Golf swing analysis methods

Details Golf swing analysis methods Golf swing analysis methods

1998-12-04

2001-05-08

Young, Lee (Department: 3729)

Games using tangible projectile

Golf

Practice swingable implement or indicator associated with...

C473S222000, C473S225000, C473S233000, C473S257000

Reexamination Certificate

active

06227984

ABSTRACT:

TECHNICAL FIELD
This invention relates to golf club swing analyzers and golf swing analysis methods.
BACKGROUND OF THE INVENTION
Electronic golf swing analyzers have been used to assist people with monitoring characteristics of their individual golf swing. Some configurations generally use some form of light detector (e.g., phototransistor, photo cell, etc.) as a sensor for use in swing analysis. However, the prior art designs suffer from the same limitation wherein they perform adequately indoors with a stationary overhead light source, but fail to operate properly when utilized outdoors. More specifically, measurements of conventional swing analyzers become erratic and inaccurate in the presence of the moving sun during outdoor use. These machines are not reliable when used outdoors.
Referring to
FIG. 1
, one conventional optoelectronic golf swing analyzer configuration is shown. An array of light sensors
12
is imbedded in a hitting platform
10
in reasonably close proximity to a golf ball
11
to be struck by an approaching golf club
14
. A lamp
13
is mounted in a fixed position above sensor array
12
to provide a source of infrared light for sensor array
12
.
As the clubhead of golf club
14
approaches golf ball
11
, the light is blocked from some of the sensors of array
12
and this condition is subsequently detected. Sensor array
12
is arranged in a specific pattern that allows detection of the position and timing of the clubhead of club
14
in the impact area of golf ball
11
. From this data, important information about the golf swing can be calculated and displayed. For example, clubhead path, clubface angle, clubbead speed, impact point of ball upon the clubface, tempo or swing time, ball velocity and ball carry are exemplary parameters which may be calculated and displayed to the user.
The type of device illustrated in
FIG. 1
functions properly when used indoors with a fixed overhead light source, such as lamp
13
. However, when the device is used outdoors and especially in the sun, several factors have a negative influence on performance which preclude accurate detection of clubhead timing and position.
FIG. 2
shows a typical sensor circuit for a conventional optoelectronic swing analyzer arrangement. The depicted circuit comprises a light detector
21
coupled with a resistor
22
and comparator circuit
23
. A steady state source of light
20
from lamp
13
(not shown) illuminates light detector
21
which provides a high signal output (+V) due to the light current flowing through resistor
22
. When the clubhead passes over light detector
21
, the light current is reduced and the output signal goes to a logic low (0) state. The output signal is routed to logic gate or comparator
23
which detects this change in output signal from resistor
22
. The change in the output signal indicates the passage of the clubhead.
Referring to FIG.
3
-
FIG. 5
, problems typically experienced with the utilization of such conventional devices in the outdoors is illustrated. If the analyzer is exposed to the sun, device operation becomes erratic inasmuch as sunlight contains more intense infrared energy than the overhead lamp. Thus, sensors
21
tend to respond to the presence or absence of sunlight.
Further, other sources of error can be attributed to the fact that the sun is constantly moving such that the light source for the detectors comes from many different directions depending upon the time of day. A plurality of sensors
21
are sequentially labeled
1
thru
13
in FIG.
3
-FIG.
5
. The sun is directly overhead in the illustration of FIG.
3
and plural light rays
30
therefrom radiate straight down casting a shadow
31
directly under the clubhead of club
14
. Sensors
21
numbered
4
thru
8
are blocked from light
30
in FIG.
3
.
The position of the sun in
FIG. 4
is to the right of club
14
and light rays
30
are angled from right to left in a downward direction creating shadow
31
that lags the clubhead of club
14
(assuming the clubhead is moving from left to right in FIG.
4
). Sensors
21
numbered 1 thru 6 are blocked from the sun in
FIG. 4
although the position of the clubhead of club
14
with respect to sensors
21
is identical in FIG.
3
-FIG.
5
.
The sun is to the left of club
14
in
FIG. 5
with light rays
30
angled from left to right in a downward direction creating shadow
31
that leads clubhead
14
(again assuming movement of the club in a direction from left to right). Sensors
21
numbered 6 thru 12 are blocked from light
30
from the sun in this case.
Although clubhead
14
is in the same exact position in the above illustrations with respect to sensors
21
, the actual sensors
21
that are blocked from the light source (e.g., the sun) change as the light source moves. This creates errors in measurement of clubhead position. Furthermore, any given sensor
21
is blocked from the light source at a different time during the swing as the sun moves across the sky. This creates errors in timing measurements.
The problem is further complicated by the fact that the intensity of the light seen by the sensors
21
also changes as the sun moves. The light is most intense when the sun is directly above sensors
21
as shown in
FIG. 3
, and least intense in the morning and evening hours corresponding to FIG.
4
and FIG.
5
. Other sources of measurement errors include reflections of light from the leading edge of the clubhead and shadows cast by nearby objects across the array of sensors
21
.
One way to reduce problems associated with the use of conventional devices outdoors includes completely shading all sensors
21
of this type analyzer from sunlight so that only light from overhead light
13
reaches the light detectors
21
. Such could include using the analyzer in a tent with the associated costs and inconvenience.
As is readily apparent, the above configurations prove problematic in a prime desired application of the analyzer—use outdoors. Further, the suggested solutions have associated drawbacks which reduce the attractiveness or feasibility of utilizing the conventional devices outdoors.
Referring to FIG.
6
and
FIG. 7
, another technique used in some conventional configurations to detect a clubhead is illustrated. An emitter
34
is positioned to radiate a steady beam of light
35
in an upward direction. When the clubhead of club
14
passes over light
35
, a portion of the light is reflected down and increases the light current through a phototransistor
37
which produces a voltage response across an associated resistor
38
.
These circuit configurations will typically not operate properly in direct sunlight because infrared energy emitted from the sun is much more intense than that of emitter
34
. Accordingly, any change in phototransistor current caused by sunlight will overpower any small change in current due to reflected light energy
35
.
Some devices have been designed to use horizontal beams of light energy in an effort to overcome problems caused by sunlight. The emitters and detectors are housed in boxes that protect associated sensors from direct sunlight. Such sensors are typically configured to detect the moment a clubhead breaks a horizontal beam of light. There are a number of patents that describe such devices, including U.S. Pat. No. 5,692,966, U.S. Pat. No. 5,257,084, U.S. Pat. No. 5,324,039 and U.S. Pat. No. 5,087,047.
A significant drawback with these designs is that the devices are usually restricted to calculating timing measurements of the moving clubhead without providing position measurements. Therefore, such devices are limited to measuring clubhead speed and tempo. Additional important swing parameters such as clubhead path, clubface angle and the impact point of the ball on the clubface require position information of the clubhead.
Therefore, a need exists to provide a sensing system and methodologies that overcome the limitations of the above-described configurations, and produce accurate measurements both indoors and outdoors, and during night or day.


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