BACKGROUND OF INVENTION

The invention described herein relates to improvements made to a time keeping device that uses light emitting diode (LED) powered by a lithium cell through an electronic circuitry for illuminating the dial. The device also consists of a switch to activate the LED to illuminate secondary dial made from a transparent material like a special grade acrylic having very high light transmission ratio and on which a pattern is engraved. The LED positioned near the periphery of the transparent dial when energized accentuates the pattern etched on its face. This not only allows easy reading of time in the dark but also enhances aesthetics of the watch. The parts that together perform the illumination function are packaged in a kit and provided with a separate lithium battery capable of delivering a higher voltage required for lighting up the LED and for providing a longer life of the illumination function. This watch having a separate battery ensures normal functioning of time keeping portion device even if the illumination function does not work due to failure of lithium battery.

PRIOR ART

Several methods of illuminating the dial face have been used in electronic time keeping devices; one of the most common ones being coating of the dial surface with a luminous compound that glows when it is dark. Yet another method of dial illumination commonly employed is coating the dial surface of the device with an electro luminescent material that glows when an electric current is applied to it. The first method is cumbersome to manufacture and requires statutory regulations to be followed since most of the coating substances available are radio active. The second method places severe constraints on watch design due to the requirement of a transparent plastic layer on the back of which the electro luminescent coating is applied. This transparent layer gets illuminated at the press of a button making it possible to read time. Both methods of illumination explained above have severe restrictions in color and time readability that can be achieved on the dial face due to inherent deficiency in technology.

Using light emitting diodes in a device that is small has a significant advantage over the conventional methods explained above. The LED with low power consumption and high luminous intensity coupled with a smaller size has become ideal for use in time keeping devices like watches and clocks for illumination. The illumination of the device is carried out with the intention of either making it convenient to read time in the dark or for decorative purposes or both.

The light emitting watch in the invention JP 2002-022849 describes a method of illuminating the dial using protrusion parts on light guide plate facing the optical axes of LED bulbs placed at the 12* and 6 hour positions. The dial illumination system described in the invention CN1301360 also speaks about a light guide beneath a light transmitting dial. The bottom surface of the light guide consists of a pattern of white reflective dots that internally reflect light towards the dial. In both of the above cases, the light guide plate cannot be manufactured without the making of a tool for molding of light guide plate. This also places a constraint in terms of proliferation of patterns and
complicated profiles on the light guide plate since each pattern will call for a different set of tooling.

The patent ref JP 07-248385 describes the invention of lighting system for watch which leads the light from a light source to the circumference of a dial window via a light guide ring thus ensuring a uniform light intensity across the entire watch face. The apparatus for illuminating dial of watch described in the invention JP 50-024284 has a light emitting bulb placed nearer to the center. A reflective film and a reflective plate coupled with a gradation coating on the back side of the dial ensure uniform illumination of the dial. The above 2 patents describe a technical solution for uniform lighting of the dial face.

The invention of a luminous wrist watch described in CN 2634510 is fitted with an LED on a bus bar mounted on the bottom of MG such that when the LED is powered, light falls directly on the face of the dial. This type of a design has the disadvantage of poor aesthetics due to the bus bar placed below MG.

OBJECTIVES OF INVENTION
The main object of the invention is to provide a quartz analogue time keeping device with an improved method of displaying time in the dark using a light emitting diode instead of the conventional electroluminescence method. This method neither affects reading time in the dark nor affects aesthetics of dial face.

Another object of this invention is to provide a quartz analogue time keeping device with a display that is visually appealing when the light emitting diode is energized in the dark.

Yet another object of this invention is to provide a quartz analogue time keeping device with a separate power source for working of the light emitting diode such that it does not affect the normal function of time keeping.

STATEMENT OF THE INVENTION
According to this invention, the quartz analogue time keeping device is provided with a light emitting diode that not only helps to read time in the dark but also provides better aesthetics with the help of a secondary dial with etched pattems that get accentuated when the light emitting diode is energized.

BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows the exploded view of kit
FIG. 2 shows cross-section indicating concealed position of LED
FIG. 3 shows the plastic dial with patterns etched on it
FIG. 4 shows the metallic dial with dial feet on both sides
FIG. 5 shows the glowing of LED in the dark

DETAILED DESCRIPTION OF THE DRAWING
The exploded view of the glowing face kit is given in FIG.1 which shows an additional 3 volt lithium battery (4), the printed circuit board with LED (1) and metal components like metal mount (5) and negative contact (2) that can be assembled to form a sub assembly. The plastic housing (3) is the base on which all other parts are mounted to form the glowing face kit.

The LED (6) is soldered on the printed circuit board such that the sub assembly when placed into the case, the LED will be concealed below the case (FIG.2) at the periphery and the maximum amount of light is falling on the plastic secondary dial.

The plastic secondary dial with patterns (FIG.3) at the bottom is placed over the metallic dial. The metallic dial has dial feet on the top surface (FIG.4) to locate the plastic dial and is designed in such a manner that it does not hinder placing inside the case. Dial feet at the bottom of metallic dial will locate it on the time keeping portion of the circuitry.
When the button provided in the outer periphery of case is pressed, the LED glows (FIG.5) since the circuit is closed. The plastic dial has a high light transmission ratio and high refractive index and therefore light from the LED is uniformly spread over the face thus allowing the wearer to read time when it is dark.

WE CLAIM

1) A quartz analog time keeping device consists of 2 dials - one metal (primary) and one plastic (secondary) fitted with a surface mounting type light emitting diode (LED) at the periphery connected to a switch that gets energized when the switch is pressed. This in turn illuminates secondary dial and highlights patterns etched on it. The device can also be assembled with more than one LED to give brighter light and also enhance the look with different colors of LED. The other variation of the same being peripheral illumination using secondary dial with cutout in the center.

2) The quartz analog time keeping device as claimed in claim 1 illuminates the watch face brighter than in the case of electroluminescent sheet due to the use of LED.

3) The quartz analog time keeping device as claimed in claim 1 to 2 allows reading of time in dark when a switch placed on the outside of the case is pressed.

4) The quartz analog time keeping device as claimed in claim 1 to 3 is assembled with a secondary dial made from a transparent material like acrylic with very high light transmission ratio that acts as a media to ensure uniform dispersion of light when LED is energized.

5) The quartz analog time keeping device as claimed in claim 1 to 4 allows the option of designing the device with a shaped dial opening which is difficult in the case of an electroluminescent dial.

6) The quartz analog time keeping device as claimed in claim 1 to 5 can also be assembled with the secondary dial of different colors thus creating interplay between the color of LED and the color of secondary dial.

7) The quartz analog time keeping device as claimed in claim 1 to 6 can also be assembled with patterns created on the 1 metallic dial through printing or such means and thus create interplay between the patterns on the metallic dial and patterns on plastic dial.

8) The quartz analog time keeping device as claimed in claim 1 to 7 has the secondary dial etched with patterns (by using for example a laser beam) that get accentuated when the LED is energized.

9) The quartz analog time keeping device as claimed in claim 1 to 8 has the light emitting diode positioned into a concave groove on the periphery of the transparent dial such that light is reflected through it.

10) The quartz analog time keeping device as claimed in claim 1 to 7 has the light emitting diode concealed inside the case and is not visible to the wearer.

11) The quartz analog time keeping device as claimed in claim 1 to 8 is powered by a separate 3 volt lithium cell which ensures that the regular function of timekeeping in a watch is not affected by the constant use of LED.

12) The quartz analog time keeping device as claimed in claim 1 to 9 does not affect size due to the fitting of LED and transparent dial into it.

13) The quartz analog time keeping device as claimed in claim 1 to 10 where the position of LED can easily be adjusted by changing the position of the extension PCB to which the LED is soldered to suite various case opening sizes and shapes.

14) The quartz analog time keeping device as claimed in claim 1 to 11 where the position of LED is adjustable allows design of case opening size less than 20 mm or more than 28 mm which are rare in such watches with luminous dial.

15) The quartz analog time keeping device as claimed in claim 1 to 12 has all the parts like LED, a 3 volt lithium battery, a circuit board, etc mounted on a plastic housing and can be assembled into a sub assembled unit that can be easily assembled into the device.