Sewing Machine

Patent metadata

Field	Value
Publication number	US-2016273144-A1
Application number	US-201615009293-A
Country	US
Kind code	A1
Filing date	Jan 28, 2016
Priority date	Mar 20, 2015
Publication date	Sep 22, 2016
Grant date	—

Abstract

A sewing machine moves a presser foot up and down through a presser-bar lifting lever to depress a cloth. The lever is moved down by a stepping motor at a constant move-down amount. A compression spring is present between the stepping motor and the presser foot. The compression spring is compressed by some of the constant move-down amount of the lever, and applies, to the presser foot, pushing force canceling repulsive force from the depressed cloth. The move-down amount of the presser foot is detected by an encoder, and a thickness of the cloth is calculated by a cloth-thickness calculator. The cloth-thickness calculator performs calculation based on the move-down amounts at two timings in a time period at which the presser foot depresses the cloth and attempts to further move down.

First claim

What is claimed is:

1 . A sewing machine comprising:
a presser foot attached to a lower end of a presser bar supported by a sewing machine frame so as to be movable up and down, the presser foot depressing a cloth to be sewn; a lever linking to the presser foot moves up and down relative to the cloth; an actuator moving down the lever at a constant move-down amount to depress the cloth with the presser foot; an elastic body present between the actuator and the presser foot, the elastic body being compressed by the move-down operation of the lever at the constant move-down amount, and applying, to the presser foot, pushing force that cancels repulsive force from the depressed cloth; an encoder detecting a move-down amount of the presser foot; and a calculator calculating a thickness of the cloth based on the move-down amount detected by the encoder at two timings during a time period at which the presser foot depresses the cloth and attempts to further move down.

2 . The sewing machine according to claim 1 , wherein the calculator:
calculates the pushing force that is equal to the repulsive force based on a compression amount of the elastic body on a basis of the constant move-down amount of the lever and the move-down amount of the presser foot; calculates a height of the presser foot at a timing at which the calculated pushing force becomes zero; and determines the calculated height of the presser foot as the thickness of the cloth.

3 . The sewing machine according to claim 2 , wherein the calculator creates, based on an initial height Do of the presser foot, a spring constant ks of the elastic body, move-down amounts dc(t 1 ), dc(t 2 ) at two timings t 1 , t 2 , and swing-down amounts do(t 1 ), do(t 2 ) of the lever at the two timings t 1 , t 2 , simultaneous equations including two equations from a following formula, solves the simultaneous equations, and obtains a thickness Lo;
( Do−dc ( t )) = A×[ks× ( do ( t )− dc ( t ))]+ Lo, where
A and Lo are unknown quantities.

4 . The sewing machine according to claim 1 , wherein the calculator:
calculates a compression amount of the cloth at a predetermined timing based on the thickness of the cloth and a height of the presser foot; and calculates stretch properties of the cloth based on the pushing force by the elastic body and the compression amount of the cloth.

5 . The sewing machine according to claim 4 , further comprising a controller changing a sewing condition based on at least either the thickness of the cloth or the stretch properties.

Assignees

• Janome Sewing Machine Co Ltd

Inventors

• Koike Mikio
• Mafune Jun

Classifications

• D05D2209/16

  Thick threads or thick material · CPC title

• D05B29/02 Primary

  Presser-control devices · CPC title

• D05B19/16

  Control of workpiece movement, e.g. modulation of travel of feed dog · CPC title

• D05B73/12

  Slides; Needle plates · CPC title

• D05B29/12

  Presser-foot attachment · CPC title