GB2077897A - Sun bed construction - Google Patents

Abstract

A sun bed comprises a support structure 1 with a translucent panel 2 on which a user may rest, a bank of UV fluorescent tubes 3 below the panel in channel sectioned reflectors 4, and a housing 5 containing a bank of starter coils 6, and a fan 7 which passes cooling air over the coils 6. The reflectors 4 are each of channel sections and each encompass a pair of parallel fluorescent tubes 3, and have a central longitudinally extending ridge between the tubes to direct divergent rays from the tubes into the main beam of the reflector. <IMAGE>

Description

SPECIFICATION Improvements in and relating to sun beds This invention relates to improvements in sunbeds for treatment of the skin with artificially produced radiations for therapeutic and cosmetic purposes. Beds of this kind usually comprise a generally horizontal support in the general form of a bed or couch with fluorescent tubes which emit energy in the ultra violet part of the spectrum disposed in a bank below and/or above the bed.

Such tubes require a starter coil, in order to strike an arc through the gas with which they are filled, and the spectral characteristics of which determine the wave length components of the light emitted from the tube. The starter coils of fluorescent tubes are in electrical terms choke coils and in, for example, lamp fittings, are customarily housed either at the end or immediately adjacent the tube terminals. In a bank of tubes this can require a considerable amount of additional volume to be used, with consequent increase in weight and material requirements for the bed structure. The solution has been to house the coils, or a sipgle coil for all tubes (which risks failure of all the tubes if the one coil fails) beneath the bed.However, it is found in practice that the coils generate heat of an intensity which causes discomfort to the user of the bed, negating the usual design of the fluorescent tubes which are designed to avoid heating the user of the bed.

An object of the invention is to provide an improved sun-bed wherein the problem of discomfort caused to the user is mitigated substantially or completely.

In accordance with the invention a sun-bed comprises a structure for supporting a person lying thereon, with a translucent platform for directly supporting the persons weight and allowing ultra violet light from a bank of fluorescent tubes below the platform to reach the person; the starter coil or coils for the tubes being located in a housing below the bank of tubes, the said housing being provided with fan means for blowing air over the coils for preventing overheating of the same.

From another aspect, the invention concerns an improved reflector for reflecting the radiation emitted by the fluorescent tubes of a sun-bed comprising a channel sectioned member having a reflective concave surface, the channel section accommodating two or more emitting tubes, characterised by a ridge extending longitudinally of the reflector along the base of the channel section and convexly protruding into the channel between the location of each pair of adjacent tubes.

This ridge increases the proportion of light emitted by the tube which is reflected directly towards a person on the bed instead of being lost by reflection out of the main beam of the reflector, thereby increasing the efficiency of the emitter.

Where a reflector accommodates two parallel side by side fluorescent emitting tubes, a single median longitudinal ridge is provided; where three tubes are accommodated, two parallel ridges will be provided one between each pair of tubes.

Where the reflector is made from bright sheet metal, the ridge may be swaged or formed by bending in the same process as the general channel section configuration is formed. The or each channel may be from 1 to 2 cm wide, and 2 to 5 mm deep and be of generally rounded or generally triangular cross-section.

The fan used for blowing air over the coil or bank of coils housed below the bed may be a cylindrical paddle fan which blows air in a stream at right angles to the axis of rotation of the fan, along the length of the fan, providing a broad shallow airstream.

In a preferred embodiment, which is described by way of example, as shown in Fig. 1 a sun-bed for treatment of the skin with artificially produced radiations comprises a support structure 1 with a translucent panel 2 whereon a user may rest, and a bank of fluorescent tubes 3 disposed below the panel and arranged in pairs within channel sectioned reflectors 4. Below the bank of tubes is disposed a housing 5, arranged inset below the support structure to be inconspicuous and this housing 5 contains a bank of starter choke aids 6.

In the preferred embodiment there is a single coil for each tube 3, however a single coil may be used for all the tubes, or the tubes grouped into groups operated from a coil for each group. A separate coil for each tube is preferred, since failure of a coil will only prevent the operation of one of the tubes.

In the housing is mounted a cylindrical paddlefan 7 which draws air from an inlet slot in the housing 5 and blows air in a quasi-laminar flow over a broad front over the bank of choke coils 6.

This flow of air serves to provide a steady heatsink passing over the coils, thereby preventing accumulation of heat in the tubes thus avoiding the temperature of the tubes rising to a level where discomfort would be caused to a person lying on the bed.

The tubes 3 are designed to emit radiation including the longer-wave ultra violet radiations, in the wavelength region from 300 to 400 nm.

These softer wavelengths stimulate production of vitamins, and formation of pigment as a barrier to the "harder" radiations from 200 to 300 nm which cause skin burns and promote skin cancers.

Exposure to the "softer" radiations with an energy distribution a proportion of 100 to 200/1 of radiation from 315-400 nm/radiation shorter than 315 nm therefore promotes tanning and health, the tan enabling the patient to better withstand natural solar radiations which in the tropical and sub-tropical and mediterranean zones contain much higher proportions of "hard" ultra violet radiation below 280 nm wavelength than in temperate and sub-arctic regions.

Fig. 2 is a cross-sectional view of one of the reflectors 4. These each comprise a sheet metal member formed into a channel section, and either having a bright metal surface, or a special reflective coating, at least on the concave face of the reflector 4. Each reflector is designed to accommodate two tubes 3, and in accordance with the invention a longitudinally extending ridge 8 extends along the median line of the base of the channel section, between the two tubes.

This ridge has the effect of reflecting a proportion of light emitted from each of the tubes, into the zone of the central axis of the beam emergent from the reflector which would, if the ridge had not been present. This is demonstrated by the ray paths traced in Fig. 2. Ray "B" is emergent from one side of the tube 3, and the ray reflected from the ridge 8 B' is close to the optical axis of the reflector 4. The broken line BB shows the path of an equivalent ray reflected from a flat reflector without a central ridge. This ray is strongly divergent from the axis of the reflector, and escapes from the main beam of the reflector.

Ray A, from the inner edge of the tube 3 is reflected by the ridge on path A, whilst the equivalent path of a ray reflected from a flat reflector is shown at AA. The ridge thus has the effect of tightening the beam from the reflector and reducing the proportion of emitted radiation which "leaks" from the sides of the beam. The efficiency of the lamp is thus increased, and lower or fewer emitters tubes may be used if desired to obtain a desired strength of radiation.

The ridge is formed in the same process as the channel section. The ridge may be from 1 to 2 cm broad, and 2 to 5 mm deep, and of rounded or triangular cross-section; preferably 15 cm wide and 3 mm deep.

The reflector may be used for purposes other than for a sun-bed; e.g. in any installation of two or more parallel tubes for lighting or heating.

The invention in both its aspects may be adapted to an over-head emitter.

Claims (8)

1. A sun bed comprising a structure for lying thereon, a transluant platform for directly supporting the person's weight and allowing ultraviolet radiation from a bank of fluorescent tubes below the platform to reach the person, a starter coil or plurality of starter coils for the tubes being located in a housing below the bank of tubes, the said housing being provided with fan means for blowing air over the coils for preventing overheating of the coils.

2. A sun bed according to claim 1, wherein said fan means comprising a cylindrical paddle fan arranged to blow air in a stream at right angles to the axis of the fan along the length of the fan providing a broad shallow air stream impinging on the starter coil housing.

3. A sun bed according to claims 1 or 2 wherein the tubes produce radiation predominantly in the band from 300-400 nm, the energy spectral distributors being such that the 100 to 200 runs as much energy as emitted in the band 31 5-400 nm than at wavelengths shorter than 315 nm.

4. A sun bed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

5. A reflector for a group of two or more fluorescent tubes arranged side by side and parallel said reflector comprising a channel sectioned member having a reflective concave surface, a ridge being provided extending longitudinally of the reflector along the base of the channel section and convexly protruding into the channel between the location of each pair of adjacent tube.

6. A reflector according to claim 5 wherein the ridge is of curved cross section.

7. A reflector according to claim 5 or 6 which is made of sheet metal having a reflective coating or bright metal surface, the ridge being formed by folding or bending in the seam process as the channel section is formed.

8. A reflector substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.