GB2231467A

GB2231467A - Network controller

Info

Publication number: GB2231467A
Application number: GB9009134A
Authority: GB
Inventors: Masaharu Iida
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1989-04-27
Filing date: 1990-04-24
Publication date: 1990-11-14
Anticipated expiration: 2010-04-24
Also published as: JP2820955B2; JPH02288436A; GB2231467B; GB9009134D0; DE4013420A1; DE4013420C2

Description

2 2:3 X -11 GS, -7 1 "NETWORK CONTROLLER" 1 The present invention

generally relates to network controllers and more particularly to a network controller wherein setting of circuit constants can-be made easily.

is Communication facilities such as facsimile apparatus or computers which perform communications with other facilities via a communication network generally use a network controller for establishing connections or for setting up of calls.

At present, the procedure of establishing the connections or setting up the calls may be different country by country or area by area, and because of this, the circuit constants of the network controller have to be changed depending on the area or country in which the communication facility is used. When the network controller is designed and manufactured for each of the area, the cost needed for manufacturing the network controller and thus the cost for manufacturing the communication facility is increased intolerably.

In order to avoid this problem, the conventional network controller employs a 1 construction wherein the network controller has an identical construction. only the circuit constants are changed by,changing the setting of a jumper.

FIG.1 shows a typical example of such a conventional network controller.

Referring to FIG.1 showing a prior art network controller 1 used in a facsimile apparatus, the network controller 1 is connected to a line L forming the network via a relay 2 which selectively connects the line L to either of a telephone set 3, a call detection circuit 4, or a d.c. loop formation circuit 5. A modem 7 is connected to the d.c. loop formation circuit 5 via a transformer 6. The call detection circuit 4 comprises capacitors 8 and 9, resisters 10 - 14, Zener diodes 15 and 16, a photocoupler 17 and the like, and produces a detection signal RING in response to a detection of the call transmitted along the line L by the photocoupler 17. The call detection circuit 4 connects either the capacitor 8 or the capacitor 9 to the line L in response to the placement of a jumper 18 or a jumper 181 and thus, the capacitance component of the call detection circuit 4 is - 4 determined by the setting of the jumper 18 or jumper 181. Similarly, the resistance component of the call detection circuit 4 is determined by a jumper 20 or a jumper 201. Further, the d.c. loop formation circuit 5 comprises a relay 21 and a resister 22, and forms a d.c. loop when the relay 22 is closed. The resistance of the d.c. loop formation circuit 5 is changed by placing or removing a jumper 23.

In the conventional network controller 1 described heretofore, it is generally practiced that a service personnel changes the setting of the jumpers 18, 181 or jumpers 20, 201 in response to the area or country in which the facility is to be used.

In the foregoing network controller 1, however, there is a problem in that the setting of the jumpers has to be made by human intervention after the manufacturing of the network controller 1 is completed. Such a process is costly and take a considerable time. Thereby, the competitiveness of the communication facility is reduced.

Accordingly, it is a general object of the present invention to provide a novel and useful -R - network controller wherein the problems described heretofore are eliminated.

is A more specific object of the present invention is to provide a network controller having a construction which is identical irrespective of the area in which the network controller is to be used, wherein the setting of circuit constants of the network controller in response to the area in which the network controller is to be used is made by reading out a control data from a memory in correspondence to an area code indicative of the area, and the setting of the circuit constants can be made automatically in response to the input of the area code. According to the present invention, the setting of the circuit constants of the network controller can be made easily in a simple procedure. Thereby, the manufacturing cost of the network controller is significantly reduced.

According to the present invention, there is provided a network controller adapted for connection to a network selected from a plurality of networks of different types, said network controller being interposed between a selected network and a 1 is communication apparatus for establishing a connection therebetween, said network controller having a predetermined circuit constant determined in response to the type of the selected network to which the network controller is connected, comprising: connection supporting means adapted for physical connection with the selected network and coupled to the communication apparatus, for establishing the connection between the network and the communication apparatus, said connection supporting means providing the predetermined circuit constant of the network controller; memory means for storing a plurality of control data each specifying the circuit constant of the network controller in correspondence to an area code specifying a geographical area; processing means supplied with an area code specifying one of the geographical areas in which the network controller is to be used, for reading out the control data corresponding to the area code supplied thereto from the memory means; and circuit constant modification means supplied with the control data from the processing means for changing the circuit constant in response to the network control data supplied thereto. According to the present invention, the circuit constant of the network controller can be 1 adjusted by a simple procedure.

In a preferred embodiment of the present invention, the connection supporting means comprises a direct current loop formation circuit connected to the network for forming a direct current loop in the connection supporting means such that the direct current loop is connected to the network with a predetermined resistance, wherein the circuit constant modification means changes the resistance of the direct current loop in response to the network control data.

In another preferred embodiment of the present invention, the connection supporting means comprises a call detection circuit connected to the network in the connection supporting meansfor detecting calls incoming from the network, said call detection circuit having a predetermined resistance and a predetermined capacitance, wherein the circuit constant modification means changes the resistance and capacitance of the call detection circuit in response to the control data.

Other objects and further features of the present invention will become apparent from the following detailed description when read in conjunction with the attached drawings.

FIG.1 is a circuit diagram showing an example of a conventional network controller; FIG.2 is a block diagram showing a facsimile apparatus in which the network controller according to an embodiment of the present invention is used; FIG.3 is a detailed circuit diagram showing the network controller of FIG.2; FIG.4 is a diagram showing a structure of an area code used in the network controller of FIG.2; and FIG.5 is a diagram showing a structure of a network control data used in the network controller of FIG.2.

Hereinafter, the present invention will be described with reference to an embodiment shown in FIGS.2 - 5.

FIG.2 shows a block diagram of a facsimile apparatus 31 in which the network controller 1 according to the first embodiment of the present invention is used. Referring to FIG.2, the facsimile apparatus 31 comprises a central processing unit (CPU) 32, a read-only-memory (ROM) 33, a random access memory (RAM) 34, an input/display unit 35, an I/0 port 36, a modem 37, a facsimile unit 38 and a network controlunit 39 which forms an essential part of the present invention, wherein the ROM 33 stores a fundamental control program-for controlling the ordinary operation of the facsimile apparatus and further a second control program for controlling the network control unit 39 as will be described. The CPU 32 controls the facsimile apparatus 31 in accordance with the fundamental control program in the ROM 33 such that the facsimile apparatus 31 performs a predetermined sequence of facsimile transmission and reception. Further, the CPU 32 controls circuit constants of the network control unit 39 according to the second control program stored in the ROM 33. The control of the circuit constants of the network control unit 39 forms the essential part of the present invention. The RAM 34 stores various data necessary for the operation of the facsimile apparatus 31 as well as area codes and control data which are used in the control of the 1 is circuit constants of the network control unit 39, as will be described later. The input/display unit 35 comprises a keyboard and a display unit as usual, and is used for inputting a telephone number of a destination station to which a facsimile transmission is to be made as well as for inputting the area code which specifies the area or country in which the facsimile apparatus 31 is to be used. The display unit may be a liquid crystal display device and displays various informations for an operator operating the facsimile apparatus. The modem 37 performs modulation and demodulation of a carrier, and the facsimile unit 38 performs scanning of an image on a sheet for producing a facsimile signal to be transmitted, printing a received image on a sheet, coding and decoding of the facsimile signals, and communication control of the facsimile signals, as usually practiced.

FIG.3 shows the network control unit 39. Referring to FIG.3, the network control unit 39 comprises a relay 41, a direct current (d.c.) loop formation circuit 42, a call detection circuit 42 and a transformer 44, and performs operations such as establishment of connection between the facsimile -,4 1 apparatus 31 and a line L forming a part of the network, detection of calls coming in from the network along the line L, and the like. The relay 41 is controlled by the CPU 32 and selectively connects one of the d.c. loop formation circuit 42 and the call detection circuit 43 to the line L. Further, a telephone set 45 is connected to the call detection circuit 43 such that the telephone set 45 is connected to the line L when the call detection circuit is connected to the line L by the relay 41.

The d.c. loop formation circuit 42, in turn, comprises a relay RY1, a diode bridge DBl, resistors R1 and ri, a photocoupler PC1 and the like, and forms a d.c. loop connected to the line L when the relay RY1 is closed under the control of the CPU 32. The diode bridge DBl is connected so as to bypass the resistor R1. The photocoupler PC1 comprises a light emitting diode (LED) D1 and a phototransistor Trl optically coupled with the LED D1, and the diode bridge DBl is connected to the phototransistor Tri in conformity with respect to the direction of the current. The LED DI is energized in response to a drive signal S1 supplied from the CPU 32 with a logic level 1, and in response to the 1 energization of the LED1, the transistor Trl is turned on. When the transistor Trl is turned on, the resister Rl is,shorted by the diode bridge DBl, and the d.c. loop is formed along a path connecting the relay 41, the relay RY1, the diode bridges DBl, the photocoupler PC1, the transformer 44, and returning to the relay 41. Thereby, the resister Rl is bypassed by a bypass circuit which is provided by the diode bridge DBl. When the drive signal S1 has the logic level 0 under the control of the CPU 32, the bypass circuit across the resister Rl is opened and the d.c. loop is formed along a path connecting the relay 41, the relay RY1, the resister Rl, the transformer 44, and returning to the relay 41.

The call detection circuit 43 comprises capacitors Cl and C2, diode bridges DB2 and DB3, photocouplers PC2 - PC7, resistors R2 - R5, r2 - r5, and Zener diodes ZD1 and ZD2, and performs a detection of a call coming in along the line L. It should be noted that the capacitors Cl is connected in series with the diode bridge DB2, the capacitor C2 is connected in series with the diode bridge DB3, and the capacitors Cl and C2 are connected parallel to the line L when the diode bridges DB2 and DB3 are turned on. The diode bridges DB2 and DB3 are further connected to phototransistors Tr2 and Tr3 respectively, wherein the phototransistor Tr2 is coupled optically with an LED D2 to form the photocoupler PC2, and the phototransistor Tr3 is coupled optically with an LED D3 to form the photocoupler PC3. The LEDs D2 and D3 are energized respectively in response to drive signals S2 and S3 which are supplied from the CPU 32 with the logic level 1, and in response to the energization of the LED D2 by the drive signal S2, the transistor Tr2 is turned on and the diode bridge DB2 is caused to turn on. As a result, the capacitor Cl is connected parallel to the line L. On the other hand, when the drive signal S2 has the logic level 0 in response to the control of the CPU 32, the parallel connection of the capacitor Cl is opened. Similarly, when the LED D3 is energized in response to the drive signal S3 having the logic level 1, the transistor Tr3 is turned on and the diode bridge DB3 is caused to turn on. Thereby, the capacitor C2 is connected parallel to the line L. When the drive signal S3 has the logic level 0, the parallel connection of the capacitor C2 to the line L is opened.

1 It should be noted that the resisters R2 and R3 are connected in series to the capacitors Cl and C2 respectively. Further, the photocoupler PC4 is connected so as to bypass the resister R3. The photocoupler PC4 comprises an LED 4 which is energized in response to a drive signal S4 supplied from the CPU 32 with the logic level 1 and a phototransistor Tr4 coupled optically to the LED 4. When the LED 4 is energized in response to the drive signal S4, the transistor Tr4 is turned on and a bypass circuit bypassing the resister R3 is formed by the transistor Tr4. on the other hand, when the LED 4 is deenergized in response to the drive signal S4 assuming a deenergized state, the bypass circuit across the resister R3 is opened.

The resisters R4 and R5 are connected parallel with respect to a circuit part comprising the photocoupler PC7 used for the detection of calls and the Zener diodes ZD1 and M2 connected in series to the Zener diodes ZD1 and ZD2. Further, the photocouplers PC5 and PC6 are connected in series to the resisters R4 and R5 respectively. The photocoupler PC5 comprises an LED 5 energized by a drive signal S5 supplied from the CPU 32 with the 1 logic level 1 and a phototransistor Tr5 coupled optically to the LED 5. In response to the drive signal S5 from.the CPU 32, the transistor Tr5 is turned on and the resister R4 is connected parallel to the circuit part comprising the photocoupler PC7 and the Zener diode W1, ZD2. On the other hand, when the drive signal S5 has the logic level 0, the resister R4 is disconnected. Similarly, the photocoupler 6 comprises an LED D6 energized by a drive signal S6 from the CPU 32 with the logic level 1 and a phototransistor Tr6 coupled optically to the LED D6. The resister R5 and the transistor Tr6 are connected in series and forms a circuit part connected parallel to the circuit part comprising the serial connection of the photocoupler PC7 and the Zener diodes ZD1 and ZD2. Thus, when the drive signal S6 is supplied from the CPU 32 with the logic level 1, the transistor Tr6 is turned on in response to the turning on of the LED D6 and the resister R5 is connected parallel to the circuit part comprising the photocoupler PC7 and the Zener diodes W1 and W2. When the drive signal S6 is deenergized. the resister R5 is disconnected. The photocoupler PC7 comprises an LED D7 driven in response to the call and a phototransistor Tr7 which is optically coupled - 16 to the LED D7 for producing a detection signal RING indicating detection of the call.

Next, the operation of the network control unit 39 which is pertinent to the present invention will be described. According to the present invention, setting of the circuit constants can be made automatically in correspondence to the type of the network to which the facsimile apparatus is to be connected. It should be noted that the different type of the network requires different circuit constants for the network control unit, and the type of the network is different in area by area or country by country.

As already described, the facsimile apparatus 31 includes the RAM 34, and the RAM 34 stores a list of areas in which the facsimile apparatus 31 may be used, in a form of area code. FIG.4 shows an example of such an area code. In the example of FIG.4, each of the area codes A1 - A4 is formed from a data having four bits. These area code may reprdsent countries imposing different standards for the communication network. These area codes A1 - A4 are stored in the RAM 34. "4 1 1 When setting up the circuit constants, the area code specifying the area in which the facsimile apparatus 31 is to be used is inputted via the input/display unit 35 at the time of delivering the facsimile apparatus. Alternatively, the setting of the area code may be changed at the time of setting up the facsimile apparatus at the station where it is to be used, by inputting the area code corresponding to the station via the input/display unit 35.

More specifically, the facsimile apparatus 31 is set to operate in a mode ready for setting the circuit constants by the key operation of the input/display unit 35. Next, the area code corresponding to the area in which the facsimile apparatus 31 is to be used is inputted. In response thereto, the CPU 32 searches the control data stored in the RAM 34 on the basis of the area code thus inputted, and produces drive signals S1 - S6 on the basis of the searched control data.

FIG.5 shows an example of the control data stored in the RAM 34. As shown therein, the control data comprises a data table listing a number of binary data in correspondence to the area code, 1 is wherein each bit of the binary data indicates on or off of the drive signal S1 - S6. Thus, the control data is determined in one to one correspondence to the area code, and the CPU 32 produces the drive signals S1 - S6 in response to the control data. As already described, the driv e signals S1 - S6 energize the photocouplers PC1 - PC6, and the setting of circuit constants of the network control unit 39 is achieved.

In the case of the d.c. loop formation circuit 42, the setting of the circuit constants is made as follows. Assuming that the d.c. resistance of the transformer 44 is 150 - and further assuming that the statutory prescribed value of the d.c. resistance of the d.c. loop formation circuit 42 is in the range of 400 - - 600 - in a country A, the drive signal S1 is set to the logic level 0 as shown in FIG.5 in correspondence to the area code A1 specifying the country A, and the bypass circuit across the resister R1 is opened. Thereby, the resister R1 is connected in series to the transformer 44 and the statutory prescribed resistance of the foregoing range is satisfied. In the case of another country such as a country B wherein the statutory prescribed resistance of the d.c. loop formation circuit 42 is in the range of 120 - 300 _, on the other hand, the,drive signal S1 is set to the logic level 1 in response to an area code A2 specifying the country B, and the bypass circuit across the resister R1 is closed as a result. Thereby, the resistance of the d.c. loop formation circuit 42 becomes identical to the resistance of the transformer 44. Thus, the foregoing prescribed value of the resistance for the country B is satisfied in response to the energization of the drive signal S1.

Next, the setting of the circuit constants for the call detection circuit 43 will be described. It should be noted that the statutory prescribed value of the capacitance, impedance and level of call detection are different depending on the area or country. Assuming that a country C prescribes the capacity to be equal to or less than 0.5 _F, the impedance to be equal to or larger than 8 k_ but equal to or smaller than 20 k-, and that the detection level to be equal to or larger than 40 Vrms, these requirements are met by setting the drive signal S2 to the logic level 0, the drive signal S3 to the logic level 1, the drive signal S4 to the 1 logic level 1, the drive signal S5 to the logic level 1, and the drive signal S6 to the logic level 0. In response to the foregoing settings, the photocoupler PC2 is turned-off, the photocoupler PC3 is turned on, the photocoupler PC4 is turned on, the photocoupler PC5 is turned on, and the photocoupler PC6 is turned off. Thereby, the capacitance of the call detection circuit 43 is determined by the capacitor C2, and the impedance thereof is determined by the capacitor C2 and the resister R2. The detection level is determined by the resister R4.

When the facsimile apparatus 31 is used in another country such as a country D wherein the call detection circuit 43 is required to have the capacity of 1.0 -F +/- 20 %, the impedance of 30 k_ or more, and the level of call detection of 15 Vrms or more, the drive signal S2 is set to have the logic level 1, the drive signal S3 is set to have the logic level 0, the drive signal S4 is set to have the logic level 0, the drive signal S5 is set to have the logic level 0, and the drive signal S6 is set to have the logic level 1. In response to the foregoing setting for the country D, the photocoupler PC2 is turned on, the photocoupler PC3 is turned off, the photocoupler PC4 is turned off, the photocoupler PC5 is turned off, and the photocoupler PC6 is turned on. Thereby, the capacitance is.determined by the capacitor Cl, the impedance is-determined by the capacitor Cl, the resister R2 and the resister R3, and the detection level is determined by the resister RS.

As described heretofore, the setting of the circuit constants of the network controller can be achieved easily and simply, and associated therewith, the time needed for adjusting the circuit constants can be substantially reduced.

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Claims

CLAIMS.

1. A network controller adapted for connection to a network selected from a plurality of networks of different types, said network controller being interposed between a selected network and a communication apparatus for establishing a connection therebetween, said network controller having a predetermined circuit constant determined in response to the type of the selected network to which the network controller is connected, comprising: connection supporting means adapted for physical connection with the selected network and coupled to the communication apparatus, for establishing the connection between the network and the communication apparatus, said connection supporting means providing the predetermined circuit constant of the network controller; memory means for storing a plurality of control data each specifying the circuit constant of the network controller in correspondence to an area code specifying a geographical area; processing means supplied with an area code specifying one of the geographical areas in which the network controller is to be used, for reading out the control data corresponding to the area code supplied thereto from 4 1 the memory means; and circuit constant modification means supplied with the control data from the processing means for changing the circuit constant in response to the network control data supplied thereto.

2. A network controller as claimed in claim 1 in which said circuit constant modification means comprises a switching circuit connected to a passive circuit element which determines the predetermined circuit constant, the switching circuit is connected so as to close a circuit connected to the passive circuit element in response to the control data.

3. A network controller as claimed in claim 2 in which said passive circuit element comprises a resister, and said switching means comprises a photocoupler comprising a phototransistor and a light emitting device optically coupled to the phototransistor. said phototransistor being connected in series to the resister, said light emitting device being supplied with the control data and driven in response to the control data, said phototransistor being closed in response to an energization of the light emitting device by the control data.

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4. A network controller as claimed in claim 2 in which said passive circuit element comprises a resister, said switching means comprises a diode bridge and a photocoupler controlling the diode bridge, said photocoupler comprising a phototransistor and a light emitting device optically coupled to the phototransistor, said diode bridge being connected so as to form a bypass circuit across the resister, said light emitting device being supplied with the control data and driven in response to the control data, said phototransistor controlling the diode bridge such that the bypass circuit across the resister is closed in response to an energization of the light emitting device by the control data.

5. A network controller as claimed in claim 2 in which said passive circuit element comprises a capacitor, said switching means comprises a diode bridge and a photocoupler controlling the diode bridge, said photocoupler comprising a phototransistor and a light emitting device optically coupled to the phototransistor, said diode bridge being connected in series to the capacitor and forming a serial circuit to the capacitor, said light 1 emitting device being supplied with the control data and driven in response to the control data, said phototransistor controlling the diode bridge such that the serial circuit is closed in response to an energization of the light emitting device by the control data.

6. A network controller as claimed in claim 1 in which the connection supporting means comprises a direct current loop formation circuit connected to the network for forming a direct current loop in the connection supporting means such that the direct current loop is connected to the network with a first predetermined resistance, wherein the circuit constant modification means changes the resistance of the direct current loop from the first predetermined resistance to a second predetermined resistance in response to the network control data.

7. A network controller as claimed in claim 1 in which the connection supporting means comprises a call detection circuit connected to the network in the connection supporting means for detecting calls incoming from the network, said call detection circuit having a predetermined resistance and a t, 1 predetermined capacitance, wherein the circuit constant modification means changes the resistance and capacitance. of the call detection circuit in response to the control data.

8. A network controller described with reference to Figure'3 of the accompanying drawings.

1 Published 1990 atThe Patent Office. State House. 66?l. High Rolborn. London WC1R 4TP. Purther copies maybe obtainedfrom The PatentOfrice. Sales Branch, St Mary CrAY. Orpington. Kent BES 3RD. Printed by Multiplex techiuques ltd, St Mary Cray, Kent. Con. 1187