JPH09116807A - Imaging device - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To deepen the depth of field because the optical transfer function is lowered and the resolution is lowered when the diaphragm of the optical system is narrowed down for the purpose of deepening the depth of field. I couldn't do it. SOLUTION: The arrangement position on the optical axis is changed from the focus position within a range in which the range of the depth of field of the image sensor is common to the range of the depth of field of the image sensor 4 arranged at the focus position. An optical block unit including at least one image sensor 5 arranged in a staggered manner, and a high-pass signal component is extracted by a high-pass filter 6 from each output signal of the at least one image sensor 5, and the extracted signal is extracted. The signal processing unit is configured to add the image pickup output signal from the image pickup device 4 arranged at the in-focus position by the adder 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device,
In particular, the present invention relates to an imaging device having a deep depth of field.

[0002]

2. Description of the Related Art Even in an image pickup device for a television,
As with still cameras and movie cameras, the depth of field is increased by narrowing the aperture of the imaging lens.

[0003]

However, when the diaphragm of the image pickup lens is narrowed, the optical transfer function is lowered and the resolution is lowered. In this way, the relationship between the diaphragm of the optical system and the optical transfer function is in a contradictory relationship, and if the diaphragm value (F value) is made small, the depth of field becomes shallow. The depth of field cannot be increased while maintaining the function.

The object of the present invention is to provide a solution to this problem,
An object of the present invention is to provide an imaging device that can obtain a deep depth of field without narrowing the diaphragm of the imaging lens.

[0005]

In order to achieve the above object, the present invention is arranged on the optical axis so that an object existing at a position different from the originally in-focus position in the depth direction can be focused. Image pickup output from the image pickup element placed at the original focus position after the image pickup output signal of the placed image pickup element is passed through a high-pass filter after the position is shifted from the original focus position By adding to the signal, the focus range is expanded (the depth of field is increased). It should be noted that in the above description, two or more image pickup elements may be arranged so as to be displaced from the in-focus position, so that the depth of field can be further increased.

That is, in the image pickup apparatus of the present invention, the arrangement position on the optical axis has a range in which the range of the depth of field of the image pickup element has a common part with the range of the depth of field of the image pickup element arranged at the in-focus position. An optical block unit including at least one image pickup device that is displaced from the in-focus position, and a high frequency signal component is extracted from each output signal of the at least one image pickup device, and the extracted signal is focused. And a signal processing unit for adding to an image pickup output signal from an image pickup element arranged at a position.

In the image pickup apparatus of the present invention, the optical block section has two image pickup elements for green light and one image pickup element for blue light and one image pickup element for red light. Only one of the image pickup devices for green light is arranged such that the arrangement position on the optical axis is displaced from the in-focus position.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments with reference to the accompanying drawings. FIG. 1 shows a first embodiment of the image pickup apparatus of the present invention. In FIG. 1, 1 is a subject, 2 is an imaging lens, 3 is a photolytic prism (two-resolution prism), 4 is an image sensor (I), 5 is an image sensor (II), 6 is a high-pass filter, and 7 is addition. Shows each container.

In order to facilitate understanding, this example is an embodiment in which a monochrome (monochromatic) image pickup device is configured to have a deep depth of field, in which an incident light from a subject 1 is incident. The light first passes through the imaging lens 2 and is then decomposed by the two-resolving prism 3 having a half mirror. Next, the two separated incident lights are received by the two image pickup devices (I) 4 and (II) 5 fixed to the prism 3 via a certain space. Therefore, the image pickup element (I) 4 is fixed to a position on the optical axis where the image of the subject 1 is correctly formed by the image pickup lens 2 and the 2 separation prism 3, and the image pickup element (II) 5 is slightly displaced. It is assumed to be fixed to. This little
It will be understood by the following description with reference to FIGS. 2 and 3.

FIG. 2 shows the operation of the image pickup apparatus of the present invention. FIG. 2 shows the positional relationship between the image pickup device (I) 4 and the image pickup device (II) 5 and the subject 1. The image of the subject is shown on the image pickup device (I) 4 and (II) 5 by the image pickup lens 2. Whether the image is formed (actually, the image is not formed on the image pickup element (II) 5). As described above, the image sensor (I) 4 is arranged so that the image of the subject 1 existing at the position on the optical axis A is correctly formed.
On the other hand, the image sensor (II) 5 is displaced (slightly) from the image sensor (I) 4 by the distance d on the optical axis. Therefore, the subject that forms a correct image on the image sensor (II) 5 is the subject 8 existing at the position on the optical axis B.

Next, the image pickup devices (I) 4 and (II)
Subjects 1 and 8 that form a correct image for each of 5
FIG. 3 shows what the depth of field of FIG. As can be seen from FIG. 3, the depths of field of the subject 1 and the subject 8 are d1a, d1b for the rear depth of field and d2a, d2b for the front depth of field with respect to the positions of A and B on the optical axis, respectively. Is. Therefore, according to the present invention, the rear depth of field d based on the position on the optical axis A is used as a reference.
An image pickup apparatus having a depth of field from the rear end of 1a (the position on the optical axis C) to the front end of the front depth of field d2b (the position on the optical axis D) based on the position on the optical axis B. Can be realized.

In the image pickup apparatus of the present invention, as shown in FIG. 1, the image pickup output signal obtained from the image pickup element (I) 4 is used as a normal image pickup output signal, and the image pickup element (II) 5 is added thereto. Add the high-pass signal component of the imaged output signal obtained from (by high pass filter 6 and adder 7)
Like that. This is because when the entire frequency band component of the image pickup output signal of the image pickup element (II) 5 is added to the image pickup output signal of the image pickup element (I) 4 without passing through the high pass filter 6,
Since the blurred image of the subject A that has not been formed on the image pickup device (II) 5 is overlapped with the image of the subject A that is formed on the image pickup device (I) 4 correctly, a double copy is displayed. Is.
A two-dimensional digital filter or the like can be used as the high pass filter 6.

Furthermore, in realizing the image pickup apparatus of the present invention, it is also related to how far the image pickup element (II) 5 can be displaced from the in-focus position (the position of the image pickup element (I) 4) on the optical axis. As can be seen from FIG. 3, if the displacement distance d of the image sensor 5 is too large, the subjects 1 and 8 are too far apart, and the depth of field regions of both subjects are not continuous.
Specifically, the front end (the position on the optical axis E) of the front depth of field d2a of the subject 1 and the rear depth of field d1b of the subject 8 are determined.
The rear end (position on the optical axis F) of the former is behind the latter (left side in FIG. 3), and a continuous wide depth of field cannot be obtained.

In the above description, the image pickup device (II) 5 for extracting the high-frequency signal component is provided behind the reference image pickup device (I) 4 (on the side far from the image pickup lens 2) on the optical axis, and the image is picked up. The depth of field was increased, but this is also based on another image sensor (I) that takes out another high-frequency signal component.
The depth of field can be made even deeper by providing it in front of 4 (closer to the imaging lens 2). In this case, the incident light is decomposed into three parts by using the three-partitioning prism according to the configuration of FIG. 1, and the three separated parts of the incident light are received by the three image pickup elements fixed to the exit light surfaces of the prisms. To do so.

Finally, as a second embodiment of the image pickup apparatus of the present invention, a case where the image pickup apparatus of the present invention is configured as an image pickup apparatus for a color television will be described with reference to FIG. In FIG. 4, 9 is a photolytic prism (4 resolution prism), 10 to 13 are B (blue), G1 (green I), G2 (green II) and R (red) image pickup devices, and 14 is B, It is a color encoder that converts G and R signals (three primary color signals) into NTSC standard television signals. As shown in the figure, the image pickup output signal from the G2 image pickup element (green II) 12 is passed through a highpass filter 6 to extract a highpass component signal, and the output signal is added by an adder 7 to the G1 image pickup element. (Green I) 11 is added to the image pickup output signal. This makes it possible to obtain a G (green) signal with a deep depth of field,
The depth of field of the luminance signal obtained from the color encoder 14 becomes deep.

Although the present invention has been described above only for the image pickup apparatus using the solid-state image pickup element, the present invention can be applied to the image pickup apparatus using the image pickup tube as it is. .

[0017]

In the past, when the aperture of the optical system was narrowed down for the purpose of deepening the depth of field of the image pickup device, the relation between the aperture of the optical system and the optical transfer function was contradictory, and the aperture value (F value) ) Is small, the depth of field becomes shallow, so it was impossible to deepen the depth of field while maintaining a high optical transfer function. On the other hand, according to the present invention, it is possible to obtain a deep depth of field even when the diaphragm is used in order to maintain a high optical transfer function.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of an image pickup apparatus of the present invention.

FIG. 2 shows the operation of the image pickup apparatus of the present invention.

FIG. 3 shows depths of respective focal depths of two image pickup elements arranged at a focus position and a position other than the focus position.

FIG. 4 shows a second embodiment of the image pickup apparatus of the present invention.

[Explanation of symbols]

 1,8 Subject 2 Imaging lens 3,9 Photolytic prism 4,5,10,11,12,13 Imaging element 6 High-pass filter 7 Adder 14 Color encoder

Claims (2)

[Claims] 1. An arrangement position on the optical axis from a focus position within a range in which the range of the depth of field of the image sensor has a common part with the range of the depth of field of the image sensor arranged at the focus position. An optical block unit including at least one image sensor arranged in a staggered manner, and an image sensor in which a high-frequency signal component is extracted from each output signal of the at least one image sensor and the extracted signal is arranged at a focus position. An image pickup apparatus comprising: a signal processing unit that adds the image pickup output signal from the. 2. The image pickup device according to claim 1, wherein the optical block unit has two green-light image pickup devices and one blue-light image pickup device and one red-light image pickup device.
An image pickup apparatus, wherein only one of the image pickup elements for green light is arranged with its arrangement position on the optical axis shifted from the in-focus position.