File including a curved retaining portion enabling an edge of a binding body to curve

A file includes a binding body which is superimposed with a plurality of binding sheets, a curved retaining portion which is curved in a direction in which the binding body extends when the cover is opened, a curved subsidiary portion arranged to fix a back portion thereof in a desired configuration. The binding body is provided adjacent to the curved retaining portion and has an arch-shape in a direction away from the inner side of a spine portion and the curved retaining portion is connected with a width less than a width of the spine portion to the inner side of the curved subsidiary portion at the outer side of the curved retaining portion to enable the end edge adjacently provided on the binding body to curve.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to files, and particularly, to files including a front cover portion and a back cover portion adjacently provided on both sides of a spine portion and further including clear pockets fastened between the front cover portion and the back cover portion, such as clear books and card albums.

2. Description of the Related Art

Conventionally, a file including clear pockets includes pockets that are made of clear films. The file including clear pockets is produced in an open state in which pockets are welded and fixed to the cover and file binding pockets are produced by melting the central portion of a stack of several pockets and welding the stack of pockets to the back portion of the cover.

In the file, the efficiency of page spread decreases when approaching both ends of the file due to the structure of the welded stack of pockets. Japanese Patent Application No. 5-32279, Japanese Utility Model Application No. 7-11434, and Japanese Patent Application No. 5-205490 disclose a file having an improved uniform spread at its center or at both ends by respectively welding each of a plurality of pockets to a cover.

Conventional files including pockets increasingly form a curve from a flat state as spread approaches the center by the thickness of the documents therein, even in a file in which each of the pockets is respectively welded to the cover, and as a result, efficiency of spread decreases.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of the present invention provide a file including binding sheets which can be easily spread flat when spreading a binding body.

In accordance with a preferred embodiment of the present invention, a file includes a binding body which is superimposed with a plurality of binding sheets, a curved retaining portion which is curved in the direction of the pocket sheets extending adhered and connected on the end edge of a group of pocket sheets when the cover is opened, and a curved subsidiary portion including a back that is fixed in a desired shape in a region on a front cover side and a region on a back cover side of a spine portion between the front cover portion and the back cover portion, wherein the binding body is provided adjacent to the curved retaining portion by providing an arch-shape in the direction of a front cover portion and back cover portion extending from the inner side of the spine portion, and the curved retaining portion is connected with a width less than the width of the spine portion to the inner side of the curved subsidiary portion at the outer side of the curved retaining portion to enable the end edge adjacently provided on the binding body to curve.

The binding body is preferably superimposed with a plurality of binding sheets and connected on the end edge which is connected to the front cover, wherein the curved retaining portion includes a front cover portion connected to the cover body between the front cover portion and the back cover portion, wherein the cover body includes a hinge portion between the front cover side and the back cover side, wherein said binding body is arranged such that the end edge of the group of pocket sheets connected to the cover body curves toward the side of the binding sheets extending when the cover body is opened, and wherein the curved subsidiary portion is spaced from the binding body and connected with the width less than the width of the spine portion at the outer side of the hinge portion of said front cover portion and the hinge portion of said back cover portion to enable the end edge of the binding body which is connected to the cover to curve.

The curved retaining portion may preferably include the hinge portion on the front cover side provided on the front cover portion, the hinge portion on the back cover side provided on the back cover portion, and an interjacent connecting portion interposed between said hinge portion on the front cover side and said hinge portion on the back cover side, and wherein said interjacent connecting portion is arranged to curve toward the direction of the binding sheets extending along with the end edge of the binging body connected to the cover by its weight when the cover body is opened.

The curved retaining portion may preferably include the hinge portion on the front cover side connected to the front cover portion, the hinge portion on the back cover side connected to the back cover portion, and the interjacent connecting portion interposed between the hinge portion on said front cover side and the hinge portion on said back cover side, and wherein the region on the front cover side leading to the hinge portion on the front cover side and the region on the back cover side leading to the hinge portion on the back cover side intersect at substantial right angles to the interjacent connecting portion when a load is not applied and define the interjacent connecting portion toward the direction of the binding sheets so as to be lifted with the elasticity adjacent to the hinge portion on the front cover side and the hinge portion on the back cover side when the cover is opened.

The distance between a folding portion of the curved subsidiary portion and the back cover portion may preferably be substantially equal to or less than the distance between the hinge portion on the front cover side of said curved retaining portion and the inner surface of the curved subsidiary portion and between the hinge portion on the back cover side and the inner surface of the curved subsidiary portion, wherein the hinge portion on the front cover side and the hinge portion on the back cover side are positioned adjacent to the end edge in the cross direction of the back cover portion when the cover body is closed, wherein the interjacent connecting portion between the hinge portion on the front cover side and the hinge portion on the back cover side is arranged to curve away from the back cover portion when the cover body is opened and the width of between the hinge portion on the front cover side and the hinge portion on the back cover side is less than the width of the back cover portion.

The interjacent connecting portion of the curved retaining portion may preferably be deformed plastically by hot pressing onto a synthetic resin sheet body so as to provide flexibility by reducing its thickness.

The binding body may preferably superimpose the plurality of binding sheets and is connected on the end edge which is connected to the cover, wherein the curved retaining portion is defined by the end edge connected to said binding body and a connecting body connecting the cover, wherein the cover body includes the front cover portion, the back cover portion, and the spine portion between said front cover portion and said back cover portion, defines the folding portion arranged to be spaced from the spine portion between the front cover portion and the back cover portion, the binding sheets are connected via said connecting body and the curved subsidiary portion is provided between the folding portion and the spine portion and in the spine portion, wherein said binding body is arranged to curve along the end edge of the binging body connected to the cover toward the direction in which the binding sheets extend when the cover body is opened, and wherein the curved retaining portion is connected adjacent to the folding portion of the front cover portion and the folding portion of the back cover portion and is spaced from the binding body to enable the end edge connected to the cover of the binding body with the short width to curve.

The connecting body may preferably include a connecting portion on the front cover side connected to the side of the front cover portion, a connecting portion on the back cover side connected to the side of the back cover portion and the interjacent connecting portion interposed between the connecting portion on the front cover side and said connecting portion on the back cover side, wherein the interjacent connecting portion connects the end edge connected to the cover of the binding body and is arranged to curve toward the binding sheets extending along with the end edge connected to the cover of the binding body by tension of the connecting portion on the front cover side and the connecting portion on the back cover side when the cover body is opened, and wherein the hinge portion is provided between the connecting portion on the front cover side and the interjacent connecting portion and between the connecting portion on the back cover side and the interjacent connecting portion.

The connecting body may preferably include the connecting portion on the front cover side connected to the side of the front cover portion, the connecting portion on the back cover side connected to the side of the back cover portion, and the interjacent connecting portion interposed between said connecting portion on the front cover side and the connecting portion on the back cover side, wherein the hinge portion on the front cover side and the hinge portion on the back cover side are disposed between the connecting portion on the front cover side and the interjacent connecting portion and between the connecting portion on the back cover side and the interjacent connecting portion, and wherein the connecting portion on the front cover side leading to the hinge portion on the front cover side and the connecting portion on the back cover side leading to the hinge portion on the back cover side intersect at substantial right angles with the interjacent connecting portion when a load is not applied and define the interjacent connecting portion toward the direction of the binding sheets as to be lifted with the elasticity adjacent to the hinge portion on the front cover side and the hinge portion on the back cover side when the cover is opened.

The distance between the folding portion of said front cover portion and the folding portion of said back cover portion may preferably be substantially the equal to or less than the distance between the hinge portion on the front cover side of said connecting body and the inner surface of the front cover portion and between the hinge portion on the back cover side and the inner surface of the back cover portion, wherein the hinge portion on the front cover side and the hinge portion on the back cover side are positioned adjacent to the end edge of the back cover portion when the cover body is closed, and wherein the interjacent connecting portion between the hinge portion on the front cover side and the hinge portion on the back cover side is arranged to curve away from the back cover portion when the cover body is opened and the width between the hinge portion on the front cover side and the hinge portion on the back cover side is less than the width of the back cover portion.

The interjacent connecting portion of the binding body may preferably be deformed plastically by hot press onto a synthetic resin sheet body so as to provide flexibility by reducing its thickness.

The binding sheets may preferably include pockets combined with thermoplastic resin sheets, wherein each binding sheet is hot-adhered to another on the end edge connected to the cover thereof, and wherein the end edge connected to the cover is arranged to curve inwardly when the binding sheets are opened.

The connecting body may preferably include a rigid sheet body made of a thermoplastic synthetic resin, include through-holes in the region connected to the binding body, and be arranged so as to curve.

According to various preferred embodiments of the present invention, a file includes a binding body which is superimposed with a plurality of binding sheets, a curved retaining portion which is curved toward the direction in which the pocket sheets extend, adhered and connected on the end edge of a group of pocket sheets when the cover is opened; and a curved subsidiary portion which fixes its back in a desired configuration in a region on a front cover side and a region on a back cover side of a spine portion between the front cover and the back cover. In this file, the binding body is provided adjacent to the curved retaining portion by providing an arch-shape toward the direction of a front cover portion and back cover portion extending from the inner side of the spine portion and the curved retaining portion is connected with the width less than the width of the spine portion to the inner side of the curved subsidiary portion at the outer side of the curved retaining portion to enable the end edge provided on the binding body to curve. Therefore, the file which can be easily spread flat when the binding body is spread is provided.

The binding body may preferably be superimposed with a plurality of binding sheets and connected on the end edge which is connected to the front cover. In this file, the curved retaining portion includes a front cover portion connected to the cover body between the front cover portion and the back cover portion, the cover body includes a hinge portion between the front cover side and the back cover side, the binding body is arranged such that the end edge of the group of pocket sheets connected to the cover body curve toward the side in which the binding sheets extend when the cover body is opened, and the curved subsidiary portion is spaced from the binding body and connected with the width less than the width of the spine portion at the outer side of the hinge portion of the front cover portion and the hinge portion of the back cover portion to enable the end edge of the binding body which is connected to the cover to curve. Therefore, the file which can be easily spread flat when the binding body is spread is provided.

The curved retaining portion may preferably include the hinge portion on the front cover side provided on the front cover portion, the hinge portion on the back cover side provided on the back cover portion, and an interjacent connecting portion interposed between the hinge portion on the front cover side and the hinge portion on the back cover side, and the intervenient assembly is arranged to curve toward the direction of the binding sheets extending along with the end edge of the binging body connected to the cover by its weight when the cover body is opened. Therefore, the file, which can be easily spread flat when the binding body is spread by expanding the portion provided adjacent to the interjacent connecting portion of the binding body, is provided.

The curved retaining portion may preferably include the hinge portion on the front cover side connected to the front cover portion, the hinge portion on the back cover side connected to the back cover portion and the interjacent connecting portion interposed between the hinge portion on the front cover side and the hinge portion on the back cover side, and the region on the front cover side extending to the hinge portion on the front cover side and the region on the back cover side extending to the hinge portion on the back cover side intersect at substantially right angles to the interjacent connecting portion when a load is not applied and define the interjacent connecting portion toward the direction of the binding sheets so as to be lifted with the elasticity adjacent to the hinge portion on the front cover side and the hinge portion on the back cover side when the cover is opened. Therefore, the binding sheets can be easily spread flat when the binding body is spread by curving the curved retaining portion away from the spine portion and expanding the portion provided adjacent to the curved retaining portion of the binding body.

The distance between a folding portion of the curved subsidiary portion and the back cover portion may preferably be substantially the equal to or less than the distance between the hinge portion on the front cover side of the curved retaining portion and the inner surface of the curved subsidiary portion and between the hinge portion on the back cover side and the inner surface of the curved subsidiary portion, and the hinge portion on the front cover side and the hinge portion on the back cover side are positioned adjacent to the end edge in the cross direction of the back cover portion when the cover body is closed. In this file, the interjacent connecting portion interposed between the hinge portion on the front cover side and the hinge portion on the back cover side is arranged to curve away from the back cover portion when the cover body is opened and the width between the hinge portion on the front cover side and the hinge portion on the back cover side is less than the width of the back cover portion. Therefore, the binding sheets can be easily spread flat when the binding body is spread by curving the curved retaining portion away from the spine portion and expanding the portion provided adjacent to the curved retaining portion of the binding body.

The interjacent connecting portion of the curved retaining portion may preferably be deformed plastically by hot press onto a synthetic resin sheet body so as to provide flexibility by reducing its thickness. By partially processing a region of the interjacent connecting portion, flexibility of the region can be easily increased.

The binding body may preferably superimpose the plurality of binding sheets and is connected on the end edge which is connected to the cover, and the curved retaining portion is defined by the end edge connected to the binding body and a connecting body connecting the cover. In this file, the cover body includes the front cover portion, the back cover portion, and the spine portion between the front cover portion and the back cover portion, the folding portion arranged to be spaced from the spine portion between the front cover portion and the back cover portion, the binding sheets are connected via said connecting body and the curved subsidiary portion is provided between the folding portion and the spine portion and in the spine portion. The binding body is arranged to curve along the end edge of the binging body connected to the cover in the direction that the binding sheets extend when the cover body is opened, and the curved retaining portion is connected adjacent to the folding portion of the front cover portion and the folding portion of the back cover portion so as to be spaced from the binding body in the cross direction to enable the end edge connected to the cover of the binding body with the short width to curve. Therefore, the binding sheets can be easily spread flat when the binding body is spread by curving the curved retaining portion away from the spine portion and expanding the portion adjacently provided to the curved retaining portion of the binding body.

The connecting body may preferably include a connecting portion on the front cover side connected to the side of the front cover portion, a connecting portion on the back cover side connected to the side of the back cover portion, and the interjacent connecting portion interposed between the connecting portion on the front cover side and the connecting portion on the back cover side, the interjacent connecting portion connects the end edge connected to the cover of the binding body and is arranged to curve toward the binding sheets extending along with the end edge connected to the cover of the binding body by tension of the connecting portion on the front cover side and the connecting portion on the back cover side when the cover body is opened, and the hinge portion is provided between the connecting portion on the front cover side and the interjacent connecting portion and between the connecting portion on the back cover side and the interjacent connecting portion. Therefore, the binding sheets can be easily spread flat when the binding body is spread by expanding the portion provided adjacent to the interjacent connecting portion of the binding body.

The connecting body may preferably include the connecting portion on the front cover side connected to the side of the front cover portion, the connecting portion on the back cover side connected to the side of the back cover portion, and the interjacent connecting portion interposed between said connecting portion on the front cover side and the connecting portion on the back cover side, the hinge portion on the front cover side and the hinge portion on the back cover side are provided between the connecting portion on the front cover side and the interjacent connecting portion and between the connecting portion on the back cover side and the interjacent connecting portion; and the connecting portion on the front cover side extending to the hinge portion on the front cover side and the connecting portion on the back cover side extending to the hinge portion on the back cover side intersect at substantial right angles to the interjacent connecting portion when a load is not applied and define the interjacent connecting portion toward the direction of the binding sheets so as to be lifted with the elasticity adjacent to the hinge portion on the front cover side and the hinge portion on the back cover side when the cover is opened. Therefore, the binding sheets can be easily spread flat when the binding body is spread by curving the interjacent connecting portion away from a spine portion and expanding the portion adjacently provided to the interjacent connecting portion of the binding body.

The distance between the folding portion of the front cover portion and the folding portion of the back cover portion may preferably be substantially equal to or less than the distance between the hinge portion on the front cover side of the connecting body and the inner surface of the front cover portion and between the hinge portion on the back cover side and the inner surface of the back cover portion, the hinge portion on the front cover side and the hinge portion on the back cover side are positioned adjacent to the end edge of the back cover portion when the cover body is closed, and the interjacent connecting portion between the hinge portion on the front cover side and the hinge portion on the back cover side is arranged to curve away from the back cover portion when the cover body is opened and the width between the hinge portion on the front cover side and the hinge portion on the back cover side is less than the width of the back cover portion. Therefore, the binding sheets can be easily spread flat when the binding body is spread by curving the connecting body away from the spine portion and expanding the portion adjacently provided to the curved retaining portion of the binding body.

The interjacent connecting portion of the binding body may preferably be deformed plastically by hot press onto a synthetic resin sheet body so as to provide flexibility by reducing its thickness. By partially processing a region of the interjacent connecting portion, flexibility of the region can be easily increased.

The binding sheets may preferably include pockets combined with thermoplastic resin sheets, each binding sheet is hot-adhered to another on the end edge connected to the cover thereof, and the end edge connected to the cover is arranged to curve inwardly when the binding sheets is opened. Therefore, the binding sheets can be easily spread flat when the binding body is spread by expanding the connecting portion of the binding body adjacently provided to the curved retaining portion.

The connecting body may preferably include a rigid sheet body made of thermoplastic synthetic resin, including through-holes in the region connected to the binding body, and arranged to curve. Therefore, the binding sheets can be easily spread flat when the binding body is spread by expanding the connecting portion of the binding body provided adjacent to the connecting body.

The above and other objects, features, and advantages of this invention will become more readily apparent from the following description of detailed description of preferred embodiments with reference to the accompanying drawings

In this specification and scope of the claims, the terms generally used are adopted for the cover height of the file and the cover width of the spine and the width of the spine, H is for the cover height, W is for the cover width and T, for the width of the spine inFIG. 66for your reference.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1is a schematic perspective view of a pocket file in accordance with a preferred embodiment of the present invention andFIG. 2is a schematic perspective view of the pocket file in an opened state as shown inFIG. 1.FIG. 3is a schematic longitudinal section view of the pocket file in a closed state as shown inFIG. 1.

A file10includes a cover body including a front cover portion12preferably made of a synthetic-resin, such as polypropylene, for example, a back cover portion14, and a spine portion16extending between the front cover portion12and the back cover portion14. A group of pocket sheets30, which define a binding body, superimposes a pocket sheet18as a binding sheet and is welded and connected to a connecting end edge of the group of pocket sheets30by being fastened to the group of pocket sheets30connected at an end edge which is connected to the spine portion16.

The file10preferably includes a curved retaining portion configured to curve the end edge of the group of pocket sheets30toward the side of the pocket sheet18extending at the inner side of the spine portion16between the front cover portion12and the back cover portion14when the cover is opened. The file10further includes a curved subsidiary portion which is fixed the back of the cover body in a desired shape in a region on a front cover side and a region on a back cover side of the spine portion16between the front cover portion12and the back cover portion14.

The front cover portion12and the back cover portion14are arranged to cross the spine portion16at a substantially right angle via a linear front adjacently providing portion20and a linear back adjacently providing portion22crossing from the top edge to the bottom edge in the direction of the height of the front cover portion12and the back cover portion14.

The pocket sheets18are flexibly arranged between a portion at which the pocket sheet18is fastened to the spine portion16and a portion disposed above a front folding portion24and a back folding portion26.

The pocket sheet18includes a linear outer end edge32, a linear bottom edge34and a opening edge36provided at a top end edge opposite from the bottom edge34and is connected to the inner surface of the spine portion16at an inner end edge38opposite from the linear outer end edge32.

The pocket sheet18preferably includes a pocket portion40configured to accommodate an object to be bound S, such as documents, for example, and is fitted for a mount42extending in the direction away from a portion at which the spine portion16is fastened to be inserted from a portion above the front folding portion24and the back folding portion26in the inner side of the pocket portion40.

As shown in any one ofFIGS. 3 to 6, the front folding portion24and the back folding portion26extending from the top edge to the bottom edge are arranged adjacent to the front connecting portion20and the back connecting portion22of the front cover portion12, the back cover portion14and the spine portion16, and the grip portion28is provided in a region extending from the front folding portion24on the front cover portion12to the spine portion16, the region extending from the back folding portion26on the back cover portion14to the spine portion16, and the spine portion16.

In the grip portion28, the connecting portion on a front cover side52including the front folding portion24as an axis moves upwardly in the region on the spine portion16on the front cover side between the front cover portion12and the back cover portion14, and the connecting portion on a back cover side54including the back folding portion26as an axis moves upwardly and the grip portion28forms the curved subsidiary portion which enables a connecting portion50as a curved subsidiary portion to arch upwardly, i.e. in a direction away from the spine portion16, when the front cover portion12and the back cover portion14are substantially horizontal, and the grip portion28becomes parallel to the horizontal spine portion16.

On the front cover portion12and the back cover portion14, the front folding portion24and the back folding portion26are preferably parallel or substantially parallel to the front adjacently providing portion20and the back adjacently providing portion22in the direction extending from the top edge to the bottom edge thereof adjacent to the front adjacently providing portion20and the back adjacently providing portion22.

The length of the inner surface of the spine portion16and the front folding portion24and the length of the inner surface of the spine portion16and the back folding portion26are preferably equal or substantially equal (shown inFIG. 4).

The mount42is provided such that the front folding portion24and the back folding portion26are not adjacent to the mount42.

The grip portion28preferably has an angular structure such that the user can set the spine portion16on his palm, grip the grip portion28with his fingers and open the pocket sheet18.

On the front cover portion12and the back cover portion14, a recess for searching70is preferably provided on the free end edge side opposite from the spine portion16, i.e. the left side end edge of the front cover portion12and the right side end edge of the back cover portion14, in the approximate middle of the direction of the height thereof.

The outer end edge of the recess for searching70and the outer end edge32of the pocket sheet18are substantially aligned with one another. Accordingly, with one hand, folding the file10with the cover closed, especially gripping the grip portion28and placing the other hand on the recess for searching70enables flipping the front cover portion12or the back cover portion14and the pocket sheet18.

The file10can be flipped from the pocket sheet18positioned on the upper side to the pocket sheet positioned on the lower side with the user's fingers placed on the outermost portion of the outer end edge32of the pocket sheet18and slightly bending the front cover portion12or the back cover portion14in the recess for searching70as shown inFIG. 20.

On the front cover portion12and the back cover portion14, a pair of a projection portions72on the upper side and the lower side are preferably respectively provided so as to cover the index i provided on the pocket sheet18such that the projection portion72projects towards the outer end edge32of the pocket sheet18on the outside of the region that the recess portion for searching70is provided.

The end edge of the group of pocket sheets30connected to the spine portion16when the cover body is opened is curved in a direction away from the spine portion16.

The pocket sheet18preferably includes pockets combined with thermoplastic resin sheets, for example. Each of the pocket sheets18is hot-adhered to another pocket sheet at the end edge thereof that is connected to the cover, and the end edge connected to the spine portion16is arranged to curve inwardly when the pocket sheet18is opened.

The group of pocket sheets30is connected by the end edge connected thereto and the connecting portion50connecting the front cover portion12and the back cover portion14.

The connecting body50is preferably defined by a substantially square rigid plate body when viewed in a planar view and made of thermoplastic synthetic resin, for example, and includes the curved retaining portion which curves the group of pocket sheets30, that are welded and connected at the connecting end edge of the group of pocket sheets30, towards a direction of the pocket sheet18which defines the binding body extending.

The connecting body50is preferably connected adjacent to the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14and may be spaced from the group of the pocket sheets30in a crossing direction such that the connecting body50enables the end edge of the group of pocket sheet30connected to the cover to curve with the width less than the width of the spine portion16of the cover body.

The connecting body50preferably includes a connecting portion on the front cover side52connected to the side of the front cover portion12, a connecting portion on the back cover side54connected to the side of the back cover portion14and an interjacent connecting portion56interposed between the connecting portion on the front cover side52and the connecting portion on the back cover side54. The interjacent connecting portion56is connected to the end edge of the group of pocket sheets30connected to the cover and is configured so as to curve away from the spine portion16along with the end edge of the group of the pocket sheets30connected to the cover by the tension of the connecting portion on the front cover side52and the connecting portion on the back cover side54when the cover is opened.

The interjacent connecting portion56is preferably relatively flexible and is arranged to curve away from the spine portion16by the weight of the pocket sheet18being in a spread state.

The connecting body50preferably includes a through hole58that is provided in the region connected to the binding body.

The connecting body50preferably includes a plurality of rectangular planar shaped through holes58that are spaced from one another and relative flexibility is provided thereto. In this preferred embodiment, three through holes are provided, i.e., an upper through hole58a, a lower through hole58b, and a middle through hole58c.

In this preferred embodiment, in the interjacent connecting portion56, a pair bridge portions56aand56bextend between the connecting portion on the front cover side52and the connecting portion on the back cover side54at the upper edge and the lower edge respectively. A bridge portion56cextends between the upper through hole58aand the middle through hole58cand a bridge portion56dextends between the middle through hole58cand the lower through hole58b. Therefore, the adhesion region of the connecting portion50and the group of pocket sheets30is provided by the bridge portions56ato56d.

Further, a longitudinal bridge portion56eis preferably provided between a hinge portion on the front cover side60and the upper through hole58a, the lower through hole58band the middle through hole58c, and a longitudinal bridge portion56fis preferably provided between a hinge portion on the back cover side62and the upper through hole58a, the lower through hole58band the middle through hole58c.

On the connecting portion50, the hinge portion on the front cover side60provided between the connecting portion on the front cover side52and the interjacent connecting portion56and the hinge portion on the back cover side62provided between the connecting portion on the back cover side54and the interjacent connecting portion56are arranged parallel or substantially parallel to each other.

The distance between the spine portion16and the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14, respectively, is preferably substantially equal to or shorter than the distance between the hinge portion on the front cover side60of the connecting body50and the inner surface of the front cover portion12and between the hinge portion on the back cover side62and the inner surface of the back cover portion14. The hinge portion on the front cover side60and the hinge portion on the back cover side62are arranged adjacent to the end edge of the spine portion16in a crossing direction when the cover is closed.

The interjacent connecting portion56between the hinge portion on the front cover side60and the hinge portion on the back cover side62is arranged to curve away from the spine portion16when the front cover portion12is opened and also the width between the hinge portion on the front cover side60and the hinge portion on the back cover side62is preferably less than the width of the spine portion16.

The hinge portion on the front cover side60is positioned inward of the front folding portion24and the hinge portion on the back cover side62is positioned inward of the back adjacently providing portion22such that the width (T2) between the hinge portion on the front cover side60and the hinge portion on the back cover side62is less than the width (T1) between the front adjacently providing portion20and the back adjacently providing portion22when the cover body is opened, i.e. when the connecting portion on the front cover side52and the connecting portion on the back cover side54are adjacent to one another in the horizontal plane in a flat state and the front cover portion12and the back cover portion14are adjacent to one another in the horizontal plane in the flat state.

Additionally, although the width (T1) between the front adjacently providing20and the back adjacently providing portion22and the width (T3) between the hinge portion on the front cover side60and the hinge portion on the back cover side62are substantially equal, (T3) is preferably less than the width (T1) by the thickness of the front adjacently providing portion20and the back adjacently providing portion22, since the hinge portion on the front cover side60and the hinge portion on the back cover side62is fastened to the inner surface of the front adjacently providing portion20and the back adjacently providing portion22when the cover body is closed, i.e. when the front cover portion12and the back cover portion14are parallel or substantially parallel and the connecting portion on the front cover side52and the connecting portion on the back cover portion54are parallel or substantially parallel.

Next, a method of manufacturing the file10shown inFIG. 1according to a preferred embodiment of the present invention will be described below with referring toFIGS. 6 through 14.

First, a synthetic resin sheet body, such as polypropylene or other suitable material, is prepared, Thompson processing is applied thereto and the cover material80is removed, which will be the cover of the file and will define a cover material80in a combined size of the front cover portion12, the back cover portion14and the spine portion16together.

Next, a spine index paper Z is pasted to the surface of the spine area, which will later become the spine portion16, with an adhesive agent (Spine index paper pasting step).

For example, as shown inFIGS. 6,7A, and7B, when a thermoplastic resin sheet is used as the cover material80, the heat-press molding is applied with the V-shape heater (not shown) to V-shape slots20A,22A,24A and26A which have a substantially V-shaped cross-section and are parallel to one another to form the front adjacently providing portion20, the back adjacently providing portion22, the front folding portion24and the back folding portion26. Then, the cover material80is formed to enable folding (V-shape slot molding step).

Next, as shown inFIG. 8, heat is applied to the V-shape slots20A,22A,24A and26A, the V-shape slots20A,22A,24A and26A are folded corresponding the front adjacently providing portion22and the back adjacently providing portion24, and the front adjacently providing portion20and the back adjacently providing portion22are molded by joining and solidifying the melted slot walls (adjacently providing portion formation step).

Then, the cover including the grip portion28is formed so as to include the front cover portion12, the back cover portion14, the spine portion16between the front cover portion12and the back cover portion14, the front folding portion24including the V-shape slot24A, and the back folding portion26including the V-shape slot26A.

First, a plurality of pocket sheets18is superimposed, and the edge faces of the inner end edge38are heated. Consequently, the region which is slightly inward of the inner end edge38is melted to fasten the plurality of pocket sheets18together. To apply hot welding to the inner end edge38of the pocket sheets18, a hot plate is pressed to the inner end edge38, the inner end edges38are welded and the edge faces of the inner end edge38facing one another are adhered to form the group of pocket sheets30. Adhesion and welding can also be performed with a hot-melt adhesive agent or by ultrasonic horn.

The group of pocket sheets30includes pockets combined with thermoplastic resin sheets, each binding sheet is hot adhered to another on the end edge connected to the cover thereof, and the end edge connected to the cover is formed to curve inwardly when the pocket sheet18is opened.

Next, a method for fixing the group of pocket sheets30to the spine portion16will be described with referring toFIGS. 9 and 13.

First, the connecting portion50having substantially square planar shape including a synthetic resin sheet body, such as polypropylene or other suitable material, is prepared.

The connecting body50includes the connecting portion on the front cover side52connected to the side of the front cover portion12, the connecting portion on the back cover side54connected to the side of the back cover portion14and the interjacent connecting portion56interposing between the connecting portion on the front cover side52and the connecting portion on the back cover portion54.

The interjacent connecting portion56is connected to the end edge connected to the cover of the binding body and is formed to curve away from the spine portion16along with the end edge connected to the cover of the group of the pocket sheets30by the tension of the connecting portion on the front cover portion52and the connecting portion on the back cover portion54when the cover is opened.

The connecting body50preferably includes a through hole58in the region connected to the group of pocket sheets30and is configured so as to curve. The group of pocket sheets30is adhered to the inner surface of the bridge portions56a,56b,56cand56dof the connecting body50and also to the inner surface of the longitudinal bridge portion56eand56fwith a slight space between the hinge portion on the front cover side60and the hinge portion on the back cover side62.

The group of pocket sheets30is applied hot welding to the upper surface of the interjacent connecting portion56.

The hinge portion on the front cover side60and the hinge portion on the back cover side62are formed between the connecting portion on the front cover side52and the interjacent connecting portion56and between the connecting portion on the back cover side54and the interjacent connecting portion56.

The distance between the spine portion16and the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14respectively is preferably substantially equal to or less than the distance between the hinge portion on the front cover side60of the connecting body50and the inner surface of the front cover portion12or the hinge portion on the back cover side62and the inner surface of the back cover portion14. The hinge portion on the front cover side60and the hinge portion on the back cover side62are preferably arranged adjacent to the end edge of the spine portion16in a crossing direction when the cover is closed.

The interjacent connecting portion56between the hinge portion on the front cover side60and the hinge portion on the back cover side62is configured to curve away from the spine portion16and the width between the hinge portion on the front cover side60and the hinge portion on the back cover side62is preferably less than the width of the spine portion16when the front cover portion12is opened.

Next, a method for adhering the group of pocket sheets30to the cover material80will be described.

The connecting body50is connected adjacent to the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14and preferably spaced from the group of the pocket sheets30in the crossing direction such that the connecting body50enables the end edge connected to the cover of the group of pocket sheets30to curve with the width less than the width of the spine portion16of the cover body.

The connecting body50is welded to the connecting portion on the front cover side52connected to the side of the front cover portion12and the inner surface of the front cover portion12and also to the connecting portion on the back cover side54on the side of the back cover portion14and the inner surface of the back cover portion14and is crosslinked between the front cover portion12and the back cover portion14.

In accordance with a preferred embodiment of the present invention, the connecting body50includes the connecting portion on the front cover side52connected to the side of the front cover portion12, the connecting portion on the back cover side54connected to the side of the back cover portion14and the interjacent connecting portion56interposed between the connecting portion on the front cover side52and the connecting portion on the back cover portion54. The interjacent connecting portion56is connected to the end edge connected to the cover of the binding body and is configured to curve away from the spine portion16along with the end edge connected to the cover of the binding body by the tension of the connecting portion on the front cover portion52as the rigid body and the connecting portion on the back cover portion54as the rigid body when the cover body is opened.

In the connecting body50, the hinge portion is preferably provided between the connecting portion on the front cover side52and the interjacent connecting portion56and between the connection portion on the back cover side54and the interjacent connecting portion56.

The distance (W1) between the spine portion16and the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14, respectively, is preferably substantially equal to the distance (W2) between the hinge portion on the front cover side60of the connecting body50and the inner surface of the front cover portion12or the hinge portion on the back cover side62and the inner surface of the back cover portion14and (W2) is less than (W1) by the thickness of the spine portion16.

The hinge portion in the front cover side60and the hinge portion on the back cover side62are positioned adjacent to the end edge of the spine portion16in a crossing direction when the cover body is closed. The hinge portion on the front cover side60and the hinge portion on the back cover side62are configured to curve away from the spine portion16when the cover body is opened and the width between the hinge portion on the front cover side60and the hinge portion on the back cover side62is less than the width of the spine portion16. Accordingly, when the cover body is opened and the group of pocket sheets30is spread thereby, the pocket sheet18is relatively flat.

The present invention is not limited to the preferred embodiments previously described. For example, in the connecting body50, as shown inFIGS. 18 and 19, the distance between the spine portion16and the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14, respectively, may preferably be less than the distance between the hinge portion on the front cover side60of the connecting body50and the inner surface of the front cover portion12or the hinge portion on the back cover side62and the inner surface of the back cover portion14.

By using this method, the region of the interjacent connecting portion56may we weighed down with the group of pocket sheets30toward the side of the spine portion16. Therefore, to retain the interjacent connecting portion56and the spine portion16so as to be substantially parallel, a void between the interjacent connecting portion56and the spine portion16may be filled with foam or other suitable material.

Additionally, as shown inFIGS. 16 and 17, the hinge portion is disposed adjacent to the front folding portion24at the connecting portion on the front cover side52and the back folding portion26at the connecting portion on the back cover side54. The group of pocket sheets30may preferably be configured to be spread flat by curving the interjacent connecting portion56away from the spine portion16due to the weight of the pocket sheet18when the pocket sheet18is opened toward the sides of the front cover portion12and the back cover portion14.

FIG. 21is a schematic perspective view of the pocket file in accordance with an embodiment of the present invention,FIG. 22is a schematic perspective view of the pocket file in accordance with an opened state as shown inFIG. 21.FIG. 23is a schematic transverse sectional view of the pocket file in a closed state as shown inFIG. 21.

A file110includes a cover body including a front cover portion112made of synthetic-resin, such as polypropylene, for example, a back cover portion114, and a spine portion116provided between the front cover portion112and the back cover portion. A group of pocket sheets130superimposes a pocket sheet118and is welded and connected to a connecting end edge of the group of pocket sheets130by being fastened the group of pocket sheets130as the binding body connected at an end edge which is connected to the spine portion116.

The file110preferably includes a curved subsidiary portion which is fixed to the back of the cover body in regions on a front cover side and on a back cover side of the spine portion116between the front cover portion112and the back cover portion114and the curved retaining portion configured to curve the end edge of the group of pocket sheets130towards a direction of the pocket sheet118extending at the inner side of the spine portion116adjacently provided between the front cover portion112and the back cover portion114when the cover is opened.

The front cover portion112and the back cover portion114, as shown inFIGS. 23 through 26, define a curved subsidiary portion which causes the back of the binding body to have a particular shape in a region on a front cover side and a region on a back cover side of the spine portion116between the front cover portion112and the back cover portion114. In this embodiment, the curved subsidiary portion is defined by an independent curved subsidiary member128.

The front cover portion112and the back cover portion114are provided adjacent to the spine portion116so as to extend at a substantially right angle via a linear front folding portion124and a linear back folding portion126and a linear front adjacently providing portion120and a linear back adjacently providing portion122extending from the top edge to the bottom edge in the direction of the distance of the front cover portion112and the back cover portion114when the cover body is closed.

The pocket sheets118are flexibly provided between a portion at which the pocket sheet118is fastened to the inner side of the spine portion116between the front cover portion112and the back cover portion114and a portion disposed at least above a front folding portion124and a back folding portion126(when the cover body is closed).

The pocket sheets118include a linear outer end edge132, a linear bottom edge134, and an opening edge136provided at a top end edge which is opposite to the bottom edge134and is connected to the inner surface of the spine portion116at an inner end edge138opposite to the linear outer end edge132.

The pocket sheet118includes a pocket portion140arranged to accommodate an object to be bound S, such as documents, and includes a mount142extending in a direction away from a portion at which the spine portion116is fastened to be inserted from a portion above the front folding portion124and the back folding portion126(when the cover body closed) in the inner side of the pocket portion140.

The group of pocket sheets130is connected by a curved retaining portion150provided adjacent to the front cover portion112and the back cover portion114at the connecting end edge connected to the group of pocket sheets130.

The curved retaining portion150is preferably defined by a substantially square rigid plate body when viewed in a planar view that is made of thermoplastic synthetic resin and includes the curved retaining portion which curves the group of pocket sheets130that are welded and connected thereto at the connecting end edge of the group of pocket sheets130, in a direction away from the spine portion116when the cover body is opened.

The curved retaining portion150is connected adjacent to the outer side of the hinge portion on a front cover side160and the outer side of the hinge portion on a back cover side162and is preferably spaced from the group of the pocket sheets130in the crossing direction such that the curved retaining portion150enables the end edge connected to the cover of the group of pocket sheet130to curve with a width that is less than the width of the spine portion116of the curved subsidiary portion128.

The curved retaining portion150includes the connecting portion on a front cover side152adjacently provided in the side of the front cover portion112, the connecting portion on a back cover side154adjacently provided in the side of the back cover portion114, and an interjacent connecting portion156interposed between the connecting portion on the front cover side152and the connecting portion on the back cover portion154. The interjacent connecting portion156is connected to the end edge connected to the cover of the group of pocket sheets130and is configured to curve away from the spine portion116along with the end edge connected to the cover of the group of the pocket sheets130by the tension of the connecting portion on the front cover side152and the connecting portion on the back cover side154when the cover is opened.

The curved retaining portion150is relatively flexible and is configured to arch away from the spine portion116by the weight of the pocket sheet118being in a spread state.

The front cover portion112and the connecting portion on the front cover side152are defined by unified flat plate, and the back cover portion114and the connecting portion on the back cover side154are also defined by a unified flat plate.

The curved retaining portion150is preferably a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, having a square planar shape and includes a through hole58in the region connected to the binding body and is configured so as to curve.

The curved retaining portion150includes a plurality of rectangular planar shaped through holes158which are spaced from one another and flexibility is provided thereto. In this preferred embodiment, 6 through holes are provided, an upper through hole158a, a lower through hole158b, and middle through holes158c1,158c2,158c3and158c4.

In this preferred embodiment, in the interjacent connecting portion156, bridge portions156aand156bare provided between the connecting portion on the front cover side152and the connecting portion on the back cover side154at the upper edge and the lower edge, respectively. Bridge portions156c1,156c2,156c3and156c4are provided between middle through holes158c1and158c4and the bridge portion56c5is provided between the middle through hole158c4and the lower through hole158b. Therefore, the adhesion region of the group of pocket sheets130and the interjacent connecting portion156is provided.

Further, a longitudinal bridge portion156eis provided between a hinge portion on the front cover side160and the upper through hole158a, the lower through hole158band the middle through holes158c1,158c2,158c3, and158c4, and a longitudinal bridge portion156fis provided between a hinge portion on the back cover side162and the upper through hole158a, the lower through hole158band the middle through holes158c1,158c2,158c3and158c4.

The longitudinal bridge portion156eand the longitudinal bridge portion156fare successively arranged so as to extend from the top edge to the bottom edge of the cover body.

On the curved retaining portion150, the hinge portion on the front cover side160provided between the connecting portion on the front cover side152and the interjacent connecting portion156and the hinge portion on the back cover side162provided between the connecting portion on the back cover side154and the interjacent connecting portion156are parallel or substantially parallel to each other.

The distance between the spine portion116and the front folding portion124of the front cover portion112and the back folding portion126of the back cover portion114, respectively, is preferably substantially equal or less than the distance between the hinge portion on the front cover side160of the curved retaining portion150and the inner surface of the front cover portion112and the hinge portion on the back cover side162and the inner surface of the back cover portion114. The hinge portion on the front cover side160and the hinge portion on the back cover side162are preferably arranged adjacent to the end edge of the spine portion116in a crossing direction when the cover body is closed.

The interjacent connecting portion156between the hinge portion on the front cover side160and the hinge portion on the back cover side162is configured to curve away from the spine portion116when the front cover portion112is opened and the width between the hinge portion on the front cover side160and the hinge portion on the back cover side162is preferably less than the width of the spine portion116.

The front cover portion112and the back cover portion114, as shown inFIGS. 23 through 26, define a curved subsidiary portion which causes the back of the binding body to have a particular shape in a region on a front cover side and a region on a back cover side of the spine portion116between the front cover portion112and the back cover portion114. In this preferred embodiment, the curved subsidiary portion is defined by an independent curved subsidiary member128.

The curved subsidiary member128is preferably a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, and has a substantially square planar shape. The front folding portion124and the back folding portion126extending from the upper edge to the lower edge are successively provided and the curved subsidiary portion128is provided in the region from the front folding portion124on the front cover portion112to the spine portion116, the region from the back folding portion126on the back cover portion114to the spine portion116and the spine portion116.

In curved subsidiary member128, the connecting portion on the front cover side152including the front folding portion124as an axis moves upwardly in the region on the spine portion116on the front cover side extending between the front cover portion112and the back cover portion114, and the connecting portion on the back cover side154including the back folding portion126as an axis moves upwardly and the curved subsidiary portion128defines the curved subsidiary portion which enables the curved retaining portion150to arch upwardly, i.e. in the direction away from the spine portion116, when the front cover portion112and the back cover portion114are substantially horizontal and parallel to the curved subsidiary member128of the horizontal spine portion116.

On the front cover portion112and the back cover portion114, the front folding portion124and the back folding portion126are parallel or substantially parallel to the front adjacently providing portion120and the back adjacently providing portion122in a direction of their heights extending from the top edge to the bottom edge thereof adjacent to the front adjacently providing portion120and the back adjacently providing portion122.

The length of the inner surface of the spine portion116and the front folding portion124and the length of the inner surface of the spine portion116and the back folding portion126are preferably equal or substantially equal to each other (shown inFIG. 24).

A square shape retaining portion121adjacently provided via the front adjacently providing portion120on the side of the front adjacently providing portion120of the spine portion116is provided and a square shape retaining portion123adjacently provided via the back adjacently providing portion122on the side of the back adjacently providing portion122is provided.

A square shape fastening portion on the front cover side125is adjacently provided via the front folding portion124on the side of the front folding portion124of the shape retaining portion121and a square shape fastening portion on the back cover side127is adjacently provided via the back folding portion126on the side of the back folding portion126.

The curved subsidiary member128has an angular structure such that the user can set the spine portion116on his palm, grip the grip portion128with his fingers, and open the pocket sheet118.

On the front cover portion112and the back cover portion114, a recess for searching170is preferably provided on the free end edge side opposite to the spine portion116, i.e. the left side end edge of the front cover portion112and the right side end edge of the back cover portion114, in the approximate middle of the direction of the height thereof.

The outer end edge of the recess for searching170and the outer end edge132of the pocket sheet118are preferably substantially aligned. Accordingly, with one hand, folding the file110with the cover closed, especially gripping the curved subsidiary portion128and placing the other hand to the recess for searching170enables flipping of the front cover portion112or the back cover portion114and the pocket sheet118.

The file110can be flipped from the pocket sheet118positioned on the upper side to the pocket sheet positioned on the lower side with the user's fingers placed the outermost portion of the outer end edge132of the pocket sheet118and slightly bend the front cover portion112or the back cover portion114in the recess for searching170as shown inFIG. 20.

On the front cover portion112and the back cover portion114, a pair of projection portions172are provided on the upper side and the lower side, respectively, to cover the index i provided on the pocket sheet118such that the projection portion172is projected toward the outer side from the end edge for spreading, i.e. the outer end edge132, of the pocket sheet118on the outside of the region in which the recess portion for searching170is provided.

The end edge of the group of pocket sheets130connected to the spine portion116when the cover body is opened is curved away from the spine portion116.

The pocket sheet118includes pockets combined with thermoplastic resin sheets, each pocket sheet118is hot-adhered to another pocket sheet118on the end edge connected to the cover thereof, and the end edge connected to the spine portion116is configured so as to curve inwardly when the pocket sheet118is opened.

The hinge portion on the front cover side160is preferably arranged inwardly from the front folding portion124and the hinge portion on the back cover side162is preferably arranged inwardly from the back adjacently providing portion122such that the width (T2) between the hinge portion on the front cover side160and the hinge portion on the back cover side162is preferably less than the width (T1) between the front adjacently providing portion120and the back adjacently providing portion122when the cover body is opened, i.e. when the connecting portion on the front cover side152and the connecting portion on the back cover side154are apposed at the horizontal plane in a flat state and the front cover portion112and the back cover portion114are adjacent to one another in the horizontal plane in the flat state.

Additionally, although the width (T1) between the front adjacently providing portion120and the back adjacently providing portion122and the width (T3) between the hinge portion on the front cover side160and the hinge portion on the back cover side162are substantially equal, (T3) is less than T1by the thickness of the front adjacently providing portion120and the back adjacently providing portion122than (T1) since the hinge portion on the front cover side160and the hinge portion on the back cover side162is fastened to the inner surface of the front adjacently providing portion120and the back adjacently providing portion122when the cover body is closed, i.e. when the front cover portion112and the back cover portion114are parallel or substantially parallel and the connecting portion on the front cover side152and the connecting portion on the back cover portion154are parallel or substantially parallel.

Next, a method of manufacturing the file110shown inFIG. 21according to a preferred embodiment of the present invention will be described below with referring toFIGS. 27 through 32.

First, a plurality of pocket sheets118is superimposed, and the edge faces of the inner end edge138that face one another are heated. Consequently, the region which is slightly inward from the inner end edge138is melted to fasten the plurality of pocket sheets118together. To apply hot welding to the inner end edge138of the pocket sheets118, a hot plate is pressed to the inner end edge138, the vicinity of the inner end edge138is welded and the edge surfaces of the inner end edge138facing one another are adhered to form the group of pocket sheets130. Adhesion and welding can be performed using a hot-melt adhesive agent or by ultrasonic horn.

The group of pocket sheets130preferably includes pockets combined with thermoplastic resin sheets, each binding sheet is hot adhered to another on the end edge connected to the cover thereof, and the end edge connected to the cover is configured to curve inwardly when the pocket sheet118is opened.

Next, a method for fixing the group of pocket sheets130to the curved retaining portion150of the cover body will be described with referring toFIGS. 29 through 34.

First, a synthetic resin sheet body, such as polypropylene or other suitable material is prepared, Thompson processing is applied thereto and the cover material180is removed, which will define the cover of the file and will form a cover material180including the combination of the front cover portion112, the back cover portion114, and the curved retaining portion150.

For forming the curved retaining portion150with the cover material180preferably made of a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, in a square planar shape, the curved retaining portion150is formed by demarcating the interjacent connecting portion156interposed between the connecting portion on the front cover side152connected to the front cover portion112and the connecting portion on the back cover side154connected to the back cover portion114from the cover material180.

The interjacent connecting portion156is connected to the end edge connected to the cover of the binding body and is configured to curve away from the spine portion116along with the end edge connected to the cover of the group of the pocket sheets130by the tension of the connecting portion on the front cover portion152and the connecting portion on the back cover portion154when the cover is opened.

The curved retaining portion150is preferably made of a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, in a square planar shape and includes the through hole158in the region connected to the group of pocket sheets130and is configured so as to curve. The group of pocket sheets130is adhered to the inner surface of the bridge portions156a,156b,156c1,156c2,156c3,156c4and156c5of the curved retaining portion150and to the inner surface of the longitudinal bridge portion156eand156fwith a space between the hinge portion on the front cover side160and the hinge portion on the back cover side162.

Hot welding is applied to the group of pocket sheets130along the upper surface of the interjacent connecting portion156.

The curved retaining portion150is defined by the hinge portion on the front cover side160and the hinge portion on the back cover side162between the connecting portion on the front cover side152and the interjacent connecting portion156and between the connecting portion on the back cover side154and the interjacent connecting portion156.

The distance between the spine portion116and the front folding portion124of the front cover portion112and the back folding portion126of the back cover portion114, respectively, is preferably substantially equal to or less than the distance between the hinge portion on the front cover side160of the curved retaining portion150and the inner surface of the front cover portion112or the hinge portion on the back cover side162and the inner surface of the back cover portion114. The hinge portion on the front cover side160and the hinge portion on the back cover side162are arranged adjacent to the end edge of the spine portion116in crossing direction when the cover is closed.

The interjacent connecting portion156interposed between the hinge portion on the front cover side160and the hinge portion on the back cover side162is configured to curve away from the spine portion116and the width between the hinge portion on the front cover side160and the hinge portion on the back cover side162is preferably less than the width of the spine portion116when the front cover portion112is opened.

Next, a method for adhering the group of pocket sheets130to the cover material180will be described.

The curved retaining portion150is connected adjacent to the hinge portion on the front cover side160of the front cover portion112and the hinge portion on the back cover side162of the back cover portion114and spaced from the group of the pocket sheets130in the crossing direction such that the connecting body150enables the end edge connected to the cover of the group of pocket sheet130to curve with the width less than the width of the spine portion116of the cover body.

The connecting body150is welded to the connecting portion on the front cover side152connected to the side of the front cover portion112and the outer surface of the front cover portion112and to the connecting portion on the back cover side154on the side of the back cover portion114and the outer surface of the back cover portion114and extends between the front cover portion112and the back cover portion114.

In accordance with a preferred embodiment of the present invention, the curved retaining portion150includes the connecting portion on the front cover side152connected to the side of the front cover portion112, the connecting portion on the back cover side154connected to the side of the back cover portion114, and the interjacent connecting portion156interposed between the connecting portion on the front cover side152and the connecting portion on the back cover portion154. The interjacent connecting portion156is connected to the end edge connected to the cover of the binding body and is configured to curve away from the spine portion116along with the end edge connected to the cover of the binding body by the tension of the connecting portion on the front cover portion152and the connecting portion on the back cover portion154when the cover body is opened.

In the curved retaining portion150, the hinge portion on the front cover side160, and the hinge portion on the back cover side162are arranged between the connecting portion on the front cover side152and the interjacent connecting portion156and between the connection portion on the back cover side154and the interjacent connecting portion156.

Next, in order to form the curved subsidiary portion128, a thermoplastic synthetic resin sheet is prepared, Thompson processing is applied thereto, and the curved subsidiary portion128is punched out in a square planar shape.

Further, a spine index paper Z is pasted to the surface of the spine area, which will become the spine portion116, using an adhesive agent (Spine index paper pasting step).

For example, as shown inFIGS. 26 and 27, when a thermoplastic resin sheet is used for the curved retaining portion128, the heat-press molding is applied with the V-shape heater (not shown) to form V-shape slots120A,122A,124A and126A which have a substantially V-shaped section and which are parallel or substantially parallel to one another to define the front adjacently providing portion120, the back adjacently providing portion122, the front folding portion124, and the back folding portion126. Then, the cover material180is formed in order to enable the cover material180to fold (V-shape slot molding step).

Then, the cover body including the curved subsidiary portion128is formed by fastening the outer end edge of the front adjacently providing portion120to the outer surface of the front cover portion112and a portion outward from the hinge portion on the front cover side160and also fastening the back adjacently providing portion122to the outer surface of the back cover portion114and a portion outward from the hinge portion on the back cover side162.

The distance (W1) between the spine portion116and the front folding portion124of the front cover portion112and the back folding portion126of the back cover portion114respectively is substantially equal to the distance (W2) between the hinge portion on the front cover side160of the curved retaining portion150and the inner surface of the front cover portion112or the hinge portion on the back cover side162and the inner surface of the back cover portion114and (W2) is less that (W1) by the thickness of the spine portion116.

The hinge portion in the front cover side160and the hinge portion on the back cover side162are positioned adjacent to the end edge of the spine portion116when the cover body is closed. The hinge portion on the front cover side160and the hinge portion on the back cover side162are configured to curve away from the spine portion116when the cover body is opened and the width between the hinge portion on the front cover side160and the hinge portion on the back cover side162is less than the width of the spine portion116. Accordingly, when the cover body is opened and the group of pocket sheets130are spread, the pocket sheet118is substantially flat.

FIG. 35is a perspective view of a pocket file in accordance with another preferred embodiment of the present invention andFIG. 36is a schematic perspective view of the pocket file in an open state as shown inFIG. 35.FIG. 37is a schematic longitudinal section view of the pocket file in a close state as shown in FIG.35.

A file310includes a cover body including a front cover portion312preferably made of synthetic-resin, such as polypropylene, for example, a back cover portion314, and a spine portion316provided between the front cover portion312and the back cover portion314. A group of pocket sheets330are superimposed with a pocket sheet318and is welded and connected to the a connecting end edge of the group of pocket sheets330by being fastened the group of pocket sheets330connected at a end edge which is connected to the spine portion316.

The file310includes a curved subsidiary portion328which fixes the back of the cover body in a particular configuration in regions on a front cover side and on a back cover side of the spine portion316between the front cover portion312and the back cover portion314and the curved retaining portion352configured to curve the end edge of the group of pocket sheets330towards the pocket sheet318extending at the inner side of the spine portion316adjacently provided between the front cover portion312and the back cover portion314when the cover is opened.

The front cover portion312and the back cover portion314are arranged adjacent to the spine portion316so as to cross at a substantial right angle via a linear front folding portion324and a linear back folding portion326and a linear front adjacently providing portion320and a linear back adjacently providing portion322extending from the top edge to the bottom edge in the direction of the height of the front cover portion312and the back cover portion314.

The pocket sheets318are flexibly provided between a portion at which the pocket sheets318are fastened to the inner side of the spine portion316between the front cover portion312and the back cover portion314and a portion at least above the front folding portion324and the back folding portion326(when the cover body is closed).

The pocket sheet318includes a linear outer end edge332, a linear bottom edge334, and an opening edge336provided at a top end edge which is opposite to the bottom edge334and is connected to the inner surface of the spine portion316at the inner end edge338opposite to the linear outer end edge332.

The pocket sheet318includes a pocket portion340arranged to accommodate an object to be bound S, such as documents, and is configured for a mount342extending in a direction away from a portion at which the spine portion316is fastened to be inserted from a portion above the front folding portion324and the back folding portion326(when the cover body is closed) in the inner side of the pocket portion340.

The group of pocket sheets330is connected by the curved retaining portion350provided adjacent to the front cover portion312and the back cover portion314at the connecting end edge connected to the group of pocket sheets330.

A curved retaining portion350is preferably a substantially square rigid plate body when viewed in a planar view and made of thermoplastic synthetic resin and includes the curved retaining portion350which curves the group of pocket sheets330, which are welded and connected at the connecting end edge of the group of pocket sheets330, toward the direction in which the pocket sheet318extend, i.e. the direction away from the spine portion316, when the cover body is opened.

The curved retaining portion350is connected adjacent to the inner side of a hinge portion on the front cover side360and the inner side of a hinge portion on the back cover side362and spaced from the group of the pocket sheets330such that the curved retaining portion350enables the end edge of the group of pocket sheet330connected to the cover to curve with a width that is less than the width of the spine portion316of the cover body.

The curved retaining portion350preferably includes a connecting portion on the front cover side352provided adjacent to the side of the front cover portion312, a connecting portion on the back cover side354provided adjacent to the side of the back cover portion314and an interjacent connecting portion356interposed between the connecting portion on the front cover side352and the connecting portion on the back cover portion354. The interjacent connecting portion356is connected to the end edge of the group of pocket sheets330connected to the cover and is configured to curve away from the spine portion316along with the end edge of the group of the pocket sheets330connected to the cover by the tension of the connecting portion on the front cover side352and the connecting portion on the back cover side354when the cover is opened.

The curved retaining portion350is relatively flexible and is configured to arch away from the spine portion316by the weight of the pocket sheet318being in a spread state.

The front cover portion312and the connecting portion on the front cover side352are preferably defined by a unified flat plate, and the back cover portion314and the connecting portion on the back cover side354are also defined by a unified flat plate.

The curved retaining portion350is preferably made of a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, in a square planar shape and includes a through hole358in the region connected to the binding body and is configured so as to curve.

The curved retaining portion350includes a plurality of rectangular planar shaped through holes358which are spaced from one another so as to provide flexibility thereto. In this preferred embodiment, 6 through holes are preferably provided in the curved retaining portion350, an upper through hole358a, a lower through hole358b, and middle through holes358c1,358c2,358c3and358c4.

In this preferred embodiment, in the interjacent connecting portion356, bridge portions356aand356bextend between the connecting portion on the front cover side352and the connecting portion on the back cover side354at the upper edge and the lower edge, respectively. Bridge portions356c1,356c2and356c3extend between the middle through holes358c1and358c3and a bridge portion356c4extend between the middle through hole358c3and the lower through hole358b. Therefore, the adhesion region of the group of pocket sheets330and the interjacent connecting portion356is provided.

Further, preferably a longitudinal bridge portion356eis provided between a hinge portion on the front cover side360and the upper through hole358a, the lower through hole358band the middle through holes358c1,358c2and358c3, and a longitudinal bridge portion356fis provided between a hinge portion on the back cover side362and the upper through hole358a, the lower through hole358band the middle through holes358c1,358c2and358c3.

The longitudinal bridge portion356eand the longitudinal bridge portion356fare arranged to cross from the top edge to the bottom edge of the cover body.

On the curved retaining portion350, the hinge portion on the front cover side360provided between the connecting portion on the front cover side352and the interjacent connecting portion356and the hinge portion on the back cover side362provided between the connecting portion on the back cover side354and the interjacent connecting portion356are parallel or substantially parallel to each other.

The distance between the spine portion316and the front folding portion324of the front cover portion312and the back folding portion326of the back cover portion314, respectively, is set to be substantially equal to or less than the distance between the hinge portion on the front cover side360of the curved retaining portion350and the inner surface of the front cover portion312and the hinge portion on the back cover side362and the inner surface of the back cover portion314. The hinge portion in the front cover side360and the hinge portion on the back cover side362are arranged to be positioned adjacent to the end edge of the spine portion316when the cover body is closed.

The interjacent connecting portion356between the hinge portion on the front cover side360and the hinge portion on the back cover side362is configured to curve away from the spine portion316when the front cover portion312is opened and the width between the hinge portion on the front cover side360and the hinge portion on the back cover side362is preferably less than the width of the spine portion316.

The longitudinal bridge portion356eand the connecting portion on the front cover side352providing the hinge portion on the front cover side360therebetween intersect at substantial right angles in order to retain the shape when a load is not applied and the longitudinal bridge portion356fand the connecting portion on the back cover side354providing the hinge portion on the back cover side362therebetween intersect at substantially right angles in order to retain the shape when a load is not applied. When the connecting portion on the front cover side352side or the connecting portion on the back cover side354side opens corresponding to when the front cover portion312or the back cover portion314is opened, a degree of the angle between the longitudinal bridge portion356eand the connecting portion on the front cover side352expands, and the angle between the longitudinal bridge portion356fand the connecting portion on the back cover side354expands. When the expansion of those angles is about 120 to 130 degrees, and the curved retaining portion350is lifted in the direction away from the spine portion316due to the elasticity of the material of the curved retaining portion350and the elasticity adjacent to the both ends of the hinge portion on the front cover side360and the hinge portion on the back cover side362of the both sides (seeFIG. 47B).

The front cover portion312and the back cover portion314, as shown inFIGS. 36 through 40, define a curved subsidiary portion which fixes the back of the binding body in a desired configuration in a region on a front cover side and a region on a back cover side of the spine portion316between the front cover portion312and the back cover portion314. In this preferred embodiment, the curved subsidiary portion is preferably an independent curved subsidiary member328.

The curved subsidiary member328is preferably made of a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, in a square planar shape. The front folding portion324and the back folding portion326extending from the upper edge to the lower edge are successively provided and the curved subsidiary portion328is provided in the region from the front folding portion324on the front cover portion312to the spine portion316, the region from the back folding portion326on the back cover portion314to the spine portion316, and the spine portion316.

In the curved subsidiary member328, the connecting portion on the front cover side352including the front folding portion324as an axis moves upwardly in the region on the spine portion316on the front cover side extending between the front cover portion312and the back cover portion314, and the connecting portion on the back cover side354including the back folding portion326as an axis moves upwardly, and the curved subsidiary portion328defines the curved subsidiary portion which enables the curved retaining portion350to arch upwardly, i.e. in the direction away from the spine portion316, when the front cover portion312and the back cover portion314are substantially horizontal and parallel to the curved subsidiary member328of the horizontal spine portion316.

On the front cover portion312and the back cover portion314, the front folding portion324and the back folding portion326are parallel or substantially parallel to the front adjacently providing portion320and the back adjacently providing portion322in the direction of their heights crossing from the top edge to the bottom edge thereof adjacent to the front adjacently providing portion320and the back adjacently providing portion322.

The length of the inner face of the spine portion316and the front folding portion324and the length of the inner face of the spine portion316and the back folding portion326are substantially equal (shown inFIG. 38).

A square shape retaining portion323is provided between the front adjacently providing portion320on the side of the front adjacently providing portion320of the spine portion316and a square shape retaining portion323is provided between the back adjacently providing portion322on the side of the back adjacently providing portion322.

A square shape fastening portion on the front cover side325is provided between the front folding portion324on the side of the front folding portion324of the shape retaining portion321and a square shape fastening portion on the back cover side327is provided between the back folding portion326on the side of the back folding portion326.

The curved subsidiary member328preferably has an angular structure and defines a grip portion such that the user can set the spine portion316on his palm, grip the curved subsidiary portion328with his fingers and open the pocket sheet318.

On the front cover portion312and the back cover portion314, a recess for searching370is provided on the free end edge side opposite to the spine portion316, i.e. the left side end edge of the front cover portion312and the right side end edge of the back cover portion314, in the approximate middle of the direction of the height thereof.

The outer end edge of the recess for searching370and the outer end edge332of the pocket sheet318are preferably substantially aligned. Accordingly, with one hand, folding the file310with the cover closed, especially gripping the curved subsidiary portion328and placing the other hand on the recess for search370enables flipping of the front cover portion312or the back cover portion314and the pocket sheet318.

The file310can be flipped from the pocket sheet318positioned on the upper side to the pocket sheet positioned on the lower side with the user's fingers placed on the outermost portion of the outer end edge332of the pocket sheet318and slightly bending the front cover portion312or the back cover portion314in the recess for searching370as shown inFIG. 20.

On the front cover portion312and the back cover portion314, a pair of projection portions372on the upper side and the lower side is preferably provided to cover the index i on the pocket sheet318such that the projection portion372projects toward the outer side of the outer end edge332, of the pocket sheet318on the outside of the region that the recess portion for searching370is provided.

The end edge of the group of pocket sheet330connected to the spine portion316when the cover body is opened is configured to curve away from the spine portion316.

The pocket sheet318includes pockets combined with thermoplastic resin sheets, each pocket sheet318is hot-adhered to another on the end edge connected to the cover thereof, and the end edge connected to the spine portion316is configured to curve inwardly when the pocket sheet318is opened.

The hinge portion on the front cover side360is positioned inwardly of the front folding portion324and the hinge portion on the back cover side362is positioned inwardly of back adjacently providing portion322such that the width (T2) between the hinge portion on the front cover side360and the hinge portion on the back cover side362is than the width (T1) between the front adjacently providing portion320and the back adjacently providing portion322when the cover body is opened, i.e. when the connecting portion on the front cover side352and the connecting portion on the back cover side354are adjacent to one another in the horizontal plane in a flat state and the front cover portion312and the back cover portion314are adjacent to one another the horizontal plane in the flat state.

Additionally, although the width (T1) between the front adjacently providing portion320and the back adjacently providing portion322and the width (T3) between the hinge portion on the front cover side360and the hinge portion on the back cover side362are substantially equal, (T3) is less than (1) by the thickness of the front adjacently providing portion320and the back adjacently providing portion322, since the hinge portion on the front cover side360and the hinge portion on the back cover side362is fastened to the inner surface of the front adjacently providing portion320and the back adjacently providing portion322when the cover body is closed, i.e. when the front cover portion312and the back cover portion314are substantially parallel and the connecting portion on the front cover side352and the connecting portion on the back cover portion354are substantially parallel.

Next, a method of manufacturing the file310shown inFIG. 35of the present invention will be described below with referring toFIGS. 41 through 46.

First, a plurality of pocket sheets318are superimposed, and the edge faces of the inner end edge338that face one another are heated. Consequently, the region which is slightly inward from the inner end edge338is melted. To apply hot welding to the inner end edge338of the pocket sheet318, a hot plate is pressed to the inner end edge338, the vicinity of the inner end edge338is welded and the edge faces of the inner end edge338facing one another are adhered to form the group of pocket sheets330. Adhesion and welding may be performed with a hot-melt adhesive agent or by ultrasonic horn respectively.

The group of pocket sheets330preferably includes pockets combined with thermoplastic resin sheets, each binding sheet is hot adhered to another on the end edge connected to the cover thereof, and the end edge connected to the cover is formed to curve inwardly when the pocket sheet318is opened.

Next, a method for fixing the group of pocket sheets33to the curved retaining portion350of the cover body will be described with referring toFIGS. 43 through 49.

First, a synthetic resin sheet body, such as polypropylene or other suitable material is prepared, Thompson processing is applied thereto, and the cover material380is removed, which will define the cover of the file to form a cover material380having a combined size of the front cover portion312, the back cover portion314, and the curved retaining portion350(Cover material molding step).

For forming the curved retaining portion350with the cover material380made of a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, in a square planar shape, the curved retaining portion350is formed by demarcating the interjacent connecting portion356interposed between the connecting portion on the front cover side352connected to the front cover portion312and the connecting portion on the back cover side354connected to the back cover portion314from the cover material380.

The interjacent connecting portion356is connected to the end edge connected to the cover of the binding body and is formed to curve away from the spine portion316along with the end edge connected to the cover of the group of the pocket sheets330by the tension of the connecting portion on the front cover portion352and the connecting portion on the back cover portion354when the cover is opened.

The curved retaining portion350is preferably made of a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, in a square planar shape and includes the through hole358provided in the region connected to the group of pocket sheets330and is formed so as to curve. The group of pocket sheets330is adhered to the inner surface of the bridge portions356a,356b,356c1,356c2,356c3and356c4of the curved retaining portion350and also to the inner surface of the longitudinal bridge portion356eand356fwith a small space between the hinge portion on the front cover side360and the hinge portion on the back cover side362.

The group of pocket sheets330is attached by hot welding to the upper surface of the interjacent connecting portion356.

The curved retaining portion350is formed by the hinge portion on the front cover side360and the hinge portion on the back cover side362between the connecting portion on the front cover side352and the interjacent connecting portion356and between the connecting portion on the back cover side354and the interjacent connecting portion356.

The distance between the spine portion316and the front folding portion324of the front cover portion312and the back folding portion326of the back cover portion314respectively is preferably substantially equal to or less than the distance between the hinge portion on the front cover side360of the curved retaining portion350and the inner surface of the front cover portion312or the hinge portion on the back cover side362and the inner surface of the back cover portion314. The hinge portion on the front cover side360and the hinge portion on the back cover side362are positioned adjacent to the end edge of the spine portion316in cross direction when the cover is closed.

In this preferred embodiment, a cover material180which is originally a flat plate is applied in a folding process. The longitudinal bridge portion356eand the connecting portion on the front cover side352providing the hinge portion on the front cover side360therebetween intersect at substantially right angles to retain the shape when a load is not applied and the longitudinal bridge portion356fand the connecting portion on the back cover side354providing the hinge portion on the back cover side362therebetween intersect at substantially right angles to retain the shape when a load is not applied.

A molding process is performed by folding the connecting portion on the front cover side352including the hinge portion on the front cover side360therebetween until it is substantially at a right angle to the interjacent connecting portion356and by folding the connecting portion on the back cover side354including the hinge portion on the back cover side362therebetween until it is substantially at a right angle to the interjacent connecting portion356.

When the connecting portion on the front cover side352side or the connecting portion on the back cover side354side opens corresponding to when the front cover portion312or the back cover portion314is opened, the degree of the angle between the longitudinal bridge portion356eand the connecting portion on the front cover side352expands, and the angle between the longitudinal bridge portion356fand the connecting portion on the back cover side354expands. When the expansion of those angles become about 120 to 130 degrees, and the curved retaining portion150is lifted toward the direction away from the spine portion316with the elasticity of the material comprising the curved retaining portion350and the elasticity adjacent to the both ends of the hinge portion on the front cover side360and the hinge portion on the back cover side362of the both sides.

The interjacent connecting portion356between the hinge portion on the front cover side360and the hinge portion on the back cover side362is formed to curve away from the spine portion316when the cover portion312is opened and the width of the interjacent connecting portion356is less than the width of the spine portion316.

Next, a method for adhering the group of pocket sheets330to a cover material380will be described.

The curved retaining portion350is connected adjacent to the hinge portion on the front cover side360of the front cover portion312and the hinge portion on the back cover side362of the back cover portion314so as to be spaced from the group of the pocket sheets330such that the curved retaining portion350enables the end edge connected to the cover of the group of pocket sheet330to curve with a width that is less than the width of the spine portion316of the cover body.

The curved retaining portion350is welded to the connecting portion on the front cover side352connected to the side of the front cover portion312and the outer surface of the front cover portion312and to the connecting portion on the back cover side354on the side of the back cover portion314and the outer surface of the back cover portion314and extends between the front cover portion312and the back cover portion314.

The curved retaining portion350includes the connecting portion on the front cover side352connected to the side of the front cover portion312, the connecting portion on the back cover side354connected to the side of the back cover portion314and the interjacent connecting portion356interposed between the connecting portion on the front cover side352and the connecting portion on the back cover portion354. The interjacent connecting portion356is connected to the end edge of the binding body connected to the cover and is configured to curve away from the spine portion316along with the end edge connected to the cover of the binding body by the tension of the connecting portion on the front cover portion352as the rigid body and the connecting portion on the back cover portion354as the rigid body when the cover body is opened.

The hinge portion on the front cover side360and the hinge portion on the back cover side362are provided between the connecting portion on the front cover side352and the interjacent connecting portion356and between the connection portion on the back cover side354and the interjacent connecting portion356.

Next, for forming the curved subsidiary portion328, a thermoplastic synthetic resin sheet is prepared, Thompson processing is applied thereto, and the curved subsidiary portion328is punched out in a square planar shape.

Further, a spine index paper Z is pasted to the surface of the spine area using an adhesive agent, which will later become the spine portion316(Spine index paper pasting step).

For example, as shown inFIGS. 48 and 49, when a thermoplastic resin sheet is used as the curved subsidiary member328, the heat-press molding is applied with the V-shape heater (not shown) to the V-shape slots320A,322A,324A and326A which have a substantially V-shape section and are parallel or substantially parallel to one another in order to form the front adjacently providing portion320, the back adjacently providing portion322, the front folding portion324, and the back folding portion326. Then, the cover material380is formed so as to be foldable (V-shape slot molding step).

Next, the longitudinal bridge portion356eand the connecting portion on the front cover side352provided with the hinge portion on the front cover side360therebetween are formed to intersect at substantially right angles to retain the shape and the retaining portion321and the retaining portion323of the curved subsidiary portion328formed to retain the shape by intersecting with the spine portion316in a state in which the longitudinal bridge portion356fand the connecting portion on the back cover side354provided with the hinge portion on the back cover side362therebetween intersect at substantially right angles to retain the shape. Then, a fastening portion on the front cover side325, the connecting portion on the front cover side352, a fastening portion on a back cover side327, and the connecting portion on the back cover side354are adhered.

Then, the cover body including the curved subsidiary portion328is formed by fastening the outer end edge of the front cover portion320at the outer surface of the front cover portion312and portions outward from the hinge portion on the front cover side360and fastening the back adjacently providing portion322at the outer surface of the back cover portion314and portions outward from the hinge portion on the back cover side362.

The distance (W1) between the spine portion316and the front folding portion324of the front cover portion312and the back folding portion326of the back cover portion314respectively is substantially equal to the distance (W2) between the hinge portion on the front cover side360of the curved retaining portion350and the inner surface of the front cover portion312or the hinge portion on the back cover side362and the inner surface of the back cover portion314and (W2) is less than (W1) by the thickness of the spine portion316.

The hinge portion on the front cover side360and the hinge portion on the back cover side362are positioned adjacent to the end edge of the spine portion316when the cover body is closed. The hinge portion on the front cover side360and the hinge portion on the back cover side362are formed to curve away from the spine portion316when the cover body is opened and the width between the hinge portion on the front cover side360and the hinge portion on the back cover side362is less than the width of the spine portion316. Accordingly, when the cover body is opened and the group of pocket sheets330is spread, the pocket sheet318is flat.

The present invention is not limited to the preferred embodiments described above, and the invention can be variously modified.

The pocket file shown inFIG. 1can be modified as shown inFIGS. 50 through 52.

A file410preferably includes the curved retaining portion configured to curve the end edge of the group of pocket sheets30in the direction of the pocket sheet18extending at the inner side of the spine portion16provided between the front cover portion12and the back cover portion14when the cover is opened and includes a curved subsidiary portion which fixes the back of the cover body into a desired configuration in a region on a front cover side and a region on a back cover side of the spine portion16between the front cover portion12and the back cover portion14.

As shown inFIGS. 50 through 52, the front folding portion24and the back folding portion26extending from the top edge to the bottom edge are provided adjacent to the front connecting portion20and the back connecting portion22of the front cover portion12, the back cover portion14and the spine portion16, and the grip portion28is preferably provided in the region from the front folding portion24on the front cover portion12to the spine portion16, the region from the back folding portion26on the back cover portion14to the spine portion16and the spine portion16.

In grip portion28, the connecting portion on a front cover side452including the front folding portion24as an axis moves upwardly in the region on the spine portion16on the front cover side between the front cover portion12and the back cover portion14, and the connecting portion on a back cover side454including the back folding portion26as an axis moves upwardly and the grip portion28defines the curved subsidiary portion which enables a connecting portion450as a curved subsidiary portion to arch upwardly, i.e. in the direction away from the spine portion16, when the front cover portion12and the back cover portion14are substantially horizontal, and the grip portion28is parallel or substantially parallel to the horizontal spine portion16.

On the front cover portion12and the back cover portion14, the front folding portion24and the back folding portion26are parallel or substantially parallel to the front adjacently providing portion20and the back adjacently providing portion22in the direction of their heights extending from the top edge to the bottom edge thereof adjacent to the front adjacently providing portion20and the back adjacently providing portion22.

The length of the inner face of the spine portion16and the front folding portion24and the length of the inner face of the spine portion16and the back folding portion26are preferably substantially equal (shown inFIG. 52).

The mount42is arranged such that the front folding portion24and the back folding portion26are not adjacent to the mount42.

The group of pocket sheets30is connected by the end edge connected thereto and the connecting portion450connecting the front cover portion12and the back cover portion14.

The connecting body450is preferably a substantially square rigid plate body when viewed in a planar view made of thermoplastic synthetic resin and includes the curved retaining portion which curves the group of pocket sheets30, that is welded and connected at the connecting end edge of the group of pocket sheets30as the binding body, toward the direction in which the pocket sheet18extends.

The connecting body450is connected adjacent to the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14and is spaced from the group of the pocket sheets30such that the connecting body450enables the end edge connected to the cover of the group of pocket sheet30to curve with the width less than the width of the spine portion16of the cover body.

The connecting body450includes a connecting portion on the front cover side452connected to the side of the front cover portion12, a connecting portion on the back cover side454connected to the side of the back cover portion14, and an interjacent connecting portion456interposed between the connecting portion on the front cover side452and the connecting portion on the back cover side454. The interjacent connecting portion456is connected to the end edge connected to the cover of the group of pocket sheets30and is configured to curve away from the spine portion16along with the end edge connected to the cover of the group of the pocket sheets30by the tension of the connecting portion on the front cover side452and the connecting portion on the back cover side454when the cover is opened.

The interjacent connecting portion456is relatively flexible and is configured to curve toward the side the pocket sheet18as the binding sheet extends, i.e. away from the spine portion16, by the weight of the pocket sheet18being in a spread state.

The interjacent connecting portion456of the connecting body450includes a hinge slot458in the region connected to the binding body and is configured so as to curve.

The interjacent connecting portion456of the connecting body450includes a plurality of the hinge slots458on the side of the spine portion16which are spaced from one another so as to provide flexibility thereto. In this preferred embodiment, 3 narrow slots are provided, a front hinge slot458a, a back hinge slot458b, and a middle hinge slot458c.

The connecting body450includes the spaced apart substantially parallel hinge slots458which extend from the top edge to the bottom edge to provide flexibility and is configured to curve away from the back cover portion16when the pocket sheet18is opened. It differs from the preferred embodiment shown inFIG. 1in this respect.

On the connecting body450, the hinge portion on the front cover side60provided between the connecting portion on the front cover side452and the interjacent connecting portion456and the hinge portion on the back cover side62provided between the connecting portion on the back cover side454and the interjacent connecting portion456are preferably parallel or substantially parallel to each other.

On the interjacent connecting portion456, a longitudinal bridge portion456eis successively provided adjacent to the hinge portion on the front cover side60so as to extend from the top edge to the bottom edge of the interjacent connecting portion456and a longitudinal bridge portion456fis successively provided adjacent to the hinge portion on the back cover side62so as to extend from the top edge to the bottom edge of the interjacent portion456.

The distance between the spine portion16and the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14respectively is preferably substantially equal or less than the distance between the hinge portion on the front cover side60of the connecting body450and the inner surface of the front cover portion12and between the hinge portion on the back cover side62or the inner surface of the back cover portion14. The hinge portion in the front cover side60and the hinge portion on the back cover side62are positioned adjacent to the end edge of the spine portion16when the cover is closed.

The interjacent connecting portion456interposed between the hinge portion on the front cover side60and the hinge portion on the back cover side62is configured to curve away from the spine portion16and the width between the hinge portion on the front cover side60and the hinge portion on the back cover side62is preferably less than the width of the spine portion16when the front cover portion12is opened.

The pocket file shown inFIG. 21can be modified as shown inFIGS. 53through55.

A file510preferably includes a curved subsidiary portion which fixes the back of the cover body in a desired shape in regions on a front cover side and on a back cover side of the spine portion116between the front cover portion112and the back cover portion114and the curved retaining portion configured to curve the end edge of the group of pocket sheets130toward the direction of the pocket sheet118as the binding sheet extend at the inner side of the spine portion116provided between the front cover portion112and the back cover portion114when the cover is opened.

In this modified example, the curved subsidiary portion is preferably an independent curved subsidiary member128that is substantially equivalent to the pocket file shown inFIG. 21.

A curved retaining portion550is connected adjacent to the outer side of the hinge portion on the front cover side160and the outer side of the hinge portion on the back cover side162and is spaced from the group of the pocket sheets130in such that the curved retaining portion550enables the end edge connected to the cover of the group of pocket sheet130to curve with the width less than the width of the spine portion116of the cover body.

The curved retaining portion550preferably includes the connecting portion on a front cover side552provided on the side of the front cover portion112, the connecting portion on a back cover side554provided on the side of the back cover portion114, and an interjacent connecting portion556interposed between the connecting portion on the front cover side552and the connecting portion on the back cover portion554. The interjacent connecting portion556is connected to the end edge of the group of pocket sheets130connected to the cover and is configured to curve away from the spine portion116along with the end edge connected to the cover of the group of the pocket sheets130by the tension of the connecting portion on the front cover side552and the connecting portion on the back cover side554when the cover is opened.

The curved retaining portion550is relatively flexible and is configured to arch toward the side of the pocket sheet118as the binding sheet extends, i.e. away from the spine portion116, by the weight of the pocket sheet118being in a spread state.

The interjacent connecting portion556of the curved retaining portion550is preferably made of a thermoplastic synthetic resin sheet body, such as polypropylene or other suitable material, for example, in a substantially square planar shape and includes a hinge slot558in the region connected to the group of pocket sheets130and is configured so as to curve.

The interjacent connecting portion556of the curved retaining portion550preferably includes a plurality of the hinge slots558on the side of the spine portion116which are spaced from one another so as to provide flexibility thereto. In this preferred embodiment, 3 narrow slots are provided, a front hinge slot558a, a back hinge slot558b, and a middle hinge slot558c.

The connecting body550includes the substantially parallel spaced hinge slots558extending from the top edge to the bottom edge to provide flexibility and which are arranged to curve toward the opposite side of the back cover portion116when the pocket sheet118is opened. It differs from the preferred embodiment shown inFIG. 2in this respect.

On the curved retaining portion550, the hinge portion on the front cover side160provided between the connecting portion on the front cover side552and the interjacent connecting portion556and the hinge portion on the back cover side162provided between the connecting portion on the back cover side554and the interjacent connecting portion556are preferably parallel or substantially parallel to each other.

On the interjacent connecting portion556, a longitudinal bridge portion556eis provided adjacent to the hinge portion on the front cover side160so as to extend from the top edge to the bottom edge of the interjacent connecting portion556and a longitudinal bridge portion556fis provided adjacent to the hinge portion on the back cover side162so as to extend from the top edge to the bottom edge of the interjacent portion556.

The distance between the spine portion116and the front folding portion124of the front cover portion112and the back folding portion126of the back cover portion114, respectively, is preferably substantially equal to or less than the distance between the hinge portion on the front cover side160of the curved retaining portion550and the inner surface of the front cover portion112and the hinge portion on the back cover side162and the inner surface of the back cover portion114. The hinge portion in the front cover side160and the hinge portion on the back cover side162are arranged to be positioned adjacent to the end edge of the spine portion116when the cover body is closed.

The interjacent connecting portion556between the hinge portion on the front cover side160and the hinge portion on the back cover side162is configured to curve away from the spine portion116when the front cover portion112is opened and the width between the hinge portion on the front cover side160and the hinge portion on the back cover side162is preferably less than the width of the spine portion116.

Further, the pocket file shown inFIG. 1can be modified as shown inFIGS. 56 through 58.

A file610includes a curved retaining portion configured to curve the end edge of the group of pocket sheets30toward the side of the pocket sheet18extending at the inner side of the spine portion16provided between the front cover portion12and the back cover portion14when the cover is opened and also includes a curved subsidiary portion which fixes the back of the cover body in a desired configuration in a region on a front cover side and a region on a back cover side of the spine portion16between the front cover portion12and the back cover portion14.

As shown inFIGS. 56 through 58, the front folding portion24and the back folding portion26extending from the top edge to the bottom edge are provided adjacent to the front connecting portion20and the back connecting portion22of the front cover portion12, the back cover portion14and the spine portion16, and the grip portion28is provided in the region from the front folding portion24on the front cover portion12to the spine portion16, the region from the back folding portion26on the back cover portion14to the spine portion16, and the spine portion16.

In the grip portion28, the connecting portion on a front cover side652including the front folding portion24as an axis moves upwardly in the region on the spine portion16on the front cover side between the front cover portion12and the back cover portion14, and the connecting portion on a back cover side654including the back folding portion26as an axis moves upwardly and the grip portion28defines the curved subsidiary portion which enables a connecting portion650as a curved subsidiary portion to arch toward the direction of the pocket sheet18as the binding sheet extends, i.e. in the direction away from the spine portion16, when the front cover portion12and the back cover portion14are substantially horizontal, and the grip portion28is substantially parallel to the horizontal spine portion16.

On the front cover portion12and the back cover portion14, the front folding portion24and the back folding portion26are parallel or substantially parallel to the front adjacently providing portion20and the back adjacently providing portion22in the direction of their heights from the top edge to the bottom edge thereof adjacent to the front adjacently providing portion20and the back adjacently providing portion22.

The length of the inner face of the spine portion16and the front folding portion24and the length of the inner face of the spine portion16and the back folding portion26are preferably substantially equal (shown inFIG. 57A).

The mount42is arranged such that the front folding portion24and the back folding portion26are not adjacent to the mount42.

The group of pocket sheets30is connected by the end edge connected thereto and the connecting portion650connecting the front cover portion12and the back cover portion14.

The connecting body650is preferably defined by a substantially square rigid plate body when viewed in a planar view made of thermoplastic synthetic resin and includes the curved retaining portion which curves the group of pocket sheets30, which are welded and connected at the connecting end edge of the group of pocket sheets30, toward the direction of the pocket sheet18as the binding body extends.

The connecting body650is connected adjacent to the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14and is spaced from the group of the pocket sheets30such that the connecting body650enables the end edge connected to the cover of the group of pocket sheet30to curve with the width less than the width of the spine portion16of the cover body.

The connecting body650includes the connecting portion on the front cover side652connected to the side of the front cover portion12, the connecting portion on the back cover side654connected to the side of the back cover portion14, and an interjacent connecting portion656interposed between the connecting portion on the front cover side652and the connecting portion on the back cover side654. The interjacent connecting portion656is connected to the end edge connected to the cover of the group of pocket sheets30and is configured to curve away from the spine portion16along with the end edge connected to the cover of the group of the pocket sheets30by the tension of the connecting portion on the front cover side652and the connecting portion on the back cover side654when the cover is opened.

The interjacent connecting portion656of the connecting body650preferably has a thickness less than the connecting portion on the front cover side652and the connecting portion on the back cover side654so that the interjacent connecting portion656has flexibility and is arranged to arch toward the side of the pocket sheet18as the binding sheet extends, i.e. away from the spine portion16, by the weight of the pocket sheet18being in a spread state.

In this preferred embodiment, a plastically deformed region, which includes the connecting body650, including the interjacent connecting portion656made of a synthetic resin sheet body having substantially uniform thickness is formed by hot press. By decreasing the thickness thereof, flexibility is provided.

On the connecting body650, the hinge portion on the front cover side60provided between the connecting portion on the front cover side652and the interjacent connecting portion656and the hinge portion on the back cover side62provided between the connecting portion on the back cover side654and the interjacent connecting portion656are parallel or substantially parallel to each other.

On the interjacent connecting portion656, a longitudinal bridge portion656eis provided adjacent to the hinge portion on the front cover side60so as to extend from the top edge to the bottom edge of the interjacent connecting portion656and a longitudinal bridge portion656fis provided adjacent to the hinge portion on the back cover side62so as to extend from the top edge to the bottom edge of the interjacent portion656.

In this preferred embodiment, the longitudinal bridge portions656eand656fpreferably have substantially the same thickness as the connecting portion on the front cover side652and the connecting portion on the back cover side654and the portion between the longitudinal bridge portions656eand656fpreferably have a decreased thickness as described above.

The distance between the spine portion16and the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14respectively is preferably substantially equal to or less than the distance between the hinge portion on the front cover side60of the connecting body650and the inner surface of the front cover portion12and between the hinge portion on the back cover side62and the inner surface of the back cover portion14. The hinge portion in the front cover side60and the hinge portion on the back cover side62are positioned adjacent to the end edge of the spine portion16when the cover is closed.

The interjacent connecting portion656between the hinge portion on the front cover side60and the hinge portion on the back cover side62is configured to curve away from the spine portion16and the width between the hinge portion on the front cover side60and the hinge portion on the back cover side62is less than the width of the spine portion16when the front cover portion12is opened.

The pocket file shown inFIG. 21can be modified as shown inFIGS. 59 through 61.

A file710includes a curved subsidiary portion which fixes the back of the cover body in a desired configuration in regions on a front cover side and on a back cover side of the spine portion116between the front cover portion112and the back cover portion114and the curved retaining portion arranged to curve the end edge of the group of pocket sheets130toward the direction of the pocket sheet118extending at the inner side of the spine portion116provided between the front cover portion112and the back cover portion114when the cover body is opened. In this modified example, the curved subsidiary portion is preferably an independent curved subsidiary member128that is equivalent to the pocket file shown inFIG. 21.

A curved retaining portion750is connected adjacent to the inner side of the hinge portion on the front cover side160and the inner side of the hinge portion on the back cover side162and is spaced from the group of the pocket sheets130such that the curved retaining portion750enables the end edge connected to the cover of the group of pocket sheet130to curve with the width less than the width of the spine portion116of the cover body.

The curved retaining portion750includes a connecting portion on a front cover side752provided in the side of the front cover portion112, a connecting portion on a back cover side754provided in the side of the back cover portion114, and an interjacent connecting portion756provided between the connecting portion on the front cover side752and the connecting portion on the back cover portion754. The interjacent connecting portion756is connected to the end edge connected to the cover of the group of pocket sheets130and is configured to curve away from the spine portion116along with the end edge connected to the cover of the group of the pocket sheets130by the tension of the connecting portion on the front cover side752and the connecting portion on the back cover side754when the cover is opened.

The curved retaining portion750is relatively flexible and is arranged to arch in a direction away from the spine portion116by the weight of the pocket sheet118being in a spread state.

The curved retaining portion750is made of a thermoplastic synthetic resin sheet body having a substantially square planar shape having a uniform thickness and is configured to curve by decreasing the thickness of the region connected to the group of pocket sheets130so that flexibility is provided.

In this preferred embodiment, a plastically deformed region, which includes the connecting body750, including the interjacent connecting portion756made of a synthetic resin sheet body having a uniform thickness is formed by hot press. By decreasing the thickness thereof, flexibility is improved.

The curved retaining portion750is arranged to arch toward the side of the pocket sheet118as the binding sheet extends, i.e. away from the spine portion116, by the weight of the pocket sheet118being in a spread state.

On the curved retaining portion750, the hinge portion on the front cover side160provided between the connecting portion on the front cover side752and the interjacent connecting portion756and the hinge portion on the back cover side162provided between the connecting portion on the back cover side754and the interjacent connecting portion756are parallel or substantially parallel to each other.

On the interjacent connecting portion756, a longitudinal bridge portion756eis provided adjacent to the hinge portion on the front cover side160so as to extend from the top edge to the bottom edge of the interjacent connecting portion756and a longitudinal bridge portion756fis provided adjacent to the hinge portion on the back cover side162so as to extend from the top edge to the bottom edge of the interjacent portion756.

In this preferred embodiment, the longitudinal bridge portions756eand756fhave the substantially the same thickness as the connecting portion on the front cover side752and the connecting portion on the back cover side754and the portion between the longitudinal bridge portions756eand756fhave a decreased thickness.

The distance between the spine portion116and the front folding portion124of the front cover portion112and the back folding portion26of the back cover portion114, respectively, is preferably substantially equal to or less than the distance between the hinge portion on the front cover side160of the curved retaining portion750and the inner surface of the front cover portion112and between the hinge portion on the back cover side162and the inner surface of the back cover portion114. The hinge portion in the front cover side160and the hinge portion on the back cover side162are positioned adjacent to the end edge of the spine portion116when the cover body is closed.

The interjacent connecting portion756between the hinge portion on the front cover side160and the hinge portion on the back cover side162is configured to curve away from the spine portion116and the width between the hinge portion on the front cover side160and the hinge portion on the back cover side162is less than the width of the spine portion116when the front cover portion112is opened.

The pocket file shown inFIG. 1can be modified as shown inFIGS. 62 through 64.

A file810includes a curved retaining portion configured to curve the end edge of the group of pocket sheets30toward the side of the pocket sheet18extending at the inner side of the spine portion16provided between the front cover portion12and the back cover portion14when the cover is opened and also includes a curved subsidiary portion which fixes the back of the cover body in a desired configuration in a region on a front cover side and a region on a back cover side of the spine portion16between the front cover portion12and the back cover portion14.

As shown inFIGS. 62 through 64, the front folding portion24and the back folding portion26extending from the top edge to the bottom edge are arranged adjacent to the front connecting portion20and the back connecting portion22of the front cover portion12, the back cover portion14and the spine portion16, and the grip portion28is provided in the region from the front folding portion24on the front cover portion12to the spine portion16, the region from the back folding portion26on the back cover portion14to the spine portion16, and the spine portion16.

In the grip portion28, the connecting portion on a front cover side852including the front folding portion24as an axis moves upwardly in the region on the spine portion16on the front cover side between the front cover portion12and the back cover portion14, and the connecting portion on a back cover side854including the back folding portion26as an axis moves upwardly and the grip portion28defines the curved subsidiary portion which enables a connecting portion850as a curved subsidiary portion to arch toward the direction of the pocket sheet18as the binding sheet extends, i.e. in the direction away from the spine portion16, when the front cover portion12and the back cover portion14is substantially horizontal, and the grip portion28is substantially parallel to the horizontal spine portion16.

On the front cover portion12and the back cover portion14, the front folding portion24and the back folding portion26are parallel or substantially parallel to the front adjacently providing portion20and the back adjacently providing portion22in the direction of their heights from the top edge to the bottom edge thereof adjacent to the front adjacently providing portion20and the back adjacently providing portion22.

The length of the inner surface of the spine portion16and the front folding portion24and the length of the inner surface of the spine portion16and the back folding portion26are preferably substantially equal (shown inFIG. 63).

The mount42is arranged such that the front folding portion24and the back folding portion26are not adjacent to the mount42.

The group of pocket sheets30is connected by the end edge connected thereto and the connecting portion850connecting the front cover portion12and the back cover portion14.

The connecting body850is defined by a substantially square rigid plate body when in a planar view made of thermoplastic synthetic resin and includes the curved retaining portion which curves the group of pocket sheets30, which are welded and connected at the connecting end edge of the group of pocket sheets30, toward the direction of the pocket sheet18as the binding body extends.

The connecting body850is connected adjacent to the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14and is spaced from the group of the pocket sheets30such that the connecting body650enables the end edge connected to the cover of the group of pocket sheet30to curve with the width less than the width of the spine portion16of the cover body.

The connecting body850includes the connecting portion on the front cover side852connected to the side of the front cover portion12, the connecting portion on the back cover side854connected to the side of the back cover portion14, and an interjacent connecting portion856interposed between the connecting portion on the front cover side852and the connecting portion on the back cover side854. The interjacent connecting portion856is connected to the end edge connected to the cover of the group of pocket sheets30and is configured to curve away from the spine portion16along with the end edge connected to the cover of the group of the pocket sheets30by the tension of the connecting portion on the front cover side852and the connecting portion on the back cover side854when the cover is opened.

The interjacent connecting portion856is relatively flexible and is arranged to arch toward the side of the pocket sheet18as the binding sheet extends, i.e. away from the spine portion16, by the weight of the pocket sheet18being in a spread state.

The connecting body850includes a through hole858in the region connected to the binding body and is configured so as to curve.

The connecting body850includes a plurality of the rectangular planar shaped through holes858which are spaced from one another so as to provide flexibility thereto. In this preferred embodiment, 5 through holes are provided, an upper through hole858a, a lower through hole858b, middle through holes858c1,858c2and858c3.

In this preferred embodiment, in the interjacent connecting portion856, bridge portions856aand856bextend between the connecting portion on the front cover side852and the connecting portion on the back cover side854at the upper edge and the lower edge, respectively. A bridge portion856c1is provided between the upper through hole858aand the middle through hole858c1and a bridge portion856c4is provided between the middle through hole858c3and the lower through hole858band the bridge portion856c4is crosslinked in between the middle through hole858c3and the lower through hole858b. Therefore, the adhesion region of the interjacent connecting portion856and the group of pocket sheets30is provided.

Further, a longitudinal bridge portion856eis provided between the hinge portion on the front cover side60and the upper through hole858a, the lower through hole858band the middle through holes858c1,858c2and858c3, and a longitudinal bridge portion856fis provided between the hinge portion on the back cover side62and the upper through hole858a, the lower through hole858band the middle through holes858c1,858c2and858c3.

On the connecting body850, the hinge portion on the front cover side60provided between the connecting portion on the front cover side852and the interjacent connecting portion856and the hinge portion on the back cover side62provided between the connecting portion on the back cover side854and the interjacent connecting portion856are preferably parallel or substantially parallel to each other.

The distance between the spine portion16and the front folding portion24of the front cover portion12and the back folding portion26of the back cover portion14respectively is preferably substantially equal to or less than the distance between the hinge portion on the front cover side60of the connecting body850and the inner surface of the front cover portion12and between the hinge portion on the back cover side62and the inner surface of the back cover portion14. The hinge portion in the front cover side60and the hinge portion on the back cover side62are positioned adjacent to the end edge of the spine portion16when the cover is closed.

The interjacent connecting portion856between the hinge portion on the front cover side60and the hinge portion on the back cover side62is configured to curve away from the spine portion16when the front cover portion12is opened and the width between the hinge portion on the front cover side60and the hinge portion on the back cover side62is preferably less than the width of the spine portion16.

The connecting portion on the front cover side852and the interjacent connecting portion856providing the hinge portion on the front cover side60therebetween intersect at substantially right angles to retain the shape when a load is not applied and the connecting portion on the back cover side854and the interjacent connecting portion856providing the hinge portion on the back cover side62therebetween intersect at substantially right angles to retain the shape when a load is not applied. When the connecting portion on the front cover side852side or the connecting portion on the back cover side854side opens corresponding to when the front cover portion12or the back cover portion14is opened, a degree of the angle between the interjacent connecting portion856and the connecting portion on the front cover side852expands, and the angle between the interjacent connecting portion856and the connecting portion on the back cover side854expands. When the expansion of those angles is about 120 to 130 degrees, and the connecting portion850is lifted in the direction away from the spine portion16with the elasticity of the material used for the connecting portion850and the elasticity adjacent to the both ends of the hinge portion on the front cover side60and the hinge portion on the back cover side62of the both sides.