GB2149490A

GB2149490A - U.V. Irradiation apparatus

Info

Publication number: GB2149490A
Application number: GB08428107A
Authority: GB
Inventors: Folkert Johannes Emmelkamp; Theodorus Franciscus Lamboo
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1983-11-10
Filing date: 1984-11-07
Publication date: 1985-06-12
Also published as: NL8303856A; DE3438519C2; BE901019A; DE3438519A1; FR2559672A1; FR2559672B1; GB2149490B; GB8428107D0

Abstract

An ultraviolet irradiation apparatus such as a sun bed or sun canopy emitting radiation having a wavelength greater than 315 nm (UV-A radiation) comprises a housing (1) enclosing an array of mutually parallel extending UV- A irradiation lamps (3a... 3j). The lamps have a reflecting layer (4a) over part of their internal curved surface. Additionally, each lamp has a window (5a, 5b, 5c etc.) through which the UV radiation can be emitted. At least the outer lamps in the array are oriented about their own axes such that their windows are inclined towards the centre of the array. Consequently a body lying on the apparatus is irradiated from the sides as well as directly from below without using specially shaped external reflectors in the housing. <IMAGE>

Description

SPECIFICATION Irradiation device The invention relates to an irradiation device for emitting ultraviolet radiation having at least a wavelength larger than 315 nm (UV-A radiation), which device comprises a plurality of mutually parallel substantially co-planartubular low-pressure mercury vapour discharge lamps arranged such that a plane of symmetry extends parallel to the axes of the lamps and at right angles to the plane in which lie the axes of at least the two lamps nearest said plane of symmetry, said lamps each comprising a tubular discharge vessel whose inner wall over part of its circumference is provided with a layer which reflects ultraviolet radiation, each of said lamps further comprising a window permitting the emanation of ultraviolet radiation.

A device having the features mentioned in the previous paragraph is known from Dutch Patent Application 7710575 laid open to public inspection.

This irradiation device can be used for photochemical or photobiological purposes, for example as a sun bed or sun canopy or a wallshaped sun panel, as a face irradiator and the like for direct pigmentation of the skin (tanning without formation of erythema) or in the phototherapy of skin diseases. With this device the body can be subjected for some significant time to long-wave ultraviolet radiation (UV-A radiation).

In the aforementioned Dutch Patent Application laid open to public inspection, an irradiation chamber for phototherapy is described, in which an irradiation space is surrounded at least in part by a wall in which are present a large number of vertically arranged tubular low-pressure mercury vapour discharge lamps emitting UV-A radiation.

The wall is composed of a number of flat parts, which enclose an obtuse angle with each other. The free area within the chamber is constituted, for example, by a regular hexagon. It is then possible to subject simultaneously the sides and the front and the back of the body to radiation. Unfortunately, however, such a device is voluminous and has a relatively complicated construction. This is disadvantageous especially for use in comparatively small rooms.

According to the invention, an irradiation device having the features mentioned in the opening paragraph is characterised in that the windows of at least the lamps located farthest from the plane of symmetry are oriented obliquely towards this plane of symmetry.

The term "oblique" isto be understood herein to mean that the relevant lamp is inclined such that the main direction of the radiation emanating from the window subtends an acute angle at the plane of symmetry. In a practical embodiment, this angle is about 350 for a lamp located farthest from the plane of symmetry.

An irradiation device in accordance with the invention may have relatively small dimensions.

The device has the further advantage that a person can be irradiated simultaneously from several sides whilst avoiding a complicated construction for the housing in which the lamps are arranged. Also, the use of specially shaped external reflectors in the housing, as present in certain known devices especially behind the outermost lamps, is avoided.

In an irradiation device in accordance with the invention, the axes of the lamps are preferably located in a flat plane. For such an arrangement of the lamps, the housing can be manufactured in a simple manner.

In a preferred embodiment of a device in accordance with the invention, at least four lamps are present in the housing and the oblique orientation of the window of a lamp with respect to the plane of symmetry is less strongly pronounced as the distance of this lamp from this plane of symmetry decreases. In this manner, a homogeneous radiation intensity is obtained on the body being irradiated. This embodiment further has the advantage that especially with sun canopies or face irradiators the use of a special parabolic reflector behind the sources of radiation is not necessary for obtaining concentrated beam.

Therefore the housing need not be adapted specially for this purpose.

In a particular embodiment of the device according to the invention, the mutual spacing of the lamps remote from the plane of symmetry is smaller than the mutual spacing of the lamps located near the plane of symmetry. The body parts located on the sides can then also be subjected to an intense radiation.

An embodiment of the invention will now be described, by way of example, with reference to the drawing. In the drawing: Figure 1 shows diagrammatically in perspective view an embodiment of an irradiation device in accordance with the invention; and Figure 2 is a cross-section of the irradiation device shown in Figure 1 taken on the plane Il-Il.

The irradiation device in the form of a couch-type sun panel (sun bed) for emitting ultraviolet radiation shown in Figure 1 comprises a rectangular housing 1 having walls arranged at right angles to each other. The upper side of the housing is provided with a cover plate 2, which is transparent to ultraviolet radiation having a wavelength larger than 315 nm (UV-A radiation). This radiatiion is produced by ten mutually parallel tubular lowpressure mercury vapour discharge lamps located in a single flat plane. These lamps are designated by reference numeral 3.Each of the lamps 3 comprises a tubular discharge vessel the inner wall of which is provided with a reflecting layer (designated, by way of example, for the lamp 3a by reference numeral 4a), which extends only over a part of the circumference, for example an arc of 1800 to 2400 (see Figure 2). There is applied over the remaining part of the circumference and over the said reflecting layer a luminescent layer (not shown in the drawing) which converts the Hg-resonance radiation of 254 nm produced in the mercury discharge into ultraviolet radiation having a wavelength larger than 315 nm. Each of the lamps 3 also has a window (for example 5a), i.e. that part of the circumference which is free from the said reflecting layer, permitting the emanation of ultraviolet radiation.The ultraviolet radiation emanates from the housing via the plate 2.

The tubular discharge lamps 3 are located on both sides of a plane of symmetry 6 extending in the direction of the axes of these lamps and at right angles to the plane in which the lamps lie (see Figure 2). The window (5a, 5b, 5c) of the lamps is obliquely oriented towards the plane of symmetry, as shown in Figure 2. The lamps are thus slightly rotated about their longitudinal axes. The lamps located farthest from the plane of symmetry (3a and 3j) have a window which is oriented more obliquely than that of the lamps located closerto the plane of symmetry, such as 3b and 3c.

The oblique orientation of a window can be characterised by the dotted lines 7a, 7b, 7c representing the main direction of the radiation emitted by a lamp (3a, 3b etc.). For illustration, a line (7a) is shown which is at an angle of about 350 to the plane of symmetry 6. The other such lines enclose a more acute angle as the distance from the plane of symmetry 6 is smaller.

As appears from Figure 2, also the body parts located at the sides of a person lying on his stomach or on his back on the cover plate 2 can be irradiated.

In the present embodiment the irradiation device serves as a sun bed. The housing 1 may alternatively serve as a sun canopy, however. In an alternative embodiment, the housing has a slightly curved form. The irradiation lamps are arranged with respect to each other so that the longitudinal axes are then located in a slightly curved arrangement. In another embodiment, no glass plate is present on the radiation-emanating side of the housing.

In a practical embodiment of an irradiation device as shown in Figure 1 the housing has a length of about 2 m, a heightofabout 15cm and a width of about 60 cm. The length of the tubular discharge lamps is about 1.80 m (power about 100W, outer diameter about 38 mm). The distance between the axes of neighbouring lamps is approximately 10 cm.

In an alternative embodiment, however, the distance between the outermost lamps 3a and 3b (and 3i and 3j) is 8 cm whereas the distance between neighbouring lamps 3b and 3c is greater, for example 10 cm. A reflecting layer consisting of aluminium oxide is present on the inner wall of the discharge vessel of these lamps over about 1800 of the tube circumference. A radiation-emanating window of 1800 is then left, which is free from this reflecting layer. Furthermore, there is applied over the whole circumference a luminescent layer which converts the resonance radiation of mercury into UV-A radiation. Consequently, the luminescent layer is present both at the area of the window and on the reflecting layer. The luminescent layer contains strontium tetraborate activated by bivalent europium. The radiation emitted by this luminescent material has a wavelength of about 370 nm.

Claims

1. An irradiation device for emitting ultraviolet radiation having at least a wavelength larger than 315 nm (UV-A radiation), which device comprises a plurality of mutually parallel substantially co-planar tubular low-pressure mercury vapour discharge lamps arranged such that a plane of symmetry extends parallel to the axes of the lamps and at right angles to the plane in which lie the axes of at least the two lamps nearest said plane of symmetry, said lamps each comprising a tubular discharge vessel whose inner wall over part of its circumference is provided with a layer which reflects ultraviolet radiation, each of said lamps further comprising a window permitting the emanation of ultraviolet radiation, characterised in that said windows of at least the lamps located farthest from the plane of symmetry are oriented obliquely towards said plane of symmetry.

2. An irradiation device as claimed in Claim 1, comprising at least four lamps, characterised in that, as the distance of a lamp from the plane of symmetry dereases, the oblique orientation of its window with respectto said plane of symmetry is less strongly pronounced.

3. An irradiation device as claimed in Claim 1 or 2, characterised in that the axes of the lamps are located in a flat plane.

4. An irradiation device as claimed in Claim 1, 2 or 3, characterised in that the mutual spacing of lamps located remote from the plane of symmetry is smaller than the mutual spacing of lamps located nearer the plane of symmetry.

S. An irradiation device for emitting ultraviolet radiation having at least a wavelength larger than 315 nm (UV-A radiation) substantially as herein described with reference to Figures 1 and 2 of the accompanying drawing.