Casio Computer Co Ltd developed the "Tough Movement," a movement for radio controlled solar watches that features a high shock resistance and a hand position correction function using LED.
The Tough Movement can receive time calibration signals from six bases located in Kyushu area and Fukuoka in Japan, the US, the UK, Germany and China.
The new movement combines metal and plastic parts in order to reduce the weight, while increasing the rigidity. It is designed in consideration of the shape and the position of each part, and the balance between the volume of metal and plastic parts.
In addition, Casio used two metal positioning pins provided on the plate supporting the movement and the dial plate, and increased the diameter of the shaft. As a result, the durability against bending as well as against damage and displacement by shock is improved.
The positions of the hands are detected at 55'00" of every hour and if the time indicated by the watch does not coincide with that of the time counter in the IC, the movement corrects the hand position.
The movement has a structure where the gears for second, minute and hour are sandwiched between the LED and the phototransistor. With this setup, it is possible to detect the positions of three gears by one sensor. The LED emits light 16 times a second to check the positions of the 300mum diameter detection holes that are formed on the gears.
In order to provide this function, Casio developed the CA07 production line, which is dedicated to Tough Movement. The line determines the direction of gears and accurately assembles the gears with reference to the hand position detection holes with a diameter of 300mum, according to the company.
With the adoption of the "Quartzless Heterodyne Method," which eliminates the need for a quartz filter for signal reception, the company reduced the number of parts while maintaining the reception sensitivity. Furthermore, size reduction of the reception LSI resulted in a thinner profile.
With the use of the new movement, the thickness of the three-hand analog model is reduced by 2.26mm to 4.11mm, while that of the chronograph model is reduced by 0.55mm to 4.9mm.
Casio plans to use Tough Movement for its Oceanus and G-Shock series. As the first stage, the company will combine the G-Shock "Giez" and Tough Movement and release it under the model name "GS-1200" on Sept 30, 2008. The GS-1200 will be available at ¥42,000 (including tax, approx US$388) in Japan.