JP2008005194A - Detecting device and detecting method for defective pixel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detecting device and a detecting method for defective pixel that can correct a different kind of defective pixel with high accuracy, according to a signal level. <P>SOLUTION: Disclosed are the detecting device 10 and detecting method for defective pixel that detect the defective pixel generated in an imaging area of a semiconductor element D, the detecting device, including a defective pixel detector 14 detecting the defective pixel; defective pixel address storage units 15 and 16 storing address information on a defective pixel detected from a photographed image in a first illuminance state, wherein the illuminance of light irradiating the imaging area is low and also storing address information detected from a photographed image, in a second illuminance state wherein the illuminance is higher than in the first illuminance state; an address comparator 17 for comparing pieces of address information on the defective pixels in the first illuminance state and second illuminance state stored in the defective pixel address storage units 15 and 16; and a correction address deciding unit 18 for determining execution correction address for the defective pixel, based on the comparison result of the pieces of address information on the defective pixel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a defective pixel detection apparatus and detection method, and more particularly, to a defective pixel detection apparatus and detection method capable of performing highly accurate correction on defective pixels of different types according to signal levels.

  In an image pickup apparatus including a semiconductor element such as a solid-state image pickup element, a defective pixel whose sensitivity decreases due to a local liquid crystal defect may occur in a pixel constituting an image pickup region of the semiconductor element. Among such defective pixels, those with generally low photoelectric sensitivity appear as black dots and are called black scratches.

FIG. 5 is a diagram showing the types of black scratches in the imaging region of the semiconductor element. In FIG. 5, reference numeral 1 denotes an imaging region of a semiconductor element, 2 denotes a horizontal transfer path, and 3 denotes an amplifier. 5 indicates a direction (vertical direction) perpendicular to the direction in which the horizontal transfer path is extended.
As shown in FIG. 5 (a), black scratches are isolated defective pixels that are not continuous in the vertical direction A (so-called point scratches) even when there is a defective pixel with reduced sensitivity when the signal level is high. p1 and p2. On the other hand, as shown in FIG. 5B, when the signal level is lowered, the defective pixels appearing at the high signal level are in a low transfer efficiency state, and defective pixels (so-called line lines) continuous in the vertical direction A are obtained. Scratch) may be p2. In general, the lower the signal level, the lower the transfer efficiency, so the number of defective pixels continuous in the vertical direction increases.

  Conventionally, a defective pixel of a semiconductor element has been detected before shipping an imaging device. The detected defective pixel is subjected to interpolation processing based on a signal of a normal pixel in the vicinity of the defective pixel. For example, as shown in Patent Document 1 below, black scratch detection is performed by determining whether or not the output signal level of each pixel of the solid-state imaging device is lower than a threshold value when imaging is performed with a constant light irradiation amount.

JP 2002-112118 A

  By the way, for defective pixels continuous in the vertical direction, it is necessary to perform pixel correction for one column in the vertical direction. However, as shown in FIG. 5, there are different types of defective pixels, that is, a defective pixel at an isolated point and a defective pixel continuous in the vertical direction, depending on the signal level. As a result, correction was performed for normal pixels, resulting in a decrease in yield.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a defective pixel detection apparatus and detection method capable of performing highly accurate correction on defective pixels of different types according to signal levels. There is to do.

  The object of the present invention is a detection device for detecting defective pixels generated in an imaging region of a semiconductor element, and a defective pixel detection unit for detecting the defective pixels, and irradiating the imaging region when detecting the defective pixels The address information of the defective pixel detected from the captured image in the first illuminance state in which the illuminance of the light is low is stored, and the address detected from the captured image in the second illuminance state in which the illuminance is higher than the first illuminance state A defective pixel address storage unit for storing information; an address comparison unit for comparing address information of the defective pixel in the first illuminance state and the second illuminance state stored in the defective pixel address storage unit; It is achieved by a detection apparatus comprising a correction address determination unit that determines a correction address to be executed for a defective pixel based on a comparison of address information of the defective pixel. .

  In addition, the object of the present invention is a detection method for detecting a defective pixel generated in an imaging region of a semiconductor element, wherein a first illuminance state in which the illuminance of light irradiating the imaging region is low when the defective pixel is detected. The address information of the defective pixel detected from the captured image and the address information detected from the captured image of the second illuminance state in which the illuminance is higher than the first illuminance state are stored in the defective pixel address storage unit, Correction performed on the defective pixel based on the comparison of the address information of the defective pixel by comparing the address information of the defective pixel in the first illuminance state and the second illuminance state stored in the address storage unit This is achieved by a detection method characterized by determining an address.

  According to the present invention, it is possible to acquire defective pixel address information by changing the illuminance, compare the respective address information, change the transfer efficiency according to the irradiation amount, and specify the defective pixel whose address changes. Based on the comparison of the defective pixel address information, a correction address to be executed on the defective pixel can be determined. For example, for a defective pixel that forms a point flaw that does not change the transfer efficiency even when the illuminance is changed, correction is not performed along the vertical direction as in the past, but only for the address indicated in the address information of the defective pixel. It can be carried out. Therefore, according to the address information of the defective pixel, the defective pixel can be corrected within an appropriate range. By correcting the normal pixel, high-accuracy correction can be performed and the yield can be improved. Can do.

  It is preferable to determine the correction address based on a change in the continuous amount of defective pixels stored in the defective pixel address storage unit. By so doing, it is possible to determine that the defective amount of the continuous pixel is equal to or greater than a predetermined value as a line scratch, and the defective pixel that is equal to or smaller than the predetermined value as a point scratch. Then, by determining the correction address in accordance with the defective pixel, it is possible to perform correction with high accuracy and efficiency without targeting a normal pixel.

  It is preferable to include an illumination that supplies light to irradiate the imaging region, and an illumination control unit that controls the illumination and detects the first illuminance state and the second illuminance state when a defective pixel is detected. If it carries out like this, it can cooperate with a defective pixel detection part at the time of detection of a defective pixel, and can perform the procedure which sets a lighting to the state of predetermined illumination intensity, and detects a defective pixel smoothly.

  ADVANTAGE OF THE INVENTION According to this invention, the defective pixel detection apparatus and detection method which can perform a highly accurate correction | amendment with respect to the defective pixel from which a kind differs according to a signal level can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a detection apparatus according to the present invention.
The detection apparatus 10 has a function of detecting defective pixels generated in the imaging region of the semiconductor element D. In the present embodiment, a description will be given using a solid-state imaging element as an example of the semiconductor element D.

  The detection apparatus 10 acquires an analog output signal from the solid-state imaging device D when detecting a defective pixel and converts the analog output signal into a digital signal, and the digital image converted by the A / D conversion unit 13. A defective pixel detection unit 14 to which a signal is input is provided.

  The defective pixel detection unit 14 detects an output value for each pixel based on the digital signal of the image, determines a pixel whose output value is less than the threshold value as a defective pixel, and sets defective pixel address information to be described later. Output to the pixel address storage. As the address information of the defective pixel, for example, coordinate data representing the position of the defective pixel when an xy plane parallel to the imaging region is defined can be used.

  The detection device 10 is provided with an illumination 11 that irradiates light onto the imaging region of the solid-state imaging device D with a preset illuminance when a defective pixel is detected. Moreover, the illumination control part 12 which can control the illumination 11 and can set to a predetermined illumination state is provided. In the present embodiment, the illumination control unit 12 changes the illuminance of the illumination 11 to a low illuminance state (first illuminance state) where the illuminance of light irradiating the imaging region is low and a medium illuminance state (second illuminance higher than the low illuminance state). Illuminance state). In the present embodiment, the low illuminance state means that the signal output of the solid-state imaging device is supplied from the illumination 11 to the imaging region in a signal level range of 5 to 15% of the charge saturation level with respect to the photodiode of each pixel of the solid-state imaging device. In the middle illuminance state, the signal output of the solid-state imaging device is in a signal level range of 30 to 50% of the charge saturation level with respect to the photodiode of each pixel of the solid-state imaging device.

  The detection apparatus 10 includes a defective pixel address storage unit that stores address information of defective pixels detected by the defective pixel detection unit 14 when a defective pixel is detected. In the present embodiment, as shown in FIG. 1, a defective pixel address storage unit 15 at a low signal level that stores an address of a defective pixel detected from a captured image captured in a low illuminance state, and an image captured in a medium illuminance state. A high signal level defective pixel address storage unit 16 for storing the address of the defective pixel detected from the captured image. In the present embodiment, the defective pixel address storage unit that stores the address information of the defective pixel is divided according to the illuminance state, but may be stored in the same defective pixel address storage unit regardless of the illuminance state.

  The detection device 10 acquires the address information of the defective pixels stored in the defective pixel address storage unit 15 at the low signal level and the defective pixel address storage unit 16 at the high signal level, and compares the acquired address information. An address comparison unit 17 is provided.

  In addition, the detection apparatus 10 includes a correction address determination unit 18 that determines a correction address to be executed for the defective pixel based on the comparison of the address information of the defective pixel in the low illuminance state and the medium illuminance state in the address comparison unit 17. ing. The correction address data determined by the correction address determination unit 18 is output to and stored in the correction address storage unit 19. As the correction address storage unit 19, for example, a storage unit such as a memory can be used. The correction address storage unit 19 may be another device such as an external personal computer.

  Next, the procedure of the defective pixel detection method according to the present invention will be described. FIG. 2 is a diagram illustrating a procedure of a defective pixel detection method. In the description of the procedure of the detection method, the configuration of the detection apparatus shown in FIG.

  When detecting defective pixels, first, the amount of illumination light is set, and a low illuminance state is set (step S11). Then, the image data is captured by capturing with the solid-state image sensor (step S12).

  After the image data is converted into a digital signal by the A / D converter 13, the defective pixel is detected by the defective pixel detector 14 (step S13). Then, the address information of the detected defective pixel is output to the defective pixel address storage unit. In the detection apparatus 10 of the present embodiment, defective pixels detected in a low illuminance state are stored in the defective pixel address storage unit 15 at a low signal level (step 14).

  Next, the illumination control unit 12 sets the illumination 11 to a predetermined light quantity, sets it to a medium illuminance state (step S15), performs imaging with the solid-state imaging device D, and captures image data (step S16).

  After the image data is converted into a digital signal by the A / D conversion unit 13, the defective pixel detection unit 14 detects the defective pixel (step S17), and outputs the detected defective pixel address information to the defective pixel address storage unit. To do. In the detection apparatus 10 of the present embodiment, the defective pixel detected in the medium illuminance state is stored in the defective pixel address storage unit 16 at the time of a high signal level (step 18).

  After storing the address information of defective pixels in the low illuminance state and the medium illuminance state, the address comparison unit 17 stores the defective pixel address information stored in the low pixel level defective pixel address storage unit 15 and the high signal level defect. The defective pixel address information stored in the pixel address storage unit 16 is output. Then, the address comparison unit 17 compares the address information in the low illuminance state and the address information in the medium illuminance state for the same defective pixel.

The address comparison unit 17 determines a change in the continuous amount of defective pixels based on the comparison of defective pixel address information (step S19). 3 and 4 are diagrams for explaining a change in the continuous amount of defective pixels.
3A shows a defective pixel imaged in a low illuminance state, and FIG. 3B shows a defective pixel imaged in a medium illuminance state. As shown in FIGS. 3A and 3B, when there is no change in the address information of the defective pixels for the defective pixels p11 and p21 in the low illuminance state and the medium illuminance state, the respective defective pixels The continuous amounts Δp1 and Δp2 do not change with respect to the continuous amounts of p11 and p21 with respect to the direction (vertical direction in the figure) of the column that is simultaneously corrected when performing image correction for each vertical column. That is, it is possible to determine that the defective pixels p11 and p21 are point scratches whose transfer efficiency does not change regardless of the illuminance of light. When image correction is performed on these defective pixels p11 and 21, image correction is performed only for the address specified by the address information.

  4A shows a defective pixel imaged in a low illuminance state, and FIG. 4B shows a defective pixel imaged in a medium illuminance state. As shown in FIGS. 4A and 4B, when there is a change in the address information of the defective pixel among the defective pixels p11 and p21 in the low illuminance state and the medium illuminance state, the address information changes. The continuous amount Δp2 of the defective pixel p21 is changed. Specifically, the defective pixel p21 is a defective pixel having the same point scratch as the defective pixel p11 in imaging in the low illuminance state, but when the imaging is performed in the middle illuminance state, the defective pixel p21 is newly detected. As a result, the continuous amount Δp2 is increased.

  The correction address determination unit 18 determines that the defective pixel continuous amount does not change as a defective pixel having a point defect, and outputs the address information of the defective pixel to the correction address storage unit 19. Then, the correction address storage unit 19 sets the defective pixel as a point correction target as a correction address, and stores address information (step S20). On the other hand, the correction address determination unit 18 determines that a defective pixel has a continuous amount of change as a defective pixel having a line defect, and outputs address information of the defective pixel to the correction address storage unit 19. Then, the correction address storage unit 19 sets the defective pixel as a line correction target as a correction address, and stores address information (step S21).

  A process for determining a change in the continuous amount of defective pixels detected in the low illuminance state and the medium illuminance state is executed, and after the correction address is set, the detection of the defective pixel is terminated.

  According to the detection device 10 and the detection method using the detection device of the present embodiment, the address information of the defective pixel is acquired by changing the illuminance, the respective address information is compared, and the transfer efficiency changes according to the irradiation amount. The defective pixel whose address changes can be specified. Based on the comparison of the defective pixel address information, a correction address to be executed on the defective pixel can be determined. In the conventional detection method, defective pixels whose transfer efficiency changes are not discriminated. Therefore, all defective pixels in one vertical column where the defective pixels exist are corrected for all defective pixels. According to the defective pixel detection method of the present invention, for example, a defective pixel that does not change the transfer efficiency even when the illuminance is changed does not perform correction along the vertical direction as in the related art, and the defective pixel is not corrected. Correction can be performed only for the address indicated in the address information. Therefore, according to the address information of the defective pixel, the defective pixel can be corrected within an appropriate range. By correcting the normal pixel, high-accuracy correction can be performed and the yield can be improved. Can do.

  As in this embodiment, if the correction address is determined based on the change in the continuous amount of defective pixels respectively stored in the defective pixel address storage unit, a defective line having a continuous amount of defective pixels equal to or greater than a predetermined value is defined as a line scratch. A defect in which the continuous amount of defective pixels is a predetermined value or less can be determined as a point flaw. Then, by determining a correction address in accordance with each defective pixel, it is possible to perform correction with high accuracy and efficiency without targeting normal pixels.

  Although the detection apparatus 10 of the present embodiment includes the illumination 11 and the illumination control unit 12 that controls the illumination 11, the illumination 11 and the illumination control unit 12 are provided separately from the detection apparatus 10. It is good also as a structure. As in the detection device 10, when the illumination 11 and the illumination control unit 12 that controls the illumination 11 and sets the low illumination state and the medium illumination state when the defective pixel is detected, the defective pixel is detected. At the time of detection, the procedure for detecting defective pixels by setting the illumination 11 to a predetermined illuminance state can be smoothly performed in cooperation with the defective pixel detection unit 14.

It is a figure which shows the structure of the detection apparatus concerning this invention. It is a figure which shows the procedure of the detection method of a defective pixel. It is a figure explaining the change of the continuous amount of a defective pixel. It is a figure explaining the change of the continuous amount of a defective pixel. It is a figure which shows the kind of black crack in the imaging region of a semiconductor element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Detection apparatus 14 Defective pixel detection part 17 Address comparison part 18 Correction address judgment part 19 Correction address storage part D Solid-state image sensor (semiconductor element)

Claims (10)

A detection device for detecting defective pixels generated in an imaging region of a semiconductor element,
A defective pixel detection unit for detecting the defective pixel;
When detecting the defective pixel, the address information of the defective pixel detected from the captured image in the first illuminance state where the illuminance of the light irradiating the imaging region is low is stored, and the illuminance is higher than that in the first illuminance state A defective pixel address storage unit for storing address information detected from the captured image in the second illuminance state;
An address comparison unit for comparing address information of the defective pixel in the first illuminance state and the second illuminance state, which is stored in the defective pixel address storage unit;
A detection apparatus comprising: a correction address determination unit that determines a correction address to be executed for a defective pixel based on a comparison of address information of the defective pixel.   The detection apparatus according to claim 1, wherein the correction address determination unit determines the correction address based on a change in a continuous amount of the defective pixels stored in the defective pixel address storage unit.   And an illumination control unit configured to control the illumination to detect the defective pixel and to set the first illuminance state and the second illuminance state at the time of detecting the defective pixel. The detection device according to claim 1 or 2.   The detection device according to claim 1, wherein the semiconductor element is a solid-state imaging element.   The first illuminance state is a range where the signal output of the semiconductor element is a signal level of 5 to 15% of the charge saturation level, and the second illuminance state is a signal level of 30 to 50% of the charge saturation level. The detection device according to claim 1, wherein the detection device is a range. A detection method for detecting defective pixels generated in an imaging region of a semiconductor element,
At the time of detecting the defective pixel, address information of the defective pixel detected from the captured image in the first illuminance state where the illuminance of the light irradiating the imaging region is low, and the second illuminance is higher than that in the first illuminance state. Store the address information detected from the captured image in the illuminance state in the defective pixel address storage unit,
Compare the address information of the defective pixel in the first illuminance state and the second illuminance state stored in the address storage unit,
A detection method comprising: determining a correction address to be executed for a defective pixel based on a comparison of address information of the defective pixel.   The detection method according to claim 6, wherein the correction address is determined based on a change in a continuous amount of the defective pixels stored in the defective pixel address storage unit.   The detection method according to claim 6 or 7, wherein illumination for supplying light to irradiate the imaging region is controlled and set to the first illuminance state and the second illuminance state.   The detection method according to claim 6, wherein the semiconductor element is a solid-state imaging element.   The first illuminance state is a range where the signal output of the semiconductor element is a signal level of 5 to 15% of the charge saturation level, and the second illuminance state is a signal level of 30 to 50% of the charge saturation level. The detection method according to claim 6, wherein the detection method is a range.

Images