Pattern counting system using line scanning

• US 4,000,399 A
• Filed: 12/23/1974
• Issued: 12/28/1976
• Est. Priority Date: 12/28/1973
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nippon Kotsu Kabushiki Kaisha (Nikon Corporation)
• Inventors: Kawahara, Atsushi
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US05/536,035
• Time in Patent Office: 736 Days
• Field of Search: 235/92 PC, 340/146.3 MA, 340/146.3 H, 340/146.3 AC, 340/146.3 J, 340/146.3 Y, 340/146.3 CA
• US Class Current: 377/10
• CPC Class Codes: G06M 11/04 with provision for distinguishing between different sizes of objects investigating particle size in general G01N15/00

Abstract

A system for counting patterns in which each pattern in a scanning field is scanned along successive scanning lines and is sampled at successive points along each line to produce binary signals indicative of the presence or absence of the pattern at each sampling point. In order to avoid the problem of pores (holes or voids) in the patterns and the problem of concave pattern portions as seen in a given viewing direction perpendicular to the scanning direction, the digitized signals representing the original patterns are employed to produce mask signals which effectively eliminate the pores and concave pattern portions and which permit each pattern to be counted by counting a portion of the pattern that is convex as seen in the said viewing direction.

Claims

1. In a system for counting patterns by sampling the patterns at successive sampling points along successive scanning lines and producing a digital signal at each scanning point depending upon the presence or absence of the pattern at such points, the improvement comprising means responsive to the digital signals for producing corresponding mask signals which eliminate pattern pores and concave pattern portions, and means responsive to the mask signals corresponding to successive scanning lines for counting a convex portion of each pattern and thereby counting the number of patterns.

2. A system in accordance with claim 1, wherein said means for producing said mask signals comprises first means for storing the digital signals produced by the sampling at successive sampling points along one scanning line, second means for storing mask signal elements for corresponding sampling points along the preceding scanning line, third means for storing mask signal elements for corresponding sampling points along said one scanning line, mask signal element generating means responsive to signals stored in said first and second storing means for generating the mask signal elements stored in the third storing means, means for transfering the mask signal elements stored in the third storing means to the second storing means, and means for reading out the mask signal elements stored in the second and third storing means and for applying the same to said counting means.

3. A system in accordance with claim 2, wherein said storing means comprise shift registers having successive stages for storing successive digital signals or mask signal elements, said first and second storing means comprising serial-input, parallel-output shift registers, said third storing means comprising a parallel-input, serial-output shift register, and said second shift register also having a serial output, said serial outputs being applied to said counting means.

4. A system in accordance with claim 1, wherein said counting means comprises means for comparing successive mask signals.

5. A system in accordance with claim 1, wherein said mask signal producing means comprises successive mask signal element generators, each comprising a logic circuit having the configuration shown in FIG. 3.

6. A system in accordance with claim 1, wherein said mask signal producing means comprises successive mask signal element generators, each having logic means operating in accordance with the following logic equation:

space="preserve" listing-type="equation">M.sub.i.sup.n.sup.+1 = (S.sub.i.sup.n.sup.+1 + L.sub.i.sub.+1) . (S.sub.i.sup.n.sup.+1 + R.sub.i.sub.-1)

where n represents any scanning line, i represents any sampling point on a scanning line, M represents a mask signal element for a designated scanning line and sampling point thereon, S represents a digital signal for a designated scanning line and sampling point thereon, and L and R are defined by the following logic equations;

space="preserve" listing-type="equation">Li = M.sub.i.sub.-1.sup.n . (S.sub.i.sup.n.sup.+1 + L.sub.i.sub.+1)

space="preserve" listing-type="equation">Ri = M.sub.i.sub.+1.sup.n . (S.sub.i.sup.n.sup.+1 + R.sub.i.sub.+1).

7. A system in accordance with claim 1, wherein said mask signal producing means comprises means for producing right and left mask signals M_Riⁿ⁺¹ and M_Li^N+1, respectively in accordance with the following logic equations:

space="preserve" listing-type="equation">M.sub.Ri.sup.n.sup.+1 = S.sub.i.sup.n.sup.+1 + R.sub.i.sub.-1

space="preserve" listing-type="equation">M.sub.Li.sup.n.sup.+1 = S.sub.i.sup.n.sup.+1 + L.sub.i.sub.+1

where n represents any scanning line, i represents any sampling point on a scanning line, M represents a mask signal element for a designated scanning line and sampling point thereon, S represents a digital signal for a designated scanning line and sampling point thereon, and L and R are defined by the following logic equations;

space="preserve" listing-type="equation">Li = M.sub.i.sub.-1.sup. n . (S.sub.i.sup.n.sup.+1 + L.sub.i.sub.+1)

space="preserve" listing-type="equation">Ri = M.sub.i.sub.+1.sup.n . (S.sub.i.sup.n.sup.+1 + R.sub.i.sub.-1)

and means for producing the logic product of said right and left mask signals.

8. A system in accordance with claim 1, wherein said means for producing said mask signals comprises a first storage device for storing the digital signals produced by the sampling at successive sampling points along one scanning line, successively in a scanning direction, a second storage device for storing mask signal elements for the corresponding sampling points of the preceding scanning line, successively in said scanning direction, a first mask signal generator for receiving signals from said first and second storage devices and generating a mask signal for said one scanning line in said scanning direction, a third storage device for storing digital signals produced by the sampling of said one scanning line at said sampling points thereof, successively in a direction opposite to said scanning direction, a fourth storage device for storing mask signal elements for said corresponding sampling points of said preceding scanning line, successively in said opposite direction, a second mask signal generator for receiving said signals from said third and fourth storage devices and generating a mask signal for said one scanning line in said opposite direction, means for producing the logic product of the mask signal in said scanning direction and the mask signal in said opposite direction, means for connecting the output of said product-producing means to said second and fourth storage devices as an input thereto, and means for connecting said output of said product-producing means and said second storage device to said counting means.

9. A system in accordance with claim 1, wherein said mask signal producing means comprises a circuit having the configuration of FIGS. 6A-6B.