JP2000295535A - Solid-state image pickup device and photographing control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact solid-state image pickup device that obtains a picture with high quality in consecutive shots in response to a speed requirement at full pixel reading and power consumption of which can be reduced and to obtain an exposure control method. SOLUTION: An operation section 12 of a digital camera 10 sets a photographing condition and selects photographing timing and an exposure adjustment section 20 decides a luminous quantity for exposure supplied to a CCD 22 whose pixels are all read according to the setting and the selection. The exposure adjustment section 20 uses an aperture adjustment mechanism 200 that sets a prescribed aperture, an electronic shutter function section 204 and a mechanical shutter mechanism 202 that decide the exposure time. In the case of two-consecutive shots, the mechanical shutter mechanism 202 is open for the 1st exposure and a shutter period of the electronic shutter function section 204 is set as the exposure time, the electronic shutter function section 204 is open in its own timing for the next exposure, and the mechanical shutter mechanism 202 completes photographing so as to completely shut light at the end of the 2nd photographing thereby preventing occurrence of smear that may be, otherwise, produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a solid-state imaging device and an imaging control method. For example, the present invention is applied to a digital camera or the like which reads out all pixels when imaging an object scene, and shoots two consecutive frames. It is suitable for use in

[0002]

2. Description of the Related Art Conventionally, a solid-state imaging device using a mechanical shutter has been proposed for photographing a still image with an interline scanning imaging device. The interline scanning includes so-called 2: 1 scanning for generating an image signal of one frame from two field signals, for example. One specific proposal is a solid-state imaging device disclosed in Japanese Patent Publication No. 3-22756. Until now, even if a picture element for one frame is provided in advance, a time-shifted video signal, that is, a field signal is obtained, so that a flicker phenomenon has occurred in a still image of one frame, resulting in deterioration of image quality. In this device, the proposal is to control the exposure time by controlling the driving of an optical shutter, to simultaneously capture images for each field, and to control the reading of signal charges captured in a field-sequential manner.

Further, scanning different from interlaced scanning,
That is, there is an imaging device for progressive (sequential) scanning. In this imaging device, all-pixel reading is used. An imaging device that performs this reading does not require a mechanical shutter that determines the exposure time. There has never been an example in which a mechanical shutter is mounted on an imaging device that performs this scanning. The mechanical shutter in this case does not indicate a shutter for light shielding.

[0004]

By the way, it has been desired to minimize the influence of smear, which is a false signal appearing above and below, in an imaging device for reading out all pixels. To realize this, high-speed reading is required. In order to perform high-speed reading, the applied voltage of the imaging device must be higher than the applied voltage in normal reading.
As a result, high-speed reading of the imaging device increases power consumption. Therefore, an increase in the speed of the imaging device leads to an increase in the capacity of the battery. This increases the size of the battery, which hinders, for example, the miniaturization of a digital camera equipped with this imaging device.

[0005] In a camera, generally, for example, 2
In some cases, shooting of a subject is corrected by continuously shooting frames and selecting and using an image that has been well shot. When performing this continuous shooting with a digital camera,
The reading of the signal must be completed within a predetermined time accompanying the high-speed continuous shooting. Considering this time, the number of pixels from which signal charges are read is limited. That is, the number of pixels is
For example, signal charges are read out with the pixel size set to 640 × 480 pixels or less. However, the image quality of the obtained image is low in quality since the image is composed of a smaller number of pixels than in normal reading. On the other hand, in order to obtain a high-quality image even in continuous shooting, an imaging device having a large number of pixels must be used. Since it takes time to read out the signal charges, the photographing interval in continuous shooting becomes long.

The present invention solves the above-mentioned drawbacks of the prior art, and achieves a high-quality image by performing continuous shooting in accordance with a required speed in all-pixel reading, and at the same time, can reduce the power consumption at that time. It is an object to provide a solid-state imaging device and a shooting control method.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention converges incident light from a supplied scene with an optical system, and condenses the light condensed by the optical system into an image pickup means. Operating means for operating the setting of imaging conditions of the apparatus and the selection of imaging timing in a solid-state imaging device which performs photoelectric conversion at the same time and performs imaging by reading out all pixels of signal charges obtained by the photoelectric conversion; and Capturing the exposure light quantity of the incident light supplied to the imaging means in accordance with the imaging conditions and timing set in the above with the predetermined aperture value set when the exposure light quantity is combined with the aperture value representing the transmission cross-sectional area of the incident light First opening / closing setting means for electrically setting the start / stop setting as the incident light capturing time and light amount adjusting means for adjusting the second opening / closing means for mechanically setting the incident light capturing time. A period for capturing the incident light supplied to the imaging means via the light amount adjusting means, and a drive signal for reading out the signal charges obtained by photoelectric conversion of the incident light, and adjusting the light amount adjusting means to the aperture value. Drive signal generation means for generating a drive signal to be performed, signal processing means for performing signal processing on signal charges from the imaging means, and control means for controlling the drive signal generation means and the signal processing means according to information from the operation means. And the first opening / closing setting means includes:
In the case where two consecutive shootings are performed, the first exposure time is set in the adjustment of the exposure light amount, and the second opening / closing setting unit determines the end timing of the second shooting.

Here, the first setting means is an electronic shutter for electrically starting / stopping the capture of the incident light, and the second setting means is a second shutter.
The opening / closing setting means is preferably a mechanical shutter mechanism that keeps the incident light incident state for at least a longer time than the incident light capturing time according to the aperture value.

It is desirable that the light amount adjusting means includes a light emitting means for emitting light by compensating for a light amount difference generated between the light amount from the object field and the light amount of the photographing condition. By adjusting the third setting means in consideration of the light amount adjusting means, it is possible to avoid a phenomenon in which the subject is crushed blackish particularly in a dark scene or a backlight scene.

The operation means includes a first operation selection means for supplying a photographing timing of the scene, and a second operation selection means for setting photographing conditions of the scene and selecting a photographed image. Is preferred.

The signal processing means includes an analog processing means for performing an analog signal processing on the supplied signal charge, a digital conversion means for converting an output from the analog processing means into a digital signal, and a digital signal from the digital conversion means. Digital processing means for performing digital signal processing on the image data; time adjusting means for storing and outputting two image signals supplied from the digital processing means;
A signal selecting unit that analyzes a frequency component of each image signal supplied from the time adjusting unit and selects an imaging signal containing more high frequency components among the frequency-analyzed image signals. It is desirable. This makes it possible to exclude, from the digitized image signal, an image including a camera shake at the time of shooting or a shake due to movement of the subject itself.

In the solid-state imaging device according to the present invention, the photographing conditions are set and the photographing timing is selected by the operation means.
The amount of exposure light supplied to the imaging means is determined according to these. This exposure light amount is performed by light amount adjustment means. In the light amount adjusting means, a predetermined aperture value which has been set and an incident light capturing time, which is another parameter for the predetermined aperture value, are first open / close setting means and a second which mechanically sets the incident light capturing time. Is adjusted by the operation of the open / close setting means. That is, for example, when taking two consecutive shots,
In the first exposure, the second opening / closing setting means is opened, and the opening / closing period of the first opening / closing setting means is set as the exposure time. In the second exposure, the second opening / closing setting means is opened at the timing of the first opening / closing setting means. Is closed (imaging is completed) by the opening / closing setting means. As a result, the second shooting is completely shielded at the end of the shooting, so that the influence (smearing) of the light leaking when the electronic shutter is in the closed state at the time of reading the signal is eliminated as compared with the case without the mechanical shutter. Therefore, in the case of taking two consecutive shots, it is possible to prevent smear, which is a problem in reading all pixels, so that a large shooting interval which has been set for the countermeasure is unnecessary. With this operation, it is also possible for the signal processing means to select only the image desired by the user without waste.

According to the present invention, there is provided an image pickup means which collects incident light from a field to be supplied by an optical system, and supplies the amount of the incident light by adjusting the amount of exposure light in accordance with photographing conditions. In the photographing control method in which the incident light is photoelectrically converted into signal charges which are electric signals, and the signal charges are read out by reading all the pixels, the photographing conditions are set when photographing is continuously performed a plurality of times. A condition setting step to be performed, an aperture drive signal for setting a predetermined value as an aperture value representing the size of the transmission cross-sectional area of the incident light according to the imaging conditions set in the condition setting step, and the incident light represented by start / stop of capture A first signal generation step of generating a first drive signal contributing to the electrical adjustment of the first exposure light amount and a second drive signal contributing to the mechanical adjustment, respectively, by setting the capture time of Set in the setting process Diaphragm drive signal to the next predetermined value corresponding to the shadow condition, first by setting the acquisition time of the incident light 2
And a second signal generation step of generating a fourth drive signal that contributes to the electrical adjustment of the exposure light amount and a fourth drive signal that contributes to the mechanical adjustment. A timing determining step of generating a timing signal indicating the shooting timing of the object scene under the shooting conditions, and a first drive signal among the aperture drive signal and the first and second drive signals generated in the timing determining step. A first imaging step of performing a first imaging in accordance with a timing of a drive signal, and after the first imaging is completed, a first signal for reading out signal charges obtained by the imaging to a vertical transfer path of a prepared imaging unit. A moving step, after this first signal moving step, a signal removing step of removing excess signal charges in preparation for the next exposure, and after this signal removing step, an aperture drive signal is supplied as a second photographing step And supplied Photographing is started at the timing of the start of the photographing of the third drive signal, and the second photographing is performed to end the photographing at the timing of the end of the photographing of the fourth drive signal. A first signal readout step for reading out from the imaging means, and a second signal movement step for reading out signal charges obtained by the second imaging to the vertical transfer path of the imaging means after the first signal readout step is completed. After the second signal transfer step, the signal charges transferred in the second signal transfer step are read out from the imaging means, and the signal charges obtained in the first and second signal readout steps are added to the signal charges. And a signal processing step of performing signal processing. In the signal processing step, one or both of the images obtained in the first and second signal reading steps are selected.

Here, the timing signal may be generated using a vertical synchronization signal after performing a shooting operation as a timing reference.

The fourth drive signal is in a state where incident light can be made incident at the same time as the start of taking in the incident light set by the second drive signal, and it is desirable that this incident state be continued until the end of photographing. .

The signal processing step includes an analog step of performing analog signal processing on the supplied signal charges, a conversion step of converting an output signal after the analog step into a digital signal, and a digital signal obtained by the conversion step. , A digital adjustment process for temporarily holding and outputting an output signal of the first and / or second imaging process after the digital process, and a timing adjustment process. It is preferable that the method further includes a step of performing frequency analysis on the imaging signal and selecting an imaging signal containing more high frequency components based on the obtained analysis result. This allows
It is possible to automatically select an imaging signal that is a preferable image from the two imaging signals.

In the signal selecting step, it is preferable to use a frequency analysis function when performing compression processing on the selected image pickup signal.

The signal processing step includes, after the timing adjustment step, a display step of displaying two imaging signals output to the prepared display means, and an image selection step of selecting one or both of the images displayed in the display step. It is preferable that a process, a compression process of performing a compression process on an image signal of the image selected in the image selection process, and a recording process of recording the compressed image signal after the compression process on a recording medium are sequentially performed.

Preferably, the signal processing step includes an image synthesizing step of synthesizing the two output imaging signals after the timing adjusting step. Thus, when two images are captured with different exposure light amounts, the dynamic range of the combined image can be expanded.

[0020] The image synthesizing step may include an averaging step of averaging two obtained image pickup signals when photographing with the same exposure light amount is performed in the first and second signal generation steps. desirable. It is possible to improve the S / N of the imaging signal obtained by this combination.

In the averaging step performed in the image synthesizing step, an image difference step for obtaining a difference between the obtained two image pickup signals, and it is determined whether a difference value obtained in the image difference step is smaller than a predetermined value. And performing an averaging operation only when the result of the determining step is smaller than a predetermined value. When the difference value is larger than a predetermined value, the two imaging signals are supplied to a signal selecting step or an image selecting step. It is preferable to select any one of the imaging signals.

In the first signal generation step and the second signal generation step, one of the first signal generation step and the second signal generation step is set to a normal appropriate exposure light amount, and the other exposure light amount is set. Is preferably set to an exposure light amount having a difference from a normal appropriate exposure light amount. In this case, since the exposure of each image pickup signal is different, for example, bracketing can be easily performed. As a specific example, the difference from the normal appropriate exposure light amount is a first value indicating the normal appropriate exposure.
When the second aperture value is set to 1/2 or 1/3 of the interval between the aperture value of the first aperture value and each of the adjacent aperture values before and after the first aperture value, the second aperture value is set to the second aperture value. It is desirable to set by the first and second drive signals or the third and fourth drive signals.

In the first and second signal reading steps, it is preferable that each signal reading period is set to be read over a plurality of vertical synchronization periods. Thus, the processes of imaging and signal reading can be handled separately. In other words, the signal charges are read at a low speed while the imaging is performed at a high speed, and the request can be satisfied even when the applied voltage at the time of reading the signal charges is suppressed.

According to the photographing control method of the present invention, the photographing conditions are set, and the first exposure light amount and the second exposure light amount are adjusted to a predetermined value according to the set photographing conditions and the time for capturing the incident light. The drive signals are set in advance and the first
Is performed at the timing of the first drive signal, and after this exposure is completed, the obtained signal charges are read out to the vertical transfer path of the imaging means, and excess signal charges are removed in preparation for the next exposure.
Then, the second imaging is performed by starting imaging with the third drive signal and ending imaging with the fourth drive signal, and reading out the obtained signal charges from the imaging means. With this processing, in particular, in the second imaging, the timing of mechanically ending the imaging with the fourth drive signal is supplied, and the physical light is also blocked. Thereby, when reading out the signal charges obtained by the second photographing to the vertical transfer path of the imaging means, it is possible to prevent light leakage and to suppress the influence of smear which is likely to occur in reading out all pixels. In addition, this makes it possible to minimize the first and second photographing intervals, and to obtain an image with little time lag. Furthermore, the obtained signal charges are each subjected to signal processing, and only one or both of the obtained images are selected to record only valid images, or a higher image quality than an image obtained under a single shooting condition. Is obtained.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a solid-state imaging device and a photographing control method according to the present invention.

A digital camera 10 to which the solid-state imaging device of the present invention is applied will be described with reference to FIGS. The digital camera 10 has an operation unit 12, an optical lens 1
4, system control unit 16, drive signal generation unit 18, exposure adjustment unit 2
0, a CCD (Charge Coupled Device: hereinafter, referred to as a CCD) 22, a signal processing unit 24, a display 26, and a recording medium 28.

The operation unit 12 is provided with a shutter switch 12a and a key switch 12b. This operation unit 12
Is provided on the surface of the housing of the digital camera 10.
The shutter switch 12a is a switch for supplying timing to a plurality of stages. Shutter switch 12 as function
a has a function of pressing the switch to the first stage (so-called half-pressed position) to firstly make incident light from the object field that has passed through the optical lens 14 incident on the switch with a light beam corresponding to a predetermined aperture value; Press the switch further deeply to the second stage of the switch (so-called
There is a function to perform imaging at the timing when the button is pressed to the fully pressed position). The key switch 12b is a switch having a function of selecting a plurality of processing modes in the digital camera 10 and a function of selecting a cross key (not shown). The key switch 12b selects a processing mode at a predetermined instruction mark position from among a plurality of processing modes. In the digital camera 10, when various settings in the selected processing mode are performed, selection items, setting items, a cursor, and the like are displayed on the liquid crystal display so that selection and setting can be easily performed even with the small digital camera 10, For example, selection and setting are performed from the displayed items by using the cross key to move the cursor. Shutter switch 12a of operation unit 12
And key switch 12b are used to transmit information about timing signals and shooting conditions by pressing and selecting operations to the system bus.
It is supplied to the system controller 16 via 10A. In addition,
The operation unit 12 also includes a power switch and the like (not shown).

The optical lens 14 is an optical component that focuses an incident light beam from an object scene on a position on an imaging surface. The optical lens 14 has a position control of the lens 14 in accordance with the drive signal from the drive signal generator 18, that is, an AF (Automatic Focus).
Control is provided.

The system control unit 16 includes, for example, a CPU
(Central Processing Unit) is used. The system control unit 16 controls the drive signal generation unit 18, the signal processing unit 24, the display 26, and the recording medium 28 via the system bus 10A, as will be individually described later.

Although not shown, the drive signal generator 18 includes a clock generator and a timing signal generator. The drive signal generator 18 is supplied with a control signal corresponding to the photographing conditions obtained from the system controller 16 via the system bus 10A. The drive signal generator 18 controls the optical lens 14 based on various signals from the clock generator and the timing signal generator and the supplied control signal.
Drive signals are generated in the exposure adjustment unit 20 and the CCD 22, respectively. The output signal from the drive signal generation unit 18 to the exposure adjustment unit 20 is represented by one signal line as shown in FIG. 1, but a signal for driving the optical lens 14 and the exposure adjustment unit 20 is supplied to each. ing.

The exposure adjusting section 20 includes a light amount adjusting section 20a and a light emitting section 20b. The light amount adjustment unit 20a is arranged between the optical lens 14 and the imaging surface of the CCD 22. The light amount adjustment unit 20a has an aperture adjustment mechanism as an actual configuration.
200 and a mechanical shutter mechanism 202 are provided (see FIG. 2). In FIG. 1, the CCD 22 is not included in the light amount adjustment unit 20a for convenience, but the CCD 22 has an electronic shutter function as described later. For this reason,
The light amount adjustment unit 20a shown in FIG. 2 also shows an electronic shutter function unit 204 (first open / close setting unit) including the CCD 22. Here, the exposure light amount is an amount determined using the incident light beam and the time for irradiating the light beam as parameters. In accordance with these parameters, the aperture adjustment mechanism 200 adjusts the incident light flux, that is, the cross-sectional area of the incident light, and the mechanical shutter mechanism 202 operates with a mechanical shutter (not shown).
Adjust the irradiation time, which is represented by the open time. The irradiation time can also be adjusted by the opening and closing time of the electronic shutter function unit 204 of the CCD 22. Aperture adjustment mechanism 200
The mechanical shutter mechanism 202 used heretofore is used. When the aperture is fixed, the shutter and the aperture may be shared. Further, the light emitting section 20b is a strobe that emits light when the subject in the field of view has a low illuminance at which an appropriate amount of exposure light cannot be obtained due to the above-described parameter relationship during exposure. The light emitting section 20b also emits light according to the drive signal supplied from the drive signal generation section 18. Since the drive signal is generated under the control of the system control unit 16, the drive signal is supplied from the drive signal generation unit 18 to the light emitting unit 20b in synchronization with the timing at which the imaging operation of the shutter switch 12a of the operation unit 12 is performed. Is done.

The reason why the mechanical shutter mechanism 202 is provided in the digital camera 10 will be briefly described. When all pixels are read out by the digital camera 10 at high resolution, it is difficult to perform two consecutive frames. For example, when continuously photographing an image sensor with an effective pixel count of 1280 x 960 pixels with an exposure time of 1/60 second, approximately 15
00 × 1200 pixels must be sent in 1/60 second. Therefore, the transfer time per pixel is (1/60) / (1500 × 1200)
≒ 9nsec. When A / D converting the supplied signal,
The clock frequency used is an unrealistic value of about 108 MHz. Digital camera 10 that reads all pixels
By providing the mechanical shutter mechanism 202, the on / off of exposure other than the electronic shutter can be adjusted, and the signal reading time can be increased by 1 VD or more. Details will be described later.

The mechanical shutter mechanism 20
2 and the electronic shutter function unit 204, the names of the mechanisms and functions and reference numerals are omitted, and the terms mechanical shutter and electronic shutter are simply used.

The CCD 22 is a charge-coupled device (so-called pixel)
Are arranged such that an imaging surface is formed by a two-dimensional plane. Although not shown, the CCD 22 is provided with a color separation filter on the incident light side of the CCD 22 in parallel with the imaging surface. The color filters of the color separation filters are arranged corresponding to the pixels. As the color separation filter, for example, a primary color filter is used. The CCD 22 is provided with a vertical transfer path adjacent to the pixel for transferring signal charges in the vertical direction and a horizontal transfer path for transferring signal charges from the vertical transfer path in the horizontal direction.
Further, a transfer gate for transferring signal charges from the pixel side to the vertical transfer path in accordance with the supplied drive signal is provided between each pixel and the vertical transfer path. Such an image sensor is not limited to a CCD, but may be, for example, a MOS (Metal Oxide Semiconductor).
An nductor (metal oxide semiconductor) type image sensor may be used. However, the point different from the CCD is that the strobe light emission period in this case is during the vertical flyback period. To the CCD 22, a drive signal for notifying the opening / closing timing of an electronic shutter, which is an electric shutter operation, is supplied from the drive signal generation unit 18.
The CCD 22 has an electronic shutter function unit 204, and performs an electronic shutter function according to a supplied drive signal. Thus, the CCD 22 itself can be regarded as an electronic shutter. As will be described later, a drive signal is supplied to the CCD 22 to read out signal charges obtained by photoelectrically converting incident light as signals from a transfer gate, a vertical transfer path, and a horizontal transfer path. The CCD 22 outputs a signal obtained by current / voltage conversion of a signal charge obtained via an amplifier to the signal processing unit 24, for example.

The signal processing unit 24 includes an analog processing unit 24a,
A / D converter 24b, digital processor 24c, image processor 24
d and a compression processing unit 24e. Although not shown, the analog processing section 24a includes a Correlation Double Sampling (hereinafter, referred to as CDS). Further, the analog processing section 24a may be provided with a gamma correction section. It is known that the CDS exerts an effect on the obtained signal, particularly in reducing thermal noise, and improves the S / N ratio.

The A / D converter 24b has an analog processor 24a
A / D that converts the signal supplied from
A converter is provided. The digital processing unit 24c includes:
Although not shown, a high-frequency signal processing unit and an interpolation processing unit are provided. The high frequency signal processing unit, from the signals supplied, for example, with extending the band higher than the normal frequency band having the luminance signal in the vertical direction / horizontal direction in correspondence with the pixels by Y _H · Y _L method, vertical Processing is performed so that the frequency ranges in the direction / horizontal direction do not overlap, thereby improving the quality of the signal. When a single-chip color separation filter is used, the interpolation processing unit performs an interpolation process for generating the other two colors of the color filter arranged at that position. When performing this interpolation processing, the three primary colors RGB are used by using the obtained high-range luminance signal.
Is calculated. As a result, plane data of three primary colors RGB is obtained for each pixel in the effective screen area in the CCD 22.

The image processing section 24d includes a digital processing section 24.
In order to store the three primary color RGB data from c, for example, a frame memory for storing image data corresponding to two image pickup signals is used, and the supplied data is subjected to image processing. As this frame memory, a nonvolatile memory may be used. The image processing unit 24d also includes a calculation unit (not shown) so as to be used when performing image processing. In this embodiment, the image processing unit 24d outputs the image data once stored in the buffer memory to the compression processing unit 24e and the display 26 in frame units.

The compression processing unit 24e has a JPEG (Joint Joint) which is an international standard for encoding the supplied image data (still image).
A configuration of a compression process based on the Photographic Experts Group is provided. The compression processing unit generally includes a block conversion unit, a DCT (Discrete Cosine Transform: abbreviation for discrete cosine transform) unit, a quantization unit, and a variable length coding unit. The block converter divides the supplied image data into, for example, 8 × 8 pixels as one block. The DCT unit is an operation unit that calculates a DCT coefficient so that signal power is concentrated by conversion using an orthogonal function. The quantization unit assigns a level number by dividing the obtained quantization representative value for the DCT coefficient by the quantization step. The variable length coding unit has a function of performing zigzag scanning of the level numbers in the order from the low frequency components to the high frequency components, and has a continuous number of level numbers (so-called zero run length) and subsequent zeros. There is a function of grouping level numbers (non-zero numbers) and assigning one code to this group. The signal processing unit 24 is controlled by the control signal supplied from the system control unit 16 via the system bus 10A to the configuration of each unit described above.

The display 26 has a liquid crystal monitor for displaying image data (RGB) in frame units supplied from the image processing section 24d. The display 26 may have a function of displaying one image continuously at a predetermined time interval. Further, a function of displaying the obtained two images in the same frame may be provided. These functions are performed by a monitor control unit (not shown). On the display 26, an item for selecting one or both of the captured images is displayed together with a cursor. When one of the images is selected, an item indicating which image is selected is also displayed. Such monitor display is performed according to data and control signals supplied from the system control unit 16 via the system bus 10A. The display 26 performs image display and monitor display under the control of the monitor control unit.

The recording medium 28 has an EEROM (Electrically E
(rasable PROM) or a memory card is used. The memory card records the compressed image data on a card having a thickness of several millimeters, for example.

Next, each operation associated with the photographing control of the digital camera 10 will be described with reference to flowcharts. The digital camera 10 is activated by turning on a power switch and performs an initialization operation. Also, if you want to set an operation other than the initial setting after this startup, use the key switch on the operation unit 12.
Operate 12b to set the desired mode.
When the mode is selected, information such as items indicating the mode is shown on the display 26.

In step S10, it is determined whether or not the two-frame shooting mode has been selected from the plurality of operation modes. 2
If the frame shooting mode is selected (YES), step S1
Proceed to 2. If a mode other than the two-frame shooting mode is selected (NO), the process proceeds to step S14. Step S14
Then, shooting is performed in the selected mode. After this processing, a standby state is set.

In step S12, by selecting this mode, the digital camera 10 is set to perform continuous shooting of two frames.
Is set. This set not only sets the continuous shooting, but also uses the key switch 12b to set the exposure when the first exposure and the exposure during the second frame are the same, and to set these exposures differently. Do. In the former case, selection of a captured image and / or setting of image synthesis are performed as described later. In the latter case, the setting is made in consideration of the expansion of the dynamic range. Here, in particular, for example, a setting is also made to give a step of ± 1/2 or ± 1/3 of the exposure at the time of bracketing to the appropriate exposure. The control and the procedure in the former setting and the latter setting will be described in subroutine SUB1 and subroutine SUB2, respectively.

Next, in step S16, photometry is performed on the object scene by the digital camera 10. This metering is performed by operating the aperture adjustment mechanism 200, the mechanical shutter mechanism 202, and the electronic shutter of the CCD 22 so that the CCD 22 can be irradiated with light in a so-called half-pressed state in which the shutter switch 12a is pressed to the first stage. The incident light at the value (for example, open) and the exposure time is photoelectrically converted by the CCD 22. After converting the analog signal obtained by the photoelectric conversion into a voltage level, this signal is supplied to the system control unit 16. The system controller 16 converts the amount of exposure light based on this signal. The system control unit 16 further determines whether or not the calculated exposure light amount is appropriate, and outputs a control signal to the drive signal generation unit 18 according to the determination result. The drive signal generation unit 18 supplies a drive signal to the light amount adjustment unit 20a and the light emission unit 20b of the exposure adjustment unit 20 according to the control signal. In the light amount adjustment unit 20a, an aperture value and an exposure time according to the drive signal are set. The incident light at the time of receiving this control is measured, and the above-described procedure is repeated. This is AE (Automatic Exposure) metering. Further, the preview on the display 26 is performed by supplying the photoelectrically converted signal to the signal processing unit 24 and displaying the signal processed signal.

The light emitting section 20b measures the light assuming that the strobe light is emitted. Shutter switch of operation unit 12
After the setting of the exposure is completed until 12a is pressed, the setting is kept in the standby state with the setting, and the process proceeds to step S18. Also,
When the subject is changed, it goes without saying that photometry is newly performed.

In step S18, the shutter switch 12a is pressed to the second stage at a desired timing to perform the main image pickup (so-called full-press state). At this time, the timing of the main imaging is supplied to the system control unit 16 via the system bus 10A. Shooting is performed with the mechanical shutter mechanism 202 and CCD
This is performed in combination with 22 electronic shutters. These relationships can be represented by a timing chart as shown in FIG. In photographing, the timing of turning on / off the mechanical shutter is synchronized with the vertical synchronizing signal VD and the horizontal synchronizing signal HD.
In this embodiment, the mechanical shutter is opened (level “H”) at the rising timing of the vertical synchronizing signal VD and the horizontal synchronizing signal HD.
)), And after the predetermined time, the electronic shutter is closed at the falling timing of the horizontal synchronizing signal. The electronic shutter is opened (level “H”) in synchronization with, for example, a high-speed clock signal. Set the timing and the time of the electronic shutter and the mechanical shutter
When exposing the CCD 22, exposure is performed only when both shutters are open so as not to block incident light. Therefore, at the timing shown in FIG. 4, the hatched area is the exposure period.

Next, in step S20, the process proceeds to a procedure according to the selected setting. In other words, when shooting is performed with the same setting for the selected exposure, the process proceeds to subroutine SUB1. If the selected setting is a setting for shooting with different exposure, the process proceeds to subroutine SUB2. Subroutine SU
In B1 and SUB2, a signal obtained by performing imaging according to each setting is read and output to the signal processing unit 24. Basically, as shown in FIG. 4, the reading of this signal is started in synchronization with, for example, the fall of the vertical synchronization signal VD after the end of the exposure. That is, since the light is shielded by the shutter at the time of signal reading as shown in FIG. 4, even an image pickup element for reading all pixels with a large smear can read a signal having no influence in a period of 1 VD. Further, since the CCD 22 is shielded from light because the mechanical shutter is in the closed state, reading may be performed over a time of 1 VD or more. As an example of this, a signal readout at 2VD is shown at the bottom. This means that the frequency of the drive signal in signal reading and the frequency of A / D conversion to be processed in the subsequent stage are reduced. This is because it is not necessary to increase the applied voltage used for processing such as readout.
Leads to lower power consumption. After this output, the process proceeds to subroutine SUB3. In step S14, a setting in another shooting mode different from the two-frame shooting mode is selected, and the process proceeds to step S22. In step S22, shooting is performed in the selected mode, and the flow advances to subroutine SUB3.

In the subroutine SUB3, the supplied signal is subjected to signal processing in a plurality of stages, and a procedure according to the setting is selected, and further, a process according to the selection is performed. The signal processing at each stage will be individually described in subroutine SUB3. The plurality of signal processes include at least image processing including analog signal processing, A / D conversion processing, digital signal processing, and buffer processing. Further, the procedure in this routine, that is, the condition as an index of which procedure of display and / or recording is to be performed, is performed in advance in the mode setting. This subroutine SUB3
Then, it is determined how to proceed the processing procedure according to the setting. The selection according to this judgment is performed. That is, for example, the selection is a selection of a procedure of first performing display-only preview, secondly displaying only an instant, and then recording both images or thirdly performing processing automatically including display and recording. is there. A subroutine SUB4 (see FIG. 10) is used for automatic image selection processing including recording.

In the signal processing section 24, when the combination of the image pickup signals is set by using the two processed image pickup signals (same exposure, non-same exposure), both images are combined and recorded on a recording medium. Either a procedure of recording the images on the recording medium 28 or a procedure of recording both images on the recording medium 28 later and reading and compositing these images from the recording medium 28 via an interface, for example, to a personal computer. Is selected. When a recording procedure is included in these selections, a compression process is performed on the imaging signal supplied from the image processing unit 24d.

Next, in subroutine SUB5, the display
A desired image is selected from the images displayed in 26. In this case, the selection is manually performed by the key switch 12b according to the subjective opinion of the user. Only in this case, the compression processing is not performed in the signal processing subroutine SUB3 because the display is prioritized. Therefore, since the signal processing is not completed, the imaging signal of the image selected by the key switch 12b is controlled by the system control unit 16 so as to be supplied from the image processing unit 24d to the compression processing unit 24e. The image data immediately before recording has been subjected to compression processing.

Next, in step S24, the supplied signal is recorded on the recording medium 28. After this processing, the flow advances to step S26. In step S26, it is determined whether or not a series of photographing processes is to be ended. For example, if the shutter switch 12a is half-pressed again, it is intended to continue shooting, so that the step shown in FIG.
Return to S16. Further, although not shown in the present embodiment, if it is desired to change to another mode setting, it is sufficient to return to before step S10. On the other hand, in step S24, when the operation unit 12 is not pressed for a predetermined time or when the power switch is turned off, the operation of the digital camera 10 is terminated.

Next, the operation of the above-described subroutines SUB1 to SUB5 in the digital camera 10 will be described in more detail.
In the subroutine SUB1 shown in FIG. 5, the mechanical shutter is opened after the photometry in step S16. In sub-step SS10, an open state period Ex of the mechanical shutter is set according to the time when the shutter switch 12a is pressed. This open state period Ex means that two frames are shot with the same exposure, so that the exposure time of the electronic shutter at the time of shooting the first frame obtained by metering along with the aperture value is doubled to the vertical synchronization period and signal. Set to the time obtained by adding the sweep pulse time. This time Ex can be seen from FIG. Also,
When shooting each frame with different exposure, the open state period Ex is
This is the time obtained by adding the vertical synchronization period and the signal sweep pulse time to the exposure time at the time of photographing the first frame (that is, the exposure time of the electronic shutter) and the exposure time at the time of photographing the second frame. After the setting according to the shutter timing, the process proceeds to sub-step SS12.

In sub-step SS12, a shutter switch
The electronic shutter is turned on in accordance with the drive signal at the timing when 12a is pressed. Thereby, the CCD 22 is irradiated with the incident light. This exposure time is Ex1. After the exposure time Ex1 has elapsed, the flow proceeds to sub-step SS14. In sub-step SS14, the electronic shutter is turned off. Thus, the exposure of the first frame is completed. The exposure of the first frame is controlled by an electronic shutter. After this, sub-step SS
At 16, the signal charge is transferred to the vertical transfer path. In this transfer, a field shift pulse is supplied as one of drive signals to a transfer gate provided between the pixel and the vertical transfer path (not shown) immediately after the end of the exposure. The signal charge stored in the pixel is transferred to a vertical transfer path via a transfer gate.

Next, in sub-step SS18, extra signal charges of the pixel are swept out. This sweep, for example,
A sweep pulse is supplied to each pixel during the period of the vertical synchronization signal VD. Each pixel has a vertical overflow drain (hereinafter referred to as VOD). When the sweep pulse is supplied, so-called substrate removal is performed in which excess signal charges are discarded to the substrate via the VOD. The sweep pulse is
The pulse has a polarity opposite to that of the vertical synchronization signal VD.

Next, in sub-step SS20, the exposure of the second frame is started, and the reading of the signal charges obtained by the exposure of the first frame is also started. The exposure of the second frame is also started by controlling the electronic shutter. However, the electronic shutter is kept open until the next vertical synchronization signal rises. The reading of the signal charge may take the time of 1 VD or 2 VD in the vertical synchronization period as described above (FIG. 6A).
See). After the elapse of the exposure time Ex2, sub-step SS
Proceed to 22.

In sub-step SS22, the exposure is immediately terminated. At this time, the shutter is controlled to be closed by a mechanical shutter. Thus, the exposure time Ex2 of the second frame is the same as that of the first frame (Ex1 =
Ex2). The time for the mechanical shutter to be in the closed state is set in advance based on the photographing condition of the same exposure amount as described above. Therefore, in the exposure of the second frame, the electronic shutter starts the open state as usual, but the transition to the closed state is controlled by the mechanical shutter. By controlling the mechanical shutter, the imaging of the second frame is performed completely without being affected by the incident light. On the other hand, also at this time, the signal reading of the first frame is continuing.

Next, in sub-step SS24, the signal of the second frame is read. This signal reading is started in synchronization with the falling timing of the vertical synchronization signal after the completion of the first frame signal reading. During the signal reading period of the second frame,
1VD is set as in the case of the first frame. After the completion of the signal reading, the flow shifts to return.

On the other hand, in the conventional all-pixel readout digital camera, when performing exposure control in the two-frame photographing mode using only the electronic shutter (however, the aperture value is fixed), FIG. Timing relationship. That is, when the same exposure is repeated twice with the vertical synchronizing signal VD, the CCD performing the all-pixel reading may have a possibility that smear may occur due to the incident light affecting the imaging when the image is captured by the electronic shutter. that before the exposure start of the second frame takes a predetermined time t _D in order to remove this effect are known. For this reason, even in the case of two-frame continuous exposure, intermittent imaging occurs with a shooting interval. It is not possible to continuously photograph a subject at substantially the same timing without time lag.

Next, the operation of the subroutine SUB2 will be briefly described. Basic operation of subroutine SUB2 (substep
SS100 to SS114) are the same as the operation of the above-described subroutine SUB1 as shown in FIG. Therefore, the description of the detailed operation procedure is omitted. However, even if the mechanical shutter is opened in the same period Ex, the difference is that the exposure time Ex3 of the first frame and the exposure time Ex4 of the second frame in this case are not the same. That is, as for the exposure times Ex3 and Ex4 of each frame in FIG. 8A, the exposure time Ex3 is longer than the exposure time Ex4. In FIG. 8B, the exposure time Ex4 is larger than the exposure time Ex4.
Set longer than 3. However, in this case, there is a possibility that the influence of smear may appear significantly in the captured image of the second frame. If the difference between the two exposures is n times as described above, the dynamic range can be easily expanded as described later. The timing chart of FIG. 8A shows, for example, a case where shooting is performed by setting conditions for shooting at an appropriate normal exposure first and then at a double shutter speed. Exposure is performed with settings according to the respective photographing conditions. Such exposure control is the same when, for example, bracketing is performed. Bracketing is performed with one exposure amount set to ± 1/2 or ± 1/3 for the other exposure amount. The difference with respect to one of the exposure amounts is _ΔEx shown in FIG.

Next, the operation procedure of the signal processing will be described with reference to the subroutine SUB3 of FIG. In the subroutine SUB3, a flag is used to divide the procedure of the display / compression processing. First, in sub-step SS300, it is checked whether or not the value of the flag is 0. Substep when flag value is 0
Proceed to SS302. If the value of the flag is not 0, the flow advances to sub-step SS326 via connector A.

In sub-step SS302, the supplied signal is subjected to CDS processing. The signal is transmitted to the A / D converter 24b with the quality of the analog signal being improved by noise countermeasure processing called correlated double sampling in the analog converter 24a. Thereafter, the process proceeds to sub-step SS304. Substep
In SS304, the supplied signal is converted into a digital signal. The converted signal is output to the digital processing unit 24c. This digital signal is applied to substep SS306
Receives a pixel interpolation process for each color. Digital camera 10
Is a single-panel type, since the CCD 22 image sensor can only perform photoelectric conversion on one of the separated RGB colors, the digital processing unit 24c calculates the other two colors by interpolation and calculates each of the RGB plane images. Generates the image processing unit 24d
Output to Next, in sub-step SS308, data supplied for each imaged frame is temporarily stored. One frame may be stored in a non-volatile frame memory corresponding to each of the three primary colors RGB. The image processing unit 24d supplies the data stored in the buffer memory to the arithmetic unit under the control of the system control unit 16. The calculation unit performs various calculations according to preset conditions. The calculation according to this condition will be described below.

Next, in sub-step SS310, it is determined whether or not to select an image obtained by capturing two frames.
If an image is to be selected (YES), the flow advances to substep SS312. If image selection is not performed (NO), the flow proceeds to sub-step SS314. In sub-step SS312,
It is determined whether or not the frame has been imaged with the same exposure.
If the imaging conditions (exposure) of the two frames are the same (YES), the flow advances to sub-step SS316. In addition, imaging conditions for two frames (exposure)
Are different (NO), the flow proceeds to substep SS318. In sub-step SS316, it is determined whether or not the user makes a subjective selection for the two captured frames. Here, the subjective selection refers to making a selection decision by looking at the obtained image. When performing subjective selection (YES), sub-step SS320
Proceed to. When the automatic selection is performed without performing the subjective selection of the image (NO), the process proceeds to the subroutine SUB4.

In sub-step SS320, two frames of image data in the corresponding buffer memory are sent to the display 26. In the next substep SS322, a flag is set for the transmitted image data. The value to set is
For example, 1. After this processing, the process returns to the return.

On the other hand, in sub-step SS318, it is determined whether or not the image is an image picked up by bracketing. If bracketing is selected from the imaging condition settings (YE
S), proceed to sub-step SS324. If bracketing has not been selected (NO), sub-step SS32
Proceed to 6. In sub-step SS324, it is determined whether to select from two frames. This determination is also set in advance when setting the conditions. When selecting using the set value when displaying the captured image (YES), the sub-step
Proceed to SS328. Also, if you make this selection later (NO),
Proceed to sub-step SS326. In sub-step SS328,
2 in the buffer memory corresponding to the image processing unit 24d.
The image data of the frame is transmitted to the display 26. In the next substep SS322, a flag is set for the transmitted image data. The value to set is, for example, 1. After this processing, the process returns to the return.

If the determination in sub-step SS316 is not a subjective selection, the flow proceeds to the automatic selection processing of subroutine SUB4 shown in FIG. In the automatic selection of the subroutine SUB4, a process of supplying the image data selected from the image processing unit 24d to the compression processing unit 24e in the sub-step SS400 is performed. Compression processing unit 24
In this embodiment, JPEG is used for the compression processing in e.

Next, in sub-step SS402, as described above, the frequency analysis is performed on each image data using the conversion table obtained during the JPEG processing. Next substep SS
In 404, as a result of this frequency analysis, focusing on the high frequency range in the band, the level representative value of the base vector indicating the frequency range higher than a certain frequency is integrated. Then sub-step SS
At 404, the count value obtained by integrating the level representative value is compared with a predetermined value, and it is determined for each image whether the count value is larger than the predetermined value. When the comparison result is true (YE
S), proceed to sub-step SS408. If the comparison result is false,
That is, when the count value is equal to or less than the predetermined value (NO), the process proceeds to sub-step SS410.

In sub-step SS408, it is determined whether image data including a high-frequency component exceeding a predetermined value corresponds to both frames. When both contain high frequency components (YES
), Proceed to sub-step SS412. When only one image has been supplied (NO), the flow proceeds to sub-step SS414. In sub-step SS410, which deals with a case where image data whose count value is equal to or smaller than the predetermined value in the previous comparison is supplied, the data is discarded as inconvenient data. In this case, the image data is deleted. After that, the process moves to return.

These processes are performed when the image data is supplied to the display 26 and displayed, for example, as shown in FIG.
It is displayed as shown in (B). FIG. 11 also shows the result of frequency analysis of the image data together with the display. Obviously, the image shown in FIG. 11 (A) is blurred. Further, the image does not include a high frequency component. On the other hand, the image of FIG. 11B contains high frequency components. The actual image is also clear.

In sub-step SS412, an image is selected. Here, since the two frames each include a high-frequency component more than a predetermined value, either one may be used, but the image having the larger count value is selected from the two frames (images). Next, in sub-step SS416, the selected image data is sent to the display 26. This sending control is
This is performed by the system control unit 16. After this transmission, the process moves to return. Also, the same processing as sub-step SS416 is performed in sub-step SS414. That is, the display data is stored in the buffer memory where the selected image data is stored
Send to 26. After this transmission, the process moves to return.

After the return in subroutine SUB4, the process proceeds to substep SS322. In sub-step SS322, the flag is set to 1 as described above, and the flow shifts to return.

By the way, if bracketing is not determined in sub-step SS318 or if selection is made in another process after recording based on determination in sub-step SS324, the process proceeds to sub-step SS326. In this case, compression processing (JPEG) is performed on two frames of image data. After this processing, the flow advances to sub-step SS330. In sub-step SS330, the flag is set to 0. After that, the process moves to return. Image selection is performed in such a procedure.

In the subroutine SUB3 for performing signal processing, for example, an image synthesizing process is also performed as other signal processing. This procedure is started based on the judgment in sub-step SS312. If image selection is not performed in sub-step SS312 (NO), the process proceeds to sub-step SS314 as described above. In sub-step SS314, it is determined whether to perform image synthesis. Judgment can be made easily because the setting is made according to the shooting conditions. When performing image synthesis (YES), the image synthesis proceeds to sub-step SS332.
In the case of neither image selection nor image synthesis processing (N
O) Go to substep SS326.

In sub-step SS332, it is determined whether or not the digital camera 10 is to perform synthesis. If the camera 10 is used (YES), the flow advances to sub-step SS334. If the combining process is to be performed later without performing the process by the camera 10 (NO), the process proceeds to sub-step SS326. Sub-step SS33
In step 4, it is determined whether or not the supplied shooting conditions are the same. That is, when the same exposure is supplied (YES
), And proceed to sub-step SS336. Sub-step SS336
Then, S / N improvement processing is performed using the supplied image data. A simple S / N improvement process includes a process of adding supplied two frames of image data and dividing by two (addition averaging process).

Incidentally, there is a possibility that the subject may move during the continuous imaging of two frames. In the S / N improvement processing in consideration of this possibility, although not shown, the difference between the first two supplied images is calculated. Next, the calculated result is compared with a predetermined difference value set in advance. By this comparison, the calculation result is divided into a portion larger than the predetermined difference value and a portion smaller than the predetermined difference value. The above-described averaging process is not performed on this large portion, and one of the images is used. Also,
An averaging process is performed on a portion having a predetermined difference value or less. Such processing may be performed. The portion subjected to the averaging process can improve the S / N ratio of the image by 3 dB. After this processing, the flow advances to sub-step SS326.

Further, it has been described that when it is determined that the exposure is not the same in sub-step SS334 (NO), the process proceeds to sub-step SS338. In sub-step SS338, it is determined whether to perform the process of expanding the dynamic range. If the setting is to expand the dynamic range (YES),
Proceed to SS340. If the dynamic range is not expanded (NO), the flow proceeds to sub-step SS326. Substep
In the SS340, two frames having different exposures are supplied, and under the control of the system control unit 16, these two images are combined to generate an image having a wide dynamic range. In the present embodiment, the subsequent processing is the sub-step SS326, but the display 26 may display the synthesis result. In this case, the process may jump to sub-step SS322.

In the sub-step SS326, the image data subjected to the compression processing is output, and the flow shifts to the return through the sub-step SS330. In the case of combining images, the sub-step SUB3 is completed via a return by operating the above procedure. Image data digitally processed according to this procedure is supplied to the display 26.

Next, selection of an image on the display 26 will be described with reference to a subroutine SUB5 of FIG. First, in sub-step SS500, confirmation and determination are made as to whether the value of the flag is 1. When the value of the flag is 1 (YES), the process proceeds to sub-step SS502. When the value of the flag is not 1 (NO), it is determined that no image is selected, and
Move to return. If image data that has not been compressed is supplied, the sub-step SS336
Alternatively, it may be displayed on the display 26 as a processing result of the sub-step SS340.

In sub-step SS502, the supplied image data is displayed on the display 26. This display is 1
The frame and / or two frame images are displayed on the display 26. As a specific example, the system control unit 16 switches and displays the supplied frames one by one at a predetermined time.
Then, two frames are displayed on one screen (for example,
11, see FIGS. 13-15). FIG. 13 shows a case where two frames of (A) an image having a camera shake and (B) an image having no camera shake, which slightly move at the moment when the shutter is released, are captured. For example, a camera with a camera shake correction function prevents a camera shake and obtains a normal image by taking measures such as increasing the shutter speed and increasing the stability of the camera itself.

By the way, in the two-frame shooting mode of the present embodiment, two frames are continuously photographed, so that even if one frame cannot be used, the other frame may be normally photographed without camera shake. .

In FIG. 14, there is no camera shake, but (A) an image in which a child has closed his eyes and (B) a normally captured image in which the subject is not blinking are obtained. It is. As described above, even if one frame is closed, the other frame is open. Further, FIG. 15 shows an image at the moment when a soccer player tries to kick a ball.
These two frames are images when the imaging conditions are different.
(A) shows a case where the image was taken with a high-speed shutter, and (B) shows a case where the image was taken with a low-speed shutter having a long exposure time. The following selections are described using these images. However, although the image automatically selected in the subroutine SUB4 is not specifically shown, the selected image is displayed for a predetermined period of time, and the process proceeds to return.

Next, in sub-step SS504, an item for selecting an image and a cursor are displayed together with the supplied image. Only images are displayed on the drawings of FIGS. 11, 13 to 15, and the above-mentioned items and cursors are not shown. Thereafter, the flow advances to sub-step SS506. In sub-step SS506, a desired frame is selected. Whether this selection is made or not is made by selecting the item at the position where the cursor is moved. When selecting an image (YES), the process proceeds to sub-step SS508. Also,
If no image is selected (NO), the flow advances to substep SS510. In the case of such an image as shown in FIG. 15, one or both of the images may be left depending on the intention of the photographed user.

In sub-step SS508, it is determined which frame to select by item. Place the cursor on the item (or the image itself) and select it. The result of the selection is supplied as a selection signal to the system control unit 16 via the system bus 10A. After this selection, go to return. In the images of FIGS. 11, 13 and 14, the user selects the image on the (B) side.

Sub-step SS510 is a case where both frames are recorded. Also in this case, a selection signal is supplied to the system control unit 16 so as to record both. After this selection, proceed to subroutine SUB3. Here, the value of the flag is
Since it is 1, the process proceeds to sub-step SS326 via connector A, immediately performs compression processing, and returns to the return via flag processing in sub-step SS330. However, control is performed so that the image that has been subjected to the compression processing in the previous subroutine SUB3 is not subjected to the compression processing. Other flags may be used for this control. Subroutine SU after this return
Move to B5 return. After the return, this subroutine SUB5 ends. Thereafter, as described above, only the compressed desired image is recorded in the memory of the recording medium 28.

With the above-described configuration, the CCD for reading out all the pixels when the image is captured in the continuous two-frame imaging mode.
Exposure is terminated by a mechanical shutter to prevent light from leaking into the image obtained in step (1), thereby preventing smear that easily occurs in the image. As a result, the time interval required for continuous imaging is almost eliminated, and for example, imaging can be performed in synchronization with the timing of the vertical synchronization signal.
Further, the obtained signal charges can be read out in a sufficiently long time, so that high-speed reading can be omitted. Thus, the applied voltage can be suppressed, and the clock required for A / D conversion can be performed at a realistic frequency. Therefore, the power consumption required for imaging by the camera can be reduced.

Further, since two images are continuously obtained in this manner, if one of the captured images is photographed under the same photographing condition and the other is normally photographed, there is a problem. By recording the other image, relief of shooting can be performed. Then, when a desired image is recorded on a recording medium by performing selection / automatic selection by a user, the capacity of the recording medium can be effectively used.

Further, after photographing under different photographing conditions, a process of synthesizing the two images is performed, so that the dynamic range can be expanded, the image having a high S / N ratio, and bracketing can be easily performed. The processing for these two images may be performed not only by the camera, but also by reproducing the once recorded image on a computer and synthesizing it. By performing such processing, the quality of the obtained image can be made higher than that of a single image.

[0087]

As described above, according to the solid-state imaging device of the present invention, the photographing conditions are set and the photographing timing is selected by the operation means, and the amount of exposure light supplied to the photographing means is determined in accordance with these. Adjustment is performed. In the light amount adjusting means, a predetermined aperture value which has been set and an incident light capturing time, which is another parameter for the predetermined aperture value, are first open / close setting means and a second which mechanically sets the incident light capturing time. Is adjusted by the operation of the open / close setting means.
That is, for example, in the case of taking two consecutive shots, the first exposure sets the second opening / closing setting means to the open state, and sets the opening / closing period of the first opening / closing setting means to the exposure time. The opening state is set at the timing of the opening / closing setting means, the state is closed by the second opening / closing setting means, and the photographing is terminated. Since the second shooting is completely shielded at the end of shooting, smear caused by the influence of leaking light can be prevented even when the electronic shutter is closed at the time of signal reading, as compared with a case without a mechanical shutter. The large shooting interval that has been set can be eliminated. Moreover, high-speed reading can be avoided by taking a long time for signal reading, so that power consumption can be suppressed. This also allows the signal processing means to select only the image desired by the user without waste. More specifically, for example, it is possible to easily perform camera shake correction in an image, relieve blinking or blurring of a subject, imaging with a wide dynamic range, imaging with a high S / N ratio, bracketing, and the like.

Further, according to the photographing control method of the present invention, the photographing conditions are set, and the first exposure light amount and the second exposure light are set to a predetermined value according to the set photographing conditions and the capturing time of the incident light. Driving signals for adjusting the light amount are set in advance, and the first photographing is performed at the timing of the first driving signal. After the completion of the exposure, the obtained signal charges are read out to the vertical transfer path of the imaging means, and the next exposure is performed. The extra signal charges are removed in preparation for. Then, the second imaging is performed by starting imaging with the third drive signal and ending imaging with the fourth drive signal, and reading out the obtained signal charges from the imaging means.
By this processing, in particular, in the second shooting, while supplying the timing to mechanically end the shooting with the fourth drive signal,
It also blocks physical light. Thereby, when reading out the signal charges obtained by the second photographing to the vertical transfer path of the imaging means, it is possible to prevent light leakage and to suppress the influence of smear which is likely to occur in reading out all pixels. In addition, this makes it possible to minimize the first and second photographing intervals, and to obtain an image with little time lag. Further, the obtained signal charges are subjected to signal processing, and only one or both of the obtained images are selected to record only effective photographing,
It is possible to obtain image data of higher image quality than an image obtained under one shooting condition. Therefore, the user can effectively use the capacity of the recording medium. Since reading is performed in a sufficient time for signal reading, application of high voltage can be avoided and power consumption can be suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a digital camera to which a solid-state imaging device according to the present invention is applied.

FIG. 2 is a block diagram of a schematic configuration showing a light amount adjustment unit of FIG. 1 according to functions.

FIG. 3 is a main flowchart illustrating a procedure for operating the digital camera in FIG. 1 in a two-frame shooting mode.

FIG. 4 is a timing chart illustrating a basic timing relationship until a signal is read out using an electronic shutter and a mechanical shutter, generally including the digital camera of FIG. 1;

FIG. 5 is a flowchart illustrating an operation in a subroutine SUB1 used when performing the same exposure shooting in FIG. 3;

FIG. 6 is a timing chart illustrating a timing relationship between the operation of FIG. 5 and a conventional operation.

FIG. 7 is a flowchart illustrating an operation in a subroutine SUB2 used when performing different exposure shooting in FIG. 3;

FIG. 8 is a timing chart for explaining the timing relationship of the operation of FIG. 7;

FIG. 9 is a subroutine in the two-frame shooting mode of FIG. 3;
9 is a flowchart illustrating a procedure of image processing of SUB3.

FIG. 10 is a flowchart illustrating a procedure of automatic selection (subroutine SUB4) of an image used in subroutine SUB3 of FIG. 9;

11 is a diagram illustrating the relationship between a frequency distribution obtained when automatic selection is performed in FIG. 10 and an image thereof.

12 is a flowchart illustrating a procedure of image display of a subroutine SUB5 and an image selection process in the two-frame shooting mode in FIG. 3;

13A and 13B are diagrams showing (A) an image in which a child of a subject is blurred and (B) a normal image in two consecutive frames obtained by operating according to the procedure of FIG. 3;

14 is a diagram showing (A) an image in which a child of a subject has closed his eyes and (B) a normal image in two consecutive frames obtained by operating according to the procedure of FIG. 3;

FIG. 15 is a view showing (A) a clear image of a soccer player and (B) an image of a soccer player full of presence in two consecutive frames of a soccer player kicking a ball obtained by operating the procedure of FIG. 3; is there.

[Explanation of symbols]

 10 Digital camera 12 Operation unit 14 Optical lens 16 System control unit 18 Drive signal generation unit 20 Exposure adjustment unit 22 CCD 24 Signal processing unit 26 Display 28 Recording medium 20a Light intensity adjustment unit 20b Light emission unit 200 Aperture adjustment mechanism 202 Mechanical shutter mechanism 204 Electronics Shutter function section

Claims (17)

[Claims] 1. An incident light from a field to be supplied is condensed by an optical system, the light condensed by the optical system is photoelectrically converted by an image pickup means, and all of the signal charges obtained by the photoelectric conversion are converted. In a solid-state imaging device that performs image capturing by pixel readout, the device includes: an operating unit that operates to set an image capturing condition of the device and select a timing of the image capturing; Exposure light amount of incident light supplied to the imaging means,
First opening / closing in which the setting of the start / stop of taking in of the imaging means with respect to a predetermined aperture value set when combined with an aperture value representing the transmission cross-sectional area of the incident light is electrically set as the time of capturing the incident light. A setting unit and a light amount adjusting unit that adjusts by a second opening / closing unit that mechanically sets a capturing time of the incident light; a capturing period of the incident light supplied to the imaging unit via the light amount adjusting unit; A drive signal for reading out signal charges obtained by photoelectric conversion of incident light and a drive signal generating means for generating a drive signal for adjusting the light amount adjusting means to the aperture value; and a signal charge from the imaging means. Signal processing means for performing signal processing; and control means for controlling the drive signal generation means and the signal processing means in accordance with information from the operation means, The setting means sets the first exposure time in the adjustment of the exposure light amount when taking two consecutive shots, and the second opening / closing setting means determines the end timing of the second shooting. Characteristic solid-state imaging device. 2. The apparatus according to claim 1, wherein the first opening / closing setting means is an electronic shutter for electrically starting / stopping the capture of the incident light, and wherein the second opening / closing setting means includes: A solid-state imaging device, comprising: a mechanical shutter mechanism for continuing the incident light enterable state for at least a longer time than the incident light capturing time according to the aperture value. 3. The apparatus according to claim 1, wherein the light amount adjusting means includes a light emitting means for emitting light by compensating for a light amount difference generated between the light amount from the object field and the light amount under the photographing condition. A solid-state imaging device characterized by the above-mentioned. 4. The apparatus according to claim 1, wherein the operation unit supplies a shooting timing of the object scene.
A solid-state imaging device, comprising: an operation selecting unit for setting a photographing condition of the object scene and selecting a photographed image. 5. The apparatus according to claim 1, wherein said signal processing means performs analog signal processing on the supplied signal charges, and digitally converts an output from said analog processing means into a digital signal. Converting means; digital processing means for performing digital signal processing on the digital signal from the digital converting means; time adjusting means for storing and outputting two imaging signals supplied from the digital processing means; Signal analysis means for analyzing frequency components of individual imaging signals supplied from the means, and selecting an imaging signal containing more high frequency components among the frequency-analyzed imaging signals. Solid-state imaging device. 6. An incident light from a field to be supplied is condensed by an optical system, and a light amount of the incident light is supplied by adjusting an exposure light amount in accordance with a photographing condition. Is photoelectrically converted into a signal charge which is an electric signal, and the reading of the signal charge is performed by reading out all pixels. And a stop drive signal for setting a predetermined value as a stop value representing the size of the transmission cross-sectional area of the incident light according to the photographing conditions set in the condition setting step, and the capture start / stop. A first signal generating step of generating a first drive signal contributing to electrical adjustment and a second drive signal contributing to mechanical adjustment of the first exposure light amount by setting the capture time of the incident light, respectively; , Set in the condition setting step A third drive signal and a mechanical drive, each of which contributes to electrical adjustment of an aperture drive signal for setting the next predetermined value according to the obtained photographing condition, and a second exposure light amount by setting the capture time of the incident light. A second signal generation step of generating a fourth drive signal contributing to adjustment is set in advance, and a timing for generating a timing signal indicating a shooting timing of the object scene under the shooting conditions of the object scene Determining step, the aperture drive signal generated in the timing determining step,
A first photographing step of performing a first photographing according to a timing of the first drive signal of the first and the second drive signals; and after the first photographing, the photographing is performed by the photographing. A first signal transfer step of reading out the prepared signal charges to the vertical transfer path of the prepared imaging means; and a signal removing step of removing excess signal charges in preparation for the next exposure after the first signal transfer step; After the signal removing step, the diaphragm drive signal is supplied as a second photographing step, photographing is started at the timing of starting photographing of the supplied third drive signal, and photographing end of the fourth drive signal is completed. Performing a second image capturing operation to end the image capturing at the timing of, and reading out the signal charges moved in the first signal moving step from the image pickup unit; and terminating the first signal reading step. Later, by the second photography A second signal movement step of reading out the obtained signal charges to the vertical transfer path of the imaging means; and, after the second signal movement step, the signal charges moved in the second signal movement step are read by the imaging means. A second signal reading step of reading from the first and second signal reading steps, and a signal processing step of performing signal processing on the signal charges obtained by the first and second signal reading steps, respectively. A photographing control method, wherein one or both of the images obtained in the second signal reading step are selected. 7. The method according to claim 6, wherein the timing signal is generated based on a vertical synchronization signal after performing the shooting operation as a timing reference. 8. The method according to claim 6, wherein the fourth drive signal is in a state where the incident light can be incident at the same time as the start of the acquisition of the incident light set by the second drive signal. A photographing control method, wherein the incident enabling state is continued until the photographing end timing. 9. The method according to claim 6, wherein the signal processing step includes performing an analog signal processing on the supplied signal charges, and converting the output signal after the analog step into a digital signal. A digital process for performing digital processing on the digital signal obtained by the conversion process; and after the digital process, the first and / or the second
A timing adjustment step of temporarily holding and outputting the output signal of the imaging step, and performing a frequency analysis on the imaging signal supplied through the timing adjustment step, and a high-frequency component based on the obtained analysis result. A signal selecting step of selecting an image pickup signal that is included in a larger number of times. 10. The method according to claim 9, wherein the signal selecting step uses a frequency analysis function when performing compression processing on the selected image signal. 11. The method according to claim 9, wherein, after the timing adjustment step, the signal processing step includes a display step of displaying two image signals output to a prepared display means. An image selection step of selecting one or both of the displayed images; a compression step of performing a compression process on an image signal of the image selected in the image selection step; and a recording medium storing the compressed image signal after the compression step. A photographing control method characterized by sequentially performing a recording step of recording in a camera. 12. The method according to claim 6, wherein the signal processing step includes an image synthesizing step of synthesizing two output imaging signals after the timing adjusting step. 13. The method according to claim 12, wherein, in the image synthesizing step, when the first and second signal generation steps perform shooting with the same amount of exposure light, two obtained imaging signals are obtained. A photographing control method comprising an averaging step of taking an averaging of. 14. The method according to claim 13, wherein the averaging step includes: an image difference step of calculating a difference between the obtained two imaging signals; and a difference value obtained by the image difference step is a predetermined value. A determination step of determining whether the two imaging signals are smaller than the predetermined value, and performing the averaging only when the result of the determination step is smaller than the predetermined value. A photographing control method, wherein one of the imaging signals is supplied to the signal selecting step or the image selecting step to select one of the imaging signals. 15. The method according to claim 6, wherein the first signal generation step and the second signal generation step include one of the first signal generation step and the second signal generation step. And setting the other exposure light quantity to an exposure light quantity having a difference from the normal appropriate exposure light quantity. 16. The method according to claim 15, wherein the difference with respect to the normal proper exposure light amount is a first aperture value indicating the normal proper exposure, and each of the adjacent aperture values before and after the first aperture value. 1/2 or 1/3 of the distance from the selected aperture value to the second
Wherein the second aperture value is set by the first and second drive signals or the third and fourth drive signals, respectively. 17. The method according to claim 6, wherein the first and second signal reading steps are set so that each signal reading period is read over a plurality of vertical synchronization periods. Method.