Amplitude measurement device for viscoelasticity analysis

• US 4,984,469 A
• Filed: 11/16/1989
• Issued: 01/15/1991
• Est. Priority Date: 11/21/1988
• Status: Expired due to Term

• Current Assignee: SII Nano Technology Inc. (Hitachi, Ltd.)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Nakamura, Nobutaka, Take, Masafumi, Takeda, Haruo
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US07/437,224
• Time in Patent Office: 425 Days
• Field of Search: 324/130, 324/131, 73/763, 73/765, 73/769, 73/770, 73/789, 73/790, 73/794-797, 73/806, 73/808
• US Class Current: 73/770
• CPC Class Codes: G01N 2203/0005 Repeated or cyclic
• CPC Class Codes: G01N 2203/0071 Creep
• CPC Class Codes: G01N 2203/0094 Visco-elasticity
• CPC Class Codes: G01N 2203/021 Treatment of the signal; Calibration
• CPC Class Codes: G01N 2203/0682 Spatial dimension, e.g. length, area, angle
• CPC Class Codes: G01N 2203/0688 Time or frequency
• CPC Class Codes: G01N 3/32 by applying repeated or pulsating forces

Abstract

An apparatus for providing an indication of the amplitude of a length signal having a top peak, a bottom peak and an intrinsic offset and being indicative of viscoelasticity of a sample. A peak measurement circuit is provided for measuring values of top and bottom peaks of the length signal to determine the amplitude thereof and an offset circuit is connected for providing a compensative offset. An adder circuit is provided for adding the compensative offset to the length signal. An offset calculation circuit receptive of the values of the top and bottom peaks from the peak measurement circuit is provided for outputting to the offset circuit, according to the received values, a control signal effective to control the offset circuit to provide an update compensative offset effective to cancel the intrinsic offset of the length signal.

Claims

1. An apparatus for providing an indication of the amplitude of a length signal having a top peak, a bottom peak and a center value, the length signal being indicative of the viscoelasticity of a sample, comprising:

an offset circuit for providing a compensative offset signal;

an adder circuit connected for receiving the length signal and the compensative offset signal and for producing an output signal having a value representative of the sum of the length signal and the compensative offset signal;

a peak measurement circuit connected to receive the output signal produced by said adder circuit for measuring the values of the top and bottom peaks of the output signal to determine the amplitude of the length signal; and

an offset calculation circuit connected for receiving the values of the output signal top and bottom peaks from said peak measurement circuit and for supplying to said offset circuit a control signal effective to cause the offset signal provided by said offset circuit to have a value which compensates for deviations of the center value of the length signal from a desired value.

2. An apparatus as defined in claim 1 wherein said peak measurement circuit has an effective measurement range with a center level and the control signal supplied by said offset calculation circuit causes the offset signal to have a value which gives the output signal from said adder circuit a center value corresponding to the center level of the measurement range of said peak measurement circuit.