Journal of the Horological Institute of Japan

[title in Japanese]

Article type: Cover
1992 Volume 142 Pages Cover1-
Published: September 25, 1992
Released on J-STAGE: November 09, 2017

DOIhttps://doi.org/10.20805/tokeieafj.142.0_Cover1

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[title in Japanese]

Article type: Cover
1992 Volume 142 Pages Cover2-
Published: September 25, 1992
Released on J-STAGE: November 09, 2017

DOIhttps://doi.org/10.20805/tokeieafj.142.0_Cover2

JOURNAL FREE ACCESS

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Time Data Transmission Using Telephone Line

Nakonobu MORITANI, Tadashi AKATSUKA, Tokuo SATO, Masanori AIDA

Article type: Article
1992 Volume 142 Pages 1-16
Published: September 25, 1992
Released on J-STAGE: November 09, 2017

DOIhttps://doi.org/10.20805/tokeieafj.142.0_1

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A time data transmission system has been developed to transfer accurate standard time, by using public telephone line. This system consists of a time data transmission unit and a time data receiver unit, which are mutually connected with the telephone line via MODEM. We have developed the following methods for the delay time compensation in the telephone line. (1) The transmission unit sends the standard time data, and the end of this transmission data is synchronized with the standard second signal, and (2) The time data receiver measures the delay time in telephone line by using MODEM's loop back technology, and the local clock time is corrected to the standard time data. The experimental test on an actual line has comfirmed as a field data that its accuracy of time adjustment is kept within i 200 μs. Furthermore, this system can be fully automated including synchronizing process and be able to send the time data to general purpose terminal such as personal computer.

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Development o f Diver's Watch with an Analog Depth Meter

Noritoshi SUZUKI, Kenzi MIYASAKA, Shinichi YAMADA, Masao SAKUYAMA, Mas ...

Article type: Article
1992 Volume 142 Pages 17-25
Published: September 25, 1992
Released on J-STAGE: November 09, 2017

DOIhttps://doi.org/10.20805/tokeieafj.142.0_17

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Our newly developed electronic diver's watch with an analog depth meter (Cal.5810) displays the depth of water not by liquid crystal as previously done, but indicates the time, the present depth, and the maximum depth which are essential for diving, all by hands. This diver's watch is characterized by a high degree of visibility of the functional depth indicator hands, and the present and maximum depths can be easily read at angles of these hands in usual familiar time sense. The orange-colored depth indicator hands are located in the center of the dial, together with the mainly green-colored hour, minute, and second hands, and unit, one minute corresponds to one meter in depth. This watch can provide divers the dive time and the dive depth means of the angles and color of the hands in a new manner.

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Free Vibration of the Mass-Spring System having Solid Friction Force Proportional to Displacement

Akio ISHIZAKA, Keito TANAKA

Article type: Article
1992 Volume 142 Pages 26-38
Published: September 25, 1992
Released on J-STAGE: November 09, 2017

DOIhttps://doi.org/10.20805/tokeieafj.142.0_26

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For the damping of a mass-spring(m-k) system, a method using a solid friction is comparatively simple and has no problems of oil leakage and no characteristical change by temperature being different from an oil damper. However, the system with such damping has the characteristic of infinite resonance when input exceeds a critical value, and has an offset from the natural equilibrium position. A method to remove these shortcomings utilizing the friction force proportional to the displacement of the mass m was reported elsewhere, in which only the stationary vibration, i.e. the frequency characteristic was discussed. In the present paper, characteristics of the free vibration are theoretically studied, and the results are ascertained by the experiment. Conclusions obtained are summerized as follows: (1) Free vibration can be described by three parameters, α, ρ, and λ, αwhere a is the inclination of the groove, ρ the friction angle between the groove and the solid piece, λ the ratio of k_d to k.k is the spring constant of the m-k system, and k_d is that for another spring which pushes the solid piece to the mass m. (2) Value of the damping natural frequency ω_0 is given by 2ω_1ω_2/(ω_1+ω_2), where ω_1=ω_n〓{1+λtanαtan(α-ρ)}, ω_2=ω_n〓{1+λtanαtan(α+ρ)}, and ω_n=〓(k/m). (3) Damping characteristic of the amplitude is expressed by the logarithmic decrement, 2(ω_1/ω_2), or by the damping ratio, 1/〓|{2π/1n(ω_1/ω_2)}^2}2+1|. (3) Free vibration exists in a domain λ<{tanαtan(ρ-α)}^(-1) on the α-λ plane.

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[title in Japanese]

[in Japanese]

Article type: Article
1992 Volume 142 Pages 39-42
Published: September 25, 1992
Released on J-STAGE: November 09, 2017

DOIhttps://doi.org/10.20805/tokeieafj.142.0_39

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