EP0413088B1 - Work lamp - Google Patents

Abstract

Work lamps such as those which are preferably employed in office system work places put high demands on a uniform illumination of the working surface without dazzling the user in the process. As shown in practice, the necessary screening of the fluorescent lamp arrangement leads to disturbing reflected images, particularly given a low lamp installation height. It is proposed to provide the fluorescent lamp arrangement (LL), which is located here at the rear side of the housing trough (G), with a flat main reflector (R1), which is inclined forwards and reaches as far as the front edge of the housing trough (G), and with an auxiliary reflector (R2) below and in front of the fluorescent lamp arrangement (LL), which makes it impossible to see into the fluorescent lamp arrangement (G). The light exit opening is covered in this arrangement by a diffusing panel which has a fine prismatic structure on the lamp side. <IMAGE>

Description

The invention relates to a workplace lamp according to the preamble of claim 1.

Workplace lights of this type, for example from DE 26 30 556 A1, have the task of compensating for strong shadows from daylight and general lighting. Such workplace lights are of particular importance in "office system workplaces" in open-plan offices that have been common for several years, in which the individual spaces are separated by partitions and are often provided with cupboard attachments above the rear part of the work surface.

The lighting technology requirements placed on such workplace luminaires are by no means limited to a uniform distribution of illuminance on the work surface. Rather, the Avoidance of structured light reflections.

As can be seen, the shielding of the fluorescent lamp arrangement on shiny visual objects causes structured reflex images, which make the visual task much more difficult (interference information) than unstructured, informationless reflexes. Furthermore, it is shown with such workplace lamps that the illuminance in the rear part of the work surface is significantly higher than in the front work area, which usually contains the work task. This draws attention away from the task at hand. In addition, in the case of such workplace lamps, as long as a vertical partition is provided on the rear of the work table, inappropriately high luminance levels occur. This can cause distracting reflections on the work item or on display devices placed opposite the rear wall. It is not possible to use such workplace lights without the partition mentioned, because otherwise severe glare will occur in people whose workplace is on the opposite side.

The invention has for its object to provide a solution for a workplace lamp of the type described in the introduction, which largely avoids structured reflections on the work item on the one hand and furthermore reduces undesirable high illuminance levels in the rear part of the work surface to such an extent that the use of such workplace lamps also with Double workplaces with people sitting opposite each other is possible without a vertical partition in between.

This object is achieved according to the invention by the features specified in claim 1.

Due to the special design and arrangement of main and With a good shielding of the fluorescent lamp arrangement, auxiliary reflector, in addition to uniform illumination of the work table in its longitudinal extension, also prevents the undesired increased luminance on the back of the work table and, in addition, a reduction in structured reflection images is achieved by directing the light directed onto the diffusing screen.

The auxiliary reflector that shields the fluorescent lamp arrangement can be used according to claim 2 in an extremely advantageous manner by selecting its width projected onto the horizontal to determine the luminance at the rear of the work table.

In order to optimize the reduction of the undesired structured reflex images on the work table surface by means of light control via the diffusing screen, it is proposed according to an advantageous further development of the invention to divide the diffusing screen into a front, wide strip area and a rear, narrow strip area and at least the front strip area to be designed as a prism plate with mutually parallel prisms in fine structure on the light incidence side, with prisms running perpendicular to the longitudinal extension of the work table. The width of the rear stripe area is chosen so that the transition between the two stripe areas is shielded by the auxiliary reflector or its angled foot against the light directly incident on the lens.

Additional preferred embodiments of the subject matter of the invention are specified in the further claims 4 to 17.

Fig. 1

die Seitenansicht eines Bürosystem-Arbeitsplatzes mit rückseitiger Trennwand und Schrankaufsatz, bei dem die Arbeitsplatzleuchte in die Unterseite des Schrankaufsatzes eingebaut ist,

Fig. 2

eine Aufsicht auf die Tischfläche des Arbeitsplatzes nach Fig. 1 mit Bereichen üblicher, durch die Abschirmung der Leuchtstofflampenanordnung der Arbeitsplatzleuchte bedingter strukturierter Reflexbilder,

Fig. 3

eine schematische Explosionsdarstellung der erfindungsgemäßen Arbeitsplatzleuchte,

Fig. 4

eine Querschnittsdarstellung der Arbeitsplatzleuchte nach Fig. 3,

Fig. 5

eine Aufsicht und eine Seitenansicht, der die Gehäusewanne der Arbeitsplatzleuchte nach den Figuren 3 und 4 abschließenden Streuscheibe,

Fig. 6

ein Ausschnitt aus einer 45°-Prismenrasterfolie, wie sie bei einer Streuscheibe nach Fig. 5 zur Anwendung kommt,

Fig. 7 und 8

die Lichtlenkung und ihre Auswirkung auf die Herabsetzung von strukturierten Reflexbildern auf der Arbeitstischfläche erläuternde schematische Darstellungen,

Fig. 9 und 10

weitere bevorzugte Gestaltungen der Streischeibe.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawing, in which:

Fig. 1

the side view of an office system workstation with a partition on the back and a cabinet attachment, in which the workstation lamp is built into the underside of the cabinet attachment,

Fig. 2

1 with areas of conventional structured reflection images caused by the shielding of the fluorescent lamp arrangement of the workplace lamp,

Fig. 3

2 shows a schematic exploded view of the workplace lamp according to the invention,

Fig. 4

3 shows a cross-sectional illustration of the workplace lamp according to FIG. 3,

Fig. 5

2 shows a top view and a side view of the diffusing screen that closes the housing trough of the workplace lamp according to FIGS. 3 and 4,

Fig. 6

5 shows a section of a 45 ° prismatic grid film, as is used in a diffusing screen according to FIG. 5,

7 and 8

the schematic control of light and its effect on the reduction of structured reflex images on the work surface,

9 and 10

further preferred designs of the striking disc.

The work station AZ, shown in FIG. 1 as an office system work station in a side view, has a work table AT with a table height th = 730 mm, on the back of which a vertical partition TW with an add-on cupboard AS in a cupboard height sh = 500 mm above Work surface AF is provided. The approximate eye position AP of the user of this work station AZ is at an eye height ah = 400 mm above the work surface AF. The workplace lamp L with the fluorescent lamp arrangement LL, which is indicated in broken lines in FIG. 1, is built into the underside of the top cabinet AS.

The light LI of the workplace lamp L that is incident on the work surface AF, as is usually perceived at the predetermined eye position AP of the user, divides the work surface AF of the work table AT into three successive zones in the user's direction of view, namely a zone of low light reflection intensity Z1 in the rear area of the work table AT, a zone of high light reflection intensity Z2, which adjoins this rear zone and a third zone without light reflections Z3 on the front of the work surface AF. These zones are shown in the plan view of the work surface AF shown in FIG. 2 with a usual width bt = 800 mm and a usual length lt = 1600 mm of such a work table AT. The zone of low light reflection intensity Z1 has a width of bz1 = 450 mm, the zone of high light reflection intensity Z2 a width of bz2 = 150 mm and the zone without light reflections Z3 a width of bz3 = 200 mm. The different intensity of the light reflections is indicated in Fig. 2 by larger and smaller nested circles.

As has already been stated, these usual intensities of the light reflections on the work surface AF result from the indispensable shielding of the fluorescent lamp arrangement LL of the work station lamp L. In FIG. 2 it is assumed that the work station lamp L extends over the entire length lt of the work table AT and that here the fluorescent lamp arrangement LL in the workplace lamp L is approximately adapted to this length.

The conventional reflection lamps of this type in addition to the structured reflection images on the work surface AF shown in FIG. 2 and the much too high luminance in the rear area of the work table AT and the partition wall TW can be largely determined by the inventive workplace lamp shown in an exemplary embodiment in FIG. 3 reduce or eliminate.

The workplace lamp L according to FIG. 3 consists of a housing trough G with a rear side wall G1 and a front side wall G2 in the viewing direction of the workplace user. The housing trough G is closed by a diffuser SS, which is fastened to the housing trough G in a light-tight manner at its edges. The fluorescent lamp arrangement LL, which extends practically over the entire length of the housing trough G, which in the simplest case is a single fluorescent lamp of corresponding length, is arranged in the vicinity of the rear side wall G1. In front of the fluorescent lamp arrangement LL, a planar main reflector R1 extending over the entire length of the housing wall is provided. 3 in FIG. 4, the main reflector R1 extends forward to the front side wall G2 of the housing trough G and is inclined towards this front side wall at a small angle α to the horizontal. With its rear edge R11 running parallel to the fluorescent lamp arrangement LL above the fluorescent lamp arrangement LL, the main reflector R1 ends at a distance b shown in FIG. 4 in front of the fluorescent lamp arrangement LL, which is chosen such that the far larger proportion of the light LI at the main reflector R1 is less than one Angle γ> 30 ° to the vertical against the lens SS is deflected.

As FIGS. 3 and 4 also show, in addition to the main reflector R1, the workplace lamp L also has an auxiliary reflector R2, which also extends over the entire length of the housing trough G and is arranged here directly above the diffusing screen SS in front of and below the fluorescent lamp arrangement LL. The auxiliary reflector R2 has a width e projected onto the horizontal and is also inclined toward the lens SS at a small angle β. On the part of the fluorescent lamp arrangement LL, the auxiliary reflector R2 merges into an angled base R22 which extends rearward to below the fluorescent lamp arrangement LL and serves primarily to shield the lamp light which falls directly onto the lens SS from above. The width c of the angle foot R22, and the mentioned width e of the auxiliary reflector R2 are dimensioned so that the desired light distribution between the front and rear part of the work table is achieved. As can also be seen in FIG. 3, the main reflector R1 and auxiliary reflector R2 are delimited on both sides at right angles by triangular or trapezoidal end reflectors R3 which are in themselves flat. The front reflectors R3 extend rearward beyond the rear edge R11 of the main reflector R1.

This design of the overall reflector arrangement, as shown in FIG. 4, has the effect that the major part of the light LI emitted by the fluorescent lamp arrangement LL is deflected at a relatively large angle γ to the vertical at the main reflector R1 against the lens SS, as a result of which the desired uniform and Low-reflection illumination of the working surface AF of the work table AT is favored. By a suitable choice of the angle α within the limits of 10 ° ≦ α ≦ 20 °, the ratio of the light emitted at a large angle γ to the vertical downwards through the diffusing screen SS to the light emitted at a small angle to the vertical can be adapted to different lighting requirements within certain limits will. In the same way, the angle of the inclination of the auxiliary reflector R2 against the horizontal can be selected within certain limits, preferably within the limits 5 ° ° β ≦ 15 °.

The main reflector R1, the auxiliary reflector R2 and the front reflectors R3 are usually made of anodized aluminum sheet. The auxiliary reflector R2 expediently has a high-gloss mirror surface. As the light LI shown in the form of rays in FIG. 4 shows, the auxiliary reflector R2 not only shields the fluorescent lamp arrangement when the user is in the normal eye position AP, but also amplifies the light by means of a double reflection of the light at the auxiliary reflector R2 and at the main reflector R1 at a large angle γ to the vertical emitted light component.

In a first exemplary embodiment, a diffusing screen SS with the width g is shown in plan view and side view in FIG. 5. The lens SS is designed as a prism plate with parallel prisms in fine structure on the light incidence side and also divided into the front of the housing pan G into a wide front strip area SB1 with prisms perpendicular to the longitudinal extension of the work table AT and a narrow rear strip area SB2. In this first exemplary embodiment, the rear narrow strip area SB2 is designed with parallel prisms in fine structure on the light incidence side, which, when the work table AT extends, has a width bt at an angle δ within the limits of 20 ° ≦ δ ≦ 40 ° and a mirror image of the center line M. of the narrow strip area SB2, again divided in its length in the middle, run. The width f of the narrow stripe area SB2 is chosen so large that the transition between the two stripe areas SB1 and SB2 is shielded by the auxiliary reflector R2 or its angled base R22 against the light LI of the fluorescent lamp arrangement LL which is directly incident on the diffusing screen SS.

As the side view of the diffusion plate SS also shown in FIG. 5 indicates, it can consist of a carrier plate TP made of clear glass or a clear synthetic glass, for example acrylic glass, to which a commercially available prism film PF with the desired fine prism structure is adhered.

The fine prism structure preferably consists of a 45 ° prism grid P, which is shown in the detail in FIG. 6. The fine structure of the 45 ° prism grid P has a grid width RB of 0.35 mm and a grid depth RT of 0.17 mm. Such a prism sheet is commercially available under the name 3M Scotch Optical Lighting Film.

The design of the course of the 45 ° prism grid P of the rear narrow strip area SB2 at the angle δ to the center line M gives the user a view of the fluorescent lamp arrangement arranged directly above this narrow strip area SB2 denied and at the same time largely prevented the formation of structured reflex images in the zone designated Z1 in FIG. 2.

The reduction in reflex achieved by the alignment of the 45 ° prism grid P in the wide strip region SB1 is explained in more detail in the illustrations in FIGS. 7 and 8. The light LI emanating from the fluorescent lamp arrangement LL is directed in the direction transverse to the viewing direction of the user as it passes through the diffusing screen SS and, in the extension of the work table AT on the working surface AF, leads to a central shielding area AB which is delimited on both sides by bright areas HB. In the shielding area AB, the diffusing screen SS has a transmittance of less than 10% and the light exit opening of the lamp appears in an almost structureless dark gray. Accordingly, the reflection image of the shielded area has no structure and its luminance is a factor of 1:80 below the luminance of the fluorescent lamp arrangement. In this way it is achieved that the reflection image is barely perceptible even on high-gloss materials under normal ambient conditions.

In the case of a work station AZ, as indicated as an exemplary embodiment in FIG. 1, a shielding area AB of a trapezoidal shape is obtained for the user's gaze direction according to the eye position AP, as seen from the top of the work surface AF according to FIG low reflective luminance about the width of a DIN A4 page. According to FIG. 2, as shown in FIG. 8, for the zone of low light reflection intensity Z1, the zone of high light reflection intensity Z2 and the zone without light reflections Z3, luminances in the shielding area AB and in the zone Z1 are approximately 1:80 and in the bright areas HB the zone Z2 luminance of 1:20 compared to the luminance of the fluorescent lamp arrangement LL.

If the given direction of view is approximately maintained, the eye position AP can be changed as desired in the longitudinal direction of the working surface AF without the lighting conditions changing for the user because the low-reflection shielding area AB moves along.

As can also be seen in FIG. 7, the shielding area AB is illuminated without reflection by the light emerging laterally from the unshielded areas of the diffusing screen SS. The bright areas HB on both sides of the shielding area AB still have a reflection image, but due to the properties of the main reflector R1 and auxiliary reflector R2, the reflection image that occurs is unstructured and its luminance is, as indicated in FIG. 8, by at least a factor of 1 : 20 below the luminance of the fluorescent lamp arrangement LL, so that this results in only a slight complication of the visual task.

In the further preferred exemplary embodiments for spreading disks in sandwich form shown in FIGS. 9 and 10, the prism film PF described in connection with FIG. 5 is clamped practically without adhesive between a clear glass plate representing the carrier plate TP and a cover TAP, likewise in the form of a clear glass plate. The clear glass plates are expediently plastic plates, for example made of acrylic glass or polycarbonate.

According to FIG. 5, the spreading disc SS is also subdivided in its extension into a front wide strip area SB1 and a rear narrow strip area SB2. In contrast to the embodiment according to FIG. 5, however, the rear narrow strip area SB2 on the light incidence side of the carrier plate TP is not designed with prisms that are parallel to one another and has a fine structure, but instead has a lacquer layer or a plastic film cover with a light transmittance of 5 to 10%.

The auxiliary reflector R2 is attached to the top of the cover TAP by means of adhesive and in such a way that the joint between the front wide strip area SB1 and the rear narrow strip area SB2 lies below the auxiliary reflector R2.

As can be seen from the embodiment of the diffusion plate SS according to FIG. 10, it differs from the embodiment according to FIG. 9 in that the front wide strip area SB1 of the carrier plate TP extends into an elongated central strip area covered with the prism plate PF on the light incidence side SB11 and two short edge strip areas SB12 and SB13 is divided. The short edge strip areas SB12 and SB13 are covered on the light incidence side with a lacquer layer or a plastic film, which have a light transmittance of 10 to 20%.

The lacquer layers or plastic films in the area of the narrow rear stripe area SB2 and in the area of the short edge stripe areas SB12 and SB13 must be designed so that they appear structureless in transmitted light, i.e. have a uniform "cloud-free" pigmentation. Furthermore, the light transmission must be aselective, i.e. the light from the fluorescent lamp arrangement must not have a color cast after it has passed through the lacquer layer or the plastic film. A varnish or a plastic film in white, gray or silver color is expediently considered.

In order to ensure that in the embodiment according to FIG. 10 no disturbing gap occurs in the transition area between the elongated central stripe area SB11 and the short edge stripe areas SB12 and SB13, it is expedient here to overlap the prismatic film PF with the lacquer layer or the plastic film cover from 5 mm.

It is for lighting workplaces where electrostatic sensitive devices are used It is useful to provide acrylic glass or polycarbonate with a conductive coating as the carrier plate TP of the diffusing screen SS. Such material is commercially available, for example, under the name "ESLON DC-PLATE".

In this case, the carrier plate TP of the diffusing screen must then be treated with a conductive “final coating liquid” on the edge and, moreover, a ground contact must be attached to the carrier plate by means of a conductive adhesive.

In a preferred embodiment of the workplace lamp for a workplace according to FIG. 1, the following dimensions result:
α = 10 °
β = 8 °
γ> 30 °
δ = 20 °
a = 12 mm
d = 26 mm
b = 42 mm
c = 12.5 mm
e = 38 mm
f = 35 mm
g = 240 mm
Prism grid film: "3M Scotch Optical Lighting Film (grid dimensions corresponding to FIG. 6).

Claims (17)

1. Workplace luminaire of small mounting height, which is fastened with its rear at a prescribed height above a work table and has a flat, box-shaped housing trough which extends in the longitudinal direction of the work table and in which there are arranged a fluorescent lamp arrangement, extending over the length of the housing trough, and light-guiding and electrical components, and whose light exit opening, which is directed towards the work table, is covered by a diffusing screen, characterized in that

   - seen in the direction towards the rear of the work table (AT), the fluorescent lamp arrangement (LL) is arranged in the rear region of the housing trough (G) and in front thereof a plane main reflector (R1), which extends over the entire length and in width up to the front side wall (G2) of the housing trough, is arranged inclined to the diffusing screen (SS) at an angle α, within the limits 10° ≦ α ≦ 20°, opening rearwards, whose rear edge (R11), which extends parallel to the fluorescent lamp arrangement, is situated above and in front of the fluorescent lamp arrangement (LL) at a horizontal distance (b) which is chosen such that the preponderant proportion of the light (LI) emitted by the fluorescent lamp arrangement is deflected at the main reflector against the diffusing screen (SS) at an angle γ > 30° relative to the vertical, and

   - directly in front of and below the fluorescent lamp arrangement an auxiliary reflector (R2), likewise extending over the length of the housing trough, is provided in the direction of the direction of inclination of the main reflector, but at a smaller setting angle β within the limits 5° ≦ β ≦ 15°, the width (c + e) of which auxiliary reflector is greater, when projected onto the horizontal, than the distance (b) of the main reflector from the fluorescent lamp arrangement.
2. Workplace luminaire according to Claim 1, characterized in that

   - at its end facing the fluorescent lamp arrangement (LL) the auxiliary reflector (R2) changes into an angled foot (R22) which extends in the space below the fluorescent lamp arrangement (LL) and whose width (c) determines the degree of screening of the light (LI) irradiated directly downwards onto the diffusing screen (SS).
3. Workplace luminaire according to Claim 1 or 2, characterized in that

   - over the extent of the housing trough (G) the diffusing screen (SS) is subdivided into a front, wide strip area (SB1) and a rear, narrow strip area (SB2),

   - at least the wide strip area (SB1) is configured as a prismatic plate having mutually parallel prisms in a fine structure on the light incidence side, specifically having prisms extending perpendicular to the longitudinal extent of the work table (AT), and

   - the width (f) of the narrow strip area (SB2) is chosen to be so large that the transition between the two strip areas (SB1/SB2) is screened from the auxiliary reflector (R2) or its angled foot (R22) with respect to the light directly incident on the diffusing screen (SS).
4. Workplace luminaire according to one of the preceding claims, characterized in that

   - with the inclusion of the auxiliary reflector (R2) the main reflector (R1) is bounded on both sides at a right angle thereto by triangular or trapezoidal, inherently plane end reflectors (R3).
5. Workplace luminaire according to one of the preceding claims, characterized in that

   - the length of the housing trough (G), the length of the linear fluorescent lamp arrangement (LL) and the length (lt) of the work table (AT) are adapted to one another.
6. Workplace luminaire according to one of the preceding claims, characterized in that

   - the prisms of the diffusing screen (SS), which is configured as a prismatic plate, are constructed as a 45° prismatic raster (P).
7. Workplace luminaire according to one of the preceding claims, characterized in that

   - the 45° prismatic raster (P) of the diffusing screen (SS), which is configured as a prismatic plate, has a raster width (RB) of 0.35 mm and a raster depth (RT) of 0.17 mm.
8. Workplace luminaire according to one of the preceding claims, characterized in that

   - the main reflector (R1) and the two end reflectors (R3) are configured from anodized aluminium sheet having satin-frosted reflecting surfaces, and the auxiliary reflector (R2) is configured from anodized aluminium sheet having a high-gloss reflecting surface.
9. Workplace luminaire according to one of the preceding claims, characterized in that

   - the width (e), projected onto the horizontal, of the auxiliary reflector (R2) is chosen to be so large that given a normal eye position (AP) the fluorescent lamp arrangement (LL) cannot be seen in the direction of view towards the rear of the work table (AT).
10. Workplace luminaire according to one of the preceding claims, characterized in that

    - the diffusing screen (SS) is fastened in a lightproof fashion to the edges of the housing trough (G).
11. Workplace luminaire according to one of the preceding claims, characterized in that

    - the diffusing screen (SS), which is configured as a prismatic plate, comprises a backing plate (TP) made from clear glass or a clear art glass, for example plexiglass, which backing plate is provided on the side of light incidence with a clear prismatic film (PF) having the fine prismatic structure.
12. Workplace luminaire according to one of the preceding claims, characterized in that

    - the rear, narrow strip area (SB2) of the diffusing screen (SS) is likewise configured with mutually parallel prisms in a fine structure on the side of light incidence, and in that

    - in this case the prisms extend over the extent of the work table (AT) in its width (bt) at an angle δ within the limits 20° ≦ δ ≦ 40° and in a mirror-image fashion relative to one another with respect to a centre line (M) of the narrow strip area (SB2), which is subdivided once more in the centre of its length.
13. Workplace luminaire according to one Claims 1 to 11, characterized in that

    - on the side of light incidence the rear, narrow strip area (SB2) of the backing plate (TP) of the diffusing screen (SS) is provided with a lacquer coating or covering of plastic film having an optical transmittance of 5 to 10 %.
14. Workplace luminaire according to one of the preceding claims, characterized in that

    - over its extent the wide, front strip area (SB1) of the backing plate (TP) of the diffusing screen (SS) is subdivided into an elongated centre strip area (SB11), configured with prisms, and two short edge strip areas (SB12, SB13) free from prisms,

    - on the side of light incidence these edge strip areas (SB12, SB13) are provided with a lacquer coating or covering of plastic film having an optical transmittance of 10 to 20 %, and in that

    - the width of the edge strip areas (SB12, SB13) is approximately the width of the narrow, rear strip area (SB2).
15. Workplace luminaire according to one of the preceding claims, characterized in that

    - the backing plate (TP) of the diffusing screen (SS) is provided on its side of light incidence, including the covering of film or lacquer coating supporting it, with a covering (TAP) in the form of a clear glass plate or clear art glass plate, for example plexiglass.
16. Workplace luminaire according to Claim 15, characterized in that

    - the clear prismatic film (PF) which has the fine prismatic structure, is clamped as far as possible without adhesive between the backing plate (TP) and the covering (TAP), and for this purpose the backing plate (TP) and the covering (TAP) are bonded to one another on the edge side in such a way that the interspace between the two plates is simultaneously sealed with respect to the outside.
17. Workplace luminaire according to one of the preceding claims, characterized in that

    - the backing plate (TP) of the diffusing screen (SS) is provided with a conductive coating which is connected to frame potential in an effectively conducting fashion.

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