GB1573408A - Electronic timepieces - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO ELECTRONIC TIMEPIECES (71) We, KABUSHIKI KAISHA SUWA SEIKOSHA, a Japanese company, of 3-4, 4-chome, Ginza, Chuo-ku, Tokyo, Japan, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to electronic timepieces and although not limited exlusively to electronic wrist watches is primarily intended for and is of greatest advantage when applied to, electronic wrist watches.

Electronic timepieces include function controlling manual input portions by which expression is meant manually operable control means operable to select among the different functions which the apparatus in the timepiece is capable of performing. To take the simplest and most common case, the apparatus in a timepiece is capable of performing the normal function of time-keeping. It must also, however, be capable of having the displayed time corrected when required (e.g. by comparison with a broadcast or other time signal) and accordingly the apparatus must be able to perform the additional function of changing its circuitry so that time correction can be effected - commonly by selecting the units of time (e.g. hours and minutes) to be separately corrected and then correcting the displayed values of those units.Selection among the different possible functions is performed by what is herein termed a manual input portion. The present invention is concerned with function selecting input portions provided in a timepiece or in a combined timepiece and calculator.

In a conventional balance wheel type of mechanical timepiece, the parts of the movement are all mechanical, comprising many small gear wheels, shafts, springs, screws and so on. In an electronic timepiece, on the other hand, e.g. in an electronic wrist watch, electrical parts - a quartz crystal oscillator, an integrated circuit, resistors, capacitors and so on, are used to perform the time-keeping function performed, in a mechanical watch, by the mechanical movement. In solid state electronic timepieces with non-mechanical displays, e.g. LED or LCD displays, - and such timepieces are becoming increasingly popular and in demand there are not even mechanically moving hands and gears for driving them.Nevertheless, mechanically moving parts are not entirely eliminated even in these timepieces, for there has to be provided what is herein termed a "manual input portion" i.e. manually operable controls. In a timepiece with an LED display a manual input portion is required for correction of the displayed time and for switching the timepiece on and off, while in a timepiece with an LCD display, in which, for reasons of economy in power consumption, the display is usually not left permanently operating, the manual input portion is also used for bringing the display temporarily into operation when the user wants to see the time. In electronic timepieces as at present in common use, the manual input portion is generally of the push button type.

The invention is illustrated in and explained in connection with the accompanying drawings, in which: Figure 1 is a face view of an electronic watch and may be regarded as showing equally a known watch and/or a watch in accordance with this invention if the strip shown dotted in Figure 1 is disregarded; Figure 2 shows a switch construction as used in a known watch as represented in Figure 1 if the dotted strip 6 is not ignored; Figure 3 shows a switch construction as used in carrying out this invention; Figures 4, 7 and 8 show touch detecting circuits for use in carrying out this invention; Figure 6 is a face view of a combined watch and calculator in accordance with this invention; and Figure 5 is an explanatory wave form figure.

Taking Figure 1 as showing a known watch, the manual input portion of this watch comprises three switches. 3 is a locking switch which is pressed when it is required to actuate the display and gives a click when pushed in. 4 and 5 are displayed time correction switches and are of push button construction. Switch 4 is a selecting switch which selects the time unit to be corrected (e.g. hours of minutes) and 5 is a switch which is used to perform the actual correction, i.e. it is a time setting switch. Figure 2 of the accompanying drawings is a sectional view showing a typical known construction for the switches 4 and 5.The selecting switch 4 comprises a push button, also referenced 4, biassed outwardly with respect to the watch case by a helical spring 7 and slidable longitudinally in a tube 8. 9 is a gasket. 10 is a member - it may be an E-ring - for guarding against the push button 4 being accidentally pushed in. 6 is a contact spring co-operating with a contact pin 11 mounted in an insulating base 18. The switch 5 is of similar construction with a button (also referenced 5), a spring 12, a tube 13, a gasket 14, and an E-ring 15. When the button 5 is pressed, the contact spring 6 makes contact with a contact pin 16 also in the base 18. The contact spring 6 is centrally mounted from the base by a member 17.

It will be seen that the number of parts in the structure of Figure 2 is comparatively large and the space it occupies is comparatively large. This is a serious defect, especially in wrist watches, preventing the attainment of a desirably small size and thickness. Moreover, because each switch has an appreciable stroke, i.e. has to be pressed in an appreciable way to operate it, exact and precise correction of time to a time signal, e.g. a broadcast time signal, is difficult and small errors in time correction are apt to occur. Moreover, in the case of a timepiece in which the manual input has to provide control for other purposes - e.g. in the case of a watch with a stop-watch facility - the number of switches necessary in the manual input is still further increased so that the defects and disadvantages of the type of construction illustrated by Figure 2 become more serious still.

According to this invention there is provided an electronic timepiece having a function selecting manual input portion comprising one or more touch switches as herein defined.

The term "touch switch" is employed in this specification with its customary meaning: that is to say it means a switch which, in contradistinction to one having a part which must be physically moved to operate the switch, can be operated by merely touching or nearly touching a fixed part thereof. The term "touch switch" is to some extent, a misnomer since, with many such switches, it is not essential actually to touch said fixed part with, for example, a finger, it being enough to bring the finger into close proximity to said fixed part.

However, the term "touch switch" is in general use for switches which are operable by touching or nearly touching a fixed part and is so used herein.

The timepiece may comprise touch switch means operable to select displayed time correction, to select the units of time to be corrected, and to correct the selected unitS.

Preferably the timepiece has an electronic digital display device and, in this case, may include a digital calculator wherein the same display device is used both for time display and calculation results display, the calculator employing a keyboard comprising touch switches each of a plurality of which is used for two functions in calculation, one being to put in a numeral and the other to put in an arithmetical function.

Preferably also each touch switch includes a touch plate connected in a MOS or C.MOS touch detecting circuit.

Referring to Figure 3 a touch switch replaces the push switch structure 4-5 of Figure 2. In Figure 3, 1 is the case of a wrist watch in which are secured metallic rods or tubes 22, 23 which are insulated from the case 1 by insulators 20 and 21. The rods or tubes 22, 23 are electrically connected to a wiring terminal of a circuit board 26 by springy connectors 24, 25 inside the case 1. As will be apparent, the parts in the construction shown in Figure 3 are very few in number and very simple mechanically.Moreover there are no moving parts or contacts, water-tightness is easily achieved, great reliability is attainable because there are no switch contact problems, and the construction in Figure 3 can be made as small in face area as is consistent with having reasonable separation of the rods or tubes 22 and 23, while, as regards thickness - an important matter in wrist watches - the necessary thickness of the structure of Figure 3 is very substantially less that that of the structure of Figure 2.

The touch switches used in carrying out this invention are operated by merely touching or nearly touching with the finger (27 in Figure 3) the appropriate fixed rod or tube 22 or 23.

Figure 4 shows the electrical circuitry of the touch switch arrangement of Figure 3. As will be seen, the touch switches are of the skin resistance detection type and there is a touch detection circuit using a C.MOS inverter and which detects when the part 22 or 23 is touched. A switch is switched on by touching the part 22 or 23 with the finger 27 which is at the same level as earth potential. The parts 22, 23 need not be rods or tubes but may be mere finger plates on the outer surface of the watch case and will be hereinafter referred to as "plates"or "touch plates".So long as the finger 27 does not touch a touch plate 22 (in order to shorten the description the operation will now be described only with reference to the plate 22 - the operation with regard to plate 23 is similar), the voltage level at point A is HIGH because of the voltage applied from VDD through the resistances R1 and R2 of which R1 is a high resistance. When the finger touches the touch plate, a resistance of value Rs, which is the skin resistance of the human body, is in effect connected between the plate 22 and earth and the voltage level at point A becomes Rs VnD R5 + R1 and if Rs < < R1 (as in practice it is) the voltage at A approximates to O V.The skin resistance Rs of different people is different but experiment shows that it is seldom as high as 10 MQ and usually considerably less. R1 is therefore in practice chosen at about 22 MQ.

The input side A of a C.MOS inverter 28 is connected to point A and the wave forms produced there are typified by line A in Figure 5 in which V55 represents the second (earthed) supply terminal potential. The lowered voltage part of line A of Figure 5 typifies the voltage at point A when plate 22 is 'touched, If there is only one C.MOS inverter 28 in the circuit a wave form as typified by curve B' in Figure 5 appears at point B, but by providing two more C.MOS inverters (not shown) before the point B, an improved, more squared up wave form as shown at B, of Figure 5, can be obtained at point B. 29 is an anti-chatter circuit comprising a pair of AND gates connected as shown, and a pulsed wave form of suitable frequency e.g. 32 Hz appears at S.This wave form, which is shown by line S of Figure 5 is synchronised with a 32 Hz square wave (top line in Figure 5). The period of a frequency of 32 Hz is longer than the period of any chatter or noise which can conceivably occur in practice. The wave form which appears at point C is shown by line C of Figure 5 and is applied to the data input terminal d of a delay type flip-flop 30 to the clock input terminal Ce of which is applied the wave form S. The delayed output from the flip-flop 30, appearing at D, is shown in line D of Figure 5.

In this way a chatter-free switch output (line D of Figure 5) is obtained by merely touching the plate 22 with the finger. The resistance R2 in Figure 4 is a protecting resistance for the C.MOS inverter 28 to prevent it from being damaged or destroyed by momentary abnormal voltage e.g. caused by static electricity. The resistance R2 should be about 1 MQ.

A C. MOS gate has an extremely high input impedance and being incorporated with a protection circuit constituted by a protection diode and a resistance, is well protected against damage by any abnormal voltage which may appear.

In the foregoing description of Figure 4, touch switch operation by making use of the human body skin resistance was assumed. However, switch operation by making use of hum induced in the human body can equally well be taken advantage of by the same circuit.

As will be understood, in this case the finger does not actually have to touch the fixed part 22 (or 23), it being sufficient to bring the finger near to it, i.e. to hold it "floating" close to it. However, to avoid unnecessary prolixity of terminology terms such as "touch", "touch plate" and " touch switch" are used in this specification and claims in accordance with the definition already given to include both actual touching contact and near touching contact, i.e. mere close proximity.

Figure 6 is a face view of an embodiment in which the invention is applied to an electronic wrist watch which incorporates an electronic calculator as well, the same display (here referenced 32) being used for both. The usual compact electronic table calculator has a keyboard formed of reed switches or contact spring switches but an electronic table calculator able to make calculations in accordance with the four rules of arithmetic (addition, subtraction, multiplication and division) requires a lot of keys such as input keys for registration, function keys for the four rules of arithmetic, a decimal point key, an equals key, a clearing key and so on. The more calculating functions to be provided for the larger the number of keys in the manual input becomes.It is not practical to miniaturize an electronic table calculator by reducing its dimensions proportionally until it will go into a wrist watch. Apart from anything else, if an electronic table calculator were miniaturized it could not be operated because the keys would be too small for the fingers to select.

Moreover a wrist watch is nearly always required to be waterproofed and it is not practically possible to waterproof a lot of mechanical switches while maintaining acceptably low cost and high reliability. However, the present invention can overcome these difficulties by using touch switches as will be described below.

In the combined electronic wrist watch and calculator wherein touch switches are used in the calculator keyboard, the touch switches are connected in touch detecting circuits as illustrated in Figure 4. 33 is a selecting switch, in the position of the crown of a watch and by means of which the functions of calculation and displayed time correction can be selected.

For time correction the crown 33 is operated to establish the circuitry required for displayed time correction and selection of the time unit to be corrected, and actual correction of the time unit selected is then effected by operation of the touch switches marked 1T1 and 2T2 respectively. Like other touch switches shown in Figure 6, each of these switches has two functions. When the "crown" switch is operated to permit calculation, the switches 1T1 and 2T2 serve as numeral input keys for the numerals 1 and 2 respectively.In order to decrease the number of input keys as much as possible most of the other calculator input key touch switches - as shown those for the calculator input touch switches 4, 5, 7, 8 and 9 - serve two functions, one of which is to put in the input numeral (4, 5, 7, 8 or 9) marked and the other of which is to put in an arithmetical function - as shown, subtract, divide, add, multiply or equals, respectively. By thus reducing the number of keys in the keyboard it is possible to accommodate it in the small space available and still have enough space between individual keys if they are made sufficiently small, to allow them to be actuated. A suitable size for the individual keyboard touch switches is about 2 mm diameter.As in the case of the previously described embodiment, the advantages of good reliability and watertightness are easily achieved because of the use of touch switches.

In the touch switch detecting circuit in Figure 4, when a touch plate is not touched the current consumed in the C.MOS inverters 28 amount practically to zero but a little current flows when a finger touches a touch plate. When a touch switch is used as the displayed time correcting switch of an electronic wrist watch, the current consumption is not of any great importance because of the comparatively few occasions, with an electronic watch, when time correction is required. When, however, the touch switches are used also in a calculator, they will be operated much more frequently and it is therefore much more important to reduce current consumption to a minimum.

Figure 7 shows a touch detecting circuit with three C.MOS stages. Similar references denote similar parts in Figures 7 and 4. In Figure 7 there is a three stage C.MOS inverter with three N-channel and three P-channel C.MOS elements as shown. This is used instead of one of the C.MOS inverters 28 in Figure 4. The points A and B in Figures 7 and 4 are, respectively, the same points i.e. the output at B is fed into an anti-chatter circuit (not shown in Figure 7) such as a circuit as shown at 29 of Figure 4.

Referring to Figure 7, when the input at A is at HIGH level, the N-channel MOS elements are ON and the output at B is at LOW level. In this condition, the current consumed in the inverter is extremely small, approximately to zero. When, however, the input at A is at LOW level, the P-channel MOS elements become ON and the output at B is at HIGH level. In this condition the input wave forms between the two power supply terminals VDD and Vss (see curve A in Figure 5) produce appreciable current consumption which, in practice, may reach several SuA.

This current can be substantially reduced by ensuring that the drain-source resistance is high when the MOS is switched ON. By making the resistance between source and drain of the C.MOS inverter high, for example, more than 1 MQ, when the C.MOS elements in the integrated circuit are being made (integrated circuit construction is assumed throughout) the consumption current in the ON condition can be brought down to 0.5 FA or less. The insertion of high resistance between each power supply terminal and the P-channel or N-channel MOS elements respectively connected thereto also results in substantial reduction in current consumption.

Figure 8 shows a modification of Figure 7 designed to decrease current consumption. The difference between Figure 8 and Figure 7 lies in the insertion, in Figure 8, of a P-channel MOS 36 and an N-channel MOS 37. The former has its drain-source circuit inserted in the supply connection to the terminal VDD and the latter is similarly inserted in the supply connection to the terminal Vss. The gates of the elements 36 and 37 are connected to a terminal 35 to which is applied a signal (obtained by means not shown in Figure 8) which is in synchronism with the signal at A but is of fixed predetermined pulse width so as to control the time during which the C.MOS inverter is ON. Consequently, when a finger touches the touch plate 22 it does not have to remain there during the time over which the wave form D of Figure 5 is at HIGH level. For example in the case of an electronic calculator, registration is made by a pulse width for two words, so that the signal is held at HIGH level for the shortest time accorded to the circuit to be used. At this time, since the circuit does not operate if the MOS connected io the source of a MOS in the inverter is not switched on before said MOS in the inverter is switched on, the P-channel MOS 36 and the N-channel MOS 37 must be such as to operate with a threshold voltage lower than the P-channel MOS and the N-channel MOS in the inverter.

When an electronic calculator is provided in a wrist watch, as in Figure 6, C.MOS elements of the lowest practical current consumption should be used in the circuits and liquid crystal display elements of the lowest practical current consumption should be used for the display. If this is done it is possible, even if there is only the one battery for both the watch and the calculator, to keep the current consumption low enough to be able to give the battery an acceptably long life guarantee.

Attention is directed to Patent 1 490 059 (Kabushiki Kaisha Daini Seikosha) which claims an electronic watch comprising a touch sensitive means mounted on a cover glass and a switching circuit connected to be operated by a change in an electrical property of the touch sensitive means when the latter is touched, the switching circuit conditioning operation of the electronic watch. We do not claim anything claimed in the said Patent 1 490 059 but, subject to this disclaimer, WHAT WE CLAIM IS: 1. An electronic timepiece having a function selecting manual input portion comprising one or more touch switches as herein defined.

2. A timepiece as claimed in claim 1 wherein the touch switches include switches for selecting displayed time correction, for selecting the units of time to be corrected, and for correcting the selected units.

3. A timepiece as claimed in claim 1 or 2 having an electronic digital display device.

4. A timepiece as claimed in claim 3 which also includes a digital calculator and wherein the same display device is used both for time display and calculation results display, the calculator employing a keyboard which also comprises touch switches each of a plurality of which is used for two functions in calculation, one being to put in a numeral and the other to put in an arithmetical function.

5. A timepiece as claimed in any of the preceding claims wherein each touch switch includes a touch plate connected in a MOS or C.MOS touch detecting circuit.

6. A timepiece as claimed in any of claims 1 to 5 and comprising at least one touch detecting circuit substantially as herein described with reference to Figure 4 or Figure 7 or Figure 8 of the accompanying drawings.

7. A timepiece as claimed in any of the preceding claims wherein the timepiece is a wrist watch.

8. Timepieces and combined timepieces and calculators in accordance with any preceding claims substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. elements of the lowest practical current consumption should be used in the circuits and liquid crystal display elements of the lowest practical current consumption should be used for the display. If this is done it is possible, even if there is only the one battery for both the watch and the calculator, to keep the current consumption low enough to be able to give the battery an acceptably long life guarantee. Attention is directed to Patent 1 490 059 (Kabushiki Kaisha Daini Seikosha) which claims an electronic watch comprising a touch sensitive means mounted on a cover glass and a switching circuit connected to be operated by a change in an electrical property of the touch sensitive means when the latter is touched, the switching circuit conditioning operation of the electronic watch. We do not claim anything claimed in the said Patent 1 490 059 but, subject to this disclaimer, WHAT WE CLAIM IS:

1. An electronic timepiece having a function selecting manual input portion comprising one or more touch switches as herein defined.

2. A timepiece as claimed in claim 1 wherein the touch switches include switches for selecting displayed time correction, for selecting the units of time to be corrected, and for correcting the selected units.

3. A timepiece as claimed in claim 1 or 2 having an electronic digital display device.

4. A timepiece as claimed in claim 3 which also includes a digital calculator and wherein the same display device is used both for time display and calculation results display, the calculator employing a keyboard which also comprises touch switches each of a plurality of which is used for two functions in calculation, one being to put in a numeral and the other to put in an arithmetical function.

5. A timepiece as claimed in any of the preceding claims wherein each touch switch includes a touch plate connected in a MOS or C.MOS touch detecting circuit.

6. A timepiece as claimed in any of claims 1 to 5 and comprising at least one touch detecting circuit substantially as herein described with reference to Figure 4 or Figure 7 or Figure 8 of the accompanying drawings.

7. A timepiece as claimed in any of the preceding claims wherein the timepiece is a wrist watch.

8. Timepieces and combined timepieces and calculators in accordance with any preceding claims substantially as herein described with reference to the accompanying drawings.