JP2004056331A - Image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image pickup device in which the release time lag can be shortened, accurate exposure control can be executed, and photographing chances are not missed. <P>SOLUTION: The image pickup device has a light intensity adjusting means using physical property elements capable of changing the light transmittance and an exposure control means which sets exposure time and the light transmittance of the light intensity adjusting means. The image pickup device is constituted to have a storage means to store information regarding the physical property elements beforehand and a control means to control the light transmittance to be adjusted by the light intensity adjusting means on the basis of the information regarding the physical property elements stored in the storage means. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image pickup apparatus, and more particularly to an improvement in a release time lag in an image pickup apparatus such as a camera having a light amount adjusting means using a physical element such as an electrochromic (EC) element whose light transmittance changes.
[0002]
[Prior art]
2. Description of the Related Art In recent years, various imaging devices such as digital cameras and digital video cameras equipped with an imaging element having a high pixel count and a fine pixel pitch have been developed. However, when the pixel pitch of the image sensor becomes narrower, the diffraction phenomenon at the edge of the opening becomes conspicuous in the conventional mechanical diaphragm device, and the image deteriorates, and the pinhole effect causes dust and scratches on the lens. There are problems such as the appearance of dust and scratches on the image sensor surface and dust and other dust in the optical path. It was difficult to reflect the intention of drawing.
As a remedy, an image pickup apparatus equipped with a so-called physical stop such as an electrochromic element that changes the light transmittance has been invented.
[0003]
First, the operation of an electrochromic element applicable to the physical property stop will be described.
The electrochromic element is disclosed in, for example, Japanese Patent Application Laid-Open No. 56-4679, and is an all-solid-state optical filter element having a variable spectral light transmittance depending on voltage, having a structure as shown in FIG. is there. In FIG. 9, Ta is inserted between transmission coating electrodes 901 and 902 such as Ito. ₂ O ₅ , SiO ₂ Through the insulating coating layer 903 such as, for example, the oxidized coloring coating layer 904 such as lrOx and the reduced coloring coating layer 905 are colored, and the transmission characteristics are changed. These are formed on a glass base 906.
It has been proposed to use an electrochromic element having such characteristics as a substitute for a diaphragm device or in combination with a diaphragm device. However, because the time until the light transmittance of the electrochromic device is stabilized is slow. However, it has not been widely used until now.
[0004]
FIG. 10 shows the operation response characteristics of a conventional electrochromic device, which will be described. FIG. 10 shows the characteristics when the light transmittance of the electrochromic element is reduced (the density is increased). The vertical axis indicates the concentration (%) of the light transmittance of the electrochromic element, and the horizontal axis indicates the light transmission. The time until the rate stabilizes (sec) is shown. In addition, the driving potential when 0.5 V, 1 V, 2 V, and 3 V are applied is shown as a parameter. For example, in the case where the light transmittance is changed from 75% to 25%, when 1 V which is a potential to reach the target light transmittance is applied, a response time until the target light transmittance is stabilized takes about 1 sec.
Therefore, in order to improve the response speed, the present applicant has proposed, in Japanese Patent Application Laid-Open No. Hei 9-211497, an invention on light amount control means for applying a target voltage after applying a voltage higher than the target voltage for a predetermined time. ing.
[0005]
[Problems to be solved by the invention]
As described above, the influence of diffraction can be eliminated by using a physical element such as an electrochromic element, but the release time lag until actual shooting is required due to the reaction time required until the light transmittance is stabilized. The release time lag varies because the time until the light transmittance of the element stabilizes differs depending on the length of the conventional mechanical diaphragm or the set light transmittance (aperture value), and the shooting timing is out of sync. There was a case.
Also, in the invention described in Japanese Patent Application Laid-Open No. Hei 9-212497, a voltage higher than the target voltage is applied to accelerate the reaction, but the exposure waits until the light transmittance is stabilized. There was room for improvement in the release time lag.
[0006]
Accordingly, it is an object of the present invention to provide an imaging apparatus that can reduce a release time lag, perform accurate exposure control, and do not miss a shooting opportunity.
[0007]
[Means for Solving the Problems]
The present invention provides an imaging device configured as in the following (1) to (9).
(1) In an imaging apparatus having a light amount adjusting unit using a physical element capable of changing a light transmittance, and an exposure controlling unit for setting an exposure time and a light transmittance of the light amount adjusting unit,
Storage means for storing information on the physical element in advance, and control means for controlling light transmittance by the light amount adjusting means based on the information on the physical element stored in the storage means. Imaging device.
(2) The control means for controlling the light transmittance by the light quantity adjusting means, the light whose average light transmittance of the light quantity adjusting means is set by the exposure control means during the exposure time set by the exposure control means. The imaging apparatus according to the above (1), which is means for controlling so as to have a transmittance.
(3) The light quantity adjusting means is a light quantity adjusting means using a physical element whose light transmittance changes by applying a voltage,
The control means for controlling the light transmittance by the light quantity adjusting means is such that, during the exposure time set by the exposure control means, the average light transmittance of the light quantity adjusting means is equal to the light transmittance set by the exposure control means. The imaging device according to (1), wherein the imaging device is a unit that controls a voltage applied to the light amount adjustment unit according to an exposure time set by the exposure control unit.
(4) The storage means is a storage means for storing information on a change in light transmittance with respect to an application time for each applied voltage to the light amount adjustment means,
(3) wherein the control means for controlling the light transmittance by the light quantity adjusting means is means for controlling the light transmittance by the light quantity adjusting means based on the information stored in the storage means. An imaging device according to any one of the preceding claims.
(5) The light quantity adjusting means is a light quantity adjusting means using a physical element whose light transmittance changes by applying a voltage,
The imaging method according to (1), wherein the control unit that controls light transmittance by the light amount adjustment unit is a unit that changes an exposure start time according to an exposure time set by the exposure control unit. apparatus.
(6) There is provided a means for judging whether or not the exposure time set by the exposure control means is earlier than a predetermined time, and controlling to change the exposure start time according to the judgment result. The imaging device according to (1).
(7) means for changing the exposure start time according to the exposure time, wherein the light whose average light transmittance of the light amount adjusting means is set by the exposure control means during the exposure time set by the exposure control means; The imaging apparatus according to the above (5), which is means for controlling the exposure start time according to the exposure time so that the transmittance is obtained.
(8) The light quantity adjusting means is a light quantity adjusting means using a physical element whose light transmittance changes by applying a voltage,
The control means for controlling the light transmittance by the light quantity adjusting means is such that, during the exposure time set by the exposure control means, the average light transmittance of the light quantity adjusting means is equal to the light transmittance set by the exposure control means. The imaging apparatus according to the above (1), which is means for controlling a voltage application start time to the light quantity adjusting means according to an exposure time.
(9) The physical property element is an electrochromic element.
The imaging device according to any one of (1) to (7).
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
By configuring the imaging device by applying the above configuration, until the light transmittance of a physical element such as an electrochromic element is stabilized, without waiting for photographing, previously storing the light transmittance change of the physical element, Control such as applying a voltage to the physical element after the start of exposure or exposure starts during the change, and performing control in anticipation of the change in light transmittance, without being affected by diffraction In addition, it is possible to provide an imaging device that does not miss a shooting opportunity.
Further, by controlling the average light transmittance of the light amount adjusting means during the exposure time set by the exposure controlling means to be the light transmittance set by the exposure controlling means, the light transmittance of the light amount adjusting means is increased. Shooting can be started before the image is stabilized, which can contribute to shortening the release time lag.
Further, the light amount adjustment is performed according to the set exposure time so that the average light transmittance of the light amount adjustment unit during the exposure time set by the exposure control unit becomes the light transmittance set by the exposure control unit. By controlling the voltage applied to the unit, the photographing can be started before the light transmittance of the light amount adjusting unit is stabilized, and the release time lag can be reduced and the photographing can be performed at the same photographing timing.
In addition, a storage unit for storing light transmittance change data with respect to an application time for each applied voltage to the light amount adjustment unit is configured, and by performing control based on the data in the storage unit, accurate exposure control can be performed. it can.
In addition, by configuring the control unit that changes the exposure start time according to the exposure time set by the exposure control unit, it is possible to eliminate the possibility that the light amount of the exposed image becomes uneven. At this time, it is determined whether or not the exposure time set by the exposure control means is earlier than a predetermined time, and by performing control to change the exposure start time based on the determination result, the exposure time of the slit-shaped opening is controlled. The adverse effects of the case can be eliminated.
Also, a control for controlling the exposure start time according to the exposure time so that the average light transmittance of the light amount adjusting means during the exposure time set by the exposure control means becomes the light transmittance set by the exposure control means. By providing the means, it is possible to further reduce the release taum lug.
Also, a voltage applied to the light amount adjusting means according to the exposure time so that the average light transmittance of the light amount adjusting means during the exposure time set by the exposure controlling means becomes the light transmittance set by the exposure controlling means. By providing the control means for controlling the application start time, the release time lag can be kept constant regardless of the exposure time, and the shooting timing can be stabilized.
Further, by using an electrochromic element having a memory property as a physical element used for the light amount adjusting means, power saving can be achieved.
[0009]
Next, an embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is a block diagram schematically illustrating a camera system according to the present embodiment. In FIG. 1, reference numeral 100 denotes a camera body of a so-called digital camera that captures an image by an imaging unit, and 130 denotes an interchangeable lens that is attached to and detached from the camera body 100, and the camera system is configured by these.
In such a camera system, the subject 150 includes an optical system 138 in the interchangeable lens 130, a zoom lens group 139 serving as a variable power optical system, a focus lens group 140, and an electrochromic element (hereinafter, referred to as an EC element). The light passes through a stop 141 serving as a light amount adjusting means and enters a prism 111 with a built-in half mirror on the camera body side.
[0010]
Reference numeral 135 denotes a driving unit for the stop 141 of the light amount adjusting unit, which controls the light transmittance of the EC element by applying a voltage based on a signal from the lens CPU 137. Reference numeral 136 denotes an operation means, which is a so-called manual operation means, and can set zooming, focusing, aperture, automatic / manual switching of focus, and the like.
A lens CPU 137 exchanges information with the camera CPU 105 via the lens communication unit 131 and the camera communication unit 113, and controls the entire inside of the lens.
[0011]
Reference numeral 134 denotes a focus driving unit. In the present embodiment, the focus driving unit 134 includes a motor and its driving circuit. Further, driving of the focus lens group 140 in the optical axis direction is controlled in accordance with a signal from the lens CPU 137. Reference numeral 133 denotes a focal length detecting unit that detects the focal length by detecting the position of the zoom lens group 139.
[0012]
In the present embodiment, the position of the zoom lens is detected by a gray code pattern of 32 divisions (not shown). Reference numeral 132 denotes a ROM serving as a storage unit, which stores an ID of the interchangeable lens, focal length information, and physical property data of an EC element constituting the light amount adjustment unit, and is read from the lens CPU 137 at any time during exposure control. be able to.
Further, in the present embodiment, the physical property data of the EC element includes light transmittance information based on the voltage applied to the EC element (stable light transmittance data when a predetermined time has elapsed after the application of the voltage) and the light to be set. The voltage applied to the EC element selected by the transmittance and the set exposure time (shutter speed) is stored as data.
[0013]
Next, the light beam that has passed through the interchangeable lens 130 passes through the prism 111 having a built-in fixed half mirror, and forms an image on the imaging surface of the imaging unit 109. The imaging means 109 is configured by a photoelectric conversion element such as a CCD or a CMOS. In the prism 111, a part (1/3 in the present embodiment) of the light amount branches in the vertical direction and enters the pentaprism 108. A focus detecting unit 106 is arranged on the branched optical path in the pentaprism. The focus detection means 106 is a so-called phase difference detection method, which is equivalent to a method conventionally used in a silver halide camera or the like. In the present embodiment, an F8 light beam is used. It is divided and each is detected by a line sensor. The detection signal is output to the camera CPU 105. The light that has passed through the pentaprism 108 passes through the finder optical system 101 and can be visually recognized by a photographer as an optical finder image.
[0014]
Reference numeral 110 denotes a shutter unit, which controls an exposure time based on a signal from the camera CPU 105.
An output signal obtained by the light incident on the imaging unit 109 is amplified and output to the camera CPU 105 as a digital video signal. The camera system of the present invention forms a moving image or a still image using the video signal.
Reference numeral 107 denotes a photometric unit, which transmits photometric information to the camera CPU 105. The shutter speed (exposure time) and the light amount adjusting means 141 are controlled based on the photometric information. Reference numeral 102 denotes a two-stage switch. The first stage is a SW1 signal for starting photometry, focus detection, and focusing operation. The second stage outputs a SW2 signal for instructing the start of exposure recording by the imaging unit to the camera CPU 105. This is known release means.
[0015]
Note that the camera CPU 105 and the lens CPU 137 form the basis of the present system, and function as control means including control of the exposure control means and the light amount adjustment device. The camera CPU 105 communicates with the lens CPU 137, controls the display unit 103, controls input from the setting unit 104, controls the external storage unit 112 for recording and holding captured image data, checks the remaining capacity of the power supply 114, Responsible for all controls such as power sharing. In the present embodiment, a temporary memory for image signals and various buffer memories are also included in the camera CPU.
[0016]
FIG. 2 is a diagram schematically illustrating a change in light transmittance of an EC element of a light amount adjusting unit and a time chart related to exposure of an imaging apparatus according to the present embodiment.
In FIG. 2A, (0) three lines with different light transmittance changes starting from the start of the application of the EC voltage indicate the start of application of 0.5 V, 2 V, and 3 V in this figure due to the difference in the applied voltage to the EC element. Represents the change in the light transmittance from. As can be seen from this figure, it takes about one second (t0) after voltage application for the light transmittance change to stabilize. The release time lag was too long and could not be used. In the present embodiment, exposure is started before the light transmittance is stabilized, and the release time lag is reduced by correcting a change in the light transmittance. FIG. 2B is an enlarged view in the time direction near the start of (0) voltage application in FIG. 2 and will be described with reference to FIG.
[0017]
Now, it is assumed that the exposure control unit in the camera CPU 105 sets the exposure at the light transmittance of 50% and the shutter speed ST1 based on the signal from the photometry unit 107. Then, based on the setting information, in the present embodiment, after detecting the ON of the second stage SW2 of the release means 102, the voltage application is started after a lapse of a predetermined minute time t 'such as an initial setting, etc. Exposure is started after a lapse of time t ". The values of t 'and t" are processing times and are almost fixed.
In the figure, both t 'and t "are shown in an enlarged manner than the actual time.
[0018]
The voltage applied to the EC element is set based on information stored in the storage unit. Actually, the average light transmittance during the exposure time at this applied voltage is controlled so as to be the same as the set light transmittance. In the present embodiment, the applied voltage data of 3 V is read from the storage unit 132 based on the set exposure condition, and the voltage is controlled by this voltage.
[0019]
Since the relationship between the average light transmittance and the set light transmittance is a relationship between the amount of light reaching the image sensor, the area enclosed by ST1 and the line of the change in the light transmittance of the set voltage (lower left) in FIG. It is controlled by selecting an applied voltage that has the relationship between the set light transmittance and the area surrounded by ST1 (hatched part falling rightward) and the set light transmittance, and this area is the same. Therefore, if the exposure time is different, the applied voltage is different. For example, when the light transmittance is the same 50% and the shutter speed is ST2, the set voltage is 2V.
As described above, the light transmittance changes during the exposure, but the depth of field does not change like a diaphragm having a different aperture diameter, so that the change in the light transmittance has little effect on the photographing result. Therefore, the light amount at the end of the exposure is the same as that in the case of the photographing in which the light transmittance does not change.
[0020]
However, this can be applied when light uniformly reaches the image sensor 109 in the same time zone.For example, when a high shutter speed is set, not all the pixels of the image sensor are exposed during exposure. Then, the slit-shaped shutter opening moves, and a temporal shift occurs in the pixels. Therefore, if the above-described change in light transmittance occurs during exposure, unevenness occurs in the exposure result in the direction of passage through the slit-shaped shutter opening. Therefore, in the present embodiment, this control is not performed when a shutter speed higher than the shutter speed of the so-called X contact tuning speed, which is a slit-shaped shutter opening, is set.
[0021]
The operation of the control described above will be described with reference to the flowchart of FIG. It should be noted that control sections relating to focus driving, display means, setting means, and the like are not described in this flowchart because they are the same as in the related art.
First, in S301, it is determined whether or not the first-stage SW1 of the release means 102 is ON. If not, the process waits. Thereafter, when the switch SW1 is turned on, the process proceeds to S302, in which the photometry is performed by the photometry unit 107 in the camera, and the result is output to the camera CPU 105. In step S303, an exposure time (hereinafter, referred to as a shutter speed) and a light transmittance (hereinafter, referred to as an aperture value) at the time of exposure are set based on the photometric information in step S302. Next, in S304, it is determined whether or not the set aperture value is in an open state with no change in light transmittance. If it is set in the open state (no change in light transmittance), the flow proceeds to S319. Otherwise, the process proceeds to S305. In S305, it is determined whether or not the shutter speed set in S303 is faster than a so-called X contact tuning speed at which a slit-shaped opening is formed. If it is faster, the process proceeds to S312, and if it is lower than the X contact tuning speed, the process proceeds to S306.
[0022]
In step S <b> 306, the lens CPU 137 reads information on the voltage applied to the EC element 141 stored in the storage unit 132 from the exposure conditions set by the camera CPU 105. In step S307, it is determined whether or not the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S308. If the switch SW2 is not ON, the process proceeds to step S301. In step S308, the voltage information applied to the EC element 141 extracted in step S306 is transmitted to the aperture driving unit 135 to start the operation of changing the light transmittance of the EC element 141. Then, in step S309, the shutter is opened to start exposure. Thereafter, the voltage is continuously applied to the EC element until the shutter is closed and the exposure is completed at S310 after the set shutter speed has elapsed, and the light transmittance changes as shown in FIG. After the exposure is completed in S310, in S311 a reverse voltage is applied for a predetermined time to restore the light transmittance of the EC element 141, and the EC element 141 is decolorized.
[0023]
If it is determined in step S305 that the shutter speed is faster than the X contact tuning speed, if the light transmittance of the EC element is changed during exposure, there is a possibility that the exposure result will be uneven. Therefore, control after step S312 is performed. In S312, the lens CPU 137 reads out the applied voltage information to the EC element 141 stored in the storage unit 132. The information read out at this time is applied voltage data in a stable light transmittance state unlike S306. In step S313, similarly to step S307, it is determined whether or not the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S314. If not, the process proceeds to step S301. stand by. In S314, the application of the voltage to the EC element 141 set in S312 is started as in S308. Thereafter, in step S315, the process waits until the time t0 until the light transmittance becomes stable, and after that, the shutter is opened and exposure is started in step S316. After elapse of the set shutter speed, the exposure is terminated in S317, and in S318, a reverse voltage is applied for a predetermined time as in S311 to decolor the EC element.
[0024]
If it is determined in step S304 that the aperture is open, the same control as in the related art is performed. In step S319, similarly to step S307, it is determined whether or not the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S320. If not, the process proceeds to step S301. stand by. In S320, the shutter is opened to start exposure. After the elapse of the set shutter speed, the exposure ends in S322, and the control ends.
It should be noted that the values of the X-contact tuning speed, t ', and t "in the present embodiment differ depending on the camera to be mounted, and the control may be performed based thereon.
[0025]
[Second embodiment]
Next, a second embodiment according to the present invention will be described.
FIG. 4 is a block diagram showing the second embodiment. The components in this figure are almost the same as those in FIG. 1 showing the first embodiment, and the same numbers indicate the same operations. The difference from FIG. 1 lies in the imaging element 120 and the storage means 160. In the present embodiment, the mechanical shutter mechanism is abolished, and instead, the image sensor 120 is an image sensor having an electronic shutter function, and exposure is performed by the electronic shutter function. The information on the EC element 141 stored in the storage unit 160 is information on a change in light transmittance of the EC element 141 when a predetermined voltage is applied, and in the present embodiment, the application time when 3 V is applied. Is stored.
[0026]
FIG. 5 is a diagram schematically illustrating a change in the light transmittance of the EC element of the light amount adjusting unit and a time chart related to exposure of the imaging apparatus according to the second embodiment. In the present embodiment, the voltage applied to the EC element 141 is a predetermined voltage of 3 V and is not changed. Further, the time T (i) from the time when the second-stage SW2 of the release means 102 is turned ON to the time when the voltage application to the EC element is started is fixed.
[0027]
Now, suppose that the exposure control means in the camera CPU 105 sets the exposure at the light transmittance of 50% and the shutter speed ST based on the signal from the photometry means 107. Then, in the present embodiment, the applied voltage data of 3 V is read from the storage unit 160 based on the set exposure condition, and the average light transmittance during the exposure time (the area surrounded by the line between the shutter speed ST and the change in light transmittance; The light transmittance at which a constant value of light transmittance becomes equal to the area enclosed between the STs is calculated and obtained), and the exposure start time t1 is controlled so as to be the same as the set light transmittance. ing.
[0028]
In the present embodiment, the voltage application is started after a predetermined time T (i) has elapsed after detecting the ON of the second-stage SW2 of the release means 102. Therefore, depending on the set aperture value (light transmittance), a voltage may be applied to the EC element after the start of exposure. As described above, the light transmittance changes during the exposure, but the depth of field does not change like a diaphragm having a different aperture diameter, so that the change in the light transmittance has little effect on the photographing result. Therefore, the light amount at the end of the exposure is the same as that in the case of the photographing in which the light transmittance does not change.
By performing the above control, the release time lag is further reduced, and the storage capacity of the storage unit 160 is reduced. In the present embodiment, since the electronic shutter function provided in the image sensor 120 is used for the exposure time, control relating to exposure unevenness is not required.
[0029]
The control operation of the second embodiment described above will be described with reference to the flowchart of FIG. It should be noted that control sections relating to focus driving, display means, setting means, and the like are not described in this flowchart because they are the same as in the related art.
First, in S601, it is determined whether or not the first-stage SW1 of the release means 102 is ON. If not, the process waits. After that, when the switch SW1 is turned on, the process proceeds to S602, in which the photometry is performed by the photometry unit 107 in the camera, and the result is output to the camera CPU 105. In step S603, an exposure time (hereinafter, referred to as a shutter speed) and a light transmittance (hereinafter, referred to as an aperture value) during exposure are set based on the photometric information in step S602. Next, in S604, it is determined whether or not the set aperture value is in an aperture open state without a change in light transmittance. If the aperture value is set in an open state (no change in light transmittance), the flow proceeds to S623. Otherwise, the process proceeds to S605.
[0030]
In step S605, the lens CPU 137 reads out the light transmittance change information of the EC element 141 stored in the storage unit 160 from the exposure condition set by the camera CPU 105, and the exposure start time t1 is calculated by the camera CPU 105. In S606, it is determined whether or not the calculated t1 is shorter than the time T (i) until the voltage is applied to the EC element 141. If shorter, the process proceeds to S607, and if not, the process proceeds to S615.
[0031]
In step S607, it is determined whether or not the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S608. If the switch SW2 is not ON, the process proceeds to step S601. In S608, the timer is started to start counting t1 and T (i). In S609, it is determined whether or not the time t1 has elapsed. After the elapse of t1, the image sensor starts exposure in S610. In step S611, it is determined whether or not a time T (i) has elapsed. After the time T (i) has elapsed, the diaphragm driving unit 135 applies a predetermined voltage (3 V) to the EC element 141 in step S612. Then, in S613 after the set shutter speed has elapsed, the exposure is completed by the electronic shutter function. During this time, the voltage application to the EC element is continuously performed, and the light transmittance changes as shown in FIG. In step S614, a reverse voltage is applied for a predetermined period of time to restore the light transmittance of the EC element 141 to the original state, and the EC element 141 is decolorized.
[0032]
If t1 is not shorter than T (i) in S606, control from S615 is performed. In step S615, similarly to step S607, it is determined whether or not the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S616. If the switch SW2 is not ON, the process proceeds to step S601. stand by. In S616, the timer is started to start counting t1 and T (i). In step S617, it is determined whether or not the time T (i) has elapsed. After the elapse of T (i), the diaphragm driving unit 135 applies a predetermined voltage (3V) to the EC element 141 in step S618. In step S619, it is determined whether or not the time t1 has elapsed. After the time t1 has elapsed, the image sensor starts exposure in step S620. Then, in S621 after the elapse of the set shutter speed, the exposure is completed by the electronic shutter function. During this time, voltage application to the EC element is continuously performed. In step S622, a reverse voltage is applied for a predetermined period of time to restore the light transmittance of the EC element 141, and the EC element 141 is decolorized.
[0033]
If it is determined in step S604 that the aperture is open, control similar to that in the related art is performed. In step S624, similarly to step S607, it is determined whether or not the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S624. If not, the process proceeds to step S601. stand by. In S624, exposure is started by the image sensor. After the elapse of the set shutter speed, the exposure ends in S625, and the control ends.
[0034]
[Third Embodiment]
FIG. 7 is a diagram schematically showing a change in light transmittance of an EC element of a light amount adjusting unit and a time chart relating to exposure of an image pickup apparatus according to a third embodiment of the present invention. In the present embodiment, the image sensor has an electronic shutter function as in the second embodiment. Therefore, the symbols representing the components are the same as those in FIG. The voltage applied to the EC element 141 is a predetermined voltage of 3 V and is not changed. Further, the exposure start time T (r) from the ON of the second-stage SW2 of the release means 102 is fixed.
[0035]
Now, suppose that the exposure control means in the camera CPU 105 sets the exposure at the light transmittance of 50% and the shutter speed ST based on the signal from the photometry means 107. Then, in the present embodiment, the applied voltage data of 3 V is read from the storage unit 160 based on the set exposure condition, and the average light transmittance during the exposure time (the area surrounded by the line between the shutter speed ST and the change in light transmittance; The application start time t2 to the EC element is set such that the constant light transmittance and the constant light transmittance at which the area enclosed between the STs becomes equal are calculated and obtained). It is done by controlling.
[0036]
In the present embodiment, the exposure is started after a predetermined time T (r) has elapsed after the ON of the second-stage SW2 of the release means 102 is detected. Therefore, depending on the set aperture value (light transmittance), a voltage may be applied to the EC element after the start of exposure. As described above, the light transmittance changes during the exposure, but the depth of field does not change like a diaphragm having a different aperture diameter, so that the change in the light transmittance has little effect on the photographing result. Therefore, the light amount at the end of the exposure is the same as that in the case of the photographing in which the light transmittance does not change. By performing the above control, the time from SW2 being turned ON to the start of exposure is constant, so that the shooting timing is hard to be out of order, shooting chances are not easily missed, and the storage capacity of the storage unit 160 is reduced. Further, in the present embodiment, since the electronic shutter function provided in the image sensor 120 is used for the exposure time, there is no need to control exposure unevenness.
[0037]
The control operation of the third embodiment described above will be described with reference to the flowchart of FIG. It should be noted that control sections relating to focus driving, display means, setting means, and the like are not described in this flowchart because they are the same as in the related art.
First, in S801, it is determined whether or not the first-stage SW1 of the release means 102 is ON. If not, the process waits. Thereafter, when the switch SW1 is turned on, the process proceeds to S802, in which the photometry is performed by the photometry unit 107 in the camera, and the result is output to the camera CPU 105. In step S803, an exposure time (hereinafter, referred to as a shutter speed) and a light transmittance (hereinafter, referred to as an aperture value) at the time of exposure are set based on the photometric information in step S802. Next, in S804, it is determined whether or not the set aperture value is in the aperture open state without a change in light transmittance. If the aperture value is set in the open state (no change in light transmittance), the flow proceeds to S823. Otherwise, the process proceeds to S805.
[0038]
In step S805, the lens CPU 137 reads out the light transmittance change information of the EC element 141 stored in the storage unit 160 from the exposure condition set by the camera CPU 105, and determines the voltage application start time t2 to the EC element 141 by the camera CPU 105. Calculate. In S806, it is determined whether or not the calculated t2 is shorter than the time T (r) until the start of exposure. If shorter, the process proceeds to S807, and if not, the process proceeds to S815.
[0039]
In step S807, it is determined whether or not the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S808. If the switch SW2 is not ON, the process proceeds to step S801. In S808, the timer is started to start counting t1 and T (i). In step S809, it is determined whether or not the time t2 has elapsed. After the time t2 elapses, in step S810, the aperture driving unit 135 applies a predetermined voltage (3 V) to the EC element 141. Then, in step S811, it is determined whether or not the time T (r) has elapsed, and after the time T (r) has elapsed, exposure is started in the image sensor in step S812. In S813 after the set shutter speed has elapsed, the exposure is completed by the electronic shutter function. During this time, the voltage application to the EC element is continuously performed, and the light transmittance changes as shown in FIG. In step S814, a reverse voltage is applied for a predetermined time to restore the light transmittance of the EC element 141, and the EC element 141 is decolorized.
[0040]
If t2 is not shorter than T (r) in S806, control from S815 is performed. In step S815, similarly to step S807, it is determined whether the second-stage SW2 of the release unit 102 is ON. If the switch SW2 is ON, the process proceeds to step S816. If not, the process proceeds to step S801. stand by. In S816, the timer is started to start counting t2 and T (r). In S817, it is determined whether or not the time T (r) has elapsed, and after the elapse of T (r), exposure is started by the image sensor in S818. In S819, it is determined whether or not the time has elapsed after t2. After the elapse of t2, the aperture driving unit 135 applies a predetermined voltage (3 V) to the EC element 141 in S820. In S821 after the set shutter speed has elapsed, the exposure is completed by the electronic shutter function. During this time, voltage application to the EC element is continuously performed. In S822, a reverse voltage is applied for a predetermined period of time to restore the light transmittance of the EC element 141, and the EC element 141 is decolorized.
[0041]
If it is determined in step S804 that the aperture is open, the same control as in the related art is performed. In S824, similarly to S807, it is determined whether or not the second-stage SW2 of the release means 102 is ON. If the switch SW2 is ON, the process proceeds to S824. If not, the process proceeds to S801. stand by. In S824, exposure is started by the image sensor. After the elapse of the set shutter speed, the exposure ends in S825, and the control ends.
[0042]
The three embodiments have been described above. For example, the same effect can be obtained even if the control after S312 is omitted by using the image pickup device with the electronic shutter function in the first embodiment. Further, the second embodiment and the third embodiment may be combined and switched according to the shooting conditions. Needless to say, the present invention may be applied to an imaging device in which a camera and a lens are integrally configured.
[0043]
【The invention's effect】
According to the present invention, a release time lag can be reduced, accurate exposure control can be performed, and an imaging device that does not miss a shooting opportunity can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram schematically illustrating a change in light transmittance and a time chart regarding exposure according to the first embodiment.
FIG. 3 is a flowchart showing an operation of the first embodiment.
FIG. 4 is a block diagram showing a second embodiment.
FIG. 5 is a diagram schematically illustrating a change in light transmittance and a time chart regarding exposure according to a second embodiment.
FIG. 6 is a flowchart illustrating the operation of the second embodiment.
FIG. 7 is a diagram schematically illustrating a light transmittance change and a time chart related to exposure according to a third embodiment.
FIG. 8 is a flowchart showing an operation of the third embodiment.
FIG. 9 is a diagram showing a configuration of an electrochromic element for explaining a conventional technique.
FIG. 10 is a diagram illustrating response characteristics of an electrochromic element for explaining a conventional technique.
[Explanation of symbols]
105: Camera CPU
109: imaging means as an imaging element
110: shutter means
132: storage means
137: Lens CPU
141: Electrochromic element

Claims (9)

In an imaging apparatus having a light amount adjusting unit using a physical element capable of changing light transmittance, and an exposure control unit for setting an exposure time and a light transmittance of the light amount adjusting unit,
Storage means for storing information on the physical element in advance, and control means for controlling light transmittance by the light amount adjusting means based on the information on the physical element stored in the storage means. Imaging device. The control means for controlling the light transmittance by the light quantity adjusting means, during the exposure time set by the exposure control means, the average light transmittance of the light quantity adjusting means to the light transmittance set by the exposure control means The imaging apparatus according to claim 1, wherein the imaging apparatus is a unit that controls the imaging apparatus to perform the control. The light amount adjusting means is a light amount adjusting means using a physical element whose light transmittance changes by applying a voltage,
The control means for controlling the light transmittance by the light quantity adjusting means, during the exposure time set by the exposure control means, the average light transmittance of the light quantity adjusting means to the light transmittance set by the exposure control means 2. The image pickup apparatus according to claim 1, further comprising means for controlling a voltage applied to said light amount adjusting means in accordance with an exposure time set by said exposure control means. The storage unit is a storage unit that stores information about a change in light transmittance with respect to an application time for each applied voltage to the light amount adjustment unit,
The control means for controlling the light transmittance by the light quantity adjusting means is means for controlling the light transmittance by the light quantity adjusting means based on information stored in the storage means. Imaging device. The light amount adjusting means is a light amount adjusting means using a physical element whose light transmittance changes by applying a voltage,
2. The imaging apparatus according to claim 1, wherein the control unit that controls light transmittance by the light amount adjustment unit is a unit that changes an exposure start time according to an exposure time set by the exposure control unit. 3. . 6. The apparatus according to claim 5, further comprising: means for determining whether or not the exposure time set by the exposure control means is earlier than a predetermined time, and controlling the exposure start time to be changed based on the result of the determination. Imaging device. Means for changing the exposure start time according to the exposure time, during the exposure time set by the exposure control means, the average light transmittance of the light amount adjustment means to the light transmittance set by the exposure control means 6. The imaging apparatus according to claim 5, wherein the control unit controls the exposure start time according to the exposure time. The light amount adjusting means is a light amount adjusting means using a physical element whose light transmittance changes by applying a voltage,
The control means for controlling the light transmittance by the light quantity adjusting means, during the exposure time set by the exposure control means, the average light transmittance of the light quantity adjusting means to the light transmittance set by the exposure control means 2. The image pickup apparatus according to claim 1, wherein the control unit controls a voltage application start time to the light amount control unit according to an exposure time. The imaging device according to claim 1, wherein the physical element is an electrochromic element.

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