Improvements relating to obstetric chairs

Abstract

  An obstetric chair comprising a chair proper (10) carried by a support comprising a base frame (15) supported on braked castor wheels (16) and including two triangulated linkages of which the first comprises legs (17, 18) pivotally connected about horizontal axes (20, 21) to the base frame (15) with the former axis also capable of horizontal translatory movement lengthwise of the frame, and a second triangulated linkage comprising leg (17), extension thereof (17a) and tie member (24) together with a part of the back portion (12) of the chair proper. The geometry of the first linkage can be varied by a hydraulic ram (31) which raises and lowers the pivotal apex (19) and hence the chair proper and the geometry of the second linkage can be varied by adjusting the effective length of the tie member (24) which comprises cooperating screw-threaded components (24a, 24b) relatively rotatable by a handle (25).

Description

[0001] This invention relates to obstetric chairs.

[0002] One of the requirements of an obstetric chair is that it shall be capable of undergoing positional adjustment, both in relation to the height of the seat portion of the chair above the ground and in relation to the attitude of the chair, that is to say any tilt presented by the generally horizontal seat portion of the chair and generally vertical back rest portion of the chair in relation to reference horizontal and vertical planes. Such a chair is shown in GB-A-2,017,498 which discloses an obstetric chair comprising a chair proper of a form suitable for occupation by a patient preparatory to and during delivery, a chair support including a generally horizontal base, and means for controlling the height and attitude of the chair proper relatively to the base.

[0003] It is however desirable that this requirement shall be met by a structure which is simple and hence does not entail high manufacturing cost and yet is sufficiently strong to support the chair proper in a stable manner notwithstanding movement of the patient from time to time.

[0004] According to the invention the requirement is achieved by providing that the chair support comprises a first chair carrier linkage of triangulated form having legs extending downwardly from an apex and connected at their lower ends to the base in a pivotal mode about substantially horizontal axes, one of the legs having an extension projecting beyond the apex and serving as an attachment means for the chair proper at one of two vertically spaced attachment points on said chair, and tie means for connecting the chair proper at the other of said vertically spaced points to one of the legs of the first triangulated linkage so that the tie means, chair, and the last said leg form effectively a second triangulated linkage, and that the means for controlling the height and attitude of the chair comprises

(i) means for varying the geometry of the first triangulated linkage and hence the height of its apex and the first attachment point,

(ii) means for varying the geometry of the second triangulated linkage and hence the angle to the vertical of a line drawn through said points of attachment.

[0005] By provision of a support for the chair proper incorporating two triangulated linkages, the structure as a whole can be made of sufficient rigidity (as regards the position into which it is adjusted) to provide reliable and stable support for the chair proper, can nevertheless avoid the use of individual members of the triangulated structures which are of excessive cross-section and weight and can hence be produced economically.

[0006] Further features of the invention will be apparent from, or specifically pointed out in, the following description given by way of example with reference to the accompanying drawing wherein there is shown (diagrammatically) one embodiment of obstetric chair in accordance with the invention.

[0007] Referring to the drawing, the structure comprises a chair proper 10 of any suitable construction for the purpose in question and including a seat portion I I preferably incorporating an open-fronted slot, a back rest portion 12 and at each side arms 13 which serve to connect the back rest portion and seat proper and rigidify the structure as a whole.

[0008] The chair is mounted on a support 14 which comprises a base 15 conveniently in the form of a frame which is rectangular as viewed in plan and which is of elongate form, i.e. has a greater length than width.

[0009] The base frame is mobile by reason of being mounted on wheels 16 which may conveniently be castor wheels capable of swivelling about a vertical axis and of a design conventionally employed in hospital furniture. One or more of these wheels may be equipped with a brake means 16a movable between an operative braking position to hold the base frame stationary and a releasing position in which it can be moved from place to place in the hospital or maternity ward.

[0010] The support for the chair proper further comprises two triangulated structures of which the first comprises, at each side of the base frame, two legs 17 and 18 pivotally connected to each other about a horizontal axis 19 forming the apex of the triangulated structure. From this apex the legs extend downwardly and are connected at their lower ends to a side member of the base frame 15, in both cases for movement about horizontal pivotal axes 20 and 21 respectively, and in the former case for translatory movement in a direction longitudinally of the base frame.

[0011] For this purpose the lower end of the leg 17 may be equipped with roller means (not shown) which is captive laterally in a horizontally extending guide means 22 secured to one of the side members of the base frame 15.

[0012] The leg 17 has an extension 17a beyond the apex 19 and the free end of the extension 17a is adapted in any suitable manner to provide a support point 23 for the chair proper 10. For this purpose the back rest portion 12 may be provided with a horizontal rail or spindle received in an upwardly presented bearing or cradle of the extension 17a with suitable retaining means to prevent removal of the chair proper from assembled relation with the support 14.

[0013] The second triangulated structure incorporated in the support 15 comprises a tie means in the form of a tie member 24 which includes male and female components 24a, 24b formed with complementary cooperating acme threads. The female component may incorporate a nut housed in the interior of the generally tubular component 24b and rotatable by means of a suitable drive mechanism operable by means of a rotatable handle 25.

[0014] The cooperating threads are self-locking in relation to load, i.e. tension or compression applied endwise to the'tie member 24. At one end the tie member 24 is connected for pivotal movement about an axis 26 to a bracket 27 clamped or otherwise secured to the leg 17 while at its opposite end the tie member 24 is adapted for connection pivotally about an axis 28 to the back rest portion 12 of the chair proper at a second attachment point spaced vertically from the axis 23.

[0015] The connection at the point 28 may be releasable, i.e. comprise a bearing or cradle and a rod or rail together with retaining means for securing these parts releasably in assembled relation.

[0016] To adjust the height of the chair proper in an upward and downward direction, as indicated by arrow 29, the geometry of the first triangulated linkage is varied by an actuating means 30 conveniently in the form of a hydraulic ram 31, the piston rod 32 of which may be pivotly/connected to any convenient part of the first triangulated structure, foc example a bracket 18a projecting laterally from the leg 18, or possibly from the extension 17a (the precise arrangement not being shown in the drawing).

[0017] For admitting fluid, for example hydraulic fluid, to the ram and exhausting it therefrom, any suitable means may be provided such as a foot-operated or hand-operated pump 34 associated operatively with valve means (not shown).

[0018] In operation extension of the piston rod 32 serves to raise the height of the apex 19 and hence the attachment point 23, the pivotal axes 20 and 21 then moving towards each other by reason of movement of the roller means along the guideway 22.

[0019] It will be understood that the duplication of the first triangulated structure at each side of the base frame provides the necessary lateral stability for the chair proper, there being either two laterally spaced attachment points 23 or else an elongate bearing for receiving a rod or rail on the back rest portion 12 of the chair proper.

[0020] On the other hand, in respect of the second triangulated linkage, it would be adequate for a single tie member 24 to be provided in a central position between the lateral boundaries of the back rest portion 12 of the chair and connected to a rod which defines the pivotal axis 26 and extends between brackets 27 on the two laterally spaced legs 17.

Claims

1. An obstetric chair comprising a chair proper (10) of a form suitable for occupation by a patient preparatory to and during delivery, a chair support (14) including a generally horizontal base (15), means for controlling the height and attitude of the chair proper ( I 0) relatively to the base (15), characterised in that the chair support comprises a first chair carrier linkage of triangulated form having legs (17, 18) extending downwardly from an apex (19) and connected at their lower ends to the base (15) in a pivotal mode about substantially horizontal axes (20, 21), one (17) of the legs (17, 18) having an extension (17a) projecting beyond the apex (19) and serving as an attachment means for the chair proper (10) at one (23) of two vertically spaced attachment points (23, 28) on said chair (10), and tie means (24) for connecting the chair proper (10) at the other (28) of said vertically spaced points (23, 28) to one (17) of the legs (17, 18) of the first triangulated linkage so that the tie means (24), chair (10), and the last said leg (17) form effectively a second triangulated linkage, and the means for controlling the height and attitude of the chair comprises

(i) means (30) for varying the geometry of the first triangulated linkage and hence the height of its apex (19) and the one attachment point (23),

(ii) means (24a, 24b) for varying the geometry of the second triangulated linkage and hence the angle to the vertical of a line drawn through said points of attachment (23, 28).

2. An obstetric chair according to claim I wherein at least one (17) of the legs (17, 18) of the first triangulated linkage is connected at its lower end to the base (18) for movement along the base (15) in a translatory mode and the means (30) for varying the geometry of the first triangulated linkage produces variation in the distance between spaced pivotal, substantially horizontal, axes (20, 2l) about which the lower ends of the legs (17, 18) pivot relatively to the base (15).

3. An obstetric chair according to either of claims I and 2 wherein the means for varying the geometry of the second triangulated linkage comprises means (24a, 24b) for varying the effective length of one of the members (17, 24, 12) thereof.

4. An obstetric chair according to claim 3 wherein the tie means (24) of the second triangulated linkage comprises a tie member including components (24a, 24b) movable relative to each other to vary the effective length of the tie member (24) by or through the intermediary of mechanism which is self-locking under the load imposed upon it during occupancy of the chair proper.

5. An obstetric chair according to claim 4 wherein the tie member comprises screw-threaded male and female components (24a, 24b), with means (25) for rotating one of these relatively to the other.

6. An obstetric chair according to any one of the preceding claims wherein the base (15) is of elongate form as viewed in plan and the first and second triangulated linkages are arranged to present attachment means (23, 28) lying in an upwardly extending plane transverse to the length of the frame (15) and situated adjacent one end thereof to enable the chair proper (10) to be mounted at one end of the base (15) and presented outwardly thereof.

7. An obstetric chair according to any one of the preceding claims wherein the base is mounted on wheels (16) equipped with brake means ( I 6a).

Drawing