DIGITAL PRODUCTS INSPECTION SYSTEM

• US 3,651,315 A
• Filed: 05/14/1970
• Issued: 03/21/1972
• Est. Priority Date: 05/14/1970
• Status: Expired due to Term

• Current Assignee: Arthur A. Collins
• Original Assignee: Arthur A. Collins
• Inventors: Collins, Arthur A.
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Dildine, Jr., R. Stephen
• Application Number:
  US05/037,320
• Time in Patent Office: 677 Days
• Field of Search: 235/151.31 324/73R,73AT,73PC
• US Class Current: 714/736
• CPC Class Codes: G01R 31/318385 Random or pseudo-random test pattern
• CPC Class Codes: G01R 31/3193 with comparison between actual response and known fault free response receiver details G01R31/31924

Abstract

A Digital Product Inspection System using a digital pseudorandom generator in combination with a charactertistic of the product being inspected to produce a unique set of data combinations which when compared with previously taken data from the test of a '"'"''"'"''"'"''"'"'known good unit'"'"''"'"''"'"''"'"' will provide an output indicating whether or not the characteristic of the unit under test is within acceptable limits.

Claims

1. A method of testing electronic devices comprising the steps of:

initializing a known good electronic device of the type to be tested by supplying a first predetermined sequence of data words to said known good electronic device to place said known good device in a predetermined condition;

circulating a second sequence of data words, starting with a given data word, around a loop comprising said known good unit and a transfer function;

altering said circulating data words by said transfer function to provide a sequence of repeatable alterations on said circulating data word for all electronic devices which respond in the same manner to data words circulating therethrough;

sampling said data word every Nth circulation thereof;

storing said sampled data words;

initializing an electronic device to be tested to have the same predetermined condition as said known good device after initialization;

circulating a third sequence of data words, starting with said given data word, around said loop comprising said electronic device being tested and said transfer function;

sampling said third sequence of circulating data every Mth circulation thereof; and

comparing said Mth sampled circulating data word of said third sequence of circulating data words with the Nth sampled stored data of said second sequence of circulating data words to determine coincidence or non-coincidence of said data words being compared, where M represents time-corresponding successive samplings.

2. The method of testing electronic devices with testing equipment comprising the steps of:

initializing a known good unit to a predetermined condition;

characterizing said known good unit;

initializing a unit under test to said predetermined condition;

testing said unit under test;

said initializing steps each comprising the steps of;

supplying a predetermined sequence of instruction words to the testing equipment to prepare said testing equipment for characterization or testing; and

supplying a predetermined sequence of data words to the unit under test to place said unit under test in said predetermined condition;

said characterizing step and said testing step each comprising the steps of;

circulating a predetermined data word around a loop comprising the unit under test and a transfer function; and

altering the data words as they pass through said transfer function in a repeatable manner in response to any given sequence of data words supplied thereto; and

comparing at least one of the resulting data words in said characterizing step with the corresponding data words in the testing step.

3. A method of testing electronic devices comprising the steps of:

initializing a known good electronic device of the type to be tested to place said known good device in a predetermined condition;

circulating a first sequence of data words, starting with a given data word from the output means of the known good electronic device, through a data word transfer function having a given initial condition, and back to the input means of the known good electronic device;

mutually altering the circulating data word and the transfer function by each other each circulation of the data word through the transfer function to produce at the output of said transfer function a sequence of repeatable data words for all electronic devices which respond in the same manner to data words circulating therethrough;

sampling said first sequence of circulating data words in predetermined counts of circulations thereof;

storing said sampled data words;

initializing an electronic device to be tested to have the same predetermined condition as said known good device after initialization;

circulating a second sequence of data words, starting with said given data word, from the output means of said electronic device being tested, through said transfer function having said initial given condition, and back to the input means of said electronic device being tested;

sampling said second sequence of circulating data words for the same predetermined counts of circulation thereof as for the first sequence of sampling; and

comparing said sampled data words of said second sequence of circulating data words with the corresponding sampled stored data words of said first sequence of circulations of data words to determine coincidence or non-coincidence of said data words being compared.

4. A method of testing electronic devices comprising the steps of;

initializing a known good electronic device of the type to be tested to place said known good device in a predetermined condition;

circulating a first sequence of data words, starting with a given data word, around a loop comprising said known good unit and a transfer function;

mutually altering the circulating data word and the transfer function by each other each circulation of the data word through the transfer function to produce at the output of said transfer function a sequence of data words which is repeatable for all electronic devices which respond in the same manner to data words circulating therethrough;

sampling every Nth circulation of said circulating data word;

storing said sampled data words;

initializing an electronic device to be tested to have the same predetermined condition as said known good device after initialization;

circulating a second sequence of data words, starting with said given data word, around said loop comprising said electronic device being tested and said transfer function;

sampling said second sequence of circulating data every Mth circulation thereof; and

comparing said Mth sampled data word of said second sequence of circulating data words with the Nth sampled stored data word of said first sequence of circulating data words to determine coincideNce or non-coincidence of said data words being compared.

5. A method of testing electronic devices comprising the steps of:

initializing a known good electronic device of the type to be tested by supplying a first predetermined sequence of data words to said known good electronic device to place said known good device in a predetermined condition;

circulating a second sequence of data words, starting with a given data word, around a loop starting from the output of the known good unit and ending at the input thereof;

sampling said data word in a predetermined sequence of circulations of the data words;

storing the sampled data words;

initializing an electronic device to be tested to have the same predetermined condition as said known good device after initialization;

circulating a third sequence of data words, starting with said given data word, around said loop comprising said electronic device being tested;

sampling said third sequence of circulating data words in the same predetermined sequence of circulations as the known good unit was sampled; and

comparing the corresponding sampled circulating data words of the third sequence of circulating data words with the sampled stored data of said second sequence of said circulated data words to determine the identity of said data words being compared.

6. A method for testing electronic devices comprising the steps of:

initializing a known good electronic device of the type to be tested to a predetermined condition;

characterizing said known good unit to produce a sequence of data words of which every Nth data word is stored;

initializing an electronic device to be tested to produce said predetermined condition;

testing said electronic device to produce a second sequence of data words;

comparing for coincidence each successive Nth data word of said second sequence of data words with each successive data word of said stored Nth data words.

7. A method for testing electronic devices comprising the steps of:

initializing a known good electronic device of the type to be tested to a known, predetermined condition;

circulating for P circulations an initially determined data word through said known good electronic device and through a transfer function which, when in any given condition, will always alter any given data word in the same way;

sampling said circulating data word every Nth circulation thereof;

storing said sampled data words;

initializing an electronic device to be tested to said known, predetermined condition;

circulating for P circulations said initially determined data word through said electronic device being tested and through said transfer function;

sampling said circulating data word circulating through said electronic device being tested every Nth circulation thereof;

comparing for coincidence each successive sampled data word with the corresponding successive stored sampled data word.

8. A testing system for digitally testing electronic devices having an initialization mode of operation, a characterization mode of operation, and a testing mode of operation, and comprising;

first means for supplying a sequence of initializing instruction data words, and a sequence of initializing data words, and for receiving, storing, and supplying a sequence of sampled data words;

test station means for electrically connecting one of said electronic devices into said testing system;

transfer function means;

compare function means;

master control logic means, responsive to said initialization instruction data words, for supplying said initialization data words to said electronic device for initializing said electronic device to a given condition and for identifying the end of the initialization mode of operation;

said master control logic means further constructed to respond to the end of said initialization mode of operation to form a closed loop circuit cOmprising said electronic device and said transfer function means, to cause an initially determined data word to circulate in said closed loop circuit, and to sample said circulating data word every Nth circulation thereof;

said master control logic further comprising switching means having first and second states and constructed, when in a first state, to supply said sampled data words to said first means to be stored therein, and when in a second state to supply said sampled data words to said compare function means;

said first means further constructed to respond to the second state of said switching means of said master control logic to supply sequentially, and in the same order in which they were stored, the data words stored therein to said compare function means, with each Nth stored sampled data word being present in said compare function means during a time interval coincident with the presence in said compare function means of the Nth sampled data word of the circulating data word, where M represents any given time-corresponding sampling;

said compare function means constructed to compare the stored sampled data words and the sampled circulating data words supplied thereto for coincidence therebetween.

9. A testing system in accordance with claim 8 comprising in addition;

first storage means connected, during the initialization mode of operation, between the output of said data processor means and said electronic device; and

gating means responsive to the supplying of data words from said data processor means to become conductive to pass said data words into said first storage means; and

means for clocking said data words stored from said first storage means into said electronic device.

10. A testing system in accordance with claim 8 comprising;

first storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said transfer function means and the input of said electronic device;

second storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said electronic device and the input of said transfer function means;

said master control logic means comprising timing means;

gating means responsive to said timing means for progressively circulating a data word around the said closed loop circuit which comprises said second storage means, said transfer function means, said first storage means, and said electronic device.

11. A testing system in accordance with claim 8 in which;

said master control logic means and said first means are each constructed to respond to a comparison in said compare function means, of a sampled data word from said circulating sequence of data words and a stored sampled data word from said data processor before supplying another sampled data word to said compare function means.

12. The apparatus of claim 8 wherein the transfer function means includes means for randomizing the data word as it passes therethrough.

13. A testing system in accordance with claim 8 in which said master control logic means further comprises;

first storage means responsive to said instruction data words to store the number of initialization data words to be supplied from said data processor means during said initialization mode of operation and to decrement said stored number by a predetermined number each time an initialization data word is supplied from said data processor means;

counter means responsive to said instruction data words to become conditioned to count the number of data word circulations around said closed loop circuit between samplings and to indicate when such samplings are to be made; and

second storage means responsive to said instruction data words to store the number of samplings to be made during each of the characterization mode of operation and the testing mode of operation, and to decrement said Stored number each sampling of the data word during the characterization or testing modes of operation.

14. A testing system in accordance with claim 13 comprising in addition;

third storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said transfer function means and the input of said electronic device;

fourth storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said electronic device and the input of said transfer function means;

said master control logic means comprising timing means gating means responsive to said timing means for progressively circulating a data word around the said closed loop circuit which comprises said fourth storage means, said transfer function means, said third storage means, and said electronic device.

15. A testing system in accordance with claim 14 in which;

said third storage means comprises a plurality of fifth storage means, with each of said fifth storage means connected between the output of said transfer function and a different group of input terminals of said electronic device;

said fourth storage means comprises a plurality of sixth storage means with each of said sixth storage means being connected between a different group of output terminals of said electronic device and the input of said transfer function means;

said gating means comprises a plurality of gating means constructed to form a plurality of closed loop circuits with each closed loop circuit comprising said transfer function means, said electronic device and one each of said fifth and sixth plurality of storage means; and

in which said master control logic means comprises selecting means for successively selecting each of said closed loop circuits for circulating the data completely around each selected closed loop circuit before selecting and circulating the data around the next selected closed loop circuit.

16. A testing system in accordance with claim 15 comprising, in addition;

timing means constructed for circulating said data word around said closed loop circuit at selectable rates of speed.

17. A testing system in accordance with claim 14 in which;

said third storage means comprises a plurality of fifth storage means, with each of said fifth storage means connected between the output of said transfer function and a different group of input terminals of said electronic device;

said fourth storage means comprises a plurality of sixth storage means with each of said sixth storage means being connected between a different group of output terminals of said electronic device and the input of said transfer function means;

said gating means comprises a plurality of gating means constructed to form a plurality of closed loop circuits with each closed loop circuit comprising said transfer function means, said electronic device and one each of said fifth and sixth plurality of storage means; and

in which said master control logic means comprises selecting means for successively selecting each of said closed loop circuits and for circulating the data completely around each selected closed loop circuit before selecting and circulating the data around the next selected closed loop circuit.

18. A testing system in accordance with claim 13 comprising, in addition;

timing means constructed for circulating said data words around said closed loop circuit at selectable rates of speed.

19. A testing system for digitally testing electronic devices having initialization, characterization, and testing modes of operation and comprising;

data means for supplying a first sequence of instruction words to condition said testing system for a given initialization mode of operation and a given characterization or testing mode of operation and for supplying data words to initialize one of said electronic devices to a known condition;

transfer function means;

control means for circulating an initially determined data word around a closed loop circuit comprising said transfer function means and said electronic device;

means for sampling said circulating data word every Nth circulation thereof around said closed loop circuit;

compare function means;

means for selectively supplying said sampled data words to one of said compare function means and said data processor means;

said data processor means constructed to store said received sampled data words;

means for consecutively supplying said stored sampled data words to said compare function means in the same order in which they were received and stored and at times coincident with the supplying of corresponding currently sampled circulating data words to said compare function means;

said compare function means constructed to compare the stored sampled data words and the sampled circulating data words supplied thereto for coincidence;

means responsive to non-coincidence between a stored data word and a currently sampled circulating data word in said compare function means to supply an error signal to said data processor means.

20. A testing system in accordance with claim 19 in which;

said control means and said data means are each constructed to respond to a comparison, in said compare function means, of a sampled data word from said circulating sequence of data words and a stored sampled data word, before supplying another sampled data word to said compare function means.

21. The apparatus of claim 19 wherein the transfer function means includes means for randomizing the data word as it passes therethrough.

22. A testing system in accordance with claim 19 comprising:

first storage means connected, during the initialization mode of operation, between the output of said data means and said electronic device; and

gating means responsive to the supplying of data words from said data means to become conductive to pass said data words into said first storage means; and

means for clocking said data words stored from said first storage means into said electronic device.

23. A testing system in accordance with claim 19 comprising;

first storage means responsive to said instruction words to store a first given number of initialization data words to be supplied from said data means during said initialization mode of operation and to terminate the supplying of initialization data words when the given number of initialization data words have been supplied from said data means;

counter means responsive to said instruction words to become conditioned to count the number of data word circulations around said closed loop circuit between samplings and to indicate when such samplings are to be made; and

second storage means responsive to said instruction data words to store a second given number of samplings to be made during each of the characterization mode of operation and the testing mode of operation, and to terminate the present characterization or testing mode of operation when said second given number of samplings has occurred.

24. A testing system in accordance with claim 23 comprising;

third storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said transfer function means and the input of said electronic device;

fourth storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said electronic device and the input of said transfer function means;

timing means;

gating means responsive to said timing means for progressively circulating a data word around the said closed loop circuit which comprises said fourth storage means, said transfer function means, said third storage means, and said electronic device.

25. A testing system in accordance with claim 24 in which;

said third storage meAns comprises a plurality of fifth storage means, with each of said fifth storage means connected between the output of said transfer function means and a different group of input terminals of said electronic device;

said fourth storage means comprises a plurality of sixth storage means with each of said sixth storage means being connected between a different group of output terminals of said electronic device and the input of said transfer function means;

said gating means comprises a plurality of gates constructed to respond to said timing means to form a plurality of closed loop circuits, with each closed loop circuit comprising said transfer function means, said electronic device and one each of said fifth and sixth plurality of storage means; and

comprising selecting means for successively selecting each of said closed loop circuits and for circulating the data completely around each selected closed loop circuit before selecting and circulating the data around the next selected closed loop circuit.

26. A testing system in accordance with claim 19 comprising;

first storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said transfer function means and the input of said electronic device;

second storage means connected, during said characterization mode of operation and during said testing mode of operation, between the output of said electronic device and the input of said transfer function means;

timing means;

gating means responsive to said timing means for progressively circulating a data word around the said closed loop circuit which comprises said second storage means, said transfer function means, said first storage means, and said electronic device.

27. A testing system in accordance with claim 26 in which;

said timing means is constructed to circulate said data word around said closed loop circuit at selectable rates of speed.

28. A testing system in accordance with claim 26 in which;

said first storage means comprises a plurality of third storage means, with each of said third storage means connected between the output of said transfer function and a different group of input terminals of said electronic device;

said second storage means comprises a plurality of fourth storage means with each of said fourth storage means being connected between a different group of output terminals of said electronic device and the input of said transfer function means;

said gating means comprises a plurality of gates constructed to respond to said timing means to form a plurality of closed loop circuits, with each closed loop circuit comprising said transfer function means, said electronic device and one each of said third and fourth plurality of storage means; and

comprising selecting means for successively selecting each of said closed loop circuits and for circulating the data completely around each selected closed loop circuit before selecting and circulating the data around the next selected closed loop circuit.

29. A testing system in accordance with claim 28 in which;

said timing means is constructed to circulate said data word around said closed loop circuit at selectable rates of speed.

30. Apparatus for digitally testing electronic units comprising, in combination:

unit input and unit output means for connection to a unit to be tested;

first means for supplying initializing data words;

switching means connected to said unit input means, said unit output means and said first means for first supplying said initializing data words to a unit to be tested via said unit input means and for subsequently circulating data words from said unit output means to said unit input means;

second means for sampling said circulating data words at predetermined intervals;

storage means, connected to said second means, for storing the sampled data words obtained from testing a reference known good unit;

comparison means, connected to said storage means, and said second means, for comparing the stored sample data words from the reference known good unit with time corresponding sample data words from the unit being tested; and

apparatus output means for providing an indication of the comparison.

31. Apparatus for testing electronic devices comprising in combination:

first means for supplying a given sequence of initializing instruction data words and a sequence of initializing data words, and for receiving, storing, and supplying a sequence of sampled data words;

second means for comparing two inputs;

third means connected to said first means for initially causing said first means to supply said sequence of initializing instruction data words to a unit to be tested and then causing said first means to circulate the resulting data words in a closed loop circuit, said third means sampling the circulating data word at predetermined circulation intervals thereof, said third means being further connected to said second means for supplying sampled data words thereto indicative of signals obtained from a known good unit and supplying the sampled data words from the unit under test to said second means in the same order as originally obtained for comparison within said second means; and

output means for providing an indication of the comparison function.