GB2624497A

GB2624497A - An improved retrofit switching assembly

Info

Publication number: GB2624497A
Application number: GB2312400.1A
Authority: GB
Inventors: Churchward Mark
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-18
Filing date: 2021-05-18
Publication date: 2024-05-22
Also published as: GB202312400D0

Abstract

A printed circuit board (PCB) 1 for retrofitting to a device without a power switch, by interposing it between a power cell 2 and the power cell contacts of a device 3, the PCB 1 comprising a timer 6, a motion sensor 7, a controller and an electronic switch 4. The switch 4 is controlled to connect the power cell 2 to the power cell contacts 3 if the motion sensor 7 indicates that the PCB 1 has been moved. The switch 4 is further controlled to disconnect the power cell 2 from the power cell contacts 3 if the timer 6 and the motion sensor 7 indicate that the PCB 1 has not been moved for a predetermined time. The PCB 1 may be flexible, suitable for wrapping around a power cell 2. Alternatively, the PCB 1 may be rigid, suitable for receiving and partially enclosing a power cell 2. The assembly reduces power consumption when the device 3, such as a children’s toy or a keyless entry fob for a vehicle, is not in use.

Description

An improved retrofit switching assembly Field of the invention [1] The invention relates to a switching circuit. In particular, the nvention relates to a motion activated switching circuit, which can be retrofitted to devices 5 which use squat cylinder-type batteries, such as so-called button cells or coin cells.

Background of the invention

[2] There are many battery-powered devices which do not provide on-off switches, but which do not need to be powered all the time. For example, many toys fin children are powered by batteries to play music or light up when motion is detected nearby. These toys may go untouched for days or weeks on end, while their sensors are continuously drawing power from the batteries.

[3] In some cases, there arc disadvantages to battery powered devices being powered all the time, beyond the simple waste of energy.

[4] For example, modern motor vehicles are often fitted with keyless entry systems. Such vehicles can be unlocked and their engines started in response to a user's fob device being detected nearby. These systems can be vulnerable to relay hacking, wherein a relay system relays and records signals between a vehicle and a key fob. This enables an unauthorised person to open and start a vehicle, without the authorised fob. Fobs are only vulnerable to hacking, when their transceiver circuits are powered, and Sc) it would be advantageous to power them only when they are in use.

[5] EP0984124 describes an electronic key for a motor vehicle that comprises a switch to prevent transmission of an identification signal from the key.

[6] US2006/0238296 describes a key for a motorbike that comprises an off switch.

[007] US2016/0365739 describes a battery interrupter that allows a user to retro-fit an on-off switch to a device which was not originally provided with such a switch.

Summary of the invention

H081 A first aspect of the irivention provides a printed circuit board (PCB) comprising: an electrical insulator having a first side and a second, opposite side; a control circuit disposed on the electrical insulator; the control circuit comprising a controller, a timer, a motion sensor, and an electronic switch having first and second terminals and a control input; the control circuit further comprising a first electrical terminal and a second electrical terminal for connecting the control circuit to a source of electrical power; the printed circuit board further comprising a first electrically conductive layer on the first side, and a second electrically conductive layer on the second side; the first electrically conductive layer comprising a first contact pad and a second contact pad; and the second electrically conductive layer comprising a third contact pad and a fourth contact pad; the first and second electrically conductive layers further comprising: a first electrically conducting trace between the first contact pad and the third contact pad; a second electrically conducting trace between the second contact pad and the first terminal of the electronic switch; a third electrically conducting trace between the first contact pad and the first electrical terminal of the control circuit; A fourth electrically conducting trace between the second contact pad and the second electrical terminal of the control circuitry; and a fifth electrically conducting trace between the second terminal of the electronic switch and the fourth contact pad; wherein the controller is configured to cause the electronic switch to switch to an 'on' state when the motion sensor detects movement of the printed circuit board, and is further configured to cause the electronic switch to switch to an 'off' state when the motion sensor has not detected movement of the printed circuit board for a predetermined period.

V109] Such an arrangement allows a user to interpose the PCB between a power cell of a device and the power cell contacts of the device. Thus, the device will be powered when it is moved, and will no longer be powered when it has not been moved for a predetermined period. Motion is indicative of the device being in use, and so when the device has not been in motion for a predetermined period, this is taken as an indication that the device is no longer in use. The invention may therefore prolong the life of a power cell by disconnecting it when the device is not in use.

L0101 In some embodiments, the electrical insulator may be a flexible electrical insulator having a first enlarged portion and a second enlarged portion, with a narrower bridge portion between the first and second enlarged portions. The first contact pad may be disposed on first side of the first enlarged portion. The second contact pad may be disposed on the first side of the second enlarged portion. The third contact pad may be disposed on the second side of the first enlarged portion.

The fourth contact pad may be disposed on the second side of both the second enlarged portion and the bridge portion.

Loll] In some such embodiments, the electrical insulator may be sized so as to wrap around a conventional button or coin cell, such that the first side of the first enlarged portion covers at least part of the negative terminal of the cell, and the first side of the second enlarged portion covers at least part of the planar element of the positive terminal of the cell.

[12] A flexible embodiment such as this can be wrapped around a power cell in use, particularly a coin or button power cell. It takes up very little space and fits neatly between the power cell and the power cell terminals of the device.

[13] In some such embodiments, the electrical insulator may be made from a synthetic polymer material, such as biaxially-oriented polyethylene terephthalate.

[14] In other embodiments, the flexible electrical insulator has a first enlarged portion and a narrow portion extending from the first enlarged portion, and wherein: the first side of the first enlarged portion is bonded to an outer face of a rigid planar circular member which has an annular rim protruding from its inner side; the control circuit is disposed on the first side of the first enlarged portion; a plurality of slots are provided in the outer face of the rigid planar circular member to receive and accommodate the control circuit components protruding from the first side of the first enlarged portion; the first contact pad is disposed on the first side of the first enlarged portion; a conductive via protrudes from the first contact pad, through the rigid planar circular member to its inner side; the second contact pad is disposed on the first side of the narrow portion; the third contact pad is disposed on the second side of the first enlarged portion; and the fourth contact pad is disposed on the second side of the narrow portion.

[15] In some such embodiments, the rigid planar circular member is sized so as 20 to substantially cover the negative terminal of a conventional coin or button cell.

[16] In some such embodiments, the narrow portion extends perpendicularly from the first enlarged portion of the flexible electrical insulator, beyond the annular rim, and then extends substantially parallel to and in the same direction as the first enlarged portion.

[017] Such embodiments provide a very compact cap which sits, in use, on top of the power cell, fitting within the power cell slot of the device. This makes the circuit board much easier to install. Preferably, the cap is no wider than the cell, but will increase the depth of the cell/circuit board assembly. For this reason, a smaller cell may be needed to fit into the device when the cap is used.

[18] In some embodiments, the motion sensor may be an accelerometer.

[19] In some embodiments, the electronic switch may comprise at least one transistor.

[20] Tn some embodiments, the electrically conductive layers may be made of conductive metal materials.

[21] In some embodiments, the predetermined period may be less than one minute, for example twenty seconds.

[022] In some embodiments, the controller may measure the time for which it has been in continuous use, and store the time in continuous use in non-volatile memory storage in the controller, from where it can be retrieved by a suitable reader device. The time in continuous use is stored in a predetermined format, for example, as a number of days. This is useful in certain contexts, such as in car key fobs, to prove that the device has been continuously powered throughout a given period in the event of a claim. It may also be useful to provide information about the last time the device was serviced. A transceiver may be included in the circuitry so that this information can be retrieved easily.

Brief description of the drawings

[023] Particular embodiments of the invention will now be described, by y of example only, with reference to the following drawings: [24] Figure 1 depicts a simplified circuit diagram of an embodiment of the invention.

[25] Figure 2 depicts a flexible circuit board according to a first embodiment of 25 the invention.

[26] Figure 3 depicts a flexible circuit board according to a second embodiment of the invention.

Detailed description

[27] The invention provides a retrofit automatic con/off functionality to devices which did not originally have such functionality. It does this by interposing a P03 between the power cell (particularly a coin or button power cell) and power cell contacts of a device, which is switched on and off in response to signals from a motion sensor and a timer.

[28] Figure 1 shows an exemplary simplified circuit diagram of the invention, in which a PCB 1 of the invention is interposed between a cell 2 and a circuit 3 of a device.

[29] The PCB 1 comprises an electronic switch 4 and a control module 5. The 15 control module 5 comprises a timer 6, a motion sensor 7, and a processor 8. The processor may comprise a memory storage clement, such as a non-volatile storage element.

[03(1] The motion sensor 7 may be an accelerometer.

[031] The electronic switch 4 may comprise one or more transistors.

[032] Although the control module 5 is depicted as a single unit, this is not necessary. The components of the control module may be distributed around the PCB 1.

[033] The processor 8 receives signals from the motion sensor 7 and the time 6 Based on these signals, the processor sends a signal to the switch 4, instructing it to either switch to an on-state or an off-state.

[34] Tf the processor 8 receives a signal from the motion sensor 7 indicating that the PCB 1 is in motion, it instructs the electronic switch 4 to switch to an on-state, since motion is indicative that the device is in use.

[35] If the processor 8 receives information from the motion sensor 7 and the 5 timer 6 indicating that the PCB 1 has not been moved for a predetermined time, it instructs the electronic switch 4 to switch to an off-state, since a prolonged lack of motion is indicative that the device is not in use.

[36] The predetermined time can be selected depending on the intended use. In a preferred embodiment, the predetermined time is less than sixty seconds, for 10 example twenty seconds.

[37] The processor 8 may record information relating to the duration of continuous operation of the PCB 1. For example, the processor may record information relating to the time that has elapsed since the PCB 1 was connected to a source of electrical power.

[038] The PCB 1 comprises a plurality of conductive surface dements disposed on an electrically insulating material, which form the circuits of the device. The conductive surface elements include contact pads for making electrical contact, in use, with the terminals of a power cell, and the power cell contacts of a device.

[39] A first contact pad 9 is disposed on the PCB 1 so as to make electrical 20 contact, in use, with the negative terminal of a power cell.

[40] A second contact pad 10 is disposed on the PCB 1 so as to make electrical contact, in use, with the positive terminal of a power cell.

[41] A third contact pad 11 is disposed on the PCB 1 so as to make electrical contact, in use, with the positive power cell contact of a device.

[042] A fourth contact pad 12 is disposed on the PCB 1 so as to make electrical contact, in use, with a negative power cell contact of a device.

[43] The conductive surface elements of the PCB 1 further comprise circuit traces for connecting circuit components.

[44] A first trace 13 is disposed between the first contact pad 10 and the third contact pad 11.

[0451 A second trace 14 is disposed between the second contact pad 9 and a first terminal 15 of the electronic switch 4.

[46] A third trace 16 is disposed between the first contact pad 10 and a first power terminal 17 of the control module 5.

[47] A fourth trace 18 is disposed between the second contact pad 9 and a 10 second power terminal 19 of the control module 5.

[48] A fifth trace 20 is disposed between a second terminal 21 of the electronic switch 4 and device terminal 12.

[49] There are two preferred embodiments of the invention: a flexible embodiment which wraps around a coin or button cell in use, and a rigid cap' 15 embodiment in which a coin or button cell is held in use.

[50] An example of the first embodiment is shown in Figure 2. The electrical insulator in this embodiment is a flexible film which is wrapped around a coin or button cell in use.

[51] The flexible film may be made from a synthetic polymer, such as biaxially20 oriented polyethylene terephthalate (commonly known by the trademark 1\4)Tlar 0).

[52] The conductive surface elements may be made of a conductive metal material, and are disposed on both sides of the flexible film. Where a circuit trace needs to move from one side to the other, for example to bypass another circuit trace, or to connect contact pads on opposing sides, conductive vias are provided through the flexible film to achieve this.

[53] The flexible film has a first enlarged portion 22 and a second enlarged portion 23, which are connected by a relatively narrow neck 24.

[54] The first contact pad 9 is disposed on a first side of the first enlarged portion 22. The second contact pad 10 is disposed on the first side of the second 5 enlarged portion 23.

[55] The third contact pad 11 is disposed on the second side of the second enlarged portion 23.

[56] The fourth contact pad 12 is disposed on the second side of the first enlarged portion 23 and bridge 24. This is because some devices have contact terminals to engage with the planar clement of the positive terminal of a coin or button cell (the base of the cell), whereas other devices have contact terminals to engage with the annular element of the positive terminal of a coin or button cell (the edge of the cell).

10571 Elements of the control module 5 are preferably disposed on the bridge 24.

[058] Figure 3 is an exploded view of an example of the second embodiment. The flexible electrical insulator has a first enlarged portion 25 and a narrow portion 26 extending from the first enlarged portion 25. The first side of the first enlarged portion 25 is bonded to an outer face of a rigid planar circular member 27, a cap', having a small annular rim protruding from its inner side.

[059] The control circuit is disposed on the first side of the first enlarged portion 25. Where the components of the control circuit protrude from the first enlarged portion, they are housed in slots 28 formed in the outer face of the rigid planar circular member 27.

[060] The rigid planar circular member 27 may be made from any suitable rigid electrical insulator, such as plastics or silicone. The flexible electrical insulator can be formed of the same materials as in the first embodiment.

[61] The first contact pad 9 is disposed on the First side of the first enlarged portion 25.

[62] A conductive via protrudes from the first contact pad, through the rigid planar circular member 27, to its inner side. The conductive via may be elastically compressible, for example a spring. In this way, when the cap' 27 is placed on a power cell 29 and held in the power cell slot of a device, the conductive via is slightly compressed and maintains a good electrical connection with the negative terminal of the power cell 29.

[63] The second contact pad is disposed on the first side of the narrow portion 10 26.

[64] The third contact pad is disposed on the second side of the first enlarged portion 25.

[65] The fourth contact pad is disposed on the second side of the narrow portion 26.

[066] The narrow portion 26 extends perpendicularly from the first enlarged portion 25, beyond the small annular rim and beyond the positive terminal base of a power cell in use with the cap 27, before extending substantially parallel to and in the same direction as the first enlarged portion 25. This forms a hook shape into which a power cell 28 is received in use.

[067] The cap 27 is designed not to extend beyond the circumference of a power cell 29. The small annular rim rests around the intersection between the positive and negative terminals. A power cell 29 used with the cap 27 will be made thicker by the cap 27, so a smaller-than-directed power cell 29 may be required to fit in the device's power ccll slot.

[068] Although the invention has been described in relation to solely automatic embodiments, this is not limiting. For example, a manual switch may be added or connected to the circuit of the P03 1, so that a user can manually switch the circuit on or off. This may be useful for embodiments in which the PCB is for use with a device which may be subject to motion even when not in use. In such embodiments, the automatic switching due to motion provides a failsafc in case the user forgets to switch the device off manually In other embodiments, it is preferable for there to be no manual switch, and to rely solely on the motion activated switch described above.

[069] The invention has been described above with reference to preferred embodiments, but these embodiments are not to be taken as limiting. The scope of the invention is limited by the claims.

Claims

Claims 1. A printed circuit board comprising a flexible electrical insulator having a first side and a second, opposite side; a control circuit disposed on the electrical insulator; the control circuit comprising a controller, a timer, a motion sensor, and an electronic switch having first and second terminals and a control input; the control circuit further comprising a first electrical terminal and a second electrical terminal for connecting the control circuit to a source of electrical power; the printed circuit board further comprising a first electrically conductive layer on it) the first side, and a second electrically conductive layer on the second side; the first electrically conductive layer comprising a first contact pad and a second contact pad; and the second electrically conductive layer comprising a third contact pad and a fourth contact pad; the first and second electrically conductive layers further comprising: a first electrically conducting trace between the first contact pad and the third contact pad; a second electrically conducting trace between the second contact pad and the first terminal of the electronic switch; a third electrically conducting trace between the first contact pad and the first electrical terminal of the control circuit; A fourth clectrically conducting trace between the second contact pad and the second electrical terminal of the control circuitry; and a fifth electrically conducting trace between the second terminal of the electronic 25 switch and the fourth contact pad; wherein the controller is configured to cause the electronic switch to switch to an 'on' state when the motion sensor detects movement of the printed circuit board, and is further configured to cause the electronic switch to switch to an 'off' state when the motion sensor has not detected movement of the printed circuit board for a predetermined period.
2. A printed circuit board according to claim 1, wherein the flexible electrical insulator has a first enlarged portion and a second enlarged portion, with a narrower bridge portion between the first and second enlarged portions, and wherein: the first contact pad is disposed on first side of the first enlarged portion; the second contact pad is disposed on the first side of the second enlarged portion; the third contact pad is disposed on the second side of the first enlarged portion; 10 and the fourth contact pad is disposed on the second side of both the second enlarged portion and the bridge portion.
3. A printed circuit board according to claim 2, wherein the electrical insulator is sized so as to wrap around a conventional button or coin cell, such that the first side of the first enlarged portion covers at least part of the negative terminal of the cell, and the first side of the second enlarged portion covers at least part of the planar element of the positive terminal of the cell.
4. A printed circuit board according to claim 2 or claim 3, wherein the electrical insulator is made from a synthetic polymer material.
5. A printed circuit board according to claim 4, wherein the electrical insulator is made from biaxially-oriented polyethylene terephthalate.
6. A printed circuit board according to claim 1, wherein the flexible electrical insulator has a first enlarged portion and a narrow portion extending from the first enlarged portion, and wherein: the first side of the first enlarged portion is bonded to an outer face of a rigid planar circular member which has an annular rim protruding from its inner face; the control circuit is disposed on the first side of the first enlarged portion; a plurality of slots are provided in the outer face of the rigid planar circular member to receive and accommodate the control circuit components protruding from the first side of the first enlarged portion; the first contact pad is disposed on the first side of the first enlarged portion; a conductive via protrudes from the first contact pad, through the rigid planar circular member, to its inner side; the second contact pad is disposed on the first side of the narrow portion; the third contact pad is disposed on the first side of the narrow portion; the third contact pad is disposed on the second side of the first enlarged portion; and the fourth contact pad is disposed on the second side of the narrow portion.
7. A printed circuit board according to claim 6, wherein the rigid planar circular member is sized so as to substantially cover the negative terminal of a conventional coin or button cell.
8. A printed circuit board according to claim 6 or claim 7, wherein the narrow portion extends perpendicularly from the first enlarged portion of the flexible electrical insulator, beyond the annular rim, and then extends substantially parallel to and in the same direction as the first enlarged portion.
9. A printed circuit board according to any preceding claim, wherein the 20 motion sensor is an accelerometer.
10. A printed circuit board according to any preceding claim, wherein the electronic switch comprises at least one transistor.
11. A printed circuit board according to any preceding claim, wherein the electrically conductive layers are made of conductive metal materials.
12. A printed circuit board according to any preceding claim, wherein the predetermined period is less than one minute.
13. A printed circuit board according to claim 12, wherein the predetermined period is twenty seconds.
14. A printed circuit board according to any preceding claim, wherein the controller measures the time for which it has been in continuous use, and stores 5 this in a non-volatile memory component of the controller.