JP2001324672A - Automatic focusing control method and automatic focusing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AF control method and an AF device capable of normally performing AF operation by acquiring an exact AF evaluated value for a subject having much smear at high speed. SOLUTION: After subtracting a smear component from output data from a solid- state image pickup element, the arithmetic processing of the AF evaluated value is performed. Then, the arithmetic operation of the AF evaluated value is performed to the output data (including the smear component) from the solid-state image pickup element and smear data including only the smear component respectively and separately, and the AF evaluated value of the smear data is subtracted from the AF evaluated value of the output data (including the smear component) so as to obtain the AF evaluated value from which the influence of the smear is eliminated. A system in which the smear data is acquired from an idly transfer part out of an AF area and a system in which the smear data is acquired from the same area as the AF area can be switched, so that the smear data acquiring method is switched in accordance with photographing circumstances (for example, bright time/dark time). In the case of detecting the AF evaluated value at each lens position in the midst of moving a lens, the smear detecting operation is intermittently inserted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus (AF) technique applied to a digital camera and the like,
In particular, an AF evaluation value is calculated based on a signal obtained from a solid-state imaging device, and focusing control is performed according to the calculation result.
The present invention relates to an F control method and an apparatus thereof.

[0002]

2. Description of the Related Art When a high-luminance subject such as the sun or a light is photographed by a camera using a solid-state imaging device such as a CCD,
A strip-shaped bright line appears in the vertical direction of the shooting screen. Such a phenomenon is called a smear phenomenon, and when charges generated in each photodiode (photoelectric conversion element) of the surface imaging device are transferred through a transfer path and read out, charges of a large incident light amount overflow into the transfer line. Or the incident light itself leaks into the transfer line to generate charges on the transfer line.

Japanese Patent Application Laid-Open No. Hei 5-7335 proposes a method of obtaining accurate AE photometric data by subtracting a smear component from CCD output data in automatic exposure control (AE).

[0004]

However, the above publication is directed to photometric data for AE control, and does not mention autofocus (AF) control. The inventors of the present application focused on the influence of smear on the AF control and analyzed the technical problem as follows.

FIG. 20 is a block diagram of an AF processing system applied to a general digital camera. Light incident on a CCD solid-state imaging device (hereinafter, referred to as a CCD) 222 through a lens 220 is photoelectrically converted by each photosensor of the CCD 222. The output of the CCD 222 is applied to an analog processing unit 224, where it is subjected to correlated double sampling (CDS) processing and color separation processing into R, G, and B color signals. The signal level is adjusted.

The output signal of the analog processing unit 224 is A /
After being digitized by a D converter (ADC) 226, it is passed through a band pass filter (BPF) 228. The CPU 230 detects the contrast of the subject image based on the output signal of the bandpass filter 228, and controls the motor 232 to control the lens 22 according to the detection result.
Move 0 to the in-focus position. The timing generator (TG) 234 has a CCD
A timing signal is provided to the analog-to-digital converter 222, the analog processing unit 224, and the A / D converter 226, and the circuits are synchronized by the timing signal.

As shown in FIG. 21A, when an image including a light source 240 of high luminance is photographed, a vertical stripe-shaped bright line 242 is generated due to a smear phenomenon. An area surrounded by a dotted line indicated by reference numeral 244 in the drawing is a target area for AF evaluation value calculation (hereinafter, referred to as an AF area).
20 when the smear bright line 242 exists in FIG.
The signal waveforms at points A and B in FIG.
(B) and (c) are obtained. Therefore, the CPU 230
In the evaluation value detection performed by (1), the edge of the smear signal is detected, and a problem arises that the original main subject (in this case, the person 246) cannot be focused.

The present invention has been made in view of such circumstances, and an AF control method and an AF control method capable of acquiring an accurate AF evaluation value at high speed with respect to a subject having much smear and performing an AF operation normally. An object of the present invention is to provide an AF device.

[0009]

In order to achieve the above object, an automatic focus control method according to the present invention performs a process of subtracting a smear component from output data of a solid-state imaging device, and performs a process based on the data after the subtraction process. An AF evaluation value is obtained by a predetermined calculation method, and the lens is moved to a focusing position based on the obtained AF evaluation value.

According to another aspect of the present invention, there is provided an autofocus control method, wherein an AF evaluation value is calculated by a predetermined calculation method based on the output data without performing processing for removing a smear component from the output data of the solid-state imaging device. On the other hand, smear data containing only smear components is obtained from the solid-state imaging device, an AF evaluation value is obtained by a predetermined calculation method based on the smear data, and the smear data is obtained from the AF evaluation value obtained from the output data. A process of subtracting the calculated AF evaluation value is performed, and the lens is moved to a focus position based on the AF evaluation value obtained by the subtraction process.

A mode in which an AF area for which an AF evaluation value is to be calculated in an effective pixel area (that is, an image area) of a solid-state imaging device is determined in advance, and an AF evaluation value is calculated based on data of the predetermined AF area. Is preferred. Unnecessary information other than the AF area can be swept away before reading from the solid-state imaging device, or can be discarded after reading, whereby the processing can be speeded up.

As one mode of the present invention, a reading method for acquiring the smear data from an idle transfer portion outside the AF area and a reading method for acquiring the smear data from the same area as the AF area are selectively performed. There is also a mode in which switching is possible.

By properly using the smear detection method according to the photographing situation (for example, based on whether the image is bright or dark), it is possible to detect the AF evaluation value at high speed and with high accuracy. In order to obtain smear data from the same area as the AF area, a transfer operation in which reading of signal charges generated in each light receiving unit of the solid-state imaging device is prohibited, that is, a so-called “empty read driving” is performed.

According to another aspect of the present invention, there is provided an autofocus control method for detecting an AF evaluation value based on output data of a solid-state image sensor at each lens position while moving a lens, the method comprising: While repeating the operation of driving the image sensor to obtain the AF photometric data including the image signal component and the smear component of the subject, the operation of intermittently inserting the operation of obtaining the smear data including only the smear component at a predetermined rate. Then, an AF evaluation value from which the influence of smear has been removed is obtained using the obtained AF photometric data and smear data, and the lens is moved toward the in-focus position based on the AF evaluation value. .

As a method for detecting smear data,
The data may be represented by data obtained from an idle transfer portion outside the F region, may be obtained from the same region as the AF region, or may be obtained from a part of the idle transfer portion within the AF region. Is also good.

In order to apply an apparatus embodying the above method invention, an autofocus apparatus according to the present invention comprises a plurality of light receiving sections having a photoelectric conversion function arranged in a plane, and a signal charge generated by each light receiving section is converted. A solid-state imaging device having a vertical transfer path and a horizontal transfer path for transferring, and an image signal including a signal charge component and a smear component of a subject is output from the solid-state imaging device, and a smear signal including only a smear component is output. A drive circuit unit that drives the solid-state imaging device so as to output the first solid-state imaging device; and a first storage unit that stores AF photometry data including information on a signal charge component and a smear component of a subject acquired through the solid-state imaging device. Second storage means for storing smear data including only information on smear components obtained via the solid-state imaging device, and the smear data from the AF photometric data. A seeking and calculating means for performing a process of subtracting the over data, the AF evaluation value by a predetermined calculation method based on the resulting data of the subtraction processing by the arithmetic means
It is characterized by comprising: an F evaluation value detecting means; and a lens control means for moving a lens to a focusing position based on the AF evaluation value obtained by the AF evaluation value detecting means.

According to another aspect of the present invention, there is provided an autofocus apparatus, wherein a plurality of light receiving units having a photoelectric conversion function are arranged in a plane, and a vertical transfer path for transferring signal charges generated in each light receiving unit; A solid-state imaging device having a horizontal transfer path, and the solid-state imaging device outputs an image signal including a signal charge component and a smear component of a subject from the solid-state imaging device, and outputs a smear signal including only the smear component. And a first AF for obtaining an AF evaluation value by a predetermined calculation method based on AF photometry data including information on a signal charge component and a smear component of a subject acquired via the solid-state imaging device. An AF evaluation value is calculated by a predetermined calculation method based on evaluation value detection means and smear data including information on only a smear component obtained via the solid-state imaging device. Subtracting the AF evaluation value of the smear data obtained by the second AF evaluation value detection means from the AF evaluation value obtained by the second AF evaluation value detection means. It is characterized by comprising arithmetic means for performing processing, and lens control means for moving a lens to a focus position based on the AF evaluation value obtained by the subtraction processing by the arithmetic means.

According to another aspect of the present invention, there is provided an autofocus apparatus, wherein a plurality of light receiving units having a photoelectric conversion function are arranged in a plane, and a vertical transfer path for transferring signal charges generated in each light receiving unit. And a solid-state imaging device having a horizontal transfer path, and the solid-state imaging device outputs an image signal including a signal charge component and a smear component of a subject from the solid-state imaging device, and outputs a smear signal including only a smear component. While repeating a drive circuit unit for driving the element and an operation of driving the solid-state imaging element at each lens position while moving the lens to obtain AF photometry data including an image signal component and a smear component of the subject, The operation of acquiring the smear data containing only the smear component is intermittently inserted at the ratio of, and the obtained AF photometric data and the smear data are used to obtain the smear data. AF evaluation value detection means for obtaining an AF evaluation value from which sound has been removed, and lens control means for moving a lens toward a focus position based on the AF evaluation value obtained by the AF evaluation value detection means. It is characterized by:

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

First, the structure of the CCD image pickup device will be outlined. Figure 1 shows an interline (IL) type CC
It is a conceptual diagram of D imaging device. Although the number of pixels is reduced in the figure for convenience of description, an actual device has hundreds of thousands to millions of pixels. As shown in the figure,
In the IL-type CCD imaging device 10, photosensors (for example, photodiodes) 12 having a photoelectric conversion function are arranged in a matrix, and signal charges accumulated in each photosensor 12 are vertically transferred through a transfer gate 14. The data is read out to the transfer path 16. The transfer gate 14 is controlled by a pulse provided from a CCD driver (denoted as 34 in FIG. 2). When a pulse is applied to the transfer gate 14, the charges accumulated in the photosensor 12 are transferred to the vertical transfer path 1
Moved to 6.

The vertical transfer path 16 vertically transfers signal charges in the downward direction in FIG. 1 by a vertical transfer pulse applied from the CCD driver 34. Further, this imaging device has a so-called electronic shutter function of controlling the charge accumulation time (shutter speed) of each photosensor 12 by a shutter gate pulse.

After the signal charge accumulated for a predetermined charge accumulation time indicated by the electronic shutter value is read out to the vertical transfer path 16, the signal charge is transferred to the horizontal transfer path 20 provided at the lower end of the vertical transfer path 16. (Downward in FIG. 1). The signal charges transferred to the last stage of the vertical transfer path 16 are sequentially transferred to the horizontal transfer path 20 every one horizontal drive period (1H).

The horizontal transfer path 20 transfers signal charges to the output section 22 by a horizontal transfer pulse applied from the CCD driver 34. The output unit 22 detects the charge of the signal charge and outputs the signal charge to the output terminal 24 as a signal voltage. Thus, an image signal is output every one vertical drive period (1 V). Although the vertical transfer path 16 and the horizontal transfer path 20 are shielded from light by a light blocking member (not shown), charge leaks from the photosensor 12 into the vertical transfer path 16 due to incidence of an excessive amount of light, and at the same time, the transfer path itself Exposure causes smearing.

FIG. 2 is a block diagram of an electronic camera to which the AF device of the present invention is applied. The electronic camera 30 employs the IL-type CCD imaging device 10 described with reference to FIG. 1 as an imaging device.

The photographing lens 32 is composed of one or a plurality of lenses, and may be a lens having a single focal length (fixed focus) or a focal length such as a zoom lens or a telephoto / wide-angle bifocal switching type lens. It may be variable. Shooting lens 3
The light passing through 2 enters the CCD 10. CCD10
The subject image formed on the light receiving surface of each photo sensor 12
As a result, the signal charges are converted into signal charges in an amount corresponding to the incident light amount.

The signal charges accumulated for a predetermined time are transferred to the vertical transfer path 16 by a transfer gate pulse applied from the CCD driver 34, and then vertically transferred by applying a vertical transfer pulse. Then, the signal charges transferred to the final stage of the vertical transfer path 16 are transferred to the horizontal transfer path 20, horizontally transferred by application of a horizontal transfer pulse, and extracted as a signal voltage via the output unit 22.

For example, the CCD driver 34 operates in a 1 V period (1 field period = 1/60 in the case of the NTSC system).
The transfer gate pulse is output in synchronization with the vertical drive pulse (VD) having a cycle of (sec), and the image signal is read every 1 V period.

Based on the calculation result of the exposure value, the signal charge accumulated for a predetermined charge accumulation time indicated by the electronic shutter value is read by the transfer gate pulse.

The image signal read from the CCD 10 is
The signal is sent to the analog processing unit 36. Analog processing unit 36
Includes a sampling hold circuit, a color separation circuit, a gain adjustment circuit, and the like. The analog processing unit 36 performs correlated double sampling (CDS) processing and color separation processing into R, G, and B color signals. The signal level is adjusted (pre-white balance processing).

The signal output from the analog processing section 36 is converted into a digital signal by an A / D converter 38 and stored in a memory 40. The timing generator (TG) 42 includes a CCD driver 34, an analog processing unit 36, and an A / D converter 38 according to a command from the CPU 44.
, And a timing signal is provided to synchronize the respective circuits.

The data stored in the memory 40 is transmitted to the bus 4
6 to the signal processing unit 48. Signal processing unit 48
Is a digital signal processor (D) including a gamma correction circuit, a sharpness correction circuit, a contrast correction circuit, a luminance / color difference signal generation circuit, a white balance correction circuit, and the like.
SP), and processes an image signal in accordance with a command from the CPU 44.

The image data input to the signal processing section 48 includes a luminance signal (Y signal) and a color difference signal (Cr, Cb signal).
After being subjected to predetermined processing such as gamma correction, it is stored in the memory 40.

The image data stored in the memory 40 is C
The display memory 50 is read out according to the instruction of the PU 44 and displayed.
Sent to The data stored in the display memory 50 is
After being converted into a signal of a predetermined system for display (for example, a color composite video signal of the NTSC system), the signal is output to the display unit 54 via the D / A converter 52. As the display unit 54, a liquid crystal display, a TV monitor, or the like can be used.
Thus, the image content of the image data is output on the monitor of the display unit 54 on the monitor.

The image data in the memory 40 is periodically rewritten by the image signal output from the CCD 10, and the image signal generated from the image data is supplied to the display unit 54, so that the image captured by the CCD 10 can be read in real time. As a moving image or not in real time,
The image is displayed on the display unit 54 as a substantially continuous image. The photographer can confirm the photographing angle of view while viewing the screen of the display unit 54 or using an optical finder (not shown).

By pressing a release button included in the operation unit 56, a recording start instruction signal is issued, and in response to the reception of the instruction signal, capturing of image data for recording is started. When the mode for compressing and recording the image data is selected, the CPU 44 sends a command to the compression / expansion circuit 58, and the compression / expansion circuit 58 compresses the image data in the memory 40 according to JPEG or another predetermined format. I do. The compressed image data is recorded on the memory card 62 via the card interface circuit 60.

When a mode for recording uncompressed image data (non-compression mode) is selected, the compression processing by the compression / expansion circuit 58 is not performed, and the image data is stored in the memory card 62 without compression. Will be recorded.

In the electronic camera 30 of the present embodiment, a memory card is used as a means for storing image data. Specifically, for example, smart media (Solid-State Flop)
py Disk Card) is applied. The form of the recording medium is not limited to the above, but may be a PC card, a compact flash (registered trademark), a magnetic disk, an optical disk, a magneto-optical disk, a memory stick, or the like, and may be electronic, magnetic, optical, or any of these. Various readable and writable media can be used in accordance with a combination method. Signal processing means and interfaces corresponding to the medium used are applied. A configuration may be adopted in which a plurality of media can be mounted irrespective of different types or the same type of recording media.

In the reproduction mode, the image data read from the memory card 62 is expanded by the compression / expansion circuit 58 and output to the display unit 54 via the display memory 50 and the D / A converter 52.

The CPU 44 is a control section for controlling the circuits of the camera system. The CPU 44 includes storage means such as a ROM and a RAM (not shown).
The program processed by the U44 and various data necessary for control are stored, and the RAM is used as a work area when the CPU 44 performs various arithmetic processing and the like. CPU4
Reference numeral 4 controls the operation of a corresponding circuit based on an input signal received from the operation unit 56, and also controls display on the display unit 54, autofocus (AF) control, automatic exposure (AE) control, and the like.

That is, the CPU 44 calculates the AF evaluation value and calculates A based on the image signal output from the CCD 10.
Various calculations such as E calculation are performed, and based on the calculation results, the lens driving unit 64 including the focus motor is controlled to move the lens to the focusing position, and the diaphragm driving unit including the iris motor (not shown) is controlled. To set an appropriate aperture, and control the charge accumulation time of the CCD 10.

In the electronic camera 30, the A / D converter 3
8 is converted to a band pass filter (BPF) 6
6 to the CPU 44. The CPU 44
An AF evaluation value indicating the sharpness of the subject image is calculated based on a signal received from the PF 66, and a focus position is calculated based on the AF evaluation value. Then, the lens driving unit 64 is controlled according to the calculated focus position, and the photographing lens 32 is moved to the focus position. In the case of this example, the edge of the signal is detected by the band-pass filter 66 after the A / D conversion.
An embodiment in which D conversion is performed is also possible. By converting the CCD output into differential information by the band-pass filter 66, the data amount can be reduced.

The operation unit 56 is a block including instruction input means such as a release button, a mode selection dial, and up / down / left / right keys, and includes a push button switch, a dial, a lever switch, a slide knob, and the like. The present invention is not limited to the embodiment, and there is a mode in which a desired item is selected from a setting menu or a selection item displayed on the screen of the display unit 54 using a cursor, a pointer, a touch panel, or the like. The operation unit 56 may be provided in the camera body, or may be configured such that part or all of the operation unit 56 is separated from the camera body as a remote control transmitter.

Next, the electronic camera 3 configured as described above
A method of detecting smear at 0 will be described.

FIG. 3 is a timing chart showing a first embodiment of the smear detection method. As shown in the figure, AF photometric scanning for obtaining photometric data required for AF control is performed in synchronization with a vertical drive signal (VD). After the electric charge is stored for a predetermined time within the 1 V period, the readout processing of the stored electric charge is executed in the next 1 V period. Photo sensor 1
After all the stored charges of 2 are read out during the valid period, smear data is obtained by performing idle readout scanning at 1H (or several Hs).

This blank reading is performed during the blanking period.
This is performed for a portion where no subject signal is output, that is, one horizontal line (or several lines) outside the effective pixel area, and only a smear signal is detected. In the case of this method, all the smear components in the AF area are represented by the smear data of one line (or several lines) related to the blank reading. AF photometry is repeatedly performed a predetermined number of times.

FIG. 4 is a timing chart showing a second mode of the smear detection method. As shown in FIG. 4, there is a method in which the vertical transfer path 16 and the horizontal transfer path 20 are driven to read only the smear information from the entire AF area without reading out the accumulated charges. That is, photometry for smear is performed in the 1 V period, and in the next 1 V period, no pulse (transfer gate pulse: TG) is applied to the transfer gate 14 (without transferring the accumulated charges to the vertical transfer path 16), and the idle reading is performed. Acquire smear data by driving.

Normal AF photometry is performed during the idle readout period, and the signal charges accumulated during this period are read out during the next 1V period. In this way, the smear metering and the AF metering are alternately repeated to obtain smear data (data of only the smear signal) and AF metering data (data in which the smear signal is added to the subject signal). According to this method,
Since smear data is obtained from the entire AF area, more accurate smear AF correction can be performed.

FIG. 5 is a timing chart showing a third mode of the smear detection method. As shown in the drawing, there is also a mode in which the idle transfer section and the data section are alternately read every 1H during the data reading period of the AF photometry. Only the smear signal is obtained from the idle transfer unit, and the subject signal (including the smear signal) is obtained from the data unit.

A CCD driving mode for reading data of all pixels of one screen in two fields will be described as an example. In the moving image display mode, when reading out the signal charges of the subject image generated by the photosensor 12, an odd field ( In the first field), a transfer gate pulse is applied to the odd-numbered transfer gates 14 to read out signal charges from the respective photosensors 12 in the odd-numbered rows. A transfer gate pulse is applied to read out signal charges from the photosensors 12 in the even rows. As described above, signal charges are read from all the photosensors 12 of the CCD 10 in two fields.

On the other hand, in the AF photometry mode, in the first field, each of the photosensors 12 is arranged at every other row among the odd-numbered rows (first row, fifth row, ninth row, and so on). , And in the second field, the signal charge is read out from each photosensor 12 in every other even-numbered row (second row, sixth row, tenth row, and so on).

Thus, in the first field, the third
In the row, the seventh row, and the second field, no signal charges are read out from the photosensors 12 in the fourth row, the eighth row, and so on. And smear charges alternately exist, and signal charges (including smear components) and smear charges are alternately transferred to the horizontal transfer path 20 by the vertical transfer pulse.

The charges transferred to the horizontal transfer path 20 are sequentially transferred in the direction of the output section 22 by a horizontal transfer pulse.
In any of the fields, the output unit 22 alternately outputs an image signal corresponding to the signal charge and a smear signal (non-image signal) corresponding to the smear charge for each line. As a result, photometric information and smear information can be obtained simultaneously.

In this method, the smear correction is performed by reading out the signal line (including the smear component) and the smear line separately every 1H. These two lines are added in 1H. However, since reading is performed at 2H, the reading time is twice as long. In the case of AF control,
Since high-speed read processing is required, the following method is adopted to achieve high-speed read.

As shown in FIG.
When an area (AF area) 70 for which the F evaluation value is to be calculated is set at the center of the screen, the area outside the AF area 70 is a sweep-out area. Sweep area,
Are swept away at a high speed when reading out the signal charges, and are ignored in the evaluation value calculation. In FIG.
Is a high-intensity light source, 74 is a bright line by smear, and 76 is a main subject.

As shown in the timing chart of FIG.
The driving of the CCD 10 is performed in synchronization with the VD. The signal in the sweep area is discarded, and only in the AF area 70, the idle transfer section and the data section are alternately read every 1H. Thus, by limiting the read area to the AF area 70, the read speed required for the AF processing can be secured.

FIGS. 8 and 9 show further modifications of the smear detection method (third embodiment) described with reference to FIGS. In the example shown in FIG. 8, smear detection areas are defined adjacently above and below the AF area 70, and the outside of these smear detection areas is a sweeping area. The smear detection area can be set to an appropriate number of lines, one or more lines. The smear detection area is not limited to the upper and lower adjacent parts of the AF area 70 shown in FIG. Is also good.

Under the area setting shown in FIG. 8, the AF photometry operation as shown in FIG. 9 is performed. That is, the signal in the sweep area is swept away, and 1H in the smear detection area.
The idle transfer section and the data section are alternately read each time.
At this time, smear data is obtained by reading from the idle transfer unit. Then, in the AF area 70, normal read processing (processing of reading a subject signal after transferring signal charges to the vertical transfer path 16) is performed. In the AF area 70, the subject signal (including the smear component) is read without performing the sky readout.
Get the data of When the processing of the AF area 70 is completed, the idle transfer section and the data section are read every 1H in the smear detection area to obtain smear data. Subsequent signals in the sweep area are swept away.

For comparison, FIG. 10 shows FIGS. 6 and 7.
4 shows a timing chart of the smear detection method described in FIG. As is apparent from a comparison between FIGS. 10 and 9, FIG.
Performs smear detection and data detection every 1H in the AF area, and thus takes a long time to read. In contrast, in FIG.
Since smear detection is performed above and below the AF area (or somewhere in the video area), normal reading (only data detection) is possible in the AF area, and the reading speed is increased (t2≪).
t1) Yes.

Next, specific means to which the first mode of the smear detection method described with reference to FIG. 3 is applied will be described. FIG.
As shown in FIG.
Data for N lines corresponding to the F area 70 is stored in the first memory 81 shown in FIG. This N line is AF
It is called an evaluation value detection area. On the other hand, data for the first 1H of the idle read is stored in the second memory 82 shown in FIG. This one line is called a smear detection area.

Then, the smear area data stored in the second memory 82 is subtracted from the AF area data stored in the first memory 81, and the obtained data is used as an evaluation value calculation block 84.
To obtain a final AF evaluation value.

The above process will be described with reference to FIG. 13. The data of one horizontal line (data after A / D conversion of the CCD output) in the AF area 70 shown in FIG. The waveform is as shown in FIG. When this waveform signal is passed through a band-pass filter 66, at a point B in FIG.
An output waveform as shown in FIG. This data is
The area data is stored in the first memory 81 (memory for storing the AF area data).

On the other hand, the waveform of the data obtained from the smear detection area after the band pass filter 66 is shown in FIG.
As shown in (d), information on only the smear portion is included. This data is stored in the second memory 82 (smear area data storage memory) as smear area data.
Then, at point C in FIG. 12 after the processing of subtracting the smear area data from the AF area data, data of only the subject signal from which the smear signal has been removed is obtained as shown in FIG. By inputting the image signal from which the smear component has been removed to the evaluation value calculation block 84 and calculating the AF evaluation value based on the image signal, an accurate evaluation value excluding the influence of smear can be obtained.

FIG. 14 shows a basic block of the evaluation value calculation. In the figure, reference numeral 87 denotes an absolute value circuit, and reference numeral 88 denotes an integrating circuit. 14A, 15B, and 15C show signal waveforms at points E, F, and G in FIG. The input signal shown in FIG.
To obtain a signal shown in FIG. The obtained signal (b) is converted into an absolute value by the absolute value circuit 87, thereby obtaining the absolute value data shown in (c). Then, the AF evaluation value is obtained by integrating the absolute value data in units of time by the integration circuit 88. The evaluation value calculation block 84 described with reference to FIG. 12 includes circuits corresponding to the absolute value circuit 87 and the integration circuit 88.

In the above description, the first smear detection method is used.
Although the method of the embodiment is applied, it is also possible to use the method of the second embodiment described in FIG. 4 for smear detection. In this case, since the smear data obtained from all the pixels in the AF area 70 is stored in the second memory 82, one-line smear data does not represent a smear component, and one-line smear data is used for all pixels in the AF area. The correction can be made in correspondence with 1.

Next, another embodiment will be described.

FIG. 16 is a block diagram of signal processing showing a second embodiment of specific means to which the first aspect of the smear detection method described with reference to FIG. 3 is applied. In the form shown in FIG.
A first operation block 91 that calculates an AF evaluation value from data (including a smear component) in the AF area 70 and a second operation block 92 that calculates an AF evaluation value from data (only the smear component) in the smear detection area. Have. Based on the data (data including smear) of the AF area 70 read out during the valid period, the first calculation block 91 calculates the AF evaluation value, while the 1 obtained by blank reading of the smear detection area.
From the smear data of the line, an AF evaluation value of the smear detection area is calculated in a second operation block 92.

Then, A obtained in the first operation block 91
A final evaluation value is obtained by subtracting a value obtained by multiplying the AF evaluation value obtained in the second operation block 92 by N (converting to N lines) from the F evaluation value.

As described above, the AF evaluation value of the AF area 70 and the AF evaluation value of the smear detection area are separately calculated, and the obtained AF evaluation value is finally subtracted to remove the influence of smear. A typical AF evaluation value is obtained.

The calculation accuracy can be further improved by averaging the information obtained from several lines that have been read in blank, not limited to the method of obtaining smear data from only one line that has been read in blank.

In the above description, the data in the AF area 70 is N
Since the smear data is one line in contrast to the line, the evaluation value obtained in the second operation block 92 is multiplied by N in order to match the number of pixels for evaluation value calculation (integration). When the number of pixels to be integrated by the first operation block 91 and the number of pixels to be integrated by the second operation block 92 are different, a predetermined value is added to at least one of the values integrated by the first operation block 91 and the second operation block 92. What is necessary is just to multiply by a coefficient.

Also in the second embodiment, as the smear detection method, the second mode described with reference to FIG. 4 can be used. In this case, calculation such as averaging of smear data and N-line conversion becomes unnecessary, and it is possible to subtract smear data from signal data (including smear components), thereby improving calculation accuracy.

As a further modification of the first and second embodiments, there is a mode in which the smear detection method can be switched. That is, as described with reference to FIG.
A reading method for acquiring smear data from an empty transfer portion other than 0 and a reading method for acquiring smear data from the same area as the AF area 70 as described with reference to FIG. Is also good.

FIG. 17 is a flowchart showing a control procedure of the electronic camera in which the smear detection method can be automatically switched. A program for automatically executing the control procedure shown in FIG.
M.

As shown in the figure, first, the first AF evaluation value is detected by AF photometry (step S11).
0). The AF evaluation value calculation at this time is performed according to a predetermined calculation method. In the first AF evaluation value calculation, any method can be applied, and a normal AF evaluation calculation that does not remove smear components may be used.

Following step S110, the level of the evaluation value detection accuracy is determined (step S112). The accuracy level is determined according to a predetermined method such as comparing the absolute value of the evaluation value obtained in the first AF evaluation value calculation process with a predetermined reference value.

If it is determined in step S112 that a predetermined accuracy level has been obtained (OK determination),
Proceeding to step S114, the first mode (referred to as “part 1”) of the smear detection method described with reference to FIG. 3 or the third mode (referred to as “part 3”) described with reference to FIGS. 5 to 10 is applied. The AF evaluation value is detected. On the other hand, step S1
In step 12, when it is determined that the predetermined accuracy level cannot be obtained (NO determination), the process proceeds to step S116,
The AF evaluation value is detected in the second mode (referred to as “part 2”) described with reference to FIG.

FIG. 18 is a flowchart showing another control procedure of the electronic camera in which the smear detection method can be automatically switched. In the example shown in the drawing, first, the smear detection method of “No. 1” or “No. 3” is applied to detect the AF evaluation value (step S210). Next, the level of the evaluation value detection accuracy is determined (step S212).

If it is determined in step S212 that a predetermined accuracy level has been obtained (OK determination),
Proceeding to step S214, the process ends. On the other hand,
If it is determined in step S212 that the predetermined accuracy level cannot be obtained (NO determination), step S2
Proceeding to 16, the AF evaluation value is detected by applying the method of "Part 2".

For example, in the case of photographing a dark scene, the evaluation value itself becomes a small value, so that the calculation accuracy can be improved by switching to the method of “Part 2”.

The determination of the light / dark state is not limited to the method of comparing the absolute values of the AF evaluation values calculated as described above.
The determination may be made based on the photometry result of (automatic exposure adjustment).

Next, a fourth embodiment of the present invention will be described. FIG. 19 is a timing chart showing the fourth embodiment. AF at each lens position while moving the lens
When an evaluation value is detected, a timing chart as shown in FIG. In the figure, the smear detection operation is "S",
The AF photometry operation is abbreviated as “AF”.

That is, the smear detection operation and the AF photometry detection operation are repeatedly performed in synchronization with the VD, and the smear detection operation is intermittently inserted while the AF photometry operation is repeated a plurality of times. In the example of FIG. 19, the AF photometry operation is repeated three times for one smear detection operation, but the insertion ratio is not limited to this.

The smear data obtained in the smear detection operation is applied to the AF photometry data obtained in the AF photometry operation to obtain an AF evaluation value from which the influence of smear has been removed. The lens is moved toward the in-focus position according to the AF evaluation value thus obtained. Similarly, the smear data acquired in the smear detection operation is represented by A
Applying the AF photometry data obtained in the F photometry operation to obtain an AF evaluation value from which the influence of smear has been removed, and moving the lens according to the obtained AF evaluation value.

The present invention is not limited to the above-described embodiment. The smear information obtained by the smear detection operation is calculated, and the calculation result of the smear information is calculated by the AF photometry operations
There is also an aspect in which a predetermined weight is applied to the photometric data and applied to obtain an AF evaluation value from which the influence of smear has been removed.

As shown in FIG. 19, by performing an operation for intermittently inserting a smear detection operation and using the smear data obtained by the smear detection operation to perform an operation for removing the influence of smear,
Accurate AF evaluation value detection becomes possible, and high-speed AF processing can be achieved.

[0086]

As described above, according to the present invention, A
Since the influence of smear was eliminated in the calculation of the F evaluation value,
Normal AF operation becomes possible, and it is possible to accurately focus on a main subject other than the high brightness light source.

In the present invention, an AF area for which an AF evaluation value is to be calculated is determined in a part of the image area, and the predetermined AF area is calculated.
By acquiring AF photometry data for the area and sweeping out unnecessary information other than the AF area, the processing speed can be increased.

Also, by providing a smear detection area outside the AF area and acquiring smear data from the smear detection area by an empty reading operation, and acquiring AF photometry data by a normal reading operation within the AF area,
The speed of the AF process can be increased.

When the AF evaluation value is detected at each lens position, by intermittently inserting the smear detection operation, it becomes possible to detect the AF evaluation value in which the influence of smear has been removed, thereby realizing a normal AF operation. As compared with the method in which the smear detection operation and the AF photometry operation are alternately repeated, the processing can be speeded up.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an interline CCD imaging device.

FIG. 2 is a block diagram of an electronic camera to which the AF device of the present invention is applied.

FIG. 3 is a timing chart showing a first embodiment of the smear detection method.

FIG. 4 is a timing chart showing a second embodiment of the smear detection method.

FIG. 5 is a timing chart showing a third aspect of the smear detection method.

FIG. 6 is a diagram showing a configuration example of a shooting screen;

FIG. 7 is a timing chart of AF processing applied to the CCD having the area setting shown in FIG. 6;

FIG. 8 is a diagram illustrating a configuration example of a shooting screen in which a smear detection area is provided outside an AF area.

FIG. 9 is a timing chart of AF processing applied to the CCD having the area setting shown in FIG. 8;

FIG. 10 is an enlarged view of the timing chart shown in FIG. 7;

FIG. 11 is a timing chart showing a first embodiment of an AF process to which the first mode of the smear detection method described with reference to FIG. 3 is applied;

FIG. 12 is a block diagram of means for realizing the AF processing shown in FIG. 11;

FIG. 13 is an explanatory diagram showing the contents of AF processing by means shown in FIG. 12;

FIG. 14 is a block diagram showing a basic configuration for calculating an evaluation value.

15 shows points E, F, and G in the block diagram shown in FIG. 14;
Figure showing an example of the signal waveform of

FIG. 16 is a block diagram showing a second embodiment of the AF processing to which the first aspect of the smear detection method described in FIG. 3 is applied;

FIG. 17 is a flowchart illustrating a control procedure of the electronic camera that enables the smear detection method to be automatically switched.

FIG. 18 is a flowchart showing another control procedure of the electronic camera in which the smear detection method can be automatically switched.

FIG. 19 is a timing chart in a case where AF evaluation value detection is performed at each lens position while the lens is moving.

FIG. 20 is an AF applied to a conventional digital camera.
Block diagram of processing system

FIG. 21 is an explanatory diagram used to explain a defect of an AF operation due to a smear phenomenon;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... CCD imaging device (solid-state image sensor), 12 ... Photo sensor (light receiving part), 14 ... Transfer gate, 16 ... Vertical transfer path, 20 ... Horizontal transfer path, 30 ... Electronic camera, 32 ...
Shooting lens, 34: CCD driver (drive circuit unit), 4
2 timing generator, 44 CPU (calculation means, AF evaluation value detection means, lens control means), 64 lens drive unit, 66 bandpass filter, 70 AF area, 81 first memory (first storage) Means), 82 ... second
Memory (second storage unit), 84: evaluation value calculation block (AF evaluation value detection unit), 91: first operation block (first AF evaluation value detection unit), 92: second operation block (second operation unit) AF evaluation value detection means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H04N 101: 00 G03B 3/00 A F term (Reference) 2H011 AA03 BA31 BB02 BB04 BB05 CA21 DA01 2H051 BA47 CB22 CE01 CE07 CE09 CE14 CE16 DA03 DA22 EB01 FA48 GB12 5C022 AA11 AB28 AB34 AB44 AC54 AC69 CA00 5C024 AX01 BX01 CX13 GY05 HX06 HX12 HX29 HX57

Claims (22)

[Claims] 1. A process for subtracting a smear component from output data of a solid-state image sensor, obtaining an AF evaluation value by a predetermined calculation method based on the data after the subtraction process, and a lens based on the obtained AF evaluation value. An automatic focus control method, wherein the camera is moved to a focus position. 2. An AF area for which an AF evaluation value is to be calculated in an effective pixel area of the solid-state imaging device is determined in advance, and an AF evaluation value is calculated based on data of the predetermined AF area. The autofocus control method according to claim 1, wherein: 3. An AF evaluation value is obtained by a predetermined calculation method based on the output data without performing a process of removing a smear component from output data of the solid-state imaging device.
Smear data containing only a smear component is obtained from the solid-state imaging device, an AF evaluation value is obtained by a predetermined calculation method based on the smear data, and the smear data is obtained from the AF evaluation value obtained from the output data. An autofocus control method, comprising performing a process of subtracting an AF evaluation value, and moving a lens to a focus position based on the AF evaluation value obtained by the subtraction process. 4. An AF area for which an AF evaluation value is to be calculated in an effective pixel area of the solid-state imaging device is determined in advance, and an AF evaluation value is calculated based on the output data in the predetermined AF area. 4. The method according to claim 3, wherein
3. The autofocus control method according to item 1. 5. A reading method for acquiring the smear data from an idle transfer portion outside the AF area and a reading method for acquiring the smear data from the same area as the AF area can be selectively switched. 5. The autofocus control method according to claim 2, wherein: 6. An auto-focus control method for detecting an AF evaluation value based on output data of a solid-state imaging device at each lens position while moving a lens, the method comprising: While repeating the operation of acquiring the AF photometry data including the image signal component and the smear component, the operation of intermittently inserting the operation of acquiring the smear data including only the smear component at a predetermined ratio is performed.
An autofocus control method comprising: obtaining an AF evaluation value from which influence of smear has been removed by using photometric data and smear data; and moving a lens toward a focus position based on the AF evaluation value. 7. An AF area for which an AF evaluation value is to be calculated in an effective pixel area of the solid-state imaging device is predetermined, and an AF evaluation value is calculated based on the AF photometric data obtained from the predetermined AF area. 7. The autofocus control method according to claim 6, wherein is calculated. 8. The autofocus control according to claim 2, wherein the smear data including only the smear component is represented by data acquired from an idle transfer portion outside the AF area. Method. 9. The autofocus control method according to claim 2, wherein the smear data including only the smear component is obtained from the same area as the AF area. 10. The auto-focus control method according to claim 2, wherein the smear data including only the smear component is obtained from a part of the idle transfer portion in the AF area. 11. A solid-state imaging device in which a plurality of light receiving units having a photoelectric conversion function are arranged in a plane and provided with a vertical transfer path and a horizontal transfer path for transferring signal charges generated in each light receiving unit. A driving circuit unit that drives the solid-state imaging device to output an image signal including a signal charge component and a smear component of a subject from the solid-state imaging device, and to output a smear signal including only the smear component; A first storage unit for storing AF photometry data including information on a signal charge component and a smear component of a subject acquired via an element; and a smear including information on only a smear component acquired via the solid-state imaging device. Second storage means for storing data; arithmetic means for performing processing for subtracting the smear data from the AF photometric data; and a result of the subtraction processing by the arithmetic means AF evaluation value detection means for obtaining an AF evaluation value by a predetermined calculation method based on the obtained data, and lens control means for moving a lens to a focus position based on the AF evaluation value obtained by the AF evaluation value detection means An autofocus device, comprising: 12. An AF area for which an AF evaluation value is to be calculated in an effective pixel area of the solid-state imaging device is predetermined, and an AF evaluation value is calculated based on data of the predetermined AF area. The autofocus device according to claim 11, wherein: 13. A solid-state imaging device in which a plurality of light receiving units having a photoelectric conversion function are arranged in a plane and provided with a vertical transfer path and a horizontal transfer path for transferring signal charges generated in each light receiving unit. A driving circuit unit that drives the solid-state imaging device to output an image signal including a signal charge component and a smear component of a subject from the solid-state imaging device, and to output a smear signal including only the smear component; First A for calculating an AF evaluation value by a predetermined calculation method based on AF photometry data including information on a signal charge component and a smear component of a subject acquired via an element.
F evaluation value detection means; second AF evaluation value detection means for obtaining an AF evaluation value by a predetermined calculation method based on smear data including only information on smear components obtained via the solid-state imaging device; Calculating means for subtracting the AF evaluation value of the smear data obtained by the second AF evaluation value detecting means from the AF evaluation value obtained by the first AF evaluating value detecting means; and subtraction processing by the calculating means And a lens control means for moving the lens to a focus position based on the AF evaluation value obtained in (1). 14. An AF area for which an AF evaluation value is to be calculated in an effective pixel area of the solid-state imaging device is predetermined, and an AF evaluation value is calculated based on the AF photometric data obtained from the predetermined AF area. The autofocus apparatus according to claim 13, wherein is calculated. 15. A switching means for selectively switching between a reading method for obtaining the smear data from an idle transfer portion outside the AF area and a reading method for obtaining the smear data from the same area as the AF area is added. The auto-focusing device according to claim 12, wherein the auto-focusing is performed. 16. The auto-focusing device according to claim 15, wherein said device has a discriminating means for discriminating the brightness of the object, and said discriminating means obtains a judgment that the brightness is lower than a predetermined reference level. In some cases, the switching unit is controlled to automatically switch to a reading method for acquiring the smear data from the same area as the AF area. 17. A solid-state imaging device in which a plurality of light receiving units having a photoelectric conversion function are arranged in a plane and provided with a vertical transfer path and a horizontal transfer path for transferring signal charges generated in each light receiving unit; A drive circuit unit that drives the solid-state imaging device so as to output an image signal including a signal charge component and a smear component of a subject from the solid-state imaging device and output a smear signal including only the smear component, and moves a lens. While repeating the operation of driving the solid-state imaging device at each lens position and acquiring AF photometry data including the image signal component and the smear component of the subject, at a predetermined rate, the smear data including only the smear component is removed. An AF in which the operation to acquire is intermittently inserted and the influence of smear is removed by using the obtained AF photometric data and smear data.
An AF evaluation value detection unit for obtaining an evaluation value; and a lens control unit for moving a lens toward a focus position based on the AF evaluation value obtained by the AF evaluation value detection unit. Focus device. 18. An AF area for which an AF evaluation value is to be calculated in an effective pixel area of the solid-state imaging device is predetermined, and an AF evaluation value is calculated based on the AF photometric data obtained from the predetermined AF area. The autofocus device according to claim 17, wherein is calculated. 19. The apparatus according to claim 12, wherein the smear data including only the smear component is represented by data acquired from an idle transfer portion outside the AF area.
19. The autofocus device according to 4 or 18. 20. The autofocus apparatus according to claim 12, wherein the smear data including only the smear component is obtained from the same area as the AF area. 21. The autofocus apparatus according to claim 12, wherein the smear data including only the smear component is acquired from a part of the idle transfer portion in the AF area. 22. The autofocus device according to claim 11, wherein the device has a bandpass filter that detects edges of a subject signal and a smear signal output from the solid-state imaging device, An autofocus apparatus, wherein the AF photometric data or the smear data is obtained from a signal output through the bandpass filter.