Image analysis counting system

• US 4,962,538 A
• Filed: 06/07/1989
• Issued: 10/09/1990
• Est. Priority Date: 02/13/1989
• Status: Expired due to Fees

• Current Assignee: Comar Limited (Nabors Industries Limited)
• Original Assignee: Comar Limited (Nabors Industries Limited)
• Inventors: Moorehead, Robert M., Eppler, Susan G.
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): Razavi, Michael
• Application Number:
  US07/348,710
• Time in Patent Office: 489 Days
• Field of Search: 382/1, 382/8, 382/28, 382/67, 382/65, 250/222.2, 250/223 R, 250/560, 356/381, 356/382, 356/383, 356/385, 356/386, 356/387, 377/53, 377/6, 377/8
• US Class Current: 382/141
• CPC Class Codes: G06M 1/101 by electro-optical means
• CPC Class Codes: G06M 2207/02 Counting of generally flat and overlapped articles, e.g. cards, newspapers
• CPC Class Codes: G06M 7/10 Counting of flat overlapped articles, e.g. of cards

Abstract

A system for counting overlapped newspapers carried on a moving conveyor which employs an optical sensor which is passive in nature. Accurate count is obtained by image analysis of the image presented by the edge of the newspaper flow as the image is focused on a linear CCD array. Definitive values are determined which are quantitative of the top profile, height, of the newspapers. The processing technique employed determines the rate of change of the height of the image and utilizes the rate of change data to output a newspaper count increment when the rate of change, derivative, of top profile height changes from a positive value to a negative value and the measured profile height exceeds a calibrated value thickness, and outputs two newspaper count increments when the measured profile height exceeds a second calibrated value thickness.

Claims

1. A system for obtaining a count of overlapped newspapers carried on a moving conveyor comprising:

first means for optically focusing the side image of the newspapers on a transversely oriented linear detector array;

second means for serially shifting analog outputs at a clock defined rate from said detector array to differential amplifier means for removing the DC offset therefrom;

third means receiving the output from said differential amplifier means and for converting said differential amplifier means output to a serial digital output signal as defined by a selected light level,

a serial-in/parallel-out shift register receiving said third means output signal,

a microprocessing means for developing an image top profile value of the newspaper flow image as it appears in said photodetector array based upon the output of said shift register;

means for comparing the difference between successive newspaper image top profile values to obtain a derivative of successive image top profile values;

means for initiating a newspaper count output when the rate of change of successive image top profile values change from positive to negative; and

means to develop a newspaper thickness definite value, said newspaper count output comprises a single count increment when said newspaper thickness definitive value exceeds a calibrated thickness value and said newspaper count output comprises a double count increment when said measured newspaper thickness exceeds a second calibrated thickness value.

2. The system defined in claim 1 wherein said means for optically focusing the side image of the newspapers on said linear detector array comprises a light source, a light shielding member having an elongated through-slot formed therein, said slot being oriented transverse of the surface of the newspaper conveyor, a lens system oriented along the line of sight between said slot and said linear detector array, said lens system focusing the slot defined image of the side edges of the newspapers on said linear detector array, said light source being angular oriented with respect to the line of sight between said detector array and the side edge of the newspapers whereby light beyond a predetermined depth of field defined by said lens system is well below the adjustable threshold detection level and the side edges of the newspapers are focused on said linear detector array are illuminated.

3. A system for obtaining a count of overlapped newspapers having side edges carried on a moving conveyor comprising,

a linear CCD array oriented transversely of the side edges of said newspapers for optically focusing the side image of said newspapers on said linear CCD array,

means for continuously serially shifting outputs from said photodetector array at a clock defined rate,

signal processing means for receiving said serially shifted outputs from said linear CCD array,

said signal processing means comprising means for developing clock defined repetitive sequential digital values definitive of the top profile of said newspapers as said newspapers are conveyed past said linear CCD array,

means for comparing each of said digital values with the next preceding one of said digital values to obtain derivative value of the top profile of said newspapers,

means for initiating a newspaper count output increment when said derivative value change from positive to negative,

means to develop a newspaper thickness definite value from a comparison between the previous newspaper top profile and the existing newspaper top profile value, and difference value calculated from sample to sample changes from positive to negative of the existing newspaper, said newspaper count output comprising a single count increment when said newspaper thickness definitive value exceeds a calibrated value thickness, and said newspaper count output comprising a double count increment when said newspaper thickness value exceeds a second calibrated value thickness.

4. The system define in claim 3 wherein said means for optically focusing the side image of said newspapers on said linear CCD array comprises a light source, a light shielding member having an elongated through-slot formed therein, said slot being oriented transverse of the surface of said newspaper conveyor, a lens system oriented along the line of sight between said slot and said linear CCD array, said lens system focusing the slot defined image of the side edges of said newspapers on said linear CCD array, said light source being angular oriented with respect to the line of sight between said linear CCD array and the side edge of said newspapers whereby light beyond a predetermined depth of field defined by said lens system is well below the adjustable threshold detection level and the side edges of said newspapers are focused on said linear CCD array are illuminated.

5. A method of obtaining a count of overlapped newspapers carried on a moving conveyor by image analysis of the image of the side edges of said newspaper as the focused image impinges on a linear CCD array oriented transversely of said newspaper side edges, comprising the repetitive sequential steps of:

serially shifting analog outputs from the linear CCD array and a reference light level output to a differential amplifier to remove the D.C. offset therefrom, amplify and filter high frequency noise therefrom;

converting the analog output signal from said differential amplifier to a serial digital output signal as defined by a selected light level;

applying said serial digital output to a serial in/parallel out shift register;

storing the parallel output from said shift register in a random access memory;

transferring data in said random access memory to a microprocessor for developing a value definitive of the top profile of the newspaper image as it appears on the photodetector array;

obtaining the difference between successive newspaper image top definitive value to obtain a value definitive of the rate of change of said top definitive values;

determining the thickness of the newspapers when the rate of change of said top definitive value changes from positive to negative;

initiating a single count increment when the rate of change of successive top definitive counts goes from positive to negative and the measured thickness of the newspapers exceeds a first calibrated value thickness; and

initiating a double count increment when the rate of change of successive top definitive values changes from positive to negative and the measured thickness of the newspapers exceeds a second calibrated value thickness.