Tripod head

Details Tripod head Tripod head

1999-08-25

2002-03-05

Chin-Shue, Alvin (Department: 3634)

Supports

Stand

To hold a particular article

C248S288510

Reexamination Certificate

active

06352228

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention concerns a tripod head with a universal joint, which has a ball joint swivelably and rotatably mounted in a bearing housing, wherein the universal joint is arranged between connecting points situated at oppositely facing ends of the tripod head, of which one is connected or connectable with a camera and the other with at least one tripod leg or similar mounting, wherein the ball joint, for restricting its swivelability to a swivelling motion about a swivelling axis running through the ball center point of the ball joint, is releasably connectable with an axial element.
Such a tripod head is known from U.S. Pat. No. 2,180,214 and from a prospectus of the firm EMO Optics, Wetzlar (1994). It has an axial element which, in the operating position, is inserted into a bore hole of the ball joint and with another portion penetrates an opening of the bearing housing. To release the swivelability of the ball joint in any desired direction, the axial element can be removed from the ball joint and the bearing housing. In the operating position, the axial element inserted into the bore hole of the ball joint forms a swivel bearing which fixes the swivelability and the rotatability of the ball joint relative to the bearing housing in a way such that the ball joint is still swivelable only about the swiveling axis, and is moreover blocked. It is thereby possible to incline a camera fastened to the tripod head in a swiveling plane running exactly perpendicular to the swiveling axis, without there existing the danger of the camera inadvertently tipping about the center of the ball joint transverse to the swiveling plane, or rotating about an axis running in the swiveling plane through the center of the ball joint.
The previously known tripod has the disadvantage that the axial element, when removed from the bore hole of the ball joint, can easily become lost, so that the swivelability of the ball joint can then no longer be fixed. A further disadvantage consists in that the insertion of the axial element into the ball joint requires a certain adroitness, since the opening situated in the bearing housing must be brought precisely into alignment before inserting the axial element in the bore hole of the ball joint. Moreover, the axial element must be positioned exactly axially in relation to the opening and the bore hole, so that the axial element can be inserted into the ball joint.
SUMMARY OF THE INVENTION
There thus exists the object of creating a tripod head of the type mentioned at the beginning in which the swivelability of the ball joint relative to the bearing housing is fixable in a simple way, such that the ball joint is only still swivelable about the swiveling axis and is furthermore fixed. In addition, the ball joint fixed in its swivelability should be re-releasable in a simple manner for swiveling or rotating it about any chosen axis running through the middle point of the ball joint, whereby the danger of losing the axial element is should be avoided.
The solution of this objective with a generic tripod head consists in that the axial element is arranged outside and adjacent to the ball joint and is pivotably mounted there on the bearing housing about the swiveling axis, that the axial element has on its end facing the ball joint at least one friction element for at least friction-locking connection with the ball joint, and in that a pressing device is provided by which the friction element is pressable on the ball joint.
Advantageously, the axial element is therefore connectable with the ball joint in a friction-locking manner, so that the axial element for fixing the swivelability of the ball joint is only pressed on the outer periphery of the ball joint and only needs to be withdrawn from this to release the swivelability of the ball joint. Moreover, it is even possible to connect the axial element with the ball joint in a friction-locking manner in various pivoting and/or swiveling positions of the ball joint in the bearing house, whereby the swivelability of the ball joint can be fixed about various swiveling axes. The axial element can be connected with the bearing housing in the fixed position or in the release position, whereby a loss of the axial element is avoided.
In an especially advantageous embodiment of the invention, the friction element has a concave friction surface adapted to the curvature of the ball joint. The friction element in the operating position then engages flatly on the outer circumference of the ball joint, which makes possible the transmission of correspondingly large forces of friction, and consequently a good restriction of the swivelability of the ball joint to a pivoting motion about a swiveling axis running through the center of the ball joint.
In an advantageous embodiment, it is provided that on both sides of a central plane of the ball joint at least one ring bearing is respectively arranged in the bearing housing, which has at least one respective sliding surface acting against a restoring force on the outer circumference of the ball joint, and that the friction element of the axial element engages on an outer peripheral area of the ball joint situated between the bearings. The ring bearings can thereby be pressed with a defined pressing force against the ball joint, so that the ring bearings exert a friction moment (torque) on the ball joint when swiveling or rotating the ball joint which, with a positioning of the camera with its center of gravity laterally spaced from a vertical through the center of the ball joint, wholly or partially compensates for a rotation moment (torque) acting on the ball joint by the weight of the camera. Advantageously, the friction moment transmitted from the ring bearings to the ball joint is largely independent of the pressing force by which the friction element is pressed on the ball joint. When the friction element in release position is pressed on the ball joint, a portion of the ring bearing situated on the same side of the ball joint as the friction element is namely respectively relieved, and at the same time, a portion of the ring bearing lying opposite this portion, arranged on the side of the ball joint facing away from the friction element, is more strongly loaded.
It is especially advantageous if at least one of the ring bearings is acted upon by an adjustable pressing force, and if an adjusting mechanism is preferably provided for this, which has within its transmission path at least one spring elastic element as well as at least one impinging piece having an inclined surface movable by means of a manual activation element. The friction moment of the ball joint can then be adapted to the respective weight of the camera, whereby this friction moment is largely independent of whether the friction element is connected in a friction-locking manner with the ball joint or is loosened from this.
It is provided in a preferred embodiment of the invention that the pressing device for the axial element has an adjusting element movable approximately radially to the center of the ball joint, and that the adjusting element is braced on the axial element through a pressure bearing, in particular having a pressure ball. A simply constructed point bearing thereby results, which makes possible a largely friction-free transmission of pressing force from the adjusting element to the axial element rotatable relative thereto about the swiveling axis, when the ball joint is swivelled in the bearing housing.
An especially simply constructed pressing device, by which a comparatively large pressing forces can be applied and transmitted to the friction element, can be achieved by the adjusting element having a screw thread arranged preferably concentrically to the swiveling axis of the ball joint, which is screwable together with a matching thread of the bearing housing for a separable connection of the axial element with the ball joint.
It is advantageous if the adjusting element has an inner cavity in which the axial element is rotatably mounted about the swiveling axis of the

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