Abstract:
A display for measured quantities can include a dial plaque with at least one set of indicia spaced around the plaque to indicate the measured quantities. An optical device can be mounted on a shaft within a perimeter of the dial plaque at a location surrounded by the indicia. The optical device can redirect an incident light beam onto the area of the set of indicia. A motor can turn the shaft to rotate the optical device through three-hundred-sixty degrees about an axis of rotation centered on the shaft. Apparatus can be provided for sensing the shaft rotating angular position. A light source can project a light beam on the optical device through the axis of rotation, such that a virtual pointer is generated.

Description:
FIELD 
     The present disclosure relates to analog displays for measured quantities such as automotive speed, coolant temperature, fuel level and the like, and more particularly to an instrument cluster comprising a display field and having no conventional meter movements, pointers or other components susceptible to inertial effects. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Automotive instrument clusters typically comprise large discreet display areas for a speedometer and a tachometer, and a number of smaller displays for coolant temperature, oil pressure, oil temperature, fuel level and the like. Arranged within and around the cluster are other indicators showing low fluid level conditions, turn signal operation, emergency light blinkers and so forth. The analog displays within the display fields can be provided by means of devices having electromechanical movements for causing angular sweep of a needle across the display field. In many systems, low values of the measured quantity are typically displayed at the left side of the display field, high values at the right side of the display field, and intermediate values at incrementally spaced locations between the left and right sides. 
     It has become increasingly more difficult to attach cables, wires and other devices to the back side of the instrument cluster to provide all of the various desirable displays while retaining flexibility and accessibility. Moreover, all of the meter movements are difficult to calibrate and to maintain in calibration. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     A display for measured quantities can include a dial plaque with at least one set of indicia spaced around the plaque to indicate the measured quantities. An optical device, such as a mirror, can be mounted on a shaft within a perimeter of the dial plaque at a location surrounded by the indicia. The mirror can have a curved reflector surface with a predetermined radius. A motor can turn the shaft to rotate the mirror through three-hundred-sixty degrees about an axis of rotation centered on the shaft. Means can be provided for sensing the angular position of the shaft rotating. A light source can project a light beam on the reflector surface of the mirror through the mirror axis of rotation, such that a virtual pointer is generated. 
     According to other features, the optical device can enable the redirected secondary beam to be aimed at the indicia for a three-hundred-sixty degrees scan around the plaque as the optical device is rotated. A controller can receive signals representing the measured quantities. The controller can monitor the angular position of the shaft provided from signals from the sensing means and coordinate on/off of the light source based on the derived angular position. 
     According to additional features, the dial plaque can define multiple sets of indicia at corresponding display regions. Each set of indicia can correspond to a distinct measured quantity of the measured quantities. A unique illumination marker can be identified concurrently on each set of indicia by the light beam that is redirected by the optical device. According to one example, the motor can be located in a position intermediate of the optical device and the light source. In one configuration, the shaft can define a cannulation and the light source can project the light beam through the cannulation. According to one example, the optical device is a mirror. The mirror can define a body having an outer boundary wherein the reflector surface is formed within the outer boundary of the body. According to another example, the mirror can be located in a position intermediate of the motor and the light source. The light source can be a laser light source, a focused LED light source, or other collimated light sources. 
     According to additional features, the dial plaque can further comprise at least one telltale wherein the optical device redirects light from the light source at a location on the indicia and telltale to sequentially illuminate a location on the indicia and the telltale. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a front perspective view of an instrument cluster according to one example of the present teachings; 
         FIG. 2  is a front perspective view of an instrument cluster constructed in accordance to additional features of the present teachings; 
         FIG. 3  is a cross-sectional view of the instrument cluster of  FIG. 1 ; 
         FIG. 4  is an exemplary cross-sectional view of an instrument cluster according to another example of the present teachings and including a mirror having a reflector surface internal to its body and being coupled to a motor through a cannulated shaft; 
         FIG. 5  is a cross-sectional view of the mirror shown in  FIGS. 1 and 3 ; and 
         FIG. 6  is a cross-sectional view of the mirror shown in  FIG. 4 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     With initial reference to  FIG. 1 , an instrument cluster constructed in accordance with one example of the present teachings is shown and generally identified at reference numeral  10 . The instrument cluster  10  can include a fascia  12  having a display field  14 . The display field  14  can comprise a dial plaque  18 . The dial plaque  18  in one exemplary embodiment may be taken to be representative of a speedometer display with low values at the left end and higher values toward the right-most or clockwise end. In this way, the dial plaque can comprise a set of indicia  20  arranged generally around the dial plaque  18  to indicate a measured quantity (such as a vehicle speed). Those skilled in the art will readily appreciate that while the dial plaque  18  has been representative of a speedometer to indicate vehicle speed, the dial plaque  18  can be configured to represent indicia indicative of any measured quantity such as, but not limited to, engine speed (a tachometer), a coolant temperature, a fuel level, an oil pressure, a cabin temperature, and outside temperature, time (a clock) and the like. 
     It is appreciated that the cluster  10  can be arranged in any vehicle, such as an automobile, an aircraft, a boat, or for various parameters in a power plant. The indicia  20  can be in the form of increment or scale markers  22  that may be preprinted on the dial plaque  18  to give values to the measured quantities in miles per hour, kilometers per hour, degrees, rpm, psi, minutes, etc. The outline of the dial plaque  18  may also be printed, embossed or otherwise created on the fascia  12  of the cluster  10  for function and aesthetic appeal. 
     Various non-analog displays or “telltales” collectively referred to at reference numeral  24  can include a low fuel display  26 , turn signal arrows  30 ,  32 , engine temperature  34 , high beam light  36  and check engine  38 . Other telltales may also be provided. It will be noted that the telltales  24  can be physically arranged so as to correspond generally at an elevation on the dial plaque  18  consistent with the indicia  20 . 
     In another example shown in  FIG. 2 , a dial plaque  18 ′ can be divided into multiple display regions  18   a ,  18   b  and  18   c  for example. Each display region  18   a ,  18   b  and  18   c  can be configured to correspond to a different measured quantity (vehicle speed, engine speed and others identified above). In such a configuration, each display region  18   a ,  18   b  and  18   c  can have its own unique set of indicia  20   a ,  20   b  and  20   c.    
     According to one example, illumination markers are created in the display field  14  around a 360° sweep of the dial plaque  18  to identify a desired, measured quantity value on the dial plaque  18 , such as at the indicia  20  as well as concurrently illuminating any combination of the telltales  24  identified above. These illumination markers are created by a light source  40 , which operates in an on/off mode under the control of a high-speed controller  44 . In one example, the light source  40  can comprise a diode laser. The controller  44  can be configured to receive vehicle inputs  46  ( FIG. 3 ) from various vehicle components  48 . The controller  44  can include signal interpretation algorithms that interpret the vehicle inputs  46  and generate a set of light source signals as will be described. In one example, multiple transducers can be provided that are capable of sending electrical signals representing instantaneous values of the various measure quantities. The conversion of the electrical signals from analog to digital form may be carried out either within the controller  44  or externally thereof by a suitable A/D converter according to the preferences of the system. 
     The light source  40  according to a first example is configured to output an incident beam of light  50  in a direction toward an optical device  52  that is mounted for rotation about an axis  54 . The optical device  52  can be a simple curved surface mirror (like in this example embodiment) or other more complex optical components or systems that are capable to redirect and spread or focus the incident light. The optical device  52  can have a reflective surface  56  ( FIG. 3 ). The optical device  52  can be rotated by way of a shaft  58  that extends from a motor  62  at a high and continuous rate of speed so that the light reflected off the optical device  52  (hereinafter referred to as a secondary beam  66 ) sweeps angularly across the display field  14  from left to right in a clockwise fashion as explained in greater detail below. In the exemplary configuration of  FIG. 1 , the optical device  52  is located generally within a boundary of the dial plaque  18  and is operable to reflect light 360° around the dial plaque  18  to illuminate in any combination the indicia  20  and the telltales  24 . 
     The secondary beam  66  that is reflected off of the optical device  52  can also be reflected toward a photo-detector sensor  70 , the output of which is connected as an input  72  to the controller  44  for calibrating or “zeroing” purposes explained in detail below. In one example, a signal, hereinafter angular position signal  74  can be sent from the motor  62  to the controller  44  indicative of an angular position of the shaft  58  (and therefore the angular position of the optical device  52 ). In one example, the motor  62  can be a brushless DC motor. 
     With continued reference to  FIG. 1  and additional reference to  FIG. 3 , the relationship of the light source  40 , the optical device  52  and the motor  62  will be described in greater detail. In one example, the light source  40  can emit the incident beam  50  in a direction along the mirror axis  54 . With such a configuration, the optical device  52  is operable to reflect the incident light  50  as the secondary beam  66  around the dial plaque  18  in 360° of motion. 
     In operation, the light source  40  can be turned on to produce a calibration pulse, which is directed toward the photo-detector  70 . This resets the data in the controller  44  to the zero-sweep position, such that the pulses provided by the motor  62  can be representative of 0.1° of angular movement of the secondary beam  66  in the clockwise direction starting from the leftmost position of the display field  14  to be activated. In one example, this could equate to 3600 pulses per rotation of the optical device  52  or  1200  pulses for each horizontal beam sweep. Assuming 80% of the pulses are usable, 960 pulses are available to scale the display field  14  and  320  pulses are available for other areas of the dial plaque  18 , such as the telltales  24 . In theory, 960 pulses across a speedometer range of 150 miles per hour allows 0.156 miles per hour resolution between consecutive pulses. Assuming, by way of example, that the display field  14  represents vehicle speed and a value of 50 miles per hour near the one-third of the display field  14  is to be indicated, the vehicle inputs  46  are converted to a pulse count representing approximately one-third of the total pulse count required to displace the secondary beam  66  the full width of the display field  14 . When the angular position determined from the angular position signal  74  satisfies a predetermined value, the controller  44  outputs a signal, hereinafter light signal  80  that turns the light source  40  on and a stripe-like marker of light  82  ( FIG. 1 ) is caused to appear on the dial plaque  18  of the display field  14 . The light signal  80  can include light duration and starting point with regard to the angular position signal  74  of the motor shaft  58 . The controller  44  can also output a signal, hereinafter a shaft angular position control signal  84  to the motor  62 . The controller  44  can also have a light source driving function that compares the light signal  80  and the angular position signal  74 , determined by signal interpretation algorithms in the controller  44  and switch the light source  40  on/off per the comparison result. 
     Returning now to the example shown in  FIG. 2 , the controller  44  can output a signal (such as light signal  80  described above) such that the light source  40  comes on at strategic times to create secondary beams  66   a ,  66   b  and  66   c  for illumination markers  82   a ,  82   b  and  82   c  at each display region  18   a ,  18   b  and  18   c , respectively. 
     In one example, when the optical device  52  rotates sufficiently to direct the secondary beam  66  ( 66   a ,  66   b ,  66   c ,  FIG. 2 ) onto the indicia  20  ( 20   a ,  20   b ,  20   c ;  FIG. 2 ) of the dial plaque  18  ( 18 ;  FIG. 2 ), data from the vehicle inputs  46  can be converted to pulse counts to cause the light source  40  to come on at strategic times representing appropriate locations for illumination within the display field  14  to show the measured quantities (such as illuminate at an appropriate location on the indicia  20  ( 20   a ,  20   b ,  20   c ;  FIG. 2 ) and/or illuminate any of the telltales  24 ). In one example, the display field  14  is scanned repeatedly at a rate of approximately fifty times per second. In this way, each illumination marker, such as at  82  ( 82   a ,  82   b ,  82   c ;  FIG. 2 ) is “refreshed” about fifty times per second and the characteristics of human sight are such that flicker will not be detected. In one example, the mirror can be rotated at a constant speed such as, but not limited to 3600 RPM, 60 Hz. The human eye will tend to blend the optical stimuli to create the appearance of continuous illumination markers in the display field  14 . In one example, the telltales  24  may be physically defined by embossed outlines and more reflective or diffusive surface patterns to cause illumination blending. The light source  40  can be turned on continuously during the entire sweep across the telltales  32 ,  38 ,  36 ,  34 ,  26 , and  30  in sequence, whichever needs to be lit per the vehicle inputs  46 , so as to “paint” the entire surface of the telltales. 
     With additional reference now to  FIG. 5 , reflection of light on the optical device  52  according to the first example will be described. As shown, the incident beam  50  defines a width D and reflects off of the reflective surface  56  as the secondary beam  66 . In one example, the reflective surface  56  can be a portion of a cylinder. For different configurations, various mirrors can be provided having dissimilar shapes. 
     For bottom incident: 
                   R   =         {       D   2     ÷     cos   ⁡     [     180   -     (     90   -     α   2       )     -     θ   2       ]         }     ÷     sin   ⁡     (     α   2     )         ⁢           ⁢   or                 R   =       {       D   2     ÷     cos   ⁡     [     180   -     (     90   -     β   4       )     -     θ   2       ]         }     ÷     sin   ⁡     (     β   4     )                     For   ⁢           ⁢   top   ⁢           ⁢   incident                 R   =         {       D   2     ÷     cos   ⁡     [       (     90   -     α   2       )     -     θ   2       ]         }     ÷     sin   ⁡     (     α   2     )         ⁢           ⁢   or       ⁢                       R   =       {       D   2     ÷     cos   ⁡     [       (     90   -     β   2       )     -     θ   2       ]         }     ÷     sin   ⁡     (     β   2     )                     
Where:
         D: the incident beam width   α the active arc angle of the mirror reflect surface   β the desired spread angle of the secondary beam   θ the angle between the low edge of the secondary beam and the incident beam       

     With reference now to  FIGS. 4 and 6 , a cluster  110  according to additional features of the present disclosure will be described. The cluster  110  can be configured similar to the cluster  10  and have like components identified by reference numerals increased by 100. As a result, like components will not be repeatedly described with respect to the example of  FIGS. 4 and 6 . In the example provided in  FIGS. 4 and 6 , the light source  140  is arranged on an opposite side of the fascia  112  as the motor  162 . The motor shaft  158  is tubular and defines a cannulation  159  along its axis. The light source  140  is configured to emit incident light  150  through the cannulation  159  of the shaft  158  and onto a reflective surface  156  defined on the optical device  152 . The incident light  150  reflects off the reflective surface  156  of the optical device  152  as a secondary beam  166  and onto the display field  14 . As with the example described above with respect to  FIGS. 3 and 5 , the light source  140  is operable to emit the incident light  150  generally along the axis of rotation  154  of the optical device  152 . As with the first example, such a configuration can allow the optical device  152  to reflect a secondary beam  166  in a complete 360° sweep, thereby illuminating, in any combination, indicia and/or telltales provided on the display field  114 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.