Patent Publication Number: US-2002005019-A1

Title: Directional light for office spaces

Description:
CROSS REFERENCE TO RELATED APPLICATION  
     [0001] This application claims the benefit of U.S. Provisional Application No. 60/204,478, filed May 16, 2000. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] This invention relates to a directional light for indicating direction, and more particularly to a directional light for use in office spaces.  
       BACKGROUND OF THE INVENTION  
       [0003] Modern office environments are many times constructed from modular space dividing structures, for example, upright wall panels. The assignee of the present application, Haworth Inc., manufactures such wall panel systems. Examples of wall panels which are connected to form a wall panel system can be found in U.S. Pat. Nos. 3,990,204, 4,060,294, 4,199,206, 4,367,370, 5,377,466, 5,606,919, 5,806,258, 5,852,904, all of which are herein incorporated by reference.  
       [0004] Typically, wall panels are joined serially or at angled joints to divide a large space into smaller, individual work stations which are joined together by passages. These wall panel systems provide a more flexible alternative to multi-passage offices having conventional stud walls. Such wall panels can include other furniture components, and preferably include raceways that supply electricity throughout the work spaces and have electrical receptacles with standard three-prong electrical outlets.  
       [0005] The wall panels are configurable into a plurality of different layouts to meet the needs of the particular business, and can be reconfigured to alter the floor plan of the work spaces. When reconfiguring wall panels, the arrangement of work stations, passages and passage intersections as well as the location of electrical receptacles often change. For new employees and visitors who are unfamiliar with an office layout, difficulties may be encountered in locating an exit or meeting site. Difficulties also may be encountered after an office is reconfigured. Thus, there is a need in office environments to provide directions to direct people through these passages and intersections to desired locations, for example exits and conference rooms.  
       [0006] Illuminated signs are typically provided in commercial office buildings to identify the location of exits. Such lights are fixed to the wall or ceiling adjacent the exit with an illuminated directional arrow pointing toward the exit and with the word “exit” illuminated. The lights are hardwired to the building electrical system and thus, are not mobile. While these exit indicator lights are useful and are usually mandated by building codes, they perform the very specific function of indicating the location of an exit at a fixed location directly adjacent to a door. As a result, these signs provide little assistance in leading occupants through multiple passages to the exit.  
       [0007] Additional hardwired systems are known for directing occupants to an exit. These more complex systems have elongated indicator rails or cables which mount to building walls and start a significant distance from a door to lead an occupant to the door typically during emergencies. These systems, however, are not readily reconfigurable and have limited flexibility.  
       [0008] Lights that plug into standard electrical outlets are known, for example, night lights, personal safety lights and emergency lights. Examples can be found in U.S. Pat. Nos. 5,146,209 and 5,633,623. While these lights obviously provide light, they do not provide directional indicators to direct people to a specific destination, for example an exit or a specific room.  
       [0009] In view of the foregoing, it is an object of the present invention to provide a system of portable lights that is adaptable with multi-passage offices and modern office systems and provides direction indicators where needed in the office. It is a further object of the present invention to provide a directional light that is easily movable and has a direction indicator that is easily changed.  
       SUMMARY OF THE INVENTION  
       [0010] The present invention is directed to a directional light or indicator unit, which can plug into a conventional three-prong electrical outlet to power the light and has a housing with a front face that provides a directional indicator such as a lighted arrow. In use, a system of one or more of these directional lights are mounted to existing permanent walls or movable wall panels wherein the directional lights are placed, for example, along passageways or at passage intersections to direct an occupant to an exit door or other destination.  
       [0011] The direction of the indicator is easily selected so that the light is configurable to the specific office layout in which it is used. Further, the directional light preferably plugs into existing receptacles and therefore is readily portable. Accordingly, the directional light can be used in current offices without remodeling. That is, the business being conducted need not be interrupted by electricians using power tools to mount the directional light to a ceiling or wall or stringing new electrical wire through the office.  
       [0012] In one embodiment of the invention, each directional light can indicate a plurality of directions. The directional light has a user actuated switch that selectively energizes one or more lights which indicate a selected direction.  
       [0013] In another embodiment of the present invention, the directional light has windows or leg segments with associated lights arranged in a diamond pattern. The user selects the direction to be indicated and plugs the light into a conventional electrical outlet. The lights on a pair of adjacent windows are illuminated to create a direction indicating arrow. For example, the lights on the upper pair of windows of the diamond are illuminated to indicate straight ahead, or the lights on the left pair of windows of the diamond are illuminated to indicate a left direction, etc.  
       [0014] In another embodiment, the windows and lights are arranged in an X pattern. The direction is indicated, similar to the above embodiment, by selectively energizing the lights associated with an adjacent pair of windows or leg segments of the X pattern to define the resulting arrowhead which points in the desired direction.  
       [0015] In a further embodiment, the face of the light is rotatable and generally opaque except it has a translucent part in the shape of an arrowhead. The face is rotated so that the arrowhead points in the select direction. A light source within the plug-in light produces light that transmits through the translucent arrowhead to indicate the direction.  
       [0016] The directional light may have a backup power source that energizes the light when the main power goes out. Circuitry automatically switches to the backup power source when the main power goes out. Moreover, the circuitry may make the direction indicating lights flash when on backup power. 
     
    
    
     [0017] Other objects and purposes of the invention will be apparent to persons familiar with arrangements of this general type upon reading the following specification and inspecting the accompanying drawings.  
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018]FIG. 1 is a schematic plan view of an office environment with a system of directional lights according to the present invention;  
     [0019]FIG. 2 is a perspective view of a wall panel construction with a plurality of the directional lights according to the present invention;  
     [0020]FIG. 3 is an enlarged perspective view of a directional light on a wall panel;  
     [0021]FIG. 4 is a rear elevational view of the directional light;  
     [0022]FIG. 5 is a cross sectional view taken generally along line  5 - 5  in FIG. 4;  
     [0023]FIG. 6 is a diagram of the control structure for a directional light;  
     [0024]FIG. 7 is a control circuit diagram of the directional light;  
     [0025]FIG. 8 is a view similar to FIG. 3 but showing a first modified plug-in directional light;  
     [0026]FIG. 9 is a view similar to FIG. 3 but showing a second modified plug-in directional light; and  
     [0027]FIG. 10 is a view similar to FIG. 3 but showing a third modified plug-in directional light.  
     [0028] Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words “up”, “down”, “right” and “left” will refer to directions in the drawings to which reference is made. The words “in” and “out” will refer to directions toward and away from, respectively, the geometric center of the structure and designated parts thereof. Such terminology will include the words specifically mentioned, derivatives thereof, and words of similar meaning. 
    
    
     DETAILED DESCRIPTION  
     [0029] Referring to FIG. 1, there is schematically shown an office environment  20  that includes a plurality of space dividing structures, e.g. wall panels  21 . Generally, wall panels  21  divide the office environment  20  into hallways or passages  23 , hallway intersections  24  and work stations  25 . A doorway or other exit  27  is located at each opposite end of the illustrated office environment, which doorways  27  are formed through preexisting building walls  28 . A system of plug-in directional lights or indicator units  30  of the present invention is shown attached to some of the wall panels  21  and walls  28 . The lights  30  are positioned in the hallways  23  and at intersections  24  and serve to indicate the direction to a select destination to thereby provide directions to office occupants which may be employees or visitors. For example, the lights  30  can point to one doorway  27  which may be the nearest emergency exit doorway or an entry to a conference room.  
     [0030] More specifically, a multiple wall panel assembly  33  is shown in FIG. 2 and has two wall panels  21  serially joined together at junction  35  in end-to-end relation. Each wall panel  21  has one or more raceways  37  which may be a base raceway  38 A at the bottom thereof or a beltline raceway  38 B. A raceway  37  can also be positioned at the top of the wall panels depending on the type of wall panel appropriate for the office environment. Raceways  37  provide electrical power to outlets  39 , which are accessible through raceway covers  40  and are shown as three-prong, duplex outlets that allow two power plugs to be simultaneously inserted therein. As described herein, directional light  30  is inserted into an outlet  39  thereby mechanically supporting and electrically powering the light, here shown with a left direction indicator illuminated.  
     [0031] As shown in FIGS.  3 - 5 , a preferred directional light  30  has a generally square box-like housing  41  with a front wall  43  that is remote or spaced outwardly from the wall panel  21  when the light is plugged into an outlet  39  and a rear wall  45  that is adjacent the wall panel in opposing relation therewith. The front and rear walls  43  and  45  are both generally planar and essentially parallel to each other.  
     [0032] Side and top walls  47  and  48  are preferably integrally formed with the front wall  43 , for example molded from a plastic, to form a front housing cover  42  having a depth of about 0.75 inch and height and width of about 3.5 inches. Such compact dimensions and the light weight (less than about five pounds) of the directional light  30  allow it to be easily manually transported. A bottom wall  49  is integrally molded with the side and top walls  47  and  48  or is a cover attachable to the front cover  42 .  
     [0033] The front housing cover  42  thereby has a rearward-opening, rimmed tray-like shape. Fasteners  51  (FIG. 4) hold rear wall  45  on the front housing cover  42  to define a closed interior chamber  52  in which is mounted the associated electronics, which will be explained in greater detail below. Fasteners  51  have threads that are received in rearward-opening mounts or threaded bores formed integral with the front housing cover  42 .  
     [0034] To indicate directions, a plurality of direction indicators  54  are provided, specifically, four elongate indicator segments, here shown as light transmitting windows  53 A- 53 D, are arranged on the front wall  43  in the shape of a diamond and define the light transmitting areas for indicating directions. The windows  53 A- 53 D are through voids in the front wall  43 . Alternatively, the light transmitting windows  53 A- 53 D may be translucent portions of the front wall  43  with the remainder of the front wall  43  being opaque. The side and top walls  47  and  48  are also opaque.  
     [0035] In one embodiment of the invention, the bottom wall  49  is at least partially translucent so that the plug-in directional light  30  will illuminate downwardly toward the floor or an adjacent worksurface. Alternatively, the bottom wall  49  may be opaque so that the only light emanating from directional light  30  is through the windows  53 A- 53 D.  
     [0036] As best seen in FIGS. 4 and 5, the rear wall  45  includes an electrical power plug  55  which projects rearwardly and a recessed, indicator direction selection switch  57  which is rearwardly accessible. The power plug  55  has a disk-like base  61  to which is fixed a conventional three-prong arrangement of electrical power connecting pins  63 ,  64  and a ground pin  65 . Each pin  63 ,  64 ,  65  is connected to internal electronics via a separate conventional wire  66 . The pins  63 ,  64 ,  65  are adapted to be communally inserted into a conventional three-prong electrical outlet  39  to provide the electrical power to the directional light  30 .  
     [0037] With this plug arrangement, the directional light  30  can be removably mounted to any existing receptacle location to provide directions to an occupant. Thus, the directional light  30  can be located in a passage  23  or intersection  24  on the closest available receptacle outlet  39 . Further, the directional light  30  does not require any hardwired electrical connections, and the plug  55  additionally provides the mechanical support for the light when the plug is inserted into an outlet  39 . Accordingly, the preferred directional light  30  does not require separate mechanical fasteners, brackets or the like which greatly simplifies the structure of the directional light  30  and the process of mounting the directional light  30  to a wall.  
     [0038] Further, the base  61  is preferably rotatably mounted between the rear wall  45  and at least two inwardly extending finger-like mounts  67  with the pins  63 - 65  extending rearwardly through an aperture  69  in the rear wall. Mounts  67  are fixed to the rear wall, extend into the chamber  52  and then radially inwardly bend toward the center axis of the aperture  69 . Aperture  69  has a diameter less than base  61 . Accordingly, the base  61  is rotatably held between the rear wall  45  and mounts  67 , which allows the power plug  55  to be rotated to align with the outlet  39 . The directional light  30  can be aligned with the bottom wall  49  facing downwardly when the directional light  30  is mounted to any outlet regardless of the outlet&#39;s orientation.  
     [0039] Also, aperture  69  is offset to one side of the rear wall so that when directional light  30  is plugged into the duplex outlet  39  it does not cover both plug-ins. As such, the directional light  30  can be oriented on duplex outlet  39  so that the directional light does not prevent access to the other plug-ins in the outlet when mounted thereon.  
     [0040] The indicator direction selection switch  57  is mounted to the rear wall  45  laterally aligned with and spaced from aperture  69 . Switch  57  is accessible through the rear wall  45  and a user can select the directional light&#39;s indicated direction when directional light  30  is unplugged and removed from outlet  39 . In this unmounted state, the rear wall is accessible to permit a user to engage switch  57  and orient same to select the direction indicated by directional light  30 . When the directional light  30  is plugged into the outlet  39 , the switch  57  is closely adjacent outlet  39  and wall panel  21  and inaccessible to reduce the likelihood of accidentally changing the state of the switch  57 . It is understood that selection informing indicia may be placed on rear wall  45  adjacent switch  57  so that the selected direction is visually verifiable to the person moving switch  57  even though the direction indicators on the front of housing  41  are not energized.  
     [0041] Referring now to FIG. 6, the electrical system of the directional light  30  will now be described. This system has a principal power source  81 , which includes conventional AC line power from the electrical outlet  39  and rectifies the AC line power to DC power. A relay  83  receives the rectified power from the power source  81  and in its usual operating condition transmits same to switch  84 . A backup power source  86  is also connected to the relay  83 , and when principal power source  81  is interrupted, the relay transmits electrical power from the backup power source  86  to the switch  84 . Switch  84  selectively powers indicator lights  87  so that the lights indicate the select direction.  
     [0042] More specifically, a control circuit  90  that selectively powers the indicator lights is shown in FIG. 7. A rectifier  91  receives the line-in electrical power, e.g. a standard U.S. 120 volt, 60 hertz power signal, and rectifies same to a DC power signal. A resister  92  is serially connected to rectifier  91 . The node of resister  92  remote the rectifier is connected to capacitor  93 , zenier diode  94 , relay  95  and diode  96 . Capacitor  93  and zenier diode  94  are connected to ground in parallel. Resister  92  and capacitor  93  act as a low pass filter for the rectified DC power signal. Zenier diode  94  regulates DC voltage.  
     [0043] The DC power signal energizes the coil  97  of the relay  95 . The energized coil  97  connects the DC signal to the output of the relay  95 , i.e. holds the normally open terminal closed. In the alternative the relay can be solid state. The relay output is connected to switch  57  which includes a double pole, double throw switch  99 , which a user can position to select the two segments that indicate the select direction, and a nonshorting second switch  101 , which isolates nonadjacent segments from each other for any state of switch  57  by having a separate output for each of the four states of the indicator. More specifically, switch  101  prevents the light sources respectively associated with nonadjacent light transmitting windows  53 A and  53 C or windows  53 B and  53 D from being simultaneously energized.  
     [0044] A resister array  103  serially connects the outputs of isolating switch  101  to the light sources in the indicator  105 , and more specifically to selections of windows  53 A- 53 D. The resisters in the resister array control the current supplied to these light sources. Each light source in the illustrated embodiment has a plurality of serially connected light emitting diodes (LED)  107 , which in turn are connected to ground, that act as visual indicators when emitting light. The diodes  107  are aligned with the windows  53 A- 53 D so that the light they produce is transmitted from the interior chamber  52  of the housing  41  through the windows  53 A- 53 D.  
     [0045] The circuitry  90  selects and powers the light sources to indicate a direction using the line-in voltage. However, it is important to also indicate direction if the line-in voltage is interrupted, for example during a power failure in the building or an interruption of power service during a storm. The power could also be interrupted by a tripped circuit breaker or blown fuse if the circuit to which the directional light  30  is connected becomes overloaded. For this purpose, the circuitry  90  includes a battery  111  as a backup power source which powers the direction indicators, here LEDs  107 , when the line-in voltage is interrupted. The battery  111  is connected to a collector of transistor  113 . Transistor  113  acts as switch to control battery power to the LEDs  107 .  
     [0046] A timer  115  is connected to the battery  111  and the diode  96 . The timer  115  can be a conventional  555  integrated circuit timer, which triggers when the line-in voltage is interrupted. The timer  115  output is connected to the gate of transistor  113  to control the operation of transistor  111 , which supplies battery power to the relay  95  and LEDs  107 . The emitter of transistor  113  is connected to the normally closed terminal of the relay  95 . When the line-in voltage stops, the relay coil  97  is not energized and the normally closed terminal connects to the output terminal of the relay  95 . The battery now powers the LEDS through the switches  99 ,  101  as discussed above with regard to powering the LEDs with the line in voltage. In one embodiment, timer  115  is set to slowly intermittently open and actuate the transistor  113  so that the LEDs are intermittently powered and slowly blink.  
     [0047] The compact housing  41  and circuitry  90  provide a lightweight directional light  30  that is easily manually transportable and usable with any standard electrical outlet. The directional light  30  is mechanically supported on an outlet only by the plug  55  being received in the outlet  39 .  
     [0048] In use, a person takes one directional light  30  to a location where it is desired to indicate a direction and locates the nearest outlet  39 . The switch  57  is oriented to select the desired direction indicated by the indicators on the front of housing  41 . The plug  57  is oriented so that bottom wall  49  is down and one plug-in of a duplex outlet  39  is not covered. The power plug  55  is now inserted into the other plug-in of outlet  39  to support directional light  30  and energize select adjacent light indicator segments, e.g. segments  53 A,  53 D in FIG. 3. This installation process is repeated for other lights  30  in the office so that a pathway is indicated to the desired location by the directions indicated by directional lights  30 . The plug-in directional light  30  is thus easily configured to the office environment without the need for highly skilled laborers. Moreover, a plurality of lights  30  can be quickly installed in an office to indicate the select pathway through the office.  
     [0049] The pathway indicated by directional lights  30  can be easily changed simply by unplugging plugs  55  and turning switch  57  and reinserting plugs  55  into the same outlets  39 . It is also possible to reorient the directional lights  30  themselves or use directional lights  30  in a different office space. The directional lights  30  are manually unplugged, moved to new locations and simply installed as discussed herein.  
     [0050] While the above described embodiment of the present invention uses LEDs  107  as the light source for indicating a direction, other devices for indicating direction on an indicator unit  30  are also within the scope of the present invention. One example is the use of a liquid crystal display (LCD) to indicate direction. The indicator unit  30  employing an LCD to indicate direction would have switch  57  that a user could operate to select the direction by activating the LCD using an appropriate control circuit so that an adjacent pair of direction indicating segments of the LCD are activated in the manner as described above with regard to the LEDs  107  to indicate the select direction.  
     [0051] Additional light sources include low power, miniature light bulbs and electroluminescent technology. Examples of electroluminescent technology can be found in products produced by Metromark, Inc. of Minnetonka, Minn. Once again both of these light sources have appropriate circuitry connecting the power supply to the light source and switch  57  for selecting the indicated direction which is indicated by direction indicating segments.  
     [0052] It is also within the scope of the present invention to alter the layout of the light transmitting windows  53 A- 53 D and the associated light sources, e.g. LEDs  107 , as long as the new layout can indicate a direction to a destination. Referring to FIG. 8, there is shown a modified directional light  130 . Elements of the modified directional light  130  that are similar to elements described above are indicated by the same reference numerals with the prefix “1”.  
     [0053] The segments or windows  153 A- 153 D are arranged in an X pattern with window  153 A aligned with window  153 C and window  153 B aligned with window  153 D. The LEDs associated with adjacent apertures  153 A- 153 D are selectively illuminated as discussed above to indicate a direction. For example, the top adjacent windows  153 A,  153 B are illuminated to indicate a reverse or down direction, or the right windows  153 B,  153 C are illuminated to indicate a right direction, etc. This embodiment can also indicate a do not enter message by illuminating all windows  153 A- 153 D in the X pattern.  
     [0054]FIG. 9 shows a further modification of the above described embodiments of the inventive directional light  230 , in which elements that are the same as those in the first described embodiment above are indicated by the same reference numerals with the prefix “2”.  
     [0055] More specifically, the directional light  230  is enlarged so that it has direction indicators, here light transmitting windows  253 A- 253 D with associated light sources, e.g. LEDs, and an alpha-numeric indicator  260  which identifies the distance to the destination. The upper adjacent windows  253 A,  253 B are illuminated indicating a straight ahead direction. Indicator  260  is set to indicate the distance remaining to the indicated destination, e.g. an exit door. As shown, the directional light  230  indicates four yards (or meters) in a straight direction. The indicator  260  is set by a user accessing a control in the rear wall of the light  230 . The indicator  260  may be a single or double digit display device with each digit created by indicators. These digit indicators can be created by seven or sixteen segment displays or by a LED dot matrix display, all of which are connected to a driver circuit. Indicator  260  can also be an LCD or constructed with electroluminescent technology. It is also within the scope of the present invention to display other information by replacing the indicator  260  with additional windowed displays that are suitably driven by associated circuitry to display the desired information such as text messages. For example, the indicator  260  may identify the destination as “EXIT” or “CONFERENCE ROOM”.  
     [0056] Another embodiment of the invention is shown in FIG. 10, wherein elements that are the same as those in the first described embodiment are referenced by the same reference numerals with the prefix “3”.  
     [0057] Directional light  330  has housing  341  with an opaque front wall  343 . A direction indicating face  346  is rotatably mounted centrally to front wall  343 . Face  346  has two directional indicating segments, have light transmitting windows  353 B and  353 C, which define a single direction indicator  354  and can be apertures in the face or transparent portions with the remainder of the face being opaque, forming a direction indicating arrowhead. The windows  353 B and  353 C on face  346  as shown in solid line indicate right. When it is desired to indicate a different direction, face  346  is rotated to another position with the direction indicator  359  indicating the desired direction. An example of another possible position of windows  353 B,  353 C is shown in broken line and indicates left. While the direction indicator  354  is defined by segments or windows  353 B or  353 C, the direction indicator  354  may also be a single three-sided triangle or other shape which is generally recognized as a pointer to indicate a direction.  
     [0058] The face  346  and front wall  343  may have cooperating structure to hold the windows  353 B,  353 C in the selected direction and yield upon application of a force to the face. One structure for holding the face in the select direction is a set screw operating between the face  346  and front wall  343 , with the set screw loosened the face can turn relative to the front wall and with the set screw tightened the face can not rotate. Another structure for holding the face  346  relative to the front wall  343  is a cooperating protrusion and receiving recess structure that engages in each of the positions of the face, e.g. up, down, right and left. Such a protrusion and recess structure would yield upon application of a manual force so the face would be adjusted to the desired direction. Another structure for holding the face relative to the front wall is a friction engagement between the face and front wall that holds the face on the front wall yet allows the face to rotate when a force, usually a manual force, is applied thereto. Moreover, directional light  330  with the rotating face  346  can indicate any direction in its 360 degree rotation.  
     [0059] In operation, a system of directional lights  30  are provided wherein the directional lights  30  can be inserted into outlets  39  to indicate direction as discussed herein. The lights  30  are plugged into conventional outlets  39  and thus can be retrofitted to preexisting offices which include wall panels  21  and fixed walls  28 . It will be understood that while wall panels  21  are disclosed herein to subdivide an office space, the wall panels  21  alternatively may be fixed walls, such as stud walls which define a similar arrangement of passages  23  and intersections  24  as illustrated in FIG. 1.  
     [0060] A plurality of directional lights  30  thereby defines a direction indicating light system usable in combination with space-dividing walls. Moreover, the directions indicated by directional lights  30  can be changed if the destination changes. For example, the lights  30  can be used to indicate the desired pathway through the wall panels  21  of a divided office space. If the wall panel configuration or destination is changed, the lights  30  are easily reconfigured to indicate a new pathway. The directional lights  30  can be moved to new outlets and/or the directions indicated by the light can be changed simply by adjusting switch  57 . For example, if the positions of the wall panels changes, then the pathways and intersections will change. There is a need to indicate desired travel pathways to a destination in this new wall panel configuration. Each directional light  30  is set to indicate a direction from a receptacle  29  to the destination by positioning switch  57  and is then plugged into the receptacle. This procedure thereby will indicate the pathway from the position of select directional light  30  to the destination.  
     [0061] Additionally, the indicator units  30  may be further modified. For example, the indicators on the indicator units  30  may be symbols other than arrows. Further, while the indicators are lighted in the illustrated embodiments, the indicators may be nonilluminated.  
     [0062] As discussed herein, the indicator units  30  preferably use visual indicators, it also may be desirable to use audible indicators either alone or in combination with the visual indicators.  
     [0063] It also is within the scope of the invention to use different color indicators to form different systems of indicator units  30  which are used simultaneously in the same office area. For example, a plurality of indicator units  30  having green indicator lights might be used to identify an exit, while orange indicator units  30  are used in the same passages to identify a conference room. Each indicator unit  30  could have a preset color or could have multiple colors wherein the color is adjusted or set during installation.  
     [0064] Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.