GB2604181A

GB2604181A - Method and apparatus for sterilising surfaces

Info

Publication number: GB2604181A
Application number: GB2102828.7A
Authority: GB
Inventors: Atkinson Neil
Original assignee: Siemens Mobility Ltd
Current assignee: Siemens Mobility Ltd
Priority date: 2021-02-26
Filing date: 2021-02-26
Publication date: 2022-08-31
Also published as: GB202102828D0

Abstract

A method for sterilising a surface of an article 12 wherein a ultraviolet-C light-emitting diode (LED) 28 emits UV-C light through the material of the article 12 and out of the surface. The article 12, preferably a push button 10 or switch, has a first surface arranged for user access and an opposite second surface arranged to receive the UV-C light from a UV-C LED 28. The UV-C light traverses the UV-C transparent article 12 to emerge on the first user contactable surface. There may be a timer which activates the UV-C LED 28 only after a predetermined length of time has elapsed since operation of the button 10 or switch. In one embodiment, the button 10 is within an enclosure such as a shroud (30, fig. 2) or cover (40, fig. 3). Within these enclosures, there may be a UV-C LED 42 which irradiates all surfaces.

Description

Method and Apparatus for Sterilising Surfaces There has been much interest of late in sterilising surfaces, to remove traces of bacteria and viruses, since it is believed that bacteria and viruses can remain active on surfaces for several days, and to thereby provide a viable route for transmission from one individual to another.

This is particularly the case for high-traffic surfaces, such as access control buttons in public places. Such access control buttons may include buttons used to request opening of doors on trains or buses; or to request change of signals at a pedestrian crossing; or to request the opening of doors to, and within, buildings.

Other surfaces which are touched by many people in rapid succession include payment pad buttons, light switches, door handles and latches.

It is known that UV light, particularly the UV-C and far-UVC parts of the spectrum, may be directed at surfaces to kill bacteria and viruses. This is typically carried out by directing UV-C lamps at large surfaces, where one can be sure that no people are nearby, within reach of the used UV-C.

Known arrangements for sterilising surfaces involve light directed onto surfaces from an external source.

Examples of such large-scale installations are mentioned in https//www.bbc.com/future/articie/202r, 327-can-you-kill-coronavirns-with-uv-light.

The present invention aims to provide methods and equipment for providing sterilisation of surfaces by irradiation with UV light, between users, in a rapid and safe manner.

The above, and further, objects characteristics and advantages of the present invention will become more apparent from the following description of certain embodiments thereof, in conjunction with the accompanying drawings, wherein: Figs. 1A-4 schematically illustrate respective embodiments of 5 the present invention.

In an example embodiment of the invention, described with reference to Fig. 1A, a push button or switch is arranged to be sterilized by application of UV-C lighting after, or before, 10 each use.

Small UV-C LEDs have recently become available, and these components will be used in example embodiments of the invention to be described below.

In a preferred embodiment, a UV-C LED is embedded into a transparent button or switch, to provide a sanitising effect. It is important to ensure that the emitted UV-C light cannot reach the eyes of a bystander, as damage may thereby be caused.

Some wavelengths of UV-C should equally be kept away from skin of bystanders or users, although it is understood that some wavelengths of UV-C may usefully be applied to a user's skin to provide direct sanitisation of the skin.

Fig. 1A shows an example cross-section of an illuminating switch. However, here, the illuminating switch is arranged such that it illuminates after, or before, operation of the switch, or both, rather than the conventional arrangement in which the switch illuminates synchronously with operation of the switch.

Figs. 1B, 1C show similar switches, which may be regarded as variants of the switch of Fig. 1A.

Figs. 2-3 illustrate more complete embodiments of the invention, where a surround or cover of some type is provided to ensure that UV-C light used to sterilise the switch is not directed into the eyes, or onto the skin, of a passer-by.

In a preferred embodiment, switching on of the UV-C LED will only happen some time after the button has been used, which may be arranged by a timer measuring a predetermined length of time after the removal of the user's finger to ensure that there is not a finger on the button at the time the UV-C is on.

The button would be housed under a cover/shroud, or within 10 something like a tube to ensure that UV-C light can't shine into the eyes of a user or a bystander.

In Fig. 1A, a cross-sectional view of a pushbutton 10 according to an embodiment of the invention is shown. Many other designs of pushbutton are possible, as will be apparent to those skilled in the art. While the illustrated pushbutton relies on a spring return, other examples may use a resilient diaphragm. The pushbutton 10 is approximately rotationally symmetrical about a vertical axis. A button 12 is biased away from a backing plate 14 by a spring 16 or equivalent. A ferrule 18 retains the button and defines a range of movement of the button. The ferrule is mechanically retained to the backing plate 14 by any suitable arrangement. Respective electrical contacts 20, 22 are arranged such that they are brought into electrical contact with one another by operation of the button 12. Respective electrical conductors 24, 26, connected to electrical contacts 20, 22, are brought out of the pushbutton for connection to an external circuit. According to an aspect of the invention, a UV-C LED 28 is provided within the pushbutton, oriented to illuminate the button 12. Electrical leads 30, 32 are provided, leading out of the pushbutton 10. Typically, in an illuminated pushbutton, the illumination is activated or deactivated at the same time that the button 12 is pressed. In the present invention, it is required that the LED is activated only some time after a user's finger has withdrawn from the pushbutton. This may be arranged by circuitry connected to electrical leads 24, 26, 30, 32 but not illustrated. Suitable circuitry would be readily apparent to those skilled in the art.

Button 12 is constructed of a material which is transparent to 5 the UV-C light generated by LED 28. Preferably, ferrule 18 is also constructed of a material which is transparent to the UV-C light generated by LED 28.

A comparable arrangement, as will be apparent to those of skill 10 in the art, may replace the push button assembly with a rocker switch assembly or any other type of switch assembly, or even a mechanical control lever or similar.

According to the illustrated embodiment, a UV-C LED is incorporated into a transparent illuminated button or switch 10, such that the sanitizing means -the UV-C LED -is embedded or incorporated into the button or switch. In use, a user may activate the button or switch in the usual way, and once the user has withdrawn, the UV-C LED may be illuminated. UV-C light will be emitted through the transparent material and so onto, and through, the user-accessible surface.

Fig. 1B represents a variant of this embodiment, in which the UV-C LED 28 is embedded into the material of the pushbutton, so that the UV-C light is generated within the material of the pushbutton, and emerges through the user-accessible surface, so as to sterilise that surface.

Fig. 1C represents another variant of this embodiment, in which the pushbutton 12 is laminated of different materials. In this example embodiment, an outer layer 12a may be of quartz glass while an inner layer 12b may be of FEP (fluorinated ethylene propylene). In this way, the most appropriate material may be used for each layer, according to its 35 properties.

The UV-C LED need not be arranged centrally within the pushbutton, as shown in the illustrations of Figs. 1A-1C, but may be displaced to one side, or angled differently, provided that the UV-C LED is appropriately positioned to direct light through the surface to be sanitised.

In some embodiments, a sensor may be used, such as an infrared sensor, to detect the withdrawal of the user's hand, or a timer may simply detect a certain length of time elapsed since the most recent operation of the button or switch etc. (e.g. three seconds) before activating the UV-C LED. Such a timer may be built into any circuitry to which the button or switch etc. is connected.

For example, Fig. 2 shows an arrangement in which button or switch 10 is provided within a tubular shroud 30. An infra-15 red sensor 32 may be provided within the tubular shroud 30 to detect the insertion of a user's finger, hand, toe, etc to activate the button or switch 10. Once the user's finger (etc.) is detected, operation of the UV-C LED 28 is prevented, until at least the removal of the user's finger is detected.

In some embodiments, following the infra-red detection of the withdrawal of the user's hand, or expiry of an amount of time after a most recent activation of the button or switch 10, which may be taken to signify that the user's hand has been withdrawn, a physical shutter 34 may be closed to ensure that a user has withdrawn before the UV-C LED is activated. Any such shutter should be opaque to the UV-C wavelength used, to reduce the chance of UV-C light reaching the body of a bystander. In examples where a physical shutter 34 is used, the shutter would preferably open automatically before a next user attempts to operate the push button or switch. Further preferably, the structure of the button 12 or switch and the enclosure formed by the shutter should be arranged such that, when the UV-C LED is activated, all surfaces within the enclosure are irradiated by emitted UV-C to such a radiation intensity that all such surfaces are sterilised of bacteria and viruses. It may be preferred to provide further UV-C LEDs within the enclosure to ensure sterilisation of all surfaces of the enclosure.

In other embodiments, for example as illustrated in Fig. 3, rather than having a shuttered enclosure, the button or switch 10 is shrouded by a cover 40, such that a user has to place a hand, or finger, or a foot or toe for that matter, under the cover 40 in order to operate the button or switch 10; and that, once the user has withdrawn from the button or switch 10, the UV-C LED within the button or switch is activated to sterilise the surface of the button or switch, and preferably also the interior of the cover -either by UV-C light emitted from the UV-C LED within the button or switch 10; or by supplementary UV-C LEDs 42 placed to illuminate the interior of the cover 40. Withdrawal of the user from the button or switch may be detected by a detector such as an infra-red sensor 32, or by elapsing of a certain predetermined period of time after a most recent activation of the button or switch 10, as measured by circuitry attached to the button or switch 10, and as will be apparent to those skilled in the art.

Of course, the push button must be made of a material which is transparent to the used UV-C wavelength. Preferably, the whole user-accessible surface of the push button 10 will be transparent and will be back-lit by a UV-C LED according to an embodiment of the present invention.

Fig. 4 shows another example of a pushbutton 50 which may embody the present invention. A case or surround, 52, is provided through a panel 60 and is retained in position with a lock ring 62. A clip-in switch 64 is provided, and contains additional electronics for timing operation of the UV-C LED. UV-C LED 28 is provided, embedded within button 66, and electrically connected to the electronics of the clip-in switch 64. The clip-in switch 64 is retained within a switch housing 68, which is also retained within the case or surround 52. A diaphragm 70 is provided, here retained between surround 52 and switch housing 68. Clip-in switch 64 is a push switch, operated by actuator 72. Button 66 operates a plunger 74 which presses on actuator 72 when button 66 is pressed. Preferably, the button 66 and the plunger 74 are one single moulded FEP part including the UV-C LED 28. The diaphragm 70 is essentially annular, with a hole gripping an indent 76 formed in the plunger.

While illustrating an example embodiment of the invention, the structure of the pushbutton 50 does not form part of the 10 invention.

In use, a user will press on button 66, which will move plunger 74 to press upon actuator 72. This will operate the clip-in switch 64 to make or break electrical continuity between contacts 78 as appropriate. Electronics, not shown, within the clip-in switch 64 will delay operation of the UV-C LED until after the user has withdrawn from the pushbutton 50. This may be by counting down a timer, or using a sensor such as an infra-red sensor to detect that the user has withdrawn. The UV-C LED is operated after the delay to generate UV-C light through an upper surface of button 66, to sterilise the surface which the user contacted. In some embodiments, further UV-C LEDs may be embedded within the material of the surround 52. Those further UV-C LEDs may be operated at the same time as UV-C LED 28 to sterilise the user-accessible surface of surround 52.

Articles other than pushbuttons may be provided with sterilising arrangements according to the invention, and may be sterilised by methods according to the invention. For example, a rocker switch may be equipped with an internal UV-C LED in a similar manner to the pushbutton.

Suitable materials that allow transmission of UV-C include FEP (fluorinated ethylene propylene), which may be a suitable material for injection moulding of buttons and the like, as it shows UV-C transmission with only a 4% loss at 0.25mm thickness. Alternatively a quartz glass could be used. Both of these materials are currently used in existing UV-C sterilization products. Other suitable materials are known, and may become known hereafter, and may be selected according to their properties.

According to a feature of certain embodiments of the present invention, a user touches a first surface of an article to be sterilised, and the UV-C LED emits UV-C light into a second surface of the article to be sterilised, through the material of the article, and out of the first surface. As the UV-C light emerges from the first surface, it sterilises the first surface.

In other embodiments, the UV-C LED is embedded within the 15 article to be sterilised. A user touches a surface of an article to be sterilised, and the UV-C LED emits UV-C light through the material of the article, and out of the surface.

Although the present invention has been described above with 20 particular reference to switches or buttons, the present invention may be applied in similar arrangements to any surfaces which are likely to be touched by a number in rapid succession; and which may be constructed of a which is transparent to UV-C and illuminated from the 25 by a UV-C LED and for which arrangements may be made to of users material interior avoid UV-C from the UV-C LED reaching the body of a user or a bystander. Examples may include door handles, which may be shrouded to protect users and bystanders, controls for operation of machinery; keyboards. Handles used by standing passengers on buses or trains may be equipped with internal UV-C LEDs as described, but such LEDs should only be activated when no users or bystanders are present nearby.

Claims

CLAIMS1. A method for sterilising a surface of an article (12) to be sterilised, wherein a UV-C LED (28) emits UV-C light through 5 the material of the article, and out of the surface.
2. A method according to claim 1, further comprising means (32) for detecting the presence of a user, and activating the UV-C LED after a user has withdrawn from the article.
3. A method according to claim 1, wherein the article is a user-operated button (12) of a pushbutton (10); or is a switch, and a timer serves to activate the UV-C LED only after a predetermined length of time has elapsed since operation of the button (12) or switch.
4. A method according to any preceding claim, wherein the first surface is within an enclosure (30; 40) and the method further comprises irradiating all surfaces within the enclosure by UV-20 C light from at least one LED (42).
5. An article (12) arranged for user access on a first surface; a second surface, opposite the first surface, being arranged to receive UV-C light from a UV-C LED, said UV-C light traversing the article to emerge on the first surface, the article being transparent to the UV-C light.
6. An article according to claim 5, being a button (12) of a pushbutton (10), the UV-C LED being incorporated within the 30 pushbutton (10), oriented to illuminate the button (12).
7. An article according to any of claims 5-6, further comprising a sensor, to detect the withdrawal of a user, or a timer to detect a certain length of time elapsed since the most recent operation of the article before activating the UV-C LED.
8. An article according to any of claims 5-7, further comprising a shroud (30) or cover (40).
9. An article according to any of claims 5-8, further 5 comprising a physical shutter (34) which may be closed to ensure that a user has withdrawn before the UV-C LED is activated.
10. An article according to any of claims 6-7 and 9, arranged such that the structure of the button (12) or switch and the enclosure formed by the physical shutter (34) are arranged such that, when the UV-C LED is activated, all surfaces within the enclosure are irradiated by emitted UV-C to such a radiation intensity that all such surfaces are sterilised of bacteria and viruses.
11. An article according to claim 10, further comprising further UV-C LEDs within the enclosure to ensure sterilisation of all surfaces of the enclosure.