Hinge apparatus for electronic device

A hinge apparatus for an electronic device includes a cam unit and a gear unit provided at a connecting position of an upper plate and a lower plate. The cam unit includes a first cam mechanism for causing a first cam shaft connected to an upper plate to generate a torque and a second cam mechanism for causing a second cam shaft connected to a lower plate to generate a torque. Further, the gear unit includes a first gear shaft connected to the upper plate and a second gear shaft connected to the lower plate, a first gear provided in the first gear shaft, a first gear provided in the second gear shaft, and a gear mechanism that synchronizes and rotates the first gear shaft and the second gear shaft.

TECHNICAL FIELD

The present invention relates to a hinge apparatus for an electronic device such as a portable terminal that oscillates a lid body part relative to a main body part.

BACKGROUND ART

A collapsible electronic device such as a portable telephone or a laptop computer includes, for example, a main body part including ten-keys or the like and a lid body part including a liquid crystal display or the like. Further, a hinge apparatus is provided at a connecting area between the main body part and the lid body part for rotating (oscillating) the lid body part relative to the main body part.

A hinge apparatus used for the above-described type of electronic device is disclosed in Patent Document 1. The hinge device for the electronic device disclosed in Patent Document 1 is a so-called double shaft type hinge apparatus. With the double shaft type hinge apparatus, the lid body part can be rotated 180 degrees about a first rotation shaft relative to the main body part. In addition, the main body part can be rotated 180 degrees about a second rotation shaft relative to the lid body part. Therefore, as a whole, the lid body part can be rotated 360 degrees relative to the main body part.

Further, the hinge apparatus disclosed in Patent Document 1 has a cam mechanism and a gear mechanism integrally provided therein. By providing the cam mechanism, a toggle is generated when the lid body part is positioned having a predetermined rotation angle relative to the main body part, to thereby retain the lid body part. Accordingly, visibility of the liquid crystal display or the like can be improved.

RELATED ART REFERENCE

Patent Document

DISCLOSURE OF THE INVENTION

Problem to be Solved by Invention

Because the conventional hinge apparatus for an electronic device has the cam mechanism and the gear mechanism integrally provided inside the hinge apparatus, it is inevitable for the size to become large. Therefore, as illustrated in Patent Document 1, the conventional hinge apparatus for an electronic device is arranged at a center area of the electronic device.

However, the center area of the electronic device is where main electronic circuits and electronic components of the electronic device (hereinafter referred to as “main components and the like”) are arranged. Thus, conventionally, due to the hinge apparatus occupying a large area of the center area of the electronic device, there are problems such as lack of degree of freedom for arranging the main components and size increase of the electronic device.

Means for Solving Problem

It is a general object of the present invention to provide an improved useful hinge apparatus for an electronic device that solves the above-described problems of the related art.

It is a specific object of the present invention to provide a hinge apparatus for an electronic device that improves the efficiency of using space of the electronic device.

In order to achieve such object, the present invention provides a hinge apparatus for an electronic device including a cam unit; and a gear unit; wherein the cam unit includes a cam cover, a first cam shaft that is rotatably arranged in the cam cover and connected to a first cam bracket fixed to a first plate, a first cam mechanism that causes the first cam shaft to generate a torque, a second cam shaft configured to independently rotate relative to the first cam shaft and connected to a second cam bracket fixed to a second plate, and a second cam mechanism that causes the second cam shaft to generate a torque, wherein the gear unit includes a gear cover, a first gear shaft that is rotatably arranged in the gear cover and connected to a first cam bracket fixed to the first plate, a first gear part arranged in the first gear shaft, a second gear shaft that is rotatably arranged in the gear cover and connected to a second cam bracket fixed to the second plate, a second gear part arranged in the second gear shaft, and a gear mechanism including the first gear part and the second gear part, and configured to synchronize and rotate the first gear shaft and the second gear shaft, wherein the cam unit and the gear unit are positioned away from and faced against the first and second plates that are rotatable relative to each other.

Further, in the present invention, the first gear shaft and the second gear shaft may be configured to rotate in different directions relative to each other.

Further, in the present invention, the first and second cam mechanisms may be configured to generate the torque one time when the second plate is rotate 360 degrees relative to the first plate.

Effect of the Invention

With the present invention, by arranging a cam unit (which generates a torque at a predetermined rotation position) and a gear unit (which performs synchronization when first and second plates are rotated) separate from each other, components and the like can be arranged between the cam unit and the gear unit. Thereby, the efficiency of using the space of an electronic device having a hinge apparatus mounted thereon can be improved.

EXPLANATION OF REFERENCE NUMERALS

EMBODIMENTS OF THE INVENTION

As illustrated inFIG. 1, a hinge apparatus D1for an electronic device according to an embodiment of the present invention includes a cam unit5and a gear unit6. The cam unit5and the gear unit6have a function of opening/closing an upper plate relative to a lower plate9.

The cam unit5, which is positioned on the left side inFIG. 1, includes an upper cam bracket1and a lower cam bracket2. Further, the gear unit6, which is positioned on the right side inFIG. 1, includes an upper gear bracket3and a lower gear bracket4.

A hole part2aof the lower cam bracket2is a coupling point (i.e. center of oscillation of the lower plate9) of the lower cam bracket2relative to the cam unit5. The hole part2aconstitutes a lower plate oscillation shaft line C1that extends in a horizontal direction (arrow R direction). Arrow U and arrow F also indicate directions in the figures. A hole part1aof an upper cam bracket1is a coupling point (i.e. center of oscillation of the upper plate8). The hole part1aconstitutes an upper plate oscillation shaft line C2that is parallel to the lower plate oscillation shaft line C1.

A coupling point of the lower gear bracket4relative to the gear unit6(positioned on the right side ofFIG. 1) is positioned on the lower plate oscillation shaft line C1, and a coupling point of the upper gear bracket3relative to the gear unit6is positioned on the upper plate oscillation shaft line C2.

The cam unit5and the gear unit6cooperatively support the lower plate9to oscillate about the lower plate oscillation shaft line C1and cooperatively support the upper plate8to oscillate about the upper plate oscillation shaft line C2.

The upper plate8has a pair of left/right ear parts8athat project outward therefrom. Further, the lower plate9also has a pair of left/right ear parts9athat project outward therefrom.

The upper cam bracket1has a flat surface part1cin which a pair of front/rear attachment hole parts1ais formed. The flat surface part1cis fixed to an upper surface of the left ear part8aby a fastening screw10. The lower cam bracket2has a flat surface part2cin which a pair of front/rear attachment hole parts2bis formed. The flat surface part2cis fixed to a lower surface of the left ear part9aby the fastening screw10.

The upper gear bracket3has a flat surface part3cin which a pair of front/rear attachment hole parts3bis formed. The flat surface part3cis fixed to an upper surface of the right ear part8aby the fastening screw10. The lower gear bracket4has a flat surface part4cin which a pair of front/rear attachment hole parts4bis formed. The flat surface part4cis fixed to a lower surface of the right ear part9aby the fastening screw10.

The cam unit5according to the first embodiment of the present invention functions as a unit for restricting oscillation of the upper cam bracket1and the lower cam bracket2at a predetermined angle by increasing torque at the predetermined angle during relative oscillation between the upper cam bracket1and the lower cam bracket2.

Further, the gear unit6functions as a unit that synchronizes the rotation of the lower gear bracket4about the lower plate oscillation shaft line C1(the angle of the rotation is hereinafter referred to as “first oscillation angle θ1”) and the rotation of the upper gear bracket3about the upper plate oscillation shaft line C2(the angle of the rotation is hereinafter referred to as “second oscillation angle θ2”).

As illustrated inFIGS. 3A and 3B, the cam unit5has a first cam mechanism50A and a second cam mechanism50B arranged inside a hinge cover56. The first cam part50A includes, for example, a first cam portion (constituted by a spring54, a first cam shaft55A, and cam plates52,53) and a first cam81. Further, the second cam part50B includes, for example, a second cam portion (constituted by the spring54, a first cam shaft55B, and the cam plates52,53) and a second cam82.

The first cam shaft55A included in the first cam mechanism50A is arranged in the hinge cover56to match the upper plate oscillation shaft line C2. By inserting the first cam shaft55A through a bore part52aof the cam plate52, a bore part53aof the cam plate53, and a bore part57aof a hinge cap57(which is to be a lid body of the hinge cover56), the first cam shaft55A is rotatably supported by the plates52,53, and the hinge cap57.

The spring54is arranged between the cam plate53and the hinge cap57. Further, the first cam81is arranged between the cam plate52and the cam plate53.

The first cam shaft55A includes a first intermediate key part55ahaving an oval-shaped cross section. The first intermediate key part55ais to engage an oval-shaped engagement bore81aof the first cam81a. In a mounted state, the first intermediate key part55aengages the engagement bore81a. Thereby, the first cam shaft55A and the first cam81integrally rotate with each other.

The first cam shaft55A includes a second intermediate key part55bformed at its right end part inFIG. 3B. In a state where the cam unit5is assembled, the second intermediate key55bis configured to project in a right direction of the hinge cap57. The upper cam bracket1is mounted to the second intermediate key part55b(projecting from the hinge cap57) by way of a washer58and a sleeve59.

An oval-shaped bore1ais formed in an end part of the upper cam bracket1. The second intermediate cam part55bof the first cam shaft55A is configured to engage the oval-shaped bore1aof the upper cam bracket1. Thus, the upper cam bracket1integrally rotates with the first cam shaft55A by engaging the second intermediate key part55bwith the oval-shaped bore1a. It is to be noted that a tip part of the second intermediate part55bis fixed to the upper cam bracket1by caulking.

As illustrated in an enlarged view ofFIG. 13, the first cam portion is constituted by a peak part and a valley part formed in the cam plate52, the cam plate53, and the first cam81, respectively. More specifically, the cam plate52includes a pair of peak parts52c,52dand a pair of valley parts52g,52h. Further, the cam plate53includes a pair of peak parts53c,53dand a pair of valley parts53g,53h.

Further, the first cam81has a pair of peak parts81d,81eand a pair of valley parts81h,81iformed on a surface facing the cam plate52and a pair of peak parts81b,81cand a pair of valley parts81f,81gformed on a surface facing the cam plate53.

Each of the cam plate52, the cam plate53, and the first cam81has the pair of peak parts arranged at an interval of 180 degrees. Likewise, each of the cam plate52, the cam plate53, and the first cam81has the pair of valley parts arranged at an interval of 180 degrees. Further, adjacent peak parts and valley parts are arranged at an interval of 90 degrees.

Further, the peak parts52c,52d, and the valley parts52g,52hof the cam plate52and the peak parts53c,53d, the valley parts53g,53hof the cam plate53are arranged to have the same phase with each other. That is, the peak part52cand the peak part53c, the peak part52dand the peak part53d, the valley part52gand the valley part53g, and the valley part52hand the valley part53hare configured to face each other, respectively.

Next, the second cam mechanism50B is described. The second cam mechanism50B has substantially the same configuration as the configuration of the first cam mechanism50A.

As illustrated inFIG. 3B, the second cam shaft55A included in the second cam mechanism50B is arranged in the hinge cover56to match the lower plate oscillation shaft line C1. By inserting the second cam shaft55B through a bore part52bof the cam plate52, a bore part53bof the cam plate53, and a bore part57bof the hinge cap57(which is to be a lid body of the hinge cover56), the second cam shaft55B is rotatably supported by the plates52,53, and the hinge cap57.

The spring54is arranged between the cam plate53and the hinge cap57. Further, the second cam82is arranged between the cam plate52and the cam plate53.

Similar to the first cam shaft55A, the second cam shaft55B includes the first intermediate key part55ahaving an oval-shaped cross section. The first intermediate key part55ais to engage an oval-shaped engagement bore82aof the second cam82a. In a mounted state, the first intermediate key part55aengages the engagement bore82a. Thereby, the second cam shaft55band the second cam82integrally rotate with each other.

Further, the second cam shaft55B includes the second intermediate key part55bformed at its right end part inFIG. 3B. In a state where the cam unit5is assembled, the second intermediate key55bis configured to project in a right direction of the hinge cap57. The lower cam bracket2is mounted to the second intermediate key part55b(projecting from the hinge cap57) by way of the washer58and the sleeve59.

An oval-shaped bore1ais formed in an end part of the lower cam bracket2. The second intermediate cam part55bof the second cam shaft55B is configured to engage the oval-shaped bore1aof the lower cam bracket2. Thus, the lower cam bracket2integrally rotates with the second cam shaft55B by engaging the second intermediate key part55bwith the oval-shaped bore2a. It is to be noted that a tip part of the second intermediate part55bis fixed to the lower cam bracket2by caulking.

Similar to the first cam portion, the second cam portion is constituted by a peak part and a valley part formed in the cam plate52, the cam plate53, and the second cam82, respectively. More specifically, as illustrated in the enlarged view ofFIG. 13, the cam plate52includes a pair of peak parts52e,52fand a pair of valley parts52i,52j. Further, the cam plate53includes a pair of peak parts53e,53fand a pair of valley parts53i,53j.

Further, the second cam82has a pair of peak parts82d,82eand a pair of valley parts82h,82iformed on a surface facing the cam plate52and a pair of peak parts82b,82cand a pair of valley parts82f,82gformed on a surface facing the cam plate53.

In the second cam portion, each of the cam plate52, the cam plate53, and the second cam82has the pair of peak parts arranged at an interval of 180 degrees. Likewise, each of the cam plate52, the cam plate53, and the second cam82has the pair of valley parts arranged at an interval of 180 degrees. Further, adjacent peak parts and valley parts are arranged at an interval of 90 degrees. Further, the peak part52eand the peak part53e, the peak part52fand the peak part53f, the valley part52iand the valley part53i, and the valley part52jand the valley part53jare configured to face each other, respectively.

In the cam unit5according to an embodiment of the present invention, the first cam portion constituting the first cam mechanism50A is configured the same as the second cam portion constituting the second cam mechanism50B. Further, the first cam81is configured the same as the second cam82.

In the hinge apparatus D1for an electronic device according to the first embodiment of the present invention, the upper plate8can be rotated 360 degrees relative to the lower plate9from the closed state illustrated inFIG. 1. However, among the pair of upper and lower cam mechanisms50A,50B of the cam unit5, the cam mechanism50A of the upper side is assigned with the rotation of 180 degrees whereas the cam mechanism of the lower side is assigned with the rotation of 180 degrees. In a state where the upper and lower plates8,9are closed or in a state where the upper plate8is rotated 360 degrees and installed on a rear side of the lower plate9(rear installed state), the cam unit5retains the upper and lower plates8,9in the aforementioned states by engaging the peak parts and the valley parts of the first and second cam portions and increasing the torque.

The cam unit5according to this embodiment of the present invention has two peak parts and valley parts arranged in portions of the first cam mechanism50A where the cam plate52, the cam plate53, and the first cam81are formed, respectively. Likewise, the cam unit5according to this embodiment of the present invention has two peak parts and valley parts arranged in portions of the second cam mechanism50B where the cam plate52, the cam plate53, and the first cam81are formed, respectively. However, the numbers of peak parts and valley parts to be formed in the first and the second cam mechanisms50A,50B is not limited to those described above, and may be arbitrarily changed according to, for example, the purpose of the hinge apparatus D1for an electronic device.

Next, the gear unit6is described with reference toFIGS. 4A and 4B.

The gear unit6has a configuration including, for example, a pair of first (upper) and second (lower) gear shafts61A,61B, a pair of gears62A,62B, a pair of gear shafts63A,63B, supporting plates64,66, a middle plate65, a riveting plate67, a gear cover68, and a gear cap69.

The first gear shaft61A on the upper side is positioned on the upper plate oscillation shaft line C2, and the second gear shaft61B on the lower side is positioned on the lower plate oscillation shaft line C1. The support plate64includes a pair of upper and lower engagement bores64ato which the end parts of the first and second gear shafts61A,61B are rotatably engaged. Further, the support plate64includes bore parts64bformed in an intermediate area (in the vertical direction) between the engagement bores64a. Minor diameter parts formed on one end of the pair of gear shafts63A,63B are to be engaged to the bore parts64b.

The middle plate65includes bore parts65ato which the gear shafts63A,63B are inserted. The support plate66includes a pair of hole parts66ato which end parts of the gear shaft70A,70B can be inserted. Further, the gear cap69includes a recess part (for installing the support plate66) and a pair of hole parts69a(to which end parts of the gear shafts70A,70B are inserted) formed on its end surface facing the gear cover68.

After the tip parts of the gear shafts63A,63B are inserted in center bores62aof the pair of upper and lower gears62A,62B and the bore parts65aof the middle plate65, the tip parts of the gear shafts63A,63B are further inserted to the bore parts64bof the support plate64. Then, the riveting plate67is fixed to the end parts of the gear shafts63A,63B projecting from the support plate64by caulking, to thereby constitute a sub-assembly (sub-ASSY).

Then, the sub-assembly is inserted to the gear cover68; the plate66is contacted to the end parts of engagement bore parts of the first and second gear shafts61A,61B; and the gear cap69is engaged with an opening part of the gear cover68.

After the pair of upper and lower gear shafts70A,70B are inserted to the holes3a,4aof the upper and lower gear brackets3,4, the hole parts69aof the gear cap69, and the hole parts66aof the support plate66, the upper and lower gear shafts70A,70B are engaged with the engagement bore parts61aof the first and second gear shafts61A,61B.

Further, in the gear unit6according to this embodiment of the present invention, the gear shaft70A is configured to match the upper plate oscillation shaft line C2, and the gear shaft70B is configured to match the lower plate oscillation shaft line C1. Further, each of the gear shafts70A,70B includes an insertion hole70apenetrating its center. The function of the insertion hole70ais described below.

As described above, the gear unit6is formed by engaging the pair of gear shafts70A,70B with the first and second gear shafts61A,61B. The gear unit6integrally rotates the gear shaft70A and the first gear shaft61A and integrally rotates the gear shaft70B and the first gear shaft61B.

Further, the gear part61bof the first gear shaft61A meshes with the gear62A, and the gear part61bof the second gear shaft61B meshes with the gear62B. Further, the gear62A meshes with the gear62B. The gears62A,62B along with the gear parts61bof the first and second gear shafts61A,61B constitute the gear mechanism taught in the claims.

Therefore, by rotating and urging the upper gear bracket3(joined to the gear shaft70A) in one direction, the gear unit6rotates the lower cam bracket2(joined to the gear shaft70B) in the other direction (direction opposite to the rotating direction of the upper gear bracket3).

Further, the gear ratio between the gear parts61bof the first and second gear shafts61A,61B of the gear unit6and the gears62A,62B is set, so that the rotation of the upper gear bracket3and the rotation of the lower gear bracket4are synchronized (so that rotation can be performed with the same angular velocity).

Further, the upper gear bracket3and the lower gear bracket4are restricted from uniquely rotating (oscillating) by being meshed and coupled to each of the gear parts61band the gears62A,62B. The upper gear bracket3is fixed to the upper plate8. The lower gear bracket4is fixed to the lower plate9. Thereby, the gear unit6rotates the lower and upper cam brackets2,4in synchronization along with providing a function of a rotation prevention mechanism that prevents the lower and upper cam brackets2,4from oscillating relative to each other.

Further, as described above, the upper plate8is fixed to the upper cam bracket1of the cam unit5, and the lower plate9is fixed to the lower cam bracket2of the cam unit5. Accordingly, when the cam unit5is rotated to a predetermined rotation angle for generating torque in a case where the upper plate8and the lower plate9are rotated in synchronization, the rotation of the upper plate8and the lower plate9is restricted by the increase of the torque.

Accordingly, with the hinge apparatus D1for an electronic device according to the first embodiment of the present invention, the upper plate8and the lower plate9can be rotated in synchronization by the gear unit6, and the rotation of the upper plate8and the lower plate9can be restricted to a desired rotation angle by the cam unit5.

Next, the insertion bores70athat are formed in the gear shafts70A,70B are described. The insertion bore70afunctions as a wiring insertion bore to which a core (wiring)7is inserted as illustrated inFIGS. 1 and 2. As illustrated inFIG. 8, the hinge apparatus D1constituted by the cam unit5and the gear unit6has the upper plate8fixed to an upper case of an electronic apparatus S which is to be the application target (seeFIG. 6) and the lower plate9fixed to a lower case12of the electronic apparatus S. Electronic components are mounted to each of the upper and lower cases11,12. The cord7has a function of electrically connecting an electronic circuit mounted on the upper case11to an electronic circuit mounted on the lower case12.

Thereby, although the cord7is to be arranged between the upper case11and the lower case12, the cord7is preferred not to be exposed to the outside from an aspect of design and is liable of being pulled out in a case where, for example, external force is applied.

However, with the first embodiment of the present invention, the cord7can be connected between the upper case11and the lower case12inside the gear unit6(gear cover68) by forming the insertion bores70ain the gear shafts70A,70B and inserting the cord7to the insertion bores70aas illustrated inFIGS. 5A and 5B. With this configuration, the appearance of the electronic apparatus S can be improved and it can be prevented from being pulled out.

Next, a hinge operation of the hinge apparatus D1for an electronic device according to the first embodiment of the present invention is described.

In a case where the upper plate8is closed (closed state) relative to the lower plate9(as illustrated inFIGS. 7,9A,9B, and9C), the upper case11of the electronic apparatus S is also closed (closed state) relative to the lower case12of the electronic apparatus S (as illustrated inFIGS. 8,10A,10B,10C,11A, and14A).

Further, in the peak parts and valley parts of the first and second cam portions included in the first and second cam mechanisms50A,50B, each of the peak parts and the valley parts of the first cam81and the cam plate52are engaged and the each of the peak parts and the valley parts of the second cam82and the cam plate52are engaged in this closed state as illustrated inFIG. 14B. Therefore, in the closed state, the hinge apparatus D1for an electronic device is in a state where the torque is increased and where the rotation of the upper case11(upper plate8) and the lower case12(lower plate9) is restricted.

It is to be noted thatFIGS. 14B,15B,16B, and17B are developed views of the cams of the first and second cam portions included in the first and second cam mechanisms50A,50B. Further, inFIG. 14Cillustrating a rear surface of the cam unit5, each of the cam parts indicated with letters A-D corresponds to letters A-D illustrated on the left side of the developed views ofFIGS. 14B,15B,16B, and17B.

In a case where the user opens the upper case11from the closed state by using a force greater than or equal to the above-described torque generated by the hinge apparatus D1, the upper case11begins a rotation (lid opening) movement relative to the lower case12. In this case, the upper case11can be steadily opened relative to the lower case12because the rotation of the upper gear bracket3and the lower gear bracket4are synchronized by the function of the gear unit6included in the hinge apparatus D1for an electronic device.

Further, by rotating the upper case11(upper plate8) relative to the lower case12(lower plate9), the engagement of the peak parts and the valley parts between the first cam81and the cam plate52and the engagement of the peak parts and the valley parts between the second cam82and the cam plate52can be released as illustrated inFIG. 15B. Thereby, the engagement of all of the peak parts and valley parts of the first and second cam portions can be released. The rotation of the upper case11(upper plate8) relative to the lower case12(lower plate9) can be performed smoothly.

FIGS. 16A,16B illustrate a state where the upper case11(upper plate8) is rotated 90 degrees or more relative to the lower case12(lower plate9). In this state also, the engagement of all of the peak parts and valley parts of the first and second cam portions remains released.

FIGS. 11B and 17Aillustrate a state where the upper case11(upper plate8) is rotated 360 degrees relative to the lower case12(lower plate9). In this sate, the upper case11and the lower case12are superposed and vertically inverted relative to the closed state.

Further, in the peak parts and valley parts of the first and second cam portions included in the first and second cam mechanisms50A,50B, each of the peak parts and the valley parts of the first cam81and the cam plate52are engaged and the each of the peak parts and the valley parts of the second cam82and the cam plate52are engaged in the rear installed state as illustrated inFIG. 14B. Therefore, in the rear installed state also, the hinge apparatus D1for an electronic device is in a state where the torque is increased and where the rotation of the upper case11(upper plate8) and the lower case12(lower plate9) is restricted.

Hence, with the above-described first embodiment of the hinge apparatus D1for an electronic device and the electronic apparatus S including the hinge apparatus D1, the following effects can be attained.

By positioning the cam unit5on the left side of the upper plate8and positioning the cam unit6on the right side inFIG. 1, mechanisms need not be provided at a center area of the upper case11in the horizontal direction and at a center area of the lower case12in the horizontal direction. Accordingly, electronic components such as a display a touch panel can be arranged in those center areas. Thus, a large size display or a touch panel can be used for the electronic apparatus S.

Further, in a case of using only one of the upper case11and the lower case12where the upper case11has an oscillation angle of 360 degrees relative to the lower case12, the upper case11can be chosen to be arranged in a rear installed position in which an outer surface of the upper case11is matched back to back with an outer surface of the lower case12. After the rear installed position is chosen, the user may then choose to use either an inner surface of the upper case11or an inner surface of the lower case12by having the inner surface of the upper or lower case11,12faced upward.

Further, in the cam unit5included in the hinge apparatus D1for an electronic device, the cam51having a cylindrical shape is sandwiched between the cam plate52and the cam plate53, and the outer peripheral surfaces of the cam plates52,53having elliptical shapes are supported by an inner peripheral surface of the hinge cover56. Thereby, the cam shafts55A,55B can be rotatably supported by the cam plates52,53. Thus, compared to supporting the cam shafts55A,55B with another configuration, the number of components can be reduced and size-reduction can be achieved.

Further, owing to the cord7being able to passed through the inside of the gear unit6by providing the insertion bores70ain the gear shafts70A,70B of the gear unit6according to the first embodiment of the present invention, the cord7can be prevented from being exposed to the outside. Thus, the cord7can electrically connect the upper and lower plates8,9while being appropriately protected.

Further, because the first and second gear shafts61A,61B include communicating parts61cprovided at the outer sides in the radial directions of the upper and lower plate oscillation shaft lines C1, C2(provided in the extending direction of the cord7). Therefore, even in a case where the upper plate8is oscillated relative to the lower plate9, each of the gear shafts61,61B can be prevented from interfering the cord7.

In the above-described first embodiment, the upper plate8and the lower plate9provide the function of a rotation prevention unit. In an alternative embodiment, a synchro-bar may be provided separately from the upper plate8for providing the function of the rotation prevention unit. Next, the alternative embodiment (second embodiment) is described.

FIG. 12illustrates the second embodiment of the present invention. It is to be noted that, inFIG. 12, like components are denoted by like reference numeral as those of the first embodiment (described withFIGS. 1-11) and are not further explained.

As illustrated inFIG. 12, in a hinge apparatus D2for an electronic device according to the second embodiment of the present invention, the upper cam bracket1and the upper gear bracket3are fixed to the upper case11made of resin, and the lower cam bracket2and the lower gear bracket4are fixed to the lower case12made of resin (not illustrated).

In the second embodiment of the present invention, instead of using the upper plate8and the lower plate9, a synchro-bar13is used for coupling the upper cam bracket1and the upper gear bracket3, and a synchro-bar14is used for coupling the lower cam bracket2and the lower gear bracket4.

The synchro-bars13,14are both formed of a plate-like member. In order to increase rigidity and facilitate attachment, both end parts of the synchro-bars13,14are bent and have a C-shaped cross section. The synchro-bars13,14are vertically arranged relative to the upper case11.

With the hinge apparatus D2for an electronic device according to the second embodiment of the present invention, a space can be formed at a center area between the cam unit5and the gear unit6because both the synchro-bars13,14are formed of a plate-like member. Accordingly, a large space for arranging liquid crystal displays or the like can be obtained.

In the second embodiment of the present invention, the synchro-bars13,14function as the rotation prevention unit. However, similar to the first embodiment, the upper plate8and the lower plate9may also be used to function as the rotation prevention unit by fixing the upper cam bracket1and the upper gear bracket3to the upper plate8and fixing the lower cam bracket2and the lower gear bracket4to the lower plate9.

For example, although the cam unit5is arranged on the left side whereas the gear unit6is arranged on the right side in the above-described embodiments, the cam unit5may be arranged on the right side whereas the gear unit6is arranged on the left side.

Although the term “left/right direction (horizontal direction)” is used for clarifying the positional relationship of the cam unit5and the gear unit6, the term “left/right direction (horizontal direction)” indicates the width direction of the above described electronic apparatus S or the hinge apparatuses D1, D2. Thus, “left side” indicates “left direction” and “right side” indicates “right direction” where the benchmark is the center of the electronic apparatus S and the hinge apparatus D1, D2in the width direction. Thus, positions can be defined even where the front/back direction does not match the vertical direction or where the front/rear direction does not match the horizontal direction.

The present international application is based on Japanese Patent Application Nos. 2010-157781 and 2011-148699 filed on Jul. 12, 2010 and Jul. 4, 2011, respectively, the entire contents of which are incorporated herein by reference.