JPH07143388A - Video camera - Google Patents

Abstract

PURPOSE:To provide a video camera by which a photographer can recognize focused and non-focused states without losing sight of an object to be photographed. CONSTITUTION:This video camera is constituted so that an image of an object to be photographed, caught by a photographic lens system A is formed by a CCD 8, an output signal of the CCD 8 is processed to a video signal by a video signal processing circuit 11, this video signal is stored in a field memory 14, and also, the video signal is detected by a video signal detector 13 and a contrast value signal is obtained, and from a variation of the contrast value signal caused by a movement of a focus lens 2 in the optical axis direction, a direction of focusing and a degree of focusing are calculated by a microcomputer 5, and in accordance with focusing, non-focusing and the degree of non- focusing, the video signal in the field memory 14 is subjected to image processing by a memory controller 15, and the object image subjected to image processing is displayed on an electronic viewer 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera having an electronic viewfinder (hereinafter abbreviated as EVF).

[0002]

2. Description of the Related Art Recently, a video camera equipped with an EVF is in the mainstream. However, the EVF of a video camera has a small screen size and insufficient resolution, so that the photographer cannot use the EVF.
It was difficult to focus with high precision while watching the display. Therefore, a system in which a focusing / non-focusing determination unit is provided on the camera side and is displayed on the EVF display screen becomes effective.

[0003]

EVF of video camera
As a means for displaying the in-focus and out-of-focus information, for example, by using a character generator, LEDs, etc., which are generally used in film cameras and the like, the in-focus direction and the in-focus state can be set at the top, bottom, left and right edges of the screen. The display method is generally used. But,
In this method, when the photographer focuses on the subject, the focus display is distracted, and it is difficult to concentrate on the subject image.

The present invention has been made based on such a background, and provides a video camera which enables a photographer to recognize the in-focus state and the out-of-focus state without looking away from the subject image. With the goal.

[0005]

In order to achieve the above object, the present invention provides a photographing lens system having a variable imaging position, and a photoelectric conversion element on which a subject image captured by the photographing lens system is formed. A video signal generating means for generating a video signal of the subject image from the output signal of the photoelectric conversion element; a focus detection means for detecting a focus state of the subject image formed on the photoelectric conversion element; Based on the detection result of the focus detection means, an image processing means for image-processing the video signal according to the degree of focus, out-of-focus, and out-of-focus of the subject image, and image processing by the image processing means. An electronic viewfinder for displaying the subject image after image processing based on the image signal thus obtained.

Further, according to the present invention, the photographing lens system has a focus lens, and is further provided with an operation member for changing an image forming position of the focus lens by a manual operation. Furthermore, the present invention further comprises signal detection means for detecting the contrast value of the video signal, and the focus detection means detects the focus state based on the contrast value.

[0007]

According to the present invention, the image signal obtained from the output signal of the photoelectric conversion element on which the subject image is formed is subjected to image processing in accordance with the focus of the subject image, defocus, and the degree of defocus. Since the subject image after image processing is displayed on the electronic viewfinder, just looking at the image displayed on the electronic viewfinder without looking away from the subject image allows the subject image to be in focus, out of focus, or out of focus. It is possible to easily recognize the degree of the front focus (in a state in which a portion in front of the subject is in focus) and the rear focus (in a state in rear of the subject are in focus) when focused. In the case where an operation member for manually changing the image forming position of the focus lens in the photographing lens system is provided, the focusing operation by the operation of the operation member can be performed reliably and quickly. Further, the focus detection means is
The focus state may be detected by comparing the measurement result of the distance to the object by the light wave distance measuring means, which is generally used in film cameras, with the current image forming position of the focus lens, or the video signal. The in-focus state may be detected based on the contrast value of.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a video camera according to an embodiment. In the figure, 1 is a manual focus ring (corresponding to an operating member), 2 is a focus lens, 3 is a lens barrel, the focus lens 2 is held by the lens barrel 3 so as to be movable in the optical axis direction, and the manual focus ring 1 is It is rotatably fitted in the lens barrel 3. Further, in the figure, 4 is a focus ring counter for detecting the rotation direction, the number of rotations, and the rotation speed of the manual focus ring 1, and 5 is the input of the output of the focus ring counter 4 to the input terminal IP1.
The microcomputer 7 outputs commands from the focus driver 6 to the focus driver 6, and the focus motor 7 is driven by the focus driver 6 to move the focus lens 2.

In the video camera of this embodiment, when the photographer rotates the manual focus ring 1 and the rotation direction, the number of rotations, and the rotation speed are detected by the focus ring counter 4, the focus is controlled by the microcomputer 5. The focus motor 7 is driven by the driver 6, the focus lens 2 is moved in the optical axis direction, and the imaging position is changed. In the figure, A indicates a taking lens system, and the taking lens system A includes a zoom lens and the like in addition to the focus lens 2.

Reference numeral 8 denotes a CCD (corresponding to a photoelectric conversion element) on which a subject image captured by the focus lens 2 is formed.
The S / H (sampling hold) / AGC (auto gain control) unit 9, A /
A D converter 10, a video signal processing circuit 11 (corresponding to a video signal generating means), and a first D / A converter 12 are arranged in this order. The video signal from the video signal processing circuit 11 is also sent to the video signal detector 13 (corresponding to signal detecting means) and the field memory 14. The contrast signal output from the video signal detector 13 is input to the input terminal IP of the microcomputer 5.
It is designed to be included in 2.

Output terminal OP2 of the microcomputer 5
From the above, a command is output to a memory controller 15 (corresponding to an image processing means) which controls the field memory 14, and the field memory 1
The processed video signal, which will be described later, from the encoder 4 is the encoder 1
6 and the second D / A converter 17, and is sent to the EVF 18 as a monitor output.

By the way, the value of the contrast signal is
As shown in FIG. 2, it becomes the maximum value when focusing. When the focus lens 2 is moved in the out-of-focus state, the contrast value increases when approaching the in-focus point and decreases when approaching the in-focus point. Therefore, the focus direction can be known by observing the change in the contrast value. Further, in the vicinity of the focus point, the change in the contrast value when the focus lens 2 is moved minutely becomes smaller toward the focus point, so that the degree of focus can be known.

Based on this, the operation of the system shown in FIG. 1 will be described below. Manual focus ring 1
When is rotated by the photographer, the focus ring counter 4 detects the rotation direction, the number of rotations, and the rotation speed, and inputs a detection signal to the microcomputer 5. Then, the microcomputer 5 drives the focus motor 7 via the focus driver 6 according to the signal, whereby the focus lens 2 is moved along the optical axis direction to the front or rear of the lens barrel 3 by a predetermined distance. Be done.

A subject image captured by the photographing lens system A and passing through the focus lens 2 is imaged on the surface of the CCD 8 and photoelectrically converted, and is passed through the S / H / AGC section 9 to A
A / D conversion is performed by the / D converter 10, and the result is sent to the video signal processing circuit 11. The video signal from the video signal processing circuit 11 is the first D / A converter 12, the video signal detector 13,
It is sent to the field memory 14. Then, the video signal from the video signal processing circuit 11 through the first D / A converter 12 becomes a video output.

The video signal detector 13 detects a high frequency component from the video signal and outputs a contrast value signal. This contrast value signal is input to the input terminal IP2 of the microcomputer 5.

Next, the processing of the microcomputer 5 will be described. A signal for moving the lens from the focus ring counter 4 is input to the microcomputer 5, and a contrast value signal from the video signal detector 13 is input to the microcomputer 5.
Calculates the direction of focus and the degree of focus by grasping the amount of change in the contrast value due to the minute movement of the focus lens 2 based on these data.

Specifically, the front pin (a state in which a portion on the front side of the subject is in focus) and the rear pin (a state in which a portion on the rear side of the subject is in focus) are determined. Based on this result, the microcomputer 5 determines how to process the video signal data stored in the field memory 14, and sends the information from the output terminal OP2 to the memory controller 15.

The video signal of the field memory 14 processed by the memory controller 15 is the encoder 1
6 and the second D / A converter 17 to become an EVF monitor output. The photographer can know the degree of focus by viewing the video signal processed according to the degree of focus through the EVF.

A specific example of video signal processing will be described below. The video signal is processed as follows depending on the degree of focusing. (1) Blurring the entire screen or a part (for example, the central part). In this case, the degree of focus can be determined by changing the degree of blurring or changing the size of the blurring range. Also, when blurring a part, changing the shape of the blurring area
The rear pin can be identified. (2) A mosaic is applied to the whole screen or a part of it. (3) Shift the center of the screen into a strip. In this case, it is possible to distinguish between the front pin and the rear pin depending on the shifting direction. (4) Change the brightness of the whole screen or a part thereof. This method is effective when the subject is in a place with low illuminance. (5) Rotate and display a part of the screen. In this case, the front pin and the rear pin can be discriminated by the rotation direction. (6) Display dots on the entire screen or a part of the screen. in this case,
The degree of focus can be determined by the number of points or the size of the points. (7) The level difference between the luminance signals of the whole screen or a part of the screen is reduced. As a result, the contrast of the image can be reduced while leaving the edges of the subject.

The present invention can be applied to all video cameras equipped with an electronic viewfinder regardless of the presence or absence of image recording means, and can of course be applied to still video cameras.

[0021]

As described above, according to the present invention, the video signal is image-processed according to the degree of focusing and non-focusing, and E
Since the photographer can see the processed image through the VF, the photographer can accurately recognize the in-focus state and the in-focus state without losing the subject.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a video camera according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram of a contrast value depending on a focus lens position.

[Explanation of symbols]

 A shooting lens system 1 manual focus ring (operation member) 2 focus lens 8 CCD (photoelectric conversion element) 11 video signal processing circuit (video signal generation means) 13 video signal detector (signal detection means) 15 memory controller (image processing means) ) 18 Electronic viewfinder (EVF)

Claims (3)

[Claims] 1. A photographing lens system having a variable image forming position, a photoelectric conversion element on which a subject image captured by the photographing lens system is formed, and a video signal of the subject image is generated from an output signal of the photoelectric conversion element. Image signal generating means, focus detecting means for detecting a focus state of the subject image formed on the photoelectric conversion element, and focusing of the subject image based on a detection result of the focus detecting means. , Out-of-focus, and image processing means for image-processing the video signal according to the degree of out-of-focus, and the subject image after image processing is displayed based on the video signal image-processed by the image processing means. An electronic viewfinder that is equipped with a video camera. 2. The video camera according to claim 1, wherein the taking lens system has a focus lens, and further comprises an operation member for changing an image forming position of the focus lens by a manual operation. 3. The video camera according to claim 1, further comprising signal detection means for detecting a contrast value of the video signal, wherein the focus detection means detects a focus state based on the contrast value.