DE2905982B2 - Facsimile receiver with multiple access - Google Patents

Description

The invention belongs to the field of facsimile signal transmissions. It particularly relates to a facsimile receiver that has multiple telephone lines are assigned and can receive multiple facsimile messages at the same time, each in the form of a Document should be output. Such systems are called facsimile receivers with multiple access.

From DE-AS 12 59 623 a facsimile receiver is known, which optionally and successively with one of multiple transmission lines can be connected. So it needs a central transmission control system to prevent two or more

Lines receive information at the same time.

The DE-AS19 11 338 shows on the other hand how on a Transmission path several transmission channels can be formed in time division multiplex. On the Emps On the catch side, i.e. behind a demultiplexer, there must then be as many ready-to-use receivers as Transmission channels are available.

The object of the invention is to provide a facsimile receiver to train so that several transmitters at the same time

ίο can transmit information without a central control system for the coordination of the transmitter or a large number of receivers is required. These The object is achieved by the receiver characterized in claim 1 with regard to features

preferred embodiments of the invention is shown on referenced the subclaims.

The invention is described below using an exemplary embodiment with reference to the figure explained in more detail

Multiple phone lines, here n = 3, designated 1, 2 and 3, a facsimile receiver are assigned to this recipient has a document printing device 5 which received on its input facsimile signals generated starting copy of a document In addition, the receiver comprises π line circles, with 7, 8 and 9, each of which establishes the connection of the receiver's circuits to a telephone line is in communication via the line terminal 10. The line terminal 10 matches the facsimile receiver in terms of potentials and its impedance to the telephone line and provides for the galvanic separation between the telephone line and the facsimile receiver circuits. The circuit 10 is a known and standardized interface module. The control logic 11 detects the incoming call signals from the associated telephone line. It allows the exchange of information between the facsimile receiver and the calling party before any facsimile signals are received from the telephone line, in order to determine and establish the operational readiness of the receiver. The demodulator 12 then receives the signals coming from the telephone line and demodulates them.

The other management circuits 8 and 9 correspond to management circuit 7.

The output of the demodulator 12 of each of the line circuits 7, 8 and 9 leads via an access control circuit 16 to a memory 15. This access control circuit 16 is a circuit with η inputs and a single output which is connected to the input of the memory 15 the role of the multiplex circuit for the demodulated signals to be introduced into the memory. The access control circuit 16 is itself controlled by a write / read control circuit 17 which manages the memory content.

For this purpose, this control circuit 17 is connected to each of the line circuits 7 to 9 and receives from the management circuits to determine the call signals coming from the assigned telephone lines and allows or denies the connection of one of the lines to the receiver depending on the Willingness to save the received signals. These functions are carried out through a bidirectional link between the control circuit 17 and each of the

Circuits 7 to 9 indicated The read / write control circuit 17 also determines, depending on the specified bit frequency on each telephone line, for example 2400 bits per second, and on the number of times at the receptions :; connected Lines the number of signals to be received in the memory 15 and consequently delivers to the Access control circuit 16 to which it is connected to the suitable multiplex clock for the signals received from the lines and to be stored supplies the read-write control circuit 17 to the Store the consecutive addresses for storing the incoming signals accordingly the number of incoming signals.

The way of storing the signals given to the input of the memory is shown by the control circuit 17 determines the storage of the signals coming from a telephone line can in a be carried out by a sequence of addresses determined area by the control circuit 17 the is advantageously assigned signals originating from the telephone line connected at the time the facsimile signals are transmitted in compressed form on the various telephone lines. They are also stored in compressed form in memory 15 Memory 15 is connected to the printing device via a decoder assigned to two output registers 21 and 22 20 connected.

The task of the decoder 20 is to transform the signals present in compressed form in the memory into other signals that can be used directly in the printing device 5. So if the compression of the phone lines transmitted signals in a coding of the lengths of zones of the same degree of blackening Analysis signals of the original document and / or in some other coding is used by the Decoder performed the reverse conversion to that used when analyzing the original document to recover generated signals that are identical to signals. For this decoding of the registered in the memory The decoder "calls" signals to restore each corresponding document in memory 15 registered signals, while the control circuit 17, which is also connected to the decoder, the successive output addresses of the memory with the query speed of the decoder Restoring the registered signals corresponding to a document is determined. The memory is therefore determined also at the variable speed provided by the decoder and under the supervision of the circuit 17 emptied which specifies the addresses for this emptying

With the aid of the two registers 21 and 22, the signals coming from the decoder 20 can be output by the printing device 5 at the restoration speed of the document. These two registers are selected so that their capacity corresponds to the content of a document line, ie the number of scanning points per line of the document, eo The two registers 20 and 21 are alternately switched to the filling position by the decoder Passing through a given counting state corresponding to the number of scanning points per line of the document is alternately switched to the emptying state. For this purpose, the said counter 23 is acted upon by a clock generator, not shown here, belonging to the printing device, with signals HI indicating the scanning speed of the successive scanning points of a line of the Deliver the document. Thus, one of the registers 21 and 22 is filled with a variable speed, starting from the decoder, while the other register is emptied at a constant speed determined by the printing device 5.

With the facsimile receiver according to the invention can thus be used by several participants at the same time incoming facsimile signals are received, with the documents corresponding to them subsequently can be printed out one after the other by a single high-speed printer. The memory 15 therefore performs a Intermediate storage of the incoming facsimile signals from different telephone lines by, while the assigned control circuit 17 the sequence of the documents to be produced from these signals certainly

The storage capacity of the memory 15 is selected as a function of the number of accesses by the receiver, although the capacity does not have to be exactly proportional to this number. If, for example, the content of a document in compressed form is about 10 ⁵ to 4 · IO ⁵ bits, then a memory with a capacity of about 5 · 10 ⁵ bits is chosen if the receiver according to the prior art only has a single access or a single access Telephone line having this capacity, for example, on 4 × 10 ⁵ bits for the reception of the document being transmitted and 10 ⁵ bits for the beginning of the reception of the following document to be transmitted during the printing phase of the document that has already been transmitted. In contrast, in a receiver according to the invention with multiple access, the capacity of the memory can be limited to 7.5 · 10 ⁵ bits if the receiver has two accesses and to 10 ⁶ bits for a receiver with three accesses. This possibility of using a memory with a capacity that is not proportional to the number of accesses is explained on the one hand by the fact that the transmitted documents only require full capacity in exceptional cases and on the other hand by the fact that the reading time of the stored signals corresponding to a document is transmitted through the printing time is determined (about 20 seconds for a xerographic printer) is significantly less than the time required to write into the memory the signals corresponding to the content of a transmitted signal; this writing time depends on the bit volume of the transmitted document and on the transmission capacity of the telephone line or the processing capability of the demodulator and is about one minute if a modem with 4800 bits per second is used.

1 sheet of drawings

Claims (3)

Patent claims: 1. Facsimile receiver with multiple access based on π telephone lines assigned to it, where η is at least equal to 2 and the recipient has a printing device for printing out copies of several documents sent simultaneously based on the facsimile signals received simultaneously on the different lines, characterized in that this printing device ( 5) is designed for the sequential reproduction of the various documents and that π line circuits (7,8,9), each a line terminal (10), a demodulator (12) and a control logic (11) for monitoring the reception of the relevant Telephone line (1, 2, 3)! Incoming facsimile signals, and a memory (15) are provided, the capacity of which is greater than the content of a document to be reproduced and the demodulator (12) of each of the π line circuits (7,8,9 ) with the memory (15) connecting access control circuit (16} with η inputs and an output and a read-write control circuit (17) for filling and emptying is assigned to the successive addresses for filling the memory (15) in time with the telephone lines by the access control circuit (16) received and the successive addresses for emptying the memory (15) Reproduction of the facsimile signals corresponding to a document in the printing device (5) is determined 2. The facsimile receiver of claim 1, wherein the facsimile signals received from the lines present in compressed form, characterized in that the connected by the Lines received facsimile signals are registered in compressed form in the memory (15) and that the receiver also has one with the memory (15) and the read / write control circuit (17) connected decoding circuit (20) from the memory with variable processing speed of the decoder receives signals supplied and two output registers (21, 22) alternately loads that alternately queried by the printing device at constant playback speed will. 3. Receiver according to one of claims 1 and 2, characterized in that the capacity of the memory (15) is chosen so that it is able to store less than η documents at the same time.