Image capturing apparatus, control method therefor, and storage medium

Abstract

To provide an imaging apparatus capable of reducing a maximum current during operation while suppressing an increase in cost and an increase in size of the apparatus.SOLUTION: The imaging apparatus includes an imaging sensor, a reading part for reading image data from the imaging sensor, a processing part for processing the image data read by the reading part, a memory to be accessed by the processing part for processing the image data, and a control part for restricting access to the memory of the processing part during the reading period of the image data by the reading part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a power control technique in an imaging device. [Background technology]

[0002] An imaging device has been proposed that incorporates an image sensor capable of simultaneously reading out multiple pixel data, enabling shooting with reduced rolling distortion without using a mechanical shutter. However, the faster the amount of pixel data read, the higher the maximum current required by the image sensor.

[0003] Furthermore, in order to achieve higher pixel counts and higher image quality in imaging devices, faster image processing engines are also required. It has also been proposed to achieve faster image processing by using multiple image processing engines. The maximum value of the current required by an imaging device increases as the processing speed of the image processing engine increases or as a result of using multiple image processing engines.

[0004] If the maximum current increases, the current supplied from the battery of the imaging device may exceed the allowable value, causing the battery voltage to drop and leading to a system shutdown. Also, when the maximum current increases, the voltage drop due to the internal resistance of the battery and wiring resistance increases, causing the voltage to fall below the minimum driving voltage of the imaging device, which may also lead to a system shutdown.

[0005] To prevent this, it is possible to stop the operation before the battery voltage drops below a certain value, but in this case the battery capacity cannot be fully used, and the operating time of the imaging device is significantly reduced.

[0006] Patent Document 1 discloses an imaging device that uses a power storage device as a method for reducing the maximum current. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2024-22343 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the conventional technology disclosed in Patent Document 1 requires the addition of new components, which may result in increased costs and an increased size of the housing.

[0009] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide an imaging device that can reduce the maximum current during operation while suppressing increases in cost and size of the device. [Means for solving the problem]

[0010] The imaging device according to the present invention is characterized by comprising an imaging sensor, a reading means for reading image data from the imaging sensor, a processing means for processing the image data read by the reading means, a memory accessed by the processing means for processing the image data, and a control means for restricting access of the processing means to the memory during the period when the image data is being read by the reading means. [Effects of the Invention]

[0011] According to the present invention, it is possible to reduce the maximum current during operation while suppressing increases in cost and size of the device. [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. 4 is a diagram showing an example of a time chart in an electronic shutter mode of the imaging apparatus. [Figure 3] FIG. 4 is a diagram showing the current drawn from the battery of the imaging device. [Figure 4]4 is a flowchart showing the operation of the front control unit. [Figure 5] 5A and 5B are diagrams showing examples of determinations made by a battery determination unit with respect to the state of a battery; 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] FIG. 1 is a block diagram showing the configuration of an image capturing apparatus 100 according to an embodiment of the present invention.

[0015] 1, the image sensor 101 is a CMOS image sensor, and is configured with a light receiving element and an amplifier that amplifies the electrical signal arranged for each pixel. In this embodiment, the image sensor 101 is configured as a stacked image sensor, and a wiring layer for reading out pixel information is arranged on the back surface of the pixel, making it possible to shorten the readout time. In this embodiment, a rolling shutter image sensor is used, but a global shutter image sensor that can read out all pixels simultaneously may also be used.

[0016] The imaging sensor 101 receives light from a subject at each pixel, photoelectrically converts the light, and converts it into digital data using an A / D converter within the imaging sensor 101. The front engine 102 is an image processing circuit configured as a single semiconductor integrated circuit chip (IC chip). The front engine 102 includes at least one CPU and at least one circuit. The front engine 102 is a video engine that reads image data and other data from the imaging sensor 101, performs the necessary processing, and outputs the data to the back engine 104. The front engine 102 is configured with a front control unit 1021, an imaging readout unit 1022, a display image development unit 1023, and a transmission unit 1024.

[0017] The front control unit 1021 controls the operation of the image sensor 101, the display unit 107, the mechanical shutter 108, the power supply control unit 111, and the like, which will be described later.

[0018] The imaging readout unit 1022 reads image data (image signals) obtained from each pixel of the imaging sensor 101 from the imaging sensor 101 and writes the image data to the readout memory 103. The imaging readout unit 1022 also reads image data to be displayed as a live view from the readout memory 103 and sends it to the display image development unit 1023. As will be described later, when capturing moving images or still images, the imaging readout unit 1022 reads image data stored in the readout memory 103 and sends it to the back engine 104 via the transmission unit 1024. The readout memory 103 is part of the working memory, is configured from an SDRAM (Random Access Memory) or the like, and is used as a buffer memory.

[0019] In a shooting standby state in which a through image (live view image) is displayed, the display image development unit 1023 performs thinning processing and image correction processing for display on the image data read out from the readout memory 103. The image data converted into display data by the display image development unit 1023 is displayed on the display unit 107, which will be described later. The transmission unit 1024 transmits the image data sent from the imaging and reading unit 1022 to the back engine 104.

[0020] The back engine 104 is an image processing circuit configured as a single semiconductor integrated circuit (IC) chip. The back engine 104 includes at least one CPU and at least one circuit. The back engine 104 receives image data output from the front engine 102, performs necessary processing, and then outputs the data to the recording unit 200. The back engine 104 is an image engine that performs noise removal processing, compression processing, recording format conversion processing, etc. on the read image data, and is configured with a back control unit 1041, an image correction unit 1042, an image compression unit 1043, and a receiving unit 1044. The back control unit 1041 communicates with the front control unit 1021 and controls the recording unit 200, which will be described later, etc.

[0021] Image data sent from the front engine 102 is received by the receiving unit 1044 and temporarily stored in the development memory 105. The image correction unit 1042 performs noise removal and correction processing on the image data output from the front engine 102 and stored in the development memory 105, and stores the corrected image data in the development memory 105. The image compression unit 1043 reads the image data corrected by the image correction unit 1042 from the development memory 105 and performs compression processing. JPEG compression processing is performed when recording still images, and H.264 compression processing is performed when recording moving images. The image correction unit 1042 and image compression unit 1043 temporarily store data in the development memory 105 when performing processing. The development memory 105 is part of the working memory, is composed of SDRAM (Random Access Memory) or the like, and is used as a buffer memory.

[0022] The operation unit 106 is used to receive instructions from the user and sends signals to the front control unit 1021. The operation unit 106 includes, for example, operation members such as a power button used by the user to instruct ON / OFF of the power supply to the imaging device 100, a release switch used to instruct shooting, and a zoom lever used to instruct zooming. The operation unit 106 also includes a playback button used to instruct playback of image data, a mode dial used to specify the startup mode of the imaging device 100, and a touch panel disposed on the display unit 107, which will be described later.

[0023] The release switch includes a switch SW1 and a switch SW2. When the release switch is pressed halfway, the switch SW1 is turned on. This allows the front control unit 1021 to receive instructions for preparations for shooting, such as AF (autofocus) processing, AE (auto exposure) processing, AWB (auto white balance) processing, and EF (pre-flash) processing. When the release switch is pressed fully, the switch SW2 is turned on. This allows the front control unit 1021 to receive instructions for shooting.

[0024] The display unit 107 displays live view images during shooting, captured image data, and text for interactive operation. The display unit 107 does not necessarily have to be built into the imaging device 100. The imaging device 100 only needs to be able to connect to an external display unit 107 and have a display control function for controlling the display on the display unit 107.

[0025] The mechanical shutter 108 controls the amount of light that enters the image sensor 101. In the electronic shutter mode, the mechanical shutter 108 is kept open. Only in the mechanical shutter mode does the mechanical shutter 108 operate under the control of the front control unit 1021, and controls the exposure time.

[0026] The data compressed by the image compression unit 1043 is output to the recording unit 200. The recording unit 200 records the image data of the still image or moving image output from the image compression unit 1043 onto a recording medium.

[0027] The recording unit 200 records image data on removable external media such as an SD card, a CF card, or an external SSD device, but may also be configured to record image data in built-in memory.

[0028] Battery 300 corresponds to a power supply source for image capture device 100 and is, for example, a removable lithium-ion battery. A DC coupler can be inserted into the attachment portion of battery 300 instead of the lithium-ion battery. A DC coupler is a power adapter that supplies the necessary voltage to image capture device 100 from a commercial power source via an AC / DC conversion adapter.

[0029] The battery monitoring unit 109 monitors the voltage, remaining capacity, discharge current, and temperature state of the battery 300, and transmits the information to the front control unit 1021. The battery monitoring unit 109 can also calculate the internal resistance of the battery 300 from the discharge current and voltage drop of the battery 300. It can also calculate the resistance value including the contact and wiring when the battery 300 is inserted into the battery 300 attachment unit via an extension grip or the like.

[0030] The battery determination unit 110 determines whether the battery 300 is in a problematic state when the maximum current flows, based on information obtained by the battery monitoring unit 109. The power supply control unit 111 controls the supply of power from the battery 300 to each unit of the imaging device 100. The power supply control unit 111 has a CPU, and controls the power supply in accordance with instructions from the front control unit 1021, as will be described later.

[0031] Representative operating modes of the imaging device 100 include a still image mode (still image shooting mode) and a video mode (video shooting mode). More specifically, the still image mode includes a single-shot mode in which one still image is shot each time the release switch is pressed, and a continuous-shot mode in which still images are continuously captured while the release switch is pressed. The continuous-shot mode also includes a high-speed continuous-shot mode in which a greater number of images are shot per unit time, and a low-speed continuous-shot mode in which a relatively smaller number of images are shot per unit time.

[0032] The imaging device 100 has multiple operating modes. The multiple moving image modes include an 8K recording mode in which moving images are recorded at 8K pixels per screen, a 4K recording mode in which moving images are recorded at 4K pixels per screen, and a full HD recording mode in which moving images are recorded at full HD pixels per screen. The user can also set the frame rate of moving images recorded in the imaging device 100. The operating mode of the imaging device 100 may be changed in response to a user operation, or the front control unit 1021 and the back control unit 1041 may automatically change the operating mode to the optimal mode for the user.

[0033] When a user issues a shooting instruction, such as by pressing the release switch on the operation unit 106, image data is read from the image sensor 101, which has been driven and controlled for actual shooting in accordance with instructions from the front control unit 1021. The image data is written to the read memory 103, undergoes some image processing and thinning processing, and is then sent to the development processing CPU 104. The sent image data undergoes image correction in an image correction unit 1042 implemented by the development CPU 104, is compressed into JPEG or the like in an image compression unit 1043, and is recorded in the recording unit 200.

[0034] When the user presses the video recording button on the operation unit 106, a plurality of frames of video data are successively read out from the imaging sensor 101, which has been driven and controlled for video in accordance with instructions from the front control unit 1021.

[0035] The imaging readout unit 1022 temporarily stores the image data read out from the imaging sensor 101 in the readout memory 103, and then reads the image data from the readout memory 103 and sends it to the back engine 104 via the transmission unit 1024. The image data sent to the back engine 104 is written into the development memory 105 by the reception unit 1044, then read out and corrected by the image correction unit 1042, and further compressed by the image compression unit 1043 before being recorded as a moving image in the recording unit 200.

[0036] In FIG. 1, the thick lines represent the image data path, and the thin lines represent the control signal path. The image data path must transmit high-resolution image data at high speed in order to enable high-speed continuous still image capture and high-frame-rate recording. In particular, when handling large amounts of data at high speed, such as in high-speed continuous still image capture mode, the image sensor 101, front engine 102, and back engine 104 must process the data within a limited time. This results in instantaneous consumption of large amounts of power. As a result, the maximum value of the current flowing from the battery 300 (hereinafter referred to as the "maximum current") increases.

[0037] An example of an operational time chart in the still image mode of the imaging device 100 according to this embodiment will be described below with reference to FIG. 2. FIG. 2 illustrates processing performed when the imaging device 100 is powered on and, in a shooting standby state, receives an instruction to shoot a still image while a live view image is being displayed on the display unit 107. In the shooting standby state, the front control unit 1021 controls the power control unit 111 to limit the power supply to the back engine 104. In this state, the back control unit 1041 can communicate with the front control unit 1021, but the image correction unit 1042 and the image compression unit 1043 cannot perform normal processing. This reduces the power consumption of the back engine 104. Then, as described below, when the switch SW1 is operated, the power control unit 111 is controlled to release the limit on the power supply to the back engine 104. In the following description, the "power saving state" refers to the state in which the power supply to the back engine 104 is limited, as described above. Furthermore, the "standby state" indicates a state in which the restriction on the power supply to back engine 104 is lifted and each part of back engine 104 is operable, but no processing is being executed. In Fig. 2, the horizontal axis represents time, and the vertical axis will be explained sequentially from top to bottom as follows. 10A shows the operation of the switch SW1 in the operation unit 106. (B) shows the operation of switch SW2 on operation unit 106. The release switch is a two-stage switch, and when the user presses switch SW2 to the second stage, single shot shooting is performed. When switch SW2 is pressed and held down, continuous shot shooting is performed. (C) shows the driving mode of the image sensor 101. There are a live view operation state and a still image accumulation and readout operation state. (D) shows the driving mode of the imaging readout unit 1022. There are a live view operation readout state in which image data for live view is read out from the imaging sensor 101, and a still image readout state in which image data for recording is read out from the imaging sensor 101. (E) shows the driving state of the image correction unit 1042. There are an image correction execution state and a standby state. (F) shows the operating state of the image compression unit 1043. There are an image compression execution state and a standby state.

[0038] The processing loads of the processes (D), (E), and (F) vary depending on the operation, settings, and data volume. Therefore, although the image data acquired in each process is processed in chronological order, the timing at which the processes end differs. Furthermore, until each process is completed, the readout memory 103 and the development memory 105 must hold image data corrected by the image correction unit 1042 and subsequently compressed by the image compression unit 1043, as well as image data compressed by the image compression unit 1043 and subsequently recorded by the recording unit 200. Therefore, if a series of continuous shooting processes is completed and the still image data is not sequentially recorded by the recording unit 200, the readout memory 103 and the development memory 105 will run out of space, making it impossible to read the next image data from the image sensor 101. If image data for recording cannot be read from the image sensor 101, continuous shooting cannot continue. As a result, the time during which continuous shooting can be continued is shortened.

[0039] (G) shows an interrupt control from the front control unit 1021 to the back control unit 1041 to request access restriction to the development memory 105.

[0040] A series of communications (SPI, I2C, PCIE, etc.) between the front control unit 1021 and the back control unit 1041 can also include interrupt control communications requesting access restrictions to the developing memory 105. Here, when interrupt processing becomes necessary, in order to promptly notify the back engine 104, an interrupt notification is made using a dedicated signal for an interrupt requesting access restrictions to the developing memory 105. This is to shorten the time for which access restrictions to the developing memory 105, which will be described later, and can prevent the duration of continuous shooting from becoming shorter.

[0041] (H) shows a state in which the back control unit 1041 restricts the image correction unit 1042 and the image compression unit 1043 from accessing the development memory 105 while the front engine 102 is reading image data from the imaging sensor 101.

[0042] 2, the back control unit 1041, triggered by a control instruction for interrupt control (G), restricts access of the image correction unit 1042 and the image compression unit 1043 to the development memory 105. Furthermore, if the maximum value of the current during the still image readout period of the imaging and reading unit 1022 does not increase, it is also possible to restrict access of only one of the image correction unit 1042 and the image compression unit 1043 to the development memory 105. It is also possible to restrict access to the recording unit 200.

[0043] When restricting access to the developing memory 105, access may be completely blocked, or the speed may be restricted by reducing the number of data lanes or communication rate, etc. However, if the developing memory 105 also shares data unrelated to the image path, such as program control, access to the developing memory 105 for data other than the image path shall not be restricted.

[0044] Next, the operation at each timing will be described.

[0045] When the user presses the switch SW1, the image correction unit 1042 and the image compression unit 1043 transition from the power saving state to the standby state (T201).

[0046] When the user presses the switch SW2, the image sensor 101 starts light accumulation (T202).

[0047] The front control unit 1021 sends an interrupt notification to the back control unit 1041 in preparation for the read operation from the image sensor 101 to the front engine 102. The back control unit 1041 restricts the access of the image correction unit 1042 and the image compression unit 1043 to the development memory 105. At this time, the image correction unit 1042 and the image compression unit 1043 are not yet operating, so there is no effect on the operation of the imaging device 100 (T203).

[0048] When accumulation is complete, signal readout from the image sensor 101 to the image capture readout unit 1022 begins (T204). The power consumption of the image sensor 101 and front engine 102 is at its maximum during the period until readout of one frame of image data is completed (T205). The readout period differs depending on the mode. The shorter the readout period relative to the amount of image data to be readout, the greater the instantaneous power consumed by the image sensor 101 and front engine 102. In this embodiment, this readout period is approximately 5 ms when using the electronic shutter for still images.

[0049] When the imaging and reading unit 1022 has completed reading out the image data of one screen of a still image and has completed storing the image data of one screen in the developing memory 105, the front control unit 1021 cancels the interrupt request to the back control unit 1041. The back control unit 1041 also causes the image correction unit 1042 and the image compression unit 1043 to cancel the access restriction to the developing memory 105 (T206). Then, the imaging and reading unit 1022 starts reading out the image data of the still image from the developing memory 105 and sequentially sends the read image data to the image correction unit 1042 of the back engine 104.

[0050] By restricting access to the development memory 105, the operation of the back engine 104 temporarily slows down, and unprocessed image data accumulates in the development memory 105. As a result, the duration of continuous shooting in continuous shooting mode is shortened. For this reason, it is desirable to keep the restriction periods T203 to T206 as short as possible, such as within 0.5 ms, while ensuring a readout section (T204 to T205). The time intervals T203 to T204 and T205 to T206 are determined based on the transition time from the falling and rising edges of the interrupt signal from the front control unit 1021 to the start and end of the access restriction to the development memory 105.

[0051] Thereafter, the image data is read by the front engine 102 and sent to the back engine 104 , where it is subjected to image correction processing by the image correction unit 1042 , compressed by the image compression unit 1043 , and stored in the recording unit 200 .

[0052] Assume that the user presses switch SW2 again (T207). Here, a case will be described in which the user continues to press switch SW2, thereby executing the continuous shooting mode.

[0053] The front control unit 1021 sends an interrupt notification to the back control unit 1041 in preparation for the read operation from the image sensor 101 to the front engine 102. The back control unit 1041 restricts the access of the image correction unit 1042 and the image compression unit 1043 to the development memory 105. At this time, the image correction unit 1042 and the image compression unit 1043 are not yet operating, so there is no effect on the operation of the imaging device 100 (T208).

[0054] When the accumulation is completed, reading out is started (T209) from the image sensor 101 to the image pickup readout unit 1022. During the period until the reading is completed (T210), the power consumption of the image sensor 101 and the front engine 102 is at its maximum.

[0055] The imaging and reading unit 1022 notifies the front control unit 1021 that reading has finished (T210). The front control unit 1021 cancels the interrupt request to the back control unit 1041. In addition, the back control unit 1041 causes the image correction unit 1042 and the image compression unit 1043 to cancel the access restriction to the development memory 105 (T211).

[0056] Thereafter, the data is read by the front engine 102 and sent to the back engine 104 , where it is subjected to image correction processing by the image correction unit 1042 , compression processing by the image compression unit 1043 , and stored in the recording unit 200 .

[0057] Accumulation of the next shot begins, and the front control unit 1021 sends an interrupt notification to the back control unit 1041 in preparation for the read operation from the image sensor 101 to the front engine 102. The back control unit 1041 restricts access to the development memory 105 from the image correction unit 1042 and the image compression unit 1043 (T212).

[0058] After the accumulation is completed, the image data starts to be read from the image sensor 101 to the image pickup readout unit 1022 (T213).

[0059] At this time, the image correction unit 1042 and image compression unit 1043 are processing the previous frame (screen), resulting in high power consumption by the back engine 104. However, since access restrictions are placed on the development memory 105, processing is temporarily delayed, but the power consumption of the back engine 104 can be reduced. During this time, processing of unprocessed image data stored in the readout memory 103 is delayed. However, if the readout speed of the image sensor 101 is fast and the times T212 to T215 are sufficiently short, the impact of the delay in data processing is small. For example, in the case of continuous shooting at 40 frames per second, the processing of the image correction unit 1042 and image compression unit 1043 will be delayed for 5 ms (the readout time described above) out of 25 ms (1 sec ÷ 40 = 25 ms).

[0060] When the imaging and reading unit 1022 has finished reading, the imaging and reading unit 1022 notifies the front control unit 1021 that reading has finished (T214). The front control unit 1021 cancels the interrupt request to the back control unit 1041. In addition, the back control unit 1041 causes the image correction unit 1042 and the image compression unit 1043 to cancel the access restriction to the development memory 105 (T215).

[0061] When the access restriction to the development memory 105 is lifted, the image correcting unit 1042 and the image compressing unit 1043 resume their operations.

[0062] Furthermore, accumulation of the next shot begins, and the front control unit 1021 sends an interrupt notification to the back control unit 1041 in preparation for the read operation from the image sensor 101 to the front engine 102. The back control unit 1041 restricts access to the development memory 105 from the image correction unit 1042 and the image compression unit 1043 (T216).

[0063] After the accumulation is completed, the image data starts to be read from the image sensor 101 to the image pickup readout unit 1022 (T217).

[0064] Thereafter, the imaging and reading unit 1022 notifies the front control unit 1021 that reading has finished (T218). The front control unit 1021 cancels the interrupt request to the back control unit 1041. In addition, the back control unit 1041 causes the image correction unit 1042 and the image compression unit 1043 to cancel the access restriction to the development memory 105 (T219). When the access restriction to the development memory 105 is released, the operations of the image correction unit 1042 and the image compression unit 1043 resume.

[0065] Thereafter, when the user releases the switches SW2 and SW1 (T220), the continuous shooting sequence ends, and the image compression unit 1043 continues processing until the processing of the last image data in the continuous shooting is completed and recording is completed. Thereafter, the front control unit 1021 controls the power control unit 111 to limit the power supply to the back engine 104, and the camera enters a shooting standby state.

[0066] In this embodiment, the sequence for the electronic shutter mode has been described, but in the mechanical shutter mode (when the mechanical shutter is operating), the drive power of the mechanical shutter 108 also increases. Therefore, when the powers of the image sensor 101, front engine 102, and back engine 104 are combined, the current supplied from the battery 300 increases.

[0067] Even in the mechanical shutter mode, front control unit 1021 may notify back control unit 1041 of an interrupt in accordance with the timing of mechanical shutter drive. As a result, the current supplied from battery 300 can be reduced even when mechanical shutter 108 is in operation.

[0068] Furthermore, in this embodiment, an interrupt from the front control unit 1021 to the back control unit 1041 is performed only in the still image mode, in which a large current instantaneously flows from the battery 300. However, in the moving image mode, access control to the development memory 105 may be similarly performed if the processing of the image correction unit 1042 and the image compression unit 1043 can be completed in time. As a result, the current supplied from the battery 300 can be reduced even during moving image mode operation.

[0069] The amount of current supplied from the battery 300 of the imaging device 100 in this embodiment will be described below with reference to FIG.

[0070] Fig. 3(a) shows a case where there is no restriction on access to the development memory 105 by the image correction unit 1042 and the image compression unit 1043. The horizontal axes in Fig. 3(a-1), (a-2), (a-3), (a-4), and (a-5) indicate time, and the time axis is the same for all of them.

[0071] 3(a-1) is a diagram showing a continuous shooting sequence in the imaging device 100. The vertical axis will be explained in order from the top as follows. 10A shows the operation of the switch SW1 in the operation unit 106. (B) shows the operation of switch SW2 in the operation unit 106. The release switch is a two-stage switch, and when pressed and held down in the continuous shooting mode, continuous shooting is performed. (C) shows the timing of still image readout by the image sensor 101. While the switch SW2 is continuously pressed, readout is carried out at a predetermined still image readout cycle.

[0072] The vertical axis of Figure 3(a-2) represents the amount of current flowing through the image sensor 101 during continuous shooting. In Figure 3(a-2), a large current is consumed in accordance with timing (C) when image data is read from each pixel in the image sensor 101.

[0073] 3(a-3) represents the amount of current flowing through the front engine 102 during continuous shooting. The image pickup readout unit 1022 reads image data from the image sensor 101 at the same time that image data is read out from each pixel in the image sensor 101, so a large current is consumed in accordance with the readout.

[0074] 3(a-4) indicates the amount of current consumed by the back engine 104 during continuous shooting. Current is consumed continuously from the point where the reading of the first image is completed.

[0075] The vertical axis of Fig. 3(a-5) represents the sum of the current amounts in Fig. 3(a-2), Fig. 3(a-3), and Fig. 3(a-4). From the second frame onwards, the current consumptions of each figure overlap, and the current flowing from battery 300 reaches its maximum.

[0076] On the other hand, Fig. 3(b) shows a case where access to the development memory 105 of the image correction unit 1042 and the image compression unit 1043 is restricted. The horizontal axes of Figs. 3(b-1), (b-2), (b-3), (b-4), and (b-5) indicate time, and the time axis is common to all of them.

[0077] 3(b-1) is a diagram showing a continuous shooting sequence in the imaging device 100 of this embodiment. The vertical axis will be explained in order from the top as follows. 10A shows the operation of the switch SW1 in the operation unit 106. (B) shows the operation of switch SW2 in the operation unit 106. The release switch is a two-stage switch, and when pressed and held down in the continuous shooting mode, continuous shooting is performed. (C) shows the timing of still image readout by the image sensor 101. While the switch SW2 is continuously pressed, readout is carried out at a predetermined still image readout cycle.

[0078] FIG. 3(b-1) is assumed to be the same continuous shooting sequence as FIG. 3(a-1).

[0079] The vertical axis in Figure 3(b-2) represents the amount of current flowing through the image sensor 101 during continuous shooting. In Figure 3(b-2), a large current is consumed when image data is read from each pixel in the image sensor 101. The image sensor 101 consumes the same current as in Figure 3(a-2).

[0080] The vertical axis of Fig. 3(b-3) represents the amount of current flowing through the front engine 102 during continuous shooting. The image capture readout unit 1022 reads image data from the image sensor 101 at the same time that image data is read from each pixel in the image sensor 101, so a large current is consumed in conjunction with the readout. The front engine 102 also consumes the same current as in Fig. 3(a-3).

[0081] The vertical axis in Fig. 3(b-4) represents the amount of current consumed by the back engine 104 during continuous shooting. Current is consumed continuously from the timing when the image capture readout unit 1022 finishes reading out the first image data and the first image data is sent from the front engine 102. However, at timing (C) shown in Fig. 3(b-1) when the image sensor 101 reads out image data for recording, access to the development memory 105 by the image correction unit 1042 and image compression unit 1043 is restricted, so current consumption temporarily decreases.

[0082] The vertical axis of Figure 3(b-5) shows the sum of the current amounts in Figures 3(b-2), 3(b-3), and 3(b-4). From the second frame onwards, the current consumptions of each figure overlap, and the current supplied from battery 300 reaches its maximum, but the maximum current is kept lower than in Figure 3(a-5). For example, the current reduction effect is about 500 mA for a two-cell battery.

[0083] Hereinafter, the operation of the front control unit 1021 in this embodiment will be described with reference to FIGS.

[0084] When the imaging device 100 is started, in step S401 (hereinafter, "step" will be omitted), the operation of the front control unit 1021 is started. As described above, when the imaging device 100 is powered on, the front control unit 1021 puts the imaging device 100 into a shooting standby state and performs control so as to display a live view image on the display unit 107.

[0085] In S402, the front control unit 1021 waits until the user presses the switch SW1 or the like to instruct reading of a still image.

[0086] When a command to read a still image is issued, in S403 the battery determination unit 110 receives battery information about the battery 300 from the battery monitoring unit 109. The received information includes the type of battery 300, the voltage of the battery 300, the current drawn from the battery 300, and resistance information derived from voltage changes.

[0087] In S404, the front control unit 1021 determines, based on the battery determination information from the battery determination unit 110, whether to issue an interrupt notification to the back control unit 1041, that is, whether to restrict access to the development memory 105 from the image correction unit 1042 and the image compression unit 1043.

[0088] 2, the back control unit 1041 can limit the access to the development memory 105 from the image correction unit 1042 and the image compression unit 1043, thereby reducing the current drawn from the battery 300. On the other hand, there is a disadvantage that the processing of data accumulated in the readout memory 103 is delayed, shortening the duration of continuous shooting by the imaging device 100.

[0089] Therefore, only when the battery determination unit 110 determines that the state of the battery 300 falls below a predetermined state (when a predetermined condition is satisfied), the front control unit 1021 sends an interrupt notification to the back control unit 1041. The predetermined state is when the current supplied from the battery 300 exceeds the allowable value of the battery 300. If the allowable value is exceeded, the voltage of the battery 300 drops, and the protection function of the battery 300 stops output, which may cause a system shutdown of the imaging device 100.

[0090] Furthermore, if the internal resistance or wiring resistance of the battery 300 is high, and the maximum current is large, there is a concern that the supply voltage may fall below the minimum drive voltage of the imaging device 100, causing a system shutdown.

[0091] As a method for determining the predetermined state, first, a determination is made based on the type of battery 300. For example, when a DC coupler is inserted, unlike the battery 300, the output voltage is constant, so even if it operates at a high power, the allowable current of the DC coupler will not be exceeded. Therefore, when a DC coupler is connected, no interrupt notification is sent from the front control unit 1021 to the back control unit 1041.

[0092] On the other hand, if it is determined that an old model battery 300 with a low allowable current is inserted, the front control unit 1021 issues an interrupt notification to the back control unit 1041 in order to reduce the maximum power consumption.

[0093] When it is determined that the standard battery 300 is inserted, the determination is made based on information obtained from the battery monitoring unit 109. A specific method of determination will be described later with reference to FIG.

[0094] If it is determined based on the battery information that access to the developing memory 105 is not to be restricted, the front control unit 1021 returns the process to S402 and waits until the next still image is read out.

[0095] When restricting access to the developing memory 105 based on the battery information, in S405 the front control unit 1021 issues an interrupt notification to the back control unit 1041. As a result, access to the developing memory 105 is restricted.

[0096] In S406, the front control unit 1021 waits for the image capturing and reading unit 1022 to finish reading.

[0097] When the image capturing and reading unit 1022 has finished reading, in S407 the front control unit 1021 cancels the interrupt notification to the back control unit 1041. As a result, the restriction on access to the developing memory 105 is lifted.

[0098] FIG. 5 is a diagram showing an example of the determination made by the battery determination unit 110 with respect to the state of the battery 300 in this embodiment.

[0099] 5A shows a table for the determination in the electronic shutter mode by the battery determination unit 110. Based on this table, the battery determination unit 110 determines whether or not the front control unit 1021 issues an interrupt notification.

[0100] The lower the open-circuit voltage of the battery 300, the larger the maximum current becomes relative to the maximum power required by the image capture device 100, increasing the risk of exceeding the allowable current of the battery 300. Furthermore, if the resistance value of the battery 300 is high, when a large current flows, the voltage supplied to the system of the image capture device 100 becomes lower than a predetermined voltage value, and the voltage falling below the minimum drive voltage of the image capture device 100 also increases the risk of a system failure.

[0101] Therefore, the battery determination unit 110 makes a determination based on the open circuit voltage and resistance value acquired by the battery monitoring unit 109 and the table of FIG. 5(a).

[0102] The horizontal axis represents the open circuit voltage of the battery 300, and the vertical axis represents the resistance value of the battery 300. Only when the diagonally shaded area is reached, the battery determination unit 110 sends an interrupt notification from the front control unit 1021 to the back control unit 1041 and restricts access to the development memory 105. Conversely, in other states where the battery 300 has a margin of error, the front control unit 1021 does not send an interrupt notification to the back control unit 1041 and does not restrict access to the development memory 105.

[0103] The voltage of the battery 300 may be determined from the remaining battery capacity, and the resistance value of the battery 300 may be determined from the temperature of the battery 300 or the presence or absence of a battery grip. If the remaining battery capacity is low (the remaining capacity is below a predetermined amount), the battery temperature is lower than a predetermined temperature, or a battery grip is attached, the risk of a system crash of the imaging device 100 increases, so the front control unit 1021 sends an interrupt notification to the back control unit 1041 and restricts access to the development memory 105.

[0104] As described above, the battery determination unit 110 determines whether to restrict access to the developing memory 105 depending on the state of the battery 300. This makes it possible to suppress the disadvantage of restricting access to the developing memory 105, which is a reduction in the continuous shooting time.

[0105] As shown in Figure 5(b), in mechanical shutter mode, a different table from that shown in Figure 5(a) is used. Alternatively, a different table may be used depending on the state of the image capture device 100, such as the connected accessories or whether or not the device is in a wireless connection state. By determining whether or not to restrict access to the development memory 105 depending on the mode and state of the image capture device 100, it is possible to mitigate the disadvantage of restricting access to the development memory 105 reducing the duration of continuous shooting.

[0106] In the embodiment, the configuration in which the front engine 102 and the back engine 104 are separate has been described, but these functions may be configured as a single semiconductor integrated circuit. Also, this embodiment can be applied to a configuration consisting of three or more image processing circuits.

[0107] As described above, according to this embodiment, it is possible to reduce the instantaneous current flowing into the battery 300 without adding any components or performing any complicated exclusion processing. Furthermore, by restricting access to the development memory 105 in accordance with the state of the battery 300, it is possible to reduce the impact on the duration of continuous shooting by the imaging device 100.

[0108] (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.

[0109] The disclosure of this specification includes the following imaging apparatus, its control method, program, and storage medium.

[0110] (Item 1) an imaging sensor; a readout means for reading out image data from the image sensor; a processing means for processing the image data read by the reading means; a memory accessed by said processing means for processing said image data; a control means for restricting access to the memory by the processing means during a period when the image data is being read by the reading means; An imaging device comprising:

[0111] (Item 2) Item 1. The imaging device according to item 1, characterized in that, when the state of the battery supplying power satisfies a predetermined condition, the control means restricts access to the memory of the processing means during the period when the reading means is reading image data.

[0112] (Item 3) 3. The imaging device according to item 2, further comprising a monitoring unit for monitoring the state of the battery.

[0113] (Item 4) 4. The imaging device according to item 3, further comprising a determination unit that determines whether the state of the battery satisfies the predetermined condition based on information about the state of the battery from the monitoring unit.

[0114] (Item 5) The imaging device described in any one of items 2 to 4, wherein the predetermined condition is at least one of the following: the remaining charge of the battery is less than a predetermined amount; the output voltage of the battery is lower than a predetermined voltage value; the resistance value of the battery is higher than a predetermined resistance value; and the temperature of the battery is lower than a predetermined temperature.

[0115] (Item 6) a first image processing circuit having the readout means and the control means and configured as a single semiconductor integrated circuit chip; a second image processing circuit that has the processing means and is configured as a single semiconductor integrated circuit chip different from the first image processing circuit, the readout means sends the image data read out from the image sensor to the second image processing circuit; the processing means processes the image data sent from the first image processing circuit, 6. The imaging device according to any one of items 1 to 5, wherein the memory is a memory for the second image processing circuit.

[0116] (Item 7) a second memory for the first image processing circuit; the second image processing circuit further comprises a second control means; the reading means stores the image data read from the image sensor in the second memory, and then reads the image data from the second memory and sends it to the second image processing circuit; the control means notifies the second control means of a request for restricting access to the memory before starting to read out image data of one screen from the image sensor, and notifies the second control means of lifting the access restriction when storage of image data of one screen in the second memory is completed; The imaging device described in item 6, characterized in that the second control means controls to restrict the access in response to a notification of a request for restricting the access, and controls to lift the access restriction in response to a notification of lifting the access restriction.

[0117] (Item 8) 8. The imaging device according to any one of items 1 to 7, wherein the processing means comprises a correction means for correcting the image data, and a compression means for compressing the image data corrected by the correction means.

[0118] (Item 9) The imaging device according to any one of items 1 to 8, characterized in that the imaging device is capable of taking still images and taking moving images, and the control means, in the case of taking still images, restricts access to the memory by the processing means during a period in which image data is being read by the reading means.

[0119] (Item 10) The imaging device described in any one of items 1 to 9, further comprising a mechanical shutter that controls exposure of the imaging sensor, wherein the control means restricts access of the processing means to the memory while the mechanical shutter is operating.

[0120] (Item 11) 11. The imaging device according to any one of items 1 to 10, further comprising a recording means for recording image data processed by the processing means, wherein the control means further restricts access of the processing means to the recording means during a period in which the image data is being read by the reading means.

[0121] (Item 12) 1. A method for controlling an imaging device comprising an imaging sensor, the method comprising: a reading step of reading image data from the image sensor; a processing step of processing the image data read in the reading step; an access step of accessing a memory for processing the image data in the processing step; a control step of restricting access to the memory in the processing step during a period in which image data is read in the reading step; 10. A method for controlling an imaging device, comprising:

[0122] (Item 13) Item 13. A program for causing a computer to execute each step of the control method described in Item 12.

[0123] (Item 14) A computer-readable storage medium storing a program for causing a computer to execute each step of the control method described in item 12.

[0124] 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]

[0125] 100: imaging device, 101: imaging sensor, 102: CPU for readout processing, 103: readout memory, 104: CPU for development processing, 109: battery monitoring unit, 110: battery determination unit, 1021: front control unit, 1022: imaging and readout unit, 1023: display image development unit, 1041: back control unit, 1042: image correction unit, 1043: image compression unit, 105: development memory, 300: battery

Claims

1. an imaging sensor; a readout means for reading out image data from the image sensor; a processing means for processing the image data read by the reading means; a memory accessed by said processing means for processing said image data; a control means for restricting access to the memory by the processing means during a period when the image data is being read by the reading means; An imaging device comprising:

2. 2. The imaging device according to claim 1, wherein, when the state of a battery supplying power satisfies a predetermined condition, the control means restricts access to the memory by the processing means while the reading means is reading image data.

3. 3. The imaging device according to claim 2, further comprising a monitoring unit for monitoring the state of the battery.

4. 4. The imaging device according to claim 3, further comprising a determination unit that determines whether the state of the battery satisfies the predetermined condition based on information about the state of the battery from the monitoring unit.

5. 3. The imaging device according to claim 2, wherein the predetermined condition is at least one of the following: the remaining charge of the battery is less than a predetermined amount; the output voltage of the battery is lower than a predetermined voltage value; the resistance value of the battery is higher than a predetermined resistance value; and the temperature of the battery is lower than a predetermined temperature.

6. a first image processing circuit having the readout means and the control means and configured as a single semiconductor integrated circuit chip; a second image processing circuit having the processing means and configured as a single semiconductor integrated circuit chip different from the first image processing circuit, the readout means sends the image data read out from the image sensor to the second image processing circuit; the processing means processes the image data sent from the first image processing circuit, 2. The imaging device according to claim 1, wherein the memory is a memory for the second image processing circuit.

7. a second memory for the first image processing circuit; the second image processing circuit further comprises a second control means; the reading means stores the image data read from the image sensor in the second memory, and then reads the image data from the second memory and sends it to the second image processing circuit; the control means notifies the second control means of a request for restricting access to the memory before starting to read out image data of one screen from the image sensor, and notifies the second control means of lifting the access restriction when storage of image data of one screen in the second memory is completed; The imaging device according to claim 6, characterized in that the second control means controls to restrict the access in response to a notification of a request for restricting the access, and controls to lift the access restriction in response to a notification of lifting the access restriction.

8. 2. The imaging apparatus according to claim 1, wherein said processing means comprises correction means for correcting said image data, and compression means for compressing the image data corrected by said correction means.

9. 2. The imaging device according to claim 1, wherein the imaging device is capable of taking still images and video images, and the control means, in the case of taking still images, restricts access to the memory by the processing means during a period in which image data is being read by the reading means.

10. 2. The imaging device according to claim 1, further comprising a mechanical shutter for controlling exposure of said imaging sensor, wherein said control means restricts access of said processing means to said memory while said mechanical shutter is operating.

11. 2. The imaging device according to claim 1, further comprising a recording means for recording image data processed by the processing means, wherein the control means further restricts access of the processing means to the recording means during a period in which the image data is being read by the reading means.

12. 1. A method for controlling an imaging device comprising an imaging sensor, the method comprising: a reading step of reading image data from the image sensor; a processing step of processing the image data read in the reading step; an access step of accessing a memory for processing the image data in the processing step; a control step of restricting access to the memory in the processing step during a period in which image data is read in the reading step; 10. A method for controlling an imaging device, comprising:

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

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

Images