JP2000131602A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electronic camera for forming an image signal for focus detecting by controlling the starting and finishing of exposure in a 1st region at a prescribed timing, bringing forward the timing of the starting of exposure in a 2nd region from the timing of the starting of exposure in the 1st region and finishing the exposure in the 2nd region by closing a shutter to minimize the difference of phase of the image signal obtained by pupil dividing due to the movement of an object. SOLUTION: The difference of time to expose a solid state image pick-up element to the object light is set so that after finishing the exposure of the region initially set by the pupil dividing device 14, the exposure of next region is started direct after the pupil dividing device 14 sets the next region. The moving time of the object exposed by the solid state image pick-up element becomes a little time to drive the pupil dividing device 14 from one region to another region by setting to finish the exposure in the next region by closing the shutter. The focusing error of the moving object is minimized by producing the focus adjusting and controlling signal based on the detected result of the difference of phase based on both image signals by a little difference of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera which detects a focus position from a pupil-divided subject light beam and controls focusing of a photographing optical unit. It is an electronic camera that can be prevented.

[0002]

2. Description of the Related Art As a main automatic focusing method in an electronic camera, a pupil splitting device built in a photographic optical system is used. A phase difference detection method of converting and detecting a phase difference of an image signal of the divided and photographed subject light, which generates an image signal based on the photoelectrically converted electric charge, and adjusts and controls a focus lens position of an imaging optical system is provided. Has been adopted.

[0003] Various methods are used as a subject light dividing method of the pupil dividing device. The aperture / pupil dividing device described in Japanese Patent Application No. 10-213351 filed by the present applicant has been downsized. The best.

[0004] An aperture / pupil division apparatus described in Japanese Patent Application No. 10-212351 will be described with reference to FIG.

[0005] Two blades 4 on the left and right sides are arranged so as to cover a front open hole 41 in which a focus lens of a photographing optical system is disposed.
2, 43 are arranged. The blades 42 and 43 are rotatably supported by the rotating shafts 42a and 43a. These blades 42, 43 have cam holes 42b, 4 formed of elongated holes.
3b is formed, and a driving pin 44 is inserted through the cam holes 42b and 43b in common. The drive pin 44 is driven in a vertical direction in the figure by a drive actuator of a diaphragm / pupil division device (not shown), and a drive force is applied to the cam holes 42b and 43b by the drive pin 44. Transmitted to the blade 4
2, 43 rotate as described later. Further, the blades 42 and 43 have a configuration in which pupil openings 42c and 43c are formed at the edges away from the open hole 41.

An aperture / pupil splitting device having such a configuration is
The following rotation operation is performed.

FIG. 3A shows an open aperture state in which the blades 42 and 43 are opened from the open hole 41.
In this state, the drive pin 44 is located at the uppermost position in the drawing, and the blades 42 and 43 open left and right in the drawing to prevent the photographing light beam from passing through the opening hole 41. Has become.

[0008] From the open aperture state, the drive pin 44
Are moved downward in the figure, the left and right blades 42, 43
Moves in a direction to increase the overlapping portion of each other, and FIG.
As shown in (b), a part of the open hole 41 is shielded by the left and right blades 42 and 43, and a small aperture state is obtained in which the photographic light beam passing through the open hole 41 is stopped down.

When the driving pin 44 is further moved from the small aperture state in a direction in which the overlapping portion of the left and right blades 42, 43 is enlarged, as shown in FIG. The aperture is completely closed by the blades 42 and 43, and the aperture is in a closed state where the photographic light beam passing through the open hole 41 is shielded.

When the drive pin 44 is further moved downward from the aperture closed state, the left and right blades 42, 43
3 is moved in a direction to further increase the superimposed portion of FIG.
As shown in (d), only the pupil opening 42c of the left wing 42 enters the opening 41, and the left automatic focus opening (hereinafter, left A) through which the photographic light beam passes through the pupil opening 42c.
F opening).

From the left AF opening state, the driving pin 4
4 is moved to the lowermost position in the figure,
2 and 43 maximize the overlapping portion with each other, and as shown in FIG. 3E, the pupil opening 43c of the right wing 43 is
1 and the pupil opening 42c of the left wing 42
Is closed by the right blade 43, and enters a right automatic focus opening (hereinafter referred to as a right AF opening) in which a photographing light beam passes through the pupil opening 43c of the right blade 43.

That is, by changing the opening amount of the opening hole 41 in the small aperture state shown in FIG. 3B from the open aperture state shown in FIG. 3A to the aperture closed state shown in FIG. 3C, The amount of luminous flux incident on the solid-state imaging device (not shown) from the photographic optical system is adjusted. Further, a left image signal generated based on a photographing light beam incident on the solid-state imaging device in the left AF opening state in FIG. 3D and an incident on the solid-state imaging device in the right AF opening state in FIG. A phase difference from a right image signal generated based on the obtained photographing light beam is detected to adjust and control a focus lens position of the photographing optical system.

Next, using the aperture / pupil division device,
A method of generating a focus lens position adjustment control signal of the photographing optical system will be described with reference to FIG.

The VD in FIG. 4 refers to a vertical drive signal of a video signal, which is used to set a subject light exposure time, which is an image forming time of subject light incident on the solid-state image pickup device, or is photoelectrically converted by the solid-state image pickup device. It is used as a reference of control signals for various image signal generation circuits and the like for controlling read transfer timing of the transferred charges and generating image signals based on the charges read and transferred from the solid-state imaging device.

When a subject light photographed by the photographing optical system is imaged on the solid-state image pickup device at the time of photographing the object with an electronic camera, the accurately focused object light without a focus shift is imaged on the solid-state image pickup device. Need to be done. For this reason,
When the automatic focus adjustment mode provided in the electronic camera is selected and input, the pupil division device is driven based on the first rising edge of the VD signal VD1, and FIG.
In the left AF opening state shown in (d), the subject light that has passed through the pupil splitting device in the left AF opening state is incident on the solid-state imaging device (hereinafter, referred to as a CCD) and exposes the CCD for a predetermined time. .

On the basis of the next rising edge of the VD signal VD2, the pupil splitting device shown in FIG.
The subject light that has been driven into the F opening state and passed through the pupil splitting device in the right AF opening state is incident on the CCD, and
The CD is exposed for a predetermined time. Further, the VD signal VD2
The left image charge in the left AF opening state obtained by exposing and photoelectrically converting the CCD with reference to the rising edge of is read and transferred, output to the various image signal generation circuits, and temporarily stored in a predetermined circuit.

Next, based on the rising edge of the VD signal VD3, the pupil splitting device is driven to open the aperture stop shown in FIG. 3 (a) and to open the right AF aperture photoelectrically converted by the CCD. The right image charges photoelectrically converted in the above are read and transferred, and output to the various image signal generation circuits. The various image signal generation circuits generate image signals based on the charges of the left image and the right image read and transferred from the CCD, and detect a phase difference detected by a phase difference detection circuit based on the generated left and right image signals. Using a calculation formula stored in advance in a system controller formed by a microcomputer or the like based on a, a lens extension amount for adjusting the position of the focus lens is calculated, and the imaging optical system of the imaging optical system is calculated via a focus actuator. Automatic focusing control (hereinafter referred to as AF control) for performing position adjustment control of the focus lens is performed.

An electronic camera using focus detection based on such pupil division compares the phase shift amounts of respective images captured in different pupil regions and calculates the focus shift amount. The driving of the aperture / pupil division device sets a timing to a predetermined AF opening state with reference to a rising edge of one cycle of the VD signal, and the solid-state imaging device sets a falling edge of one cycle of the same VD signal. The exposure timing of the subject light is set based on the reference, and the readout of the charge photoelectrically converted by the solid-state imaging device is set based on the rising edge of one cycle of the next VD signal.

On the other hand, when photographing a moving subject,
If the interval between the left AF exposure and the right AF exposure is wide in the aperture / pupil splitting device, the subject itself moves between the shooting of the subject at the time of the left AF opening and the time of the right AF opening, and A shift occurs in the image signal generated by exposure.

Since the exposure timing is based on the rising edge of the VD signal, consecutively shot images always have an interval of time (t1) for one VD cycle.

Left and right AF generated by exposure using this solid-state image sensor
When phase comparison is performed using image signals and the phase difference is detected, the phase difference due to the movement of the subject is added to the phase difference due to the focus shift, making accurate focus detection impossible and losing the focus accuracy. Occurs.

[0022]

A conventional electronic camera detects a phase difference based on an image signal obtained from pupil-divided subject light, generates a focus adjustment control signal, and generates a focus lens position of a photographic lens system. Although the adjustment is being performed, the right and left A
Since a time difference occurs in the interval between F exposures, and the subject moves during this time difference, when the phase difference between the left and right AF image signals generated based on the charges converted by the solid-state imaging device is detected, the photographing is performed. Since the phase difference due to the movement of the subject is added to the phase difference of the focus shift due to the position of the focus lens of the optical system, the position of the focus lens is determined by a focus position control signal generated based on the added phase difference. There is a problem that an accurate in-focus position cannot be obtained even after performing the adjustment.

According to the present invention, there is provided an electronic camera for generating an appropriate focus detection image signal by minimizing a phase difference due to movement of an object in an image signal obtained by dividing the pupil when photographing a moving object. The purpose is to provide.

[0024]

SUMMARY OF THE INVENTION The present invention relates to a photographing optical means comprising a plurality of lenses including a focus lens, and a solid-state image pickup device for forming an image of subject light photographed by the photographing optical means and converting the light into an electric signal. Shutter means for mechanically blocking a photographic light beam incident on a solid-state imaging device from subject light photographed by the imaging optical means; and an image signal for generating an image signal based on the electric signal converted by the solid-state imaging device Generating means, pupil dividing means for dividing the photographing light beam of the photographing optical means into first and second regions in time series, and dividing by the pupil dividing means, wherein the solid-state imaging device and the image signal generating means Focus detection means for generating a focus position control signal based on the generated image signals of the different regions, and a focus position control signal generated by the focus detection means. Focus drive control means for performing position control, drive control of the pupil division means in time series to first and second areas, exposure drive control of the solid-state image sensor, and electric signal from the solid-state image sensor A reference signal generating means having a reference signal for performing readout control, wherein the reference signal generating means starts and ends exposure of the solid-state imaging device by the imaging luminous flux of the first area divided by the pupil dividing means. Control is performed at a predetermined timing, and the exposure start timing of the solid-state imaging device by the photographic light flux of the second area divided by the pupil division means is advanced earlier than the exposure start timing of the first area, and the second area is exposed. An electronic camera for terminating the exposure of the solid-state imaging device by closing the shutter means.

Further, the reference signal generating means controls the driving of the pupil dividing means to first and second areas, and further controls the pupil dividing means from the first and second areas or the second area of the pupil dividing means. An electronic camera that reads and controls the electric signals of the first and second regions converted by the solid-state imaging device after driving to the region is completed.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of an electronic camera according to the present invention.

Reference numeral 11 in the drawing denotes a photographing lens system for taking in light from a subject, and a zoom lens 12 for changing the size of the subject at least, a shutter 13, and a pupil splitting device 14 also serving as an aperture.
And a focus lens 15. In addition,
The aperture / pupil division device 14 performs the configuration and operation described with reference to FIG.

The subject light photographed by the photographing lens system 11 forms an image on the solid-state image pickup device 16. The solid-state imaging device (hereinafter, referred to as a CCD) 16 converts the formed subject light into electric charges. The charges converted by the CCD 16 are sequentially read and transferred to the imaging circuit 17 to generate an image signal. The image signal generated by the imaging circuit 17 is A / A
The image data is converted from an analog signal to a digital image signal by the D circuit 18, converted into digital data format image data by the image signal processing circuit 19, and temporarily stored in the memory 20.

The image data stored in the memory 20 is converted into an image reproduction signal by an image display circuit 21 based on an operation input described later, and the image of the subject light is reproduced and displayed on the image display section 22. The image display unit 22 uses a liquid crystal display element.

The image data temporarily stored in the memory 20 is compressed by a compression / expansion circuit 23 in response to an operation input, and is written and stored in a removable memory 25 via a memory interface (hereinafter, referred to as a memory I / F) 24. I do. The removable memory 25 is a memory medium formed as an IC card. The image data written and stored in the detachable memory 25 is read out via the memory I / F 24, the image data read out by the compression / expansion circuit 23 is expanded, and the image data is read out via the memory 20 and the image processing circuit 21. The display section 22 can also reproduce an image of the image data written and stored in the removable memory 25.

The digital image signal converted by the A / D circuit 18 is supplied to a phase automatic focus circuit (hereinafter referred to as a phase A
F circuit 26), a hill-climbing automatic focus circuit (hereinafter, hill-climbing AF circuit) 27, and a signal level determination circuit 28. The image data generated by the image processing circuit 19 is supplied to the phase AF circuit 26 and the hill-climbing AF circuit 27. The phase AF circuit 26
The phase difference of the image data is detected from the digital image signal generated based on the subject light pupil-divided by the aperture / pupil division device 14. The hill-climbing AF circuit 27 detects a high-frequency component of image data from a digital image signal generated based on subject light that has not been pupil-divided by the aperture / pupil division device 14. The signal level judgment circuit 28
The luminance value of the photographic subject is determined from the signal level of the digital image signal supplied from the / D circuit 18. Phase A
The outputs of the F circuit 26, the hill-climbing AF circuit 27, and the signal level determination circuit 28 are output from a system controller (hereinafter referred to as a syscon) 2 formed by a microcomputer.
9.

The system controller 29 is connected to the phase AF circuit 2
6 and the high-frequency component from the hill-climbing AF circuit 27 to perform focus drive control, which will be described later, and the luminance value from the signal level determination circuit 28 to control the drive of the aperture opening of the aperture and pupil division device 14. At the same time, the operation of the image processing circuit 19 is controlled. Further, the CC
D16 and a timing generation circuit (hereinafter, referred to as a TG circuit) 32 for controlling the operation of the imaging circuit 17 are also controlled.

An EEPROM 30 is added to the system controller 29, and stores various reference data necessary for operating or operating the electronic camera and processing procedures of the system controller 29 according to the operation.

Further, in the system controller 29, various photographing modes of the electronic camera, for example, selection of phase AF or hill-climbing AF at the time of focus adjustment, display of the image data temporarily stored in the memory 20 on the image display section 22, And writing and recording in the detachable memory 25, or selection of reproduction display of the image data stored in the detachable memory 25 on the image display unit 22, selection of the zoom lens magnification, selection of strobe operation, and release for shooting Each operation unit 31 for inputting various operations such as input is connected.

From the system controller 29, a zoom motor 33b is driven via a zoom circuit 33a for driving the zoom lens of the photographing lens system 11, and an actuator 34b is driven via a shutter circuit 34a for driving the shutter 13.
A driving circuit 3 for driving the aperture / pupil dividing device 14
A focus motor driving circuit 36a for driving the focus lens 15
And the focus motor 36b is connected to each other. The system controller 29 includes a strobe circuit 37a.
And strobe condenser 37b and strobe light emitting part 37
The series circuit c and the automatic focus auxiliary light (hereinafter, referred to as AF auxiliary light) 38 are connected.

In the electronic camera having such a configuration, a phase difference detection method using a pupil-divided photographed image is selectively input from each of the operation units 31 for adjusting the position of the focus lens of the photographing lens system 11, and the method involves movement. A focusing operation for photographing a subject will be described with reference to FIG.

In general, when performing focusing, a focusing mode is input in a state where a release switch (not shown), which is a part of each of the operation sections 31, is half-pressed.

When a focus mode is input from each of the operation units 31, the system controller 29 supplies a drive control signal to the drive circuit 35a with reference to the rising edge of VD1 of the VD signal. The actuator 35b is driven by the driving force from the above to bring the aperture / pupil division device 14 into the left AF opening state. on the other hand,
The system controller 29 controls the TG circuit 32 to generate a timing signal based on the VD signal and supplies the timing signal to the CCD 16 and the imaging circuit 17. The CCD 1
Reference numeral 6 denotes an exposure (hereinafter, referred to as a “subject light”) with the subject light incident in the left AF opening state of the aperture and pupil division device 14 at a predetermined timing after the drive of the pupil division device 14 is completed, based on the VD signal VD1. Exposure is terminated based on the falling edge of the VD signal VD1.

During the VD1 period of the VD signal, a control signal is supplied from the system controller 29 to make the shutter 13 of the photographing lens system 11 open. The solid-state imaging device 1
The exposure time of the left AF 6 is the time between the exposure start timing and the end timing supplied from the TG circuit 32.

Next, based on the VD signal VD2, the pupil splitting device 14 is driven to make the right AF opening state, and the CCD 16 is exposed by the subject light incident in the right AF opening state (hereinafter, referred to as the "hereafter"). Right AF exposure). At this time, the TG circuit 32 is connected to the pupil division device 14.
After the driving of the solid-state imaging device 1 to the right AF opening state is completed,
6 is started, and a timing signal for terminating the exposure based on the falling edge of the VD signal VD2 is supplied. During the period of the VD signal VD2, the shutter 13 is moved from the system controller 29 to the solid-state imaging device 16.
After a lapse of a predetermined time from the start of exposure, a control signal for closing is supplied. As a result, the exposure time in the right AF opening state in the solid-state imaging device 16 is set to the right A
This is the time between the start of exposure after the end of the F-opening drive and the shutter 13 blocking the subject light passing through the right AF opening.

At this time, the closing timing of the shutter 13 is set so that the left AF exposure time of the solid-state imaging device 16 and the right AF exposure time are substantially equal.

That is, the exposure of the solid-state imaging device 16 at the time of opening the left AF in the first photographing area divided by the pupil division device 14 is performed by driving the pupil division device 14 based on the rising edge of the VD signal. Exposure is started after a lapse of a predetermined time, and exposure is terminated based on the fall of the VD signal.

On the other hand, in the exposure of the solid-state imaging device 16 at the time of opening the right AF in the next photographing area, the pupil division device 14 is driven on the basis of the rise of the VD signal, and after the driving is completed, the exposure is started immediately. Exposure is terminated on the basis of the falling edge of the signal. After the driving of the pupil division device 14 in the right AF opening state is completed, subject light incident on the solid-state imaging device 16 is blocked by the shutter 13 after a predetermined time. That is, the difference between the end timing of the left AF exposure and the start timing of the right AF exposure is determined by the left A
Only the driving time from the F opening to the right AF opening state can be obtained.

As described above, the charge generated by the exposure by the solid-state imaging device 16 transfers and outputs the charge of the left AF exposure during the VD2 of the VD signal, and the charge of the right AF exposure during the VD signal VD3. The charge is transferred and output, and is converted into a digital image signal by the imaging circuit 17 and the A / D circuit 18. The phase difference is detected by the phase AF circuit 26. Based on the phase difference, the focus lens 15 is Is calculated and the focus motor 36b is driven and controlled via the focus motor drive circuit 36a to perform focusing.

As described above, a subject with motion is captured by subject light for each pupil-divided area, and a focus adjustment control signal is generated based on the phase difference between image signals generated from the captured different areas of subject light. In the electronic camera for adjusting the optimal focus by using the pupil division device, after the exposure of the region initially set by the pupil division device with the time difference for exposing the subject light to the solid-state imaging device is completed, the pupil division device starts the exposure of the next region. Is set immediately after setting the next area, and the end of the exposure of the next area is set by closing the shutter, so that the movement time of the subject exposed by the solid-state imaging device is changed from one area of the pupil division device. It takes a short time to drive to the other area. By generating a focus adjustment control signal based on the result of phase difference detection based on both image signals due to this slight time difference,
It is possible to minimize the focusing error of a moving subject. Further, by setting the start of the exposure of the other region of the solid-state imaging device after the end of the driving of the pupil dividing device 14, an image is formed on the solid-state imaging device due to the vibration generated when the actuator 35b for driving the pupil dividing device is driven. The blurring of the subject can be eliminated.

[0046]

According to the electronic camera of the present invention, in focusing at the time of photographing a moving subject, a photographing timing error between different pupil-divided regions is driven from one region of the pupil dividing device to the other region. By setting it for time, it becomes possible to make the focusing error a minimum error that can be almost ignored.
In addition, there is an effect that blurring of subject light to be imaged on the solid-state imaging device due to driving vibration at the time of driving the pupil division device can be eliminated.

[Brief description of the drawings]

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

FIG. 2 is a timing chart illustrating the operation of the present invention.

FIG. 3 is a plan view for explaining the operation of the pupil division device according to the present invention.

FIG. 4 is a timing chart for explaining a problem of a phase difference detection AF used in a conventional pupil division device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Photographing lens system 12 ... Zoom lens 13 ... Shutter 14 ... Aperture / pupil division device 15 ... Focus lens 16 ... Solid-state imaging device 17 ... Imaging circuit 18 ... Analog / Digital conversion circuit 19 ... Image processing circuit 20 ... Memory 21 ... Image Display circuit 22 ... Image display device 23 ... Compression / expansion circuit 24 ... Memory interface 25 ... Removable memory 26 ... Phase difference automatic focus circuit 27 ... Chill climbing automatic focus circuit 28 ... Signal level judgment circuit 29 ... System controller 30 ... EEPROM 31 ... Each operation Unit 32: Timing generator circuit 33a: Zoom circuit 33b: Zoom motor 34a: Shutter circuit 34b: Actuator 35a: Drive circuit 35b: Actuator 36a: Focus motor drive circuit 36b: Focus Motor 37a ... strobe circuit 37b ... flash capacitor 37c ... flash projector 38 ... autofocus auxiliary light

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 3/00 A

Claims (2)

[Claims] A photographing optical unit including a plurality of lenses including a focus lens; a solid-state imaging device for forming an image of subject light photographed by the photographing optical unit and converting the light into an electric signal; Shutter means for mechanically blocking a photographing light beam from subject light incident on the solid-state image sensor; image signal generating means for generating an image signal based on an electric signal converted by the solid-state image sensor; and the photographing optical means Pupil dividing means for dividing the photographing light beam into first and second areas in a time-series manner; dividing the pupil dividing means by the pupil dividing means to generate image signals of different areas generated by the solid-state imaging device and the image signal generating means. Based on
Focus detection means for generating a focus position control signal; focus drive control means for controlling the position of a focus lens of the photographing optical means by the focus position control signal generated by the focus detection means; Generating a reference signal having a reference signal for performing time-series driving control of the dividing means to the first and second regions, exposure driving control of the solid-state imaging device, and read-out control of an electric signal from the solid-state imaging device Means for controlling the start and end of exposure of the solid-state image pickup device by the reference signal generating means with the imaging luminous flux of the first area divided by the pupil dividing means at a predetermined timing, the pupil dividing means Exposure start timing of the solid-state imaging device with the imaging light flux of the second area divided by the above is advanced earlier than the exposure start timing of the first area, and the solid-state imaging of the second area is performed. An electronic camera, characterized in that to terminate the exposure of the device by closing of said shutter means. 2. The reference signal generating means controls the drive of the pupil dividing means to first and second areas, and further controls the pupil dividing means from the first and second areas or the second area. 2. The electronic camera according to claim 1, wherein after completion of the driving to the area, the electric signal converted by the solid-state imaging device for each of the first and second areas is read and controlled.