US1806384A - Shadowless lighting apparatus - Google Patents

Description

May 19, 1931.. v H. L. M. J. BENARD 1,806,384

'SHADOWLES S L .i GHT ING APPARATUS Filed April 19, 1928 5 .5 lnven/z'or 1 E an/m l M11 0 fie'numd Patented May 19. 1931 UNITED STATES PATENT 01 F105:

' HENRI LUGLIEN MARIE JOSEPH BEN'ARD, OF PARIS, FRANCE, ASSIGINOR TO ANCIENS ETABLISSEMENTS BARBIER, BENARD & TURENNE, SOCIETE ANONYME, 0F PARIS, FRANCE, A JOINT-STOCK COMPANY OF FRANCE SHADOWLESS LIGHTING APPARATUS Application filed April 19, 1928, Serial No.

The present invention relates to certain improvements applicable to lighting apparatus which do not throw shadows, and are more particularly intended to lighting up operating benches or the like.

These lighting apparatus broadly comprise, as is well known, one or more central luminous sources about which is located the re flectng system which reflects the luminous m rays emanating from the luminous source on to a given portion of the operating bench at different angles, whilst an optical system, constituted by optical lenses or by combination of mirrors and reflectors indifferently,

is preferably inserted between the luminous source or sources and the above mentioned reflecting system.

A first improvement with which the present invention is concerned is intended to render these lighting apparatus more secure and such improvement essentially consists in fitting up a shadowless lighting apparatus with an emergency lighting device constituted by one or more luminous sources completely independent of the principal luminous source or sources. When these auxiliary lighting sources are electrical, they are mounted in a shunt circuit ofthe circuit of the main sources in order to render them independent. .More advantageously, the auxiliary sources may be mounted on a totally separate circuit fed for example by a battery of accumulators.

The emergency lighting sources will be preferably arranged in such wise that the light they emit shall be reflected back at different angles onto the surface to be lit up, said emergency lighting source thus itself providing to a certain extent shadowless illumination. The object of this emergency source of illumination when it operates in conjunction with the principal lighting system, Wlll likewise be to project light on the portions fringing the operating bench, which are nor- ;5 mally not lit up.

Another improvement forming the ob 'ect of the present invention aims at obviatin another drawback obtaining with devices 0 this nature as at present known and which resides in the fact that they give off great heat Wl'llCll 271,277, and in France February 10, 1928.

may seriously inconvenience the surgeons. This heat is given off by the infra-red rays emitted by the principal luminous source or sources. This improvement consists in combining with a lighting apparatus that does not throw shadows, a device inserted in the path of the luminous rays between the luminous emitting source or sources and the surfaceto be lit up, such device being capable of absorbing the heatcarried by said rays.

According to a form of construction, the heat absorbing device is constituted by heat absorbing glass which absorbs the infra-red heat rays, such glass assuming the form of a sleeve of suitable thickness surrounding the luminous source, an annular space being left between theluminous source and the sleeve, through which a suiiiciently strong current of air is passed to get rid of the heat.

Said heat absorbing glass might be applied, with the same end in View, to the construction of the silvered reflecting surfaces as at present used, the infra-red heat rays being then arrested during their double passage through the glass.

In this case, the reflecting surfaces are cooled by placing them in contact with a sheet of copper provided with fins or in contact with a substance having a great latent heat of fusion. I

In the accompanying drawings, forms of construction of the various improvements in accordance with the invention have been illustrated diagrammatically and merely by way of example.

In these drawings Fig. 1 is a longitudinal sectional elevation of a lightin apparatus which does not throw shadows, ofdmown type, and fitted u with an emergency lighting system in con ormance with the invention.

Fig. 1 shows the feeding circuits of the principaland emergency lighting apparatus respectively. I

Fig. 2 shows a form of construction of the device for absorbing the heat.v

gig. 3 shows an alternative form of Fig. 2 an Fig. 4 another alternative.

The shadowless lighting device illustrated in Fig. 1, essentially comprises, in the known manner, a central luminous source 1 about which an optical system is arranged, for example a Fresnel annular lens 2 which throws the luminous rays emitted by the source 1 on to a reflector 3 either conical or having a plurality of'facets, in a horizontal or practically horizontal sheet. In its turn, the reflector 3 reflects the luminous rays, c0ncentrating them at the same time, on to a comparatively small surface of the operating bench 4. This surface is consequently lit up without shadows.

This is a known type of shadowless lighting device, but it should be noted that the .improvements which will be described hereinafter are not solely adaptable to this type of device, but are on the contrary adaptable to all devices of the same type whatever may be the particular construction either of their central luminous source or of the intermediate optical device and the outer reflecting system.

According to the invention, the illuminating apparatus is fitted up with an emergency lighting system preferably constituted by a plurality of luminous sources such as 5 whose circuit is so formed that said electric lamps 5 shall be completely independent of the principal source 1. To this end, their circuit may be shunted across the circuit of the source 1. It will be more advantageous to render the circuit of the lamps 5 completely separate from that of the lamp 1 and it may be fed, for example, through a'battery of accumulators. Under these conditions, whatever may be the cause of the stoppage of the source 1, the auxiliary lamps 5 will give the requisite emergency illumination. This arrangement ob viates the drawback obtaining with the devices known hitherto with which operations were sometimes interrupted on account of a breakdown in the lighting of the principal source 1. With the above mentioned device, when the source 1 fails, the lamps 5 will give sufficient light to enable the surgeons to continue operating." The lamps 5 will moreover be so located that they provide by themselves light to a certain extent without shadows.

Again, it should benoted that said lamps 5, when they are used, in conjunction with the luminous source 1, light up to advantage the portions fringing the operating bench which a-re'normally not lit up by the principal luminous source 1.

In certain 'cases, it may be of advantage toimprovement with which the invention is'concerned which enables the heat given off by the principal luminous source or sources 1 to be absorbed, has been illustrated in Figs. 2 to 4.

The heat given off by the luminous source 1 may likewise be absorbed by means of glass composed of silica, sodium oxide, calcium oxide, arsenious oxide and iron oxide and which absorbs the infra-red heat rays emitted by the source 1.

In the case illustrated in Fig. 2, a cylindrical sleeve 8 made of glass of this composition is inserted between the Fresnel annular lens 2 and the source 1. The luminous rays emitted by the source 1 are obliged to pass through said sleeve which cuts off the heat rays. In order to prevent the sleeve 8 frbm heating up, a fairly strong current of air is passed through the space provided between the sleeve 8 and-the luminous source 1 whereby the heat absorbed is conducted away.

In order to absorb the heat, the device illus- 1 cooling fins or with any other substance possessing a great latent heat of fusion.

Finally, as illustrated in Fig. 4, the abovementioned glass of special composition may take the form of a disc 9 closing the lower part of the cupola formed by the reflector 3. In this instance likewise, the luminous rays are obliged to pass through the glass and the heat rays are consequently arrested. Moreover, the glass might be arrangedin any other manner, it being essential that the rays emitted by the luminous source 1 be obliged to pass through it.

It will be readily realized that with any one of these devices, the luminous rays which are concentrated on the operating bench do not carry .heat with them and that they are consequently not liable to inconvenience the surgeons even after a considerable length of time.

As has been already said, it is evident that the improvements described above as applied to a special type of shadowless lighting device, are applicable without being modified or only with unimportant modifications of detail, to all shadowless lighting devices whatever their particular construction may It is moreover self evident that the-in ent'ion has only been described and illustrated here in a purely explanatory but by nomeans I limitative' manner, and hat itcould be'subjected to various modificati ns of detail with- 4 out departing from the spirit thereof.

I claim:

1. In a lighting device, the combination with a principal light source, an optical condensing means adapted to condense light rays emitted by said source, and a system of reflecting mirrors adapted to reflect said rays on to a surface so situated relative to said principal lighting source as to receive shadowless illumination, of emergency light sources completely independent of said principal source and so disposed with respect to said reflecting mirrors as to contribute substantially shadowless illumination to said surface. 2. In a lighting device,the combination with a principal electrical light source, an optical condensing means adapted to condense light rays emitted by said source, and a system of reflecting mirrors adapted to reflect said rays on to asurface so situatedrelative to said principal lighting source as .to receive shadowless illumination, of emergency electrical light sources completely independent of said principal source and so disposed with respect to said reflecting mirrors as to contribute substantially shadowless illumination to said surface, and independent electric feeding circuits for said principal and auxiliary sources respectively.

3. In a lighting device, the combination of a lighting source, an annular Fresnel lens disposed about said source, a system of reflecting mirrors surrounding said Fresnel lens and adapted to reflect the light rays on to a surface so situated relative tosaid lighting source as to receive sha-dowless illumination, and a cylindrical sleeve inserted between said light source and said annular lens, said sleeve being made of heat absorbing glass adapted to cut oif the infra-red heat rays emitted by said source.

4:. In a lighting device, the combination of a lighting source, an annular Fresnel lens disposed about said source, a reflecting system surrounding said Fresnel lens and so disposed as to produce shadowless illumination on a given surface, and a cylindrical sleeve inserted between said source and said Fresnel lens and made of heat absorbing glass adapted to cut off the infra-red heat rays emitted by said source.

HENRI LUGLIEN MARIE JOSEPH BENARD.

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