Electronic watch

• US 3,995,177 A
• Filed: 05/09/1974
• Issued: 11/30/1976
• Est. Priority Date: 01/02/1973
• Status: Expired due to Term

• Current Assignee: Fairchild Camera and Instrument Corporation (ON Semiconductor Corporation)
• Original Assignee: Fairchild Camera and Instrument Corporation (ON Semiconductor Corporation)
• Inventors: Sirocka, Richard L., Broxterman, David F.
• Primary Examiner(s): Zazworsky, John
• Application Number:
  US05/468,782
• Time in Patent Office: 936 Days
• Field of Search: 307/296, 307/297, 307/264, 323/4, 323/22 T
• US Class Current: 326/81
• CPC Class Codes: G04G 19/02 Conversion or regulation of current or voltage
• CPC Class Codes: G04G 9/12 using light valves, e.g. liquid crystals
• CPC Class Codes: G05F 3/24 wherein the transistors are of the field-effect type only G05F3/205, G05F3/26, G05F3/30 take precedence

Abstract

A regulated voltage converter for converting a relatively low voltage to a relatively high voltage. The converter includes a voltage converter for converting a relatively low voltage to a relatively high voltage, a constant current source, reference means coupled to the constant current source and the voltage converter for providing a reference voltage related to the relatively high voltage, a threshold detector coupled to the reference means for generating a control signal when the output of the voltage converter drops below a predetermined threshold value, a sense and enable means responsive to the appearance of the control signal for enablng the voltage converter, and sample means coupled to the constant current source, the threshold detector and the sense and enable means for periodically enabling the operation of these elements. The duration of the enabling period is small relative to the period therebetween.

Claims

1. A regulated voltage converter for converting a relatively low voltage to a relatively high voltage comprising:

a voltage converter for converting said relatively low voltage to said relatively high voltage;

a constant current source;

reference means coupled to said constant current source and said voltage converter for providing a reference voltage related to said relatively high voltage;

a threshold detector coupled to said reference means for generating a control signal when the output of said voltage converter drops below a predetermined threshold value;

a sense and enable means responsive to the appearance of said control signal for enalbing said voltage converter; and

sample means coupled to said constant current source, said threshold detector and said sense and enable means for periodically enabling the operation thereof, the duration of such enabling period being small relative to the period therebetween.

2. The apparatus of claim 1, wherein said reference means comprises an electrical resistance device.

3. The apparatus of claim 1 wherein said threshold detector comprises a source follower transistor circuit having an input coupled to said reference means and an output, and a sensing transistor circuit having an input coupled to said source follower output and an output coupled to the input of said sense and enable means.

4. The apparatus of claim 1, wherein said sense and enable means comprises a flip-flop having a clock input coupled to said sample means and a data input coupled to the output of said threshold detector, a gate coupled to said flip-flop and enabled thereby when said flip-flop is placed in a predetermined one of two stable states by the appearance of a clock signal at said clock input and said control signal at said data input, and a source of drive signals coupled to said gate for passage therethrough when said gate is enabled to drive said voltage converter.

5. The apparatus of claim 1, wherein said sample means comprises a source of sample pulses having a small duration relative to the period therebetween, said source being coupled to said sense and enable circuit, and switching means having a control input coupled to said source for actuation thereby and an input terminal coupled to said constant current source and said threshold detector for enabling these last named elements in response to the generation of said sample pulses.

6. The apparatus of claim 5, wherein the duration of each of said sample pulses is approximately one millisecond and the period therebetween is approximately 250 milliseconds.