Lamp distribution modifier and luminaire having the same

A luminaire for mounting on a vertical surface is provided, the luminaire including a housing having an aperture, a lamp disposed within the aperture and configured to emit light through the aperture to the vertical surface and to an associated worksurface, and a lamp distribution modifier disposed within the aperture proximate to the lamp, where the lamp distribution modifier is configured to intercept light rays emitted by the lamp in a direction toward an upper portion of the vertical surface.

BACKGROUND OF INVENTION

(a) Field of Invention

The present invention relates generally to luminaires which are mountable on vertical surfaces. More specifically the invention relates to a panel-mounted luminaire, such as those used with partition panels in modular office furniture systems, where the luminaire is configured to reduce excessive luminance on the vertical surface while still providing sufficient luminance to said vertical surface and/or an associated worksurface.

(b) Description of Related Art

Luminaires are often used in conjunction with conventional modular office furniture systems. Such luminaires may be task lights that direct their output in a downward direction only to illuminate worksurfaces located below the luminaires, ambient lights that direct their output in an upward direction only to illuminate ceilings and give general lighting to the space, or task/ambient luminaires that provide both downward and upward directed light. These luminaires are often fashioned as elongated units suitable for use with linear type fluorescent lamps and are capable of providing broad areas of lighting for horizontal worksurfaces and associated partition panels.

Workstation integrated task and task-ambient luminaires are well known in the industry and are especially effective at achieving quality task illumination in open office environments. Generally, such luminaires are configured to mount on open office workstation partitions, walls, or, as may be the case with those that provide only downward task lighting, to an underside of workstation shelves or elevated storage cabinets (also known as “binder bins”).

Linear type fluorescent lamps of nominal 1″ diameter (T8) or ⅝″ diameter (T5) are the most popular lamps for applications involving these task and task-ambient luminaires. Consequently, installations typically consist of luminaires ranging from 2 feet in length to as much as 8 feet in length, each incorporating 2′, 3′, 4′, or 5′ long fluorescent lamps singly or in tandem as dictated by the length of the unit. Common desirable mounting practices typically position the luminaires slightly above seated eye height and coincident to a primary task area of a worksurface generally disposed horizontally some distance beneath the mounted task luminaire. Worksurfaces that are 24 to 30 inches deep (front to back) and 6 to 8 feet long are common and are desirably served by task lighting that extends nearly or completely over an entire length of the worksurface, thus providing broad and relatively uniform areas of task lighting within the workstation.

In addition to lighting the requisite horizontal worksurface, much effort is often taken in the design of such luminaires to similarly illuminate the vertical surface that typically extends upwardly from the edge of the worksurface opposite from the viewer. This vertical surface may be a wall, a privacy partition panel, etc. These efforts are generally directed at alleviating shadowing of overhead ambient lighting by said luminaire, shelf and/or binder bin in an attempt to create a balanced luminous surround for vertically oriented visual tasks (such as VDT viewing) in addition to traditional paper tasks.

Specifically, a desirable visual balance may be achieved when the luminance ratio between a task and the immediately adjacent surroundings (workstation surfaces) does not exceed 3:1 or 1:3. (ref: ANSI/IESNA RP-1-04 American National Standard for Office Lighting). Thus, for the typical VDT screen with an average luminance of 90 candelas per square meter (cd/m2), the vertical workstation panel(s) adjacent to said VDT should have a luminance in the range of 30 to 270 cd/m2. The industry Standards further recommend that such panels have a reflectance of 40% to 70% and be non-specular (i.e. diffuse). Therefore, such luminances are typically realized when such workstation panels are illuminated to 22 to 114 footcandles. However, current task-oriented workstation luminaires often do not provide this luminance balance, thus resulting in visual fatigue and discomfort to the viewer as the worker's eye repeatedly adjusts to disparate luminances in the field of view. Such visual fatigue and discomfort is known to diminish the productivity of the affected worker in performing workstation tasks.

Furthermore, in using such task oriented workstation luminaires, it is often desirable to achieve a narrow profile, i.e., a narrow outward extension from the vertical surface, in order to: (1) achieve a spacious and open feeling workstation; (2) minimize any shadow the luminaire might cast on workstation surfaces due to overhead ambient lighting; (3) minimize any asymmetric weight load/moment on the supporting panel and/or brackets; and (4) minimize fabrication costs associated with larger luminaire units. However, a task luminaire having a smaller cross-section and a corresponding reduced extension from the vertical surface generally places the lamp closer to the vertical surface thus causing luminance of the vertical surface proximate to the aperture to exceed the recommended limits.

Therefore, a luminaire is desired that overcomes these disadvantages and offers improved luminance distribution across a vertical mounting surface and an associated worksurface. Specifically, a luminaire is desired having a lamp distribution modifying feature which reduces luminance on the vertical mounting surface proximate to the luminaire while maintaining sufficient luminance on areas of the mounting surface disposed distally relative to the luminaire and across the associated worksurface, where such feature is discrete so as not to detract from the aesthetics of the luminaire, and where such feature is cost-effectiveness, easy to install, and capable of retrofit and reposition.

SUMMARY OF INVENTION

A luminaire for mounting on a vertical surface is provided, the luminaire including a housing having an aperture, a lamp disposed within the aperture and configured to emit light through the aperture to the vertical surface and to an associated worksurface, and a lamp distribution modifier disposed within the aperture proximate to the lamp, where the lamp distribution modifier is configured to intercept light rays emitted by the lamp in a direction toward an upper portion of the vertical surface.

A lamp distribution modifier is further provided where the modifier is disposed proximate to a lamp within an interior of a downlight luminaire. The modifier generally includes an elongated body configured to extend along at least a part of a length of the lamp, a light passage feature disposed on the body configured to allow first light rays incident on a vertical surface to pass through the lamp distribution modifier, and a light intercepting feature disposed on the body and configured to intercept second light rays incident on the vertical surface. The body is disposed so as not to be directly visible to a viewer of the luminaire.

The invention also provides a method of modifying light incident on a vertical surface emitted by a lamp of a luminaire mounted proximate to the vertical surface. The method includes disposing a lamp distribution modifier at an interior of the luminaire proximate to the lamp so as not to be directly viewable by a viewer of the luminaire, intercepting first light rays at the lamp distribution modifier incident on an upper portion of the vertical surface proximate to the luminaire, and allowing passage of second light rays through the lamp distribution modifier incident on the upper portion of the vertical surface and incident on a lower portion of the vertical surface disposed distal from the luminaire.

The above discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a side view of a workstation10comprised of a vertical surface12and a worksurface14. The vertical surface may be a wall or a privacy partition common to modular furniture arrangements or any vertical surface sufficient for use in the workstation10. For simplicity purposes, the vertical surface12is herein described as generally being oriented vertically. It shall be understood that this surface12may be angled relative to vertical, as desired. The worksurface14is shown as a horizontal surface extending generally perpendicularly from the vertical surface12in a direction toward a viewer16who is disposed in a seated or standing position at the workstation10. The worksurface14may be formed integrally with the vertical surface, attached fixedly thereto, or may be separate therefrom and maybe horizontal, inclined, and/or declined, as desired. An exemplary monitor18is positioned on the worksurface14.

The workstation10further includes a luminaire20in an exemplary embodiment of the invention. The luminaire20is mounted to the vertical surface12at a height slightly above the eyes of the viewer16and is configured to illuminate the vertical surface12and the worksurface14. The luminaire20may be fixed to the vertical surface12by any sufficient means including bolts, fasteners, etc. Alternatively, the luminaire20may be removably attached to the vertical surface12by being hung upon brackets (not shown) which extend from the vertical surface12and which are received in a slot or groove formed in a rear section of the luminaire20. Particularly, the luminaire20is mountable on the vertical surface12using the bracket configuration disposed in U.S. patent application Ser. No. 11/402,358, entitled, “LUMINAIRE WITH MULTI-PURPOSE MOUNTING FEATURE”, filed by David Pfund et al. on Apr. 11, 2006, the entire contents of which are herein incorporated by reference in their entirety. The luminaire20extends along the vertical surface12in a direction generally parallel to a line formed by the intersection of the vertical surface12and the worksurface14. The luminaire20may be of any desired length and is preferably from two feet to eight feet long. The workstation10may include a single luminaire20or multiple luminaires20mounted on the vertical surface adjacent to one another.

FIG. 2illustrates a cross-section of the luminaire20and a portion of the vertical surface12. As shown, the luminaire20includes a housing22which delimits an upper aperture24and a lower aperture26. A lamp28is disposed within the housing generally between the upper and lower apertures24and26, respectively. The lamp28is generally a fluorescent tube lamp and, for example, may be a T8 lamp (one inch diameter) or a T5 lamp (⅝ inch diameter), or any other desired tube lamp fluorescent or otherwise. The lamp28is removably disposed within the housing22by conventional means comprising one or more lampholder, a ballast, etc. such that the lamp28extends along at least a part of the length of luminaire20. The upper aperture24is positioned to allow light emitted from the lamp28to emanate upward relative to the luminaire20. The lower aperture26is positioned to allow light emitted from the lamp28to emanate downward relative to the luminaire20.

The luminaire20further includes a first reflector30and a second reflector32disposed within the housing22at the aperture26on opposite sides of the lamp28. The first reflector30is disposed toward a front of the housing22. The second reflector is disposed toward a rear of the housing22proximate to the vertical surface12. The first and second reflectors30and32generally comprise specular members which extend partly or entirely along the length of the lamp28and which are configured to receive light emitted from the lamp28and to redirect said light toward the vertical surface12and/or toward the worksurface14. The first and second reflectors30and32, in an exemplary embodiment, are those disclosed in U.S. patent application Ser. No. 11/404,356, entitled, “LUMINAIRES HAVING A CONTOURED SURFACE THAT REDIRECTS LIGHT”, filed by David Pfund et al. on Apr. 12, 2006, the entire contents of which are herein incorporated by reference in their entirety. The first and second reflectors30and32are rigidly fixed with in the housing22by conventional means such as screws, bolts, etc., or, alternatively may be formed integrally with the housing22.

The luminaire20further optionally includes a lens34disposed beneath the lamp28within the aperture26between the first and second reflectors30and32. The lens34partially or entirely surrounds the lamp28and includes one or more areas of opacity and/or translucency for regulating light emitted from the lamp28. The lens34may be slidably movable along the length of the lamp28or may extend the entire lamp length.

The luminaire20additionally includes a lamp distribution modifier36disposed within the aperture26proximate to the lamp28and inside of the lens34(if present in the luminaire20). As will be discussed herein in detail, the lamp distribution modifier36is generally disposed and configured to allow certain light rays from the lamp28to pass freely therethrough while intercepting other light rays in order to provide the vertical surface12and the worksurface14with a substantially even light distribution, while at the same time being disposed proximate to the lamp28within the housing22out of the view of the viewer16. That is, the lamp distribution modifier36allows certain emitted light rays to pass freely therethrough to the first reflector30, to the second reflector32, to the vertical surface12, and/or to the worksurface14. The lamp distribution modifier36further intercepts other light rays directed toward an upper portion (discussed herein below) of the vertical surface12in order to prevent overexposure of this portion of the surface12. The modifier36provides these advantages while being disposed within the lower aperture26so as not to intercept light rays exiting the luminaire after being advantageously redirected by reflectors30and32and so as not to be readily visible by the viewer16thus not depreciating the aesthetics of the luminaire20.

The lamp distribution modifier36comprises an elongated member which extends partly or entirely along the length of the lamp28. The lamp distribution modifier36may be rigidly fixed within the housing22or may be slidably moveable therein. The lamp distribution modifier36includes one or more light intercepting features38(see,FIGS. 6A,6B, etc.) which intercept certain light rays emitted from the lamp28. The lamp distribution modifier36further includes one or more light passage features40(see,FIGS. 6A,6B, etc.) which allow certain light rays emitted from the lamp28to pass freely from the lamp distribution modifier36. As alluded to above, the strategic disposition and configuration of the light intercepting and light passage features38and40result in an even distribution of light from the lamp28across the vertical surface12and across the worksurface14.

FIGS. 3 and 4show effects of the lamp distribution modifier36upon light rays emitted from the lamp28. For convenience purposes, not all light rays emitted from the lamp28are shown inFIGS. 3 and 4(e.g., light rays directed upward through upper aperture24are not shown) but it shall be understood that the lamp28emits light in all outward directions relative to the illustrated cross-section.

Referring toFIG. 3, light rays42are emitted from the lamp28in a direction toward the first reflector30which desirably redirects the light rays42toward a lower portion12A of the vertical surface12. Light rays44are emitted from the lamp28in a direction toward an upper portion12B of the vertical surface12. The lamp distribution modifier36is disposed between the lamp28and the upper vertical surface portion12B such that the intercepting features38intercept the light rays44and thus substantially prevent the light rays44from proceeding onward toward the upper portion12B. Light rays46are emitted from the lamp28in a direction toward the lamp distribution modifier36and are incident upon the light passage features40. Thus, the light rays46are permitted to substantially pass through the lamp distribution modifier36so as to illuminate the upper portion12B of the vertical surface. Notably, the lamp distribution modifier36is disposed within the lower aperture26closely proximate to the lamp28. In this manner, the viewer16does not have the occasion to readily view the modifier36, thus preserving the aesthetics of the luminaire20.

Referring now toFIG. 4, light rays48are emitted from the lamp28in a direction toward the worksurface14. As shown, the light rays48are not impeded by the first reflector30nor by the lamp distribution modifier36and thus are able to emanate directly to the worksurface14. Light rays50are emitted from the lamp28in a direction toward the second reflector32. As shown, the light rays50emanate adjacent to and unimpeded by the lamp distribution modifier36so as to contact the second reflector32which redirects the light rays50in a direction toward the work surface14. Light rays52represent another set of light rays emitted from lamp28in a direction toward the lamp distribution modifier36and are incident upon the light passage features40. Thus, the light rays52are permitted to substantially pass through the lamp distribution modifier36so as to contact reflector32which redirects the light rays52in a direction toward worksurface14. Similarly, light rays54are emitted from lamp28in a direction toward the lamp distribution modifier36. However, light rays54are incident upon the intercepting features of the lamp distribution modifier36and are thus prevented from contacting reflector32. It is therefore advantageous that the distribution modifier36be fashioned, as in the embodiments described below, to intercept light rays44(FIG. 3) to a much greater extent than it may intercept light rays54(FIG. 4).

It is widely known that luminance on a plane is depreciated by (a) the distance from the source and (b) the cosine of the angle of incidence of the light relative to the plane (measured from a line drawn normal to the surface). Thus, referring again toFIG. 3, in the arrangement of the workstation10it is important to provide reduced luminance to the upper portion12B of the vertical surface due to its proximity to the lamp28and due to the angle of light rays incident thereon. Correspondingly, it is also important to provide enhanced luminance to the lower vertical surface portion12A due to the increased distance of this portion relative to the lamp28and due to the increased angle of incident light. The interception of the light rays44by the lamp distribution modifier36, combined with the passage of light rays46through the modifier36, results in a reduced luminance at the upper vertical surface portion12B. The light rays42which bypass the modifier36and which are redirected toward the lower vertical surface portion12A by the first reflector30provide an increased luminance at this portion12A relative to the luminance at portion12B. Thus, the net effect of the luminaire20is a substantially even luminance distribution across the vertical surface12despite the proximity of the lamp28to the vertical surface12and particularly to the upper vertical surface portion12B, and despite the angle of light incident upon this upper portion12B.

This uniformity of luminance is provided to the vertical surface12with minimal interception of lamp emanations that directly illuminate the worksurface14or that can be desirably redirected by the first and or second reflectors30and32to indirectly illuminate the worksurface14. This is shown and described herein with respect toFIG. 4which illustrates light rays48emanating directly from the lamp28toward the worksurface14and light rays50and52being redirected by the second reflector32and thus sent indirectly to the worksurface14.

The lamp distribution modifier36may assume any number of a variety of configurations to provide these numerous advantages to the workstation10. Several representative configurations are now discussed. Notably all of the exemplary embodiments of the lamp distribution modifier36are disposed at an interior of the lower aperture26within the housing22so as not to intercept light rays exiting the luminaire after being advantageously redirected by reflectors30and32and so as to be kept out of sight from the viewer to thus preserve the aesthetic integrity of the luminaire20. Further notably, in many cases the modifier36may be retrofit into an existing workstation luminaire.

FIG. 5shows a simplified version of the luminaire20. Here it is shown that the lamp distribution modifier36includes a first edge A and an opposite edge B. The modifier36includes a varying degree of opacity between the edges A and B. Particularly, the least degree of opacity is found proximate to the edge A. The level of opacity provided by the modifier36gradually increases in a direction toward the edge B. Thus, the highest degree of opacity is found proximate to the edge B. That is, the direct lamp emanations intercepted by the lamp distribution modifier36is greatest toward the edge B.

The graduating degree of opacity of the lamp distribution modifier36may be accomplished by applying or infusing an opaque coating or material onto or into an otherwise clear material. For example, with reference toFIGS. 6A and 6B, the modifier36may comprise an elongate member having an arcuate cross-section where the member is formed of a generally transparent material, such as a plastic. This plastic material is then infused or masked with an opaque material or coating to result in the alternating light intercepting features38and light passage features. Here, when viewed in plan view as inFIG. 6A, the light intercepting and passage features38and40are substantially triangular in shape.

The lamp distribution modifier36may be disposed within the housing22by mounting brackets (not shown) or by fixation to ends of the housing22or by any either suitable fixation means. The modifier36is preferably disposed at an interior of the lower aperture26proximate and close to the lamp28so as to be kept out of view from the viewer16. This avoids aesthetic degradation of the luminaire, prevents the viewer from seeing any glare or reflection exhibited by the lamp distribution modifier36, etc. In the case where a lens34(FIG. 2) is present and is both proximate to the position of, and of a length corresponding to, a desirable lamp distribution modifier, it is herein also conceived that the requisite light intercepting and passage features38and40may be alternatively infused, masked or otherwise incorporated directly into or onto the lens34.

FIG. 7shows the luminaire20including a lamp distribution modifier56in another exemplary embodiment of the invention. Here, the modifier56is fashioned of an opaque material having opposite edges58and60and openings62delimited therebetween, as shown specifically inFIGS. 8A and 8B. An extension flange64extends along a length of the lamp distribution modifier56proximate to the edge58. The extension flange64allows the modifier56to be continuously or intermittently fixed into the luminaire20along a length thereof. The extension flange64is received and retained in the housing22just above the second reflector32. The flange64may be fixed in the housing22by way of a friction fit or by any other sufficient means such as screws, bolts, etc. The flange64includes mounting holes66to facilitate fixation of the flange64within the housing22of the luminaire20. The remainder of the modifier56extends downward relative to the flange64and curves to generally correspond with the circumference of the lamp28. In this way, the modifier56is resultantly disposed within the lower aperture26closely proximate to the lamp28so as not to intercept light rays exiting the aperture after being advantageously redirected by reflectors30and32and so as to be not readily viewable by the viewer16.

The openings62of the lamp distribution modifier56are shown as being substantially pentagonal in shape with their narrowest portion located proximate the edge60. Of course, the openings62may have any shape sufficient to allow light to pass through the modifier56as discussed in more detail below. In the embodiment ofFIGS. 7,8A, and8B, an upper line68comprises a line tangent to a side of the openings62proximate to the extension flange64. A lower line70represents a line tangent to a portion of the openings most proximate to the edge60. A mid-line72comprises a line extending generally between the upper and lower lines68and70. A point74lies on the upper line68while a point76lies on the mid-line72. Point74is coincident with a line78originating at an upper longitudinal edge80of the second reflector32and tangent to the lamp28. Point76is coincident with a line82originating at a lower longitudinal edge84of the second reflector32and tangent to the lamp28. As shown particularly inFIG. 8A, the points74and76define edges of the openings62.

A portion of the openings62disposed between the lines68and72is maximized to allow maximum direct lamp28emanations to pass through the lamp distribution modifier56and to enter onto the second reflector32. A portion of the openings62disposed between the lines70and72is tapered to allow a maximum of lamp28emanations to enter onto the second reflector while reducing the direct lamp28emanations incident on the vertical surface12of the workstation10.

The lamp distribution modifier56ofFIG. 7is similar to the modifier36discussed above in that the modifier56provides increasing opacity in a direction from the edge58toward the edge60. The opaque material forming the modifier56delimits the light intercepting features38proximate to the edge62and the light passage features40in the form of the openings62. The lamp distribution modifier56operates similarly to the modifier36discussed above. Particularly, the openings62permit light rays46(seeFIG. 3) to pass from the lamp28through the lamp distribution modifier56directly to the upper portion12B of the vertical surface12. Further, the light intercepting features38intercept light rays44thus preventing them from passing on to the upper vertical surface portion12B. The result is a reduction of light rays incident upon the upper vertical surface portion12B relative to the lower portion12A. The net effect is an even luminance distribution across the vertical surface12.

Of course the pentagonal shaped openings62, their regular spacing along the length of the lamp distribution modifier56and their identical size and shape (one to another) are only provided herein by way of example only. The openings62may possess any desirable shape and/or arrangement sufficient for providing the light distribution modification as intended by the broad scope of the invention. For example, the openings62may be triangular in shape, quadrilateral, curvilinear, etc. Likewise, openings of a multiplicity of shapes and/or sizes may be applied in a single embodiment of the invention.

FIG. 9shows the luminaire20including a lamp distribution modifier86in another exemplary embodiment of the invention. Here, the modifier86is fashioned of an opaque material having opposite edges88and90. The modifier86delimits the openings62as described above with reference toFIGS. 7,8A, and8B. (See,FIGS. 10A and 10B.) The modifier86also delimits second openings93disposed proximate to the edge90. The modifier86includes the extension flange64as addressed above which, here, extend along a length of the lamp distribution modifier86proximate to the edge88. A second extension flange95extends along the length of the modifier86proximate to the edge90. The extension flanges64and95allow the modifier86to be continuously or intermittently fixed into the luminaire20along a length thereof. The extension flange64, as discussed with reference to the modifier56, is received and retained in the housing22just above the second reflector32. The extension flange95is similarly received and retained above the first reflector30. The flanges64and95may be fixed in the housing22by way of a friction fit or by any other sufficient means such as screws, bolts, etc. The flanges64and95include mounting holes96to facilitate fixation of the flanges64and95within the housing22of the luminaire20.

In this embodiment, the dual flanges64and95provide a simple means of support and a more positive alignment of the lamp distribution modifier86within the housing22of the luminaire20while still allowing for the desired interception and passage of light rays emanating from the lamp28. The flanges64and95also result in a secure and close disposition of the modifier86relative to the lamp28. In this way, the modifier86does not intercept light rays exiting the aperture from reflectors30and32and is kept out of the view of the viewer16.

The lamp distribution modifier86ofFIGS. 9,10A, and10B includes the upper, lower, and mid-lines68,70, and72, respectively, described above with reference toFIGS. 7,8A, and8B. The modifier also includes the points74and76coincident with the lines78and82, respectively, as also described above. A point lies along a line100which traces an edge of the second openings93proximate to the edge90of the modifier86. This point98is coincident with a line102which originates at an upper longitudinal edge104of the first reflector30extends tangent to the lamp28.

The openings62of the lamp distribution modifier86are discussed in detail above with respect to the modifier56. Essentially, a portion of the openings62between the lines68and72is maximized to allow light emanating from the lamp28to pass directly through the modifier86to the second reflector32. Further, a portion of the openings62between the lines70and72is tapered to allow a maximum of lamp28emanations to enter onto the second reflector while reducing the direct lamp28emanations incident on the upper vertical surface portion12B of the workstation10.

The second openings93of the lamp distribution modifier86are generally rectangular in shape and are maximized to allow the maximum direct lamp28emanations to exit the lower aperture26of the luminaire20toward the worksurface14and to allow the maximum lamp28emanations to enter onto the first reflector30for redirection to the lower portion12A of the vertical surface12. (See,FIGS. 1-3.)

Here again, the lamp distribution modifier86operates similarly to the modifiers36and56discussed above. Particularly, the openings62permit light rays46(seeFIG. 3) to pass from the lamp28through the lamp distribution modifier86directly to the upper portion12B of the vertical surface12. Further, the light intercepting features38intercept light rays44thus preventing them from passing on to the upper vertical surface portion12B. Additionally, the openings93allow virtually unimpeded propagation of the light rays42and48to the first reflector30and to the worksurface14, respectively. The result is a reduction of light rays incident upon the upper vertical surface portion12B relative to the lower portion12A and uninhibited passage of light rays to the worksurface14. The net effect of the modifier86is an even luminance distribution across the vertical surface12and the worksurface14while the modifier86is maintained out of view from the viewer16so as to preserve the aesthetic quality of the luminaire20.

FIG. 10Cshows the lamp distribution modifier86in a different embodiment of the invention where the lower portion of the modifier86proximate to the line70is angular whereas this portion is more rounded in the embodiment ofFIG. 10B.

FIGS. 10D and 10Eshow a lamp distribution modifier116in another embodiment of the invention. Here, the openings62,93are reduced in number and/or size to effect a reduction of illuminance on the vertical surface12and/or on the worksurface14and/or to allow for use of a higher-output lamp28in the luminaire20to achieve greater uplight output through the upper aperture24without affecting the downlight output through the lower aperture26of the luminaire20. Of course the modifier86can take any shape or size to provide the desired lamp modification.

In accordance with another exemplary embodiment of the invention, at least a portion of a side of the lamp distribution modifier36,56,86,116facing the lamp28is provided with a reflective finish (not shown). That is, at least a portion of the side of the modifier36,56,86,116which faces the lamp28includes this reflective finish formed integrally on to the modifier36,56,86,116, coated thereon, etc. The reflective finish causes light that is intercepted by the modifier36,56,86,116to be redirected and distributed out through the upper aperture24in order to contribute to uplighting provided by the luminaire20.

FIG. 11shows the effect of the lamp distribution modifier36,56,86,116on the workstation10. Where illuminance generated by the luminaire20at points106,108,110, and112are measured perpendicular to the respective vertical surface12and worksurface14, both with and without the lamp distribution modifier36,56,86,116installed in the luminaire, it is found that the modifier36,56,86,116results in an illuminance reduction at point106of approximately 50and a corresponding illuminance reduction at point108of approximately 30%. This greatly improves luminance uniformity on the vertical surface and reduces the maximum illuminance to acceptable and desirable levels.

In one experiment, illuminance measurements taken perpendicularly at points106,108,110, and112were, respectively,195fc,55fc,110fcand90fc.Where the lamp distribution modifier of the invention was installed in the luminaire20, the illuminance measurements taken at points106,108,110, and112were, respectively,96fc,36fc,91fcand75fc.That is, the modifier resulted in an approximately 51% illuminance reduction at point106while only reducing illuminance approximately 35% at point108. Thus, the uniformity on the vertical surface12is improved from 3.5:1 to 2.7:1 and the maximum illuminance was reduced to an acceptable level (<114fc). At the same time, the illuminance at points110and112was reduced only 11% and 17% respectively.

Advantageously, the invention provides a luminaire that offers improved luminance distribution across a vertical mounting surface and an associated worksurface. Specifically, a luminaire is provided having a lamp distribution modifier which reduces luminance on the vertical mounting surface proximate to the luminaire while maintaining sufficient luminance on areas of the mounting surface disposed distally relative to the luminaire and across the associated worksurface, where such feature is discrete so as not to detract from the aesthetics of the luminaire, and where such feature is cost-effectiveness, easy to install, and capable of retrofit and reposition.