JPS59129838A - Automatic focus photographing device - Google Patents

Abstract

PURPOSE:To raise the reliability of an automatic focusing accuracy by providing an auxiliary projecting means for projecting a light in the direction of an object to be photographed being within the closest fucusing distance of a photographic lens in addition to a main projecting means. CONSTITUTION:A projecting lens 2, projecing light emitting element 3, photodetecting lens 4 and a photodetecting photosensitive element 5, which are installed in a camera body 1 execute a range finding operation extending from the closest focusing distance l in which photographing can be executed, to the infinity distance, and are the same as the constitution of a conventional automatic focus detecting mechanism. Also, an auxiliary projecting means consisting of a fixed auxiliary projecting light emitting element 6 for projecting an irradiated luminous flux toward an object to be photographed being within the closest focusing distance l only, and an auxiliary projecting lens placed on the front of said element are provided in the camera body 1, and luminous flux for irradiating an object to be photographed, from the projecting light emitting element 3 projects a light continuously extending from the vicinity of the closest focusing distance of a photographic lens to the vicinity of the infinity by turning the projecting light emitting element 3 for generating, for instance infrared-rays.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an autofocus photographing device that is incorporated into, for example, an intermediate camera, and is particularly equipped with a close-up object discrimination mechanism for determining the presence or absence of an object within the closest distance of a photographic lens. .

Conventional irradiation-type automatic focus photography devices used in intermediate-level cameras, etc., do not activate the distance measurement function when the subject is closer than the range that can be measured, or when the subject is in an area that cannot be illuminated. As a result, the photographic lens is focused on a preset infinite distance, which has the serious drawback that the photograph becomes out of focus.

In other words, reflected light cannot be obtained from a subject existing within the closest distance ρ, and reflected light from a luminous flux emitted in an infinite direction is a fixed distance, for example, approximately 5 m to 15 m.
If it is more than m, it will not be returned at all. In this way, if the light-receiving photosensitive element does not detect reflected light, it means that the subject is either within the closest distance or near infinity. Since it is impossible for a photographic device to determine this, the photographing lens is generally set at a preset infinite distance.

An object of the present invention is to provide a simple close-up object detection mechanism that determines the presence or absence of an object within the closest distance of the photographing lens, in order to eliminate the drawbacks of the conventional device. The purpose of the present invention is to provide an autofocus photographing device that issues a warning etc. to prevent out-of-focus photographs. , and a light receiving means for detecting the reflected light from the subject of the luminous flux emitted from the light projecting means, and an auxiliary light projecting light in the direction of the subject within the closest distance of the photographing lens in addition to the main light projecting means. It is characterized by providing means.

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a camera equipped with an automatic focus detection plate comprising a light projecting means having a movable light projecting element and a fixed light receiving means. A light emitting lens 2, a light emitting element 3, and a light receiving lens 4 installed inside the camera body l.
The light-receiving photosensitive element 5 is a component of a conventional automatic focus detection mechanism that performs distance measurement operations from the closest distance ρ that can be photographed to an infinite distance. Furthermore, inside the camera body 1, there is a fixed auxiliary light emitting element 6 that emits the irradiation light beam towards the subject within the closest distance β, and an auxiliary light emitting lens 7 arranged in front of the fixed auxiliary light emitting element 6. An auxiliary light projecting means consisting of is installed inside.

The luminous flux emitted from the light emitting element 3 for projecting light for illumination of the subject can be continuously transmitted from near the closest distance of the photographing lens to near infinity by rotating the light emitting element 3 for projecting light emitting infrared light, for example. is illuminated. In the drawing, A indicates the luminous flux near the closest pressure # and β, B indicates the luminous flux towards the intermediate distance, and C indicates the luminous flux towards infinity, but these luminous fluxes A, B, and C When a subject exists at a position where the beam is irradiated, the light-receiving photosensitive element 5 senses the reflected light from the subject, and calculates the subject distance from the rotation angle of the light beam, for example.

However, at such a long distance that the reflected light does not return, there is no output from the light-receiving sensitive element 5, and in this case, the photographing lens is adjusted to infinity as described above.

Further, the auxiliary light emitting element 6 and the auxiliary light emitting lens 7
The luminous flux from the auxiliary light projecting means consisting of the closest distance ρ
If there is a subject here, the reflected light enters the light-receiving photosensitive element 5, so the closest pressure fa
The presence or absence of a subject within ρ is determined. In this case, by shortening the focal length of the auxiliary light projection lens 7, it is possible to irradiate the emitted light beam over a wider range of distance within the closest distance. The reason for this is that within normal shooting distances, the diameter of the emitted light beam is limited in order to improve distance accuracy, but if you only want to determine whether the subject is within the closest distance, the distance measurement accuracy will be limited. This is because there is no need to take this into consideration, and the beam may be irradiated over a wide range.

In reality, the luminous flux A- from the main light emitting element 3
In order to distinguish between C and the luminous flux from the auxiliary flashing lens 6, the auxiliary flashing means confirms whether or not there is a subject within the closest distance 1i111N in the first step of distance measurement, and then It is necessary to carry out a two-step distance measurement operation in which distance measurement is performed using the conventional main light emitting optical system.

Next, FIG. 2 shows another embodiment of the present invention,
Components that are the same as in FIG. 1 are designated by the same reference numerals. The difference from the previous embodiment is that two light-receiving photosensitive elements 5a and 5b are used as light-receiving elements, and the light-emitting element 3 for projecting light is used until the output of both becomes equal, that is, until the object is detected. is rotated by a servo mechanism. Even in the method of this second embodiment, the reflected light does not return near infinity or within the closest distance RnR, so similarly to the first embodiment shown in FIG. It becomes out of focus. Therefore, the auxiliary light emitting element 6 and the auxiliary light emitting lens 7
By adding an auxiliary light projecting means consisting of the following, it becomes possible to confirm the presence or absence of a subject within the closest distance using the same principle as in the case of FIG.

In the embodiment, the light-receiving device for the main light projecting device is used to receive light for the auxiliary light projecting device, but a dedicated light receiving device for the auxiliary light projecting device may be provided. In this case, if the two luminous fluxes can be distinguished, simultaneous operations will be possible, and there will be no need to carry out the distance measuring operation in two stages as described above, which has the advantage of shortening the distance measuring time.

As mentioned above, the auxiliary flashing means can detect whether or not a subject exists within the closest distance, and if its presence is detected, it will turn on a warning lamp in the viewfinder or issue a warning. It is possible to give a warning to the photographer in various ways, such as by sounding a buzzer or by disabling the shirt release.

As explained above, the automatic focus photographing device according to the present invention has the following features:
By adding an extremely simple auxiliary light projecting means, it is possible to prevent out-of-focus photographs that occur when the subject is within the closest distance, and it is possible to improve the reliability of automatic focusing accuracy.

[Brief explanation of the drawing]

The drawings show an embodiment of an automatic focus photographing device according to the present invention,
FIG. 1 is a block diagram of the first embodiment, and FIG. 2 is a block diagram of the second embodiment. Reference numeral 1 denotes the photographing device main body, 2 a lens for projecting light, 3 a light emitting element for projecting light, 4 a lens for receiving light, 5.5a and 5b light sensitive elements for receiving light, 6 a light emitting element for auxiliary light projecting, 7 is the auxiliary light projection lens, A, B, and C are the luminous fluxes emitted by the light projection light emitting elements,
D is the luminous flux emitted by the auxiliary light emitting element, and ρ is the closest distance to the photographing lens. Patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] 1. It has a main light projecting means for projecting light onto a subject existing within the photographable range of the photographing lens, and a light receiving means for detecting the reflected light from the subject of the luminous flux emitted from the light projecting means. An automatic focus photographing apparatus characterized in that, in addition to the upper light projecting means, an auxiliary light projecting means is provided for projecting light in the direction of a subject within the closest distance of the photographing lens. 2. The automatic focus photographing device according to claim 1, wherein the light receiving means for the auxiliary light projecting means also serves as a light receiving means for the light reflected by the main light projecting means.