Flash unit, camera device, and mobile terminal

A flash unit having a light emitting element, and a light condensing plate. The light condensing plate is provided with a surface on which a dimmed light-dispersing print is disposed near the light emitting element for equalizing intensity of the light emitted from the light emitting element. The other side of the light condensing plate contains a convexo-concave surface for condensing the light emitted from the light emitting element. The present invention provides a flash unit, a camera device, and a mobile terminal having a small dimension so as to provide a flash unit having an increased flash light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all rights of priority to Japanese Patent Application No. 2003-063594 filed on Mar. 10, 2003, (pending).

BACKGROUND OF THE INVENTION

The present invention relates to a flash unit which is used for a camera device, or a mobile terminal.

Conventionally, as shown inFIGS. 8A and 8B, a flash for a camera module comprises a flash tube24which serves as a light source, a reflecting mirror23is disposed behind the flash tube to forwardly reflect the light emitted from the flash tube, a light condensing plate22provided with a convexo-concave wavy surface on the flash tube for condensing the light emitted from the flash tube and the reflecting mirror, and a casing21to contain the above elements (see Japanese Unexamined Patent Application, First Publication No. Hei 4-34423, pages 2 to 4, and FIG. 1). Another typical embodiment is shown inFIGS. 9A and 9B. A LED (light emitting diode)26which serves as a light source, a base board27for mounting an LED thereon, and a plate28to which a dense white dispersion print is placed on the surface facing the LED (or a plate which is formed by a lactescent resin member) disposed such that the LED and the base board on which the LED is mounted cannot be viewed from the outside.

However, in the flash for the camera module shown inFIGS. 8A and 8B, there has been a problem that an entire structure of the flash is large or thick because the flash tube24itself which is used for the light source is a large member.

In the flash for the camera module which is built in the mobile phone device as shown inFIGS. 9A and 9B, it is possible to use a smaller flash by using the LED26for a light source. However, there has been a problem in that it is not possible to have a sufficient amount of flash light. This disadvantage occurs because in order to prevent the flash from being seen, plate28is provided and does not allow the LED to provide a sufficient light amount.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a flash unit, a camera device, and a mobile terminal which can provide an increased amount of flash light. Another object of the present invention is to provide a smaller sized flash.

In order to solve the above problems, the flash unit comprises a light emitting element and a light condensing plate. The light condensing plate is provided with a light dispersing surface on the side of the light condensing plate facing the light emitting element to equalize the intensity of the light emitted from the light emitting element. A convexo-concave surface is on other side of the light condensing plate for condensing the light emitted from the light emitting element. Also, it is preferable that the flash unit of the present invention further comprises a guide disposed between the light emitting element and the light condensing plate for preventing the light emitted from dispersing.

The present invention also provides a camera device comprising a camera module for capturing an image, a light emitting element, and a light condensing plate. The light condensing plate is provided with a light condensing surface having a light dispersing surface disposed on the near side of the light condensing plate facing the light emitting element to equalize the light which is emitted from the light emitting element and a convexo-concave surface on other side of the light condensing plate for condensing the light emitted from the light emitting element. Also, it is preferable that the light condensing plate is unitarily formed with a lens of the camera module or a lens cover of the camera module.

Also, it is preferable that the camera device further comprises a guide disposed between the light emitting element and the light condensing plate for preventing the light from dispersing. Furthermore, it is preferable that a thickest dimension T of the plate between the light condensing plate and which forms the lens or lens cover satisfies a relationship T≦1.0 mm.

Furthermore, it is preferable that the light emitting element is disposed lower than the lens of the camera module with respect to a surface of a board to which the camera module is attached.

A mobile terminal of the present invention comprises a light emitting element and a light condensing plate. In this embodiment, it is preferable that the light condensing plate is provided with a light condensing surface such that the light condensing plate has a light dispersing surface on a near side of the light emitting element so as to equalize the light which is emitted from the light emitting element and a convexo-concave surface on other side of the light condensing plate for condensing the light emitted from the light emitting element. Also, the mobile terminal further comprises a guide which is disposed between the light emitting element and the light condensing plate for preventing the light from dispersing.

The mobile terminal according to the present invention further comprises a camera module for capturing an image wherein the light condensing plate is unitarily formed with a lens of the camera module or a lens cover of the camera module.

Also, it is preferable that a thickest dimension T of the plate between an area which forms the light condensing plate and an area which forms the lens or a lens cover satisfies the relationship T≦1.0 mm. Furthermore, it is preferable that the light emitting element is disposed lower than the lens of the camera module with reference to a surface of a board to which the camera module is attached.

DETAILED DESCRIPTION

A flash unit and a camera device according to embodiments of the present invention are explained in detail below with reference toFIGS. 1 to 7C.

As shown inFIG. 1, a flash unit according to a first embodiment of the present invention comprises a base board1, an LED2, a light condensing plate3, and a casing4.

The base board1serves as a circuit board for mounting the LED2thereon. For the base board1, various members such as flexible printed circuit board (hereinafter called an FPC), phenolic paper, or a glass texture epoxy can be used. Also, the base board1is fixed closely on the surface of the casing4. The LED2is a luminescent semiconductor element such that the LED2emits a light if a voltage in a positive direction is charged thereto.

The light condensing plate3comprises a member31which is formed by molding a transparent resin as shown inFIGS. 3A and 3B. A dimmed print surface32is formed on a surface of the light condensing plate3so as to equalize light emitted from the light source. The other side of the light condensing plate3comprises a convexo-concave shape to condense the light emitted from the light source. As long as the convexo-concave surface condenses the light, it does not matter if the convexo-concave surface is a wavy surface formed by combining a wavy surface and a saw-shape surface or if the combining surfaces have predetermined acute angles.

In the present embodiment, the convexo-concave surface is formed without acute angles, so that a human finger would not be injured while contacting the surface of the convexo-concave surface. Here, the dimmed print surface32is disposed near the LED2to prevent the printed surface from being deteriorated by contact with human fingers etc. Also, if a dimmed print surface is disposed on the convexo-concave surface, the area which disperses the light increases; thus, the amount of the light which is reflected also increases. Also, the convexo-concave member and the surface of the LED2are not parallel; thus, the light may be reflected more frequently in the convexo-concave surface. Therefore, the amount of light which transmits to an object may decrease. The convexo-concave surface is formed so as not to have an acute edge. The casing4serves for containing various members which form the above flash unit. The casing4is formed with an aperture into which the light condensing plate3fits. Here, it is preferable that the casing4should be formed by a resin member or a metal member because the casing4should be as heavy as possible.

In the flash unit according to the present embodiment, the light condensing plate3is disposed such that the dimmed print surface of the light condensing plate3faces the LED2mounted on the base board1. The light which is emitted from the LED2is equalized on the dimmed print surface and is further condensed by the convexo-concave surface; thus, the light is emitted toward the object to be taken.

Therefore, in the present embodiment, it is possible to obtain an increased amount of light because the light which is emitted from the light source is prevented from dispersing on the convexo-concave surface formed on the dimmed print surface of the light condensing surface3and the convexo-concave surface formed on another surface of the light condensing surface3. Also, the base board on which the LED2is mounted can hardly be viewed from the outside; thus, it is possible to form the dispersion print under dimmer condition.

In another embodiment of the present invention, a guide5is disposed between the LED2and the light condensing surface3as shown inFIG. 2. The guide5is formed by a transparent resin having a frustum shape. A plating treatment is performed on an outside of the guide such that an inner surface of the guide5serves as a mirror. The aperture of the guide5having an approximate frustum shape near the LED2is approximately the same as an area for emitting a light from the LED2. The guide5is disposed near the LED2or the guide5contacts the LED2. On the other hand, an aperture near the light condensing plate3is approximately the same as the light condensing plate3so as to be fixed to a supporting member of the light condensing plate3.

The operation of the present embodiment are explained with reference toFIGS. 4A and 4B.

As shown inFIG. 4A, part of the dispersing light is emitted from the LED2serves as a light source reaches to the light condensing plate3such that the emitted light condition should not change. The rest of the light reaches the light condensing plate3while the inner surface of the guide5serves as a mirror to reflect and deflect the rest of the light. The rest of the light is reflected also on the dimmed print surface of the light condensing plate3. The light which returns to the LED2is also reflected on the inner surface of the guide5so as to be transmitted to the light condensing plate3again.FIGS. 5A and 5Bshow a cross section along line B-B′ in which a flash unit is mounted on a mobile terminal. As shown inFIG. 5A, the guide5is disposed near two LEDs2which serve as light sources. Alternatively, the guide5may be disposed so as to contact the LEDs2. The apertures of the LEDs2on the guide5are approximately the same as the area for emitting light on the LEDs2; thus, there is very little light leaking from near the light emitting surface of the LEDs2. Therefore, as shown inFIG. 2, it is not necessary to contain the flash unit in the casing4. Therefore, for example, it is possible to use a casing of the mobile terminal for containing the flash unit compatibly.

As shown inFIG. 4B, the light which reaches the light condensing plate3is equalized on the dimmed print surface. The light which is incident is diffracted by the convexo-concave plane disposed on an opposite side of the light condensing plate3. Thus, the light is prevented from dispersing entirely and is emitted toward the object to be taken. Therefore, in the present embodiment, it is possible to further restrict the dispersion of the light emitted from the light source by the guide5to obtain an increased amount of flash light. Also, the aperture on the guide5near the LEDs2is approximately the same as the area for emitting the light from the LEDs2. Also, the guide5is disposed near the LEDs2. Alternatively, the guide5is disposed such that it comes in contact with the LEDs2. Therefore, the base board on which the LEDs2are mounted can barely be viewed from the outside.

Next, a camera device in which the above flash unit and a camera module7are disposed is explained.

As shown inFIGS. 6A-6C, the cameral module7and the flash unit are disposed so as to be near each other in the camera device according to the present invention. In the present embodiment, a distance between center of the camera module7and the center of the flash unit is 6.35 mm (seeFIG. 6A). Also, a light source in the flash unit is disposed so as to be shifted slightly downwardly with reference to the center of the camera module7. In the present embodiment, a vertical distance between a center of the camera module7and the center of the flash unit is 2 mm (seeFIG. 6A).

InFIG. 6B, a plate which is built in a structure shown inFIG. 6Ais shown. Here, the plate is a decorated board which is viewed by a user of the camera device. As shown in the drawing, a lens cover6of the camera module7and the light condensing plate3are formed by the same transparent resin decorated board. Here, the thickness of the decorated board between an area of the light condensing plate3and an area of the lens cover6is determined according to factors such as molding conditions and an influence of the light which is emitted from the flash unit to reach to the camera module7.FIG. 6Cshows a structure in which the camera module7and the LEDs2are disposed on the base board1. As shown in the drawing, the light-emitting surfaces of the LEDs2are disposed so as to be lower than the lens surface of the camera module7with reference to a surface of the base board1; thus, the flash light is hardly disposed on the lens of the camera module7.

In order to determine the thickest dimension of the decorated board between the light condensing plate3and the lens cover6, experiments are performed so as to observe how an image may be influenced by the light emitted from the flash unit.

For the above method, the camera module7and the light condensing plate3of the flash unit are sealed from the light by tightly placing a sponge member or a black textile around the camera module7and the light condensing plate3of the flash unit to absorb the light. Consequently, an image which is taken with a flashed light and an image which is taken under a complete darkness condition without a flash light are compared.

The above experiment is performed to determine if the light emitted from the flash unit does not reach to the camera module7and if the images are the same with regardless to whether or not the flash light is emitted. Evaluations are made of four boards below. As far as an optical transmission is concerned, it is generally understood that acrylic member has superior optical transmission to a polycarbonate member; thus, more light reaches to the camera module7in a case of the acrylic member.

1) A polycarbonate decorated board having 0.8 mm thickness

2) An acrylic decorated board having 1.0 mm thickness

3) An acrylic decorated board having 2.0 mm thickness

4) An acrylic decorated board having 3.0 mm thickness

According to results of the above experiments andFIGS. 7A to 7C, it is understood as follows.FIG. 7Cshows the thickness of the decorated board being 3.0 mm and the image is entirely cloudy. In a case ofFIG. 7Bthe thickness of the decorated board is 2.0 mm and a cloudy image can be observed from the center of the image to the upper region of the image. In a case ofFIG. 7Athe thickness of the decorated board is 1.0 mm and a cloudy image cannot be observed; therefore, it can be understood that the images are the same, regardless to whether or not the flash light is emitted. The same result is obtained in a case in which a polycarbonate decorated board having 0.8 mm thickness, which is not shown in the drawing is used.

According to the above experiments, it is understood that the less light emitted from the flash unit reaches to the camera module7as long as the thickness of the light condensing plate3is as thin as possible. The light which is incident to the light condensing plate3is reflected more frequently as long as the thickness of the light condensing plate3is as thin as possible; thus, the light is attenuated accordingly. As a result, less light reaches the camera module7. Therefore, it should be understood that an optimal thickness T of the light condensing plate3is T≦1.0 mm when an acrylic member is used and the above result of the experiments and the molding condition for the light condensing plate3are taken into consideration.

The strength of the decorated board depends on a material to be used. More importantly, it should be understood that the decorated board may be rigid, as long as the thickness of the decorated board is approximately 0.8 mm or greater.

According to the present embodiment, the camera module and the flash unit are disposed so as to be near each other; therefore, it is possible for the camera device to be smaller in size. In addition, it is possible to form the lens cover6of the camera module and the light condensing plate3by a decorated board unitarily. If the camera module and the flash unit are disposed near each other, there is a problem in that a light emitted from the flash unit reaches to the camera module. However, as shown in the above results, the essential function of the light condensing plate3will not be deteriorated as long as the thickness of the decorated board is in an appropriate range; thus, it is possible to solve such a problem.

The embodiments of the present invention are described above with reference to the drawings. It should be apparently understood that the invention can be embodied in a wide variety of forms including various alternative design for the disclosed embodiments. Consequently, the specific structural and functional details disclosed herein are merely representative and do not limit the scope of the invention. For example, in the above embodiment, explanations are made for a case in which the light-condensing plate and the lens cover of the camera module are formed unitarily by a plate. However, more importantly, it may be acceptable if the light-condensing plate and the lens of the camera module are formed unitarily by a plate.

Also, in the above embodiments, the dimmed print is placed on a surface of the light-condensing plate such that a color for the dimmed print is not limited. However, more importantly, it is possible to use any color as long as it is a dimmed color such as a dimmed yellow, or a dimmed blue other than a dimmed white.

In the present embodiment, a light condensing plate is provided with a dimmed light-dispersing print is disposed thereon near the light-emitting element for equalizing intensity of a light. The other side of the light condensing plate comprises and a convexo-concave surface on other side of the light condensing plate for condensing the light which is emitted from the light emitting element. Therefore, the dispersing light which is emitted from the light-emitting element is equalized on the print surface on the light-condensing plate. Also, the equalized light is condensed efficiently by the convexo-concave surface which is disposed in an opposite region. Thus, a sufficient amount of the light is emitted toward an object to be taken.

Also, a guide is provided for preventing a light from dispersing is disposed between the light-emitting element and the light-condensing plate. Therefore, the dispersing light from the light-emitting element is prevented from dispersing by the guide. Furthermore, the light which passes through the guide is equalized on a print surface on the light-condensing plate so as to be condensed by the convexo-concave surface efficiently; thus, a sufficient amount of light is emitted toward an object to be taken.

Also, the light-condensing plate and the lens of the camera module are disposed on a thin plate. Alternatively, the light-condensing plate and the lens cover of the camera module are disposed on a thin plate. By doing this, the camera module and the flash unit are disposed so as to be near each other. Therefore, it is possible to form an entire camera device in a thin and small dimension. Here, the thickness of the light-condensing plate is in a constant range; thus, it is possible to form an entire camera device in a thin and small dimension. Furthermore, the light-condensing plate is formed in thin manner, the light which is incident to the light-condensing plate is reflected more frequently. Therefore, it is possible to prevent the light from being attenuated and reached in the camera device.

Also, the light-emitting surface of the light-emitting element is disposed so as to be lower than the lens surface of the camera module with reference to a surface of the base board on which the camera module is mounted. Therefore, it is possible to prevent the light which is emitted from the light-emitted element from reaching to the camera module by an optical dispersion.

Also, a small and thin flash unit or a small and thin camera device which can obtain a sufficient amount of flash light is disposed in a mobile terminal; therefore, it is possible to realize a desirable portability with a superior image quality.

As explained above, according to the present invention, it is possible to form a flash unit and a camera device in a small and thin dimension. Therefore, there is an effect in that it is possible to propose a flash unit, a camera device, and a portable terminal which are required to have a superior portability.