Abstract:
Disclosed is a packaging system for housing a programmable thermostat. The thermostat is easily installed with a minimum of tools. The housing securely contains the electronic components and conveniently and attractively mounts upon the wall without exposed attachment means. A hinged door covers the control elements but controls remain accessable for deliberately setting the thermostat. The hinge has no loose parts and is established from elements carried on the door, the face plate and rear panel of the box like housing which encases the electronic components. The electronic components are held to the housing and the housing members attach to enclose the electronic components by press-engaging detent daggers. Finally, the packaging system allows for easy disassembly for access to the electronic components should repair be required.

Description:
BACKGROUND 
     Programmable thermostats allow for automatically changing the thermostat setting according to a variable and prearranged timetable. This allows increased energy efficiency in central heating and air conditioning at a minimal loss of comfort. 
     The present invention relates to the packaging or encasement of a programmable thermostat. A substantial marketing advantage is afforded programmable thermostat units that have the ability to replace existing thermostats and to thereby interface with a variety of currently installed systems. Further, it is preferred that the installation and assembly be simple enough that many homeowners can install the unit without employing a technician. The housing should be easily affixed to the wall and securely contain the electronic components. Also, the controls should be accessible, yet protected from idle tampering. Finally, the housing must be capable of economical manufacturing. 
     Each of these attributes is well served by the present invention. 
     SUMMARY OF THE INVENTION 
     The programmable thermostat of the present invention is assembled from six major pieces. The electronic components are on a circuit card and superposing keyboard and the housing is formed from a rear panel, face plate, door and window. The electronic components are best assembled at the factory, including the attachment of the keyboard which is mounted on spacers to separate it from underlying components. It is convenient to connect the keyboard to the card by screw means passing through the card and received into the spacers. 
     Installation of the programmable calculator begins with mounting the rear panel of the housing onto the wall. One set of apertures is provided in the back panel whereby screws pass through to anchor into the wall behind. Other apertures are provided in the back panel to allow the passage of wires from the heating or air conditioning system into the housing where they connect to the electronic components. The rear panel also carries snap receiving means and an integral portion of the hinge upon which the door will swing. 
     The face plate carries snap and alignment means whereby the circuit card and attached keyboard are connected to it. The face plate has apertures that allow access to manual switches, the keyboard, and display elements. The inside of the face plate also carries snaps which engage the rear panel upon assembly to enclose the electronic components, mounting them on the wall between the face plate and rear panel. 
     A hinged door is included in the housing to cover the keyboard and switches and it is arranged to be held in position by hinge elements carried by the front plate and rear panel. The door carries the rings of the hinges by which it is connected to the remainder of the housing. The pins are carried by either the face plate or back panel and collars are provided by both of these. The hinge is assembled when the face plate and rear panel are snapped together and collars seat on the ends of the pins to limit the axial freedom of the rings. 
     The arrangement of the present invention, discussed in greater detail below, provides an easy to install and assemble housing that has no exposed mounting means yet is easily disassembled for service. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of the packaging system of the present invention. 
     FIG. 2 is an elevational frontal view of the hinge connecting the door to the remainder of the housing of the present invention. 
     FIG. 3 is a cross sectional view of one hinge assembly taken along line 3--3 in FIG. 2. 
     FIG. 4 is an elevational frontal view of an assembly step in constructing a packaging system in accordance with the present invention. 
     FIG. 5 is an exploded perspective view illustrating the interconnection of a keyboard and circuit card, connected in accordance with the present invention. 
     FIG. 6 is a laterally viewed cross section of an assembled packaging system embodying the present invention. 
     FIG. 7 is a top view of a cross section taken along line 7--7 of FIG. 5 illustrating an attached keyboard and circuit card connected in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION 
     The packaging, assembly, and installation of the programmable thermostat in the present invention is based upon the interaction of six members, the electronic circuit card 12, keyboard 13, rear panel 11, face plate 14, door 15 and window 16. See FIG. 1. 
     The bulk of electronic components are built onto solid state card 12. Keyboard 13 is attached over some of these components by screws 20 which pass through holes 21 in card 12 to be threadedly received into spacers 26. Further, snaps, have detent daggers 27, seat and attach about digital display elements 23. The snaps aid in aligning spacers 26 with holes 21. Wires 24 connect the keyboard to the circuit board. 
     The circuit board and attached keyboard are snapped into face plate 14 which itself attaches to rear panel 11 during assembly to enclose the electronic components. In addition, the same operation which established the enclosure about the electronic components also secures door 15 about hinges 40 by securing rings 44 upon pins 45. 
     FIGS. 2, 3 and 4 show the assembly of hinge 40. FIG. 2 illustrates an assembled hinge with door 15 fully open. FIG. 3 best illustrates an assembled hinge by focusing on the cross section of one set of engaged hinge elements. This cross section is taken along line 3--3 of FIG. 2. 
     Rings 44 are formed of two parts, hooks 44A and 44B, each formed integrally with door 15. Splitting ring 44 into two opposing and axially displaced semicircular hooks, 44A and 44B, promotes easy plastic injection molding of a completely formed door with attached hinge elements. Assembled into a hinge, hook sections 44A and 44B encircle pin 45 in a pivotal engagement. Pins 45 protrude from pin blocks 46 which are here formed with face plate 14. Collar 47 is here carried on rear panel 11. The collar seats on the extended end of pin 45 to cooperate with pin block 46 in limiting the axial freedom of ring 44 on pin 45. This arrangement provides for attaching the hinged door without any tools and with no loose parts. Assembly operations are described further below. 
     Installation of a programmable thermostat packaged in the housing of this invention begins with mounting unassembled rear panel 11 onto the wall of the room. Wires leading to the central air conditioning and heating systems are brought into the housing through apertures in the back wall of the rear panel. If the four control wires (not shown) are bound where they exit the wall of the room, they are most easily brought through aperture 30; however, if separate, apertures 31 which align with terminals 25 are more convenient. Rear panel 11 is fastened to the wall with screws 33 passing through apertures 32 after the control wires have been brought through. 
     It is preferred that keyboard 13 be fastened to circuit card 12 at the factory presenting the person installing the unit with a completed electronic package which clips to the face plate. FIG. 7 shows a cross section of the assembled electronic package of FIG. 5. Detent daggers 27 engage display elements 23 to align the keyboard with the circuit card. Each detent dagger has a resilient arm 28 and engaging catch 29. The resilient arms allow the catches to clear the edges of the display elements during insertion and to spring into engagement upon full insertion. See FIG. 7. FIG. 5 shows screws 20 that pass through apertures 21 in circuit card 12 to threadingly engage spacers 26 and thereby secure the keyboard to the circuit card. 
     While it is preferred that the electronic package be assembled when sold, the ease herein provided is advantageous in the packaging sense in that it promotes inexpensive manufacture and easy disassembly should repair ever become necessary. 
     The assembled electronics package snaps into face plate 14. See FIG. 1. Guide 55 of keyboard 13 engages grooves 56 to align the keyboard with detent daggers 60. Pressing the electronic package further into face plate 14 forces resilient arms 61 of detent daggers 60 to yield until, when fully inserted, catches 62, which are biased by resilient arms 61, close behind the edge of the inserted keyboard. This secures the electronic package to the face plate. At this point, control wires presented through rear panel 11 are attached to terminals 25 of circuit card 12. 
     The apertures through face plate 14 provide access to elements of the electronic components. See FIG. 4. Apertures 84 and 85 allow switches to pass through the faceplate. Aperture 82 provides access to keyboard 13. Aperture 81 allows a view of display elements 23. In the assembled unit, hinged door 15 protects the switches and keyboard but does not cover the display elements. 
     The next step in installing and assembling the housing about the electronic components is to hang door 15 in preparation to assemble hinge 40. FIG. 4 illustrates the assembly stage of threading rings 44 carried on door 15 over pins 45 carried on face plate 14. Door 15 is closed against the face plate by pivoting it about these hinge elements after rings 44 are slid over pins 45 to meet pin blocks 46 which act as collars limiting the axial freedom of the rings in that direction. Rounded, non-locking detent snaps 50 of door 15 are received into recesses 51 of face plate 14 to hold the door closed. Closing the door holds rings 44 in place upon pins 45 until collars 47 seat upon the open ends of the pins to secure the rings upon the pins throughout all positions of door 15. 
     In this embodiment collars 47 are carried by rear panel 11 which is mounted to the wall of the building by screws 33. These collars are seated at the free ends of pins 45 at the same time the face plate 14 and the attached door 15 are connected to the rear panel. Face plate 14 carries detent daggers 71 which are received into slots 75. Detent daggers 71 have resilient arms 72 which allow catch 73 to pass retainers 76 in slots 75. The resilient arms bias the catches against the retainers to secure face plate 14 to rear panel 11. Thus pressing the face plate into engagement with the rear panel snaps the two together and encases the electronic components completing the hinge assembly. Air circulation to the sensing elements is provided by vents 35 in the rear panel. 
     Installation of window 16 completes packaging the electronic components and installation of that package upon the wall. The window carries detent snaps 52 to engage recesses 53 on face plate 14. The window is placed above that part of face plate 14 protected by door 15 and covers aperture 60 of the face plate through which display elements 23 are visible. 
     Finally, despite the internal connection means, disassembly is convenient should service ever be necessary. Slots 74 allows access to depress resilient arms 72 and left retainer 76 in order to disengage catch 73. This allows separation of face plate 14 from rear panel 11, but all the electronic components remain attached to the face plate. Slots 63 in face plate 14 allow access to resilient arms 28. Depressing arms 28 disengage catches 29 and allows removal of the electronic components from the face plate and presents the components for service. If necessary, keyboard 13 can be removed for additional access to circuit card 12. 
     Packaging the electronic components of a programmable thermostat in accordance with the present invention produces a unit that is capable of installation into a wide range of existing heating and air conditioning systems by homeowners of no particular technical expertise. A minimal number of parts, only six in the preferred embodiment, interconnect to support, house, and protect the electronic elements of the programmable thermostat. These parts are subject to easy and inexpensive manufacture in plastics by existing injection molding methods. 
     The parts interconnect to produce a unit that is easily installed with only a screwdriver and minimal use of that tool to prevent attendant risks of damage to electronic components. Further, the connecting means, except the hinges, are located inside the housing rather than as exterior attachment means, thus allowing simpler lines conducive to an aesthetically pleasing appearance. Despite the use of internal connectors, disassembly remains a simple procedure. 
     The door is hung on an exterior hinge assembled from members that are integrally formed on three different parts of the housing, the door, the faceplate, and the rear panel. No tools and no loose parts are required to assemble the hinge.