Apparatus for counting numbers of fine particles

An apparatus for counting numbers of fine particles, comprising:

• transparent sample plate means for containing a sample of fine particles to be counted, said sample plate means having a shape adapted to arrange said fine particles all on the same level across said plate without superposition;
• an optical system adapted to irradiate parallel light beams along an optical axis through said sample plate means for producing optical silhouetted images of said fine particles contained thereon and for magnifying and projecting said silhouetted images, and having self scanning charge coupled device (CCD) photoelectric converter means including a plurality of photoelectric elements arranged operably in a linear row array, said projected silhouetted images of said fine particles being magnified such that a projected image of a single fine particle has a dimension in the range of from one to five microns so as to substantially cover a single said photoelectric element, said photoelectric converter means being adapted to convert said magnified silhouetted images of said fine particles projected onto said photoelectric elements thereof into signal charges, said signal charges being transferred serially along the direction of said linear row array;
• drive means adapted to cause scanning motion of said sample plate means in a plane perpendicular to said optical axis of said optical system and in a direction perpendicular to said direction of said linear row array, and at a speed permitting scanning by said photoelectric converter means in said direction of said linear row array of said silhouetted images projected thereon as said sample plate means is moved, said drive means including sample holder means for holding said sample plate means, synchronous motor means operably coupled to said sample holder means for driving said sample holder means and spring means urging said sample holder means toward a direction in which said motor means drives said sample holder means, the urging force of said spring means on said sample holder being equal or greater than a rated driving torque of said motor means to a degree necessary for maintaining synchronous rotation of said motor means;
• and
• counting and output means for counting the numbers of said signal charges transferred serially along the direction of said linear row array of said photoelectric converter means which have a charge value greater than a predetermined charge threshold value and for summing said numbers of said charge signals exceeding said threshold value during said scanning motion of said sample plate means, and for outputting an output data signal representative of said summed number of said charge signals exceeding said threshold value.