EP0312916A1

EP0312916A1 - Ring binder mechanism

Info

Publication number: EP0312916A1
Application number: EP88117060A
Authority: EP
Inventors: Dennis William Gateshead
Original assignee: Bensons International Systems Ltd
Current assignee: Bensons International Systems Ltd
Priority date: 1987-10-21
Filing date: 1988-10-13
Publication date: 1989-04-26
Also published as: GB8824700D0; DK584088A; GB8724672D0; GB2211145A; DK584088D0

Abstract

A ring binder mechanism comprises a base member (10) with two or more rings (20,22) mounted thereon at spaced positions along the length thereof. In conventional manner, each ring comprises two separable ring segments which are formed into two opposing sets disposed on opposite lateral sides of the centerline of a base member, each set of ring segments being mounted on a respective one of a pair of blades (19, 19a) which are hingedly connected together along the centerline of the base member and at their outer edges engage the lateral margins (14a, 15a) of a front plate (11) which serves as a spring means whereby the blades are driven towards either of two extreme angular positions whereby the sets of ring segments are held either in the open or closed positions. The front plate (11), instead of being of smoothly arched shape as is conventional, is of shallow V-shape in transverse section and presents two flat faces (14, 15) which conform as closely as possible to the apex formed by the blades when the ring segments are in their open position.

Description

This invention relates to ring binder mechanisms of the kind comprising a longitudinal base member and two or more rings mounted thereon at spaced positions along the length thereof, each ring comprising two, separable ring segments, the segments being formed into two opposing sets which are disposed on opposite lateral sides of the centreline of the base member and mounted thereon for movement between respective open and closed positions. The base member comprises a front plate and a pair of blades hingedly connected together along the centreline of the base member with each of said blades carrying one of said sets of ring segments. The blades act as an over-centre device and engage the front plate at their outermost edges, and the front plate serves as a spring means whereby the blades are driven towards either of two extreme angular positions whereby the sets of ring segments are held in either the open or closed positions.
Conventionally, in such ring binder mechanisms, the front plate is of smoothly arched shape in transverse section in order to accommodate the apex formed by the blades when the ring segments are in the open position. However, such arched shape has two particular disadvantages.
Firstly, it requires the use of a wider strip of material than would be the case if it were possible to adopt a flatter shape, although the front plate cannot be made completely flat if it is to accommodate the blades in practice. Secondly, the force exerted on the blades to retain them in the two extreme positions is directly related to the superficial width of the front plate, i.e. the width thereof measured over the curved surface.
In accordance with the invention, we make the front plate of shallow V-shape in transverse section, instead of smoothly arched shape, so as to conform as closely as possible to the apex formed by the blades when the ring segments are in the open position. This apparently simple modification firstly effects a small but advantageous saving of material in the manufacture of the front plate due to the reduced superficial width thereof over two flat inclined faces as compared an arc passing through the apex point. Secondly, it makes it possible to use thinner material for the front plate, thereby effecting a further saving of material, since the reduced superficial width of the front plate provides a stronger spring characteristic for any given thickness of material, and the same characteristic as presented by a front plate of arched shape can be achieved with thinner material when the front plate is of V-shape as in accordance with the invention.
The invention will now be described by way of example, with reference to the accompanying drawings wherein:-

FIGURE 1 is a perspective view of one embodiment of ring binder mechanism;
FIGURE 2 is a transverse section through said mechanism, with the ring segments closed; and
FIGURE 3 is a transverse section through said mechanism with the ring segments open.

The mechanism illustrated comprises a base member 10 which includes a front plate 11 formed as a metal pressing with fixing holes 12 at opposed ends and slots 13 for the passage of ring segments as hereinafter described. As can be seen, the front plate 11 is formed over the majority of its area as two flat faces 14, 15 meeting at an apex 16 on the longitudinal centreline, although end portions of the apex are formed with flats 17, and defines a cavity 18 which is open at the underside. The flats assist in the location of the base in an automatic rivetting machine when the mechanism is secured to a binder in conventional manner.
The cavity 18 defined by the front plate 11 houses a pair of blades 19, 19a which are hingedly connected together at their contiguous edges on the centreline of the base, the blades being located at their outermost edges in grooves formed by inturned margins 14a, 15a of the front plate.
Two rings 20, 22 are formed from respective ring segments 21, 21a, 23, 23a, the segments 21 and 23 being carried by blade 19 and the segments 21a, 23a being carried by the blade 19a so as to form two separable sets.
As can be seen from Figure 2, when the segments are closed, the contiguous edges of the blades 19, 19a are displaced downwardly relative to the outermost edges, but still within the cavity defined by the front plate 11.
To move the segments to the open position shown in Figure 3, the contiguous edges of the blades require to be moved upwardly through a dead-centre position in which the blades are co-planar, to a position in which the contiguous edges are displaced upwardly relative to the outermost edges of the blades. During such movement, the front plate 11 is stretched resiliently by outward movement of the lateral margins 14a, 15a by a small amount in order to accommodate the co-planar relationship of the blades 19, 19a. Such resilient stretching of the front plate 11 provides the spring force which is required to drive the blades positively to either of the extreme positions as illustrated, and therefore to maintain the ring segments in either the open or closed position as required.
As can be seen from Figure 3, the sectional shape of the front plate 11 corresponds as closely as possible to the apex formed by the blades 19, 19a when the ring segments are in the open position. Accordingly, the superficial width of the front plate 11 is reduced to a practical minimum and in consequence the material of which the front plate 11 is made can be of correspondingly reduced thickness without weakening the spring effect for the reasons mentioned above.
It will be appreciated that any number of rings may be carried by the blades, and that the base member may include any known type of trigger to act directly on the blades for the opening and closing movements of the ring segments.

Claims

1. A ring binder mechanism of the kind comprising a longitudinal base member (10) and two or more rings (20,22) mounted thereon at spaced positions along the length thereof, each ring comprising two, separable ring segments (21,21a; 23,23a), the segments being formed into two opposing sets which are disposed on opposite lateral sides of the centreline of the base member and mounted thereon for movement between respective open and closed positions, the base member comprising a front plate (11) and a pair of blades (19,19a) hingedly connected together along the centreline of the base member with each of said blades carrying one of said sets (21,23; 21a,23a) of ring segments, and the blades acting as an over-centre device and engaging the front plate (11) at their outermost edges, the front plate thereby serving as a spring means whereby the blades are driven towards either of two extreme angular positions and whereby the sets of ring segments are held in either the open or closed positions, characterised in that the front plate (11) is of shallow V-shape in transverse section so as to conform as closely as possible to the apex formed by the blades (19,19a) when the ring segments (21,21a; 23,23a) are in the open position.

2. A ring binder mechanism according to Claim 1 wherein the front plate (11) is formed with two flat faces (14,15) meeting at an apex (16) on the longitudinal centreline of the base (10).

3. A ring binder mechanism according to Claim 2 wherein end portions of the apex (16) of the front plate (11) are formed with flats (17).

4. A ring binder mechanism according to any one of the preceding claims wherein the blades (19, 19a) engage at their outermost edges in grooves formed by inturned marginal portions (14a, 15a) of a front plate (11).

5. A ring binder mechanism substantially hereinbefore described with reference to the accompanying drawings.

6. A front plate for a ring binder mechanism as claimed in Claim 1 and having over the majority of the length a cross-sectional shape substantially as hereinbefore described with reference to and as shown in Figures 2 and 3 of the accompanying drawings.