JP2005303818A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus, capable of detecting not only a white defective pixel but also a black defective pixel, using a simple configuration and accurately correcting the deterioration of image quality caused by these defective pixels. <P>SOLUTION: A digital camera 1 includes a bent lens barrel 20 for forming the image of an object on an imaging device 25 for photoelectrically transducing the object image into an electrical signal, a digital signal processing section 4 for applying predetermined image processing on the electrical signal read from the imaging device 25, and a defective pixel information recording section 44 for recording defective pixel information of the imaging device 25, and comprises a defective pixel correction section 42 for performing predetermined defective pixel correction. A lens barrier 2, comprising light diffusion and light transmission properties, is provided in the aperture part of the bent lens barrel 20, and external light can be converted into predetermined diffusion light (detection light) and guided to the imaging device 25, so that black defective pixels can be detected, while closing the lens barrier 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image pickup apparatus using an image pickup element that photoelectrically converts a subject image into an electric signal and capable of detecting a defective pixel of the image pickup element and correcting the defect, and in particular, simplifying a black defective pixel. The present invention relates to an imaging apparatus that can be detected with a simple configuration.

  In a solid-state imaging device such as a CCD (charge coupled device) imaging device, a defective pixel that does not perform a predetermined photoelectric conversion operation may occur. Such defective pixels include black defective pixels and white defective pixels. A black defective pixel is also called a black defect, and is an image defect that appears as a black spot when a bright subject is photographed, for example. The white defect pixel is also called a white defect, and is an image defect in which, for example, a defective portion appears as a white spot during night photographing.

If even one such defective pixel exists, the defect is noticeable and the quality of the captured image is significantly reduced. On the other hand, it is practically difficult to produce an image sensor having no defective pixels and to maintain a state in which there are no defective pixels for a long time. Therefore, for example, as disclosed in Patent Document 1 or Patent Document 2, defective pixels are detected from a captured image in a timely manner, and the addresses of the detected defective pixels are stored in a defective pixel information recording unit or the like, and image data is stored. Conventionally, there has been a technique in which an imaging apparatus is provided with defective pixel correction means for performing interpolation processing based on output data of sound pixels existing in the vicinity of output data of pixels corresponding to stored addresses at the time of recording, etc. It is taken.
JP 2002-354340 A Japanese Patent Laid-Open No. 2003-116033

  The white defect pixel is a defect that appears as a white spot in a captured image with weak subject light. Therefore, when detecting the defect, the incident light to the image sensor may be blocked. Therefore, as shown in Patent Document 1, for example, white defective pixels can be detected relatively easily by using a light shielding plate such as a shutter to place the imaging system in a light shielding state.

  However, a black defect pixel is a defect that appears as a black dot when the subject light is a relatively strong photographed image. Therefore, when the defect is detected, a state in which constant incident light is given to the image sensor is created. There is a need to. It is relatively difficult to create such a black defective pixel detection environment by utilizing a mechanism included in a general imaging device. For this reason, in Patent Document 2, a dedicated light source for detecting black defective pixels is provided on a charging camera stand, and measurement light is transmitted from the dedicated light source to the imaging device in a timely manner in a state where the camera is mounted on the camera stand. Is used.

  However, according to the configuration of Patent Document 2, it is necessary to prepare a dedicated light source for detecting black defective pixels, and black defective pixels cannot be detected unless the camera is mounted on a camera stand. There is a bug. Therefore, an object of the present invention is to provide an imaging apparatus that can detect not only white defective pixels but also black defective pixels with a simple configuration and can accurately correct deterioration in image quality due to these defective pixels.

  An image pickup apparatus according to a first aspect of the present invention includes an image pickup unit including an optical lens and an image pickup device that photoelectrically converts a subject image into an electric signal, and image processing that performs predetermined image processing on the electric signal read from the image pickup device. In an imaging apparatus having a defective pixel information recording unit for recording defective pixel information of an image sensor and a defective pixel correction unit for performing predetermined defective pixel correction, external light is converted into predetermined detection light. Light guide means for enabling light guide to the image sensor is provided, and defective pixel information detected when inspection light is incident on the image sensor via the light guide means is recorded in the defective pixel information recording section. It is made possible.

  According to such a configuration, external light (light in the environment in which the imaging device is placed) is taken in by the light guide unit, converted into predetermined inspection light, and guided to the imaging device. When the light is incident on the image sensor, the defective pixel is detected and the defective pixel information is recorded in the defective pixel information recording unit. Since the defective pixel detected at this time is a defective pixel when a predetermined inspection light is irradiated on the image sensor, it becomes defective pixel information about the black defective pixel. Therefore, it is possible to detect black defective pixels based on the inspection light guided by the light guide means without providing a dedicated light source for detecting black defective pixels.

  In the above configuration, the light guiding means takes light from the outside into the imaging apparatus in an environment where the imaging apparatus is placed, converts the light into predetermined inspection light, and then guides it to the imaging device included in the imaging means If it is, there is no restriction | limiting in particular about the specific aspect. For example, a light guide window is provided in the main body of the imaging apparatus, a spectral path from the light guide window to the imaging element is provided, and a means for converting the inspection light into the spectral path is provided, or the imaging means is provided. It is possible to adopt a configuration in which the subject image incident optical path is also used as the optical path in the light guide unit, and the conversion unit for inspection light is installed in the optical path.

  In the imaging apparatus, it is desirable that the inspection light guided by the light guiding means is diffused light that is uniformly irradiated to the entire area of the imaging element. By converting the light taken from the outside into such diffused light and irradiating the image sensor, the detection accuracy of the black defective pixel can be improved.

  In the configuration according to claim 2, it is desirable that the light guide means includes a light-transmitting and light-diffusing conversion member disposed so as to be able to appear and retract with respect to the optical path of the imaging means. 3). With such a configuration, it is possible to irradiate the image pickup element after converting the light taken in from the outside by the light guide means into predetermined diffused light simply by positioning the conversion member in the optical path.

  Further, in the configuration according to claim 3, a lens barrier that protects the optical lens provided in the image pickup means is provided, and the lens barrier includes at least a part having a light transmitting property and a light diffusing property. It is desirable that the barrier also serves as a conversion member in the light guide means. According to this configuration, it is possible to construct the light guide unit according to the present invention by utilizing the lens barrier which is a component that is generally included in a general imaging device.

  In the above configuration, it is desirable that the defective pixel detection by the inspection light via the light guiding unit is performed when the imaging apparatus is activated or stopped. According to this configuration, for example, in a normal operation of the imaging apparatus, a time period in which the lens barrier is closed, that is, a time period from when the imaging apparatus is activated until it reaches shooting standby, or when a start / stop operation is performed, the power is turned on. Even if the user does not perform any conscious operation during the time period before power off or when the power is turned off, the black defective pixel detection operation is automatically performed, and the defective pixel information is recorded as defective pixel information. Can be recorded on the part.

  An image pickup apparatus according to a sixth aspect of the present invention includes an image pickup unit including an optical lens and an image pickup device that photoelectrically converts a subject image into an electric signal, and image processing that performs predetermined image processing on the electric signal read from the image pickup device. An image pickup apparatus including a defective pixel detection unit that detects a defective pixel of the image pickup device and a defective pixel information recording unit that records detected defective pixel information, and that performs predetermined defective pixel correction The imaging means includes a shutter capable of blocking the optical path of the imaging means, and a light transmissive property and a light diffusing property that are disposed so as to be able to project and retract with respect to the optical path of the imaging means and protect the optical lens provided in the imaging means. And the defective pixel detection unit has a defective pixel in a state where the shutter is open and the lens barrier is located in the optical path. Performs detection operation, the defective pixel information detected at this time is characterized in that it is capable recorded in the defective pixel information recording unit. According to this configuration, since the defective pixel detection operation is performed in the presence of light (inspection light) that passes through a lens barrier having light transmittance and light diffusibility, the black defective pixel can be configured with a simple configuration. Can be detected.

  In the above configuration, the defective pixel detection unit includes a white pixel defect detection mode for detecting a defective pixel of a white pixel when the shutter is closed, and the lens barrier is positioned in the optical path when the shutter is open. A configuration in which defective pixel detection operation is performed in a black pixel defect detection mode for detecting a defective pixel of a black pixel in a state, and defective pixel information detected in these detection operations can be recorded in the defective pixel information recording unit (Claim 7). According to this configuration, detection of the black defective pixel and the white defective pixel can be easily performed by appropriately controlling the opening / closing of the shutter and the appearance of the lens barrier in the subject image optical path.

  According to the imaging apparatus of the first aspect, the configuration in which external light is converted into predetermined detection light by the light guide means and guided to the imaging element is employed. Detection can be performed. In addition, unlike the imaging device disclosed in Patent Document 2, it is not necessary to provide a dedicated light source for detecting black defective pixels separately, so that it is possible to detect black defective pixels with a simple device configuration.

  According to the imaging device of the second aspect, since the imaging device is configured to convert the diffused light that is uniformly irradiated to the entire area of the imaging device and irradiate the imaging device, the detection accuracy of the black defective pixel is improved. The defective pixel correction means can perform more appropriate defective pixel correction, and the quality of the captured image can be further improved.

  According to the imaging device of the third aspect, the light taken in from the outside by the light guide means is converted into the predetermined diffused light only by positioning the light transmissive and light diffusing conversion member in the optical path, and then imaged. Since the element can be irradiated, there is an effect that it is possible to provide an imaging device capable of detecting black defective pixels with a simple configuration.

  According to the imaging device according to the fourth aspect of the present invention, since the lens barrier which is a constituent element that is generally included in a general imaging device is used, an additional configuration is required when constructing the light guide unit according to the present invention. Is not required. Therefore, it is possible to provide an imaging apparatus capable of detecting black defective pixels without complicating the configuration of the imaging apparatus.

  According to the imaging device of the fifth aspect, the detection operation of the black defective pixel is automatically performed, and the defective pixel information can be recorded in the defective pixel information recording unit. Even if it does not do, the data update of defective pixel information will be automatically performed, and the convenience of the user can be improved.

  According to the imaging device of the sixth aspect, since the defective pixel detection operation is performed in the presence of light (inspection light) that passes through a lens barrier having light transmittance and light diffusibility, conventionally, Detection of black defective pixels, which has been difficult, can be performed with a simple configuration.

  According to the imaging device of the seventh aspect, the black defective pixel and the white defective pixel can be easily detected by appropriately controlling the opening / closing of the shutter and the appearance of the lens barrier in the object image optical path. it can. Therefore, there is an effect that an imaging apparatus having a black defective pixel detection function and a white defective pixel detection function can be achieved by utilizing components that are generally included in a general imaging apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are views showing the appearance of a small digital camera 1 to which an imaging apparatus according to the present invention is preferably applied. FIG. 1A is a top view, FIG. 1B is a front view, and FIG. Each show a rear view. The camera (imaging device) 1 includes a power button 101 and a release button 102 on the top surface of the camera body 10, a flash light emitting unit 103 and a photographing lens window 104 on the front side, and various types on the back side. The display unit 106 including an operation button 105, a liquid crystal monitor (LCD), and the like are arranged. In addition to the various main body devices, a bending lens barrel 20 and a vertically movable lens barrier 2 are disposed inside the main body 10.

  The power button 101 is a push switch for turning on (starting) and turning off (starting stop) the power of the camera 1, and the camera power is turned on and off sequentially by the pressing operation. The release button 102 is a push switch for performing a transition from the through image display mode to the shooting mode and a shutter start operation in the shooting mode. The flash light emitting unit 103 illuminates the subject when the subject image is dark with the release button 102 pressed (half-pressed) (shooting mode). The photographic lens window 104 is an opening for taking an optical image of a subject into the bending lens barrel 20 disposed inside the main body 10. The operation button 105 is a push switch group such as a zoom switch, a menu selection switch, and a selection determination switch. The display unit 106 reproduces and displays a recorded image recorded on a built-in recording medium, and displays a through image (live view image) of a subject that has been video-captured during shooting standby.

  The bendable lens barrel 20 constitutes a photographic lens system that takes a subject image through the photographic lens window 104 and guides it to the image sensor 25 disposed inside the main body 10. The bent lens barrel 20 is a lens barrel that does not vary in length even during zooming or focusing drive, that is, does not protrude outward from the main body 10.

  FIG. 2 is a cross-sectional view of the bent lens barrel 20. The bent lens barrel 20 has a cylindrical shape that is built in the vertical direction inside the camera body 10, and is externally a cylindrical portion 200 that stores a lens group, and a photographic lens of the camera body 10. It is arranged in alignment with the window 104 and includes a bent portion 202 having an opening 201 through which a subject image enters the inside of the lens barrel. The bent portion 202 is provided with a photographic lens (objective lens) 21 fixed to the opening 201 and a mirror 22 that is disposed on the inclined side of the bent portion 202 and changes the direction of the subject optical axis from horizontal to downward. It has been. Although the detailed structure is omitted in the cylindrical portion 201, a lens group 23 constituting a photographing optical system including a zoom lens block and a fixed lens block is arranged in series along the optical axis. . A shutter 24 is disposed at an intermediate portion of the lens group 23, and the optical path of the photographing optical system is shielded or transmitted by opening / closing the shutter 24.

  An imaging element 25 such as a CCD type imaging element or a CMOS type imaging element is disposed at the deepest part (bottom part) of the bending type lens barrel 20. The imaging element 25 has a configuration in which photoelectric conversion sensors are arranged in a grid pattern, and each part of the sensor (pixel) converts it into an electrical signal according to the irradiated optical image and outputs it. The image pickup device 25 can be irradiated (exposed) with an optical image formed by a photographing optical system including the lens group 23. The exposure start and end, and the control of the exposure time are as described above. This is performed by controlling the opening / closing operation of the shutter 24.

  That is, when the shutter 24 is in an “open” state for a predetermined exposure time, charges corresponding to the amount of irradiation light are accumulated in each sensor constituting the pixel in accordance with the optical image formed on the image sensor 25, The pixel sensor outputs an electrical signal according to the amount of light, and this output signal is sent to a digital signal processing unit described later to form a predetermined image. However, abnormal pixels that output electrical signals that do not depend on the amount of irradiation light may occur in the pixel sensor. Typical examples are the above-described white defect pixel and black defect pixel. The output of such defective pixels is complemented so as not to appear on the image by the defective pixel correction processing. This point will be described in detail later.

  The lens barrier 2 is a vertically movable protection member (movable in the direction of arrow a in FIG. 2) that opens or closes the photographing lens window 104, that is, the opening 201 of the bent lens barrel 20. The lens barrier 2 moves downward when the power ON operation is performed by the power button 101 so that the photographing lens window 104 can be opened and can be photographed. When the power OFF operation is performed, the lens barrier 2 The window 104 is “closed” to protect the photographing lens 21 from external force or the like. An appropriate mechanism may be adopted for the opening / closing mechanism of the lens barrier 2, and other than the above-described vertically movable type, for example, a horizontally movable type, a door opening type, or the like may be used.

  The lens barrier 2 as described above is provided for protecting a photographing lens even in a general digital camera or the like, but is usually constituted by a light-shielding member. However, in this embodiment, the lens barrier 2 has light transmittance and light diffusibility because the configuration in which the optical path of the light guide unit according to the present invention and the optical path of the imaging lens system are combined is adopted. A member is used.

That is, a requirement of the light guide means in the present invention,
(1) Convert external light into predetermined detection light,
(2) The light can be guided to the image sensor 25.
With respect to the above point, the role of the conversion member to the inspection light of (1) is secured by providing the lens barrier 2 with light transmittance and light diffusibility, and the image sensor 25 of (2) Regarding the light guide path of the inspection light, an aspect using the incident optical path of the subject image provided in the bent lens barrel 20, that is, the light transmittance in which the light guide means is arranged so as to be able to appear and retract with respect to the optical path of the imaging means, and This embodiment exemplifies an aspect including a conversion member (in this case, the lens barrier 2) having light diffusibility.

  Here, as the conversion member having light transmittance and light diffusibility, a resin molded product obtained by blending a predetermined amount of minute light scattering particles with a light transmissive base resin, a minute amount on the surface of the member having light transmissive property. It is possible to use a molded product that has been subjected to rough processing (rough surface processing), or a member in which a light diffusion film is attached to a translucent substrate. In addition, it is also possible to use a plate material (semi-permeable milky white plate) such as polyethylene which does not contain a colorant.

  Note that the lens barrier 2 is not necessarily composed entirely of a light transmissive and light diffusing member, but at least part of the lens barrier 2 includes a light transmissive and light diffusing portion. It suffices that the external light that has passed through the light diffusing region reaches the image sensor 25 disposed at the bottom of the bending lens barrel 20.

  By arranging such a lens barrier 2 in the opening 201 of the bent lens barrel 20, external light passes through the lens barrier 2 even when the lens barrier 2 blocks the photographing lens window 104. By doing so, it is converted into diffused light (inspection light) and taken into the bent lens barrel 20. If the shutter 24 is in the “open” state, the image sensor 25 is irradiated with the inspection light. Moreover, since the inspection light to be irradiated is diffuse light, the entire area of each pixel sensor included in the image sensor 25 is irradiated with a substantially uniform light amount. Therefore, in detecting black defective pixels, a very preferable detection environment can be created.

  FIG. 3 is a block diagram of an imaging process performed by the digital camera 1 according to the present embodiment. In the figure, the same parts as those shown in FIGS. 1 and 2 are denoted by the same reference numerals. The digital camera 1 has an analog signal processing unit 31, a TG (timing generator) unit 32, a camera control unit 33, a shutter driving unit 34, and a lens barrier driving unit in addition to the configuration described above with reference to FIGS. 35, a digital signal processing unit 4, a defective pixel address recording unit 44, a memory card 107, an image memory unit 5, and the like.

  The analog signal processing unit 31 performs predetermined signal processing on the image signal (analog signal group received by each pixel of the CCD area sensor) output from the image sensor 25, and then converts it into a digital signal and outputs it. It is. Although not shown, the analog signal processing unit 31 includes a CDS circuit (correlated double sampling circuit), an AGC circuit, an A / D conversion circuit, and the like. The CDS circuit reduces reset noise included in the analog image signal, the AGC circuit corrects the level of the analog image signal, and the A / D conversion circuit converts the analog image signal into, for example, a 10-bit digital image signal (image Data). The analog signal processing unit 31 is called an AFE (analog front end) and is generally configured by a single IC.

  The TG (timing generator) unit 32 controls the photographing operation of the image sensor 25 (charge accumulation based on exposure, reading of accumulated charge, etc.). The timing generator unit 32 generates a predetermined timing pulse (vertical transfer pulse, horizontal transfer pulse, charge sweep pulse, etc.) based on the imaging control signal from the camera control unit 33, and outputs the generated timing pulse to the image sensor 25 for displaying a through image. In the mode, for example, a frame image is captured every 1/30 (seconds), and is sequentially output to the analog signal processing unit 31. Further, during exposure in the shooting mode, charges are accumulated in conjunction with the exposure operation of the image sensor 25 (that is, the subject light image is photoelectrically converted into an image signal), and the accumulated charges are output to the analog signal processing unit 31. Let

  The camera control unit 33 performs centralized control of the shooting operation of the digital camera 1. The camera control unit 33 transmits a predetermined shooting control signal to the timing generator unit 32 as described above, and controls the shutter driving unit 34 and the lens barrier driving unit 35. The shutter driving unit 34 performs an opening / closing operation of the shutter 24 in accordance with an instruction from the camera control unit 33. Similarly, the lens barrier driving unit 35 moves up and down the lens barrier 2 (that is, the opening / closing operation of the photographing lens window 104 according to an instruction from the camera control unit 33. In other words, the conversion member for converting the external light into the inspection light, (Moving in and out of the subject image photographing optical path).

  Although not shown in the drawing, the camera control unit 33 adjusts the focal length disposed in the aperture driver that adjusts the optical aperture of the photographing optical system based on a predetermined aperture value or the bending lens barrel 20. The zoom lens and the focus / lens motor driver for driving the focus lens are controlled to perform shooting, and the analog signal processing unit 31, the digital signal processing unit 4, and the LCD display unit 106 are controlled to perform shooting. After performing predetermined image processing on the image, the captured image is recorded on the memory card 107 or displayed on the LCD display unit 107. In other words, each frame image during standby for shooting (through image display mode) is subjected to predetermined image processing in the analog signal processing unit 31 and a digital signal processing unit 4 described later, and then is displayed on the LCD display unit 106 as a live image (live image). View image). In the photographing mode, the photographed image is subjected to predetermined image processing by the analog signal processing unit 31 and the digital signal processing unit 4 and then recorded on the memory card 107 as a recorded image.

  The aperture value and the exposure time are set by extracting an image signal included in a predetermined photometry area set in advance on the screen from an image signal captured by the image sensor 25 during shooting standby (exposure described later). The value is extracted by the level detection unit 45), and an exposure control value at the time of shooting is calculated using the image signal, and the calculation result and a preset program diagram are used.

  In addition to the basic imaging operation as described above, the camera control unit 33 controls the shutter driving unit 34 and the lens barrier driving unit 35 in the case of performing the detection operation of white defective pixels and black defective pixels (defective pixel detection mode). A signal is given and the lens barrier 2 and the shutter 24 are appropriately controlled. That is, when white defect pixel detection is performed (white pixel defect detection mode), the shutter drive unit 34 is controlled so that the shutter 24 is “closed”. When black defective pixel detection is performed (black pixel defect detection mode), the shutter 24 is in the “open” state and the lens barrier 2 is positioned at the opening 201 of the bent lens barrel 20, that is, the photographing lens. The shutter drive unit 34 and the lens barrier drive unit 35 are controlled so as to cover the window 104. Then, control is performed so that defective pixel information detected in the white pixel defect detection mode and black pixel defect detection mode is recorded in the defective pixel information recording unit 44.

  The digital signal processing unit 4 processes the digital image data output from the analog signal processing unit 31, and controls reproduction display of the digital image after data processing on the LCD display unit 106 and recording on the memory card 107. It is. The digital signal processing unit 4 includes an image processing unit 41, a defective pixel correcting unit 42, a defective pixel detecting unit 43, an exposure level detecting unit 45, an LCD display I / F unit 46, and a memory card I / F unit 47. Yes. The defective pixel correction unit 400 and the defective pixel detection unit 43, and the defective pixel address recording unit 44 constitute a defective pixel correction unit 400 according to the present invention.

  The image processing unit 41 performs signal processing such as resolution conversion, white balance adjustment, gamma correction, and image compression / decompression to create an image file and receives a control signal from the camera control unit 33 to display a through image display. In the mode, the digital image after signal processing is displayed on the LCD display unit 106 via the LCD display I / F unit 46. In the shooting mode, the digital image after signal processing is displayed via the memory card I / F unit 47. 107 is recorded. The image data captured by the image processing unit 41 is temporarily written in the image memory unit 5 in synchronization with the reading of the image sensor 25. Thereafter, the image data written in the image memory unit 5 is accessed to obtain the image data. Various processes are performed inside the processing unit 41.

  The image processing unit 41 is provided with a resolution conversion circuit 411, a white balance (WB) control circuit 412, a gamma correction circuit 413, and the like for performing the above-described signal processing.

  The resolution conversion circuit 411 converts the resolution into the set number of recorded image pixels. In other words, the resolution of the image data after pixel interpolation is converted to a predetermined number of recorded image pixels by performing compression or thinning in the horizontal or vertical direction. Further, when generating an image for display on the LCD display unit 106, a low-resolution image for display is created by thinning out horizontal pixels by the resolution conversion circuit 411.

  The white balance control circuit 412 adjusts the white balance (WB) of the pixel-interpolated digital image. The white balance control circuit 412 reads out image data of R and B color components from the image memory unit 5 and performs level correction based on the WB adjustment data set by the camera control unit 33, respectively. That is, the white balance control circuit 412 specifies a portion that is originally estimated to be white from the luminance, saturation data, and the like in the photographic subject, and calculates an average of R, G, and B color components of that portion, and G / The R ratio and the G / B ratio are obtained, and the levels are corrected as R and B correction gains. The corrected image data is stored in the image memory unit 5 again.

  The gamma correction circuit 413 corrects the gradation characteristics of the WB-adjusted image data to the gradation characteristics of the LCD display unit 106 or an externally output monitor television. The gamma correction circuit 413 performs non-linear conversion and offset adjustment of the level of the image data read from the image memory unit 5 using a predetermined gamma characteristic for each color component. The converted and adjusted image data is again stored in the image memory unit 5.

  A digital signal including an output signal from not only a healthy pixel but also a defective pixel is input to the digital signal processing unit 4 from the analog signal processing unit 31. If such a digital signal is processed as it is, an image including white defects and black defects due to defective pixels is reproduced and recorded. Therefore, a defect for correcting such defective pixels is provided before the image processing unit 41. A pixel correction unit 42 is provided.

  That is, the defective pixel correction unit 42 interpolates data of pixel positions where the frame image is insufficient for each of the R, G, and B color components. For example, when a single-plate CCD image sensor in which pixels of R, G, and B color components are arranged in a checkered pattern is used as the image sensor 25, the frame image of each color component is a discretely arranged pixel. Although it is composed of a plurality of position data (image data), the defective pixel correction unit 42 interpolates (corrects) pixel data at non-existing pixel positions using a plurality of existing pixel data.

  Specifically, the image data of the R, G, and B color components input from the analog signal processing unit 31 and temporarily stored in the image memory unit 5 are read out to the defective pixel correction unit 42 and the pixel data A defective pixel correction process is performed. The defective pixel correction unit 42 masks the image data constituting the frame image with a predetermined filter pattern for the G color component frame image having pixels up to a high band, and then uses a median (intermediate value) filter. Of the pixel data actually existing around the pixel position to be corrected, an average value of the pixel data from which the maximum value and the minimum value are removed is calculated, and the average value is corrected as pixel data at the pixel position. For the R and B color components, after the image data constituting the frame image is masked with a predetermined filter pattern, the average value of the pixel data actually existing around the pixel position to be corrected is calculated, and the average value is calculated. Is corrected as pixel data at the pixel position. Then, the frame image data of each color component after the pixel correction by the defective pixel correction unit 42 is stored in the image memory unit 5 again.

  The defective pixel detection unit 43 detects a white defective pixel in the white pixel defect detection mode when the camera control unit 33 performs an operation in a defective pixel detection mode in which white defective pixels and black defective pixels are detected. In the black pixel defect detection mode, black defective pixels are detected, addresses of defective pixels are extracted and recorded in the defective pixel address recording unit 44, respectively.

  Here, the white defect pixel and the black defect pixel will be described with reference to FIG. First, FIG. 4A is a diagram showing the effective imaging area 250 of the imaging device 25 in a plan view. In the effective imaging area 250, there are tens of thousands to millions of pixel sensors regularly arranged. FIG. 4A shows a pixel group that exists one-dimensionally between AA ′ lines in the effective imaging area 250 in order to simplify the description. That is, the black dots between the lines AA ′ indicate each pixel sensor.

  As shown in FIG. 4B, the white defective pixel is a pixel that generates an output signal having a higher level than other pixels even though the effective imaging area 250 is in a light-shielded state. . On the other hand, as shown in FIG. 4C, the black defective pixel generates only an output signal at a lower level than the other pixels even though the effective imaging area 250 is in a uniform light irradiation state. Such a pixel.

  As described above, in order to detect white defective pixels, it is desirable that the effective imaging area 250 of the image sensor 25 be in a dark state, particularly in a completely light-shielded state (white pixel defect detection mode). On the other hand, in order to detect black defective pixels, it is desirable that the effective imaging area 250 of the image sensor 25 is irradiated with light, particularly a uniform light irradiation state (black pixel defect detection mode). A desirable detection environment in the white pixel defect detection mode can be easily created by controlling the shutter drive unit 34 so that the shutter 24 is “closed”. In this respect, the same applies to other than the digital camera 1 according to the present invention.

  However, it is difficult to create a desirable detection environment in the black pixel defect detection mode with an ordinary digital camera or the like. On the other hand, according to the digital camera 1 of the present invention, a desirable detection environment in the black pixel defect detection mode can be easily created, and this is a feature of the present invention. That is, in the black pixel defect detection mode, the shutter 24 is in an “open” state, and the lens barrier 2 having light transmittance and light diffusibility covers the photographing lens window 104, so that the digital Light in the environment where the camera 1 is placed (external light) is converted into diffused light (inspection light), and then the entire effective imaging area 250 of the image sensor 25 can be irradiated with light substantially uniformly. By adopting such a configuration, black defective pixels are accurately detected by the defective pixel detection unit 43.

  Returning to FIG. 3, the defective pixel address recording unit (defective pixel information recording unit) 44 includes a memory such as a ROM or a RAM. The defective pixel address recording unit 44 includes white pixels detected by the defective pixel detection unit 43. Address information of defective pixels and black defective pixels is recorded. The defective pixel information recorded in the defective pixel address recording unit 44 is read by the defective pixel correction unit 42 and used as reference information when the defective pixel correction unit 42 corrects defective pixels.

  The exposure level detection unit 45 extracts an image signal included in a predetermined photometry area preset in the screen from the image signal captured by the image sensor 25 via the image processing unit 41, and uses the image signal. Then, the image data exposure level (brightness level) at the time of shooting is detected and output to the camera control unit 33.

  The LCD display I / F unit 46 converts the LCD display image data generated by the image processing unit 41 into, for example, an NTSC or PAL image signal and outputs the image signal to the LCD display unit 106. The memory card I / F unit 47 outputs the memory card recording image data generated by the image processing unit 41 so as to be recorded on the memory card 107.

  The image memory unit 5 includes a memory such as a ROM or a RAM, and temporarily stores the image data in order to perform predetermined digital image processing on the image data. The image memory unit 5 has a capacity capable of storing, for example, three images, and the captured image is stored in a state of being separated into R, G, and B color components. The memory card 107 is a memory for recording and storing the above-described image data, and is detachable from the digital camera 1 so that image data can be exchanged with an external recording medium. To do.

  The operation of the digital camera 1 according to the present invention configured as described above will be described based on the flowchart shown in FIG. 5 and the block diagram of FIG. The digital camera 1 according to the present embodiment includes a through image display mode M1 for displaying a live view image that is shot during shooting standby, a shooting mode M2 for shooting and recording a subject image, a white defect pixel, and a black defect. And a defective pixel detection mode M3 for detecting pixels.

  In an initial state, the power of the digital camera 1 is turned off and the lens barrier 2 covers the photographing lens window 104 (the lens barrier 2 is located in the upward direction, that is, in the opening 201 of the bent lens barrel 2 and photographed. The lens 21 is protected). In this state, first, it is detected whether or not the power button 101 is pressed to shift to the power ON state (step S1). When the power button 101 is not pressed (the power is off), the detection loop is continued.

  On the other hand, when the power is turned on, an operation control signal for “lens barrier opening” is sent from the camera control unit 33 to the lens barrier driving unit 35, and the lens barrier driving unit 35 generates a driving signal to generate a lens. The barrier 2 is driven, the lens barrier 2 at the position of the opening 201 is moved downward, and the photographing lens window 104 is opened (step S2). Further, an operation control signal is sent from the camera control unit 33 to the shutter drive unit 34 so that the shutter 24 inside the bending lens barrel 20 is also opened, and the shutter drive unit 34 generates a drive signal to control the shutter 24. The “open” state is set (step S3). By this operation, the light image of the subject reaches the image sensor 25 through the photographing lens window 104, and shifts to the through image display mode M1 (shooting standby state).

  In the through image display mode M1, subject image data (frame image data) photographed by the image sensor 25 is digitized by the analog signal processing unit 31, and then predetermined image processing is performed by the digital signal processing unit 4. After that, it is displayed as a through image on the LCD display unit 106 (step S4).

  In the state of step S4, it is detected whether or not the release button 102 is pressed to be in the ON state (step S5). If the release button 102 is pressed, the process proceeds to the shooting mode M2. In the shooting mode M2, a predetermined shooting control signal is sent from the camera control unit 33 to the timing generator unit 32, and an imaging operation is performed with the exposure amount and the like being set to a predetermined condition. Then, the signal is digitized by the analog signal processing unit 31 and subsequently subjected to predetermined image processing by the digital signal processing unit 4 and then recorded in the memory card 107 (step S7).

  On the other hand, when the release button 102 is not pressed, it is detected whether the power button 101 is pressed again and the power is turned off (step S6). Also, when the photographing operation in step S7 is completed, the photographing mode M2 returns to the through image display mode M1, and the detection operation in step S6 is performed similarly. If the power button 101 is not pressed and the power ON state is maintained, the process returns to step S4 and the same operation is repeated, and a through image is displayed on the LCD display unit 106.

  On the other hand, when the power button 101 is pressed again and preparation for the power OFF state is started, the mode is shifted to the defective pixel detection mode M3. When the mode is shifted to the defective pixel detection mode M3, an operation control signal “lens barrier closed” is sent from the camera control unit 33 to the lens barrier driving unit 35, and the lens barrier driving unit 35 generates a driving signal to generate a lens barrier. 2 is driven to move the lens barrier 2 positioned below the opening 201 upward. As a result, the photographing lens window 104 is covered with the lens barrier 2 (step S8). However, since the lens barrier 2 is light transmissive and light diffusive, the lens barrier 2 is not in a light shielding state, and external light from the photographing lens window 104 is converted into diffused light (inspection light) by the lens barrier 2. In addition, the light enters the bent lens barrel 20. At this time, the shutter 24 is in an “open” state, and the image sensor 25 is in a state in which diffused light incident through the lens barrier 2 can be detected.

  Subsequently, based on the data relating to the exposure level emitted from the exposure level detection unit 45, the camera control unit 33 determines whether or not the exposure level is suitable for detecting a black defective pixel (step S9). That is, when detecting a black defective pixel, as shown in FIG. 4C, each pixel sensor in the effective image pickup area 250 of the image pickup device 25 has reached a corresponding exposure state (a black defective pixel sensor and a healthy one). It is important that the photoelectric conversion output difference with the pixel sensor is distinguishable), but it is determined based on the output data of the exposure level detection unit 45 whether or not this state has been reached. .

  If it is determined that the appropriate exposure level has been reached (Yes in step S9), the defective pixel detection unit 43 performs a black defective pixel detection operation (step S10; black pixel defect detection mode). That is, as shown in FIG. 4C, it is confirmed whether there is a pixel sensor at a significantly lower output level than the output of other pixel sensors, and such a low output level pixel exists. In this case, the low output level pixel is detected as a “black defective pixel”. Then, the defective pixel detection unit 43 extracts the address of the “black defective pixel” and causes the defective pixel address recording unit 44 to record this address as defective pixel information. The defective pixel information regarding the black defect recorded in the defective pixel address recording unit 44 in this way is used when the defective pixel correction unit 42 corrects the defective pixel.

  When the detection operation of the black defective pixel in step S10 is completed, an operation control signal is sent from the camera control unit 33 to the shutter driving unit 34 so that the shutter 24 inside the bending lens barrel 20 is “closed”. As a result, the shutter drive unit 34 generates a drive signal to put the shutter 24 in the “closed” state (step S11). If it is determined in step S9 that the appropriate exposure level has not been reached (No in step S9), for example, the pressing operation of the power button 101 in step S6 is performed in a dark place (such as at night), and diffused light (inspection) Even when a state in which light is not incident through the lens barrier 2 continues for a predetermined time, it is assumed that the detection environment for detecting a black defective pixel has not been prepared, and the execution of the detection operation is skipped. Closed ".

  When the shutter 24 is “closed” in step S <b> 11, the image sensor 25 is in a light shielding state. That is, the white defect pixel detection environment shown in FIG. 4B is created. Therefore, the defective pixel detection unit 43 performs a white defective pixel detection operation (step S12; white pixel defect detection mode). That is, as shown in FIG. 4B, it is confirmed whether there is a pixel sensor at a significantly higher output level than the output of other pixel sensors, and such a high output level pixel exists. In this case, the high output level pixel is detected as a “white defect pixel”. Then, the defective pixel detection unit 43 extracts the address of the “white defective pixel” and causes the defective pixel address recording unit 44 to record this address as defective pixel information. The defective pixel information regarding the white defect recorded in the defective pixel address recording unit 44 in this way is used when the defective pixel correction unit 42 corrects the defective pixel.

  When the defective pixel detection mode M3 as described above is completed, the power source of the digital camera 1 is completely shut off, and the state is returned to the initial state in which the power source is OFF and the lens barrier 2 covers the photographing lens window 104. Become.

  In the flowchart of FIG. 5, the defective pixel detection mode M <b> 3 is when the power button 101 is pressed when the digital camera 1 is stopped, that is, when the power is on, and the photographing lens window 104 is covered by the lens barrier 2 and the power is turned off. However, the present invention is not limited to this and can be executed at an appropriate timing. However, as in this embodiment, when the digital camera 1 is stopped or started, that is, until the power button 101 is pressed and the lens barrier 2 is opened in the power OFF state (steps S1 and S2). In the meantime, it is desirable to execute the black pixel defect detection mode (steps S9 and S10) or to execute it in an arbitrary time zone when the power is turned off. According to this configuration, during the normal operation of the digital camera 1, the black defective pixel detection operation is automatically performed during the time period when the lens barrier 2 is closed, and the defective pixel information is stored in the defective pixel address recording unit 44. Thus, there is an advantage that the defective pixel information can be automatically updated sequentially without requiring any conscious operation by the user.

  As mentioned above, although embodiment of this invention was described, this invention can be implemented by changing said structure variously. For example, in the above-described embodiment, the digital camera 1 (imaging device) using the bent lens barrel 20 whose length does not change during zooming or focusing drive has been described. However, this can be replaced with a retractable lens barrel. May be.

  In such a retractable lens barrel, a lens barrier 6 as shown in FIG. 6 is generally used. That is, the lens barrier 6 includes a barrier member 60 including a first barrier piece 61 and a second barrier piece 62 that cover the photographing lens opening 600, and each barrier piece 61, 62 is a rotating shaft 611, 612. The drive unit 612 and 622 generally includes a configuration in which the photographing lens opening 600 is rotatably arranged so as to be in an open state or a closed state. In the lens barrier 6 having such a configuration, the first barrier piece 61 and the second barrier piece 62 are made of a member having light transmission and light diffusibility, and the first barrier piece 61 and the second barrier piece 62 are formed. If the same operation is performed by replacing the opening / closing operation of the barrier piece 62 with the above-described vertical movement operation of the lens barrier 2, it is possible to provide an imaging device that can easily detect and correct black defective pixels.

  Further, regarding the light guide path of the inspection light by the light guide means, in the above embodiment, the aspect using the incident light path of the subject image provided in the bent lens barrel 20 is exemplified, but the light guide means in the present invention is the imaging device. If the light is taken into the imaging device from the outside in the environment where it is placed, converted into predetermined inspection light, and then led to the imaging device included in the imaging means, there are no particular restrictions on the specific mode. Absent. For example, a light guide window portion made of a conversion member having light transmittance and light diffusibility is provided in the main body of the image pickup device, and a spectral path from the light guide window portion to the image pickup device is provided, and diffused appropriately in the image pickup device. It is good also as a structure which can irradiate light.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the external appearance of the small digital camera with which the imaging device concerning this invention is applied suitably, Comprising: (a) is the top view, (b) is a front view, (c) shows the rear view, respectively. Yes. It is sectional drawing of the bending type lens barrel applied to the digital camera of FIG. It is an imaging process block diagram by the digital camera which concerns on this invention. It is explanatory drawing about a white defective pixel and a black defective pixel, (a) is explanatory drawing of an effective imaging area, (b) is explanatory drawing of a white defective pixel, (c) is explanatory drawing of a black defective pixel. It is a flowchart for demonstrating operation | movement of the digital camera concerning this invention. It is a top view which shows other embodiment of a lens barrier.

Explanation of symbols

1 Digital camera (imaging device)
DESCRIPTION OF SYMBOLS 10 Main body body 101 Power button 102 Release button 104 Shooting lens window 106 LCD display part 107 Memory card 2, 6 Lens barrier (Conversion member provided with light transmittance and light diffusibility)
20 Bent barrel (light guide)
21. Photography lens (optical lens)
24 Shutter 25 Image Sensor 31 Analog Signal Processing Unit 32 Timing Generator Unit 33 Camera Control Unit 34 Shutter Drive Unit 35 Lens Barrier Drive Unit 4 Digital Signal Processing Unit 41 Image Processing Unit (Image Processing Unit)
42 defective pixel correction unit 43 defective pixel detection unit 44 defective pixel address recording unit 45 exposure level detection unit 5 image memory unit

Claims (7)

An image pickup unit including an optical lens and an image pickup device that photoelectrically converts an object image into an electric signal, an image processing unit that performs predetermined image processing on the electric signal read from the image pickup device, and defective pixel information of the image pickup device are recorded. In an imaging apparatus having a defective pixel information recording unit and a defective pixel correction unit that performs predetermined defective pixel correction,
A light guide means for converting external light into predetermined detection light and enabling light to be guided to the image sensor;
An image pickup apparatus, wherein defective pixel information detected when inspection light is incident on an image pickup device via the light guiding means can be recorded in the defective pixel information recording unit.   The imaging apparatus according to claim 1, wherein the inspection light guided by the light guiding means is diffused light that is uniformly irradiated to the entire area of the imaging element.   3. The image pickup apparatus according to claim 2, wherein the light guide means includes a conversion member having a light transmission property and a light diffusion property arranged so as to be able to appear and retract with respect to the optical path of the image pickup means. A lens barrier that protects an optical lens included in the imaging unit is provided, and the lens barrier includes at least a part having light transmission and light diffusibility,
The imaging apparatus according to claim 3, wherein the lens barrier also serves as a conversion member in the light guide unit.   The imaging apparatus according to claim 1, wherein defective pixel detection by inspection light via the light guide is performed when the imaging apparatus is activated or stopped. An imaging means comprising an optical lens and an imaging device for photoelectrically converting a subject image into an electrical signal;
Image processing means for performing predetermined image processing on the electrical signal read from the image sensor;
In an imaging apparatus including a defective pixel detection unit that detects a defective pixel of an imaging element and a defective pixel information recording unit that records detected defective pixel information, and a defective pixel correction unit that performs predetermined defective pixel correction,
The imaging means includes a shutter capable of blocking the optical path of the imaging means, and a lens having a light transmitting property and a light diffusing property that are disposed so as to be able to project and retract with respect to the optical path of the imaging means and protect the optical lens provided in the imaging means. A barrier is attached,
The defective pixel detection unit performs a defective pixel detection operation in a state where the shutter is open and the lens barrier is positioned in an optical path,
An imaging apparatus, wherein defective pixel information detected at this time can be recorded in the defective pixel information recording unit. The defective pixel detector
A white pixel defect detection mode for detecting a defective pixel of a white pixel when the shutter is closed;
In a state where the shutter is open and the lens barrier is located in the optical path, a defective pixel detection operation is performed in a black pixel defect detection mode for detecting a defective pixel of a black pixel,
7. The imaging apparatus according to claim 6, wherein defective pixel information detected in these detection operations can be recorded in the defective pixel information recording unit.

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