one is sitting on the sitting means. Likewise, when the occupant sitting on the sitting means and contacting all the corresponding sensors for certain sensing mode stands up and does not contact any sensors, no signal is generated/sent to the microcomputer ( 91 ).  
     [0180] If no signal is detected, the “NO” is decided, thus putting the responding means ( 95 ) at the block ( 82 ) in non-responding state.  
     [0181] If, however, there exist at least one signal received; the block ( 81 ) answers “YES”, leading the step to the next block ( 83 ).  
     [0182] As described earlier, the number of sensors for certain sensing mode and the data for the signals of the sensors are preset and stored in memory for the microcomputer ( 91 ) to proceed the operations.  
     [0183] At the block ( 83 ), the step proceeds to compare the number of the signal(s) sent by the sensor(s) with the preset number of corresponding sensors for certain sensing mode, and to determine as to whether the number of signals coincides with the preset number of sensors or not.  
     [0184] If the number of signals coincides with the preset number of the sensors, the “YES” is decided, thus putting the responding means ( 95 ) at the block ( 82 ) in non-responding state. If the occupant does not contact any one sensor(s) or contacts it (them) a little late, as the number of signals does not coincide with the preset number of the sensors, the block ( 83 ) answers “NO”, leading the step to the next block ( 85 ). At the block ( 85 ), a timer (not shown) starts to count the preset 3 seconds of hold time.  
     [0185] The step is then led to determining at the block ( 87 ) as to whether the 3 seconds of hold time has lapsed, or not. At this stage, during such hold time, instruction in the microcomputer ( 91 ) repeatedly indicates a “NO” signal until the 3-sec. time period is over, to withhold decision.  
     [0186] Then, after lapse of the hold time, “YES” is decided at the block ( 87 ), so that, at block ( 87 ), instruction is given to cause said responding means at the block ( 89 ) to respond. During the hold time, if the occupant touches the sensor(s) that he/she at first did not touch, all the signals are sent to the block ( 81 ).  
     [0187] Accordingly, at the block ( 83 ), the number of the signals becomes coincident with the preset number of the sensors, and the “YES” is decided at the block ( 83 ), thus stopping the counting and putting the responding means ( 95 ) at the block ( 82 ) in non-responding state.  
     [0188] When the hold time has lapsed and the responding means ( 95 ) begins to produce responding signal, and if the occupant, upon apprehending the response of the responding means ( 95 ), contacts the sensor(s) which he/she at first did not contact, all the signals are sent to the block ( 81 ), and thereupon the number of the signals becomes coincident with the preset number of the sensors, the “YES” is decided at the block ( 83 ), thus stopping the response of the responding means ( 95 ) and putting the responding means ( 95 ) at the block ( 82 ) in non-responding state.  
     [0189] As above described, the occupant contacting all the corresponding sensors for certain sensing mode may feel necessary to remove certain part of the body from the part of the sitting means to which said part of the body is contacting for a short time period, and thereupon does not touch the sensor provided to said part of the sitting means.  
     [0190] In this case, the number of signals sent to the block ( 81 ) is less than the preset number of the sensors, and the flow of processing step again proceeds through the blocks ( 83 ), ( 85 ), ( 87 ) in the same fashion as described above.  
     [0191] In case of the above described “basic sensing mode” comprised of the hip sensor ( 33 ) and control unit ( 90 ), as only the hip sensor ( 33 ) is provided to the sitting means or selected among the sensors provided to the sitting means, the microcomputer ( 91 ) is programmed to include the following two different steps of operations.  
     [0192] When an occupant sits in the sitting means and contacts the hip sensor ( 33 ), the sensor ( 33 ) generates and sends signal to the microcomputer ( 91 ). Upon receiving the signal the number of which coincides with the preset number of the sensor ( 33 ), the microcomputer ( 91 ) let the responding means ( 95 ) remain in non-responding state in the same manner as described in connection with other sensing modes.  
     [0193] When the occupant removes the hip from the sensor ( 33 ), the sensor ( 33 ) stops generating/sending signal to the microcomputer ( 91 ), which, in the other sensing modes, means that as no signal is sent to the microcomputer ( 91 ), the microcomputer ( 91 ) puts the responding means ( 95 ) in non-responding state.  
     [0194] However, as the first different step of operation, when the sensor ( 33 ) stops sending signal for the first time, the miocrocomputer ( 91 ), even though there exists no signal sent thereto, orders the responding means ( 95 ) to produce responding signal to notify the occupant that he/she is not contacting the sensor ( 33 ).  
     [0195] When said responding means produces the responding signal, the occupant becomes aware that he/she does not contact said sensors. Immediately after the response, the occupant, upon recognizing the responding signal, corrects his/her sitting posture with the hip contacting the lower part of said back member by letting the hip be posteriorly and inferiorly positioned, and contacts said hip sensor within certain standard time period.  
     [0196] Thus, the signal of the sensor ( 33 ) is again sent to the microcomputer ( 91 ), and thereby the responding means ( 95 ) stops producing responding signal.  
     [0197] As the second different step of operation, if the occupant continuously does not contact the hip sensor ( 33 ) and thereby no signal is sent to the microcomputer ( 91 ) during a given standard time period, the microcomputer orders the responding means ( 95 ) to remain in non-responding state after the standard time period has elapsed.  
     [0198] With these arrangements, the present embodiment encourages and urges the occupant to have right sitting posture while studying or working during certain time period, and further permits the occupant to freely use the sitting means.  
     [0199] Through practical use of the devices and methods of the present invention heretofore explained, the faulty sitting posture of the occupant in a sitting means can be changed to a good one, the occupant can concentrate on his work without feeling any fatigue, discomfort, strain or lower back pains, and especially, children and teens can make it a habit to sit in the chairs in right sitting posture from their early days. In short, with the sensing device of the present invention, first, a person can make it a habit to sit in optimum sitting posture, second, he/she can have well built straight body, third, he/she can prevent chronic lumbar myalgia, excessive lordosis, kyphosis and scoliosis, drooping chest and round back, and fourth, he/she can have physiologic, erect posture even in his/her old age.  
     [0200] While having described the present invention thus far, it should be understood that the invention is not limited to the illustrated embodiments, but other various modifications, alterations and additions may be possible without departing from the spirits and scope of the appended claims.  
     [0201] For example, some sitting means have adjustable back members that can be moved to the lateral, vertical and fore-and-aft directions. The sensing device of the present invention can also be provided in combination with these types of sitting means.