JPH0998333A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain stable focus to an objective major object under any image and pickup condition even when any lens is mounted by supplying information relating to the image pickup state to a lens microcomputer at a lens unit side from a camera main body. SOLUTION: A lens unit 127 is attached/detached to/from a camera main body 128. Then the lens unit 127 is provided with image pickup lenses having stationary lens groups 101, 104, a magnification lens group 102 and a focus lens 105 and with a lens microcomputer 120 controlling the lens groups 102, 104. An image pickup means consisting of image pickup elements 106-108 and a camera signal processing circuit 112 is used to convert the image formed by the image pickup lens into an image pickup signal and it is outputted. A main body microcomputer 114 sends information relating to the image pickup state of the image pickup means to the lens unit 127. Thus, even when a control means such as focus adjustment device is provided in the lens unit, the image pickup state is accurately recognized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus suitable for use in a video camera or the like with interchangeable lenses.

[0002]

2. Description of the Related Art Conventionally, a CCD has been used as an automatic focusing (AF) device used in a video device such as a video camera.
A so-called hill-climbing method is known in which a high-frequency component in a video signal obtained from an image pickup device is extracted, and a photographing lens is driven to adjust the focus so that the high-frequency component is maximized.

Such an automatic focus adjustment method has an advantage that a special optical member for focus adjustment is not required, and the focus can be accurately adjusted regardless of the distance even at a long distance. An example in which this type of automatic focus adjustment method is used in a video camera in which the lens can be exchanged will be described with reference to FIG.

In a conventional variable-magnification lens unit, a variable-magnification lens 902 and a correction lens 903 are mechanically connected by a cam. When the variable-magnification operation is performed manually or electrically, the variable-magnification lens 9 is used.
02 and the correction lens 903 move integrally. The variable magnification lens 902 and the correction lens 903 are collectively referred to as a zoom lens.

In such a lens system, the front lens 901 is a focus lens, and the focus is adjusted by moving in the optical axis direction.

The light passing through these lens groups is imaged on the image pickup surface of the image pickup device 904, photoelectrically converted into an electric signal, and outputted as a video signal.

This video signal is sampled and held by the CDS / AGC 905 and then amplified to a predetermined level.
Converted to digital video data by the / D converter 906,
It is supplied to the process circuit of the camera and converted into a standard television signal.

On the other hand, the digital video data output from the A / D converter 906 is a bandpass filter (hereinafter BP).
(Referred to as F) 907.

The BPF 907 extracts the high frequency component of the video signal, the gate circuit 908 extracts only the signal corresponding to the part set in the focus detection area in the screen, and the peak hold circuit 909 multiples the vertical synchronizing signal. Peak hold is performed at an interval synchronized with, and an AF evaluation value is generated.

This AF evaluation value is calculated by the main body AF microcomputer 910.
In the main body AF microcomputer 910, the motor driving direction is determined so that the focus speed according to the focus degree and the AF evaluation value increase, and the speed and direction of the focus motor are sent to the lens microcomputer 911.

The lens microcomputer 911 is an AF microcomputer 9
Focusing is performed by moving the focusing lens 901 in the optical axis direction by the motor 913 via the motor driver 912 as instructed by 10.

Further, according to the operation state of the zoom switch 918, the AF microcomputer 910 causes the zoom lenses 902, 9
03 drive direction and drive speed are determined, and the lens unit 9
The zoom lens 902 and 903 are sent to the zoom motor driver 914 in 16 through the zoom motor 915.

The camera body 917 is a lens unit 91.
6 can be separated, and the shooting range is expanded by connecting another lens unit.

However, in the image pickup apparatus as shown in FIG. 10, since the lens can be exchanged, the main body has the control of the automatic focus adjustment. Therefore, the responsiveness of the automatic focus adjustment is determined so as to be optimum for a specific lens. Then, it may not be optimal for other lenses, and it was difficult to achieve optimal performance for all removable lenses.

Therefore, an image pickup apparatus has been proposed in which the lens unit has control of automatic focus adjustment, and the focus signal necessary for executing the focus adjustment is passed from the image pickup apparatus main body to the lens unit.

In this case, in order to determine the optimum autofocus responsiveness for all the connected lenses,
The focus obtained from the main body is determined by the lens unit side that has the means for determining the size of the extraction area that extracts the focus signal from the video signal, and passes the size information to the main body side, setting the appropriate size according to the focal length of each lens. The signal level is optimized.

This is because if the extraction area is fixed to the screen size regardless of the type of lens, for example, in a wide-angle lens, various subjects are present in the area and the focus signal level tends to be high, so that The signal is saturated for a brightness subject, making it difficult to perform appropriate focus adjustment, while the telephoto lens enlarges the subject image, and the focus signal level tends to be low, which makes AF difficult for low-illuminance subjects. It is based on reasons such as being lost.

[0018]

However, in the image pickup apparatus in which the lens is exchangeable, which has the automatic focus adjustment control in the lens unit as in the above-mentioned conventional example, the image pickup state of the main body side is adjusted by the automatic focus adjustment means in the lens unit. Cannot be recognized, so there were the following problems.

When photographing is performed using a lighting device such as a household fluorescent lamp that uses discharge as a light source, so-called flicker occurs, in which discharge occurs and stops repeatedly depending on the frequency of the AC power source of the light source, and the output level of the image pickup signal is generated. However, since there is no flicker on the lens unit side, it is unknown whether the change in AF evaluation value is due to the movement of the focusing lens or the influence of flicker during focus adjustment. Instead, the focus direction may be wrong.

Further, if the lens driving and the fetch timing of the AF evaluation value are always synchronized with the flicker cycle in order to remove the influence of flicker, there arises a problem that the AF responsiveness becomes slow.

When shooting a low-illuminance subject, etc.
Although the image pickup signal is amplified by the GC, noise is also amplified together, and the AF evaluation value has a large noise component.
Since the amount of amplification is not known on the lens unit side, it often causes a malfunction due to the influence of noise when the focus adjustment operation is restarted or when the hill climbing direction is determined, which causes blurring.

In the case of shooting using a so-called program mode, which automatically realizes an optimum shooting state by automatically adjusting the aperture, shutter, AGC, etc. so that effective shooting can be performed according to the selected shooting conditions, Although the exposure state changes due to the mode change, the mode change cannot be seen on the lens unit side.

When the program mode changes, the AF evaluation value also changes, which causes a malfunction of the AF.
Especially when the mode changes in the in-focus state and the aperture can be compulsorily opened for the purpose of shooting effects, the depth of field becomes shallow, but when the angle of view is wide and when shooting high-brightness subjects, it may be overexposed. Therefore, the image pickup signal level may exceed the dynamic range of the image pickup device.
The F evaluation value does not change before and after the mode change. Therefore, as the depth became shallower, blurring was seen and the phenomenon of blurring had stopped.

Since the lens unit itself drives the diaphragm in response to a control command from the image pickup apparatus main body, the diaphragm state can be recognized, but whether it is for optimizing the exposure or the photographing effect. I can't judge whether it is what I was aiming for.

If the aperture is changed to compensate for the above-mentioned drawbacks,
The focus adjustment may be restarted, but if the restart operation is performed each time the aperture is changed, the AF will be stable.

In the case of shooting using a so-called slow shutter, in which the accumulation time of the image pickup element is set to be an integral multiple of the normal length and the image pickup signal is read out intermittently, the focus signal sent from the main body side is the focus for the time of the reading cycle. Although the signal will not be updated, the reading cycle is not known on the lens unit side, and the focus signal does not change for a certain period of time, so it was erroneously determined to be in focus and the hill climbing direction was incorrect.

In the case of photographing using a magnifying function such as electronic zoom, since the lens unit side does not know where in the image pickup screen and how many times it is magnified, the focus signal extraction region may be larger than the magnified region. In some cases, the subject that has not been moved to the monitor may be focused at this time.

Further, by enlarging the screen, even a blur within the depth of field becomes visible, so that
Blurring caused by a minute driving operation such as wobbling performed in the focusing method determination operation was visible.

An object of the present invention is to solve the above-mentioned problems and provide an interchangeable lens system capable of stably focusing on a target main subject regardless of the type of lens attached and under all subjects and shooting conditions. To do.

[0030]

In order to solve the above problems, according to the invention of claim 1 in the present application, a lens unit including an imaging lens and a control means for controlling the imaging lens can be attached and detached. Image pickup device that converts an image formed by the image pickup lens into an image pickup signal and outputs the image pickup signal (in the embodiment, the image pickup elements 106 to 108,
(Corresponding to the camera signal processing circuit 112) and control means (corresponding to the main body microcomputer 114 in the embodiment) for transmitting information regarding the image pickup state of the image pickup means to the lens unit.

According to the second aspect of the present invention, the image pickup means for photoelectrically converting the incident light and outputting the image pickup signal (corresponding to the image pickup elements 106 to 108 and the camera signal processing circuit 112 in the embodiment). A lens unit that is attachable to and detachable from an image pickup apparatus main body, including: an image pickup lens; a control unit that controls the image pickup lens (corresponding to the lens microcomputer 116 in the embodiment); The lens unit is provided with a unit (corresponding to the lens microcomputer 116 in the embodiment) that takes in information regarding the image pickup state of the image pickup unit and changes the operation of the control unit.

According to the invention of claim 3 of the present application, in claim 1 or 2, the information relating to the imaging state is color temperature information in the imaging screen.

According to the invention of claim 4 in the present application, in claim 1 or 2, the information on the image pickup state is exposure information.

According to a fifth aspect of the present invention, in the fourth aspect, the image pickup means includes an image pickup element and a storage time control means for controlling a storage time of the image pickup element, and the exposure information is The information is related to the storage time of the image sensor.

According to a sixth aspect of the present invention, in the fourth aspect, the image pickup means includes an amplifier having a variable amplification factor for controlling the level of the image pickup signal,
The exposure information is amplification factor information of the amplifier.

According to the invention of claim 7 in the present application, in claim 4, the image pickup means includes a diaphragm mechanism for controlling an incident light amount, and the exposure information is used as diaphragm information of the diaphragm mechanism. .

According to an eighth aspect of the present invention, in the fourth aspect, the image pickup means is a photographing mode setting means capable of setting a plurality of photographing modes which can be arbitrarily selected according to photographing conditions. Further, the exposure information is program mode information for controlling the exposure state of the image pickup means, the camera signal processing state such as gamma correction, and aperture correction for each of the photographing modes.

According to a ninth aspect of the present invention, in the fifth aspect, the exposure information is read out from the image sensor by increasing the accumulation time of the image sensor to an integral multiple of the normal time. Is used as the read cycle information of the slow shutter which is intermittently performed.

According to a tenth aspect of the present invention, in the first or second aspect, the image pickup apparatus main body includes image magnification changing means for electronically enlarging or reducing a part of the image pickup screen, The information regarding the image pickup state is the image magnification information of the subject in the image magnification changing means.

According to an eleventh aspect of the present invention, in the first or second aspect of the present invention, the image pickup state information includes the intensity of light emission, lighting / flashing depending on the frequency of the power source of the illumination means for illuminating the subject. Information about the cycle was used.

According to a twelfth aspect of the present invention, in the first or second aspect, a focus control means for changing the control method for adjusting the focus of the image pickup lens according to the image pickup state information is provided. It has a different configuration.

According to a thirteenth aspect of the present invention, in the second aspect, the distance measurement frame size control means for setting the size of the distance measurement frame within the image pickup screen and the distance measurement frame size control means are used. The distance measuring frame size information thus set is provided to the image pickup apparatus main body.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. The lens unit 127 and the camera body 128 can be separated from each other, which constitutes a so-called interchangeable lens system.

The light from the subject is a fixed first lens group 101, a second lens group (hereinafter referred to as a variable magnification lens) 102 for changing the magnification, a diaphragm 103, and a fixed third lens. The red component of the three primary colors is imaged through the group 104, a fourth lens group (hereinafter referred to as a focus lens) 105 that has a focus adjustment function and a compensator function that corrects the movement of the focal plane due to zooming. Image pickup device 106 such as a CCD, an image pickup device 107 such as a CCD for picking up a green component, and an image pickup device 108 such as a CCD for picking up a blue component are imaged and photoelectrically converted on the image pickup surfaces. Then, an image pickup signal corresponding to each color component of the red component, the green component, and the blue component is output.

The image pickup signals of the respective color components outputted from the respective image pickup devices are respectively amplified to optimum levels by amplifiers 109, 110 and 111, inputted to the camera signal processing circuit 112 and converted into standard television signals at the same time. , AWB (Auto white b) provided in the camera signal processing circuit 112
alance) signal processing circuit 130, AE (Auto exposure)
The signal is input to the signal processing circuit 131, the AF (Auto focus) signal processing circuit 113, and the flicker detection circuit 115.

The color difference signal SAWB generated by the AWB signal processing circuit 130 is arranged in the camera body and is supplied to the AWB / exposure control unit 135 in the body microcomputer 114 which controls the system as a whole, and the color difference signal SAWB is supplied. The amplifiers 109, 110 and 111 are controlled so as to be zero and white balance control is performed, while the control information is sent to the lens microcomputer 116 as color temperature information.

The photometric signal SAE generated by the AE signal processing circuit 131 is sent to the AWB / exposure control unit 135 and is used for exposure control, while the photometric area control is performed by predominantly measuring only a partial area within the screen. Is the AE signal processing circuit 13
Sent to 1.

The AWB / exposure controller 135 also controls the exposure, and drives the CCD drive circuit 136 so that the exposure state of the photometric signal becomes a desired state, and the image sensor 106,
Accumulation time of 107 and 108, amplifiers 109 and 110,
The lens microcomputer 11 sends the gain of 111 and the aperture drive command.
The amount of light transmitted to the aperture control unit 120 of No. 6 and passing through the aperture 103 is feedback-loop controlled.

The diaphragm 103 is controlled by the diaphragm controller 120 sending a signal to the iris driver 124 in response to a diaphragm driving command sent from the camera body.
Is performed, the driven diaphragm state is detected by the encoder 129, and the encoder output signal is transferred to the AWB / exposure control unit 135 in the main body microcomputer 114 through the diaphragm control 120.

The AWB / exposure control unit 135 also controls the program mode with emphasis on the exposure control.
Parameters such as an aperture mechanism, an amplifier such as an AGC, and an electronic shutter are controlled according to the mode selected by the photographer by operating the program mode switching SW unit 138 to realize an optimal exposure state for the subject and the photographing situation.

Further, the AWB / exposure control unit 135 also controls a slow shutter function for photographing a low illuminance subject. In accordance with the slow shutter speed selected by the slow shutter SW unit 139, the CCD drive circuit 136 is controlled to change the charge accumulation time of the image pickup devices 106, 107, 108 to be longer than usual, and the read cycle is adjusted to that to intermittently pick up images. The signal is taken out (the storage period changes with the electronic shutter, but the read cycle is constant).

The read intermittent image pickup signal is taken into the field memory 132 through the camera signal processing unit 112, and the AWB / exposure control unit 135 controls the memory control / interpolation circuit 133 to store the stored image information in the camera. By passing the signal to the signal processing unit 112, the video information of the missing field during the read cycle is supplemented.

The AWB / exposure control unit 135 performs the above-described exposure control, program mode control, and slow shutter control, while electronic shutter information as exposure information, amplification factor information such as AGC, aperture control information, and a selected program. The mode information and the read cycle information at the time of slow shutter are sent to the lens microcomputer 116 in the lens unit.

AF generated by the AF signal processing circuit 113
The evaluation value is transferred to the lens microcomputer 116 via the main body microcomputer 114, while the information on the distance measuring area in the screen determined by the distance measuring frame size control unit 142 in the lens microcomputer 116 is transmitted to the main body microcomputer 114. Then, it is sent to the AF signal processing circuit 113 via the main body microcomputer 114.

The distance measuring frame size control unit 142 determines the distance measuring area of the optimum size for extracting the AF performance according to the focal length of the lens unit 127 to be mounted. The size of the distance measuring frame is determined in the lens unit for the reason described in the above-mentioned conventional example.

Further, the main body microcomputer 114 is a zoom switch unit 137 (a unit that outputs a voltage corresponding to a resistance value that changes according to a change in the rotary operation member,
By A / D converting the output voltage, the rotation direction and the rotation amount of the operating member can be obtained as a digital signal), and A
The F switch 141 is read and the state of the switch is sent to the lens microcomputer 116.

In the lens microcomputer 116, when the AF switch 141 is off (manual focus mode) and the zoom switch unit 137 is pressed according to the information from the main body microcomputer 114, the AF / computer zoom control program 117 causes the lens Cam data 119
Referring to, the control unit sends a control signal to the zoom motor driver 122 to drive in the tele or wide pressed direction, thereby driving the variable power lens 102 via the zoom motor 121 to perform a variable power operation. . At the same time, by sending a control signal to the focus motor driver 126, the focus lens 125 is driven via the focus motor 125, and the shift of the focus position due to the zooming operation is corrected.

When the AF switch 141 is on and the zoom SW unit 137 is pressed, it is necessary to keep the in-focus state for both the zooming operation and the change of the object distance. A zoom control program 117 is sent from the main unit microcomputer 114.
With reference to the F evaluation value signal, the scaling operation is performed while maintaining the position where the AF evaluation value is maximum.

When the AF switch 141 is on and the zoom switch 137 is not pressed, the AF / computer program 117 causes the focus motor driver 126 to maximize the AF evaluation value signal sent from the main body microcomputer 114. Signal to the focus motor 1
By moving the focus lens 105 via 25, an automatic focus adjustment operation is performed.

The flicker signal S generated by the flicker detection circuit 115 in the camera signal processing unit 112 in the camera body.
The FL is sent to the main body microcomputer 114 to determine the presence or absence of flicker, and the lens microcomputer 11 is used as flicker presence / absence information.
Sent to 6.

The flicker signal SFL will be described with reference to FIG. FIG. 5 shows the flicker and the change in the output of the image sensor when the frequency of the AC power source is 50 Hz and the standard of the output signal of the video camera is NTSC system, that is, when the vertical synchronizing frequency is 60 Hz.

FIG. 5A shows a change of the absolute voltage of the AC power supply with respect to time. Since the AC power supply waveform is a sine wave, the waveform of the positive part of the sine wave of the absolute voltage is repeated at a 100 Hz cycle.

FIG. 5B shows a repeated phenomenon of discharge of a fluorescent lamp. The fluorescent lamp starts discharging when the absolute value of the power supply voltage exceeds a certain value, that is, VTH in (a), and VTH
Discharge is stopped when the following occurs, so as shown in FIG.
The light emission amount changes in the cycle of 00 Hz.

FIG. 5C shows a change in the amount of charge accumulated in the image pickup device every 1 V (vertical scanning period). The image sensor repeats charge accumulation every 1 V, that is, every 60 Hz.

Therefore, in the period of V1 shown in FIG. 7C, the fluorescent lamp is discharged almost twice, while V2 is discharged.
1 time and 2/3 times during the period of, and 1 time and 1 time during the period of V3
Since the amount of light changes such as three times, the accumulated charge also changes as shown in (c).

The flicker detection circuit 115 shown in FIG.
The level change of the image pickup signal as shown in (c) may be detected, or the component of 20 Hz which is the light amount change cycle of FIG. 5 (c) may be extracted using a bandpass filter or the like.

If the flicker signal is the former, the main body microcomputer 114 detects the signal change period to determine the presence or absence of flicker. If the level signal of a specific frequency component is the flicker signal as in the latter case, the main body microcomputer 114. Then, it is determined whether or not the level of the flicker signal is equal to or higher than a predetermined level, and the presence or absence of flicker is determined.

The video signal processed by the camera signal processing unit 112 in FIG. 1 is stored in the field memory 132,
The memory control / interpolation circuit 133 controls the memory to read out the stored image, and outputs an enlargement signal enlarged in the vertical direction and the horizontal direction while performing interpolation between scanning lines and between pixels.

Under the control of the memory control / interpolation circuit 133, the enlarged signal read from the field memory 132 is again subjected to color processing and the like in the camera signal processing unit 112 and converted into a standard TV signal.

The memory control / interpolation circuit 133
The control is performed according to the enlargement ratio information from the electronic zoom control unit 134 in the main body microcomputer 114. The electronic zoom magnification information from the electronic zoom 134 is sent to the lens microcomputer 116.

The distance measuring frame size control unit 142 in the lens microcomputer 116 changes the size of the distance measuring frame based on the enlargement ratio information sent from the camera body 114 (which will be described later in detail with reference to FIG. 3). The size information is sent to the AF signal processing circuit 113 through the main body microcomputer 116.

Next, the AF signal processing circuit 11 will be described with reference to FIG.
3, the AE signal processing circuit 131 will be described in detail.
The red (R), green (G), and blue (B) image sensor outputs amplified by the amplifiers 109, 110, and 111 to the optimum levels are respectively A / D converters 206, 207, and 208.
Is converted into a digital signal by the camera signal processing circuit 112.
To the amplifiers 209 and 21 respectively.
The signal is appropriately amplified by 0, 211, and added by the adder 212 to form the luminance signal S5.

The luminance signal S5 is supplied to the bandpass filter 21.
3 to extract only the high frequency component whose signal level changes according to the focus state, and the gate circuit 214 extracts a scan line in a specific image area (area in the ranging frame) in the screen. Only the signal is gated, the peak hold circuit 215 holds the peak, and the peak value S6 of the focus signal is transferred to the lens microcomputer 116 through the main body microcomputer 114 upon completion of the gate processing in one field, and the peak hold circuit 215 is initialized. It

The ON / OFF control of the gate circuit 214 is controlled by the gate timing generation circuit 222 and the gate pulse control circuit 216, and based on the information S10 from the distance measurement frame size control section 142 in the lens microcomputer 116, the main body The microcomputer 114 determines the capture start position CD1 and the end position IR1 of the ranging frame as indicated by reference numeral 302 in FIG. 3, and ON / OFF control of the gate circuit is performed based on the information S12.

On the other hand, the luminance signal S5 is the AE signal processing circuit 1
It is input to 31. As the photometric signal input to the AE signal processing circuit 131, the average photometric signal S7a for detecting the entire image area as shown in FIG. 4A and only the central portion of the image area as shown in FIG. 4B are detected. It is divided into the center-weighted photometry signal S7b, weighted by weighting circuits 217 and 219, respectively, and added by the adder 221 to obtain a photometric evaluation value S8, which is the exposure control calculation unit 23 in the AWB / exposure control unit 135.
Sent to 1. Here, the ON / OFF timing of the gate circuit 218 that performs center-weighted photometry and the control of the weighting ratio are performed based on the information from the exposure control calculation unit 231.

The exposure control operation will be described below by taking the exposure control in the program mode as an example. There are a diaphragm mechanism, an AGC, an electronic shutter, and the like as control parameters that determine the exposure, and data in which each parameter is set for each program mode according to the subject and the shooting situation is stored in the exposure control unit 135 in a look-up table (LUT). LUT1 corresponding to program mode 1 for each program mode
(227), LUT2 corresponding to program mode 2
(228), LUT3 corresponding to program mode 3
(229), LUT4 corresponding to program mode 4
(230).

Further, the AWB / exposure control unit 135 calls the LUT data control unit 226 for the data of the look-up table corresponding to the program mode set by the program mode changeover switch unit 138, and controls each parameter based on the data. The program mode becomes possible with.

For example, when the movement of the subject is fast, the electronic shutter control section 224 controls the image pickup element (CCD) drive circuit 136 so that the electronic shutter for controlling the storage time of the image pickup element is set in preference to the high speed. By doing so, it becomes possible to set the shooting mode with excellent dynamic resolution, and the so-called "sport mode" can be set.

Further, an aperture drive command is delivered from the aperture control section 225 to the lens microcomputer 116, the aperture mechanism is preferentially set to the open side, and exposure control is performed using other parameters, whereby the depth of field becomes shallow. The so-called "portrait," which has the effect of blurring the background and is suitable for shooting people
"Mode" can be set.

In this way, it is possible to realize the optimum shooting for the shooting situation.

Further, in the AE signal processing circuit 131, by controlling the photometric distribution by setting the detection area and the detection position of the video signal for exposure control set by the gate pulse control circuit 220, more optimal photographing can be performed. And

For example, so-called average photometry in which the entire image area is detected as shown in FIG. 4A and exposure control is performed so that the detection signal has a constant level, or in the image area as shown in FIG. 4B. It is possible to perform center-weighted photometry in which only the central portion is detected and exposure is controlled so that the detection signal has a constant level.

Further, in the AE signal processing circuit 131, the weighting circuits 217 and 219 respectively weight the detection data of the entire video area and the detection data of the central emphasis area,
By performing exposure control based on the detection data obtained by adding each data at a fixed ratio, it is possible to perform exposure control by photometry that combines average photometry and center-weighted photometry.

By changing the setting of each weighting ratio in each program mode according to the subject and the shooting condition,
More optimal exposure control can be performed by taking advantage of each photometry.

For example, when the main subject is illuminated by a spotlight and the surroundings are dark, or when the subject is backlit, the weighting of the center-weighted photometry is increased and the ratio to the average photometry is adjusted so that only the main subject is displayed. Without this, it is possible to perform proper exposure control with a good balance even for a subject such as the surrounding background.

Further, as shown in FIG. 4 (c), the screen is divided, and the image detection is performed in each area, and the area of the detection data used for the exposure control in each program mode is restricted or weighted according to the subject and the shooting condition. By changing the, you can achieve fine exposure control.

An example of the automatic focus adjustment control method for a certain lens unit will be described with reference to FIG. The flowchart shown in FIG. 6 shows the lens microcomputer 11 in the lens unit.
6, when the zoom operation is not performed, the AF /
The algorithm of the automatic focus adjustment operation of the computer zoom control program 117 is described.

In the figure, reference numeral 601 indicates the start of AF control processing. First, in the processing of 602, a wobbling operation for determining a hill climbing direction is performed. Here, the wobbling operation will be described with reference to FIG.

FIG. 7 is a diagram showing how the AF evaluation value level 701 changes when the focus lens is moved from infinity to the closest distance with respect to a certain subject, where the horizontal axis is the focus lens position and the vertical axis is the vertical axis. Is set to the AF evaluation value level.

At the in-focus point, the AF evaluation value reaches the maximum level 7
The focus lens position is 7
08), the focus lens position is controlled so that the AF evaluation value level is always maximized.

Then, the focus lens is slightly vibrated to determine whether the in-focus point is on the closest side or the infinity side.
The wobbling operation is performed in order to judge from the fluctuation of the signal level at that time.

In the wobbling operation, while the focus lens is being finely driven, the AF evaluation value is fetched to determine whether the focus is currently in focus or out of focus (whether it is front focus or rear focus when out of focus). Is an operation for determining.

For example, when the current focus position is on the infinity side with respect to the in-focus point (position 709), the wobbling operation is executed and the lens is finely driven from the infinity direction (as shown by 703, the focus lens). The position is moved: the time axis is from the top to the bottom with respect to the paper surface), and the level change of the AF evaluation value obtained at that time is 704.

On the other hand, when the focus lens position is on the closest side to the in-focus point (position 710), when the lens is finely driven as indicated by 705, the level change of the AF evaluation value is 706. Can be obtained.

Since the phase of the level change of the AF evaluation value is opposite between 704 and 706, by discriminating this,
The side where the focus lens is located with respect to the focal point, that is, the moving direction of the focus lens is known.

Further, when the lens is finely driven at the peak of the AF evaluation value 701 (711), the level change (712) of the obtained AF evaluation value has a small amplitude and a different shape, so that it is blurred. You can know whether it is in focus or not.

In wobbling near the in-focus point, blurring may be seen depending on the drive amplitude amount (α in FIG. 7) that minutely drives the focus lens. Therefore, it is necessary to set the minimum amplitude amount at which the evaluation value is sufficiently obtained. is there.

On the other hand, in the vicinity of the skirt of the mountain 701, even if the focus lens is finely driven, the amplitude of the AF evaluation value sufficient for determining the direction may not be obtained, so that the amplitude of the lens drive should be increased. It is desirable to keep it.

In the actual wobbling operation, 703,7
Instead of driving the lens sinusoidally as in 11, 705, for example, the focus lens at the position of 709 is α-driven in the infinite direction by 713 to capture the AF evaluation value (evaluation value level corresponds to 714), After that, the evaluation value is fetched at 715 which is driven in the close-up direction by twice as much α (the level corresponds to 716), and the level difference is set as the driving direction evaluation value,
When the driving direction evaluation value has a significant absolute value amount larger than the noise amount, it is determined that the direction should be climbed according to the sign of the driving direction evaluation value.

In wobbling at the position 702 near the in-focus point, the level of the driving direction evaluation value obtained may not be sufficient, but the difference between the evaluation value before starting wobbling and the AF evaluation value obtained during wobbling. It is possible to detect whether or not the focus is achieved because the quantity can be detected and the evaluation value level at this time is high. (Since the evaluation value level is high, the influence of noise components is small, and the significant signal change mentioned above is also It can be made smaller than the hillside.

Now, return to the flowchart of FIG. 60
The process of 3 is the result of the wobbling operation of the process of 602,
This is a process of determining whether the current shooting state is in focus or out of focus. When it is determined that the focus is in focus, the focus lens is stopped and the restart monitoring process routine from the process of 609 is performed. go.

If it is determined in 603 that the object is out of focus, 60
In step 4, the direction in which the in-focus point exists is determined by the wobbling operation, and hill climbing is executed in the direction of the determination result (60
5).

Reference numeral 606 is a determination as to whether or not the focus of the focus evaluation signal, that is, the vertex of the focus evaluation signal is exceeded. If the focus is not exceeded, the mountain climbing is continued, and if it is exceeded, the focus lens is returned to the vertex (processing of 607 and 608).

During this hill climbing operation, the shape of the mountain is constantly monitored, and the hill climbing speed is speed-controlled according to the shape (the hill climbing speed is fast in the vicinity of the hill and slowly as the peak is approached).

Since the subject may change due to panning or the like during the operation of returning to the apex, if the focus lens reaches the apex, whether the present position is the apex, that is, the in-focus point is determined. 6 to judge
Returning to the processing from 02, the wobbling operation is performed again.

If the in-focus state is determined in the processing of 603, the restart monitoring routine from 609 is performed. First, 6
At 09, the AF evaluation value level at the time of focusing is stored.

Next, the restart determination is made in the processing of 610.

This will be described in detail with reference to FIG. As shown in FIG. 7, it is assumed that the focus lens position is 708 and the AF evaluation value level at that time is 702. This 7
The level of 02 corresponds to the AF evaluation value level stored in the processing of 609 of FIG.

Now, it is assumed that the evaluation value level is lowered from 702 to 707 due to a change in the subject or the like. At this time, the determination as to whether or not to execute the restart is performed as follows.

When the evaluation value level is changed from the level 702 to the illustrated restart determination threshold value β or more, it is determined that the focus state is out, and the restart is executed. If the variation of the evaluation value is smaller than the restart determination threshold β, it is determined that the restart is not executed.

Now, let us return to the flowchart of FIG. 6 again. The result determined in the process 610 of FIG. 6 is determined in 611. In the case of non-restart, the focus lens is stopped as it is (612), the process returns to 610, and restart monitoring is performed again.

If it is determined in 611 that the system is restarted, 60
Returning to the processing of 2, the wobbling operation is performed again and the moving direction of the focus lens is determined. By repeating such an operation, the focus lens operates so as to constantly maintain the in-focus state.

In the loop of this automatic focus adjustment operation, the AF
Since the evaluation value is normally generated in synchronization with the vertical synchronization signal cycle, the AF control routine is also performed in synchronization with the vertical synchronization signal cycle accordingly.

This is to effectively use the latest focus signal information as much as possible in order to speed up the AF responsiveness.

The algorithm of the focus adjustment operation with a specific lens has been described above, but in the case of another lens,
By optimizing the degree of speed control, the amount of wobbling amplitude, the parameters used for focus determination / restart determination, etc., according to the characteristics of each lens, it can be applied to all lens units that can be mounted on any subject or object. It is possible to realize AF that stably focuses on the main subject under shooting conditions.

Next, the main body microcomputer 11 which is a feature of the present invention
A description will be given of how to use the shooting state information delivered from No. 4 to the lens unit side for AF control.

First, the lens drive timing and the AF evaluation value acquisition timing are determined according to the flicker presence / absence information (in the camera body without the flicker detection circuit, the presence / absence of flicker can be recognized from the color temperature information and the electronic shutter information). Is changed to remove the influence of flicker and prevent the malfunction of AF.

An example of the wobbling operation performed in the processing of 602 of FIG. 6 will be described with reference to FIG. FIG. 8 (a)
5B is an extension of the time axis of FIG. 5C, and the image pickup signal output from the image pickup element shows a periodic level change due to flicker.

FIG. 8C shows the change over time in the focus position when the normal wobbling operation is repeated. As shown in this figure, in the wobbling operation, the focus lens is first driven in the closest direction by a predetermined amplitude, and when the predetermined focus position 801 is reached, the drive is stopped and the image sensor is stored in a stable state (1 V period). , Next V
During the synchronization signal period, the video signal stored in the period V1 is read from the image sensor to obtain the AF evaluation value at the focus position 801.

Next, drive to the position 802 in the infinite direction,
Similarly, the AF evaluation value at the focus position 802 accumulated during the period V3 during the period V4 is obtained.

When wobbling as shown in FIG.
If there is flicker, the obtained AF evaluation value fluctuates under the influence of flicker, and it becomes impossible to correctly determine the direction in which the in-focus point exists.

Therefore, only when the flicker exists, FIG.
As shown in (b), the wobbling operation cycle is synchronized with the flicker cycle, and the AF evaluation values used for the direction determination are V1, V4, and V.
7, V10 ... or V2, V5, V8, V11 ... are V
The influence is eliminated by taking in the light at 3, V6, V9, V12 ...

In the figure, the periods V2 and V5 are taken in, but not only the evaluation value in the 1V period, but also V1 + V2 and V4 + V5.
You may judge it by combining such as.

Further, the wobbling operation cycle is shown in FIG. 9B with the cycle of 3V. To remove the influence of flicker, if the video signal output change cycle by flicker is a positive multiple,
It doesn't matter how much.

When there is a flicker in this way, control is performed as shown in FIG. 11B to remove the influence of the flicker and make a reliable direction determination.
The responsiveness of AF is improved by completing the wobbling operation as soon as possible as in (C).

Second is amplification factor information such as AGC. Figure 7
Although the driving direction evaluation value level above the noise level was made effective for the direction judgment in the wobbling operation, the amplification amount of the noise component changes depending on the amplification factor of AGC, so the driving direction evaluation value level that should be ignored is also amplified. It is changed according to the rate to prevent the AF from malfunctioning.

Third is the program mode information. Figure 6
During the hill climbing operation (605, 606) or during the restart determination (610, 611, 612), the exposure state changes when the program mode changes, and the AF evaluation value also changes, which causes a malfunction. Is as described in the section of the problem to be solved by the present invention.

As one means for solving this problem, when the program mode is changed, the process returns to the processing from 602 in the flowchart of FIG. 6, the processing from the wobbling operation is performed again, and it is driven in the wrong direction to cause blurring. It prevents it from being triggered.

FIG. 9 shows an improved algorithm of the flowchart of FIG. 6 in that case. Although detailed description is omitted, the process 100 is included in the processes 605 and 610 of FIG.
1, 1002, 1003, and 1004 are added, and when a change in the program mode is detected, the process waits until the exposure state stabilizes, and then the process starts again from the wobbling operation.

In the series of processes, the waiting time counter C when it first reaches 1002 does not exceed the predetermined value C0 as the waiting time because the RAM is cleared by the initialization operation of the lens microcomputer 116 and the like. Absent.

Fourth, there is read cycle information at the time of slow shutter. A at 1Vsync at slow shutter
The F evaluation value cannot be obtained. For example, when the slow shutter speed is 1/15, the F evaluation value can be obtained only once every 4 vsync. Therefore, assuming that the AF evaluation value is updated every V, the AF control as shown in FIG. 6 is performed. If so, there is no difference in the evaluation value level of the wobbling result even though it is originally out of focus, so it was erroneously determined to be in focus, and blurring sometimes stopped.

In order to prevent this, it is assumed that the AF evaluation value is updated only in the reading cycle during the slow shutter, and wobbling, mountain shape determination during hill climbing, and restart operation are performed in synchronization with the reading cycle. , It prevents malfunction.

Fifth is image enlargement ratio information such as electronic zoom. This will be described with reference to FIG. In the figure, reference numeral 301 denotes a shooting screen, and 302 denotes a distance measuring area (distance measuring frame) for extracting the AF evaluation value already described.

[0135] The subject 3 at a relatively short distance is now on the shooting screen.
It is assumed that there is a subject 305 at a long distance from 04. In the present embodiment, the AF evaluation value is the peak value of the high frequency component of the video signal in the distance measurement frame, so that the 305 subjects behind are three.
When the brightness is higher than that of the object of No. 04, the AF control is performed to focus on the object of No. 305.

Now, it is assumed that the area indicated by 302 is enlarged as shown in FIG. 3B by the electronic zoom or the like. At this time, the screen of the monitor or the like seen by the photographer is as shown in FIG.
04 is enlarged and looks like 306 (the display on the monitor is as shown in (b) of the same figure, but the screen imaged by the image sensor remains as shown in (a) of the figure).

At this time, if the AF distance measuring frame remains at the size of 302, there is a possibility of focusing on the subject 305 that has not moved to the monitor. In this case, the photographer sees the image on the monitor. The screen will be blurred.

In order to solve such a problem, the size of the distance measuring frame is changed according to the electronic zoom magnification ratio information. In this case, for example, 303 is used as the distance measuring frame for electronic zoom.

By changing the size of the distance measuring frame according to the image magnification information in this way, it is possible to realize the AF performance in which the main subject intended by the photographer is not missed.

By the way, since the subject is magnified during the electronic zoom and the AF evaluation value varies greatly due to changes in the subject, camera operation, camera shake, etc., it is better to set the AF frame as large as possible. Is desirable from the standpoint of stability (in this case, the enlarged screen size is set to be the distance measurement frame).

Further, due to the enlargement of the subject, even a blur within the depth of field may be seen. Therefore, for example, the size of the minute drive amount α of the focus lens in the wobbling operation is usually set to It is desirable to make it smaller than time.

The size of the distance measuring frame described above can be changed according to the selected program mode, which is useful for photographing in which the intention of the photographer is further reflected. For example, in portrait mode, the aim is to blur the background, so the main subject is in the center of the screen and is in a bust-up state to some extent. Is better.

In the landscape mode for landscape photography, the upper part of the screen is mostly the sky, and the target object is often located on the lower side of the screen. Therefore, the distance measuring frame should be focused on the lower side of the screen. It is desirable to use a larger distance measuring frame so that the subject does not move in and out of the distance measuring frame due to camera shake (there is a case where the subject moves in and out of focus).

Up to this point, a typical example has been described as the information on the photographing state delivered from the camera body to the lens unit. However, in addition to the above contents, other camera signals such as gamma correction and aperture state can be obtained. Any information indicating the shooting state such as the processing state may be passed to the lens unit.

The case where the AF evaluation value is delivered from the camera body to the lens unit has been described above as an example. However, the present invention can be applied if the lens control means such as focus adjustment is provided in the lens unit, and the AF evaluation value can be obtained. Instead of delivering, the image signal itself is delivered, and the AF signal processing circuit 113 is provided in the lens unit to perform AF in the lens unit.
The evaluation value may be generated.

[0146]

As described above, according to the first and second aspects of the present invention, the information regarding the image pickup state on the image pickup apparatus main body side is transmitted to the lens unit side. Even if a control unit such as a focus adjustment device is provided in the lens unit, the shooting state can be accurately recognized, and no matter what characteristic or function the lens unit is attached to, it is captured from the main body of the imaging device. (EN) An image pickup device and a lens unit in an interchangeable lens system capable of stably focusing on a target main subject under all subjects and shooting conditions, since optimum control can be performed on the lens unit side based on control information. You can

Further, according to the invention described in claims 3, 4, 5, 6, and 7, the color temperature information and the exposure information (accumulation of the image pickup element) in the image pickup screen are transferred from the image pickup apparatus main body side to the lens unit side. Time, amplification factor that controls the level of the image pickup signal, aperture information, etc.) are supplied, so information such as whether the shooting environment is indoors or outdoors and the type of lighting is supplied to the lens unit side. It is possible to perform optimal control according to the shooting environment for various functions such as AF on the lens unit side.

Even if there is no flicker detecting means, the color temperature information and the electronic shutter information, which are known by the white balance control and the exposure control, are transferred to the lens unit as the imaging state information so that the photographing environment is indoors or outdoors. On the other hand, the presence or absence of flicker can be recognized based on whether or not the shutter speed is 1/60, and this makes it possible to synchronize the lens driving and the AF evaluation value acquisition timing with the flicker cycle and remove the influence of flicker. As a result, it is possible to realize an interchangeable lens system having a high-performance AF that is not affected by the illumination conditions at the time of shooting and has excellent responsiveness.

By passing the amplification factor information for amplifying the image pickup signal of AGC or the like as the image pickup information, the focus adjustment control based on the change of the AF evaluation value above the noise level becomes possible. However, it is possible to focus accurately.

According to the invention of claim 8 in the present application, since the information of the photographing program mode is supplied from the image pickup device side to the lens unit side, various kinds on the lens unit side suitable for each program mode are provided. It becomes possible to control.

As a result, it is possible to recognize that the change in the AF evaluation value level at the timing of the mode change is not due to the change in the subject, and it is also possible to recognize whether or not the mode is aimed at the shooting effect, so that the blurring can be stably prevented You can achieve comfortable AF performance.

According to the invention of claim 9 of the present application, since the slow shutter read cycle information is supplied from the image pickup apparatus main body side to the lens unit side, the update timing of the AF evaluation value can be recognized. Thus, high-performance slow shutter AF can be realized.

According to the tenth aspect of the present invention, since the image magnification information of the subject in the image magnification changing means is supplied from the image pickup apparatus main body side to the lens unit side, the image pickup screen by the electronic zoom is provided. Since the enlarged area of can be recognized, the target subject can be quickly focused.

According to the invention described in claim 11 of the present application, the intensity of light emission, the lighting / flashing cycle, from the image pickup apparatus main body side to the lens unit side depending on the frequency of the power source of the illumination means for illuminating the subject. Since the information regarding the flicker is supplied, it is possible to remove the influence of the flicker by synchronizing the lens driving and the fetch timing of the AF evaluation value with the flicker cycle when the flicker is present. As a result, it is possible to realize an interchangeable lens system having a high-performance AF that is not affected by the illumination conditions at the time of shooting and has excellent responsiveness.

According to the twelfth aspect of the present invention, no matter what characteristic or function the lens unit is attached to, the optimum lens unit side can be obtained based on the control information fetched from the image pickup apparatus main body side. Since the AF control can be performed, it is possible to provide an imaging device and a lens unit in an interchangeable lens system that can stably focus on a target main subject under all subjects and shooting conditions.

According to the thirteenth aspect of the present invention, further, from the lens unit side, the size information of the distance measuring frame in the image pickup screen suitable for the operating state on the lens unit side is sent to the image pickup apparatus main body. Since the supply is performed, it is possible to realize the optimum control for each individual lens unit regardless of which lens unit is mounted, and also it is possible to optimize the control on the imaging device side.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment in which the present invention is applied to an interchangeable lens type video camera.

FIG. 2 is a block diagram showing details of internal configurations of an AF signal processing circuit 113, an AE signal processing circuit 131, and a main body microcomputer 114 in the camera signal processing circuit 112 according to the present invention.

FIG. 3 is a diagram for explaining electronic zoom and control of a distance measurement frame associated with the electronic zoom operation.

FIG. 4 is a diagram for explaining a setting operation of a photometric area.

FIG. 5 is a diagram for explaining a change in image pickup signal level due to flicker.

[FIG. 6] AF by the main body microcomputer 114 in the camera main body
It is a flow chart for explaining control.

FIG. 7 is a diagram for explaining a wobbling operation for determining the drive direction of the focus lens in the AF operation.

FIG. 8 is a diagram for explaining a wobbling operation in consideration of measures against flicker.

FIG. 9 is a block diagram showing a typical configuration of a conventional automatic focus adjustment device.

FIG. 10 is a flowchart showing another embodiment of the present invention.

[Explanation of symbols]

 105 Focus Lens 106 Image Sensor 107 Image Sensor 108 Image Sensor 112 Camera Signal Processing Circuit 113 AF Signal Processing Circuit 114 (Camera) Main Unit Microcomputer 115 Flicker Detection Circuit 116 Lens Microcomputer 117 AF / Computer Zoom Control Circuit 118 Motor Control Circuit 119 Lens Cam Data 120 Aperture control unit 125 Focus motor 126 Motor driver 130 AWB signal processing circuit 131 AE signal processing circuit 132 Field memory 133 Memory control / interpolation circuit 134 Electronic zoom control unit 142 Distance measuring frame size control unit

Claims (13)

[Claims] 1. An image pickup device in which a lens unit including an image pickup lens and a control unit for controlling the image pickup lens is detachable, the image pickup unit converting an image formed by the image pickup lens into an image pickup signal and outputting the image pickup signal. An image pickup apparatus comprising: a control unit configured to transmit information regarding an image pickup state of the image pickup unit to the lens unit. 2. A lens unit attachable to and detachable from an image pickup apparatus main body, which comprises an image pickup means for photoelectrically converting incident light and outputting an image pickup signal, the image pickup lens, and a control means for controlling the image pickup lens. A unit for taking in information on an image pickup state of the image pickup unit from the side of the image pickup apparatus to change the operation of the control unit. 3. The image pickup apparatus according to claim 1, wherein the information regarding the image pickup state is color temperature information within an image pickup screen. 4. The image pickup apparatus according to claim 1, wherein the information regarding the image pickup state is exposure information. 5. The image pickup device according to claim 4, wherein the image pickup device includes an image pickup device and a storage time control device that controls a storage time of the image pickup device, and the exposure information is information regarding a storage time of the image pickup device. A characteristic imaging device. 6. The image pickup means according to claim 4, wherein the image pickup means includes an amplifier having a variable amplification factor for controlling a level of the image pickup signal, and the exposure information is amplification factor information of the amplifier. Imaging device. 7. The image pickup unit according to claim 4, further comprising a diaphragm mechanism for controlling an incident light amount,
The image pickup apparatus, wherein the exposure information is aperture information of the aperture mechanism. 8. The image pickup means according to claim 4, further comprising: shooting mode setting means capable of setting a plurality of shooting modes that can be arbitrarily selected according to shooting conditions, and the exposure information is provided for each of the shooting modes. An image pickup apparatus, which is information on a program mode for controlling a camera signal processing state such as an exposure state of the image pickup means, gamma correction, and aperture correction. 9. The so-called slow shutter read cycle information according to claim 5, wherein the exposure information is a so-called slow shutter read cycle information in which the image pickup signal is read out intermittently by lengthening the accumulation time of the image pickup element to an integral multiple of the normal time. An image pickup apparatus characterized by the following. 10. The image pickup apparatus main body according to claim 1, further comprising an image magnification changing unit that electronically enlarges or reduces a part of an image pickup screen, and the information regarding the image pickup state is the image magnification changing unit. An image pickup apparatus, which is image magnification information of a subject in. 11. The image pickup apparatus according to claim 1, wherein the image pickup state information is information regarding intensity of light emission and lighting / flashing cycle depending on a frequency of a power source of an illumination unit that illuminates an object. . 12. The image pickup apparatus according to claim 1, further comprising a focus control unit that changes a control method for adjusting the focus of the image pickup lens according to the image pickup state information. 13. The distance measurement frame size control means for setting the size of the distance measurement frame within the image pickup screen, and the distance measurement frame size information set by the distance measurement frame size control means according to claim 2. A lens unit comprising means for supplying to the main body.