JPH10319306A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optimum video not only in ordinary photographing but also in facing- state photographing by providing an auxiliary mechanism capable of performing control different from that in the case of the ordinary photographing when the facing-state photographing where the incident direction of a lens is aligned with the display direction of a monitor is performed. SOLUTION: Whether photographing is the ordinary photographing or the facing-state photographing is discriminated according to a detection signal from a photographing mode switching means. An automatic exposure(AE) evaluated value in the case of the ordinary photographing is detected by performing photometry on the brightness of a subject all over the image plane area, and the AE evaluated value in the case of the facing-state photographing is detected by performing the photometry only on the area of the central part of the image plane. By dividing the area where the photometry is performed into plural and weighting the AE evaluated value of every area, the AE evaluated value of the entire image plane is calculated. In the case of the facing-state photographing, the weighting of the AE evaluated value in the central part is made large so as to reduce the influence of the brightness of the subject in a peripheral part. Based on the detected AE evaluated value, a diaphragm mechanism, and an AGC means are controlled so as to perform exposure control. Thus, the expoure state of a main subject is kept optimum without exerting influenced by spotlight even when the subject of spotlight is photographed on the peripheral part.

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, it relates to face-to-face photography.

[0002]

2. Description of the Related Art The configuration and operation of a conventional imaging apparatus will be described below with reference to the block diagram of FIG.

[0003] In the configuration of the image pickup apparatus shown in FIG. 8, reference numeral 1 denotes a lens group for imaging an object, and a fixed first group lens 10.
1. Consisting of a variable power lens 102 for performing variable power, a fixed second lens unit 103, and a focus compensating lens (hereinafter referred to as a focus lens) 104 having both a function of correcting a movement of a focal plane due to variable power and a function of focusing. Reference numeral 3 denotes a zoom lens motor that drives the zoom lens 102 of the zoom lens 1 to adjust the zoom position, 4 denotes a zoom lens driving unit that drives the zoom lens motor 3, and 7 denotes a zoom lens.
Reference numeral 8 denotes a focus lens motor that drives the focus lens 104 of the zoom lens 1 to focus.
Is a focus lens driving means for driving the focus motor 7, a diaphragm mechanism means such as a diaphragm blade structure for controlling the amount of incident light, a diaphragm mechanism driving motor for driving the diaphragm mechanism means 2, and a diaphragm driving motor 6 A diaphragm mechanism driving means 5 for driving 5; an image pickup device 9 for photoelectrically converting incident light; and 10 an auto gain control (hereinafter, AGC) for sampling a signal photoelectrically converted by the image pickup device 9 and electrically amplifying the signal. CDS / AGC means for performing
11 is an analog-to-digital conversion (hereinafter referred to as A / D conversion) means for converting an analog signal output from the CDS / AGC means 10 into a digital signal.
A camera signal processing unit 13 for performing processing such as color separation and a color difference matrix to generate a standard television signal; and a digital-analog converter 13 for converting an output signal of the camera signal processing unit 12 from a digital signal state to an analog signal Means (hereinafter referred to as D / A conversion) means 14, monitor means for confirming the image of the subject being photographed by the photographer, 1
Reference numeral 5 denotes an AE evaluation value processing unit that obtains an evaluation value for performing exposure control from the video signal of the camera signal processing unit 12;
Reference numeral denotes AF evaluation value processing means for obtaining an evaluation value for performing focus control from the video signal of the camera signal processing means 12. Reference numeral 19 denotes an exposure control means for controlling exposure by controlling the AGC gain of the aperture mechanism 2 and the CDS / AGC means 10, and a focus for controlling the focus lens 104 to focus a subject to be imaged on an image sensor surface. It is a microcomputer that performs processing such as control means.

[0004] The image pickup apparatus having the above-described configuration is provided with an image pickup assisting mechanism that enables an optimum image to be obtained by an automatic or simple photographing operation. It should be noted that the term "automatic" used in the claims includes "semi-automatic" in which "the optimum image can be obtained by a simple photographing operation". An automatic exposure control unit (hereinafter, referred to as an AE control unit) that automatically optimizes an ever-changing brightness state of a subject being photographed, and an auto focus that automatically focuses on the subject as the photographing assist mechanism. There are control (automatic focus control) means (hereinafter referred to as AF control means), and these means will be described below.

Hereinafter, the AE control means will be described.

The AE control means detects the exposure state from the video signal of the subject, adjusts the amount of light incident on the image pickup element 9 by the aperture mechanism means 2 so as to optimize the exposure state, and controls the CDS /
A method is known in which the gain of a video signal is controlled by the AGC means 10 of the AGC means 10 so that the brightness is automatically corrected even if the brightness of the subject changes.

The AE control means having the configuration shown in FIG. 8 is controlled by the AE control means of the microcomputer 19 in accordance with the control flowchart shown in FIG.

Next, a description will be given with reference to a control flowchart of FIG.

First, in step 901, an AE evaluation value which is obtained by the AE evaluation value processing means 15 and which detects a change in brightness of a subject is detected from a video signal of the camera signal processing means 12. The AE evaluation value processing unit 15 detects the exposure state of the entire area of the video incident on the image sensor 9 so that the exposure state of the subject being photographed is optimized even in various photographing situations.

In step 902, a comparison is made between the current AE evaluation value detected in step 901 and a preset reference value for optimizing the preset exposure state to determine whether or not the exposure state is appropriate. An error amount from a reference value when the value is not appropriate is detected. If it is appropriate, the current exposure control value is output as it is, and if it is not appropriate, the AGC of the aperture mechanism means 2 or the CDS / AGC means 11 according to the error amount.
To calculate a control value such that the exposure state becomes the reference value. Here, a case where exposure control is performed according to the program diagram shown in FIG. 10 will be described as an example.

Photographing under sufficient illuminance such as outdoors (FIG. 10
In area B), in step 906, the AGC gain is fixed to the minimum gain (0 dB in FIG. 10), and when the brightness of the subject changes, a control value for compensating the error detected in step 902 by the aperture mechanism 2 is calculated. Then, the aperture state of the aperture mechanism 2 is opened and closed to adjust the amount of light incident on the image sensor 9, and the exposure state is optimally controlled. When the brightness of the object becomes dark and the aperture mechanism 2 is opened (area A in FIG. 10), and the exposure cannot be controlled by the aperture mechanism 2, the aperture mechanism is fixed to the open state in step 904, and the brightness of the object is increased. If the value has changed, a control value for compensating the error amount detected in step 902 with the AGC gain is calculated, and the exposure state is optimally controlled with the AGC gain.

The throttle mechanism means 2 obtained in this way,
Alternatively, each control value of the CDS / AGC means 10 is
07, and by updating the control value, control is performed so as to always follow the brightness of the subject to obtain an optimal exposure state.

Next, the AF control means will be described.

As the AF control means, there is known a method of detecting sharpness of a subject image from a video signal, controlling a focus lens position so as to maximize the sharpness, and adjusting a focus. In general, the sharpness is evaluated based on the intensity of a high-frequency component of a video signal extracted by a band-pass filter or the blur width detection intensity of a video signal extracted by a differentiating circuit or the like. Normally, when the subject is photographed as shown in FIG. 11, these signals are small when the subject is out of focus, and are large as the subject is in focus.
It reaches the maximum value when it is completely in focus. Accordingly, when the sharpness signal is small, the focus lens is controlled so as to move as fast as possible in the direction in which the sharpness signal increases, and as the sharpness signal increases, move slowly so that the focus lens is stopped accurately at the top of the mountain, that is, the focus is adjusted. Such an autofocus method is generally called hill-climbing autofocus (hereinafter, hill-climbing AF).

The hill-climbing AF control means having the configuration shown in FIG. 8 will be described with reference to FIGS. 12 to 15 which are control flowcharts of the AF control means of the microcomputer 19.

First, an AF evaluation value is fetched from the AF evaluation value processing means 16 in step 1201 of FIG. Step 1
At 202, the current AF mode is determined.

In the restart determination processing, step 13 in FIG.
01 and the held value and AF held when shifting to the restart determination mode
The evaluation values are compared, and if the difference between the held value and the AF evaluation value is larger than the predetermined value in step 1302, the process proceeds to the direction determination process, and if not larger, the process ends.

In the direction determination process, step 140 in FIG.
In step 1, wobbling for vibrating the focus lens 104 back and forth is performed, and it is determined whether the focus lens 104 is in focus or out of focus. If out of focus, step 1406
To return to the processing in the hill-climbing processing mode, and if in-focus, the flow returns to the processing in the restart determination mode in step 1404.

In the hill climbing process, first, step 1 in FIG.
At 501, a peak hold of the AF evaluation value is performed. This is A
If the F evaluation value is larger than the current peak value, the value is newly set as the peak value. If the F evaluation value is larger than the focus lens position, the value is set as the new peak value, and the focus lens position is held. . Next, in step 1502, it is determined whether or not the AF evaluation value is larger than the initial value of the hill-climbing held in step 1407 of FIG. If it is larger, it is determined in step 1503 whether the AF evaluation value is smaller than the peak value. If the AF evaluation value is not smaller than the peak value, the process ends. If the AF evaluation value is smaller than the peak value, a process of returning to the focus lens position of the peak value is performed in step 1504, and it is determined in step 1505 whether or not the focus lens position of the peak value has been returned. Move on to processing. If not, the process ends. If the AF evaluation value is smaller than the hill-climbing initial value in step 1502, the hill-climbing direction is reversed in step 1507 to drive the focus lens in the opposite direction.
At step 8, the initial value of the hill climbing is updated to the current AF evaluation value.

As described above, the focus lens is controlled so as to maximize the AF evaluation value while repeating the restart determination process → direction determination process → hill climbing process → restart determination process, so that the subject is always in focus. An image that matches is obtained.

In an image pickup apparatus such as a video camera provided with a photographing auxiliary mechanism such as an AE control means and an AF control means, a small CRT or a liquid crystal display is used as a monitor means for confirming a picture taken by a photographer. An electronic viewfinder (hereinafter referred to as EVF) for enlarging an image on a panel by an optical enlarging means such as an enlarging lens has been conventionally used.
With the structure in which the display surface of the EVF is arranged in the direction opposite to the lens as in (a), a style in which the photographer shoots while viewing the image projected on the EVF is general.

In recent years, as shown in FIG. 16 (b), a monitor means (hereinafter referred to as a large monitor means) which allows a photographer to directly look at an image without using an optical magnification means using a large liquid crystal panel or the like. 16), and an imaging device having both an EVF and a large monitor as shown in FIG. 16C.

In an image pickup apparatus having such a large monitor means, the display screen of the large monitor means is arranged in the direction opposite to the incident direction of the subject light incident on the image pickup lens as shown in FIG. The large monitor means is different from the EVF in that the photographer can confirm the image on the monitor means even if the photographer takes his / her eyes to some extent, unlike the EVF. A structure in which the display screen of the large monitor means is arranged in the same direction as the incident direction of the subject light entering the camera, and the photographer himself is photographed while watching the image of the large monitor means as shown in FIG. Has been proposed.

In this face-to-face shooting, AE and AF control following the subject is performed by the same AE control means and AF control means as in normal shooting, so that an optimum image can be obtained.

[0025]

However, the control of the photographing auxiliary mechanisms such as the AE control means and the AF control means mainly performs control assuming a photographing situation during normal photographing. Appropriate control is not always performed because it differs from shooting.

For example, in the AE control means at the time of normal photographing, not only a scene having a uniform brightness on the entire screen but also a backlight scene or a scene with spotlight illumination, etc. Although it is optimized to some extent, it performs fast-response control for changes in the brightness of the subject.However, in face-to-face shooting, the photographer himself is photographed while viewing the image on the large monitor means. The change is small, and if the same AE control is performed as in normal shooting, there is a problem that the brightness of the main subject changes in response to the change in brightness of the surrounding subject.

Also, the AF control means performs control so that the distance to the subject during normal shooting is in focus from close-up shooting within 1 meter to shooting near infinity such as landscape, but the AF measurement for detecting the AF evaluation value is performed. When a distant subject exists in the distance area, the main subject is focused when the main subject is predominantly photographed at the center of the screen as shown in FIG. 7A. If the main subject is accidentally focused from the center of the screen due to camera shake or temporary movement of the subject during shooting, if the focus is mistakenly focused on the background, the shooting distance is about 1 meter in face-to-face shooting, The main subject becomes largely blurred as compared with the time of normal shooting, and the problem becomes conspicuous.

In the face-to-face shooting of the imaging apparatus provided with the large monitor means, the control of the shooting assist mechanisms such as the AE and the AF corresponding to a wide range of shooting conditions as in the case of the normal shooting can be performed. Often, the video does not look good.

The present invention has been made under such circumstances, and it is an object of the present invention to provide an imaging apparatus capable of obtaining an optimum image not only in normal shooting but also in face-to-face shooting. is there.

[0030]

In order to achieve the above-mentioned object, according to the present invention, an imaging device is configured as described in the following (1) to (5).

(1) A subject image forming lens, a monitor capable of changing a display direction relative to an incident direction of subject light incident on the lens, and a photographing assist mechanism for automatically adjusting photographing conditions. Wherein the imaging assistance mechanism is capable of performing control different from that during normal imaging when face-to-face shooting in which the incident direction of the lens and the display direction of the monitor match. An imaging device.

(2) The photographing assistance mechanism has automatic exposure control means, and the automatic exposure control means performs control different from that in normal photographing in a face-to-face photographing mode than in normal photographing. Imaging device.

(3) The image pickup apparatus according to the above (2), wherein the automatic exposure control means makes the response slower in face-to-face shooting than in normal shooting.

(4) An imaging apparatus in which the photographing assistance mechanism has an automatic focus control means, and the automatic focus control means performs control in a sequence different from that in normal photographing at face-to-face photographing.

(5) The image pickup apparatus according to the above (5), wherein the automatic focus control means makes the response slower in face-to-face shooting than in normal shooting.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples of an image pickup apparatus.

Although the embodiment has a large monitor, it is not necessary to check the focus state on the monitor in the case of auto focus or in the case of using a fixed focus imaging lens. In this case, since it is sufficient to confirm the position of the subject, the embodiment can be implemented with a small monitor. Further, although the embodiment is an apparatus for photographing a moving image, the present invention is not limited to this, and may be implemented in an apparatus for photographing a still image.

[0038]

【Example】

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of an "imaging device" according to Embodiment 1. The portions denoted by the same reference numerals as the conventional example shown in FIG. 8 have the same functions as the conventional example,
The process of processing a video signal is the same, and in this embodiment,
The control at the time of face-to-face shooting is added to the shooting mode switching means 18 such as a switch means for switching between normal shooting and face-to-face shooting, and the AE control means of the microcomputer 17. As the structure of the device, as shown in FIG. 18, it is assumed that the lens unit is movable with respect to the main body to which the monitor is fixed. However, the present invention is not limited to this. Shapes can be similarly implemented.

In general, face-to-face shooting is performed at a distance at which the photographer can confirm the image shown on the large LCD monitor.
The photographer can hold it by hand or place it in an appropriate location
The shooting takes place ~ 2 meters away. For this reason, the shooting conditions are more limited than in normal shooting. In the AE control means of the present embodiment, AE control is performed in accordance with the above-described face-to-face shooting conditions separately from normal shooting.

Next, the operation of the AE control means of this embodiment will be described with reference to the control flowchart of FIG.

First, in step 201, a photographing mode of normal photographing or face-to-face photographing is determined from the detection signal of the photographing mode switching means 18, and in the case of normal photographing, the AE evaluation value is detected in step 202. In the case of face-to-face photographing, step 203 is performed. AE evaluation value detection processing is performed. AE of steps 202 and 203
In the evaluation value detection, a change in the brightness of the subject is detected from the video signal of the camera signal processing means 12. At this time, the AE evaluation value detection during normal shooting in step 202 generally measures the brightness of the subject in the entire screen area as shown in FIG. 3A, but the AE evaluation value during face-to-face shooting in step 203 Since the detection is mainly performed when the photographer's face is photographed near the center of the screen, only the area at the center of the screen is measured as shown in FIG. 3B to detect the AE evaluation value. Also, in the case where the photometric area is divided into a plurality of parts and the AE evaluation value of each area is weighted to calculate the AE evaluation value of the entire screen, the weighting of each area at the time of face-to-face photographing is performed as shown in FIG. As shown in FIG. 4B, the weight of the AE evaluation value of the area in the central portion is larger than that in the normal photographing of FIG. The AE evaluation value is detected as follows.

Based on the AE evaluation value thus detected, the process proceeds to step 204 in the same manner as in the prior art, and the exposure control is performed by controlling the aperture mechanism and the AGC means in accordance with the program diagram of FIG.

As described above, in face-to-face photography, AE control is performed by focusing light more on the central portion of the screen than in normal photography, so that even if a subject with a spotlight is photographed in the periphery, it is not affected. The exposure state of the main subject is kept optimal.

In addition to changing the photometry of the AE, FIG.
In steps 206 and 208, control may be performed such that the AE control response is made slower than during normal shooting by changing the control amount of the aperture mechanism and the AGC gain for the change in brightness of the subject. With this, in the face-to-face shooting, even when the main subject deviates from the center of the screen due to camera shake or temporary movement of the subject during shooting, an image in which the exposure state of the main subject is stable without suddenly changing the exposure state can be obtained. .

(Embodiment 2) In this embodiment, AF in face-to-face photography
This is an example in which the control is changed from that of the first embodiment.

The hardware configuration is the same as that of the first embodiment. In this embodiment, the control at the time of face-to-face shooting is added to the AF control means of the microcomputer 17.

As described in the first embodiment, in the face-to-face shooting, the shooting conditions are more limited than in the normal shooting. In particular, the shooting distance between the imaging device and the subject is wide from several centimeters to an infinite distance in the normal shooting. In contrast, face-to-face photography is limited to around 1 meter. In this embodiment, the AF control means performs AF control in accordance with the above-described face-to-face shooting conditions separately from normal shooting.

The operation of the AF control means will be described.

First, as in the conventional case, step 120 in FIG.
In step 1, the AF evaluation value is fetched from the AF evaluation value processing means 16. In step 1202, the current AF mode is determined,
In the case of the restart mode and the direction determination mode, the same processing as that of the related art is performed, and in the case of the hill-climbing mode, the processing is performed according to the control flowchart of FIG.

Next, the hill-climbing operation of the AF control means in this embodiment will be described with reference to the control flowchart of FIG.

First, in step 501, a photographing mode of normal photographing or face-to-face photographing is determined. If the photographing mode is the normal photographing mode, the process proceeds to step 503, and the same processing as the conventional one (see FIG. 15) is performed. In the case of the face-to-face shooting mode, the process proceeds to step 502, where the current focus lens position is detected, and it is determined whether the current focus lens position is within or outside a preset lens control range. This lens control range is, for example, the entire controllable range from close to infinity as shown in FIG. 11 during normal shooting as shown in FIG. 11, whereas the distance to the subject is limited during face-to-face shooting. As shown in the above, the setting is limited to a range around 1 meter. Here, if the current focus lens position is within the lens control range of FIG. 6, the process proceeds to step 503, and the hill-climbing control similar to the conventional one is continued. However, if the current focus lens position is beyond the lens control range, the process of the hill-climbing control is terminated and the mode shifts to the direction determination mode even if the AF evaluation value is smaller than the peak value.

As a result, during face-to-face shooting, the focus is adjusted only at the focus lens position in the lens control range in FIG. 6, so that the main subject is moved from the center of the screen due to camera shake or temporary movement of the subject as shown in FIG. Even when trying to focus on an object in the background that deviates, there is no control to the focus position where the focus lens position becomes large as shown in FIG. Therefore, the main subject will not be largely blurred, and the focus control will be quick because the lens control range is narrow.

Also in this embodiment, a more stable image can be obtained by delaying the response of the AF control.

In each of the above embodiments, the photographing mode switching means is externally provided. However, the present invention is not limited to this. When the imaging lens comes to the face-to-face photographing position, the apparatus switches from normal photographing to face-to-face photographing. The mode may be switched. Further, in the first aspect, a state in which the incident direction of the lens and the display direction of the monitor coincide with each other is defined as “face-to-face shooting”.
Since the monitor can be viewed from an oblique direction, the term "matching" is used to include not only perfect matching but also "substantially matching" which is a range in which face-to-face shooting is possible.

[0055]

As described above, according to the present invention,
Optimal images can be obtained not only in normal shooting but also in face-to-face shooting.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment.

FIG. 2 is a flowchart of AE control according to the first embodiment.

FIG. 3 is a diagram showing an example of photometry for detecting an AE evaluation value.

FIG. 4 is a diagram showing an example of photometry for detecting an AE evaluation value when a screen is divided.

FIG. 5 is a control flowchart of a hill-climbing process according to the second embodiment.

FIG. 6 is an explanatory diagram of face-to-face photographing.

FIG. 7 is an explanatory diagram of face-to-face photographing.

FIG. 8 is a block diagram showing a configuration of a conventional example.

FIG. 9 is a flowchart of AE control in a conventional example.

FIG. 10 is a program diagram of AE control in a conventional example.

FIG. 11 is an explanatory diagram of AF control in a conventional example.

FIG. 12 is a flowchart of AF control in a conventional example.

FIG. 13 is a control flowchart of an AF restart process in a conventional example.

FIG. 14 is a control flowchart of a direction determination process in a conventional example.

FIG. 15 is a control flowchart of a hill-climbing process in a conventional example.

FIG. 16 is an explanatory view of an EVF and a large monitor.

FIG. 17 is an explanatory diagram of face-to-face shooting;

FIG. 18 is an explanatory diagram of face-to-face photographing.

[Explanation of symbols]

 1 zoom lens for subject imaging 14 monitoring means 17 microcomputer

Claims (5)

[Claims] 1. A lens for imaging a subject, a monitor capable of changing a display direction relative to an incident direction of the subject light incident on the lens, and a shooting assistance mechanism for automatically adjusting shooting conditions. Wherein the imaging assistance mechanism is capable of performing a different control from the other ordinary imaging at the time of face-to-face shooting in which the incident direction of the lens matches the display direction of the monitor. An imaging device characterized by the above-mentioned. 2. The photographing assisting mechanism has automatic exposure control means, and the automatic exposure control means performs control different from that in normal photographing at the time of face-to-face photographing. Item 2. The imaging device according to Item 1. 3. The automatic exposure control means includes:
3. The image pickup apparatus according to claim 2, wherein a response is made slower than during normal photographing. 4. An image pickup apparatus according to claim 1, wherein said photographing assisting mechanism has an automatic focus control means, and said automatic focus control means performs control in a sequence different from that in a normal photographing at face-to-face photographing. apparatus. 5. The automatic focus control means includes:
5. The image pickup apparatus according to claim 4, wherein a response is made slower than during normal photographing.