JPS6280634A - Photometric device for camera - Google Patents

Abstract

PURPOSE:To facilitate arranging a photoelectric converting means by inserting the photoelectric converting means to the optical path of the light which is made incident on the photoelectric converting part of a focus detector through a photographic lens and performing photometry for exposure control in accordance with the luminous flux going to the focus detector. CONSTITUTION:A vacancy 30 surrounded with a mirror box bottom part 29 is formed under a space 25 in a mirror box. A photometric device 31 for exposure control, a visual field mask 32, a field lens 33, a mirror 34, an image separating prism 35, a stop 37, a refocusing lens 38, a mirror 39, and a CCD sensor 40 as the photoelectric converting part of the focus detector are arranged there. The refocusing lens 38 is so arranged that it focuses the light passing the visual field mask 32 onto the CCD sensor 40.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a photometry device for controlling exposure used in a camera.

(Background of the Invention) Conventionally, photometry devices for eye-reflex cameras have been ones that guide a light beam to a photoelectric conversion unit using a light splitting member such as a micro beam splitter formed in a condenser lens of a finder optical system, or a light beam of a pentaprism. A method has already been proposed in which a light beam is guided to a photoelectric conversion section through a secondary imaging lens provided on an exit surface.

However, all of the above methods have problems such as interference with the light intensity distribution in the viewfinder field of view, changes in the photometric sensitivity distribution due to the split image prism on the focusing plate, and a large amount of man-hours required to adjust the sensitivity distribution. It had such drawbacks.

5, 6, and 7 are cross-sectional views of a single-lens reflex camera showing examples of the prior art, and the same parts are designated by the same reference numerals.

In FIG. 5, the subject light (the optical axis is indicated by the dashed line 2) that has passed through the photographic lens 1 is reflected upward by the mirror 3, and is then reflected upward by the focusing plate 4, the light splitting member 5, the condenser lens 6, and the pentaprism 7. The light flux passes through the eyepiece lens 8 and is separated by the light splitting member 5, and enters the photoelectric conversion unit 9. 10 is a film surface. In this method,
When viewing the subject through the eyepiece 8, a portion of the light reaching the eyepiece 8 appears to be missing due to the division of light by the light splitting member 5, and a shadow with a sharp outline appears in the center of the viewfinder. There are negative effects.

In FIG. 6, the subject light transmitted through the photographic lens 1 is reflected by the mirror 3, passes through the focusing plate 4, is redirected by the pentaprism 7, and reaches the eyepiece lens 8. Furthermore, the secondary imaging lens 11 provided on the light exit surface of the pentaprism 7 causes the central portion of the focusing plate 4 to form an image on the photoelectric conversion unit 9 . In this method, the fifth
Unlike the illustrated example, a shadow does not appear in the center of the finder, but a large number of man-hours are required for the adjustment means for focusing the center of the focus plate 4 on the center of the photoelectric conversion unit 9. Furthermore, since the light flux after passing through the focusing plate 4 is photometered, there are drawbacks such as the photometric sensitivity distribution being affected by the split image prism 4' of the focusing plate 4, and
There is a problem that the focusing plate 4 cannot be freely replaced.

Further, FIG. 7 shows an example in which the photoelectric conversion section 12 of the photometry device and the photoelectric conversion section 13 of the focus detection device are respectively arranged at the bottom of the mirror box, and a half-section is arranged at the center of the main mirror 14. A transmission section 15 is formed, and a light splitting mirror 16 is provided at the rear. The light splitting mirror 16 is formed with a semi-transmissive surface 17 on the subject side and a total reflection surface 18 on the film surface 10 side. After the light beam from the subject passes through the photographing lens 1, it is split into two directions by the main mirror 14, and one of the light beams is reflected toward the focusing plate 4 and is used for observing the field of view. A part of the other luminous flux that has passed through the main mirror 14 is reflected by the semi-transparent surface 17 on the subject side and enters the photoelectric conversion section 12 of the photometer, and the remaining luminous flux is totally reflected on the illumination surface 10 side. The light is reflected by the surface 18 and enters the photoelectric conversion unit 13 of the focus detection device.

If the photoelectric conversion section 12 of the photometric device is arranged as described above,
In the finder, only the photometric range does not become unnaturally dark, or the photometric sensitivity distribution is not affected by the split image prism 4' of the focusing plate 4.

However, it is difficult to secure storage space at the bottom of the mirror box for the photoelectric conversion unit 12 of the photometry device and the photoelectric conversion unit 13 of the focus detection device. There is a problem that the light splitting mirror 16 becomes large in size in order to form the reflecting surface 18.

(Objective of the Invention) The object of the present invention is to solve the above-mentioned problems, to facilitate the arrangement of photoelectric conversion means, to reduce costs, to improve viewfinder visibility, and to improve photometric sensitivity distribution. It is an object of the present invention to provide a photometry device for a camera that can be stabilized.

(Features of the Invention) In order to achieve the above object, the present invention photoelectrically converts a part of the light in the optical path of the light that enters the photoelectric conversion section of the focus detection device through the photographic lens, and A feature of the present invention is that a photoelectric conversion means that allows light to pass through is inserted, thereby performing photometry for exposure control from the light beam directed toward the focus detection device.

(Embodiment of the Invention) FIG. 1 is a sectional view of a single-lens reflex camera showing an embodiment of the invention.

A focusing plate 20, a pentaprism 21, and an eyepiece lens 22 are arranged above the body 19 to constitute a finder optical system.

Inside the body 19, a main mirror 23 and a submirror 2 are provided.
A mirror box interior space 25 is formed in which the main mirror 23 is retractably installed, and a semi-transparent part 26 is provided at the center of the main mirror 23. 27 is a shutter, and 28 is a film surface.

A space 30 surrounded by a mirror box bottom 29 is formed below the mirror box inner space 25, and includes a photometer 31 for exposure control, a field mask 32, a field lens 33, a mirror 34, an image separation prism 35, and an aperture 37. , a re-imaging lens 38, a mirror 39, and a CCD sensor 40 which is a photoelectric conversion section of a focus detection device.

The photometry device 31 includes an interference filter and a glass substrate (described later) in addition to a photoelectric conversion section (described later), and is installed so that the photoelectric conversion section is located near the photographing lens (shown in the figure). be done.

The re-imaging lens 38 is arranged to image the light passing through the field mass 2320 onto the CCD sensor 40. The CCD sensor 40 used has, for example, a 4 ohm element and two lines. 41 is an automatic aperture base plate, and 42 is an automatic aperture lever. 43, 44 and 45 indicated by dashed lines are optical axes.

The photometric device 31 will be described later with reference to FIGS. 2 and 3.

In FIG. 1, light (optical axis 43) transmitted through a photographic lens (not shown) is reflected by the main mirror 23 to the finder optical system (optical axis 44) and transmitted light (optical axis 44) to the photometry and focus detection system. The optical axis 45) is divided into two parts. The transmitted light is further reflected by the sub-mirror 24 and guided to the photometry device 31.

A portion of the light guided to the photometry device 31 is converted into electric power for exposure control by a photoelectric conversion section, which will be described later.

Further, the light that has passed through the field mask 32 is incident on an image separation prism 35 by a field lens 33 and a mirror 34, and is separated into two images by the image separation prism 35.

The image separation prism 35 has different inclined parts 35a,
35b is formed and projected onto the exit pupil of the photographic lens (not shown) by the field lens 33, the two images separated by the image separation prism 35 are
The light beams that have passed through different areas on the exit pupil of the photographic lens are converted to COD via the re-imaging lens 38 and the mirror 39.
The light is input to Senna 4o. Therefore, the optical system from the field lens 33 to the CCD sensor 40 acts as a focus detection system using a known phase difference detection method, and by detecting the phase difference in the light intensity distribution of the ostium of the field mask 32,
The amount of defocus of the photographic lens is calculated.

FIG. 2 is a front view of the photometric device 31, and FIG. 3 is a perspective view showing details of the photometric device 31.

The photometric device 31 is configured such that an interference filter 47 and a photoelectric conversion section 48 are disposed on the front and back sides of a glass substrate 46 . 49 indicated by a broken line is an opening of the field mask 32 (FIG. 1).

The photoelectric conversion section 48 includes linearly arranged amorphous silicon light receiving elements 50, 51, 52, and light transmitting sections 53, 54.
, 55 and hyamorphous silicon photodetector 50.51.
The connecting portions 56,57 are connected to each other by connecting terminals 58,59.
Connected to a logarithmic compression circuit (described later).

The amorphous silicon light receiving elements 50, 51, 52 are made of amorphous silicon layers 60, 61, 6 formed in a linear shape.
2, and upper electrodes 63, 64, 65 arranged in a stacked manner above and below.
and a lower electrode 66°67.68.

FIG. 4 shows an example of a circuit diagram connected to the photoelectric conversion section 48 shown in FIGS. 2 and 3. FIG.

A connection terminal 58 of the photoelectric conversion unit 48 is connected to a power supply VC having a reference voltage and a non-inverting input terminal of an operational amplifier 69,
Connection terminal 59 is connected to the inverting input terminal. A feedback circuit having a logarithmic compression diode 70 is connected between the output terminal and the inverting input terminal of the operational amplifier 69, and the logarithmic compression diode 70 and the operational amplifier 69 form a logarithmic compression circuit.

The output terminal of operational amplifier 69 is connected to the inverting input terminal of operational amplifier 720 via variable resistor 71 .

The inverting input terminal is connected to a feedback circuit having a resistor 73 and to ground via a variable resistor 74. A power supply (2) is connected to the non-inverting input terminal of the operational amplifier 72.

Operational amplifier 72 and resistors 71, 73, and 74 constitute an inverting amplifier circuit.

The output terminal of the operational amplifier 72 receives film sensitivity information l5O.
It is connected so as to be inputtable to an arithmetic control circuit 75 into which the maximum aperture information Ayo and the maximum aperture correction information Ay+2 of each photographing lens are respectively input.

The arithmetic control circuit 75 is connected to control an aperture control device 76 and a shutter speed control device 77.

The operation will be explained below with reference to FIGS. 1, 2, 3, and 4.

When a part of the light passing through the side light device 31 is received by the amorphous silicon light receiving element 50, 51, 52, it is photoelectrically converted and a current is generated. This generated current is logarithmically compressed by a logarithmic compression circuit to a current proportional to the logarithm of the amount of received light, inverted and amplified by an inverting amplifier circuit, and input to the arithmetic control circuit 75 .

In the calculation control circuit 75, the aperture value and shutter speed of the photographic lens are calculated and determined based on the information from the inverting amplifier circuit, the film sensitivity information ISO, the maximum aperture information Avo, and the maximum aperture correction information Ayc, and the aperture control is performed. device 76
and a shutter speed control device 77 are controlled.

In the embodiments shown in FIGS. 1, 2, and 3, the optical system of the focus detection device is housed in the space 3o formed by the mirror box bottom 29 of the podium 19, and the submirror 2
In the optical path guided from 4 to the optical system of the focus detection device,
Since the photometric device 31 that is integrated with the glass substrate 46, the sensitivity correction interference filter 47, and the photoelectric conversion section 48 is provided, there is no need to newly provide an interference filter for the photometric device 31.

Further, there is no need for a photometric imaging optical system such as a secondary imaging lens or a light splitting member for the photometric device 31, and furthermore, the submirror 24 can be used for both photometry and focus detection, making it possible to reduce costs. .

In addition, the omission of the secondary imaging lens or light splitting member eliminates the need for alignment between the photometric imaging optical system and the photometric light receiving element, so the photometric sensitivity distribution, which conventionally requires a large number of man-hours, can be improved. The adjustment means can be almost eliminated.

Since the light beam from the photographing lens is divided by the main mirror 23, there is no possibility of partial drop in light intensity in the viewfinder field of view (also, since the split image prism has no effect on the photometric sensitivity distribution, Focus board 2
0 can be freely exchanged for (.

Furthermore, linear amorphous silicon light receiving elements 50, 51, 52 are arranged in a blind pattern on the light output side of the glass substrate 46, and an interference filter 47 for photometry and focus detection is provided on the light input side, so that the spectral sensitivity can be improved. Since the correction is made, a single glass substrate 46 can be used, and the light receiving area of the photometric device 31 can be increased to improve efficiency.

(Correspondence between the invention and the embodiments) The photoelectric conversion section 48 corresponds to the photoelectric conversion means of the present invention, and the CC
The D sensor 40 corresponds to the photoelectric 4 converter of the focus detection device.

(Modification) In the illustrated embodiment, a linear amorphous silicon light receiving element 50, 51, 52 is used, but a light receiving element made of other materials may be used. The elements may be scattered. Further, structures other than the photometric device 31 are not limited to the illustrated embodiment.

(Effects of the Invention) As described above, according to the present invention, in the optical path of the light that enters the photoelectric conversion section of the focus detection device through the photographic lens, a part of the light in the optical path is photoelectrically converted, and the remaining part is converted into an optical path. By inserting a photoelectric conversion means that allows light to pass through, photometry for exposure control is performed from the light beam directed toward the focus detection device.
The photoelectric conversion means can be easily arranged, the cost can be reduced, and the visibility of the finder can be improved.
The photometric sensitivity distribution can be stabilized.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a single-lens reflex camera equipped with an embodiment of the present invention, Fig. 2 is a front view showing an embodiment of the invention, and Fig. 3 is a perspective view showing details of an embodiment of the invention. 4 is a circuit diagram of a circuit connected to the photoelectric conversion unit according to the present invention, FIG. 5 is a sectional view showing an example of a conventional type, and FIG. 6 is a sectional view showing another example of the conventional type. FIG. 7 is a sectional view showing another example of the conventional type. 19...Body, 23...Main mirror, 24...Length mirror, 25...Space inside mirror box, 26...
・Semi-transparent part, 29...Mirror box bottom, 30...
・Vacancy, 31...Photometric device, 32...Field mask,
33...Field lens, 34...Mirror, 35
---Image separation prism, 38...Re-imaging lens, 39
...-Mirror, 40...CCD sensor, 43°44.
45... Optical axis, 46-... Glass substrate, 47... Interference filter, 48... Photoelectric conversion unit, 49... Opening, 50, 51.52-... Amorphous silicon light receiving element, 53 , 54.55...transparent part, 58.59...
Connection terminal, 60, 61. 62... Amorphous silicon layer, 63, 64. 65... Upper electrode, 66.67.
68...lower electrode. Patent applicant: Minoru Nakamura, Canon Co., Ltd. Figure 1 Figure 4 150 AVOAV 11° Figure 5 Figure 6

Claims (1)

[Claims] 1. In a camera photometry device having a photoelectric conversion means arranged near the expected image forming plane of the photographic lens, part of the light in the optical path that enters the photoelectric conversion section of the focus detection device through the photographic lens is 1. A photometry device for a camera, characterized in that said photoelectric conversion means is inserted for photoelectrically converting a portion of the light and passing the remaining light.