JP2561264B2 - Imaging device - Google Patents

Description

The present invention relates to an image pickup device, and more particularly to an image pickup device having a light shielding means such as a shutter.

[Conventional technology]

Conventionally, when performing exposure control of an image pickup apparatus, since the latitude of the image pickup element used in the apparatus is very narrow, a highly accurate photometric circuit is required.

Therefore, a light receiving element dedicated to photometry is provided separately from the image sensor, and the light receiving state of the image sensor is once controlled based on the exit of the element by driving, for example, a shutter or diaphragm, and the image is captured under such control. A technique for taking out the output of an element and controlling it so that the light receiving state is readjusted again based on the output is known as, for example, Japanese Patent Laid-Open No. 59-194574.

[Problems to be Solved by the Invention] However, even when the conventional method is used, for example, when a normal person is photographed in the outside in the daytime, the output of the image pickup device is, for example, the light amount of a bright portion such as the sky. Since it is included in a large amount, it is dark depending on the person, and there is a problem that it is underexposed as a whole.

Such a problem has been a problem that can commonly occur in devices that process the output of the image sensor other than photometry. The present invention aims to solve such problems.

Another object of the present invention is to provide a novel light shielding method for an image sensor in view of the above problems.

Further, when the first exposure is performed based on the output of the light receiving element, if the shutter is actually driven according to the shutter time, the shutter structure becomes extremely complicated.

Therefore, in the first exposure, it is conceivable to electronically control the accumulation time instead of the shutter to perform imaging. However, in this case, the image pickup element accumulates for a short time at the high speed shutter speed, and smear and noise due to unnecessary light are often generated. Therefore, there is a problem that a large error is introduced into the output of the image pickup device obtained by the accumulation for a short time, and the correction operation of the photometry of the corner becomes meaningless, and the present invention aims to solve such a problem. I am trying.

[Means for solving problems]

In order to achieve the above-mentioned object, an image pickup apparatus according to a first aspect of the present invention includes an image pickup unit, a light receiving unit provided separately from the image pickup unit, and a second image pickup unit for the image pickup unit according to an output of the light receiving unit. A first mode in which the first exposure is performed and the second exposure is performed according to the signal formed in the image pickup means by the first exposure, and the first exposure is performed without performing the first exposure in accordance with the output of the light receiving means. Exposure control means having a second mode for performing two exposures.

An image pickup apparatus according to the second invention of the present application forms an exposure unit based on an output of the image pickup unit, a light receiving unit provided separately from the image pickup unit, and the first light receiving unit. The first exposure is performed on the image pickup means based on the exposure information, the second exposure is performed according to the signal formed on the image pickup means by the first exposure, and the output of the light receiving means is larger than a predetermined level. In this case, there is an exposure control means for making the aperture for the first exposure smaller than the aperture for the second exposure.

[Action]

According to the first invention of the present application, extremely accurate exposure control can be performed in the first mode by the first and second exposures, and a high-speed shutter time is required in which the first exposure is difficult. For example, by omitting the first exposure, the exposure control structure can be simplified. That is, if the first mode is to be realized under any subject condition, the exposure control structure becomes extremely complicated, but by adopting the second mode depending on the condition, the structure can be made extremely simple.

According to the second invention of the present application, extremely accurate exposure control can be performed by the first and second exposures, and when the subject is particularly bright, the aperture of the first exposure is made smaller than that of the second exposure. Therefore, the shutter time (accumulation time) of the first exposure can be made relatively long, and the structure for performing the first exposure can be simplified.

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

First, the mechanical configuration of the embodiment of the present invention will be described.

FIG. 1 is a perspective view of a diaphragm device and a shutter device according to an embodiment of the present invention. In FIG. 1, 1 is a CCD as an image pickup device, 2 is an optical axis, 3 is a diaphragm device, and 4 is a shutter device. The figure shows the initial state before photographing. That is, the light beam incident on the image sensor 1 along the optical axis 2 is a diaphragm plate.
By a part of the front blade 41 of the focal plane shutter, which is shielded by 30, and has a front blade 41 and a rear blade 51,
About 40% of the lower part of the image sensor 1 is shielded.

The rectangular diaphragm plate 30 has a groove 30M cut out in the longitudinal direction at the upper part, and the groove 30M has locking portions 30a to 30d and a slanted portion.
30e-30g are formed. In the lower part, the groove 30
On the straight line parallel to M, throttle holes 30B to 30D are formed at positions corresponding to the locking portions 30b to 30d, respectively. The diaphragm plate 30 is biased rightward (in the direction of arrow M) by a coil spring 30S that is hooked at the right end, and moves along a guide mechanism or the like (not shown). The diaphragm device will be further described with reference to FIG. FIG. 2 is a plan view of the diaphragm device. In the figure, 31 is a locking claw and the tip is a groove
A hook 31f that engages with 30M is formed, is rotatable about a shaft 31j, and is biased counterclockwise by a coil spring 31S.

32 is an L-shaped armature that has an L-shaped longitudinal section and has an outwardly bent hook portion 32f that is rotatable about a shaft 32j and is a leaf spring that abuts the yoke 33y of the magnet 33. 32b is welded and is urged clockwise by the leaf spring 32b. (See FIG. 2) Next, the shutter device 4 will be further described with reference to FIG. FIG. 3 is a front view showing a tightening release and displacement amount limiting device 40 for the leading blade 41, in which 41a and 41b are
A projection for controlling the position of the leading blade 41, which is a holding portion 41H of the blade 41.
It is provided in. 41S is a coil spring hooked on the holding portion 41H so as to apply rotational force to the leading blade 41 in the clockwise direction in the figure, and 44 is biased by the coil spring 44S so as to rotate in the clockwise direction about the shaft 44j. The locking member is provided with a hook portion 44f at its tip that locks to the protrusion 41a or 41b. Further, 54P is a stopper that restricts clockwise rotation of the locking member 44.

42 is an armature that has a substantially flat plate shape and is rotatable around a shaft 42j.
A plate spring 42b that abuts against 43y is welded, and is biased counterclockwise by the plate spring 42b.

Also, the tightening release and displacement amount control device for the rear blades 51.
The configuration of the front blade 41 is substantially the same as that of the front blade 41 except that the projection 41b is removed, and the rear blade 51, the coil spring 51S, the locking member 54, the coil spring 54S, the stopper 54P, and the armature.
52, a magnet 53, etc., and the locking member 54 and a part of the rear blade 51 are initially in a fully opened state, and when the magnet 53 is energized, the above engagement is released, and the rear blade is attached to a stopper (not shown). Rotates until they contact each other, and is in a fully closed state. (First
Next, the operation will be described.

First, when a release (not shown) is pressed, pre-exposure is performed by a light receiving element (not shown) or the like, and a temporary aperture diameter is selected.

The diaphragm plate 30 in this embodiment is provided with diaphragm holes 30B to 30D having three kinds of diaphragm diameters, and the diaphragm diameter selected in the pre-exposure is any one of the diaphragm holes 30B to 30D. is there.

Therefore, the operation of the diaphragm plate 30 will be described with reference to FIG.

In the present state shown in FIG. 2, the hook portion 31f of the locking claw 31 is locked to the locking portion 30a on the diaphragm plate 30, and in this state the image pickup device 1 is shielded from light. Assuming that the aperture hole 30B is selected in the previous photometry, the magnet 33 is given one electrical pulse. Therefore, the magnet 33 sucks the armature part 32a of the armature 32 against the elastic force of the coil spring 32b, so that the armature 32 rotates counterclockwise, and the hook part 32f of the armature part 32a is fixed to the base end part of the locking claw 31. 31k is pressed to rotate the locking claw 31 clockwise against the tension of the coil spring 31S.
Since the hook portion 31f is disengaged from the locking portion 30a as indicated by the z-dot chain line, the diaphragm plate 30 is moved in the direction of arrow M by the coil spring 30S, and the hook portion 31f contacts the slant portion 30e in the groove 30M. .
While Armature Your 32 is being attracted to Magnet 33,
Since the locking claw 31 cannot return to the original state, when the hook 31f contacts the slant 30e earlier than the armature 32 returns, the diaphragm plate 30 is stopped in the contact state. After that, the suction force of the magnet 33 is lost and the armature 32
Is returned or the contact is slower than the return of the armature 32, the hook portion 31f returns to its original state while sliding in contact with the slant portion 30e, and the next locking portion 30b and a new locking portion 30b. The diaphragm plate 30 is stopped by locking. Therefore, a diaphragm hole 30 is provided on the optical axis 2.
B is located. In order to position the diaphragm hole 30C on the optical axis 2, it is sufficient to apply an electric pulse to the magnet 33 once more, and when it is desired to position the diaphragm hole 30D, it is possible to further overlap and apply an electric pulse once. .

When the diaphragm is selected by the diaphragm device 3 and the diaphragm plate 30 is moved, pre-exposure is performed by the image sensor 1 which is partially shielded by the front blade 41 of the shutter device 4, and is used to obtain the main photometric output. It At this time, approximately 40% of the bottom of the image sensor 1
As shown in FIG. 1, it is often the case that an extremely bright portion with respect to the subject such as the sky is present in this portion (note that the subject image is turned upside down by the image pickup optical system,
(It forms an image on the image pickup device 1), it is not necessary for photometry, and in the case of an image pickup device having no storage unit as in the present embodiment, this light shielding unit can be used as a storage unit,
Moreover, by accumulating the subject portion near the center at the end portion of the light receiving surface of the image pickup device 1, the transfer time of the charges of the subject portion near the center can be shortened.

In this way, photometry is performed by the image sensor 1, the aperture value and the shutter speed value are finally determined, and the main exposure is performed.

First, the diaphragm plate 30 moves until the diaphragm hole selected by the diaphragm device 3 is located on the optical axis 2. At the same time, the front blade 41 of the shutter device 4 rotates in the clockwise direction and stops at the position where the image sensor 1 is entirely shielded. When the diaphragm is determined, the leading blade 41 further rotates in the same direction, the image pickup element 1 starts exposure, and the trailing blade 51 follows the leading blade 41 in accordance with the shutter speed determined previously. When the image pickup device 1 is rotated, and the rotation is completed, the entire surface of the image sensor 1 is shielded.

 The above operation will be described in more detail with reference to FIG.

In the same figure A, the front blade 41 makes up 30% of the lower part of the image sensor 1.
The image sensor 1 is exposed to the light incident through the hole of the plate 30 while pre-exposure, that is, the diaphragm plate 30 is moved to a predetermined position determined by pre-photometry or the like while being shielded to some extent. It This image sensor is read out after a predetermined accumulation time has elapsed due to pre-photometry or the like, and by using this output, a photometric output is formed and the final diaphragm is determined. When the predetermined shutter time elapses after the diaphragm plate 30 moves to the predetermined position, the magnet 43 is energized and the armature part 42a of the armature 42 is attracted to the yoke 43y, and the armature 42 is rotated clockwise around the shaft 42j. The driving member 42k pushes the base end portion 44k of the locking member 44 up against the tension of the coil spring 44S, so that the locking member 44 moves toward the shaft 4a.
Rotate counterclockwise around 4j Knives 44f and protrusions 41a
Unlock and. Therefore, the leading blade 41 is the coil spring 41.
It is rotated clockwise by the tension of S, and as shown in FIG. 7B, it hits the inner peripheral side surface 41b ₁ of the hook portion 44f of the locking member 44 and the other projection 41b on the holding portion 41H of the leading blade 41. Stop in contact. In this state, the image pickup device 1 is shielded from light and reset (all signal charges are read out from the device), and preparation for main exposure is completed. As the reset is completed, the magnet 43
When the power to the armature 42 and the locking member 44 is restored to the original initial state when the power is turned off, the hook portion 44f moves toward the inner side surface 41b ₁
And the coil spring 41 is disengaged as shown in FIG.
Side surface on the outer peripheral side of the protrusion 41b further rotated clockwise by S
The front blade 41 is brought into contact with 41b ₂ and stopped at a position where the image sensor 1 is not shielded.

In this way, the leading blade 41 can take two stages of positions by the ON / OFF operation of the magnet 43.

That is, in the initial state, the shutter device 4 shields about 40% of the lower portion of the image sensor 1, performs pre-exposure, and performs photometry,
Determine the aperture and shutter speed. And magnet
When 43 is turned on, the front blade 41 is rotated to a position where the image pickup device 1 is completely shielded from light, resetting the image pickup device, and then deenergizing the magnet 43 to start main exposure. Subsequently, the locking member 54 and the rear blade 51 are unlocked by energizing the magnet 53 shown in FIG. 1, and the rear blade 51 is rotated clockwise by a coil spring 51S to hit a stopper (not shown). It plays a role of shielding the image sensor 1 after the main exposure.

When the main exposure is completed in this manner, the diaphragm plate 30 resists the tension of the coil spring 30S by a charge mechanism (not shown) in the direction opposite to the arrow M, and the leading blade 41 and the trailing blade 51 move toward the coil springs 41S and 51S. Each of them is moved counterclockwise against the tension and returned to the initial position to complete the charge.

The positional relationship of the front blade 41 and the rear blade 51 with respect to the direction of the optical axis 2 is such that the blade that shields a part of the image sensor 1 during the pre-exposure is closer to the image forming unit, that is, the image sensor 1. The boundary between the light-shielded portion and the non-light-shielded portion becomes clear, so that the image sensor can be effectively shielded from light. Further, by using the blade that shields a part of the image pickup device 1 during the pre-exposure as the front blade 41, it is possible to perform a series of exposure sequences by moving in the same direction.

Next, a second simpler configuration having the same function as described above
An embodiment will be described with reference to FIG.

In contrast to the first embodiment in which the first embodiment uses two blades, ie, the leading blade 41 and the trailing blade 51, this embodiment is composed of one blade.

As shown in FIG. A, the blade 61 has a shape in which three leading blades 41 are continuously provided, and one central blade is formed as a main exposure hole 61A. The structure is almost the same as that of the shutter device 4 of the first embodiment except that 61d is provided. Since the diaphragm device is the same as that of the above-mentioned embodiment, its explanation is omitted.

In FIG. A, in the state where the locking member 44 and the protrusion 61a are locked, the imaging element 1 is covered by the blades 61 at the lower portion by about 40%.

When the pre-exposure is completed and the magnet (not shown) is energized, the locking member 44 is released from the protrusion 61a, and the blade 61 is rotated clockwise by the tension of the coil spring (not shown). Then, the rotation is stopped by being locked by the protrusion 61b, and the image sensor 1 is completely shielded as shown in FIG. Then, when the magnet is de-energized, the locking member 44 is released from the projection 61b and locked with the projection 61C as shown in FIG. In this state, the image pickup device 1 is exposed through the exposure hole 61A and, after a time corresponding to the shutter speed, when the magnet is again energized, the locking member 44 is released from the protrusion 61C as shown in FIG. Then the blade 61 further rotates,
The locking member 44 is locked to the protrusion 61d, the rotation is stopped, and the exposure is completed.

The charge mechanism of the exposure control member performed after the exposure is completed in the apparatus of the first embodiment described above will be described with reference to FIG. 5A, 5B and 5C are views showing the main part of the charge mechanism of the shutter front blade 41 whose plane is shown in FIG. 3, and FIG. 5A is the exposure state shown in FIG.
FIG. B corresponds to the light-shielded state shown in FIG. 3B, and FIG. 5C corresponds to the charge completed state shown in FIG. 3A.

In FIGS. 5A, B and C, M is a charge motor, G _{1 to} G ₃
Is a gear for transmitting the driving force of the motor M, and C is a cam connected to the gear G ₃ . On the front curtain 41, there is a roller K that can be lifted by a cam C made integrally with the gear G ₃ . The gear G ₃ is connected to the motor M via the gear G ₂ and the gear G ₁ . SW is a photo interrupter and controls the rotation of the motor by detecting the presence or absence of a blade. When the motor M starts rotating clockwise in the drawing in the state shown in FIG. 5A, the gear G ₃ and the cam C rotate clockwise, and the roller C is pushed upward by the cam C, The front curtain 41 starts rotating counterclockwise. The state shown in FIG. 5C is reached through FIG. 5B. In this state, the roller K has been charged by the cam C to almost the initial state. Then, the photo interrupter SW detects the blade and stops energizing the motor M. The gear G ₁ ~G ₃ further rotates by inertia than the state of FIG. 5 C, roller K enters the place where fell most of cam C, that the cam is finished Chiyaji by one revolution. At this time, the leading blade of the shutter is locked by the locking member 44. Also, the rotation angle required for exposure of the rear curtain is smaller than that of the front curtain 41. Therefore, the front curtain can hook the rear curtain from the middle of the charge of the front curtain 41, and can be charged with the same mechanism. Also, as shown in FIGS. 5A, 5B, and 5C, the charge of the expansion device 3 also causes the cam to rotate once to convert the rotary motion into a linear motion, and to move it in the M direction in FIGS. 1 and 2. Contrary to the above, the diaphragm plate 30 can be moved for charging.

Further, as an embodiment other than the first and second embodiments, a dedicated blade may be provided to block a part of the image forming portion during the pre-exposure, and a total of three blades including a front blade and a rear blade may be used. The displacement limiting device 40 in the shutter device 4 of the first embodiment is used to maintain the position of the leading blade 41 by continuously energizing the magnet 43 as shown in FIG. 3B. As described above, a method may be adopted in which an electric pulse is applied to the magnet once, and the magnet is rotated by a certain predetermined amount corresponding to the number of times. Accordingly, the power consumption of the image pickup device can be reduced.

Instead of using the output of the image sensor to perform the main light measurement, the light receiving element may receive the reflection from the shutter surface or the image sensor surface (the film surface in the case of a silver salt camera) for light measurement.

As described above, according to the present embodiment, after the pre-photometry, a part of the effective luminous flux is blocked by a part of the shutter, that is, the high-luminance part such as the sky is blocked, and the main photometry is performed by the signal from the imaging unit. Since the main exposure is performed after performing the pre-exposure, there is an effect that the exposure control can be performed with higher accuracy than that in the main exposure that is performed only by the pre-metering.

Further, the exposure control can be speeded up as compared with the case where the main exposure is performed only by the output of the image sensor.

Next, an example of an electric circuit of the image pickup device configured as described above will be described with reference to FIG.

 FIG. 6 is a block diagram of an example of such an electric circuit.

In FIG. 6, 1 is a CCD as an image pickup device, 1'is an image pickup optical system, 3 is a diaphragm device, and 4 is a shutter device, as shown in FIG.

Reference numeral 5 is a signal processing circuit for adding various corrections to the luminance component and color component in the output signal of the CCD 1, and 6 is an integration for integrating the luminance signal appropriately formed in the signal processing circuit and sample-holding for each field. Circuit. Reference numeral 7 is an A / D converter, and the value A / D converted by the A / D converter 7 is taken into the control circuit 111. Reference numeral 13 is a sample and hold circuit that samples and holds the output of the SPC 19, which is a photometric element. Reference numeral 14 is an A / D converter for A / D converting the value held by the sample hold circuit 13. Reference numeral 15 is a half mirror provided in the image pickup optical system. Reference numeral 17 is a servo circuit that controls the rotation state of a motor 29 that rotates the magnetic sheet 27.

Reference numeral 19 denotes the above-mentioned SPC, which is provided separately from the image sensor 1. A recording gate 20 controls whether or not the image signal from the signal processing circuit 5 is sent to the recording circuit 21.

Reference numeral 21 denotes the recording circuit, which is a circuit for modulating the image signal output from the signal processing circuit 5 into a form recordable on the magnetic sheet 27 via the head 25. 22 is a release circuit. 23 is a half mirror for guiding a part of the reflected light of the half mirror 15 to the finder optical system 24, 25 is the head,
27 is the magnetic sheet. Reference numeral 26 is a clock generation circuit for driving the image pickup device 1, and the timing of the clock generated by the control circuit 111 is controlled.

28 is a synchronous clock generator for generating a reference clock for synchronizing the entire system, and 100 is a diaphragm shutter drive circuit for driving the magnets 33, 43, 53 described above in FIG. 1 based on a command from the control circuit 111. Is.

The control circuit 111 functions as a control means for the diaphragm device 3, the shutter device 4, and other circuit blocks, and outputs the release circuit 22 and a synchronous clock generator 28 for forming a release signal in conjunction with a release button (not shown). Of the control outputs X _{1 to} X ₃ as shown in the flow chart of FIG. 9.

Next, the internal configuration of the clock generation circuit 26 will be described.

FIG. 7 is a block diagram showing the internal structure of the clock generation circuit 35. In FIG. 7, reference numeral 100 is a counter for counting the number of output pulses of the OR gate 107, and the value of the data buses D0 to D3 from the control circuit 111 is loaded by the LOAD pulse 120 which is the output of the OR gate 106, and this value is used as an initial value for RS. UP-COUNTER for counting when the enable signal 121 output from the flip-flop (RS-FF) 103 is at high level. 122 is a carry signal generated when the counter reaches the full count. This counter has a sufficient capacity to count the number of pixels in the vertical direction of the image sensor (CCD) 1. For example, in this embodiment, the number of vertical pixels of CCD 1 is 250, and the counter generates a carry signal when the count value reaches 250. 101 is a circuit for vertically transferring the charge accumulated in CCD1 and generating a timing signal for clearing CCD1, which is the output of RS-FF104 shown in 123.
A transfer pulse is generated when the le signal is high level. still
D0 to D3 are the control circuit 111 and the clock generation circuit 2 as described above.
The data bus is provided between the data bus 6 and 6 and the number of data buses is four in the embodiment, but the number is not limited to this. WR0 and WR2 are control lines provided between the control circuit 111 and the clock generation circuit 26, and RD0 is a determination line for determining the state of the clock generation circuit 26. Reference numeral 102 is a circuit for generating a timing signal for reading the charges accumulated in the CCD, and generates a transfer pulse when the enable signal output from the RS-FF 105 shown at 124 is at a high level.

An example of the structure of the CCD 1 used in this embodiment will be described with reference to FIG.

In FIG. 8, reference numeral 200 denotes an image pickup unit in which stripe filters of R, G, B3 primary colors are provided in the vertical scanning direction, and in this embodiment, 250 pixels are arranged in the vertical direction. The image pickup unit 2
Reference numerals A, B, and C shown in 00 are added for convenience of description later, and although there is no difference in structure, the portion indicated by C is the shutter front blade 41 at the position shown in FIG. 3A. This is a portion that is shielded from light by 100 lines in this embodiment. Also, B is 50
Row, C is for 100 rows. A photoelectric variation is made in the image pickup unit, and charges corresponding to the amount of incident light are accumulated in each pixel. Reference numerals 201 to 203 are horizontal transfer registers for reading out a video signal transferred from the image pickup section 200. In the present embodiment, the CCD 1 receives a light beam when the diaphragm device 3 and the shutter device 4 are open, and in this photometry, after the shutter device 4 is transferred to the light shielding part C before the shutter is closed, the main exposure is performed again. Then, after the shutter device 4 is closed, the charges are sequentially transferred to the horizontal transfer registers 201 to 203 for each horizontal line. The charges accumulated in the pixels provided with the R stripe filter in 201 and the charges in 202 are indicated by G. The charge accumulated in the pixel provided with the stripe filter and the charge accumulated in the pixel provided with the B stripe filter in 203 are discriminated by the pulses shown in φ _S1 and φ _S2 in FIG. After that, horizontal transfer is performed by horizontal transfer pulses φ _H1 , φ _H2 , and φ _H3 .
Reference numeral 205 is an output amplifier unit that amplifies the signals read from the horizontally transferred registers 201 to 203. Reference numeral 220 denotes a drain, so that when the transfer pulse generated by the generation circuit 101 for vertically transferring the portions A and C in the image pickup unit 200 is generated, the electric charges remaining in the horizontal shift registers 201 to 203 without being horizontally transferred flow into the drain. It is located in.

The image pickup unit 200 is supplied with the transfer pulse φ _V shown in FIG. 3, and the horizontal registers 201 to 203 are supplied with the transfer pulses φ _{H1 to} φ _H3 and φ _S1 and φ _S2 shown in FIG. There is.

Further, the circuit for generating these pulses can be realized by combining the output of the counter circuit with the logic gate, and the detailed description will be omitted here.

103 is set by the high level output of the OR gate 106, and reset by the rise of the carrier signal 122 of the carunter 100 RS-FF 104, 105 are set by the high level outputs of WR0 and WR2 from the control circuit 111, respectively. RS-FF reset by the rise of carrier signal 122
Is. Reference numerals 107 to 112 denote OR gates that take the logical sum of the pulses output from the clear transfer pulse generation circuit 101 and the read pulse generation circuit 102 at different timings, and are respectively connected to the CCD 1 as described above.

Next, the operation of the embodiment constructed as described above will be explained.
This will be described with reference to the drawings.

FIG. 9 is a flow chart for explaining the first operation example of the control circuit 111 shown in FIG.

First, it is determined whether or not a signal indicating that the release switch is turned on is obtained from the release circuit 22 (S1), and if so, the sample hold circuit 13
Is driven to capture the output of SPC19 which is a photometric element as a photometric value (S2). Next, depending on the metering value that was captured, the TV
A value and an AV value are calculated (S-1). In the diaphragm device 3 of this embodiment, there are three diaphragm holes, 30B, 30C, and 30D, so any one of the three AV values is selected, and the selected AV value and photometric value are selected. Since the TV value is calculated, the TV value is a continuous value. Next, the magnet 33 is energized according to the calculated AV value, and the diaphragm plate 3 shown in FIG.
In the direction (S-2). Due to this, the lower part C of CCD1
Is shielded by the shutter front blade 41 as shown in FIG. 3A, but the upper portions A and B are exposed. At the same time as the driving of the diaphragm is started, the control circuit 111 sets the control line WR0 to the high level shown in FIG. 6 and sets "0" to the data lines D0 to D3 (S4-1). Therefore, "0" is loaded into the transfer pulse counter 100, and RS-FF104 is set. Therefore, the clear transfer pulse generation circuit 101 outputs a pulse such as the vertical transfer pulse φ _V described above, and the imaging unit 20 of the CCD 1
The unnecessary charges accumulated in 0 until then are cleared. The transfer pulse counter 100 counts the above-mentioned pulse φ _V , and when the pulse φ _V reaches 250 pulses, that is, when all the signals accumulated in the image pickup unit 200 are transferred, a carrier signal 122 is output, but control is performed. Circuit 111 is a carrier signal
By determining 122, it is determined whether the transfer is completed (S4-2).

Next, it is determined whether or not TV, which is the calculation result of S3-1, is equal to or lower than a predetermined _TV0 (for example, _TV0 = 9) (S4-3).

T _V ≤ T _V0 (= 9) means that the shutter speed is 1
Since it is longer than / 500, proceed to step S5 in this case.

Next, it is determined whether or not the flag described later is set (S5). If the flag is not set, the above-mentioned S3 is set.
Wait only for the shutter time calculated in -1 (S7).

The diaphragm drive performed in S3-2 is the magnet 33
Even if the power is turned on, there is a delay of a predetermined time until the diaphragm is actually opened due to the response delay of the mechanical power transmission unit, such as the armature unit 32 and the locking claw 31, but the CCD1 performed in S4-1 and S4-2. Clearing the charge accumulated in each pixel is completed within an extremely short time, so the aperture actually opens.
When the CCD1 is exposed, the charge of each pixel of the CCD1 has already been cleared.

After waiting for the TV value calculated in S7, the magnet 43 shown in FIGS. 1 to 3 is energized (S8). As a result, the shutter device 4 shifts from the state shown in FIG. 3A to the state shown in FIG. 3B.

Following the energization of the magnet 43, the control circuit 111 sets the terminal WR0 to the high level and sets "150" in D0 to D3 (S
-9).

Therefore, a high level signal is input to the input terminal S of the RS-FF 104, and the data of 150 set by D0 to D3 is loaded into the transfer pulse counting counter 100.

RS-FF 104 is cleared transfer pulse generating circuit 101 starts to operate in response to that is excisional at the next clock signal, and generates a pulse such as the aforementioned phi _V. During this period, vertical transfer is performed at a higher speed than usual. Here, when φ _V reaches 100 pulses, the count value of the transfer pulse counter 100 becomes 2
The counter signal is output from the counter 100 as 50.

The RS-FFs 104 and 105 are reset in response to the carrier signal, and the generation of the transfer pulse is temporarily stopped. Then the control circuit
111 judges that the transfer is completed by the carrier signal, and then S11
The flow proceeds from 15 to 15. At this point, B shown in FIG.
The electric charge of the part of is transferred to the part indicated by C.

Even when the shutter is driven in S8, the shutter actually travels from the position shown in FIG. 3A to the position shown in FIG. 3B due to the response delay caused by the mechanical power transmission unit as in the above-described diaphragm drive. Although there is a delay of a predetermined time before, the charges of the image pickup unit are transferred at an extremely high speed by executing S9 and S11, so that the charges of the portion shown in FIG. The signal is transferred from the beginning shown in C to the portion shielded from light by the shutter, and the signal is prevented from being deteriorated by the influence of external light after the transfer is completed.

Further, the time when the charge integrated by the integrating circuit 6 is generated, that is, after the image pickup unit 200 of the CCD1 is cleared in S4-1 and S4-2, the area indicated by B of the image pickup unit 200 of the CCD1 is changed to C in S9 and S11. The time until transfer to the area shielded by the shutter front blades shown does not depend on the response delay of the mechanical power transmission system of the shutter device, and
Depends only on the timing of the control signal supplied from the clock generator circuit 26 to the clock generator circuit 26. Therefore, in this embodiment, the pre-exposure time can be controlled extremely accurately.

Next, the control circuit 111 sets the control line WR2 to high level.
Set "200" to D0 to D3 (S15).

Therefore, a high level signal is input to the input terminal S of the RS-FF 105, and 200 data set by D0 to D3 are loaded into the transfer pulse counting counter 100.

The read pulse generation circuit 102 starts operation in response to the RS-FF105 being set by the next clock signal,
The pulse of φ _V described above is generated. Since the pulse generated by the read pulse generation circuit 102 is a normal read pulse, the signals of 50 rows of the signals in the light shield section C of the image pickup section 200 are read from the horizontal shift registers 201 to 203 and read. As described above, the output signal is the integration circuit 6 shown in FIG.
Is integrated by. The output of the integrating circuit 6 is fetched in S24 described later.

In this case, since most of the video signals for 100 lines in S9 and S11 are discarded to the drain 220, the video signals for 50 lines in the center of the screen are used for such integration.

Therefore, as described above, the signal of a high-luminance portion such as the sky that forms an image on the lower part of CCD1 is not used for such integration.

That phi _V 50 pulses output by the count value 250 becomes a transfer pulse number counter 100, the carry signal from the counter 100 is output. When it is detected that the reading is completed by detecting the carrier signal, the flow proceeds from step S17 to step S19.

Steps S19 and S21 are the same as steps S9 and S11 described above, and since they are steps for clearing 100 lines in the portion of FIG. 8A, description thereof will be omitted.

When the transfer of the image pickup unit 200 is completed as described above, the flag is set in S23, the flow returns to S5, and then the flow branches from S5 to S24.

Next, the integrated value of the integrating circuit 6 shown in FIG. 6 is fetched from the A / D converter 7 (S24), and the TV value is recalculated from the integrated value so that the integrated value becomes a predetermined value. Get the actual shutter speed TV value for optimum exposure (S25). Then, the magnet 43 is de-energized (S26) and the shutter is set to the third position.
The main exposure is started by moving from the position shown in FIG. B to the position shown in FIG. 3C.

Next, after waiting for only the actual shutter time TV (S27), the magnet 53 is energized, the rear blades 51 are made to run, and the front surface of the CCD 1 is shielded.

In S30, the terminal WR2 is set to a high level and D0 to D3 are set to "0". Then, in the same manner as described in S15, the read pulse generation circuit 102 starts to operate, the normal reading is started from the image pickup unit 200, the recording gate 20 is opened in S32, and the recording circuit 27 opens one screen image. The signal is recorded.

When the end of the transfer is detected, that is, when the recording circuit 27 completes recording the video signal for one screen, the flow proceeds from S34 to S36, the recording gate 20 is closed and the charge motor is energized (S38), and the fifth The shutter and aperture are charged until the state of the switch SW shown in the figure is switched, and when this charge is completed, the flow is all completed and returns to S1.

In the case of No in step S4-3, that is, in the case of T _V > T _V0 , the process proceeds to S4-4 and T _V ′ is set to T _V1 in FIG.

This is for the following reason. In other words, in S4-3, if T _V > T _V0 , the shutter speed is shorter than 1/500. This is performed by controlling the accumulation time from S5 to S23, and is calculated as T _V ′ in S25, the time required for transferring the portion B of FIG. 8 to the portion C of FIG. 8 by the accumulation time S9 and S11. Becomes relatively long and the S / N becomes large. In addition, even if the shutter is closed after energization of Mg43 in S8, it is actually due to the diffraction of light.
There is a drawback that noise enters during reading in S15 and S17.

This drawback becomes more remarkable as the accumulation time becomes shorter. Therefore, in the embodiment of the present invention, when the shutter speed is too fast, A _V =
Using A _V1 and T _V = T _V1 as they are, start the main exposure in S26.

This not only reduces unnecessary sequences and prevents the escape of the shutter timing, but also allows more accurate exposure control without erroneous exposure control based on noise.

As described above, in the present embodiment, pre-photometry is performed by the SPC 19, and after the combination of the diaphragm and the shutter is once set, the diaphragm is set to the set value during the preset shutter time in the previously controlled state. When transferring the accumulated image sensor signal and shielding the image sensor and performing exposure control according to the signal, the image sensor signal of the part not used for exposure control is read out at high speed and discarded. The exposure can be controlled extremely accurately so that the output is constant, and the time lag from the release signal output from the release circuit 22 to the actual image recording can be made extremely small. If this is attempted only by the output of the image sensor, the dynamic range will be narrow, so unless the feedback control is repeated many times, it will not be stable.

In the configuration of the clock generation circuit 35 of this embodiment shown in FIG. 7, the pulse output from the clear pulse generation circuit 101, the pulse output from the read pulse generation circuit 102,
Since the same counting counter 100 is used to count the number of any pulse, the structure can be extremely simple.

Also, the counting counter 100 is a presettable canter,
Since the clock generation circuit 35 is configured so as to be preset from the outside of the clock generation circuit, it is possible to read the signal of any portion other than the central portion of the screen of the image pickup device in an extremely short time as in the present embodiment, and it should be read. The size of the part can be freely set from the outside. As a result, such a clock generation circuit can be used for exposure control and also for applications such as evaluation photometry. That is, the present invention can be used in applications such as evaluation photometry.

In the present embodiment, the up counter is used as the counter for counting the transfer pulse, but this may be of course a down counter. In this case, the value of the pulse number itself to be transferred may be preworded.

Next, FIG. 10 shows another embodiment of the operation example shown in FIG. 9, and FIG. 11 is a view showing a structural example of an exposure mechanism such as a diaphragm suitable for this embodiment.

The difference between the present embodiment and the example shown in FIG. 9 is that in the present embodiment, the first exposure and the second exposure are performed to re-expose the exposure. Only the differences from FIG. 9 will be described below.

After A _V = A _V1 and T _V = T _V1 are obtained in S3-1, T _V is obtained in S3-1
= T _V0 (T _V0 is, for example, 9) is determined, and if Yes, the first and second exposures similar to those in FIG. 9 are sequentially performed to re-exposure.

On the other hand, if it is determined in S3-1a that T _V > T _V0 , S
In 3-1b, set A _V = A _V0 . Here, A _V0 is the aperture value of the specially provided hole 30B ′ having a very small aperture value (passage amount) as shown in FIG.

In this embodiment, 30B 'is provided with an ND filter 30B ", which substantially reduces the aperture value of the relatively large aperture 30B'. This reduces the aperture value only by reducing the aperture size. This is because if it is made smaller, diffraction will occur due to the thickness of the diaphragm plate.

Now, in this way, in S3-1b, A _V = A _V0 is set and the aperture value is made smaller than the original diaphragm, and then T _V is calculated from T _V = E _V −A _V0 . Here E _V are those measured in S2 in exposure value.

This T _V is smaller than T _V1 . That is, the shutter time becomes longer.

After that, the state of A _V = A _V0 is set in S3-2, the first exposure is performed, and only T _V = E _V −A _{V0 is} accumulated in S7, and then S9, S11
Then, the signal of FIG. 8B is transferred to C and read out at S15 and S17, and then at S24 the photometric result E _V ′ is obtained from the integrated value.

Next, in S25, T _V ′ = E _V ′ −A _V1 is calculated, and then S25-1
Set the aperture to A _V1 with. When T _V ≤T _V0 in S3-1a, the aperture remains A _V1 , but in S25-1 the aperture is surely set to A _V1 .

The subsequent main exposure operation is the same as that shown in FIG. 9, and therefore description thereof will be omitted. According to the above-described embodiment, correct exposure can be always re-issued by the first and second exposures, and an error due to a short accumulation time can be prevented. it can.

〔The invention's effect〕

As described above, according to the present invention, since the light-shielding unit that stops in a state in which only a part of the light-receiving surface of the image sensor is shielded from light is used, the output of the image sensor obtained in such a state is used. Therefore, for example, the exposure value can be controlled without being affected by a bright portion such as the sky.

Further, according to the first invention of the present application, extremely accurate exposure control can be performed in the first mode by the first and second exposures, and
In the case where a high speed shutter time is required, which makes it difficult to perform the first exposure, the exposure control structure can be simplified by omitting the first exposure. That is, the exposure control structure becomes extremely complicated when trying to realize the first mode under any subject condition, but the structure can be made extremely simple by adopting the second mode depending on the condition.

Further, according to the second invention of the present application, extremely accurate exposure control can be performed by the first and second exposures, and when the subject is particularly bright, the aperture of the first exposure is made smaller than that of the second exposure. Therefore, the shutter time (accumulation time) of the first exposure can be made relatively long, and the structure for performing the first exposure can be simplified.

[Brief description of drawings]

FIG. 1 is a perspective view of a diaphragm device and a shutter device according to a first embodiment of the present invention, FIG. 2 is a front view of the diaphragm device, FIG. 3 is a front view showing the operation of the shutter device, and FIG. FIG. 4B is a diagram showing a state where the entire surface of the image sensor 1 is shielded by the front blade 41, and FIG. C is a diagram showing a state where the front blade 41 is running and the image sensor is exposed. FIG. 4 is a view for explaining another embodiment of the shutter device 4 used in FIG. 1, and FIGS. 4A to 4C correspond to FIGS. 3A to 3C, respectively. FIG. D is a diagram showing a state where the entire surface of the image pickup device 1 is shielded from light, FIGS. 5A, 5B and C are diagrams showing a charge mechanism of the shutter device shown in FIG. 1, and FIG. 6 is a diagram showing the image pickup device. FIG. 7 is a block diagram of the electric circuit, FIG. 7 is a block diagram showing the internal structure of the clock generation circuit shown in FIG. 6, and FIG. 8 is a plan view of the CCD which is the image sensor 1. 9 view, FIG. 10 is a flow chart example for explaining the operation of the control circuit 111 shown in respectively Figure 6. FIG. 11 is a perspective view of a diaphragm device and a shutter device suitable for the flow chart of FIG. 1 ... Image sensor 2 ... Optical axis 3 ... Aperture device 4 ... Shutter device 26 ... Clock generation circuit 111 ... Control circuit

Claims (1)

(57) [Claims] 1. An image pickup unit, a light receiving unit provided separately from the image pickup unit, first photometric information is formed based on an output of the light receiving unit, and the image pickup unit is formed based on the first photometric information. First exposure is performed, second photometric information is formed based on a signal formed in the image pickup means by the first exposure, and then the second exposure is performed.
Is controlled so as to perform the second exposure on the image pickup means in accordance with the photometric information of 1., and when the output of the light receiving means is larger than a predetermined level, the aperture for the first exposure is set to the aperture for the second exposure. An image pickup apparatus comprising: an exposure control unit that further reduces the size; and a recording unit that records the signal formed in the image pickup unit by the second exposure as an image signal.