Patent Description:
Several moveable mounts exist for telescopes or other optical instruments. Two main types of telescope mounts are equatorial mounts and altitude-azimuthal mounts. Each of these mounts is configured so that a telescope (supported by the mount) can be moved on two orthogonal axes.

<CIT> discloses an equatorial mount for an optical instrument. <CIT> discloses a worm gear. <CIT> discloses a worm wheel of an electric power steering apparatus.

Equatorial mounts compensate for Earth's rotation and provide single-axis tracking of celestial objects. For example, the German equatorial mount typically has a right ascension shaft, a declination shaft, and a counterweight shaft. The right ascension shaft is rotatable relative to the base about a right ascension axis. The declination shaft is rotatable relative to the right ascension shaft about a declination axis. The declination axis is orthogonal to the right ascension axis. The counterweight shaft is mounted to one end of the right ascension shaft and extends from the right ascension shaft along a counterweight axis that is co-linear with the declination axis.

Altitude-azimuthal mounts, also referred to as altazimuth mounts or alt-az mounts, rotate an optical instrument about two perpendicular axes: an azimuthal axis and an altitude axis. The orientation of an optical instrument mounted on an alt-az mount corresponds to a set of coordinates referred to as the alt-az coordinates. The alt-az coordinates are typically expressed in degrees of altitude and azimuth. Altitude represents the angular orientation of an optical instrument about the altitude axis relative to the horizon. Altitude is typically expressed in a range of -<NUM>° to <NUM>°, with <NUM>° representing the horizon. The point at <NUM>° is a point that is directly overhead for an observer. The point directly overhead is called the zenith. Azimuth represents the angular orientation of an optical instrument about the azimuthal axis and is expressed in a range of <NUM>° to <NUM>°. Typically, azimuth is selected to represent the true compass (as opposed to magnetic) heading towards a point on the horizon and is measured eastwardly from the North celestial pole.

Worm gear assemblies are often used in both equatorial mounts and altitude-azimuthal mounts to enable rotation of a mounted telescope. A worm gear assembly includes a worm shaft (also referred to as a worm and a worm screw) and a worm wheel (also referred to as a worm gear). The worm shaft and the worm wheel cooperate with one another, so that rotation of the worm shaft about a worm axis causes corresponding rotation of the worm wheel about a wheel axis that is generally orthogonal to the worm axis. In a motorized mount, a motor typically acts on a worm shaft, which in turn cooperates with a worm wheel. In practice, the mechanical engagement between the worm wheel and the worm shaft is often too loose or too tight. When the engagement is too loose, the orientation of a mounted optical instrument may not be adjusted with a high precision. When the engagement is too tight, it may be difficult to turn the worm shaft and this may result in increased friction and associated wear and tear of the worm gear assembly.

There is a general desire for a worm gear assembly for a mount for a telescope or other optical instrument that allows ease of operation, prevents pre-mature wear and tear, and/or enables precise adjustment of a mounted optical instrument.

The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.

The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements.

One aspect of the invention provides a mount for a telescope or other optical instrument according to claim <NUM>.

In an example useful for understanding the invention, but not covered by the subject-matter of the claims, a worm gear assembly for use with a mount for a telescope or other optical instrument is provided comprising a holder for supporting an optical instrument mounted thereto, where operation of the worm gear assembly enables the holder to move relative to a base about a wheel axis. The worm gear assembly comprises: a worm wheel rigidly connected to the holder, such that movement of the worm wheel about the wheel axis causes corresponding movement of the holder about the wheel axis; and a worm shaft comprising a worm body extending in a longitudinal direction and a thread extending in a spiral on the worm body around a longitudinally oriented worm axis that is orthogonal to the wheel axis, the worm shaft supported by the base for rotational movement about the worm axis. The worm wheel comprises a generally disc-shaped wheel body comprising a plurality of radially extending and circumferentially spaced apart teeth at a radially outermost peripheral surface for engaging the thread of the worm shaft, so that rotation of the worm shaft about the worm axis causes, by engagement of the teeth with the thread, corresponding rotation of the worm wheel about the wheel axis and corresponding relative rotation of the holder and the base about the wheel axis. The wheel body is shaped to define a plurality of elasticity-enhancing cutouts spaced apart from the wheel axis and extending through the wheel body in a directions parallel to the wheel axis.

Each one of the elasticity-enhancing cutouts may be defined, at least in part, by a pair of continuous cut-out defining surfaces. The continuous cut-out defining surfaces may meet at a first discontinuous corner. The continuous cut-out defining surfaces may meet at the first discontinuous corner and at a second discontinuous corner. The first and second corners may be spaced apart from one another (e.g. in an angular direction around the wheel axis).

The continuous cut-out defining surfaces may be continuously curved. The continuous cut-out defining surfaces may be arcuate. The continuous cut-out defining surfaces may comprise different radii of curvature. The continuous cut-out defining surfaces may comprise different centers of curvature.

The elasticity-enhancing cutouts may each comprise a generally crescent-shaped cross section in a cross-sectional direction orthogonal to the wheel axis.

Each one of the elasticity-enhancing cutouts may be defined by a cut-out defining surface. The cut-out defining surface may comprise a first arcuate portion and a second arcuate portion connected to the first arcuate portion by a pair of spaced apart discontinuities. The first arcuate portion and the second arcuate portion may comprise different centers of curvature. The first arcuate portion and the second arcuate portion may comprise different radii of curvature.

Each one of the elasticity-enhancing cutouts may be defined, at least in part, by a plurality of continuous cut-out defining surfaces. At least one pair of the plurality of continuous cut-out defining surfaces may meet at a discontinuous corner. The continuous cut-out defining surfaces may be arcuate.

The elasticity-enhancing cutouts may each comprise a generally triangular cross section in a cross-sectional direction orthogonal to the wheel axis.

Each one of the elasticity-enhancing cutouts may be defined, at least in part, by four continuous cut-out defining surfaces. Two of the four continuous cut-out defining surfaces may extend radially from the wheel axis and the other two of the four continuous cut-out defining surfaces may extend circumferentially about the wheel axis.

The continuous cut-out defining surfaces may each extend in a direction that is parallel to the wheel axis.

The elasticity-enhancing cutouts may be shaped or located such that any notional radial line between the wheel axis and the teeth intersects at least one pair of continuous cut-out defining surfaces has one or more discontinuities therebetween. At least one notional radial line may intersect a second pair of continuous cut-out defining surfaces having one or more discontinuities therebetween.

The elasticity-enhancing cutouts may be positioned at uniform angular intervals about the wheel axis.

A ratio of the volume of the elasticity-enhancing cutouts to the volume of the worm wheel may be between about <NUM>% and about <NUM>%, thereby providing a wheel body having a mass that is about <NUM>% to about <NUM>% lower than a mass that the wheel body would have if made from solid material.

The base may be moveable relative to a base support component and the worm shaft may be supported by the base such that movement of the base relative to the base support component causes corresponding movement of the worm axis and the wheel axis, while maintaining the orthogonality therebetween.

In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions.

Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.

In an example useful for understanding the invention, but not covered by the subject-matter of the claims, an elastic worm gear assembly is described herein. The elastic worm gear assembly may be used in a moveable mount for a telescope or other optical instrument. The elastic worm gear assembly comprises a worm shaft and a worm wheel that is mounted for operational engagement with the worm shaft such that rotation of the worm shaft about a worm axis causes corresponding rotation of the worm wheel about a wheel axis that is orthogonal to the worm axis. The worm shaft comprises a worm body extending in a longitudinal direction (generally parallel to the worm axis) and a thread extending in a spiral on an external surface of the worm body around the worm axis. The worm wheel comprises a generally disc-shaped wheel body comprising a plurality of radially extending and circumferentially spaced apart teeth at a radially outermost peripheral surface for engaging the thread of the worm shaft. The wheel body is shaped to define a plurality of elasticity-enhancing cutouts spaced apart from the wheel axis and extending through the wheel body in a direction parallel to the wheel axis. The elasticity-enhancing cutouts confer enhanced elasticity to the wheel body (relative to a solid wheel body), so that the worm wheel is more resiliently (elastically) deformable (relative to a solid wheel body) in a radial direction toward the wheel axis. In some embodiments, the elasticity-enhancing cutouts confer enhanced elasticity to the wheel body so that the worm wheel is more resiliently (elastically) deformable (relative to a solid wheel body) in other direction(s), such as in a direction parallel to the wheel axis and/or a circumferential direction. In some embodiments, a ratio of the volume of the elasticity-enhancing cutouts to the volume of the worm wheel is between about <NUM>% and about <NUM>%, thereby providing a wheel body having a mass that is about <NUM>% to about <NUM>% lower than a mass that the wheel body would have if made from solid material. When the elastic worm gear assembly is incorporated in a telescope mount, the elasticity-enhancing cutouts help to achieve an engagement between the elastic worm wheel and the worm shaft that is relatively close to an ideal engagement (e.g. neither too tight nor too loose) when compared to a conventional worm gear assembly, to thereby enable precise adjustment of a telescope mounted on the telescope mount.

As used herein, unless the context dictates otherwise, the terms "elastic" and "resiliently deformable" mean that a worm wheel is able to return to its original shape after the worm wheel is deformed by an applied force and the applied force is subsequently removed.

As used herein, unless the context dictates otherwise, the terms "about" and "approximately" mean plus and minus <NUM>%.

As used herein, unless the context dictates otherwise, the term "generally" means in general terms. For example, a "generally disc-shaped wheel body" means that the wheel body has an overall shape of a disc, but it does not need to be a perfectly circular in cross-sectional shape.

As used herein, unless the context dictates otherwise, the term "continuity" or "continuous" or "continuously" means a smooth transition. In contrast, the term "discontinuity" or "discontinuous" or "discontinuously" means a non-smooth transition. For example, an elasticity-enhancing cutout may be defined by a pair of continuous cutout defining surfaces wherein the continuous cutout defining surfaces are connected (or meet) at discontinuous (i.e. non-smooth, characterized by a sharp angle) corners, where the radii of curvature of such discontinuous corners is less than <NUM> or, in some embodiments, less than <NUM> or, in some embodiments, less than <NUM> or, in some embodiments, less than <NUM>.

The following description sets forth specific details in order to provide a more thorough understanding to persons skilled in the art. It describes:.

However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

<FIG> shows a perspective view of a worm gear assembly <NUM> comprising a worm shaft <NUM> and an elastic worm wheel <NUM>. Worm shaft <NUM> and elastic worm wheel <NUM> are operably engaged.

Focusing on the structural features of worm shaft <NUM>, worm shaft <NUM> comprises a worm body <NUM> extending in a longitudinal direction <NUM>. At least a portion of worm body <NUM> is circumscribed by a single thread <NUM>. Single thread <NUM> extends in a spiral about a longitudinally-oriented worm axis <NUM> on an outer surface of worm shaft <NUM>. Worm axis <NUM> extends in longitudinal direction <NUM> and is aligned with a central axis of worm body <NUM>. In the illustrated embodiment, single thread <NUM> is a V-type thread with a V-shaped cross section. In other embodiments, worm body <NUM> may be wrapped by multiple threads. Worm body <NUM> may be wrapped by a non-V-type thread. The entire worm body <NUM> may be wrapped by a thread. Worm shaft <NUM> may be a single enveloped worm or a double enveloped worm. Worm shaft <NUM> may have threads that form a single start or multiple starts. Worm shaft <NUM> may be integrally formed and can be made of any suitable materials. For example, worm shaft <NUM> may be entirely made of metal or plastic. Worm body <NUM> and thread <NUM> may be made of different materials, for example with worm body <NUM> made of metal and thread <NUM> made of plastic. Overall, worm shaft <NUM> can be any threaded worm known in the art as long as worm shaft <NUM> can operably engage worm wheel <NUM>, so that torque can be transmitted from worm shaft <NUM> to worm wheel <NUM>.

With respect to worm wheel <NUM>, worm wheel <NUM> comprises a generally disc-shaped wheel body <NUM>. Disc-shaped wheel body <NUM> of the illustrated embodiment has a central fitting hole portion <NUM> although in other embodiments, central fitting hole portion <NUM> may be omitted. Disc-shaped wheel body <NUM> comprises a plurality of radially extending and circumferentially spaced-apart teeth <NUM> at a radially outermost peripheral surface <NUM>. Space <NUM> between adjacent teeth <NUM> is shaped for engaging thread <NUM> of worm shaft <NUM>, so that rotation of worm shaft <NUM> about worm axis <NUM> causes corresponding rotation of worm wheel <NUM> about a wheel axis <NUM>. Wheel axis <NUM> is orthogonal to worm axis <NUM>.

Wheel body <NUM> is shaped to define a plurality of elasticity-enhancing cutouts <NUM> which confer a degree of elasticity to wheel body <NUM>, so that worm wheel <NUM> is more resiliently (elastically) deformable (relative to a solid wheel body) in a radial direction towards wheel axis <NUM>. In some embodiments, the elasticity-enhancing cutouts confer enhanced elasticity to wheel body <NUM> so that worm wheel <NUM> is more resiliently (elastically) deformable (relative to a solid wheel body) in other direction(s), such as in directions parallel to the wheel axis and/or circumferential directions. Elasticity-enhancing cutouts <NUM> are spaced apart from wheel axis <NUM>. Elasticity-enhancing cutouts <NUM> extend through wheel body <NUM> in a direction parallel to wheel axis <NUM>.

To provide a desired level of elasticity while maintaining a desired level of physical rigidity, in some embodiments, the ratio of the volume of elasticity-enhancing cutouts <NUM> to the volume of worm wheel <NUM> is between about <NUM>% and about <NUM>%, thereby providing a wheel body having a mass that is about <NUM>% to about <NUM>% lower than a mass that the wheel body would have if made from solid material. The ratio may be any value between about <NUM>% and about <NUM>%, e.g. <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, and <NUM>%. The ratio of the volume of elasticity-enhancing cutouts <NUM> to the volume of worm wheel <NUM> may change depending on the shape and placement of elasticity-enhancing cutouts <NUM>.

Elasticity-enhancing cutouts <NUM> can have any suitable shapes and dimensions. Also, elasticity-enhancing cutouts <NUM> can be arranged in any suitable placement. The shapes, dimensions, and/or placement of elasticity-enhancing cutouts <NUM> confer a level of elasticity to wheel body <NUM>, so that worm wheel <NUM> is resiliently deformable in a radial direction towards wheel axis <NUM>.

Focusing on the currently desired shapes of elasticity-enhancing cutouts <NUM>, elasticity-enhancing cutouts <NUM> may be an oblong shape, a boomerang shape, a rectangular shape, or a triangular shape. Elasticity-enhancing cutouts <NUM> may be identical to or different from each other.

In the illustrated embodiment, elasticity-enhancing cutouts <NUM> have the same shape and dimensions. For brevity, only one elasticity-enhancing cutout <NUM> is described in detail below. Elastic-enhancing cutout <NUM> is curved and forms a generally crescent shape in a cross-sectional direction orthogonal to wheel axis <NUM>. Elasticity-enhancing cutout <NUM> extends from an inner radius <NUM> to an outer radius <NUM> in an arcuate direction <NUM>. Elasticity-enhancing cutout <NUM> is defined by a pair of continuous cut-out defining surfaces <NUM>, <NUM>. Continuous cut-out defining surfaces <NUM>, <NUM> each extend through wheel body <NUM> in a direction parallel to wheel axis <NUM>, although in some other embodiments, not covered by the subject-matter of the claims, continuous cut-out defining surfaces <NUM>, <NUM> may extend through wheel body <NUM> in a direction that intersects wheel axis <NUM>. Continuous cut-out defining surfaces <NUM>, <NUM> are each arcuate, smooth and free from sharp edges. Continuous cut-out defining surfaces <NUM>, <NUM> of the illustrated embodiment have different centers of curvature and different radii of curvature, although this is not necessary. Continuous cut-out defining surfaces <NUM>, <NUM> are connected and meet at discontinuous corners <NUM>, <NUM>. The radii of curvature at discontinuous corners <NUM>, <NUM> may be less than <NUM> or, in some embodiments, less than <NUM> or, in some embodiments, less than <NUM> or, in some embodiments, less than <NUM>.

In terms of the placement of elasticity-enhancing cutouts <NUM>, the placement may be impacted by the shapes and dimensions of elasticity-enhancing cutouts <NUM>. This is because the shapes, dimensions, and placement of elasticity-enhancing cutouts <NUM> function together to confer a desired level of elasticity to wheel body <NUM> and worm wheel <NUM>.

In the illustrated embodiment, elasticity-enhancing cutouts <NUM> are located (and shaped) such that any notional radial line between wheel axis <NUM> and teeth <NUM> intersect at least one pair of continuous cut-out defining surfaces <NUM>, <NUM> having one or more discontinuities <NUM>, <NUM> therebetween. Further, elasticity-enhancing cutouts <NUM> are located (and shaped) such that at least one notional radial line intersects a second pair of continuous cut-out defining surfaces <NUM>', <NUM>' having one or more discontinuities therebetween <NUM>', <NUM>'. In other words, elasticity-enhancing cutouts <NUM> are positioned in a staggered manner, so that one or more pairs of adjacent elasticity-enhancing cutouts <NUM> overlap in some degree in a circumferential direction and are separated in a radial direction.

In the illustrated embodiment, elasticity-enhancing cutouts <NUM> are spaced apart at a uniform angular interval about wheel axis <NUM>.

Some other embodiments of elasticity-enhancing cutouts <NUM> are schematically shown in <FIG> shows a worm wheel 14A having a plurality of elasticity-enhancing cutouts 36A. Each one of elasticity-enhancing cutouts 36A is defined by four continuous cut-out defining surfaces <NUM>, <NUM>, <NUM>, <NUM>. Elasticity-enhancing cutouts 36A comprises a rectangular cross section taken in a cross-sectional direction orthogonal to wheel axis 18A. In other words, each one of elasticity-enhancing cutouts 36A is defined by four continuous surfaces <NUM>, <NUM>, <NUM>, <NUM>. <FIG> shows a worm wheel 14B having a plurality of elasticity-enhancing cutouts 36B. Each one of elasticity-enhancing cutouts 36B is defined by a continuous cut-out defining surface 56B. Continuous cut-out defining surface 56B comprises a first curved portion 58B and a second curved portion 60B connected to first curved portion 58B. First curved portion 58B and second curved portion 60B have the same center of curvature although they have different radii of curvature. Elasticity-enhancing cutouts 36B each comprise a generally boomerang-shaped cross section in a cross-sectional direction orthogonal to the wheel axis 18B. <FIG> shows a worm wheel 14C having a plurality of elasticity-enhancing cutouts 36C. Each one of elasticity-enhancing cutouts 36C comprises an oblong section taken in a cross-sectional direction orthogonal to wheel axis 18C. In other words, elasticity-enhancing cutouts 36C each is defined by a continuous cut-out defining surface. A person skilled in the art would appreciate that elasticity-enhancing cutouts may have any suitable shapes and dimensions that provide worm wheel <NUM> with the desired elasticity properties. Other possible embodiments include elasticity-enhancing cutouts defined by three continuous cut-out defining surfaces. The three continuous cut-out defining surfaces may be curved and may meet at three discontinuous corners. The elasticity-enhancing cutouts each may comprise a generally triangular cross section in a cross-sectional direction orthogonal to the wheel axis.

Worm wheel <NUM> may be integrally formed and can be made of any suitable materials. In some embodiments, worm wheel <NUM> is entirely made of metal or plastic. In some other embodiments, worm wheel body <NUM> and teeth <NUM> are made of different materials. For example, worm wheel body <NUM> may be made of metal and teeth <NUM> may be made of plastic.

In operation, worm shaft <NUM> and elastic worm wheel <NUM> are mounted in operational engagement with one another, so that when worm shaft <NUM> rotates about worm axis <NUM>, worm shaft <NUM> acts on and rotates worm wheel <NUM> about wheel axis <NUM>. Worm rotation axis <NUM> and wheel rotation axis <NUM> are oriented perpendicular to each other and do not intersect. Thread <NUM> engages with teeth <NUM>, so that the turning actions of worm shaft <NUM> act on and drive worm wheel <NUM>. Worm wheel <NUM> is resiliently (elastically) deformable in a radial direction towards wheel axis <NUM> (e.g. more elastically deformable than a solid worm wheel). In some embodiments, the elasticity-enhancing cutouts <NUM> confer enhanced elasticity to wheel body <NUM>, so that worm wheel <NUM> is more resiliently (elastically) deformable (relative to a solid wheel body) in other direction(s) such as in directions parallel to the wheel axis and/or circumferential directions. When thread <NUM> is received space <NUM> between adjacent teeth <NUM>, worm shaft <NUM> may press on worm wheel <NUM>, so that worm wheel <NUM> is elastically compressed inwardly towards wheel axis <NUM>. The compression force acts on outer peripheral surface <NUM>, thereby causing worm wheel <NUM> to deform radially and inwardly. The resilient deformation of worm wheel <NUM> promotes engagement and minimizes backlash between worm <NUM> and worm wheel <NUM> with worm <NUM> rotating about worm rotation axis <NUM>.

As an example useful for understanding the mount according to the invention, but not covered by the subject-matter of the claims, worm gear assembly <NUM> can be incorporated in mount for a telescope or other optical instrument. When incorporated in a mount, worm gear assembly <NUM> enables precise adjustment of a telescope mounted on the mount. This is because elasticity-enhancing cutouts <NUM> and the corresponding resilient deformation of worm wheel <NUM> encourage an ideal engagement between elastic worm wheel <NUM> and worm shaft <NUM> that is neither too tight nor too loose (e.g. mitigating backlash).

An example embodiment of a mount <NUM> that incorporates worm gear assembly <NUM> is shown in <FIG>. Mount <NUM> is a handheld alt-az mount, where precise adjustment of the altitude-azimuthal coordinates can be a challenge. The deployment of worm gear assembly <NUM> in handheld alt-az mount <NUM> facilitates relatively accurate altitude and/or azimuth adjustment (relative to a mount incorporating a solid worm gear assembly), because of the resilient deformability of worm wheel <NUM>.

Handheld alt-az mount <NUM> comprises a holder <NUM> for supporting an optical instrument (not shown) mounted thereto. Holder <NUM> is rotationally moveable relative to a base <NUM> about an altitude axis <NUM> and an azimuth axis <NUM> by operation of an altitude-rotation mechanism <NUM> and an azimuth-rotation mechanism <NUM>, respectively. The structural features of altitude-rotation mechanism <NUM> and azimuth- rotation mechanism <NUM> may be substantially the same in terms of their worm gear assemblies <NUM>. For brevity, only altitude-rotation mechanism <NUM> is described in detail below.

As shown in <FIG>, altitude-rotation mechanism <NUM> comprises worm gear assembly <NUM> that includes worm shaft <NUM> rotatable about worm axis <NUM> and worm wheel <NUM> rotatable about wheel axis <NUM>. Worm shaft <NUM> is supported for rotatable motion about worm axis <NUM> (<FIG>) in a sleeve <NUM> (<FIG>). Sleeve <NUM> may form part of holder support component <NUM> or may be rigidly mounted to holder support component <NUM>. Holder support component <NUM> supports holder <NUM> and rotates with holder <NUM> about azimuth axis <NUM> by the action of azimuth-rotation mechanism <NUM>. However, holder <NUM> rotates relative to holder support component <NUM> about altitude axis <NUM> by the action of altitude-rotation mechanism <NUM>, as explained in more detail below.

As shown best in <FIG>, worm shaft <NUM> of altitude-rotation mechanism <NUM> is rotatable about its worm axis <NUM> within sleeve <NUM>. Sleeve <NUM> is located such that rotation of worm shaft <NUM> causes corresponding rotation of worm wheel <NUM> about wheel axis <NUM> which may be collinear with altitude axis <NUM>. Worm wheel <NUM> is rotatably supported on rod bearing <NUM> of holder support component <NUM>, such that worm wheel <NUM> is rotatable about altitude axis <NUM> (wheel axis <NUM>) by bearing on the surface of rod bearing <NUM>. In the illustrated embodiment, worm wheel <NUM> comprises a keyed collar <NUM> having a pair of key slots 115A. Holder <NUM> fits over keyed collar <NUM>, so that corresponding key protrusions (not shown) of holder <NUM> fit into key slots 115A. In this manner, rotation of worm shaft <NUM> about worm axis <NUM> (e.g. by a user in some embodiments or by a suitably configured motor in some embodiments) causes corresponding rotation of worm wheel <NUM> about altitude axis <NUM> (wheel axis <NUM>) and when worm wheel <NUM> rotates, keyed collar <NUM> rotates which in turn causes holder <NUM> to rotate about altitude axis <NUM> by the engagement of the key protrusions of holder <NUM> into key slots 115A. As discussed above, worm wheel <NUM> comprises cutouts <NUM> (not specifically enumerated in <FIG>) which provide a relatively high degree of elastic deformability to worm wheel <NUM> (relative to a solid worm wheel) and the corresponding benefits to altitude-rotation mechanism <NUM> (as discussed elsewhere herein).

Persons skilled in the art will appreciate that in examples not covered by the subject-matter of the claims altitude-rotation mechanism <NUM> may be constructed with other specific configurations which use worm wheel assembly <NUM> to facilitate rotational movement of one component (e.g. holder <NUM>) relative to another component (e.g. holder support component <NUM>) about an altitude axis <NUM> and which take advantage of worm wheel assembly <NUM> and deformable worm wheel <NUM>. Persons skilled in the art will appreciate that in examples not covered by the subject-matter of the claims an azimuth-rotation mechanism <NUM> may be similarly constructed with similar configurations which use worm wheel assembly <NUM> to facilitate rotational movement of one component (e.g. holder support component <NUM>) relative to another component (e.g. base <NUM>) about an azimuth axis <NUM> and which take advantage of worm wheel assembly <NUM> and deformable worm wheel <NUM>.

In some embodiments, mount <NUM> may be an equatorial mount comprising a holder for supporting an optical instrument mounted thereto, the holder rotationally movable relative to a base about right ascension and declination axes, by corresponding right ascension and declination rotation mechanisms where one or both of the right ascension and declination rotation mechanisms comprises a worm gear assembly <NUM> having a deformable worm wheel <NUM>.

Claim 1:
A mount for a telescope or other optical instrument comprising:
a base (<NUM>);
a holder (<NUM>) for supporting an optical instrument mounted thereto;
a worm gear assembly (<NUM>);
the holder (<NUM>) movable relative to the base (<NUM>) about a wheel axis (<NUM>, <NUM>) by operation of the worm gear assembly (<NUM>);
the worm gear assembly (<NUM>) comprising:
a worm wheel (<NUM>) rigidly connected to the holder (<NUM>), such that movement of the worm wheel (<NUM>) about the wheel axis (<NUM>) causes corresponding movement of the holder (<NUM>) about the wheel axis (<NUM>);
a worm shaft (<NUM>) comprising a worm body (<NUM>) extending in a longitudinal direction (<NUM>) and a thread (<NUM>) extending in a spiral on the worm body (<NUM>) around a worm axis (<NUM>) that extends in the longitudinal direction (<NUM>) and is orthogonal to the wheel axis (<NUM>), the worm shaft (<NUM>) supported by the base (<NUM>) for rotational movement about the worm axis (<NUM>) ;
the worm wheel (<NUM>) comprising a generally disc-shaped wheel body (<NUM>) comprising a plurality of radially extending and circumferentially spaced apart teeth (<NUM>) at a radially outermost peripheral surface for engaging the thread (<NUM>) of the worm shaft (<NUM>), so that rotation of the worm shaft (<NUM>) about the worm axis (<NUM>) causes, by engagement of the teeth (<NUM>) and the thread (<NUM>), corresponding rotation of the worm wheel (<NUM>) about the wheel axis (<NUM>) and corresponding relative rotation of the holder (<NUM>) and the base (<NUM>) about the wheel axis (<NUM>); characterized in that
the wheel body (<NUM>) is shaped to define a plurality of elasticity-enhancing cutouts (<NUM>) spaced apart from the wheel axis (<NUM>) and extending through the wheel body (<NUM>) in directions parallel to the wheel axis (<NUM>), the elasticity-enhancing cutouts (<NUM>) enhancing elasticity of the worm wheel (<NUM>) in a radial direction relative to a solid wheel body such that the worm wheel (<NUM>) can deform radially and inwardly.