JP2552838B2 - Multi electron beam imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus, and more particularly to a multi-electron beam imaging apparatus using a plurality of electron beam sources.

[Conventional technology]

As the electron emission source of this type of device, conventionally, for example,
JP-B-54-30274, JP-A-54-111272 (U.S. Pat.No. 4,259,678), JP-A-56-15529 (U.S. Pat.No. 4,303,930), or JP-A-5-30
It is disclosed in JP-A-7-38528.

Further, the multi-electron beam imaging tube is disclosed in the specification of a multi-electron beam imaging tube filed by the present applicant and filed by the same inventor as the present inventors.

Here, finding (matching) a position where a specific pattern exists in a given image is an important technique in various application fields. For example,
There is no end to the examples, such as finding the position of a specific character in the original image of a printed matter, or finding and tracking a target object in the image obtained from the monitoring system.

As a matching method, it is typical to repeat obtaining a cross-correlation between a certain part of an image and a specific pattern.

Hereinafter, how to perform matching using cross-correlation in the field of digital image processing will be briefly described with reference to the algorithm explanatory diagrams shown in FIGS. 5A and 5B.

In FIG. 5 (a), the images F _I , _J (I ...
1 to K, J from · · 1 to L) in, (b) magnitude Kl pattern G _I as shown in _{FIG., J (I ·· 1~k, J} ·· 1
~ L) shall be found. Basically, pattern G
Is superposed on a certain position of the image F, the difference for each corresponding pixel is calculated, and the total sum is calculated.
It is determined that the target pattern exists at this position. If this basic operation is performed on the entire screen of the image G, the purpose can be achieved. For example, in FIG.
At P ₁ , the error is large and it is determined that the pattern is not the target pattern, and at position P _K the error is zero and it is determined that the target pattern exists.

Next, let us estimate the amount of calculation required when performing matching by such cross-correlation. To perform one cross-correlation, K ₁ subtractions and K _1-1 additions, or about 2K ₁ operations are required. Since this has to be performed K × L times for almost the number of pixels of the image G, 2K ・ L ・ K ₁
It is necessary to calculate once.

[Problems to be solved by the invention]

However, here, for example, K = L = 51
2. When k = l = 5, assuming that the calculation is executed in 1 microsecond, the time required for matching is about 7 seconds, and when the size of the image and the size of the pattern become larger, The method is not very satisfactory, and it cannot deal with moving images at all.

Therefore, in the method of obtaining the cross-correlation, when the total value of the differences exceeds the allowable value, the processing for obtaining the remaining differences is terminated,
Some ideas such as recommending the pattern to the next position have been made. However, even in this case, a special processor is far from being practically used, and it is the current situation.

The present invention has been made by paying attention to the problems of the conventional example as described above, and an object thereof is to influence a multi-electron beam imaging apparatus capable of performing high-speed processing while eliminating the above-mentioned defects.

[Means for solving problems]

Therefore, in the present invention, a target electrode on which a subject image is formed, an electron beam generator having a plurality of electron beam generators arranged on a matrix, and an electron beam generated by the electron beam generator are Scanning means for scanning the target electrode; storage means for storing a plurality of shape patterns; selection means for selecting one of the plurality of shape patterns stored in the storage means;
Drive control means for driving and controlling the electron beam generation source with the shape pattern selected by the selecting means; and an electron beam of the shape pattern is applied to the target electrode by the drive control means, and the electron beam is emitted by the scanning means. By providing a multi-electron beam imaging apparatus having a detection unit that detects the position of the shape pattern existing in the subject by measuring the current flowing through the target electrode when the beam is scanned on the target electrode. It is intended to achieve the above object.

[Action]

With the configuration / control method as described above, matching calculation by cross-correlation can be performed in an extremely short time.

〔Example〕

Hereinafter, the present invention will be described based on Examples. FIG. 1 is an explanatory view of a method for obtaining a cross correlation according to the present invention, and FIG.
FIG. 1 shows a schematic configuration diagram of an example of a multi-electron beam imaging tube used in the present invention.

(Structure of Image Pickup Tube) (FIG. 2) First, an outline of the structure of the image pickup tube used in the present invention will be described. The PEC is a photoelectric conversion unit, and has a laminated structure of a transparent substrate FP, a transparent conductive film TSP, and a photoconductor layer PC. Also,
The electron beam generator SEG comprises a plurality of electron beam generators arranged in a matrix of M rows × N columns. Also,
ENBL is an electron beam emission enable signal given to the electron beam generator (source) SEG, EB is the generated electron beam,
MM is the number of horizontally divided pixels when the photoconductor PC surface is horizontally divided by the horizontal effective diameter of the electron beam EB, NN is the vertical effective diameter of the electron beam EB, and the photoconductor PC surface is It is the number of vertically divided pixels when divided in the vertical direction. OUT is an output terminal for the target current flowing through the transparent conductive film TSP when a certain position on the photoconductor PC is irradiated with the electron beam BE, and DYC is a horizontal deflection electrode that horizontally deflects the electron beam EB. , DYR is a vertical deflection electrode that vertically deflects the electron beam EB, and PM is a pattern memory that stores a pattern to be correlated, and is connected to each of the multi-electron beam generation sources.

(Cross-correlation algorithm) Now, assuming that the subject is forming an optical image on the photoconductor layer PC through the lens system, it corresponds to the optical image on the photoconductor layer PC upper layer due to the operation principle of the well-known vidicon image pickup tube. It is exchanged for charge distribution. This is shown schematically in Fig. 1. The optical image IMG of the object OBJ shows the photoconductor layer PC.
The upper charge is distributed as shown by the dashed curve QC. On the other hand, the pattern memory PM stores a pattern to be found in the image, and according to this pattern, a part of the electron beam generation source SEG emits an electron beam.
FIG. 1 EB shows the electron beam emitted according to this pattern. Now, the principle of obtaining the cross-correlation between the pattern and the image with the above configuration is to control the voltage applied to each deflection electrode DYR, DYC as shown in FIG.
The photoelectric conversion unit PEC may be scanned with. That is, if the electron beam group does not match the designated pattern by scanning as shown in FIG. 1 EBO, the target current obtained from the output terminal OUT is small, and conversely, if it matches as shown by EBI, the current is large. can get.

It should be noted here that in the case of the storage type image pickup tube as shown in FIG. 2, once the electron beam group EB is applied to a certain area, the charge information in that area is initialized. That is. That is, when the electron beam group EB is simply deflected horizontally or vertically, immediately before in the horizontal direction, one horizontal scanning time before in the vertical direction,
An accurate correlation cannot be obtained because the region overlaps with the region for which the electron beam is used for correlation and electric charge is not yet sufficiently accumulated in the overlapped portion. In order to solve this, scanning is performed with the size of the pattern as a unit (called block scanning), and when one block scanning is completed, the origin of the block scanning is moved by one pixel of the pattern and again, The block scanning of the entire screen may be repeated.

3 (a), (b), and (c) are diagrams for explaining this block scanning method, in which, in this example, the size of the pattern, that is, the area irradiated with a plurality of electron beams at the same time is measured vertically and horizontally. Both are set to 2. When the photoconductor layer PC of the photoelectric conversion unit PEC is divided according to the size of this pattern, it becomes as shown by the broken line. Now, first, as shown in FIG.
Block scanning is performed once from the region S to the region E, and in the next scanning, block scanning is performed with the (2,1) position horizontally shifted by one pixel of the pattern as the origin, as shown in FIG. ing. That is, the area S'or the area E'is scanned to check the correlation. FIG. 6C shows a state where the block scanning origin is set to the position (2, 2).

FIG. 4 is a block diagram of a control circuit for performing the above scanning. CLK is a basic clock for scanning the generated electron beam BE, MCT is a M-ary counter equal to the number M in the horizontal direction of the multi-electron beam source SEG, NCT is the number in the vertical direction of the multi-electron beam source SEG. An N-ary counter equal to N, MMCT, subtracts the number M in the horizontal direction of the multi-electron beam generation source SEG from the number MM of horizontally divided pixels (MM
-M) -adic counter, NNCT is a (NN-N) -adic counter obtained by subtracting the number N in the vertical direction of the multi-electron beam generation source SEG from the number NN of vertically divided pixels, and the carry of the counter MMCT, respectively. Is the input clock of the counter NNCT,
The carry of the counter NNCT is the input clock of the counter MCT, and the carry of the counter MCT is the input clock of the counter NCT. The ADC is an MM-bit AD converter, the lower M bits of which are connected to the output of the counter MCT, and the above (MM-M) bits are connected to the output of the counter MMCT. The analog output is amplified by the amplifier AMPC. And is supplied to the deflection electrode DYC. Similarly, ADR is NN bit
An AD converter, the lower N bits of which are connected to the output of the counter NCT and the output of the (NN-N) bit counter NNCT, whose analog output is amplified by the amplifier AMPR and supplied to the deflection electrode DYR. To be done. Also, the basic clock CLK
Is inverted by an inverter INV and supplied as an electron beam emission enable signal.

The operation of the circuit of FIG. 4 is clear from the above description using FIG. 3, but each counter MMCT, NNCT is the part that performs block scanning, and each counter MCT, NCT is the origin of block scanning. Play a role in moving. Further, the enable signal ENBL prohibits the irradiation of the electron beam BE while deflecting the electron beam group from one area to the next area, and irradiates the electron beam BE after the position for accurately obtaining the correlation is determined. Is.

Next, the time required for the cross-correlation calculation will be estimated by the above embodiment. For example, 512 as an image
Assuming x512 pixels, 5x5 pixels as a pattern, and 1/30 seconds of accumulation time, it can be calculated in about 0.8 seconds. Further, this accumulation time does not always need to be set to 1/30 second, and it can be shortened as much as the S / N ratio allows, and the speed can be further increased.

(Other Embodiments) In the above embodiment, the control circuit is configured by using the pattern memories PM vertical and horizontal sizes M and N as they are for simplicity.
In practice, it is possible to use the sizes m and n (m ≦ M, n ≦ N) of the exterior quadrangle of the pattern stored in the pattern memory PM. In this case, it is necessary to configure all the counters in FIG. 4 as programmable counters, but the cross-correlation can be calculated faster.

Further, in the above description, a storage type image pickup tube such as a vidicon image pickup tube is assumed, but it is also applicable to a non-storage type image pickup tube. In this case, the scanning control as shown in FIG. A circuit becomes unnecessary, and cross-correlation calculation can be performed with a simpler configuration.

〔The invention's effect〕

As described above, according to the present invention, each electron beam generation source of an image pickup tube in which multiple electron beam generation sources are arranged in a matrix is driven in a predetermined pattern to control the generation and deflection of electron beams. With this configuration, it is possible to perform a cross-correlation calculation that has conventionally required a long time for processing in an extremely short time, and the effect is extremely large.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for obtaining a cross-correlation according to the present invention, FIG. 2 is a schematic view of the configuration of a multi-electron beam imaging tube,
3 (a), (b), and (c) are explanatory diagrams of the block scanning method, FIG. 4 is a block scanning control circuit block diagram, and FIGS. 5 (a) and 5 (b) are cross-correlation algorithms. FIG. PEC: Photoelectric conversion unit PC: Photoconductor layer (imaging surface) SEG: Electron beam generator (source) EB, EBI / EBO: Electron beam DYC / DYR: Horizontal / vertical polarization electrode OBJ: Subject OUT: Target current output terminal

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Nobutoshi Mizusawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ryuichi Arai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Yasuhiko Ishiwata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP 63-105439 (JP, A) JP 63-105576 (JP , A) JP-A-63-107374 (JP, A)

Claims (1)

(57) [Claims] 1. A target electrode on which a subject image is formed, an electron beam generator having a plurality of electron beam generators arranged on a matrix, and an electron beam generated by the electron beam generator is applied to the target electrode. Scanning means for scanning with respect to each other, storage means for storing a plurality of shape patterns, selection means for selecting one of the plurality of shape patterns stored in the storage means, and selection by the selection means Drive control means for driving and controlling the electron beam generation source with the formed shape pattern, and the drive control means for irradiating the target electrode with the electron beam of the shape pattern, and the scanning means for applying the electron beam to the target electrode. The shape existing in the object is measured by measuring the current flowing through the target electrode when scanned against Multiple electron beam imaging apparatus having a detection means for detecting the position of the pattern.