Cleaning compositions

This invention relates to a movement sensor, and particularly, but not exclusively, to a movement sensor suitable for installation in a valuables box.

Most commonly known jewellery boxes and cash boxes are lockable but are small enough to be easily portable and can therefore be carried away, for example by a house burglar who can then empty the contents at leisure. It has therefore been proposed to provide a box having a movement sensor operable to actuate an alarm when the box is moved. This has the advantage that a potential thief can neither attempt to open the box nor carry the box away without setting off the alarm and hence being discovered.

However, the provision of a suitable movement sensor for such a box has proved difficult. The sensor should be inexpensive, reliable and sensitive. It should not be easily damaged by, for example, dropping the box. It would also be desirable for the sensor to be capable of operating correctly irrespective, to a large extent, of the precise orientation of the sensor. This latter feature is desirable to allow for situations in which the box is not located on a precisely horizontal surface, and conflicts to a certain extent with the requirement for good sensitivity. It is also desirable that the operation of the sensor should not rely on the movement taking place in a specific direction, in which case operation of the sensor could be avoided by careful handling.

U.S. Patents Nos. 3,742,478 and 4,196,429 describe a number of motion sensors in which an electrically conductive ball is confined for movement within a generally cylindrical container. On an inner surface of the container (either on the cylindrical side wall or on one or both of the end walls), two sets of elongate contacts are formed, the contacts of each set being interdigitated with those of the other set. The ball is able to bridge an adjacent pair of contacts so as to form an electrical connection between the two sets. As the device is moved, the ball rolls over the contacts, thus successively making and breaking connections between the two sets. This is detected by a circuit coupled to the contacts, and an alarm is then sounded.

A problem with these arrangements is that the alarm may sound in response to a slight vibration, resulting in the ball successively making and breaking the same contact, without there being any bodily movement of the device. To avoid this, one of the arrangements described in U.S. 3,742,478 has a third set of contacts which are interdigitated with the first and second sets. The alarm is sounded only after the ball first makes contact between the first and second sets of contacts, and subsequently makes contact between the second and third sets. This requires a complicated arrangement of electrodes and also means that the sensitivity of the device is dependent upon the initial position of the ball prior to movement of the device.

A further, significant disadvantage of the arrangements of U.S. 3,742,478 and U.S. 4,196,429 is that they rely upon the ball bridging adjacent contacts which thus have to stand proud of the surface over which the ball rolls. The movement of the ball is therefore, unavoidably, impeded and consequently the sensitivity of the device is substantially reduced. In addition, the elevated contacts produce a tendency for the ball to run along between contacts rather than ride over the upper surfaces thereof, which would prevent the alarm from sounding. It is proposed in each of the patents to arrange the contacts such that this tendency is reduced; however, this does not entirely solve the problem and results in a complicated electrode pattern.

EP-A-0098913, falling within Article 54(3), discloses various movement sensors. In the embodiments of Figures 21 to 24, a conductive ball can roll over contacts spaced in succession along a curved path, thus successively connecting them to conductive guides which define the curved path followed by the ball as it moves. Complicated track arrangements are required to achieve variable sensitivity.

It would be desirable to provide a sensor which is more sensitive, more compact and more easily manufactured.

According to the invention there is provided a movement sensor comprising: <ul id="ul0001" list-style="none"><li>an electrically conductive ball;</li><li>a substantially cylindrical structure for confining the movement of said ball, said structure comprising a side wall and an end wall;</li><li>first and second sets of electrical contacts carried by said side wall, said contacts being spaced around the inner circumference of said structure with the contacts of said first set interdigitated with the contacts of said second set;</li><li>terminal means at said end wall, said ball being capable, during movement within said structure, of successively, electrically connecting the contacts of said first and second sets with said terminal means; and</li><li>a signal generating circuit coupled to said contacts and said terminal means and operable to detect said successive connections, and to provide a movement signal if said successive connections are detected, whereby an alarm can be generated in dependence on whether or not the movement signal is provided.</li></ul>

In the preferred embodiment, a first detection signal is provided when the movable part or ball is in one position, and a second signal when the part is in a different position. The movement signal is generated when the first and second signals have both been provided. Preferably, the movement signal is produced only if both detection signals have been provided within a predetermined interval, and preferably irrespective of which of these signals occurred first so that the movement signal is given whichever direction the part has moved in.

The embodiment of the invention described below is arranged so as to detect when the part is in any of a plurality of "first" positions, and any of a plurality of "second" positions which are intermediate the first positions. After the sensor is moved from its position of rest, the continued movement of the part will cause it to pass through either a first position followed by a second position, or a second position followed by first position and the movement signal is then generated.

It will be appreciated that, in contrast to the arrangements of U.S. 3,742,478 and 4,196,429, by making the sensor respond to movement of the part between two separate positions, irrespective of the direction of movement, the sensor can be constructed so that it operates reliably irrespective of the initial position of the part, or of the sensor as a whole. This means that the sensor does not need to be positioned accurately for it to operate correctly and also means that it is less subject to damage because it does not rely upon the precise alignment or positional relationship between two relatively movable components. The arrangement also has the advantage that precise adjustment of the sensor at the manufacturing stage is unnecessary.

By arranging for the movement signal to be produced only if both detection signals have been provided within a predetermined interval, it is possible to avoid erroneous operation of the alarm due to a very slow, drifting movement of the movable part following the arming of the sensor. This is very important when the sensor is so designed that the part can move very easily and consequently good sensitivity is achieved. In these circumstances, after the sensor itself is left at rest, there is a strong likelihood of the part continuing to move for an extended period. Such an arrangement also provides a means of controlling the sensitivity of the sensor.

As indicated above, the movement sensor of the invention is of particular value when used in a valuables box, and the invention extends to a valuables box including such a movement sensor. However the invention also has value in other fields. In addition, the movement sensor could be sold as a unit having means for attachment to items of value, to prevent theft of the items.

An arrangement embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: <ul id="ul0002" list-style="none"><li>Fig. 1 is a schematic circuit diagram of a movement sensor according to the invention;</li><li>Fig. 2 shows a delay circuit which can be used in the circuit of Fig. 1; and</li><li>Fig. 3 is a perspective view showing the structure of the movement sensor.</li></ul>

The circuit of the movement sensor is shown in Fig. 1. The sensor has a movable part 4 normally connected to a grounded terminal. The part 4 can electrically connect the terminal (as will be explained) to contacts 16 and 18 which are connected to inputs of respective delay circuits 22 and 24, the outputs of which are connected to respective inputs of an OR gate 26.

The inputs and outputs of the delay circuits 22 and 24 and of the OR gate 26 are normally at a highvoltage level. The delay circuits 22 and 24 are each arranged so that, as soon as its input goes low, its output also goes low. However, when the input goes high, there is a predetermined delay before the output goes high.

A suitable delay circuit is shown in Fig. 2. This comprises an OR gate 28 having both its inputs normally held high by a resistor 30. A capacitor 32 is connected between its output and its inputs.

If the inputs are shorted to ground, the output voltage immediately goes low. If the short is then removed, the input voltage will rise gradually as the capacitor 32 is charged via the resistor 30, so that there will be a delay before the output goes high.

Referring again to Fig. 1, it will be appreciated that the output of one of the delay circuits 22 and 24 will go low as soon as the part 4 touches the appropriate one of the contacts 16 and 18. If the part 4 then leaves that contact and touches the other contact within the predetermined delay time, both the outputs of the delay circuits 22 and 24 will be low simultaneously, so that the output of the OR gate 26 will go low. As will be explained, this will cause generation of a movement signal.

The delay of the circuits 22 and 24 is selected to be short enough so that the sensor is not erroneously activated because of very slow, drifting movement of the part 4, for example after the sensor has been positioned and switched on, and long enough so that the sensor is not too insensitive. A suitable delay time is about half a second.

The output of the OR gate 26 is delivered to the input of a further delay circuit 36, the output of which constitutes the movement signal. This is used to generate an audible alarm and is referred to below as an alarm signal. The delay circuit 36 is used to ensure that the alarm signal is generated at least for a predetermined minimum duration, e.g. of about twenty seconds.

The output of the delay circuit 36 is delivered via a contact of a switch 38 to an alarm generator 40. The alarm generator 40 is a standard integrated circuit available from Motorola under the part number 14466, for use in smoke-detector alarms. The output of the generator 40 drives, via a resistor 42 and transistor 44, and audio transducer 46 to generate a loud alarm sound.

The alarm generator 40 and audible transducer 46 receive power via a supply line 48 coupled directly to a battery 50. These parts of the circuit are permanently energised. The current drain is normally very small, and in fact tends to extend the life of the battery. In addition, this arrangement permits the circuit 40 regularly to check the battery level, and if it is found to have dropped significantly, the transducer 46 is caused to emit a distinctive sound so as to warn the user.

With the switch 38 positioned as shown in Fig. 1, the remaining parts of the circuitry receive power via a supply line 52. These parts of the circuitry can be switched off by turning the switch 38 to the centre contacts. In addition, the apparatus can be put in a test mode by turning the switch 38 to the lowermost contacts, which causes the input to the audible generator 40 to be grounded and thus produces an alarm.

Fig. 3 shows the structure of a movement sensor according to one embodiment of the present invention. The movement sensor 200 of this embodiment comprises a cylindrical container formed of a circular cross-section side wall 102 and two end walls 104 only one of which is shown in Fig. 3 for the purposes of clarity. The closed container houses a ball 106 made of conductive material, and in this case formed by a metal ball-bearing. The ball 106 has a diameter slightly less than the height of the container.

The inner surfaces of the end walls 104 are electrically conductive and electrically connected together. The side wall 102 has on its inner surface electrically conductive regions 108 and 110. The region 108 has the shape of a ring with a plurality of contact arms 112 extending therefrom. The region 110 is shaped as another having a plurality of contact arms 114 extending therefrom and interdigitated with the arms 112. The interdigitated contact arms 112 and 114 extend in the direction of the height of the cylindrical container. The regions 108 and 110 can be formed by any of the known methods for forming printed circuit boards, e.g. etching, or preferably by using printed conductive ink. It is important that the regions do not impede movement of the ball 106, and for this reason they are preferably substantially flush with the inner surface of the side wall 102.

Referring again to the circuit of Fig. 1 the ball 106 corresponds to the movable part 4, and the contact arms 112 and 114 to the contacts 16 and 18. The movable part, or ball 106, is connected to the ground terminal via its contact with an end wall 104.

In almost any orientation of the sensor 200, the ball 106 will rest with one part of its surface contacting an end wall 104, and another part touching either one of the arms 112, 114, or the space between a pair of such arms. Even if the ball 106 is not already in such a position, slight movement of the sensor 200 will cause it to adopt such a position. If desired, one or both end walls 104 and/or the side wall 102 can extend inwardly in its mid-region to encourage or guarantee the adoption of this position. Indeed, by inwardly doming the end walls 104 it is possible to arrange for the ball to be confined so that it can only run around the inner rim of the cylinder. Thereafter, movement of the sensor 200 will cause the ball to roll, while maintaining contact with the side wall 102, so that the ball 106 successively touches respective arms 112 and 114, thus setting off the alarm.

The sensor 200 operates in any plane. Whatever orientation the sensor 200 is in to begin with, the neutral equilibrium of the ball 106 and its tendency to roll within the container while maintaining two points of contact will ensure that the ball 106 electrically connects an end wall 104 with, successively, contact arms 112 and 114 formed on the side wall 102. If, for example, the sensor is moved while the end walls 104 are horizontal, the ball will tend to roll around the rim; if, as another example, the sensor is moved while the end walls 104 are vertical, the ball will tend to rock on the lowermost part of the inner surface of side wall 102.

The arrangement of Fig. 3 has the advantage that, for a given minimum spacing between arms 112 and 114, a large number of these arms can be provided because they are located on the side wall 102 around the outer circumference of the sensor.

It is possible to form the conductive regions 108 and 110 on a substrate which is then attached to an inner surface of the cylindrical container.

The sensor described above can be installed in a valuables box (not shown), so that the sensor can be armed using the switch 38, the valuables box closed and locked, and thereafter any movement of the box will cause the alarm to sound. If desired, there could be a delay between the operation of the switch 38 and the arming of the sensor to allow the user time to put the box away before the alarm goes off. There could if desired also be a delay between the sensing of movement and the activation of the alarm, so that when the owner wishes to open the box he will have time to switch off the alarm before the sound is generated,

The circuit is arranged so that once the alarm starts, the sound will continue for a predetermined period, e.g. twenty seconds, after the last detected movement of the box. Alternatively, the detection of movement could initiate the generation of sound for a predetermined delay period, and the circuit be arranged to continue to generate the alarm at the end of that period only if movement is detected at that time.

The circuit may incorporate a switch which is actuated by the opening and closing of a lid of the box so that the alarm is activated by the closing of the lid.