Abstract:
A display is provided having five light-emitting elements, constituting a first light source, are provided on the surface of a wiring board. These sources illuminate a graduated board and a light-emitting indicator. A single light-emitting element, constituting a second light source, is provided on the surface of the wiring board as an illumination light source for use on the graduated board so as to oppose a concave portion of the light-guiding plate via the opening portion of the holder on an outside of one of the respective light-emitting elements.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present invention is related to Japanese patent application No. Hei. 11-247698, filed Sep. 1, 1999; the contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a measuring instrument, and more particularly, the present invention relates to a measuring instrument with an indicator. 
     BACKGROUND OF THE INVENTION 
     Conventionally, for example, measuring instrument indicators are used, such as for an automobile, such as the one illustrated in JP-A-9-21655. Here, a light-emitting indicator is supported at its rotating base by a forward end of an indicator shaft that passes through a through-hole of a graduated board and a light-guiding plate. These items are concurrently disposed on a reverse surface of this graduated board and extend from a rotating machine. Also, a plurality of light-emitting elements, constituting a light source, are disposed around the indicator shaft at positions corresponding to the rotating base of the light-emitting indicator on a reverse surface side of the light-guiding plate. These light-emitting elements provide light into the light-emitting indicator through the respective through-hole of the light-guiding plate and graduated board, from the rotating base portion thereof. At the same time, light enters the light-guiding plate from the through-hole from this same source. 
     However, in the above-described device, light from each respective light-emitting element is incident upon both the light-emitting indicator and the light-guiding plate. As such, even though light incident upon the light-emitting indicator is sufficient, light incident upon the graduated board from the light-guiding plate through the reverse surface is insufficient. As a result, the graduated board has reduced brightness. The present invention was developed in light of these drawbacks. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes these and other drawbacks by providing a measuring instrument with an indicator having light-transmitting graduated boards, a light-guiding plate provided along a reverse surface of the graduated board, a rotating inside machine provided on a reverse-surface side of the light-guiding plate and having an indicator shaft passing through a through-hole of the light-guiding plate and a through-hole of the graduated board. The measuring instrument further has light-emitting indicators supported at a forward end portion of the indicator shaft by a rotating base portion so as to rotate along a surface of the graduated board. A first light source is disposed on a reverse-surface side of the light-guiding plate around the indicator shaft which causes the light to enter the light-emitting indicator from the rotating base portion through the respective through-hole portions and causes the light to enter the graduated board through the light-guiding plate. 
     a second light source is disposed at a position spaced from the indicator shaft from the first light source in the radial direction and arranged to cause the light to enter the graduated board through the light-guiding plate. 
     As a result, the first light source illuminates the light-emitting indicator and the graduated board. The second light source illuminates only the graduated board  20   a.  Accordingly, even when light from the first light source on the graduated board is insufficient compared to light from the first light source on the light-emitting indicator, the second light source compensates for this insufficiency. As a result, the graduated board as well as the light-emitting indicator are properly illuminated. 
     In another aspect of the present invention, a black face is provided on the graduated board via an annular end plate to oppose the surface of the graduated board and light-emitting element. 
     In another aspect of the invention, a first light source is a plurality of light-emitting elements disposed around the indicator shaft at substantially equal distances from the indicator shaft in the radial direction. A second light source is provided which is a single light-emitting element. 
     In a further aspect of the invention, the measuring instrument has a wiring board provided along a reverse surface of the light-guiding plate. The first light source is a plurality of light-emitting elements provided on the wiring board and electrically connected to this wiring board and the second light source is. a single light-emitting element provided on said wiring board and electrically connected to this wiring board, and the rotating inside machine is electrically connected to the wiring board. 
     In another aspect of the invention, the light-guiding plate is equipped, on an opposite surface, with a concavity portion opposing the light-emitting element constituting the second light source. The second light source causes the light to enter the concavity portion before the light enters the graduated board through the light-guiding plate. 
     In another aspect of the invention, the first light source is a plurality of light-emitting diodes radially disposed around the indicator shaft at substantially equal distances from the indicator shaft. The second light source is a light-emitting diode. 
     In another aspect of the invention, a wiring board is provided along a reverse surface of the light-guiding plate, and the respective light-emitting elements are light-emitting diodes provided on the wiring board and electrically connected to the wiring board along with the rotating inside machine. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a front view of a measuring instrument with an indicator according to the present invention; 
     FIG. 2 is a sectional view taken along the line  2 — 2  of FIG. 1 of a measuring instrument with an indicator according to the present invention; and, 
     FIG. 3 is a sectional view taken along the line  3 — 3  of FIG. 1 of a measuring instrument with an indicator according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIGS. 1 to  3 , the present invention is shown in conjunction with a vehicle combination meter. This combination meter is disposed on an instrument panel within a vehicle compartment of a relevant automobile, and this combination meter, as illustrated in FIGS. 1 to  3 , is equipped with a instrument board  10 , and a tachometer  20 , an indicator  30 , and a speed meter  40  each of which is disposed on the instrument board  10 . 
     In FIG. 1, the tachometer  20  is equipped with a graduated board  20   a  formed on the instrument board  10 . A rotating machine  20   b  is provided on the reverse surface side of the instrument board  10 , at a position corresponding to the graduated board  20   a.  For direction purposes, a reverse surface is a position opposite the visual display side of the display. The graduated board  20   a  is provided on the illustrated right side portion in FIG. 1 of the instrument board  10 . Other than the graduated board  20   a  and an indicator portion  30   a,  the graduated board  40   a  is preferably colored black. 
     The graduated board  20   a  is equipped with a substantially circular-arc like graduated portion  21  that indicates the engine RPM. Moreover, the graduates and numerals of graduated portion  21  are colored black. Also, graduated board  20   a  is arranged to transmit light except for the graduates and numerals of graduated portion  21 . 
     Rotating machine  20   b  has a drive portion  22 , and an indicator shaft  23 . The indicator shaft  23  rotatably extends upward from the drive portion  22 , passing through through-hole portion  71  of circuit board  70 , an opening portion  61  of a holder  60 , a cylindrical. portion  51  of a light-guiding portion  50 , and a through-hole portion  11  of the instrument board  10  (that also serves concurrently as a through-hole portion of the graduated board  20   a ). However, the rotating machine  20   b  is supported within a casing  80 . It is to be noted that the drive portion  22  causes the indicator shaft  23  to rotate according to the electromagnetic force corresponding to the input. Also, the casing  80  is coaxially assembled to an annular end plate  90  via the circuit board  70 , holder  60 , light-guiding plate  50 , and instrument board  10 . 
     Also, the tachometer  20  is equipped with a light-emitting indicator  20   c  having an indicator main body  24  and a cover  25 . The indicator main body  24  is longitudinally formed of transparent light-guiding resin material and supported by a forward end portion of the indicator shaft  23  via a boss of its rotating base portion  24   a.  As illustrated in FIG. 2, rotating base portion  24   a  is equipped with an inclined surface  24   b  which reflects light. 
     Cover  25  covers the indicator main body  24  and has a slit  25   a  on an upper wall corresponding to an upper surface of an indicator portion  24   c.  As such, in indicator  20   c,  when light enters rotating base portion  24   a  from a reverse surface thereof, this light is reflected by the inclined surface  24   b  into the indicator portion  24   c.  The light within the indicator portion  24   c  then exits through slit  25   a  of the cover  25 . Thus, indicator portion  24   c  is illuminated from the slit  25   a.  Balancer  26  is also shown in FIG.  2 . 
     Light-guiding plate  50  is disposed on the instrument board  10  along a reverse surface thereof and is integrally equipped with the above-described cylindrical portion  51 . Cylindrical portion  51  is located beneath through-hole portion  11  of the graduated board  20   a  and coaxially with the indicator shaft  23  to permit the indicator shaft  23  to be inserted therethrough: Cylindrical portion  51  faces, with its upper end surface  51   a,  the opposite surface of rotating base portion  24   a  of the light-emitting indicator  20   c  through through-hole portion  11  and the opening portion  25   b  of the cover  25 . Cylindrical portion  51  reflects light, entering its lower portion  51   b  from around the cylindrical portion  51 , upward with reflecting surface  51   c.  Reflecting surface  51   c  has a tapered section which is incident from the upper end surface  51   a  upon the rotating base portion  24   a  of the indicator main body  24 . Here, reflecting surface  51   c,  as illustrated in FIG.  2  and FIG. 3, is formed to go along the inner-peripheral surface of the lower portion  51   b  of the cylindrical portion  51  and upwardly converge. 
     Also, the light-guiding plate  50 , at its cylindrical portion  51 , is formed with a lower holder portion  60   b,  into a converging shape as shown in FIG.  2 . As a result of this, light incident from around the cylindrical portion  51  upon the interior of the light-guiding plate  50 , is incident upon the interior of the lower portion  51   b.  as well as an outer-peripheral side portion of the cylindrical portion  51  other than the cylindrical portion  51 . The light-guiding plate  50  is formed of light guiding resin material. 
     The holder  60 , as illustrated in FIG. 2, is equipped with an annular frame  60   a  and a holder portion  60   b  formed at an end of annular frame  60   a.  The holder portion  60   b  accommodates therein the light-guiding plate  50 , and also plays the role of reflecting the light within this light-guiding plate  50  toward the interior of the light-guiding plate. 
     Wiring board  70  is clamped between casing  80  and holder  60 , and is located along the drive portion  22  and in parallel with the instrument board  10 . In this embodiment, the wiring board  70  is constructed of a printed board. 
     Five light-emitting elements  72  constituting a first light source are provided on a surface of the wiring board  70  at intervals spaced from each other. As a result, they face around cylindrical portion  51  of the light-guiding plate  50  through the opening portion  61  of the holder  60   b.  Light-emitting elements  72  cause light to enter from below and toward the cylindrical portion  51  of the light-guiding plate  50  and the surrounding area through the opening portion  61  of the holder portion  60   b.  As a result, light from the respective light-emitting elements  72  enter cylindrical portion  51  of the light-guiding plate  50  and its outer-peripheral side portion. The respective light-emitting elements  72  are located at positions spaced at approximately equal distances from the indicator shaft  23  in the radial direction. 
     Also, a light-emitting element  73 , constituting a second light source, is provided on the surface of the wiring board  70 , opposite a concavity portion  52 . There is an opening portion  61  of the holder portion  60   b.  Light-emitting element  73  provides light into a portion of the light-guiding plate  50 , other than through the cylindrical portion  51 . Here, concavity  52  has a V shape section proximate the reverse surface of the light-guiding plate  50 . Concavity  52  is situated on an inner-peripheral side of the opening  61  of the holder  60   b.  However, the configuration of concavity  52  is not limited to a V-shape, but may be any shape which introduces light from light-emitting element  73  into the light-guiding plate  50 . In this embodiment, each of the respective light-emitting elements  72  and  73  is constructed of a light-emitting diode. 
     Speed meter  40  is constructed in substantially the same way as the tachometer  20 . Accordingly, vehicle speed meter  40  has a graduated board  40   a  formed on the instrument board  10 , a rotating machine disposed on a reverse surface side of the instrument board  10 , and a light-emitting indicator  40   c  supported by a forward end portion of an indicator shaft. The indicator shaft extends from the rotating machine in substantially the same way as in indicator shaft  23 . The graduated board  40   a  is equipped with a display pattern portion  41  for displaying the vehicle speed of an automobile. 
     The indicator  30  is equipped with an indicator portion  30   a  formed on the instrument board  10 . A front panel  100  having a black face is also provided. Also, in this embodiment, the respective light-emitting elements  72 ,  73  and rotating machine  20   b  and the rotating inside machine  20   b  of the speed meter  40  are electrically connected to the wiring of the wiring board  70 . It is to be noted that the front panel  100  is formed of smoke material having a transmittance of approximately 20%. 
     In this embodiment, using tachometer  20  for example, each of the light-emitting elements  72  transmits light into indicator main body  24 . This light travels to rotating base portion  24   a,  through the cylindrical portion  71  of the light-guiding plate  50  and. through-hole  11 . Light also enters the graduated board  20   a  through the portion other than the cylindrical portion  51  of the light-guiding plate  50 . As such, each of the respective light-emitting elements  72  that constitute the first light source illuminates both for the light-emitting indicator  20   c  and the graduated board  20   a.    
     As a result, even when insufficient light from the respective light-emitting elements  72 , compared to light from light-emitting elements  72  entering light-emitting indicator  20   c,  enters the graduated board  20   a,  the light-emitting element  73  compensates for the illumination insufficiency of graduated board  20   a.  Accordingly, graduated board  20   a  and indicator  20   c  are properly illuminated even with the black face of front panel  100 . 
     It is to be noted that the wiring board  70  is not limited to the printed board and may be of any type of circuit board enabling the wiring and connection in general. Also, the present invention is not limited to a combination meter but may be applied to a measuring instrument with a speed meter only or an instrument with a tachometer only. Moreover, the light-emitting elements are not limited to light-emitting diodes, and may be, for example, light-emitting elements such as lamps, coldcathode tubes, or electro-luminescence element. Also, the number of light-emitting elements  72  or  73  is not limited to five, and may be changed. Also the number of concave areas  52  may also be changed corresponding to the number of the light-emitting elements  73 . 
     Also, even when forming a through-hole in the light-guiding plate  50  in place of the cylindrical portion  51 , an inner-peripheral surface may be formed such that it downwardly converges. This causes the light of each light-emitting element  72  to directly enter the rotating base portion  24   a  through the through-hole portion and causes the light incident upon the light-guiding plate  50  at around this through-hole portion from each light-emitting element  72  to be reflected by said inner-peripheral surface into the light-guiding plate  50 . It is possible to achieve substantially the same function and effect as those attainable with the above-described embodiment. Lastly, the present invention is not limited to automobiles, but may be applied to measuring instruments having indicators for use. on various kinds of vehicles. Also the invention may be applied to measuring instruments with indicators for use on general industrial machinery and tools. 
     While the above-described embodiments refer to examples of usage of the present invention, it is understood that the present invention may be applied to other usage, modifications and variations of the same, and is not limited to the disclosure provided herein.