JPH08220585A - Electronic camera - Google Patents

Abstract

PURPOSE: To increase the quantity of light incident on a light measuring means extensively without reducing the quantity of light incident on an image pick-up element, by leading the first light flux and the second light flux reflected by an image pick-up means and a reflecting means to the light measuring means. CONSTITUTION: The light flux A of a subject image is divided into a light flux B toward an image pick-up element 19 and a light flux C toward a total reflecting mirror 21 by a beam splitter 15, and thereafter, a light flux D and a light flux F reflected by the element 19 and the total reflecting mirror 21 are led to a light measuring element 25. As a result, the quantity of light incident to the element 19 is not reduced, and the quantity of light incident to the light measuring element 25 can be increased extensively. In other words, since both the reflecting light of the beam splitter 15 and the reflecting light of the element 19 are injected to the light measuring element 25, a light flux of the incident light quantity larger than the conventional system is to be injected to the light measuring means 25, and as a result, the output of the light measuring element 25 is increased, and the influence by a disturbance such as a noise is hardly received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera such as an electronic still camera.

[0002]

2. Description of the Related Art Generally, in an electronic camera such as an electronic still camera, an image pickup device for converting a subject image projected by a photographing lens into an electric video signal is arranged, and the brightness of the subject image is measured. A photometric sensor is installed. And conventionally, as such an electronic camera,
For example, the one disclosed in JP-A-63-62478 is known.

[0003]

However, in the conventional electronic camera, generally, when the light amount decreases, the output of the photometric sensor, which is a photoelectric conversion element, becomes small, the proportion of noise in the output signal increases, and the photometric error increases. There's a problem.

On the other hand, even in the case of an image pickup device which is the same photoelectric conversion device, a decrease in the amount of incident light is not preferable because it causes deterioration of image quality due to generation of noise. Therefore, it is desirable that as much light as possible be incident on both the image sensor and the photometric sensor. For example, in the electronic camera disclosed in JP-A-63-62478, if the transmittance of the beam splitter is 95% and the reflectance is 5%, the amount of light incident on the photometric sensor is transmitted through the taking lens. Of this amount, 5% and 95% of the light amount is incident on the image sensor.

Here, if the transmittance of the beam splitter is increased, the amount of light incident on the image sensor is increased, but the amount of light incident on the photometric sensor is decreased. On the other hand, if the reflectance of the beam splitter is increased, the amount of light incident on the photometric sensor increases, but the amount of light incident on the image sensor decreases. In contrast to such contradictory conventional techniques, there has been a demand for a technique of increasing the amount of light incident on the photometric sensor without reducing the amount of light incident on the image sensor.

The present invention has been made in response to such a conventional situation, and an electronic camera capable of significantly increasing the amount of light incident on the photometric means without reducing the amount of light incident on the image pickup device. The purpose is to provide.

[0007]

According to another aspect of the present invention, there is provided an electronic camera comprising: a projection means for projecting a subject image; an imaging means for converting the subject image projected by the projection means into an electric video signal; and the subject. In an electronic camera provided with a photometric means for measuring the brightness of an image, between the projection means and the imaging means, the light flux of the subject image is directed to a first light flux toward the imaging means and toward the reflection means. And a light beam splitting unit for splitting the first light beam and the second light beam reflected by the image pickup unit and the reflecting unit to the photometric unit. To do.

According to a second aspect of the present invention, in the first aspect, the light beam splitting means is a beam splitter. According to a third aspect of the present invention, in the second aspect, the beam splitter is integrally formed with the reflecting means.

[0009]

According to the electronic camera of the present invention, the luminous flux splitting means splits the luminous flux of the object image into a first luminous flux toward the image pickup means and a second luminous flux toward the reflecting means, and thereafter, the image pickup means. The first light flux and the second light flux reflected by the reflection means are guided to the photometric means.

According to another aspect of the electronic camera, the light beam splitting means is formed by a beam splitter. In the electronic camera of claim 3, the beam splitter is integrally formed with the reflecting means.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of an electronic camera of the present invention. In this electronic camera, the light flux from a subject image (not shown) is taken by the taking lens 11, diaphragm 13, beam splitter 15, optical low-pass filter 17
And enters the image sensor 19. Beam splitter 1
5, a total reflection mirror 21 is provided above the beam splitter 15, and a condenser lens 23 and a photometric element 2 are provided below the beam splitter 15.
5 are provided.

The taking lens 11 comprises lenses 27 and 29 and is held by a lens barrel 31. The lens barrel 31 has a housing 33.
It is fixed by screws 35. A first coupling member 37 having a plurality of protrusions 37a is arranged on the right side of the housing 33. The first coupling member 37 includes the fixed plate 39 and the housing 3.
It is arranged between 3 and 3.

A screw hole 39a is formed in the fixed plate 39, and a through hole 37b is formed in the first coupling member 37. Then, screw 41 from the housing 33 side,
The first coupling member 37 is sandwiched and fixed between the fixing plate 39 and the housing 33 by being screwed into the screw holes 39 a formed in the fixing plate 39.

The through hole 37b of the first coupling member 37 through which the screw 41 penetrates has a size sufficiently larger than the diameter of the screw 41, and is orthogonal to the optical axis O when the screw 41 is loose. It is possible to move a little in the direction. The image sensor holding member 43 is fixed to the second coupling member 45 with a screw (not shown), and the optical low-pass filter 17, the dust-proof rubber 47, and the image pickup device are provided between the image sensor holding member 43 and the second coupling member 45. The element 19 is sandwiched.

The second coupling member 45 is integrally provided with a plurality of cylindrical protrusions 45a, and the protrusions 37a of the first coupling member 37 are fitted to the tips thereof. Also,
A bellows-shaped dustproof rubber 49 is provided between the housing 33 and the image sensor holding member 43. The operation of the electronic camera of the first embodiment will be described below.

In this electronic camera, a light flux A emitted from a subject (not shown) is incident on the taking lens 11, is focused by the diaphragm 13 to a predetermined amount, and then is incident on the beam splitter 15. The beam splitter 15 is 5 for the light flux A.
% Of the luminous flux C is reflected and 95% of the luminous flux B is transmitted.

The light beam B passes through the optical low pass filter 17 and enters the image pickup element 19. The light flux B is reflected by the image pickup element 19 and becomes a light flux D and is incident on the beam splitter 15 again. The luminous flux D is about 40 compared to the luminous flux B.
The amount of light is 38% compared to the percentage, and the luminous flux A.

A part of the light beam D is reflected downward by the beam splitter 15, and 5% of the light beam D and 2% of the light beam A become a light beam E and enter the condenser lens 23. Then, the light enters the photometric element 25. On the other hand, the light flux C is reflected by the total reflection mirror 21 and becomes the light flux F with almost no loss of light quantity.
Incident again.

95% of the luminous flux F and 4.8% of the luminous flux A are condensed as the luminous flux G by the condenser lens 23 and enter the photometric element 25. As a result, the light flux E and the light flux G are combined to be 6.
Eight percent of the luminous flux enters the photometric element 25. This value is the same as the conventional example in which, when a beam splitter having a reflectance of 5% is used, the amount of light incident on the image sensor is the same, but only 5% of the light flux A is incident on the photometric element. Compared to about 36
% Also means that the amount of light incident on the photometric element 25 is increasing.

As described above, the light amount control of the flash light emitting device such as a strobe is performed on the basis of the luminous flux incident on the photometric element 25. Further, the light flux incident on the image pickup element 19 is recorded on a recording medium through a signal processing circuit (not shown).
In the electronic camera configured as described above, the beam splitter 15 splits the light flux A of the subject image into a light flux toward the image sensor 19 and a light flux C toward the total reflection mirror 21, and thereafter, the image sensor 19. And total reflection mirror 21
Since the light flux D and the light flux F reflected by are guided to the photometric element 25, the quantity of light incident on the photometric element 25 can be significantly increased as compared with the conventional case without reducing the quantity of light incident on the imaging element 19.

That is, in the above-described embodiment, both the reflected light of the beam splitter 15 and the reflected light of the image pickup device 19 are incident on the photometric device 25. Therefore, for example, when the beam splitter 15 having a reflectance of 5% is used. The luminous flux of 6.8% of the amount of incident light which is larger than that in the conventional case is incident on the photometric element 25.
The output of 5 increases, and it is less likely to be affected by disturbance such as noise.

If it is not necessary to increase the amount of light incident on the photometric element 25, the light transmittance of the beam splitter 15 can be increased so that more light flux can enter the image pickup element 19. In the electronic camera described above, the light fluxes C and F and the light fluxes B and D reciprocate in the same optical path, so that the light from the taking lens 11 to the photometric element 25.
It is possible to secure the required optical path length up to and to downsize the device.

Further, since the light beam splitting means is formed by the beam splitter 15, the light beam splitting means can be easily and surely constructed. Furthermore, in the electronic camera described above, the second coupling member 45 is connected to the first coupling member 37 that can be separated from the housing 33, so that the position adjustment of the taking lens 11 and the image sensor 19 becomes easy. .

FIG. 2 shows a second embodiment of the electronic camera of the present invention. The parts having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the front side of the beam splitting surface 59a of the beam splitter 59 extends upward, and the total reflection mirror 61 is formed on the upper surface of the extending portion 59b by total reflection coating. 61 and 61 are formed integrally.

In this embodiment, since the beam splitter 59 and the total reflection mirror 61 are integrally formed, the number of parts can be reduced and the assembling property can be improved. FIG. 3 shows a third embodiment of the present invention, and parts having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. This third
The example is a taking lens 6 used with 35 mm film.
A device for reducing and projecting an aerial image of 36 mm × 24 mm square formed on the primary image plane 65 by 3 onto the image sensor 19 having an effective pixel size of about 9 mm × 7 mm, and recording the image as an electric signal. is there.

In this apparatus, the light flux condensed by the taking lens 63 is reflected upward by the 45-degree mirror 67 and focused on the focusing screen 69, and then the subject brightness is measured by the photometric optical system 71, and the finder optical system is used. The system 73 allows the subject image to be viewed by the user. On the other hand, at the time of shooting, the 45-degree mirror 67 is retracted upward, the shutter 75 is opened,
The aerial image formed by the taking lens 63 is the primary image plane 6
5. A field lens 7 formed on the image 5 and provided after that
7, the relay lens 79, and the beam splitter 15, the light enters the image sensor 19 and forms an image as in the first embodiment.

Although the relay lens 79 is usually composed of a plurality of lenses, it is shown as an ideal single thin lens for the sake of explanation. Also in the above-described configuration, as in the first embodiment, a part of the light flux incident on the beam splitter 15 is transmitted to the image pickup element 19, and the reflected light is reflected by the beam splitter 15 again, and the photometric element 25.
Incident on.

The rest of the light beam incident on the beam splitter 15 is reflected by the total reflection mirror 21, and the light beam reflected by the total reflection mirror 21 passes through the beam splitter 15 again and enters the photometric element 25. Therefore, as in the first embodiment, it is possible to increase the amount of light incident on the photometric element 25 without decreasing the amount of light incident on the image sensor 19.

In this embodiment, the taking lens 63
The subject image formed on the primary image forming surface 65 by the reduction optical system 81 having the field lens 77 and the relay lens 79.
Can be further reduced in size and projected on the image pickup device 19. FIG. 4 shows a fourth embodiment of the present invention, and parts having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the first coupling member 83 is provided in the housing 85 through an adjustment allowance 87 formed of a gap, and after adjusting the image pickup element 19, an adhesive is applied to the adjustment allowance 87. It is designed to be filled. In this embodiment, an adjustment allowance 91 is provided between the first connecting member 83 and the second connecting member 89.
Is provided so that the adhesive can be filled.

As the adhesive, a molten metal such as solder may be used in addition to the epoxy resin, but it is necessary to join the peripheral members while cooling them so as not to cause thermal expansion. Also in the fourth embodiment, it is possible to obtain substantially the same effect as in the second embodiment.

Then, in this embodiment, the thermal expansion coefficients of the respective members are set so that the thermal expansion amounts of the housing 85 and the first coupling member 83 are equal to the thermal expansion amounts of the second coupling member 89. As a result, it is possible to prevent image blurring due to thermal expansion. Also, in this embodiment, the second coupling member 89
Need not be fitted to the first coupling member 83, the degree of freedom in design can be increased accordingly.

[0034]

As described above, in the electronic camera of the first aspect, the luminous flux splitting means divides the luminous flux of the object image into the first luminous flux toward the image pickup means and the second luminous flux toward the reflecting means. The first light flux and the second light flux that have been split and then reflected by the imaging means and the reflection means are guided to the photometric means, and therefore enter the photometric means without reducing the amount of light incident on the imaging element. The amount of light can be increased significantly compared to the conventional one.

That is, in addition to the luminous flux directly incident on the photometric element from the luminous flux splitting means, the luminous flux reflected by the image pickup element is also incident on the photometric element, so that it is incident on the photometric means without reducing the amount of light incident on the image pickup element. It is possible to increase the amount of light to be emitted. In the electronic camera of the second aspect, since the light beam splitting means is formed by the beam splitter, the light beam splitting means can be easily and surely constructed. In the electronic camera of the third aspect, since the beam splitter is integrally formed with the reflecting means, there is an advantage that the number of parts can be reduced and the assemblability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of an electronic camera of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the electronic camera of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the electronic camera of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the electronic camera of the present invention.

[Explanation of symbols]

 11 Photographing lens 15 Beam splitter 19 Imaging device 21,61 Total reflection mirror 25 Photometric device

Claims (3)

[Claims] 1. A projection means for projecting a subject image, an image pickup means for converting the subject image projected by the projection means into an electrical video signal, and a photometric means for measuring the brightness of the subject image. In the electronic camera, the light flux of the subject image is divided into a first light flux toward the image pickup means and a second light flux toward the reflecting means, and the image pickup is performed between the projection means and the image pickup means. Means and said first light flux and second light reflected by said reflecting means
The electronic camera is characterized in that a luminous flux splitting means for guiding the luminous flux of 1. to the photometric means is arranged. 2. The electronic camera according to claim 1, wherein the light beam splitting means is a beam splitter. 3. The electronic camera according to claim 2, wherein the reflecting means is integrally formed with the beam splitter.