JP2552499B2 - 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 and shortening 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 photographing apparatus, when photographing 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 by suppressing exposure deviation as much as possible even when shooting a low-luminance subject.

[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 unit detects that the light emission time of the flash unit is longer than the predetermined time, a control unit that controls to read a signal from the image pickup unit in the second mode after the image pickup is completed. I have.

[Operation] According to the present invention, since the photometric characteristic of the subject brightness is changed depending on the field image pickup method and the frame image pickup method, exposure deviation does not occur at the time of dimming strobe photography.

[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. Circuit, 11 is a display for displaying control results, 12 is a stroboscopic light emitting part, 21 is a vertical CCD shift register group of the CCD image sensor 5, 22 is a horizontal CCD shift register, 23 is a buffer amplifier, 24 is a photo diode 2 is a sensor section showing a basic configuration of a sensor including a photoelectric conversion section 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 and the photometry circuit 9 have functions such as detecting the subject brightness through the line a and calculating the shutter speed and aperture value. In accordance with the result of this calculation, the aperture 2 and the shutter 4 are controlled through the lines b and c, and 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. Also,
The control result and the like are displayed on the display 11 through the line f, and the focus adjustment unit 8 is also displayed through the line g and the lines h and i.
And controls the flash emission unit 12. Regarding the control of the strobe light emitting section 12, the strobe light emission time is controlled through the line i by outputting whether the strobe is attached or not attached, the charging completion or not when the strobe is attached, and whether or not the strobe can be used. 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 within 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, in 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 switching to the field imaging mode, and the appropriate light amount value L for the value 2L _{1 obtained} by doubling the photometric value L ₁ held in the previous stage (before (A)). Compare with ₀ .

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 will be apparent 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 method and 11 m for the frame method 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 it is not photographing, aperture control is performed according to the output of the photometric 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 16m as already described, the guide number variable G is set to 16 in step (103). 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). Then step (105)
Then, the focus is adjusted via the focus adjustment unit 8 and the distance D to the subject is obtained. And that distance D
Calculate the aperture value FNo = G / D (1) that gives the appropriate light amount at (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.

Further, as still another embodiment, an example in which the present invention is applied to a case in which the diaphragm is determined according to the subject distance and the strobe emission is stopped when the reflected light from the subject corresponding to the diaphragm is obtained is shown. . The structure of this embodiment may be the same as that shown in FIG.

FIG. 11 is a flow chart showing an example of the operation of this embodiment. Since Fig. 11 is almost the same as Fig. 7,
Only the different points will be described. In FIG. 11, after the frame / field method is discriminated in step (102), in step (103), in the case of the field method, the integral condenser capacity of the strobe light metering circuit is set to a specified value,
When determining the aperture in the subsequent step (106), the aperture is determined according to the program diagram A in FIG. 13, and in step (104), if the frame method is used, the integral condenser capacity of the strobe light metering circuit is twice the specified value. Set to
In determining the aperture in the subsequent step (106), the aperture is determined according to the program diagram B in FIG. The switching of the integration capacitor capacity described here will be described using the circuit of FIG.

FIG. 12 is a diagram showing a configuration example of the photometric circuit 9. In FIG. 12, 301 is an operational amplifier having an extremely high input impedance, p is a non-inverting input, q is an inverting input, and o is an output. 302 is a light receiving element, and 303 and 304 are capacitors having the same capacitance. The integrated values of the amount of reflected light received from the subject are obtained by these capacitors 303 and 304. Reference numeral 305 denotes a switch circuit, which is electrically connected between the terminals s and t when the control terminal r is at a high level and electrically disconnected between the terminals s and t when the control terminal r is at a low level.

In the circuit of FIG. 12, the control terminal r of the switch circuit 305 is connected to the control circuit 10, and after the field / frame method is determined, if the field method is used, the switch circuit 305 is used.
The control terminal r of is set to the low level and the control terminal r of the switch circuit 305 is set to the high level in the case of the frame method so that the exposure amount of the image pickup device 4 is doubled in the case of the frame method in the field method. You can control. Although the capacitance of the integrating capacitor is doubled here, it goes without saying that the value of the integration result may be halved.

There are various possible methods for determining the aperture in step (106) of FIG. 11, but in the case of the field method, the aperture is determined according to the program of FIG. 13, and in the case of the frame method, according to FIG. One example is determining the aperture. In this case, for example, even if the field / frame method switching operation member 13 is the frame method, if the distance to the subject is 5.5 m or more according to the distance measurement result, the frame method cannot be used for shooting, and the field method can be used for shooting. The photograph is taken by the method, and the photographer is informed using the display means 11 shown in FIG. Also, if the field method program diagram is executed by the program shown in FIG. 14 which is the same as the frame method, the flash output will be large, but since it takes half the charging time of the field method, continuous shooting is possible. The charging time can be shortened.

Further, as shown in FIG. 15, it is possible to program the frame system (B) at the near point and the field system (A) at the far point in the object distance zone.

Further, as shown in FIG. 16, even if the zone division is the same, the aperture value can be changed between the frame method and the field method.

In this example, the photometric circuit 9 in FIG.
If this is done, there is no need to switch the mode for the photometric circuit 9 by the field / frame method as shown in FIG. 12, so the circuit system becomes simple.

It is needless to say that it can be incorporated in the main body of the stroboscopic imaging device used in the above-mentioned embodiment or can be attached to the outside of the main body. The exposure amount may be controlled by a shutter in addition to the diaphragm.

[Effects of the Invention] As described in detail above, according to the present invention, the dimming emission amount can be set to an appropriate value according to the selection of the frame imaging method and the field imaging method.

[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. 10 is a flow chart showing the operation of a modified example of the present embodiment, FIG. 10 is a strobe charging circuit diagram in the embodiment of the present invention, FIG. 11 is a flow chart showing an example of the operation of this embodiment, and FIG. Switching circuit diagram, Fig. 13, Fig. 14,
15 and 16 are diagrams showing the relationship between the distance and the aperture in each imaging method. In the figure. 1: Optical system 2: Aperture 3: Beam splitter 4: Shutter 5: CCD image sensor 6: Signal processing circuit 7: Recording unit 9: Photometric circuit 10: Control circuit 11: Display unit 12: Strobe light emitting unit 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. A detecting means for detecting that the light emitting time of the flash means is longer than a predetermined time; and an image pickup when the detecting means detects that the light emitting time of the flash means is longer than the predetermined time. Imaging device comprising control means for controlling so as to read out signal in said second mode from said image pickup means to After the completion, to have a.