GB2300253A - Sunbeds - Google Patents

Abstract

A sunbed comprises a multiplicity of ultra-violet emitting tubes (9) each of which is located in a respective enclosure (10) defined between the front sheet (7) of the sunbed and a reflector (8). Fans (12) are provided for blowing cooling air through apertures or nozzles in the reflector into the enclosures (10) to cool the tubes. The temperature of the tubes is monitored and the rate of flow of air is adjusted to maintain the tubes at optimum operating temperature. The optimum operating temperature may vary with the life of the tube so that the tubes are run hotter as they age in order to maintain a desired level of UV output. Preferably, additional sensors are provided to shut down the sunbed if levels of UV-C output rise above a pre-determined level or if the temperature of the sunbed rises above a pre-determined level. Preferably, a key switch control safety timer is provided for preventing re-setting of the standard timer immediately after one period of use.

Description

SUNBEDS This invention relates to a sunbed, that is to say a device comprising a multiplicity of tubes each for emitting ultraviolet radiation to effect tanning of a person located adjacent the device. The sunbed may be embodied as a couch upon which the person using the sunbed lies, as a combined couch and cover in which both the couch and cover incorporate UV emitting tubes, or as a free standing unit which may be used above or to the side of a user to effect tanning of one side only of the user.

Sunbeds are well known and are used extensively for both cosmetic and therapeutic purposes. Typically, a sunbed comprises a rigid supporting structure, a reflector positioned on the supporting structure, a multiplicity of UV emitting fluorescent tubes and a clear UV transmissive cover overlying the tubes. The cover serves to prevent direct contact with the tubes and, in the case when the sunbed is embodied as a couch, serves to provide a supporting surface upon which the user lies.

The existing sunbeds suffer from a number of significant disadvantages. Firstly, existing sunbeds inadequately control the operating temperature of the fluorescent tubes. Any particular fluorescent tube has. at any particular point during its life, an optimum operating temperature. If the tube is operated at below its optimum temperature the level of UV emission will be reduced and will be inadequate to effect the desired irradiation of the user. If the tube is run at a temperature above its optimum temperature an excessively high level of UV radiation may be emitted and, in the case of extreme over temperature operation harmful UV-C radiation may be emitted.

Running tubes above the optimum temperature also tends to reduce the useful life of the tube. Since there is a general tendency for the UV output of tubes to decrease with increasing age, and since there is a tendency for the level of UV emission to increase with temperature, it can be desirable to increase the operating temperature of the tube as it becomes older in order to maintain a desired level of UV output.

Secondly, the controls of existing sunbeds do not adequately guard against an individual receiving an excessive amount of UV radiation as a result of component failure or deliberate abuse of the controls.

The present invention provides a sunbed with substantially improved controls to optimise the effectiveness of the sunbed and the life expectancy of the tubes, and to prevent an individual from receiving an excessive amount of UV radiation as a result of component failure or deliberate misuse of the sunbed controls.

The invention will be better understood for the following description of a preferred embodiment thereof, given by way of example only, reference being had to the accompanying drawings wherein: Figure 1 illustrates schematically an embodiment of the present invention embodied as a sunbed of the type comprising a couch and a cover each incorporating UV emitting tubes; Figure 2 is a perspective view from above of the cover portion of the sunbed of Figure 1; Figure 3 is a schematic perspective view of the reflector incorporated within the couch and the cover of the embodiment of Figure 1; and Figure 4 is a schematic cross section on the line IV-IV of Figure 2.

The sunbed illustrated in the drawings comprises a couch portion 1 supported on conventional legs 2, 3 and a cover portion 4 supported on the couch portion 1 by means of appropriate arms 5 to permit articulation of the cover portion relative to the couch portion. This general form of structure of sunbed is well known to those skilled in the art and the exact nature of the interconnection between the cover portion and the couch portion. and the means of controlling the position of the cover portion relative to the couch portion is not critical to the present invention.

The preferred embodiment of the present invention incorporates various arrangements to optimise the operation of the sunbed, to ensure the maximum effective life of the tubes, and to prevent those using the sunbed receiving excessive levels of UV radiation. To achieve these objectives the sunbed incorporates a novel arrangement for circulating cooling air around the tubes and incorporates various sensors and monitors enabling a range of characteristics of operation of the bed to be monitored.

Electronic control apparatus is provided for co-ordinating the operation of the bed and ensuring appropriate control in light of the output from the sensors and monitors.

Referring to Figure 4 there is shown schematically a cross-section of the cover portion 4. A cross section of the couch portion 1 would be a substantially inverted or mirror image version of Figure 4. In general, the couch portion would be constructed somewhat more robustly than the cover portion in light of the fact that the couch portion must support the weight of a user. However, the actual mechanical construction of both the cover portion and the couch portion is not critical to the present invention and details of such mechanical construction will be well known to those skilled in the art.

Referring now to Figure 4, the cover portion 4 comprises a casing 6, a UV transparent front sheet 7, a generally corrugated reflector 8 and a multiplicity of UV emitting fluorescent tubes 9. It will be appreciated that the exact number of fluorescent tubes will be determined by the designer in light of the required intensity of UV radiation and the output of the particular tubes used. The reflector 8 may be unitary or may be formed as a number of separate components interconnected to provide the overall reflector configuration illustrated in the drawing.

The reflector 8 engages, at the crest between each adjacent pair of tubes, the front sheet 7. In the case of the couch portion, the front sheet 7 is mechanically supported on the reflector, the crests of the reflector providing support areas for the front sheet which extend substantially the full length of the sunbed. In the case of the cover portion, since the front sheet is unlikely to be exposed to substantial mechanical loading the front sheet need not be mechanically supported by the reflector, although in the interest of general robustness and with a view to reducing the total number of separate components required the construction of the reflector, reflector supports (not shown) and front sheet for the cover portion may be identical to that of the couch portion.

Because the front sheet 7 touches the crests of the reflector 8 at each crest, each tube 9 is located in a separate enclosure 10, each enclosure being in the form of a generally triangular cross-section cylinder two sides of which are formed by the reflector 8 and the third side of which is formed by a portion of the inner surface of the front sheet 7. Within the casing 6 to the rear of the reflector 8 (i.e. on the side thereof remote from the front sheet 7) there is defined one or more chambers 11. A single chamber 11 may extend the full length of the sunbed or. if desired, a number of separate chambers dividing the total area of the cover portion longitudinally and/or transversely may be provided. Each chamber 11 has associated therewith at least one fan 12 which is electrically operated to force ambient air from the exterior of the covering 6 into its associated chamber 11.In the preferred embodiment of the invention in which a single chamber 11 is defined within the casing 6, two fans 12 (Figure 2) are provided to supply air to the chamber 11.

Referring now to Figure 3 it will be seen that the reflector 8 is formed with a multiplicity of apertures or, preferably, nozzles to permit air to flow from the chamber 11 into the individual enclosures 10 defined between the reflector and the front sheet 7. The nozzles are located adjacent the crests 13 of the reflector which contact the front sheet 7. The apertures are preferably in the form of nozzles so that air flowing from the chamber 11 through the nozzles is specifically directed towards the interior surface of the front sheet 7. This arrangement is particularly desirable since it provides for cooling of the front sheet and avoids direct impingement of cold air onto the surfaces of the tubes 9.When considering any particular enclosure 10, the nozzles located adjacent the front sheet 7 at one side of the enclosure are offset from the nozzles at the opposite side of the enclosure.

Expressed another way, when the nozzles adjacent any one crest are considered, the nozzles on alternate sides of the crest are offset relative to each other. Air entering the enclosures 10 through the nozzles 14 flows axially along the enclosures 10 to exit from the cover portion or couch portion as the case may be through appropriate exit openings 15 located adjacent the ends of the bed. Thus, in use, air is drawn by the fans 12 into the chamber 11, flows through the apertures 14, axially along the enclosures 10, and outwardly through the exits 15. If desired, an appropriate dust filter may be incorporated immediately upstream or downstream of the fans 12.

The effect of the positioning of the nozzles as described above is that air flowing along the enclosure 10 will do so in a "turbine" manner - that is to say the air will be caused to rotate around the tube in opposite directions as it moves along the chambers 10 towards the exits 15. This flow arrangement has been found to be particularly satisfactory for use in controlling the temperature of the tubes 9.

With a view to controlling the operation of the sunbed to provide for optimum operation of the tubes a number of sensors are provided on or near the tubes to monitor the temperature of the tubes. The output of such sensors is applied to suitable electronic control circuitry to control operation of the fans 12 to maintain optimum temperature conditions for the tubes. It will be appreciated that a large number of factors will affect the air flow rate required to maintain optimum temperature for the tubes. Such factors as ambient air temperature, the length of time that the sunbed has been in use, the size of the user, etc. will affect the air flow rate necessary to maintain optimum operating conditions.By sensing the temperature of the tubes, and by using the output of such sensors to control the air flow rate optimum tube temperate can be maintained not withstanding variations in the conditions noted above.

The preferred embodiment of the invention also includes sensors monitoring the UV output of the tubes.

Preferably, this information is co-ordinated with information as to the expected characteristics of such tubes and information derived from the temperature sensors to vary the optimum temperature which is maintained by the control system to ensure that, so far as possible, a desired standard level of UV emission is maintained throughout the life of the tubes. This will ensure that the amount of UV radiation received by a user in a given period of exposure (e.g. 30 minutes) will be constant regardless of the age of the tubes used. Sensors are also preferably included to be specifically responsive to UV-C radiation and to shut down the bed and inhibit its future use if levels of UV-C radiation rise above predetermined permissible limits.

With a view to guarding against excessive temperature conditions which might arise as a result of failure of the tube temperature sensors or malfunction of the control system, additional sensors responsive to the temperature at the enclosure outlets and the air flow rate through the fans 12 are preferably provided.

Such sensors provide redundancy in respect of the tube temperature sensors, and can additionally be used to shut the system down immediately in the event of, for example, fan failure or blockage of the inlet or outlet openings.

Preferably, in addition to the sensors which operate via the control system separate electromechanical switches are provided which completely isolate the sunbed from mains electrical power in the event that the temperature of the system rises to an excessive level.

In a particularly preferred embodiment of the invention means are provided for inhibiting starting of the tubes if the temperature of the system is below a predetermined level. This arrangement ensures that the tubes are not used to "warm up" the entire system.

Typically, in prior art arrangements the tubes had to be left switched on for, perhaps, 10 minutes in order to warm the entire system up before the UV output of the tubes rose to an acceptable level. In the preferred embodiment of the invention auxiliary heating means are provided for heating the system prior to switching on of the tubes. By this means, the device can be heated up relatively rapidly to operating temperature and, in addition, the effective life of the tubes (i.e. the number of sessions which a tube will provide) is substantially increased because the tubes are not switched on other than when actually in use or for a very short period before use in order to raise the tubes themselves to the required operating temperature.

In a particularly preferred embodiment of the invention the cooling fans 1 2 continue to operate after the tubes have been switched off at maximum available flow rate in order to cool the tubes as quickly as possible at the end of each session. This again increases the effective life expectancy of the tubes.

Preferably, the front sheet 7 incorporates or has associated therewith one or more wire mesh screens with a view to increasing the mechanical strength and breakage resistance of the front sheet and with a view to providing an earthed conductor network to ensure effective dissipation of electrostatic charge which would otherwise tend to accumulate on the front sheet.

Preferably, the control device incorporates a count-down timer which is preset to a maximum period of exposure and which counts down from that period as the bed is used. In a particularly preferred embodiment of the invention, in addition to the standard timer there is incorporated an automatic safety timer which is preset to a suitable time (longer than the maximum available from the standard timer) which is considered to be the maximum possible safe period of exposure for the particular level of output of the sunbed. This timer cannot be reset using the ordinary start/stop controls of the bed. As a result, if having completed a particular preset period of exposure a user immediately resets the standard timer with a view to gaining further exposure, the automatic safety timer will operate after a few minutes to shut down the entire system.

Preferably, the automatic safety timer can only be reset by use of a key switch.

Preferably, the control panel incorporates a number of indicators to confirm normal operation of the sunbed and to provide alarm indications in the event of failures detected by one or more of the sunbed sensors.

Claims (10)

CLAIMS:

1. A sunbed comprising a multiplicity of ultra-violet emitting tubes; means for passing cooling air over the exterior surface of the tubes to cool the tubes; means for sensing the temperature of the tubes; and means responsive to the sensed temperature of the tubes for controlling the rate of flow of cooling air in order to maintain the temperature of the tubes at a desired value.

2. A sunbed according to Claim 1 comprising means for sensing the ultraviolet output of the tubes; and means responsive to the output of the ultra-violet sensor for selecting the desired value of the temperature.

3. A sunbed according to Claim 1 or Claim 2 comprising means for detecting the emission of UV-C radiation above a pre-determined value; and means responsive to the UV-C detector for shutting down the sunbed.

4. A sunbed according to any preceding claim comprising one or more safety sensors for detecting, independently of the temperature sensors, if the temperature of the sunbed rises above a pre-detennined level or if the flow of cooling air falls below a pre-determined level, and for shutting the sunbed down in response to such detected events.

5. A sunbed according to any preceding claim comprising a warm-up heater for warming the sunbed prior to switching on the ultra-violet emitting tubes.

6. A sunbed according to any preceding claim comprising an overrun control for controlling the means for passing cooling air over the exterior surface of the tubes so that cooling air continues to pass over the exterior surface of the tubes after the tubes have been switched off.

7. A sunbed according to any preceding claim wherein the sunbed incorporates a standard timer and a safety timer, the standard timer being settable by a user of the sunbed to provide a period of use and the safety timer being effective to inhibit operation of the ultra-violet emitting tubes if the standard timer is re-set at the end of one period of use to provide a second period of use immediately thereafter, the safety timer preferably being re-settable by a key switch.

8. A sunbed according to any preceding claim wherein each ultra-violet emitting tube is located in a respective enclosure defined between a front sheet of the sunbed and a reflector and wherein the means for passing cooling air over the exterior surface of the tubes comprises means for forcing air into said enclosures through apertures or nozzles provided in the reflector along the length of the tubes.

9. A sunbed according to Claim 8 wherein the apertures or nozzles direct cooling air at the front sheet and, for any one enclosure, are offset from each other along opposite sides of the enclosures so that air rotates around the tube in opposite directions as it moves along the length of the tubes.

10. A sunbed according to any preceding claim wherein the sunbed has a front sheet which incorporates a wire mesh which is earthed to prevent build up of static electricity.