Note: Descriptions are shown in the official language in which they were submitted.
CA 02696881 2010-02-17
Device and Method for Controlling the Striking Accuracy
of a Golf Club
The invention relates to a device and a method=for
controlling the accuracy with which the striking face of a club
head of a golf club strikes a golf ball.
In putting in particular it is important that the putter
used for this is accurately guided, so that it strikes the golf
ball with the ideal spot on the striking face, the so-called
sweet spot, taking into consideration the center of gravity.
The situation is similar in chipping and pitching.
Normally, it is only possible to detect from the result
of a multitude of putts, whether a golfer has mastered the
putting techniques and regularly strikes the sweet spot.
Occasionally a camera is used as an aid in order to optimize
the sequence of movements, but taking pictures and evaluating
the film is time- consuming and entails great costs, so that
this can only be considered to be a temporary step. Prior to
each putt it is also possible to apply a foil, which becomes
discolored under pressure, to the face of the putter, and
thereafter to evaluate the sequence of foils. This method is
also much too cumbersome for being practiced over an extended
period of time.
Finally, a golf club is sold by Alan Electronics GmbH,
63303 Dreieich, internet address www.dixxgolf.de, designated
"DiXX Digital Instruction Putter", which offers the possibility
of selectively fastening a housing on the back of the club
head, which contains acceleration sensors, an electronic
measuring and evaluation device and a flat image screen, or a
weight, which is as heavy as this unit, in an exchangeable
manner. The acceleration sensors are suitable to detect
several parameters of the movement of the golf club in the
course of a club swing, inter alia also the position of the
impact point on the one or the other side of the sweet spot.
However, an exact determination of the actual point on the
striking face with which the ball was struck is not possible
with such a measuring method.
It is therefore the object of the invention to provide a
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device of the type mentioned at the outset, which can be
attached to a customary golf club without substantially
changing its properties, does not require interfering actions
during play only for purposes of measurement, registers the
impact point on the golf ball more exactly than up to now, and
represents the recorded results of the measurement, after
having been evaluated in accordance with a program, in a form
in which they are available at any time.
The above object is attained by the invention by means
of a device comprising
- a plate-shaped sensor, which can be releasably
fastened on the striking face in a defined position, by means
of which the exact point of the position of the impact point in
the course of striking a golf ball can be localized,
- a housing, which can be releasably fastened on the
shaft or on the back of the head of the golf club, containing
an electrical voltage source and an electronic measuring and
computing circuit, which acts together with the sensor via
signal lines, by means of which a measuring process for
determining the coordinates of the impact point in relation to
the position of a predetermined reference point can be
performed in the course of each impact on a golf ball, and
- a radio module, connected with the measuring and
computing circuit, for the wireless transmission of the results
of the measurements to an evaluation device in the nature of a
cell phone, smart phone or PDA for the program-controlled
evaluation and display of the results of the measurements on
its display screen.
The plate-shaped sensor is so light and thin that it can
practically not be felt when a stroke is performed. Because of
the application to the striking face of the golf club, and not
to its back, each impact point is being registered very
precisely. The measuring and computing circuit, which can
preferably be fastened to the shaft of the golf club, increases
its weight only minimally, because it needs to perform only the
functions required for controlling the measuring processes and
for determining the coordinates of the impact point and to
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transmit the results of the measurements by radio to a cell
phone or smart phone, for example. They can be stored there
and evaluated by means of suitable programs. In most cases, a
cell phone, smart phone or the like, is available anyway and is
regularly taken to the golf course. Suitable programs for
evaluating the results of the measurements can be made
available via the internet for downloading to the cell phone or
smart phone. Directly following a stroke it is thus possible
to read on the display of the cell phone which point on the
striking face had connected with the ball. Then the player can
already attempt in the course of the next stroke to correct a
possible error in holding and guiding the club. Furthermore,
he can pick up the cell phone at any time, for example during
train travel or in a restaurant, and, alone or together with
other golfers, can examine the grades of accuracy of the hits
collected over an extended period of time, evaluated and
represented in diagrams, for example, compare them with other
players and discuss them.
The plate-shaped sensor is preferably constructed in the
manner of a computer touchpad, with a rectangular support plate
having a first electrically conductive layer applied to its
front which is connected along two oppositely located edge
areas with respective printed strip conductors, which are
connected to a signal line, and with a flexible protective
plate, to whose back a second electrically conductive layer has
been applied which is connected along two oppositely located
edge areas with respective printed strip conductors, which are
connected to a signal line and extend transversely in respect
to the strip conductors connected with the first conductive
layer, wherein the conductive layers are separated by means of
elastic spacers, whose restoring force has been selected in
such a way that there is a temporary contact between the
conductive layers only when a golf ball strikes an impact
point.
Such a touchpad has been described in USP 6,238,790 Bl,
for example, to which, for the sake of simplicity, reference is
made regarding the explanation of the functioning of the above
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characterized sensor. However, it should be noted here that a
computer touchpad, for example on a laptop, is intended to be
fixedly mounted in the housing of the computer and is touched
by fingers relatively lightly and slowly. In contrast thereto,
the sensor of the measuring device in accordance with the
invention is mechanically stressed to a much greater degree
when striking a hard golf ball. Moreover, other demands are
made on the sensor because, in contrast to a computer touchpad,
it is intended to be easily releasable from the support
surface.
It has been surprisingly shown that, in spite of the
greater, shock-like stress in comparison to a touchpad, when
the same materials are used, the solution of problems resulting
from the different conditions does not lie in a thicker, or
respectively stronger design of the sensor, but just the
opposite, in a reduction of the plate thickness. While in a
touchpad of the type mentioned, the support plate normally has
a thickness of approximately 1.6 mm, the support plate of the
novel sensor can be about half as thick, because it is
supported over the entire surface on the striking face of the
golf club, so that a greater thickness is not required.
Simultaneously with the reduction of the thickness of
the support plate, the advantage is attained that it, and with
it the plate-shaped sensor, becomes more flexible, so that it
can be more easily removed if it is fixed on the striking face
of the golf club by means of a foil, which is adhesive on both
sides.
A further difference between the sensor of the proposed
measuring device and a computer touchpad consists in that the
support plate of the touchpad is provided with strip conductors
on its back, or respectively underside, and supports electronic
components. In contrast thereto, the sensor electronics of the
proposed sensor are located in the housing of the measuring and
computing circuit, which is preferably attached to the shaft of
the golf club. The thinner support plate and the transfer of
the sensor electronics to the club shaft have the further
advantageous result that the entire plate-shaped sensor only
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CA 02696881 2010-02-17
needs to have a thickness of approximately 1 to 2 mm, so that
therefore the striking face of the golf club is only minimally
displaced forward.
More than a computer touchpad, the sensor of the novel
device is exposed to changing temperatures and to moisture. It
is therefore useful that the protective plate is solidly and
sealingly connected in a material-to-material manner in the
edge area with the support plate, for example glued together
with it, except for an air inlet and outlet opening. The air
inlet and outlet opening can be covered by means of a water-
tight, but air- permeable foil, or sealed by a cover, such as
in a labyrinth seal, for example, in such a way that the sensor
is at least protected against dust and splashed water in
accordance with IP54.
Tests have shown that the active sensor surface only
needs to be approximately 45 to 55 mm wide, and for putters
approximately 16 to 20 mm high, for clubs for pitching and
chipping 20 to 30 mm high. Preferably the sweet spot is
located in the center.
It furthermore appears to be useful that the signal
lines between the sensor and the measuring and computing
circuit have a plug connection which can be released. This
permits the separate application and replacement of the
respective two units on the golf club. Preferably, the one
half of the plug connection is fixedly attached to the housing
{ of the measuring and computing circuit or fixed on the support
plate, while the other half of the plug connection is located
at the free end of a cable. A multitude of embodiment
variations are available for fastening this housing on the
shaft of the golf club. It may already be sufficient to fix
the housing in a frictionally connected manner by means of at
least one clamp or one clamping strap, wherein a rubber-like
contact face or intermediate layer is advantageous.
An exemplary embodiment of the invention will be
described in greater detail in what follows by means of the
drawings. Shown are in:
Fig. 1, a schematic representation of the total
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configuration of the proposed device,
Fig. 2, a simplified cross section through a sensor,
Fig. 3, an equivalent circuit diagram of the sensor,
Fig. 4, the essential elements of the sensor electronics
attached to the club shaft, and
Fig. 5, a simplified cross section of the housing of the
sensor electronics and the club shaft at an attachment
location.
A golf club is represented in Fig. 1, whose club head is
identified by 10, the shaft by 12 and the grip by 14. A sensor
18, which will be explained in greater detail in what follows,
is fastened on the striking face 16 of the club head, and its
actively sensitive surface is identified by 20. Here, the
directions of the subsequently employed coordinates x, y and z
have also been drawn in. Their common point of origin is
located in the sweet spot 22 of the striking face 16.
The sensor 18 is connected via a plug connection 24 and
signal lines 26, combined to form a cable, with sensor
electronics, identified as a whole by 30, having a measuring
and computing circuit and being mounted in a protective housing
28, which is attached to the shaft 12 by means of an easily
releasable fastening mechanism 32, and is in contact via a
radio module 34, preferably Bluetooth, with a mobile evaluating
device 36 in the nature of a cell phone, smart phone or PDA,
whose corresponding radio module is identified by 38, a flat
display screen with 40 and a keyboard by 42. If desired, a
laptop can also be employed as the evaluating device 36.
The x- and y-coordinates of the impact point of a golf
ball in relation to the sweet spot 22, determined by the
measuring and computing circuit 30 and registered accurately to
a point by the sensor 18, together with the coordinates of the
impact points of further ball strikes, are evaluated in the
evaluating device 36 under program control and are graphically
displayed.
The sensor 18 is of the structure represented in Fig. 2.
It consists of a support plate 48, which can be fastened by
means of a foil 46, adhesive on both sides, on the striking
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face 16, as well as a protective plate 50, arranged on the
outside in front of the support plate 48. For example, the
support plate 48 can be made of fiberglass-reinforced epoxy
resin (preferably FR4 or FR5). The protective plate 50 can be
made of a plastic material (preferably polyester) . Foils,
commercially available under the marks Tesa, Herma or Scotch,
can be considered for the foil 46 with adhesive on both sides,
in which case the adhesive force is preferably slightly greater
ori the side connected with the support plate 48 than on the
side to be connected with the striking face 16.
On their facing insides, the support plate 48 and the
protective plate 50 are each provided with an electrically
conductive layer 52, or respectively 54. These can be
semiconductor layers in accordance with USP 6,239,790 Bl, which
have a defined linear resistance. Spacers 56 of sufficient
size and sufficiently distributed are arranged between the two
electrically conductive layers 52 and 54, which see to it that
the conductive layers 52, 54 only touch each other if a
sufficient pressure is regionally, or at points, exerted on the
flexible protective plate 50, for example when struck by a golf
ball. As indicated at 58, the protective plate 50 is fixedly
glued together with the support plate 48 along the edge areas,
but wherein at least one air inlet and outlet opening, not
represented, remains open and is designed in the manner of a
labyrinth seal, so that the sensor is protected against dust
and splashed water in accordance with IP54.
Also not represented are two printed strip conductors,
which extend along oppositely located edge areas of the support
plate 48 and are electrically connected over their length with
the conductive layer 52. On its interior, the support plate 48
is provided with two further printed strip conductors, which
extend along oppositely located edge areas at right angles in
respect to the first mentioned strip conductors and which, in
the assembled state, contact the electrically conductive layer
54 on the protective plate 50 over their length.
Alternatively, the strip conductors which are electrically
connected with the conductive layer 54 can also be printed on
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the protective plate 50. Each one of the four strip conductors
is connected with the measuring and computing circuit 30 via a
signal line, which continues in the cable 26.
If the flexible protective plate 50 is sufficiently far
indented at one location, so that the conductive layer 54
touches the other conductive layer 52 on the support plate 48,
it is possible, following the application of a defined
reference voltage to the strip conductors connected to one of
the two layers, to measure a voltage between the strip
conductors connected with the respective other layer, which
rises, or respectively falls, proportionally to a change in the
distance of the impact point from the strip conductors charged
wi_th the reference voltage, so that, following a calibration,
it is also possible to determine the x- and y-coordinates.
In connection with the computer touchpad of USP
6,239,790 Bl, the distances of a pressure point from the strip
conductors, which are arranged at right angles in respect to
each other, are calculated on the basis of the length of time
required by the current for charging defined capacitors
connected to the strip conductors. An increased path of the
current through one of the conductive layers is equivalent to
an increased resistance, i.e. a reduced current strength, and
therefore a longer period of time needed for charging the
respective capacitor.
In contrast thereto, for working with the novel sensor a
different, more rapid measuring method is provided because of
the shock-like loads. For this purpose, reference is made to
the equivalent circuit diagram in Fig. 3, in which the strip
conductors identified by Yl and Yr are arranged at the left, or
respectively right, edge of the conductive layer 52, for
example, the strip conductors identified by Zo and Zu are
arranged at the upper, or respectively lower edge of the
conductive layer 54, the fixed resistors assigned to the
respective strip conductors are identified by Ryr, Ryl, Rzo and
Rzu, and the resistors in the kQ- range of the conductive layer
52, or respectively the layer 54, respectively between the
impact point and the four strip conductors, are identified by
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Rya, Ryb, as well as Rza and Rzb.
Without contact between the two layers 52, 54 at the
impact point, the resistance between a strip conductor of the
layer 52 and a strip conductor of the layer 54 is infinite
because of the spacers 56. If a sufficiently large pressure is
exerted on the protective plate 50 at a point, the two layers
52, 54 constitute the resistance network represented in Fig. 3.
For the determination of the coordinates of the impact point
of a golf ball, a defined reference voltage Vref is
alternatingly applied during the strike between Yl and Yr, as
well as between Zo and Zu, and the voltage drop is
simultaneously measured with high- impedance at one end of the
other layer. As can be seen, the measured voltages between Zu
and Yr
Vz = Vref x (Rzb+ Rzu)/(Rzo+Rza+Rzb+ Rzu) and
respectively between Yl and Zo
Vy = Vref x (Rya+Ryl)/(Ryl+Rya+Ryb+Ryr) are proportional
to the position of the impact point in the Z- and Y-directions
on the sensor face. By measuring the voltages in case of
pressure on, for example four, registration markers 44,
arranged symmetrically around the zero point 22 of the
coordinate system, which have been imprinted on the support
plate 50 at defined spacings in the area of the active sensor
face, it is possible to determine the relationship between
voltage and spacing, and the sensor can be calibrated in this
way, so that from the voltage values a conversion into mm of
the position relative to the zero point 22 of the coordinate
system placed on the sweet spot is possible.
The measurements are continuously performed at a
suitable scanning frequency between lkH and 4kH, preferably at
2kH, in order to be able to definitely determine the position
of an impact point in both coordinate directions during the
length of the pressure. Furthermore, the time of the striking
of the golf ball and the length of pressure can be determined
in that valid measurement values can be differentiated from 0
Volt by means of the constant end resistors Ryl, Ryr, Rzo and
Rzu. For the z-axis, the voltages which can be measured when
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pressure is exerted are between
Vref x (Rzo+Rza+Rzb)/(Rzo+Rza+Rzb+Rzu) Volt, and
Vref x Rzu/(Rzo+Rza+Rzb+Rzu) Volt, and for the y-axis
between
Vref x (Ryl+Rya+Ryb)/(Ryl+Rya+Ryb+Ryr) Volt, and
Vref x Ryr/(Ryl+Rya+Ryb+Ryr) Volt. Scanning is
performed at 8bit to 12bit, preferably at 10bit.
In Fig. 4, the essential parts of the measuring and
computing circuit 30 are represented. They are attached to a
board 60 in the housing 28 and are interconnected in the
customary manner.
Most important is a micro-computer, identified by 62,
having RAM, a FLASH memory, A/D converters, inputs and outputs
(GPIOs) and a serial interface, preferably UART and SPI. The
micro-computer 62 controls the application of the reference
voltage to the signal lines, which are connected with the
electrically conductive layers 52, 54, registers the voltages
measured in the course of the measuring process and the
associated times, and calculates the coordinates of the impact
points. These are intermediately stored and are passed on to
the evaluating device 36 via the radio module 34 with an
aerial, preferably a ceramic aerial 35. A battery 64 is used
for the electrical current supply, whose charging regulator is
represented at 66. Charging takes place through a jack 68,
preferably an USB jack of the type Mini-B, or a 2.5 mm jack
bush. The micro-computer 62 can also be reprogrammed via this
jack.
A quick-fastening mechanism for the releasable fastening
of the housing 28 of the measuring and computing circuit 30 on
the shaft 12 of the golf club is represented in Fig. 5 which,
in accordance with Fig. 1, is preferably located on the side of
the shaft 12 opposite the club head 10, or on the side opposite
the striking face 16. As represented, on the side resting
against the shaft 12 the housing 28 is cut out in a channel-
like manner with a diameter slightly larger than the shaft
diameter. A rubber insert 70 has been placed between the
housing 28 and the shaft 12, which can also be glued to the
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housing 28 and can aid in protecting the housing against dust
and splashing water in accordance with IP54. The connection of
the housing with the shaft 12 takes place by means of a
flexible plastic shackle or a clamping strip 72, for example a
textile strip, each of which can be rubberized on the inside.
The one end of the clamping strip 72 is fixed on a deflection
pin 74 connected with the housing 28. On the side of the
housing 28 located opposite the deflection pin, the clamping
strip placed around the shaft 12 is connected with a clamping
or arresting lever 76, which engages a cutout 78 of the housing
28 and clamps the clamping strip 72 in the course of its
closing movement. It is understood that a multitude of other
mechanisms for fastening the housing 28 on the shaft 12 exists,
for example hooks on at least one side of the housing 28, into
which the rubber clamping strips, which have been passed around
the opposite side of the shaft 12, are hooked.
The evaluating device 36 operates in the master mode in
order to receive, when required, the measurement data from
several measuring and computer circuits 30 which, for example,
are each transmitted via Bluetooth, or a suitable transmission
protocol, preferably SPP or HDI, to the evaluating device 30,
to store them, evaluate them and to display them. It is
possible in this way for two or four players, for example, to
directly compare their evaluated data with each other on a
common curve diagram.
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