Abstract:
A display for a vehicle includes an indicator such as a pointer or needle. The display is configured such that (1) the position of the indicator is responsive to, and thus indicative of, a first measurable vehicle characteristic; and (2) the appearance of the indicator is responsive to, and thus indicative of, a second measurable vehicle characteristic. In a preferred embodiment, the first measurable characteristic is vehicle speed and the second measurable characteristic is engine speed so that the display functions as a combined speedometer and tachometer. A corresponding method is also provided.

Description:
TECHNICAL FIELD  
       [0001]     This invention relates to vehicle displays having an indicator, the position of which indicates the value of a first measurable vehicle characteristic and the appearance of which is indicative of the value of a second measurable vehicle characteristic.  
       BACKGROUND OF THE INVENTION  
       [0002]     Vehicles typically include a plurality of displays for conveying information about the vehicle, including its components, to a driver. For example, vehicles typically include a speedometer that indicates the speed of the vehicle to a driver. Prior art speedometers are typically gauges with markings expressing a range of vehicle speeds and a movable pointer. The position of the pointer with respect to the markings indicates vehicle speed. Vehicles often employ a tachometer to indicate engine speed. Prior art tachometers are also typically gauges with markings and a movable pointer.  
         [0003]     Modern vehicles convey a significant amount of information to a driver regarding the status of the vehicle and its component systems. However, informational displays take up limited space in an instrument panel and limit the design of the cockpit.  
       SUMMARY OF THE INVENTION  
       [0004]     A display for a vehicle having at least two measurable characteristics is provided. The display includes a movable indicator; the position of the indicator is responsive to, and thus indicative of, a first measurable vehicle characteristic. The appearance of the indicator is responsive to, and thus indicative of, a second measurable vehicle characteristic different from the first measurable vehicle characteristic. The display of the invention conveys the same amount of information as two prior art displays. For example, the first measurable characteristic may be vehicle speed and the second measurable characteristic may be engine speed. The display would thus function as both a speedometer and a tachometer, eliminating the need for separate tachometer and speedometer gauges. The elimination of separate tachometer and speedometer gauges improves upon the prior art by (1) providing more room in an instrument panel for other informational displays or to increase the size of displays, and (2) enabling smaller instrument panels compared to the prior art.  
         [0005]     In an exemplary embodiment, a first segment of the indicator alters the color it displays in response to the engine operating above a first predetermined speed, and a second segment of the indicator adjacent to the first segment alters the color it displays in response to the engine operating above a second predetermined speed. The indicator would then function like a bar graph, where the quantity of adjacent segments whose displayed color has been altered increases with engine speed.  
         [0006]     A corresponding method for indicating values of a plurality of measurable vehicle characteristics is also provided. The method includes moving an indicator in response to a first vehicle characteristic, and changing the appearance of the indicator in response to the second vehicle characteristic.  
         [0007]     The above features and advantages, and other features and advantages, of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a schematic partial cutaway side view of a vehicle including an engine;  
         [0009]      FIG. 2  is a schematic front view of a display with a pointer, the position of which indicates the speed of the vehicle of  FIG. 1 , and the appearance of which indicates the speed of the engine of  FIG. 1 ;  
         [0010]      FIG. 3  is a schematic front view of the display of  FIG. 2  with the pointer having a plurality of segments colored differently than in  FIG. 2 ; and  
         [0011]      FIG. 4  is a schematic front view of the display of  FIGS. 1 and 2  with the pointer having yet more segments differently colored. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]     Referring to  FIG. 1 , a vehicle  15  having an engine  19  is schematically depicted. The engine  19  has a rotatable crankshaft  23 . An instrument panel  27  in a passenger compartment  29  informs a driver (not shown) of various operating states and conditions of the vehicle, including vehicle velocity with respect to the surface on which the vehicle is traveling (vehicle speed), and the angular velocity of the crankshaft  23 , referred to hereinafter as “engine speed.” 
         [0013]      FIG. 2  schematically depicts a display  31  on the instrument panel  27  of  FIG. 1 . The display  31  includes markings  35 , such as numbers, to represent various vehicle speeds. The display  31  also includes an elongated pointer  39 , or needle, movable with respect to the markings  35 ; the pointer  39  functions as an indicator whose position with respect to the markings  35  is indicative of vehicle velocity.  
         [0014]     More specifically, the pointer  39  is rotatable about axis A. When the vehicle is at rest, i.e., vehicle velocity is zero, the pointer is in an initial position (shown in phantom at  39 ′) in which the pointer points to a marking representing zero. The angular displacement of the pointer from the initial position is directly proportional to vehicle speed. The pointer  39  indicates that the vehicle speed is approximately 20 miles per hour (mph) in  FIG. 2 .  
         [0015]     The appearance of at least a portion of the pointer  39  is variable in response to engine speed so that the appearance of the pointer  39  provides some indication of engine speed to a driver. In the embodiment depicted, the pointer  39  has seven portions, or segments  43 A-F, that alter appearance in response to engine speed. The segments are spaced along a portion of the length of the pointer  39 . In the context of the present invention, the “bottom” of the pointer  39  is that portion of the pointer proximate to the axis A of rotation. The “top” of the pointer is that portion of the pointer at the distal end from the axis A. Accordingly, a segment that is “higher” than another segment is closer to the “top” of the pointer. Segment  43 A is the segment most proximate to the axis A of rotation of the pointer; segment  43 F is the segment most distant from the axis A. Segments  43 B-E are arranged between segment  43 A and segment  43 F such that segment  43 B is higher than segment  43 A, segment  43 C is higher than segment  43 B, segment  43 D is higher than segment  43 C, and segment  43 E is higher than segment  43 D.  
         [0016]     Each of segments  43 A-F is, i.e., displays, a respective initial color. In the present embodiment, the respective initial color of each segment is white. However, within the scope of the claimed invention, the initial color of each segment may or may not be the same. Each segment  43 A-F changes or alters the color it displays from its respective initial color in response to the engine speed exceeding a predetermined amount. To avoid the need for color drawings, the different colors are schematically represented by different cross-hatching patterns in the Figures. The predetermined engine speed amount at which a segment changes color is dependant upon the distance of the segment from the axis A: the farther a segment is from the axis, the higher the predetermined engine speed at which the segment displays a color different from its respective initial color. In the context of the present invention, a change in color of a segment includes a change in hue, saturation, or brightness of the segment. A change in color may be the result of changes to the reflective characteristics of the segment, illumination of the segment (i.e., light emitted from or through the segment), etc.  
         [0017]     Segment  43 A has changed the color it displays from its initial color to green in  FIG. 2  to indicate that the engine is operating at a speed greater than a first predetermined amount. For example, the first predetermined amount may be the engine&#39;s idle speed so that segment  43 A is always green when the engine is running.  
         [0018]     Referring to  FIG. 3 , wherein like reference numbers refer to like components from  FIG. 2 , segment  43 B has changed from its initial color to green to indicate that the engine speed exceeds a second predetermined amount greater than the first predetermined amount, such as 2500 rpm. Segment  43 C has changed from its initial color to yellow to indicate that the engine speed exceeds a third predetermined amount greater than the second predetermined amount, such as 3500 rpm. Segments  43 D-F are their respective initial colors, indicating that the engine is operating between the third predetermined amount and a fourth predetermined amount at which segment  43 D changes to a color different from its initial color. The pointer  39  has moved from its position in  FIG. 2  to indicate that the vehicle speed is approximately 30 miles per hour.  
         [0019]     Referring to  FIG. 4 , segment  43 D has changed from its initial color to yellow to indicate that the engine is operating at a speed greater than the fourth predetermined amount. Segments  43 E and  43 F have changed from their respective initial colors to red to indicate that the engine is operating above a fifth and a sixth predetermined amount, respectively.  
         [0020]     It may be desirable for the display to include numerical markings (not shown) on the pointer to provide more information to a vehicle driver. For example, a number indicating the predetermined engine speed at which a segment changes color may be adjacent to the segment.  
         [0021]     The appearance of the pointer  39  indicates engine speed in two ways. First, the quantity of segments that have changed from their respective initial colors reflects engine speed. If the upper segment, i.e., segment  43 F, changes color when the engine is operating at or near its maximum capacity, then a driver can estimate the percentage of the maximum speed at which the engine is operating by the percentage of segments that have altered color.  
         [0022]     Second, the specific colors displayed on the pointer indicate the engine speed to a driver. In the embodiment depicted, only green is displayed when the engine speed is at or below the third predetermined amount. Similarly, only yellow and green are displayed when the engine speed is at or below the fifth predetermined amount. Red is displayed only when the engine speed is higher than the fifth predetermined amount.  
         [0023]     Although the appearance of the pointer in the preferred embodiment indicates engine speed in two ways, i.e., by the quantity of segments that have changed from their initial color, and by the specific colors displayed, the appearance of the pointer may also indicate engine speed in only one way within the scope of the claimed invention. For example, the color displayed by only one portion of the pointer may change in response to engine speed; the one portion may be green when the engine speed is in a low range, yellow in a higher engine speed range, and red when the engine speed is above the redline.  
         [0024]     In the embodiment depicted, the position of the pointer indicates vehicle speed and the appearance of the pointer indicates engine speed. However, within the scope of the claimed invention, the display could indicate any two measurable characteristics of the vehicle. For example, the display may be configured such that the position of the pointer indicates vehicle speed, and the appearance of the pointer indicates fuel level.  
         [0025]     The display  31  may take a variety of forms within the scope of the claimed invention. For example, the display may be mechanical, with the markings  35  printed on a dial face, and the pointer may be connected to a geared stepping motor. LEDs may form part of the pointer, i.e., placed on or within the pointer; the LEDs would be controlled to selectively illuminate, and thereby cause segments of the pointer to change color in response to engine speed. Alternatively, and within the scope of the claimed invention, a “pointer” or “indicator” may be an image of a pointer or indicator, such as on a computer-controlled liquid crystal display (LCD). Similarly, “markings” may also be images on a screen.  
         [0026]     While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.