Automatic power control module for battery powered devices

A power control module which can be used to automatically open a power circuit for electrically operated devices, particularly battery operated devices, during predetermined periods of non-use. A timer is reset by a motion detector indicating continuing use. The timer controls a transistor switch which closes and opens the power circuit as required. The timing interval can be user-selected e.g., by programming a microprocessor controller. The transition time between conductive and non-conductive states of the transistor can also be controlled to prolong the life of incandescent bulbs or other sensitive load devices.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to a control module for battery operated devices, which functions to open the battery circuit after a predetermined period of non-use. A timer including a motion detector is provided to re-close the battery circuit and reset the timer. The device is self-contained and is configurable so that it can easily be accommodated in many existing products without the need for redesign, or with only minimal redesign. The invention can have utility in flashlights, toys, and numerous other battery-operated devices for which power is needed only when the device is actually in use.

2. Relevant Art

A known problem with battery-powered devices, such as flashlights, toys, etc. is that they are often inadvertently left on after use, resulting in the cost and inconvenience of premature replacement of batteries. To avoid this, some battery-powered devices, include timers as part of the circuitry which shut the devices down, or initiate a standby mode after a predetermined period of non-use. Several such devices are mentioned in my above-referenced patent. There do not, however, appear to be commercially available shut-off devices adaptable to a wide range of products which can simply be purchased off the shelf, and interfaced with an existing product or design. Availability of such devices could reduce design time and cost, and through standardization, reduce component and even assembly cost. A properly designed device of this kind could be incorporated in many existing devices even by the end user, or during manufacture with no redesign in many instances, or with only minimum packaging and/or component layout redesign. A need for such a device clearly exists.

Another known problem, particularly in devices such as flashlights, is the need for frequent replacement of bulbs. Incandescent lamps for flashlights are rarely designed for long-life, and indeed, the opposite is usually true. Light output is generally increased at the expense of bulb life. Seemingly, spare bulbs are never at hand when needed, and replacement is often inconvenient in any event. A practical way to increase bulb life without reducing light output which could readily be incorporated in a flashlight would be desirable, but that, too, does not appear to be commercially available.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to satisfy the above-described needs for a self-contained unit which provides an inactivity shut-off function and optionally, bulb-life enhancement, and which can be inserted in existing products with little or no redesign.

An additional object of the invention is to provide a control module which can be used with a variety of existing electrical and electronic devices to enhance utility through availability of programmable functions.

A further object of the invention is to provide a self-contained power control module for battery operated devices which can be programed for use in a variety of applications with different operating parameters.

A power control module device according to one feature of the invention comprises an electronic circuit board including a timer, a timer reset circuit, a transistor switch and an associated control circuit, and a motion detector, like an accelerometer. These are all mounted on a circuit board which can fit into many existing devices. The transistor is operable to open the battery circuit, thereby turning off a connected load after a predetermined period of non-use such as two minutes, if the device remains motionless.

The battery circuit is reactivated if motion of the device triggers the motion detector to reset the timer which then remains on for another two minute interval. The timer can also be reset by turning a main switch off and back on again. If the device is in constant motion, the motion detector is repeatedly reset for successive two minute intervals and the device remains in operation.

According to a second feature of the invention, the module is in the form of a thin disc or plate. Different sizes can be provided for use with different type batteries and battery compartment configurations. The module can then be installed in the battery compartment, in line with, or adjacent to the batteries, with the transistor switch in series with the battery circuit.

According to a further feature of the invention, the switch control circuit can include a delay timer which provides for controlled turn on and turn off of the transistor switch to enhance the life of a load device such as an incandescent lamp in a flashlight.

According to yet a further feature of the invention, an integrated circuit programmable controller can be included to provide selectable inactivity time out intervals, and selective operation of the turn on-turn off delay, and other user-programmable functions.

According to another feature of the invention, the module can be used with remotely located motion sensors and also to control mains-powered loads to provide programmable capabilities in devices lacking such features when purchased.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1A and 1Bshow schematically a first embodiment of an automatic shut-off control module, generally denoted at1. This is configured for use with a standard nine volt battery. Shut-off device1includes a base plate9which is preferably a printed circuit board (PCB) fabricated in conventional fashion. On one side9A of PCB9are mounted a transistor switch4, a control unit5including a timer, a timer reset circuit, and a driver for transistor4, a motion sensor6, a female snap connector2and a male snap connector3. Connectors2and3are configured for respective attachment to the male (positive) and female (negative) terminals of a nine volt battery (not shown).

Mounted on the other side9B of PCB9are snap terminals2A and3A, respectively aligned with terminals2and3. Terminal2A is male to correspond to the male positive terminal of the battery, and terminal3A is female to correspond to the female negative terminal of the battery. Terminals3and3A are electrically connected by a conductive sleeve3B to provide a direct connection through the circuit board to the negative terminal of the battery. Terminals2A and3A are intended for connection in conventional fashion to provide operating power for a load device through a main on-off switch (both of which are not shown in the interest of simplicity).

As described in more detail below in connection withFIG. 6, transistor4provides a switched connection between positive terminals2and2A, which are accordingly connected to the emitter and collector terminals if a junction transistor is employed, or to the source and drain terminals when a MOSFET or the like is employed.

Thus, when the main switch is turned on, transistor4is switched to its conductive state, and the battery circuit through contacts2and2A is closed, permitting the load device to operate. As long as the timer in control circuit5is repeatedly reset by motion sensor6within its timing interval, transistor4remains conductive, and the battery circuit remains energized. However, if the timer times out, transistor4is switched to its non-conductive state and the battery circuit is opened. Transistor4remains non-conducting, and the battery circuit remains open, until motion is again detected, or the main switch for the load device is turned off, then on again.

Alternatively, positive terminals2and2A can be connected-through on the circuit board with the transistor providing a switchable path between negative terminals3and3A, depending on the type of transistor used and the design of the electronic circuit.

An outer skirt7formed of any suitable resilient material, may be insert molded onto circuit board9to give it orientation for connection to the battery terminals and help hold it in place along with its snap connectors2and3.

Control circuit5can be fabricated as an integrated circuit on a custom circuit silicon die (a small chip of silicon with custom circuitry such as a computer chip) for high volume, low cost production. The chip is preferably surface mounted as shown on PCB9and then encapsulated with epoxy or the like onto board9for moisture and mechanical protection. Depending on the heat dissipation requirements, transistor4may be part of chip5, or may be separately mounted and encapsulated, as shown.

Motion detector6for the control module1inFIG. 1is comprised of a small metal ball6A movably enclosed under an arcuate metal conductive cover6C and is positioned and configured to make interrupted contact with an arcuate circuit trace6B on PCB9as movement of device1causes motion of the ball. This intermittent contact closure continuously resets the timer in control circuit5as described below in connection withFIG. 6.

FIGS. 2A and 2Billustrate a second embodiment of the automatic time-out shut-off device, generally denoted at10. This is configured to be placed between two series-connected batteries31and32mounted in a battery compartment30such as the barrel of a flashlight or the like, as shown inFIG. 3. For simplicity, the load device and the main on-off switch are not illustrated.

Control module10includes a switching transistor14, a control circuit15, and a motion sensor16, all of which may be respectively the same as or similar to transistor4, control circuit5, and motion sensor6previously described in connection with the embodiment ofFIGS. 1A and 1B. All of these components are mounted on a PCB19with the transistor and control circuit encapsulated, also as described above.

As will be appreciated, PCB19is sized and configured to fit into battery compartment30with the overall thickness of device10being accommodated by compression of spring34at one end of battery compartment30.

The outside edge of PCB19can be encapsulated with a resilient strip17made of rubber or the like, with a flexible tab18for aiding in removing the batteries from the battery compartment30as shown inFIG. 3.

When device10is installed, terminals12and12A are respectively in contact with terminals35and36of batteries31and32. Terminals12and12A are insulated from each other by circuit board19, and thus provide a break in the battery circuit for the load. Closure of the battery circuit is effected by connection of terminals12and12A in series with the current path of transistor14, e.g., with the collector and emitter terminals in the case of a junction transistor, or with the source and drain terminals of a MOSFET or the like, as in the embodiment ofFIGS. 1A and 1B.

Also as in the embodiment ofFIGS. 1A and 1B, when the main switch for the load device is turned on, transistor14is switched to its conductive state, and the battery circuit is completed. As long as the timer in control circuit15is repeatedly reset by motion sensor16within its timing interval, transistor14remains conductive, and the battery circuit remains energized. However, if the timer times out, transistor14is switched to its non-conductive state and the battery circuit is opened. Transistor14remains non-conducting, and the battery circuit remains open, until motion is again detected, or the main switch for the load device is turned off, then on again.

FIGS. 4A and 4Billustrate a power control module, generally denoted at40, which is similar to device10ofFIGS. 2A and 2B, but also includes a spring clip connector50preferably formed of an electrically conductive material, and having first and second circular end plates51and52, and a connecting arm41. Control module40is attached to end plate52in any suitable manner, as discussed more fully below. Spring clip connector50is configured to snap onto a cylindrical battery54installed with one or more additional batteries54A in a battery compartment55, as illustrated inFIG. 5. When spring clip50is attached to battery54, a contact area41A on end plate51is connected to the negative battery pole56, and a contact42on module40is connected to positive battery pole60.

Control module40includes a switching transistor44, a control chip45including a timer and timer reset circuit, and a motion detector46, all mounted as previously described on a PCB49. A second terminal42A on the side of PCB49opposite to terminal42permits connection of the batteries and the control module in the battery circuit for the load device (not shown). For this purpose, end plate52includes a circular central aperture61through which terminal42A is accessible. As will be appreciated, module40is secured to the margin of aperture62. This may be done by a suitable adhesive, or in the process of encapsulating transistor44and control chip45.

Transistor44and control chip45function in the same way as transistor24and control chip25in the embodiment ofFIGS. 2A and 2Bto connect terminals42and42A when the battery circuit is intended to be energized, and to break the connection between terminals42and42A when the battery circuit is intended to be de-energized.

With the construction ofFIGS. 4A and 4B, electrical connections to both poles58and60of battery54are available at module40. This permits operation of the control device with a minimum series circuit voltage drop.

FIG. 6shows a basic block diagram schematic of the electrical control circuitry of the automatic time-out device with its flow-charted operational characteristics shown inFIG. 7.

InFIG. 6, a generalized module70is shown connected between battery input terminals62and62A in a series circuit comprised of a battery72, a load74and a main on-off switch76. Connection between terminals62and62A is through the current path of a transistor switch65.

Control module70is also comprised of a control circuit65A which drives transistor65into and out of conduction as required, a timer circuit64and a timer reset circuit64A, and a motion detector66. Control circuit65A and timer64respond to an off-on transition of switch76to start the timing interval and to place transistor65in the fully conductive state. This completes the battery circuit through terminals62and62A, and energizes load74. Timer reset circuit64A, and motion detector66cooperate to reset timer64whenever motion is detected.

If the timing interval ends without motion being detected, timer circuit operates control circuit65A to place transistor65in its non-conductive state. This opens the battery circuit and energizes load74. A long as switch76remains closed, motion sensed by detector66will reset timer64and transistor65will again be placed in its conductive state to re-energize the battery circuit. A similar result is obtained if main switch76is opened and re-closed.

No exact electrical circuit implementation for module70is disclosed, as many circuits capable of performing the functions described will be readily apparent to those skilled in the art.

In this connection, it should be recognized that the required functions may readily be provided by a programmed microprocessor implementation. That has the advantage of facilitating programmed setting of a desired time out interval, and also selectable provision of controlled turn on and turn off of transistor65.

It should also be recognized that the life of certain devices such an incandescent bulbs or sensitive electronic devices can be significantly increased if they are not subjected to the shock of large current changes when they are energized and de-energized. This can be achieved according to the present invention by incorporating into transistor control circuit65A a delay feature providing a staged transition, e.g., over a one or two second interval, between the conductive and non-conductive states of transistor65. Various ways of doing this, both in a circuit implementation of control circuit65, or as part of a microprocessor implementation, will be readily apparent to those skilled in the art.

The resulting soft turn on and turn off current to the incandescent filament, etc., can greatly enhance the life of such a device. Additionally, either or both the automatic turn off and the controlled transition functions can be made selectable, especially by preprogramming in a microprocessor implementation, while use of switches or the like to provide this function (or time-out interval selection) might prohibitively increase the size of the module.

The programmable microprocessor implementation with a suitable interface such as a PC or dedicated input device can also allow use of the control module for programming customized on/off control of a variety of existing battery operated devices, or even mains-operated devices. For the latter purpose, module could be incorporated in a unit having a plug for direct connection to the wiring, and a receptacle for providing power to the controlled device. Thus, on/off control desired for particular time of day, for example, for home lighting, heating or an oven could be provided. Additionally with suitable motion detectors (including, if desired, remote detectors), the device can readily be used as an intrusion detector for homes to provide an alarm and turn on lights as desired. Other applications will also be readily apparent to those skilled in the art.

The motion detector can be a number of different types known in the art such as accelerometers, mechanical vibration sensors vibrating wires, etc., as well as various non-contact sensors for detecting motion in volumes of space such as rooms. For example, a drop of mercury could replace the ball to make and break contact with the traces on the circuit board.

Therefore, while the present invention has been described a relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is therefore intended that the present invention not be limited by the specific disclosures herein but that it be afforded the full scope defined by the appended claims.