GB2473669A - Improvements in sterilization apparatus - Google Patents

Abstract

Sterilisation apparatus comprises a means for directing germicidal energy 16, 24 mounted in a housing 10, means for detecting movement in the target area 17, 18 and a control device 15 for switching the germicidal energy on and off in response to signals from the detecting means. The germicidal energy may be UV light and the detecting means may be an optical sensing or movement sensing mechanisms. The switching means may be arranged to switch the bean on for a length of time after signals from the detection means have ceased, and may include random interval or phase sampling techniques. The device may also include means for emitting a bright light, and be in the form of a free standing unit. The device may be powered by a USB connection.

Description

Improvements in sterlisation apparatus This invention relates to sterilisation apparatus, in particular, though not exclusively, using ultraviolet (UV) light to sterilise data input devices such as keyboards.

The invention provides sterilisation apparatus comprising means for directing a beam of germicidal energy at a target area, means for detecting movement in the targeted area, and means for switching the beam on and off in response to signals from the movement detecting means.

By way of example, embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows one form of sterilization apparatus according to the invention, Figure 2 shows the apparatus of Figure 1 in use in conjunction with a computer keyboard, and Figure 3 is a diagram of the control circuit for the apparatus of Figures 1 and 2.

With the use of computers being practically ubiquitous these days, data input devices such as keyboards represent a potential hazard for spreading infections, for example where the devices may have multiple users and/or are used in unclean environments. The sterilisation apparatus described herein provides for a germicidal agent such as ultraviolet (UV) light to be shone over such devices in a controlled manner in order to sterilise them.

The apparatus shown in Figures 1 and 2 is designed to irradiate a computer keyboard 13 (and/or mouse) with UV light. The apparatus is a free-standing structure, comprising a lamp console 10 held by a column 11 above a base plate 12. The lamp console 10 houses an array of light emitting diodes (LEDs), each of which is arranged to produce a downwardly-directed beam of UV light. In use, the keyboard 13 is placed over the base plate 12 so as to be within the pool of UV light from the LEDs in the lamp console 10 above it.

The lamp console 10 is arranged to be spaced above the base plate 12 by a suitable distance to allow room for a user to operate the keyboard 13.

The number of LEDs and their power are chosen in dependence upon the distance of the lamp console 10 from the base plate 12 to ensure sufficient intensity of UV light. The LEDs themselves will preferably be powered at different current levels to take into account their different distances from the base plate 12. The LEDs at the ends of the array, for example, will typically have to operate at several times the brightness of those that are more centrally placed.

The lamp console 10 comprises an outer shade 14 to shield a user's eyes from the UV light. The LEDs are mounted within the outer shade 14. Here, the shade 14, column 11 and base plate 12 are conveniently formed as an integral unit by bending a flat metallic blank.

Power for operating the LEDs here is conveniently drawn from the computer using a USB connection. Alternative sources of power, such as batteries, could equally well be used.

The LEDs may be controllable by a simple ON/OFF switch, at the user's discretion. Here, however, the apparatus has an automatic control system for switching the LEDs on and off. The automatic control system is designed to ensure that UV light will be shone onto the keyboard for a sufficient length of time to provide effective sterilization. If desired, the system can be programmed to ensure that no UV light will be shone onto the keyboard whilst it is being used, as it may be preferred to avoid subjecting a user's hands to UV light.

The automatic control system here is triggered by detecting movement using an optical sensor. A beam of light emitted from a control LED mounted in the lamp console 10 is directed towards the keyboard and a sensor, also mounted in the console, is arranged to detect reflections of the control beam. Normally, when the keyboard is not in use, the reflected light picked up by the sensor will be unchanging. As soon as there is movement, e.g. from a user's hand, the pattern of reflected light will change and this will be detected by the sensor. Signals from the sensor are fed to a microprocessor, also mounted within the lamp console 10.

The microprocessor is programmed to switch on the UV LEDs after the keyboard has been used by a user and to switch them off again after a suitable length of time. It can also be programmed to ensure that the UV LEDs are switched off whilst the keyboard is actually in use. The length of time for which the UV LEDs remain on will be governed by their effective germicidal power and this will depend on various factors such as their intensity and spacing.

The control LED in the apparatus here is arranged to emit a beam of visible light for the movement detection system. It would instead be possible to use other forms of light such as infra red, or possibly even UV from the UV LEDs. Equally, it would be possible to use other sensing systems such as thermal, touch or proximity detectors.

Using visible light means that the sensor will of course be sensitive to ambient light from the surroundings, as well as to the beam of light from the control LED. In order to avoid spurious signals from the sensor, the control beam is arranged to be treated using a spread spectrum technique. This is controlled by the microprocessor.

Interference can come from many types of external light sources, including incandescent lights, fluorescent lights both conventional and with an electronic ballast, computer screens and even other optical sterilization apparatus. A conventional system would typically repeat sampling of the reflected control beam many times at fixed intervals and average the results.

Interfering signals at frequencies distant from the sampling frequency can be effectively discriminated against using high and low pass filters. However, conventional systems have little ability to discriminate against frequencies that are close to the sampling frequency. These therefore pass unattenuated through the high and low pass filters and add to the signal. In particular, signals from an adjacent similar unit will generate signals at a similar frequency, which will drift in and out of synchronism and may cause false detections.

The apparatus here uses random intervals between samples to avoid this problem. In one version, a random number generator determines the time between samples, with a minimum value determined by the settling time of the sensing system. Any signal that is not synchronised to the random samples will average down when samples are averaged. The length of the random sequence determines the probability of interference from an adjacent similar unit.

Another version uses random phase of sampling to achieve similar effects. The sampling pulse occurs at a random time within a fixed sample period. Thus the system waits for a random interval less than the pulse repetition time, samples and then waits for the remainder of the sample period. This simplifies the design of the digital filters in the system and ensures a more consistent response time.

The system of detecting the presence of a hand by variation in the reflected light does so by maintaining a short-term moving average of the sensor signals and a long-term moving average. The ratio of the two averages is used for the detection. Due to the movement of the user's hand, the short-term average will be different from the long-term average. A sufficient difference is used as the trigger. This system will compensate for any static changes in the keyboard andlor mouse environment.

A diagram of a suitable control circuit for the apparatus of Figures I and 2 is seen in Figure 3 Reference numeral 15 indicates the microprocessor that controls the operation. Reference numeral 16 indicates the array of UV LEDs that are mounted in the lamp console 10. In this case, there are five UV LEDs. The other two LEDs in the array emit bright visible light.

UV light can be harmful to the eye and, being invisible, it is not always possible to tell when it is incident upon the eye. Also, the eye will not normally react to UV light in the same way as it does with visible light: in particular, the iris will not automatically contract. If UV light is incident upon the eye in dark conditions, therefore, there will be a heightened risk from exposure, because the iris will be dilated. The siting of the two bright light LEDs amongst the array of UV LEDs helps to reduce this risk by causing a natural contraction of the iris. The effect of this will be to reduce the amount of UV light that is able to pass into the eye and hence reduce the level of possible damage to the retina.

The movement detection system uses a visible light LED 17 for the control beam and a sensor 18. Signals from the sensor 18 are filtered by a high pass filter 19 and low pass filter 20.

The apparatus described above is designed for use in particular with computer devices such as keyboards and mice. It will be understood, however, that the apparatus may be adapted for use with all manner of other devices and in all sorts of other situations. For example, the apparatus can be used with other data input devices such as credit/debit card readers, cash machines, electronic passport desks, public telephones, entryphones and so on. In these applications, the apparatus may be adapted to be mounted on or adjacent the device, rather than be free standing. The apparatus could be designed as an extra unit to be retro-fitted to an existing device or as an integral part of a new device. The apparatus may also be adapted to provide germicidal control in other applications not necessarily involving data input, for example in public facilities such as washrooms and lavatories, on public transport, in food preparation areas and so on.

Claims (14)

1. Claims 1. Sterilisation apparatus comprising means for directing a beam of germicidal energy at a target area, means for detecting changes of status in the target area, and means for switching the beam on and off in response to signals from the detecting means.
2. 2. Apparatus as claimed in claim 1 wherein the switching means includes a time delay mechanism to allow the beam to remain switched on for an interval of time before switching off.
3. 3. Apparatus as claimed in claim I or claim 2 wherein the switching means is arranged to switch off the beam whilst signals from the detecting means indicate ongoing changes of status in the target area.
4. 4. Apparatus as claimed in claim 3 wherein the switching means is arranged to switch the beam on for a predetermined time when signals from the detecting means indicate that changes of status in the target area have ceased.
5. 5. Apparatus as claimed in any preceding claim wherein the detecting means incorporates a random interval or phase sampling technique to eliminate spurious detections.
6. 6. Apparatus as claimed in any preceding claim wherein the detecting means detects changes of status by monitoring movement in the target area.
7. 7. Apparatus as claimed in claim 6 wherein the detecting means is an optical system using a control beam and a sensor.
8. 8. Apparatus as claimed in claim 7 wherein the control beam comprises visible light.
9. 9. Apparatus as claimed in any preceeding claim wherein the beam of germicidal energy comprises ultraviolet (UV) light.
10. 10. Apparatus as claimed in claim 9 wherein the UV light is produced from an array of light emitting diodes (LEDs).
11. 11. Apparatus as claimed in claim 9 or claim 10 and further comprising means for emitting bright light alongside said IJV light for provoking a reflex closing of the iris of an eye when the light is incident thereon,
12. 12. Apparatus as claimed in any preceeding claim wherein the apparatus is in the form of a free standing unit.
13. 13. Apparatus as claimed in any preceeding claim wherein the apparatus is connectable to a power source using a USB connection.
14. 14. Sterilisation apparatus substantially as herein described with reference to the accompanying drawings.