Force sense generator

A force sense generator includes a rotatable circular plate having a rotation axis at a center of gravity; a motor that drives the circular plate to be rotated; a cam formed at a surface of the circular plate so as to surround the rotation axis; an anchor that is reciprocated along a linear trajectory that is perpendicular to the rotation axis of the circular plate; and a follower provided at the anchor and is moved along the cam, the cam being configured to include a first angle range and a second angle range such that the anchor is moved in opposite directions at different accelerations when the follower moves within the first angle range and when the follower moves within the second angle range, respectively, while the circular plate is rotated in one direction.

BACKGROUND OF THE INVENTION

The present invention relates to a force sense generator capable of causing to sense a force of a predetermined direction.

Description of the Related Art

Each of Patent Document 1 and Patent Document 2 discloses a force sense generator capable of make an operator sense a force of a predetermined direction by reciprocating an object with a predetermined weight.

The force sense generator of Patent Document 1 includes a flat plate cam in which a circular cam groove is formed, a rotator with a weight, and a cam follower that is rotated along the cam groove with the rotator. The rotator is connected at a rotation center provided inside the cam groove via a coil spring. The cam groove includes a curved surface in which a distance between the rotation center and the cam follower drastically becomes shorter, and a curved surface in which the distance gradually becomes longer. By rotating the rotator and the cam follower along the cam groove, asymmetrical accelerations are generated in a direction in which the coil spring is expanded and a direction in which the coil spring is compressed, and force sense is generated.

The force sense generator of Patent Document 2 includes an elliptical cam that is eccentrically rotated around a rotation axis, and a guide rod that is provided to move upward and downward at a position shifted from the rotation center of the elliptical cam. A lower end of the guide rod contacts a cam surface, which is a side surface of the elliptical cam, and an anchor is fixed at an upper end of the guide rod. When the elliptical cam is eccentrically rotated, asymmetry accelerations can be generated when the guide rod moves upward and when the guide rod moves downward to make an operator sense a force.

However, according to the structure of Patent Document 1, as the rotator with the weight is rotated with the cam follower, another acceleration is also generated in a direction different from a direction of a desired force to be sensed. As such acceleration causes vibration, it is difficult to make an operator extremely sense the force of one direction. For this problem, Patent Document 1 also discloses a structure in which another flat plate cam provided with a similar cam groove is overlapped and provided, while facing downward, to the above described flat plate cam, and a lower cam follower is rotated with a rotator with a weight same as that of the upper rotator in an opposite direction. With this configuration, it is described that the acceleration in the direction different from the direction of the desired force can be compensated. However, in such a structure, as two structures each including a flat plate cam, a rotator and a cam follower are necessary, and also a drive system that separately operates these structures is necessary, the structure becomes complicated. Further, in this structure, in order to compensate the undesired acceleration, it is necessary to move the upper and lower cam followers such that their rotation angles, other than the direction of the desired force to be sensed, are always accurately opposite from each other, and if these rotation angles are sifted even slightly, the acceleration in the direction different from the direction of the desired force to be sensed is not compensated, and vibration is generated.

Further, according to the structure of Patent Document 2, as the elliptical cam is eccentrically rotated, vibration is easily generated and it is difficult to make an operator extremely sense the force of one direction. For this problem, Patent Document 2 also discloses a structure in which an elliptical cam having a shape same as that of the above described elliptical cam is provided on a rotation axis coaxially provided with that of the above described elliptical cam, and is rotated in an opposite direction. With this configuration, it is described that a total sum of vectors of forces generated in directions different from the direction of the desired force to be sensed can be zero. However, in such a structure, as two elliptical cams and drive systems for driving the cams are necessary, the structure becomes complicated. Further, it is necessary to separately and accurately rotate the two elliptical cams in opposite directions, and if rotations of the two elliptical cams are shifted even slightly, the vectors of the forces in the directions other than the direction of the desired force to be sensed are not compensated and vibration is generated.

As such, according to the structures of Patent Document 1 and Patent Document 2, in order to effectively reduce generation of vibration, high-performance control for accurately rotating the two cam followers or the two elliptical cams in opposite directions is necessary.

SUMMARY OF THE INVENTION

The present invention is made in light of the above problems, and provides a force sense generator capable of making an operator extremely sense a force of one direction by a simple structure.

According to an embodiment, there is provided a force sense generator including a rotatable circular plate having a rotation axis at a center of gravity; a motor that drives the circular plate to be rotated; a cam formed at a surface of the circular plate so as to surround the rotation axis; an anchor that is reciprocated along a linear trajectory that is perpendicular to the rotation axis of the circular plate; and a follower provided at the anchor and is moved along the cam, the cam being configured to include a first angle range and a second angle range such that the anchor is moved in opposite directions at different accelerations when the follower moves within the first angle range and when the follower moves within the second angle range, respectively, while the circular plate is rotated in one direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A force sense generator of an embodiment is mounted on a personal digital assistant, a game device or the like, and is capable of making an operator sense a pseud force as if the operator is pulled in a certain direction. The generator is operated by linking with control of various game software such as a fishing game.

FIG. 1is a cross-sectional view illustrating an entire structure of a force sense generator1of an embodiment,FIG. 2is a perspective view of a force sense mechanism illustrated inFIG. 1, andFIG. 3is a plan view of the force sense mechanism illustrated inFIG. 1.

The force sense generator1illustrated inFIG. 1includes a case2, a force sense mechanism3, provided in the case2, that generates a pseudo force F in an X direction, and a motor4that drives the force sense mechanism3. In this embodiment, the motor4is supported in the case2, and the force sense mechanism3is provided at a lower side of the motor4in a Z direction. The force sense mechanism3is configured to convert a rotational motion of a cam to a reciprocating motion of an anchor on a linear line, and generate the force F that is sensed in one direction by controlling accelerations of the anchor in a forward motion and a backward motion to be asymmetry.

Specifically, as illustrated inFIG. 2, the force sense mechanism3includes a circular plate6capable of being rotated around a rotation shaft5(rotation axis), which is rotated by the motor4, as a center. The circular plate6has a completed round shape, there is almost no mass deviation, and the rotation shaft5is set to be a center of gravity. A cam groove7that is formed to surround the rotation shaft5is formed at one surface of the circular plate6, at a lower plane6ahere.

An anchor9is provided at a lower side of the circular plate6. The anchor9is guided by inner walls2a,2aformed inside the case2to be movable only along a tracing of a linear line G, and is regulated not to move in directions other than the linear line direction. A pin-like follower8is fixed to the anchor9near a left-side end portion9ainFIG. 3, and the follower8slides in the cam groove7.

The linear line G means a moving tracing that passes on a center O of the rotation shaft5in the circular plate6and also extends in a direction perpendicular to the rotation shaft5. The follower8moves on the linear line G. The linear line G matches a center line that divides a width of the anchor9in a Y direction and extends in the X direction. Thus, the anchor9that reciprocates in the X direction is configured such that mass deviation in the Y direction is not generated.

The anchor9has a long shape (rectangular shape) and its longer direction is directed in the X direction, which is a moving direction. As illustrated inFIG. 3, the follower8is provided near the end portion9aat a left-side of the anchor9. As illustrated inFIG. 4AtoFIG. 4C, the follower8only moves in an area at a left-side of the rotation shaft5, and an end portion9bof the anchor9at a right-side only moves in an area at a right-side of the rotation shaft5. In such a structure, it is possible to make the anchor9relatively large to increase its weight, and further, the anchor9that is reciprocated in the X direction can be prevented from largely protruding from a projection area of the circular plate6. Further, as illustrated inFIG. 4AtoFIG. 4C, it is possible to configure a structure in which the reciprocating anchor9does not protrude from the projection area of the circular plate6.

When the circular plate6is rotated, the cam groove7is rotated in accordance with the ration of the circular plate6, and the follower8inserted in the cam groove7is reciprocated on the linear line G. With this, the anchor9is reciprocated in the X direction and its opposite direction.

At this time, by controlling acceleration when the anchor9is moved forward in the X direction (forward movement) and acceleration when the anchor9is moved backward in the opposite direction (backward movement) to be asymmetry, it is possible to make an operator sense the force F of one direction. In this embodiment, the acceleration when the anchor9is moved forward in a left-direction in the drawing is larger than the acceleration when the anchor9is moved backward in a right-direction in the drawing, and these movements are repeated.

With this, it is possible to make the operator sense the pseud force F in the X direction. Further, in this embodiment, as the anchor9is limited to only linearly move, and the circular plate6which hardly has mass deviation is rotated around its center of gravity as a center without rotating the anchor9, acceleration or a force is not generated in directions other than the direction of the desired force F to be sensed by the operator. Thus, almost no vibration is generated. Therefore, it is possible to make the operator extremely sense only the force F of the X direction.

In this embodiment, such accelerations at a forward movement and a backward movement of the follower8and the anchor9are defined by a shape of the cam groove7.FIG. 3illustrates an example of a structure of the cam groove7of the embodiment. The cam groove7illustrated inFIG. 3is configured such that the follower8and the anchor9are reciprocated twice every time the cam groove7is rotated once (every time the circular plate6is rotated once). InFIG. 3, an angle range of the cam groove7in which the follower8and the anchor9are moved forward in the left-direction in the drawing is assumed as a first angle range θ1, and an angle range of the cam groove7in which the follower8and the anchor9are moved backward in the right-direction in the drawing is assumed as a second angle range θ2. Here, it is defined that θ1<θ2and θ1+θ2=180 degrees. In other words, when the follower8moves along the cam groove7within the first angle range θ1, the follower8and the anchor9are moved forward in the left-direction in the drawing, and when the follower8moves along the cam groove7within the second angle range θ2, the follower8and the anchor9are moved backward in the right-direction in the drawing.

The cam groove7is configured by a curve such that acceleration is drastically increased within a short period in the first angle range θ1(forward movement) and a curve such that acceleration is gradually decreased within a long period in the second angle range (backward movement). In other words, while the circular plate6is rotated, a rotation angle necessary for moving the follower8for a predetermined distance in a radial direction, where the center is the rotation shaft5, is sufficiently smaller for the first angle range θ1than for the second angle range θ2.

Here, the first angle range θ1(forward movement) and the second angle range θ2(backward movement) are smoothly continued. According to the cam groove7configured as such, variation of the distance between the follower8and the center O of the rotation shaft5is a movement amount of the anchor9. At this time, when assuming that the weight of the anchor9as “M”, an average acceleration of the anchor9in the first angle range θ1as “α1”, and an average acceleration of the anchor9in the second angle range θ2as “α2”, it is possible to make an operator sense a force of approximately F=Mα1−Mα2in the X direction every time the follower8and the anchor9are reciprocated once.

Next, an operation of the force sense generator1configured as such is described.FIG. 4AtoFIG. 4Care views for describing the operation of the force sense mechanism3of the embodiment.FIG. 4AtoFIG. 4Cillustrate statuses when the circular plate6is rotated in a direction illustrated by an arrow.FIG. 4Aillustrates a status in which the follower8is positioned at a start point of the first angle range θ1.FIG. 4Billustrates a status in which the follower8is positioned at a start point of the second angle range θ2(at an end point of the first angle range θ1).FIG. 4Cillustrates a status in which the follower8is positioned at an end point of the second angle range θ2(at a start point of the next first angle range θ1).

When the circular plate6is rotated by the motor4in the direction of the arrow from the status illustrated inFIG. 4A, the cam groove7is rotated in the same direction in accordance with the ration of the circular plate6, to the status illustrated inFIG. 4Cafter passing through the status illustrated inFIG. 4B. The anchor9is positioned at a rightmost position in the status illustrated inFIG. 4A. During the status illustrated inFIG. 4Ato the status illustrated inFIG. 4B, the follower8is moved forward with the anchor9in the left-direction in the drawing while sliding in the first angle range θ1of the cam groove7. At this time, the follower8and the anchor9are moved in the X direction within a short period by a large acceleration. The anchor9is positioned at a leftmost position in the status illustrated inFIG. 4B. Then, during the status illustrated inFIG. 4Bto the status illustrated inFIG. 4C, the follower8is moved backward with the anchor9in the right-direction in the drawing while sliding in the second angle range θ2of the cam groove7. At this time, the follower8and the anchor9are moved in the opposite direction of the X direction by a period longer than that in the first angle range θ1by acceleration smaller than that in the first angle range θ1. The anchor9is positioned at the rightmost position in the status illustrated inFIG. 4C.

As such, when the circular plate6is rotated from the status illustrated inFIG. 4Ato the status illustrated inFIG. 4C, the circular plate6is rotated for 180 degrees, and the follower8and the anchor9are reciprocated once. Further, when the circular plate6is rotated for further 180 degrees, the follower8and the anchor9are reciprocated once more. At this time, the follower8and the anchor9are moved forward in the X direction by a larger acceleration within a short period, and are moved backward in an opposite direction of the X direction by acceleration smaller than that by a longer period. While continuously rotating the circular plate6by the motor4, a reciprocating motion in which the follower8and the anchor9are reciprocated twice per one rotation of the circular plate6is repeated. With this, it is possible to make an operator sense the force F in the X direction.

In particular, in this embodiment, as described above, almost no vibration is generated. Thus, it is possible to make the operator extremely sense only the force F in the X direction. Further, as the almost no vibration is generated, different from the conventional structure, it is unnecessary to provide a structure in which two same structures are aligned to be rotated in opposite directions for reducing vibration, and a device structure can be simplified.

Although it is described in this embodiment a case in which the circular plate6is rotated in the direction of the arrow ofFIG. 3, this is not limited so. The circular plate6may be rotated in an opposite direction of the direction of the arrow ofFIG. 3. With this, it is possible to make an operator sense a force in an opposite direction of the X direction. Further, by providing a plurality of the force sense generators1of the embodiment in different directions, it is possible to make the operator sense a force of a desired direction.

Further, although an example is illustrated as the cam groove7illustrated inFIG. 3in which a combination of the first angle range θ1at the forward movement and the second angle range θ2at the backward movement is repeated twice to form one circle, this is not limited so. Angles of the first angle range θ1and the second angle range θ2can be independently selectable. In such a case, the cam groove7may be formed such that a combination of the first angle range θ1and second angle range θ2is repeated three times to form one circle, for example. When the repeated number of the combinations of the first angle range θ1and the second angle range θ2is increased, the reciprocating time of the follower8and the anchor9per rotation of the circular plate6can be increased. Further, the cam groove7may be formed such that the combination of the first angle range θ1and the second angle range θ2forms one circle.

Further, although it is described in this embodiment an example in which the cam groove7as illustrated inFIG. 3is formed as a cam formed at one surface of the circular plate6, this is not limited so. For example, as illustrated inFIG. 5, a protrusion10, having a curve same as that of the cam groove7illustrated inFIG. 3, may be formed at the surface plane6aof the circular plate6to protrude downward to function as a cam. In such a case, as illustrated inFIG. 5, a spring11that forces the follower8to contact an outline of the protrusion10as the cam, may be provided to the anchor9. With this configuration as well, when the circular plate is rotated in a direction of the arrow, for example, the follower8and the anchor9are reciprocated by the motor4similarly as the above described embodiment. Thus, it is possible to make an operator extremely sense the force F in the X direction.

According to the force sense generator of the embodiment, the follower is reciprocated on the linear line with the anchor by rotation of the cam. As the cam is formed such that accelerations are different within the first angle range in which the follower and the anchor are moved forward, and the second angle range in which the follower and the anchor are moved backward. Thus, it is possible to make an operator sense a force corresponding to a difference between the accelerations of the forward movement and the backward movement of the follower in the direction of the linear line. As the anchor is regulated to move only on the linear line, and the circular plate which hardly has mass deviation is rotated around its center of gravity as a center, acceleration or a force is not generated in directions other than the direction of the desired force to be sensed by the operator, and almost no vibration is generated. Thus, it is possible to make the operator extremely sense a force of only one direction. Further, as almost no vibration is generated, different from the conventional structure, it is unnecessary to provide a structure in which two same structures are aligned to be rotated in opposite directions for reducing vibration, and a device structure can be simplified.

According to the force sense generator of the embodiment, a shape of the cam may be configured such that an angle necessary to move the follower for a predetermined distance in a radial direction of the circular plate is smaller for the first angle range than for the second angle range.

According to the force sense generator of the embodiment, the follower may be provided at one end portion of the anchor in a moving direction, and the follower may be configured to move only at one side of the rotation axis, and another end portion of the anchor is moved only at another side of the rotation axis.

According to the force sense generator of the embodiment, even when the anchor is reciprocated, the moving tracing of the anchor does not largely protrude from an outline of the circular plate, the device can be made into small size.

According to the force sense generator of the embodiment, the cam may include a plurality of combinations, each including the first angle range and the second angle range in this order.

According to the force sense generator of the embodiment, acceleration or a force is not generated in directions other than the direction of the desired force to be sensed by the operator. Thus, almost no vibration is generated, and it is possible to make the operator extremely sense the force of only one direction. Further, as almost no vibration is generated, different from the conventional structure, it is unnecessary to provide a structure in which two same structures are aligned to be rotated in opposite directions for reducing vibration, and a device structure can be simplified.

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