JPS63240183A - Image pickup device - Google Patents

Abstract

PURPOSE:To preclude underexposure and a hand-shake phenomenon by controlling sensitivity variation including field/frame image pickup mode switching and a shutter time according to the focal length of an optical system and the brightness of an object. CONSTITUTION:A control circuit 10 detects the object brightness by a light measuring circuit 9 through a line (b) to calculate shutter speed and an aperture value. A stop 2 and a shutter 4 are controlled through lines (a) and (c) according to the arithmetic result and the focal length of the optical system 0 and the photographic mode of a CCD image sensor 5 is switched between a field and a frame mode through a line (d). Further, the gain of a signal processing circuit 6 is switched through a line (e) and a signal from the CCD 5 is sent to a recording part 7. Further, the control part 10 displays a control result, etc., on a display device 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an imaging device, and particularly to an imaging device having a field/frame mode switching imaging function.

(Prior Art) For example, in an imaging device having a telephoto shooting function using a zoom lens, an interchangeable lens, etc., when the focal length of the lens is increased, "shaking" during shooting tends to occur as is well known. In particular, this tendency increases even more when the imaging time is relatively long.

Therefore, in order to prevent these camera shakes, conventional film cameras and the like solve this problem by shortening the exposure time by using a high-sensitivity film and increasing the shutter speed.

However, COD (charge coupled device) and MOS
In electronic imaging devices that use solid-state image sensors (metal oxide layer semiconductor) or image pickup tubes, etc., the original sensitivity is not high enough to release the shutter quickly enough to prevent f-shake. . Further, even if not particularly in telephoto shooting, for example when shooting indoors, underexposure is extremely likely to occur for a subject with low brightness due to the low F2 sensitivity.

[Problems to be solved by the invention] Therefore, when there is insufficient light, it is necessary to switch to strobe photography as in the case of film cameras, or
After imaging, in the subsequent signal processing process, the SN of the video signal is
Even in exchange for the corresponding deterioration in the ratio, it was necessary to take measures such as increasing the signal gain by -F to compensate for the lack of exposure.

The present invention is based on the conventional technology of fixed image sensors, image pickup tubes, etc. as described above, and aims to prevent underexposure of subjects in a wide brightness range as much as possible in an imaging device capable of capturing images in both field and frame formats, and to reduce camera shake. The purpose of the present invention is to provide an imaging means that can take images without causing phenomena.

[Means for solving problems]

For this reason, the present invention improves sensitivity, including field/frame imaging mode switching, and increases aperture value/shutter time in accordance with the focal length of the optical system, the brightness of the subject, and the charging completion signal of the strobe light emitting means. The purpose of the present invention is to achieve the above object by configuring the system to automatically control the process.

[Operation] With the above configuration, depending on the shooting conditions at the time,
Since sensitivity, shutter speed, etc. are optimally and automatically controlled within the functional limits of the device, the possibility of image deterioration due to manual digging can be reduced.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a configuration block diagram of an embodiment of an imaging device according to the present invention.

(Configuration) 0 is an optical system for forming a subject image, l is an imaging lens, 2 is an aperture, and 3 is a CCD that converts incident light from the subject.
a beam splitter for dividing into an imaging system including the image sensor 5 and a measurement system including the measurement circuit 9; 4 is a shutter;
6 is a video signal processing circuit, 7 is a recording unit for video information on a recording medium, and 8 is a focus adjustment unit for the imaging lens 1. In the imaging apparatus of this embodiment, for the purpose of simplifying the explanation, an optical As an example of the purest configuration, system O uses a zoom lens l having only two focal lengths, wide-angle and telephoto. , a signal that is turned on during telephoto mode is output to the control circuit 10 through line g. However, in this case, even if a zoom lens with a continuously variable focal length magnification is used, it does not have the function to output information on whether it is on the wide-angle side or the telephoto side depending on the focal length through the line g. That's fine.

The control circuit 10 detects the subject brightness from the measurement circuit 9 through line b, for example, and calculates the shutter speed TV and aperture value Av, which are determining factors of the 4M shadow time.

Also, according to the calculation results, the aperture 2 and shutter 4 are controlled through each line a and c, respectively, and
Each line d, e.

Through f, switching of the field/frame imaging mode, switching of the gain of the video signal system, etc. are performed.

In the recording unit 7, the result of the No. 13 processing is recorded in a memory, a magnetic medium, etc., and the control result etc. are displayed on the display 11.

The control circuit 10 is configured to control various timings necessary for the image capturing and recording apparatus, detect release and other switching states of switches, and the like.

(Operation) Next, the operation in the above configuration will be explained based on the operation sequence flowchart shown in FIG.

After the power supply of the imaging device is completed, in step S1, the state of an external changeover switch (not shown) for setting the field/frame imaging mode is detected, and the control circuit 10 accordingly changes the state of the CCD image sensor 5 through the line d. Set the imaging mode to either field or frame.

Here, prior to explaining the overall operation of the apparatus, the operation of the CCD image sensor 5 corresponding to each field/frame mode will be briefly explained. FIG. 3 shows an example of a basic configuration diagram of a CCD image sensor 5 that can be used in this embodiment.

In the figure, 13V is the vertical CCD shift register details, 1
3. , J is a horizontal CCD shift register, and each unit cell of each sensor section 15 is composed of a photoelectric conversion section consisting of a photodiode and a transfer gate, as shown inside the dotted line.

The video signal charge accumulated in each sensor section 15 is selectively transferred to the horizontal CCD shift register 13N through each vertical CCD shift register 13V during the retrace period depending on the presence or absence of a pulse applied to the transfer gate from the outside. be taken in. Then, during the horizontal scanning period, the water shift register!
3.1, the buffer 14 sequentially outputs the data to the outside.

Here, differences in the transfer process between the field and frame imaging modes will be explained.

(1) First, in the frame imaging mode, in the first field period, signal charges for one horizontal row indicated by the first row F AI in FIG. 3 are first selected by the transfer gate, and each vertical shift register 13v, and the water KP: is transferred to the horizontal shift register i3■ during the retrace period. After that, A2. Rows are selected and read out in the order of A3.

Next, in the second field period, data for one horizontal row indicated by B1 is selected, and thereafter, 82. Rows are selected in the order B3 and exited.

(2) On the other hand, in the field layer image mode, in the first field period, first, the uppermost RA1 and the second
The signal charges of both rows of row B1 are transferred to each vertical shift register 13. by the transfer gate. The data is transferred to the horizontal shift register 13□ within the horizontal #M period. After that, A2+82. In the order of A3+83,
Two lines are read out at once.

Next, in the second field period, the combination of the two rows to be selected is changed, and B1+A2. They are read out in the order B2+A3 in the same way as the first field.

Therefore, due to the difference in the transfer process between each field/frame mode as described above, in the frame imaging mode, in the field imaging mode, ! The amount of charge transferred within the register per transfer cycle is doubled, and as a result, the sensitivity is 62 times higher during field imaging than during frame imaging.

Next, returning to the flowchart in FIG. 2, the explanation of the operation will be continued.

In step S2, the measuring circuit 9 (FIG. 1) is activated and the subject brightness is input to the control circuit 10 through line b. Then, in step S3, the control circuit 10 calculates the optimum aperture value A and shutter speed TV based on the subject brightness. Next, in step S4, the control circuit 10 determines whether it is the wide-angle side or the telephoto side from the focal length of the imaging lens 1 through the line g, and if it is the wide-angle side (g line off), the control circuit 10 jumps to step 520 and releases the camera. have.

In this case, the field/frame imaging mode remains as it was previously set in step S1,
Since the sensitivity is not corrected by increasing the gain of the video signal system, the SN ratio of the image information is not degraded.

In step S4, if it is determined that it is on the telephoto side, in step S5, the shutter speed Tν
is equal to or higher than the camera shake limit speed Tv0.

If T v 2 T vo, the process directly jumps to step S20 and waits for release.

On the other hand, if Tv<Tvo, further, in step S6, it is checked whether the imaging mode of the COD urea sensor set in step S1 is field or frame, and if it is already in field imaging mode, , m Since the sensitivity cannot be expected to be increased by converting the shadow mode, the process skips steps S7, 38 and 39, and moves to step 311.

Correction When the imaging mode is the frame mode in step S6, the control circuit 10
As a result, the imaging mode of the COD image sensor 5 is forcibly switched to the field mode through the line d, the sensitivity of the video signal is doubled, and the set Tv value is increased by one level in step S8.

In this state, it is determined again in step S9 whether the shutter speed TV value has exceeded the camera shake limit speed Tvo, and if Tv≧Tv0, the initial imaging mode setting condition was frame. However, in step SIO, the control circuit 10 controls the display 1 by moving the line f@.
1 to notify the outside, and the process moves to step S16 to wait for release.

On the other hand, if in step S9, T
If v < T vo, or if it has already been determined in step S6 that the field imaging mode is set, then in step S11, the control circuit 1O causes the signal processing circuit 6 to transmit the image through the line e. The gain of the signal system is increased to double the sensitivity, and the shutter speed T is increased in step S12.
Level up V by one level.

Next, in step S13, it is determined again whether TV≧Tvo, and if TV≧TV. If,
By increasing the sensitivity, it is possible to take pictures without camera shake, although the image quality is degraded accordingly, and in step 5A14, the control circuit 10 drives the line f and reports this to the outside through the display 311. Step S1
6. Waiting for release. Here still T v < T
If it is vo, there is a possibility that camera shake will occur, so a camera shake warning is issued on the display 11 in step 315, and the process moves to step S16.

After that, in step S16, when it is detected that the release button (not shown) has been pressed, the control circuit 10 drives the aperture 2 and shutter 4 according to the values of the aperture value AV and shutter speed TV, In step S17, the CCD line sensor 5 is exposed to light, and then, in step S18, the recording unit 7 records the image information of the subject on a magnetic recording medium or the like at an appropriate timing.

Thereafter, the series of operations of the present embodiment shown in FIG. 1 is completed.

(Other Examples) In addition, in the navigation example, in order to simplify the explanation,
Although only the case where the increase in sensitivity due to gain adjustment of the video information signal system is doubled has been described, a continuously variable sensitivity improvement means may be provided.

Regarding processing procedures during telephoto shooting, etc., for image stabilization, priority was given to increasing sensitivity by switching field/frame CCD imaging modes over increasing sensitivity by adjusting the gain of the signal processing system.
Of course, a configuration in which the latter is given priority over the r-user is also possible.

In addition, the imaging lens can be a zoom lens built into the imaging device, an interchangeable single focus lens, an interchangeable zoom lens, etc. In particular, in the case of an interchangeable lens, there is a It is sufficient to provide a mark and provide a detection member for detecting the mark on the imaging device side.

Furthermore, in the embodiment, the shutter speed is 1/T with respect to the exposure time T by the shutter 4.
= 2", and as an aperture value, F 2 = 2A for the F number speed.
Although the value AV expressed by the relationship of v is used, the present invention is not limited to this.

In addition, in order to detect the subject brightness, in this embodiment, a measuring circuit 9 including 1, for example, 5pc (setting production system 04) is separately installed, but the brightness component is particularly important among the output of the image sensor CCD 5. The brightness of the subject may be detected by smoothing the brightness of the subject.

〔Effect of the invention〕

As explained above, according to the present invention, the field/
In an imaging device having both frame imaging modes, the sensitivity change including switching between the two imaging modes and the shooting shutter time are controlled according to the focal length of the optical system, subject brightness, etc., so that images due to camera shake, etc. We were able to reduce the frequency of occurrence of deterioration.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram of an embodiment of an imaging device according to the present invention, FIG. 2 is an operation sequence flowchart thereof, and FIG. 3 is an example of a basic configuration diagram of a COD image sensor. 0...Optical system 1...Imaging lens 4--Shutter 5--COD image sensor 6--Signal processing circuit 8-- ---Focus adjustment section 9...-Measuring circuit 10-----i control circuit

Claims (1)

[Claims] An imaging device comprising an optical system that forms a subject image, and an imaging device that converts incident image information of the optical system into an electrical signal in both field and frame imaging modes, the imaging device comprising: a focal length of the optical system; Depending on the brightness of the subject,
An imaging apparatus characterized by comprising means for controlling at least one of a sensitivity change of the imaging means, including switching of the field/frame imaging mode, and a photographing shutter time element of the optical system.