AU4272578A - Illuminated indicator gauge - Google Patents

Description

COMMONWEL R W SIXTY L

Patents Act 19i. 106. 4c

CONVENTION-- APPLICATION FOR A PATEN 42725/7 1/We Nissan Motor Company, Limited, a company organized under the laws of Japan, of No. 2, Takara-cho, Kanagawa-ku, Yokohama City, Japan,

hereby apply for the grant of a Patent for an invention entitled

"Illuminated Indicator Gauge." *6

0

6o k which is described in the accompanying specification. complete

0 0

This application is made under the provisions of Part XVI of the Patents Act 1952-76and is based on an application for a patent or similar protection made

m' Japan on 28th February, 1978. S(53-25419) mx *0 0 *0

Dl./Our address for service is: F. B. Rice Co., 101 Mort St., Balmain, NSW 2041 00*

0

Dated this 19th day of December, 19 78. 0 0 Nissan Motor Cm any, Limit ted. 0 0

Patent Attorney

F. B. RICE CO., To: The Commissioner of Patents, Patent Attorneys, Commonwealth of Australia. Sydney.

i

DECLARATION IN SUPPORT OF ixy^xArSWISlK' A CONVENTION APPLICATION FOR A PATENT QW ~;~DX]AxxWx xAi

In support of the ovtio pictio Convention Application made 42 725/ 8 Nissan Motor Company, Limited

patent for a e for an invention entitled

"Illuminated Indicator Gauge." xIWe Ryoichi Nakagawa, Executive Managing Director of and care of the Applicant Company, do solemnly and sincerely declare as follows: x*0vtku Aikef a =m xQ("x1C=XW~~~xmM*As(C2Ppjis ;ib xy,)X0MbC ai~i6D~tx o a.. I am authorisedby Nissan Motor Company, Limited a. 0

patent 0 the applicant for the :tcref~bCD& patent XAdik to make this declaration

*I on its behalf. 3 0@ S 141 was 0 The basic application as defined by Section of the Act a *000 made in Japan on 28th February, 1978.

by the present Applicant Company.

0@ 0 Kenji NAKAMURA of No. 3-68, Oppama-higashicho, S@ Yokosuka City, Japan

S

0 Sr

is the actual inventor of the invention and the facts upon which Nissan Motor Company, Limited is/~ entitled to make the application are as follows:

The Applicant Company is the assignee of the invention from the said actual inventor.

The basic application referred to in paragraph 2 of this Declaration is/ g the first application made in a Convention country in respect of the invention the subject of the application.

Declared at Tokyo, Japan this 10th day of November 19 78 NISSAN MOTOR COMPANY, LIITED By: eivi Ryolfi NaKagawa, r. Executive Managing' rector F. B. RICE CO., To: The Commissioner of Patents Patent Attorneys, Commonwealth of Australia Sydney. This Form is suitable for any type of Patent Application. No legalisation required. I

(11) AU-A 1 42725/78

(12) PATENT SPECIFICATION ABSTRACT (19) AU

(21) 42725/78 (22) 20.12.78 (23) 20.12.78 (24) 28.2.78' (31) 53-25419 (32) 28.2.78 (33) JP (43) 6.9.79 (51) 2 G01D 13/04 G01D 13/26 G01P 1/08 (54) ILLUMINATED INDICATOR GAUGE (71) NISSAN MOTOR COMPANY, LTD. 72) NAKAMURA K. '74) RI (57) CLAIM

1. An illuminated indicator gauge comprising a

light-transmitting dial plate having a front face, a

light-transmitting pointer which is rotatable over the

front face of the dial plate about an axis substantially

normal to the front face and which has an inner end

portion containing said axis therein and an outer end

opposite to said inner end portion, and a light source

located in conjunction with said dial plate for emitting

rays uf light toward a perimetric portion of the dial

plate, wherein said dial plate has internally formed

therein a reflecting surface angled at 45 degrees to

said front face and said pointer has a reflecting surface

formed in said inner end portion thereof and angled at

degrees to said axis of rotation thereof and a matte

rear surface bevelled in its entirety toward said outer

(11) AU-Al 42725/78 2

end of the pointer, characterized by light condensing

means located between said light source and said re-

flecting surface in said dial plate for condensing the

light rays radiated from the light source toward the

reflecting surface in the dial plate.

33,2

COMMONWEALTH OF AUSTRALIA

Patents Act 1952- 1976.

C 0 Mv P L E T E SPEC 1F ICATI ON

(ORIGINAL)

42 Class Intb Class

pp Icrti on

,omplete iPpeclficrition Lodged Accepted: Published:

28th February, 1978. 0* 0

Nissan Motor ';ompany, Limited. same S of Applicant *0 S

S

S @5O ~ddress of Applicant No. 2, Takara-cho, Kanagawa-ku, SO Yokohama City, Japan. 0 Se 0

@55555

\.ctual Inventor Kenj i NAKAMURA

*0 S S of

Address for Service PICE CO,, Patent Attorneys, The Forth and Clyde, 10-1 Mort Street, BALMAIN. 2041. Complete Specification for the invention entitled:

"Illuminated Indicator Gauge."

The following statement is a full description of this invention including the best method of performing it 1inown to us

-1I-

The present invention relates to indicator gauges

Cq and, more particularly, to an illuminated indicator L__ C gauge to be installed on, for example, an instrument Spanel of an automotive vehicle.

A prior-art illuminated indicator gauge comprises

a transparent dial plate having an internal reflecting o, S surface which is arranged in such a manner that the rays 66

S) of light admitted into the dial plate from a light source

0: located in the vicinity of a perimetric portion of the S

dial plate are caused to change their directions of travel

toward a transparent pointer which is rotatable over the

front face of the dial plate in a usual manner. The rays

of light thus passed to the pointer from the reflecting S surface in the dial plate are further reflected at a

S reflecting surface formed on the pointer and the re- 66

directed toward a matte surface which is formed on an

outer end portion of the pointer. The beams of light 6* 6

S. 20 which are thus incident on the matte surface of the

pointer are diffusely reflected at the matte surface

and are scattered in various directions therefrom so

that the pointer is caused to light up in the region

of the matte surface thereof.

The light source utilized in an illuminated

la indicator gauge of the type thus arranged is usually r provided by a lamp of a miniature type which practically

Clconstitutes a point source of light. The rays of light

Cemanating from such a light source are radiated over a

considerable solid angle within the transparent dial

plate so that the beams of light admitted into the dial

plate are incident with different angles of incidence on the internal reflecting surface in the dial plate. It

therefore follows that the beams incident on the reflect- ing surface in the dial plate are reflected with different

angles of reflection toward the pointer so that not only

S-o o the rays of light originally admitted into the dial plate

are permitted to enter the pointer in a limited proportion

but the quantity of light to be incident on the reflecting.

surface of the pointer varies with the rotational position

of the pointer relative to the dial plate. These results

in a low luminaire efficacy available of the indicator gauge and further in inconstancy of the brightness to be

0, obtained of the pointer to be rotated over the dial plate. "0O The present invention contemplates elimination of these

problems encountered in prior-art illuminated indicator

gauges of the described type.

In accordance with the present invention, there is

provided an illuminated indicator gauge which comprises a light-transmitting dial plate having a front face, a light-transmitting pointer which is rotatable over ~1 the front face of the dial plate about an axis sub- c stantially normal to the front face of the dial plate and which has an inner end portion coniaining tte axis of rotation of the pointer therein and an outer end opposite to the outer end portion, and a light source located in conjunction with the dial plate for emitting rays of light toward a perimetric portion of the dial plate, wherein the dial plate has internally formed therein a reflecting surface which is angled at degrees to the front face of the dial plate and the o. pointer in turn has a reflecting surface formed in the inner end portion thereof and angled at 45 degrees to the axis of rotation of the pointer and a matte rear surface which is bevelled toward the outer end of the pointer, characterized by light condensing means located between the light source and the reflecting surface in the dial plate for condensing the light rays

28 radiated from the light source toward the reflecting

surface in the dial plate.

o The light condensing means of the indicator gauge

thus constructed and arranged preferably comprises a

light collimating element having a focus located in the

region of the light source or, when the light source v. constitutes a substantial point source of light, pre- Oa L ferably at the light source. Such a collimating element lmay be constituted by a convex lens located between the light source and the reflecting surface in the dial plate or may be integral with the dial plate. Each of the light-transmitting dial plate and pointer is con- structed of a transparent or translucent material.

The features and advantages of an illuminated

indicator gauge provided by the present invention will 4, be more clearly appreciated from the following description

taken in conjunction with the accompanying drawings in

55 S which like reference numerals designate corresponding or

*0 S o

S similar members and elements throughout the figures and

in which:

Fig. 1 is a cross-sectional view showing a repre-

sentative :xample of an illuminated indicator gauge of

the character to which the present invention appertains; S. Fig. 2A is a view similar to Fig. 1 but shows a

preferred embodiment of an illuminated indicator gauge

S according to the present invention; S. S Fig. 2B is a plan view showing the arrangement of 55

a light source and a dial plate forming part of the

indicator gauge illustrated in Fig. 2A;

Figs. 3, 4 and 5 are cross-sectional views showing other preferred embodiments of the illuminated indicator gauge according to the present invention;

Fig. 6A is a plan view showing the arrangement of

a light source and a dial plate forming part of still

'N another preferred embodiment of the illuminated indicator

C4 gauge according to the present invention; Fig. 6B is a cross-sectional view .of the arrangement

illustrated in Fig. 6A;

Fig. 7A is a view similar to Fig. 6A but shows the arrangement of a light source and a dial plate forming part of still another preferred embodiment of the illumi-

nated indicator gauge according to the present invention;

and

Fig. 7B is a cross-sectional view of the arrangement

illustrated in Fig. 7B.

Referring to Fig. 1 of the drawings, a known illumi-

S" nated indicator gauge 10 of the type to which the present

invention appertains comprises a generally circular dial

plate 12 having a front face provided with suitable scale garduations (not shown). The dial plate 72 has formed in

its center portion an axial hole 14 through which a shaft

16 having a center axis substantially normal to the front

face of the dial plate 12 axially projects from the front

face of the dial plate 12 and is rotatable about the center

5

i axis thereof with respect to the dial plate 12. The shaft 16 is securely connected at one end thereof to a pointer 18 having an inner end portion mounted on the

C leading end portion of the shaft 16 and an outer end

s portion opposite to the inner end portion and located

with an area coextensive with the front face of the dial

'd plate 12, The pointer 18 is thus rotatable over the

graduated front face of the dial plate 12 about an axis

aligned with the center axis of the shaft 16. Though not shown in the drawings, the shaft 16 is connected

at the other end thereof to a suitable drive mechanism

which is adapted to drive the pointer 18 to turn about

the axis of rotation thereof through an angle dictated

by a signal applied to the drive mechanism. Each of

the dial plate 12 and the pointer 18 thus arranged is

constructed of a suitable rigid, transparent or trans-

lucent material such as for example a transparent

g plastic. The dial plate 12 is fixedly held in place

within a suitable casing (not shown) forming part of

*200 the indicator gauge.

The dial plate 12 has further formed in the center ee.

i portion thereof an equilateral-prism-shaped recess

having a square-shaped open end at the rear end of the

dial plat. 12 and an oblique lateral plane inclined at

an angle of 45 degrees with respect to the front face of the dial plate 12. The oblique lateral plane thus defining an end of the recess 20 forms a bezel or inclined internal face constituting a flat reflecting

Ssurface 22 in the transparent or translucent dial plate

12. The recess 20 thus formed in the dial plate 12

Scontains therein a portion of the center axis of the

dial plate and is substantially aligned with the above-

mentioned inner end portion of the pointer 18 so that

the reflecting surface 22 in the dial plate 12 is

directed at 45 degrees toward the inner end portion of

the pointer 18.

On the other hand, the pointer 18 has formed on

the inner end portion thereof a bevelled external face

which is inclined at 45 degrees with respect to the

front face of the dial plate 12 and which constitutes

a flat reflecting surface 24 on the pointer 18. The

recess 20 in the dial plate 12 and the bevelled external

face of the pointer 18 are dimensioned so that the *o respective reflecting surfaces 22 and 24 of the dial

plate 12 and the pointer 12 are always substantially

aligned or largely coextensive with each other in a

direction parallel with the axis of rotation of the

pointer 18 without respect to the rotaticial position

of the pointer 18 over the dial plate 12. The outer

end portion of the pointer 18 has a matte rear surface

26 which is bevelled in its entirety toward the outer

end of the pointer.

A source of light as indicated at 28 is fixedly

located in conjunction with the dial plate 12 in such Ip a manner that the rays of light emanating from the light

source 28 are incident on the reflecting surface 22 in

t- the dial plate 12 through a perimetric portion 12a of

the dial plate 12 and form a beam of light A1 which

travels in a radial direction within the dial plate 12

S until the light beam A reaches the reflecting surface

S. 22. The beam of light A1 thus incident on the reflect-

ing surface 22 of the dial plate 12 is reflected at the

surface 22 and enters the transparent or translucent

pointer 18 in a direction substantially parallel with the axis of rotation of the pointer 18 as indicated at

A 2 in Fig. 1. The reflected beam of light A 2 advances

in the pointer 18 and is further reflected at the

reflecting surface 24 of the pointer 18 toward the

outer end portion of the pointer 18 as indicated at A 3

The light beam A 3 is incident on the bevelled matte S rear surface 26 of the outer end portion of the pointer g

18 and is diffusely reflected at the matte surface 26.

The light thus scattered in the outer end portion of

the pointer 18 illuminates the outer end portion of

the pointer 18 and enables the viewer of the indicator gauge 10 to visually recognize the scale graduation being indexed by the pointer 18. Indicated by phantom lines in Fig. 1 is a cover plate 30 which may be pro- vided to prevent leakage of light from the region surrounding the dial plate 12 into the viewer's visual field. Cq In the arrangement illustrated in Fig. 1, the flat C<l *qreflecting surface 22 formed in the dial plate 12

S" constitutes an oblique lateral surface of a

prism. If, therefore, collimated rays of light are 0e

incident on the reflecting surface 22 at 45 degrees to O

the reflecting surface, the light rays reflected from

the reflecting surface 22 of the dial plate 12 will be

permitted to be totally incident on the reflecting

surface 24 of the pointer 18. Since, however, the lamps

used as the sources of light in indicator gauges of the described character are usually of the miniature

type, the light source 28 provided in the indicator

gauge 10 virtually constitutes a point source producing

rays of light which are radiated over a considerable

solid angle within the dial plate 12. Thus, the light

rays emitted from the source 28 and entering the dial

plate 12 include beams of light B1 and C which are

incident upon the reflecting surface 22 of the dial

plate 12 at angles which are similar than 45 degrees as

9

nT in the case of th light beam B 1 or larger than degre as in the case of the light beam C 1 When the light beams incident on the reflecting surface 22 of

Sthe dial plate 12 at angles smaller or larger than

1Urdegrees are reflected from the reflecting surface 22,

some of the reflected light beams are not permitted

to enter the pointer 18 as in the case of the reflected

S light beam B 2 resulting from the initial light beam B 1 S* and some are enabled to enter the pointer 18 but are not

f permitted to proceed into the inner end portion of the

pointer 18 as in the case of the reflected light beam

C 2 resulting from the initial light beam C 1 Furthermore, 2 1 there will be such light beams that are permitted to be

incident upon the reflecting surface 24 of the pointer

but which are not reflected from the reflecting surface

24 toward the bevelled matte rear surface 26 of the

outer end portion of the pointer 18. Thus, only a

limited portion of the light originally emitted from

a* the light source 28 and admitted into the dial plate

12 is permitted to finally reach the bevelled matte

rear surface 26 of the pointer 18 after two reflections

in the dial plate 12 and the pointer 18. This results

in a low luminaire efficacy available of the indicator

gauge 10. Because, furthermore, of the fact that the

angles of incidence and accordingly the angles of reflection at the reflecting surface 22 in the dial plate 12 thus vary depending upon the locations at which the rays of light are incident on the reflecting surface 22, the quantity of the light which is permitted

Sto proceed from the reflecting surface 22 into the

C inner end portion of the pointer 18 varies with the

angular position of the pointer 18 with respect to the dial plate 12 so that the degree of brightness obtained eo

in the region of the outer end portion of the pointer 18 varies as the pointer 18 is rotated over the front S.

o• face of the dial plate 12 about the axis of rotation

~of the pointer. The present invention contemplates

resolution of these problems which have been inherent

in known illuminated indicator gauges of the type thus

far been described with reference to Fig. i. eso

Referring to Figs. 2A and 2B of the drawings, an illuminated indicator gauge embodying the present

invention as designated in its entirety by 10a is shown *ee

20 comprising, in addition to a transparent or translucent dial plate 12 and a transparent or translucent pointer

18 which are arranged similarly to their respective

counterparts in the prior-art indicator gauge 10 shown

in Fig. i, a thin, colored coating 32 applied to the

total area of the front face of the dial plate 12 and

a thin, opaque coating 34 applied to the outer surface of the colored coating 32 as illustrated in Fig. 2A.

The opaque coating 34 is transparent or void at 36 in

I the form of scale graduations and over its central area

36' substantially registering with the reflecting sur-

t" face 22 in the dial plate 12. The coatings 32 and 34

-zl may be applied to the diaJ. piate 12 by printing. The

dial plate 12 further has light reflective coatings 38

and 38' applied to the rear and outer peripheral sur-

:2 faces, respectively, of the diaj plate for aiding in

the illumination of tl'o scale graduations 36 in the

opaque coating 34 when the dial plate 12 is irradiated

with the light emanating from the light source 28.

In the embodiment illustrated in Figs. 2A and 2B,

there is provided a convex lens 40 located between the

light source 28 and the perimetric portion 12a of the

dial plate 12 in such a manner that the lens 40 h.-s one

of its foci at the light source 28 which is herein

o assumed to constitute a substantial point source as

previously noted. The light radiating out from the

light source 28 is thus collimated by the convex lens

and the beams of light issuing from the lens

enter the dial plate 12 through the above-mentioned

perimetric portion 12a of the dial plate in directions

substantially parallel with the front face of the dial

plate 12 as indicated by D 1 in Fig. 2A. All the beams

of light D 1 admitted into the dial plate 12 are inherent with the angles of about 45 degrees on the reflecting surface 22 in the dial plate 22 and are re-directed to advance away from the reflecting surface 22 in direc- tions substantially parallel with the axis of rotation t of the pointer 18 as indicated by D 2 in Fig. 2A. -he

,4 beams of light D 2 entering the inner end portion of the

pointer 18 are incident with the angles of 45 degrees

on the reflecting surface 24 of the pointer 18 and are

4 further re-directed toward the outer end portion of the

pointer 18 in directions substantially parallel with

a.. i the front face of the dial plate 12 as indicated by D 3

in Fig. 2A. The beams of light D 3 thus travelling in

the pointer 18 reach the matte rear surface 26 of the

pointer and are diffusely reflected at the surface 26

for being scattered in various directions in the pointer

18 and thereby lighting up the pointer 18 in the region a S of the matte rear surface 26 thereof. *i The convex lens 40 provided as light-condensing 4. means in the embodiment of Figs. 2A and 2B functions as S. 20 a collimating element effective to collimate the rays

of light radiated from the light source 28 and to

direct the collimated rays of light on to the reflect-

ing surface 22 in the dial plate 1. The rays of light

admitted into the dial plate 12 are therefore incident

with substantially equal angles on the reflecting surface 22 in the dial plate 12 so that the light rays re-directed after reflection at the reflecting surface tZ 22 are allowed to uniformly proceed into the inner end portion of the pointer 18 with substantially equal S" angles of incidence. For this reason, not only an

'f increased degree of brightness is obtained in the

region of the matte rear surface 26 of the pointer 18

but the degree of brightness remains substantially

constant when the pointer 18 is turned about the axis

of rotation thereof with respect to the dial plate 12.

The convex lens 40 provided in the embodiment of Figs.

:2A and 2B is assumed to be a bi-convex or convexo- convex lens by way of example but, if desired, may be replaced with a piano-convex or positive meniscus lens

(not shown). In the embodiment of Figs. 2A and 2B,

furthermore, the perimetric portion 12a of the dial

plate 12 is assumed to have a substantially flat end

face which is substantially perpendicular to the center

axis of the convex lens 40 as shown in Fig. 2B so that

20 the collimated rays of light issuing from the lens S. are precluded from being refracted at the end face of

the portion 12a when entering the dial plate 12.

.Fig. 3 shows an embodiment in which a collimating

element provided as light-condensing means between the

light source 28 and the reflecting surface 22 in the dial plate 12 is constituted by a convex lens formed as an integral portion of the transparent or translucent

E dial plate 12. The perimetric portion 12a of the dial

U1 plate 12 in the embodiment shown in Fig. 3 is formed

with a projection 42 having an outer face spherically

protruding toward the light source 28. The outer face

of the projection 42 thus formed of the perimetric

portion 12a of the dial plate 12 is arcuately curved

in cross-section with a radius of curvature which is

selected to provide a focus located at the light source

9 28 so that the rays of light radiated out from the

light source 28 are substantially collimated into beams 0e0

of substantially parallel light in the dial plate 12.

The collimated beams of light thus produced in the dial 9 9 4. plate 12 are incident with angles of 45 degrees on the

reflecting surface 22 in the dial plate 12 and provide

substantially the same effects as those achieved in **a

the embodiment of Figs. 2A and 2B.

While the collimating element provided in the 9

embodiment illustrated in Fig. 3 is located at a peri-

metric end of the dial plate 12, a collimating element 9S integral with the dial plate 12 may be formed internally 9 S of the dial plate and located between the perimetric

portion 12a and the reflecting surface 22 of the dial

plate. Figs. 4 and 5 show embodiments each incorporating such a collimating element.

In the embodiment illustrated in Fig. 4, the dial

plate 12 having the reflecting surface 22 is formed with

e U-: an opening 44 which is open at the front and rear ends

of the dial plate 12 and which is defined between a

substantially flat internal surface 44a located between

c^ the perimetric portion 12a and the reflecting surface

22 of the dial plate 12 and an internal projection 44b

located between the flat internal surface 44a and the

reflecting surface 22 in the dial plate 12 and spheri-

S: cally protruding away from the reflecting surface 22

toward the flat internal surface 44a and accordingly

toward the light source 28 across the internal surface

44a and the perimetric portion 12a of the dial plate 12. The flat internal surface 44a provided between the perimetric portion 12 and the internal projection 44b

of the dial plate 12 is assumed, by way of example,

S. to be substantially perpendicular to the center axis

of the internal projection 44b or to a line passing

o 20 through the light source 28 and the internal projection

44b in the dial plate 12.

The internal projection 44b thus formed in the

dial plate 12 has a surface which is arcuately curved in cross-section with a radius of curvature which is

selected to provide a focus located at the light source

28. The rays of light emanating from the light source

28 and admitted into the dial plate 12 through the

perimetric portion 12a of the dial plate 12 travel with V- C a certain solid angle within the dial plate 12 as

Sindicated by E 1 until the beams of light E 1 reach the

internal projection 44b in the dial plate 12. The beams of light E 1 are collimated at the spherically

protruding surface of the internal projection 44b in

the dial plate 12 and the resultant beams of parallel

light, indicated by E 2 are incident on the reflecting

surface 22 in the dial plate 12 with the angles of

incidence of about 45 degrees.

The collimating element provided in the embodiment

of Fig. 5 is essentially similar in effect to the Scollimating element constituted by the internal pro-

jection 44b in the embodiment of Fig. 4 and is formed

in the dial plate 12 having an opening 46 which is open

at the front and rear ends of the dial plate 12. The

opening 46 is defined between a substantially flat

20 internal surface 46a located between the perimetric portion 12a and the reflecting surface 22 of the dial C

plate 12 and an internal projection 46b located between the flat internal surface 46a and the perimetric portion 12a of the dial plate 12 and spherically protruding away

from the perimetric portion 12a toward the flat internal surface 46a and accordingly toward the reflecting surface 22 in the dial plate 12 across the flat internal

Ssurface 46a. The flat internal surface 46a provided

between the internal projection 46b and the reflecting

t- surface 22 of the dial plate 12 is assumed, by way of

example, to be substantially perpendicular to the center

axis of the internal projection 46b or to a line passing

through the light source 28 and the internal projection

46b in the dial plate 12. The internal projection 46b

thus formed in the dial plate 12 has a surface which is

arcuately curved in cross-section with a radius of

curvature which is selected to provide a focus located S

at the light source 28. The rays of light radiated out

from the light source 28 and admitted into the dial S. o 0 plate 12 through the perimetric portion 12a of the dial plate 12 travel with a certain solid angle within the

dial pl.ate 12 as indicated by F 1 until the beams of

light F 1 reach the spherically protruding surface of

the internal projection 46b in the dial plate 12. The

20 beams of light issuing from the internal projection 46b S. are collimated into beams of substantially parallel

light F 2 which are incident with the angles of about 45 degrees on the reflecting surface 22 in the dial

plate 12.

In each of the embodiments illustrated in Figs. 4 and 5, the perimetric portion 12a of the dial plate 12 is assumed to have a substantially flat end face which is substantially perpendicular to the center axis of the internal projection 44b or 46b in the dial plate 12

C or to a line passing through the internal projection 44b

or 46b and the light source 28 which is assumed to

practically constitute a point source of light.

If the perimetric portion 12a of the dial plate 12

has it3 end face arcuately curved about an axis which is

coincident or otherwise substantially parallel with the

center axis of the dial plate 12 as shown in Fig. 6A, the particular portion 12a of the dial plate 12 is go

operable per se as light condensing mearn without having

recourse to the provision of any additional collimating S. element between the light source 28 and the reflecting

surface 22 in the dial plate 12. If, in this instance,

the radius of curvature of the arcuately curved end

face of the perimetric portion 12a of the dial plate 12 is selected so that the perimetric portion 12a consti-

20 tutes a cylindrical convex lens having a focal axis located at the light source 28, the rays of light

proceeding from the light source 28 into the dial plate

12 through the perimetric portion 12a are substantially

I collimated in planes parallel with the front face of

the dial plate 12 or perpendicular to the axis of curvature of the perimetric portion 12a as indicated by G in Fig. 6A, although the beams of light admitted into the dial plate 12 are left to radiate within the

L dial plate in planes normal to the front face of the

dial plate 12 as indicated by G' in Fig. 6B until the

t" beams of light G' are incident on the reflecting surface

md 22 in the dial plate 12.

Figs. 7A and 7B show an embodiment in which the

perimetric portion 12a of the dial plate 12 is configured

in such a manner as to constitute a cylindrical convex

lens which is integral with the dial plate 12 ap in the

S. arrangement illustrated in Figs. 6A and 6B but which has

an axis substantially parallel with the front face of the dial plate 12. Thus, the perimetric portion 12a of 9e the dial plate 12 in the embodiment of Figs. 7A and 7B

has an end face which is elongated a suitable length

substantially perpendicularly to a line passing through

the light source 28 and the reflecting surface 22 or

more exactly the center axis of the dial plate and

which arcuately protrudes in cross-section toward the

light source 28 with a radius of curvature which is S such that the cylindrical convex lens constituted by

the perimetric portion 12a of the dial plate 12 has a

focal axis which passes through the light source 28.

The rays of light proceeding from the light source 28 into the dial plate 12 through the perimetric portion

12a of the dial plate are therefore left to radiate

within the dial plate 12 in planes parallel with the

VJ3 front face of the dial plate 12 as indicated by H in CV Fig. 7B but are substantially collimated in planes

normal to the front face of the dial plate 12 as

indicated by H' in Fig. 7A.

It has been assumed that the light source 28 in

each of the embodiments hereinbefore described is

positioned fixedly with respect to the dial plate 12

*s

b* element or the lens portion of the dial plate 12 is

determined depending upon the position of the light

source 28 relative to the dial plate 12 but the focal e Se point or axis of the collimating element or the lens

portion provided in each embodiment may be determined

arbitrarily if there is an allowance for selecting

the position of the light source 28 with respect to the

;o dial plate 12 which is assumed to be held stationary.

o20 While, furthermore, it has also been assumed that the focal point or axis of the collimating element or the

lens portion of the dial plate 12 in each of the

embodiments described is located at the light source

28 which is assumed to practically constitute a point

source of light or, conversely, that the light source

28 as the point source is located at the focal point

or axis, such an arrangement is not of critical tr. importance in carrying out the present invention and,

r thus, the focal point or axis of the collimating

Selement or the lens portion of the dial plate 12 in

each of the embodiments described may be located

slightly off the light source 28 or, conversely, the

light source 28 may be located slightly off the focal

o point or axis of the collimating element or the lens

portion of the dial plate 12. Where the collimating

element is constituted by the lens portion of the dial

plate 12 as in each of the embodiments described with

oo• reference to Figs. 3 to 7B, the collimating element

need not be configured in such a manner as to have a

focal point or axis at a definite point or axis insofar as the radiant beams of light incident on the colli-

mating element can be concentrated or condensed to a

satisfactory extent after the beams of light are passed

through the collimating element.

Although, furthermore, it has been assumed that

go the dial plate 12 has a center axis and that the axis of

rotation of the pointer 18 rotatable over the front face

of the dial plate 12 is substantially in aline with the

center axis of the dial plate 12 as in an ordinary

speedometer installed on the instrument panel of an automotive vehicle, the present invention is applicable to an indicator gauge of the type in which the dial plate has no definite center axis therethrough or in u~which the dial plate has a definite center axis there- through but the axis of rotation of the pointer rotatable

Swith respect to the dial plate is offset from the center

axis of the dial plate as in a voltmeter, an oil gauge,

a fuel gauge or a temperature gauge for, for example, automotive use.

*ee

S SC

0*

Claims (1)

1. THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

   i. An illuminated indicator gauge comprising a

   light-transmitting dial plate having a front face, a

   light-transmitting pointer which is rotatable over the

   front face of the dial plate about an axis substantially coi normal to the front face and which has an inner end

   portion containing said axis therein and an outer end G-1* U1_ opposite to said inner end portion, and a light source c 'A located in conjunction with said dial plate for emitting rL-

   0:O rays of light toward a perimetric portion of the dial

   plate, wherein said dial plate has internally formed

   therein a reflecting surface angled at 45 degrees to

   said front face and said pointer has a reflecting surface

   formed in said inner end portion thereof and angled at

   degrees to said axis of rotation thereof and a matte

   rear surface bevelled in its entirety toward said outer

   end of the pointer, characterized by light condensing

   means located between said light source and said re- **494 .00 0* 0 ,lecting surface in said dial plate for condensing the

   light rays radiated from the light source toward the

   reflecting surface in the dial plate.

   2. An illuminated indicator gauge as set forth in

   Claim i, in which said light condensing means comprises

   a light collimating element having a focus located in

   the region of said light source.

   3. An illuminated indicator gauge as set forth in

   Claim 2, in which said light source constitutes a sub-

   stantiil point source of light and in which said focus is tz located at said light source.

   4. An illuminated indicator gauge as set forth in

   Claim 2 or 3, in which said collimating element consists

   of a convex lens located between said light source and

   said perimetric portion of the dial plate.

   An illuminated indicator gauge as set forth in S

   .4 SE Claim 2 or 3, in which said collimating element is V D integral with said dial plate.

   6. An illuminated indicator gauge as set forth in

   Claim 5, in which said collimating element is constituted rE,,

   by said perimetric portion of said dial plate.

   7. An illuminated indicator gauge as set forth in

   Claim 6, in which said perimetric portion of said dial

   plate has a projection substantially spherically pro-

   S truding away from said reflecting surface in the dial

   plate and toward said light source.

   8. An illuminated indicator gauge as set forth in

   Claim 6, in which said perimetric portion has an outer

   face which is arcuately curved about an axis substantially

   parallel with the axis of rotation of said pointer.

   9. An illuminated indicator gauge as set froth in

   Claim 6, in which said perimetric portion has an outer

   25

   I, face which is arcuately curved about an axis substan- tially parallel with said front race of said dial plate. co An illuminated indicator gauge as set forth in

   Claim 5, in which said dial plate is formed with an

   opening defined between a substantially flat internal

   4 surface located between said perimetric portion and

   said reflecting surface in the dial plate and an inter-

   nal projection substantially spherically protruding

   toward said internal surface, said collimating element

   being constituted by said internal projection.

   11. An illuminated indicator gauge as set forth in

   Claim 10, in which said internal projection is located

   between said internal surface and said reflecting surface

   in said dial plate and protruding toward said perimetric

   portion of the dial plate.

   12. An illuminated indicator gauge as set forth in

   C3aim 10, in which said internal projection is located

   between said internal surface and said perimetric

   S portion of the dial plate and protruding away from

   said perimetric portion.

   13. An illuminated indicator gauge constructed and

   arranged substantially as described herein with refer-

   ence to the accompanying drawings.

   DATED this 18th day of December, 1978. Nissan Motor Company, Limited, Patent Attorneys for the Applicant, F.B. RICE CO.