Indicating instrument

[0002] The present application is based on and claims priority from Japanese Patent Applications Hei 6-277648 filed on Nov. 11, 1994 and Hei 7-183674 filed on Jul. 20, 1995, the contents of which are incorporated herein by reference.

[0003] 1. Field of the Invention

[0004] The present invention relates to an indicating instrument for use in various devices or machines and particularly in an automobile.

[0005] 2. Description of Related Art

[0006] In a conventional gauge installed in an automobile, generally an arc-shaped lighting tube is disposed behind a trans-illuminous dial plate along the indicating portion to illuminate the front surface thereof as shown in Japanese Unexamined Patent Publication Hei 2-80916.

[0007] Since the lighting tube is disposed along the indicating portion, the thickness of the above gauge can be made thin.

[0008] However, if a plurality of such gauges are installed in a car, the combined instrument structure becomes rather complicated and requires many parts, resulting in a cost increase in manufacturing.

[0009] In addition, different arc-shaped-lighting-tubes have to be provided for gauges having different-shaped dial plates.

[0010] Japanese Unexamined Patent Publication Hei 3-183912 discloses a dial gauge which has a partial-cylindrical reflector secured through a light diffusing plate to the back of the dial plate and a straight lighting tube disposed in the reflector. A driving shaft for a dial indicator extends from the back of the reflector through the reflector, the diffusing plate and the dial plate to the front of the dial plate.

[0011] However, the driving shaft for the dial indicator of the above described gauge is extremely long and the gauge becomes considerably thick. The extremely long shaft may increase the response time of the indicator and the hysteresis of the indication, thereby decreasing indication accuracy.

[0012] The present invention is made in view of the foregoing problems, and has a primary object of providing a thin and highly responsive indicating instrument having a straight illumination lamp and a light conducting plate.

[0013] Another object of the present invention is to provide an indicating instrument which includes a dial plate having a patterned trans-illuminous portion, a straight illumination lamp disposed behind the dial plate near the patterned portion, a light conducting plate disposed behind the dial plate in an optical path between the illumination lamp and the patterned trans-illuminous portion, whereby the patterned trans-illuminous portion is illuminated by the straight illumination lamp evenly using a simple structure.

[0014] Another object of the present invention is to provide a simple and thin indicating instrument which includes a straight illumination lamp, a plurality of patterned trans-illuminous portions, a light conducting plate having through holes respectively corresponding to through-holes in the patterned trans-illuminous portions, a plurality of driving units having driving shafts respectively corresponding to the patterned portions, and a plurality of luminous indicators connected respectively to the shafts through the respective through holes of the light conducting plate, whereby the patterned trans-illuminous portions and the luminous indicators are illuminated by a single straight illumination lamp evenly.

[0015] Other objects, features and characteristics of the present invention as well as the functions of related parts of the present invention will become clear from a study of the following detailed description, the appended claims and the drawings. In the drawings:

[0016] FIG. 1 is a cross-sectional side view illustrating a main portion of an indicating instrument according to a first embodiment of the present invention;

[0017] FIG. 2 is a front view illustrating the first embodiment;

[0018] FIG. 3 is an exploded view illustrating main portions of a dial plate, a light diffusing plate and a holder of the first embodiment shown in FIG. 1;

[0019] FIG. 4 is a front view illustrating a first variation of the first embodiment;

[0020] FIG. 5 is a front view illustrating a second variation of the first embodiment;

[0021] FIG. 6 is a front view illustrating a partial variation of the firs variation;

[0022] FIG. 7 is a front view illustrating a third variation of the first embodiment;

[0023] FIG. 8 is a cross-sectional view cut along a line indicated by 8—8 in FIG. 7;

[0024] FIG. 9 is a front view illustrating a fourth variation of the first embodiment;

[0025] FIG. 10 is a cross-sectional view cut along a line indicated by 10—10 in FIG. 9;

[0026] FIG. 11A and FIG. 11B are cross-sectional side views illustrating other partial variations of the fourth variation;

[0027] FIG. 12A, FIG. 12B and FIG. 12C are cross-sectional side views illustrating other partial variations of the fourth variation;

[0028] FIG. 13 is an exploded view illustrating main portions of another partial variation of the fourth variation;

[0029] FIG. 14 is a front view illustrating a main portion of a fifth variation of the first embodiment;

[0030] FIG. 15 is an exploded view illustrating main portions of a dial plate, a light conducting and a holder of the first embodiment shown in FIG. 14;

[0031] FIG. 16 is a front view illustrating a main portion of a variation of the fifth variation;

[0032] FIG. 17 is an exploded view illustrating main portions of a dial plate, a light conducting plate and a holder of the first embodiment shown in FIG. 16;

[0033] FIG. 18 is a front view illustrating a sixth variation of the first embodiment;

[0034] FIG. 19 is a front view illustrating a seventh variation of the first embodiment;

[0035] FIG. 20 is a cross-sectional side view illustrating a main portion of an indicating instrument according to a second embodiment of the present invention;

[0036] FIG. 21 is an exploded view illustrating a light source unit;

[0037] FIG. 22 is a schematic view illustrating optical paths of the light source unit;

[0038] FIG. 23 is a schematic view illustrating a partial variation of the light source unit illustrated in FIG. 20;

[0039] FIG. 24 is a cross-sectional side view illustrating a main portion of an indicating instrument according to a third embodiment of the present invention;

[0040] FIG. 25 is an explanatory view illustrating an optical path of a luminous indicator points toward a cold-cathode-fluorescent lump in the indicating instrument according to the third embodiment;

[0041] FIG. 26 is an explanatory view illustrating an optical path of a luminous indicator points toward opposite the cold-cathode-fluorescent lump in the indicating instrument according to the third embodiment;

[0042] FIG. 27A is a cross-sectional view illustrating a main portion of a variation of the third embodiment cut along a line 27—27 shown in FIG. 27B, and

[0043] FIG. 27B is a front view thereof.

[0044] FIG. 28 is a schematic views illustrating other partial variations of the third embodiment;

[0045] FIG. 29 is a cross-sectional side view illustrating a main portion of an indicating instrument according to a fourth embodiment of the present invention;

[0046] FIG. 30 is a plan view illustrating a luminous indicator illustrated in FIG. 29;

[0047] FIG. 31 is a cross-sectional view illustrating a main portion of a variation of the fourth embodiment;

[0048] FIG. 32 is a cross-sectional side view of a main part illustrating a variation of the indicator illustrated in FIG. 31;

[0049] FIG. 33 is a cross-sectional side view of a main part illustrating a variation of the indicator illustrated in FIG. 32;

[0050] FIG. 34 is a cross-sectional side view of a main part illustrating another variation of the indicator illustrated in FIG. 32;

[0051] FIG. 35 is a plan view illustrating another variation of the fourth embodiment;

[0052] FIG. 36 is a cross-sectional side view cut along a line 36—36 in FIG. 35;

[0053] FIG. 37 is a cross-sectional side view cut along a line 37—37 in FIG. 35;

[0054] FIG. 38 is a cross-sectional side view cut along a line 38—38 in FIG. 35;

[0055] FIG. 39 is a plan view illustrating a variation of the luminous indicator illustrated in FIG. 29;

[0056] FIG. 40 is a plan view illustrating another variation of the luminous indicator illustrated in FIG. 29;

[0057] FIG. 41 is a cross-sectional view illustrating another variation of the luminous indicator illustrated in FIG. 29;

[0058] FIG. 42 is a plan view illustrating the luminous indicator illustrated in FIG. 29;

[0059] FIG. 43 is a plan view illustrating a variation of the luminous indicator illustrated in FIG. 41;

[0060] FIG. 44 is a front view illustrating a main portion of an indicating instrument according to a fifth embodiment of the present invention;

[0061] FIG. 45 is an exploded view illustrating main portions of a dial plate, a light conducting plate, a holder and a liquid crystal panel of the indicating instrument cut along a pair of lines 45—45 in FIG. 44;

[0062] FIG. 46 is a front view illustrating a main portion of an indicating instrument according to a sixth embodiment of the present invention;

[0063] FIG. 47 is a cross-sectional side view cut along a pair of lines 47—47 illustrated in FIG. 46;

[0064] FIG. 48 is a schematic view illustrating a main portion of an indicating instrument according to a seventh embodiment of the present invention; and

[0065] FIG. 49 is a circuit diagram for driving a cold cathode fluorescent lamp and a heater.

[0066] Preferred embodiments will be described with reference to appended drawings hereafter.

[0067] (First Embodiment)

[0068] FIG. 1 and FIG. 2 illustrate an indicating instrument according to a first embodiment of the present invention. The instrument has a dial plate unit 10, which is composed of a dial plate, a straight cold-cathode-fluorescent lighting tube or lamp 10b,a light conducting plate 10cand a holder 10d.

[0069] The dial plate 10aaccording to this embodiment composes an instrument panel disposed in the compartment of a vehicle. The dial plate 10ahas a number of patterned trans-illuminous portions 11a,11b,11cand 11dwhich are stamped out from a transparent plate whose front surface is covered with a dark layer (hereinafter referred to as the surface of the dial plate 10a).

[0070] The patterned trans-illuminous portion 11ais composed of an arc-shaped graded scale pattern indicating the engine rotational speed and a unit pattern indicating the unit of the rotational speed (e.g.×1000 RPM). The patterned trans-illuminous portion 11bis composed of an arc-shaped graded scale pattern indicating the vehicle speed and a units pattern indicating the unit of the vehicle speed (e.g. km/h). The patterned trans-illuminous portion 11cis composed of an arc-shaped graded scale pattern indicating the cooling water temperature and a symbol mark indicating the water temperature. The patterned trans-illuminous portion 11dis composed of an arc-shaped graded scale pattern indicating an amount of fuel and a symbol mark indicating the fuel. The patterned trans-illuminous portions 11a,11b,11cand 11daltogether are indicated by a reference character L in FIG. 2. Portions of the surface of the dial plate other than the trans-illuminous portion L compose opaque portions covered with the black layer.

[0071] The cold-cathode-fluorescent lamp 10bis disposed longitudinally at an upper portion on the back of the dial plate 10aas shown in FIG. 1 and FIG. 2. A tape-like heater 12 is attached to a surface of the fluorescent lamp 10bas shown in FIG. 3 to heat the fluorescent lamp 10bwhen it is colder than a designated temperature. The full length of the fluorescent lamp 10bcorresponds to the total length of the trans-illuminous portion indicated by L. The outer diameter of the fluorescent lamp 10bis preferably about 3 mm in view of the reduced thickness of the dial plate unit 10 and luminosity efficiency thereof.

[0072] The light conducting plate 10cis made of transparent material such as acrylic resin or polycarbonate and disposed on the back of the dial plate 10aadjacent to the cold cathode fluorescent lamp 10bas shown in FIG. 1 and FIG. 3. An upper end surface of the light conducting plate 10cis disposed in parallel with the fluorescent lamp 10bto face the lighting surface thereof. The light conducting plate 10chas an upper half flat portion as thick as 5 mm and a lower half portion which has beveled back surface from the center to the bottom. A frosted surface is formed on the back of the light conductive plate 10cto diffuse the light in the plate 10c.The frosted surface at portion close to the lamp 10bis formed to be rougher than the surface at portions remote from the lamp 10b.The total reflection of the light can be also utilized instead of the frosted surface.

[0073] Light which is emitted by the cold cathode fluorescent lamp 10binto the light conductive plate 10cfrom an upper end 13athereof is diffused by the frosted surface and is guided by the beveled back surface of the light conducting plate 10c,and enters the patterned trans-illuminous portions 11a,11b,11cand 11d.

[0074] The holder 10dis formed from a light-shielding material in a shallow flat pan or tray shape to accommodate the cold cathode fluorescent lamp 10band the light conducting plate 10cand fixed to the dial plate 10a.The indicating instrument has respective indicators for indicating the engine rotational speed (RPM), the vehicle speed; the cooling water temperature and the fuel amount and their driving unit. However, only an indicator 20 for the engine rotational speed and its driving unit 30 are illustrated in FIG. 1 and FIG. 2.

[0075] The driving unit 30 has two flange portions 31, which are fixed to corresponding projecting portions 14aformed on an outer surface of the holder 10dby screws. An indicator shaft 33 extends from the driving unit 30 and is inserted into a cylindrical opening 14bof the holder 10dand a through hole 11eof the dial plate 10a.The through hole 11eis located at a central portion of the arc-shaped graded scale pattern of the patterned trans-illuminous portion 11a.An outer periphery of the cylindrical opening 14bis disposed in a through hole 13cof the light conducting plate 10c.The indicator 20 has a boss 21, which is fitted to the indicator shaft 33 to rotate together.

[0076] Other indicators and driving units of the speedometer, temperature gauge, and fuel gauge are installed into the respective patterned trans-illuminous portions 11b,11cand 11dwhich have through holes 11f,11gand 11hcorresponding to the through hole 11ein substantially the same manner as the indicator 20 and the driving unit 30. The light conducting plate 10calso has through holes (not shown) and the holder 10dhas cylindrical openings (not shown), at portions corresponding to the through holes 11f,11gand 11h.

[0077] When the cold cathode fluorescent lamp 10bemits light, the light enters the inside of the light conducting plate 10cfrom the upper end surface 13a.The light is reflected and diffused effectively by the frosted surface 13band enters the inside of the dial plate 10aequally over the entire portions and passes across the patterned trans-illuminous portions 11a,11b,11cand 11d.

[0078] As a result, the patterned trans-illuminous portions 11a,11b,11cand 11dare illuminated evenly with high contrast between the patterned trans-illuminous portions 11a,11b,11cand 11dand the background portions, providing high visibility of meters and gauges.

[0079] Since the fluorescent lamp 10band the light conducting plate 10care disposed on the same surface behind the dial plate 10a,the dial plate unit 10 can be made very thin. As a result, the indicator shaft can be made short, thereby improving the response time and accuracy of the indication.

[0080] Since the single and straight cold cathode fluorescent lamp 10bis used to illuminate the dial plate 10c,the indicating instrument can be made simple at a reduced cost.

[0081] Since the single light conducting plate 10cis used for conducting the light from the fluorescent lamp 10a,the number or the shape of the patterned trans-illuminous portions can be changed easily by changing the number and position of the through holes.

[0082] FIG. 4 illustrates a variation of the first embodiment. The dial plate 10aof this variation has slanted upper corners and the cold cathode fluorescent lamp is bent to lie along the periphery of the dial plate as shown in FIG. 4. Other portions are the same as the first embodiment.

[0083] FIG. 5 illustrates a second variation of the first embodiment. A pair of cold cathode fluorescent lamps 10B and 10C are used in this variation instead of the single lamp 10bof the first embodiment. The lamp 10B illuminates the patterned trans-illuminous portions 11aand 11c,and the lamp 10C illuminates the patterned trans-illuminous portions 11band 11d.Other portions are the same as the first embodiment. If the dial plate 10ahas a triangular upper portion as shown in FIG. 6, the cold cathode fluorescent lamp 1B and 10C are disposed along the sides of the triangular portion.

[0084] FIG. 7 and FIG. 8 illustrate a third variation of the first embodiment. A pair of cold cathode fluorescent lamps 10D and 10E are disposed at both sides of the dial plate 10ato sandwich the patterned trans-illuminous portions 11c,11a,11band 11d.The left side surface of the light conducting plate 10efaces closely to the fluorescent lamp 10D and the right side surface thereof faces closely to the lamp 10E. The conducting plate 10ehas slopes 15cgradually inclining from both sides of a longitudinally central portion of the light conducting plate 10eand forming a shallow V-shaped valley, and a frosted back surface as shown in FIG. 8.

[0085] The light emitted from the cold cathode fluorescent lamp 10D enters the light conducting plate 10efrom the left side surface 15a,and is guided by the left slopes, reflected and diffused by the frosted surface 15dand enters the patterned trans-illuminous portions 11aand 11c.The light emitted from the cold cathode fluorescent lamp 10E enters the light conducting plate 10efrom the right side surface 15b,and is guided by the right slope, reflected and diffused by the frosted surface 15dand enters the patterned trans-illuminous portions 11band 11d.Other portions are the same as the first embodiment.

[0086] The light conducting plate 10eof the third variation can be divided into two sections along the valley to simplify manufacture of the plate 10e.One cold cathode fluorescent lamp can be omitted in this case if one of the lamps 10D and 10E is placed between the two sections of the light conducting plate 10eand if the side surfaces 15aand 15bof the plate sections are disposed to face the lamp closely.

[0087] FIG. 9 and FIG. 10 illustrate a fourth variation of the first embodiment. A light conducting plate 10fis fixed to the back of the dial plate 10a.The light conducting plate 10fhas a longitudinal groove 11ifor accommodating the cold cathode fluorescent lamp 10b.The longitudinal groove 11iis located between the though holes 11e,11f,11gand 11hand the upper side of the dial plate.

[0088] An open end of the groove 11ion the dial plate side is closed by a light diffusing plate 11jand the cold cathode fluorescent lamp 10bis disposed in the groove 11i.The light diffusing plate 11jis coated with milky white paint mixed with glass beads. The light conducting plate 10fhas slopes inclining from the groove 11ito the sides of the back of the dial plate 10aand has frosted back surface 16. Other portions are the same as the first embodiment.

[0089] In the above variation, since the diffusing plate 11jreflects and diffuses the direct light of the fluorescent lamp 10b,the difference in the brightness between the diffusing plate 11jand other portions can be reduced.

[0090] Since distance between the fluorescent lamp 10band the patterned trans-illuminous portions is short, the brightness of the dial plate increases. The light conducting plate 10fcan be divided into two sections along the groove 11iin order to make the conducting plate 10feasier to manufacture.

[0091] The light conducting plate 10fcan be replaced by a light conducting plate 10gwhich has a V-shaped bend with a reflecting surface Wa, a light incident surface Wb and a grooved ridge portion to face the cold cathode fluorescent lamp 10bas shown in FIG. 11A. The light emitted by the fluorescent lamp 10benters the light conducting plate 10gfrom the grooved ridge portion and is reflected by the reflecting surface Wa and, thereafter, by both surfaces repeatedly in the total reflection manner until it reaches V-shaped opposite ends a and b of the conducting plate 10g.

[0092] Since the V-shaped bend is formed on the conducting plate 10g,the brightness of the portion near the fluorescent lamp 10bcan be reduced as compared to the conducting plate 10ashown in FIG. 10. The light in the conducting plate 10gcan be focused on a desired portion by changing the shape of the grooved ridge.

[0093] The light incident surface Wb can be replaced by a partially cylindrical light incident surface Wc shown in FIG. 11B. At least one of the reflecting surfaces Wa and Wc can be frosted. If the surface Wc is frosted, the light beams emitted from the lamp 10bare scattered by the surface Wc in the light conducting plate 10g.On the other hand, if the surface Wa is frosted, a portion of the light emitted from the lamp 10bis diffused by the surface Wa and directed to the head portion. Thus difference in brightness between a portion right under the lamp and other portions is reduced.

[0094] The V-shaped bend of the light conducting plate 10gcan be replaced with portions indicated by reference character c or d illustrated in FIG. 12A or FIG. 12B. The light conducting plate 10gis also replaceable to a light conducting plate 10hwhich has a bent end e to face the cold cathode fluorescent lamp 10bas shown in FIG. 12C. The groove 11i(in FIG. 10) can be replaced with a groove 11kwhich has a frosted bottom portion without changing the main function as shown in FIG. 13.

[0095] FIG. 14 and FIG. 15 illustrate a fifth variation of the first embodiment. Arc-shaped slits 11mare formed coaxially with the through holes 11e,11f,11gand 11hof the dial plate 10aat a side opposite the fluorescent lamp 10b.

[0096] When the light of the fluorescent lamp 10benters the light conducting plate 10cand comes to an internal wall of the arc-shaped slit 11m,it is reflected toward the through hole (e.g. 13c). Thus, the light is focused on the through hole 13cand the patterned trans-illuminous portion (e.g. 11a) is illuminated sufficiently.

[0097] Instead of the above structure, V-shaped cut sections 11nhaving arc-shaped sides which are respectively coaxial with the through holes (e.g. 13c) are formed at portions opposite the lamp 10bof the dial plate 10abetween the patterned trans-illuminous portions respectively as shown in FIG. 16 and FIG. 17, achieving substantially the same effect as the above variation.

[0098] FIG. 18 illustrates a sixth variation of the first embodiment.

[0099] A casing 40 has two columns 41 extending from the bottom of the holder 10dand support a printed circuit board 50 by screws 42. The casing 40 has a cylindrical member 43 which accommodates a warning lump 51. A bottom end of the cylindrical member 43 faces the back of the dial plate 10adirectly. When the warning lamp is turned on, a turn signal indicator pattern (not shown) formed on the dial plate 10ais illuminated.

[0100] Since the printed circuit board 50 is housed in an otherwise dead space under the dial plate 10a,the casing can be made compact. Since the printed circuit board 50 is disposed at a certain distance from the fluorescent lamp 10b,circuit elements or parts 52 on the printed circuit board are not affected by the heat generated by the lamp 10b.

[0101] A discharge lamp-type self-luminous indicator or an LED-built-in indicator can be used instead of the indicator 20 of first embodiment.

[0102] A fluorescent pointer member (not shown) illuminated by a black light lamp fixed on an upper portion of the dial plate 10acan be used in replacement with the indicator 20 of the first embodiment.

[0103] FIG. 19 illustrates a seventh variation of the first embodiment. The light conducting plate 10cand the holder 10bof the first embodiment are replaced with a light conducting plate 10iand an annular reflecting plate 10j.

[0104] The light conducting plate 10jhas a pair of columnar members to which flanges 31 of the driving unit 30 are bolted.

[0105] The reflecting plate 10jis formed on the back of the light conducting plate 10iby insert-molding, hot stamping or printing to reflect the illumination light toward the dial plate 10aeffectively.

[0106] In order to equalize the illumination of the dial plate, a large number of small black points can be printed on the reflecting plate 10j.The density of the black point increases to reduce the reflectivity as the distance from the fluorescent lamp becomes shorter.

[0107] Instead of reducing the density of the black points at portions remote from the lamp, a number of white or bright colored point can be printed to increase the reflection therefrom.

[0108] (Second Embodiment)

[0109] FIG. 20 and FIG. 21 illustrate an indicating instrument for a vehicle according to a second embodiment of the present invention.

[0110] The indicating instrument has a dial plate unit 60, which is secured to a casing 70 in an open space 71 via an annular light shield 80 having black painted inner surface, and a light conducting plate 60aon the back of the dial plate 10a.

[0111] The annular light shield 80 is composed of an annular flange 81, an inner annular wall 82 extending inside the casing 70 and outer annular wall 82′ extending outward from the annular flange 81. An outer open end of the outer annular wall 82′ has a transparent acrylic resinous front panel 83.

[0112] The dial plate 10ais fixed to an open end of the inner annular wall 82 so that the patterned trans-illuminous portion (e.g. 11a) of the dial plate 10ais exposed to the outside through the front panel 83.

[0113] The light conducting plate 60ais made of the same material as the light conducting plate 10cof the first embodiment. The light conducting plate 60ahas a sloped and saw-toothed back surface approaching the back of the dial plate 10afrom a bottom surface 61 to an upper surface 62 so as to equalize the illumination of the dial plate 10a.

[0114] A light source unit 90 is disposed right under the dial plate unit 60 and fixed to the open end portion 71 of the casing 70 to face the bottom surface 61 of the light conducting plate 60a.The light source unit 90 has a reflector 90a,a convex lens 90band the cold cathode fluorescent lamp 10band the heater 12, which are described before.

[0115] The reflector 90ahas the same longitudinal length as the fluorescent lamp 10band is composed of a reflecting member 91 made of white resinous material, such as polypropylene, and three adapters 92 which are made of transparent elastic material such as polyurethane rubber. The reflecting member 91 is composed of a support 91awhich has a T-shaped cross section secured to a hollow portion 72 and a generally a half cylindrical reflecting portion 91b.

[0116] The reflecting portion 91bopens toward the bottom surface 61 of light conducting plate 60aand has grooves 91cformed on its surfaces to receive the adapters 92 therein and fixing frames 91dformed on both side thereof. The cold cathode fluorescent lamp 10bis fitted into the adapters 92 through slits 92awhich open wide when the lamp 10bis inserted therein.

[0117] The convex lens 90bis a half cylindrical lens made of transparent glass or resinous material that has a flat light incident surface fixed to the open end of the reflecting portion 91band hook members 93 formed on both sides thereof to engage the fixing frames 91dof the reflecting portion 91b.

[0118] When the light source 90 is assembled, the cold cathode fluorescent lamp 10band the heater 12 are inserted into the adapters 92. Then the adapters 92 with the lamp 10band the heater 12 in a unit are inserted into the grooves 91c.Thereafter, the hook members 93 of convex lens 90bare fitted to the fixing frames 91dso that the incident surface of the lens 90babuts on the open end surface of the reflecting portion 91b.As a result, the light of the fluorescent lamp 10bis reflected by the reflecting portion 91b,refracted by the convex lens 90band enters the bottom surface 61 of the light conducting plate 60aas the parallel light as shown in FIG. 22. The T-shaped support 91ais fixed to the hollow portion 72 of the casing 70 and retained by a tongue member 81awhich extends from the annular flange 81. Since the adapters 92 are transparent, the light reflected by the reflecting member 91 is utilized effectively.

[0119] A separate light conducting member or prism 100 made of transparent optical-resinous-material, such as acrylic resin or polycarbonate, is disposed at a front bottom portion of the casing 70 between an inner-front light shield member 84 and the outer light shield member 82 so that a part of the light of the fluorescent lamp 10bis introduced to the prism 100 and illuminates the indicator 20 through a window 84aof the inner front shield member 84 as described later. For this purpose, the prism 100 has a beveled reflecting surface 101 facing the indicator 20. The opposite end of the prism 100 faces a slit 91eformed longitudinally in the reflecting portion 91bof the reflector 90a.

[0120] The indicator instrument has a driving unit 30A housed in the casing 70 and secured by screws 74 to supports 73 formed integrally with the casing. An indicator shaft 34 of the driving unit 30A is inserted in a through hole 64 of the light conducting plate 60 and the through hole 11eof the dial plate 10aand fitted to the boss 21 of the indicator 20.

[0121] Other indicators and driving units for the speedometer, the cooling water temperature gauge and the fuel gauge are substantially the same as the indicator 20 and the driving unit 30A and are fixed to the patterned trans-illuminous portions 11b,11cand 11dof the dial plate 10arespectively.

[0122] Since a part of the light emitted from the cold cathode fluorescent lamp 10bis utilized to illuminate the indicator 20, an expensive self-luminous indicator or an extra cold cathode fluorescent lamp for illuminating the indicator 20 is not necessary to the above embodiment. As a result, an inexpensive highly illuminated indicator instrument can be provided.

[0123] The convex lens 90bof the second embodiment can be omitted if the flat bottom surface 61 of the light conducting plate 60ais changed to a half cylindrical convex surface 61ato form the incident light into parallel light as illustrated in FIG. 23.

[0124] If the transparent front panel 83 is replaced with a smoked panel having a transparency less than 30%, the indicator instrument can have a function so called “black face” through which the dial plate or other inside member is not visible when the lamp is turned off, that is, when the key switch is turned off.

[0125] If the light conducting plate 60ais colored with a color different from the prism 100, the illumination color of the dial plate can be made different from the illumination color of the indicator 20.

[0126] (Third Embodiment)

[0127] FIG. 24 illustrates an indicating instrument for a vehicle according to a third embodiment.

[0128] The dial plate unit 10 and the indicator 20 of the first embodiment are replaced with a dial plate unit 100A, adapter 110 and an luminous indicator 120. The dial plate unit 100A includes a flat reflector 101A, a light diffusing plate 102 and a U-curved gutter-like reflector 103 as well as the dial plate 10a,the cold cathode fluorescent lamp 10band the light conducting plate 10c.

[0129] The flat reflector 101A is attached on the back of the light conducting plate 10cto reflect the light otherwise going out from the light conducting plate 10c.The light diffusing plate 102 is attached on the front surface of the light conducting plate 10cto diffuse the light entering the dial plate 10afrom the light conducting plate 10c.

[0130] The U-curved reflector 103 is fixed to an upper end of the light conducting plate 10aso that the reflecting surface thereof faces the upper end surface 13aof the light conducting plate. The cold cathode fluorescent lamp 10bis disposed in the U-curved reflector so that the light emitted from the lamp 10bis reflected and enters the light conducting plate 10cfrom the upper end surface 13a.The dial plate 10aand the light conducting plate 10care fixed together in a common manner.

[0131] The driving shaft 33 is connected to the driving unit 30 which is described before. The adapter 110 molded from the same material as the light conducting plate 10cwhich is described before and has a center column 111 and an annular grip member 112 as shown in FIG. 24. The center column 111 is composed of a boss portion 111aconnected to the driving shaft 33 and a cone-shaped support portion 111bwhich supports the indicator 120 with the grip member 112 to connect the luminous indicator 120 to the driving shaft 33. For this purpose, the grip portion extends from the center column 111 to form an L-shape in a cross-section having arc-shaped lips 112aextending inward therefrom at an equal interval.

[0132] The luminous indicator 120 is a mold of the same material as the light conducting plate 10cand has a columnar support 121, a pointer which extends radially from the columnar support 121, a center hole 121ahaving a cone-shaped bottom 121bto receive the cone-shaped support portion 111bof the adapter 110, a pair of arc-shaped projections 121cwhich are formed on the outer periphery of the columnar support 121 to be caught by the grip member 112 of the adapter 110 and an annular groove 121dwhich receives the lips 112aof the adapter 110. The bevel angle of the cone shaped bottom of the luminous indicator 120 and the cone shaped support portion 111bof the adapter 110 is about 45 degrees. On the base portion of the pointer which is opposite the center hole 121a,a beveled reflecting surface 121eis formed so that the light in the columnar support 121 is reflected toward the pointer 122. The beveled reflecting surface 121ecan be replaced with a curved surface or a stepped surface. The outer surface of the indicator 120 is frosted or covered with light diffusing coating so that the indicator can be illuminated uniformly. A reference numeral 123 indicates a cap fixed to the pointer to prevent the light from leaking from the pointer.

[0133] When the luminous indicator 120 is connected to the adapter 110, the columnar support 121 is put into the through hole 13cof the light conducting plate 10cthrough the holes 11eand 102aof the dial plate 10aand the light diffusing plate 102. Then the cone-shaped support portion 111 of the adapter 110 is fitted into the center hole of the columnar support 121 of the indicator 120, and the projections 121care put into the grip member 112 of the adapter 110 through gaps formed between the lips 112a.

[0134] Thereafter, the adapter 110 is turned slightly around the columnar support 121 so that the projections 121care secured between the lips 112aand the bottom portion of the grip member 112.

[0135] When the light of the cold cathode fluorescent lamp 10benters the light conducting plate 10cfrom the upper surface 13c,it is diffused by the light diffusing plate 102 on its way and guided to the dial plate 10a.Thus, the patterned trans-illuminous portions of the dial plate 10aare illuminated as described with regard to the first embodiment.

[0136] At the same time, a part of the light guided by the light conducting plate 10centers the indicator 120 from the columnar support 121 as indicated by chain lines illustrated in FIG. 25. The light coming into the indicator 120 is reflected by the cone-shaped bottom 121btoward the beveled reflecting surface 121e,where the light is reflected toward the pointer 122 for illumination. When the pointer 122 points upward as shown by the chain lines in FIG. 25, the light guided along the periphery of the columnar support 121 reaches the head portion of the pointer 122. On the other hand, when the pointer points downward as shown in FIG. 25, the light guided along the center axis of the columnar support 121 reaches the head portion of the pointer 122.

[0137] Thus, an additional light emitting element such as an LED or a cold cathode fluorescent lamp, is not necessary to illuminate the indicator.

[0138] Since the driving shaft 33 is located outside the through hole 13cof the light conducting plate 10c,the light entering the pointer 122 is guided along the indicator to the head of the pointer without any obstacle. As a result, the illumination of the dial plate 10aand the indicator can be provided without increasing cost.

[0139] The adapter 110 can be omitted if the driving shaft 33 is directly connected to the columnar support 120 as indicated by chain lines in FIG. 25 and 26.

[0140] The illumination of the indicator 120 of the third embodiment can be increased if a W-shaped light reflecting slit 13dis formed in the light conducting plate 10cat the side of the through hole 13copposite the fluorescent lamp 10bas illustrated in FIG. 27A and FIG. 27B. An additional part of the light from the lamp 10bis reflected by the surface of the W-shaped reflecting slit 13dand guided to the through hole 13ctogether with the direct light. The W-shaped slit can be replaced with a parabolic slit 13eas illustrated in FIG. 28.

[0141] (Fourth Embodiment)

[0142] FIG. 29 and FIG. 30 illustrate an indicating instrument for a vehicle according to a fourth embodiment of the present invention. A dial plate unit 200 and a luminous indicator 210 are used instead of the dial plate unit 10 and the indicator 20 of the first embodiment. The dial plate unit 200 is composed of the dial plate 10aof the first embodiment 10a,the cold cathode fluorescent lamp 10bof the first embodiment, and a different light conducting plate 201.

[0143] The indicator 210 molded from the same material as the light conducting plate 10c.A base portion 210aof the indicator 210 has beveled reflecting surfaces 213 and 214, which are covered by a light shield cover 211.

[0144] The light conducting plate 201 guides the light emitted from the lamp 10bthrough a beveled reflecting surface 201ato the indicator 210. The light guided into the indicator 210 is reflected by the beveled reflecting surfaces 213 and 214 toward the head of a pointer 210bas indicated by arrows La and Lb to illuminate the indicator.

[0145] If the light conducting plate is made of colored material, the dial plate 10acan provide colored illumination.

[0146] FIG. 31 illustrates a variation of the fourth embodiment. the light conducting plate 201 is replaced with a pair of light conducting plates 202 and 203. The driving unit 30 of the first embodiment is replaced with a driving unit 30B. The light conducting plate 202 guides the light of the cold cathode fluorescent lamp 10bto the dial plate la as described before. The light conducting plate 203 is disposed apart from the plate 202. The plate 203 has beveled reflecting surfaces 203aand guides the light emitted from the lamp 10bto the base portion 210aof the indicator 210 ( shown in FIG. 29) as indicated by an arrow Lb in FIG. 31.

[0147] The light conducting plate 203 can be disposed in contact with the light conducting plate 202 as illustrated in FIG. 32.

[0148] The light conducting plate 203 can be replaced with a light conducting plate 204 as illustrated in FIG. 33. The light conducting plate 204 has a reflecting surface for turning light back in addition to a beveled reflecting surface at a portion near the cold cathode fluorescent lamp 10bso as to guide the light toward the indicator 210 as indicated by arrows Lc and Ld.

[0149] This variation utilizes the light of the cold cathode fluorescent lamp 10bmore effectively.

[0150] The light conducting plates 202 and 203 of the variation illustrated in FIG. 32 are replaced with light conducting plates 205 and 206 shown in FIG. 34. The functions of both plates 205 and 206 are substantially the same as the variation illustrated in FIG. 32. In this variation, the light in the plate 206 is guided as indicated by an arrow Le. Reference numerals 206a,206band 206cindicate beveled reflecting surfaces respectively.

[0151] Since the light conducting plate 206 has a central recess in this variation, thickness of the indicating instrument is reduced.

[0152] The light conducting plate 201 of the fourth embodiment illustrated in FIG. 29 is replaced with a light conducting plate 207 as illustrated in FIG. 35 and FIG. 36. The light conducting plate 207 has a generally rectangular through hole 207ainstead of the circular hole to receive the columnar support 212 (shown in FIG. 35). A beveled reflecting surface 207bis formed at a side of the rectangular through hole 207afacing the fluorescent lamp 10bso that the light guided from the lamp 10bis guided along an arrow indicated by Lf toward the indicator 210.

[0153] Other beveled reflecting surfaces 207e,207f,207g,207h207iand 207jare also formed around the rectangular through hole to guide the light of the lamp 10balong arrows Lg, Lh, Li, Lj, Lk and Lm. Two diagonal slits 207cand 207dare formed in the light conducting plate 207 to provide reflecting surfaces in the optical paths indicated by the arrows Lg, Li, Lh and Lj as illustrated in FIGS. 36, 37 and 38.

[0154] The above variation utilizes the light emitted by the cold, cathode fluorescent lamp more effectively.

[0155] FIG. 39 and FIG. 40 illustrate other variations of the indicator 210.

[0156] An indicator 220 has curved reflecting surfaces 221 and 222. Another indicator 230 has a flat reflecting surface 231 which corresponds to the reflecting surface 213 shown in FIG. 29 and a plurality of flat reflecting surfaces 232, 233 and 234 which corresponds to the reflecting surface 214 shown in FIG. 29. The reflecting surfaces 233 and 234 are formed symmetrically on the indicator 230.

[0157] The indicator 210 of the fourth embodiment can be replaced with a luminous indicator 240 as illustrated in FIG. 41 and FIG. 42.

[0158] The indicator 240 has a pointer which is shorter than the indicator 210 and has a light shield cover 241 (which corresponds to the cover 211) on its base portion. Only one beveled reflecting surface 242 is formed on the base portion of the indicator 240. Other portions are the same as the fourth embodiment. The luminous indicator 240 can be replaced with an indicator 250 with a cover 251 as shown in FIG. 43.

[0159] (Fifth Embodiment)

[0160] FIG. 44 and FIG. 45 illustrate an indicating instrument according to a fifth embodiment of the present invention. The light conducting plate 10cand the pattern indicating the unit of the vehicle speed (e.g. km/h) of patterned trans-illuminous portion 11bof the first embodiment is replaced with a light conducting plate 130 and an odometer 140 composed of a transmission-type liquid-crystal-display.

[0161] The light conducting plate 130 has a rectangular recess 131 at a portion corresponding to an opening 11pof the dial plate 10a,where the odometer 140 is fixed as illustrated in FIG. 45. The liquid crystal display of the odometer 140 is illuminated by a part of the light guided in the light conducting plate 10a.

[0162] (Sixth Embodiment)

[0163] An indicating instrument according to a sixth embodiment of the present invention is described with reference to FIG. 46 and FIG. 47.

[0164] The dial plate unit 10 of the first embodiment is replaced by a dial plate unit 300 as illustrated in FIG. 46.

[0165] The dial plate unit 300 has a pair of dial plates 310 and 320 and a gear shift indicator 300atherebetween. The indicator 300ahas a narrow light conducting plate 330 made of the same material as the conducting plate 10c.The light conducting plate 330 has a beveled reflecting surface 331 at an upper end thereof as illustrated in FIG. 47 to reflect the light guided thereto downward.

[0166] The indicator 300ahas a light shield casing 340 which is fixed to the back of the light conducting plate 330, a plurality of cylindrical members 344 with lamps 380aand a flat indicator lens 350 which covers the cylindrical members 344. The light shield casing 340 has L-shaped light shield cover 342 covering a part of the cold cathode fluorescent lamp and the beveled reflecting surface 331. The cover 342 has an open end 342aexposed to the front outside as illustrated in FIG. 47. A plurality of colored symbols 360acorresponding to the gear positions (e.g. P, R, N, D, 2, L) are printed on the indicator lens 350 at portions corresponding to the respective cylindrical members 344 as shown in FIG. 46. Portions surrounding the colored symbols 360aare covered by a printed opaque coating 370 to shield the light. Thus, each of the colored symbols is illuminated when the corresponding lamp is turned on.

[0167] (Seventh Embodiment)

[0168] An indicator instrument according to a seventh embodiment of the present invention is described with reference to FIG. 48 and FIG. 49. The tape-like heater 12 of the first embodiment is replaced with coiled heater 400 wound around the cold cathode fluorescent lamp 10b.The heater 400 is a wire made of a ferrite alloy of about 0.15 mm in diameter which is composed of chromium (22%), aluminum (4.8%), and iron (73.2%). An end 401 of the heater 400 is grounded and the other end is connected to a battery Ba through a switching element 411 of a heater circuit 410 and a key switch IG. The heater circuit 410 turns on the switching element 411 when temperature of the cold cathode fluorescent lamp 10bis detected to be lower than a designated temperature and supplies electric power to the heater 400 from the battery Ba. A light source circuit energizes the cold cathode fluorescent lamp 10b.Other portions are the same as the first embodiment.

[0169] Since the heater 400 is grounded, the radio noise (mainly AM-band radio frequency) can be absorbed by the heater. Since the heater is wound around the lamp 10b,it functions as a supplementary electrode to lower the driving voltage.

[0170] The patterned trans-illuminous portions can be formed directly on the conducting plate 10cinstead of the dial plate 10a.Other straight lamps can be replaced with the cold cathode fluorescent lamp 10b.The trans-illuminous portions and the other opaque portions of the dial plate 10aof the indicating instruments according to the previously described embodiments can be replaced with each other so that the indicator and the dial scales remain dark in the illuminated back surface.

[0171] The indication instrument according to the present invention can be used for various purposes other than vehicles.

[0172] In the foregoing description of the present invention, the invention has been disclosed with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific embodiments of the present invention without departing from the broader spirit and scope of the invention as set forth in the appended claims. Accordingly, the description of the present invention in this document is to be regarded in an illustrative, rather than restrictive, sense.