JP5230235B2 - Imaging apparatus and control method thereof - Google Patents

Description

  The present invention relates to an aperture and gain control when a push iris switch is pressed in a manual mode with an auto gain operation in an imaging apparatus.

  In professional video cameras, many users manually set aperture, shutter, and gain exposure parameters and shoot with manual exposure control.

  In addition, there is a demand for handling a sudden exposure change while performing manual exposure control, and a demand for easily controlling the exposure to near the proper exposure.

  Therefore, a push iris function is often used as an exposure change function during manual exposure control. This is because even if manual exposure control is performed, the aperture is automatically driven so that the exposure is appropriate only while the button is pressed, and if the button is stopped, it is fixed at the current aperture. It is an exposure change function that returns to normal manual exposure control.

  With this function, it is possible to easily adjust the exposure while maintaining manual exposure control without switching the mode of automatic exposure (hereinafter referred to as AE) by setting.

  The state of the operation of the imaging apparatus at this time will be described with reference to the block diagram of FIG.

  FIG. 7 is a block diagram showing a configuration of an imaging apparatus of a conventional example of the present invention.

  Reference numeral 110 denotes a lens, 120 an aperture (mechanism) that adjusts the amount of incident light, 130 an aperture drive motor that drives the aperture 120, and 140 an aperture mechanism drive device that drives the aperture drive motor 130. Reference numeral 150 denotes an aperture position detection device that detects the position of the aperture 120, and reference numeral 200 denotes an image sensor such as a CCD sensor that photoelectrically converts incident light.

  210 is an image sensor control device that controls the image sensor 200 and reads photoelectrically converted electrical signals, and controls a so-called electronic shutter function that controls the signal accumulation time. 220 is a sample of signals photoelectrically converted by the image sensor 200. Sample hold device.

  Reference numeral 230 denotes a programmable gain amplifier (hereinafter referred to as PGA) that can electrically amplify the output signal of the sample hold device 220 by applying a gain.

  An analog-digital converter 240 (hereinafter referred to as an A / D converter) converts an analog signal output from the PGA 230 into a digital signal.

  Reference numeral 250 denotes a signal processing device (hereinafter referred to as a control function) for generating a standard television signal by adding a synchronization signal after performing processing such as gamma correction, color separation, and color difference matrix on the output signal of the A / D converter 240. (Referred to as DSP).

  260 is a memory for storing images processed by the DSP 250, 270 is a recording medium capable of recording moving images and still images, and 300 is a microcomputer (hereinafter referred to as a microcomputer) that issues processing instructions to the DSP 250. is there. Reference numeral 280 denotes a display device such as a liquid crystal for displaying an image.

  Furthermore, the DSP 250 includes a luminance value acquisition device 251 that receives data output from the A / D converter 240 and obtains photometric knowledge of each pixel.

  Reference numeral 301 denotes a photometric value calculation device that calculates a photometric value for determining whether or not a captured image is in an appropriate exposure state from the luminance value output from the luminance value acquisition device 251, and 305 controls gain control. This is a gain control switching device for switching between manual and automatic.

  320 is an AE mode switching device that switches between the automatic exposure control mode and the manual exposure control mode, and 306 is a shutter control that switches whether the shutter is controlled manually or automatically according to the exposure control mode determined by the AE mode switching device. It is a switching device.

  Reference numeral 307 denotes an aperture control switching device that switches between manual and automatic aperture control according to the mode determined by the AE mode switching device.

  Reference numeral 311 denotes a manual gain control device for determining which gain value to manually determine when the output of the gain control switching device 305 indicates manual.

  Reference numeral 312 denotes a manual shutter control device for determining which shutter speed value to manually determine when the output of the shutter control switching device 306 indicates manual.

  Reference numeral 313 denotes a manual aperture control device for determining which aperture value to manually determine when the output of the aperture control switching device 307 indicates manual.

  Reference numeral 302 denotes a gain operation amount that calculates a gain control amount based on an output result of the manual gain control device 311 and outputs an operation command to the PGA 230 if the gain control is automatic based on the output of the photometric value calculation device 301. It is a calculation device.

  A shutter control amount 303 is calculated based on the output of the photometric value calculation device 301 if the shutter control is automatic, and based on the output result of the manual shutter control device 312 if the shutter control is manual. The shutter operation amount calculation device

  304 calculates an aperture control amount based on the output of the photometric value calculation device 301 if the aperture control is automatic, and based on the output result of the manual aperture device 313 if the aperture control is manual, and issues an operation command to the aperture mechanism driving device 140. This is a diaphragm drive amount calculation device to be output.

  Even if 330 is set so that the control of the aperture 120 is performed manually, the aperture control amount calculation device 304 forcibly calculates the aperture control amount only while it is depressed, and the photometric value calculation device 301. This is a push iris switch that is performed based on the output of

  That is, even if the aperture 120 is set to be controlled manually, the aperture 120 is automatically controlled while the push iris switch is pressed.

  As described above, exposure control in a professional video camera is often performed manually.

  At this time, the manual exposure control mode is selected by the AE mode switching device 320, and the shutter control switching device 306 and the aperture control switching device 307 operate manually with respect to the shutter operation amount calculation device 303 and the aperture drive amount calculation device 304. I give an order to do.

  The gain switching control device 305 is instructed to manually operate the gain operation amount calculation device 302.

  It is assumed that the exposure control parameter values at this time are set to an aperture value F4.0, a shutter speed value 1/60 seconds, and a gain value 0 dB, respectively, and the exposure is appropriate.

  Here, when the brightness of the subject changes and the exposure state of the screen becomes brighter than the appropriate exposure by 0.5 Ev, the aperture value is set to F4. It is necessary to narrow down to 0.5 Ev by setting it to 8.

  However, since the user does not know how much to reduce to make it appropriate, that is, the amount of change in the brightness of the subject is 0.5 Ev, the brightness of the main subject is displayed on the display device using a histogram or the like. I will narrow down the aperture while checking.

  That is, while manually controlling the aperture 120, it can be known that the amount of change in the brightness of the subject is 0.5 Ev and the appropriate aperture value is F4.8.

  In a professional video camera that often controls zoom operation and focus operation manually, it is very troublesome to perform this operation every time the brightness of the subject changes.

  Therefore, if the push iris switch 330 is used, even if the manual exposure control mode is set, the aperture control is automatically performed so as to obtain an appropriate exposure only while the push iris switch 330 is pressed.

  In this way, by using the push iris switch 330, in the manual exposure control mode, even when the brightness of the subject changes, it is possible to concentrate on zooming and focusing operations while maintaining proper exposure. Less.

  As described above, there is a proposal to use the diaphragm by switching between the fixed control and the automatic control (see Patent Document 1).

  As described above, in addition to the method of making the exposure appropriate by automatically performing only the aperture control as appropriate, depending on the user, the aperture control and the shutter control are fixed, and the exposure is appropriately controlled by automatically controlling the gain. There is also a request.

  Specifically, this is the case as follows.

  If the aperture value changes, the depth of field changes and the focus is out of focus, or it becomes difficult to focus manually due to the change in depth of field.

  Therefore, the aperture is reduced and fixed to some extent, that is, the depth of field is increased and fixed.

  For example, if the open aperture value is F1.6, it is fixed at F5.6 or the like. Since it is not desired to change the frame rate during moving image shooting, the shutter speed value is fixed to a certain value (for example, 1/60 seconds).

  In such a setting and in a scene where the main subject is a moving object or person and the way the light source hits the main subject changes, if you want to keep the main subject at an appropriate exposure, by automatically controlling the gain, There is a demand for shooting with proper exposure.

  In such shooting, if the exposure does not change greatly, but the exposure changes only slightly, the S / N ratio does not change greatly even if exposure control is performed with gain, so the gain is automatically controlled. Thus, the exposure may be kept appropriate.

  However, if the exposure is properly controlled by automatically controlling the gain, if the weather or lighting conditions change suddenly and the brightness of the subject becomes much darker, the gain will increase significantly. The S / N ratio is significantly worse than what the user intended.

  In this way, when shooting is performed in a state where the S / N ratio is poor, the user needs to improve the S / N ratio by applying noise reduction after shooting, which is time-consuming.

  Therefore, in order to save the trouble of editing after shooting, it is considered that the user needs to perform shooting in a state where the S / N ratio is not deteriorated as much as possible.

Therefore, when the aperture is narrower than fully open, the aperture is automatically driven to the open side by the push iris function to lower the gain that has been significantly increased to improve the S / N ratio or to achieve proper exposure. It is convenient if you can.
JP-A-6-205285

  However, since the push iris function is to drive the aperture so that the image being photographed has an appropriate exposure, the push iris function is provided when the gain is automatically controlled by the gain being automatically controlled. Even if the button is pressed, the iris is not driven.

  The present invention has been made in view of the above problems, and its purpose is to drive the aperture in a direction to open the aperture regardless of the photometric value when the push iris button is pressed during automatic gain control. This lowers the gain and improves the S / N ratio.

In order to achieve the above object, an imaging device of the present invention includes an imaging device that photoelectrically converts light incident from a lens, a photometric value calculation unit that calculates a photometric value from an electrical signal output from the imaging device, driving a throttle means, and amplifying means for electrically amplifying the output signal from the imaging device, the throttle hand stage on the basis of a photometric value output from the photometric value calculation means for adjusting the amount of light incident on the image sensor The first exposure control mode for controlling the exposure so that a predetermined exposure state is obtained, and the amplifying unit is operated based on the photometric value output from the photometric value calculating unit while fixing the position of the aperture unit. A second exposure control mode for performing exposure control so as to achieve the predetermined exposure state, and the exposure control mode of the exposure control means is changed to the first exposure control mode and the second exposure control mode. Dew A switching means for switching to the control mode, and
It said exposure control means fixes said throttle means in said second exposure control mode in a position other than the open end, and, to operate the amplifier hand stage based upon the photometric value output from the photometric value calculating means wherein after the case has been switched to the first exposure control mode of the switching means, by driving the throttle means to the open side when you're I line exposure control such that the predetermined exposure condition Te first The exposure control is performed by the exposure control mode .

  According to the present invention, it is possible to maintain a good image quality while providing a function for maintaining an appropriate exposure with a simple operation when a sudden scene change occurs without impairing the freedom of manual control. is there.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. However, the dimensions, shapes, relative arrangements, and the like of the components exemplified in the present embodiment should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to.

<First Embodiment>
FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus according to the first embodiment of the present invention.

  In addition, about the structure of an imaging device, about the structure similar to the prior art example shown in FIG. 7, the same code | symbol is attached | subjected and description is omitted.

  By depressing this switch 340, only the aperture 120 is driven based on the photometric value according to the setting state of the image pickup device to make exposure appropriate, or the aperture and the PGA are operated simultaneously to improve the S / N ratio. This is a push AE switch for making the exposure appropriate.

  In the present embodiment, the members are the same as those of the push iris switch 330 in FIG. 7 showing the conventional example, but the behavior of the imaging device when the switch is pressed is different.

  Reference numeral 402 denotes a gain operation amount calculation device, which has other functions in addition to the functions of the gain operation amount calculation device 302 in FIG.

  When the aperture value and shutter speed are fixedly controlled and the PGA is automatically controlled, the gain operation amount calculation device 402 responds to the output change amount of the aperture position detection device 150 when the push AE switch 340 is pressed. The gain operation amount is calculated and the PGA 230 is controlled.

  Reference numeral 404 denotes an aperture drive amount calculation device, which has other functions in addition to the functions of the aperture drive amount calculation device 304 in FIG.

  When the aperture value and the shutter speed are fixedly controlled and the gain is automatically controlled, the aperture drive amount calculation device 404 is configured to forcibly drive the aperture to the open side when the push AE switch 340 is pressed. A diaphragm driving amount is calculated, and the diaphragm mechanism driving device 140 is controlled.

  Here, the operation of the imaging apparatus when the AE mode switching device 320 is set to the manual mode and the push AE switch 340 is pressed will be described with reference to FIG.

  FIG. 2 is a diagram showing how the aperture and PGA operate when the push AE switch is pressed.

  In FIG. 2, on the far left, gain control settings by the gain control switching device 305 are classified as fixed control or automatic control.

  First, a description will be given when the gain control setting is fixed.

  When the gain control setting is fixed (patterns 1 and 2 in FIG. 2), the same operation as when the push iris switch 330 shown in the conventional example is pressed is performed.

  That is, the diaphragm 120 is driven based on the photometric value calculated by the photometric value calculating device 301. For example, when the aperture value is other than the value indicating the open end, the driving of the aperture 120 is automatically controlled if the exposure is under or over with respect to the appropriate value regardless of the gain value, and stopped when the exposure is appropriate. To do.

  Here, “automatic” means that the diaphragm 120 and the PGA 230 are operated in a direction to make the exposure appropriate based on the photometric value. The term “auto” described in FIG. 2 has the same meaning. Incidentally, the stop in FIG. 2 means not controlling.

  Next, explanation will be given when the gain control setting is automatic.

  When the aperture value indicates an open end and the gain value is 0 dB (pattern 3 in FIG. 2), only the gain is automatically controlled if the exposure is lower than the appropriate value, and only the aperture is automatically controlled if the exposure is over. If it is appropriate, stop the aperture and gain.

  That is, if the exposure is lower than appropriate, the gain is increased whether or not the push AE switch 340 is pressed.

  If the exposure is more than appropriate, the gain cannot be dealt with (it cannot be lowered below 0 dB), so the aperture is reduced as in the conventional example.

  When the aperture value indicates an open end and the gain value is 0 dB or more (pattern 4 in FIG. 2), only the gain is automatically controlled if the exposure is below or above the appropriate value, and the aperture and gain are adjusted if the exposure is appropriate. Stop both.

  That is, when the gain is increased and the exposure is more than appropriate, the first priority is to improve the S / N ratio, and the exposure is adjusted by lowering the gain without narrowing the aperture.

  When the exposure is lower than appropriate, the aperture is at the open end, so the exposure can only be adjusted with the gain, and the gain is increased.

  This operation is automatic gain control after all, and since the setting is already automatic gain control, the operation is the same whether or not the push AE switch 340 is pressed.

  When the aperture value is a value other than the open end and the gain value is 0 dB (pattern 5 in FIG. 2), the aperture is automatically controlled only when the exposure is under or over the appropriate value, and the aperture and gain are set when the exposure is appropriate. Together.

  In other words, when the aperture is set down, even if the gain control setting is automatic, the S / N ratio is given priority, so the gain is not increased even if the exposure is lower than appropriate, and the aperture is automatically controlled first. Adjust the exposure.

  Of course, if the exposure is more than appropriate, the aperture can only be reduced, and the exposure is adjusted by automatically controlling the aperture.

  That is, the operation is the same as when the conventional push iris button is pressed (pattern 2 in FIG. 2).

  When the aperture value is not a value indicating the open end and the gain value is 0 dB or more (pattern 6 in FIG. 2), this is a pattern that is a feature of the present invention, but the exposure is under, proper, or over than proper. Nevertheless, the diaphragm is driven to the open side at a certain speed.

  Then, the PGA 230 lowers the gain by the amount of light that the diaphragm has moved to the open side.

  That is, since the diaphragm is in an unbalanced state where the gain is increased, the diaphragm mechanism control circuit 140 operates to open the diaphragm for the purpose of improving the S / N ratio.

  At this time, instead of lowering the gain to improve the S / N ratio and automatically controlling the aperture based on the photometric value, or opening the aperture only for the reduced gain, the aperture is first opened. The reason why the gain is lowered by the amount opened is described below.

  First, FIG. 3 shows an operation in a case where the gain is lowered to improve the S / N ratio, and the aperture is automatically controlled based on the photometric value to obtain an appropriate exposure.

  In FIG. 3, the horizontal axis indicates time 1 V (16.6 ms), and the vertical axis indicates the aperture value and gain value.

  When the time is 0 V, the aperture value is narrowed down to F5.6, the gain is increased to 9 dB, and it is assumed that the exposure is appropriate at this time.

  Here, the push AE switch 340 is pressed, and the PGA 230 operates so that the gain goes to 0 dB at a constant speed according to the brightness.

  The diaphragm 120 is driven in the opening direction based on a photometric value obtained as a result of the PGA 230 moving toward 0 dB.

  However, since the gain value set by the PGA 230 is digital data, the value is immediately reflected when it is set.

  On the other hand, the change in the aperture value requires driving a member called an aperture blade, and the aperture control is servo-controlled by using a filter for stable driving. About 100 mS (6V) is required.

  In the present embodiment, it takes 6V to drive the diaphragm to the target position, but it does not necessarily take 6V, and there are some differences depending on the type of the diaphragm device.

  However, as long as a device called a diaphragm blade is driven, it still takes a predetermined time to drive physically.

  In other words, since the driving of the diaphragm is slower than the operation of adjusting the gain value by the PGA 230, the diaphragm cannot catch up with the gain operation.

  Even when the gain reaches 0 dB, the aperture is not yet driven to the target position for achieving proper exposure.

  The lower part of FIG. 3 shows the exposure state by the operation of the PGA and the diaphragm in this case.

  The horizontal axis is time as in the upper diagram of FIG. 3, and has the same scale as the time axis of the upper diagram. The vertical axis indicates the brightness of the screen, that is, the exposure state.

  According to the figure, it can be seen that the exposure continues to be underexposed until the gain reaches 0 dB, and the screen becomes darker.

  Then, after the gain reaches 0 dB, the brightness of the screen gradually increases and approaches the appropriate exposure.

  Such a change in the exposure state is not preferable for a moving image expressed as a continuous image.

  Next, FIG. 4 shows the operation when the gain is lowered to improve the S / N ratio, and the aperture is opened by the amount of the gain to achieve proper exposure.

  The meanings of the horizontal and vertical axes in FIG. 4 and the initial states of the aperture, gain, and exposure are the same as those described with reference to FIG.

  When the push AE switch 340 is pressed, the PGA 230 operates toward 0 dB at a constant speed according to the brightness.

  The aperture drive amount calculation device 404 sets a target aperture value according to the amount of gain change 2 V after the PGA 230 starts to operate, and instructs the aperture mechanism drive device 140 to drive the aperture.

  In the present embodiment, the target aperture value is determined according to the amount of gain change after 2V, but the amount of gain change may be calculated for every 1V that is the minimum control unit.

  The smaller the gain change amount calculation interval, the shorter the time until the diaphragm starts to move, and the higher the accuracy of the control result.

  This gain change amount is the amount indicated as (1) attached to the operation part of the PGA 230 in FIG.

  First, the aperture drive amount calculation device 404 issues a command to the aperture drive device 140 so as to open the aperture from F5.6 by the amount of light corresponding to the amount of gain change shown in (1).

  As described above, since it takes about 6V to drive the aperture to the target position, it takes 6V to drive the aperture by the amount of light corresponding to the amount of gain change shown in (1). .

  In the meantime, the PGA 230 continues to operate at a constant speed.

  When the diaphragm finishes driving by the amount of light corresponding to the amount of gain change shown in (1), the amount of gain change shown in (2) is referred to.

  Next, the aperture drive amount calculation device 404 issues a command to the aperture drive device 140 to open the aperture by the amount of light corresponding to the amount of gain change shown in (2).

  After 6V, when the driving is completed by the amount of light corresponding to the amount of change in gain shown in (2), the operation amount of the next PGA 230 is referred to.

  This operation is repeated until the gain becomes 0 dB or the aperture is opened.

  In order to drive the aperture at regular intervals in this manner, as shown in the lower graph of FIG. 4, the exposure state remains under and repeats being under or more relaxed.

  Similar to the change in the exposure state shown in FIG. 3, such a change in the exposure state is unnatural and undesirable for a moving image.

  As described above, it can be seen from the state of transition of the exposure state shown in FIGS. 3 and 4 that the exposure state cannot be stabilized by the method of operating the aperture 120 after operating the PGA 230 with priority.

  This is because the driving speed of the diaphragm 120 is overwhelmingly slower than the operating speed of the PGA 230 as described above.

  In order to solve this problem, it is effective to first drive the aperture to the open side at a constant speed and lower the gain by the amount of light increased by driving the aperture.

  FIG. 5 shows an operation in which the aperture is driven to the open side at a constant speed, and the gain is lowered by an amount corresponding to the amount of light increased by driving the aperture to achieve proper exposure.

  The meanings of the horizontal and vertical axes in FIG. 5 and the initial states of the aperture, gain, and exposure are the same as those described with reference to FIG.

  When the push AE switch 340 is pressed, the diaphragm 120 is driven toward the open side at a constant speed with respect to the brightness.

  A diaphragm drive amount 1 V after the diaphragm 120 starts to be driven can be obtained based on an output from the diaphragm position detection device 150.

  The amount of change in the aperture is the amount indicated by (1) attached to the drive portion of the aperture in FIG.

  Thereafter, the gain value is lowered from 9 dB by the amount of light corresponding to the driving amount of the diaphragm shown in (1).

  As described above, since the change of the gain value is set and immediately reflected, the time until the target gain value is reached is 1 V which is the minimum control unit.

  Therefore, a gain corresponding to the driving amount of the diaphragm can be set for each 1V. This operation is repeated every V until the gain becomes 0 dB or the aperture is opened.

  Thus, since the PGA 230 can be operated every V according to the drive of the diaphragm 120, as shown in the lower graph of FIG. 5, the exposure state is the first shown in (1) until the gain becomes 0 dB. It remains under as much as the drive amount of the aperture for 1V.

  The exposure state shown in FIG. 5 is closer to the appropriate exposure than the exposure states shown in FIGS. 3 and 4 and is a stable exposure state, so it can be said that the exposure state is more preferable as a moving image.

  As described above, the operation method of the aperture and the gain has been shown in three examples. As described above, the gain is decreased in order to improve the S / N ratio and the aperture is automatically controlled according to the photometric value, and the gain is increased. If the aperture is opened by the lowered amount, the exposure state becomes unstable.

  Therefore, it is unsuitable as a method of operating the aperture and gain during moving image shooting.

  On the other hand, with regard to the control method for operating the PGA by the amount of opening of the aperture after opening the aperture, the exposure state is more stable than the above-described aperture and PGA operation methods. It is suitable as an operation method.

  Next, FIG. 6 shows the features of the present invention described above. The operation of the diaphragm and the PGA when the push AE switch is pressed when the diaphragm and the shutter are fixed and the PGA is automatically controlled. The flowchart about is shown.

  When the image pickup apparatus is turned on, the image pickup apparatus prepares for a process starting from step S101.

  In step S <b> 101, it is determined whether the diaphragm 120 and the shutter control are fixed control by selecting the manual mode by the AE mode switching device 320.

  If the control of the diaphragm 120 and the shutter is fixed control in step S101, the microcomputer 300 advances the process to step S102.

In step S101, if the AE mode is not the manual mode and the control of either the aperture 120 or the shutter is automatic control, the push AE switch 340 becomes invalid, and thus this processing ends.

  In step S102, the microcomputer 300 determines whether or not the push AE switch 340 is pressed. If it is determined that the push AE switch 340 is pressed, the process proceeds to step S103.

  If the microcomputer 300 determines in step S102 that the push AE switch has not been pressed, the process ends.

  In step S103, the microcomputer 300 determines whether or not the gain control by the PGA 230 is in a mode that is automatically controlled based on the photometric value by the gain control switching device 305. Proceed to step S104.

  If the microcomputer 300 determines in step S103 that the gain control by the PGA 230 is fixed control, the microcomputer 300 advances the process to step S201.

  In step S201, the push iris operation shown in the conventional example is executed.

  Specifically, the exposure is controlled based on the photometric value only by driving the aperture 120.

  Then, the microcomputer 300 returns the process to step S102 and starts determining whether or not the push AE switch is pressed.

  In step S <b> 104, the microcomputer 300 determines whether the diaphragm 120 is located at the open end based on the output from the diaphragm position detection device 150.

  If the microcomputer 300 determines in step S104 that the diaphragm 120 is located at the open end, the process proceeds to step S301. If the microcomputer 300 determines that the diaphragm 120 is located in a position other than the open end, the process proceeds to step S105.

  In step S301, the microcomputer 300 determines whether or not the gain is higher than 0 dB.

  If the microcomputer 300 determines in step S301 that the gain is greater than 0 dB, the process proceeds to step S302. If the microcomputer 300 determines that the gain is 0 dB, the process proceeds to step S303.

  In step S302, the microcomputer 300 performs exposure control only by the operation of the PGA 230 based on the photometric value, returns the process to step S102, and starts determining whether or not the push AE switch is pressed.

  In step S303, the microcomputer 300 performs exposure control by changing the aperture 120 or the PGA 230 based on the photometric value, returns the process to step S102, and starts determining whether or not the push AE switch is pressed.

  In step S105, the microcomputer 300 determines whether or not the gain is higher than 0 dB.

In step S105, the microcomputer 300, if it is determined gain and 0dB larger, the process proceeds to step S 106, if determined that the gain is 0dB, the process proceeds to step S 109.

  In step S109, the microcomputer 300 performs exposure control by driving only the diaphragm 120 based on the photometric value, returns the process to step S102, and starts determining whether or not the push AE switch is pressed.

  In step S106, the microcomputer 300 drives the diaphragm 120 to the open side at a constant speed regardless of the photometric value, and proceeds to step S107.

  In step S107, the microcomputer 300 refers to the drive amount of the diaphragm 120 driven in step S106, and advances the process to step S108.

  In step S108, the microcomputer 300 reduces the amplification factor by the brightness corresponding to the driving amount of the diaphragm 120 referred to in step S107, returns the process to step S102, and determines whether or not the push AE switch is pressed. Begin.

  As described above, according to the present invention, when the aperture is fixedly controlled and the gain is automatically controlled, when the exposure condition of the subject changes and the gain increases more than expected, the S / N It is possible to perform suitable exposure control without reducing the ratio.

  Specifically, by pushing the push AE switch, it is driven in the direction to open the aperture regardless of the photometric value, and the amplification factor is decreased by the brightness corresponding to the driving amount of the aperture. An effect of improving the ratio by an appropriate amount can be obtained.

1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment of the present invention. It is the figure which showed the mode of operation | movement of an aperture stop and PGA when a push AE switch is pressed down. In the imaging device which concerns on the 1st Embodiment of this invention, it is the figure which showed the operation | movement in the case of reducing a gain in order to improve S / N ratio, and controlling a diaphragm automatically based on a photometric value, and setting it to appropriate exposure. is there. In the imaging device which concerns on the 1st Embodiment of this invention, it is the figure which showed the operation | movement in the case of lowering | hanging a gain in order to improve S / N ratio, opening a diaphragm | stop by the part which reduced the gain, and making it appropriate exposure. is there. In the imaging apparatus according to the first embodiment of the present invention, the operation is shown in the case where the aperture is driven to the open side at a constant speed, and the gain is decreased by the amount of light increased by the driving of the aperture to achieve proper exposure. FIG. In the imaging apparatus according to the first embodiment of the present invention, when the aperture and the shutter are fixed and the PGA is automatically controlled, the operation of the aperture and the PGA when the push AE switch is pressed. A flowchart is shown. It is a block diagram which shows the structure of the imaging device of the prior art example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 Lens 120 Aperture mechanism 130 Aperture drive motor 140 Aperture mechanism drive device 150 Aperture position detection device 200 Image sensor 210 Image sensor drive device 220 Sample hold device 230 PGA
240 A / D converter 250 DSP
251 Luminance value acquisition device 260 Memory 270 Recording medium 280 Display device 300 Microcomputer 301 Photometric value calculation device 302 Gain operation amount calculation device 303 Electronic shutter operation amount calculation device 304 Aperture drive amount calculation device 305 Gain control switching device 306 Shutter control switching device 307 Aperture control switching device 311 Manual gain control device 312 Manual shutter control device 313 Manual aperture control device 320 AE mode switching device 330 Push iris switch 340 Push AE switch 402 Gain operation amount calculation device 404 Aperture drive amount calculation device

Claims (9)

An image sensor that photoelectrically converts light incident from the lens;
A photometric value calculating means for calculating a photometric value from the electrical signal output from the image sensor;
A diaphragm means for adjusting the amount of light incident on the image sensor;
Amplifying means for electrically amplifying an output signal from the image sensor;
A first exposure control mode that controls exposure to a predetermined exposure state by driving the throttle hand stage on the basis of a photometric value output from the photometric value calculation means, and fixing the position of said throttle means Exposure control means having a second exposure control mode for performing exposure control so that the amplifying means is operated based on a photometric value output from the photometric value calculating means to achieve the predetermined exposure state;
Switching means for switching the exposure control mode of the exposure control means between the first exposure control mode and the second exposure control mode ;
It said exposure control means fixes said throttle means in said second exposure control mode to a position other than the open end, and, to operate the amplifier hand stage on the basis of a photometric value output from the photometric value calculating means wherein after the case has been switched to the first exposure control mode of the switching means, by driving the throttle means to the open side when you're I line exposure control such that the predetermined exposure condition Te first An image pickup apparatus that performs exposure control in an exposure control mode . Said exposure control means, the said throttle means is fixed at a position other than the open end in the second exposure control mode, and by operating said amplifying means based on the photometric value output from the photometric value calculating means when switched to the first exposure control mode by said switching means exposure control such that the predetermined exposure state when you're I row, by driving the throttle means to the open side, the restrictor means The image pickup apparatus according to claim 1, wherein exposure control is performed in the first exposure control mode after a gain obtained by the amplifying unit is lowered in accordance with a driving amount. The exposure control means fixes the aperture means at a position other than an open end in the second exposure control mode, and operates the amplification means based on a photometric value output from the photometric value calculation means. When exposure control is performed so as to achieve the predetermined exposure state, when the switching means switches to the first exposure control mode, amplification by the amplifying means is started after the diaphragm means starts to be driven to the open side. The imaging apparatus according to claim 2, wherein the rate starts to decrease. The exposure control means fixes the aperture means at a position other than an open end in the second exposure control mode, and operates the amplification means based on a photometric value output from the photometric value calculation means. When exposure control is performed so as to achieve the predetermined exposure state, when the switching unit switches to the first exposure control mode, the diaphragm is not used regardless of the photometric value output from the photometric value calculating unit. 4. The image pickup apparatus according to claim 1, wherein the means is driven to the open side. The exposure control means fixes the aperture means at a position other than an open end in the second exposure control mode, and operates the amplification means based on a photometric value output from the photometric value calculation means. The amplifying means set in the first exposure control mode when the switching means switches to the first exposure control mode while performing exposure control so as to achieve the predetermined exposure state. The imaging apparatus according to claim 4, wherein the aperture means is driven to the open side in accordance with the amplification factor. The exposure control means fixes the aperture means at a position other than an open end in the second exposure control mode, and operates the amplification means based on a photometric value output from the photometric value calculation means. The amplifying means set in the first exposure control mode when the switching means switches to the first exposure control mode while performing exposure control so as to achieve the predetermined exposure state. The image pickup apparatus according to claim 5, wherein the diaphragm unit is driven until the open side position determined according to the amplification factor is obtained. The exposure control means fixes the aperture means at a position other than an open end in the second exposure control mode, and operates the amplification means based on a photometric value output from the photometric value calculation means. When the exposure control is performed so as to achieve the predetermined exposure state, when the switching means switches to the first exposure control mode, the aperture means is driven to the open side at a constant speed. The imaging device according to any one of claims 1 to 6. The exposure control means fixes the aperture means at a position other than an open end in the second exposure control mode, and operates the amplification means based on a photometric value output from the photometric value calculation means. When exposure control is performed so as to achieve the predetermined exposure state, when the switching means switches to the first exposure control mode, the aperture value is driven to the open side, and then the photometric value calculation means The image pickup apparatus according to claim 1, wherein exposure control in the first exposure mode is performed based on a photometric value output from the camera. An image sensor that photoelectrically converts light incident from a lens, a photometric value calculation unit that calculates a photometric value from an electrical signal output from the image sensor, a diaphragm unit that adjusts the amount of light incident on the image sensor, and the imaging performing an amplification means for electrically amplifying the output signal, the pre-Symbol exposure control photometry value by driving the throttle hand stage on the basis of a photometric value output from the calculation means to a predetermined exposure state from the device Exposure control is performed so that the predetermined exposure state is obtained by operating the amplifying unit based on the first exposure control mode and the photometric value output from the photometric value calculating unit while fixing the position of the aperture unit. A second exposure control mode, and an exposure control means comprising: an imaging device control method comprising:
A switching step of switching the exposure control mode of the exposure control means between the first exposure control mode and the second exposure control mode ;
Said exposure control means is fixed at a position other than the open end of said throttle means in said second exposure control mode, and by operating the amplifier hand stage on the basis of a photometric value output from the photometric value calculating means If the switch is switched to the first exposure control mode in step when Life has the exposure control so that the predetermined exposure conditions, the first from by driving the throttle means to the open side An exposure control step for performing exposure control in an exposure control mode .

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