Document transmission method upon generation of an error during communication in a facsimile system

A method for transmitting a document when an error is generated during communication in a facsimile system, contemplates the steps of: determining whether the error is generated in a call setup phase during the communication performed in accordance with a predetermined protocol; automatically re-dialing a receiving subscriber's telephone number to transmit image data from the document, when the error is generated in the call setup phase; determining whether the error is generated during transmission of the image data from the document, when the error is not generated in the call setup phase; and automatically re-dialing the receiving subscriber's telephone number and beginning transmission at a next page of the document immediately following a page of the document that generated the error, when the error is generated during the transmission of the image data.

CROSS-REFERENCE TO RELATED APPLICATIONS 
This application makes reference to, incorporates the same herein, and 
claims all benefits accruing under 35 U.S.C. .sctn.119 arising from an 
application for Document Transmission Method Upon Generation of n Error 
During Communication In A Facsimile System earlier filed in the Korean 
Industrial Property Office on Jun. 30, 1995 and there duly assigned Serial 
No. 18964/1995. 
BACKGROUND OF THE INVENTION 
The present invention relates to a facsimile system, and more particularly, 
to a method for transmitting pages of a document upon generation of an 
error during communication in a facsimile system. 
In a conventional facsimile system, when a user dials a receiving 
subscriber's telephone number after inserting pages of a document to be 
transmitted into a document feeding cassette, the document pages are 
transmitted according to a predetermined protocol. When calling the 
receiving subscriber's facsimile system, the transmitting subscriber's 
facsimile system transmits a calling tone (hereinafter, "CNG") signal to 
the receiving subscriber's facsimile system. In response to the CNG 
signal, the receiving subscriber's facsimile system transmits a called 
station identification (hereinafter, "CED") signal, and subsequently 
transmits a non-standard facilities (hereinafter, "NSF") signal, a called 
subscriber identification (hereinafter, "CSI") signal and a digital 
identification (hereinafter, "DIS") signal. At this time, the transmitting 
subscriber's facsimile system analyzes the NSF signal to thereby determine 
whether or not an image quality change is requested. If an image quality 
change is requested, the transmitting subscriber's facsimile system 
changes the image quality mode according to the image quality change 
request, and transmits a non-standard set up (hereinafter, "NSS") signal, 
a transmitting subscriber identification (hereinafter, "TSI") signal and a 
digital command signal (hereinafter, "DCS") to the receiving subscriber's 
facsimile system. Next, the receiving subscriber's facsimile system 
transmits a confirmation to receive (hereinafter, "CFR") signal to the 
transmitting subscriber's facsimile system. The transmitting subscriber's 
facsimile system transmits image data from a document to the receiving 
subscriber's facsimile system in response to the CFR signal. After one 
page of image data is transmitted, the transmitting subscriber's facsimile 
system transmits an end of page (hereinafter, "EOP") signal to the 
receiving subscriber's facsimile system. In response to the EOP signal, 
the receiving subscriber's facsimile system transmits a message 
confirmation (hereinafter, "MCF") signal to the transmitting subscriber's 
facsimile system, thus completing the transmission and reception of one 
page of image data. Then, in order to receive a next page of image data, 
the receiving subscriber's facsimile system again transmits the NSF, CSI 
and DIS signals to the transmitting subscriber's facsimile system to 
thereby repeat the previously described operations. The protocol for 
transmitting and receiving document images in this manner is prescribed in 
the Consultive Committee in International Telephone and Telegraph 
(hereinafter, "CCITT") recommendation. This protocol, and a protocol in 
accordance with a CCITT.41420 standard is performed through five phases as 
shown in Table &lt;1&gt;. 
TABLE 1 
______________________________________ 
TRANSMITTING SYSTEM RECEIVING SYSTEM 
______________________________________ 
PHASE A 
CALLING(CNG) CALLED STATION 
IDENTIFICATION(CED) 
PHASE B 
COMMAND CAPABILITIES 
INFORMATION IDENTIFICATION 
(NSS + TSI + DCS) 
(NSF + CSI + DIS) 
TRAINING (HIGH SPEED) 
CONFORMATION TO 
(9600/7200/4800/2400) 
RECEIVE (CFR) 
PHASE C 
MESSAGE 
HIGH SPEED 
(9600/7200/4800/2400) 
PHASE D 
END OF MESSAGE CONFIRMATION TO 
(EOP/MPS/EOM/RPI.sub.-- Q) 
RECEIVE 
(MCF/RTP/RTN/PIP/PIN) 
PHASE E 
DISCONNECT THE LINE 
(DCN) 
______________________________________ 
As shown in Table &lt;1&gt;, in phase A, which is a call set-up phase, the 
transmitting and receiving systems exchange the CNG and CED signals. In 
phase B, which is a pre-message procedure phase, the transmitting and 
receiving systems exchange the NSS+TSI+DCS and NSF+CSI+DIS and CFR 
signals. Phase C is a phase for transmitting a facsimile message (image 
data). Phase D is a post-message procedure phase. In phase D, the 
transmitting and receiving systems exchange the EOP/MPS/EOM/RPI.sub.-- Q 
and the MCF/RTP/RTN/PIP/PIN signals. In phase E, the transmitting system 
transmits a disconnection (hereinafter, "DCN") signal to the receiving 
system, and the call is released. 
In the conventional facsimile system, however, if an error is generated or 
there is no response from a counterpart's facsimile system during 
transmission and reception of document data according to the previously 
described protocol, a message indicating that an error has occurred or 
that no response has occurred is displayed. If the error is generated 
during transmission of the document data, the error message is displayed 
and transmission is then terminated. At this time, if a user presses a 
re-dial key, the receiving subscriber's telephone number is re-dialed at a 
predetermined time interval, and communication is re-attempted as many 
times as is designated by the user. 
In this conventional facsimile system, when an error is generated during 
communication, only the error message is displayed and transmission of the 
document data is terminated. Therefore, there is a disadvantage in that 
when an error is generated while transmitting several document pages, the 
user has to re-transmit all of the document pages, irrespective of whether 
some of the pages have been successfully transmitted, thereby wasting the 
user's time and incurring unnecessary telephone charges. The present 
invention is directed towards solving this problem. 
SUMMARY OF THE INVENTION 
Therefore, it is an object of the present invention to provide a method for 
transmitting remaining pages of a document when an error is generated 
during communication in a facsimile system. 
It is another object to provide a method for transmitting remaining pages 
of a document by automatically re-dialing the receiving subscriber's 
telephone number when an error is generated during communication in a 
facsimile system. 
It is still another object to provide a facsimile transmission method that 
eliminates the inconvenience of having to re-transmit pages of a document 
that have already been properly transmitted to a receiving subscriber. 
It is yet another object to provide a facsimile transmission method that 
reduces telephone charges. 
To achieve these and other objects, the present invention provides a method 
for transmitting a document when an error is generated during 
communication in a facsimile system. The method contemplates the steps of: 
determining whether the error is generated in a call setup phase during 
the communication performed in accordance with a predetermined protocol; 
automatically re-dialing a receiving subscriber's telephone number to 
transmit image data from the document, when the error is generated in the 
call setup phase; determining whether the error is generated during 
transmission of the image data from the document, when the error is not 
generated in the call setup phase; and automatically re-dialing the 
receiving subscriber's telephone number and beginning transmission at a 
next page of the document immediately following a page of the document 
that generated the error, when the error is generated during the 
transmission of the image data.

DETAILED DESCRIPTION OF THE INVENTION 
Turning now to the drawings and referring to FIG. 1, a block diagram 
illustrating the facsimile system constructed according to the principles 
of the present invention is shown. In FIG. 1, a central processing unit 
(hereinafter, "CPU") 10 controls the facsimile system according to a given 
program in order to re-transmit a document when an error is generated 
during communication. A memory 20 stores the program, including protocol 
data and character data, and accesses data under the control of CPU 10. An 
operating panel (hereinafter, "OPE") 30 includes a plurality of keys, such 
as a dial key, a density designation key, a resolution designation key and 
a function designation key, etc., for generating various key data, and 
further includes a display unit for displaying the data. A scanner 40 
scans image data from a document for conversion into digital image data, 
and transmits the digital image data to CPU 10. A modulator-demodulator 
(hereinafter, "MODEM") 50 modulates data provided from CPU 10 to thereby 
output analog data, and simultaneously demodulates received analog data to 
thereby output digital data under the control of CPU 10. A network control 
unit (hereinafter, "NCU") 60 connects a speech loop of a telephone line, 
and interfaces signals between MODEM 20 and the telephone line under the 
control of CPU 10. A printer 70 prints received data according to a 
control signal provided from CPU 10. 
FIG. 2 is a flow chart illustrating a method for transmitting a document 
upon generation of an error during communication in a facsimile system 
according to the principles of the present invention. Briefly, the method 
of FIG. 2 contemplates the steps of: determining whether or not an error 
is generated in phase A or B during communication in accordance with a 
predetermined protocol; automatically re-dialing a receiving subscriber's 
telephone number to thereby transmit document pages when an error is 
generated in phase A or B; determining whether or not an error is 
generated in phase C, D or E when an error is not generated in phase A or 
B; and automatically re-dialing the receiving subscriber's telephone 
number to thereby begin transmission at a next page following an error 
page when an error is generated in phase C, D or E. 
With reference to FIGS. 1 and 2, the preferred embodiment of the present 
invention will now be described in detail. 
The facsimile system of the present invention may be generally provided 
with two distinct document transmission methods. With the first method, 
after the document is inserted and the receiving subscriber's telephone 
number is dialed, the facsimile system scans all of the pages of the 
document to thereby store all of the scanned image data from the document 
in memory, and then performs the protocol, thereby transmitting the 
document data. With the second method, however, the facsimile system scans 
image data from the document according to the protocol, thereby 
transmitting the document data. When employing the first method, the 
facsimile system transmits document data after scanning image data from 
the document and storing all of the scanned image data in memory. 
Therefore, with the first method, the document page that generates an 
error, as well as the remaining document pages, can be transmitted. On the 
other hand, when employing the second method, the facsimile system 
transmits image data from the document according to the protocol. 
Therefore, with the second method, when an error is generated during 
communication, only the document pages remaining after the document page 
that generates the error can be transmitted. 
With reference to FIG. 2, the operations of transmitting image data when an 
error is generated during communication in a facsimile system according to 
the present invention will be explained. In step 101, CPU 10 determines 
whether or not the document is inserted into the document feeding 
cassette, and if the document is inserted, proceeds to step 102. In step 
102, CPU 10 determines whether or not the system is in an off-hook state, 
and if the system is in an off-hook state, proceeds to step 103. In step 
103, CPU 10 receives the telephone number of a receiving subscriber 
through OPE 30, and dials the received telephone number. Then, in step 
104, CPU 10 begins performance of the protocol previously described in 
Table 1 to thereby transmit image data from the document to the receiving 
subscriber's facsimile system. During performance of the protocol, CPU 10 
determines whether an error is generated in phase A, in step 105. If no 
error is generated in phase A, CPU 10 proceeds to step 106 to determine 
whether an error is generated in phase B. If an error is generated in 
either phase A or phase B, CPU 10 proceeds to step 107 and performs an 
automatic re-dialing operation, thereby transmitting the document from the 
beginning. That is, all of the pages of the document are transmitted. 
Next, during continued performance of the document transmission protocol, 
CPU 10 determines whether an error is generated in phase C, D or E, in 
steps 108 through 110, respectively. If an error is generated in phase C, 
D or E, CPU 10 proceeds to step 111 to thereby determine whether or not 
image data from the document page that generates the error is stored in 
memory 20. If the image data from the document page generating the error 
is stored in memory 20, CPU 10 proceeds to step 112 and prepares for 
transmission of the document beginning at, and including, the page that 
generated the error, and then proceeds to step 107. In step 107, CPU 10 
automatically re-dials the receiving subscriber's telephone number. CPU 10 
then proceeds back to step 104 to transmit the remaining document pages, 
including the page that generated the error (i.e., error page). On the 
other hand, if in step 111, image data from the document page generating 
the error has not been stored, CPU 10 proceeds to step 113 and prepares 
for transmission of the document beginning at the next document page 
immediately following the document page that generated the error, and then 
returns to step 107. In step 107, CPU 10 automatically re-dials the 
receiving subscriber's telephone number. CPU 10 then proceeds back to step 
104 to transmit the document pages remaining after the page that generated 
the error. That is, in the situation where image data of the scanned 
document is transmitted according to the protocol without being stored in 
memory 20, if an error is generated in steps 108 through 110, CPU 10 
prepares for transmission of the document beginning at the next document 
page following the document page that generated the error, and then 
proceeds to step 107. 
In step 114, CPU 10 determines whether or not transmission of the document 
is completed, and if not completed, repeatedly performs steps 106 through 
110. Alternatively, if transmission of the document is completed, CPU 10 
proceeds to step 115 to thereby determine whether or not a transmission 
result report output mode is designated, and if the mode is designated, 
proceeds to step 116. In step 116, CPU 10 controls printer 70 to print an 
error message or a message indicating that a document page (Le., error 
page) has been skipped in the transmission process, and then terminates 
the program. 
As previously discussed, if an error is generated while transmitting 
document pages according to the previously described protocol, the 
facsimile system of the present invention automatically re-dials the 
receiving subscriber's telephone number to thereby continue transmission 
of the document until the communication is finished. Accordingly, when an 
error is generated during communication, the user does not need to 
re-transmit the document pages which have already been transmitted. As a 
result, the present invention provides advantages in that it is capable of 
preventing unnecessary telephones charges, and also saves the time that is 
wasted when document pages are re-transmitted. 
While there have been illustrated and described what are considered to be 
preferred embodiments of the present invention, it will be understood by 
those skilled in the art that various changes and modifications may be 
made, and equivalents may be substituted for elements thereof without 
departing from the true scope of the present invention. In addition, many 
modifications may be made to adapt a particular situation to the teaching 
of the present invention without departing from the central scope thereof. 
Therefore, it is intended that the present invention not be limited to the 
particular embodiments disclosed as the best mode contemplated for 
carrying out the present invention, but that the present invention 
includes all embodiments falling within the scope of the appended claims.