Nihon Dempa Kogyo Co., Ltd.

Chisato Ishimaru

Shigeyoshi Murase

Toshikatsu Makuta

Wen Jen Chen

A dual-mode crystal oscillator includes a single AT-cut quartz crystal piece, a package, and an integrated circuit. The integrated circuit includes an oscillation circuit configured to cause the AT-cut quartz crystal piece to oscillate at a frequency in the MHz band, a dividing circuit configured to divide the frequency in the MHz band to generate a frequency of 32.768 kHz, a selection circuit configured to select one of a pause state where the frequency in the MHz band is not output and an active state where the frequency in the MHz band is output. The mounting surface includes three electrodes arranged in a direction along the long side and two electrodes arranged in a direction along the short side. The electrode to output the frequency of 32.768 kHz and the electrode to output the frequency in the MHz band are arranged not adjacent to one another.

Dual-mode crystal oscillator

A crystal device has an area defined inside a ceramic case thereof, and this area is made larger to increase the design freedom for mounting of a crystal unit (crystal element) in the crystal device. The crystal device is configured such that at least one crystal element is housed in a ceramic case in a rectangular form as seen in plan view. The crystal device includes the ceramic case having a bottom wall and a frame wall, and whose cross section is formed to be concave, and a metal cover jointed to a metal ring provided at an end face of the opening of the ceramic case by seam welding, to hermetically encapsulate the crystal element therein. The crystal device is configures such that one of the widths of the long side and the short side of the metal ring is shorter than the other one.

Crystal device for surface mounting

A surface-mounted device includes a ceramic case, which has a concave portion formed by a bottom wall layer, a frame wall intermediate layer and a frame wall upper layer, and which houses at least a crystal element inside the concave portion. The ceramic case includes: arc-formed notched parts at outer circumference four corners thereof; and mounting terminals, which are extended to notched parts in the bottom wall layer among the notched parts, on an outer bottom face thereof. A radius of curvature of the notched parts in the frame wall intermediate layer is made identical to or greater than a radius of curvature of the notched parts in the bottom wall layer, and a radius of curvature of the notched parts in the frame wall upper layer is less than the radii of curvature of the notched parts in the bottom wall layer and the frame wall intermediate layer.

A crystal device for surface mounting, in which a metal cover is jointed to the metal ring by seam welding, satisfies relationships A/A&#x3c;C/Cand B/B&#x3c;D/Dwhere Ais a length of a long side of the metal ring, Ais a length of a straight portion of a long side except for curved portions, Bis a length of a short side of the metal ring, Bis a length of a straight portion of the short side except for the curved portions thereof, Cis a length of a long side of the metal cover, Cis a length of a straight portion of the long side except for the curved portions thereof, Dis a length of a short side of the metal cover, and Dis a length of a straight portion of the short side except for the curved portions thereof.

A crystal oscillator includes an oscillator circuit, a main body, a first switching circuit, a second switching circuit, and a voltage detecting circuit. The oscillator circuit includes an IC chip including an output circuit and a function circuit. The crystal element includes a first excitation electrode and a second excitation electrode. The main body houses the oscillator circuit and the crystal element and includes a power supply terminal, a ground terminal, an output terminal, and a function terminal. The output terminal is electrically connected to the output circuit and the first excitation electrode via the first switching circuit. The function terminal is electrically connected to the function circuit and the second excitation electrode via the second switching circuit. The first switching circuit and the second switching circuit are operated on the basis of a switching signal from the voltage detecting circuit connected to the power supply terminal.

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Saitama, Japan

Chisato Ishimaru