JP2005295475A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device for suppressing small-stop diffraction caused by an iris as much as possible and preventing an object from becoming unnaturally dark. <P>SOLUTION: The imaging device is provided with: an iris for controlling the quantity of light transmitted through an optical imaging system; an image pickup element for storing and photoelectric-transducing the transmitted light; a photometric value generating means for dividing a imaged picture into a plurality of pictures, gating a video luminance signal and integrating a video luminance signal corresponding to the inside of a designated region on the imaged picture to determine the average quantity of light; an aperture size detecting means for detecting an aperture size of the iris; a coefficient generating means for generating a coefficient corresponding to the aperture size of the iris; and a photometric value converting means for converting a photometric value by multiplying the photometric value generated by the photometric value generating means by the coefficient generated by the coefficient generating means. The imaging device controls the iris in accordance with the photometric value generated by the photometric value converting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus such as a camera-integrated VTR.

  Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 2004-61740, means for automatically performing exposure control in an imaging apparatus such as a video camera has been devised. FIG. 5 is a block diagram of the conventional example, FIG. 6 is a supplementary diagram of the conventional example, FIG. 7 is a flowchart of the conventional example, FIG. 8 is a supplementary example of the conventional example, and FIG. This will be described below.

  In the block diagram of the conventional example of FIG. 5, 501 is an iris that adjusts the amount of incident light, 502 is an image sensor such as a CCD that photoelectrically converts an image whose amount of light has been adjusted by the iris 501 and converts it into a video signal, 503 Is an AGC circuit that gives a gain to the video signal output from the imaging element 502, 504 is a camera signal processing circuit that converts the video signal into a standardized video signal by performing predetermined signal processing, and 505 is on the imaging screen Is divided into a plurality of screens and a video luminance signal obtained from the AGC circuit 503 is multiplied by a plurality of gates to extract an image signal corresponding to an arbitrary region, and the video luminance signal corresponding to the designated region on the imaging screen is integrated. The luminance signal detection circuit 506 for obtaining the average light quantity respectively controls the AE from the plurality of photometric values detected by the luminance signal detection circuit 505. A photometric value calculation circuit 507 for calculating a photometric value for performing the AE control by actually controlling the gains of the iris 501 and the AGC circuit 503 using the photometric value generated by the photometry value calculation circuit 506; This is an AE control signal arithmetic circuit for performing The configuration is as described above.

  FIG. 6 is a specific diagram when the imaging screen is divided into a plurality of screens in the luminance signal detection circuit 505 in the block diagram of the conventional example of FIG.

  A gates the center of the screen and integrates the video luminance signal, and the average amount of light obtained in this area is Ys3.

  B gates the periphery of the screen and integrates the video luminance signal, and the average light quantity obtained in this area is Ys2.

  C gates the top of the screen and integrates the video luminance signal, and the average light quantity obtained in this area is Ys1.

  FIG. 7 is a flowchart showing the photometric value calculation processing contents in the luminance signal detection circuit 505 and photometric value calculation circuit 506 in the block diagram of the conventional example of FIG.

  701... Ys1 is a photometric value at the upper part of the screen (C in FIG. 6) detected by the luminance signal detection circuit 505.

  702... Ys2 is a photometric value of the peripheral portion of the screen (portion B in FIG. 6) detected by the luminance signal detection circuit 505.

  703... A photometric value at the center of the screen (portion A in FIG. 6) detected by the luminance signal detection circuit 505 is Ys3.

  704... Multiplying Ys1, Ys2, and Ys3 generated by 701, 702, and 703 by a predetermined center-weighted average metering ratio (α: β: γ), and adding each of them. Calculate the photometric value.

  The flow is as described above.

  FIG. 8 illustrates the relationship between the illuminance of the subject and the AE control parameters when AE control is performed in the AE control signal arithmetic circuit 507 in the block diagram of the conventional example of FIG. There are two types of AE control parameters, the gain by the iris 501 and the AGC circuit 503. The iris 501 is used for the AE control parameter when the subject is bright, and the gain by the AGC circuit 503 is used for the AE control parameter when the subject is dark. This is illustrated.

  FIG. 9 shows the target value of exposure when AE control is performed in the AE control signal arithmetic circuit 507 in the block diagram of the conventional example of FIG. As can be seen from FIG. 9, it is shown that the exposure state is always constant regardless of the brightness of the subject illuminance.

  Next, specific operations will be described with reference to FIGS. 5, 6, 7, 8, and 9.

  An optical image is photoelectrically converted by the image sensor 502 via the iris 501. The video signal output from the image sensor 502 is input to the AGC circuit 503, has a predetermined gain, and is sent to the camera signal processing circuit 504.

The video luminance signal for controlling exposure is input to the luminance signal detection circuit 505 using the video luminance signal before being input to the camera signal processing circuit 504. The luminance signal detection circuit 505 multiplies the video luminance signal by a plurality of gates and integrates the video luminance signal corresponding to the designated area on the imaging screen to obtain the average light quantity. For example, the video luminance signal at the center of the screen corresponding to the portion A in FIG. 6 is integrated to obtain the photometric value Ys3 that is the average light amount (flowchart 703 in FIG. 7), and corresponds to the portion B in FIG. The video luminance signal at the periphery of the screen is integrated to obtain a photometric value Ys2 that is the average light amount (flow chart 702 in FIG. 7), and the video luminance signal at the top of the screen corresponding to the portion C in FIG. A photometric value Ys1 that is an average light amount is obtained (flow chart 701 in FIG. 7). Then, the respective photometric values Ys 1, photometric values Ys 2, and photometric values Ys 3 are input to the photometric value calculation circuit 506. In the photometric value calculation circuit 506, the photometric value Ys1 at the top of the screen, the photometric value Ys2 at the periphery of the screen, the photometric value Ys3 at the center of the screen, and the respective photometric values are added at a predetermined ratio. Calculate the value. (FIG. 7 Flowchart 704) In this conventional example, the addition ratio of Ys1, Ys2, and Ys3 is α: β: γ, and the photometric value is Ys = Ys1 × α + Ys2 × β + Ys3 × γ.
I am seeking.

  In the AE control signal calculation circuit 507, the gains of the iris 501 and the AGC circuit 503 are controlled so that the level of the photometry value calculated by the photometry value calculation circuit 506 falls within a predetermined range. Done by things.

  As shown in FIG. 8, when the illuminance of the subject is bright, the gain of the AGC circuit 503 is fixed to 0 dB and the exposure is controlled by the iris 501. On the other hand, when the illuminance of the subject is dark, the iris 501 The exposure is controlled by gain control of the AGC circuit 503 while being fixed to the open end.

  As a result of the AE control by the AE control signal calculation circuit 507, the exposure state is always constant regardless of the brightness of the subject illuminance as shown in FIG.

  As described above, in the conventional imaging apparatus, the target value of the AE control signal calculation circuit 507 is set so that the video level becomes 50 IRE when a white subject is imaged regardless of whether the illuminance of the subject is bright or dark. Therefore, the brighter the subject is outdoors, the more easily the iris diameter of the iris 501 becomes smaller, and as a result, the captured image becomes blurred due to the influence of diffraction. There is. Also, the subject looks very bright, but the imaging result is dark, the impression when the subject is actually viewed and the imaging result are so different that it gives an unnatural impression and the realism is not transmitted is there.

  The present invention has been made in view of the current state of the imaging apparatus as described above, and an object thereof is to prevent the iris 501 from having an aperture diameter as small as possible when the subject is sufficiently bright outdoors or the like. An object of the present invention is to provide an imaging apparatus that controls to suppress a blurring phenomenon due to diffraction as much as possible and prevent an object from becoming unnaturally dark.

  An iris that controls the amount of light transmitted through the imaging optical system, an image sensor that accumulates the transmitted light and performs photoelectric conversion, a screen that divides the image screen into multiple screens, gates the video luminance signal, and designates the image on the image screen A photometric value generating means for integrating an image luminance signal corresponding to the area to obtain an average light amount, an aperture diameter detecting means for detecting the aperture diameter of the iris, and a coefficient corresponding to the aperture diameter of the iris are generated. And a photometric value conversion unit that converts the photometric value by multiplying the photometric value generated by the photometric value generation unit and the coefficient generated by the coefficient generation unit. To do.

  As described above, according to the image pickup apparatus of the present invention, the exposure control is performed using the photometric value obtained by multiplying the photometric value by the correction coefficient determined in advance according to Alice's aperture diameter. When the illuminance is bright, the exposure state is also brighter. In other words, it is possible to suppress the iris aperture diameter from being as small as possible when imaging a bright subject. As a result, the blurring phenomenon caused by diffraction can be suppressed as much as possible, and the subject can be prevented from becoming unnaturally dark, and high-quality subject images can be taken.

  The embodiment of the present invention will be described below with reference to the block diagram of the embodiment of FIG. 1, the flowchart of the embodiment of FIG. 2, the supplementary FIG. 1 of FIG. 3, and the supplementary FIG.

  In the block diagram of the embodiment of FIG. 1, reference numerals 501 to 507 are the same as those of the block diagram 501 to 507 of the conventional example shown in FIG.

  103 is a Hall element for detecting the aperture diameter of the iris 501, 102 is an F value information generation circuit for generating F value information from the output of the Hall element 103, and 101 is generated by the photometric value calculation circuit 506. A photometric value conversion circuit for converting the photometric value by multiplying the photometric value by a coefficient determined in advance according to the F value generated by the F value information generating circuit; and 104, the F value information generating circuit. This is an F value information transmission path for transmitting the output from the photometric value conversion circuit 101. The configuration is as described above.

  FIG. 2 is a flowchart of the luminance signal detection circuit 505, the photometric value calculation circuit 506, and the photometric value conversion circuit 101 shown in the block diagram of FIG. Since 701 to 704 in the flowchart of FIG. 2 embodiment have the same configuration as 701 to 704 of the flowchart of the conventional example of FIG. 7 described in the conventional example, description thereof is omitted here.

  201... A correction coefficient is determined according to the F value generated by the F value information generation circuit 102.

  202... The photometric value Ys ′ is calculated by multiplying the photometric value Ys generated by the photometric value calculating circuit 506 by the correction coefficient determined in 201.

  The flow is as described above.

  Next, a specific operation will be described with reference to FIG. 1, FIG. 2, FIG. 3, and FIG.

  An optical image is photoelectrically converted by the image sensor 502 via the iris 501. The video signal output from the image sensor 502 is input to the AGC circuit 503, has a predetermined gain, and is sent to the camera signal processing circuit 504.

  The video luminance signal for controlling exposure is input to the luminance signal detection circuit 505 using the video luminance signal before being input to the camera signal processing circuit 504. The luminance signal detection circuit 505 multiplies the video luminance signal by a plurality of gates and integrates the video luminance signal corresponding to the designated area on the imaging screen to obtain the average light quantity. For example, the video luminance signal at the center of the screen corresponding to the portion A in FIG. 6 is integrated to obtain a photometric value Ys3 that is the average light amount (FIG. 2 flowchart 703), and corresponds to the portion B in FIG. The video luminance signal at the periphery of the screen is integrated to obtain a photometric value Ys2 that is the average light amount (FIG. 2 flowchart 702), and the video luminance signal at the top of the screen corresponding to the portion C in FIG. A photometric value Ys1 that is an average light amount is obtained (FIG. 2 flowchart 701). Then, the photometric value Ys 1, the photometric value Ys 2, and the photometric value Ys 3 are input to the photometric value calculation circuit 506, respectively. In the photometric value calculation circuit 506, the photometric value Ys1 at the top of the screen, the photometric value Ys2 at the periphery of the screen, the photometric value Ys3 at the center of the screen, and the respective photometric values are added at a predetermined ratio. The value is calculated (flow chart 704 in FIG. 2).

In this embodiment, the addition ratio of Ys1, Ys2, and Ys3 is α: β: γ, and the photometric value is Ys = Ys1 × α + Ys2 × β + Ys3 × γ.
I am seeking.

  Then, Ys generated by the photometric value calculation circuit 506 is input to the photometric value conversion circuit 101.

  On the other hand, the aperture diameter of the iris 501 is detected by the Hall element 103 and input to the F value information generation circuit 102. The F value information generation circuit 102 generates F value information from the output of the Hall element 103 and inputs the F value information to the photometric value conversion circuit 101 via the F value information transmission path 104. In the photometric value conversion circuit 101, a predetermined correction coefficient is determined according to the F value transmitted through the F value information transmission path 104 (FIG. 2 flowchart 201). Then, the photometric value Ys ′ is calculated by multiplying the correction coefficient by the photometric value Ys calculated by the photometric value calculation circuit 506 (flow chart 202 in FIG. 2). Thereafter, the photometric value Ys ′ is input to the AE control signal calculation circuit 507 to perform AE control.

  In the following, a more detailed description will be given using supplementary FIG. 1 of FIG. 3 embodiment and supplementary FIG. 2 of FIG. 4 embodiment.

  FIG. 3 Supplementary Example In FIG. 1, the horizontal axis of FIG. 3 means the illuminance of the subject, the left side of the figure means “when the subject illuminance is bright”, and the right side of the figure means “when the subject illuminance is dark”. This means that the illuminance of the subject changes linearly during these periods. The photometric value Ys (before conversion) 301 is Ys after performing the processing of 704 in the flowchart of the embodiment in FIG. The photometric value Ys (before conversion) 301 is always a constant value regardless of subject illuminance because AE control is always performed. The F value 302 is obtained as a result of performing exposure control by controlling the aperture diameter of the iris 501 by the AE control signal arithmetic circuit 507. It can be seen that the F value changes between F value = 64 and F value = 11 according to the illuminance of the subject. The correction coefficient 303 is a predetermined coefficient determined on a one-to-one basis with the F value 302. The photometric value Ys ′ (after conversion) 304 is generated by multiplying the photometric value Ys (before conversion) 301 by the correction coefficient 303. As can be seen from the figure, when the illuminance of the subject is dark, the photometric value Ys (before conversion) 301 and the photometric value Ys ′ (after conversion) 304 are the same, but when the illuminance of the subject is bright, the photometric value Ys ( It can be seen that the photometric value Ys ′ (after conversion) is smaller than that before (before conversion) 301. In the exposure state (IRE) 305, the exposure state after the photometric value Ys ′ (after conversion) 304 is input to the AE control signal calculation circuit 507 and AE controlled by the iris 501 is changed according to the illuminance of the subject. It is a summary of how it changes. When the aperture diameter of the iris 501 is controlled by the AE control signal calculation circuit 507 using the photometric value Ys ′ (after conversion) 304, the value of the photometric value Ys ′ (after conversion) 304 becomes smaller as the aperture diameter becomes smaller. Thus, as can be seen from the exposure state (IRE) 305, it can be seen that the imaging result, that is, the exposure state, becomes brighter as the subject illuminance increases.

  FIG. 4 Supplementary Example FIG. 2 shows the relationship between the exposure state (IRE) 305 described in the supplementary FIG. 1 example of FIG. 3 and the illuminance of the subject. The exposure state is constant when the subject illuminance is dark, but the exposure state is not constant when the subject illuminance is bright, and the exposure state is increased according to the aperture diameter of the iris 501 in FIG. 1). That is, by changing the exposure state as shown in (1) in the figure when the illuminance of the subject becomes bright, when the illuminance of the subject is bright, the aperture diameter of the iris 501 is controlled so as to be opened as much as possible. It is possible to prevent the phenomenon as much as possible and to capture a high-quality subject image by preventing the subject from appearing unnaturally dark because the imaging result is close to the subject's appearance.

The block diagram of an Example. The flowchart of an Example. Supplementary diagram 1 of the embodiment. Supplementary figure 2 of an Example. The block diagram of a prior art example. Supplementary FIG. 1 of a conventional example. The flowchart of a prior art example. Supplementary figure 2 of a conventional example. Supplementary figure 3 of a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Photometric value conversion circuit 102 F value information generation circuit 103 Hall element 104 F value information transmission path 501 Iris 502 CCD
503 AGC circuit 504 Camera signal processing circuit 505 Luminance signal detection circuit 506 Photometric value calculation circuit 507 AE control signal calculation circuit

Claims (2)

  An iris that controls the amount of light transmitted through the imaging optical system, an image sensor that accumulates the transmitted light and performs photoelectric conversion, a screen that divides the image screen into multiple screens, gates the video luminance signal, and designates the image on the image screen A photometric value generating means for integrating an image luminance signal corresponding to the area to obtain an average light amount, an aperture diameter detecting means for detecting the aperture diameter of the iris, and a coefficient corresponding to the aperture diameter of the iris are generated. And a photometric value conversion unit that converts the photometric value by multiplying the photometric value generated by the photometric value generation unit and the coefficient generated by the coefficient generation unit, the photometric value conversion unit An image pickup apparatus that controls the iris in accordance with a photometric value generated by.   The imaging apparatus according to claim 1, wherein the coefficient generated by the coefficient generation unit increases when the iris aperture diameter is small, and decreases when the iris aperture diameter is large. .

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