JP2008298941A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus equipped with a plurality of light emitting parts for performing flash light emission, which picks up an image free from irregular brightness even when the imaging apparatus does not face a subject and is tilted obliquely when picking up the image of a plane subject by using the imaging apparatus. <P>SOLUTION: A center area for detecting a brightness level at the center part and a plurality of periphery areas for detecting the brightness level corresponding to the respective light emitting parts are provided in a display. The imaging apparatus has a control means which detects the brightness levels of the center area and the periphery areas respectively after acquiring an image by image pickup by making the plurality of light emitting parts emit light simultaneously to a predetermined subject, and controls to prolong the light emitting time of the light emitting parts so that the brightness level in the periphery area where the brightness level is low becomes the brightness level in the center area, and shortens the light emitting time of the light emitting parts so that the brightness level in the periphery area where the brightness level is high can be the brightness level in the center area. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus including a plurality of light emitting units that perform flash light emission.

  Since most digital cameras are equipped with a light emitting unit that emits flash light, it is possible to easily take an image even in a dark room. However, since the distance between the imaging lens and the light emitting unit is short in a digital camera equipped with a light emitting unit, when a person is placed near the wall and imaged, the shadow of the person on the wall appears on one side of the person A black outline may result in an unsightly image.

  As a countermeasure in such a case, a digital camera including two light emitting units, that is, an imaging device is disclosed in the patent publication. According to this publication, two light emitting units are separately emitted to capture an image, and two image data are combined with priority given to data having higher luminance than the two image data to generate one image. To do. (See Patent Document 1).

Further, for example, a tooth may be imaged during tooth treatment or tooth cosmetic surgery. In this case, since close-up photography is performed at a distance of several tens of centimeters, when light is emitted by only one light emitting unit as in the past, images are taken on the side where the light emitting unit is located and the side where there is no light emitting unit with the imaging lens as the center. Since the brightness of the teeth is different, an accurate diagnosis cannot be made. Therefore, particularly when close-up photography is performed, it is desirable that at least one light emitting unit is provided on each of the left and right sides of the imaging lens.
JP-A-11-196325

  As described above, in particular, when performing close-up photography, it is desirable to provide an imaging apparatus that can provide at least one light emitting unit on each of the left and right sides of the imaging lens and can simultaneously emit light from the left and right.

  The following problems may occur when a relatively flat subject is imaged using such an imaging device. In other words, the imaging lens of the imaging apparatus cannot be directly opposed to a flat subject due to restrictions on the imaging location and the like, and imaging may be performed from an oblique direction. In addition, a person who is unfamiliar with the camera may take an image from an oblique direction even if there is no restriction on the imaging location. For example, when using an imaging device in which the light emitting units are arranged on the left and right of the imaging lens and taking an image obliquely, the distance between the right light emitting unit and the subject is different from the distance between the left light emitting unit and the subject. Come. Normally, the light emission amounts from the left and right light emitting units are set to be equal, so the imaging area of the subject that is mainly irradiated with flash light emitted from the light emitting unit far from the subject is underexposed, The imaging region of the subject that is mainly irradiated with flash light emitted from the light emitting unit closer to the subject is overexposed, and the captured image has uneven brightness on the left and right.

  The present invention has been made in view of such a problem. When a planar subject is imaged using an imaging device including a plurality of light emitting units that perform flash emission, the imaging device faces the subject. An object of the present invention is to propose an imaging device that can capture an image that does not cause uneven brightness even if it is inclined obliquely.

  An imaging apparatus according to the present invention is an imaging apparatus including a plurality of light emitting units that emit flash light. A central region that detects a brightness level of a central part in a screen and a brightness level corresponding to each of the light emitting units. A plurality of peripheral areas to be detected are provided, and a plurality of the light-emitting units are simultaneously emitted to a predetermined subject to obtain an image and detect brightness levels of the central area and the peripheral area, For the peripheral area with a low brightness level, the light emission time of the light emitting unit is extended so as to be the brightness level of the central area, and for the peripheral area with a high brightness level, the brightness level of the central area is reached. Thus, it has a control means for controlling to shorten the light emission time of the light emitting unit.

  The imaging apparatus of the present invention is an imaging apparatus having a plurality of light emitting units that perform flash emission, and has a plurality of ranging areas corresponding to the light emitting units in the periphery of the screen, for each ranging area. A distance measuring means for performing distance measurement, and a control for controlling the distance measurement means to change the light emission time of each light emitting section so as to obtain an appropriate exposure according to the subject distance measured in each distance measurement area. Means.

  According to the imaging device of the present invention, when a planar subject is imaged with a plurality of light emitting units that perform flash emission, even if the imaging device is not facing the subject and is inclined obliquely, Since the flash light is corrected, it is possible to capture an image with no uneven brightness. Therefore, the effect is particularly great when close-up photography is performed, and for example, teeth can be imaged with uniform brightness at the time of tooth treatment or tooth cosmetic surgery, and accurate diagnosis is possible.

  First, an example of the imaging apparatus of the present invention will be described with reference to FIG. FIG. 1 is an external view of an imaging device, FIG. 1A is a top view of the imaging device, and FIG. 1B is a front view of the imaging device.

  As shown in FIG. 1B, an imaging lens 11 that is a zoom lens is disposed in the center of the front of the imaging device 1. A light emitting unit 12 that performs flash emission is disposed on the right side of the imaging lens 11, and a light emitting unit 13 that performs flash emission is also disposed on the left side of the imaging lens 11.

  As shown in FIG. 1A, a power button 14 for turning on / off the power of an electronic circuit in the imaging device 1 is disposed on the upper surface of the imaging device 1, and a release button 15 is disposed next thereto. ing.

  A mode dial 16 for performing a normal imaging mode, a moving image imaging mode, a playback mode, a setup mode, a print mode, and the like is disposed on the rear surface of the imaging apparatus 1, and a zoom button 17 for performing zoom-up and zoom-down is disposed adjacent thereto. Has been. Although not shown, a menu button, a selection button including a four-way switch, a set button, a display unit including an LCD and displaying a captured image are disposed. Various menus are also displayed on the display unit with the menu button, selected with the selection button, and confirmed with the set button. An erasing button for erasing the captured and recorded image is also arranged.

  Although not shown, a tripod base, a connection terminal of an AC adapter, a connection terminal for connection to an external device, and the like are arranged on the bottom surface of the imaging device 1.

  Although not shown, the side of the image pickup apparatus 1 includes a battery chamber cover for storing a battery serving as a power source for an electronic circuit in the image pickup apparatus 1, a memory card chamber cover for storing a memory card for image recording, and the like. Has been placed.

  Next, a block diagram of main components of the imaging apparatus 1 will be described with reference to FIG.

  The light image of the subject is formed on the CCD 22 which is an image pickup element by the image pickup lens 21 corresponding to the image pickup lens 11. Of course, a CMOS may be used instead of the CCD. The CCD 22 is a color area sensor in which red light (R), green light (G), and blue light (B) color transmission filters are arranged in units of pixels, and an optical image of a subject is converted into R, G, and B color components. Photoelectric conversion to image signal.

  The image signal is converted into a digital signal by the A / D converter 23 through a CDS circuit and AGC circuit (not shown).

  Subsequently, the image signal is subjected to image processing such as black level correction and pudging correction in the image processing unit 24 and is recorded in the recording unit 25. The image signal is displayed as a visible image on the display unit 26 formed of an LCD.

  The CPU 27 is a microcomputer that controls each circuit. The CPU 27 drives the AE / AF circuit 28 (ranging means) to set the diaphragm attached to the imaging lens 21 in accordance with the subject brightness, and the imaging lens 21 so that the optical image of the subject is focused on the CCD 22. AF control is performed to move the image according to the subject distance.

  The CPU 27 is connected to a storage unit 29 including a RAM and switches S1 and S2. The switch S1 is turned on when the release button 15 is pressed halfway, and the switch S2 is turned on when the release button 15 is fully pressed.

  Further, the CPU 27 controls the strobe control circuit 31, and the strobe control circuit 31 controls the strobe circuit 40 to perform flash emission.

  The strobe circuit 40 includes one booster circuit 41 and two light emitting circuits 50 and 60. Light emitting circuits 50 and 60 are xenon tubes 51 and 61 that emit strobe light (flash light), trigger circuits 52 and 62 that start light emission of the xenon tubes 51 and 61, and switching elements that control the light emission time of the xenon tubes 51 and 61. IGBTs 53 and 63, and main capacitors 54 and 64 for charging electric charges for emitting strobe light. The trigger circuits 52 and 62 include a trigger coil, a trigger capacitor, and a thyristor.

  The strobe light from the light emitting circuit 50 is emitted from the light emitting unit 12, and the strobe light from the light emitting circuit 60 is emitted from the light emitting unit 13.

  In response to a command from the CPU 27, the strobe control circuit 31 operates the booster circuit 41 to boost the power supply voltage to a high voltage, and charges the main capacitors 54 and 64 and the trigger capacitor in advance. When imaging is started, the strobe control circuit 31 turns on the IGBTs 53 and 63 according to a command from the CPU 27. Subsequently, when the strobe control circuit 31 turns on the thyristors of the trigger circuits 52 and 62 and applies a high voltage to the secondary side of the trigger coil by the discharge of the trigger capacitor, the xenon tubes 51 and 61 are charged by the charges of the main capacitors 54 and 64. Start flashing. If the strobe control circuit 31 turns off the IGBTs 53 and 63 according to a command from the CPU 27 while the xenon tubes 51 and 61 emit light, the light emission of the xenon tubes 51 and 61 stops.

  The CPU 27 controls the strobe control circuit 31 to turn off the IGBTs 53 and 63 based on the imaging distance measured by the AE / AF circuit 28. That is, if the imaging distance is short, the timing for turning off the IGBTs 53, 63 is advanced to reduce the amount of light emitted from the xenon tubes 51, 61, and if the imaging distance is long, the timing for turning off the IGBTs 53, 63 is delayed. In this way, the amount of light emitted from the xenon tubes 51 and 61 is increased so that the captured image is properly exposed.

  FIG. 3 shows a timing chart of the light emitting circuit 50.

  When light is emitted from the light emitting unit 12, the CPU 27 operates the strobe circuit control circuit 31 to turn on the IGBT 53 of the light emitting circuit 50. Subsequently, when the thyristor of the trigger circuit 52 is turned on, the xenon tube 51 starts to emit light. If the IGBT 53 is turned off after a predetermined time corresponding to the imaging distance has elapsed, the light emission of the xenon tube 51 is stopped.

  The same applies when the light emitting circuit 60 is operated to emit light from the light emitting unit 13.

  Here, during normal imaging, the normal imaging mode is selected with the mode dial 16 shown in FIG. 1, and both the xenon tubes 51 and 61, that is, the light emitting units 12 and 13 are caused to emit light at the same time for imaging. In this way, when the light emitting units 12 and 13 are caused to emit light simultaneously, the amount of each light emission may be ½ compared to the case where one light emitting unit emits light.

  Therefore, when there is a wall or the like behind the subject, the shadow reflected on the wall is reduced. In addition, when one light emitting unit emits light during close-up, the left and right brightness on the imaging screen is different and uneven, but when two light emitting units emit light, the left and right brightness on the imaging screen is uniform. And no unevenness.

  When the two light emitting units emit light at the same time, there are advantages as described above. However, when imaging a planar subject, the imaging device is not facing the subject and the right side The distance between the light emitting unit and the subject is different from the distance between the left light emitting unit and the subject. Normally, the amount of light emitted from the left and right light emitting units is set to be equal, so the area captured by the light emitting unit far from the subject is underexposed and the light emitting unit near the subject is underexposed. The captured area is overexposed and the captured image has uneven brightness on the left and right.

  In order to solve this problem, the imaging apparatus automatically adjusts the light emission amounts of the two light emitting units to correct the light emission amounts to be substantially equal.

In the following, two embodiments for automatically correcting the light emission amounts of the two light emitting units will be described.
[First Embodiment]
The first embodiment will be described with a focus on the flowchart of FIG.

  When imaging, the imaging mode is set, and the composition of the subject is determined on the display unit 26 (S101). Subsequently, when the release button 15 is pressed halfway and the first-stage switch S1 is turned on (Y in S102), the CPU 27 that detects this controls the AE / AF circuit 28 to perform photometry and distance measurement. (S103), and the flash control circuit 31 is controlled to cause the xenon tubes 51 and 61 to simultaneously emit pre-light (S104). That is, the strobe light is simultaneously pre-flashed from the light emitting units 12 and 13. In the pre-light emission, not all the charges of the main capacitors 54 and 64 are emitted, but, for example, the light emission amount may be about 1/30 of the main light emission. Therefore, the amount of light is not enough for proper exposure, but this is sufficient for comparison of brightness levels as will be described later.

  In addition, another light source such as an LED may be provided to emit light during pre-emission.

  Then, the image acquired by the pre-flash is recorded in the recording unit 25, and the CPU 27 detects and compares the brightness level of the central region in the image and the brightness level of the peripheral region corresponding to each light emitting unit. (S105).

  Specifically, this will be described with reference to FIG. FIG. 5 is a diagram of a screen imaged on the CCD 22 when the pre-flash is imaged.

  On the imaged screen 5, a central area 5a, a peripheral area 5b, and a peripheral area 5c are set. The central region 5a is a central region of an image that is equally irradiated with strobe light from both the light emitting units 12 and 13, and the peripheral region 5b is a region that is mainly irradiated with strobe light from the light emitting unit 12, and the peripheral region. Reference numeral 5c denotes a region where the strobe light from the light emitting unit 13 is mainly irradiated.

  The CPU 27 extracts the brightness levels of the central area 5a, the peripheral area 5b, and the peripheral area 5c. Specifically, the brightness of all the pixels in each region is divided into 8 bits of 0 to 255, and the average value of brightness is calculated. Then, this value is stored in the storage unit 29. Subsequently, the CPU 27 extracts the brightness level of each area from the storage unit 29, and compares the brightness levels of the peripheral area 5b and the peripheral area 5c with the brightness level of the central area 5a.

  Note that it is not always necessary to average the brightness levels of the pixels at the center of the image, and a median value or the like may be used as long as the value represents the brightness level.

  For example, as illustrated in FIG. 6, it is assumed that the imaging apparatus 1 is tilted so that the subject distance is far from the light emitting unit 12 and the light emitting unit 13 is closer to the planar subject 3. In FIG. 6, as for the oblique line between the imaging device 1 and the subject 3, the solid line indicates the incident light path to the imaging lens, and the broken line indicates the irradiation light path of the strobe light from the light emitting units 12 and 13. Since the distance between the light emitting unit 13 and the subject 3 is short, the strobe light is strongly irradiated by the subject 3, and on the screen 5 imaged on the CCD 22, the brightness level of the peripheral region 5c is higher than the brightness level of the central region 5a. Get higher. On the other hand, since the distance between the light emitting unit 12 and the subject 3 is long, the strobe light is weakly irradiated by the subject 3, and on the screen 5, the brightness level of the peripheral region 5b is lower than the brightness level of the central region 5a.

  Since the subject image is reversed up and down and left and right on the screen 5 formed on the CCD 22, for example, the subject on the right side forms an image on the left side on the screen 5.

  As described above, when there is a difference between the brightness level of the peripheral area 5b and the peripheral area 5c and the brightness level of the central area 5a (Y in S106), the ON times of the IGBTs 53 and 63 in the light emitting circuit 60, that is, the IGBT 53 , 63 is changed in time until it is turned off.

  As described above, when the brightness level of the peripheral area 5c is higher than the brightness level of the central area 5a on the screen 5 imaged on the CCD 22, the CPU 27 emits light. The on-time of the IGBT 53 is lengthened so that the strobe light from the light-emitting circuit 50 corresponding to the unit 12 becomes strong, and the on-time of the IGBT 63 is shortened so that the strobe light from the light-emitting circuit 60 corresponding to the light-emitting unit 13 becomes weak. To control.

  Note that the amount of change in the ON time of the IGBTs 53 and 63 corresponding to the value of the difference in brightness level is stored in advance in the storage unit 29 as a table.

  After the ON times of the IGBTs 53 and 63 are corrected in this way (S107), the fact that the control of the light emission amount has been completed is displayed on the display unit 26 (108).

  Subsequently, when the release button 15 is further pressed, the switch S2 in the second stage is turned on (Y in S109), and the CPU 27 controls the strobe control circuit 31 so that the xenon tube can be used with an amount of light that provides an appropriate exposure according to the subject distance. Although the main light emission is performed from 51 and 61 (S110), the ON times of the IGBTs 53 and 63 are corrected as described above. In this state, the image is recorded in the recording unit 25 (S111). Therefore, even if the subject 3 is inclined, the brightness level of the image is recorded uniformly on the screen 5.

  When there is no difference between the brightness level of the peripheral area 5b and the peripheral area 5c and the brightness level of the central area 5a (N in S106), the on-time of the IGBTs 53 and 63 is not corrected, and the display unit 26 Without display, the switch S2 is turned on (Y in S109), normal light emission control is performed (S110), and an image is recorded (S111).

Although the light emitting units 12 and 13 and the light emitting circuits 50 and 60 are two sets in the above embodiment, depending on the case, the light emitting units are provided on the top, bottom, left and right, and four sets of light emitting circuits are provided. You may make it respond | correspond to the inclination of a to-be-photographed object.
[Second Embodiment]
A second embodiment will be described with a focus on the flowchart of FIG.

  When imaging, the imaging mode is set, and the composition of the subject is determined on the display unit 26 (S201). Subsequently, when the release button 15 is pressed halfway and the first-stage switch S1 is turned on (Y in S202), the CPU 27 detecting this controls the AE / AF circuit 28 to perform photometry and distance measurement. (S203).

  Here, as shown in FIG. 8, a distance measurement area 7a and a distance measurement area 7b are set on the screen 7 imaged on the CCD 22, and distance measurement is performed in each of these areas.

  Therefore, for example, as shown in FIG. 6 of the first embodiment, the imaging apparatus 1 is tilted so that the subject distance is far from the light emitting unit 12 and the light emitting unit 13 is closer to the planar subject 3. Then, the subject distance measured in the distance measurement area 7a is detected as a long distance, and the subject distance measured in the distance measurement area 7b is detected as a short distance.

  As described above, if there is a difference in the distance measurement results between the distance measurement area 7a and the distance measurement area 7b (Y in S204), the ON times of the IGBTs 53 and 63 are set so as to obtain an appropriate exposure according to the detected object distance. Correction is performed (S205). The ON times of the IGBTs 53 and 63 corresponding to the subject distance are stored in advance in the storage unit 29 as a table, and the CPU 27 calls this to control the flash control circuit 31.

  Then, the display unit 26 displays that the control of the light emission amount has ended (206).

  Subsequently, when the release button 15 is further pressed, the second-stage switch S2 is turned on (Y in S207), and the CPU 27 controls the strobe control circuit 31 and corrects the on-times of the IGBTs 53 and 63 based on the xenon tube. The light is emitted from 51 and 61 (S208), the image is taken, and the image is recorded in the recording unit 25 (S209). Therefore, even if the subject 3 is inclined, the brightness level of the image is recorded uniformly on the screen 5.

  If there is no difference in the distance measurement results between the distance measurement area 5a and the distance measurement area 5b (N in S204), the ON times of the IGBTs 53 and 63 are not corrected and are not displayed on the display unit 26. When the switch S2 is turned on (Y in S207), normal light emission control is performed (S208), and an image is recorded (S209).

  In the above embodiment, the distance measurement area 7a and the distance measurement area 7b, the light emitting units 12 and 13, and the light emission circuits 50 and 60 are each two sets. It is also possible to provide four sets of light emitting circuits on the top, bottom, left, and right so as to cope with the inclination of the subject on the top, bottom, left, and right.

It is an external view of an imaging device. Block diagram of main components of imaging device It is a timing chart which shows light emission of a light emission part. It is a flowchart explaining 1st Embodiment. It is a figure of the center area | region and peripheral area in the imaged screen. It is a top view of the state which installed the imaging device inclining with respect to the to-be-photographed object. It is a flowchart explaining 2nd Embodiment. It is a figure of the ranging area in the imaged screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up device 3 Subject 5, 7 Screen 5a Center area 5b, 5c Peripheral area 7a, 7b Distance measuring area 11, 21 Imaging lens 12, 13 Light emission part 15 Release button 22 CCD
25 Recording unit 26 Display unit 27 CPU
28 AE / AF circuit 29 Storage unit 31 Strobe control circuit 40 Strobe circuit 41 Booster circuit 50, 60 Light emitting circuit 51, 61 Xenon tube 52, 62 Trigger circuit 53, 63 IGBT
54, 64 Main capacitor S1, S2 Switch

Claims (8)

In an imaging device including a plurality of light emitting units that perform flash emission,
Provide a central area for detecting the brightness level of the central part in the screen, and a plurality of peripheral areas for detecting the brightness level corresponding to each of the light emitting parts,
A plurality of the light emitting units emit light at the same time with respect to a predetermined subject to obtain an image, and then detect brightness levels of the central region and the peripheral region, respectively, and the peripheral region having a low brightness level. Extends the light emission time of the light emitting unit so as to be the brightness level of the central region, and for the peripheral region where the brightness level is high, the light emission time of the light emitting unit is set so as to be the brightness level of the central region. An imaging apparatus comprising control means for controlling to shorten the image pickup apparatus. The imaging apparatus according to claim 1, wherein the peripheral region corresponding to the light emitting unit is provided in a region in a screen for imaging a subject mainly irradiated with flash light emitted from a predetermined light emitting unit. The control means performs pre-light emission with a small amount of light by turning on the first-stage switch when the release button is pressed to change the light emission time of each light emitting unit, and turns on the subject by turning on the second-stage switch when the release button is pressed. 3. The image pickup apparatus according to claim 1, wherein control is performed so as to perform flash light emission at an appropriate exposure according to a distance. In an imaging device including a plurality of light emitting units that perform flash emission,
A plurality of ranging areas each corresponding to the light emitting unit in the periphery of the screen, and ranging means for measuring the distance for each ranging area;
Control means for controlling the light emission time of each light emitting unit to change so that the distance measurement means has an appropriate exposure according to the subject distance measured in each of the distance measurement areas;
An imaging apparatus comprising: 5. The imaging apparatus according to claim 4, wherein the distance measuring area corresponding to the light emitting unit is provided in an area in a screen for imaging a subject mainly irradiated with flash light emitted from a predetermined light emitting unit. . The distance measuring means changes the light emission time of each light emitting unit based on the result of distance measurement performed by turning on the first-stage switch by pressing the release button, and by turning on the second-stage switch by pressing the release button. 6. The image pickup apparatus according to claim 4, wherein control is performed so as to perform flash light emission at an appropriate exposure according to a subject distance. The imaging apparatus according to claim 1, wherein a light emission time of the light emitting unit is changed by changing a time until the switching element is turned off. The image pickup apparatus according to claim 1, further comprising display means for displaying that the control of the light emission amount has been completed.

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