JP2905296B2 - CCD video imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-shutter type CCD video imaging apparatus suitable for obtaining an image for analyzing a visualized flow state of a flow field.

[0002]

2. Description of the Related Art There is known a method of visualizing a flow field by injecting a tracer into a fluid in order to know a flow velocity distribution of a flow field created by, for example, a flow of a fluid in a passage. In order to obtain the flow velocity information in the flow field visualized in this way as quantitative data, the state of the visualized flow field is converted into a video signal using an interlaced television camera, and thus obtained. For each image data, two frame images are created from each field image in the frame image, and the trace image formed by the same tracer in each image is converted to a thin line obtained by the thinning process. A method has been proposed in which the distribution of the flow velocity is estimated from the amount of movement between two frame images of the trajectory image formed by the same tracer, which is estimated from the information of the inclination angle and the length (flow visualization, Vol. 9, No. 34, pp. 379-382). Since this method deals with only one frame of television image, it has a feature that the applicable range is wider than that of a method of dealing with two or more frames of television image. However, in the above-described conventional method, a tracking process is performed in which the inclination angle and the length are obtained from the result of the thinning processing of the trail image, and the trail image is estimated using the result. If they are superimposed, there is a problem that the tracking processing result is greatly affected by noise and causes a large error in the flow velocity measurement result. To reduce this error,
In order to visualize the flow, good lighting conditions are an essential requirement, and the particle size of the tracer particles must be selected and used within a certain range. This is because the lengths of the fine lines of the trace images of particles having different particle diameters after the thinning process are different even if the lengths of the trace images are equal. Therefore, there is a problem that these points must be overcome in order to put the above-mentioned conventional technology into practical use.

[0003]

Accordingly, as a flow velocity measuring system capable of reducing the influence of noise and measuring the flow velocity distribution state more accurately, an interlaced scanning image pickup tube without a shutter is used for a visualized flow field. By using a television camera of a system, a logical product operation of each field image data constituting one frame of a television image signal obtained by the above operation is performed to determine a correspondence relationship of a trail image between each field image data. A configuration to determine is proposed. However, in the proposed system, the measurement time is restricted by the NTSC television image sampling cycle. In the case of a vidicon television camera, when the moving speed of the particles in the angle of view is fast, the particle flow Due to the fact that an error occurs in the image length, there is a problem that measurement is difficult in the case of a fast flow.
Accordingly, an object of the present invention is to provide a CCD video image pickup apparatus capable of easily taking an image of a flow field required for measuring a flow velocity or the like regardless of the flow velocity of the flow field. It is in.

[0004]

SUMMARY OF THE INVENTION To achieve the above object, a feature of the present invention is to obtain a two-dimensional flow velocity information of a flow field visualized by injecting a tracer. In a CCD video imaging device for obtaining a signal, a plurality of field-image signals including a plurality of light-to-electric conversion elements arranged in an array can be taken out , and one frame can be obtained by two field image signals.
The constituting a CCD solid-state imaging device so as to constitute a video image signal over beam, the video image signal of one frame
One field image signal is generated by a corresponding vertical synchronization signal.
Exposure start timing delayed by a predetermined time from the timing
Exposure set when the first time elapses
Exposure is performed until the timing and the CCD solid-state imaging device
First shutter control means for taking out the first frame;
A second field image signal constituting the video image signal of the
From the corresponding vertical synchronization signal generation timing.
From the exposure start timing delayed by a fixed time, the first
Set when a second time that is longer than the time elapses
Exposure is performed until the exposure end timing and the CCD solid-state imaging
And a second shutter control unit for taking out from the element .

[0005]

In order to construct a video image signal of one frame ,
When the two field image signals are extracted by the first and second shutter control means as described above , the first field
Image of the visualized flow in the image signal
Of the visualized flow in the field image signal of
An image is when these are combined as a one-frame image
Although there is an overlap, the difference between the two exposure times, that is,
According to the exposure time difference corresponding to the difference between the first time and the second time.
There is a portion where the flow images do not overlap by the amount of the overlap. did
Accordingly, this allows the image in the first field image signal to be displayed.
Correspondence between the image and the signal in the second field image and
In addition, the moving direction of each image can be easily grasped.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a fluid 2 visualized by injecting appropriate white tracer particles 3 such as nylon 12 particles into a fluid 2 in a water tank 1 made of transparent glass.
1 schematically shows a configuration of a flow velocity measuring device 10 for measuring a state of a flow field.

The flow velocity measuring device 10 extracts the image information indicating the temporal change of the position of the tracer particle 3 for indicating the visualized flow state of the flow field. have.

As shown in detail in FIG. 2, the CCD video image pickup device 12 includes a CCD solid-state image pickup device 20 including a large number of light-to-electric conversion elements arranged in a line and capable of extracting a plurality of field image signals. I have it. CCD
A light image of a required flow field is formed on an exposure surface 22 of the solid-state imaging device 20 by an optical system 24.

[0010] 1 corresponding to the image of the imaged flow field
The image data of the frame is replaced with the odd field image data V
The CCD solid-state imaging device 20 is divided into an odd-numbered field portion A and an even-numbered field portion B in order to separate the data into A and even-numbered field image data VB from the CCD solid-state imaging device 20.

A first control section 24 and a second control section 26 are provided for controlling shutter timing for extracting image data from the odd field section A and the even field section B of the CCD solid-state imaging device 20, respectively. The first and second controllers 24 and 26 include a vertical synchronization signal generator 28.
And a vertical synchronizing signal VS composed of a pulse signal output at 1/60 second intervals from the first and second shutter control signals S1 and S2 for shutter control based on the vertical synchronizing signal VS. The signals are output from the first and second control units 24 and 26, respectively. Here, the first shutter control signal S1 and
Is the voltage of the odd field portion A of the CCD solid-state imaging device 20.
Signal for controlling accumulation of load, second shutter control signal
S2 is an even field portion of the CCD solid-state imaging device 20
B is a signal for controlling the accumulation of the electric charge of B
Charge is stored in the CCD solid-state imaging device 20 only while the
Will be multiplied.

FIG. 3 shows first and second control units 24 and 26.
Is shown in detail. In FIG. 3, reference numeral 40 denotes a first setting circuit for setting the shutter opening time TA of the odd-numbered field portion A, and reference numeral 42 denotes a period from generation of a pulse signal of the vertical synchronizing signal VS provided as a trigger signal to start of a shutter opening operation. This is a first delay setting circuit for setting a delay time DA.

The first setting signal M1 indicating the shutter opening time TA set by the first setting circuit 40 and the first delay setting signal N1 indicating the delay time DA set by the first delay setting circuit 42 are vertically synchronized. The signal VS is input to the first timing signal generation circuit 44 to which the signal
D First timing signal T1 indicating the timing at which the shutter of the odd field portion A of the solid-state imaging device 20 should be opened.
Is output from the first timing signal generation circuit 44.

The first timing signal T1 is inputted to a first control circuit 46 which receives a release signal R1 from the outside, and based on each input signal, the CCD solid-state image pickup device 20
The first control circuit 46 outputs a first shutter control signal S1 which becomes a high level at a timing when the shutter of the odd field portion A is opened.

Next, the structure of the second control unit 26 will be described.
Is a second delay setting circuit for setting a delay time DB from the generation of a pulse signal of the vertical synchronization signal VS given as a trigger signal to the start of the shutter opening operation. .

The second setting signal M2 indicating the shutter opening time TB set by the second setting circuit 50 and the second delay setting signal N2 indicating the delay time DB set by the second delay setting circuit 52 are vertically synchronized. The signal VS is inputted to the second timing signal generating circuit 54 to which the signal VS is inputted,
D The second timing signal T2 indicating the timing at which the shutter of the even field portion B of the solid-state imaging device 20 should be opened.
Is output from the second timing signal generation circuit 54.

The second timing signal T2 is inputted to a second control circuit 56 which receives a release signal R2 from the outside, and based on each input signal, the CCD solid-state image pickup device 20
A second shutter control signal S2 which becomes high level at the timing when the shutter of the even-numbered field portion B is opened is output from the first control circuit 56.

FIG. 4 shows the first and second timing signals T
1 and T2 are shown together with the waveform of the vertical synchronization signal VS. In this embodiment, DA and DB are set equal, and TA is set shorter than TB. Therefore, although the rising timings of the first and second timing signals T1 and T2 are simultaneous, the first timing signal T1
Falls, the level of the second timing signal T2 falls.

As described above, the first and second timing signals T1 and T2 are both controlled so as to open the shutter when they are in the high level state. The shutter opening timing of the field portion A is different from the shutter opening timing of the even field portion B based on the second timing signal T2, and an overlap timing portion is provided between the two (the time T is between TX and TY in FIG. 4). Exists.

In a normal operation in which the first and second control circuits 46 do not receive the release signal, the first timing signal T1 is outputted as it is as the first control signal S1, while the second timing signal T2 is kept as it is. It is output as the second control signal S2.

Returning to FIG. 2, the odd field portion A responds to the first shutter control signal S1 and the vertical synchronizing signal VS to open the shutter at the timing described with reference to FIG. Is stored in the odd field section A, and the stored image data is output as odd field image data VA at a predetermined timing of the vertical synchronizing signal VS.
Sent to 0.

Similarly, the shutter of the even field portion B is opened at the timing according to the second shutter control signal S2, and the image data showing the state of the flow field generated during that time is:
Even field portion B to even field image data VB
And sent to the second accumulation and transfer unit 32.

Each output from the first and second storage and transfer units 30 and 32 is input to a signal synthesis unit 34, where the NTS
It is combined with a television video signal according to the C system, and the combined signal is output as a video output signal VO.

Returning to FIG. 1, the CCD video imaging device 12
The video output signal VO extracted as an output of the digital video output signal DVO is digitized in an analog-to-digital converter (A / D) 20.
Is input to a data processing unit 16 constituted by a known microcomputer, where a memory 16A
The image data processing for the flow velocity measurement is performed according to a predetermined processing program stored in advance in the CPU.

FIG. 5 is a functional diagram showing the contents of the image data processing executed in the data processing unit 16. Data processing unit 1 based on this functional diagram
The image data processing executed in Step 6 will be described.

Before describing the image data processing, the relationship between the trail image based on the odd field image data VA and the trail image based on the even field image data VB will be described with reference to FIG.

FIG. 7A schematically shows a flow image x according to the odd field image data VA, while FIG. 7B shows a flow image y according to the even field image data VB. Is schematically shown.

FIG. 7C shows a superimposed view of FIG. 7A and FIG. 7B. As can be seen from FIG. 7C, the trail image x according to the odd field image data VA and the trail image data y according to the even field image data VB are displaced along the flow direction of the fluid 2, and the time TX And TY overlap.

Returning to FIG. 5, the first data D1 according to the odd field image data VA and the second data D2 according to the even field image data VB are ANDed by the AND operation means 16.
B, where a logical product operation is performed between each stream image according to the first data D1 and each stream image according to the second data D2. Then, data indicating a combination of flow trajectory images having a logical product image according to the logical product operation result is supplied to the flow velocity vector calculating means 16C.

The flow velocity vector calculation means 16C is also provided with the first and second data D1 and D2, and calculates the position of the center of gravity of each flow image based on these inputs. further,
A movement vector of each barycentric position of the pair of trail images is obtained based on the combination data indicating the combination of the trail images. From each movement vector, a flow velocity vector at that point is calculated. Based on the flow velocity vector data indicating the calculated flow velocity vector, the two-dimensional flow velocity distribution of the fluid 2 in the visual field captured by the CCD video imaging device 12 is measured.

Next, the image processing operation will be described in more detail with reference to the flowchart of the image processing program stored in the memory 16A in the data processing unit 16 shown in FIG.

[0032] execution of the image processing program 60 is started, first, in step 62, the digitized video output signal DVO is input, the first and second data D1, D2 are shown in FIG. 7 (a) Are stored in the memory as data respectively showing the first trail image shown in FIG. 7 and the second trail image shown in FIG. 7B.

Next, the routine proceeds to step 64, where data processing for binarizing each image represented by the first and second data D1, D2 is performed. The data processing for binarization is performed by converting each data D1 and D2 into a binary image by using an appropriately set threshold value. The binary data Da and Db shown are obtained.

In the next step 66, unnecessary information is removed, that is, noise removal processing is executed based on the binary data Da and Db. This process includes: (a) a process of completely removing the data of the trail image connected to the frame of the image from each trail. (B) Noise removal processing of the trail image periphery due to expansion and contraction. (C) A process of removing a stream image having a predetermined number of pixels or less as noise. Is included. However, it goes without saying that other appropriate noise removal processing may be performed in addition to or in place of some of them.

Next, in step 68, step 6
Labeling 1a, 1b, 1c,... On each of the flow images in the two flow images left as a result of the noise removal processing of No. 6
. 2a, 2b, 2c,... ((D) of FIG.
See (e)), the calculation of calculation and the area of the center of gravity for all the flow trace image are labeled.

Thereafter, the routine proceeds to step 70, where the logic between each trace image in the trace image obtained by the odd field signal and each trace image in the trace image obtained by the even field signal is determined. The product is calculated.

Next, in step 72, a combination of the label of the trail image in one trail image and the label of the trail image in the other trail image having the result value of the logical product operation is shown. Obtain combination data. For example, if the trace image of the label 1a and the trace image of the label 2a have a correspondence relationship and have the positional relationship shown in FIG. 8, the result of the logical product of these trace images is
Indicates the area of the superimposed portion with medium hatching, and when this area is larger than zero, it is assumed that both trace images are trace images formed by the same tracer particle.

Therefore, in this case, combination data indicating one set of trail images indicated by the labels 1a and 2a is obtained. This calculation is performed for all the combinations, and the combination of the trail images is determined.

In step 74, it is checked whether the following conditions are satisfied in order to determine whether each combination of the trail images obtained as described above is valid. (1) Each of the trail images is associated with only one of the trail images at the other time. (2) A straight line connecting the respective centers of gravity of a set of trace images passes through a logical product image obtained by these. These (1),
Only the combination data that satisfies each condition of (2) is taken as correct combination data, and the combination data that does not satisfy any one of the conditions (1) and (2) is removed.

In step 76, the odd field image data VA, as shown in FIG.
Is calculated from the centroid position W1 of the trajectory image 1a obtained by the above to the centroid position W2 of the trajectory image 2a obtained by the even-numbered field image data VB, and this vector VC is combined with the trajectory image 1a and the trajectory. The average time difference from the image 2a divided by (DB + TB / 2)-(DA + TA / 2) is taken as the flow velocity vector of the fluid 2 at this point. In this way, the flow velocity vector is calculated as described above for the trajectory image indicated by all the combination data.

As a result, the flow velocity vector at each position in the image is clarified. At step 78, the flow velocity distribution is measured based on each flow velocity vector, and the data indicating the flow velocity and the distribution result are output in an appropriate form. Is done. This data may be, for example, an image on a display tube, or the data may be printed out.

As described above, in the apparatus shown in FIG. 1, the required flow field is obtained as an odd field image and an even field image in a single CCD image pickup device.
The odd field portion A and the even number field of the CCD solid-state imaging device 20
Timing of charge accumulation with the field B (shutter tie
Ming) was set as described with reference to FIG.
And visualized in the first field image signal.
The image of the flow and the image in the second field image signal
The visualized flow images are the one-frame images
Have overlapping parts when synthesized as
The difference between the first time and the second time.
Images do not overlap by the amount corresponding to the exposure time difference
Parts arise. Therefore, this causes the first fee
Image in the second field image and the image in the second field image.
Easily grasp the correspondence between the image and the moving direction of each image.
Wear.

Therefore, by appropriately setting the shutter opening timings, the correspondence between the two trajectory images and the logical product between them can be determined regardless of the moving direction and the moving speed of the tracer particles. Can be found very easily by calculating

For this reason, the measurement time is set to the NTSC TV
Since it is not restricted by the image sampling period, it is possible to measure the flow velocity and the flow velocity distribution of the flow field extremely simply and quickly by simple processing.

[0045]

According to the present invention, as described above, a CCD for obtaining a television image signal of a flow field to be measured is provided.
Construct one frame image signal using video imaging device
Between each of the flow images according to the two field image signals , an overlapping portion can be generated between a corresponding set of the flow images, and the correspondence between the respective flow images is determined by the logic of the data indicating each of the flow images. In addition to being very convenient to easily determine by product operation, the flow image in each flow image can be used to measure the flow velocity etc. without being affected by the sampling cycle of the TV image, the moving speed and direction of the tracer. The required flow field can be accurately imaged.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a flow velocity measuring device using a CCD video imaging device according to the present invention.

FIG. 2 is a detailed block diagram of the CCD video imaging device of FIG.

FIG. 3 is a detailed block diagram of first and second control units in FIG. 2;

FIG. 4 is a waveform chart for explaining the operation of the first and second control units shown in FIG. 3;

FIG. 5 is a functional diagram showing a configuration of a data processing unit in FIG. 1;

FIG. 6 is a flowchart showing an image processing program executed in the data processing unit of FIG. 1;

FIG. 7 is a view showing a trail image for explaining image processing in the apparatus of FIG. 1;

FIG. 8 is an explanatory diagram for calculating a logical product of flow images and calculating a velocity vector, which is executed in the apparatus of FIG. 1;

[Explanation of symbols]

 Reference Signs List 2 fluid 12 CCD video imaging device 20 CCD solid-state imaging device 24 First control unit 26 Second control unit S1 First shutter control signal S2 Second shutter control signal A Odd field part B Even field part VA Odd field image data VB Even field image data

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 5/30-5/335 G01P 13/00

Claims (1)

(57) [Claims] 1. A CCD video imaging device for obtaining a television image signal of a flow field in order to obtain two-dimensional flow velocity information of the flow field visualized by injecting a tracer. light - it can be taken out more than one field image signal comprises an electromechanical transducer 2 Tsunofu
1 frame video image signal by field image signal
A CCD solid-state imaging device so as to constitute a first field constituting a video image signal of one frame
The video signal is the corresponding vertical synchronization signal generation timing.
From the exposure start timing delayed by a predetermined time
Exposure end timing set when time elapses
To perform exposure and take out from the CCD solid-state imaging device.
A first shutter control means, and a second filter constituting the video image signal of one frame.
The corresponding vertical synchronization signal generation timing
Exposure start timing delayed by the predetermined time
When a second time that is longer than the first time elapses
Exposure is performed until the exposure end timing set in
Second shutter control for taking out from CD solid-state imaging device
CCD video imaging device being characterized in that a means.