AU2002224658B8 - Device for preventing loss of high frequency signals - Google Patents

Description

Editorial Note: 2002224658 Standard Patent There are four pages in the Description WO 02/058269 PCT/AU02/00052 DEVICE FOR PREVENTING LOSS OF HIGH FREQUENCY SIGNALS Field of the Invention This invention relates to devices that allow transmission of high frequency signals through remote power supplies associated with electronic appliances or equipment.

Background of the Invention Some electronic appliances and equipment are powered by remote power supplies.

Typical examples are appliances such as facsimile machines, telephone answering machines, and cordless telephones which are powered by AC adaptors that convert the AC mains power into either AC or DC outputs at various voltages, typically from six (6) to fifteen (15) volts.

In general, remote power supplies contain a transformer with or without a rectifier, or a switch mode power supply, or other componentry or circuitry which performs an equivalent power conversion function, that usually blocks the transmission of high frequency signals.

The functions of some electronic appliances or equipment are dependent upon high frequency signals received through the incoming mains power supply. Consequently, when a remote power supply or other device, eg. a line filter or uninterruptable power supply, is interposed between the mains power supply and the appliance or equipment, the high frequency signals are severely attenuated by the power conversion circuitry in the remote power supply or other device. This renders inoperative those functions in the appliance or equipment which are dependent on the high frequency signals.

Summary of the Invention The invention provides a device to prevent loss of high frequency signals transmitted over a power supply system to an appliance or other electronic equipment powered by a remote power supply incorporating power conversion circuitry which blocks high frequency signals, including first means providing a high frequency signal path to bypass the power conversion circuitry, and second means for coupling the high frequency signal bypassed by the first means to the output of the remote power supply Brief Description of Drawings Figures 1 to 3 are circuit diagrams illustrating remote power supplies incorporating preferred circuitry embodying the invention.

1 SUBSTITUTE SHEET (RULE 26) ROIAU WO 02/058269 PCT/AU02/00052 Description of Preferred Embodiments The system embodying the invention includes high frequency electronic circuitry and componentry, such as detailed in Figures 1 to 3, integrated with and typically installed in the same housing or enclosure as, the power conversion circuitry of the remote power supply. This circuitry and componentry is designed to allow high frequency signals picked up from the incoming mains power supply side of a remote power supply to be transmitted to an appliance or equipment connected to the output of the remote power supply, without attenuation or interference. The high frequency signals received at the appliance or equipment are decoded and used to perform the functions which are dependent on these signals. Remote power supplies fitted with this high frequency electronic circuitry and componentry are also compatible with appliances or equipment which do not require high frequency signals picked up from the mains power supply.

Figure 1 illustrates the circuitry and componentry of one preferred embodiment of a remote power supply fitted with high frequency detection and coupling circuitry. The power conversion circuitry 1 may consist of a transformer with or without an output rectifier, or a switch mode power supply, or other circuitry to perform an equivalent function and which would block the passage of high frequency signals. High frequency signals on the incoming supply are detected and coupled to the output by means of high frequency circuitry 2, comprising transformer T1, capacitors Cl and C3, and high frequency choke LI. The input voltage 3 is applied via connectors CON1 and CON2 and the output is obtained via connectors- CON3, CON4 and (optional) CON5. The output-4 of the remote power supply, with superimposed high frequency signals, is connected to the appliance or other electronic equipment via output socket connectors CON3 and CON4. Alternatively, the output of the remote power supply minus high frequency signals may be obtained via connectors CON4 and CON5. In the latter case, the high frequency signals may be obtained via connectors CON3 and CON5, or via connectors CON3 and CON4. This alternative 3-wire output connection avoids the need for additional componentry and circuitry at the appliance or other electronic equipment to separate the high frequency signals from the output of the remote power supply. The primary winding of transformer T1, and capacitor C1 form a series resonant circuit tuned to the centre frequency of the high frequency signals. The secondary winding of transformer TI is used as a sensing winding, which replicates the high frequency signals flowing in the primary winding of transformer T1. Because of the resonant circuit formed by T1 primary and capacitor C1, signals at the resonant frequency (ie the desired signals) are accentuated, while signals at other frequencies (eg noise) are attenuated.

The output level of the high frequency signals is set by the turns ratio of transformer T1.

Transformer T1 also maintains electrical- isolation between the incoming power supply and the low voltage output of the remote power supply. Capacitor C3 is provided to prevent the output current of the remote power supply flowing through the secondary winding of transformer T1 when the optional 3-wire connection is not used, which could cause saturation of the core, and adversely affect transformer action. High frequency choke L1 provides a low impedance path for the output of the remote power supply while presenting a high impedance to the high frequency signals, thus ensuring effective transmission of the high frequency signals to the appliance. Appropriate circuitry and componentry in the appliance are used to separate the high frequency signals from the output of the remote power supply.

2 SUBSTITUTE SHEET (RULE 26) ROIAU WO 02/058269 PCT/AU02/00052 Figure 2 illustrates the circuitry and componentry of a second preferred embodiment of a remote power supply fitted with high frequency detection and coupling circuitry. The power conversion circuitry 1 may consist of a transformer with or without an output rectifier, or a switch mode power supply, or other circuitry to perform an equivalent function and which would block the passage of high frequency signals. High frequency signals on the incoming supply are detected and coupled to the output by means of high frequency circuitry 2, comprising transformer T1 and capacitor C1. The input voltage 3 is applied via connectors CONI and CON2 and the output 4 is obtained via connectors CON3, CON4 and (optional) CON5.. The output of the remote power supply, with superimposed high frequency signals, is connected to the appliance or other electronic equipment via output socket connectors CON3 and CON4. Alternatively, the output of the remote power supply minus high frequency signals may be obtained via connectors CON4 and CON5 utilising the optional 3-wire connection shown. In the latter case, the high frequency signals may be obtained via connectors CON3 and CON5, or via connectors CON3 and CON4. This alternative 3-wire connection avoids the need for additional componentry and circuitry at the appliance or other electronic equipment to separate the high frequency signals from the output of the remote power supply. The primary winding of transformer TI, and capacitor Cl form a series resonant circuit, tuned to the centre frequency of the high frequency signals. The secondary winding of transformer T1 is used as a sensing winding, which replicates the high frequency signals flowing in the primary winding of transformer T1. Because of the resonant circuit formed by T1 primary and capacitor C1, signals at the resonant frequency (ie the desired signals) are accentuated,-while signals-at other frequencies (eg noise) are attenuated.

The output level of the high frequency signals is set by the turns ratio of transformer T1.

Transformer T1 also maintains electrical isolation between the incoming power supply and the low voltage output of the remote power supply. Transformer T1 is so designed that when the optional 3-wire connection is not used, its secondary winding can carry the full rated output current of the remote power supply without causing core saturation, which would adversely affect transformer action. Appropriate circuitry and componentry in the appliance are used to separate the high frequency signals from the output of the remote power supply when the optional 3-wire connection is not used.

Figure 3 illustrates the circuitry and componentry of a third preferred embodiment of a remote power supply fitted with high frequency detection and coupling circuitry. The power conversion circuitry 1 may consist of a transformer with or without an output rectifier, or a switch mode power supply, or other circuitry to perform an equivalent function and which would block the passage of high frequency signals. High frequency signals on the incoming supply are detected and coupled to the output by means of high frequency circuitry 2, comprising transformer T1 and capacitors Cl and C3. The input voltage 3 is applied via connectors CONI and CON2 and the output 4 is obtained via connectors CON3 and CON4. The output of the remote power supply, with superimposed high frequency signals, is connected to the appliance or other electronic equipment via output socket connectors CON3 and CON4. The primary winding of transformer T1, and capacitor C1 form a series resonant circuit, tuned to the centre frequency of the high frequency signals. The secondary winding of transformer T1 is used as a sensing winding, which replicates the high frequency signals flowing in the primary winding of transformer T1. Because of the resonant circuit formed by T1 primary and capacitor Cl, signals at the resonant frequency (ie the desired signals) are accentuated, while signals at other frequencies (eg noise) are attenuated.

3 SUBSTITUTE SHEET (RULE 26) ROIAU WO 02/058269 PCT/AU02/00052 The output level of the high frequency signals is set by the turns ratio of transformer T1.

Transformer T1 also maintains electrical isolation between the incoming power supply and the output of the remote power supply. Capacitor C3 prevents current from the output of the power conversion circuitry flowing through the secondary winding of transformer T1 and possibly causing saturation of the core, which would adversely affect transformer action. Appropriate circuitry and componentry in the appliance are used to separate the high frequency signals from the output of the remote power supply.

Claims (4)

1. A device to prevent loss of high frequency signals transmitted over a power supply system to an appliance or other electronic equipment powered by a remote power supply incorporating power conversion circuitry which blocks high frequency signals, including first means providing a high frequency signal path to bypass the power conversion circuitry, and second means for coupling the high frequency signal bypassed by the first means to the output of the remote power supply

2. The device of Claim 1, wherein the first means includes a high frequency transformer, and at least one capacitor configured as a resonant circuit to detect and couple the high frequency signal to the output of the remote power supply.

3. The-device of Claim 2, wherein the high frequency transformer is such that core saturation cannot occur at current outputs up to the maximum rated output current of the remote power supply.

4. The device of Claim 2, further including a further capacitor connected to prevent the output current of the remote power supply flowing through the secondary of the high frequency transformer, and a choke connected to provide a low impedance path for the output current of the adaptor, while presenting high impedance to the high frequency signals. The device of Claim 2, configured as a three-wire output device such that the output of the power conversion circuitry and the high frequency signals are electrically independent at the device, and no additional circuitry or componentry are required at the appliance or equipment to separate the high frequency signals from the output of the power conversion circuitry. 4 SUBSTITUTE SHEET (RULE 26) ROIAU