EP0479042A2 - Lighting device - Google Patents

Abstract

A lighting device having an optical device which decomposes light from a light source into a multiplicity of subbeams and directs the latter onto a surface to be illuminated is specified, a plurality of subbeams being directed onto each subarea of the surface, and it being possible to perceive individual luminous areas (9, 10) at the output of the optical device (7). <??>It is the aim of such a lighting device, on the one hand, to achieve a satisfactory brightness in the surface to be illuminated. On the other hand, dazzling of a person situated at a viewing distance (a) is to be avoided. <??>It is provided for this purpose that the luminous areas (9, 10) do not exceed a maximum size which depends on the viewing distance (a), and that adjacent luminous areas (9, 10) are at a predetermined minimum distance from one another, so that they can be distinguished from one another from the viewing distance (a). <IMAGE>

Description

The invention relates to a lighting arrangement with an optical device which splits light from a light source into a plurality of partial beams and directs them onto a surface to be illuminated, several partial beams being directed onto each partial surface of the surface and individual luminous surfaces being perceptible at the output of the optical device.

Such a lighting arrangement is known from CH 627 252 A. Here, the light beam from a reflector lamp is directed against a reflector arrangement which has a large number of individual reflectors. Each individual reflector is designed so that it illuminates the entire area to be illuminated. The observer of the reflector sees the image of the lamp in each individual reflector, but the light intensity of each image is only a fraction of the light intensity of the lamp corresponding to the number of reflectors. The reduced light intensity that the viewer perceives in each individual image is intended to avoid glare.

Such a lighting arrangement has proven itself in illuminating rooms up to a certain size. A transfer of such a lighting arrangement to larger areas, such as open spaces or larger halls, has so far failed due to the lack of ability of the lighting arrangement to provide enough light for the illumination. At the moment when the light intensity or the luminance of the light source is increased, which is readily possible with modern light sources, the advantageous effect of the reduced light intensity of the image of the light source disappears in the reflector. So there is again a blinding effect.

In the case of lighting tasks, there are basically two distances to be distinguished from the lighting arrangement. First, there is the distance at which the area to be illuminated is located. At this distance, the lighting arrangement must provide enough light to achieve a desired brightness. The brightness can depend on several factors. For example, in a production hall in which production processes to be monitored visually take place, a greater brightness will be required than in a large open space, such as a parking lot or a shipping yard. On the other hand, it should be noted that the eyes of the people who are in the room to be illuminated are not always at the level of the area to be illuminated. This is readily apparent if the surface to be illuminated is the floor, since the eyes of the person are then approximately 1.5 to 2 m closer to the lighting arrangement. However, this question becomes more critical in the case of problems in which the usual or possible location of people is located far above the area to be illuminated, for example when people use movable work platforms or have to be in the driver's cab of a crane arranged above the area to be illuminated. Even when staying in a cab of a truck, the driver's eyes are usually approx. 3 m above the area to be illuminated. There is therefore a viewing distance when solving such lighting tasks to determine, ie a distance at which viewers usually stay. In this case, viewers are people who can deliberately or accidentally look at the lighting arrangement, with the aim of avoiding glare from these viewers.

In lighting technology, efforts are made to protect a viewer who is in the area to be illuminated from glare. At the same time, there should be sufficient brightness in the area to be illuminated. A glare always occurs when parts of the lighting arrangement, such as light source, reflectors or holders, or reflective objects, such as metallic parts, white surfaces or a wet floor covering, appear much brighter to the viewer than the surroundings.

The invention has for its object to provide a lighting arrangement with which a glare can be largely avoided even at high illuminance.

This object is achieved in a lighting arrangement of the type mentioned at the outset in that the luminous areas do not exceed a maximum size dependent on a viewing distance and adjacent luminous areas have a predetermined minimum distance from one another so that they can be distinguished from one another in the viewing distance.

In the arrangement known from CH 627 252 A, it was assumed that, in order to avoid glare, it was sufficient to reduce the light intensity of the image of the light source, that is to say the light intensity of a point or the perceptible luminous area perceptible by the viewer. However, this limits the brightness in the area to be illuminated. It has now been found that the light intensity of each individual point, ie each individual luminous surface, can be increased practically indefinitely, provided that only care is taken that the luminous surfaces do not exceed a predetermined size. This size depends on the viewing distance. The larger the viewing distance, the larger the illuminated area can be selected. The second criterion is that adjacent lighting surfaces must have a predetermined minimum distance from one another. Although the physiological processes of glare have not yet been fully clarified, it is assumed that the reduction in the size of the illuminated area on the retina of the eye of the viewer stimulates only one sensory cell. If the luminous area is larger, several sensory cells are stimulated on the retina. In this case, an unconsciously controlled contrast enhancement sets in that on the one hand inhibits the sensory cells along the cut-off line on the retina and activates it on the other side. At normal ambient luminance levels, this contrast enhancement leads to an increase in visual performance, but at very high luminance levels, there is a feeling of glare. The minimum distance between adjacent illuminated areas is determined by the finite resolution of the human eye. If the distance falls below a certain minimum value, the human eye can no longer distinguish between the two illuminated areas. The two luminous areas then each stimulate only a single sensory cell on the retina, but the two sensory cells are adjacent, so that the contrast enhancement described above takes place again. The minimum distance between two illuminated areas also depends on the distance between the viewers. It can be smaller with a small viewing distance than with a large viewing distance.

In a preferred embodiment, the maximum size of the luminous area is selected as a function of a luminous means used in the light source. It is assumed that the perception of glare is influenced, among other things, by the color of the light, which is determined by the illuminant used in the light source.

wobei a der Betrachtungsabstand in m ist und x in Winkelminuten durch folgende Beziehung definiert ist:

$\text{x = (-1/g · ln ((K - B) / (K - 1)) - s,}$

wobei

$\text{0,5 ≦ g ≦ 0,9}$

$\text{6 ≦ K ≦ 9}$

$\text{1 ≦ B ≦ 6}$

und

$\text{0 ≦ s ≦ 0,3.}$

In a preferred embodiment, an exact definition results from the fact that each luminous area has a maximum dimension D, which is defined by the following relationship:

$\text{D = 2aatan (x / 2),}$

where a is the viewing distance in m and x in angular minutes is defined by the following relationship:

$\text{x = (-1 / g · ln ((K - B) / (K - 1)) - s,}$

in which

$\text{0.5 ≦ g ≦ 0.9}$

$\text{6 ≦ K ≦ 9}$

$\text{1 ≦ B ≦ 6}$

and

$\text{0 ≦ s ≦ 0.3.}$

The sizes g, K and s depend on the illuminant used. For example, for halogen g is in the order of 0.5 to 0.7, K in the order of 8 to 9 and s in the order of 0.01 to 0.03. For high-pressure sodium vapor as the illuminant, K is smaller and s larger, for high-pressure mercury vapor as the illuminant, g is larger, K smaller and s smaller than for halogen. Exact values for the individual illuminants can easily be determined, for example, by simple tests in which the glare effect is determined for different test subjects.

It is preferred that B is selected as a function of the sensation of glare that is reasonable in the viewing distance. The smaller B is chosen, the lower the subjective feeling of glare. With B = 1 the glare is imperceptible, with B = 6 it is at the upper limit of what is tolerable, but without the glare being unreasonable.

The feeling of glare is a subjectively assessable variable. It depends on a number of factors, including the age and general condition of the viewer. Fatigue and alcohol consumption, for example, increase the feeling of being blinded under otherwise unchanged conditions. With B = 6, a part of a larger group of viewers may well feel a slight glare, especially if this group also includes older people or it can be expected that the viewers are usually tired if they use the lighting arrangement consider. In this case you will choose a glare index of B = 5 or less. At B = 4, practically no observer will speak of glare.

wobei a der Betrachtungsabstand in m und y 10 Winkelminuten ist. Bei dieser Dimensionierung ist sichergestellt, daß benachbarte Leuchtflächen für den Betrachter unterscheidbar sind.The minimum distance b between adjacent luminous surfaces is preferably defined by the relationship

$\text{b = 2aatan (y / 2),}$

where a is the viewing distance in m and y is 10 angular minutes. This dimensioning ensures that neighboring light surfaces can be distinguished by the viewer.

In a preferred embodiment, the optical device has a reflector arrangement with a multiplicity of adjustable reflectors. The number of reflectors can be several hundred. This ensures that a large number of non-glare Luminous surfaces can be generated, which nevertheless produce sufficient brightness in the surface to be illuminated. The adjustability of the reflectors provides a high degree of flexibility, so that the same reflector arrangement can be used for a large number of lighting tasks. In addition, the manufacture of the reflector arrangement is simpler, since the distance between adjacent luminous surfaces can be set at the place of installation. There is no need for complex alignments of a large number of reflectors during production.

It is preferred that the reflectors are adjustable in groups. The distance between individual luminous areas can still be set for smaller groups with reasonable effort in that the reflectors of a group have a predetermined orientation to one another. The adjustment in groups at the installation site is then simplified by the group-wise adjustment.

It is preferred that a group of collectively adjustable reflectors is arranged on a common carrier, a plurality of carriers being arranged in a frame and each carrier being adjustable in the frame. A basic setting can be achieved by aligning the frame, for example in such a way that the light from the light source is directed onto the surface to be illuminated. The individual luminous surfaces are then adjusted by adjusting the individual supports in the frame, as a result of which the individual groups of reflectors are adjusted.

It is advantageous that the carrier can be pivoted in two directions in the frame. This allows the reflectors to be adjusted so that the surface to be illuminated can be illuminated evenly or with a focus, as desired.

It is preferred that the pivot axes run essentially in the middle of the carrier. As a result, the reflectors remain essentially the same distance from the light source even after pivoting. It is practically not necessary to compensate for the different distances of individual reflectors to the light source caused by the inclination by other measures.

A carrier advantageously has four to eight reflectors. A group with four to eight reflectors can be constructed relatively easily so that a viewer can clearly distinguish between adjacent light surfaces. This is also possible with larger reflector groups, but in any case involves a higher construction effort.

In a preferred embodiment, the reflectors are dome-shaped. Here, an observer perceives the virtual reflection of the light source on each dome as a luminous surface. The luminous surface on the reflector is greatly reduced compared to the luminous surface of the light source. This measure enables relatively small luminous area sizes and relatively large luminous area spacings to be achieved.

In a particularly preferred embodiment, the light source has a plurality of emitters. The spotlights throw their light in only one direction. If this direction does not aim at the surface to be illuminated, i.e. does not hit a viewer at a distance from the viewing area, there is no risk of glare from direct radiation. The plurality of spotlights also generates a plurality of light areas on the reflector arrangement. Each light surface contributes to increasing the brightness of the surface to be illuminated. However, the individual light areas can be kept small enough to avoid glare.

It is preferred that the radiators are spaced from each other. The distance that the radiators have from one another is found on the reflector arrangement. The virtual mirror images of the individual radiators then have the desired minimum distance from one another.

In another preferred embodiment, the optical device has a lens arrangement. The division of the light beam from the light source into several individual light surfaces can be achieved not only with reflectors, but also with a suitable arrangement of lenses which, as required, scatter or bundle the light.

It is preferred that the lens arrangement has individual lenses, the optical axes of which can be adjusted individually or in groups. Here, too, it can advantageously be achieved that a large number of lighting tasks can be solved with relatively little development and production expenditure.

The light source advantageously has a luminance of more than 100,000 cd / m². With luminances that begin in this order of magnitude, a relatively high brightness can be achieved in the area to be illuminated. The luminance can be increased practically indefinitely. Tests have shown that even at a luminance of 15,000,000 cd / m² there is no significant or unpleasant glare.

Fig. 1

eine erste Ausführungsform einer Beleuchtungsanordnung,

Fig. 2

ein Schema zur Erläuterung der Leuchtflächengröße,

Fig. 3

ein Schema zur Erläuterung des Leuchtflächenabstandes,

Fig. 4

eine Reflektoranordnung,

Fig. 5

einen Ausschnitt aus der Reflektoranordnung nach Fig. 4,

Fig. 6

einen Schnitt 6-6 nach Fig. 5,

Fig. 7

einen Schnitt 7-7 nach Fig. 5 und

Fig. 8

eine weitere Beleuchtungsanordnung.

The invention is described below on the basis of preferred exemplary embodiments in conjunction with the drawing. In it show:

Fig. 1

a first embodiment of a lighting arrangement,

Fig. 2

a diagram to explain the size of the illuminated area,

Fig. 3

a diagram for explaining the luminous area distance,

Fig. 4

a reflector arrangement,

Fig. 5

4 shows a section of the reflector arrangement according to FIG. 4,

Fig. 6

a section 6-6 of FIG. 5,

Fig. 7

a section 7-7 of FIG. 5 and

Fig. 8

another lighting arrangement.

A lighting arrangement 1 has a light source 2 which is attached to a mast 3. The light source 2 has a large number of radiators 4, three of which are shown schematically. The radiators are arranged on a platform 5. In this case, the light beams 6 generated by them are directed vertically upwards, i.e. roughly parallel to the mast. A reflector arrangement 7 is attached to the mast above the platform 5. The reflector arrangement is so large that it completely catches the light beams 6 emitted by the light source 2. At most, the emitters 4 on the edge of the platform 5 can guide a very small part of their light beam 6 past the reflector arrangement 7.

The reflector arrangement has a multiplicity of individual reflectors 8 which are dome-shaped. Sixteen individual reflectors are shown, which are arranged in an arrangement of four by four. In reality, the reflector arrangement has several hundred, for example 400, individual reflectors. Due to the spherical shape of the individual reflector, the virtual mirror image of the emitters 4 on the individual reflector 8 is reduced. An observer at a viewing distance a perceives the virtual mirror image as a luminous surface. Since the viewer sees several individual reflectors 8 at the same time, he perceives a corresponding number of luminous areas 9, 10. However, this also means that a large number of light beams are directed at the point at which the viewer is located, so that there is sufficient brightness at this point or on the surface to be illuminated.

The individual reflectors 8 are designed such that the luminous areas 9, 10 do not exceed a predetermined size. Each luminous area 9, 10 is limited by its largest dimension D. The largest dimension D is the largest dimension of the illuminated area. In the simplest case of a circular illuminated area, the largest dimension D corresponds to the diameter of the illuminated area. The largest dimension D is now determined as a function of the viewing distance a by the following relationship:

$\text{D = 2 · a · tan (x / 2).}$

Here a is the viewing distance in m, x in the dimension arc minutes results in

$\text{x = (-1 / g · ln (K - B) / (K - 1)) - s.}$

$\text{6 ≦ K ≦ 9}$

$\text{1 ≦ B ≦ 6}$

$\text{0 ≦ s ≦ 0,3.}$

The sizes g, K and s are dependent on the illuminant used in the light source 2. In general it can be said that

$\text{0.5 ≦ g ≦ 0.9}$

$\text{6 ≦ K ≦ 9}$

$\text{1 ≦ B ≦ 6}$

$\text{0 ≦ s ≦ 0.3.}$

The value B is chosen as a function of the subjective glare of an observer at the viewing distance a. For example, the value B = 1 corresponds to an imperceptible glare, while B = 6 is at the upper limit of the tolerable. The choice of factor B depends, among other things, on safety requirements. For cases in which a sensation of light at the upper limit of what is reasonable would endanger, the factor B must be in the range of 1 to 4. In other cases, where a light that is perceived as extremely bright for the viewer is still permissible, but which does not yet lead directly to glare, B can also have the value 6. As a precaution, one will choose the value B = 5 if it is to be expected that individual viewers will react more sensitively. It should be pointed out that even with a value of B = 6, glare is not yet unreasonable for the viewer.

The factors g, K and s depend on the illuminant used. For example, the values g = 0.58, K = 8.42 and s = 0.02 were determined for a halogen lamp as the illuminant. For high pressure sodium vapor, the value for K is smaller, for s larger. The value for g is higher for high pressure mercury vapor. For K it lies between the values for halogen and high pressure sodium vapor. The value for s is smaller than the value for the first two lamps.

wobei a der Betrachtungsabstand in m und y größer oder gleich 10 Bogenminuten ist.The size of the illuminated area is selected so that the viewer perceives a large number of very brightly illuminated areas, but perceives them as sparkling. When viewed, the reflector looks like a very clear night sky, on which the star density is very high. However, the size of the illuminated area is not the only criterion for freedom from glare. The distance from adjacent luminous surfaces must also be chosen so that the eye of the beholder sees the neighboring luminous surfaces can still differentiate and does not contract into a single illuminated area. To ensure distinctness, the viewing distance can be defined using the following relationship, for example:

$\text{b = 2aatan (y / 2),}$

where a is the viewing distance in m and y greater than or equal to 10 arc minutes.

Fig. 3 illustrates this relationship. A viewer located at viewing distance a, that is to say a viewer who is in a viewing plane 11, can distinguish two adjacent illuminated surfaces 9, 10 if the solid angle y is greater than 10 arc minutes.

2 and 3 that the luminous areas 9, 10 can be larger the larger the viewing distance a. On the other hand, however, the distance b between adjacent luminous surfaces 9, 10 must also become larger as the viewing distance a increases.

The light source has a luminance of more than 100,000 cd / m². The light density can also assume values of 15,000,000 cd / m². In this case, the viewer perceives very brightly illuminated areas. Despite the high light intensity of these luminous areas, the luminous areas do not lead to glare as long as the predetermined maximum luminous area size is not exceeded and the minimum luminous area distance is not exceeded.

Glare can also occur with indirect glare, for example on wet floors, through metal or glass parts or through light surfaces such as paper or markings. At most, the viewer can use these reflecting surfaces to create a mirror image of the reflector arrangement with a large number of brightly glowing dots after the reflection having the same distance from one another generated in the reflector arrangement, glare is not to be feared here. This makes the lighting arrangement suitable for a large number of uses, for example also on the apron of train stations, where there is otherwise the risk of indirect glare due to reflection on the tracks due to the metallic tracks. It can also be used on large open spaces, which are also highly reflective when wet. Indirect glare from wet ground, for example wet asphalt, is just as impossible as direct glare from viewing the reflector arrangement 7. The size of the luminous surfaces 9, 10 can be determined on the one hand by the dome shape, but on the other hand by the distance of the spotlights 4 from the Influence reflector arrangement 7. The further the radiators 4 are from the reflector arrangement 7, the smaller the virtual mirror images of the radiators 4 on the individual reflectors 8. A limiting factor here is that the radiators must not be arranged so deep that an observer accidentally looks directly into them can. A glare effect can, however, be avoided by suitable shielding measures or by largely aligning the light beams 6 from the beams 4. In this way it is possible to achieve high luminance levels without having to use high masts to illuminate the area to be illuminated. High masts cannot be used in some areas, for example in buildings or in tunnels or on the apron of an airport.

4 shows a reflector arrangement 7 with 64 individual reflectors 8. This illustration is also only schematic. As stated above, the reflector arrangement 7 has several hundred individual reflectors 8. The individual reflectors 8 are in groups of four individual reflectors summarized. Each group is arranged on a carrier 12. The carriers 12 are in turn arranged in a frame 13 which is attached to the mast 3.

Each carrier 12 is rotatably supported in a subframe with the help of pivots. The pivots 15 are arranged essentially in the middle of the carrier. In the exemplary embodiment shown, each carrier 12 can be pivoted about a vertical axis relative to the auxiliary frame 14. The subframe 14 has horizontally arranged pivot pins 16 about which the subframe 14 can be pivoted in the frame 13. The pivots 16 form an axis which likewise runs essentially in the center of the carrier 12 and intersects the axis formed by the pivots 15 at an angle of approximately 90 °. The carrier 12 can thus be pivoted relative to the frame 13 in two different directions. Because the pivot axes run approximately in the center of the carrier, the distance from the light source 2 changes only slightly when the carrier 12 is pivoted. The change in distance is so small that measures to compensate for a possible error can be practically omitted.

The individual reflectors 8 on a carrier 12 can be of identical design. Likewise, all supports can have the same reflectors. During production, it is only necessary to ensure that the four virtual mirror images of the light source 2, that is to say the four luminous surfaces which arise on the four individual reflectors 8, do not exceed the maximum size and do not fall below the minimum distance. The further adjustment, ie the alignment of the other reflectors 8, which are not arranged on the same support 12, can take place as soon as the reflector arrangement 7 is installed on the mast. For example, the reflector arrangement 7 can then be oriented such that an observer located at one point can only perceive illuminated surfaces 9, 10 on every second or third carrier 12.

However, the lighting arrangement can be realized not only with the aid of reflectors as optical devices that reflect the light back, but also with a lens arrangement that let the light through from a light source 102 and thereby scatter it. Such an arrangement is shown schematically in FIG. 8. The light source 102 illuminates a first lens 40 which scatters the received light and forwards it to lenses 41, 42, 43 of a second lens plane. The lenses 41 to 43 of the second lens plane in turn scatter the received light and pass it on to lenses 44, 45, 46, 47 of a third lens plane. For the sake of clarity, the lenses 40 to 47 are connected to one another only by a single light beam. In reality, of course, it is not a point beam, but a beam with a finite spatial extension. The person skilled in the art can easily determine the shape of the lenses 40 to 47 if he takes into account that at the output of the lenses 44 to 47 only those luminous areas may be created which do not exceed a predetermined size but maintain a predetermined minimum distance from one another. Additional lens planes can also be used.

To simplify the adjustability, it can be provided that the optical axes of the lenses can be adjusted individually or in groups. For example, the lenses 44, 45 or 46 and 47 can be adjusted together. Such an arrangement with diffusing and / or converging lenses is always appropriate if the light source in a reflector arrangement would have to be arranged in an area that is required by the viewer. In this case, the light source 102 can be arranged above the lens arrangement 40 to 47. There is no danger of a very hot or directly blinding light source in the danger area.

Claims (18)

Lighting arrangement with an optical device which splits light from a light source into a plurality of partial beams and directs them onto a surface to be illuminated, several partial beams being directed onto each partial surface of the surface and individual luminous surfaces being perceptible at the output of the optical device, characterized in that the luminous areas (9, 10) do not exceed a maximum size (D) dependent on a viewing distance (a) and adjacent luminous areas (9, 10) are at a predetermined minimum distance (b) from one another, so that they can be distinguished in the viewing distance (a). Lighting arrangement according to claim 1, characterized in that the maximum size (D) of the luminous surfaces (9, 10) is selected as a function of a luminous means used in the light source (2, 102). Lighting arrangement according to claim 1 or 2, characterized in that each luminous surface has a maximum dimension (D) which is defined by the following relationship:

$\text{D = 2aatan (x / 2),}$

where a is the viewing distance in m and

$\text{x = (-1 / g · ln ((K - B) / (K - 1)) - s}$

where x is given in arc minutes and

$\text{0.5 ≦ g ≦ 0.9}$

$\text{6 ≦ K ≦ 9}$

$\text{1 ≦ B ≦ 6}$

$\text{0 ≦ s ≦ 0.3.}$

Lighting arrangement according to claim 3, characterized in that B is selected as a function of the sensation of glare which is reasonable in the viewing distance (a). Lighting arrangement according to claim 4, characterized in that B ≦ 5, in particular B ≦ 4. Lighting arrangement according to one of claims 1 to - 5, characterized in that the minimum distance (b) between adjacent luminous surfaces (9, 10) is defined by the relationship:

$\text{b = 2aatan (y / 2),}$

where a is the viewing distance in m and y ≧ 10 arc minutes. Lighting arrangement according to one of claims 1 to 6, characterized in that the optical device has a reflector arrangement (7) with a plurality of adjustable reflectors (8). Lighting arrangement according to claim 7, characterized in that the reflectors (8) are adjustable in groups. Lighting arrangement according to claim 8, characterized in that a group of collectively adjustable reflectors (8) are arranged on a common carrier (12), a plurality of carriers (12) being arranged in a frame (13) and each carrier (12) is adjustable in the frame (13). Lighting arrangement according to claim 9, characterized in that the supports (12) in the frame (13) can be pivoted in two directions. Lighting arrangement according to claim 10, characterized in that the pivot axes (15, 16) run essentially in the middle of the carrier (12). Lighting arrangement according to one of claims 9 to 11, characterized in that a carrier (12) has four to eight reflectors (8). Lighting arrangement according to one of claims 7 to 12, characterized in that the reflectors (8) are dome-shaped. Lighting arrangement according to one of claims 1 to 13, characterized in that the light source (2) has a plurality of spotlights (4). Lighting arrangement according to claim 14, characterized in that the radiators (4) are arranged at a distance from one another. Lighting arrangement according to one of claims 1 to 15, characterized in that the optical device has a lens arrangement (40-47). Lighting arrangement according to claim 16, characterized in that the lens arrangement has individual lenses (40-47), the optical axes of which can be adjusted individually or in groups. Lighting arrangement according to one of claims 1 to 17, characterized in that the light source (2, 102) has a luminance of more than 100,000 cd / m².

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