JP2552500B2 - Imaging device - Google Patents

Description

The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus capable of selectively switching between a field image pickup method and a frame image pickup method.

[Prior Art] In an imaging device capable of telephoto shooting using a zoom lens or an interchangeable lens, if the focal length of the lens is increased,
Shake easily occurs. Especially when the imaging time is not short, this camera shake is more likely to occur.

In order to prevent such camera shake, the conventional film camera has solved the problem by releasing the shutter at high speed to shorten the exposure time.

However, in a solid-state image sensor or an image pickup tube using a CCD or a MOS, the sensitivity is not so high that the shutter is released at a very high speed, so that it is more difficult to prevent camera shake than a film camera.

In addition, when shooting a low-luminance subject during indoor shooting and the like, insufficient sensitivity is likely to occur due to low sensitivity.

Thus, in the case of underexposure, it is necessary to take measures such as switching to stroboscopic photography to compensate for the underexposure.

[Problems to be Solved by the Invention] As described above, in the conventional image pickup apparatus, when shooting is performed by using the light emitting means such as a strobe, the exposure is changed due to the switching of the field / frame image pickup method in the image pickup means. There was a problem.

In view of these problems, it is an object of the present invention to provide an image pickup apparatus capable of taking an image with the exposure deviation suppressed as much as possible even when taking an image of a low-luminance subject using a light emitting means. .

[Means for Solving the Problems] In order to achieve this object, according to the present invention, an image pickup unit having a plurality of pixels arranged in rows and columns to form an image signal, and each row from the image pickup unit. The first mode in which the first image signal having low sensitivity and high resolution is formed by reading out without adding the signal of No. 1 and the high sensitivity and low resolution by adding and reading a plurality of rows from the imaging unit. Switching means for switching between a second mode for forming a second image signal, flashing means for irradiating a subject with flashing light, dimming means for performing a dimming operation by the flashing means, and the dimming means Detection means for detecting that the light emission time of the flash means is longer than a predetermined time after performing the image pickup operation in the image pickup means while performing the light control operation,
When the detection means detects that the light emission time of the flash means is longer than the predetermined time, it controls to read out the signal in the second mode from the image pickup means after the end of the image pickup, and still the light amount If there is a shortage, the control means further increases the gain of the signal from the image pickup means.

[Operation] According to the present invention, since the sensitivity of the image pickup device is different by selecting either the field image pickup method or the frame image pickup method when the issuing means is used, the distance and diaphragm programs are shifted by one step. By shifting the light emission amount, proper exposure can be performed in either mode, and even if the photometric value of subject brightness is low, it is possible to compensate for underexposure and also optimize exposure.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of an embodiment of an image pickup apparatus according to the present invention, and FIG. 2 is a diagram showing an example of a basic structure of a CCD image sensor used in the embodiment. In this figure, 1 is an optical system for forming a subject image, 2 is a diaphragm,
3 is a beam splitter, 4 is a shutter, 5 is a CCD image sensor, 6 is a signal processing circuit, 7 is a recording unit for recording the signal processing result on a magnetic medium, 8 is a focus adjusting unit, 9 is a photometric circuit, and 10 is control. A circuit, 11 is a display for displaying control results, 12 is a stroboscopic light emitting part, 21 is a vertical CCD shift register of each CCD image sensor 5, 22 is a horizontal CCD shift register, 23 is a buffer amplifier, and 24 is a photo diode. It is a sensor unit showing a basic configuration of a sensor including a photoelectric conversion unit and a transfer gate.

The beam splitter 3 is for dividing incident light from a subject into an imaging system including a CCD image sensor 5 and a photometric system including a photometric circuit 9.

The control circuit 10 has functions such as detecting the subject brightness from the photometric circuit 9 through the line a and calculating the shutter speed and aperture value. Depending on the calculation result, the line b
While controlling the aperture 2 and shutter 4 through c and c,
The CCD image sensor 5 is controlled through the line d to switch the field imaging method or the frame imaging method. The sensitivity is switched by adjusting the gain of the signal in the signal processing circuit 6 through the line e. Further, the control result and the like are displayed on the display device 11 through the line f, and the focus adjusting unit 8 and the stroboscopic light emitting unit 12 are controlled through the line g, the lines h and i. Strobe flash unit 12
With respect to the control, the line h is used to output whether the strobe is mounted or not mounted, whether charging is completed when the strobe is mounted, or whether or not the strobe can be used due to incompletion, and the strobe emission time is controlled through the line i. Further, it also has functions such as control of various timings necessary for the image pickup recording device, and detection of release and other switching states of switches.

The CCD image sensor 5 of FIG. 2 operates as follows. The signal charge accumulated in each sensor section 24 is selectively applied to each vertical CCD shift register 21 according to the presence / absence of a pulse externally applied to the transfer gate during the vertical blanking period.
And then to the horizontal CCD shift register 22 by one row for each horizontal blanking period.

Then, the signals are sequentially output from the buffer amplifier 23 to the outside through the horizontal CCD shift register 22 during the horizontal video period.

Here, at the time of frame imaging, light is shielded after full-screen exposure,
During the subsequent vertical blanking period, odd rows A ₁ , A ₂ , A ₃
The signal charges in ... Are first selected by the transfer gate, transferred to each vertical CCD shift register 21, and then sequentially transferred to the horizontal CCD shift register 22 row by row during each horizontal blanking period. _{Then, ‥‥‥ A 3, A 2,} A 1 of the signal of every other row in each horizontal scanning period are successively read as the first field signal. In the vertical blanking period after this reading, the signal charges in the even rows B ₁ , B ₂ , B ₃ ... are selected and taken into the vertical shift register, and then read every horizontal operation period. .. are sequentially read as the second field signal in the order of B ₃ , B ₂ , and B ₁ .

On the other hand, at the time of field imaging, after accumulating for a predetermined period, in the vertical blanking period immediately before the start of reading in the first field period, odd-numbered rows A ₁ , A ₂ , A ₃
The signal charges of both rows B ₁ , B ₂ , B ₃ ... are simultaneously selected by the transfer gates and taken into each vertical CCD shift register 21, and then added one pair at a time during the transfer to obtain the horizontal return. One line is transferred to the horizontal CCD shift register 22 for each line period. Hereinafter, ‥‥‥ A ₃ each horizontal scanning period +
The added signals such as B ₃ , A ₂ + B ₂ , A ₁ + B ₁ are sequentially read. In addition, during the first field period, each sensor unit 24
The signal stored in is read out in the second field period. In this case, the combination of the two rows to be added is B ₁ + A ₂ , B ₂ + A.
₃ Change as follows, and read in the same way.

As described above, in the field imaging mode, the transfer charge amount in each transfer cycle is double that in the frame imaging mode. Therefore, in field imaging, the vertical resolution is halved compared to frame imaging, but the sensitivity is 2
It is doubled.

Next, the operation of the control circuit 10 will be described with reference to the flowchart of FIG.

After the power is turned on, it is activated by turning on a release button (not shown). First, at step (1), the control circuit 10 opens the shutter 4 through the line c. In step (2), the control circuit 10 turns on the strobe light emitting section 12 through the line i to start strobe light emission. Simultaneously with the strobe light emission, in step (3), the photometry circuit 9 starts photometry of the subject brightness. The photometric value (the integrated value of the amount of received light) from the photometric circuit 9 is output to the control circuit 10 through the line a. In step (4), the photometric value L ₁ input to the control circuit 10 is compared with a preset proper light amount value L _0, and the control circuit 10 determines whether or not the light amount is sufficient.

If the light quantity is already sufficient (L ₁ ≧ L ₀ ), the photometric value L ₁ at that time is held, and in step (5), the strobe light emitting section 12 is turned off from the control circuit 10 through the line i. , Stop firing the flash. Also, step (4)
If the light intensity is insufficient (L ₁ <L ₀ ), a certain time T ₀
Within the range, step (4) and step (6)
The above procedure is repeated, and the flash emission is stopped when the light intensity becomes sufficient or when T ₀ is reached. Further, the photometric value L ₁ up to that point is held. The fixed time T ₀ is the exposure time in normal strobe synchronization (for example, about 1/60 second).

Next, in step (7), the control circuit 10 causes the line c
Through to close the shutter 4.

In step (8), based on the photometric value L ₁ held up to the previous stage, the control circuit 10 again determines whether or not the amount of light is sufficient based on the reference value L ₀ ′. The reference value L ₀ ′ here is set to about 70% of the appropriate light amount value L ₀ . Light intensity value is almost sufficient (L ₁ ≧ L ₀ ′)
If so, the control circuit 1 reads the CCD image sensor 5
If the frame imaging mode (step (10)) is insufficient (L ₁ <L ₀ ′) through the line d by ₀ , the sensitivity is doubled as compared with the frame imaging mode (step (9)). )) Is automatically selected. According to each mode, in step (11) or (12), the display 11 informs the outside that each mode of frame imaging or field imaging is selected.

The video signal read by the CCD image sensor 5 passes through the signal processing circuit 6 and is recorded on the recording medium of the recording unit 7 at an appropriate timing in step (13).

FIG. 4 is a flow chart for explaining the second embodiment. The first half is the same as that in FIG. 3, so (A)
Omitted before.

In step (14), exactly the same as step (8) in the first embodiment, when the light quantity is sufficient, the video signal passing through the signal processing circuit 6 is processed with a gain set in advance, It is recorded in the recording medium of the recording unit 7 at (17). When the amount of light is insufficient, the control circuit 10 adjusts the gain of the video signal passing through the signal processing circuit 6 through the line e to an appropriate level, and notifies the display 11 to the outside in step (16). At the same time, the data is recorded on the recording medium of the recording unit 7 in step (17).

FIG. 5 is a flow chart for explaining the third embodiment. The first half is the same as that in FIG. 3, so (A)
Omitted before.

The other operations except the steps (23), (24) and (25) are exactly the same as the operations after (A ₁ ) in FIG. That is, when the amount of light is sufficient in step (18), the frame image pickup mode is selected in step (20) and the frame image pickup mode is selected in step (22).
After displaying in 11, step through the signal processing circuit 6 with the gain of the signal processing circuit 6 fixed to the initial setting value (26).
Is recorded on the recording medium of the recording unit 7.

If the amount of light is insufficient, select the field imaging mode in step (19), display that fact on the display unit 11 in step (21), and then check in step (23) again whether the amount of light is sufficient. The control circuit 10 determines whether or not it is. The light amount in this step is determined in consideration of the sensitized amount due to the switching to the field imaging mode, and the appropriate light amount value L ₀ for the value 2L _{1 obtained} by doubling the photometric value L ₁ held in the previous stage (before (A)). Compare with.

When the amount of light is sufficient (2L ₁ ≧ L ₀ ), the signal processing circuit 6
The gain is fixed to the initial setting value and is recorded on the recording medium of the recording unit 7 through the signal processing circuit 6 in step (26).

When the amount of light is insufficient (2L ₁ <L ₀ ), the control circuit 10 adjusts the gain of the video signal passing through the signal processing circuit 6 through the line e to an appropriate level, and the step (2
At step 5), the display 11 is notified to the outside, and at step 26, it is recorded on the recording medium of the recording section 7.

In the above embodiment, as the means for detecting the brightness of the subject, the photometric circuit 9 for capturing the light by the beam splitter is provided separately from the video signal processing system. However, among the outputs of the CCD image sensor 5, particularly the brightness component is detected. For example, the subject brightness may be detected by smoothing.

Further, in the above embodiments, only the case of strobe light control has been described, but it is clear that the operation when strobe light control is not performed is performed in the same manner.

FIG. 6 is a diagram showing the outline of another embodiment of the image pickup apparatus according to the present invention. Since the apparatus of FIG. 6 has almost the same configuration as the apparatus of FIG. 1, only the points different from FIG. 1 will be described below. In the figure, 13 is a frame / field switching operation section, which is input to the terminal j of the control circuit 10. Reference numeral 14 denotes a switching operation unit for switching between daytime light (hereinafter referred to as AE) shooting and strobe (hereinafter referred to as EF) shooting, which is input to a terminal k of the control circuit 10. The control circuit 10 can also control the state of the photometric circuit 9 via the terminal a '.

The above is the characteristic of the configuration in this embodiment, and
In particular, the operation at the time of EF photography will be described with reference to FIGS. 7 and 8 for the case where the strobe 12 is always made to emit full light. The light quantity of the strobe is 16 m for the field system and 11 m for the frame system in the guide number display.
(Since the field method and the frame method have different sensitivities, there will be a difference in guide number).

FIG. 7 is a flowchart showing an example of the operation of this embodiment, and FIG. 8 is a diagram showing the relationship between FNo and distance D.
Power supply (switch) not shown in step (101) of FIG.
When is turned on, the control circuit 10 determines the state of the AE / EF switching operation section 14 from the terminal k. In step (101), EF
If not, AE photography is performed by controlling the aperture according to the output of the photometry circuit 9. If the EF photographing is performed in step (101), the process proceeds to the next step (102), and the control circuit 10 determines the state of the terminal j and the state of the frame / field method switching operation unit 13. In the case of the field method in step (102), since the field method guide number is 16 m as already described, the guide number variable G is set to 16 in step (103).
And As a result of the step (102), in the case of the frame method, since the guide number is 11m as already described, the guide number variable G is set to 11 in the step (104). Next, in step (105), focusing is performed via the focus adjustment unit 8 and the distance D to the subject is obtained. Then, the aperture value FNo = G / D (1) at which the appropriate amount of light is obtained at the distance D is calculated (step (106)).

In the equation (1), if the frame imaging method is used, G
= 11, G = 16 in the field imaging method, so F
The relationship between No and the distance D is as shown in FIG. 8A (for the field method) and B (for the frame method).

Next, in step (107), it is determined whether or not a release member (not shown) has been operated, and if the release member has not been operated, the process returns to the initial stage.

If the release member is operated in step (107), the control circuit 10 determines the terminal b in step (108).
The aperture 2 is narrowed down to the value of the expression (1) via. Next, in step (109), the control circuit 10 opens the shutter 4 via the terminal c, and then in step (110) causes the strobe 12 to fully emit light via the terminal i. Then step (111)
The shutter 4 is closed at, and recording is performed in the same manner as in the other embodiments at step (112) as already described above.

As is clear from the above description, in the present embodiment, the sensitivity of the image pickup element is doubled in the field and the frame, which results in the difference in the guide number. Therefore, as shown in FIGS. By shifting the program by one stage, proper exposure is performed in either mode.

Next, one modification of the embodiment described with reference to FIGS. 6 to 8 will be described with reference to FIGS. 9 and 10.

FIG. 9 is a flow chart showing the operation of a modified example of this embodiment, and since it is almost the same as FIG. 7, only different points will be explained. That is, after the field / frame method is determined in step (102), in the case of the field method, the strobe 12 is made to illuminate with a half of the total light emission. Because in the case of the field method, the guide number was 16 m because of the high sensitivity, but the guide number when illuminating this with half the light amount is The strobe 12 is the same as the frame system guide number when all flashes are emitted, and the step (106) is FNo = 11 / D (m) ... (3) for both the frame system and the field system. The control is performed according to the curve B.

Here, means for causing the strobe to emit half the total amount of light is shown in FIGS. 10 (a) and 10 (b).

The strobe shown in FIG. 10 (a) includes a charging circuit 201, main capacitors 202 and 203 divided into equal capacitances, a switch 204, a trigger circuit 205, a flash discharge tube 206 connected in series to the main capacitor 202. Consists of.

The control circuit so that the switch 204 is turned on in the frame system and turned off in the field system at the next point after determining the frame system or the field system in FIG. 10 (a).
Controlled by switch 10 (this particular configuration is switch 204
Can be easily realized by configuring a relay etc.). Therefore,
Charging and light emission are performed using only the main capacitor 203 in the field method and both main capacitors 202 and 203 in the frame method. In the case of the field method, since only the main capacitor 203 is used as compared with the frame method, the capacity is halved, so the amount of light emission is also halved.
Function 3) is realized.

Next, in the case of FIG. 10 (b), the configuration is similar to that of FIG. 10 (a), and therefore only different points will be described. In FIG. 10 (b), it is assumed that one main capacitor 203 has a combined capacity of the capacitors 202 and 203 in FIG. 10 (a). Further, a light quantity control circuit 207 is connected in series with the flash discharge tube 206. In this light amount control circuit 207, it is assumed that when the control terminal 1 is at a high level, the terminals mn are conducted, and when the control terminal 1 is at a low level, the terminals mn are not conducted.
In FIG. 10 (B), in the case of emitting the total amount of light, the terminal l of the light amount control circuit 207 may be set to the high level for a sufficiently long time with respect to the total amount of light emission time, and the terminals mn may be electrically connected. When light is emitted at 1/2 light intensity, the terminal l of the light intensity control circuit 207, which has once been set to the high level at a timing corresponding to 1/2 of the total light emission amount, is set to the low level again and the terminals m-n
It suffices to make the spaces non-conductive.

Of course, the strobe used in the above-mentioned embodiment can be built in the main body of the image pickup apparatus or attached to the outside of the main body. Further, a dimming type may be used in addition to the full emission as in the embodiment. In that case, it goes without saying that the light emission amount can be changed depending on the light emission time.

[Effects of the Invention] As is apparent from the above description, according to the present invention, proper exposure is obtained by changing the aperture or the light emission amount according to whether the field imaging method or the frame imaging method is selected. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an embodiment of an image pickup device according to the present invention, FIG. 2 is a diagram showing an example of a basic structure of a CCD image sensor used in the embodiment, FIGS. 3, 4, and FIG. 5 is a flow chart for explaining the operation of the control circuit in the first, second and third embodiments, respectively.
FIG. 7 is a diagram showing the outline of another embodiment of the image pickup apparatus according to the present invention, FIG. 7 is a flow chart showing an example of the operation of this embodiment, FIG. 8 is a diagram showing the relationship between distance and aperture, and FIG. FIG. 10 is a flowchart showing the operation of a modified example of this embodiment, and FIG. 10 is a strobe charging circuit diagram in an embodiment of the present invention. In the figure. 1: Optical system, 2: Aperture 3: Beam splitter 4: Shutter 5: CCD image sensor 6: Signal processing circuit, 7: Recording section 9: Photometric circuit, 10: Control circuit 11: Display, 12: Strobe light emitting section 13 : Frame / field switching operation part 14: AE / EF switching operation part

Claims (1)

(57) [Claims] 1. An image pickup means having a plurality of pixels arranged in rows and columns to form an image signal, and a low sensitivity and high resolution by reading out signals of each row from the image pickup means without adding them. Switching means for switching between a first mode for forming one image signal and a second mode for forming a second image signal having high sensitivity and low resolution by adding and reading a plurality of rows from the image pickup means. A flashing means for irradiating the subject with a flashing light, a dimming means for performing a dimming operation by the flashing means, and an imaging operation in the imaging means while performing a dimming operation by the dimming means. When detecting that the light emission time of the flash means is longer than a predetermined time, and if the detection means detects that the light emission time of the flash means is longer than the predetermined time, first, Control for reading out a signal from the image pickup means in the second mode after the image is finished, and further increasing the gain of the signal from the image pickup means when the light quantity is still insufficient. A characteristic imaging device.