JPH028404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lighting device that uses a light emitting diode as a light source.

[Conventional technology]

In recent years, with the development of semiconductor technology, high-brightness light-emitting diodes have been developed, and as they have become available at low prices, they are being considered as light sources for various lighting devices, such as automobile brake lights, tail lights, and sign lights. . The main reason for this is that, in addition to the fact that high-brightness products are now available at low prices, unlike regular light bulbs, they do not have a filament, so they have a semi-permanent lifespan. There is no need for careful design,
It has many excellent features, such as fewer restrictions on the light fixture itself and its mounting location, the light fixture can be made thinner and easier to install, it generates significantly less heat than light bulbs and has good luminous efficiency, and it consumes less electricity. This can be said to indicate the direction of future lighting equipment. FIG. 4 shows a conventional example of this type of lamp, in which 1 is a lamp body, 2 is a surface lens that closes the front opening of the lamp body 1, and 3 is a light-emitting diode 4 mounted on the surface of the lamp body. 1 are convex lenses formed densely on the inner surface of the front lens 2, and these convex lenses 5 correspond to each of the light emitting diodes 4. The light 6 is focused and diffused.

[Problem that the invention seeks to solve]

However, in such a lamp, since a light emitting diode 4 is disposed for each convex lens 5, a large number of light emitting diodes 4 are required, resulting in an inconvenience that the price of the lamp itself becomes high. Furthermore, even if a large number of light emitting diodes 4 are used, each light emitting diode 4 is regarded as a point light source, so the surface lens 2 is connected to each light emitting diode 4.
The area around the optical axis was bright, and the further away from the optical axis, the darker it became, which caused problems in terms of uniform illumination. Furthermore, since the convex lens 5 diffuses the light 6 from the light emitting diode 4 in all directions, there is a problem in that it is not possible to obtain a long light distribution characteristic in the width direction of the lamp, which is required when the lamp is used as a vehicle lamp. Therefore, the present invention has been made in view of the above-mentioned problems.
Another object of the present invention is to provide a lighting device that can obtain a wide range of diffused light in the width direction of the lamp without changing the size of the lamp itself, and can obtain horizontal light distribution characteristics.

[Means for solving problems]

In order to achieve the above object, the present invention provides a lighting device using a large number of light emitting diodes as a light source, in which a lens installed in front of each light emitting diode converts light from each diode into parallel light beams approximately parallel to the optical axis. A large number of Fresnel lenses are provided, and a diffusion prism is provided between the Fresnel lenses to diffuse light from the light emitting diode in the width direction.

[Effect]

In the present invention, each Fresnel lens converts the light from the corresponding light emitting diode into parallel light rays substantially parallel to the optical axis. The diffusion prism diffuses the light from the light emitting diode in the width direction of the lamp.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a front view of essential parts showing an embodiment of a lighting device according to the present invention, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line -- in FIG. Components in the figure that are the same as those in FIG. 4 are designated by the same reference numerals, and their explanations will be omitted. In these figures, on the inner surface of the front lens 2,
A plurality of Fresnel lenses 11 are formed for each light emitting diode 4, respectively.

The Fresnel lens 11 has the function of guiding the light emitted from the corresponding light emitting diode 4 forward as parallel light rays 12 substantially parallel to the optical axis, and has a plurality of concentric protrusions with a triangular cross-sectional shape. The angle of inclination of the inner slope of each protrusion is set such that the protrusion farther from the center gradually becomes smaller. And each Fresnel lens 11
The outermost protruding stripes are in contact with the outermost protruding stripes of the upper, lower, left and right Fresnel lenses 11.

A Fresnel lens 1 is attached to the inner surface of the front lens 2.
A diffusion prism 13 is formed in a portion other than where 1 is formed to diffuse the light emitted from each light emitting diode 4 in the width direction (horizontal direction) of the lamp. This diffusion prism 13 is composed of a plurality of longitudinally long protrusions arranged in parallel in the width direction of the front lens 2, and each protrusion has a cross-sectional shape as shown in FIG. It forms an approximately isosceles triangle.

Reference numeral 14 denotes a flexible printed circuit board on which the light emitting diode 4 is mounted, and a diode holding member 15 is arranged in parallel and close to the flexible printed circuit board in front of the flexible printed circuit board. The diode holding member 15 is formed with an insertion hole 16 into which each light emitting diode 4 is inserted, thereby stably holding the light emitting diode 4 and preventing it from falling down.

Thus, according to the lighting device having such a configuration, the amount of light toward the front of the lamp is not impaired,
A horizontal rectangular light distribution characteristic can be obtained.

That is, when the light emitted from each light emitting diode 4 passes through the front lens 2, the light 17 directed toward the Fresnel lens 11 is transformed by the Fresnel lens 11 into parallel light rays 18 substantially parallel to the optical axis, as shown in FIG. This parallel light ray 18 passes through the front lens 2 and exits to the outside. Therefore, a sufficient amount of light can be ensured in the forward direction. In this case, each Fresnel lens 1
1 covers a wider illumination range than the convex lens 5 shown in FIG. 4, so the number of light emitting diodes 4 can be significantly reduced compared to the conventional device. Further, the Fresnel lens 11 converts the light 17 from the light emitting diode 4 into parallel light rays 18, converting the light emitting diode 4 from a point light source to a surface light source.

On the other hand, among the light emitted from each light emitting diode 4,
The light 19 directed toward the diffusing prism 13 is diffused in the width direction of the front lens 2 by the diffusing prism 13,
This results in a light distribution characteristic that is short in the vertical direction and long in the horizontal direction. Therefore, it is suitable for a vehicle lamp that requires horizontal rectangular light distribution characteristics.

In the above embodiment, one light emitting diode 4 is provided for each Fresnel lens 11, but if there is a risk that the overall brightness may decrease, several light emitting diodes 4 may be provided for each Fresnel lens 11. They may be arranged closely around the optical axis to ensure the necessary amount of light.

Further, in the above embodiment, the Fresnel lens 11 and the diffusion prism 13 are formed on the inner peripheral surface of the front lens 2, but the invention is not limited to this, and an inner lens is formed between the front lens 2 and the light emitting diode 4. It goes without saying that the Fresnel lens 11 and the diffusion prism 13 may be formed thereon.

〔Effect of the invention〕

As explained above, the lighting device according to the present invention includes:
In the lens placed in front of each light emitting diode,
A Fresnel lens that converts the light from the diode into a parallel beam almost parallel to the optical axis and a diffusion prism that diffuses the light from the light emitting diode in the width direction are provided, so the amount of light in the front direction can be increased, and the device It is possible to obtain long light distribution characteristics in the width direction without making the device itself horizontally long. In addition, a light emitting diode used as a point light source can be converted to a surface light source, thus enabling uniform illumination, and since it is only necessary to provide a light emitting diode for each Fresnel lens, the number of diodes can be reduced. It is possible to provide an inexpensive lighting device. Furthermore, if the number of diodes is small, the amount of heat generated is also small, which has a very large effect.

[Brief explanation of drawings]

FIG. 1 is a front view of main parts showing an embodiment of the present invention;
Figure 2 is a sectional view taken along the - line in Figure 1, and Figure 3 is a cross-sectional view of Figure 1.
FIG. 4 is a cross-sectional view of a main part showing an example of a conventional device. 1...Lamp body, 2...Surface lens, 3...
Substrate, 4... Light emitting diode, 5... Convex lens,
11... Fresnel lens, 13... Diffusion prism.

Claims (1)

[Claims] 1. In a lighting device that uses a large number of light emitting diodes as a light source, a Fresnel lens is provided in the lens installed in front of each of the light emitting diodes to convert the light from each light emitting diode into a parallel beam substantially parallel to the optical axis, and a Fresnel lens is provided. A lighting device characterized in that a diffusion prism is provided between the light emitting diodes to diffuse light from the light emitting diodes in the width direction.