GB2370359A

GB2370359A - Method of evaluating seat comfort

Info

Publication number: GB2370359A
Application number: GB0031505A
Authority: GB
Inventors: Kazushige Ebe; Michael J Griffin
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 2000-12-22
Filing date: 2000-12-22
Publication date: 2002-06-26
Also published as: JP2002195900A; GB0031505D0; JP4888621B2

Abstract

Disclosed is a method of evaluating a sitting comfort of a seat to be inspected, including the steps of: applying a specific load to the seat; measuring a pressure applied to each measurement point of the seat; and evaluating a sitting comfort of the seat on the basis of the calculated weights; wherein a subject is sit, and a sitting comfort of the seat is evaluated on the basis of the total of weights applied to a peak area, the peak area being defined by a partial region, including a deepest point of recess of the seat. With this evaluating method, not only a static sitting comfort of a seat can be simply quantified, but also sitting comfort of various seats can be simply, certainly evaluated.

Description

Method of Evaluating Sitting Comfort of Seat

The present invention relates to a method Of quantitatively evaluating a static sitting comfort of a seat, and particularly to a new method of evaluating a sitting comfort of a seat, which is capable of simply, and reliably evaluating a sitting comfort of a seat on the basis of the total of weights in a specific area which exerts an effect on the sitting comfort.

Conventionally, a so-called"bottoming feeling"due to a phenomenon that a cushion material is largely deformed and crushed to thereby rapidly lose its elastic characteristic has been regarded as one factor exerting a large effect on a static sitting comfort of a seat ; and a so-called"hardness feeling"due to a hardness inherent to the cushion material has been regarded as another factor.

It has been considered that each of the"bottoming feeling"and"hardness feeling"is generally concerned with a sitting pressure applied to a portion of a seat, positioned directly under an ischial tuberosity of a person sitting on the seat, and thereby a static sitting comfort of a seat can be generally estimated by measuring the abovedescribed sitting pressure applied to a portion of the seat, positioned directly under an ischial tuberosity of a person sitting on the seat.

Methods of evaluating a sitting comfort of a seat have been proposed, for example, in Japanese Patent Laid-open No.

Hei 9-218115 entitled"Method of Quantitatively Measuring Pressure Comfort of Seat Cushion", and Japanese Patent Laidopen No. Hei 10-274577 entitled"Contact Gap Evaluating Method".

To quantitatively estimate a sitting comfort of a seat on the basis of a measured sitting pressure distribution,

each of these methods is required to compensate a sitting pressure value measured at each measurement point with a factor concerned with human sensation. Concretely, the measured sitting pressures at portions of a cushion member, being in contact with portions of a human body different from each other in pressure sensation such as an ischial tuber, thighs, and coccyx, are multiplied by the corresponding weighting factors, and the weighted pressure values are integrated over the entire contact area of the cushion member, or the total of each of groups of the weighted pressure values in specific regions, divided from each other, of the cushion member is calculated. In the case of comparing two seats, which are different in shape, with each other, these seats may be sometimes largely different from each other in terms of the pattern of the sitting pressure distribution. From this viewpoint, the calculation of the sitting pressure distribution over the contact area based on the weighted pressure values, adopted by the above-described method, seems to be effective as one method of quantifying the sitting pressure distribution.

The above-described method, however, has a problem that it requires a complicated work, that is, a work of weighting the measured sitting pressures at different portions of a seat. In fact, it takes a lot of labor to

multiply the measured sitting pressures by the corresponding weighting factors by using specialized software. Further, if a seat A is compared with a seat B in which the pad shape is the same as that of the seat A and the hardness and the cushion material are higher than those of the seat A, there is not a large difference between the seats A and B in terms of the pattern of a pressure distribution over the contact area, but there may be a significant difference between the seats A and B in terms of the pattern of a pressure distribution at that area of the seat including a highest pressure portion being in contact with an ischial tuberosity of a person sitting on the seat.

As described above, according to the prior art method, since the evaluation steps are complicated, it takes a lot of labor to evaluate a sitting comfort of a seat, and since the evaluation is performed for a selected seat, such a method is not suitable as a method of evaluating seats especially when the seat shape is the same.

An object of the present invention is to quantify a static sitting comfort of a seat, and to provide a new

method of simply, certainly evaluating a sitting comfort of , a seat on the basis of the total of weights in a specific region which exerts an effect on the sitting comfort.

The present inventors have repeated experiments performed by dividing a partial region, to which a sitting load is applied, of a seat into some areas measuring the pressures of each area and calculating the total of weights applied to each area, while performing a subjective evaluation to a sitting comfort of the seat, and found that there is a correlation between the total of weights applied to a specific area and a sitting comfort of a seat.

The present inventor has focused attention on a recess of a seat as a factor of determining the above-described specific area. More specifically, when a subject is sit on a seat to be inspected, a partial region, to which a sitting load is applied, of the seat is downwardly recessed. In this case, points of the downwardly curved recess, pressed by the buttocks directly under the ischiatic tuber of the subject, become deepest. The present inventor has specified a small partial region including these deepest points of the recess as a peak area and further divided the total region of the recess into a plurality of areas on the basis of the

peak area, and calculated the total of weights applied to each area. On the other hand, the present inventor has performed the subjective evaluation of a sitting comfort of the seat by the subject.

As a result, the present inventor has found that the subjective evaluation of a sitting comfort of a seat (hereinafter, referred to as a"comfort score") has a correlation only with the total of weights applied to the

above-described peak area, and has no correlation with any other area than the peak area and a wide partial region including the peak area, and that the total of weights applied to the peak area can be adopted as a criterion of evaluating a sitting comfort of a seat, especially when the shape of seats are the same or similar.

The present inventor has also found that in the case of specifying a peak area by using a subject, it is desirable to set the total area of the peak area in a range of 0.05 to 150 cm2 for certainly evaluating a sitting comfort of a seat.

The present invention has been accomplished on the basis of the above-described knowledge.

Accordingly, the present invention provides a method of evaluating a sitting comfort of a seat to be inspected, including the steps of: applying a specific load to the seat ; measuring a pressure applied to each measurement point of the seat; and evaluating a sitting comfort of the seat on the basis of the measured pressures; wherein a subject is sit on the seat, and the sitting comfort of the seat is evaluated on the basis of the total of the weights applied

on a peak area, the peak area being defined by a partial region, including a largest recess, of the seat.

In the above-described method, preferably, in the case of specifying the peak area by sitting a subject on the seat, the total area of the peak area is in a range of 0.05 to 150

2 cm With this evaluation method of the present invention, it is possible to simply quantify a static sitting comfort of the seat, and to simply, certainly evaluate sitting comfort of various seats.

BREIF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view illustrating one example of a seat pressure sensing mat used in an evaluating method of the present invention; Fig. 2 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a circular shape; Fig. 3 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a vertically-elongated elliptic shape; Fig. 4 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a horizontally-elongated elliptic shape; Fig. 5 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a cruciform shape; Fig. 6 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a square shape ; Fig. 7 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a rhombic shape ; Fig. 8 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a rectangular shape ; Fig. 9 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a regular triangular shape;

Fig. 10 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions, each of which is formed into a regular hexagonal shape; Fig. 11 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions connected to each other into a gourd shape; Fig. 12 is a front view of only a recess of a seat caused when a subject sits on the seat, wherein a peak area A is specified by two graphic regions connected to each other into a reversed U-shape ; Fig. 13 is diagram of a sitting pressure distribution for illustrating an example of dividing a recessed region, to which a load of a subject is applied, of a seat into some areas in Example 1; Fig. 14 is a graph showing a relationship between the total of sitting weights applied to an area (peak area) A and a comfort score for each foam sample shown in Table 1 in Example 1 ;

In Fig. 15 is a graph showing a relationship between the total of sitting weights applied to an area B (larger than the area A) and a comfort score for each foam sample shown in Table 1 in Example 1; Fig. 16 is a graph showing a relationship between the total of sitting weights applied to an area C (a sitting pressure region pressed by the buttocks excluding a sitting pressure region pressed by the thighs) and a comfort score for each foam sample shown in Table 1 in Example 1; Fig. 17 is a graph showing a relationship between the total of sitting weights applied to an area D (a sitting pressure region pressed by the thighs) and a comfort score for each foam sample shown in Table 1 in Example 1 ; and Fig. 18 is a graph showing a relationship between the total of sitting weights applied to an area (peak area) A and a comfort score for each of foam samples different from each other only in thickness.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter preferences, options and explanations are given in further detail with reference to the accompanying drawings.

A new method of evaluating a sitting comfort of a seat, which is based on the findings of the present inventors, involves sitting a subject on a seat to be inspected, measuring a sitting pressure distribution, calculating the total of weights applied to a peak area defined as a partial region including the deepest point of a recess of the seat and its neighborhood, and evaluating the sitting comfort of the seat on the basis of the total of weights calculated from the pressures applied to the peak area.

The peak area in the present invention is specified for each seat placed at a specific orientation. The method of placing a seat to be inspected is not particularly limited, and in general, the seat may be placed, typically, with its backrest tilted at a specific angle (torso angle).

A subject is sit on the seat thus placed at the specific position on the seat. In the case of specifying a peak area by sitting a subject on the seat, since a position of a peak area and sitting pressures applied to the peak area differ depending on the body dimensions and posture of the subject, the peak area usually needs to be specified for each subject.

The peak area used in the present invention is specified on the basis of a highest pressure (peak value) measurement portion, that is, the deepest portion, of a recess of a seat, which recess is caused when the seat is pressed by a subject.

The seat pressed by the subject is recessed irrespective of the hardness, foam density, and the like of the seat. In this case, the recessed degree of an area of the seat is dependent on by which portion of the subject buttocks the area is pressed.

In the case of specifying the peak area of the present invention by a subject, the peak value measurement point

necessary for specifying the peak area is positioned directly under the ischiatic tuber of the subject, more specifically, directly under the projections of the buttocks of the subject. In this case, the weight of the subject is most applied, that is, the highest sitting pressure is applied to such a point, and therefore, the point is equivalent to the deepest point of the recess.

The peak value used in the present invention can be measured by a known method using, for example, a measurement apparatus capable of detecting a pressure distribution over the entire surface of a seat mounted on the measurement apparatus. Such a measurement apparatus is exemplified by a seat pressure sensing mat.

A seat pressure sensing mat will be described with reference to Fig. 1. A seat pressure sensing mat 1 includes a mat main body 2 for measuring pressures, a computer 3 for processing a pressure data measured by the mat main body 2, and an A/D converter 4. Pressures applied to a seat are detected at each measurement point by the mat main body 2.

The pressure data is converted by the A/D converter 4, and is processed by the computer 3, to thus examine a pressure distribution over the surface of the seat.

The mat main body 2 is formed into a square seat shape, and a pressure-sensitive region 5, which is surrounded by a broken line in Fig. 1, is defined on the upper surface of the mat main body 2. A matrix of vertical and horizontal lines coated with pressure-sensitive ink 6 is formed on the pressure-sensitive region 5. The intersections between the vertical and horizontal pressure-sensitive lines rm measurement points. It should be noted that although only part of the matrix is shown in Fig. 1, the matrix is actually formed on the entire pressure-sensitive region 5.

A peak value measurement point of a seat to be inspected is examined by using the seat pressure sensing mat 1 in accordance with the following procedure. First, the mat main body 2 is placed on the seat. In this case, the

backrest of the seat is tilted at the above-described specific angle (torso angle).

A subject is sit on the mat main body thus placed on the seat. On the seat pressed by the subject, the recessed shape differs at each pressed point ; however, since the pressure is measured for each measurement point in the pressure-sensitive region, it is possible to determine a point, at which a peak value is measured, on the seat by obtaining a pressure distribution applied to the seat from the data for each measurement point and processing the pressure distribution.

The peak area of the present invention is specified as a region including a peak value (highest pressure) measurement point determined by the above pressure distribution. The peak area is an area including a peak value measurement point which differs depending on the subject.

The peak value measurement point necessary for specifying the peak area of the present invention can be determined by the above pressure distribution. In the strict sense, there appear two peak value measurement points on a seat to be inspected.

To be more specific, the above sitting pressure distribution on the seat is derived from a load of a subject, and therefore, the sitting pressure distribution has two peak value measurement points at two right and left positions corresponding to both the buttocks directly under the ischiatic tuber of the subject. In this way, there appear two peak value measurement points on the seat.

However, since these peak value measurement points are almost bilaterally symmetric with respect to the body center line of a subject and generally receive the similar highest sitting pressure, the peak area may be specified by adopting at least one of the peak value measurement points as long as using either right peak only or left peak only.

Accordingly, the peak value measurement point used in the present invention means at least one of the above

described two peak value measurement points, and the peak area used in the present invention is defined as an area including at least one of the above-described two peak value measurement points. In this case, the peak area including both the peak value measurement points or the peak area including either of the peak value measurement points may be selectively adopted in accordance with various conditions such as a measurement condition upon evaluation.

The peak area used in the present invention is, as described above, defined as a partial region including the deepest point of a recess of a seat and its neighborhood, and the total area of the peak area is not particularly limited but may be preferably specified in the case of specifying the peak area by a subject.

According to the present invention, in the case of specifying the peak area by a subject, it may be preferable to numerically specify the total area of the peak area. For example, in the case of adopting the peak area including right and left two peak value measurement points, the total area of the peak area may be in a range of 0.1 to 150 cm2, preferably, 1 to 100 cm2, more preferably, 1 to 50 cm2. In the case of adopting the peak area including one peak value measurement point, the total area of the peak area may be a half of the above-described total area, that is, in a range of 0.05 to 75 cm2, preferably, 0.5 to 50 cm2, more preferably, 0.5 to 25 cm2. As the total area of the peak area becomes smaller, the peak area comes nearer to the peak value measurement point. On the other hand, if the total area of the peak area becomes excessively large, the total of weights applied to the peak area may be less well correlated with the evaluation result of a sitting comfort because the correlation is largely affected by other factors besides the peak value measurement point.

The shape of the peak area used in the present invention is not particularly limited insofar as it includes either or both of the above-described peak value measurement points, that is, the deepest points of a recess of a seat.

The peak area, however, may be formed into right and left two symmetric graphic (for example, circular, elliptic, or polygonal) regions which include the right and left two peak value measurement points and which are identical to or different from each other, or may be formed into one region in which the right and left two symmetric graphic regions including the right and left two peak value measurement points are connected to each other. In the case of adopting the peak area including only one peak value measurement point, the peak area may be formed into the same graphic region as that described above, that is, the circular, elliptic, or polygonal region including the peak value measurement point. In each case, one or two peak value measurement points may be preferably located at the central portion of the peak area.

The pressure is determined, for example, by using a seat pressure sensing mat sold by Nitta K. K. in the trade name of (Tech Scan"BIG MAT"). The pressure-sensitive region of the mat has a grid-like matrix coated with pressure-sensitive ink. Matrix includes longitudinal lines having a predetermined width spaced at predetermined intervals and lateral lines having a predetermined width spaced at predetermined intervals. The intersections between these lines form measurement points.

The loaded weight of a partial region which is determined so that each measuring point is included in the partial region is obtained from the measured pressure at the point and the area of the partial region. The loaded weight of the peak area is obtained from the total of the weight of the partial regions included in the peak area.

Various shapes of peak area usable in the present invention will be described in further detail with reference to Figs. 2 to 12. Each of Figs. 2 to 12 is a front view showing only a recessed portion caused when a subject sits on a seat to be inspected, wherein a peak area is specified by a graphic region A.

Figs. 2 to 10 each shows a peak area specified by two graphic regions A which are identical to each other and which include two peak value measurement points, wherein Fig.

2 shows a peak area specified by two circular regions; Fig.

3 shows a peak area specified by two vertically-elongated elliptic regions; Fig. 4 shows a peak area specified by two horizontally-elongated elliptic regions; Fig. 5 shows a peak area specified by two cruciform regions; Fig. 6 shows a peak area specified by two square regions ; Fig. 7 shows a peak area specified by two rhombic regions; Fig. 8 shows a peak area specified by two rectangular regions; Fig. 9 shows a peak area specified by two regular triangular regions; and Fig. 10 shows a peak area specified by two regular hexagonal regions. In the example shown in the figure, the peak area is specified by two graphic regions including two peak value measurement points ; however, in the case of adopting the peak area including only one peak value measurement point, the peak area may be specified by one of the corresponding two graphic regions shown in the figure.

Figs. 11 and 12 each shows a peak area specified by two graphic regions A including two peak value measurement points, which graphic regions are bilaterally symmetrically connected to each other, wherein Fig. 11 shows a peak area specified by two circular regions connected to each other into a gourd shape, and Fig. 12 shows a peak area specified by two graphic regions connected to each other into a reverse U-shape. In particular, by adopting the peak area formed into the reverse U-shape shown in Fig. 12, a sitting comfort of a seat can be evaluated in consideration of the effect of the coccyx portion in addition to the effect of the ischiatic tuber of a subject.

The shapes of the peak area used in the present invention are not limited to those shown in Figs. 2 to 10 but may be other shapes.

The method of evaluating a sitting comfort of a seat according to the present invention is carried out by specifying a peak area in accordance with the above

described manner, calculating the total of weights applied to the peak area, and evaluating the sitting comfort on the basis of the total of the weights applied to the peak area.

More specifically, the evaluation method of the present invention is performed by sitting a subject on a seat to be inspected, measuring the pressure and calculating the total of weights applied to the above-described peak area, and evaluating the sitting comfort on the basis of the total of weights applied to the peak area. In this case, the calculation of the total of weights applied to the peak area can be performed by using a measurement apparatus such as the above-described seat pressure sensing mat ; however, the measurement apparatus, measurement conditions, and the like for calculating the total of weights applied to the peak area are not particularly limited.

According to the evaluation method of the present invention, by calculating the total of weights applied to the peak area of each of the seats to be compared with each other, the sitting comfort of the seat in which the total of weights applied to the peak area is high is evaluated to be poor, and the sitting comfort of the seat in which the total of weights applied to the peak area is low is evaluated to be good.

As a result, according to the method of the present invention, in the case of calculating the total of weights applied to the peak area by adopting a subject, the sitting

comfort of the seat can be simply, certainly evaluated by specifying a peak area of each of seats to be compared with each other, calculating the total of weights applied to the peak area of each of the seats to be compared with each other, and comparing them with each other.

The evaluation method of the present invention is not affected by characteristics, such as thickness or hardness of the foam, of a seat as long as the shape of a seat surface is the same or similar, and accordingly such a method can be suitably adopted as a method of relatively evaluating a sitting comfort of seat, and to simply,

certainly evaluating a sitting comfort of various seats unlike the prior art evaluation method affected by the hardness, density, thickness, and the like of a seat to be inspected.

Hereinafter, the method of evaluating a sitting comfort of a seat according to the present invention will be described in detail by way of, while not limited thereto,

the following examples : EXAMPLE Example 1 Five kinds of polyurethane foam samples (1) to (5) shown in Table 1, each having the same rectangular size (500 mm x500 mm xlOO mm), were evaluated in accordance with the method of the present invention. The hardness (ISO-2439) and density of each polyurethane foam sample are shown in Table 1.

Table 1

25%ILD hardness Density Sample No. (N) (kg/m3) (1) 120 43 (2) 156 47 (3) 206 52 (4) 247 57 (5) 285 63 A peak area including a peak value measurement point was specified for each seat sample. The peak value measurement point was determined by using a seat pressure sensing mat having a pressure-sensitive region of a size (length: 480 mm, width: 440 mm, thickness: about 1 mm), sold by Nitta K. K. in the trade name of (Tech Scan"BIG MAT").

The pressure-sensitive region of the mat has a grid-like matrix coated with pressure-sensitive ink. The matrix includes longitudinal lines (width: 5 mm) spaced at

intervals of 10 mm and lateral lines (width : 5 mm) spaced at intervals of 10 mm. The intersections between these lines form measurement points.

The loaded weight of a partial region which is determined so that each measuring point is included in the partial region is obtained from the measured pressure of the point and the area of the partial region. The loaded weight of the peak area is obtained from the total of the weight of the partial regions included in the peak area.

The seat pressure sensing mat was placed on each seat sample with its backrest adjusted at a specific angle (torso angle).

Each of twelve subjects, whose characteristics were shown in Table 2, was sit on the foam sample thus placed on the seat pressure sensing mat. The sitting pressure distribution of the foam sample was then examined for each subject.

Table 2

age weight (kg) height (cm) average 28. 7 73.5 177.5 max. 36 84.0 183.0 min. 22 62.0 167.0 standard deviation 4.5 6.3 4.5 To qualify sitting pressures applied to a seat by a load of each subject, a sitting pressure distribution of the seat was, as shown in Fig. 13, divided into four rectangular areas A, B, C and D, and the total of sitting weights applied to each area was calculated. It should be noted that Fig. 13 shows one example in which a pressure distribution applied to the seat by a load of one subject is divided into areas. While not shown, the same procedure was performed for each of the remaining eleven subjects. In

this case, two square regions (4 cm x 4 cm), each including

a peak value (highest sitting pressure) measurements point of the seat, are taken as the area (or peak area) A ; two square regions (10 cm x 10 cm), each including the peak value measurement point and being larger than the square region (4 cm x 4 cm) of the area A, are taken as the area B ; a sitting pressure region pressed by the buttocks of the subject and positioned around the area B (excluding a portion pressed by the thighs of the subject) is taken as the area C; and a sitting pressure region pressed by the thighs of the subject is taken as the area D.

In this case, since the subjects are different from each other in body dimensions, the positions of the areas A, B, C and D differ for each subject. However, each of the areas A and B can be easily determined on the basis of the peak value measurement point ; the area C can be easily determined as an entire sitting pressure region pressed by the buttocks of the subject, which region includes the areas A and B and excludes the region pressed by the thighs ; and the area D, which is equivalent to the region pressed by only by the thighs, can be easily determined on the basis of the areas A and B.

On the other hand, each sample was subjectively evaluated for sitting comfort by a paired comparison method.

The comparison method is performed by arbitrarily picking up two kinds of the samples, comparatively evaluating the sitting comfort of the two samples, repeating such evaluation for all combinations between the samples, and relatively evaluating, on the basis of the evaluation result, the sitting comfort of all the samples.

The sensory evaluation of the above paired comparison method is performed by a manner of sitting a subject on each of seats to be compared with each other, and comparing the sitting comfort of the seats with each other by the subject on the basis of seven evaluation scales (+3, +2, +1, 0,-1, - 2,-3). The evaluation scales are used for determining a numerical difference between the seats to be compared with each other. As the numerical difference between the samples

becomes larger, the difference in sitting comfort between the samples becomes larger. On the contrary, as the numeral difference between the samples becomes smaller (the numeral becomes zero or a value near zero), the difference in sitting comfort between the samples becomes smaller.

Further, as the numeral becomes larger, the sitting comfort becomes better, while the numeral becomes smaller, the sitting comfort becomes poorer.

Figs. 14 to 17 each show a relationship between the result of subjective evaluation of a sitting comfort of the seat (comfort score) and the total of sitting weights applied to each of the areas A, B, C and D of the seat. In addition, the total of weights applied to each area is an average value of the totals of weights in evaluation by the twelve subjects.

The results shown in Figs. 14 to 17 showed that the total of the sitting weights applied to each of the areas A and B of the present invention is highly correlated with the comfort score, that is, has a reliable correlation with the comfort score. Further, it was revealed that the graph of each of the areas A and B is tilted rightwardly, downwardly, that is, has a negative correlation with the comfort score.

This means that as the total of the weights applied to each of the areas A and B becomes larger, the comfort score becomes smaller, that is, the sitting comfort becomes poorer.

In the graph of the area A shown in Fig. 14, the multiple correlation coefficient R2 is 0.850, and the p value is 0.026. This means that the total of the weights applied to the area A has a high correlation with the comfort score.

In the graph of the area B shown in Fig. 15, the multiple correlation coefficient R2 is 0.487, and the p value is 0.190. This means that the total of the weights applied to the area B has a relatively high correlation with the comfort score, although the degree of correlation is slightly poorer than the degree of correlation in the graph of the area A.

The total of the weights applied to the area A including the peak value measurement point has a higher correlation with the comfort score as compared with the total of the weights applied to the area B including the peak value measurement point, which area is wider than the area A. This means that as the area of the peak area comes nearer to the peak value measurement point, the degree of correlation with the comfort score becomes higher.

On the contrary, in the graph showing the relationship between the total of the sitting weights applied to each of the areas C and D and the comfort score, the R2 value is low and the p value is high, and accordingly, the total of the sitting weights applied to each of the areas C and D has no correlation with the comfort score.

The graph shown in each of Figs. 14 and 15 in Example 1 can be used for estimating a sitting comfort of an arbitrary seat sample to be inspected. For example, by calculating the total of weights applied to the peak area of a seat sample to be inspected under the same condition as that in Example 1, a sitting comfort of the seat sample can be estimated by comparing the data of the seat sample with the data of the form sample evaluated in Example 1.

Example 2 Four kinds of polyurethane foam samples, having the same rectangular shape (500 mm x 500 mm) as that in Example 1 but various thicknesses (50 mm, 70 mm, 100 mm, and 120 mm), were used. Each polyurethane foam sample was tested by sitting each of the twelve subjects shown in Table 2 on the sample like Example 1, to calculate the total of sitting weights applied to an area A (peak area, square region (4 cm x 4 cm)) of the sample.

Each polyurethane foam sample was then subjectively evaluated for sitting comfort by each of the twelve subjects in accordance with the same paired comparison method as that in Example 1.

Fig. 18 shows a relationship between the total of weights applied to the area A of each of the samples (thickness: 50 mm, 70 mm, 100 mm, 120 mm) and the result of subjective evaluation of the sitting comfort of the sample by the subjects. The result in Fig. 18 showed that the total of the weights applied to the peak area A, in line with the present concepts, again had a high correlation with the comfort score. Accordingly, when the total of the sitting weights applied to the peak area A is lower, the comfort score is higher. This means that the sitting comfort is good. On the contrast, when the total of the sitting weights applied to the peak area A is higher, the comfort score is lower. This means that the sitting comfort is poor.

The graph shown in Fig. 18 used in Example 2 can be used for estimating a sitting comfort of an arbitrary seat sample to be inspected. For example, by measuring the total of weights applied to the peak area of a seat sample to be inspected under the same condition as that in Example 2, a sitting comfort of the seat sample can be estimated by comparing the data of the seat sample with the data of the form sample evaluated in Example 2.

Claims

CLAIMS :

1. A method of evaluating a sitting comfort of a seat to be inspected, comprising the steps of: applying a specific load to said seat; measuring a pressure applied to each measurement point of said seat ; and evaluating a sitting comfort of said seat on the basis of the measured pressures ; wherein a subject is sit on said seat, and a sitting comfort of said seat is evaluated on the basis of the total of weights applied to a peak area, said peak area being defined by a partial region, including a deepest point of recess of said seat.

2. A method of evaluating a sitting comfort of a seat to be inspected according to claim 1, wherein in the case of specifying said peak area by sitting a subject on said seat, the total area of said peak area is in a range of 0.05 to 150 cm2.