Articulated hinge device and electronic device using the same

An articulated hinge that can hold a folded part of a flexible display sheet that deforms following the opening and closing of the first and second casings, and an electronic gear using this articulated hinge, an articulated hinge couples the first and second casings of an electronic gear in a foldable manner by a relative folding motion between the open and closed positions where an articulated hinge is arranged on the back side of a flexible display sheet attached over the inner surfaces of both the first and the second casings is disclosed. The articulated hinge has a frame portion, wherein an odd number (1+2n, where n is an integer greater than or equal to 2) of vertical frames are arranged in parallel along a width direction, where its shorter-side direction is the width direction and its vertical direction is a vertical direction.

FIELD OF THE INVENTION

The invention relates to an articulated hinge device suitably used in an electronic device, such as foldable mobile phone, electronic notebook, PDA, netbook and notebook PC, which is built by attaching a flexible display sheet made e.g. of organic EL over respective surfaces of a first casing and a second casing, wherein organic light emitting diodes (OLEDs) are used as light emitting diodes of a bendable display member; it further relates to an electronic device using such an articulated hinge device.

BACKGROUND ART

Recently, an electronic device, such as mobile phone, which is built by attaching a single flexible display sheet made of organic EL over respective surfaces of a first and a second casings has been developed and is establishing its presence step by step. As a hinge device coupling a first casing and a second casing of such an electronic device, such that these casings are openable and closable relative to each other, a multiaxial hinge device using a plurality of hinge pins is known in JP Laid-Open Patent Application No. 2020-125841. This multiaxial hinge device enables the first and second casings to be opened and closed with no change in surface length of the flexible display sheet. Still further, it is designed such that a bent part keeps a constant radius of curvature in a space part inside the multiaxial hinge device in order to prevent a flexible display sheet from snapping or causing failure when the first casing and the second casing are opened and closed.

By the way, in a conventional multiaxial hinge device, when a first casing and a second casing are opened and closed and a bent part of the flexible display sheet is deformed from a flat state to a curved and folded state, the folded part is deformed within a space of the multiaxial hinge device. Therefore, the folded part is not always held in a stable state, and the folded part of the flexible display sheet may shift within the space that accommodates the folded part of the flexible display sheet in the multiaxial hinge device.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an articulated hinge device that can always hold a bent part of a flexible display sheet that deforms following the opening and closing of the first and second casings, and an electronic device using this articulated hinge device.

In order to solve the above problem, an articulated hinge device of the first invention couples a first casing and a second casing of an electronic device in a foldable manner by a relative folding motion between an opened position and a closed position, wherein the articulated hinge device is arranged on the back side of a flexible display sheet attached over the inner surfaces of both the first casing and the second casing, wherein the articulated hinge device comprises a frame portion, wherein an odd number (1+2n, where n is an integer greater than or equal to 2) of vertical frames are arranged in parallel along a width direction, wherein its shorter-side direction is the width direction and its longitudinal direction is a vertical direction; a first base frame arranged in parallel with the vertical frame at one end of the frame portion in the width direction and attached to the first casing; a second base frame arranged in parallel with the vertical frame at the other end of the frame portion in the width direction and attached to the second casing; articulated portions comprising articulation joints respectively arranged between adjacent frames for rotatably displacing the adjacent frames along a predetermined trajectory, while changing directions and angles of their respective rotation in a frame row composed of the first base frame and the second base frame, wherein the both base frames are parallel to each other on both sides in the width direction of the odd number of vertical frames; a synchronous driving portion for coupling the adjacent frames in the frame row in series by gears and for synchronously displacing each of the adjacent frames in the direction away from each other when the second base frame and the second base frame shift relative to each other in a direction toward the closed position, and synchronously displacing each of the adjacent frames in the direction in which the both approach each other when the second base frame and the second base frame shift relative to each other in the opening direction; and a stop holding portion for stopping the first base frame in its rotation movement relative to the vertical frame adjacent to the first base frame, as well as the second base frame in its rotation movement relative to the vertical frame adjacent to the second base frame, and for holding them between the closed position and the opened position.

An articulated hinge device of the second invention is an articulated hinge device of the first invention, wherein articulation joints can be composed of an arc-shaped arm provided on one adjacent frame with a guide surface being a predetermined curved surface and of guide holes provided on other adjacent frame in the frame for sliding relative to the one adjacent frame along the guide surface of the arc-shaped arm to be engaged with the adjacent frame.

An articulated hinge device of the third invention is an articulated hinge device of the first or second invention, wherein one or more groups of frames is/are arranged in a bilaterally symmetrical manner, wherein one group is made up with the second and third vertical frames installed side by side on both sides in order from the first vertical frame side, and that two articulated portions can be provided at both ends of the frame section in the vertical direction, or at three articulated portions at both ends and the center of the frame section in the vertical direction.

An articulated hinge device of the fourth invention is an articulated hinge device of the third invention, wherein articulation joints of articulated portions comprise articulation joints on the left side in the width direction respectively provided between the first vertical frame and the first base frame, and articulation joints on the right side in the width direction respectively provided between the first vertical frame and the second base frame, wherein articulation joints on the left side in the width direction can be configured to ensure that the arc-shaped arms respectively project from the first vertical frame, the second and third vertical frames toward the first base frame side, and guide hole portions are each provided on the second and third vertical frames and the first base frame corresponding to each arc-shaped arm, and the articulation joints on the right side of the width direction can be configured to ensure that arc-shaped arms protrude respectively from the first vertical frame, the second and the third vertical frame toward the second base frame side, and guide hole portions are each provided on the second vertical frame, the third vertical frame and the second base frame corresponding to each arc-shaped arm.

An articulated hinge device of the fifth invention is an articulated hinge device of one of the first to third inventions, wherein the synchronous driving portion can be configured to ensure that a plurality of synchronous gear trains are provided along the width direction, wherein three consecutive frames in parallel are coupled as one group by gears in series, and synchronous gear trains adjacent along the width direction share the two adjacent frames close to the adjacent synchronous gear train among the three which make up one group.

An articulated hinge device of the sixth invention is an articulated hinge device of the fifth invention, wherein the synchronous gear train can be configured to ensure that a meshing position of a first arc-shaped arm with a left synchronous gear and a meshing position of a right synchronous gear with a second arc-shaped arm shift from the root to the tip side during the folding motion from the open to the closed position and from the tip portion side to the base portion side during the folding motion from the closed position to the opened position.

An articulated hinge device of the seventh invention is an articulated hinge device of the third invention, wherein it can be configured to ensure that an insertion hole into which a tip of an arc-shaped arm penetrating through a guide hole portion provided on the second vertical frame adjacent to the first vertical frame side is inserted provided on the third vertical frame, and insertion holes into which tips of arc-shaped arms penetrating through a guide hole portion provided on the third vertical frame adjacent to the first vertical frame side are inserted are provided on the first and second base frames.

An articulated hinge device of the eighth invention is an articulated hinge device of one of the first to seventh inventions, wherein the articulated hinge device can be configured to ensure that a plurality of articulation joints provided between the first vertical frame and the first base frame are arranged with articulation joints adjacent to each other in the width direction being displaced from each other in the vertical direction, and a plurality of articulation joints provided between the first vertical frame and the second base frame are arranged with articulation joints adjacent to each other in the width direction being displaced from each other in the vertical direction.

An articulated hinge device of the ninth invention is an articulated hinge device of the first invention, wherein the articulated hinge device can be configured to ensure that the stop holding portion comprises a first friction click stop mechanism provided on the first base frame having a first input gear, a second friction click stop mechanism provided on the second base frame having a second input gear, a first coupling gear fixed to a vertical frame adjacent to a second base frame and meshed with the first input gear, and a second coupling gear fixed to a vertical frame adjacent to a second base frame and meshed with the second input gear, and wherein the first and second friction click stop mechanisms comprise a cam portion having a corrugated portion, wherein click bodies respectively fixed to the rotary shafts of the first and second input gear rotate integrally with each of the rotary shafts and click-engage at the open and closed positions, and a friction force generating portion for giving a friction force on the rotation of the rotary shaft.

An articulated hinge device of the tenth invention is an articulated hinge device of one of the first to the ninth inventions, wherein the articulated hinge device is configured to ensure that a back side cover portion covering a frame portion is provided on a back side of the frame portion, wherein the back side cover portion has a plurality of longitudinal cover plates formed in the shape of longitudinal strip, aligned along the width direction and rotatably coupled to each other around a longitudinal axis, wherein the longitudinal cover plate at one end in the width direction among the plurality of longitudinal cover plates is engaged with the first base plate to be movable in the width direction relative to the first base plate, while the cover plate at the other end of the width direction is engaged with the second base frame to be movable in the width direction relative to the second base frame.

An electronic device of the eleventh invention comprises a first casing, a second casing, and a flexible display sheet mounted over the inner surfaces of both the first and the second casings, a flexible display sheet and an articulated hinge device of any of the first to tenth inventions coupling the first and second casings in a foldable manner by a relative folding motion between the open and closed positions and arranged on the back side of the flexible display sheet.

According to the first invention, when the first casing and the second casing are opened and closed relative to each other, the surface of the frame portion describes parabola to turn from a flat to a semicircular arc-shaped surface, and the folded part of the flexible display sheet is held in place following the surface of the frame portion10. Therefore, the folded part of the flexible display sheet, which is folded in a semicircular arc shape, can be stably held in the closed position without swaying. In addition, no sag or wrinkling occurs when the product is used in an opened state.

According to the second invention, the sliding engagement of arc-shaped arms with guide hole portions can ensure that adjacent frames alter the gap between them by changing the direction and angle of their rotation relative to each other along a predetermined trajectory, wherein the length in the width direction of the frame portion corresponding to the string length is short, and the length in the width direction of the frame portion corresponding to the arc length is long in the closed position. Therefore, no sag nor other problems occur at the folded part of the flexible display sheet.

According to the third invention, articulation joints are arranged with a good balance in the longitudinal and width directions of a frame row to allow smooth rotation movement of each frame making up the frame row due to opening and closing operation.

According to the fourth invention, the curved surface which the opening and closing operation describes on the surface of the frame portion can be a symmetrical parabola centered on the first vertical frame, and there is no partial stress concentration in the bent part of the flexible display sheet, which can prevent damage to the flexible display sheet.

According to the fifth invention, if a plurality of synchronous gear trains are distributedly arranged in a frame row, an entire synchronous driving portion can be more compact and an articulated hinge device itself can be thinner.

According to the sixth invention, it is possible to realize the rotation movement of adjacent frames relative to each other in a simple structure.

According to the seventh invention, even longer arc-shaped arms can avoid an interference of their tips with other vertical frames, etc. and assure the opening and closing operation.

According to the eighth invention, a stress applied to arc-shaped arms and guide hole portions is dispersed to realize a smooth opening and closing operation by avoiding an interference between adjacent articulation joints and by distributedly arranging the joint contacts in a vertical direction.

According to the ninth invention, a first friction click stop mechanism and a second friction click stop mechanism can be housed along the vertical direction in the first base frame and the second base frame, respectively, so that an articulated hinge device can be made more compact, that components making up the first and second friction click stop mechanisms can be also arranged vertically, and that the first friction click stop mechanism and the second friction click stop mechanism can be made more compact.

According to the tenth invention, the back side of the frame section can be covered following an opening and closing movement.

According to the eleventh invention, an articulated hinge device can protect the folded part of a flexible display sheet and provide a foldable electronic device with reduced occurrence of failure of the flexible display sheet.

EMBODIMENT

In the following, reference is made to an articulated hinge device according to the invention and an electronic device using the articulated hinge device, based on embodiments shown in the drawings.

FIGS.1and2show a perspective view of appearance of an electronic device using an articulated hinge device according to the invention. A flexible display sheet4made e.g. of organic EL is attached to an electronic device1, wherein organic light emitting diodes (OLEDs) are used as light emitting diodes of a bendable display member over respective surfaces of a first casing2and a second casing3. The first casing2and the second casing3are coupled to each other via an articulated hinge device5; these casings are coupled to each other to have a flexible display sheet4bendable inward between a closed state in which one contact another facing each other with display surfaces, and an opened state in which both are opened 180 degrees relative to each other. The following description is made based on a notebook PC as an example of the electronic device1, but further examples include various electronic devices such as mobile phone, electronic notebook, PDA, netbook.

In an opened state in which a first casing2and a second casing3are opened 180 degrees relative to each other, and where X-, Y- and Z-axes are three axes perpendicular to each other, a direction in which the first casing2and the second casing3are aligned in X-axis direction is referred to as a width direction (also referred to as a right and left direction), while a hinge axis direction perpendicular to the width direction in Y-axis direction as a vertical direction and a Z-axis direction as a front and rear surface direction. In the vertical direction, a side close to the user is referred to as a front side, while a side opposite to the user as a rear side, in the state in which the first casing2and the second casing3are opened in the right and left direction, as shown inFIG.2. Still further, in the front and rear surface direction, a front surface side is also referred to as an inner surface side, while a rear surface side as a back surface side.

An articulated hinge device5is bent in U-shape as seen from the front side in a closed state shown inFIG.3, and unfolded to be flat in the right and left direction in an opened state shown inFIG.4. A support sheet6having flexibility on its surface and a rectangular flat plate shape is attached to the articulated hinge device5.

Next, reference is made to components of an articulated hinge device5, based on exploded perspective views shown inFIG.5AtoFIG.5D.

FIG.5Ashows an overall structure of an articulated hinge device5, whileFIG.5B—front side parts of a frame portion10of the articulated hinge device5, as well as an articulated portion50, a synchronous driving portion70on a front side and an intermediate portion of a first and a second base frames30A,30B.FIG.5Cshows rear side parts of a frame portion10of the articulated hinge device5, the first and the second base frames30A,30B, as well as an articulated portion50on a rear side, and a first and a second friction click stop portions90A,90B being stop holding portions.FIG.5Dshows a back side cover portion110.

An articulated hinge device5comprises a frame portion10configured to ensure that five elongated vertical frames11to15extending in a vertical direction are aligned, a first base frame30A fixed by screws (not shown) to the first casing2and a second base frame30B fixed by screws (not shown) to the second casing3. Still further, the articulated hinge device5comprises articulated portions50, a synchronous driving portion70as well as a first and a second friction click stop portions90A,90B.

<Schematic Structure of Frame Portion10>

Five elongated vertical frames11to15of a frame portion10are all formed substantially in the shape of rectangular parallelepiped, with shorter sides in a width direction and longer sides in a vertical direction, wherein each single frame is made up with a plurality of frame bodies fixed in series along the vertical direction. A vertical frame arranged in the center in the width direction is referred to as a first vertical frame11, while those on the left side in the width direction from the first vertical frame11are referred to as a left second vertical frame12and a left third vertical frame13sequentially toward a first base frame30A. Still further, vertical frames on the right side in the width direction from the first vertical frame11are referred to as a right second vertical frame14and a right third vertical frame15sequentially toward a second base frame30B. The left second vertical frame12and the left third vertical frame13are referred to as one group, a left frame group10A, while the right second vertical frame14and the right third vertical frame15—as a right frame group10B. In this embodiment the left frame group10A and the right frame group10B are arranged on the right and left of the first vertical frame11.

<Schematic Structure of First Base Frame30A and Second Base Frame30B>

A first base frame30A is made up with a front first base frame body31A and a rear first base frame32A coupled to each other in series along a vertical direction, wherein their coupling parts are fixed to each other by screws201,202, as shown inFIG.7. A second base frame30B is made up with a front second base frame body31B and a rear second base frame32B coupled to each other in series along a vertical direction, wherein their coupling parts are fixed to each other by screws203,204. Stepped portions33respectively with a lower inner side and a higher outer side as seen in a right and left direction are formed on front surface sides of a first base frame30A and a second base frame30B. A stepped portion33has a height equal to a thickness of a support sheet6, and the support sheet6is arranged in the inner side of the stepped portion33.

A first friction click stop portion90A is provided on a rear first base frame32A, and a second friction click stop portion90B on a rear second base frame32B.

An articulated portion50comprises a left first articulation joint51A provided between a first vertical frame11and a left second vertical frame12, a left second articulation joint52A provided between the left second vertical frame12and a left third vertical frame13, and a left third articulation joint53A provided between the left third vertical frame13and a first base frame30A. Furthermore, it comprises a right first articulation joint51B provided between a first vertical frame11and a right second vertical frame14, a right second articulation joint52B provided between the right second vertical frame14and a right third vertical frame15, and a right third articulation joint53B provided between the right third vertical frame15and a second base frame30B. The left first articulation joint51A to the left third articulation joint53A and the right first articulation joint51B to the right third articulation joint53B make up a set.

A left first articulation joint51A and a left third articulation joint53A on one hand, and a right first articulation joint51B and a right third articulation joint53B are all provided at the same position in a vertical direction, while a left second articulation joint52A and a right second articulation joint52B are provided rearward from the left first articulation joint51A. Articulated portions50realize a movement for realizing variations of gap between frames, i.e. each vertical frame11to15of a frame portion10, a first base frame30A and a second base frame30B, with changing a direction and an angle of their rotation (this movement is hereinafter referred to as articulated hinge movement).

In this embodiment, three articulated portions50in total are provided on both end portions in the vertical direction and at an intermediate position to realize a smooth articulated hinge movement. The one on a front side in the vertical direction is referred to as a first row articulated portion50A, while the one at an intermediate position as a second row articulated portion50B and the one on a rear side in the vertical direction as a third row articulated portion50C.

Articulated portions50provide a displacement trajectory for assuring by the articulated hinge movement a continuous shift from a bent state in the U-shape to a flat state, in a front view of a frame portion10along the front and rear direction, by a relative opening and closing of a first casing2and a second casing3between a closed state at a position where the first casing2contact the second casing3facing each other with display surfaces (at a minus angle beyond 0 degree) and an opened state in which both are opened 180 relative to each other.

In this embodiment, a left first to a left third articulation joints51A to53A of a first row articulated portion50A provided on the left side of a first vertical frame11realize variations between frames i.e. the first vertical frame11, respective left vertical frames12,13of a left first frame group10A and a first base frame30A, while altering their rotation directions and angle relative to each other between an opening and closing angle of 0 degree and that of substantially 90 degrees (slightly greater than 90 degrees). Similarly, a first to a right third articulation joints51B to53B provided on the right side of a first vertical frame11realize variations between frames, the first vertical frame11, respective left vertical frames14,15of a right first frame group10B and a second base frame30B, while altering their rotation directions and angle of relative to each other between an opening and closing angle of 0 degree and that of substantially 90 degrees.

A left trajectory where the left first frame group10A and the first base frame30A are bent with realizing variations between frames while altering their rotation directions and angle and a right trajectory where the right first frame group10B and the second base frame30B are bent with realizing variations between frames while altering their rotation directions and angle are symmetrical on the right and left about the first vertical frame11.

As shown inFIG.5A,FIG.5B,FIG.9andFIG.10, a first, a second and a left third articulation joints51A,52A and53A making up a first row articulated portion50A comprise respectively a left first to a left third arc-shaped arms61ato61c, and a left first to a left third guide hole portions62ato62crespectively provided on a first vertical frame11, a left second vertical frame12and a left third vertical frame13, wherein the left first to the left third guide hole portions extend toward the left, are formed in the shape identical to the left first to the left third arc-shaped arms, and the left first to the left third arc-shaped arms61ato61care slidably engaged with the left first to the left third guide hole portions. A left first guide hole portion62ais formed on the left second vertical frame12, while a left second guide hole portion62bon the left third vertical frame13and the left third guide hole portion62con right side surface of the first base frame30A.

The left first to the left third arc-shaped arms61ato61cform curved surfaces63(seeFIG.9andFIG.10) for providing an arc-shaped displacement trajectory extending toward a front surface in a front and a rear direction on their front and a rear surfaces. On a left first to a left third guide hole portions62ato62c, an inner circumferential surface64(seeFIG.9andFIG.10) is formed, wherein the curved surface63on a front and a rear surfaces of the left first to the left third arc-shaped arms61ato61cabut against the inner circumferential surface. The left guide hole portions62ato62care guided by the curved surface63between a base side and a tip portion of the left first to the left third arc-shaped arms61ato61cto be slidably engaged with the left first to the left third arc-shaped arms.

Still further, a first to a right third articulation joints51B to53B arranged on the right side of a first vertical frame11are arranged in a horizontal symmetry with a left first to a left third articulation joints51A to53A centered on the first vertical frame11. A first to a right third arc-shaped arms65ato65cand a first to a right third guide hole portions66ato66care respectively formed in a horizontal symmetry with a left first to a left third arc-shaped arms61ato61cand a left first to a left third guide hole portions62ato62c. The right first to the right third arc-shaped arms65ato65cform a curved surface67(seeFIG.9andFIG.10) for assuring an arc-shaped displacement trajectory on their front and rear surfaces, and extend toward the right side. The right first to the right third guide hole portions66ato66ccomprising an inner circumferential surface68(seeFIG.9andFIG.10), wherein the curved surface67on the front and the rear surfaces abut against the right first to the right third guide hole portions, are formed on a right second vertical frame14, a right third vertical frame15and a second base frame30B. The right guide hole portions66ato66care guided by the curved surface67between a base side and a tip portion of the right first to the right third arc-shaped arms65ato65cto be slidably engaged with the right first to the right third arc-shaped arms.

It is noted that, inFIG.5AandFIG.5B, as per components of a second row articulated portion50B, a left first to a left third arc-shaped arms are denoted with reference numerals261ato261c, while a right first to a right third guide hole portions with262ato262c, a right first to a right third arc-shaped arms with265ato265cand a right first to a right third guide hole portions with266ato266c. Equally, inFIG.5AandFIG.5C, as per components of a third row articulated portion50C, a left first to a left third arc-shaped arms are denoted with reference numerals361ato361c, while a right first to a right third guide hole portions with362ato362c, a first to a right third arc-shaped arms with365ato365cand a right first to a right third guide hole portions with366ato366c.

Reference is made to the articulated hinge movement, in reference to an example of the first row articulated portion50A. In this embodiment, three articulation joints, the left first articulation joint51A, the left second articulation joints52A and the left third articulation joints53A provided on the left side of the first vertical frame11realize variations between adjacent frames, i.e. the first vertical frame11and the left second vertical frame12, the left second vertical frame12and the left third vertical frame13, and the left third vertical frame13and the first base frame30A, while altering directions and angle of their rotation relative to each other at an angle between of 0 degree to 30 degrees, to assure rotation. When the left first to the left third articulation joints51A to53A are rotated between 0 degree and 30 degrees by this articulated hinge movement, a trajectory described by each frame of the first vertical frame11to the first base frame30A has a bent arc shape having an opening and closing angle of 90 degrees from a horizontal state (quarter arc shape). Equally three articulation joints, a right first to a right third articulation joints51B to53B provided on a right side of a first vertical frame11are also respectively rotated between 0 degree and 30 degrees.

On the other hand, a flexible display sheet4has a freely deformable portion4aof constant length in a right and left direction over a first casing2and a second casing3. Based on examples of chord length and arc length in an arc, a chord length is longer than an arc length. If a length from the first base frame30A through the frame portion10to the second base frame30B in an opened state is a chord length, the chord length must be longer than a length from the first base frame30A through the frame portion10to the second base frame30B in the width direction, to deform the freely deformable portion4ainto a deformed shape in a closed state. To this end, the left first to the left third articulation joints51A to53A and the right first to the right third articulation joints51B to53B realize variations in gaps between respective frames relative to each other, to expand and contract the distance between the adjacent frames on the right and left (in the width direction).

It is noted that if the rotation angle is slightly greater than 30 degrees, the opposed surfaces of the flexible display sheet4can be inclined surfaces and the outer ends in the right and left direction of the first casing2and the second casing3can abut against each other in the closed state, as shown inFIG.31.

In the opened state shown inFIG.9andFIG.10,FIG.9shows a left first articulation joint51A, a right first articulation joint51B, a left third articulation joint53A and a right third articulation joint53B; andFIG.10shows the left second articulation joints52A and the right second articulation joint52B. In all articulation joints51A to53A;51B to53B, the left first to the left third guide hole portions62ato62care engaged with the left first to the left third arc-shaped arms61ato61cat the base portion of the latter, and the right first to the right third guide hole portions66ato66cwith the right first to the right third arc-shaped arms65ato65c. In this engaged state, the first base frame30A, respective vertical frames11to15of the frame portion10and the second base frame30B are aligned with no gap between them in the right and left direction to be flat.

The left first to the left third arc-shaped arms61ato61cand the right first to the right third arc-shaped arms65ato65care engaged with the left first to the left third guide hole portions62ato62cand the right first to the right third guide hole portions66ato66cin a range from a base portion (at a rotation angle of 0 degree) to a rotation angle slightly greater than 30 degrees. The left first to the left third arc-shaped arms61ato61cand the right first to the right third arc-shaped arms65ato65chave a length (arc length) longer than the width of vertical frames on which the left first to the left third guide hole portions62ato62cand the right first to the right third guide hole portions66ato66care provided. To this end, the insertion holes69a,69b(seeFIG.10) being relief holes are formed on the first base frame30A and the second base frame30B, wherein the tip portions of the left second arc-shaped arm61band the right second arc-shaped arm65bare inserted into these holes, and the insertion holes69c,69d(seeFIG.9) are formed on the left and right left third vertical frame13,15, wherein the tip portions of the left first arc-shaped arm61aand the right second arc-shaped arm65aare inserted into these holes, once these tip portions have passed through the left first guide hole portion62aand the right first guide hole portions66a. The inner circumferential surfaces of the insertion holes69a,69bare formed in a shape which forces the tip portions of the left second arc-shaped arm61band the right second arc-shaped arm65bto be slidably engaged with no backlash. Equally, the inner circumferential surfaces of the insertion holes69c,69dare formed in a shape which forces the tip portions of the left first arc-shaped arm61aand the right second arc-shaped arm65ato be slidably engaged with no backlash.

Reference is briefly made to a structure of a frame portion10, as well as to an attaching part of an arc-shaped arm and guide hole portion in each vertical frame.

A first vertical frame11of a frame portion10is made up by coupling seven frame bodies, a first to a seventh frame bodies21A to21G in series in a vertical direction, while a left second vertical frame12is made up by coupling five frame bodies, an eighth to a twelfth frame bodies22A to22E in series in a vertical direction. Still further, a left third vertical frame13is made up of a thirteenth to an eighteenth frame bodies23A to23F, while a right second vertical frame14of a nineteenth to a twenty-third frame bodies24A to24E and a right third vertical frame15of a twenty-fourth to a twenty-ninth frame bodies25A to25F. A fifth frame body21E, an eleventh frame body22D, a seventeenth frame body23E, a twenty-second frame body24D and a twenty-eighth frame body25E are length-adjusting frame bodies for adjusting a vertical length of the entire frame portion10to a vertical length of a first casing2and a second casing3. Frame bodies respectively making up each vertical frame11to15are coupled by screws (not shown) screwed from a front surface to a rear surface side.

A left first arc-shaped arm61aand a right second arc-shaped arm65aare formed integrally with a first frame body21A for a first row articulated portion50A of the first vertical frame11, and a left first arc-shaped arm261aand a right first arc-shaped arm265awith a fourth frame body21D for a second row articulated portion50B. A left first arc-shaped arm361aand a right first arc-shaped arm365aare formed integrally with a seventh frame body21G for a third row articulated portion50C.

A left first guide hole portion62ais formed on an eighth frame body22A for a first row articulated portion50A of a left second vertical frame12. The left first guide hole portion62ais formed by fixing by screws (not shown) a left guide block662bto a left guide hole main body portion662aformed on an eighth frame body22A. A left second arc-shaped arm61bis formed integrally on an eighth frame body22A. A left second arc-shaped arm261bis formed integrally on a ninth frame body22B for a second row articulated portion50B. A left first guide hole portion62ais made up of a left guide block662bon a tenth frame body22C for a second row articulated portion50B. A left second arc-shaped arm361bis formed integrally on a twelfth frame body22E for a third row articulated portion50C, and a left first guide hole portion362ais made up of the left guide block662b.

A left third arc-shaped arm61cis formed integrally on a thirteenth frame body23A for a first row articulated portion50A of a third vertical frame13, and an insertion hole69cformed on the third vertical frame. A left second guide hole portion62bis formed integrally on a fourteenth frame body23B for a first row articulated portion50A. A left guide block662bis formed integrally on a rear end portion of a fifteenth frame bodies23C for a second row articulated portion50B, and a left guide hole main body portion662aformed integrally on a front end portion of a sixteenth frame bodies3D for the second row articulated portion50B. Then, a left second guide hole portion62bis formed by coupling the fifteenth frame body23C to the sixteenth frame body23D. An insertion hole69c, into which a tip of the left first arc-shaped arm61ais inserted, is formed on the sixteenth frame bodies23D. A left first guide hole portion362ais made up of a left guide block662b, and a left third arc-shaped arm361cformed integrally on an eighteenth frame body23F for a third row articulated portion50C. Still further, an insertion hole69fis formed on the eighteenth frame body23F, wherein a tip portion of the left first arc-shaped arm361ais inserted into the insertion hole.

A right first guide hole portion66ais made up of a right guide block666bon a nineteenth frame body24A for a first row articulated portion50A of a right second vertical frame14. A right second arc-shaped arm65bis formed integrally on a twentieth frame body24B for a first row articulated portion50A. A right second arc-shaped arm265bis formed integrally on a twenty first frame body24C for a second row articulated portion50B, and a right first guide hole portion266ais made up of a right guide block666b. A right second arc-shaped arm365bis formed integrally with a twenty third frame body24E for a third row articulated portion50C, and a right first guide hole portion366ais made up of the right guide block666b.

A right third arc-shaped arm65cis formed integrally on a twenty fourth frame body25A for a first row articulated portion50A of a right third vertical frame15, and a right second guide hole portion66bis made up of the right guide block666b. The right guide block666bis formed integrally on a rear end portion of a twenty fifth frame body25B for a second row articulated portion50B, a left guide hole main body portion662aformed integrally on a front end portion of a twenty sixth frame body25C, and a right second guide hole portion66bis formed by coupling the twenty fifth frame body25B to the twenty sixth frame body25C. A right third arc-shaped arm65cis formed integrally on a twenty seventh frame body25D for a second row articulated portion50B. A right second guide hole portion366bis made up of the right guide block666bon a twenty ninth frame body25F for a third row articulated portion50C, a right third arc-shaped arm365cis formed integrally and an insertion hole69i(seeFIG.18), into which a right first arc-shaped arm365ais inserted, is formed as well.

On the other hand, a right third guide hole portion366cwith which a right third arc-shaped arm365cis engaged is made up of a right guide block666bon a rear second base frame body32B of a second base frame30B, and an insertion hole (not shown), into which a tip portion of a right second arc-shaped arm365bis inserted, is formed as well.

A right third guide hole portion266cwith which a right third arc-shaped arm265cof a second row articulated portion50B is slidably engaged is made up of the right guide block666bon a front second base frame body31B. Moreover, an insertion hole (not shown), into which a tip portion of a right second arc-shaped arm265bof the second row articulated portion50B is inserted is formed on the front second base frame body31B. Still further, a right third guide hole portion66cwith which a right third arc-shaped arm65cis slidably engaged is made up of a left guide block666bon the front second base frame body31B.

On the other hand, an insertion hole69gis formed on a front first base frame body31A of the first base frame30A, wherein a left second arc-shaped arm261bof a second row articulated portion50B is inserted into the insertion hole, and a left third guide hole portion262cis made up of the left guide block662b, wherein a left third arc-shaped arm261cof a second row articulated portion50B is slidably engaged with the left third guide hole portion. Still further, an insertion hole69his formed on the rear first base frame body32A, wherein a tip portion of a left second arc-shaped arm361bof a third row articulated portion50C is inserted into the insertion hole, and a left third guide hole portion362cis formed, wherein a left third arc-shaped arm361cis slidably engaged with the left guide hole portion.

A first base frame30A and a left third vertical frame13changes directions and angle of rotation within a predetermined rotation angle range between 0 degree and a maximum rotation angle slightly greater than 30 degrees, by a slide engagement of a left third arc-shaped arm (61c,261c,361c) and a left third guide hole portion (62c,262c,362c), to expand and contract the gap between a first base frame30A and the left third vertical frame13. A left third vertical frame13and a left second vertical frame12change directions and angle of rotation within the above-mentioned rotation angle range relative to each other by a slide engagement of a left second arc-shaped arm (61b,2610,361h) and a left third guide hole portion (62b,262b,362b), and the left second vertical frame12and the first vertical frame11do so by that of a left second arc-shaped arm (61b,261b,361b) and a left third guide hole portion (62a,262a,362a), to expand and contract the gap between adjacent frames. Further frames such as a right second vertical frame14and a right third vertical frame15on the right side of the first vertical frame11and a second base frame30B also change directions and angle of rotation within the above-mentioned rotation angle range relative to each other, to make the gap between adjacent frames expandable and contractable.

Articulated portions50change directions and angle of rotation of adjacent frames relative to each other along a predetermined trajectory by a slide engagement of arc-shaped arms and guide hole portions, and make the gap between adjacent frames expandable and contractable; they assure a synchronous driving motion for a synchronous driving portion70, and a stop motion for stopping a shift movement at any position and for holding a gap at a stop position by a first friction click stop portion90A and a second friction click stop portion90B. The synchronous driving portion70is made up by coupling a plurality of gears along a width direction from a first base frame30A through a frame portion10to a second base frame30B. When a first base frame30A and a second base frame30B are subjected to an opening and closing movement relative to each other by an opening and closing movement of a first casing2and a second casing3relative to each other, coupling gears on both ends (a front first coupling gear92A, a rear first coupling gear93A, a front second coupling gear92B and a rear second coupling gear93B fixed to a left third vertical frame13and a right third vertical frame15), which are respectively coupled to a first friction click stop portion90A and a second friction click stop portion90B respectively provided on the first base frame30A and the second base frame30B, shift to synchronously drive respective gears between them. Next, when a rotation of the coupling gears on both ends stops, the one of the gears between them does so as well, and the respective frames to which the respective gears are attached stop to be held at that position. Furthermore, the coupling gears on both ends are braked by friction force, to apply a resistive force to the opening and closing movement of the first casing2and the second casing3. This resistive force enables the first casing2and the second casing3to be held by the resistive force at that position in an opening and closing state, even if the first casing2and the second casing3are stopped in the middle of the opening and closing movement of the first casing2and the second casing3.

<Structure of Synchronous Driving Portion70>

InFIG.5B, synchronous driving portion70is made up of four synchronous gears of identical structure, i.e. a left first synchronous gear train71A, a left second synchronous gear train72A, a right first synchronous gear train71A and a right second synchronous gear train72A. The left first synchronous gear train71A and the left second synchronous gear train72A comprise respectively a left first synchronous gear portion80A and a left second synchronous gear portion80B, while the right first synchronous gear train71B and the right second synchronous gear train72B comprise respectively a right first synchronous gear portion80C and a right second synchronous gear portion80D. Each of the left first synchronous gear portion80A, the left second synchronous gear portion80B, the right first synchronous gear portion80C and the right second synchronous gear portion80D is unitized of a left synchronous gear81and a right synchronous gear82being aligned in a right and left direction along a width direction.

A left first synchronous gear train71A is arranged between a first vertical frame11and a left third vertical frame13adjacent to a left second vertical frame12on the right and the left in a width direction, centered on a left first synchronous gear portion80A. A left first synchronous gear portion80A is arranged on a coupling portion of a ninth frame body22B and a tenth frame body22C, both making up the left second vertical frame12. Bearing holes (not shown) for a front shaft portion81aof a left synchronous gear81and a front shaft portion82aof a right synchronous gear82aligned on the right and left along the width direction are formed on a rear end portion of the ninth frame body22B. Bearing holes81c,82cfor a rear shaft portion81bof the left synchronous gear81and a rear shaft portion82bof the right synchronous gear82are formed on a front end portion of the tenth frame body22C. The ninth frame body22B and the tenth frame body22C are fixed to each other by screws (not shown) screwed along the right and left direction to make up a synchronous gear unit for rotatably holding the left synchronous gear81and the right synchronous gear82meshed with each other.

A first arc-shaped gear83is meshed with a left synchronous gear81, while a second arc-shaped gear84with a right synchronous gear82. The first arc-shaped gear83and the second arc-shaped gear84have symmetrical shapes on the right and left, and as shown inFIG.11andFIG.12, a gear portion86is formed on an outer circumferential surface of an arc-shaped gear body85bent into a convex shape toward a rear surface side. The first arc-shaped gear83and the second arc-shaped gear84are arranged to be spaced apart from front to rear in a vertical direction. A screw insertion hole87is provided on a left end portion of the first arc-shaped gear83, and the gear portion86extends toward the right. A screw insertion hole88is provided on a left end portion of the second arc-shaped gear84, and the gear portion86extends toward the left.

On a left first synchronous gear train71A, a first arc-shaped gear83is fixed by a screw87a(seeFIG.7) to a sixteenth frame body23D making up a left third vertical frame13, and a second arc-shaped gear84is fixed by a screw88a(seeFIG.7) to a third frame body21C making up a first vertical frame11.

When the first arc-shaped gear83is rotated clockwise integrally with the left third vertical frame13, a left synchronous gear81is rotated counterclockwise, as is the case with a driving operation of rack gear and pinion gear. Here, a rotation angle of the left third vertical frame13increases along a predetermined trajectory by a slidable engagement of a left second arc-shaped arm61b(261b,361b) and a left second guide hole portion62b(262b,362b), the left third vertical frame13gradually stands up from a horizontal direction and shifts to expand the gap with a left second vertical frame12. On the other hand, when a left synchronous gear81is rotated counterclockwise, a right synchronous gear82is rotated clockwise and a second arc-shaped gear84counterclockwise. Therefore, a first vertical frame11is rotated counterclockwise relative to the left second vertical frame12along a predetermined trajectory by a slidable engagement of left first arc-shaped arms61a(261a,361a) and left first guide hole portions62a(262a,362a), its rotation angle gradually increases, the first vertical frame11stands up from the horizontal direction and shifts to expand the gap with the left second vertical frame12. Here, if the first vertical frame11taken as reference point, the left second vertical frame12is rotated clockwise relative to the first vertical frame11, and the left third vertical frame13clockwise relative to the left second vertical frame12.

On a left second first synchronous gear train72A, a left second synchronous gear portion80B is provided as a synchronous gear unit between a thirteenth frame body23A and a fourteenth frame body23B, both making up the left third vertical frame13. A first arc-shaped gear83is fixed by a screw87b(seeFIG.7) to a front first base frame body31A of a first base frame30A, and a second arc-shaped gear84is fixed by a screw88b(seeFIG.7) to an eighth frame body22A making up a left second vertical frame12.

On a left second first synchronous gear train72A, when a first casing2is rotated in a closing direction, a first base frame30A is rotated clockwise, a first arc-shaped gear83clockwise and a left synchronous gear81counterclockwise. Here, a rotation angle of the first base frame30A increases along a predetermined trajectory by a slidable engagement of a left third arc-shaped arm61c(261c,361c) and a left third guide hole portion62c(262c,362c), the first base frame30A gradually stands up from a horizontal direction and shifts to expand the gap with a left third vertical frame13. On the other hand, when a left synchronous gear81is rotated counterclockwise, a right synchronous gear82is rotated clockwise and a second arc-shaped gear84counterclockwise. Therefore, the left second vertical frame12is rotated counterclockwise relative to the left third vertical frame13along a predetermined trajectory by a slidable engagement of left second arc-shaped arms61b(261b,361b) and left second guide hole portions62b(262b,362b), its rotation angle gradually increases, the left third vertical frame13stands up from the horizontal direction and shifts to expand the gap with the left, third vertical frame13. Here, if the left second vertical frame12taken as reference point, the left third vertical frame13is rotated clockwise relative to the left second vertical frame12. A clockwise turning force of the left first synchronous gear train71A relative to the left second vertical frame12is transferred via the left second synchronous gear portion80B of the left second first synchronous gear train72A.

Next, reference is made to a right first synchronous gear train71B and a right second synchronous gear train72B. The right first synchronous gear train71B and the right second synchronous gear train72B have a structure substantially identical to a left first synchronous gear train71A and a left second first synchronous gear train72A as described above, except the former are arranged at a position point-symmetric to the latter, if a center of a front half part of a first vertical frame11in a vertical direction taken as reference point.

A right first synchronous gear train71B arranges a right first synchronous gear portion80C on a coupling portion of a nineteenth frame body24A and a twentieth frame body24B of a right second vertical frame14, and fixes a first arc-shaped gear83is by a screw87c(seeFIG.7) to a second frame body21B of a first vertical frame11. A second arc-shaped gear84is fixed by a screw88c(seeFIG.7) to a twenty fourth frame body25A of a right third vertical frame15.

When a right third vertical frame15is rotated counterclockwise, a second arc-shaped gear84is rotated counterclockwise, a right synchronous gear82clockwise and a left synchronous gear81counterclockwise. Then, a first arc-shaped gear83fixed to a first vertical frame11meshed with the left synchronous gear81is rotated clockwise. Therefore, a right second vertical frame14is rotated clockwise relative to the right third vertical frame15along a predetermined trajectory by a slidable engagement of a right second arc-shaped arm65b(265b,365b) and a right first guide hole portion66b(266b,366b). As the first arc-shaped gear83is rotated clockwise, the first vertical frame11is rotated clockwise relative to the right second vertical frame14.

On the contrary, as seen from a first vertical frame11, a right second vertical frame14is rotated counterclockwise along a predetermined trajectory by a slidable engagement of a right first arc-shaped arm65a(265a,365a) and a right first guide hole portion66a(266a,366a). Here, a rotation angle of the right second vertical frame14increases, the right second vertical frame14gradually stands up from a horizontal direction and shifts to expand the gap with the first vertical frame11. A right third vertical frame15is rotated counterclockwise relative to the right second vertical frame14along a predetermined trajectory by a slidable engagement of a right second arc-shaped arm65h(265b,365b) and a right first guide hole portion66h(266h,366b). Here, a rotation angle of the right third vertical frame15increases, the right third vertical frame15gradually stands up from a horizontal direction and shifts to expand the gap with the right second vertical frame14.

A right second synchronous gear train72B arranges a right second synchronous gear portion80D on a coupling portion of a twenty-sixth frame body25C and a twenty-seventh frame body25D of a right third vertical frame15, and fixes a first arc-shaped gear83by a screw87d(seeFIG.7) to a second frame body24C of a right second vertical frame14. A second arc-shaped gear84is fixed by a screw88d(seeFIG.7) to a front base frame body31B of a second base frame30.

On the other hand, when a second base frame30B is rotated counterclockwise, a second arc-shaped gear84is rotated counterclockwise, a right synchronous gear82clockwise and a left synchronous gear81counterclockwise. Then, a first arc-shaped gear83fixed to a right second vertical frame14meshed with a left synchronous gear81is rotated clockwise. Therefore, a right third vertical frame15is rotated counterclockwise relative to the second base frame30B along a predetermined trajectory by a slidable engagement of a right third arc-shaped arm65c(265c,365c) and a right third guide hole portion66c(266c,366c). As the first arc-shaped gear83is rotated clockwise, the right second vertical frame14is rotated clockwise relative to the right third vertical frame15.

On the contrary, as seen from the right second vertical frame14, the right third vertical frame15is rotated counterclockwise along a predetermined trajectory by a slidable engagement of a right second arc-shaped arm65b(265b,365b) and a right second guide hole portion66b(266b,366b). Here, a rotation angle of the right third vertical frame15increases, the right third vertical frame15gradually stands up from a horizontal direction and shifts to expand the gap with the right second vertical frame14. Therefore, the left second vertical frame12is rotated counterclockwise relative to the right third vertical frame15along a predetermined trajectory by a slidable engagement of a right third arc-shaped arm65c(265c,365c) and a right third guide hole portion66c(266c,366c). Here, a turning angle of the second base frame30B increases, the second base frame30B gradually stands up from a horizontal direction and shifts to expand the gap with the right third vertical frame15. A clockwise turning force of the right first synchronous gear train71B relative to the right third vertical frame15is transferred via the right second synchronous gear portion80D of the right first synchronous gear train71B.

In a description of left and right, first and second synchronous gear trains71A,71B,72A,72B, reference is also made to application of a turning force to first and second base frames30A,30B to show that these are rotated relative to each other; this applies for example to the case that a second casing3is in a resting state, while a first casing2is opened and closed. When an opening and closing force is applied to both the first casing2and the second casing3, a turning force as accompanied with an opening and closing motion of the first base frame30A and the second base frames30B is applied from left and right third vertical frames13,15to left and right second vertical frames12,14respectively.

A synchronous gear train73having the same structure as first synchronous gear train71A is provided on rear end portions in a vertical direction respectively of a first vertical frame11and left and right second vertical frames12,14. The synchronous gear train73is arranged on a coupling portion to a sixth frame body21F and a seventh frame body21G of the first vertical frame11to fix a first arc-shaped gear83by a screw87e(seeFIG.7) to a twelfth frame body22E making up a left second vertical frame12, as well as a second arc-shaped gear84by a screw88e(seeFIG.7) to a twenty third frame body24E making up a right second vertical frame14. The synchronous gear train73functions as a frame holding portion for holding the first vertical frame11, and the left and right second vertical frames12,14following shift trajectories of a left first articulation joint51A and a right first articulation joint51B along their respective predetermined shift trajectories, with no rattling.

Left and a right, first and second synchronous gear portions80A to80D of a synchronous driving portion70are subjected to gear-coupling to each other in series by a first arc-shaped gear83and a second arc-shaped gear84, and each of the gears is fixed to each frame of frame rows (which means a first base frame30A, respective vertical frames11to15of a frame portion10and a second base frame30B which are all arranged in parallel to each other). This prevents each frame of the frame rows from individually shifting other than gear drive of the synchronous driving portion70.

<Structure of Friction Click Stop Portion (Stop Holding Portion)>

InFIG.5CandFIG.6, a first friction click stop portion90A and a second friction click stop portion90B are provided symmetrically on the right and left on a rear end portion in a vertical direction, centered on a central shaft line L along the vertical direction of a first vertical frame11. The first friction click stop portion90A comprises a first friction click stop mechanism91A provided on a rear first base frame32A of a first base frame30A, a front first coupling gear92A and a rear first coupling gear93A fixed respectively to the front and the rear of an eighteenth frame body23F making up a left third vertical frame13. The second friction click stop portion90B comprises a second friction click stop mechanism91B provided on a rear second base frame32B of a second base frame30B, a front second coupling gear92B and a rear second coupling gear93B fixed respectively to the front and the rear of a twenty ninth frame body25F making up a right second vertical frame15. The front first coupling gear92A and the rear first coupling gear93A are formed in an arc shape similar to a second arc-shaped gear84, while the front second coupling gear92B and the rear second coupling gear93B in an arc shape similar to a first arc-shaped gear83.

In this embodiment, a first friction click stop mechanism91A is composed of two units, i.e. a front first unit94A and a rear first unit95A, while a second friction click stop mechanism91B of two units, i.e. a front second unit94B and a rear second unit95B; both are structured in an identical structure, symmetrical on the right and the left. Furthermore, a front first coupling gear92A and the rear first coupling gear93A are provided in correspondence with the two units, i.e. the front first unit94A and the rear first unit95A, while a front second coupling gear92B and a rear second coupling gear93B in correspondence with the two units, i.e. the front second unit94B and the rear second unit95B.

A first friction click stop mechanism91A pivotally supports a first driving shaft100A and a second driving shaft100B between a front end bearing portion100C and a rear end bearing portion100D, as well as on an intermediate area by a front intermediate bearing portion100E and a rear intermediate bearing portion100F. The front end bearing portion100C, the rear end bearing portion100D, the front intermediate bearing portion100E and the rear intermediate bearing portion100F are fixed on a rear surface side (an inner surface side) of a rear first base frame32A by screws (not shown).

A first driving shaft100A and a second driving shaft100B have an identical structure, in that they are formed in so-called two surface width shape, having two opposed surfaces of columnar shaft portions (which have maximum outer diameters) as parallel surfaces, wherein a flange portion100G is formed on a central area in an axial direction. A front first unit94A is provided on a front side, and a rear first unit95A on a rear side, symmetrically in a front and rear direction across a boundary of the flange portion100G. Small diameter shaft portions100H,100I pivotally supported by the front intermediate bearing portion100E and the rear intermediate bearing portion100F are formed on the first driving shaft100A and the second driving shaft100B. The small diameter shaft portions100H,100I have smaller diameters than the maximum outer diameters of the first driving shaft100A and the second driving shaft100B.

A left synchronous gear101A and a right synchronous gear101B meshed with each other, as is the case with a left first synchronous gear portion80A are non-rotatably mounted on both end portions of small diameter shaft portions100H,100I. Shaft holes of the left synchronous gear101A and the right synchronous gear101B are formed to conform to two surface widths of the first driving shaft100A and the second driving shaft100B.

A front first unit94A is configured to ensure that in a first driving shaft100A and a second driving shaft100B, a first common friction plate102A, a left and a right first friction plates103A,103A, a common click plate104, a left and a right click bodies105,105, a left and a right compression springs106,106, a left and a right second friction plates103B,103B and a second common friction plate102B are arranged in order from a front side between a front intermediate bearing portion100E and a flange portion100G. Shaft holes of the first and the second common friction plates102A,102B and the common click plate104are formed in the circular shape having the maximum outer diameter, while shaft holes of the left and the right first friction plates103A,103A, the left and the right click bodies105,105, in the shape conforming to two surface widths of the first driving shaft100A and the second driving shaft100B. The left and the right click bodies105,105have adequately larger diameters than the maximum outer diameters of the first driving shaft100A and the second driving shaft100B.

Top surfaces102a,104ein a front surface and a rear surface direction of the first and the second common friction plates102A,102B and the common click plate104are formed on a flat surface to abut against a ceiling surface on a rear surface side of a rear first base frame body32A. Therefore, even if a rotation force of the first driving shaft100A and the second driving shaft100B about an axis is applied to the first and the second common friction plates102A,102B and the common click plate104, rotations of the first and the second common friction plates102A,102B and the common click plate104are stopped.

A rear first unit95A is configured to ensure that in a first driving shaft100A and a second driving shaft100B, a second common friction plate102B, a left and a right second friction plates103B,103B, a common click plate104, a left and a right click bodies105,105, a left and a right compression springs106,106, a left and a right first friction plates103A,103A and a first common friction plate102B, are arranged in order from a rear side toward a front side between a rear intermediate bearing portion100F and a flange portion100G, as shown inFIG.6.

A first common friction plate102A and a left and a right first friction plates103A,103A, and a common click plate104and a left and a right click bodies105,105and of a left and a right second friction plates103B,103B and a second common friction plate102B are under a pressurized contact by spring forces of a left and the right compression springs106,106. The left and the right first friction plates103A,103A as well as the left and the right second friction plates103B,103B are under a friction contact with the first common friction plate102A and the second common friction plate102B to apply a friction force as the left and the right first friction plates103A,103A are rotated by a rotation of a first driving shaft100A and a second driving shaft100B.

Cam portions104A,104A are formed on a common click plate104extending toward a left and a right click bodies105,105, wherein convex portions104band concave portions104care alternately formed respectively at an angular interval of 90 degrees about axes of shaft holes104a,104ainto which a first driving shaft100A and a second driving shaft100B are inserted. Tip portions104dof the convex portions104bare formed into flat surfaces.

Click projection portions105band concave portions105care alternately formed respectively at an angular interval of 90 degrees about axes of shaft holes105aon a left and a right click bodies105,105extending toward convex portions104bof cam portions104A. Tip portions105dof the click projection portions105bare formed into flat surfaces. On the left and a right click bodies105,105, a click projection portion105brotatably shifts between a convex portion104band a concave portion104cof a cam portion104A at a closed position and an opened position. A first driving shaft100A and a second driving shaft100B are rotated 90 degrees between an opened position and a closed position. For example, as shown inFIG.6, the click projection portion105bshifts from the closed position where it is interstitially inserted into the concave portion104cof the cam portion104A to the opened position where it abuts against a tip portion104dof a convex portion104b.

A first input gear107A and a second input gear107B formed in a shaft shape and meshed with each other are aligned in a right and left direction between a front end bearing portion100C and a front intermediate bearing portion100E, while a third input gear107C and a fourth input gear107D formed in a shaft shape are aligned along a right and left direction between a rear end bearing portion100D and a rear intermediate bearing portion100F. The first input gear107A is meshed with a right synchronous gear101B of a front first unit94A, while the second input gear107B with a front first coupling gear92A. The third input gear107C is meshed with a right synchronous gear101B of a rear first unit95A, while the fourth input gear107D is meshed with a rear first coupling gear93A. As a rotation is transferred to the second input gear107B and the fourth input gear107D by the front first coupling gear92A and the rear first coupling gear93A, respective right synchronous gears101B of the front first unit94A and the rear first unit95A are rotated via the first input gear107A and the third input gear107C to assure a synchronous rotation of respective left synchronous gears101A. As the left and the right synchronous gears101A,101B are rotated, the first driving shaft100A and the second driving shaft100B are rotated. Four respective first and second friction plates103A,103B are under a friction contact with first and second common friction plates102A,102B to apply a friction braking force to a rotation force on the first driving shaft100A and the second driving shaft100B. Still further, when tip portions105dof the click projection portions105bof a left and a right click bodies105,105ride on respective tip portions104dof respective convex portions104bof a common click plate104, a click feeling is obtained.

A second friction click stop portion90B has a structure identical to a first friction click stop portion90A, both being symmetrically structured about a first vertical frame11and having the same effect, so that the same elements have the same reference numerals and no explanation is made to the former. A first input gear107A, a second input gear107B, a left and a right synchronous gears101A,101B make up an input gear, and similarly a third input gear107C, a fourth input gear107D, a left and a right synchronous gears101A,101B make up an input gear.

<Structure of Back Side Cover Portion110>

An articulated hinge device5is configured to ensure that a back side cover portion110is provided on a back side of a frame portion10that covers the frame portion10being an outer surface side of a notebook PC1. The back side cover portion110is configured to ensure that an outer vertical cover plate112A and an inner vertical cover plate112B are alternately aligned in a symmetry on the right and left centered on a central vertical cover plate111in the center in a width direction, while a left end vertical cover plate113A is added at the left end in the width direction and a right end vertical cover plate113B at the right end in the width direction. These vertical cover plates (111,112A,112B,113A,113B) are formed in the shape of strips short in the width direction and elongated along a vertical direction, wherein short piece portions114respectively project perpendicular from both ends of the vertical direction toward a front surface. The inner vertical cover plate112B and the left and the right vertical cover plates113A,113B have an equal length in a vertical direction such that they sink in slightly inwardly in the vertical direction from the short piece portions114on both ends of the outer vertical cover plate112A. Moreover, where the vertical cover plates (111,112A,112B,113A,113B) are arranged in parallel in the width direction, each short piece portion114of the outer vertical cover plate112A is located further outward from each short piece portion114of adjacent cover plates, i.e. inner vertical cover plates112B on both sides, the left end vertical cover plate113A and the right end vertical cover plate113B. Therefore, when a frame portion10changes its form into a bent state and a flat state between a closed state shown inFIG.3and an opened state shown inFIG.4, adjacent short piece portions114do not interfere with each other, but do shield the inside of an articulated hinge device5from the outside to prevent dust from entering.

As shown inFIG.5DandFIG.9, a central vertical cover plate111, an outer vertical cover plate112A and an inner vertical cover plate112B are configured to ensure that respectively first engagement groove115are formed along a vertical direction on a left lateral edge in a width direction to have an opening toward a rear surface side, while second engagement groove116formed along a vertical direction on a right lateral edge in a width direction to have an opening toward a front surface side. A left end vertical cover plate113A is configured to ensure that a first engagement groove115is formed on a right lateral edge, and a right end vertical cover plate113B is configured to ensure that a first engagement groove115is formed on a left lateral edge. These vertical cover plates (111,112A,112B,113A,113B) are configured to ensure that the first engagement groove115and the second engagement groove116are engaged with each other, and that the vertical cover plates (111,112A,112B,113A,113B) adjacent about the axial line in a vertical direction are freely rotatable.

As shown inFIG.5D, a screw hole117is formed on a fitting convex portion118on front surfaces of both end portions in a vertical direction of a central vertical cover plate111, and the central vertical cover plate111is fixed on a first vertical frame11by screwing a screw212(seeFIG.7) into the screw hole117, as the screw is inserted into a front end portion of the first vertical frame11of a frame portion10. Respective fitting convex portions118are formed on front surfaces of both end portions in a vertical direction of an outer vertical cover plate112A and an inner vertical cover plate112B, wherein the fitting convex portions project from the front surfaces toward inner surfaces. Fitting concave portions119are formed on rear surfaces of both end portions in the vertical direction of the first vertical frame11, left and right second vertical frames12,14and left and right third vertical frames13,15of the frame portion10. The fitting convex portions118are fitted to be non-displaceable in the vertical direction relative to fitting concave portions119, and freely slidable along a right and left direction. Therefore, a vertical shift of the central vertical cover plate111, the outer vertical cover plate112A and the inner vertical cover plate112B is restricted. It is noted that since the central vertical cover plate111is fixed by the screw12to the first vertical frame11, the first vertical frame11does not shift relative to the central vertical cover plate111.

A left slide engagement piece120and a right slide engagement piece121are respectively formed from tips of short piece portions114provided on both end portions in a vertical direction of a left end vertical cover plate113A and a right end vertical cover plate113B toward an inner side in a vertical direction. As shown inFIG.5B, the left slide engagement piece120is slidably engaged with left groove122of small width respectively formed on both end surfaces in the vertical direction of a first base frame30A to extend in a width direction. Furthermore, the right slide engagement piece121is slidably engaged with right groove123of small width respectively formed on both end surfaces in the vertical direction of a second base frame30B to extend in a width direction.

In a closed state shown inFIG.3, a left and a right slide engagement pieces120,121are engaged with left groove122and right groove123at their inner end portions, and in an opened state shown inFIG.4, a left and a right slide engagement pieces120,121are engaged with left groove122and right groove123at their outer end portions. While a total length (length in a width direction) of a frame portion10varies by effects of articulated portions50in accordance with an opening and closing operation of a first casing2and a second casing3, a length in a width direction of a back side cover portion110remains constant. In order to absorb the variations in total length of the frame portion10, the back side cover portion110slides the left and the right slide engagement pieces120,121relative to the left groove122and the right groove123.

Next, reference is made to the opening and closing operation of the articulated hinge device5structured as mentioned above, based onFIG.7toFIG.31.

FIG.7shows a top view of the articulated hinge device5in the opened state, the support sheet6being removed. As shown inFIG.8, the articulated hinge device5is configured to be less thick in the opened state.

Where the first vertical frame11is arranged at the center in the width direction inFIG.7, the first vertical frame11, the left second vertical frame12, the left third vertical frame14and the first base frame30A are held in a state, wherein their lateral surfaces are in contact with no gap in the width direction. Similarly, the first vertical frame11, the right second vertical frame14, the right third vertical frame15and the second base frame30B are held in a state, wherein their lateral surfaces are in contact with no gap in the width direction. In the opened state, the surface levels of these adjacent frames have no difference and no irregularities.

InFIG.7, the cross section taken in arrows J11-J11shows the left and the right first articulation joints51A,51B and the third articulation joints53A,53B of the first row articulated portion50A in the opened state, as shown inFIG.9. The cross section taken in arrows J12-J12shows the left and the right second articulation joints52A,52B, as shown inFIG.10. The cross section taken in arrows G11-G11shows the meshing position of the second arc-shaped gear84, and the right synchronous gear82in the left second synchronous gear train72A, as well as the meshing position of the second arc-shaped gear84and the right synchronous gear82in the right first synchronous gear train71B, as shown inFIG.11. The cross section taken in arrows G12-G12shows the meshing position of the first arc-shaped gear83and the left synchronous gear81in the left second synchronous gear train72A, as well as the meshing position of the first arc-shaped gear83in and the left synchronous gear81in the right first synchronous gear train71B, as shown inFIG.12. The cross section taken in arrows G13-G13shows the meshing position of the fourth input gear107D and the rear first coupling gear93A of the rear first unit95A in the first friction click stop portion90A, as well as the meshing position of the fourth input gear107D and the rear second coupling gear93B of the rear second unit95B in the second friction click stop portion90B, as shown inFIG.13. It is noted that the cross sections shown inFIG.9toFIG.13facilitate an understanding of structure by displaying the length in thickness direction of the articulated hinge device5twice as long as the length magnified at the same magnification level as remaining elements. The cross sections shown inFIG.16toFIG.21,FIG.24toFIG.29have the same magnification level.

As shown inFIG.9, respective pairs of the first vertical frame11and the left second vertical frame12, of the left second vertical frame12and the left third vertical frame13, and of the left third vertical frame13and the first base frame30A are aligned with no gap horizontally in the width direction, on the left side in the width direction based on the first vertical frame11. Respective pairs of the first vertical frame11and the right second vertical frame14, of the right second vertical frame14and the right third vertical frame15, and of the right third vertical frame15and the right base frame30B are aligned with no gap horizontally in the width direction, on the right side in the width direction based on the first vertical frame11.

The left first guide hole portion62aprovided on the left second vertical frame12is engaged with an area toward the base portion of the left first arc-shaped arm61aextending from the first vertical frame11toward the left. In this state, the turning angle of the left second vertical frame12is 0 degree. The tip portion of the left first arc-shaped arm61ais inserted into the insertion hole69cprovided on the left third vertical frame13to avoid the interference with the left third vertical frame13. The right first guide hole portion66aprovided on the right second vertical frame14is engaged with an area toward the base portion of the right first arc-shaped arm65aextending from the first vertical frame11toward the right. In this state, the turning angle of the right second vertical frame14is 0 degree. The tip portion of the right first arc-shaped arms65ais inserted into the insertion hole69dprovided on the right third vertical frame15to avoid the interference with the right third vertical frame15.

The left third guide hole portion62cprovided on the first base frame30A is engaged with an area toward the base portion of the left third arc-shaped arm61cextending from the left third vertical frame13toward the left. In this state, the turning angle of the first base frame30A is 0 degree. The right third guide hole portion66cprovided on the second base frame30B is engaged with an area toward the base portion of the right third arc-shaped arm65cextending from the right third vertical frame15toward the right. In this state, the turning angle of the second base frame30B is 0 degree. In other words, no turning force in a closing direction is applied to the first base frame30A and the second base frame30B.

Furthermore, as shown inFIG.10, the left second guide hole portion62bprovided on the left third vertical frame13is engaged with an area toward the base portion of the left second arc-shaped arm61bextending from the left second vertical frame12toward the left. In this state, the turning angle of the left third vertical frame13relative to the left second vertical frame12is 0 degree. The tip portion of the left second arc-shaped arm61bis inserted into the insertion hole69aprovided on the first base frame30A to avoid the interference with the first base frame30A. Similarly, the right second guide hole portion66bprovided on the right third vertical frame15is engaged with an area toward the base portion of the right second arc-shaped arm65bextending from the right second vertical frame14toward the right. In this state, the turning angle of the right third vertical frame15relative to the right second vertical frame14is 0 degree. The tip portion of the right second arc-shaped arm65bis inserted into the insertion hole69bprovided on the second base frame30B to avoid the interference with the second base frame30B.

The tip portions of the left and the right arc-shaped arms61a,65aare formed into flat surfaces, and the flat tip portions of the left and the right arc-shaped arms61a,65aabut against the opening edges of the insertion holes69ato69dto have a function of preliminary stopper and to maintain the horizontal state.

As shown inFIG.11, the left second synchronous gear train72A is configured to ensure that the second arc-shaped gear84provided on the left second vertical frame12is meshed with the right synchronous gear82of the left second synchronous gear portion80B provided on the left third vertical frame13in the opened state. The right first synchronous gear train71B is configured to ensure that the second arc-shaped gear84provided on the right third vertical frame15is meshed with the right synchronous gear82of the right first synchronous gear portion80C provided on the right second vertical frame14. The second arc-shaped gear84is meshed at its base portion with the right synchronous gear82.

The left synchronous gear81of the left second synchronous gear train72A and the respective left synchronous gears81of the right first synchronous gear train71B shown inFIG.11are meshed with the first arc-shaped gear83fixed to the first base frame30A and the first arc-shaped gear83fixed to the first vertical frame11, as shown inFIG.12. The base portion of the first arc-shaped gear83is meshed with the left synchronous gear81.

Furthermore, in the opened state, the rear first coupling gear93A is meshed at its base portion with the fourth input gear107D of the rear first unit95A in the first friction click stop portion90A, as shown inFIG.13. Similarly, the rear second coupling gear93B is meshed at its base portion with the fourth input gear107D of the rear second unit95B in the second friction click stop portion90B. In this opened state, the cam portions104A of the common click plate104and the left and the right click bodies105assure the state in which the click projection portions105bare fitted into the concave portions104cof the cam portions104A.

FIG.30shows a cross section of the electronic device1in the opened state shown inFIG.2, along its folding direction, further corresponding to a cross section of the articulated hinge device5as shown inFIG.9. The back side cover portion110is held to be flat, and the left end vertical cover plate113A and the right end vertical cover plate113B reach the ends in the right and left direction of the first base frame30A and the second base frame30B.

FIG.14shows a top view of the articulated hinge device5, andFIG.15is an elevation view ofFIG.14, showing the intermediate opened and closed state lying between the opened state and the closed state. The articulated hinge device5shifts from the flat state to the bent state in the intermediate opened and closed state.

InFIG.14, the first vertical frame11, the left second vertical frame12, the left third vertical frame13and the first base frame30A are aligned in the width direction, wherein their lateral surfaces respectively have small gaps. Similarly, the first vertical frame11, the right second vertical frame14, the right third vertical frame15and the second base frame30B are aligned in the width direction, wherein their lateral surfaces respectively have small gaps.

InFIG.14, the cross section taken in arrows J21-J21(which is the same cross section area as the cross section taken in arrows J11-J11inFIG.9), which shows the articulated portions50is shown inFIG.16, and the cross section taken in arrows J22-J22(which is the same cross section area as the cross section taken in arrows J12-J12) inFIG.17. The cross section taken in arrows J23-J23, which shows the third row articulated portion50C is shown inFIG.18. The one in G21-G21cross section area (which is the same cross section area as the cross section taken in arrows G11-G11inFIG.11) is shown inFIG.19, while the one in G22-G22cross section area (which is the same cross section area as the cross section taken in arrows G12-G12inFIG.12) is shown inFIG.20and the one in G23-G23cross section area (which is the same cross section area as the cross section taken in arrows G13-G13inFIG.13) is shown inFIG.21.

Though the left first synchronous gear train71A and the right second synchronous gear train72B are not shown inFIG.11andFIG.12(FIG.20,FIG.21,FIG.27andFIG.28), reference is now made toFIG.16toFIG.21, while the meshed state of the left first synchronous gear train71A and the right second synchronous gear train72B is additionally described in reference toFIG.5B.

As shown inFIG.16,FIG.17andFIG.18, when the first base frame30A and the second base frame30B are turned from the opened state in the closing direction, in the first base frame30A, the left third guide hole portion62c(362c) provided on the first base frame30A is turned, while it shifts toward the left in the drawings along the trajectory described by the curved surface63of the left third arc-shaped arms61c(361c) and changes its orientation upward. Furthermore, the right third guide hole portion66c(366c) provided on the second base frame30B is turned, while it shifts toward the right in the drawings along the trajectory described by the curved surface67of the right third arc-shaped arms65c(365c) and changes its orientation upward. Therefore, the gap between the first base frame30A and the left third vertical frame13are wider, and the gap between the right third vertical frame15and the second base frame30B are wider. InFIG.18the third row articulated portion50C has a structure identical to the first row articulated portion50A, and behaves in the same manner as the latter.

InFIG.17, the left second articulation joints52A is configured to ensure that the left second guide hole portion62bprovided on the left third vertical frame13is engaged with an area almost in the middle of the left second arc-shaped arm61bprovided on the left second vertical frame12. Furthermore, the right second articulation joint52B is configured to ensure that the right second guide hole portion66bprovided on the right third vertical frame15is engaged with an area almost in the middle of the right second arc-shaped arm65bprovided on the right second vertical frame14.

As the positions of the respective frames (11to15,30A and30B) inFIG.16are compared to those inFIG.9, the frames (12to15,30A and30B) arranged on the right and left in the width direction, centering around the first vertical frame11turns the same angle and open the gaps to the same stroke. Therefore, based on the first vertical frame11, the turning angle of the first base frame30A is the sum of the turning angle of the left second vertical frame12, the turning angle of the left third vertical frame13and the turning angle of the first base frame30A. This also applies to the second base frame30B. Moreover, as the shift trajectories by the slide engagements of the respective arc-shaped arms and the respective guide hole portions form a single parabola, the front surfaces of the respective vertical frames11to15of the frame portion10and of the first and the second base frames30A,30B assure the arc shape of small curvature at the intermediate opening and closing position.

Therefore, the freely deformable portion4aof the flexible display sheet4is held following the curved surface formed by the respective frames11to15of the frame portion10and by the first and the second base frames30A,30B. Moreover, in the back side cover portion110, the engagement position of the left end vertical cover plate113A and the right end vertical cover plate113B relative to the first base frame30A and the second base frame30B shift toward the inner side along the width direction.

Reference is made to the operation of the synchronous driving portion70, based onFIG.19andFIG.20, wherein the respective vertical frames11to15of the frame portion10, as well as the first base frame30A and the second base frame30B are all driven in a synchronous manner, the curved surface formed by the front surfaces of the respective vertical frames11to15, as well as of the first base frame30A and of the second base frame30B is a parabola.

As shown inFIG.20, the left second synchronous gear train72A is configured to ensure that the turning motion of the first arc-shaped gear83fixed to the first base frame30A turning clockwise enables left synchronous gear81of the left second synchronous gear portion80B to be rotated counterclockwise, and the right synchronous gear82to be rotated clockwise. InFIG.19, during a clockwise rotation of the right synchronous gear82of the left second synchronous gear portion80B, the right synchronous gear82turns around on its own axis and shifts its meshing position with the second arc-shaped gear84toward the tip portion. Therefore, the left second vertical frame13turns clockwise and shifts to open the gap with the left second vertical frame12, as shown inFIG.16.

The left first synchronous gear train71A is configured to ensure that the base portion of the first arc-shaped gear83fixed to the left third vertical frame13is meshed with the left synchronous gear81of the left first synchronous gear portion80A provided on the left second vertical frame12. The second arc-shaped gear84fixed to the first vertical frame11is meshed at its base portion with the right synchronous gear82of the left first synchronous gear portion80A. Therefore, when the left third vertical frame13turns clockwise by the operation from the opened state to the closed state, the meshed position of the first arc-shaped gear83with the left synchronous gear81shifts from the base portion to the tip portion to force the left synchronous gear81to be rotated counterclockwise. Then, the right synchronous gear82meshed with the left synchronous gear81is rotated clockwise. Here, the right synchronous gear82turns around clockwise on its own axis and shifts its meshing position with the second arc-shaped gear84from the base portion to the tip portion. Therefore, the left second vertical frame12turns clockwise and shifts relative to the first vertical frame11.

In other words, when the first base frame30A turns clockwise in the closing direction, with the first vertical frame11as a reference point, the left first synchronous gear train71A forces the left and the right synchronous gears81,82of the left first synchronous gear portion80A to turn around on its own axis and to turn clockwise and shift. Therefore, the left second vertical frame12having the first synchronous gear portion80A opens the gap with the first vertical frame11, while it shifts along the predetermined trajectory.

In this manner, the left first synchronous gear train71A has an effect of forcing the left second vertical frame12having the left first synchronous gear portion80A to shift relative to the first vertical frame11in the direction for opening the gap and of forcing the left third vertical frame13to shift relative to the left second vertical frame12in the direction for opening the gap.

Moreover, inFIG.19andFIG.20, the left second synchronous gear train72A forces the left and the right synchronous gears81,82of the left second synchronous gear portion80B to turn around on its own axis and to turn clockwise and shift, the left third vertical frame13having the left second synchronous gear portion80B opens the gap with the second vertical frame12, while it shifts along the predetermined trajectory.

On the other hand, in reference toFIG.5B, the right second synchronous gear train72B is configured to ensure that the base portion of the first arc-shaped gear83fixed to the right second vertical frame14is meshed with the left synchronous gear81of the right second synchronous gear portion80D provided on the right third vertical frame15. The second arc-shaped gear84fixed to the second base frame30B is meshed at its base portion with the right synchronous gear82of the right second synchronous gear portion80D. Therefore, when the second base frame30B turns counterclockwise to realize a shift from the opened state to the closing operation, the second arc-shaped gear84turning counterclockwise displaces its meshed position with the right synchronous gear82to force the right synchronous gear82to be rotated clockwise. Then, the left synchronous gear81meshed with the right synchronous gear82is rotated counterclockwise. The right second synchronous gear portion80D is configured to ensure that the left synchronous gear81turning counterclockwise is meshed with the first arc-shaped gear83fixed on the right second vertical frame14and turns around on its own axis to turn counterclockwise and shift. Therefore, the right third vertical frame15opens the gap with the right second vertical frame14shifts by turning counterclockwise.

As shown inFIG.19andFIG.20, when the right third vertical frame15turns counterclockwise, the right synchronous gear82of the right first synchronous gear80C is rotated clockwise and the left synchronous gear81rotates counterclockwise. As shown inFIG.20, when the left synchronous gear81of the right first synchronous gear portion80C is rotated counterclockwise, the left synchronous gear81turns on its own axis to displace its meshed position with the first arc-shaped gear83and turns counterclockwise and shifts. Therefore, the right second vertical frame14expands the gap with the first vertical frame11to turn counterclockwise and shift.

In other words, when the right second synchronous gear train72B realizes the shift of second base frame30B from the opened state to the closed state, it expands the gap between the right third vertical frame15and the second base frame30B and forces the right third vertical frame15to turn and shift in the direction for expanding the gap with the right second vertical frame14.

On the other hand, when the second base frame30B turns counterclockwise and shifts, the second arc-shaped gear84of the right first synchronous gear train71B rotates the right synchronous gear82of the right first synchronous gear portion80C clockwise via the right second synchronous gear train72B, as shown inFIG.19. Then, as shown inFIG.20, the left synchronous gear81turns around on its own axis and is meshed with the first arc-shaped gear83to turn counterclockwise and shift, so that the right second vertical frame14expands its gap with the first vertical frame11.

FIG.19andFIG.20show the right first synchronous gear train71B and the left second synchronous gear train72A in their intermediate opened and closed state. As the right first synchronous gear train71B and the left second synchronous gear train72A in their opened state inFIG.11is compared toFIG.19, the meshed position of the second arc-shaped gear84with the right synchronous gear82is at its base portion inFIG.11, while it shifts from its base portion toward its tip portion inFIG.19. Similarly, asFIG.20is compared toFIG.12, the meshed position of the first arc-shaped gear83with the left synchronous gear81shifts from its base portion inFIG.12toward its tip portion inFIG.20.

In the intermediate opened and closed state, the first friction click stop portion90A and the second friction click stop portion90B are meshed with the fourth input gear107D in the state, where the rear first coupling gear93A and the rear second coupling gear93B have shifted from the base side to the middle position toward the tip portion. The first friction click stop portion90A and the second friction click stop portion90B rotates the first driving shaft100A and the second driving shaft100B while the right synchronous gears101B are rotated by the synchronous rotation of the third input gear107C, and the left synchronous gears101A meshed with the right synchronous gears101B are rotated. The rotating friction plates, i.e. first friction plates103A and the second friction plates103B are in friction contact with the non-rotatable friction plates, i.e. first common friction plate102A and the second common friction plate102B. Therefore, when the first casing2and the second casing3turn in the closing direction from the opened state to the intermediate opened and closed state, they are under resistive force by friction. Then, the first casing2and the second casing3stop to close at the intermediate opened and closed state, the shift motion of the synchronous driving portion70is locked by friction resistance, and the respective vertical frames11to15, the first base frame30A and the second base frame30B are held at the intermediate opened and closed state.

FIG.22shows a top view of the articulated hinge device5in the closed state, andFIG.23—an elevation view ofFIG.22. InFIG.22, the cross sections showing the articulated portions50taken in arrows J31-J31, J32-J32, J33-J33, G31-G31, G32-G32, G33-G33show the same cross section areas as the cross section taken in arrows J21-J21, J22-J22, J23-J23, G21-G21, G22-G22, G23-G23inFIG.14.

The cross sections taken in arrows in J31-J31is shown inFIG.24, while the one in J32-J32inFIG.25and the one in J33-J33inFIG.26. In the state where the first base frame30A and the second base frame30B are parallel to each other, or in the closed state where the both are closed slightly inward from the parallel state, the left first guide hole portion62ais engaged with the left first arc-shaped arm61aat the tip portion of the latter. Similarly, the other guide hole portions62b,62c,66a,66b,66care engaged with the tip portion of the arc-shaped arms61b,61c,65a,65b,65c. As compared toFIGS.16to17showing the intermediate opened and closed state, the guide hole portions engaged with the intermediate portions of the arc-shaped arms further displace their engaging positions toward the tip portion sides, so that the respective vertical frames11to15, the first base frame30A and the second base frame30B increase their turning angle to the adjacent frames, expand the gap and shift.

If the first vertical frame11is taken as reference point, the sum of the turning angles of the first vertical frame11, the first base frame30A, the respective vertical frames12,13between them respectively relative to their adjacent frames is substantially 90 degrees. Furthermore, the sum of the turning angles of the first vertical frame11, the second base frame30B, the respective vertical frames14,15between them respectively relative to their adjacent frame is substantially 90 degrees.

The cross section taken in arrows G31-G31is shown inFIG.27, while the one in G32-G32inFIG.28. A comparison to the intermediate opened and closed state shown inFIGS.20and21relates to the meshed position with the left second synchronous gear portion80B, the first arc-shaped gear83and the second arc-shaped gear84of the left second synchronous gear train72A, as well as to the meshed position of the right first synchronous gear portion80C, the first arc-shaped gear83and the second arc-shaped gear84of the right first synchronous gear train71B.

In the closed state, the tip portion of the second arc-shaped gear84on the left side in the width direction as seen from the first vertical frame11is meshed with the right synchronous gear82of the left second synchronous gear portion80B, while the tip portion of the second arc-shaped gear84on the right side in the width direction as seen from the first vertical frame11is meshed with the right synchronous gear81of the right first synchronous gear portion80C, as shown inFIG.27. Moreover, the tip portion of the first arc-shaped gear83on the left side in the width direction as seen from the first vertical frame11is meshed with the left synchronous gear81of the second synchronous gear portion80B, while the tip portion of the first arc-shaped gear83on the right side in the width direction as seen from the first vertical frame11with the left synchronous gear81of the right first synchronous gear portion80C, as shown inFIG.28.

The synchronous driving portion70has an effect to displace the meshed position of the first arc-shaped gear83with the left synchronous gear81from the base portion of the first arc-shaped gear83to the tip portion during the shift from the opened state to the closed state, and to displace the meshed position of the second arc-shaped gear84with the right synchronous gear82from the base portion of the second arc-shaped gear84to the tip portion. Moreover, on the contrary, it displaces the meshed position of the first arc-shaped gear83with the left synchronous gear81from the tip portion of the first arc-shaped gear83to the base portion during the shift from the closed state to the opened state, and displaces the meshed position of the second arc-shaped gear84with the right synchronous gear82from the tip portion of the second arc-shaped gear84to the base portion.

The respective vertical frames11to15, the first base frame30A and the second base frame30B, as these frames are guided by the articulation joints (51A to53A,51B to53B) of the articulated portions50, are synchronously driven by the respective synchronous gears (71A,72A,71B,72B) in the direction in which the adjacent frames approach and in the direction in which they come away from each other. Here, the respective frames change the orientation and angle of their rotation relative to each other to change the gap between the frames.

As shown inFIG.29, in the first friction click stop portion90A and the second friction click stop portion90B, the tip portions of the rear first coupling gear93A and the rear second coupling gear93B are meshed with the fourth input gear107D as compared toFIG.21. Therefore, when the first casing2and the second casing3turn between the opened state and the closed state, they are under resistive force by friction. Furthermore, in the opened state, a click feeling is obtained by forcing the click projection portions105bof the click bodies105to abut against the tip portions104dof the left and the right cam portions104A of the common click plate104against the spring force of the compression springs106. In the closed state, a click feeling is obtained by forcing the click projection portions105bto be fitted into the concave portions104cof the cam portions104A by the spring force of the compression springs106.

FIG.31shows the closed state of the electronic device1, wherein the first casing2and the second casing3are folded to face each other, and in the articulated hinge device5, the front surface of the frame portion10composed of the five vertical frames is curved in semi-circular shape. Therefore, the freely deformable portion4aof the flexible display sheet4is held on the front surface of the frame portion10in semi-circular shape.

In the embodiment as described above, though reference has been made to the case that the first casing2and the second casing3are opened and closed at the same time, the articulated hinge device5also behaves similarly in case that the first casing2only is opened and closed relative to the second casing3placed on the desk.

Furthermore, though the frame portion10in the embodiment as described above is described based on the example of the single left first frame group10A and the single right first frame group10B, a plurality of first frame groups10A and a plurality of right first frame groups10B can be provided.

The number of vertical frames of the frame portion10is an odd number of five or more, and one or more left first frame group(s)10A and right first frame group(s)10B can be respectively provided on the right and left along the width direction of the first vertical frame11. Therefore, for the number N of vertical frames in the frame portion10, N can be expressed as N=1+2n, where n is an integer greater than or equal to 2. Articulated portions50may be provided at both ends of the vertical direction.

The articulated hinge device can hold the bent part of the flexible display sheet following the frame portion which forms an arc-shaped trajectory when the first casing and second casing are opened and closed. Therefore, the bent part of the flexible display sheet folded in a semicircular arc shape, can be stably held in the closed position without swaying. In addition, no sag or wrinkling occurs when the product is used in an opened state.

The invention is a hinge device suitably used in a folding electronic device, such as smartphone, electronic notebook, PDA, netbook, a video display device, portable game machine and notebook PC, which is built by attaching a flexible display sheet across respective surfaces of a first and a second casings; it can further be suitably used as an electronic device using such a hinge device.