JP2015088838A - Imaging apparatus, imaging system, and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus that accurately implements exposure or photometry even in the case where an illumination device emits light multiple times, an imaging system and a control method.SOLUTION: When a SUB signal changes from Hi to Lo, an electronic shutter is opened, and a CCD 138 for photometry implements exposure and starts storing electric charge. Next, when a sensor gate signal becomes Hi, the CCD 138 for photometry outputs electric charge. Thus, photometric data is outputted. A period from making the SUB signal Lo to making the sensor gate signal Hi is an exposure term T4. Next, the SUB signal is made Hi. The SUB signal is then made Lo after the lapse of an imaging term T3 from making the SUB signal Lo for the first time. When the SUB signal is made Lo, the exposure term T4 is started again, the CCD 138 for photometry implements exposure, and photometric data is outputted. Imaging is then finished.

Description

  The present invention relates to an imaging apparatus, an imaging system, and a control method that control an illumination apparatus.

  There is known a flash photographing system including a plurality of flashes (illumination devices) and a lens interchangeable single-lens reflex camera. In order to cause the plurality of flashes (lighting devices) to emit light sequentially, the camera determines whether the next light emission is the first or second time, determines a period for performing photometry, and transmits a light emission start signal to each of the plurality of flashes. A plurality of flashes emit light when a light emission start signal is received, and the camera performs photometry (Patent Document 1).

JP-A-60-195534

  However, some flashes have a predetermined light emission interval and cannot be changed. Further, when imaging is repeated using the imaging device, the imaging interval cannot be set to a predetermined value or less due to the performance of the imaging device. When imaging is repeated using such a flash and an image sensor, the exposure period of the image sensor deviates from the light emission period of the flash, and the subject image may not be accurately exposed or metered.

  The present invention has been made in view of these problems, and it is possible to obtain an imaging apparatus, an imaging system, and a control method that accurately perform exposure or photometry even when the illumination apparatus emits light multiple times. Objective.

  The imaging device according to the first aspect of the present invention is an imaging device that is used together with an illumination device that emits light a predetermined number of times of light emission at a predetermined light emission period (T2), and when the illumination device emits illumination light. A light emission control unit that controls the illumination light, and an imaging element that captures the reflected light generated by reflecting the illumination light on the subject for a predetermined number of times of imaging with a predetermined imaging cycle (T3) equal to the predetermined number of times of light emission. Is before the time when the first imaging is started among the predetermined number of times of imaging, and after the time when the last imaging is finished among the predetermined number of times of imaging so as to start the first light emission among the predetermined number of times of light emission. The lighting device is controlled so that the final light emission is completed within a predetermined number of light emission times.

  The imaging apparatus preferably includes an electronic shutter, and the electronic shutter is preferably closed until at least the current light emission ends after the imaging apparatus ends the current imaging. It can be prevented that the current light emission period is covered in the next exposure period and the current light emission affects the next exposure.

  The illumination device emits light for a predetermined light emission period (T1) per light emission, the imaging element performs exposure for a predetermined exposure period (T4) per image pickup, and the light emission control unit When the imaging period is longer than the light emission period, it is preferable to control the first light emission timing so that the exposure period is included in the light emission period in all the light emission times. Each light emission period can reliably include each exposure period.

  The light emission control unit controls the lighting device such that a period between a time when the first imaging is started out of the predetermined number of times and a time when the first light emission is started out of the predetermined number of times is equal to or longer than the first unstable period. It is preferable to control. It is possible to prevent photometry under unstable light quantity.

  The light emission control unit performs illumination so that a period between a time when the last imaging is finished out of the predetermined number of times and a time when the last light emission is finished among the predetermined times is equal to or longer than the second unstable period. It is preferable to control the apparatus. It is possible to prevent photometry under unstable light quantity.

  The imaging period (T3) is preferably longer than the light emission period (T2).

  There are a plurality of illumination devices, and each illumination device preferably emits light once at a predetermined light emission period (T2).

  It is preferable that the image processing device further includes a signal processing unit, the imaging device captures reflected light and outputs imaging data, and the signal processing unit determines exposure using the imaging data.

  An imaging system according to a second invention of the present application includes the imaging device and a lighting device.

  The control method according to the third invention of the present application provides a predetermined light emission according to a process of imaging the reflected light generated by the reflection of the illumination light on the subject at a predetermined imaging cycle (T3) twice or more times. A method of controlling a lighting device that emits light for a predetermined number of times of light emission that is equal to a predetermined number of times of imaging in a period (T2), the step of detecting a final imaging end time at which the final imaging of the predetermined number of imaging times ends, A step of determining a final light emission end timing at which the last light emission ends among the predetermined number of times of light emission after a time when the imaging is completed; a step of detecting an initial imaging start time at which the first imaging starts within the predetermined number of times of imaging; Before the first imaging start timing, a step of determining a first light emission start time at which the first light emission starts out of a predetermined number of times of light emission, and a final light emission end time and an initial light emission start time according to the lighting device Characterized in that it comprises a step of controlling the light period.

  According to the present invention, an imaging device, an imaging system, and a control method that accurately perform exposure or photometry are obtained even when the illumination device emits light multiple times.

1 is a block diagram schematically illustrating an imaging apparatus according to an embodiment. It is the block diagram which showed the imaging device and the illuminating device schematically. It is the timing chart which showed the comparative example of the light emission control processing. It is a timing chart showing light emission control processing.

  Hereinafter, an imaging system 100 according to an embodiment of the present invention will be described with reference to the drawings. First, the configuration of the imaging system 100 will be described with reference to FIG.

  The imaging system 100 includes a digital camera 110 that is an imaging device, and a first flash 201 and a second flash 202 that are illumination devices.

  The digital camera 110 mainly includes an imaging lens 120 and a camera body 130.

  The imaging lens 120 includes a zoom lens 121, a diaphragm blade 122, and a focusing lens 123. The zoom lens 121 moves back and forth on the optical axis to change the angle of view of the imaging lens 120. The aperture blade 122 is driven by an aperture blade motor 136 described later to open and close. The focusing lens 123 is driven by a focusing motor 135, which will be described later, and moves forward and backward along the optical axis, thereby forming a subject image on an imaging CCD 131, which will be described later.

  The camera body 130 includes an imaging CCD 131, a shutter curtain 132, a return mirror 133, an AF sensor 134, a focusing motor 135, an aperture blade motor 136, an auxiliary LED 137, a photometric CCD 138 that is an imaging element, An eyepiece 139 and a pentaprism 140 are mainly provided.

  The imaging CCD 131 captures a subject image received through the imaging lens 120 and outputs image data.

  The shutter curtain 132 is a focal plane shutter and is driven at the time of shooting.

  The return mirror 133 is a half mirror, and is positioned on the optical path before photographing. The return mirror 133 transmits a part of the subject image toward the sub mirror 141 and reflects a part of the subject image toward the pentaprism 140. The return mirror 133 is moved to the storage position 133a during photographing. As a result, a subject image is formed on the imaging CCD 131.

  The sub mirror 141 reflects the subject image toward the AF sensor 134. The AF sensor 134 is a phase difference sensor, and determines whether or not a subject image is formed on the imaging CCD 131.

  The focusing motor 135 drives the focusing lens 123 according to the determination of the AF sensor 134.

  The diaphragm blade motor 136 drives the diaphragm blade 122 based on the value measured by the photometric CCD 138.

  The auxiliary LED 137 emits light when there is not enough light when performing autofocus. At this time, the AF sensor 134 uses the light from the auxiliary LED 137 to determine whether or not the subject image is formed on the imaging CCD 131.

  The pentaprism 140 receives the subject image from the return mirror 133, reflects it from the reflecting surfaces 140 a and 140 b, and emits the subject image toward the photometric CCD 138 and the eyepiece 139.

  The photometric CCD 138 receives reflected light generated by reflecting the illumination light on the subject through the imaging lens 120, the pentaprism 140, and the like, and outputs photometric data. In other words, the photometric CCD 138 measures the amount of light of the subject image and outputs photometric data. The photometric CCD 138 can repeatedly capture a subject image, but due to the performance of the photometric CCD 138, at least a predetermined period must be provided between the imaging. This predetermined period is called the shortest imaging cycle.

  The user observes the subject image through the eyepiece lens 139.

  The first flash 201 and the second flash 202 are connected to the digital camera 110 via the cable 204.

  Next, an electrical circuit included in the digital camera 110 will be described with reference to FIG.

  The digital camera 110 includes a photometric CCD 138, an AFE 150, a DSP 160 that constitutes a light emission control unit and a signal processing unit, an SDRAM 171, a ROM 172, and a built-in flash 203.

  The AFE 150 includes a CDS 151, an AGC 152, an A / D converter 153, and a TG 154. When the AFE 150 receives photometric data from the photometric CCD 138, the CDS 151 samples the photometric data, and the AGC 152 adjusts the gain of the sampled photometric data. The A / D converter 153 receives the photometric data from the AGC 152, converts it into digital data, and transmits the digital data to the DSP 160. The TG 154 receives a clock from the DSP 160, generates a synchronization signal, a vertical synchronization signal (VD), a SUB signal, and a sensor gate signal (SG), and sends them to the photometric CCD 138, CDS 151, AGC 152, and A / D converter 153. Send. The photometric CCD 138, CDS 151, AGC 152, and A / D converter 153 operate in accordance with the synchronization signal.

  The SUB signal is a signal that causes the photometric CCD 138 to start exposure. When the SUB signal is Hi, the photometric CCD 138 releases all accumulated charges, and when it is Lo, accumulates charges. The sensor gate signal is a signal that causes the photometric CCD 138 to end the exposure. When the sensor gate signal becomes Hi, the photometric CCD 138 outputs all accumulated charges. The SUB signal and the sensor gate signal have a so-called electronic shutter function. The electronic shutter is opened from when the SUB signal becomes Lo until the sensor gate signal becomes Hi, and the photometric CCD 138 is exposed to accumulate charges. In other periods, the electronic shutter is closed.

  The DSP 160 mainly includes a CPU block 162 and a CCD I / F 161 and is connected to the SDRAM 171 and the ROM 172. The ROM 172 stores a control program for the DSP 160, and the DSP 160 reads the control program from the ROM 172 and executes it.

  The CCD I / F 161 receives the photometric data from the AFE 150 and transmits it to the CPU block 162. The CPU block 162 receives the photometric data and stores it in the SDRAM 171.

  The CPU block 162 is connected to the first flash 201, the second flash 202, and the internal flash, and transmits a light emission signal thereto. The first flash 201, the second flash 202, and the internal flash emit light when a light emission signal is received from the CPU block 162.

  The first flash 201 and the second flash 202 can be pre-flashed. The pre-light emission is a test light emission performed before the actual photographing, and is a light emission method in which flat light emission, for example, intermittent light emission with a period of several tens Hz is performed for a predetermined light emission period.

  When pre-light emission is performed using a plurality of flashes, each flash sequentially emits flat light for a predetermined light emission period. That is, after the first flash 201 performs flat light emission only for a predetermined light emission period, the second flash 202 performs flat light emission only for a predetermined light emission period, and the pre-light emission ends. A period from the moment when one flash starts to emit light to the moment when the next flash starts to emit light is called an emission cycle. The light emission period and the light emission period are specified values and cannot be changed by the digital camera 110. The light emission period of the first flash 201 and the second flash 202 is shorter than the shortest imaging period.

  In the case of performing pre-flash using a plurality of flashes, the CPU block 162 transmits a flash signal to the first flash 201 and the second flash 202 in synchronization with the synchronization signal output from the TG 154. The image sensor performs imaging in accordance with this and outputs photometric data. The DSP 160 processes the photometric data and measures the brightness due to the pre-emission.

  Next, a timing chart according to a comparative example will be described with reference to FIG. In the comparative example, pre-light emission is performed using the first flash 201 and the second flash 202 without performing the processing according to the present embodiment, and the photometry CCD 138 performs photometry. As described above, the light emission period T1 and the light emission period T2 of the first flash 201 and the second flash 202 are specified values, and the digital camera 110 cannot change them. Shorter than the shortest imaging cycle of the photometric CCD 138. The photometric CCD 138 operates in the shortest imaging cycle.

  First, the pre-light emission timing will be described. First, the first flash 201 performs flat light emission only for a predetermined light emission period T1. Next, after the first flash 201 starts flat light emission and after a predetermined light emission period T2, the second flash 202 performs flat light emission only during the light emission period T1. Then, the pre-flash is finished.

  Next, the imaging timing of the photometric CCD 138 will be described. When the SUB signal changes from Hi to Lo, the electronic shutter is opened and the photometric CCD 138 is exposed to start accumulating charges. Next, when the sensor gate signal becomes Hi, the photometric CCD 138 outputs charges. Thereby, photometric data is output. An exposure period T4 is a period from when the SUB signal becomes Lo until the sensor gate signal becomes Hi. The exposure period T4 is started again after a predetermined imaging period T3 from the time when the SUB signal becomes Lo to the next Lo, and then the photometric CCD 138 is exposed to output photometric data. And imaging is complete | finished.

  Here, the light emission period T1 of the second flash 202 does not include the entire second exposure period T4 by the photometric CCD 138. Therefore, the photometric data output from the photometric CCD 138 in the second exposure period T4 does not reflect the amount of illumination light from the second flash 202. Therefore, even if the DSP 160 determines the brightness of the pre-flash based on this, the brightness of the pre-flash cannot be accurately determined. On the other hand, as described above, the light emission period T1 and the light emission period T2 of the first flash 201 and the second flash 202 are defined values, and therefore the light emission periods T1 and T1 of the first flash 201 and the second flash 202 The light emission period T2 cannot be changed to match the exposure period T4 and the imaging period T3. In addition, since the photometric CCD 138 operates in the shortest imaging cycle, the imaging cycle T3 cannot be shortened to match the exposure period T4 with the light emission period T1. Since the exposure period T4 is also a minimum necessary period, it cannot be changed. Therefore, in the present embodiment, the light emission control process shown in FIG. 4 is performed, and photometric data that sufficiently reflects the amount of illumination light from the first flash 201 and the second flash 202 is obtained.

  FIG. 4 shows a timing chart of the light emission control process.

  First, the pre-light emission timing will be described. The DSP 160 starts the first imaging within the predetermined number of times before the timing when the first imaging starts, and before the time when the final imaging ends within the predetermined number of times. After that, the first flash 201 and the second flash 202 are controlled so that the final light emission within a predetermined number of times of light emission ends. Specifically, as described above, since the imaging cycle T3 of the photometric CCD 138 cannot be changed, the light emission timings of the first flash 201 and the second flash 202 are changed. First, the DSP 160 determines a timing when the light emission of the second flash 202 ends after the unstable period T6 after the final imaging time of the two imaging times, that is, the timing when the second imaging is completed. Then, the timing at which the first imaging is started is determined based on the timing at which the light emission ends, and the first flash 201 starts to emit light before the unstable time T5 before the timing at which the imaging starts. Next, the light emission timing of the first flash 201 is determined. Then, light emission signals are transmitted to the first flash 201 and the second flash 202 in accordance with the light emission time of the first flash 201 and the light emission time of the second flash 202, respectively. The unstable period T5 and the unstable period T6 are periods in which light emission by the first flash 201 and the second flash 202 becomes unstable. In the first flash 201 and the second flash 202, the amount of light becomes unstable during the unstable period T5 immediately after the start of light emission and the unstable period T6 just before the end of light emission. By not including the exposure period T4, it is possible to prevent photometry under an unstable light amount. Thereby, the first flash 201 and the second flash 202 emit light as follows. First, the first flash 201 performs flat light emission only for a predetermined light emission period T1. Next, after the first flash 201 starts flat light emission and after a predetermined light emission period T2, the second flash 202 performs flat light emission only during the light emission period T1. Then, the pre-flash is finished.

  Next, the imaging timing of the photometric CCD 138 will be described. When the SUB signal changes from Hi to Lo, the electronic shutter is opened and the photometric CCD 138 is exposed to start accumulating charges. Next, when the sensor gate signal becomes Hi, the photometric CCD 138 outputs charges. Thereby, photometric data is output. An exposure period T4 is a period from when the SUB signal becomes Lo until the sensor gate signal becomes Hi.

  Next, the SUB signal is set to Hi. The SUB signal is set to Lo after the imaging cycle T3 from when the SUB signal becomes Lo for the first time. As a result, the electronic shutter is closed until the first flash 201 is completed, and the first light emission period T1 is covered in the second exposure period T4, so that the first light emission affects the second exposure. Can be prevented. When the SUB signal is set to Lo, the exposure period T4 is started again, the photometric CCD 138 is exposed, and photometric data is output. And imaging is complete | finished.

  Here, the light emission period T1 of the second flash 202 includes the entire second exposure period T4 of the photometric CCD 138. Therefore, the photometric data output from the photometric CCD 138 in the second exposure period T4 reflects the amount of illumination light from the second flash 202. Therefore, if the DSP 160 determines the brightness of the pre-flash based on this, the brightness of the pre-flash can be accurately determined.

  According to the present embodiment, accurate exposure or photometry can be performed even when the flash emits light a plurality of times.

  Further, by using an electronic shutter, light emission of a plurality of times can be measured under the same conditions.

  Note that the number of flashes is not limited to two and may be plural.

  Further, the first flash 201 and the second flash 202 may be connected to the digital camera 110 wirelessly instead of the cable 204.

  In addition to or instead of the first flash 201 and the second flash 202, the built-in flash 203 may be used.

  Note that in any of the embodiments. The digital camera 110 may be a so-called compact camera, single-lens reflex camera, or mirrorless single-lens camera.

  A solid-state image sensor such as a CMOS (complementary metal oxide semiconductor) image sensor may be used instead of the CCD.

DESCRIPTION OF SYMBOLS 100 Imaging system 110 Digital camera 120 Imaging lens 121 Zoom lens 122 Diaphragm blade 123 Focusing lens 130 Camera body 131 CCD for imaging
132 Shutter curtain 133 Return mirror 133a Storage position 134 AF sensor 135 Focusing motor 136 Aperture blade motor 137 Auxiliary LED
138 CCD for photometry
139 Eyepiece 140 Penta prism 140a Reflecting surface 141 Sub mirror 150 AFE
151 CDS
152 AGC
153 A / D converter 160 DSP
161 CCD I / F
162 CPU block 171 SDRAM
172 ROM
201 First flash 202 Second flash 203 Built-in flash 204 Cable

Claims (10)

An imaging device that is used together with a lighting device that emits light at a predetermined light emission cycle at a predetermined light emission number of two or more,
A light emission control unit for controlling the timing when the illumination device emits illumination light;
An imaging device that captures the reflected light generated by reflecting the illumination light on the subject for a predetermined number of imaging times equal to the predetermined number of times of light emission in a predetermined imaging cycle;
The light emission control unit is configured to start the first light emission of the predetermined number of times of light emission before the timing of starting the first image pickup of the predetermined number of times of image pickup, and to perform the final image pickup of the predetermined number of image pickup times of time. An imaging device that controls the illumination device so that the last light emission of the predetermined light emission times ends after the time when the light emission ends.   The imaging apparatus according to claim 1, wherein the imaging apparatus includes an electronic shutter, and the electronic shutter is closed until at least the current light emission ends after the imaging apparatus ends the current imaging. The illumination device emits light for a predetermined light emission period per light emission,
The imaging element performs exposure by performing exposure for a predetermined exposure period per one imaging,
The said light emission control part controls the first light emission time so that the said exposure period may be included in the said light emission period in all the frequency | counts of light emission, when the said imaging period is longer than the said light emission period. Imaging device.   The light emission control unit is configured such that a period between a time when the first imaging is started out of the predetermined number of times and a time when the first light emission is started among the predetermined times is equal to or more than a first unstable period. The imaging apparatus according to claim 1, wherein the imaging apparatus is controlled.   The light emission control unit is configured such that a period between a timing at which the last imaging is finished out of the predetermined imaging times and a timing at which the last light emission is finished out of the predetermined times is equal to or longer than a second unstable period. The imaging device according to claim 1, wherein the imaging device is controlled.   The imaging device according to claim 1, wherein the imaging cycle is longer than the light emission cycle.   The imaging device according to claim 1, wherein there are a plurality of the illumination devices, and each illumination device emits light once at a predetermined light emission period. A signal processing unit,
The imaging device images reflected light and outputs imaging data;
The imaging apparatus according to claim 1, wherein the signal processing unit determines exposure using imaging data.   An imaging system comprising the imaging device according to claim 1 and the illumination device. Light is emitted a predetermined number of times equal to the predetermined number of times in a predetermined light emission period in accordance with a process of imaging the reflected light generated by reflecting the illumination light on the subject for a predetermined number of times at a predetermined imaging period. A method of controlling a lighting device that performs
Detecting a final imaging end time at which the final imaging is completed among the predetermined imaging times;
Determining a final light emission end time at which the final light emission ends among the predetermined light emission times after the final imaging end time;
Detecting a first imaging start time at which the first imaging is started among the predetermined imaging times;
Before the first imaging start time, a step of determining a first light emission start time at which the first light emission starts out of the predetermined number of light emission times, and a light emission of the illumination device according to the final light emission end time and the first light emission start time. And a step of controlling the timing.

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