Light conduction body and illumination unit with light conduction body

p0001The invention relates to a light guide body, whose cross-sectional area at least expands regionally steadily from a light entry surface to a light emitting surface and a light unit having at least one light emitting diode as a light source and a light guide body with.

p0002Light units, which are used for example in motor vehicle headlights Projection requiring high luminous flux and luminance. However, white LED light sources continue to have a low luminance and therefore require a large active source or chip area to produce the required light output. therefore, several LEDs are often used as light sources. In order to achieve the required for the operation of illumination intensity, is already introduced in the light source optically downstream optical system, the so-called primary optical system, a light intensity or luminance increase. For this purpose, an object intermediate level or a virtual image with shaped cutoff, shown a portion of eg visible on a wall measuring upper cut-off limit.

p0003The use of diaphragms has a negative impact on the efficient distribution of light in the optical system. Therefore, a light beam is formed with a highly transparent fiber-optic element, which is thrown by an imaging secondary optics such as on the road.

p0004From the <patcit id="pcit0001" dnum="DE102005017528A1"><text>DE 10 2005 017 528 A1</text></patcit> discloses a lighting unit with such a light guide body. During operation of the light unit formed at all edges of the illuminated region to not illuminated region hard transitions of illuminance.

p0005The present invention is therefore based on the problem to develop a fiber-optic element and a light-emitting unit, which allows for a clear-cut light-dark boundary of the illuminated area on the remaining edges a smooth transition of illuminance.

p0006This problem is solved with the features of the main claim. Given the light guide body comprises at least a portion having a curved guideline, in this area the curvature of the guideline is constant or where in this area the curvature of guideline decreases with increasing cross-section of the optical waveguide. Each straight line that intersects the light entry surface, passes through a boundary surface of the light guide out of the light exit surface. Moreover, the longest, the optical waveguide in the curved portion delimiting surface line longer than the maximum actual curvature of said surface line of the light guide divided difference from the circuit number and twice the largest critical angle of total reflection of the material of the light guide against or materials of at the optical waveguide adjacent environment.

p0007With such a structure of the light guide and the light unit, there is no light components that penetrate directly and without reflection the optical waveguide. All of the light is reflected at the interfaces of the light guide. The light is mixed, so that an illumination intensity distribution generated by the secondary optical system is independent of the Leuchtstärkcverteilung the light source. For all, the illuminated region limiting chiaroscuro transitions are controlled by the primary optics.

p0008Further details of the invention result from the dependent claims and the following description of schematically illustrated embodiments.<dl id="dl0001" compact="compact"><dt>Figure 1:</dt><dd>Dimetric view of a light unit;</dd><dt>Figure 2:</dt><dd>Side view of a light unit;</dd><dt>Figure 3:</dt><dd>Dimetric view of the light guide;</dd><dt>Figure 4:</dt><dd>View of the light-emitting region;</dd><dt>Figure 5:</dt><dd>Longitudinal section of the light guide with light source;</dd><dt>Figure 6:</dt><dd>Detail of light entry region;</dd><dt>Figure 7:</dt><dd>Detail of the light emission region;</dd><dt>Figure 8:</dt><dd>Light unit with a Fresnel lens as a secondary lens;</dd><dt>Figure 9:</dt><dd>Combined lighting unit for low and high beam.</dd></dl>

p0009The <figref idrefs="f0001">figure 1</figref> shows a diametric view and <figref idrefs="f0001">figure 2</figref> a side view of a light unit (10). These light units (10) are for example used in a headlamp for a motor vehicle. They include in these embodiments each have a light source (20), a primary optics (30) with a fiber-optic element (31) and secondary optics (80) each having a secondary lens (81; 82). In the illustration of<figref idrefs="f0001">figure 2</figref> is shown in a longitudinal section of the fiber-optic element (31). The primary optics (30) comprises in this illustration an additionally the optical waveguide (31) optically downstream of the primary lens (71).

p0010The light source (20) comprises, in these embodiments, a light emitting diode, for example a light emitting diode (21) with, for example, a light emitting chip (22). The LED (21) may also include a plurality of light-emitting chips (22), for example, are arranged in a square. The light-emitting chip (22) is, for example, a Lambert radiator, which emits light in a half-space. The light-emitting diode (21) has for example a cylindrical light distribution body (23), see FIG.<figref idrefs="f0004">figure 6</figref>, This stands in these embodiments, in a direction normal to the light emitting chip (22) not on the chip (22). The light distributing body (23) but can protrude 1.6 mm across the chip (22) in the light propagation direction (5), for example. The light distributing body (23) can also be rectangular with or without rounded corners, to be drop-shaped, etc. formed. The main light-emitting surface (24) is, for example parallel to the light-emitting chip (22).

p0011The individual light-emitting diode (21) generates, for example a luminous flux of 400 lumens. Instead of a single light-emitting diode (21), the light source (20) may also include a plurality of light emitting diodes (21). These may be white and / or RGB LEDs. The beam angle of each light-emitting diode (21) may be narrower than 180 degrees, for example, the light emission to be concentrated on a discharge angle of 150 degrees or 120 degrees.

p0012between the light distributing body (23) of the light-emitting diode (21) and the light guide body (31) in the embodiments, a narrow air gap (29), for example with a width smaller than five tenths of a millimeter. This air gap (29) is part of the light guide body (31) adjacent area (1). The light distribution body (24) may be present even at light distribution (31). The main light-emitting surface (24) of the diffuser (23) and the end face (32) of the fiber-optic element (31) are arranged parallel to one another here. The gap (29) can also be filled with a material whose refractive index is higher than the refractive index of air, for example, 1.1.

p0013The light-guiding body, see. <figref idrefs="f0002">figure 3</figref>, Consists of a thermoplastic material, such as polymethyl methacrylate (PMMA), polycarbonate (PC) or, for example modified polymethyl methacrylimide (PMMI). has the material of the formed for example as a solid body fiber-optic element (31) as the use of PMMA optical refractive index of 1.49. The outer surface (33) of the fiber-optic element (31) borders in the embodiments directly to the optical waveguide (31) surrounding air. The environment (1) of the optical waveguide (31) has thus in these embodiments, a refractive index of 1. The light-guiding body (31) can also be encapsulated by a second body, which for example has a lower refractive index than the light guide body (31). Also, the light-guiding body (31), a coating, for example, include on its outer surface (33) has a mirror coating.

p0014The light-guiding body (31) in the in the <figref idrefs="f0001 f0002 f0003 f0004">Figures 1-7</figref> Embodiments illustrated expands the shape of a spiral, for example an Archimedean spiral, which extends from the light source (20) for secondary optics (80) out. The said light source (20) facing the end face (32) of the fiber-optic element (31) comprises a light entry surface (34) and the secondary optics (80) facing the end face (35) comprises a light exit surface (36). The light entry surface (34) and the light exit surface (36) are the optically utilized areas of the associated end faces (32, 35) and can be less than the end faces (32, 35) to be. The light entry (34) and the light exit surface (36) for example, lie in planes which include for example form an angle of 10 degrees.

p0015The in <figref idrefs="f0001 f0002 f0003 f0004">Figures 1-7</figref> Light-guiding body (31) depicted have a curved guide line (37) which corresponds to the geometric center line of the light guide (31). The Guideline (37) surrounding fiber-optic element (31) has an outer surface line (39). This surface line (39) is the longest surface line of the light guide (31). It is the line which connects in the light propagation direction (5) the points of the peripheral surface (33) with the smallest curvature.

p0016In the illustrated embodiments, the guideline (37) and the surface line (39) are together in one plane. The curvature of the guideline (37) and the curvature of the surface line (39) for example, have a constant focus. Both curves have no point of inflection. Here they take from the light input surface (34) to the light exit surface (36) back from, cf.<figref idrefs="f0001">figures 2</figref> and <figref idrefs="f0003">5</figref>, The light-guiding body (31) but may also be constituted so that the guideline (37) and / or the surface line (39) do not lie in one plane. Thus, the spiral can be constructed as helically. Also, the lines (37, 39) sections have different centers of curvature respectively. Guideline (37) of the optical waveguide (31), instead of the shape of a spiral having the shape of a circular arc section. In this case, the curvature of the guideline (37) is constant.

p0017The light-guiding body (31) may have one or more regions with a straight guideline (37). Such an area bordered then, for example, to the light entry surface (34).

p0018The light entry surface (34) and the light exit surface (36) are arranged in the embodiments normal to the plane in which the guide line (37) is situated. They can also be inclined thereto. The light-guiding body (31) is so constructed such that every straight line through the light entry surface (34) penetrates the lateral surface (33) of the light guide (31) outside the light exit surface (36). There is thus in the light-emitting unit (10) has no light beam passes through the light guide body (31) of the light entry surface (34) to the light exit surface (36), without being on the outer surface (33), the interface (33) of the light guide (31 ), is reflected.

p0019Guideline (37) and the surface line (39) of the optical waveguide (31) sweep in the embodiments an angle of 360 degrees, for example. The from the lines (37, 39) swept angle can also be smaller, such as 180 degrees or 90 degrees. The length L of the surface line (39) in said curved region (38) of the light guide (31) is in this case longer than 2 * ((PI / 2) - alpha) / KI_MaxWhere KI_Max the largest actual curvature of the surface line (39) of the optical waveguide (31). With Alpha the critical angle of total reflection of the material of the light guide (31) against its adjacent area (1) is referred to. In a fiber-optic element (31) made of PMMA, which is surrounded by air, the critical angle is, for example, 42.2 degrees. With these values ​​is at a maximum actual curvature of the circumferential surface (33) of, for example, 8 * 10^-3/ Mm, the surface line (39) of the light guide (31) in the curved portion (38) for more than 208 millimeters. So that everyone at least once totally reflected in the light guide body (31) totally reflected light beam at the curved portion (38) of the optical waveguide (31).

p0020The surface line (39) in the curved portion (38) may be longer than the specified minimum length. Thus, the light guide body (31) may be configured such that a light beam, for example, four or five times reflected. However, increases with the length of the optical path in the light guide body (31), the absorption losses.

p0021The outer surface line (39) in the curved portion (38) their greatest curvature. In the embodiments, the area of ​​maximum curvature to the light entry surface (34) adjoins. There the radius of curvature of the generating line (39) is seven times the diameter of the light entry surface (34). Adjacent to the light outlet surface (36) of the radius of curvature of the generating line is twelve times the diameter of the light entry surface (34).

p0022The minimum allowable radius of curvature of the light guide (31) is determined by the maximum allowable curvature of the longest surface line (39). This maximum allowable curvature is the curvature of the generatrix (39), wherein each in the light entry surface (34) entering light beam in the light guide body (31) at the boundary surfaces (33) of the light guide (31) is totally reflected. If this value is not exceeded, is in the embodiments for the entire light-guiding body (31) satisfies the condition for total reflection.

p0023When using a Lambertian emitter light source (20) results in the maximum curvature K_Max to K_Max = (1 - tan (alpha)) / H In this formula, h is the length of the light entry surface (34) in a plane which this length and the curvature K._Max span. This level is for example perpendicular to the light entry surface (34). The tangent of the angle alpha Totalrelexions limit arises from the refractive indices n₁ of the light guide (31) and n₂ around (1) to tan (alpha) = n₂ / (N₁²-n₂²)^1/2, In cases governed by<figref idrefs="f0001 f0002 f0003 f0004">Figures 1-7</figref> Embodiments shown results with h = 10 mm, n₁ = 1.49 and n₃ = 1 the maximum curvature of the surface line (39) to 9.5 * 10^-3/Millimeter. The minimum required radius of curvature of the surface line (39) amounts to 105 millimeters.

p0024When adopted in the Ausführüngsbeispielen light emitting diode (21) consisting of the light source (20) emitting light beams (90) is theoretically limited by beams (91, 92) at 90 degrees to the normal to the light entry surface (34) auftref fen, see FIG.<figref idrefs="f0004">figure 6</figref>, These light beams (91, 92) are in the present embodiments, when entering the light guide body (31) to the perpendicular to the light entry surface (34) broken out at the impact point, for example at an angle of 42.2 degrees to the normal to the light entry surface (34) , Thus the light from the source (20) light emitted from the light guide body (31) a large part, for example 90%, was added. At the maximum permissible curvature above arrives at the light-guiding body (31) on the outer surface line (39) directed beam of light (91) therein at an angle of 42.2 degrees to the normal at the impingement on and is thus completely at the interface (33) totally reflected.

p0025In a lighting unit (10) having a Lambertian radiator as a light source (20) the ratio of the refractive index of the optical waveguide (31) to the refractive index of the immediate environment (1) of the light guide (31) is greater than die.Wurzel of two to choose. Did the material in the gap (29) and in the remaining area (1) different refractive indices, to the lower refractive index ratio be above this limit. Said limit value of the refractive index ratio is independent of the geometric dimensions of the light entry surface (34).

p0026If the light source (20) has a smaller beam angle than the Lambert radiator, the maximum curvature of the light guide (31) increases. At the same time decreases the ratio between the refractive indices of the optical waveguide (31) and its surroundings (1) minimum required.

p0027The maximum allowable curvature of the generatrix (39), in such a general structure of the light source (20) with a beam angle phi is K_Max = (S - n₂ / n₁) / (H * S), where S = (1 - (n₂/ n₁)² * sin²(Phi / 2))^1/2 is. The ratio of the refractive indices in these cases is greater than or equal to (sin²(Phi / 2) +1)^1/2 to choose the refractive index of the optical waveguide (31) is higher than the refractive index of the environment (1).

p0028With the above refractive indices and said length of the light entrance surface is produced for example at a radiation angle of the light source (20) of 150 degrees, a maximum allowable curvature of the generatrix (39) of 11.8 * 10^-3/Millimeter. With a viewing angle of 120 degrees results in 17.5 * 10^-3/Millimeter. The minimum required ratio of the refractive indices is at a viewing angle of 150 degrees and 1.39 at an angle of 120 degrees 1, 32nd

p0029The maximum angle of the light source (20) in which to enter a maximum of light into the light guide body (31) and can be totally reflected in this, is thus given with a refractive index ratio of eg 1.1 to 54 degrees, at a ratio of 1 , 3 to 112 degrees.

p0030The cross-sectional area of ​​the fiber-optic element (31) takes in the embodiments of the light entry surface (34) to the light exit surface (36) to back. The light-guiding body (31) has along its guideline (37) merging into one another, for example four cross-sectional regions (41-44). A first cross-sectional area (41) adjacent to the light entry surface (34), the fourth cross-sectional area (44) bordering the light outlet surface (36). Also, an embodiment having three or more than four cross-sectional profiles is conceivable.

p0031The light entry surface (34) for example has a shape similar to the main light-emitting surface (24) of the diffuser (23). In the embodiments, both surfaces, eg circular surfaces, wherein the diameter of the light entry surface (34), for example, is greater by 7% than the diameter of the main light-emitting surface (24). The light entry surface (34) but may also be rectangular, oval, elliptical, etc. are formed.

p0032In the first cross-sectional area (41), the cross section of the light guide (31) expands, for example, to an oval cross-sectional area. In the embodiment, the length of the minor axis of this cross-sectional area - this is here normal to the cutting plane of the<figref idrefs="f0003">figure 5</figref> - Greater than or equal to the diameter of the light entry surface (34).

p0033In the second (42) and the third cross-sectional area (43) of the light guide (31) extends the shape of the light guide (31) to another, for example oval cross-sectional profiles.

p0034In the fourth cross-sectional area (44) goes over in the cross-sectional area, the light exit surface (36), for example, has approximately the shape of an oval section. Its width is greater than its height. The lower edge (51) of light outlet surface (36), see FIG.<figref idrefs="f0002">figure 3</figref>, Has two mutually vertically offset portions (52, 53) which are interconnected by means of a connecting portion (54). The sections (52, 53) can - as without a connecting portion (54) - together form an angle of for example 165 degrees or 135 degrees. Here, for example, one of the sections (52; 53) disposed normal to the guide line (37) plane.

p0035The side faces (55) of the fourth cross-sectional area (44) are arranged in mirror image to one another and pass over rounded longitudinal edges in a cover surface (56). The bottom surface (61) of the fourth cross-sectional area (44), see FIG.<figref idrefs="f0002">figure 4</figref>In these embodiments includes two mutually offset curved surface regions (62, 63) which are mounted, for example, cylindrical. The two surface areas (62, 63) are, for example rotated about a common axis to today. The twist angle is in these embodiments, 2 degrees, for example, in the light propagation direction (5) leftmost area (62) further from the fiber-optic element (31) protrudes than the right-most surface area (63). Between the two surface areas (62, 63) is located in these embodiments, a transition region (64). This one is arranged at least approximately centrally along the bottom surface (61). He concludes with the adjacent surface regions (62, 63), for example an angle of 135 degrees. The height of the transition region (64) increases thus in the light propagation direction (5). In cases governed by<figref idrefs="f0002">Figures 3 and 4</figref> Embodiments shown, the height of the transition region (64) at the connecting portion (54) of light outlet surface (36) is 0.5 millimeters.

p0036The center of curvature of facing inner side (47) of the fiber-optic element (31), as shown in the <figref idrefs="f0001 f0002">Figures 1-3</figref> shown, enclose a free space (6). The inside (47) but may also, for example molded or carry fixed supporting elements, such as ribs, spokes or disc-like portions. By means of these supporting elements can, for example the light-guiding (31) are mounted in the headlight. These supports are not considered here as part of the optical waveguide (31).

p0037The primary optics (30) includes, for example the optical waveguide (31) optically downstream primary lens (71), see. <figref idrefs="f0001">figure 2</figref>, This is for example a plano-convex aspheric condenser lens (71), such as a condenser lens. By means of this condensing lens (71) can be selected from the light exit surface (36) emerging light are bundled.

p0038The optical lens can also be formed as an aspherical output surface of the optical waveguide (31). The primary optics (30) then. Between the light-guiding body (31) and the optical lens no interface and no gap The convex surface of the optical lens is in this case part of the light exit surface (36). They can protrude downwardly beyond the lower edge (51). but they may also be designed so that the bottom surface (61) is continued in the lens.

p0039The secondary optics (80) in which in the <figref idrefs="f0001">figure 1</figref> Illustrated embodiment, a secondary lens (81). This is for example a collecting lens large aperture. Herewith a high efficiency of the optical system is achieved.

p0040In the <figref idrefs="f0005">figure 8</figref> is a light-emitting unit shown without the primary lens (71), the secondary lens (81) has the configuration of a Fresnel lens. Such a Fresnel lens (82), see FIG.<figref idrefs="f0001">figure 2</figref>, Allows a small lens thickness at a high aperture. At the same time, such a lens (82) with high process reliability are made of plastic, for example, as is done by the thinness of the lens (82) only a slight shrinkage. In the illustration of<figref idrefs="f0005">figure 8</figref> has the secondary lens (82) in the Fresnelbereichen (83) additional recesses (84). This can be produced specifically, an additional stray light component.

p0041During operation of the lamp unit (10) enters from the light source (20) emitting light beams (90) as described in the light-guiding body (31). In the above-mentioned geometrical conditions the whole, in the light-guiding body (31) entering light bundle (90) is totally reflected at the interface (33) of the light guide (31). However, if the maximum actual curvature of the generating line (39) is greater than the allowable maximum curvature to the light entry surface (34) adjacent outer surface (33) of the fiber-optic element (31) can be at least mirror-coated in the region of the outer surface line (39) to to avoid in this area light exit.

p0042The light beam (90) travels in the light guide body (31) with further total reflection at the interface (33) in the direction of the light exit surface (36), see FIG. <figref idrefs="f0001">figure 2</figref>, Here, the light beam (90) is completely dissolved from the inside (47) of the optical waveguide (31) and is deposited continuously on the on the surface line (39) adjacent area of ​​the interface (33). The angle that enclose the individual light beams with a normal at the point of impact, be greater with increasing distance from the light source (20). The light beam (90) thus clings ever to the outer circumference of the optical waveguide (31).

p0043The course of the individual light beams of the light beam (90) is for example in the <figref idrefs="f0003">figure 5</figref> using two light beams (93) and (94) described. The light beam (93) is totally reflected at the first interface (33) in the region of the inside (47) and then in the outer to the surface line (39) adjacent the region of the fiber-optic element (31). Here, the angle of reflection in the casing of the line (39) adjacent area is smaller than the reflection angle in the region of the inside (47). After four more reflections - the reflection angles increase with increasing distance from the light entry surface (34) - there is no further reflection in the region of the inside (47).

p0044The light beam (94) is first reflected at the sheath of the line (39) comprising the area of ​​the boundary surface (33). And the following reflections take place at the at the surface line (39) comprising the area of ​​the boundary surface (33).

p0045When passing through the fiber-optic element (31) the light beam (90) is formed. So initially formed in the radially outer region of the light guide (31) a light beam of high intensity, see.<figref idrefs="f0001">figure 2</figref>, The product of the angle of the bundle and the used cross-section of the light guide (31) remains constant. The intensity is the guideline (37) and in the inner side (47) decreases.

p0046In the <figref idrefs="f0004">figure 7</figref> is shown adjacent the fourth cross-sectional area (44) a detail of the light exit surface (36). The light bundle (90) is in this range on the bottom surface (61). Here there runs a part of the light beam (90) along said surface area (62), along another part of the surface region (63). The region of the cover surface (56) of the fourth cross-sectional area (44) remains unilluminated.

p0047On the road or on a measuring wall the secondary lens forms (81; 82) in the embodiment of z-shaped lower edge (51) of the light emission surface (36) as sharply formed, z-shaped upper light-dark boundary of the illuminated region from. If the bottom edge with a 15 - degree rise or 45 - degree - formed increases, the illuminated area has a corresponding upper limit. In the vicinity of the lower edge (51) a region of high luminance can be formed on the light exit surface (36) by superposition of light components, the spot formed in the illuminated area of ​​the so-called hot. The luminance at the output of the primary optics (30) can therefore be higher than the luminance of the light source (20). The primary optics (30) of the light unit (10) thus comprises the optical waveguide (31) with variable cross section and curvature, which performs by total reflection, a low-loss deflection, redistribution and concentration of the luminous flux. Here, the arrangement described is largely insensitive to tolerances of the LED radiation or the positioning of the light source (20).

p0048In illuminated region, for example on a measuring wall illumination drops to the side and downwards continuously. It arises as a side and down ill-defined, strip and stain-free illuminated area with an upper sharp, z-shaped light-dark boundary.

p0049The use of such a lamp unit (10) for a basic light distribution is also conceivable.

p0050The light unit (10) described is very efficient due to their geometric configuration and requires only a small installation space. Those with such a light unit (10) can be achieved without additional antireflection coatings absolute outcoupling efficiency is around 80%.

p0051When using RGB LEDs, the individual light components mix as it passes through the light guide, thus resulting in white light at the light exit surface (36).

p0052In one example, coupling of two light-emitting diodes, they can in the first third of the length of the light guide (31), seen from the light incident side (34) of, be coupled. Thus light losses can be avoided.

p0053In the <figref idrefs="f0005">figure 9</figref> is - without light sources - a combined light unit (10) shown for the low beam and the high beam. This corresponds to the light unit (11) for the passing beam in the<figref idrefs="f0001 f0002 f0003 f0004">Figures 1-7</figref> Light unit shown. This is in the<figref idrefs="f0005">figure 9</figref> arranged above. In order to operate the high beam, a below the first light-emitting unit (11) arranged second light-emitting unit (12) is switched on. The two light outlet surfaces (36, 48) of the primary optics (30) are complementary. The lamp unit (10) comprises a secondary lens (82) which receives the light of both light unit parts (11, 12). Such light-emitting unit can be exclusively used for the production of the high beam. In this case, the light outlet surfaces (36, 48) of the primary optics can no joints overlap.

LIST OF REFERENCE NUMBERS

p0054<dl id="dl0002" compact="compact"><dt>1</dt><dd>Surroundings</dd></dl><dl id="dl0003" compact="compact"><dt>5</dt><dd>Light propagation direction</dd><dt>6</dt><dd>blank</dd></dl><dl id="dl0004" compact="compact"><dt>10</dt><dd>light unit</dd><dt>11</dt><dd>Light unit part</dd><dt>12</dt><dd>Light unit part</dd></dl><dl id="dl0005" compact="compact"><dt>20</dt><dd>light source</dd><dt>21</dt><dd>Emitting diode, light emitting diode, LED</dd><dt>22</dt><dd>Light-emitting chip</dd><dt>23</dt><dd>light distribution</dd><dt>24</dt><dd>Main light emission surface</dd></dl><dl id="dl0006" compact="compact"><dt>29</dt><dd>Gap, air gap</dd><dt>30</dt><dd>primary optics</dd><dt>31</dt><dd>light guide body</dd><dt>32</dt><dd>face</dd><dt>33</dt><dd>Shell surface, interface (31)</dd><dt>34</dt><dd>Light entry surface</dd><dt>35</dt><dd>facing end face (80)</dd><dt>36</dt><dd>Light exit surface</dd><dt>37</dt><dd>Guideline</dd><dt>38</dt><dd>curved region</dd><dt>39</dt><dd>Surface line, longest surface line (31)</dd></dl><dl id="dl0007" compact="compact"><dt>41</dt><dd>first cross-sectional area</dd><dt>42</dt><dd>second cross-sectional area</dd><dt>43</dt><dd>third cross-sectional area</dd><dt>44</dt><dd>fourth cross-sectional area </dd><dt>46</dt><dd>Top of (36).</dd><dt>47</dt><dd>inside</dd><dt>48</dt><dd>Light outlet surface of (12)</dd></dl><dl id="dl0008" compact="compact"><dt>51</dt><dd>Lower edge (36)</dd><dt>52</dt><dd>Section of (51)</dd><dt>53</dt><dd>Section of (51)</dd><dt>54</dt><dd>connecting portion</dd><dt>55</dt><dd>side surfaces</dd><dt>56</dt><dd>deck area</dd></dl><dl id="dl0009" compact="compact"><dt>61</dt><dd>floor area</dd><dt>62</dt><dd>Surface section (61)</dd><dt>63</dt><dd>Surface section (61)</dd><dt>64</dt><dd>Transition area</dd></dl><dl id="dl0010" compact="compact"><dt>71</dt><dd>Primary lens, condenser lens, condenser lens</dd></dl><dl id="dl0011" compact="compact"><dt>80</dt><dd>secondary optics</dd><dt>81</dt><dd>secondary lens</dd><dt>82</dt><dd>Fresnel lens, secondary lens</dd><dt>83</dt><dd>Fresnelbereiche</dd><dt>84</dt><dd>cuts</dd></dl><dl id="dl0012" compact="compact"><dt>90</dt><dd>light beam</dd><dt>91-94</dt><dd>light beams</dd></dl>