Patent Publication Number: US-5289649-A

Title: Perpetual calendar

Description:
This is a continuation of copending U.S. patent application Ser. No. 07/556,749 filed on Jul. 23, 1990, now abandoned. 
    
    
     This invention relates to a perpetual calendar, and more particularly a pocket calendar which uses a rotating disk to get the calendar of a month and year desired for a period extending over more than 5,000 years. 
     BACKGROUND OF THE INVENTION 
     Perpetual calendars existing until now either work only for a limited number of years, or require complicated instructions for their use. Instructions for using these calendars usually require various manual operations or mathematical computations to arrive at the month and year desired. 
     Accordingly, an object of the present invention is to provide a perpetual calendar which works for over 5,000 years. 
     Another object of the invention is to provide a perpetual calendar which is pocket-sized, so that it can be easily carried. 
     A further object of the invention is to provide a perpetual calendar which is easy to use with respect to manual and mathematical operations. 
     Another object of the invention is to provide a perpetual calendar by which one can determine the day of the week and month of a particular year quickly. 
     Still another object of the invention is to provide a perpetual calendar which can be printed on various materials and in various colors and designs to accommodate the needs of those who distribute them or use them for advertisement. 
     SUMMARY OF THE INVENTION 
     To achieve the foregoing and other objects of this invention there is provided a perpetual calendar from which for any desired year over a span of more than 5,000 years a monthly calendar can be obtained. 
     A key is provided on the back of a base member from which one obtains the indicia of the desired year. The year indicia is any numeral between and including &#34;0&#34; and &#34;6.&#34; The key consists of three matrix-type tables. One obtains the desired year indicia by following instructions given to reach a cross point of the tables. The tables are constructed based on certain mathematical calculations. 
     A top member has two arcuate window openings. Through one window the year indicia can be read. Along this window the months are listed in columns in a radial fashion so as to align with a corresponding year indicia. There are seven columns, each containing from one to three months. The months are deliberately grouped in such a way as to provide the appropriate monthly calendars desired. 
     Through the other window the days of the month can be read. The numbers range from one to thirty-one to correspond to the maximum number of days in any particular month. The numbers are arranged in a radial fashion, yet give the appearance of a curved monthly calendar in which the days of the week and month are read from left to right. There are seven columns here as well, each corresponding to the days of the week, Monday through Sunday. 
     The days of the week are placed on the top member, outside of and along the widest part of the arcuate window opening. Each week day aligns with a column of days seen through the window. 
     In operation, once the year indicia is derived from the key, one turns over the calendar and places the year indicia over the month desired. This is done by a simple circular motion of a disk member placed in between the top and base members. Once the year indicia and the month are aligned, the correct monthly calendar will automatically appear through and along the other window opening. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a top view of an embodiment of the present invention; 
     FIG. 2 a representation of the arcuate window openings with the days and months along the openings as they are in FIG. 1; 
     FIG. 3 is a view of the rotating disk member which is in between the top and base members; and 
     FIG. 4 is a partial view of the base member containing key indicia matrix tables representing the key indicia from which a desired year indicia is derived. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1 and 2, there is provided a top member (FIG. 1), which has two windows 1. The windows allow one to see the days of the month 2 and the indicia 3 that correspond to the desired year. Over the top window the seven days of the week 4 are printed. Below the lower window are printed the months of the year 5. 
     Referring to FIG. 3, a disk 6 is shown that rotates on its own axis. The disk 6 is attached to the top member (FIG. 1) with a metallic eyelet 7. The disk 6 is printed with the days of the month 8 and the year indicia 9. 
     Referring to FIG. 4, tables &#34;A&#34; 10 and &#34;B&#34; 11 printed on a base member (FIG. 4) are illustrated. By using the tables 10 and 11, one finds the year indicia 3 corresponding to the desired year by using the year indicia matrix 12. One can also find a desired Julian year from the Julian year table 13 or Gregorian year from the Gregorian year table 14. 
     The calendar can be used for 5,811 years, from 1512 B.C. to 4299 A.C. For the Julian style, it can be used up to 1799 A.C. For the Gregorian style, it can be used from 1500 A.C. to 4299. The calendar can be expanded indefinitely by placing the first two numbers of the desired year in the rows corresponding to the Gregorian style 14. 
     The empty spaces on the top member (FIG. 1) can be used to print messages for advertisements and the like. 
     The perpetual calendar is operated by turning the disk 6 until the year indicia 3 corresponding to the desired year matches the month 5 desired. For leap years, one must match the year indicia with the &#34;January&#34; or &#34;February&#34; printed in red and in parentheses in the months 5, if January and/or February are the particular months desired for a leap year. It will be understood by one skilled in the art that these leap year months can be designated by other methods without departing from the spirit of the invention. 
     The year indicia 3 corresponding to the user&#39;s desired year is found in the cross point in the year indicia matrix 12 of the column of table B 11 that contains the first two numbers of the year with the row of table A 10 that contains the last two numbers of the year. For the years before Christ, to 1513 deduct the year wanted and with the remaining proceed as if the year was of the Julian style. 
     By way of example, the year indicia for 1990 is 0. To arrive at this, one finds the number &#34;19&#34; in the Gregorian section of table B 11. Then one finds the number &#34;90&#34; in table A 10. The cross point of the column in which &#34;19&#34; is found in table B 11 and the row in which &#34;90&#34; is found in table A 10 is the number &#34;0&#34; found in the year indicia matrix 12. 
     From the foregoing description, those skilled in the art will appreciate that all the objectives of the present invention are realized. A perpetual calendar had been provided which is pocket-sized and can be used quickly to achieve a monthly calendar for a particular month and year chosen from more than a 5,000 year span. 
     While specific embodiments have been shown and described, many variations are possible. The particular design and style of the top, disk and base members, as well as the key matrix, days of the months and week, months and the year indicia, may vary without departing from the spirit of the invention. 
     Having described the invention in detail, those skilled in the art will appreciate that modifications may be made to the invention without departing from its spirit. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described. Rather, it is intended that the scope of this invention be determined by the appended claims and their equivalents.