JP2002281375A - Electronic camera and image display method in the case of automatic focus adjustment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm a state of focusing and a photographing angle by displaying a moving picture in the case of focusing based on an image signal to be obtained from an image pickup device, and to switch to a still image or a monochromatic image when a defect is found in the display of the moving picture. SOLUTION: Focus adjustment is automatically performed based on an image signal to be obtained from a CCD and an image of a subject is displayed. When the image of the subject is displayed in the case of the automatic focus adjustment, brightness of the subject is detected and shutter speed and a pixel mixture mode of the CCD in the case of the automatic focus control are determined (steps S10, S12). When the shutter speed is equal to or more than a prescribed value S corresponding to brightness of the subject by which smear is conspicuous, the object image determined to be a still image (a step S16), when the pixel mixture mode in which colors are mixed is selected, the object image is determined to be a still image or monochromatic animation (a step S24) and when the display is in the case except them, it is determined to be a colored moving picture (a step S22).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera and an image display method at the time of automatic focus adjustment. The present invention relates to an electronic camera for displaying an image of the same type and an image display method at the time of automatic focusing.

[0002]

2. Description of the Related Art In general, in automatic focus adjustment in an electronic camera, an image is taken while moving a focus lens of a photographic optical system which acts on focus adjustment, and a high-frequency component is extracted from an output image signal to focus. Calculate the evaluation value for
The focus lens is moved to a position where the evaluation value is maximized to focus.

Further, as an image display method for displaying an image on a liquid crystal monitor of an electronic camera during the automatic focus adjustment, a method for displaying a moving image based on an image signal output from an image pickup device, and a method disclosed in Japanese Patent Application Laid-Open No. H10-294889. There is a method of displaying an image immediately before moving a focus lens as a still image, as described in Japanese Patent Application Laid-Open No. H10-260, 1988.

[0004]

In the case of confirming the focus with an electronic viewfinder (LCD, EDF, etc.) of an electronic camera, it is difficult to follow a subject if a still image is displayed during automatic focus adjustment. This makes it difficult to shoot at the angle of view desired by the photographer. Therefore, it is desirable to drive the focus lens at the time of automatic focus adjustment and display a state of focusing as a moving image.

On the other hand, when displaying a moving image at the time of automatic focus adjustment, it is necessary to obtain an image signal for outputting the moving image to the liquid crystal monitor. It does not always match the image signal required for output.

That is, the image pickup device used in recent electronic cameras tends to have a large number of pixels, and there are several million pixels. However, an image pickup device having a high number of pixels is used and the speed of focus adjustment is increased. In order to achieve this, it is necessary to thin out and read out information (charge) of pixels in the vertical direction of the image sensor. In addition, when the brightness of the subject is low at the time of automatic focus adjustment, in order to obtain a good evaluation value, the charge of several pixels in the vertical direction of the image sensor is mixed, but depending on the number of pixels to be mixed, In some cases, different color information may be mixed, and in this case, there is a problem that a moving image displayed on a liquid crystal monitor is difficult to see.

When there is a high-luminance subject, smear is mixed in the vertical transfer path of the image sensor. If the charge of pixels in the vertical direction is read out from the image sensor and read out, the charge on the pixels is thinned out, but smears are added without being thinned out. There is a problem that smear is noticeable in the displayed video.

The present invention has been made in view of such circumstances, and when performing automatic focus adjustment based on an image signal obtained from an image sensor, a state in which a moving image is displayed to achieve focusing. It is an object of the present invention to provide an electronic camera capable of checking the angle of view and the angle of view, and switching to a still image or a monochrome moving image when a problem occurs in displaying a moving image, and an image display method during automatic focus adjustment.

[0009]

According to a first aspect of the present invention, there is provided an electronic camera having a plurality of operation modes for driving an image pickup device.
Operating mode determining means for determining one of the operation modes, image signal obtaining means for driving the image sensor in the operation mode determined by the operation mode determining means to obtain an image signal, and image signal obtaining means for obtaining the image signal. Automatic focus adjustment means for automatically performing focus adjustment based on an image signal; display means for displaying a moving image or a still image based on the image signal acquired by the image signal acquisition means; and operation mode decision means. Switching means for switching an image displayed on the display means to a moving image or a still image according to the operation mode.

An electronic camera according to a second aspect of the present invention has a plurality of operation modes for driving an image pickup device, an operation mode determination means for determining one operation mode from the plurality of operation modes, and the operation mode determination means. Image signal obtaining means for driving the image sensor in the operation mode determined by the image signal to obtain an image signal, and automatic focus adjustment means for automatically performing focus adjustment based on the image signal obtained by the image signal obtaining means A display unit that displays a color moving image or a monochrome moving image based on the image signal acquired by the image signal acquiring unit; and an image displayed on the display unit according to the operation mode determined by the operation mode determining unit. Or switching means for switching to a monochrome moving image.

That is, depending on the operation mode of the image sensor at the time of automatic focus adjustment, there is a case where a good moving image cannot be displayed on the basis of the image signal acquired in the operation mode. An image or a monochrome moving image is displayed.

[0012] As set forth in claim 3 of the present application, there is provided detecting means for detecting the brightness of the subject, and the operation mode determining means is adapted to detect the brightness of the subject by the plurality of operating modes in accordance with the brightness of the subject detected by the detecting means. To determine one operation mode.

As described in claim 4 of the present application, the image pickup device has a color filter in which horizontal lines have the same color arrangement every other line, and the plurality of operation modes are 2n (where n is 2) from the image pickup device. 1 for each line)
A mode for reading the image signal of the line, wherein
By mixing information of n or less pixels in the vertical direction of the line, 1
A first pixel mixing mode for reading an image signal of a line,
A second pixel mixing mode in which information of more than n pixels in the 2n lines in the vertical direction are mixed and read out as an image signal of one line, and the operation mode determination means is detected by the detection means. The pixel mixing mode in which the number of pixels to be mixed is larger as the brightness of the subject is lower, and the switching unit causes the display unit to display when the first pixel mixing mode is determined by the operation mode determining unit. The image is switched to a moving image, and when the second mixed mode is determined, the image displayed on the display unit is switched to a still image.

That is, when the first pixel mixing mode is used as the operation mode of the image pickup device depending on the brightness of the subject, color information is not mixed by the pixel mixing, so that a moving image is displayed. When the second pixel mixing mode is used, a color image is mixed due to the pixel mixing, so that a still image is displayed.

As described in claim 5 of the present application, the image pickup device has a color filter in which horizontal lines have the same color arrangement every other line, and the plurality of operation modes are 2n (where n is 2) from the image pickup device. 1 for each line)
A mode for reading the image signal of the line, wherein
By mixing information of n or less pixels in the vertical direction of the line, 1
A first pixel mixing mode for reading an image signal of a line,
A second pixel mixing mode in which information of more than n pixels in the 2n lines in the vertical direction are mixed and read out as an image signal of one line, and the operation mode determination means is detected by the detection means. The pixel mixing mode in which the number of pixels to be mixed is larger as the brightness of the subject is lower, and the switching unit causes the display unit to display when the first pixel mixing mode is determined by the operation mode determining unit. The image is switched to a color moving image, and when the second mixed mode is determined, the image displayed on the display unit is switched to a monochrome moving image.

That is, when the first pixel mixing mode is used as the operation mode of the image sensor depending on the brightness of the subject, color information is not mixed due to the pixel mixing, so that a color moving image is displayed. When the second pixel mixing mode is used, the monochrome information is displayed because the color information is mixed by the pixel mixing.

According to a sixth aspect of the present invention, there is provided an electronic camera, comprising: an image signal acquiring unit that drives an image sensor to acquire an image signal;
An automatic focus adjustment unit that automatically performs focus adjustment based on the image signal acquired by the image signal acquisition unit; and a display unit that displays a moving image or a still image based on the image signal acquired by the image signal acquisition unit. Detecting means for detecting the brightness of the subject, and switching means for switching an image displayed on the display means to a moving image or a still image in accordance with the brightness of the subject detected by the detecting means. I have.

That is, depending on the brightness of the subject at the time of automatic focus adjustment, there is a case where a good moving image cannot be displayed based on the image signal acquired at that time. In this case, a still image is displayed instead of the moving image. I am trying to do it.

As set forth in claim 7 of the present application, when the brightness of the subject detected by the detection means is equal to or higher than a predetermined brightness at which smear is conspicuous in an image displayed on the display means, It is characterized in that the image displayed on the display means is switched to a still image.

[0020] As described in claim 8 of the present application, the image signal acquisition means thins out and reads out information of pixels in the vertical direction of the image pickup element at the time of focus adjustment by the automatic focus adjustment means.

According to a ninth aspect of the present invention, there is provided an image display method at the time of automatic focus adjustment for automatically performing focus adjustment based on an image signal obtained from an image sensor and displaying an image of the subject. Detecting the brightness of the subject, switching the operation mode of the image sensor at the time of automatic focus adjustment depending on whether the detected brightness of the subject is brighter than the first brightness, and Automatically adjusting the focus based on the image signal obtained from the image sensor, and obtaining the brightness of the detected subject from the image sensor during the automatic focus adjustment when the detected brightness is brighter than the first brightness. Displaying a moving image based on the detected image signal; and, when the brightness of the detected subject is lower than the first brightness, And displaying a still image based on the image signal acquired from the imaging device to the point regulation immediately before,
It is characterized by including.

According to a tenth aspect of the present invention, there is provided an image display method at the time of automatic focus adjustment for automatically performing focus adjustment based on an image signal obtained from an image sensor and displaying an image of the subject. Detecting the brightness of the subject, switching the operation mode of the image sensor at the time of automatic focus adjustment depending on whether the detected brightness of the subject is brighter than the first brightness, and Automatically adjusting the focus based on the image signal obtained from the image sensor, and obtaining the brightness of the detected subject from the image sensor during the automatic focus adjustment when the detected brightness is brighter than the first brightness. Displaying a color moving image based on the obtained image signal;
Displaying the monochrome moving image based on an image signal obtained from the image sensor during the automatic focusing when the detected brightness of the subject is lower than the first brightness. Features.

That is, the operation mode of the image pickup device is switched depending on whether at least the brightness of the subject is higher than the first brightness. If the brightness of the subject at the time of the automatic focus adjustment is lower than the first brightness, the moving image based on the image signal acquired by the operation mode at that time is not displayed, and the image pickup device immediately before the automatic focus adjustment is performed. A still image is displayed based on an image signal acquired from the camera, or a monochrome moving image is displayed based on an image signal acquired at the time of automatic focus adjustment.

As described in claim 11 of the present application, the image pickup device has a color filter in which horizontal lines have the same color arrangement every other line, and the operation mode of the image pickup device is as follows.
A mode in which one line of an image signal is read out for every 2n (n is an integer of 2 or more) lines from the image sensor;
A first pixel mixing mode in which information of n or less pixels in the vertical direction of n lines are mixed to read out an image signal of one line, and information of more than n pixels in the vertical direction of the 2n lines are mixed. Read out as a one-line image signal
Wherein the step of switching the operation mode includes the step of switching to the first pixel mixing mode when the brightness of the detected subject during the automatic focus adjustment is brighter than the first brightness. When the brightness is lower than the first brightness, the mode is switched to the second pixel mixing mode.

That is, the first pixel mixing mode or the second pixel mixing mode is used as the operation mode of the image pickup device depending on whether the brightness of the subject is higher than the first brightness. Then, when the first pixel mixing mode is used, since the color information is not mixed due to the pixel mixing, a moving image is displayed based on the image signal acquired in the first pixel mixing mode. When the pixel mixing mode of 2 is used, since color information is mixed by the pixel mixing, a still image is displayed based on the image signal obtained from the image sensor immediately before the automatic focus adjustment, or at the time of the automatic focus adjustment. A monochrome moving image is displayed based on the acquired image signal.

According to a twelfth aspect of the present invention, in an image display method at the time of automatic focus adjustment for automatically performing focus adjustment based on an image signal obtained from an image pickup device and displaying an image of the subject, Detecting, and automatically performing focus adjustment based on an image signal obtained from the image sensor at the time of automatic focus adjustment, and when the detected brightness of the subject is equal to or greater than a second brightness. Displaying a still image based on an image signal obtained from an image sensor immediately before the automatic focus adjustment, and when the detected brightness of the subject is lower than the second brightness, Displaying a moving image based on the image signal acquired from the image sensor during the adjustment.

That is, depending on the brightness of the subject at the time of the automatic focus adjustment, there is a case where a good moving image cannot be displayed based on the image signal acquired at that time. In this case, a still image is displayed instead of the moving image. I am trying to do it.

When the detected brightness of the subject is equal to or higher than the second brightness, the operation mode of the image sensor is determined by the information of the pixel in the vertical direction from the image sensor. A thinning mode in which the smear is noticeable when a moving image is displayed based on an image signal obtained from the image sensor during the automatic focus adjustment. And

That is, depending on the brightness of the subject at the time of automatic focus adjustment, there is a case where a good moving image cannot be displayed on the basis of the image signal acquired at that time due to the occurrence of smear. A still image is displayed.

The invention according to claim 1 or 2 and claim 6
The invention according to claim 9 or 10 may be combined.
And the invention according to claim 12 may be combined.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an electronic camera and an image display method at the time of automatic focusing according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an external view of an electronic camera according to the present invention. A photographing lens 1 is provided on the front of the electronic camera 10.
2. A finder window 14 and a strobe light emitting section 16 are provided, and a shutter button 18 and a power switch 20 are provided on the upper surface of the camera. A card slot 26 for mounting a memory card 24 is provided on the side of the camera opposite to the grip 22.

A zoom lens is applied to the photographing lens 12, and a CCD color image sensor having several million pixels (not shown in FIG. 1 and denoted by reference numeral 52 in FIG. 3) is provided behind the photographing lens 12 as an image sensor. Are located. The shutter button 18 is configured in a two-stage manner, and in a state of “half-pressing” in which the shutter button 18 is lightly pressed to stop, the automatic focus adjustment (AF) and the automatic exposure control (AE) are activated to lock the AF and AE, and “ Shooting is performed in a state of “full press” from “half press” to further press.

The power switch 20 is also used as a mode changeover switch.
"Shooting ON position" which is turned on in still image shooting mode,
And the "reproduction ON position" which is turned on in the reproduction mode.
The position can be switched. In place of the power switch (hereinafter, referred to as a power / mode switch) 20 as in the present embodiment, a power switch for only power ON / OFF and a mode switching means such as a mode dial for switching between a still image shooting mode and a reproduction mode. May be provided.

FIG. 2 is an external view of the back side of the electronic camera 10. On the back of the electronic camera 10, a finder 28, a liquid crystal monitor 30, a zoom switch 32, a multifunctional cross button 34, an AE lock button 36, a menu key 38, an execution key 40, and a cancel key 42 are provided.
The liquid crystal monitor 30 is a display means that can be used as an electronic finder for confirming the angle of view during photographing, and can display a preview image of a photographed image, a reproduced image read from the memory card 24, and the like. Selection of menus using the cross button 34 and setting of various items in each menu are also performed using the display screen of the liquid crystal monitor 30.

The zoom switch 32 is composed of a lever switch which can be operated in the up and down direction. The switch is operated to perform a zoom movement in a telephoto (TELE) direction by operating the switch upward, and a wide angle (WIDE) by operating the switch downward. ) Zoom in the direction. The cross button 34 is pressed in one of four directions (up, down, left,
The right button allows the user to input instructions, and is used as an operation button to select various setting items on the menu screen or to change the settings, and to adjust the electronic zoom magnification and to forward / return the playback frame. It is used as an instruction means.

The menu key 38 is used to make a transition from the normal screen of each mode to the menu screen. The execution key 40 is used, for example, when confirming the selected contents or instructing execution (confirmation) of processing. The cancel key 42 is used to cancel (cancel) an item selected from the menu or to return to the previous operation state.

The photographer operates the zoom switch 32 to determine the angle of view while checking the image (through image) displayed on the viewfinder 28 or the liquid crystal monitor 30, and presses the shutter button 18 to perform photographing.

FIG. 3 is a block diagram showing the internal configuration of the electronic camera 10. The taking lens 12 includes a fixed lens 44,
The zoom lens includes a four-group inner focus zoom lens including a variable power lens 46A, a correction lens 46B, and a focus lens 48.

The variable power lens 46A and the correction lens 46B
The camera moves along the optical axis while the positional relationship between the two is regulated by a cam mechanism (not shown), and changes the focal length. For convenience of explanation, a variable power optical system including a variable power lens 46A and a correction lens 46B will be referred to as a "zoom lens 46".

The light that has passed through the taking lens 12 is
After the light amount is adjusted, the light enters a CCD image sensor (hereinafter, referred to as CCD) 52. This CCD 52
Is provided with a color filter having a G stripe arrangement as shown in FIG. The color filter of the G stripe arrangement has a filter arrangement of GRGBGRG... In the horizontal direction, the G filters are arranged in the vertical direction, and the same filter arrangement is provided every other line (odd lines or even lines). I have. In this embodiment, the aperture 50 has an F number of F = 2.8, 8 (AV
(Aperture value) = 3, 6) can be used.

Photo sensors are arranged in a plane on the light receiving surface of the CCD 52.
The subject image formed on the light receiving surface of D52 is converted by each photosensor into signal charges of an amount corresponding to the amount of incident light. Note that the CCD 52 has a so-called electronic shutter function of controlling the charge accumulation time (shutter speed) of each photosensor by the timing of a shutter gate pulse.

The signal charges accumulated in each photo sensor are:
The signals are sequentially read out as voltage signals (image signals) corresponding to the signal charges based on the pulses supplied from the CCD driver 54. The image signal output from the CCD 52 is sent to the analog processing unit 56. The analog processing unit 56 includes a signal processing circuit such as a sampling hold circuit, a color separation circuit, and a gain adjustment circuit. In the analog processing unit 56, correlated double sampling (CDS) processing,
Each of the G and B color signals is subjected to color separation processing, and the signal level of each color signal is adjusted (pre-white balance processing).

The signal output from the analog processing section 56 is converted into a digital signal by the A / D converter 58 and stored in the memory 60. The timing generator (TG) 62 gives a timing signal to the CCD driver 54, the analog processing unit 56, and the A / D converter 58 in accordance with a command from the CPU 64, and the circuits are synchronized by the timing signal. . TG6
Reference numeral 2 denotes a timing signal for driving the CCD 52 in a different operation mode at the time of shutter release, at the time of outputting a through image, and at the time of automatic focus adjustment.
, And outputs a timing pulse for driving the CCD 52 in different operation modes according to the brightness of the subject even during automatic focus adjustment. The details of each operation mode of the CCD 52 during the automatic focus adjustment will be described later.

The data stored in the memory 60 is transmitted to the bus 6
6 to the signal processing section 68. Signal processing unit 68
Is a digital signal processor (D) including a luminance / color difference signal generation circuit, a gamma correction circuit, a sharpness correction circuit, a contrast correction circuit, a white balance correction circuit, and the like.
SP), and processes an image signal in accordance with a command from the CPU 64.

The image data input to the signal processing unit 68 includes a luminance signal (Y signal) and color difference signals (Cr, Cb signals).
After being converted to, and subjected to predetermined processing such as gamma correction, the data is stored in the memory 60. When displaying the captured image, the image data is read from the memory 60,
The data is transferred to the display memory 70. The data stored in the display memory 70 is a signal of a predetermined system for display (for example,
After being converted to an NTSC color composite video signal)
The data is output to the liquid crystal monitor (LCD) 30 via the D / A converter 72. Thus, the image content of the image data is displayed on the screen of the liquid crystal monitor 30.

The image data in the memory 60 is periodically rewritten by the image signal output from the CCD 52,
The video signal generated from the image data is transmitted to the liquid crystal monitor 3
By being supplied to 0, an image input via the CCD 52 is displayed on the liquid crystal monitor 30 in real time.
The photographer can check the photographing angle of view using the image (through image) displayed on the liquid crystal monitor 30 or the optical viewfinder 28.

When the photographer operates the zoom switch 32, an instruction signal is input to the CPU 64,
Controls the zoom drive unit 74 based on the signal from the zoom switch 32 to move the zoom lens 46 in the tele (TELE) direction or the wide (WIDE) direction. Zoom drive 7
Reference numeral 4 includes a motor (not shown), and the zoom lens 46 is driven by the driving force of the motor. The position (zoom position) of the zoom lens 46 is detected by a zoom position sensor 76, and a detection signal from the sensor 76 is input to the CPU 64.

Similarly, the focus driving section 78 includes a motor (not shown), and the focus lens 48 moves back and forth along the optical axis by the driving force of the motor. The position of the focus lens 48 (focus position) is detected by a focus position sensor 80, and the detection signal of the sensor 80 is C
It is input to PU64.

When the still image photographing mode is set by the power / mode switch 20 and the shutter button 18 is pressed, a photographing start instruction (release ON) signal is issued. The CPU 64 detects a release ON signal and executes an imaging operation for recording. That is, the CPU 64 controls the focus driving unit 78 to move the focus lens 48 to the in-focus position based on the result of the evaluation value calculation described later, and controls the aperture diameter of the diaphragm 50 and the electronic shutter of the CCD 52 by controlling the aperture. Perform exposure control. Also, CP
The U 64 sends a command to the strobe control circuit 82 as needed to control the light emission of the strobe light emitting unit 16.

In this manner, in response to the pressing operation of the shutter button 18, the capture of the image data for recording is started. When the mode for compressing and recording image data is selected, the CPU 64 sends a command to the compression / expansion circuit 84. The compression / expansion circuit 84 compresses the image data taken into the memory 60 according to JPEG or another predetermined format.

The compressed image data is recorded on the memory card 24 via the card interface 86.
Mode for recording uncompressed image data (uncompressed mode)
Is selected, the compression processing by the compression / expansion circuit 84 is omitted, and the image data is recorded on the memory card 24 without being compressed.

In the electronic camera 10 of the present embodiment, for example, smart media (Solid-
State Floppy Disk Card) is applied. The form of the recording medium is not limited to this, and may be a PC card, a compact flash (registered trademark), a magnetic disk, an optical disk, a magneto-optical disk, a memory stick, or the like, and may be electronic, magnetic, optical, or a combination thereof. Various readable and writable media can be used according to the method described in the above. Signal processing means and interfaces corresponding to the medium used are applied. A configuration may be adopted in which a plurality of media can be mounted irrespective of different types or the same type of recording media. The means for saving the image file is not limited to a removable medium that can be attached to and detached from the camera body, but may be a recording medium (internal memory) built in the electronic camera 10.

When the reproduction mode is set by the power / mode switch 20, an image file is read from the memory card 24. The read image data is expanded by a compression / expansion circuit 84 as necessary, and output to the liquid crystal monitor 30 via the display memory 70.

The CPU 64 is a control section for controlling the circuits of the camera system. The CPU 64 controls the operation of the corresponding circuit based on input signals received from the power / mode switch 20, the shutter button 18, the zoom switch 32, and other operation units, and controls display on the liquid crystal monitor 30, automatic focus (AF). Adjustment and automatic exposure (AE) control are performed.

Here, the AF adjustment will be described.

When the shutter button 18 is half-pressed,
The image signal converted into a digital signal by the A / D converter 58 is input to the evaluation value calculation unit 88. The evaluation value calculation unit 88 has a high frequency component extraction circuit 90 and an integration circuit 92. The evaluation value calculation unit 88 samples the G component data from the input image signal to extract the high frequency component in the AF detection target area and to extract its absolute value. Value obtained by integrating the absolute value data within the AF detection target area (corresponding to the evaluation value)
Is provided to the CPU 64.

The target area for AF detection need not be the entire image area, but is set as a partial area at the center of the image. During the AF operation, the CPU 64 detects the contrast of the central part of the image at a plurality of AF detection points (search points) while moving the focus lens 48 from infinity to near (or from close to infinity) in the focus adjustment area. , An evaluation value is calculated. Then, the evaluation value calculated at each point is integrated, the lens position having the maximum evaluation value is determined as the focus position, and the focus driving unit 78 is moved to move the focus lens 48 to the obtained focus position. Control and perform auto focus.

Thereafter, when the CPU 64 confirms that the shutter button 18 is fully pressed, the subject is imaged at the current zoom position and the focused focus position, and the image data that has undergone predetermined signal processing is stored in the memory card together with the accessory information. 24.

Next, the CCD 52 in the above-mentioned AF adjustment is used.
The operation mode and the display image on the liquid crystal monitor 30 will be described.

When displaying a through image on the liquid crystal monitor 30, the CCD 52 is driven in a quarter thinning mode for reading out one line of image signal every four lines. still,
Even if the liquid crystal monitor 30 is driven in the thinning mode, the quality of the through image displayed on the liquid crystal monitor 30 does not deteriorate. This is because the number of pixels of the CCD 52 is much larger than the number of pixels of the liquid crystal monitor 30.

At the time of AF adjustment, the CCD 52 is driven in an operation mode in which one line of an image signal is read out every eight lines. This is to increase the reading speed of the image signal from the CCD 52 during the AF adjustment.

The operation mode of the CCD 52 at the time of the AF adjustment is a two-pixel mixing mode, a four-pixel mixing mode, or an eight-pixel mixing mode according to the brightness of the subject as shown in the AF detection exposure program diagram shown in FIG. used.

That is, as shown in FIG. 5, when the brightness of the subject is 8 EV (exposure value) or more, 2
The pixel mixing mode is used. If the EV is 7 EV or more and less than 8 EV, the 4-pixel mixing mode is used. If the EV is less than 7 EV, the 8-pixel mixing mode is used. When the brightness of the subject is less than 11 EV, an aperture of F = 2.8 is used, and when it is 11 EV or more, an aperture of F = 8 is used.

Next, the two-pixel mixing mode, the four-pixel mixing mode, and the eight-pixel mixing mode will be described with reference to FIGS.

At the time of AF adjustment, eight lines L1 of the CCD 52 are used.
One line of image signal is read out every L8.
When the CCD 52 is driven in the two-pixel mixed mode, as shown in FIG.
Only the signal charges accumulated in the photosensors of the pixels L1 and L5 are transferred to the vertical transfer path 52A of the CCD 52.

The vertical transfer path 52A shifts signal charges on the vertical transfer path by 8 pixels in the vertical direction, and sequentially shifts the signal charges on the horizontal transfer path 5A.
Transfer to 2B. Therefore, in the horizontal transfer path 52B, the signal charges of the pixels on the lines L1 and L5 are mixed. After that, in the horizontal transfer path 52B, the signal charges on the horizontal transfer path are shifted in the horizontal direction, whereby
GR are read out as dot-sequential image signals. As described above, every time the signal charges are transferred by eight lines in the vertical direction by the vertical transfer path 52A, the charges on the horizontal transfer path 52B are shifted to read the image signal for one line.

Similarly, when the CCD 52 is driven in the four-pixel mixed mode, as shown in FIG.
8, only the signal charges accumulated in the photosensors of the pixels on lines L1, L3, L5, and L7 are transferred to the vertical transfer path 52A of the CCD 52.
Is driven, as shown in FIG.
The signal charges accumulated in the photo sensors of all the pixels of L8 are transferred to the vertical transfer path 52A of the CCD 52.

As is clear from FIGS. 6 and 7, in the two-pixel mixing mode and the four-pixel mixing mode, pixels of the same color are mixed.
And the signal charges of the R pixels are mixed, and the colors are mixed.

That is, in the case of an array in which the same horizontal lines are arranged every two pixels in the vertical direction like a color filter of a G stripe array, 2n (n: an integer of 2 or more, n = 4 in the embodiment) ) When reading one line of image signal for each line, a pixel mixing mode in which signal charges of n or less pixels are mixed to read one line of image signal (in the embodiment, a two-pixel mixing mode and a four-pixel mixing mode) mode)
In the pixel mixing mode, although the colors do not mix, the signal charges of more than n pixels are mixed and read out as an image signal of one line (8-pixel mixing mode in the embodiment).
Now, the colors will be mixed.

Therefore, the brightness of the subject is low (in the embodiment shown in FIG. 5, the brightness of the subject is less than 7 EV).
When the 8-pixel mixed mode is used as the operation mode of the CCD 52 at the time of the F adjustment, since the image signals acquired during the AF adjustment are mixed, a still image of a color in which the through image immediately before the start of the AF adjustment is stopped Is displayed on the liquid crystal monitor 30 or a luminance signal or a G signal is extracted from an image signal acquired during the AF adjustment, and a monochrome moving image is displayed on the liquid crystal monitor 30 based on the luminance signal or the G signal.

On the other hand, when there is a high-luminance subject, as shown in FIG.
Smear is mixed in 2A. In particular, when the subject is bright, smear increases. Here, eight lines L1 to L8
When the CCD 52 is driven in the two-pixel mixing mode in which the middle two lines L1 and L5 are mixed, pixel information is added by two pixels, while smear is added by eight pixels in the vertical direction. Will be more noticeable.

Therefore, as shown in FIG. 5, when the brightness of the object is 14 EV or more (the shutter speed is 9 TV).
(In the case of (time value) or more), a still image of a color in which the through image immediately before the start of the AF adjustment is stopped is displayed. This prevents a moving image in which smear is noticeable from being displayed on the liquid crystal monitor 30.

At the time of AF adjustment, if the brightness of the subject other than the above is not less than 7 EV and less than 14 EV in the embodiment shown in FIG.
A color moving image is displayed on the liquid crystal monitor 30 based on the image signal read from the CD 52.

FIG. 10 is a flowchart showing a method of displaying an image on the liquid crystal monitor 30 during AF adjustment.

As shown in the figure, first, the brightness of the subject is detected (step S10). The brightness of the subject can be obtained by calculating the average integrated value of the image signals of the entire screen. When the brightness of the subject is detected, the diaphragm is stopped according to the program diagram shown in FIG.
The shutter speed and the pixel mixing mode are determined (Step S12).

Subsequently, it is determined whether or not the determined shutter speed is equal to or greater than a predetermined value S (S = 9 TV in the embodiment shown in FIG. 5) in which smear is conspicuous (step S1).
4). If shutter speed ≧ S [TV], the image to be displayed on the liquid crystal monitor 30 is determined to be a still image immediately before the start of the AF adjustment (step S16).

On the other hand, if the shutter speed is smaller than S [TV], 2n (n: n: n when reading one line of image signal for every integer line of 2 or more) from the CCD during AF adjustment
Is detected (step S18). In this embodiment, n = 4 is fixed.

Subsequently, the number m of pixels to be mixed in the pixel mixing mode determined in step S12 (in this embodiment,
m = 2, 4, 8) and the above n (Step S2)
0) And, when 2n ≠ m (m = 2, 4), the CCD displayed as an image to be displayed on the liquid crystal monitor 30 during AF adjustment.
When a color moving image created based on the image signal acquired from the image 52 is determined (step S22), 2n = m (when m = 8), A is displayed as an image to be displayed on the liquid crystal monitor 30.
Color still image just before F adjustment start or CCD at AF adjustment
52 is determined to be a monochrome moving image created based on the image signal acquired from 52. (Step S24).

At the time of AF adjustment, the image determined as described above is displayed on the liquid crystal monitor 30, and AF adjustment is performed (step S26).

In this embodiment, the CCD provided with the color filters of the G stripe array has been described. However, the present invention is not limited to this. For example, the present invention can be applied to a Bayer array CCD. What is necessary is just to have a color filter in which the lines have the same color arrangement.

[0082]

As described above, according to the present invention, a moving image is displayed when the focus is automatically adjusted based on the image signal obtained from the image sensor. You can check the appearance and angle of view, and if the operation mode of the image sensor changes depending on the brightness of the subject, and as a result, color information is mixed and a good moving image cannot be displayed, Since a still image or monochrome moving image is switched, an appropriate image can be displayed at all times.

When the image signal acquired in the thinning mode at the time of the automatic focus adjustment contains many smear components (in the case of a bright subject having a high-luminance subject), a still image is displayed instead of a moving image. As a result, it is possible to prevent a moving image in which smear is noticeable from being displayed.

[Brief description of the drawings]

FIG. 1 is a front external view of an electronic camera according to the present invention.

FIG. 2 is a rear external view of the electronic camera shown in FIG. 1;

FIG. 3 is a block diagram showing the internal configuration of the electronic camera of the present embodiment.

FIG. 4 is a front view of a color filter having a G stripe arrangement.

FIG. 5 is an AF detection exposure program diagram.

FIG. 6 is a diagram used to explain a CCD read operation in a two-pixel mixed mode.

FIG. 7 is a diagram used to explain a CCD read operation in a four-pixel mixed mode.

FIG. 8 is a diagram used to explain a read operation of a CCD in an 8-pixel mixed mode.

FIG. 9 is a diagram used to explain the reason why the smear component is increased in the image signal taken in at the time of AF adjustment.

FIG. 10 is a flowchart illustrating a method of displaying an image on a liquid crystal monitor during automatic focus adjustment according to the present invention.

[Explanation of symbols]

Reference Signs List 10: electronic camera, 12: photographing lens, 30: liquid crystal monitor, 48: focus lens, 52: CCD (imaging means), 52A: vertical transfer path, 52B: horizontal transfer path, 54
... CCD driver, 62 ... Timing generator, 6
4 CPU, 78 focus drive unit, 88 evaluation value calculation unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 13/36 G03B 19/02 5C022 17/18 H04N 5/225 A 5C065 17/20 9/07 A 19 / 02 G02B 7/11 N H04N 5/225 D 9/07 G03B 3/00 A F term (reference) 2H011 AA03 BA33 BB02 BB04 DA01 DA05 2H048 BB02 BB06 BB46 2H051 AA00 BA47 CE01 DA22 EB01 EB20 GA03 GA13 2H054 AA01 A0301 AB11 BB08 CA01 5C022 AA13 AB28 AC03 AC13 AC18 AC32 AC42 AC54 AC69 AC80 5C065 AA03 BB24 CC02 CC03 CC08 CC09 DD02 DD17 EE05 EE06 FF03 GG18 GG30 GG32

Claims (13)

[Claims] An operation mode determining unit configured to determine one operation mode from the plurality of operation modes; and an operation mode determined by the operation mode determination unit. Image signal acquiring means for acquiring an image signal by driving an image sensor; automatic focus adjusting means for automatically performing focus adjustment based on the image signal acquired by the image signal acquiring means; and acquiring by the image signal acquiring means. Display means for displaying a moving image or a still image based on the obtained image signal, and switching means for switching an image to be displayed on the display means to a moving image or a still image according to the operation mode determined by the operation mode determining means. An electronic camera, comprising: A plurality of operation modes for driving the image sensor; an operation mode determination unit for determining one operation mode from the plurality of operation modes; and an operation mode determined by the operation mode determination unit. Image signal acquiring means for acquiring an image signal by driving an image sensor; automatic focus adjusting means for automatically performing focus adjustment based on the image signal acquired by the image signal acquiring means; and acquiring by the image signal acquiring means. Display means for displaying a color moving image or a monochrome moving image based on the image signal obtained, and switching means for switching an image displayed on the display means to a color moving image or a monochrome moving image according to the operation mode determined by the operation mode determining means. An electronic camera, comprising: 3. An operation mode determining means for detecting one of the plurality of operation modes in accordance with a brightness of the object detected by the detecting means. 3. The electronic camera according to claim 1, wherein the electronic camera is determined. 4. The image pickup device has a color filter in which horizontal lines have the same color arrangement every other line, and the plurality of operation modes are every 2n (n is an integer of 2 or more) lines from the image pickup device. A first pixel mixing mode in which information of n or less pixels in the vertical direction of the 2n lines are mixed to read out an image signal of one line; A second pixel mixing mode in which information of more than n pixels in the vertical direction is mixed and read out as an image signal of one line, wherein the operation mode determining means includes a brightness of the subject detected by the detecting means. Is darker, the pixel mixing mode in which the number of pixels to be mixed is larger is selected, and the switching unit switches the display unit when the first pixel mixing mode is determined by the operation mode determining unit. 4. The electronic camera according to claim 3, wherein an image to be displayed is switched to a moving image, and when the second mixed mode is determined, an image to be displayed on the display unit is switched to a still image. 5. The image pickup device has a color filter in which horizontal lines have the same color arrangement every other line, and the plurality of operation modes are 2n (n is an integer of 2 or more) lines from the image pickup device. A first pixel mixing mode in which information of n or less pixels in the vertical direction of the 2n lines are mixed to read out an image signal of one line; A second pixel mixing mode in which information of more than n pixels in the vertical direction is mixed and read out as an image signal of one line, wherein the operation mode determining means includes a brightness of the subject detected by the detecting means. Is darker, the pixel mixing mode in which the number of pixels to be mixed is larger is selected, and the switching unit switches the display unit when the first pixel mixing mode is determined by the operation mode determining unit. 4. The electronic camera according to claim 3, wherein an image to be displayed is switched to a color moving image, and when the second mixed mode is determined, an image to be displayed on the display unit is switched to a monochrome moving image. 6. An image signal acquiring means for driving an image sensor to acquire an image signal, an automatic focus adjusting means for automatically performing a focus adjustment based on the image signal acquired by the image signal acquiring means, and Display means for displaying a moving image or a still image based on the image signal acquired by the signal acquisition means; detection means for detecting the brightness of the subject; and display means according to the brightness of the subject detected by the detection means An electronic camera, comprising: switching means for switching an image to be displayed to a moving image or a still image. 7. An image displayed by the display means when the brightness of the subject detected by the detection means is equal to or higher than a predetermined brightness at which smear is noticeable in an image displayed on the display means. 7. The electronic camera according to claim 6, wherein the electronic camera is switched to a still image. 8. The electronic camera according to claim 7, wherein said image signal acquiring means reads out information of pixels in a vertical direction of said image pickup element at the time of focus adjustment by said automatic focus adjusting means. 9. A method for automatically adjusting focus based on an image signal obtained from an image sensor and displaying an image of a subject, the method for displaying an image of the subject during auto-focusing, comprising: detecting a brightness of the subject; Switching the operation mode of the image sensor at the time of automatic focus adjustment depending on whether the detected brightness of the subject is brighter than the first brightness, based on an image signal acquired from the image sensor at the time of automatic focus adjustment Automatically adjusting the focus, and when the detected brightness of the subject is brighter than the first brightness, a moving image based on the image signal acquired from the image sensor during the automatic focus adjustment. And when the detected brightness of the subject is lower than the first brightness, the image capturing is performed immediately before the automatic focus adjustment. The image display method for automatic focus adjustment, characterized in that it comprises a step of displaying a still image based on the image signal acquired from the child, the. 10. A method for automatically adjusting focus based on an image signal obtained from an image sensor and displaying an image of a subject in an image display method at the time of automatic focus adjustment, wherein a step of detecting a brightness of the subject; Switching the operation mode of the image sensor at the time of automatic focus adjustment depending on whether the detected brightness of the subject is brighter than the first brightness, based on an image signal acquired from the image sensor at the time of automatic focus adjustment Automatically adjusting the focus, and when the detected brightness of the subject is brighter than the first brightness, the color is adjusted based on the image signal acquired from the image sensor during the auto focus adjustment. Displaying a moving image; and when the detected brightness of the subject is lower than the first brightness, The image display method for automatic focus adjustment, characterized in that it comprises a step of displaying a monochrome video based on the image signal obtained from the imaging element. 11. The image sensor has a color filter in which horizontal lines have the same color arrangement every other line, and the operation mode of the image sensor is 2n (n
Is an integer of 2 or more). In this mode, one line of image signal is read out every line,
A first pixel mixing mode for reading information of one line by mixing information of not more than pixels, and mixing information of more than n pixels in the vertical direction of the 2n lines to form an image signal of one line A second pixel mixing mode for reading out, wherein the step of switching the operation mode includes the step of switching the first pixel mixing when the detected brightness of the subject is brighter than the first brightness during automatic focus adjustment. And switching to the second pixel mixing mode when the brightness is lower than the first brightness.
Or, an image display method at the time of automatic focus adjustment of 10. 12. A method for automatically adjusting focus based on an image signal obtained from an image sensor and displaying an image of a subject, the method for displaying an image of the subject during auto-focusing, comprising: detecting a brightness of the subject; Performing automatic focus adjustment based on an image signal obtained from the image sensor at the time of automatic focus adjustment; and if the detected brightness of the subject is equal to or higher than a second brightness, immediately before the automatic focus adjustment. Displaying a still image based on an image signal obtained from the image sensor, and wherein the detected brightness of the subject is lower than the second brightness from the image sensor during the automatic focus adjustment. Displaying a moving image based on the acquired image signal. An image display method at the time of automatic focus adjustment, comprising: 13. When the detected brightness of the subject is equal to or higher than the second brightness, the operation mode of the image sensor is a thinning mode in which pixel information in a vertical direction is thinned out and read out from the image sensor. The method according to claim 12, wherein the second brightness is a brightness in which smear is conspicuous when a moving image is displayed based on an image signal obtained from the image sensor during the automatic focus adjustment. Image display method at the time of focus adjustment.