RU2210114C2 - Burglar alarm vibrating-reed sensor - Google Patents

Abstract

FIELD: burglar alarms; blocking vitrified surfaces. SUBSTANCE: vibrating-reed sensor has first case with glass bulb secured therein that accommodates movable contact strip and first and second fixed contact strips normally closed to the latter and used as first and second contacts of sensor alarm circuit, respectively; sensor also has second case that accommodates magnet. EFFECT: enhanced functional reliability of sensor. 1 cl, 1 dwg

Description

 The invention relates to techniques for burglar alarms and can be used to block glazed surfaces, for example, window, display, doorways and other structures.

 Known vibration sensor for alarm devices [1], which comprises a housing with a mounting surface and contact plates fixed in the housing, configured to close them with an electrically conductive ball.

The closest in technical essence and the achieved result to the proposed one is a vibration sensor for security alarm devices [2], comprising a housing with a glass bulb fixed inside, in which normally closed contact plates are placed, the contact planes of which form an angle of 30-60 ^o with the mounting surface of the housing .

 The disadvantage of this sensor is its low functional reliability, which consists in the fact that in case of violation of the mechanical contact of the sensor with the blocked surface, for example, disconnection due to aging of the adhesive joint, accidental or intentional (with the purpose of sabotage) separation, the control of the protected structure is lost without any alarm to the user, which is unacceptable for burglar alarm devices.

 The objective of the invention is to increase the functional reliability of the vibration sensor for alarm devices.

The problem is solved as follows. Into a vibration sensor for burglar alarm devices, comprising a first housing with a glass bulb fixed inside, which contains normally closed first fixed contact plate, which is the first contact of the sensor output signal circuit, oriented at an angle of 30-60 ^o to the mounting surface of the first case, and a movable contact the plate, providing the opening of these plates during impacts on the protected surface, introduced a second case with a magnet fixed inside, and the second one a movable contact plate, placed in a glass flask of the first case, which is the second contact of the sensor output signal circuit and normally closed with the movable contact plate under the influence of the field created by the magnet, when the first and second cases are at a slight distance from each other, the first fixed contact plate made insensitive to the magnetic field, other contact plates sensitive.

 The drawing shows the design of the sensor and a diagram of its installation on a lockable glass.

 The vibration sensor for burglar alarm devices contains the first 1 and second 2 cases installed on the lockable surface of the glass 3 at a distance of 2-4 mm from each other, and in the first case 1 is fixed a glass bulb 4, inside of which a movable contact plate 5 and normally closed with it, the first 6 and second 7 fixed contact plates, which are respectively the first 8 and second 9 contacts of the output signal circuit of the sensor, a magnet 10 is fixed in the second sensor housing 2.

 The sensor operates as follows.

 In the absence of destructive effects on the protected structure and the normal state of the sensor, the housing 1 and 2 of which are located on the surface of the glass 3 at a distance of 2-4 mm from each other, the movable contact plate 5 provides the connection of the first 6 and second 7 fixed contact plates and, therefore, the first 8 and second 9 contacts of the output signal circuit of the sensor. The closure of the plates 5 and 6 occurs due to their elastic deformation with a given contact pressing force, which ensures the sensitivity of the sensor to vibration, and the connection of the plates 5 and 7 occurs under the influence of the field created by the magnet 10.

 The range (2-4 mm) of the distance between the housing 1 and 2 of the sensor is selected as optimal from the following considerations. The lower limit excludes accidental fastening of the sensor housings to each other, for example, when glue flows out of their dimensions during installation on a blocked surface or when the housings become dirty during operation. The upper limit provides an effective effect of the magnet 10 on the contact plates 5 and 7, and therefore, their reliable closure and stable operation of the sensor.

 At the time of the destruction of the glass sheet 3, vibroacoustic vibrations arise in it, propagating in the form of a superposition of longitudinal and transverse waves, which act through the first housing 1 and the bulb 2 on the movable contact plate 5, causing it to oscillate. If the amplitude of oscillations of the plate 5 exceeds the vibration resistance threshold of its normal circuit with the plate 6, then a series of disconnections of these plates occurs and, therefore, the contacts 8 and 9 of the output signal circuit of the sensor open.

 When detaching the sensor from the glass, for example, due to aging of the adhesive joint, accidental or deliberate separation, the inventive sensor, unlike the prototype sensor [2], does not allow loss of control of the protected structure, breaking the contacts of the output signal circuit. It is provided as follows. When the bodies 1 and 2 are removed to a distance of more than 5-10 mm from each other, the intensity of the field of the magnet 10 decreases, which leads to the opening of the plates 5 and 7 and, consequently, the rupture of the electrical connection between the plates 6 and 7, which are the first 8 and the second 9 pins of the sensor output signal circuit.

 Due to the insensitivity of the first fixed contact plate 6 to the effects of a magnetic field and the specified value of the bending stiffness of the movable contact plate 5, the sensitivity of the sensor to impacts resulting in the opening of plates 5 and 6 is practically independent of the intensity of the magnetic field created by magnet 10, as well as or another magnet, for example, when trying to deliberately reduce the sensitivity of the sensor in order to unlock the protected structure.

 The sensor constructed in this way has increased functional reliability, preventing loss of control of the protected structure in case of violation of its mechanical contact with the blocked surface, and also eliminates the possibility of deliberate reduction in sensitivity under the influence of a magnetic field.

 The manufactured prototypes of the proposed vibration sensor ("DRS-2") for burglar alarm devices have successfully passed laboratory tests and trial operation at real facilities, where their high functional reliability was confirmed. Currently, preparations are underway for mass production of such sensors.

Sources of information
1. USSR copyright certificate 318047, cl. G 08 B 13/14, published. 1971.

 2. Patent 2060554 (RF), 1996, MKI 6 G 08 V 13/02, published. 05/20/1996.

Claims (1)

A vibration sensor for burglar alarm devices, comprising a first case with a glass bulb fixed inside, in which normally closed first fixed contact plate, which is the first contact of the sensor output signal circuit, and a movable contact plate, are oriented normally oriented at an angle of 30-60 ^o to the mounting surface of the first case providing for the opening of these plates during impacts on the protected surface, characterized in that a second housing is inserted into it with wipe it with a magnet and a second fixed contact plate, placed in a glass flask of the first case, which is the second contact of the sensor output signal circuit and normally closed with the moving contact plate under the influence of the field created by the magnet, when the first and second cases are at a distance of 2-4 mm from friend, and the first fixed contact plate is insensitive to the magnetic field, the remaining contact plates are sensitive.