Many examples of timepieces are provided with means of illumination, generally in order that a user can read the time in the dark. For example, a clock or watch may be provided with a light that comes on when a button is pressed. Often the light remains on for just a short duration, sufficient for the time to be read.

Other functions for lighting on a timepiece have also been developed. For example, JP 2001-183480 discloses an alarm clock having a plurality of light sources that are able to emit different colour combinations. These are arranged around the periphery of a time display panel and flash when the alarm causes a melody to be generated.

Different lighting arrangements have even been used as a way of displaying the time. For example, GB 2 202 972 discloses a timepiece having a variable colour display for providing an analogue indication of the time. The timepiece includes a display having 12 regularly spaced colour display elements (representing each five minute period of an hour). The display elements can be illuminated in different colours to indicate various time limits and a measured value of time.

GB 2 281 420 discloses a timepiece in which different portions of the timepiece are illuminated independently with different colours at set time intervals. From this, according to the particular combination of colours displayed, a user can determine the time of day.

GB 2 367 385 discloses a clock having at least two regions the visual characteristics of which can be changed over time. The visual characteristics of each region can be compared in order to determine a particular time.

The present applicant has developed a timepiece which itself appears to change colour in response to a timing event.

According to a first aspect of the present invention there is provided a timepiece including a housing incorporating a time display panel, at least part of the housing being able to transmit light, and light source means capable of emitting a plurality of colours located within the housing, and means for causing the light source means to change colour in response to a timing event, such that substantially the whole of the interior of the housing is illuminated with a respective different colour by the light source means, said illumination being visible through the light-transmissive housing.

This arrangement allows different colours to be produced within the timepiece, in response to a particular timing event. The light source means being located within a light- transmissive housing allows the different colours emitted to be viewed through the housing.

This gives an impression that the timepiece itself is changing colour thereby providing a significant visual effect for the user.

In the preferred embodiment the light-transmissive housing is of a semi-opaque material and has a substantially constant thickness. A semi-opaque material provides a diffusing effect on the light and prevents the illumination being brighter than desirable. The constant thickness of the housing allows a uniform luminosity to be achieved.

Preferably the light source means has a wide angle. This facilitates uniform luminosity, since the different parts of the housing of the timepiece can be illuminated to substantially the same extent.

The timepiece preferably further includes a transparent inner housing within which is situated the light source means. This allows mixing of light emitted by the light source means prior to it reaching the light-transmissive housing.

Preferably, a circuit board is provided within the housing of the timepiece; the light source means, at least on integrated circuit chip and an LCD interface for the time display panel are mounted on the circuit board and the circuit board is positioned within the housing of the timepiece such that the interior of the housing is substantially empty. This reduces obstruction of light from the light source means so that the illumination of the housing is substantially uniform.

In the preferred embodiment the timepiece is a clock having a plurality of feet, at least one of which operates as a switch. Preferably, operation of the switch serves to terminate the indication of an alarm function. This enables a particular function of the clock to be actuated by striking the top of the clock. Preferably, operation of the switch serves to cause the light source means to switch on or off or to change colour.

Preferably the timepiece includes a multi-position switch, the position of which controls the particular response for the light source means to the timing event. This allows the user to select the visual effects required.

Preferably the timing event is the change of hour and/or an alarm indication. This enables the user to enjoy different visual effects throughout the day. The light source means are also able to enhance the alarm function of the timepiece.

The light source means preferably comprises a plurality of LEDs. LEDs are small, and come in many different colours. LEDs give a high brightness, but have low power requirements. This makes them particularly suitable for this function.

Preferably a given number of individual light source means are configured to emit a greater number of different colours. For example, four individual light source means can be configured to emit twelve different colours. This enables a simple structure to provide a greater visual effect.

In the preferred embodiment, the timepiece includes an LCD time display wherein one or more batteries of a first type are used to supply the light source means and one or more batteries of a second type are used to supply the LCD time display. Separation of the power requirements means that if the batteries powering the light source means run down, the user is still able to use the timepiece to keep track of the time.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Fig. 1 is a front view of a clock in accordance with the present invention; Fig. 2 is a view, similar to Fig. 1, showing the assembly of the clock; Fig. 3 is a perspective view of the housing of the clock of Fig. 1; Fig. 4 is an enlarged view of the bottom of the clock of Fig. 1; Fig. 5 is a perspective view of the bottom of the clock; Fig. 6 is a side plan view of the interior of the clock; and Fig. 7 is a top plan view of the interior of the clock.

Referring now to the drawings, Fig. 1 shows a clock 10 comprising a housing 11 of injection moulded plastic material. The housing is generally cubic and is of semi-opaque material. It has a soft, rubbery coating. A preferred material is ABS of a constant thickness of between lmm and 3mm. Such a material has good heat resistance without being prone to deformation.

A separate base 12 is provided for the housing and this is preferably of the same material as the housing and is also injection moulded. The housing 11 and base 12 are connected

together using ultrasound sealing as shown in Fig. 2. The front of the housing has an aperture 15 (Fig. 3) having clips 16 located at one edge thereof. Fitted into this aperture with the assistance of the clips 16 is a transparent polarised LCD panel 20. The indicia of the display panel 20 are arranged to be backlit.

Within the housing 11, located behind display panel 20, is a circuit board 71 upon which is mounted one or more integrated circuit chips, an LCD interface for panel 20, and a plurality of light sources. The light sources are preferably superflux LEDs which give a high brightness with a wide angle while being capable of running off low voltage power sources.

Referring now to Figs 4 and 5, the base 12 incorporates a recess 30. The recess incorporates a compartment 31 for receiving four AAA batteries. A separate compartment 32 is provided for two AG13 button cells. The batteries are covered by a battery cover (not shown) which is attached by means of a clip 33.

Various switches are provided within recess 30 for operation by a user. Four push buttons 41,42, 43 and 44 are respectively marked"UP","DOWN","SET", and"ALARM".

These buttons are used to alter the digital display on panel 20 as is conventional. A three position slider switch 50 is also provided. The left hand position is marked"DEMO", the middle position is marked"OFF"and the right hand position is marked"ON".

Two further push switches 53 and 54 are provided in the form of spring-biased plungers, the tips of which constitute two of the four feet of the clock. The front feet 51,52 are conventional fixed feet. The spring force with which plungers 53,54 are biased, is sufficiently strong that they are not actuated by placing the clock normally on a surface.

However, if the clock is struck relatively sharply, or tapped, from above, both switches 53 and 54 are actuated.

A circuit board 72 is provided for connection to buttons 41 to 44 and switches 50,53 and 54.

Figs 6 and 7 show the arrangement of the LEDs 63,64, 65,66 within the housing 11 of the clock. The LEDs 63,64, 65,66 are arranged within a transparent inner housing 67.

A-rear wall 61 of the housing 11 incorporates an electrical connection 62 for an a. c adapter if required.

The clock 10 is also provided with an audible alarm in the form of a buzzer. The arrangement is such that the LEDs 63,64, 65,66 and the alarm are powered by the four AAA batteries housed in compartment 31, while the display panel 20 and clock are run off the two button cells in compartment 32. The electronics are powered through a voltage regulator using a TTL 5v based system. An IC chip operates the LCD display 20 and also the light control feature of the LEDs 63,64, 65,66. Dependent on the particular light source used, a Darlington driver chip is used to isolate the integrated circuit from the high voltage, high current load.

The clock is configured so that operation of a single one of, or a combination of, the LEDs illuminates the whole of the interior of the housing 11 with a respective different colour.

The basic operation of the clock will now be described. With the slider switch 50 in its "ON"position, there is a predetermined colour for each hour of the day, i. e. twelve different colours. The colour changes on the hour, every hour. As the hour changes, the clock scrolls relatively-quickly through all twelve colours before settling on the predetermined colour for that hour. The colour then remains the same until the next hour arrives.

With the switch 50 in its"OFF"position none of the LEDs is normally illuminated.

However, upon change of the hour, the clock scrolls through all twelve colours, settles on the predetermined colour for that hour for a limited period of 30 seconds and then is extinguished until the next hour arrives.

When the alarm goes off, the colour of the light scrolls through each of the twelve colours five times before stopping. Each colour change lasts 0.5 seconds and thus the whole process lasts a maximum of 30 seconds.

When the function switch 50 is in its"DEMO"position, the clock simply scrolls through all twelve colours in turn, to give an attractive display, and also to enable a check to be made that all the LEDs are operating satisfactorily.

In the preferred embodiment, the twelve different colours are achieved by various combinations of four coloured LEDs, red (R), green (G), blue (B) and amber (A), as follows: R; R+G; R+G+B; R+G+B+A; G; G+B ; G+B+A; B; B+A; A; A+R and A+G.

Switches 53,54 are used in combination to switch off the alarm buzzer when it is sounding.

When this occurs, and switch 50 is in the"OFF"position, one of the LEDs switches on for 30 seconds before being extinguished. If, however, switch 50 is in the"ON"position, the LEDs cycle quickly through the various colours back to the original light colour which was showing immediately before the alarm sounded.

An advantage of the above-described clock is that it provides numerous attractive display features, which can be selected by a user. Since the housing is of semi-opaque material, and has a constant thickness, this permits a uniform luminosity to be achieved. The dual use of some of the feet to switch off the alarm is also advantageous.

Various modifications may be made to the above-described clock. In particular, a fading circuit may be provided to enable gradual colour changes to be produced. This feature may be set in the factory, or may be selectable by a user.

The clock may be of any suitable shape. For example, it could be generally spherical instead of generally cubic.

The alarm may be switched off by operation of only one of switches 53,54. Indeed, only a single foot switch 53 may be provided. Alternatively, three or all four of the clock's feet may have the function of a switch. In a further modification, all four feet are conventional, and a separate control button, e. g. at the top of the clock, is provided to switch off the alarm.

The audible alarm feature may be omitted. Alternatively, the audible alarm feature may be incorporated, but may be selectively deactivated by a user.

Instead of substantially the whole of the clock changing colour, only a part thereof may do so.

Different coloured LEDs may be provided, and different combinations of LEDs may be employed to produce a different range of colours. The inner housing within which the LEDs are arranged may be clear or coloured to provide different effects. Up to twelve light sources may be provided. In addition to red, green and blue LEDs, the incorporation of cyan and/or amber units produces a better range of output colours. For other colours a diffusing element of the appropriate further colour is positioned over selected LEDs within the housing 11. In an alternative embodiment, 24 different colours may be produced by up to 24 light sources.

Neon tubes or other light sources may be used instead of LEDs.

The timepiece may incorporate a radio, which may be a radio alarm.

The timepiece may be in the form of a watch, with the various control buttons arranged around the edge thereof.