Display device and light guiding panel

A display device includes a light guiding panel 2 having an incoming surface 2a formed on one of side surfaces, a plurality of light sources (3-1 to 3-4) respectively corresponding to a plurality of patterns that can be displayed, and a controller 6 for controlling on and off of the plurality of light sources. The light guiding panel 2 has a first reflective surface (2d, 2e) formed on the other side surface of the light guiding panel 2, the first reflective surface reflecting light emitted from a first light source and entering the light guiding panel 2 through the incoming surface 2a, and changing the propagation direction of the light, and a plurality of prisms 11 which is formed on one surface 2b of the light guiding panel, is oriented toward light emitted from a light source corresponding to the pattern, entering the light guiding panel 2 through the incoming surface 2a, and directed to the pattern, and reflects the light so that the light is emitted through the other surface 2c of the light guiding panel.

TECHNICAL FIELD

The present invention relates to a display device capable of switching a displayed pattern, and a light guiding panel used in such a display device.

BACKGROUND ART

Conventionally, a display device has been proposed in which prisms are arrayed on one surface of a light guiding panel according to multiple patterns to be displayed, and a pattern to be displayed is dynamically switched by switching a light source to be turned on which is one of a plurality of light sources arranged to surround the light guiding panel. However, there may be a case in which light sources can be arranged only at a position along one side surface of the light guiding panel depending on a space in which the display device is disposed or the structure of a device in which the display device is incorporated. In view of this, a technique for dynamically switching a pattern to be displayed by switching a light source to be turned on in a plurality of light sources arranged along one side surface of a light guiding panel has been proposed (see, for example, Patent Document 1).

For example, the display device disclosed in Patent Document 1 includes a light guiding panel capable of displaying a plurality of patterns, a plurality of light sources arranged in line along one side of the sidewall of the light guiding panel, and a controller for controlling on and off of the plurality of light sources according to turn-on sequence information. The light guiding panel has a plurality of prisms that is arrayed on one surface of the light guiding panel for each pattern along the pattern, and reflects visible light which is emitted from a light source included in the plurality of light sources and corresponding to the pattern and which enters the light guiding panel through an incoming surface of the light guiding panel toward the other surface of the light guiding panel.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

In the display device disclosed in Patent Document 1, the prisms in each pattern are arrayed to face the incoming surface of the light guiding panel. Therefore, light emitted from the light source corresponding to the pattern to be displayed may also be reflected by the prisms arrayed in another pattern not corresponding to the light source, and directed toward a viewer, resulting in a case that a portion of another pattern not corresponding to the light source to be turned on may be visible to the viewer.

In view of this, an object of the present invention is to provide a display device capable of reducing the visibility of a pattern other than a pattern corresponding to a light source that emits light in a plurality of patterns, even when the light source can be arranged only along one side surface of the light guiding panel.

Means for Solving the Problem

As one aspect of the present invention, a display device is provided. The display device includes: a light guiding panel that is formed of a transparent member, is capable of displaying a plurality of patterns, and has an incoming surface formed on one of side surfaces; a plurality of light sources which is arranged to face the incoming surface and which corresponds to the plurality of patterns, respectively; and a controller configured to control on and off of the plurality of light sources. The light guiding panel has a first reflective surface formed on at least one of the other side surfaces of the light guiding panel, the first reflective surface reflecting light emitted from a first light source which is included in the plurality of light sources and entering the light guiding panel through the incoming surface, and changing a propagation direction of the light, and a plurality of prisms which is formed on one surface of the light guiding panel for each of the plurality of patterns, is arrayed along the pattern, is oriented toward light emitted from a light source which is included in the plurality of light sources and which corresponds to the pattern, entering the light guiding panel through the incoming surface, and directed to the pattern, and reflects the light so that the light is emitted through the other surface of the light guiding panel.

In this display device, it is preferable that the light guiding panel further has a second reflective surface formed on another side surface of the light guiding panel different from the first reflective surface, the second reflective surface further reflecting light emitted from the first light source and reflected by the first reflective surface, and directing the light toward a pattern included in the plurality of patterns and corresponding to the first light source.

Further, in this display device, it is preferable that the first reflective surface of the light guiding panel reflects light which is emitted from a second light source included in the plurality of light sources and enters the light guiding panel through the incoming surface, and directs the light toward a pattern included in the plurality of patterns and corresponding to the second light source.

Furthermore, in this display device, it is preferable that the first reflective surface of the light guiding panel is stepped along a direction parallel to the incoming surface or along a direction perpendicular to the incoming surface and the one surface on which the plurality of prisms is formed.

According to another aspect of the present invention, a light guiding panel formed of a transparent member and into a plate shape and capable of displaying a plurality of patterns is provided. The light guiding panel has: an incoming surface formed on one of side surfaces of the light guiding panel so as to face a plurality of light sources; a reflective surface formed on at least one of the other side surfaces of the light guiding panel, the reflective surface reflecting light emitted from any one of the plurality of light sources and entering the light guiding panel through the incoming surface, and changing a propagation direction of the light; and a plurality of prisms which is formed on one surface of the light guiding panel for each of the plurality of patterns, is arrayed along the pattern, is oriented toward light emitted from a light source which is included in the plurality of light sources and which corresponds to the pattern, entering the light guiding panel through the incoming surface, and directed to the pattern, and reflects the light so that the light is emitted through the other surface of the light guiding panel.

Effect of the Invention

The display device according to the present invention provides an effect of reducing the visibility of patterns other than the pattern corresponding to the light source that emits light, in the plurality of patterns, even when the light source can be arranged only along one side surface of the light guiding panel.

MODE FOR CARRYING OUT THE INVENTION

A display device according to an embodiment of the present invention will now be described with reference to the drawings. This display device has a light guiding panel obtained by forming a material transparent to light emitted from a plurality of light sources into a plate shape, and one of the surfaces of the light guiding panel is formed as an outgoing surface facing a viewer. Further, one of the side surfaces surrounding the outgoing surface of the light guiding panel is formed as an incoming surface facing the plurality of light sources. At least one of the side surfaces of the light guiding panel other than the incoming surface is formed as a reflective surface that reflects light emitted from the corresponding light source in the plurality of light sources and entering the light guiding panel, and changes a propagation direction of the light.

The light guiding panel is provided with: a plurality of patterns that corresponds one-to-one with the plurality of light sources; and a plurality of prisms that is provided along each of the plurality of patterns on the other surface of the light guiding panel on the side opposite to the outgoing surface, and that reflects light emitted from the corresponding light source and entering the light guiding panel toward the outgoing surface. Each of the prisms arrayed along a pattern which is included in the plurality of patterns and which corresponds to the light source emitting light which is to be reflected by the reflective surface is arrayed to be oriented toward the propagation direction of light reflected by the reflective surface. This enables the prisms arrayed for each pattern along the pattern to be oriented in greatly different directions, whereby the display device can reduce the visibility of patterns other than the pattern corresponding to the light source that emits light in the plurality of patterns.

In the following, for convenience of description, the side facing the viewer is defined as a front side and the opposite side is defined as a back side.

FIG. 1is a diagram schematically showing a configuration of a display device according to one embodiment of the present invention. The display device1includes a light guiding panel2, three light sources3-1to3-3, a collimating lens4, a storage5, and a controller6.

The light guiding panel2is a plate-shaped member that is transparent to light emitted from the light sources3-1to3-3. The light guiding panel2is formed by molding a resin that is transparent to visible light, such as polymethyl methacrylate (PMMA), polycarbonate, or cycloolefin polymer. The light guiding panel2is provided with three patterns21to23that can be displayed by turning on the light sources3-1to3-3. That is, the light guiding panel2propagates light from the light source3-1while the light source3-1is turned on, and reflects the light from the light source3-1toward the viewer positioned within a prescribed range of angles with reference to the direction normal to the outgoing surface on the front side by a plurality of prisms (the detail of which will be described later) arrayed on the back side so as to correspond to the light source3-1and to form the pattern21, thereby enabling the viewer to view the luminous pattern21. Similarly, the light guiding panel2propagates light from the light source3-2while the light source3-2is turned on, and reflects the light from the light source3-2toward the viewer positioned within the prescribed range of angles with reference to the direction normal to the outgoing surface on the front side by a plurality of prisms arrayed on the back side so as to correspond to the light source3-2and to form the pattern22, thereby enabling the viewer to view the luminous pattern22. Further, the light guiding panel2propagates light from the light source3-3while the light source3-3is turned on, and reflects the light from the light source3-3toward the viewer positioned within the prescribed range of angles with reference to the direction normal to the outgoing surface on the front side by a plurality of prisms arrayed on the back side so as to correspond to the light source3-3and to form the pattern23, thereby enabling the viewer to view the luminous pattern23.

The detail of the light guiding panel2will be described later.

Each of the light sources3-1to3-3includes at least one light emitting element that emits visible light. In the present embodiment, the light sources3-1to3-3are arranged such that the light emitting surfaces of the light emitting elements face the incoming surface2athat is one of the side walls of the light guiding panel2. The light sources3-1to3-3are arranged in line along the incoming surface2aat different positions. When each light source includes a plurality of light emitting elements, the light emitting elements may be arranged in line along the longitudinal direction of the incoming surface2a.

The light sources3-1to3-3are turned on or off in response to a control signal from the controller6. While the controller6turns on the light source3-1, light emitted from the light source3-1is collimated by the collimating lens4, and then enters the light guiding panel2through the incoming surface2a,.The entered light propagates through the light guiding panel2, is then reflected by a plurality of prisms that forms the pattern21and is provided on a diffusion surface on the back side of the light guiding panel2, and is emitted from the outgoing surface on the front side. Similarly, while the controller6turns on the light source3-2, light emitted from the light source3-2is collimated by the collimating lens4, and then enters the light guiding panel2through the incoming surface2a.The entered light propagates through the light guiding panel2, is then reflected by a plurality of prisms that forms the pattern22and is provided on the diffusion surface on the back side of the light guiding panel2, and is emitted from the outgoing surface on the front side. Further, while the controller6turns on the light source3-3, light emitted from the light source3-3is collimated by the collimating lens4, and then enters the light guiding panel2through the incoming surface2a.The entered light propagates through the light guiding panel2, is then reflected by a plurality of prisms that forms the pattern23and is provided on the diffusion surface on the back side of the light guiding panel2, and is emitted from the outgoing surface on the front side.

The light emitting elements included in the light sources3-1to3-3are, for example, light emitting diodes, incandescent lamps, or fluorescent lamps. The emission colors of the light sources3-1to3-3may be the same or different from each other. Further, the emission luminance of the light sources3-1to3-3may be the same or different from each other.

The collimating lens4is disposed between the light sources3-1to3-3and the incoming surface2a,and collimates light emitted from the light emitting elements included in the light sources3-1to3-3. When each of the light sources has a plurality of light emitting elements arrayed in line along the longitudinal direction of the incoming surface2a,the collimating lens4may also be formed as a lens array having a plurality of lenses arrayed in line along the longitudinal direction of the incoming surface2a.The lenses are provided to correspond one-to-one with the light emitting elements, and each of the lenses collimates light emitted from the corresponding one of the light emitting elements so that the light perpendicularly enters the incoming surface2a.

The collimating lens4may be configured as a refractive lens or may be configured as a diffractive lens such as a Fresnel zone plate. Further, the collimating lens4may be a cylindrical lens that collimates light from the corresponding light source only in the longitudinal direction of the incoming surface2a.

The storage5includes, for example, a volatile or nonvolatile memory circuit. The storage5stores turn-on control information indicating turn-on sequence or timings of turning on and off the light sources3-1to3-3.

The controller6includes, for example, a processor and driving circuits for the light sources3-1to3-3. The controller6controls on and off of the light sources3-1to3-3according to the turn-on control information.

For example, the controller6turns on the light source3-1and turns off the light sources3-2and3-3for making only the pattern21visible to the viewer positioned within a prescribed range of angles with reference to the direction normal to the outgoing surface of the light guiding panel2on the front side of the light guiding panel2. To make only the pattern22visible to the viewer, the controller6turns off the light sources3-1and3-3and turns on the light source3-2. To make only the pattern23visible to the viewer, the controller6turns off the light sources3-1and3-2and turns on the light source3-3. To make two or more of the patterns21to23visible to the viewer at the same time, the controller6may simultaneously turn on the light sources corresponding to the patterns to be displayed. For example, to make both the pattern21and the pattern22visible to the viewer at the same time, the controller6may simultaneously turn on the light sources3-1and3-2.

The timings at which the light sources3-1to3-3are turned on or off are designated by the turn-on control information. The turn-on control information can be, for example, data in which an identification number that identifies the light source to be turned on is simply represented according to the turn-on sequence of the light sources3-1to3-3. For example, suppose that the identification number of the light source3-1is “1”, the identification number of the light source3-2is “2”, and the identification number of the light source3-3is “3”. Each light source is turned on for each preset period in the sequence of light source3-1→light source3-2→light source3-3, and each light source is turned on repeatedly at regular intervals. In this case, the turn-on control information may have the identification numbers in the sequence of “1”, “2”, and “3”.

The detail of the light guiding panel2will be described below.

FIG. 2is a schematic front view of the light guiding panel2.FIG. 3is a schematic side sectional view of the light guiding panel2taken along a line indicated by an arrow AA′ inFIG. 2. As shown inFIGS. 2 and 3, one of the side surfaces of the light guiding panel2is formed as the incoming surface2afacing the light sources3-1to3-3. Light emitted from the light sources3-1to3-3is collimated by the collimating lens4, and then enters the light guiding panel2through the incoming surface2a.

A plurality of prisms11arrayed along each of the patterns21to23is formed on the diffusion surface2blocated on the back side of the light guiding panel2. Each prism11reflects light which is emitted from the corresponding one of the light sources3-1to3-3, enters the light guiding panel2, and propagates through the light guiding panel2, and causes the reflected light to be emitted through the outgoing surface2cwhich is on the side opposite the diffusion surface2band which is located on the front side of the light guiding panel2.

Further, the two side surfaces of the light guiding panel adjacent to the incoming surface2aof the light guiding panel2are each formed such that a part closer to the side surface opposite the incoming surface2ais tapered, and the tapered parts2dand2eare formed as reflective surfaces. The reflective surface2dtotally reflects light from the light source3-1propagating through the light guiding panel2and changes the propagation direction of the light. For example, if the angle between the incoming surface2aand the reflective surface2dis 45°, light from the light source3-1reflected by the reflective surface2dpropagates in a direction substantially parallel to the longitudinal direction of the incoming surface2a.Similarly, the reflective surface2etotally reflects light from the light source3-3propagating through the light guiding panel2and changes the propagation direction of the light. For example, if the angle between the incoming surface2aand the reflective surface2eis 45°, light from the light source3-3reflected by the reflective surface2epropagates in a direction substantially parallel to the longitudinal direction of the incoming surface2aand in a direction opposite to the propagation direction of light emitted from the light source3-1and reflected by the reflective surface2d.

As described above, the prisms11are arrayed along the patterns21to23, respectively. Each prism11arrayed in the pattern21reflects light which is emitted from the light source3-1, enters the light guiding panel2through the incoming surface2a,and then reflected by the reflective surface2dtoward the viewer, that is, toward the direction within the prescribed range of angles with reference to the direction normal to the outgoing surface2cof the light guiding panel2. For this purpose, each of the prisms11arrayed along the pattern21is formed so that the reflective surface thereof is oriented toward the propagation direction of light emitted from the light source3-1and reflected by the reflective surface2d.For example, as described above, if the angle between the incoming surface2aand the reflective surface2dis 45°, each prism11arrayed along the pattern21may be formed such that the reflective surface thereof faces the reflective surface2dand is perpendicular to the incoming surface2ain a plane parallel to the diffusion surface2b.

Further, each prism11arrayed in the pattern22reflects light which is emitted from the light source3-2and enters the light guiding panel2through the incoming surface2atoward the direction within the prescribed range of angles with reference to the direction normal to the outgoing surface2cof the light guiding panel2. For this purpose, each of the prisms11arrayed along the pattern22is arrayed so that the reflective surface thereof is substantially parallel to the incoming surface2ain the plane parallel to the diffusion surface2b,that is, the reflective surface thereof faces any one of the light emitting elements of the light source3-2.

Further, each prism11arrayed in the pattern23reflects light which is emitted from the light source3-3, enters the light guiding panel2through the incoming surface2a,and is then reflected by the reflective surface2etoward the direction within the prescribed range of angles with reference to the direction normal to the outgoing surface2cof the light guiding panel2. For this purpose, each of the prisms11arrayed along the pattern23is formed so that the reflective surface thereof is oriented toward the propagation direction of light emitted from the light source3-3and reflected by the reflective surface2e.For example, as described above, if the angle between the incoming surface2aand the reflective surface2eis 45°, each prism11arrayed along the pattern23may be formed such that the reflective surface thereof faces the reflective surface2eand is perpendicular to the incoming surface2ain a plane parallel to the diffusion surface2b.

Due to the prisms11being formed as described above, the viewer can view the pattern21that appears to emit light on the surface of the light guiding panel2while the light source3-1is turned on. Similarly, the viewer can view the pattern22that appears to emit light on the surface of the light guiding panel2while the light source3-2is turned on. Further, the viewer can view the pattern23that appears to emit light on the surface of the light guiding panel2while the light source3-3is turned on. It should be noted that, inFIGS. 2 and 3, the size of each prism and the thickness of the light guiding panel2are exaggerated for clarity of drawings.

The prisms included in the plurality of prisms11and forming the pattern21are arrayed in a staggered or lattice pattern within the pattern21, or randomly arrayed so that the array density of the prisms is constant within the pattern21. Similarly, the prisms included in the plurality of prisms11and forming the pattern22are arrayed in a staggered or lattice pattern within the pattern22, or randomly arrayed so that the array density of the prisms11is constant within the pattern22. Further, the prisms included in the plurality of prisms11and forming the pattern23are arrayed in a staggered or lattice pattern within the pattern23, or randomly arrayed so that the array density of the prisms11is constant within the pattern23.

In a region where any two or more of the patterns21to23overlap, the prisms that respectively form the overlapping patterns may be arrayed.

Note that the prisms11forming the pattern21, the prisms11forming the pattern22, and the prisms11forming the pattern23can be formed to have the same configuration except for only the orientation and arrangement.

FIG. 4Ais a schematic front view of the prism11, andFIG. 4Bis a schematic perspective view of the prism11.FIG. 4Cis a schematic side view of the prism11.FIG. 4Dis a schematic sectional view of the prism11along a line BB′ inFIG. 4A. The prism11is formed, for example, as a triangular pyramid groove having the diffusion surface2bas a bottom surface. One of the three inclined surfaces of the prism11is formed as a reflective surface11a having a predetermined angle with respect to the diffusion surface2b.The predetermined angle is set such that light from the corresponding light source (for example, the light source3-1in the case of prisms forming the pattern21) entering the light guiding panel2is totally reflected and directed in the direction within the prescribed range of angles with reference to the direction normal to the outgoing surface2c.The other two of the three inclined surfaces of the prism11are formed as diffusion surfaces11band11cthat reflect light not from the corresponding light source (for example, light from the light source3-2or3-3in the case of prisms forming the pattern21) toward a direction outside the prescribed range of angles with reference to the direction normal to the outgoing surface2cso that the viewer cannot view the light.

Referring back toFIG. 2, the prisms included in the plurality of prisms11and forming the pattern21are arrayed such that, for example, the reflective surfaces11aare substantially perpendicular to the incoming surface2ain the plane parallel to the diffusion surface2bin order that the reflective surfaces11a are oriented toward the propagation direction of light emitted from the light source3-1and reflected by the reflective surface2d.Similarly, the prisms included in the plurality of prisms11and forming the pattern22are arrayed such that the reflective surfaces11aface any of the light emitting elements of the light source3-2, that is, the reflective surfaces11aand the incoming surface2aare substantially parallel to each other in the plane parallel to the diffusion surface2b.Further, the prisms included in the plurality of prisms11and forming the pattern23are arrayed such that the reflective surfaces11aare substantially perpendicular to the incoming surface2ain the plane parallel to the diffusion surface2bin order that the reflective surfaces are oriented toward the propagation direction of light emitted from the light source3-3and reflected by the reflective surface2e.

As a result, light emitted from the light source3-1, entering the light guiding panel2, and directed to any one of the prisms forming the pattern21is reflected by the reflective surface11a of the prism and emitted through the outgoing surface2cof the light guiding panel2toward the viewer positioned on the front side of the light guiding panel2. On the other hand, light emitted from the light source3-2or3-3, entering the light guiding panel2, and directed to any one of the prisms forming the pattern21is reflected by the diffusion surface11bor11cof the prism toward a direction outside the prescribed range of angles with reference to the direction normal to the outgoing surface2cof the light guiding panel2so as not to be visible to the viewer.

Here, the direction in which the light emitted from the light source3-2or3-3and entering the light guiding panel2is reflected by the diffusion surface11bor11cof the prism forming the pattern21is determined by a combination of an angle (hereinafter referred to as a rotation angle for convenience)8between the direction perpendicular to the propagation direction of light emitted from the light source3-1and reflected by the reflective surface2d,that is, the direction perpendicular to the incoming surface2a,and the diffusion surface11bor11cof the prism, and an angle (hereinafter referred to as an inclination angle for convenience) a between the diffusion surface2bof the light guiding panel2and the diffusion surface11bor11cof the prism. Further, the angle of the reflected light with respect to the direction normal to the outgoing surface2cwhen the reflected light is emitted from the light guiding panel2is affected by the refractive index of the material of the light guiding panel2. Similarly, the direction in which light emitted from the light source3-3and entering the light guiding panel2is reflected by the diffusion surface11bor11cof the prism is also determined by the combination of the rotation angle θ and the inclination angle α. Further, the angle of the reflected light with respect to the direction normal to the outgoing surface2cwhen the reflected light is emitted from the light guiding panel2is affected by the refractive index of the material of the light guiding panel2.

For example, suppose that the direction in which the viewer is positioned, that is, the prescribed range of angles with reference to the direction normal to the outgoing surface2cof the light guiding panel2, is within 30° from the direction normal to the outgoing surface2cof the light guiding panel2. In this case, when the light guiding panel2is formed of polycarbonate (having a refractive index of 1.59) or PMMA (having a refractive index of 1.49), each prism11is preferably formed such that the rotation angle θ is within the range of 25° to 65° and the inclination angle α is within the range of 25° to 55° in order to cause light emitted from a light source other than the corresponding light source and reflected by the prism11to be directed in a direction outside the prescribed range of angles to prevent the light from being directed to the viewer.

Further, suppose that the prescribed range of angles with reference to the direction normal to the outgoing surface2cof the light guiding panel2is within 45° from the direction normal to the outgoing surface2cof the light guiding panel2. In this case, when the light guiding panel2is formed of polycarbonate or PMMA, each prism11is preferably formed such that the rotation angle θ is within the range of 35° to 55° and the inclination angle α is within the range of 25° to 55° in order to cause light emitted from a light source other than the corresponding light source and reflected by the prism11to be directed in a direction outside the prescribed range of angles.

Furthermore, suppose that the prescribed range of angles with reference to the direction normal to the outgoing surface2cof the light guiding panel2is within 60° from the direction normal to the outgoing surface2cof the light guiding panel2. In this case, when the light guiding panel2is formed of polycarbonate or PMMA, each prism11is preferably formed such that the rotation angle θ is within the range of 40° to 50° and the inclination angle α is within the range of 25° to 55° in order to cause light emitted from a light source other than the corresponding light source and reflected by the prism11to be directed in a direction outside the prescribed range of angles.

The rotation angle and inclination angle of the diffusion surfaces of the prisms11in the patterns22and23may be set similarly.

As described above, in the display device, at least one of the side surfaces of the light guiding panel other than the incoming surface is formed as a reflective surface that totally reflects light emitted from the corresponding light source in the plurality of light sources and entering the light guiding panel, and changes a propagation direction of the light. Each of the prisms arrayed along a pattern which is included in the plurality of patterns formed on the light guiding panel and which corresponds to the light source emitting light which is to be reflected by the reflective surface of the light guiding panel is arrayed to be oriented toward the propagation direction of light reflected by the reflective surface. Thus, the prisms arrayed for each of the patterns along the pattern are oriented in different directions, whereby the display device can reduce the visibility of patterns other than the pattern corresponding to the light source that emits light in the plurality of patterns. In particular, this display device can reduce the visibility of patterns other than the pattern to be displayed even if a plurality of patterns is closely arranged or arranged so as to overlap each other.

According to a modification, the reflective surface of the light guiding panel2may be stepped.

FIGS. 5A and 5Bare partially enlarged views of a light guiding panel2according to the modification. In the example shown inFIG. 5A, a reflective surface2dof the light guiding panel2is stepped along a direction parallel to an incoming surface2a.Therefore, as compared with the example shown inFIG. 2, the reflective surface2dcomes closer to a reflective surface2ewith nearness to the side surface on the side opposite the incoming surface2a,whereby the light guiding panel2can be downsized.

In the example shown inFIG. 5B, a part of a reflective surface2dcloser to an incoming surface2ais stepped along the direction perpendicular to the incoming surface2aand perpendicular to a diffusion surface2b.Thus, the width of light emitted from the light source3-1and reflected by the reflective surface2din the direction perpendicular to the incoming surface2acan be increased. Accordingly, the length of the light guiding panel2along the longitudinal direction of the incoming surface2acan be shortened, compared to the case where such a step is not provided under the condition that the width of such light is the same.

According to another modification, a light guiding panel may be formed such that light emitted from any one of the light sources is reflected by two or more reflective surfaces formed on the light guiding panel, and then directed toward a viewer by a prism that forms a pattern.

FIG. 6is a view schematically showing the configuration of a light guiding panel according to this modification. According to this modification, one of the side surfaces of a light guiding panel31is formed as an incoming surface2a,and three reflective surfaces2dto2fare formed on the other side surfaces of the light guiding panel31. Further, the light guiding panel31is provided with four patterns21to24. As in the above embodiment, a plurality of prisms11that causes light propagating through the light guiding panel31to be emitted toward the viewer through an outgoing surface2cis arrayed along each of the patterns. Further, four light sources3-1to3-4are arranged in line along the longitudinal direction of the incoming surface2a.The light sources3-1to3-4correspond one-to-one with the patterns21to24, and are used to display the corresponding patterns. A collimating lens4is disposed between the light sources3-1to3-4and the incoming surface2a.Accordingly, light emitted from the light sources3-1to3-4is collimated by the collimating lens4, and the collimated light enters the light guiding panel31through the incoming surface2a.

Similar to the above embodiment, the reflective surface2dtotally reflects light emitted from the light source3-1and entering the light guiding panel31through the incoming surface2a,and directs the light toward the prisms11forming the pattern21. Similarly, the reflective surface2etotally reflects light emitted from the light source3-4and entering the light guiding panel31through the incoming surface2a,and directs the light toward the prisms11forming the pattern24, as in the abovementioned embodiment. Light emitted from the light source3-3and entering the light guiding panel31through the incoming surface2ais reflected toward the viewer by each prism11forming the pattern23.

Further, in this modification, the reflective surface2fis formed on the side surface on the side opposite the incoming surface2aso as to face the reflective surface2d.Therefore, light emitted from the light source3-2and entering the light guiding panel31through the incoming surface2ais reflected by the reflective surface2dand then reflected again by the reflective surface2ftoward a region where the pattern22is formed. For example, if the angle between the reflective surface2dand the incoming surface2ais 45° and the angle between the reflective surface2dand the reflective surface2fis 90°, light emitted from the light source3-2and reflected again by the reflective surface2fis directed to the incoming surface2aalong the direction normal to the incoming surface2a.Then, the light reflected again by the reflective surface2fis reflected toward the viewer by each prism11forming the pattern22.

In this example, the reflective surface2dis formed so as to reflect both light from the light source3-1and light from the light source3-2. That is, one reflective surface2dchanges the propagation direction of light beams from the two light sources, and thus, the structure of the light guiding panel31is simplified while light beams from the respective light sources can be propagated in different directions.

As described above, according to this modification, the display device enables, for each of the four patterns, light from the light source that illuminates the corresponding pattern to propagate in different directions. Therefore, this display device can reduce the visibility of patterns other than the pattern corresponding to the light source that emits light in the four patterns. In particular, the display device can also direct light emitted from any of the light sources and entering the light guiding panel toward the incoming surface by reflecting the light on the two reflective surfaces. Therefore, this display device more reliably prevents the pattern corresponding to the light source from being visible by light emitted from another light source by setting the orientation of each prism forming the pattern to be reverse to the incoming surface.

FIG. 7is a view schematically showing the configuration of a light guiding panel according to still another modification. In a light guiding panel41according to this modification, seven reflective surfaces2dto2jare formed on the side surfaces other than an incoming surface2a.The reflective surfaces2dto2jare oriented in different directions. Therefore, the light guiding panel41can direct light beams emitted from a plurality of light sources and entering through the incoming surface2ain different directions by the respective reflective surfaces. Thus, even if more patterns than in the above embodiment and modifications are provided, the light guiding panel41can reduce the visibility of patterns other than the pattern corresponding to the light source that emits light due to the configuration in which the light sources and the patterns are formed to correspond one-to-one with the reflective surfaces.

The reflective surface may not totally reflect light entering the reflective surface, depending on the direction of the light. Therefore, a reflective film formed of a metal thin film or a multilayer film may be provided on the reflective surface of the light guiding panel in which an angle of incidence of light from the corresponding light source is smaller than the critical angle of total reflection.

According to still another modification, instead of two prisms respectively corresponding to light beams entering from two directions through two incoming surfaces orthogonal to each other, a prism may be used in which inclined surfaces oriented toward the two directions are formed as reflective surfaces. Similarly, instead of three or four prisms respectively corresponding to light beams from three or four directions, a prism may be used which is formed into a square pyramid shape and which has reflective surfaces formed on the respective inclined surfaces.

FIGS. 8A and 8Bare views showing an example of the shape of a prism according to this modification. A prism12shown inFIG. 8Ais formed into a triangular pyramid shape, and two of the three inclined surfaces are formed as reflective surfaces12aand12b.The prism12is used instead of the prism formed in such a way that the reflective surface is oriented toward light emitted from the light source3-1, reflected by the reflective surface2d,and directed toward the pattern21, and the prism formed in such a way that the reflective surface is oriented toward light emitted from the light source3-2, entering the light guiding panel2through the incoming surface2a,and propagating through the light guiding panel2along the direction normal to the incoming surface2ainFIG. 2. In this case, the reflective surface12aof the prism12is formed so as to be oriented toward light which is directed to the pattern21from the reflective surface2d,and the reflective surface12bis formed to face the incoming surface2a.Therefore, on the diffusion surface26bof the light guiding panel2, the reflective surface12aand the reflective surface12bare orthogonal to each other. The remaining one of the three inclined surfaces of the prism12is formed as a diffusion surface12cwhich is inclined with respect to the propagation direction of light which is emitted from the light source3-3and reflected by the reflective surface2e.Thus, the prism12reflects light emitted from the light source3-1and entering the light guiding panel2toward the viewer positioned on the front side of the light guiding panel2by the reflective surface12a,and light emitted from the light source3-2and entering the light guiding panel2toward the viewer positioned on the front side of the light guiding panel2by the reflective surface12b.On the other hand, light emitted from the light source3-3, entering the light guiding panel2, and reflected by the reflective surface2eis reflected by the diffusion surface12ctoward a direction outside the prescribed range of angles with reference to the direction normal to the outgoing surface2c.

The prism12may be arrayed so that the two reflective surfaces12aand12bare respectively oriented toward the incoming surface2aand toward the propagation direction of light emitted from the light source3-3and reflected by the reflective surface2e.In this case, the prism12reflects light emitted from the light source3-2and entering the light guiding panel2toward the viewer positioned on the front side of the light guiding panel2by the reflective surface12a,and light emitted from the light source3-3and entering the light guiding panel2toward the viewer positioned on the front side of the light guiding panel2by the reflective surface12b.On the other hand, light emitted from the light source3-1, entering the light guiding panel2, and reflected by the reflective surface2dis reflected by the diffusion surface12ctoward a direction outside the prescribed range of angles with reference to the direction normal to the outgoing surface2c.

A prism13shown inFIG. 8Bis formed into a square pyramid shape, and the four inclined surfaces are formed as reflective surfaces13ato13d,respectively. The prism13is used instead of, for example, the prism formed in such a way that the reflective surface is oriented toward the propagation direction of light emitted from the light source3-1, entering the light guiding panel2, and reflected by the reflective surface2d,the prism formed in such a way that the reflective surface faces any one of the light emitting elements of the light source3-2, and the prism formed in such a way that the reflective surface is oriented toward the propagation direction of light emitted from the light source3-3, entering the light guiding panel2, and reflected by the reflective surface2e.In this case, the prism13may be arrayed such that, for example, three of the reflective surfaces are oriented toward: the propagation direction of light emitted from the light source3-1, entering the light guiding panel2, and reflected by the reflective surface2d;the incoming surface2a;and the propagation direction of light emitted from the light source3-3, entering the light guiding panel2, and reflected by the reflective surface2e,respectively.

According to this modification, the display device can reduce the number of prisms arrayed in each pattern. Therefore, the processing of the light guiding panel is facilitated. Moreover, due to the decrease in number of the prisms, a decrease in the density of the reflective surface of the prism per light source can be suppressed, whereby a decrease in brightness of the region where the multiple patterns overlap can be suppressed.

FIG. 9is a schematic front view of a prism formed on a light guiding panel according to still another modification. A prism14according to this modification is different from the prism11according to the above-described embodiment in that a reflective surface14aof the prism14is formed in a curved surface having a convex surface. Thus, the direction of reflection changes depending on the position where light emitted from the light source and propagating through the light guiding panel enters the reflective surface14a,so that the range in which the viewer can view light emitted from the light guiding panel2is widened. Therefore, the viewing angle at which the pattern corresponding to the light source that is turned on can be viewed is widened.

FIG. 10Ais a schematic front view of a prism formed on a light guiding panel according to still another modification, andFIG. 10Bis a schematic side view of the prism according to this modification. In this modification, a prism15is formed as a triangular prism groove on the diffusion surface2bof the light guiding panel. One of the two inclined surfaces of the prism15is formed as a reflective surface15athat reflects light from the corresponding light source toward a direction outside a prescribed range of angles with reference to the direction normal to the outgoing surface, and the other of the two inclined surfaces is formed as a diffusion surface15bthat reflects light from another light source toward a direction different from the direction in which a viewer is positioned. In this modification, the prism15is formed so that the inclination angle of the diffusion surface15bis smaller than the inclination angle of the reflective surface15a.Therefore, the angle between the direction of light reflected by the diffusion surface15band the direction normal to the outgoing surface2cof the light guiding panel2is greater than the angle between the direction of light reflected by the reflective surface15aand the direction normal to the outgoing surface2cof the light guiding panel2. Therefore, the light reflected by the diffusion surface15bis not viewed by a viewer positioned on the front side of the light guiding panel2, or is totally reflected by the outgoing surface2cof the light guiding panel2and is not emitted from the light guiding panel2.

According to still another modification, in order to display a pattern having gradation by changing the brightness of the pattern for each local area, the size of the reflective surface of each prism may be changed for each local area. For example, the prisms may be arrayed such that the prism disposed in a brighter region in the pattern has a greater reflective surface.

Alternatively, in order to display a pattern having gradation, the arrangement density of prisms may be changed for each local area. For example, the prisms may be arrayed such that the arrangement density of the prisms is increased in a brighter region of the pattern.

According to still another modification, in order to make the displayed pattern glitteringly bright, each prism may be arrayed such that the angle between the direction in which the prism faces the light source and the reflective surface is randomly changed for each prism within a prescribed range of angles. In that case, each prism may be rotated or the prism may be formed so that only the reflective surface rotates. The prescribed range of angles only has to be set according to the range of angles in which the viewer can view the pattern with reference to the direction normal to the outgoing surface of the light guiding panel. For example, it only has to be set to a range from about ±5° to about ±10°.

The display device according to the above-described embodiment or modifications may be mounted on a game machine such as a pinball game machine or a slot game machine.

FIG. 11is a schematic perspective view of a pinball game machine provided with the display device according to the embodiment or the modifications as seen from a player side. As shown inFIG. 11, the pinball game machine100is provided with a game board101which is a main body of the game machine provided in most of a region from the upper part to the central part, a ball receiver102disposed below the game board101, an operation unit103having a handle, a liquid crystal display104provided at a substantially central part of the game board101, and a display device105disposed in front of the liquid crystal display104.

The pinball game machine100also has accessories106arranged below the game board101or around the display device105on the front surface of the game board101in order to add excitement to the game. A rail107is disposed on the side of the game board101. Many obstacle nails (not shown) and at least one prize-winning device108are provided on the game board101.

The operation unit103launches a game ball with a predetermined force from a launching device (not shown) according to an amount of rotation of the handle operated by a player. The launched game ball moves upward along the rail107and falls between a large number of obstacle nails. When a sensor (not shown) detects that a game ball has entered any prize-winning device108, a main control circuit (not shown) provided on the back of the game board101causes a ball discharge device (not shown) to discharge, into the ball receiver102, a predetermined number of game balls according to the prize-winning device108into which the game ball enters. Further, the main control circuit drives the liquid crystal display104and the display device105via an effect CPU (not shown) provided on the back of the game board101. Then, the effect CPU transmits to the display device105a control signal including turn-on control information corresponding to the game state.

The display device105is an example of the display device according to the above-described embodiment or modifications, and is attached to the game board101so that the outgoing surface of the light guiding panel faces the player. Furthermore, in this example, the position where the light source can be arranged is limited to one side above the display device105due to, for example, the shape of the accessories106around the display device105etc., and thus, the display device105is mounted such that the light sources of the display device105are positioned above the display device105. Then, the controller of the display device105sequentially changes the light source to be turned on according to the turn-on control information included in the control signal from the effect CPU, so that the player can see a pattern that dynamically changes in response to the light source which is turned on, as well as an image displayed in the liquid crystal display104. Alternatively, the controller may turn off all the light sources so that the player can view only an image displayed on the liquid crystal display104via the light guiding panel.

As described above, those skilled in the art can make various modifications in accordance with the embodiment to be implemented within the scope of the present invention.

DESCRIPTION OF SYMBOLS

collimating lens

storage

controller

100pinball game machine

104liquid crystal display