Abstract:
A material level indicator includes a probe, first and second signal compensating units, arranged at first and second ends of the probe respectively, and a controlling module arranged at the first end and includes a signal processor, a signal emitter, and a signal receiver. The second end is opposite to the first end. The signal processor is connected to the signal emitter and the signal receiver. The signal emitter emits an electromagnetic signal from the first end to the second end of the probe. The first and second signal compensating units reflect the electromagnetic signal, and the signal processor generates first and second time interval differences according to the reflected electromagnetic signal received by the signal receiver. The signal processor calibrates an environmental coefficient and indicates a dielectric coefficient of the material according to the first and second time interval differences respectively.

Description:
FIELD OF THE INVENTION 
     The technical field relates to indicators, more particularly to a material level indicator. 
     BACKGROUND OF THE INVENTION 
     Warehouse management is an important subject for storing and preserving materials. In a variety of industries such as the petrochemical industry, bulk food industry, feed industry, steel industry and cement industry, warehouses are used to store materials. The materials stored in warehouses include materials of different states including solids, liquids, and solid-liquid mixtures. For example, these materials are petroleum, coal, iron core, cement, corn, wheat, flour, butter and any other material. When different materials are stored in a warehouse, the temperature, humidity, and amount of stored materials in the warehouse will affect the expiration and preservation quality of the materials stored in the warehouse. For certain specific industries, explosions or other industrial accidents may occur if the temperature of the warehouse is not controlled properly. For instance, dry materials such as corns, soybeans, and conductive dust may lead to smoldering sparks or dust explosion due to temperature change. 
     However, most general material level indicators are just applicable for measuring a material level only and unable to detect environmental conditions and material conditions in a warehouse. 
     In view of the aforementioned drawbacks of the prior art, the discloser of this disclosure based on years of experience in the industry to conduct extensive researches and experiments and finally provided a feasible solution to overcome the drawbacks of the prior art effectively. 
     SUMMARY OF THE INVENTION 
     It is a primary objective of this disclosure to provide a material level indicator for measuring the material level in a container, and the material level indicator comprises a probe, a plurality of first signal compensating units, at least one second signal compensating unit and a controlling module. The probe includes a first end and a second end opposite to the first end; the first signal compensating unit is installed at the first end, and a first spacing distance is defined between two adjacent first signal compensating units; and the second signal compensating unit is installed at the second end. The controlling module is disposed at the first end and includes a signal processor, a signal emitter and a signal receiver, and the signal emitter is electrically coupled to the signal processor for generating an electromagnetic signal; and the signal receiver electrically is coupled to the signal processor. The electromagnetic signal generated by the signal emitter is transmitted through the first end to the second end, and the first signal compensating unit reflects the electromagnetic signal, and the signal receiver receives the electromagnetic signal reflected from the first signal compensating units and then transmits the electromagnetic signal to the signal processor to generate a first travel time difference, and the signal processor corrects an environmental coefficient according to the first travel time difference, and the second signal compensating unit reflects the electromagnetic signal, and the signal receiver receives the electromagnetic signal reflected by the second signal compensating units and transmits the electromagnetic signal to the signal processor to generate a second travel time difference, and the signal processor detects a dielectric coefficient of the material according to the second travel time difference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing the architecture of a material level indicator in accordance with a first preferred embodiment of this disclosure; 
         FIG. 2  is a schematic circuit block diagram of a controlling module in accordance with the first preferred embodiment of this disclosure; 
         FIG. 3  is a curve of first travel time difference versus first predetermined travel time difference; 
         FIGS. 4 a  to 4 d    are schematic views of a signal booster in accordance with this disclosure; 
         FIG. 5  is a curve of second travel time signals of a material level indicator without a signal booster and a material level indicator with a signal booster; 
         FIGS. 6 a  to 6 c    are schematic views of a weight of this disclosure; 
         FIG. 7  is a curve of noises of a material level indicator without a weight and a material level indicator with a weight; 
         FIG. 8  is a schematic view showing the architecture of a material level indicator in accordance with a second preferred embodiment of this disclosure; and 
         FIG. 9  is a schematic view showing the architecture of a material level indicator in accordance with a third preferred embodiment of this disclosure. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The technical contents of this disclosure will become apparent with the detailed description of preferred embodiments accompanied with the illustration of related drawings as follows. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
     With reference to  FIG. 1  for a schematic view showing the architecture of a material level indicator in accordance with the first preferred embodiment of this disclosure, the material level indicator is installed at the top of a container such as a bucket or a tank that contains a material and provided for detecting an environmental coefficient of the container, the height (or material level) of the material, and dielectric coefficient of the material. In  FIG. 1 , the material level indicator comprises an electrical box  10 , a probe  12  and a controlling module  14 . The electrical box  10  has a containing space  100 , and a through hole  104  formed at the bottom  102  of the electrical box  10  and communicated to the containing space  100 . 
     The probe  12  is installed at the bottom  102  of the electrical box  10  and extended in a predetermined direction D and includes a first end  120  and a second end  122  opposite to the first end  120 . The probe  12  is substantially a circular cylinder or a polygonal cylinder, and it may be an inflexible steel stick or may have a flexible wire. 
     The probe  12  has a plurality of first signal compensating units  16  disposed at the first end  120  of the probe  12 , and arranged equidistantly, and a first spacing distance d 1  is defined between two adjacent first signal compensating units  16 . In  FIG. 1 , the first signal compensating unit  16  is a recess formed at the first end  120  of the probe  12 . 
     The probe  12  has a plurality of second signal compensating units  18  disposed at the second end  122  of the probe  12  and arranged equidistantly, and a second spacing distance d 2  is defined between two adjacent second signal compensating units  18 , and the second spacing distance d 2  may be unequal to the first spacing distance d 1 . In  FIG. 1 , the second signal compensating unit  18  is a recess formed at the second end  120  of the probe  12 . 
     It is noteworthy that the first signal compensating unit  16  and the second compensating unit  18  as shown in  FIG. 1  are recesses, but they can also be protrusions or any other structures capable of reflecting the electromagnetic signal in other embodiments. In addition, the height and aperture of the recess of the first signal compensating unit  16  are not necessary to be equal to those of the second signal compensating unit  18 , and first signal compensating unit  16  and the second signal compensating unit  18  are connected in a predetermined direction D parallel to the probe  12 , or in a predetermined direction D not parallel to the probe  12 . Further, the first signal compensating unit  16  and the second signal compensating unit  18  may be circular fasteners sheathed on the probe  12  and the circular fastener is formed on the aforementioned recess. 
     The controlling module  14  is disposed in a containing space  100  and includes a circuit board  140 , a signal processor  142 , a signal emitter  144  and a signal receiver  146 . With reference to  FIG. 2  for a schematic circuit diagram of a controlling module  14  of this disclosure, the circuit board  140  may be a printed circuit board with copper circuits laid on both sides, and the signal processor  142 , the signal emitter  144  and the signal receiver  146  are installed on the circuit board  140 , and the signal processor  142  is electrically coupled to the signal emitter  144  and the signal receiver  146 . 
     In  FIG. 1 , the signal processor  142  is installed on one of the surfaces of the circuit board  140 , and the signal emitter  144  and the signal receiver  146  are installed on a surface of the circuit board  140  without the signal processor  142 , and an end of the probe  12  may be connected to a surface of the circuit board  140  having the signal emitter  144  and the signal receiver  146 . However, the signal processor  142 , the signal emitter  144  and the signal receiver  146  may be installed on the same surface of the circuit board  140  in another embodiment. 
     When the environmental coefficient is corrected and the dielectric coefficient of the material is detected in the container, the second end  122  of the probe  12  must be buried in the material, and the first end  120  may be exposed from the material or buried deeply in the material. 
     The signal emitter  144  for generating an electromagnetic signal may be a quartz oscillator. The electromagnetic signal generated by signal emitter  144  is transmitted along a surface of the probe  12 . When the electromagnetic signals are transmitted to the first signal compensating unit  16 , some of the electromagnetic signals are reflected by the first signal compensating unit  16  and transmitted to the signal processor  142  to generate a first travel time difference as shown in the curve  40  of  FIG. 3 . 
     It is noteworthy that the signal processor  142  includes a built-in counter for counting the count value of the electromagnetic signals generated by the signal emitter  144 , received by the signal receiver  146 , and reflected by the first signal compensating unit  16 , and then the signal processor  142  converts the count value into time by a Time Domain Reflectometry (TDR). In addition, the signal processor  142  further has a built-in first predetermined travel time difference as shown in the curve  30  of  FIG. 3 . This first predetermined travel time difference is generated after the electromagnetic signal is reflected by the first signal compensating unit  16  and transmitted to the signal processor  142  when the container has not contained the material. 
     When the container contains the material, the first travel time difference is greater than the first predetermined travel time difference since the material is attached to the probe  12  or the material produces steam, so that the signal processor  142  may compare the first travel time difference with the first predetermined travel time difference to correct the error (or the environmental coefficient) caused by a change of the environmental condition. 
     When the electromagnetic signals generated by the signal emitter  144  are transmitted along a surface of the probe  12  to the second signal compensating unit  18 , some of the electromagnetic signals are reflected by the second signal compensating unit  18  and transmitted to the signal processor  142  to generate a second travel time difference. When the second travel time difference is detected, the material has already been put into the container. 
     The signal processor  142  further builds in a second predetermined travel time difference, wherein the second predetermined travel time difference is generated by reflecting the electromagnetic signal by the second signal compensating unit  18  and transmitting the reflected electromagnetic signal to the signal processor when the material has not been put into the container. 
     When the material is put into the container, the second travel time difference is greater than the second predetermined travel time difference since the material is attached to the probe  12 , so that the signal processor  142  detects the dielectric coefficient of the material by comparing the second travel time difference with the second predetermined travel time difference. 
     Since the second signal compensating unit  18  is far away from the controlling module  14 , therefore the second signal compensating unit  18  reflects a signal generated by reflecting the electromagnetic signal by the second travel time difference, and such signal is weaker than that of the first travel time difference as shown in the curve  50  of  FIG. 5 . To effectively prevent the failure of transmitting the second travel time difference to the signal receiver  146 , the material level indicator includes a signal booster  19  as shown in  FIGS. 4 a  to 4 d   . The signal booster  19  is coupled to the second end  122  of probe  12  and capable of enhancing the signal intensity of the second travel time difference. Wherein, the curve  60  of  FIG. 5  shows that the material level indicator of the second travel time difference including the signal booster  19  has signal intensity significantly greater than the signal intensity of the second travel time difference excluding the signal booster  19 . 
     In  FIG. 4 a   , the signal booster  19  is substantially in a ring shape and coupled to the second end  122  of the probe  12 . In  FIG. 4 b   , the signal booster  19  includes a main body  190  and an extension  192 , and a side of the main body  190  is coupled to the probe  12 , and the main body  190  has an external diameter greater than the external diameter of the probe  12 . The extension  192  is coupled to a side of the main body  190  without the probe  12 , and the extension  192  has an external diameter decreasing in the direction extended towards the probe  12  (in order words, the external diameter of the extension  192  decreases with the distance away from the electrical box  10 ). In  FIG. 4 c   , the signal booster  19  is in the shape of a funnel, and its external diameter decreases with the distance away from the electrical box  10 . In  FIG. 4 d   , the signal booster  19  includes a cylinder  194  and a recess  196 , and the recess  196  is formed at an end of the cylinder  190  adjacent to the electrical box  10 ; and the cylinder  194  has an external diameter greater than the external diameter of the probe  12 , and the cylinder  194  is a circular cylinder or a polygonal cylinder. 
     Further, the second end  122  of the material level indicator selectively includes a weight  20  instead of the signal booster  19  as shown in  FIGS. 6 a  to 6 c    to reduce the noise of the second travel time difference. With reference to  FIG. 7  for a curve  70  of the detect signal of the material level indicator without the weight and a curve  80  of the detect signal of the material level indicator having the weight; and the weight  20  is coupled to the second end  122  of the probe  12 . In  FIG. 6 a   , the weight  20  is comprised of a plurality of ring members  200  and the ring members  200  are arranged equidistantly; wherein, the ring member  200  has an external diameter greater than the external diameter of the probe  12 . In  FIG. 6 b   , the weight  20  includes a connecting portion  202 , and an upper end  204  and lower end  206  disposed on two opposite sides of the connecting portion  202  respectively and coupled to the connecting portion  202 . The connecting portion  202  has an external diameter greater than the external diameter of the probe  12 ; the upper end  204  is coupled to the second end  122 , and the upper end  204  has an external diameter increasing with the distance away from the second end  122 ; the lower end  206  has an external diameter decreasing with the distance away from the connecting portion  202 . In  FIG. 6 c   , the weight  20  is in a conical shape and its external diameter increases with the distance away from the second end  122 . 
     With reference to  FIG. 8  for schematic view showing the architecture of a material level indicator in accordance with the second preferred embodiment of this disclosure, the material level indicator as shown in  FIG. 8  is substantially the same as that as shown in  FIG. 1 , except that each of the first signal compensating unit  16   a  and the second signal compensating unit  18   a  as shown in  FIG. 8  is an independent protrusion. When the probe  12  is a steel stick, the probe  12 , the first signal compensating unit  16   a  and the second signal compensating unit  18   a  are integrally formed. When the probe  12  is a wire, the first signal compensating unit  16   a  and the second signal compensating unit  18   a  are sheathed on a circular member of the probe  12 . In  FIG. 8 , the first signal compensating unit  16   a  has an external diameter equal to the external diameter of the second signal compensating unit  18   a.  However, the actual implementation is not limited to such arrangement only. The functions and related description of the material level indicator of this preferred embodiment are the same as those of the material level indicator of the first preferred embodiment, and thus will not be repeated. The material level indicator of this preferred embodiment at least achieves the same functions of the material level indicator of the first preferred embodiment. 
     With reference to  FIG. 9  for a schematic view showing the architecture of a material level indicator in accordance with the third preferred embodiment of this disclosure, the material level indicator as shown in  FIG. 9  is substantially the same as that as shown in  FIG. 8 , except that the material level indicator as shown in  FIG. 9  further comprises a connector  162   b  installed between two adjacent first signal compensating units  161   b  to provide an appearance of an I-shaped fastener  16   b,  and a connector  182   b  installed between two adjacent second signal compensating units  181   b  to form an I-shaped fastener  18   b.  The functions and related description of the material level indicator of this preferred embodiment are the same as those of the material level indicator of the first preferred embodiment, and thus will not be repeated. The material level indicator of this preferred embodiment at least achieves the same functions of the material level indicator of the first preferred embodiment. 
     While this disclosure has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of this disclosure set forth in the claims.