GB2301941A - Luminous pushbutton for intercom and video-intercom systems - Google Patents

Abstract

A luminous pushbutton for intercom and video-intercom systems comprises a button 2 of transparent plastics material and metal shell 1 covering the outer surface of the button 2 and having aperture 3 from which light emerges. The light is emitted by a light source contained in a container 8 for the electrical contacts of the pushbutton and is conducted towards the aperture 3 of the button 2 by a diffuser element 7 housed in a cavity 15 in the button 2. The light transmitted through the button aperture 3 also illuminates a name plate (20, Fig 1) positioned alongside the button 2.

Description

LUMINOUS PUSHBUTTON, IN PARTICULAR FOR PUSHBUTTON UNITS OF INTERCOM AND VIDEO-INTERCOM SYSTEMS This invention relates to a luminous pushbutton, in particular for intercom and video-intercom systems.

In their most common constructions, pushbutton units are flushmounted in the wall or rest on the wall at the external stations of the intercom or video-intercom system, the pushbuttons (to the sides of which there are the relative strips carrying written names) being mounted behind a plate and projecting outwards through an adequate hole via a plunging button which is pressed with the finger.

It is known to insert a number of filament lamps into the station to illuminate both the pushbuttons (constructed of transparent material) and the name-strips (of perspex).

Said lamps may remain lit uninterruptedly or may be lit (by a manual or automatic command) only in the case of poor or insufficient illumination of the pushbutton unit by natural light (due to the particular installation position or during the night, if the pushbutton unit is located at an external station).

However, if the number of pushbuttons and strips (carrying written names) is large or if several standard pushbutton unit modules are combined, it is extremely difficult to sufficiently illuminate the entire station for reading the names and making the call.

In this respect, the number of lamps required would be decidedly greater than the number of pushbuttons present, so as to cover a large part of the front surface of the station.

A solution to this problem is to use pushbuttons in which the button is in the form of a luminous gem.

A filament or neon lamp, powered at low voltage (typically 24 Volts) via a suitable incorporated transformer or resistor, is contained within the gem.

The luminous gem is usually of thermoplastic material, available in various colours and different forms (numbered, timed, with a mushroom button, flat, projecting, pull-type, lever-type, palmtype), of continuous or intermittent operation, and can be switched on manually or automatically.

However, again in this case the solution adopted is very costly in consideration of the fact that the number of gems and lamps is equal to the number of pushbuttons, further lamps being required for illuminating the name-strips.

Moreover, the structure of the pushbutton unit is fragile because the optical night identifier devices (gems or lamps) are of relatively large size (corresponding substantially to the diameter of the pushbutton) and are located below the root plate.

An object of the present invention is to obviate the aforesaid drawbacks, in particular for pushbutton units of intercom and video-intercom systems, which combines in one and the same structure the advantages of simple and rapid operation with uniform illumination sufficient not only for all the pushbuttons present but also for the corresponding strips carrying the written names, in the case of insufficient natural light.

A further object is to provide a pushbutton structure which maintains strength and rigidity (for example, in the case of antivandalism pushbutton units, against impact and tampering) while comprising luminous optical identifier devices positioned in the pushbuttons.

A further object of the luminous pushbutton of the present invention is to provide a structure which preserves both its appearance and its operability (in terms of operating life, reliability and manufacturing and operating costs).

A further object of the invention is to provide a luminous pushbutton of simple and economical construction, which has a low electrical energy consumption compared with the known art (and hence a substantially lower running cost) and which does not require the use of complex techniques or costly electrical and electronic components.

These and further objects are attained by the luminous pushbutton of the present invention, in accordance with claim 1.

Advantageously, the luminous pushbutton of the invention comprises a button of transparent plastics material which outwardly diffuses light originating from light sources (consisting typically of underpowered or long-life filament lamps or LEDs), which are located within the electrical contact container.

Reference is made-herein to pushbutton units of modular type, in which several modules containing the electrical and electronic components of the entire intercom or video-intercom system are assembled together within the internal housing of the station; with each module there corresponds at least one pushbutton (typically each module can house the electrical circuits of 1, 2 or 3 pushbuttons), provided with a single electrical contact and relative strip carrying the written name.

The light emitted by the light sources (the number of which is fixed for each pushbutton unit and depends on the number of modules and pushbuttons present) is perceived externally via a central aperture in a metal shell, which covers the button and projects from the front plate of the pushbutton unit.

The diffusion of the radiation emitted by the light sources, occurring through the diffuser element (positioned within a deepdrawn cavity in the button) and through the constituent material of the button results in sufficient illumination both of the pushbuttons and of the relative name-strips, even in the case of poor natural light.

Usually in such a case a filament lamp is used, or a matrix consisting of a predetermined fixed number of LEDs for illuminating a pushbutton unit comprising up to 8 pushbuttons.

The operation of the light sources is continuous, in consideration of the fact that the electrical energy consumption for illumination is negligible compared with the electrical energy consumption in powering the intercom system.

The metal shell covering the button is of hemispherical form, so as to immediately draw the attention of the user and allow easy and rapid operation.

The fact of limiting the dimensions of the aperture through which the light emerges for identifying the pushbutton and the relative name-strip results in a robust and solid structure of the pushbutton unit, in particular of anti-vandalism pushbutton units, in the case of impact or tampering attempts, although maintaining aesthetic and operability characteristics intact. In addition, localizing the radiation onto a small surface increases the density of the energy transmitted outwards compared with known arrangements.

Finally, the pushbutton shell has a diameter greater than the pushbutton slide seat, and is bent over and upset onto the edges of the button along the horizontal plane of the plate by a clinching operation, in order to achieve a good durable seal between the metal covering and the plastics material of the button.

Further characteristics and advantages of the invention will be more apparent from the ensuing description of a preferred but not exclusive embodiment of the luminous pushbutton, illustrated by way of non-limiting example on the accompanying schematic drawings, in which: Figure 1 is a broken front view of a pushbutton unit, comprising a plurality of luminous pushbuttons and relative name-strips; Figure 2 is a broken section through a luminous pushbutton of the invention in its rest position, and also showing that part of the plate of the pushbutton unit about the pushbutton.

In the aforesaid figures, the reference numeral 10 indicates the luminous pushbutton overall, 20 indicates the strips carrying written names, and 5 indicates the front plate of the pushbutton unit.

The pushbutton 10 comprises a hemispherical shell 1 of metal (typically stainless steel or chromium-plated brass) with a central aperture 3, from which the button 2 of transparent plastics material projects.

From Figure 1 it can be seen that the diameter of the pushbutton 10 is less than the diameter of its housing seat 18, formed in the plate 5, so that the pushbutton 10 can slide inwards.

The shell 1 is sealed onto the button 2 by a clinching operation at the ends of the diameter of the hemisphere. so that dust or other atmospheric agents cannot penetrate internally.

With particular reference to Figure 2, the reference numeral 4 indicates two plastic bellows gaskets connected at one end to the plate 5 and at the other end to the button 2.

In correspondence with the seat 18 for the pushbutton 10, the plate 5 is curved downwards to house the shell 1.

The reference numeral 6 indicates two metal structures positioned below the plate 5 and symmetrical about an imaginary axis passing vertically through the centre of the aperture 3 and to which the gaskets 4 are attached, the reference numeral 8 indicating a container internally comprising the light sources (not shown) and the electrical contacts and terminals (not shown) for connection to the intercom and/or video-intercom system.

Finally, the reference numeral 7 indicates a T-shaped diffuser element of transparent plastics construction, contained within a cavity 15 in the button 2 (this cavity being obtained by deep drawing the hole housing the diffuser element 7).

The diffuser element 7 communicates with the light sources positioned in the container 8.

The pushbutton 10 and button 2 move downwards when pressed by the finger, from the rest position to the operating contact position, to thrust the diffuser element 7, which is slidable and can act on the contacts situated in the container 8.

In their downward movement, the button 2 and diffuser element 7 are guided by the two bellows gaskets 4, the purpose of which is to damp the striking of the shell 1 and button 2 against the structure 6 internal to the plate 5.

Said gaskets 4 also protect the button 2 and structure 6 of the pushbutton 10 against moisture and protect the mechanism by hindering the entry of atmospheric agents such as rain, dust and the like.

The shell 1 is pressed so that it becomes inserted in line with the plate 5 into the housing seat 18 to the position in which operational contact is made, to hence call the various floors.

On releasing the pushbutton 10 the gaskets 4, resting against the structure 6 and against the button 2 and completely compressed, restore the rest position (with the shell 1 projecting from the horizontal plane of the plate 5), by urging the diffuser element 7 and button 2 upwards.

The return travel of the diffuser element 7 is limited by a collar, which engages the button 2 and the structure 6.

The light emitted-by the light sources is diffused, by reflection and transparency, from the light sources contained in the container 8, through the diffuser element 7 and button 2 (both constructed of transparent plastics) and to the outside via the aperture 3 (also of transparent plastics) of the shell 1.

Because of the fact that the constituent plastics materials of the diffuser element 7 and button 2 contain numerous inclusions and as the surface of separation between said materials is rough, disordered reflection and refraction of the light beam take place, as a result of which the materials appear turbid even if consisting of transparent substances.

Light diffuses towards the aperture 3 because of the disordered reflection by the particles of the constituent materials of the diffuser element 7 and button 2, by partial refraction in all directions, and finally because of the transparency of the two plastics materials.

The material particles in particular diffuse short-wavelength electromagnetic radiation. The greater the wavelength the better the electromagnetic waves pass by the obstacle formed by each particle.

Hence, for usual particle dimensions, a white light beam diffuses mainly bluish light. This is one of the reasons why it is preferable to use as light source a matrix of LEDs (usually of gallium arsenide type) of slightly shaded colour compared with filament lamps.

Another advantageous characteristic of the invention is that the light sources (lamps or LEDs) are positioned within the interior of the intercom and/or video-intercom system and not in proximity to the front plate of the pushbutton unit. This means that the external structure of the pushbutton unit, if constructed of robust materials for particular requirements (for example for anti-vandalism pushbutton units protected against impact and tampering), is not weakened by the presence of fragile plastic or glass elements such as optical night indicator devices for the pushbuttons and name-strips.

It is apparent that the materials and dimensions of the invention as described heretofore, as illustrated on the accompanying drawings and as hereinafter claimed, can be chosen at will according to requirements.

It is also apparent that all details can be replaced by others technically equivalent and that numerous modifications can be made by the expert of the art to the luminous pushbutton of the present invention, but without leaving the scope of protection of the following claims.

Claims (10)

1. A luminous pushbutton (10), of the type particularly for intercom and video-intercom pushbutton units, comprising at least one button (2) which partly projects to the outside of the plate (5) of said pushbutton unit and is partly inserted into a housing seat (18), at least one metal shell (1) which covers the outer surface of said button (2), a structure (6), internal to the plate (5), which supports said plate (5), and at least one container (8) in which the electrical contacts and terminals for connection to intercom and/or video-intercom systems are positioned, characterised in that said button (2) is formed of optically conducting material and comprises at least one deep-drawn cavity (15) housing at least one diffuser element (7) formed of optically conducting material and connected to at least one light source, so that the radiation emitted by said source is diffused by said diffuser element (7) and by said button (2) towards the outside of said pushbutton (10) via an aperture (3) in said shell (1), said aperture (3) being formed of the same optically conducting material as that forming said button (2), said diffused radiation being able to illuminate a plurality of strips (20) carrying written names and of pushbuttons (10) of said pushbutton unit.

2. A luminous pushbutton (10) as claimed in claim 1, characterised in that said light source is positioned in said container (8).

3. A luminous pushbutton (10) as claimed in claim 1 or 2, characterised in that said light source is an LED.

4. A luminous pushbutton (10) as claimed in claim 1 or 2, characterised in that said light source is a filament lamp powered at low voltage via transformers or resistors.

5. A luminous pushbutton (10) as claimed in claim 1, characterised in that said button (2) and said diffuser element (7) are formed of transparent plastics material or luminescent and/or electroluminescent material.

6. A luminous pushbutton (10) as claimed in claim 1, characterised in that said shell (1) is of hemispherical shape, with a diameter greater than the diameter of said seat (18) housing said button (2).

7. A luminous pushbutton (10) as claimed in claim 1 or 6, characterised in that said shell (1) is bent over and upset, by a clinching operation, onto said button (2) in correspondence with the ends of the diameter of said shell (1), in order to form a seal against atmospheric agents.

8. A luminous pushbutton (10) as claimed in claim 1, characterised in that said pushbutton (10) comprises a plurality of bellows gaskets (4) fixed to said button (2) and to said internal structure (6), so as to return said pushbutton (10) into its rest position when said pushbutton (10) is released by the user after having been put into its operating contact position by being pressed from the outside by the user.

9. A luminous pushbutton (10) as claimed in claim 8, characterised in that said gaskets (4) are of plastics construction.

10. A luminous pushbutton (10) in accordance with the present description and the accompanying drawings.