Abstract Apparatus for assessing the quality of printed characters on a record has a document support arranged beneath a scanning head. The scanning head has a lens arranged to oscillate in a direction parallel to the vertical axis of characters printed on the document. The lens is arranged to focus a character to be evaluated on to a set of photoelectric strips arranged side-byside in a direction perpendicular to the oscillatory movement of the lens, so that a character image is scanned in vertical strips. The lens moving arrangement also has a timing pulse generator so that the character scan is broken into notional zones which, in conjunction with the orientation of the photoelectric strips enables a matrix representation of the recorded character to be generated. The separate output signals from the photoelectric strips are passed to shifting registers whose stages are connected to a storage matrix capable of selecting an idealised character form to be compared with the scanned character. The comparison is carried out over a number of scanning cycles while the position of the document carrying the character is changed and an indication is provided of the least deviation of the scanned character from the idealised character form during the change. The clock pulse generator is arranged so that non-linear clock pulses are generated from a harmonic scan. Signals from a velocity transducer are utilized to drive a voltage controlled pulse generator whose output frequency is proportional to the input voltage.
Scan control apparatus for generating timing signals, including; means for repeatedly scanning in sequence a succession of adjacent areas of similar extent, the scanning means comprising: a static photosensitive device; an optical imaging system positioned between the photosensitive device and the areas to be scanned; and means for oscillating the optical system at a nonuniform velocity to image successive ones of the areas on to the photosensitive device as the system moves during each halfcycle of oscillation; velocity sensing means coupled to the scanning means and responsive to movement of the optical system to produce a velocity signal having a magnitude varying in accordance with the variation in velocity of the system and a polarity dependent on the direction of movement of the system during each successive half-cycle of oscillation; means for generating a succession of timing signals; and circuit means associated with the timing signal generator responsive to the velocity signal to control the generation of each of the successive timing signals to occur respectively in synchronism with the scanning of the successive adjacent areas and responsive to said polarity to render effective only those parts of the velocity signal produced during alternate halfcycles of oscillation to inhibit the generation of timing signals except during movement in a predetermined direction.
Claim 2
Dependent Claim
211 words
Scan control apparatus for generating timing signals, including; means for repeatedly scanning in sequence a succession of adjacent areas of similar extent, the scanning means comprising: a static photosensitive device; an optical imaging system positioned between the photosensitive device and the areas to be scanned; and means for oscillating the optical system at a nonuniform velocity to image successive ones of the areas on to the photosensitive device as the system moves during each halfcycle of oscillation; velocity sensing means coupled to the scanning means and responsive to movement of the optical system to produce a velocity signal having a magnitude varying in accordance with the variation in velocity of the system and a polarity dependent on the direction of movement of the system during each successive half-cycle of oscillation; means for generating a succession of timing signals; and circuit means associated with the timing signal generator responsive to the velocity signal to control the generation of each of the successive timing signals to occur respectively in synchronism with the scanning of the successive adjacent areas and responsive to said polarity to render effective only those parts of the velocity signal produced during alternate halfcycles of oscillation to inhibit the generation of timing signals except during movement in a predetermined direction.
Claim 3
Dependent Claim
110 words
Scan control apparatus for generating timing signals including; a cyclic scanning system moveable throughout a succession of scanning cycles at a non-uniform velocity; means for generating an electrical signal of magnitude proportional to the velocity of the scanning system; a variable frequency electrical oscillator; and circuit means to control the oscillator in response to said electrical signal to vary the oscillator frequency in proportion to the magnitude of the signal to produce an output train consisting of a plurality of timing pulses for each scanning cycle in which in each scanning cycle the pulses are uniformly spaced with respect to the scanning system movement and are non-uniformly spaced in time.
Claim 4
Dependent Claim
110 words
Scan control apparatus for generating timing signals including; a cyclic scanning system moveable throughout a succession of scanning cycles at a non-uniform velocity; means for generating an electrical signal of magnitude proportional to the velocity of the scanning system; a variable frequency electrical oscillator; and circuit means to control the oscillator in response to said electrical signal to vary the oscillator frequency in proportion to the magnitude of the signal to produce an output train consisting of a plurality of timing pulses for each scanning cycle in which in each scanning cycle the pulses are uniformly spaced with respect to the scanning system movement and are non-uniformly spaced in time.