Data communication apparatus
This application is a continuation of application Ser. No. 471,004 filed Jan. 25, 1990 (abandoned) which is a continuation of application Ser. No. 165,477 filed Mar. 8, 1988 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     5. FIELD OF THE INVENTION 
     The present invention relates to a data communication apparatus having a speech communication function and a data communication function. 
     2. Related Background Art 
     A facsimile system is known as an apparatus of this type. In the facsimile system, a telephone line is switched to the facsimile or telephone set side to perform image data communication or speech communication. When a start key in the facsimile system is depressed to perform image communication, the transmission line is switched from the telephone set to the facsimile system, and communication is started. In other words, in a conventional facsimile system, the start key must be depressed to start facsimile communication. 
     In recent years, there has become available is a communication system including one facsimile system and a plurality of telephone sets, all of which are commonly connected to a communication line. Examples of such a communication system are described in U.S. Ser. No. 108,915 (filed on Oct. 15, 1987) and U.S. Ser. No. 106,783 (filed on Oct. 13, 1987) by the present applicant. In the above-mentioned system, a plurality of operators share one facsimile system, and therefore, the facsimile system is located at a place remote from the telephone sets (i.e., operators). For this reason, U.S. Ser. No. 108,915 describes an arrangement in which a facsimile system can be operated from each telephone set, and U.S. Ser. No. 106,783 describes an arrangement in which an operating state of a facsimile system is displayed on each telephone set. In a communication system in which, particularly, one facsimile system and a plurality of telephone sets share a communication line, since the facsimile system must be operated at a remote area, it is inconvenient for each operator to operate the start key of the remote facsimile system every time image communication is required. Prior art systems in which a plurality of telephone sets and a facsimile system are selectively switched with respect to a plurality of communication lines are described in U.S. Ser. No. 813,514 (filed on Dec. 26, 1985) and U.S. Pat. No. 823,286 filed on Jan. 28, 1986). Arrangements in which the number of keys in the facsimile system is decreased are described in U.S. Pat. No. 4,502,080  and U.S. Pat. No 4,567,322. U.S. Pat. No. 4,502,080 describes an arrangement in which transmission, reception, and copying can be selectively performed by a single key. U.S. Pat. No. 4,567,322 describes an arrangement in which transmission, reception, copying, and recording paper cutting can be performed by a single key. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to eliminate the conventional problems described above. 
     It is another object of the present invention to improve a data communication apparatus. 
     It is still another object of the present invention to allow data communication without depression of a start key of the data communication apparatus. It is still another object of the present invention to perform data communication if transmission data is set in line connection with a partner. 
     It is still another object of the present invention to perform data communication if transmission data is set in detection of a response from a partner. 
     It is still another object of the present invention to provide a communication system including a data communication apparatus and a plurality of speech communication apparatuses, all of which are connected to a common transmission line, wherein data communication can be performed without depressing a start key in the data communication apparatus. 
     The above and other objects, features, and advantages of the present invention will be apparent from the detailed description of preferred embodiments in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a data communication apparatus according to a first embodiment of the present invention; 
     FIG. 2 is a flow chart for explaining control operation of a controller in the first embodiment; 
     FIG. 3 is a perspective view showing a telephone set terminal in the first embodiment; 
     FIG. 4 is a block diagram of a data communication apparatus according to a second embodiment of the present invention; and 
     FIG. 5 is a flow chart for explaining control operation of a controller in the second embodiemnt. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described with reference to the accompanying drawings. 
     FIG. 1 is a block diagram of a data communication apparatus according to a first embodiment of the present invention. 
     A non-telephone terminal comprises a line control section 20 and a facsimile section 30. A plurality of telephone set terminals 41, 42, and 43 can be connected to the control section 20. The number of telephone set terminals may be arbitrarily determined. 
     The line control section 20 includes an incoming detector circuit 21, a ring back tone detector circuit 22, a switching circuit 23, and a microcomputer 24. The ring back tone detector circuit 22 serves as a ring back tone detecting means for detecting a ring back tone from the reception side. 
     The facsimile section 30 includes an NCU/modem 31, a console unit 32, a display unit 33, a recorder unit 34, a memory unit 35, a reader unit 36, and a CPU 37. 
     The reader unit 36 reads a transmission original and detects that the transmission original is set in a non-telephone terminal. The reader unit 36 serves as a transmission original detecting means. The microcomputer 24 serves as a switching control means for detecting a ring back tone and switching a telephone line 50 from the telephone set terminals 41 to 43 to the facsimile section 30 when the transmission original is set. 
     FIG. 3 shows an arrangement of the telephone set terminal 41 in the first embodiment. 
     The telephone set terminals 42 and 43 are arranged in the same manner as in the telephone set terminal 41. 
     The operation of the first embodiment will be described below. 
     FIG. 2 is a flow chart for explaining the operation of the first embodiment. 
     A calling station uses one of the telephone set terminals 41 to 43. An operator depresses an outside line key arranged in the selected telephone set terminal to engage the telephone set terminal with the outside line (S1 and S2). Assume that the telephone set terminal 41 is used for calling. When the outside line is engaged with the telephone set terminal 41, a message &#34;OUTSIDE LINE OK&#34; is displayed on a display unit in the telephone set terminal 41. After the operator reads this message, he picks up a handset, hears a dial tone representing a state wherein a dial signal can be accepted by the switching circuit 23, and then dials a telephone number (S3, S4, and S5). 
     If a line is not busy, the operator does not hear a busy tone (S6) but can hear a ring back tone as a tone for calling the partner. The ring bcak tone detector circuit 22 detects the ring back tone (S7). The reader unit 36 detects whether the transmission original is set in the reader unit 36 (S8). If YES in step S8, the telephone line 50 is swithced to the facsimile section 30 (S9). When a reverse signal (polarity reverse signal) is received (S10), facsimile communication is started (S11). 
     However, if the transmission original is not set (S8), normal speech communication is performed (S12). 
     When facsimile communication is started (S11), a message &#34;FAX COMMUNICATION&#34; is displayed on the telephone set terminal 41. The operator reads this message and hangs up the phone. 
     When the microcomputer 24 receives a ring back tone detection signal from the detector circuit 22, the microcomputer 24 requests to the CPU 37 in the facsimile section 30 a signal representing the presence/absence of the transmission original. When the CPU 37 receives this request signal, it receives an original presence/absence signal from the reader unit 36. The original presence/absence signal is sent to the microcomputer 24. When the microcomputer 24 receives the transmission presence signal, the microcomputer 24 causes the switching circuit 23 to switch the telephone line 50 from the telephone line terminal 41 to the facsimile section 30. 
     In the above embodiment, the facsimile start key is omitted from the telephone set terminal. The ring back tone detector circuit 22 is arranged in place of the facsimile start key. 
     As described above, when facsimile transmission is performed, the operator dials the telephone number of the partner at the selected telephone set terminal and need not operate other keys, thereby simplifying the transmission operations. For example, if the facsimile section 30 is separated from the telephone set terminals 41 to 43 and the original is set in the reader unit 36 in the facsimile section 30, the operator located at the telephone set terminal need not walk to the facsimile section 30 for facsimile transmission. Therefore, facsimile transmission can be performed even if the operator is located near the telephone set terminal. 
     A second embodiment of the present invention will be described below. 
     FIG. 4 is a block diagram showing an arrangement of the second embodiment. The same reference numerals as in FIG. 1 denote the same parts in FIG. 4. 
     A line control section 20 includes an incoming detector circuit 21&#39; for detecting an incoming call from a telephone line 50, and a frequency detector circuit 22&#39; for detecting a facsimile identification signal from the partner. The frequency detector circuit 22&#39; serves as a facsimile identification signal detecting means. 
     A reverse detector circuit 25&#39; detects the reverse of the polarity of the line 50. 
     A telephone set terminal 41 in the second embodiment is the same as that in FIG. 3. 
     The operation of the second embodiment will be described below. 
     FIG. 5 is a flow chart showing an operation of the second embodiment. 
     An operator at a calling station uses one of the telephone set terminals 41 to 43 and depresses an outside line key arranged in the selected telephone set terminal to engage it with the outside line (S21 and S22). Assume that the telephone set terminal 41 is used for calling. When the outside line is engaged with the telephone set terminal 41, a message &#34;OUTSIDE LINE OK&#34; is displayed on a display unit in the telephone set terminal 41. After the operator reads this message, he picks up a handset, hears a dial tone representing a state wherein a dial signal can be accepted by the switching circuit 23, and then dials a telephone number (S23, S24, and S25). 
     If a line is not busy, the operator does not hear a busy tone (S26) but can hear a ring back tone as a tone for calling the partner. The ring back tone detector circuit 22&#39; detects the ring back tone (S27). 
     When the ring back tone is detected and the reverse of the polarity can be detected (S28), the reader unit 36 detects that the transmission original has been set in the reader unit 36 (S29). However, if the transmission original is not set, normal speech communication is performed (S30). 
     When the transmission original is set, a timer having a predetermined timer time is started (S31). If the frequency detector circuit 22&#39; detects a facsimile identification signal within the timer time (S32), the telephone line 50 is switched to the facsimile section 30 (S33), and facsimile communication is performed (S34). When facsimile communication is started, a message &#34;FAX COMMUNICATION&#34; is displayed on the telephone set terminal 41. The operator reads this message and hangs up the phone. 
     However, if the facsimile identification signal cannot be detected within the timer time (S35), the telephone set terminal 41 is disengaged from the telephone line 50 (S36). 
     When the microcomputer 24 receives a ring back tone detection signal from the detector circuit 22&#39; and reverse detection signal from the reverse detector circuit 25&#39;, the microcomputer 24 requests to the CPU 37 in the facsimile section 30 a signal representing the presence/absence of the transmission original. When the CPU 37 receives this request signal, it fetches an original presence/absence signal from the reader 36 and sends it to the microcomputer 24. When the microcomputer 24 receives a transmission original presence signal, the microcomputer 24 causes the timer to start. When the microcomputer 24 receives a facsimile identification signal from the frequency detector circuit 22&#39;, the microcomputer 24 causes the switching circuit 23 to switch the telephone line 50 from the telephone set terminal 41 to the facsimile section 30. 
     In the second embodiment, the facsimile start key is omitted from the telephone set terminal. The frequency detector circuit 22&#39; is arranged in place of the facsimile start key. 
     As described above, when facsimile transmission is performed, the operator dials the telephone number of the partner at the selected telephone set terminal and need not operate other keys, thereby simplifying the transmission operations. For example, if the facsimile section 30 is separated from the telephone set terminals 41 to 43 and the original is set in the reader unit 36 in the facsimile section 30, the operator located at the telephone set terminal need not walk to the facsimile section 30 for facsimile transmission. Therefore, facsimile transmission can be performed even if the operator is located near the telephone set terminal. 
     According to the embodiments described above, in a communication system wherein a plurality of telephone set terminals can be connected to a non-telephone terminal incorporating a facsimile section and a line control section, operations for facsimile transmission can be simplified. 
     In the above embodiment, the microcomputer checks if the original is set in the reader unit 36 of the facsimile section after the operator dials the partner. However, image data to be transmitted may be stored in the memory unit 35 beforehand, the partner&#39;s telephone number may be dialed, and it may be then checked whether the image data to be transmitted is stored in the memory unit 35. 
     In the above embodiment, the plurality of telephone set terminals and the facsimile system share the common transmission line. However, the plurality of telephone set terminals need not be used, but only one telephone set terminal may be used. In addition, the data communication apparatus is not limited to the facsimile system, but may be replaced with an apparatus (e.g., a teletex or a wordprocessor) for transmitting code data. In this case, it must be checked if the transmission data is stored in the memory unit 35. 
     The present invention is not limited to the particular embodiments described above. Various changes and modifications may be made within the spirit and scope of the invention.