JPH0374088B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a tilting device for a backrest of a chair used for office use.

Prior Art and its Problems As a chair that can be converted into a working mode and a breathing mode by tilting the backrest back and forth, for example, as shown in FIG. A device in which the backrest 2 is biased toward the forward rotation side using a spring (not shown) or the like is commonly used.

However, in the case of such a chair, when the user 3 tilts the backrest 2 backward from the working posture to take a resting posture, the contact point P between the user's back and the backrest 2 is on the backrest 2 side. It moves in an arc around the pivot point O1 and reaches the P1 position, whereas on the user 3 side it moves in an arc around the waist thrust part O2.
The P2 position is much lower than P1. Therefore, there was a problem that a misalignment occurred between the back of the user 3 and the surface of the backrest 2, and the user's 3's shirt etc. would ride up and gradually protrude due to repeated tilting. In addition, in the resting mode, the lower back of the user 3 is moved away from the backrest compared to the working mode, so the angle at which the user's back hits the backrest 2 becomes worse, making it difficult to properly transfer the weight of the upper body to the backrest 2, resulting in a heavy burden on the lower back. I couldn't say I could take a comfortable position.

Means for Solving the Problems This invention has been made to solve the above-mentioned conventional problems, and by moving the backrest forward and tilting backwards, the backrest of the user is adjusted when changing to the resting position. To provide a chair backrest tilting device which does not cause any deviation from the backrest and can provide an ideal comfortable posture for human engineering.

That is, in order to achieve the above object, the backrest tilting device according to the present invention has attachment arms 11a, 11 extending forward on both left and right sides of the lower part of the back frame 11.
a is formed, and two front and rear links 16 and 17 are pivotally connected at the upper end to each mounting arm 11a, and the lower ends of each link 16 and 17 are pivotally connected to a receiving frame 12 supported by the leg body 13. , these links 16,
The upper end pivot portion 16a of the front link 16 at the rear rotation limit is provided with a stopper portion 18 that determines the rear rotation limit of the front link 17, and a spring member 20 that constantly biases these links 16 and 17 toward the rear rotation side. is located behind the lower end pivot portion 16b, and the upper end pivot portion 17a of the rear link 17 is positioned directly above or in front of the lower end pivot portion 17b, thereby pressing the back frame 11 rearward. The back frame 11
It is constructed so that it moves forward and tilts backward.

Embodiments Hereinafter, the present invention will be explained based on illustrated embodiments.

In FIGS. 1 to 6, reference numeral 11 denotes a back frame to which the backrest 10 is attached, and mounting arms 11 having a downwardly open U-shaped cross section extend forward on both left and right sides of the lower part.
a and 11a are integrally formed.

Reference numeral 12 indicates a substantially box-shaped receiving frame with an open upper surface and an arc-shaped rear part; 13 indicates a leg body consisting of a pair of left and right substantially inverted V-shaped frames;
3 has a U-shaped frame portion 13a that is open inward.
is formed, and the receiving frame 12 is fixed to the leg body 13 by fitting its both sides into the U-shaped frame part 13a and screwing screws 14, 14, . . . from the outer surface side and the lower surface side. ing. 15 is a seat plate disposed on the receiving frame 12.

Each mounting arm 11a of the back frame 11 has an L-shaped front link 16 concave toward the front side and a straight rear link 17, which are connected at the upper ends via pivot pins 16a and 17a, respectively. It is pivoted so that it can rotate forward and backward in a vertical plane. Also, both links 16,1
The lower ends of 7 are the side wall portions 1 of the receiving frame 12, respectively.
It is pivotally attached to the lower part of the frame 2a via pivot pins 16a and 17b so as to be rotatable in the front and back directions within a vertical plane, whereby the back frame 11 is supported on the receiving frame 12 so as to be swingable back and forth. There is.

Thus, the lower half of the front link 16 forms a stopper part 18 that abuts the inner bottom surface of the receiving frame 12 on the rear side to define the rearward rotation limit of the front link 16. At the operating position of the stopper portion 18, that is, at the rearward rotation limit position of the front link 16, the upper end side pivot pin 16 of the front link 16
a is located behind the lower end side pivot pin 16b, and the upper end side pivot pin 17a of the rear link 17 is located slightly forward of the lower end side pivot pin 17b. That is, both links 16,
The vertical pivot joints 17 are arranged at the apex of a trapezoid.

Further, on the front part of the inner bottom surface of the receiving frame 12, a plurality of protrusions 19, 19, which face each other in the front and rear, are protruded at predetermined intervals along the left-right direction, and each pair of protrusions 19, 19 A bar spring 20 is fitted so as to be rotatable in the circumferential direction, and is held by a stop plate 19a screwed onto both projections 19, 19 with screws 19b so as not to be removed. This rod spring 20 comes into contact with a spring adjustment bolt 21 screwed into a screw hole 21a of the front wall 12b of the receiving frame 12 at an inverted U-shaped part 20a formed at the center, and at both ends. The curved L-shaped portions 20b, 20b constantly press the front surfaces of the bent portions of the front links 16, 16 on both sides by the torsional restoring force. Due to this pressure, the front link 16 is urged toward the rearward rotation side.
Normally, the stopper part 18 is held at a position where it contacts the inner bottom surface of the receiving frame 12, and the back frame 11
maintains the forward leaning limit position, that is, the working form.

Incidentally, the side wall portion 12a of the receiving frame 12 is provided with an arc-shaped elongated hole 12d into which the end of the L-shaped portion 20b of the bar spring 20 is fitted to restrict the rotation range. Notches 12e are provided on both sides, through which the mounting arms 11a of the back frame 11 are inserted.
is provided.

On the other hand, the receiving frame 12 is provided with a rail receiving piece 22a projecting forward from the upper edge of the front wall portion 12b and a rail mounting protrusion 22b projecting upward from the inner bottom surface near the rear on both left and right sides. A lower rail 23 having a generally upwardly open U-shaped cross section is constructed between the receiving piece 22a and the protrusion 22b, and is fixed with screws 26. Further, on both sides of the lower surface of the seat plate 15, an upper rail 24 is fixed with screws 26 and has a substantially downwardly open U-shaped cross section and has inward claw portions 24a formed on the lower edges of both sides. However, both rails 2
3 and 24 are grooves 23a and 23 provided on both sides of the lower rail 23 to connect both claws 24a of the upper rail 24.
a, so that the seat plate 15 is attached to the receiving frame 12 so as to be movable back and forth, and the spring retaining pin 25a on the lower surface and the front wall of the receiving frame 12 It is pulled and biased rearward by a pair of left and right coil springs 25, 25 that are engaged between a locking hole 25b formed in the portion 12b. The range of movement of the seat plate 15 back and forth is determined by a stopper piece 23b formed upright at the rear end of the lower rail 23 at the rear, and a stopper pin (not shown) screwed into the intermediate portion from below at the front. On the other hand, each is regulated at a position where the rear end of the upper rail 24 abuts, and is normally set to about 70 mm.

In the chair with the above configuration, when the user is in a working posture that does not press the back frame 11,
As shown by solid lines in FIGS. 1 and 2, the stopper portion 18 of the front link 16 comes into contact with the inner bottom surface of the receiving frame 12 due to the biasing force of the bar spring 20, and the back frame 1
1 is held at the forward tilt limit position.

Therefore, when the user applies a backward pushing force to the backrest 10 with his or her back in order to take a resting posture, both the front link 16 and the rear link 17 tilt forward, as shown by the imaginary lines in FIGS. and front link 16
The position of the upper end side pivot pin 16a becomes higher, and the position of the upper end side pivot pin 17a of the rear link 17 becomes lower, and accordingly, the front end side of the mounting arm 11a of the back frame 11 is lifted and the back frame 11 is moved backward. By lowering the end side, it tilts backward, and moves forward as a whole by the amount of forward tilt of both links 16 and 17. This amount of movement is set to about 25 mm, for example, when the backward tilt angle is about 15 degrees with respect to the working style.

Therefore, the backrest 10 sinks and tilts backwards, so that the contact surface between the user's back and the backrest 10 does not shift during the transition from the work mode to the rest mode, and the shirt etc. does not slide up. is avoided. Moreover, due to the forward movement of the back frame 11, there is almost no change in the positional relationship between the user's back and lumbar region and the backrest 10 between the work mode and the rest mode, and the contact between the user's back and the backrest 10 in the work mode is Since the angle is carried over to the resting form, the most ideal ergonomically comfortable posture with less strain on the lower back is achieved.

Note that the return from the rest mode to the work mode is automatically performed by the torsional force stored in the bar spring 20.
The spring strength of the bar spring 20 can be arbitrarily set by adjusting the degree of threading of the spring adjustment bolt 21.

In addition, in the case of the chair configured as described above, the seat plate 15 can be moved back and forth independently of the back frame 11, so when in the rest mode, the seat plate 15 can be moved forward to take a posture of stretching the lower back, or can be reciprocated back and forth. It is possible to bend and stretch the lower back by exercising, and the sitting position can be changed back and forth as necessary even in the office mode.

In addition, in this invention, the front link 16 is made straight like the rear link 17, and both links 16,
A stopper portion for determining the rearward rotation limit of 17 may be provided on the receiving frame 12 side instead of on the front link 16 itself. In addition, as a means for biasing both links 16 and 17 toward the rearward rotation side, in addition to the pressing by the rod spring 20, the means for urging both links 16 and 17 or the mounting arm portion 11a of the back frame 11 and the receiving frame 1
It is also possible to adopt a method of hooking a coil spring between the two and utilizing the tensile force of the coil spring. Furthermore, the seat plate 15 may be fixed to the receiving frame 12.

Effects of the Invention According to the chair back tilting device according to the present invention, the back frame is configured to move forward and tilt backward when a backward pressing force is applied to the backrest. It sinks down and tilts backwards, so there is no misalignment of the contact surface between the user's back and the backrest, shirts, etc. do not slide up, and the angle of contact between the back and the backrest remains the same as in the resting mode. Inherited from the previous generation, the ergonomically ideal comfortable posture with less strain on the lower back is achieved.
Furthermore, this tilting device is mechanically extremely simple, so it can be easily manufactured at low cost and has excellent operational reliability.

[Brief explanation of drawings]

Fig. 1 is a vertical side view of the entire chair according to an embodiment of the present invention, Fig. 2 is a longitudinal side view of the backrest tilting device of the chair, and Fig. 3 shows how the back frame, support frame, and legs are attached. FIG. 4 is an exploded perspective view showing how the seat plate is attached to the receiving frame. FIG. 5 is a partially cutaway plan view of the same chair. FIG. The perspective view, FIG. 7, is a schematic side view illustrating the backward tilting motion of the backrest of a chair in a conventional example. 10... Backrest, 11... Back frame, 11
a...Mounting arm, 12...Receiving frame, 13...
...Leg body, 16...Front link, 16a...Pivot pin, (upper end pivot part), 16b...Pivot pin (lower end pivot part), 17...Rear link, 17a...Pivot pin (upper end pivot portion), 17b... pivot pin (lower end pivot portion), 18... stopper portion, 20... rod spring (spring member).

Claims (1)

[Claims] 1 Attachment arms extending forward are formed on both left and right sides of the lower part of the back frame, and two front and rear links are pivotally attached to each attachment arm at the upper end, and the lower ends of each link are supported by the legs. The upper end of the front link is pivoted at the rear rotation limit, and includes a stopper part that is pivotally attached to the receiving frame and determines the rear rotation limit of these links, and a spring member that constantly biases these links toward the rear rotation side. The upper end of the rear link is located behind the lower end pivoting part, and the upper end of the rear link is located directly above or in front of the lower end pivoting part, so that when the back frame is pressed rearward, the back A chair backrest tilting device configured such that a frame moves forward and tilts backward.