Patent Application
20100313612
The present invention relates to low cost remote reminders whether a dead bolt lock of a building door is locked or unlocked.
People often leave their house and wonder whether they locked the dead bolt of their front door. Typically they would have to get out of their car and return to the house and check to see if the door is bolted. While remote status checking devices using radio communications links are known, a simple low cost device is needed.
US Patent application 2004/0080403 of Eshel relates to a lock status indicator. It comprises a remote indicator in the form of a key fob that has a visual or audio indication of the status of a vehicle lock. A time indicating device may also display the time of the last lock status change. No information on the communication sequence or operation of the indicator is provided by the inventor.
U.S. Pat. No. 6,703,919 of Baset describes a method of confirming remote keyless entry lock status using a key fob with a counter that is incremented when the lock button is pressed and reset to zero when the unlock button is activated.
U.S. Pat. No. 6,166,634 of Dean is a garage door status signaling device using a transmitter attached to a switch at the garage door. This transmitter is activated when the garage door is opened thereby sending a signal to a remote receiver (always on) with an interval timer to activate an alarm.
U.S. Pat. No. 7,196,623 of Wang is a remote reminding system to warn a user of an undesirable condition of an appliance or garage door. This is a long-range radio communications system whereby the remote unit sends signals to poll the base unit continuously. The remote unit has a computer for decrypting the encoded data and making decisions based on received information as to inform the user of certain undesirable conditions of specific appliances.
U.S. Pat. No. 7,498,936 of Maeng for a wireless event status system can be used to ascertain the status of a building door lock remotely. An informer transmitter at the door operates to transmit a status signal whenever the door lock status is changed. A receiver in a remote key fob receives the signal since it is always in the active receive state. A visual indicator in the form of a status light on the key fob is turned on or off by the received signal to indicate if the door is locked or unlocked. This last status is stored in the key fob for interrogation when the key fob is out of range of the informer transmitter.
U.S. Pat. No. 4,490,999 of Castle describes a non-electronic, mechanical door lock indicator with a rotary indicator viewable through a transparent window. The indicator is synchronized with the movement of the door bolt to indicate whether the door is locked or unlocked.
However, the prior art does not reveal a remote dead bolt status indicator which is low cost and uses a switch sensor easily installed by the customer.
It is an object of the present invention to provide a low-cost switch sensor remote dead bolt status indicator.
It is also an object of the present invention to provide a switch sensor which starts a transmitter at a door lock location upon sensing the instant that a dead bolt is locked.
It is also an object of the present invention to provide a low cost remote door lock indicator with a self shut-off feature operating after a fixed duration of time length has elapsed.
It is yet another object of the present invention to provide a switch sensor of the transmitter, whereby the switch sensor is provided at a location in the vicinity of the strike plate having an opening through which the dead bolt locks the door, so that the transmitter can communicate with the user's remote, hand held key fob indicator.
It is also an object of the present invention to improve over the disadvantages of the prior art.
In keeping with these objects and others which may become apparent, this invention is a low-cost system using a transmitter unit comprising a transmitter and a switch sensor to detect the presence of a dead bolt in a locked position, whereby the door to secured is assuredly locked/secured. The switch sensor is dual purpose. It is used to start the transmitter operation as well as to sense the bolt position in a very direct manner. The transmitter is low voltage or battery operated, such as, for example, using ordinary alkaline batteries (such as 2 or 3 AA cells). This type of power for powering the transmitter unit avoids the first cost of an AC line-powered power supply or charging stand; an ugly extension cord is also avoided in this manner. Please note, however, that an alternative embodiment includes AC/DC converter connected to power the switch sensor, transmitter and any logical circuitry for application where changing a battery would be inconvenient. A very small hand-held indicator, such as a key fob powered by a button cell, contains a receiver to communicate with the transmitter at the door.
A major feature of this invention is the ease of installation of the transmitter unit at the door with the switch sensor by a customer with average skills and minimal tools. In fact, the only tool necessary is a drill capable of drilling a single hole adjacent the dead bolt. Beyond low first cost, low cost operation in terms of long battery life is also a feature of this invention.
Since only short range communications between the transmitter and receiver in the hand-held indicator is required for this invention, advantage is taken of radio frequency bands reserved for such low power communications. In the United States, the FCC permits “unlicensed operation” (under CFR 47 part 15 regulations) of such devices in the 900 MHz, the 2.4 GHz, and the 5.8 GHz bands. Other jurisdictions have reserved bands for similar operation. Any of these bands can be used.
The low-cost features inherent to the design of this invention first relate to the communications concept and operation. At the door that is secured, the transmitter unit comprises only a simple transmitter (not a transceiver) and sensor. At the key fob, only a simple receiver (not a transceiver) is required for receiving signals transmitted from the transmitter unit. This is different than complex prior art transceivers which need transmissions in both directions or have a receiver that is always “on”, and which may be capable of performing tasks other than visual indicator status, such as locking an unlocked door from a remote position. Those features are not within the scope of the present invention.
The operation which supports the use of such a spartan system is as follows:
The switch sensor is located at the door being monitored and configured to detect an open position and a closed position of a deadbolt by which the door is secured. Upon detection of the dead bolt in the locked position, the sensor immediately starts the transmitter sending a signal in the frequency range at which the receiver in the key fob is tuned for a predetermined short time period (preferably set to be 5 minutes or less); at the end of the period, the transmitter subsystem shuts itself off regardless of the switch sensor still being activated. This self-shutoff is similar to the automatic shutoff of a digital camera after a period of non use.
If a key fob inquiry button is pressed during this transmission period and the key fob is within the range of the transmitter, the receiver within the key fob receive state is activated, the transmitted signal from the transmitter located at the door is received and a signal is generated that activates a visual or other sensory perceptible indicator, such as a green LED indicator, indicating that the dead bolt is in its locked position. Other visual or vibratory indicators may be used.
However, if the key fob inquiry button is activated shortly after the user has exited the door with the transmitter unit, and the transmitter is not transmitting the signal representative of detection of the deadbolt in its locked position but still within an operational range, the logical circuitry in the key fob decides that the deadbolt is not in its locked position. A signal is then generated to activate a visual or other sensory perceptible indicator, such as a (preferably) blinking red LED, which will glow indicating that the person has forgotten to operate the dead bolt. Any operation of the key fob out of range or after the normal transmission period will give the same blinking red LED indication even if the dead bolt is in the locked position.
Other features that are related to low cost include the switch sensor assembly. This preferably includes a few easily assembled components, such as molded plastic parts affording easy custom adjustment for most installations with a low cost switch, such as, for example, a momentary single pole, single throw SPST switch which can be a membrane switch of the type used on a telephone or calculator. Other types of switch sensors, such as magnetic, optical, ultrasonic or motion sensors and the like, can be used, as are known to those skilled in the art.
To greatly extend the life of the transmitter subassembly battery, the signal transmission is preferably pulse modulated with full power pulses of a reduced nature, such as, for example, only a 5% duty cycle or less, for example, pulses of radio frequency of 5 ms duration every 100 ms period. In this manner, full range is not sacrificed since the pulses are full power, but the battery life is extended over ten-fold compared to continuous full power transmission over the five minute transmission periods. The service life of the key fob receiver battery is very long since the receiver and indicator LED's are only operated while the inquiry button is pressed. Besides, a receiver function is a low power device compared to the transmitter function of a normal remote keyless entry automotive fob. The key fob unit is configured for easy replacement of the battery cell therein.
In an alternate embodiment, the switch sensor is provided as an integral part bonded to the conventional manufactured metal strike plate dead bolt frame that is typically attached to the door jamb. The switch sensor may be attached to the metal strike plate by two fingers extending rearward from the strike plate, or by any other mounting means which mounts the sensor to the strike plate in the vicinity of where the dead bolt moves to during the locking operation. The important feature is that the dead bolt, upon locking, is introduced through the cowling of the access hole of the strike plate in a locked position, where it activates the switch sensor concealed within an access hole for the deadbolt. The switch sensor generates a signal to activate the transmitter assembly communicating with the user's key fob, i.e., the receiver thereat. The switch sensor is preferably therefore concealed within the access hole for the dead bolt. It is a very low profile, dome operated switch, requiring only a small hole through to the interior for a small gage two-conductor cable to the transmitter assembly. This alternate embodiment simplifies the installation of the security system. Costs are minimal in view of the fact that the door jamb strike plate may be manufactured with the switch sensor by a dead bolt lock manufacturer.
The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in drawings, in which:
The following is a detailed description of example embodiments of the invention depicted in the accompanying drawings. The example embodiments are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention, as defined by the appended claims. The descriptions below are designed to make such embodiments obvious to a person of ordinary skill in the art.
A low-cost switch sensor remote dead bolt status indicator includes a switch sensor which starts a transmitter at a door lock location upon sensing of a dead bolt being in a locked position. The transmitter is provided with a self shut-off feature operating after a fixed duration of minutes length has elapsed. The indicator also includes a receiver in a hand held unit, such as a key fob capable of receiving signals from the transmitter after the user presses an inquiry key on its surface. The hand held receiver has two indicators for alternately displaying the lock's dead bolt status as being locked or unlocked. In an alternate embodiment, the switch sensor is provided as an integral part bonded to the conventional manufactured metal strike plate dead bolt frame that is typically attached to the door jamb.
Turning now to
Key fob 15 uses a low voltage power source, such as, for example, button cell 59 for power. User input is preferably achieved by momentary push button switch 18, which serves the “inquiry” function powering receiver 57 and pulse integrator 58 to energize either green LED 19 if an RF signal had been detected or alternatively flashing red LED 20 if no signal had been detected. Receiver 57 would benefit from being a single chip integrated circuit due to the reduced space within key fob 15. Other display options besides LED's are available including liquid crystal geometric or alpha types.
In the alternate embodiment shown in
In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention.
It is further known that other modifications may be made to the present invention, without departing the scope of the invention, as noted in the appended Claims.
