JP5901323B2 - Imaging apparatus and illumination method for imaging - Google Patents

Description

  The present invention relates to an imaging apparatus and an illumination method for imaging.

  In order to acquire a clear moving image of a subject, when the subject is dark, photographing may be performed while illuminating the subject with illumination light. For example, in Patent Document 1, in order to prevent deterioration of a captured image due to a sudden change in light emission when the light is turned on and off, the light is turned on while slowly increasing the light emission until reaching a predetermined light emission. A technique for turning off the light while slowly reducing the light emission amount is disclosed.

  Patent Document 2 discloses a technique related to appropriately adjusting the light emission amount of illumination light. Further, in Patent Document 3, in order to acquire subject luminance in a state where illumination light is not irradiated in the adjustment of exposure at the time of shooting, the light is temporarily turned off, and after the subject luminance is acquired, the light is turned on again. Techniques to do this are disclosed.

JP-A-2-239780 JP-A-6-22209 JP 2006-318000 A

  When the illumination light is used, the light derived from the illumination light cannot be separated from other light. Therefore, when trying to acquire the brightness of the subject in the absence of illumination light for setting the exposure conditions including the amount of illumination light, etc., as disclosed in Patent Document 3, the illumination is temporarily turned off. . However, if the illumination is temporarily turned off during moving image shooting, the image becomes dark during the time period of the series of moving images, and the quality of the moving images deteriorates.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus and an illumination method for imaging that can appropriately control the amount of illumination light emission without deteriorating the quality of moving images.

In order to achieve the above object, according to an aspect of the present invention, an imaging apparatus includes an image acquisition unit that continuously acquires an image of a subject, a luminance acquisition unit that acquires the luminance of the subject as subject luminance, and a light emission amount. The illumination unit is variable, and the subject luminance is acquired from the luminance acquisition unit, and the light emission amount is increased if the subject luminance satisfies a light increase condition, and the light emission is performed if the subject luminance satisfies a light decrease condition. A controller for repeatedly performing the increase / decrease lamp process for decreasing the amount , wherein the control unit obtains the resolution for changing the light emission amount from the illumination unit, and the unit for the increase / decrease lamp process according to the resolution. It is characterized by changing the number of times per hour .

In order to achieve the above object, according to one aspect of the present invention, an illumination method for imaging includes acquiring an image of a subject continuously, acquiring the luminance of the subject as subject luminance, the increase outgoing light amount satisfies the subject brightness is a multiple flash conditions, obtaining a said object brightness is carried out by causing decrease lamp processing reduces the amount of light emission satisfies a reduced lamp condition, the resolution of the light emission amount of change And the number of times of the increase / decrease lamp process per unit time is changed according to the resolution when the subject luminance is acquired and the increase / decrease lamp process is repeatedly performed. It is characterized by.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can control illumination light emission amount appropriately, and the illumination method for imaging can be provided, without deteriorating the quality of a moving image.

1 is a block diagram illustrating an example of a configuration of an imaging apparatus according to each embodiment of the present invention. The figure which shows the circuit structural example of the light unit which concerns on each embodiment. 6 is a flowchart illustrating an example of the operation of the imaging apparatus according to each embodiment. The flowchart which shows an example of the light emission amount control process which concerns on each embodiment. The flowchart which shows an example of the light control judgment process which concerns on 1st Embodiment. 6 is a flowchart illustrating an example of luminance determination processing according to the first embodiment. The flowchart which shows an example of the light increase process which concerns on each embodiment. The flowchart which shows an example of the light reduction process which concerns on each embodiment. The figure for demonstrating an example of the relationship between the light increase brightness, the light reduction brightness, and the light extinction brightness which concerns on 1st Embodiment. The figure for demonstrating an example of the setting of the light extinction brightness | luminance which concerns on 1st Embodiment. 6 is a timing chart showing an example of a light emission amount control process according to the first embodiment. The figure for demonstrating the under amount which concerns on 2nd Embodiment. The figure for demonstrating an example of the relationship of the light increase under amount, the light reduction under amount, and the light extinction under amount which concerns on 2nd Embodiment. The flowchart which shows an example of the light control judgment process which concerns on 2nd Embodiment. The flowchart which shows an example of the brightness | luminance determination process which concerns on 2nd Embodiment. The flowchart which shows an example of the backlight determination process which concerns on 2nd Embodiment. The figure which shows an example of the increase / decrease judgment table which concerns on 2nd Embodiment.

[First Embodiment]
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of the configuration of the photographing apparatus according to the present embodiment. The photographing apparatus 1 is a camera capable of capturing moving images, such as a digital single lens reflex camera, a digital mirrorless single lens camera, and a video camera. The imaging apparatus 1 includes a body unit 100, a lens unit 200 including a lens barrel that is replaceably attached to the body unit 100, and a light unit 180 that is detachable from the body unit 100. The lens unit 200 is detachable through a lens mount (not shown) provided on the front surface of the body unit 100. In the present embodiment, the lens unit 200 can be exchanged for the body unit 100. However, the present invention is not limited to this, and the body unit 100 and the lens unit 200 may be fixed. The body unit 100 is loaded with a recording medium 131 for recording captured image data. Here, the recording medium 131 is connected to the body unit 100 via the communication connector 130.

  The lens unit 200 includes photographing lenses 210a and 210b, a diaphragm 203, a lens driving mechanism 204, a diaphragm driving mechanism 202, and a lens control microcomputer 201 (hereinafter referred to as Lμcom 201). The Lμcom 201 is electrically connected to a body control microcomputer 101 (hereinafter referred to as Bμcom101), which will be described later, via a communication connector 160, and exchanges various data with the body control microcomputer 101. Lμcom 201 is controlled by Bμcom101. The Lμcom 201 drives and controls each part in the lens unit 200 such as the lens driving mechanism 204 and the aperture driving mechanism 202.

  The taking lenses 210 a and 210 b are driven in the optical axis direction by a DC motor (not shown) provided in the lens driving mechanism 204 under the control of Lμcom 201. The diaphragm 203 is driven by a stepping motor (not shown) provided in the diaphragm driving mechanism 202 under the control of Lμcom 201.

  The body unit 100 includes a body control microcomputer 101 (Bμcom 101) for controlling the operation of each unit, an image processing IC 102, a face detection IC 103, an SDRAM (Synchronous Dynamic Random Access Memory) 104, a luminance acquisition IC 105, a ROM 106, , An image sensor driving IC 110, an image sensor 111, a shutter unit 120, a shutter control drive circuit 121, a communication connector 130, a liquid crystal monitor 140, a camera operation switch 150, and a communication connector 160.

  The Bμcom 101 has functions such as a control unit that controls the entire operation of the camera, a counting unit, a mode setting unit, a detection unit, a determination unit, and a calculation unit. Bμcom 101 is connected to Lμcom 201 via a communication connector 160. The Bμcom 101 is connected to a shutter control drive circuit 121, an image processing IC 102, a face detection IC 103, an SDRAM 104, a luminance acquisition IC 105, a ROM 106, a camera operation switch 150, a light unit 180, and a power source (not shown). This power supply includes a battery (not shown), converts the battery voltage to a voltage required by each unit of the camera via a power supply circuit, and supplies power to each unit. The ROM 106 stores programs and other information used by the Bμcom 101 and the like. The Bμcom 101 executes processing based on a program read from the ROM 106.

  The shutter unit 120 is, for example, a focal plane type shutter unit provided on the optical axis of a light beam incident from the lens unit 200. The shutter control drive circuit 121 is connected to Bμcom 101 and drives the shutter unit 120 under the control of Bμcom101. The shutter control drive circuit 121 controls the movement of a front curtain and a rear curtain (not shown) in the shutter unit 120, and controls a signal for controlling the opening / closing operation of the shutter with the Bμcom 101 and a signal when the travel of the front curtain is completed. Give and receive.

  The image sensor 111 is provided behind the shutter unit 120 on the optical axis of the light beam incident from the lens unit 200. The light beams that have passed through the taking lenses 210 a and 210 b and the stop 203 in the lens unit 200 are imaged on the image sensor 111. The image sensor 111 photoelectrically converts the formed subject image to generate an analog electrical signal. The image sensor 111 is photoelectrically controlled by the image sensor driving IC 110. The analog electrical signal generated by the image sensor 111 is converted by the image sensor drive IC 110 into a digital electrical signal to be processed by the image processing IC 102 and output to the image processing IC 102. The image processing IC 102 performs image processing such as converting a digital electric signal input from the image sensor driving IC 110 into an image signal.

  The image processing IC 102 is connected to the face detection IC 103, SDRAM 104, luminance acquisition IC 105, communication connector 130, and liquid crystal monitor 140 in addition to the Bμcom 101. The image processing IC 102 temporarily stores data in the SDRAM 104 provided as a storage area or reads temporarily stored data in image processing. The image processing IC 102 records the created image signal on the recording medium 131 via the communication connector 130 under the control of the Bμcom 101. The recording medium 131 is an external recording medium such as various semiconductor memory cards and an external hard disk drive (HDD). The recording medium 131 is mounted so as to be communicable with the body unit 100 via the communication connector 130 and exchangeable. Further, the image processing IC 102 outputs the created image signal to the liquid crystal monitor 140 under the control of the Bμcom 101, and causes the liquid crystal monitor 140 to display an image. The liquid crystal monitor 140 is not limited to a liquid crystal display, and may be replaced with another display such as an organic EL display. The liquid crystal monitor 140 displays an image based on the image signal generated by the image processing IC 102 and notifies the user (photographer) of the operation state of the camera by display output. Further, the image processing IC 102 outputs the created image signal to the face detection IC 103 in order to cause the face detection IC 103 to perform face detection processing. As described above, the electronic recording display function is realized together with the electronic imaging function with the image processing IC 102 as the center.

  The luminance acquisition IC 105 acquires an image from the image processing IC 102 and calculates the luminance of the subject. This subject luminance is output to Bμcom 101. The Bμcom 101 determines the exposure condition based on the subject brightness, and drives the lens unit 200, the shutter control drive circuit 121, and the like to perform exposure adjustment. Further, the Bμcom 101 controls the operation of the light unit 180 based on the subject brightness.

  A camera operation switch 150 is connected to Bμcom 101. The camera operation switch 150 includes a release button for instructing execution of a shooting operation, a mode change switch for switching the shooting mode to a continuous shooting mode or a normal shooting mode, a power switch for switching the power on / off, and the like. It includes operation buttons (operation means) necessary for the operation. When an operation by the user is input, a signal is input from the camera operation switch 150 to the Bμcom 101.

  The light unit 180 includes a movie light 181, a current limiting circuit 182, a light control microcomputer 183 (hereinafter referred to as a light control μcom 183), and a light communication connector 185. The movie light 181 includes an LED, for example. The movie light 181 changes the light emission amount according to the input current. The current limiting circuit 182 adjusts the current input to the movie light 181. The current limiting circuit 182 is realized using a known technique such as a transistor or pulse width modulation (PWM). The write communication connector 185 connects the Bμcom 101 of the body unit 100 and the write control μcom 183. The light control μcom 183 controls the operation of the movie light 181 under the control of Bμcom101. The circuit of the light unit 180 can be expressed as shown in FIG. The light unit 180 may be detachable from the body unit 100, or may be fixed to the body unit 100. A light source other than the LED may be used for the movie light 181.

  The operation of the imaging apparatus 1 will be described with reference to the drawings. First, the photographing operation will be described. When receiving a signal for controlling the driving of the shutter from the Bμcom 101, the shutter control driving circuit 121 controls the shutter unit 120 to cause the shutter to perform an opening / closing operation. At that time, when the light control microcomputer 183 receives a signal for controlling the movie light 181 from the Bμcom 101 via the light communication connector 185, the light control microcomputer 183 controls the current limiting circuit 182 to turn on the movie light 181. .

  The light beams from the photographing lenses 210 a and 210 b are guided to the image sensor 111. Under the control of Bμcom 101, a digital electric signal that is photoelectrically converted by the image sensor 111 and converted by the image sensor drive IC 110 is input to the image processing IC 102. The image processing IC 102 stores the digital electric signal input from the image sensor driving IC 110 in the SDRAM 104 which is a temporary storage memory. The SDRAM 104 is also used as a work area for the image processing IC 102 to perform image processing.

  The image processing IC 102 converts a digital electric signal into an image signal. If the image signal is a still image, the image processing IC 102 performs image processing for converting the image signal into, for example, JPEG data. If the image signal is a moving image, the image processing IC 102 converts the image signal into a movie file. In moving image shooting, for example, exposure is continuously performed at a rate of about 60 frames per second. The image processing IC 102 records JPEG data and movie files on the recording medium 131.

  Next, the live view operation will be described. The light beams from the photographing lenses 210 a and 210 b are guided to the image sensor 111. For example, the image sensor 111 continuously performs exposure at a rate of about 60 images per second, and the image sensor drive IC 110 generates image data. The image processing IC 102 converts this image data into a video signal. The image processing IC 102 provides a video signal to the liquid crystal monitor 140 to display a moving image of the subject on the liquid crystal monitor 140. Such display is called “live view” and is performed using a known technique. In order to display the live view display of the image data on the liquid crystal monitor 140 with this camera, the user may select the live view mode by operating the mode change switch in the camera operation switch 150 described above. Hereinafter, the live view may be abbreviated as “LV”.

  During the LV operation, the light flux from the photographing lenses 210 a and 210 b is always guided to the image sensor 111. The image processing IC 102 performs a well-known distance measurement process on the subject based on the image data. Hereinafter, the process of ranging and automatic focusing on the subject performed by the image processing IC 102 and the Bμcom 101 based on the image data will be referred to as “LVAF”. Further, the image processing IC 102 outputs the image data to the luminance acquisition IC 105. The luminance acquisition IC 105 performs photometric processing for acquiring the brightness of the subject. Hereinafter, the photometry processing of the brightness of the subject performed by the luminance acquisition IC 105 is referred to as “LV photometry”.

  Next, moving image recording will be described with reference to the flowchart shown in FIG. When the power of the body unit 100 is ON, the Bμcom 101 determines whether or not the lens unit 200 attached and the attached light unit 180 are recognized in step S101. When the lens unit 200 and the light unit 180 are not recognized, the Bμcom 101 repeats the process of step S101 until the recognition is performed.

  When the lens unit 200 and the light unit 180 are recognized, the Bμcom 101 acquires information on the lens unit 200 via the communication connector 160 in step S102, and the Lμcom 201 drives the lens position and the aperture of the lens unit 200. Tell instructions. Further, the Bμcom 101 acquires information of the light unit 180 via the light communication connector 185 and transmits an instruction of the light emission amount to the light control microcomputer 183.

  Bμcom 101 starts the live view operation in step S103. In other words, the Bμcom 101 controls the aperture, shutter speed, sensitivity, light emission amount, and the like according to, for example, a change in luminance. Control of the light emission amount of the movie light 181 according to this embodiment will be described later with reference to FIGS.

  Bμcom 101 determines whether or not the release button has been pressed in step S104. Until the release button is pressed, Bμcom 101 repeats the determination in step S104 and continues the live view operation. When the release button is pressed, the Bμcom 101 causes the image processing IC 102 to process the image obtained in the live view and starts recording data on the recording medium 131 in step S105.

  The Bμcom 101 performs exposure control in step S106. In this exposure control, as in step S103, the aperture, shutter speed, sensitivity, and light emission amount are controlled according to the luminance of the subject. The light emission amount control of the movie light 181 according to the present embodiment will be described later with reference to FIGS.

  Bμcom 101 determines whether or not the release button has been pressed in step S107. Until the release button is pressed, the Bμcom 101 repeats the exposure control in step S106 to continue moving image shooting. When the release button is pressed, the Bμcom 101 executes a recording completion process in step S108, records the obtained moving image on the recording medium 131 as a moving image file, and ends the moving image recording. Bμcom 101 causes the liquid crystal monitor 140 to display that moving image recording has been stopped. Thereafter, the processing returns to step S101. As a result, the live view operation is started again in step S103. The operation shown here is a general moving image recording operation of a camera, except for the light emission amount control process performed in step S103 or step S106.

  The light emission amount control according to the present embodiment in the exposure control process will be described with reference to FIGS. First, the main flow of light emission control will be described with reference to FIG. The process shown in FIG. 4 is performed every 1/60 seconds, which is the frame rate, for example.

  In step S201, the Bμcom 101 acquires the luminance of the subject. In step S202, the Bμcom 101 determines whether it is the light emission amount change timing. Here, the cycle of the light emission amount change timing is determined according to the characteristics of the light unit 180. In the present embodiment, the light unit 180 has a dimming resolution of 1/3 step, that is, the light emission amount can be changed in steps of 1/3 step. Based on this, the cycle of the light emission amount change timing is, for example, 333 ms ( 1/3 seconds). When the light unit 180 is detachable from the body unit 100 and various light units 180 having various performances are used, the light control resolution is transmitted to the Bμcom 101 for each light unit 180. Bμcom 101 sets the period of the light emission amount change timing so that the speed of the light emission amount change becomes a predetermined value according to the light control resolution of the light unit 180.

For example, when the light unit 180 can execute a predetermined light amount change, that is, has a predetermined dimming resolution and changes the light emission amount so that the change speed is α steps per second, the light amount change timing Is obtained by the following equation.
"Dimming resolution (number of steps)" x "α (step)" = "Cycle of light change timing (seconds)"
That is, when the α stage is 1, when the dimming resolution is 1/3 stage, the light quantity change timing cycle is 0.333 seconds, and when the dimming resolution is 1/4 stage, the light quantity change timing period is When the dimming resolution is 1/8 stage for 0.25 seconds, the light quantity change timing cycle is 0.125 seconds.

  If it is determined in step S202 that it is not the light emission amount change timing, the process returns to the exposure control process. On the other hand, when it is determined that it is the light emission amount change timing, the process proceeds to step S203. That is, in this embodiment, the light emission control process proceeds to step S203 at a rate of once every 20 frames. In step S203, the Bμcom 101 determines whether or not the variable “increase / decrease lamp process” is negative. Here, as will be described later, the variable “increase / decrease lamp process” is set to “1” when increasing the light emission amount of the movie light 181 and set to “−1” when decreasing the light emission amount. It is. When it is determined that the value is not negative, the Bμcom 101 determines whether or not the variable “increase / decrease lamp process” is positive in step S204. When it is determined that the value is not positive, the Bμcom 101 executes a dimming determination process described later in step S205. Thereafter, the process returns to the exposure control process. When it is determined in step S204 that the variable “increase / decrease lamp process” is positive, the Bμcom 101 executes a later-described lamp increase process in step S206. Thereafter, the process returns to the exposure control process. When it is determined in step S203 that the variable “increase / decrease lamp process” is negative, the Bμcom 101 executes a lamp reduction process described later in step S207. Thereafter, the process returns to the exposure control process.

  The dimming determination process executed in step S205 will be described with reference to the flowchart shown in FIG. In step S301, the Bμcom 101 executes a luminance determination process. Thereafter, the process returns to the light emission amount control process. The brightness determination process executed in step S301 will be described with reference to the flowchart shown in FIG. The Bμcom 101 determines whether or not the subject brightness acquired by the brightness acquisition IC 105 in step S401 is equal to or lower than the increased lamp brightness. When it is determined that the brightness is less than the increased lamp brightness, the Bμcom 101 increments the variable “lighting counter” by 1 in step S402. However, the “lighting counter” is set to 6 at maximum, and is not increased from 6. Thereafter, the process proceeds to step S406.

  When it is determined in step S401 that the subject brightness is not less than the increased lamp brightness, the Bμcom 101 determines in step S403 whether the subject brightness is equal to or higher than the decreased lamp brightness. When it is determined that the brightness is not less than the light reduction brightness, the Bμcom 101 decreases the variable “lighting counter” by 1 in step S404. However, the “lighting counter” is set to −6 at the minimum, and is not decreased from −6. Thereafter, the process proceeds to step S406. If it is determined in step S403 that the subject brightness is not equal to or less than the reduced lamp brightness, the Bμcom 101 sets the variable “lighting counter” to 0 in step S405. Thereafter, the process proceeds to step S406.

  In step S406, the Bμcom 101 determines whether the lighting counter is 6 or more. When it is determined that the lighting counter is 6 or more, the Bμcom 101 sets the variable “increase / decrease lamp process” to 1 in step S407. Thereafter, the process returns to the dimming determination process. When it is determined in step S406 that the lighting counter is not 6 or more, the Bμcom 101 determines whether or not the lighting counter is −6 or less in step S408. When it is determined that the lighting counter is equal to or less than −6, the Bμcom 101 sets the variable “increase / decrease lamp process” to −1 in step S409. Thereafter, the process returns to the dimming determination process. When it is determined in step S408 that the lighting counter is not equal to or less than −6, the process returns to the dimming determination process.

  Here, as described with reference to FIG. 6, when the lighting counter becomes 6 or more, that is, when the subject brightness becomes less than the increased brightness for 6 consecutive cycles, the light emission amount of the movie light 181 increases. Be made. On the other hand, when the lighting counter becomes -6 or less, that is, when the subject brightness becomes equal to or higher than the reduced brightness for 6 consecutive cycles, the light emission amount of the movie light 181 is reduced. As described above, by using the lighting counter, it is possible to prevent the light emission amount of the movie light 181 from being finely changed due to an instantaneous change in subject luminance. Of course, the lighting counter 6 or -6 used for determining whether or not the movie light 181 is increased or decreased is merely an example, and other numbers may be used. Also, the absolute values of the values used for the determination of increasing light and the determination of decreasing light may be different values. By adjusting these values, the sensitivity of operation for increasing or decreasing lighting can be adjusted.

  The light increase process executed in step S206 will be described with reference to the flowchart shown in FIG. In step S501, the Bμcom 101 determines whether the subject brightness is equal to or higher than the increased lamp brightness. When it is determined that the brightness is higher than the increased lamp brightness, the Bμcom 101 sets the variable “increase / decrease lamp process” to 0 in step S502. Thereafter, the process returns to the light emission amount control process.

  When it is determined in step S501 that the subject brightness is not equal to or higher than the increased lamp brightness, the Bμcom 101 determines in step S501 whether or not the light emission amount of the movie light 181 is the maximum light emission amount. When it is determined that the light emission amount is not the maximum light emission amount, Bμcom 101 outputs an instruction to the light control microcomputer 183 so as to increase the light emission amount of the movie light 181 by one step in step S504. Thereafter, the process returns to the light emission amount control process. When it is determined in step S503 that the light emission amount is the maximum, the Bμcom 101 sets the variable “increase / decrease lamp process” to 0 in step S505. Thereafter, the process returns to the light emission amount control process.

  The light reduction process executed in step S207 will be described with reference to the flowchart shown in FIG. In step S601, the Bμcom 101 determines whether the subject brightness is equal to or less than the reduced lamp brightness. When it is determined that the brightness is less than the reduced lamp brightness, the Bμcom 101 sets the variable “increase / decrease lamp process” to 0 in step S602. Thereafter, the process returns to the light emission amount control process.

  When it is determined in step S601 that the subject brightness is not less than the reduced lamp brightness, the Bμcom 101 determines whether or not the light emission amount of the movie light 181 is the minimum light emission amount in step S603. When it is determined that the light emission amount is not the minimum light emission amount, Bμcom 101 outputs an instruction to the light control microcomputer 183 so that the light emission amount of the movie light 181 is decreased by one step in step S604. Thereafter, the process returns to the light emission amount control process. When it is determined in step S603 that the light emission amount is the minimum, the Bμcom 101 determines in step S605 whether the subject luminance is equal to or higher than the extinction luminance. When it is determined that the luminance is not higher than the extinction luminance, the processing returns to the light emission amount control processing. When it is determined that the brightness is not less than the turn-off brightness, the Bμcom 101 turns off the movie light 181 in step S606. In step S607, the Bμcom 101 sets the variable “increase / decrease lamp process” to 0. Thereafter, the process returns to the light emission amount control process.

  Here, as shown in FIGS. 7 and 8, the movie light 181 is turned on or the amount of light emission is increased if the subject luminance is lower than the increased luminance (lighting luminance), and if the luminance is higher than the decreased luminance, the movie light is increased. If the light emission amount of 181 is reduced and is higher than the turn-off luminance, the movie light 181 is turned off. Here, FIG. 9 shows the relationship between the increased brightness (lighting brightness), the decreased brightness, and the turn-off brightness. As shown in this figure, a predetermined brightness difference is provided between the increased lamp brightness and the decreased lamp brightness, and the threshold for determining whether to increase the lamp is different from the threshold for determining whether to decrease the lamp. That is, hysteresis is provided in the light control. Similarly, a predetermined luminance difference is provided between the lighting luminance and the extinguishing luminance, and the threshold value for determining lighting and the threshold value for determining lighting are different. That is, hysteresis is provided in the light control. Similarly, a predetermined luminance difference is provided between the reduced-light luminance and the turned-off luminance, and the threshold for determining reduced light and the threshold for determining turned-off are different. That is, hysteresis is provided in the light control. These hysteresis prevents frequent increases and decreases in the light emission amount of the movie light 181 and frequent repetition of lighting and extinguishing. Note that the difference between the increased brightness and decreased brightness is greater than the dimming resolution of the movie light 181.

  The reason why the turn-off brightness is provided separately from the reduced lamp brightness is as follows. Between the maximum light emission amount and the minimum light emission amount, the light amount is changed by one step as described above. On the other hand, the light amount difference between the minimum light emission amount and the extinction is larger than one step. Therefore, for example, when the subject is nearby, the subject brightness differs greatly between when the movie light 181 is turned on with the minimum light emission amount and when the movie light 181 is turned off, and there is a possibility that the turning on and off are repeated. Therefore, in this embodiment, the turn-off brightness is set so that the turn-on and turn-off are not repeated even under the worst conditions where the subject is nearby.

  The extinction brightness is set as follows, for example. That is, it is determined based on the minimum light emission amount of the movie light 181. The case where the maximum light emission amount of the movie light 181 is 100 Lux at a distance of 1 m will be described as an example. The maximum light emission amount of the movie light 181 is stored in the movie light 181. Assume that the subject has the worst case with a reflectance of 100%. When the subject is present at a distance of 1 m when the movie light 181 is used at the maximum light emission amount, BV (Brightness Value) obtained by the imaging device 1 is calculated as 3. Here, the worst condition in which the subject is closest is assumed. That is, for example, a case where the distance to the subject is 12.5 cm is assumed. When the distance is halved, the converted BV value is +2 steps, so when the distance is from 1 m to 12.5 cm, it is +6 steps. Therefore, when the distance is 12.5 cm, the converted BV value is 9.

  It is assumed that the minimum light emission amount of the movie light 181 is 1/16 of the maximum light emission amount. Such a light amount ratio of the movie light 181 is also stored in the movie light 181. The minimum light emission amount is -4 steps of the maximum light emission amount. Therefore, the converted BV value of the subject with 100% reflectance located at 12.5 cm at the minimum light emission amount is 5. In the present embodiment, for example, this BV value 5 is used as the extinction brightness. Thus, by using the converted BV value under the worst condition as the extinguishing luminance, it is possible to prevent the lighting and extinguishing from being repeated.

  In the above example, the worst condition is that the distance to the subject is 12.5 cm. However, this distance may be, for example, the shortest focusing distance of the lens, or the shortest focusing distance of the lens that can be attached to the imaging apparatus 1. The shortest in-focus distance among the in-focus distances may be used, or the in-focus distance calculated in the autofocus (AF) operation may be used.

  In setting the extinction brightness, the angle of view by the lens unit 200 and the irradiation angle of the light unit 180 may be considered. This will be described in detail with reference to FIG. The range on the camera body side of the intersection 313 where the angle of view 311 by the lens unit 200 and the irradiation angle 312 of the light unit 180 intersect is defined as an unilluminable range. If the illumination impossible range is longer than the shortest focusing distance, the turn-off luminance may be lowered by replacing the shortest focusing distance with the illumination impossible range.

  The increased lamp brightness is, for example, BV when the aperture value (AV) is opened, the shutter speed (TV) is the longest time that can be set for moving image shooting, and the sensitivity (SV) of the image sensor 111 is the highest sensitivity. = BV value calculated by AV + TV-SV. Similarly, for the reduced lamp brightness, for example, when the aperture value (AV) is opened and the shutter speed (TV) can be set for moving image shooting, for example, when the frame rate per second is 60 fps, The maximum time is 1/60 seconds, and the TV value is “6”), and the BV value calculated when the sensitivity (SV) of the image sensor 111 is the lowest sensitivity can be obtained. Also, these values may be adjusted by the following amount. That is, a predetermined value may be used without opening the aperture so that the depth of field does not become shallow, and when calculating the reduced lamp brightness, the shutter is moved to a speed at which the moving image derived from the high-speed shutter speed does not matter. You may increase the speed. For example, when the frame rate is 60 fps, the feeling of disparity does not matter if it is about half to ¼ (the TV value may be replaced with 7 to 8) of the “maximum time for moving image setting”. The BV value obtained by such adjustment can be used as the increased or decreased brightness.

  FIG. 11 shows a timing chart of the operation according to the present embodiment. In this figure, the upper part shows the subject brightness, and the lower part shows the light emission amount of the movie light 181, that is, the amount of current input to the movie light 181. In the example shown in this figure, the movie light 181 is initially turned off. When six cycles of 333 ms, that is, 2 seconds have elapsed after the subject luminance falls below the increased luminance, the movie light 181 first emits light with the minimum light emission amount. Thereafter, while the subject luminance is lower than the increased luminance, the light emission amount increases by one step of the dimming resolution (1/3 step), and when the luminance exceeds the increased luminance, the increase in the light emission amount stops.

  Furthermore, when the subject brightness rises and exceeds the dimming brightness for 6 cycles of 333 ms, ie 2 seconds, while the subject brightness exceeds the dimming brightness, one step of dimming resolution (1/3 step) The amount of light emission decreases by minutes. Here, even if the subject brightness is higher than the reduced brightness, if the brightness is less than the turn-off brightness, the light emission amount of the movie light 181 can be reduced only to the minimum brightness. When the subject brightness exceeds the turn-off brightness, the movie light 181 is turned off.

  Thus, for example, the image sensor 111 functions as an image acquisition unit that continuously acquires images of a subject. For example, the luminance acquisition IC 105 functions as a luminance acquisition unit that acquires the luminance of the subject as the subject luminance. For example, the light unit 180 functions as an illumination unit whose light emission amount is variable. For example, the Bμcom 101 functions as a control unit that acquires subject luminance and repeatedly performs an increase / decrease lamp process that increases the light emission amount when the subject luminance satisfies the lighting increase condition and decreases the light emission amount when the subject luminance satisfies the light reduction condition. To do.

  According to the present embodiment, since the light emission amount of the movie light 181 is adjusted according to the subject brightness at that time including the light of the movie light 181, moving image shooting can be performed under an appropriate light amount. According to this embodiment, even if the subject brightness when the movie light 181 is turned off is unknown, the light emission amount of the movie light 181 can be adjusted appropriately. At this time, since the movie light 181 is not turned off for determining the exposure condition, the quality of the moving image is not deteriorated.

  In the present embodiment, the adjustment of the light emission amount in the light light emission amount control process is performed every 333 ms. This period is determined according to the dimming resolution of the light unit 180 as described above. Here, since the cycle of the light emission amount changing operation is determined according to the light control resolution of the light unit 180, the light emission amount change amount per unit time, that is, the light emission amount change speed is constant regardless of the characteristics of the light unit 180. It becomes. By setting this speed to a value that looks best in a moving image that is acquired, it is possible to acquire a moving image that looks good with no sense of incongruity with respect to changes in the amount of light emission.

  In the present embodiment, the luminance acquisition IC 105 calculates the subject luminance based on the captured image. However, the present invention is not limited to this. For example, an exposure meter may be separately provided in the body unit 100, and the subject brightness may be calculated based on the output of the exposure meter. In the case of an imaging apparatus in which exposure conditions such as an aperture value and a shutter speed are determined based on the acquired image as in the present embodiment, the light emission amount adjustment of the light unit 180 is also calculated based on the image. By using the subject brightness, the configuration of the apparatus can be simplified.

[Second Embodiment]
A second embodiment of the present invention will be described. Here, differences from the first embodiment will be described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted. In the present embodiment, it is determined whether or not backlight is generated using the brightness of the face portion detected by the face detection IC 103, and the determination of the backlight and the subject brightness obtained in the same manner as in the first embodiment are used. Based on this, the increase / decrease of the movie light 181 is controlled.

  In the present embodiment, for example, the face detection IC 103 detects the face 301 in an image as shown in FIG. The Bμcom 101 determines the variable “backlight increase / decrease determination” based on the under amount obtained from “under amount” = “face luminance” − “total luminance”, for example, using the face luminance and the overall luminance.

  For example, as shown in FIG. 13, a light increase under amount, a light decrease under amount, and a turn-off under amount are set for the main subject, that is, the face under amount. If the under amount is less than or equal to the increased lamp under amount, the variable “backlight increase / decrease determination” is set to “1”, and if the under amount is greater than or equal to the reduced lamp under amount, “−1” is set to the variable “backlight increase / decrease determination”. Is set. In the present embodiment, the turn-off brightness is set based on the face brightness.

  The light emission amount control process according to the present embodiment is the same as the light emission amount control process according to the first embodiment described with reference to FIG. The dimming determination process according to the present embodiment will be described with reference to FIG. In step S701, the Bμcom 101 executes a luminance determination process.

  The brightness determination process will be described with reference to FIG. This brightness determination process is the same as the brightness determination process described with reference to FIG. 6, and the variable “brightness increase / decrease determination” is set instead of the variable “increase / decrease lamp process”. As shown in FIG. 15, steps S801 to S809 correspond to steps S401 to S409 of the luminance determination process described with reference to FIG.

  That is, Bμcom 101 determines whether or not the subject brightness is equal to or lower than the increased brightness in step S801. When it is determined that the subject brightness is equal to or lower than the increased brightness, the variable “lighting counter” is incremented by 1 in step S802. Thereafter, the process proceeds to step S806. When it is determined in step S801 that the subject brightness is not less than the increased lamp brightness, Bμcom 101 determines in step S803 whether or not the subject brightness is greater than the decreased lamp brightness, and is determined to be greater than or equal to the decreased lamp brightness. In step S804, the variable “lighting counter” is decremented by one. Thereafter, the process proceeds to step S806. When it is determined in step S803 that the subject brightness is not equal to or less than the reduced lamp brightness, the Bμcom 101 sets the variable “lighting counter” to 0 in step S805. Thereafter, the process proceeds to step S806.

  In step S806, the Bμcom 101 determines whether or not the lighting counter is 6 or more. When it is determined that the lighting counter is 6 or more, the Bμcom 101 sets the variable “luminance increase / decrease determination” to 1 in step S807. Thereafter, the process returns to the dimming determination process. When it is determined in step S806 that the lighting counter is not 6 or more, Bμcom 101 determines in step S808 whether or not the lighting counter is −6 or less, and it is determined that the lighting counter is −6 or less. In step S809, the variable “luminance increase / decrease determination” is set to −1. Thereafter, the process returns to the dimming determination process. When it is determined in step S808 that the lighting counter is not -6 or less, the process returns to the light adjustment determination process.

  Returning to the dimming determination process shown in FIG. Subsequent to the luminance determination process, the Bμcom 101 performs a backlight determination process in step S702. The backlight determination process will be described with reference to the flowchart shown in FIG. In step S901, the Bμcom 101 determines whether or not the under amount is equal to or less than the increased light under amount. When it is determined that the amount of light is less than or equal to the light increase under amount, the Bμcom 101 increments the variable “backlight counter” by 1 in step S902. However, the “backlight counter” is set to 6 at the maximum and is not increased beyond 6. Thereafter, the process proceeds to step S906.

  When it is determined in step S901 that the under amount is not equal to or less than the increased lamp under amount, the Bμcom 101 determines whether or not the under amount is equal to or greater than the reduced lamp under amount in step S903. When it is determined that the light reduction under amount is greater than or equal to B, the Bμcom 101 decrements the variable “backlight counter” by 1 in step S904. However, the “backlight counter” is set to −6 at the minimum, and is not decreased from −6. Thereafter, the process proceeds to step S906. When it is determined in step S903 that the under amount is not equal to or less than the light reduction under amount, the Bμcom 101 sets the variable “lighting counter” to 0 in step S905. Thereafter, the process proceeds to step S906.

  In step S906, the Bμcom 101 determines whether or not the backlight counter is 6 or more. When it is determined that the backlight counter is 6 or more, the Bμcom 101 sets the variable “backlight increase / decrease determination” to 1 in step S907. Thereafter, the process returns to the dimming determination process. When it is determined in step S906 that the backlight counter is not 6 or more, the Bμcom 101 determines in step S908 whether the backlight counter is −6 or less. When it is determined that the backlight counter is −6 or less, the Bμcom 101 sets the variable “backlight increase / decrease determination” to −1 in step S909. Thereafter, the process returns to the dimming determination process. When it is determined in step S908 that the backlight counter is not −6 or less, the process returns to the light adjustment determination process.

  As described above, when the backlight counter becomes 6 or more, that is, when the under amount becomes less than the increase lamp under amount for 6 consecutive cycles, the variable “backlight increase / decrease determination” is set to 1, and the under light continues for 6 cycles. When the amount is equal to or greater than the light reduction under amount, −1 is set in the variable “backlight increase / decrease determination”.

  Returning to the dimming determination process shown in FIG. Following the backlight determination process, the Bμcom 101 executes an increase / decrease determination process in step S703. In the increase / decrease determination process, the Bμcom 101 is determined in the backlight determination process with the value of the variable “brightness increase / decrease determination” determined in the brightness determination process with reference to the increase / decrease determination table as shown in FIG. The value of the variable “increase / decrease lamp process” is determined based on the value of the variable “backlight increase / decrease determination”. In the present embodiment, as shown in FIG. 17, if 1 representing a light increase is set in any one of the value of the variable “brightness increase / decrease determination” and the value of the variable “backlight increase / decrease determination”, the variable “ The value of “increase / decrease lamp process” is set to 1 representing the increase lamp. In other cases, if −1 representing light reduction is set in one of the value of the variable “luminance increase / decrease determination” and the value of the variable “backlight increase / decrease determination”, the variable “increase / decrease light processing” Set the value to -1 for light reduction. If the value of the variable “brightness increase / decrease determination” and the value of the variable “backlight increase / decrease determination” are both set to 0 which does not increase or decrease the light, the value of the variable “increase / decrease lamp process” is set to 0 indicating the light emission amount maintenance. Set to.

  When the increase / decrease determination process ends, the process returns to the light emission amount control process described with reference to FIG. Based on the value of the variable “increase / decrease lamp process”, the lamp increase process described with reference to FIG. 7 and the lamp decrease process described with reference to FIG. 8 are performed, and the light emission amount of the movie light 181 is adjusted. .

  According to the present embodiment, in addition to the effects of the first embodiment, the face of the subject can be detected, and the light emission amount of the movie light 181 can be adjusted so that the brightness of this face is appropriate.

  In the present embodiment, the backlight determination process is performed based on the face of the subject. However, the present invention is not limited to this. A portion other than the face is set as the subject of interest, and the backlight determination process can be performed on the subject of interest.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the column of problems to be solved by the invention can be solved and the effect of the invention can be obtained. The configuration in which this component is deleted can also be extracted as an invention. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 100 ... Body unit, 101 ... Microcomputer for body control, 102 ... Image processing IC, 103 ... Face detection IC, 104 ... SDRAM, 105 ... Luminance acquisition IC, 110 ... Image sensor drive IC, 111 ... Image sensor, 120 ... Shutter Unit: 121 ... Shutter control drive circuit, 130 ... Communication connector, 131 ... Recording medium, 140 ... Liquid crystal monitor, 150 ... Camera operation switch, 160 ... Communication connector, 180 ... Light unit, 181 ... Movie light, 182 ... Current limiting circuit 183 ... Light control microcomputer, 185 ... Light communication connector, 200 ... Lens unit, 201 ... Lens control microcomputer, 202 ... Aperture drive mechanism, 203 ... Aperture, 204 ... Lens drive mechanism, 210a, 210b ... Photographing lens.

Claims (8)

An image acquisition unit for continuously acquiring images of the subject;
A luminance acquisition unit that acquires the luminance of the subject as the subject luminance;
An illumination unit having a variable light emission amount;
An increase / decrease lamp process that acquires the subject brightness from the brightness acquisition unit and increases the light emission amount when the subject brightness satisfies a light increase condition and decreases the light emission amount when the subject brightness satisfies a light decrease condition. A controller that repeatedly executes; and
Equipped with,
The controller is
Obtaining the resolution of the emission amount change from the illumination unit,
The imaging apparatus, wherein the number of times of the increase / decrease lamp processing per unit time is changed according to the resolution .   The imaging apparatus according to claim 1, wherein the increase / decrease lamp process further includes turning off the illumination unit when the subject brightness is in a turn-off condition. The controller is
Obtaining information representing the minimum light emission amount that is the minimum value of the light emission amount from the illumination unit,
Determining the extinguishing condition based on the minimum light emission amount;
The imaging apparatus according to claim 2. The controller is
If the subject brightness continuously satisfies the light increase condition for the first predetermined number of times, the light emission amount is increased,
Reducing the light emission amount if the subject brightness satisfies the light reduction condition continuously for a second predetermined number of times;
The imaging apparatus according to any one of claims 1 to 3 , wherein the imaging apparatus is configured as described above. Count per unit time of the increase and decrease lamp processing, imaging according to any one of claims 1 to 4 wherein the image acquiring unit per unit time is equal to or less than the number of times of acquiring the image apparatus. The light increase condition is that the subject brightness is lower than a light increase threshold,
The light reduction condition is that the subject brightness is higher than a light reduction threshold,
The turn-off condition is that the subject brightness is higher than a turn-off threshold ,
The light reduction threshold is higher than the light increase threshold, and the turn-off threshold is higher than the light reduction threshold.
The imaging apparatus according to claim 2 or 3, wherein The luminance obtaining unit, an imaging apparatus according to any one of claims 1 to 6, characterized in that to obtain the subject luminance on the basis of the image. Acquiring images of the subject continuously,
Obtaining the brightness of the subject as subject brightness;
And said object brightness increases the outgoing light amount satisfies the multiple flash conditions, implementing the light emission amount decreasing lamp processing to reduce satisfies the subject brightness is reduced lamp condition,
Obtaining a resolution of change of the light emission amount;
Comprising
The number of times of the increase / decrease lamp process per unit time is changed according to the resolution when the subject luminance is acquired and the increase / decrease lamp process is repeatedly performed. Lighting method.

Images