AU749959B2

AU749959B2 - Line power arrangement for a telephone

Info

Publication number: AU749959B2
Application number: AU23824/99A
Authority: AU
Inventors: Dayantha Jayarathna; Gulden Leventler; Nagaraja Srikantashastry; Zhou Ran Tang; King Cheung Wong
Original assignee: Alcatel CIT SA; Alcatel SA
Current assignee: Alcatel Lucent SAS
Priority date: 1998-04-20
Filing date: 1999-04-16
Publication date: 2002-07-04
Anticipated expiration: 2019-04-16
Also published as: AU2382499A

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "LINE POWER ARRANGEMENT FOR A TELEPHONE" The following statement is a full description of this invention, including the best method of performing it known to us: This invention relates telephone subset equipment that includes calling line identification (CLI), and in particular to a power management arrangement which allows all normal telephone function operations and the CLI function operation, in the on-hook and off-hook modes, to be powered by current extracted from the exchange via the exchange line connected to the equipment.

With the introduction of sophisticated public switching equipment that can provide services such as CLI, the on-hook power requirements of telephone subsets connected to such public switching equipment has increased to a point where the current required to be bled from the exchange line to provide on-hook power, 10 exceeds the limit, typically 50pA, set by Telecom Authorities.

It is known to provide current to telephone subsets for on-hook functions by means of batteries or mains energized power-packs. A disadvantage in using batteries is that they require maintenance by the subscriber; another disadvantage is the environmental problem of disposing of used batteries. In the case of power- S: 15 packs, a disadvantage is that an AC power outlet is required in the vicinity of the S•telephone; another disadvantage is the relatively high cost of power packs.

It is an object of the present invention to provide a telephone arrangement that includes a power management means which meets the telephone's on-hook power requirements by utilizing current extracted from the exchange line to which S 20 the telephone is connected, without exceeding prescribed on-hook line current limits.

According to the invention, there is provided a telephone subset arrangement including a line terminal means for connexion to an exchange via an exchange line, rectifier bridge means across said line terminal means, a receiving means for receiving caller line identification data, a display means, a controllable switch means and a processor means, wherein said arrangement further includes a bleed circuit means arranged to extract, during said subset's on-hook mode, a predetermined level of current from said exchange line, said current providing energising power, via a first power rail, to said display means and a quiescent said processor means, and a bleed current regulator means and an associated storage capacitor means, whereby on reception of ring signal from said exchange, which contains calling line identification data between bursts of ring signal, said processor is switched to normal mode thereupon enabling, between said bursts of ring signal, said controlled bleed current regulator means which then charges said storage capacitor, said processor enabling said controllable switch means thereby applying current from said bleed current regulator means and said storage capacitor means via a second power rail, to said receiver means for reception of said caller line data, thereupon said processor disables said controllable switch means to disconnect said second power rail from said receiver means, and enables said display means to display calling line data.

In order that the invention may be readily carried into effect, an embodiment thereof will now be described in relation to the accompanying drawings in which S i Figure 1 shows a block schematic circuit of a telephone having a CLI function and incorporating a power management arrangement of the present invention; ••:Figure 2 shows a block schematic circuit of an impedance stabilising arrangement that may be incorporated in the arrangement shown in Figure 1.

15 Referring to the drawing, the arrangement includes line terminals L1 and L2; a bridge rectifier arrangement D1; a speech and ringer IC a bleed circuit a bleed current regulator a 3V regulator a CLI receiver a microprocessor a memory means a switch means a liquid crystal display and a storage capacitor (C1).

20 During idle mode, i.e. on-hook without ring signal, the 48 pA bleed circuit 2 •oooo will provide the necessary current to energise the telephone's liquid crystal display 8 to display message icons, and to keep the telephone's microprocessor 6 in quiescent mode. The voltage regulator 4 stabilizes the voltage of the bleed current, typically at 3.

During incoming ring, the telephone's speech IC 1 will detect the ring signal and activate the microprocessor 6 which will enable, between bursts of the ring signal, a 3 mA bleed current regulator 3 to charge a storage capacitor C1 before the CLI data arrives.

Preferably, at the same time, AC ring power, rectified by bridge rectifier D1, is delivered to Capacitor C1 via diode D2 to provide sufficient power for microprocessor 6 and the RAM (not shown) in LCD8, to reliably retain previously stored initialization data, in the event of a low voltage device, such as a modem or low voltage telephone, being connected in parallel across terminals L1 and L2.

The microprocessor 6 will close switch S1 to provide power to the CLI receiver just before the CLI data arrives. Upon receiving the CLI data the microprocessor 6 will switch off the CLI receiver 5 and switch on the LCD 8 to display the CLI message and write this message into the memory 7.

The storage capacitor C1 will provide extra power that cannot be provided by the current regulator 3 during CLI data reception.

To maximize the total power requirement for CL1 data reception, on receiving 10 the initial burst of ring signal which precedes the CL1 data, preferably the i microprocessor delays switching on the CL1 chip for a predetermined period, typically 500ms. After the delay period ceases the chip is switched on to receive the on-hook data that is contained in the period between the end of the initial burst of ring signal and the beginning of the first burst of cadenced ring signal.

15 When a modem is connected across terminals L1 and L2, excessive error rate of transmission from the modem can occur due to the fact that during the modem's training phase (load matching and equaliser training), the impedance presented by the telephone is high, but when the modem starts to subsequently transmit, the impedance presented by the telephone has changed to a relatively low value due to the behavior of capacitor C1.

S"In order to avoid the above mentioned transmission error rate, it is preferable to include the impedance stabilization arrangement shown in Figure 2. This latter arrangement comprises a negative voltage detector and a controlled discharge circuit, operatively connected to capacitor C1.

The negative voltage detector is activated when the voltage at V+ (Line Voltage) is below A control signal is sent to the discharge circuit which is enabled thereby. Once C1 is discharged to a voltage below V+ the negative voltage detector will be de-activated thereby removing the control signal and disabling the discharge circuit.

The arrangement accelerates the discharge of C1 so that it closely follows the line voltage and allows the final impedance of the telephone to stabilise before the training phase of the modem occurs.

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Claims

1. A telephone subset arrangement including a line terminal means for connexion to an exchange via an exchange line, rectifier bridge means across said line terminal means a receiving means for receiving caller line identification data, a display means, a controllable switch means and a processor means, wherein said arrangement further includes a bleed circuit means arranged to extract, during said subset's on-hook mode, a predetermined level of current from said exchange line, said current providing energising power, via a first power rail, to said display means and a quiescent said processor means, and a bleed current regulator means and an 10 associated storage capacitor means, whereby on reception of ring signal from said *exchange, which contains calling the identification data between bursts of ring signal said processor is switched to normal mode thereupon enabling between said bursts of ring signal, said controlled bleed current regulator means which then charges said storage capacitor, said processor enabling said controllable switch means 15 thereby applying current from said bleed current regulator means and said storage capacitor means via a second power rail, to said receiver means for reception of said caller line identification data, thereupon said processor disables said *o controllable switch means to disconnect said second power rail from said receiver means, and enables said display means to display calling line data. 20

2. A telephone subset arrangement as claimed in claim 1, including a voltage regulator means arranged to stabilise the voltage of said current from said bleed circuit means at a predetermined voltage magnitude.

3. A telephone subset arrangement as claimed in claim 1 or claim 2, wherein said rectifier bridge means output is coupled, via coupling means, to said storage capacitor means, whereby rectified AC ring signal current is delivered to said storage capacitor means.

4. A telephone subset arrangement as claimed in claim 3, wherein said coupling means includes a diode means. A telephone subset arrangement as claimed in any one of the preceding claims, further including an impedance stabilizing arrangement comprising a negative voltage detector means whose input means is coupled to said line terminal means and whose output means is coupled to control means of a controllable discharge circuit means connected across said storage capacitor means, whereby upon said negative voltage detector means detecting that the magnitude of a voltage at said line terminal means is less than the magnitude of a voltage across said storage capacitor means, said negative voltage detector means enables said controllable discharge circuit means to begin discharging said storage capacitor means, said controllable discharge circuit means being disabled when the magnitude of the voltage across discharging storage capacitor means falls below the magnitude of the voltage at said line terminal means. 10 6. A telephone subset arrangement, substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings. DATED THIS THIRTEENTH DAY OF APRIL, 1999 15 A TE reehdL5 Ccirk 5r,'hI eadl e 22dlG :T O