Display apparatus

A display apparatus includes a display, a light source, and a light transmittance control means. The display displays a display design. The light source emits a light to illuminate the display. The light transmittance control means is disposed on at least one side of the display and includes a characteristic region for varying an exit angle of the light by varying an incident angle of the light on the light transmittance control means.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2004-66138, filed on Mar. 9, 2004, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a display apparatus for a vehicle and, more particularly, a stereoscopic display apparatus for displaying various pieces of information.

BACKGROUND OF THE INVENTION

A conventional display apparatus includes a transmissive liquid crystal display; light source means for illuminating the transmissive liquid crystal display from the rear side; a diffusion sheet disposed in the rear of the transmissive liquid crystal display, diffusing light from the light source means; and a holder for holding these components. The diffusion sheet not only diffuses the light from the light source means, but also has a predetermined pattern formed on it and is secured to the holder with a certain space between itself and the transmissive liquid crystal display so that the pattern can be viewed through the transmissive liquid crystal display. The conventional display apparatus is described in, for example, Japanese Patent Laid-Open Publication No. Hei 10-340060.

The pattern on the diffusion sheet thereby overlaps with a display image on the liquid crystal display screen and is visible in the background thereof, which aims at enhancing visual effects such as, for example, a sense of depth and a three-dimensional floating effect.

In such a conventional display apparatus, however, since a single flat diffusion sheet or only a single layer is disposed in the rear of a transmissive liquid crystal display, the background of a display Image on the liquid crystal display screen looks two-dimensional. Accordingly, a problem with the conventional display apparatus is that it lacks stereoscopic visual effects.

SUMMARY OF THE INVENTION

The present invention addresses the above-described problem and has an object of providing a display apparatus that can produce enhanced stereoscopic and innovative visual effects by enhancing a sense of depth in the rear of the display plate with a simple structure.

In order to achieve the object described above, the present invention employs the technical means described below.

The display apparatus according to one aspect of the invention includes a display, a light source, and a light transmittance control means. The display displays a display design. The light source is disposed behind the display for illuminating the display. The light transmittance control means is disposed at least on one of a rear and front side of the display. The light transmittance control means has a characteristic region that varies an exit angle of light emitted from the light source by varying an incident angle of the light.

According to this structure, the light from the light source inevitably passes through the light transmittance control means to be viewed by a viewer. That is, part of the light from the light source passes through the characteristic region of the light transmittance control means, in which the exit angle of light Is varied by varying the incident angle of the light from the light source, and is incident on the eyes of the viewer.

When the light from the light source passes through the area other than the characteristic region of the light transmittance control means, the incident angle to both the front and rear faces thereof is about zero degrees, so the amount of light reflected from each of the faces is very small, which indicates that the transmittance becomes nearly 100%.

When the light from the light source passes through the region of the light transmittance control means, in which the exit angle of light is varied by varying the incident angle of the light from the light source, the incident angle to the curved or sloped surface of the region of the light transmittance control means for the light from the light source becomes greater than zero degrees, thereby increasing the amount of the light reflected from the curved or sloped surface. Since this reflected light propagates in a direction different from the direction toward the viewer, it does not incident on the eyes of the viewer. As a result, the amount of light passing through the region of the light transmittance control means and being incident upon the eyes of the viewer decreases, so the curved or sloped surface of the region of the light transmittance control means looks dark as compared to the other region of the light transmittance control means. Therefore, the display is visible such that the brightness of its background is not uniform, but changes partially.

Accordingly, since the background of the display looks as if it has depth in the observation direction, the display apparatus having enhanced stereoscopic and innovative visual effects can be obtained.

In the display apparatus according to another aspect of the invention, the region of the light transmittance control means is disposed so as to surround the display design of the display.

The display design can thereby be displayed on the display as if it stands out against its background toward the viewer side, or as if it backs from its background away from the viewer, so that the display apparatus having enhanced stereoscopic and innovative visual effects can be obtained.

In the display apparatus according to yet another aspect of the invention, the region of the light transmittance control means is disposed in the periphery of the light transmittance control means, and formed so that the incident angle to the region decreases toward the periphery.

When the incident angle of the light from the light source to the region of the light transmittance control means, in which the exit angle of light is varied by varying the incident angle of the light from the light source, is zero degrees, the transmittance to the region becomes the maximum, that is, nearly 100%. The amount of reflection then increases and correspondingly the light transmittance in the region decreases, as the incident angle increases.

Accordingly, if the shape of the region is formed as described above, the transmittance of the region becomes the minimum at the inner periphery thereof and increases toward the outer periphery thereof. That is, the region is viewed such that it becomes gradually brighter from the inner periphery to the outer periphery; in other words, it is visible as a gradation of brightness.

The display apparatus having enhanced stereoscopic and innovative visual effects can thus be obtained.

The display apparatus according to yet another aspect of the invention comprises: a display plate having a display design; a light source disposed In the rear of the display plate; and a diffusion plate disposed between the display plate and the light source, diffusing the light from the light source, wherein the light from the light source passes through the diffusion plate and transmissively illuminates the display plate. In this display apparatus, light transmittance control means is disposed on at least one of the front and rear side of the display plate and has a characteristic region in which an exit angle of light is varied by varying an incident angle of the light from the light source. The characteristic region of the light transmittance control means has a curved surface or a surface sloped with respect to the display plate. The characteristic region is formed in the vicinity of the display design and on a part of at least either the front or rear surface of the light transmittance control means.

With this structure of the display apparatus, when the light emitted from the light source passes through the diffusion plate, it is diffused and reflected within the diffusion plate, thereby exiting the entire surface of the diffusion plate as the light having substantially uniform luminance. In the display apparatus according to the fourth aspect of the invention, the diffusion plate thus functions as a surface light source having uniform luminance. The light exiting the diffusion plate passes through the display plate and then the light transmittance control means, or vice versa, to be incident on the eyes of the viewer. In either case, part of the light exiting the diffusion plate inevitably passes through the characteristic region of the light transmittance control means, in which the exit angle of light is varied by varying the incident angle of the light from the light source, to be incident on the eyes of the viewer.

When the light exiting the diffusion plate passes through the area other than the characteristic region of the light transmittance control means, its incident angle to both the front and rear surfaces thereof is nearly zero degrees, so the amount of reflection from each of the surfaces is very small.

When the light exiting the diffusion plate passes through the characteristic region of the light transmittance control means, the incident angle of the light exiting the diffusion plate to the curved surface or sloped surface of the characteristic region of the light transmittance control means becomes greater than zero degrees, so the amount of reflection on the curved surface or sloped surface increases. As a result, the amount of the light passing through the characteristic region of the light transmittance control means and being incident on the eyes of the viewer decreases, so that the curved surface or sloped surface of the characteristic region of the light transmittance control means looks darker in comparison with the other area thereof. Therefore, the brightness of the background of the display plate is viewed such that it is not uniform, but changes partially.

Accordingly, the background of the display plate looks as if it has depth in the visible direction, so the display apparatus having enhanced stereoscopic and Innovative visual effects can be obtained.

In the display apparatus according to yet another aspect of the Invention, at least a part of the region of the light transmittance control means is formed so as to be projected toward the outside of the light transmittance control means.

In this case, the surface of the part of the characteristic region formed so as to be projected toward the outside of the light transmittance control means becomes a curved surface or a surface sloped with respect to the display plate. Therefore, the same effects as in the display apparatus according to the fourth aspect of the invention can be obtained, so the background of the display plate looks as if it has depth in the visible direction, thereby obtaining the display apparatus having enhanced stereoscopic and innovative visual effects.

The display apparatus according to yet another aspect of the invention has a structure in which a plurality of light transmittance control means are disposed so as to be superposed each other.

In this case, the plurality of light transmittance control means are disposed with certain distances in the observation direction; in other words, they are disposed at positions having different distances from the eyes of the viewer.

The stereoscopic effect of the background of the display plate can thereby be more enhanced, so the display apparatus having enhanced stereoscopic and innovative visual effects can be obtained.

In the display apparatus according to still another aspect of the invention, the light transmittance control means has a through-hole formed in an observation direction, and the region of the transmittance control means is substantially concentrically formed in the periphery of the hole.

In this case, since the hole area in the light transmittance control means has a light transmittance of 100%, the difference or variation of the amount of light transmitting through the region of the light transmittance control means, in which the exit angle of light is varied by varying the incident angle of the light from the light source, and the other area can be more enhanced by an effect of the light transmittance control means that limits the amount of transmitted light.

In the display apparatus according to still another aspect of the invention, the display plate is a transmissive liquid crystal display and the display design is an image displayed on the transmissive liquid crystal display.

In this case, if coloring or the like is performed on a translucent member to reduce the light transmittance, an opening is formed as a clear and colorless area, which becomes the area having a high light transmittance. The peripheral edge of the opening, which is the outline of the design, is thereby perceived by the viewer as the boundary between the areas having different brightness.

Accordingly, since the stereoscopic effect of the background of the display design can be enhanced on the display screen of the transmissive liquid crystal display, the display apparatus having enhanced stereoscopic and innovative visual effects can be obtained.

Other features and advantages of the present invention will be appreciated, as well as methods of operation and the function of the related parts from a study of the following detailed description, appended claims, and drawings, all of which form a part of this application. In the drawings:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The display apparatus of the present invention will now be described with reference to the attached drawings illustrating embodiments in which the invention is applied to a combination meter1installed in an automobile.

The combination meter1is disposed in an instrument panel in the front of the interior of an automobile and displays various pieces of information about the operational state of the automobile on a display screen21of a liquid crystal panel2for the driver to see.

A structure of the combination meter1according to the first embodiment will be described below.

As shown inFIG. 2, the liquid crystal panel2of the transmissive liquid crystal display device is attached by fitting it into an opening9aprovided in a faceplate9of the combination meter1. InFIG. 2, the driver's seat is assumed to be on the right-hand side so that the combination meter1is visible from the right-hand side. The liquid crystal panel2according to the first embodiment is used as a so-called digital speed meter that numerically displays the traveling speed of the automobile as shown inFIG. 1.

In the rear of the liquid crystal panel2, which is on the left-hand side inFIG. 2, a prism plate3of a light transmittance control means is disposed. The prism plate3is formed of a clear and colorless resin such as polycarbonate resin, acrylic resin, or the like. The prism plate3has a recess32formed along a sightline, which originates to the right and looks to the left of the device inFIG. 2. The outline of a bottom area33of the recess32is formed in an elliptical shape, as shown inFIG. 1. A sidewall31of the recess32is provided to serve as a characteristic region of the light transmittance control means. The characteristic region is formed of a curved surface to vary an exit angle of light by varying the incident angle of the light emitted from a light source. The cross-section of the characteristic region is curved, as shown inFIG. 2. In the combination meter1according to the first embodiment, the curve of the characteristic region forms a substantially arc shape. A diffusion sheet5is disposed on a side of the prism plate3that is opposite from the liquid crystal panel2(on the left-hand side of the prism plate3inFIG. 2). The diffusion sheet5diffuses the light from light emitting diodes6of the light source, which will be described later.

The diffusion plate5is made of a translucent material such as polycarbonate resin, acrylic resin, or the like, and is formed in a plate shape having a flat surface substantially identical to that of the liquid crystal panel2. The diffusion plate5possesses a diffusion and reflection layer that diffuses and reflects the light incident from the light emitting diodes6. The diffusion and reflection layer is formed with, for example, a grain surface, a dot printed layer, or a bright color (white, silver, etc.) printed layer. The light incident on the diffusion plates from the light emitting diodes6is reflected from the diffusion and reflection layer to exit the diffusion plate5, thereby obtaining substantially uniform luminance across the entire diffusion plate5. That is, the diffusion plate5functions as a surface light source that emits light with substantially uniform luminance, thereby obtaining substantially uniform luminance across the liquid crystal panel2and creating a combination meter1having good visual effects.

In the rear of the diffusion plate5(on the left-hand side inFIG. 2), the light emitting diodes6of the light source are disposed to transmissively illuminate the liquid crystal panel2. The light emitting diodes6are mounted on and secured to a print board7as shown inFIG. 2. A control circuit10is also mounted on the print board7. The control circuit10drives the liquid crystal panel2according to an external electronic signal, i.e., the detection signal from a car speed sensor13(shown inFIG. 5), to display the car speed, and controls switching of the light emitting diodes6. The control circuit10is configured with, for example, a microcomputer.

The components described above, that is, the liquid crystal panel2, the prism plate3, the diffusion sheet5, and the print board7on which the light emitting diodes6are mounted, are housed and secured in a casing8made of, for example, a plastic material. The casing8is attached to the rear surface of the faceplate9, as shown inFIG. 2.

Next, a function and effect of the sidewall31or its effects on improving the visual effects of the combination meter1, which characterizes the combination meter1according to the first embodiment, will be described with reference toFIGS. 3 and 4. The sidewall31is provided in the prism plate3and serves as the light transmittance control means, and is the characteristic region in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6.

When viewed from along the sightline (right to left direction inFIG. 3), the sidewall31, in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6, is visible as an elliptical ring shape having a certain width, as shown inFIG. 4.

Part of the light, which exits the diffusion plate5and is incident on the prism plate3is incident on the sidewall31provided in the prism plate3. Since the cross-section of the sidewall31is formed in an arc shape, as shown inFIG. 3, when the light exiting the diffusion plate5is Incident on the sidewall31, the incident angle varies depending on the location on the sidewall31. That is, the incident angle has the maximum value at the Inner peripheral edge of the sidewall31near the bottom area33. The incident angle therefore, gradually decreases, as the light is incident on a location away from the bottom area33, i.e., toward the outer periphery of the prism plate3.

At locations in the sidewall31where an incident angle θ1 of the light from the diffusion plate5is greater than a total reflection angle θR of a material of the prism plate3, the light exiting the sidewall31to the liquid crystal plate2is hardly present, as shown inFIG. 3, because the light exiting the diffusion plate5to the sidewall31is totally reflected therefrom. This indicates that light transmittances at these locations become nearly zero.

On the other hand, at locations in the sidewall31where an Incident angle θ2 of the light from the diffusion plate5is less than the total reflection angle θR of a material of the prism plate3, part of the light exiting the diffusion plate5to the sidewall31is reflected therefrom and propagates again therein. The remaining part of the light exits the sidewall31toward the liquid crystal panel2. In this case, the smaller the incident angle θ2 of the light from the diffusion plate5relative to the total reflection angle θR of a material of the prism plate3or, alternatively stated, the nearer the location of the incident light is to the outer periphery of the prism plate3, the more amount of the light exits the sidewall31toward the liquid crystal panel2. That is, the light transmittance increases as the angle of the light incident on the sidewall31decreases relative to the total reflection angle θR.

In summary, the sidewall31, in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6, forms an elliptical ring shape having a certain width as shown inFIG. 4. The light transmittance of the elliptical ring gradually increases from zero near its inner periphery to greater than zero at its outer periphery. The light transmittance then becomes the greatest at the outer periphery of the sidewall31, that is, becomes similar to the transmittance in a flat area disposed radially outside of the sidewall31of the prism plate3. That is, in the prism plate3, the sidewall31is visible as an elliptical ring having a certain width in the bright background having a uniform luminance, the elliptical ring being dark in its inner periphery and becoming gradually brighter toward its outer periphery.

The viewer of the combination meter1according to the first embodiment can thus see the elliptical ring having a certain width, which is dark in the inner periphery and becomes gradually brighter toward the outer periphery, in the background of the liquid crystal panel2.

Generally, when the brightness of a visible object gradually changes, the darker part is perceived as if it were more distant from the viewer.

Accordingly, in the combination meter1according to the first embodiment, the background of the liquid crystal panel2looks as if it becomes more distant from the viewer from the outer periphery to the inner periphery or, in other words, it has a sense of depth in the visible direction.

The combination meter1having enhanced stereoscopic and innovative visual effects can thus be obtained.

Next, an electronic circuit configuration of the combination meter1according to the first embodiment will be described with reference toFIG. 5, which schematically illustrates the electronic circuit configuration.

In the combination meter1according to the first embodiment, power is constantly supplied to a control circuit10from a battery12as shown inFIG. 5. An ignition switch11is also connected to the control circuit10so that its operation states (on and off states) can be detected. The liquid crystal panel2and the light emitting diodes6are also connected to the control circuit10. Further, the car speed sensor13for detecting the running speed of the automobile is connected to the control circuit10so that the control circuit10can receive the detection signal.

After the ignition switch11has been switched on by the driver, the control circuit10turns on the light emitting diodes6. The liquid crystal panel2is thereby transmissively Illuminated so that an image formed on the liquid crystal panel2becomes visible. Simultaneously, the control circuit10drives the liquid crystal panel2on the basis of the detection signal from the car speed sensor13to display the traveling speed of the automobile. Consequently, the traveling speed of the automobile is displayed on the liquid crystal panel2as a digital value, which is transmissively illuminated by the light from light emitting diodes6through the diffusion plate5and clearly viewed by the driver.

As described above, in the combination meter1according to the first embodiment, the prism plate3has the sidewall31with a curved surface, in which the exit angle of light is varied by varying the incident angle of the light emitted from the light emitting diodes6, and is disposed behind the liquid crystal panel2. The light passing through the diffusion plate5from the light emitting diodes6passes through the prism plate3and transmissively illuminates the liquid crystal panel2.

In this case, the sidewall31is visible as an elliptical ring having a certain width, which is dark in the inner periphery and becomes gradually brighter toward the outer periphery.

Accordingly, when the viewer sees the combination meter1according to the first embodiment, the background area of the liquid crystal panel2is viewed as if it becomes more distant from the viewer from the outer periphery to the inner periphery or, in other words, as if a space with depth were present in the rear of the liquid crystal panel2in the visible direction.

The combination meter1having enhanced stereoscopic and innovative visual effects can thus be obtained.

FIG. 6is a cross-sectional view illustrating a combination meter1according to a second embodiment of the present invention.

The combination meter1according to the second embodiment differs from the one according to the first embodiment in the position of the prism plate3. That is, in the combination meter1according to the second embodiment, as shown inFIG. 6, the prism plate3is disposed in front of the liquid crystal panel2or on the viewer side.

In this case, as in the combination meter1according to the first embodiment, the sidewall31in the prism plate3is visible in the bright background with uniform luminance as an elliptical ring having a certain width, which is dark in the inner periphery and becomes gradually brighter toward the outer periphery.

The liquid panel2is viewed as if it were disposed at the deepest position or at the furthest position from the viewer in the space with depth created by an effect of the prism plate3in the visible direction.

The combination meter1having enhanced stereoscopic and innovative visual effects can thus be obtained.

FIG. 7is a cross-sectional view illustrating the combination meter1according to a third embodiment of the present invention.

The combination meter1according to the third embodiment differs from the one according to the first embodiment in the shape of the prism plate3. That is, in the combination meter1according to the third embodiment, the bottom area33in the prism plate3according to the first embodiment is removed to form a through-hole34as shown inFIG. 7.

In this case, as in the combination meter1according to the first embodiment, the sidewall31in the prism plate3is visible in the bright background with uniform luminance as an elliptical ring having a certain width, which is dark in the inner periphery and becomes gradually brighter toward the outer periphery.

Accordingly, when the viewer sees the combination meter1according to the third embodiment, the background area of the liquid crystal panel2looks as if it becomes more distant from the viewer from the outer periphery to the inner periphery or, in other words, as if a space with depth were present in the rear of the liquid crystal panel2in the visible direction.

The combination meter1having enhanced stereoscopic and Innovative visual effects can thus be obtained.

FIG. 8is a cross-sectional view illustrating the combination meter1according to a fourth embodiment of the present invention.

The combination meter1according to the fourth embodiment differs from the one according to the second embodiment in that the prism plate3is structured so as to emit light and display itself. That is, as shown inFIG. 8, a light emitting diode14is mounted on the print board7, and the light emitted from the light emitting diode14is guided into the prism plate3. As shown InFIG. 8, the light from the light emitting diode14is incident onto the prism plate3and reflected from a reflective surface35, after which it is repeatedly reflected from the surface of the liquid crystal panel2and the like until it exits the prism plate3.

In this case, since the prism plate3is transmissively illuminated by the light from the light emitting diode14, the stereoscopic effect of the sidewall31, in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6, is further intensified.

The combination meter1having more enhanced stereoscopic and innovative visual effects can thus be obtained.

In each of the first to fourth embodiments described above, the cross-sectional shape of the sidewall31, which is provided in the prism plate3and is the characteristic region in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6, is formed in an arc shape projected toward the viewer side as shown inFIG. 3, but it is not necessarily restricted to this shape. It may be formed in other shapes. For example, a fifth embodiment shown inFIG. 9Aincludes an elliptical shape oppositely recessed to the viewer side. It may also be formed in a straight line shape sloped with respect to the liquid crystal panel2as provided in a sixth embodiment that is shown inFIG. 9B, or in a combination shape of a curved line C and straight line S as provided in a seventh embodiment that is shown inFIG. 9C.

In each of the first to seventh embodiments described above, the sidewall31, In which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6, is provided on the front side of the prism plate3or on the side toward the viewer, but it is not necessarily restricted to this side. It may be provided on the rear side of the prism plate3or on the side opposite to the viewer as provided in an eighth embodiment and shown inFIG. 10.

In each of the first to seventh embodiments described above, the sidewall31, in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6, is formed inside the flat prism plate3in the thickness direction of the plate, but it may be formed outside the flat prism plate3in the thickness direction of the plate as provided in a ninth embodiment and shown inFIG. 11. In other words, it may be formed so as to project from the surface of the flat prism plate3toward the outside.

FIG. 12is a cross-sectional view of the combination meter1according to a tenth embodiment of the present invention.

In each of the first to ninth embodiments described above, the combination meter1has a single prism plate3.

In the combination meter1according to the tenth embodiment, however, two prism plates, i.e., prism plates3and4, are superposed and disposed behind the liquid crystal panel2.

In this case, the sidewall31in the prism plate3, in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6, and the sidewall region41in the prism plate4of the light transmittance control means are visible such that they partially overlap each other. Therefore, the viewer perceives a more complex stereoscopic shape in the rear of the liquid crystal panel2.

The combination meter1having more enhanced stereoscopic and innovative visual effects can thus be obtained.

FIG. 13is a cross-sectional view of the combination meter1according to an eleventh embodiment of the present invention.

In the combination meter1according to the tenth embodiment described above, the two prism plates3and4are superposed and disposed behind the liquid crystal plane2.

In the combination meter1according to the eleventh embodiment, however, two prism plates3and4are disposed on opposite sides of the liquid crystal panel2. That is, as shown inFIG. 13, the prism plates3and4are disposed on the front and rear sides of the liquid crystal panel2, respectively.

In this case, when the viewer sees the combination meter1, the viewer can have a sense of depth created on both the front and rear sides of the liquid crystal panel2by the visual effects of the sidewall31serving as the light transmittance means in the prism plate3and sidewall region41, in which the exit angle of light is varied by varying the incident angle of the light from the light emitting diodes6. In other words, the liquid crystal panel2is perceived as if it were floating at an intermediate position in the space with depth created in the visible direction.

The combination meter1having more enhanced stereoscopic and innovative visual effects can thus be obtained.

In the combination meter1according to the first to eleventh embodiments described above, the light emitting diodes6and14are used as light sources, but the light source is not necessarily limited to using light emitting diodes. Other types of light sources may be used, such as a light bulb, an electric discharge tube, an electroluminescence (EL) panel, and the like.

In the combination meter1according to the first to eleventh embodiments described above, the running speed of the automobile is digitally displayed on the liquid crystal panel2, but display information is not necessarily limited to the running speed. It may be replaced to other information such as engine rotational speed, time, driving distance, temperature of cooling water, and the like, or these may be added to the display information.

In the combination meter1according to the first to eleventh embodiments described above, the liquid crystal panel2is used as a display plate being transmissively illuminated, but the display plate is not necessarily limited to the liquid crystal panel2. Other types of display members that can be transmissively illuminated may be used.