JP6105406B2 - Light guide plate and instrument - Google Patents

Description

  The present invention relates to a light guide plate disposed behind a dial plate of an automobile instrument or the like, and an instrument using the light guide plate.

  As this type of light guide plate, there is known a light guide plate having a circular arc shape in front view that guides light from a light source incident from an end face in the circumferential direction so that the dial is illuminated from the back. Patent Document 1 describes a light guide plate in which an arc-shaped groove is formed in front of a light guide plate having a circular arc shape when viewed from the front.

  16 is a perspective view seen from the front of a conventional light guide plate similar to the light guide plate described in Patent Document 1, and FIG. 17 is an enlarged view of a portion E in FIG.

  The light guide plate 210 shown in FIG. 16 is provided between a dial plate (not shown) and a diffuse reflection plate (not shown) provided behind the dial plate, and is formed in a circular arc shape when viewed from the front. Is arranged on the back surface of the dial with the front facing the light, and guides the light from the light source incident from the light incident end surface 218 provided at the circumferential end of the arc shape so that the dial is illuminated from the back surface. It has become.

  This light guide plate 210 connects the illumination main body 216 having a light emission surface 216A facing the back of the dial face in the front, the light incident end surface 218 and the illumination main body 216, and is incident on the light incident end surface 218. A light guiding portion 217 that guides the illumination main body portion 216 to the light emission surface 216A of the illumination main body portion 216, extending along the arc shape and spaced in the radial direction of the arc shape. And a large number of arc-shaped grooves 211 formed. In addition, a radial groove (not shown) is formed on the back surface of the illumination main body 216.

  The light guiding portion 217 is curved toward the back side of the light guide plate 210 from the illumination main portion 216 side toward the light incident end surface 218. Further, the surface 217A of the light guiding portion 217 and the light emitting surface 216A of the illumination main portion 216 are formed as the same surface that is smoothly continuous without a step, and the end surface 211t of the arc-shaped groove 211 is formed on the light guiding portion 217. It is located inside the circumferential direction of the surface 217A.

JP 2011-40367 A

  18A and 18B are cross-sectional views of a portion from the light guiding portion 217 to the illumination main portion 216. FIG. 18A is a cross-sectional view at a position where the arc-shaped groove 211 is not present, and FIG. It is sectional drawing in a certain position.

  The light L incident from the light incident end face 218 is reflected by the convexly curved surface 217A of the light guiding portion 217 and travels in the direction of the illumination main portion 216. At that time, in the path where the end face 211t of the arc-shaped groove 211 is not provided in the path of the light L, the light L travels as it is inside the light guide plate 210 as shown in FIG. In the path where the end face 211t of the arc-shaped groove 211 is in the path of the light L, the light L is on the end face 211t (interface between the material of the light guide plate 210 and air) of the arc-shaped groove 211 as shown in FIG. The light enters and refracts, leaks out of the light guide plate 210, and becomes light directly directed to the dial. The light leaked at a position close to the light source causes the dial to shine strongly, which causes luminance spots.

  FIG. 19 shows a simulation result of luminance viewed from the front of a conventional light guide plate. The light incident from the light incident end surface 218 exhibits a brightness higher than the surroundings at the incident point or the arcuate circumferential end, but at the position of the end surface 211t (see FIG. 18) of the arc-shaped groove 211, the light is higher than that. Shows high brightness. In FIG. 18, F is a location that exhibits a higher brightness than the surroundings, and Fx is a location that exhibits a higher brightness. There is no problem at the incident point or the circumferential end of the arc shape even if the luminance is somewhat high, because there is no problem because the light does not travel directly to the dial, but the end surface 211t of the arc-shaped groove 211 (see FIG. 18). The high brightness at the position causes brightness spots when the dial is illuminated.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to eliminate a luminance unevenness in the vicinity of the light source as much as possible, and to illuminate the dial from behind with uniform light, and Another object of the present invention is to provide an instrument using the light guide plate.

The above object of the present invention can be achieved by the following constitution.
(1) The light from the light source that is formed in a curved shape in front view, is disposed on the back surface of the dial with the plate surface facing the front, and is incident from a light incident end surface provided at an end of the curved shape, A light-transmissive light guide plate that guides the dial so that it illuminates from the back,
An illumination main body having a light-emitting surface facing the back of the dial in front, and connecting the light incident end face and the illumination main section to guide the light incident on the light incident end face to the illumination main section. A light guiding part,
A large number of curved ridges are formed on the light emitting surface of the illumination main body along the curved shape and spaced in a direction perpendicular to the extending direction,
The light guide plate, wherein an end face on the light incident end face side of the curved ridge is positioned outside a surface of the light guiding portion that smoothly continues as the same surface as the light emitting surface.

  (2) The light guide plate according to (1), wherein the light guide portion is curved toward the back side of the light guide plate from the illumination main body side toward the light incident end surface.

(3) An air layer formed between the dial and the diffuse reflector, formed in a circular arc shape when viewed from the front, between the dial in front and the diffuse reflector disposed on the back of the dial. Placed through
A large number of arc-shaped ridges extending along the circumferential direction of the arc shape and spaced in the radial direction of the arc shape on the light emitting surface of the illumination main body as the curved ridges. And a large number of radially extending along the radial direction of the arc shape and spaced apart in the circumferential direction of the arc shape on the back surface of the illumination main body facing the diffuse reflector The light guide plate according to (2), wherein the light guide plate has radial ridges.

  (4) The distance between the radial ridges is set so as to gradually decrease as the distance from the light incident end surface on which light from the light source is incident is set. Light guide plate.

(5) The light guide plate according to (3) or (4) is disposed between the dial plate and the diffuse reflector, with an air layer interposed between the dial plate and the diffuse reflector, respectively. Instrument,
A measuring instrument, wherein a recess for securing the air layer on the back surface of the light guide plate is provided on at least one of the back surface of the light guide plate and the front surface of the diffuse reflection plate facing each other.

(6) The light guide plate according to (3) or (4) is disposed between the dial plate and the diffuse reflector, with an air layer interposed between the dial plate and the diffuse reflector. An instrument,
An instrument, wherein a spacer for securing the air layer on the back surface of the light guide plate is sandwiched between the back surface of the light guide plate and the front surface of the diffuse reflection plate facing each other.

  According to the light guide plate having the above configuration (1), a curved ridge is formed on the light-emitting surface of the illumination main portion instead of a groove as in the conventional example, and the end surface of the curved ridge is Since it is located outside the surface of the light guide part, the light traveling through the light guide part does not enter the end face of the curved ridge, that is, enters the end face as in the case of a groove and externally Proceed into the lighting main part without leaking into the main body. Accordingly, since strong light does not leak toward the dial at a position close to the light source, the dial is not partially shined strongly, and luminance spots can be reduced. Further, since the curved ridge formed on the light emitting surface can guide light far as in the case of the groove, the luminance of the entire dial can be made uniform.

  According to the light guide plate having the configuration (2), the direction of the light incident on the light incident end surface can be changed to face the illumination main body by the curved light guiding portion.

  According to the light guide plate having the configuration (3), the arcuate ridge is formed on the light emitting surface of the illumination main body and the radial ridge is formed on the back surface of the illumination main body. Can guide a lot of light along the arc shape of the light guide plate, and can reduce the incident angle of a lot of light incident on the wall of the radial ridges. Can be transmitted to the diffuse reflector. That is, it is possible to reduce the light directly reflected by the walls of the radial ridges, to eliminate luminance spots as much as possible, and to illuminate the dial from behind with uniform light.

  According to the light guide plate having the configuration (4), the distance of light transmission decreases as the distance from the light source increases, but the density of the radial ridges increases as the distance from the light source increases to compensate for this. The distribution of the illumination light quantity in the circumferential direction can be made uniform.

  According to the instrument configured as described in (5) above, an air layer with a constant interval is secured between the light guide plate and the diffuse reflector by the concave portion provided on at least one of the opposing surfaces of the light guide plate and the diffuse reflector. The existence of the air layer can widen the diffuse reflection range of light on the diffuse reflector. Therefore, the illumination range for the dial plate by the light transmitted through the light guide plate can be expanded, which can contribute to the improvement of luminance spots.

  According to the instrument configured as described in (6) above, a spacer is sandwiched between the light guide plate and the diffuse reflector, so that an air layer at a constant interval can be secured between the light guide plate and the diffuse reflector. Due to the presence of the air layer, the diffuse reflection range of light on the diffuse reflector can be expanded. Therefore, the illumination range for the dial plate by the light transmitted through the light guide plate can be expanded, which can contribute to the improvement of luminance spots.

  According to the present invention, the luminance unevenness can be eliminated as much as possible, and the dial can be illuminated from behind with uniform light.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is a front view of an instrument incorporating a light guide plate according to an embodiment of the present invention. 2 is a cross-sectional view taken along arrow AA in FIG. FIGS. 3A and 3B are a perspective view seen from the front and a rear view seen from the back of the light guide plate shown in FIG. FIG. 4 is an enlarged view of a portion B in FIG. 5A is a cross-sectional view taken along the line CC in FIG. 4, and FIG. 5B is a cross-sectional view taken along the line DD in FIG. FIG. 6 is a diagram illustrating a simulation result of luminance when viewed from the front of the light guide plate of the embodiment. FIG. 7 is a perspective view schematically showing an enlarged part of the light guide plate shown in FIG. FIG. 8 is an operation explanatory view of the arc-shaped groove on the front surface of the light guide plate shown in FIG. 3, and FIG. 8 (a) is an explanatory view showing how the light traveling inside the light guide plate travels along the arc-shaped groove. 8 (b) is an explanatory view of an incident angle when the light of FIG. 8 (a) is incident on the radial ridges on the back surface of the light guide plate, and FIG. 8 (c) is a diagram of the light of FIG. It is explanatory drawing which shows a mode that it permeate | transmits a wall. FIG. 9 is an operation explanatory view in the case of the comparative example without the arc-shaped groove on the front surface of the light guide plate shown in FIG. 3, and FIG. 9A is an explanatory view showing the path of light traveling inside the light guide plate. FIG. 9B is an explanatory view of an incident angle when the light of FIG. 9A is incident on the radial protrusion on the back surface of the light guide plate, and FIG. 9C is a part of the light of FIG. It is explanatory drawing which shows a mode that it reflects by the wall of a stripe | line. FIG. 10 is a diagram showing a simulation result for demonstrating the light path of FIG. FIG. 11 is an operation explanatory view of the radial ridges on the back surface of the light guide plate shown in FIG. 3, and FIG. 11 (a) is a diagram showing a state where light traveling inside the light guide plate is transmitted through the walls of the radial ridges; FIG. 11B is a diagram showing a state in which the light of FIG. 11A is diffusely reflected by the diffuse reflector, passes through the light guide plate again, and proceeds toward the dial. 12A is a schematic cross-sectional view showing the diffusion of light when an air layer is secured on the back surface of the light guide plate, and FIG. 12B is a light when no air layer is secured on the back surface of the light guide plate. It is a schematic explanatory drawing which shows spreading | diffusion. FIG. 13A to FIG. 13C are schematic cross-sectional views respectively showing configuration examples for securing an air layer on the back surface of the light guide plate. FIG. 14A to FIG. 14C are diagrams showing variations in the cross-sectional shape of the arcuate ridges. Fig.15 (a)-FIG.15 (c) are figures which show the variation of the cross-sectional shape of a radial protruding item | line. FIG. 16 is a perspective view seen from the front side of a conventional light guide plate. FIG. 17 is an enlarged view of a portion E in FIG. 18A is a cross-sectional view taken along the line FF in FIG. 17, and FIG. 18B is a cross-sectional view taken along the line GG in FIG. FIG. 19 is a diagram showing a luminance simulation result when viewed from the front side of a conventional light guide plate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 is a front view of a meter incorporating the light guide plate of the embodiment, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and FIGS. 3 (a) and 3 (b) are the light guide plates shown in FIG. It is the perspective view seen from the front, and the perspective view seen from the back.

  As shown in FIGS. 1 and 2, the instrument 1 is an instrument (also referred to as a display device) provided on an instrument panel of an automobile, and includes a dial 2 provided with a design such as a warning and a scale, and a dial 2, a pointer 3 provided to rotate in front of the circuit board 2, a casing 4, a circuit board 5 provided behind the dial 2, and a guide provided behind the dial 2 and in front of the circuit board 5. Light plate 10, diffuse reflector 6 provided behind circuit board 5 behind light guide plate 10, light guide plate light source 8 such as LED and warning light source 9 mounted on circuit board 5, dial plate 2 and a front glass 7 covering the front face of 2.

  The light guide plate 10 is provided between the dial plate 2 and the diffuse reflection plate 6 provided behind the dial plate 2, and the front surface (light-emitting surface described later) 16 </ b> B of the light guide plate 10 defines the air layer K. The back surface (back surface) 16B of the light guide plate 10 faces the front surface of the diffuse reflection plate 6 with the air layer K interposed therebetween. The front surface of the diffuse reflector 6 is formed, for example, as a white smooth surface so that light can be diffusely reflected forward. For example, a part of the wall surface formed integrally with the casing 4 is used for the diffuse reflector 6.

  The light guide plate 10 is made of a light-transmitting material such as acrylic resin, and is formed as a smooth plane in which the front surface 16A and the back surface 16B are parallel to each other. Further, as shown in FIG. 3, the light guide plate 10 is formed in a front arc shape (curved shape) along a scale provided on the dial 2, and the outer peripheral surface 14 and the inner peripheral surface 15 are smooth. It is configured as a circular arc surface.

  Further, one end portion in the circumferential direction of the light guide plate 10 is curved toward the circuit board 5 (toward the back surface 10B side of the light guide plate 10) in its own plate thickness direction, and the end surface of the curved portion is guided. A light incident end face 18 on which light from an optical plate light source (light source such as an LED) 8 enters. The light guide plate 10 plays a role of illuminating the scale provided on the dial 2 from behind by guiding light from the light source 8 incident on the light incident end face 18.

  The light guide plate 10 is described by distinguishing the area. The light guide plate 10 has a light emitting surface 16B facing the back surface of the dial 2 in the front, and connects the light incident end surface 18 and the light main portion 16 with each other. A light guiding portion 17 that guides the light incident on the light end face 18 to the illumination main portion 16. The light guiding portion 17 is curved toward the back surface 16B side of the light guide plate 10 from the illumination main body portion 16 side toward the light incident end surface 18.

  As shown in FIG. 3A, the light emission surface 16 </ b> A of the illumination main body 16 of the light guide plate 10 facing the back surface of the dial 2 (see FIG. 2) is along the arc-shaped circumferential direction of the light guide plate 10. A large number of arc-shaped ridges (curved ridges) 11 are formed at regular intervals in the radial direction of the arc shape of the light guide plate 10. Further, as shown in FIG. 3B, the back surface 10B of the illumination main body 16 of the light guide plate 10 facing the diffuse reflector 6 (see FIG. 2) is along the radial direction of the arc shape of the light guide plate 10. A large number of radial ridges 12 extending radially and spaced in the circumferential direction of the arc shape of the light guide plate 10 are formed. The arc-shaped ridges 11 and the radial ridges 12 are in a relationship of intersecting substantially perpendicularly with a thickness of the illumination main body 16 of the light guide plate 10.

  4 is an enlarged view of a portion B in FIG. 3A, FIG. 5A is a sectional view taken along the line CC in FIG. 4, FIG. 5B is a sectional view taken along the line DD in FIG. 6 is a diagram showing a simulation result of luminance when viewed from the front of the light guide plate, and FIG. 7 is a perspective view schematically showing an enlarged part of the light guide plate.

  Since the arc-shaped ridge 11 is formed so as to protrude to the light emitting surface 16A of the illumination main body 16, the end surface 11t on the light incident end surface 18 side of the arc-shaped ridge 11 is as shown in FIG. 4, 5 (a), and 5 (b), the surface 17 </ b> A of the light guiding portion 17 that is smoothly continuous as the same surface as the light emitting surface 16 </ b> A of the illumination main body 16 is more convex than the surface 17 </ b> A. Located on the outside.

  As shown in FIG. 7, the arc-shaped ridge 11 of the light guide plate 10 of this embodiment has a rectangular cross section having both side walls 11a perpendicular to the light emitting surface 16A and an upper wall 11b parallel to the light emitting surface 16A. Is formed. Further, the radial ridges 12 on the back surface 16B of the light guide plate 10 are formed in a triangular cross section having two inclined side walls 12a that obliquely intersect the back surface 16B of the light guide plate 10. Further, as shown in FIG. 3B, the interval at which the radial ridges 12 are arranged is set so as to gradually decrease as the distance from the light incident end face 18 increases (in the direction indicated by the arrow X). Thus, the radial ridges 12 are formed with higher density as the distance from the light incident end face 18 increases.

Next, the operation of the light guide plate 10 having the above configuration will be described.
As shown in FIGS. 5A and 5B, the light guide plate 10 according to the present embodiment has an arcuate convex shape on the light emitting surface 16A of the illumination main body 16 instead of the arcuate groove as in the conventional example. Since the strip 11 is formed, and the end surface 11t of the arc-shaped convex strip 11 is located outside the surface 17A of the light guiding portion 17, the light L traveling inside the light guiding portion 17 is arc-shaped convex. The light enters the illumination main body 16 without entering the end surface 11t of the strip 11, that is, without entering the end surface and leaking outside as in the case of the arc-shaped groove.

  Therefore, strong light does not leak toward the dial 2 at a position close to the light source 8, so that the dial 2 is not partially shined strongly, and luminance spots can be reduced. This can also be confirmed from the simulation results shown in FIG. That is, according to this simulation result, it was confirmed that light having high luminance at the position of the end surface 11t of the arc-shaped ridge 11 disappeared.

  Further, since the arc-shaped ridges 11 formed on the light emitting surface 16A can guide light far as in the case of the arc-shaped grooves, the brightness of the entire dial 2 can be made uniform. . Further, in the light guide plate 10 of the present embodiment, the direction of the light incident on the light incident end surface 18 can be changed to face the illumination main body 16 by the curved light guiding portion 17.

  FIG. 8 is an operation explanatory diagram in the case of the arcuate convex 11 on the light emitting surface 16A of the light guide plate 10, and FIG. . 8 and 9, only one arcuate protrusion 11 and radial protrusion 12 are shown as representatives.

  First, with reference to FIG. 9, a light path in the case where the front surface (light-emitting surface) 16 </ b> A of the light guide plate 10 has no arcuate protrusion 11 [see FIG. 9A] will be described. 9A is an explanatory diagram showing paths of the light L11, L12, and L13 traveling inside the light guide plate 10, and FIG. 9B is a back view of the light guide plate 10 where the light L11, L12, and L13 in FIG. FIG. 9C is an explanatory diagram showing a state in which a part of the light in FIG. 9B is reflected by the wall 12a of the radial ridge 12. is there.

  As shown in FIG. 9A, the light L11 that travels near the outer peripheral surface 14 among the light L11, L12, and L13 incident from the light source 8 into the light guide plate 10 is an outer peripheral surface curved in an arc shape. 14 is incident and reflected at an incident angle θ1 at a position close to the front side of the light traveling direction (lower side in FIG. 9A). The light L12 traveling through the intermediate position between the outer peripheral surface 14 and the inner peripheral surface 15 is incident on the outer peripheral surface 14 curved in an arc shape at a position farther than the light L11 and is reflected. Further, the light L13 traveling near the inner peripheral surface 15 is incident on the outer peripheral surface 14 curved in an arc shape at an incident angle θ1 at a position farther than the lights L11 and L12 and is reflected.

  Therefore, the incident angles with respect to the outer peripheral surface 14 become smaller as the light beams L12 and L13 travel closer to the inner peripheral surface 15 (θ1> θ2> θ3). As a result, the light L11 traveling near the outer peripheral surface 14 is reflected by the outer peripheral surface 14 and travels in the light guide plate 10 substantially along the arc shape. However, the light L12 and L13 traveling on the inner peripheral side are guided. The light is reflected from the outer peripheral surface 14 of the optical plate 10 toward the inner peripheral side of the light guide plate 10 with a small reflection angle, and is difficult to travel along the arc shape of the light guide plate 10.

  For this reason, as shown in FIG. 9B, the light L11 is incident at an angle α1 (corresponding to a small incident angle) substantially perpendicular to the radial ridges 12, but the lights L12 and L13 are radially convex. It does not enter at an angle close to perpendicular to the strip 12 (that is, α2 and α3 are greatly deviated from 90 °, and the incident angle with respect to the radial convex strip 12 is increased). Therefore, although the light that is perpendicularly incident on the radial ridge 12 passes through the side wall 12a of the radial ridge 12, as shown in FIG. 9C, the light L12 and L13 incident at an angle (incident angle). Large light) is reflected inside the light guide plate 10 by the side wall 12a of the radial ridge 12. In this way, when the light L12 and L13 directly reflected by the wall 12a of the radial ridge 12 without being transmitted toward the diffusive reflecting plate 6 travels toward the dial 2, it leads to generation of luminance spots. When it does not advance toward the dial 2, it becomes easy to lead to a decrease in illumination efficiency, and there is a need for improvement.

  Next, with reference to FIG. 8, a light path in the case where the arcuate ridge 11 is provided on the front surface (light emitting surface) 16 </ b> A of the light guide plate 10 will be described. 8A is an explanatory diagram showing paths of the light L11, L12, and L13 traveling inside the light guide plate 10, and FIG. 8B is a back view of the light guide plate 10 where the light L11, L12, and L13 in FIG. FIG. 8C is an explanatory view showing a state in which a part of the light in FIG. 8B is transmitted through the wall 12a of the radial ridge 12. .

  As shown in FIG. 8A, the light L11 that travels closer to the outer peripheral surface 14 among the light L11, L12, and L13 incident from the light source 8 into the light guide plate 10 is an outer peripheral surface curved in an arc shape. 14 is incident and reflected at an incident angle θ1 at a position close to the front side of the light traveling direction (lower side in FIG. 8A). Further, the light L12 traveling through the intermediate position between the outer peripheral surface 14 and the inner peripheral surface 15 is incident on the side wall 11a of the arc-shaped ridge 11 provided on the front surface (light emitting surface) 16A of the light guide plate 10 at an incident angle θ2 and reflected. Is done. Further, the light L13 traveling near the inner peripheral surface 15 is incident on the side wall 11a of the arcuate ridge 11 provided on the front surface (light emitting surface) 16A of the light guide plate 10 at an incident angle θ3 and reflected.

  As described above, the lights L12 and L13 are reflected not by the outer circumferential surface 14 of the light guide plate 10 but by the arc-shaped ridges 11 as in the comparative example of FIG. 9A, so that the light L11 enters the outer circumferential surface 14. The angle θ1, the incident angle θ2 of the light L12 with respect to the arcuate ridge 11 and the incident angle θ3 of the light L13 with respect to the arcuate ridge 11 can be made substantially equal (θ1≈θ2≈θ3). Therefore, the lights L11, L12, and L13 reflected by the outer peripheral surface 14 and the arc-shaped ridges 11 can be made substantially parallel, and any of the lights L11, L12, and L13 can be guided along a substantially arc shape. become able to.

  As described above, it was confirmed from the simulation result shown in FIG. 10 that the light incident from the light incident end face 18 can be guided substantially along the arc shape by providing the arc-shaped ridges 11.

  Therefore, as shown in FIG. 8B, any of the lights L11, L12, and L13 can be incident substantially perpendicularly to the radial ridges 12 (α1≈α2≈α3≈90 °), and FIG. As shown to c), many light L11, L12, L13 can permeate | transmit the side wall 12a of the radial protruding item | line 12, and can inject into the diffuse reflection board 6. FIG.

  FIG. 11 is an operation explanatory view of the radial ridges 12 on the back surface 16B of the light guide plate 10, and FIG. 11A shows a state in which the light L1 traveling inside the light guide plate 10 is transmitted through the side walls 12a of the radial ridges 12. FIG. 11B is a diagram showing a state in which the light L1 in FIG. 11A is diffusely reflected by the diffusive reflecting plate 6, passes through the light guide plate 10 again, and travels toward the dial plate 2. FIG.

  In this light guide plate 10, the radial ridges 12 are formed on the back surface 10 </ b> B of the light guide plate 10 instead of the radial grooves. Therefore, as shown in FIG. The incident angle of the light L1 can be reduced (can be made incident at an angle close to vertical), and as much light as possible is transmitted through the side wall 12a of the radial ridge 12 to the diffuse reflector 6 Can be directed. That is, since the light directly reflected by the side wall 12a of the radial ridge 12 can be reduced and the light diffusely reflected by the diffuse reflector 6 can be increased as shown in FIG. As much as possible, the dial 2 can be illuminated from behind with uniform light L1.

  Further, in this light guide plate 10, the amount of light transmission decreases as the distance from the light source 8 decreases. However, as the distance from the light source 8 increases so as to compensate for this, the density of the radial ridges 12 increases. The distribution of the illumination light quantity in the circumferential direction of the optical plate 10 can be made uniform.

  Further, in the instrument 1 using the light guide plate 10, the air layer K is secured between the light guide plate 10 and the diffuse reflector 6 because the radial ridges 12 are provided on the back surface 16 </ b> B of the light guide plate 10. Therefore, the diffuse reflection range of light at the diffuse reflector 6 can be expanded. This point will be described with reference to FIG. FIG. 12A is a schematic explanatory view showing the diffusion of light when an air layer is secured on the back surface of the light guide plate, and FIG. 12B is the light when no air layer is secured on the back surface of the light guide plate. It is a schematic explanatory drawing which shows spreading | diffusion.

  As shown in FIG. 12B, when an air layer is not secured between the light guide plate 10 and the diffuse reflector 6, the diffuse reflection range of light on the diffuse reflector 6 becomes narrow. Therefore, there is a tendency that the illumination range H <b> 2 for the dial plate by the light transmitted through the light guide plate 10 is narrowed. On the other hand, as shown in FIG. 12A, when the air layer K is secured between the light guide plate 10 and the diffuse reflector 6, the diffuse reflection range of light on the diffuse reflector 6 is widened. be able to. Therefore, the illumination range H1 with respect to the dial plate by the light transmitted through the light guide plate 10 can be widened, which can contribute to the improvement of luminance spots.

  Next, a configuration example for securing the air layer K on the back surface 10B side of the light guide plate 10 will be described with reference to FIGS. 13 (a) to 13 (c).

  In the example of FIG. 13A, a recess 25 is formed on the back surface 16B of the light guide plate 10, and the air layer K is secured between the back surface 16B of the light guide plate 10 and the front surface of the diffuse reflector 6 by the recess 25. ing. In this case, the radial ridges 12 on the back surface 16 </ b> B of the light guide plate 10 are formed on the inner bottom surface of the recess 25.

  In the example of FIG. 13B, a concave portion 25 is formed on the front surface of the diffuse reflector 6 constituted by a part of the wall of the casing 4, and the concave portion 25 allows the back surface 16 </ b> B of the light guide plate 10 and the diffuse reflector 6 to be formed. An air layer K is secured between the front surface. In this case, the radial ridges 12 on the back surface 16B of the light guide plate 10 are formed in a range where at least the recesses 25 are formed.

  In the example of FIGS. 13A and 13B, the concave portion 25 is formed on one of the back surface 16 </ b> B of the light guide plate 10 and the front surface of the diffuse reflector 6 facing each other. The air layer K may be secured by forming recesses on both the back surface 16B of the light source and the front surface of the diffuse reflector 6.

  In the example of FIG. 13C, the spacer 26 is sandwiched between the back surface 10 </ b> B of the light guide plate 10 and the front surface of the diffuse reflector 6, so that the back surface 10 </ b> B of the light guide plate 10 and the front surface of the diffuse reflector 6 are An air layer K is secured between them.

  As in the configuration examples shown in FIGS. 13A to 13C, the light guide plate 10 and the diffuse reflection plate 6 are provided with a recess 25, or the spacer 26 is sandwiched between the light guide plate 10 and the diffuse reflection plate 6. As a result, it is possible to secure an air layer K having a constant interval between the light guide plate 10 and the diffuse reflector 6. Then, the presence of the air layer K can widen the diffuse reflection range of the light at the diffuse reflection plate 6, thereby widening the illumination range for the dial 2 by the light transmitted through the light guide plate 10. Thus, it becomes possible to contribute to the improvement of luminance spots.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimensions, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

FIG. 14A to FIG. 14C are views showing variations in the cross-sectional shape of the arcuate ridges.
14A shows an arc-shaped ridge 11A having a quadrangular cross section formed on the front surface 16A of the light guide plate 10, and FIG. FIG. 14C shows an arc-shaped ridge 11 </ b> C having a trapezoidal cross section formed on the front surface 16 </ b> A of the light guide plate 10. The arc-shaped ridges 11 </ b> A to 11 </ b> C occupy most of the area of the front surface 16 </ b> A of the light guide plate 10.

FIGS. 15A to 15C are views showing variations in the cross-sectional shape of the radial ridges.
In the light guide plate 10 of the above embodiment, as shown in FIG. 15A, the case where the radial protrusions 12 having a triangular cross section are formed on the back surface 16B of the light guide plate 10 is shown. Thus, the radial ridge 12B having a trapezoidal cross section may be formed, or as shown in FIG. 15C, the radial ridge 12C having a semicircular cross section or a semielliptical cross section may be formed.

  In the above embodiment, the light guide plate 10 having the light incident end face 18 at one end in the circumferential direction is shown. However, the present invention can also be applied to a light guide plate having light incident end faces at both ends in the circumferential direction.

  In the above-described embodiment, the light guide plate 10 having a circular arc shape when viewed from the front side is described. However, the present invention can also be applied to a light guide body having a curved shape when viewed from the front side.

  Here, the features of the embodiments of the light guide plate and the meter according to the present invention described above are briefly summarized and listed in the following [1] to [6], respectively.

[1] A light source that is formed in a curved shape when viewed from the front, is disposed on the back surface of the dial (2) with the plate surface facing forward, and is incident from a light incident end surface (18) provided at an end of the curved shape. A light transmissive light guide plate (10) for guiding light from (8) so as to illuminate the dial (2) from the back;
Before connecting the illumination main body (16) having a light emission surface (16A) facing the back of the dial (2) in front, and the light incident end face (18) and the illumination main body (16). A light guiding part (17) for guiding the light incident on the writing light end face (18) to the illumination main part (16),
On the light emission surface (16A) of the illumination main body (16), a large number of curved ridges (11) extend along the curved shape and are spaced in a direction perpendicular to the extending direction. Formed,
The surface (17A) of the light guiding portion (17) in which the end surface (11t) on the light incident end surface (18) side of the curved ridge (11) smoothly continues as the same surface as the light emitting surface (16A). A light guide plate (10), which is located on the outer side of the light guide plate.

  [2] The light guiding portion (17) is curved toward the back surface (16B) side of the light guide plate (10) from the illumination main body portion (16) side toward the light incident end surface (18). The light guide plate (10) according to [1], which is characterized in that it is characterized in that

[3] The dial (2) is formed between the dial (2) on the front and the diffuse reflector (6) disposed on the back of the dial (2). ) And the diffuse reflector (6) through an air layer (K),
The curved ridges (11) extend along the circumferential direction of the arc shape and are spaced apart in the radial direction of the arc shape on the light emission surface (16A) of the illumination main body (16). A large number of arc-shaped ridges (11) formed, and radially along the radial direction of the arc shape on the back surface (16B) of the illumination main body (16) facing the diffuse reflector (6) The light guide plate (10) according to the above [2], wherein the light guide plate (10) has a large number of radial ridges (12) extending in the circumferential direction and spaced apart in the circumferential direction.

  [4] The interval at which the radial ridges (12) are formed is set so as to gradually decrease as the distance from the light incident end face (18) into which light from the light source (8) is incident is increased. The light guide plate (10) according to [3] above.

[5] The light guide plate (10) according to the above [3] or [4] includes the dial (2) and the diffuser between the dial (2) and the diffuse reflector (6), respectively. A meter (1) disposed between the reflector (6) and the air layer (K),
The air layer (K) on the back surface (16B) of the light guide plate (10) on at least one of the back surface (16B) of the light guide plate (10) and the front surface of the diffuse reflector (6) facing each other. A meter (1) characterized in that a recess (25) is provided for securing

[6] The light guide plate (10) according to the above [3] or [4] includes the dial (2) and the diffuse reflection between the dial (2) and the diffuse reflector (6), respectively. A meter (1) arranged between the plate (6) via an air layer (K),
The air layer (K) on the back surface (16B) of the light guide plate (10) is secured between the back surface (16B) of the light guide plate (10) and the front surface of the diffuse reflector (6) facing each other. An instrument (1), characterized in that a spacer (26) is sandwiched between them.

2 Dial plate 6 Diffuse reflection plate 8 Light source 10 Light guide plate 11 Arc-shaped ridge 11t End surface 12 Radial ridge 16 Illumination main portion 16A Light emission surface 16B Back surface 17 Light guide portion 17A Surface 18 Light incident end surface 25 Concave portion 26 Spacer K Air layer

Claims (6)

It is formed in a curved shape when viewed from the front, is arranged on the back surface of the dial with the plate surface facing the front, and the light from the light source incident from the light incident end surface provided at the end of the curved shape is A light-transmissive light guide plate that leads to illuminate from the back,
An illumination main body having a light-emitting surface facing the back of the dial in front, and connecting the light incident end face and the illumination main section to guide the light incident on the light incident end face to the illumination main section. A light guiding part,
A large number of curved ridges are formed on the light emitting surface of the illumination main body along the curved shape and spaced in a direction perpendicular to the extending direction,
The light guide plate, wherein an end face on the light incident end face side of the curved ridge is positioned outside a surface of the light guiding portion that smoothly continues as the same surface as the light emitting surface.   The light guide plate according to claim 1, wherein the light guiding portion is curved toward the back side of the light guide plate from the illumination main body side toward the light incident end surface. It is formed in a circular arc shape when viewed from the front, and between the dial on the front and the diffuse reflector disposed on the back of the dial, an air layer is interposed between the dial and the diffuse reflector, respectively. Arranged,
A large number of arc-shaped ridges extending along the circumferential direction of the arc shape and spaced in the radial direction of the arc shape on the light emitting surface of the illumination main body as the curved ridges. And a large number of radially extending along the radial direction of the arc shape and spaced apart in the circumferential direction of the arc shape on the back surface of the illumination main body facing the diffuse reflector The light guide plate according to claim 2, wherein the light guide plate has radial ridges.   4. The light guide plate according to claim 3, wherein an interval between the radial ridges is set so as to gradually decrease as the distance from a light incident end face on which light from the light source is incident. 5. The light guide plate according to claim 3 or 4, wherein the light guide plate is an instrument disposed between the dial plate and the diffusive reflection plate via an air layer between the dial plate and the diffusive reflection plate, respectively. ,
A measuring instrument, wherein a recess for securing the air layer on the back surface of the light guide plate is provided on at least one of the back surface of the light guide plate and the front surface of the diffuse reflection plate facing each other. The light guide plate according to claim 3 or 4, wherein the light guide plate is an instrument disposed between the dial plate and the diffuse reflection plate via an air layer between the dial plate and the diffuse reflection plate, respectively.
An instrument, wherein a spacer for securing the air layer on the back surface of the light guide plate is sandwiched between the back surface of the light guide plate and the front surface of the diffuse reflection plate facing each other.

Images