DE3810297A1 - Reflector system and luminaire having the reflector system - Google Patents

Abstract

To improve the degree of utilisation of a paraboloid reflector R1, an ellipsoid reflector part R2 is arranged opposite the paraboloid reflector part in such a manner that the optical axes of the two reflector parts coincide. The light source is located in the primary focus F2 of the ellipsoid reflector part whose secondary focus F3 coincides with the focus F1 of the paraboloid reflector part R1. The ellipsoid reflector part R2 is considerably smaller than the paraboloid reflector part R1. The reflector system avoids any stray light. <IMAGE>

Description

The invention relates to a reflector system for illuminating egg nes object with a small beam angle according to Preamble of claim 1 and a lamp with the Reflector system.

Such reflector systems generally use a para boloid reflector, which is shown schematically in Fig. 1. If, in the case of a paraboloid reflector, a point light source 1 is arranged in the focal point ( F ), the radiation 2 is reflected parallel to the optical axis 3 , as shown in FIG. 1.

The parabola is defined by the following equation:

y ² = 2 px (I)

where p is the parameter of the parabola.

Because the parabola applies to the focal point

f = p / 2,

can express the equation of the parabola as follows will:

y ² = 4 fx (II).

If two values are set from the parameters x , y and f , the third value can be calculated using equation (II). The opening diameter d of a paraboloid reflector be 2 y , while x indicates the reflector depth L ₁ .

A paraboloid reflector has the disadvantage compared to an ellipsoid reflector that the former reflector has a lower degree of utilization of the radiation energy due to the greater slope of its curve. In order to increase the degree of utilization of the radiation energy, the reflector depth L _{1 has been} increased in paraboloid reflectors, but the diameter d of the opening 4 ( FIG. 1) inevitably also increases. However, the size of the diameter d of a reflector is limited for technical or optical reasons, so that the degree of utilization of the radiation energy cannot be increased arbitrarily in this way. In addition, large paraboloidal reflectors have a two-th opening 5 ( FIGS. 3 to 5) in the region of the apex for cost reasons, so that the light source can be replaced, while smaller reflectors are firmly connected to the light source, so that a Light source at the end of its useful life can only be replaced together with the reflector.

On the other hand, if the size of the paraboloid reflector is increased to increase the degree of utilization of the radiation energy, the degree of utilization is reduced again by the second opening 5 provided for cost reasons, so that no satisfactory solution to the problem is achieved in this way.

Other measures have also been investigated in order to improve the degree of utilization of the radiation energy in a paraboloid reflector. The smallest possible beam angle can be achieved if a short rod-shaped light source is arranged along the optical axis. This arrangement is correct from the point of view of increased utilization, since such a light source as that of a low-voltage halogen lamp has a toroidal light distribution, as shown in FIG. 2. As measurements show, approximately 90% of the total radiation energy is emitted within an angle q of between 30 ° and 150 ° in such a light source. In FIG. 2, the light intensity is plotted at an angle of 0 ° to 180 °.

It has also been examined whether the degree of utilization of the radiation energy can be improved by changing the focal point. FIGS. 3 to 5 show the radiation in the para boloid reflectors with focal points f of 10, 20 and 30 mm. Since the diameter d of the radiation opening is set to 130 mm and the diameter d 2 is fixed to the lamp fixing to 30 mm. The radiation has been changed from 30 to 150 ° by 10 °.

From Figs. 3 to 5 shows that the position of the focal point practically no influence on the height of the degree of utilization of the radiation energy has. This is about 50 to 60% in all three illustrated cases.

The arrangement of FIG. 3 has the disadvantage that too much radiation is emitted to the rear. As a result, the lamp holder, the transformer or other components can be damaged by heat radiation from an incandescent lamp or by UV radiation from a discharge lamp. It is therefore expedient to set the focal point F to a point which lies between the focal points of FIGS. 4 and 5. However, this has the disadvantage that a considerable part of the radiation is emitted directly forward from the light source. This direct radiation is identified in FIGS . 3 to 5 with the reference number 6 . This scattered light has the disadvantage that it dazzles and blurs the boundary of the light spot which is formed by the reflected radiation 2 . To prevent this scattered light, the head end of the glass bulb of a light source can be coated dark or a cap can be arranged in front of the light source, which is attached to a holder. However, these are not satisfactory solutions.

The present invention has for its object a Re to further develop the reflector system of the type under consideration so that the degree of utilization of the radiation energy is considerably increased, while at the same time the disadvantages described above known measures should be avoided. In addition, one Luminaire can be specified with the reflector system.

According to the invention, these tasks are performed by means of the of claims 1 and 15 specified features. Before partial developments of the invention are in the Unteran sayings marked.

The reflector system according to the invention contains in addition to that Paraboloid reflector part an ellipsoid reflector part, on the primary focus is the light source. The opening of the ellipsoidal reflector part has a much smaller one Diameter than the opening of the paraboloid reflector part and is arranged opposite the paraboloid reflector part so that the two optical axes coincide and that the sekun the focal point of the ellipsoidal reflector part with the focal point of the paraboloid reflector part coincides. Is located the primary focus of the ellipsoidal reflector part in the Near its opening.

In the reflector system according to the invention, the groove is reached Degree of radiation energy about 90%, a small one Beam angle is maintained. Nothing arises Scattered light that blurs the boundary of the light spot let.

In addition, the reflector system according to the invention has the following Advantages:  

• a) the reflector system can be manufactured inexpensively, because the paraboloid reflector part in the apex area none Must have opening so that the manufacture of the Parabo loid reflector part is considerably facilitated. This works particularly in the manufacture of glass reflectors out. In addition, the metal ellipsoidal reflector part, consist of aluminum sheet, for example, so that Ellipsoid reflector part in a simple operation can be pressed.
• b) The heat radiation or UV radiation from the light source can be filtered out practically one hundred percent, since any radiation from the light source falls into the paraboloid reflector part if the following measures are taken:
  • - The ellipsoidal reflector part is made of metal, so that not only the visible radiation, but also the heat radiation or UV radiation from the light source is passed onto the paraboloidal reflector part.
  • - The paraboloid reflector part consists of a transparent material such as glass and is provided on the reflection surface with a cold-light mirror coating or with a wavelength-selective coating that allows selected spectral ranges to the rear.
• c) If the paraboloid reflector part with the wavelength ver reflective coating on the reflective surface ver is a pure color of light or radiation a sharply defined wavelength interval.
• d) The reflector system according to the invention is absolutely glare free because the light source is from the ellipsoidal reflector part is covered so that it cannot be seen from the outside. In addition, as mentioned above, there is no litter light generated.  
• e) By changing the distance of the facing each other End faces of the two reflector parts can be easily Way the beam angle can be changed.
• f) The useful life of the light source is not determined by a Overtemperature affected because the light source is not at Bottom of a reflector or in a housing, but by means of a holder, surrounded by air. If the outer surface of the ellipsoidal reflector part is dark is colored, the heat from the surface can also us be discharged into the air.
• g) The housing can be downsized because the paraboloid re has a small reflector depth and neither Lamp holder another fixture the socket in the housing are required.
• h) The light source can be replaced easily because it is not sitting deep in a reflector, but rather it can be complete with the small ellipsoid reflector part be replaced.

The invention is described in more detail below the drawing. It shows or show:

Fig. 1 is a paraboloid reflector;

Figure 2 is a toroidal light intensity distribution of a low-voltage halogen lamp.

Fig. 3 to 5 paraboloid reflectors with different focal points;

Fig. 6 shows an inventive optical system;

Fig. 7, the radiation in the angle q from 30 to 100 °, which is reflected by the first closing ellipsoid reflector part and by the paraboloidal reflector part of the reflector it inventive system;

Fig. 8 is a view similar to Figure 7 with radiation in the interval In the angle q from 100 to 150 °, which is directly radiated from the light source on the parabolic reflector section and reflected from there.

Fig. 9 to 25 radiation of the reflector system according to the invention in different selection parameter, and

Fig. 26 shows a lamp with the reflector system according to the invention in a schematic front view and a partially sectioned side view of the region of the reflector system.

As shown in Fig. 6 in a purely schematic front view and a side view, the reflector system according to the invention consists of a paraboloid reflector part R ₁ and an oppositely arranged ellipsoid reflector part R ₂ , the optical axes of which coincide. In the primary focal point F _{2 of} the ellipsoid reflector part R ₂ is the light source 1 , the radiation passing through the edge of the opening 8 of the ellipsoid reflector part R ₂ with the optical axis enclosing the angle p . The opening 8 of the ellipsoidal reflector part R ₂ has a substantially smaller diameter d 2 than the opening 7 of the paraboloidal reflector part R ₁ . The secondary focal point F _{3 of} the ellipsoid reflector part R ₂ coincides in the illustrated embodiment of the invention with the focal point F _{1 of} the para boloid reflector part R ₁ . The primary focal point F _{2 of} the ellipsoidal reflector part R ₂ is located near the opening 8 .

In order to be able to compare the performance of the reflector system according to the invention with a paraboloid reflector shown in FIGS. 1 to 5, the opening diameters of the reflector system according to the invention are set such that

• - The opening diameter d 1 of the paraboloid reflector part R _{1 is} equal to the opening diameter d of the paraboloid reflector, and
• - That the opening diameter d 2 of the ellipsoidal reflector part R _{2 is} equal to the diameter of the opening of the lamp attachment.

This results in the following values:
Paraboloid reflector part: opening diameter d 1 = 130 mm;
Focal point f 1 = 35 mm;
Ellipsoidal reflector part: opening diameter d 2 = 30 mm;
Large semi-axis a = 15.231 mm;
Small semi-axis b = 15.0 mm;
Focal point f 2 = 12.6 mm;
Distance between the two reflector parts L ₄ = 8.1 mm.

From Fig. 7, it is clear that only a minor part of the radiation has been blocked by the ellipsoid reflector part R _2.

FIG. 8 shows that the ellipsoid reflector part R ₂ does not cause any significant interference in the radiation and that there is only a slight deviation from the optical axis 3 with respect to the direct radiation. The deviation is only 4 to 5 °, whereby this radiation is not deflected outwards but inwards. Therefore, this radiation, designated by the reference numeral 9 , forms a light spot on a screen that is almost as small as the radiation 10, for example at a distance of approximately 1 m.

The setting of the parameters of the reflector system according to the invention is described below, reference being first made to FIG. 6.

First of all, the opening diameter d 1 of the paraboloid reflector part R ₁ is expediently set, in the present example to 130 mm. The opening diameter d 2 of the elliptical reflector part R ₂ should be as small as possible, namely less than about 30% of the diameter d 1 of the paraboloid reflector part R ₁ . d 2 is set at 30 mm here.

The angle p which the direct radiation passing through the opening edge forms with the optical axis should be between 60 and 90 ° (in the present case 80 °).

The corresponding ellipsoid can be calculated with the specified diameter d 2 and the angle p . A semi-ellipsoid should be used since in this case the difference between the light spot formed by the radiation which has been reflected by the reflecting surface of the reflector part R ₂ and the light spot formed by the direct radiation is minimal .

With the following formula the corresponding ellipse is again given:

b = d 2/2 = 15 mm (III)

a = b / sin (p) = 15.231 mm (IV)

The distance of the opening from the primary focal point F ₂ corresponds to the linear eccentricity e of the ellipsoid and is calculated as follows:

e = b / tan (p) = 2.645 (V)

This value also corresponds to the distance of the opening 8 from the secondary focal point F ₃ outside the ellipsoidal reflector part R ₂ .

The distance f 2 of the primary focus F ₂ from the apex is calculated as follows:

f 2 = a - e = 12.586 mm (VI)

The distance L ₂ of the primary focal point F ₂ from the opening of the paraboloid reflector part R ₁ is calculated as follows:

The distance L ₃ of the opening 7 of the paraboloid reflector part R ₁ from the secondary focal point F ₃ of the ellipsoid reflector part is thus calculated as follows:

L ₃ = L ₂-2 e = 6.171 mm (VIII)

The focus F ₁ coincides with the focus F ₃.

With L ₃ and d 1, the other parameters of the paraboloid reflector part, namely the distance f 1 of the focal point and the reflector depth L ₁ can be calculated according to the following equations:

It follows

f 1 = 35.732 mm
L ₁ = 29.560 mm.

In order not to drop the direct radiation that passes the edge of the ellipsoidal reflector part R ₂ at angle p directly onto the edge of the paraboloidal reflector part R ₁ , but onto the reflection surface, and to have a rounded size of the distance of the focal point f 1 to obtain, the value f 1 'can be slightly smaller than the value f 1 calculated above.

In the present case, the focal point f 1 'is fixed at 35.0 mm, while the reflector depth L ₁ ' is 30.179 mm.

The distance L ₄ between the openings of the two reflector parts R ₁ and R ₂ is calculated as follows:

L ₄ = f 1 ′ - L ₁ ′ + e = 8.094 (XI)

This distance L ₄ does not have to be observed exactly, but it can also be somewhat smaller than the calculated value.

Figs. 9 and 10 show the radiation at a distance of L ₄ - 2 mm.

The tolerance of the parameters is then considered.

a) Ellipsoid reflector part

The reflector shape should be a semi-ellipsoid for the reason given above. Otherwise, the cone of light of the reflected radiation is much smaller than that of the direct radiation, and the reflected radiation is concentrated in the region of the center of the paraboloid reflector part R ₁ .

b) angle p

The closer the angle p approaches 90 °, the higher the degree of utilization. At an angle p of 90 °, the El lipsoid reflector part R _{2 is} approximately a hemisphere. The reflected radiation comes back to the light source.

At an angle p greater than 90 °, the ellipsoid reflector part R _{2 is arranged} in the paraboloid reflector part R ₁ . In this case the loss is too great.

The angle p should be greater than 60 °.

FIGS. 11 and 12 show an arrangement with an angle p equal to 60 °, wherein the two reflector parts are far apart. In this case, the loss and the deviation of the radiation from the optical axis are too great.

c) ratio of the diameter d 2 to d 1

The diameter should be equal to or less than 2 × y , which can be calculated using the following equation:

in which

As shown in FIG. 2, the radiation of the angle q between 60 and 120 ° has a substantially greater energy than the radiation of the angle q between 0 and 30 °. This limit is approximately an angle q of 45 °.

The above-mentioned equation can be used to determine the height y of the radiation which is emitted from the light source at an angle q = 45 ° and which, after reflections by the ellipsoidal reflector part and the paraboloidal reflector part, passes the ellipsoidal reflector part at this height.

Figs. 13 to 15 show the radiation of the angle q = 45 ° d at diameters 2 of 30, 40 and 50 mm.

Figs. 16 and 17 show the radiation of the angle q between 30 and 150 ° and a diameter d 2 of 40 mm.

The calculation shows that d 2 should have a value = 30% of d 1.

d) focus f 1 'of the paraboloid reflector part R ₁

The focal point should remain within the value f 1 +/- 30% calculated by the formula (IX).

If f 1 'is greater than f 1, the radiation falling on the edge of the ellipsoid reflector part R ₂ does not pass onto the reflection surface of the paraboloid reflector part R ₁ , but extends between the two reflector parts. If f 1 'is more than 130% of f 1, the loss is too large, as shown in FIGS. 18 and 19.

If the focal point is only 70% of f 1, the ellipsoid reflector part R ₂ lies in the paraboloid reflector part R ₁ . The losses and the deviation are still acceptable, but a smaller paraboloid reflector part can be used to achieve the same degree of utilization, since the radiation from the light source does not fall on the entire reflection surface of the paraboloid reflector part ( FIGS. 20 and 21) .

e) Distance L ₄ 'between the reflector parts

If the distance L ₄ 'is set to a larger value than calculated according to the formula (XI) for L ₄ , a light cone with a larger beam angle can be achieved. The Figs. 22 and 23 show the radiation at a distance of L ₄ + 3 e.

If a high degree of utilization is to be maintained, the paraboloid reflector part can be enlarged slightly so it is avoided that radiation between the two reflector len exits.

If a very small beam angle is to be achieved, the distance must be set at around L ₄ - e . The radiation 10 extends slightly outwards, while the radiation 9 extends inwards, as FIGS. 9 and 10 show.

If the distance is less L ₄ - 3 e , all radiation is emitted to the outside. This creates a dark zone in the light cone, as shown in FIGS. 24 and 25. This means that the distance L ₄ 'must be greater than L ₄ - 3 e .

f) size of the light source

The length of the light source should be as short as possible and be less than 2e. Otherwise, the radiation Ver lust too big.

In the case of a light bulb, the diameter of the filament should be 3/4 the helix length, so the loss described above is kept low. The upper limit of this ratio depends depending on the manufacturing possibilities.

Fig. 26 shows a cylindrical lamp 10 with the inventive reflector system. The paraboloid reflector part R ₁ is thereby held vertically in the lamp 10 , since its edge 11 is fastened to the lamp wall 13 by means of a ring 12 .

The ellipsoidal reflector part R ₂ is connected to a base 14 . A low-voltage halogen incandescent lamp 15 is fastened in the base 14 in such a way that its incandescent filament 16 is in the focal point F ₂ .

The base 14 is inserted into a socket 17 which is attached to a bracket 18 of the ellipsoidal reflector part R ₂ and is thus adjusted with respect to the paraboloidal reflector part R ₁ .

A front ring 19 has two slots, which are in the drawing voltage up and down and in which the bracket 18 is inserted, which is slidably held in the slots so that the light cone can be changed. The bracket 18 can be removed from the lamp 10 in order to replace the incandescent lamp 15 , the base 14 and the ellipsoidal reflector part R ₂ .

The bracket 18 is gebil det by a sheet of a small thickness. The bracket 18 holds the base 14 securely and only slightly blocks the rays coming from the paraboloid reflector part R ₁ .

The bracket 18 is electrically connected to the socket 17 and supplies electricity to the incandescent lamp. In the slot, a spring is installed, which supplies the bracket 18 with current, which leads from a network connection to a cable inserted into the second ring 19 (not shown in the drawing).

Since the voltage is only about 12 volts, the bracket 18 need not be insulated.

The light bulb can include the base and the reflect tors attached directly to the bracket. Of course must the bracket is neither a conductor nor formed by a sheet be. Rather, it can also consist of a tube through which a cable is routed.

The ellipsoidal reflector part R ₂ consists of a sheet, for example made of aluminum, the reflection surface is machined to a gloss. As a result, not only the rays of the visible wavelength range but also all rays from the light source can be directed to the paraboloid reflector part R ₁ .

The paraboloid reflector part R ₁ , on the other hand, consists of a transparent material, for example of glass, the reflection surface of which is provided with a dichroic coating.

Through this combination of the two reflector parts, Wär radiation and radiation of undesired wavelength ranges the light source almost completely to the back of the lamp be allowed through.

Claims (19)

1. reflector system for illuminating an object with a small beam angle, with a paraboloid reflector part and a light source arranged in front of it, characterized in that an ellipsoid reflector part ( R ₂ ) is arranged opposite the paraboloid reflector part ( R ₁ ) in such a way that its optical axis coincides with that of the paraboloid reflector part ( R ₁ ) that the ellipsoid reflector part ( R ₂ ) is smaller than the paraboloid reflector part ( R ₁ ) that the light source ( 1 ) at the primary focus ( F ₂ ) of the ellipsoidal reflector part ( R ₂ ) is arranged, and that the secondary focal point ( F ₃ ) of the ellipsoidal reflector part ( R ₂ ) essentially coincides with the focal point ( F ₁ ) of the paraboloidal reflector part ( R ₁ ). 2. Reflector system according to claim 1, characterized in that the ellipsoidal reflector part ( R ₂ ) has the shape of a semi-ellipsoid. 3. Reflector system according to claim 1 or 2, characterized in that the angle ( p ) which the direct radiation of the light source ( 1 ) along the edge of the opening ( 8 ) of the ellipsoidal reflector partly ( R ₂ ) includes with the optical axis , is determined by the following inequality: 90 <p <60 °, the ellipsoid reflector part ( R ₂ ) having the following axes:

• - small semi-axis b = d 2/2
  ( d 2 = opening diameter of the ellipsoid reflector part R ₂ )
• - large semi-axis = b / sin (p).

4. Reflector system according to one of claims 1 to 3, characterized in that the opening diameter ( d 2) of the ellipsoidal reflector part ( R ₂ ) fulfills the following condition: d 2 ≦ 2 y , where y is given by the following equation: in which
f 1 equals the distance of the focal point (F ₁) of the paraboloid reflector part (R ₁) from the apex, is. 5. reflector system according to one of claims 1 to 4, characterized in that the distance ( f 1) of the focal point ( F ₁ ) of the paraboloid-Re reflector part ( R ₁ ) within the value determined by the following equation (f 1) +/- 30% remains: in which 6. Reflector system according to one of claims 1 to 5, characterized in that the distance (L ₄ ') between the two reflector parts (R ₁, R ₂) is greater than the value calculated according to the following formula (L ₄-3 e) : L ₄ = f 1 - L ₁ + e , where 7. reflector system according to claim 6, characterized in that the distance ( L ₄ ') is approximately L ₄ - e . 8. Reflector system according to one of claims 1 to 7, characterized in that the light source ( 1 ) is arranged so that its longitudinal axis coincides with the optical axis of the ellipsoidal reflector part ( R ₂ ). 9. reflector system according to claim 8, characterized in that the length of the light source ( 1 ) is less than 2 e . 10. Reflector system according to one of claims 1 to 9, characterized in that the filament ( 16 ) of an incandescent lamp ( 15 ) has a length as a light source which is equal to or greater than 3/4 of the diameter of the filament. 11. Reflector system according to one of claims 1 to 10, characterized in that the ellipsoidal reflector part ( R ₂ ) consists of metal. 12. The reflector system according to claim 11, characterized in that the outer surface of the ellipsoidal reflector part ( R ₂ ) is colored dark. 13. Reflector system according to one of claims 1 to 12, characterized in that the paraboloid reflector part ( R ₁ ) consists of a transparent material and is coated on the reflection surface with a cold light mirror coating. 14. Reflector system according to one of claims 1 to 13, characterized in that the paraboloid reflector part ( R ₁ ) consists of a transparent material and is coated on the reflection surface with a wave-length-selective coating. 15. Luminaire with the reflector system according to one of claims 1 to 14, characterized in that the ellipsoidal reflector part ( R ₂ ) is formed by a reflector lamp. 16. Lamp according to claim 15, characterized in that a bracket ( 18 ) is arranged on the front of the lamp and is provided with a lamp holder. 17. Lamp according to claim 15 or 16, characterized in that the bracket ( 18 ) consists of sheet metal and is arranged on the front of the lamp in such a way that its wider side runs parallel to the lamp axis. 18. Luminaire according to claim 16 or 17, characterized in that the bracket ( 18 ) serves as a current conductor. 19. Lamp according to one of claims 15 to 18, characterized in that the lamp has at least two slots on its front, in which the bracket ( 18 ) is inserted such that it can be moved forwards and backwards.