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CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application comprises an improvement on application Ser. No. 615,339, filed May 30, 1984, U.S. Pat. No. 4,638,433, in which the inventor is Wayne R. Schindler assigned to the assignee of the present application.This application is a continuation of application Ser. No.  08 / 700 , 610  filed Aug.  12 ,  1996 , now U.S. Pat. No. Re.  36 , 703 , which is a continuation of application Ser. No.  08 / 425 , 724  filed Apr.  20 ,  1995 , now U.S. Pat. No. Re.  35 , 364 , Oct.  29 ,  1996 , which is a continuation of Ser. No.  08 / 087 , 142 , Jul.  2 ,  1993 , abandoned, which is a continuation of Ser. No.  07 / 715 , 006 , Jun.  13 ,  1991 , abandoned, which is a continuation of Ser. No.  07 / 398 , 379 , Aug.  24 ,  1989 , abandoned, which is a reissue application of U.S. Pat. No.  4 , 750 , 118 , which is a continuation- in - part of application Ser. No.  06 / 615 , 339  filed May  30 ,  1984 , now U.S. Pat. No.  4 , 638 , 433 .   
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to garage door operators and in particular to a novel garage door operator wherein the receiver can be energized by two or more transmitted codes which are stored in the receiver. 
     2. Description of the Prior Art 
     Garage door operators of the prior art used transmitters in which the code can be changed by various methods as, for example, by moving two position switches to change the code. Such systems have also used code changing switches in the receiver so that the receivers can be set to correspond to the selected transmitter code. 
     It has also been known to use fixed frequency transmitters and fixed frequency receivers such that if the transmitted frequency matches the receiver frequency the receiver will respond. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a plurality of transmitters wherein each transmitter has its own unique and permanent non-user changeable code and wherein the receiver can be placed into a program mode wherein it will receive and store two or more codes corresponding to two different transmitters. The number of codes which can be stored in transmitters can be extremely high as, for example, greater than one million codes. Thus, the invention makes it possible to eliminate the requirements for code selection switches in the transmitters. 
     In the present invention the decoder module in the receiver will be capable of learning several different transmitted codes which will eliminate code switches in the receiver and also provides for multiple transmitters for actuating the garage opener. 
     The communication link can be various system such as radio frequency, light, wires, etc. 
     The invention makes it very easy for the user to operate the system and more secured code systems are available due to the higher number of available codes. 
     An encoded signal will be utilized wherein a pulse and blank time comprises a sync time base and different link pulses such as 1, 2, 3 or 4 milliseconds can be selected so as to provide different codings. Each datum can be 1, 2, 3 or 4 times the length of the sync pulse. The timing is from the rising edge to rising edges of the pulse and with ten data bits the number of codes can be in excess of one million codes. 
     In the invention, each transmitter encoder will contain a chip which contains a unique code and the receives will be able to memorize two or more as, for example, five different transmitter codes. This eliminates the need to have coding switches in either the transmitter or receiver. This eliminates the requirement that the user set the code switches so they match since the code switches are eliminated. 
     In the invention, during an operate mode, a receiver code must match an already programmed code four times in order to operate the garage door. This match is referred to as a valid code. Each valid code can be separated by up to two error codes and still have the output indicated as accurate. 
     In the program mode a code must be received four times in a row in order to be permanently stored in the receiver. Any error code will reset the valid code counter. 
     The advantage of the coding scheme are: 
     1. Higher peak power without exceeding the FCC rules which gives longer transmitter range. 
     2. Eliminate code switches in the transmitter and receiver making it easier for a customer to install and operate his garage door operator. 
     3. Customers having more than one transmitter will not have to match codes. 
     4. More secure codes due to the higher number of combinations which are available. Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure and in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a prespective view illustrating a garage door operator; 
     FIG. 2 illustrates in block form the invention; 
     FIG. 3 comprises a flow diagram; 
     FIG. 4 is a continuation of the flow diagram; and 
     FIG. 5 illustrates the coding scheme. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a garage door operator  10  mounted to the ceiling of a garage and connected to operate a door  17 . Garage door operator  10  has a head unit  11  which is supported from the ceiling which includes a motor which drives a suitable chain to which a trolley  13  is attached so that it moves along a rail  12 . The trolley  13  has a release cord  20  and pivotally carries a lever arm  14  which is attached to a bracket  16  mounted to the door so as to raise and open it by pulling it along conventional rails. 
     The header unit  11  includes a receiver and operating mechanism and can be actuated from a control unit  38  which has a operate switch  39 . 
     The garage door operator can also be operated by the transmitters  26  and  28  which have operate transmit buttons  27  and  29 , respectively. 
     As illustrated in FIG. 2 the garage door operator includes a receiver  41  which has a suitable antenna  42  for receiving radio frequency transmissions from the transmitters  26  and  28  and supplies an input to a decoder  43  which provides an output to a microprocessor unit  44 . The microprocessor unit  44  is connected to a garage door operator mechanism  46  which includes the motor which drives the chain  15  to move the door  17  in a conventional manner. The control  38  is connected to the microprocessor  44 . A pair of switches  22  and  23  are mounted on a switch unit  19  connected to the unit  11  and also to the microprocessor  44 . The switch  22  is a two position switch that can be moved between the operate and program positions to establish the “operate” and “program” modes. The switch  23  can be moved to a number of selected positions indicated by the  1  through  5  so as to allow the particular code of a number of different transmitters to be stored in the receiver so that the receiver will respond to such codes. 
     In the illustrated embodiment, the receiving unit can respond to up to five different transmitters which have five different transmitting codes. FIG. 5 illustrates the code utilized in which the bit times are nominally 0.5 milliseconds for example. The data times are nominally 1, 2, 3 or 4 milliseconds. 
     The sync pulse is a unit measure of time. Each datum is measured with respect to the sync pulse and each datum can be 1, 2, 3 or 4 times the length of the sync pulse. The timing is from the rising edge to rising edge of adjacent pulses. Using 10 data bits the number of codes which is available is in excess of one million codes. 
     In the invention, each transmitter such as transmitters  26  and  28  will have a unique code which is determined by the encoder chip contained in the transmitter. The receiver unit will be able to memorize and store a number of different codes as, for example, five different transmitter codes which eliminates the need of coding switches in either the transmitter or receiver which are used in the prior art. This also eliminates the requirement that the user match the transmitter and receiver code switches. 
     When the garage door operator is initially installed, the switch  22  is moved to the program mode and the energize button  27  of the first transmitter  26  is depressed so that the unique code of the transmitter  26  is transmitted. This is received by the receiver  41  and decoded by the decoder  43  and supplied to the microprocessor unit  44 . The switch  23  is placed in the first position and with the switch  22  in the program mode the code of the transmitter  26  will be supplied to the memory address storage  47  and stored therein. Then if the switch  22  is moved to the operate mode and the transmitter  26  energized by depressing the transmit switch  27 , the receiver  41 , decoder and the microprocessor  44  will compare the received code with the code of the transmitter  26  stored in the first memory location in the memory address storage  47  and since the stored memory address for the transmitter  26  coincides with the transmitted code of the transmitter  26  the microprocessor  44  will energize the garage door operation mechanism  46  to open or close the door. 
     In order to store the code of the second transmitter  28  the switch  22  is moved again to the program mode and the switch  23  to the second position and the transmitter  28  is energized by depressing its transmit switch  29 . This causes the receiver  41  and decoder  43  to decode the transmitted signal and supply it to the microprocessor  44  which then supplies the coded signal of the transmitter  28  to the memory address storage  47  where it is stored in a second address storage location. Then the switch  22  is moved to the operate position and when either of the transmitters  26  and  28  are energized, the receiver  41  decoder  43  and microprocessor  44  will energize the garage door operation mechanism  46  to cause the door to either move up or down depending upon its initial position. Thus, the codes of the transmitters  26  and  28  are transmitted and stored in the memory address storage  47  during the program mode after which the garage door operation mechanism will respond to either of the transmitters  26  and  28 . Any desired number of transmitters can be programmed to operate the garage door mechanism as, for example, up to five transmitters can be programmed into the memory address storage  47  by using the program switch  22  and the selector switch  23 . 
     This invention eliminates the requirement that binary switches be set in the transmitter or receiver as is done in systems of the prior art to establish a code to which the receiver will respond and the invention also allows a garage door operator to respond to a number of different transmitters because the specific codes of a number of the transmitters is stored and retained in the memory address storage  47  of this unit. 
     FIGS. 3 and 4 comprise the flow chart which describe both the operate and program modes of the invention. Basically, in the operate mode, a received code must match a program which has already been programmed and for four times so as to operate the garage door. This match is referred to as a valid code in the flow chart. Each valid code can be separated by up to two error codes and still have the output actuate. For example, a code of valid-error-error-valid-valid-valid would actuate the door. On the other hand, a code of valid-valid-valid-error-error-error-valid would not actuate the door. 
     In the program mode a code must be received four times in a row in order to be permanently stored. Any error code will reset the valid code counter. 
     With reference to the flow diagrams of FIGS. 3 and 4 if it be assumed initially that the switch  22  is in the operate position an incoming signal will be supplied to terminal A in FIG.  3  and an output will be supplied to terminal B which indicates that the switch  22  is not in the program mode but in the operate mode Terminal B is illustrated in FIG.  4  and the microprocessor compares the incoming code with any codes in the five code locations stored in the memory address storage  47 . If these codes match then the error counter is cleared and all other valid counters. If the valid counter receives the code four times than  then output is supplied to the terminal C which operates the garage door operator. If the valid counter for the code equals less than 4, then the valid code counter is incremented until the valid code counter does equal 4 which actuates the proper output. Relative to FIG. 4 if the input code does not match any of the five stored codes, then the error counter is incremented and when the error counter equals 3 the error counter is cleared and all valid counters are cleared. 
     If the switch  22  is in the program mode as shown in FIG. 3 when the incoming signal from a transmitter is received, the flow diagram is followed so as to store the new incoming program in the code location pointed to by the code location pointer  23  . It is to be noted that up to five addresses can be stored in the system of the invention. 
     It is seen that the present invention allows a receiving system to respond to one of a plurality of transmitters which have different unique codes which can be stored in the receiver during a program mode. Each time the “program mode switch”  22  is moved to the program position, a different storage area as determined by the switch  23  can be connected so that the new transmitter code would be stored in that address. After all of the address storage capacity have been used additional codes would erase all old codes in the memory address storage before storing a new one. 
     Although the invention has been described with respect to preferred embodiments, it is not to be so limited as changes and modifications may be made which are within the full intended scope as defined by the appended claims.

Summary:
The present invention comprises a system for remote control of garage doors and other devices wherein an extremely large number of codes are available for remote transmitters for operating the garage operator and wherein each transmitter has its own unique and permanent nonuser changeable code. The receiver at the garage door operator is capable of storing and remembering a number of different codes corresponding to different transmitters such that the receiver can be programmed so as to actuated by more than one transmitted code thus allowing two or more transmitters to actuate the same garage door operator and wherein the receiver stores the valid codes for the different transmitters.