Camera flash lens and portable device including the same

A camera flash lens for a plurality of light emitting diodes (LEDs) mounted on a board and serving as a light source of a camera flash, includes a plurality of annular lenses corresponding to the plurality of LEDs, respectively. The plurality of annular lenses each include an edge portion extending toward the board to reflect and collect light emitted from the edge of a corresponding LED of the plurality of LEDs, and a central portion having an inner surface with a Fresnel shape or a curved shape to collect light emitted from the top of the corresponding LED.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No. 10-2009-0001977 filed on Jan. 9, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a camera flash lens and a portable device including the same, and more particularly, to a camera flash lens which can efficiently concentrate light, emitted from a plurality of light emitting diodes (LEDs) serving as a light source of a camera flash, within the angle of view of a camera, and a portable device including the same.

2. Description of the Related Art

Recently, increasing numbers of portable devices have been provided with camera features. These portable devices may include flashes to provide a sufficient amount of light for low-light photography.

In this regard, a white light emitting diode (LED) is increasingly being used as a light source of a camera flash.

For example, a camera flash, employing an LED as its light source, may utilize an exterior cover and a reflector provided with a reflective surface having a high reflectance level and designed to adjust the angle of radiation emitted by the LED within the angle of view of a camera. Alternatively, such a camera flash may utilize a flash lens, a mechanism that fixes the flash lens, and an LED package in an integral package.

However, the above methods may entail complicated structures. Also, it is not easy to manufacture a camera flash employing a separate component to allow the angle of radiation of an LED to coincide with the angle of view of a camera.

For this reason, in the case that an LED is used as a light source of a camera flash, the need arises to develop a flash lens that allows light from the LED to be emitted within the angle of view of a camera with a simple structure. In particular, a flash lens needs to narrow the angle of radiation of an LED, which ranges from 120° to 130°, to the angle of view of a camera (56° in width and 48° in length), so that light is emitted within the angle of view of the camera.

Even in the case of utilizing two or more LEDs to increase the intensity of illumination, the need is increasing for flash lenses allowing light to be effectively emitted within the angle of view of cameras.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a camera flash lens, which can efficiently concentrate light, emitted from a plurality of light emitting diodes (LEDs) serving as a light source of a camera flash, within the angle of view of a camera, and a portable device including the same.

According to an aspect of the present invention, there is provided a camera flash lens, for a plurality of light emitting diodes (LEDs) mounted on a board and serving as a light source of a camera flash, including a plurality of annular lenses corresponding to the plurality of LEDs, respectively, and each including: an edge portion extending toward the board to reflect and collect light emitted from an edge of a corresponding LED of the plurality of LEDs; and a central portion having an inner surface with a Fresnel shape or a curved shape to collect light emitted from a top of the corresponding LED.

The edge portions of the camera flash lens may contact each other.

The edge portions of the camera flash lens may be conjoined, forming a boundary therebetween. The boundary may extend toward the board.

The edge portions of the camera flash lens may be conjoined without a boundary therebetween.

The central portion of the camera flash lens may correspond to the center of the corresponding LED.

The edge portion of the camera flash lens may have an outer circumference being at an acute angle to an optical axial direction from the board toward the annular lens.

The camera flash lens may be formed of an acrylic material.

According to another aspect of the present invention, there is provided a portable device including: a plurality of light emitting diodes (LEDs) provided as a light source; a board on which the plurality of LEDs are mounted; and a plurality of annular lenses corresponding to the plurality of LEDs, respectively, the plurality of annular lenses each including an edge portion extending toward the board to reflect and collect light emitted from an edge of a corresponding LED of the plurality of LEDs; and a central portion having an inner surface with a Fresnel shape or a curved shape to collect light emitted from a top of the corresponding LED.

The edge portions of the portable device may contact each other.

The edge portions of the portable device may be conjoined, forming a boundary therebetween. The boundary may extend toward the board.

The edge portions of the portable device may be conjoined without a boundary therebetween.

The central portion of the portable device may correspond to the center of the corresponding LED.

The edge portion of the portable device may have an outer circumference being at an acute angle to an optical axis from the board toward the annular lens.

The camera flash lens of the portable device may be formed of an acrylic material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1is a schematic perspective view of a camera flash lens installed in a portable device according to an exemplary embodiment of the present invention.

InFIG. 1, a mobile communication terminal1is illustrated as a portable device according to the present invention. A reception part4for the reception of a camera flash lens10is formed in one surface of a body2of the mobile communication terminal1.

The camera flash lens10is installed in the body2in a direction oriented toward an object so as to allow for convenient image capturing. That is, the camera flash lens10may be placed opposite to a display unit (not shown).

A plurality of light emitting diodes (LEDs)20are mounted on a board40inside the body2to serve as a light source of a camera flash. In this embodiment, two mounted LEDs20are illustrated. These LEDs20are arranged in a row on the board40, and have a wider angle of radiation (120° to 130°) than the angle of view of general cameras (56° in width and 48° in length).

Annular lenses13and15are conjoined and correspond to the LEDs20, respectively. The annular lenses13and15serve to collect light emitted from the LEDs20so that the angle of radiation of the LEDs20corresponds to the angle of view of a camera.

Hereinafter, the camera flash lens10including the annular lenses13and15will be described in more detail.

FIG. 2is a schematic perspective view illustrating LEDs mounted on a board, and a camera flash lens collecting light emitted from the LEDs, according to an exemplary embodiment of the present invention.FIG. 3is a cross-sectional view of the LEDs and the camera flash lens depicted inFIG. 2, showing the camera flash lens having an inner surface in the shape of a Fresnel lens (hereinafter, referred to as ‘Fresnel shape’) according to an exemplary embodiment of the present invention.FIG. 4is a cross-sectional view of the LEDs and the camera flash lens depicted inFIG. 2, showing the camera flash lens having a curved inner surface according to another exemplary embodiment of the present invention.

Referring toFIGS. 2 through 4, the camera flash lens,10includes the annular lenses13and15that are conjoined. Each of the annular lenses13and15includes an edge portion12and a central portion14.

The camera flash lens10collects light emitted from the LEDs20mounted on the board40and serving as a light source of a camera flash. A plurality of LEDs20are provided on the board40in order to ensure sufficient intensity of illumination. Therefore, the number of the annular lenses13and15, collecting light emitted from the LEDs20, needs to correspond to the number of LEDs20.

The LEDs20, mounted on the board40, are spaced apart from each other at a distance (d) that allows a boundary16between the conjoined annular lenses13and15to be placed between the LEDs20. The extent to which the annular lenses13and15are conjoined varies according to the distance (d) between the LEDs20on the board40.

Each of the LEDs20includes a thin LED chip disposed on a substrate22, and a light-transmissive material24surrounding the LED chip. The LED chip is covered with the light-transmissive material24. The light-transmissive material24contains phosphorous bodies to convert the wavelength of a portion of light emitted from the LED chip, thereby producing white light.

The edge portion12extends toward the board40and reflects and collects light emitted from the rough edge of the corresponding LED20. The bottom of the edge portion12may be at a predetermined distance from the board40on which the LED20is mounted.

In particular, the bottom of the edge12may be at a distance of about 0.8 mm above the board40, and this distance may be adjusted to be either higher or lower in due consideration of productivity and performance.

The shorter the distance is, the more effectively light from the LEDs20can be collected. However, this may adversely affect the manufacturing and assembling processes. In contrast, the greater the distance is, the easier the manufacturing process becomes but the less light from the LED20is collected.

An outer circumference18of the edge portion12may be inclined at an acute angle to the optical axial direction (O) from the board40toward the camera flash lens10. By constructing the outer circumference18in the above manner, light can be emitted from the LED20outwardly within the angle of view of a camera.

The central portion14is provided as a recess inside the edge portion12. The inner surface of the recess has a Fresnel shape, or a curved shape14′ depicted inFIG. 4.

The central portion14having the inner surface of the curved shape14′ may have its convex center oriented toward the corresponding LED20to ensure the effective emission of light from the LED20.

The recess may have a depth of about 1 mm and be spaced apart from the top of the LED20at a distance of about 0.35 mm. In particular, the depth of the recess is closely associated with the formation of the Fresnel shape.

If the recess has a depth exceeding 1 mm, a sawtooth portion of the Fresnel shape needs to protrude more for lens performance. If the recess has a depth of less than 1 mm, the sawtooth portion of the Fresnel shape needs to protrude less.

The further the sawtooth portion of the Fresnel shape protrudes, the more difficult the manufacturing process becomes. In contrast, the less the sawtooth portion of the Fresnel shape protrudes, the more the manufacturing process is facilitated. That is, the degree of difficulty of the manufacturing process is determined by the extent to which the sawtooth portion of the Fresnel shape protrudes. Therefore, the depth of the recess needs to be determined regarding the extent to which the sawtooth portion protrudes.

The Fresnel shape allows for the effective radiation of light from the LED20. The center (c) of the central portion14corresponds to the center (c′) of the LED20.

The camera flash lens10needs to be formed of a material that can be processed and molded easily since it is subject to processing in regard to its thicknesses, recess and Fresnel shape. The camera flash lens10may utilize a plastic material, and an acrylic material with high workability, such as acrylic or poly methyl methacrylate (PMMA) may be used.

FIG. 5is a schematic perspective view illustrating LEDs mounted on a board, and a camera flash lens collecting light emitted from the LEDs, according to another exemplary embodiment of the present invention.FIG. 6is a cross-sectional view of the LEDs and the camera flash lens depicted inFIG. 5.

Referring toFIGS. 5 and 6, the camera flash lens10, according to another exemplary embodiment of the present invention, includes the annular lenses13and15that are conjoined. The annular lenses13and15each include the edge portion12and the central portion14.

The annular lenses13and15are conjoined more so than they are in the embodiments ofFIGS. 2 through 4, thus having no boundary16that divides the central portions14of the annular lenses13and15. The central portions14of the conjoined annular lenses13and15have no distinctive boundary therebetween.

The extent to which the edge portions12are conjoined may be determined within the range that does not cause the two annular lenses13and15to be combined fully and thus form a circle.

According to this embodiment, the central portion14having a Fresnel shape is illustrated, but the central portion14may also have a curved shape.

According to this embodiment, the distance (d′) between the LEDs20mounted on the board40is shorter than the distance (d) in the embodiments ofFIGS. 2 through 4. Here, the minimum distance (d′) between the LEDs20mounted on the board40may be set to the distance when the LEDs20contact each other.

Other elements of this embodiment are substantially identical to those in the embodiments ofFIGS. 2 through 4, and thus a detailed description thereof will be omitted.

In the camera flash lens and the portable device including the same according to the present invention, the plurality of LEDs and the flash lens that can reduce the angle of radiation of the LEDs with a simple structure are provided, thereby emitting light with high intensity within the angle of view of a camera.

As set forth above, according to exemplary embodiments of the invention, two or more LEDs and a flash lens having a simple structure to reduce the angle of radiation of the LEDs are provided in the camera flash lens and the portable device including the same. Accordingly, light with high intensity can be emitted over the entire angular field of view of a camera.