JPS6385529A - Photometer for electronic camera - Google Patents

Abstract

PURPOSE:To guide reflected light efficiently from a solid-state image pickup element to a photoelectric converting element for light measurement by providing a light-shielding reflecting means between photodetection parts of respective picture elements of the color separation filter of the solid-state image pickup element. CONSTITUTION:A CCD area image sensor 60 and the color separation filter 64 which covers its image pickup surface across an adhesive layer 62 constitute a single plate type color camera. The filter 64 is constituted by arraying primary color filters, i.e. a red filters R, a blue filters B, and a green filters G in a mosaic shape. Here, the primary color filters are superposed on photodetection parts of respective picture elements or opening parts. In this constitution, a light shielding layer 66 is provided among the photodetection parts on the filter 64 by, for example, chromium plating. This layer 66 prevents color mixing between adjacent picture elements through its light shielding operation and increases the quantity of reflected light to the photoelectric converting element 56 for photometry through its reflecting operation to improve the photometric sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a simple and highly sensitive photometric device for an electronic camera having a solid-state image sensor.

(Prior art) Several years ago, images formed by lenses were converted into COD or MO
An electronic still camera that uses a solid-state image pickup device such as S to convert video signals and record them on a small magnetic disk was developed, and since then commercialization has been rapidly progressing. Rewriting records and instant display of images, which was impossible with silver-halide still cameras.

Electronic still cameras are making a big splash in the video field because they enable remote location transmission via cables.

In order for this new still camera to become widespread, the following conditions must be met: high image quality, portability, and economy. In terms of image quality, it is still far ahead of silver-halide still cameras, and improvements in the resolution of the image sensor and signal processing method are needed. In terms of portability, current electronic still cameras are 35mm
It is twice the weight and size of an eye reflex camera, and weighs less than 1 kg.
Considering the emergence of milli-video, it will be necessary to significantly reduce the size and weight in the future. However, there are many systematic difficulties in making electronic still cameras smaller and lighter. In other words, in a silver-halide still camera, the film serves both the imaging and recording functions, whereas in an electronic still camera, the imaging is performed by the image sensor, and the recording is performed by the magnetic disk or semiconductor memory, each of which is responsible for the main function of the camera. The number of parts increases, which in turn increases the size and weight, which also affects the price.

Incidentally, recent cameras are highly automated through electronic control, and in particular, most cameras are equipped with an automatic exposure (AE) mechanism, which is naturally necessary for electronic still cameras as well.

In automatic exposure, ■Measurement of subject brightness, ■Calculation of the aperture value or shutter speed based on the measured value and other setting values, and ■Controlling the aperture or shank speed according to the calculated value are automated. ing.

Regarding measurement of subject brightness (i.e., photometry), conventional electronic still cameras use a beam splitter type that splits a part of the shooting light or finder light with a half mirror and guides it to the light receiving element. .

(Problems to be Solved by the Invention) However, in the case of the beam splitter type, a complicated mechanism is required for the half mirror, which is also a cause of high cost.

In addition, off-axis TTL direct metering is known for conventional silver halide sprue cameras, in which the light that is diffusely reflected on the film surface is picked up by a light receiving element, but this can be applied directly to electronic still cameras. It doesn't work either. That is, the surface of the solid-state image sensor has many specularly reflected components and few diffusely reflected light components, resulting in problems such as low sensitivity and biased photometric distribution.

Therefore, an object of the present invention is to provide a simple and highly sensitive photometry device for an electronic camera that uses a solid-state image sensor.

(Means for solving the problems) First configuration of the present invention that achieves the above object (first invention)
In an electronic camera equipped with a solid-state image sensor that receives light from a subject through an imaging lens and converts it into an electrical video signal, a light-shielding device is installed between the light-receiving parts of each pixel of the color separation filter of the solid-state image sensor. and a photoelectric conversion element that receives the light reflected by the reflection means and generates an electric signal according to the intensity of the subject light.

A second configuration of the present invention that achieves the above object (second invention)
In an electronic camera equipped with a solid-state image sensor that receives light from a subject through an imaging lens and converts it into an electrical video signal, the solid-state image sensor is placed at a distance from the imaging surface of the solid-state image sensor. A glass cap that is attached to the pan cage and has one or more grooves formed on its surface; and a photoelectric conversion device that receives the light reflected by the grooves of the glass cap and generates an electrical signal according to the intensity of the subject light. A third configuration of the present invention (third invention) that achieves the above-mentioned object, characterized by comprising an element.
is an electronic camera equipped with an interline transfer type solid-state image sensor that receives light from a subject through an imaging lens and converts it into an electrical video signal. and a photoelectric conversion element that receives the light reflected by the light reflection means and generates an electrical signal corresponding to the intensity of the object light.

(Function) In the present invention, the first electrical signal obtained by photoelectrically converting the reflected light from the solid-state image sensor provides a photometric value, so it can be said to be a TTL direct photometry method. However, instead of simply using the diffuse reflection component, reflected light is efficiently guided from the solid-state image sensor side to the photoelectric conversion element to obtain high sensitivity.

In the first aspect of the invention, the light-shielding reflecting means includes light (
This reflects the light (which does not contribute to the image) without any waste.

In the second invention, the grooves in the glass cap have a reflective effect. Gap (space) between the glass cap and the imaging surface
As a result, the projected image of the groove on the imaging plane becomes blurred, which does not affect the photographing.

In the third invention, the light reflecting means efficiently and uniformly reflects the light incident on the interline transfer path (which also does not contribute to imaging) from each part of the screen and provides it to the photoelectric conversion element.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1 shows the main structure of an electronic still camera to which the present invention is applied. At the rear of the photographic lens 10, there is a distance of 45 mm with respect to the optical axis.
The half mirror 12 is arranged at an angle, and is driven by a half mirror drive mechanism 36 for quick return operation. The incident light reflected upward by this half mirror 12 is transmitted to the focus plate 14. The condenser lens 16 is guided through the pentaprism 18 and the eyepiece 20 to the optical finder.

An optical low-pass filter 2 is installed behind the half mirror 12.
2 and shutter 24 to CCD or MOS
A solid-state image sensor 26 consisting of the following is arranged. During photographing, when the shutter 24 opens and the half mirror 12 flips up as shown by the dotted line, the subject light that has passed through the photographic lens 10 passes through the optical filter 22 and enters the imaging surface of the solid-state image sensor 26.

In the solid-state image sensor 2e, each pixel generates a signal charge corresponding to the intensity of light and temporarily stores it in a small capacitance.Then, the entire field or frame is successively scanned (transferred) to obtain the object image. An electrical video signal ■S representing the image is output. This video signal VS is supplied to the video signal processing circuit 28 via the preamplifier 27, where it undergoes signal processing such as color correction and modulation. Recording amplifier 30
The data is recorded on the magnetic disk 34 from the magnetic node 32 via the magnetic head 32 .

The magnetic disk 34 is rotated at a constant speed of, for example, 3600 rpm by a spindle motor 36 during photographing. The servo circuit 42 connects the phase generator 38 to the magnetic disk 34.
A PG pulse indicating the rotational phase of the spindle motor 36, a frequency signal indicating the rotational speed of the spindle motor 36 from the frequency generator 38,
Each receives a reference clock signal of approximately 60 Hz from the reference clock generation circuit 44, and controls the rotational speed and phase of the spindle motor 36 in a closed loop. Standard ri o,
The 7-bit generation circuit 44 also supplies clock signals of predetermined frequencies to the arithmetic control section 46 and the image sensor drive circuit 48, respectively. The arithmetic control unit 46 is composed of a microcomputer, and commands disk rotation and image sensor drive during shooting. I] In addition to controlling various parts such as commands, video signal processing systems, Nyanota drive commands, and half mirror drive commands, automatic exposure control is performed as described below.

Now, in this electronic still camera, a photoelectric conversion element 56 for II++ light consisting of, for example, a 5PI) (/recon photo diode) is arranged below the optical low-pass filter 22. Sha when shooting.

9 The drive mechanism 50 operates and the Nyanota 24:)1;
At the same time, when the half mirror 12 flips up, the subject light that has passed through the photographic lens 10 enters the solid-state image sensor 26 via the optical filter 22 as described above. At this time,
According to the present invention, the solid-state image sensor 26 efficiently reflects light, and the reflected light passes through the condensing lens 54 and passes through the photoelectric conversion element 5.
6.

The photoelectric conversion element 56 outputs an electric signal SE having a level corresponding to the intensity of the reflected light incident thereon as a photometric value signal, and this signal SE is converted into a digital signal D by the D/A converter 58.
It is converted into SE and taken into the arithmetic control section 46. The arithmetic control unit 46 time-integrates the photometric value signal at the same time as the start of exposure, and provides a control signal to the shutter drive mechanism 50 to close the shutter 24 when the photometric value signal reaches a predetermined value. In this way, this electronic still camera performs automatic exposure control using TTL direct metering.

Next, a photometric device according to an embodiment of the first invention will be explained with reference to FIGS. 2 and 3. Note that, in FIG. 2, the optical filter 22 . Shutter 24. The condenser lens 54 is omitted, and similar omissions are also made in FIGS. 4 to 7, which will be described later.

In FIG. 2, the COD area image sensor 60
and a color separation filter 64 that is placed on the imaging surface via an adhesive layer 62, forming a single-panel color camera. The color separation filter 64 is made of gelatin, for example,
As shown in Figure 3, red fi/l/9 (R) w I
It consists of primary color filters such as an F filter (B) and a green filter (G) arranged in a mosaic pattern. Here, each primary color filter overlaps the light receiving portion or opening of each pixel. According to this embodiment, a light shielding layer 66 made of, for example, chrome plating is provided above the color separation filter 64 (at the front in FIG. 2) between each primary color filter, and thus between each light receiving section.

The light-shielding layer 66 prevents color mixing between adjacent pixels by its light-shielding effect, and increases the amount of light reflected to the photoelectric conversion element 56 by its reflective effect, thereby increasing photometric sensitivity. Originally, light that enters areas other than the light receiving section does not contribute to imaging, so increasing the amount of reflection of such light does not pose a problem in imaging. Note that the glass M68 above (in front of) the light shielding layer 66 is for protection and is attached to the front surface of the package of the CCD sensor 60.

Note that as a solid-state image sensor, not only CCD but also MO
Of course, other elements such as S and other elements are also possible.

``Salmon 2'' Next, a photometric device according to an embodiment of the second invention will be described with reference to FIG.

In FIG. 4, a glass cap 74 attached to a package 72 in front of the solid-state image sensor 70 serves as a protection as usual, but in this embodiment, as shown in the figure, a thin groove 74a is formed on the surface in the lateral direction. This acts as a reflecting means. That is, the subject light that has passed through the photographic lens 10 and entered the glass cap 74 is reflected by the valley groove 74a and guided to the photoelectric conversion element 56. The number of grooves 74a may be selected appropriately, and the angles of the grooves may be different in the upper and lower parts, or may be the same. This glass cap 74 and the solid-state image sensor 7
A gap 76 is provided between the groove 74a and the groove 74a, which blurs the projected image of the groove 74a on the imaging surface.
does not interfere with shooting.

EXAMPLE Next, a photometric device according to a third embodiment of the invention will be explained with reference to FIGS. 5 to 7. In these figures, 80 is a semiconductor substrate of an interline transfer type CCD image area sensor, 82 is a light receiving section of each pixel, and 84 is an interline transfer COD (generally called a vertical transfer CCD, but in this example, Because it faces in the horizontal direction, it is easy to misunderstand, so it is referred to as above in the present invention.)

First, in the example of FIG. 5, each interline transfer CCD 8
A reflective film having a rough surface, for example, an aluminum film 86, is provided on 4, and the rough surface causes subject light from the photographing lens 10 (not shown) to be diffusely reflected forward, resulting in Almost uniform reflected light is guided to the photoelectric conversion element 56 from various parts of the screen.

In the example shown in FIG. 6, each interline transfer CCD 84 has a metal film 8 on which irregularities are formed at a regular pitch.
8 is provided, which constitutes a reflective diffraction grating. Therefore, the subject light from the photographing lens 10 (not shown) is almost uniformly reflected by each of the diffraction gratings 88 and efficiently guided to the photoelectric conversion element 56.

In the example shown in FIG. 7, a Fresnel mirror 90 made of a metal film is formed on each interline transfer CCD 84, and m photographic object light from the photographing lens 10 (not shown) is reflected almost uniformly by each Fresnel mirror 90. and is efficiently guided to the photoelectric conversion element 56.

In this third embodiment, as in the first embodiment, the reflection of light that enters areas other than the light-receiving area of the pixel (light that does not contribute to photographing) is increased, so there is no problem in photographing. do not have.

Although the preferred embodiments of the present invention have been described above, various modifications and changes are possible. For example, it is also possible to perform multi-pattern photometry by configuring the photoelectric conversion element 56 with a plurality of integrated elements. . Further, the arrangement position of the photoelectric conversion element is not limited to below the optical axis, but can be arranged above or to the side as necessary. Furthermore, the present invention is applicable not only to electronic still cameras (also applicable to video cameras).

(Effects of the Invention) As described above, according to the present invention, by efficiently providing reflected light from a solid-state image sensor to a photoelectric conversion element, it is possible to efficiently provide reflected light from a solid-state image sensor to a photoelectric conversion element without requiring a complicated mechanism (and without causing any hindrance to photographing). Highly sensitive photometry is possible.

Therefore, it is possible to make the electronic camera smaller, l1ffi, or lower in cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main configuration of an electronic still camera to which the present invention is applied; FIG. 2 is a schematic sectional view showing the configuration of a photometric device according to an embodiment of the first invention; FIG. , a schematic plan view showing an example of the arrangement of the light-shielding layer in the photometric device of FIG. 2, FIG. Each figure is a schematic sectional view showing the configuration of a photometric device according to an embodiment of the third invention. 10... Imaging lens, 26... Solid-state image sensor, 56... Photoelectric conversion element, 60... CCD area image sensor, 64... Color separation filter 66... - Light shielding layer, 70... Solid-state image sensor, 74... Glass cap, 74a...
Groove, 76...Gap, 80...Interline transfer type COD image fist area Φ sensor, 82...
··Light receiving section. 84...Interline transfer COD. 86... Aluminum film, 88... Metal film, 90... Fresnel mirror.

Claims (6)

[Claims] (1) In an electronic camera equipped with a solid-state image sensor that receives light from a subject through an imaging lens and converts it into a video signal, each pixel receives light on a color separation filter placed on the imaging surface of the solid-state image sensor. A photometric device comprising: a light-shielding layer provided between the light-shielding layers; and a photoelectric conversion element that receives light reflected by the light-shielding layer and generates an electrical signal according to the intensity of the subject light. . (2) In an electronic camera equipped with a solid-state image sensor that receives light from a subject through an imaging lens and converts it into a video signal, a component that is attached to the package of the solid-state image sensor in front of the solid-state image sensor, and that is attached to the front surface of the solid-state image sensor A glass cap in which one or more grooves are formed; and a photoelectric conversion element that receives light reflected by the grooves of the glass cap and generates an electrical signal according to the intensity of the subject light. A photometric device characterized by: (3) In an electronic camera equipped with an interline transfer type solid-state image sensor that receives light from a subject through an imaging lens and converts it into a video signal, a light reflection device provided on an interline transfer path of the solid-state image sensor A photometric device comprising: means; and a photoelectric conversion element that receives light reflected by the light reflecting means and generates an electrical signal according to the intensity of the object light. (4) The photometric device according to claim 3, wherein the light reflecting means comprises a reflective film with a rough surface. (5) The photometric device according to claim 3, wherein the light reflecting means comprises a Fresnel mirror. (6) The photometric device according to claim 3, wherein the light reflecting means comprises a diffraction grating.