Entry Alarm

This invention relates to the field of door mounted portable alarm systems arranged to provide an audible alarm whenever a specific predetermined mechanical disturbance of the alarm is made.

There are a number of portable alarms in the prior art. In Schwartz, U.S. Pat. No. 4,484,181; an audible alarm will sound whenever the door holding the alarm is opened, which allows a spring loaded switch to close. In Ober et al. U.S. Pat. No. 4,438,428; an alarm attached to the top edge of a door has a spring loaded switch held open by the door frame when the door is closed. When the door is opened the switch can close to sound the alarm. In Okamura, U.S. Pat. No. 4,275,391; a pendulum is incorporated into the alarm such that when the alarm is moved the pendulum will close a switch to sound an alarm. In Conklin, U.S. Pat. No. 4,059,832; a portable alarm has a buzzer and batteries in series with a spring loaded plunger operated switch. The alarm is held by a special bracket over a door such that the switch plunger is held in which is the off position. When the door is opened the plunger is released and the switch closes to sound the alarm. In Gooding, U.S. Pat. No. 3,878,539; a switch comprising a coiled spring body portion extending from the housing is capable of electrically contacting a conductive member within the housing. A cap member is secured to the coiled spring arm which includes an actuating tip which extends laterally beyond a mounting surface of the housing so that when the housing is mounted relative to a door surface and the door is close an actuating tip is displaced from electrical contact but when the door is open the tip will return to a normal position and close the switch to sound the alarm. In Smith, U.S. Pat. No. 3,745,551; an alarm device which clamps onto a door and is arranged such that when the door is open an alarm will sound for 60 seconds. In Lang et al., U.S. Pat. No. 3,720,937; a battery operated alarm system completely contained within an inverted U-shaped assembly is designed to fit over the top of a door and held in place with double-sided tape. A sensor sets off a battery operated alarm unless a code-operated device on the outside of the door is correctly manipulated before the door is opened. In Patrick, U.S. Pat. No. 3,378,830; an alarm is attached to the top of a door and has an arm which extends over the top of the door. When the door is closed this arm holds an alarm circuit open when the door is opened the arm permits the circuit to close. In La Barber, U.S. Pat. No. 3,270,333; a door mounted alarm has a cooperating support bracket which assists in closing a switch in an alarm circuit when the door is opened. In Kardel, U.S. Pat. No. 3,261,010; a portable door alarm uses an adjustable bracket to fit a variety of door widths and a pair of movable members to signal relative movement between the door and structure to sound an alarm.

This invention provides alarm apparatus which is placed adjacent to a door or window to be protected. A variety of attachment means are provided to permit attaching the alarm to a flat surface using a screw, a sticky or a magnetic tape, or near the top of a door using a bracket over the door top.

A first embodiment of the alarm circuit uses a battery, an on-off switch, and a normally open trip switch in series with a buzzer. When the on-off switch is in the on position, the trip switch is arranged to close when an entry is made through a door or window to sound the buzzer alarm.

A relay coil wired in parallel with the buzzer has a normally open set of contacts wired in series with a normally closed reset switch. This series circuit of normally open relay contacts and normally closed reset switch is connected in parallel with the trip switch and the on-off switch. Even a momentary closure of the trip switch will energize the relay coil and close the relay contacts, which will keep the alarm sounding even if the trip switch opens. Since the relay contacts and reset switch bypass both the on-off switch and the trip switch, turning either or both the on-off switch and trip switch to off will not silence the alarm.

Two types of trip switches are employed. The first is a spring loaded, single pole, normally closed switch. This switch is placed within the alarm box with the switch arm extending from the top of the alarm box. The switch arm is located such that the switch is held open by the door frame when the door holding the alarm box is closed. When the door is opened the trip switch can then close to sound the alarm. Since the alarm will sound after the on-off switch is turned on until the trip switch is held open by the door frame, this trip switch arrangement is primarily intended to be used to warn a user who remains within the room that someone has opened the door.

The second type of trip switch is a rotary switch which is rotated by a line wrapped around a portion of a cylindrical shaped rotary element. The switch has a number of evenly spaced conducting segments around the periphery each of which extend from the circumference to an axle. A switch contact is made when a wiper arm adjacent to the circumference of the rotary element contacts one of the conducting segments to connect the axle to the wiper arm, with no tension on the line, the rotary element is spring loaded to return the rotary element to an initial position where the wiper arm does not make contact with a conducting segment.

This rotary switch is positioned within the alarm box with the free end of the line extending through a hole in the side of the alarm box. The alarm box is positioned adjacent to a door or window to be guarded with the line extending across the opening and attached to the opposite side. A small amount of line is pulled from the switch as the line is attached. This may close the rotary trip switch so an adjusting means is provided to change the line extending from the switch until the switch is open. This is accomplished by trial and error. With this arrangement anyone entering through the opening and either tightening or loosening the line will rotate the rotary switch and cause the wiper to contact at least one of the segments of the rotary switch and sound the alarm.

There are two arrangements used to operate the normally closed reset switch to shut off the alarm after it has been energized by the trip switch. This reset switch is necessary because otherwise the alarm would continue to sound indefinitely because of the relay contacts. The reset switch has an extension from the switch arm so a force on the arm can open the switch. A slot on the front of the alarm can accommodate either a card or a key to open the switch. Either the key or a card must match a respective mating slot in order to be inserted fully into the slot. The switch arm is positioned within the alarm such that whether a key or a card is used they must be inserted fully into their respective matching slot in order to push against the switch arm to open the reset switch. When the trip switch is opened the relay coil is deenergized, which in turn opens the relay contacts to silence the buzzer, provided the trip switch is open; or to permit turning the alarm off using the on-off switch.

A second embodiment of the alarm uses an addition to the circuits just described to provide an arm-disarm function. This circuit is housed in a separate box similar to the alarm box which is connected to the alarm box by brackets which extend over the top of a door between the two boxes. The brackets themselves are insulated from the boxes to serve as conductors between the two boxes.

This arm-disarm function uses a switch in series with a battery and a relay coil of a second relay to control a set of normally closed relay contacts. This arm-disarm switch is normally open but when closed will open the normally closed relay contacts. These relay contacts of the second relay are connected in series with the trip switch in the alarm box and when open will prevent the buzzer from sounding.

The arm-disarm switch is closed by a inserting a key or card into a matching slot in the face of this second box the same as the alarm box. This permits using a key or card to control the arm-disarm function.

In use, the arm-disarm switch is closed by inserting the key or card before the alarm is turned on to disarm the alarm. The boxes are then positioned by placing the brackets over the top of the door. The arm-disarm switch keeps the alarm from sounding even though the trip switch will be closed until the alarm is in position and the door closed. This permits turning the alarm on using the on-off switch and positioning the boxes without sounding the alarm. After the door is closed the key or card controlling the arm-disarm function is then withdrawn after the user has exited the room to arm the system while the occupant is gone.

FIG. 1A is an isometric view of the first version of the first embodiment of the alarm.

FIG. 1B is the view of FIG. 1A having a cut-out showing a portion of the interior.

FIG. 1C is a detail view of a key and its matching slot.

FIG. 1D is a side view of the first version of the first embodiment attached to the top of a door with the door closed into its frame, both being shown in cross-section, and showing the door frame forcing the trip switch open.

FIG. 1E is the view of FIG. 1D with the door ajar such that the door is moved away from its frame and the trip switch closed.

FIG. 2A is the front view of the second version of the first embodiment.

FIG. 2B is the side view of the version of FIG. 2A.

FIG. 2C is the bottom view of the version of FIG. 2A.

FIG. 2D is the back view of the version of FIG. 2A.

FIG. 3A is a front view of the second version of the first embodiment shown mounted adjacent to a sliding door.

FIG. 3B is the version of FIG. 3A shown mounted above a window.

FIG. 4A is the circuit diagram of the first embodiment, with the single pole trip switch of the first version shown in dashed lines, and the rotary trip switch of the second version shown in solid lines.

FIG. 4B is an isometric view of the rotary trip switch.

FIG. 5A is an isometric view of the second embodiment of the alarm.

FIG. 5B is a front view of the alarm box of the second embodiment.

FIG. 5C is a side view of the second embodiment.

FIG. 5D is a front view of the arm-disarm box of the second embodiment.

FIG. 5E is a side view of the second embodiment mounted over a door with the door closed into its frame, both being shown in cross-section.

FIG. 5F is the version of FIG. 5E with the door ajar.

FIG. 6 is the circuit diagram of the second embodiment of the alarm with the components of the arm-disarm box being enclosed by a dashed outline.

In FIG. 1A alarm box 10 is shown with brackets 12 sized to secure the box to the top of a door, on-off switch 14, card 16, card slot 18A in the front face of the alarm box and a number of small holes 20 to permit sound to be transmitted through the box. Key slot 19, shown in dashed outline, provides access for a key 32 as an alternative insert to card 16.

Spring loaded trip switch 22 has an arm extending through a hole 24 in the top of box 10 which is large enough to allow the arm to move to the rear of the box to a normally closed position, or move toward the front of the box to an open position. When alarm box 10 is secured near the top of a closed door by brackets 12 the door frame will force the arm of trip switch 22 to the front of alarm box 10 to the open position.

In FIG. 1D alarm 10 is shown attached to the top of a door 66 by brackets 12, with the door closed against frame 68 and switch 22 held open by the frame. In FIG. 1E door 66 is ajar from frame 68 and switch 22 is closed which will sound the alarm.

In FIG. 1B a partial view of the interior of alarm box 10 can be seen. Interior slot 18B which matches the cross-section of card 16 is mounted directly behind rectangular shaped slot 18A. If the cross-section of card 16 does not conform to slot 18B then the card cannot be inserted into the slot. Slot 18B is located within alarm box 10 behind slot 18A so that the shape of interior slot 18B cannot be observed. Card 16 has slits 26 and 27 which extend different distances into the card from the rear edge, and which are parallel to the sides of the card. Pin 28 extends across the path of slit 26 and is located such that it will be positioned at the bottom of slit 26 when card 16 is inserted full length into slot 18B. When fully inserted card 16 will push the arm of the reset switch 30 from a normally closed to an open position. Reset switch 30 is spring loaded and when card 16 is removed the spring will return the switch to the normally closed position. When card 16 is inserted into slot 18B full length a small amount will still protrude from the front of alarm box 10 to permit removing the card.

Slit 27 is not as deep as slit 26 and a second pin, not shown, is oriented the same as pin 28 in the path of this slit. The pin opposite slot 27 is closer to the rear of alarm box 10 to permit the pin to be positioned at the bottom of this shorter leftmost slit 27 as card 16 trips reset switch 30. This arrangement of slits of different depths and pins with corresponding positions, means that unless card 16 has slits at the proper location and depth the card cannot be inserted full length into slot 18B to trip reset switch 30 even if a card of the proper cross-section is used.

As shown in FIG 1C, key 32 is an alternative to card 16 and matches slot 34. Here the end of key 32 is narrower to match an offset in the bottom of slot 34 in order for the key to be inserted full length into the slot in order to trip reset switch 30.

In FIG. 2A alarm box 10 has the same circuitry as in FIGS 1A, 1B, and 1C, however the trip switch here is a rotary switch which will be described in detail later. This rotary switch is rotated by a line attached to swivel 38, ball chain 39, and connector 41 to external line 36. Connector 41 can be attached to different portions of chain 39 to change the line length and position the switch in an open position. FIGS. 2B and 2C show the relationship of swivel 3B to box 10.

In FIG. 2D a strip 11 is shown attached to the rear of alarm box 10. Strip 11, either adhesive or magnetic, or slots 40 can be used to engage the heads of screws or bolts to attached box 10 to a mounting surface.

In FIG. 3A alarm box 10 is shown mounted adjacent a sliding door with extension line 42 attached to the door by a fastener cup 44, and the line length adjusted to open switch 22 so any movement of the line trips the alarm. In FIG. 3B alarm 10 is mounted above a window 40 with extension line 42 attached to the lower window so any intrusion or window movement will trip the alarm.

In FIG. 4A the basic circuit is shown. This circuit has an on-off switch 14. A trip switch 22 which is either a rotary switch, shown in solid outline, or a spring loaded single pole switch, shown in dashed outline. A battery 46, relay 48, with normally open contacts 50 and coil 52, and buzzer 54 complete the basic circuit elements.

Note that on-off switch 14 must be in the on position in order for trip switch 22 to initially energize buzzer 54. Once buzzer 54 and relay coil 52 have been energized however then normally open relay contacts 50 will be closed which provides a path from the positive side of battery 46 to buzzer 54 regardless of the state of on-off switch 14 or trip switch 22. This ensures that when on-off switch 14 is on and trip switch 22 has closed, even if only momentarily, buzzer 54 will sound until reset switch 30 is opened.

Trip switch 22 is shown in the rotary switch version in FIG. 4B. Cylinder 56 is made of insulating material such as plastic. A number of metal conducting segments 57 are evenly spaced around the periphery of cylinder 56 and extend inwardly to axle 58 which is made of conducting material. A coil spring 59 is wrapped around axle 58 with one end attached to cylinder 56 and the other end attached to alarm box 10. A wiper arm 60 is positioned adjacent to the circumference of cylinder 56 opposite conducting segments 57 such that it will contact the conducting segments as the cylinder is rotated. Line 36 has one end attached to cylinder 56 within a groove around the circumference of the cylinder adjacent to conducting segments 57. Line 36 is arranged such that as the free end of the line is pulled cylinder 56 will rotate and coil spring 59 will wind up. When there is no tension on line 36 wiper 60 will return to an initial position between conducting segments 57.

In FIG. 5A a second embodiment 61 of the alarm is shown. This consists of an alarm box 10 which has the same circuitry and features as the first embodiment with some additions. The previous elements include brackets 12, on-off switch 14, a card 16, slots 18A and 18B, and 19, holes 20, switch 22 and hole 24. A second arm-disarm box 62 is provided which is similar physically to box 10. Box 62 also has a slot, not shown in this figure, for a card 16.

In FIG. 5B the front view of alarm box 10 is shown with these items. In FIG. 5C alarm box 10 connected to arm-disarm box 62 by bracket 12 can be seen.

In FIG. 5D the front face of arm-disarm box 62 can be seen. Here an outer rectangular shaped slot 18A and a rear slot 18B shaped to receive a card can be seen. In addition slot 19 shown in dashed outline can receive key 32. Slots 18A, 18B, and 19 can receive a card or key the same as those in alarm box 10. Here however an arm-disarm switch, not shown in this figure, is tripped in the same manner as reset switch 30 by the card 16 or key 32 whichever version is used. A light emitting diode 64 indicates the status of arm-disarm box 62 as will be explained with the circuit description.

In FIG. 5E alarm box 10 and arm-disarm box 62 are shown on opposite sides of door 66 and held in place by bracket 12 attached to both boxes and shaped to extend over the door. Here door 66 is closed against door frame 68 which bears against the arm of switch 22 holding it open. In FIG. 5F door 66 is shown partially open with switch 22 carried away from frame 68 which permits switch 22 to close.

In FIG. 6 the circuit diagram of the second embodiment is shown. This includes a number of items not used in the first embodiment. Arm-disarm switch 70 is closed by inserting either card 16 or key 32 into its respective matching slot. Relay 72, located in box 10, has a coil and normally closed contacts 76. Light emitting diode 64 is in series with resistor 78. Battery 80 can provide power for the arm-disarm functions or it can be omitted and power provided by battery 46 through wires 82 from alarm box 10. The dashed outline shows the circuit elements which are located within arm-disarm box 62. Brackets 12 are insulated and provide the connections to relay coil 74.

If battery 80 is omitted then an additional pair of wires 82 must be run from battery 46 in alarm box 10 to arm-disarm box 62 with the lines connected to each respective one of the points from battery 80 to provide the necessary power for this circuit. This alternative arrangement permits using one battery for both boxes.

The operation of the additional circuit elements of FIG. 6 provide a means of installing the alarm system over a door while turned on without the alarm sounding. In use a card 16 or key 32, is inserted into a mating slot in arm-disarm box 62 which will close switch 70 to energize the relay coil of relay 72 and open relay contacts 76. Light emitting diode 64 is also energized to show that this has occurred.

On-off switch 14 is then closed and since the system is not installed trip switch 22 is closed which would normally sound buzzer 54 but since relay contacts 76 are open this will not occur. The system is then installed over a door as shown in FIG. 5F. The user then exits the room and closes the door as shown in FIG 5E which opens trip switch 22. The user can then extract either card 16 or key 32, whichever was used, which will open arm-disarm switch 70 and permit relay contacts 76 to close and arm the system. If the door is reopened trip switch 22 will now cause buzzer 54 to sound the same as the first embodiment.

Before the user reenters the room arm-disarm switch 70 is closed by card 16 or key 32 which opens relay contacts 76 and again prevents the alarm from sounding. After the user has reentered the room on-off switch 14 can be used to turn off the system and card 16 or key 32 removed. The trip switch 22 which is used in this second embodiment is not the rotary type since a line is not used in this embodiment. The first version of the first embodiment using a spring loaded trip switch is intended primarily to be used with the alarm box mounted on a door adjacent to its top using the brackets, to cause the trip switch to close when the door is ajar.

The second version of the first embodiment using a rotary trip switch is intended primarily to be used with the alarm box mounted adjacent to a building opening with the line secured across the opening such that an intruder would either pull against or release the line to close the rotary trip switch.

The second embodiment provides a means of preventing the alarm from sounding even though the spring loaded trip switch is closed until the alarm is mounted with the brackets over the top of a door and the door closed.

Both embodiments provide either a key or card which must fit into a mating slot in order to reset the alarm after it has sounded.

This invention uses a simple holding circuit to keep the alarm sounding indefinitely until reset by a means not available to an intruder. The use of either a spring loaded trip switch or rotary switch to sound the alarm provides great flexibility in the manner of use.

While this invention has been described with reference to an illustrative embodiment, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiment, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.