JP4468613B2 - Imaging apparatus and imaging method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for inspecting pixel defects that occur in an image sensor of an imaging apparatus, and more particularly to an imaging apparatus and an imaging method that have a function of inspecting pixel defects that occur later.
[0002]
[Prior art]
A conventional imaging device such as a camera often uses a solid-state imaging device such as a CCD, and an imaging device having a larger number of pixels is manufactured.
[0003]
In a solid-state imaging device formed of a semiconductor such as a CCD, it is known that pixel degradation occurs due to local crystal defects of the semiconductor. A pixel defect in which a constant bias voltage is always added to the imaging output according to the amount of incident light is called a white flaw because it appears as a high-intensity white spot on the monitor if the pixel defect is processed as it is. Yes. Also, those with low photosensitivity appear as black spots and are called black scratches.
[0004]
Therefore, based on pixel defect data (defective pixel position, type, etc.) detected in advance in the inspection process before factory shipment, the data of the defective pixel is replaced with the data created using the data of the surrounding pixels and output. A technique that eliminates the influence of abnormal data due to defective pixels has been proposed (Japanese Patent Laid-Open No. 2000-59799).
[0005]
However, it is known that pixel defects in the image sensor occur due to external factors even after the image sensor is manufactured. Therefore, even after shipment from the factory, it is necessary to have a function that can inspect subsequent pixel defects and eliminate the influence of abnormal data. The inspection function is built into the camera, and this function is used before shooting to detect pixel defects. There has also been a proposal to detect.
[0006]
[Problems to be solved by the invention]
However, since the conventional technique performs inspection within a range that does not affect production efficiency in the inspection process, it may not be practical for mounting on a camera.
[0007]
In particular, it is necessary to consider the timing of inspection after mounting an image sensor on a camera before shipping. For example, it is possible to correct pixel defects by inspecting the soundness of the element before starting imaging, but performing inspection at each imaging start requires unnecessary inspection. For this reason, inconveniences such as delaying the start of photographing may occur. Although it is conceivable to start the inspection according to the instruction of the photographer, it is practically difficult to determine when the photographer should instruct the inspection.
[0008]
The present invention has been made in view of such circumstances, and by performing only when pixel defect inspection is necessary, the soundness of the image sensor can be inspected without hindering imaging, and It is an object of the present invention to provide an imaging apparatus and an imaging method that can determine when a photographer should inspect.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem concerning the later pixel defect, it is necessary to clarify the cause of the pixel defect first.
[0010]
As for external factors that cause CCD defects, various physical quantities have been pointed out, but among them, those caused by cosmic rays have been highlighted. An increasing number of semiconductor manufacturers and engineers point out that many of the soft errors that occur in LSIs, which are memory elements similar to CCDs, are caused by neutrons, charged particles, etc. generated by cosmic rays. NIKKEI ELECTRONICS, (no.667), pp.107-110, (1996)
In addition, it is pointed out that the deterioration of CCD due to cosmic rays becomes more noticeable as the altitude increases, and it is also known that the deterioration of CCDs also progresses depending on the position on the earth due to the well-known fact that cosmic rays weaken in places where the earth's magnetic field is strong. In other words, it can be derived that CCD deterioration is more likely to occur in areas with higher latitudes where the magnetic field is weaker than in the vicinity of the equator where the magnetic field is strong. Broadcast Technology, pp. 115-120, (1995)
The inventor has intensively studied the inspection method with good operability, which is a problem to be solved, through the process of investigating the cause, and as a result, has arrived at the present invention. The problem solving means is as follows. It is.
[0011]
The present invention for solving the problem includes a pixel defect compensation unit that detects and compensates for a pixel defect of an image sensor incorporated in an imaging device, a position detection unit that acquires information relating to a current position of the imaging device, A determination unit that determines that the imaging device has passed a predetermined area based on information relating to the position, and a pixel defect compensation unit that controls compensation of the pixel defect when the determination unit determines that the predetermined area has been passed. And an image pickup apparatus provided with a control means.
[0012]
Further, the present invention is the imaging apparatus according to the above-described invention, wherein the information related to the current position is altitude, and the predetermined area is altitude higher than a predetermined level.
[0013]
According to the present invention, in the imaging apparatus according to the above-described invention, the control unit further includes a start unit that starts the operation of the pixel defect compensation unit when at least one operation of powering on and off the imaging apparatus is performed. An imaging apparatus provided.
[0014]
According to the present invention, in the imaging apparatus according to the above-described invention, as a control unit that replaces the control unit, when the determination unit determines that the predetermined region has been passed, the warning output indicating the occurrence of the deterioration of the image sensor is controlled An imaging apparatus including a control unit.
[0015]
The present invention also provides a position detection step for acquiring information related to the current position of the imaging device, a determination step for determining that the imaging device has passed a predetermined region based on the information related to the current position, and a predetermined step by the determination step. A control step of controlling compensation of pixel defects by pixel defect compensation means that detects and compensates for pixel defects of the image sensor incorporated in the imaging device. is there.
[0016]
The present invention also provides imaging means for reading an imaging signal from an imaging element and generating imaging data for detecting a defect image of the imaging element, and defect information including the size and position of a defect related to a defective pixel from the imaging data. The imaging apparatus includes a detecting means for detecting, an estimating means for estimating the damage deterioration state of the LSI due to cosmic rays from the defect information, and a display means for displaying and outputting the estimation result.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to the present invention.
[0018]
First, the operation of the apparatus in normal shooting will be described. In the description of the embodiments, descriptions of parts that are not essentially necessary for the present invention are omitted, but this does not limit the scope of the present invention.
[0019]
The optical image of the subject that has passed through the lens 2 via the light shielding filter 1 is converted into an electrical signal by the image sensor 3 and converted into an analog image signal. Subsequently, after operating the drive unit 5 under the control of the central processing unit 4 to close the light shielding filter 1, the analog image signal is read out in synchronization with the timing signal from the synchronization signal generating unit 6, and the A / A The digital image signal is converted by the D conversion unit 7 and stored in the memory 8.
[0020]
Subsequently, pixel defect data storing information such as the position of the defective pixel, the defect state (defect type, etc.) is read from the defect data memory unit 9. Then, pixel defect processing is performed on the digital image stored in the memory 8 by a predetermined algorithm such as replacing data at a position where the defective pixel exists with data created using surrounding pixel data.
[0021]
The digital signal of the image thus corrected is compressed into a JPEG format or the like by a conversion process (not shown), stored in the memory card unit 10, and displayed and output on the display unit 11 such as a liquid crystal monitor.
[0022]
These series of operations are managed and controlled by the central processing unit 4.
[0023]
Next, an operation for inspecting a pixel defect in the imaging apparatus having such a configuration will be described.
[0024]
When the pixel defect inspection operation is started, the central processing unit 4 operates the drive unit 5 to drive the light shielding filter 1 to close the image sensor 3 so that the image sensor 3 is shielded from light.
[0025]
The captured image (black image) is converted into a digital image signal in the memory 8 by the above-described imaging procedure and stored as imaging data.
[0026]
Subsequently, the central processing unit 4 reads out the imaging data and determines whether or not a pixel has a defect according to a predetermined algorithm.
[0027]
When it is determined that a defect has occurred by specifying a defect occurrence position and a defect state such as a defect type by a predetermined algorithm, the defect data stored in the defect data memory 9 is read and newly detected. The defect position and defect state thus stored are additionally stored in the defect data memory 9.
[0028]
In this way, by reflecting the detected result in the defect data memory 9, it is possible to correct the image with high accuracy.
[0029]
Regarding the defect detection method, the white defect can be detected by inspecting an image taken with the light shielding filter 1 closed and the image sensor 3 shielded as in the present embodiment. The present invention is not limited to white defects. For example, if an image obtained by photographing a subject with uniform brightness is inspected, a black defect can be detected.
[0030]
Next, a method for determining the necessity of inspection will be described.
[0031]
In the image pickup apparatus of the present invention, when the image pickup operation is not performed, the function of the central processing unit 4 obtains information from the position detection unit 12 without being limited to the on / off state of the apparatus power supply, or It is assumed that the operation for monitoring the state of the position detection unit 12 is continued.
[0032]
FIG. 2 is a schematic flowchart for explaining the first embodiment of the monitoring operation of the central processing unit.
[0033]
In the present embodiment, the position detector 12 includes an altitude measuring sensor.
[0034]
First, the central processing unit 9 reads the value of the altitude measurement sensor (S1), indicates an altitude that is higher than a predetermined value (S2), and monitors that the state continues for a predetermined time (S3).
[0035]
That is, it can be considered that the cosmic rays are greatly affected when the vehicle is at a high altitude.
[0036]
If the conditions of S2 and S3 are satisfied, it is determined that there is a possibility that the image sensor 3 has deteriorated due to the influence of cosmic rays (S4), and the flag for inspection is turned on (S5). .
[0037]
When the conditions of S2 and S3 are not satisfied, the time during which the user has stayed at a high level is accumulated in a predetermined storage area (S6) and used for future determination data.
[0038]
Here, the altitude measuring sensor may be constituted by an atmospheric pressure measuring sensor used for a wristwatch or the like, for example.
[0039]
Further, the present invention is not limited to the form in which the altitude measuring sensor is incorporated in the imaging apparatus, and conversely, a wristwatch or the like may be provided with an imaging function. This is because in any form, it is necessary to determine the deterioration of the image sensor.
[0040]
In the present embodiment, not only the altitude but also the time elapse condition is determined. However, the present invention is not limited to this example, and it can be determined that the image sensor 3 is deteriorated only under the altitude.
[0041]
FIG. 3 is a schematic flowchart for explaining the second embodiment of the monitoring operation of the central processing unit.
[0042]
In the present embodiment, the position detection unit 12 includes a position measurement sensor.
[0043]
First, the central processing unit 9 reads position information from the position measurement sensor (S11), and specifies the current position from this information (S12). Then, it is monitored whether the latitude representing the specified position satisfies a predetermined condition (S13) and continues in the area for a predetermined time or more (S14).
[0044]
In other words, if you are in an area with a high latitude, it is considered that you are greatly affected by cosmic rays.
[0045]
Therefore, when the conditions of S13 and S14 are satisfied, it is determined that there is a possibility that the image pickup device 3 is deteriorated due to the influence of cosmic rays (S15), and the flag requiring inspection is turned on (S16). .
[0046]
When the conditions of S13 and S14 are not satisfied, the time staying in the area is accumulated in a predetermined storage area (S17) and used for future determination data.
[0047]
Here, the position measurement sensor may be constituted by GPS, for example, and the position detection unit 12 receives position information from an external processing device even if it does not calculate the position by processing the GPS signal itself. Also good. In addition, the present invention is not limited to a mode in which a GPS processing function is incorporated in an imaging apparatus, and conversely, a mobile information terminal, a mobile phone, or the like having a GPS function may be provided with an imaging function. This is because in any form, it is necessary to determine the deterioration of the image sensor.
[0048]
In the present embodiment, not only the position but also the time lapse condition is determined. However, the present invention is not limited to this example, and it can also be determined that the image sensor 3 is deteriorated only under the position condition.
[0049]
FIG. 4 is a schematic flowchart for explaining the third embodiment of the monitoring operation of the central processing unit.
[0050]
In the present embodiment, the position detector 12 has a world clock function.
[0051]
First, the central processing unit 9 reads the city code when displayed on the world clock (S21), and monitors that the displayed city code has been changed (S22).
[0052]
That is, when the city code is changed, it is determined that there is a high possibility that the imaging apparatus has been transported across the border, and in that case, it is presumed that it has been transported by an aircraft.
[0053]
If the condition of S22 is satisfied, it is determined that there is a possibility that the image pickup device 3 has deteriorated due to the influence of cosmic rays because the image pickup apparatus has passed an altitude of a predetermined level or more by the aircraft (S23). The inspection flag is turned on (S24).
[0054]
If the condition of S22 is not satisfied, the process ends as unnecessary.
[0055]
Here, the world clock display method, the time correction method, and the like may be configured in the form of a world clock used in, for example, a wristwatch. Further, the present invention is not limited to a mode in which the world clock function is incorporated in the imaging apparatus, and conversely, a wristwatch or the like may be provided with an imaging function. This is because in any form, it is necessary to determine the deterioration of the image sensor.
[0056]
FIG. 5 is a schematic flowchart for explaining the pixel defect inspection and compensation operations.
[0057]
When the power source of the image pickup apparatus is turned on (S31), first, processing related to pixel defect inspection is activated, and it is investigated whether or not the inspection necessity flag is turned on (S32).
[0058]
If the inspection required flag is on, the pixel defect detection operation is performed according to the above-described procedure (S33), and the defect data detected as a result is stored in the defect data memory 9 (S34). Then, the related data such as the inspection required flag is reset to return to the initial state (S35).
[0059]
Subsequently, photographing preparation processing such as recognizing the memory card 10 and driving the lens 2 to the initial position is performed (S36). Then, when the photographer presses the shutter, photographing processing such as aperture driving and data capture into the image sensor 3 is performed, and pixel defects are compensated for the captured image according to the above-described procedure (S37). .
[0060]
The image thus corrected is recorded on the memory card 10 or on the display unit 11 (S38). Thereafter, when the photographer turns off the power of the imaging apparatus, a photographing end process such as lens storage is performed.
[0061]
In this embodiment, the inspection operation is started when the camera is turned on. However, the present invention is not limited to this mode, and the inspection operation is started after the photographer turns off the camera. Also good. At this time, the operation may be started before the photographing end process, or the operation may be started after the photographing end process.
[0062]
With the configuration described above, since it is possible to automatically start when it is determined that a pixel defect inspection is necessary, the operation is simpler and does not hinder photographing as compared with the method of performing the inspection every time. Inspection can be performed.
[0063]
In this embodiment, the inspection is automatically started. However, the present invention is not limited to this embodiment, and the determination result indicating that the inspection is necessary is displayed on the display unit 11 or a warning lamp (not shown) is turned on. Thus, the photographer can be prompted to perform an inspection start operation, and the photographer can manually perform the inspection start operation. If comprised in this way, the photographer can grasp | ascertain the timing which should be test | inspected.
[0064]
Further, the photographer can take various measures based on the determination result.
[0065]
If the imaging device 3 is deteriorated due to the influence of cosmic rays, it can be assumed that this also affects the influence of cosmic rays on memories such as LSIs incorporated in the same device. it can. Although it is difficult to directly measure the LSI damage degradation status, if the pixel degradation status is quantitatively grasped by the pixel degradation inspection technology of the image sensor, the quantified value and the LSI damage degradation status can be obtained. By associating in advance, it is possible to estimate the damage deterioration status of the LSI.
[0066]
By doing so, it is possible to prevent the occurrence of a soft error or the like by taking measures such as replacement in advance.
[0067]
In addition, since the image pickup device holds the state of exposure by cosmic rays as a history, the pixel deterioration state can be handled as monitoring the cumulative value of exposure.
[0068]
As described above, various measures can be taken if the result of the inspection of the degree of damage of the image sensor is output by display or the like.
[0069]
【The invention's effect】
As described above, according to the present invention, the soundness of the image sensor can be inspected without hindering photographing, and the timing at which the photographer should inspect can be determined.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to the present invention.
FIG. 2 is a schematic flowchart for explaining a first embodiment of a monitoring operation of a central processing unit.
FIG. 3 is a schematic flowchart for explaining a second embodiment of the monitoring operation of the central processing unit.
FIG. 4 is a schematic flowchart for explaining a third embodiment of the monitoring operation of the central processing unit.
FIG. 5 is a schematic flowchart for explaining pixel defect inspection and compensation operations;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 3 ... Image sensor 4 ... Central processing part 5 ... Drive part 6 ... Synchronous signal generation part 8 ... Memory 9 ... Defect data memory 11 ... Display part 12 ... Position detection part

Claims (6)

Pixel defect compensation means for detecting and compensating for pixel defects in the image sensor incorporated in the imaging device;
Position detecting means for acquiring information relating to the current position of the imaging device;
Determining means for determining that the imaging device has passed a predetermined area based on information on the current position;
An image pickup apparatus comprising: a control unit that controls compensation of a pixel defect by the pixel defect compensation unit when the judgment unit determines that a predetermined area has been passed. The information related to the current position is altitude,
The imaging apparatus according to claim 1, wherein the predetermined area has an altitude that is equal to or higher than a predetermined level. 3. The control unit according to claim 1, further comprising a start unit that starts an operation of the pixel defect compensation unit when at least one operation of turning on and off the power of the imaging apparatus is performed. The imaging device described in 1. The control means for replacing the control means, comprising control means for controlling a warning output indicating the occurrence of deterioration of the image sensor when the judgment means judges that a predetermined area has been passed. The imaging apparatus according to 1 or 2. A position detection step of acquiring information relating to the current position of the imaging device;
A determination step of determining that the imaging device has passed a predetermined area based on information on the current position;
A control step of controlling compensation of pixel defects by pixel defect compensation means that detects and compensates for pixel defects of an image sensor incorporated in the imaging device when it is determined by the determination step that a predetermined region has been passed; An imaging method comprising: Imaging means for reading an imaging signal from the imaging element and generating imaging data for detecting a defect image of the imaging element;
Detection means for detecting defect information including the size and position of a defect related to the defective pixel from the imaging data;
Estimating means for estimating the damage deterioration status of LSI due to cosmic rays from the defect information;
An image pickup apparatus comprising: a display unit that displays and outputs the estimation result.

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