Portable information device and hinge device

1. A portable information device, comprising:

a first chassis;

a second chassis adjacent to the first chassis;

a hinge device that relatively rotatably connects the first chassis and the second chassis, while gradually changing a relative angle between their plane directions between a 0-degree position in which the first chassis and the second chassis are stacked to overlap with one another in their plane directions and a 180-degree position in which the first chassis and the second chassis are arranged in a direction perpendicular to their plane directions; wherein

the hinge device comprises:

a first base plate fixed to the first chassis;

a second base plate fixed to the second chassis;

a first link plate that overlaps with the first base plate, where a first end portion of the first link plate is relatively rotatably connected to the first base plate through a first shaft;

a second link plate that overlaps with the second base plate, where a first end portion of the second link plate is relatively rotatably connected to the second base plate through a second shaft;

a coupling plate having:

a first end portion of the coupling plate relatively rotatably connected to a second end portion of the first link plate through a third shaft; and

a second end portion of the coupling plate relatively rotatably connected to a second end portion of the second link plate through a fourth shaft;

a first torque generating part that generates a rotation torque in relative rotation of the first base plate and the first link plate by sliding resistance between the first base plate and the first link plate; and

a second torque generating part that generates a rotation torque in relative rotation of the second base plate and the second link plate by sliding resistance between the second base plate and the second link plate,

when the rotation angle between the first chassis and the second chassis is between the 0-degree position and a 20-degree position, torques generated by the first torque generating part and the second torque generating part are a first torque,

when the rotation angle between the first chassis and the second chassis is between a 120-degree position and a 140-degree position, the torques generated by the first torque generating part and the second torque generating part are a second torque,

when the rotation angle between the first chassis and the second chassis is the 180-degree position, the torques generated by the first torque generating part and the second torque generating part are a third torque, and

the second torque is greater than the first torque and the third torque is greater than the second torque.

2. The portable information device according to claim 1 , wherein

the first base plate has a first base arm projecting in an elastically deformable state toward the first link plate and is in slidable contact with the first link plate,

the first link plate has a first link arm projecting in an elastically deformable state toward the first base plate and is in slidable contact with the first base plate,

the second base plate has a second base arm projecting in an elastically deformable state toward the second link plate and is in slidable contact with the second link plate, and

the second link plate has a second link arm projecting in an elastically deformable state toward the second base plate and is in slidable contact with the second base plate.

3. The portable information device according to claim 2 , wherein

the first torque generating part generates the first torque, second torque, and third torque, by the change, according to the rotation angle, in a sliding distance of the first base arm with respect to the first link plate and a sliding distance of the first link arm with respect to the first base plate, per unit angle when the first chassis and the second chassis rotate, and

the second torque generating part generates the first torque, second torque, and third torque, by the change, according to the rotation angle, in a sliding distance of the second base arm with respect to the second link plate and a sliding distance of the second link arm with respect to the second base plate, per the unit angle.

4. The portable information device according to claim 3 , wherein

a torque whose magnitude is adjusted by the change, according to the rotation angle, in the sliding distance of the first base arm per the unit angle, is a first adjusting torque,

a torque whose magnitude is adjusted by the change, according to the rotation angle, in the sliding distance of the first link arm per the unit angle, is a second adjusting torque,

a torque whose magnitude is adjusted by the change, according to the rotation angle, in the sliding distance of the second base arm per the unit angle, is a third adjusting torque, and

a torque whose magnitude is adjusted by the change, according to the rotation angle, in the sliding distance of the second link arm per the unit angle, is a fourth adjusting torque,

the torque generated by the first torque generating part, by the change in the sliding distance of the first base arm per the unit angle, is set by a total value of the first and second adjusting torques, and

the torque generated by the second torque generating part, by the change in the sliding distance of the second base arm per the unit angle, is set by a total value of the third and fourth adjusting torques.

5. The portable information device according to claim 4 , wherein

the first adjusting torque is smaller than the second adjusting torque when the rotation angle is at least between the 0-degree position and the 20-degree position, while the first adjusting torque is greater than the second adjusting torque when the rotation angle is at least between the 120-degree position and the 180-degree position, and

the third adjusting torque is smaller than the fourth adjusting torque when the rotation angle is at least between the 0-degree position and the 20-degree position, while the third adjusting torque is greater than the fourth adjusting torque when the rotation angle is at least between the 120-degree position and the 180-degree position.

6. The portable information device according to claim 1 , wherein the hinge device further comprises:

a first gear arm that includes:

a first end portion of the first gear arm that is relatively rotatably connected to the first base plate through a fifth shaft; and

a second end portion of the first gear arm that is relatively rotatably connected to the coupling plate through a sixth shaft,

wherein the first gear arm further includes a first gear around the sixth shaft; and

a second gear arm that includes:

a first end portion of the second gear arm that is relatively rotatably connected to the second base plate through a seventh shaft; and

a second end portion of the second gear arm that is rotatably connected to the coupling plate through an eighth shaft,

wherein the second gear arm further includes a second gear engaged with the first gear around the eighth shaft.

7. A portable information device, comprising:

a first chassis;

a second chassis adjacent to the first chassis; and

a hinge device that relatively rotatably connects the first chassis and the second chassis, while gradually changing a relative angle between their plane directions between a 0-degree position in which the first chassis and the second chassis are stacked to overlap with one another in their plane directions and a 180-degree position in which the first chassis and the second chassis are arranged in a direction perpendicular to their plane directions, wherein

the hinge device has a torque generating part that generates a rotation torque in a rotation operation between the first chassis and the second chassis,

when the rotation angle between the first chassis and the second chassis is between the 0-degree position and a 20-degree position, a torque generated by the torque generating part is a first torque,

when the rotation angle between the first chassis and the second chassis is between a 120-degree position and a 140-degree position, the torque generated by the torque generating part is a second torque,

when the rotation angle between the first chassis and the second chassis is the 180-degree position, the torque generated by the torque generating part is a third torque, and

the second torque is greater than the first torque and the third torque is greater than the second torque.

8. A hinge device that relatively rotatably connects a first chassis and a second chassis of a portable information device while gradually changing a relative angle between their plane directions between a 0-degree position in which the first chassis and the second chassis are stacked to overlap with one another in their plane directions and a 180-degree position in which the first chassis and the second chassis are arranged in a direction perpendicular to their plane directions, the hinge device comprising:

a first base plate fixed to the first chassis;

a second base plate fixed to the second chassis;

a first link plate that overlaps with the first base plate, where a first end portion of the first link plate is relatively rotatably connected to the first base plate through a first shaft;

a second link plate that overlaps with the second base plate, where a first end portion of the second link plate is relatively rotatably connected to the second base plate through a second shaft;

a coupling plate having:

a first end portion of the coupling plate relatively rotatably connected to a second end portion of the first link plate through a third shaft; and

a second end portion of the coupling plate relatively rotatably connected to a second end portion of the second link plate through a fourth shaft;

a first torque generating part that generates a rotation torque in relative rotation of the first base plate and the first link plate by sliding resistance between the first base plate and the first link plate; and

a second torque generating part that generates a rotation torque in relative rotation of the second base plate and the second link plate by sliding resistance between the second base plate and the second link plate, wherein

torques generated by the first torque generating part and the second torque generating part, when the rotation angle between the first chassis and the second chassis is set between the 0-degree position and a 20-degree position, are a first torque,

torques generated by the first torque generating part and the second torque generating part, when the rotation angle between the first chassis and the second chassis is set between a 120-degree position and a 140-degree position, are a second torque,

torques to be generated by the first torque generating part and the second torque generating part, when the rotation angle between the first chassis and the second chassis is set to the 180-degree position, are a third torque, and

the second torque is greater than the first torque and the third torque is greater than the second torque.