GB2338505A - Key for remotely operable pet door - Google Patents

Abstract

A key for unlocking a remotely unlockable pet door, includes means for detecting motion of the key and a battery operated transmitter to transmit a series of pet door unlocking signals if and only if the movement detection means detects movement of the key. Battery life is extended by avoiding signal transmission when the key is stationary either by inactivity of the pet or removal from the animal.

Description

2338505 1 KEY FOR REMOTELY-MLOCKABLE Pi9T DOOR The present invention

relates to keys f or remotely unlockable pet doors.

Pets doors are often fitted in the doors or walls of a building to allow a pet to enter or leave without the need for assistance by their owner. Pet doors which allow only specific pets through the door are known which only unlock to allow the animal to pass through if it is carrying an appropriate key. Examples as such known socalled "selective" pet doors are disclosed in EP-A-0 736 6540 GB-A-2,119,431 and GB-A-2,305,211.

A common f eature of these known pet doors is that they each include a vertically hanging door f lap mounted in a support frame and a latch mounted in the lower portion of the frame. The latch is arranged so that in the normal position it abuts one lower side of the flap and is configured to allow the flap to open in one direction away from the latch but not in the other direction. Any animal can, for example, exit a building through such a pet door but cannot enter again unless it carries the correct key.

The correct key activates the latch to retract it into the frame so allowing the flap to open in the previously barred direction to allow the animal to pass through. The latch is reset after a short time and it is constructed so that when reset the flap can depress the latch as it swings 11 - 2 back over the latch from the open position to reassume the locked position once more. Other designs of remotely unlockable pet doors may also employ such keys.

The present invention seeks to provide a key particularly suitable for a remotely unlockable pet door. Accordingly, the present invention provides a key for unlocking a remotely unlockable pet door, the key including a motion detecting means for detecting motion of the key and a battery operated transmitter means arranged to transmit a series of pet door unlocking signals if and only if the movement detection means detects movement of the key.

The key employs an active transmitter key to provide a pet door which unlocks when the key is a greater distance from the pet door than the above mentioned selective operable pet doors which use passive keys. This is particularly useful when the pet door is sized for use by larger pets, such as a dog, as the key is usually supported by a collar round the animals neck and it will be at a greater distance from the pet door when the animal's nose reaches the door than would be the case f or a smaller animal.

The key of the present invention transmits unlocking signals whenever the movement detection means detects movement of the key. When attached to a pet Is collar 3 transmission will occur whenever the pet is detected to be active and so may require the pet door to be unlocked. However, when there is no detected motion of the key, for example when the animal is inactive or the key has been removed f rom the pet's collar,, the transmission of the series of pet door unlocking signals will stop so greatly extending the life'of the battery in the key allowing the practical use of small batteries easily carried by a pet animal yet providing a useful battery life.

Such a key may have a microprocessor, for example, arranged to drive a transmitter module to transmit a digitally encoded key signal. The key may, for example. provide carrier radio frequency with a modulated digital signal being one of a number of combinations, the number being chosen so as to make it unlikely that a neighbour's pet with a similar key will have the same key combination, eight, for example.

Preferably the transmitter means continues to transmit the series of pet door unlocking signals until the expiry of a predetermined period from the last detection of movement by the movement detection means. This provides that the transmitter ceases to transmit the unlocking signals when there is a high confidence that the animal is inactive or the key has been removed and stored.

The movement detection means is preferably an 4 orientation insensitive switch, whose contacts are open at rest and closed on being moved.

Such a key preferably includes a microprocessor which remains in sleep mode until the switch closes and applies a voltage to the microprocessor to wake it up and start the transmission sequence.

An embodiment"of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a block circuit diagram for the key of the present invention; and Figure 2 is a perspective view of a key incorporating the circuit of Figure 1.

The key 1 includes a key circuit 2 which includes a 6V battery 4, a PICS08 microprocessor 6, a transmitter module 8 and a motion detection switch 10, in this particular embodiment a mercury vibration-sensitive switch.

The battery 4 is connected to a pair of power rails 12 and 14, negative and positive respectively. with a diode 16 connected to the positive battery terminal provided to provide protection should the battery be inserted with the reverse polarity. The PIC 6 is connected between the power supply rails 12 and 14 and in parallel with a 10 nF capacitor 16 for decoupling the power supply rails 12 and 14.

The motion switch 10 is corrected between the power supply rails 12 and 14 is series with a 120 kQ resistor 16 and in parallel with a 1MF capacitor 18. The resistor 16 and capacitor 18 form a pulse stretcher so in the event the usually open contacts of switch 10 close momentarily a sustained positive voltage level will be maintained at an input 20 of the PIC 6 which is connected between the resistor 16 and capacitor 18.

An output 22 of the PIC 6 is corrected in series to the negative power rail 12 via a 5nF capacitor which prevents stray RF signals from the transmitter 8 reaching the PIC 6. The output 22 is also connected to the negative power rail 12 via an adjustable resistor 24 able to provide a value in the in the region of 3 U, a 100 kú2 resistor and the transmitter 8. An antenna 27 is connected between the resistor 26 and transmitter 8.

Three resistors 28, 30 and 32 and a respective series connected code link 34, 36 and 36 are connected in parallel between a output 38 of the PIC 6 and the negative rail 12. Each resistor code link combination 28, 34:30, 36:32,38 is connected at a point between the elements to a respective input 40,42,46 of the PIC 6. The PIC 6 can determine from the signals present at inputs 42.44 and 46 when a signal is present at output 38 which of the eight possible combinations of links 34,36 and 38 is present.

6 The key circuit 2 operates as follows. If the key circuit has been motionless f or 10 seconds or so the PIC 6 will have reverted to its sleep state and will be drawing minimum current from the battery 4. On disturbance of the key circuit, due to movement of the pet to which it is attached. the motion detection switch 10 will momentarily close. The pulse stretcher circuit formed by the resistor 16 and capacitor 18 will hold the voltage input 20 of the PIC at a positive valve sufficiently long to be detected by the PIC 6 and move it to the awake state.

The PIC 6 will then output a digital signal modulated according to the desired code indicated to the PIC 6 by the code links 28 to 32 and as determined by the combination of intact links 34,36 and 38. The transmitter 8 generates a carrier signal for transmission via the antenna 27 whenever it receives power via the output 22 of the PIC 6 and so it will transmit a modulated signal corresponding to the modulated output from the PIC 6.

The PIC 6 is. in this embodiment, arranged to transmit ten such digitally encoded key signals at one second intervals after a positive level is detected at input 20. If the motion switch 10 detects motion during this ten second transmission period the count resets. That is the series of transmissions will continue until about ten seconds after the last detected motion of the key circuit.

7 Af ter ten seconds of no detected motion the PIC 6 will return to its quiescent sleep state and transmissions of the digitally coded signals will cease so reducing batter power consumption.

When movement is again detected, the microprocessor will wake up a further series of unlocking signals will be transmitted under the control of the microprocessor until, once more, lack of detected movement by the switch results In the microprocessor stopping signal transmission.

The type of unlocking signal and the repetition rate can be chosen as required by simple trial and error but could, for example, be a digitally modulated radio signal transmitted via for reception by a receiver in a pet door when close enough to it, for example 1 to 2 metres, and so at a suf f icient distance to be detected well bef ore the pet's muzzle touches the flap.

Referring now to Figure 2, the key 2 contains within the circuit 2 of Figure 1, the battery 4 being removably insertable into a battery compartment (not shown) beneath a removable battery cover 40. A split ring 42 is fixed to the top of the key 1 to allow it to be removable attaco d to the collar 44 of a pet.

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Claims (8)

1. A key f or unlocking a remotely unlockable pet door, the key including a motion detecting means for detecting motion of the key and a battery operated transmitter means the key being arranged to transmit a series of pet door unlocking signals if and only if the movement detectionmeans detects movement of the key.

2. A key as claimed in claim 1, in which the motion detector means includes a vibration or motion sensitive switch.

3. A key as claimed in claim 1 or 2, in which the transmitter means continues to transmit the series of pet door unlocking signals until the expiry of a predetermined period from the last detection of movement by the movement detection means.

4. A key as claimed in claim 3 including a microprocessor which on detection of movement of the key by the movement detection means adopts a waking state in which it controls the transmitter means to transmit the series of pet door unlocking signals and after the predetermined period reverts to a sleep state.

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5. A key as claimed in claim 4 in which the microprocessor in its wake state is arranged to determine which combination of a set of openable links are open, the determined combination determining the door unlocking signals that are transmitted.

6. A key as claimed in any preceding claim in which each signal of the series of signals is a digitally coded signal.

7. A key as claimed in any preceding claim including means for removably attaching the key to a pet collar.

8. A key for unlocking a remotely unlockable pet door. substantially as herein described with reference to the accompanying drawings.