GB2226164A

GB2226164A - Gear mechanism for timepieces

Info

Publication number: GB2226164A
Application number: GB8924505A
Authority: GB
Inventors: Fred Schnak; Karsten Siersleben
Original assignee: RUHLA UHREN VEB K
Current assignee: RUHLA UHREN VEB K
Priority date: 1988-11-30
Filing date: 1989-10-31
Publication date: 1990-06-20
Anticipated expiration: 2009-10-31
Also published as: FR2639727B1; DD277540A1; FR2639727A1; GB8924505D0; DE3926772A1; GB2226164B

Description

1 GEAR MECHANISM FOR TIMEPIECES This invention relates to a gear mechanism

with gear state detection means for radio-controlled timepieces, especially for radio-controlled quartz timepieces.

From Patent Specifications DE 35 10 861 and 35 13 961 gear mechanisms for radio-controlled quartz timepieces are know, wherein the hour hand is driven from a first stepping motor via intermediate wheels and by the hour wheel and the second and minute hands are driven from a second stepping motor via an intermediate wheel, a second wheel, a small centre wheel and minute wheel. The gear mechanisms are equipped with gear state indicator devices. In the case of an adjustment or correction to the clock time, both stepping motors are driven with an increased pulse sequence, so that the adjustment to the hands takes place rapidly.

From DE-Gm 87 12 809, a two-motor gear mechanism is also known, especially for a radio-controlled timepiece, in which the hour wheel and the remaining gear mechanism comprising minute and second indicators are separately driven from two separate stepping motors. The hour wheel is equipped with an aperture, behind which a reflector is situated on the timepiece frame. This assembly is 2 ;ituated in the beam path of a light barrier. In the gear mechanism assembly intermediate wheel-second wheelsmall centre wheel, there is also situated a light barrier system, of which the beam path passes through apertures of these wheels and an angle mirror system to a receiver. The emitter and receiver of light beams are situated partly behind holes on the printed circuit board of the electronic timepiece.

From DE-AS 29 10 736, there is also known a timepiece having an analogue and digital display, the pointer mechanism of which is equipped with a synchronising device. A synchronising disc having an opening, which lies in the beam path of a light-emitting diode and a photocell, is associated with an electromechanical display, consisting of minute tube, gear change wheel and drive and hour wheel.

In timepieces of the above-mentioned kind, setting is necessary after a battery change. For this purpose,. the hands must first be brought in rapid forward movement into a known starting position, e.g. at twelve o'clock. In this setting of the pointer mechanism, the photoelectric detector is activated, so that the setting operation can be initiated by an electronic circuit. Accurate time setting is not possible with this device, 1 3 because the detection of the setting of the hour wheel is too inaccurate for time setting to accuracy of one second, especially for quartz timepieces. The gear assemblies require, for the realisation of the gear state detection devices, a nesting of the wheel discs, so that the gear wheel assembly requires excessive overall height, which is counter to the trend to a flat form of construction in electronic timepieces. With this type of timepiece, the setting times extend to up to twenty minutes.

The objective of the present invention is the creation of a gear mechanism with gear state detection for radio-controlled electronic timepieces, especially quartz timepieces, which permits a shortened adjustment operation and also a flat form of construction.

According to the invention there is provided gear mechanism with gear state detection means for radio controlled timepieces; said mechanism comprising a plurality of stepping motors, a gear train associated with each motor for driving indicator wheels of a time displace, correction wheels having slit-shaped openings and reflectors driven in parallel at least with hour and minute indicator wheels, light sources and detectors for detecting the presence of the openings in the correction wheels and an intermediate plate having slit shaped 4 openings disposed in the paths of the light beams from the sources to the detectors for enabling rapid setting of the indicators.

In a preferred construction, the gear mechanism is subdivided into three gear trains with separate stepping motors. In parallel with the hour and minute wheels, correction wheels having slit-shaped openings, with reflectors behind, are journalled. In the beam path light sourcereflector-receiver of the individual gear trains, an intermediate plate having slit-shaped openings is disposed. The second indicator wheel can also be equipped with a slit-shaped opening having a reflector behind it in conjunction with a light source and detector which provides a further beam passing through another opening in the plate.

The device according to this invention makes possible a flat form of construction for the radiocontrolled timepiece. Compared with the known radio timepieces, very short setting time are achieved by the direct drives of the individual gear trains of the subdivided gear mechanism.

The invention will be explained in more detail below 9:

t> by reference to an example of embodiment thereof. The figures in the associated drawing show:

Figure 1 is a sectional view through a clockwork mechanism constructed in accordance with the invention; Figure 2 is a sectional view of one of the correction wheels; and Figure 3 is a plan view of part of the correction wheel.

In a clockwork mechanism, not further referenced, of a radio-controlled timepiece in accordance with the invention, a gear mechanism is divided into three independent gear trains driven by separate stepping motors 13, 14, 15. These receive drive pulses from an electronic control device, consisting of an oscillator circuit, a divider and driver stages. An hour wheel 1, a minute wheel 2 and a second wheel 3 are rotatably journalled coaxially to one another in a mounting plate 20 and are driven by the appropriate gear train of the gear mechanism. The stepping motor 13 is drivingly connected via an intermediate wheel with the second wheel 3, on the shaft of which the second hand 10 is fixed. The second wheel 3 is equipped with a slit-shaped opening 3b, on the base of which a reflector 3a in the form of a plane mirror is fixed. Opposite the opening 3b, there are disposed in a mounting plate 21, a light source 4, 6 e.g. a light-emitting diode, and a receiver 5, for example a photoelectric cell. The second gear train of the gear mechanism comprises the stepping motor 15, an intermediate wheel and the minute wheel 2, which carries the minute hand 22. Into the drive of the intermediate wheel there engages a correction wheel 12, disposed outside the transmission line of the gear train and corresponding to the minute wheel 2, this correction" wheel 12 having an opening 12b and a reflector 12a. In the field of action of the opening 12b, a light source 6 and receiver 7 are likewise mounted in the mounting plate 21. The third gear train consists of the motor 14, an intermediate wheel and the hour wheel 1, which carries the hour hand 23. Into the intermediate wheel drive there engages the correction wheel 11, lying outside the transmission line and corresponding to the hour wheel 1. It is equipped with an opening 11b and a reflector 11a. The light source 8 and receiver 9 of the mounting plate 21 are associated with this assembly. The reflector assemblies of the correction wheels 11,12 and of the second wheel 3 are of like construction. Between the gear mechanism and the mounting plate 21 an intermediate plate 16 is provided. The plate 16 has slit-shaped openings 16a, 16b, 16c which are disposed in the beam paths of the light sources 4, 6, 8 to the receivers 5, 7,9. The basic setting of the gear mechanism corresponds

T 4 7 to that of Figure 1. The clockwork mechanism may furthermore be provided with a date display.

The method of functioning of the device according to this invention is as follows:

When radio-controlled timepieces fail an accurate, rapid setting is necessary after the source of fault-has been removed. For this purpose, ascertaining of a known state of the gear mechanism is first necessary, corresponding to a specific pointer setting, e.g. twelve o'clock. The gear train is moved in rapid forward motion by the stepping motor 14, until the opening 11b of the correction wheel 11 comes aligned with the opening 16a and the beam path of the light source 8 reaches the receiver 9, which supplies a signal to an electronic evaluating circuit not shown. The stepping motor 15 now moves its gear train, until the correction wheel 12 with its opening 12b is aligned with the opening 16c that the light beam of the light source 6 reaches the receiver 7. This position is also transmitted to the evaluator circuit. Finally, the stepping motor 13 drives the second wheel 3 in rapid forward drive into the opposition position to the light source 4, so that the evaluator circuit receives the last item of information for setting the third gear train. The positions of all three gear trains of the gear mechanism thus reached with only one 8 rapid revolution each of hour wheel 1, minute wheel 2 and second wheel 3 preferably correspond to the pointer setting twelve o'clock. From this starting position, the hour, minute and second hands 23, 22, 10 can be set in rapid forward drive by the electronic circuit to the current clock time.

IF 9

Claims

1. Gear mechanism with gear state detection means for radio-controlled timepieces; said mechanism comprising a plurality of stepping motors, a gear train associated with each motor for driving indicator wheels of a time display, correction wheels having slit-shaped openings and reflectors driven in parallel at least with hour and minute indicator wheels, light sources and detectors for detecting the presence of the openings in the correction wheels and an intermediate plate having slit shaped openings disposed in the paths of the light beams from the sources to the detectors for enabling rapid setting of the indicators.

2. Gear mechanism according to claim 1, wherein there is a indicator wheel for seconds which is also equipped with a slit-shaped opening and a reflector and there is a light source and detector and an opening in the intermediate plate associated with the second indicator wheel.

3. Gear mechanism substantially as described herein and with reference to the accompanying drawings.

Published 1990 at The Patent Office, State House, 66 71 High Holborn. London WC1R4TP. Further copies maybe obtainedfrom The Patent Office-