Imaging device, control method thereof, program, and storage medium

Abstract

To provide an imaging device that makes it possible to use a power storage device having a rated voltage lower than that of a main power supply as a backup power supply for the main power supply.SOLUTION: An imaging device includes a load circuit, a power supply unit that supplies power to the load circuit, a power storage device unit that supplies power to the load circuit, a first control unit that performs emergency shutdown processing of the imaging device when power from the power supply unit is suddenly cut off, a first power supply path that supplies power from the power storage device unit to the load circuit, a second power supply path that supplies power from the power storage device unit to the first control unit, and a second control unit that controls the power supply path such that when the power from the power supply unit is suddenly cut off, the second power supply path is enabled and power for performing the emergency shutdown processing is supplied from the power storage device unit to the first control unit.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to an imaging apparatus equipped with an electricity storage device. [Background technology]

[0002] Electric storage devices such as electric double layer capacitors are used to supplement the main power supply source of electronic devices. Because electric storage devices such as electric double layer capacitors have a larger capacity than ordinary capacitors, they can supply peak currents that drive loads, thereby reducing the load on the main power supply source.

[0003] For example, in an imaging device, when driving a load with a large peak current, such as an image sensor capable of high-speed readout of pixel data, the load on the main power supply source, such as a battery, can be reduced by peak current assistance provided by a power storage device.

[0004] Furthermore, when the main power supply source is interrupted, the energy stored in the power storage device can be used to perform system shutdown processing and backup processing. For example, in an imaging device, when the main power supply source such as a battery is interrupted, the power storage device can be used to save setting values ​​and shooting data, and to perform power shutdown processing, etc.

[0005] However, since power storage devices are large in size, incorporating multiple power storage devices would hinder efforts to miniaturize electronic devices, so it is desirable to achieve multiple functions using a single power storage device.

[0006] For example, Patent Document 1 proposes a system that changes the connection destination depending on the voltage of the power storage device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-166797 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the conventional technology disclosed in the above-mentioned Patent Document 1 does not allow a power storage device to be connected to a load that requires a power supply voltage higher than the rated voltage of the power storage device. For example, in an imaging device, if a power storage device with a rated voltage lower than that of a main power supply source such as a battery is connected to an imaging sensor that can operate on a power supply voltage lower than that of the main power supply source, the connection destination of this power storage device cannot be switched to the main power supply. In other words, a power storage device for peak current assist such as an imaging sensor cannot also be used as a backup power source for the main power supply source.

[0009] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide an imaging device that makes it possible to use an energy storage device with a lower rated voltage than a main power supply as a backup power supply for the main power supply. [Means for solving the problem]

[0010] The imaging device according to the present invention is characterized in that it comprises a load circuit, a power supply unit that supplies power to the load circuit, a power storage device unit that supplies power to the load circuit, a first control unit that performs emergency shutdown processing of the imaging device when power from the power supply unit is suddenly cut off, a first power supply path that supplies power from the power storage device unit to the load circuit, a second power supply path that supplies power from the power storage device unit to the first control unit, and a second control unit that controls the power supply path so that when power from the power supply unit is suddenly cut off, the second power supply path is enabled and power for performing the emergency shutdown processing is supplied from the power storage device unit to the first control unit. [Effects of the Invention]

[0011] According to the present invention, it is possible to use an electricity storage device having a lower rated voltage than a main power supply as a backup power supply for the main power supply. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the configuration of an imaging apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a block diagram showing the configuration of an imaging power supply unit. [Figure 3] FIG. 1 is a diagram showing the structure of an imaging device. [Figure 4] FIG. 2 is a diagram showing a more detailed block configuration of an imaging power supply unit. [Figure 5A] 4 is a flowchart showing the operation of the imaging power supply unit. [Figure 5B] 4 is a flowchart showing the operation of the imaging power supply unit. [Figure 5C] 4 is a flowchart showing the operation of the imaging power supply unit. [Figure 6] FIG. 4 is a diagram showing characteristics of the power storage device unit. [Figure 7] FIG. 10 is a diagram illustrating the determination of the deterioration degree. [Figure 8] FIG. 4 is a diagram showing settings of a main power supply path switching unit and a power storage device charge / discharge unit. [Figure 9] 4 is a timing chart showing state transitions of the imaging device. [Figure 10] FIG. 10 is a diagram showing a notification screen for a user. [Figure 11] A diagram showing the backup power supply configuration for the CPU power supply. [Figure 12] 5 is a timing chart showing state transitions of the imaging device when an emergency power-off occurs. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0014] The configuration of an imaging device 100 according to one embodiment of the present invention will be described below with reference to FIG.

[0015] 1, an imaging drive control unit 1012 receives commands from a control unit 1011 in a CPU 101 that controls the entire imaging device 100, and controls an imaging sensor 102 such as a CMOS sensor based on the commands. The imaging sensor 102 controlled in this manner performs photoelectric conversion (exposure) by capturing light from a subject into each pixel, and the resulting signal is converted (read out) into digital data by an A / D converter in the imaging sensor 102.

[0016] Image data generated based on the digital data obtained from each pixel is loaded into temporary memory 1014 within CPU 101. When in a shooting standby state in which a live view image is to be displayed, data loaded from image sensor 102 is expanded into temporary memory 1014 in response to a thinning-out drive command for live view images from control unit 1011. The acquired image is corrected by image correction unit 1015, and then converted into display data by display image conversion unit 1016, and displayed on display unit 103 as a live view image.

[0017] When a user operates a release button on an operation unit (not shown) to issue an instruction to take a photograph, image data for recording is output from the image sensor 102, which is driven and controlled to take a still image for recording, in accordance with an instruction from the image capture drive control unit 1012. The image data expanded in the temporary memory 1014 is corrected by the image correction unit 1015, and is compressed using JPEG or the like by the image compression unit 1013 before being recorded in the recording unit 104 as a still image.

[0018] When a user operates a video recording button on an operation unit (not shown) to issue an instruction to shoot a video, multiple frames of image data are continuously output as a video from the image sensor 102, which is driven and controlled to shoot a video for recording in accordance with an instruction from the image capture drive control unit 1012. The image data for each frame of the video expanded in the temporary memory 1014 is corrected by the image correction unit 1015, and then compressed for video by the image compression unit 1013 before being recorded as a video in the recording unit 104. Furthermore, when the user issues an instruction to stop shooting the video, the series of video shooting and recording processes are stopped and the device enters a shooting standby state. Although not shown in FIG. 1, the image capture device 100 also includes an operation unit for inputting user operations.

[0019] Representative operating modes of the imaging device 100 include a still image mode and a video mode. More specifically, the still image mode includes a single-shot mode, in which one still image is captured each time the release button is pressed, and a continuous-shot mode (continuous-shot shooting mode), in which still images are captured continuously while the release button is pressed. The continuous-shot mode is further divided into a high-speed continuous-shot mode, in which a greater number of images are captured per unit time, and a low-speed continuous-shot mode, in which a relatively smaller number of images are captured per unit time.

[0020] In addition to the single-shot and continuous-shot modes, there is also a high-speed readout mode that simultaneously reads out a larger number of pixels from the image sensor 102 to obtain a still image with reduced distortion of a moving subject, and a low-speed readout mode that simultaneously reads out a smaller number of pixels. Among the high-speed readout modes, there is also a global shutter mode that simultaneously reads out all pixels.

[0021] Within the video mode, the operation modes of the imaging device 100 are classified according to the screen size of the video to be recorded, and include 8K recording mode, 4K recording mode, FHD recording mode, etc. In the video mode, the frame rate can also be changed, and the operation modes of the imaging device 100 are also classified according to this. The operation mode of the imaging device 100 may be changed in response to a user operation, or may be automatically changed by the control unit to the operation mode that is optimal for the user.

[0022] The power supply unit 107 converts power supplied from the battery 108 or the USB power supply unit 110 into the required voltage and current and supplies it to each block. The battery 108 corresponds to the power supply source for the image capture device 100 and is, for example, a removable lithium-ion battery. The USB power supply unit 110 is an external power supply unit that supplies power from an external power supply device to the image capture device.

[0023] The battery monitoring unit 109 monitors the voltage and discharge current of the battery 108 and transmits the information to the control unit 1011. The battery monitoring unit 109 can also calculate the internal resistance of the battery 108 from the discharge current and voltage drop of the battery 108.

[0024] Based on the battery information provided by the battery monitoring unit 109, when the remaining capacity of the battery 108 is low or the internal resistance is increasing, the control unit 1011 changes the control, for example, by putting the imaging device 100 into a low power consumption state.

[0025] The imaging device 100 can also operate using power supplied from a USB power supply unit 110 instead of the battery 108. The USB power supply unit 110 is, for example, a mobile battery or an AC adapter equipped with a USB cable. The power supply unit 107 has a USB connector. When the USB power supply unit 110 is connected to this USB connector, power from the USB power supply unit 110 is supplied to the power supply unit 107. In FIG. 1, the power supply unit 107 only includes a CPU power supply unit 1071 that supplies power to the CPU 101 and an imaging power supply unit 1072 that supplies power to the imaging sensor 102, which is a load circuit for the power supply, but the power supply unit 107 also includes power supplies that supply power to the display unit 103, the recording unit 104, and other blocks.

[0026] As will be described in more detail with reference to Figure 11, the CPU power supply unit 1071 also has the function of temporarily supplying power to the power supply control unit 106 in the event of an emergency main power interruption, such as when the user accidentally removes the battery 108 or USB power supply unit 110 from the imaging device 100.

[0027] The power supply control unit 106 controls the power supply unit 107 based on instructions from the control unit 1011. For example, the power supply control unit 106 controls the on / off of each power supply in the power supply unit 107, changes the output voltage, etc. Although FIG. 1 illustrates a case where the power supply control unit 106 is a device separate from the CPU 101, the power supply control unit 106 may be configured within the CPU 101. Alternatively, the control unit 1011 may be configured to directly control the power supply unit 107.

[0028] The temperature sensor (temperature detection means) 105 is disposed within the image capture device 100 and acquires temperature data in the vicinity of the temperature sensor 105. The control unit 1011 can estimate the temperature of any location in the image capture device 100 based on the output data of the temperature sensor 105. The number of temperature sensors 105 is not limited to one, and the control unit 1011 can also estimate the temperature of the image capture device 100 in more detail based on the output data of two or more temperature sensors 105.

[0029] The control unit 1011 can change the control of the imaging device 100 in accordance with the temperature information. For example, if the estimated temperature of the imaging sensor 102 exceeds a predetermined temperature, the control unit 1011 sends a command to the imaging drive control unit 1012 to stop the imaging operation. At the same time, the control unit 1011 sends a command to the power control unit 106 to turn off the imaging power supply unit 1072. This makes it possible to safely stop the imaging operation when the temperature of the imaging sensor 102 falls outside the usable range.

[0030] 2 is a block diagram showing the configuration of essential parts, including the imaging power supply unit 1072, in this embodiment. Power supplied from the battery 108 or the USB power supply unit 110 is input to an imaging main power supply unit 201 and a power storage device charge / discharge unit 204. The imaging main power supply unit 201 converts the voltage of the battery 108 into an operating voltage for the imaging sensor 102 and outputs it. The imaging main power supply unit 201 includes a transformer circuit, such as a DC / DC converter or an LDO (Low Drop Out) regulator.

[0031] The power storage device charging / discharging unit 204 charges the power storage device unit 202 using power from the battery 108 or the USB power supply unit 110. The power storage device unit 202 is, for example, an electric double layer capacitor (EDLC). Alternatively, a power storage device such as an all-solid-state battery may be used as long as it has a large capacity sufficient to provide the driving power for the image sensor 102 and a low equivalent series resistance (ESR) sufficient to accommodate the response speed of the image sensor 102. The power supply selection unit 203 selects at least one of the image capture main power supply unit 201 and the power storage device unit 202 to supply power to the image sensor 102.

[0032] The power supply source selection unit 203 is controlled by the power supply control unit 106 so that power from the battery 108 or the USB power supply unit 110 via the imaging main power supply unit 201 is supplied to the image sensor 102. However, if the power consumed by the image sensor 102 is entirely supplied by the power from the battery 108 or the USB power supply unit 110, there is a risk that the power consumption will exceed the allowable power of the battery 108 or the USB power supply unit 110. For example, when the operating mode of the imaging device 100 is global shutter mode, the image sensor 102 consumes a large amount of power instantaneously to simultaneously read out all pixels. At this time, there is a risk that the allowable output current of the battery 108 or the USB power supply unit 110 will be exceeded. For this reason, in operating modes of the imaging device that require a large maximum power consumption, such as global shutter mode, the power supply source selection unit 203 is controlled so that power from the power storage device unit 202 is supplied to the image sensor 102. In addition to the global shutter mode, other operating modes with high power consumption that may exceed the allowable current include modes in which multiple pixels are read out simultaneously and modes in which the readout speed is increased for the purpose of high-speed continuous shooting.

[0033] When the imaging sensor 102 consumes the power stored in the power storage device unit 202, no instantaneous large current is drawn from the battery 108 or the USB power supply unit 110. Note that although the description has been given in which the power supply source selection unit 203 supplies the output of either the imaging main power supply unit 201 or the power storage device unit 202 to the imaging sensor 102, it is not necessarily required to select just one, and power may be supplied to the imaging sensor 102 from both.

[0034] Here, when the power storage device charging / discharging unit 204 performs constant current charging on the power storage device unit 202, the output current of the power storage device charging / discharging unit 204 is kept constant, and the output voltage is made variable in accordance with the rise in voltage of the power storage device unit 202. When the voltage of the power storage device unit 202 reaches a charging completion voltage, the charging operation is stopped.

[0035] At this time, the output voltage and output current of the power storage device charging / discharging unit 204, as well as the charge completion voltage, can be changed by the power supply control unit 106. For example, by setting the output current of the power storage device charging / discharging unit 204 to a large value, it is possible to shorten the time until the power storage device unit 202 is fully charged. On the other hand, if the output current is set to a large value, the power drawn from the battery 108 or the USB power supply unit 110 increases. Therefore, in order to reduce the power drawn from the battery 108 or the USB power supply unit 110, the output current value of the power storage device charging / discharging unit 204 can be set to a small value.

[0036] Furthermore, by setting the charge completion voltage of the power storage device charge / discharge unit 204 high, more power can be supplied from the power storage device unit 202 to the image sensor 102. However, if the charge completion voltage is set high, there is a concern that a high voltage will be applied to the power storage device unit 202 for a long period of time, which may accelerate deterioration of the power storage device unit 202. Therefore, in order to prevent deterioration, the charge completion voltage of the power storage device charge / discharge unit 204 can also be set low.

[0037] In the above, the case where the power storage device charging / discharging unit 204 performs constant current charging on the power storage device unit 202 has been described, but constant voltage charging is also possible, in which case the upper limit values ​​of the charging voltage and charging current can be changed by the power supply control unit 106.

[0038] In addition to the function of charging the power storage device unit 202, the power storage device charge / discharge unit 204 also has a function of discharging the power storage device unit 202 to prevent the power storage device unit 202 from being overcharged.

[0039] Next, FIG. 3 is a diagram illustrating the structure of the imaging device 100 according to this embodiment.

[0040] 3, a main board 301 and an image sensor board 302 are disposed within the housing of the image capturing device 100. The CPU 101 and the power supply unit 107 are mounted on the main board 301. The image sensor 102 is mounted on the image sensor board 302, and the image sensor board 302 is disposed closer to the lens than the main board 301 so that the image sensor 102 can efficiently capture light.

[0041] The imaging sensor board 302 is connected to the main board 301 using flexible printed circuits (FPC), a connector, or the like. This allows control signals from the CPU 101 and power from the imaging power supply unit 1072 to be supplied to the imaging sensor 102. The power storage device unit 202 may be mounted on the main board 301 or on the imaging sensor board 302. For example, if it is mounted on the imaging sensor board 302, the impedance between the imaging sensor 102 and the power storage device unit 202 becomes smaller, which has the advantage of making it easier to supply power from the power storage device unit 202 to the imaging sensor 102.

[0042] Temperature sensor 105a is a temperature sensor arranged on image sensor board 302, temperature sensor 105b is a temperature sensor arranged on main board 301, and temperature sensor 105c is a temperature sensor attached to the housing of image capture device 100. Based on the output data of these temperature sensors 105a to 105c, it is possible to estimate the temperature at any location in image capture device 100.

[0043] Because the power storage device unit 202 deteriorates when exposed to a high-temperature environment, it is important to manage the temperature of the power storage device unit 202. For example, when the power storage device unit 202 is mounted on the imaging sensor board 302, the temperature detected by the temperature sensor 105a is used to monitor the temperature of the imaging sensor 102 so that it does not exceed the usable temperature range. In addition, the temperature detected by the temperature sensor 105a is also used to estimate the temperature of the power storage device unit 202. Furthermore, when the power storage device unit 202 is mounted on the main board 301, the temperature detected by the temperature sensor 105b disposed near the power storage device unit 202 is used to estimate the temperature of the power storage device unit 202. When the temperature sensor 105b cannot be disposed near the power storage device unit 202, the temperature of the power storage device unit 202 on the main board 301 is estimated using the positional relationship between the temperature sensor 105a and the power storage device unit 202, and the temperature detected by the temperature sensor 105a.

[0044] Next, FIG. 4 is a block diagram showing the configuration of the supply source selection unit 203 in this embodiment.

[0045] 4(a) shows the configuration of the power supply source selection unit 203 and its periphery. The power supply source selection unit 203 is configured to switch the impedance of the power supply path (main power path) from the imaging main power supply unit 201 to the imaging sensor 102. The power supply source selection unit 203 is configured to include a main power supply path switching unit 401, a resistor 402, a power storage device path switching unit 403, and a main power supply current detection unit 404. The power supply control unit 106 controls the on / off switching of each switch of the main power supply path switching unit 401 and the power storage device path switching unit 403.

[0046] When the imaging device 100 is in an operating mode in which the maximum power consumption is relatively high, such as global shutter mode, and during imaging operation, the power storage device path switching unit 403 is controlled to be switched on. This control connects the power supply path from the power storage device unit 202 to the imaging sensor 102 (the power storage device path is on), enabling power supply from the power storage device unit 202. Before imaging operation, the power storage device unit 202 is charged in advance so that the voltage of the power storage device unit 202 is higher than the voltage of the imaging main power supply unit 201. Therefore, during imaging operation, power can be supplied to the imaging sensor 102 preferentially from the power storage device unit 202.

[0047] However, when power is supplied from the power storage device unit 202 to the image sensor 102, the voltage of the power storage device unit 202 drops. In addition, due to the equivalent series resistance (ESR) of the power storage device unit 202, the voltage of the power storage device unit 202 drops in proportion to the amount of current drawn from the power storage device unit 202.

[0048] 4(a), as an example of a circuit configuration of the power storage device path switching unit 403, a diode is arranged to prevent charging of the power storage device unit from the imaging main power supply unit 201 when the power storage device path switch is turned on. Such a component also causes a drop in voltage on the power storage device path side.

[0049] When the voltage output from the power storage device path drops, the voltage of the main power supply path and the voltage of the power storage device path become equal in potential at the junction of the path from the imaging main power supply unit 201 via the main power supply path switching unit 401 and the path from the power storage device unit 202. In this state, power is supplied to the imaging sensor 102 preferentially from the path with the lowest impedance. When the main power supply path switching unit 401 is in the pass-through state and the line impedance of the main power supply path from the imaging main power supply unit 201 is sufficiently low, power is supplied preferentially to the imaging sensor 102 from the imaging main power supply unit 201 even if the power storage device path is on.

[0050] One way to solve this problem is to switch the switches so as to limit the current on the main power supply path side. Specifically, each switch in the main power supply path switching unit 401 is controlled so that the impedance is greater than the impedance of the power storage device path, including the ESR of the power storage device unit 202. The main power supply path switching unit 401 controls the switching of each switch so that one of resistors 402a to 402c is arranged in series with the main power supply path. This allows power to be continuously supplied to the image sensor 102 preferentially from the power storage device unit 202 even if the voltage of the power storage device unit 202 drops.

[0051] If the power storage device path is turned on while the power storage device unit 202 is charged with a voltage higher than that of the imaging main power supply unit 201, there is a risk of current flowing back into the output of the imaging main power supply unit 201. For this reason, it is desirable that the imaging main power supply unit 201 or a switch placed in series with the main power supply path be equipped with a backflow prevention function.

[0052] The resistor 402 has a resistor 402a with a different resistance value, a resistor 402b larger than resistor 402a, and a resistor 403c larger than resistor 402b, and the optimum resistor is selected depending on the situation. In Fig. 4(a), four path routes with different impedances are arranged in the main power supply path switching unit 401, but the number is not limited, and the combined impedance of the paths may be changed by combining the switches that are turned on.

[0053] In order to reduce unnecessary loss caused by the resistor 402, it is desirable that the resistance value of the resistor 402 be as small as possible, even when priority is to be given to power supply from the power storage device unit 202. Therefore, at the beginning of any operation mode of the imaging device 100, path A, which has a relatively small resistance value, is turned on.

[0054] However, if the impedance of the power storage device path increases, the impedance of the main power supply path becomes relatively small, and as a result, the necessary power is not supplied from the power storage device unit 202. One example of when the impedance of the power storage device path increases is when the power storage device unit 202 is at a low temperature. When the power storage device unit 202 is in a low temperature state, the ESR tends to increase.

[0055] To address this problem, the control unit 1011 controls the main power supply path switching unit 401 via the power supply control unit 106 based on the temperature detected by the temperature sensor 105, and changes the impedance of the main power supply path. Specifically, the temperature of the power storage device unit 202 is estimated based on the temperature detected by the temperature sensor 105. Control is performed to switch to path B or path C depending on the impedance of the power storage device path expected at the estimated temperature. This allows the power storage device unit 202 to supply the necessary power even if the impedance of the power storage device path increases at low temperatures.

[0056] If path A is set to the first supply mode, path B or path C, which further restricts the current, is called the second supply mode. In this embodiment, switching between three paths is described, but switching between two or more supply modes is also acceptable.

[0057] In addition to the temperature characteristics of the power storage device unit 202, an increase in the impedance of the power storage device path may also be due to an increase in the ESR of the power storage device unit 202 due to degradation, etc. For this reason, it is desirable to measure the impedance of the power storage device path. The impedance of the power storage device path can be calculated by detecting the current in the main power supply path. For this purpose, the power supply source selection unit 203 includes a main power supply current detection unit 404.

[0058] The main power supply current detection unit 404 can calculate the current flowing in the main power supply path from the voltage difference across the resistor 402. If the current during readout of the image sensor 102 is known to be, for example, 3 A, and the current flowing in the main power supply path is 1 A, then 2 A will flow in the power storage device path. This current ratio is determined by the ratio of the impedance of the main power supply path to the impedance of the power storage device path. If the main power supply path in this case is path A, then the impedance of the power storage device path can be calculated as 1 / 2 of resistor A. Control is performed to switch to path B or path C depending on the impedance of the power storage device path calculated in this way. This makes it possible to ensure that the necessary power is supplied from the power storage device unit 202 even if the power storage device unit 202 deteriorates and the impedance of the power storage device path increases.

[0059] In addition to the method of measuring the impedance of the power storage device path by detecting the current in the main power supply path, for example, a power storage device path impedance calculation means may be disposed in the switch in the power storage device path switching unit 403. The impedance of the power storage device path can be measured from the current and voltage flowing through the power storage device path. In another example, a power storage device path impedance calculation means may be disposed in the power storage device charging / discharging unit 204. The impedance of the power storage device path can be measured from the amount of voltage drop in the power storage device unit 202 when discharging at a constant current.

[0060] Increasing the impedance of the main power path also has the disadvantage of increasing loss in the main power path. Furthermore, when the power storage device path is on, power is supplied from the power storage device unit 202 to the image sensor 102 regardless of whether power needs to be supplied from the power storage device unit 202 to the image sensor 102. This causes unnecessary charging and discharging in the power storage device unit 202, resulting in a shorter battery life for the battery 108.

[0061] Therefore, in an operating mode in which the maximum power of the imaging device 100 is relatively small and the imaging device 100 operates within the allowable power of the battery 108 or the USB power supply unit 110, the main power supply path switching unit 401 is controlled to reduce the impedance of the main power supply path. This makes it possible to minimize loss in the main power supply path. Furthermore, because the impedance of the main power supply path is reduced, when the voltage of the main power supply path and the voltage of the power storage device path become the same potential, power is supplied from the imaging main power supply unit 201 to the imaging sensor 102. As a result, unnecessary charging and discharging of the power storage device unit 202 is reduced, and the battery life of the battery 108 can be improved.

[0062] Additionally, the power storage device path switching unit 403 may be configured to be switched off simultaneously with the switching of the main power supply path, thereby controlling the power storage device path to be turned off. This allows the image sensor 102 to operate without consuming the power stored in the power storage device unit 202, and further prevents loss due to unnecessary charging and discharging of the power storage device unit 202.

[0063] The above-mentioned operating modes with relatively low power consumption include, for example, video mode and still image mode, such as single shooting mode, low-speed continuous shooting mode, low-speed readout mode, etc. Furthermore, operating modes with relatively high maximum power consumption of the imaging device 100 include, for example, global shutter mode, high-speed continuous shooting mode, and live view state in high-speed readout mode.

[0064] The main power path switching unit 401 may be configured to be controlled to switch the main power path between readout operations of the image sensor 102 and other periods, regardless of the operating mode of the imaging device 100. For example, the main power path switching unit 401 may be controlled to increase the impedance of the main power path in synchronization with readout operations of the image sensor 102, and to decrease the impedance of the main power path during periods other than readout. By controlling in this manner, it is possible to reduce the current drawn from the battery 108 or USB power supply unit 110 during readout operations and to reduce unnecessary loss during periods other than readout.

[0065] FIG. 4(b) shows a configuration in which the main power supply path switching unit 401 is replaced with a main power supply current limiting unit 406. The main power supply current limiting unit 406 limits the current output from the main power supply current limiting unit 406 so that it does not exceed a current threshold determined by the power supply control unit 106. FIG. 4(b) shows an example in which the main power supply current limiting unit 406 is a component of the power supply source selection unit 203, but the imaging main power supply unit 201 may also be provided with a function equivalent to that of the main power supply current limiting unit 406. Like the main power supply path switching unit 401 shown in FIG. 4(a), the main power supply current limiting unit 406 can also change the limit current based on information from a temperature sensor. Also, like the main power supply path switching unit 401 shown in FIG. 4(a), the main power supply current limiting unit 406 can also change the current threshold depending on the operation mode of the imaging device 100.

[0066] A state in which the current output from the main power path is controlled to a first value is referred to as a first supply mode, and a state in which the current output from the main power path is controlled to a second value lower than the first value is referred to as a second supply mode. The first supply mode can also be referred to as a state in which the current limit on the main power path is weak. The second supply mode can also be referred to as a state in which the current limit on the main power path is strong. As described above, the first supply mode and the second supply mode are switched depending on the operation mode of the imaging device 100. The control for switching between the first supply mode and the second supply mode depending on information from the temperature sensor 105 has also been described. The control for switching between the first supply mode and the second supply mode by the control unit 1011 depending on the ESR has also been described. This switching operation makes it possible to reduce the maximum current of the battery 108 or the USB power supply unit 110 while suppressing loss in the imaging power supply unit 1072.

[0067] The state in which the current of the main power supply path is not limited and the state in which the current is limited may be switched as a first supply mode and a second supply mode, or the supply mode may be switched so as to have two or more different limit values.

[0068] 4B may monitor the state of the battery 108, and switch the supply mode depending on the state of the battery 108. For example, if the voltage of the battery 108 is lower than a predetermined value, the second supply mode may be selected. In another example, if the current of the battery 108 is higher than a predetermined value, the second supply mode may be selected. In another example, if the internal resistance of the battery 108 is higher than a predetermined value, the second supply mode may be selected. This limits the output current of the imaging main power supply unit 201 so as not to exceed the allowable current of the battery 108, and allows the imaging sensor 102 to operate in combination with power from the power storage device unit 202.

[0069] 4(a) and 4(b), a configuration has been described in which the impedance of the main power supply path is changed depending on the temperature or ESR of the power storage device unit 202. Here, if the power storage device unit 202 is in an excessively low temperature state, even if the impedance of the main power supply path is set to the maximum, the impedance of the power storage device path becomes even greater, and power is preferentially supplied from the imaging main power supply unit 201 to the imaging sensor 102. At this time, there is a risk that the allowable power of the battery 108 or USB power supply unit 110 will be exceeded, causing a system shutdown.

[0070] To solve this problem, the control unit 1011 predicts the power to be supplied from the imaging main power supply unit 201 to the imaging sensor 102 based on information from the temperature sensor 105, and controls the imaging device 100 to prohibit shooting operations if the power exceeds a predetermined value.

[0071] Furthermore, if the impedance of each path that serves as the power supply path for the image sensor 102 becomes excessively large, the voltage may fall below the operating voltage of the image sensor 102 due to a voltage drop caused by the impedance.

[0072] To solve this problem, the control unit 1011 predicts the voltage drop of the image sensor 102 from information from the temperature sensor 105, and controls the image capturing device 100 to prohibit shooting if the voltage drop exceeds a predetermined value.

[0073] In the above example, the control unit 1011 is described as prohibiting the image capturing operation of the image capturing device 100 based on information from the temperature sensor 105. However, the control unit 1011 may also prohibit the image capturing operation by predicting the ESR of the power storage device unit 202. In this case, the control unit 1011 predicts the power to be supplied from the image capturing main power supply unit 201 to the image capturing sensor 102 based on the ESR of the power storage device unit 202, and controls the image capturing operation of the image capturing device 100 to be prohibited if the predicted power exceeds a predetermined value. The control unit 1011 also predicts the voltage drop of the image capturing sensor 102 based on the ESR of the power storage device unit 202, and controls the image capturing operation of the image capturing device 100 to be prohibited if the voltage drop exceeds a predetermined value.

[0074] For example, if the still image mode requires a higher maximum power than the video mode and is based on the assumption that power from the power storage device unit 202 is supplied to the image sensor 102, then imaging operations in only the still image mode are prohibited when the impedance of the power storage device unit 202 becomes large. Alternatively, even within the still image mode, imaging operations in the high-speed continuous shooting mode, high-speed readout mode, and global shutter mode, which are based on the assumption that more power is supplied from the power storage device unit 202 to the image sensor 102, may be prohibited.

[0075] Next, FIGS. 5A to 5C are flowcharts showing the control of the imaging power supply unit 1072 by the control unit 1011 via the power supply control unit 106 in this embodiment.

[0076] For example, when a user performs an operation such as pressing the power button of the imaging device 100, in step S501, the control unit 1011 performs a startup process of the imaging device 100. In the startup process of the imaging device 100, a start-up operation of the power supply unit 107 is performed.

[0077] Next, in step S502, the control unit 1011 performs initialization processing of the main power supply path switching unit 401. In the initialization processing, control is performed so that the main power supply path is in a pass-through state. This makes it possible to prevent unnecessary loss from occurring in the resistor 402 in the live view state.

[0078] Next, in step S503, the control unit 1011 disables the power storage device path. It controls the power storage device path switching unit 403 to turn off the switch so that power is not supplied from the power storage device unit 202 to the image sensor 102. This prevents loss due to unnecessary charging and discharging of the power storage device unit 202 in the live view state.

[0079] Next, in step S504, the control unit 1011 performs imaging startup processing and starts operation in a live view state. In this live view state, power is supplied from the imaging main power supply unit 201 to the imaging sensor 102 via a pass-through path.

[0080] Next, in step S505, the control unit 1011 predicts the ESR of the power storage device unit 202. First, it controls the main power supply path to be path B. It also controls the power storage device path switching unit 403 to be switched on so that the power storage device path is enabled. At the same time, the power storage device charging / discharging unit 204 charges the power storage device unit 202 so that the output voltage is higher than the output voltage of the imaging main power supply unit 201. Next, it causes the imaging sensor 102 to operate so that the current consumption is known and constant. At this time, the main power supply current detection unit 404 detects the current flowing in the main power supply path from the voltage difference across resistor 402b. The detected main power supply path current is sent to the control unit 1011. The control unit 1011 calculates the current in the power storage device path using the following formula.

[0081] Storage device path current = Image sensor current consumption - Main power supply path current (Equation 1) Next, the ESR of the power storage device section 202 is predicted by the following formula using the ratio of the power storage device path current to the main power supply path current.

[0082] Energy storage device ESR = Resistance B × (Main power supply path current / Electric storage device path current) (Equation 2) By detecting the current in the main power supply path in this way, it is possible to predict the ESR of the power storage device section 202.

[0083] Although the current consumption of the image sensor 102 is used to predict the ESR of the power storage device section 202 in the above description, a dedicated test circuit that generates a load that results in a known current consumption may be provided separately from the image sensor. Also, although the method of using current detection of the main power supply path to predict the ESR of the power storage device section 202 has been described, the ESR prediction is not limited to the above means and formula, and other means and formulas may be used.

[0084] When the prediction of the ESR of the power storage device unit 202 is completed, the switch is controlled to put the main power path into a pass-through state and to disable the power storage device path.

[0085] Next, in step S506 , the control unit 1011 estimates the temperature of the power storage device unit 202 based on the output data of the temperature sensor 105 .

[0086] Next, in step S507, the control unit 1011 determines whether the power storage device unit 202 has deteriorated.

[0087] 6 and 7 are diagrams for explaining the deterioration determination of the power storage device unit 202. FIG.

[0088] FIG. 6(a) shows the temperature characteristics of the power storage device unit 202. The power storage device unit 202 exhibits a characteristic in which the ESR increases as the temperature decreases. Also, FIGS. 6(b) and 6(c) show the degradation characteristics of the power storage device unit 202. Even at the same applied voltage, the higher the temperature, the more degradation progresses, and the ESR increases as a result of the degradation. Also, even at the same temperature, the higher the applied voltage, the more degradation progresses, and the ESR increases as a result of the degradation. In other words, simply identifying the ESR does not tell whether it is due to the temperature characteristics of the power storage device unit 202 or the result of the progression of degradation.

[0089] 7 is a diagram showing regions for each degree of deterioration of the power storage device unit 202, and the control unit 1011 uses this diagram to determine the deterioration of the power storage device unit 202. When the temperature is high, the ESR of the power storage device unit 202 tends to be small, but if the ESR is large despite this, it means that deterioration is progressing. Also, when the temperature is low, the ESR of the power storage device unit 202 tends to be high, so even if the ESR is somewhat large, it can be determined that this is due to temperature characteristics.

[0090] 7, the control unit 1011 uses the ESR and temperature information acquired in steps S505 and S506 to calculate the region in Fig. 7 where the ESR is located, and calculates the degree of degradation based on that. As another example, an ESR degradation threshold may be set for each temperature, and the degree of degradation may be calculated by comparing the acquired ESR with the ESR degradation threshold.

[0091] Next, in step S508, the control unit 1011 determines whether the operation mode of the imaging device 100 is the moving image mode. If the operation mode of the imaging device 100 is the still image mode, the process proceeds to step S509. If the operation mode of the imaging device 100 is the moving image mode, the process proceeds to step S528.

[0092] Here, the video mode is an example of a mode in which the maximum power required for shooting in that operating mode can be fully covered by the power supplied by the battery 108 or the USB power supply unit 110. In the case of a relatively low-power still image mode, such as a low-speed continuous shooting mode or a low-speed readout mode, the process may proceed to step S528 instead of step S509.

[0093] In step S509, the control unit 1011 determines whether the power storage device unit 202 is usable or not, by referring to the degree of deterioration of the power storage device unit 202 determined in step S507.

[0094] If the deterioration of the power storage device unit 202 is extremely advanced, image capture is prohibited. This is because it is predicted that the system will not function properly even if the main power path switching unit 401 is controlled to maximize the impedance of the main power path. For example, this situation may occur when a large amount of power is supplied from the image capture main power supply unit 201 to the image sensor 102, exceeding the allowable power of the battery 108 or the USB power supply unit 110 and causing a system shutdown. In another case, the impedance of each power path for the image sensor 102 is large, and the voltage drop due to this impedance is predicted to cause the voltage to fall below the operating voltage of the image sensor 102. If the deterioration level is such that such a situation actually occurs, proceed to step S529. If the deterioration level is other than this, proceed to step S510.

[0095] In step S510, the control unit 1011 determines the temperature of the power storage device unit 202. The control unit 1011 compares the estimated temperature of the power storage device unit 202 acquired in step S506 with the temperature (Ta) at which deterioration of the power storage device unit 202 progresses rapidly. If the estimated temperature of the power storage device unit 202 is lower than Ta, that is, if there is a low risk that deterioration of the power storage device unit 202 will progress even if a high voltage is applied to the power storage device unit 202, the control unit 1011 proceeds to step S511.

[0096] In step S511, the control unit 1011 changes the charging voltage at which the power storage device charging / discharging unit 204 charges the power storage device unit 202. If the power storage device charging / discharging unit 204 charges the power storage device unit 202 using constant current charging, the charge completion voltage is changed. In step S511, the temperature of the power storage device unit 202 is high, indicating a high risk of deterioration, so the charging voltage is set low. In this way, by lowering the charging voltage of the power storage device unit 202 based on information from the temperature sensor 105, it is possible to suppress deterioration of the power storage device unit 202. Next, the process proceeds to step S513.

[0097] In step S512, the control unit 1011 also changes the charging voltage used to charge the power storage device unit 202 from the power storage device charge / discharge unit 204, as in step S511. In step S512, the charging voltage is set high because the temperature of the power storage device unit 202 is low and the risk of deterioration is low. If the operating mode of the imaging apparatus 100 is one that assumes that power is supplied from the power storage device unit 202 to the imaging sensor 102, the voltage must reach a predetermined voltage that is at least higher than the output voltage of the imaging main power supply unit 201 during imaging. Therefore, when the temperature is low and there is little risk of deterioration, maintaining the charging voltage of the power storage device unit 202 high makes it possible to smoothly transition to imaging operation without taking unnecessary charging time during imaging. Next, the process proceeds to step S513.

[0098] In step S513, the control unit 1011 changes the charging current used by the power storage device charging / discharging unit 204 to charge the power storage device unit 202. If the power storage device charging / discharging unit 204 charges the power storage device unit 202 using constant current charging, the control unit 1011 changes the output current of the power storage device charging / discharging unit 204. The power storage device charging / discharging unit 204 can be set to a high-output mode, which provides a relatively large output current, or a low-output mode, which provides a relatively small output current. In step S513, the power storage device charging / discharging unit 204 is set to the high-output mode. This allows, for example, if the operating mode of the imaging device 100 is set to video mode and the charging voltage of the power storage device unit 202 is set low to prevent deterioration, high-speed charging up to the target charging voltage when the operating mode is changed to still image mode. Furthermore, during this period from when the mode is switched to when image capture begins, the current consumption of the imaging device 100 is relatively small, and there is a margin in the allowable power of the battery 108 or the USB power supply unit 110. Therefore, there is no problem even if the power storage device charge / discharge unit 204 is set to the high output mode at this timing.

[0099] Next, in step S514, the control unit 1011 determines whether or not SW1 has been pressed by the user. SW1 corresponds to the operation immediately before the user's release operation, such as half-pressing the release button. When SW1 is pressed, the imaging device 100 is in a shooting preparation state where it can immediately transition to shooting operation once SW2 is pressed. In response to the SW1 operation, well-known shooting preparation processing such as AF processing and AE processing is executed. If SW1 has not been pressed, the process proceeds to step S515. If SW1 has been pressed, the process proceeds to step S516.

[0100] In step S515, the control unit 1011 determines whether or not a user operation corresponding to a change in the operation mode of the imaging device 100 has been performed. If the operation mode of the imaging device 100 has not been changed, the process returns to step S514. If the operation mode of the imaging device 100 has been changed, the process returns to step S505. If the user has performed an operation to shut down the imaging device 100, such as turning off the main power switch, the process proceeds to step S531.

[0101] In step S516, the control unit 1011 sets the charging voltage of the power storage device unit 202 to a voltage that allows power to be supplied from the power storage device unit 202 to the imaging sensor 102. At this time, if the charging voltage was set in step S512 to the same voltage as the charging voltage of the power storage device unit 202 set in step S516, there is no need to reset the charging voltage of the power storage device unit 202 in step S516. If the charging voltage of the power storage device unit 202 was set low in step S511 to prevent deterioration, the charging voltage of the power storage device unit 202 is set in step S516 to a voltage that allows power to be supplied from the power storage device unit 202 to the imaging sensor 102. This makes it possible to minimize the time for which the voltage is increased, preventing deterioration, and enabling imaging operations even when the temperature of the power storage device unit 202 is high.

[0102] Next, in step S517, the control unit 1011 determines whether charging of the power storage device unit 202 is complete. The control unit 1011 compares the voltage set in step S516 with the voltage of the power storage device unit 202 to determine whether charging is complete. Alternatively, the control unit 1011 may monitor the charging current and determine whether charging of the power storage device unit 202 is complete based on whether the charging current has stopped. If charging of the power storage device unit 202 is not yet complete, the process proceeds to step S518. If charging of the power storage device unit 202 is complete, the process proceeds to step S519.

[0103] In step S518, the control unit 1011 displays a busy message in addition to the live view display. Here, the busy message means that the imaging device 100 is unable to perform a shooting operation. By checking the busy message, the user can know whether or not shooting is possible. After the busy message is displayed, the process returns to step S517. This is repeated until charging of the power storage device unit 202 is complete, but if it is determined in step S517 that charging of the power storage device unit 202 is complete, the busy message is canceled.

[0104] In step S519, the control unit 1011 determines whether or not SW2 has been pressed by the user. SW2 corresponds to the user's release instruction operation, such as fully depressing the release button. If SW2 has not been pressed, the process proceeds to step S527. If SW2 has been pressed, the process proceeds to step S520.

[0105] In step S520, the control unit 1011 changes the charging current used to charge the power storage device unit 202 from the power storage device charging / discharging unit 204. If the power storage device charging / discharging unit 204 charges the power storage device unit 202 using constant current charging, the control unit 1011 changes the output current of the power storage device charging / discharging unit 204. In step S520, the power storage device charging / discharging unit 204 is set to low output mode. This makes it possible to reduce the amount of power taken from the battery 108 or the USB power supply unit 110 during shooting operations. In low output mode, a charging current is desirable that allows the voltage of the power storage device unit 202, which has dropped in a high-speed continuous shooting mode with a short shooting interval, to recover within the time until the next shooting operation.

[0106] Next, in step S521, the control unit 1011 sets the main power path to a path other than the pass-through state. Here, the control unit 1011 determines the main power path based on the output data of each of the temperature sensors 105a to 105c. The lower the temperature of the power storage device unit 202, the higher the ESR of the power storage device unit 202. Therefore, by controlling the impedance of the main power path to increase as the temperature decreases, it becomes possible to supply power from the power storage device unit 202 to the image sensor 102 regardless of the temperature of the imaging apparatus 100. The ESR of the power storage device unit 202 also increases due to deterioration. Therefore, the path to be changed for the main power path may be determined based on the ESR of the power storage device unit 202 predicted in step S505. If the degree of deterioration of the ESR is within an acceptable range, it becomes possible to supply power from the power storage device unit 202 to the image sensor 102 regardless of the ESR value.

[0107] Next, in step S522, the control unit 1011 enables the power storage device path and controls the power storage device path switching unit 403 to turn on the switch so that power is supplied from the power storage device unit 202 to the image sensor 102. This makes it possible to supply power from the power storage device unit 202 to the image sensor 102 during image capture.

[0108] Next, in step S523, the control unit 1011 performs an image capture operation. First, because the voltage of the power storage device unit 202 is higher than the voltage of the imaging main power supply unit 201, power is supplied from the power storage device unit 202 to the imaging sensor 102. When the voltage of the power storage device unit 202 drops and becomes the same as the voltage of the imaging main power supply unit 201, power is supplied to the imaging sensor 102 from either the main power supply path or the power storage device path, whichever has the smaller impedance. In step S521, control is performed so that the impedance of the power storage device path is smaller than that of the main power supply path. Therefore, even if the voltage of the power storage device unit 202 drops, power is preferentially supplied to the imaging sensor 102 from the power storage device unit 202. As a result, even when the imaging apparatus 100 is in an operating mode with a high maximum power consumption, such as global shutter mode, it is possible to reduce the instantaneous power drawn from the battery 108 or USB power supply unit 110.

[0109] Next, in step S524, the control unit 1011 determines whether or not SW2 has been released. If SW2 continues to be pressed, the process returns to step S523 and the next shooting operation is performed. If SW2 has been released, the shooting operation is stopped and the process proceeds to step S525.

[0110] In step S525, the control unit 1011 performs initialization processing of the main power supply path switching unit 401 in the same manner as in step S502.

[0111] Next, in step S526, the control unit 1011 invalidates the power storage device path in the same manner as in step S503.

[0112] Next, in step S527, the control unit 1011 determines whether SW1 has been released. If SW1 continues to be pressed, the process returns to step S519 to determine whether SW2 has been pressed again. If SW1 and SW2 have been released, the shooting preparation state is stopped and the process returns to step S510.

[0113] In step S528, the control unit 1011 sets the charging voltage of the power storage device unit 202 low. For example, in an operating mode such as video mode, in which the power supplied by the battery 108 or the USB power supply unit 110 is sufficient to cover the maximum power of the image sensor 102, the charging voltage of the power storage device unit 202 is set low even during image capture. This prevents deterioration of the power storage device unit 202. In particular, when the operating mode of the image capture device 100 is video mode, image capture often continues for a long period of time, which increases the internal temperature of the image capture device 100 and the temperature of the power storage device unit 202. In an operating mode in which the temperature of the power storage device unit 202 is likely to increase, it is important to set the charging voltage of the power storage device unit 202 low to prevent deterioration. Furthermore, even if the charging voltage of the power storage device unit 202 is set low, when the mode is switched to still image mode, the charging current is increased in step S513 to charge the power storage device unit 202 quickly. This allows for a rapid transition to image capture. Next, proceed to step S530.

[0114] In step S529, the control unit 1011 displays on the display unit 103 to the user that the current operation mode cannot be used due to deterioration of the power storage device unit 202. This allows the user to know that this mode is not available and that the power storage device unit 202 has deteriorated. For example, if the user who sees this message wishes to continue using this operation mode, they can take measures such as replacing the power storage device unit 202. Also, in step S529, a display may be displayed that guides the user to an available alternative mode, allowing the user to continue shooting in the alternative mode. Next, the process proceeds to step S530.

[0115] In step S530, the control unit 1011 determines whether or not a user operation corresponding to a change in the operation mode of the imaging device 100 has been performed, as in step S515. If the operation mode of the imaging device 100 has not been changed, S530 is repeated while maintaining the live view state, and a mode change is awaited. If the operation mode of the imaging device 100 has been changed, the process returns to step S505. If the user has performed an operation to shut down the imaging device 100, such as turning off the main power switch, the process proceeds to step S531.

[0116] In step S531, the control unit 1011 sets the charging voltage of the power storage device 202 to 0 V. This makes it possible to suppress deterioration of the power storage device unit 202 when the imaging apparatus 100 is powered off.

[0117] Next, in step S532, the control unit 1011 performs a shutdown process for the image capture device 100. In the shutdown process for the image capture device 100, in addition to the shutdown process for each device, the power supply unit 107 is also shut down.

[0118] For example, if the target voltage of the power storage device unit 202 becomes lower than the current voltage in step S511, step S528, or step S531, the output of the power storage device charging / discharging unit 204 may be stopped and the target voltage may be reached by natural discharge. In this case, the frequency with which the power stored in the power storage device 202 becomes ineffective is reduced, which is advantageous for the battery life of the battery 108. On the other hand, the voltage is applied for a longer period of time, which may cause deterioration. For this reason, the power storage device charging / discharging unit 204 may be provided with a discharge function, and discharge may be performed until the target voltage is reached. In this case, the voltage of the power storage device unit 202 drops quickly, which may prevent deterioration of the power storage device unit 202.

[0119] 8(a) and (b) are diagrams illustrating an example of switch settings of the main power supply path switching unit 401. FIG.

[0120] Here, the still image mode requires a relatively high maximum power, and is based on the premise that the imaging sensor 102 is operated with power supplied from the power storage device unit 202. On the other hand, the moving image mode requires a relatively low maximum power, and is based on the premise that the imaging sensor 102 is operated without power being supplied from the power storage device unit 202 to the imaging sensor 102. Furthermore, among the still image modes, the global shutter mode in particular requires a high maximum power, and is based on the premise that the imaging device 100 is operated with more power supplied from the power storage device unit 202 to the imaging sensor 102.

[0121] FIG. 8(a) is a switch setting table for the main power supply path switching unit 401 when switching the main power supply path depending on the temperature.

[0122] When the temperature is 20°C or higher, path B and path C are turned on in global shutter mode. At this time, the impedance of the main power supply path is the combined resistance of resistor 402b and resistor 402c arranged in parallel. Also, in still image modes other than global shutter mode, path A and path C are turned on. At this time, the impedance of the main power supply path is the combined resistance of resistor 402a and resistor 402c arranged in parallel. And in video mode or still image mode, the pass-through state is set in the live view state.

[0123] In this way, the more power is supplied from the power storage device unit 202 to the image sensor 102 in an operating mode, the higher the current limit on the main power supply path should be. Conversely, in operating modes where little power supply from the power storage device unit 202 is required, the limit on the main power supply path can be relaxed so that more power than necessary is not supplied from the power storage device unit 202, thereby reducing loss in the main power supply path. In addition, it is possible to reduce loss due to charging and discharging of the power storage device unit 202.

[0124] Furthermore, when the temperature is below 20°C but above 0°C, the switch state is changed to increase the impedance of the main power path in each mode. This is because the ESR of the power storage device unit 202 increases at low temperatures, and increasing the impedance of the main power path allows power to be supplied from the power storage device unit 202 to the image sensor 102. Conversely, when the temperature is sufficiently high, the restrictions on the main power path are relaxed, making it possible to reduce losses in the main power path and losses due to charging and discharging of the power storage device unit 202. Furthermore, even in video mode or still image mode, the assumption is that in live view mode the image sensor 102 will operate without power being supplied from the power storage device unit 202 to the image sensor 102, so the pass-through state is fixed regardless of temperature.

[0125] Similarly, when the temperature is below 0°C, the switch state is changed so as to further increase the impedance of the main power path in each mode.

[0126] FIG. 8B is a switch setting table for the main power supply path switching unit 401 when the main power supply path is switched based on the ESR of the power storage device unit 202.

[0127] When estimating the ESR of the power storage device section 202, path B is turned on regardless of the operating mode or other settings of the imaging apparatus 100. The control section 1011 can predict the ESR of the power storage device section 202 from the known resistance B and the operating power of the imaging sensor, as well as information from the main power supply current detection section 404 when the imaging sensor is operated. Depending on the predicted ESR, the switch state of the main power supply path switching section 401 is changed during imaging.

[0128] When the ESR of the power storage device unit 202 is less than 100 mΩ, path B and path C are turned on in global shutter mode. At this time, the impedance of the main power supply path is the combined resistance of resistors 402b and 402c arranged in parallel. In still image modes other than global shutter mode, path A and path C are turned on. At this time, the impedance of the main power supply path is the combined resistance of resistors 402a and 402c arranged in parallel. In both video and still image modes, the pass-through state is established in live view mode. Thus, the more power the power storage device unit 202 supplies to the image sensor 102 in an operating mode, the higher the current limit on the main power supply path. Conversely, in operating modes where little power supply from the power storage device unit 202 is required, the more relaxed the limit on the main power supply path is so that more power is not supplied from the power storage device unit 202 than necessary. This reduces loss in the main power supply path. Additionally, it reduces loss due to charging and discharging the power storage device unit 202.

[0129] Furthermore, when the ESR of the power storage device unit 202 is equal to or greater than 100 mΩ and less than 400 mΩ, the switch state is changed to increase the impedance of the main power supply path in each mode. Because the ESR of the power storage device unit 202 is increased, increasing the impedance of the main power supply path allows power to be supplied from the power storage device unit 202 to the image sensor 102. Conversely, when the ESR of the power storage device unit 202 is sufficiently low, relaxing the restrictions on the main power supply path can reduce losses in the main power supply path and losses due to charging and discharging of the power storage device unit 202. Furthermore, even in video mode or still image mode, in the live view state, it is assumed that the power storage device unit 202 will operate without supplying power to the image sensor 102, so the pass-through state is fixed regardless of the ESR of the power storage device unit 202.

[0130] Similarly, when the ESR of the power storage device section 202 is equal to or greater than 400 mΩ and less than 600 mΩ, the switch state is changed so as to further increase the impedance of the main power supply path in each mode.

[0131] When the ESR of the power storage device unit 202 exceeds 600 mΩ, shooting in global shutter mode is prohibited. This is because it is predicted that the system will not function properly even if only path C is turned on to maximize the impedance of the main power supply path. For example, this situation could occur when a large amount of power is supplied from the main power supply unit 201 to the image sensor 102, exceeding the allowable power of the battery 108 or USB power supply unit 110 and causing a system shutdown. In another case, the impedance of each power supply path for the image sensor 102 is large, and the voltage drop due to this impedance is predicted to cause the voltage to fall below the operating voltage of the image sensor 102. It is possible to prohibit shooting operations according to the ESR before such a predicted situation actually occurs.

[0132] FIG. 8(c) is a diagram illustrating the settings of the power storage device charging / discharging unit 204 in each operation mode.

[0133] During image capture in global shutter mode, the charging voltage of the power storage device unit 202 is set to 5.0 V. For example, if the output voltage of the imaging main power supply unit 201 is 4.5 V, the voltage of the power storage device path will be higher than that of the main power supply path, and power will be supplied to the imaging sensor 102 from the power storage device unit 202 with higher priority. Furthermore, in the live view state, if the estimated temperature of the power storage device unit 202 is higher than Ta, the charging voltage is lowered to 2.0 V. This makes it possible to suppress deterioration of the power storage device.

[0134] If the charging voltage were set to 0V, and the user were to start shooting in this state, it would take a long time to charge from 0V to 5.0V, resulting in a prolonged period of time during which the user would be unable to shoot. To solve this problem, charging is performed within a range that does not significantly accelerate deterioration, even when the temperature is higher than Ta. Furthermore, even when the estimated temperature of the power storage device unit 202 is lower than Ta, the voltage is lowered to around 4.5V to prevent deterioration. The time required to charge from 4.5V to 5.0V is short, and this is thought to have almost no impact on the user.

[0135] During shooting in a still image mode other than the global shutter mode, the charging voltage of the power storage device unit 202 is set to 4.5 V. In a still image mode other than the global shutter mode, less power needs to be supplied from the power storage device unit 202 to the image sensor 102 than in the global shutter mode, so the charging voltage of the power storage device unit 202 is set lower than in the global shutter mode. In this way, setting the charging voltage of the power storage device unit 202 to an optimal voltage depending on the operating mode is important in suppressing deterioration of the power storage device unit 202. Furthermore, in the live view state, when the estimated temperature of the power storage device unit 202 is higher than Ta, the charging voltage is lowered to 2.0 V, as in the global shutter mode.

[0136] In video mode, regardless of whether the camera is in shooting mode or in live view mode, the charging voltage of the power storage device unit 202 is set to a uniform 2.0 V. In this way, in a mode that is premised on operation without supplying power from the power storage device unit 202 to the image sensor 102, deterioration of the power storage device unit 202 can be suppressed by lowering the charging voltage of the power storage device unit 202. The reason why the charging voltage of the power storage device unit 202 is not set to 0 V here is to shorten the charging time of the power storage device unit 202 as much as possible when the user switches to still image mode and immediately tries to start shooting.

[0137] Furthermore, when measuring ESR, the charging voltage of the power storage device unit 202 is set to 4.5 V. Here, the setting of 4.5 V means a voltage setting that is approximately the same as the output voltage of the imaging main power supply unit 201, and this makes it possible to calculate the impedance ratio of each path from the current ratio of each path.

[0138] Furthermore, when the power supply of the imaging device 100 is turned off, since this state is likely to continue for a longer period of time, the charging voltage of the power storage device unit 202 is set to 0.0 V. This makes it possible to suppress deterioration of the power storage device unit 202 while the power supply of the imaging device 100 is off.

[0139] For example, when the operating mode is switched from video mode to global shutter mode, the charging voltage is changed from 2.0 V to 5.0 V. If the charging current is small at this time, it will take a long time for the user to switch modes and become able to capture images. Therefore, in the live view state from when the operating mode is switched to when capture begins, the power storage device charging / discharging unit 204 is set to high-power mode, and the power storage device unit 202 is charged with a charging current of 300 mA. Furthermore, if capture begins while still in high-power mode, the charging current of the power storage device unit 202 will increase the power drawn from the battery 108 or the USB power supply unit 110. Therefore, before capture begins, the power storage device charging / discharging unit 204 is set to low-power mode, and the power storage device unit 202 is charged with a charging current of 100 mA. The switching from high-power mode to low-power mode only needs to be performed before capture begins; for example, the switching to low-power mode may be performed when charging is completed using a means such as voltage monitoring. In another example, after the operation mode and the charging voltage of the power storage device unit 202 are changed, the mode may be switched to the low output mode after a predetermined time corresponding to the difference in the charging voltage of the power storage device unit 202 has elapsed.

[0140] 9 is a timing chart showing a typical operation of the image capturing apparatus 100 according to this embodiment. Note that this timing chart is an example of the operation, and the image capturing apparatus 100 operates appropriately in response to user operations.

[0141] 9, from the top, 7A shows a user operation on the imaging device 100, and 7B shows the operation of the imaging device 100 in response to the user operation of 7A. 7C shows the amount of current when the imaging sensor 102 operates. 7D shows the temperature change of the power storage device unit 202 calculated from the detection value of the temperature sensor 105.

[0142] 7E indicates whether the main power supply path switching unit 401 is to prioritize power supply from the imaging main power supply unit 201 or the power storage device unit 202. When the level of 7E is Low (pass-through), power is supplied preferentially from the imaging main power supply unit 201 to the imaging sensor 102. When the level of 7E is High (resistance ON), power is supplied preferentially from the power storage device unit 202 to the imaging sensor 102.

[0143] 7F indicates the amount of current supplied from the imaging main power supply unit 201. This amount of current must not exceed the maximum power of the battery 108 or the USB power supply unit 110. 7G indicates the amount of current supplied from the power storage device unit 202. 7H indicates the voltage charged to the power storage device unit 202. 7I indicates the maximum amount of current when charging the power storage device unit 202.

[0144] The operation will be described below in accordance with the user's operation on the imaging device 100.

[0145] The user turns on the power lever to start the imaging device 100 (T701). It is assumed that the imaging device 100 is initially set to operate in global shutter mode. The imaging device 100 starts initialization (7B), and the current value of the imaging sensor 102 increases (7C). Once the current value of the imaging sensor 102 stabilizes, the main power path switching unit 401 switches (7F). The imaging sensor 102 operates using power from the power storage device unit 202, and a deterioration determination of the power storage device unit 202 is performed. In this embodiment, it is assumed that the power storage device unit 202 is not deteriorated. Once the deterioration determination is complete, the device transitions to a live view state. In the live view state, the charging voltage of the power storage device unit 202 is set to a voltage (approximately 4.5V) that is unlikely to deteriorate when the temperature is not high and that does not take long to charge (7H). In this embodiment, it is assumed that the imaging device 100 is set to a still image, global shutter mode by user operation.

[0146] Next, the user presses SW1 to perform an AF operation (T702). At this time, the image capture device 100 enters a shooting standby state, and the power storage device unit 202 is charged to a voltage (approximately 5.0 V) that can supply sufficient power to the image sensor 102 (7H).

[0147] After that, the user presses SW2, which initiates the image capture operation (T703). Because image capture is performed in global shutter mode, the current consumption of the image capture sensor 102 momentarily increases (7C). At this time, the maximum charging current of the power storage device unit 202 is reduced (7I). Specifically, the maximum charging current is reduced from 300 mA to approximately 100 mA. Furthermore, the main power supply path switching unit 401 is switched (7E). Specifically, path B is turned ON from the pass-through state, changing to a path via resistor 402b (approximately 200 mΩ). By performing the above operations, it becomes possible to supply a momentarily large current to the image capture sensor 102 from the power storage device unit 202. Furthermore, the current from the image capture main power supply unit 201 does not increase, enabling operation while maintaining the rated current of the battery 108 and USB power supply unit 110.

[0148] When the user releases SW1 and SW2, the shooting operation ends and the camera returns to the live view state (T704). At this point, the maximum charging current of the power storage device unit 202 is increased (7I). Specifically, it is increased from 100 mA to approximately 300 mA. Furthermore, the main power path switching unit 401 is switched (7E). Specifically, the path via resistor 402b (approximately 200 mΩ) of path B is changed to a pass-through state.

[0149] Next, suppose the user switches modes, changing from still image mode to video mode (T705). In this embodiment, the average current consumption of the image sensor 102 in video mode is high, but does not momentarily exceed that in still image mode (7C). Therefore, there is no problem if the power of the power storage device unit 202 is not used. The charging voltage of the power storage device unit 202 (to approximately 2.0 V) is reduced (7H), and the maximum charging current to the power storage device unit 202 is also reduced (7I). Specifically, the maximum charging current is reduced from 300 mA to approximately 100 mA.

[0150] On the other hand, since the average current is large in the moving image mode, the internal temperature of the imaging device 100 rises, and so does the temperature of the built-in power storage device unit 202. If moving images are taken for a certain period of time, the temperature will exceed Ta (7D).

[0151] The user's operation ends video capture and switches to still image mode (T706). The temperature of the power storage device unit 202 exceeds Ta (7D). At this time, the charging voltage of the power storage device unit 202 (approximately 2.0 V) is not increased (7H) in order to prevent deterioration of the power storage device unit 202.

[0152] Next, suppose the user presses SW1 and SW2 simultaneously (T707). Here, the power storage device unit 202 charges up to a voltage (approximately 5.0 V) that can adequately support the power of the image sensor 102 (7H). However, because the temperature of the power storage device unit 202 is high, the charging voltage of the power storage device unit 202 is low, and the charging time becomes longer. During this time, the image capture device 100 displays a busy message to notify the user that image capture in global shutter mode is not possible. In other words, the image capture device 100 indirectly notifies the user that a certain operation is not possible due to the temperature rise of the power storage device unit 202.

[0153] When charging of the power storage device unit 202 is completed, the maximum charging current of the power storage device unit 202 is reduced (7I). Specifically, the maximum charging current is reduced from 300 mA to approximately 100 mA. The main power supply path switching unit 401 is switched (7E). Specifically, path B is turned ON from the pass-through state, changing to a path via resistor 402b (approximately 200 mΩ). By performing the above operations, it becomes possible to supply a momentary large current to the image sensor 102 from the power storage device unit 202. Furthermore, the current from the image capture main power supply unit 201 does not increase, making it possible to operate while maintaining the rated current of the battery 108 and USB power supply unit 110.

[0154] When the user releases SW1 and SW2, shooting ends and the system returns to live view mode (T708). The maximum charging current of the power storage device unit 202 is increased (7I). Specifically, it is increased from 100 mA to approximately 300 mA. Furthermore, the main power path switching unit 401 is switched (7E). Specifically, the path via resistor 402b (approximately 200 mΩ) of path B is changed to a pass-through state.

[0155] When the temperature of the power storage device unit 202 has dropped sufficiently, operations T709 and T710 are the same as those T703 and T704.

[0156] If there is no user operation for a certain period of time, the image capture device 100 enters a power saving mode (T711), at which time the power to the image capture sensor 102 is turned off and the voltage of the power storage device unit 202 is reduced (7H).

[0157] Furthermore, when the user turns the power lever of the imaging device 100 to OFF (T712), the voltage of the power storage device section 202 is reduced to 0 V (7H).

[0158] 10 is a diagram illustrating a means for notifying a user in this embodiment. The imaging device 100 notifies the user by displaying a GUI on the display unit 103 in response to an instruction from the control unit 1011. Here, the global shutter mode is an example of an operation mode of the imaging device 100 that assumes that power is supplied from the power storage device unit 202 to the imaging sensor 102.

[0159] A display 1001 is an example of a display to the user when the user sets the global shutter mode and it is determined that shooting in the global shutter mode cannot be performed based on the degree of deterioration of the power storage device unit 202. Here, the degree of deterioration of the power storage device unit 202 is calculated from the predicted ESR of the power storage device unit 202 and information from the temperature sensor 105.

[0160] Display 1001 notifies the user that the power storage device unit 202 is deteriorating and that image capture is prohibited in the current operating mode. In addition, guidance to an alternative operating mode is provided, and selecting display 1003 changes to the alternative operating mode. Selecting display 1002 switches to a live view state in the current mode. Display 1001 informs the user that the power storage device unit 202 is deteriorating and that image capture is not possible in the current operating mode. Furthermore, image capture can be smoothly performed using an alternative method. Display 1001 is displayed, for example, in step S529 of FIG. 5A.

[0161] Display 1004 is an example of a display to the user when it is determined that shooting in global shutter mode cannot be performed because the temperature of the power storage device unit 202 is extremely low when the user has set the global shutter mode. Display 1004 notifies the user that the power storage device unit 202 cannot be used because it is too low, so the user can know that shooting in global shutter mode will be possible once the temperature of the imaging device 100 rises. As with display 1001, guidance to an alternative operating mode is also provided, and selecting display 1006 changes to the alternative operating mode. Selecting display 1005 switches to a live view state while maintaining the current mode. Display 1004 is displayed, for example, in step S529 of FIG. 5A.

[0162] Similar to display 1001, display 1007 is an example of a display to the user when it is determined that shooting in global shutter mode cannot be performed due to the degree of deterioration of the power storage device unit 202 when the user sets the camera to global shutter mode. Display 1007 notifies the user that replacement of the power storage device unit 202 is necessary. For example, if the power storage device unit 202 can be replaced by the user themselves, this display can prompt the user to replace the power storage device unit 202. Display 1007 is displayed, for example, in step S529 in FIG. 5A.

[0163] Display 1008, like display 1001 and display 1007, is an example of a display to the user when it is determined that shooting in global shutter mode cannot be performed based on the degree of deterioration of the power storage device unit 202 when the user sets the global shutter mode. Display 1008 notifies the user that an abnormality has occurred in the imaging device 100. For example, a user who sees this display can have the imaging device 100 repaired by bringing it to the manufacturer's service desk. Furthermore, by displaying an error number associated with the deterioration of the power storage device unit 202, the user or a service desk staff member can check the error number and know that there is an abnormality in the power storage device unit 202. Display 1008 is displayed, for example, in step S529 of FIG. 5A.

[0164] Display 1009 is an example of a live view display in a state where it has been determined that shooting in global shutter mode is not possible due to the degree of deterioration of the power storage device unit 202. For example, display 1009 is displayed when the user selects display 1002 from display 1001, or when the user selects display 1005 from display 1004. By overlaying an icon indicating that shooting in global shutter mode is prohibited on the live view, the user can easily know whether or not shooting is currently possible. Furthermore, if this display is displayed due to low temperature, the icon is erased when the temperature rises and it becomes possible for the power storage device unit 202 to supply power to the image sensor 102. This lets the user know that shooting is now possible.

[0165] For example, displays 1001, 1004, 1007, 1008, and 1009 are all displayed when it is determined that shooting in global shutter mode is not possible due to the degree of deterioration of the power storage device unit 202. Furthermore, these displays are only displayed when the user sets the imaging device 100 to global shutter mode. As a result, these displays are not displayed while the user is using the imaging device 100 in another mode, for example, and therefore the user can concentrate more on shooting even if the power storage device unit 202 has deteriorated.

[0166] Display 1010 is an example of a live view display in a state where image capture is not possible until charging of the power storage device unit 202 is complete. By overlaying an icon indicating that image capture must be waited on the live view, the user can easily know whether or not image capture is currently possible. In addition, this icon is erased when charging is complete. This allows the user to know that image capture is now possible. Display 1010 is displayed, for example, in step S518 of FIG. 5B.

[0167] Display 1011 is an example of a setting screen of the imaging device 100. For example, when a user presses a menu button on the imaging device 100, display 1011 is displayed on the display unit 103. Display 1011 displays an item for checking the degree of deterioration of the power storage device unit 202, alongside an item for checking information about the battery 108, for example. When a user operates display 1011 to display the degree of deterioration of the power storage device unit 202, display 1012 or display 1013 is displayed depending on the degree of deterioration of the power storage device unit 202. Display 1012 is displayed when the degree of deterioration of the power storage device unit 202 is within a range that allows use in global shutter mode. Display 1012 displays the degree of deterioration of the power storage device unit 202. Display 1013 is displayed when the degree of deterioration of the power storage device unit 202 is such that it cannot be used in global shutter mode. Display 1013 notifies the user that replacement is necessary, in addition to information about the degree of deterioration of the power storage device unit 202. This display can prompt the user to replace the power storage device unit 202.

[0168] Hereinafter, with reference to FIG. 11, a backup power supply configuration using the power storage device unit 202 in the event of an emergency power shutdown of the imaging device 100 (emergency shutdown) in this embodiment will be described. In FIG. 11, the same components as those in FIG. 2 are assigned the same numbers. In the configuration in FIG. 11, a capacitor 111 is added to the configuration in FIG. 2. The capacitor 111 is provided on the input side of the CPU power supply unit 107. When power is supplied from the battery 108 or the USB power supply unit 110, the input charge is stored in the capacitor 111. The capacitor 111 is, for example, a ceramic capacitor or an aluminum electrolytic capacitor, and has a smaller capacity for storing charge than the power storage device 202. The CPU power supply unit 1071 can continue to supply power for a short period of time using the power stored in this capacitor.

[0169] The imaging device 100 operates using the battery 108 or the USB power supply unit 110 as its main power source. Normally, when the control unit 1011 detects that the user has turned off the main power switch, it issues a command to the power supply control unit 106 to transition to a power-saving mode while preventing malfunction of the imaging device 100 in an ideal sequence. In this power-saving mode, the user can safely remove the battery 108 or the USB power supply unit 110 from the imaging device 100. Furthermore, when the control unit 1011 detects that the user has turned off the main power switch during a shooting operation, the imaging device 100 transitions to the power-saving mode after completing development processing of image data stored in the temporary memory 1014. This makes it possible to prevent data from being lost during shooting. In this way, when the user operates the power switch on the operation unit to instruct the imaging device 100 to power off, the normal power-off process is executed.

[0170] On the other hand, if an emergency main power interruption occurs, particularly if the power supply voltage of the CPU power supply unit 1071 drops significantly, the CPU 101 stops, and the imaging device 100 cannot transition to the power saving mode in an ideal sequence. For example, such an emergency power interruption occurs when a user accidentally removes the battery 108 or the USB power supply unit 110 from the imaging device 100 without turning off the main power switch. This emergency power interruption may cause, for example, a malfunction of the imaging device 100 or a loss of image data stored in the temporary memory 1014.

[0171] As a configuration for preventing malfunction of the imaging device 100 and loss of image data in such an emergency power shutdown, first, a voltage monitoring unit 1101 connected to the output of the battery 108 or USB power supply unit 110 monitors the voltage of the main power supply. When it detects that the voltage of the main power supply has fallen below a predetermined voltage, it assumes that an emergency power shutdown has occurred and notifies the power supply control unit 106 of this.

[0172] Upon receiving notification of an emergency power shutdown, the power supply control unit 106 executes emergency shutdown processing to power off the imaging device 100. The power supply control unit 106 first controls the power supply source selection unit 203 and the power storage device charge / discharge unit 204 to turn off. This reduces power consumption of the imaging device 100, thereby extending the time until the power supply voltage of the CPU power supply unit 1071 drops significantly. In addition, the power supply control unit 106 turns on the backup path switch 1102. When the backup path switch 1102 is turned on, a power supply path from the power storage device unit 202 to the CPU power supply unit 1071 is enabled, enabling power supply from the power storage device unit 202. The power storage device unit 202 then acts as a backup power source, and power is supplied to the CPU power supply unit 1071 from the power storage device unit 202. This makes it possible to transition the imaging device 100 to a power-saving mode in an ideal sequence, even if an emergency power shutdown of the main power supply occurs, using power from the power storage device unit 202.

[0173] One possible countermeasure for emergency power cutoff is to provide a battery cover and an open / close detection switch in the storage section for battery 108, and initiate processing to transition to power-saving mode when it detects that the battery cover has been opened, thereby transitioning to power-saving mode before battery 108 is removed. Another possible method is to incorporate a dedicated backup power supply separate from the main power supply into image capture device 100, and use power from the backup power supply to transition to power-saving mode only in the event of an emergency power cutoff. However, both of these methods require dedicated components, which can hinder the miniaturization of image capture device 100 and increase costs.

[0174] In contrast, in this embodiment, the power storage device unit 202, which is used to power the image sensor 102, is used to back up the CPU power supply unit 1071 in the event of an emergency power cutoff. Therefore, there is no need to provide a battery cover or a dedicated backup power supply, and there is little impact on miniaturization of the image capture device 100 or on increased costs.

[0175] Hereinafter, the operation of the image capture device 100 of this embodiment at the time of emergency power-off will be described with reference to the timing chart of FIG.

[0176] At time T1201, when the main power switch of the imaging device 100 is turned on by a user operation, the power supply unit 107 is turned on and the imaging device 100 is ready to capture an image. At this time, the power storage device unit 202 is charged by the power storage device charge / discharge unit 204 to a voltage that enables power to be supplied to the imaging sensor 102. The voltage (12E) of the power storage device unit 202 rises to, for example, 4.5V.

[0177] In this state, if an emergency power cut occurs, for example, when the user accidentally removes the battery 108 or the USB power supply unit 110 from the imaging device 100, the loss of the main power source will cause the voltage (12C) of the CPU power supply unit 1071 to begin to drop rapidly. At this time, if the battery 108 is a two-cell lithium-ion battery, for example, the voltage will drop rapidly from approximately 7.2V.

[0178] When the voltage monitoring unit 1101 detects at time T1202 that the voltage has dropped below a predetermined voltage (below a predetermined threshold), it considers that an emergency power shutdown has occurred, and notifies the power control unit 106 by, for example, switching the output (12D) from High to Low, and emergency shutdown processing is initiated. The voltage detected here is, for example, 5.0 V, a voltage level that does not drop during normal camera operation.

[0179] In the emergency shutdown process, the imaging sensor path (12G) is turned off at time T1203. Specifically, the power supply source selection unit 203 and the power storage device charge / discharge unit 204 are turned off. This cuts off the power supply to the imaging sensor 102, allowing the imaging device 100 to reduce power consumption for operations other than the emergency shutdown process. This also reduces consumption of power stored in the power storage device unit 202. In addition, the backup path (12H) is turned on. Specifically, the backup path switch 1102 is turned on, allowing power to be supplied to the CPU power supply unit 1071 from the power storage device unit 202. This causes the voltage (12C) of the CPU power supply unit 1071 to drop more slowly after time T1203. If the battery 108 or USB power supply unit 110 is removed from the imaging device 100 at T1202, the CPU power supply unit 107 supplies power using the power from the capacitor 111. At T1202, power supply from the battery 108 and the USB power supply unit 110 is stopped, and until power supply from the power storage device unit 202 is started at T1203, the CPU power supply unit 1071 supplies power to the power supply control unit 106 using the power of the capacitor 111.

[0180] Up until time T1204, emergency shutdown processing can be performed while the voltage (12C) of the CPU power supply unit 1071 is maintained by the power storage device unit 202. In emergency shutdown processing from time T1203 onwards, the image capture device 100 may be transitioned to the power saving mode in an ideal sequence that is normally performed when the main power switch is turned off. In another case, the image capture device 100 may be transitioned to the power saving mode more quickly in a special sequence that prioritizes shutting down parts of the image capture device 100 that are at a high risk of failure.

[0181] If the power storage device unit 202 is an EDLC with two cells connected in series, its rated voltage is generally about 5.0 V. In other words, if the battery 108 is a two-cell lithium-ion battery with a battery voltage of 5.0 V or higher, turning on the backup path switch 1102 may apply a voltage higher than the rated voltage to the power storage device unit 202, potentially destroying the power storage device unit 202. Therefore, it is desirable to set the voltage detected by the voltage monitoring unit 1101 to be equal to or lower than the rated voltage of the power storage device unit 202. This makes it possible to supply power from the power storage device unit 202 to the CPU power supply unit 1071 in the event of an emergency power cutoff, while preventing a voltage higher than the rated voltage from being applied to the power storage device unit 202.

[0182] The disclosure of this specification includes the following imaging apparatus, its control method, program, and storage medium.

[0183] (Item 1) An imaging device, A load circuit; a power supply unit that supplies power to the load circuit; an electricity storage device unit that supplies power to the load circuit; a first control unit that performs an emergency shutdown process of the imaging device when power from the power supply unit is suddenly cut off; a first power supply path that supplies power from the power storage device unit to the load circuit; a second power supply path that supplies power from the power storage device unit to the first control unit; a second control unit that controls the power supply path so that, when power from the power supply unit is suddenly cut off, the second power supply path is enabled and power for performing the emergency shutdown process is supplied from the power storage device unit to the first control unit; An imaging device comprising:

[0184] (Item 2) 2. The imaging device according to item 1, wherein the load circuit is an imaging sensor.

[0185] (Item 3) 3. The imaging device according to item 1 or 2, wherein the power storage device is an electric double layer capacitor or an all-solid-state battery.

[0186] (Item 4) 4. The imaging device according to any one of items 1 to 3, wherein the power supply unit is a battery.

[0187] (Item 5) 4. The imaging device according to any one of items 1 to 3, wherein the power supply unit is an external power supply unit that supplies power from an external power supply device to the imaging device.

[0188] (Item 6) The imaging device described in any one of items 1 to 5, characterized in that the second control unit disables the first power supply path when power from the power supply unit is suddenly cut off.

[0189] (Item 7) The imaging device described in any one of items 1 to 6, characterized in that the second control unit determines that power from the power supply unit has been urgently cut off when the voltage supplied from the power supply unit falls below a predetermined threshold.

[0190] (Item 8) 8. The imaging device according to item 7, wherein the threshold is set to a rated voltage or less of the power storage device unit.

[0191] (Item 9) 9. The imaging device according to any one of items 1 to 8, wherein the power storage device is charged with power from the power supply.

[0192] (Item 10) The imaging device described in any one of items 1 to 9, characterized in that the case where power from the power supply unit is urgently cut off is when the power supply unit is removed from the imaging device without operating the power switch of the imaging device.

[0193] (Item 11) 11. The imaging device according to any one of items 1 to 10, wherein the emergency shutdown process is a process for safely shutting down the imaging device without causing any malfunction.

[0194] (Item 12) A method for controlling an imaging device including: a load circuit; a power supply unit that supplies power to the load circuit; a power storage device unit that supplies power to the load circuit; a control unit that performs emergency shutdown processing of the imaging device when power from the power supply unit is suddenly cut off; a first power supply path that supplies power from the power storage device unit to the load circuit; and a second power supply path that supplies power from the power storage device unit to the control unit, A control method for an imaging device, comprising a control step of controlling the power supply path so that, when power from the power supply unit is suddenly cut off, the second power supply path is enabled and power for performing the emergency shutdown process is supplied from the power storage device unit to the control unit.

[0195] (Item 13) Item 13. A program for causing a computer to execute the control method according to Item 12.

[0196] (Item 14) A computer-readable storage medium storing a program for causing a computer to execute the control method described in item 12.

[0197] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more of the functions.

[0198] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0199] 100: imaging device, 101: CPU, 102: imaging sensor, 103: display unit, 104: recording unit, 105: temperature sensor, 106: power supply control unit, 107: power supply unit, 108: battery, 109: battery monitoring unit, 110: USB power supply unit, 1011: control unit, 1012: imaging drive control unit, 1013: image compression unit, 1014: temporary memory, 1015: image correction unit, 1016: display image conversion unit, 1071: CPU power supply unit, 1072: imaging power supply unit

Claims

1. An imaging device, A load circuit; a power supply unit that supplies power to the load circuit; an electricity storage device unit that supplies power to the load circuit; a first control unit that performs an emergency shutdown process of the imaging device when power from the power supply unit is suddenly cut off; a first power supply path that supplies power from the power storage device unit to the load circuit; a second power supply path that supplies power from the power storage device unit to the first control unit; a second control unit that controls the power supply path so that, when power from the power supply unit is suddenly cut off, the second power supply path is enabled and power for performing the emergency shutdown process is supplied from the power storage device unit to the first control unit; An imaging device comprising:

2. 2. The imaging device according to claim 1, wherein the load circuit is an imaging sensor.

3. 2. The imaging device according to claim 1, wherein the power storage device is an electric double layer capacitor or an all-solid-state battery.

4. 2. The imaging device according to claim 1, wherein the power supply unit is a battery.

5. 2. The imaging device according to claim 1, wherein the power supply unit is an external power supply unit that supplies power from an external power supply device to the imaging device.

6. 2. The imaging device according to claim 1, wherein the second control unit disables the first power supply path when power from the power supply unit is suddenly cut off.

7. 2. The imaging device according to claim 1, wherein the second control unit determines that power from the power supply unit has been urgently shut off when the voltage supplied from the power supply unit falls below a predetermined threshold.

8. 8. The imaging device according to claim 7, wherein the predetermined threshold is set to a rated voltage or less of the power storage device unit.

9. 2. The imaging device according to claim 1, wherein the power storage device is charged with power from the power supply.

10. 2. The imaging device according to claim 1, wherein the case where power from the power supply unit is cut off in an emergency is when the power supply unit is removed from the imaging device without operating a power switch of the imaging device.

11. 2. The imaging device according to claim 1, wherein the emergency shutdown process is a process for safely shutting down the imaging device without causing any malfunction.

12. A method for controlling an imaging device including a load circuit, a power supply unit that supplies power to the load circuit, a power storage device unit that supplies power to the load circuit, a control unit that performs emergency shutdown processing of the imaging device when power from the power supply unit is suddenly cut off, a first power supply path that supplies power from the power storage device unit to the load circuit, and a second power supply path that supplies power from the power storage device unit to the control unit, A control method for an imaging device, comprising a control step of controlling the power supply path so that, when power from the power supply unit is suddenly cut off, the second power supply path is enabled and power for performing the emergency shutdown process is supplied from the storage device unit to the control unit.

13. A program for causing a computer to execute the control method according to claim 12.

14. A computer-readable storage medium storing a program for causing a computer to execute the control method according to claim 12.

Images