Abstract:
Task light units provide indirect lighting for task areas in front of computer monitors and other devices having display screens. Light is directed generally upwardly such that at least a portion of the light impinges upon a visor which is generally above the source of light. The visor reflects the light downwardly and generally forwardly toward a work or task area in order to indirectly illuminate that area. The task light components do not impart any direct light onto the display screen. Glare emanating from the task light is avoided, and eye strain is significantly reduced.

Description:
BACKGROUND OF THE INVENTION 
     This invention generally relates to a light for illuminating a task area, more particularly to a light which illuminates a task area by using indirect lighting which addresses eye strain concerns. The light is especially suitable to be mounted onto or positioned within the casing of a monitor of computer equipment with the objective of substantially reducing glare onto the display screen of the monitor, typically while providing beneficial indirect lighting for the task area being illuminated. 
     In the past, task lighting devices of various types have been provided or proposed for lighting task areas, while being directed toward reducing reflected glare. Some of them are intended to provide direct illumination of computer monitor display screens. For example, U.S. Pat. No. 5,722,754 attempts to ease eye strain by providing auxiliary lighting of a computer monitor display screen by illuminating it with simulated natural daylight from full spectrum bulbs. The display screen is intentionally and directly illuminated by the full spectrum illumination source. 
     Another type of task lighting is illustrated in U.S. Pat. No. 5,655,833, which provides a slidably mounted lighting fixture secured to the side panel of a computer monitor. This lighting fixture is designed to provide work surface illumination on a surface adjacent to a computer monitor and without unnecessarily increasing ambient room lighting. Another approach is proposed by U.S. Pat. No. 5,530,628, which shows a task light for use with office furniture systems having a backwall which is illuminated by the task light. 
     Task lighting fixtures of these general types light a task area or a monitor display. They do not concentrate upon lighting a task area which is in front of a display screen such as that of a computer monitor. None suggest the use of indirect lighting to achieve this type of task lighting. Relatively recent studies and observations have recognized a condition which has come to be known as Computer Vision Syndrome (or CVS), which is a repetitive stress injury, believed to be caused by the act of refocusing on a computer screen image again and again. Most users of computer monitors or other equipment incorporating self-illuminating display screens and the like are susceptible to suffering eyestrain. Symptoms of CVS include headaches, blurred vision and dry eyes. 
     CVS development typically is associated with decreasing of the blink reflex. Blinking can be reduced to an unnatural frequency when one stares into a computer monitor. An average person blinks twenty-two times per minute. During reading sharp black letters on white background, the rate decreases to twelve times per minute. At the computer, the blink reflex rate is reduced to only four times per minute. Such reduced blinking increases tear evaporation, resulting in a substantial increase in the exposure of the corneas. The result is dryer, more irritated eyes. 
     Unlike printed type which presents sharp edges in order to accurately interpret and maintain focus, users of display screens and computer monitors must focus and refocus involuntarily in an attempt to keep the images sharp. This is due in large part to the fact that display screens comprise pixels (minute subdivisions) which are very difficult for the human eye to keep in focus. Repetitive stress of the eye muscles results as the plane of focus drifts out to a resting point of accommodation. It is presently believed that this accommodation phenomenon is instrumental in the decreased blinking rate associated with computer use. 
     Glare from and at the workspace is a significant contributor to CVS. Ambient light which falls across a display screen has a lightening effect, decreasing contrast sharpness. Because of this uniform glare, eyes are strained in order to see and discern the characters appearing on the display screen. Another aspect of reflective glare involves objects which can be seen on the screen in addition to the screen image. So-called veiling reflections require the eyes to continuously filter out the reflected image from the screen image. On the whole, reflective glare is generated by light sources outside of the screen, such as behind, above or next to the operator. Needless illumination is bounced onto the monitor, and the light from these unexpected sources enhances the likelihood that CVS will result. 
     It has been determined that eye strain generally associated with CVs, and the associated symptoms such as burning or tired eyes, blurred vision, loss of focus and headaches, can be significantly reduced by systems of the present invention which incorporate indirect lighting for illuminating a task area. When properly utilized, indirect lighting minimizes both direct glare and reflective glare on the video display tube. Uniform glare and veiling reflections issues are significantly controlled. By reducing the external illumination of the display screen while still adequately lighting the task area, eye strain symptoms are reduced, and blinking frequency rates are more naturally increased. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, task lighting is provided which does not produce glare, but instead creates a reflected glow of indirect lighting of the immediate workspace. More particularly, an indirect task light is provided for monitors, video display tubes, and the like. The task light system incorporates a source of light which is directed upwardly toward a visor member which receives light rays from the light source. A reflective surface of this visor member reflects the light rays generally downwardly in a ray pattern which avoids any substantial direct illumination of the display screen by these light rays. Generally speaking, the light rays are reflected in an array which defines an illumination pathway having rays which are generally parallel to the display screen, as well as rays which extend away from the computer screen when viewed in a downward direction. No rays are directed toward the screen by the system. 
     It is accordingly a general object of the present invention to provide an improved indirect illumination task light for computer monitors, video display tubes, display screens and the like. 
     Another object of the present invention is to provide an improved task light which shines only reflected, indirect light onto a task area positioned generally in front of a monitor display screen and the like. 
     Another object of this invention is to provide an improved task light which results in increased blinking frequency of the eyes of a user of equipment such as a computer having a display screen which is viewed for long periods of time by the user. 
     Another object of the present invention is to provide task lights which successfully address eye strain concerns often associated with Computer Vision Syndrome. 
     Another object of this invention is to provide an integral component of a work station which provides task lighting that does not produce glare on a display screen at a task area location. 
     Another object of the present invention is to provide an improved task light system which is easily mountable onto the top panel of a computer monitor or the like and which indirectly lights a task area in front of the monitor. 
     Another object of the present invention is to provide an improved task light system which is incorporated within the casing of a computer monitor, video display tube or the like and that provides indirect illumination of a task area in front of the monitor. 
     Another object of the invention is to provide a task light system which avoids directly illuminating the display screen at the workstation. 
     These and other objects, features and advantages of the present invention will be apparent from and clearly understood through a consideration of the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the course of this description, reference will be made to the attached drawings, wherein: 
     FIG. 1 is a perspective view of an embodiment of a task light according to the invention, shown in combination with a computer monitor; 
     FIG. 2 is an elevational side view schematically illustrating certain aspects of the combination of FIG. 1; 
     FIG. 3 is a side elevational view of a task light as generally shown in FIG. 1 in combination with a different embodiment of computer monitor; 
     FIG. 4 is a cross-sectional view of a shade or visor member as generally shown in FIG. 1, illustrating pivoting movement thereof; 
     FIG. 5 is a cross-sectional view of a shade or visor member as generally shown in FIG. 1, illustrating sliding vertical movement thereof; 
     FIG. 6 is a generally schematic detail view of the task light as generally shown in FIG. 1; 
     FIG. 7 is a top plan view of the task light of FIG. 1, shown with the visor assembly cut away; 
     FIG. 8 is a top plan view as in FIG. 7, illustrating another embodiment of the lens and internal reflector of the base assembly; 
     FIG. 9 is a top plan view of the task light of FIG. 1; 
     FIG. 10 is a front elevational view of the task light of FIG. 1; 
     FIG. 11 is a rear elevational view of the task light of FIG. 1; 
     FIG. 12 is a perspective view illustrating a task light incorporated into the casing of a computer monitor; and 
     FIG. 13 is a cross-sectional view, partially broken away, along the top portion of the monitor of FIG. 12, further showing the task light in generally schematic elevation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of a task light according to the invention is generally illustrated at 21 in FIG. 1. Task light 21 is shown mounted on, and in combination with, a computer monitor, generally designated at 22. A detailed description of the monitors illustrated herein is not provided in view of the general knowledge of such devices to those of ordinary skill in the art. Monitor 22 is also intended to illustrate any other devices having a video display tube having a screen such as the display screen 23 which is illustrated. 
     Task light 21 includes a base assembly 24 and a shade or visor member 25 suspended above the base assembly by a frame unit 26. Also included in this illustrated embodiment is a bracket assembly 27. Other suitable suspensions and assemblies can take forms other than those explicitly illustrated in the drawings. 
     Referring more specifically to the illustrated bracket assembly 27, this has an adjustability feature which is useful in accommodating the task light 21 to a variety of different monitors. For example, each of monitor 22 of FIG. 1 and 22a of FIG. 2 have a generally horizontal top surface. With these types of monitors, the bracket assembly is typically adjusted such that bottom surface 31 of the bracket assembly 27 is generally horizontal and substantially perpendicular to the frame unit 26 when viewed from the side as in FIG. 2 and FIG. 6. 
     With further reference to FIG. 6, bottom surface 31 includes an indent within which is positioned a mounting member such as illustrated double-sided tape 32. Such mounting member securely fastens the base assembly 24 and thus the task light to an upper surface of the monitor. As can be generally seen in FIG. 3 and in FIG. 6, the base assembly is adjustable such that the bottom surface 31 is not perpendicular, but instead is angularly offset with respect to, the frame unit 26, as can be seen in FIG. 3. 
     In the illustrated embodiment, a bottom bracket 33 is slidably secured along an arcuate path with respect to a bottom boss 34. A suitable securement assembly holds the arcuate position of the bottom bracket 33 which is selected with respect to the bottom boss 34. The illustrated securement assembly includes a bracket 35, a sleeve 36, a screw 37, and a threaded cap 38 for receiving and holding the bolt. Once the bolt is loosened, the bottom bracket 33 can be swung to the position desired, after which the assembly is tightened down in place. 
     FIG. 4 illustrates the tiltability of the visor member 25 by virtue of its being rotatably mounted with respect to the frame unit 26. Any suitable pivot mounting assembly which will accommodate desired tilting of the visor member 25 can be utilized. Illustrated pivot 41 supports the shade by downwardly depending ears 42, which receive a pivot shaft 43 projecting from a projecting mount 44 of a bushing 45. This feature allows the user to adjust the ray pattern developed by the inside surface of the visor member 25 as it reflects light emanating from the base assembly 24, as generally discussed herein. This permits adjustment for accommodating the needs of different users, such as user height, and height and placement of task areas and seating devices. 
     FIG. 5 illustrates vertical adjustment which is available in accordance with this embodiment. Each bushing 45 is mounted along each vertical length of the frame unit 26. In order to prevent visor member 25 from moving too close to the light source within the base assembly 24, a stop 46 is preferably included. 
     With further reference to the base assembly 24, a lens 51 is provided over a light-passing opening 52 within a casing 53. As illustrated, vents 54, 55 can be included for dissipating heat out of the base assembly. Typically, the lens 51 will be substantially transparent so that light emanating from light source 56 will pass out of the casing 53 through the light-passing opening 52. 
     It will be noted that the front portion 57 of casing 53 has a height greater than rear portion 58 of the casing. As can be seen from various Figures, including FIG. 6, FIG. 10 and FIG. 11, this unsymmetrical construction results in the light-passing opening 52 being oriented generally rearwardly, as well as upwardly. Among other effects, this unsymmetrical top casing avoids unwanted direct illumination toward the front of the task light, while also shielding the user&#39;s eyes from light emanating directly from the opening 52. 
     Light source 56 can be any of a variety of sources. The illustrated one is a fluorescent source, controllable by off-on switch 59 or other suitable means. As schematically illustrated in FIG. 2 and in FIG. 6, some of the light rays from this light source 56 remain within the casing 53. Some of the light reflects off of a back or inside reflector 61. 
     Back reflector illustrated in FIG. 7 has a generally smooth reflective surface, while reflector 61a of FIG. 8 has a rough or hammertone reflective surface. Another reflector or reflective surface can be provided within the visor member 25, as generally illustrated at 62 in FIG. 6. These reflectors can be made of reflective foil which is adhesively applied or plated by suitable means such as electroless deposition. Plated polymer reflector members can be made of polymers such as polycarbonate, polyurethane and the like, such as those exhibiting a mirror finish. A non-metallic polycarbonate reflector member having a composition as generally known to those skilled in the art can be utilized. 
     It will be appreciated that the visor 25 is functionally off center in the illustrated embodiment. In a general sense, this facilitates the indirect lighting effect provided by the invention at the task area in front of the display screen, while simultaneously permitting ambient light to emanate from the rear of the task light and of the computer work station. Both of these functions now are more specifically described, especially with reference to FIG. 2, FIG. 6 and FIG. 13. 
     Light rays which pass through opening 52 but not through the rest of the casing 53 are schematically illustrated. A forwardmost ray 63 reflects from visor reflector 62 in a direction which is generally vertical and generally parallel to display screen 23. Another illustrated ray 64 is somewhat more vertical after it leaves the visor member 25. A plurality of rays form the ray pattern which is generally illustrated lights a task area 65 extending in front of the monitor. A generally rearwardmost ray 66 which is reflected by the visor reflector 62 reflects the light within the generally downwardly oriented ray pattern, but at a less vertical angle than ray 64. These rays combine to form the illustrated light array which extends from a generally vertical orientation in front of the display screen 23 to an extent at which the ray pattern gradually increases forwardly in the downward direction. This light pattern has a rough overall appearance of a generally triangularly shaped column of light in front of the monitor and which illuminates the task area. 
     Light rays such as ray 67 do not impinge upon the visor member 25, but instead provide direct lighting toward the rear of the task light in order to provide ambient lighting. Ambient lighting can be beneficial in reducing eye strain by lessening the contrast between the display screen and the environment around the monitor, but in a way which does not cause reflective glare at the display screen 23. 
     Referring now to the embodiment illustrated in FIG. 12 and FIG. 13, the task light of this embodiment, generally designated 121, can have an overall structure similar to that of the previously discussed embodiments. It will be appreciated that other structures can be substituted. In this particular illustrated embodiment, the task light 121 is integrally positioned within an upper portion of case 122 of this monitor 22c. Light source 156 is shown positioned within the base 122, with light from it passing through opening 152 and through lens 151. A casing 153 is schematically illustrated. It will be appreciated that a suitable casing can be provided which is a more integral part of the monitor case 122, and this case 153 is provided for illustrative purposes to indicate how the basic concept of the invention can be implemented in a task light arrangement which is built into the monitor itself. Illustrated visor member 125 performs functions along the lines of those discussed elsewhere herein. Visor member 125 is illustrated as being adjustably supported along the frame unit 126 as generally discussed. 
     The embodiment illustrated in solid lines provides only the downwardly (and somewhat forwardly) directed ray pattern for illuminating the task area in front of the monitor 22c, as generally discussed elsewhere in connection with rays 63, 64 and 66. Illustrated in phantom is an ambient light passageway 168 which can be provided when it is desired to permit backlight, schematically illustrated by ray 67, from emanating out of the monitor in order to provide some ambient lighting. 
     Photometry tests were conducted which illustrate the effectiveness of the indirect task lighting achieved by the set up generally illustrated in FIG. 2. Light sensors were located in a patterned array so as to measure the quantity of light both on the screen of a computer monitor and the soft indirect light at the task area in front of the computer. A task light having a fluorescent lamp rated at 900 lumens was positioned atop a 17 inch monitor. The task area lit was a desk top providing a 36 inch by 18 inch workspace in front of the monitor. Several runs were conducted. The amount of light detected on the computer screen was at very low levels, ranging between about 1.5 foot candles to about 3 foot candles. Further adjustment of the visor revised the maximum foot candles on the screen to about 2.3 foot candles. 
     At the same time, the light at the indirectly lit task area was an absolute minimum of 3 foot candles at the edges of the 36 inch space being lit from the light source which was 6 inches in length. Generally, the light intensity increased more toward the center of the task area. For example, within approximately the central 18 inches of the task area, the illumination amounts measured at the same time as the computer screen measurements noted above ranged between about 8 foot candles and about 18 foot candles, discounting the fringes of this task area. 
     It will be understood that the embodiments of the present invention which have been described are illustrative of some of the applications of the principles of the present invention. Various modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.