Playing surface and playing device for miniature curling

The present invention relates to a playing surface and a playing device for miniature curling.

The game of curling has its appeal largely based on the slow advancement of a throw stone along the surface of ice. As a result of this slow movement, the throw can be directed accurately and the rock's sliding distance and direction can be altered by sweeping. It is also suspenseful for a spectator of the game to watch the stone in its slow progress.

The popularity of real curling has resulted in attempts to downscale features of the game for a more convenient implementation.

There are several prior known versions of miniature games imitating the actual game of curling. The games come in a table model, as well as in floor game models.

In prior art games, an attempt has been made to minimize friction between the table and the playing device by using various antifriction lubricants, as well as by making small slide-assisting "beads" on the tabletop.

A problem with these prior known solutions is the inability to give the "throw stone" a sufficiently slow traveling speed. As a result of rescaling, the mass of a "throw stone" becomes so much smaller that the kinetic energy received thereby in a throw shall not be sufficient to carry it far enough. Consequently, it is necessary to use throwing speeds which are excessive in view of the game's scale. Hence, much of the appeal of real curling is lost.

An objective of the present invention is to provide an improved playing surface, as well as a playing device for miniature curling.

In order to accomplish this objective, a playing surface of the invention for miniature curling is characterized in that the playing surface is in the form of a sandwich structure, consisting of at least two sheets, at least one of which establishes a flexible sheet of a reversibly compressible material, on top of which is a bearing-surface establishing sheet of a pliable material, and said sheets are apt for being laid on top of a level surface of a rigid material.

A playing device of the invention is characterized in that the playing device is shaped to imitate a genuine curling stone, in that the shell portion has its bottom provided with a fabric or film type retaining means for holding the inner ball in the recess, and in that the recess has bonded to its top part a brush type or fabric or felt made soft bearing surface.

In the solution according to the invention, the trajectory and speed of a throwing device can be influenced by using the brush-resembling playing device to press a slight depression in the playing surface, whereby the easily movable throwing device slides in the direction of the depression. Thus, the traveling direction of the throwing device can be changed as appropriate. The sliding distance can be increased by pressing the tabletop with a brush in front of the playing device and, respectively, the sliding distance can be reduced by sweeping behind the playing device.

The solution according to the invention offers several benefits over the prior known solutions. It enables constructing a playing surface, which makes it possible to use brushing which is an essential aspect of the game of curling. In addition, the playing surface can be constructed economically as the surface is allowed to include planarity flaws affecting the trajectory of the throwing device. The effect of these flaws on the game can be eliminated by means of brushing. The construction of a playing device, including a heavy inner ball, and a shell portion which is light in comparison, has enabled

bringing the playing device's speed down to such an extent that playing the game genuinely resembles the actual game of curling.

The invention will be described more closely with reference to the accompa- nying drawings, in which:

fig. 1 shows one embodiment for a playing device of the invention in a cross-section,

fig. 2 shows the embodiment of fig. 1 in a plan view,

fig. 3 shows one embodiment for a playing surface of the invention in a schematic perspective view as a playing table application,

fig. 4 shows a structure for a playing surface of the invention in a schematic sectional view, and

fig. 5 is a view of principle, showing the behavior of a playing surface according to the invention with the play in progress.

Figs. 6-8 show a second embodiment for a playing device of the invention in a view from below, in a cross-section, and in a plan view, respectively.

In reference to figs. 1-2, there is shown a playing device 1, which includes a preferably an inner ball 3 of metal, around which is a cup-shaped shell portion 2 made of a light material. The shell portion and the ball have a weight ratio which is preferably within the range of about 1:100 to 10:100 and preferably within the range of about 2:100 to about 5:100. As an example, the shell portion may have a weight of about 2 g, while the ball weighs about 100 g. With a light material used for the shell layer, the latter can be shaped

as called for by the game. For example, it can be provided with a handle- resembling grip member 5 and it can have a sufficiently large outer diameter without increasing the weight too much. Thus, the playing device can be shaped to resemble a genuine throw stone in appearance. The shell portion 2 is made light by using cellular plastics, e.g. polystyrene, as its material. The shell portion can also be manufactured from injection-molded or vacuum- molded plastic components.

The shell portion 2 is provided with a downward-opening recess 4 cylindrical in cross-section for receiving the inner ball 3. The recess has preferably bonded to its top surface a brush type or fabric or felt made soft bearing surface 8, which slides on top of the ball 3, thus removing debris possibly stuck on the ball. By dimensioning the bearing surface 8 in such a way that the recess 4 has a height which is slightly less than the ball's 3 diameter, the shell portion 2 shall be supported along its upper part by the ball, such that the shell portion's bottom does not touch the playing surface or touches it just partially. With this design, the friction resulting from the shell portion can be reduced while removing ball-sticking debris from the rolling periphery. The recess 4 has a cross-sectional diameter which slightly exceeds the ball's 3 diameter. This results in a genuine-sounding collision thud, which is produced by a clearance between the ball and the shell layer and a type of material the latter is made of.

By virtue of the lightness of a material that the shell portion is made of, the friction force applied thereby on table and ball surfaces is very small and can be reduced further by using on the shell portion's bottom surface a separate antifriction material 7, e.g. a coating which contains polyester fabric, pile fabric, polytetrafluoroethylene or silicone or the like. The shell portion's bottom surface can also be given a brush type design, such as depicted in a pre- ferred embodiment of figs. 6-8 for the playing device 1, by inserting fiber bundles 41 in holes present therein, the ends of said bundles pointing per-

b pendicularly to the sliding surface. With this design, the debris present on the playing surface does not interfere with the sliding movement, because the brush type sliding surface flexes and removes the debris out of its way or carries it along without disturbing the sliding movement.

In addition to establishing a sliding surface, the fabric or the like, bonded to the bottom part e.g. by gluing, may serve as a retaining means for the ball 3, having an opening in line with the recess 4 for accommodating the ball 3 in the recess and for removing it e.g. for cleaning purposes. The retaining means normally holds the ball inside the recess, but in the process of installing the ball in and removing it from the recess, the retaining means recedes, thus extending the opening and allowing the ball to pass through the opening. Instead of using a fabric or e.g. a plastic film, the retaining means can also be implemented by providing the recess with a retaining boss or by nar- rowing the recess opening to make it smaller than the ball's diameter, in which case the ball is insertable into the recess by forcing it over the retaining boss or through the narrowed mouth opening with the shell portion material yielding away to a required extent.

The retaining means may also comprise a rod-like element 40, as shown in an embodiment of figs. 6-8 for the playing device 1, which is insertable through the shell portion 2 to extend across the recess 4 at a location below what is a horizontal middle plane of the inner ball 3, thus preventing the ball from falling out of the recess.

The retaining means is not absolutely necessary, since the playing device is normally held at all times on top of the playing surface, the "throwing action" being performed by pushing the playing device with a follow-through or by nudging it to make the playing device move forward in response to a rotating motion of the ball. At the same time, the ball-covering shell portion creates an impression of the playing device's sliding motion, resembling the motion

of a throw stone in the genuine game of curling. Naturally, when using a retaining means, it is possible to perform the throwing action by holding the playing device off the surface in the beginning of a throwing action, whereby the throwing action resembles more closely that of the real game of curling.

Rg. 3 shows schematically one embodiment for a playing table 10 making use of a playing surface 12 of the invention. The playing table has legs 11 supporting the playing surface 12, having its playing sheet provided with curling markings 14 at both ends. The playing sheet is surrounded by a boarding 13. As shown in fig. 4, the playing surface includes a rigid level surface 20, on top of which is laid a flexible sheet 21 of a reversibly compressible material, and on top of that lies a bearing-surface establishing sheet 22 of a pliant material. The level surface 20 can be made e.g. of glass. The flexible sheet 21 is preferably made of a closed- or open-cell polymer mate- rial, such as e.g. polyethylene cellular plastics or polyether. It may also be a flexible sheet made of fibers or crushed elastomer. The flexible sheet 21 has a thickness which is preferably within the range of about 0.8 to 2 mm.

The sheet of a pliant material consists preferably of a panel type polymer material capable of retaining its flatness, such as e.g. a polycarbonate panel whose thickness is preferably within the range of about 1.5 to 2.5 mm. The sheet of a pliant material is also preferably the one to establish the actual playing sheet. However, the pliant sheet can be topped with a leveling layer made of a soft elastic material, and on top of that can be a thin surface film with a thickness in the order of 0.5 mm. The leveling layer may consist of an elastic soft solid substance or it may also be cell-structured or it may be an even-thickness liner or fabric made of fibers. The leveling layer's thickness may fluctuate between 0.2 and 4 mm, depending on the hardness and structure of the material. The leveling layer is preferably a mat type material, but it can also be a cast material, which, upon setting, provides said soft elastic

leveling layer. The leveling layer may also consist of an adhesive type material, bonding the surface film and the pliant sheet to each other.

The playing surface may also consist of several overlying flexible and pliant sheets, such that a suitable depression is provided by pressing with a brush. What is nevertheless essential about the solution according to the invention is that at least one of the flexible sheets is made of a material whose volume becomes smaller in compression and, after the compression is over, its volume returns to original.

In view of the actual implementation of court markings, it is advisable that the sheets of the playing surface be constructed from an at least partially transparent material, in which case the markings can be made underneath the actual playing sheet.

The playing table 10 has its measurements resembling the dimensions of a real curling sheet, the ratio of length to width being preferably within the range of about 1:3 to about 1:10.

The playing device 1 according to the invention, which consists of a heavy inner ball and a light shell portion, and the playing surface according to the invention make up a combination which enables the creation of an exceptionally good impression of a genuine game of curling. The playing surface according to the invention can be used in a table model miniature curling game or it can be installed on a flat foundation, for example on the floor or on a sturdy table. In a floor game, the brush shafts can be long just like in real curling and the brush can also be used for "throwing" the playing device with a push motion.

It is in the nature of the game of curling that the movement of a playing device can only be influenced a little by sweeping. When using a playing sur-

face of the invention, the effect of sweeping on the movement of a playing device can be adjusted appropriately by selecting a force needed for the compression of a material of the flexible sheet 21 and a compression distance of the same, as well as the thickness and bending stiffness of the pli- ant sheet 22, such that the size of a depression will be desirable from game playing standpoint. A typical feature of cellular plastics is that, in the process of compression, it flexes consistently at first until the walls of the cells come to contact with each other, at which point the flexing stops abruptly. This feature can be utilized in the process of making a playing surface, wherein the depression produced in the top sheet by the force of sweeping does not become excessive. A functional brush control is obtained when the depression is gentle and a distance L2 of its edge from the brush is sufficiently long to enable performing the sweeping action at a suitable distance away from the sliding playing device 1. This is detailed schematically in fig. 5. Another essential aspect from the functional point of view is that the distance L2 in fig. 5 exceeds Ll. Hence, the depression's edge extends all the way to a center axis a of the playing device, bringing its rolling ball onto an inclined surface, thus making it roll towards the center of the depression. Since the inclination at the edge of the depression should be such that the playing device 1 does not set off by the action of sweeping alone, the bending stiffness and flexion extent of the sandwich structure are preferably dimensioned in such a way that, when pressing with a reasonable sweeping force alongside the throwing device at a short distance L3 therefrom, the result is an extensive depression exceeding the distance Ll and, at the location of the playing de- vice's center axis a, the depression has its surface inclined by an angle k relative to a horizontal plane V. When the angle of inclination k has a tangent which is lesser than the static friction coefficient between a playing device and a playing sheet, the result is a miniature curling game in which the playing device cannot be moved by sweeping alone. The sweeping feature of the game provides also a significant extra benefit as it enables keeping the playing sheet clean and at same time polishing the sliding surface, wherein the

debris fallen onto the surface and possible scratches therein do not hamper the sliding motion of a playing device.

It is also conceivable to make the playing surface slightly chute-shaped in a longitudinal direction, e.g. by placing inlay strips between the surface sheets for raising the edge region to a higher level. The strips could be e.g. advertising material. Alternatively, the level surface can be prefabricated in a chute-like shape.