Communication apparatus

Abstract: An image communication apparatus comprises a communication unit for communicating data with a destination station through a line, a detector for detecting pulses of a busy tone sent from the line, a control unit for causing the communication unit to disconnect the line when the detector detects the pulses of the busy tone, and a setting unit for setting the number of pulses of the busy tone to be detected by the detector. The preset number of pulses is variable by operator setting. The control unit causes the communication unit to disconnect the line when the number of pulses of the busy tone detected by the detector reaches the count preset by the setting unit.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a communication apparatus which disconnects a line by detecting an incoming signal from a destination station or a switchboard or exchanger. Related Background Art In a prior art communication apparatus such as a facsimile apparatus, when a signal sent from a switchboard such as a busy tone (BT) signal is to be detected, it is tested for a predetermined level width as a valid signal, a frequency at a given time as a valid frequency band and ON/OFF time of the signal as a valid duration. In the prior art, the facsimile apparatus is designed to disconnect the line by detecting a signal (busy tone) sent from the switchboard at the time of call, or by detecting a signal (busy tone) sent from the switchboard when a destination station disconnects the line after the call. Where the destination station is an apparatus which sends out only a facsimile signal, no problem arises. However, a recent facsimile apparatus has an automatic recording and responding function which sends out a response message other than the facsimile signal. Components (frequency, level, etc.) of the response message include components of the signal (busy tone) from the switchboard and the periods thereof are very close to each other. As a result, the response message and the signal (busy tone) from the switchboard are frequently misdetected and even if the destination station was accessed the line may be disconnected by the detection of the response message from the destination station. SUMMARY OF THE INVENTION it is an object of the present invention, which is defined in claim 1, to improve a commmunication apparatus in the light of the above problems. It is another object of the present invention to provide a communication apparatus which allows an operator to set the number of times of detection of a pulse when a frequency, a signal level or a period of the incoming signal from a communication line is tested to detect a predetermined signal. Other objects of the present invention will be apparent from the following description and drawings of the preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 shows a block diagram of an embodiment of a facsimile apparatus, Fig. 2 shows a detail of the number of times of period setting circuit, Fig. 3 shows a switching circuit for setting a predetermined number of times of period, Fig. 4 shows a procedure for setting the number of times of period as a count, Fig. 5 shows a flow chart of an operation of the embodiment, Fig. 6 shows a flow chart of an operation of the embodiment, Fig. 7 shows a flow chart of an operation of the embodiment, and Fig. 8 shows a flow chart of an operation of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is now explained with reference to the drawings. Fig. 1 shows an embodiment of the present invention. Numerals 1 and 2 denote a frequency detector and a level detector which detect a frequency and a level of a signal inputted from a switchboard or a destination station through a line. Numeral 3 denotes a control unit comprising a CPU for effecting the disconnection of the line based on the outputs from the frequency detector 1 and the level detector 2 and the time measurement, numeral 4 denotes a communication unit for communicating with the destination station, numeral 5 denotes a memory unit for storing the number of times of period such as a disconnection signal (busy tone) from the switchboard, numeral 6 denotes a time measurement unit for measuring an ON/OFF time of a signal inputted from the switchboard or the destination station through the line, and numeral 7 denotes a number of times of period setting unit comprising a display unit and a console unit. Fig. 2 shows a detail of the number of times of period setting unit 7. Numeral 8 denotes a display unit for indicating an operation when the number of times of period is to be set, numeral 9 denotes a console unit for setting the number of times of period, numeral 10 denotes a number of times of period setting key for indicating the start of setting of the number of times of period, numeral 11 denotes a setting key for setting the number of times of period in the memory unit 5, and numeral 12 denotes ten-key buttons for setting the number of times of period. An operation of setting the number of times of period is now explained with reference to an operation chart and a flow chart. Referring to Figs. 4 and 5, the number of times of period setting key 10 is depressed in a step S1 and a number of times of period setting screen is displayed on the display unit 8 in step S2. Then, in step S3, the currently set number of times of period is displayed as an input screen for a modified value. In steps S4 and S5, the modified value is set by the ten-keys 12, and in step S6, the setting key 1 is depressed to set the current value in the memory unit 5 as the modified value and the setting of the number of times of period is completed. As shown in Fig. 3, a modified value of the number of times of period may be predetermined and the predetermined number of times may be selected by a switch. In this case, four steps of periods (for example, 2, 4, 6 and 8 periods) may be set by using the bits 0 and 1 by a bit switch (which may be either hardware or software) and the bits may be changed to change the number of times of period. An operation to determine the disconnection of the line by the setting of the number of times of period is now explained with reference to Figs. 6, 7 and 8. Fig. 6 shows a flow chart of an operation to prevent the misdetection of a busy tone by a response of an automatic recording and responding telephone sent from the destination station when it is called. In step S11, a dial tone is sent to the destination station to be called. In a step S12, a time T1 is set in the timer and the timer operation is started. In step S13, a CNG signal is sent. In step S14, a DIS signal from the destination station is detected. In step S15, a busy tone is detected. In step S16, a time-over of time T1 is measured. The routine of steps S13 - S16 is repeated until the time-over of the time T1. If the busy tone is detected in step S15 or the time-over is detected in step S16, the process proceeds to step S20 to disconnect the line. If the DIS signal is detected in step S14, a communication protocol is conducted in step S17, an image is sent in step S18, a post protocol is effected in step S19, and the line is disconnected in step S20. A detail of the detection of the busy tone in the step S15 is now explained. In step S15, the number of times of signal pulses of the busy tone signal set in the number of times of period setting operation described above is counted. The frequency and level of the signal sent from the line shown in Fig. 1 are detected by the frequency detector 1 and the level detector 2. The frequency corresponding to the busy tone is detected by the frequency detector 1 and if the level detector 2 detects that the signal level has exceeded a predetermined level, the busy signal is turned on and the ON/OFF time thereof is measured by the control unit 3. It is compared with the ON/OFF time of the busy signal to detect the pulse of the busy signal. The number of times of the pulses of the busy signal is compared with setting and if the pulses of the predetermined count are detected, the detection of the busy signal is detected. If the pulses of the busy signal are detected in step S15 of Fig. 6 by the preset number of times, the line is disconnected in the step S20. A receiving operation is now explained with reference to Fig. 7. In step S21, a call is waited and if the call is detected a time T1 is set in the timer in step S22 and it is started. In step S23, a signal DIS is sent and a destination station signal (DCS) is received in step S24. When the DCS is received, an image is received in steps S28 et seq. and if the DCS is not received, the process proceeds to step S25. In step S25, the busy tone is detected a preset number of times as it is in step S15 of Fig. 6, when the busy tone is detected, the line is disconnected in step S27, and if the busy tone is not detected, the time-over of the time T1 is monitored in step S26. In step S28, a pre-protocol is effected. In step S29, an image is received. In step S30, a post protocol is effected. Referring to Fig. 8, an operation of detecting a busy tone in an F/T switch mode is explained. In step S31, a call is monitored. In step S32, a time T2 for detecting a CNG signal is set. In step S33, the CNG signal is detected. If the CNG signal is detected, an image is received in steps S45 et seq. If the CNG signal is not detected, the busy tone is detected in step S34. If the busy tone is detected, the line is disconnected in step S44. In step S35, steps S33 - S34 are repeated while the time-over of the time T2 is monitored. If the time-over is detected, the process proceeds to step S36. In step S36, a bell ringing timer T3 for calling an operator is set. In step S37, a bell of the telephone set is rung to call the operator and it is continued to be rung until the time-over of the time T3 is detected in step S38. If the operator hooks of the telephone set during this period, the bell ring is stopped and the F/T switch mode is terminated. When the time T3 is over, the process proceeds to step S39. In step S39, the timer T1 is set. Steps S39 et seq. are same as those of the receiving operation described above. In accordance with the present invention, the operator can change the number of times of period of the input signal to discriminate the signal from the switchboard from the speech signal (for example, response message) from the line.

Claims: An image communication apparatus comprising: communication means (4) for communicating data with a destination station through a line; detection means (1, 2) for detecting pulses of a busy tone sent from the line; and control means (3) for causing said communication means to disconnect the line when said detection means detects the pulses of the busy tone; characterized by further comprising setting means (7) for setting the number of pulses of the busy tone to be detected by said detection means; said preset number of pulses being variable by operator setting; and said control means causing said communication means to disconnect the line when the number of pulses of the busy tone detected by said detection means reaches the count preset by said setting means. An image communication apparatus according to claim 1 wherein said image communication apparatus is a facsimile apparatus. An image communication apparatus according to claim 1 wherein said detection means detects a frequency and a level of a signal sent from the line, sets a detection signal ON if the signal has a frequency of the busy tone and a level higher than a predetermined level, detects an ON/OFF state of the detection signal, measures an ON/OFF time of the detection signal to determine a period, and if the period of the signal sent from the line corresponds to the signal of the busy tone, determines that the signal sent from the line is the busy tone signal. An image communication apparatus according to claim 1 wherein said setting means has settings of the number of pulses and the operator selects one of them. An image communication apparatus according to claim 4 wherein said setting means is a bit switch and one of the settings is selected by a position of said bit switch. An image communication apparatus according to claim 1 wherein the setting to said setting means is effected by the operator through ten-keys.

Inventors: MATSUMOTO KOICHI, MATSUMOTO, KOICHI
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1993
Main classification: H04N1
IPC codes: H04M11, H04N1