JP2002152991A - Imaging apparatus, photocapacitor device and charging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocapacitor for converting an optical energy to electrical energy, to realize automatic and efficient charging operation. SOLUTION: This photocapacitor device comprises a photoelectric converting part 122 for converting optical energy into electrical energy, a capacitor part 126 for storing the electrical energy, a photodetecting part 37 for detecting amount of optical signal in the optical beam, reflected from an object and a control part 60 for charging ht capacitor part 126 with the electrical energy converted by the photoelectric converting part 122, when an output of the photodetecting part 37 has exceeded the preset value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device, an optical storage device, and a charging method. In particular, the present invention relates to an imaging device, a light storage device, and a charging method for converting light into electric energy and storing the converted light.

[0002]

2. Description of the Related Art Conventionally, as one of means for storing electric energy in a power storage unit such as a secondary battery or a capacitor, light is converted into electric energy by using a photoelectric conversion element, and the obtained electric energy is used. A method of charging a power storage unit is known. This method is used in many portable devices because it can be charged using sunlight or the like even in places without a power supply facility such as outdoors. In addition, since this method is a clean energy supply means that does not generate harmful substances, it is also used for photovoltaic power storage devices of various sizes, such as household or industrial use.

[0003]

However, when, how much light, and how long the light such as the sun continuously strikes the photoelectric conversion element, it is usually an accidental event. For example, irradiation and non-irradiation of light on a photoelectric conversion element included in a portable device may be repeated.
In such a case, the charge and discharge of the power storage unit are repeated in a short cycle, and as a result, there is a problem that the power storage unit deteriorates.

[0004] Therefore, an object of the present invention is to provide an imaging device, a photovoltaic storage device, and a charging method that can solve the above-mentioned problems. This object is achieved by a combination of features described in the independent claims.
The dependent claims define further advantageous embodiments of the present invention.

[0005]

That is, according to a first embodiment of the present invention, a photoelectric conversion unit for converting light to electric energy, a power storage unit for storing electric energy, and a light amount of reflected light of a subject And a control unit that charges the electric storage unit with the electric energy converted by the photoelectric conversion unit when the output of the light detection unit exceeds a set value.

[0006] The control unit may cause the power storage unit to start charging when the output of the light detection unit exceeds the set value for a predetermined time. The control unit may cause the power storage unit to start charging on condition that the remaining capacity of the power storage unit is equal to or less than a predetermined lower limit. The control unit further includes a timer that outputs a time, provided that the time output by the timer is within a preset time zone.
Charging of the power storage unit may be started.

[0007] The light detecting section may be a photometric sensor that measures the amount of light in order for the imaging device to calculate the exposure. The light detection unit may be a light control sensor that measures strobe light reflected from the subject. The light control sensor may have a different sensitivity when outputting a signal to the control unit than during flash photography. The light detection unit may be an imaging device used for the imaging device to capture an image. The light detection unit may measure the light amount at a preset time interval. The light detection unit may measure the amount of light in a part of the image sensor.

According to another aspect of the present invention, a photoelectric conversion unit that converts light into electric energy, a light detection unit that detects a light amount near the photoelectric conversion unit, a power storage unit that can store electric energy, A control unit that charges the electric storage unit with the electric energy converted by the photoelectric conversion unit when an output of the light detection unit exceeds a set value.

According to another aspect of the present invention, there is provided a photoelectric conversion unit for converting light into electrical energy, and a power storage unit for storing electrical energy, wherein the electrical storage unit uses the electrical energy converted by the photoelectric conversion unit. In this method, the light amount is detected, and when the light amount exceeds a set value for a predetermined time, the electric energy converted by the photoelectric conversion unit is charged to the power storage unit.

The above summary of the present invention does not list all of the necessary features of the present invention, and a sub-combination of these features may also be an invention.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described through embodiments of the present invention. However, the following embodiments do not limit the claimed invention and have the features described in the embodiments. Not all combinations are essential to the solution of the invention.

(Embodiment) First, an imaging apparatus according to an embodiment of the present invention will be described. The imaging device according to the present embodiment is a digital camera 10.

FIG. 1 is a functional configuration diagram showing an outline of functions of a digital camera 10 according to the present embodiment. The digital camera 10 includes a photoelectric conversion unit 122 that converts light into electric energy, and a power storage unit 126 that is charged using the electric energy obtained by the photoelectric conversion unit 122.
In addition, the digital camera 10 includes a control unit 60 that controls charging of the power storage unit 126. Furthermore, the digital camera 10 includes a light detection unit 37 that detects light near the photoelectric conversion unit 122 and outputs the detection result to the control unit 60, and a timer 86 that outputs time to the control unit 60. .
The control unit 60 outputs the photoelectric conversion unit 12
2 is estimated. The control unit 60
Monitors the temporal change in the amount of light applied to the photoelectric conversion unit 122 by referring to the output of the timer 86. Then, when the output of the light detection unit 37 continuously exceeds a predetermined set value for a certain period of time or more, the control unit 60
It is determined that light strong enough to charge the photoelectric conversion unit 6 is stably irradiating the photoelectric conversion unit 122, and charging of the power storage unit 126 is started.

FIG. 2 is a detailed configuration diagram of the digital camera 10. The digital camera 10 mainly includes the imaging unit 2
0, an imaging control unit 40, a processing unit 60, a display unit 100, an operation unit 110, and a power supply unit 120.

The imaging unit 20 includes a mechanism member and an electric member related to photographing and image formation. Imaging unit 20
First, a photographing lens 22 for capturing and processing images,
An aperture 24, a shutter 26, an optical LPF (low-pass filter) 28, a CMOS 30, which is an example of a solid-state image sensor, an image signal processor 32, and a strobe 36 are included. The taking lens 22 includes a focus lens, a zoom lens, and the like. With this configuration, a subject image is formed on the light receiving surface of the CMOS 30. Depending on the light quantity of the formed subject image, the CMO
Electric charges are accumulated in each sensor element (not shown) in S30 (hereinafter, the electric charges are referred to as “accumulated charges”). The stored charges are sequentially read out as voltage signals by the shift register.

Since the digital camera 10 generally has an electronic shutter function, a mechanical shutter such as the shutter 26 is not essential. In order to realize the electronic shutter function, the CMOS 30 is provided with a shutter drain via a shutter gate. When the shutter gate is driven, accumulated charges are swept out to the shutter drain. By controlling the shutter gate, the time for accumulating the electric charges in each sensor element, that is, the shutter speed can be controlled.

The voltage signal output from the CMOS 30, ie, the analog signal, is converted into R, G, B
The components are separated into colors, and the white balance is adjusted first. Subsequently, the imaging signal processing unit 32 performs gamma correction,
The R, G, and B signals are sequentially A / D converted at necessary timing, and the resulting digital image data (hereinafter, simply referred to as “digital image data”) is output to the processing unit 60.

The image pickup unit 20 has a finder 34 and a strobe 36. L not shown in the viewfinder 34
A CD may be installed, in which case, a main CPU described later is used.
Various information from 62 and the like can be displayed in the finder 34. The strobe 36 functions by emitting light when electric energy stored in a capacitor (not shown) is supplied to the discharge tube 36a. The light control sensor 37 measures the amount of reflected light of the subject, and more specifically, measures strobe light reflected from the subject, and outputs the light to the main CPU 62 with the light control sensor 37. The main CPU 62 sets an appropriate amount of strobe light based on the amount of reflected light of the subject. In the present embodiment, the light control sensor 37 is used as the light detection unit 37 described above. Further, the amplifier 38 may amplify the light detection signal output from the dimming sensor 37 and output the amplified signal to the main CPU 62.

The imaging control unit 40 includes a lens driving unit 4
2. It has a focus drive unit 44, an aperture drive unit 46, a shutter drive unit 48, an imaging system CPU 50 that controls them, a distance measurement sensor 52, and a photometry sensor 54. The driving units such as the lens driving unit 42 each have a driving unit such as a stepping motor. When a release switch 114 described later is pressed, the distance measurement sensor 52 measures the distance to the subject, and the photometry sensor 54 measures the brightness of the subject. The measured distance data (hereinafter simply referred to as “distance measurement data”) and the subject luminance data (hereinafter simply referred to as “photometry data”) are sent to the imaging system CPU 50. Imaging system CPU 50
Controls the lens drive unit 42 and the focus drive unit 44 to adjust the zoom magnification and focus of the photographing lens 22 based on the photographing information such as the zoom magnification designated by the user. Further, the imaging system CPU 50 is configured to capture an image,
The position of the taking lens 22 is moved by controlling the lens driving unit 42. Further, the imaging system CPU 50 determines the exposure based on the photometric data.

The imaging system CPU 50 may determine the aperture value and the shutter speed based on the integrated value of the RGB digital signals of one image frame, that is, AE information. According to the determined value, the aperture driving unit 46 and the shutter driving unit 48 adjust the aperture amount and
6 is opened and closed.

When the user instructs to capture an image, C
The MOS 30 starts charge accumulation, and after the shutter time calculated from the photometric data has elapsed, the accumulated charge is output to the image signal processing unit 32.

The processing unit 60 is a unit that implements the control unit 60 described with reference to FIG. Processing unit 60
Is the entire digital camera 10, especially the processing unit 60
A main CPU 62 for controlling itself, a memory control unit 64 controlled by the main CPU 62, a YC processing unit 70, an optional device control unit 74, a compression / decompression processing unit 78, a communication I / F unit 8
0, a charge switch 124 is provided. Main CPU 62
Exchanges necessary information with the imaging system CPU 50 through serial communication or the like. The operation clock of the main CPU 62 is provided from a clock generator 88. The clock generator 88 includes the imaging system CPU 50 and the display unit 1
00 are provided with clocks of different frequencies. The charging switch 124 is a switch interposed between the photoelectric conversion unit 122 and the power storage unit 126. The charge switch 124 performs switching of the circuit according to a control signal from the main CPU 62, thereby achieving switching between charging and non-charging of the power storage unit 126.

The main CPU 62 is provided with a character generator 84 and a timer 86. The timer 86 is backed up by a battery and always counts the date and time.
From this count value, information about the shooting date and time and other time information are given to the main CPU 62. The character generation unit 84 generates character information such as a shooting date and time and a title, and the character information is appropriately combined with the captured image.

The memory control unit 64 includes a nonvolatile memory 66
And the main memory 68. Non-volatile memory 66
Is composed of an EEPROM (electrically erasable and programmable ROM), a flash memory, and the like, and stores data to be retained even when the power of the digital camera 10 is off, such as setting information by a user and adjustment values at the time of shipment. ing. The non-volatile memory 66 may have a main CP
A boot program or a system program of U62 may be stored. On the other hand, the main memory 68 generally has a D
It is composed of a relatively inexpensive and large-capacity memory such as a RAM. The main memory 68 has a function as a frame memory for storing data output from the imaging unit 20, a function as a system memory for loading various programs, and a function as a work area. The non-volatile memory 66 and the main memory 68
Data is exchanged with each unit inside and outside the unit 0 via the main bus 82.

The YC processing section 70 performs YC conversion on the digital image data, and outputs a luminance signal Y and a color difference (chroma) signal B-
Generate Y, RY. The luminance signal and the color difference signal are temporarily stored in the main memory 68 by the memory control unit 64.
The compression / decompression processing unit 78 sequentially reads out the luminance signal and the color difference signal from the main memory 68 and compresses them. The data thus compressed (hereinafter simply referred to as “compressed data”) is written to a memory card, which is a type of the optional device 76, via the optional device control section 74.

The processing unit 60 further includes an encoder 72
With. The encoder 72 receives a luminance signal and a color difference signal, converts them into a video signal (NTSC or PAL signal), and outputs the video signal from a video output terminal 90. When a video signal is generated from data recorded in the optional device 76, the data is first supplied to the compression / decompression processing unit 78 via the optional device control unit 74. Subsequently, the data subjected to the necessary expansion processing by the compression / expansion processing unit 78 is converted into a video signal by the encoder 72.

The optional device control section 74 generates a necessary signal between the main bus 82 and the optional device 76, performs logical conversion, or converts voltage according to the signal specifications recognized by the optional device 76 and the bus specifications of the main bus 82. And so on. The digital camera 10 may include, for example, a PCM as an optional device 76 in addition to the above-described memory card.
A standard CIA-compliant standard I / O card may be supported. In that case, the optional device control unit 74
It may be constituted by an IA bus control LSI or the like.

The communication I / F unit 80 is provided for the digital camera 10
Communication specifications supported by, for example, USB, RS-23
2C, Ethernet (registered trademark), Bluetooth
h, IrDA, etc., according to specifications such as protocol conversion. The communication I / F unit 80 includes a driver IC as required, and connects to an external device including a network and a connector 9.
Communicate via 2 In addition to these standard specifications,
For example, data may be exchanged with an external device such as a printer, a karaoke machine, and a game machine by a unique I / F.

The display unit 100 includes an LCD monitor 10
2 and an LCD panel 104. These are the LCD driver monitor driver 106, panel driver 10
8 respectively. LCD monitor 102
Is provided on the back of the camera with a size of, for example, about 2 inches, and displays a current shooting and playback mode, a zoom ratio for shooting and playback, a remaining battery level, a date and time, a screen for mode setting, a subject image, and the like. . The LCD panel 104 is, for example, a small black-and-white LCD provided on the upper surface of the camera and has
/ NORMAL / BASIC etc.), information such as strobe light emission / non-light emission, standard number of recordable images, number of pixels, battery capacity, etc. are simply displayed.

The operation unit 110 includes mechanisms and electrical members necessary for the user to set or instruct the operation and the mode of the digital camera 10. The power switch 112 determines whether the power of the digital camera 10 is turned on or off. The release switch 114 has a two-stage pressing structure of half pressing and full pressing. As an example, AF and AE are locked by a half-press, captured images are captured by a full-press, and are recorded in the main memory 68, the optional device 76, etc. after necessary signal processing, data compression, and the like. The operation unit 110 may receive a setting using a rotary mode dial, a cross key, or the like in addition to these switches, and these are collectively referred to as a function setting unit 116 in FIG. Examples of operations or functions that can be specified by the operation unit 110 include “file format”, “special effects”, “printing”, “determine / save”, and “display switching”. The zoom switch 118 determines a zoom magnification.

The power supply unit 120 includes a photoelectric conversion unit 122
And a power storage unit 126. In the present embodiment, a solar cell is used as the photoelectric conversion unit 122. In the present embodiment, the photoelectric conversion unit 122 is disposed near the light detection unit 37. Here, being disposed in the vicinity means that the photoelectric conversion unit 12
2 and the light detection unit 37 are respectively arranged at least on the same casing. In the case of the present embodiment, the photoelectric conversion unit 122 and the light detection unit 37 are preferably arranged on adjacent surfaces of the housing of the digital camera 10, for example, on the front surface and the top surface, respectively. More preferably, the photoelectric conversion unit 122 and the light detection unit 37 are arranged together on the same surface of the housing of the digital camera 10, for example, the front surface or the top surface. It should be noted that the front surface refers to a surface facing the subject side during shooting.

On the other hand, in the present embodiment, a nickel-cadmium storage battery is used as the power storage unit 126. The power storage unit 126 is connected to the main CPU 62 so as to detect the remaining amount of power that can be released (hereinafter, referred to as “remaining capacity”. The power storage unit 126 may be a nickel-metal hydride storage battery or a lithium ion storage battery. The power storage unit 12 may be used.
As 6, a capacitor or the like may be used.

The main operation of the above configuration is as follows. First, the power switch 11 of the digital camera 10
2 is turned on, and power is supplied to each part of the camera. The main CPU 62 determines whether the digital camera 10 is in the shooting mode or the playback mode by reading the state of the function setting unit 116.

When the camera is in the shooting mode, the main C
The PU 62 monitors the half-pressed state of the release switch 114. When the half-pressed state is detected, the main CPU 62
Obtains photometry data and distance measurement data from the photometry sensor 54 and the distance measurement sensor 52, respectively. The imaging control unit 40 operates based on the obtained data, and the focus, aperture, and the like of the photographing lens 22 are adjusted. Once the adjustment is complete,
Characters such as "standby" are displayed on the LCD monitor 102 to inform the user of the fact, and then the state of the release switch 114 being fully pressed is monitored. Release switch 1
When the shutter 14 is fully pressed, the shutter 26 is closed after a predetermined shutter time, and the accumulated charges in the CMOS 30 are discharged to the image signal processing unit 32. The digital image data generated as a result of the processing by the imaging signal processing unit 32 is output to the main bus 82. The digital image data is temporarily stored in the main memory 68, and then processed by the YC processing unit 70 and the compression / decompression processing unit 78.
4 to the optional device 76. The recorded image is displayed on the LCD monitor 102 for a while in a frozen state, so that the user can know the captured image. Thus, a series of photographing operations is completed.

When the digital camera 10 is in the playback mode,
The main CPU 62 reads the last captured image from the main memory 68 via the memory control unit 64 and displays this on the LCD monitor 102 of the display unit 100.
When the user instructs “forward” or “reverse” in the function setting section 116 in this state, images taken before and after the currently displayed image are read out, and the LCD monitor 1
02 is displayed.

On the other hand, when the power switch 112 is turned off, the power storage process by the power supply unit 120 is started.

FIG. 3 is a flowchart of the charging process in the digital camera 10. When the user turns off the power switch 112, the power storage process starts (S10).
0). That is, control unit 60 acquires the remaining capacity of power storage unit 126 (S102), and determines whether the remaining capacity is equal to or less than a predetermined lower limit (S104). Here, the predetermined lower limit value is a remaining capacity after the power storage unit 126 has sufficiently discharged so that a memory effect does not occur even if recharging is performed. The control unit 60 performs S102 and S10
Step 4 is repeated until the obtained remaining capacity of the power storage unit 126 becomes equal to or less than the lower limit. When the obtained remaining capacity becomes equal to or less than the lower limit, the process proceeds to S106.

In S106, the control unit 60 obtains the current time from the timer 86. Next, the control unit 60 determines whether or not the obtained time is within a preset time zone (S108). The preset time zone refers to, for example, a time zone in which the power storage unit 126 can be charged to a predetermined capacity by sunset when charging is started using sunlight. The predetermined capacity may be the maximum capacity of the power storage unit 126, or may be a capacity corresponding to the power required to perform one or more normal shootings using the digital camera 10. Alternatively, the capacity may be a capacity corresponding to the power required to perform one or more flash photography using the digital camera 10. In addition, the preset time zone is a time zone in which charging can be continuously performed during the daytime when sunlight is started to be charged during the daytime, for example, including 0:00 pm. There may be. The preset time zone is set at least from the time after the sunrise time of the day to the sunset time of the day. By setting the time zone in this manner, it is possible to prevent the charging from being started due to the temporary irradiation of the light detection unit 37 with artificial light at night.

The control unit 60 continues the processing of S106 and S108 until the acquired current time is included in the preset time zone, and when the acquired current time is included in the preset time zone, Shifts to the process of S112.

In S112, the controller 60 changes the sensitivity of the light control sensor 37. In the present embodiment, the dimming sensor 37 is used as the light detection unit 37 described with reference to FIG. 1, that is, for estimating the intensity of light irradiating the photoelectric conversion unit 122. This is for adjusting the sensitivity of the light control sensor 37 to the value obtained. The control unit 60
For example, the sensitivity of the light control sensor 37 is changed by changing the amplification factor of the amplifier 38.

Next, in S114, the control unit 60
The input of the detected light amount is received from the light detection unit 37. The control unit 60 determines that the input light amount exceeds the set value (S11).
6) If the state continues for a preset time or longer (S118), it is determined that light having sufficient intensity to charge the power storage unit 126 is stably radiated to the photoelectric conversion unit 122. Then, charging switch 124 is controlled to start charging power storage unit 126 (S120).

As described above, according to the imaging device of the present embodiment, charging is automatically started at the timing when light required for photoelectric conversion is emitted simply by leaving the imaging device unattended. In addition, it is possible to charge a sufficient amount for photographing, and it is possible to reduce scenes in which photographing cannot be performed due to insufficient charging. Further, in the present embodiment, since electricity is stored after sufficiently discharging, there is an effect that the memory effect is hard to appear even when a secondary battery having a memory effect is used.

Although the present invention has been described with reference to the embodiment, the technical scope of the present invention is not limited to the scope described in the above embodiment. Various changes or improvements can be added to the above embodiment. It should be noted that such modified or improved embodiments may be included in the technical scope of the present invention.
It is clear from the description of the claims.

For example, in the above embodiment, the light control sensor 37 is used as the light detection unit 37, but the light detection unit 37 uses the photometry sensor 54 that measures the amount of light in order to calculate the exposure by the imaging device. Is also good. Also, the light detection unit 37
May have a filter that selectively transmits light with high photoelectric conversion efficiency when the photoelectric conversion unit 122 converts the electric energy into electric energy. By providing a filter, it is possible to more accurately detect the amount of light having a wavelength with high photoelectric conversion efficiency,
The sensitivity of the light quantity measurement can be adjusted.

Further, as the light detecting section 37, an image pickup device by which the digital camera 10 picks up an image may be used. In this case, the imaging device may be a CCD,
An XY address type image sensor such as a MOS may be used.

When an image pickup device is used as the light detecting section 37, it is preferable that the measurement of the light amount is performed at predetermined time intervals. This is because the power consumption of the image sensor is suppressed by operating the image sensor intermittently. Further, the light detection unit 37
Is an XY address type image sensor, the charge accumulated in some pixels of the image sensor may be read.
As described above, it is more preferable to measure the light amount in a part of the image sensor because the power consumption becomes smaller than when the light amount is detected in the entire image sensor.

FIG. 4 shows a CMOS 30 as the light detecting section 37.
5 is a flowchart of a charging process performed by the digital camera 10 when using the camera. The charging process shown in this figure is different from the process shown in FIG. 3 in that the light amount is measured in a part of the CMOS 30 at regular time intervals. S200 to S208 in FIG. 4, and S216, S21
8 and S220 correspond to S100 to S1 described in FIG.
08 and the same as S116, S118, and S120, and a description thereof will be omitted. In S210, the control unit 60 determines whether a predetermined time has elapsed since the previous photometry. If a predetermined time has elapsed since the previous photometry, the control unit 60 proceeds to the process of S214, and if the predetermined time has not elapsed, the control unit 60 continues monitoring the elapsed time from the previous photometry. In step S214, the amount of light is measured by reading out the accumulated charge in some pixels of the CMOS 30, and the control unit 60
And outputs the measured light quantity.

[0048]

As is apparent from the above description, according to the present invention, light can be converted into electric energy and charged while suppressing deterioration of the power storage unit.

[Brief description of the drawings]

FIG. 1 is a functional configuration diagram illustrating an outline of functions of a digital camera 10 according to an embodiment.

FIG. 2 is a detailed configuration diagram of the digital camera 10.

FIG. 3 is a flowchart of a charging process in the digital camera 10.

FIG. 4 is a flowchart of a charging process performed by the digital camera 10 when the CMOS 30 is used as the light detection unit 37.

[Explanation of symbols]

 Reference Signs List 30 CMOS 37 Light detection unit 38 Amplifier 54 Photometry sensor 60 Control unit 62 Main CPU 86 Timer 112 Power switch 122 Photoelectric conversion unit 124 Charge switch 126 Power storage unit

Claims (12)

[Claims] A photoelectric conversion unit configured to convert light into electric energy; a power storage unit configured to store the electric energy; a light detection unit configured to detect an amount of reflected light of a subject; and an output of the light detection unit. An imaging device comprising: a control unit that charges the electric storage unit with the electric energy converted by the photoelectric conversion unit when the set value is exceeded. 2. The control section, when an output of the light detection section exceeds the set value for a time exceeding a preset time,
The imaging device according to claim 1, wherein the power storage unit starts charging. 3. The control unit causes the power storage unit to start charging on condition that the remaining capacity of the power storage unit is equal to or less than a predetermined lower limit. An imaging device according to claim 1. 4. The apparatus further comprises a timer for outputting a time, wherein the control unit causes the power storage unit to start charging on condition that the time output by the timer is within a preset time zone. The imaging device according to claim 1, wherein: 5. The imaging device according to claim 1, wherein the light detection unit is a photometric sensor that measures a light amount in order to calculate an exposure of the imaging device. 6. The imaging device according to claim 1, wherein the light detection unit is a light control sensor that measures strobe light reflected from the subject. 7. The photographing apparatus according to claim 6, wherein the light control sensor has a different sensitivity when outputting a signal to the control unit than in flash photographing. 8. The imaging device according to claim 1, wherein the light detection unit is an imaging element used by the imaging device to capture an image. 9. The imaging device according to claim 1, wherein the light detection unit measures the amount of light at a predetermined time interval. 10. The imaging apparatus according to claim 8, wherein the light detection unit measures a light amount in a part of the imaging device. 11. A photoelectric conversion unit that converts light into electric energy, a light detection unit that detects a light amount near the photoelectric conversion unit, a power storage unit that can store the electric energy, A control unit that charges the electric storage unit with the electric energy converted by the photoelectric conversion unit when an output exceeds a set value. 12. A charging device, comprising: a photoelectric conversion unit that converts light into electric energy; and a power storage unit that can store the electric energy, wherein the charging unit charges the power storage unit using the electric energy converted by the photoelectric conversion unit. A method comprising: detecting a light amount, and when the light amount exceeds a set value for a predetermined time, charging the electric storage unit with the electric energy converted by the photoelectric conversion unit. How to charge.