JPH10197663A - Electronic analog clock using multistage reduction wheel train - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of a reduction wheel train by reducing the rotor equivalent inertia of the wheel train by constituting the wheel train in multiple stages. SOLUTION: In a reduction wheel train, a rotor pinion 1a, a sixth wheel pinion 2a, and a fifth wheel pinion 3a are respectively meshed with a sixth wheel gear 2b, a fifth wheel gear 3b, and a fourth wheel gear 4b. The rotor equivalent inertia of wheel train is considered for the section from a rotor 1 to a fourth wheel 4. Since the rotating speeds of wheel gears become faster as going toward the rotor 1, the influences of the wheel gears on the rotor equivalent inertia become larger as going toward the rotor 1. Therefore, when the inertias of the wheel gears nearer to the rotor 1 are reduced, the inertia of the whole wheel train can be reduced. It is effective to reduce the radii of the wheel gears as much as possible, because the radii act on the inertia four-power times as much as its value. Therefore, the size of the sixth wheel gear 2b which is engaged with the rotor pinion 1a is reduced and, at the same time, a fifth wheel 3 is interposed between the sixth wheel gear 2b and the fourth wheel 4 so that the reduction ratio from the rotor to the fourth wheel 4 can become the same as that of the conventional example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic analog timepiece having a characteristic reduction gear train.

[0002]

2. Description of the Related Art In a conventional wheel train of an electronic analog timepiece, as shown in FIG.
a meshes with the fifth gear 3b, and the fifth wheel pinion 3a meshes with the fourth gear 4b. There are several combinations of the reduction ratio of the rotor 1 and the fifth wheel 3 and the reduction ratio of the fifth wheel 3 and the fourth wheel 4. 1/30 deceleration, which is converted into the second step angle of 6 degrees, is performed. Although the third wheel and the minute hand actually exist after the second hand, they are not specifically mentioned here.

As described above, the stepping motor drives the wheel train and the hands to rotate. It has been found that in order to drive the step motor with less power consumption, it is necessary to reduce the inertia of the gear train. Therefore, conventionally, the inertia of the gear train has been reduced by means such as reducing the size of the gear, hollowing out the gear, or using a plastic material as an engineering plastic.

[0004]

However, there is a limit to the size of the tooth profile that can be processed, and it is difficult to make a gear smaller than a certain size because the reduction ratio must be maintained at 1/30. There was a problem of becoming. Further, even when the gear is hollowed out, only the inner part of the gear is pulled out, so that there is a problem that the effect of reducing the inertia is not so large. For these reasons, there is a limit to reducing power consumption.

[0005] In order to solve such a problem, the present invention employs a mechanism that reduces the number of stages in a reduction gear train, thereby reducing the inertia of the gears and reducing the power consumption. The purpose is to obtain an electronic analog timepiece using a reduction gear train.

[0006]

According to a first aspect of the present invention, there is provided an electronic analog timepiece using a multi-stage reduction wheel train according to the present invention. A step motor driven based on a drive signal output from the drive circuit; and a driving force transmitting unit that transmits a driving force of the step motor to a pointer.
This driving force transmitting means is characterized in that it includes a reduction gear train having three to five gear stages between the step motor and the second hand.

According to a second aspect of the present invention, there is provided an electronic analog timepiece using a multi-stage reduction wheel train, comprising a configuration as set forth in the first aspect, wherein a rotor pinion fixed to the shaft of the step motor and a first gear meshing with the rotor pinion are provided. A speed reduction ratio between the first gear and the second gear engaged with the first gear is smaller than a speed reduction ratio between the first gear and the second gear engaged with the first gear.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. First, a block diagram of an electronic analog timepiece is shown in FIG. The pulse signal output by the oscillation circuit 10 composed of a crystal oscillator or the like is frequency-divided by the clock / drive circuit 11 and converted into a drive signal for driving the step motor 12. The rotational driving force generated by the step motor 12 is the driving force transmitting means 1 including the speed reduction train.
The rotation is transmitted to the hands such as the hour, minute and second hands by 3 to cause the hands to rotate.

FIG. 1 is a view showing an embodiment of the present invention, and shows a configuration of a reduction gear train of an electronic analog timepiece. FIG.
, The rotor pinion 1a meshes with the sixth gear 2b, the sixth pinion 2a meshes with the fifth gear 3b, and the fifth pinion 3a meshes with the fourth gear 4b. With the step rotation of the rotor 1 by 180 degrees, the second hand 5 engaged with the fourth wheel 4 rotates 6 degrees.

[0010] In the wheel train, each gear has inertia with respect to its own rotation axis. However, when the gears mesh and interlock, the rotational speed differs depending on the gear if the number of teeth is different. Therefore, the load on the wheel train connected to the rotor is not a simple sum of the inertia of the gears of the wheel train, but a rotational speed ratio, that is, a reduction ratio. Is the sum of the inertia affected by

Here, a rotor obtained by adding inertia of a gear in consideration of a rotational speed ratio of each gear to a rotor is referred to as rotor equivalent inertia. Here, the rotor equivalent inertia is considered for the range from the rotor to the fourth wheel.
Originally, the rotor equivalent inertia should be considered for all gears and needles to which the rotor transmits rotation.However, considering the reduction ratio that increases as the distance from the rotor increases, the effect of the rotating body after the second hand is very small. Ignore it. The rotor equivalent inertia is It, the rotor inertia is Ir, the sixth wheel inertia is I ₆ , the fifth wheel inertia is I ₅ , the fourth wheel inertia is I ₄ , the second hand 5 inertia is Is, and the sixth wheel for the rotor is sixth. Assuming that the rotation speed ratio of the vehicle is p, the rotation speed ratio of the fifth wheel to the rotor is q, and the rotation speed ratio of the fourth wheel to the rotor is r, the rotor equivalent inertia It is expressed by the following equation. It = Ir + p ² × I
₆ + q ² × I ₅ + r ² × (I ₄ + Is) (1).

In a reduction gear train, since the gear speed is higher as the stage is closer to the rotor, the gear closer to the rotor has a greater effect on the rotor equivalent inertia as can be seen from equation (1). Therefore, reducing the inertia of the gear close to the rotor reduces the overall inertia. Since the radius of the gear is effective to the fourth power with respect to the inertia, the radius may be reduced as much as possible. Therefore, the size of the sixth wheel 2b meshing with the rotor pinion 1a is reduced, and at the same time, the fifth wheel & pinion 3 is provided between them so that the reduction ratio up to the fourth wheel 4 becomes the same as the conventional one.

FIG. 5 shows the specifications of the rotor 1, fifth wheel 3, fourth wheel 4, second hand 5 and the value of the rotor equivalent inertia in the conventional wheel train structure. Here, the fifth wheel 3 for the rotor 1
Of the fourth wheel 4 with respect to the fifth wheel 3 is 1/5.

FIG. 2 shows the specifications of the rotor 1, the sixth wheel 2, the fifth wheel 3, the fourth wheel 4, and the second hand 5 and the value of the rotor equivalent inertia in the wheel train structure according to the present invention. Here, the reduction ratio of the sixth wheel & pinion 2 to the rotor 1 is 1/2, and the sixth wheel & pinion 2
In this embodiment, the reduction ratio of the fifth wheel 3 to the fourth wheel 4 is 1/3, and the reduction ratio of the fifth wheel 3 to the fourth wheel 4 is 1/5. By determining the reduction ratio in this manner, the sixth wheel & pinion 2 can have a smaller gear diameter than the fifth wheel & pinion 3 and the fourth wheel & pinion 4.

The rotor used is the same as the conventional one, and the gears are made of the same material. However, comparing the rotor equivalent inertia, the wheel train structure according to the present invention is about 26 times smaller than the conventional wheel train structure. % Can be reduced. Since the rotor equivalent inertia is a direct measure that quantifies the load, taking into account the inertia of the wheel train and the second hand, reducing the rotor equivalent inertia means reducing the load. The power consumption of the step motor when the same movement is obtained for the hands is reduced.
In the conventional wheel train structure, the power consumption was about 600 nJ, but in the wheel train structure according to the present invention, it was 500 nJ.
To a degree.

In this embodiment, the distance from the rotor 1 to the second hand 5 is 3
Although a configuration using a reduction gear train of stages is shown, it is needless to say that a rotor equivalent inertia can be reduced even if it is configured with four or five stages, and power consumption can be reduced.

In a timepiece gear, the transmission efficiency of one stage is about 0.9. Since the three-stage reduction gear train according to the present invention is one stage more than the conventional two-stage reduction wheel train, the loss is increased by about 10%. If the number of deceleration stages is increased to six, the loss from the viewpoint of transmission efficiency will be greater than the advantage of multi-stages, which will not lead to lower power consumption. Therefore, a reduction gear train of three to five stages is a range that is effective in reducing power consumption.

In the reduction gear train according to the present invention, the center distance between the rotor 1 and the sixth wheel & pinion 2 is shorter than that of the conventional wheel train configuration, and the sixth wheel & pinion 2 is disposed on the wheel train receiver 7 as in the prior art. It can be difficult. In that case, the axis of the sixth wheel & pinion 2 may be arranged on the yoke 6 as shown in FIG.

[0019]

As described above, the rotor equivalent inertia can be reduced and the power consumption can be reduced by configuring the reduction gear train in multiple stages.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a wheel train of the present invention.

FIG. 2 is a table of inertia in a wheel train of the present invention.

FIG. 3 is a plan view illustrating the arrangement of gears in the wheel train of the present invention.

FIG. 4 is a side view showing a configuration of a conventional wheel train.

FIG. 5 is a table of inertia in a conventional wheel train.

FIG. 6 is a block diagram illustrating a configuration of an electronic analog timepiece.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 1a Rotor pinion 2 6th wheel 2a 6th pinion 2b 6th wheel 3a 5th wheel 3a 5th wheel 3b 5th wheel 4 4th wheel 4a 4th wheel 4b 4th wheel 5 second hand 6 Yoke 7 Wheel train receiver 10 Oscillation Circuit 11 Timing / drive circuit 12 Step motor 13 Driving force transmission means 14 Pointer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeaki Shimauchi 840 Takeno, Shimotomi, Tokorozawa-shi, Saitama Citizen Watch Co., Ltd.

Claims (2)

[Claims] 1. A driving circuit that operates based on a clock signal, a step motor that is driven based on a driving signal output from the driving circuit, and a driving force transmitting unit that transmits a driving force of the step motor to a pointer. And a multi-stage reduction gear train characterized in that the driving force transmission means includes a reduction gear train having three to five gear stages between the step motor and the second hand. Electronic analog clock. 2. A reduction ratio between a rotor pinion fixed to the shaft of the stepping motor and a first gear meshing with the rotor pinion, wherein a reduction ratio between the first pinion and the first pinion interlocked with the first gear is set. The electronic analog timepiece using a multi-stage reduction wheel train according to claim 1, wherein the reduction ratio is smaller than a reduction ratio between the second gear and the second gear engaged with the second gear.