Universally Adjustable And Focusable Alarm Apparatus And Electric Circuitry Therefor

Abstract

Apparatus having a base attachable to a surface. A hollow holder is universally supported by the base and an electric element of a light beam transmitting and receiving circuit is mounted in the holder. The light beam travels through an outer end opening of the holder and fitted to the holder to extend across the outer end opening are a light focusing lens and a light filter. A rheostat is provided in the circuit to adjust the intensity of the light beam. The apparatus has an alarm circuit which is energized when the light beam is broken by an object of a predetermined size and the alarm circuit includes an audible and a visual signalling device as well as a two-way switch for selectively and alternatively controlling the two devices.

Description

BACKGROUND OF THE INVENTION

This invention relates to burgular and fire alarm apparatus of the type which utilizes a beam of light to guard selected areas of a room or the like.

Conventional alarm systems using an electric eye as a triggering element are often bulky and expensive with the result that generally they are limited to use in specific locations in offices and warehouses etc. of the more well to do business establishments. The cost factor has been known to rule out attempts to adapt such systems for use in small businesses and in private homes since the equipment now on the market is quite complex and remains costly even though simplified and reduced in size. In addition, such alarm sounding equipment must be given certain safeguards to avoid false alarms and this tends to make them less reliable. Another reason for loss of effectiveness in alarm systems not specifically designed for a particular installation, is that the light beams cannot be precisely controlled with the result that a small object such as a flying insect or the like can interupt the overly sensitive beam. This causes frequent false alarms which always annoy and sometimes frighten a householder and this, of course, is entirely unsatisfactory.

SUMMARY OF THE INVENTION

The above as well as other disadvantages of conventional alarm systems are overcome by the present apparatus which is small, compact and precision built. Means is provided for mounting the light beam transmitting and receiving elements so that these elements can be located near the remainder of the unit as is desirable. Mirrors strategically located about the guarded area reflect the beam along selected paths between the transmitting and receiving elements. It then becomes possible, in some installations at least, to hide the entire unit from view. The two key elements of the apparatus are contained within housings which permit the light beam to be projected in a variety of directions as might be required for different room layouts and the beam can be focused by means of a reflector and a lens so that there is no unnecessary defusion of the light rays. Filters are provided to render both the light beam, and the photocell receiving the light beam, invisible so that an intruder is not forewarned of the presence of the alarm and therefore is not able to avoid triggering the system.

These as well as other features and advantages of the present alarm apparatus will be described in detail in the following specification and shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the alarm apparatus in accordance with the present invention,

FIG. 2 is an enlarged section taken on the line 2--2 of FIG. 1,

FIG. 3 is a plan view of the transmitter housing, and

FIG. 4 is a side elevation, with parts broken away and shown in section, of the receiver housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, there is illustrated a typical installation for the present alarm apparatus, which apparatus is indicated generally by the numeral 10. In this particular installation, the apparatus 10 is shown installed in a room 11 having walls 14, 15, 16 and 17. Walls 15 and 16 may have windows 19 and 20 while wall 17 may have a door opening 21. The apparatus includes a control unit 24 which conveniently is fastened to the wall 14, this control unit being provided with a number of electrical and electronic circuits one of which is a light beam transmitting and receiving circuit generally indicated at 25. Circuit 25 includes a main control switch 27, a rheostat 28, a transmitter 30 and a receiver 31 as well as numerous other elements which have not been shown. The transmitter 30 and receiver 31 of the apparatus are also fastened to wall 14 preferably adjacent walls 15 and 17. This particular installation requires the use of mirrors 33 and 34 which are mounted at opposite corners of the room. A light beam, as indicated by chain dotted line 36 in FIG. 1, is generated by the apparatus and is projected by the transmitter 30 to the mirror 33, thence to mirror 34 and from the latter mirror back to the receiver 31. Apparatus 10 also includes an alarm circuit generally indicated at 40, FIG. 1. This alarm circuit is provided with appropriate elements including a bell 42, a light bulb 43 and a two-way switch 44. The arrangement is such that whenever the light beam 36 is interrupted, as it would be by an intruder entering the room 11, the circuit 40 is energized and the bell 42 sounds an alarm to warn others of the break-in.

Referring now to FIG. 2, the transmitter generally indicated at 30 is shown to comprise a housing 50 which is provided with a socket-like base 51. Base 51 has a peripheral wall 52 and the outer edge 53 of this wall curves inwardly. A flange 55 is formed on the inner edge of the peripheral wall 52 and preferably this flange is fitted with a disc 56 which serves as a closure for the inner end of the base. As shown in FIG. 3, openings 58 are provided in the flange 55 and the disc 56 to receive screws 59 which are used to secure the transmitter housing 50 to the wall 14.

Base 51 supports a hollow holder 62 which is a ball-like member having a substantially spherical sidewall 63 partially enclosed by the peripheral wall 52 of the base. Between the holder wall 63 and the base wall 52, a resilient bearing ring 65 is mounted, the bearing ring being tapered in cross section to conform to the adjoining walls of the base 51 and holder 62. A clamping band 67 serves to hold the bearing ring 65 in position, and this clamping band has a flange 68 which slidably engages the peripheral wall 52 of the base. Circumferentially spaced screws 70 are fitted to the flange 68, these screws extending through slots 71 (FIG. 2 only) formed in the peripheral wall 52 near the flange 55. This arrangement enables the clamping band 67 to be moved towards or away from the closure disc 56 as required so as to apply a suitable amount of compression to the bearing ring 65 and hold said ring in firm engagement with the sidewall 63. Thus, the holder 62 is rockingly mounted in the base 51 and is journalled therein by the bearing ring 65. The transmission housing 62 then is similar to a ball and socket joint or, in other words, the holder 62 is supported by the base 51 for limited free swinging movement in any direction. The bearing ring 65 journals the holder 62 but, at the same time, offers some resistance to swinging movement due to the compression applied to said bearing ring by the clamping band 67. Since the band 67 is adjustable, the bearing ring compression can be varied and increased if required to compensate for wear of the resilient bearing material or the sliding parts of the housing 50. A set screw 74 is fitted to the outer edge 53 of the case so as to engage the sidewall 63 of the holder, this arrangement enabling the holder 62 to be secured in any selected position to which it may be turned within the base 51.

The inner end 76 of the substantially spherical holder is cut off so that it is open and is spaced a short distance from the closure disc 56. At the opposite or outer end, the sidewall 63 curves inwardly towards an outer cylindrical neck 78 which provides the holder with an outer end opening 79. The inner surface of the sidewall 53 is fitted with a bracket 80 and secured to this bracket is an inwardly dished reflector 81. Bracket 80 supports reflector 81 so that the latter member extends across the center of the holder 62 near to the inner end 76 and to the opening 79. Reflector 81 is fitted with a centrally disposed socket 83 and fitted to this socket is an incandescent lamp 84. The lamp 84 is electrically connected by a wire 85 into the circuit 25, the wire extending through a grommet 86 mounted on the wall 52 near the flange 55.

The neck 78 is provided with a fine thread 90 and mounted on this threaded portion of the holder 62 is a sleeve 91 in which a lens 92 is suitably mounted. Lens 92 is a positive or converging lens which is supported by the sleeve 91 to extend across the outer end opening 78 in alignment with the lamp 84. A set screw 93 is fitted to the sleeve 91 whereby to engage the neck 78 and lock said sleeve against rotation. The sleeve 91 has a reduced outer end 94 which is threaded as at 95 to receive an annular cap 96. Supported between the cap 96 and the outer end of the sleeve 91 so as to extend across and form a second end closure for the outer end opening 79, is an infra-red light filter 98.

The receiver generally indicated at 31 is shown in FIG. 4 to be of substantially the same construction as the transmitter 30 and, for convenience, the corresponding parts of said receiver are designated by the same reference numeral and the identifying letter A. The bracket 80A of the holder 62A supports a transverse arm 100 and mounted on this arm is a photoelectric cell 101. The photocell or, as it is commonly called, electric eye 101 is positioned in the center of the housing 50A in alignment with the positive lens 92A and infra-red filter 98A of the receiver 31. A wire 103 connects and photocell 101 into the circuit 25.

When the apparatus has been secured to the wall 14 as previously described, circuit 25 is plugged into a wall outlet for other source of power, not shown, and the switch 27 is closed. Switch 44 is moved to the dotted line position of FIG. 1 to connect the lamp 43 into the circuit 40 and the unit 24 then is ready to be adjusted so as to guard the room 11 against intruders. This adjustment is done with the caps 96 and filters 98 removed from both the transmitter 30 and receiver 31. First a suitable line is selected for the light beam 36 to travel from the point of projection through the mirrors 33 and 34 and back to the receiver 31. Both mirrors of course are adjustably mounted so that they can be raised or lowered as required and turned to any desired angle with respect to the walls 15 and 16. The holder 62 is swung about the base 51 and the mirrors 33 and 34 are turned so the beam 36 being projected from the transmitter cuts across the windows 19 and 20 and door 21 at an appropriate level before being returned to the receiver 31. By moving the holder 62A about in the base 51A, the receiver is properly aligned so that the beam 36 enters the opening 79A and strikes the photocell 101. Sleeve 91 is adjusted to focus the lens 92 as required and similarly the lens 92A is adjusted by a movement of the sleeve 91A so that the beam 36 falls directly on the electrode of the photocell 101. Once the final adjustments to the several parts have been made and the desired focusing has been achieved, the set screws 74 and 74A as well as 93 and 93A are tightened to lock the parts in their set positions.

The apparatus is now ready to be tested, and this can be done by passing an object through the beam 36 so as to complete the circuit 40 and light the lamp 43. This lighting of lamp 43 signifies the apparatus is in proper working order and at this stage, the rheostat 28 can be adjusted to reduce the output of the transmitter 30 to a desired low level. The light intensity of the beam 36 is reduced so that it is sufficiently sensitive to detect smoke but at the same time care is taken not to reduce it to a point where a flying insect or a piece of blown paper will set off the alarm. Once it is determined the apparatus is operational, the switch 44 is moved to the solid line position of FIG. 1 whereupon the lamp 43 is cut out of the circuit 40 and the bell 42 is placed therein. The two infra-red filters 98 and 98A are then fitted to the transmitter and receiver by replacement of the caps 96 and 96A. The filter 98 serves to remove the visable rays of light from the beam 36 and the filter 98A blocks all room light or sun light which might otherwise reach and influence the photocell 101. Thus, no visual indication is given of the presence of the light beam 36.

As previously mentioned, the alarm bell 42 will ring any time an intruder walks through the door 21 or enters one of the windows 20 or 19. The control unit 24 has a holding relay, not shown, which causes the bell 42 to continue to ring once the beam is interrupted and the alarm will sound until the householder enters the room 11 and reopens the hidden switch 27. Should a fire occur in the room 11, the smoke it produces will also cut the beam 36 and trigger the alarm.

From the foregoing it will be apparent there is provided a simple yet extremely effective alarm system which is particularly well suited for use in the home or in small offices or the like. The degree of control of the beam provided by the transmitter and receiving housings and the ability to precisely focus the light rays ensures that the alarm is almost foolproof and is completely reliable. By means of the rheostat 28, the wattage of the lamp 84 can be reduced from a maximum which preferably is 5 watts (24 volts) to a minimum of say, 2 watts thereby eliminating excess heat in the housing 51 so as to extend the operating life of the light transmitting bulb 84. At the same time, light intensity is reduced to a point where the beam 36 is sufficiently sensitive to detect small amounts of smoke so the unit will operate effectively as a fire alarm. The two precision made lenses of the transmitter and receiver make it possible to transmit the light beam over a distance in excess of 140 feet with the light beam being rendered invisable by the use of the infra-red filters. Tests have proven that an object of one-fourth inch in diameter can pass through the light beam without setting off the alarm and therefore a small flying insect will not cause a false alarm. The alarm apparatus can be quickly and easily installed and the light beam can be properly focused in a very short time due to the swivel action provided by the projector and receiver housings.

Claims

We claim:

1. Alarm apparatus comprising a base adapted to be attached to a surface, a hollow holder supported by the base for limited free swinging movement in any direction, a resilient bearing ring interposed between the base and the hollow holder, a clamping plate secured to the base to compress the resilient bearing ring against the hollow holder, a neck formed on the hollow holder remote from the base and defining an outer end opening, a light beam transmitting and receiving circuit including an electric element supported within the hollow holder, a sleeve threadedly secured to the neck, a lens carried by the sleeve to extend across the outer end opening and focus the light beam, a light filter supported by the sleeve adjacent the lens to filter out visible rays of the light beam, and including an alarm circuit adapted to be energized when the light beam is broken; said alarm circuit including an audible signalling device, a visual signalling device, and a two-way switch operable to disconnect a selected one of said devices from said alarm circuit.

2. Alarm apparatus as claimed in claim 1, and including locking means for securing the hollow holder in a selected position on the base.

3. Alarm apparatus as claimed in claim 1, and including means for securing the sleeve against rotational movement on the neck.

4. Alarm apparatus as claimed in claim 1, in which said light beam transmitting and receiving circuit includes a rheostat for controlling the intensity of the light beam.