Abstract:
A variable limits setting dive computer for SCUBA divers which permits individual diver selectable time values for different diver physiology for commencing the ascent on the dive time remaining display, with diver controlled overrides, together with a tissue loading bar graph with diver pre-determined and variable visual and audible alarms actuated by the selected setting on said bar graph.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a novel method and apparatus for underwater data sensing and processing for SCUBA divers. More particularly, it relates to a portable underwater computer having data sensors, a software program and processor, and a specialized display and control. The computer provides integrated visual information to a diver numerically and graphically and permits the diver to set variable limits on his dive parameters to provide visual and aural warnings with respect thereto.  
           [0003]    Still more particularly, the present invention provides a variable limits setting dive computer for SCUBA divers which permits individual diver selectable time values, for different diver physiology, for commencing the ascent on the dive time remaining display, with diver controlled overrides, together with a tissue loading bar graph with diver pre-determined and variable visual and audible alarms with respect to the commencement of ascent from the dive actuated by the selected setting on said bar graph.  
           [0004]    2. Description of the Prior Art  
           [0005]    The use of dive computers in one design or another for the purpose of assisting SCUBA divers is well known in the prior art. However, despite the numerous designs, structures, and forms of apparatus which have been developed and disclosed by the prior art, specifically for the accomplishment of the objectives, purposes, and requirements of SCUBA divers, the various devices, machines, and methods which have been heretofore devised and utilized to accomplish this goal consist basically of obvious configurations, combinations, and arrangements of well known apparatus. This will become apparent from the following consideration of the closest known and relevant prior art.  
           [0006]    The use of dive computers to help SCUBA divers to avoid “decompression sickness” (DCS) is well developed in the art and is comprehensibly disclosed in the Description of the Prior Art section of U.S. Pat. No. 4,882,678 for a Data Sensing and Processing Device for SCUBA Divers, issued Nov. 21, 1989, to Hollis, et al. The disclosure sets forth the relevanthistory of the development of the U.S. Navy Dive Tables to permit a diver to avoid DCS and of the computers utilized to implement the use of the tables.  
           [0007]    The &#39;678 patent discloses a dive computer which utilizes original mathematical algorithms, assumptions, and calculations which modify the conservative U.S. Navy Dive Tables to provide longer underwater dive times for sport divers. The modified tables and algorithms disclosed in the patent are designed to accommodate variable dive profiles as compared with Navy divers who work at a constant depth. The &#39;678 patent is the first to provide a dive computer which is designed to specifically avoid a decompression condition by giving the diver the information needed to plan a dive, maintain a safe air reserve, and dive within the no decompression limits accepted by the U.S. Navy. However, the computer includes an emergency decompression scale/guide based on the Navy tables for divers who get into trouble by descending into the decompression zone (DZ) as long as they do not exceed 10 minutes therein.  
           [0008]    An improvement in the prior art of SCUBA dive computers as described in the &#39;678 patent is the Ascent Rate Meter for SCUBA Divers disclosed in U.S. Pat. No. 5,156,055, issued Oct. 20, 1992, to Hollis, et al. In order for a diver to control his or her ascent from depth during a decompression dive into the DZ, they need to know the ascent rate. The purpose of the &#39;055 invention is to establish a means for accurately calculating a divers ascent rate in order that this information can be added to the display of the dive computers that are used for sport and commercial SCUBA decompression diving.  
           [0009]    A somewhat parallel development in dive computers for SCUBA divers is U.S. Pat. No. 5,457,284 for an Interactive Dive Computer, issued Oct. 10, 1995, to Ferguson. It is described by the inventor, in the abstract of the patent, as “[A]n interactive apparatus for use by a SCUBA diver to provide for diver control of a specified dive-related parameter. The diver enters into the apparatus the desired parameter value, such as air reserve available at the completion of the dive, and the apparatus, based on the desired parameter and current dive conditions, determines the length of time the diver may remain at the current depth and still safely ascend to the surface with the desired air reserve. In the preferred embodiment of the invention, the apparatus also includes audible and visual alarms to alert the diver to the expiration of the determined length of safe dive time.” 
           [0010]    Specifically, it is stated in the specification of the &#39;284 patent that the reason for the invention is because “[T]here is a need . . . for an instrument that determines a safe diving or air reserve period based on both current dive conditions and the diver&#39;s personal safety margin preferences, as well as the diver&#39;s particular physical profile.” As a result, it is stated that: “[I]t is a main object of the invention to provide a dive computer designed to guide a diver to the surface with a diver specified air reserve remaining in a compressed air supply at the completion of the dive.” The device is designed to allow a diver to accommodate his or her safety margin to their specific physiology and personal preferences based on air time remaining (ATR).  
           [0011]    The present invention is for the same general purpose, which is to provide SCUBA divers with a computer of which accommodates different diver physiology and allows him or her to establish diver selected safety margins, but it achieves the results in a different way, with different apparatus, and for critically different diving parameters. The substantial difference between the computers is that the &#39;284 design is for measuring ATR while the present invention is based on computing tissue onloading which incorporates decompression ascent calculations and allows a diver to avoid the more severe physical punishment of a dive to the limits.  
           [0012]    These two types of diving time measurements are mutually exclusive for dive computer operation and even though they necessarily overlap when a diver descends into the DZ. Air time remaining is not a determining factor unless the diver remains above the DZ. The &#39;284 patent bases its display solely on air time remaining which is based on pressure in the air tanks, depth, and time, measured against a rigid nitrogen onloading scale, although it is not described, and provides a safety factor by permitting a preset which triggers an alarm based on a selected air time remaining safety margin. The present invention provides information for variable preset safety margins for decompression diving into the DZ based on nitrogen onloading whereby a less physically demanding dive profile can be selected than is permitted by the program of the &#39;284 patent.  
           [0013]    The Ferguson &#39;284 patent permits a diver to select a safety margin in the dive time remaining (DTR) display in the computer by providing for an alarm based on an air pressure remaining in the tank. The algorithm utilized by the 284 patent for DZ diving is fixed and unalterable by the diver selecting his or her ATR safety value. The diver must follow the set rigors of the internal program of the computer and follow the decompression (DECO) profile thereof. That can often be a harsh regimen for older divers.  
           [0014]    The present invention is concerned with safety margins set by a diver but measured by different parameters in a different way with different apparatus. The &#39;284 diver is concerned with arriving back at the surface with a pre-selected air reserve, but, as emphasized earlier, air time remaining is not the determining factor for a diver unless he or she remains above the decompression zone (DZ). A diver is limited in the DZ by depth and time caused by tissue onloading, basically of nitrogen, which causes DCS. In order to ascend from the DZ, a diver must make decompression (DECO) stops at computed levels during the ascent. The deeper and longer a diver remains in the DZ, the longer and more numerous the required DECO stops. The &#39;284 device gives the diver no warning of how the severity of the DECO regimen for a particular dive is progressing. The present invention indicates that exact factor and permits a diver to restrict or limit before hand the severity of the DECO regimen.  
           [0015]    The present invention is based on a more accurate indicator of dive time remaining based on tissue nitrogen loading from the Navy Dive Tables with a multiple of alarms and with a selectable safety margin for decompression diving. The present invention allows for diving into the DZ and bases DTR on a modified set of Navy Dive Tables which in turn can be further modified to conform with a diver&#39;s selected personal safety margins. As a diver grows older, he or she becomes less capable of enduring the effects of tissue on loading and DCS, so they prefer to set larger margins of safety than are provided by computerized calculations of safety based on the Navy Dive Tables and as modified by various computer programs. In the present invention, the DZ factor is calculated by the computer and the diver can select the safety margin based on the degree of tissue nitrogen onloading.  
           [0016]    The variable setting dive computer contemplated according to the present invention departs substantially from the conventional concepts and designs taught by the prior art, and in doing so, provides an apparatus primarily developed for the purpose of providing a SCUBA diver with the capability of selecting variable pre-sets with respect his or her personal physiology during a DZ dive as described above, but it accomplishes the result in a different and improved manner, and with new apparatus, for producing safer diving conditions more accurately, faster, and with more versatility.  
         SUMMARY OF THE INVENTION  
         [0017]    In view of the foregoing known, described, and obvious disadvantages inherent in the known types of dive computers for SCUBA divers presently existing in the prior art, the present invention provides a new method of diver condition monitoring for DZ diving, and a new apparatus and construction for a dive computer wherein the same can be utilized by divers to pre-select personal choice variable limits for tissue onloading conditions in the DZ to avoid DCS.  
           [0018]    The general purpose of the present invention, which will be described hereafter in greater detail, is to provide a new and improved dive computer apparatus and method which has many of the vantages of the prior art of dive computers mentioned and described above and many novel features and advantages that result in a new variable limits dive computer which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art of dive computers heretofore known, either alone or in any combination thereof.  
           [0019]    The present invention is a variable limits setting dive computer for a SCUBA diver which permits establishing variable diver selected tissue loading limit values for a dive. The invention comprises at least a minimum of data sensors for said computer including at least water depth and elapsed time. A computer means is provided with a software algorithm based on the Navy Dive Tables for integrating the output from the sensors and producing a computer output in response thereto. A data display is provided including a tissue loading bar graph which is actuated by the output of the computer and indicates when DECO status has been reached. A selection means is provided which is operable by a diver to select a value on the tissue loading bar graph for triggering at least one alarm when the selected value is reached during a dive by the output from the computer activating the TLBG in response to having the processor integrate the output from the sensors.  
           [0020]    The more important features of the invention have been broadly outlined in the preceding summary of the invention in order that the detailed description thereof which follows may be better understood and in order that the present contribution to an improvement in the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.  
           [0021]    With respect to the claims hereof, and before describing at least one preferred embodiment of the invention in detail, it is to be understood that the invention is not to be limited in its application to the details of construction and to the arrangements of the components which are set forth in the following description or illustrated in the accompanying drawings. The invention is capable of being created in other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed here are for the purpose of description and should not be regarded as limiting.  
           [0022]    As such, those skilled in the art in which the invention is based will appreciate that the conception upon which this disclosure is predicated may readily be utilized as a basis for the designing of other forms, structures, apparatus, systems, and methods for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions and methods in so far as they do not depart from the spirit and scope of the present invention.  
           [0023]    Further, the purpose of the appended abstract is to enable the United States Patent and Trademark Office, and the public generally, and especially scientists, engineers and practitioners of the art who are not familiar with the patent and legal terms or phraseology, to determine quickly from cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the specification, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.  
         OBJECTS OF THE INVENTION  
         [0024]    It is therefore an important object of the present invention to provide a variable limits setting dive computer in which the nitrogen tissue loading parameter limit is diver selectable.  
           [0025]    It is another object of the present invention to provide a dive computer with a nitrogen tissue loading bar graph in which a selectable value thereon automatically activates alarms when it is reached by the output of the computer.  
           [0026]    It is a further object of the present invention to provide a dive computer which compensates for dive profiles which vary during a dive into and out of the DZ to provide a visual representation of the status of the diver&#39;s tissue loading Other objects and advantages of the present invention will become apparent when the method and apparatus of the present invention are considered in conjunction with the accompanying drawings. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is an illustration of a dive computer data display as utilized with and employing the present invention showing the tissue loading bar graph beginning activation in the green zone;  
         [0028]    [0028]FIG. 2 is an illustration of the data display showing partial actuation still in the green zone; and  
         [0029]    [0029]FIG. 3 is an illustration of the data display showing full actuation into DECO status. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    Reference is made to the drawings for a description of the preferred embodiment of the variable setting dive computer of the present invention wherein like reference numbers represent like elements on corresponding views. FIGS.  1 - 3  show the data display  11  on the computer control console which is actuated by the output of the internal computer and which employs the unique tissue loading bar graph  13  of the present invention.  
         [0031]    The three views of the display console are shown in various stages of actuation with respect to the tissue loading bar graph (TLBG) of the present invention. The LCD display face is surrounded by the cylindrical end of the computer case  15  which has color indicia imprinted thereon for supplementing the display indicia. Green colored edging  17  indicates a safe bar graph indication. A yellow colored edging  19  indicates a warning zone bar graph indication, and red colored edging  21  indicates a danger zone bar graph indication.  
         [0032]    A variable colored LCD display could be utilized, but it is considered too expensive for practical utilization in the present invention at the present time. However, such embodiments of the invention are covered by the claims hereof in anticipation of the time when they can be practically implemented.  
         [0033]    The dive computer of the present invention is very compact and can be worn on a divers forearm like a wrist watch which is a convenient viewing orientation for underwater information retrieval because of most persons normal experience in checking time on a wrist watch. The display  11  is generally circular and the computer considerably larger and heavier than a watch, and despite the larger size and weight, because water displacement lessens the effect of the weight of the computer on the divers wrist underwater, the added visibility of the larger visual display compensates for the minor disadvantages of the large size. The critical information is displayed in large numbers which can be read at an extended arms length.  
         [0034]    The variable setting dive computer has an interactive control console consisting of two control buttons  23 ,  25  which allow the user to select display options and access specific information. They are also used to enter settings, activate the backlight, and acknowledge the audible alarms. The front button is referred to as “advance” and the side button as “select.” 
         [0035]    There are several bar graphs imposed on the display including: a tissue loading bar graph (TLBG)  13 , oxygen accumulation bar graph (02BG)  27 , a variable ascent rate meter (VARI)  29 . There are also several alpha/numeric and other visual displays including: a depth display  31 , time and date displays  33 , temperature display, LED warning light  37 , backlight, power supply (battery status) indicator, F02 mode, and audible alarms.  
         [0036]    The tissue loading bar graph (TLBG)  13  represents tissue loading of nitrogen, showing the diver&#39;s relative no decompression or decompression status. As depth and elapsed dive time increase, segments are added to the graph, and as the diver ascends to shallower depths, the bar graph will begin to recede, indicating that additional no decompression time is allowed for multilevel diving.  
         [0037]    The TLBG  13  is controlled by a custom algorithm derived from the Navy Dive Tables which monitors  12  different nitrogen components simultaneously and displays the one that is in control of the particular dive. An example of such an algorithm is disclosed in the Hollis &#39;678 patent. Other algorithms which monitor tissue loading can be utilized with the present invention. The TLBG is divided into a green “no decompression” (normal) zone  17 , a yellow caution zone (also no decompression)  19 , and a red decompression (danger) zone  21 . While a diver cannot be given a guarantee against the occurrence of DCS by using the graph, he or she may choose their own personal zone of caution based upon age, physique, excessive weight, and physical condition to reduce the statistical risk.  
         [0038]    In addition to the TLBG graph  13 , the oxygen accumulation bar graph (02BG)  27  represents oxygen loading showing the maximum of either per dive accumulated oxygen or  24 -hour period accumulated oxygen.  
         [0039]    The variable ascent rate indicator (VARI)  29  provides a visual representation of ascent speed (i.e., an ascent speedometer). Green color represents a normal rate, yellow a caution rate, and red indicates too fast.  
         [0040]    The alpha/numeric displays include a depth display  31  showing the depth during the dive. By pressing the advance button  23 , the maximum depth reached the during a dive will be displayed in the center/left portion of the display. During a decompression dive, the required “ceiling stop depth” is displayed in the center the screen.  
         [0041]    The time displays are shown in the hour and minute format. The colon that separates the hours and minutes blinks once per second when the display is indicating real-time (e.g., elapsed dive time), and is solid (non-blinking) when times are calculated projections (e.g., time to fly). The main time display is located in the lower portion of the display and a second time display is located in the center/right. Both displays are identified by a clock icon. Date is displayed in the center left portion of the screen only to identify dive data when it is viewed in the log mode.  
         [0042]    Ambient temperature is displayed in the center/left portion of the screen while the computer is in the surface mode and log mode and can be viewed as part of an alternate display when the advance button is pressed while in a dive mode.  
         [0043]    A red LED warning light  37  and speaker icon are synchronized with the audible alarm and will illuminate the display when the alarm emits a tone. They will turn off when the alarm is acknowledged or set to off (a user setting). When warning situations activate the alarm, the unit will emit a continuous tone for 30 seconds, or until the situation is corrected, or it is acknowledged by pressing the advance button for two seconds. The audible and LED alarms can also be set for activation under other conditions.  
         [0044]    The backlight can be activated by pressing the side button  25 . The battery power supply includes an indicator in the lower left corner of the display which is displayed when power is sufficient for normal unit operation and is not displayed during dive modes.  
         [0045]    The dive computer will operate as an air computer without displaying information associated with oxygen calculations (F02 mode) unless it is set for a percentage of oxygen other than air in which case it will operate as a gas calculator.  
         [0046]    The variable setting dive computer of the present invention is designed for SCUBA divers and permits the establishment of variable diver selected tissue loading limit values for a dive. In order for a dive computer to utilize the method of the present invention, it must include apparatus which is comprised of data sensors for the computer which include at least a water depth sensor (ambient hydrostatic pressure) and an elapsed time timer. In order to perform the full function of a state-of-the-art dive computer, such as described in the Hollis 678 patent, the device also requires air tank high and low pressure transducers, breathing rate sensor, ascent rate sensor (such as described in the Hollis et al. &#39;055 patent), and temperature sensor.  
         [0047]    The tissue loading bar graph (TLBG)  13  of the present invention is a visual display in the form of a progressively changing pictorial representation. There are numerous forms for a bar graph representation such as: a series of aligned blocks which change color or shape; an elongating bar either straight or curved: a series of objects which progressively appear and disappear, or are progressively illuminated or interconnected and the reverse; and any combination of these representations and many others. In a more sophisticated LCD bar graph, it could change color as it advances and retreats. All types of bar graphs can be utilized for the TLBG of the present invention and are considered to be included in the term TLBG.  
         [0048]    The preferred embodiment of the present invention utilizes a particular format for the TLBG  13  which is believed to be particularly adapted for the purposes of the present invention. A series of circles are provided disposed around a portion of the periphery of the computer display preferably at the top left thereof in the prominent display position for persons reading from left to right. The circles are located in the 9-12 o&#39;clock quadrant and progress in size in two dimensions as the TLBG increases to denote increasing tissue loading: they increase in size in both diameter and wall thickness. The smaller size circles are located at the lower end of the graph or scale and increase in dimensions with the nitrogen onloading. The circles increase in wall thickness to effect a larger presence as each circle appears on the display.  
         [0049]    [0049]FIG. 1 of the drawings shows the TLBG as it would be initially activated early in a dive. The smaller circles would appear alongside the green zone of the indicia on the computer case. FIG. 2 of the drawings shows the circles  39  which appear during a dive just before a diver enters a yellow caution zone due to a combination of his depth and duration underwater at variable depths as computed by the algorithm in the computer. FIG. 3 of the drawings shows the diver&#39;s condition represented by the circles  41  when he enters a decomposition (DECO) status denoted by the red indicia on the computer case. The DECO warning is illuminated and remains so until the diver goes through the DECO procedures in which case the TLBG will start to decrease.  
         [0050]    A computer means such as described in the Hollis &#39;678 patent is provided for integrating the output from the sensors according to an algorithm based on the Navy Dive Tables. The computer intakes the output from the various sensors and integrates it into various forms of information which are transmitted as computer output to the various data displays on the computer console. The only essential sensors for measuring tissue loading are the water depth transducer and elapsed time timer.  
         [0051]    A selection means is provided which is operable by a diver to select the value on the tissue loading bar graph for triggering at least one alarm when the preset value is reached during a dive by the output from the computer in response to integrating the output from the sensors. The alarms include an audible tone and a red LED warning light which illuminates on the display face above the top end of the TLBG. Both alarms are usually activated simultaneously.  
         [0052]    There are eight segments or circles in the tissue loading bar graph, in the preferred embodiment of the present invention, although more or less would serve the purpose. The circles extend for approximately a quarter of the periphery of the display face, or approximately 90 degrees, comparable to-from 9 o&#39;clock to 12 o&#39;clock on a watch face. The last segment is not a circle. It is a segment with the DECO warning printed thereon which appears when DECO is reached. The circles appear (and disappear) one by one progressively on the display as the tissue loading occurs or abates until (in the factory setting) the DECO segment appears and the LED and audible warning signals are activated.  
         [0053]    However, it is the purpose of the present invention that any one of the circles can be selected as the target value for activating the alarms. The computer is factory set for activating the alarms at DECO or when all eight segments have appeared on the TLBG. The alarm to indicate maximum acceptable tissue loading can be set to values between DECO (all eight segments) and a single segment. This is done during pre-dive setting of the computer while in the surface mode. By a combination of actuation of the advance and select buttons  23 ,  25 , a selected warning segment of the TLBG can be accepted as the warning segment for activating the alarms. The alarm setting based on the segments can be increased or decreased by actuation of the control buttons on the computer.  
         [0054]    In the preferred embodiment of the invention, the selection of the TLBG segment which will activate the alarms is set by pressing both buttons, advance  23  and select  25 , simultaneously. Then the advance (front) button is actuated and the units of the TLBG all appear with a set point flashing (appearing and disappearing). After the set point is flashing by the press and release of the advance button, that button is pressed eight more times. The graphic ndc and alarm (speaker) icon appear with the full TLBG flashing. Then the side button is pressed and released to decrease the number of segments individually one at the time. When the desired alarm setting is reached on the TLBG, the advance button is pressed to accept the setting and advance computer face to the set dive time remaining alarm or both buttons can be pressed for two seconds to revert to surface mode.  
         [0055]    The advantage of the present invention is that a diver can select from experience, or out of caution, a lower-level of tissue loading as a dive warning limit before he goes underwater. The selectable value is directly associated with the dive parameter which is most critical to a diver for avoiding DCS. None of prior devices provide this versatility in dive planning.  
         [0056]    Thus, it will be apparent from the foregoing description of the invention in its preferred form that it will fulfill all the objects and advantages attributable thereto. While it is illustrated and described in considerable detail herein, the invention is not to be limited to such details as have been set forth except as may be necessitated by the appended claims.