Abstract:
A distance measuring device measures distance by optically measuring the length of a flexible member, such as a line, as it is left off a reel. The line is provided with a plurality of dye marks spaced at predetermined increments. The dye marks are detected by an optical sensor. The optical sensor is operatively connected to a circuit which maintains a count indicative of the length of the line. The count is displayed on an LED display.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to measuring devices for measuring distance, and more particularly to optical measuring devices. 
     BACKGROUND OF THE INVENTION 
     Measuring devices for measuring distance comes in a variety of forms depending on their intended use. However, most measuring devices have several common characteristics. Measuring devices will typically include a measuring member having markings which correspond to predetermined units of measure. The measuring member may be rigid, such as a ruler, or flexible, such as a measuring tape. 
     While conventional measuring devices are quite useful for their intended purpose, they are nevertheless subject to certain limits. For example, rigid rules are useful primarily for measuring short distances of approximately three feet and under. Tape measures can be used to measure distances from zero feet to approximately 100 feet. However, tape measures in excess of 100 feet become large and cumbersome, and are therefore impractical. 
     There are also circumstances where rigid rules and flexible tapes are simply not suitable. For example, neither rigid rules nor tape measures are well suited for measuring the level or depth of water. For example, tape measures and rigid rules cannot be used for measuring the depth of a body of water such as a lake. Also, rigid rules and tape measures are not well suited for measuring the level of fluid in a tank which is accessible only through a small opening. 
     Based on the foregoing, it is apparent that a need exists for a versatile measuring device which can be used to measure short and long distances, and to measure the depth and/or level of a body of fluid. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     The distance measuring device of the present invention can be used to measure either short or long distances, and can be used to measure the depth or level of a fluid. The distance measuring device of the present invention comprises a flexible line or filament made from thermoplastic material such as nylon or polyester. The line includes a plurality of dye marks spaced at predetermined increments which correspond to the desired unit of measure. The line is wound on a reel which is contained within a housing. An opening is formed in the housing through which the line extends. An attachment suitable for the intended use is secured to the end of the line. For example, a small hook would be attached to the end of the line for measuring distances over land. A weight or float might be attached to the end of the line for measuring the depth or level of a fluid. 
     An optical sensor is disposed in the housing for detecting the dye marks on the line as the line passes by the sensor. The signal from the optical sensor is passed to a circuit which maintains a count indicative of the length of the line. The count is displayed on a LED display. 
     In a preferred embodiment of the invention, a pair of optical sensors are used to detect the direction the line is moving. A comparator circuit provides an &#34;up&#34; signal when the dye marks on the line pass the sensors in a first direction, and a &#34;down&#34; signal when the dye marks on the line pass the sensors in the opposite direction. The &#34;up&#34; and &#34;down&#34; signals from the comparator circuit are applied to a counter circuit which increments or decrements the display accordingly. 
     Based on the foregoing, it is a primary object of the present invention to provide a distance measuring device which is versatile in that it is well suited for measuring both short and long distances. 
     Another object of the present invention is to provide a distance measuring device which is adapted for measuring the depth or level of a fluid. 
     Still another object of the present invention is to provide a distance measuring device which is relatively simple in construction, durable in use, and economical to manufacture. 
     Yet another object of the present invention is to provide a distance measuring device having a relatively high degree of accuracy. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the distance measuring device of the present invention. 
     FIG. 2 is a section view of the distance measuring device. 
     FIG. 3 is a schematic diagram of the distance measuring device. 
     FIG. 4 is an electrical schematic illustrating the comparator circuit and counter circuit. 
     FIG. 5 is an electrical schematic illustrating the counter circuit. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and particularly to FIG. 1, the distance measuring device of the present invention is shown therein and indicated generally by the numeral 10. The distance measuring device 10 includes a casing 12 and a reel 14 mounted within the casing 12. A line 20 is wound on the reel 14 and projects through a line opening 18 in the casing 12. The reel 14 may include a crank 16 for winding the line 20 onto the reel 14. Alternatively, a small D.C. motor could be used for winding the reel 14. 
     The line 20 include a series of dye marks 22 which are spaced a predetermined distance from one another. The distance measuring device 10 optically &#34;reads&#34; the dye marks 22 when the line is paid out or reeled in, and either increments or decrements an LED display 30 on the exterior of the casing 12. 
     The dye marks 22 are produced by winding the line 22 onto a hollow tube having a narrow slot extending axially along the tube. After the line 20 is wound onto the tube, a disperse dye is heated to vaporize the dye and pumped through the tube. The dye filters through the narrow slot and impregnants the fishing line to produce the dye marks 22. The dye marks 22 will be spaced at a predetermined increment equal to the circumference of the tube. The length of the dye marks 22 will be determined by the width of the slot in the tube. The method for producing dye marks is described more fully in our co-pending patent application Ser. No. 07/989,699 filed on Dec. 14, 1992, which is incorporated herein by reference. 
     The casing includes an LED display 30 for displaying the measured distance. An &#34;on&#34;/&#34;off&#34; button 34 and reset button 32 are mounted on top of the casing 12. The function of the &#34;on&#34;/&#34;off&#34; button 34 and reset button 32 will be described below. 
     Referring now to FIG. 3, a pair of optical sensors 40 and 42 are disposed inside the casing 12 for detecting the dye marks 22 on the line 20. Each optical sensor includes an emitter, 40a and 42a, and a photoresistor, 40b and 42b, which are disposed on opposite sides of the channel 28. Each emitter 40a and 42a directs light across the channel 28 towards its respective photoresistor, 40b and 42b. The fishing line passes between the emitters, 40a and 42a, and the photoresistors, 40b and 42b. When a dye mark 102 on the fishing line passes between the emitter, 40a and 42a, and its respective photoresistor, 40b and 42b, transmission of the light is blocked. In this manner, the optical sensors 40 and 42 are able to detect the passing of each dye mark 102. 
     The sensors 40 and 42 are connected to a circuit shown in FIGS. 4 and 5. The comparator circuit 44 produces a pulse signal in response to the detection of a dye mark 22 on the line 20. The pulse signal is transmitted to the counter circuit 58 which maintains a count indicative of the length of the line 20. The counter circuit 58 is connected to an LED display 32 on which the count is displayed to the user. The LED display 30 has three digits 72a, 72b and 72c. 
     Referring now to FIG. 4, the comparator circuit 44 includes a pair of operational amplifiers 46 and 48, two flip flops 50 and 52, and two NAND gates 54 and 56. The input signal from each sensor, 40 and 42, is amplified by a respective amplifier 46 and 48. The first input signal from sensor 40 is applied to the input (D) of the flip flop 50 and to one-half of the NAND gate 54. The output signal (Q) from the flip flop 50 is applied to the other half of the NAND gate 54. Similarly, the second input signal from the sensor 42 is applied to the input (D) of the flip flop 52 and to one-half of the NAND gate 56. The output signal (Q) from the flip flop 52 is applied to the other half of the NAND gate 56. The flip flops 50 and 52 are synchronous and operate with a clock signal so that the input signals are valid and the corresponding state transitions are initiated only during a specific portion of a clock signal. The second input signal (i.e., the signal from sensor 42) serves as the clock signal for flip flop 50. Conversely, the first input signal (i.e. the signal from sensor 40) serves as the clock signal for the flip flop 52. 
     In operation, the comparator circuit 44 responds to the detection of a dye mark 22 and produces a pulse signal which is transmitted to the counter circuit 58. The pulse signal can be either an &#34;up&#34; signal or a down &#34;signal&#34; depending on the direction the line 20 is moving. When the line 20 is being paid out, the dye mark 22 on the line 20 will pass sensor 40 first, blocking the transmission of light from emitter 40a to the photoresistor 40b causing the photoresistor 40b to go HIGH. The input signal from the photoresistor 40b is amplified by the operational amplifier 46 and applied to the input (D) on the flip flop 50 and half the NAND gate 54. The output (Q) on the flip flop 50, which is passed to the other half of the NAND gate 54, remains LOW. When the dye mark 22 passes between the emitter 42a and the photoresistor 42b of sensor 42, the photoresistor 42b will provide a logical HIGH. The flip flop 50 is triggered by the rising pulse of the clock signal setting the output (Q) high. The input signal from sensor 40 must be stable during the rising portion of the clock cycle. Thus, the length of the dye mark 22 must be sufficient to simultaneously block both sensors 40 and 42. When the output of the flip flop 50 goes HIGH, the NAND gate 54 goes LOW since both inputs to the NAND gate 54 are HIGH. The output of the NAND gate 54 functions as an &#34;up&#34; signal which is transmitted to the counter circuit 58. The output of the NAND gate 54 is also fed back to the flip flop 50 to reset the flip flop 50. As a result, the output of the NAND gate switches back and forth from HIGH to LOW to HIGH again as each dye mark 22 passes, producing a pulsing &#34;up&#34; signal upon the passing of each dye mark 22 which increments the count. 
     When the line 20 is reeled in, the NAND 54 will remain in a steady state since the dye marks 22 will pass sensor 42 first. Since the output from sensor 40 is LOW, the rising pulse on sensor 42 will not change the value of the output (Q) on flip flop 50, and the state of the NAND gate 54 will not change. Thus, no pulse would be generated on NAND gate 54. 
     The flip-flop 52 operates in the same manner. When the line 20 is reeled in, the dye marks 22 will pass by sensor 42 first causing the output of sensor 42 to go HIGH. The input signal from sensor 42 is applied to one-half of the NAND gate 56 and to the input (Q) on the flip flop 52. When the dye mark 22 passes sensor 40, the rising pulse of the clock signal triggers the flip flop 52 setting the output (Q) HIGH. The output (Q) on the flip flop 52 is applied to the other half of the NAND gate 56 causing the output of the NAND gate 56 to go LOW. When the NAND gate 56 goes LOW, the flip-flop 52 is reset. This sequence is repeated each time a dye mark passes from B to A creating a pulsing &#34;down&#34; signal which decrements count as described below. 
     The output of the comparator circuit 44 is applied to the counter circuit 58 shown in FIG. 5. The counter circuit 58 includes three BCD counters 60, 62 and 64, and three drivers 66, 68 and 70 which drive respective digits on the LED display 30. The up/down signals from the comparator circuit 44 are applied to a first one of the BCD counters 60 which is connected to the driver 66 for the unit digits on the LED display 30. When the first digit exceeds nine, the carry bit on the first BCD counter 60 is set to increment the next digit. Conversely, when decrementing below zero, the borrow bit is set which causes the next digit to decrement by one and sets the units digit to nine. The BCD counters 62 and 64 for the tens digit and hundreds digit, respectively, operate in the same manner. 
     To prevent the LED display 30 from displaying preceding zeros, the RBI input on the driver chip 70 for the hundreds digit is connected to ground. Thus, the hundreds digit will be displayed only when it is non-zero. Similarly, the RBI input on the driver 68 for the tens digit is connected to a logic network 72 which causes the tens digits to be turned off when both the tens digit and hundreds digit are zero. When the hundreds digit is non-zero the tenths digit will be displayed even when zero. 
     The counter circuit 58 includes an &#34;on/off&#34; switch 76 which is actuated by the &#34;on/off&#34; button 34. The &#34;on/off&#34; switch 76 blanks the LED display 30. The meter 10 will continue to operate while the switch 76 is &#34;off&#34;, but will conserve power by not having to drive the LED display 30. When the switch 76 is turned &#34;on&#34;, the display 32 will show the correct values. A reset switch 74, which is actuated by the reset button 36, is provided to reset the count to zero. All circuit components are TTL devices which are powered off a five volt DC battery (not shown). If desired, a solar cell 36, shown in FIG. 1, could be used to recharge the batteries since most fishing is done during daylight hours. Using a solar cell 36 to recharge the batteries would obviate the need to periodically exchange batteries. 
     The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.