U.S. patent application number 12/427049 was filed with the patent office on 2009-08-13 for method to determine hold over ballistic information.
This patent application is currently assigned to Bushnell Inc.. Invention is credited to John Cross, Jordan Vermillion.
Application Number | 20090199453 12/427049 |
Document ID | / |
Family ID | 37890754 |
Filed Date | 2009-08-13 |
United States Patent
Application |
20090199453 |
Kind Code |
A1 |
Cross; John ; et
al. |
August 13, 2009 |
METHOD TO DETERMINE HOLD OVER BALLISTIC INFORMATION
Abstract
A handheld rangefinder device operable to determine ballistic
hold over information is disclosed. The rangefinder device
generally includes a range sensor operable to determine a first
range to a target, a tilt sensor operable to determine an angle to
the target relative to the device, and a computing element, coupled
with the range sensor and the tilt sensor, operable to determine a
hold over value based on the first range and the determined angle.
Such a configuration facilitates accurate firearm and bow use by
providing ranges and hold over values without requiring
time-consuming and manual user calculations.
Inventors: |
Cross; John; (Overland Park,
KS) ; Vermillion; Jordan; (Overland Park,
KS) |
Correspondence
Address: |
HOVEY WILLIAMS LLP
10801 Mastin Blvd., Suite 1000
Overland Park
KS
66210
US
|
Assignee: |
Bushnell Inc.
Overland Park
KS
|
Family ID: |
37890754 |
Appl. No.: |
12/427049 |
Filed: |
April 21, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11314593 |
Dec 21, 2005 |
|
|
|
12427049 |
|
|
|
|
Current U.S.
Class: |
42/142 ;
434/27 |
Current CPC
Class: |
G01C 3/08 20130101; F41G
1/473 20130101; G01S 17/86 20200101; F41G 3/02 20130101; G01S 7/497
20130101; F41G 3/06 20130101 |
Class at
Publication: |
42/142 ;
434/27 |
International
Class: |
F41G 1/473 20060101
F41G001/473; G01C 1/00 20060101 G01C001/00 |
Claims
1. A method for determining hold over ballistic information, the
method comprising the steps of: determining a first range to a
target; determining an angle to the target; and determining a hold
over value based on the first range and the determined angle by
acquiring a projectile drop value and modifying the projectile drop
value utilizing the determined angle.
2. The method as set forth in claim 1, wherein the hold over value
is determined by multiplying the acquired projectile drop value by
the cosine of the acquired angle.
3. The method as set forth in claim 1, further including
determining a second range to the target by multiplying the first
range by the cosine of the acquired angle.
4. The method as set forth in claim 1, further including acquiring
configuration information and determining the hold over value based
upon the first range, the determined angle, and the configuration
information.
5. The method as set forth in claim 4, wherein the configuration
information includes one of a plurality of ballistic curves.
6. The method as set forth in claim 5, wherein each ballistic curve
corresponds to a ballistic curves of a projectile.
7. The method as set forth in claim 5, wherein each ballistic curve
corresponds to a ballistic curves of a firearm.
8. The method as set forth in claim 4, wherein the configuration
information includes a sight-in range.
9. A method for determining hold over ballistic information, the
method comprising the steps of: acquiring configuration
information; determining a first range to a target; determining an
angle to the target; and determining a hold overvalue based on the
first range, the determined angle and configuration information by
acquiring a first drop value and modifying the first drop value
utilizing the determined angle and a second drop value wherein the
configuration information corresponds to one of a plurality of
ballistic curves and a sight-in range.
10. The method as set forth in claim 9, wherein the hold over value
is determined by multiplying the acquired projectile drop value by
the cosine of the acquired angle.
11. The method as set forth in claim 9, further including
determining a second range to the target by multiplying the first
range by the cosine of the acquired angle.
13. The method as set forth in claim 9, wherein each ballistic
curve corresponds to a ballistic curves of a projectile.
14. The method as set forth in claim 9, wherein each ballistic
curve corresponds to a ballistic curves of a firearm.
15. The method as set forth in claim 9, wherein the second drop
value corresponds to the drop value of the ballistic curve at the
sight-in range.
Description
RELATED APPLICATION
[0001] The present application is a continuation patent application
and claims priority benefit, with regard to all common subject
matter, of earlier-filed U.S. patent application titled "HANDHELD
RANGEFINDER OPERABLE TO DETERMINE HOLD OVER BALLISTIC INFORMATION",
Ser. No. 11/314,593, filed Dec. 21, 2005. The identified
earlier-filed application is hereby incorporated by reference into
the present application.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to handheld rangefinders that
assist a user in compensating for deviations in projectile
trajectory. More particularly, the present invention relates to a
handheld rangefinder that utilizes a range sensor and a tilt sensor
to determine hold over ballistic information corresponding to
projectile trajectories.
[0004] 2. Description of the Related Art
[0005] Hunters and other firearm and bow users commonly utilize
handheld rangefinders to determine ranges to targets. Generally,
handheld rangefinders utilize lasers to acquire ranges for display
to a hunter. Utilizing the displayed ranges, the hunter makes
sighting corrections to facilitate accurate shooting.
Unfortunately, due to variations in elevation and slope, the ranges
determined by handheld rangefinders often are not accurate
representations of the horizontal distances projectiles must
travel.
[0006] For example, as shown in FIG. 1, a hunter positioned above
or below a target may be provided a range, 9 yards for instance,
that is different than the actual horizontal distance to the
target, 5 yards for instance, thereby resulting in inaccurate
shooting. Further, handheld rangefinders fail to determine hold
over ballistic information corresponding to the amount by which
hunters must vary their aim, thereby forcing hunters to manually
perform hold over calculations.
[0007] Devices operable to compensate for slope and elevation
utilizing lasers and inclinometers have been developed to alleviate
some of these problems. For example, U.S. patent application Ser.
Nos. 10/867,429 and 10/964,206, which are incorporated herein by
reference, disclose telescope sights and other optical devices
having a laser range sensor and an inclinometer. Unfortunately,
these devices have a limited field of vision, must be attached to a
firearm or bow, or are unable to provide hold over ballistic
information. Thus, hunters are unable to avail themselves of the
beneficial aspects of handheld rangefinders, such as increased
field of vision, maneuverability, and portability, while correcting
for range, slope, elevation, and rangefinder orientation utilizing
hold over ballistic information.
SUMMARY OF THE INVENTION
[0008] The present invention solves the above-described problems
and provides a distinct advance in the art of handheld
rangefinders. More particularly, the invention provides a handheld
rangefinder that utilizes a range sensor and a tilt sensor to
determine hold over ballistic information corresponding to
projectile trajectories. Such a configuration facilitates accurate
firearm and bow use by providing ranges and hold values without
requiring time-consuming and manual user calculations.
[0009] In one embodiment, the present invention provides a
rangefinder device for determining hold over ballistic information.
The device generally includes a range sensor operable to determine
a first range to a target, a tilt sensor operable to determine an
angle to the target relative to the device, and a computing
element, coupled with the range sensor and the tilt sensor,
operable to determine a hold over value based on the first range
and the determined angle.
[0010] In another embodiment, the rangefinder device includes a
laser range sensor operable to determine a first range to a target,
a tilt sensor operable to determine an angle to the target relative
to the device, a memory comprising a database of ranges and
corresponding projectile drop values, a computing element operable
to determine a hold over value based on the first range and the
determined angle by acquiring one of the projectile drop values
from the database and modifying the acquired projectile drop value
utilizing the determined angle, and a display operable to indicate
the first range and the hold over value.
[0011] In another embodiment, the rangefinder device includes a
laser range sensor operable to determine a first range to a target,
a tilt sensor including an inclinometer operable to determine an
angle to the target relative to the device, an input operable to
receive configuration information from a user, a memory comprising
a database of ranges and corresponding projectile drop values, a
computing element operable to determine a hold over value based on
the first range, the configuration information, and the determined
angle by acquiring one of the projectile drop values from the
database and modifying the acquired projectile drop value utilizing
the determined angle, a display operable to indicate the first
range and the hold over value, and a portable handheld housing.
[0012] In another embodiment, the present invention provides a
method for determining hold-over ballistic information. The method
generally comprises determining a first range to a target,
determining an angle to the target, and determining a hold over
value based on the first range and the determined angle by
acquiring a projectile drop value and modifying the projectile drop
value utilizing the determined angle.
[0013] Other aspects and advantages of the present invention will
be apparent from the following detailed description of the
preferred embodiments and the accompanying drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] A preferred embodiment of the present invention is described
in detail below with reference to the attached drawing figures,
wherein:
[0015] FIG. 1 is a schematic view showing various distances between
a hunter and a target;
[0016] FIG. 2 is a block diagram of a rangefinder device configured
in accordance with various preferred embodiments of the present
invention;
[0017] FIG. 3 is a rear perspective view of the rangefinder device
of FIG. 2;
[0018] FIG. 4 is a front perspective view of the rangefinder device
of FIGS. 2-3;
[0019] FIG. 5 is a diagram illustrating a first range to a target
and an associated projectile trajectory;
[0020] FIG. 6 is a diagram illustrating a second range and an
associated projectile trajectory to the target of FIG. 4 when the
target is elevated;
[0021] FIG. 7 is a diagram illustrating an angle to an elevated
target relative to the device;
[0022] FIG. 8 is a diagram illustrating various angles and
projectile trajectories relative to the device;
[0023] FIG. 9 is a chart illustrating a plurality of ballistic
curves; and
[0024] FIG. 10 a schematic view of a target observed while looking
through the device, a display indicating the first range, the
second range, and a hold over value.
[0025] The drawing figures do not limit the present invention to
the specific embodiments disclosed and described herein. The
drawings are not necessarily to scale, emphasis instead being
placed upon clearly illustrating the principles of the
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0026] The following detailed description of the invention
references the accompanying drawings that illustrate specific
embodiments in which the invention can be practiced. The
embodiments are intended to describe aspects of the invention in
sufficient detail to enable those skilled in the art to practice
the invention. Other embodiments can be utilized and changes can be
made without departing from the scope of the present invention. The
following detailed description is, therefore, not to be taken in a
limiting sense. The scope of the present invention is defined only
by the appended claims, along with the full scope of equivalents to
which such claims are entitled.
[0027] Turning now to the drawing figures, and particularly FIGS.
1-10, a rangefinder device 10 is shown constructed in accordance
with various preferred embodiments of the present invention. The
device 10 generally includes a range sensor 12 for determining a
first range to a target T, a tilt sensor 14 for determining an
angle to the target T, a computing element 16 coupled with the
range sensor 12 and the tilt sensor 14 for determining ballistic
information relating to the target T based on the first range and
the determined angle, a memory 18 for storing data such as
ballistic information and a computer program to control the
functionality of the device 10, and a portable handheld housing 20
for housing the range sensor 12, the tilt sensor 14, the computing
element 16, the memory 18, and other components described
below.
[0028] A computer program preferably controls input and operation
of the device 10. The computer program includes at least one code
segment stored in or on a computer-readable medium residing on or
accessible by the device 10 for instructing the range sensor 12,
tilt sensor 14, computing element 16, and any other related
components to operate in the manner described herein. The computer
program is preferably stored within the memory 18 and comprises an
ordered listing of executable instructions for implementing logical
functions in the device 10. However, the computer program may
comprise programs and methods for implementing functions in the
device 10 which are not an ordered listing, such as hard-wired
electronic components, programmable logic such as
field-programmable gate arrays (FPGAs), application specific
integrated circuits, conventional methods for controlling the
operation of electrical or other computing devices, etc.
[0029] Similarly, the computer program may be embodied in any
computer-readable medium for use by or in connection with an
instruction execution system, apparatus, or device, such as a
computer-based system, processor-containing system, or other system
that can fetch the instructions from the instruction execution
system, apparatus, or device, and execute the instructions. The
computer-readable medium may even be paper or another suitable
medium upon which the program is printed, as the program can be
electronically captured, via for instance, optical scanning of the
paper or other medium, then compiled, interpreted, or otherwise
processed in a suitable manner, if necessary, and then stored in a
computer memory.
[0030] The device 10 and computer program described herein are
merely examples of a device and a program that may be used to
implement the present invention and may be replaced with other
devices and programs without departing from the scope of the
present invention.
[0031] Referring to FIGS. 2-4, the range sensor 12 is operable to
determine the first range to the target T from the device 10. The
range sensor 12 may be any conventional sensor or device for
determining range. The first range preferably represents a length
of an imaginary line drawn between the device 10 and the target T,
as shown in FIG. 5, such as the number of feet, meters, yards,
miles, etc, directly between the device 10 and the target T. Thus,
the first range may correspond to a line of sight (LOS) between the
device 10 and the target T.
[0032] Preferably, the range sensor 12 is a laser range sensor
which determines the first range to the target by directing a laser
beam at the target T, detecting a reflection of the laser beam,
measuring the time required for the laser beam to reach the target
and return to the range sensor 12, and calculating the first range
of the target T from the range sensor 12 based on the measured
time. Thus, the range sensor 12 may include an emitter and a
detector to emit the laser beam and then detect the reflection of
the laser beam in a generally conventional manner.
[0033] The range sensor 12 is operable to determine a range to a
target even when objects, such as trees, people, vehicles, foliage,
etc, are positioned between the device and the target. As a result,
the range sensor 12 may determine the first range to the target T
in a variety of situations, including in outdoor situations where
various trees and/or other foliage may obstruct a direct view of
the target T.
[0034] The range sensor 12 may also include memory and processing
capabilities separate from the computing element 16 and memory 18,
such that the range sensor is operable to determine the range to
the target T without the assistance of additional components.
However, the range sensor 12 may rely upon the capabilities
provided by the computing element 16 and memory 18 to specifically
calculate and determine the first range.
[0035] The range sensor 12 may alternatively or additionally
include other range sensing components, such as conventional
optical, radio, sonar, or visual range sensing devices to determine
the first range in a substantially conventional manner.
[0036] The tilt sensor 14 is operable to determine the angle to the
target T from the device 10 relative to the horizontal. Thus, as
shown in FIGS. 5, 7, and 8, if the device 10 and the target T are
both positioned on a flat surface having no slope, the angle would
be zero. As shown in FIGS. 6 and 8, if the device 10 is positioned
below the target T the slope between the device 10 and the target T
is positive, the angle would be positive. Conversely, as shown in
FIG. 8, if the device 10 is positioned above the target T, such
that the slope between the device 10 and the target T is negative,
the angle would be negative.
[0037] It will be appreciated that the angle is not dependent upon
the specific contours of the ground, surface, or surfaces between
the device 10 and the target T, but rather the angle is preferably
determined based on the orientation of the device 10, as described
below.
[0038] The tilt sensor 14 preferably determines the angle by
sensing the orientation of the device 10 relative to the target T
and the horizontal. The orientation of the device 10 changes based
on the relative position of the target T to the device 10, as a
user of the device 10 aligns the device 10 with the target T and
views the target T through an eyepiece 22 and an opposed lens 24,
as described in more detail below. Thus, the orientation of the
device 10, specifically the tilt of the device 10 along its
longitudinal axis relative to the horizontal, indicates if the
target T is above or below the device 10.
[0039] For example, if the target T is above the device 10, the
user of the device 10 would tilt the device 10 such that a distal
end 26 of the device 10 would be raised relative to a proximate end
28 of the device 10 and the horizontal. Similarly, if the target T
is below the device 10, the user of the device 10 would tilt the
device 10 such that the distal end 26 of the device 10 would be
lowered relative to the proximate end 28 of the device and the
horizontal. T
[0040] The tilt sensor 14 preferably determines the angle of the
target to the device 10 based on the amount of tilt, that is the
amount the proximate end 28 is raised or lowered relative to the
distal end 26, as described below. The tilt sensor 14 may determine
the tilt of the device, and thus the angle, through various
orientation determining elements. For instance, the tilt sensor 14
may utilize one or more single-axis or multiple-axis magnetic tilt
sensors to detect the strength of a magnetic field around the
device 10 or tilt sensor 14 and then determine the tilt of the
device 10 and the angle accordingly. The tilt sensor 14 may
determine the tilt of the device using other or additional
conventional orientation determine elements, including mechanical,
chemical, gyroscopic, and/or electronic elements, such as a
resistive potentiometer.
[0041] Preferably, the tilt sensor 14 is an electronic
inclinometer, such as a clinometer, operable to determine both the
incline and decline of the device 10 such that the angle may be
determined based on the amount of incline or decline. Thus, as the
device 10 is aligned with the target T by the user, and the device
10 is tilted such that its proximate end 28 is higher or lower than
its distal end 26, the tilt sensor 14 will detect the amount of
tilt which is indicative of the angle.
[0042] The computing element 16 is coupled with the range sensor 12
and the tilt sensor 14 to determine ballistic information relating
to the target T, including hold over ballistic information, as is
discussed in more detail below. The computing element 16 may be a
microprocessor, microcontroller, or other electrical element or
combination of elements, such as a single integrated circuit housed
in a single package, multiple integrated circuits housed in single
or multiple packages, or any other combination. Similarly, the
computing element 16 may be any element which is operable to
determine hold over ballistic information from the first range and
angle as described below. Thus, the computing element 16 is not
limited to conventional microprocessor or microcontroller elements
and may include any element which is operable to perform the
functions described below.
[0043] The memory 18 is coupled with the computing element 16 and
is operable to store the computer program and a database including
ranges, projectile drop values, and configuration information, as
is discussed in detail below. The memory 18 may be, for example, an
electronic, magnetic, optical, electro-magnetic, infrared, or
semi-conductor system, apparatus, device, or propagation medium.
More specific, although not inclusive, examples of the memory 18
include the following: volatile and non-volatile memory, an
electrical connection having one or more wires, a portable computer
diskette, a random access memory (RAM), a read-only memory (ROM),
an erasable, programmable, read-only memory (EPROM or Flash
memory), an optical fiber, a portable compact disc (CD), or a
digital video disc (DVD). However, the memory 18 may be of any form
operable to store the necessary computer program and data.
[0044] The memory 18 may be integral with the computing element 16,
such that the memory 18 and the computing element 16 are stored
within or on the same wafer, die, or package, or the memory 18 may
be discrete with the computing element 16 such that the memory 18
and the computing element 16 are stored on different wafers, dies,
or packages. Additionally, the memory 18 may be coupled with other
components, such as the range sensor 12 and tilt sensor 14, to
enable the other components to utilize the functionality provided
by the memory 18. The memory 18 may also be accessible by other
external devices, such as conventional computing devices, to enable
data stored within the memory, such as the database or the computer
program, to be easily accessed or modified by conventional
computing devices.
[0045] The device 10 also preferably includes a display 30 to
indicate relevant information such as the target T, the first
range, the angle, and ballistic information such as hold over
information, a reticle or other alignment element, etc. The display
30 may be a conventional electronic display, such as a LED, TFT, or
LCD display. Preferably, the display 30 is viewed by looking
through the eyepiece 22 such that the user may align the target T
and simultaneously view relevant information, as shown in FIG.
10.
[0046] For instance, the user may look through the eyepiece 22,
align the target T, view the target T, and generally simultaneously
view the display 30 to determine the first range, the angle
.theta., hold over value, and/or other relevant information. The
generally simultaneous viewing of the target T and the relevant
information enables the user to quickly and easily determine ranges
and ballistic information corresponding to various targets by
moving the device 10 in an appropriate direction and dynamically
viewing the change in the relevant information on the display
30.
[0047] The portable handheld housing 20 houses the range sensor 12,
tilt sensor 14, computing element 16, and/or other desired elements
such as the display 30, one or more inputs 32, eyepiece 22, lens
24, laser emitter, laser detector, etc. The handheld housing 20
enables the device 10 be easily and safely transported and
maneuvered for convenient use in a variety of locations.
[0048] For example, the portable handheld housing 20 may be easily
transported in a backpack for use in the field. Additionally, the
location of the components on or within the housing 20, such as the
position of the eyepiece 22 on the proximate end 28 of the device
10, the position of the lens 24 on the distal end 26 of the device,
and the location of the inputs 32, enables the device 10 to be
easily and quickly operated by the user with one hand without a
great expenditure of time or effort.
[0049] The inputs 32 are coupled with the computing element 16 to
enable users, third parties, or other devices to share information
with the device 10. The inputs 32 is generally associated with the
housing 20, such as by physical connection through wires, etc, or
wirelessly utilizing conventional wireless protocols. Thus, the
inputs 32 need not be physically coupled with the housing 20.
However, the inputs 32 are preferably positioned on the housing 20
to enable the user to simultaneously view the display 30 through
the eyepiece 22 and function the inputs 32.
[0050] The inputs 32 preferably comprise one or more functionable
inputs such as buttons, switches, scroll wheels, etc, a touch
screen associated with the display 30, voice recognition elements,
pointing devices such as mice, touchpads, trackballs, styluses,
combinations thereof, etc. Further, the inputs 32 may comprise
wired or wireless data transfer elements such as removable memory
including the memory 18, network connections, data transceivers,
etc, to enable the user and other devices or parties to remotely
interface with the device 10.
[0051] In operation, the user aligns the device 10 with the target
T and views the target T on the display 30. The device 10 may
provide generally conventional optical functionality, such as
magnification or other optical modification, by utilizing the lens
24 and/or the computing element 16. Preferably, the device 10
provides an increased field of vision as compared to conventional
riflescopes to facilitate conventional rangefinding
functionality.
[0052] Further, the user may function the inputs 32 to control the
operation of the device 10. For example, the user may activate the
device 10, provide configuration information as discussed below,
and/or determine a first range, a second range, angle, and
ballistic information by functioning one or more of the inputs
32.
[0053] For instance, the user may align the target T by centering
the reticle over the target T and functioning at least one of the
inputs 32 to cause the range sensor 12 to determine the first
range. Alternatively, the range sensor 12 may dynamically determine
the first range for all aligned objects such that the user is not
required to function the inputs 32 to determine the first range.
Similarly, the tilt sensor 14 may dynamically determine the angle
for all aligned objects or the tilt sensor may determine the angle
when the user functions at least one of the inputs 32. Thus, the
ranges, angle, and ballistic information discussed below may be
dynamically displayed to the user.
[0054] In various embodiments, the device 10 enables the user to
provide configuration information to facilitate determination of
ballistic information, including hold over information, by the
computing element 16. The configuration information includes mode
information to enable the user to select between various projectile
modes, such as bowhunting and firearm modes discussed below in more
detail, to enable the device 10 to provide information
corresponding to the selected mode, as is described below. Further,
the configuration information may include projectile information,
such as a bullet size, caliber, grain, shape, type, etc and firearm
caliber, size, type, sight-in distance, etc.
[0055] Preferably, the provided configuration information
corresponds to one of a plurality of ballistic curves. For example,
the user may select one curve, or provide an indication relating to
one curve, instead of entering detailed and complex ballistic
information such as bullet shape, grain, caliber, etc. As shown in
FIG. 9, five sample curves, C1-C5, are provided each corresponding
to a particular ballistic profile. For instance, C4 may correspond
to a pistol profile, C3 may correspond to a small-caliber rifle
profile, C2 may correspond to a rifle profile, C5 may correspond to
a medium-power rifle profile, C1 may correspond to a high-power
rifle profile, etc. As should be appreciated, innumerable
combinations of ballistic curves may exist each corresponding to
any ballistic profile. Various ballistic curves and associated
projectile drops are disclosed in U.S. Pat. No. 3,990,155, which is
incorporated herein by reference.
[0056] The user may provide the configuration information to the
device 10 by functioning the inputs 32. For example, the user may
depress one or more of the inputs 32 to provide configuration
information and/or the user may provide electronic data utilizing
the inputs 32 through a data connection, etc. Additionally, the
display 30 may present prompts, indication elements, menus,
selectable lists, etc, to help the user in providing the
configuration information.
[0057] Further, the memory 18 may include information corresponding
to configuration information to enable the user-provided
configuration information to be stored by the memory 18. Also, the
memory 18 may include a database of configuration information, such
as the plurality of ballistic curves or data corresponding to the
ballistic curves, to enable the user to select configuration
information from the data stored by the memory 18. For example, the
display 30 may provide a listing of stored configuration
information for selection by the user.
[0058] In embodiments where the memory 18 comprises non-volatile
memory, the configuration information may be permanently stored by
the user such that the user need not repeatedly provide the
information each time the device 10 is used. However, due to the
ease in which one of the plurality of ballistic curves may be
selected, utilization of non-volatile memory is not necessary in
all embodiments.
[0059] In various embodiments, the device 10 is operable to
determine a second range to the target T and display an indication
of the second range to the user. The computing element 16 is
coupled with the range sensor 12 and the tilt sensor 14 to
determine the second range to the target T based on the first range
and the determined angle. The second range may be determined
statically such that the second range is determined only at desired
intervals or upon input by the user. Conversely, the second range
may be dynamically determined such that the second range may be
continuously updated as new first ranges or angles or provided.
Thus, the second range may be accurately determined for moving
targets, such as a hunted animal, as the change in the targets
position is accounted for by the dynamic calculations.
[0060] The computing element 16 determines the second range to the
target T by adjusting the first range based upon the angle.
Preferably, the computing element 16 determines the second range by
multiplying the first range by the sine or cosine of the angle. For
instance, when the hunter is positioned above the target, the first
range is multiplied by the sine of the angle to determine the
second range. When the hunter is positioned below the target, the
first range is multiplied by the cosine of the angle to determine
the second range.
[0061] Thus, the second range preferably represents a horizontal
distance the projectile must travel such that the estimated
trajectory of the projectile generally intersects with the target
T. In contrast, the first range represents the length of an
imaginary line, such as a line of sight, between the device 10 and
the target T, which is a substantially straight line, as described
above. As is known in the art, projectiles which are not
self-propelled, such as bullets, golf balls, footballs, arrows,
etc, move through air according to a generally parabolic
(ballistic) curve due primarily to the effects of gravity and air
drag. In situations where the angle is zero, the parabolic movement
of the projectile does not substantially affect the range
calculation, such that the first range and the second range may be
substantially equal.
[0062] As shown in FIG. 6, in situations where the angle is
non-zero, such as when the target T is positioned above or below
the device 10, the parabolic movement of the projectile affects the
range calculation, such that the projectile may have to travel a
longer or shorter distance to reach the target T. Thus, the second
range provides an accurate representation to the user of the
flat-ground distance the projectile must travel to intersect the
target T.
[0063] For example, referring to FIG. 1, the device 10 would
determine the first range to be 9 yards, as the first range
generally corresponds to a line of sight between the device 10 and
the target T. The device 10 would determine the second range,
utilizing the angle acquired by the tilt sensor 14, to be 5 yards,
representing the horizontal distance the projectile must travel to
strike the target T.
[0064] Although the second range may be dynamically presented by
the display 30 without requiring user input, the second range is
preferably displayed only when the device 10 is in bowhunting mode
as indicated by the user-provided information. Such a configuration
may be desirable as a true horizontal distance to a target, as
indicated by the second range, may be of little use to firearms
that have compact ballistic curves due to the high velocity at
which fired projectiles travel. In contrast, bow-fired projectiles
are fired with controllable force by the user at generally short
ranges such that the second range greatly facilitates targeting, as
is shown in FIG. 1.
[0065] The device 10 is further operable to determine ballistic
information including a hold over value corresponding to an amount
of hold over. As is known in the art, hold over refers to the
amount by which the user must aim high, or above the target, to
compensate for the effects of trajectory, projectile drop, and
angle. Thus, the hold over value determined by the device 10
provides an indication of how much, or to what degree, the user
must aim high in relation to the target to accurately fire a
projectile.
[0066] FIG. 8 illustrates three exemplary projectile trajectories
and corresponding bullet drops. For each angle, positive, zero, and
negative, three paths are illustrated: path 1 corresponds to a line
of departure, which represents an a projectile trajectory
comprising a hypothetical infinite straight line; path 2
corresponds to a parabolic (ballistic) trajectory resulting from
the effects of gravity and drag on path 1; and path 3 corresponds
to a light of sight to the target. As can be seen, the difference
between path 1 and path 2 corresponds to projectile drop, which
varies as the range and angle changes.
[0067] As is known in the art and as shown in FIG. 8, firing a
projectile at uphill or downhill angles affects the trajectory of
the projectile by causing the projectile to impact high relative to
the projectile path for level fire. The deviations in trajectory
grow larger as range and angle increase. Further, projectiles
impact slightly higher when fired downhill than uphill at the same
angle due to the varying effects of gravity on uphill and downhill
trajectories. Thus, to correct for projectile drop, it is generally
necessary to aim above a target.
[0068] Additionally, as will be appreciated by those skilled in the
art, the amount of hold over is dependent on the range at which a
firearm is sighted in. For instance, firearms are typically sighted
in at 100 yards, to build-in appropriate hold over for projectile
drop, such that a user need not hold over when firing at targets at
100 yards, but would need to hold over for targets substantially
over 100 yards. The device 10 preferably utilizes a default sight
in distance of 100 yards, which may be stored in the memory 18.
However, the device 10 may utilize a user-provided sight in
distance, as discussed above, to determine the hold over value.
[0069] The device 10 may determine the hold over value utilizing
various methods. Preferably, the computing element 16 determines
the hold over value utilizing the first range and the determined
angle by acquiring a projectile drop value corresponding to the
first range and modifying the projectile drop value utilizing the
determined angle. The projectile drop value corresponds to the
amount of vertical projectile drop at a particular range and at
zero angle. Similarly, the computing element 16 may acquire a
plurality of projectile drop values and modify the plurality of
projectile drop values utilizing the acquired angle to determine
hold over values accordingly.
[0070] The computing element 16 may acquire the projectile drop
value from the memory 18. For instance, as described above, the
memory 18 may include a database of ballistic information,
including a listing, table, chart, etc, of projectile drop values
corresponding to various ranges and configuration information. For
instance, the database may include data corresponding to the chart
of FIG. 9 to enable the retrieval of a projectile drop value, in
minutes of angle (MOA), inches, yards, centimeters, reticle
positions, etc, based upon the first range.
[0071] Preferably, the projectile drop value is retrieved utilizing
both the first range and the configuration information. For
instance, as is shown in FIG. 9, the projectile drop value may be
dependent upon the particular projectile or firearm utilized, such
that retrieving a projectile drop value corresponding to a utilized
projectile facilitates accurate shooting. Thus, in embodiments
where the user selects one of the plurality of ballistic curves,
the projectile drop value is preferably retrieved utilizing the
selected ballistic curve and the first range.
[0072] The computing element 16 may also or additionally acquire
the projectile drop value utilizing a look-up table or other
database element. For example, the database may include an ordered
listing, table, and/or relational listing of ranges, configuration
information, and projectile drop values, such that the projectile
drop value may be acquired by providing the range and configuration
information, such as projectile curve, type, size, etc. Such data
corresponding to projectile drop values, ranges, and other
ballistic information is commonly available through numerous
sources such as bullet manufacturers, firearm manufacturers,
internet databases, textbooks, etc, and may be stored within the
memory 18 for retrieval by the computing element 16 and/or to help
the user in providing configuration information.
[0073] Further, as will be appreciated by those skilled in the art,
the projectile drop value may be dependent on the range at which
the firearm or bow is sighted in. For instance, the chart of FIG. 9
indicates a projectile drop value of zero at 100 yards as a firearm
sighted-in at 100 yards and thus on a level surface would
experience no additional drop for which compensation is required by
the user.
[0074] The computing element 16 may utilize a default sight-in
range of 100 yards and retrieve projectile drop values accordingly
and/or the computing element 16 may utilizing a user-provided
sight-in range and retrieve projectile drop values accordingly or
modify a retrieved projectile drop value utilizing conventional
algorithms to reflect variations in sight-in range.
[0075] To compensate for angled projectile trajectories in
determining the hold over value, the computing element 16 is
operable to utilize the angle determined by the tilt sensor 14 to
modify the acquired projectile drop value. As explained above and
shown in FIG. 8, the projectile drop value varies according to
angle. The amount of variance may be express utilizing a cosine of
the acquired angle.
[0076] Specifically, the hold over value may be determined by the
computing element 16 by multiplying the projectile drop value
corresponding to the first range by the cosine of the acquired
angle. The hold over value, configuration information, projectile
drop values, and other data may be provided and/or displayed
utilizing various units. For example, the hold over value and
projectile drop values may correspond to minutes of angle, inches,
centimeters, reticle positions, combinations thereof, etc. As shown
in FIG. 10, the hold over value may be displayed by the display 30
as both a numerical value in inches, 24 inches for example, or as
one or more reticles, such as a first reticle and a second
reticle.
[0077] For instance, the first reticle may be a fixed reticle that
corresponds to the sight-in range while the second reticle may be a
dynamically-displayed reticle that reflects changes to the first
reticle based upon the determined hold over value. The hold over
value may also refer to one or more reticles on the user's
riflescope, such as the number of dots on the a reticle that the
user must aim high.
[0078] Further, the information presented on the display 30 may be
dependent upon the first range to the target T. Specifically, in
situations where the first range is less than 100 yards, the first
and second ranges may be displayed, but not the hold over value or
angle, as the second range, representing true horizontal distance,
is often more important for short-range accuracy than hold over
information. For instance, when the device 10 is in bowhunting mode
the display 30 presents the first and second ranges but not the
hold over value.
[0079] In contrast, where the second range is greater than 100
yards, the first range, the hold over value, and/or the angle may
be displayed, but not the second range, as the hold over value is
often more important for long-range accuracy than true horizontal
distance. For instance, when the device 10 is in firearms mode, the
first range and the hold over value are preferably shown but not
the second range.
[0080] Thus, the provided bowhunting mode is preferably limited to
ranges less than 100 yards and does not present an indication of
the hold over value while the provided firearms mode is not limited
to any particular ranges and presents an indication of the first
range and the hold over value. As should be appreciated by those
skilled in the art, the firearms mode may additionally be operable
to calculate a hold under value utilizing the first range and the
determined angle.
[0081] Although the invention has been described with reference to
the preferred embodiments illustrated in the attached drawings, it
is noted that equivalents may be employed and substitutions made
herein without departing from the scope of the invention as recited
in the claims.
[0082] Having thus described the preferred embodiment of the
invention, what is claimed as new and desired to be protected by
Letters Patent includes the following:
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