Dustproof structure for optical coordinate input apparatus

An optical coordinates input apparatus includes pairs of first light emitting elements and first light receiving elements, a plurality of pairs of second light emitting elements and second light receiving element having a light path intersecting a light path of the first light emitting elements and the first light receiving elements, and a filter section disposed on the front side of the light paths of the optical semiconductor elements for passing therethrough a light in the paths. The apparatus further includes a device from preventing a flow of an air containing dust from entering a space between the optical conductor elements and the filter section.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a coordinates input apparatus of an 
optical detection type which is attached on a front surface of a display 
unit for detecting a position of coordinates in a display surface thereof 
and for inputting the position of coordinates to a computer, and in 
particular, to a countermeasure for preventing dust. 
2. Description of the Prior Art 
Coordinates input apparatuses for manually inputting data of positions of 
coordinates to a computer are constructed in various types, for example, 
electromagnetic induction, electrostatic capacitance, transparent 
electrode, and optical detection types. Among these various types of 
coordinates input apparatuses, the optical detection type has attracted 
attention with respect to reliability and operability in which the 
apparatus is mounted on the front surface of a display unit and when an 
arbitrary position on the display surface of the display unit is pressed 
by a finger or the like to interrupt a path of light, the location of 
coordinates can be defined without directly touching a device detecting 
the coordinates position. (This type of apparatus is simply referred to as 
a coordinates input apparatus 12 herebelow). 
FIGS. 12-16 are diagrams illustrating the prior art coordinates input 
apparatus. FIG. 12 is a perspective view of the coordinates input 
apparatus mounted on the front surface of a display unit. FIG. 13 is a 
cross-sectional view illustrating the main portion on a light receiving 
side of the coordinates input apparatus. FIG. 14 is a schematic diagram of 
the rear side illustrating an internal structure of the coordinates input 
apparatus with the rear panel removed. 
In these diagrams, the coordinates input apparatus primarily comprises a 
frame 1 in a form of approximately a rectangle having an opening section 2 
at a central portion thereof, pairs of a plurality of light emitting 
elements 4 such as LED's and a plurality of light receiving elements 5 
such as phototransistors, the light emitting elements 4 and the light 
receiving elements 5 being disposed on the opposing edges, respectively on 
the rear side of the frame 1, namely, on the side opposite to a display 
surface 3a of a display unit 3 using a CRT or the like, and an 
arithmetic/operation unit 6 for detecting from the pairs of the light 
emitting elements 4 and the light receiving elements 5 a position where a 
light path 10 is interrupted and for inputting the position. 
The light emitting elements 4 and the light receiving elements 5 are 
fixedly mounted on a base plate 7 disposed in the frame 1 in such a 
fashion that a light emitting section 4a and a light receiving section 5a 
of each pair of the elements 4 and 5 oppose to each other; whereas on the 
front surface of a light receiving section 5a of the light receiving 
element 5, a light blocking plate 8 having light passing holes 8a with a 
predetermined area is so disposed that only an incident light from a light 
emitting element 4 paired with the light receiving element 5 can be 
received. Moreover, on the front side of the light blocking plate 8 and 
the light emitting elements 4, namely, in the peripheral portion of an 
operation area A, an infrared-ray filter 9 is mounted on the overall 
regions thereof to block the visual light. Consequently, an invisible 
light path 10 is formed by use of the ultrared-ray filter 9 in the 
operation area A on the front side of the display surface 3a. 
Next, a description will be given of the principle of an input operation of 
the coordinates input apparatus having above-mentioned configuration. For 
example, as shown in FIG. 12, if a finger 20 or the like touches a 
location on the display surface 3a to input the coordinates data thereof, 
the light path 10 associated with the location is blocked, which enables 
to define the position of the coordinates. That is, by sequentially 
causing light emission of the light emitting elements 4 to effect 
scanning, the blocked light path 10 in the x and y directions can be 
detected by use of the light receiving elements 5. The light path 10 is 
determined by the arithmetic/operation unit 6 and the position of the 
coordinates is transmitted to the host computer (not shown). 
As another prior art example, FIGS. 15-16 show an apparatus having a Video 
Display Terminal (VDT) filter disposed on the front side of a CRT display. 
FIG. 15 is a cross-sectional view of the primary section on the light 
receiving side, whereas FIG. 16 is a rear view illustrating the inner 
configuration thereof with the rear panel removed. 
The coordinates input apparatus primarily comprises a frame 1 in a form of 
approximately a rectangle having an opening section 2 at a central portion 
thereof, pairs of a plurality of light emitting elements 4 such as LED's 
and a plurality of light receiving elements 5 such as phototransistors, 
the light emitting elements 4 and the light receiving elements 5 being 
disposed on the opposing edges, respectively on the rear side of the frame 
1, namely, on the side opposite to a display surface 3a of a display unit 
3 using a CRT or the like, and an arithmetic/operation unit 6 for 
detecting from the pairs of the light emitting elements 4 and the light 
receiving elements 5 a position where a light path 10 is interrupted and 
for inputting the position of the coordinates to the host computer. Each 
terminal of the light emitting elements 4 and the light receiving elements 
5 is soldered on a base plate 7 disposed in the frame 1 in such a fashion 
that a light emitting section 4a and a light receiving section 5a of each 
pair of the optical semiconductor elements 4 and 5 oppose to each other. 
At the opening section 2, there is provided an operation panel 11 
comprising a VDT filter to enhance the visibleness of the display surface 
3a of the display unit 3 and to prevent dust from being attached to the 
display surface 3a. A light blocking plate 8 having light passing holes 8a 
with a predetermined area and a predetermined depth is disposed on the 
front side of the light receiving elements 5 arranged in a column form so 
that only an incident light from the associated light emitting element 4 
is received. Moreover, on the front side of the light blocking plate 8 and 
the light emitting elements 4, an infrared-ray filter 9 in a form of a 
rectangular frame is disposed in the entire periphery to block the visible 
light. Namely, the front side of the light receiving elements 5 arranged 
in a form similar to L and the front side of the light emitting elements 4 
arranged also in a form similar to L oppose to the respective outer 
surfaces of the infrared-ray filter 9 in an rectangular form; and an end 
section 9a of the filter 9 opposes to the periphery of the operation panel 
11. Consequently, on the front side of the operation panel 11, namely, on 
a side not opposing to the display surface 3a, an invisible light path 10 
is formed by use of the infraredray filter 9. 
For example, when a position of the operation panel 11 associated with an 
input position of the display surface 3a is pressed by a finger 12 to 
input the data of the position as shown in FIGS. 3 and 5, a light path 10 
passing through the pressed position 20 is blocked among the light paths 
formed along the surface of the operation panel 11. Consequently, by 
sequentially effecting light emission of the light emitting elements 4 to 
perform the scanning, the blocked light path 11 in the x and y directions 
can be detected by use of the light receiving elements 5. The blocked 
light path 10 is determined by the arithmetic/operation unit 6 and the 
position of the coordinates is outputted to the host computer (not shown). 
Such a conventional coordinates input apparatus is accompanied by a problem 
that dust in the air and dust fixed on the display surface 3a due to 
static electricity are drawn by an air flow indicated by an arrow mark in 
FIG. 13 to enter a space B between the infrared-ray filter 9 and the light 
receiving elements 5, namely, dust is likely to fix on the inner surface 
of the infrared-ray filter 9 and on the light receiving section 5a of the 
light receiving elements 5. This is also the case on the side of the light 
emitting elements 4, that is, dust is likely to attach on the light 
emitting section 4a. When dust fixes on the inner surface of the 
infrared-ray filter 9 and on the light receiving section 5a, the light 
transmittivity is considerably lowered, which may lead to a malfunction. 
Moreover, to prevent such a malfunction, the cleaning operation must be 
frequently conducted to remove the dust and the maintenance becomes 
complicated accordingly. Especially, an air flow is forcibly generated 
along the direction of the arrow mark as shown in FIG. 13 when a cooling 
fan is included in the display unit 3, which causes a considerable amount 
of dust to be fixed on the inner surface of the infrared-ray filter, the 
light emitting section 4a, the light receiving section 5a, and the like. 
In the prior art coordinates input apparatuses the infrared-ray filter 9 
formed with acryl resin or the like must be engaged with or fixed to the 
frame 1 formed with ABS resin or the like as shown in FIG. 13. Since the 
junction therebetween is exposed on the operation area A, the junction 
must be carefully conducted not to deteriorate the design of the 
apparatus, namely, stepped portions must not be formed and excessive 
adhesives must not be remained, which leads to a problem that the 
assembling operation becomes complex. Moreover, in such a conventional 
coordinates input apparatus, if an infrared-ray filter 9 formed with a 
hard material is designed to be tightly fixed to the operation panel 11 
and the display surface 3a, there arises a danger that the filter 9 is 
damaged because of a dimensional error or the like; and hence a slight 
space 13 is disposed between the end section 9a of the filter 9 and the 
opposing section thereof, namely, the peripheral sections of the operation 
panel 11 and the display surface 3a. As a result, the dust in the air or 
the dust fixed on the operation panel 11 or the display surface 3a due to 
static electricity are drawn by the air flow into the space A (FIG. 15) on 
the rear side of the infrared-ray filter 9. The dust is then fixed on the 
rear surface of the infrared-ray filter 9, the light emitting section 4a, 
the light receiving section 5a, and the like, and hence the light 
transimittivity is likely to be reduced and a malfunction is caused. As a 
further problem, the cleaning operation must be frequently conducted to 
remove the dust and thus the maintenance becomes complicated. 
The conventional optical coordinates input apparatus as described above 
cannot be adopted, particularly, as an apparatus to be borne on a vehicle. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a coordinates 
input apparatus which prevents dust adversely affecting the light 
transmittivity from being entered there and which solves the problems of 
the prior art techniques described above. 
Another object of the present invention is to provide a coordinates input 
apparatus which facilitates the assembling operation thereof and which 
solves the problems of the prior art techniques described above. 
The technical problems to be solved by the present invention includes 
above-mentioned objects. 
To achieve these objects, the present invention comprises the following 
means. 
(1) In an optical coordinates input apparatus having pairs of light 
emitting elements and light receiving elements corresponding thereto, a 
plurality of pairs of light emitting elements and light receiving 
elements, the light emitting elements having a light path which has an 
intersection with light paths of the light emitting elements and the light 
receiving elements corresponding thereto, and a filter section disposed in 
the light paths of these optical semiconductor elements to allow a light 
passing through the light paths to pass therethrough characterised in that 
a flow of air containing dust is prevented from entering a space between 
the optical semiconductor elements and the filter section. 
(2) In a coordinates input apparatus of the optical detection type having a 
plurality of optical semiconductor elements including light emitting 
elements and light receiving elements corresponding thereto and a filter 
disposed opposing to the optical semiconductor elements for blocking the 
visible light in which a light path is formed by use of the filter between 
the light emitting elements and the light receiving elements and on the 
front side of a display surface of a display unit and a position where the 
light path is blocked is detected so as to input a position of coordinates 
on the display surface characterised in that an airtight space is disposed 
between the filter and the optical semiconductor elements. 
(3) In a coordinates input apparatus of the optical detection type having a 
plurality of optical semiconductor elements including light emitting 
elements and light receiving elements corresponding thereto, a filter 
disposed opposing to the optical semiconductor elements for selectively 
passing the infrared light, and a frame disposed continuously with respect 
to the filter for covering the optical semiconductor elements in which a 
light path is formed by use of the filter between the light emitting 
elements and the light receiving elements and on the front side of a 
display surface of a display unit and a position where the light path is 
blocked is detected so as to input a position of coordinates on the 
display surface characterised in that the filter and the frame are formed 
as a composite unit from a material selectively passing the infrared light 
and that light blocking means is disposed to block an incident light from 
the frame section of the composite unit to the light receiving elements. 
(4) In a coordinates input apparatus of the optical detection type having a 
plurality of optical semiconductor elements including light emitting 
elements and light receiving elements corresponding thereto and a filter 
disposed opposing to the optical semiconductor elements for blocking the 
visible light in which a light path is formed by use of the filter between 
the light emitting elements and the light receiving elements and on the 
front side of a display surface of a display unit and a position where the 
light path is blocked is detected so as to input a position of coordinates 
on the display surface characterised in that a cushion member which is 
formed with a soft material and which has elasticity is disposed on an end 
section on the display surface side of the filter and that the cushion 
member is elastically brought into contact with a portion opposing the end 
section. 
The technical means described above operate as follows. 
According to the present invention, an airtight space is disposed so that 
air in the space external with respect to the airtight space is prevented 
from entering the space disposed between the visual light blocking filter 
and the optical semiconductor elements, thereby preventing the dust 
contained in the external air from entering the space. 
Moreover, according to the present invention, the filter and the frame are 
formed into a composite unit and hence a complex joining operation to join 
the filter and the frame is unnecessitated. An unnecessary infrared light 
that may enter due to the composite unit configuration can be interrupted 
by light blocking means such as a coating varnish and a light blocking 
holder; furthermore, the space defined between the visual light blocking 
filter such as an infrared-ray filter and a section opposing the end 
section of the filter, namely, the space between the filter and the 
peripheral sections of the operation panel and the display surface is 
stuffed with a cushion member such as sponge so as to prevent dust from 
entering the space, which enables to keep a satisfactory light 
transimittivity in any cases.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A description will be given of embodiments of the present invention with 
reference to the accompanying drawings. 
FIGS. 1-2 are schematic diagrams for explaining an embodiment of the 
present invention wherein FIG. 1 shows a cross-sectional view of the main 
section on the light emitting element side of the coordinates input 
apparatus and FIG. 2 is a perspective view of the infrared-ray filter of 
FIG. 1. In the embodiments to be described later, the same reference 
numerals will be assigned to the same components as those of the 
conventional example and explanation thereabout will be therefore omitted. 
In FIGS. 1-2, reference numeral 12 indicates an infrared-ray filter 
comprising a member molded with acryl resin approximately in a shape of a 
Japanese katakana, a filter section 12a, and a dust blocking wall 12b and 
functions to block the visible light so as to selectively pass the 
infrared ray. Opposing to the filter section 12a of the infrared-ray 
filter 12, there is provided a light emitting section 4a of a light 
emitting elements 4. An end of the dust blocking wall 12b attached to the 
inner side of the infrared-ray filter 12 is fixed on a base plate 7 on 
which the light emitting elements 4 are secured. Consequently, the light 
emitting elements 4 are so configured to be confined in an airtight space 
or room 13 defined by the infrared-ray filter 12 and the base plate 7. 
That is, the airtight space 13 containing a space C formed between the 
filter section 12a and the light emitting section 4a is separated from the 
space external with respect to the coordinates input apparatus, and hence 
an air flow generated by a cooling fan or the like as indicated by an 
arrow mark in FIG. 1 does not affect the air inside the airtight space 13. 
With the provision of the airtight space 13 defined as described above, 
the dust contained in the external air, for example, the dust in the air 
and the dust on the display surface 3a is prevented from being drawn by 
the air flow to enter a space C formed between the filter section 12a and 
the light emitting section 4a, which guarantees prevention of the dust 
from fixing to the inner surface of the filter section 12a and to the 
surface of the light emitting section 4a and hence enables to maintain a 
satisfactory light transimittivity under any conditions. Moreover, since 
the airtight space 13 can be implemented only by slightly modifying the 
shape of the infrared-ray filter utilized in the prior art apparatus, 
there does not arise a problem of increase in the production cost. 
Since the principle of the input operation of the embodiment is the same as 
the conventional example, the description thereabout will be omitted. The 
infrared-ray filter 12 may also be formed with other than the acryl resin, 
for example, vinyl chloride may be used. 
FIGS. 3-5 are explanatory diagrams for explaining another embodiment of the 
present invention wherein FIG. 3 shows a cross-sectional view of the main 
section on the light receiving element side of the coordinates input 
apparatus, FIG, 4 is a perspective view of the infrared-ray filter of FIG. 
3, and FIG. 5 is a perspective view of the light blocking holder of FIG. 
3. The same reference numerals are assigned to the same components as 
those of FIG. 1. 
In this embodiment, the infrared-ray filter 14 having a filter section 14a 
and a coupling section or an engaging section 14b is combined with a light 
blocking holder 15 including light receiving elements 5 for blocking a 
scattered light incident thereto, thereby implementing a countermeasure 
against the dust. Namely, with the front surface of the light blocking 
holder 15 closely fixed on the inner surface of the filter section 14a, a 
front section of the light blocking holder 15 is engaged with the coupling 
section 14b, which allows to define the airtight space 13 on the front 
side of the light receiving element 5 in the light blocking holder 15, and 
hence the air C between the filter 14a and the light receiving section 5a 
is confined in the airtight space 13, namely, the air C is separated from 
the external space. As a consequence, even if the dust contained in the 
external space is drawn by the air flow to enter the inside of the 
coordinates input apparatus, the dust cannot enter the space C between the 
filter section 14a and the light receiving section 5a, thereby maintaining 
the light transimittivity at a satisfactory level. 
Since the light blocking holder 15 of the embodiment includes a light 
passing hole 15a, the light blocking plate used in the conventional 
embodiment is unnecessitated. 
FIGS. 6-7 are diagrams for explaining still another embodiment of the 
present invention wherein FIG. 6 shows a cross-sectional view of the main 
section on the light receiving element side of the coordinates input 
apparatus and FIG. 7 depicts a perspective view of the inner configuration 
of the light blocking holder of FIG. 6. The same reference numerals are 
assigned to the same components as those of FIG. 3. 
In this embodiment, an infrared-ray filter 16 having a filter section 16a 
and a coupling section 16b is combined with a light blocking holder 17 
which comprises an upper section 17a and a lower section 17b and which can 
contain a plurality of light receiving elements arranged in a column, 
thereby implementing a countermeasure against the dust. When compared with 
the previous embodiment, this structure includes a reduced number of 
components. In this diagram, reference numeral 17c indicates a light 
passing hole, and the configuration of other sections not explained is 
basically the same as that of the previous embodiment. 
FIGS. 8-9 are diagrams illustrating another embodiment in which the filter 
and the frame are formed in a composite unit. 
In FIG. 8, reference numeral 18 denotes a molded body formed with vinyl 
chloride through a vacuum molding process and possesses a characteristic 
to block the visual light and to selectively pass the infrared ray. The 
composite unit 18 includes at an end thereof a filter section 18a, which 
opposes to the light receiving section 5a of the light receiving elements 
5 via a light blocking plate 8. The surfaces of the portion of the 
composite unit 18 not including the filter section 18a namely, the frame 
section 18b are coated with a coating varnish which includes a pigment 
such as carbon black and which blocks at least the infrared ray. 
Consequently, the filter section 18a functions in the same fashion as the 
infrared-ray filter of the prior art apparatus to pass only the infrared 
ray of the incident light from the light emitting element side, and the 
frame section 18b coated with the coating varnish 19 blocks the visible 
light and the infrared ray. As a result, only the infrared ray that has 
passed the filter section 18a reaches the light receiving section 5a of 
the light receiving elements 5. The provision of the composite mold body 
18 having the functions of the filter and the frame unnecessitates the 
complex operation to join the infrared-ray filter and the frame, which has 
been a problem in the prior art technique. And hence the operability of 
the assembling operation of the coordinates input apparatus can be greatly 
improved. 
The same mold 18 is disposed on the light emitting element side (not 
shown), The filter section 18a thereof opposes to the light emitting 
section of the light emitting elements, which are covered by the frame 
section 18b. However, the frame section 18b of the mold 18 disposed on the 
light emitting element side need not be necessarily coated with the 
coating material 19. Although vinyl chloride is used as the material for 
the mold 18 in the embodiment, another material selectively passing the 
infrared ray, for example, an acryl resin may also be used. The components 
and the input principle not particularly, described are the same as those 
of the conventional examples described above. 
FIG. 9 is a cross-sectional view of the main section on the light receiving 
element side of the coordinates input apparatus according to another 
embodiment of the present invention in which the same reference numerals 
are assigned to the same components as those of FIG. 8. In this 
embodiment, in place of the application of the coating material to the 
frame section 18b of the mold body 18, a light blocking holder 21 is 
provided which comprises an upper section and a lower section each formed 
with polyacetal. The light receiving elements 5 are contained in the light 
blocking holder 21. A light passing hole 21a is disposed in the front wall 
of the light blocking holder 21 so as to oppose to the filter section 18a 
of the mold body 18. Consequently, the infrared ray passing through the 
filter section 18a can reach the light receiving section 5a of the light 
receiving elements 5; however, the infrared-ray passing through the frame 
section 18b of the mold 18 is blocked by the wall surface of the light 
blocking holder 21 and thus cannot reach the light receiving section 5a, 
which guarantees the reliability like the preceding embodiments. 
In this embodiment, a protrusion 18c is formed on the inner surface of the 
filter section 18a of the mold 18 so that the front section of the light 
blocking holder 21 is engaged in a space defined by the protrusion 18c. 
Moreover, since the light passing hole 21a is formed in the light blocking 
holder 21, the light blocking plate 8 is unnecessitated. Furthermore, the 
material of the light blocking holder 21 is not limited to polyacethal, 
but any material that can block at least the infrared ray is applicable. 
FIGS. 10-11 are schematic diagrams depicting another embodiment in which a 
cushion member is used. 
In FIG. 10, an infrared-ray filter 9 disposed to oppose to the light 
receiving section 5a of the light receiving elements 5 via the light 
passing hole 8a of the light blocking plate 8 has an end section fixedly 
mounted on the frame 1, thereby defining the periphery of the opening 
section 2. Another end 9a of the infrared-ray filter 9 opposes to the 
peripheral section of the operation panel 11 and is provided with a 
cushion member 23 formed with a material like sponge, which is elastically 
brought into contact with the operation panel 11; consequently, the space 
22 is not connected to the space 22 formed between the infrared-ray filter 
9 and the light receiving elements 5. As a result, the dust existing on 
the side of the opening section 2 is blocked by the cushion member 23 and 
hence cannot enter the space D, namely, the prevention of dust from being 
attached to the inner surface of the infrared-ray filter 9 and to the 
light receiving section 5a can be guaranteed, which enables a satisfactory 
light transimittivity to be maintained in any situations. Since the cusion 
member 23 is not stiff, the infrared-ray filter 9 and the operation panel 
11 cannot be damaged by the cushion member 23; moreover, a low-priced 
cushion member can be easily incorporated in the apparatus. 
Although the embodiment has been described only with respect to the light 
receiving element side, the operations are also the same on the light 
emitting element side, namely, a cushion member 23 is buried in the end 
section 9a on the side of the operation panel 11 of the infrared-ray 
filter 9 opposing to the light emitting section so as to prevent the dust 
from entering the apparatus. 
FIG. 11 is a diagram illustrating a cross-sectional view of the main 
section on the light receiving element side of another embodiment using a 
cushion member 23 according to the present invention. This is an example 
of a coordinates input apparatus in which the input operation is conducted 
directly on the display surface or screen without using the operation 
panel. 
In the apparatus of this type as shown in FIG. 11, the end section 9a of 
the infrared-ray filter 9 opposes to the peripheral section of the displav 
surface 3a, and like in the previous embodiment, the cushion member 23 is 
buried in the end section 9a so that the cushion member 23 is elastically 
brought into contact with the display surface 3a, thereby preventing the 
dust from entering the space D defined between the infrared-ray filter 9 
and the light receiving elements 5. 
As described above, according to the present invention, the space defined 
between a filter such as an infrared-ray filter blocking the visible light 
and the optical semiconductor elements including light emitting elements 
or light receiving elements is sealed with an airtight space or room; 
consequently, the external dust is not allowed to enter the space and a 
satisfactory light transmittivity can be maintained in any cases, which 
prevents a malfunction due to the dust fixed to the apparatus and allows 
to improve the maintenance. 
Furthermore, according to the embodiment in which the filter and the frame 
are formed in a composite unit, since a mold body including the filter and 
the frame is used, the complex operation to join the filter and the frame 
is unnecessitated and the assembling operation is considerably improved; 
moreover, with the provision of the light blocking means such as the 
coating material and the light blocking holder, the reliability can be 
retained. 
According to the embodiment utilizing a cushion member, a cushion member is 
disposed on the end section of the visible light blocking filter such as 
an infrared-ray filter opposing to the light emitting elements and the 
light receiving elements, and the cushion member is stuffed between the 
end section and the opposing section so as to prevent the dust from 
entering the space therebetween. As a result, the dust is prevented from 
easily fixing to the inner surface of the visible light blocking filter 
and on the light emitting section of the light emitting elements and the 
light receiving section of the light receiving elements, which enables to 
keep a satisfactory light transimittivity under any conditions. 
While the present invention has been described with reference to the 
particular illustrative embodiments, it is not to be restricted by those 
embodiments but only by the appended claims. It is to be appreciated that 
those skilled in the art can change or modify the embodiments without 
departing from the scope and the spirit of the present invention.