US4010556A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic mathematics trainer
Assignee: CHURCHILL WAY PRESBYTERIAN CHURCH
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Filing: 1975-06-04
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Granted: 1977-03-08
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Expires: 1995-06-04
Abstract
Abstract The specification discloses an electronic mathematics trainer including a problem sheet bearing a plurality of arithmetic problems. An arithmetic problem display holder receives the problem sheet and includes lamps therein for sequentially being illuminated to indicate sequential ones of the arithmetic problems to be solved. A keyboard encoder enables a student to manually enter the arithmetic problem presently illuminated on the problem sheet. A display unit displays the arithmetic problem which is entered into the encoder. Circuitry is provided to compute the correct answer to the arithmetic problem entered into the encoder, along with at least one incorrect answer. The incorrect and correct answers are displayed on the display unit. Structure is provided to enable the selection of one of the displayed answers. If the correct answer is selected, the answer to the problem is then displayed adjacent the displayed problem. Circuitry in the display holder is responsive to the selection of the correct displayed answer in oder to advance the illumination of the lamps to the next arithmetic problem on the problem sheet. Selection of the correct displayed answer also clears the arithmetic problem displayed on the display unit.
Inventors
- 👤 Carolyn Ellsworth
- 👤 L. W. Herring
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:45
CPC Classifications
G; G09; G09B; G09B19/00; G09B19/02; G09B19/025; G09B5/00; G09B5/02; G09B7/00; G09B7/06
Claims Analysis
Total Claims: 73
Claim 1
Independent Claim
83 words
An electronic mathematics trainer comprising: means for selectively entering an arithmetic problem to be solved, means for computing the correct answer to the arithmetic problem, means for generating at least one incorrect answer to the arithmetic problem, means for displaying the correct and incorrect answers, means for randomly positioning the correct and incorrect answers on said display means, means operable for selecting one of the displayed answers, and means for clearing the entered arithmetic problem upon the selection of the correct displayed answer.
Claim 2
Dependent Claim
83 words
An electronic mathematics trainer comprising: means for selectively entering an arithmetic problem to be solved, means for computing the correct answer to the arithmetic problem, means for generating at least one incorrect answer to the arithmetic problem, means for displaying the correct and incorrect answers, means for randomly positioning the correct and incorrect answers on said display means, means operable for selecting one of the displayed answers, and means for clearing the entered arithmetic problem upon the selection of the correct displayed answer.
Claim 3
Dependent Claim
21 words
The electronic mathematics trainer of claim 1 and further comprising: a problem display wherein the unsolved entered arithmetic problem is displayed.
Claim 4
Dependent Claim
31 words
The electronic mathematics trainer of claim 2 and further comprising: means for retaining the display of the entered problem in said problem display until the selection of the correct displayed answer.
Claim 5
Dependent Claim
29 words
The electronic mathematics trainer of claim 2 and further comprising: means for entering the selected correct displayed answer in said problem display adjacent the displayed unsolved entered arithmetic problem.
Claim 6
Dependent Claim
24 words
The electronics mathematics trainer of claim 2 wherein said means for displaying answers and said problem display comprise a plurality of light emitting diodes.
Claim 7
Dependent Claim
24 words
The electronic mathematics trainer of claim 2 wherein said means for displaying answers and said problem display comprise a plurality of heat emitting elements.
Claim 8
Dependent Claim
43 words
The electronic mathematics trainer of claim 1 wherein said means for selectively entering an arithmetic problem to be solved includes a keyboard containing keys for the decimal numbers zero through nine and the four arithmetic operation modes of addition, subtraction, multiplication, and division.
Claim 9
Dependent Claim
35 words
The electronic mathematics trainer of claim 7 and further comprising: means for retaining the operation mode of the entered arithmetic problem after clearing the entered arithmetic problem upon the selection of the correct displayed answer.
Claim 10
Dependent Claim
25 words
The electronic mathematics trainer of claim 7 and further comprising: means for preventing the entering of more than one operation mode for an arithmetic problem.
Claim 11
Dependent Claim
31 words
The electronic mathematics trainer of claim 7 wherein said keyboard includes keys embossed with Braille alphabet characters or similar characters for indicating the function of said key to a sightless person.
Claim 12
Dependent Claim
26 words
The electronic mathematics trainer of claim 1 and further comprising: means for indicating whether the selected displayed answer is the correct answer or an incorrect answer.
Claim 13
Dependent Claim
71 words
The electronic mathematics trainer of claim 1 and further comprising: a problem list bearing a plurality of arithmetic problems, a problem list holder for receiving said problem list, means in said holder for sequentially indicating ones of the arithmetic problems to be selectively entered and solved, and means in said display holder responsive to the selection of the correct displayed answer for advancing said indicting means to a next arithmetic problem.
Claim 14
Dependent Claim
36 words
The electronic mathematics trainer of claim 1 and further comprising: means for accepting only valid arithmetic problems to be solved by said computing means, wherein said valid problems include only integer operations and positive signed numbers.
Claim 15
Dependent Claim
115 words
An electronic mathematics trainer comprising: means for selectively entering an arithmetic problem to be solved, a problem display for indicating the entered arithmetic problem, means for computing the correct answer to the entered arithmetic problem, means for generating at least one incorrect answer to the entered arithmetic problem, a solution display for indicating the correct and incorrect answers, means for randomly positioning the correct and incorrect answers in said solution display, means operable for selecting one of the displayed answers, means for indicating the selection of a correct displayed answer, means for indicating the selection of an incorrect displayed answer, and means for clearing the entered arithmetic problem upon selection of the correct displayed answer.
Claim 16
Dependent Claim
115 words
An electronic mathematics trainer comprising: means for selectively entering an arithmetic problem to be solved, a problem display for indicating the entered arithmetic problem, means for computing the correct answer to the entered arithmetic problem, means for generating at least one incorrect answer to the entered arithmetic problem, a solution display for indicating the correct and incorrect answers, means for randomly positioning the correct and incorrect answers in said solution display, means operable for selecting one of the displayed answers, means for indicating the selection of a correct displayed answer, means for indicating the selection of an incorrect displayed answer, and means for clearing the entered arithmetic problem upon selection of the correct displayed answer.
Claim 17
Dependent Claim
36 words
The electronic mathematics trainer of claim 14 and further comprising: means for accepting only valid arithmetic problems to be solved by said computing means, wherein said valid problems include only integer operations and positive signed numbers.
Claim 18
Dependent Claim
29 words
The electronic mathematics trainer of claim 14 and further comprising: means for displaying the selected correct displayed answer in the proper place in the format of the displayed problem.
Claim 19
Dependent Claim
42 words
The electronic mathematics trainer of claim 14 and further comprising: means for retaining the operation mode of an entered arithmetic problem upon selection of the correct displayed answer and subsequent to operation of said clearing means to clear the entered arithmetic problem.
Claim 20
Dependent Claim
40 words
The electronic mathematics trainer of claim 14 wherein said means for selecting one of the displayed answers includes a plurality of answer selection keys located so that each of said keys is adjacent a displayed answer in said solution display.
Claim 21
Dependent Claim
22 words
The electronic mathematics trainer of claim 14 wherein said solution display and said problem display include a plurality of light emitting diodes.
Claim 22
Dependent Claim
22 words
The electronic mathematics trainer of claim 14 wherein said solution display and said problem display include a plurality of heat emitting elements.
Claim 23
Dependent Claim
39 words
The electronic mathematics trainer of claim 14 wherein said means for selectively entering an arithmetic problem includes a keyboard containing keys for the decimal numbers zero through nine and the four arithmetic operations of addition, subtraction, multiplication, and division.
Claim 24
Dependent Claim
33 words
The electronic mathematics trainer of claim 21 wherein said keyboard includes keys with raised characters of the Braille alphabet or similar characters for indicating the function of said keyboard to a sightless person.
Claim 25
Dependent Claim
30 words
The electronic mathematics trainer of claim 14 wherein said means for indicating the selection of an incorrect displayed answer include means for blanking said solution display of the incorrect answer.
Claim 26
Dependent Claim
170 words
An electronic mathematics trainer comprising: a problem sheet bearing a plurality of arithmetic problems, an arithmetic problem display holder for receiving said problem sheet, means in said display holder for sequentially indicating ones of the arithmetic problems on said problem sheet to be solved, a keyboard encoder for entering the arithmetic problem indicated on said display holder, a display unit for displaying the arithmethic problem entered in said encoder, means for computing a correct answer to the arithmetic problem entered by said keyboard encoder, means for generating at least one incorrect answer to the arithmetic problem entered by said keyboard encoder, means on said display unit for randomly displaying the correct and incorrect answer, means operable for selecting one of the displayed answers, means in said display holder responsive to the selection of the correct displayed answer for advancing said indicating means to a next arithmetic problem on said problem sheet, and means for clearing the arithmetic problem displayed by said display unit upon selection of the correct displayed answer.
Claim 27
Dependent Claim
170 words
An electronic mathematics trainer comprising: a problem sheet bearing a plurality of arithmetic problems, an arithmetic problem display holder for receiving said problem sheet, means in said display holder for sequentially indicating ones of the arithmetic problems on said problem sheet to be solved, a keyboard encoder for entering the arithmetic problem indicated on said display holder, a display unit for displaying the arithmethic problem entered in said encoder, means for computing a correct answer to the arithmetic problem entered by said keyboard encoder, means for generating at least one incorrect answer to the arithmetic problem entered by said keyboard encoder, means on said display unit for randomly displaying the correct and incorrect answer, means operable for selecting one of the displayed answers, means in said display holder responsive to the selection of the correct displayed answer for advancing said indicating means to a next arithmetic problem on said problem sheet, and means for clearing the arithmetic problem displayed by said display unit upon selection of the correct displayed answer.
Claim 28
Dependent Claim
32 words
The electronic mathematics trainer of claim 24 wherein said display unit includes means for entering the correct answer in the display of the arithmetic problem upon selection of the correct displayed answer.
Claim 29
Dependent Claim
33 words
The electronic mathematics trainer of claim 24 and further comprising: means for retaining the arithmetic operation of an entered arithmetic problem after said means for clearing the arithmetic problem clears the arithmetic problem.
Claim 30
Dependent Claim
20 words
The electronic mathematics trainer of claim 24 and further comprising: means for indicating the selection of the correct displayed answer.
Claim 31
Dependent Claim
20 words
The electronic mathematics trainer of claim 24 and further comprising: means for indicating the selection of an incorrect displayed answer.
Claim 32
Dependent Claim
36 words
The electronic mathematics trainer of claim 24 and further comprising: means in said display holder for retaining said problem sheet until the selection of the correct displayed answer for all the problems on said problem sheet.
Claim 33
Dependent Claim
17 words
The electronic mathematics trainer of claim 24 wherein said display unit comprises a plurality of light-emitting diodes.
Claim 34
Dependent Claim
18 words
The electronic mathematics trainer of claim 24 wherein said display unit comprises a plurality of heat emitting elements.
Claim 35
Dependent Claim
32 words
The electronic mathematics trainer of claim 24 wherein said keyboard encoder comprises keys containing raised Braille alphabet characters or similar means for indicating the functions of said keys to a sightless person.
Claim 36
Dependent Claim
220 words
An electronic mathematics trainer comprising: a problem sheet bearing a plurality of arithmetic problems to be entered into said keyboard encoder, a problem sheet holder for receiving said problem sheet, means in said holder for sequentially indicating an arithmetic problem on said problem sheet, a student operated keyboard encoder for selectively entering the decimal numbers and arithmetic operation mode of an arithmetic problem on said problem sheet to be solved, a problem display from displaying the entered arithmetic problem, means for computing the correct answer, means for generating at least one incorrect answer, a solution display for displaying the correct and incorrect answers, means for randomly positioning the correct and incorrect answers in said solution display, means operable for selecting one of the displayed answers, means for indicating the selection of a correct answer, means for indicating the selection of an incorrect answer, means for displaying the selected correct answer on said problem display, means in said holder responsive to the selection of the correct displayed answer for advancing said indicating means to a next problem, means for retaining said problem sheet in said holder until the correct displayed answer has been selected for all problems on said problem sheet, and means operable for clearing the arithmetic problem entered by said keyboard encoder upon selection of the correct displayed answer.
Claim 37
Dependent Claim
220 words
An electronic mathematics trainer comprising: a problem sheet bearing a plurality of arithmetic problems to be entered into said keyboard encoder, a problem sheet holder for receiving said problem sheet, means in said holder for sequentially indicating an arithmetic problem on said problem sheet, a student operated keyboard encoder for selectively entering the decimal numbers and arithmetic operation mode of an arithmetic problem on said problem sheet to be solved, a problem display from displaying the entered arithmetic problem, means for computing the correct answer, means for generating at least one incorrect answer, a solution display for displaying the correct and incorrect answers, means for randomly positioning the correct and incorrect answers in said solution display, means operable for selecting one of the displayed answers, means for indicating the selection of a correct answer, means for indicating the selection of an incorrect answer, means for displaying the selected correct answer on said problem display, means in said holder responsive to the selection of the correct displayed answer for advancing said indicating means to a next problem, means for retaining said problem sheet in said holder until the correct displayed answer has been selected for all problems on said problem sheet, and means operable for clearing the arithmetic problem entered by said keyboard encoder upon selection of the correct displayed answer.
Claim 38
Dependent Claim
33 words
The electronic mathematics trainer of claim 33 and further comprising: means for accepting only valid arithmetic problems for said computing means, wherein said valid problems include only integer operations and positive signed numbers.
Claim 39
Dependent Claim
21 words
The electronic mathematics trainer of claim 33 wherein said solution display includes means for simultaneously displaying the correct and incorrect answers.
Claim 40
Dependent Claim
41 words
The electronic mathematics trainer of claim 33 and further comprising: a plurality of momentary pushbuttons with one of said pushbuttons adjacent each of the displayed answers to provide said means for indicating the selection of the correct or an incorrect answer.
Claim 41
Dependent Claim
32 words
The electronic mathematics trainer of claim 33 and further comprising: means for retaining the entered arithmetic operation mode upon operating the means for clearing the arithmetic problem entered by said keyboard encoder.
Claim 42
Dependent Claim
28 words
The electronic mathematics trainer of claim 33 and further comprising means for correcting an erroneous entry of a decimal number or an arithmetic operation of an arithmetic problem.
Claim 43
Dependent Claim
103 words
The electronic mathematics trainer of claim 33 wherein said keyboard encoder includes means for a sightless person to enter the decimal numbers and arithmetic operation mode of an arithmetic problem to be solved, wherein said solution display includes means for enabling a sightless person to detect the display of correct and incorrect answers, wherein said problem and display includes means for enabling a sightless person to determine the entered arithmetic problem, and wherein said means for indicating the selection of a correct or an incorrect answer includes means for enabling a sightless person to determine whether the selected answer is correct or incorrect.
Claim 44
Independent Claim
93 words
A method of teaching arithmetic skills, comprising the steps of: displaying a plurality of arithmetic problems to be solved, entering the decimal numbers and the arithmetic operation mode of one of the arithmetic problems into an electronic mathematics trainer, displaying the entered arithmetic problem without an answer to the student, computing a correct answer and at least one incorrect answer, randomly displaying the correct answer and at least one incorrect answer, selecting one of said answers, and displaying the correct answer together with the entered problem upon the selection of a correct answer.
Claim 45
Independent Claim
93 words
A method of teaching arithmetic skills, comprising the steps of: displaying a plurality of arithmetic problems to be solved, entering the decimal numbers and the arithmetic operation mode of one of the arithmetic problems into an electronic mathematics trainer, displaying the entered arithmetic problem without an answer to the student, computing a correct answer and at least one incorrect answer, randomly displaying the correct answer and at least one incorrect answer, selecting one of said answers, and displaying the correct answer together with the entered problem upon the selection of a correct answer.
Claim 46
Dependent Claim
25 words
The method of teaching arithmetic skills of claim 40 and further comprising the step of: indicating to a student when an incorrect answer is selected.
Claim 47
Dependent Claim
25 words
The method of teaching arithmetic skills of claim 40 and further comprising the step of: indicating to a student when a correct answer is selected.
Claim 48
Dependent Claim
43 words
The method of teaching arithmetic skills of claim 40 and further comprising the step of: identifying in sequence one of the plurality of displayed arithmetic problems upon each selection of a correct displayed answer for entering into the electronic mathematics trainer for solution.
Claim 49
Dependent Claim
45 words
The method of teaching arithmetic skills of claim 43 and further comprising the step of: retaining the display of a plurality of arithmetic problems for use in the electronic mathematics trainer until a correct displayed answer has been selected for all the displayed arithmetic problems.
Claim 50
Dependent Claim
84 words
In a mathematics training system, the combination comprising: means for selectively entering an arithmetic problem to be solved, means for computing the correct answer for the problem to be solved, means for computing at least one incorrect answer for the problem to be solved, an answer display having at least two display positions, and means for randomly controlling the display of said correct and incorrect answers on said answer display, such that said correct answer may be displayed on any of said display positions.
Claim 51
Dependent Claim
84 words
In a mathematics training system, the combination comprising: means for selectively entering an arithmetic problem to be solved, means for computing the correct answer for the problem to be solved, means for computing at least one incorrect answer for the problem to be solved, an answer display having at least two display positions, and means for randomly controlling the display of said correct and incorrect answers on said answer display, such that said correct answer may be displayed on any of said display positions.
Claim 52
Dependent Claim
21 words
The combination of claim 45 wherein two incorrect answers are generated and further comprising: three display positions in said answer display.
Claim 53
Dependent Claim
102 words
The combination of claim 45 and further comprising: a plurality of two position electronic switches for controlling the operation of said display positions. a pulsed shift register for continuously outputting a sequence of digital signals each corresponding to a distinct display position for determining the location of said correct answer, a position selector switch for receiving the continuous output of digital signals from said shift register and for controlling the output of said electronic switches, and a data control switch for randomly stopping said shift register, the output of said register determining the location of said correct answer in said display positions.
Claim 54
Dependent Claim
38 words
The combination of claim 45 and further comprising: a plurality of switches corresponding to each of the data display positions for selecting an answer, and means for blanking the display position displaying an incorrect answer upon its selection.
Claim 55
Dependent Claim
13 words
The combination of claim 46 wherein said two positions electronic switches comprise multivibrators.
Claim 56
Dependent Claim
106 words
The combination of claim 46 and further comprising: a problem display for formatting an arithmetic problem, means for generating digital clock signals, a plurality of data selectors composing an electronic switch continuously rotated through all of the switch positions by said digital clock signals, thereby enabling the problem to be solved to said problem display and the correct and incorrect answers to be displayed in said answer display, means for detecting the operation mode of the training system, and at least one operation selector switch responsive to said detecting means for selectively routing the problem to be solved on the correct answer to said data selectors.
Claim 57
Dependent Claim
23 words
The combination of claim 45 and further comprising: means for suppressing the display of leading zeros in answers displayed by said answer display.
Claim 58
Dependent Claim
220 words
The combination of claim 45 wherein said means for computing in incorrect answer comprises: a free running oscillator, a plurality of incorrect answer shift registers clocked by said oscillator, means for generating digital clock signals, a decade counter pulsed by said digital clock signals, a control shift register responsive to the computation of a correct answer by the trainer, a ring counter operated by said control shifter for enabling successive ones of said incorrect answer shift registers to load data from said decade counter, a plurality of exclusive OR gates, a plurality of data selectors for loading the output from said incorrect answer shift registers to one side of said OR gate upon said data selectors being enabled by said ring counter, a correct answer selector for loading the correct answer on the other side of said OR gate, means for loading a next number into the enabled one of said incorrect answer shift registers from said decade counter upon said OR gates indicating the correct answer and the output of said incorrect answer shift register are the same, and means for advancing said control shift register to the next one of said incorrect answer shift registers upon said OR gate detecting that the correct answer differs from the output of the enabled one of said incorrect answer shift registers.
Claim 59
Dependent Claim
50 words
The electronic circuit of claim 52 and further comprising: a two position electronic control switch for applying a clock pulse to the plurality of said incorrect answer shift registers upon said OR gates first detecting a difference between the output of said incorrect answer shift registers and the correct answer.
Claim 60
Dependent Claim
85 words
In a mathematics training system, the combination comprising: means for selectively entering an arithmetic problem to be solved, means for computing the correct answer for a problem to be solved, means for randomly generating a sequence of numbers, means for comparing the correct answer to the randomly generated numbers, means for selecting a randomly generated number determined by said comparing means to be different from the correct answer, and means for displaying the correct answer and a randomly generated number determined by said selecting means.
Claim 61
Dependent Claim
85 words
In a mathematics training system, the combination comprising: means for selectively entering an arithmetic problem to be solved, means for computing the correct answer for a problem to be solved, means for randomly generating a sequence of numbers, means for comparing the correct answer to the randomly generated numbers, means for selecting a randomly generated number determined by said comparing means to be different from the correct answer, and means for displaying the correct answer and a randomly generated number determined by said selecting means.
Claim 62
Dependent Claim
38 words
The combination of claim 54 wherein said selecting means operates only upon the second number determined by said comparing means to be different from the correct answer, thereby preventing the same randomly generating numbers from being repeatedly selected.
Claim 63
Dependent Claim
99 words
An electronic mathematics trainer comprising: means for automatically generating a random arithmetic problem; means for automatically entering the randomly generated arithmetic problem, a display unit for displaying the arithmetic problem automatically entered, means for computing a correct answer to the automatically entered arithmetic problem, means for generating at least one incorrect answer to the automatically entered arithmetic problem, means on said display unit for randomly displaying the correct and incorrect answer, means operable for selecting one of the displayed answers, and means for clearing the arithmetic problem displayed by said display unit on selection of the correct displayed answer.
Claim 64
Dependent Claim
99 words
An electronic mathematics trainer comprising: means for automatically generating a random arithmetic problem; means for automatically entering the randomly generated arithmetic problem, a display unit for displaying the arithmetic problem automatically entered, means for computing a correct answer to the automatically entered arithmetic problem, means for generating at least one incorrect answer to the automatically entered arithmetic problem, means on said display unit for randomly displaying the correct and incorrect answer, means operable for selecting one of the displayed answers, and means for clearing the arithmetic problem displayed by said display unit on selection of the correct displayed answer.
Claim 65
Dependent Claim
32 words
The electronic mathematics trainer of claim 56 wherein said display unit includes means for entering the correct answer in the display of the arithmetic problem upon selection of the correct displayed answer.
Claim 66
Dependent Claim
20 words
The electronic mathematics trainer of claim 56 and further comprising: means for indicating the selection of the correct displayed answer.
Claim 67
Dependent Claim
20 words
The electronic mathematics trainer of claim 56 and further comprising: means for indicating the selection of an incorrect displayed answer.
Claim 68
Dependent Claim
23 words
The electronic mathematics trainer of claim 56 and further comprising: means for selecting the arithmetic operation for the automatically generated random arithmetic problem.
Claim 69
Dependent Claim
26 words
The electronic mathematics trainer of claim 56 and further comprising: means for selecting random generation of the operation mode of the automatically randomly generated arithmetic problem.
Claim 70
Independent Claim
91 words
A method of teaching arithmetic skills, comprising the steps of: automatically generating a random arithmetic problem to be solved, automatically entering the decimal numbers and arithmetic operation mode of the generated arithmetic problem into an electronic mathematics trainer, displaying the entered arithmetic problem without an answer to the student, computing a correct answer and at least one incorrect answer, randomly displaying the correct answer and at least one incorrect answer, selecting one of said answers, and displaying the correct answer with the entered problem upon the selection of a correct answer.
Claim 71
Independent Claim
91 words
A method of teaching arithmetic skills, comprising the steps of: automatically generating a random arithmetic problem to be solved, automatically entering the decimal numbers and arithmetic operation mode of the generated arithmetic problem into an electronic mathematics trainer, displaying the entered arithmetic problem without an answer to the student, computing a correct answer and at least one incorrect answer, randomly displaying the correct answer and at least one incorrect answer, selecting one of said answers, and displaying the correct answer with the entered problem upon the selection of a correct answer.
Claim 72
Dependent Claim
25 words
The method of teaching arithmetic skills of claim 62 and further comprising the step of: indicating to a student when an incorrect answer is selected.
Claim 73
Dependent Claim
25 words
The method of teaching arithmetic skills of claim 62 and further comprising the step of: indicating to a student when a correct answer is selected.
References Cited (Backward Citations)
US3153863A
Cited
US3144720A
Cited
US3231693A
Cited
US3300875A
Cited
US3477142A
Cited
US3631459A
Cited
US3584398A
Cited
US3851745A
Cited
US3894346A
Cited
US3796037A
Cited
US3787988A
Cited
US3925909A
Cited
USPTO Annuity & Maintenance Windows
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|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-07 | 1980-09-06 | 1981-03-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-07 | 1984-09-06 | 1985-03-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-07 | 1988-09-06 | 1989-03-08 | $7700.00 | Window Closed / Lapsed |