JP2017125981A - Exposure controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable exposure control without reference to an LED illumination state during focus detection.SOLUTION: An exposure controller comprises: an LED control section (4) which controls turning-on/off of an LED (2) by operating an external SW(1) and so on; an automatic focus control section (9) which performs automatic focus control; an automatic exposure control section (12) which performs automatic exposure control; and a photometry mode in which photometry is performed with a subject put in focus by LED illumination state detecting means (4, 21) of detecting the LED being turned on/off during the automatic focus control and the automatic focus control section, a photometric value is held until photography, and exposure control over the photography is performed with the photometric value. When the photography is performed in the photometric mode, re-photometry is performed if a turn-on state of the LED in photometry timing right before imaging and a turn-on state of the LED in focusing are different from each other, an image is picked up under exposure conditions based upon the re-photometry. Further, when the turn-on state of the LED in photometry timing right before the imaging and the turn-on state of the LED in the focusing are the same, photography is performed under exposure conditions of the photometric value in the focusing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to exposure control that reduces exposure unevenness in a configuration in which LED illumination is mounted on the lens side in order to eliminate the influence of a shadow on a lens shadow generated during macro shooting in a digital single-lens reflex camera.

  In recent digital still cameras and mobile phones with camera functions, with the increase in the brightness of LED elements, products using LEDs as flash devices at the time of camera flash photography have increased.

  In addition, as a feature of recent LED elements, since it is possible to continuously emit a relatively high intensity light amount, not only a flash for still image shooting, but also auxiliary light at the time of video shooting, It is also used as a focusing lamp for strobes.

  For example, when LED illumination is used as auxiliary light for focus, exposure control needs to be performed while paying attention to the relationship between lighting timing and photometry timing. For example, in the exposure control mode in which the focus operation is performed and the photometric value at the time of focusing is locked to perform shooting, focusing is performed with the LED illumination turned on. Since the photometric value is locked in a state where is lit, if the image is taken with the LED illumination turned off at the time of shooting, the image is taken with underexposure.

  As a method for avoiding this problem, Patent Document 1 can be cited. Patent Document 1 is characterized in that in the shooting mode in which the exposure is fixed, control is performed so that the lighting state of the LED is not changed at the timing of metering based on the subject brightness and the timing of shooting. Exposure control is performed so as not to be affected by the lights off.

JP 2012-73505 A

  However, in Patent Document 1, for example, when a user turns on LED illumination as auxiliary light for autofocus only during autofocusing and turns off the LED illumination during shooting (auxiliary light during focusing) However, the lighting state of the LED cannot be changed, so that the user's intended photograph cannot be taken. Also, when the user wants to take a picture with the LED light turned off during focus and the LED light turned on only during shooting (when the subject escapes when the LED light is turned on as auxiliary light for focusing) ) Cannot change the lighting state of the LED, and even in this case, a photograph cannot be taken as intended by the user.

In order to solve the above problems, an exposure control device according to the present invention provides:
An LED control unit (4) for controlling turning on / off of the LED (2) by an operation of the external SW (3), the automatic focus control unit (9) for performing automatic focus control, and an automatic exposure control unit for performing automatic exposure control (12)
The LED lighting state detection means (4, 21) for detecting whether the LED is turned on / off during automatic focus control and the automatic focus control unit perform photometry when the subject is focused, and hold the photometric value until shooting. A metering mode that controls exposure during shooting using the metering value
When shooting in the metering mode, if the lighting state of the LED at the metering timing just before imaging is different from the lighting state of the LED at the time of focusing, re-metering is performed and imaging is performed under the exposure condition based on the re-metering. In addition, when the lighting state of the LED at the photometric timing immediately before imaging is the same as the lighting state of the LED at the time of focusing, photographing is performed under the exposure condition of the photometric value at the time of focusing.

  According to the exposure control device of the present invention, in a camera system provided with LED illumination as auxiliary light for autofocusing as well as shooting illumination, the external SW can be turned on at a timing intended by the user. It is possible to perform the control with the optimum exposure under any condition of the lighting state and the photometry mode. That is, for example, in macro photography, the user can always take pictures under appropriate exposure conditions while turning on the LED illumination at any time according to the conditions of the subject.

Overall configuration diagram showing an embodiment of the present invention Time chart showing an embodiment of the present invention The flowchart which shows embodiment of this invention

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  The configuration of the embodiment of the present invention will be described with reference to FIG. Here, an interchangeable lens type single-lens reflex camera will be described as an example.

  In FIG. 1, 1 to 4 are hardware configured on the lens side, and 6 to 22 are hardware configured on the camera body side. Reference numeral 1 denotes a photographing lens, and reference numeral 2 denotes an LED illumination device, which is an example constituted by two chips here. Reference numeral 3 denotes an external SW for lighting the LED, which is used to request an interrupt to the microcomputer 4 when operated by the user. The SW is designed to repeatedly turn on / off each time the SW is pressed. is there. The microcomputer 4 performs lighting control of the LED lighting device 2 in response to a request from the external SW 3.

  Reference numeral 6 denotes a main mirror disposed at 45 degrees with respect to the optical axis, which is operated at the time of imaging and is housed in a position that does not affect the imaging optical axis. 7 is a sub mirror, 8 is a spectacle lens for AF, and 9 is an AF sensor. When the main mirror is in the down position, the light passes through the main mirror 6, is reflected by the sub mirror 7, and forms an image on the AF sensor 9 through the eyeglass lens 8. 13 is the front curtain of the focal plane shutter, and 14 is the rear curtain of the focal plane shutter. Reference numeral 15 denotes an image sensor, and here, a CMOS sensor is assumed. The subject light is imaged on the image sensor 15 via the imaging lens 1, the front curtain 13 of the focal plane shutter, and the rear curtain 14 of the focal plane shutter.

  In addition to the imaging optical system, there is a photometric optical system that reflects on the main mirror 6 and forms an image on the photometric sensor 12 through the pentaprism 10 and further through the photometric lens 11. The video imaged by the imaging device 15 is taken into the memory 19 after being processed by the DSP 18 via the AD converter 16. Reference numeral 17 denotes a timing generator. The DSP 18 controls the timing generator 17 so that the DSP 18, the image sensor 15, and the AD converter 16 are synchronously controlled. Reference numeral 20 denotes an external liquid crystal, which is a member that displays an image captured by the image sensor 15 to the outside.

  Reference numeral 21 denotes a microcomputer for controlling the entire camera, and the external SW 22 has a two-stage Push-type SW structure. When the user makes a photographing request by the first-stage Push operation, the camera is in an operation ready for photographing. Become. Specifically, the microcomputer 21 determines the exposure for photographing from the output result of the photometric sensor 12.

  Further, the microcomputer 21 communicates with the lens-side microcomputer 4 based on the result of the AF sensor 9, the microcomputer 4 receives a request from the camera-side microcomputer 21, and the microcomputer 4 drives the focus of the imaging lens 1. Next, an imaging operation is performed by the second-stage Push operation of the external SW 22. In response to this second stage photographing request, the microcomputer 4 performs the lens aperture operation, which is omitted here, and operates the focal plane shutters 13 and 14 so as to obtain the predetermined exposure. The subject image is formed on the image sensor 15, that is, the exposure state is performed for the predetermined shutter time. At the same time, the microcomputer 21 issues an imaging command to the DSP 18, and the DSP 18 controls the TG 17 to control the imaging device 15 and the AD converter 16, and records the captured image in a memory such as 19 DRAM via the DSP 18. Further, the DSP 18 performs image processing on the image recorded in the DRAM 19 and displays the image on the external liquid crystal 20 or records it on an external memory such as an SD card, which is omitted here.

  Next, the operation of the embodiment of the present invention will be described with reference to FIGS.

  In FIG. 2, in the operation of repeatedly turning on / off each time the user presses the external SW 3 for turning on the LED lighting, the LED lighting is turned on when the user presses the first stage of the external SW 22 for shooting request (shooting preparation state). Is a time chart in a case where the LED illumination is turned off when the user presses the second stage of the external SW 22 that is a photographing request (imaging state). That is, this is a timing example in which the lighting state of the LED illumination is different between AF focusing and imaging, and the exposure at the time of final imaging is likely to be incorrect.

  FIG. 3 shows a flowchart of the specific operation, and the specific operation will be described with reference to FIGS.

  First, the user depresses the external SW 3 (# 100). By this operation, an interrupt request is generated to the microcomputer 4 (# 101). Next, the microcomputer 4 turns on the LED illumination 2 (# 102). At the same time, the microcomputer 4 notifies the camera-side microcomputer 21 of the lighting state of the LED illumination 2 (# 103). Next, when the photometry mode of the camera is set to the photometry mode in which the photometry value is locked and the photometry is performed when the ONE_SHOT AF is in focus, the operations of steps # 105 to # 114 are performed. When the photometric value is set to the photometric mode in which photographing is performed based on the photometric value immediately before imaging, the operations of steps # 120 to # 128 are performed.

  First, when the metering mode is set in which the metering value is locked and shooting is performed when the ONE_SHOT AF is in focus, the user enters the shooting preparation operation by pressing the first step of SW22 (# 105), and the microcomputer 21 Communicates with the microcomputer 4 based on the output result of the AF sensor 9 to operate the imaging lens 1 to perform focus driving (# 106). The microcomputer 21 calculates a photometric value from the output results of the twelve photometric sensors and stores the state (# 107). In this state, when the user presses the LED illumination button 3 (# 108), the LED is controlled to be turned off (# 109). At the same time, the microcomputer 21 on the camera side is notified of the turn-off state (# 110). If the user depresses the second stage of the external SW 22 for which photographing is requested at this timing (# 111), the microcomputer 21 determines that the lighting state of the LED illumination is different from the timing at which the photometric value is stored and the time of imaging. (# 112), the photometric sensor 12 performs the photometric operation again (# 113), and controls the open / close time of the focal plane shutters 13 and 14 and the aperture on the lens side so that the exposure is based on the result. Shooting is performed (# 114).

  On the other hand, if the user does not press the lighting button after the result of calculating the photometric value in # 107, the flow is # 112, and the LED lighting state is the same in the photographing preparation state and the photographing request. Without taking the picture, the open / close time of the focal plane shutters 13 and 14 and the aperture on the lens side are controlled so that the exposure is based on the result of the photometric value (# 107) stored in the shooting preparation stage (##). 114).

  Next, when the light value is set to the metering mode in which photographing is performed based on the metering value immediately before imaging, when the user presses the first step of SW22 (# 120), the photographing preparation operation is started. 21 communicates with the microcomputer 4 from the output result of the AF sensor 9 to operate the imaging lens 1 to perform focus driving (# 121). The microcomputer 21 calculates a photometric value from the output results of the 12 photometric sensors. Next, in this state, when the user presses the LED illumination button 3 (# 123), the LED is controlled to be turned off (# 124). Simultaneously, the microcomputer 21 on the camera side is notified of the light-off state (# 125). When the user depresses the second step of the external SW 22 that is required for photographing at this timing (# 126), the microcomputer 21 performs re-photometry with the photometric sensor 12 (# 127), and exposure is based on the result. In addition, the open / close time of the focal plane shutters 13 and 14 and the lens-side aperture are controlled to perform photographing (# 128).

  As described above, in the mode in which the metering value at the time of AF focusing is locked until imaging is performed, when the user changes the lighting state of the LED illumination between AF focusing and imaging as described above. Also, an example of an operation that enables shooting with an appropriate exposure amount is shown.

1 imaging lens, 2 LED lighting, 3 LED lighting SW, 4 microcomputer on the lens side,
6 Main mirror, 7 Sub mirror, 8 AF glasses lens, 9 AF sensor,
10 pentaprism, 11 photometric lens, 12 photometric sensor,
13 Focal plane shutter front curtain, 14 Focal plane shutter rear curtain,
15 image sensor, 16 AD converter, 17 timing generator,
18 DSP, 19 memory, 20 external liquid crystal, 21 microcomputer on the camera side,
22 Two-stage external SW, 30 LED lighting SW signal, 31 LED lighting signal,
32 External SW22 first stage signal, 33 External SW22 second stage signal,
34 ONE SHOT focusing timing signal, 35 metering timing signal,
36 Imaging timing signal

Claims (1)

An LED control unit (4) for controlling turning on / off of the LED (2) by operating the external SW (3), an automatic focus control unit (9) for performing automatic focus control, and an automatic exposure control unit (for performing automatic exposure control) 12)
The LED lighting state detection means (4, 21) for detecting whether the LED is turned on / off during automatic focus control and the automatic focus control unit perform photometry when the subject is focused, and hold the photometric value until shooting. A metering mode that controls exposure during shooting using the metering value
When shooting in the metering mode, if the lighting state of the LED at the metering timing just before imaging is different from the lighting state of the LED at the time of focusing, re-metering is performed and imaging is performed under the exposure condition based on the re-metering. In addition, when the lighting state of the LED at the time of photometry immediately before imaging is the same as the lighting state of the LED at the time of focusing, the exposure control device performs photographing under the exposure condition of the photometric value at the time of focusing. (FIG. 1).