JPH02501043A - Conductive tennis ball and line determination device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] name of invention Field of the invention: conductive tennis ball and line determining device The present invention applies to tennis balls that strike the ground within or outside the playing area of a tennis court. automatic tennis court line to detect whether you hit the top of the net or not This invention relates to improvements in electrically conductive tennis balls used in calling systems. this Type line calling system in selected areas of the tennis court.

and detect the drop of an electrically conductive ball extending along the top of the net. It includes one or more pairs of exposed, spaced apart conductors.

When the ball crosses two or more sensing conductors and hits the ground, the ball A current conduction circuit is completed through the player, and the ball is present in the conductor. Inform the area that you have arrived in the evening.

The electrical conductivity of tennis balls is achieved by incorporating electrically conductive fibers inside the outer skin of the ball. This can be achieved by

Summary and purpose of the invention According to the invention, a mixture of electrically conductive and non-conductive fibers is spun together. It is threaded to form threads for weaving the fabric of the tennis ball's outer skin. These conductivity and and non-conducting fibers.

It is not stable, but a filament of random length.

The electrically conductive fibers can be made of stainless steel. take another form and is incorporated herein by reference.

John A. on November 10, 1981 U.S. Patent No. 4,299,384 issued to Van Aukcn Another type of electrically conductive film, such as that described in the specification for "Conductive Game Balls" It is also possible to use a fiber.

, in one embodiment of the invention, the electrically conductive fibers are not warp yarns of the woven fabric; Incorporation into the weft or filling is desirable. In another embodiment, the electrical Conductive fibers are incorporated into both the weft and the filling. In both these examples Leave it behind.

It is desirable that the weft threads be much thicker and coarser than the warp threads; The area occupied by the weft threads on the outer surface of the ball's shell is much larger than the area occupied by the warp threads. It is desirable to weave it against the warp so that it is wide.

In some illustrated embodiments, the tennis ball is elastically connected to the woven outer skin of the ball. with an electrically conductive base located between the deformable core and conductive fibers within the outer skin. It is desirable to be able to improve the conductivity between the bars. This electrically conductive base is extending around the entire circumference of the core, bridging the seams between the skin panels and providing conductive material between the panels. It is desirable to be able to achieve commonality.

The electrically conductive base serves the additional function of adhering the outer skin to the core of the ball. It can be used as an electrically conductive adhesive.

For example, the electrically conductive base may be of the type described in U.S. Pat. No. 4,299,384. A scrim of electrically conductive fibers may be used. In another form, electrotransmission The conductive base is a thin-walled and flexible material that can be glued to the back side of the outer skin. It can be in the form of a woven or non-woven fabric or a mat. Electrically conductive adhesive It can also be used with a conductive scrim or mat to connect the outer skin in place over the core of the ball. You can also wear it.

In addition, we applied an electrically conductive coating to the fabric used for the outer skin of tennis balls. It is also possible to improve the conductivity of the electrical conduction path. This coating is applied to the ball In its final form.

Apply only to the back side of the fabric, which is the inside of the outer skin. This coating can be applied to tennis fabrics. It can be applied before or after cutting out the ball skin panels.

The woven fabric of the tennis ball outer skin is sewn with a needle, preferably by breaking the fibers. This changes the direction of the numerous electrically conductive and non-conductive fibers of the woven thread, without changing the direction of the woven thread. to cause the redirected fibers to extend more transversely to the plane of the fabric. is desirable. Because of this needle-sewing process, other sections of numerous electrically conductive fibers are The free end extends beyond the plane of the fabric at least on the back side of the fabric and provides electrical conductivity as described above. a conductive base (if employed) or an electrically conductive coating (if employed) as described above. ) or otherwise engaged with a ball along the underside of the skin. This will improve the conductivity of the electrical conduction path of the cable.

The weave pattern of the weft and warp yarns, as well as other features of the invention, make it possible to A ball that is sufficiently conductive to activate the ball detection circuit on a varnish coat. The number of electrically conductive fibers required is small. By requiring fewer fibers, the color of the electrically conductive fibers in the fabric can be improved. This has the undesirable effect of bleaching the ball if it differs from the outer skin color of the ball. It is possible to avoid this. Furthermore, the weft, outer skin weaving) (turn and Another feature is that even when using stainless steel fiber, the board on the play without detracting from the desirable features of the system.

According to another feature of the invention, the tennis ball has an electrical conductivity much greater than that of water. to have high conductivity. Also, the ball detection circuit is installed on the tennis court. Although the presence of water is undetectable, it is Equipped with sufficient detection capability to detect threshold current. Therefore, this ability This prevents false signals from occurring due to the presence of water on the ball, while ensuring that the ball is , generates an appropriate signal when it goes down.

In view of the above explanation, the main object of the present invention is to provide a high electrical conductivity and an economical In addition, it can be manufactured to To provide a novel electrically conductive tennis ball that does not undesirably bleach the ball. Is Rukoto.

More specifically, the present invention provides a novel conductive tennis ball, comprising: The back side of the woven fabric or tennis ball cup (-) is covered with a conductive material 1, e.g. The electrical conductivity of woven fabrics can be improved by treating them with coatings, adhesives, cotton (linen) cloth, etc. The purpose is to provide a tennis ball made by electrically connecting fibers. Ru.

Another important object of the invention is to provide tennis balls with higher conductivity than water. The objective is to provide the following tools.

Yet another purpose is to sense the grounding of a conductive tennis ball.

To avoid false signals caused by water on the court.

The objective is to provide a new linesman system that does not detect water.

Brief description of the drawing FIG. 1 illustrates the present invention on a tennis court surface containing ball sensing conductors of an electric linesman device. A partially cutaway side view showing a state in which the ball is in contact with the ground; FIG. 2 shows a device used to detect ball contact in the linesman's device according to the present invention. Schematic diagram of the electric sensing circuit shown in Fig. 6 is a view taken along line 6-3 in Fig. 1; is an enlarged plan view showing part of the front side of the woven fabric that is the material of the ball cover; Figure 5 is a view taken along line 5-5 in Figure 4; Figure 6 is a view of the fabric shown in Figure 4. Figure 7 shows the weft threads for weaving; Figure 7 shows the orientation of the fibers after they are sewn; Enlarged cross-sectional view similar to Figure 5; FIG. 8 is a cross-sectional view taken along line 8--8 of FIG. 1; FIG. 9 is similar to FIG. is a sectional view showing another embodiment; FIG. 10 is similar to FIG. 8, but shows another embodiment. Cross-sectional view shown; FIG. 11 is a sectional view similar to FIG. 8 but showing still another embodiment; FIG. 12 is a cross-sectional view similar to FIG. 8, but according to yet another embodiment, showing some of the The conductive fibers have hanging ends that connect electrical connections between the cover panels. those positioned within the seams between cover panels to form continuity A cross-sectional view showing; FIG. 13 is a diagram similar to FIG. 4, but showing an alternative embodiment; FIG. 14 shows a tennis ball similar to FIG. 8 but with the cover shown in FIG. FIG.

Detailed description of the invention Referring to FIG. 1, an electrically conductive tennis ball embodying the principles of the invention is shown at 20. an inner elastically deformable hollow sphere or core 22 and two pieces of cover 24. It has Core 22 is of any suitable conventional construction, such as rubber or may be formed from other suitable elastically deformable materials. Inside core 22 The chamber may be filled with air or other gas under pressure.

The cover 24 is typically a belt or belt of woven fabric or cloth 30 (see FIG. 4). Die cut from the sheet and glued, affixed or otherwise attached to the outer surface of the core 22. It is divided into two figure eight or dumbbell panels 26.28 which are attached.

Any suitable electrical sensing circuit can detect the grounding of a tennis ball within a predetermined area of the court. Can be used in Baud/I/20 to detect baud/I/20. In Figure 2, the electrical detection circuit The simplified shape of the path is shown at 62 and includes a plurality of exposed and preferably parallel and spaced apart The conductor 34 is shown as having a conductor 34 of . The conductors of the sensing circuit are preferably flush with the surface 38. Embedded in the tennis court so that they lie side by side or y. In the illustrated example, Every other conductor of the sensing circuit 32 is electrically connected to one terminal of a suitable DC power source 67. and the remaining conductors of circuit 32 are electrically connected to other terminals of the power supply.

When the ball 20 contacts the surface 68, the ball 20 detects at least one of the sensing circuits 32. There is also a flat circular ground area large enough to bridge two adjacent conductors. It is deformed to form a repulsive region 40 (see FIG. 6). The conductor of the detection circuit 62 is , separated by a nominal distance defined by the flattened ground area 40 of the ball. . For example, the distance between adjacent conductors in one circuit 62 is 25.4 mm (1') in diameter. For a small ground contact area such as 4.76 m (3/16') may be sufficient. conductivity When ball 20 is grounded in an area occupied by five circuits 62, one circuit 32 of the sensing circuit, thus bridging two or more adjacent conductors of the sensing circuit. Complete a conductive circuit between two adjacent conductors.

Completion of the circuit across adjacent conductors of circuit 32 is from power source 37 via ball 20. It will lead to electric current. This current is caused by the ball being occupied by the conductor of circuit 32. The player operates the display device 41 to signal to the player that the player has landed in a predetermined area. used for

A preferred sensing circuit of the type described above is disclosed in U.S. Pat. No. 4,109, dated August 29, 1978. ．． No. 911, which patent is incorporated herein by reference.

Referring to FIGS. 4 and 5, the woven fabric 60 includes a plurality of wefts or filaments. A plurality of rows or parallel predetermined lengths of lines 46 extending perpendicularly to each other and interwoven. Warp threads 44 (or twisted threads as they are called when they are made) or warp threads as they are called. It is a unique satin weave with threads that can be mixed. Multiple rows of wefts or fillins The loom 46 is usually made into a single yarn ( or strands). Therefore, the parallel length of the weft These columns of .

Originally joined together by fabric selvedges, when cutting the panels from the fabric 30 are separated from each other at panels 26 and 28 of the cover.

In this specification, "yarn" refers to panels 26, 28 and 28 cut from fabric 30. used to refer to rows or parallel lengths of weft threads 46 in textile fabrics 30. Warp The separate parallel lengths of are also called yarns. In Figure 1, the parallel lengths of the warp and weft Lines indicating some of the threads are shown separated for illustrative purposes.

The actual spacing of the parallel lengths of the weft threads 46 is shown more accurately in FIG.

Referring to FIG. 8 and a small number of random lengths, such as a single untwisted synthetic fiber or monofilament type fiber. The fibers 50 are made of electrically conductive filaments. The conductive fiber 50 is a non-conductive fiber. are incorporated into the non-conductive fibers 48 so as to be distributed throughout the group. fiber After the fibers are blended, the fibers are combined as shown in FIG. Can be twisted together.

Non-conductive fibers 48 may be made of tennis balls, such as cotton and/or wool. may be formed from any suitable material used to construct covers for. electric Conductive fibers 50 are preferably thin, finely drawn stainless steel fibers.

Alternatively, the conductive fibers 50 are described in U.S. Pat. No. 4,299, dated Nov. 1, 1981. Silver or other electrically conductive materials, such as the plated or coated fibers disclosed in US Pat. It may also be a nylon fiber coated with material.

Preferably, the number of non-conductive fibers 48 is such that, in particular, the conductive fibers are different from the non-conductive fibers 48. If it is stainless steel or other material with color, the conductive fiber 5o considerably more than the number of

The conductive fibers account for 10% to 30% of the total number of conductive and non-conductive fibers in the yarn. A number that corresponds to an era may be used to indicate the number. In the illustrated embodiment, the non-conductive fibers 48 are not weft. The conductive fibers make up 70% of the total number of fibers in the filling and the remaining 30 make up %. After being woven, the fabric 6o has a cover with a suitable color, such as yellow. It may be dyed as desired. Schlegel Co., Rochester, New York ( Left Raco manufactured by Schlegel Corporation Lectra-Can 3-7093 yarn was wefted according to the above teachings. It may be used as a weft yarn when weaving the fabric 3o (alternatively, left Cone 36'0-150 conductive material is used to manufacture tennis ball covers. It may be used to make weft yarns such as the typically used yarns.

The parallel longitudinal sections or warp threads 44 are made entirely of nylon, cotton and/or wool. It is made of non-conductive fibers such as The warp fibers are untwisted synthetic single fibers. It can also be single fibers of discrete lengths, such as fibers or monofilament type fibers of a single composition ( , these single fibers are twisted together to form the warp threads used in the fabric 30. ing. Therefore, only the weft threads of the fabric 60 are electrically conductive, making the cover 24 of the ball electrically conductive. Contains fiber.

The warp strands 44 are very thin and the threads used for the weft 46 are approximately 10 times thicker than the warp. It is desirable that it be thick or coarse. Therefore, the weft yarns 46 have approximately 10 times more fibers than the warp yarns 44. has. For the weft, use a yarn with a Dtex of approximately 4400-5000. can be done.

The texture of the fabric 60 is of the conventional type used for tennis ball covers and each length, i.e. more than the weft threads 46 of each row pass under when viewed from the front of the fabric. It is advantageous that the shape is such that it passes over or skips over the warp strands 44 of It is.

The front side of the fabric 30 is shown in FIG. used as a side.

For each warp strand passing underneath, the weft threads 46 have five to seven warp threads. The top of strand 44 (i.e. the bottom of one warp strand and 5 to 7 strands) can pass through the upper part). Eight successive lines in the embodiment shown in FIG. For each group of warp strands 44, each row of weft yarns 46 consists of one warp strand. It passes through the bottom of the strand and the top of the other seven warp strands. For this type of organization Also, since the thickness of the weft threads 46 is much thicker, more weft threads (of By appearing on the surface, the weft thread 46 becomes dominant on the front side of the fabric 6o. It occupies most of the surface area on the top. For this fabric construction, weft 46 is a significantly larger area of the outer circumference of the tennis ball cover compared to the area occupied by the warp threads 44. It will occupy a large area. electrically non-conducting in each warp strand 46 The number of conductive fibers is large and the number of conductive fibers is relatively small, making it difficult to use in tennis ball covers. Stainless steel fibers etc. can be used in the weft without any undesirable discoloration. Wear.

After the weaving operation, the fabric 30 is conventionally subjected to pressure and heat to compress the woven fabric. It can be made into felt by

After felting, the fabric 60 is stitched to break conductive or non-conductive fibers. It is desirable to redraw a significant amount of electrical conductivity within the weft yarns 56 without causing damage to the warp yarns. 44 and the conductive fibers within the weft threads 46 are also stretched again by the stitching operation. Only the re-stretching of the conductive fibers is important.

Before the embroidery operation, the fibers in the warp threads 44 and the weft threads 46 are assembled as a whole as shown in FIG. Therefore, it is located within 600 planes of the fabric.

After the stitching operation, a large number of the conductive fibers 50 within the weft thread 46 are woven as shown in FIG. Portion 51 that has been re-stretched so as to extend across the entire 300 planes of the ground (Fig. 7) The conductive fibers 50 (including some free ends) are sewn by having Also the inside of the fabric whose part will be used as the inside or back side of the cover 24. Or it would extend beyond the plane of the fabric 60 on the back side. A lot of embroidery work 500 conductive fibers are connected to each other on both sides of the fabric or beyond the plane of the fabric on both sides. Do it so that it stretches.

Using a suitable embroidery machine with a fine or thin needle (not shown) Therefore, the fabric 60 can be sewn into the above shape. One of the suitable needle types is illustrated in patent no. 4,299.384. Instead, they face each other axially. By using a needle with a notch that The captured fibers are traversed from both sides or both sides of the fabric 6o. Cover 2 can be re-stretched so that it protrudes in the direction, or it can be fluffed and shirred on the top. It is advantageous for 4 to have a normal fuzz on its outer circumference. these After this operation, panels 26,28 are die cut from the fabric 60. felting, embroidery The sewing and fluffing process involves cutting the panel 26°28 from the fabric 30. However, it is recommended that you perform these operations before cutting the panel from the fabric. It is obvious that it is more convenient and economical to do so.

After being cut from the fabric, the panels 26, 28 are joined or glued to the ball core 22. let Use electrically non-conductive adhesives or cements for this purpose However, a conductive adhesive is preferable. The conductive adhesive is connected to the core 22. A thin layer 54 (see FIG. form). An example of a suitable conductive adhesive is one that is sufficient to obtain the desired conductivity of the ball. Purkan Co., Ltd. homogeneously mixed with a suitable amount of rubber cement for tennis ball manufacturing. Particulate carbon XC-72 is mentioned. Re-stretched by the embroidery process mentioned above The conductive and non-conductive fiber portions 51 are embedded in the adhesive layer 54 and bonded with the adhesive. It will be fixed or held in place.

Fibers 48.50 are twisted together for relatively long lengths to form the dead thread for weaving fabric 6o. Because of this, they are held in place and therefore do not loosen when exposed to impact forces while floating. It will not fall onto the court. Furthermore, it is re-stretched by the stitching process mentioned earlier. The retention force of the stretched fibers can be increased by embedding the re-stretched portion 51 in the adhesive layer 54. It will improve. Therefore, this structure prevents the conductive fibers from loosening and causing the sensing circuit. This avoids the inconvenient situation of falling on the Wear.

From the above, it can be seen that the conductive fibers 50 are distributed over the entire circumference of the ball in the conductive network 60 ( It will be understood that this creates the maze shown in Figure 1). The conductive network 60 runs inside the cover 24. A tennis ball extends along the outside of the street cover 24 and touches down onto the circuit 62. A circuit is completed between adjacent conductive wires in the detection circuit 62 when Forming a large number of conductive paths. The conductive network 60 portion located on the outer periphery of the cover 24 is touch the conductor of the detection circuit 62 by distributing it over the entire outer surface of the When the ball goes down, a signal will be generated regardless of the direction of the ball.

In addition to contacting the threaded portion of the fiber 500, the conductive adhesive layer 54 also . In the weft thread 46 portion looped under the warp thread 44 to appear on the back side of the cover 24. The needle is in contact with some of the conductive fibers that you want to thread.

Most networks 60 are therefore interconnected by electrically conductive adhesive layers 54. ing. This adhesive layer 54 is arranged entirely along the inside of the cover 24. Forms a conductive base.

The conductivity of the tennis ball to signal grounding of the ball to the detection circuit 32 is determined by the cover. - 24 and the conductive viscous interior of the cover 24. Due to the presence of the attached paste 54 and the large number of conductive fibers 50 due to the above-mentioned sewing operation, It increases considerably.

In the modified embodiment of the ball illustrated in FIG. 8, the adhesive layer 54 is non-conductive. can be made of materials. Thus, the conductive coating is formed by warp threads 44 and weft threads 46. It can be applied to the back side of the fabric.

This conductive coating substantially fills the spaces between the fibers of warp threads 44.

It performs the same function as the discharge conductive adhesive layer 54.

Referring to FIG. 9, seam 56 is conventionally formed between panels 26 and 28. There is. Conductive adhesive layer 54 ensures electrical continuity between panels 26 and 28. The sea urchin seam 56 is bridged.

Seam 56 is preferably filled with a suitable, conventional, non-conductive cement. another In embodiments, electrically conductive seam cement may be used, but the electrical conductivity in the cement may The conductive carbide causes undesirable discoloration of the ball. If panels 26 and 2 If 8 are closely matched, panels 26 and 28 will meet at the top of seam 56. to increase electrical continuity between panels 26 and 28.

In the embodiment shown in FIG. Sandwiched between them creates a conductive base for the back side of the cover 24. The scrim 58 is Unwoven open mesh tied in a uniform unwoven irregular array made of synthetic fiber. All fibers in scrim 58 are electrically conductive. is desirable. The scrim 58 extends around and covers the spherical surface of the core 22. ing. Scrim 58 is therefore.

It bridges the seam 56 and is disposed entirely between the core 22 and the cover 24.

Like the electrically conductive adhesive layer 54 described above, the scrim 58 also covers the stitched portions of the fibers 50. Several sections of the weft threads 46 are laid in contact with the warp threads 44 and are further looped under the warp threads 44. Contact some of the conductive fibers that are not sewn in place, and thus the scrim increases the conductivity of the balls and ensures electrical continuity between panels 26 and 28. Ru. The scrim 58 is attached to the core 22 and the cover 2 using a non-conductive adhesive or a conductive adhesive. It may be glued to 4. The scrim 58 is tightly pressed between the cover 24 and the core 22. will be allowed to do so.

Scrim 58 is a stretched sheet on the back or underside of panels 26 and 28. are located inside the scrim so that each panel and scrim composite can be conductive or non-conductive. It may be glued or cemented to the core 22 with adhesive. tennis bow The common non-conductive cement used to bond the ball cover to the ball core is It is considered to be one type of adhesive available. Scrim 58 further includes fabric 30 may be placed on the back or reverse side of the fabric 30 before being sewn together.

In the embodiment shown in FIG. It has been replaced by unused cloth or Matsutoro 2. The mat has cover 24 and and the core 220, and are bonded with conductive or non-conductive adhesive. It is glued. Matsutoro 2 can be made of any suitable material and has a cover 24 attached. It can be glued to the core 22 before it is removed. In the completed form of ball 20 The Matsutoro 2 has a sewn part of the conductive fiber 50 and a panel 26.2B. A portion of the filler 46 loops under the warp threads 44 to establish electrical continuity between the Touch some of the unstitched conductive fibers in the middle.

Instead of placing Matsutoro 2 over the core before placing the cover 24 on the core 22, Before the fabric is sewn and before the panels 26.28 are cut from the fabric, conductive or Glue with non-conductive adhesive.

Toro 2 can be glued to the back or opposite side of fabric 30. Is the panel woven fabric 30? After being cut out, the panel/mat composite is bonded with conductive or non-conductive adhesive. can be adhered to the core 22.

Instead of using the scrim 58 or Matsutro 2, the back side of the fabric 30 (toe (the inside side of the cover 24) after the fabric 60 has been sewn in the manner described and as desired. Preferably after the fabric has been fluffed and the panels 26, 28 are cut from the fabric. before.

The entire surface can be covered with a conductive coating 64. coating 64 has sufficient thickness and redistribution of the sewn fibers including fiber 50. The oriented portion is embedded and fixed in the coating 64 to increase the conductivity of the ball. coated in this manner. Furthermore, the coating 64 is partially applied to the fabric 30 on its back side. conductive unstitched weft fibers that have entered the fabric and are still present on 600 sides of the fabric. 50 are electrically connected.

The coating 64 may be of a general type and may be of any suitable type. Ru. For example, coating 64 may include latex from Schliegel Coholage, Inc. The base coating can be R3115-00-2.

After the coating 64 has been applied, the panels 26.28 are then formed from the fabric 60 using a die. It is cut out from Thus, the coating 64 is similar to that which the panel is cut from the fabric 60. 26, 28, a continuous and uninterrupted Form a conductive base material.

Alternatively, the coating 64 is applied after the panels 26.28 are cut from the fabric 60. They can also be coated.

When cut from the coated fabric, the panels 26.28 can be electrically conductive or non-conductive. It is adhered to the core 22 of the ball with an adhesive.

The electrical conductivity between the panels 26, 28 is such that significant electrically conductive fibers 50 are present at the ends of each panel. The panel is woven into a fabric in such a way as to leave the edges 66 (FIG. 12) hanging from the top. This is achieved by separating the This means that panels 26.28 can be By cutting the fabric 30 in sections (i.e., cutting the fabric only at the periphery of each panel) cut or partially cut each in separate areas) until the panels are completely separated from the fabric. The edges 66 are uncut in such a way that they hang from the edges of each panel in the uncut areas. This can be accomplished by pulling a completely cut panel from the rest of the fabric.

When gluing panels 26 and 28 in place over the core of the ball, the two panels The dangling end 66 from the panel provides a conductive passageway that fills the seam between the two panels. combined or entangled to form a End 66 is covered with suture adhesive 67 (FIG. 12) or embedded in other material filling the seam 56.

Fixed in place in suture adhesive. If desired, suture adhesive Even if it is an electric conductor, it is good.

Utilizing fiber ends 66 to establish electrical conductivity between panels 26 and 28 and by utilizing conductive longitudinal strands, the basis of conductivity (i.e., Adhesive 54. The scrim 58 or Matsutoro 2) can be omitted from the ball, and the cover 2 4 can be adhered to the core 22 with a non-conductive adhesive. Butt each other at the top of the seam The close alignment of panels 26 and 28 also reduces the distance between panels 26 and 28. In this case, the ends 66 hanging on the panel and the conductive Seam filling pace is no longer required.

According to another feature of the invention, the conductive network 60 is significantly more conductive than water. , the ball detection circuit 62 is configured so as not to detect water on the tennis court surface. Ru. This is achieved by placing a variable resistor 76 (see Figure 2) in series with the power supply 76. achieved. Alternatively, water between adjacent conductors in a circuit 62 may The resulting false signal is made insufficient to change the output of the comparator and the ball is A comparator is used to compare the generated electrical signal with a fixed reference signal. (not shown) can be used. However, the more conductive tennis ball The stronger signal generated by the Notifies that the ball has landed within the designated area.

The resistivity (bidirectional conductivity) of the conductive tennis ball according to the present invention is per square inch. Preferably, the resistance is between 10 and 500 ohms.

In FIGS. 13 and 4, the alternately woven cloth 30a is used as the cover 24. may be used. This is because the warply twisted yarns in the cloth 50a, that is, the strands 44a are conductive fibers. The conductivity of the ball is increased by adding a scrim or conductive coating. It is the same as cloth 30 except that no glue or conductive adhesive is required.

The filling threads in fabric 50a are the same as the filling threads in fabric 60. In these two cloths Similar filler thread elements are similarly numbered.

In the embodiment shown in FIGS. 13 and 14, the conductive fiber 50a has many non-conductive Fibers 48a are mixed, and the mixed fibers are twisted together to form warp-twisted yarn 4. It forms the twisted part of 4a. Ratio of conductive fibers to non-conductive fibers in the warp twist yarn 44a The ratio is less than the ratio of conductive fibers to non-conductive fibers in the filler threads 46, however. These ratios may be the same, or the ratio of the twisted yarn 44a may be larger. stomach. Preferably, fiber 50a is the same as fiber 50. Further, the fiber 48a is the fiber 4 It may be the same as 8. The weaving pattern of cloth 30a is the same as cloth 60.

In this Specification C (including the following claims), the term "thread" refers to sewing thread and other It is thought to contain threads of the form.

The sewing thread is here considered to be a "thread" that is significantly twisted.

This invention may be embodied in other forms without departing from the technical scope of the invention. Of course it can be done. Therefore, the non-inventive embodiments include all described elements. However, it is not limited to this. The technical scope of the invention is as described above. is determined by the claims appended hereto and not by the description thereof, and accordingly Changes within the range of equivalents are included within the scope of the present invention.

Jusho (no change in content) Procedural amendment (j5ka) 1. Display of incidents pCT/US87101118 2. Name of the invention Conductive tennis ball and line judgment device 3, person making correction Relationship to the incident: Patent applicant address Name: Van Auken, John A4, Agent Address: Shin-Otemachi Building, 2-2-1 Otemachi, Chiyoda-ku, Tokyo, 2℃6 Ward Phone 270-6'641-6646 5. Date of amendment order: December 19, 1999 (Shipping port) 6. Subject of amendment (1) Power of attorney and translation international search report 1″’″″“-IAj″””””’PCT/US87ノ0111onlyPCT/US 87101118 Attachmen? orrn　PCT　xSA/210　Part V engineering, engineering.

Te1ephan@approval+5140 payment appro ved by Rlcharl D, Muster on9 July 19 137 for Group XXI charg@to Deposit A ccount? io, 08-3260 Counsel advised th at he has no right *.

pro hest for any group not paid for: and that any protestanus be filed no Later%han 15 days from the date of available of 5earch report (Form 210).

Reasons for holding 1ack of unity 1n vention：The 1st venture dafinad by cla ims 1-17 of Group does not require the particular tennis ball damned by claims 1B-31 of Group, as evidenced by the presence of claio+ L and the particular tennis ball of Group XXob violently can be usea wish 1ine callin g systems other I-he ooe 1include d in the claims of Group, Al5o.

Seha 1nvenhi 1ons of Groups X and ar e　5eparatelyclassify4. as noted above e.

Ti+ne Lim1t PorFLlin Pro seest protest of the holding of 1ack of unity of 1 innovation.

Engineering accordance with PCT Ru1a 40.2. ap plicant may protect the holding of 1a ck of unity only with respect to the group(sl paid for.

Claims (3)

[Claims] 1. Conductive tennis pole with pre-selected conductivity and selection on tennis court an electric detection device comprising a circuit for detecting that the ball has fallen into the area; and means for preventing electrical detection of water present on the court. Tennis court warning device. 2. extending along the selected area of the tennis court and/or the top of the net; A conductive tennis ball that forms a current path between conductive objects located at a distance, The conductive tennis pole has an elastically deformable sphere and a woven cloth cover that covers the sphere. has, and the woven fabric is uniform over the entire surface of the pole and (a) is interwoven with each other; has a strand of warp-twisted yarn and a strand of horizontally-twisted yarn that are orthogonal to each other, and one of said strands Twisted yarn or multiple conductive fibers with metallic surfaces twisted together formed from non-conductive fibers, and in the yarn for said one strand said The number of the non-conductive fibers is set to such an extent that discoloration of the cover due to the conductive fibers is prevented. (b) vertical strands and horizontal strands organized with each other; strands, one of the strands having a metal surface and an arbitrary length. It consists of electrical fibers and non-conductive fibers mixed with the electrically conductive fibers, and the electrically conductive fibers and non-conductive fibers are and non-conductive fibers are twisted together to form said one strand. A conductive tennis ball characterized by: 3. A circuit extends along a preselected area and between spaced conductive objects. The electric field detects that the ball has fallen into the area by forming a A conductive tennis ball used with a detection circuit, wherein the tennis pole is elastically modified. It has a shapeable sphere and a cover made of woven fabric that covers the spherical body, and the woven fabric comprises: It consists of vertical strands and horizontal strands that are arranged with each other, and one of the strands is One strand is made of conductive fibers and non-conductive fibers, while the other strand is made of conductive fibers and non-conductive fibers. A conductive tennis ball characterized by being entirely made of non-conductive fibers.