GB2101369A - Movement structure for electronic timepiece - Google Patents

Abstract

The present invention provides a movement structure for an electronic timepiece whereby the time-piece is provided with both an analog and a digital display section and is miniaturized so as to be suitable for a lady's wristwatch. The movement structure comprises an opto-electric display device (14) at one end, a stepping motor (18) and a battery (16) at the other, a centrally disposed wheel train (12) coupled to the stepping motor (18), an electronic circuit block (22) comprising an integrated circuit chip and a quartz crystal vibrator, and an externally actuatable switch block (20) surrounded on three sides by the display (14), motor (18) and wheel train (12). The configuration of the movement is such that the positions of the components serve to maximise the area available for the digital display section, while at the same time enabling the movement to be made small and thin. <IMAGE>

Description

SPECIFICATION Movement structure for electronic timepiece At the present time, dual-display types of electronic timepieces are in widespread use. Such timepieces are provided with an analog display section provided with time indicating hands, and a wheel train and stepping motor for advancing the hands, and also a digital display section generally comprising a liquid crystal display cell. Such electronic timepieces have proven extremely successful with regard to sales, due to the advantages of convenience in reading time which is provided by the analog time display section and the high degree of precision in reading the hours, minutes and seconds of time, given by the digital display section. In addition, use of a digital display section enables a large number of different functions to be made available in the timepiece, such as a stopwatch function, timer function, alarm, etc.Data relating to these additional functions can be readily displayed on the digital display section.

However up till the present, almost all of such electronic timepieces have been designed for use as electronic wristwatches by men. This has been due to the fact that a lady's wristwatch must be made very small and thin, due to the dictates of fashion. Hitherto, it has not been possible to produce an extremely small, slim timepiece movement for use in a dual-display electronic timepiece designed as a lady's wristwatch, due to the space required for the analog and digital display sections and the components associated with these.However with a timepiece movement configuration for an electronic timepiece with combined analog and digital display sections according to the present invention, it becomes possible to provide a very small and thin movement, whereby an electronic timepiece can be manufactured which is comparable in size to the smallest analog electronic timepieces produced until now, and which is highly suitable for use as a miniature lady's wristwatch.

According to the present invention, there is provided a movement structure for an electronic timepiece providing both analog and digital displays of time information, said movement having an oblong shape with major and minor axes of symmetry and a major and a minor dimension as measured in the direction of said major and minor axes respectively, comprising: an opto-electric display device disposed at one end of said timepiece movement; a stepping motor disposed at the opposite end of said timepiece movement to said electro-optical display device; a battery disposed adjacent to said stepping motor at said opposite end of the timepiece movement; a wheel train coupled to said stepping motor and disposed substantially in a central region of said timepiece movement; an electronic circuit block comprising an integrated circuit chip and a quartz crystal vibrator element, with said quartz crystal vibrator element being positioned between said wheel train block and said opto-electric display device; and an externally actuatable switch block positioned at one side of said timepiece movement such as to be surrounded on three sides thereof by said wheel train block, said optoelectric display device, and said stepping motor.

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Fig. 1 is a plan view of an embodiment of a movement for an electronic timepiece in accordance with the present invention; and Fig. 2 and Fig. 3 are cross-sectional views in elevation through important portions of the embodiment of Fig. 1.

Referring first to Fig. 1, a plan view is shown of an embodiment of a timepiece movement having a configuration in accordance with the present invention, provided with both analog and digital display sections. Fig. 2 and Fig. 2, which are crosssectional view through portions of Fig. 1, will also be referred to. Numeral 10 denotes a liquid crystal display cell support frame, which also forms the timepiece baseplate. This has an oblong shape, with a major axis and minor axis of symmetry: and determines the overall shape of the timepiece movement itself.The major dimension of the timepiece movement (i.e. as measured in the direction of the major axis of symmetry) is designated by the letter A in the drawings, and the minor dimension (i.e. as measured in the direction of the minor axis of symmetry) is designated by the letter B. The timepiece movement may have a rectangular, or barrel-shape, etc.

Numeral 12 denotes a wheel train block for driving the timepiece hands (not shown in the drawings). The wheel train block 12 is positioned close to the center of the timepiece movement, i.e.

near the central portion of liquid crystal display supporting frame 10. A liquid crystal display unit 14 for proving a digital display of time information is disposed at one end of the timepiece movement, as shown in Fig. 1, while a battery 1 6 and stepping motor 1 8 are arranged at the opposite end of the timepiece movement, with the stepping motor 1 8 being positioned close to the wheel train block 12. A switch block 20 is positioned at one side of the timepiece movement, such as to be surrounded on three sides by the liquid crystal display unit 14, the wheel train block 12 and stepping motor 1 8. Numeral 24 denotes a quartz crystal vibrator element and numeral 26 a buzzer voltage step-up coil which are components of an electronic circuit block 22.The quartz crystal vibrator element 24 and buzzer voltage step-up coil 26 are positioned between wheel train block 12 and liquid crystal display unit 14. The wheel train block 12 comprises a set of gear wheels arranged to transmit rotation from stepping motor 18 to the timepiece hands, with the order of transmission being, successively, to a 4th wheel 25, a 3rd wheel 26, a 2nd wheel 27, a minutes wheel 28 and an hours wheel 30. The 2nd wheel 27 and minutes wheel 28 are mounted between a center bridge 32 which is attached to liquid crystal display supporting frame 10 by a wheel train support pillar 34, and a bearing plate 36. The bearing plate 36 is positioned in the vertical direction by abutting against a portion of liquid crystal display supporting frame 10, as shown in Fig. 2.Bearing plate 36 is attached to liquid crystal display supporting frame 10 by a bearing plate screw 38, as shown in Fig. 2.

The 3rd wheel 36 and 4th wheel 25 are mounted between wheel train bridge 40 and bearing plate 36. Wheel train bridge 40 is supported by wheel train support pillar 34, and is attached to liquid crystal display supporting frame 10 by wheel train bridge screws 42 and 44, with screw 42 being screwed into wheel train bridge supporting pillar 34. The liquid crystal display unit 14 comprises a liquid crystal display cell 46, a liquid crystal display cell reflector plate 48, and a connecting rubber member 52. The length of the major dimension of liquid crystal display cell 46 is arranged to be almost identical to that of the minor dimension B of the timepiece movement, and is designated as C in Fig. 1.This relationship between the dimensions of liquid crystal display cell 46 and the timepiece movement enables the size of the digital display section to be maximized, for easier reading of the displayed digits. Liquid crystal display cell 46 is mounted in a recessed portion formed in liquid crystal display supporting frame 1 0. Electrical connections between liquid crystal display cell 46 and electronic circuit block 22 are established by means of connecting rubber member 52, which is compressed between a circuit substrate 72 and liquid crystal display cell 46 as shown in Fig. 2. The connecting rubber member 52 also acts to position the reflector plate 48 which is mounted over the rear face of liquid crystal display cell 46, as illustrated in Fig. 2.A spacer member 84, forming part of electronic circuit block 22, serves to position liquid crystal display cell 46 in the vertical direction.

The shape of the circumference of the timepiece movement adjacent to battery 1 6 is arranged to correspond in shape to the circumference 54 of battery 1 6. In addition, a portion of the circumference of battery 1 6, indicated by numeral 56, is arranged to be positioned close to the outer peripheries of the 2nd wheel 27 and 4th wheel 25. A portion 58 of the hours wheel 30 is arranged to overlap battery 16, in the horizontal plane.

Stepping motor 1 8 comprises a coil block 60, a stator 62, and a rotor 64. Battery 1 6 is positioned with respect to stepping motor 1 8 such that magnetic coupling will not occur between battery 1 6 and coil core 66 or stator 62. The sum of the diameter of battery 1 6 and the length of coil core 66 is arranged to be almost identical to the length of the minor dimension B of the timepiece movement.

Rotor 64 of stepping motor 1 8 is mounted between bearing plate 36 and wheel train bridge 40. Stator 62 is mounted on the upper face of bearing plate 36 (as viewed in Fig. 1 and Fig. 3).

The stepping motor coil block 60 is fixed at one end by a coil block fixing screw 68, to ensure magnetic coupling between coil block 69 and stator 62.

Numeral 20 denotes a switch block, which is externally actuatable for performing time correction operations, etc. Switch block 20 comprises a crown (not shown in the drawings) which is attached to a stem 70. Stem 70 is coupled to a switch which is operable by movement of the stem 70 in the axial direction, and a switch which is operable by rotation about the axis of stem 70, these switches being contained within switch block 20. Signals generated by actuation of these switches are applied such that, when the crown is pulled outward in the axial direction, a correction condition is established in which the time information displayed by the analog and digital display sections can be corrected by rotation of the crown. Such correction means are well known in the art, and therefore will not be described further.

The electronic circuit block 22 comprises a circuit substrate 72, a supporting plate 74 and a potting frame plate 76, together with an integrated circuit (IC) chip 78, a quartz crystal vibrator element 23 and a buzzer voltage step-up coil 24. The position of the IC chip 78 is arranged such that the chip overlaps liquid crystal display cell 46 in the horizontal plane, at one end of the IC chip, and overlaps quartz crystal vibrator element 23 at the other end of IC chip 78, as illustrated in Fig. 2. IC chip 78 is mounted within a cavity formed in circuit substrate 72 and potting frame plate 76, and is sealed therein by epoxy resin 77.

Electrical connections to IC chip 78 are established by wire bonding between the chip and a conductive circuit pattern formed on circuit substrate 72.

The quartz crystal vibrator element 23 is positioned between liquid crystal display unit 14 and wheel train block 12, such as to partially overlap IC chip 78, and is retained in the requisite position by means of a support member 80, forming part of electronic circuit block 22 and made of synthetic resin, and a recessed portion 82 which is provided in liquid crystal display supporting frame 10 as shown in Fig. 2. The terminals of quartz crystal vibrator element 23 are soldered to a conductive circuit pattern formed on circuit substrate 72, to thereby provide electrical connections between quartz crystal vibrator element 23 and electronic circuit block 22.

The thickness of buzzer voltage step-up coil 24 is arranged to be almost identical to that of the overall thickness of the complete timepiece movement. The buzzer voltage step-up coil 24 is positioned between wheel train block 12 and liquid crystal display cell 46, and terminals of buzzer voltage step-up coil 24 are soldered to a conductive circuit pattern formed on the upper face (as viewed in the diagrams) of circuit substrate 72. The electronic circuit block 22 is attached to liquid crystal display supporting frame 10 by hook members 86 and 88 formed on the frame, and by electronic circuit block fixing screws 90 and 92. Fixing screw 92 also serves to provide electrical connection between a conductive circuit pattern formed on stepping motor coil block 60 and a conductive circuit pattern formed on the upper face of circuit substrate 72.Circuit block fixing screw 92 also serves to provide magnetic coupling between coil block 60 and stator 62. As a result, when pulses of current flow through stepping motor coil block 62 in response to output signals from electronic circuit block 22, the magnetic circuit path formed by coil core 66 and stator 62 acts upon stepping motor rotor 64 to rotate the rotor.

From the above, it can be understood that with a timepiece movement configuration in accordance with the present invention, the length of the major dimension of the liquid crystal display cell is arranged to be substantially identical to the minor dimension of timepiece movement, which is of oblong shape as viewed in plan. This fact enables the area available for the digital display section of the timepiece to be made as large as possible, and thereby overcomes a problem which has arisen with prior art electronic timepieces of dual-display type, in which the size of the digital display section is so small that the numerals formed therein are extremely difficult to read. In addition, the sum of the diameter of the battery and the length of the stepping motor coil core is arranged to be substantially identical to the length of the minor dimension of the timepiece movement.This ensures that sufficient space is provided to easily accommodate the electronic circuit block. Furthermore, the position of the battery is arranged to be close to the gear wheels in the wheel train block, in order to thereby increase the space available for the switch block.

Another feature of an electronic timepiece movement in accordance with the present invention is that components having a thickness which is comparable to that of the overall timepiece movement are separated from one another (as viewed in the horizontal plane), while components which can be made relatively thin, such as the quartz crystal vibrator element and the IC chip, are arranged to overlap one another in the horizontal plane. This enables the overall size of the timepiece movement to be minimized, and allows the completed electronic timepiece to be extremely thin, since the available space for components is highly effectively utilized.

An electronic timepiece incorporating a timepiece movement in accordance with the present invention can be made of comparable size to a conventional miniature analog display type of electronic timepiece used as a lady's wristwatch, but is provided with both a hands display section and a digital display section, each of which is clearly legible. Thus, such a dual-display type of lady's wristwatch will have an enhanced market appeal, by comparison with a conventional analog timepiece.

In the above description, the present invention has been shown and described with reference to a specific embodiment. However it should be understood that various modifications to the above embodiment may be envisaged, which fall within the scope claimed for the present invention.

The above description should therefore be interpreted in an illustrative, and not in a limiting sense.

Claims (5)

1. A movement structure for an electronic timepiece providing both analog and digital displays of time information, said movement having an oblong shape with major and minor axes of symmetry and a major and a minor dimension as measured in the direction of said major and minor axes respectively, comprising:: an opto-electric display device disposed at one end of said timepiece movement; a stepping motor disposed at the opposite end of said timepiece movement to said electro-opticai display device; a battery disposed adjacent to said stepping motor at said opposite end of the timepiece movement; a wheel train coupled to said stepping motor and disposed substantially in a central region of said timepiece movement; an electronic circuit block comprising an integrated circuit chip and a quartz crystal vibrator element, with said quartz crystal vibrator element being positioned among said battery, said stepping motor and said opto-electric display device; and an externally actuable switch block positioned at one side of said timepiece movement such as to be surrounded on three sides thereof by said wheel train block, said opto-electric display device, and said stepping motor.

2. A movement structure for an electronic timepiece according to claim 1, in which said opto-electric display device is of oblong shape and has a major dimension which is substantially equal to said minor dimension of said timepiece movement.

3. A movement structure for an electronic timepiece according to claim 1, in which a portion of said integrated circuit chip of said electronic circuit block overlaps said opto-electric display device, and in which an opposite portion of said integrated circuit chip overlaps said quartz crystal vibrator element.

4. A movement structure for an electronic timepiece according to claim 1, and further comprising a buzzer voltage step-up coil forming part of said electronic circuit block and positioned between said wheel train block and said optoelectric display device.

5. A movement structure for an electronic timepiece substantially as hereinbefore described with reference to the accompanying drawings.