Facsimile storage and exchange system

Claims

What is claimed is:

1. A load distributing apparatus for a facsimile storage and exchange system comprising:

a plurality of facsimile units, each connected to respective ones of first lines, for transmitting and receiving information through said first lines;

a plurality of facsimile storage and exchange units, each including:

a communication control means connected to a plurality of second lines, for receiving image information and address information from one of said plurality of facsimile units through one of said second lines, and for transmitting said image information to at least another one of said facsimile units designated by said address information,

storage means for storing said received image and address information until said received image information is transmitted, and

a central control means for controlling said communication control means and said storage means; and

a communication exchange network for connecting said first lines to said second lines so as to enable transmission and reception of information between said facsimile units and said facsimile storage and exchange units, and for interconnecting said second lines so as to enable transmission and reception among said facsimile storage and exchange units;

wherein said central control means includes:

means for calculating a quantity of image information load to be processed in connection with communication of said image information stored in said storage means,

means for generating supervision information indicative of the quantity of image information load to be processed, for transmitting said supervision information generated at the facsimile storage and exchange unit containing the generating means via said communication exchange network to another facsimile storage and exchange unit and for receiving supervision information generated at said another facsimile storage and exchange unit via said communication exchange network, and

means for exchanging means information and address information among said facsimile storage and exchange units via said communication exchange network so that the quantity of image information load to be processed indicated by said supervision information for each of said facsimile storage and exchange units may be balanced.

2. A load distributing apparatus according to claim 1, wherein the quantity of image information load to be processed is calculated as .SIGMA. (the communicated quantity of image information items).times.(the frequency of appearances of the information items in a communication queue supervised by the central processing means)/(the number of communication lines used).

3. A load distributing apparatus for a facsimile storage and exchange system according to claim 1 wherein said central control means further includes:

means for causing, when said facsimile storage and exchange unit is out of order, information indicative of the out-of-order status of the facsimile storage and exchange unit to be included in said supervision information; and

means for transferring, safer completion of transmission of said supervision information from said communication control means to said another facsimile storage and exchange unit via said communication exchange network, said image information and address information stored after the completion of the transmission in said storage means from said storage means via said communication network to said another facsimile storage and exchange unit.

4. A load distributing apparatus for a facsimile storage and exchange system according to claim 1 wherein each of said facsimile exchange and storage units includes:

a joint memory for storing data; and

switching means for distributing said communication control units and for connecting said distributed communication control units to each of said central processing units,

wherein said communication control means includes a plurality of communication control units connected to said communication exchange network vai said second lines, and

wherein said central control means includes a main central processing unit and at least one sub central processing unit, for distributing image information and address information stored in said storage means, and for supervising said distributed image information and address information,

said main and sub central processing units each including means for preparing supervision data indicative of the number of said communication control units that are put under the control of each of said central processing units when connected to said communication control units via said switching means and for storing the supervision data in said joint memory,

said main control processing unit including means for calculating ht quantity of image information load to be processed of the main central processing unit based on the number of lines corresponding to the number of said communication control units under the control of said main central processing unit, the number of said communication control units indicated by said supervision data, and on a communication quantity of said image information and address information under the control of said main central processing unit, said image information being stored in said storage means, and for calculating the quantity of image information load to be processed of the sub central processing unit based on the number of lines corresponding to the number o said communication control units under the control of the sub central processing unit, said number of said communication control units being indicated by said supervision data, and on said image information and address information stored in said storage means under the control of the sub central processing unit, and

means for redistributing said communication control units to each of said central processing units by switching said switching means of that the quantity of image information load to be processed of said main central processing unit and that of said sub central processing unit may be balanced.

5. A load distributing apparatus for a facsimile storage and exchange system according to claim 4 wherein each of said central processing units includes:

means for causing, when one central processing unit is out of order, information indicative of the out-of-order status of said one central processing unit to be included in the supervision data; and

means for putting, when the out-of-order status of the another processing unit is shown by said supervision data stored in said joint member, communication control units under the control of said another central processing unit under the control of said central processing unit containing the putting means by switching h switching means.

6. A load distributing apparatus according to claim 4, wherein the quantity of image information load to be processed is calculated as .SIGMA.(the communicated quantity of image information items).times.(the frequency of appearance of the information items in a communication queue supervised by the central processing means)/(he number of communication lines used).

7. A load distributing apparatus for a facsimile storage and exchange system according to claim 1 wherein each of said facsimile exchange and storage units includes:

a joint memory for storing data; and

wherein said communication control means includes a plurality of communication control units connected to said communication exchange network via said second lines, and

wherein said central control means includes a main central processing unit and at least one sub central processing unit, for distributing image information and address information stored in said storage means, and for supervising said distributed image information and address information, as well as for distributing said communication control units and supervising said distributed communication control units,

said main and subs central processing units each including means for preparing supervision data indicative of the number of said communication control units that are put under the control of each of said central processing units when connected to said communication control units via said switching means in for storing the supervision data in said joint memory,

said main central processing unit including:

means for calculating the quantity of image information load to be processed of the main central processing unit based on the number of lines corresponding to the number of said communication control units under the control of said main central processing unit, the number of said communication control units indicated by said supervision data, and on a communication quantity of said image information and address information under the control of said main central processing unit, said image information being stored in said storage means, and for calculating the quantity of image information load to be processed of the sub central processing unit based on the number of lines corresponding to the number of said communication control units under the control of the sub central processing unit, said number of said communication control units being indicated by said supervision data, and on said image information and address information stored in said storage means under the control of the sub central processing unit, and

means for redistributing image information and address information stored in said storage means to each of said central processing units so that the quantity of image information load to be processed of said main central processing unit and that of said sub central processing unit may be balanced.

8. A load distributing apparatus for a facsimile storage and exchange system according to claim 7 wherein each of said central processing units includes:

means for causing, when one central processing unit is out of order, information indicative of the out-of-order status of said one central processing unit to be included in the supervision data; and

means for putting , when the out-of-order status of another processing unit is shown by said supervision data stored in said joint memory, all of said image information and address information stored in said storage means under the control of said central processing unit containing the putting means.

9. A load distributing apparatus according to claim 7, wherein the quantity of image information load to be processed is calculated as .SIGMA.(the communicated quantity of image information items).times.(the frequency of appearances of the information items in a communication queue supervised by the central processing means)/(the number of communication lines used).

10. A load distributing apparatus for a facsimile storage and exchange system comprising:

a plurality of facsimile units, connected to respective ones of first lines, for transmitting and receiving information through said first lines;

a facsimile storage and exchange unit including:

a plurality of communication control units connected to a plurality of second lines, for receiving image information and address information from one of said plurality of facsimile units through one of said second lines, and for transmitting said image information to at least one of another facsimile units designated by said address information,

storage means for storing said received image and address information until said received image information is transmitted,

a joint memory for storing data, and

a main central processing unit and at least one sub central processing unit, for distributing image information and address information stored in said storage means, and for supervising said distributed image information and address information, as well as for distributing said communication control units and supervising said distributed communication control units, and switching means for connecting said distributed communication control units to each of said central processing units; and

a communication exchange network for connecting said first lines to said second lines so as to enable transmission and reception of information between said facsimile units and said facsimile storage and exchange unit;

said main and sub central processing units each including means for preparing supervision data indicative of the number of said communication control units that are put under the control of each of said central processing units when connected to said communication control units via said switching means and for storing the supervision data in said joint memory,

said main central processing unit including:

means for calculating the quantity of image information load to be processed of the main central processing unit based on the number f lines corresponding 5.degree. the number of said communication control units under the control of said main central processing unit, the number of said communication control units indicated by said supervision data, and on a communication quantity of said image information and address information under the control of said main central processing unit, said image information being stored in said storage means, and for calculating the quantity of image information load to be processed of the sub central processing unit based on the number of lines corresponding to the number of said communication control units under the control of the sub central processing unit, said number of said communication control units being indicated by said supervision data, and on said image information and address information stored in said storage means under the control of the sub central processing unit, and

means for redistributing said communication control units to each of said central processing units by switching said switching means so that the quantity of image information load to be processed of said main central processing unit and that of said sub central processing unit may be balanced.

11. A load distributing apparatus for a facsimile storage and exchange system according to claim 10 wherein each of said central processing units includes:

means for causing, when one central processing unit is out of order, information indicative of the out-of-order status of said cone central processing unit to be included in the supervision data; and

means for putting, when the out-of-order status of the another processing unit is shown by said supervision data stored in said joint memory, communication control units under the control of said another central processing unit under the control of said central processing unit containing the putting means by switching the switching means.

12. A load distributing apparatus for a facsimile storage and exchange system according to claim 10 wherein said main central processing unit includes:

means for redistributing image information and address information stored in said storage means to each of said central processing units to that the quantity of image information load to be processed of said main central processing unit and that of said sub central processing unit may be balanced.

13. A load distributing apparatus according to claim 12, wherein the quantity of image information load to be processed is calculated as .SIGMA.(the communicated quantity of image information items).times.(the frequency of appearances of the information items in a communication queue supervised by the central control unit)/(the number of communication lines used).

14. A load distributing apparatus for a facsimile storage and exchange system according to claim 10 wherein each of said central processing units includes:

means or causing, when one central processing unit is out of order, information indicative of the out-of-order status of said one central processing unit to be included in the supervision data; and

means for putting, when the out-of-order status of another processing unit is shown by said supervision data stored in said joint memory, all of said image information and address information stored in said storage means under control of said central processing unit containing the putting means.

15. A load distributing apparatus according to claim 10, wherein the quantity of image information load to be processed is calculated as .SIGMA.(the communicated quantity of image information items).times.(the frequency of appearance of the information items in a communication queue supervised by the central control unit)/(the number of communication lines used).

16. A load distributing apparatus for a facsimile storage and exchange system comprising:

a plurality of facsimile units, connected to respective ones of first lines, for transmitting and receiving information through said first lines;

a facsimile storage and exchange unit including:

a plurality of communication control units connected to a plurality of second lines, for receiving image information and address information from one of said plurality of facsimile units through one of said second lines, and for transmitting said image information to at least one of another facsimile units designated by said address information,

storage means for storing said received image and address information until said received image information is transmitted,

a joint memory for storing data, and

a main central processing unit and at least one sub central processing unit, for distributing image information and address information stored in said storage means, and for supervising said distributed image information and address information, as well as for distributing said communication control units and supervising said distributed communication control units; and

a communication exchange network for connecting said first lines to said second lines so as to enable transmission and reception of information between said facsimile units and said facsimile storage and exchange unit;

said main and sub central processing units each including means for preparing supervision data indicative of the number of said communication control units that are put under the control of each of said central processing units and for storing the supervision data in said joint memory,

said main central processing unit including:

means or calculating the quantity of image information load to be processed of the main central processing unit based on the number of lines corresponding to the number of said communication control units under the control of said main central processing unit, the number of said communication control units indicated by said supervision data, and on a communication quantity of said image information and address information under the control of said main central processing unit, said image information being stored in said storage means, and for calculating the quantity of image information load to be processed of the sub central processing unit based on the number of lines corresponding to the number of said communication control units under the control of the sub central processing unit, said number of said communication control units being indicated by said supervision data, and on said image information and address information stored in said storage means under the control of the sub central processing unit, and

means for redistributing image information and address information stored in said storage means to each of said central processing units so that ht quantity of image information load to be processed of said main central processing unit and that of said sub central processing unit may be balanced.

17. A load distributing apparatus for a facsimile storage and exchange system according to claim 16 wherein each of said central processing units includes:

means for causing, when one central processing unit is out of order, information indicative of the out-of-order status of said one central processing unit to be included in the supervision data; and

means for putting, when the out-of-order status of another processing unit is shown by said supervision data stored in said joint memory all of said image information and address information stored in said storage means under the control of said central processing unit containing the putting means.

18. A load distributing apparatus according to claim 16, wherein the quantity of image information load to be processed is calculated as .SIGMA.(the communicated quantity of image information items).times.(the frequency of appearances of the information items in a communication queue supervised by the central control unit)/(the number of communication lines used).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a load distributing apparatus for a facsimile storage and exchange system which stores image information from a facsimile unit and transmits the stored image information to a facsimile unit.

2. Description of the Related Art

In a conventional facsimile storage and exchange system, a plurality of storage and exchange units are disposed dispersively at corresponding positions, each of the storage and exchange units having a plurality of facsimile units allocated thereto and supervised thereby. If a facsimile unit transmits image information and destination information for that image information to its storage and exchange unit, the storage and exchange unit receives and stores the image and destination information, and relays the image and destination information to a further storage and exchange unit to which a facsimile unit represented by the destination information is allocated. When the further storage and exchange unit receives and stores the image and destination information, it transmits the image information to the facsimile unit represented by the destination information and supervised by the further storage and exchange unit.

Since the respective storage and exchange units supervise their allocated facsimile units separately, if the respective numbers of facsimile units supervised by the storage and exchange units are unbalanced, the quantities of information communicated among the storage and exchange units will be unbalanced. In order to cope with this situation, each storage and exchange unit is arranged to have slightly more than enough communication lines to process possible congestion with some leeway to thereby adjust the number of facsimile units supervised by that storage and exchange unit. Alternatively, the number of facsimile units supervised may be limited. Since, however, the number of facsimile units supervised by the corresponding storage and exchange unit cannot be changed according to the circumstances, there has been the problem that the quantities of information communicated or the respective loads on the storage and exchange units will be unbalanced. If a problem occurs in one storage and exchange unit, it is difficult for another storage and exchange unit to take over and supervise the facsimile units supervised separately in place of the former defective storage and exchange unit.

On the other hand, a single storage and exchange system may supervise many facsimile units in a concentrated manner. Such a storage and exchange system has, for example, a plurality of central processing units (hereinafter referred to as CPUs) as a control device, each CPU supervising a plurality of allocated facsimile units separately. However, if the respective numbers of facsimile units supervised by the corresponding CPUs are unbalanced, the respective loads on the CPUs will be unbalanced. Thus either each CPU supervises enough communication lines to cope with congestion or the number of facsimile units that may be supervised by one CPU is limited. Thus, problems arise because some of the communication lines are wasted or because the capability of the respective CPUs is not made the best of.

OBJECT AND SUMMARY OF THE INVENTION

It is, therefore, an object of this invention to provide a load distribution apparatus for a facsimile storage and exchange system that balances loads on a plurality of storage and exchange units and that balances loads on a plurality of control devices in one facsimile storage and exchange unit.

In a first aspect of this invention, there is provided a load distributing apparatus for a facsimile storage and exchange system, comprising communication control means for controlling receipt of image information via communication lines; storage means for storing image information; and central processing means for receiving image information from a facsimile unit via the communication control means, storing the received image information into the storage means, and transmitting the stored image information to other facsimile units via the communication control means, wherein the central control means creates supervision information indicative of a quantity of image information load to be processed, exchanges the supervision information with other facsimile storage and exchange units, and exchanges image information with other facsimile storage and exchange units on the basis of the load control information such that the quantities of image information load to be processed by the central processing means and the facsimile storage and exchange units are balanced.

According to the first aspect of this invention, the respective supervision information items are exchanged among at least two facsimile storage and exchange units and image information items are then exchanged among the respective facsimile storage and exchange units such that the quantities of image information load to be processed are balanced among the facsimile storage and exchange units on the basis of those supervising information items. Therefore, the quantity of an image information will not partially be loaded heavily on any particular storage and exchange unit.

In a second aspect of this invention, there is provided a load distributing apparatus for a facsimile storage and exchange system, comprising a plurality of communication control devices corresponding to communication lines, each of the communication control devices being adapted to control receipt of image information via the communicating lines; storage means for storing image information; a plurality of central processing units each allocated to the corresponding communication control devices for storing into the storage means image information received from facsimile units, and transmitting the stored image information to other facsimile units; the apparatus further including a joint memory accessed by the respective central processing units; and switching means for connecting the communication control device selected by a central processing unit to same such that the communication control device is put under supervision of that central processing unit; the respective central processing units creating supervision data for image information and storing the data in the joint memory; and the central processing units calculating the respective quantities of image information load to be processed thereby, and switching the switching means such that the numbers of communication control devices put under supervision of the corresponding central processing units are averaged on the basis of the calculated quantities of image information load and the respective supervision data items stored in the joint memory.

According to the second aspect of this invention, the switching means is switched such that the respective numbers of communication control devices supervised by the CPUs are averaged on the basis of the respective quantities of load to be processed by the CPUs and the supervision data stored in the joint memory. Therefore, the image information load to be processed by one central processing unit will not partially be increased.

In a third aspect of this invention, there is provided a load distributing apparatus for a facsimile storage and exchange system, comprising: communication control means for controlling receipt of image information via communication lines; storage means for storing image information; and a plurality of central processing units for receiving image information from a facsimile unit via the communication control means, storing the received image information into the storage means, and transmitting the stored image information to other facsimile units via the communication control means; wherein the plurality of central processing units calculate the corresponding quantities of image information load to be processed thereby, and exchange image information among the respective central processing units such that the quantities of image information load to be processed are balanced.

According to the third aspect of this invention, the respective quantities of load to be processed by the central processing units are balanced by exchanging image information among the respective CPUs. Therefore, the load on one CPU will not partially be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a facsimile storage and exchange system including a first embodiment of this invention.

FIG. 2 is a flowchart showing the operation of the system of FIG. 1.

FIG. 3 is a block diagram of a facsimile storage and exchange system involving another embodiment of this invention.

FIG. 4 is a flowchart showing the operation of the system of FIG. 3.

FIG. 5 is a flowchart showing the operation of still another embodiment of this invention.

FIG. 6 is a block diagram of a communication control device in a storage and exchange unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of this invention will now be described in more detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a facsimile storage and exchange system including a first embodiment of a load distributing apparatus according to this invention. In this embodiment, a plurality of facsimile units 1-1 to 1-n are connected via communication lines 2-1 to 2-n to a communication network 3. A plurality of storage and exchange units 4-1 to 4-m are connected to communication network 3 via the corresponding communication line groups 5-1 to 5-m. Storage and exchange units 4-1 to 4-m include communication control devices (CCEs) 6-1 to 6-m connected to the corresponding communication line groups 5-1 to 5-m, central processing units (CPUs) 7-1 to 7-m, which control the corresponding storage and exchange units 4-1 to 4-m, and storages 8-1 to 8-m, such as disks, which store various information items.

Each of communication control devices 6-1 to 6-m has a structure, shown in FIG. 6, composed of a plurality of communication units 65-1 to 65-q. Each communication unit includes a network control circuit (NCU) 61, a modem 62, a communication control unit 63 and an image conversion unit 64. Network control circuit 61 can be connected to any one of the communication lines of the communication line group to control connection of that line. When modem 62 receives a signal indicative of image information via network control unit 61, the modem demodulates the signal to form image data, which is then transmitted to communication control unit 63. When modem 62 receives image data from communication control unit 63, it modulates the image data to form a signal indicative of image data. The signal is then transmitted to a line via network control circuit 61. Communication control unit 63 executes transmission control procedures, for example, for a G-3 machine obeying CCITT Recommendation with a facsimile unit via network control circuit 61 and modem 62. Network control circuit 61 exchanges image data with modem 62, image conversion unit 64, and the CPU. Image conversion unit 64 compresses and encodes image data receiving from a facsimile unit to provide data having a shortened length to thereby reduce the quantity of image information to be stored. Image conversion unit 64 expands and encodes the image data to adjust the data format to a facsimile unit to which the data is to be transmitted. Image conversion unit 64 reduces or enlarges an image or converts the image line density, as desired. Such a communication unit is provided for each communication line. Thus if a communication control device includes, for example, twelve communication units, it can handle twelve circuit lines.

If, for example, facsimile unit 1-1 calls storage and exchange unit 4-1, they are connected via communication network 3. Facsimile procedure signals are transmitted and received between facsimile unit 1-1 and communication control device 6-1 in storage and exchange unit 4-1. Facsimile unit 1-1 then transmits destination information (a secondary address) and image information. The destination information designates the facsimile to which the image information is to be transmitted.

Unit 4-1 inputs the destination and image information via communication control device 6-1 to CPU 7-1, which then stores the destination and image information items in storage 8-1 in corresponding relationship.

CPU 7-1 reads the destination and image information items from storage 8-1 as needed. If the destination information designates, for example, facsimile unit 1-2, CPU 7-1 calls the destination facsimile 1-2 to which the image information is to be transmitted via control device 6-1 and transmits the image information to facsimile unit 1-2 via communication control device 6-1.

As described above, each of facsimile units 1-1 to 1-n transmits destination and image information items to each of storage exchange units 4-1 to 4-m and the transmitted destination and information items are stored in the respective storages 8-1 to 8-m of storage and exchange units 4-1 to 4-m. Each of the storage and exchange units 4-1 to 4-m transmits image information to a facsimile unit designated by the destination information.

In the described embodiment, in order to eliminate unbalance between quantities of image information to be processed by the respective storage and exchange units, processing according to the flowchart of FIG. 2 is performed.

First, for example, CPU 7-1 of storage and exchange unit 4-1 calls storage and exchange unit 4-m via communication control device 6-1 each time a predetermined preset time is reached (step 101). Thus when storage and exchange units 4-1 and 4-m are connected via communication network 3, CPUs 7-1 and 7-m of storage and exchange units 4-1 and 4-m are capable of transmitting/receiving data therebetween.

When the preset time is reached, CPU 7-1 of storage and exchange unit 4-1 then directs storage and exchange unit 4-m to report to unit 4-1 the quantity of image information load per communication line (hereinafter referred to as the QLC) to be processed by unit 4-m (step 102). CPU 7-1 calculates the QLC to be processed by storage and exchange unit 4-1 in accordance with the following formulas (1) and (2) (step 103). If the quantity of each of the image information items stored as a queue in storage 8-1 of storage and exchange unit 4-1 is a communication quantity, the load on the storage and exchange unit 4-1 will be given by the following formula;

.SIGMA.(communication quantity of an image information item).times.(frequency of appearances in the queue of the image information item)

Namely, the load represented by formula (1) is the sum of communication quantities for image information communicated for each request for communication.

If the communication lines of communication line group 5-1 connected to storage and exchange unit 4-1 are used, the QCL to be processed by storage and exchange unit 4-1 is substantially given by

K.sub.1 =.SIGMA.(communication quantity of image information item).times.(frequency of appearances in the queue of the image information item) / (the number of communication lines used)

When CPU 7-m of storage and exchange unit 4-m is directed to report the QLC to be processed by storage and exchange unit 4-1 at step 102, it calculates QLC km processed by storage and exchange unit 4-m on