GB2370680A

GB2370680A - An electromagnetical door chime with two inputs

Info

Publication number: GB2370680A
Application number: GB0121507A
Authority: GB
Inventors: Gilbert Hopfner; Sebastien Guilmont
Original assignee: Legrand SA; Legrand SNC
Current assignee: Legrand SA; Legrand SNC
Priority date: 2000-09-05
Filing date: 2001-09-05
Publication date: 2002-07-03
Anticipated expiration: 2021-09-05
Also published as: FR2813688A1; GB2370680B; GR20010100406A; GB0121507D0; FR2813688B1

Abstract

A two-entry electromechanical door chime includes an actuator (8) having a coil (10) and a mobile core (12), and two blades (4, 6) disposed on respective opposite sides of the actuator. The chime is associated with two push-buttons (26, 28). One push-button (26) is connected to the chime via a device (16) for modifying the frequency of the force generated by the magnetic field applied to the mobile core (12).

Description

i.. \4,,. A two-entry electromechanical door chime The present invention

relates to a two-entry electromechanical door chime.

5 An electromechanical door chime generally includes an actuator acting on two separate blades. The actuator includes a coil at the centre of which is a core that oscillates when the actuator is fed with an alternating electrical current. The two blades are on respective 10 opposite sides of the actuator and each is substantially perpendicular to the direction of oscillation of the core. If a house, or some other place, has two separate entries, it is preferable to be able to distinguish the 15 sound generated by the chime according to the entry at which a visitor is present.

A first solution is to use two completely separate chimes at the two entries generating different sounds.

However, there are also chimes that can be actuated by 20 two pushbuttons at two different places, each push-button generating a different sound. This kind of chime generally includes two actuators and a stop limiting the travel of the core of one of the actuators.

When the first actuator is operated its core strikes the 25 two blades in succession and produces a "ding-dong" sound. When the second actuator is operated its core strikes only one blade and is then stopped by the stop.

The second actuator therefore produces only a "ding" sound. 30 The prior art devices are costly because, although

they use a common casing, they require two complete actuators and a stop.

An object of the present invention is therefore to provide an electromechanical door chime that can be 35 actuated by two push-buttons at different places, each

push-button generating a different sound, at a lower unit cost than prior art chimes of this kind. The chime

advantageously uses only one actuator.

To this end, the present invention proposes a two 5 entry electromechanical door chime including an actuator having a coil and a mobile core and two blades disposed on respective opposite sides of the actuator, and the chime is associated with two push-buttons.

In accordance with the invention, one push-button 10 is connected to the chime via a device for modifying the frequency of the force generated by the magnetic field

acting on the mobile core.

In this way it is possible to vary the frequency of the force generated by the magnetic field so that it

15 approximates the natural mechanical frequency of oscillation of the mobile core. The excitation frequency of the core is then closer to the natural frequency of the mechanical oscillating system and the amplitude of the oscillations is increased. It is then sufficient to 20 position one blade so that the core strikes the blade on each large-amplitude oscillation corresponding to the modified frequency, whereas the blade is not struck for an amplitude corresponding to an unmodified frequency In this way, operating the push-button associated with the 25 device for adapting the frequency produces a ringing sound and operating the other push-button produces a chime sound.

This solution enables the use of only one actuator.

In a preferred embodiment, the device for modifying 30 the frequency of the force generated by the magnetic field includes a diode and divides that frequency by 2.

This solution has the great advantage of low unit cost.

If the device for modifying the frequency of the force generated by the magnetic field affects the power

35 of the actuator, means for reducing the power of the

actuator when the second push-button is operated are advantageously provided so that the power is substantially the same whichever pushbutton is operated.

The loudness of the sound generated by the chime is then S the same regardless of which push-button is operated. In a preferred embodiment the device for reducing the power of the actuator includes a resistor. This solution has the advantage of low unit cost.

Another way to reduce the power of the actuator is lO for the coil to have two inputs, with a first input for producing the maximum power from the coil connected to the first push-button and a second input for providing a reduced power connected to the second push-button.

The following description, which is given with

15 reference to the accompanying drawings, explains the objects and advantages of the invention. It is clear that the description is given by way of example only and has

no limiting character.

Figure 1 is a perspective view of a two-entry chime 20 in accordance with the invention, without the cover.

Figure 2 is an electrical circuit diagram of a first embodiment of a chime according to the invention, and Figure 3 is a circuit diagram corresponding to the 25 figure 2 circuit diagram for a different embodiment.

Figure 1 shows a chime in accordance with the invention. The chime includes a base 2 inside which are two blades 4 and 6 and an actuator 8. In the conventional way, the base is parallelepiped-shaped and the blades 4 30 and 6 are disposed along its longitudinal edges. The actuator 8 is between the two blades 4, 6. The actuator has a coil lO and a core 12. For clarity, figure 1 shows only the former of the coil 10 and not the winding. The core 12 is spring-loaded into its rest position by a 35 spring 14. This kind of structure is known to the skilled

person. When a current flows through the coil, a force is exerted on the core that tends to move it longitudinally relative to the coil. The blades 4 and 6 are perpendicular to the direction in which the core moves.

5 Figure 1 also shows a diode 16 and a resistor 18, both mounted on a printed circuit 20. In this embodiment three connecting terminals 22 are provided for connecting the chime to two push-buttons, not shown. Electrical contacts 24 make the electrical connection between the 10 printed circuit 22 and the actuator 8.

Figure 2 is the electrical circuit diagram of the chime shown in figure 1. The electrical circuit diagram includes the coil 10, the resistor 18 and the diode 16.

The electrical circuit diagram also shows the 15 push-buttons 26 and 28. The chime as such as symbolised by a dashed line rectangle. It is supplied with electrical energy from a power supply 30 and possibly a transformer 32.

The figure 2 circuit diagram shows that the first 20 push-button 26 is connected in series with the diode 16 and that the second push-button 28 is connected in series with the resistor 18. The coil 10 is connected in series with this combination.

This is how the device shown works: The chime is 25 supplied with alternating current at a frequency of 50 Hz. If the first push-button 26 is operated, the coil 10 is in series with the diode 16. The diode halfwave rectifies the sinusoidal signal energizing the coil 10.

The frequency of the force generated by the magnetic 30 field, which is 100 Hz in the absence of the diode, is

then divided by 2. This generates at the core 12 a mechanical oscillation of large amplitude if the push-button 26 is held down. This oscillation causes the mobile core 12 to strike the blade 6 periodically and 35 thereby generate a ringing effect. When the push-button

26 is released, the spring 14 returns the core to its rest position and the core then strikes the blade 4 once.

The sound generated by the chime is therefore a "dring dong" sound.

5 As indicated above, the diode 16 reduces the frequency of the force generated by the magnetic field

acting on the core 12. This reduction in the frequency is such that the frequency of the force generated by the magnetic field is closer to the natural frequency of

10 oscillation of the core and spring system. This increases the amplitude of the movement of the core 12. The blade 6 is of course disposed so that the core strikes the blade 6 on each oscillation. This produces the ringing effect ("doing" sound).

15 If a user operates the second push-button 28, the coil 10 is in series with the resistor 18. The resistor reduces the power of the actuator 8. Accordingly, the core 12 strikes the blade 6 a first and only time, but remains at a distance from the plate as the core 12 20 oscillates about its equilibrium position. When the push-button 28 is released, the electrical circuit is interrupted and the return spring 14 returns the core 12 to its rest position. At this time the core 12 strikes the blade 4. The sound generated by the chime when the 25 push-button 28 is pressed is therefore a "ding-dong" sound. The distance between the core 12 when at rest and the blade 6 is of course such that a ringing effect is produced if the first push-button 26 is operated and a 30 chime effect is produced if the second push-button 28 is operated. This is possible because in the former case the amplitude of oscillation of the core 12 is increased and in the latter case the power of the actuator is reduced by the resistor.

35 Figure 3 shows a variant of the chime shown in

figures 1 and 2. Here the coil 10 has two inputs. A first input is connected to the first push-button 26 and produces the maximum power from the actuator 8. Only some of the turns of the coil then carry the electrical 5 current. The second input is connected to the second pushbutton 28. It produces only a reduced power from the actuator 8. All the turns of the coil 10 then carry the current. The circuit also includes the voltage source 30 and possibly the transformer 32. Here the diode 16 is 10 also connected in series with the first push-button 26 but the second push-button 28 is connected in series with the turns of the coil 10 that carry an electrical current only if the second push-button 28 is operated. These turns are identified by the reference number 34 in figure 15 3. This device operates in exactly the same way as the previous device. Also, the amplitude of oscillation of the core 12 is greater if the first push-button 26 is operated. A portion of the coil 10 is in series with the 20 diode 16. The frequency of the force generated by the magnetic field is then 50 Hz. If the second push-button

28 is operated, the frequency of the force generated by the magnetic field is 100 Hz and the whole of the coil

10, including the turns 34, is in series with the second 25 push-button 28. The power of the actuator is therefore reduced in this latter case, as explained above.

Both embodiments described above enable two different sounds to be produced with a single actuator.

The modifications required compared to a simple 30 electromechanical door chime generating only one sound are minor. It suffices to add a diode and a resistor and possibly to modify the distance between the core at rest and the blades. These modifications are easy to apply and do not involve a high additional cost. This produces a 35 two-entry electromechanical door chime of relatively low

unit cost, comparable to the unit cost of a simple chime.

The scope of the present invention is not limited to the details of the embodiments described above by way of non-limiting example and, on the contrary, extends to 5 modifications within the scope of the following claims that will be evident to the skilled person.

Thus the diode described above could be replaced by some other device for varying the frequency of the force generated by the magnetic field acting on the core. The

10 skilled person knows of electronic circuits for varying the frequency of an electrical field.

The additional resistor or the coil with two inputs is optional. It is equally possible to use a coil with two inputs at the same time as a resistor connected in 15 series with a push-button. Other means can equally be used to reduce the power of the actuator when the second pushbutton is operated.

Claims

1. A two-entry electromechanical door chime including an actuator having a coil and a mobile core, and two blades disposed on respective opposite sides of 5 the actuator, the chime being associated with two push-buttons, wherein one push-button is connected to the chime via a device for modifying the frequency of the force generated by the magnetic field applied to the

mobile core.

10

2. A two-entry electromechanical door chime according to claim 1, wherein the device for modifying the frequency of the force on the mobile core generated by the magnetic field includes a diode and divides that

frequency by 2.

15

3. A two-entry electromechanical door chime according to claim 1, including means for reducing the power of the actuator when the second push-button is operated.

4. A two-entry electromechanical door chime 20 according to claim 3, wherein the means for reducing the power of the actuator include a resistor.

5. A two-entry electromechanical door chime according to claim 3, wherein the coil has two inputs, a first input produces the maximum power from the coil and 25 is connected to the first push-button and a second input produces a lower power and is connected to the second push-button.

6. A two-entry electromechanical door chime substantially as hereinbefore described with reference to 30 the accompanying drawings.