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You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a non-provisional application based upon U.S. provisional patent application Ser. No. 60/579,743, entitled “PET DOOR”, filed Jun. 15, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a pet entrance door, and, more particularly, to an automated pet entrance door.  
         [0004]     2. Description of the Related Art  
         [0005]     Pet doors are known in the art, which include flexible flaps over an opening in a wall or door to allow a pet to have access to a house. The pet normally presses against the flexible flap allowing the pet to displace the flap and enter the house. The flap is non-insulated and can be very uneconomical during inclement weather. This sort of pet door offers little or no security, allowing other animals or even people to have access to the home.  
         [0006]     Pet doors available on the market today often consist of a soft plastic or aluminum material, which hang by gravity, typically in a swinging manner and are sealed by a magnetic device. Other doors have an overlapping of plastic material in such a way as to prevent excessive weather penetration. These sorts of pet doors operate by way of the pet having to push against the door or flap with its head in order to enter or exit.  
         [0007]     Automatic opening doors for pets are also known, which lock when closed to prevent unauthorized access into a home.  
         [0008]     What is needed in the art is a pet door that controls access yet reduces the amount of air that enters or exits the home.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention provides a pet door that both retracts based upon identification of the pet and provides a weather flap door.  
         [0010]     The invention comprises, in one form thereof, a pet door including a retracting exterior door revealing a passageway when open and an inner flexible door that covers the passageway.  
         [0011]     An advantage of the present invention is that the pet door is opened based upon the identification of an approaching animal and still maintains a weather resistant inner barrier to the weather until the pet overcomes the seal of the inner flexible door in order to enter the home.  
         [0012]     Another advantage of the present invention is that as soon as the pet is in, the inner door closes and the outer door closes, thereby creating an insulative space therebetween. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:  
         [0014]      FIG. 1  is a front view of an embodiment of the pet door of the present invention;  
         [0015]      FIG. 2  is a partially sectioned side view of the pet door of  FIG. 1 ;  
         [0016]      FIG. 3  illustrates, in a cross-sectional manner, a portion of the upper part of the pet door of  FIGS. 1 and 2 ;  
         [0017]      FIG. 4  is another view of  FIG. 3  with the door retracted; and  
         [0018]      FIG. 5  illustrates the installation of the pet door of  FIGS. 1-4  in a residential door.  
     
    
       [0019]     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     Referring now to the drawings, and, more particularly to  FIGS. 1 and 2  there is shown a pet door assembly  10  including an inner frame  12 , an outer frame  14 , a door assembly  16 , a control assembly  18 , a power source  20  and a door flap  22 . Inner frame  12  and outer frame  14  are mounted on opposite sides of a door or wall and extend beyond the opening therein. Inner frame  12  and outer frame  14  are fastened together through the intervening structure by way of screws or other fasteners.  
         [0021]     Door assembly  16  includes slats  24 , a roller tube  26 , a motor  28 , tracks  30 , and a brush seal  32 . Slats  24  are linked together in a rolling manner along the edges of each slat  24 . Slats  24  are interconnected yet are able to be wound around roller tube  26 . As shown in  FIGS. 3 and 4 , slats  24  have a cross sectional shape with a hollow interior defining a thermally insulative air gap. Motor  28  is connected to roller tube  26 , which supplies power for the rotation of roller tube  26  to thereby wind slats  24  therearound when door assembly  16  is in an open position. Tracks  30  on each side of frames  12  and  14  allow slats  24  to be retained in a substantially vertical manner as door assembly  16  moves slats  24 . A brush seal  32  is located along a proportion of outer door frame  14  to seal the mechanism of door assembly  16 , to thereby exclude insects and the of air therethrough.  
         [0022]     Control assembly  18  includes an operator interface panel allowing an operator to energize the control circuits of assembly  10  and to designate which transmitters  40  will function with assembly  10 . Control assembly  18  can also select the amount of time that door assembly  16  is in an open position and the proximity of transmitter  40  to which control assembly  18  should respond. Further, control assembly  18  can be utilized to establish a schedule as to when a transmitter  40  will or will not trigger the opening of door assembly  16  when transmitter  40  is proximate to door assembly  10 .  
         [0023]     Power source  20  includes batteries, which provide a DC power source to power motor  28  under the control of control assembly  18 . Additionally, an AC power source may be utilized to provide power to pet door assembly  10 .  
         [0024]     Flexible door flap  22  is positioned along one side of door assembly  16  to provide a further barrier for the movement of air through an opening in assembly  10 . When a pet wearing transmitter  40  approaches pet door assembly  10  and door assembly  16  is open, door flap  22  reduces the air movement through the opening until the pet passes through the opening. Door flap  22  may be removable.  
         [0025]     Transmitter  40  is worn on a pet, preferably on a pet collar, and provides an identification signal, in the form of a keyed transmission, which is detected by door assembly  10  and decoded by control assembly  18  to decide whether or not to open door assembly  16 , thereby providing a keyed entry system. A plurality of transmitters  40  may be utilized with control assembly  18  containing information as to which transmitters  40  are to effect the opening of door slats  24 .  
         [0026]     Assembly  10  can also be thought of as a security shutter  16  that automatically opens and closes when a pet approaches to allow access to an outside or an inside area. Soft flap  22  adds additional protection from the elements while shutter  16  remains open. Shutter  16  provides security, insulation and a weather-proof seal. Control assembly  18  includes circuitry, software and an operator interface, for optical, radio frequency or an RFID interface. The software is used to identify the Identification of the pet and to determine if and when to open and close shutter  16 .  
         [0027]     The activation of door assembly  10  is accomplished by way of transmitter  40  or an RFID added to a pet&#39;s existing collar. Assembly  10  receives a signal from transmitter  40  when the pet is within a preset range, typically 16-36 inches, and the door opens by the activation of motor  28 . Motor  28  causes roller tube  26  to rotate, onto which slatted door assembly  16  is wound and unwound. Door assembly  16  remains in an open position for up to five seconds after transmitter  40  is out of range. The user can adjust the range and timing of the door opening by way of control assembly  18 . Control assembly  18  may additionally include a battery life indicator.  
         [0028]     If transmitter  40  transmits an RF signal, a replaceable battery will be utilized to supply power to transmitter unit  40  on the pet&#39;s collar. Alternatively, RFID technology can be utilized to provide identity information relative to the particular pet approaching door assembly  10 .  
         [0029]     Software within control assembly  18  monitors the battery voltage and when the battery voltage drops to a certain level, the door will not activate to the rollup position. This safety feature prevents the door from remaining in an open position due to a low battery condition. The battery life indicator informs the user of the low battery condition. Additionally, a light curtain or IR screen will sense obstruction in the opening to prevent door assembly  16  from closing if an obstruction is in the opening. Additionally, if the door assembly should contact an item preventing complete closure of the door, the door assembly will reverse to the open position and sound an alarm until the obstruction is removed.  
         [0030]     Now, additionally referring to  FIGS. 3 and 4 , there is shown, in  FIG. 3 , a view of slats  24  in an extended closed position, and slats  24  are wound onto tube  26  when door assembly  16  is in an open position as shown in  FIG. 4 .  
         [0031]     Now, additionally referring to  FIG. 5  there is shown a view of door assembly  10  installed in a residential door  42 . The advantage of installing door assembly  10  in residential door  42  is that access on both sides of door  42  is normally maintained so that the pet can approach from either side without difficulty.  
         [0032]     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Summary:
A pet door including a retracting exterior door revealing a passageway when open and an inner flexible door that covers the passageway.