GB2077003A - Electronic timepiece - Google Patents

Abstract

In an electronic timepiece having an analog display device (44) provided at a substantially central area of the timepiece and an electro- optical display device (60) annularly disposed in a plane around the periphery of the analog display device (44), a wheel train for driving the analog display is supported between upper and lower wheel train bridges (154, 156) together with a stepping motor including a rotor (162), a circuit board (200) carries electronic components including an integrated circuit chip to drive the stepping motor and the electro-optical display and overlaps both those displays, and a dial (44a) for the analog display is disposed on one side of the circuit board (200) which is thus positioned between the dial (44a) and the lower wheel train bridge (156). The framework of the watch also includes a base plate (100) and an insulating plate (150). <IMAGE>

Description

SPECIFICATION Electronic timepiece BACKGROUND OF THE INVENTION This invention relates to an electronic time piece of the quartz-controlled oscillator type, which timepiece has a single movement that is equipped with both analog display means that relies upontime-indicating hands, and electro-optical display means such as a liquid crystal or electro-chromic display device.

Electronic timepieces of the quartz-con trolled oscillator type (referred to as quartz timepiece below) are inherently highly accu rate, stable and reliable. Such timepieces have gained popularity rapidly in recent years since their inherent advantages have been supple mented by improved design resulting from more compact and thinner arrangements, by a reduction in price and in the power consumed by stepping motors and integrated circuitry, and by prolonged battery lifetime realized by employing higher density batteries.

Quartz timepieces can be classified accord ing to the display means and the display format. To be specific, they can be broadly classified into timepieces having an analog display that relies upon time-indicating hands, timepieces having a digital display that explo its an electro-optical display device such as a liquid crystal or electrochromic display device, and timepieces having a dual display in which analog and digital display portions are com bined.

Although analog display timepieces may possess such advantages an attractive design, fashionable appearance and an easily readible display, they are inferior to digital timepieces in that the number of available functions is limited. As analog timepieces ordinarily incor porate a mechanical portion, design and relia bility suffer and costs rise owing to the com plex mechanisms which must be installed in such timepieces to realize automatic calendar and stop-watch functions through mechanical means. These and other functions pose no such problem in the fully electronic digital timepiece which allows functions to be added while a high reliability is maintained.This multifunction capacity is the major advantage ;of the digital timepiece, although the appear ance and readability of the display are inferior in comparison with the analog timepiece.

The dual display timepieces in which analog and digital display portions are combined fully exploit the advantages of both the analog and digital timepieces and are noteworthy because they seem to compensate for the shortcom ings encountered in these timepieces. Never theless, the dual display timepieces that have so far been proposed and partially marketed have little commercial appeal because there is insufficient correlation and harmony between the analog and digital displays.By way of example, in terms of external design, convention dual display timepieces have their analog and digital display portions merely arranged in parallel, or have one of the display portions disposed at a dominant position and the other at a subordinate position, with the arrangement being such that the subordinate display portion, which is very small in size, is seemingly attached to the dominant display portion. This diminishes the stylistic harmony between the two display portions and frequently results in a product having an odd appearance.

To be more specific, timepieces have been proposed in which an extremely small size digital display portion is installed in, say, the edge portion of a large size dial forming the analog display means. With a timepiece of this type a portion of the dial is cut away, resulting in a timepiece that not only has a poorer appearance as an analog watch but also a very small digital display portion which is difficult to read. In particular, a function display portion or the like, which gives an indication of such information as the display modes of the digital display portion, is quite small and difficult to read, or may even be impossible to provide. This makes it extremely difficult to use any additional functions which may be provided in connection with the digital display portion. The end result is that it is not possible to exploit even the advantages peculiar to both types of display.

The conventional dual display timepieces are deficient also in terms of the correlation between the display functions of both display portions. The state of the art is such that not even attempts have been made to expand variations in display format or to bring out novel display functions by arrangements in which the display portions utilize and supplement each other.

SUMMARY OF THE INVENTION According to the present invention, there is provided an electronic timepiece comprising: a circuit board mounting electronic components including an integrated circuit to provide first and second signals; analog display means including a stepping motor driven by said first signal; a wheel train for speed reducing and transmitting a mechanical output of said stepping motor; upper and lower wheel train bridges for supporting said wheel train; said analog display means being composed of hands driven by said wheel train, and a dial; and electro-optical display device driven by said second signal from said integrated circuit; said analog display means being disposed in approximately the center of the timepiece; said electro-optical display device being annularly disposed in a plane around a periphery of said analog display means; said circuit board being placed over a region of both said analog display means and said electro-optical display device; and said circuit board being disposed between said dial and said lower wheel train bridge arranged on the side of said dial.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram illustrating the structure of an electronic timepiece according to the present invention; Figure 2 is a top view of the electronic timepiece enclosed in a case; Figures 3 and 4 are plan views of the timepiece movement in the assembled state, Fig. 3 showing a bottom view and Fig. 4 a top view; Figures 5 through 13 are cross-sectional views each showing the timepiece in the assembled state, the view being taken along the lines A-A, B-B, C-C, D-D, E-E, F-F, G-G, I-I of Fig. 4, respectively; Figure 14 is a plan view of a circuitry supporting plate; Figure 15 is a plan view of an analog display mechanism arranged in block form; Figure 16 is a plan view of a hybrid circuit which mounts an IC and other electronic components; and Figures 17 and 18 show an annular liquid crystal display device, Fig. 1 7 being a plan view and Fig. 1 8 a cross-sectional view taken along the line J-J of Fig. 1 7.

DESCRIPTION OF THE PREFERRED EMBODI MENTS Fig. 1 is a block diagram which illustrates the structure of an electronic timepiece in accordance with the present invention. The electronic timepiece has a power source 10 which may comprise a high-density battery such as a button-shaped silver or lithium cell, an oscillator section 12, and a circuit section 14. The circuit section 14 comprises an oscillator and frequency divider circuit 16, the oscillator section 12 being composed of a miniature quartz oscillator and a miniature trimmer capacitor for adjusting the frequency of oscillation.The timepiece further includes a counter circuit (timekeeping counter) 1 8 for the timekeeping system of the timepiece, a counter circuit (alarm memory) 20 for the alarm system of the timepiece, a timer counter circuit 22, a stopwatch counter circuit 24, a coincidence detection circuit 26, a soundproducing circuit 28, a display changeover circuit 30, a decoder/driver circuit 32, an electro-mechanical transducer drive circuit 34, and an input control circuit 36. The circuit section 14 is accommodated on a single chip of a monolithic integrated circuit.The decoder/driver 32 drives annular electro-optical display device 38 which may comprise a liquid crystal display device or an electrochromic display device or the like, the former being adopted in the present embodiment owing to such considerations as cost, power consumption, lifetime and reliability. A stepping motor 40 is energized by the driver circuit 34 to drive an analog display means 44 through wheel train 42, which display means displays in analog fashion such time information as the hours and minutes. Numeral 46 denotes external operation means manipulated from outside the timepiece to changeover the display and to effect corrections and the like, the external operation means comprising analog and digital operating portions.The analog operation portion is operable to correct the analog display means 44, and the digital operation portion is operable, in principle, to changeover and correct the display of the electro-chemical display device 38. The external operation means 46 comprises five push-button switches (referred to as push-buttons below) 46a, 46b, 46c, 46d, 46e, push-buttons 46a through 46d constituting the digital operating portion, and the push-button 46e the analog operating portion. The external operation means 46 is arranged to deliver electrical signals to the input control circuit 36, thereby effecting the correction of the analog display means 44 as well as the correction and the display changeover of the electro-optical display device 38.

A so-called electronic-type hand-correcting system is adopted in the present embodiment, wherein the hands are advanced at normal or accelerated speeds by an arrangement in which the push-button 46e constituting the analog operating portion is adapted to generate a signal that is applied to the input control circuit 36, in response to which the driver circuit 34 is so controlled as to changeover the driving frequency of the stepping motor 40. Adopting this electronic hand-correcting system eliminates the need for a hand setting mechanism which includes a winding stem, clutch wheel, setting wheel, clutch lever and setting lever spring. This not only simplifies the timepiece but has the additional advantage of affording a greater degree of freedom for arranging the analog push-button 46e, the stepping motor 40, the wheel train 42 and other components.

Numeral 48 denotes a sound-generating device comprising a miniature speaker or a vibrator plate and piezoelectric element or the like. The sound-generating device 48 is driven by a signal from the sound-generating circuit 28 and issues an audible tone which serves as an alarm and as an hourly chime signal, or which may serve to indicate that the time set in a timer has expired.

The structure of an electronic timepiece embodying the invention will now be described in detail while referring to the drawings.

Fig. 2 is top view of an electronic timepiece according to the present invention. In Fig. 2, a crystal glass 51 is secured in a case band 52 through the intermediary of an L-shaped resin packing 54. A panel cover 56 is formed on the inner surface of the crystal glass 51 by a printing technique to achieve a proper balance for design purposes. Various information such as the functions associated with the push-buttons 46a through 46e are printed on a portion of the panel cover 56. The centrally disposed analog display means 44 and the digital employing the annular electro-optical display device 38 disposed along the outer peripheral portion of the analog display means 44 are seen within the display portion 58 which is surrounded by the panel cover 56.

The analog display means 44 is composed of a dial 44a, and hour hand 44b and a minute hand 44c and provides an analog display of the time through the usual method. The electro-optical display device 38 comprises a liquid crystal display device 60 as mentioned above, the digital display portion of the liquid crystal display device comprising an annular array of segments 62 formed along the peripheral portion of the analog display means 44, a function mark display portion 64 above the analog display, and a numeric display portion 66 consisting of bar-like segments arrayed below the analog display.The function mark display portion 64 includes a time mode mark "TIME" 64a, a calendar mode mark "DATE" 64b, an alarm function mark 64c, a chime signal mode mark 64d, a timer mode mark 64e, a stop-watch mode mark 64f, and a lap mark "LAP" 64g. The numeric display portion 66 includes a four-column alphanumeric display section 66a consisting of bar-shaped segments, an AM mark "AM 66b, a PM mark "PM" 66c. a colon 66d, a minutes mark ' t" 66e, a seconds mark "yV" 66f, and a hundredth-of-a-second mark "1/100" 66g.

The arrangement is such that the timepiece is operated and corrected by manipulating the push-buttons 46a through 46e.

The electronic timepiece of the present invention will now be described in connection with the method of operating the same, such as the method of selecting the desired function.

Push-button 46d is operated to select the mode. Modes are selected sequentially each time the push-button 46d is depressed, the sequence being the time mode, calendar mode, alarm mode, chime mode and stopwatch mode. Selecting the time mode excites the time mode mark 64a and causes the hour and minute of the current time to be displayed in the four-column alphanumeric display section 66a of the numeric display portion 66. The colon mark 66d is also excited in this case. Seconds are cumulatively displayed by excitation of one segment after another of the annularly arranged segments 62. The time mode mark 64a may not be the only mark excited in the function mark display portion 64; marks indicative of other functions which have been set may also be displayed.In other words, if the alarm function and chime function have also been placed in the set state (the state for issuing an audible tone), both the alarm mode mark 64c and the chime mode mark 64d will be in the excited state Furthermore, when the timer function and stop-watch function are in use (the timer counter circuit 22 and stop-watch are operE.t- ing), both the timer mode mark 643 and stopwatch mode mark 64f are in the excited state.

Thus, one can conveniently tell at a glance the selected function as well as the states of the other functions.

To correct the time, the push-button 46b is held depressed for from 0.75 to 1.0 second.

This places the timepiece in the correction state and flashes the cumulatively excited annular array of segments 62 that display the elapsed seconds information, the flashing condition indicating that the timepiece is in the seconds correction state. Depressing the pushbutton 46a under these conditions corrects the seconds display. To correct the minutes and hours information, the push-button 46b is depressed again to select the desired digit, and the push-button 46a is then depressed to correct that digit. Thus, the timepiece employs the so-called "select-and-set" method of correction. In order to shift the timepiece from the normal display of time to the seconds correction state, a timer is provided to actuate a switch once the push-button 46b has bee held depressed for the 0.75 to 1.0 second period.This is to prevent accidental operation of the switch should the push-button be depressed inadvertantly when the timepiece is in use. When a correction of the time entails a seconds correction only and not a minutes and hours correction, depressing the pushbutton 46c following completion of the seconds correction constrains the timepiece to return to the ordinary display state, thereby simplifying the correction procedure.

The seconds correction is a "zeroing" operation. In other words, when the correction is effected for a reading between 00 and 29 seconds, the actual seconds reading is discarded and replaced by 00 without a carry to the minutes digit. lf the correction is effected for a reading between 30 and 59 seconds, however, the seconds reading is raised to 00 with a carry of "1" to the minutes digit.

It has been mentioned above that the exter- nal operation means 46 comprises the analog operation portion and digital operation portion and that these are independent of each other in principle. However, the seconds correcticn is an interlocking operation since the analoc display is subjected to a seconds correction (although the analog display means 44 doe; not possess a second hand) by means of that digital operation portion. The analog display means 44 and the interlocked zeroing operc- tion of the digital seconds diplay will now b3 described.

Depressing the push-button 46b selects the seconds correction state, and depressing the push-button 46a applies a zeroing signal to the input control circuit 36. When this occurs, an analog output signal delivered to the stepping motor 40 is either interrupted or accelerated. To be more specific, if the zeroing signal arrives when the content of a seconds counter in the time counter circuit 22 is between 0 and 29, the timepiece is judged to be running fast so that the analog output signal is interrupted for a period of time equivalent to the count in the seconds counter. In this case the digital display is restored to 00 without a carry to the minutes digit, as described above.

When the content of the seconds counter is between 30 and 59 seconds, the timepiece is judged to be running slow so that the analog signal is delivered to the stepping motor 40 at a faster rate to make up for the amount of time short of 60 seconds. The digital display behaves as in the manner described above. If the analog and digital displays are in exact agreement when in the initially set state, the seconds zeroing operation will not give rise to any descrepancy between the two displays even if the operation is repeated any number of times.

Except for the seconds correction, the analog display means 44 is corrected, entirely independently of the digital display, by the push-button 46e, and this holds regardless of the function which has been selected for the digital display. An electronic correction system is adopted for correcting the analog display means 44 in the present embodiment, wherein each single depression of the pushbutton 46e sends a single pulse in an analog output signal to the electromechanical transducing means 40 to advance the minute hand 44c by an amount equivalent to 20 seconds.

If the push-button 46e is held depressed for from 0.75 to 1.0 second, however, the pulses forming the analog output signal are applied to the transducing means at a rapid rate of 32Hz (32 pulses per second) to correct both the minute hand 44c and hour hand 44b.

Next, a description will be has as to the method of initially setting the analog display means 44 and the digital display.

The electronic timepiece of the present invention is so adapted that the analog display means 44 and digital display are corrected independently of each other with the exception of the seconds correction, as set forth above. To bring the analog display and digital display into coincidence, the analog display means 44 is set to 12:00 with particular care being exercised in setting the minute hand 44c, then the push-buttons 46a, 46b, 46c, 46d, are depressed simultaneously to close the associated switches. This places the digital display in the reset state, the display reading 12:00 which is in agreement with the analog display. To set the seconds digits precisely, push-buttons 46b, 46a are utilized to restore the seconds display to zero. This will assure exact coincidence because the seconds correction is linked to both the analog and digital displays.An alternative method is to set the digital display to a standard time signal and then bring the hour hand 44b and minute hand 44c into agreement with the digital display by utilizing the push-button 46e.

Next, depressing the push-button 46d selects the calendar mode so that the display is switched over from the time mode. This excites the calendar mode mark 64b and turns off all the other function marks. However, the displays for the alarm and other functions can still be selected in the manner described above. The annular array of segments 62 continue to provide a seconds display in the same manner as when the time mode is active. In the numeric display portion 66 the date and day of the week are displayed by the alphanumeric display section 66a, the first two places showing the date and the second two the day; all other marks such as the mark 66b are turned off. The information displayed in the numeric display portion 66 is corrected by depressing the push-button 46a after the push-button 46b has been manipulated to select the desired portions of the display, as described above.The day of the week, date, month and year are corrected in the order mentioned. The calendar function is fully automatic in the present embodiment so that, once set, it need not be corrected until the battery is replaced.

Depressing the push-button 46d again selects the alarm mode, causing the alarm mode mark 64c to flash and to deactivate all other marks on the function mark display portion 64. The annular array of segments 62 continue to provide a seconds display in the same manner as when the time mode is active. The numeric display portion 66 shows the set alarm time if the alarm function is in the set state (the state for issuing the audible tone), of displays the word "OFF", employing three columns of the alphanumeric display section 66a, if the alarm function has not been set.

The alarm function ordinarily is or is not placed in the set state by manipulating the push-button 46a. The set alarm time is corrected by the push-button 46a after the desired digits have been selected by push-button 46b, as set forth above.

Depressing push-button 46d again selects the chime mode, causing only the chime mode mark 64d to flash on the function mark display portion 64. The annular array of segments 62 continue to provide a seconds display. The alphanumeric display section 66a of the numeric display portion 66 displays either the word "ON" or "OFF", indicating whether oronot this function is in the set state, These states are switched between by manipulating the push-button 46a.

Depressing push-button 46d now selects the timer mode, causing only the timer mode mark 64e to flash on the function mark display portion 64. The alphanumeric display section 66a of the numeric display portion 66 displays the hour and minute digits of the set time, and the annular array of segments 62 provide a seconds display which is decremented in the counter-clockwise direction.

The timer setting is corrected by the pushbutton 46a after the desired digits have been selected by the push-button 46b. The time function is started and stopped by the pushbutton 46c. When the timer is counting down, depressing push-button 46a restores the timer display to the initially set state. In other words, the timepiece is provided with a so-called flyback function for the timer mode.

Depressing the push-button 46d again selects the stop-watch mode, causing only the stop-watch mode mark 64f to flash on the function mark display portion 64. The minutes mark 66e and the seconds mark 66f are excited in the numeric display portion 66, and the alphanumeric display section 66a displays the minutes and seconds information. If the push-button 46b is held depressed while the stopwatch is operating, the minutes mark 66e and-seconds mark 66f will be deactivated, the one-hundredth-of-a-second mark 66g will be excited, and the two digits on the right-hand side of the alphanumeric display section 66a will show the elapsed time to the hundredth of a second, the changeover to this display continuing for as long as the push-button 46b is held depressed. The push-button 46c is depressed to start and stop the stop-watch, and lap/reset is effected by depressing pushbutton 46a.The annular array of segments 62 are cumultively excited one at a time each 1/100 of a second as long as the stop;watch counter circuit 24 is counting. All of the segments will be in the excited state in the interval extending from 60/100 to 79/100 of a second, and then they will all be deactivated in the interval extending from 80/100 to 100/100 of a second, thus presenting a revolving scanning display. Hence, the arrangement is such as to provide a distinctive format for display operation.

The electronic timepiece according to the present invention is equipped with the soundgenerating device 48 that is driven by the output signal of the sound-generating circuit 28 in order to issue an audible tone. The arrangement is such that the audible tone is issued when the set time has been reached in the case of the alarm function, when the chime function has been set, when the time to which the timer has been set has run out (i.e., remaining time is zero), and when the stopwatch and timer functions are started and stopped. When the sound-generating circuit 28 delivers an output signal, the arrangement is such that adjacent segments in the annular array 62 will flash alternatingly in pairs. Thus, the invention adopts a distinctive display format which provides a timepiece having a high commercial value.

Reference will now be had to the drawings from Fig. 3 onward two describe the assembly procedure with particular regard to the structural features of the invention. Figs. 3 and 4 are plan views showing the timepiece in the assembled state, Fig. 3 being a top view (showing the display side), and Fig. 4 being a bottom view (showing the back cover side of the case). Figs. 5 through 1 3 are crosssectional views showing the timepiece in the assembled State, these views being taken along the lines A-A through I-I of Fig. 4. The phantom lines in Figs. through 1 3 denote the members constituting the watch case.

Numeral 100 denotes a base plate which is made of metal. As illustrated in Fig. 14, the base plate 100 is a unitary body having large cut-out portions 101, 102 in the central and right-hand sections thereof, an access hole 103 for a crystal vibrator 130, a hole 104 for allowing adjustment of a trimmer capacitor 132, an access hole 105 for access to a booster coil 1 34 of the sound-generating device 48, an access hole 106 for a coil-shaped connector spring 1 36 for applying signals to the sound-generating device 48, and various other holes. Implanted in the base plate 100 are hybrid circuit tubes 107, 108, 109 which are distributed adjacent the central portion of the plate. An access hole 110 and a cut-out portion 111 which permit access to dial fastening shafts 138, 1 40 for securing a dial 44a.Provided on the peripheral portion of the base plate 100 are five spring members 112, 113, 114, 115 and 116, the tips of which abut against stoppers 117, 118, 119, 120, 121 that are provided on the supporting plate 100 proper. The centrally located cut-out portion 101 permits access to an analog display mechanism which includes the stepping motor 40 and the wheel train 42. The cut-out portion 102 at the upper right-hand portion of the plate permits access to a battery 1 44.

Here the tip 1 22a of a side pressing spying portion 1 22 contacts the side of the battery 1 44 to apply pressure thereto. A protuberance 1 23 is provided on the side of the cut-out 102 -which is opposite the spring portion122, and is adapted to contact the side of the battery 144. The base plate 100 constitutes the principal foundation member for the timepiece movement.

Numeral 1 50 denotes a main plate serving as a circuit supporting pedestal comprising a synthetic resin having excellent moldability and strength, such as polyacetal, the pedestal cooperating with the base plate 100 in forming the foundation member for the timepiece movement. The dial fastening shafts 138, 1 40 are rotatably mounted on the main plate 1 50 from the upper side.In addition to a wheel train accommodating recess 150a formed at its center, the main plate 1 50 is formed to include an access hole 150b for the crystal vibrator 130, a hole for manipulating the trimmer capacitor 132, an access hole 150c for the booster coil 134, an access hole 150d giving access to a transistor 1 52 for the sound-generating device 48, and a guiding hole 150e for the connector spring 1 36.

Formed in the upper side of the main plate 150 is a battery receiving compartment 150f for the battery 1 44, and in the lower side a compartment for receiving the electronic components of a hybrid circuit which will be described below.

Numeral 70 designates a battery receiving spring which is secured in the main plate 150 by pressing down a positioning portion 70a.

In addition to the positioning portion 70a, the battery receiving spring 70 comprises a contact spring portion 70b which contacts the battery 144, and a contacting spring portion70c which comes into contact with a conductive pattern provided on a circuit board to be described below. The battery receiving spring 70 is so designed that the force exerted by the contact spring portion 70b is several times greater that that exerted by the contacting spring portion 70c, the reason being to prevent improper conduction if the battery 1 44 should leak.

The main plate 150 is further provided with three positioning holes 150g, 150h, 1 SO adjacent the central portion thereof.

The main plate 150 having the above structure is positioned on and unified with the base plate 100 described above by means of the hybrid tubes 107, 108, 109. The next unit installed is the analog display mechanism arranged in the form of a block including such components as a stepping motor 40 and a speed reduction wheel train 1 70.

Reference will now be had to Figs. 7, 8 and 15 to describe the analog display mechanism.

Numeral 1 54 denotes a flat upper wheel train plate (referred to as an upper bridge hereafter) having three supporting columns 154a, 1 64b, 154c, two tubes 154d, 1 54e and a bearing 154f secured thereto. Formed on the wheel train bridge 1 54 are bearing portions 154g, 154h, 1 S4i of the speed reduction wheel train 1 70. Numeral 1 56 denotes a flat lower wheel train plate (referred to a lower bridge hereafter) having an implanted center pipe 156a and a bearing 156b which is secured thereto.The lower bridge 1 56 also is formed to include bearing portions 156c, 1 56d similar to those on the upper bridge 1 54. The planar configuration of the lower bridge 1 56 is approximately the same as that of the upper bridge 1 54 but has three portions that project outwardly from the upper bridge, the projecting portions having respective holes 156e, 156f, 1 56g for positioning and assemblage purposes.

The stepping motor 40 comprises a stator 160, rotor 1 62 and drive coil 1 64. The rotor 1 62 has a unitary structure composed of a rotor pinion 1 62a a portion of which has a gear, a rotor magnet 1 62b comprising a permanent magnet, and a rotor seating member 162c. The drive coil 1 64 has a spacer 1 64b and a coil terminal board 1 64c bonded on a coil winding core 1 64a to form a unitary body therewith, and a conductor 1 64e which is wound on the core 1 64a following the attachment of a winding frame 164d.Each end of the conductor 1 64a is soldered to a conductive pattern formed on the coil terminal board 1 64c and serves as a terminal.

Numeral 1 72 denotes a third wheel forming a portion of the speed reduction wheel train 1 70 and comprising a unitary body consisting of a third wheel gear 1 72a meshing with the rotor pinion 162a, and a third wheel pinion 172b. Numeral 1 74 denotes a center wheel comprising a center wheel gear 1 74a meshing with the third wheel pinion 172b, and a center wheel pinion 174b. The center wheel pinion 1 74b has two large diameter portions serving as guide portions 174c, 174d.Numeral 1 76 denotes a minute wheel component comprising a minute wheel 1 76a meshing with the center wheel pinion 174b, and a minute wheel pinion 1 76b having tenons at each end to iighten the load and improve transmission efficiency. Numeral 1 78 denotes an hour wheel comprising an hour wheel gear 1 78a which meshes with the minute wheel pinion 17bob, and an hour hand arbor 1 78b having a guide portion 1 78c in the form of a large diameter portion adjacent one end thereof. Numeral 1 80 denotes an hour wheel friction spring.

The rotor 162, third wheel 172, center wheel 174, minute wheel 1 76 and hour wheel 1 78 are held between the upper and lower bridges 154, 156, with the rotor 162, third wheel 1 72 and minute wheel 1 76 being directly supported by the bearings 154f, 156b and bearing portions 1 54g, 156c, 1 54i and 1 56d located on the upper and lower bridges. The center wheel 1 74 and hour wheel 1 78 are supported between the upper bridge 1 54 and lower bridge 156 through the hour wheel friction spring 180, the hourwheel 178 being rotatably supported at the guide portions of the center wheel pinion 174b, with the guide portion 1 78c of the hour hand arbor 178b being guided rotatably at the inner periphery of the center pipe 156a. To be more specific, the center wheel 174 and hour wheel 178 are journalled between the bearing portion 154h on the upper bridge 154 and the inner periphery of the center pipe 156a, and they guide each other.

The upper and lower bridges 154, 156 are spaced apart and mutually.positioned by the three supporting columns 154a, 154b, 154c, the lower bridge 156 being secured by screws 182, 184.

The stator 1 60 is positioned by the two tubes or columns 154d, 1 54e and is secured by a screw 1 86 to the upper bridge 1 54 together with the drive coil 1 64. This completes the analog display mechanism although, in the present state, the supporting column 154c and the side of the coil terminal board 1 64c of the drive coil 1 64 have not as yet been fastened by a screw.

In operation, an analog output signal from the drive circuit 34 is applied to the drive coil 1 64 that responds by generating a magnetic field to excite the stator 1 60. The rotor 1 62 is rotated due to the magnetic attraction and repulsion interaction between the stator 1 60 and rotor magnet 162b. The rotational displacement of rotor 1 62 is shifted down in being transmitted to the third wheel 1 72 and center wheel 1 74 so that the latter revolves once per hour. As a result, the time in minutes is displayed in usual fashion by the minute hand 44c, which constitutes a portion of the analog display means, mounted on the end of the center wheel pinion 174b.The rotational displacement of the center wheel 1 74 is shifted down in being transmitted to the minute wheel 1 76 and hour wheel 1 78 so that the latter makes one revolution every 1 2 hours. Thus, the time in hours is indicated in usual fashion by the hour hand 44b which is mounted on the end of the hour hand shaft 178b. The analog display adopted in the present embodiment comprises the two hands 44b, 44c, namely the hour hand 44b and the minute hand 44c, the arrangement being such that the hands are advanced every 20 seconds.

The characterizing features of the analog display mechanism described above are as follows. First, owing to the adoption of the electronic correction system mentioned above, it is possible to dispense with such components of the ordinary hand setting mechanism as a winding stem, setting lever, clutch lever, clutch wheel an-d setting wheel, the intent being to reduce the number of parts and to simplify the mechanism. Further, since the speed reduction wheel train 1 70 is embraced and supported between the flat upper and lower bridges 154, 1 56 the arrangement can be reduced in cost, size and thickness and unified into a single block.In addition, the center wheel 1 74 and hour wheel 1 78 guide each other and are axially supported between the upper bridge 1 54 and the center pipe 156a. This lengthens the distance over which the shafts are supported to minimize tilting of the center and hour wheels 174, 1 78. This reduces deviation at the tips of the hour and minute hands 44b, 44c, so that the timepiece can be reduced in thickness by narrowing the clearance between the hands. No slip mechanism need be provided on the center wheel 1 74 so machining of parts, adjustment of the assembly and parts management are great y simplified.

Installation of the aforesaid analog display y mechanism is accomplished simply by aligning the holes 156e, 156f, 156g provided in the lower bridge 1 56 with the hyt rid tubes 109, 1 08, 1 07, respectively, and th 3n by placing the mechanism on the main pla e 150.

Next, an insulating sheet 1 90 is installec.

The insulating sheet 1 90 consists of a synthetic resin such as polyester and is shapec to extend over the lower bridge 1 56 and a portion of the battery 144, while being pro: i- tioned by the hybrid tubes 107, 108. The insulating sheet 1 90 is provided with peep holes at those locations thereof corresponding to the bearing 1 56b and bearing portions 156c, 156d of the lower bridge 156, and with access holes for the center pipe 1 spa and screws 182, 184.

The next item installed is a hybrid circuit composed of such electronic components as an IC mounted on a circuit board. A plan view of the hybrid circuit is shown in Fig. 16, in which numeral 200 denotes a circuit board composed of copper foil bonded to a glass epoxy substrate, the foil being photoetched in the usual manner to form a conductive pattern 202 on the substrate.The circuit board 20) is formed to include an access hole 204 fo the center pipe 156a, positioning holes 20 3, 208, 210, an access hole 212 for the drive coil 164, access holes 214-, 216 for the heads of screws 182, 184, and access hole 1 28 for the trimmer capacitor 132, and ac cess hole 220 for the booster coil 134, peep holes 222, 224, 226, for the bearing 156b of the rotor 1 62 and for the bearing portior s 1 S6c, 156d of the third wheel 172 and minute wheel 1 76, and access holes 228, 230 for the legs 142a, 1 42b of the dial 4L a.

The outer periphery of the circuit board 20r) has six projecting portions 232, 234, 236, 238, 240 and 242, and is provided with side electrode portions 244, 246, 248, 250, 2.;2, these being obtained by forming electricallL conductive portions on the side walls of five indentations 254, 256, 258, 260 and 262.

The circuit board 200 is provided with a solder resist by a printing technique, the res ist extending over the entire conductive patterr 202 with the exception of portions thereof.

Numeral 202a denotes a cathode pattern forming a portion of the conductive pattern 202, and 202b, 202c denote analog output patterns provided at the periphery of a hole 268 in a concentric relationship therewith.

Numeral 202d designates an inspection paltern which is used for inspecting the condit on of analog output signals following completic n of the timepiece module, and numeral 202 denotes a bonding portion pattern. A displa output pattern 202f for applying signals to the liquid crystal display device 60 is provic ed on the reverse side of the circuit board 200, the pattern being divided into an upper row and a lower row. The concentrically formed patterns 2029 about the peripheries of the positioning holes 206, 208, 210 and the hole 270 are anode patterns.

An IC 203 is secured to the circuit board 200 and a wire 201 interconnects the pattern 202e and the electrode pad of the IC 203. A circuit encapsulation frame 205 comprises an encapsulation portion 205a for the IC 203 and a positioning portion 205b for the crystal vibrator 130, the frame being positioned on the circuit board 200 by bosses 205c, 205d.

The circuit encapsulation frame 205 is bonded to the circuit board 200 and the encapsulation portion thereof is filled with a potting resin 207. The latter is intended to make the IC 203 more resistants to the atmo sphere and to mechanically protect the wire 201.

The crystal vibrator 130, trimmer capacitor -132, booster coil 134 and transistor 1 52 are mounted on the circuit board by soldering them to predetermined portions of the con ductive pattern 202. A resistor 209 and a capacitor 211 for the sound-generating device A48 similarly mounted by soldering them into position. Also mounted by soldering are ca pacitors 213, 215 used to construct a booster circuit for driving the liquid crystal display device 60. It will be obvious from Fig. 1 6 that the IC 203 is mounted at the lower right portion of the circuit board 200, while the other electronic components are mounted in a group adjacent the periphery of the circuit board.

In electronic timepieces equipped with a liquid crystal display device 60, the electrodes for supplying driving signals to the liquid crystal display device generally occupy 70 to 80% of the total number of electrodes pro vided on the IC 203, so it is critical that the conductive pattern for the driving signals be arranged in the most suitable and efficient manner. In the present embodiment the bat tery 144 and IC 203 have been disposed at the locations best suited for the pattern ar rangement in view of the above point.

The aforesaid hybrid circuit is placed on the main plate 150, and secured by three screws 216, 218, 220, upon aligning the postioning holes 206, 208, 210 with the circuit tuses 107, 108, 109, respectively. At this tire screws 272, 274 are passed through the holes 268, 270 in the circuit board 200 and are tightened to secure the supporting column 154c of the upper bridge 1 54 and the portion of the coil terminal board 1 64c of the drive coil 1 64. Tightening the three screws 276 through 280 brings the base plate 100, main plate 150, lower bridge 156, insulating sheet 1 90 and circuit board 200 tightly together into the form of a unitary body.The screw 272 secures the upper and lower bridges 154, 1 56 together through the insulating sheet 1 90 and circuit board 200, the arrangement being such as to ensure a stable gap between the upper and lower bridges 154, 1 56 and to prevent their deformation by causing the force, which is exerted upon the upper bridge 1 54 when the hour hand 44b and minute hand 44c are attached, to be partially absorbed not only by the lower bridge 1 56 but by the circuit board 200 as well.In addition, the screw 274 brings the" stator 1 60 and the coil winding core 1 64a tightly together to prevent an increase in the magnetic resistance, and brings the analog output patterns 202b, 202c of the circuit board 200 into close contact with the coil terminal board 1 64c to achieve good electrical interconnection. In accordance with the present embodiment, the spacer 1 64b is interposed between the coil terminal board 1 64c and the coil winding core 164a. Selecting a suitable thickness for the spacer 1 64b allows the drive coil 1 64 and the circuit board 200 to be set at the same level, providing a structure with a great deal of freedom for arrangement in the thickness direction.As the spacer 1 64b is adopted a synthetic resin exhibiting a high degree of hardness but little creep and deterioration with age, thereby affording a simple structure which is highly reliable.

The stepping motor 40, speed reduction gear wheel train 1 70 and upper bridge 1 54 of the analog display mechanism are accommodated in the access hole of the main plate 1 50 and the cut-out portion 101 of the base plate 100, in which state the upper bridge 1 54 and base plate 100 are approximately flush. Further, the planar clearance between the base plate 100 and the drive coil 1 64 and stator 1 60 is greater that the planar clearance between it and the upper bridge 1 54. This is to prevent a deterioration in the characteristics of the stepping motor 40 owing to leakage of flux from the drive coil 1 64 and stator 160, the reason being that the base plate 100 comprises a magnetic body.

The liquid crystal display device 60 is installed next. Fig. 1 7 illustrates a plan view of the device, and Fig. 1 8 a cross-sectional view taken along the line J-J. Numeral 410 denotes an upper transparent plate the entire bottom surface of which is coated with an electrically conductive thin film consisting mainly of indium oxide (In203) or tin oxide (SnO2), which coating is then photoetched by a usual technique to form a pattern serving as segment electrodes 411. Numeral 41 2 denotes a lower transparent plate on whose top surface are formed common electrodes 41 3 through the same method described above in connection with the upper plate 410.A method for the slant evaporation of SiO or a rubbing technique is employed to form an orientation layer on the sides of the upper and lower transparent plates 410, 41 2 that bear the electrodes, the layers so formed having mutually perpendicular orientations. Numerals 414, 415 denotes sealing layers comprising glass of a low melting point, epoxy resin or the like the sealing layers being adapted to establish a clearance of about 0.08 millimeter between the upper and lower transparent plates 410, 412. Numeral 416 denotes a liquid crystal material. Polarizes 417, 418 having mutually perpendicular directions of polarization are provided, polarizer 41 7 being bonded to the upper transparent plate 410 and polarizer 418 to the lower transparent plate 412. Thus is constructed a liquid crystal cell 60.The liquid crystal display device 60 is completed by disposing a reflector 41 9 below the bottom side of the lower transparent plate 41 2 of the liquid crystal cell 60.

The liquid crystal display device 60 in the present embodiment has an annular configu ration the central portion of which has an opening 420 in the shape of a square hole.

Sixty of the annular array of segments 62 are arranged along the peripheral portion of the opening 420, such marks as the time mode mark 64a, calendar mode mark 64b and alarm mode mark 64e are provided along the top of the opening, and the four-column al phanumeric display section 66a, AM and PM marks 66b, 66c and the like are provided along the bottom.

The square opening 420 is formed in the following manner. First, the liquid crystal ma terial 41 6 is sealed in the clearance between the upper and lower transparent plates 410, 41 2. Next, a mask having a window of ap proximately the same shape as the opening 420 is employed to mask the resulting cell which is then subjected to liquid honing to form the opening. Liquid honing is not the only method which may be used to work the opening 420. Others include ultrasonic ma chining and dry honing, although the liquid honing method has been adopted in the pre sent embodiment in view of machining time, precision, operability and machining cost as determined upon comparing the above meth ods.While the opening 420 may be worked to a dimentional precision of within + 0. 150 millimeter by the liquid honing method alone, the periphery of the opening should be shaped by a grinding method as well where a particularly high precision is required. Com a binding the grinding method with the liquid honing method enables a dimensional preci sion to within + 0.02 millimeter.

The polarizers 417, 41 8 are bonded into place following the formation of the opening 420.

Owing to the existence of the opening 420, the liquid crystal display device of the present embodiment has only one-half to one-third the strength of the usual square or octagonal display device, a fact which requires that special attention be paid to a retaining structure for the device and to the arrangement of the battery 144 and other component parts.

Accordingly, scrupulous care has been taken in investigating breakage mode and breakage strength by applying static pressures and loads to a liquid crystal display device actually provided with an opening. The result is the arrangement of parts adopted in the present embodiment, as well as a retaining structure which will be described below.

To install the liquid crystal display device 60, the reflector 41 9 is placed upon the circuit board 200 to begin the procedure. The reflector 41 9 is approximately positioned by six projections 150j, 150k, 150m, 150n, 150p, 1 50q which are provided on the main plate 1 50 and which pass through the circuit board 200. Next, a piece of connective rubber 31 is placed upon the circuit board 200, the rubber having a rectangular section and a width which is narrower than in conventional timepieces. Owing to this structure the rubber is likely to meander or collapse when the timepiece is assembled, and there is a strong possibility of a poor electrical connection when the liquid crystal cell is installed. This problem may be prevented in the following manner.Longitudinal positioning of the connective rubber 31 is accomplished by pairs of projections 150r, 150r' and 150s, 150s', and collapse in the width direction is prevented by the six aforesaid projections 1 50j, 150k, 150m, 150n, 150p, 150q, by islandshaped projections 1 501. 1 501', and by the inner walls of six projection-like guide portions 150t, 150t', 150u, 150u', 150v, 150v' provided near the circumference of the main plate or circuitry supporting pedestal 150, the guide portions serving also to guide the rubber 31.It is preferred that the height of the six projections 150j through 150q be as large as possible in order to prevent collapse of the connective rubber 31, but this would cause the projections to overlap the polarizer 418, whereas it is required that a gap be maintained between the projections and the polarizer. Accordingly, the ends of the six projections 150j through 1 50q are shaped as shown in Figs. 10 and 13, where one-third of the projection on the side facing the rubber 31 is elongated while the remaining portion thereof is shortened.

Next, the liquid crystal display cell 60 is put in place. At such time the cell is positioned by the six projection-like guide portions 150t through 150v' and is fixed by a cell holding frame 320. The holding frame 320 comprises a synthetic resin, such as polyacetal, having excellent moldability and strength, and is provided with a picture-frame shaped holding portion 3201, and with six hook portions 3202, 3203, 3204, 3205, 3206 and 3207 that serve to secure the cell, the hook portions 3202 through 3207 being provided at posi tions which correspond to those of the projection-like guide portions 150t through 150v'.

The installation of the liquid crystal cell holding frame 320 proceeds as follows. The projection-like guide portions 150t through 150v' are passed through and positioned in guide windows 3208, 3209, 3210, 3211, 3212, 3213 provided in the cell holding frame 320. Depressing the cell holding frame 320 in this condition causes the hook portions 3202 through 3207 to bend outwardly owing to their resilience as they slide on the outer wall surfaces of the projection-like guide portions T50t through 150v', the hook portions 3202 through 3207 eventually engaging with and locking six indented step portions 1229 through 1 234 provided on the peripheral portion of the supporting pedestal 1 50 at the top thereof. The structure is shown in Fig. 10.

Thus, as described above, the liquid crystal display cell 60 is supported along its entire peripheral portion by the cell holding frame 320 consisting of a synthetic resin arranged in the form of a picture frame. This configuration is extremely effective in preventing breakage of the cell 60 due to impact. Moreover, adopting the cell holding frame 320 of the described shape greatly narrows the width from the inner edge of the panel cover 1004 to the outer periphery of the module, thereby contributing to an improved design.

Numeral 330 denotes a device cover which is made of a synthetic resin and which, in addition to a step 3301 formed about the entire outer peripheral portion thereof, is provided with an access hole 3302 for the battery 144, an access hole 3303 for the analog display mechanism, an adjustment hole 3304 for the trimmer capacitor 1 32, an access hole 3305 for the connector spring 136, a speed measurement terminal hole 3306, access portions 3307, 3308 for the dial fastening shafts 151, 153, peep holes 3309, 3310 for the bearing portions 154h, 154i of the center wheel 1 74 and minute wheel 176, an oscillation inspection terminal hole 3311, and the like.The device cover proper is formed to include two tosses which, although not illustrated, are pressed into holes (not shown) formed in the circuitry supporting pedestal 150, whereby the device cover 330 is secured. These portions are designed so as to fit together loosely, enabling the device cover 330 to be removed with little effort.

The above step completes the assemblage of the timepiece module. The description will now be directed toward the structure for supplying power and the structure of the switch portions.

The tip 1 22a of the side-pressing spring portion 122 of the base plate 100 and the protuberance 1 23 thereof are in constant contact with the side wall of the battery 144. As a result, the base plate 100, and the hybrid circuit tubes 107, 108, 109 implanted therein, have the same polarity as the anode side of the battery. Meanwhile, the conductive patterns 202g around the peripheries of the positioning holes 206, 208, 210 in the circuit board 200 are connected with the electrodes on the anode side of the IC 203.Accordingly, when the hybrid circuit is installed and the screws 276, 278, 280 are tightened from above the circuit board 2000, the heads of the screws 276, 278, 280 are brought into sure contact with the conductive patterns 202g, and the screws come into engaging contact with the hybrid circuit tubes 107, 108, 109 at the threaded portions thereof.

Hence, the anode side extends from the side wall of the battery 1 44 to the conductive patterns 202g as connected through the tip 1 22a of the side-pressing spring portion, the circuitry supporting plate 100, the hybrid circuit tubes 107, 108, 109, and the screws 276, 278, 280. The components of the cathode polarity will be described next.

The contact spring portion 70b of the battery receiving spring 70 is in contact with the bottom of the battery 144, and the contacting spring portion 70c of the spring 70 is in contact with the conductive pattern 202a at the cathode side of the circuit board 200.

Since the conductive pattern 202a is connected with the electrodes on the cathode side of the IC 203 by the conductive pattern 202a, the bottom portion of the battery 144 and the IC 203 are interconnected through the battery receiving spring 70. The anode side is connected at three points as described above and therefore has an enhanced reliability. In the case of the cathode side, the contact spring portion 70b of the battery receiving spring 70 is bent upwardly and the contacting spring portion 70c thereof is bent downwardly. Hence, when the battery 144 is inserted, the contact spring portion 70b is urged downwardly and the contacting spring portion 70c attempts to move in the same direction as well.Moreover, since the circuit board 200 is disposed beneath the battery receiving spring 70, the contact between the contacting spring portion 70c and the conductive pattern 202a on the circuit board 200 is maintained at all times. This greatly enhances the reliability of the electrical interconnectiòn among the components constituting the cathode side. The structure for supplying power as just described is shown in Figs. 5 and 6.

Reference will now be had to Fig. 5 to describe the structure of the switch portions.

The push-button 46e constituting the external operation means 46 is movable in the axial direction thereof within a case pipe 280 secured in the case band 52. Fitted adjacent the inner end of the push-button 46e is an E-ring which prevents the push-button from falling out of the case, and mounted on the central portion of the push-button 46e is an O-ring 46e"' which prevents contaminants such as water and d Jst from invading the timepiece through the gap between the case pipe 280 and the pus7-button 46e. Formed on the spring portion 11 3 of the base plate 100 is a contact portion 11 3a which is formed at the same level as the push-button 46e so that it may engage with the tip 46e" of the pushbutton.The contact portion 11 3a is formed at the same level as the circuit board 200 as well.

When the push-button 46e is depressed, the tip 46e" thereof abuts against the contact portion 11 3a which is deflected and brought into contact with the aformentioned side electrode portio1 244 of the circuit board 200, thereby closing the switch. Removing one's finger from he push-button 46e allows the latter to be W estored under the force exerted by the spring portion 11 3. If the push-button 46e is depressed to a greater extent than necessary, t le contact portion 11 3a is deflected while in contact with the side electrode portions 244 and comes into abutment with the circuitry supporting pedastal 1 50 to limit the stroke of the push-button 46e.

The other push-buttons 46a, 46b, 46c, 46d have the same structure as described above. Thus, the foregoing switch portion of the present embodiment is composed of the push-button 46e, the spring portion 11 3 and contact port on 11 3a of the circuitry supporting plate 2CO, and the side electrode portion 244 of the circuit board 200. This is an extremely si nple structure which provides a highly reliable switch.

The base Dlate 100 is the principal constitutent of the t,mepiece movement and, in being connected t(i the anode side serves as a member for supplying powe to the IC 203 and as a cor tact for the switch portions. It also serves s a spring for restoring the pushbutton 46e. This is intended to reduce the number of parts and to simplify the structure, thereby making possible a smaller and thinner timepiece module. There is no need to provide a coil spring for restoring the push-button 46e. This has structural advantages with regard to the timepiece case and contributes to a thinner timepiece.

The next item installed is an insulating dial spacer 340 comprising a synthetic resin, The dial spacer 340 has approxinately the same shape as the opening 420 of the liquid crystal display device 60 and is so forked as to give access to the heads of the screws 276, 278, 280, the winding frame 16lid of the drive coil 164, and the terminal porticns of the conductor 164e. The dial spacer 3L-0 is positioned by the center pipe 1 401.

The dial 44a is installed next. Braized onto the dial 44a are the legs 44a', 44a" consisting of a soft metal such as copper. The legs 44a', 44a" are passed through the holes 2014, 2015 in the circuit board 2000 and are inssrted into the holes 1235, 1 236 provided in the circuitry supporting pedestal 1200. Next, the dial fastening shafts 1201, 1 202 In the shape of eccentric shafts are turned to allow portions of the shafts to bite into the end portions of the legs 142a, 1 42b to secure them. This causes the legs 142a, 1 42b 10 bend slightly and contact the circuitry supporting plate 100. The dial 1 42 has approximately the same shape as the opening 420.In mounting the dial, positioning is accomplished by the end portion of the center pipe 156a to avoid a lack of concentricity between the dial 44a and the center wheel pinion 1 74b and hour hand shaft 178b. The legs 44a1, 44a" of the dial 44a are disposed in the opening 420. The hours hand 44b and the minute hand 44c are attached to the ends of the hour hand shaft 1 78b and center wheel pinion 174b, respectively, in the usual manner.

The timepiece movement is now placed in the case band 52. In the structure adopted, the timepiece movement and case band 52 are fit together by eight projections 150x which are provided on the outer periphery of the main plate 150, and which engage with the inner wall 52a of the case band 52.

Adopting this structure prevents the timepiece movement from being moved within the case band 52 when the push-buttons 46a through 46e are depressed, thus avoiding a difficulty in which the switches cannot be operated owing to insufficient push-button stroke. The fitting state between the case band 52 and the projection 150x on the main plate 1 50 is shown in Fig. 12.

Numeral 282 denotes a bacl < cover which forms a portion of the timepiece case. A vibrating plate 286 constituting the soundgenerating device is attached to the back cover 282 and forms a unitary body with.a semi-circular piezoelectric element 288 that is bonded thereto. Electrode films are formed on both surfaces of the piezoelectric element 288 by an evaporation technique or the like. The output signal from the sound-generating circuit 28 is applied to the piezoelectric element 288 through the connector spring 134, the vibrating plate being caused to vibrate and produce an audible tone. The tone is increased in volume by a cavity formed between the back cover 282 and device cover 330, and is emitted from sound emitting holes provided in the back cover 282.

The case band 52 and back cover 282 are joined together as shown in Fig. 10, where a flat spring 52c provided on the band mounting portion of the case band 52 is engaged with a groove 282b.provided in the back cover 282. Numeral 284 denotes a waterproof packing which is placed upon the step portion 3301 of the device cover 330 and the step portion 52b provided on the case band 52, the packing holding the vibrating plate 286 tightly in place.

The foregoing step completes the assemblage operation. The following description will deal with the impact-resistant structure including the measures for preventing breakage the liquid crystal display device 60.

The component of the largest mass in the timepiece module is the battery 144, and it is this component that is primarily responsible for the impact force that arises when the timepiece receives an impact. Accordingly, it is of critical importance to adopt a structure which does not allow the impact force attributable to the battery to act upon readily breakable components such as the liquid crystal display device. This is especially true in the case of the liquid crystal display device 60 which, in accordance with the present embodirnent, has only one-half to one-third thestrength of conventional liquid crystal display devices owing to the opening formed in the central portion thereof.

If the timepiece receives an impact directed from the back cover 282, the battery 144 receives the, impact from the same direction and generates an impact force owing to-its mass. Although a portion of the impact force acts upon the battery receiving spring 70 and is absorbed by the contact spring portion 70b, the majority of the impact force acts upon the main plate 150 and upon the circuit board 200 disposed beneath the main plate 150.

The circuit board 200 would be deformed at such time and would abut against the reflector 419, the latter striking the liquid crystal display cell 60 and causing it to break. The structure adopted in the present invention is based on recognition of these facts and allows the impact force exerted by the battery 144 to escape from the main plate 150 into the case band 52 through the circuit board 200 and liquid crystal cell holding frame 320. To be more specific, the outer peripheral portion of the circuit board 200 is provided with the six projecting portions 232 through 242. Three of these projecting portions 232, 234, 236 are provided close together at that location of the timepiece where the battery 144 is installed.These three projecting portions 232 through 236, one of which 234 is shown in Fig. 12, are in close contact with the main plate 1 50 and the cell holding frame 320.

Consequently, the impact force exerted by the battery 1 44 upon the supporting pedestal 1 20 is transmitted from the main plate to the circuit board 200 and thence to the cell holding frame 320, from whose shoulder portion 321 4 the force escapes into the case band 52. Furthermore, the gap between the circuit board 200 and reflector is made as large as possible to prevent the reflector 419 from being thrust upwardly owing to deformation of the circuit board 200. In addition, the cell holding frame 320 has the picture frame shape described above to support the liquid crystal display device 60 along the entire outer peripheral portion thereof to prevent any imbalance in the holding force.

The impact resistance structure described above makes it possible to practically employ the annular liquid crystal display cell 60 despite the fact that it has only one-half to onethird tie strength of the conventional liquid crystal display cells.

Measures for dealing with static electricity will be described next.

In ganeral, electronic timepieces are prone to the influence of static electricity which can lead to such problems as disturbance of display a 1d a decline in time-keeping accuracy.

Static electricity can occur when putting on or taking off clothing or when two pieces of synthetic resin are rubbed together, and there are relatively many opportunities for an electronic timepiece to experience static electricity produced in this manner.

Accordingly, the electronic timepiece according to the present invention is so adapted that the timepiece module is shielded against static electricity by the circuitry supporting plate 100, dial 44a and case band 52, with the principal movement constituents that are made of synthetic resin being grounded to the anode side. This affords an effective structure for dealing with static electricity. More specifically, the synthetic resin constituents of the movement are the main plate 150, cell holding frame 320, device cover 330, circuit board 200 and dial spacer 340. The main plate 150 is in intimate contact with the base plate 100 that is grounded to the anode side and hence, it too is grounded through the supporting plate and therefore protected even if electrified by static electricity.The cell holding frame 320 is in contact not only with the main plate 150 at the hook portions 3202 through 3207, but also with the case band 52 at the shoulder portion 3214. Therefore the cell holding frame 320 is grounded by virtue of the fact that the case band 52 is grounded to the anode side. Similarly, the device cover 330 is grounded to the base plate 100, and the circuit board 200 is grounded to the base plate 100 by the conductive patterns 2029 on the anode side. The dial spacer 340 is in contact with the dial 44a, and is therefore grounded to the base plate 100 through the dial legs 44a', 44a".

Thus, the above structure provides an electric timepiece having an extremely high tolerance to static electricity.

This completes the detailed description of the electronic timepiece according to the invention. The characterizing features of the invention may be summarized as follows (1) The analog display portion is disposed in a plane at the center of the timepiece, and the digital display portion is arranged around the outer periphery of the analog display portion, with both display portions being dis posed at approximately the same level when viewed in section. This enhances the harmony between the analog and digital display por tions and makes it easier to read the displays.

(2) The analog display means employs two hands to indicate the hour and minute, and the annular liquid crystal display device indi cates seconds by means of the annular array of segments. This heightens the sense of unity, harmony and correlation between the analog and digital display portions.

(3) The annular array of segments pro vides a unique display such as the revolving scan display in the stop-watch mode, thereby raising the commercial value of the timepiece.

(4) A hand-setting mechanism is unneces sary owing to the adoption of the electronic correction system. This permits the analog display mechanism to be simplified and ar ranged in block form.

(5) A slip mechanism for the center wheel is unnecessary owing to the adoption of the electronic correction mechanism, thereby sim plifying the assemblage and adjustment oper ations.

(6) A supporting structure is adopted wherein the entire outer periphery of the liq uid crystal display cell is supported by the cell holding frame having the picture frame confi guration. This uniformalizes the holding force and is an effective measure for preventing breakage of the liquid crystal display cell.

(7) The supporting structure for supporting the entire outer periphery of the liquid crystal display cell by the picture frame-shaped cell holding frame reduces the width from the panel cover to the outermost edge of the movement, thereby providing a finely rimmed structure which enhances timepiece design.

(8) The liquid crystal cell holding frame has a coupling structure that relies upon hooks, thereby enabling a reduction in the number of parts while enhancing the assem blage operation.

(9) The outer peripheral portion of the circuit board is provided with projections that transmit the impact load attributed to the battery to the case band through the cell holding frame, thereby enhancing the impact resistance of the timepiece.

(10) The circuitry supporting plate serves - as the principal foundation for the timepiece module, improving the rigidity of the module.

(11) In addition to serving as the principal foundation for the module, the circuitry sup porting plate also serves as a portion for supplying power from the power supply, a static electricity shield, contacts for the switch portions and a spring for restoring the push buttons. The result is a reduction in the num ber of parts and a smaller, thinner module.

(12) The switch spring portions provided on the circuitry supporting plate have end portions which are caused to engage with stopper portions provided on the circuitry supporting plate itself. This improves the assemblage operation.

(13) The principal constituents of the module that are made of synthetic resin are grounded to the anode side to prevent electrification by static electricity.

Thus, the electronic timepiece according to the present invention as described above has numerable characterizing features and an extremely high practical value.

Claims (6)

1. An electronic timepiece comprising: a circuit board mounting electronic components including an integrated circuit to provide first and second signals; analog display means including a stepping motor driven by said first signal; a wheel train for speed reducing and transmitting a mechanical output of said stepping motor; upper and lower wheel train bridges for supporting said wheel train; said analog display means being composed of hands driven by said wheel train, and a dial; and electro-optical display device driven by said second signal from said integrated circuit; said analog display means being disposed in approximately the center of the timepiece; said electro-optical display device being annularly disposed in a plane around a periphery of said analog display means; said circuit board being placed over a region of both said analog display means and said electro-optical display device; and said circuit board being disposed between said dial and said lower wheel train bridge arranged on the side of said dial.

2. An electronic timepiece according to claim 1, in which said stepping motor has a drive coil, and in which said circuit board has an access hole for receiving at least a portion of said drive coil.

3. An electronic timepiece according to claim 1, in which said circuit board is secured to at least one of the upper and lower wheel train bridges.

4. An electronic timepiece according to claim 1, further comprising a sheet-like insulating member disposed between said circuit board and lower wheel train bridge.

5. An electronic timepiece according to claim 1, further comprising an insulating member disposed between said circuit board and said dial, said insulating member serving as a clearance-maintaining member for the clearance between said circuit board and said dial.

6. An electronic timepiece substantially as shown and described with reference to the accompanying drawings.