The present invention pertains to a gyro-stabilized automatic pet door actuated by a magnet worn by a pet that prevents unintended openings caused by the Earth's ambient magnetic field.
Automatic pet doors actuated by a magnet worn by a pet have numerous advantages over other types of automatic pet doors. These advantages include preventing unauthorized pets from opening the pet door, allowing the authorized pets to open the pet door without having to force it open, being relatively secure against burglars, reliably weatherproof and inexpensive to provide and install.
However, automatic pet doors actuated by a magnet worn by a pet of the prior art have a disadvantage, namely, they may react to the Earth's ambient magnetic field rather than the magnet worn by a pet, causing unintended openings. Such unintended openings happen most frequently in the automatic pet doors installed in hinged entrance doors to a residence. When a pet owner opens the entrance door, the magnetic detector adapted to react to the specific rate of motion of the magnet worn by the pet moves in an ark through the Earth's magnetic field. The magnetic detector frequently cannot distinguish between the motion of the magnet worn by the pet and the motion of the door, thus causing the pet door to open. This causes annoyance to pet owners and is undesirable.
Unintended openings may also be caused by rattling of the entrance door due to a storm, earthquake and the like, or even by a pet that is not allowed to go out scratching and attacking the pet door. Another undesirable situation is when the pet owner and the pet wearing a magnet reach an entrance door together, the pet door may open at the same time as the entrance door and the pet owner may accidentally drag the pet that is half way through the pet door.
Therefore, there is a need for an automatic pet door actuated by a magnet worn by a pet that prevents unintended openings caused by the Earth's ambient magnetic field.
The present invention satisfies this need. It comprises a microelectromechanical systems gyro (also known as and referred to in this Specification as the “MEMS gyro”) disposed on the hinged door that generates a signal in response to a movement of the hinged door that overrides the signal from the magnetic detector and prevents the pet door from opening.
This invention will be better understood with the reference to
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Numeral 30 indicates a pet door. Pet door 30 is movable between a lower closed position shown in
Numeral 60 indicates a cable. Cable 60 has a first end indicated by numeral 60a and a second end indicated by numeral 60b. First end 60a is fixedly attached to primary pulley 50 and second end 60b is fixedly attached to pet door 30.
When motor 40 is energized, it spins primary pulley 50, thereby causing cable 60 to pull pet door 30 to the open position shown in
In the preferred embodiment, there is also a secondary pulley indicated by numeral 170 and a pivot pin indicated by numeral 180. Secondary pulley 170 is disposed on frame 70. Pivot pin 180 is disposed on pet door 30. Cable 60 rises at a substantially 30 degree angle from horizontal from primary pulley 50 to secondary pulley 170 and then descends at a substantially 90 degree angle from horizontal to pivot pin 180 and then leads, substantially horizontally, from pivot pin 180 to proximal end 60b.
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Numeral 110 indicates a MEMS gyro. MEMS gyro 110 is disposed on the hinged door and generates a gyro signal in response to a movement of the hinged door. The gyro signal overrides the detector signal, thus preventing lifting pet door 30 between the closed and open positions. In the preferred embodiment, MEMS gyro 110 is a motion detector, even though an accelerometer MEMS gyro can be used. A motion detector gyro is preferred due its ability to sense angular notion and not just vibrations. In the preferred embodiment, the gyro signal is generated from MEMS gyro 100 X-axis sensor. However, the Y-axis sensor or axis sensor can be used, depending on the orientation of MEMS gyro 110 on the hinged door.
Numeral 120 indicates a lockout timer. Lockout timer 120 prevents lifting pet door 30 between the closed and open positions during a lockout period following substantially immediately after pet door 30 returns to the closed position. The purpose of lockout timer 120 is to prevent pet door 30 from opening and closing for a period of time in the event the pet is loitering near pet door 30 and causing control means 100 to engage motor 40. In the preferred embodiment, the lockout period ranges from about ten seconds to about thirty seconds. It can be adjusted by the pet owner, based on the habits of the pet.
Numeral 130 indicates an open door timer. Open door timer 130 maintains motor 40 energized for a predetermined period of time substantially immediately following energizing in response to the detector signal. The purpose of open door timer 130 is to allow the pet to clear opening 70 without scarring the pet by a suddenly closing pet door 30. In the preferred embodiment, the predetermined period of time ranges from about one second to about ten seconds. It can be adjusted by the pet owner, based on the habits of the pet.
Numeral 140 indicates a first amplifier. First amplifier 140 is a three-stage low frequency amplifier. In the preferred embodiment, first amplifier 140 is tuned to the frequency of about 1 Hz. Through experiments, it has been determined that the frequency of about 1 Hz is advantageous due to the way the pet wearing transmitter 80 approaches or walks towards pet door 30.
First amplifier 140 has a first amplifier input indicated by numeral 140a and a first amplifier output indicated by numeral 140b. First amplifier output 140h is connected, through open door timer 130, to a power switch indicated by numeral 150. Power switch 150 can be placed in an “on” position and in an “off” position. When power switch 150 is in the “on” position, motor 40 is energized. In the preferred embodiment, power switch 150 is an electronic switch, such as a power Triac, turned in the “on” position by a logic “1” level and turned in the “off” position by a logic. “0”.
The detector signal applied by detector 90 to first amplifier input 140a causes first amplifier 140 to output a detector signal pulse at first amplifier output 140b. Said detector signal pulse causes power switch 150 to be placed in the “on” position during the predetermined period (which is, as discussed above, ranges from about one second to about ten seconds).
Numeral 160 indicates a second amplifier. Second amplifier 160 is also a three-stage low frequency amplifier. Second amplifier 160 has a second amplifier input indicated by numeral 160a and a second amplifier output indicated by numeral 160b. Second amplifier input 160a is connected to MEMS gyro 110. Second amplifier output 160b is connected to lockout timer 120. Lockout timer 120 is connected, through open door timer 130, to power switch 150.
The gyro signal applied to second amplifier input 160a causes second amplifier 160 to output a gyro signal pulse at second amplifier output 160b. Said gyro signal pulse causes lockout timer 120 to engage, thus placing power switch 150 in the “off” position and preventing lifting pet door 30 between the closed and open positions.
If the detector signal and the gyro signal occur simultaneously (i.e. when the pet approaches pet door 30 and the pet owner starts opening the hinged door at the same time), the gyro signal pulse occurs slightly before the detector signal pulse. This engages lockout timer 120 before open door timer 130 has the opportunity to be engaged by the detector signal pulse and keeps pet door 30 from being lifted between the closed and open positions.
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Numeral 230 indicates a pin. Pin 230 has a proximate end indicated by numeral 230a and a distal end indicated by numeral 2301. Pin 230 is disposed substantially horizontally within holes 220, such that proximate end 230a and distal end 230b project outside flanges 210.
Numeral 240 indicates a compression spring. Compression spring 240 is disposed between flanges 210 and is biasing pin 230 towards distal end 230b.
Numeral 250 indicates a tension spring. Tension spring 250 has one end attached to proximate end 230a and the other end attached to second end 60h of cable 60.
There is also a pin hole indicated by numeral 260 disposed in column 20, pin hole 260 receiving and engaging with distal end 230b when pet door 30 is lowered in the closed position, thereby preventing lifting pet door 30 by an external force.
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While the present invention has been described and defined by reference to the preferred embodiment of the invention, such reference does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled and knowledgeable in the pertinent arts. The depicted and described preferred embodiment of the invention is exemplary only, and is not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.
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