Tuning device and radio-wave corrected timepiece

• US 7,583,942 B2
• Filed: 05/20/2004
• Issued: 09/01/2009
• Est. Priority Date: 05/20/2003
• Status: Expired due to Fees

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Holdings Co., Ltd. (Citizen Electronics Company Limited)
• Inventors: Ihara, Takashi
• Primary Examiner(s): Nguyen; Duc M
• Application Number:
  US10/549,456
• Publication Number:
  US 20060176777A1
• Time in Patent Office: 1,930 Days
• Field of Search: 455/180.4, 455/185.1, 455/186.1, 455/188.1, 4551911-1913, 4551931-1933, 455/194.2, 455/340, 455/352, 455/151.1, 455/151.2, 455/418, 455/419, 455/420, 368/47, 368/21
• US Class Current: 455/193.1
• CPC Class Codes: G04R 20/10 Tuning or receiving; Circuits therefor
• CPC Class Codes: G04R 60/12 inside metal cases
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H

Abstract

A tuning apparatus is provided, wherein the on and off resistances of semiconductor switches within an tuning IC are optimized, so as to provide high sensitivity and superior stability, a wide range of tuned frequency variation, compactness and high performance. The tuning apparatus has a tuning circuit, which has N-channel MOS transistors (N transistors) 5a through 5f, serving as a plurality of semiconductor switches, and a counter circuit 6, which controls the opening and closing of the N transistors, a plurality of capacitors 4a through 4f, which are each connected in series with the plurality of N transistors, and a receiving antenna 2 wherein the total electrostatic capacitance of the plurality of capacitors is varied by the opening and closing of the plurality of N transistors, thereby varying the frequency tuned by the plurality of capacitors and the receiving antenna.

Claims

1. A radio controlled timepiece comprising following items incorporated into an exterior part:

a tuning circuit comprising a semiconductor substrate which comprises a plurality of semiconductor switches, a plurality of first capacitors, connected each in series with said plurality of semiconductor switches, switch controlling means for controlling opening and closing of said semiconductor switches, and a coil connected in parallel to said plurality of first capacitors;

wherein the total electrostatic capacitance of said plurality of first capacitors is varied according to the electrostatic capacitance corresponding to a standard radio wave that includes time information by said switch controlling means individually controlling said opening and closing of said plurality of semiconductor switches connected to said plurality of first capacitors, so as to vary a tuned frequency of a tuning circuit formed by said plurality of first capacitors and said coil;

a control means, which controls said tuning circuit, and which has a receiving circuit, which inputs a standard radio wave received by said tuning circuit and performs time correction; and

a display means, which displays time information from said control means;

a wireless interface circuit that wirelessly receives a control signal for making said control means execute a control of changing the tuned frequency by opening and closing said semiconductor switches respectively and tuning control information for setting the tuned frequency; and

a tuning control information memory that stores the tuning control information.

2. The radio-controlled timepiece according to claim 1, wherein the exterior part is made of a metal material.

3. The radio-controlled timepiece according to claim 1, comprising a test mode, whereby it is possible to change a tuned frequency by an external operating means provided outside said radio-controlled timepiece,

wherein the wireless interface circuit receives the control signal and the tuning control information in the test mode.

4. The radio-controlled timepiece according to claim 1, wherein said tuning control information memory is provided within said tuning circuit.

5. The radio-controlled timepiece according to claim 1, wherein, by controlling the opening and closing of said plurality of semiconductor switches of said tuning circuit so as to vary said tuned frequency, it is possible to selectively receive any of a plurality of standard radio waves.

6. The radio-controlled timepiece according to claim 1, further comprising, either on said semiconductor substrate or outside said semiconductor substrate, a second capacitor, which has either a fixed capacitance or a variable capacitance, and which is connected to said coil in parallel with said group of first capacitors.

7. The radio-controlled timepiece according to claim 6, wherein at least one of said second capacitances is controlled by said switch controlling means via said semiconductor switch provided on said semiconductor substrate.

8. The radio-controlled timepiece according to claim 6, wherein said electrostatic capacitance of said second capacitor is larger than that of said first capacitor.