Background of the Invention

This invention relates to binders for cover folders and, -more particularly, to binders that are able to enhance the removable retention of sheets placed within an associated folder.

Cover folders are widely used with sheets of paper that form a report or presentation. The cover is a folded sheet of plastic or other material that protects interior contents. In order to retain the sheets within the cover folder, it is conventional practice to use a binder along an edge of the cover. Such binders can be formed by elongated panels joined along a common edge, with a narrow opposite opening through which the cover is inserted.

Prior art cover binders have the disadvantage that when the cover is opened and separated, even only slightly, there is a tendency to force it from the binder. Generally there is insufficient friction to keep the binder and cover together, so that an adhesive or other element is needed to secure proper engagement. Additionally when sheets of paper are inserted into the cover, and the cover opened, the sheets typically slip from the binder.

Other prior art cover folders contain fasteners which must be inserted through the cover, the binder and the contents. This necessitates the need for holes along the edge of the folder, as well as corresponding holes in the inserted sheets. Holes are undesirable since sheets tend to tear during normal handling. Fasteners also make it more difficult and time consuming for the user to insert and remove sheets.

Moreover, both fasteners and edge holes detract from the appearance of

> documents held by the cover.

Accordingly, it is an object of the invention to provide a binder which is able to securely retain a cover and its internal contents, without the need for external fasteners. A related object is to provide a binder which has enhanced tension capacity when the cover is open.

Another object of the invention is to facilitate the insertion of covers into binders and their secure retention. A related object is to achieve^ enhanced security for the retained cover and contents, in the face of greater ease of insertion. Still another related object is to provide for ease of removability of inserted sheets, as well as covers, despite their secure retention in normal condition.

Still another object of the invention is to provide a binder which can facilitate stacking, has suitable appearance and is simple to use.

Summary of the Invention In accomplishing the foregoing and related objects, the invention provides a binder formed by an elongated member with a first panel that diverges at an opening with respect to a second panel. They elongated member extends continuously from the first panel to the second panel to form an interior opening for receiving an elongated sheet. The binder can include an interior projection within the elongated member, desirably beyond the first and seond panels. The first and seond panels advantageously are demarked from the remainder of the binder by an elongated indent line which defines a demarcation between each of the panels and the remainder of the elongated member. A protuberance on the inside of one of the panels can be provided to increase the grip against any inserted material.

In accordance with one aspect of the invention, the spine of the binder is provided with a series of raised lined extensions, or ribbing to facilitate the handling of the spine, and also facilitate the insertion of the cover and contents into the spine. The raised ribbing on the spine is non-uniformly distributed, having the greatest density near the nip of the flared opening.

In accordance with another aspect of the invention, the binder is formed by a first S-shaped portion; a second S-shaped portion, complementary to the first portion; and a partial ellypse joining a mid- region of the first portion to a mid-region of the second portion. The S-shaped members can have tapered ends. The S-shaped member desirably has a stem and legs, with the legs forming an angle in the range between 45 and 90 degrees with respect to the stem. The divergence of the entry panels facilitate the insertion of the cover, and any included contents, and simultaneously provide the desired grip. In order to assure the presence of the desired flare at the opening, a detent line extends along the length of the spine at the position of divergence of the lips forming the flare.

In accordance with a further aspect of the invention a method of inserting sheets within a binder is provided in which a binder has first and second panels diverging at . an opening of an otherwise closed elongated member and longitudinal edges of sheets are directly inserted into the opening. The sheets can be inserted at an angle to the opening over a portion of the length of the binder. The sheets can be assembled in a cover before insertion into the binder. The cover can have an edge fold that engages a protuberance with the binder, and the cover can include an internal resin layer to increase the adherence of sheets.

Description of the Drawings

Other aspects of the invention will become apparent after considering several illustrated embodiments taken in conjunction with the drawings in which:

Figure 1 is perspective view showing the insertion of a cover folder into a binder spine in accordance with the invention.

Figure 2 is a perspective view of a portion of a binder spine in accordance with the invention;

Figure 2a is an end view of the binder spine of Figure 2 illustrating the flared opening and other features of the invention;

Figure 3 is a perspective view of a folded cover for use with the binder spine of figure 2.

DETAILED DESCRIPTION

With respect to the drawings. Figure 1 shows the insertion of a cover (C) into a binder (B) .

The particular cover (C) has a folded edge (11) that forms a lip (12) . In addition, the exterior surface of the folder has an adhesive strip (13) .

In the insertion of the cover (C) into the binder (B) , the spine (21) is gripped by one hand as indicated, and the cover (C) is gripped, for example between the thumb and index fingers of the other hand, also as shown in figure 1. The edge (11) is then inserted between the panels (22-1) and (22-2) of the binder (B) . This is by a contrast with the procedure commonly employed for the insertion of a cover where, because of desired spring action at the open ends of the spine which form a nip, it is necessary to insert the cover by placing its end into the open end of the spine and then slide it along the spine.

The invention, because of the distinctive panels (22-1) and (22-2) permits the direct insertion of the cover into the spine. As indicated in Figure 1, a lower end (14-1) is shown inserted into the opening between the panels (22-1) and (22-2) and the upper end (14-2) is moved in the direction indicated by the arrow (A) until it is in the mouth of the panels (22-1) and (22-2) of the binder (B) .

Details of the binder (B) are illustrated in Figures 2 and 2A. The binder includes a curved spine (21) that extends continuously from one of the panels (22-1) to an opposite panel (22-2). It forms an interior opening to receive the edge (11) of the cover (C) and any contents held by the cover (C) . In order to increase the flare of the panels and the desired crimping action, a detent line (23-1) extends the entire length of the panel (21-1) . A similar line (23-2) (not visible in Figure 2) extends along the opposite side with respect to the second panel 21-1. The spine includes a set of gripper embossments (24) which are unevenly spaced, with their greatest density near the detent lines 23-1 and 23-2.

As indicated in Figure __-_, one or more protuberances (25-1 and 25- 2) may be included within the interior of the binder (B) . It will be appreciated that a single such protuberance (e.g., 25-1) is sufficient and can be used to engage the fold of the cover. In addition, as shown in Figure 2A, the nip area (23-1 and 23-2) is coated with an adhesive material which enhances the security of the binding. Projections (not shown) may also be included at the nip area (23-1 and 23-2) to increase the binding effect.

It is to be noted that for the cover (C) shown in Figure 3, a grip coating 13 is included. This contacts the mating surface of the nip for the binder and, enhances the binding.

In a preferred form of the invention, the angle between the panels 21-1 and 21-2 is from about about 45° to about 90°. The angle may be widened to as much as 135 . Where the spine is to be used with relatively thin materials, the angle may be reduced to as little as 30 . In practice it has been discovered that an angle of less than 30 interfere with the insertion of the cover into the spine as pictured in Figure 1.

The binder B is preferably formed from a thermoplastic material which is easily extruded. Polystyrene is suitable and is the preferred material for one-step extrusion process. A wide variety of other thermoplastic materials may be used such as polypropylene, polyvinylchloride and nylon.

The cover (C) is advantageously of polyvinylchloride but polystyrene, polypropylene or other thin-filmed materials may be used for other cover folders. Non-plastic materials may be used as well.

The friction coating that is employed on the outside surface of the cover (C) as well as along the inside at the nip of the binder itself is preferably a hot melt compound having good tack but poor adhesive bonding properties. A preferred hot melt of this type is principally ethylvinylacetate.