JP2003272425A - Front light unit and display device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front light unit capable of eliminating unevenness of the brightness and provide a display device for a vehicle using the front light unit. <P>SOLUTION: The front light unit 50 is equipped with a light guide plate 51 to change the light from a light source 52 to be incident to the edge 51c into a plane light and emit it from one surface 51a of the plate 51 to a device 40 to be illuminated and a brightness correcting plate 54 installed in front of the other surface 51b confronting the mentioned surface 51a and generating approximately a uniform brightness by correcting the brightness gradient of the light emitted from the light guide plate 51. This eliminates the unevenness of the brightness when the device illuminated 40 is viewed through the light guide plate 51 and the brightness correcting plate 54. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front light unit and a vehicular display device using the same.

[0002]

2. Description of the Related Art Generally, a vehicle is equipped with a pointer-type display device for instructing measured values such as vehicle speed and engine speed, and a multi-display device for graphically displaying operation states of electric door mirrors and electric seats. ing.

Although the above-mentioned multi-display device uses a liquid crystal display (LCD) as a display element, when a reflection type liquid crystal display panel is used to reduce power consumption,
A front light unit is provided to illuminate by shining light from the front side of the reflective liquid crystal display panel so that it can be displayed even in a dark place such as at night.

Further, in the above-mentioned pointer type display device, a dial having a scale and indexes such as numbers, letters or symbols on the surface thereof, a pointer arranged in front of the dial, and a measured amount are provided. It is configured to have an inner unit that drives the pointer and a wiring board provided with a circuit pattern and to which the inner unit is fixed.
Some of the pointer-type display devices are provided with a front light unit that illuminates by shining light from the front side of the dial so that the dial can be seen at night as in the daytime.

FIG. 8 is a perspective view showing an example of the structure of a front light unit used in the above-mentioned multi-display device or pointer-type display device. In this example, a front light unit for illuminating a dial of a pointer-type display device of a vehicle is shown. As shown in the figure, the front light unit 50 arranged in front of the dial 40 has a light guide plate 51 made of a transparent resin, a light source 52 for illuminating the edge of the light guide plate 51,
It has a reflector 53 that makes the light of the light source 52 incident on the edge of the light guide plate 51.

One surface (surface on the dial 40 side) 51a of the light guide plate 51 is formed into a flat surface and is an antireflection film (not shown).
Is provided, and a prism array in which prisms are arranged in a sawtooth shape is formed on the other surface (the surface on the side of the driver's viewpoint E) 51b facing the one surface 51a. The light source 52 is
The light source 52 is composed of an LED (light emitting diode), a cold cathode tube, and the like, and light from the light source 52 is reflected by the reflector 53 and is guided to the light guide plate 5.
The light enters the edge 51c parallel to the prism array P of No. 1. The light incident from the edge 51c of the light guide plate 51 or the light incident from the edge 51c and reflected by the one surface 51a of the light guide plate 51 is reflected by the prism array of the other surface 51b and converted into plane light, The light is emitted from the surface 51a toward the dial 40. Then, it is reflected by the dial 40,
The light passes through the light guide plate 51 and reaches the driver's viewpoint E.

[0007]

However, when the dial 40 is illuminated using the above-mentioned front light unit 50, as shown in FIG.
The light emitted from a place near 2 and hitting the dial 40 has a high brightness, and the light emitted from a place far from the light source 52 is emitted from the dial 4.
There is a problem in that the brightness of the light that reaches 0 gradually decreases as the distance from the light source 52 increases, and uneven brightness occurs on the dial 40 when viewed from the driver's viewpoint E side.

In view of the above problems, it is an object of the present invention to provide a front light unit that eliminates uneven brightness and a vehicle display device using the same.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 converts light from a light source incident on an edge into plane light to form an illuminated device from one surface. A light guide plate that emits light, and a brightness correction plate that is disposed in front of the other surface of the light guide plate that faces the one surface, and that corrects the brightness gradient of the light that exits from the light guide plate to make the brightness uniform. The front light unit is characterized by including the.

According to the first aspect of the present invention, the front light unit includes a light guide plate that converts light from a light source incident on an edge into flat light and emits the light from one surface to a device to be illuminated, and a light guide plate. The light guide plate and the brightness correction plate are provided in front of the other surface of the light guide plate, and the brightness correction plate corrects the brightness inclination of the light emitted from the light guide plate to make the brightness uniform. Brightness unevenness when the illuminated device is viewed through the plate is eliminated.

According to a second aspect of the present invention made to solve the above-mentioned problems, one surface of the light guide plate facing the illuminated device side is formed flat and the other surface of the light guide plate is a prism array. It exists in the front light unit characterized by being formed.

According to the invention described in claim 2, the light guide plate comprises:
Since one surface facing the illuminated device side is formed into a flat surface, and the prism array is formed on the other surface,
The light incident on the edge is not directly emitted from the other surface, but is entirely emitted as planar light to the illuminated device side, is reflected by the illuminated device, and then is transmitted through the light guide plate to the other side. Since the light is guided to the viewpoint on the surface side, the light guide plate itself does not emit light and the illuminated device does not easily become visible.

In order to solve the above-mentioned problems, the invention according to claim 3 is characterized in that the brightness correction plate is a smoked resin plate with gradation for correcting the brightness inclination or gradation printing for correcting the brightness inclination. The front light unit according to claim 1 or 2, wherein the front light unit comprises a smoked transparent resin plate.

According to the third aspect of the present invention, the brightness correction plate is made of a smoked resin plate having gradation for correcting the brightness inclination or a transparent resin plate smoked by gradation printing for correcting the brightness inclination. The uneven brightness when the illuminated device is viewed through the light guide plate and the brightness correction plate is eliminated.

According to a fourth aspect of the present invention made to solve the above-mentioned problems, in the smoke, when the light source is turned on, the luminance inclination is corrected, and when the light source is turned off, the illuminated object is illuminated. 4. The front light unit according to claim 3, wherein the device is mounted so that it is almost invisible from the other surface side.

According to the invention described in claim 4, when the light source is turned on, the brightness inclination is corrected, and when the light source is turned off, the illuminated device becomes almost invisible from the other surface side. Since it is included, the illuminated device can be viewed with substantially uniform brightness only when the light source is turned on.

In order to solve the above-mentioned problems, the invention according to claim 5 is characterized in that the device to be illuminated is a liquid crystal display or a dial. Located in the front light unit of.

According to the fifth aspect of the invention, since the illuminated device is the liquid crystal display or the dial, the liquid crystal display or the dial can be viewed with substantially uniform brightness.

In order to solve the above-mentioned problems, the invention according to claim 6 is characterized in that a dial having an index corresponding to the measured value is formed, and an index for indicating the index formed on the dial is provided. A front display unit according to any one of claims 1 to 5, which is arranged in front of the dial and the pointer, and a display device for a vehicle.

According to the sixth aspect of the invention, the vehicular display device has a dial plate on which an index corresponding to a measured value is formed, a pointer indicating the index formed on the dial plate, and a dial plate. And the front light unit according to any one of claims 1 to 5 arranged in front of the pointer, so that uneven brightness in the front light is eliminated and the entire dial has a substantially uniform brightness. You can see.

The invention according to claim 7 made to solve the above-mentioned problems resides in the display device for a vehicle according to claim 6, characterized in that the brightness correction plate also serves as a front cover.

According to the seventh aspect of the invention, since the brightness correction plate also serves as the front cover, an inexpensive vehicle display device can be obtained.

In order to solve the above-mentioned problems, the invention according to claim 8 is characterized in that the brightness correction plate comprises a prism forming a part of a convex lens. Exist.

According to the eighth aspect of the present invention, since the brightness correction plate is composed of the prism forming a part of the convex lens, the entire dial can be viewed with substantially uniform brightness and the window reflection at night can be prevented. can do.

In order to solve the above-mentioned problems, the invention according to claim 9 is characterized in that the dial plate is made of metal, and the display device for a vehicle according to any one of claims 6 to 8. Exist in.

According to the ninth aspect of the invention, since the dial is made of metal, the whole of the metallic dial can be seen with substantially uniform brightness, and the display for vehicles has a metallic and high-class appearance. The device is obtained.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing an embodiment of a front light unit according to the present invention.
In addition, the same components as those of the conventional example shown in FIG. In FIG. 1, a front light unit 50 is arranged in front of a dial 40 as a device to be illuminated, and has a light guide plate 51 made of transparent resin, a light source 52 for illuminating the edge of the light guide plate 51, and a light source 52 for guiding light. And a reflector 53 that is incident on the edge of the light plate 51.

The front light unit 50 also includes a brightness correction plate 54 disposed in front of the light guide plate 51. The brightness correction plate 54 is a smoked resin plate with a gradation that corrects the above-described brightness inclination. That is, the brightness correction plate 54 is made of a smoke-containing resin (acrylic resin or polycarbonate resin mixed with a pigment or the like) formed in a flat plate shape having the same (or larger) dimension as the dial 40, and the light source 52. Smoked with gradation is put in such a manner that the lower transmittance is closer to the lower part, the transmittance increases as the distance from the light source increases, and the higher the transmittance becomes higher at the upper part.

As shown in FIG. 2, one surface (the surface on the dial 40 side) 51a of the light guide plate 51 is formed in a flat surface and provided with an antireflection film (not shown), and faces one surface 51a. On the other surface (the surface on the driver's viewpoint E side) 51b, a prism array P in which prisms are arranged in a sawtooth shape is formed. The light source 52 includes an LED (light emitting diode), a cold cathode tube, and the like, and light from the light source 52 is reflected by a reflector 53.
And is incident on the edge 51c of the light guide plate 51 parallel to the prism array P.

The prism array P of the light guide plate 51 has a reflecting surface P1 on the opposite side of the edge 51c from the apex and an inclined surface P2 on the edge 51c side of the apex. The inclination angle of the reflecting surface P1 is set to the angle at which the light incident from the edge 51c is reflected by the reflecting surface P1 and the reflected light is emitted toward the dial 40. Moreover, the inclination angle of the inclined surface P2 is substantially parallel to the light incident from the edge 51c, and almost no light reflects or transmits this surface. Therefore, the light guide plate 51 itself appears to emit light, and the metal dial plate 4 behind the light guide plate 51 appears.
It is not difficult to see 0.

In the above structure, when the light source 52 is turned on, the light from the light source 52 is reflected by the reflecting surface 5 of the reflector 53.
It is reflected by 3a and is incident on the edge 51c of the light guide plate 51. The light incident from the edge 51c of the light guide plate 51 or the light incident from the edge 51c and reflected by the one surface 51a of the light guide plate 51 is reflected by the prism array P of the other surface 51b, and the light is reflected from one surface 51a. Emit to the plate 40. Then, it is reflected by the dial 40, passes through the light guide plate 51, and reaches the driver's viewpoint E.

That is, in the above-mentioned light guide plate 51,
Since the reflecting surface P1 is alternately provided on the entire light guide plate 51 and the inclined surface P2, the light incident from the light source 52 via the reflector is converted into plane light traveling from the entire reflecting surface P1 toward the dial 40. The dial 40 is emitted toward the dial 40, and the dial 40 can be surface-illuminated.

At this time, as shown in FIG.
Of the light emitted from a place near the light source 52 and hitting the dial 40 has a high luminance, and the brightness of light emitted from a place far from the light source 52 and hitting the dial 40 gradually decreases as the distance from the light source 52 increases. Results in
The light reflected by the dial 40 and transmitted through the light guide plate 51, when transmitted through the brightness correction plate 54, has a brightness slope opposite to the above described brightness slope due to the smoke with gradation, and the brightness caused by the light guide plate 51. The inclination and the luminance inclination by the luminance correction plate 54 are superimposed. As a result, the brightness correction plate 54
The corrected light that has passed through is corrected for uneven brightness, and the dial 40 can be viewed with substantially uniform brightness from the driver's viewpoint E side.

Next, FIGS. 4 and 5 are an exploded perspective view and a sectional view showing an embodiment of a vehicle display device of the present invention using the above-mentioned front light unit, respectively. In the figure, the vehicle display device corresponds to a pointer 10 for instructing a measurement value, a substrate 30 on which a movement 20 that rotationally drives the pointer 10 is mounted, and an instruction for a measurement value instructed by the pointer 10. The dial 40 includes a metal dial 40 on which the index is formed by printing and the like, and a front light unit 50 provided in front of the dial 40 and the pointer 10, that is, on the driver's viewpoint side. The front light unit 50 includes a light guide plate 51, a light source 52,
It has a reflector 53 that allows the light of the light source 52 to enter the edge of the light guide plate 51, and a brightness correction plate 54.

In the front light unit 50, the light guide plate 51 is sandwiched between the front light unit retainer 60 and the dial 70 that hides the inside of the display device except the metal dial plate 40, so that the dial plate 40 is prevented. More favored by the driver's point of view. In addition, a flat brightness correction plate 54 is attached to the opening of the dial 70 also as a front cover so that dust and the like does not enter through the opening.

In the vehicle display device having the above-mentioned structure,
When the light source 52 is turned on, the light emitted from the front light unit 50 as plane light and reflected by the dial 40 causes a brightness inclination due to the light guide plate 51, but when the light is transmitted through the brightness correction plate 54, gradation of light is generated. The brightness is corrected by the applied smoke, and as a result, the uneven brightness when viewed from the driver's viewpoint E side is eliminated, and the dial 40 can be viewed with substantially uniform brightness.

As described above, according to the vehicle display device of the present invention, the uneven brightness in the front light is eliminated, and the entire dial 40 can be viewed with substantially uniform brightness. Further, since the brightness correction plate 54 also serves as the front cover, the vehicular display device can be manufactured at low cost. Further, since the dial plate 40 is made of metal, the whole of the metal dial plate can be viewed with substantially uniform brightness, and a vehicular display device having a metallic feeling and a high-class feeling can be obtained.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications and applications are possible.

For example, in the above-described embodiment, the brightness correction plate 54 is a smoked resin plate with gradation to correct the brightness inclination in the light guide plate 51, but the invention is not limited to this, and a transparent resin plate is used. Alternatively, it is possible to use a smoked one by gradation printing.

Further, the smoke of the brightness correction plate 54 can be put in such a degree that the illuminated device becomes almost invisible from the other surface side when the light source is turned off. In this case, only when the light source is turned on. The illuminated device can be viewed with a substantially uniform brightness.

Further, in the above embodiment of the vehicle display device, the brightness correction plate 54 also serving as the front cover has a flat plate shape, but as another embodiment, for example, as shown in FIG. A prismatic shape (ie,
A shape obtained by cutting the end portion of the convex lens) may be used.

In this case, as shown in FIG. 7, the prism-shaped brightness correction plate 54 serves both to correct brightness and to prevent window reflection at night, so that the prism becomes thicker from top to bottom. Place it, so the smoke is also darker from top to bottom. Therefore, the light source 5
2 is arranged below the dial 40. With the above-described configuration, when the vehicular display device is arranged on the dashboard located below the windshield (not shown), the vehicular display device is reflected from the dial 40 toward the upper part of the vehicular display device, and is displayed by the windshield. The optical axis A that is reflected and reaches the driver's viewpoint is reflected by the prism-shaped brightness correction plate 54.
It can be bent downward like ´. For this reason, even when the dial 40 is illuminated by the front light unit 50 at night, the light hits the windshield and enters the eyes of the driver, and the display image of the dial 40 appears in the window to obstruct the external view. It does not go into a state.

Further, in the above-mentioned embodiment, the dial plate is made of metal, but it is not limited to this and may be made of resin.

Furthermore, in the above-described embodiment, the case where the illuminated device illuminated by the front light unit is the dial is explained, but the invention is not limited to this, and other devices such as a liquid crystal display may be used.

[0045]

As described above, according to the first aspect of the present invention, the uneven brightness when the illuminated device is viewed through the light guide plate and the brightness correction plate is eliminated.

According to the second aspect of the invention, the light incident on the edge is not directly emitted from the other surface, but is entirely emitted as plane light to the illuminated device side once, and the illuminated light is emitted from the illuminated device. After being reflected, the light is transmitted through the light guide plate and guided to the viewpoint on the other surface side, so that the light guide plate itself does not emit light and the illuminated device does not easily become visible.

According to the third aspect of the invention, the uneven brightness when the device to be illuminated is viewed through the light guide plate and the brightness correction plate is eliminated.

According to the fourth aspect of the invention, the illuminated device can be viewed with substantially uniform brightness only when the light source is turned on.

According to the fifth aspect of the invention, the liquid crystal display or dial can be viewed with substantially uniform brightness.

According to the sixth aspect of the invention, the uneven brightness in the front light is eliminated, and the entire dial can be seen with substantially uniform brightness.

According to the invention of claim 7, an inexpensive vehicle display device can be obtained.

According to the eighth aspect of the present invention, the entire dial can be seen with a substantially uniform brightness, and window reflection at night can be prevented.

According to the invention described in claim 9, the whole of the metal dial plate can be seen with substantially uniform brightness, and a vehicular display device having a metallic feeling and a high-class feeling can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a front light unit of the present invention.

FIG. 2 is a schematic view showing a detailed structure of a light guide plate constituting the front light unit of the present invention.

FIG. 3 is a diagram illustrating a brightness correction operation in the front light unit of the present invention.

4 is an exploded perspective view showing an embodiment of a vehicle display device of the present invention using the front light unit of FIG.

5 is a cross-sectional view showing an embodiment of a vehicle display device of the present invention using the front light unit of FIG.

6A and 6B are a perspective view and a front view, respectively, showing another embodiment of the brightness correction plate constituting the front light unit of the present invention.

7 is a sectional view showing another embodiment of the vehicular display device of the present invention using the front light unit using the brightness correction plate of FIG.

FIG. 8 is a perspective view showing an example of a structure of a conventional front light unit.

9A and 9B are diagrams illustrating brightness unevenness in the front light unit of FIG.

[Explanation of symbols]

10 guidelines 40 dial (illuminated device) 50 front light unit 51 light guide plate 51a One side 51b The other side 51c edge 52 light source 53 reflector 54 Brightness correction plate

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 G02F 1/1335 1/13357 1/13357 // F21Y 101: 02 F21Y 101: 02

Claims (9)

[Claims] 1. A light guide plate that converts light from a light source incident on an edge into plane light and emits the light to a device to be illuminated from one surface, and another surface of the light guide plate opposite to the one surface. A front light unit, comprising: a brightness correction plate that is disposed in front of the light guide plate and corrects a brightness gradient of the light emitted from the light guide plate to make the brightness uniform. 2. The front light unit, wherein one surface of the light guide plate facing the illuminated device side is formed to be a flat surface and a prism array is formed to the other surface. 3. The brightness correction plate is made of a smoked resin plate with gradation for correcting the brightness inclination or a transparent resin plate smoked by gradation printing for correcting the brightness inclination. The front light unit according to item 1 or 2. 4. The smoke is put in such a degree that when the light source is turned on, the luminance gradient is corrected, and when the light source is turned off, the illuminated device is almost invisible from the other surface side. The front light unit according to claim 3, wherein: 5. The front light unit according to claim 1, wherein the illuminated device is a liquid crystal display or a dial. 6. A dial which is formed with an index corresponding to the measured value, a pointer which indicates the index formed on the dial, and the dial which is arranged in front of the dial and the pointer. A front light unit according to any one of 1 to 5, and a display device for a vehicle, comprising: 7. The vehicle display device according to claim 6, wherein the brightness correction plate also serves as a front cover. 8. The vehicle display device according to claim 7, wherein the brightness correction plate is formed of a prism that forms a part of a convex lens. 9. The vehicle display device according to claim 6, wherein the dial is made of metal.