KR20050111615A - Swing stowed-type chair - Google Patents

Abstract

A seating portion 2 having a base 1 fixed to a floor or a desk, a backrest 2a and a seat 2b integrally coupled to each other, and a lower end and an upper end of the base and the seating part in the front and rear directions The rear leg portion 7 which is pivotally connected to the front leg portion and the base and the seating portion so that the lower end portion and the upper end portion can be swinged forward and backward, and the oscillation axis of the upper and lower ends thereof is located behind the swing axis of the upper and lower ends of the front leg portion. And a stopper structure 11 for restricting the swings of the base and the seating portions of the anterior leg and the rear leg to a certain range, the anterior leg and the rear leg forming a non-parallel 4 link, and at the rear oscillation restriction position. The seating part is arranged so that the seat and the backrest are in the use posture, while the seating part is arranged so that the seat and the backrest are inclined forward in the front swing restriction position, and the stopper structure By contacting the shaft 10 with the shaft 11, the rear swing limiting position of the front leg portion and the rear leg portion is regulated in response to the state where the base is inclined forward and inclined. Thereby, even if it installs in the place which inclined forward and inclined, a sitting part can be made into a use posture in a rear swing restriction position.

Description

Swinging retractable chair {SWING STOWED-TYPE CHAIR}

The present invention is a chair used in combination with a desk, and when not in use, the seating part swings forward from the use position behind the desk so that at least a seat of the seating part is placed on the upper plate of the desk. It relates to a swing-type chair accommodated in the lower portion. In addition, in this specification, "front" and "rear" mean the front and rear based on the direction of a chair. That is, the direction in which the backrest is located with respect to the center part of the sheet is called rear, and the direction opposite to it is called front.

As the chair as described above, for example, one disclosed in Japanese Patent Laid-Open No. 2002-028043 has been known. The swing-type reclining chair has a seating portion having a base fixed horizontally on a floor or a desk, such as a classroom, and a backrest and a seat integrally coupled to each other, and a lower end portion is pivotably connected to the base, respectively. In addition, the upper and lower end portions of the seating portion are connected to each other in front and rear directions so that the front and rear portions and the rear portions, which form a non-parallel four-way link, are regulated to a certain range. It has a fluctuation control department.

According to such a conventional swing retractable chair, the front leg and the rear leg constitute a non-parallel section 4 link, so that the front leg and the rear leg where the swing is restricted by the rock restraint are positioned at the rear swing limit position. In the seat, the seat and the back that are integrally coupled to each other in the seating portion are in a use posture in which the seat back is inclined slightly rearward and the seat is generally horizontal, so that a person can be seated in the seating area, while those front sides In the state where the rear and rear corner portions are located at the front swing limit position, the seat and the backrest of the seating portion are inclined forward and the at least seat of the seating portion can be stored in the lower portion of the upper plate of the desk.

Furthermore, in the state where the front and rear legs are located at the front swing limit position, the backrest of the seat is also inclined forward, so that when a person tries to pass the rear of the chair, Even if the height of the lower part of the back and the upper part of the backrest of the seating part generally coincide, the upper part of the backrest does not correspond to the part of the waist, so that the backrest of the seating part does not interfere with human traffic, People can pass very easily.

By the way, the inventor of the present invention has conducted further studies on the above-described conventional rocking chair, but the present inventors have installed the rocking chair in a place where the floor is inclined forward and inclined in a large classroom of a school. In this conventional swing-away chair, the tilting control part regulates the rear swing limit position on the premise that the base is fixed horizontally to a floor or a desk. When the base is fixed in the inclined state, the front and rear legs are inclined slightly backwards at the rear swing home position, and the seat is not in a horizontal position, and the seat is inclined forward. It was found that there was irrationality.

1 (a) and (b) show an embodiment of the swingable retractable chair of the present invention in a state in which the base is inclined forward and inclined and the front and rear portions are located at the rear swing restriction position. Fig. And side view.

2 (a) and 2 (b) are a plan view and a bottom view showing the chair of the embodiment in the same state as in FIG.

3 (a) and 3 (b) show the chair of the above embodiment and are sectional views taken along line AA of FIG. 1 (a) and line B-B of FIG. 1 (b), respectively, and (c) shows the chair of the embodiment. It is sectional drawing along the said AA line | wire which shows the base part in the state which inclined forward and inclined, and a front part and a back part are located in a front swing restriction position.

4 is an exploded perspective view showing the configuration of the chair of the embodiment.

5 (a), 5 (b) and 5 (c) are a plan view, a front view and a side view showing the stopper structure of the chair of the embodiment.

6 (a) and 6 (b) show the chair of the above embodiment in a state where the base is horizontally positioned and the front and rear portions are located at the rear swing limit position and the front swing limit position, respectively, and FIG. 1 It is sectional drawing along the AA line of (a).

It is sectional drawing which shows the chair of the said Example in use.

8 is a cross-sectional view showing the chair of the embodiment in a stored state.

Fig. 9 is an explanatory diagram showing the movement of the seating portion by the non-parallel section 4 link formed by the front and rear corner portions of the chair of the embodiment in relation to the desk.

It is explanatory drawing which shows the state which a person is seated in the chair of the said Example, and the state in which a person is not seated.

It is explanatory drawing which shows the situation where a person passes the back of the seating part of the chair of the said Example in the storage state in which a person is not seated.

It is explanatory drawing which shows the situation where a person passes the back of the seating part of the chair of the said embodiment of the intermediate state in which a person is seated.

13 (a) to 13 (e) are perspective views each showing a modified example of the embodiment.

(Explanation of symbols for the main parts of the drawing)

1: base 1a, 2d: plate

1b, 2e: Rib 2: Seat

2a: Backrest 2b: Seat

2c: Brackets 3, 5, 6, 8, 10: Shaft

4: front part 4a: bottom part

4b: top part 4c: between gaps

4d, 4e: Bolt hole 7: Rear corner part

7a: Lower part 9a: Each part

9b: top plate 11: stopper structure

11b: Upper stopper 11c: Lower stopper

B: Bolt F: Floor

R: C ring

An object of the present invention is to provide a rocking-receiving chair which advantageously solves the above-mentioned problems, and the rocking-receiving chair of the present invention includes a base fixed to a floor or a desk, and a backrest integrally coupled with each other. A seating portion having a seat, a front end portion coupled to the base portion so as to swing forward and backward, and a front side portion coupled to the seating portion so as to swing back and forth in the seating portion; The rear end portion is connected to the seating portion so as to be swingable forward and backward, and the swing axis of the upper and lower ends thereof is located behind the swing axis of the upper and lower ends of the front leg portion, the base portion of the front leg portion and the rear leg portion, and the The front and back parts and the back side are provided with a swing control unit for regulating the swing of the seating unit to a certain range. In addition, the non-parallel four-section link is formed by making the distance between the swing axes between the lower ends of the front and rear legs shorter than the distance between the swing axes between the upper ends of the front and rear legs, and forming a non-parallel 4 link. The seat and the backrest in the posture limiting position in which the seat and the backrest are in a use posture, while the seating portion and the backrest are inclined forward in the forward swing limit position regulated by the rocking restriction part. The fluctuation limiting portion is arranged so as to restrict the rear fluctuation position of the front leg portion and the rear leg portion in response to a state in which the base is inclined forward.

In such swing-back chairs, the front and rear corners are nonparallel by making the distance between the swing axes between the lower ends of the front and rear corners shorter than the distance between the swing axes between the front and rear corners. The section link is made to swing forward and backward, and the seating part is placed at the rear swing limit position regulated by the swing restricting section so that the seat and the back are in a use posture, while the front swing limit position regulated by the swing restricting section is established. The seating part is placed so that its seat and backrest are inclined forward. Then, the swing restricting section regulates the rear swing limit positions of the front leg and the rear leg in response to the inclined state of the base.

Therefore, according to the swingable retractable chair of the present invention, even when the base is fixed to the floor or the desk in an inclined state inclined forward to correspond to the inclination of the floor, in the state where the front and rear parts are located at the rear swing restriction position, The seat and the backrest integrally joined to each other of the seating part are in a posture where the backrest is inclined slightly rearward and the seat is generally horizontal, so that a person can be seated at the seating part, while the front and rear parts are Is in the front swing restriction position, the seat and the backrest of the seating portion are inclined forward, so that at least the seating portion of the seating portion can be stored in the lower portion of the upper plate of the desk.

Furthermore, according to the swing-back chair of the present invention, the backrest of the seating part is also inclined forward in a state where the front and rear corners are located at the front swing restriction position, so that a person tries to pass the rear of the chair. Even if the height of the back of the seat and the upper part of the back of the seating part generally coincide with each other, the back of the seating part obstructs the passage of a person, even though the upper part of the back of the seat does not correspond to the part of the waist. It is very advantageous when a person needs to pass the back of the chair quickly, especially during an emergency evacuation or during a lecture, while leaving the chair. Do.

Moreover, in this invention, the said back rocking restriction position is changed so that the said rocking | fluctuation control part can respond selectively to the state in which the said base was inclined forward, and the base was inclined horizontally. You may do it. According to such a structure, the same chair can be shared also on the horizontal floor and the inclined floor by changing a rear rocking restriction position, and the convenience of a rocking-type chair can be improved.

Further, in the present invention, a position in which the backrest of the seating portion stands upright at an intermediate swing position between the rear swing limit position and the front swing limit position regulated by the swing restricting portion is provided. It may be arrange | positioned as much as possible. According to such a structure, even if a seat part is moved forward while a person is seated, since a backrest becomes an upright position, a person can pass the back of the chair comparatively easily.

Furthermore, in the present invention, at least one of the front side leg portion and the rear side leg portion has a cross-sectional shape o, and the front side leg portion and the rear side leg portion may be fitted to each other at the opening portion. According to such a structure, a gap cannot be formed between the front and rear parts, and therefore, even if the distance between those parts changes due to the fluctuation of the front and back parts, the object can be prevented from being caught between those parts.

And in this invention, you may provide the said front side part and the said back side part one by one. According to such a structure, a rocking | swing retractable chair can be comprised simply and easily.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail based on drawing based on an Example. Here, Figure 1 (a) and (b) is an embodiment of the swingable retractable chair of the present invention with the base tilted forward and inclined while the front and rear corners are located in the rear swing limit position. It is a front view and a side view which show, and FIG.2 (a) and (b) are the top view and bottom view which show the chair of the Example in the state like FIG. 3 (a) and 3 (b) show the chair of the embodiment, and are sectional views taken along line AA of FIG. 1 (a) and line BB of FIG. 1 (b), respectively, and FIG. It is sectional drawing along the AA line which shows a chair in the state in which the base part inclined forward and inclined, and a front part and a back part are located in a front swing restriction position. Fig. 4 is an exploded perspective view showing the configuration of the chair of the embodiment, and Figs. 5 (a), (b) and (c) are a plan view, a front view and a side view showing the stopper structure of the chair of the embodiment.

As shown in each of the above figures, the swinging chair of the present embodiment includes a base 1 fixed to a floor (not shown) by a bolt (B, see FIG. 4) or the like, for example, plywood or fiber reinforcement. It has the backrest 2a and the sheet 2b formed integrally with each other by molding of plastic, blow molding of plastic, injection molding of plastic, etc., and bolts (B, FIG. 4) on the back of the sheet 2b. The seating part 2 which has the fixed bracket 2c is provided, The base part 1 and the bracket 2c are each plate-shaped part 1a, for example, by press working of a steel plate, casting of an aluminum alloy, etc., respectively. 2d), it is formed so that it may have two ribs 1b and 2e which protrude from the plate-shaped parts 1a and 2d and extend in parallel with each other.

In addition, the swinging chair of the present embodiment is connected to the lower end portion 4a in a forward and backward direction via the shaft 3 to the two ribs 1b of the base 1, and the seating portion 2 is connected. The front side part 4 which connected the upper end part 4b so that back-and-forth direction rotation was possible to the two ribs 2e of the bracket 2c of the via via the shaft 5, and the two ribs of the said base 1 1b) is connected to the lower end portion 7a so as to be able to swing forward and backward through the shaft 6 and the shaft 8 is interposed between the two ribs 2e of the bracket 2c of the seating portion 2. The upper end portion 7b is connected to the front and rear direction swing so that the rear end portion 7 is located behind the front side portion 4. The front side leg part 4 of those front side leg part 4 and the rear leg part 7 has a cross section which has the clearance gap 4c extending in the longitudinal direction of the said leg part in the width direction center part of the part which faces the rear leg part 7, and exists. This substantially C-shape is formed, and the rear leg portion 7 is loosely fitted to the front leg portion 4 with the cross section forming a co-shape and the co-shaped opening facing the front leg 4. 3 (b) and FIG. 4).

And here, the center axis of the shaft 6 which becomes the oscillation axis of the rear part 7 with respect to the base 1 is the center of the shaft 3 which becomes the oscillation axis of the front side part 4 with respect to the base 1. The center axis of the shaft 8 which is located behind the axis and which is the swing axis of the rear corner portion 7 with respect to the bracket 2c is the shaft 5 which is the swing axis of the front corner portion 4 with respect to the bracket 2c. ) Is located behind the central axis. The shafts 3, 5, 6, and 8 are not pulled out with respect to the ribs 1b and 2e by, for example, a C ring (see R, Fig. 4).

Moreover, in the swinging retractable chair of this embodiment, the distance between the center axis of the shaft 3 and the shaft 6 which is equal to the distance between the swinging axes between the lower end portions 4a, 7a of the front leg 4 and the rear leg 7 (A) Shorter than the distance between the center axes of the same shaft (5) and the shaft (8) to the distance between the swing axes of the front end portions (4) and the upper end portions (4b, 7b) of the rear angle portions (7), (4) and the rear corner portion 7 constitute a non-parallel section 4 link. Further, the distance between the center axes of the shafts 5 and 3 corresponding to the distance between the swing axes of the upper and lower ends 4b and 4a of the front leg 4 and the upper and lower ends 7b and 7a of the rear leg 7 are shown. While the distance between the center axes of the shafts 8 and 6 corresponding to the distances between the swing axes becomes substantially the same, the support height of the shaft 3 in the rib 1b of the base 1 is the support height of the shaft 6. It is supposed to be lower.

In addition, in the swing-type chair of this embodiment, as shown in FIG. 4, the shaft 10 is fitted in the upper part of the rear corner part 7, and is fixed by C-rings, for example. 3 and 5, the front and rear leg portions 4 and the rear leg portions 7 regulate fluctuations of the base 1 and the seating portion 2 to the bracket 2c in a predetermined range. A stopper structure 11 as a swing control unit is provided. This stopper structure 11 is slightly shifted up and down to a portion facing the rear corner portion 7 above the front corner portion 4, and a pair of bolt holes 4d and 4e each formed in two pairs (in the drawing). The bolt holes 4d of the upper jaw are fixed with four bolts B selectively, and the stopper structure 11 is formed of a rubber-like image firmly supported through the chamfered brackets 11a, respectively. It has an upper stopper 11b and a lower stopper 11c.

In the state where the stopper structure 11 is bolted to the bolt hole 4d of the upper jaw as shown in Fig. 5 (a), as shown in Fig. 3 (a), the base 1 has an angle θ. (Approximately 5 ° in the drawing) in the inclined state inclined forward, when the front part 4 and the rear part 7 are rocked with respect to the base 1 and the bracket 2c so that the seating part 2 retreats. The shaft 10 provided in the rear corner portion 7 abuts on the upper stopper 11b protruding backward from the front corner portion 4 through the gap 4c of the front corner portion 4. In addition, the stopper 11b is inclined to the back 2a of the seating part 2 very little backwards, and the seating part 2 takes the use posture in which the seat 2b is substantially horizontal. ) And the front leg portion 4 and the rear leg portion 7 to restrict the rear swing restriction position of the rear leg portion 7 and to move the seating portion 2 forward as shown in FIG. ) And the bracket 2c, the shaft 10 also abuts the lower stopper 11c protruding rearward from the front side leg portion 4 through the gap 4c, and the lower stopper 11c. Regulates the front swing limit positions of the front leg 4 and the rear leg 7 so that the seating part 2 takes a storage posture in which the backrest 2a of the seating part 2 and the seat 2b are inclined forward. do.

On the other hand, in a state where the stopper structure 11 is bolted to the bolt hole 4e of the lower jaw, as shown in Fig. 6 (a), the seating portion 2 in the state where the base 1 is horizontal. When the front leg 4 and the rear leg 7 are rocked with respect to the base 1 and the bracket 2c so that the retreat moves, the shaft 10 abuts against the upper stopper 11b. In addition, the stopper llb has the front part 4 so that the seating part 2 takes a use posture in which the backrest 2a of the seating part 2 is slightly inclined backwards and the seat 2b is substantially horizontal. And the front leg portion 4 and the rear leg portion 7 so as to regulate the rear swing restriction position of the rear leg portion 7 and move the seating portion 2 forward as shown in FIG. 6 (b). And the shaft 10 abuts against the lower stopper 11c, and the lower stopper 11c moves forward with the backrest 2a of the seating part 2 and the seat 2b forward. The front swing limit position of the front leg part 4 and the rear leg part 7 is regulated so that the seating part 2 may take inclined storage posture.

Therefore, as shown in Fig. 7, in the state where the base 1 of the chair of the present embodiment is fixed to the inclined floor surface F inclined forward, the stopper structure 11 is bolted to the upper jaw bolt hole 4d. And the front stopper 4 and the rear stopper 7 are rocked with respect to the base 1 and the bracket 2c so that the seating part 2 is spaced apart rearward from the desk 9 by the upper stopper 11b. Restricts the rear swing limit positions of the front leg 4 and the rear leg 7 so that the seating portion 2 takes the use posture. 8, in the state which fixed the base 1 of the chair of this embodiment to the surface F of the inclined floor inclined forward, the stopper structure 11 is attached to the bolt hole 4e of a lower jaw. ), The front stopper 4 and the rear stopper 7 swing relative to the base 1 and the bracket 2c so that the seating part 2 approaches the desk. The front swing limit position of the front leg part 4 and the rear leg part 7 is regulated so that 2) may take the said storage position.

FIG. 9 is an explanatory diagram showing the movement of the seating portion 2 due to the non-parallel four-section link formed by the front leg 4 and the rear leg 7 in relation to the desk 9. In addition, the desk 9 in the example of illustration has the leg 9a by which the lower end was fixed to the floor F to which the base 1 was fixed, and the top board fixed to the upper end of the leg 9a. 9b)

According to the swinging-type chair of this embodiment, even when the base 1 of the chair of the present embodiment is fixed to the surface F of the inclined floor inclined forward, as shown on the left side in FIG. In the state where 4) and the rear corner portion 7 are located at the rear swing limit position, the seat 2b and the backrest 2a which are integrally engaged with each other of the seating portion 2 are in the above-described use posture, and the person H ) Can be seated on the seating part 2, while the front part 4 and the rear part 7 are located at the front swing restriction position as shown on the right side in FIG. 10. The seat 2b of 2) and the backrest 2a are inclined forward, and the seat 2b of the seating part 2 can be accommodated below the upper plate 9b of the desk 9.

In addition, according to the swinging chair according to the present embodiment, as shown in FIG. 11, the backrest 2a of the seating part 2 is in a state in which the front leg 4 and the rear leg 7 are located at the front swing limit position. ) Is also inclined forward, so when the person H tries to pass through the back of the chair, the part of the waist, which is a relatively wide part of the person H, and the back 2a of the seating part 2 Even if the heights of the upper end portions of the upper back portions coincide with each other, since the upper end portions of the backrests 2a do not correspond to the lower back portions, the backrests 2a of the seating portion 2 are obstructed by the passage of the person H. The person H can pass the back of the chair which was stored very easily. This is particularly advantageous when a person needs to pass through the back of the chair quickly, such as during an emergency evacuation or during class leave.

In addition, according to the swinging retractable chair of the present embodiment, as shown in FIG. 12, the front leg 4 and the rear leg 7 are seated at an intermediate rocking position between the rear rocking limit position and the front rocking limit position. Since the back 2 is arranged so that the back 2a is substantially upright, even when the seat 2 is moved forward with the person H seated, the back 2a is generally upright. Since it is a posture, the other person H can pass the back of the chair relatively easily, and at that time, the seat 2b integrally formed with the backrest 2a is only slightly inclined forward. However, even the seated person (H) does not have to be very uncomfortable.

In addition, according to the swinging-type chair of the present embodiment, the front leg 4 and the rear leg 7 are fitted together as shown in Fig. 3 (b), so that the front and rear leg portions 4 and 7 are separated. Since a gap cannot be formed in the upper and lower parts, even if the intervals of the respective parts 4 and 7 are changed by the fluctuations of the front and back parts 4 and 7 between the rear swing limit position and the front swing limit position, such angles The object can be prevented from being pinched between (4, 7).

In addition, according to the swinging chair according to the present embodiment, since only one front leg 4 and one rear leg 7 are provided, the swinging chair can be configured simply and easily.

13 (a) to 13 (e) show a modified example of the above embodiment, and in FIG. 13 (a), the pipe member so that the front leg 4 and the rear leg 7 each have an I-shape. Is formed in combination with each other, and in FIG. 13B, the front side leg portions 4 and the rear side leg portions 7 are each formed in a thick plate shape. In addition, in FIG.13 (c), while the back corner part 7 is formed in a square cylinder shape, the front side corner part 4 is formed in a thick plate shape, and the front corner part 4 is a square cylinder shape rear part 7 ) Is housed inside. In FIG. 13D, the front leg 4 and the rear leg 7 are each bent to form a pipe member in a U-shape. In FIG. 13E, the rear corner portion 7 is formed in a cross-sectional shape, and the front corner portion 4 is formed in a cylindrical shape, and the front corner portion 4 is an opening portion having a shape of the corner portion of the rear corner portion 7. It is loosely fitted and is located inside the rear corner 7.

As mentioned above, although demonstrated based on the example of illustration, this invention is not limited to the above-mentioned example, For example, the front side as a rocking | fluctuation control part which regulates the fluctuation | variation with respect to the base part and the seating part to a certain range, for example. A stopper member such as a stopper structure which the member fixed to each part contacts by the front and rear corner parts may be provided in the rear corner part, or a stopper member in contact with at least one of the front and rear corner parts, such as a base or a seating part, may be provided. Also good.

In addition, in the swing-back chair of the present invention, at least one of the front and rear corners may be two or more, and the distance between the swing axes of the upper and lower ends of the front corners is less than the distance between the swing axes of the upper and lower ends. At the same time, the rocking axes of the lower end portions of the front and rear portions with respect to the base may be arranged at the same height. Further, the base may be fixed to any part of the desk, for example, each part, or the like, and the seat back and the seat of the seat may be formed separately and may be integrally joined by an iron or the like.

And the swinging-type chair of this invention is a biasing means, such as a spring which oscillates a front part or a back part so that at least the seat of a seating part may be accommodated in the lower part of the upper board of a desk in a free state in which a person is not seated, and will be in a storage state. You may have more. The swinging chair of the present invention is not limited to a school chair, but can also be applied to, for example, a chair for a meetinghouse, a conference room, or a conference hall.

Claims (5)

With base set on the floor or desk, A seating part having a backrest and a seat integrally coupled to each other, A front end part connected to the base so as to swing back and forth in a forward direction, and a front side part connected to the seating part so as to swing back and forth in a forward direction; The lower end portion is coupled to the base so as to swing back and forth, and the rear end portion is coupled to the seating portion so as to swing back and forth, and the swing axis of the upper and lower ends thereof is located behind the swing axis of the upper and lower ends of the front leg portion. Wow, And a rocking restraint for regulating the swinging of the base portion and the seating portion to a predetermined range in the front leg portion and the rear leg portion, The non-parallel four-section link is formed by shortening the distance between the pivot axes of the front and rear portions of the front and rear portions to be smaller than the distance between the pivot axes of the front and rear portions. The seat and the backrest are arranged at the rear swing restriction position regulated by the swing restriction section so that the seat and the backrest are in a use posture, while the seat and backrest are secured at the front swing restriction position regulated by the swing restriction section. Place it in an inclined forward position, And the swing restraint section regulates the rear swing limit position of the front leg and the rear leg in response to a state in which the base is inclined forward. The method of claim 1, The oscillation regulating unit changes the rear oscillation limiting position of the front leg portion and the rear leg portion so that the base can be selectively responded to the state in which the base is inclined forward and the base is horizontal. Retractable chair. The method according to claim 1 or 2, The front leg and the rear leg are arranged so that the seat back is in an upright position at an intermediate swing position between the rear swing restriction position and the front swing restriction position regulated by the swing restriction portion. Swingable retractable chair. The method according to any one of claims 1 to 3, At least one of the front leg portion and the rear leg portion has a cross-sectional shape, and the front leg portion and the rear leg portion are fitted to each other at an opening thereof. The method according to any one of claims 1 to 4, A swinging retractable chair having the front and rear corner portions one by one.