JP2007027844A - Imaging apparatus having pixel defect complementary function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus having a pixel defect complementary function that has an extremely simple circuit as compared with a conventional method for complementing a pixel defect in an image pickup device by a peripheral pixel signal, and can obtain an image where a change in incident light is reproduced faithfully. <P>SOLUTION: The imaging apparatus comprises a dispersing means for dispersing the incident light from an objective lens to a plurality of systems, an image pickup device provided at each image-forming position in the incident light dispersed to the plurality of systems, a drive means for driving the image pickup device in-phase, and a signal processing means for complementing one photoelectrically converted output signal of the image pickup device by the other output signal. By the signal processing means, the pixel signal of one output signal is substituted for that of the other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly, to an imaging apparatus having a pixel defect complementation function for complementing pixel defects of an imaging element.

  When the output signal of the image sensor is displayed on the display, white spots, white lines, black spots, black lines, uneven brightness, or the like may be observed in the image. These are called image defects (pixel defects) or image defects.

  The causes of image defects can be broadly divided into those caused by the semiconductor substrate (wafer) itself used and those introduced during the device manufacturing process.

  These image defects, even small ones, are very noticeable and cause various obstacles in application.For example, in semiconductor wafer quality inspection, due to the dark illumination environment, the accumulation time is increased and the circuit gain is increased to increase the sensitivity. In the image pickup apparatus for inspecting scratches and the like, pixel defects and S / N (signal / noise ratio) of the image pickup element have been problems.

  In order to solve the above problem, in the conventional example, a prism that supplements the surrounding pixel signal or condenses the light rays from the subject with a lens and divides the condensed light rays into a plurality of paths is provided. Light is simultaneously received by the CCD plate disposed at the imaging position of each light beam, and the converted analog signal is added after S / H (sample hold) conversion is performed on the output signal of the received CCD plate. A common timing generator is provided for taking out as one image output signal.

In the conventional example configured as described above, each analog signal is added and extracted as one image output signal. Therefore, the image output signal is doubled and the amplification factor of the inherent noise level is 2. S / N is improved because it is held below the square root.
Japanese Patent Laid-Open No. 6-165043

  However, in the above-described conventional example, a complicated circuit is required to complement the surrounding pixel signals. In addition, in the method in which each analog signal is simply added and extracted as one image output signal, S / N is improved, but, for example, black scratches that are output when a pixel on the CCD plate loses the photoelectric conversion function are not completely compensated, and are corrected to ½ or less of the normal output. In some cases, there was a problem that white scratches were more emphasized.

The inventor of the present application has solved the above problems by the following means.
(1) Spectroscopic means for splitting incident light from the objective lens into a plurality of systems, an image sensor disposed at each imaging position of the incident light split into the plurality of systems, and the image sensor in the same phase Drive means for driving, and signal processing means for complementing one output signal photoelectrically converted by the image sensor with the other output signal,
An image pickup apparatus having a pixel defect complementation function, wherein the signal processing means includes a pixel defect complement circuit that replaces a pixel signal of the one output signal with the other pixel signal.

(2) The signal processing means further includes a storage means for storing pixel defect position information of the image pickup element to be replaced, and has the pixel defect complementing function described in (1) above Imaging device.

(3) The signal processing unit extracts a pixel signal from the output signal based on the pixel defect position information of each of the imaging elements read from the storage unit, and the pixel of the one output signal according to the pixel defect position information An image pickup apparatus having a pixel defect complementing function according to item (2), further comprising a pixel defect complementing circuit that replaces each signal with the other pixel signal.

(4) The signal processing means includes two signal output circuits in which the pixel signal of the one output signal is replaced with the other pixel signal, and one image of the image output signals of the two signal output circuits An image pickup apparatus having a pixel defect complementing function according to any one of (1) to (3) above, further comprising a signal correction circuit that adds the output signal and the other image output signal.

The following effects are exhibited by the present invention.
1. According to the invention of claim 1 of the present application,
Since the signal processing means includes a pixel defect complement circuit that replaces the pixel signal of the one output signal with the other pixel signal, a white spot, white line, black spot, black line, or brightness in one image Even if there is a pixel defect such as samurai, an image having no pixel defect can be obtained by replacing the other normal pixel signal.

  In addition, even if there is a pixel defect such as white spot, white line, black spot, black line or uneven brightness in one image and photoelectric conversion according to incident light is not performed, photoelectric conversion is performed according to the change in incident light. Since the pixel signal is replaced with the other normal pixel signal, it is possible to obtain an image in which a change in incident light is faithfully reproduced with a very simple circuit as compared with the conventional method of complementing with a surrounding pixel signal.

2. According to the invention of claim 2 of the present application,
In addition to the effect of the first aspect, for example, in a semiconductor wafer quality inspection or the like in a dark illumination environment, the storage time is increased and the circuit gain is increased to detect a scratch or the like with high sensitivity. A method for detecting a pixel defect and complementing a flaw by detecting a pixel defect each time causes a flaw detection error. However, the signal processing unit stores pixel defect position information of the image sensor to be replaced. If the pixel defect position information is stored in the storage means at the initial setting stage, the pixel defect position can be specified under any imaging state, so that an image in which the pixel defect is accurately complemented is obtained. be able to.

3. According to the invention of claim 3 of the present application,
In addition to the effect of the second aspect, the signal processing unit extracts a pixel signal from the output signal based on the pixel defect position information of the imaging element read from the storage unit, and according to the pixel defect position information. Since a pixel defect complement circuit that replaces the pixel signal of the one output signal with the other pixel signal is provided, the output signal from the image sensor in an imaging state having an extremely bad S / N as described above. However, it is possible to obtain an image in which pixel defects are accurately replaced according to the stored pixel defect position information.

4). According to the invention of claim 4 of the present application,
In addition to the above effect, the signal processing means includes two signal output circuits in which the pixel signal of the one output signal is replaced with the other pixel signal, respectively, and the image output signals of the two signal output circuits Since the signal correction circuit for adding one image output signal and the other image output signal is provided, the image output signal is doubled, and when this is attenuated to the rated value, the amplification factor of the inherent noise level is 2 S / N is improved because it is held below the square root of.

The best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an image pickup apparatus having a pixel defect complementing function according to the present invention.
In the figure, 1 is an imaging device, 2 is an objective lens, 3 is a spectroscopic means, 4 is a half mirror, 5 is a solid-state imaging device, 6 is a CCD driving means, 7 and 7 ': CDS circuit & VGA circuit, and 8 is An A / D circuit, 9 is signal processing means, 10 is storage means, 11 is a pixel defect complement circuit, 12 and 12 'are signal output circuits, 13 is a signal correction circuit, and 14 is an output terminal.

  In FIG. 1, a spectroscopic unit 3 that splits incident light from the objective lens 2 into two systems, and solid-state imaging devices 5 and 5 ′ disposed at respective imaging positions of the incident light split into the two systems. CCD driving means 6 for driving the solid-state image pickup devices 5 and 5 ′ in the same phase, and a CDS (correlated double sampling) circuit for signal-processing the photoelectrically converted video output signals of the solid-state image pickup devices 5 and 5 ′, respectively. & VGA (video amplification) circuits 7, 7 ', A / D circuit 8 for analog-digital conversion, signal processing means 9 for complementing one video output signal with the other video output signal, solid-state imaging device 5, The imaging device 1 having a pixel defect complementation function is configured with the storage unit 10 that stores the pixel defect position information of 5 ′.

  Further, the signal processing means 9 has a pixel defect complement circuit 11 that replaces the pixel signal of one video output signal with the other pixel signal, and the pixel signal of one video output signal is replaced with the other pixel signal, respectively. Two signal output circuits 12, and a signal correction circuit 13 for adding the image signal of one output signal of the two signal output circuits 12 and the image signal of the other output signal.

  An optical image of a subject imaged by the objective lens 2 is provided with a solid-state imaging device 5, 5 ′ at the imaging position of the optical image that is divided into two systems by the spectroscopic means 3 with a built-in half mirror 4. Yes.

  The two solid-state imaging devices 5 and 5 ′ are preliminarily aligned with a solid-state imaging device attaching jig capable of fine adjustment of six-axis control such as a spatial position, rotation, and tilt, and then an adhesive or Bonding work for fixing with solder is performed and the spectroscopic means 3 is integrated.

  The two solid-state imaging devices 5 and 5 'are driven with the same phase by a common CCD driving means 6 by a clock based on a predetermined scanning method.

  Here, when the optical image split by the half mirror 4 and imaged on the solid-state imaging device 5 ′ is reversed left and right, the scanning of the solid-state imaging device 5 ′ employs a mirror readout method, and the optical image is inverted upside down. In this case, it is preferable to add a total reflection mirror or the like after the spectroscopy by the half mirror 4 and project a re-inversion image on the solid-state imaging device 5 ′.

  Therefore, the photoelectrically converted video signals output from the two solid-state imaging devices 5 and 5 ′ are output at the pixel position where the horizontal and vertical spatial positions match.

  The video signals photoelectrically converted by the solid-state imaging devices 5 and 5 ′ are converted into digital signals by the A / D circuit 8 via the CDS circuits & VGA circuits 7 and 7 ′, respectively, and the pixel defect complementing circuit of the signal processing means 9 is used. 11 is input.

  The pixel defect complement circuit 11 reads out pixel defect position information with a pixel defect from the storage means 10 in which pixel position information with a pixel defect is stored in advance at the initial setting stage, and according to the pixel defect position information, The pixel signal having a pixel defect in the output signal is discarded and replaced with the other pixel signal having no pixel defect.

  Further, the pixel defect complementing circuit 11 performs signal processing for replacement with pixel signals having no pixel defect on both video output signals and inputs them to the respective signal output circuits 12 and 12 '.

  The image output signals without pixel defects output from the signal output circuits 12, 12 'are added by the signal correction circuit 13, further controlled to a normal signal level of 1/2, and output from the output terminal 14 to the outside. As a result, the amplification factor of the inherent noise level is suppressed to a square root of 2 or less, so that the S / N is improved.

  Pixel defects in the solid-state imaging device of the present invention are compensated based on the condition that they do not occur at the same horizontal and vertical spatial positions at the same time.

In the above embodiment,
Moreover, it is not limited to a solid-state image sensor, A vacuum tube system or a similar image sensor may be used.

  Further, in the present embodiment, only the objective lens is simply shown in the lens system, and an infrared cut filter disposed on the incident surface side of the spectroscopic optical system, an optical filter disposed on the incident surface side of the solid-state imaging device, etc. These optical members are not shown, but are omitted because they are not directly related to the gist of the invention, and these are naturally used as necessary.

  In addition, although it demonstrated using the spectroscopic means to divide into two lines, it is not restricted to this and you may use three or more lines of spectroscopic means.

  It has a pixel defect complement circuit that replaces the pixel signal of one output signal of the image sensor with the other pixel signal, and there is a pixel defect such as white spot, white line, black spot, black line, or uneven brightness in one image. However, it is an imaging device that has a pixel defect complementation function that can be replaced with the pixel signal of the other normal imaging element and can obtain an image that has no pixel defects and faithfully reproduces the change in incident light. It can be used as an imaging device for inspecting various kinds of scratches such as wafer quality inspection.

The block diagram of the Example of the imaging device provided with the pixel defect complementation function of this invention.

Explanation of symbols

1: imaging device 2: objective lens 3: spectroscopic means 4: half mirror 5, 5 ': solid-state imaging device 6: CCD driving means 7, 7': CDS circuit & VGA circuit 8: A / D circuit 9: signal processing means 10 : Storage means 11: pixel defect complement circuit 12, 12 ': signal output circuit 13: signal correction circuit 14: output terminal

Claims (4)

Spectroscopic means for splitting the incident light from the objective lens into a plurality of systems, an image sensor disposed at each imaging position of the incident light split into the plurality of systems, and driving for driving the image sensor with the same phase Means, and signal processing means for complementing one of the output signals photoelectrically converted by the imaging device with the other output signal,
An image pickup apparatus having a pixel defect complementation function, wherein the signal processing means includes a pixel defect complement circuit that replaces a pixel signal of the one output signal with the other pixel signal.   2. The image pickup apparatus having a pixel defect complementing function according to claim 1, wherein the signal processing means further comprises storage means for storing pixel defect position information of the image pickup element to be replaced.   The signal processing means extracts a pixel signal from the output signal according to each pixel defect position information of the image sensor read from the storage means, and the pixel signal of the one output signal is extracted according to the pixel defect position information. 3. The imaging device having a pixel defect complementing function according to claim 2, further comprising a pixel defect complementing circuit that replaces each pixel signal with the other pixel signal. The signal processing means includes two signal output circuits obtained by replacing the pixel signal of the one output signal with the other pixel signal, respectively, and one image output signal of the image output signals of the two signal output circuits The imaging apparatus having a pixel defect complementing function according to claim 1, further comprising a signal correction circuit that adds the other image output signal.

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