JPS5813895B2 - Ichigan Reflux Camera No. Sono Sotsu Kousouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called TTL photometry method for a single-lens reflex camera and its apparatus.

2. Description of the Related Art Conventionally, a photometric device is known in which a plurality of photoelectric conversion elements are disposed around an eyepiece lens constituting a finder optical system, and the amount of light of a subject is measured from electrical signals from the photoelectric conversion elements.

That is, in FIG. 1, numeral 1 is a focus plate on which the subject light flux that has passed through the photographing lens and whose direction has been changed by an oblique mirror forms an image, numeral 2 is a condenser lens, and numeral 3 is a pentaprism.

Reference numeral 3a denotes a front reflecting surface, and the light beam of the finder image light beam that is reflected by this surface 3a and directed toward the eyepiece lens 4 will be referred to as a regularly reflected light beam.

Further, P1, P2, P3 and P4 are each photoelectric conversion elements.

Here, photometry is performed by measuring the normally reflected light beam by using the buttons of elements P1 and P2, or the pair of elements P3 and P4, which are a set of elements.

The reason for this is that since the positions of the individual photoelectric conversion elements are displaced from the viewfinder optical axis, the directional output characteristics of the individual elements are directed toward a portion offset from the center of the viewfinder image screen.

Therefore, a method is used to eliminate the deviation of the directional output characteristics from the center by combining the outputs of each element, but the sensitivity characteristics of each element are regulated within a certain range, and the characteristics between each element are also maintained in a certain relationship. need to be maintained.

However, these steps are extremely complicated and time consuming in manufacturing the photometric circuit.

This invention uses optical means to guide separate partial luminous fluxes outside the finder effective luminous flux within the finder image luminous flux that undergoes regular reflection onto the same photoelectric conversion element light receiving surface.
The aim is to eliminate the aforementioned difficulties.

Therefore, in the present invention, a single photoelectric conversion element is provided obliquely, oriented toward the output surface of the photometric light flux formed in the pentaprism and outside the effective light flux of the eyepiece, and the finder optical axis of the photoelectric conversion element is sandwiched between the two photoelectric conversion elements. The basic configuration is to provide a reflective optical system on the opposite side of the solder, so that part of the light beam from the subject that is regularly reflected by the pentaprism is directly incident on the photoelectric conversion element, and the other part is The light is incident on the same photoelectric element via the reflective optical system.

Examples of the present invention will be described below.

In the figure, 1 is a focus plate, 2 is a condenser lens, 3 is a pentaprism, 3a is a front reflective surface, 3b is an exit surface, and 4 is an eyepiece lens.

In FIG. 2, 3c is a notch formed in the pentagonal prism, which is formed by a light flux guiding surface 30' and 3c''.

3d is a reflecting surface, which is an optical means for changing the direction of a part of the regularly reflected light beam.

Further, 1 or ■ is the diffuse component light that is regularly reflected from the focus plate where the finder image is formed.

P is a photoelectric conversion element.

F is a filter, and other light amount limiting means may be used.

With the above-described structure, a part (1) of the light beam regularly reflected in the pentaprism exits the pentaprism from the output surface 3c' of the notch 3c and enters the light receiving surface of the element P.

On the other hand, the other light beam (2) is reflected by the reflecting surface 3d, changes its direction, exits from the output surface 3c'', and is received by the same element P as described above.

Therefore, both light quantity information components are combined on the light receiving surface.

Note that the filter F is provided to maintain a balance in the amount of light between the two luminous fluxes (■ and H), and such a means is used, for example, when a photoelectric conversion element or a recessed portion is
This is especially necessary when the shaft is rotated 90 degrees around the center.

Figure 3 shows the photometric distribution of the luminous flux ■ and the luminous flux ■ incident on the element P on the surface of the focus plate, where the luminous flux ■ is biased upward and the luminous flux ■ is biased downward from the center of the viewfinder screen. .

By combining both of the light fluxes on the light receiving surface of the photoelectric conversion element, the center of the combined photometric distribution coincides with the center of the finder screen.

Next, another embodiment will be explained according to FIG.

In the figure, 5 is an optical block, and 5a is a lead-out part, in which a stepped prism or a diffuser is formed to prevent total reflection.

5b is a reflective surface, and the optical block 5 is preferably bonded to the exit surface 3b, but there may be a gap.

The light beam ■ advances from the pentaprism 3 to the optical block 5,
The light is emitted from the lead-out portion 5a and is incident on the light receiving surface of the element P.

Further, the light beam (2) travels from the pentaprism 3 to the optical block 5, is reflected by the reflective surface 5b, exits from the output portion 5a, and enters the light receiving surface of the element P.

Here, the optical block is made of optical glass, optical plastic, or the like.

FIG. 5 shows another embodiment, in which the light flux incident on the light-receiving surface of the photoelectric conversion element P is guided at an angle that does not cause total reflection on a surface in close contact with the light-receiving surface. This is the one taken.

In the figure, 6 is a deformed optical block, 6a is a first reflective surface, 6b is a second reflective surface, and 6c is a surface with which the element P is in close contact.

This optical block 6 is preferably bonded to the exit surface 3b.

The light flux ■ advances from the pentaprism 3 to the optical block 6,
The light is incident on the light receiving surface of element P.

On the other hand, the light flux {circle around (2)} travels from the pentaprism 3 to the optical block 6, is reflected by the first reflective surface 6a, then the second reflective surface 6b, and then enters the light receiving surface of the element P.

Therefore, the two photometric information components are combined on the light receiving surface, and the combined photometric distribution corresponds to the center of the viewfinder screen.

In the illustrated example, a photoelectric conversion element is disposed on the second reflecting surface 6b, and the inclination angle is changed with the reflection direction 6c, so that the luminous flux {circle around (2)}
The light may be reflected and guided to the element.

In short, this invention guides component light beams with different photometric distribution ranges within the normal reflected light beam to the photoelectric conversion element of Yoichi through an optical means provided between the front reflection surface of the pentaprism and the eyepiece. This eliminates the need for restrictions based on differences in characteristics of each element.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining a known photometry method, Fig. 2 is a side view of an embodiment of the present invention, Fig. 3 is a diagram showing the photometry distribution state on the focus plate, Figs. Each figure is a side view of another embodiment of the invention. In the figure, 3c...notch part, 3c', 3c"...leading-out surface 3d
... Reflective surface, 5... Optical block, 5a... Derivation part, 5b... Reflective surface, 6... Deformed optical block, 6 a , 6b... Reflective surface, P... Photoelectric conversion element.

Claims (1)

[Claims] 1. A pentaprism having a reflective surface on the lower side of the exit surface is arranged in the optical path of the finder system, and a Gakuichi light-receiving element is placed above the exit surface of the Penck prism at an angle with respect to the exit surface. The light beam regularly reflected within the pentaprism and directed downward from the exit surface of the pentaprism is reflected by the reflection surface, then crosses the optical axis of the finder system and reaches the light receiving element. A photometric device for a single-lens reflex camera, characterized in that a light beam directed upward from an exit surface of the pentaprism is directly emitted from the exit surface and then guided to the light-receiving element. 2. A pentaprism is arranged in the optical path of the finder system, and an optical block having at least one reflective surface is arranged in close contact with or with a slight spacing in the exit direction of the pentaprism, and above the optical block there is a A light beam that is regularly reflected within the pentaprism with a light receiving element arranged therein,
The light flux directed above the exit surface of the pentaprism is directly emitted from the exit surface, passes through the optical block, and then guided to the light receiving element, and the light flux directed below the exit surface of the pentaprism is directed to the light receiving element. A single-lens reflex camera characterized in that light is emitted from an exit surface, reflected in the reflection direction of the optical block, passed through the optical block so as to cross the optical axis of the finder system, and then guided to the light receiving element. photometric device. 3 Place a pentaprism in the optical path of the finder system, place an optical block with a plurality of reflective surfaces in close contact with the exit surface of the pentaprism or with a slight interval, and place the prefecture's best light-receiving surface above the optical block. A light beam that is regularly reflected within the pentaprism and a light beam that goes above the exit surface of the pentaprism and a light beam that goes below the exit surface of the pentaprism reach the exit surface. After passing through the optical block, each light beam is reflected at least once on the reflective surface of the optical block, and one of the light beams crosses the optical axis of the finder system due to reflection from the reflective surface and passes through the optical block. A photometric device for a single-lens reflex camera, characterized in that light is guided to the light receiving element.