Abstract:
Dial face insert properly indexed or keyed so as to tightly fit into a correspondingly indexed or keyed housing. In a preferred embodiment, the dial face includes one or more reference scales printed thereon, such as a temperature scale. The housing to which it is indexed may be the gauge body, the gauge face or the gauge cover.

Description:
This application is a division of Ser. No. 09/067,527 Apr. 28, 1998 now U.S. Pat. No. 6,094,983. 
    
    
     BACKGROUND OF THE INVENTION 
     Gauges, such as pressure gauges, are commonly used in various technological fields for a variety of purposes, such as refrigeration, measuring force, measuring contents left in a cylinder, measuring water pressure, line pressure, etc. Such gauges generally include a pointer moveable relative to a calibrated dial. By way of example, refrigeration technology often requires the introduction of one or more refrigerants into apparatus. This procedure is somewhat dangerous, and requires pressure and temperature monitoring. Monitoring is usually accomplished with a manifold gauge assembly comprising a high pressure gauge and a low pressure gauge attached to a common manifold to allow for simultaneous high and low pressure monitoring. The gauges also include a temperature scale; each refrigerant having a particular pressure/temperature relationship. However, the particular temperature scales used on the gauge dials vary, and are a function of the identity of the refrigerant. For environmental reasons, recently there have been used a large number of different refrigerants, thereby requiring an equal number of temperature scales. However, the physical size of the gauge face usually prohibits or inhibits the provision of many multiple scales thereon. 
     Since it is impracticable and uneconomical to have a different gauge for each refrigerant, various methods have been contemplated for providing a single gauge adaptable to various refrigerants. For example, a universal scale can be used, with appropriate conversion factors available depending upon the particular refrigerant. However, this procedure is tedious and inconvenient, and requires that the operator always have available the appropriate conversion charts for the specific refrigerant being used. It is also prone to operator error. 
     U.S. Pat. No. 5,471,881 discloses a lenticular gauge face which incorporates multiple reference scales on a single standard manifold gauge face. Thus, a lenticular film is laminated over a gauge face image containing two different temperature scale images. Angling of the gauge allows viewing of one or the other of the distinct images. 
     U.S. Pat. No. 5,679,903 discloses a refrigerant monitoring set including a manometer and a transparent disk mountable on the outside of the windowed Lace of the manometer housing. The transparent disk includes at least one temperature dial for a given refrigerant which can be assigned to a pressure dial on the manometer face by means of zero-position alignment. 
     However, the foregoing solutions suffer from various drawbacks, including cost, difficulty in obtaining accurate readings, etc. Nor are these problems limited to gauges used in refrigeration. 
     It would therefore be desirable to provide a means for providing multiple reference scales on a single gauge or manifold without the concomitant problems of the prior art. 
     SUMMARY OF THE INVENTION 
     The problems of the prior art have been overcome by the present invention, which provides a dial face insert properly indexed or keyed so as to tightly fit into a correspondingly indexed or keyed housing. In a preferred embodiment, the dial face includes one or more reference scales printed thereon, such as a temperature scale. The housing to which it is indexed may be the gauge body, the gauge face or the gauge cover. 
     In another embodiment, the dial face bears indicia of time, and the housing is a watch. Thus, dial face can be removably inserted when the user enters a different time zone. Other embodiments include meters, such as electrical meters, where various scales are calibrated differently. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of one embodiment of a dial face in accordance with the present invention; 
     FIG. 2 is a top view of another embodiment of a dial face in accordance with the present invention; 
     FIG. 3A is an exploded perspective view of a gauge having the dial face of FIG. 1; 
     FIG. 3B is an exploded perspective view of a gauge having the dial face of FIG. 2; 
     FIG. 4A is an exploded perspective view of a threaded gauge having the dial face of FIG. 1; 
     FIG. 4B is an exploded perspective view of a threaded gauge having the dial face of FIG. 2; 
     FIG. 5A is an exploded perspective view of a first embodiment of a friction ring type gauge having the dial face of FIG. 1; 
     FIG. 5B is an exploded perspective view of a first embodiment of a friction ring type gauge having the dial face of FIG. 2; 
     FIG. 6A is an exploded perspective view of a second embodiment of a friction ring type gauge having the dial face of FIG. 1; 
     FIG. 6B is an exploded perspective view of a second embodiment of a friction ring type gauge having the dial face of FIG. 2; 
     FIG. 7 is a perspective view of the housing cover in accordance with a further embodiment of the present invention; and 
     FIG. 8 is a perspective view of the housing cover in accordance with a still further embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning first to FIGS. 1 and 2, there is shown a suitable dial face insert  10 , generally circular in configuration, preferably made of plastic. Those skilled in the art will appreciate that the particular configuration of the insert  10  need not be circular; it can be configured in any particular form to match the configuration of the device in which it is inserted. For purposes of illustration, generally circular gauges will be illustrated herein, although the invention is not to be so limited. 
     The type of plastic used is not particularly limited, although the insert  10  should be at least mostly transparent, allowing the user to see the indicator and/or optionally any other pertinent markers or information in the apparatus itself behind the insert  10 . In some instances it may be desirable that only the indicator be visible, and not the indicia on the dial face underneath the indicator, especially where visibility of the dial face would lead to confusion in reading the appropriate measurement from the insert. In such cases, the insert  10  can be partially or completely frosted or otherwise made partially or completely opaque. The insert  10  should be rigid enough to be stabilized in the apparatus once locked in place. Suitable materials of construction include polycarbonate, acrylic, acetate, Polyesters and other plastics. The insert  10  can be formed by any suitable method, such as stamping, cutting, molding, etc. The insert  10  has indicia printed, laminated, adhered or otherwise formed thereon, such as a temperature scale, a pressure scale, a time scale, etc. Preferably the indicia is circumferentially oriented with respect to the axis about which the indicator rotates, and is properly coordinated with the indicator so that when the insert  10  is locked in position, an accurate reading can be obtained. 
     In accordance with the present invention, the insert  10  is preferably planar or substantially planar and has an irregular perimeter. One or more protuberances or projections  5  are formed along the perimeter, forming corresponding recessed portions  6 . The projections  5  (and recessed portions  6 ) are irregularly spaced and are not all the same length, so that the insert  10  is keyed and can fit in the corresponding housing in only one position, as will be discussed in greater detail below. When in position, preferably the insert  10  is aligned with the existing dial face. 
     FIGS. 3A and 3B illustrate one embodiment of the present invention, where the insert  10  is detachably positioned in the case or housing of device  20 . Specifically, housing  20  has an outermost perimeter face  21  configured with recessed portions  5 ′ and projections  6 ′ respectively corresponding to projections  5  and recessed portions  6  formed on insert  10 . The insert  10  is appropriately positioned in the perimeter face  21  so that each projection  5  of the insert  10  sits in a recessed portion  5 ′ of the housing  20 , and each recessed portion  6  of the insert  10  accommodates a projection  6 ′ of the housing  20 . Insert  10  is secured in place by clear (preferably plastic) cover  30 , which is internally configured to lock onto the tabs  31  on housing  20  in a conventional manner well known to those skilled in the art. The projections  5  and recessed portions  6  of insert  10  (and corresponding recessed portions  5 ′ and projections  6 ′ of housing  20 ) are arranged such that the insert  10  can fit into the housing in only one position and is not rotatable. The indicia  25  appearing on insert  10  is appropriately located thereon with respect to the pointer or indicator  15  of the gauge, for example, such that calibration is proper when the insert  10  is properly located in the housing  20 . 
     FIGS. 4A and 4B illustrate another embodiment of the present invention, which is similar to the embodiments of FIGS. 3A and 3B except that the cover  30  is internally threaded, and detachably fits onto corresponding threads  35  in the housing  20  so as to secure the insert  10  in place. The recessed portions  5 ′ in the housing  20  ensure that the insert  10  is itself recessed below the outermost circumferential surface  21  of the face of the housing  20 , so that the insert  10  does not interfere with the capping operation of the device; for example, the position of the insert  10  is not altered upon placing the cover  30  onto the housing and locking it thereon, regardless of whether that locking operation involves a small twisting motion (the embodiment of FIGS.  3 A and  3 B), a threading operation (the embodiments of FIGS.  4 A and  4 B), a snapping operation (the embodiments of FIGS. 5A and 5B) or some other operation. 
     FIGS. 5A and 5B illustrate yet another embodiment of the present invention, which is similar to the embodiments of FIGS. 3A and 3B except that the cover  30  is configured to create a detachable friction fit over housing  20 . Thus, with insert  10  positioned in place in the housing  20 , the cover  30  together with lens  40  is frictionally engaged to the outer surface of the housing  20  in a “snap” type fit. Both the lens  40  and insert  10  have diameters larger than the inner diameter “d” of the outermost ring portion  31  of cover  30  so that they are properly secured by the ring portion  31  when the cover  30  locks in place. 
     FIGS. 6A and 6B illustrate a variation of the embodiment of FIGS. 5A and 5B. Specifically, the insert  10  is located within the housing  20 , rather than on the outermost surface of the face of the housing  20  as in FIGS. 5A and 5B. To that end, the outermost surface  21  of the housing  20  is regular and not notched, but rather the appropriate notching (recessed portions  5 ′ and projections  6 ′) is located just below the outermost surface  21  within the housing  20  as shown. For example, the dial face  60  may be cupped, so that the dial face itself forms the bottom of the cup, and has an extending annular side wall  61  that terminates by the outermost portion of the housing  20 . The top edge of the annular side wall  61  has the recessed portions  5 ′ and notches  6 ′ formed thereon as shown. Alternatively, the recessed portions  5 ′ and notches  6 ′ could be formed on an annular insert that is separate from the dial  60 . 
     In each of the embodiments, the cover  30  is removably attachable to the housing  20 , so that the insert  10  can be easily changed, depending upon the application (and the particular indicia desired thereon). 
     Those skilled in the art will appreciate that the notches corresponding to projections  5  and recessed portions  6  of insert  10  can be located in the cover  30  or the lens  40  rather the housing  20 . For example, FIG. 7 shows an internally threaded cover  30  having recessed portions  5 ′ and projections  6 ′ positioned in close proximity to the lens  40 . Similarly, FIG. 8 illustrates a cap  30  internally configured to lock onto tabs on the housing  20  as in the embodiment of FIGS. 3A and 3B, the cap  30  including recessed portions  5 ′ and projections  6 ′ in close proximity to the lens  40  for locating the insert  10 . 
     The flexibility of the present invention allows for more information to be readily available to the user than can be printed on a single dial face. It also allows for interchangeability so that many different types of indicia, such as indicator scales, can be used with a given device. Since each insert  10  is keyed to a specific housing, improper inserts cannot be mistakenly used.