Still Camera

1. Field of the Invention

This invention relates to a still camera that is provided with a light emitting device for projecting an indication light toward an object when a self-timer is activated, and more particularly to a still camera, in which a person, acting a an object, can confirm the picture taking area of a taking lens because of the provision of this light emitting device for indicating actuation of the self-timer.

2. Prior Art

Many conventional cameras, which have been heretofore used, have a self-timer function for delaying the interval time from when a shutter button is depressed to when the shutter is released. Also, many still cameras are equipped with a light emitting device that includes a light source, such as a light emitting diode (hereinafter simply referred to as "LED"), which is adapted to indicate the activation of the self-timer mode of operation.

In general, a light emitting device for indicating the actuation of the self-timer comprises a LED contained in a body, and a cover (e.g., transparent cover, diffusion plate, lens, or Fresnel lens) disposed in front of the LED.

The relationship between the taking area of a taking lens and the light projection area of a light emitting device for indicating actuation of the self-timer is variable. As shown in FIG. 5, for example, there is shown one in which the light projection area of a light emitting device 1 for indicating the actuation of the self-timer is large as compared with the taking area of a taking lens 2. In another example (not shown), the light projection area of the light emitting device is small as compared with the taking area of the lens. In still another example, the indicating light does not reach the other side because the light is blocked with a lens barrel.

When taking a picture in an ordinary manner, it is not difficult to include the object in the taking area because the photographer can actuate the shutter while visually confirming the object through the finder.

On the other hand, when a self-timer is used, the circumstance is different because the photographer is being included in the picture that is to be taken. In this case, the photographer conducts a framing through the finder, actuates the self-timer, pushes the shutter button and thereafter, quickly goes to the other persons in front of the camera. Therefore, when the persons move after the framing is completed, there is no way for the photographer to know whether the moved persons are still in the taking area of the taking lens at the moment when the shutter is released.

When many persons are to be taken as one group, the photographer often stands or sits in the extreme side of the group. In this case, it is very difficult for the photographer to know whether he is surely in the taking area of the taking lens.

The present invention has been developed to overcome the above-mentioned inconveniences. It is therefore an object of the present invention to provide a still camera, in which a person standing in front of the camera can confirm whether he is within the taking area of the taking lens.

The present invention has been accomplished by recognizing that a conventional light emitting device for indicating the actuation of a self-timer has heretofore been used only for indicating the self-timer actuation. In order to achieve the above-mentioned object, according to the present invention, the light projection area of the light emitting device for indicating the self-timer actuation is designed to be generally coincident with the taking area of a taking lens.

By virtue of the foregoing arrangement, a person can easily find out whether he is within the taking area of the taking lens by paying attention to whether the indication light can be seen by him.

FIGS. 1 through 4 illustrate embodiments of a still camera according to the present invention, wherein;

FIG. 1 is a schematic view showing a concrete example of FIG. 4;

FIG. 2 is a front view of a still camera having a light emitting device for indicating a taking area of a taking lens;

FIG. 3(a) is a schematic view showing the constitution of the light emitting device used in the camera of FIG. 2;

FIG. 3(b) is a schematic view showing the optical arrangement of the taking lens used on the camera of FIG. 2 and the light emitting device for indicating the actuation of the self-timer according to the first embodiment of the present invention; and

FIG.; 4 is a schematic view similar to FIG. 3(b), showing a second embodiment of the present invention;

FIG. 5 is a schematic view showing the optical arrangement of a taking lens and a light emitting device for indicating actuation in a conventional still camera.

The present invention will be described hereunder with reference to the accompanying drawings.

Referring to FIGS. 2 through 4, a general principle will be described, and then, an example, shown in FIG. 1, will be described.

A still camera 10 comprises a lens shutter camera, as shown in FIG. 2. The still camera 10 is provided with a taking lens 20 that is located proximate the center of its front body. A light emitting device 30, for indicating the actuation of a self-timer is adapted to project an indication light towards an object to be photographed when the self-timer is actuated. The light emitting device 30 is disposed in a position on the front of the camera body (see FIG. 2) that is spaced apart from the center of the taking lens 20 by a distance S.

The light emitting device 30 for indicating the actuation of the self-timer, as shown in FIG. 3(a), generally comprises a LED 31 that acts as a light source, a mask 32 for defining a sectional configuration of light emitted from the LED 31 to a rectangular shape similar to an aperture of the camera, a light projection lens 33 for projecting the light toward the object to be photographed.

However, the present invention is not limited to the above-mentioned embodiment of the light emitting device 30 for indicating actuation. For example, instead of providing the mask 32, a framework may be provided to the electrode of the light emitting surface of the LED 31. As long as the device is provided with a means for defining the area of light projection, many modifications can be made as in the prior art.

In the still camera 10, the light projection area of the light emitting device 30 is generally coincident with the taking area of the taking lens 20. However, since the taking lens 20 and the light emitting device 30 are located within a space S (wherein, generally S equals approximately 35 through 55 mm) therebetween, parallax is taken place between them. This makes it impossible to coincide the light projection area with the taking area along the entire distance range thereof.

In the preferred embodiment of a still camera of the present invention, there are several potential parallax problems to be considered. The schematic view of FIG. 2 shows one optical arrangement, viewed from above, wherein X.sub.1, X.sub.2 denote a borderline (this is actually a line but just for the convenience of explanation, it is referred to as a plane hereinafter)showing an angle of view spread of the taking lens 20, and Y.sub.1 and Y.sub.2 denote a borderline showing an angle of projection spread of the light emitting device 30.

FIG. 3(b) illustrates a first embodiment of the present invention. In the first embodiment, in order to make optical axis l.sub.1 of the taking lens 20 parallel with optical axis l.sub.2 of the projection lens 33 and in order to make the parallax zero at one predetermined taking distance L.sub.1, the respective points of intersection P, Q, of X.sub.1 and Y.sub.1, and X.sub.2 and Y.sub.2 are located on the line intersecting the optical axis l.sub.1 of the taking lens 20 at distance L.sub.1 at right angles.

In this way, in order to make the points of intersection of the respective borderlines as P, Q, the angle .theta..sub.1 formed between the borderline Y.sub.1 for defining the end of the light emitting device 30 within the light projection area and the optical axis l.sub.2 of the light emitting device 30, and the angle .theta..sub.2 formed between the borderline Y.sub.2 for defining the end of the light emitting device 30 projection area adjacent to the taking lens 20, and the optical axis l.sub.1 of the taking lens 20 must be the following values. Since the axes l.sub.1 and l.sub.2 are in parallel relation with each other in this embodiment, the angles are shown in the figure with reference to the optical axis l.sub.2 of the projection lens: ##EQU1## w=transverse length of the film surface; f=focal length of the taking lens;

s=space; and

L.sub.1 =predetermined taking distance.

If a person as the object is always on the line segment PQ in the above-mentioned arrangement, there is no problem. However, if the taking distance is changed, there is an untaken area A in which the taking lens 20 covers an angle less than the spread angle of the light emitting device 30 by the object taking person. Alternatively, there is a taking area B in which the taking lens 20 covers a spread angle greater than the spread angle of the light emitting device 30 and in which the indication light can not be seen by the object taking person.

In the case where the object is located within the taken area B in which the indication light is not seen, there is little problem, since the picture taking object will be included in the photograph. However, in the event the object is located within the untaken area A in which the indication light is seen, a person will be misled into believing that he will be included in the photograph. Thus, he does not move to another position, and the result is that he is not included in the picture. However, such an area as just mentioned can be reduced in actual practice so that it does not become a serious problem.

FIG. 4 is an illustration similar to FIG. 3(b), but showing a second embodiment of the present invention.

As previously described, in many cases the self-timer is used when a person, particularly the photographer, is to be included in the photograph, and the taking distance is naturally limited. Therefore, if the area, where the object is not taken, even if the indication light is seen, is eliminated by limiting the coverage to a predetermined distance, the above-mentioned problem can be substantially solved.

To this end, therefore, a near distance limit L.sub.0 and a far distance limit L.sub.2 are established as a distance range necessary for taking a picture. Light emitting device 30 is designed such that a line segment Z.sub.1 intersecting optical l.sub.1 axis right angles is intersected with X.sub.1, Y.sub.1 at one point in the near distance limit L.sub.), and that the line segment Z.sub.2 intersecting with optical axis L.sub.1 at right angles is intersected with X.sub.2 and Y.sub.2 at one point in the far distance limit L.sub.2. Specifically, the angle .theta..sub.1 formed between the borderline Y.sub.1 for defining the end of the light emitting device 30 within the light projection area and the optical axis l.sub.1 of the taking lens 20, and the angle .theta..sub.2 formed between the borderline Y.sub.2 for defining the end of the light emitting device projection area adjacent the taking lens 20, and the optical axis l.sub.1 of the taking lens 20 must be the following values. Since both axes l.sub.1 and l.sub.2 are in parallel relation with each other in this embodiment, the angles are shown in the figure with reference to the optical axis l.sub.2 of the projection lens: ##EQU2## w =transverse length of the film surface; f =focal length of the taking lens;

s =space;

L.sub.0 =near distance limit; and

L.sub.2 =far distance limit.

With the above-mentioned arrangement, although the area B, which is taken even if the indication light is not seen, is produced within the range between the near distance limit L0 and the far distance limit L.sub.2, the area A (see FIG. 3), which is not taken even if the indication light is seen, is not produced. This means that a person acting as the object to be photographed can confirm that he is located within the taking area when he sees the indication light.

FIG. 1 shows one example obtained by substituting concrete figures for FIG. 4.

In this example, the taking distance range is 1 m to b 10 m, which is usually sufficient as a picture taking distance when a self-timer is used.

If the transverse length of the film surface is established as 36 mm, and the focal length of the taking lens 20 as 35 mm, a half angle view is equal to 27.2.degree.. Likewise, a distance corresponding to the half angle view is equal to approximately 510 mm at the 1,000 mm spot, and approximately 5100 mm at the 10,000 mm spot.

If the light emitting device 30 is established by correlating it to the taking areas with the space between the optical axis l.sub.1 of the taking lens 20 and the optical axis l.sub.2 of the light projection lens 33 being set at 50 mm, angle .theta..sub.1, formed between the optical axis l.sub.2 and Y.sub.1 is equal to 24.9.degree., and the angle .theta..sub.2, formed between l.sub.2 and Y.sub.2 is equal to 27.4.degree..

In this configuration, the area which is taken even if the indication light is not seen, is very small, being 50 mm on the line segment Z.sub.1 and 500 mm on the line segment Z.sub.2 This corresponds to only 5% of the taking area, which is practically negligible.

In this embodiment, the optical axis l.sub.1 of the taking lens 20 and the optical axis l.sub.2 of the light emitting device 30 are in parallel relation with each other. However, they may be intersected at the picture taking object side. In such a case, angles .theta..sub.1 and .theta..sub.2 may be established with reference to the optical axis l.sub.1 instead of the optical axis l.sub.2 of the light projection lens.

Although the light emitting device 30 for indicating the actuation of the self-timer is usually located on the body of a camera adjacent to the taking lens 20, as previously described, it is preferably located as near as possible to the taking lens 20 in order to minimize the parallax effect, as long as it is not blocked by the lens barrel. The light emitting device 30 may even be located at the foremost end of a lens barrel of the taking lens 20.

Further, in the above-mentioned embodiment, the description has been made on the premise that the view angle of the taking lens 20 does not change. However, where a zoom lens is used as the taking lens 20, the light emitting device 30 may be designed such that the LED 31 and the light projection lens 33 are movable so that the light projection angle of the light emitting device 30 is changed in association with the zooming of the zoom lens. With such an arrangement, the light projection area can be changed to follow the change of the taking area of the zoom lens so that a person acting as the object to be photographed can know whether he will be included in any photograph that is taken.

As described in the foregoing, according to a still camera of the present invention, the light projection area of the light emitting device 30 is generally coincident with the taking area of the taking lens 20. Therefore, a person acting as the object to be photographed can know whether he will be included in the photograph, depending on whether he can see the indication light coming from the light emitting device 30.

Therefore, the situation in which a person positioned near the edge of a taken picture coverage area is not photographed when a self-timer is used can be prevented.