JP3231497U - Backlight module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight module constituting a character light type license plate having high visibility of a display unit without feeling glare in a dark environment. SOLUTION: This is a backlight module for a character light type license plate using a light emitting diode element as a light source, and the chromaticity coordinates (x / y) of the emission color of the light emitting diode element are shown in the CIE chromaticity diagram. Within the range surrounded by the four coordinates of 0.285 / 0.264, 0.285 / 0.332, 0.440 / 0.382, 0.440 / 0.432, x is 0.41 or more. y is 0.40 or more. [Selection diagram] Fig. 3

Description

The present invention relates to a backlight module used for a character light type license plate.

The character light type number plate irradiates light from the back light module from the back of the display plate on which the display parts such as letters, numbers, and symbols are arranged to improve the visibility of the display part. , A light emitting element such as a commonly used white LED (light emitting diode) is used as a light source, and a light guide plate, a light reflecting plate, a light diffusing plate, etc. for uniformly emitting light from the light source from an exit surface. It is composed of optical components. For example, in Patent Document 1, a plurality of LED elements are arranged along the side wall of a shallow box-shaped case, and light from the LED elements is directed to the opening side of the case via a light guide plate, and further, light diffusion. A configuration that diffuses by a plate is disclosed.

Japanese Unexamined Patent Publication No. 2013-88644

A generally known backlight module emits light from a light source as it is through a light guide plate or a light diffusing plate, and the visibility of display parts such as letters and numbers increases or decreases the amount of light from the backlight module. It was adjusted with. However, the visibility of the display unit depends on the amount of light emitted from the display unit. If the amount of light is too small, the display unit becomes dark and the visibility is low, and as the amount of light increases, the display unit becomes brighter and the visibility becomes higher. Although it is improved, if the amount of light from the display unit is too large, there is a problem that it looks dazzling to the human eye and the visibility is lowered in a dark environment at night.

An object of the present invention is to provide a backlight module that constitutes a highly visible character light type license plate in a dark environment.

The present invention is a backlight module for a character light type license plate that uses a light emitting diode element as a light source.
The chromaticity coordinates (x / y) of the emission color are 0.285 / 0.264, 0.285 / 0.332, 0.440 / 0.382, 0.440 / 0.432 in the CIE chromaticity diagram. It is characterized in that it is located in a region where x is 0.41 or more and y is 0.40 or more within the range surrounded by the four coordinates of.

In the present invention, the following configuration is included as a preferred embodiment.
It has a shallow box-shaped case, a light guide plate, and a light diffusing plate, and a plurality of the light emitting diode elements are arranged in a row.

According to the present invention, since the color tone of the light emitted from the backlight module is adjusted, high visibility of the display unit can be obtained without feeling glare with an appropriate amount of light. Further, the present invention can be easily implemented by changing the emission color of the LED element used in the conventional backlight module or by using an optical filter.

It is a top view which shows the component part of one Embodiment of the backlight module of this invention. It is sectional drawing of the backlight module which assembled the component part of FIG. It is an xy chromaticity diagram which shows the standard of the color tone of the light source of the character light type license plate.

As a result of various studies by the present inventor, the visibility of the display unit in a dark environment is greatly influenced not only by the amount of light from the surroundings of the display unit but also by the color tone, and the color tone of the light emitted from the backlight module is determined. We have found that the visibility of the display unit can be improved by making adjustments, and achieved the present invention.

That is, the present invention is a backlight module for a character light type license plate, and the chromaticity coordinates (x / y) of the emission color are 0.285 / 0.264, 0.285 in the CIE chromaticity diagram. It is located in the range surrounded by the four coordinates of /0.332, 0.440 / 0.382, 0.440 / 0.432, where x is 0.41 or more and y is 0.40 or more. It is particularly characteristic.

The character light type license plate has a thin plate-shaped backlight module and a thin plate-shaped display plate. The display plate has a translucent display unit and a light-shielding substrate. The light-shielding substrate is a plate-like body made of a light-shielding material such as metal, and has a punched hole for attaching the translucent display unit. It is formed. The translucent display unit is a three-dimensional model of the place name display, which is the display content of the license plate, the classification number indicated by numbers, the usage display indicated by hiragana, and the vehicle number indicated by numbers and hyphens. It is made of a light synthetic resin, the top surface is shielded from light, and the side surfaces and the bottom surface following the top surface are translucent. The translucent display unit is attached to a light-shielding substrate so as to project toward the front surface (outer surface) side through a punched hole.

With the above configuration, the light incident on the display plate from the backlight module is incident on the display unit from the bottom surface of the translucent display unit and emitted from the side surface. Therefore, the light from the backlight surrounds the light-shielded top surface of the translucent display unit, and high visibility can be obtained.

Hereinafter, the backlight module of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a component of an embodiment of the backlight module of the present invention, and FIG. 2 is a portion AA'in FIG. 1 of the backlight module in which the component of FIG. 1 is assembled. It is a cross-sectional schematic diagram corresponding to.

The backlight module of the present invention has a light emitting diode (LED) element as a light source, and in the embodiment of FIG. 1, an LED assembly in which a plurality of LED elements are arranged in a row at a predetermined distance is used. ing.

In the embodiment of FIG. 1, it further has a case 10, a light guide plate 20, and a light diffusing plate 40. The case 10 is a shallow box type made of synthetic resin, and houses the LED assembly 30 and the light guide plate 20 inside, and the opening is covered with the light diffusing plate 40. The LED assembly 30 is arranged along the inside of one side surface of the case 10. The inner surface of the bottom surface of the case 10, that is, the surface facing the light guide plate 20, has a light reflection function, and the back surface functions as the back surface of the backlight module. In some cases, a white pigment is mixed with the synthetic resin.

In the embodiment of FIG. 1, in the case 10, the bottom surface of the region where the light guide plate 20, the LED assembly 30, and the wiring of the LED assembly 30 are arranged is a recess 11. Further, 14 is a reinforcing rib, 13 is a screw hole for integrating the backlight module and the display plate (not shown), and 15 is a routing hole for pulling out the wiring 31 of the LED assembly 30 from the case 10. is there.

The light guide plate 20 is a transparent plate that guides light from the LED assembly 30 provided at the end of the light guide plate 20 in order to emit light from the surface of the backlight module, and has high transparency such as acrylic resin and COP. It is composed of resin. In order to uniformly emit the light incident from the side surface of the end portion in the substantially vertical direction from the surface of the backlight module, the surface of the light guide plate 20 has small dot-shaped irregularities formed by surface processing and high light reflectivity. The print dots made of white ink made of resin are arranged at an appropriate density according to the distance from the LED assembly 30 and the like.

The light guide plate 20 of FIG. 1 is provided with a hole 21 for blocking an optical path between each character, number, and hyphen of the application display and the vehicle number, and corresponds to the area divided by the hole 21. When the LED element is broken, the letters and numbers in the corresponding area are darkened so that the failure can be easily visually recognized. A convex portion 12 corresponding to the hole portion 21 is formed on the bottom surface of the case 10, and when the light guide plate 20 is placed on the case 10, the convex portion 12 is fitted into the hole portion 21. The light guide plate 20 can be placed at a predetermined position, and the light guide plate 20 can be fixed in the case 10.

The light diffusing plate 40 not only has a light diffusing function in order to emit light from the light guide plate 20 more uniformly, but is also airtight so that water does not enter the backlight module and damage the LED assembly 30. In order to maintain the above, the outer peripheral portion is joined to the case 10 by an adhesive, a welding process, or the like. The light diffusing function is obtained by mixing a transparent resin with a particulate diffusing material or bubbles having a refractive index different from that of the base resin. Further, the area 42 (the area surrounded by the broken line) corresponding to the place name and the classification number on the surface of the light diffusing plate 40 on the light emitting side is subjected to light-shielding printing for brightness adjustment. Reference numeral 41 denotes a screw hole for integrating the backlight module and the display plate described above.

In the backlight module shown in FIG. 1, a light guide plate 20 and an LED assembly 30 are housed in a case 10, covered with a light diffusing plate 40, and a display plate (not shown) is placed via a dustproof cushion 50. Then, the screws are passed through the screw holes 13 and 41 and the screw holes provided in the display plate to be integrated.

FIG. 3 shows the standard of the chromaticity coordinates of the emission color of the character light type license plate. FIG. 3 is a chromaticity diagram of CIE (1931), and the region shown by the broken line in the diagram is a standard region of the emission color of the character light type license plate, and is a region surrounded by the following four coordinates.
x / y: 0.285 / 0.264, 0.285 / 0.332, 0.440 / 0.382, 0.440 / 0.432

In the backlight module of the present invention, the chromaticity coordinates (x / y) of the emitted color are within the range shown by the broken line in FIG. 3, and x is 0.41 or more and y is 0.40 or more. Located in the area of. The emission color having chromaticity coordinates in the region is pale yellow. The light yellow range is appropriately selected within the above range, but in order to reduce glare and improve the visibility of the display unit, the light-shielding substrate of the display plate is yellow, so that it is a decolorizing system. It is preferable to use a yellowish color having a relatively low color temperature. Among them, the yellow color has higher visibility than the red color, and within the range of the chromaticity coordinate standard, x is 0.41 or more and y is the blackbody radiation trajectory (values of 2000 to 15000 in FIG. 3). The curve in which is described) or more is preferable.

In the present invention, an LED element is used as the most general-purpose light source, and either an organic or inorganic LED element may be used. Further, in the above embodiment, an example using an LED assembly in which LED elements are linearly arranged is shown, but the light source may be a surface light source.

Further, in the present invention, the emission color of the backlight module may be located within the range of the chromaticity coordinates specified in the present invention, and the specific embodiment is not limited. For example, an LED element having an emission color within the chromaticity coordinates may be used, or the emission color of the LED element may be adjusted by an optical filter. When an optical filter is used, it can be used even if the chromaticity coordinates of the emitted color are outside the range of the above standard.

A backlight module having the configuration shown in FIG. 2 composed of the components shown in FIG. 1 was manufactured. For the LED elements of the LED assembly 30, four types of elements with emission colors of white to yellow are used, and the power supply current to the LED assembly 30 is adjusted so that ^{the front brightness of the central portion of the backlight module is 400 cd / m 2.} Then, the chromaticity coordinates of the light emitting color were measured. After the measurement, the existing display plate is attached to prepare a character light type license plate, and the display unit is read from a position 30 m away, which is 10 m farther than the evaluation standard of 20 m in a dark room required for the character light type license plate. Evaluated the ease. The evaluators were 5 people with different visual acuities, and evaluated as "3" when they could be clearly confirmed, "2" when they could be confirmed, and "1" when it was difficult to confirm. Table 1 shows the chromaticity coordinates of the emission color of each backlight module, and Table 2 shows the evaluation results of the character light type license plate.

As shown in Table 2, compared to Comparative Example 1 in which the emission color is white, Comparative Example 2 in which the emission color is a light bulb color has improved visibility, but Examples 1 and Examples have a yellow emission color. Compared with No. 2, there was glare, and the visibility of Examples 1 and 2 having a strong yellowish color was higher.

10: Case, 11: Concave, 12: Convex, 13: Screw hole, 14: Rib, 15: Wiring route hole, 20: Light guide plate, 21: Hole, 30: LED assembly, 31: Wiring, 40: Light Diffusing plate, 41: Screw holes, 42: Light-shielding printing, 50: Dustproof cushion

The present invention is a backlight module for a character light type license plate that uses a light emitting diode element as a light source.
As the light emitting diode element, the chromaticity coordinates (x / y) of the light emitting color are 0.285 / 0.264, 0.285 / 0.332, 0.440 / 0.382, 0 in the CIE chromaticity diagram. Using a light emitting diode element with x of 0.41 or more and y of 0.40 or more within the range surrounded by 4 coordinates of .440 / 0.432.
The chromaticity coordinates (x / y) of the emission color are 0.285 / 0.264, 0.285 / 0.332, 0.440 / 0.382, 0.440 / 0.432 in the CIE chromaticity diagram. in a range surrounded by 4 coordinates, x is from 0.41 or more, y is equal to or 0.40 or more.

Claims (2)

A backlight module for letter-light license plates that uses a light-emitting diode element as a light source.
The chromaticity coordinates (x / y) of the emission color are 0.285 / 0.264, 0.285 / 0.332, 0.440 / 0.382, 0.440 / 0.432 in the CIE chromaticity diagram. A backlight module characterized in that it is located within a range surrounded by the four coordinates of, x is 0.41 or more, and y is 0.40 or more. The backlight module according to claim 1, further comprising a shallow box-shaped case, a light guide plate, and a light diffusing plate, wherein a plurality of the light emitting diode elements are arranged in a row.

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