JPH09200626A - Ccd camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image of a television rate by receiving vicinity picture elements or same picture elements simultaneously to compare them, selecting an optimum image to generate an image so to generate one image through pipeline. SOLUTION: Signals from high and low sensitivity sensors 11, 12 are amplified by amplifiers 23a, 23b via a 1st and a 2nd signal lines 21, 22 through a horizontal direction charge transfer part 15. Then sample-and-hold circuits 24a, 24b separate high and low sensitivity signals are separated based on a clock signal of a clock generator 28 obtained by frequency dividing the clock N signal for charge transfer by a transfer section 15. For example, a signal of the line 21 is compared with a reference signal at a comparator 25 so as to discriminate whether or not the signal has a regular lightness and when normal, the signal of the line 21 and when not, the signal of the line 22 is outputted selectively by a switching circuit 27. Furthermore, the signal of the line 22 is restored not to be a low sensitivity via a calibration amplifier 26 and the signal of the line 21 is matched for the level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CCD camera used for image processing using natural light such as machine vision in FA (automated factory) such as visual inspection of electronic parts and automatic monitoring of traffic congestion on roads. . More specifically, the present invention relates to a wide dynamic CCD camera that can obtain a clear image as a whole even if the brightness varies depending on the location (portion) of the subject.

[0002]

2. Description of the Related Art In the field of machine vision in FA and the like, when performing appearance inspection of parts and products by image recognition,
For example, near a window or near an entrance, the brightness of the subject varies depending on the location due to the incident light of the sun. In such a case, the image recognized by the CCD camera is shown in FIG.
As shown in (a), a bright portion A is displayed whitish, and a dark portion C is darkened. Even if the shutter speed is adjusted, a clear image cannot be obtained as a whole, and accurate image processing can be performed. Can not. B indicates a place where the brightness is appropriate.

In order to solve such a problem, for example, Yamada et al. “Wide dynamic range vision, positioning of parts resistant to illumination fluctuation” (7th appearance held at Kogakuin University on November 1-2, 1995) An automated inspection workshop, pages 27 to 32) discloses a method of taking two or more images of the same object having different shutter speeds and recomposing them using a shutter camera. That is, two images, that is, an image P with a slow shutter speed as shown in FIG. 5B and an image Q with a fast shutter speed as shown in FIG. 5C are first read. Since the shutter speed t _{1 of the} image P is slow, the dark portion C of the subject is appropriately recognized, but halation (a state in which the portion is too bright and saturated) is normally bright or is too bright. I'm awake. Further, since the shutter speed t _{2 of} the image Q is too fast, the bright portion A is appropriately recognized, but the too dark portion C is black, and an accurate image cannot be recognized. Therefore, for the portion of the image P where halation occurs, the recognition data of the image Q is used and both of them are combined. At this time, a wide dynamic range is obtained by multiplying the signal of the image P by the ratio of the slow shutter speed t ₁ and the fast shutter speed t ₂ . The shutter speed is 2
Not necessarily the type.

[0004]

The above-described method of synthesizing images having different shutter speeds is not suitable for recognizing a moving object as the images are obtained at different times.

Further, it takes more than two frames to create one screen, and it takes a long time to obtain a final image.

An object of the present invention is to solve the above problems and to provide a CCD camera capable of obtaining a clear image of a subject in which the brightness and darkness of illumination are mixed only by performing image processing on one image pickup screen. .

[0007]

In a CCD camera according to the present invention, a first sensor group in which light-sensitive sensors having high sensitivity (hereinafter, simply referred to as sensors) are arranged in a matrix and a sensor having low sensitivity have high sensitivity. An image pickup unit including a second sensor group arranged adjacent to each sensor, a comparator for comparing an output signal of each sensor of the first sensor group or the second sensor group and a reference signal, and a comparator of the comparator. And a switching circuit that selects either the output of the sensor of the adjacent first sensor group or the output of the sensor of the second sensor group depending on the output.

As means for adjoining the sensor having high sensitivity and the sensor having low sensitivity, the first sensor row in which the respective sensors are arranged continuously in the vertical direction, and the second sensor row
And the third sensor row in which the respective sensors are continuously arranged in the horizontal direction and the fourth sensor row are alternately arranged in the vertical direction. Achieved by In the former case, the number of pixels in the horizontal direction is large, so there is little effect on the image. In the latter case,
This is preferable because the resolution in the horizontal direction can be increased.
In the latter case, the first field charge transfer unit that horizontally transfers the output signals of the odd-numbered sensors of the sensors arranged in the vertical direction and the second field charge transfer unit that horizontally transfers the output signals of the even-numbered sensors. By providing the field charge transfer unit, it is possible to simultaneously process the output signals of the sensor having high sensitivity and the sensor having low sensitivity by using the two-line CCD camera.

Here, the horizontal direction means the horizontal direction which is the direction of the scanning line of the television screen, and the vertical direction means the vertical direction of the television screen which is perpendicular to the horizontal direction.

In another configuration of the CCD camera of the present invention, a splitter for splitting incident light into at least two directions and a highly sensitive sensor provided in each of the split light traveling surfaces are arranged in a matrix. The second imaging unit in which the first imaging unit and the low-sensitivity sensor arranged in a matrix are arranged in a matrix, and the output signal and the reference signal of each sensor of the first imaging unit or the second imaging unit. And a switching circuit that selects either the output of the sensor of the first image pickup unit or the output of the sensor of the second image pickup unit according to the output of the comparator.

Since the calibration amplifier is provided to match the output of the sensor with high sensitivity with the output of the sensor with high sensitivity before the output of the sensor with low sensitivity is input to the switching circuit, the brightness of the screen is accurately measured. It is preferable because it can be corrected to.

Since the sensor with low sensitivity is formed by providing a filter for attenuating light on the surface side of the sensor, the sensor with low sensitivity can be easily obtained by simply increasing one step.

A first A / D converter for converting an output signal from the sensor having high sensitivity into a digital signal, and a second A / D conversion for converting an output signal from the sensor having low sensitivity into a digital signal. Since the comparator and the switching circuit are digital signal processing circuits, the respective signals can be shared.
Two bit A / D converters can output 12 bits and can be constructed with inexpensive equipment.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a CCD camera of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a CCD camera of the present invention, FIG. 2 is a diagram showing a second embodiment of the present invention, FIG. 3 is a diagram showing yet another embodiment, and FIG. 4 is a signal. It is a block diagram which performs a processing part digitally.

In FIG. 1, reference numeral 11 denotes a sensor having a high sensitivity such as a photodiode, and 12 denotes a sensor having a low sensitivity. For example, a filter for attenuating light is provided on the surface side of the photodiode, or the light receiving area of the photodiode is reduced. Alternatively, the shutter time is shortened. Reference numeral 13 denotes a transfer gate that transfers the electric charges of the signals received by the sensors 11 and 12 to the vertical charge transfer unit 14, and the signal charges are transferred to the vertical charge transfer unit 14 and the horizontal charge transfer unit 15 and then the signal processing unit 20. Sent to.

In the structure shown in FIG. 1, the high-sensitivity sensor 11 and the low-sensitivity sensor 12 are continuously provided in the vertical direction, and the first sensor array 1 is provided.
And a second sensor row 2 is formed. The first sensor row 1 and the second sensor row 2 are alternately arranged in the horizontal direction, and a sensor 11 having high sensitivity and a sensor 12 having low sensitivity are adjacently arranged in a matrix. That is, the sensors having the same sensitivity are continuously arranged in the vertical direction, and the sensors having different sensitivities are alternately arranged in the horizontal direction, and the first sensor group of the sensor 11 having high sensitivity and the first sensor group of the sensor 12 having low sensitivity are arranged. Two sensor groups are formed, and the image pickup unit 10 of the camera is formed.

When an image is read by this camera, it can be recognized brightly by the sensor 11 having high sensitivity, and can be recognized clearly even in a dark part of the object. In the sensor 12 having low sensitivity, for example, a gray filter is provided on the surface. Since it is recognized as dark, it is difficult to recognize the dark part of the subject, but it is appropriately recognized even if the subject is too bright. The image signals picked up by both sensors 11 and 12 are
The charges are transferred to the vertical charge transfer unit 14 and the horizontal charge transfer unit 15 as charges, and sent to the signal processing unit 20.

In the signal processing section 20, the sensor 1 having high sensitivity is used.
The signals of 1 and the sensor 12 having low sensitivity are alternately sent via the horizontal charge transfer unit 15. Both of the alternately sent signals are sent to the first signal line 21 for the sensor signal having high sensitivity and the second signal line 22 for the signal having low sensitivity, and are respectively amplified by the amplifiers 23a and 23b. It Then, the sample and hold circuits 24a and 24b pick up only the signals having high sensitivity and the signal having low sensitivity by the clock signal from the clock signal generator 28 obtained by dividing the clock signal for transferring the charges in the horizontal charge transfer section 15. , Separate both signals. Of the separated signals, for example, a part of the signal from the first signal line 21 is branched to generate a reference signal and a comparator 25.
To determine whether the transferred signal has normal brightness. If the signal compared by the comparator is normal, the signal on the first signal line 21 is selected, and if not, the signal on the second signal line 22 is selected by the switching circuit 27 including, for example, a multiplexer and output.

The signal on the second signal line 22 is amplified by the calibration amplifier 26, returned to a state where the sensitivity is not lowered, and adjusted in level with the signal on the first signal line. The calibration amplifier 26 need not be an amplifier if it is corrected in advance according to the ratio of a sensor having a high sensitivity to a sensor having a low sensitivity, but it can be accurately programmed by making the amplifier programmable. You can make adjustments.

In the example shown in FIG. 1, the signal from the sensor having high sensitivity and the signal from the sensor having low sensitivity are separated by using the sample hold circuits 24a and 24b. It may be separated by changing the extraction position from the respective and extracting them separately and inputting them to the first signal line 21 and the second signal line 22. In addition, the comparator 25 uses the second signal line 2
It may be compared with the two signals.

With the above configuration, it is possible to compare the signal levels of the respective pixels provided with the sensor and select a signal of a clear image to use as image data, so that one screen is too bright. Even when a subject having a part and a part that is too dark is photographed, a clear image can be obtained as a whole.

FIG. 2 is an explanatory view of the second embodiment of the CCD camera of the present invention. In FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. This example is different from the example shown in FIG. 1 in that high-sensitivity sensor 11 and low-sensitivity sensor 12 are continuously arranged in the horizontal direction, and third sensor row 3 and fourth sensor row 4 are arranged, respectively. Are arranged alternately in the vertical direction, and two rows of horizontal charge transfer units are provided, which are a first field charge transfer unit 15a and a second field charge transfer unit 15b, respectively. Then, the data of each sensor of the odd-numbered sensor rows of the sensor rows 3 and 4 arranged alternately in the vertical direction is transferred to the first field charge transfer unit 15a, and the data of each sensor of the even-numbered sensor row is transferred to the second field charge transfer section 15a. Part 1
5b.

Originally, there is a time delay between the odd-numbered field and the even-numbered field, but the horizontal charge transfer section should be separated into the first field charge transfer section 15a and the second field charge transfer section 15b. Thus, the signal processing can be performed at the same time by using the two-line output CCD normally used in the television camera. With this configuration, it is possible to increase the resolution in the horizontal direction that is generally performed.

The signal processing of the signal processing unit 20 is the same as in the case of FIG. 1, and similarly, an image can be obtained by the signal that produces a clear image between adjacent sensors.

FIG. 3 is an explanatory diagram of the third embodiment of the present invention. In this example, the sensors arranged in a matrix form a high sensitivity and a sensor having a low sensitivity adjacent to each other to form an image pickup unit. Instead, a plurality of sensors having the same sensitivity are arranged in a matrix and charge transfer is performed. The plurality of image pickup units 6, 7 and 8 also provided with respective units are arranged via a splitter 5 having two built-in spectral prisms, for example, so that one screen can be imaged at the same time. There is a difference in sensitivity between 7 and 8.

In the case of this embodiment, a so-called two-plate C used for three colors of R, G and B in an ordinary color camera.
By using a CD or a three-plate CCD, data of a plurality of screens of different brightness of the same screen can be obtained by the CCD having high sensitivity and the CCD having low sensitivity. As a result, similarly to the above-described example, a clear image of a subject in which light and dark are mixed can be obtained by comparing the data of the same pixels on a plurality of screens and synthesizing the data of the optimum pixel. In addition,
In FIG. 3, reference numeral 9 denotes the outer frame of the camera, and the reference numerals with a, b, and c perform the same functions in the same portions as the reference numerals with the same numerals in FIG. Omit it.

With this configuration, the signals of the adjacent high-sensitivity sensor and the low-sensitivity sensor are not compared and selected, but the same pixel is simultaneously read and compared by the high-sensitivity sensor and the low-sensitivity sensor. Therefore, there is no time and place (pixel) shift, and a clearer image can be obtained.

FIG. 4 is a block diagram of a signal processing unit of still another embodiment of the CCD camera of the present invention. The signal after the signal data is separated into the first signal line 21 and the second signal line 22. The processing is performed with a digital signal. The imaging unit may have any of the configurations shown in FIGS.

Reference numerals 33a and 33b respectively denote first and second A / D converters for converting an analog signal into a digital signal, and 35 denotes a comparator, which is the comparator 2 shown in FIGS.
Performs the same function as 5. A multiplier 36 has the same function as that of the calibration amplifier 26 shown in FIGS. Further, 37 is a switching element, which is the first signal line 21.
Alternatively, one of the signals on the second signal line 22 is selected and output. Since the digital signal is processed by such a configuration, the first and second A / D converters 33a, 3a, 3
Each of 3b can use an inexpensive 8-bit high-speed A / D converter, and exhibits the same effect as 12-bit information processing. This is because the signals processed by the respective A / D converters 33a and 33b are shared with the signal of the first signal line and the signal of the second signal line.

[0031]

According to the present invention, pixels adjacent to each other or the same pixel are simultaneously received and compared, and an optimum image is selected to form a screen. Therefore, one screen is formed by a pipeline. And the images are acquired at the television rate (the process can be done sequentially in one stream and the images can be acquired in real time). In addition, a sensor with low sensitivity can be obtained, for example, by forming a filter film on the surface of a sensor with high sensitivity, and can be manufactured by adding one step of forming the filter film at the end in the same process, and can be obtained at low cost. You can

As a result, a clear screen can be obtained and accurate image processing can be performed even when subjecting a subject whose illumination brightness varies depending on the location.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a CCD camera according to the present invention.

FIG. 2 is a configuration diagram of another embodiment of the CCD camera of the present invention.

FIG. 3 is a configuration diagram of still another embodiment of the CCD camera of the present invention.

FIG. 4 is a configuration diagram of a signal processing unit of still another embodiment of the CCD camera of the present invention.

FIG. 5 is an explanatory diagram of a conventional image of a subject having different brightness.

[Explanation of symbols]

 1 1st sensor row 2 2nd sensor row 3 3rd sensor row 4 4th sensor row 6 Image pick-up part 7 Image pick-up part 8 Image pick-up part 10 Image pick-up part 11 Highly sensitive sensor 12 Low sensitive sensor 15a 1st field Charge transfer unit 15b Second field charge transfer unit 20 Signal processing unit 25 Comparator 26 Calibration amplifier 27 Switching circuit

Claims (7)

[Claims] 1. A first sensor group in which light-receiving sensors with high sensitivity are arranged in a matrix and a light-receiving sensor with low sensitivity in a second sensor group arranged adjacent to the light-receiving sensors with high sensitivity, respectively. An image pickup unit, a comparator for comparing an output signal of each light receiving sensor of the first sensor group or the second sensor group with a reference signal, and an output of the light receiving sensor of the adjacent first sensor group by the output of the comparator Or a switching circuit for selecting one of the outputs of the light receiving sensors of the second sensor group. 2. A first sensor row in which the light receiving sensors having high sensitivity are continuously arranged in the vertical direction, and a second sensor row in which light receiving sensors having the low sensitivity are continuously arranged in the vertical direction. 2. The CCD camera according to claim 1, wherein the light receiving sensor having high sensitivity and the light receiving sensor having low sensitivity are arranged adjacent to each other by alternately arranging in the horizontal direction. 3. A third sensor row in which the light receiving sensors having high sensitivity are continuously arranged in the horizontal direction, and a fourth sensor row in which light receiving sensors having the low sensitivity are continuously arranged in the horizontal direction. Are arranged alternately in the vertical direction so that the high-sensitivity light-receiving sensor and the low-sensitivity light-receiving sensor are arranged adjacent to each other, and the output signals of the odd-numbered light-receiving sensors of the light-receiving sensors arranged in the vertical direction are horizontally arranged. 2. The CCD camera according to claim 1, further comprising a first field charge transfer section for transferring the output signals of the even-numbered light receiving sensors and a second field charge transfer section for transferring the output signals of the even-numbered light receiving sensors in the horizontal direction. 4. A first splitter comprising a splitter for splitting incident light into at least two directions, and a highly sensitive light-receiving sensor provided on each of the split light advancing surfaces arranged in a matrix. A second image pickup section in which an image pickup section and light receiving sensors having low sensitivity are arranged in a matrix; and a comparator for comparing the output signal of each light receiving sensor of the first image pickup section or the second image pickup section with a reference signal. A CCD camera including a switching circuit that selects either the output of the light receiving sensor of the first image pickup unit or the output of the light receiving sensor of the second image pickup unit according to the output of the comparator. 5. The calibration amplifier according to claim 1 or 4, further comprising: a calibration amplifier for adjusting the size of the output of the high-sensitivity light-receiving sensor before the output of the low-sensitivity light-receiving sensor is input to the switching circuit. CCD described
camera. 6. The CCD camera according to claim 1, wherein the light receiving sensor having low sensitivity is formed by providing a filter for attenuating light on the surface side of the light receiving sensor. 7. A first A / D converter for converting an output signal from the light receiving sensor having high sensitivity into a digital signal, and a second A / D converter for converting an output signal from the light receiving sensor having low sensitivity into a digital signal. 5. The CCD camera according to claim 1, further comprising an A / D converter, wherein the comparator and the switching circuit are digital signal processing circuits.