Flash apparatus, imaging apparatus, and light emission control method

Abstract

The flash device includes a light emitting unit, a communication unit that receives required light output and exposure time information specified by an imaging device, and a synchronization signal for synchronizing exposure timing and light emitting timing of the imaging device, and a control unit that controls the light emitting unit to emit light based on the required light output and the exposure time information. A light emission start timing of the light emitting unit based on the synchronization signal is determined, and the light emitting unit is caused to flash and emit light at the determined light emission start timing.

Description

Technical Field

[0001] This technology relates to a flash device, an imaging device, and a light emission control method, and more particularly, to a light emission control method for a flash device. Background Technology

[0002] Shutter systems such as single-lens reflex cameras, which expose the imaging element through a focal plane shutter, and electronic shutter systems, which provide the exposure time through the operation of a CMOS image sensor with a rolling shutter, typically used in consumer digital cameras, have curtain speeds or readout speeds.

[0003] Therefore, the flash of a flash device, which aids in exposure, needs to occur during the so-called full exposure period, when the imaging surface is completely exposed. Otherwise, uneven exposure will occur.

[0004] When attempting to fire a flash from a flash unit for the entire exposure period, a speed limit is imposed on the high-speed range of shutter speeds. This speed limit is called the sync speed.

[0005] As disclosed in Patent Document 1 below, the flash emission of the flash device is sampled and metered, the outline of the emission waveform is stored in the camera, and the synchronization speed is set and made available by effectively utilizing the emission characteristics of the flash lamp.

[0006] The following patent document 2 discloses the relationship between stored flash emission and light output, and adjusts the exposure timing to determine the start and end of the exposure to ensure that the integral of the stored emission waveform matches the optimal exposure.

[0007] Citation List

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2003-172970

[0010] Patent Document 2: Japanese Patent No. 5541938 Summary of the Invention

[0011] Problems to be solved by the present invention

[0012] Incidentally, at shutter speeds exceeding the sync speed applied to flash emission, a stable light output can be produced throughout the entire travel time of the shutter curtain or the entire exposure period from the start to the end of a rolling shutter by employing a emission mode commonly known as flat emission.

[0013] However, flat lighting requires a stable light output throughout the entire period from the start of the front curtain travel to the end of the rear curtain travel. This makes it difficult to efficiently utilize the energy of the flash lighting device to contribute to the exposure, and it results in some disadvantages compared to using flash lighting, such as a significant reduction in the coverage area of ​​the light emitted.

[0014] Therefore, this disclosure proposes a technique that enables flash emission to aid exposure even at shutter speeds exceeding the sync speed.

[0015] Solution to the problem

[0016] The flash device according to this technology includes: a light-emitting unit; a communication unit that receives desired light output and exposure time information specified by an imaging device, and a synchronization signal for synchronizing the exposure timing and light emission timing of the imaging device; and a control unit that, based on the desired light output and exposure time information, determines the light emission start timing of the light-emitting unit based on the synchronization signal, and causes the light-emitting unit to flash at the determined light emission start timing.

[0017] Required light output is the information about light output sent by the imaging device in order to properly capture an image of the subject. Exposure time information can be any information that determines the exposure time for the current imaging process. For example, exposure time information can be the exposure time itself, or a shutter speed value from which the exposure time can be calculated.

[0018] Note that when TTL (Time-to-Lens) settings are enabled, the control unit controls the light output based on information sent by the imaging device. However, when manual settings are enabled, the control unit can control the light intensity based on the light intensity value set on the flash side.

[0019] Furthermore, the imaging device according to this technology includes: a communication unit that sends the required light output, exposure time information and a synchronization signal to a flash device, the synchronization signal being used to synchronize the exposure timing and the emission timing; the flash device includes a control unit that, based on the required light output and exposure time information, determines the emission start timing of the emission unit based on the synchronization signal, and causes the emission unit to emit light at the determined emission start timing.

[0020] That is, information used to determine the timing of the start of light emission is sent to the flash device. Attached Figure Description

[0021] Figure 1 This is an illustration used to describe a camera and an external flash according to embodiments of the present technology.

[0022] Figure 2This is a block diagram of a camera and an external flash according to an embodiment.

[0023] Figure 3 This is a flowchart of the processing during the imaging standby period in a camera according to a comparative example.

[0024] Figure 4 This is a flowchart of the processing from the start of imaging in the camera of the comparative example.

[0025] Figure 5 This is a flowchart of the processing during the imaging standby period in the external flash of the comparative example.

[0026] Figure 6 This is a flowchart illustrating the process starting from the main light emission control in the external flash unit of the comparative example.

[0027] Figure 7 It is a diagram used to describe flashing and flat emission.

[0028] Figure 8 This is a flowchart of the processing during the imaging standby period in the camera according to the first embodiment.

[0029] Figure 9 This is a flowchart of the processing in the camera according to the first embodiment, starting from the image formation.

[0030] Figure 10 This is a flowchart of the processing during the imaging standby period in the external flash according to the first embodiment.

[0031] Figure 11 This is a flowchart of the process starting from the main light emission control in the external flash lamp according to the first embodiment.

[0032] Figure 12 This is a diagram used to describe the fully synchronous control according to the first embodiment.

[0033] Figure 13 This is a diagram used to describe the semi-synchronous control according to the first embodiment.

[0034] Figure 14 This is a flowchart of the full synchronization determination according to the first embodiment.

[0035] Figure 15 This is a diagram used to describe the threshold table according to the first embodiment.

[0036] Figure 16 This is a diagram illustrating the interpolation process using a threshold table according to the first embodiment.

[0037] Figure 17 This is a flowchart of semi-synchronous control according to the first embodiment.

[0038] Figure 18 This is a diagram used to describe the timeline according to the first embodiment.

[0039] Figure 19 This is a diagram illustrating the interpolation process according to the usage schedule of the first embodiment.

[0040] Figure 20 This is a diagram illustrating the interpolation process according to the usage schedule of the first embodiment.

[0041] Figure 21 This is a diagram illustrating the interpolation process according to the usage schedule of the first embodiment.

[0042] Figure 22 It is a diagram used to describe when a delay occurs in the emission waveform under semi-synchronous control.

[0043] Figure 23 It is a diagram used to describe when a delay occurs in the emission waveform under semi-synchronous control.

[0044] Figure 24 This is a diagram used to describe the light output control of an Xe tube.

[0045] Figure 25 This is a diagram used to describe the semi-synchronous control A and semi-synchronous control B according to the second embodiment.

[0046] Figure 26 This is a flowchart of semi-synchronous control according to the second embodiment.

[0047] Figure 27 This is a diagram used to describe the maximum effective light output table according to the second embodiment.

[0048] Figure 28 This is a flowchart of the semi-synchronous control B according to the second embodiment.

[0049] Figure 29 This is a flowchart of the semi-synchronous control B according to the second embodiment.

[0050] Figure 30 This is a diagram illustrating the actual light output table for high-speed, low-emission applications according to the second embodiment.

[0051] Figure 31 This is a diagram used to describe the estimated low emission stop schedule according to the second embodiment. Detailed Implementation

[0052] The embodiments will be described below in the following order.

[0053] <1. Examples of Imaging System Structures>

[0054] <2. Comparative Examples>

[0055] <3. Processing according to the first embodiment>

[0056] <4. Processing according to the second embodiment>

[0057] <5. Operation of a multi-lamp system>

[0058] <6. Conclusions and Variations>

[0059] <1. Examples of Imaging System Structures>

[0060] Figure 1 This is a diagram illustrating an example of the configuration of an imaging system to which this technology is applied.

[0061] like Figure 1 As shown in the diagram, the imaging system 11 includes a camera 12, an external flash 13A attached to the main body of the camera 12, and external flashes 13B-1 and 13B-2 not attached to the camera 12.

[0062] Note that external flash units 13B-1 and 13B-2 can also be attached to camera 12, and unless otherwise specified, they will be referred to as external flash unit 13 below.

[0063] In addition, external flash units 13B-1 and 13B-2 are collectively referred to as external flash unit 13B.

[0064] The camera 12 includes a display unit 21 and an operation unit 22.

[0065] The display unit 21 displays images captured by the camera 12, various setting screens, etc.

[0066] The operation unit 22 is equipped with a shutter button that is operated to allow the camera 12 to capture images, a setting button that is operated to make various settings using the setting screen displayed on the display unit 21, etc.

[0067] The external flash 13 includes a display unit 23 (23A, 23B-1, 23B-2) and an operation unit 24 (24A, 24B-1, 24B-2). The display unit 23 displays a setting screen in which the external flash 13 is configured.

[0068] The operation unit 24 is equipped with a setting button, which is operated to configure the external flash 13 using the setting screen displayed on the display unit 23.

[0069] In this imaging system 11, the external flash 13A can communicate with the camera 12 via electrical contacts of an attachment provided in the camera 12.

[0070] On the other hand, in the imaging system 11, external flashes 13B-1 and 13B-2 can communicate with external flash 13A via wireless communication using radio waves.

[0071] That is, external flash 13A operates in response to direct communication with camera 12 and sends commands to external flashes 13B-1 and 13B-2. When a command is received, external flashes 13B-1 and 13B-2 can begin operation.

[0072] Therefore, external flash unit 13A may be referred to as "commander" in the following text, while external flash units 13B-1 and 13B-2 may be referred to as "receivers".

[0073] Figure 2 This is a block diagram illustrating an example of the functional configuration of the imaging system 11.

[0074] like Figure 2 As shown in the diagram, in the imaging system 11, when the external flash 13A is attached to the camera 12, the camera 12 and the external flash 13A are electrically connected via multiple signal lines such as XON, DATA, CLK and GND, thereby enabling communication between the camera 12 and the external flash 13A.

[0075] Furthermore, the external flash 13A, which acts as a command unit, and the external flash 13B, which acts as a receiver, can communicate with each other wirelessly.

[0076] The camera 12 includes a lens unit 31, an imaging element 32, an imaging circuit 33, a detection circuit 34, a signal processing circuit 35, a recording system 36, a display unit 37, a timing generator (TG) circuit 39, an exposure / light output calculation and control circuit 40, and a focus calculation and control circuit 41, serving as components for capturing images of a subject. Furthermore, an operation unit 42 and a control unit 43 are provided as components for controlling the aforementioned imaging operations. Additionally, a communication unit 48 is provided for synchronization with the external flash 13.

[0077] Lens unit 31 includes lenses such as zoom lenses and focusing lenses, as well as an aperture (aperture mechanism). Light from the subject (incident light) is focused onto imaging element 32 through lens unit 31.

[0078] Imaging element 32 includes, for example, an image sensor of the charge-coupled device (CCD) type, complementary metal-oxide-semiconductor (CMOS) type, etc.

[0079] Imaging element 32 outputs an electrical signal obtained from the light received through photoelectric conversion. Imaging circuit 33 performs processing on this electrical signal, such as correlated double sampling (CDS) and automatic gain control (AGC). In addition, imaging circuit 33 performs analog-to-digital (A / D) conversion.

[0080] The detection circuit 34 performs detection processing for autofocus (AF), auto exposure (AE), etc., and provides the detection information to the exposure / light output calculation and control circuit 40 and the focus calculation and control circuit 41.

[0081] The focusing calculation and control circuit 41 performs calculations for AF control based on the detection information, and performs AF operation by driving and controlling the focusing lens of the lens unit 31 according to the calculation results.

[0082] Exposure / light output calculation and control circuit 40 performs exposure control based on detection information. Exposure control includes aperture control of lens unit 31, shutter speed control of imaging element 32, and gain control of imaging circuit 33.

[0083] Regarding shutter speed control, the exposure / light output calculation and control circuit 40 controls the TG circuit 39 to adjust the shutter timing of the imaging element 32, that is, the timing of the front curtain and the rear curtain, to achieve the desired exposure time.

[0084] In addition, to synchronize with the external flash unit 13, the exposure / light output calculation and control circuit 40 also performs processing to send the required light output indicating the necessary light intensity, exposure time information indicating the exposure time, and signals synchronizing the light emission timing with the shutter release to the external flash unit 13 via the communication unit 48. The exposure time information may include a time indicating the exposure period or a value indicating the shutter speed.

[0085] The signal processing circuit 35 performs various types of signal processing on the digital signal (captured image signal) received from the imaging element 32 as a development process. Specifically, the signal processing circuit 35 performs processes such as preprocessing, synchronization processing, YC generation processing, resolution conversion processing, and codec processing.

[0086] Image data obtained through development processing and further converted into a predetermined file format in signal processing circuit 35, or so-called RAW image data that has not undergone development processing, is recorded in recording system 36. Recording system 36, for example, records and plays back images on recording media using non-volatile memory. Recording system 36, for example, performs processing such as recording image files such as moving image data, still image data, thumbnails, etc., on recording media.

[0087] The display unit 37 is configured to display various types of information to the user of the camera 12, and specifically is a display panel or viewfinder installed in the camera 12.

[0088] Display unit 37 displays various types of information on the display screen based on instructions from control unit 43. For example, image data of captured images, whose resolution has been converted by camera signal processing circuit 35 for display, is provided to display unit 37, and display unit 37 displays the image data of the captured images in response to instructions from control unit 43. That is, it displays images such as images through the lens during imaging standby or motion images during video recording. Furthermore, display unit 37 displays replay images of image data read from the recording medium by recording system 36. In addition, display unit 37 displays various operation menus, icons, messages, etc., on the screen based on instructions from control unit 43; that is, a graphical user interface (GUI).

[0089] The operation unit 42 collectively represents the input device used by the user to input various operations. More specifically, the operation unit 42 represents various control elements mounted on the main body of the camera 12. User operations are detected by the operation unit 42, and signals corresponding to the input operations are sent to the control unit 43. The operation unit 42 can be used not only as control elements but also as a touch panel. For example, a touch panel can be formed on the display panel, which serves as the display unit 37, to perform various operations by using touch panel operations such as icons and menus displayed on the display panel. Alternatively, the operation unit 42 can use a touchpad or the like to detect user tapping operations. Furthermore, the operation unit 42 can be configured as a receiving unit for external operation devices such as a separate remote control.

[0090] The control unit 43 includes a microcomputer (arithmetic processing unit) equipped with a central processing unit (CPU) 44, a read-only memory (ROM) 45, a random access memory (RAM) 46, and an electrically erasable programmable read-only memory (EEPROM) 47.

[0091] RAM 46 is used for temporary storage of data, programs, etc., and serves as the work area for various types of data processing performed by the CPU 44.

[0092] ROM 45 and EEPROM 47 are used to store the operating system (OS) for each unit controlled by CPU 44, application programs for various operations, firmware, various settings, etc.

[0093] The control unit 43 controls the entire camera 12 by executing programs stored in ROM 45, EEPROM 47, etc.

[0094] For example, in response to user operations, the control unit 43 controls necessary units to perform imaging operations, recording operations, operations for replaying recorded image files, user interface operations, etc.

[0095] Next, the configuration of the external flash 13 will be described.

[0096] The external flash 13A, which acts as a command unit, includes an operation signal acquisition unit 61A, a display control unit 62A, a storage unit 63A, a light emission control unit 64A, a light emission unit 65A, a wireless communication unit 66A, a communication unit 67A, a light receiving unit 68A, and a control unit 69A.

[0097] When operating Figure 1 When the operation unit 24A is operated as shown in the diagram, the operation signal acquisition unit 61A acquires the operation signal corresponding to the operation. For example, when the setting button of the operation unit 24A is operated, the operation signal acquisition unit 61A acquires the operation signal indicating that the setting associated with the setting button has been requested, and provides the operation signal to the control unit 69A.

[0098] The display control unit 62A performs operations under the control of the control unit 69A. Figure 1 The display unit 23A shown in the diagram displays the control settings screen, etc.

[0099] The storage unit 63A stores various data required by the control unit 69A to control the external flash 13A, setting information about the settings applied to the external flash 13A, etc.

[0100] Under the control of control unit 69A, light emission control unit 64A controls the light emission of light emission unit 65A based on the light emission trigger output from camera 12. That is, it performs light emission corresponding to the full pressing operation of the shutter button in camera 12.

[0101] The light-emitting unit 65A emits light under the control of the light-emitting control unit 64A.

[0102] The light receiving unit 68A detects the light emitted from the light emitting unit 65A and feeds back information about the light intensity to the light emitting control unit 64A.

[0103] Under the control of the control unit 69A, the wireless communication unit 66A communicates wirelessly with the external flashlight 13B, which acts as a receiver. This wireless communication can be radio wave communication or optical communication.

[0104] Note that the external flash 13A, which acts as a command unit, and the external flash 13B, which acts as a receiver, can communicate with each other via wired communication.

[0105] Under the control of the control unit 69A, the communication unit 67A communicates with the camera 12 via four signal lines.

[0106] The control unit 69A performs the necessary control to synchronize the external flash 13A with the image capture of the camera 12.

[0107] The control unit 69A includes a microcomputer (arithmetic processing unit) equipped with a CPU, ROM, RAM, EEPROM, etc. RAM is used for temporary storage of data, programs, etc., serving as the working area for various types of data processing performed by the CPU. ROM and EEPROM are used for storing the OS for controlling each unit, application programs for various operations, firmware, various settings, etc.

[0108] The control unit 69A controls the entire external flash 13A by executing programs stored in ROM, EEPROM, etc. For example, the control unit 69A communicates with the camera 12, controls the light emission based on instructions to the light emission control unit 64A in response to the communication, and issues display instructions to the display control unit 62A, etc.

[0109] Note that the external flash 13B, which acts as a receiver, has similar components to the external flash 13A, which acts as a command unit.

[0110] Although the components of external flash 13A have been described above, external flash 13B has similar components, so its description will be omitted.

[0111] However, in the accompanying drawings, the symbol "B" is assigned to the block on the receiver side, instead of the symbol "A" being assigned to the block on the command side (e.g., control unit 69A and control unit 69B).

[0112] Furthermore, when describing the components of the external flash 13 without distinguishing between the command unit and the receiver, neither “A” nor “B” will be specified in the following text, just as with “control unit 69”.

[0113] Notice, Figure 2 The components of the camera 12 and external flash 13 shown in the diagram are merely examples. The camera 12 and external flash 13 according to this embodiment do not need to include all the components shown in the diagram, and may include components not shown.

[0114] <2. Comparative Examples>

[0115] First, as a comparative example, an example of selectively flashing and flattening light emission in an external flash lamp 13 will be described.

[0116] Figure 3 and Figure 4Illustrated examples of processing on 12 sides of a camera. Figure 5 and Figure 6 This diagram illustrates an example of processing on the side of the external flash unit (13). Note that... Figure 3 and Figure 4 The processing in the camera 12 shown in the diagram is mainly performed by the control unit 43 and the exposure / light output calculation and control circuit 40. Furthermore, Figure 5 and Figure 6 The processing in the external flash 13 shown in the diagram is mainly performed by the control unit 69 (69A, 69B).

[0117] Figure 3 The diagram illustrates the processing performed during the imaging standby period in camera 12.

[0118] During the imaging standby period, in step S101, the camera 12 performs metering and exposure calculations to determine the shutter speed, aperture value, and sensitivity (gain). Then, the camera 12 performs exposure control based on the determined shutter speed, aperture value, and sensitivity.

[0119] Note that, although not shown, when selecting manual exposure mode, aperture priority mode, shutter speed priority mode, etc., the user-selected control value for priority is applied for each mode.

[0120] During imaging standby, in step S102, the camera 12 sends internal information about the camera 12 to the attached external flash 13A via serial communication from the communication unit 48. This internal information includes an exposure control value determined as a result of the exposure calculation performed on the camera 12 side in step S101.

[0121] Furthermore, the external flash 13A sends its internal status information to the camera 12 via serial communication. In step S103, the camera 12 receives the internal status information from the external flash 13A.

[0122] In step S104, the camera 12 causes the display unit 37 to output a display based on the internal state information of the flash lamp side.

[0123] For example, when camera 12 is notified that external flash 13 is charging, an icon indicating "charging" is displayed on display unit 37 of camera 12, allowing the user to recognize the status. When the flash is emitted while charging is in progress, the coverage area of ​​full illumination is smaller compared to when fully charging, so it is preferable to indicate to the user that charging is in progress.

[0124] Furthermore, although not shown in the flowchart, the camera 12 is able to lock shutter release when the external flash 13 is not fully charged, so as to prevent the start of imaging even when the shutter button is pressed.

[0125] When the camera 12 is in imaging standby mode and the shutter button is not pressed, repeat the above steps S101 to S104.

[0126] When the shutter button of camera 12 is half-pressed, the processing in camera 12 proceeds from step S105 to step S106, in which autofocus control is performed. That is, focus calculation is performed to drive and control the focusing lens, thereby bringing the subject into focus.

[0127] In step S107, the camera 12 detects whether focus has been achieved. Before focus is achieved, autofocus control will continue, and the shutter button will remain half-pressed.

[0128] When focusing is detected, in step S108, the camera 12 detects that the shutter button is fully pressed. While the shutter button remains partially pressed, the processes of steps S101 to S107 are repeated.

[0129] When the shutter button is detected to be fully pressed, the processing in camera 12 proceeds to... Figure 4 The imaging process, as shown in the diagram, begins.

[0130] When the shutter button is fully pressed, Figure 4 In step S120, the camera 12 branches the processing based on whether the via-lens (TTL) flash mode is enabled.

[0131] When automatic dimming is enabled in TTL flash mode, in step S121, the camera 12 performs a TTL pre-flash sequence to determine the light output required to achieve correct exposure of the subject, that is, the light output required for the external flash 13.

[0132] In manual flash mode, the TTL pre-flash sequence in step S121 is not performed.

[0133] In step S122, the camera 12, according to... Figure 3 The shutter speed determined in step S101 is used to determine the illumination mode.

[0134] The camera 12 compares the shutter speed with the sync speed, and when the shutter speed exceeds the sync speed, it activates flat illumination as the illumination mode. On the other hand, when the shutter speed is lower than or equal to the sync speed, it activates flash illumination as the illumination mode.

[0135] Synchronization speed, flat illumination, and flash illumination will be discussed later. Figure 7 describe.

[0136] When flat illumination is enabled, in step S123, the camera 12 sends a command for flat illumination and the desired light output to the external flash 13.

[0137] When flash illumination is enabled, in step S124, camera 12 sends a command for flash illumination and the desired light output to external flash unit 13.

[0138] Next, in step S125, the camera 12 sends a synchronization signal XON to synchronize the illumination timing of the external flash 13 with the exposure timing used for imaging.

[0139] After step S126, in response to the user's shutter button operation, the camera 12 captures a still image and performs image processing and recording processing on the recording medium in sequence.

[0140] That is, in step S126, the camera 12 controls the start of the exposure and the end of the exposure after the exposure period has passed. In other words, the imaging element 32 is exposed to capture a still image.

[0141] Then, in camera 12, in step S127, signal processing circuit 35 performs signal processing such as development processing on the captured image signal obtained by exposure, and in step S128, recording system 36 performs recording processing to record still image data.

[0142] In response to the above processing in camera 12, external flash 13 performs... Figure 5 and Figure 6 The process is illustrated in the diagram. First, Figure 5 The diagram illustrates the processing performed during imaging standby on the side of the external flash 13.

[0143] In step S201, charging control is performed on the external flash lamp 13. This includes charging the main capacitor that stores the charge used by the light-emitting units 65 (65A, 65B) for emitting light, and determining whether the capacitor is fully charged.

[0144] In step S202, the external flash 13 receives imaging control values ​​from the camera 12. That is, the external flash 13 receives internal information about the camera 12, including... Figure 3 The exposure control value sent by the camera 12 in step S102.

[0145] In step S203, the external flash 13 sends its internal status to the camera 12. For example, it sends an internal status such as charging or fully charged. (As described above...) Figure 3In step S104, the camera 12 receives the internal state.

[0146] In step S204, the external flash 13 displays various information on the display unit 23. For example, it displays the charging status and the maximum light output based on the external flash 13, as well as the light coverage calculated based on the exposure control value received from the camera 12.

[0147] Figure 6 The diagram illustrates the processing during imaging on the flash side, particularly the processing during the main emission period. This processing corresponds to... Figure 4 The diagram shows the processing after the imaging process begins.

[0148] In step S220, the external flash 13 receives the illumination pattern and desired light output from the camera 12. These are in Figure 4 In step S123 or step S124, information is sent from camera 12.

[0149] exist Figure 6 In step S221, the external flash 13 branches the processing based on the specified illumination mode.

[0150] When flash illumination is enabled, in step S222, the external flash unit 13 performs flash illumination synchronization control. That is, the conditions for enabling flash illumination are met.

[0151] When flat illumination is enabled, in step S223, the external flash 13 performs flat illumination synchronization control to enable the flat illumination condition.

[0152] Then, illumination control is performed in step S224. In this case, the external flash 13 starts and stops emitting light at a timing determined according to the synchronization signal XON.

[0153] In the above processing example, flash emission or flat emission is selected based on shutter speed (exposure time). However, flat emission has drawbacks.

[0154] Figure 7 The diagram illustrates the relationship between the emission waveforms 70 and 70F and the exposure periods based on front curtain timings 71R and 71G and rear curtain timings 72R and 72G in both low and high shutter speed systems, in both rolling shutter and global shutter systems. The high shutter speed case corresponds to the case where the shutter speed is higher than or equal to the sync speed in the rolling shutter system.

[0155] The front curtain timing 71R and rear curtain timing 72R correspond to the timing in the rolling shutter system, while the front curtain timing 71G and rear curtain timing 72G correspond to the timing in the global shutter system. The emission waveform 70 corresponds to the waveform of flash emission, and the emission waveform 70F corresponds to the waveform of flat emission.

[0156] First, consider rolling shutter, where a low shutter speed (lower than or equal to the sync speed) is used to fire a flash during the so-called full exposure period, ensuring the image plane is fully exposed. This prevents uneven exposure.

[0157] However, when attempting to fire a flash over the entire exposure period, a speed limit is imposed on the high-speed range of shutter speeds. This speed limit is called the sync speed.

[0158] When the shutter speed exceeds the sync speed, the flash cannot fully illuminate during the entire exposure period, resulting in uneven exposure. To solve this problem, a flat flash is implemented.

[0159] As shown in the attached diagram at high shutter speeds, a stable light output is produced as a flat emission throughout the entire travel time of the shutter curtain, or the entire exposure period from the start to the end of a rolling shutter, to expose the imaging surface. This prevents color unevenness.

[0160] However, flat-panel illumination requires a stable light output throughout the entire period from the start of the front curtain travel to the end of the rear curtain travel. This makes it unable to efficiently utilize the energy of the flash equipment to contribute to the exposure, and results in a significant reduction in the coverage area of ​​the illumination compared to the use of flash.

[0161] In practical use, in situations requiring higher shutter speeds, such as brighter outdoor conditions, the light emitted from clip-on flash devices cannot reach the subject, necessitating the use of larger, less portable flash devices.

[0162] Furthermore, flat emission requires time to achieve stable light output. Therefore, as illustrated in the attached diagram, the front curtain timing 71 must be reached while achieving stable light output through emission within a certain time period before reaching the front curtain.

[0163] <3. Processing according to the first embodiment>

[0164] In order to eliminate the disadvantages of flat light emission as described above, this embodiment adopts a method in which the light emission timing is actively controlled by an external flash 13 compatible with a camera 12 employing a global shutter system.

[0165] In the following text, a processing example as a first embodiment will be described.

[0166] Figure 7 The diagram also illustrates the global shutter system, but at low shutter speeds, the flash emission waveform 70 falls almost entirely within the time interval between the front curtain timing 71G and the rear curtain timing 72G.

[0167] At high shutter speeds, the exposure period (full exposure period) defined by the front curtain timing 71G and the rear curtain timing 72G takes the form of a portion of the exposure time (shadow portion) extracted from the flash emission waveform 70. In this case, the extraction timing is controlled within the full exposure period to achieve exposure using appropriate light output. In other words, the emission timing is controlled to achieve proper extraction.

[0168] With global shutter speed, even at shutter speeds higher than or equal to the sync speed of the aforementioned rolling shutter, sufficient light output can be achieved compared to flat lighting by synchronizing the period of greater light output during flash with the exposure period.

[0169] A processing example of this embodiment will be described.

[0170] Figure 8 and Figure 9 The illustration shows an example of processing on 12 sides of the camera, while Figure 10 and Figure 11 This diagram illustrates an example of processing on side 13 of the external flash unit. Note that... Figure 8 and Figure 9 The processing in the camera 12 shown in the diagram is mainly performed by the control unit 43 and the exposure / light output calculation and control circuit 40. Furthermore, Figure 10 and Figure 11 The processing in the external flash 13 shown in the diagram is mainly performed by the control unit 69 (69A, 69B).

[0171] Figure 8 This diagram illustrates the processing during image standby in camera 12. Note that, compared to... Figure 3 Identical steps are represented by the same step number to avoid redundancy in the description.

[0172] Figure 8 and Figure 3 The processing is basically similar. During imaging standby, in step S101, the camera 12 performs metering and exposure calculations to determine the shutter speed, aperture value, and sensitivity (gain), and performs exposure control. Then, in step S102, internal information about the camera 12, such as the exposure control value, is sent from the communication unit 48 to the external flash 13.

[0173] In step S103, the camera 12 receives internal status information from the external flash 13.

[0174] Then, in step S104A, the camera 12 outputs a display based on the flash's internal status information. In this case, with Figure 3The difference in step S104 is that, in addition to displaying the charging status, it also outputs information such as the possibility of synchronous operation and the maximum coverage range of the required light output. These will... Figure 10 As described in the description.

[0175] Steps S105 to S108 and Figure 3 Similarly, when the shutter button is half-pressed, the camera 12 performs autofocus control, and when the shutter button is fully pressed, it performs processing after the image begins to be captured. Figure 9 (processing in the middle).

[0176] When the shutter button is fully pressed, Figure 9 In step S150, the camera 12 branches the processing based on whether the TTL flash mode is enabled.

[0177] When automatic dimming is enabled in TTL flash mode, the camera 12 performs a TTL pre-flash sequence in step S151 to determine the light output required to achieve correct exposure of the subject, that is, the light output required for the external flash 13.

[0178] In manual flash mode, the TTL pre-flash sequence in step S151 is not performed.

[0179] In step S152, the camera 12 will be based on... Figure 8 The shutter speed, exposure time, margin time, and required light output determined in step S101 are sent to the external flash 13.

[0180] Shutter speed can be used as a substitute for the exposure time in the data sent from camera 12 to external flash 13. However, microsecond-level precision is required because the time interval between the start and end of the exposure is extracted from the flash waveform.

[0181] As described below, the margin time corresponds to the time defined between the camera 12 and the external flash 13, which is the time from the activation of the sync signal XON to the start of exposure. As a margin time, for example, it is a predetermined value of a few milliseconds sent from the camera 12 to the external flash 13.

[0182] The required light output corresponds to the light output needed for proper exposure of the subject in order to achieve correct imaging.

[0183] Note that in manual flash mode, the light output setting on the external flash 13 side corresponds to the light output required for the exposure.

[0184] Next, in step S153, the camera 12 activates a synchronization signal XON to synchronize the emission timing of the external flash 13 with the exposure timing of the imaging at a time that is adjusted to be earlier than the exposure start time by the margin time.

[0185] After step S154, in response to the user's shutter button operation, the camera 12 captures a still image and sequentially performs image processing and recording processing on the recording medium.

[0186] That is, in step S154, the camera 12 controls the start of exposure and the end of exposure after the exposure period ends. In other words, the imaging element 32 is exposed to capture a still image.

[0187] Then, in camera 12, in step S155, signal processing circuit 35 performs signal processing such as development processing on the captured image signal obtained by exposure, and in step S156, recording system 36 performs recording processing to record still image data.

[0188] In response to the above processing in camera 12, external flash 13 performs... Figure 10 and Figure 11 The process is illustrated in the diagram. First, Figure 10 The diagram illustrates the processing during the imaging standby period on the side of the external flash 13.

[0189] The charging control in step S201 and the receiving of imaging control values ​​from camera 12 in step S202 Figure 5 Similar to that in [the text].

[0190] In step S210, the external flash 13 performs a asynchronous control determination. This is a determination of whether the external flash 13 can emit light according to the exposure time received from the camera 12 and the required light output. Specifically, a timer is used to determine whether the required light output received from the camera 12 is achieved under the semi-synchronous control described later.

[0191] In step S203A, status information regarding the external flash 13 itself is sent to the camera 12. The camera 12, in the above... Figure 8 In step S103, status information is received, and in step S104A, a display based on the received information is output.

[0192] In this case, as status information about the external flash 13, for example, an internal status such as charging or fully charged is sent.

[0193] In addition, the status information also includes information related to the asynchronous control determination in step S210.

[0194] That is, the status information includes information indicating that it is asynchronous control. In this case, the shutter speed maintained on the side of the external flash 13 is sent to the camera 12 as the maximum side shutter speed limit value (described later) to ensure light emission control, and the camera 12 can set the maximum shutter speed for light emission on the graph based on this shutter speed, or set the shutter speed setting limit in shutter speed priority mode or manual exposure mode.

[0195] Furthermore, when no shutter speed limit is set in the above figure, and the shutter speed calculated on the camera 12 side exceeds the shutter speed limit value, a warning icon can be displayed on the camera 12 to notify the user that the shutter speed cannot guarantee performance and is incompatible with the synchronized dimming of the attached external flash 13.

[0196] Furthermore, as a determination of asynchronous control, when the shutter speed is outside the range of asynchronous control (i.e., when the shutter speed is compatible with synchronous control), information about the illumination coverage area can be included in the status information. For example, camera 12 displays the illumination coverage area under semi-synchronous control, as described later, to inform the user of the illumination coverage area.

[0197] In this case, the effective light output, as described later, is used as the maximum light output used in the calculation of the luminous coverage.

[0198] In step S204, the external flash 13 displays various information on the display unit 23. For example, it displays the charging status and the range of light emission.

[0199] Figure 11 The diagram illustrates the processing during imaging on the flash side, particularly the processing during the main emission period. This processing corresponds to... Figure 8 Processing after the imaging process begins.

[0200] In step S250, the external flash 13 receives the exposure time, margin time, and desired light output from the camera 12. These are in... Figure 9 The information sent from camera 12 in step S152.

[0201] In step S251, the external flash 13 performs a full synchronization determination. This determines whether the light is emitted under full synchronization control or under semi-synchronization control.

[0202] Here, we will refer to Figure 12 and Figure 13 Describe fully synchronous control and semi-synchronous control.

[0203] Figure 12 A diagram illustrating full synchronization control.

[0204] exist Figure 12In this model, the emitted waveform 70 falls within the exposure period from the front curtain timing 71G to the rear curtain timing 72G, and it is assumed that the entire emission contributes to the exposure. This is a mode in which the time interval is not extracted from the emitted waveform 70 of the flash emission. This mode is thought to be possible when the exposure time is long or the flash output is low.

[0205] Under this fully synchronous control, the light only needs to start emitting light after the front curtain timing 71G and end emitting light at the appropriate timing.

[0206] In the accompanying drawings, the IGBT and TRIG signals are transmitted from the control unit 69 to the light-emitting control unit 64. The light-emitting control unit 64 controls the start and end of light emission from the light-emitting unit 65 based on the IGBT and TRIG signals.

[0207] After the synchronization signal XON is activated by the camera 12 at time tm0, the control unit 69A outputs the IGBT signal and the TRIG signal.

[0208] exist Figure 12 and Figure 13 The timing of time points tm0 to tm5 in the data has the following meanings.

[0209] At time point tm0, the synchronization signal XON is activated.

[0210] At time tm1, the signal IGBT is turned on.

[0211] Time point tm2 indicates the timing of the front curtain.

[0212] At time tm3, signal TRIG is activated, and the light-emitting control unit 64 causes the light-emitting unit 65 to start flashing.

[0213] At time tm4, the IGBT signal is turned off, and the light-emitting control unit 64 causes the light-emitting unit 65 to stop flashing. Note that even when the flashing control is executed, the afterglow will last for a very short time.

[0214] Time point tm5 indicates rear curtain timing.

[0215] The margin time Tmg sent from camera 12 represents the time between time point tm0 and time point tm2, which serves as the timing for the front curtain.

[0216] Time T1 represents the time between time point tm0 and time point tm1.

[0217] Time T2 represents the time between the IGBT and TRIG signals of control unit 69, and is, for example, a fixed time.

[0218] Time T3 represents the time between the front curtain timing 71G and the rear curtain timing 72G, that is, the exposure time notified by the camera 12.

[0219] Time T4 represents the time between the signal IGBT being turned on and the signal IGBT being turned off.

[0220] The external flash 13 determines the timing point tm2 of the front curtain timing 71G based on the synchronization signal XON and the margin time Tmg. Since time T2 is a fixed time, the timing of the signal TRIG indicating the start of illumination is defined based on the timing when the IGBT signal is turned on.

[0221] Therefore, in activation Figure 12 In the case of fully synchronous control as shown in the diagram, the control unit 69 only needs to set the time T1 to ensure that the TRIG signal is turned on immediately after the front curtain timing 71G, so that the light can start to shine.

[0222] Figure 13 The diagram illustrates the extraction of patterns from the flash emission waveform 70 that correspond to the time interval T3 from the start of exposure (front curtain timing 71G) to the end of exposure (rear curtain timing 72G). This control is called semi-synchronous control.

[0223] In this scenario, during flash emission, only the temporally extracted interval (the shaded area in the diagram) contributes to the effective light output. Effective light output is the light output that contributes to the exposure.

[0224] This mode is thought to be possible when the camera 12 has a short exposure time (relatively high shutter speed) or a large flash output.

[0225] When semi-synchronous control is enabled, it helps the light output of the exposure to meet the required light output.

[0226] The external flash 13 can determine the time point tm2 of the front curtain timing 71G based on the sync signal XON and the margin time Tmg. Furthermore, the time point tm5 of the rear curtain timing 72G can be determined based on the exposure time (time T3).

[0227] Therefore, the emission timing is controlled to ensure that an appropriate time interval is extracted from the emission waveform 70 according to the exposure period. As described above, since the timing of the signal TRIG indicating the start of emission is defined based on the timing of the IGBT signal being turned on, the control unit 69 controls the emission timing by appropriately setting the time T1 to ensure exposure with the desired light output.

[0228] return Figure 11The full synchronization determination in step S251 is to determine whether the flash emission waveform that matches the required light output falls within the exposure period, thereby determining whether to enable full synchronization control or semi-synchronization control.

[0229] For this determination, it is necessary to compare the exposure time obtained from camera 12 with, and similarly, the flash emission time obtained from camera 12 that matches the desired light output, in order to determine their relative magnitudes.

[0230] Therefore, it is necessary to identify the flash emission time that matches the desired light output.

[0231] Note that the flash emission time referred to here includes both the afterglow emission time and the emission delay. The afterglow emission time is the period during which the light continues to be emitted even after the IGBT signal is turned off in a controlled manner to stop the emission. The emission start delay includes delays caused by changes in physical properties due to increases in the sealing gas pressure inside the Xe tube or increases in the temperature of the Xe tube, or delays attributed to other environmental factors.

[0232] Figure 14 Diagram Explanation Figure 11 A specific example of step S251.

[0233] In step S301, the external flash lamp 13 detects the voltage of the main capacitor. As described above, the main capacitor stores the charge used by the light-emitting unit 65 for emitting light.

[0234] In step S302, the external flash lamp 13, for example, refers to a threshold table stored in the storage unit 63 to determine whether the detected main capacitor voltage is stored as a table value in the threshold table.

[0235] Figure 15 Illustrated examples of threshold tables.

[0236] The threshold table stores the exposure time for each main capacitor charge level and each desired light output threshold, enabling full synchronization control.

[0237] Note that in Figure 15 In this process, the contents of the threshold table are formatted as a table for easy description, and in fact, the table data is stored in storage unit 63 in a format suitable for implementation.

[0238] The threshold table is stored, for example, as values ​​representing the inherent characteristics of the external flash 13.

[0239] In the threshold table, the desired light output is used, derived from the following formula used to convert the light output Gno. (flash index) to a base-2 logarithm:

[0240] IV = 2 * log2(Gno.) + constant.

[0241] The fundamental aspect of this formula is the conversion of optical output Gno. to the Apex system, requiring only that the constant of the latter term is suitable for implementation.

[0242] Furthermore, the IV value derived from this formula increases by 1 with each 1 EV increase in optical output, and in order to achieve a format suitable for implementation, a coefficient can be applied to improve the resolution by 1 EV.

[0243] In this threshold table, IV is stored discretely within a predetermined range of optical output.

[0244] In addition, the threshold table stores the exposure time threshold (microseconds) for each main capacitor voltage corresponding to each IV value.

[0245] As the main capacitor voltage, discrete voltage values ​​such as 330V, 310V, ... are stored, and the exposure time threshold for each voltage value is stored corresponding to the discrete IV value.

[0246] The greater the required light output, the longer the flash duration, and the higher the exposure time threshold. The exposure time threshold includes both the afterglow duration and the delay in the start of flash emission, as described above.

[0247] The exposure time threshold is determined by referring to a threshold table, but the required light output and main capacitor voltage level are only stored as discrete values ​​in the threshold table. When using the required light output, the detected main capacitor voltage, or an unstored intermediate value, the exposure time threshold is determined by corresponding linear interpolation.

[0248] exist Figure 14 In step S302, the external flash lamp 13 determines whether the detected main capacitor voltage has been stored as a table value, and if the corresponding voltage is stored, the process proceeds to step S306. For example, if the main capacitor voltage is 310V, and 310V is stored in the threshold table, then in this case, the process proceeds to step S306.

[0249] In step S306, the external flash 13 determines whether the corresponding desired light output is stored in the table of the corresponding main capacitor voltage. For example, when the IV value of the desired light output is 10.0, this value is listed in the threshold table. In this case, the exposure time threshold is read in step S307. For example, if the detected main capacitor voltage is 310V and the IV value of the desired light output received from the camera 12 is 10.0, an exposure time threshold of 223 microseconds is retrieved from the threshold table.

[0250] If the detected main capacitor voltage is, for example, 325V, and is not stored in the threshold table, the external flash lamp 13 proceeds from step S302 to step S303, and selects two columns in the threshold table that contain voltages between the detected main capacitor voltage and the threshold voltage. For example, in Figure 15 In the example shown in the diagram, when the detected main capacitor voltage is 325V, the 330V table and the 310V table are selected.

[0251] Note that if the detected main capacitor voltage is 335V or higher, which is outside the range of the threshold table, then only linear extrapolation from 330V and 310V is required.

[0252] In step S304, the external flash lamp 13 uses the detected main capacitor voltage to generate a table column by linear interpolation between the two selected columns.

[0253] like Figure 16 As illustrated in the diagram, for example, a table for 325V is generated from tables for 330V and 310V by linear interpolation based on the ratio between distances Da and Db. Distances Da and Db represent the distances from 325V to 330V and 310V, respectively.

[0254] Next, we focus on the desired light output. In step S305, the external flash 13 determines whether the desired light output exists in the table generated by linear interpolation.

[0255] For example, when the IV value of the desired light output received from camera 12 is 10.0, such as Figure 16 As shown in the diagram, the desired light output corresponds to the 325V column. In this case, in step S307, the exposure time threshold is retrieved from the column generated by linear interpolation. For example, an exposure time threshold of 210 microseconds can be retrieved from the column generated by linear interpolation.

[0256] If the required IVF value for light output is 9.7, in step S305, it is determined that there is no corresponding value in the 325V table generated by linear interpolation. In this case, the external flash 13 proceeds to step S308 and uses the required light output to perform linear interpolation to determine the exposure time threshold.

[0257] For example, such as Figure 16 As shown in the diagram, in the 325V table, a linear interpolation is performed between the exposure time threshold of 210 microseconds for IV value "10.0" and the exposure time threshold of 190 microseconds for IV value "9.50" to calculate the exposure time threshold for IV value "9.7". Distances Dc and Dd represent the distances from the target IV value "9.7" to the upper and lower IV values, respectively.

[0258] As mentioned above, by using a threshold table, the exposure time threshold can be determined based on the current main capacitor voltage and the desired light output.

[0259] In step S309, the external flash 13 compares the exposure time threshold with the current exposure time notified by the camera 12.

[0260] Then, when the exposure time is greater than the exposure time threshold, in step S310, the external flash 13 enables full synchronization control mode. When the exposure time is not greater than the exposure time threshold, in step S311, half synchronization control mode is enabled.

[0261] By obtaining the exposure time threshold based on the main capacitor voltage and the required light output, it is possible to appropriately determine whether to enable full synchronization control or semi-synchronization control.

[0262] Return again Figure 11 When in Figure 11 In step S251, as described above, it is determined whether full synchronization control or semi-synchronization control is enabled. If full synchronization control is enabled, in step S252, the external flash 13 performs full synchronization control. That is, as referenced... Figure 12 The control unit 69 of the external flash 13 sets a time T1 to ensure that the TRIG signal is activated immediately after the front curtain timing 71G, thereby starting to emit light. Furthermore, a time T4 is set to terminate the illumination.

[0263] Then, in step S254, the external flash 13 is controlled to emit light. That is, after the synchronization signal XON is activated, the control unit 69 turns on the signal IGBT based on a set time T1, and turns on the signal TRIG after a fixed time T2 has elapsed. Furthermore, after time T4 has elapsed, the signal IGBT is turned off.

[0264] As a result, the following was achieved: Figure 12 As shown in the diagram, ensure that the flash emission waveform falls within the exposure period.

[0265] Note that under this luminescence control, it is necessary to establish a sequence in which luminescence begins after the start of exposure and ends after the luminescence is completely turned off (including afterglow); therefore, luminescence needs to begin immediately after the start of exposure.

[0266] exist Figure 11 If it is determined in step S251 that semi-synchronous control is enabled, the external flash 13 proceeds to step S253 and performs timing configuration as semi-synchronous control.

[0267] That is, the extraction timing of the emission waveform is determined based on the exposure time (or shutter speed) and the required light output reference time table, and the emission start timing is determined in consideration of the margin time Tmg.

[0268] For reference Figure 13 As described above, under semi-synchronous control, light emission begins at a predetermined time before the start of exposure.

[0269] Under this semi-synchronous control, the emission start timing (timing of the IGBT turn-on signal) is determined based on a predetermined time to ensure that the required light output matches the integrated exposure of the region (shaded area) of the emission waveform 70 within the exposure period. An example of setting time point tm1 as the reference time will be described below.

[0270] Under semi-synchronous control, the exposure start time TIS relative to the reference time (time point tm1) is determined using a time schedule. The time schedule stores the appropriate exposure start time TIS based on the main capacitor voltage and the desired light output.

[0271] Since the time T2 between the reference time tm1 and the time tm3 is fixed, and the margin time Tmg is determined, the control unit 69 can determine the appropriate time T1 by determining the exposure start time TIS (T1 = Tmg - TIS).

[0272] The control unit 69 determines time point tm3 (light emission start timing) by determining time T1 and controlling the IGBT turn-on timing (time point tm1).

[0273] That is, actively controlling the emission timing ensures that the integrated exposure of the region (shaded area) of the emission waveform 70 during the exposure period matches the required light output.

[0274] Note that the emission termination timing only needs to be any time after the rear curtain timing of 72G. The emission termination timing can be terminated quickly after the rear curtain timing of 72G to improve discharge efficiency.

[0275] Figure 17 The diagram illustrates this semi-synchronous control. Figure 11 A specific example of step S253).

[0276] exist Figure 17 In step S320, the external flash lamp 13 detects the voltage of the main capacitor.

[0277] In step S321, the external flash 13 converts the exposure time into a time value (TV) format based on the Apex system to determine TV.

[0278] In step S322, the external flash 13, for example, refers to a timetable stored in the storage unit 63 to check whether a timetable corresponding to the detected main capacitor voltage exists.

[0279] Figure 18 A diagram illustrating an example of a timetable.

[0280] The schedule stores the exposure start time relative to a certain reference time (e.g., time point tm1) under semi-synchronous control.

[0281] Multiple timetables are prepared corresponding to discrete main capacitor voltages. For example, Figure 18 The diagram illustrates some timelines corresponding to a main capacitor voltage of 330V. In addition to the above tables, timelines are also prepared, for example, in 20V increments, corresponding to the voltage of each main capacitor, such as 310V, 290V, ..., 210V.

[0282] There is a possibility that the emission waveform varies greatly depending on the main capacitor voltage, and that imaging can be performed at voltages below or equal to, for example, 330V; therefore, it is desirable to go down to the lower limit of the charging voltage level used for emission, such as about 210V, and prepare a similar schedule for each main capacitor voltage, even in a discrete manner.

[0283] Note that in Figure 18 In this process, the contents of the timetable are formatted as tables for easy description, and are actually stored in storage unit 63 as table data in a format suitable for implementation.

[0284] The timetable corresponding to each main capacitor voltage stores the exposure start time and IV value corresponding to the shutter speed (TV or exposure time) and the desired light output.

[0285] For example, in TV15 (=1 / 32768), for each light output listed at predetermined intervals starting from the maximum effective light output at the top, the exposure start time for achieving effective exposure using that light output is listed. The same applies to TV14 (=1 / 16384), TV13 (=1 / 8192), and so on.

[0286] The higher the shutter speed, that is, the shorter the exposure time, the less light output is needed for the exposure.

[0287] exist Figure 18 As shown in the diagram, shutter speed increases to the left; therefore, the maximum effective light output at the top decreases to the left.

[0288] The maximum shutter speed to be defined in the timetable should be the maximum shutter speed that guarantees performance under semi-synchronous control. The shutter speed is not necessarily the maximum shutter speed that the camera 12 can set.

[0289] Therefore, as described above, the maximum shutter speed that can be controlled by the external flash 13 can be transmitted from the external flash 13 to the camera 12 via communication to reflect the shutter speed limit or chart-based control on the camera 12 side.

[0290] Here, the timetable is prepared based on discrete capacitor voltages, and the exposure start time based on discrete shutter speeds and desired light output is also stored in the timetable; therefore, interpolation is performed when the exposure start time cannot be read directly. Figure 17 The illustrations include examples of semi-synchronous control with interpolation processing.

[0291] When in Figure 17 In step S322, if a timetable corresponding to the detected main capacitor voltage exists, the external flash lamp 13 proceeds to step S326 and refers to the corresponding timetable. For example, when the main capacitor voltage is 330V, it refers to... Figure 18 The timetable in the document.

[0292] On the other hand, when there is no timetable corresponding to the detected main capacitor voltage, the external flash lamp 13 proceeds to step S323 and refers to the timetable prepared for voltages just above the main capacitor voltage to generate a new linear interpolation table TB#1 based on the TV ratio.

[0293] Figure 19 The illustration shows an example. The following text describes an example where the main capacitor voltage detected at the start of imaging is 325V, the shutter speed is TV13.3, and IV = 8.5.

[0294] In this case, the 330V timetable is referred to as the timetable for voltages just above 325V. Then, reference is made to table TB330-14 for TV14 and table TB330-13 for TV13, corresponding to the shutter speeds adjacent to TV13.3 in the timetable. Then, as illustrated in the attached diagram, linear interpolation is performed based on distances a and b from the shutter speed (TV13.3) to tables TB330-14 and TB330-13 to generate a new linear interpolation table TB#1 corresponding to TV13.3.

[0295] Next, in Figure 17 In step S324, the external flash 13 refers to a timetable prepared for a voltage just below the main capacitor voltage to generate a new linear interpolation table TB#2 based on the TV ratio.

[0296] Figure 20The illustration shows an example. In this case, the 310V timetable is referred to as the timetable for voltages just below 325V. Then, reference is made to table TB310-14 for TV14 and table TB310-13 for TV13, which correspond to the shutter speeds adjacent to TV13.3 in the timetable. Then, as illustrated in the attached figure, linear interpolation is performed based on the distances a and b from the shutter speed (TV13.3) to tables TB310-14 and TB310-13 to generate a new linear interpolation table TB#2 corresponding to TV13.3.

[0297] Next, in Figure 17 In step S325, the external flash 13 uses the main capacitor voltage to generate a new linear interpolation table TB#3 by linear interpolation between the two newly generated linear interpolation tables TB#1 and TB#2.

[0298] Figure 21 The diagram illustrates the examples. The new linear interpolation table TB#1 corresponds to 330V and TV13.3, while the new linear interpolation table TB#2 corresponds to 310V and TV13.3.

[0299] Therefore, as illustrated in the attached diagram, a new linear interpolation table TB#3 corresponding to 325V and TV13.3 is generated based on the ratio between the distances c and d from 325V.

[0300] As a result, a timetable corresponding to the current main capacitor voltage and shutter speed (exposure time) was obtained.

[0301] Incidentally, as mentioned above, in Figure 17 If a timetable for the corresponding voltage exists in step S322, and the process proceeds to step S326, then in step S327, the external flash 13 checks whether the value of the corresponding shutter speed exists in the timetable. If the value exists, the external flash 13 proceeds directly to step S329.

[0302] When the corresponding shutter speed value does not exist, in step S328, the external flash 13 uses the table of adjacent shutter speeds to generate a new linear interpolation table TB#4, and then proceeds to step S329.

[0303] Although the new linear interpolation table TB#4 is not shown, it is in principle similar to... Figure 19 and Figure 20 Linear interpolation. For example, when the main capacitor voltage is 330V and the shutter speed is TV13.3, using... Figure 18 The tables for TV14 and TV13 in the timetable corresponding to 330V are used to generate a new linear interpolation table TB#4 for TV13.3.

[0304] exist Figure 17In step S329, the external flash 13 checks whether the corresponding desired light output exists in the table being referenced.

[0305] The table being referenced is any one of the following tables: the new linear interpolation table TB#3 generated in step S325, the table column of the corresponding shutter speed in the table referenced in step S326, and the new linear interpolation table TB#4 generated in step S328.

[0306] If the required light output value exists, the corresponding exposure start time can be read as is. Therefore, in this case, the external flash 13 proceeds from step S329 to step S331 and reads the exposure start time.

[0307] If the corresponding desired light output value does not exist in the new linear interpolation table TB#3, the external flash 13 proceeds to step S330 and performs linear interpolation using the desired light output in the table (column) to derive the exposure start time.

[0308] Will use Figure 21 The new linear interpolation table TB#3 is used to describe an example.

[0309] If IV = 8.5 corresponds to the desired light output, then the exposure start time for IV = 8.7 and IV = 8.2 is taken as the desired light output for the neighboring IV = 8.5. Then, the exposure start time for the case of IV = 8.5 is calculated by linear interpolation using distances e and f from IV = 8.5.

[0310] In the external flash 13, as described above Figure 17 In step S330 or step S331, a timetable was used to determine Figure 13 The exposure start time (TIS) is shown in the diagram.

[0311] In step S333, the external flash 13 calculates time T1 using the determined exposure start time TIS as described above, and sets the emission start timing.

[0312] In step S334, the external flash 13 calculates the exposure end time:

[0313] Exposure end time = Exposure start time + Exposure time.

[0314] Then, in step S335, the external flash 13 is set to a timing for stopping illumination after the exposure end time. That is, the IGBT signal is set to remain on for a time T4. This ensures that illumination shutdown control is performed at time point tm4.

[0315] exist Figure 11 Step S253 was performed Figure 17 After the processing in the middle, the external flash lamp 13 proceeds to step S254 and performs light emission control as a semi-synchronous control.

[0316] That is, after the synchronization signal XON is activated, the control unit 69 turns on the signal IGBT based on the time T1 set using the exposure start time TIS, and turns on the signal TRIG after a fixed time T2 has elapsed. Furthermore, the signal IGBT is turned off after time T4 has elapsed.

[0317] As a result, Figure 13 As shown in the diagram, the emission for exposure is based on the waveform of the appropriate time period extracted from the flash emission waveform.

[0318] <4. Processing according to the second embodiment>

[0319] The second embodiment will be described. Although the semi-synchronous control according to the first embodiment described above is effective, errors may occur in the effective light output if a delay occurs in the emitted light waveform for some reason. This will be described first below.

[0320] Figure 22 A diagram illustrates the following... Figure 13 The emission waveform 70, front curtain timing 71G, rear curtain timing 72G, IGBT signal, and TRIG signal are shown under semi-synchronous control. Then, the case where a delay occurs during emission is indicated by a dashed line as the delayed emission waveform 70D.

[0321] The light emission begins when the TRIG signal is turned on; however, in reality, as shown in the delayed light emission waveform 70D, there is a possibility of a delay during the light emission process. Even in this case, under semi-synchronous control, the light emission stops when the IGBT signal is turned off.

[0322] Then, the shaded area corresponds to the effective light output.

[0323] Figure 22 Diagram B illustrates the section corresponding to effective light output. As shown in the attached diagram, it corresponds to... Figure 22 Compared to the case of a light emission waveform without delay, such as the light emission waveform 70D with delay, the effective light output is reduced.

[0324] Due to changes in physical properties or environmental factors, the emitted light waveform may experience a rise time delay or premature signal rise. Consequently, errors will occur in the effective light output when delays or similar issues appear in the emitted light waveform.

[0325] Note that when the required light output is relatively large, the error in effective light output caused by the delay becomes relatively small and therefore does not cause significant problems. However, at lower light output or higher shutter speeds, the error becomes relatively large.

[0326] Figure 23 A diagram illustrates an example of a situation requiring low light output. In the case of a delayed emission waveform 70D as shown in the attached diagram, the effective light output is as follows, compared to the case without delay: Figure 23 As shown in diagram B. Figure 22 The comparison of B shows that the error in effective light output becomes relatively large.

[0327] Therefore, in the second embodiment, further improvements to the semi-synchronous control will be described to prevent, for example... Figure 23 The example of a large error is shown in diagram B.

[0328] Here, we will describe how to control the light output of the Xe tube in the light-emitting unit 65.

[0329] The basic control methods used to control the light output of Xe tubes include hardware control based on light intensity feedback and software control.

[0330] Hardware control based on light intensity feedback is one of them. Figure 2 After the light-emitting unit 65 starts emitting light, when the light intensity received by the light-receiving unit 68 reaches a specified level, a control method is used to output a signal to the light-emitting control unit 64 to stop emitting light through hardware processing.

[0331] like Figure 24 As shown in Figure A, after emitting light by the TRIG signal, the emitting light is terminated at a timed interval based on the STOP signal for stopping the emitting light, which is based on feedback from the light sensor.

[0332] Software control is a control method in which the time from the start of emitting light to reaching a predetermined light intensity is pre-derived from a light intensity-timetable maintained in the flash, and the emitting light is terminated by software when said time has elapsed. For example... Figure 24 As shown in diagram B, after the LED light emission is initiated by the TRIG signal, the emission stops when the IGBT signal is turned off.

[0333] Since the light emission is stopped immediately after exposure by software, this control method is similar to the semi-synchronous control described above.

[0334] In the second embodiment, the semi-synchronous control according to the first embodiment is further divided into several cases, and hardware control is enabled when the influence of the error caused by the light emission delay increases.

[0335] This will refer to Figure 25Use A and B to describe it.

[0336] Figure 25 A diagram illustrates semi-synchronous control A. This semi-synchronous control A corresponds to the semi-synchronous control described in the first embodiment. In this case, using... Figure 18 The timetable (semi-synchronous emission extraction reference table) in the table is used to control the exposure start time (TIS).

[0337] Figure 25 Diagram B illustrates the semi-synchronous control. This semi-synchronous control B corresponds to the control method used in the second embodiment.

[0338] In the second embodiment, when the shutter speed is high and the required light output is low, a switch is made from semi-synchronous control A to semi-synchronous control B.

[0339] Under semi-synchronous control B, according to the following description Figure 31 The estimated low-emission stop schedule in the image determines the exposure start time TIS2. Emission is stopped by hardware control based on light intensity feedback. That is, Figure 2 The light-emitting control unit 64 receives light intensity feedback from the light-receiving unit 68 and terminates the light emission process when a predetermined light intensity has been accumulated.

[0340] Note that under semi-synchronous control B, the IGBT signal is turned off at a sufficiently late time to prevent the light emission from being stopped by the IGBT signal.

[0341] exist Figure 25 In B, the solid line indicates the non-delayed emission waveform 70, while the dashed line indicates the delayed emission waveform 70D.

[0342] The emission stop timing is set earlier than the rear curtain timing 72G. For example, in the emission waveform 70 shown by the solid line, the emission stops approximately at the midpoint between the front curtain timing 71G and the rear curtain timing 72G. In other words, the exposure start timing and exposure end timing are determined to ensure that the estimated emission stop time is at the midpoint of the exposure period. The exposure start time TIS2 is determined using the estimated low emission stop time schedule to achieve this timing.

[0343] Then, even if a delay occurs, the error in effective light output due to its effect will be minimized. This is because light emission stops when the light output reaches a predetermined value, and when a delay occurs during emission, as shown by the dashed line, the timing of stopping emission is also delayed. Furthermore, residual light after emission stops is also included in the effective light output.

[0344] Therefore, as Figure 25 As shown in the diagram in C, compared with the delay-free semi-synchronous control A, the effective optical output under semi-synchronous control B remains almost unchanged regardless of the presence of delay.

[0345] That is, it can ensure robustness to changes in the rise time of the emission waveform.

[0346] Note that for this type of semi-synchronous control B, the actual optical output to be set needs to be greater than the required effective optical output. This is because a portion of the actual optical output needs to be extracted.

[0347] In the following text, a specific processing example according to the second embodiment will be described.

[0348] Note that the second embodiment is similarly performed. Figure 8 and Figure 9 Examples of camera 12-side processing and Figure 10 , Figure 11 and Figure 14 An example of processing on the external flash 13 side. In the second embodiment, semi-synchronous control is as follows: Figure 26 , Figure 28 and Figure 29 As shown in the diagram.

[0349] External flash 13 Figure 11 The process proceeds to step S253 under the main light emission control, and proceeds with semi-synchronous control enabled. Figure 26 The processing in the process.

[0350] First, in step S400, the external flash 13 refers to the maximum effective light output table to determine the maximum effective light output. In this case, the maximum effective light output corresponds to the maximum effective light output achieved by the corresponding main capacitor charging voltage and the specified shutter speed (exposure period), and is used to determine whether the emission is high-speed low-light emission.

[0351] Figure 27 A diagram illustrating an example of a maximum effective light output table.

[0352] The table of maximum effective light output lists the effective light output corresponding to the main capacitor charging voltage and shutter speed (and TV value). Therefore, the maximum effective light output can be determined based on the current main capacitor charging voltage and shutter speed.

[0353] Note that if the data corresponding to the current main capacitor voltage is not available in the maximum effective light output table, linear interpolation is performed to determine the maximum effective light output corresponding to the shutter speed.

[0354] In step S401, the external flash 13 determines whether to perform semi-synchronization control B. To do this, it determines whether the following conditions are met: (Desired light output) > (Maximum effective light output) - (Predetermined light output).

[0355] That is, whether the required light output exceeds the light output obtained by subtracting the predetermined light output from the maximum effective light output achieved by the corresponding main capacitor voltage and the specified shutter speed.

[0356] If a positive result is obtained, in step S402, the external flash 13 performs semi-synchronization control A. That is, it performs... Figure 17 Semi-synchronous control in the process.

[0357] On the other hand, if no positive result is obtained in step S401, the external flash lamp 13 proceeds to step S403 to perform semi-synchronous control B.

[0358] Figure 28 and Figure 29 The diagram illustrates an example of the semi-synchronous control B process performed in step S403. Note that "C1" indicates the process from... Figures 28 to 29 The connection is processed.

[0359] exist Figure 28 In step S420, the external flash 13 detects the main capacitor voltage. Note that at this point, the main capacitor voltage has already been detected, so the stored main capacitor voltage is retrieved as a processing parameter.

[0360] In step S421, the external flash 13 converts the exposure time to the TV format based on the Apex system to determine the TV.

[0361] In step S422, the external flash lamp 13 checks, for example, whether there is a table corresponding to the current main capacitor voltage, as an actual light output table for high-speed low-emission stored in the storage unit 63.

[0362] Figure 30 The illustration shows an example of a practical light output meter used for high-speed, low-emission applications.

[0363] The actual light output table for high-speed, low-emission applications stores the actual light output (IV) for high-speed, low-emission applications in a matrix of required light output and shutter speed (TV value).

[0364] Multiple actual optical output tables for high-speed, low-emission applications are prepared corresponding to the discrete main capacitor voltages. For example, Figure 30 The diagram illustrates an example of a table where the voltage of each main capacitor is represented in increments of 20V, starting from 330V, such as 310V, 290V, ... and 210V.

[0365] Note that in Figure 30 In this process, the contents of the actual light output table used for high-speed low-emission are formatted as a table for easy description, and are actually stored in storage unit 63 as table data in a format suitable for implementation.

[0366] Here, the actual light output table for high-speed, low-emission applications is prepared based on discrete capacitor voltages, and the exposure start time based on discrete shutter speeds and the required light output is also stored in the actual light output table for high-speed, low-emission applications; therefore, interpolation is performed when the exposure start time cannot be read directly.

[0367] When in Figure 28 In step S422, if an actual light output table for high-speed low-emission lighting exists corresponding to the detected main capacitor voltage, the external flash lamp 13 proceeds to step S426 and refers to the corresponding actual light output table for high-speed low-emission lighting. For example, when the main capacitor voltage is 330V, such as... Figure 30 As shown in the diagram, there is a corresponding table, and this table can be referenced.

[0368] On the other hand, when no actual light output table for high-speed low emission corresponding to the detected main capacitor voltage does exist, the external flash lamp 13 proceeds to step S423 and, referring to the actual light output table for high-speed low emission prepared for a voltage just above the main capacitor voltage, generates a new linear interpolation table TB#21 based on the TV ratio. This is based on the reference above. Figure 19 The generation of a new linear interpolation table TB#1, which describes the time schedule, is similar to the processing of this concept.

[0369] Next, in Figure 28 In step S424, the external flash 13 refers to the actual light output table for high-speed low-emission, prepared for a voltage just below the main capacitor voltage, to generate a new linear interpolation table TB#22 based on the TV ratio.

[0370] This is also based on the above reference. Figure 20 The generation of a new linear interpolation table TB#2, which describes the time schedule, is similar to the processing of this concept.

[0371] Next, in Figure 28 In step S425, the external flash 13 uses the main capacitor voltage to generate a new linear interpolation table TB#23 by linear interpolation between the two newly generated linear interpolation tables TB#21 and TB#22. This is based on the reference... Figure 21 The new linear interpolation table TB#3 describes a similar concept for handling.

[0372] As a result, a table of actual light output for high-speed, low-light conditions was obtained, corresponding to the current main capacitor voltage and shutter speed (exposure time).

[0373] exist Figure 28 In step S429, the external flash 13 checks whether the required light output exists in the referenced table.

[0374] The referenced table is either the new linear interpolation table TB#23 generated in step S425, or the actual light output table for high-speed low-emission applications referenced in step S426.

[0375] If the corresponding desired light output value exists in these tables, the corresponding actual light output for high-speed low emission (IV) can be read as is. Therefore, in this case, the external flash 13 proceeds from step S429 to step S431 and reads the actual light output for high-speed low emission.

[0376] If the corresponding desired light output value does not exist in the new linear interpolation table TB#23, the external flash lamp 13 proceeds to step S430 and performs linear interpolation using the desired light output in the table to derive the actual light output for high-speed, low-emission applications.

[0377] In the external flash 13, as described above Figure 28 The actual light output for high-speed, low-emission applications has been determined in step S430 or step S431.

[0378] Subsequently, external flash 13 proceeded to Figure 29 Step S440. In step S440, the external flash 13 checks whether the corresponding main capacitor charging voltage is present in the estimated low light-stop schedule.

[0379] Figure 31 An example of an estimated low emission stop schedule is shown. This estimated low emission stop schedule indicates the estimated emission stop time for each main capacitor voltage relative to the actual optical output IV.

[0380] The main capacitor voltage is stored as discrete information, such as from 330V to 210V.

[0381] In step S440, it is checked whether the information corresponding to the current main capacitor voltage is stored in the estimated low-light stop schedule. If the corresponding information is stored, the external flash 13 proceeds to step S442. If the corresponding information is not stored, the external flash 13 proceeds to step S441 and generates a new linear interpolation table TB#24.

[0382] That is, the external flash 13 uses information about voltage values ​​above or below the current main capacitor voltage from the estimated low light-emitting stop time table to perform linear interpolation in order to generate a new linear interpolation table TB#24 that includes the estimated light-emitting stop time for each actual light output IV corresponding to the current main capacitor voltage.

[0383] In step S442, the external flash lamp 13 checks whether there is a corresponding actual light output as information about the current main capacitor voltage.

[0384] That is, given that information about the corresponding main capacitor voltage already exists, determine whether the corresponding actual light output value is stored in the original estimated low emission stop schedule or the new linear interpolation table TB#24.

[0385] The corresponding actual light output is the actual light output IV that corresponds to the actual light output for high-speed low light emission obtained in step S430 or step S431.

[0386] When a corresponding actual light output exists, in step S444, the external flash lamp 13 retrieves the corresponding estimated light emission stop time from the estimated low light emission stop time table or the new linear interpolation table TB#24.

[0387] When there is no corresponding actual light output, in step S443, the external flash lamp 13 uses the estimated low light emission stop time table or the new linear interpolation table TB#24 and the actual light output adjacent to the actual light output used for high-speed low light emission to perform linear interpolation to derive the estimated light emission stop time.

[0388] In step S443 or S444 above, the external flash lamp 13 has obtained the estimated light emission stop time.

[0389] In step S445, the external flash 13 calculates the exposure start time as follows:

[0390] (Exposure start time) = (Estimated luminescence stop time) - (Exposure duration / 2)

[0391] Then, in step S446, light output control is performed based on the actual light output for high-speed, low-emission applications.

[0392] The exposure start time is determined in step S445. Figure 25 The exposure start time TIS2 in B.

[0393] Due to the time between the IGBT turn-on timing and the TRIG turn-on timing ( Figure 12 and Figure 13 The time T2 is fixed, therefore the external flash 13 can use the defined exposure start time TIS to calculate time T1 (see [reference]). Figure 12 and Figure 13 ), and set the timer for the light to start.

[0394] Then, as described above, the emission is terminated by hardware control based on the feedback light intensity from the light-receiving unit 68.

[0395] <5. Operation of a multi-lamp system>

[0396] The processing under full synchronization control and semi-synchronous control described in the first embodiment, and the processing under full synchronization control, semi-synchronous control A and semi-synchronous control B described in the second embodiment, are performed not only in external flash 13A, but also in external flash 13B.

[0397] In reference Figure 1 and Figure 2 In the case of the described multi-lamp system, the desired light output, exposure time (shutter speed), margin time Tmg, and sync signal XON received from camera 12 are also transmitted from external flash 13A to external flash 13B via wireless communication units 66A and 66B.

[0398] This configuration even allows each external flash unit 13B, positioned in a spatially separated location, to actively determine the timing for the start of flash emission.

[0399] The light-emitting instructions can be distributed according to a ratio set for each group and directed to the external flashlight 13B, which acts as the receiver.

[0400] <6. Conclusions and Variations>

[0401] According to the above embodiments, the following effects can be obtained.

[0402] The external flash unit 13 (13A, 13B) according to the first and second embodiments includes a light-emitting unit 65, a communication unit 67, and a control unit (69, 64). The communication unit 67 receives desired light output and exposure time information specified by the camera 12, as well as a synchronization signal XON for synchronizing the exposure timing and light-emitting timing of the camera 12. The control unit (69, 64) determines the light-emitting start timing of the light-emitting unit 65 based on the desired light output and exposure time information, and causes the light-emitting unit 65 to flash at the determined light-emitting start timing.

[0403] That is, when the external flash 13 emits light synchronously with the shutter release of the camera 12, the timing of the light emission start is actively controlled to ensure that the external flash 13 emits light to achieve the required light output received from the camera 12 according to the exposure period of the camera 12.

[0404] Therefore, flash can be used even when the shutter speed (exposure time) exceeds the so-called sync speed. In other words, flat flash is not required when exceeding the sync speed, which eliminates the disadvantages of flat flash and achieves efficient flash operation.

[0405] Note that the required light output is the information about the light output sent by camera 12 in order to properly capture an image of the subject. Exposure time information can be any information that determines the exposure time used for the current imaging. For example, exposure time information can be the exposure time value itself, or a shutter speed value that can be used to calculate the exposure time.

[0406] In the external flash 13 according to the first and second embodiments, an example is described in which the control unit 69 performs a determination process based on the desired light output and exposure time information, selecting full-synchronization control to ensure that the light emission begins after the start of the exposure period, or semi-synchronization control to ensure that the exposure period coincides with a portion of the light emission waveform, and controls the light emission operation of the light-emitting unit 65 to be either full-synchronization control or semi-synchronization control (see [link]). Figure 11 ).

[0407] The control method is selected based on the length of the exposure period. If the exposure period is sufficiently long compared to the flash emission period, full synchronization control is only required for emission at a speed below the sync speed. In this case, only the emission timing needs to be determined to ensure that exposure begins before the emission starts.

[0408] The exposure period is shorter than the flash emission period, and semi-synchronous control is performed as emission at a so-called sync speed or higher. In this case, control is performed to determine the emission timing, thereby ensuring that the exposure period coincides with a portion of the emission waveform, enabling emission that contributes to the desired light output.

[0409] In the first embodiment, an example is described in which the control unit 69 performs a process of determining an exposure time threshold corresponding to the voltage value of the main capacitor storing charge for emitting light, which is received by the communication unit 67, and comparing the exposure time threshold with the exposure time indicated by the exposure time information received by the communication unit 67, as a determination process for full synchronization control and semi-synchronization control. Figure 11 Step S251).

[0410] This allows for the appropriate determination of the conditions for semi-synchronous control. That is, the exposure time threshold, which serves as the dividing line between semi-synchronous and full-synchronous control, is appropriately selected based on the desired light output and capacitor voltage.

[0411] The external flash 13 according to an embodiment includes a storage unit 63 storing a threshold table containing exposure time thresholds corresponding to the desired light output and the voltage values ​​of capacitors storing charge for light emission. An example is then described in which, as a decision-making process for full-synchronization and semi-synchronization control, the control unit 69 performs a process of using the threshold table to determine the exposure time thresholds corresponding to the desired light output and the voltage values ​​of the main capacitor, and comparing the determined exposure time thresholds with the exposure time indicated by the exposure time information received by the communication unit 67.

[0412] By storing this threshold table, the exposure time threshold that serves as the dividing line between semi-synchronous control and full-synchronous control can be easily obtained.

[0413] In a first embodiment, an example is described in which, when the detected voltage value of the main capacitor does not match any voltage value stored in the threshold table, the control unit 69 uses an exposure time threshold corresponding to the voltage value stored in the threshold table to perform an interpolation calculation to determine an exposure time threshold corresponding to the desired light output and the detected voltage value of the main capacitor.

[0414] By performing interpolation calculations as needed, the amount of information in the threshold table can be minimized. This reduces the capacity required to store the threshold table in the external flash 13.

[0415] In the first embodiment, under semi-synchronous control, the control unit 69 determines the exposure start time TIS corresponding to the detected voltage value of the main capacitor and the desired light output and exposure time information received by the communication unit 67. An example in which the emission start timing is determined based on the determined exposure start time TIS is then described.

[0416] Under semi-synchronous control, such as Figure 13 As illustrated in the diagram, a portion of the emission waveform is extracted to match the exposure period on camera side 12. Therefore, the exposure start time (front curtain timing time) is determined relative to a reference time (e.g., time point tm1) associated with the emission timing, based on the main capacitor voltage, desired light output, and exposure time information, and a light intensity corresponding to the desired light output is provided during the exposure period. Since the emission waveform varies depending on the main capacitor voltage, and the extraction period varies depending on the exposure time and desired light output, the emission start timing can be appropriately determined based on conditions or requirements by determining the exposure start time based on the main capacitor voltage, desired light output, and exposure time, and by controlling the emission start timing.

[0417] In one embodiment, the external flash 13 includes a storage unit 63 storing a timetable, which includes an exposure start time corresponding to the voltage value of the main capacitor storing the charge for light emission, the exposure time, and the desired light output. Under semi-synchronous control, the control unit 69 uses the timetable to determine the exposure start time TIS corresponding to the exposure time indicated by the desired light output and exposure time information received by the communication unit 67, and determines the light emission start timing based on the determined exposure start time TIS.

[0418] By storing the schedule, the appropriate exposure start time can be easily obtained.

[0419] In the first embodiment, an example is described in which, when the detected voltage value of the main capacitor does not match any voltage value stored in the timetable, the control unit 69 performs interpolation calculations using the timetable for each stored voltage value to determine the exposure start time (see [link]). Figure 17 ).

[0420] By performing interpolation calculations as needed, the amount of information in the timetable can be minimized. This reduces the capacity required to store the timetable in the external flash 13.

[0421] In this embodiment, an external flash 13 is described as acting as both a commander and a receiver. In the external flash 13B acting as a receiver, a wireless communication unit 66B receives from the external flash 13A acting as a commander information the desired light output and exposure time specified by the camera 12, as well as a synchronization signal XON.

[0422] With this configuration, in a multi-lamp system using radio or similar means, each external flash 13 can actively determine the flash start timing using a signal from a camera 12 for synchronized flashing. In this case, the shutter speed (exposure time) and the synchronization signal are included in the communication from the wireless command unit (external flash 13A) attached to the camera 12 to the receiver (external flash 13B) installed at a spatially separated location, thereby allowing both to actively determine the flash timing.

[0423] In one embodiment, an example is described in which the control unit 69 determines whether the exposure time specified by the camera 12 exceeds the corresponding exposure time limit and notifies the imaging device of the determination result.

[0424] For example, high shutter speeds (short exposure times) can be supported under semi-synchronous control, but camera 12 can notify of short exposure times (or shutter speeds) exceeding the limits of supported exposure times. That is, the timetable does not support this. Therefore, it is determined whether the permissible limit has been exceeded, and if so, the fact is notified to camera 12. Figure 10 Steps S210 and S203A).

[0425] Therefore, the maximum shutter speed and configuration limits can be set on the camera 12 side. Furthermore, by sending a notification to the user, the user can be aware that the external flash 13 has exceeded the shutter speed supported by the synchronization control.

[0426] In one embodiment, an example is described where the control unit 69 performs processing to notify the camera 12 of whether light emission corresponding to the desired light output has been achieved, or of the maximum coverage area of ​​the light emission corresponding to the desired light output. Figure 10 Step S203A).

[0427] Therefore, it is possible to display on the side of camera 12 whether the external flash 13 is ready to emit sufficient light. Figure 8 Step S104A) is used to notify the user of the status.

[0428] Note that it is also conceivable that the display unit 23 of the external flash 13 sends a notification about whether the external flash 13 is ready to emit sufficient light.

[0429] Incidentally, the camera 12 may have the function of allowing users to manually specify the illumination timing, and the exposure / light output calculation and control circuit 40 may change the illumination start timing based on the user-specified illumination timing.

[0430] For example, when the illumination timing is specified through the menu settings of camera 12, the camera changes the output timing of the exposure-based sync signal XON according to the specified timing, and instructs the external flash 13 to flash at the timing of the sync signal XON. Upon receiving this instruction, the external flash 13 stops the process of determining the active illumination start timing and flashes at the timing of the sync signal XON.

[0431] Therefore, it can handle situations where users expect to specify the range to be extracted from the emitted waveform.

[0432] In the second embodiment, an example is described in which a first emission control (semi-synchronous control A) and a second emission control (semi-synchronous control B) are selectively performed as semi-synchronous control. Under semi-synchronous control A, the external flash lamp 13 determines an exposure start time TIS corresponding to the detected voltage value of the main capacitor and the desired light output and exposure time information received through the communication unit 67. Then, based on the determined exposure start time TIS, an emission start timing and an emission end timing are determined, and emission control is performed. Under semi-synchronous control B, the external flash lamp 13 determines an exposure start time TIS2 corresponding to the detected voltage value of the main capacitor and the desired light output and exposure time information received through the communication unit 67. Then, based on the exposure start time TIS2, an emission start timing is determined, emission control is performed, and emission is terminated based on the light output detected by the light receiving unit 68.

[0433] This allows light intensity feedback control to stop emitting light during high shutter speed operation and low emission periods, thus minimizing errors in effective light output even when there are delays in the emission waveform. Therefore, high-precision emission can be achieved even with time variations in the emission waveform.

[0434] In the second embodiment, either semi-synchronous control A or semi-synchronous control B is selected based on whether the required light output exceeds the light output obtained by subtracting the predetermined light output from the maximum effective light output achieved by the exposure time and the corresponding main capacitor voltage value.

[0435] Therefore, based on the relationship between the required light output, the main capacitor voltage, and the exposure time, the semi-synchronous control B can be activated under appropriate conditions.

[0436] According to an embodiment, the camera 12 includes a communication unit 48, which sends the required light output, exposure time information and synchronization signal XON to an external flash 13. The external flash 13 includes a control unit 69, which determines the light emission start timing of the light emission unit 65 based on the required light output and exposure time information, and causes the light emission unit 65 to flash at the determined light emission start timing.

[0437] That is, the information used to determine the timing of the start of the light emission is sent to the external flash lamp 13.

[0438] By notifying the camera 12 of the required light output and exposure time information, the external flash 13 can perform timing control of light emission when the synchronization signal XON is activated.

[0439] Furthermore, according to the embodiment of the camera 12, the communication unit 48 receives a determination result from the external flash 13 regarding whether the transmitted exposure time exceeds the corresponding exposure time limit, and the camera 12 also includes a display unit 37, which displays information indicating the received determination result. Figure 8 Step S104A).

[0440] Therefore, the user can be notified whether the external flash 13 is capable of responding.

[0441] Note that the effects described in this instruction manual are merely examples and are not limited to any particular effect; other effects may also be provided.

[0442] Note that this technology may also have the following configurations.

[0443] (1) A flash device, comprising:

[0444] Light-emitting unit;

[0445] The communication unit receives desired light output and exposure time information specified by the imaging device, as well as a synchronization signal for synchronizing the exposure timing and emission timing of the imaging device; and

[0446] The control unit determines the light emission start timing of the light-emitting unit based on the required light output and exposure time information, and causes the light-emitting unit to flash light at the determined light emission start timing.

[0447] (2) The flash device according to (1) above, wherein

[0448] Based on the required light output and exposure time information, the control unit performs a decision-making process to select between fully synchronous control that ensures the light emission begins after the exposure period starts or semi-synchronous control that ensures the exposure period is consistent with a part of the light emission waveform, and controls the light emission operation of the light-emitting unit to be either fully synchronous or semi-synchronous.

[0449] (3) The flash device according to (2) above, wherein

[0450] As part of the aforementioned determination process.

[0451] The control unit performs

[0452] The process of determining an exposure time threshold corresponding to the desired light output received by the communication unit and the voltage value of the capacitor storing charge for emitting light, and comparing the exposure time threshold with the exposure time indicated by the exposure time information received by the communication unit.

[0453] (4) The flash device according to (2) or (3) above further includes:

[0454] A storage unit stores a threshold table, which includes exposure time thresholds corresponding to the desired light output and the voltage values ​​of the capacitor storing the charge for light emission.

[0455] As part of the aforementioned determination process.

[0456] The control unit performs

[0457] The process of using the threshold table to determine an exposure time threshold corresponding to the desired light output received by the communication unit and the voltage value of the capacitor, and comparing the exposure time threshold with the exposure time indicated by the exposure time information received by the communication unit.

[0458] (5) The flash device according to (4) above, wherein

[0459] If the detected voltage value of the capacitor does not match any voltage value stored in the threshold table,

[0460] The control unit performs an interpolation calculation using an exposure time threshold corresponding to a voltage value stored in the threshold table to determine the exposure time threshold.

[0461] (6) The flash device according to any one of (2) to (5) above, wherein

[0462] Under the semi-synchronous control,

[0463] The control unit determines

[0464] The exposure start time is relative to the reference time associated with the light emission timing. The exposure start time corresponds to the voltage value of the capacitor storing the charge for light emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit, and the light emission start timing is determined based on the exposure start time.

[0465] (7) The flash device according to any one of (2) to (6) above, further comprising:

[0466] A storage unit stores a time schedule, which corresponds to the voltage value of a capacitor storing charge for light emission, the exposure time, and the desired light output, including the exposure start time.

[0467] Under the semi-synchronous control,

[0468] The control unit

[0469] The timetable is used to determine the exposure start time relative to a reference time associated with the emission timing. The exposure start time corresponds to the voltage value of the capacitor storing the charge for emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit. The emission start timing is determined based on the determined exposure start time.

[0470] (8) The flash device according to (7) above, wherein

[0471] If the detected voltage value of the capacitor does not match any voltage value stored in the time schedule,

[0472] The control unit performs interpolation calculations using the timetable for each stored voltage value to determine the exposure start time.

[0473] (9) The flash device according to any one of (1) to (8) above, wherein

[0474] The communication unit receives the desired light output and exposure time information, as well as a synchronization signal, specified by the imaging device, from another flash device that acts as a command device.

[0475] (10) The flash device according to any one of (1) to (9) above, wherein

[0476] The control unit determines whether the exposure time specified by the imaging device exceeds the corresponding exposure time limit, and notifies the imaging device of the determination result.

[0477] (11) The flash device according to any one of (1) to (10) above, wherein

[0478] The control unit processes the following: notifies the imaging device of whether light emission corresponding to the desired light output has been achieved, or information about the maximum coverage area of ​​light emission corresponding to the desired light output, or displays the information on the display unit.

[0479] (12) The flash device according to (2) above, wherein

[0480] Under the semi-synchronous control,

[0481] The control unit selectively performs

[0482] A first light emission control is used to determine an exposure start time relative to a reference time associated with light emission timing. This exposure start time corresponds to the voltage value of a capacitor storing charge for light emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit. Based on this exposure start time, a light emission start timing and a light emission end timing are determined.

[0483] The second light emission control is used to determine an exposure start time relative to a reference time associated with the light emission timing. The exposure start time corresponds to the voltage value of a capacitor storing charge for light emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit. The light emission start timing is determined based on the exposure start time, and light emission control is performed to terminate light emission based on the detected light output.

[0484] (13) The flash device according to (12) above, wherein

[0485] The control unit

[0486] Based on whether the required light output exceeds the light output obtained by subtracting the predetermined light output from the maximum effective light output achieved by the exposure time and the corresponding voltage of the capacitor, a first light emission control or a second light emission control is selected.

[0487] (14) An imaging device, comprising:

[0488] The communication unit sends the required light output, exposure time information, and synchronization signal to the flash device. The synchronization signal is used to synchronize the exposure timing and the emission timing. The flash device includes a control unit, which determines the emission start timing of the emission unit based on the required light output and exposure time information and the synchronization signal, and causes the emission unit to emit light at the determined emission start timing.

[0489] (15) The imaging device according to (14) above, wherein

[0490] The communication unit receives from the flash device a determination result regarding whether the transmitted exposure time exceeds the corresponding exposure time limit.

[0491] The imaging device also includes a display unit that displays information indicating the received judgment results.

[0492] (16) The imaging device according to (14) or (15) above further includes:

[0493] Allows users to manually adjust the timing configuration of the light emission;

[0494] Based on the configuration made through the aforementioned configuration function, the function adjusts the output timing of the exposure of the signal initiating the illumination command; and

[0495] The instruction specifies that the flashing device should emit light at a timed synchronization with the signal.

[0496] (17) The flash device according to any one of (1) to (13) above, wherein

[0497] The imaging device includes: a configuration function that allows the user to manually adjust the emission timing; a function that adjusts the output timing of the exposure of the signal instructing the emission to begin based on the configuration made through the configuration function; and a function that instructs the flash device to emit a flash at a timing synchronized with the signal.

[0498] In response to a command from the imaging device, the process of actively determining the timing of the emission start is disabled, and flash emission is performed at a timing synchronized with the signal.

[0499] (18) A method for controlling light emission, comprising:

[0500] Controlling a flashing device, the flashing device comprising a light-emitting unit, a communication unit, and a control unit:

[0501] The communication unit receives the desired light output and exposure time information specified by the imaging device, as well as a synchronization signal for synchronizing the exposure timing and emission timing of the imaging device; and

[0502] The control unit determines the light emission start timing of the light-emitting unit based on the synchronization signal, based on the required light output and exposure time information, and causes the light-emitting unit to flash light at the determined light emission start timing.

[0503] List of reference numerals

[0504] 11 Imaging System

[0505] 12 Cameras

[0506] 13, 13A, 13B-1, 13B-2 External Flash Units

[0507] 21 display units

[0508] 22 Operation Units

[0509] Display units 23, 23A, 23B-1, 23B-2

[0510] 24, 24A, 24B-1, 24B-2 operating units

[0511] 40 Exposure / Light Output Calculation and Control Circuit

[0512] 41 Focusing on computational and control circuits

[0513] 42 Operation Units

[0514] 43 Control Unit

[0515] 48 Communication Units

[0516] 62, 62A, 62B Display Control Unit

[0517] 63, 63A, 63B memory cells

[0518] 64, 64A, 64B Light Emitting Control Unit

[0519] 65, 65A, 65B light-emitting units

[0520] 66, 66A, 66B wireless communication units

[0521] 67, 67A, 67B communication units

[0522] 68, 68A, 68B light-receiving units

[0523] 69, 69A, 69B control units

Claims

1. A flash device, comprising: Light-emitting unit; The communication unit receives the desired light output and exposure time information specified by the imaging device, as well as a synchronization signal for synchronizing the exposure timing and emission timing of the imaging device. and The control unit determines the light emission start timing of the light-emitting unit based on the required light output and exposure time information, and causes the light-emitting unit to flash light at the determined light emission start timing.

2. The flash device according to claim 1, wherein... Based on the required light output and exposure time information, the control unit performs a decision-making process to select between fully synchronous control that ensures the light emission begins after the exposure period starts or semi-synchronous control that ensures the exposure period is consistent with a part of the light emission waveform, and controls the light emission operation of the light-emitting unit to be either fully synchronous or semi-synchronous.

3. The flash device according to claim 2, wherein... As part of the aforementioned determination process. The control unit performs The process of determining an exposure time threshold corresponding to the desired light output received by the communication unit and the voltage value of the capacitor storing charge for emitting light, and comparing the exposure time threshold with the exposure time indicated by the exposure time information received by the communication unit.

4. The flash device according to claim 2, further comprising: A storage unit stores a threshold table, which includes exposure time thresholds corresponding to the desired light output and the voltage values ​​of the capacitor storing the charge for light emission. As part of the aforementioned determination process. The control unit performs The process of using the threshold table to determine an exposure time threshold corresponding to the desired light output received by the communication unit and the voltage value of the capacitor, and comparing the exposure time threshold with the exposure time indicated by the exposure time information received by the communication unit.

5. The flash device according to claim 4, wherein If the detected voltage value of the capacitor does not match any voltage value stored in the threshold table, The control unit performs an interpolation calculation using an exposure time threshold corresponding to a voltage value stored in the threshold table to determine the exposure time threshold.

6. The flash device according to claim 2, wherein Under the semi-synchronous control, The control unit determines The exposure start time is relative to the reference time associated with the light emission timing. The exposure start time corresponds to the voltage value of the capacitor storing the charge for light emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit, and the light emission start timing is determined based on the exposure start time.

7. The flash device according to claim 2, further comprising: A storage unit stores a time schedule, which corresponds to the voltage value of a capacitor storing charge for light emission, the exposure time, and the desired light output, including the exposure start time. Under the semi-synchronous control, The control unit The timetable is used to determine the exposure start time relative to a reference time associated with the emission timing. The exposure start time corresponds to the voltage value of the capacitor storing the charge for emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit. The emission start timing is determined based on the determined exposure start time.

8. The flash device according to claim 7, wherein If the detected voltage value of the capacitor does not match any voltage value stored in the time schedule, The control unit performs interpolation calculations using the time schedule for each stored voltage value to determine the exposure start time.

9. The flash device according to claim 1, wherein The communication unit receives the desired light output and exposure time information, as well as a synchronization signal, specified by the imaging device, from another flash device that acts as a command device.

10. The flash device according to claim 1, wherein The control unit determines whether the exposure time specified by the imaging device exceeds the corresponding exposure time limit, and notifies the imaging device of the determination result.

11. The flash device according to claim 1, wherein The control unit processes the following: notifies the imaging device of whether light emission corresponding to the desired light output has been achieved, or information about the maximum coverage area of ​​light emission corresponding to the desired light output, or displays the information on the display unit.

12. The flash device according to claim 2, wherein Under the semi-synchronous control, The control unit selectively performs A first light emission control is used to determine an exposure start time relative to a reference time associated with light emission timing. This exposure start time corresponds to the voltage value of a capacitor storing charge for light emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit. Based on this exposure start time, a light emission start timing and a light emission end timing are determined. The second light emission control is used to determine an exposure start time relative to a reference time associated with the light emission timing. The exposure start time corresponds to the voltage value of a capacitor storing charge for light emission, the desired light output received by the communication unit, and the exposure time indicated by the exposure time information received by the communication unit. The light emission start timing is determined based on the exposure start time, and light emission control is performed to terminate light emission based on the detected light output.

13. The flash device according to claim 12, wherein The control unit Based on whether the required light output exceeds the light output obtained by subtracting the predetermined light output from the maximum effective light output achieved by the exposure time and the corresponding voltage of the capacitor, a first light emission control or a second light emission control is selected.

14. An imaging device, comprising: The communication unit sends the required light output, exposure time information, and synchronization signal to the flash device. The synchronization signal is used to synchronize the exposure timing and the emission timing. The flash device includes a control unit, which determines the emission start timing of the emission unit based on the required light output and exposure time information and the synchronization signal, and causes the emission unit to emit light at the determined emission start timing.

15. The imaging apparatus according to claim 14, wherein The communication unit receives from the flash device a determination result regarding whether the transmitted exposure time exceeds the corresponding exposure time limit. The imaging device also includes a display unit that displays information indicating the received judgment results.

16. The imaging device according to claim 14, further comprising: Allows users to manually adjust the timing configuration of the light emission; Based on the configuration made through the aforementioned configuration function, the function adjusts the output timing of the exposure of the signal initiating the illumination command; and The instruction specifies that the flashing device should emit light at a timed synchronization with the signal.

17. The flash device according to claim 1, wherein The imaging device includes: The system includes a configuration function that allows the user to manually adjust the emission timing; a function to adjust the output timing of the signal instructing the emission to begin based on the configuration made through the configuration function; and a function to instruct the flash device to emit a flash at a timing synchronized with the signal. In response to a command from the imaging device, the process of actively determining the timing of the emission start is disabled, and flash emission is performed at a timing synchronized with the signal.

18. A method for controlling light emission, comprising: Controlling the flashing device, the flashing device includes a light-emitting unit, a communication unit, and a control unit: The communication unit receives the required light output and exposure time information specified by the imaging device, as well as a synchronization signal for synchronizing the exposure timing and emission timing of the imaging device. as well as The control unit determines the light emission start timing of the light-emitting unit based on the synchronization signal, based on the required light output and exposure time information, and causes the light-emitting unit to flash light at the determined light emission start timing.

Images