communication equipment

Abstract

The present invention provides a communication device. The communication device comprises: a first connection portion connected to a telephone line network; a first path; a first detection unit that detects a voltage on the first path; a second connection portion located downstream of the first connection portion and connected to an external telephone; a second path having a resistor; a second detection unit that detects a current flowing in the second path; a switching unit that switches the line to a non-connected state, not connected to the second detection unit, when the line to the modem is disconnected, and switches the line to a connected state, connected to the second detection unit, when the line to the modem is closed; and a determination unit that determines whether the external telephone is off-hook based on a detection result of the first detection unit in the non-connected state, and determines whether the external telephone is off-hook based on a detection result of the second detection unit in the connected state.

Description

Technical Field

[0001] The present disclosure relates to communication devices. Background Art

[0002] The following communication device is known, which includes a first communication unit and a connection unit, wherein the first communication unit is connected to a telephone line for communication, and the connection unit is connected to the telephone line via the first communication unit and is used to connect to a second communication unit for communication, wherein the first communication unit has: a first switch unit, which is used to connect the telephone line to the first communication unit or the second communication unit; a first path unit, which connects the second communication unit to the telephone line via the first switch unit; a second path unit, which directly connects the second communication unit to the telephone line; a second switching unit, which connects the second communication unit to the first path unit or the second path unit; a first hang-up detection unit, which is connected to the first path unit; and a second hang-up detection unit, which is connected between the telephone line of the second path unit and the second switch unit (refer to Japanese Patent Laid-Open No. 2004-64601). Summary of the Invention

[0003] An object of the present disclosure is to simultaneously achieve detection accuracy of an off-hook state of an external telephone and suppression of resistance loss in a path.

[0004] According to a first aspect of the present disclosure, there is provided a communication device comprising:

[0005] a first connection portion connected to a telephone line network;

[0006] a first path, which is a path from the first connection portion toward a modem located downstream of the telephone line network;

[0007] a first detection unit, configured to detect a voltage of the first path;

[0008] a second connecting portion, located downstream of the first connecting portion, the second connecting portion being connected to an external telephone;

[0009] a second path, which is a path between the second connection portion and the first connection portion, and has resistance in the second path;

[0010] a second detection unit configured to detect a current flowing in the second path;

[0011] a switching unit that switches the line to a non-connected state not connected to the second detection unit when the line toward the modem is disconnected, and switches the line to a connected state connected to the second detection unit when the line toward the modem is closed; and

[0012] A determination unit determines whether the external telephone is off-hook according to the detection result of the first detection unit in the non-connected state, and determines whether the external telephone is off-hook by the second detection unit in the connected state.

[0013] According to the second aspect of the present disclosure, the determination unit determines that the external telephone is off-hook when the voltage between the first path units detected by the first detection unit changes beyond a predetermined threshold value.

[0014] According to a third embodiment of the present disclosure, the second detection unit is a photocoupler, and the second detection unit detects the current flowing in the second path unit, wherein the photocoupler is composed of a light-emitting element and a phototransistor, the light-emitting element is connected in parallel with the resistor and emits light in response to the flow of current, and the phototransistor is turned on by the light emission of the light-emitting element.

[0015] According to a fourth aspect of the present disclosure, the communication device has a TEL / FAX automatic switching function for automatically switching between an external telephone and a fax function. The first detection unit closes the line based on an incoming signal from the telephone line network, and fax communication is started when the incoming signal includes a CNG signal indicating a fax sending terminal. When the incoming signal does not include a CNG signal indicating a fax sending terminal, the switching unit switches to the connected state to determine whether the external telephone has been picked up.

[0016] (Effect)

[0017] According to the first aspect, off-hook can be detected with high accuracy even when the line is closed, compared to the case where detection is performed only by the first detection unit, and resistance loss in the path to the external telephone can be suppressed, compared to the case where detection is performed only by the second detection unit.

[0018] According to the second aspect, the off-hook state can be detected while suppressing resistance loss in the path toward the external telephone.

[0019] According to the third aspect, the current detection accuracy can be improved compared to the case where detection is performed at a position other than the resistor.

[0020] According to the fourth aspect, it is possible to improve the accuracy of detecting the off-hook state of the external telephone during automatic TEL / FAX switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a diagram showing the circuit configuration of a communication device.

[0022] Figure 2 This is a diagram showing a circuit configuration of a communication device in which a switch is connected to the disconnect side.

[0023] Figure 3 1 is a diagram showing a circuit configuration of a communication device in which a switch is connected to a conductive side.

[0024] Figure 4 This is a flowchart showing the flow of operations for determining an off-hook of an external telephone in a communication device having a TEL / FAX automatic switching function.

[0025] Figure 5 1 is a diagram showing a circuit configuration of a communication device according to Comparative Example 1 including a power supply circuit.

[0026] Figure 6 1 is a diagram showing a circuit configuration of a communication device according to Comparative Example 2 that does not include a power supply circuit.

[0027] Figure 7 3 is a diagram showing a circuit configuration of a communication device according to Comparative Example 3 having a semiconductorized DAA. DETAILED DESCRIPTION

[0028] Next, the present disclosure will be described in more detail with reference to the accompanying drawings by listing the following embodiments and specific examples. However, the present disclosure is not limited to these embodiments and specific examples.

[0029] In the following description using the drawings, the drawings are schematic and the ratios of dimensions and the like are different from actual ones. For ease of understanding, parts other than those necessary for explanation are omitted as appropriate.

[0030] (1) Overall structure and operation of the communication device

[0031] Figure 1 1 is a diagram showing a circuit configuration of a communication device 1 according to an embodiment of the present application. Figure 1 , the communication device 1 is shown in a state where a telephone line network 50 and an external telephone 60 are connected.

[0032] The communication device 1 includes a pair of line connection terminals 11 as an example of a first connection part, a pair of telephone connection terminals 12 as an example of a second connection part, a semiconductor DAA (Direct Access Arrangement) 14 as an example of a first detection unit, a resistor 15A, a photocoupler 16 as an example of a second detection unit, a switching switch 17 as an example of a switching unit, a transformer 18, a semiconductor switch 19, a modem 30, an ASIC 40, a ROM 43, a RAM 44, an image forming unit 45, an image reading unit 46, and an operation display unit 47.

[0033] The line connection terminal 11 and the telephone connection terminal 12 are terminals provided so as to be able to connect lines or devices outside the communication device 1 , and are, for example, modular jacks.

[0034] The line connection terminals 11 are connected to a switch (not shown) via the telephone line network 50. The telephone connection terminals 12 are terminals that can be connected to an external telephone 60. The pair of line connection terminals 11 includes terminals 11A and 11B. The pair of telephone connection terminals 12 includes terminals 12A and 12B.

[0035] The semiconductor DAA 14 includes a voltage detection unit 21 , a line signal receiving unit 22 , a line signal transmitting unit 23 , a data input / output unit 24 , a well-known loop detection circuit (not shown), and the like.

[0036] Voltage detector 21 is connected to telephone line network 50 via line connection terminal 11. Terminal 11A and voltage detector 21 are connected via first transmission path 13A, an example of a first path, and terminal 11B and voltage detector 21 are connected via first transmission path 13B.

[0037] The voltage detection unit 21 detects the line voltage VS ( Figure 1 Schematically shown in FIG).

[0038] The line signal receiving unit 22 closes the telephone line network 50 during fax reception. The line signal transmitting unit 23 closes the telephone line network 50 during fax transmission. The data input / output unit 24 performs A / D and D / A conversions on fax reception and transmission data. Furthermore, during fax reception, it converts signals such as the ring detection signal sent from the ring detection circuit and the fax reception data output from the line signal receiving unit 22 into serial data. Furthermore, during fax transmission, it separates the control signal for controlling the semiconductor DAA 14, output from the ASIC 40, from the fax transmission data.

[0039] The node N1 on the first transmission path 13A and the terminal 12A of the telephone connection terminal 12 are connected via the second transmission path 13C, which is an example of a second path, via the changeover switch 17 .

[0040] The node N2 on the first transmission path 13B and the terminal 12B of the telephone connection terminal 12 are connected via the changeover switch 17 through the second transmission path 13D, which is an example of a second path.

[0041] In the second transmission path 13D, a resistor 15A and a photocoupler 16 are connected between the terminal 12B of the telephone connection terminal 12 and the switch 17. The photocoupler 16 is composed of a light emitting element that emits light in response to current flow and a phototransistor that is turned on by the light emission of the light emitting element.

[0042] Resistor 15A is a high-resistance current-limiting resistor, specifically a 2000Ω resistor. The detection sensitivity of photocoupler 16 is improved with respect to the current flowing in second transmission path 13D due to resistor 15A. Furthermore, consideration has been given to replacing resistor 15A with a low-resistance resistor 15B, specifically a resistor of approximately 180Ω, to reduce resistance losses. However, this results in low-precision current detection.

[0043] The switching switch 17 is, for example, a wide-cap relay. When the line toward the modem 30 is disconnected, the switching switch 17 switches the line to a non-connected state not connected to the second transmission paths 13C and 13D. When the line toward the modem 30 is closed, the switching switch 17 switches to a connected state connecting the resistor 15A and the photocoupler 16.

[0044] The modem 30 is connected to the semiconductorized DAA 14 via the transformer 18 , and modulates and demodulates fax reception data and fax transmission data.

[0045] The ASIC 40 includes a CPU 41 and has a function of controlling the entire communication device 1 . In the present embodiment, the ASIC 40 functions as a determination unit for determining whether the external telephone 60 is off-hook.

[0046] Furthermore, the CPU 41 is connected to the ROM 43, RAM 44, image forming unit 45, image reading unit 46, and operation display unit 47 via a bus 42. The CPU 41 controls the image forming unit 45, image reading unit 46, operation display unit 47, and the like by executing various programs stored in the ROM 43. The RAM 44 is used as a main storage device for the CPU 41 to execute various processes.

[0047] The image forming unit 45 is, for example, an inkjet or electrophotographic printer, and forms, for example, received fax information as an image on recording paper. The image reading unit 46 reads a document placed on a document table as image data.

[0048] The operation display unit 47 includes, for example, a liquid crystal display, and can display the operating status of the communication device 1. The operation display unit 47 is composed of a combination of a liquid crystal display panel, various operation buttons, a touch panel, and the like. The user of the communication device 1 inputs various settings and instructions via the operation display unit 47. In addition, various information is displayed to the user of the communication device 1 via the liquid crystal display panel.

[0049] (2) Off-hook detection of external telephone

[0050] Figure 2 1 is a diagram showing a circuit configuration of a communication device 1 in which a switch 17 is connected to a disconnection side (S21, S23). Figure 3 1 is a diagram showing a circuit configuration of the communication device 1 in which the switch 17 is connected to the ON side ( S22 , S24 ).

[0051] In communication device 1, a fax machine and an external telephone 60 are connected to a single telephone line network 50, and there is only one line. Therefore, only one of the fax machine and external telephone 60 can be used. Therefore, communication device 1 must constantly monitor the line usage status of external telephone 60 to determine whether it is on-hook or off-hook.

[0052] Figure 5 17B is a diagram showing a circuit configuration of a communication device 100 according to Comparative Example 1 including a power supply circuit 17B.

[0053] The communication device 100 includes a line connection terminal 11 , a telephone connection terminal 12 , a resistor 15B as a low-resistance resistor, a photocoupler 16 , a switch 17A, a power supply circuit 17B for supplying a positive voltage of 24 volts (V), a transformer 18 , and a modem 30 .

[0054] Communication device 100 is in a state where current flows from power supply circuit 17B. When external telephone 60 goes off-hook, the current is detected by resistor 15B connected to second transmission path 13D and photocoupler 16. This current detection information is input to CPU 41 of ASIC 40, which determines that the phone is off-hook.

[0055] The communication device 100 includes the power supply circuit 17B in order to perform off-hook detection by current detection using the resistor 15B and the photocoupler 16 . This increases the internal space of the communication device 100 and may increase the cost.

[0056] Figure 61 is a diagram showing a circuit configuration of a communication device 200 according to Comparative Example 2 that does not include a power supply circuit.

[0057] The communication device 200 includes a line connection terminal 11 , a telephone connection terminal 12 , a resistor 15B, a photocoupler 16 , a switch 17A, a transformer 18 , and a modem 30 .

[0058] In the communication device 200, a constant current flows through the line. When the external telephone 60 goes off-hook, the current is detected by the resistor 15B connected to the second transmission path 13D and the photocoupler 16. This current detection information is input to the CPU 41 of the ASIC 40, which determines whether the phone is off-hook.

[0059] On the other hand, when modem 30 is closed, most of the current flowing from the line flows to transformer 18, and only a small amount of current flows through resistor 15B and photocoupler 16. If the current flowing through second transmission path 13D becomes weak, photocoupler 16 may not operate stably, and off-hook detection may not be performed accurately.

[0060] In this case, even though the external telephone is off-hook, the fact that the call is not detected could prevent the call from starting, or a fax call could be mistakenly detected due to a predetermined timeout. In this configuration, while increasing the current flowing through photocoupler 16 by increasing the resistance of resistor 15B to stabilize the operation of photocoupler 16, the increased resistance of resistor 15B could increase the insertion loss (insurface loss) between the line and external telephone 60.

[0061] Figure 7 1 is a diagram showing a circuit configuration of a communication device 300 according to Comparative Example 3 having a semiconductorized DAA 14 .

[0062] The communication device 300 includes a line connection terminal 11 , a telephone connection terminal 12 , a semiconductor DAA 14 , a changeover switch 17A, a transformer 18 , a semiconductor switch 19 , and a modem 30 .

[0063] In the communication device 300, the semiconductor DAA 14 detects a voltage drop as the line voltage VS between the first transmission path 13A and the first transmission path 13B. This voltage drop detection information is input to the CPU 41 of the ASIC 40, and an off-hook is determined.

[0064] On the other hand, when the modem 30 is closed, Figure 7As schematically shown in FIG, the voltage drop in the line-to-line voltage VS detected by the semiconductor DAA 14 is small, and thus off-hook detection may not be accurately performed. This is particularly likely to occur when the external telephone has a high resistance or when the supplied current is low. In such cases, even if the external telephone is off-hook, the off-hook cannot be detected, preventing the call from being initiated, or the call may be erroneously detected as a fax due to a predetermined timeout.

[0065] The communication device 1 of this embodiment includes a line connection terminal 11 , a telephone connection terminal 12 , a semiconductor DAA 14 , a resistor 15 , a photocoupler 16 , a changeover switch 17 , a transformer 18 , a semiconductor switch 19 , and a modem 30 .

[0066] The node N1 on the first transmission path 13A and the contact S11 of the switch 17 are connected via the second transmission path 13C, and the node N2 on the first transmission path 13B and the contact S12 of the switch 17 are connected via the second transmission path 13D.

[0067] The terminal 12A of the telephone connection terminal 12 and the contact S21 of the changeover switch 17 are connected via the second transmission path 13Ca, and the terminal 12A of the telephone connection terminal 12 and the contact S22 of the changeover switch 17 are connected via the second transmission path 13Cb.

[0068] Terminal 12B of telephone connection terminal 12 and contact S23 of switch 17 are connected via second transmission path 13Da, and terminal 12B of telephone connection terminal 12 and contact S24 of switch 17 are connected to resistor 15A via photocoupler 16 via second transmission path 13Db.

[0069] The resistor 15A is a high-resistance current limiting resistor, and makes the current flowing through the photocoupler 16 have a magnitude that enables the photocoupler 16 to operate stably.

[0070] In the communication device 1 thus configured, generally Figure 2 As shown, the switch 17 is connected to the disconnect side (S21, S23). As a result, the external telephone 60 is connected to the line through the second transmission path 13Ca, the second transmission path 13C, the second transmission path 13Da, and the second transmission path 13D without passing through the resistor 15A and the photocoupler 16.

[0071] When the external telephone 60 is off-hook in this state, the voltage detection unit 21 of the semiconductor DAA 14 detects a voltage drop in the line voltage VS between the first transmission path 13A and the first transmission path 13B. This voltage drop detection information is input to the CPU 41 of the ASIC 40, which determines that the phone is off-hook.

[0072] When receiving the arrival signal, the line signal receiving unit 22 of the semiconductor DAA 14 closes the telephone line network 50. Figure 3 As shown, the switch 17 is turned on (S22, S24). As a result, the external telephone 60 is connected to the line via the second transmission path 13Cb and the second transmission path 13C, the second transmission path 13Db and the second transmission path 13D via the resistor 15A and the photocoupler 16.

[0073] In this state, if the external telephone 60 is off-hook, current is detected by the resistor 15A connected to the second transmission path 13Db and the photocoupler 16. This current detection information is input to the CPU 41 of the ASIC 40, and off-hook is determined.

[0074] As a result, compared to the case where off-hook is detected only by the voltage drop of the semiconductor DAA14, off-hook of the external telephone 60 can be detected with high accuracy even when the line is closed, and compared to the case where detection is performed only by the resistor 15A and the photocoupler 16, insertion loss (insurface loss) in the second transmission path 13D toward the external telephone 60 can be suppressed.

[0075] [Example]

[0076] Figure 4 This is a flowchart showing the operation flow of off-hook determination of an external telephone in a communication device 1 having a TEL / FAX automatic switching function for automatically switching between an external telephone and a fax function.

[0077] The communication device 1 has a "TEL / FAX mode" that determines whether an incoming call is a fax or a phone call, automatically starts receiving a fax, and rings a ringtone to notify the user of an incoming call if the call is a phone call.

[0078] The communication device 1 determines whether an incoming signal has been received (S101). If an incoming signal has been received (S101: Yes), the line signal receiving unit 22 of the semiconductor DAA 14 disconnects the telephone line network 50 (S102) and determines whether the incoming signal is a CNG (calling tone) signal indicating a fax transmission terminal (S103). If the incoming signal is a CNG signal (S103: Yes), fax communication is initiated (S104) and then terminated (S105).

[0079] In the case that the arrival signal is not a CNG signal (S103: No), if Figure 3As shown, the selector switch 17 is switched to the connected side (S22, S24), and a simulated ring tone sounds (S106). This connects the external telephone 60 to the line via the second transmission path 13Cb and the second transmission path 13C, the second transmission path 13Db and the second transmission path 13D, via the resistor 15A and the photocoupler 16. Thus, if the incoming signal is not a CNG signal (S103: No), the external telephone 60 is not connected to the line via the resistor 15A and the photocoupler 16, and is not affected by the resistance of the resistor 15A.

[0080] In this state, the external telephone 60 is waited for to go off-hook. Specifically, it is determined whether the dumbbell ringing state has lasted for a predetermined timeout period T or longer (S107). If the predetermined timeout period T has expired (S107: Yes), fax communication is started (S108), and it is determined whether the other party is a fax sending terminal (S109).

[0081] Here, to determine whether the other party is a fax transmitting terminal, for example, a CED (Called Station Identification) signal indicating that the other party is a fax receiving terminal is sent to the transmitting side. If an incoming signal is received from the other party, the other party is determined to be a fax transmitting terminal. If the other party is determined to be a fax transmitting terminal (S109: Yes), the fax communication ends (S110). If the other party is not a fax transmitting terminal (S109: No), an error notification is issued, for example, via the operation display unit 47 (S111).

[0082] In step S107, if the handset goes off-hook before the predetermined timeout period T has elapsed (S107: No), it is determined whether the handset has been off-hook (S112) based on the current value detected by the photocoupler 16. If the handset has been off-hook (S112: Yes), the switch 17 is connected to the disconnection side (S21, S23), and the line signal receiving unit 22 of the semiconductor DAA 14 opens the telephone line network 50 (S113).

[0083] As a result, the external telephone 60 is connected to the line through the second transmission path 13Ca, the second transmission path 13C, the second transmission path 13Da, and the second transmission path 13D without passing through the resistor 15A and the photocoupler 16, and a call using the external telephone 60 is started (S114).

[0084] In this manner, when there is an incoming signal and the fax line is closed, if the incoming signal does not contain a CNG signal, it is highly likely that the call is being made, and the off-hook of the external telephone 60 is detected. However, by connecting the switch 17 to the on side (S22, S24), the resistor 15A connected to the second transmission path 13Db and the photocoupler 16 detect the current, and thus the off-hook of the external telephone 60 can be detected with high accuracy even when the line is closed.

Claims

1. A communication device comprising: a first connection portion connected to a telephone line network; a first path, which is a path from the first connection portion toward a modem located downstream of the telephone line network; a first detection unit, configured to detect a voltage of the first path; a second connecting portion, located downstream of the first connecting portion, the second connecting portion being connected to an external telephone; a second path, which is a path between the second connection portion and the first connection portion, and has resistance in the second path; a second detection unit configured to detect a current flowing in the second path; a switching unit, configured to switch the line to a non-connected state in which the line is not connected to the second detection unit when the line toward the modem is disconnected, and to switch the line to a connected state in which the line is connected to the second detection unit when the line toward the modem is closed; as well as A determination unit determines whether the external telephone is off-hook according to the detection result of the first detection unit in the non-connected state, and determines whether the external telephone is off-hook by the second detection unit in the connected state.

2. The communication device according to claim 1, wherein The determination unit determines that the external telephone is off-hook when the voltage between the first paths detected by the first detection unit changes beyond a predetermined threshold value.

3. The communication device according to claim 1 or 2, wherein: The second detection unit is a photocoupler, which detects the current flowing in the second path, wherein the photocoupler is composed of a light-emitting element and a phototransistor, the light-emitting element is connected in parallel with the resistor and emits light in response to the flow of current, and the phototransistor is turned on by the light emission of the light-emitting element.

4. The communication device according to claim 1 or 2, wherein: The communication device has a TEL / FAX automatic switching function for automatically switching between an external telephone and a fax function. The first detection unit performs line closing based on an incoming signal from the telephone line network. If the incoming signal includes a CNG signal indicating a fax sending terminal, fax communication is started. If the incoming signal does not include a CNG signal indicating a fax sending terminal, the switching unit switches to the connected state to determine whether the external telephone has been picked up. The communication device according to claim 3 , wherein: The communication device has a TEL / FAX automatic switching function for automatically switching between an external telephone and a fax function. The first detection unit performs line closing based on an incoming signal from the telephone line network. If the incoming signal includes a CNG signal indicating a fax sending terminal, fax communication is started. If the incoming signal does not include a CNG signal indicating a fax sending terminal, the switching unit switches to the connected state to determine whether the external telephone has been picked up.

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