Imaging apparatus

Abstract

To provide an imaging apparatus capable of suppressing an increase of a temperature during an operation.SOLUTION: An imaging apparatus performs an imaging operation in a plurality of operation modes. The imaging apparatus comprises: an imaging part that generates image data by imaging a subject image via an optical system; a temperature acquisition part that acquires a temperature of the imaging part; and a control part that switches a plurality of operation modes on the basis of the temperature of the imaging part. The plurality of operation modes contain: a first operation mode; and a second operation mode where a power consumption by the imaging part is smaller than that in the first operation mode. The control part changes the operation mode of the imaging apparatus from the first operation mode to the second operation mode when the temperature of the imaging part is elevated to a first temperature during the imaging operation in the first operation mode. The first temperature is less than the temperature that an execution of a predetermined function is limited in the imaging apparatus.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an imaging device that performs imaging operations in a plurality of operation modes. [Background technology]

[0002] Patent Document 1 discloses an imaging device that performs hybrid AF, which switches between imaging signal AF using information corresponding to the contrast state of a captured image and external ranging AF, which measures the distance to a subject using an external ranging system different from the imaging system, according to a focusing degree detected from an imaging signal. The imaging device of Patent Document 1 sets a focusing degree as a condition for switching from external ranging AF to imaging signal AF based on the measured temperature of the external ranging system, etc. Patent Document 1 aims to improve the performance (especially high-speed performance) of hybrid AF by increasing the focusing degree of the switching condition as the temperature increases and by moving the focus lens as close as possible to the in-focus position using external ranging AF before switching to imaging signal AF. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-065193 A [Patent Document 2] JP 2014-063142 A [Patent Document 3] JP 2021-005063 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides an imaging device capable of suppressing an increase in temperature during operation. [Means for solving the problem]

[0005] An imaging device according to the present disclosure performs imaging operations in a plurality of operation modes. The imaging device includes an imaging section that captures an image of a subject via an optical system to generate image data, a temperature acquisition section that acquires the temperature of the imaging section, and a control section that switches between a plurality of operation modes based on the temperature of the imaging section. The plurality of operation modes include a first operation mode and a second operation mode in which power consumption by the imaging section is smaller than that in the first operation mode. When the temperature of the imaging section rises to a first temperature during imaging operations in the first operation mode, the control section changes the operation mode of the imaging device from the first operation mode to the second operation mode. The first temperature is lower than a temperature at which execution of a predetermined function in the imaging device is restricted. Effect of the Invention

[0006] According to the imaging device of the present disclosure, it is possible to suppress an increase in temperature during operation. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a configuration of a digital camera according to a first embodiment of the present disclosure. [Diagram 2] Diagram to explain the AF method in digital cameras [Diagram 3] FIG. 1 is a diagram for explaining an overview of pixel reading in a digital camera; [Figure 4] A diagram for explaining the operation of a digital camera. [Diagram 5] Flowchart for explaining the operation of a digital camera [Figure 6] FIG. 13 is a diagram for explaining a pixel reading method in a digital camera according to a second embodiment; [Figure 7] 11 is a flowchart for explaining the operation of the digital camera according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the inventor(s) provide the attached drawings and the following explanation so that those skilled in the art can fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0009] (Embodiment 1) In the first embodiment, a digital camera that performs autofocus (AF) operations using two different methods will be described as an example of an imaging device according to the present disclosure.

[0010] 1. Configuration The configuration of a digital camera according to the first embodiment will be described with reference to FIGS. 1 to 3. FIG.

[0011] 1 is a diagram showing the configuration of a digital camera 100 according to this embodiment. The digital camera 100 of this embodiment includes an image sensor 115, an image processing engine 120, and a control unit 135. The digital camera 100 also includes, for example, an optical system 110, a lens driving unit 112, a power supply 160, a temperature sensor 165, and an exterior temperature sensor 166. The digital camera 100 also includes a buffer memory 125, a display monitor 130, a card slot 140, a flash memory 145, an operation unit 150, and a communication module 155.

[0012] The optical system 110 includes a focus lens, a zoom lens, an optical image stabilization lens (OIS), an aperture, a shutter, etc. The focus lens is a lens for changing the focus state of a subject image formed on the image sensor 115. The zoom lens is a lens for changing the magnification of a subject image formed by the optical system. The focus lens, etc. are each composed of one or more lenses.

[0013] Lens driving unit 112 drives a focus lens and the like in optical system 110. Lens driving unit 112 includes a motor, and moves the focus lens along the optical axis of optical system 110 under the control of control unit 135. The configuration for driving the focus lens in lens driving unit 112 can be realized by a DC motor, a stepping motor, a servo motor, an ultrasonic motor, or the like.

[0014] The image sensor 115 captures an image of a subject formed via the optical system 110 and generates imaging data. The imaging data constitutes image data indicative of an image captured by the image sensor 115. The image sensor 115 generates new frame image data at a predetermined frame rate (e.g., 30 frames / second). The timing of generating imaging data and the electronic shutter operation in the image sensor 115 are controlled by the control unit 135. The image sensor 115 can be any of various image sensors, such as a CMOS image sensor, a CCD image sensor, or an NMOS image sensor.

[0015] The image sensor 115 performs operations such as capturing still images and capturing through images. The through images are mainly moving images, and are displayed on the display monitor 130 so that the user can determine a composition for capturing a still image. The through images and still images are each an example of a captured image in this embodiment. The image sensor 115 is an example of an imaging section in this embodiment.

[0016] The image sensor 115 of this embodiment includes a plurality of pixels that function as pixels for capturing an image and as sensor pixels for measuring the distance to a subject by an image plane phase difference method. The plurality of pixels are arranged two-dimensionally on the image plane of the image sensor 115 according to the horizontal and vertical directions of the captured image. For example, each pixel includes a photoelectric conversion unit that configures a distance measurement point of the image plane phase difference method and is divided so as to form two types of optical images obtained by pupil division in the optical system 110 on the image plane. The image sensor 115 of this embodiment includes, for example, a signal processing circuit that applies various signal processing to signals output from each pixel. Examples of various signal processing include gain adjustment and OB (Optical Black) clamping for correcting the black level, but are not limited thereto.

[0017] The image processing engine 120 performs various processes on the imaging data output from the image sensor 115 to generate image data, and performs various processes on the image data to generate an image to be displayed on the display monitor 130. The various processes include, but are not limited to, white balance correction, gamma correction, YC conversion processing, electronic zoom processing, compression processing, and expansion processing. The image processing engine 120 may be configured with a hardwired electronic circuit, or may be configured with a microcomputer, processor, etc. using a program.

[0018] The display monitor 130 is an example of a display unit that displays various information. For example, the display monitor 130 displays an image (through image) represented by image data captured by the image sensor 115 and processed by the image processing engine 120. The display monitor 130 also displays a menu screen or the like that allows the user to perform various settings on the digital camera 100. The display monitor 130 can be configured, for example, by a liquid crystal display device or an organic EL device.

[0019] Operation unit 150 is a general term for hard keys such as operation buttons and operation levers provided on the exterior of digital camera 100, and accepts operations by the user. Operation unit 150 includes, for example, a release button for issuing an instruction to start shooting, a mode dial for setting various operation modes such as shooting modes, and a touch panel. When operation unit 150 accepts an operation by the user, it transmits an operation signal corresponding to the user operation to control unit 135.

[0020] The control unit 135 centralizes and controls the overall operation of the digital camera 100. The control unit 135 includes a CPU and the like, and the CPU executes a program (software) to realize a predetermined function. For example, the control unit 135 controls the AF operation of the digital camera 100 by driving the lens driving unit 112.

[0021] Instead of a CPU, the control unit 135 may include a processor configured with a dedicated electronic circuit designed to realize a predetermined function. That is, the control unit 135 can be realized by various processors such as a CPU, an MPU, a GPU, a DSU, an FPGA, and an ASIC. The control unit 135 may be configured with one or more processors. Also, the control unit 135 may be configured with the image processing engine 120 and the like as a single semiconductor chip.

[0022] The buffer memory 125 is a recording medium that functions as a work memory for the image processing engine 120 and the control unit 135. The buffer memory 125 is realized by a dynamic random access memory (DRAM) or the like. The flash memory 145 is a non-volatile recording medium. Although not shown, the control unit 135 may have various types of internal memory, for example, a built-in ROM. The ROM stores various programs executed by the control unit 135. The control unit 135 may also have a built-in RAM that functions as a work area for the CPU.

[0023] The card slot 140 is a means for inserting a removable memory card 142. The card slot 140 is capable of electrically and mechanically connecting the memory card 142. The memory card 142 is an external memory equipped with an internal recording element such as a flash memory. The memory card 142 can store data such as image data generated by the image processing engine 120.

[0024] The communication module 155 is a communication module (circuit) that performs communication in compliance with the communication standard IEEE802.11 or Wi-Fi standard. The digital camera 100 can communicate with other devices via the communication module 155. The digital camera 100 may communicate with other devices directly via the communication module 155, or may communicate via an access point. The communication module 155 may be connectable to a communication network such as the Internet. The communication module 155 may function as an interface for making a wired connection to an external device according to a predetermined standard, and may include a connection circuit that complies with the USB and / or HDMI (registered trademark) standard, for example.

[0025] The power supply 160 supplies power to each element in the digital camera 100. The temperature sensor 165 is realized by, for example, a thermistor, and outputs a voltage according to changes in the surrounding temperature. The temperature sensor 165 in this embodiment is disposed so as to measure the temperature of the image sensor 115. The temperature sensor 165 may include a circuit that converts the output voltage of the thermistor into temperature. The control unit 135 acquires the temperature of the image sensor 115 measured by the temperature sensor 165. The exterior temperature sensor 166 is realized by, for example, a thermistor like the temperature sensor 165, and is provided near the exterior of the digital camera 100.

[0026] 1-1.AF method In the digital camera 100 of this embodiment, the phase difference detection method using phase difference detection (Phase Detection) by the image plane phase difference method and the contrast detection method can be used as the AF method for performing the AF operation. Hereinafter, AF by the phase difference detection method will be referred to as "PDAF", and AF by the contrast detection method will be referred to as "contrast AF". The digital camera 100 of this embodiment has a plurality of operation modes for performing the AF operation by each AF method in the imaging operation of various images.

[0027] In the PDAF method, for example, the image processing engine 120 calculates an evaluation value according to the focus state of the image sensor 115 by image plane phase difference distance measurement based on signals output from pixels of the image sensor 115. Image plane phase difference distance measurement can be performed, for example, by calculating a defocus amount according to the difference between two types of optical images due to pupil division from the output signal for each distance measurement point by each pixel. Publicly known technologies can be appropriately applied to image plane phase difference distance measurement and AF operation by this method (for example, Patent Documents 2 and 3).

[0028] In the contrast AF method, for example, the focus lens is driven so as to maximize the high-frequency components of the spatial frequency in the signal from the pixels included in the image sensor 115. For example, the image processing engine 120 calculates, as an evaluation value, the contrast in the image represented by the image data generated based on the signal.

[0029] Digital camera 100 can set the AF method to be used in AF operation from these various AF methods, depending on various settings such as the shooting mode. During AF operation, the power consumed by digital camera 100 may differ depending on the AF method that is set. The power consumption in each AF method will be described with reference to Figs. 2 and 3.

[0030] Fig. 2 is a diagram for explaining the AF method in the digital camera 100. Fig. 2 shows the power consumption by the image sensor 115 during operation of the PDAF method and the contrast AF method as P1 and P2, respectively, and the power consumption by the camera body such as each part of the digital camera 100 as P3 and P4, respectively, for the PDAF method and the contrast AF method. For example, in a continuous AF (AF-C) mode in which an AF operation is performed to follow the movement of a subject by predicting a moving object in response to a half-press operation of the release button during an image capturing operation such as a through image in still image shooting, the power consumption in Fig. 2 is P2, P1, P4, and P3 in ascending order.

[0031] That is, the power consumption of image sensor 115 in the PDAF method is greater than that in the contrast AF method, and a similar relationship holds true for the entire digital camera 100. For example, the power consumption of image sensor 115 in the PDAF method is 1 W to 2 W, depending on the image sensor used in digital camera 100. The power consumption of image sensor 115 in the contrast AF method is lower than that in the PDAF method, and is, for example, 0.6 W to 1.2 W.

[0032] Such a difference in power consumption due to the AF method may be due to, for example, a difference in pixel readout, which reads out signals from pixels in the image sensor 115. Fig. 3 is a diagram for explaining an overview of pixel readout in the digital camera 100. Fig. 3 shows an example in which a plurality of pixels corresponding to each of the colors R, G, and B are arranged in a Bayer array in the image sensor 115.

[0033] Fig. 3(A) illustrates each pixel 117 to be read out in all-pixel readout in which signals are read out from all pixels of the image sensor 115. Fig. 3(B) illustrates an example in which pixel 118, which is an aggregate of signals from three pixels in the horizontal direction, is read out by pixel mixing in which signals (or data) from multiple pixels of the same color located nearby are added in the image sensor 115. Pixel mixing improves, for example, sensitivity and dynamic range, and reduces the number of pixels to be read out compared to all-pixel readout, thereby reducing power when various signal processing is performed on the signals of each pixel read out by the image sensor 115.

[0034] In the digital camera 100, for example, the PDAF method uses all-pixel readout, while the contrast AF method uses pixel mixing to save power because the performance of the AF operation is not affected by pixel mixing. In addition, in the contrast AF method, in addition to pixel mixing, pixel thinning processing may be performed in the vertical direction of the image sensor 115, in which some pixels are thinned out and signals are read from the remaining pixels. This also reduces the number of pixels to be read out compared to full pixel readout, reducing the power consumption of the image sensor 115. Although FIG. 3B shows an example in which pixel mixing is applied to three pixels in the horizontal direction, the present invention is not limited to this, and pixel mixing processing may be performed, for example, on two pixels in the horizontal direction.

[0035] 2. Operation The operation of digital camera 100 configured as above will now be described.

[0036] 2-1. Overview The digital camera 100 of this embodiment performs, for example, AF operation in AF-C mode while switching between two AF methods with different power consumption during imaging operations such as through-the-lens images. An overview of such operations of the digital camera 100 will be described with reference to FIG.

[0037] Digital camera 100 of this embodiment constantly measures the temperature of image sensor 115 by temperature sensor 165. Fig. 4 is a diagram for explaining the operation of digital camera 100 using a graph illustrating the change over time in image sensor temperature, as the temperature of image sensor 115 measured in this manner. In the graph of Fig. 4, the vertical axis indicates the image sensor temperature, and the horizontal axis indicates the time from the start of AF operation.

[0038] In the example of Fig. 4, first, the AF operation by the PDAF method is continuously performed, and the image sensor temperature rises. For example, as shown in Fig. 2, during continuous AF operation by the AF-C mode in shooting still images, in the PDAF method in which the power consumption of the image sensor 115 is relatively high, the image sensor temperature tends to rise, and the temperature of the main body of the digital camera 100 also tends to rise. For example, if the image sensor temperature continues to rise, there is a concern that the temperature of each part of the digital camera 100 may exceed the temperature assumed as the designed usage environment, affecting operation or causing a breakdown. In addition, for example, if the temperature of the exterior of the digital camera 100 also rises, consideration is also required to prevent low-temperature burns of a user who continues to hold the exterior during shooting.

[0039] For this reason, when the image sensor temperature rises to a certain temperature in digital camera 100, it is conceivable that the execution of certain functions, such as video recording, among the functions that can be executed in the first place may be restricted in order to suppress the temperature rise. Such a thermal shutdown of digital camera 100 may cause inconvenience to the user, such as the inability to use certain functions themselves.

[0040] Therefore, in the digital camera 100 of this embodiment, when the image sensor temperature rises while performing AF operation in the PDAF method, for example, the AF operation is continued by switching to the contrast AF method, which consumes less power than the PDAF method, before the temperature of the thermal shutdown is reached. In the example of Fig. 4, the PDAF method is switched to the contrast AF method at a PDAF limit temperature Tc (for example, 65°C when the thermal shutdown temperature Ts is 70°C) that is less than the thermal shutdown temperature Ts indicating a predetermined temperature (for example, 70°C to 90°C) at which the digital camera 100 is thermally shut down.

[0041] In a contrast AF method that consumes relatively little power, for example, even if AF operations are performed continuously, the rise in image sensor temperature may converge at a temperature lower than the thermal shutdown temperature Ts. In this way, according to the digital camera 100 of this embodiment, the rise in temperature during operation can be suppressed, and a thermal shutdown can be avoided.

[0042] Furthermore, after switching to the contrast AF method, the digital camera 100 of this embodiment switches back to the PDAF method when the image sensor temperature drops to a PDAF restart temperature Tr (for example, 50° C. when the thermal stop temperature Ts is 70° C.) that is set lower than the PDAF limit temperature Tc, as shown in Fig. 4. This allows for relatively high-speed AF operation by distance measurement using the PDAF method to be performed, for example, until the image sensor temperature reaches the PDAF limit temperature Tc.

[0043] 2-2.AF method switching operation The above-described operation of switching the AF method in the digital camera 100 of this embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart for explaining the operation of the digital camera 100.

[0044] The process shown in the flowchart of FIG. 5 is executed by the control unit 135, for example, when the digital camera 100 is turned on and the image sensor 115 is performing an image capturing operation such as a through image in a shooting mode for capturing a still image.

[0045] First, the control unit 135 of the digital camera 100 judges whether or not AF operation by the PDAF method has been started during imaging operation (S1). For example, the digital camera 100 starts AF operation by the set AF method in response to the start of imaging operation. If AF operation by the PDAF method has not been started (NO in S1), such as when the set AF method is the contrast AF method, the control unit 135 repeats the judgment of step S1 at a predetermined cycle, such as a frame cycle.

[0046] When the AF operation using the PDAF method is started (YES in S1), the control unit 135 determines whether or not the image sensor temperature has reached the PDAF limit temperature Tc (S2) based on the measurement result by the temperature sensor 165. For example, the control unit 135 acquires the image sensor temperature periodically measured by the temperature sensor 165, and determines whether the acquired image sensor temperature is equal to or higher than the PDAF limit temperature Tc.

[0047] In the digital camera 100 of this embodiment, the PDAF limit temperature Tc is preset to a temperature lower than the thermal stop temperature Ts. For example, the set values ​​of the temperatures Tc, Ts and the PDAF restart temperature Tr are stored in the flash memory 145 or the like. For each of the temperatures Tc, Ts and Tr, a plurality of set values ​​may be provided according to, for example, the temperature indicated by the measurement result of the exterior temperature sensor 166. For example, when the temperature measured by the exterior temperature sensor 166 is relatively high, a set value of the PDAF limit temperature Tc having a larger difference from the thermal stop temperature Ts (i.e., a lower value) than when the temperature is relatively low may be used. When the image sensor temperature has not reached the PDAF limit temperature Tc (NO in S2), the control unit 135 repeats the determination of step S2, for example, at a predetermined cycle.

[0048] When the image sensor temperature reaches the PDAF limit temperature Tc (YES in S2), the control unit 135 changes the AF method used to execute the AF operation from the PDAF method to the contrast AF method (S3). In the example of Fig. 4, after the AF operation by the PDAF method is started (YES in S1), the image sensor temperature reaches the PDAF limit temperature Tc at time t1 (YES in S2), and the AF method is switched from the PDAF method to the contrast AF method (S3).

[0049] After changing to the contrast AF method (S3), the control unit 135 determines whether the image sensor temperature has dropped to the PDAF resumption temperature Tr (S4). The control unit 135 performs the determination of step S4 depending on whether the image sensor temperature periodically acquired from the temperature sensor 165 is equal to or lower than the PDAF resumption temperature Tr, for example.

[0050] The PDAF restart temperature Tr is preset to a sufficiently low temperature from the viewpoint of lowering the image sensor temperature to a level where the AF operation by the PDAF method can be continuously performed for a predetermined period when the AF operation by the PDAF method is resumed (S5 described later). In the example of Fig. 4, the PDAF restart temperature Tr is set to a temperature equal to or higher than the temperature at which the rise in the image sensor temperature converges when the AF operation by the contrast AF method is continuously performed. If the image sensor temperature has not decreased to the PDAF restart temperature Tr (NO in S4), the control unit 135 repeats the determination of step S4 at a predetermined cycle.

[0051] When the image sensor temperature drops to the PDAF restart temperature Tr (YES in S4), the control unit 135 changes the AF method used to execute the AF operation from the contrast AF method to the PDAF method (S5). In the example of Fig. 4, after changing to the contrast AF method at time t1 (S3), the image sensor temperature drops to the PDAF restart temperature Tr at time t2 (YES in S4), and the method is changed again from the contrast AF method to the PDAF method (S5).

[0052] The control unit 135 repeats the processes from step S2 onwards until the imaging operation in the imaging mode being executed in the digital camera 100 is ended in response to a user operation or the like.

[0053] According to the above operation of digital camera 100, after starting AF operation using the PDAF method (YES in S1), when the image sensor temperature reaches the PDAF limit temperature Tc (YES in S2), the AF method is changed to the contrast AF method (S3). In digital camera 100, power consumption during AF operation is smaller in the contrast AF method than in the PDAF method (see FIG. 2), so it is possible to suppress an increase in temperature during operation. In this way, even if the image sensor temperature rises during imaging operation in which AF operation using the PDAF method is performed, a thermal shutdown can be avoided by switching to the contrast AF method at the PDAF limit temperature Tc, which is lower than the thermal shutdown temperature Ts. This allows, for example, imaging operation involving AF operation to continue.

[0054] Furthermore, in the above operation of digital camera 100, after the AF method is changed to the contrast AF method (S3), if the image sensor temperature drops to the PDAF resumption temperature Tr (YES in S4), the AF method is changed to the PDAF method (S5). In this way, by returning to the PDAF method, which has a relatively fast AF operation, in response to the drop in the image sensor temperature caused by the change to the contrast AF method, it is possible to improve performance such as the tracking ability of the AF operation.

[0055] In the above description, when the image sensor temperature drops to the PDAF resumption temperature Tr (YES in S4), the AF method is changed to the PDAF method (S5). In this case, instead of the process of step S5, the digital camera 100 may display a notification to the user on the display monitor 130 or the like that indicates that the PDAF method is available.

[0056] 3. Summary As described above, the digital camera 100 in this embodiment is an example of an imaging device that performs imaging operation using two types of AF methods as an example of a plurality of operation modes. The digital camera 100 includes the image sensor 115, which is an example of an imaging section, and the control section 135, which is an example of a temperature acquisition section and a control section. The image sensor 115 captures an image of a subject via the optical system 110 to generate image data. The control section 135 acquires the temperature of the image sensor 115. The control section 135 switches between two types of AF methods based on the temperature of the image sensor 115 (S1 to S5). The two types of AF methods include a PDAF method (an example of a first operation mode) and a contrast AF method (an example of a second operation mode) in which the power consumption of the image sensor 115 is smaller than that of the PDAF method. When the image sensor temperature, which is an example of the temperature of the image sensor 115, rises to the PDAF limit temperature Tc (an example of a first temperature) during imaging operation in the PDAF method (YES in S1) (YES in S2), the control section 135 changes the AF method of the digital camera 100 from the PDAF method to the contrast AF method (S3). The PDAF limit temperature Tc is less than a thermal shutdown temperature Ts, which is an example of a temperature at which the execution of a predetermined function in the digital camera 100 is limited.

[0057] According to the digital camera 100 described above, during imaging operation in which AF operation is performed using the PDAF method (YES in S1), if the image sensor temperature rises to the PDAF limit temperature Tc (YES in S2), the AF method is changed from the PDAF method to the contrast AF method (S3). As illustrated in FIG. 2, the power consumption P2 by the image sensor 115 in the contrast AF method is smaller than the power consumption P1 in the PDAF method. In this way, by switching to the contrast AF method, which consumes less power than the PDAF method, it is possible to suppress an increase in temperature during operation of the digital camera 100. Also, by changing the AF method in this way when the risen image sensor temperature reaches the PDAF limit temperature Tc, which is lower than the thermal stop temperature Ts, it is possible to avoid a thermal stop in the digital camera 100, which limits the execution of a predetermined function, such as video shooting, by way of example.

[0058] In this embodiment, after changing the AF method of the digital camera 100 from the PDAF method to the contrast AF method (S3), if the image sensor temperature drops to a PDAF restart temperature Tr (an example of a second temperature) lower than the PDAF limit temperature Tc during imaging operation in the contrast AF method (YES in S4), the control unit 135 changes the AF method of the digital camera 100 from the contrast AF method to the PDAF method (S5). In this way, if the image sensor temperature drops after changing to the contrast method, the AF method used in the AF operation can be returned to the PDAF method before the change. Note that the digital camera 100 does not necessarily have to execute the processes of steps S4 and S5.

[0059] In this embodiment, the PDAF method and the contrast AF method (each one example of a first and second operation mode) are AF methods that have different power consumptions for autofocus (AF) operation in the image sensor 115. The digital camera 100 of this embodiment can avoid a thermal shutdown while continuing the AF operation by switching between such AF methods with different power consumptions.

[0060] In this embodiment, in the PDAF method, which is an example of the first operation mode, the digital camera 100 performs AF operation by a phase difference detection method, and in the contrast AF method, which is an example of the second operation mode, the digital camera 100 performs AF operation by a contrast detection method. For example, in the PDAF method, the speed of AF operation such as tracking a moving subject can be improved by distance measurement using the phase difference detection method. Also, in the contrast AF method, it is possible to perform AF operation with high accuracy while suppressing power consumption by pixel mixing when reading data from pixels on the image sensor 115.

[0061] In this embodiment, the digital camera 100 performs still image capture operations such as shooting still images in the PDAF method and the contrast AF method. For example, when shooting still images, it is considered that by generating image data for live view using pixel mixing regardless of the image quality etc. of the image recorded in the digital camera 100, it is easier to control the temperature during operation by changing the AF method that has different power consumption when reading pixels.

[0062] In this embodiment, the PDAF method and the contrast AF method are AF methods in which the image sensor 115 consumes different amounts of power in reading out signals output from a plurality of pixels included in the image sensor 115. As illustrated in FIG. 3A, in the PDAF method, the image sensor 115 reads out signals from all pixels 117 in the plurality of pixels. As illustrated in FIG. 3B, in the contrast AF method, the image sensor 115 reads out signals by aggregating two or more pixels in the plurality of pixels or thinning out some of the pixels, for example, by reading out pixel 118 in which pixels are mixed. According to the digital camera 100 of this embodiment, the AF method can be changed between the PDAF method and the contrast AF method, which consume different amounts of power in reading out pixels, depending on the image sensor temperature.

[0063] In this embodiment, digital camera 100 includes temperature sensor 165 capable of measuring the temperature of image sensor 115, and control unit 135 acquires the image sensor temperature from temperature sensor 165. This makes it possible to change the AF method, for example, based on the image sensor temperature measured with high accuracy by temperature sensor 165 capable of directly measuring the temperature of image sensor 115.

[0064] (Embodiment 2) A second embodiment of the present disclosure will be described below with reference to Fig. 6 and Fig. 7. In the first embodiment, a digital camera 100 that switches between two AF methods with different power consumptions depending on the image sensor temperature has been described. In the second embodiment, a digital camera that switches between a plurality of pixel readout methods with different power consumptions depending on the image sensor temperature according to the image quality in image capture will be described.

[0065] Hereinafter, the description of the configuration and operation similar to those of the digital camera 100 according to the first embodiment will be omitted as appropriate, and the digital camera according to this embodiment will be described.

[0066] 1. Pixel readout method The digital camera 100 of this embodiment can use three types of pixel readout methods as methods for reading pixels from each pixel of the image sensor 115. Fig. 6 is a diagram for explaining the pixel readout methods in the digital camera 100 of this embodiment. For example, as shown in Fig. 6(A), the pixel readout methods include a pixel thinning method that performs pixel thinning processing also in the horizontal direction of the image sensor 115, in addition to the methods corresponding to all pixel readout and pixel mixing described with reference to Fig. 3 in the first embodiment.

[0067] Fig. 6(A) shows the power consumption by the image sensor 115 during operation in the all pixel readout method, pixel mixing method, and pixel thinning method as P5, P6, and P7, respectively. For example, in a live view in which moving images such as through images are displayed in real time on the display monitor 130, the power consumption in Fig. 6(A) is P5, P6, and P7 in descending order. That is, among the three types of pixel readout methods shown in Fig. 6(A), the power consumption is the highest in the all pixel readout method, the next highest in the pixel mixing method, and the lowest in the pixel thinning method.

[0068] Fig. 6(B) shows an example in which, from a plurality of pixels arranged in the image sensor 115 in the same manner as in Fig. 3, some pixels 116 are thinned out by a pixel thinning method, and the remaining pixels 119 are read out. In such a pixel thinning method, the number of pixels to be read out is smaller than in the all-pixel reading method (see Fig. 3(A)), and power consumption when various signal processing is performed on the signals of each pixel read out in the image sensor 115 is reduced. Also, compared to the pixel mixing method (see Fig. 3(B)), for example, the pixel thinning method that does not perform pixel mixing processing can further reduce power consumption related to pixel readout.

[0069] For example, in live view, the image quality when displaying a captured image such as a through image is highest in the all-pixel readout method, which reads out the largest number of pixels, among the three types of pixel readout methods shown in Fig. 6(A), and is lower in the other pixel readout methods than the all-pixel readout method. The digital camera 100 of this embodiment can be used by switching between various pixel readout methods, for example, by changing the image quality for displaying a captured image in such live view.

[0070] 2. Operation Fig. 7 is a flowchart for explaining the operation of the digital camera 100 of the embodiment 2. The digital camera 100 of the embodiment performs the process shown in the flowchart of Fig. 7 instead of the process of Fig. 5 of the embodiment 1 during the execution of an imaging operation in, for example, a shooting mode for shooting a moving image.

[0071] In the digital camera 100 of this embodiment, the control unit 135 determines whether or not the pixel readout method to be used for live view display is the all-pixel readout method (S11), for example, instead of step S1 in which the AF method to be used for AF operation in the first embodiment is determined. In the digital camera 100 of this embodiment, for example, information indicating the correspondence between the image quality of the live view display and the pixel readout method may be stored in advance in the flash memory 145 or the like. In the digital camera 100, the control unit 135 may, for example, refer to the information and determine the pixel readout method from the image quality set for recording the captured image.

[0072] When the pixel readout method is the all-pixel readout method (YES in S11), the control unit 135 of this embodiment determines whether the image sensor temperature has reached a first temperature (S12), instead of step S2 in which it is determined whether the temperature has risen to the PDAF limit temperature Tc in the first embodiment. The first temperature is set in advance to a temperature lower than the thermal stop temperature Ts, for example, similar to the PDAF limit temperature Tc in the first embodiment.

[0073] When the image sensor temperature reaches the first temperature (YES in S12), the control unit 135 of this embodiment changes the pixel readout method from the all-pixel readout method to a pixel mixing or pixel thinning method (S13), for example, instead of step S3 in which the AF method was changed in embodiment 1. In step S13, the control unit 135 changes the pixel readout method used for live view display to a method with lower power consumption, for example, by lowering the image quality of the live view display compared to before the image sensor temperature reached the first temperature (NO in S12).

[0074] After changing to the pixel mixing method or pixel thinning method (S13), the control unit 135 of this embodiment determines whether the image sensor temperature has dropped to a second temperature lower than the first temperature (S14), instead of step S4 in the first embodiment in which it is determined whether the temperature has dropped to the PDAF resumption temperature Tr. The second temperature is preset to a sufficiently low temperature from the viewpoint of lowering the image sensor temperature to a level that allows live view display by the all-pixel readout method to be continued for a predetermined period even if the live view display by the all-pixel readout method is resumed. The second temperature may be the same as or different from the PDAF resumption temperature Tr in the first embodiment.

[0075] When the image sensor temperature drops to the second temperature (YES in S14), the control unit 135 of this embodiment changes the pixel readout method again from the pixel mixing or pixel thinning method to the all-pixel readout method (S15), instead of step S5 of the first embodiment in which the AF method was changed again. In step S15, the control unit 135 changes the pixel readout method, for example, by returning the image quality of the live view display to an image quality corresponding to the all-pixel readout method.

[0076] According to the above operation of the digital camera 100, for example, by changing the image quality in the live view display, the corresponding pixel readout method can be changed to a method with lower power consumption, thereby suppressing the rise in temperature as in the first embodiment (S11 to S13). For example, in the digital camera 100, when shooting a video in which the live view display is performed with the same image quality as the image to be recorded, it is considered that the temperature during operation can be easily controlled by changing the image quality. Furthermore, if the image sensor temperature drops after such a change to the pixel readout method with lower power consumption (YES in S14), the image quality of the live view display can be improved by returning to the all pixel readout method before the change (S15).

[0077] Although an example has been described above in which the pixel readout method is changed when capturing a moving image, the present invention is not limited to this. The pixel readout method may also be changed by the above-described operation of digital camera 100 when capturing a still image.

[0078] 3. Summary In this embodiment, the all-pixel readout method and the pixel mixing method or pixel thinning method (examples of the first and second operation modes) of the digital camera 100 are pixel readout methods that have different power consumptions for reading signals output from a plurality of pixels included in the image sensor 115. In the all-pixel readout method, the image sensor 115 reads signals from all pixels 117 in the plurality of pixels (see FIG. 3A). In the pixel mixing method or pixel thinning method, the image sensor 115 reads signals by aggregating two or more pixels in the plurality of pixels or thinning out some of the pixels 116 (see FIGS. 3B and 6B). The digital camera 100 of this embodiment can also change the pixel readout method with different power consumptions in accordance with the image sensor temperature, for example by changing the image quality of the live view display, thereby suppressing an increase in temperature during operation.

[0079] (Other embodiments) As described above, the first and second embodiments have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are appropriately made. In addition, it is also possible to combine the components described in the first and second embodiments to create new embodiments.

[0080] In the above-described first and second embodiments, in digital camera 100, control unit 135 acquires the image sensor temperature from temperature sensor 165 arranged to measure the temperature of image sensor 115. In this embodiment, control unit 135 may acquire the image sensor temperature based on the measurement result from a temperature sensor arranged in digital camera 100 at a position different from that of image sensor 115, instead of temperature sensor 165.

[0081] For example, control unit 135 of this embodiment may acquire a temperature measured near the exterior of digital camera 100 from exterior temperature sensor 166 shown in Fig. 1, and calculate the image sensor temperature based on the acquired temperature. For example, in digital camera 100 of this embodiment, information indicating the relationship between the temperature measured by exterior temperature sensor 166 and the image sensor temperature is stored in advance in flash memory 145 or the like, and control unit 135 may calculate the image sensor temperature by referring to the information.

[0082] As described above, digital camera 100 of this embodiment includes exterior temperature sensor 166 as an example of a temperature sensor capable of measuring the temperature of a portion of digital camera 100 other than image sensor 115. Control unit 135, an example of a temperature acquisition unit, calculates the temperature of image sensor 115 based on the measurement result by exterior temperature sensor 166. Based on the image sensor temperature calculated in this manner, the operation mode of digital camera 100, such as the AF method or pixel readout method, can be changed so as to suppress an increase in temperature during operation, as in the first and second embodiments, for example.

[0083] The digital camera 100 described above can also suppress a rise in temperature during operation by changing the operation mode, such as the AF method or pixel readout method, based on the image sensor temperature calculated based on the measurement result of the exterior temperature sensor 166, as in the first and second embodiments. The digital camera may also change the operation mode in accordance with, for example, the temperature near the exterior measured by the exterior temperature sensor 166, not limited to the image sensor temperature, as in the first and second embodiments. For example, the thermal shutdown temperature Ts of the digital camera may be set from the viewpoint of avoiding low-temperature burns of the user caused by continuing to touch the exterior when the temperature near the exterior rises. Such an operation according to the temperature near the exterior can also improve safety while avoiding thermal shutdown.

[0084] In each of the above embodiments, the digital camera 100 is described as having the temperature sensor 165 and the exterior temperature sensor 166. The digital camera of this embodiment may have only one of the temperature sensors 165, 166 used to acquire the image sensor temperature. Also, the digital camera may not have a temperature sensor. For example, the control unit 135 may acquire information indicating the temperature near the exterior from a temperature sensor or the like external to the digital camera via the communication module 155.

[0085] In the above-mentioned embodiment 1, the digital camera 100 performs AF operation by the PDAF method and the contrast AF method, respectively, as examples of the first and second operation modes. In this embodiment, the first and second operation modes are not limited to these, and AF operation using various distance measurement methods or distance information can be applied. For example, instead of the contrast AF method, a DFD method using distance measurement by DFD (Depth from defocus) technology for AF operation, or a TOF (Time of flight) method in which a distance measurement unit is arranged inside or outside the digital camera 100, or a distance measurement method using distance measurement by various active sensing such as a range finder may be applied. The digital camera 100 may perform AF operation by combining these various AF methods.

[0086] In the above embodiment, for example, in the DFD method, power consumption can be reduced more than in the PDAF method by using pixel mixing in the horizontal direction of the image sensor 115, similar to the contrast AF method. Also, in the distance measurement method using active sensing, by using a sensor other than the image sensor 115, pixel reading from the image sensor 115 is not performed, so power consumption can be reduced more than in the PDAF method.

[0087] As described above, in this embodiment, the digital camera 100 performs AF operation in at least one of the contrast detection method, the DFD method, and the distance measurement method using active sensing, which are examples of the second operation mode. This also allows the AF operation to be performed with less power consumption in the second operation mode than in the PDAF method, which is an example of the first operation mode.

[0088] In the above-described first embodiment, after the digital camera 100 changes the AF method from the PDAF method to the contrast AF method (S3), when the image sensor temperature drops to the PDAF restart temperature Tr (YES in S4), the AF method is changed again to the PDAF method (S5). For example, instead of step S4 in which the drop in the image sensor temperature is determined, the digital camera of this embodiment may determine whether or not a predetermined period has elapsed after the change to the contrast AF method (S3), and may change to the PDAF method when the predetermined period has elapsed (S5). Also, each AF method may be intermittently switched at each such predetermined period, or the AF method may be changed. The predetermined period may be set by the number of frames captured in the imaging operation during that period.

[0089] In the above embodiment, after changing to the contrast AF method (S3), the digital camera may change to the PDAF method (S5), for example, when a predetermined number of still images (e.g., 10 images) are recorded during AF operation using the changed AF method. After that, the digital camera of this embodiment may switch between AF methods every time a predetermined number of still images are recorded.

[0090] In the above-described first embodiment, an example was described in which the digital camera 100 changes the AF method from the PDAF method to the contrast AF method when the image sensor temperature rises to the PDAF limit temperature Tc (YES in S2) (S3). The digital camera of this embodiment may, for example, when the image sensor temperature rises to a predetermined temperature, suggest to the user to change to the contrast AF method depending on the shooting scene by displaying on the display monitor 130, etc. For example, the image captured immediately before may be read from the memory card 142, etc., and a change to the contrast AF method may be suggested in a shooting scene in which the subject does not move much, such as a landscape, and the advantages of using the PDAF method, such as high-speed AF operation, are not necessarily expected.

[0091] In the above embodiment, the AF method may be changed to the contrast AF method in response to a user's operation to accept the proposed change to the contrast AF method on the operation unit 150. Also, the digital camera may automatically change the AF method according to the shooting scene without any particular presentation to the user or user operation. The predetermined temperature in this embodiment may be set to a temperature equal to or lower than the PDAF limit temperature Tc, for example.

[0092] In the above-described first embodiment, an example has been described in which the digital camera 100 changes the AF method used in the AF operation when shooting a still image. In this embodiment, the digital camera is not limited to shooting still images, and may change the AF method when shooting moving images, for example, in the same manner as in the first embodiment.

[0093] In each of the above embodiments, the digital camera 100 is described as not being provided with a cooling fan. According to the operation of the digital camera 100 in each of the above embodiments, it is possible to suppress the rise in temperature during operation without providing such a fan, and for example, to avoid thermal shutdown, but the digital camera of this embodiment may further include a cooling fan. In such a digital camera, for example, the rise in temperature during operation can be further suppressed by driving the fan, and the image sensor temperature can be reduced more quickly.

[0094] In the above embodiments, video capture is exemplified as a function whose execution is restricted by thermal shutdown of digital camera 100. In addition to or instead of video capture, the function whose execution is restricted by thermal shutdown may be, for example, image recording by writing image data to memory card 142, output of image data via HDMI connection in communication module 155, and / or power supply via USB connection. In thermal shutdown, the execution of any one or a combination of these functions may be restricted, or the supply of power from power source 160 to each part of the digital camera may be stopped (i.e., the power supply to the digital camera may be cut off).

[0095] In the above embodiment 1, an example has been described in which pixels are thinned out only in the vertical direction of the image sensor 115 in the contrast AF method. In this embodiment, pixels may also be thinned out in the horizontal direction of the image sensor 115 in the contrast AF method.

[0096] In addition, in each of the above embodiments, the digital camera 100 including the optical system 110 and the lens driving unit 112 has been exemplified. The imaging device of the present embodiment does not need to include the optical system 110 and the lens driving unit 112, and may be, for example, an interchangeable lens camera capable of AF operation.

[0097] In addition, in each of the above embodiments, a digital camera has been described as an example of an imaging device, but the imaging device of the present disclosure may be any electronic device (e.g., a video camera, a smartphone, a tablet terminal, etc.) that has an image capturing function in a plurality of operation modes.

[0098] As described above, the embodiments have been described as examples of the technology in the present disclosure, and the accompanying drawings and detailed description have been provided for this purpose.

[0099] Therefore, among the components described in the attached drawings and the detailed description, not only are there components essential for solving the problem, but there may also be components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that such non-essential components are described in the attached drawings or the detailed description should not be interpreted as immediately indicating that such non-essential components are essential.

[0100] Furthermore, since the above-described embodiments are intended to illustrate the technology in the present disclosure, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents.

[0101] Aspects of the present disclosure The following provides examples of aspects of the present disclosure.

[0102] A first aspect of the present disclosure is an imaging device that performs imaging operations in a plurality of operation modes. The imaging device of the first aspect includes an imaging section that captures an image of a subject via an optical system to generate image data, a temperature acquisition section that acquires the temperature of the imaging section, and a control section that switches between a plurality of operation modes based on the temperature of the imaging section. The plurality of operation modes include a first operation mode and a second operation mode in which the power consumption by the imaging section is smaller than that in the first operation mode. When the temperature of the imaging section rises to a first temperature during imaging operations in the first operation mode, the control section changes the operation mode of the imaging device from the first operation mode to the second operation mode. The first temperature is less than a temperature at which execution of a predetermined function in the imaging device is restricted.

[0103] In a second aspect, in the imaging device of the first aspect, the control unit changes the operation mode of the imaging device from the second operation mode to the first operation mode when the temperature of the imaging unit drops to a second temperature lower than the first temperature during imaging operation in the second operation mode after changing the operation mode of the imaging device from a first operation mode to a second operation mode.

[0104] In a third aspect, in the imaging device according to the first or second aspect, the first and second operation modes are operation modes in which power consumption is different for autofocus operation in the imaging section.

[0105] In a fourth aspect, the imaging device of the third aspect performs autofocus operation using a phase difference detection method in a first operating mode, and performs autofocus operation using at least one of a contrast detection method, a DFD (Depth from defocus) method, and an active sensing ranging method in a second operating mode.

[0106] In a fifth aspect, the imaging device according to the third aspect performs an imaging operation of a still image in the first and second operation modes.

[0107] In a sixth aspect, in the imaging device according to any one of the first to fifth aspects, the first and second operation modes are operation modes in which the imaging unit consumes different amounts of power for reading out signals output from a plurality of pixels included in the imaging unit. In the first operation mode, the imaging unit reads out signals from all pixels in the plurality of pixels. In the second operation mode, the imaging unit reads out signals by aggregating two or more pixels in the plurality of pixels or by thinning out some of the pixels.

[0108] In a seventh aspect, the imaging device according to any one of the first to sixth aspects includes a temperature sensor capable of measuring a temperature of the imaging section, and the temperature acquisition section acquires the temperature of the imaging section from the temperature sensor.

[0109] In an eighth aspect, the imaging device of any of the first to sixth aspects is provided with a temperature sensor capable of measuring the temperature of a part other than the imaging unit, and the temperature acquisition unit calculates the temperature of the imaging unit based on the measurement result by the temperature sensor. [Industrial Applicability]

[0110] The present disclosure is applicable to various types of imaging devices that perform imaging operations in a plurality of operation modes. [Explanation of symbols]

[0111] 100 Digital Camera 115 Image Sensor 135 Control Unit 165 Temperature Sensor 166 Exterior temperature sensor Ts Thermal stop temperature Tc PDAF limit temperature Tr PDAF restart temperature

Claims

1. An imaging device that performs imaging operations in a plurality of operation modes, an imaging unit that captures an object image via an optical system and generates image data; a temperature acquisition unit that acquires a temperature of the imaging unit; a control unit that switches the plurality of operation modes based on a temperature of the imaging unit, the plurality of operation modes include a first operation mode and a second operation mode in which power consumption by the imaging unit is smaller than that in the first operation mode, the control unit changes the operation mode of the imaging device from the first operation mode to the second operation mode when a temperature of the imaging unit rises to a first temperature during an imaging operation in the first operation mode; The first temperature is lower than a temperature at which execution of a predetermined function in the imaging device is restricted. Imaging device.

2. After changing the operation mode of the imaging device from the first operation mode to the second operation mode, the control unit When the temperature of the imaging unit drops to a second temperature lower than the first temperature during imaging operation in the second operation mode, the operation mode of the imaging device is changed from the second operation mode back to the first operation mode. The imaging device according to claim 1 .

3. The first and second operation modes are operation modes in which power consumption is different with respect to autofocus operation in the imaging unit. The imaging device according to claim 1 .

4. In the first operation mode, the imaging device performs an autofocus operation by a phase difference detection method, In the second operation mode, the imaging device performs an autofocus operation by at least one of a contrast detection method, a depth from defocus (DFD) method, and a distance measurement method using active sensing. The imaging device according to claim 3 .

5. The imaging device performs an operation of capturing a still image in the first and second operation modes. The imaging device according to claim 3 .

6. the first and second operation modes are operation modes in which the power consumption of the imaging unit is different with respect to reading of signals output from a plurality of pixels included in the imaging unit, In the first operation mode, the imaging unit reads out signals from all pixels in the plurality of pixels; In the second operation mode, the imaging unit reads out signals by aggregating two or more pixels among the plurality of pixels or by thinning out some of the pixels. The imaging device according to claim 1 .

7. A temperature sensor capable of measuring a temperature of the imaging unit is provided, The temperature acquisition unit acquires the temperature of the imaging unit from the temperature sensor. The imaging device according to claim 1 .

8. a temperature sensor capable of measuring a temperature of a portion of the imaging device other than the imaging unit; The temperature acquisition unit calculates the temperature of the imaging unit based on a measurement result by the temperature sensor. The imaging device according to claim 1 .

Images