JP2001285719A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device capable of photographing a long and narrow visual field at a high speed without degrading image quality and being manufactured at a low cost. SOLUTION: For the drive control of a two-dimensional image pickup element for which a photosensitive pixel area where the specified horizontal line band of a width sufficiently narrower than the total number of horizontal lines is surrounded by optical black pixels is formed, at the beginning of each vertical period, a signal charge fetch processing from light receiving pixels to the vertical shift registers of respective columns, a preceding stage optical black pixel area coping processing for dropping signal charges on the vertical shift registers of the respective columns fetched from a preceding stage optical black pixel area to a horizontal shift register and a photosensitive pixel area coping processing for reading the signal charges on the vertical shift registers of the respective columns fetched from the photosensitive pixel area to the outside by appropriately linking the transfer of the vertical shift registers of the respective columns and the transfer of the horizontal shift register are repeated without interposing the post stage optical pixel area coping processing of an operation similar to a preceding stage in the middle and a one-screen read cycle is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement sensor,
The present invention relates to an imaging device suitable for a visual measurement device requiring an elongated field of view, such as a D sensor, a length measurement sensor, and a barcode reader, and more particularly to an imaging device suitable for high-speed imaging and capable of being manufactured at low cost.

[0002]

2. Description of the Related Art In recent years, there has been a demand for using a two-dimensional image sensor instead of a conventional one-dimensional image sensor or PSD for a visual measurement device such as a displacement sensor, a 3D sensor, a length measurement sensor, and a bar code reader. is there. For example, if a two-dimensional image sensor is used as a displacement sensor to which the light-section method is applied, not only displacement information but also the image itself of the measurement object or the spot shape of the measurement beam can be confirmed. For example, in a bar code reader or the like, for a light receiving pixel array in a direction orthogonal to the light receiving pixel array direction corresponding to the code arrangement direction, for example, in a bar code reader or the like, appropriate processing such as integration processing and peak extraction processing is performed. By applying image processing technology, it is expected that a new function (improvement in detection sensitivity, etc.) will be added to this type of visual measurement device.

By the way, as a two-dimensional image pickup device used in an image pickup device having a built-in visual measurement device of this kind, a relatively inexpensive popular two-dimensional image pickup device is used from the viewpoint of cost reduction. The light-receiving pixel array of such a popular two-dimensional image sensor generally corresponds to a view aspect ratio of a standard image pickup device (for example, a general-purpose digital still camera, a video camera for TV or HDTV). Have been.

FIG. 1 shows an example of a light receiving pixel array of a CCD image pickup device for a digital still camera which is a popular two-dimensional image pickup device.
This is schematically shown in FIG. It should be noted that, for convenience of explanation, the size of the light receiving pixel is exaggerated considerably from the actual size.

In FIG. 1, Ph represents each light-receiving pixel of a light-receiving pixel group arranged in a matrix of 788 rows in the vertical direction and 1077 columns in the horizontal direction, corresponding to the field of view of a standard imaging device.
VR (VR1 to VRn) are n (in this example, n = 1077) vertical shift registers for transferring the output of each light receiving pixel Ph constituting the light receiving pixel group in the vertical direction for each column;
HR is a horizontal shift register that receives charges transferred from the vertical shift registers VR of each column and transfers the charges in the horizontal direction. Aout is a horizontal shift register HR.
This is an output buffer for outputting the charges transferred from the device to the outside.

[0006] Among the light receiving pixels Ph, the light receiving pixels Ph1 shown in white in the figure are photosensitive pixels, and the light receiving pixels Ph2 shown in hatching in the figure are optical black pixels. Those light receiving pixels Ph1, P
Each of h2 has an element structure based on a photodiode or a phototransistor. The vertical and horizontal shift registers VR, HR have a CCD-based element structure.

[0007] As is well known to those skilled in the art, the optical black pixel Ph2 cannot be received with a light-shielding mask, does not accumulate charge even when light is received by a manufacturing process, or is accumulated by light reception. It is a light receiving pixel whose element structure is modified so that electric charge cannot be taken out, and its output is always at a specified dark level regardless of the amount of received light. The light-sensitive pixel Ph1 is a normal light-receiving pixel to which no such special modification has been made, and its output has a light level corresponding to the amount of received light.

In the example of FIG. 17, the light receiving pixels Ph (m, n) ｛m = 1 to 788, n = 1 to 10 which constitute the light receiving pixel group
In 77 °, the light receiving pixels belonging to seven horizontal lines (meaning horizontal pixel columns) near the upper edge of the screen and the light receiving pixels belonging to two horizontal lines near the lower edge of the screen are all optical black pixels Ph2. It has been. Most of the light receiving pixels Ph belonging to the 779 horizontal lines located at the center between the seven horizontal lines at the upper edge and the two horizontal lines at the lower edge are the photosensitive pixels Ph1.

Strictly speaking, among the light receiving pixels Ph belonging to the 779 horizontal lines at the center, light receiving pixels Ph belonging to three vertical lines (meaning vertical pixel columns) near the left edge of the screen. The light receiving pixels Ph belonging to the 40 vertical lines near the right edge of the screen are all optical black pixels Ph2.
It has been. 1 is located at the center between the three vertical lines on the left edge and the 40 vertical lines on the right edge.
The pixels Ph belonging to the 034 vertical lines are all light-sensitive pixels Ph1.

FIG. 18 shows the relationship between the size of the photosensitive pixel area and the size of the optical black pixel area in the CCD image pickup device (for a digital still camera) in terms of the actual screen aspect ratio. As shown in the figure, as shown in FIG.
79 rows × 1034 columns) correspond to the entire light receiving surface (788 rows × 1034 columns).
77 columns).

In such a CCD image pickup device, when a first transfer pulse (see TP1 in FIGS. 19 and 20) is given from the outside, the output of the light receiving pixel Ph belonging to each vertical line (in the case of the photosensitive pixel Ph1, The accumulated charge during the electronic shutter open period, or, in the case of the optical black pixel Ph2, almost zero charge corresponding to a prescribed dark level) is transferred to the corresponding stage of the adjacent vertical shift register VR. When a second transfer pulse (see TP2 in FIGS. 19 and 20) is applied from the outside, each vertical shift register VR is shifted upward by one stage in the figure, and each vertical shift register V
The charge stored in the first stage of R is transferred to the corresponding stage of the horizontal shift register HR. When a third transfer pulse (see TP3 in FIGS. 19 and 20) is applied from the outside, the horizontal shift register HR is shifted by one stage to the left in the figure, and the charge stored in the first stage of the horizontal shift register HR Are output to the outside via the output unit Aout.

In FIG. 20, each of the first to third transfer pulses TP1 to TP3 is depicted as a single-phase one pulse.
TP3 is often composed of multiphase pulses. Therefore, when it is composed of polyphase pulses,
The expression one pulse is to be understood as meaning a series of multi-phase pulses equivalent to one single-phase pulse.

FIG. 20 shows the format of the video signal obtained from the two-dimensional image pickup device.
In the drawing, the output data for one line of the video signal (upper stage) for each vertical period includes a numerical value indicating which line of the light receiving pixel Ph corresponds to the data, and the output data for each horizontal period. The output data of one light receiving pixel of the detailed video signal (lower) is assigned an address indicating the coordinates of the light receiving pixel Ph corresponding to the data.

First, the first vertical period is started, and the first transfer pulse TP1 is output during the vertical blanking period. The transfer pulse TP1 is applied to each of the light receiving pixels Ph at the same time, and the charges accumulated in each of the light receiving pixels Ph are simultaneously transferred to the corresponding vertical shift registers VR1 to VRn (n = 1077 in this example).

Next, a first horizontal period is started, and each of the vertical shift registers VR1 to VR1 is set within a horizontal blanking period.
A second transfer pulse TP2 is given to Rn. The transfer pulse TP2 causes each of the vertical shift registers VR1 to VR
The signal charges in Rn are shifted one pixel at a time, and the signal charges for the first line (address (1, 1) in the figure)
(1,2)... (Charges corresponding to the (1, n) light receiving pixels) are transferred to the horizontal shift register HR.

Next, until one horizontal period is completed, n third transfer pulses TP3 are continuously supplied to the horizontal shift register HR. As a result, the signal charges for one line accumulated in the horizontal shift register HR are shifted one pixel at a time, and are sequentially output from the foremost charge.

Similarly, a transfer pulse TP2 is applied to each of the vertical shift registers VR1 to VRn for each horizontal period, and signal charges for one line are transferred to the horizontal shift register H.
After the transfer to R, n transfer pulses TP3 are given to the horizontal shift register HR, and the transferred signal charges for one line are output one pixel at a time. One vertical period ends when the horizontal period is repeated m times (m = 788 in this example).

By the way, this kind of CCD image pickup device is used when the entire light receiving surface (horizontal line area) of the CCD image pickup device is used as an effective image area, or when a part of the light receiving surface (specific number of lines) is used. In some cases, only the horizontal line area of a portion is set as the effective image area. The former is, for example, a case of shooting with a general-purpose camera for generating a landscape image, and the latter is, for example, a measuring camera for generating a measuring image that requires a larger resolution in the horizontal direction than in the vertical direction (for example, a displacement sensor, 3D sensor, a length measuring sensor, and a detection head unit of a barcode reader).

In the above-mentioned CCD image pickup device, even in the latter case where an image of the entire light receiving surface is unnecessary, every time one frame is photographed, all charges on all horizontal lines are output to the outside. Or must be discharged. This is because, if the electric charge at the time of photographing the previous frame remains on the vertical or horizontal shift registers VR and HR, a new electric charge is superimposed at the time of photographing the next frame, so-called double photographing occurs. This means that as long as the method of sequentially outputting the charges on all the horizontal lines one by one horizontal line is adopted, and the output time per one horizontal line is fixed, the total number of horizontal lines between successive frames is taken. This means that a constant time proportional to the time is required, which naturally imposes a limit on the frame shooting cycle in continuous shooting.

[0020]

One solution for enabling higher-speed imaging is to reduce the total number of horizontal lines (for example, 60 to 60) to fit such an elongated rectangular field of view for measurement. The use of a dedicated CCD image sensor (about 70 lines). However, such a C
Since the CD imaging device is a custom-made product, the development cost is large and the development period is long, so that it is unavoidable that the cost is increased.

Another solution is disclosed in JP-A-10-191.
As in the image pickup apparatus disclosed in Japanese Patent No. 176, for an image corresponding to an unnecessary portion in the image of the entire light receiving surface, charges for a plurality of horizontal lines are added on a horizontal shift register and output collectively. Is mentioned.

However, even if such a method is employed, the number of horizontal lines that can be added at one time is only a few lines at most, and exceeds the number, because there is a photographed photoreceptor charge in the unnecessary image area. In this case, smear occurs due to charge saturation of the horizontal shift register, which causes image deterioration. Therefore, assuming that the effective image area suitable for the displacement sensor, the 3D sensor, or the like is an extremely elongated effective image area (in other words, most of the unnecessary image area), for example, about 20% of the total number of horizontal lines, It does not contribute to increasing the shooting speed.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to enable a long and narrow field of view to be photographed at high speed without deteriorating the image quality.
In addition, an object of the present invention is to provide an imaging device that can be manufactured at low cost.

Another object of the present invention is to provide a visual processing device capable of acquiring image data at a required resolution at a high speed from a long and narrow field of view and executing a measurement process with a high speed response, and which can be manufactured at low cost. It is an object of the present invention to provide a measuring device (for example, a displacement sensor using a light-section method, a 3D sensor, a length measuring sensor, a barcode reader, and the like).

[0025]

An image pickup apparatus according to the present invention includes a two-dimensional image pickup device having a novel structure proposed by the present inventors, and a dedicated drive control unit for driving the image pickup device. ing.

The two-dimensional image pickup device collectively collects light-receiving pixel groups arranged in a matrix corresponding to the field of view of a standard image pickup device, vertical shift registers of each column, and outputs of the vertical shift registers of each column. A horizontal shift register for receiving the data.

The “standard image pickup device” includes at least
General-purpose digital still cameras and video cameras are included. Looking at current products, there is an example of a two-dimensional imaging device for a digital still camera having a light receiving pixel array of 788 pixels in the vertical direction × 1077 pixels in the horizontal direction. Similarly, as an example of a two-dimensional image projection device for a video camera, 500 rows in the vertical direction × 50 in the horizontal direction
Some have a light receiving pixel array of 0 to 700 columns.

A specific horizontal line band having a width sufficiently smaller than the total number of horizontal lines on the light receiving surface of the two-dimensional image pickup device includes:
By defining the surrounding area as an optical black pixel area, a photosensitive pixel area is formed.

The term "sufficiently narrow" is defined in consideration of an elongated rectangular field of view such as a displacement sensor, a 3D sensor, a length measuring sensor, a bar code reader, etc. in which the element of the present invention is used. . Assuming current products related to displacement sensors and 3D sensors, the number of lines constituting a specific horizontal line band is often less than about 20% of the total number of horizontal lines. If such an elongated visual field can be photographed at high speed while maintaining the resolution in the longitudinal direction, it will be extremely suitable as an image sensor for a displacement sensor, a 3D sensor, a length measuring sensor, and a bar code reader based on the light-section method. . Here, the 3D sensor uses a displacement sensor applied to the light cutting method,
The three-dimensional shape of the surface of the measurement object is measured by acquiring the height information of each part while relatively moving the displacement sensor and the measurement object in a direction perpendicular to the longitudinal direction of the slit beam of the displacement sensor. It is a sensor. The length measurement sensor
Form a slit beam consisting of parallel rays, project this slit beam on the light receiving surface of the two-dimensional image sensor, and measure the length of the shadow area generated on the light receiving surface when the measurement object blocks part of the slit beam. Is a sensor that measures the length of the portion of the target that shields the slit beam.

For example, as a problem of the displacement sensor, since it is not possible to visually recognize the spot light (or slit light) image in the measurement state, there is a concern that the measurement can be performed normally. The use of a two-dimensional image sensor enables a spot light, a raw image of a work, a superposition of a spot light and a raw image, and the like, so that the measurement state can be visually confirmed. Other effects of the displacement sensor include, for example, averaging the image in a direction orthogonal to the longitudinal direction, thereby reducing the influence of a hairline or the like on the work surface and stabilizing the measurement result.

An "optical black pixel" is a light-receiving pixel which has been modified so that light cannot be received by a light-shielding mask, no charge is accumulated even when light is received, or the charge accumulated by light reception cannot be taken out. Thus, the output is always at the prescribed dark level regardless of the amount of received light. On the other hand, a "photosensitive pixel" is a normal light receiving pixel without such special modification, and its output is a light level corresponding to the amount of received light.

The basic functions of the drive control unit are to take in signal charges from the light receiving pixels to the vertical shift registers of each column, to vertically transfer signal charges by the vertical shift registers of each column, and to perform signal transfer by the horizontal shift registers. It controls the horizontal transfer of charges.

More specifically, the drive control section includes a signal charge taking-in process for taking in signal charges from the light receiving pixels to the vertical shift registers of each column at the beginning of each vertical period, and a pre-stage optical black pixel area. The signal charge on the vertical shift register of each column taken from the vertical shift register and the signal charge on the vertical shift register of each column taken from the photosensitive pixel area to drop the signal charge on the vertical shift register of each column into the horizontal shift register The light-sensitive pixel area corresponding process for reading out the external shift by appropriately linking the transfer of the vertical shift register and the transfer of the horizontal shift register of each column to the outside is performed. The process for the post-stage optical black pixel area that causes the signal charges on the shift register to fall into the horizontal shift register And it is configured to repeat without sandwiched.

According to the imaging apparatus having the above-described configuration, the light receiving pixel group belonging to the light sensitive pixel area generates an electric charge corresponding to the amount of received light in response to the light image from the elongated object area to be photographed. The light receiving pixels belonging to the first and second optical black pixel regions are insensitive to light images arriving from other than the elongated subject region to be photographed,
Generates no or little charge.

Of the stages of the vertical shift register in each column, the charge corresponding to the amount of received light is transferred and stored in the stage located in the photosensitive pixel area. No or almost no charge is transferred and stored in the stages located in the first and second optical black pixel regions.

When the drive control unit operates, when all the charges from the photosensitive pixel area have been read following the preceding optical black pixel area, the shutter is immediately started without waiting for the charge to be read from the subsequent optical black pixel area. And overwriting exposure is performed, and thereafter, the reading of charges from the preceding optical black pixel region and the photosensitive pixel region and the overwriting exposure to the charges from the following optical black pixel region are repeated.

At this time, if all the charges in the photosensitive pixel area are read out, the charges in each stage of the vertical shift register belonging to the subsequent optical black pixel area become almost zero. However, the problem of double shooting does not substantially occur.

For this reason, by shortening the time required to read the charges for one screen by the amount that the charges are not read from the subsequent optical black pixel area, it is possible to shorten the frame shooting cycle and perform higher-speed shooting. Become. In addition, the two-dimensional imaging device itself can be manufactured at low cost because it only involves minor modifications to existing devices.
There is no increase in the price of the entire imaging device.

In a preferred embodiment of the image pickup apparatus according to the present invention, the specific horizontal line band in which the photosensitive pixel area is provided is arranged close to the horizontal shift register.

Regarding the former-stage optical black pixel area sandwiched between the horizontal shift register and the specific horizontal line band (photosensitive pixel area), whether all the lines are put together or how many times every plural lines Even if you divide them, you have to read them all. Therefore, the smaller the total number of lines in the preceding optical black pixel area, the shorter the time required to start effective image reading. In addition, since the specific horizontal line band having a sufficiently small width is arranged close to the horizontal register, the subsequent optical black pixel area in which the charge readout time does not occur occupies most of the total number of horizontal lines. The time required to read out the minute charges is greatly reduced.

In a preferred embodiment of the image pickup apparatus according to the present invention, the preceding-stage optical black pixel region corresponding processing performs an operation of performing continuous vertical transfer of a plurality of stages every one horizontal period over one or more horizontal periods. It includes processing to be performed repeatedly. As a result, unnecessary images obtained from the preceding optical black pixel area can be discharged to the horizontal shift register at high speed.

Further, in a preferred embodiment,
The dropping of charges into the horizontal shift register is performed while the operation of performing a plurality of stages of continuous vertical transfer every horizontal period is stopped while the transfer of the horizontal shift register is stopped during the horizontal period. Thus, the accumulated charges are output in the video signal each time the desired dropping of a plurality of lines is completed, so that image processing based on the video signal is simplified.

In a preferred embodiment of the image pickup apparatus of the present invention, the light-sensitive pixel area corresponding processing includes a continuous vertical transfer operation of one or more stages and a continuous horizontal transfer operation of a stage number corresponding to one horizontal line pixel. Is performed by shifting the time zone back and forth within one horizontal period.
As a result, the electric charges of the same column are superimposed on the required number of stages,
It is possible to obtain a desired effective image at a desired resolution and brightness.

A visual measurement device according to the present invention includes the above-described imaging device, and an image processing device that receives image data output from the imaging device and performs predetermined image processing. is there. This makes it possible to acquire image data at a required resolution at high speed from a long and narrow field of view and perform measurement processing with high response. Sensors, 3D sensors, length measuring sensors, barcode readers, etc.).

Similarly, another image pickup apparatus of the present invention includes a two-dimensional image pickup device having a novel configuration proposed by the present inventors, and a dedicated drive control unit for driving this image pickup device. ing.

The two-dimensional image pickup device collectively collects the light receiving pixel groups arranged in a matrix corresponding to the field of view of a standard image pickup device, the vertical shift registers of each column, and the outputs of the vertical shift registers of each column. A horizontal shift register for receiving the data.

In a specific horizontal line band having a width sufficiently smaller than the total number of horizontal lines on the light receiving surface of the two-dimensional image sensor,
By defining the surrounding area as an optical black pixel area, a photosensitive pixel area is formed.

The basic functions of the drive control unit are to take in signal charges from the light receiving pixels to the vertical shift registers of each column, to vertically transfer signal charges by the vertical shift registers of each column, and to perform signal transfer by the horizontal shift registers. It controls the horizontal transfer of charges.

More specifically, at the beginning of each vertical period, the drive control section includes a signal charge taking-in process for taking in signal charges from the light receiving pixels to the vertical shift registers of each column, and a pre-stage optical black pixel area. The front-stage optical black pixel area corresponding processing to quickly drop the signal charge on the vertical shift register of each column taken into the horizontal shift register from the vertical shift register, and the processing on the vertical shift register of each column taken from the photosensitive pixel area A signal-sensitive pixel area corresponding process for reading out signal charges to the outside by appropriately linking the transfer of the vertical shift register and the transfer of the horizontal shift register of each column to the outside, and the vertical shift of each column taken from the subsequent optical black pixel region Subsequent optical black pixel area processing to quickly drop the signal charge on the register into the horizontal shift register The door, and is configured to repeatedly execute.

According to the imaging apparatus having the above configuration, the light receiving pixel group belonging to the light sensitive pixel area generates an electric charge corresponding to the amount of received light in response to the light image from the elongated object area to be photographed. The light receiving pixels belonging to the first and second optical black pixel regions are insensitive to light images arriving from other than the elongated subject region to be photographed,
Generates no or little charge.

Among the stages of the vertical shift register in each column, the charge corresponding to the amount of received light is transferred and stored in the stage located in the photosensitive pixel area. No or almost no charge is transferred and stored in the stages located in the first and second optical black pixel regions.

When the drive control unit operates, the electric charges in the optical black pixel regions in the preceding and subsequent stages are read out collectively for a plurality of horizontal lines. At this time, the stored charges of the stages belonging to the optical black pixel region at the former stage and the latter stage of the vertical shift register of each column are almost zero. Therefore, in principle, the charge of several lines is added at each stage of the horizontal shift register. Even
There is no risk of charge saturation at any stage of the horizontal shift register. Therefore, while unnecessary charges on horizontal lines are added together and read out as quickly as possible, charges on a specific horizontal line band, which is a photosensitive pixel area, are read out one by one or several lines at a desired accuracy. First, by shortening the time required to read the charges for one screen, it is possible to shorten the frame shooting cycle and perform high-speed shooting.

In a preferred embodiment of the image pickup apparatus according to the present invention, a pre-stage optical black pixel region corresponding process,
And / or the subsequent-stage optical black pixel region corresponding process includes a process of repeatedly performing an operation of performing a plurality of stages of continuous vertical transfer every one horizontal period over one or more horizontal periods. Thereby, the former stage and / or
Alternatively, the unnecessary image obtained from the subsequent optical black pixel area can be discharged to the horizontal shift register at high speed.

Further, in a preferred embodiment,
The dropping of charges into the horizontal shift register is performed while the operation of performing a plurality of stages of continuous vertical transfer every horizontal period is stopped while the transfer of the horizontal shift register is stopped during the horizontal period. Thus, the accumulated charges are output in the video signal each time the desired dropping of a plurality of lines is completed, so that image processing based on the video signal is simplified.

In a preferred embodiment of the image pickup apparatus according to the present invention, the effective image correspondence processing includes a continuous vertical transfer operation of one or more stages and a continuous horizontal transfer operation of a stage corresponding to one horizontal line pixel number. The processing includes shifting the time zone back and forth within one horizontal period. This makes it possible to obtain a desired effective image at a desired resolution while superimposing the electric charges of the same column by the required number of stages.

A visual measurement device according to the present invention includes the above-described imaging device, and an image processing device that inputs image data output from the imaging device and performs predetermined image processing. is there. This makes it possible to acquire image data at a required resolution at high speed from a long and narrow field of view and perform measurement processing with high response. Sensors, 3D sensors, length measuring sensors, barcode readers, etc.).

[0057]

BEST MODE FOR CARRYING OUT THE INVENTION A visual measuring device according to an embodiment of the present invention (for example, a displacement sensor using a light section method,
FIG. 1 is a block diagram showing an electrical hardware configuration of a three-dimensional sensor or the like.

As shown in the figure, a visual measuring device 100 generates an image signal of a two-dimensional image and outputs the image signal, and captures the image signal output from the image capturing device 1 to perform measurement. And an image processing apparatus 2 for executing various image processing.

The image pickup apparatus 1 has a CC as a solid-state image pickup device.
D image sensor 11 (abbreviated as “CCD” in the figure), transfer pulse generator 12, transfer controller 13, output buffer 14
And a transfer specification table 15. The transfer pulse generator 12, the transfer controller 13, and the transfer specification table 15 constitute a drive controller of the present invention.

The image processing device 2 performs image processing for predetermined measurement using the image input unit 21 for A / D converting the video signal from the imaging device 1 and the digital image after the conversion process. It includes an image processing unit 22 and an output unit 23 for outputting the image processing result to the outside.

The CCD image pickup device 11 has a novel configuration proposed by the present inventor. An example of a pixel array on the light receiving surface of the CCD image sensor is schematically shown in FIG. It should be noted that, even in this example, the size of the pixel is considerably exaggerated from the actual size.

In the figure, Ph denotes a vertical direction corresponding to the visual field of a digital still camera which is a standard image pickup device.
Each of the light receiving pixels constituting a light receiving pixel group arranged in a matrix of 88 rows × 1077 columns in the horizontal direction, and VR is a vertical line for vertically transferring the output of each light receiving pixel Ph constituting the light receiving pixel group for each column. The shift register HR receives a charge transferred from the vertical shift register VR in each column and transfers the charge in the horizontal direction.
Out is an output buffer for outputting the charges transferred from the horizontal shift register HR to the outside.

Among the light receiving pixels Ph, the light receiving pixel Ph2 filled with hatching in the figure is a so-called optical black pixel (OB pixel), and the white light receiving pixel Ph1 that is not filled with hatching in the figure is photosensitive. Pixel. Each of the light receiving pixels Ph1 and Ph2 has an element structure based on a photodiode. The vertical and horizontal shift registers VR and HR have an element structure based on a CCD.

As described above, light cannot be received from the optical black pixel Ph2 by the light-shielding mask, no charge is accumulated even when light is received, or the charge accumulated by light reception is not taken out. The output of the pixel is always fixed to a prescribed dark level (corresponding to almost zero charge) regardless of the amount of received light. The photosensitive pixel Ph1 is a normal light receiving pixel that does not employ such a special structure, and its output is a light level corresponding to the amount of received light.

Various methods are conceivable as a method for making the target pixel an optical black pixel Ph2 instead of the photosensitive pixel Ph1. As a first method, a photoelectric conversion element (for example, a photodiode, a phototransistor, or the like) constituting a target light-receiving pixel is used.
Is covered with a light shielding mask. Specifically, in a semiconductor manufacturing process, a light-shielding mask can be realized by forming a metal mask that does not transmit light on a photodiode constituting a light-receiving pixel. Realizing a light-shielding mask also by pasting a light-impermeable mask (for example, aluminum foil) on the light-receiving surface of the device at a stage after the end of the semiconductor manufacturing process (for example, after a product purchase). Can be.

As a second method, in a semiconductor manufacturing process, the element structure itself of a photodiode constituting a target light receiving pixel is modified so that the element cannot receive light or cannot perform photoelectric conversion. No.

A third method is to cut off a charge transfer path from a photodiode constituting a target light receiving pixel to a vertical shift register in a semiconductor manufacturing process.

Even if any of the first to third methods is adopted, a dedicated CCD image pickup device having a small number of horizontal lines (for example, about 60 to 70 lines), which fits into a long and narrow rectangular view for measurement, is first used. Design cost and design time can be greatly reduced compared to the case of redesigning from the beginning. It goes without saying that the first to third methods can be used together.

Returning to FIG. 2, the light receiving pixel group arranged in a matrix has a specific horizontal line band H having a sufficiently small number of lines (60 lines) compared to the total number of horizontal lines (788 lines).
The first pixel group belonging to LB and the specific horizontal line band HLB
And a second pixel group that does not belong to.

That is, in this example, 60 horizontal lines from the eighth horizontal line to the 67th horizontal line from the top of the screen are defined as the specific horizontal line band HLB,
A pixel group included in the specific horizontal line band HLB is a first pixel group. Also, seven horizontal line bands from the top of the screen to the first horizontal line to the seventh horizontal line, and 721 from the 68th horizontal line to the 788th horizontal line at the bottom A pixel group included in the horizontal line band of the book is a second pixel group.

All or most of the pixels Ph constituting the first pixel group are light-sensitive pixels Ph1, and all or most of the pixels Ph constituting the second pixel group (in this example, All) are optical black pixels Ph2.

More specifically, the specific horizontal line band HL
Among the pixels belonging to the 60 horizontal lines constituting B,
Pixels belonging to three vertical lines near the left edge of the screen and pixels belonging to 40 vertical lines near the right edge of the screen are all optical black pixels Ph2. Pixels belonging to 1034 vertical lines positioned at the center between the three vertical lines on the left edge and the 40 vertical lines on the right edge are all light-sensitive pixels Ph1. As a result, the photosensitive pixel area (60 rows × 1034 columns) is surrounded by the optical black pixel area, and the outline of the effective image area is clarified.

FIG. 3 shows the relationship between the size of the photosensitive pixel area and the size of the optical black pixel area in the CCD image sensor in terms of the actual screen aspect ratio. As shown in the figure, it is understood that the photosensitive pixel area (60 rows × 1034 columns) occupies only a part of the entire light receiving surface (788 rows × 1077 columns). It can also be understood that the specific horizontal line band HLB constituting the photosensitive pixel area is arranged close to the top of the screen where the horizontal shift register HR exists. Further, the entire light receiving surface (788 rows × 10
It is also understood that the majority of the (77 columns) are occupied by the optical black pixel area.

The circuit configuration of the CCD image pickup device 11 is the same as that of the conventional device described above with reference to FIG.
It operates by receiving first to third transfer pulses TP1 to TP3 output from a transfer pulse generator 12 described later.

That is, in the CCD image pickup device, when a first transfer pulse TP1 is given from the outside, the output of the pixel Ph belonging to each vertical line (in the case of the photosensitive pixel Ph1, the accumulated charge during the shutter open period, In the case of the black pixel Ph2, almost zero charge corresponding to a prescribed dark level) is transferred to the corresponding stage of the adjacent vertical shift register VR1 to VRn.

When a second transfer pulse TP2 is externally applied, each of the vertical shift registers VR1 to VRn is shifted by one stage, and each of the vertical shift registers VR1 to VRn is shifted.
The charge stored in the first stage of VRn is transferred to the corresponding stage of the horizontal shift register HR.

When a third transfer pulse TP3 is applied from the outside, the horizontal shift register HR is shifted by one stage, and the electric charge stored in the first stage of the horizontal shift register is output to the outside via the output section Aout. Is done.

Next, the configuration of the drive control section of the CCD image sensor described above will be described. This drive control unit is mainly configured by a transfer pulse generation unit 12 and a transfer control unit 13.

The number-of-transfer-lines specifying unit 13 determines the number of lines of image data to be transferred in one horizontal period, and outputs the third transfer pulse TP3 in each horizontal period corresponding to one horizontal line pixel. This is for setting whether to output image data to the outside. The set number of transfer lines is 2
Are converted into bit line transfer line number signals L1 and L2,
The presence / absence of an external output is converted into an output presence / absence signal OE, which is output to the transfer pulse generator 12.

The transfer line number signal L 1 for each transfer line number
FIG. 4 shows a data configuration of L2 and the external output presence / absence signal OE.
(A) and (b) respectively. As shown in the figure, for each of the number of transfer lines 1, 2, 4, and 7,
Codes “00”, “10”, “01”, and “11” are assigned, respectively, and the upper bit of the code is set as L1 and the lower bit is set as L2. Further, the output presence / absence signal OE is determined by TP3
No output is set to "0" and TP3 output is set to "1".

FIG. 5 shows the internal configuration of the generation unit of the first, second, and third transfer pulses TP1, TP2, and TP3 in the transfer pulse generation unit 12. The first transfer pulse generator includes a timing generator 121 which generates and outputs a first transfer pulse TP1 for pixel charge conversion in response to an externally applied vertical period start command XVD.

The second transfer pulse generator has four timing generators 122a, 122b, 122c, 122d.
And a multiplexer 123 for selectively outputting a pulse train from each of the timing generators 122a to 122d.

Each of the timing generators 122a to 122d
Are used for transfer of 1, 2, 4, and 7 lines, respectively, and within a period having the same length as the horizontal period of the normal video standard, the second transfer pulse TP2 corresponding to the number of corresponding transfer lines is used. Is output. Each of the timing generators 122a to 122
The output form of the transfer pulse TP2 from 2d is shown in FIG.

As shown in the figure, the one-line transfer timing generator 122a outputs one pulse during the horizontal blanking period.

Timing generator 122 for two-line transfer
b outputs two pulses during the horizontal blanking period.

Timing generator 122 for 4-line transfer
c outputs two pulses during the horizontal blanking period and two pulses outside the horizontal blanking period.

Timing generator 122 for 7-line transfer
d outputs two pulses during the horizontal blanking period and five pulses outside the horizontal blanking period.

The multiplexer 123 selects a timing generator for the number of transfer lines indicated by the transfer line number signals L1 and L2 from the timing generators 122a to 122d, and changes the input path of the signal to the CCD image pickup device 11. Connect to output path. As a result, the output pulse of the selected timing generator is adopted as the transfer pulse TP2 and is supplied to the CCD image sensor 11.

Although not shown here, the generation unit of the first transfer pulse TP1 is also composed of four timing generation units for each number of transfer lines and a multiplexer, similarly to the above. The one-line transfer timing generator outputs one pulse signal at a timing based on a normal video standard, whereas the two- to seven-line transfer timing generators are determined by the number of transfer lines. One pulse signal is output every output period of one screen charge.
As described above, the multiplexer outputs the transfer line number signal L1,
By selecting the timing generation section corresponding to L2, the output pulse of the timing generation section becomes the transfer pulse T
It is output as P1 and given to the CCD image sensor 11.

The third transfer pulse generator includes a timing generator 124 for generating and outputting a third transfer pulse TP3 corresponding to one line pixel, and a third transfer pulse TP3 in response to the output presence / absence signal OE. , And a gate circuit 125 for controlling whether or not external output is possible. When the output presence / absence signal OE is “1”, the gate 125 opens, and the output presence / absence signal OE is output.
Is "0", the gate 125 is closed.

As described above with reference to FIG. 2, in the CCD image pickup device 11 of this embodiment, 60 lines of 8 to 67 lines on the light receiving surface are photosensitive pixel areas (effective image areas and ) And 7 lines 1 to 7 and 68
720 lines from 788 to 788 are optical black pixel areas (unnecessary image areas) in the first and second stages. In order to realize a visual measurement device with good responsiveness, it is necessary to read out such one-screen image data (signal charge) as quickly as possible without destroying the data of the effective image area. As a high-speed image reading method for that,
Two types are possible.

In the first high-speed image reading method, the drive control section performs a signal charge capturing process for capturing signal charges from the light receiving pixels Ph to the vertical shift registers VR1 to VRn of each column at the beginning of each vertical period. And the signal charges on the vertical shift registers VR1 to VRn of each column taken in from the preceding optical black pixel area are transferred to the horizontal shift register HR.
And the signal charges on the vertical shift registers VR1 to VRn of each column captured from the photosensitive pixel region are transferred to the vertical shift registers VR1 to VRn of each column and horizontally. The transfer of the shift register HR is appropriately linked to the light-sensitive pixel area corresponding processing for reading out to the outside, and the signal charges on the vertical shift registers VR1 to VRn of each column taken in from the subsequent optical black pixel area are horizontally transferred. The second-stage optical black pixel region corresponding process to be dropped into the shift register HR is configured to be repeated without being interposed therebetween, thereby shortening the one-screen read cycle by the amount that the second-stage optical black pixel region corresponding process is not performed. .

In the second high-speed image reading method, the drive control section performs a signal charge capturing process for capturing signal charges from the light receiving pixels to the vertical shift registers VR1 to VRn of each column at the beginning of each vertical period. , Vertical shift register VR of each column fetched from the preceding optical black pixel area
The first-stage optical black pixel area corresponding processing for rapidly dropping the signal charges on the horizontal shift register HR into the horizontal shift registers HR, and the signal charges on the vertical shift registers VR1 to VRn of each column taken in from the photosensitive pixel area. The transfer of the vertical shift registers VR1 to VRn of each column and the transfer of the horizontal shift register HR are appropriately connected to each other to read out the light-sensitive pixel region, and the vertical shift of each column taken from the subsequent optical black pixel region. The signal charges on the shift registers VR1 to VRn are transferred to the horizontal shift register HR.
And a subsequent stage optical black pixel region corresponding process for causing the vertical shift registers VR1 to VR1 of the respective columns taken in from the preceding stage and the subsequent stage optical black pixel regions. The signal charge on VRn is transferred to the horizontal shift register H
The one-screen reading cycle is shortened by the amount that is dropped into R at high speed.

A specific example of the first high-speed image reading method will be described with reference to FIGS. In this example,
The drive control unit (constituted by the transfer pulse generation unit 12 and the transfer control unit 13) includes a signal charge capture process (A), a pre-stage optical black pixel process (B), and a photosensitive pixel region process (C). Are repeated without interposing the post-stage optical black pixel region correspondence processing (D).

Here, the signal charge taking-in process (A) is a process of taking in signal charges from the light receiving pixels Ph (m, n) to the vertical shift registers VR1 to VRn of each column at the beginning of each vertical period. It is.

The preceding-stage optical black pixel corresponding processing (B) means that the signal charges on the vertical shift registers VR1 to VRn of each column taken from the preceding-stage optical black pixel region (1 to 7 lines) are converted into horizontal shift registers HR. This is the process of dropping

The photosensitive pixel area correspondence processing (C) means that the signal charges on the vertical shift registers VR1 to VRn of each column taken from the photosensitive pixel area (8 to 67 lines) are read out of each column. This is a light-sensitive pixel area corresponding process in which the transfer of the shift registers VR1 to VRn and the transfer of the horizontal shift register HR are appropriately linked to be read out to the outside.

Further, the post-stage optical pixel region correspondence processing (D) is a process of the post-stage optical black pixel region (6).
This is post-processing in which signal charges on the vertical shift registers VR1 to VRn of each column taken in from 8 to 788 lines) are dropped into the horizontal shift register HR.

The preceding-stage optical black pixel area correspondence processing (B) in this example includes an operation of performing seven-stage continuous vertical transfer every one horizontal period. The operation of performing the seven-stage continuous vertical transfer for each horizontal period is performed until the transfer of the horizontal shift register is stopped during the horizontal period (see FIGS. 9 and 10).

In this example, the light-sensitive pixel area correspondence processing (C) includes a two-stage continuous vertical transfer operation and a continuous horizontal transfer operation of the number of stages corresponding to one horizontal line pixel in a time zone within one horizontal period. Is shifted back and forth. As will be described later, in this example, the two-stage continuous vertical transfer operation is performed during the horizontal blanking period (see FIGS. 9 and 1).
1).

FIG. 7 shows a setting example of the transfer specification table 15 used in the first high-speed image reading method. As shown in FIG.
, The number of transfer lines and the set value of the presence / absence of output in each horizontal period are stored in the form of transfer line number signals L1 and L2 in association with the horizontal period counter value indicating the number of horizontal periods. ing.

In this example, a video signal corresponding to the preceding optical black pixel region is transferred continuously for seven lines in one horizontal period, and a video signal corresponding to the following photosensitive pixel region is transferred to one line.
This is an example in which two lines are transferred every horizontal period. After setting the number of transfer lines in the first one horizontal period to seven, the transfer lines in the second to 31st horizontal periods are changed to two lines. You have set. Regarding the presence / absence of the output by the horizontal transfer, the presence / absence of the output in the first one horizontal period is “absent”, and the presence / absence of the output in the second to 31st horizontal periods is “present”.

Returning to FIG. 1, the transfer control unit 13 reads the set values of the transfer line number signals L1 and L2 and the output presence / absence signal OE stored in the transfer specification table 15 for each horizontal period, and The line number signals L1 and L2 and the output presence / absence signal OE are set to levels according to the set values, and output to the transfer pulse generator 12. Transfer pulse generator 12
Sets the output timing of the first transfer pulse based on the MAX value ("31" in FIG. 7) of the horizontal period counter set in the transfer specification table 15 (that is, 31/788 of the vertical period of the video standard). The transfer pulse TP1 is output at time intervals).

The transfer pulse generator 12 outputs the transfer line number signal L given by the transfer controller 13 for each horizontal period.
The number of outputs of the second transfer pulse TP2 and the presence or absence of the third transfer pulse TP3 are set based on 1, L2 and the output presence / absence signal OE, and a series of controls on the CCD image sensor 11 are performed.

The image processing apparatus 2 is configured to set the number of each transfer line in the transfer specification table 15 and the value of the presence or absence of output from the transfer specification table 15 as necessary.

The outline of the transfer control processing executed in the transfer control unit 13 is shown in the flowchart of FIG.
This transfer control process is started in response to the arrival of the horizontal period start signal HD (see FIG. 9) coming from the transfer pulse generator 12. A series of subsequent operations are periodically repeated based on the value of the horizontal period counter LC incorporated in the transfer control unit 13.

It is now assumed that the horizontal period counter LC has been cleared. In this state, when the horizontal period start signal HD arrives, the processing of FIG. 8 is started, and the value of the horizontal period counter LC is counted up from "0" to "1" (step 801).

When the value of the horizontal period counter LC becomes "1", the transfer specification table 1 is used with the count value "1" as an argument.
5 is referred to, whereby the transfer line number signals L1, L2
The set value of the output presence / absence signal OE is read. FIG.
At this time, the number of transfer lines is "7", and the external output by horizontal transfer is "none" at this time (step 802).

According to the contents of the set values read from the transfer specification table 15, the values of the transfer line number signals L1, L2 and the horizontal transfer presence / absence signal OE are L1 = 1, L2 = 1,
OE = 0 is set (step 803). Then, as shown in FIGS. 9 and 10, in the first horizontal period corresponding to the count value “1”, the second transfer pulse for vertical transfer is not output without outputting the third transfer pulse for horizontal transfer.
The transfer pulse generator 12 has only seven transfer pulses
Output from As a result, although no signal is output in the video signal (empty state), charges of seven lines 1 to 7 are dropped and superimposed on each stage of the horizontal shift register HR. Thereafter, the process ends (NO in step 804), and a state is made to wait for the next horizontal period start signal HD to arrive.

When the second horizontal period start signal HD arrives, the process of FIG. 8 is started, and the value of the horizontal period counter LC is counted up from "1" to "2" (step 801).

When the value of the horizontal period counter LC becomes "2", the transfer specification table 1 is used with the count value "2" as an argument.
5 is referred to, whereby the transfer line number signals L1, L2
The set value of the output presence / absence signal OE is read. FIG.
As is clear from the conversion table, the number of transfer lines is "2" at this time, and the external output by horizontal transfer is "present" (step 802).

In accordance with the contents of the set values read from the transfer specification table 15, the values of the transfer line number signals L1, L2 and the horizontal transfer presence / absence signal OE are L1 = 0, L2 = 1,
OE = 1 is set (step 803). Then, as shown in FIGS. 9 and 11, in the second horizontal period corresponding to the count value “2”, the transfer pulse generation unit 12 outputs the second transfer pulse TP2 for vertical transfer.
Are output during the horizontal blanking period, and after the end of the horizontal blanking period, third transfer pulses TP3 for horizontal transfer are output by the number corresponding to one horizontal line pixel.

When two second transfer pulses TP2 are output during the horizontal blanking period, the horizontal shift register HR
In addition, two lines of 8, 9 lines are further dropped on the electric charges of 7 lines of 1 to 7 lines accumulated in each stage, and the electric charges of 9 lines of 1 to 9 lines as a whole are dropped. Are superimposed. Thereafter, when the third transfer pulse TP3 for horizontal transfer is output by the number corresponding to one horizontal line pixel, the above-described superimposed charges for nine lines are output in the video signal. As shown by hatching in FIG. 9 and surrounded by a dotted line in FIG. 11, the video signal portion on which the charges for the nine lines are superimposed becomes an OB unnecessary video signal. As a result, the first two lines in the video signal are invalid image portions. Thereafter, the process ends (step 804 NO),
It is in a state of waiting for the arrival of the next horizontal period start signal HD.

When the third horizontal period start signal HD arrives, the process of FIG. 8 is started, and the value of the horizontal period counter LC is counted up from "2" to "3" (step 801).

When the value of the horizontal period counter LC becomes "3", the transfer specification table 1 is used with the count value "3" as an argument.
5 is referred to, whereby the transfer line number signals L1, L2
The set value of the output presence / absence signal OE is read. FIG.
As is clear from the conversion table, the number of transfer lines is also "2" at this time, and the external output by horizontal transfer is determined to be "present" (step 802).

According to the contents of the set values read from the transfer specification table 15, the values of the transfer line number signals L1, L2 and the horizontal transfer presence / absence signal OE are L1 = 0, L2 = 1,
OE = 1 is set (step 803). Then, as shown in FIG. 9 and FIG. 11, in the third horizontal period corresponding to the count value “3”, the transfer pulse generator 12 outputs the second transfer pulse TP2 for vertical transfer.
Are output during the horizontal blanking period, and after the end of the horizontal blanking period, third transfer pulses TP3 for horizontal transfer are output by the number corresponding to one horizontal line pixel.

When two second transfer pulses TP2 are output during the horizontal blanking period, the horizontal shift register HR
In each of the stages in the empty state, the electric charges of two lines of 10, 11 lines are dropped and superimposed. At this time, the charge on each stage of the horizontal shift register HR is:
Although the two lines are superimposed, the features of the original image still remain sufficiently. Thereafter, when the third transfer pulse TP3 for horizontal transfer is output by the number corresponding to one horizontal line pixel, the above-mentioned superposed charges for two lines are output in the video signal. As shown in FIGS. 9 and 11,
The video signal portion on which the charges for the two lines 10 to 11 are superimposed becomes an effective video signal.

Thereafter, the operation when the fourth to 31st horizontal period start signals HD arrive is the same as the operation when the third vertical period start signal HD arrives. Therefore, when the fourth to 31st vertical period start signals HD arrive, as shown in FIG. 9 and FIG.
Video signals in which two lines of 13 lines, 14, 15 lines, and 66 to 67 lines are superimposed are sequentially output.

When the 31st horizontal period start signal arrives, the value of the line counter LC reaches the maximum value (step 804 YES), and a vertical period start command XVD is output (step 805). The content is cleared to "0" (step 806). In response to the vertical period start command XVD, the transfer pulse generator 1
2 outputs a first transfer pulse TP1 for taking in pixel charges. Thereafter, the signal charges of lines 68 to 788 are left on the vertical shift registers VR1 to VRn while the first to 31st horizontal lines described above are left. The processing when the period start signal arrives is repeated.

When the transfer pulse TP1 for capturing the second and subsequent pixel charges is output, the signal charges are again supplied from the light receiving pixels Ph (m, n) to the vertical shift registers VR1 to VRn in each column. It is captured. At this time, electric charges transferred from the subsequent optical black pixel region should exist in each stage of the vertical shift registers VR1 to VRn located in the photosensitive pixel region. However, since the charge from the subsequent optical black pixel region is very small or equal to zero, even if the effective image charge is taken in and superimposed thereon, the effective image is deteriorated due to the so-called double removal phenomenon. There is no fear. That is, even if the charge is overwritten on the charge from the subsequent optical black pixel region, the double take-off phenomenon does not occur.

Therefore, according to the first high-speed image reading method, it is possible to proceed to the next photographing while leaving the signal charges of 68 to 788 lines on the vertical shift registers VR1 to VRn. By increasing the number of frames to be shot, so-called high-speed shooting becomes possible.

FIG. 12 is a table showing image data for one screen obtained by adopting the first high-speed image reading method. As shown in the drawing, two lines of 1-2 lines are regarded as invalid images, and 29 lines of 3-31 lines are regarded as valid images.

When the image data generated in this manner is taken into the image processing apparatus 2, the image processing section 22 applies, for example, a binarization process to the image data in the effective image area.
After extracting an object on the image by using a method such as an edge extraction process, feature amounts such as an area and a position of a center of gravity of the extracted object are measured. It should be noted that the specific contents of the feature amount measurement processing are as follows.
It is determined depending on which of the D sensor, the length measuring sensor, the bar code reader, and the like corresponds.

At this time, since the image data for one screen is taken in about 1/25 of the normal time, the time required for image input is greatly reduced, and the processing efficiency is improved. In addition, since the charges are not saturated on the horizontal shift register HR, there is no possibility that the image in the effective image area is deteriorated due to the occurrence of smear due to the saturation. In addition, for an effective image area that requires detailed processing, image data having the same resolution as image data generated by a normal video standard can be obtained, so that the accuracy of the measurement processing can be maintained.

Thereafter, if necessary, the result of the measurement is compared with a preset reference value to judge the quality of the object. The measurement result and the determination result are output to an external device such as a monitor via the output unit 23.

Next, a specific example of the second high-speed image reading method will be described with reference to FIGS. In this example, the drive control unit (including the transfer pulse generation unit 12 and the transfer control unit 13) performs the signal charge capturing process (A).
And the preceding optical black pixel region corresponding process (B), the photosensitive pixel region corresponding process (C), and the subsequent optical black pixel region corresponding process (D) are configured to be repeatedly executed. The one-screen read cycle is shortened by the amount that the signal charges on the vertical shift registers VR1 to VRn of each column taken in from the subsequent optical black pixel areas (B) and (D) are quickly dropped into the horizontal shift register HR. I do.

Here, the signal charge taking-in process (A) is a process of taking in signal charges from the light receiving pixels Ph (m, n) to the vertical shift registers VR1 to VRn of each column at the beginning of each vertical period. It is.

The preceding-stage optical black pixel area corresponding processing (B) means the vertical shift registers VR1 to VRn of each column taken in from the preceding-stage optical black pixel area.
This is a process of dropping the upper signal charge into the horizontal shift register HR at a high speed.

The photosensitive pixel area corresponding processing (C) is to transfer the signal charges on the vertical shift registers VR1 to VRn of each column taken from the photosensitive pixel area to the vertical shift registers VR1 to VRn of each column. This is a process of reading out to the outside by linking the transfer of the horizontal shift register HR appropriately.

The post-stage optical black pixel region correspondence processing (D) means the vertical shift registers VR1 to VRn of each column taken in from the post-stage optical black pixel region.
This is a process of dropping the upper signal charge into the horizontal shift register HR at a high speed.

The first-stage optical black pixel region corresponding process (B) and / or the second-stage optical black pixel region corresponding process (D), in this example, perform an operation of performing seven-stage continuous vertical transfer every one horizontal period. It includes processing to be performed repeatedly over one or more horizontal periods. The operation of performing the seven-stage continuous vertical transfer for each horizontal period is performed until the transfer of the horizontal shift register HR is stopped during the horizontal period (see FIG. 14).

In the light-sensitive image area correspondence processing (C), the time zone is shifted forward and backward within one horizontal period between the continuous vertical transfer operation of two stages and the continuous horizontal transfer operation of the number of stages corresponding to one horizontal line pixel. (See FIG. 14).

FIG. 13 shows a setting example of the transfer specification table 15 used in the second high-speed image reading method. As shown in FIG.
, The number of transfer lines and the set value of the presence / absence of output in each horizontal period are stored in the form of transfer line number signals L1 and L2 in association with the horizontal period counter value indicating the number of horizontal periods. ing.

In this example, a video signal corresponding to the preceding optical black pixel area is transferred continuously for seven lines in one horizontal period, and a video signal corresponding to the subsequent photosensitive pixel area is converted to one.
In this example, two lines are set to be transferred every horizontal period, and the subsequent optical black pixel area is transferred seven lines continuously in one horizontal period. The number of transfer lines in the first horizontal period is set to seven. After setting the line,
The transfer lines in the second horizontal period are set to two lines, and the transfer lines in the 32nd to 134th horizontal periods are set to seven lines. Regarding the presence / absence of output by horizontal transfer, the presence / absence of output in the first one horizontal period is “absent”, then the presence / absence of output in the second to 31st horizontal periods is “present”, and thereafter, 32 to 134
The presence / absence of output in the second horizontal period is set to “none” again.

The transfer control processing executed by the transfer control unit 13 is basically the same as that shown in the flowchart of FIG. Therefore, the second high-speed image reading method will be described with reference to the flowchart again.

The count value “1” of the horizontal period counter LC
Operations up to "31" are the same as those in the first high-speed image reading process. That is, in the horizontal period corresponding to the count values “1” and “2” (mainly, the preceding optical black pixel area), the charge of seven lines of 1 to 7 lines accumulated in each stage of the horizontal shift register HR is increased. Further, charges for two lines of 8, 9 lines are dropped, and charges for nine lines of 1 to 9 lines are superimposed as a whole, and are output in the vertical period of the count value "2" in the video signal. You. The video signal portion on which the charges for nine lines are superimposed becomes an OB unnecessary video signal, and as a result, the first two lines in the video signal become an invalid image portion (FIG. 14).
Count values "1" and "2").

3 corresponding to the count values “3” to “31”
In the 3rd to 31st horizontal periods (mainly the photosensitive pixel area), lines 10, 11, 12, 13, 1
Video signals on which two lines of 4, 15 lines and ~ 66, 67 lines are superimposed are sequentially output. The video signal portion on which these two lines of charges are superimposed becomes an effective video signal (see count values “3” to “31” in FIG. 14).

In the 32nd to 134th horizontal periods corresponding to the count values “32” to “134” (mainly, the latter-stage optical black pixel area), the transfer pulse generating unit 12 outputs a vertical transfer signal every horizontal period. Although two second transfer pulses TP2 are output during the horizontal blanking period, even when the horizontal blanking period ends, the third transfer pulse TP3 for horizontal transfer is not output, and as a result, the video signal Nothing is output inside (see the count values “32” to “134” in FIG. 14).

FIG. 15 is a table showing image data for one screen obtained by adopting the second high-speed image reading method. As shown in the figure, two lines of 1 to 2 lines are regarded as a preceding invalid image, 29 lines of 3 to 31 lines are regarded as valid images, and 103 lines of 32 to 134 lines are regarded as a succeeding invalid image. Is done.

When the image data generated in this way is taken into the image processing device 2, the image processing section 22 applies, for example, a binarization process to the image data in the effective image area.
After extracting an object on the image by using a method such as an edge extraction process, feature amounts such as an area and a position of a center of gravity of the extracted object are measured.

At this time, since the image data for one screen is captured in about one-fifth of the normal time, the time required for image input is greatly reduced, and the processing efficiency is improved. Moreover,
Even if a large number of electric charges from the optical black pixels are added, the electric charge does not saturate on the horizontal shift register HR, and therefore, there is no possibility that the smear due to the saturation will deteriorate the image in the effective image area. In addition, for an effective image area that requires detailed processing, image data having the same resolution as image data generated by a normal video standard can be obtained, so that the accuracy of the measurement processing can be maintained.

Thereafter, if necessary, the result of this measurement is compared with a preset reference value to determine the quality of the object. The measurement result and the determination result are output to an external device such as a monitor via the output unit 23.

A pixel array serving as a base of the CCD image pickup device 11 constituting the above-described image pickup apparatus 1 is a popular CCD corresponding to a screen aspect ratio of a standard digital still camera.
The pixel array of the image sensor can be used as it is.
Therefore, there is no need to newly design a special pixel array, so that the development cost or development period can be reduced and the cost can be reduced.

[0144] Preferable applications of the above-described imaging apparatus include displacement sensors, 3D sensors, length measurement sensors, bar code readers, and the like based on the light cutting method as a detection principle. The field of view required for these sensors is slender and requires a high resolution in the longitudinal direction. On the other hand, if there is a certain degree of resolution in the direction orthogonal to this, it is possible to check the raw image of the measurement state and the measurement light shape etc. Can also. In the above-described CCD imaging device, a resolution of 1034 pixels can be obtained in the long side direction necessary for displacement measurement, and a maximum resolution of 60 pixels can be obtained in the short side direction.

FIG. 16 schematically shows an application example in which the image pickup apparatus of the present invention is used for a displacement sensor based on a light-section method as a detection principle. FIG. 2A is a schematic perspective view of the displacement sensor head, and FIG. 2B is a schematic sectional view of the displacement sensor head.

In the figure, reference numeral 3 denotes an object to be measured, 4 denotes a line beam for measurement (a beam having a cross-sectional line shape), 5 denotes reflected light, 6 denotes a lens system, 7 denotes a two-dimensional image sensor, and 8 denotes a two-dimensional image sensor. Is a horizontal scanning direction, 9 is a vertical scanning direction of the two-dimensional image sensor, and 10 is a specific horizontal line band on the light receiving surface of the two-dimensional image sensor. In this example, a line beam having a line width of 0.1 × 5 mm is used as the line beam 4. The height displacement of the measurement target 3 is determined by the two-dimensional imaging device 9.
, In the horizontal scanning direction. The elongated field of view comprised of the particular horizontal line band 10 is oriented in a direction along this displacement. Further, in the width direction of the elongated visual field, the width direction distribution of the height displacement appears with a certain resolution, so that the position of the measuring point can be adjusted by visually recognizing the optical image of the line beam and the raw image of the measuring object 3. Becomes easier.

[0147]

As is apparent from the above description, according to the imaging apparatus of the present invention, a long and narrow field of view can be photographed at high speed without deteriorating the image quality, and can be manufactured at low cost. . Therefore, according to the present invention, a visual measurement device (for example, an optical A displacement sensor, a 3D sensor, a length measuring sensor, a bar code reader, etc., which are applicable to the cutting method.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a visual measurement device to which the present invention has been applied.

FIG. 2 is a diagram schematically showing a pixel array on a light receiving surface of a device used in the imaging apparatus of the present invention.

FIG. 3 is a diagram showing a relationship between a photosensitive pixel area and an optical black pixel area in an element used in the image pickup apparatus of the present invention in an actual screen aspect ratio.

FIG. 4 is a diagram showing semantic contents of L1, L2, and OE.

FIG. 5 is a diagram showing an internal configuration of a transfer pulse generator.

FIG. 6 is a time chart showing an output mode of a horizontal transfer pulse (TP2).

FIG. 7 is a diagram illustrating a configuration of a transfer specification table (first high-speed image reading method).

FIG. 8 is a flowchart illustrating an operation of a transfer control unit.

FIG. 9 is a time chart (first high-speed image reading method) illustrating an example of driving the image sensor.

FIG. 10 is a diagram showing a main part of the time chart of FIG. 9;

FIG. 11 is a diagram showing a main part of the time chart of FIG. 9;

FIG. 12 is a diagram (first high-speed image reading method) showing a data configuration of one screen in one driving example of the element of the present invention.

FIG. 13 is a diagram illustrating a configuration of a transfer specification table (second high-speed image reading method).

FIG. 14 is a time chart (second high-speed image reading method) illustrating one driving example of an image sensor.

FIG. 15 is a diagram (second high-speed image reading method) showing a data configuration of one screen in one driving example of the element of the present invention.

FIG. 16 is a diagram illustrating an application example of the imaging apparatus of the present invention.

FIG. 17 is a diagram schematically showing a pixel array on a light receiving surface in a conventional element.

FIG. 18 is a diagram showing the relationship between a photosensitive pixel area and an optical black pixel area in a conventional device in an actual screen aspect ratio.

FIG. 19 is a block diagram for explaining a charge transfer operation in a conventional device.

FIG. 20 is a time chart of a video signal obtained from a conventional imaging device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 imaging device 2 image processing device 3 object to be measured 4 line beam for measurement (beam in cross section line) 5 reflected light 6 lens system 7 two-dimensional image sensor 8 horizontal scanning direction of two-dimensional image sensor 9 of two-dimensional image sensor Vertical scanning direction 10 Specific horizontal line band on the light receiving surface of two-dimensional image sensor 11 CCD image sensor 12 Transfer pulse generator 13 Transfer controller 14 Output buffer 15 Transfer specification table 21 Image input unit 22 Image processing unit 23 Output unit 100 Visual Measuring device 121 Timing generator for taking in pixel charges 122a Timing generator for one-line vertical transfer 122b Timing generator for two-line vertical transfer 122c Timing generator for four-line vertical transfer 122d Timing for seven-line vertical transfer Generator 123 Multiplexer 124 Horizontal transfer Timing signal generating unit 125 gate circuits L1, L2 transfer pulse TP3 transfer pulse for horizontal transfer for the transfer pulse TP2 vertical transfer for the transfer line number signal TP1 charges taking

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/18 H04N 7/18 CF term (Reference) 2F065 AA03 BB11 DD06 FF04 JJ26 QQ31 RR05 5B072 AA01 CC24 LL19 5C022 AA01 AA13 AA14 AB64 AC42 AC54 AC69 5C024 AX01 BX00 BX01 CX13 DX01 EX42 GY01 GZ36 HX02 HX18 HX23 HX28 HX29 HX31 JX21 JX35 5C054 CC00 EA01 EH00 FC05 FC14 FC15 FD00 HA05

Claims (13)

[Claims] 1. A light receiving pixel group arranged in a matrix corresponding to a field of view of a standard image pickup apparatus, a vertical shift register of each column, and a horizontal shift which collectively receives outputs of the vertical shift registers of each column. A two-dimensional image pickup element having a register and forming an optical black pixel area in a specific horizontal line band having a width sufficiently smaller than the total number of horizontal lines by making the periphery an optical black pixel area; A drive control unit that controls the incorporation of the signal charge into the vertical shift register of each column, the vertical transfer of the signal charge by the vertical shift register of each column, and the horizontal transfer of the signal charge by the horizontal shift register; At the beginning of each vertical period, the drive control unit performs a signal charge capturing process for capturing signal charges from the light receiving pixels to the vertical shift registers of each column; A preceding optical black pixel area processing for dropping the signal charges on the vertical shift register of each column taken from the cul black pixel area into the horizontal shift register, and a vertical shift register of each column taken from the photosensitive pixel area The signal charge above is read from the subsequent optical black pixel area, and the light sensitive pixel area corresponding processing for reading out the signal charge to the outside by appropriately linking the transfer of the vertical shift register and the transfer of the horizontal shift register of each column is read out. It is configured to repeat the post-stage optical black pixel region corresponding process of dropping the signal charges on the vertical shift register of each column into the horizontal shift register without intervening, thereby achieving the post-stage optical black pixel region corresponding process. An image pickup apparatus that shortens the one-screen readout cycle by not performing the operation. 2. The image pickup apparatus according to claim 1, wherein the specific horizontal line band uses a two-dimensional image pickup element arranged close to the horizontal shift register. 3. The pre-stage optical black pixel region corresponding process includes a process of repeatedly performing an operation of performing a plurality of stages of continuous vertical transfer every one horizontal period over one or more horizontal periods. Or the imaging device according to 2. 4. The imaging apparatus according to claim 3, wherein the operation of performing continuous vertical transfer of a plurality of stages for each horizontal period is performed while the transfer of the horizontal shift register is stopped during the horizontal period. 5. The light-sensitive pixel area corresponding processing includes a continuous vertical transfer operation of one or two or more stages and a continuous horizontal transfer operation of a number of stages corresponding to one horizontal line pixel in a time zone within one horizontal period. Including processing to be shifted back and forth,
The imaging device according to claim 1. 6. An image pickup apparatus according to claim 1, further comprising: an image processing apparatus that inputs image data output from the image pickup apparatus and performs predetermined image processing. Visual measurement device. 7. The visual measuring device according to claim 6, wherein the visual measuring device is a visual measuring device requiring an elongated visual field, such as a displacement sensor, a three-dimensional sensor, a length measuring sensor, a bar code reader, or the like to which a light section method is applied. Visual measurement device. 8. A horizontal shift which collectively receives a group of light-receiving pixels arranged in a matrix corresponding to a field of view of a standard imaging device, a vertical shift register of each column, and outputs of the vertical shift registers of each column. A two-dimensional image pickup element having a register and forming an optical black pixel area in a specific horizontal line band having a width sufficiently smaller than the total number of horizontal lines by making the periphery an optical black pixel area; A drive control unit that controls the incorporation of the signal charge into the vertical shift register of each column, the vertical transfer of the signal charge by the vertical shift register of each column, and the horizontal transfer of the signal charge by the horizontal shift register; At the beginning of each vertical period, the drive control unit performs a signal charge capturing process for capturing signal charges from the light receiving pixels to the vertical shift registers of each column; The first-stage optical black pixel area corresponding processing to quickly drop the signal charges on the vertical shift register of each column taken from the cul black pixel area into the horizontal shift register, and the vertical processing of each column taken from the photosensitive pixel area The signal charge on the shift register is read out to the outside by appropriately linking the transfer of the vertical shift register and the transfer of the horizontal shift register of each column to the outside. The optical black pixel region corresponding processing at the subsequent stage, in which the signal charges on the vertical shift register of the column are dropped into the horizontal shift register at high speed, is repeatedly executed. The signal charge on the vertical shift register of each column taken from the area The flat shift register by an amount which dropped into the high-speed, shortening the one screen read cycle, the imaging apparatus. 9. The first-stage optical black pixel region corresponding process and / or the second-stage optical black pixel region corresponding process include performing a plurality of stages of continuous vertical transfer every one horizontal period in one or more horizontal periods. The imaging device according to claim 8, further comprising a process for repeatedly performing the operation. 10. The imaging apparatus according to claim 9, wherein the operation of performing continuous vertical transfer of a plurality of stages for each horizontal period is performed while the transfer of the horizontal shift register is stopped during the horizontal period. 11. The effective image correspondence processing includes a continuous vertical transfer operation of one or two or more stages and a continuous horizontal transfer operation of a number of stages corresponding to one horizontal line pixel before and after a time zone within one horizontal period. The imaging device according to claim 8, further comprising a process of performing a shift. 12. An image processing apparatus according to claim 8, further comprising: an image processing apparatus that inputs image data output from the image processing apparatus and performs predetermined image processing. Visual measurement device. 13. The visual measuring device according to claim 12, wherein the visual measuring device is a visual measuring device requiring an elongated visual field, such as a displacement sensor, a three-dimensional sensor, a length measuring sensor, a bar code reader, or the like to which the light section method is applied. Visual measurement device.