EP1068386B1 - Device for wireless control of a sewing machine - Google Patents

Abstract

A wireless controlled switch (Figure 1) contained in a box (3) connected to the socket (2) of the sewing machine (1) by the plug (6) and fixed by two brackets (4 and 5) using screws (9). A speed selector (7) is incorporated to the box (3). An IEC mains supply lead can be connected to the mains socket (6). The wireless controlled switch (Figure 1) is activated by the wireless controller (12) (Figure 2) housed inside the box (10) with the lid (13) and the screws (14). The on-off switch (17) is operated by pressing the pad (15) which activates the spring (16). When the switch (17) is is on, a signal is transmitted from the wireless controller (12) to the controlled switch (Figure 1). The LED (18) indicates the state of the battery (19) that can be recharged by the means of a DC socket (11).

Description

This invention relates to a device to enable a sewing machine to be operated by the means of an in-house on-off switch that can be placed by the operator in a comfortable position allowing the user's hands and feet free.

It is well known that foot control users get pain in their knee joints.
Commonly with optical wireless foot controls any object that accidentally blocks the infrared beam causes malfunctions of the sewing machine.
Radio waves can be used instead but a coded signal should be used in order to prevent interferences with signals from other transmitters. A receiver of this type used in conjunction with a sewing machine motor malfunctions because of the interferences that occur between the low-level incoming signal from the transmitter and the high-level RFI (Radio Frequency Interference) created by the brush motor. Using a higher power for the transmitter could overcome the malfunction but it may damage the health of the operator using the device.

US-A-5 247 449 discloses a sewing machine having a wireless controller according to the pre-characterizing part of claim 1.

According to the present invention there is provided a device that can be used to operate a sewing machine without the need of a foot control allowing the operator to place an in-house on-off wireless controller switch in a comfortable position providing the user's hands free to hold the material and even people having restricted movement (eg in wheelchairs) can use the device. There is also provided a wireless controlled switch connected to the mains supply by by the means of a lead at one end and a connector to the sewing machine at the other end. A speed selector is placed on the controlled switch allowing the operator to manually select a convenient speed by the means of a switch (in fixed steps) or a potentiometer (continuously).
Another objects of the present invention is to prevent interferences from other sewing machines transmitters and overcome the problems of malfunction of the sewing machine's brush motor caused by the radio transmission method of operation although the incoming signal level from the transmitter is less than the RFI level created by the sewing machine brush motor. A very low power (no licence required) is used for the wireless controller, and more than one machine can be used independently and in the closest proximity to one another without interference from one transmitter to another thus permitting a number of sewing machines to be safely operated in a confined area. The controller switch is supplied with electric power by the means of a rechargeable battery and an LED shows the state of the battery. Once the LED light has gone out there will still be several hours of safety operation but the battery should be recharged in order to maintain its life-span.

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows the layout of the controlled switch of the device of the invention connected to a sewing machine

Figure 2 shows the controller of the device of Figure 1 and

Figure 3 shows the block diagrams of the device of Figure 1 and Figure 2.

Referring to Figure 1, the controlled switch is contained in a box 3 connected to the socket 2 of the sewing machine 1 by the plug 6 and fixed by two brackets 4 and 5 using screws 9. A speed selector 7 is incorporated to the box 3. An IEC mains supply lead can be connected to the mains socket 6.

Referring to Figure 2, the wireless controller 12 is housed inside the box 10 with the lid 13 and the screws 14. The on-off switch 17 is operated by pressing the pad 15 which activates the spring 16. When the switch 17 is on, a signal is transmitted from the wireless controller 12 to the controlled switch (Figure 1, position 3). The LED 18 indicates the state of the battery 19 that can be recharged by the means of a DC socket 11.

Referring to Figure 3, it shows the block diagrams of the invention. The wireless controller 1 comprises a power unit 3 supplying energy to the control unit 4 and the transmitter unit 6. A comparator 5 detects the state of the power unit 3 and shows it on an indicator 7. The power unit 2 can be recharged by the means of a DC power socket 2. The transmitter unit's carrier wave is AM pulse modulated by the control unit 4 also comprising a low frequency stabilised oscillator. The controlled switch 8 comprises a receiver 9 where the RF signal sent by the wireless controller 1 is amplified and mixed with the signal from a local oscillator and the resultant component amplified and fed to the filter 10. The output from the filter 10 is fed to the amplifier 11 then sent to the noise rejector 12 that allows only the expected signal to pass through the next stage amplifier 13. The output signal from 13 is fed to the demodulator 14 then amplified by the amplifier 15 that sends it to the opto-switch 16. The speed selector (manually set to a convenient speed) sends the incoming signal from the opto-switch 16 to the electronic switch 19 that allows the sewing machine's brush motor 18 to be activated.

Claims (1)

1. Wireless controlled switch for a sewing machine including a circuitry for rejection of the radio frequency interference created by the sewing machine's brush motor,by the brush motors of other sewing machines in the vicinity or by signal from wireless controllers of other sewing machines in the vicinity,wherein the transmitted signal is modulated in amplitude,wherein the speed selector is manually selected at a convenient speed in fixed steps by means of a switch or continuously by means of a potentiometer,having a rechargeable battery and led indicator to show when the battery should be charged characterized in that the wireless controlled switch(1) is contained in a box and comprises a power unit(3) which can be recharged by the means of a dc power socket(2) of the sewing machine.

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