Seat device having a function of retaining person's seated position

Abstract

A device for retaining a person's seated position is provided as seats for vehicles, for example. The device has a seat member and an upper body support member. The seat member has a seat surface on which a person is seated. The seat surface has a pair of reference ridges each of which is fit to a recess between a biceps femoris muscle and a semimembranosus muscle of each of thighs of the person. The upper body support member has an upper body support surface that supports an upper body back of the person. Various types of ridges are provided on the upper body support surfaces for stabilizing the upper body of the person seated on the seat.

What is claimed is: 
     
         1 . A seat device for retaining a person's seated position, comprising a seat member having a seat surface on which a person is seated, wherein the seat surface has a pair of reference ridges each of which is fit to a recess between a biceps femoris muscle and a semimembranosus muscle of each of thighs of the person. 
     
     
         2 . The seat device of  claim 1 , comprising an upper body support member having an upper body support surface that supports an upper body back of the person. 
     
     
         3 . The seat device of  claim 2 , wherein the upper body support surface has slant ridges for ribs, the slant ridges touching the ribs of the person from beneath and being slanted according to the ribs, the ribs descending with person's exhalation. 
     
     
         4 . The seat device of  claim 3 , wherein the slant ridges are formed to touch a person's upper body back between a ninth rib and a tenth rib of the ribs. 
     
     
         5 . The seat device of  claim 2 , wherein the upper body support surface has aid ridges for shoulder blades, the aid ridges i) being located to be fit to a range of fifth to seventh ribs of the ribs in a vertical direction of the seat member, ii) being substantially horizontal to the seat surface, and iii) being located such that a length from a center line of the upper body support surface in a width direction thereof to a center-line-side end of each of the aid ridges is equal to or larger than a length from a backbone center line to a backbone end of the person and equal to or smaller than a length from the backbone center line to a shoulder blade of the person. 
     
     
         6 . The seat device of  claim 5 , wherein the upper body support surface has horizontal ridges for lower ribs, the horizontal ridges i) being located to be fit to a range of tenth to twelfth ribs of the ribs in the vertical direction and ii) being substantially horizontal to the seat surface. 
     
     
         7 . The seat device of  claim 2 , wherein the upper body support surface has a pair of support projections for ilia, which are fit to a pair of ilium projections of the person, the ilium projections being projected rearward when the person is seated on the seat surface of the seat member, and
 wherein the seat surface has a pair of accommodating recesses for ischiums, which accommodates therein a pair of ischium projected portions of the person, the ischium projected portions being projected downward.   
     
     
         8 . The seat device of  claim 3 , wherein the upper body support member is configured such that at least an upper part of the upper body support member is movable to the seat surface in the vertical direction, the upper part being higher than lower ends of the slant ridges for the ribs. 
     
     
         9 . The seat device of  claim 5 , wherein the upper body support member is configured such that at least an upper part of the upper body support member is movable to the seat surface in the vertical direction, the upper part being higher than lower ends of the aid ridges for the shoulder blades. 
     
     
         10 . The seat device of  claim 6 , wherein the upper body support member is configured such that at least an upper part of the upper body support member is movable to the seat surface in the vertical direction, the upper part being higher than lower ends of the horizontal ridges for the lower ribs. 
     
     
         11 . The seat device of  claim 2 , wherein the upper body support surface has a pair of slant ridges which are slanted at an angle substantially equal to an inclination angle of the ninth or tenth rib of the person, the slant ridges being located on both sides of a center line of the upper body support surface in a width direction thereof and being slanted as advancing from the center line, and
 wherein the upper body support member is configured such that at least an upper part of the upper body support member is movable to the seat surface in the vertical direction, the upper part being higher than lower ends of the pair of slant ridges.   
     
     
         12 . The seat device of  claim 2 , wherein the upper body support surface has a pair of substantially horizontal ridges which are located on both sides of a center line of the upper body support surface in a width direction thereof, and
 wherein the upper body support member is configured such that at least an upper part of the upper body support member is movable to the seat surface in the vertical direction, the upper part being higher than lower ends of the pair of substantially horizontal ridges.   
     
     
         13 . The seat device of  claim 12 , wherein the upper body support surface has a pair of slant ridges which are slanted at an angle substantially equal to an inclination angle of the ninth or tenth rib of the person, the slant ridges being located on both sides of a center line of the upper body support surface in a width direction thereof and being slanted as advancing from the center line, and
 wherein the upper body support surface has pairs of substantially horizontal ridges which are located on both sides of the center line of the upper body support surface in the width direction thereof and located on both upper and lower sides of the pair of slant ridges in the vertical direction.   
     
     
         14 . The seat device of  claim 8 , wherein the upper body support surface has a pair of support projections for ilia, which are fit to a pair of ilium projections of the person,
 the seat surface has a pair of accommodating recesses for ischiums, which accommodates therein a pair of ischium projected portions of ischia of the person, and   the upper body support member has a portion in which the pair of support projections for the ilia are provided on the upper body support surface, the portion of the upper body support member being inseparable from the seat member providing the seat surface.   
     
     
         15 . A device for retaining a person's seated position, having a seat surface on which a person is seated, wherein the seat surface has a pair of reference ridges each of which is fit to a recess between a biceps femoris muscle and a semimembranosus muscle of each of thighs of the person. 
     
     
         16 . The device of  claim 15 , having an upper body support surface that supports an upper body back of the person. 
     
     
         17 . The device of  claim 16 , wherein the upper body support surface has slant ridges for ribs, the slant ridges touching the ribs of the person from beneath and being slanted according to the ribs, the ribs descending with person's exhalation. 
     
     
         18 . The device of  claim 17 , wherein the slant ridges are formed to touch a person's upper body back between a ninth rib and a tenth rib of the ribs. 
     
     
         19 . The device of  claim 16 , wherein the upper body support surface has aid ridges for shoulder blades, the aid ridges i) being located to be fit to a range of fifth to seventh ribs of the ribs in a vertical direction of the seat member, ii) being substantially horizontal to the seat surface, and iii) being located such that a length from a center line of the upper body support surface in a width direction thereof to a center-line-side end of each of the aid ridges is equal to or larger than a length from a backbone center line to a backbone end of the person and equal to or smaller than a length from the backbone center line to a shoulder blade of the person. 
     
     
         20 . The device of  claim 19 , wherein the upper body support surface has horizontal ridges for lower ribs, the horizontal ridges i) being located to be fit to a range of tenth to twelfth ribs of the ribs in the vertical direction and ii) being substantially horizontal to the seat surface. 
     
     
         21 . The device of  claim 16 , wherein the upper body support surface has a pair of support projections for ilia, which are fit to a pair of ilium projections of the person, the ilium projections being projected rearward when the person is seated on the seat surface of the seat member, and
 wherein the seat surface has a pair of accommodating recesses for ischiums, which accommodates therein a pair of ischium projected portions of the person, the ischium projected portions being projected downward.