THERAPEUTIC LAMP FOR BIOSTIMULATION WITH POLARIZED LIGHT

Abstract: A therapeutic lamp (1) for biostimulation with polarized light, which comprises a light source with a power substantially between 30W and 300W, a reflector (5) with a rotational paraboloid light reflecting surface arranged behind the light source so that the focal point substantially coincides with the point source, a polarizer (4) arranged in the path to generate polarized output light which has a cross-­ section of at least 100 cm². The lamp further comprises a first tube (3) with a first axis coinciding with axis of rotation of the paraboloid surface, the reflector (5) with the light source is fixed in the first tube (3) so that a sealed connection is provided therebetween, a second tube (2) with a second axis which closes an angle between 110° and 120° with the first axis, the tubes have substantially equal and circular cross-sections and are attached to each other to form an integral housing, both of the tubes are cut with a plane extending normal to a plane determined by the first and second axes, the cutting plane closes substantially the same angle with the first and second axis, whereby an opening with an elliptical contour line is defined, a light diverting means (4) preferably the polarizer closes the opening for the diverting light arriving from the first tube (3) to axial direction of the second tube (2), the means (4) comprises a closing plate (24) of a heat conducting material and has a heat dissipating increased rear surface (25), a light transparent plate (7) is arranged in frontal section of the second tube to close and seal the inner space thereof, and static heat dissipating means which contacts the reflector (5) for providing operational temperature for the light source.

Description: The invention relates to a therapeutic lamp for biostimulation with polarized light. The term "therapeutic" should be interpreted in broad sense which covers all applications of biostimulation for which polarized light can be used. DE-A-32 20 218 describes the general biostimulating effects of polarized light. The lamp described in the examples of that patent comprises a light source, e.g. a metal halogen bulb, which is substantially a point source, a reflector with a rotational paraboloid light reflecting surface defining a focal point arranged behind the light source so that the focal point substantially coincides with the point source to reflect forward the majority of light emitted by the source in a parallel path, a Brewster polarizer arranged in said path to generate polarized output light propagating in a predetermined direction to provide an output light bundle with parallel rays and with a circular cross-section, and a light filter plate being transparent for light of wave lengths exceeding 300 nm. Said light bundel has a diameter of about 50 mm and the lamp power is about 150 W. The lamp generates much heat which is transported away by means of a fan. In WO-A-84/03049, a further therapeutic lamp for biostimulation with polarized light is described, in which also a Brewster-type polarizer is used which is effective also in the infrared range of wavelengths. Owing to the utilization of the infrared spectral components of the bulb a substantial reduction of the required lamp power could be attained. The use of a Brewster-type polarizer requires that the passageway of the light beams be tilted in a predetermined angle, in which the direction of the output beams close an angle of 114° (twice the Brewster angle) with the main direction of the light source. This requirement substantially affects the form of such lamps. In the above referred type of the lamp a substantially cylindrical case was used which comprises a separate handle portion and an obliquely directed frontal portion. In the frontal portion specific filter elements and a glass plate were provided to prevent the surface of the polarizer from the dust present in the sucked-in air. The cooling of the case was provided by a fan and it was designed in such a way that the casing remained substantially open which could not safely prevent the sensitive light reflecting or transpassing surfaces from getting dusty with time. The cross-section of the output light of such a therapeutic lamp can not be increased without difficulties. If the cross-section is increased, the cooling used so far gets rapidly insufficient or if the airflow of the fan is increased, then the danger of dust formation on the optical surfaces also increases. With increased light cross-section the volume and weight of the lamp can be substantially higher which makes the holding and positioning of the lamp more difficult. The operation of the lamp requires the use of a separate power supply. The EP-A-0 148 144 describes a different kind of therapeutic lamp which is designed for providing larger light cross-sections. This lamp comprises a housing arranged in the lower part of the device which is similar to the widely used overhead projectors. The upper surface of the housing is made by a Fresnel lens. In the housing there is provided a metal halogen lamp with a higher power i.e. between about 200 to 800 W and the lamp is arranged in the focal line of the Fresnel lens. A parabolic reflector surface is provided below the lamp to reflect the backwardly radiated rays towards the lens. In the housing an intensive cooling is provided by means of a fan. The device comprises a Brewster polarizer arranged as a separate unit fixed to the upper rear edge of the box-like housing and extends obliquely in upward and forward direction. The weight and volume of such a lamp is high and the intensive cooling makes disturbing noise and heat. Owing to the open design the optical surfaces are exposed to dust and dirt. For several therapeutic applications it is sufficient if the cross-section of the polarized light bundle has a square dimension of about 100 to 300 cm². For such applications there is a need for a quietly operating therapeutic lamp which can be handled easily and in which the possibility of dust formation is highly reduced. An object of the invention is to provide a therapeutic lamp for generation of a polarized light bundle of a cross-section of at least 100 cm² with such properties, i.e. which has a static cooling, in which dust building is practically eliminated, which stands in a stable position and which enables an easy handling. A further object of the invention is to provide such a lamp with reduced manufacturing costs and without the need of a separate power supply and electronic unit. A further object is the need for extending the expected lifetime and for increasing the effectiveness of biostimulation. According to the invention a therapeutic lamp for biostimulation with polarized light is provided, comprising a light source with a power substantially between 30 W and 300 W and being substantially a point source, a reflector with a rotational paraboloid light reflecting surface defining a focal point and arranged behind the light source so that said focal point substantially coincides with said point source to reflect forward the majority of light emitted by said source in a parallel path, a Brewster polarizer arranged in said path to generate polarized output light propagating in a predetermined direction and having a cross-section of at least 100 cm², a light filter plate being transparent for wavelength components exceeding 400-450 nm, and an integral housing preferably made of a plastic material and formed of a first tube with a first axis and with a bottom end normal to said first axis and of a second tube with a second axis forming with said first axis an angle being twice the Brewster angle, i.e. about 114°, said tubes having substantially equal and circular cross-sections and being attached to each other, said reflector with said light source being fixed in said first tube so that a sealed connection is provided therebetween, said first and second tubes being cut along a plane extending normal to the plane containing said first and second axes so that said plane cuts substantially the whole cross-sections of both tubes, said cutting plane forming substantially the same angle with said first and second axis, whereby an opening with an elliptical contour line is defined, a light diverting means closing said opening for diverting light arriving from said said reflector in said first tube to the axial direction of said second tube, said light diverting means comprising said polarizer and comprising a closing plate of a heat conducting material and having a heat dissipating increased rear surface, said light filter plate being arranged in the frontal section of said second tube to close the inner space thereof, a toroid transformer for supplying said light source with a small voltage being arranged in the first tube below said paraboloid surface, static heat dissipating means contacting said reflector for providing operational temperature for said light source, said heat dissipating means comprising a metal closure plate attached to said bottom end of said first tube to close the hollow cavity thereof, said closure plate being provided with cooling grooves, said housing further comprising a pair of spaced legs extending from the frontal portion of said second tube downwardly substantially parallel to said first axis, said legs being extended by horizontal rods, said first tube comprising a hollow rectangular portion extending along the frontal zone thereof and ending in said second tube, a horizontal projection being extending out of the bottom of said rectangular portion to receive ends of said horizontal rods, and electronic circuits for operating the light source being arranged in the hollow space of said rectangular portion of the first tube. This basic design is useful, since the effective utilization of the lamp output enables the use of a smaller lamp power, and the large diameter of the tubes provide a static cooling in combination with the large reflector surface and large surface of the closing means. The static cooling enables that the optical elements can be arranged within a closed space which reduces the problems of dust, and on the other hand there will be no need for double walls with air cooling channels, whereby the volume and weight will be minimized. In a preferable embodiment the Brewster polarizer comprises a plurality of spaced thin plano-parallel glass plates which substantially cover the cut opening. It is preferable if the light source is a metal halogen bulb. The spectral distribution of the lamp can be shifted to a biologically favorable range if the bulb in operation is underheated so that while operating the color temperature thereof is between about 3000 and 3200°K. The utilization of the available space gets better by said toroid transformer for supplying the light source with a small voltage, and electronic circuits for operating the light source can be arranged in the hollow space of the rectangular portion of the first tube. The operational properties will improve if the electronic circuits comprise a timer for adjusting length of lighting periods of the light source and a circuit for providing delayed rising of the current through the light source. The manufacture will be easy if the reflector is made of a thin metal sheet and the heat dissipating means comprises a member made of a heat conducting metal fitting in the interior of the first tube and the member has an upper recess in conformity with the shape of the rear side of the reflector, and these conforming surfaces are attached to each other so that a good heat conductive coupling is established between them, cooling grooves are provided at the cylindrical outer periphery of the member, and a central bore is formed in the member for receiving a mount which holds the light source, and a toroidal recess is formed at the bottom of the member to receive the toroid transformer. It is also preferable if the rectangular member is made of an aluminum alloy and it has a cylindrical bottom part extending to the bottom of the first tube. The invention will now be described in connection with a preferable embodiment thereof, in which reference will be made to the accompanying drawings. In the drawing: Fig. 1 shows the embodiment of the invention, partly in section, Fig. 2 is a sectional top view taken along line VIII-VIII of Fig. 1, and Fig. 3 is an enlarged sectional detail through the Brewster polarizer. The therapeutic lamp according to the invention is illustrated in Figs. 1 and 2. This lamp 100 has a body or housing which can consist of two conforming and matching parts of a plastic or foam plastic material attached together to form an integral body. The housing 101 comprises a vertical tube portion 103 and a shorter tube portion 102 which has an axis that closes twice the Brewster angle of about 114° with the axis of the vertical tube portion 103. The two rear portions of the tubes 102, 103 are cut in a common plane and a Brewster polarizer 104 covers the cut hole which has an elliptical contour. The structural design of the Brewster polarizer 4 will now be described with reference to Fig. 3. The Brewster polarizer 104 comprises a few number (e.g. five) thin plano-parallel glass plates 23 which have elliptical form and are spaced from one-another. A closing plate 124 is arranged behind the glass plates 23 which can be made of a die-cast aluminum alloy and the closing plate 24 is attached to the tubes 2, 3 to provide a sealed closure for the elliptical opening. For attaining increased heat transfer the inner surface of the plate 124 is made black e.g. by electrolytic plating. The spacing between the respective glass plates 23 and between the rear glass plate and the closing plate 124, as well as between the so-obtained assembly and the elliptical cut surface of the tubes are provided by thin plastic stripes. The outer surface of the closing plate 124 i.e. which is at the opposite side of the plate relative to the glass plates 23 is provided with elongated cooling ribs 25 which extend substantially parallel to each other. The tube portion 102 comprises a light filter plate (not shown) in the frontal portion thereof to close the inner space of tube portion 102. The light filter plate is made of a yellow filter which is transparent only for the spectral components with wave lengths exeeding about 400-450 nm. The vertical tube 103 is substantially a hollow cylinder, however it comprises a rectangular frontal portion 103a defining an inner space communicating with that of the cylinder. The rectangular portion extends vertically up to the frontal and upper tube portion 102 and it provides a support therefor. The presence of the rectangular portion 103a increases the overall rigidity of the therapeutic lamp 100 and the hollow inner space thereof can be used for placing electronic circuits required for proper operation. The housing has a round support and mounting bar 140 which encircles the upper half of the frontal tube portion 102 so that it is forming integral part thereof along an engagement zone and when leaving the tube portion 102 the support bar 140 has a pair of vertical legs 141, 142 spaced corresponding to the diameter of the tube portion 102 and horizontal rods 143, 144 are attached to the ends of the legs 141, 142 which end in a forward projection 145 of the rectangular portion 103a. Such a design of the housing is preferable, since the lamp can have a stable position as shown in Fig. 7, in which the opening of the tube portion 102 is slightly inclined in upward direction, whereby for cosmetical applications the most frequent target i.e. the face of a subject can be illuminated directly so that the subject takes a very comfortable sitting position. A further advantage is the presence of the two spaced legs 141, 142 at which the lamp can be held comfortably, or a positioning device can be clamped to the legs. Last but not at least the round bar 140 lends the housing an aesthetically pleasing form. A reflector assembly 105 is provided which comprises a metal halogen light source 115, a reflector 110 with a paraboloid surface 111 and a mount 114 for the socket of the light source 115. The reflector 110 is made by a thin sheet material having the form of a rotational paraboloid. A support member 146 preferably made of a die cast aluminum is provided which has a sustantially paraboloid depression conforming to the rear side of the reflector 110. The reflector is attached to the member 146 e.g. by means of a heat conducting adhesive. The upper ring-like face of the support member 146 is pressed to a ring-like shoulder of the interior of the tube portion 103 via a sealing ring. Vertical grooves 147 extend along the outer surface of the member 146 which have a depth decreasing in upward direction as the wall thickness of the member gets smaller. The increased surface provided by the grooves 147 ensures sufficient cooling. The member 146 has a central bore for receiving the mount 114, by which the light source can be adjusted and positioned in such a way that the short filament thereof coincides with the focal point of the parabolic surface 111. The lower surface of the support of the support member 146 defines a toroidal depression, in which a toroid transformer 148 can be inserted and kept. Since the light source 115 is generally a low voltage type, a mains transformer is required. If this transformer is made as a toroid one, its form is ideal for being received in the support member, whereby substantial space can be spared and there will be no need for a separate power supply unit. In the embodiment shown in Fig. 1 the transformer 148 is fixed by a ring-like pressure plate 149 clamped by bolts 150 to the support member 146. The adjustment of the mount 114 can be made through the central opening of the plate 149 by means of an appropriate tool. The bottom of the support member 146 defines a cylindrical inner space communicating with the torodial recess so that the transformer 148 can be inserted easily. A closure plate 151 provided with cooling grooves is used to close the interior of the tube 103 and of the rectangular portion 103a. The good thermal coupling between the thin reflector and the support member 146 ensures an effective cooling, at least for the heat generated by the lamp 115 which has a nominal power of 50 W. Due to its small consumption and good efficiency the transformer 148 does not generate a significant amount of heat which could influence the thermal conditions. The vertical opening between the interiors of the tube portion 103 and rectangular portion 103a is closed by a vertical mounting plate 152 which holds a printed circuit board 153 for the components of the electronic circuits. The electronic circuits may comprise a voltage stabilizer, a delay circuit ensuring that the current increase and decrease occurs slowly in the lamp circuit, whereby the life time of the bulb will be longer, as well as a timer by which the on-time of the lamp can be adjusted. Adjustment knob 154 of the timer, a combined on-off switch and lamp 155 and a socket 156 for the power cord can be seen in Fig. 1. The therapeutic lamp according to the invention has an ergonomic design and it is capable of treating larger body areas (e.g. the whole face of a subject) in a short period of time. The closed constructional design prevents the optically active surfaces from being dusty or dirty during operation which ensures that the intensity of the output light remains unchanged during longer use. The operation of the therapeutic lamp 100 according to the invention is as follows: The light source 115 emitts visible and infrared light which is directed by the reflector 110 forward in axial direction so that the angle of incidence of the light on the Brewster polarizer 104 is equal to 57°. The glass plates 23 of the Brewster polarizer 104 reflect light in the direction of the axis of the tube 2 and this light is linearly polarized. The non-reflected portion of the light hits the black inner surface of the closing plate 124 and the heat generated thereby will be radiated away by the cooling ribs of the plate. Owing to the robust design and the high thermal conductivity of the closing plate 24, this latter will have a constant temperature with uniform distribution. A standard metal halogen bulb has a color temperature of about 3400°K when supplied by the nominal voltage. For the purposes of biostimulation it can often be more preferable if the color temperature is adjusted to a somewhat lower value e.g. about 3000-3200°K, since in case of a lower color temperature the spectral distribution of the radiated light is shifted towards the infrared range. Infrared light has a higher depth of penetration into the living tissues than visible light has. The lower color temperature can be provided by a slight underheating of the light source 115, whereby the expected life time of the bulb will be increased significantly.

Claims: 1. Therapeutic lamp for biostimulation with polarized light, comprising a light source (115) with a power substantially between 30 W and 300 W and being substantially a point source, a reflector (110) with a rotational paraboloid light reflecting surface defining a focal point and arranged behind the light source so that said focal point substantially coincides with said point source to reflect forward the majority of light emitted by said source in a parallel path, a Brewster polarizer (104) arranged in said path to generate polarized output light propagating in a predetermined direction and having a cross-section of at least 100 cm², a light filter plate being transparent for wavelength components exceeding 400-450 nm, and an integral housing preferably made of a plastic material and formed of a first tube (103) with a first axis and with a bottom end normal to said first axis and of a second tube (102) with a second axis forming with said first axis an angle being twice the Brewster angle, i.e. about 114°, said tubes having substantially equal and circular cross-sections and being attached to each other, said reflector (110) with said light source (115) being fixed in said first tube so that a sealed connection is provided therebetween, said first and second tubes being cut along a plane extending normal to the plane containing said first and second axes so that said plane cuts substantially the whole cross-sections of both tubes, said cutting plane forming substantially the same angle with said first and second axis, whereby an opening with an elliptical contour line is defined, a light diverting means closing said opening for diverting light arriving from said said reflector in said first tube to the axial direction of said second tube, said light diverting means comprising said polarizer (104) and comprising a closing plate (124) of a heat conducting material and having a heat dissipating increased rear surface, said light filter plate being arranged in the frontal section of said second tube (102) to close the inner space thereof, a toroid transformer (148) for supplying said light source (115) with a small voltage being arranged in the first tube (103) below said paraboloid surface (111), static heat dissipating means contacting said reflector (110) for providing operational temperature for said light source (115), said heat dissipating means comprising a metal closure plate (151) attached to said bottom end of said first tube to close the hollow cavity thereof, said closure plate (151) being provided with cooling grooves, said housing further comprising a pair of spaced legs (141, 142) extending from the frontal portion of said second tube downwardly substantially parallel to said first axis, said legs (141, 142) being extended by horizontal rods (143, 144), said first tube comprising a hollow rectangular portion extending along the frontal zone thereof and ending in said second tube, a horizontal projection (145) being extending out of the bottom of said rectangular portion (103a) to receive ends of said horizontal rods (143, 144), and electronic circuits for operating the light source being arranged in the hollow space of said rectangular portion (103a) of the first tube (103). 2. The therapeutic lamp as claimed in claim 1, wherein said Brewster polarizer (104) comprises a plurality of spaced thin plano-parallel glass plates (23) substantially covering said cut opening. 3. The therapeutic lamp as claimed in claim 1, wherein said light source (115) is a metal halogen bulb. 4. The therapeutic lamp as claimed in claim 3, wherein the bulb is underheated when operated so that in operation the color temperature thereof is between about 3000 and 3200°K. 5. The therapeutic lamp as claimed in claim 1, wherein said electronic circuits comprise a timer for adjusting the length of lighting periods of said light source and a circuit for providing delayed rising of current through the light source. 6. The therapeutic lamp as claimed in claim 1, wherein said reflector (110) is made of a thin metal sheet and said heat dissipating means comprises a member (146) of a heat conducting metal fitting in the interior of the first tube (103) and said member has an upper recess conforming to the shape of the rear side of the reflector (110) and said conforming surfaces are attached to each other so that a good heat conductive coupling is established between them, cooling grooves (147) being provided at the cylindrical outer periphery of said member (146), and a central bore is formed in the member for receiving a mount (114) holding said light source (115), a toroidal recess is formed at the bottom of said member (146) to receive said toroid transformer (148). 7. The therapeutic lamp as claimed in claim 6, wherein said member (146) is made of an aluminum alloy and has a cylindrical bottom part extending to the bottom of said first tube (103).

Inventors: KOLTA, PETER, KREBSER, WERNER, LANTOS, MICHAEL
Applicants: "HARRIER" GMBH GESELLSCHAFT FUER DEN VERTRIEB MEDIZINISCHER UND TECHNISCHER GERAETE
Application year: 1988
Main classification: A61N5
IPC codes: F21V9, F21V29, A61N5, F21V7