GB2262988A - Manually operated device for illuminating wrist-watch or instrument displays. - Google Patents

Abstract

A wrist-watch - body 3 - or other instrument having a display has a manually operated device for occasional or repeated illumination of the instrument's display comprising a piezoelectric generator 5, 6 and 10 and a slot fluorescent lamp 1s illuminating the dial 4. The lamp can be designed as a low-pressure fluorescent lamp with an argon-neon mixture with mercury vapour, in a reflector arrangement. The inner surface of the discharge lamp can be coated with either a luminescent material with an afterglow or without an afterglow. The piezoelectric generator is operated by a lever 10 having a push-button 12 thereon. <IMAGE>

Description

Manually Operated Device for Occasional or Repeated Illumination of Watch and Instrument Dials/Displays This invention relates to improvements in the illumination of instrument dials/displays and, more particularly, to manually operated devices for the occasional or repeated illumination of wrist and other watches, alarm clocks, instrument displays, faces and indicating places including alpha-numeric and symbolic indicators thereon, pointers and the like, the said illuminating devices working independently from the energy sources and mechanisms of the said instruments.

There is a wide range of instruments having displays, faces, dials, and indicating places; for personal use, such as wrist-watches, compasses, instruments for diving such as depth-meters; and heavy and bulky instruments on stationary devices or machines for other uses such as gas-meters, barometers, thermometers, manometers and revolution counters, which require occasional or periodically repeated reading and checking.

These may be in dark or poorly lit places, or need reading at night or when other illumination is not available, or is not desirable for some other reason. All of these instruments, as well as many not specifically mentioned, have either their own illumination or are illuminated from the outside. One solution to this problem is the ''luminous dial", in which the hands or pointers and the indicating marks are coated with a phosphorescent substance which will emit some light in darkened surroundings. However, to be effective such dials need to be larger than is often desirable, and their use is being discouraged on health grounds (bearing in mind emitted radiation).

Some instruments have their own illuminating device, with a wrist-watch with a digital display typifying the class. As it is knon. formillg figures on the digital display of the wrist-watch is done by using a dynamic scattering of light beams in nematic liquid crystals when an electric field is applied.

In twilight dusk or darkness illumination for the display is usually provided by a miniature light bulb (an incandescent lamp) energised by a dry throw-away battery or an accumulator/ rechargeable battery energising the time-metering device as well.

The bulb illuminates the display of the watch by direct incident light, usually from the side at a very acute angle. This arrangement has many drawbacks. Firstly, a large amount of light is uselessly absorbed in the space of the wrist-watch casing.

Secondly, another substantial amount of light is lost by interference with the partial or total reflection of ambient light on glossy surfaces of the display towards the eyes of the user, often hindering rather than helping the user to distinguish the indication. The resulting light is bad, blinking and insufficient, and, due to its poor quality making the reading slower, thus shortening the life of the battery and discouraging the user from frequent usage.

In the special (but frequently met with) borderline case of twilight it is impossible to react the indication at all. Moreover, at direct incident and reflected light of given intensity, even at high colour saturation, the differentiating sensitivity of the human eye is low and the indications tend to merge into their background.

Existing systems and arrangements can hardly satisfy users' requirements, except perhaps in absolute darkness, and even then not satisfactorilv.

Essential Technical Features of the Invention In view of the foregoing limitations and shortcomings of prior art illuminations for instruments, as well as other disadvantages not specifically mentioned above, it should be apparent that there exists a need in the art for an illuminating device for the above instruments which provides effective illumination of the instrument dial/display. Additional benefits would be simplicity, reliability, handiness and readiness for use, inexpensiveness in mass production, the ability to be built in without significant changes in present design of the wrist-watch (or other instrument), provision of lighting strong and steady enough for reliable readings to be taken, and independence from the energy source of the instrument.

It is, therefore, a primary objective of this invention to fulfil this need by providing a novel illuminating device for instruments comprising a manually operated electric energy generator with an electric feeder line and a light source mounted in the instrument independently of other working parts and sources.

More particularly, it is an object of this invention to provide a device designed as an illumination unit, wherein the electric energy generator is a piezoelectric generator comprising a piezoelectric crystal with output electrodes on its ends, said crystal being pressed down and released again by an operating lever through a transmission mechanism generating high voltage impulses energising, through a feeding line, a fluorescent lamp or radiating source for illuminating such displays.

Brief desctptio'i of tli e dry wings Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a structural and partly schematized view of the example, an analogue wrist-watch, provided with the illuminating device.This comprises a piezoelectric generator and a slot fluorescent lamp provided with a lens for illuminating the dial Figure 2 shows a top cross-sectional view of the slot fluorescent lamp provided with the lens Figure 3 shows a side cross-sectional view of the slot fluorescent lamp provided with the lens (illuminating the dial) Figure 4 shows a structural and partially schematized view of another embodiment of the illuminating device in the analogue wrist-watch comprising the piezoelectric generator and a circular circumferential slot fluorescent lamp provided with the lens and illuminating the dial Figure 5 shows a structural and partially schematic view of another embodiment of the illuminating device in the analogue wrist-watch comprising the piezoelectric generator and an ultraviolet source illuminating the dial by ultraviolet radiation, this dial comprising figures and hands coated with luminescent material Figure 6 shows a structural and partially schematized view of the illuminating device embodied in (as a different example) an electronic digital wrist-watch comprising the piezoelectric generator and a straight (cylindrical) slot fluorescent lamp provided with the lens and illuminating a liquid crystal display Figure 7 shows a top cross-sectional view of the straight slot fluorescent lamp provided with lens Figure 8 shows a side cross-sectional view of the straight slot fluorescent lamp provided with lens, illuminating the liquid crystal display Figure 9 shows a structural and partly schematized view of another embodiment of the illuminating device in an electronic digital wrist-watch, comprising the piezoelectric generator and a flat fluorescent lamp positioned under the liquid crystal display, and illuminating the display by indirect light passing through from the background. This figure also illustrates another embodiment of the lever transmissions system driving the piezoelectric generator Figure 10 shows a top view of the flat fluorescent lamp used in this device Figure 11 shows a side crcss-sectional view of the liquid crystal display above the flat fluorescent lamp along the longitudinal plane C)f summetry Figure 12 shows a side crss-sectional view of the liquid crystal display above the flat fiuorescent lamp along the transverse plane of symmetry Figure 13 shows an outward appearance of the wrist-watch casing shown in Figure 9, with movable side wall used for driving the piezoelectric generator Figure 14 shows another embodiment of the lever transmission system tor driving the piezoelectric generator Figure 15 illustrates how the illuminating device might be operated to illuminate the dial of an analogue wrist-watch Figure 16 illustrates how the illuminating device might be operated to illuminate the dial of a digital wrist-watch Detailed description ofthe preferresl e' ;lbodil? z en ts Referring now in detail to the drawings there is illustrated in Figure 1 a structural and partly schematized picture of the example (an analogue wrist-watch) provided with the manually driven illuminating device.The movement (which works the watch) is omitted for clarity: this is also done in the other drawings, and emphasises the fact that the workings of the illuminating device are completely independent of the workings and energy sources of the watch (or other device).

The illuminating device in this figure consists of a modification of the slot (reflector) fluorescent lamp ls with a light concentrating (focusing) lens 2 accommodated together in a watch casing 3 at the edge of the dial 4. A piezoelectric generator comprises a piezoelectric crystal 5 with its output end (film or metal foil) electrodes 6 bedded or cast in an insulating (plastic) sleeve 7.

The piezoelectric crystal 5 may be made and cut from Seignette (Rochelle) salt, piezoelectric ceramic, or any other suitable piezoelectric material. A front end press face Sf and a rear end press face 8r are put to the cut ends of the piezoelectric crystal 5.

The output electrodes 6 are connected with the slot fluorescent lamp is by means of a feeder line 9. A driving (operating) lever 10 is carried in the case 3 by the pin 11. A cam curvature 10.1 is in touch with the front end press face 8f. A press button 12f is freely laid on the surface of the driving lever 10.

In operation, the press button 12f is alternately pressed and released by the thumb, displacing the lever 10 into the position lOph (shown in dotted lines), whence it returns. The cam curvature 10.1 presses the piezoelectric crystal 5 down between the faces Sf and Sr (which is supported against the retaining rest 13). This action generates electric current which lights up the slot fluorescent lamp Is in order to illuminate the watch figures 14 and the watch hands 15, both by direct incident and diffused reflected light.

The press button 12f slips slightly on the surface of the operating lever 10 being, as stated above, laid freely on the surface, and neither linked nor coupled.

Figure 2 shows in detail a top cross-sectional view of the modified tubular slot fluorescent lamp is (curved slightly in a convex direction). It also shows the lens 2 (both diagrammatically shortened as indicated by the broken lines), enlarged approximately three times from their representation in Figure 1. The lamp in the present invention is extremely simple and may easily be modified from a slot fluorescent lamp, which are currently manufactured in large numbers by well established techniques.

This is a variety of the so-called reflector fluorescent lamp having a modified curve of luminous intensity. It is usually designed with heated electrodes covered by emitting material and with a starter, an induction coil or similar. The luminance of the slot fluorescent lamp is increased by approximately four times in one direction compared to the standard fluorescent lamp. Its luminous flux may be optically focused.

The type P'c'l"'sed for the present invention has cold electrodes, is similar to the type called Slliizhjie, has no emitting material on the electrodes, no starter, no coil, nor any additional devices. It comprises a glass tube 1.I. with sealing caps 1.2 (alternatively the glass may be sealed itself). The cold electrodes 1.3 are sealed into the caps 1.2; they may be of nickel or iron wire, and shaped as single sticks.

A coat of of luminescent material 1.4 (indicated by a strip with dense dotting) covers the inner surface of the glass tube 1.1. The luminescent material may be any common fluorescent material such as (Ca,Zn)3(P04)2 or (CaSr)3(P04)2 with Sn activators.

The outer surface of the glass tube 1.1 is coated by a reflexive coat or layer 1.5 (indicated by a strip with a dashed line) and made of TiO) covering the whole of the outer surface except for the area facing the lens 2 (a gap of about 300, as shown in Figure 3). The inner filling of the lamp referred to in 1.6 may consist of an argon-neon mixture with mercury vapour, as is common in such lamps, with a normal low pressure of 400 Pa.

Figure 3 shows a side cross-sectional view of this lamp and lens arrangein ent slightly enlarged from Figure 9* with components labelled as before. The "window" is angled to the surface of the dial 4 (3 below the horizontal), as shown. for m.lxinlllm lighting effect. The lens 2 may be made of glass or plastic. or optionally omitted if the illuminaticn without it is feist to he adequate.

Driving the lever 10 down and up transforms mechanical energy into high voltages on the poles of the piezoelectric crystal 5.

This gives rise to a small electric current carried from the output end electrodes 6 through the feeder line 9 to the lamp electrodes 1.3. Since the discharge voltuge of the lamp is relatively low (at maximum hundreds of volts, compared to thousands at the poles of the piezoelectric crystal) the voltage is discharged in a series of discrete discharges dense enough to light up the fluorescent lamp Is, transforming all the ultraviolet radiation of the discharges into visible light in the luminescent material.

The high voltage (difference in electrostatic potential) arises both when the button 12f is pressed, and also when it is released. A few presses and releases should be sufficient to read the watch (or other instrument). The density of the discharges is sufficient to light the lamp continuously, with only slight fluttering. If this is objected to, the coating can include a phosphorescent material such as ZnS or CdS, or ZnO, in the form of a twinlayer arrangement. There is a broad spectrum of materials currently available which are suitable for this purpose.

As can be seen, the illuminating device can easily be built into any analogue wrist-watch, taking Up a minimum of space in the marginal parts of the watch case. There is no danger of the illuminating device affecting the workings of the watch nor, provided that it is properly insulated, will the high voltages generated by the piezoelectric crystal effect other electric parts of the watch or instrument (if there are any).

The length and diameter of the piezoelectric crystal determine its working voltage and the current generated. The longer the crystal, the higher the voltage, and the higher the frequency of discharges which will be generated in the lamp. The larger the cross section of the crystal in relation to its axis, the larger the electric current generated. A higher current will lead to fewer discharges, but more energetic ones. The choice of voltage and current must be made to suit the luminescent material used to coat the lamp. Generally, a longer and thinner crystal is more suitable for fluorescent coats, and shorter thicker crystals for phosphorescent coats.

An alternative method of determining the current/voltage delivery is by altering the pressure of the gas in the lamp.

Generally to increase the pressure decreases the frequency of the discharges, making them more intensive and therefore suitable for phosphorescent coatings. Decreasing the pressure increases the frequency of less intensive discharges, which is more suitable for fluorescent coatings.

Figure 4 shows another structural and partially schematized embodiment of the invention. A circular modification of the slot fluorescent lamp lsc with lens 2 is shaped round the dial circumferentially. It is connected to the piezoelectric generator through the line 9, as in the previous illustration. The light emitted by the circular slot lamp lsc in this Figure is radiated concentrically towards the middle of the dial 4, illuminating the whole dial by both direct incident and reflected diffused light.

The shape and disposition of the lamp is almost infinitely variable to suit a multitude of requirements.

Figure 5 shows a variant of the principle. In this, an ultraviolet source luv, energised by the piezoelectric generator as in the previous examples, has a clear glass tube, and it is the hands 15 1 and the figures 14 1 which are coated with the luminescent material (but much less than would be necessary for a luminous watch). The ultraviolet source luv may have a reflexive coat (or a reflexive plate) in order to increase the amount of ultra violet radiation going in the direction of the dial.

Figure 6 shows an emhodimellt preferable for electronic digital devices using liquid crystal displays with nematic liquid crystals.

A display 16 is accommodated in a watch casing 3. A straight cylindrical version of the slot fluorescent lamp is with the lens 2 is placed at the edge of the display to illuminate it. the workings of the various parts are as referred to in Figure 1, except that the button 12a is affixed to the lever 1() in this embodiment. The illumination produced as it comes from a linear lamp, is far superior to that produced in a conventiollal way, through a pinpoint source.

Figure 7 shows an enlarged top cross-sectional view of the lamp is, similar to that in Figure 2.

Figure 8 shows an enlarged side cross-sectional view of the lamp, similar to that in Figure 3. However, for optimum illumination the angle between the line FL and the horizontal should be somewhat greater: 90 is shown.

Figure 9 shows another embodiment suitable for electronic digital watches with liquid crystal displays. In this embodiment the illumination is not achieved by incident lighting (as in the previous embodiments) but by indirect light coming through the display from the background. The display 16, cut away to show the (in this case flat) modification of the fluorescent lamp if underneath, which sits in the case 3. The other parts have the same functions as in Figure 6, except that in this case the lever 10 is pressed down by the segment side wall 17 mounted on the pin 18, the segment side wall having additionally a tooth 19.

These move into the positions 17ph and 19ph when the side wall 17 is pressed.

The methods of illumination and of generating the power are totally independent.

Figure 10A shows a top view of the left hand portion of the modified flat fluorescent lamp if, showing the luminescent material 1.4 positioned immediately under the display 16 (not shown).

Figure 10B shows a top cross-sectional view of the right hand side of the same lamp, this time showing the gaseous filling 1.6.

Figure 11 shows a side cross-sectional view of the display 16 and the flat fluorescent tube along the longitudinal plane of symmetry. The display 16 consists of an upper plate of glass with an upper transparent electrically conductive electrode (made of tin dioxide, for example) in the form of a stylised figure of seven segments, in fact single electrodes; and of a lower glass plate with a lower transparent electrode, covering the whole of the glass plate in this case.

The distance between the two plates would be approximately 10-20 microns. Nematic liquid crystals are enclosed between the plates and sealed by rubber sealing strips. Black strips in this figure demarcate opaque areas in the liquid crystals when an electric field is applied to the figure electrodes. The arrows passing through the display element 16 from the discharge lamp illustrate places always transparent to light beams. The opacity has its origin in nematic liquid crystals owing to diffused reflections of light from the bunching of ions in the direction of the applied outer electric field.

The flat fluorescent lamp is placed immediately beneath the described display element 16 and consists of the parts described above, i.e. of the flat glass tube 1.1, sealing lamp caps 1.2 and electrodes 1.3.

The inner surface of the glass tube is coated with a luminescent layer 1.4 indicated by dense dots and filled with the gaseous filling 1.6. The outer surface of the glass tube is partially coated by the reflective coat 1.5.

Figure 12 shows the elements of Figure 11 in a cross-sectional view. The flattened transversal shape of the flat glass tube 1.1 can be clearly seen. The reflective layer 1 is seen covering the outer surface of the glass tube except the area facing the display 16. This area is only covered (on the inner surface) with the luminescent material 1.4.

For this embodiment the llua lescenì material should be of the phosphorescent type only. Agalill. tny of the binary inorganic compounds such as ZnS CdS 01 ZnO. with suitable activators, will suffice.

This form of illumination only be more satisfactory where there is no ambient light at all.

Figure 13 shows the outward appearance of the instrument shown in Figure 9. The (movable) segment side wall 17 is protruding from the sealing rim 20. The direction signs show the extent and direction of the movement of the wall in activating the generator.

Figure 14 shows still another arrangement of the power transmission system. In this case a free (i.e. not linked) press button 12f is provided with a recess 21 in its body, and with an extension 22 sliding in a guiding aperture 23. When depressed, these elements move into the positions shown at 12fph, 21ph and 22ph. The driving lever 10 is therefore depressed into position ooph.

Figure 15 shows the obvious wav of activating the device in an analogue wrist-watch, by pressing the button with the opposite thumb whilst using a finger to resist the pressure.

Figure 16 shows a similar situatioll with respect to one of the variants of the design.

Furtller notes 1) A piezoelectric generator can be of a conventional type, able to be easily miniaturised and to generate the discharge voltage high enough to produce the mentioned series of discharges lighting up a small size discharge lamp. The generator can easily be made waterproof and dustproof by an elastic cuff or cup packing on the operating lever, or by a separating membrane between the the transmission mechanism and the crystal, so separating and sealing the piezoelectric generator space completely.

The generator, as the most voluminous part of the illuminating device, will preferably be positioned in the marginal casing spaces of the body with the advantageous arrangement of the operating lever already described. Manufacturing of such a generator is well established for other applications, e.g. for lighters. Reliably connected to the discharge lamp it cannot unfavourably affect the other parts of the watch.

2) A discharge lamp can also be manufactured by well established techniques. With respect to the relatively high voltages generated by the piezoelectric generator its discharges can be struck cold, striking without any starter and having its cold (unheated) electrodes shaped as hollow cylinders or as flattened hollow cylinders made of iron or nickel without any emitting material added.

All this makes such a discharge lamp extremely simple. Owing to the mentioned discharging high voltage there are many possible variants of the gaseous filling at various pressures.

One of the most advantageous is an argon-neon mixture with mercury vapour at a pressure of about 400 Pa, where of necessity miniature sizes of such discharge lamp favourably add to lowering the discharge voltage. The lamp should preferably be manufactured without lamp caps, with tungsten wire electrodes being glass sealed in at its ends only. Furthermore, a reflecting layer can be coated on the glass tube from the outside, the luminescent material being coated from the inside.

3) A luminescent/phosphorescent material with sufficient afterglow or persistence to coat on the inner surface of the discharge lamp can be chosen of some binary organic crystalline compounds on the basis of ZnS (zinc sulphide) or CdS (cadmium sulphide) or some oxide luminescent materials of the ZnO (zinc oxide) type, with suitable activators being able to give out luminescence at practically all known ways of exciting.

For example a phosphorescent material MgF2 with Mn as activator in light yellow-orange colour or a twinlayer luminescent material with the first layer consisting of ZnS with Ag as activator is exciting luminescence without persistence or afterglow and it is used as a source for exciting a second layer consisting of ZnCdS with Cti as activator. Excited by the first layer the afterglo\v of the second layer lasts a few seconds with a light yellcw-green coloul-.

In an alternate embodiment a luminescent/fluorescent material without persistence can be used, as for example (Ca,Zn)3(PO4)2 with Sn activator for white colour light. This requires however. continuous operation of the piezoelectric generator lever ci tiring reading of the indications on the display. While the invention has been illustrated and described by way of example with reference to the accompanying drawings as embodied in one (wrist-watch) type of instrument, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing from the scope and spirit of the present invention.

Claims (6)

1. A wrist-watch with an analogue display and other instruments with said type of display as well as other instruments with other types of displays, faces or indicating places having a manually operated illuminating device for occasionally or repeatedly illuminating said displays, faces or indicating places, said illuminating device comprising a piezoelectric generator as an energy source combined with a discharge lamp as a light source.

2. A wrist-watch and other instruments having the manually operated illuminating device as claimed in Claim 1, wherein the illuminating device comprises a flat discharge lamp positioned beneath the transparent or translucent displays, faces and indicating places to illuminate indications thereon by passing light through from background from said discharge lamp.

3. A wrist-watch ancl other instruments having the manually operated illuminating device as claimed in Claim 1 or Claim 2, wherein the flat discharge lamp is a low-pressure fluorescent lamp filled with argon-neon mixture and mercury vapour and provided with a directionallv reflecting layer.

CLAIMS (cont'd)

4. A wrist-watch and other instruments having the manually operated illuminating device as claimed in Claim 1 or Claim 2, wherein the discharge lamp is provided with a fluorescent material without any afterglow or persistence on its inner surface, i.e. said fluorescent material gives out luminescence only when being immediately excited.

5. A wrist-watch and other instruments having the manually operated illuminating device as claimed in Claim 1 or Claim 2, wherein the discharge lamp is provided with a phosphorescent material with an afterglow or persistence on its inner surface, i.e. said fluorescent material still gives out luminescence after excitement has ceased (it gives out a phosphorescent glow).

6. A wrist-watch and other instruments having the manually operated illuminating device substantially as described herein with reference to Figures 1-16 of the accompanying drawings.