Perpetual recording calendar

A perpetual calendar 1 which is set by folding back portions at the right and left sides of a month panel 2. Day-of-the-week designators 7 appear on a separate heading panel 3 above the seven displayed columns of date boxes 9. The user makes event entries 8 in the date box 9 marked with the appropriate date number 10. The date for each, month has thirteen columns of date boxes 9 marked with a redundantly extended array of date numbers 10. Date numbers 10 on each month panel 2 begin at the top of the middle column. The month panel 2 is folded back on scored lines between the columns so that only the appropriate seven columns are displayed. Hidden behind the heading panel 3 are year number markings 21 indicating the creases for each year. The month panel 2 for each month is identified by a month label 18 placed at the bottom of the center column so as to always be displayed. Because of redundancy in the date number array, event entries 8 must be duplicated unless they fall in the center column.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a perpetual calendar, and more specifically to a 
perpetual calendar which accommodates permanent notes for birthdays and 
other anniversaries on a conventional full-month display. 
2. Description of Related Art 
Many perpetual calendars have been developed which display the days of each 
month in seven columns corresponding to the days of a week. They all 
depend on the finite number of combinations that occur; a month can only 
start on one of seven days and have one of four lengths: 28, 29, 30 or 31 
days. Many of the existing designs employ lists or look-up tables to 
identify which of 7 to 28 displays to use for a given month and year. 
Others have a date panel with a redundantly extended array, in which dates 
are repeated in thirteen or more columns, behind a mask which is aligned 
to show the correct seven columns. These "slide calendars" may be set to a 
code from a look-up table or by alignment of month and year on scales 
which appear on the mask and movable date panel. 
The mathematics behind look-up tables or slide calendar scales are straight 
forward: A normal year of 365 days contains 52 weeks plus one day. 
Consequently each month will begin one day later in the following year. In 
leap years (years evenly divisible by 4) February has 29 days, causing 
March and subsequent months to start two days later than in the previous 
year. A 28-year repeat cycle occurs; 21 regular years at 1 day plus 7 leap 
years at 2 days equals 35 days or 7 weeks. Because years divisible by 100 
are not leap years unless they are divisible by 400, three out of four 
centuries have 76 regular years and 24 leap years; 76+24.times.2=124 days, 
2 days short of 18 weeks. Thus each century the first-day-of-the-month 
pattern moves two days earlier. The one-day shift for the leap century 
brings the total to 7 days, making each of these four-century periods 
identical. 
SUMMARY OF THE INVENTION 
The primary objective of the present invention is to provide a continuing 
reminder of annual events, such as birthdays and other anniversaries. By 
displaying them on a conventional monthly calendar, they will come to the 
user's attention much more frequently than occurs with date books 
currently available for this purpose. By folding back the columns of the 
date panel that would conventionally be obscured by a mask, the date boxes 
can be made large enough to accommodate notes. Because all dates except 
those in the center column appear redundantly, most events must be entered 
in two boxes. Once this is done the notes will be displayed year after 
year on an up-to-date monthly calendar. Day-of-the-week column headings 
are placed on separate panel, aligned to the displayed month panel. This 
tabular display concept can be used for data elements other than date 
numbers. The familiar Gregorian calendar is the example used for the 
preferred embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
As shown in FIG. 1, the perpetual anniversary calendar 1 has the appearance 
of the calendars widely used to record appointments and other reminders. 
An array of date boxes 9 are marked with date numbers 10 and appear in 
columns under day-of-the-week designators 7. Unlike a conventional 
calendar, this calendar 1 can be used year after year with the entered 
notes 8 reappearing on an up-to-date display of the month. As depicted in 
FIG. 1, the calendar 1 comprises a number of monthly date panels 2 
overlaid with a heading panel 3. The heading panel 3 extends beyond the 
area of the date panel 2 marked with date boxes 9 and is marked with day 
of the week designators 7. This heading panel 3 can also carry any desired 
message or decoration. The back flap 4 of the heading panel 3 acts to keep 
the heading panel 3 positioned at the top of the month panel 2. 
For display purposes, the current month panel 2 of the perpetual calendar 1 
is placed into a picture frame (not shown) or other container having a 
transparent front surface. This protects the calendar 1 and also permits 
it to be used as a conventional appointment calendar, entries being made 
on the outside of the container with a washable marker. Month panels 2 not 
being displayed can be stored elsewhere or placed behind the front month 
panel 2. 
As illustrated by examples in script font, the user writes name, year and 
other pertinent event information 8 in the date box 9 marked with the 
relevant date number 10. In addition to date boxes 9 for each day of the 
particular month, there are supplemental date boxes 11 for several days at 
the beginning of the following month. Also entry annex boxes 12, 
identified with index letters 13, are provided in which to make overflow 
entries 14 which cannot be fit into the relevant date box 9. These 
overflow entries 14 are keyed to the date by reference letters 15 written 
into the date boxes 9. 
A representative date panel 2, shown unfolded in FIG. 2, has thirteen 
columns 16 and six rows 17. Date numbering 10 begins at the top of the 
center column 16g in the top row 17a and progresses to the right. Date 
numbering 10 in the second row 17b begins with the number two resulting in 
the number eight appearing below number one in the center column 16g. The 
remainder of this redundantly extended array is filled such that each date 
box 9 contains a date number 10 increased by seven from the date number 10 
above it. The month of March, used for the example in FIG. 1, has 31 days. 
Accordingly,supplemental date boxes 11 to the right of the two date boxes 
9 marked with 31 as the date number 10 contain smaller size supplemental 
date numbers 10a from 1 to 4, corresponding to the first four days of the 
following month, April. 
No date box is placed at the bottom of the center column 16g providing 
space for an abbreviated month label 18. In this position the month label 
18 remains visible as the display changes for months starting on different 
days of the week. The remaining twelve boxes, six at the left side of the 
top row 17a and six at the right side of the bottom row 17f are entry 
annex boxes 12 marked with index letters 13 A through F, so that overflow 
entries 14 can be keyed to date boxes 9. When written into a date box 9, 
the index letter 15 alerts the user to the presence of additional 
information for that date. With the exception of date numbers 10 that fall 
into the center column 16g, there are two date boxes 9 for each date 
number 10. This requires duplicate entries as illustrated in FIG. 2 by 
paired data entries 8a, 8b. The exception is illustrated by a center 
column 16g event entry 8c for March 29th. 
To facilitate the folding that results in a non-redundant display, a date 
panel 2 made of paper should have creases 20 along the fold lines between 
the columns 16. At the top of the date panel 2 each crease 20 is marked 
with year numbers 21 indicating the years for which the date panel 2 is 
folded back at that crease 20. For one 28-year cycle each crease 20 is 
used four times. The year numbers 21 appear sequentially, moving from 
right to left along six rows. The seven creases 20a in the left half of 
the date panel 2 have an array of year numbers 21 identical to that 
appearing at the seven creases 20b in the right half of the date panel 2. 
February, having twenty eight days in normal years and twenty nine in leap 
years, requires special treatment. FIG. 3 illustrates how this is 
accommodated by use of a contrasting font (underlined characters in the 
example) for date numbers 10 that differ in leap years. These leap year 
numbers 22 are placed in the supplemental date boxes 11 to the right of 
the date box 9 having 28 as its date number 10 and in the supplemental 
date boxes 11 at the left side of the bottom row 17f. In the supplemental 
date boxes 11 for February the small leap year numbers 22a serve to inform 
the user that event entries 8 made for the normal supplemental date 
numbers 10a are delayed (moved to the right) by one day in leap years. 
For normal years, when February is exactly four weeks long, its date panel 
2 is folded the same as the one for March. For leap years the additional 
day causes the folds to be displaced one column 16 to the right. Thus in 
FIG. 2 the sequence of year numbers 21 on the creases 20 for March 
advances two columns 16 at each leap year and for February this two-column 
advance occurs for the years following leap years as shown in FIG. 3. 
Date panels 2 for the other months are of the same form. Provided the date 
boxes 9 are printed in close registration, the date panels 2 for the 12 
months can be printed on six sheets, using both sides. 
The two arrays of year numbers 21 on the creases 20 must be shifted to 
produce the other six phasings of date numbers 10 relative to 
day-of-the-week designators 7. These alignment shifts for the year number 
21 arrays are illustrated by the single-panel calendar shown in FIG. 4. 
Because the setting table 23 for the calendar in this example has only a 
single row of year numbers 24 for each row of month indicators 25 the 
range of settings only covers five or six years. 
To accommodate months of different length on a single date panel 2 the date 
numbers at the end of the month 27, 28, 29 are marked using distinctive 
fonts, the same fonts being used for the month indicators 25 and year 
indicators 24 in the setting table 23. In the example, month and year 
indicators 25a for 31-day months and the date number 31 27 are in bold 
italics, the date number 28 28 and month indicators for February 25b and 
are in normal font, date number 29 29 and leap years in the February year 
number row 25b are underlined, and month and year indicators for 30-day 
months 25c are in normal bold font. 
By folding the panel 2 back on the column divider lines 20 marked for a 
specific month-year combination, a seven column calendar is formed. 
Subsequently folding again along the horizontal crease 26 results in a 
compact calendar display 30. It can be combined with a title panel 31 
marked with the designators for the days of the week 7 and inserted into a 
transparent case 32 with both the date numbers 10 and the table of month 
and year indicators 23 visible as shown in FIGS. 5 and 6. The back side of 
the title card 31 includes definitions 33 for the distinctive fonts 27,28 
and 29. Additional operating instructions can be placed on the back of the 
title card 31 in the space covered by the folded month panel 2. The front 
of the title card 31 has space for an advertising message or business card 
imprint. 
The preferred embodiments described above and represented in the drawings 
constitute a practical and familiar applications of the invention. The 
claims which follow are intended to include other calendar formats and any 
sequential set of numbers, characters or icons for which a 
phase-adjustable display is desired.