Manual Citizen Miyota 821A (page 5 of 6) (English, German, French, Italian, Portuguese, Spanish)

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(6)Supplementary explanation

(6)Supplementary explanation (6)Supplementary explanation

(6)Supplementary explanation

①Term explanation for watch test

Beginning operation on the condition of giving utmost power.

Time of gain or delay in some unit and usually converting this time to 24 hours.

The time of gain or delay after 24 hours past from start.

Difference between daily rate of one posture of the watch and another posture.

Time from start to stop.

As time processes, enery inside the watch (mainspring) emits and oscillation

falls which changes time.

②Automatic winding structure (Explanation of mainspring half winding method)

②Automatic winding structure (Explanation of mainspring half winding method)②Automatic winding structure (Explanation of mainspring half winding method)

②Automatic winding structure (Explanation of mainspring half winding method)

For movement of a human arm, we know that there is more slight movement

than strong movement. We can think of the mechanism of winding by the slight

movement from the explanation below.

By moving the watch as Fig－６, rotating oscillating weight rotates as the

arrow direction shown on the picture. In this time, for the case of both

winding method, the amount of rotation becomes less since the oscillating

weight have to overcome the mainspring. On the other hand, when the

oscillating weight on half side winding method rotates idle, there is no brake

like the above mainspring so it rotates very well. Of course, it is idle rotation

so it does not have the winding performance. However the rundown process

by the empty weight wounds the mainspring. Especially the beginning of rundown,

there is an angle where mainspring torque does not work on the oscillating weight.

So it gives more energy for the rotation of oscillating weight that gives more

convenience for winding.

This is why half side winding method

○Wounds well in slight movement

○The strengths of the human arm ranges as Fig－７ and shows

that slight movement creates much more rotation.

From these two facts, we know that we can wind better by half

side winding method.

③Accuracy of mechanical (hand winding ・automatic winding) watch

Mechanical watch operates by elaborate combination of delicate parts (gear,mainspring) and

maintains accuracy. This is why time accuracy changes everyday.

Temperature differece, change in magnetism, the difference in the

living environment of the watch user, all affects accuracy. Also, not much as analogue quartz

but in strong magnetic circle, gains, delay, or stop might occur.

Also, oscillation changes by casing from the movement condition. (Holding the hour

wheel by dial washer, the join of the weight of the hand, and movement itself warps a bit.

Especially it becomes larger by using the screw for case clamp.) This is why there can be a

accuracy equation. After casing, if conducting a fitting in modification for accuracy,

maintaining accuracy in certain level is possible. However, effect of posture difference,

isochronism, temperature, etc is 100 ～ 1000 times larger than the quartz watch.

④About mainspring (hand winding ・automatic winding)

Generally, hand winding watch continues to move for 2 days by winding the mainspring very

hard. However, to keep the watches accuracy, winding the mainspring regularly at the same time

everyday is recommended. Please stop winding the mainspring when power is felt on the

finger of which you have winded the mainspring.

The structure of a automatic winding watch is that the movement of the arm moves the rotar

inside the watch and this power automatically winds the mainspring. The watch will continue

to move for around 2 days if you put on the arm for 8 hours or more in daily life. However,

there will be a slight difference depending on the persons living environment. If putting on a

watch when just commuting to office or on a holiday when taking the watch off and leaving

it out somewhere for a quite a long time, the delay or stop might occur. But in most cases,

it is not broken. Please wind the mainspring and lookout for awhile.

Fig－７

７

Rotation

occurence

Strength of

movement

Fig－６

６

Idle rotation

82xx

82xx82xx

82xx

Endurance time

Isochronism

Daily rate

Start

Accuracy

Posture error

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Citizen Miyota 821A Manual

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