Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Reexamination Certificate
1998-11-09
2001-02-20
Bucci, David A. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
C200S00600C, C345S161000
Reexamination Certificate
active
06189401
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrical joystick controller.
2. State of the Art
It is sometimes required that, when the joystick control lever reaches a predetermined position after displacement along one of its major axes, that it can be displaced further in the same direction but only upon application of a significantly increased force (i.e. the operator experiences significantly increased resistance when moving the control lever beyond the predetermined position). In one known joystick controller, this is achieved in that a bush, carried on the joystick lever and spring-biased against a fixed cam surface, reaches a more steeply-inclined portion of the cam surface. A problem with this is that the position of the joystick lever, along the respective major axis, at which the bush engages the steeper portion of the cam, tends to vary according to the position of the joystick lever along its other, orthogonal major axis. Thus, the electrical signal from the joystick transducer arrangement for the one major axis, at which the increased resistance takes effect, varies depending on the position of the joystick lever along the other major axis. This is a problem for example where a threshold level of that signal is to be used to indicate that the operator has effected the additional displacement of the joystick lever, in order to initiate a particular control function of the apparatus or machine being controlled by the joystick device.
We have now devised a joystick controller which overcomes the above problem.
SUMMARY OF THE INVENTION
Thus, in accordance with the present invention, there is provided an electrical joystick controller, comprising a pivoted joystick lever, a main bush carried on the joystick lever and co-operating with a cam surface, a secondary bush carried on said lever and biased against an inclined surface of the main bush to correspondingly bias the main bush against the cam surface, and a stop against which a portion of the secondary bush abuts when said lever is pivoted through a predetermined angle parallel to a major axis of displacement, such that further displacement of said lever in the same direction causes said secondary bush to slide along said inclined surface of the main bush and displace against said bias.
The arrangement is therefore such that the operator experiences significantly increased resistance to movement of the joystick lever if he displaces the lever further in the same direction after the secondary bush has met the stop.
The stop may be made as a surface extending generally perpendicular to the respective major axis of movement of the joystick lever, and arranged such that the increased resistance to movement commences at substantially the same position of the lever parallel to that axis, regardless of the position to which it may have been moved along the other, orthogonal major axis of movement. Some compensation may be desirable, in order to fully achieve this result. Thus, once the joystick lever has been moved to its end position along the one major axis, then as it is moved along the other orthogonal axis, its main and therefore secondary bushes will be displaced further along the lever against the return bias: if the stop surface was perfectly straight, the result would be to force the lever slightly in the return direction along the one major axis. Preferably therefore, and in order to compensate for this, the stop surface comprises two portions which are inclined outwardly starting from the center of that surface.
The stop may be formed generally square in shape, such that the same increased-resistance effect is experienced for movements of the joystick lever in either direction along each of its two major axes of displacement.
In some circumstances, it is desirable to be able to move the joystick lever to a position of increased-resistance, or “overpress” position, along either major axis, and thereafter to be able to move the lever to an overpress position along the other major axis. In order to achieve this, preferably the above-described “overpress” arrangement is effective for one major axis of displacement, and the joystick controller includes a separate arrangement to provide the “overpress” feature on the second major axis of displacement. In particular, preferably the cam surface, with which the main bush co-operates, is provided on a cradle which pivots when the joystick lever is moved along the second major axis: a leading edge of the cradle slides on a stationary surface of the controller such that the cradle is displaced along the joystick lever (against the return bias); at a predetermined position, the latter surface includes an inclined portion or more steeply inclined portion, to provide increased resistance to movement along the respective major axis.
It is an advantage of the above-defined arrangements that the increased-resistance effect does not use the underside of the main bush, as in the known joystick mentioned above. Thus, excessive wear of the main cam surface of the main bush, particularly at a localised region corresponding to the respective direction of displacement, is avoided, such that the normal cam action, for returning the lever to its center or neutral position, is not compromised.
It is sometimes desirable to be able to temporarily lock the joystick lever at a predetermined angle of displacement, at least in one specific direction of displacement. We have now devised a simple but effective arrangement for achieving this.
Thus, in accordance with the present invention, there is provided an electrical joystick controller, comprising a pivoted joystick lever and a main bush carried on the joystick lever and biased against a co-operating a cam surface, said cam surface being formed with a recess into which a portion of said main bush locates at a predetermined position of displacement of said joystick lever.
A joystick controller in accordance with the invention may be provided with the increased-resistance or “overpress” feature, or with the temporary locking feature, or with both features combined. In the latter case, the temporary lock is preferably engaged at the end of the “overpress” travel in that particular direction.
In some circumstances, it is desirable to be able to lock the joystick lever temporarily as just described, at the end of a displacement along one major axis, and thereafter be able to move the joystick lever along the other, orthogonal major axis. For this purpose, preferably the cam surface, with which the main bush co-operates, is provided on a cradle of the form described above: the joystick lever can be displaced along the one major axis, until its main bush locks into the detenting recess formed in the cam surface of the cradle. However, the cradle pivots when the joystick lever is moved along the second major axis, as described above.
Embodiments of the present invention will now be described by way of examples only and with reference to the accompanying drawings.
REFERENCES:
patent: 3401574 (1968-09-01), Doolittle
patent: 3818154 (1974-06-01), Presentey
patent: 5176041 (1993-01-01), Meier et al.
patent: 5493931 (1996-02-01), Niskanen
patent: 5852953 (1998-12-01), Ersoy
patent: 1 268 251 (1968-05-01), None
patent: 4305282 A1 (1994-08-01), None
patent: 2107029A (1983-04-01), None
patent: 2155156A (1985-09-01), None
Atwell Anthony Keith
French Jeffrey
Bucci David A.
Gallagher Thomas A
Gordon David P.
Jacobson David S.
Joyce William C
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