WO1997045674A1

WO1997045674A1 - High aspect ratio light source controller

Info

Publication number: WO1997045674A1
Application number: PCT/US1997/008276
Authority: WO
Inventors: Timothy Fohl
Original assignee: Timothy Fohl
Priority date: 1996-05-30
Filing date: 1997-05-15
Publication date: 1997-12-04

Abstract

A high aspect ratio light source controller including an array of angle transformers (10a, 10b) each including: an input end (12a) proximate the light source (14), an axial collimator (18a) having an interior surface which collimates light directed therein, and a light guide section (16a) for directing light from the input end (12a) to the axial collimator (18a); the input ends of each angle transformer being aligned along the longitudinal axis of the light source (14); and adjacent axial collimators (18b) displaced with respect to each other along an axis transverse to the longitudinal axis of the light source (14) for collimating light from the source substantially along its longitudinal axis.

Description

HIGH ASPECT RATIO LIGHT SOURCE CONTROLLER

FIELD OF INVENTION This invention relates to a high aspect ratio light source controller which controls light in all directions from a light source such as a tubular fluorescent lamp without inherent losses.

BACKGROUND OF INVENTION

It is often desirable to control light from light sources by directing the light into a limited range of angles. Such controllers allow more light to be deposited on the area or areas to be illuminated and prevent light from reaching areas where it is not needed or wanted. In an office environment, such light control devices reduce the power required to provide the necessary level of illumination resulting in lower power usage in the lamps and attendant cooling systems. Such controllers also reduce glare which can interfere with work tasks particularly in rooms where videos display terminals (VDT) are used.

Certain types of light sources, called low aspect ratio light sources, are relatively easy to control. Light fixtures for these light sources can be easily fitted with effective light control optics such as reflectors and lenses. Typical low aspect ratio sources are incandescent lamps (e.g., a 100 watt household light bulb) and high intensity (HID) arc lamps.

Other commonly used light sources, however, called high aspect ratio sources, have very different dimensions in different directions. Typical high aspect ratio sources include fluorescent lamps whose tubes are often forty times longer than their diameters. Such lamps present difficult problems for light control because of their shape. It is not very difficult to control light in the direction perpendicular to the longitudinal axis of the lamp, but conventional optical systems would be unacceptably large to control light efficiently in the direction parallel to a longitudinal axis of the lamp.

Most fluorescent lamp fixtures do not control light beyond a minimal amount and are therefore not very energy efficient. In some situations where glare is a problem, fluorescent fixtures may be provided with reflectors which focus the light into a limited range of angles perpendicular to the tube axis. In the direction parallel to the longitudinal axis of the fluorescent lamp, the light may be controlled through the use of baffles which absorb the unwanted light or by reflectors which inherently reject a certain fraction of the light. Thus, the optical gain is limited to that obtained by focusing in the direction perpendicular to the longitudinal axis of the lamp only. Once such controller which uses reflectors is called the "P 4 Parabolume" available from Columbia Lighting of Spokane, Washington.

SUMMARY OF INVENTION

It is therefore an object of this invention to provide a high aspect ratio light source controller.

It is a further object of this invention to provide such a high aspect ratio light source controller which controls light in all directions without inherent losses.

It is a further object of this invention to provide such a high aspect ratio light source controller which reduces the angular spread of light from a typical fluorescent lamp in the axial direction by as much as a factor of two or three.

It is a further object of this invention to provide such a high aspect ratio light source controller which can direct as much as two or three times as much light onto a work surface without increasing the number of light sources.

It is a further object of this invention to provide such a high aspect ratio light source controller which reduces glare.

It is a further object of this invention to provide such a high aspect ratio light source controller which reduces the number of light sources needed to properly illuminate a given area thereby decreasing the energy usage.

This invention results from the realization that a significant energy and cost savings can be accomplished in the use of high aspect ratio light sources such as fluorescent lamps by using different geometry angle transformers disposed along the length of the lamp in such a way that the output ends of the transformer are displaced along an axis transverse to the longitudinal axis of the lamp so that the input ends of each transformer can then be disposed closely adjacent to each other along the longitudinal axis of the lamp to capture, redirect and even collimate substantially all of the light from the lamp.

This invention features a high aspect ratio light source controller. There is an array of angle transformers each including: an input end proximate the light source, an axial collimator having an interior surface which collimates light directed therein, and a light guide section for directing light from the input end to the axial collimator. The input ends of each angle transformer are aligned along the longitudinal axis of the light source and adjacent axial collimators are displaced with respect to each other along an axis transverse to the longitudinal axis of the light source for collimating light from the source substantially along its longitudinal axis.

The light source may be a tubular lamp such as a fluorescent lamp. The input end of each transformer is preferably curved to match the curvature of the tubular lamp. Each transformer preferably extends in a direction transverse to the longitudinal axis of the light source.

There may be two transformer arrays, a first array disposed on one side of the light source and a second array disposed on the opposite side of the light source, each array including rows of axial collimators extending in the direction of the longitudinal axis of the light source and columns of axial collimators extending in a direction transverse to the longitudinal axis of the light source. Such a controller preferably includes reflective elements extending outwards from the light source in the direction of the columns of axial collimators and longitudinally along the light source in the direction of the rows of axial collimators.

In a preferred embodiment, the transformers are solid and formed of an acrylic material. This invention also features a tubular lamp light controller comprising: a plurality of transformers each including an input end proximate the light source, an axial collimator having an interior surface which collimates light directed therein, and a light guide section for directing light from the input end to the axial collimator. A first array of the transformers is disposed with the input ends of each transformer of the first array extending along the longitudinal axis of the tubular lamp on one side thereof and a second array of the transformers are disposed with the input ends of each transformer of the second array extending along the longitudinal axis of the tubular lamp on the opposite side thereof. Such a controller further includes two opposing pairs of reflective elements extending along the longitudinal axis of a tubular lamp, each pair disposed for directing light to the opposing arrays of transformers.

This invention also features a tubular lamp light controller comprising: reflective means for directing light from the tubular lamp substantially in a first direction transverse to the longitudinal axis of a tubular lamp; and a plurality of transformers each including: an input end proximate the tubular lamp, an axial collimator having an interior surface which collimates light directed therein, and a light guide section for directing light from the input end to the axial collimator. The input ends of each transformer are disposed along the longitudinal axis of the tubular lamp to receive light from the reflective means; and the axial collimators of each transformer are disposed for directing light substantially in a direction transverse to the first direction. The transformers form an array of axial collimators wherein adjacent axial collimators are disposed adjacent to each other. In a preferred embodiment, there are two arrays of axial collimators on opposite sides of the tubular lamp.

DISCLOSURE OF PREFERRED EMBODIMENT

Fig. 1 is a schematic view of three angle transformers used in the high aspect ratio light source controller of this invention;

Fig. 2 is a schematic view of six such angle transformers uniquely configured such that the input ends of each angle transformer are placed next to each other along the length of the lamp according to this invention;

Fig. 3 is a top schematic view of opposing arrays of angle transformers in another embodiment of the high aspect ratio light source controller of this invention;

Fig. 4 is a bottom view of the angle transformers shown in Fig. 3;

Fig. 5 is a top schematic view of another embodiment of the angle transformers of this invention;

Fig. 6 is a conceptualized view showing a portion of two opposing arrays of angle transformers in one embodiment of the high aspect ratio light source controller of this invention; Figs. 7 and 8 are conceptualized views of still another embodiment of one portion of the high aspect ratio light source controller of this invention;

Fig. 9 is a conceptualized view of the complete high aspect ratio light source controller device of this invention; and

Fig. 10 is a schematic view showing the improvement in the angular spread of light in the axial direction of a fluorescent lamp due to the use of the high aspect ratio light source controller device shown in Fig. 9.

Angle transformer 10a, Fig. 1, of this invention includes input end 12a placed proximate light source 14 (e.g. a fluorescent lamp). Light guide section 16a directs light from input end 12a to axial collimator 18a which has an interior surface that collimates all light directed therein as shown by vectors 22 and 24. The purpose of transformer 10a, Fig. 1, is to capture undirected light from lamp 14 at input end 12a and direct the undirected light in the direction as shown by vectors 22 and 24.

Angle transformer 10a is made of a solid piece of clear acrylic (e.g. lucite) approximately 1.5 inches thick, 4 inches long, 4 inches wide at output portion 26, and 2 inches wide at light guide section 16. As shown in Fig. 1, however, the input ends 12a and 12b of two such angle transformers 10a, and 10b, cannot be placed next to each other because of the geometry of the adjacent axial collimators 18a and 18b. This results in a loss in region 30 between the two transformers 10a and 10b.

In this invention, however, adjacent angle transformers 10c and lOd, Fig. 2, have axial collimators 18c and 18d which are displaced with respect to each other along axis 32 orthogonal to the longitudinal axis 34 of lamp 14 by virtue of angled light guides 16c and 16d. In this way, the input ends 12c and 12d of adjacent transformers 10c and lOd are in close proximity to each other and aligned along the longitudinal axis 34 of lamp 14 thus eliminating any area of non-directed light such as area 30, Fig. 1. An array of such transformers lOc-lOh, Fig. 2, is thus formed to redirect light from one side of lamp 14.

In another embodiment, the light guide sections 16i, 16j, Fig. 3, are angled with respect to axis 32 orthogonal to the longitudinal axis 34 of the lamp as shown forming four rows of axial collimators. As seen from the rear and bottom, Fig. 4, the input ends 12i and 12j of adjacent angle transformers abut each other in the direction of the longitudinal axis of the lamp so that no losses occur. As shown in Fig. 5, each row of each array may include a plurality of axial collimators. Thus, as shown in Fig. 6, there are two arrays 40 and 42 of angle transformers on opposite sides of lamp 14. Each array includes N (e.g. N=4) rows 46 of axial collimators by orienting adjacent axial collimators lOj and 10k next to each other in the direction transverse to the direction of longitudinal axis 34. The 5th, 9th, and 13th (axN+ 1 to N-l) axial collimators begin a new row. As can be seen in Fig. 6, virtually the entire surface area of lamp 14 can be covered by the input ends of the transformers aligned along longitudinal axis 34 of lamp 14.

In the embodiment shown in Fig. 6, four rows of axial collimators result in a X4 reduction in the angular spread of light from fluorescent lamp 14 (e.g. 180° to 45°). Three rows result in a reduction of X3 (e.g. 60°) and two rows result in a reduction of X2 (e.g. 90°). In order to cover the entire surface of fluorescent lamp 14, the dimension of input end 12i, Fig. 4, of each angle transformer in the direction of die longitudinal axis of the lamp is 1/N times the dimension of axial collimator 18i portion in the same direction and there are N rows of angle transformers. Conversely, if there are N rows of angle transformers, the dimension of the axial collimator portion of each angle transformer in the direction of the longitudinal axis of the lamp is N times the dimension of the input end of each angle transformer in the same direction. This results in an array of angle transformers whose input ends abut each other in the direction of the longitudinal axis of the lamp and whose axial collimator portions abut each other in the same direction.

In another embodiment, opposing reflective elements 50 and 52, Figs. 7 and 8 are placed around lamp 14 as shown and the input ends (e.g. 12n and 12m) of adjacent transformers lOn and 10m extend between the inside walls of each reflective element. In this embodiment, adjacent axial collimators lOp and lOq are placed adjacent to each other in the direction of axis 32. Every other axial collimator lOp and lOr are placed adjacent to each other in the direction of axis 34. Reflective elements 52 and 50 direct light from source 14 in a direction 32 transverse to the longitudinal axis 34 of source 14 and each array of the axial collimators re-directs the light in direction 33 transverse to direction 32. By constructing the light guide section to have different angles, other control aspect angles are possible. Such a device 60 is shown in Fig. 9 extending completely along the length of the lamp 14. As shown schematically in Fig. 10, device 60 thus provides light control in all directions without inherent losses. If the angular spread in the axial direction is reduced by a factor of 2 representing a 45° beam cut off as shown at 70 and 72, approximately twice as much light is directed to work surface 76 using one fluorescent lamp. If the angular spread is reduced by a factor of 3 representing a 30° beam cut off as shown at 78 and 80, approximately 3 times as much light as available at the work surface 76 through the use of device 60, Fig. 9 and 10.

Thus, device 60 allows the use of half the number of fluorescent bulbs in the case of a 45° beam cut off and 1/3 third the number of fluorescent bulbs in the case of a 30° beam cut off. The result is a substantial energy savings and a significant decrease in glare, a desirable feature for VDT rooms. Controller device 60, Fig. 10 controls light in all directions without inherent losses, reduces the angular spread of a typical fluorescent lamp in the axial direction by as much as a factor of two or three, and directs as much as two or three times as much light onto a work surface without increasing the number of light sources. The result is a significant energy savings.

Device 60, Figs. 8 and 9 can be used in conjunction with any type of high aspect ratio light source including neon lights, fluorescent lamps, apertured lamps, other curved or straight tubular lamps, diode laser arrays, and even some types of long thin filament lamps. Although each angle transformer discussed above is formed from a single piece of acrylic such as lucite, other angle transformers may be used including hollow chambers with reflective interior surfaces and other optical systems which accomplish the same result such as fiber optic systems. The axial collimator described above includes any optical device which redirects high angle light rays to the direction of the axis of the plane of symmetry of the axial collimator. Small angle light rays are unaffected. True collimation may not be possible in all embodiments and the phrase "axial collimator" is to be interpreted in the broadest sense.

Although specific features of the invention are shown in some drawings and not others, this is for convenience only as some feature may be combined with any or all of the other features in accordance with the invention. Other embodiments will occur to those skilled in the art and are within the following claims:

Claims

1. A high aspect ratio light source controller comprising: an array of angle transformers each including: an input end proximate the light source, an axial collimator having an interior surface which collimates light directed therein, and a light guide section for directing light from the input end to the axial collimator; said input ends of each angle transformer being aligned along the longitudinal axis of the light source; said axial collimators oriented to direct light in a direction transverse to the longitudinal axis of the light source.

2. The controller of claim 1 in which the light source is a tubular lamp.

3. The controller of claim 2 in which the tubular lamp is a fluorescent lamp.

4. The controller of claim 2 in which the input end of each transformer is curved to match the curvature of the tubular lamp.

5. The controller of claim 1 in which each transformer extends in a direction transverse to the longitudinal axis of the light source.

6. The controller of claim 5 including two transformer arrays, the first array disposed on one side of the light source, the second array disposed on the opposite side of the light source, each array including rows of axial collimators.

7. The controller of claim 6 further including reflective elements extending outwards from the light source in the direction of the columns of axial collimators and longitudinally along the light source in the direction of the rows of axial collimators.

8. The controller of claim 1 in which the transformers are solid and formed of an acrylic material.

9. The controller of claim 1 in which there are N rows of angle transformers.

10. The controller of claim 9 in which the dimension of the axial collimator of each angle transformer in the direction of the longitudinal axis is N times the dimension of the input end of each angle transformer in the same direction.

11. A tubular lamp light controller comprising: a plurality of transformers each including; an input end proximate the light source, an axial collimator having an interior surface which collimates light directed therein, and a light guide section for directing light from the input end to the axial collimator; a first array of said transformers disposed with the input ends of each transformer of the first array extending along the longitudinal axis of the tubular lamp on one side thereof; and a second array of said transformers disposed with the input ends of each transformer of the second array extending along the longitudinal axis of the tubular lamp on the opposite side thereof.

12. The controller of claim 11 further including two opposing pairs of reflective elements extending along the longitudinal axis of a tubular lamp, each pair disposed for directing light to the opposing arrays of transformers.

13. A tubular lamp light controller comprising: reflective means for directing light from the tubular lamp substantially in a first direction transverse to the longitudinal axis of a tubular lamp; a plurality of transformers each including: an input end proximate the tubular lamp, an axial collimator having an interior surface which collimates light directed therein, and a light guide section for directing light from the input end to the axial collimator; the input ends of each transformer being disposed along the longitudinal axis of the tubular lamp to receive light from said reflective means; and the axial collimators of each transformer disposed for directing light in a direction substantially transverse to the first direction.

14. The controller of claim 13 in which the transformers form an array of axial collimators wherein adjacent axial collimators are disposed adjacent to each other.

15. The controller of claim 14 in which there are two arrays of axial collimators on opposite sides of the tubular lamp.