THE MEASURING INSTRUMENT OF THE DEPTH OF WATER Technical Field The present invention relates generally to a water depth measuring device, which has been invented by improving"the water depth measuring device"disclosed in Korean Patent Application No. 2001-25320 filed by the inventor of the present invention and used as a basis for the priority of the present invention, and which is designed such that it more precisely measures a depth of water and is preferably used in a variety of industrial fields. More particularly, the present invention relates to a portable device for measuring a depth of water, which is designed to easily, accurately and automatically measure a depth of water, and which allows a user to easily confirm a measured value and a position of the device at night time, and which is designed to indicate to a user that the measurement is completed and to allow a user to rapidly withdraw the device, thus allowing a user to accurately confirm a measured value, and being easy to carry, maintain, and use, and accomplishing high accuracy.

Background Art Light, air, soil, heat, light energy, water, and others are critical elements which are indispensable for all kinds of creatures existing on the Earth, and cannot be replaced with other elements. Of these, water is not only a concrete and measurable resource which is capable of supplying a measurable amount of energy, such as petroleum, land, and minerals, but is also a formless and immeasurable resource enhancing human lives.

That is, a swim in a clear lake invigorates humans, and a quietly flowing river is inhabited by a variety of creatures, and besides, serves as a means of transportation for

humans. The value of water as a resource is different from other resources in its characteristics. In the case of resources other than water, it is possible to estimate development limits by measuring their reserves. However, a water resource is a circulating inexhaustible resource, and most water resources are obtained from outflow of rainfall in river valleys. Thus, since annual precipitation is not constant, the amount of water usable as a resource fluctuates.

Most resources are cumulatively reduced in their amount as they are used, but water can be renewably obtained from rivers without a great change in its amount, so water resources are infinite. Thus, water is a so-called inexhaustible resource. That is, water used for generating electricity at an upstream location is also used as agricultural water, industrial water, and living water at a downstream location, and waste water penetrates underground to constitute ground water, and then the ground water is reused by pumping up the water.

Today, the annual precipitation in Korea amounts to about 1,159.2mm. This amount is more than the average precipitation of world, that is, 730mm, by 60%, but water of 3,100 mm3 per person is available, which corresponds to only one tenth the per capita availability of other countries. Since rainfall amounting to two thirds of the annual precipitation falls from June to August, most of water overflows in the form of floods, and only 23% of total amount of water is used. According to estimates made by experts, amount of ground water reserves is about 232,000,000,000m3, but this water layer is thin and it is inefficient to exploit in an economic point of view, so it is not developed as a useful resource.

As such, water is a critical resource essential to all creatures, and besides, water is a raw material indispensable for the production of common industrial products. In other words, about 350g of water is absolutely required to produce lg of rice, 150t of water is required to produce It of newspaper print. Further, 285-fold, 25-fold, 2,000-

fold by weight of water is required to produce iron, gasoline, and rayon, respectively.

When water continuously flows at a flow rate of l. Om3/s in a river which has a depth of 50m, electrical energy of 353 kW can be generated. For example, when lmm of rain falls in the area around the SOYANG river of Korea, 2,700,000m3 of water collects in the SOYANG lake. This amount is equivalent to forty million won when converted into the price of electricity. This water flows downstream and joins the Han river, thus forming fine scenery, invigorating humans and providing homes where aquatic creatures lead their lives.

Such a value of water is not limited to a concrete value, that is, the value of water as agricultural water, industrial water, and living water. Water has another value more important than the concrete value. Thus, the development of the national economy and a high standard of life depend on how systemically and efficiently water is managed, so many countries of the world have made efforts to thoroughly manage and efficiently use their water resources.

As such, in order to systemically and efficiently manage water resources, it is required to accurately measure a depth of water, including a pond, a reservoir, a lake, a river, ground water, and a sea. Such a measuring result can be utilized as data for preventing and coping with a flood disaster, and for various other purposes. In order to accurately measure a depth of water, there have been proposed a variety of devices for measuring a depth of water.

As described above, many devices for measuring a depth of water have been developed and used. Of these, a device for measuring a depth of water using laser beams has been disclosed in Korean Patent No. 213599. This conventional device will be described with reference to FIGS. 12A and 12B.

The method of measuring a depth of water by reflecting laser beams is as follows. First, a pipe 20 is installed in a reservoir while inclined at a predetermined

angle. In this case, a buoyant body 30 reflecting light is received in the pipe 20 in such a way as to move along the water's surface. Next, a laser beam generator 10 radiates laser beams toward the buoyant body 30. At this time, the buoyant body 30 reflects the laser beams. By detecting the arrival time of the laser beams, the depth of water is measured.

In this case, the conventional device includes the laser beam generator 10, the hollow pipe 20, and the buoyant body 30. The pipe 20 is connected to the laser beam generator 10. The buoyant body 30 is movably received in the pipe 20, and coated with a light reflecting material.

The end 21 of the pipe 20 is inwardly bent so as to prevent the buoyant body 30 from being removed from the pipe 20. The buoyant body 30 is formed by plating a chromium layer 32 on a ball 31. In this case, the chromium layer 32 has high reflectivity and the ball 31 is made of synthetic resin.

The conventional device for measuring a depth of water using laser beams is simple in its construction and is easy to use, in comparison with other conventional devices.

However, the conventional device for measuring a depth of water using laser beams has a problem that it is difficult to install in water and to carry, because a pipe must have a length and a diameter sufficient to reach the bottom of a measured body of water, such as a reservoir.

This conventional device must be provided with additional devices, including a laser beam generator, a result reading unit and a laser beam detecting unit. Further, a single pipe having a length of about 50-lOOm or a plurality of pipes each having a length of about 1~2m and assembled with each other are required to measure the maximum water level of a reservoir. Thus, the conventional device has another problem that it is difficult to carry and inconvenient to measure a depth of water, and the cost of carrying,

installation, measurement, and maintenance is high.

The conventional device has a further problem that it is difficult to change a target position to be measured, because it is almost impossible to move when a plurality of pipes are assembled with each other. Thus, when it is desired to change a target position to be measured, the pipes must be disassembled and reassembled, so it is very inconvenient to measure a depth of water using the conventional device. Further, the conventional device is limited in measuring objects, so it is impossible to be used for various purposes. Thus, the conventional device cannot meet various requirements of consumers, and thus marketability thereof is low.

Disclosure of the Invention Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a water depth measuring device, which has been invented by improving"the water depth measuring device"disclosed in Korean Patent Application No. 2001-23520 filed by the inventor of the present invention and used as a basis for the priority of the present invention, and which is designed to easily, accurately and automatically measure a depth of water, and which allows a user to easily confirm a measured value and a position of the device at night time, and which is designed to indicate to a user that the measurement is completed and to allow a user to rapidly withdraw the device, thus allowing a user to accurately confirm a measured value, and being easy to carry, maintain, and use, and accomplishing high accuracy, and thus being conveniently used in a variety of fields.

In order to accomplish the above object, the present invention provides a portable device for measuring a depth of water, comprising an upper cap having a hollow hemisphere shape, and bored at a center of the top thereof for receiving an upper

guide pipe, the upper guide pipe being vertically and downwardly extending to a predetermined position, the upper cap designed such that it is open at its bottom and its lower internal surface is threaded ; a lower cap having an inverted cone shape to have a mounting space, and being open at the top thereof, the lower cap designed such that its upper internal surface is threaded, and provided at a center of the bottom thereof with a lower guide pipe, the lower guide pipe being vertically and upwardly extending to a predetermined position; a main body having a cylindrical shape, and consisting of a hollow mounting space having a battery therein and being open at the top thereof, a window frame provided at a wall cut in a predetermined size of the main body, upper and lower portions corresponding to the upper and lower caps in their shape to engage with them, a hollow main guide pipe being open at top and bottom thereof and uprightly set in such a way as to be coaxially aligned with the upper and lower guide pipes, and a support step having a predetermined length and interiorly formed on an upper portion of the main body in such a way as to be protruded toward the center of the main body; a detecting means mounting plate seated on upper surface of the support step of the main body in such a way as to be in close contact with the upper surface of the support step, and consisting of two support walls provided at two positions spaced from a center of said mounting plate by a predetermined length in such a way as to be upwardly projected and each having a pin insertion hole, a hole formed at the center of the mounting plate such the main guide pipe passes through the hole, and a sensor seat provided at a surface of the mounting plate ; detecting means consisting of two sensors oppositely seated on an upper surface of the sensor seat of the detecting means mounting plate in such a way as to be spaced apart from each other by a predetermined interval and connected to a battery used as a power supply such that electric power of the battery is supplied to the sensors, and a rotary unit of a bone shape having a guide groove formed along the center line on an outer circumference of the rotary unit, an anti-slip rubber fitted over the guide

groove, and a detecting disc placed between the two sensors, and a pin passing through the center portion of the rotary unit and rotatably inserted into the pin insertion holes of the support walls; output means consisting of a liquid crystal display (LCD) mounted to an inner surface of the window frame through the mounting space of the main body and displaying inputted data so as to allow a user to easily confirm and read the inputted data when electric power is supplied to the device and various data are inputted; measuring means consisting of a measuring wire having a predetermined length and wound around a bobbin in such a way as to be automatically or manually unwound from the bobbin as required and sequentially passing through the upper guide pipe of the upper cap, the guide groove of the rotary unit, the main guide pipe of the main body, and the lower guide pipe of the lower cap, and a measuring weight provided at a lower end of the measuring wire ; illuminating means consisting of a plurality of light emitting diodes (LEDs) connected to the power supply, arranged on the detecting means mounting plate at a predetermined interval, and selectively turned on in response to an electrical signal for allowing a user to easily confirm a measuring position and measuring data in the dark or at night, and at least one lamp provided at a position on the LCD to be selectively turned on; and control means (CPU) mounted at a predetermined position in the mounting space of the main body, and performing the steps of receiving various data, and controlling the power supply, transmitting the data in the form of electric signals to the output and illuminating means, displaying a measured depth of water on the LCD, selectively supplying electric power to the device so as to turn the illuminating means on or off according to a preset input value of the LEDs or the lamp, checking a charged state of the battery, displaying the charged state of the battery on the LCD, and resetting the LCD to an initial state after confirming the measured depth of water.

Further, the present invention provides a portable device for measuring a depth of water, comprising an upper cap having a hollow hemisphere shape and bored at a

center of the top thereof for receiving an upper guide pipe, the upper guide pipe vertically and downwardly extending to a predetermined position, the upper cap designed such that it is open at its bottom and a lower inner surface thereof is threaded; a lower cap being open at the top thereof, having a mounting space, and designed such that an upper internal surface thereof is threaded, and consisting of a lower guide pipe set in a bore formed on a center of the bottom of the lower cap and vertically and upwardly extending to a predetermined position, a plurality of holding members integrally formed at a lower surface of the lower cap in such a way as to be set vertically and upwardly thereat, and a display and a control unit each having a printed circuit board and provided on an external surface of the lower cap; a detecting unit having a disc shape, rotated by a friction force generated while guiding a measuring wire, and designed such that a magnet is received in a wall of the detecting unit ; a cover plate consisting of two support pieces set on the top surface of the cover plate for receiving the detecting unit between the two support pieces, with a magnetic detector installed in one of the two support pieces for detecting a signal generated by a rotation of the magnet, a battery cover integrally formed on the cover plate along a circumference thereof in such a way as to be upwardly protruded and covering upper portions of batteries, a plurality of LEDs having high luminous intensity, and a guide pipe integrally and downwardly extending from the cover plate; a battery holding plate consisting of a plurality of battery holding holes, two printed circuit board holding slots, and a guide hole formed on the center of the battery holding plate for guiding the guide pipe of the cover plate ; a plurality of battery terminal holders; and a holder support unit for supporting the battery terminal holders.

The portable device for measuring a depth of water of this invention can be thrown into a measuring place with only simple manipulation without requiring additional equipments or a preliminary step, and allows a user to easily read and confirm

a measured value, thus being easy and convenient to use, and is compact and light in weight, thus being easy to carry and maintain.

The portable device for measuring a depth of water of this invention is also capable of conveniently measuring a depth of water without requiring additional preliminary operations, such as assembling and transporting operations, thus being rapidly moved to a desired place, reducing a measuring time, and thus being efficient in terms of economy.

The portable device for measuring a depth of water of this invention is convenient to carry and use, thus easily measuring a depth of water while easily changing a position of a measured object as desired, therefore being utilized for various purposes, including fishing and aquatic sports, and is also useful to measure a height of a building or a structure, etc., thus ensuring high marketability, meeting a variety of requirements of consumers, and accurately measuring the depth or height of a target according to various purposes.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is a perspective view showing a portable device for measuring a depth of water according to the primary embodiment of this invention ; FIG. 2 is an exploded perspective view of the portable device for measuring a depth of water of this invention ; FIG. 3 is a sectional view of the portable device for measuring a depth of water of this invention, with a measuring wire assembled with a measuring unit ;

FIG. 4 is a partial sectional view of the portable device for measuring a depth of water of this invention, when the measuring wire moves along a guide groove of a rotating unit; FIG. 5 is an exploded perspective view showing a portable device for measuring a depth of water in accordance with the second embodiment of this invention; FIG. 6 is a sectional view of the portable device for measuring a depth of water of FIG. 5; FIG. 7 is a perspective view of the portable device for measuring a depth of water of FIG. 5, with the parts of the device being assembled into a single structure; FIG. 8 is an enlarged sectional view of the upper portion of the portable device for measuring a depth of water of FIG. 5 ; FIG. 9 is an enlarged sectional view of the upper portion of the portable device for measuring a depth of water according to a modification of FIG. 8; FIG. 10A is an exploded perspective view showing a portable device for measuring a depth of water according to another modification of the second embodiment of this invention; FIG. 1 OB is an enlarged sectional view of the upper portion of the portable device for measuring a depth of water of FIG. 10A ; FIGS. 1lA and 11B are views showing the portable device for measuring a depth of water of this invention, in which the device is operated; and FIGS. 12A and 12B are a view of a conventional device for measuring a depth of water using a laser beam and installed in water, and a partial sectional view thereof, respectively.

Best Mode for Carrying Out the Invention

Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

(Primary embodiment) FIG. 1 is a perspective view showing a portable device for measuring a depth of water according to the primary embodiment of this invention. FIG. 2 is an exploded perspective view of the portable device for measuring a depth of water of this invention.

FIG. 3 is a sectional view of the portable device for measuring a depth of water of this invention, with a measuring wire assembled with a measuring unit. FIG. 4 is a partial sectional view of the portable device for measuring a depth of water of this invention, when the measuring wire moves along a guide groove of a rotating unit. FIGS. 11 A and 11 B are views showing the portable device for measuring a depth of water of this invention, in which the device is operated.

As shown in the drawings, the device of this invention comprises a measuring device 100 including upper and lower caps 110 and 120, a main body 130, a detecting means mounting plate 140, a detecting means 150, an output means 160, an illuminating means 180, and a control means 190. The device also comprises a measuring means 170. In this case, the upper and lower caps 110 and 120 of the measuring unit 100 each have a predetermined shape, and are provided with an upper guide pipe 111 and a lower guide pipe 121, respectively. The main body 130 has a mounting space 131 therein.

A window frame 132 is provided at the sidewall of the main body 130. The main body 130 is designed such that its upper and lower portions correspond to the upper and lower caps 110 and 120 in their shapes to engage with them. A main guide pipe 133 and a battery B are set on the bottom of the main body 130. A support step 134 having a

predetermined length is interiorly formed on the upper portion of the main body 130.

The detecting means mounting plate 140 is provided with two support walls 141, a hole 142, and a sensor seat 143. A pin insertion hole 141a is formed on each of the support walls 141. The hole 142 is formed at the center of the mounting plate 140. The sensor seat 143 is provided at a predetermined position of the mounting plate 140. The detecting means 150 consists of two sensors 151, a rotary unit 152, and a pin 153. In this case, the two sensors 151 are oppositely seated on the sensor seat 143 of the detecting means mounting plate 140, and are connected to a battery B used as a power supply such that electric power of the battery is supplied to the sensors 151. The rotary unit 152 has a guide groove 152a, an anti-slip rubber 152c, and a detecting disc 152b.

The guide groove 152a is formed along a center line on the outer circumference of the rotary unit 152. The anti-slip rubber 152c is fitted over the guide groove 152a. The detecting disc 152 is placed between the two sensors 151. The pin 153 passes through the center portion of the rotary unit 152, and both ends of the pin 153 are supported by the support walls 141. The output means 160 consists of a liquid crystal display (LCD) 161. The LCD 161 is mounted to the window frame 132 of the main body 130, and displays input data so as to allow a user to easily read the input data when electric power is supplied to the device and various data are inputted. The measuring means 170 consists of a measuring wire 171, and a measuring weight 172. The measuring wire 171 has a predetermined length, and is wound around a bobbin (not shown), and sequentially passes through the upper cap 110, the main body 130, and the lower cap 120 while passing over the rubber 152c of the rotary unit 152 at a position between the upper cap 110 and the main body 130. The measuring weight 172 is provided at the lower end of the measuring wire 171. The illuminating means 180 consists of a plurality of light emitting diodes (LEDs) 181, and at least one lamp 182. The LEDs 181 are arranged on the detecting means mounting plate 140 at predetermined regular intervals.

The lamp 182 is provided at a position on the LCD 161 to be selectively turned on.

The control means 190 performs the steps of receiving various data, and controlling the power supply, transmitting the data in the form of electric signals to the output and illuminating means 160 and 180, displaying a measured depth of water on the LCD 161, selectively supplying electric power to the device so as to turn the illuminating means 180 on or off according to a preset input value of the LEDs 181 or the lamp 182, checking the charged state of the battery B, displaying the charged state of the battery B on the LCD, and resetting the LCD 161 to an initial state after a user confirms the measured depth of water.

The upper cap 110 has a hollow hemispherical shape, and is bored at the center of its top for receiving the upper guide pipe 111. The upper guide pipe 111 vertically and downwardly extends to a predetermined position. The upper cap 110 is designed such that it is open at its bottom and a lower internal surface thereof is threaded.

In this case, the upper cap 110 is made of a transparent or translucent material.

Further, a variety of designs and colors may be entirely or partially applied to the outer surface of the upper cap 110.

The lower cap 120 has an inverted cone shape while being open at its top, and has a mounting space 122 therein. The lower cap 120 is designed such that its upper internal surface is threaded, and is provided at the center of its bottom with the lower guide pipe 121. The lower guide pipe 121 vertically and upwardly extends to a predetermined position.

In this case, a weight 123 may be additionally received in the mounting space 122 of the lower cap 120 so as to put the center of gravity of the measuring unit 100 at the lower portion of the unit 100. Thus, when the measuring unit 100 is installed in the water, the weight 123 causes the measuring unit 100 to be perpendicular to the surface of water. In this case, the weight 123 has a shape corresponding to the mounting space

122 to be received in said mounting space 122.

The main body 130 has a cylindrical shape, and consists of the mounting space 131, the window frame 132, the hollow main guide pipe 133, and the two support steps t 134. The mounting space 131 is hollow and open at the top. The window frame 132 is provided at the sidewall of the main body 130. In this case, the sidewall of the main body 130 is cut in a predetermined size for installing the window frame 132 in the cutout. The upper and lower portions of the main body 130 correspond to the upper and lower caps 110 and 120 in their shape to firmly engage with them. The hollow main guide pipe 133 is open at its top and bottom, and uprightly set in such a way as to be coaxially aligned with the upper and lower guide pipes 111 and 121. The two support steps 134 each have a predetermined length, and are interiorly formed on the upper portion of the main body 130 in such a way as to be protruded toward the center of the main body 130.

The main body 130 is provided with sealing members 135 at junctions between the main body 130 and the upper cap 110 and between the main body 130 and the lower cap 120 so as to prevent water from flowing into the mounting space 131 of the main body 130 during measurement of a depth of water. The main body 130 is designed to be perpendicular to a water's surface while allowing the bottom of the upper cap 110 to be aligned with the water's surface. The battery B is removably provided at a predetermined position of the lower portion of the main body 130 such that the center of gravity of the main body 130 is placed at the lower portion of the main body 130. A battery holding plate B1 is provided on the lower guide pipe 121 of the lower cap 120 so as to prevent the battery B from being undesirably removed from the main body 130.

The main body 130 also has a sub power button 136A, a reset button 136B, a control button 136C, and a main power button 136D. The sub power button 136A is used for selectively turning on the LEDs 181 or the lamp 182. The reset button 136B is

used for resetting the LCD 161 after a user confirms a measured value displayed on the LCD 161. The control button 136C is used for controlling a variety of functions of the device as desired. The main power button 136D is used for selectively turning on the device. In this case, the buttons 136A, 136B, 136C, and 136D are provided at predetermined positions on the external surface of the main body 130 such that the buttons are waterproofed and allow a user to selectively control the device from the outside of the body 130. In addition, the main body 130 also has an LCD protecting panel 137 so as to prevent the external surface of the LCD 161 mounted to the window frame 132 from being damaged.

The detecting means mounting plate 140 is seated on the upper surface of the support step 134 of the main body 130 in such a way as to be in close contact with the upper surface of the support step 134, and consists of the two support walls 141, the hole 142, and the sensor seat 143. In this case, the two support walls 141 are provided at two positions spaced from the center of the mounting plate 140 by a predetermined length in such a way as to be upwardly projected, and each have the pin insertion hole 141a. The hole 142 is formed at the center of the mounting plate 140 such the main guide pipe 133 passes through the hole 142. The sensor seat 143 is provided at a surface of the mounting plate 140.

The detecting means 150 includes the two sensors 151, the rotary unit 152, and the pin 153. The two sensors 151 are oppositely seated on the upper surface of the sensor seat 143 of the detecting means mounting plate 140 in such a way as to be spaced apart from each other by a predetermined interval, and connected to the battery B such that electric power of the battery B is supplied to the sensors 151. The rotary unit 152 of a bone shape has the guide groove 152a, the anti-slip rubber 152c, and the detecting disc 152b. The guide groove 152a is formed along the center line on the outer circumference of the rotary unit 152. The anti-slip rubber 152c is fitted over the guide

groove 152a. The detecting disc 152b is placed between the two sensors 151. The pin 153 passes through the center portion of the rotary unit 152 and is rotatably inserted into the pin insertion holes 141 a of the support walls 141.

The measuring wire 172 vertically moving during measurement of a depth of water, passes over the anti-slip rubber 152c fitted over the guide groove 152a of the rotary unit 152 of the detecting means 150 at a position offset from the hole 142 of the detecting means mounting plate 140 so as to be prevented from slipping, thus obtaining a more accurate measured value.

The output means 160 consists of the liquid crystal display (LCD) 161. The LCD 161 is mounted to the inner surface of the window frame 132 through the mounting space 131 of the main body 130, and displays input data so as to allow a user to easily confirm and read the input data when electric power is supplied to the device and various data are inputted The measuring means 170 consists of the measuring wire 171, and the measuring weight 172. The measuring wire 171 has a predetermined length, and is wound around the bobbin (not shown) in such a way as to be automatically or manually unwound from the bobbin as required, and sequentially passes through the upper guide pipe 111 of the upper cap 110, the guide groove 152a of the rotary unit 152, the main guide pipe 133 of the main body 130, and the lower guide pipe 121 of the lower cap 120.

The measuring weight 172 is provided at the lower end of the measuring wire 171.

The illuminating means 180 consists of the light emitting diodes (LEDs) 181, and at least one lamp 182. The LEDs 181 are connected to the power supply, arranged on the detecting means mounting plate 140 at a predetermined interval, and selectively turned on in response to an electrical signal for allowing a user to easily confirm a measuring position and measuring data in the dark or at night. The lamp 182 is provided at a position on the LCD 161 to be selectively turned on.

The control means (CPU) 190 is mounted at a predetermined position in the mounting space 131 of the main body 130. The control means 190 performs the steps of receiving various data, and controlling the power supply, transmitting the data in the form of electric signals to the output and illuminating means 160 and 180, displaying a measured depth of water on the LCD 161, selectively supplying electric power to the device so as to turn the illuminating means 180 on or off according to a preset input value of the LEDs 181 or the lampl82, checking the charged state of the battery B, displaying the charged state of the battery B on the LCD 161, and resetting the LCD 161 to an initial state after a user confirms the measured depth of water.

The control means 190 controls the LEDs 181 or the lamp 182 provided at a position on the LCD 161 such that the LEDs 181 or the lamp 182 is repeatedly turned on and turned off, or generates an alarm sound when the battery has to be replaced with a new one. The upper and lower caps 110 and 120 or the main body 130 are made of a buoyant material.

Further, the bobbin (not shown) is operated by a drive motor which is rotated in alternating directions such that the measuring wire 71 is automatically wound around the bobbin. The bobbin is normally held by a latch, but is released when throwing the measuring unit 100 to measure the depth or the height of a target. When the bobbin is released, the measuring wire 171 is unwound to reach a desired position by the measuring weight 172. After finishing measuring a depth of water, a user presses a switch for winding the measuring wire 171 on the bobbin and returning the measuring unit 100 and the measuring wire 171 to their original states.

Further, a sensor for detecting temperature may be mounted to the outer surface of the main body 130 and/or the measuring weight 172 so as to simultaneously measure a depth as well as a temperature of water. When two sensors for detecting temperature are mounted to the outer surfaces of the main body 130 and the measuring weight 172,

respectively, a user can measure the temperatures of the surface and the bottom of water at the same time.

The assembling operation and use of the portable device for measuring a depth of water constructed in this way is as follows.

First, the measuring means 170 is assembled with the measuring unit 100 such that the measuring wire 171 which is, at its end, connected to the measuring wire 171 passes sequentially through the upper guide pipe 111 of the upper cap 110, the main guide pipe 133 of the main body 130, and the lower guide pipe 121 of the lower cap 120.

At this time, the measuring wire 171 passes over the anti-slip rubber 152c fitted over the guide groove 152a of the rotary unit 152 while being in frictional contact with the rubber 152c. The measuring weight 172 is firmly connected to the end of the measuring wire 171. When assembling the main body 130 with the upper and lower caps 110 and 120 to form the measuring unit 100, the sealing members 135 each are provided at a junction of the upper portion of the main body 130 and the upper cap 110, and at a junction of the lower portion of the main body 130 and the lower cap 120 so as to prevent foreign materials or water from flowing into the main body 130 during the measurement of a depth of water.

As such, after assembling the measuring unit 100 with the measuring means 170 so as to measure a depth of water at a desired place, a user turns on the main power button 136D to supply electric power to the measuring unit 100 and throws the measuring unit 100 along with the measuring weight 172 at a target point. When they come into contact with the surface of water, the measuring unit 100 floats on the surface of water by its own buoyancy but the measuring weight 172 connected to the end of the measuring wire 171 sinks into the water and reaches the bottom by its own weight. At this time, the measuring wire 171 is unwound from the bobbin (not shown) while moving down together with the measuring weight 172. In this case, since the

measuring wire 171 frictionally passing over the rubber 152c of the rotary unit 152 moves together with the measuring weight 172, the rotary unit 152 is rotated in the same direction as the moving direction of the wire 171. The sensors 151 sense the number of rotations of the detecting disc 152b of the rotary unit 152. When the measuring weight 172 reaches the bottom of water, the measuring wire 171 stops moving, and thus the rotary unit 152 stops rotating. If such a stop state continues for a predetermined period of time, a user decides that the measurement of a depth of water is completed.

As such, when the number of rotations of the detecting disc 152b is sensed by the sensors 151 and the rotary unit 152 stops rotating for a predetermined period of time, a measured value is detected and then the value is transmitted to the control means 190.

In order to allow a user to confirm a measured data which is read by a logic operation based on the transmitted data, the measured value is displayed on the LCD 161, and simultaneously the LEDs 181 of the illuminating means 180 turn on or an alarm sound is generated for indicating to a user that the measurement is completed. Next, as the measuring wire 171 is wound around the bobbin by a winding device or by a user, the measuring weight 172 sinking in the water rises to the water's surface. When the measuring weight 172 reaches the bottom of the measuring unit 100, the user pulls the measuring unit 100 together with the measuring weight 172. At this time, the user easily and accurately confirms the measured value through the LCD 161 exteriorly provided at the surface of the main body 130 of the measuring unit 100.

The main body 130 is provided at predetermined positions on its external surface with buttons 136A, 136B, 136C, and 136D. The sub power button 136A is turned on at night or in the dark such that a user easily confirms data displayed on the LCD 161. The reset button 136B is used for resetting the LCD 161 to an initial state.

The control button 136C is used for setting time and controlling various modes, that is, for setting an illuminating time of the lamp 182 and a radiating time of the LEDs 181, an

automatic or manual mode, an alarm sound generating mode, and a memory mode of a measured value. The main power button 136D is used for selectively turning on the device.

The portable device for measuring a depth of water according to this invention can be used for other purposes. When it is desired to use the device for other purposes, the measuring unit 100 is held by a user, and the measuring wire 171 is unwound from the bobbin and moves downwardly by the measuring weight 172. At this time the rotary unit 152 is rotated, and a measured value detected by the sensors 151 is displayed on the LCD 161. Thus, the heights of various structures, including buildings, can be easily and accurately measured by the device of this invention. Further, a fishing line and a fishing sinlcer may be used in place of the measuring wire 171 and the measuring weight 172. When they are assembled with the measuring unit 100, a depth of water can be easily and accurately measured, thus allowing a fisher to put a float at an optimum position of the fishing line. So, even beginners can enjoy fishing without great difficulty in putting a bob or a hook on the fishing line, and so the device of this invention is ideally used for fishing. In addition, the device of this invention can be used for a variety of purposes, including water sports.

(Second embodiment) The second embodiment of this invention is shown in FIGS. 5 to I OB.

FIG. 5 is an exploded perspective view showing a portable device for measuring a depth of water in accordance with the second embodiment of this invention.

FIG. 6 is a sectional view of the portable device for measuring a depth of water of FIG.

5. FIG. 7 is a perspective view of the portable device for measuring a depth of water of FIG. 5, with a measuring unit being assembled with a measuring means. FIG. 8 is an

enlarged sectional view of the upper portion of the portable device for measuring a depth of water of FIG. 5. FIG. 9 is an enlarged sectional view of the upper portion of the portable device for measuring a depth of water according to a modification of FIG. 8.

FIG. 10A is an exploded perspective view showing a portable device for measuring a depth of water according to another modification of the second embodiment of this invention. FIG. 1 OB is an enlarged sectional view of the upper portion of the portable device for measuring a depth of water of FIG. 1 OA.

As shown in the drawings, according to the second embodiment of this invention, a measuring unit 200 includes an upper cap 210, a lower cap 270, a cover plate 230, a detecting unit 220, a plurality of battery terminal holders 250¢ and a holder support unit 260. In this case, the cover plate 230 is positioned above the lower cap 270. The detecting unit 220 is placed on the upper surface of the cover plate 230 for detecting the movement of a measuring wire 171. The battery terminal holders 250 hold batteries B.

As shown in FIG. 10A, the measuring unit 200 preferably has a cover 300 for covering the detecting unit 220. The cover 300 consists of a first cover part 310, a second cover part 311, a wire guide pipe 314, a locking hole 313, a locking projection 312, and a pin hole 315. The first cover part 310 covers one surface of the detecting unit 220, while the second cover part 311 covers the other surface of the detecting unit 220. The wire guide pipe 314 is provided at the junction of the first and second cover parts 310 and 311 such that the measuring wire 171 passes through the wire guide pipe 314. The locking hole 313 is formed on the first cover part 310, while the locking projection 312 is formed on the second cover part 311. The pin holes 315 are formed at centers of the first and second cover parts 310 and 311.

The upper cap 210 is made of a translucent material, and has a hemispherical shape while being open at the bottom. The lower internal surface of the upper cap 210

is internally threaded. A bore 212 is formed on the top of the upper cap 210 such that the measuring wire 171 passes through the bore 212. In addition, a guide cap 211 is inserted into the bore 212 for guiding the measuring wire 171.

The lower cap 270 has an inverted cone shape while being open at the top.

The upper external surface of the lower cap 270 is externally threaded to engage with the upper cap 210. A display 271 and a control unit 272 each having a printed circuit board (PCB) are provided on the external surface of the lower cap 270. A bore 274 is formed on the bottom of the lower cap 270 such that the measuring wire 171 passes through the bore 274. A hollow protrusion 278 is internally integrated with the lower cap 270 along the circumference of the bore 274.

A guide pipe 238 of the cover plate 230 is fitted into the hollow protrusion 278.

A sealing member 275 consisting of an O-ring 276 is interiorly mounted to the hollow protrusion 278 to seal the guide pipe 238. That is, the guide pipe 238 of the cover plate 230 is received in the sealing member 275 installed in the protrusion 278 to keep the guide pipe 238 airtight and watertight, thus preventing water from flowing into the measuring unit 200.

The control unit 272 serves the same function as the control means of the first embodiment. The display 271 displays a value inputted from the control unit 272, that is, a value indicating a measured depth of water so that a user can confirm the measured value.

A holding pin 273 is integrally formed in the lower portion of the lower cap 270 to hold a holder support unit 260 which supports battery terminal holders 250.

The cover plate 230 is seated on the lower cap 270. A battery cover 231 is integrally formed on the cover plate 230 in such a way as to be upwardly protruded, and covers the upper portions of the batteries B. A guide hole 239 is formed on the center of the cover plate 230 such that the measuring wire 171 passes through the cover plate

230. Two support pieces 223 are set at two positions around the guide hole 239, and are provided on the upper portions with pin holes 235. Further, a magnetic switch holding part 236 is integrally formed on a surface of one of the two support pieces 223.

A plurality of LEDs 232 having high luminous intensity are provided on the cover plate 230, and are turned on or off in response to signals outputted from the control unit 272, thus allowing a user to easily read the position of the measuring unit 200 and measuring data.

A guide pipe 238 having a rod shape integrally and downwardly extends from the cover plate 230. The guide pipe 238 serves to guide the measuring wire 171 and allows the cover plate 230 to be easily positioned in its place when inserting the cover plate 230 into the lower cap 270.

The detecting unit 220 has a disc shape, and is supported by two support pieces 223 which are oppositely set on the center portion of the cover plate 230. The measuring wire 171 passes over the detecting unit 220 while generating a frictional force. At this time, a signal outputted from the detecting unit 220 is operated by the control unit 272, and then is displayed on the display 271.

Preferably, as shown in FIGS. lOA and 10B, the detecting unit 220 covered with a cover 300 is supported by the support pieces 223 which are set at positions offset from the center of the cover plate 230. When the measuring wire 171 passes through the wire guide pipe 314 provided at the junction of the first and second cover parts 310 and 311 of the cover 300, and is wound around the guide groove 223 of the detecting unit 220, a frictional force is generated. Since the measuring wire 171 passes through the wire guide pipe 314 and the cover 300 covers the detecting unit 220, the measuring wire 171 stably moves along the guide groove 223 of the detecting unit 220 without being removed from the detecting unit 220, so the signal from the detecting unit 220 can be completely operated by the control unit 272 and then be displayed on the display 271.

As such, the detecting unit 220 without having the cover 300 or the detecting unit 220 covered with the cover 300 is interposed between the support pieces 233, and is shafted to the supported pieces 233 by the pin 235. In the case where the detecting unit 220 is not covered with the cover 300, the pin 235 is inserted to the pin holes 234 of the support pieces 233. On the other hand, in the case where the detecting unit 220 is covered with the cover 300, the pin 235 is inserted to both the pin holes 234 of the support pieces 233 and the pin holes 315 of the cover 300. When the measuring wire 171 moves along the guide groove 223 of the detecting unit 220, a frictional force is generated. By the frictional force, the detecting unit 220 rotates around the pin 235.

A magnetic seat 222 is formed on the detecting unit 220, and receives a magnet 221. When the magnet 221 seated in the magnet seat 222 is adjacent to the magnetic switch M/S received in the magnetic switch holding part 236 provided on a sidewall of the support pieces 233, the magnetic switch M/S is closed by a magnetic force.

Meanwhile, when the detecting unit 220 is rotated by the continuous frictional force between the measuring wire 171 and the detecting unit 220, and the magnet 221 becomes distant from the magnetic switch M/S, the magnetic force applied to the magnetic switch M/S is offset, so the magnetic switch M/S is open.

The signal generated by the repeated opening and closing of the magnetic switch M/S is transmitted to the control unit 272 : Next, the control unit 272 reads the signal, and then the display 271 displays an output value which is preset according to the number of rotations, thus allowing a user to confirm a measured value.

As shown in FIG. 9, the detecting unit 220 is provided at its upper and lower portions with tension rollers 225. While the measuring wire 171 moves along the guide groove 223 of the detecting unit 220, the tension of the measuring wire 171 is controlled by the tension rollers 225. When the measuring wire 171 is not slipped from the detecting unit 220 by a frictional force between the measuring wire 171 and the detecting

unit 220, a length of the measuring wire 171 unwound from the bobbin is accurately detected by the detecting unit 220, and is transmitted to the control unit 272 in the form of an electric signal, and then is displayed on the display 271.

In the case where the detecting unit 220 is covered with the cover 300, the tension rollers 225 are unnecessary.

The battery holding plate 240 is positioned under the cover plate 230, and is fitted into the cover plate 230. The battery holding plate 240 has a guide hole 243, a plurality of battery holding holes 241, and PCB holding slots 242. In this case, the guide hole 243 is formed on the center of the battery holding plate 240. The guide pipe 238 for guiding the measuring wire 171 is inserted into the guide hole 243. The battery holding holes 241 are formed in such a way as to be equal to the numbers of the batteries B, and hold the batteries B in their places, in addition to the prevention of the unexpected movement of the batteries B. The PCBs for actuating the control unit 272 and the display 271 are stably and easily inserted into the PCB holding slots 242.

A plurality of batteries B are mounted to the measuring unit 200 for supplying electric power to the measuring unit 200. In this case, the shanks of the batteries are held by the battery holding holes 241 of the cover plate 240 while the terminals of the batteries B are inserted into a plurality of battery terminal holders 250. Further, the measuring unit 200 also has a holder support unit 260 for supporting the battery holders 250.

The battery terminal holders 250 are held by the single holder support unit 260.

Two bosses 262 are integrally formed on the inner surface of the holder support unit 260, and are held by the holding pins 273 integrally formed on the lower portion of the lower cap 270.

The process of measuring a depth of water using the device constructed in this way is as follows. First, the measuring unit 200 is thrown at a target place, and the

measuring weight 172 provided on the lower end of the measuring wire 171 passes through the measuring unit 200 and is stopped when reaching the bottom of the target place.

In this case, the measuring wire 171 passes over the guide groove 223 of the detecting unit 220 while generating a frictional force. While the detecting unit 220 is rotated by the frictional force, the magnetic switch M/S is repeatedly opened and closed by the interaction between the magnet 221 received in the detecting unit 220 and the magnetic switch M/S received in the magnetic switch holding part 236 provided at a surface of the support pieces 233. A signal generated by the repeated opening and closing of the magnetic switch M/S is transmitted to the control unit 272. The control unit 272 processes the signal prior to transmitting it to the display 271. The display 271 displays a measured value.

In this case, when the measuring weight 172 reaches the bottom of the target place and then the measuring wire 171 is stopped for a predetermined period of time, the display 271 displays a final measured value, that is, a depth of water based on the signal processed by the control unit 272, thus allowing a user to easily and correctly confirm the measured value.

Industrial Applicabilitv As described above, the present invention provides a portable device for measuring a depth of water, which can be thrown into a measuring place with only a simple manipulation without requiring additional equipments or a preliminary step, and which allows a user to easily read and confirm a measured value, thus being easy and convenient to use, and which is compact and is light in weight, thus being easy to carry and maintain. In addition, the portable device for measuring a depth of water of this

invention is capable of conveniently measuring a depth of water without requiring additional preliminary operations, such as assembling and transporting operations, thus being rapidly moved to a desired place, reducing a measuring time, and thus being efficient in terms of economy. Further, the portable device for measuring a depth of water of this invention is convenient to carry and use, thus easily measuring a depth of water while easily changing a position of a measured object as desired, therefore being utilized for various purposes, including fishing and aquatic sports, and is also applied to measure a length or a height of a building or a structure, etc., thus ensuring high marketability, meeting a variety of requirements of consumers, and accurately measuring the depth, height or length of a target according to various purposes.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.