Abstract:
An instrument display for a vehicle comprises a first light guide ( 14 ) in communication with a first light source ( 18 ). (FIG.  1 A). The first light guide ( 14 ) directs light to a first instrument mark ( 22 ). A second light guide receives light from a second light source ( 34 ). The second light guide ( 26 ) is spaced from the first light guide ( 14 ) and directs light to a second instrument mark ( 24 ). A support ( 42 ) connects the first light guide ( 14 ) and the second light guide ( 26 ) and limits light transmission between the first light guide ( 14 ) and the second light guide ( 26 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to U.S. Provisional Patent Application Serial No. 60/341,534 filed on Dec. 17, 2001 and U.S. Provisional Patent Application Serial No. 60/336,247 filed on Nov. 15, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to an instrument cluster for a vehicle.  
           [0003]    Instrument clusters for a vehicle are typically located on a vehicle dashboard and may include a speedometer, tachometer, engine condition indicator, ABS braking indicator, and other vehicle marks. This cluster of display marks may have lighting to illuminate each mark, when appropriate. For example, the ABS braking mark may be illuminated when the vehicle is undergoing ABS braking. In the past, this lighting was provided by individual lamps that illuminate each indicator of the dashboard. However, this type of lighting takes up significant space and requires a high voltage circuit to supply current to each of the lamps. The high voltage further requires insulation to protect against shock, thereby increasing the cost and size of the instrument cluster.  
           [0004]    Recently, it has become more common to use optical light guides to bring illumination to each of the display marks of the instrument cluster. However, each mark requires its own light guide and light source so that each individual mark may be separately illuminated. A typical instrument cluster has 32 separate indicators that require such lighting. Each light guide associated with each indicator is painstakingly assembled into the cluster one at a time. Consequently, a great deal of time and effort is required to individually piece the light guides into the instrument cluster.  
           [0005]    In addition, existing light guides for an instrument display such as a dial require the use of a dial appliqué. The dial appliqué is a film of plastic having instrument display marks, such as the hash marks of a speedometer gauge, the numbers for the gauge, vehicle telltales, and other marks. Most of the dial appliqué is opaque except for the illuminated portions. A light guide used with the dial appliqué, such as the light guide for the speedometer gauge, may illuminate large portions of the dial appliqué rather than just the marks. Accordingly, existing instrument displays waste lighting energy.  
           [0006]    A need therefore exists for a thin instrument cluster that avoids the complexity, inefficiency, and size of existing lighting systems.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention comprises a light guide that transmits light from a light source to an instrument display mark. In contrast to existing systems, however, adjacent light guides are attached to each other by a support that holds them together for quick assembly into an instrument cluster. The support may be opaque to prevent the transmission of light between individual light guides. In this way, rather than have individual light guides assembled one at a time into an instrument cluster, the inventive display employs a cluster of light guides with each individual light guide attached to an adjacent light guide by the opaque support, thereby allowing a single unit to be assembled into the instrument cluster rather than individual pieces. In addition, another feature of the invention eliminates the need for a separate display appliqué by using the instrument display marks as graphical structures to direct light from the light guide to a vehicle occupant. The resulting instrument display employing these features is thin, energy efficient, and easy to assemble.  
           [0008]    Accordingly, the inventive display comprises a first light guide with a first light source directing light to a first instrument display mark. A second light guide with a second light source is spaced from the first light guide and directs light to a second instrument display mark. A support connects the first light guide to the second light guide and limits transmission of light between the two light guides. This support permits one light guide to be illuminated without illuminating the neighboring light guide.  
           [0009]    A control unit, such as a printed circuit board, may activate each light source. The light sources may be mounted to the printed circuit board and may comprise light emitting diodes. Structure on the light guide may be used to redirect light from the light guide to illuminate the instrument display mark. The structure may comprise micro lenses. The instrument mark may absorb the light and form a dark shape, letter, or figure on a light background.  
           [0010]    Another feature of the invention uses each instrument display mark as a graphical structure to direct light from the light source. A light source provides light to a light guide. The structure shaped in the form of the instrument mark then directs light from the light guide to a viewer of the instrument display. The graphical structure may comprise pyramidal shaped structures formed in a shape of the instrument mark. The instrument mark may also comprise a painted or etched mark on the light guide. This feature allows the elimination of instrument panel display appliqué and results in greater energy efficiency.  
           [0011]    The resulting inventive display permits the instrument cluster to be almost as thin as the light guide. In addition, each individual light guide may be separately illuminated without significant effort taken to piece each light guide into the instrument cluster. Indeed, the collection of light guides for each mark may comprise a single unit that may be simply assembled into the instrument cluster. Moreover, the inventive light guide uses less energy than existing systems. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:  
         [0013]    [0013]FIG. 1 illustrates the inventive instrument display.  
         [0014]    [0014]FIG. 1A illustrates light guides, supports and marks of the inventive display of FIG. 1.  
         [0015]    [0015]FIG. 2 illustrates a close up alternative view of light guides of FIGS. 1 and 1A.  
         [0016]    [0016]FIG. 3 illustrates a side view of the inventive display of FIG. 1.  
         [0017]    [0017]FIG. 4 illustrates a side view of the inventive display of FIG. 1.  
         [0018]    [0018]FIG. 5 illustrates a driver&#39;s view of an inventive display in which the marks are formed as part of the light guide.  
         [0019]    [0019]FIG. 6 illustrates a top view of the inventive display of FIG. 5.  
         [0020]    [0020]FIG. 7 illustrates a side view of an inventive display using pyramidal structures.  
         [0021]    [0021]FIG. 8 illustrates a side view of an inventive display using painted marks.  
         [0022]    [0022]FIG. 9 illustrates an inventive display using etched marks.  
         [0023]    [0023]FIG. 10 illustrates the path of light of the inventive display. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    [0024]FIG. 1 illustrates an exploded view of the inventive display  10 , an instrument cluster for a motor vehicle. Back cover  101  provides support for movements  104 , which are associated with pointers  130 . Control unit  50 , here a printed circuit board, has clusters of light emitting diodes, which are controlled by control unit  50  to respond to various vehicle conditions as known. Light emitting diodes  108  when assembled to light housing  112  protrude through light housing  112  and provide light to light guides associated with light guide cluster  116 . Light from light emitting diodes  108  accordingly illuminates light guide cluster  116 . Light housing  112  provides the background for light guides  116  and may be dark or light depending on the desired background effect. Liquid crystal display  120  may also be associated with instrument display  10  and be illuminated by a light guide from light guide cluster  116 . Dial appliqué  124  has various marks, such as fuel level indicator, speedometer, tachometer, engine light indicator and other known vehicle display marks. A light guide from light guide cluster  116  illuminates each of these display marks. Each light guide may be individually illuminated so that each individual mark on dial appliqué  124  is separately illuminated upon the appropriate vehicle condition.  
         [0025]    As shown in FIG. 1A, first light guide  14  receives light from first light source  118 , a series of light emitting diodes, along the arrows shown. This light is transmitted through light guide  14 , which is made of known translucent material. First instrument mark  22 , here a speedometer dial, is placed in proximity to first light guide  14  and illuminated by light traveling through light guide  14  by first light source  18 . In addition, second light guide  26  has second light source  34 , a single light emitting diode, shining light along the arrow shown. Second light guide  26  is in proximity to second instrument mark  24 , here check engine indicator  54 . Light from second light source  34  illuminates second light guide  26 , which then illuminates second instrument mark  24 . Moreover, as shown, third light guide  30  is located in proximity to third instrument mark  25  here, an ABS braking system indicator, and is illuminated by light from third light source  38 , also a liquid emitting diode, as shown. Second light source  34  and third light source  38  are controlled by control unit  50  to illuminate when particular vehicle conditions exist. For example, in the event engine is malfunctioning, second light source  34  may illuminate second light guide  26  and second instrument mark  24 , a check engine indicator. When engine conditions do not exist that require such lighting, second instrument mark  24  will not be illuminated. In this way, only relevant information about the vehicle may be relayed when needed. In addition, first instrument mark  22 , here a speedometer, may be illuminated when nighttime driving conditions exist. First instrument mark  22 , second instrument mark  24  and third instrument mark  25  may each be required to be separately or collectively illuminated under different conditions. Accordingly, it is desirable to illuminate these light guides only when such conditions exist to avoid confusing the driver. Therefore, each light guide should not only have its own light source as shown but should avoid transmitting light to an adjacent light guide. Light guides  14 ,  26  and  30  are thus spaced far enough from each other so that light within each of these guides is not transmitted to the adjacent guide.  
         [0026]    Thus, as shown in FIG. 2, each separate mark requires its own light guide.  
         [0027]    Given the great number of marks, a fair number of light guides are located in close proximity to each other within instrument display  10 . An arrangement with many individual light guides is difficult to assemble into instrument display  10  unless supports are used to connect one light guide to the other. As shown in FIG. 1A, light guide  14  is connected to second light guide  26  by support  42  while second light guide  26  is connected to third light guide  30  by support  46 . Supports  42 ,  46  and others like it are used to create a single unit as shown in FIG. 2. Moreover, to prevent light guide  14  from transmitting light to light guide  26 , support  42  is preferably made of light absorbing material, such as ABS black plastic, so that light is not transmitted through support  42 . In this way, light guides may be connected to each other without creating the potential for the transmission of light from one light guide to the next.  
         [0028]    As shown in FIG. 2, light guide cluster  116  presents a single unit that maybe quickly assembled as part of instrument display  10 . Light guide cluster  116  may be easily created from known two-shot molding techniques. Referring back to FIG. 1, light guide cluster  116  may be aligned with dial appliqué  124  so that each individual light guide is aligned with its associated mark on dial appliqué  124 . Light guide cluster  116  may also provide light to liquid crystal display  120 , which is held in place to instrument display by bracket  130 . Mask  134  provides a protective covering for instrument display  10 .  
         [0029]    [0029]FIG. 3 illustrates a cross-sectional portion of instrument display  10  of FIG. 1. As shown, control unit  50 , a printed circuit board, supports and controls light emitting diode  136  which shines light in the direction of arrow A through light guide  127 . Micro lens structure  138  on the surface of light guide  127  serves to redirect light from light guide  127  along arrow B. Micro lens structure  138  may be applied to light guide  127  through known techniques. Light traveling along arrow B is transmitted through liquid crystal display  120 , which may provide additional feedback on the vehicle&#39;s condition. FIG. 3 also illustrates the reduced thickness of the inventive display. Indeed, instrument display  10  may be as thin as 6 millimeters.  
         [0030]    [0030]FIG. 4 illustrates a cross-sectional view of another portion of instrument display  10 . Here, pointer assembly  140  serves to provide a pointer for a vehicle mark, such as a speedometer or tachometer. Light guide  14  is supported on control unit  50 . In addition, third light guide  30  is adjacent to first light guide  14  although separated by a portion of light housing  112 . Dial appliqué  124  and control unit  50  serve to sandwich in place first light guide  14 , third light guide  30  and other light guides of light guide cluster  116 . Third light source  38 , here a light emitting diode, serves to illuminate third instrument mark  25  on dial appliqué  124 . Dial appliqué  124 , as shown in FIG. 1A, may comprise thin plastic material with vehicle marks marked on the surface. Movement  148  serves to move pointer  140 .  
         [0031]    [0031]FIGS. 1 through 4 illustrate inventive display  10  using dial appliqué  124  to provide a surface for various vehicle marks. Micro lens structure, such as micro lens structure  138 , serve to direct light through dial appliqué  124 . Inventive display  10  is much easier to manufacture and assemble than existing instrument displays.  
         [0032]    Another feature of the inventive display uses instrument marks themselves to redirect light through the light guides. FIGS. 5 through 10 illustrate this particular inventive feature. As shown in FIG. 5, light sources  150 , such as light emitting diodes, serve to direct light through light guide  154 . As known, pointer  158  is connected to a movement to rotate along the circular path of light guide  154 . Marks are placed on light guide  154  rather than on a separate dial appliqué as shown in FIGS.  1 - 4 .  
         [0033]    [0033]FIG. 6 illustrates the instrument display of FIG. 5 from a top view. Movement  166 , which rotates pointer  158 , is also shown. As seen in this figure, graphical structure  162 , here a hash mark to delineate portions of a dial such as a speedometer, are placed on the back of light guide  154  as shown. Graphical structure  162  may comprise paint on surface of light guide  154 . Light transmitted through light guide  154  along arrow C is scattered and reflected by graphical structure  162  with a portion of the light traveling along arrow D, toward a viewer of the display.  
         [0034]    [0034]FIG. 8 shows light guide  170  with graphical structure  86 , painted portions, on one side of light guide  170 . However, these same surfaces may be placed on the opposite side of light guide  170  as shown by the dashed lines. Preferably, light guide  170  has beveled edges  78  to help retain light within light guide  170 .  
         [0035]    [0035]FIG. 7 illustrates graphical structure  62  that serves to redirect light. Here, pyramidal shaped structures  82  are formed together in the shape of a graphical structure  62 , such as a hash mark, a figure, a symbol, a check engine light or other graphic on light guide  174 . As shown in FIG. 10, light in the form of light beams  190 ,  192  from light source  200  is transmitted through light guide  174  generally along arrow E. Light beam  190  is directed to pyramidal shape structure  82  on light guide  174 , which then serves to redirect light by reflection across light guide  174  generally along arrow F toward a viewer, such as a vehicle driver  194  as schematically shown. Light beam  192  continues to travel through light guide  174  to, say, another graphical structure  62 , such as another hash mark.  
         [0036]    Because portions of light continue to pass out of light guide  174 , the intensity of light decreases. To increase illumination, light source  204  is employed and communicate light through light guide  174  as well. Here, light beams  194  and  196  are transmitted through light guide  174 . Light beam  196  passes out of light guide  174  to pyramidal structure  82  and is reflected across light guide  174  toward driver  194  generally along arrow F. In this way, the intensity of illumination of graphical structure may be maintained.  
         [0037]    [0037]FIG. 9 illustrates the use of etchings  90  as graphical structure on light guide  178 . Etchings  90  serve to direct light traveling through light guide  178  toward a person viewing the display. Other graphical structures such as holograms, micro holes, or other light redirecting material or structure may be employed to accomplish the same objectives as disclosed. As further shown in FIG. 9, background mat  182  may be placed next to light guide  178 , opposite the side of viewer of the display. Background mat  182  may be a film and may be dark or light to provide positive or negative background as known.  
         [0038]    The aforementioned description is exemplary rather that limiting. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed. However, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. Hence, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For this reason the following claims should be studied to determine the true scope and content of this invention.