Patent Publication Number: US-2010127839-A1

Title: Method of operating radio frequency identification device and radio frequency identification system including radio frequency identification device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. nonprovisional patent application claims priority under 35 U.S.C. §119 to Korean Patent Application 10-2008-0117491, filed on Nov. 25, 2008, in the Korean Intellectual Property Office (KIPO), the entire contents of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Example embodiments relate to a method of operating a radio frequency identification device and a radio frequency identification system including the radio frequency identification device. 
     The Radio Frequency Identification (hereinafter, referred to as an RFID) is a non-contact identification system that exchanges information between the RFID device and the RFID tag using a radio frequency. The RFID device transmits modulation signals and continuous signals to the RFID tag. The modulation signals send data from the RFID device to the RFID tag, while the continuous signals receive response signals from the RFID tag. 
     When the RFID device transmits the modulation signals, the RFID tag receives the data transmitted through the modulation signals from the RFID device. When the RFID device transmits the continuous signals, the RFID tag generates response signals by adjusting the amplitude, phase, or frequency of continuous signals. The response signals are transmitted to the RFID device. 
     SUMMARY OF THE INVENTION 
     Example embodiments are directed to RFID device and system having an improved data storing efficiency. 
     Example embodiments provide an RFID system including one or more RFID tags and an RFID device for accessing the RFID tags. The RFID device compares a size of data to be stored in the RFID tags with a storage capacity of the RFID tags and divides the data based on compared results to write in the RFID tags. 
     According to an example embodiment, the RFID device may divide the data when the size of the data is larger than the storage capacity of the RFID tags. 
     According to an example embodiment, the RFID device may write the data in one RFID tag when the size of the data is less than the storage capacity of one of the RFID tags. 
     According to an example embodiment, the RFID device may write division information in the RFID tags, the division information indicating that the data is divided to be stored in the RFID tags. In addition, the division information may include the number of RFID tags in which the data is divided and written and information indicating which of the divided data is written. 
     According to an example embodiment, the RFID device may read the divided and written data from the RFID tags based on the division information. The RFID device may combine the read data based on the division information. Furthermore, the RFID device may read the divided and written data depending on a division sequence, store the read data in a buffer, and complete readout when all of the divided data are stored. 
     Example embodiments provide a method of operating an RFID device including dividing a data to be stored in one or more RFID tags and transmitting the divided data to the RFID tags so as to write the divided data in the RFID tags. 
     According to an example embodiment, the method may further include reading the written data from the one or more RFID tags and combining the read data to output as a read data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments will be more clearly understood from the following brief description taken in conjunction with the accompanying drawings.  FIGS. 1-7  represent non-limiting, example embodiments as described herein. 
         FIG. 1  is a block diagram illustrating an RFID system according to an example embodiment. 
         FIG. 2  is a flowchart explaining a writing operation of the RFID system of  FIG. 1 . 
         FIGS. 3 and 4  are diagrams illustrating the operation of the RFID system according to the flowchart of  FIG. 2 , respectively. 
         FIG. 5  is a flowchart explaining a reading operation of the RFID system of  FIG. 1 . 
         FIGS. 6 and 7  are diagrams illustrating the operation of the RFID system according to the flowchart of  FIG. 5 , respectively. 
     
    
    
     It should be noted that these Figures are intended to illustrate the general characteristics of methods, structure and/or materials utilized in certain example embodiments and to supplement the written description provided below. These drawings are not, however, to scale and may not precisely reflect the precise structural or performance characteristics of any given embodiment, and should not be interpreted as defining or limiting the range of values or properties encompassed by example embodiments. For example, the relative thicknesses and positioning of molecules, layers, regions and/or structural elements may be reduced or exaggerated for clarity. The use of similar or identical reference numbers in the various drawings is intended to indicate the presence of a similar or identical element or feature. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Example embodiments will now be described more fully with reference to the accompanying drawings, in which example embodiments are shown. Example embodiments may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those of ordinary skill in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Like reference numerals in the drawings denote like elements, and thus their description will be omitted. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Like numbers indicate like elements throughout. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms “first”, “second”, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of example embodiments. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural fowls as well, unless the context clearly indicates otherwise. It will be further understood that the teens “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of example embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle may have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of example embodiments. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly-used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     According to an example embodiment, an RFID system includes at least one RFID tag and an RFID device for accessing the RFID tag. The RFID device compares sizes of data to be stored in the RFID tag with the storage capacity of the RFID tag and divides the data based on compared results to store in at least one RFID tag. According to the example embodiment, a method of operating an RFID device includes dividing data to be stored in RFID tags and transmitting the divided data to the RFID tags so as to write in the RFID tags. 
     Hereinafter, example embodiments will be described in detail by explaining example embodiments with reference to the accompanying drawings. These example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
       FIG. 1  is a block diagram illustrating an RFID system  10  according to an example embodiment. Referring to  FIG. 1 , the RFID system  10  includes an RFID device  100  and an RFID tag  200 . 
     The RFID tag  200  receives transmission signals from the RFID device  100 . Moreover, the RFID tag  200  modulates continuous signals transmitted from the RFID device  100  and then generates response signals. The response signals are transmitted to the RFID device  100 . The transmission signals and continuous signals are transmitted to the RFID tag  200  by the RFID device  100 . The transmission signals are required for transmitting data to the RFID tag  200 . The continuous signals are required in order for the RFID tag  200  to generate the response signals. For example, the RFID device  100  is referred to as an RFID reader. However, the RFID device  100  is not limited to the RFID reader. The RFID device  100  may include many types of devices for accessing the RFID tag  200 . 
     The RFID device  100  includes a read/write controller  110 . The read/write controller  110  may control the operation in which the RFID device  100  reads the data stored in the RFID tag  200  and in which the RFID device  100  writes the data in the RFID tag  200 . For example, the read/write controller  110  may be a physically configured circuit. In another example, the read/write controller  110  may be software in the RFID device  100 . As another example, the read/write controller  110  may be configured such that some functions are carried out by the hardware and other functions are carried out by the software. For example, the RFID device  100  may communicate with the RFID tag  200  through an inductive coupling or a backscattering. 
     An RFID tag that performs more improved functions in addition to the function for storing only ID has been developed. An EPCGlobal (Electronic Product Code Global) has proposed, for example, an RFID tag (Class 2) having an extended memory storing capacity, an RFID tag (Class 3) including sensors and having Sleep mode and Wake mode, and an RFID tag (Class 4) including a network function capable of communicating with another RFID tag. 
     The RFID tag has a limited storage capacity due to the restriction of size and cost. Therefore, a new RFID system is required to effectively use the limited storage capacity of the RFID tag. The RFID device  100  according to the example embodiment divides data to store the data in the RFID tags and transmits the divided data to each of the RFID tags so as to write the divided data in the RFID tags, thereby effectively storing the data in the RFID tags. 
     The RFID system  10  and the RFID device  100  according to the example embodiment will be described more fully below with reference to  FIGS. 2 to 7 . 
       FIG. 2  is a flowchart illustrating a writing operation of the RFID system  10  of  FIG. 1 .  FIGS. 3 and 4  are diagrams illustrating the operation of the RFID system  10  according to the flowchart of  FIG. 2 . 
     Referring to  FIGS. 2 and 3 , the RFID device  100  detects a storage capacity of the RFID tag  200  in step S 110 . For example, the RFID device  100  may detect data with respect to the storage capacity of the RFID tag  200  while identifying the RFID tag  200  in order to detect an identifier ID of the RFID tag  200 . 
     In step S 120 , the RFID device  100  determines whether or not the storage capacity of the RFID tag  200  is less than the size of data DATA 1  to be stored in the RFID tag  200 . If the storage capacity of the RFID tag  200  is greater than the size of data DATA 1  to be stored in the RFID tag  200 , the process proceeds to step S 160 . 
     In step S 160 , the data DATA 1  is written in the RFID tag  200 . The data DATA 1  is transmitted to the RFID tag  200  through a transceiver  120  and an antenna  130 . The RFID tag  200  writes the data DATA 1 , which is transmitted through an antenna  230  and a transceiver  220 , and stored in a memory  210 . 
     Referring to  FIGS. 2 and 4 , assuming that the storage capacity of the RFID tag  200  is less than the size of data DATA 2  to be stored in the RFID tag  200 , that is, if the RFID device  100  determines that the storage capacity of the RFID tag  200  is less than the size of data DATA 2  to be stored in the RFID tag  200 , the process proceeds to step  5130 . 
     In step  5130 , RFID tags  200 , including antenna  230 , transceiver  220 , and memory  210 , and  300 , including antenna  330 , transceiver  320 , and memory  310 , are selected to store the data DATA 2 . The RFID device  100  may select the RFID tags  200  and  300  so that the total storage capacity of the RFID tags  200  and  300  is equal to or larger than the size of the data DATA 2  to be stored in the RFID tags  200  and  300 . For example, when the size of the data DATA 2  to be stored in the RFID tags  200  and  300  is 8 MB, the RFID tags  200  and  300  each having the storage capacity of 4 MB may be selected. The RFID tag  200  having the storage capacity of 6 MB and the RFID tag  300  having the storage capacity of 2 MB may also be selected. If the total storage capacity of the RFID tags  200  and  300  is equal to or larger than the size of the data DATA 2  to be stored in the RFID tags  200  and  300 , the RFID tags  200  and  300  may be selected regardless of the storage capacity of each RFID tag  200  and  300 . 
     In step S 140 , the RFID device  100  divides the data DATA 2  based on the storage capacity of the RFID tags  200  and  300 . For example, the RFID device  100  may divide the data DATA 2  into data DATA 2 _ 1  corresponding to the storage capacity of the RFID tag  200  and data DATA 2 _ 2  corresponding to the storage capacity of the RFID tag  300 . The RFID device  100  may generate division information DI to restore the data DATA 2  by grouping the data DATA 2 _ 1  and the data DATA 2 _ 2 . For example, the RFID device  100  may generate the data DATA 2 _ 1  and the data DATA 2 _ 2  by dividing the data DATA 2  into the first part and the latter part. 
     However, the RFID device  100  may generate the data DATA 2 _ 1  and the data DATA 2 _ 2  by dividing the data DATA 2  without being limited to the above-described method. Although the RFID device  100  generates the data DATA 2 _ 1  and the data DATA 2 _ 2  by dividing the data DATA 2 , example embodiments may be applicable to many types and forms of RFID devices that can group the data DATA 2 _ 1  and the data DATA 2 _ 2  and restore the data DATA 2  using the division information DI. 
     In step S 150 , the RFID device  100  writes the data DATA 2 _ 1  generated from the data DATA 2  in the RFID tag  200  and writes the data DATA 2 _ 2  generated from the data DATA 2  in the RFID tag  300 . Moreover, the RFID device  100  writes the division information DI in each of the RFID tags  200  and  300 . The division information DI indicates which of the data DATA 21  and DATA 2 _ 2  divided from the data DATA 2  is stored in each of the RFID tags. The division information DI may include the total number of data DATA 2 _ 1  and DATA 2 _ 2  divided and generated from the data DATA 2 , that is, the total number of RFID tags  200  and  300  in which the data DATA 2  may be stored. The division information DI may include information indicating which of the data DATA 2 _ 1  and DATA 2 _ 2  divided and generated from the data DATA 2  is stored in each of the RFID tags. 
     For example, the division information DI stored in the RFID tag  200  may include the total number of data DATA 2 _ 1  and DATA 2 _ 2  divided and generated from the data DATA 2 , for example, “2”. The division information DI stored in the RFID tag  200  may include information about whether or not the data DATA 2 _ 1  of the data DATA 2 _ 1  and DATA 2 _ 2  is stored, for example, “1”. That is, the division information DI stored in the RFID tag  200  may store “2-1” as a “data number-data sequence”. 
     For example, the division information DI stored in the RFID tag  300  may include the total number of data DATA 2 _ 1  and DATA 2 _ 2  divided and generated from the data DATA 2 , for example, “2”. The division information DI stored in the RFID tag  300  may include information about whether or not the data DATA 2 _ 2  of the data DATA 2 _ 1  and DATA 2 _ 2  is stored, for example, “2”. That is, the division information DI stored in the RFID tag  300  may store “2-2” as a “data number-data sequence”. 
       FIG. 5  is a flowchart illustrating a reading operation of the RFID system  10  of  FIG. 1 .  FIGS. 6 and 7  are diagrams illustrating the operation of the RFID system  10  according to the flowchart of  FIG. 5 . 
       FIGS. 5 and 6  illustrate an example embodiment of the reading operation of the RFID device  100  according to the example embodiment. In the example embodiment of the reading operation of the RFID device  100 , the data DATA 1  is stored in one RFID tag  200  as described with reference to  FIGS. 2 and 3 . 
     In step S 210 , the RFID device  100  accesses the division information DI of the RFID tag  200 . In step S 220 , the RFID device  100  determines whether or not the division information DI of the RFID tag  200  is set. As described with reference to  FIGS. 2 and 3 , if the data DATA 1  is stored one RFID tag  200 , the division information DI is not set. Therefore, the process proceeds to step S 270 . In step S 270 , the RFID device  100  reads the data DATA 1  stored in the RFID tag  200 . Since the data DATA 1  is stored in one RFID tag  200 , when the RFID device  100  reads the RFID tag  200 , the reading operation of the data DATA 1  may be completed. 
       FIGS. 5 and 7  illustrate another embodiment of the reading operation of the RFID device  100  according to the example embodiment. In the example embodiment of the reading operation of the RFID device  100 , the data DATA 2  is divided into the data DATA 2 _ 1  and the data DATA 2 _ 2  and the divided data DATA 2 _ 1  and DATA 2 _ 2  are stored in the RFID tags  200  and  300 , respectively, as described with reference to  FIGS. 2 and 4 . 
     In step S 210 , the RFID device  100  accesses the division information DI of the RFID tag  200 , the RFID tag  300 , or the RFID tags  200  and  300 . In step S 220 , the RFID device  100  determines whether or not the division information DI of the RFID tag  200 , the RFID tag  300 , or the RFID tags  200  and  300  is set. That is, the RFID device  100  may access the division information DI of the RFID tag locating within the communicable range. As described with reference to  FIGS. 2 and 4 , if each division information DI (for example, “2-1” and “2-2”) is set, the process proceeds to step S 230 . 
     In step S 230 , the RFID device  100  detects the RFID tags  200  and  300  in which the division information DI is set. Suppose that the RFID tag  200  is detected in steps S 210  and  5220 . The RFID tag  200  stores “2-1” as division information DI. That is, the division information DI of the RFID tag  200  indicates that one of two data DATA 2 _ 1  and DATA 2 _ 2  divided from the original data DATA 2  is stored in the RFID tag  200 . Accordingly, the RFID device  100  may detect the RFID tag  300  storing the data DATA 2 _ 2  of two data DATA 2 _ 1  and DATA 2 _ 2  divided from the original data DATA 2 . The RFID device  100  may detect the RFID tag  300  storing “2-2” as division information DI. 
     Similarly, the RFID device  100  may detect the RFID tag  200  using the division information DI in step  5230 , when the RFID device  100  accesses the division information DI, which is stored in the RFID tag  300 , in steps S 210  and S 220 . Step S 230  may be omitted when the RFID device  100  accesses the division information DI stored in the RFID tags  200  and  300  in steps S 210  and  5220 . 
     In step S 240 , the RFID device  100  determines the sequence of the data DATA 2 _ 1  and DATA 2 _ 2  stored in the RFID tags  200  and  300 . The RFID device  100  may determine the data DATA 2 _ 1  and DATA 2 _ 2  using the division information DI of each RFID tag. 
     As described above, the division information DI may include “data number data sequence”. The RFID tag  200  may store “2-1” as division information DI, and the RFID tag  300  may store “2-2” as division information DI. The RFID device  100  may determine the sequence of the data DATA 2 _ 1  and DATA 2 _ 2  stored in the RFID tags  200  and  300  using the division information DI of the RFID tags  200  and  300 . That is, the RFID device  100  may determine the data DATA 2 _ 1  stored in the RFID tag  200  as a first data and determine the data DATA 2 _ 2  stored in the RFID tag  300  as a second data. 
     In step S 250 , the RFID device  100  reads out sequentially the data DATA 2 _ 1  and DATA 2 _ 2  stored in the RFID tags  200  and  300 . The RFID device  100  reads the data DATA 2 _ 1  from the RFID tag  200  and then reads the data DATA 2 _ 2  from the RFID tag  300 . The data DATA 2 _ 1  and DATA 2 _ 2  read from the RFID tags  200  and  300  may be stored in a buffer (not shown) of the RFID device  100 . Since the data DATA 2 _ 1  and DATA 2 _ 2  are sequentially read from the RFID tags  200  and  300 , if the data DATA 2 _ 1  and DATA 2 _ 2  are stored, the data DATA 2  may be restored by grouping the read data in step S 260 . That is, the RFID device  100  divides sequentially the data DATA 2  into the data DATA 2 _ 1  and DATA 2 _ 2 , stores the data DATA 2 _ 1  and DATA 2 _ 2  in the RFID tags  200  and  300 , reads sequentially the data DATA 2 _ 1  and DATA 2 _ 2  stored in the RFID tags  200  and  300 , and restores the data DATA 2 . 
     The RFID device  100  may also store the data DATA 2 _ 1  and DATA 2 _ 2 , which are read from the RFID tags  200  and  300 , in the buffer and restore the data DATA 2  using the division information DI of the RFID tags  200  and  300 . If the division information DI includes the information about a method of generating the data DATA 2 _ 1  and DATA 2 _ 2  by dividing the data DATA 2 , the data DATA 2 _ 1  and DATA 2 _ 2  may have no need to be sequentially divided from the data DATA 2 . 
     According to the above-described example embodiment, the data DATA 2 _ 1  and DATA 2 _ 2  divided from the data DATA 2  are stored in the RFID tags  200  and  300 , respectively. However, the data may be stored in the RFID tags without being limited to the example described above. For example, the data to be stored in the RFID tags may be divided into any number of positive integers depending on the storage capacity of the RFID tags. 
     According to the example embodiments, the data DATA 1  having a size less than the storage capacity of the RFID tag  200  may be stored in the RFID tag  200 , while the data DATA 2  having a size larger than the storage capacity of the RFID tag  200  may be divided into the data DATA 2 _ 1  and DATA 2 _ 2  and stored in the RFID tag  300 . However, the data DATA 1  may be coded to reduce noises, the effect of channel, and the interference from other signals and may then be stored in the RFID tag  200 . In addition, the data DATA 2  may be divided into the data DATA 2 _ 1  and DATA 2 _ 2  and may be stored in the RFID tag  200  by coding the divided data to reduce noises, the effect of channel, and the interference from other signals. 
     Furthermore, the data DATA 1  may be coded to be stored in the RFID tag  200 , and the data DATA 2 _ 1  and DATA 2 _ 2  may be coded to be stored in the RFID tags  200  and  300 , respectively. 
     According to the example embodiments, when the size of the data DATA 1  to be stored in the RFID tag  200  is less than the storage capacity of the RFID tag  200 , the data DATA 1  may be stored in the RFID tag  200 , and the division information DI of the RFID tag  200  may not be set separately. However, when the data DATA 1  is stored in the RFID tag  200 , the data may set the information indicating that the data DATA 1  is not divided to be stored in the RFID tag  200 . 
     According to the example embodiments, the RFID device  100  may set the division information DI of the RFID tags  200  and  300  during the writing operation, but the RFID device  100  accesses the division information DI of the RFID tags  200  and  300  during the reading operation. That is, the storage area of the RFID tags  200  and  300 , which stores the division information DI, is known so that the RFID device  100  can access the tags. For example, a specific address of the RFID tags  200  and  300  may be known so as to store the division information DI. 
     According to the example embodiments, the division information DI may include “data number-data sequence”, but is not limited thereto. The division information DI may include the information (for example, data ID) about the data DATA 2  stored in the RFID tags  200  and  300 . 
     For example if the data DATA 2  is divided into the data DATA 2 _ 1  and DATA 2 _ 2  to be stored in the RFID tags  200  and  300 . The division information DI of the RFID tags  200  and  300  may include “data ID-data number-data sequence”. For example, the division information DI of the RFID tags  200  and  300  may include “DATA 2 ,  2 ,  1 ” and “DATA 2 ,  2 ,  2 ”. 
     For example if the data DATA 3  is divided into data DATA 3 _ 1  and DATA 3 _ 2  to be stored in other RFID tags (not shown). The division information DI of the RFID tags storing the data DATA 3 _ 1  and DATA 3 _ 2  may include “data ID-data number-data sequence”. For example, the division information DI of the RFID tags storing the data DATA 3 _ 1  and DATA 3 _ 2  may include “DATA 3 ,  2 ,  1 ” and “DATA 3 ,  2 ,  2 ”. 
     Different data may be stored in, for example, the RFID tag  200  storing the data DATA 2 _ 1 , the RFID tag storing the data DATA 3 _ 1 , the RFID tag  300  storing the data DATA 2 _ 2 , and the RFID tag storing the data DATA 3 _ 2  by adding the data ID to the division information DI. 
     The RFID system according to the example embodiments may include at least one RFID tag and an RFID device for accessing the RFID tag. The RFID device may compare a size of data to be stored in the RFID tag with a storage capacity of the RFID tag and divides the data based on compared results to write in the at least one RFID tag. Accordingly, the data storage efficiency of the RFID device and system may be improved. 
     Although example embodiments have been described in connection with the accompanying drawings, it is not limited thereto. It will be apparent to those skilled in the art that various substitutions, modifications and changes in form may be made therein without departing from the scope and spirit of the claims.