Perpetual Calendar

This invention relates to a calendar of the "perpetual" type, which comprises a number of cubes, the faces of which are provided with indicia representative of components of the date. By adjusting the orientation of the cubes relative to each other, the faces displayed to an observer are changed so as to adjust the day, month and year displayed on a day-by-day basis.

Examples of such perpetual calendars are disclosed in FR-A-2419553, FR-A-1174184 and US―A―3853741.

The pre-characterising clause of claim 1 is based on FR-A-2419553, which is considered to be the closest prior art.

The prior calendar includes a group of two numbered cubes dedicated exclusively to the days of the month, a further group of two numbered cubes dedicated to the last two digits of the year, and another group of three lettered cubes dedicated to the months of the year.

Such a prior calendar possesses a number of disadvantages. In particular, it has a maximum continuous range of only 32 years. Furthermore, since the groups of three cubes display an abbreviated form of the month in letters of the alphabet, the calendar is not internationally understandable, and is not in an internationally acceptable format. Moreover, the abbreviations are not those usually employed by native French speakers.

It is an object of the present invention to provide a perpetual calendar which overcomes the aforesaid disadvantages.

The perpetual calendar according to the invention is defined in the characterising clause of claim 1. In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which:-

• Fig. 1 to 6 show various alternative preferred sets of cubes for use in calendars embodying the invention;
• Fig. 7 shows one particular form of a display device having cubes located therein forming a calendar embodying the invention;
• Fig. 8 is an enlarged view of a single cube of the type shown in the display device of Fig. 7, and a portion of the device;
• Fig. 9 shows a particular form of arrangement by means of which the cubes can be locked into the display device;
• Fig. 10 shows, in a descriptive manner, various configurations which could be adopted in a display device;
• Fig. 11 shows a front view of a production form of the device in which the cubes are held in a different manner; and
• Fig. 12 is an end elevation of the device of Fig. 11.

Before describing the particular perpetual calendars illustrated in the drawings, I will provide a more general description of the calendar and the components thereof, with specific reference to various embodiments.

I have referred herein to a set of cubes, and the word cube is used in the mathematical sense of being three dimensional, and the actual components may physically be solid or may be hollow.

For example, the cubes could be made of two or more components, say by injection or extrusion moulding of plastics material, and these components could be fitted together, either by physical interengagement of components or by an adhesive or welding to form the final cubes.

Further, the cubes do not have to be of strict geometric form, and they can, for example be formed with curved corners.

The faces of these cubes bear indicia, as will be described further hereinafter, and, if required, these could be embossed into or extend outwardly in relief from the faces of the cubes. In particular, each face of each cube bears a single numeric index selected from the numerals 0 to 9, although, optionally, one or more faces of the cubes may be blank.

Where numerals are to be displayed, it will be appreciated that cubes do not have sufficient faces for a full set of numerals to be on each cube and, as such, the number of possible number sets is restricted because of this. In order to cover a maximum range of dates to be displayed, it is necessary to be strictly selective as to the actual allocation of numerals to the faces of the cubes.

In one particular required form, the calendar comprises a set of eight cubes, all of which cubes are used at all times. The faces of all eight cubes are displayed at any one time, with the first two indicating the day, the second two the month and the last four the year. Obviously there are constraints generally on dates, which are, for example, in the Gregorian calendar, the days never go beyond 31; the months never beyond 12; and the first two digits of the year will, in the reasonably foreseeable future, be only 1 or 2. Other calendars have other constraints.

It will be appreciated that a "perpetual" calendar must represent a large number of consecutive dates. If there is a break, or even one missed date, this must be deemed to be the end of the effective life of the calendar. The main problem with a calendar made of cubes with no spares is the distribution of numbers between the cubes.

A set of calendar cubes represents, besides many short sequences, the longest possible sequence-or- run of successive dates around a time. The run cannot be extended backwards (but with the finish data the same) by changing any of the cubes' faces. The forty-eight indicia to be distributed on a set are unique to a particular run, through more than one distribution of those forty-eight indica will give the same run. No other forty-eight indica have the same finish and start dates, given the same conventions. (An example of these conventions is given below.) From the definition of a set of calendar cubes, it is clear that no indicia appears more than once on the same cube.

Preferred sets of calendar cubes are shown in Figs. 1 to 6.

□ represents a blank face. Two conventions used in arriving at these sets are that a single face is used for 6 and 9 and that 0 may only be used before and 0 after 1,2,3,4, 5, 6, 7, 8, or 9 in the "Day", "Month" or "Year" section.

Thus, October 2nd, 2047 is represented by . At the top of each of these figures is shown the run expressible by the forty-eight indicia below. Each column represents one cube.

The particular indicia shown on each cube will give the run noted, as will some redistributions of the indicia within the set. Specifically excluded sets are shown beneath each array.

Rules for redistribution are as follows:-El and all numbers with a square border, e.g. , are specific to, i.e. fixed on that particular cube.

Numbers without a border, e.g. 2, may change places with any other borderless number if they are not separated by a vertical line.

Where numerals are shown in circles and have an arrow extending therefrom, an undetermined number of that particular value can move from the section to be exchanged with a numeral from the section where the arrowhead terminates.

Thus, in Fig. 2, for example, the numeral 4, from either the sixth, seventh or eighth cube can be exchanged with any of the numerals on the fifth cube.

The arrangement may be such as to enable a pattern to be established to change from one required display to the next.

Referring to Figs. 7 and 8, these show one particular form of display device adapted to be used with cubes of this embodiment of the invention.

It will be see that, in these cases, the cubes 80 each have an extension 71 which are of a size to be received in apertures 82 in the face of the display device 70.

The display device which is a holder is divided into three sections, the two upper sections each containing two cubes are being labelled "Day" and "Month" respectively and the third section containing four cubes and being labelled "Year".

Within the body of the holder there may be shelves or the like adapted to receive the cubes 80 at the correct height so that the extensions 71 can pass through the apertures 82.

When it is necessary to change the date, it is only necessary to initially remove the cubes that need to be changed from the holder and, if these cannot be turned to provide the numerals or blanks required, then they may be interchanged with other cubes which can show the desired faces. This takes no more than a few seconds.

In the version of Fig. 9, each cube 90 is provided with small apertures 93 in the centre of each face and a pin or the like 94 is adapted to pass through the wall of the holder 92 to retain the cube against movement, and also to prevent ready pilfering. The existence of the aperture 93 does not detract from the appearance of the face 91 which is outwardly directed.

In this arrangement, before the cubes are changed, the pins 94 have to be withdrawn to permit removal of the cubes.

Fig. 10 shows several different formats of a display which relocate the various components of Fig. 7 within the holder and, in each case, the day and month are clearly marked by lettering on the holder and, if required, the year can be so marked.

Figs. 11 and 12 show one particular practical form of device.

There is a body member 100 which, as illustrated, may be made from a single piece of material, such as a substantially rectangular block of wood or which could be moulded from a synthetic plastics material or which could be otherwise fabricated.

The body member 100 has eight cube receiving recesses 101, each of which is to receive one of the cubes 102 of the device for at least a substantial part of its depth. This can well be seen on Fig. 12.

In the embodiment the body member 100 is shown connected to a backing plate 103 which has a face 104 which could carry, for example, details of what is displayed by the cubes, or advertising material.

This member 104 could be provided with means whereby the device can be attached to a surface.

The actual mode of holding the cubes into display devices can vary greatly depending upon the particular form of cube and the required form of display device.

For example, the cubes could be held magnetically or the device could be provided with a hingedly or slideably mounted member which can be moved to permit the cube to be located and then closed to permit inadvertent removal, or there may be recesses or similar formations into which the cube can be located.

Whilst, the calendar herein described is primarily intended to be used as such, i.e. to display dates, it could alternatively be used for amusement purposes, as a puzzle, or as an educational device.