Abstract:
A drying scale is provided that contains a housing, a weighing system, a scale pan, a carriage, and a radiating source. The weighing system is disposed within the housing for weighing a sample, and a scale pan is operably supported by the weighing system and contains the sample to be weighed. The carriage moves between a loading position, and a radiating source is disposed within said carriage. The carriage exposes the scale pan when said carriage is in the loading position and moves the radiating source over at least part of the scale pan such that the radiates heat and dries the sample when the carriage is in the drying position. Also, the weighing system and the scale pan are fixedly disposed with respect to the housing, and the carriage and the radiating source move relative to the housing between the loading position and the drying position. In addition, a method performed by the drying scale is also provided.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a drying scale. More particularly, the present invention relates to a drying scale that contains a scale pan that is supported on a weighing system and that has a radiating source for heating and drying weighing material placed on the scale pan. In addition, the present invention relates to a method performed by the drying scale. The following disclosure is based on German Patent Application No. 19854563.0 which was filed on Nov. 26, 1998 and which is incorporated herein by reference. 
     2. Description of the Related Art 
     Examples of scales that contain a radiating source for drying samples to be weighed are generally described in U.S. Pat. No. 4,666,007 (“the &#39;007 patent”) and U.S. Pat. No. 4,889,201 (“the &#39;201 patent”). Both the &#39;007 patent and the &#39;201 patent are incorporated herein by reference. 
     As described in the &#39;007 patent, the drying scale is designed such that the radiating source does not obstruct the scale pan when a sample to be weighed is loaded on the scale pan. Specifically, the radiating source is arranged behind the scale pan, and after the sample is loaded onto the pan, a deflecting reflector is unfolded. Then, the thermal radiation produced by the radiation source is reflected via the deflecting reflector onto the scale pan to dry the sample. Afterwards, when the sample is dried, the deflecting reflector is folded away from the sample pan. Although the radiating source is located behind the scale pan so that it does not obstruct the scale pan, a large space exists between the radiating source and the scale pan. Thus, the thermal radiation generated by the source is weakened due to the distance that it must travel to the scale pan and due to reflection losses when it is deflected by the deflecting reflector. Accordingly, the energy efficiency of the drying scale described in the &#39;007 patent is not optimum. 
     An example of a drying scale that attempts to overcome the above problem is shown in U.S. Pat. No. 5,787,600 (“the &#39;600 patent”) which is incorporated herein by reference. As described in the patent, the drying scale contains a scale pan that is located directly below the radiating source when the sample in the pan is being dried. Also, when the sample is to be loaded onto the scale pan, the scale pan is moved out from underneath the radiating source. However, when the scale pan is moved with respect to the radiation source for the purposes of the loading the sample, the weighing system does not move. Thus, a complicated connection, which can be extended and retracted telescopically, between the scale pan and weighing system is required. However, such a complicated connection is extremely susceptible to vertical vibrations and degrades the accuracy of the drying scale. 
     To attempt to overcome such problem, the &#39;600 patent describes another embodiment in which both the weighing system and scale pan move from underneath the radiating source when a sample is to be loaded into the scale pan. However, such a design does not adequately overcome the above problem because, when the weighing system is moved out from underneath the radiating source, it is very sensitive to vibrations because it extends out from the drying scale. In addition, the various components used to guide the weighing system between the drying position and the loading positing must be extremely precise since the horizontal position of the weighing system must be exactly the same when it is in the drying and loading positions. Therefore, the complexity and cost of the drying scale is substantially increased. 
     SUMMARY OF THE INVENTION 
     One object of the present invention to provide a drying scale that has a weighing system that is not very sensitive to external vibrations and that can measure the weight of the sample with significantly increased accuracy. 
     Another object of the present invention to provide a method performed by a drying scale in which a weighing system of the drying scale is not very sensitive to external vibrations and can measure the weight of the sample with significantly increased accuracy. 
     A further object of the present invention is to provide a drying scale having relatively low complexity and cost. 
     A yet further object of the present invention is to provide a method performed by a drying scale having relatively low complexity and cost. 
     A still further object of the present invention is to provide a drying scale in which the energy efficiency of the drying scale is optimized. 
     An additional object of the present invention is to provide method performed by a drying scale in which the energy efficiency of the drying scale is optimized. 
     In order to achieve the above and other objects, a drying scale is provided. The drying scale comprises: a weighing system for weighing a sample; a scale pan that is operably supported by said weighing system and contains the sample to be weighed; and a radiating source that moves between a loading position and a drying position, wherein said radiating source exposes said scale pan when said radiating source is in said loading position and wherein said radiating source covers at least part of said scale pan to radiate heat and dry said sample when said radiating source is in said drying position. 
     In order to further achieve the above and other objects, a drying scale is provided. The drying scale comprises: a housing; a weighing system disposed within said housing for weighing a sample; a scale pan that is operably supported by said weighing system and contains the sample to be weighed; a carriage that moves between a loading position and a drying position; and a radiating source that is disposed within said carriage, wherein said carriage exposes said scale pan when said carriage is in said loading position, wherein said carriage moves said radiating source over at least part of said scale such that said radiation source radiates heat and dries said sample when said carriage is in said drying position, and wherein said weighing system and said scale pan are fixedly disposed with respect to said housing and said carriage and said radiating source move relative to said housing between said loading position and said drying position. 
     In order to even further achieve the above and other objects, a method for measuring a sample with a drying scale is provided. The method comprises: (a) placing a sample to be weighed in a scale pan that is operably supported by a weighing system; (b) moving a radiating source to a drying position over at least part of said sample in said scale pan; (c) radiating heat from said radiating source to said sample when said radiating source is in said drying position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which: 
     FIG. 1 shows a perspective view of a drying scale in a loading position in accordance with an illustrative embodiment of the present invention; 
     FIG. 2 shows a perspective view of the drying scale in a drying position in accordance with the illustrative embodiment of the present invention; 
     FIG. 3 shows a cross-sectional side view of the drying scale in the loading position in accordance with the illustrative embodiment of the present invention; and 
     FIG. 4 shows a cross-sectional side view of the drying scale in the drying position in accordance with the illustrative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments discloses specific configurations and components. However, the preferred embodiments are merely examples of the present invention, and thus, the specific features described below are merely used to more easily describe such embodiments and to provide an overall understanding of the present invention. Accordingly, one skilled in the art will readily recognize that the present invention is not limited to the specific embodiments described below. Furthermore, the descriptions of various configurations and components of the present invention that would have been known to one skilled in the art are omitted for the sake of clarity and brevity. 
     FIG. 1 is a perspective view of the drying scale in a loading position in accordance with an illustrative embodiment of the present invention, and FIG. 2 is a perspective view of the drying scale in a drying position in accordance with the illustrative embodiment. As shown in the figures, the drying scale comprises a housing  1 , a display  2 , operating keys  3 , an air level  4 , a printer  5 , a covering housing  6 , and ventilation openings  7 . Upon reading the specification, one skilled in the art will readily know the operations and functions of the display  2 , operating keys  3 , air level  4 , and printer  5 , and thus, such components are not described in extensive detail. 
     As further shown in FIG. 1, the drying scale contains a scale pan  9  which is exposed when the scale is in a loading position. In the loading position, an operator can measure a sample to be weighed, place it in the scale pan  9 , and monitor the display  2  to ensure that the proper amount of the sample is placed in the pan  9 . The scale pan  9  is located in a recessed portion of the housing  1  to protect the sample from drafts, and the walls of the recessed portion are lined with a sheet metal or plastic part  26  that can be removed for cleaning. 
     A radiating source  10  that provides thermal radiation for drying the sample is hidden below the covering housing  6  within a carriage  14 . The carriage contains (or is connected to) a carriage cover  24  and a front cover  8 . The carriage cover  24  contains ventilation openings  7 ′ and covers the top and sides of the radiating source  10  to prevent the operator of the scale from accidentally contacting the radiating source  10  and becoming burned. The carriage  14  can be moved horizontally between the loading position (FIGS. 1 and 3) and a drying position (FIGS.  2  and  4 ). When the carriage  14  is in the loading position, the carriage  14  and the radiating source  10  are retracted underneath the covering housing  6  to expose the scale pan  9 , and the operator can easily place a sample into the pan  9 . On the other hand, when the carriage  14  is moved to the drying position, the carriage  14  and radiating source  10  are placed over the scale pan  9 , and the radiation source  10  applies thermal radiation to the sample to dry it. Furthermore, when the carriage  14  and radiating source  10  are moved between the loading position and the drying position, the scale pan  9  and a weighing system  29  located below the pan  9  remain fixed with respect to the housing  1  and are not displaced. 
     Also, as shown in FIGS. 3 and 4, the carriage cover  24  and the front cover  8  are fastened together by lateral plates  25  and other connections that are not shown on the carriage  14 . Thus, the carriage cover  24  and front cover  8  both move together with the carriage  14 . In addition, most of the carriage cover  24  disappears below the covering housing  6  when the carriage  14  is moved to the loading position. (FIGS.  1  and  3 ). On the other hand, when the carriage  14  is moved to the drying position, the carriage cover  24  extends far from beneath the covering housing  6 . (FIGS.  2  and  4 ). 
     As best shown in FIGS. 2 to  4 , a viewing window  12  is located within the carriage cover  24  between the front cover  8  and the radiating source  10 . When the carriage  14  and radiating source  10  are in the drying position, a lower edge  22  of the viewing window  12  is placed on the top side of the housing  1 , and thus, the front portion of the scale pan  9  is sealed. Nonetheless, the sample within the scale pan  9  can be observed and monitored by the operator through the window  12 . On the other hand, as the carriage  14  and radiating source  10  are retracted from the drying position to the loading position shown in FIG. 1, the viewing window  12  is raised. As will be described in more detail below, the viewing window  12  quickly raises soon after the carriage  14  begins to retract from the drying position (FIG. 2) and remains raised as the carriage  14  fully retracts to the loading position (FIG.  1 ). Conversely, when the carriage  14  is moved from the loading position (FIG. 1) to the drying position (FIG.  2 ), the window  12  is not lowered until shortly before reaching the drying position. By raising and lowering the viewing window  12  in the above manner, the window  12  is prevented from contacting the upper portion of the sample on the scale pan  9  when the carriage  14  is retracted from the drying position to the loading position (or moved to the drying position from the loading position). As a result, the amount of the sample in the pan  9  is not disturbed, the measurement of the weight of the sample is more accurate, and the possibility that the sample becomes contaminated is decreased. 
     FIGS. 3 and 4 are cross-sectional side views of the illustrative embodiment of the present invention and show the structure of various components of the drying scale in more detail. Specifically, FIG. 3 shows the drying scale when the carriage  14  is in the loading position, and FIG. 4 shows the drying scale when the carriage  14  is in the drying position. 
     As indicated in the figures, the carriage  14  is supported within the housing  1  by two guide rails  15  that are fixed with respect to the housing  1 . Upper rollers  16  are rotatably connected to the carriage  14  and are disposed above the guide rails  15 , and lower rollers  17  are rotatably connected to the carriage  14  and are disposed below the guide rails  15 . Furthermore, although only one of the two guide rails  15  can be seen in FIGS. 3 and 4, the second guide rail  15  is disposed on the opposite side of the carriage  14  and supports the carriage  14  via upper and lower rollers  16  and  17  in a similar manner. 
     The carriage  14  is driven horizontally between the loading position and the drying position by a motor (not shown). The motor (not shown) is fixed with respect to the housing  1  and has a pinion (not shown) which engages two racks  18  that are secured to each side of the carriage  14 . In FIGS. 3 and 4, only one of the racks  18  is shown for the sake of clarity. As the motor (not shown) rotates, the pinion (not shown) engages the racks  18  and moves them laterally, and the carriage  14  moves laterally in response to the movement of the racks  18 . In addition, stoppers and end switches (not shown) are preferably provided in the drying scale to limit the lateral mobility of the carriage  14 . 
     As described above, the radiating source  10  is fastened on the carriage  14  such that it moves when the carriage  14  moves. In addition, the viewing window  12  is connected to the carriage  14  via two axles  19  and two levers  11 . As shown in FIGS. 3 and 4, the first axle  19  is connected to one side of the carriage  14 , and the first lever  11  is pivotably supported by the first axle  19 . Although not shown, the second lever  11  is connected to the opposite side of the carriage  14  via the second axle  19  in a similar manner. Furthermore, the window  12  is connected to the front edges of the two levers  11  such that the window  12  is pivotably supported by the first and second axles  19 . 
     The relative orientation between the levers  11  and the carriage  14  is determined based on the positions of first and second pins  20  within first and second guide grooves  21  disposed within the housing  1 . As shown in the figures, one end of the first pin  20  is connected to the first lever  11 , and the second end of the first pin  20  is disposed within the first guide groove  21 . Although not shown in the figures, the second lever  11 , second pin  20 , and second guide groove  21  are interconnected in a similar manner. As illustrated in FIG. 3, when the carriage  14  is in the loading position, the pins  20  are located in a rear portion of the guide grooves  21 . Accordingly, the levers  11  are pivoted around the axles  19  such that the viewing window  12  is raised to cover a front portion of the radiating source  10 . 
     Then, as the carriage  14  is moved towards the drying position shown in FIG. 4, the pins  20  travel forward through the guide grooves  21 . When the pins  20  travel through an initial portion of the grooves  21 , the levers  11  remain in a position such that the window  12  remains raised and continues to cover the front portion of the radiating source  10 . However, as the pins  20  travel further in the guide grooves  21  and almost reach the end of the grooves  21 , the pins  20  travel up oblique sections  21 ′ within the guide grooves  21 . As a result, the levers  11  are rotated clockwise around the axles  19 , and the viewing window  12  is lowered such that a buffer  13  located beneath the front edge  22  of the window  12  contacts the housing  1  (See FIGS.  2  and  4 ). (The portion of the housing  1  that contacts the buffer  3  is not shown in FIG. 4 for the sake of clarity). Based on the above configuration, the viewing window  12  is not lowered from its raised position to contact the housing  1  until it has passed over the scale pan  9 . Accordingly, the possibility that the window  12  will contact a sample placed in the scale pan  9  when the carriage  14  is moved to the drying position is extremely small. 
     The difference between the heights of the oblique sections  21 ′ of the guide grooves  21  and the remaining portions of the guide groove  21  is selected such that the viewing window  12  is raised sufficiently so that its lower edge  22  is located just below a lower edge  23  of the radiating source  10  (FIG.  3 ). With such a design, the viewing window  12  will not contact the sample when the carriage  14  moves back and forth between the loading position and drying position as long as the height of the sample within the scale pan  9  is less than or equal to a maximum permitted height. 
     However, if the operator fills the scale pan  9  with the sample such that the height is greater than the maximum height, the portion of the sample that extends above the maximum height will be pushed away by the lower edge  22  of the viewing window  12  when the carriage  14  moves to the drying position. In such a situation, a portion of the sample may adhere to the viewing window  12  and may possibly be pushed out of the scale pan  9 . Nonetheless, such operation prevents the more severe problem of the sample contacting the hot radiating source  10 , adhering to the source  10 , and possibly becoming carbonized. 
     As best shown in FIG. 3, the drying scale comprises a weighing system  29  that is disposed below the scale pan  9 . FIG. 4 illustrates the weighing system  29 , although it is partially hidden behind the carriage  14 . The weighing system  29  is fixedly disposed relative to the housing  1 , and thus, even when vibrations occur, the weighing system  29  does not vibrate with respect to the housing  1 . 
     In order to check and, if appropriate, readjust the sensitivity of the drying scale, a calibration weight, which is operably connected to the measuring sensor of the scale by motor or by hand, is typically installed. Such a calibration weight is preferably incorporated into the drying scale of the present embodiment. As shown in FIG. 3, a calibration weight  28  and the associated actuating mechanism  27  are incorporated into the weighing system  29 . However, for the sake of clarity, they are not illustrated in FIG.  4 . The configuration and operation of the actuating mechanism  27 , calibration weight  28 , and weighing system  29  will be readily known to one skilled in the art upon reading the specification, and thus, such description is omitted for the sake of brevity. 
     As described above in accordance with the illustrative embodiment of the present invention, a sample is loaded into the scale pan  9  by moving the radiating source  10  to a loading position. Afterwards, when the sample is to be dried, the radiating source  10  is moved from the loading position to a drying position over the sample. In other words, the scale pan  9  and weighing system  29  do not move with respect to the housing  1  when the radiating source moves between the loading and drying positions. As a result, the weighing system  29  it not very sensitive to external vibrations and can measure the weight of the sample with significantly increased accuracy. In addition, since the scale pan  9  and weighing system  29  are fixedly disposed with respect to the housing  1 , complicated components for precisely guiding the weighing system between a drying position and a loading positing are unnecessary. Thus, the complexity and cost of the drying scale is relatively low. 
     As further described above, the radiating source  10  is moved directly over the sample within the scale pan  9  when the sample is to be dried. Thus, the thermal radiation generated by the radiation source  10  does not need to travel a significant distance or be deflected to reach the sample. Accordingly, the energy efficiency of the drying scale is optimized. 
     The previous description of the preferred embodiments is provided to enable a person skilled in the art to make and use the present invention. Moreover, various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles and specific examples defined herein may be applied to other embodiments without the use of inventive faculty. For example, the specific components and configurations used to move the radiation source  10  between the loading position and the drying position and to raise and lower the viewing window  12  are clearly not limited to the components illustrated in the figures. Furthermore, one skilled in the art will readily recognize, upon reading the present application, that many different types of configurations can be used to move the radiation source  10  and window  12 . Therefore, the present invention is not intended to be limited to the embodiments described herein but is to be accorded the widest scope as defined by the limitations of the claims and equivalents thereof.