Measuring instrument with an indicator

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.

The present invention relates to a measuring instrument, and more particularly, the present invention relates to a measuring instrument with an indicator.

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.

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.

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.

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.