IMAGING DEVICE AND IMAGING METHOD

An imaging device includes an imaging element and a processor receiving subject light and generating data, a lens cover, an illuminometer, a light source emitting illumination light, an actuator switching the lens cover between a first state for restricting the subject light from entering the imaging element and a second state for allowing the subject light to enter, a switch including a first filter preventing the illumination light from entering the imaging element and a second filter allowing the illumination light to enter, to place the first filter or the second filter on a front surface of the imaging element based on a brightness level in a surrounding environment detected by the illuminometer, and a setter setting an amplification factor to be used by the processor in generating the data based on a brightness level in the surrounding environment detected by the illuminometer in the first state.

RELATED APPLICATIONS

The present application claims priority to Japanese Application Number 2022-025855, filed Feb. 22, 2022, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

The present invention relates to an imaging device and an imaging method.

Description of the Background

Surveillance cameras are installed at various places such as nursing care facilities, hospitals, factories, and stores for crime and disaster prevention. Such surveillance cameras, which are imaging devices, are to be operated with privacy protection of individuals as subjects to be photographed. For privacy protection, a surveillance camera includes a light shield that covers a lens as appropriate.

Patent Literature 1 describes a camera that allows a light shield attached in front of a lens to be in an open or closed state in a manner recognizable from outside.

CITATION LIST

Patent Literature

BRIEF SUMMARY

However, the light shield switching from a closed state to an open state greatly changes light entering an imaging element, causing the imaging element to take more time to adjust sensitivity. This causes a delay before image data is generated with appropriate sensitivity after the light shield switches to the open state.

An imaging device according to an aspect of the present invention includes an imager that receives subject light through an opening in a housing and generates image data, a light shield between the opening and the imager to close the opening to restrict the subject light from entering the imager, a detector that detects a brightness level in a surrounding environment, an illumination light source that emits illumination light, a drive that switches the light shield between a first state in which the subject light is restricted from entering the imager and a second state in which the subject light is allowed to enter the imager, a switch including a first portion to prevent the illumination light from entering the imager and a second portion to allow the illumination light to enter the imager to place one of the first portion or the second portion on a front surface of the imager based on the brightness level in the surrounding environment detected by the detector, and a setter that sets an amplification factor to be used by the imager in generating the image data based on a brightness level in the surrounding environment detected by the detector in the first state.

An imaging method according to another aspect of the present invention includes receiving subject light through an opening in a housing with an imager and generating image data, detecting a brightness level in a surrounding environment, causing an illumination light source to emit illumination light, switching a light shield, located between the opening and the imager, between a first state in which the subject light is restricted from entering the imager and a second state in which the subject light is allowed to enter the imager, placing one of a first portion being a portion to prevent the illumination light from entering the imager or a second portion being a portion to allow the illumination light to enter the imager on a front surface of the imager based on the detected brightness level in the surrounding environment, and setting an amplification factor to be used in generating the image data based on a brightness level in the surrounding environment detected in the first state.

The technique according to the above aspects of the present invention shortens the time taken to generate image data with an appropriate amplification factor after the light shield switches to an open state.

DETAILED DESCRIPTION

An imaging device according to the present embodiment may be used for any purpose and may be installed, for example, at a hospital, a nursing care facility, a factory, and a store as a surveillance camera or a monitoring camera. The imaging device is switchable between an imaging state and an imaging-disabled state. More specifically, the imaging device can switch between a closed state in which light cannot enter an imaging optical system and an open state in which light can enter the imaging optical system. Once the imaging device switches to the imaging-disabled state (closed state), a person being imaged can recognize that the imaging device has been switched to the imaging-disabled state. The imaging device is switchable between a normal imaging mode and a low-light imaging mode based on the brightness level in the external environment surrounding the imaging device. The imaging in the normal imaging mode is performed using light incident on the imaging optical system when the external environment is bright. The imaging in the low-light imaging mode is performed using illumination light emitted when the external environment is dark to allow imaging of a subject using the illumination light.

FIGS.1and2are external views of an imaging device10.FIG.1is an external view of the imaging device10in the open state.FIG.2is an external view of the imaging device10in the closed state.FIG.3is an internal plan view of the imaging device10.

As shown inFIGS.1to3, the imaging device10includes a substantially rectangular housing12. The housing12has a front surface12aand side surfaces12c,12d,12e, and12fthat meet the sides of the front surface12a. Hereafter, the front surface12aof the housing12is referred to as being upward, the surface of the housing12opposite to the front surface12abeing downward, the side surface12cbeing frontward, the side surface12dbeing leftward, and the side surface12fbeing rightward.

The housing12has, in or on the front surface12a, a card slot24to receive a memory card48(refer toFIG.4) and an opening15, and illumination light sources161and162and an illuminometer17.

The illumination light sources161and162are, for example, light-emitting diodes (LEDs) that emit light with wavelengths in the infrared region (infrared rays or infrared light). In the low-light imaging mode (described later), the imaging device10emits infrared light from the illumination light sources161and162as illumination light to illuminate a subject.

The illuminometer17, which may be a photoresistor or a photodiode, is a detector that receives light from the surrounding environment (external environment) of the imaging device10and outputs a signal (luminance signal).

As shown inFIG.3, the housing12in the imaging device10accommodates a lens cover11, an imaging element13that is an image sensor such as a complementary metal-oxide semiconductor (CMOS) or a charge-coupled device (CCD), a lens14(imaging optical system) that focuses light from a subject (subject light) onto the imaging surface of the imaging element13, a switch18, and a control unit31. The lens cover11, the imaging element13, the lens14, and the switch18are arranged parallel to the front surface12a.

The opening15in the front surface12aof the housing12is on the optical axis of the lens14. Subject light passing through the opening15enters the imaging element13through the lens14(imaging optical system). The imaging element13receives subject light through the opening15in the housing12and outputs an image signal resulting from photoelectric conversion. An image processor35(refer toFIG.4), which is an image signal processor (ISP), described later processes the output image signal through various processes to generate image data. More specifically, the imaging element13and the image processor35function as an imager that receives subject light entering through the opening15in the front surface12aof the housing12and generates image data.

The lens cover11is located along the optical axis of the lens14between the lens14and the opening15to open or close the opening15. The lens cover11is movable either to an open position at which the opening15is open or to a closed position at which the opening is closed. The lens cover11moves on a plane orthogonal to the optical axis of the lens14(in other words, a plane parallel to the front surface12a). When the lens cover11moves to the open position, the lens cover11is away from the optical axis of the lens14to uncover the opening15on the optical axis of the lens14as shown inFIG.1(open state). This causes the lens14to be exposed through the opening15in the housing12to allow subject light to enter the imaging element13through the lens14.

When the lens cover11moves to the closed position, the lens cover11closes the opening15in the housing12as shown inFIG.2(closed state). This causes the lens cover11to cover the lens14to protect the lens14in the housing12. At the closed position shown inFIG.2, the lens cover11functions as a light shield that closes the opening15to restrict subject light from entering the imaging element13. The lens cover11is also referred to as a lens barrier or a shutter.

The switch18switches between the state in which no illumination light from the illumination light sources161and162is allowed to enter the imaging element13and the state in which illumination light is allowed to enter the imaging element13based on the brightness level (luminance) in the external environment of the imaging device10. More specifically, the switch18includes a first filter181, a second filter182, a holder183, and a drive assembly184. The first filter181is an infrared ray cut filter. The first filter181functions as a first portion that does not allow infrared light to enter the imaging element13. The second filter182is, for example, a dummy lens, and functions as a second portion that allows infrared light to enter the imaging element13.

The holder183holds the first filter181and the second filter182within a plane parallel to the front surface12a. The holder183holds the first filter181on the left and the second filter182on the right in the direction indicated by arrow AR shown inFIG.3. The holder183is movable in the direction indicated by arrow AR (in other words, the direction in which the first filter181and the second filter182are held). As the holder183moves along arrow AR, either the first filter181or the second filter182is placed on the optical axis of the lens14(in other words, the front surface of the imaging element13).

The drive assembly184includes, for example, a drive, such as a stepping motor or a gear coupler, and a guide such as a lead screw. The drive assembly184is thus connected to the holder183. When the drive assembly184is driven in response to a control signal from the control unit31(described later), the holder183connected to the drive assembly184moves along the plane parallel to the front surface12ain the direction indicated by arrow AR.

A substrate31ais a base for holding the imaging element13and the control unit31. The substrate31ais installed in a lower portion of the housing12.

The control unit31includes a central processing unit (CPU), a memory, and other components. The control unit31is a processor that may read and execute a control program prerecorded in a recording medium38(refer toFIG.4), such as a flash memory, to control various components of the imaging device10. The control unit31controls the components in the normal imaging mode or the low-light imaging mode in an imaging process to operate the components. The normal imaging mode is used when the external environment of the imaging device10is bright. The low-light imaging mode is used when the external environment of the imaging device10is dark and lacks a sufficient amount of light. In the low-light imaging mode, the imaging device10applies infrared light as illumination light and captures an image of the subject illuminated with the infrared light.

The processing performed by the control unit31will be described in detail later.

Control System for Imaging Device10

FIG.4is a block diagram of the control system in the imaging device10. As shown inFIG.4, the control unit31in the imaging device10includes a determiner32, an imaging controller33, a filter controller34, a setter36, a recording controller37, and the recording medium38.

The determiner32performs a determination process to determine whether the external environment surrounding the imaging device10is bright or dark based on a luminance signal output from the illuminometer17.

The imaging controller33controls driving of the imaging element13to cause the imaging element13to generate an image signal. The imaging controller33then performs the imaging process that causes the image processor35to generate image data based on the image signal. In imaging in the low-light imaging mode (described later), the imaging controller33supplies power to the illumination light sources161and162to cause infrared light to be output as illumination light.

Based on a determination result from the determiner32, the filter controller34controls movement of the holder183by driving the drive assembly184to place the first filter181or the second filter182on the optical axis of the lens14. In this case, the filter controller34places the first filter181that is an infrared ray cut filter on the optical axis of the lens14in the normal imaging mode, and places the second filter182that is a dummy lens on the optical axis of the lens14in the low-light imaging mode.

The setter36performs a setting process to set an amplification factor to be used by the image processor35in switching to the low-light imaging mode (in other words, when the external environment surrounding the imaging device10is dark) when the lens cover11is at the closed position to cover the opening15.

The recording controller37performs a recording process to record image data generated by the image processor35into the memory card48.

A link assembly43connects the lens cover11that opens or closes the opening15to an actuator44. The actuator44is connected to a drive circuit45. The drive circuit45is connected to the control unit31to drive the actuator44in response to a control signal (drive signal) from the control unit31. The actuator44with the above structure drives the lens cover11to serve as a drive for switching the lens cover11between the closed state (first state) in which subject light is restricted from entering the imaging element13and the open state (second state) in which subject light is allowed to enter the imaging element13.

Processing Performed by Control Unit31

The imaging device10generates image data and records the data into the memory card48with an imaging method described below. The imaging method includes a standby process performed when an imaging condition is unsatisfied (in other words, in the closed state) and the imaging process performed when the imaging device10in the closed state enters the open state in response to the imaging condition being satisfied. The imaging condition includes a wireless tag, such as an integrated circuit (IC), approaching a predetermined range. In this case, the control unit31determines whether a person carrying a wireless tag has entered a predetermined imaging area based on the intensity of a signal received with a radio communication module (not shown) connected to the control unit31. When the intensity of the received signal exceeds a predetermined threshold Xa, the control unit31determines that the person has entered the imaging area, or in other words, the imaging condition is satisfied.

The imaging condition may include, for example, receiving a recording signal transmitted from a mobile terminal such as a smartphone, receiving an infrared ray transmitted from a remote control, and detecting a voice with predetermined information with a microphone (not shown).

Standby Process

When the imaging condition is unsatisfied, the lens cover11is at the closed position. In this state, the imaging device10performs the standby process. When the imaging condition is satisfied, the lens cover11is at the open position, and the imaging device10performs the imaging process.

The standby process includes the setting process, the determination process, and an imaging preparation process. In the setting process, the setter36in the control unit31sets an amplification factor to be used by the image processor35to amplify the image signal to generate image data. In the determination process, the determiner32in the control unit31calculates a luminance value based on a luminance signal output from the illuminometer17, and determines that the external environment is bright in response to the value exceeding a predetermined threshold and determines that the external environment is dark in response to the value being less than or equal to the threshold. In the imaging preparation process, the imaging controller33or the filter controller34in the control unit31controls the components to allow imaging after the imaging condition is satisfied. The setting process, the determination process, and the imaging preparation process will be described below.

Setting Process

The setter36calculates a luminance value based on a luminance signal output from the illuminometer17and sets an amplification factor for the image signal based on the calculated luminance value. Typically, when the imaging device10captures an image, a smaller amount of light enters the imaging element13with its external environment being dark (in the low-light imaging mode) than with its external environment being bright (in the normal imaging mode). The setter36thus sets a higher amplification factor for the image processor based on the calculated luminance value as the external environment is darker (in other words, the luminance value is lower).

More specifically, amplification factors are prepared based on luminance values (brightness levels in the external environment) and are recorded in the recording medium38in, for example, a tabular format. The table includes the luminance values in the external environment divided into predetermined ranges, for which different amplification factors are recorded. For example, an amplification factor a is associated with a luminance value in the external environment being in a first range A. An amplification factor b lower than the amplification factor a is associated with a luminance value in the external environment being in a second range B indicating being brighter than in the first range A. An amplification factor c lower than the amplification factor b is associated with a luminance value in the external environment being in a third range C indicating being brighter than the second range B. An amplification factor d lower than the amplification factor c is associated with a luminance value in the external environment being in a fourth range D indicating being brighter than the third range C. An amplification factor e lower than the amplification factor d is associated with a luminance value in the external environment being in a fifth range E indicating being brighter than the fourth range D.

The setter36determines a range including the calculated luminance value among the first range A to the fifth range E by referring to the above table. The setter36then sets the amplification factor associated with the range as an amplification factor to be set for the image processor35. In other words, the setter36sets the value based on the calculated luminance value among values predetermined for brightness levels as the amplification factor.

The above table may include each value associated with the luminance value in the external environment as a correction value for the amplification factor instead of the amplification factor. In this case, for example, a luminance value calculated using the image signal output from the imaging element13with the lens cover11being at the closed position is 1 (in other words, a reference value), and the correction value for the amplification factor is set as the amount of correction to the reference value. The amount of correction may be the difference from the above reference value or the ratio to the reference value.

Determination Process

The determiner32calculates a luminance value based on a luminance signal output from the illuminometer17, and determines that the external environment is bright in response to the value exceeding the predetermined threshold and determines that the external environment is dark in response to the value being less than or equal to the threshold. The predetermined threshold is set based on the results of testing or simulations, and is prerecorded in the recording medium38.

Imaging Preparation Process

The imaging controller33controls the operation of each component in the imaging device10based on the determination result of the determination process. When the luminance value exceeds the threshold and the surrounding external environment is determined to be bright, the imaging controller33causes the imaging element13to output an image signal resulting from photoelectric conversion. The image processor35generates image data using the amplification factor set for the image signal in the setting process. Thus, the imaging element13receives power and continues to be driven when the lens cover11is at the closed position or in the first state. The generated image data is recorded into the memory card48. However, the lens cover11is at the closed position as described above. Thus, the image data to be generated does not include a subject outside the imaging device10.

When the luminance value is less than or equal to the threshold and the surrounding external environment is determined to be dark, the imaging controller33performs a process to allow imaging in the low-light imaging mode (described later). The filter controller34first controls the drive assembly184to move the first filter181off the optical axis of the lens14and place the second filter182on the optical axis of the lens14. The lens cover11thus moves to the open position to allow infrared light to enter the imaging element13. The imaging controller33then causes the illumination light sources161and162to emit infrared light as illumination light as described above. The imaging controller33causes the imaging element13to output an image signal resulting from photoelectric conversion. The image processor generates image data using the amplification factor set for the image signal in the setting process. The generated image data is recorded into the memory card48. However, the lens cover11is at the closed position as described above. Thus, the image data to be generated does not include a subject outside the imaging device10.

When the imaging condition is satisfied with the above standby process being performed, the imaging device10advances to the imaging process. The imaging process will now be described.

Imaging Process

When the imaging condition is satisfied, the imaging device10moves the lens cover11from the closed position to the open position for capturing an image of the subject. More specifically, the control unit31causes the drive circuit45to drive the actuator44to move the lens cover11to the open position with the link assembly43. The imaging element13receives subject light entering through the opening15and outputs an image signal to the image processor35. With the second filter182on the optical axis of the lens14in the low-light imaging mode, the imaging element13receives illumination light emitted from the illumination light sources161and162and reflected from the subject, and outputs an image signal.

The image processor35subjects the image signal output from the imaging element13to known image processes, such as an analog-to-digital (AD) conversion process, a signal amplification process, and a white balance process, and generates image data. In this state, the image processor35amplifies the image signal with the amplification factor set in the setting process during the above standby process. The recording controller37records the generated image data into the memory card48.

The control unit31may record the time when the lens cover11moves to the open position. The recording controller37may delete, based on the time, image data recorded during the imaging preparation process from the image data recorded in the memory card48.

Hereafter, the imaging controller33sets an amplification factor both in the normal imaging mode and in the low-light imaging mode based on image data to be generated. The image processor35generates image data using the set amplification factor. In other words, the amplification factor for the image signal is controlled with auto gain control (AGC). In this case, the imaging controller33performs one of first control or second control, or switches between the first control and the second control as appropriate to set the amplification factor. For the first control, the imaging controller33sets the amplification factor using correction data (correction table) generated by calculating amplification factors based on image data generated with the imaging device10being in the open state at a test site. The correction data includes multiple amplification factors calculated using image data generated with different brightness levels in the external environment at a test site and associated with the luminance of the image data. The correction data is recorded in the recording medium38. The imaging controller33reads, from the correction data, an amplification factor associated with the luminance of the image data generated by the imaging process and sets the factor as the amplification factor to be used. For the second control, the imaging controller33stores amplification factors calculated based on image data generated with the imaging device10being in the open state at an installation site and sets an amplification factor to be used. When performing the first control or the second control, the imaging controller33may set the amplification factor to be used using results obtained from, for example, artificial intelligence (AI) learning amplification factors calculated based on image data and stored.

When the imaging condition is no longer satisfied, the control unit31causes the drive circuit45to drive the actuator44to move the lens cover11to the closed position with the link assembly43. The filter controller34controls the drive assembly184to place the first filter181on the optical axis of the lens14. The imaging controller33causes the illumination light sources161and162to stop emitting illumination light. However, the control unit31causes the illuminometer17to continue its operation without stopping the operation. Thus, the illuminometer17operates when the lens cover11is at the closed position and the imaging device10is in the closed state, allowing the setter36in the control unit31to perform the setting process. When the imaging device10is in the closed state, the control unit31may supply power to the illuminometer17at predetermined intervals with, for example, pulse control (pulse-width modulation control, or PWM control).

The above standby process is performed to allow an amplification factor appropriate for imaging in the low-light imaging mode to be set in a shorter time than when the amplification factor is controlled and set with AGC after the imaging condition is satisfied. This reduces the delay before the imaging is started in the low-light imaging mode after the imaging condition is satisfied.

The process performed by the control unit31will be described with reference to the flowcharts inFIGS.5and6. The control unit31reads and executes a program recorded in the recording medium38to perform the processing in the flowchart.

In step S1, the setter36in the control unit31calculates a luminance value in the external environment based on a luminance signal output from the illuminometer17. The processing then advances to step S2. In step S2, the setter36reads the amplification factor recorded in the above table based on the calculated luminance value and sets the value as the amplification factor to be used by the image processor35in generating image data. The processing then advances to step S3. Steps S1and S2above correspond to the setting process.

In step S3, the determiner32in the control unit31determines whether the luminance value obtained in step S1exceeds the predetermined threshold (determination process). When the calculated luminance value is less than or equal to the threshold (in other words, the external environment is dark), the determiner32yields an affirmative determination result. The processing then advances to step S4. When the luminance value exceeds the threshold (in other words, the external environment is bright), the determiner32yields a negative determination result. The processing then advances to step S6(described later).

In step S4, the filter controller34in the control unit31controls the drive assembly184to move the first filter181off the optical axis of the lens14and place the second filter182on the optical axis of the lens14. The processing then advances to step S5. In step S5, the imaging controller33in the control unit31causes the illumination light sources161and162to emit infrared light as illumination light as described above. The processing then advances to step S6.

In step S6, the imaging controller33causes the imaging element13to output an image signal, and causes the image processor35to generate image data based on the output image signal. The recording controller37records the image data generated by the image processor35into the memory card48. The processing then advances to step S7. Steps S4to S6above correspond to the imaging preparation process.

In step S7, the control unit31determines whether the imaging condition is satisfied. When the intensity of the signal received with the radio communication module exceeds the threshold Xa as described above, the control unit31yields an affirmative determination result. The processing then advances to step S8. When the intensity of the received signal is less than or equal to the threshold Xa, the control unit31yields a negative determination result. The processing then returns to step S1.

In step S8, the control unit31causes the drive circuit45to drive the actuator44to move the lens cover11to the open position with the link assembly43. The processing then advances to step S9. In step S9, the imaging controller33causes the imaging element13to output an image signal, and causes the image processor35to generate image data based on the output image signal. The recording controller37records the image data generated by the image processor35into the memory card48. The processing then advances to step S10.

In step S10, the imaging controller33controls, with AGC, and calculates a new amplification factor based on the image data generated by the image processor35. The imaging controller33then sets the calculated new amplification factor to be used by the image processor35in generating image data. The processing then advances to step S11inFIG.6.

In step S11inFIG.6, the determination is performed as to whether the sensitivity of the imaging element13is appropriate. When the sensitivity of the imaging element13is appropriate, the control unit31yields an affirmative determination result. The processing then advances to step S12. When the sensitivity of the imaging element13is inappropriate, the control unit31yields a negative determination result. The processing then returns to step S10inFIG.5.

Steps S9to S11above correspond to the imaging process.

In step S12, the determination is performed as to whether the imaging condition is satisfied. When the intensity of the signal received with the radio communication module remains exceeding the threshold Xa, the control unit31yields an affirmative determination result. The processing then returns to step S9inFIG.5. When the intensity of the received signal is less than or equal to the threshold Xa, the control unit31yields a negative determination result. The processing then advances to step S13. In step S13, the control unit31causes the drive circuit45to drive the actuator44to move the lens cover11to the closed position with the link assembly43. When the imaging process is performed in the low-light imaging mode, the imaging controller33stops emitting illumination light from the illumination light sources161and162, and the filter controller34controls the drive assembly184to move the holder183and place the first filter181on the optical axis of the lens14. The processing then returns to step S1inFIG.5. In other words, the processing in steps S1and S2(operation of the illuminometer17) during the standby process is continued.

The structure according to the above embodiment produces the advantageous effects described below.

(1) The setter36in the control unit31sets an amplification factor to be used by the image processor35in generating image data based on the brightness level in the surrounding environment detected by the illuminometer17in the first state (closed state) in which the lens cover11restricts subject light from entering the imaging element13. This allows setting of an amplification factor appropriate for imaging to be performed after the imaging condition is satisfied with the lens cover11being at the closed position. This structure reduces the delay before image data is generated with an appropriate amplification factor after the lens cover11moves to the open position, as compared with when the amplification factor is controlled and set with AGC. The illuminometer17included in the imaging device10continues its operation with the lens cover11being at the closed position to allow the setter36to set the amplification factor to be used in generating image data based on the brightness level in the external environment with the lens cover11being at the closed position.

(2) The setter36sets a value predetermined for each brightness level in the surrounding environment as the amplification factor. The amplification factor to be used is set to the amplification factor recorded in, for example, a tabular format, and can be set in a shorter time than when the amplification factor is calculated every time based on output from the illuminometer17.

(3) The switch18places the second filter182on the front surface of the imaging element13when the brightness level in the surrounding environment of the imaging device10detected by the illuminometer17is less than or equal to the threshold in the first state (closed state) in which the lens cover11restricts subject light from entering the imaging element13. This structure reduces the delay before image data is generated with an appropriate amplification factor in the low-light imaging mode after the lens cover11moves to the open position, as compared with when the second filter182for transmitting infrared light as illumination light is placed on the front surface of the imaging element13and then imaging is started.

(4) The illumination light sources161and162emit illumination light when the brightness level in the surrounding environment of the imaging device10detected by the illuminometer17is less than or equal to the threshold in the first state (closed state) in which the lens cover11restricts subject light from entering the imaging element13. This structure reduces the delay before image data is generated with an appropriate amplification factor in the low-light imaging mode after the lens cover11moves to the open position, as compared with when illumination light is emitted and then imaging is started.

(5) After the lens cover11moves to the open position, the imaging controller33sets the amplification factor based on the image data generated by the image processor35in the second state (open state). The amplification factor set during the standby process can be adjusted based on an amplification factor calculated based on subject light actually entering the imaging element13, thus improving the image quality of image data to be generated.

Although various embodiments and modifications are described above, the present invention is not limited to the embodiments and the modifications. Other forms implementable within the scope of technical idea of the present invention fall within the scope of the present invention.

Although the imaging device10generates image data in the closed state in the above embodiment, the imaging device10may start generating image data after the imaging condition is satisfied. In other words, the imaging element13may not receive power and may stop driving until the imaging condition to start generating image data is satisfied.

FIGS.7and8are flowcharts in this case. The processing in steps S11to S14is the same as the processing in steps S1(calculation of a luminance value in the external environment) to S4(placement of the second filter on the optical axis) inFIG.5. When the result of determination is negative in step S13, the processing advances to step S24(described later).

In step S15subsequent to step S14, the control unit31determines whether the imaging condition is satisfied as in step S7inFIG.5. When the imaging condition is satisfied, the control unit31yields an affirmative determination result. The processing then advances to step S16. When the imaging condition is unsatisfied, the control unit31yields a negative determination result. The processing then returns to step S11.

In step S24after the negative determination result in step S13as well, the determination is performed as to whether the imaging condition is satisfied as in step S7inFIG.5. When the imaging condition is satisfied, the processing advances to step S17. When the imaging condition is unsatisfied, the processing returns to step S11.

In step S16, the illumination light sources161and162emit illumination light as in step S5inFIG.5. In subsequent step S17, the imaging controller33causes the imaging element13to start driving. As in step S6inFIG.5, the imaging controller33causes the imaging element13to output an image signal, and causes the image processor35to generate image data based on the output image signal. The recording controller37records the image data generated by the image processor35into the memory card48. The subsequent processing in each of steps S18to S22inFIG.8is the same as the corresponding processing in step S8inFIG.5(movement of the lens cover11to the open position) to step S12inFIG.6(determination as to whether the imaging condition is satisfied). In step S23after the negative determination result in step S22, the control unit31performs the same processing as in step S13inFIG.6. The imaging controller33causes the imaging element13to stop driving. The processing then returns to step S11inFIG.7.

This reduces the power consumption of the imaging device10until the imaging condition is satisfied.

The imaging device10may switch the processing to be performed between the above processing inFIGS.7and8and the above processing inFIGS.5and6in response to, for example, a setting operation performed by a user.