Lunar clock

Abstract

 The present invention relates to a lunar clock capable of mimicking the illumination of the moon as it passes through the phases of the lunar cycle.

Description

[0001] The present invention relates to a lunar clock capable of mimicking the illumination of the moon as it passes through the phases of the lunar cycle.

[0002] The Moon has a significant physical influence on life on our planet due to its large size and its close proximity. At full moon it can reflect sufficient sunlight to light up the night. Its mass is great enough to distort the Earths shape and to produce tides in oceans and lakes. It also provides the main force that moves the poles of the Earth in the precession of the equinoxes. Its shadow on the earth at occasional times and places may obscure light from the Sun to produce solar eclipses. Though these influences on Earth may be subject to simple laws of physics and dynamics, we are only just beginning to understand how the Moon may influence the biology of life on our planet.

[0003] The calendar month is equivalent approximately to the period of revolution of the Moon around the Earth. This period (29 days 12 hours 44 minutes 2.8 seconds) is the synodic month and represents the time it takes for the Moon to pass through the sequence of phases from new to first quarter to full to third quarter to new again and make a complete revolution about the Earth with respect to the Sun.

[0004] The relative positions of the Sun, Earth and Moon affect the illuminated lunar image that is seen by an observer. The "New" phase occurs when the moon surface is in full shade and all three bodies are linearly aligned with the Moon positioned centrally. The phase "First Quarter" occurs when the half moon surface is in sunlight forming a semi-circular shape. This occurs as the moon revolves around the Earth with the Sun Earth Moon angle describing an approximate right angle. The phase "Full" occurs when the observed surface of the moon is fully illuminated by the Sun and again all bodies are linearly aligned but with the Earth centrally positioned. The phase "Third or last quarter" relates to a "half moon" but this time the moon position is between the new moon and full moon (i.e. approximately one hundred and eighty degrees removed from the first quarter). The left hand side of the Moon is illuminated as observed from Earth whereas it is the right hand side which is illuminated at the first quarter. In between these points, the shape of the moon appears as illuminated crescents or is gibbous and various angles of tilt can be observed.

[0005] Conventional moon dials (as used on various moon-phase clocks and watches) may comprise a single disc printed with two circular moon shapes positioned at 180 degrees to one another rotating behind a shaped window whose shape masks the visible or partly visible moon as it rotates to give an impression of the lunar phase. The window shape is similar to an axehead positioned with the crescent "cutting edge" uppermost and semicircular convex and concave sides which represent shadow as the moon disc rotates clockwise west to east. A disadvantage of this mechanism is that, as the moon goes from the third quarter to full phase, the shape of the shadow does not accurately represent the shadow which is observed on a near spherical object such as the Moon. As the Moon is gibbous and approaches fullness the pattern of the illuminated Moon produced by this mechanism is still crescent-like whereas it is the shadow which should be crescent shaped. Similarly, as the full Moon phase ages further, the initial shadow effect produced by the Eastern semicircular edge of the window is incorrect in that the appearance of the Moon should only become crescent shaped after the shadow covers more than half of the visible surface of the moon.

[0006] A moon phase dial mechanism is described in EP-A-869411. This device mimics the lunar cycle using overlapping, rotatable discs with appropriate shading.

[0007] A further mechanism utilises a rotating globe, half of which is painted white and the other half black. As this rotates, an accurate impression of the lunar cycle is displayed but the size of the sphere is a significant disadvantage.

[0008] In a further device, the various phases of the moon are separately displayed around the circumference of a clock and a pointer indicates the particular phase at a given time. Since many separate moons have to be represented on the same dial, the size of this clock is disadvantageous.

[0009] The present invention seeks to overcome certain disadvantages of the prior art by providing an improved lunar clock which mimics the phases of the moon in the lunar cycle.

[0010] Thus viewed from one aspect the present invention provides a lunar clock capable of mimicking the phases of the moon in at least a part of the lunar cycle, said clock comprising:

a lunar image means capable of exhibiting in an unmasked portion an image of the illuminated part of the moon in a phase in the lunar cycle and in a masked portion an image of the non-illuminated part of the moon at that phase in the lunar cycle;

masking means for partially and variably masking the lunar image means to define the masked and unmasked portions thereof;

drive means for imparting relative cyclical movement to the lunar image means and masking means through positions which mimic each phase in the lunar cycle or a part thereof.

[0011] The clock may mimic a part or the whole of the lunar cycle. Preferably the clock mimics the whole lunar cycle.

[0012] In a preferred embodiment, the lunar image means comprises a substantially flat, disc-shaped member. Preferably the disc-shaped member is substantially circular.

[0013] Preferably, the lunar image means is made from transparent material such as glass or perspex which may be patterned. For example, patterns representing lunar craters may be etched, sandblasted or printed on the surface of the lunar image means.

[0014] The masking means may take the form of a substantially flat screen with an elongate aperture. The shape of the aperture will be compatible with the chosen size and shape of the lunar image means. The lunar image means may be conveniently mounted to the rear or front of the flat screen.

[0015] Where the lunar image means is mounted to the rear of the screen, the unmasked portion of the lunar image means is visible through the aperture and the masked portion of the lunar image means is hidden behind the surface of the screen in order to simulate a phase in the lunar cycle.

[0016] Alternatively, where a transparent lunar image means is mounted to the front of the screen, light passing through the aperture in the screen and through the lunar image means defines the unmasked portion thereof and light prevented from passing through the lunar image means by the screen defines the masked portion thereof in order to simulate a phase in the lunar cycle.

[0017] Preferably the elongate aperture is a wave-like aperture. In a particularly preferred embodiment, the wave-like aperture comprises a substantially S-shaped aperture. This would normally be used with a lunar image means in the form of a disc-shaped member. Preferably the substantially S-shaped aperture has rotational symmetry. Particularly preferably, the tips of the S lie in a common, substantially vertical plane with the middle of the S having a lateral width which is the maximum lateral width of the aperture and which is approximately equivalent to the diameter of the lunar image means.

[0018] In an alternative embodiment, the aperture of the flat screen may take the form of approximately half of a substantially S-shaped aperture in a horn-like configuration. In this case, once the full moon is simulated, the clock may be rotated through 180° by the drive means and the direction of movement of the lunar image means is effectively reversed. The action is repeated every half a lunar cycle.

[0019] In another embodiment, the masking means may take the form of a ring so that the ends of a wavelike aperture may be joined. This enables the lunar image means to be rotated continuously and uni-directionally by the drive means.

[0020] The elongate aperture may be fronted by a white, silver or transparent material which may be back lit by a fixed illuminating means (eg a light source). The illuminating means may be fixed to the rear of the screen. Preferably, it is fixed to part of the lunar image means. This advantageously ensures that the lunar image means is selectively illuminated as it moves relative to the masking means. To heighten the contrast between the masked and unmasked portions of the lunar image means, the surface of the masking means is generally of a contrasting colour to the lunar image means (eg black or dark blue) to simulate the night sky.

[0021] In order to effect relative cyclical movement of the lunar image means and the masking means, the lunar image means may be movably attached to the rear of the screen whereby the drive means causes the lunar image means to traverse the path of the aperture (eg the wave-like aperture). Various drive means familiar to those skilled in the art may be adopted for this purpose (eg a suitable motor, gears and tooth belt). In general, the lunar image means is driven by the drive means so that its movement complements the shape of the aperture. For example, for a wave-like aperture the movement is complementarily, substantially wave-like. To ensure that the lunar image means is driven by the drive means so that its movement complements the shape of the aperture, the lunar clock may be provided with a guiding means such as an elongate passage or flange.

[0022] In one embodiment, the rear of the flat screen is fitted with two substantially parallel and substantially vertically mounted guide rods. These may be conveniently located outside the maximum lateral extent of the aperture, preferably at the outer edges of the rear of the screen. A substantially horizontal bar may be loosely coupled to the pair of guide rods at each end by coupling means so as to move vertically thereon and permit vertical movement of the horizontal bar across the rear of the face of the screen. Preferably the horizontal bar is provided with a free sliding sleeve. The sleeve is adapted so as to be attached to the rear of the lunar image means (eg disc). For example, the sleeve may be provided with an integral perpendicular rod attached to the rear of the lunar image means. The perpendicular rod may be dependent from about the central point of the sleeve (ie to form a substantially T-shaped arrangement).

[0023] The horizontal rod may be driven up and down the guide rods by means of an appropriate drive means eg motor, gears or tooth belt. The speed of movement is such to allow the lunar image means to traverse positions which mimic the phases of the moon in at least a part of the lunar cycle.

[0024] Where the lunar image means is located at the front of the screen, the perpendicular rod may pass through a suitably shaped elongate passage in the screen which fulfils the function of a guiding means. The movement imparted to the lunar image means will therefore follow the shape of the elongate passage. For example, for a wave-like aperture the elongate passage may be complementarily, substantially wave-like in shape.

[0025] Where the masking means has an axis of symmetry, the clock may be rotated by 180° to restart the lunar cycle. Alternatively, the drive means may be arranged so as to return the lunar image means to its starting position or to drive the lunar image means in the reverse direction.

[0026] The present invention will now be described in a non-limitative sense with reference to the accompanying Figure in which:

Figure 1 illustrates a front elevation view of a preferred embodiment of the lunar clock of the invention;

Figure 2 illustrates a front perspective view of a preferred embodiment of the lunar clock of the invention;

Figure 3 illustrates a rear perspective view of a preferred embodiment of the lunar clock of the invention.

[0027] With reference to Figure 1, a preferred embodiment of the lunar clock of the invention is designated generally by reference numeral 1 in which the masking means takes the form of a screen 2 having an elongate, wavelike aperture 3. The lunar image means in the form of a transparent disc shaped member 4 is driven by driving means (not shown) along the wavelike path 5 in front of the flat screen 2.

[0028] With reference to Figure 2, it will be seen that flat screen 2 is dark in colour to simulate the night sky. It is provided with an elongate passage 6 which serves to guide the movement of the lunar image means 4 complementarily to the wavelike, S-shaped aperture 3.

[0029] Figure 3 illustrates in perspective view the rear of the screen and the mode of attachment of lunar image means 4 (shown in dotted lines). The rear of the flat screen 2 is fitted with two substantially parallel and substantially vertically mounted guide rods 7a and 7b. A substantially horizontal bar 8 is coupled to the guide rods 7a, 7b by coupling means 9a, 9b in a loose manner. Appropriate driving means (not shown) may be used to permit vertical movement of the coupling means 9a, 9b along guide rods 7a, 7b so as to permit vertical movement of the horizontal bar 8 across the rear of the face of the screen 2. The horizontal bar 8 is provided with a free sliding sleeve 10 which takes the form of a T-shaped arrangement which is attached to the rear of the lunar image means 4 through the elongate passage 6. It will be apparent that the vertical movement of the horizontal bar 8 across the rear of the screen permits the free sliding sleeve 10 to follow the path of the elongate passage 6 which thereby causes the lunar image means 4 to follow the wavelike S-shaped path of aperture 3.

Claims

1. A lunar clock capable of mimicking the phases of the moon in at least a part of the lunar cycle, said clock comprising:

a lunar image means capable of exhibiting in an unmasked portion an image of the illuminated part of the moon in a phase of the lunar cycle and in a masked portion an image of the non-illuminated part of the moon in that phase of the lunar cycle;

masking means for partially and variably masking the lunar image means to define the masked and unmasked portions thereof; and

drive means for imparting relative cyclical movement tc the lunar image means and masking means through positions which mimic each phase in the lunar cycle or a part thereof.

2. A lunar clock as claimed in claim 1 capable of mimicking the phases of the moon in the whole of the lunar cycle.

3. A lunar clock as claimed in claim 1 or 2 wherein the lunar image means comprises a substantially flat, disc-shaped member.

4. A lunar clock as claimed in claim 3 wherein the disc-shaped member is substantially circular.

5. A lunar clock as claimed in any preceding claim wherein the masking means is a substantially flat screen with an elongate aperture.

6. A lunar clock as claimed in claim 5 wherein the lunar image means is mounted to the rear or front of the flat screen.

7. A lunar clock as claimed in claim 5 or 6 wherein the lunar image means is mounted to the rear of the screen, the unmasked portion of the lunar image means being visible through the aperture and the masked portion of the lunar image means being hidden behind the surface of the screen in order to simulate a phase in the lunar cycle.

8. A lunar clock as claimed in claim 5 or 6 wherein a transparent lunar image means is mounted to the front of the screen such that light passing through the aperture in the screen and through the lunar image means defines the unmasked portion thereof and light prevented from passing through the lunar image means by the screen defines the masked portion thereof in order to simulate a phase in the lunar cycle.

9. A lunar clock as claimed in any of claims 5 to 8 wherein the elongate aperture is a wave-like aperture.

10. A lunar clock as claimed in claim 9 wherein the wave-like aperture is a substantially S-shaped aperture.

11. A lunar clock as claimed in claim 10 wherein the substantially S-shaped aperture has rotational symmetry.

12. A lunar clock as claimed in either of claims 10 or 11 wherein the tips of the S lies in a common, substantially vertical plane with the middle of the S having a lateral width which is the maximum lateral width of the aperture and which is approximately equivalent to the diameter of the lunar image means.

13. A lunar clock as claimed in claim 9 wherein the elongate aperture of the flat screen is approximately half of a substantially S-shaped aperture in a horn-like configuration.

14. A lunar clock as claimed in either of claims 5 or 6 wherein the lunar image means is movably attached to the front or rear of the screen whereby the drive means causes the lunar image means to cyclically traverse the path of the elongate aperture.

15. A lunar clock as claimed in any preceding claim wherein the lunar image means is driven by the drive means so that its movement complements the shape of the aperture.

16. A lunar clock as claimed in claim 15 wherein the lunar clock further comprises a guiding means so as to ensure that the lunar image means is driven by the drive means such that its movement complements the shape of the aperture.

17. A lunar clock as claimed in claim 16 wherein the guiding means is an elongate passage or an upstanding flange to the rear of the masking means.

18. A lunar clock as claimed in claim 17 wherein the elongate passage or the upstanding flange is a wave-like shape.

19. A lunar clock as claimed in of claims 5 to 18 wherein the rear of the flat screen is fitted with a pair of substantially parallel and substantially vertically mounted guide rods located outside the maximum lateral extent of the aperture and wherein a substantially horizontal bar is loosely coupled to the pair of guide rods at each end by coupling means so as to move vertically thereon and permit vertical movement of the horizontal bar across the rear of the face of the screen, said lunar image means being attached to the substantially horizontal bar.

20. A lunar clock as claimed in claim 19 wherein the guide rods are located at the outer edges of the rear of the screen.

21. A lunar clock as claimed in either of claims 19 or 20 wherein the horizontal bar is provided with a free sliding sleeve, wherein the free sliding sleeve is attached to the rear of the lunar image means.

22. A lunar clock as claimed in claim 21 wherein the free sliding sleeve comprises an integral perpendicular rod attached to the rear of the lunar image means, the integral perpendicular rod being dependent from about the central point of the sleeve so as to form a substantially T-shaped arrangement.

23. A lunar clock as claimed in claim 22 wherein where the lunar image means is located at the front of the screen, the perpendicular rod passes through a suitably shaped elongate passage in the screen so that the movement imparted to the lunar image means follows the shape of the elongate passage.

Drawing