US2812907A - Interest-computing device - Google Patents

Description

Nov. 12, 1957 S. H. KANTROWITZ INTEREST-COMPUTING DEVICE Firm April 28, 1954 FIG JUN JULY Nov] m MAR APR MAY AUG SEPT OCT milzismsmwmmm nuuumi m$mssm$$m mlmssitmmfimHHzHl mmmmmszmmmms mmasimmmflmsmm smmwMHHHMHI umnsmmmmamm;

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IN V EN TOR.

ATTORNEY United States Patent INTEREST-COMPUTING DEVICE Sidney H. Kantrowitz, Teaneck, N. J.

Application April 28, 1954, Serial No. 426,112 11 Claims. (Cl. 235-89) The present invention relates to calculators, and particularly to computing devices by which interest and dividend factors per dollar of a principal sum may be obtained for a period of time designated in conventional calendar notations.

Calculators are known for obtaining interest factors for a period of time designated as a given number of days, months and years. An interest or dividend payment is then computed by multiplying the obtained interest factor times the principal amount. These known devices exhibit a number of drawbacks, prominently the need for the operator to compute time independently and before ascertaining the interest factor through use of the device. Stated differently, the operator must transpose a time period expressed by a period-start date having a day,

month and year notation, and a period-end date, likewise having a day, month and year notation, to a definite number of years, months and days. Further, devices requiring a transposition to a given number of years, months and days for the period under consideration, frequently produce three separate subfactors, a first corresponding to the number of years, a second to the number of months, and a third to the number of days. These subfactors must be added to obtain the interest factor. Still further, some of these known devices utilize the concept of obtaining factors for ones, tens, hundreds and thousands designations of a principal sum and performing additional arithmetic operations to arrive at the final interest or principal payment.

It is an object of the present invention to provide an improved interest and dividend computing device obviating one ormore of the aforesaid difiiculties. Specifically, it is within the contemplation of the present invention to provide computing devices by which interest factors may be obtained without the need for preliminary breaking down of a time period into its corresponding numbers of years, months and days.

It is a further object of the present invention to provide a computing device for ascertaining interest or dividend factors for a period of time, such that a final interest or dividend payment for said period may be ascertained by merely multiplying the interest factor times the principal sum.

It is a still further object of the present invention to provide an interest-computing device which is inherently simple, and may be used with standard oflice computing equipment to arrive at interest and dividend factors for principal sums. Advantageously, by simple manual manipulation, an operator can obtain an interest factor for a period of time and use a computing machine to arrive at the final interest or dividend payment for said period, with extreme accuracy and minimum expenditure of time and effort.

In accordance with an illustrative embodiment demonstrating features and aspects of the present invention, an interst-computing device is initially set up for computing interest or dividend factors at a given interest or dividend rate. The device includes a chart holder havinga chartframing opening, and an interest factor chart at said given interest rate having first and second sets of interest factor columns, with the columns of each set having day-by-day interest factors for a period of one month. The columns of the first set are laterally offset by one column relative to the columns of the second set, such that sequential reading from month to month throughout the chart may be accomplished. Means are associated with the chart and holder for establishing period-start notations and period-end notations, each expressed as a month and day, with appropriate provision for reading the interest factor for the period covered by said notations.

The facility in operation, as well as further objects, features and advantages of the present invention, will be best appreciated by reference to the following detailed description of a presently preferred embodiment, when taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a plan view, approximately to size and with portions folded back for clarity, showing an interest computing device embodying features of the present invention;

Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1 and looking in the direction of the arrows;

Fig. 3 is a fragmentary plan view showing the arrangement of the month selector on the front face of the chart holder; and

Fig. 4 is a plan view of a 6% interest factor chart illustrating features of the present invention.

Specific reference will now be made to the drawings, wherein there is shown an interest computing chart in ac- 'cordance with the present invention which includes a chart holder or body 10 and interest computing charts 12 contained therein. Although only one interest computing chart is shown in the illustrative embodiment, it is to be appreciated that a set of charts or cards would be provided with each chart holder, each chart being set up for computing interest factors at a particular rate of interest.

The chart holder 10 includes front and rear rectangular walls 14, 16 which are spaced apart and substantially coextensive in size. The walls or panels 14, 16 made of any suitable paper or plastic material, are arranged to define a longitudinally extending channel or guideway 18 therebetween for accommodating therein one or more of the interest factor charts 12. In the illustrative form of the invention, the panels 14, 16 are joined by an upper end wall 20 and one side wall 22. The panel may be joined by side walls such that charts are inserted from either open end.

The front wall or panel 14 of the chart holder or body 10, is formed with a chart-framing opening or field 24. The size of the rectangular chart-framing opening is selected in accordance with the column arrangement of the interest computing chart 12. The width of the opening 24 corresponds to twelve column widths, while the height of the opening 24 depends upon the vertical spacing of the interest factors in the respective columns, and is such that thirty vertically-disposed factors may be framed therein.

A period-start column 26 is arranged along the left vertical side edge of the chart-framing opening 24 and includes consecutive numbers from one to thirty corresponding to the days of the month. The numbers of the period-start column are arranged in an increasing series reading downwardly along the vertical side edge of the chart-framing opening 24 and serves as references in selecting interest factors, as will subsequently be described.

Slidably mounted on the chart holder or body 10 is a month selector slide 28 which is in the form of a sleeve and has a transversely or horizontally extending window 30 in the front wall thereof. The window 30 is arranged to selectively frame rows of a month selector chart'32, illustrated in Fig. 3. The month selector chart 32 includes month designations or indicia on the front panel 14 of the body at locations spaced above the chart-framing opening. The selector 32 is oriented in relation to the respective vertical columns framed by the opening 24 and include twelve horizontal rows of month designations. Each of the rows, when selected, provides month headings for the vertical columns of the interest factor chart. The successive rows of the month selector 32 begin with successive months of the year, such Lhat headings may be provided for the columns starting from any given month of the year and reading from left to right. For example, in the slide position illustrated in Fig. 1, the window frames the sixth horizontal row of the indicia 32 and gives month headings for the chart columns beginning from the month of June and reading consecutively to the month of May, from left to right. a

Reference will now be made to Fig. 4, wherein there is shown the details of a chart 12 having day by day 6% interest factors. The chart 12 includes a datum or reference line 34 extending horizontally of the chart and dividing the chart 12 into an upper-half section 12a and a lower-half section 1212. In the upper-half section 12a is a first set of interest factor columns which extend above the datum line 34, and in the lower half section 1217 is a second set of interest factor columns extending below the datum line. The interest factor columns in each of the sets or half-sections of the chart have day by day interest factors which are disposed in sequence for reading up successive columns of the respective sets. For example, the right margin column A of the lower half section 12b has interest factors beginning from the smallest factor of .00017, corresponding to the single day factor at 6%, and increasing by day increments to the uppermost factor of .00483. The next factor in sequence corresponds to the interest factor for one month or thirty days, namely .005 or one-half of one percent, and lies along the datum or reference line 34.

The columns of the respective interest factor sets are laterally offset by one column such that an aligned pair of columns composed of one from each set have interest factors disposed in sequence when reading up the aligned pairs of columns. As an example, interest factor column A at the right-hand margin of the lower-half section 12b, is identical to column A at the left hand margin of the upper-half section 12a. It will be appreciated that the columns A and A correspond to interest factors for a first thirty day period or the first month. Identical columns corresponding to a second thirty day period or the second month are respectively designated by the letters B and B. The column'B is next adjacent to the column A in the lower-half section 12b of the chart 12, while its identical column B is next adjacent to column A in the upper-half section 12a. The laterally offset column arrangement is such that reading up the columns A, B interest factors may be read in sequence for a period of two months. The symmetry of the chart, and the arrangement of the remainder of the columns should be apparent by visual inspection and from the foregoing description.

Along one side of the 6% interest chart 12 is a periodend column 36 which has consecutive numbers corresponding to the days of the month, as in the period-start column 26. The numbers of the period-end column 36 are arranged in an increasing series reading upwardly from the vicinity of the datum line 34 such that any day in a period end notation may be selected.

In the front panel or wall 14 of the chart holder 10, there is formed a window 38 for selectively framing the numbers or indicia of the period-end column 36. The window 38 is oriented in relation to the beginning of the period-start column 26 as the period-end column 36 is oriented relative to the datum or reference line 34. Specifically, the window 38 is opposite the period-start designation 3, whereas the period-end column 36 is disposed such that the designation 3 is directly along the datum line 34.

The function of the illustrated device will be best appreciated by considering a typical problem. If, for example, the interest factor at 6% from a period-start date of February 12 of a given year through a periodend date of June 27 of said given year is to be obtained, the following manipulations are performed.

The month selector slide 28 is vertically displaced in relation to the chart body 10 such that the window 30 frames the sixth row of the month-heading indicator 32, that is the row beginning with the month heading June. Thus, the headings for the factor chart columns will begin with June, the month of the period-end notation, reading from left to right. The 6% chart is vertically displaced within the guide or channelway 18 until the day of the month that the interest is to be computed to appears in the window 38. After this sliding movement, the chart 12 is in relation to the chart-forming opening 24 such that the respective interst factor columns have the required month headings or designations which are visually observed through the window 30. As shown in Figs. 1 and 3, the interest chart is set for computing interest from the period-end date of June 27 of a given year, to any period-start date within that year. In the selected example, the period-start date is February l2'and accordingly, the operator looks down the columns of the framed portion of the interest chart headed by the month designation February. In this column, the operator selects the interest factor appearing opposite the day designated 12 in the period-start column 26, as indicated by arrows, and reads the interest factor .0225. This factor indicates the interest at 6% for the stated period based upon the principal sum of $1.00. Thereupon, it is merely necessary to multiply the dollars and cents of a given principal sum by this factor to arrive at an interest or dividend payment.

For determining discounts, it will be appreciated that the outlined procedure is reversed, that is the month designation to which the discount is to be computed is set in the window 30 of the month selector slide 28, and the day designation is arranged to appear in window 38 of the chart body 10.

As a further feature of the invention, the chart body 10 is provided with indicia facilitating use of the chart when the number of days in a period is known. For this purpose along the lower horizontal edge of the chart framing window 24, there is provided designations or headings for successive thirty day periods, arranged from right to left along the twelve columns of the chart-framing opening 24. When the number of days is known or is easily ascertainable, it is merely necessary to slide the interest-computing chart 12 to a longitudinal position wherein the number appearing in window 38 corresponds to the number of days in excess of multiples of thirty for the period. The interest factors for this number of days is read in the last visible line of the chart, corresponding to the horizontal line opposite numeral 30 of the period-start column 26 and underlined by the lower horizontal edge of the opening 24. Specifically, the chart in Figs. 1 and 3 is set to read an interest factor for twenty-seven days, or factor twenty-seven days in excess of multiples of thirty. For. example, reading in the horizontal line opposite the numeral 30, the interest factor for twenty-seven days is .0045; further, for two hundred and seven days, the interest factor is .0345. As previously stated, these factors may be used with any principal sums for interest and dividend calculations.

It will be appreciated that greater accuracy may be obtained by extending the accuracy of the interest factors [11 the chart to more than five places.

The many advantages and facility of the present interestcomputing device should be apparent from the foregoing description. The device is characterized in that the period-start and period-end designations are expressed in conventional day and month notation, and may be used as a basis for computing an interest factor for a given period without the need for transposition to a given number of days and months. The thus obtained interest factor is but a single number and in turn may be multiplied with any principal sum or amount to ascertain interest or dividend. Further applications of the device will be apparent to those acquainted with the business fields and numerous applications are to be found in banking, discount and installment credit operations.

Numerous modifications of the device of the present invention will occur to those skilled in the art, and accordingly the appended claims should be given a latitude of interpretation consistent with the disclosure and at times certain features of the invention will be used without a corresponding use of other features.

What I claim is:

1. An interest computing device comprising a chart holder, at least one chart having first and second sets of interest factor columns, the columns of each set having day by day interest factors for a period of one month with the columns of said first set being laterally offset relative to the columns of said second set whereby an aligned pair of columns has consecutive day by day interest factors, a period-start column on said chart holder having consecutive numbers corresponding to the days of the month, a period-end column on said chart having consecutive numbers corresponding to the days of the month, and period-end day selector means on said chart holder disposed in predetermined relation to said periodstart and period-end columns.

2. An interest computing device comprising a chart holder having a chart-framing opening, at least one chart having first and second sets of interest factor columns one of which extends above a datum line and the other of which extends below said datum line, the columns of each set having day by day interest factors for a period of one month with the columns of said first set being laterally offset by one column relative to the columns of said second set, a period-start column on said chart holder having consecutive numbers corresponding to the days of the month, a period-end column on said chart in predetermined relation to said datum line and having consecutive numbers corresponding to the days of the month, and a period-end day selector window on said chart holder in predetermined relation to said period-start column.

3. An interest computing device comprising a chart holder having a chart-framing opening, a chart having first and second sets of interest factor columns one of which extends above a datum line and the other of which extends below said datum line, the columns of each set having day by day interest factors for a period of one month, the columns of said first set being laterally offset by one column relative to the columns of said second set whereby consecutive interest factors may be read in an aligned column pair, a period-start column on said chart holder having consecutive numbers corresponding to the days of the month, a period-end column on said chart having consecutive numbers corresponding to the days of the month, and a period-end day selector window in said chart holder disposed in predetermined relation to said period-start and period-end columns, said period-end column having its numbers arranged in an increasing series extending upwardly from said datum line in parallel relation to said interest factor columns.

4. An interest computing device comprising a chart holder including a chart-framing opening having an upper edge, at least one chart having first and second sets of interest factor columns one of which extends above a datum line and the other of which extends below said datum line, the columns of each set having day by day interest factors for a period of one month with the columns of said first set being laterally offset by one column relative to the columns of said second set, a period-start column on said chart holder having consecutive numbers corresponding to the days of the month, a period-end column on said chart having consecutive numbers corresponding to the days of the month, and a period-end day selector window in said chart holder disposed in predetermined relation to said period-start and period-end columns, said period-start column having its numbers arranged in an increasing series extending downwardly from said upper edge of said chart-framing opening, and said period-end column having its numbers arranged in an increasing series extending upwardly from said datum line.

5. An interest computing device comprising a chart holder having a chart-framing opening, and at least one chart having a datum line, a first set of interest factor columns extending below said datum line, a second set of interest factor columns extending above said datum line, the interest factor columns of each of said sets having day by day interest factors which are disposed in sequence for reading up successive columns of the respective sets, the columns of said sets being laterally offset by one column whereby an aligned pair of columns composed of one from each set have interest factors disposed in sequence for reading up the aligned pair.

6. An interest computing device comprising a chart holder having a chart-framing opening, and at least one chart having a datum line, a first set of interest factor columns extending. below said datum line, a second set of interest factor. columns extending above said datum line, the interest factor columns of each said sets having day by day interest factors which are disposed in sequence for reading up successive columns of the respective sets, the columns of said sets being laterally offset by one column whereby an aligned pair of columns composed of one from each set have interest factors disposed in sequence for reading up the aligned pair, a period-start column on said chart holder having consecutive numbers corresponding to the days of the month, the numbers of said period-start column being arranged in an increasing series reading downwardly along one side of said chartframing opening, and a period-end column on said chart having consecutive numbers corresponding to the days of the month, the numbers of said period-end column being arranged in an increasing series reading upwardly from said datum line.

7. In an interest computing device, a chart having a datum line, a first set of interest factor columns extending below said datum line, a second set of interest factor columns extending above said datum line, the interest factor columns of each of said sets having day by day interest factors which are disposed in sequence for reading up successive columns of the respective sets, the columns of said sets being laterally offset by one column whereby an aligned pair of columns composed of one from each set have interest factors disposed in sequence for reading up the aligned pair.

8. An interest computing device comprising a chart holder having a chart-framing opening, and at least one chart having a datum line slidably supported in said chart holder, a first set of interest factor columns extending below said datum line, a second set of interest factor columns extending above said datum line, the interest factor columns of each of said sets having day by day interest factors which are disposed in sequence for reading up successive columns of the respective sets, the columns of said sets being laterally offset by one column whereby an aligned pair of columns composed of one from each set have interest factors disposed in sequence for reading up the aligned pair, a period-start column on said chart holder having consecutive numbers correspond- A r a 7 r ing to the days of the month, the numbers of said periodstart column being arranged in an increasing series reading downwardly along one side of said chart-framing open ing, and a period-end column on said chart having consecutive numbers corresponding to the days of the month, the numbers of said period end column being arranged in an increasing series reading upwardly from said datum line, and a period-end selector window on said chart holder for selectively framing a number of said periodend column in response to slidable displacement of said chart relative to said chart holder.

9. A device for reading an interest factor for a time interval from period-start to period-end dates comprising a chart holder having a chart-framing opening, and at least one chart having a datum line, a first set of interest factor columns extendingbelow said datum line, a sec ond set of interest factor columns extending above said datum line, the interest factor columns of each of said sets having day by day interest factors which are disposed in sequence for reading up successive columns of the respective sets, the columns of said sets being laterally offset by one column whereby an aligned pair of columns composed of one from each set have interest factors disposed in sequence for reading up the aligned pair, a periodstart column on said chart holder having consecutive numbers corresponding to the days of the month, the numbers of said period-start column being arranged in an increasing series reading downwardly along one side of said chart-framing opening, and a period-end column on said chart having consecutive numbers corresponding to the days of the month, the numbers of said periodend column being arranged in an increasing series reading upwardly in relation to said datum line, and a month selector selectively oriented in relation to said chart to provide the month designation for the period-end date and for the period-start date.

10. A device for reading an interest factor for a time interval designated by period-start and period-end dates comprising a chart holder having a chart-framing opening, at least one chart having a datum line, a first set of month by month interest factor columns extending below said datum line, a second set of month by month interest factor columns extending above said datum line, the interest factor columns of each of said sets having day by day interest factors for successive months which are disposed in sequence for reading up successive col umns of the respective sets, the columns of said sets bein laterally offset by one column whereb an aligned pair of columns composed stone from each set have interest factors disposed in sequence for reading up the aligned pair, means for orienting said chart in relation to said chart holder for a'selee'ted period-end date, and means for locating the interest'factor on said chart at a location corresponding to said period-start date.

ll. A device for reading an interest factor for a time period designated by period start and end dates comprising a chart holder having a chart-framing opening, and at least one chart, a first set of interest factor columns, a second set of interest factor columns, the interest factor columns of each of's'aid sets having day by day interest factors which are disposed in sequence for read ing up successive columns of the respective sets, the columns of said sets being laterally oifset by one column whereby an aligned pair of columns composed of one from each set have interest factors disposed in sequence for reading up the aligned pair, a period-start column on said chart holder having consecutive numbers corresponding to the days of the month, the numbers of said periodstart column being arranged in an increasing series reading downwardly along one side of said chart-framing opening, and a period-end column on said chart having consecutive numbers corresponding to the days of the month, the numbers of said period-end column being arranged in an increasing series reading in a direction opposite to said period-start column, a month selector for providing month headings for said columns and settable in relation to said chart for providing month headings starting with the month designation of the period-end date, and a period-end selector window in said chart holder for selectively framing a number of said periodend column in response to slidable displacement of said chart relative to said chart holder.

References Cited in the file of this patent UNITED STATES PATENTS 294,079 Robinson Feb. 26, 1884 778,790 Merrill Dec. 27, 1904 1,162,828 Ammerstol Dec. 7, 1915

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