Collimation prism and illumination structure for window glass of vehicle

Abstract

The invention provides a collimating prism and an illumination structure for a window glass of a vehicle. The prism for collimation is used for illumination of glass for a vehicle and is provided with a light incident surface; a light emitting surface; the end surface is positioned on the opposite side of the light-in surface relative to the light-out surface; and a reflecting surface that reflects light incident from the light incident surface toward the light emergent surface, in a cross-section of the prism including the light incident surface, the reflecting surface, the light emergent surface, and the end surface in a contour, the contour of the reflecting surface includes at least one linear portion, and the linear portion includes at least one linear portion in a cross-section of the prism including the light incident surface, the reflecting surface, the light emergent surface, and the end surface in a cross-section of the prism. The light incident from a predetermined position of the light incident surface and reflected from a plurality of positions of the reflecting surface having different inclination angles with respect to the light emitting surface is emitted at the same emission angle on the light emitting surface. The illumination structure includes the prism, a light source, and a glass plate.

Description

TECHNICAL FIELD

[0001] The present application relates to a collimating prism used in illumination of a window glass or the like of a vehicle, and an illumination structure for a window glass of a vehicle using the same. BACKGROUND

[0002] In recent years, in vehicles such as automobiles, the number of models in which a roof is constituted by a glass is increasing. In the past, a glass roof had a problem of being easily affected by sunlight and external air temperature, but these problems were solved by improvement of heat insulation / heat resistance of the glass. By making the roof glass, an open interior space can be realized, and the comfort of an occupant can be improved.

[0003] In particular, in recent years, battery-mounted electric vehicles (BEVs) are becoming widespread, but most BEVs lay a battery on the ground, so the ground rises, and the gap between the roof and the head of an occupant becomes small, compared with conventional automobiles. Even in this case, as long as a glass roof is adopted, it is possible to avoid a sense of confinement and ensure the comfort of a passenger, so in the future, it is expected that glass roofs will further spread.

[0004] As a means for further improving the design of a glass roof and increasing added value, an illumination structure in which the roof itself emits light is attracting attention. At this time, if the glass itself becomes special, it is difficult to avoid an increase in cost, so a technology in which light emitted from another light source is guided to a general window glass for a glass roof via an optical prism to make the window glass emit light is being studied.

[0005] For example, in Japanese Patent Application Laid-Open No. 2023-520153 (hereinafter, Patent Document 1), a vehicle window glass is described, which has a window glass main assembly having an outer side surface facing the outside of a vehicle and an inner side surface facing the inside of the vehicle, the window glass main assembly having a light guide layer, and a light source configured to couple light with the light guide layer, the vehicle window glass being characterized in that an input coupling element that couples light emitted by the light source with the light guide layer is provided to the inner side surface of the window glass main assembly.

[0006] In Patent Document 1, it is described that in order to optimize the input coupling angle of light coupled with the light guide layer, the input coupling element has a wedge-shaped or trapezoidal cross section, and functions as an optical prism. However, a light source such as an LED, which is generally used, radiates light in multiple directions, so in a prism having a wedge-shaped (triangular) or trapezoidal cross section, it is not possible to make the light incident on the light guide layer (inner side glass) be parallel light having a constant incident angle.

[0007] As a window glass for an automobile, a laminated glass in which an inner glass and an outer glass are joined via an interlayer film is sometimes used. In order to cause the window glass to emit light using an external light source, it is preferable that light be guided to a position away from the light source by repeating reflection between the inner surface of the inner glass (the inner surface of the window glass) and the interface of the interlayer film and the inner glass. In this case, the optimum incident angle of light with respect to the window glass is limited to a narrow range, and therefore a prism for taking in light emitted from the external light source into the window glass preferably has the function of a collimating prism in which the incident angle of light to the window glass, that is, the exit angle of light from the prism, is constant.

[0008] On the other hand, in order to be suitable for industrial production in line with the production scale of automobiles, it is preferable that the assembly of the light source and the prism be easily performed. Also, in order to ensure the degree of freedom in design as a window glass, it is preferable that the size of the light source, the prism, and the like be suppressed as much as possible. SUMMARY

[0009] Therefore, an object of the present application is to provide an optical prism (light collimating prism) having a collimating function of causing at least a part of light incident from a light source to exit as parallel light, and which is easy to assemble with a window glass and a light source, and which can also cope with space saving, and a window glass illumination structure for a vehicle having the prism.

[0010] As a means for solving the above problem, the present application includes the following structure.

[0011] A first structure of the present application is a prism, which is a light collimating prism for illumination of a glass for a vehicle, in which the prism has a light incident surface, a light exit surface, and a reflection surface that reflects light incident from the light incident surface toward the light exit surface, in a cross section of the prism in which the light incident surface, the reflection surface, and the light exit surface are included in an outline, the outline of the reflection surface includes at least one straight portion, and light (light rays) that is incident from a prescribed position of the light incident surface and is reflected from a plurality of positions of the reflection surface that differ in inclination with respect to the light exit surface exits the light exit surface at the same exit angle.

[0012] According to the prism of the above structure, by collimating the exit angle of light exiting the exit surface, light can be caused to be incident to different positions of the glass for a vehicle in parallel.

[0013] Regarding a prism of a second structure, in the prism of the first structure described above, in a cross section of the prism in which the light incident surface, the reflection surface, and the light exit surface are included in an outline, the reflection surface has a shape of a broken line composed of a plurality of tangents of which the radius of curvature differs depending on the distance from the light exit surface.

[0014] According to the prism of the above structure, even if the position of the light source opposite to the light incident surface deviates from the ideal position, the function of the collimating prism that makes the emission angle of light emitted from the light emission surface uniform can be exerted.

[0015] Regarding the prism of the third structure, in the prism of the first structure or the second structure, the angle formed by the light incident surface and the light emission surface is greater than 90° (preferably 115° to 125°).

[0016] According to the prism of the above structure, the loss of light of the prism can be reduced, and the utilization efficiency of light can be improved.

[0017] Regarding the prism of the fourth structure, in the prism of any one of the first structure to the third structure, the prism has a configuration in which a light guide portion having the light incident surface, the light emission surface, and the reflection surface and a support plate portion having a first surface that is the same surface as the light emission surface and a flat second surface opposite to the first surface are alternately arranged in the length direction.

[0018] According to the prism of the above structure, by joining the flat second surface of the support plate portion to a substrate on which the light source (LED) is provided, the plurality of light sources can be accurately opposed to the light incident surface of the light guide portion at the same height position, and reduction in brightness caused by positional deviation of the light source from the prism can be prevented or suppressed.

[0019] Regarding the prism of the fifth structure, in the prism of any one of the first structure to the third structure, the light incident surface and the light emission surface have a semicircular profile with respect to the distal end of the light incident surface when viewed from above.

[0020] According to the prism of the above structure, a large range of glass can be illuminated with a small number of light sources.

[0021] The sixth structure is an illumination structure for a window glass of a vehicle, in which the illumination structure includes a window glass body having at least one glass sheet, a light source, and a prism of any one of the first structure to the fifth structure, the light source being arranged on the side of the light incident surface of the prism, and the light emission surface of the prism being bonded to the surface of the glass sheet via an adhesive layer.

[0022] According to the illumination structure of the above structure, light emitted from the light source can be effectively guided within the glass sheet of the window glass body.

[0023] Regarding the lighting structure of the seventh structure, in the lighting structure of the above-mentioned sixth structure, the window glass main body has a three-layer structure consisting of a first glass plate, a second glass plate and an intermediate film, and the intermediate film is arranged between the first glass plate and the second glass plate. The light (light ray) incident on the window glass main body from multiple positions of the light-emitting surface of the prism through the adhesive layer is totally reflected at the interface between the second glass plate and the intermediate film.

[0024] According to the lighting structure having the above configuration, the light emitted from the light source can be effectively guided within the second glass plate.

[0025] Regarding the lighting structure of the eighth configuration, in the lighting structure of the seventh configuration, the refractive index of the materials of the elements constituting the lighting structure satisfies the relationship of prism>adhesive>second glass plate>intermediate film.

[0026] According to the lighting structure having the above configuration, it is possible to contribute to improvement in light utilization efficiency, and to reduce the size of the prisms constituting the lighting structure, thereby improving the design of the illuminated glass.

[0027] Regarding the lighting structure of the ninth configuration, in any one of the lighting structures of the sixth to eighth configurations, the window glass main body is a roof glass.

[0028] According to the prism of the present invention, even if the position of the light source slightly deviates from the optimal position, a certain collimation function can be maintained, thereby simplifying the assembly work of the lighting structure while ensuring high luminous efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A This is a partial plan view (top view) of a prism according to one embodiment of the present invention.

[0030] Figure 1B It is along Figure 1A Cross-sectional view of the IB-IB line.

[0031] Figure 2 This is a cross-sectional view showing a state in which a prism is bonded to an inner glass to form a lighting structure according to an embodiment of the present invention.

[0032] Figure 3 It is a schematic cross-sectional view for explaining the optical design in the lighting structure of the prior art and the present invention.

[0033] Figure 4 This is a schematic diagram used to explain Snell's law.

[0034] Figure 5 1 is a diagram showing the results of an optical simulation in a conventional lighting structure having a prism having a rectangular cross section.

[0035] Figure 6A is a view showing the optical path of light in which the interface of the inner side glass becomes a total reflection condition in the simulation result shown in Figure 5 is a view showing the optical path of light in which the interface of the inner side glass becomes a total reflection condition in the simulation result shown in

[0036] Figure 6B is a view showing the result of optical simulation in the illumination configuration having a prism with a cross section of a wedge shape in the related art.

[0037] Figure 6C is a view showing the result of optical simulation in the illumination configuration having a collimating prism with a profile of a reflection surface in a cross section being a curve in the prototype of the present application.

[0038] Figure 7A is a view showing the optical path in the prism in the case where a light source is located at a prescribed position in the illumination configuration having a collimating prism with a reflection surface being a compound plane in one embodiment of the present application.

[0039] Figure 7B is a view showing the optical path in the prism in the case where a light source is deviated from a prescribed position in the illumination configuration having a collimating prism with a reflection surface being a compound plane in one embodiment of the present application.

[0040] Figure 7C is a view for explaining the angle between adjacent reflection surfaces in a collimating prism with a reflection surface being a compound plane.

[0041] Figure 8 is a view showing the result of optical simulation in the illumination configuration having a prism with a reflection surface being a compound plane in one embodiment of the present application.

[0042] Figure 9 is a perspective view showing a model of the illumination configuration used in the simulation of the light guide efficiency.

[0043] Figure 10 is a graph showing the change in the light guide efficiency caused by the position of a light source for the case where the prism of each mode is used.

[0044] Figure 11 is a graph showing the change in the light guide efficiency caused by the position of a light source for different wavelengths of light in the illumination configuration of one embodiment of the present application.

[0045] Figure 12A is a schematic cross-sectional view for explaining the case where the light incident surface of a prism is inclined with respect to the light exit surface in the illumination configuration of one embodiment of the present application.

[0046] Figure 12Bis a view showing a result of optical simulation in a lighting configuration having a prism with an inclined light-incident surface with respect to a light-emitting surface.

[0047] Figure 13A is a partial plan view showing a state in which a prism of a modification example of the embodiment of the present application is assembled with a light source.

[0048] Figure 13B is a sectional view along Figure 13A line XIIIB-XIIIB of FIG. 12B.

[0049] Figure 13C is a sectional view along Figure 13A line XIIIC-XIIIC of FIG. 12C.

[0050] Figure 14 is a schematic plan view showing a lighting configuration having a semicircular prism in one embodiment of the present application.

[0051] Figure 15 is a sectional view along Figure 14 line XV-XV of FIG. 15.

[0052] Figure 16 is a view showing a lighting state of a roof glass in a case where one LED light source is opposed to a rod-shaped prism.

[0053] Figure 17A is a view showing a lighting state of a roof glass in a case where three LED light sources are opposed to a rod-shaped prism.

[0054] Figure 17B is a view showing a lighting state of a roof glass in a case where three LED light sources are opposed to a semicircular prism.

[0055] Explanation of Reference Numerals

[0056] 1: prism; 1a: light-incident surface; 1b: light-emitting surface; 1c: reflecting surface; 1d: end surface; 1e: distal end with respect to the light-incident surface; 1f: first surface; 1g: second surface; 2: light source; 3: LED substrate; 4: housing; 6: relay substrate; 7: outer glass (first glass plate); 8: inner glass (second glass plate); 9: interlayer film; 10: roof glass; 11: adhesive layer; 12: wire harness; 100: lighting configuration; G: light guide portion; F: support plate portion. DETAILED DESCRIPTION

[0057] Figure 1A is a partial plan view of an optical prism 1 (hereinafter, sometimes referred to as prism 1) in one embodiment of the present application, and also shows a light source (LED) 2 opposed to the prism 1. Figure 1B is a sectional view along Figure 1ACross-sectional view along line IB-IB. In this example, the prism 1 is in the shape of an elongated plate and is surrounded by a light incident surface 1a, an end surface 1d (an end surface on the far side relative to the light incident surface), a light emitting surface 1b, and a reflecting surface 1c. The light incident surface 1a is incident on the light from the light source 2, the end surface 1d is located on the opposite side of the light incident surface 1a in the width direction of the prism 1, the light emitting surface 1b is in contact with the light incident surface 1a on one side in the length direction and with the end surface 1d on the other side, and the reflecting surface 1c is in contact with the light incident surface 1a on one side in the length direction and is located on the opposite side of the light emitting surface 1b in the thickness direction of the prism 1. Light incident from the light incident surface 1a is reflected by the reflecting surface 1c toward the light emitting surface 1b. In addition, the end surface 1d is not necessary. For example, the light emitting surface 1b may be in direct contact with the reflecting surface 1c to form an end (end edge).

[0058] Hereinafter, the vehicle window glass is described using the roof glass, but the invention is not limited thereto. As the vehicle window glass, in addition to the roof glass, there are also windshield glass, door glass, side window glass, corner window glass, rear window glass, etc. The light-emitting surface 1b of the prism 1a is arranged according to the roof glass (refer to Figure 2 ) is a flat plane or a slightly curved surface, but the reflecting surface 1c is formed in such a shape that light (light rays) incident from a predetermined position of the light incident surface 1a and reflected from a plurality of positions of the reflecting surface 1c with different inclination angles relative to the light emitting surface 1b can be emitted from the light emitting surface 1b at the same angle of incidence. In the prism 1 of the present invention, in the cross section ( Figure 1B ), the contour of the reflecting surface 1c includes at least one straight line portion (in the example shown in the figure, four straight line portions S1 to S4). In addition, the contour of the light incident surface 1a in the cross section may also be straight line.

[0059] In addition, regarding the inclination angle of the reflecting surface 1c relative to the light output surface 1b, it is preferred that the inclination angle gradually changes toward the direction close to the light output surface 1b after temporarily inclining away from the light input surface 1a side to the end surface 1d side.

[0060] Figure 2is a sectional view showing a state in which the optical prism 1, the light source (LED) 2 are assembled to the roof glass 10 in one embodiment of the present application. The roof glass 10 has a laminated glass configuration in which an outer glass 7 facing the outside of the vehicle cabin and an inner glass 8 facing the inside of the vehicle cabin are joined via an interlayer film 9, and the light exit surface lb of the prism 1 is joined to the surface 8a of the inner glass 8 via an adhesive layer 11. The present application is characterized in the shape of the prism 1, particularly the shape of the reflecting surface lc of the prism 1, and the prism 1, the light source 2, the adhesive layer 11, and the roof glass 10 constitute a main part of the roof glass illumination configuration 100 of the present application.

[0061] In Figure 2 , a cross section of the LED substrate 3 provided with the light source 2, the relay substrate 6 connected to the LED substrate 3 and connected to the wire harness 12 via the socket 6a, and the housing 4 for housing the LED substrate 3, the relay substrate 6, and the prism 1 and the light source 2 together and assembling to the roof glass 10 is also shown, but these structures can be appropriately changed depending on the shape of the prism 1 and the roof glass 10.

[0062] Figure 3 is a conceptual diagram for explaining the optical design of the roof glass illumination configuration 100 in the prior art and the present application. The light L emitted from the exit surface lb of the prism 1 is refracted at the interface Bl of the prism 1 and the adhesive layer 11, the interface B2 of the adhesive layer 11 and the inner glass 8, and is incident to the inner glass 8. Here, in order to make the roof glass 10 emit light with a large area, it is preferable that the light L incident to the inner glass 8 repeatedly reflects at the interface B3 of the inner glass 8 and the interlayer film 9 and the surface 8a of the inner glass, while being guided with as long a distance as possible. Therefore, it is necessary that the light L incident to the inner glass 8 from the prism 1 via the adhesive layer 11 totally reflects at the interface B3 of the inner glass 8 and the interlayer film 9. The condition for this can be calculated by Snell's law.

[0063] As Figure 4 shown, in the case where light is incident from a medium A having an absolute refractive index n A to a medium B having an absolute refractive index n B , when the incident angle based on the normal N of the interface is set to θ A , and the refractive angle is set to θ B , by Snell's law, it becomes sinθ A / sinθ B = n B / n A .

[0064] Therefore, the condition for producing refraction in the medium B is sinθ A x n A / n B = sinθB ≤sin90°, so the incident angle θ A The critical angle θ m By sinθ m =n B / n A To calculate, in θ A <θ m When light is incident from medium A to medium B, at θ A >θ m When , total reflection occurs at the interface between medium A and medium B.

[0065] Through the above relationship, Figure 3 In the illustrated structure, it is possible to determine the conditions under which light emitted from the optical prism 1 transmits through the adhesive layer, enters the inner glass 8, and undergoes total internal reflection at the interface B3 between the inner glass 8 and the intermediate film 9. As an example, for light with a wavelength of 520 nm (green light), when the refractive index of the optical prism 1 is set to 1.60, the refractive index of the adhesive layer is set to 1.54, the refractive index of the inner glass 8 is set to 1.52, and the refractive index of the intermediate film 9 is set to 1.48, the angle of incidence θ1 from the optical prism 1 to the interface B1 between the optical prism 1 and the adhesive layer 11 should satisfy the condition of 68.1° < θ1 < 72.0°.

[0066] As described above, the preferred angle range is limited, so the optical design of the prism 1 is important in making the roof glass 10 emit light. Ideally, the light (light ray) L emitted from different positions of the exit surface 1b of the prism 1 is preferably emitted at the same exit angle (refractive angle when a medium is present on it) θ2. In this case, the light incident from the light source 2 and directly toward the exit surface has different exit angles in the radiation direction, so it is preferable to adjust the shape of the reflecting surface 1c of the prism 1 so that the light L reflected at different positions of the reflecting surface 1c is incident on the light exit surface 1b at the same incident angle θ1 and is emitted at the same exit angle (refractive angle) θ2.

[0067] Figure 5 This is a schematic cross-sectional view showing an illumination structure 100 in which a prism 1 having a rectangular cross section is installed. However, since the outer glass hardly participates in illumination, the adhesive layer is relatively thin and therefore is omitted from the illustration (hereinafter, Figure 6A-C 、 Figure 8 The dotted line in the figure represents the optical path of light obtained by optical simulation.

[0068] Figure 6A-C 1 is a schematic cross-sectional view showing an illumination structure 100 incorporating prisms 1 of different shapes. As a result of optical simulation, only the optical path of light that satisfies the above-described total reflection condition is indicated by a dotted line. Figure 6A Shows the installation Figure 5The cross section of the rectangular prism 1 is shown in FIG. 1. The illumination structure 100 is shown in FIG. 2. The illumination structure 100 is shown in FIG. 3. Figure 5 In contrast to the illumination structure shown in FIG. 2, in the rectangular prism 1, the light from the prism 1 is not substantially collimated, and the light that escapes through the interlayer film 9 increases. Figure 6A

[0069] Figure 6B FIG. 4 is a schematic cross-sectional view showing an illumination structure 100 in which a prism 1 having a cross section in the shape of a wedge is installed, and corresponds to the illumination structure described in Patent Document 1. In this shape, the light emitted from the light source 2 cannot be collimated at different positions of the reflecting surface 1c of the prism 1, and thus only a portion of the light reflected from the reflecting surface 1c of the prism and incident on the inner glass 8 undergoes total reflection at the interface 9a with the interlayer film 9.

[0070] Figure 6C FIG. 5 is a schematic cross-sectional view showing an illumination structure 100 in which a collimating prism 1 designed as a prototype of the present application is installed. In this example, the reflecting surface 1c of the prism 1 is formed as a curved surface, and a curved profile is shown in the cross section. The radius of curvature of the profile differs depending on the distance from the light-incident surface 1a opposite to the light source. By making the reflecting surface 1c curved, the inclination of the reflecting surface 1c can be varied depending on the emission direction of the light from the light source 2, and the emission directions of the light reflected from a plurality of positions on the reflecting surface 1c can be collimated to be substantially the same direction. In the example shown in the figure, the profile represents a curve in which the radius of curvature increases as the distance from the light-emitting surface increases, but a different curve shape can be employed depending on the optical design of the illumination structure.

[0071] In the illumination structure shown in FIG. 2, the light emitted from the light source 2 and incident on the prism 1 is collimated in the appropriate direction by the reflecting surface 1c, and thus the amount of light that undergoes total reflection at the interface B3 between the inner glass 8 and the interlayer film 9 can be increased, and guided to a position away from the light source in the inner glass 8. In this illumination structure 100, in order for the prism 1 to function as a collimator, the light source 2 needs to be accurately positioned at a position that corresponds to the optical design, and if the position of the light source 2 is shifted, the prism 1 cannot function as an appropriate collimator. Figure 6C In order to solve the above problems, research has been continued, and as a result, it has been found that the reflecting surface 1c of the prism 1 shaped to have a collimating function can maintain the collimating function of the prism 1 even if the position of the light source 2 is shifted to some extent, by being structured to include at least one straight portion in the profile of the cross section including the light-incident surface 1a, the light-emitting surface 1b, and the reflecting surface 1c, thereby maintaining the effect as the illumination structure 100.

[0072] Figure 3

[0073] ​​​The profile of the reflecting surface 1c in the above cross section can be composed of a curved portion and a straight portion, but can also show a profile in a broken line shape composed of a plurality of straight portions having different angles with respect to the light incident surface 1a. In this case, the profile of the reflecting surface 1c is preferably composed of three or more straight portions, more preferably five or more straight portions, and can also be composed of eight or more straight portions. The shape of the broken line is preferably a shape approximating to a curve optimal for the collimation function. For example, the shape of the broken line can also be composed of three or more tangent lines which are tangent to a curve (for example, a curve in which the radius of curvature increases as the distance from the light incident surface 1a increases) having different radii of curvature depending on the distance from the light incident surface 1a at different positions. The upper limit of the number of straight portions is not particularly limited, but from the viewpoint of the function of compensating for a positional shift of the light source and the processability, it can be 12 or less.

[0074] In the above description, the shape of the prism 1 has been described by the profile of the cross section, but in the case where the prism 1 assumes an elongated shape extending long in a straight line direction when viewed from above the light exit surface 1b, the reflecting surface 1c becomes a shape including a plane, for example, a shape composed of a plurality of planes (compound plane) having different angles with respect to the light incident surface 1a. On the other hand, in the case where the prism 1 is curved when viewed from above, the portion in a straight line shape in the cross section also becomes a curved surface. For example, in the case where the prism 1 assumes a circular arc shape when viewed from above, the reflecting surface 1c includes a conical surface.

[0075] Figure 7A is a schematic cross-sectional view showing the collimation function of the prism 1 of the present application, and shows a case where the reflecting surface 1c of the prism is composed of a compound plane. The planes P1, P2, P3, P4 constitute straight line portions S1 to S4 having different angles with respect to the light incident surface 1a in the profile of the cross section of the prism 1, and the profile of the reflecting surface 1c is formed in a broken line shape. The light L1 to L4 incident in a prescribed direction from the light source 2 opposite to the prism 1 is reflected in the same direction by the plurality of planes P1 to P4. Figure 7B is a schematic cross-sectional view showing the collimation function of the prism 1 of the present application, and shows a case where the reflecting surface 1c of the prism is composed of a compound plane. The planes P1, P2, P3, P4 constitute straight line portions S1 to S4 having different angles with respect to the light incident surface 1a in the profile of the cross section of the prism 1, and the profile of the reflecting surface 1c is formed in a broken line shape. The light L1 to L4 incident in a prescribed direction from the light source 2 opposite to the prism 1 is reflected in the same direction by the plurality of planes P1 to P4. Figure 7A In the structure shown in Figure 7A In the structure shown in Figure 7Bis designed for illustration and does not reflect actual size ratios.

[0076] Figure 7C is a view for further explaining the shape of the reflecting surface 1c of the prism 1. The reflecting surface 1c of the prism 1 has a shape that gradually approaches the light exit surface 1b after temporarily moving away from the light exit surface 1b. For example, in a case where the reflecting surface 1c is an n (n is an integer of 3 or more, and is 4 in the drawing) number of composite bodies of n planes P1 to Pn, and the profile of the reflecting surface 1c in the cross section of the prism 1 is constituted by n straight line portions S1 to Sn, in a case where the straight line portion adjacent to the light entrance portion 1a is set as S1, an arbitrary straight line portion is set as Sk (k is an integer of 1 to n-1, and is 3 in the drawing), and the straight line portion adjacent to Sk (k is an integer of 1 to n-1, and is 3 in the drawing) on the distal side with respect to the light entrance surface 1a is set as Sk+1, the angle a formed by S1 and the light exit surface 1b is preferably greater than 0°. In addition, the angle βk formed by Sk and Sk+1 is preferably less than 180°. In addition, a is preferably 10° to 30°, and βk is preferably 160° to 180°, respectively and independently. In addition, the angle conditions described here are conditions related to the angle measured in the cross section perpendicular to the length direction, for example, in a case where the prism is a long and plate-like shape, in the cross section having the shortest length of the profile. Therefore, the above-mentioned angle conditions can also be referred to as angle conditions between adjacent planes. In addition, from the viewpoint of thickness, the prism 1 can also be a prism in which the thickness is the thickest between the light entrance surface 1a and the end surface (end portion) of the prism opposite to the light entrance surface. In addition, the position of the prism 1 where the thickness is the thickest is preferably a position where Sk and Sk+1 are in contact, for example, a position where S1 and S2 are in contact.

[0077] Figure 8 is a schematic cross-sectional view showing the lighting configuration 100 in which the prism 1 in which the reflecting surface 1c is constituted by 5 composite planes is installed. The optical simulation was also performed for this configuration, and it was confirmed that a certain collimation function was obtained in each of the surfaces constituting the reflecting surface 1c.

[0078] The optical simulation was performed for the lighting configuration shown in Figure 6A , Figure 6B , Figure 6C the lighting configuration 100 shown in Figure 8 , and the lighting configuration 100 in which the prism 1 in which the reflecting surface is constituted by 10 composite planes is additionally installed (not shown), and the light guide efficiency corresponding to the difference in the shape of the prism 1 was compared. Figure 9is a perspective view showing the structure of a model used in the simulation (for ease of illustration, the surface 8a of the inner side glass 8 is taken as the upper surface). The actual size of the model is made of a rod-shaped prism 1 of a bonding cross-sectional shape different according to each illumination configuration, with a roof glass 10 of a square of 300 mm on one side. The refractive index of the prism 1 is set to 1.597 (refractive index for green light of wavelength 520 nm, the same hereinafter), the maximum thickness is 3.0 mm, the refractive index of the adhesive layer (not shown) is 1.540, the thickness is 0.05 mm, the refractive index of the inner side glass 8 and the outer side glass 7 is 1.519 each, the thickness is 2.0 mm, the refractive index of the interlayer film 9 is 1.482, and the ratio of the total light beam at a position 30 mm away from the end surface of the prism opposite to the light entrance surface (dotted line portion) to the light beam emitted from the light source 2 is evaluated. At this time, the case where the light source 2 is deviated upward and downward by 0.25 mm and 0.50 mm from the prescribed position where the light guide efficiency is the largest is also evaluated. The results are shown in Table 1 and Figure 10 Table 2. As the wavelength of light, 520 nm of green light is used. The deviation of the light source 2 in the upward direction is taken as a positive value, and the deviation in the downward direction is taken as a negative value.

[0079]

Table 1

[0080]

[0081] From Table 1 and Figure 10 it can be seen that, compared with the illumination configuration using a prism of which the cross section is rectangular and the prism 1 having a wedge-shaped cross section described in Patent Document 1, in the case where the prism 1 having a collimating function with a reflection surface being a curved surface or a compound plane is used, a higher light guide efficiency of two times or more is obtained. In addition, in the case where the prism 1 having a reflection surface 1c composed of a compound plane according to the present application is used, compared with the case where the prism 1 having a curved reflection surface as a prototype of the present application is used, the maximum value of the light guide efficiency is slightly reduced, but the reduction of the light guide efficiency in the case where the position of the light source 2 is deviated can be suppressed.

[0082] The refractive index of each component differs depending on the wavelength of the incident light, and therefore, for the case where green light (wavelength 520 nm), blue light (wavelength 470 nm), and red light (wavelength 640 nm) are incident to the prism 1, simulation was performed regarding the light guide efficiency. In Figure 11The results are shown in . The reflective surface 1c is a 10-face composite. In the case of red light, the light conductivity is lower than that of green light and blue light, and the decrease in light conductivity increases with the positional shift of the light source 2. This is considered to be because the difference in refractive index between the inner glass 8 and the intermediate film 9 is smaller for light with a long wavelength. However, in conventional multi-color LEDs, for example, the ratio of RGB light beams is approximately 45:100:15, so the influence of the lower light conductivity of red light is relatively small, and it is believed that the lighting structure of the present invention does not have any practical problems when performing color displays.

[0083] exist Figure 7A-C 、 Figure 8 In the model shown, the light incident surface 1a of the prism 1, which is opposite to the light source 2, is perpendicular to the light exit surface 1b of the prism 1. However, the appropriate angle of the light incident surface 1a relative to the light exit surface 1b has been studied, and it has been found that the angle between the light incident surface 1a and the light exit surface 1b is preferably greater than 90°. The light (light ray) emitted from the light source 2, which is radiated upward, is directly emitted from the light exit surface 1b after entering the prism 1. Therefore, Figure 8 In the model shown, only this part is totally reflected at the interface 9a between the inner glass 8 and the intermediate film 9. In order to increase the number of light beams collimated to an appropriate exit angle among the light emitted from the prism 1, as shown in FIG. Figure 12A As shown, the light incident surface 1a is preferably tilted to guide as many light beams as possible to the reflecting surface 1c. The angle between the light incident surface 1a and the light emitting surface 1b is preferably 115° to 125°.

[0084] Regarding the prism 1 in which the reflecting surface 1c is composed of a composite plane, the light guide rate relative to the tilt angle when the incident surface 1a is tilted is as follows: Figure 12B Optical simulations were performed as shown.

[0085] When the vertical plane relative to the light-emitting surface 1b is set as the reference plane R, the inclination angle of the light-incident surface 1a relative to the reference plane R is It is preferably about 25° to 35°, more preferably 28° to 33°, and even more preferably around 30°. It becomes the angle formed by the above-mentioned light incident surface 1a and the light emitting surface 1b.

[0086] In the lighting structure 100 of the present invention, the refractive indices of the materials comprising the various elements of the lighting structure 100 preferably satisfy the relationship: prism 1 > adhesive 11 > inner glass (second glass plate) 8 > interlayer film 9. Specifically, the refractive index of the adhesive 11 is preferably lower than that of the prism 1, the refractive index of the inner glass 8 is preferably lower than that of the adhesive 11, and the refractive index of the interlayer film 9 is preferably lower than that of the inner glass 8. This improves light utilization efficiency and contributes to miniaturization of the prism.

[0087] Therefore, the material of the prism 1 and the adhesive 11 is appropriately selected according to the material of the roof glass 10 that emits light.

[0088] The first glass sheet 11 and the second glass sheet 12 that constitute the roof glass 10 can be inorganic glass or organic glass. As the inorganic glass, for example, soda-lime glass, alumino-silicate glass, borosilicate glass, non-alkali glass, quartz glass, or the like can be used.

[0089] As the interlayer film 9, for example, a thermoplastic resin can be used, and as the thermoplastic resin, polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), or the like can be used.

[0090] A pattern for diffuse reflection can also be provided in the roof glass 10. The pattern for diffuse reflection can be configured in layers, and is also referred to as a scattering layer. The shape of the pattern is not particularly limited, but for example, is circular, and a plurality of patterns can be provided at a prescribed interval. The pattern for diffuse reflection can be provided in any one of the outer glass 7 (first glass sheet 11), the inner glass 8 (second glass sheet 12), the interlayer film, or a different member from these. The method of forming the pattern for diffuse reflection can be arbitrary, and for example, can be roughening the surface of the glass sheet, printing a scattering paint on the surface of the glass or the surface of the interlayer film, or enclosing a sheet-shaped member on which a scattering paint is printed inside the interlayer film.

[0091] For the above reasons, the prism 1 is preferably made of a material having a higher refractive index than the inner glass. For example, polycarbonate or styrene methyl methacrylate copolymer can be used.

[0092] The adhesive layer 11 is commercially available as an optical clear resin, and therefore, a material having an appropriate refractive index can be used.

[0093] As an example of the combination, in the case where the roof glass 10 includes polyvinyl butyral as the interlayer film 9 and soda-lime glass as the outer glass 7 and the inner glass 8, the prism 1 can also be made of polycarbonate. In this case, the adhesive layer 11 can use an optical clear resin having a refractive index smaller than that of polycarbonate and larger than that of soda-lime glass. The same applies to the case where the roof glass 10 includes only one glass sheet (for example, soda-lime glass).

[0094] The inner glass and the outer glass can each have a thickness of about 1.0 mm to 6.0 mm, and the interlayer film 13 can have a thickness of about 0.1 mm to 1.2 mm.

[0095] In the case where the roof glass 10 includes only one glass sheet (for example, soda-lime glass), the prism 1 can be made of polycarbonate, and the adhesive layer 11 can use an optical clear resin having a refractive index smaller than that of polycarbonate and larger than that of soda-lime glass. Figure 9In the illustrated lighting structure 100, a rod-shaped (or long, plate-shaped) prism 1 is bonded to the surface 8a of the inner glass near the edge of the roof glass 10. When the prism 1 is attached to the flat roof glass 10, the prism 1 may extend in a straight line, but may also have a slightly curved light-emitting surface 1b depending on the shape of the roof glass 10. Figure 9 The model shown is for simulation purposes; the lighting structure 100 of the present invention can also be applied to large-area roof glass, such as that occupying a large portion of a car's roof. The dimensions of the prism 1 are not particularly limited; however, the width of the light-emitting surface 1b can be approximately 10 mm to 30 mm, and the maximum thickness can be approximately 2 mm to 4 mm. The length of the prism 1 can be, for example, approximately 50 mm to 1000 mm. When LEDs are used as light sources 2 and are positioned opposite the rod-shaped prism 1, it is sufficient to arrange the LEDs at intervals of approximately 1.5 mm to 50 mm, a number that matches the length of the prism 1.

[0096] Figure 13A This is a top view showing a state in which a light source (LED) 2 and an LED substrate are assembled to a prism 1 of a modified example of the above-described embodiment, in one embodiment of the present invention. Figure 13B Shown with Figure 13A The cross-sectional view after cutting along the XIIIB-XIIIB line, Figure 13C The cross-sectional view taken along line XIIIC-XIIIC is shown. In this example, the long plate-shaped prism 1 has a shape in which the light guide portion G and the support plate portion (plate-shaped support portion) F are alternately arranged in the longitudinal direction. Figure 13C As shown, the light guide portion G has a light incident surface 1a, an end surface 1d, a light exit surface 1b and a reflection surface 1c, and the limiting conditions related to its cross-sectional structure are the same as those of the prism 1 described above. On the other hand, regarding the support plate portion F, as shown Figure 13B As shown, a support plate portion F having a first surface 1f that is flush with the light-emitting surface 1b of the light guide portion G and a flat second surface 1g opposite to the first surface 1f is arranged adjacent to the light guide portion G along the longitudinal direction of the prism 1. Preferably, a plurality of light guide portions G and a plurality of support plate portions F are alternately arranged along the longitudinal direction of the prism.

[0097] The light guide portion G is integrally formed with the support plate portion F, and the thickness of the thickest portion of the light guide portion G is equal to or less than the thickness of the support plate portion F. That is, in the illustrated example, the prism 1 is formed such that the light guide portions G are formed at predetermined intervals on a long, uniformly thick plate. By joining the flat second surface of the support plate portion G to the LED substrate 3, the height position of the light source disposed on the LED substrate 3 can be accurately controlled.

[0098] right Figure 13A-CThe illustrated shape is described, the light guide portion G is in plan view, a hexagonal shape in which a rectangle is joined to the top side of a trapezoid, in the trapezoidal portion, the size viewed in the length direction of the prism 1 is enlarged in a manner expanding from the size Dl on the top side near the light source 2 to the size D2 on the end surface Id side away from the light source 2. Therefore, the light radiated from the light source 2 can be effectively utilized. Correspondingly, the support plate portion F sandwiched by the two light guide portions G is in plan view, a hexagonal shape in which a rectangle is joined to the bottom side of a trapezoid. With respect to the width of the prism 1, the width Wl of the light guide portion G is smaller than the width W2 of the support plate portion F. In addition, both ends in the length direction of the prism 1 can also adopt a shape in which the above-described light guide portion G or support plate portion F is cut off.

[0099] In addition, Figure 13A-C An example of an embodiment of the prism 1 including the light guide portion G and the support plate portion F is shown in FIG. 1, various modifications can be made depending on the necessity of design of the prism installation site or the necessity of prism molding, etc. For example, Figure 13B The support plate portion F is shown as having a structure in which the first face If and the second face Ig are parallel to each other, but the second face Ig can also be inclined with respect to the first face. In addition, the shape of the boundary between the light guide portion G and the support plate portion F can also be different from Figure 13A the shape shown by the broken line in FIG. 1.

[0100] In addition, the prism can also have a shape other than a rod shape. In order to improve the degree of freedom in the design of the interior of a vehicle, the prism constituting the illumination structure 100 is preferably further miniaturized, and in order to save energy, it is preferable to effectively perform illumination with as few light sources 2 as possible. From these viewpoints, research was conducted on the design of the illumination structure 100, and as a result, it was found that if a prism having a profile in plan view that is substantially semicircular (more accurately, substantially semicircular ring-shaped or fan-shaped) is used, effective illumination can be performed with fewer light sources 2.

[0101] Figure 14 is a plan view showing a state in which this prism 1 is installed to the inner side glass 8, Figure 15 is a cross-sectional view along the XV-XV line of Figure 14 In this prism 1, the profile of the reflecting face 1c (light exit face 51b) in plan view becomes a shape in which two circular arcs are connected by a straight line, the inner circular arc forms the profile of the light entrance face la, and the outer circular arc forms the profile of the distal end le with respect to the light entrance face la. In this prism, the cross-sectional structure can also be the same as in the above-described embodiment. In Figure 14 , Figure 15 In the example of FIG. 2, the reflecting face 1c exhibits a profile in the shape of a broken line composed of five faces P1 to P5 having different angles with respect to the light entrance face la. However, in this case, the reflecting face is not a complex plane, but a complex body of curved surfaces each forming a part of a conical surface having a different apex angle. InFigure 15 In the example of FIG. 1, the light-incident surface la of the prism 1 is perpendicular to the light-emitting surface lb, and thus the prism 1 has a shape that forms a portion of a cylinder, but the light-incident surface la can be inclined with respect to the perpendicular surface, and the prism 1 can have a curved surface shape that forms a portion of a conical surface. If the prism 1 having the above-described shape is used, a wide range of the glass can be illuminated with a small number of light sources 2.

[0102] The above describes the main structures of the prism 1 and the illumination structure 100 according to the present application, but these structures can be appropriately added or changed.

[0103] For example, in the above description, the case where the roof glass 10 has a three-layer structure of the outer glass 7, the inner glass 8, and the interlayer film 9 is described, but the interlayer film 9 can have a two-layer structure, and an optical pattern that improves the visual confirmation of reflected light can be provided in one layer. The interlayer film 9 can further include other layers such as an electrochromic layer (not shown). In addition, the roof glass 10 can not be a laminated glass structure, but can be configured to include only one glass sheet (for example, for convenience, the inner glass 8 is included).

[0104] The prism 1 is bonded to the vicinity of the edge of the roof glass 10, but for example, with respect to the roof glass 10 having a substantially rectangular profile, the prism 1 can be disposed in the vicinity of one side selected from the four sides, can be disposed in the vicinity of two opposite or adjacent sides, or can be disposed in the vicinity of three sides or all four sides.

[0105] With respect to the structure of the illumination structure 100 shown in FIGS. 1 to 3, the profile of the distal end surface le of the prism 1 with respect to the light-incident surface la is described as a circular arc, but the profile can form a portion of an ellipse. Figure 14 Figure 15 As the light source 2, a full-color LED or a white LED can be used. In the above description, a plurality of LEDs are disposed along the light-incident surface la of the prism 1, but a long LED can be used as the light source 2, and depending on the situation, a light guide body such as a side-emitting optical fiber can be disposed along the light-incident surface la of the prism 1, and a member that emits light into the light guide body from a laser light source can be used as the light source 2.

[0106] [Example]

[0107] [Example 1]

[0108] [Example 1]

[0109] As a simulated roof glass 10, a laminated glass obtained by sandwiching an interlayer film with two pieces of 500 mm x 200 mm sodium calcium glass having a thickness of 2 mm was prepared. A circular scattering pattern having a diameter of 7 mm was provided as a scattering layer at an interval of 18 mm in the interlayer film 11. An illumination unit composed of the prism 1 and the light source 2 was disposed on the short side of the glass, and the light source 2 was disposed in the vicinity of the light-incident surface la of the prism 1.​Figure 2 The structure shown was assembled. As the prism 1, a rod-shaped prism having a complex plane of a reflection surface of 6 faces (maximum thickness 3 mm, width of light exit surface 20 mm, length 100 mm) was formed by injection molding. The light exit surface lb of the prism 1 was bonded to the glass surface by an optically transparent resin. One full-color LED was disposed as the light source 2 in opposition to the light entrance surface la of the prism 1, and illumination was performed, and the results were the same as those of the optical simulation shown in Figure 16 The results of the optical simulation shown were the same, and it was confirmed that the green light and the blue light were emitted from the entire surface.

[0110] [Example 2]

[0111] In order to verify the effect of the illumination structure 100 provided with the prism 1 having a semicircular profile, two pieces of laminated glass having an area of 300 mm x 300 mm were prepared. The laminated structure was the same as in Example 1, but a circular pattern having a diameter of 7 mm was provided at an interval of 18 mm in the scattering layer of the interlayer film. A rod-shaped prism having a length of 150 mm (the cross-sectional shape was the same as in Example 1) was bonded by an optically transparent resin to one side of the laminated glass, and three full-color LEDs were disposed in opposition at an interval of 50 mm. A prism having a radius of 10 mm for the light entrance surface la and a radius of 30 mm for the distal end le of the light entrance surface, a maximum thickness of 3 mm, and a reflection surface composed of 5 faces was bonded by an optically transparent resin to the other side, and three full-color LEDs were disposed in opposition to the light entrance surface. The raw materials of the respective elements were the same as in Example 1. In the case where a rod-shaped prism 1 shorter than the side of the glass was used, as shown in Figure 17A dead angles were generated in the illumination portion, and in contrast, in the case where a semicircular prism 1 was used, as shown in Figure 17B the entire surface could be illuminated by three LEDs.

Claims

1. A prism which is a light collimating prism for illumination of a vehicle glass, wherein the prism has a light incident surface, a light exit surface, and a reflecting surface which reflects light incident from the light incident surface toward the light exit surface, in a cross section of the prism in which the light incident surface, the reflecting surface, and the light exit surface are included in a profile, the profile of the reflecting surface includes at least one straight line portion, and light incident from a prescribed position of the light incident surface and reflected from a plurality of positions of the reflecting surface which differ in inclination with respect to the light exit surface is emitted at the same exit angle on the light exit surface.

2. The prism according to claim 1, wherein in the cross section of the prism in which the light incident surface, the reflecting surface, and the light exit surface are included in a profile, the reflecting surface has a shape of a broken line, and the broken line is composed of a plurality of tangents which are tangent to a curve in which a radius of curvature differs depending on a distance from the light exit surface at different positions.

3. The prism according to claim 2, wherein an angle formed by the light incident surface and the light exit surface is greater than 90°.

4. The prism according to claim 1, wherein the prism has a configuration in which a light guide portion having the light incident surface, the light exit surface, and the reflecting surface and a support plate portion having a first surface which is the same surface as the light exit surface and a second surface which is a flat surface opposite the first surface are alternately arranged along a length direction.

5. The prism according to claim 1, wherein the light incident surface and the light exit surface have a profile of a semicircle with respect to a distal end of the light incident surface when viewed from above.

6. An illumination configuration which is a window glass illumination configuration for a vehicle, wherein the illumination configuration includes: a window glass main body having at least one glass sheet; a light source; and a prism according to any one of claims 1 to 5, the light source is arranged on a side of the light incident surface of the prism, and the light exit surface of the prism is bonded to a surface of the glass sheet via an adhesive layer.

7. The illumination configuration according to claim 6, wherein the window glass main body has a three-layer configuration composed of a first glass sheet, a second glass sheet, and an interlayer film which is arranged between the first glass sheet and the second glass sheet, and light incident from a plurality of positions of the light exit surface of the prism via the adhesive layer to the window glass main body is totally reflected at an interface between the second glass sheet and the interlayer film.

8. The illumination configuration according to claim 7, wherein a refractive index of a raw material of each element constituting the illumination configuration satisfies a relationship of prism > adhesive > second glass sheet > interlayer film.

9. The illumination configuration according to claim 6, wherein the window glass main body is a roof glass. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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