JP2003169248A - Imaging device, imaging method, computer-readable storage medium, and computer program - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When a high-speed electronic shutter is set, a frame still image can be shot without changing the setting of the electronic shutter. SOLUTION: In an imaging apparatus having a mechanical shutter and an electronic shutter, if the electronic shutter is set to an exposure time shorter than the time until the mechanical shutter is fully closed, the fully closing operation of the mechanical shutter ends. Until the reading, the exposure is continued in a state of waiting for reading, and the video signal of the odd field and the video signal of the even field are read in order from the next field after the field waiting for the reading, and the odd field is read. In a frame still image synthesized from the video signal of the image field and the video signal of the even field, a luminance step between lines is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, an image pickup method, a computer-readable storage medium, and a computer program, and is particularly suitable for use in an image pickup apparatus such as a digital still camera capable of shooting a digital still image. is there.

[0002]

2. Description of the Related Art Conventionally, various processes have been performed at the timing shown in FIG. 4 for still image shooting by frame reading using an image pickup device capable of interlaced reading.

First, the exposure is interrupted by using a mechanical shutter which also serves as an aperture, while accumulating in the image pickup device within one field period. The reason why the last part of the exposure is cut off is that the light is blocked by the operation of the mechanical shutter (period in FIG. 4).

Secondly, the video signal of each field (ODD field and EVEN field) is read out from the image pickup device by utilizing the period of 2 fields (the period of FIG. 4).

In the subsequent processing, the CDS / AGC circuit electrically amplifies the video signal, and the A / D converter converts it into a digital signal. Then, the video signal converted into the digital signal is transferred to the memory through the camera signal processing unit, and the video signals of the two fields are combined as one frame image to generate a still image. The generated still image is recorded in a data recording unit such as a flash memory in the image recording unit.

[0006]

However, when the aperture is also used as a mechanical shutter, the aperture of the aperture varies depending on the exposure state, and the mechanical shutter operation depends on the aperture. The time it takes to fully close the aperture changes when you go. Further, in principle, a mechanical shutter using an aperture will be extremely underexposed unless the aperture closing operation is started after the exposure start time.

Therefore, when the exposure time is extremely short due to the setting of the electronic shutter, it is necessary to change the speed of the electronic shutter so that the closing operation of the mechanical shutter can sufficiently follow when photographing a still image. There is a problem that it is difficult to instantly adjust to an appropriate exposure due to a change.

Further, when the electronic shutter is not changed, the time from the start of the closing operation of the diaphragm as the mechanical shutter to the full closing becomes longer than the exposure time with respect to the exposure time. The operation state and timing at this time are shown in FIG.

As shown in FIG. 5, when the electronic high-speed shutter operation is performed, the exposure in the first half of the field period is swept away, and the exposure of the image pickup element is performed in the latter half of the field defined by the electronic shutter. Done. Further, the mechanical shutter starts the fully closing operation at a specified timing (Fig. 5).

Then, the reading of the video signal of the ODD field starts in the next field, but the video signal read here is only the exposure for the period of FIG. At the start timing of this field, the mechanical shutter is not fully closed yet, so the exposure of the image sensor continues (FIG. 5).

Next, the video signal of the EVEN field is read out. Since the video signal read out here is the exposure of the image pickup device in the periods of and in FIG.
The level is different from the video signal of the ODD field read before the field (FIG. 5).

As described above, since the mechanical shutter is not fully closed even during the reading period of the ODD field, exposure is performed, so that the video signal read in the ODD field is not detected. EV
There is a problem that an exposure difference occurs between the video signal read in the EN field and the exposure signal.

As a result, in the case of the conventional image pickup device, 1
Image ODD / E when combined into a single frame still image
There is an inconvenience that a luminance step is generated between the VEN lines.

In view of the above problems, it is an object of the present invention to enable frame still image shooting without changing the setting of the electronic shutter when the high-speed electronic shutter is set. To do.

[0015]

An image pickup apparatus of the present invention is an image pickup apparatus having a mechanical shutter and an electronic shutter, wherein the electronic shutter is used for an exposure time shorter than a time until the mechanical shutter is fully closed. If it is set, exposure is continued in the state of waiting for reading until the completion of the full closing operation of the mechanical shutter, and the video signal of the odd field and the even field The feature is that the reading is performed in the order of the video signals. Another feature of the present invention is an image pickup apparatus which has a mechanical shutter and an electronic shutter and which performs frame reading using an image sensor capable of interlace reading, wherein the exposure to the image sensor is reduced. A mechanical shutter that is interrupted by a mechanical shutter, a mechanical shutter operation control unit that controls the operation of the mechanical shutter, and an electronic shutter speed control unit that can electrically control the exposure time of the image sensor, and the exposure time of the electronic shutter. However, when the exposure time is set faster than the operable exposure time of the mechanical shutter operation control means, after performing the accumulation operation over a plurality of fields, the video signal of the odd field and the video signal of the even field The feature is that frame reading is performed in the order of It is.

The image pickup method of the present invention is an image pickup method using an image pickup device having a mechanical shutter and an electronic shutter, wherein the electronic shutter is set to an exposure time shorter than the time until the mechanical shutter is fully closed. If so, the exposure is continued in the state of waiting for reading until the completion of the fully closing operation of the mechanical shutter, and the video signal of the odd field and the image of the even field from the next field after the field waiting for the reading is finished. The feature is that the signals are read in the order of signals.

The storage medium of the present invention is characterized by recording a program for causing a computer to execute the method described above.

The computer program of the present invention is characterized by causing a computer to execute the method described above.

Since the present invention has the above-mentioned technical means, by starting the reading from the field next to the field in which the fully closing operation of the mechanical shutter is completed, a suitable frame still image in which no luminance step between fields occurs is generated. It becomes possible to obtain.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an image pickup apparatus, an image pickup method, a computer-readable storage medium, and a computer program according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an example of an image pickup apparatus according to the present invention. As shown in FIG. 1, the image pickup apparatus according to the present embodiment includes a lens 101, a diaphragm 102, and an image pickup element 1.
03, CDS / AGC104, A / D converter 10
5, a camera signal processing unit 106, an image recording unit 107, a memory 108, a camera control unit 109, a timing generator (TG) 110, and the like.

According to the image pickup apparatus of the present embodiment configured as described above, the image pickup device 10 is formed within one field period.
At the same time as the accumulation in 3, the exposure is interrupted by using the mechanical shutter 102 that also serves as the diaphragm.

Next, the video signal of each field (ODD field and EVEN field) is read from the image pickup device 103 by utilizing the period of 2 fields. In the subsequent processing, the CDS / AGC circuit 104 electrically amplifies the video signal, and the A / D converter 105 converts it into a digital signal.

Thereafter, the video signal converted into a digital signal is transferred to the memory 108 via the camera signal processing unit 106, and the video signals of two fields are combined as one frame image to generate a still image. The still image generated in this way is recorded in a data recording medium such as a flash memory by the image recording unit 107.

According to the image pickup apparatus of the present embodiment, when the electronic shutter is set to an exposure time shorter than the follow-up time of the mechanical shutter until the fully closed time, the field for starting the fully closed operation of the mechanical shutter is set. Instead of starting reading from the field next to
It operates like.

That is, first, since the electronic high-speed shutter operation is performed, the exposure of the first half within the field period is swept away, and the exposure of the image pickup device is performed during the latter half of the field defined by the electronic shutter. Also,
The mechanical shutter starts the fully closing operation at the specified timing (Fig. 2).

Next, in the next field as well, since the fully closing operation of the mechanical shutter is not completed, ODD
The field image signal is not read out, and the exposure is continued in the read standby state (FIG. 2).

Next, the video signals of the ODD field and the EVEN field are sequentially read from the next field after the read standby field is completed (FIG. 2).

The control operation of the camera control unit 109 will be described below with reference to the flowchart of FIG. In the first step (501), the camera control unit 109 sets the time t until the aperture is fully closed when the mechanical shutter operation is performed from the current opening of the aperture 102 at the start of still image shooting. The calculation is performed from the data table recorded in the internal memory, and the result is stored in the variable t.

Next, in step (502), the exposure time T of the image pickup device is calculated from the electronic shutter speed of the image pickup device currently set, and the result is stored in the variable T.

Next, in step (503), the exposure start time of the image pickup device is calculated from the beginning of the field (timing of the falling edge of the VD signal pulse) from the electronic shutter speed of the image pickup device that is currently set, and it is calculated. Based on the above, the mechanical shutter closing operation start timing X of the diaphragm 102 is calculated. Then, the result is stored in the variable X.

Next, at step (504), the mechanical shutter closing operation start timing X of the diaphragm 102 is started.
Wait until time.

When the closing operation start timing is reached, the process proceeds to step (505) to start the mechanical shutter closing operation of the diaphragm 102.

Next, at step (506), the time t until the mechanical shutter fully-closed operation calculated above is calculated.
And the exposure time T of the image sensor according to the setting of the electronic shutter speed. As a result of this comparison, if t ≧ T, the process proceeds to step (507) to wait for the operation for one field period.

Further, as a result of the comparison in step (506), t
If T, proceed to step (508) without waiting,
The reading operation of the image sensor is started from the next field. That is, the video signal of the ODD field is read from the image sensor.

Next, in step (509), the EVE
The video signal of N field is read from the image sensor. In the subsequent processing, the same processing as the conventional processing is performed to generate a frame-combined still image.

(Other Embodiments of the Present Invention) The present invention may be applied to a system including a plurality of devices or an apparatus including a single device.

Further, the functions of the above-described embodiments are realized for a computer in an apparatus or system connected to the above-mentioned various devices so that the various devices are operated so as to realize the functions of the above-described embodiments. Computer program (CPU or MP) of the system or device is supplied.
Those implemented by operating the above various devices according to the program stored in U) are also included in the scope of the present invention.

Further, in this case, the program code itself of the software realizes the function of the above-described embodiment, and the program code itself and a means for supplying the program code to the computer,
For example, a storage medium storing such program code constitutes the present invention. As a storage medium for storing the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-RO.
M, a magnetic tape, a non-volatile memory card, a ROM, or the like can be used.

Further, the computer executes the supplied program code so that not only the functions described in the above embodiments are realized, but also the OS (operating system) in which the program code is operating in the computer. Needless to say, the program code is also included in the embodiments of the present invention when the functions shown in the above embodiments are implemented jointly by other application software or the like.

Furthermore, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the function expansion board or function expansion unit is instructed based on the instruction of the program code. The present invention also includes a case where the CPU or the like included in the above performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

[0042]

According to the present invention, since it is possible to operate the mechanical shutter without causing a luminance step regardless of the set electronic shutter speed, it is possible to control the interline distance without limiting the electronic shutter. It is possible to prevent the luminance step from occurring.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an image pickup apparatus of the present invention and showing a circuit configuration example of the image pickup apparatus.

FIG. 2 is a diagram showing a timing of a still image shooting operation according to the embodiment when a high-speed electronic shutter is set.

FIG. 3 is a control flowchart of a camera control unit according to the present embodiment.

FIG. 4 is a diagram showing a timing of a conventional still image shooting operation.

FIG. 5 is a diagram showing a conventional example in which a high-speed electronic shutter is set and a timing of a still image shooting operation.

[Explanation of symbols] 101 lens 102 aperture 103 image sensor 104 CDS / AGC 105 A / D converter 106 camera signal processing unit 107 image recording unit 108 memory 109 camera control unit 110 Timing Generator (TG)

Claims (5)

[Claims] 1. An image pickup apparatus having a mechanical shutter and an electronic shutter, wherein if the electronic shutter is set to an exposure time shorter than a time until the mechanical shutter is fully closed, the mechanical shutter is fully closed. Until the operation is completed, exposure is continued in the state of waiting for reading, and the video signal of the odd field and the video signal of the even field are read in order from the next field after the field waiting for the reading is finished. An imaging device characterized by the above. 2. An image pickup apparatus, comprising a mechanical shutter and an electronic shutter, for performing frame reading using an interlace readable image pickup element, comprising: a mechanical shutter for interrupting exposure of the image pickup element by a diaphragm; The mechanical shutter operation control means for controlling the operation of the mechanical shutter and the electronic shutter speed control means capable of electrically controlling the exposure time of the image pickup device are provided, and the exposure time of the electronic shutter is controlled by the mechanical shutter operation control means. If the exposure time is set faster than the operable exposure time of, the frame reading is performed in order of the video signal of the odd field and the video signal of the even field after performing the accumulation operation over a plurality of fields. An imaging device characterized in that 3. An image pickup method using an image pickup device having a mechanical shutter and an electronic shutter, wherein if the electronic shutter is set to an exposure time shorter than a time until the mechanical shutter is fully closed, Until the mechanical shutter fully-closed operation is completed, the exposure is continued in the state of waiting for reading, and the video signal of the odd field and the video signal of the even field are read in order from the next field after the field waiting for the reading is completed. The image pickup method is characterized in that 4. A computer-readable storage medium on which a program for causing a computer to execute the method according to claim 3 is recorded. 5. A computer program that causes a computer to execute the method according to claim 3.